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Sample records for exchange performances photoprotection

  1. Photoprotection

    Directory of Open Access Journals (Sweden)

    Rai Reena

    2007-01-01

    Full Text Available The deleritious effect of ultraviolet radiation on humans has increased the need for photoprotection. Sunscreens are widely used as photo protective agents. They are divided into chemical sunscreens which absorb high-energy ultraviolet rays and physical blockers which reflect or scatter light. Effectiveness of sunscreens depends upon sun protection factor and its substantivity. Clothing is also important for sun protection and its effectiveness is measured by Ultraviolet Protection Factor. There are many other agents with photo protective properties, which range from antioxidants to plant extracts to DNA repair enzymes. Usage of wide brimmed hats and sunglasses, avoidance of solar exposure at times of peak intensity, use of cover-up garments and sunscreen lotions are effective for photo protection of the skin.

  2. Technology Performance Exchange

    Energy Technology Data Exchange (ETDEWEB)

    2015-09-01

    To address the need for accessible, high-quality data, the Department of Energy has developed the Technology Performance Exchange (TPEx). TPEx enables technology suppliers, third-party testing laboratories, and other entities to share product performance data. These data are automatically transformed into a format that technology evaluators can easily use in their energy modeling assessments to inform procurement decisions.

  3. Skin cancer prevention in annual performance of total skin examination, photoprotection counseling, and patient instruction of self-skin examination.

    Science.gov (United States)

    Yiannias, James A; Laman, Susan D; Stevens, Ryan; Rkein, Ali M; Nelson, Evan; Noble, Brie N

    2014-08-01

    Prevention of skin cancer includes early diagnosis and photoprotection, such as by physician-performed total skin examination (TSE) and patient-performed self-skin examination (SSE). Hypothesizing that 90% of our patients receive an annual TSE, photoprotection counseling, and SSE instruction, we assessed the extent to which this was documented in patients' records. We also sought to identify differences in documentation of TSE, photoprotection counseling, and instruction on SSE with or without use of a dictation template prompting documentation. Retrospective review of a random sample of 400 patients in an outpatient dermatology practice of a tertiary care academic medical center for any dermatology appointment between May 1 and July 31, 2007. Exclusion criteria included refusal to undergo TSE, lack of access to skin (e.g., wheelchair-bound or in cast), or inappropriate visit type (e.g., for acne, psoriasis, or lupus). Of 400 randomly selected patients, 313 met inclusion criteria. The dictation template was used in 133; of these, 89% (119/133) had documentation in their clinical note of a TSE (exclusive of the buttocks or groin area), and 98% (130/133) had documentation of instruction on sun protection and SSE. Without use of the dictation template, these percentages dropped to 78% (140/180) and 20% (36/180), respectively. Physicians using a dictation template were more likely to document having conducted a TSE and instructed patients on photoprotection and SSE. A dictation template aids documentation of annual TSE and patient education efforts on photoprotection and SSE. © 2013 The International Society of Dermatology.

  4. Assessing heat exchanger performance data using temperature ...

    African Journals Online (AJOL)

    To ensure operation of heat exchangers, the goal is to verify that the exchanger is performing, or will perform, at its design. This is especially relevant to coolers that typically operate at heat loads reduced from their design basis. In addition, any calculated performance acceptance criteria must also consider uncertainty and ...

  5. New insights into pesticide photoprotection.

    Science.gov (United States)

    Trivella, Aurélien; Richard, Claire

    2014-04-01

    Photolysis may be a significant route of pesticide dissipation on crops, leading to an increase of pesticide use. Spraying strong absorbing compounds (photoprotector) along with pesticide is an attractive strategy to prevent the photodegradation phenomenon. The aim of this study is to get a better understanding of the parameters governing the photoprotection efficiency. Experiments were conducted using formulated sulcotrione as a pesticide and a grape wine extract as a photoprotector. These compounds were irradiated using simulated solar light as dried deposits on carnauba wax films or on disks of tobacco leaves and analyzed by ultra performance liquid chromatography ultraviolet (UV), spectroscopy, and microscopy. It is shown that photolysis is faster on leaves than on carnauba wax and that the photoprotection effect of grape wine extract is more efficient on leaves than on wax. Images recorded by microscopy bring evidence that deposits are very different on the two supports both in the absence and in the presence of the photoprotector. The grape wine extract plays a double role; it is antioxidant and UV screen. Photoprotection by the grape wine extract is a complex mixing of UV screen and antioxidant effects. The UV screen effect can be rationalized by considering the rate of light absorption by sulcotrione. Our results demonstrate that the rates of sulcotrione phototransformation are mainly governed by the repartition of the deposit on the solid support.

  6. Exchange Rate Deregulation and Industrial Performance: An ...

    African Journals Online (AJOL)

    The study found that a long-run relationship exists between the industrial productivity growth rate, ration of industrial production to gross domestic product, exchange rate, interest rate and terms of trade, and that exchange rate deregulation has significant impact on industrial performance. In order to determine the short term ...

  7. Brazilian Consensus on Photoprotection

    Science.gov (United States)

    Schalka, Sérgio; Steiner, Denise; Ravelli, Flávia Naranjo; Steiner, Tatiana; Terena, Aripuanã Cobério; Marçon, Carolina Reato; Ayres, Eloisa Leis; Addor, Flávia Alvim Sant'anna; Miot, Helio Amante; Ponzio, Humberto; Duarte, Ida; Neffá, Jane; da Cunha, José Antônio Jabur; Boza, Juliana Catucci; Samorano, Luciana de Paula; Corrêa, Marcelo de Paula; Maia, Marcus; Nasser, Nilton; Leite, Olga Maria Rodrigues Ribeiro; Lopes, Otávio Sergio; Oliveira, Pedro Dantas; Meyer, Renata Leal Bregunci; Cestari, Tânia; dos Reis, Vitor Manoel Silva; Rego, Vitória Regina Pedreira de Almeida

    2014-01-01

    Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of non-melanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection. PMID:25761256

  8. Current challenges in photoprotection.

    Science.gov (United States)

    Lim, Henry W; Arellano-Mendoza, Maria-Ivonne; Stengel, Fernando

    2017-03-01

    Electromagnetic radiation in the ultraviolet, visible, and infrared ranges all produce biologic effects. Ultraviolet filters are the most well-studied photoprotective measure for the adverse effects of ultraviolet radiation. Because of the reported endocrinologic effects of oxybenzone in animal studies, its effects on coral reefs, and its photocontact allergy potential, its use has been minimized in many countries worldwide. New developments in topical antioxidants and oral and subcutaneous agents (eg, Polypodium leucotomos extract, afamelanotide, nicotinamide) with photoprotective and antiphotocarcinogenic properties could potentially provide addition modalities for protection against the effects of visible light and infrared radiation. Copyright © 2016 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  9. Oral and systemic photoprotection.

    Science.gov (United States)

    Chen, Andrew C; Damian, Diona L; Halliday, Gary M

    2014-01-01

    Photoprotection can be provided not only by ultraviolet (UV) blockers but also by oral substances. Epidemiologically identified associations between foods and skin cancer and interventional experiments have discovered mechanisms of UV skin damage. These approaches have identified oral substances that are photoprotective in humans. UV inhibits adenosine triphosphate (ATP) production causing an energy crisis, which prevents optimal skin immunity and DNA repair. Enhancing ATP production with oral nicotinamide protects from UV immunosuppression, enhances DNA repair and reduces skin cancer in humans. Reactive oxygen species also contribute to photodamage. Nontoxic substances consumed in the diet, or available as oral supplements, can protect the skin by multiple potential mechanisms. These substances include polyphenols in fruit, vegetables, wine, tea and caffeine-containing foods. UV-induced prostaglandin E2 (PGE2 ) contributes to photodamage. Nonsteroidal anti-inflammatory drugs and food substances reduce production of this lipid mediator. Fish oils are photoprotective, at least partially by reducing PGE2 . Orally consumed substances, either in the diet or as supplements, can influence cutaneous responses to UV. A current research goal is to develop an oral supplement that could be used in conjunction with other sun protective strategies in order to provide improved protection from sunlight. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. real exchange rate misalignment and economic performance in ...

    African Journals Online (AJOL)

    KEYWORDS:Exchange rate misalignment,co-integration and economic growth. INTRODUCTION. Real exchange rate misalignment and economic performance has continued to gain currency in recent policy debates. This is because exchange rate misalignment may result in undesirable economic performance. Exchange.

  11. Real exchange rate misalignment and economic performance in ...

    African Journals Online (AJOL)

    This article investigates the behavior of equilibrium exchange rate and real exchange rate misalignment in Sudan over the period 1979– 2009. In addition, the impact of real exchange rate misalignment on economic performance is examined. The empirical results show that the equilibrium exchange rate is significantly ...

  12. Complex Heat Exchangers for Improved Performance

    Science.gov (United States)

    Bran, Gabriela Alejandra

    propagates along the channel. However, the sinusoidal behavior on one of the fluids does not fully translate to the other gets damped by the wall and the heat transfer coefficients that can be barely seen on the other flow. A scaling analysis and a parametric study were performed to determine the influence the different parameters on the system have on the time a heat exchanger takes to reach steady state. The results show the dependency of tst* (time a system takes to reach steady state) on the dimensionless parameters M, C, NTUh, NTUc, and Cw. t st* depends linearly on C and Cw, and it is a power function of M. It was also shown that tst* has a logarithmic dependency on NTUh and NTUc. A correlation was generated to approximate the time a system takes to reach steady state for systems where C w behavior during the system start-up was presented. In order to achieve the desired outlet steam temperature at a reasonable time, the system must operate at high gas mass flow rates. If the inlet temperature of the gas suffers a step change, it affects the reaction rate as well as the outlet steam temperature. A small perturbation on the gas mass flow rate has an effect on the profile shape. However, the maximum temperature reached by the gas due to reaction is not affected, and consequently, it has little effect on the steam temperature. Axial conduction in the reactor heat exchanger was also investigated, specifically in the gas section. Axial conduction cannot be assumed to be negligible in the reactor heat exchanger because of the iron-based catalytic bed. Results in this section show that axial conduction is detrimental for the system. It was found that for Peclet number greater than 100, axial conduction can be neglected. An alternative solution to address axial conduction was proposed, namely to include a well-insulated non-reacting section (without a catalytic bed) upstream of the reactor. The modified reactor heat exchanger was a novel solution to avoid the negative effect

  13. Photoprotective effects of nicotinamide.

    Science.gov (United States)

    Damian, Diona L

    2010-04-01

    Sun protective measures can reduce numbers of both precancerous actinic keratoses and cutaneous squamous cell carcinomas within relatively short periods of time even in high-risk populations. Sunscreens, which tend to provide greater protection against shortwave UVB than against longer wavelength UVA radiation, can however provide only partial protection from the mutagenic and immune suppressive effects of sunlight. In large part, this reflects poor compliance with proper sunscreen application and reapplication. Skin cancer is by far the most common malignancy in Caucasian populations, and additional strategies to reduce the morbidity and economic burden of this disease are now urgently needed. Nicotinamide, the amide form of vitamin B3, is an inexpensive agent which is used for a variety of dermatological applications with little or no toxicity even at high doses. Nicotinamide has photoprotective effects against carcinogenesis and immune suppression in mice, and is photoimmunoprotective in humans when used as a lotion or orally. UV irradiation depletes keratinocytes of cellular energy and nicotinamide, which is a precursor of nicotinamide adenine dinucleotide, may act at least in part by providing energy repletion to irradiated cells.

  14. Growth form defines physiological photoprotective capacity in intertidal benthic diatoms.

    Science.gov (United States)

    Barnett, Alexandre; Méléder, Vona; Blommaert, Lander; Lepetit, Bernard; Gaudin, Pierre; Vyverman, Wim; Sabbe, Koen; Dupuy, Christine; Lavaud, Johann

    2015-01-01

    In intertidal marine sediments, characterized by rapidly fluctuating and often extreme light conditions, primary production is frequently dominated by diatoms. We performed a comparative analysis of photophysiological traits in 15 marine benthic diatom species belonging to the four major morphological growth forms (epipelon (EPL), motile epipsammon (EPM-M) and non-motile epipsammon (EPM-NM) and tychoplankton (TYCHO)) found in these sediments. Our analyses revealed a clear relationship between growth form and photoprotective capacity, and identified fast regulatory physiological photoprotective traits (that is, non-photochemical quenching (NPQ) and the xanthophyll cycle (XC)) as key traits defining the functional light response of these diatoms. EPM-NM and motile EPL showed the highest and lowest NPQ, respectively, with EPM-M showing intermediate values. Like EPL, TYCHO had low NPQ, irrespective of whether they were grown in benthic or planktonic conditions, reflecting an adaptation to a low light environment. Our results thus provide the first experimental evidence for the existence of a trade-off between behavioural (motility) and physiological photoprotective mechanisms (NPQ and the XC) in the four major intertidal benthic diatoms growth forms using unialgal cultures. Remarkably, although motility is restricted to the raphid pennate diatom clade, raphid pennate species, which have adopted a non-motile epipsammic or a tychoplanktonic life style, display the physiological photoprotective response typical of these growth forms. This observation underscores the importance of growth form and not phylogenetic relatedness as the prime determinant shaping the physiological photoprotective capacity of benthic diatoms.

  15. Photoprotective activity of Buddleja scordioides.

    Science.gov (United States)

    Avila Acevedo, J G; Castañeda, C M C; Benitez, F J C; Durán, D A; Barroso, V R; Martínez, C G; Muñoz, L J L; Martínez, C A; Romo de Vivar, A

    2005-06-01

    The purpose of this study was to determine the photoprotective properties of the methanolic extract of Buddleja scordioides, as well as verbascoside and linarin which were isolated from this extract, and linarin acetate prepared in the laboratory. The photoprotective effect of substances against UV-B induced cellular death was evaluated by challenge experiments using Escherichia coli. Verbascoside and linarin acetate showed the highest protection. The sun protection factor (SPF) of the methanolic extract, linarin, linarin acetate, and verbascoside was evaluated by guinea pig bioassays. Verbascoside showed the largest SPF measurement.

  16. Natural products as photoprotection.

    Science.gov (United States)

    Saewan, Nisakorn; Jimtaisong, Ampa

    2015-03-01

    The rise in solar ultraviolet radiation on the earth's surface has led to a depletion of stratospheric ozone over recent decades, thus accelerating the need to protect human skin against the harmful effects of UV radiation such as erythema, edema, hyperpigmentation, photoaging, and skin cancer. There are many different ways to protect skin against UV radiation's harmful effects. The most popular way to reduce the amount of UV radiation penetrating the skin is topical application of sunscreen products that contain UV absorbing or reflecting active molecules. Based on their protection mechanism, the active molecules in sunscreens are broadly divided into inorganic and organic agents. Inorganic sunscreens reflect and scatter UV and visible radiation, while organic sunscreens absorb UV radiation and then re-emit energy as heat or light. These synthetic molecules have limited concentration according to regulation concern. Several natural compounds with UV absorption property have been used to substitute for or to reduce the quantity of synthetic sunscreen agents. In addition to UV absorption property, most natural compounds were found to act as antioxidants, anti-inflammatory, and immunomodulatory agents, which provide further protection against the damaging effects of UV radiation exposure. Compounds derived from natural sources have gained considerable attention for use in sunscreen products and have bolstered the market trend toward natural cosmetics. This adds to the importance of there being a wide selection of active molecules in sunscreen formulations. This paper summarizes a number of natural products derived from propolis, plants, algae, and lichens that have shown potential photoprotection properties against UV radiation exposure-induced skin damage. © 2015 Wiley Periodicals, Inc.

  17. Photoprotective, excited-state quenching mechanisms in diverse photosynthetic organisms.

    Science.gov (United States)

    Magdaong, Nikki Cecil M; Blankenship, Robert E

    2018-01-03

    Light-harvesting complexes (LHCs) serve a dual role in photosynthesis, depending on the prevailing light conditions. In low light, they ensure photosynthetic efficiency by maximizing the light absorption cross-section and subsequent energy storage. Under excess light conditions, LHCs perform photoprotective quenching functions to prevent harmful chemical species such as triplet chlorophyll and singlet oxygen from forming and damaging the photosynthetic apparatus. In this minireview, various photoprotective quenching mechanisms that have been identified in different photosynthetic organisms are surveyed and summarized, and implications for improving photosynthetic productivity are briefly discussed. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Performance and turnover intentions: a social exchange perspective

    NARCIS (Netherlands)

    Biron, M.; Boon, C.

    2013-01-01

    Purpose - Prior research has yielded mixed results regarding the relationship between performance and turnover intentions. Drawing from social exchange theory, the purpose of this paper is to propose that the performance-turnover intentions association may be contingent upon individuals' exchange

  19. Exchange Rate Deregulation and Industrial Performance: An ...

    African Journals Online (AJOL)

    FIRST LADY

    CIPG = βo + β1EXR + β2INTR + β3TOT + µ2............. (iii). Where IPGR is industrial productivity growth rate and it is calculated as;. IPGR = (IOt-1 – IOt)/IOt-1. IO is index of industrial output. CIPG is contribution of industrial production to GDP, calculated as;. CIPG = (IO/GDP) X 100/1. Exchange Rate Deregulation and Industrial ...

  20. Performance testing of a two-phase interface heat exchanger

    Science.gov (United States)

    Mccabe, M. E., Jr.; Swanson, T. D.

    1989-01-01

    This paper describes the design and performance testing of a heat exchanger which interfaces separate two-phase ammonia thermal loops. The basic design involves a tube-in-tube concept, with boiling occurring in the inner tube and condensation in the outer tube. Eight such tubes are arranged in parallel. Testing has demonstrated that up to 8.2 kW of heat may be transferred across the heat exchanger when the saturation temperature difference between the systems is 5 C. Performance of the heat exchanger is affected primarily by the mass flow rate of ammonia in the liquid supply loop.

  1. Antioxidant activity and potential photoprotective from amazon native flora extracts.

    Science.gov (United States)

    Martins, Francislene J; Caneschi, César A; Vieira, José L F; Barbosa, Wagner; Raposo, Nádia R B

    2016-08-01

    Plant species are sources of active compounds that can fight and/or prevent damage caused by reactive oxygen species, which enables the development of natural products that can help to prevent premature aging caused by exposure to solar radiation. This study assessed the antioxidant and photoprotective activities of six dried extracts of plants from the Brazilian Amazon biome. Plant extracts were prepared in 70% (v/v) ethanol by dynamic maceration for 72h in the dark, and then filtered, concentrated and lyophilized. The extracts were subjected to a phytochemical screening. The antioxidant activity was measured using a 2,2-diphenyl-1-picrylhydrazyl assay and the photoprotection assay was performed using the diffuse transmittance technique. The data obtained from the antioxidant activity assay was evaluated by Student's t-test for independent samples, with the aid of Statistical Package for Social Sciences v.14.0 for Windows software. The flavonoids represent a special metabolites class present in all analyzed extracts. The antioxidant activity (μgmL(-1)) decreased in the following order: Aniba canelilla (1.80±0.16), Brosimum acutifolium (2.84±0.38), Dalbergia monetaria (5.46±0.17) or Caesalpinia pyramidalis (6.45±1.18), Arrabidaea chica (15.35±0.86), and Aspidosperma nitidum (99.14±2.3). Only D. monetaria showed a considerable sun protection factor allowing for labeling (6.0±0.3). The D. monetaria extract was considered the most promising sample because it had optimal antioxidant and photoprotective activities against solar radiation, considering the limit established by regulatory agencies. These extracts with antioxidant potential can be used in photoprotective formulations, providing synergistic photoprotective effect or elevating the adeed value of the product. Additionally, these formulations are attractive to a population who searchs for products made with natural ingredients. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Influencing parameters on performance of a mantle heat exchanger ...

    African Journals Online (AJOL)

    Thermal performance of a solar water heater mainly depends on the thermal stratification. Thermal stratification in solar water tanks is essential for a better performance of energy storage systems where these tanks are integrated. In this research work, the performance of a solar water heater with a mantle heat exchanger is ...

  3. Herbal Cosmeceuticals for Photoprotection from Ultraviolet B ...

    African Journals Online (AJOL)

    By quenching free radicals, antioxidants may aid photoprotection effect. This review focuses on photoprotection from UVB radiation and discusses potential herbal candidates with antioxidant properties that can serve as a strong barrier in cosmeceuticals to protect skin against harmful UVB rays. Keywords: Cosmeceutials ...

  4. Thermal performance modeling of cross-flow heat exchangers

    CERN Document Server

    Cabezas-Gómez, Luben; Saíz-Jabardo, José Maria

    2014-01-01

    This monograph introduces a numerical computational methodology for thermal performance modeling of cross-flow heat exchangers, with applications in chemical, refrigeration and automobile industries. This methodology allows obtaining effectiveness-number of transfer units (e-NTU) data and has been used for simulating several standard and complex flow arrangements configurations of cross-flow heat exchangers. Simulated results have been validated through comparisons with results from available exact and approximate analytical solutions. Very accurate results have been obtained over wide ranges

  5. Application of transient analysis methodology to heat exchanger performance monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Rampall, I.; Soler, A.I.; Singh, K.P. [Holtec International, Cherry Hill, NJ (United States); Scott, B.H. [Baltimore Gas and Electric Co., Lusby, MD (United States)

    1994-12-31

    A transient testing technique is developed to evaluate the thermal performance of industrial scale heat exchangers. A Galerkin-based numerical method with a choice of spectral basis elements to account for spatial temperature variations in heat exchangers is developed to solve the transient heat exchanger model equations. Testing a heat exchanger in the transient state may be the only viable alternative where conventional steady state testing procedures are impossible or infeasible. For example, this methodology is particularly suited to the determination of fouling levels in component cooling water system heat exchangers in nuclear power plants. The heat load on these so-called component coolers under steady state conditions is too small to permit meaningful testing. An adequate heat load develops immediately after a reactor shutdown when the exchanger inlet temperatures are highly time-dependent. The application of the analysis methodology is illustrated herein with reference to an in-situ transient testing carried out at a nuclear power plant. The method, however, is applicable to any transient testing application.

  6. 2011 PERFORMANCE ASSESSMENT COMMUNITY OF PRACTICE TECHNICAL EXCHANGE - SUMMARY

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, R.

    2011-12-30

    The Performance Assessment Community of Practice (PA CoP) was developed in 2008 to improve consistency and quality in the preparation of performance assessments (PAs) and risk assessments across the Department of Energy (DOE) Complex. The term, PA, is used to represent all of these modeling applications in this report. The PA CoP goals are to foster the exchange of information among PA practitioners and to share lessons learned from PAs conducted for DOE, commercial disposal facilities, and international entities. Technical exchanges and workshops are a cornerstone of PA CoP activities. Previous technical exchanges have addressed Engineered Barriers (2009 - http://www.cresp.org/education/workshops/pacop/), the Advanced Simulation Capability for Environmental Management and the Cementitious Barriers Partnership (2010 - http://srnl.doe.gov/copexchange/links.htm). Each technical exchange also includes summary presentations regarding activities at DOE, the Nuclear Regulatory Commission (NRC) and other organizations (e.g., International Atomic Energy Agency (IAEA)) as well as a number of presentations from selected sites to provide insight and perspective from on-going modeling activities. Through the deployment of PA Assistance Teams, the PA CoP has also been engaged in the development of new PAs across the DOE Complex. As a way of improving consistency in the preparation of new PAs, the teams provide technical advice and share experiences, noteworthy practices, and lessons learned from previous Low-Level Waste Disposal Facility Federal Review Group (LFRG) reviews. Teams have provided support for PAs at Hanford, Idaho, Paducah and Portsmouth. The third annual PA CoP Technical Exchange was held on May 25-26, 2011 in Atlanta, GA. The PA CoP Steering Committee Meeting held its first meeting on May 24 prior to the Technical Exchange. Decision making using models and software quality assurance were the topical emphasis for the exchange. A new feature at the 2011 technical

  7. Leader-member exchange, work engagement, and job performance

    NARCIS (Netherlands)

    Breevaart, K.; Bakker, A.B.; Demerouti, E.; van den Heuvel, M.

    2015-01-01

    Purpose - The purpose of this paper is to examine the process through which leader-member exchange (LMX) is related to followers’ job performance. Integrating the literature on LMX theory and resource theories, the authors hypothesized that the positive relationship between LMX and employee job

  8. Leader-member exchange, work engagement, and job performance.

    NARCIS (Netherlands)

    Breevaart, K.; Bakker, A. B.; Demerouti, E.; Van den Heuvel, M.

    2015-01-01

    Purpose - The purpose of this paper is to examine the process through which leader-member exchange (LMX) is related to followers’ job performance. Integrating the literature on LMX theory and resource theories, the authors hypothesized that the positive relationship between LMX and employee job

  9. Study on finned pipe performance as a ground heat exchanger

    Science.gov (United States)

    Lin, Qinglong; Ma, Jinghui; Shi, Lei

    2017-08-01

    The GHEs (ground heat exchangers) is an important element that determines the thermal efficiency of the entire ground-source heat-pump system. The aim of the present study is to clarify thermal performance of a new type GHE pipe, which consists straight fins of uniform cross sectional area. In this paper, GHE model is introduced and an analytical model of new type GHE pipe is developed. The heat exchange rate of BHEs utilizing finned pips is 40.42 W/m, which is 16.3% higher than normal BHEs, based on simulation analyses.

  10. Enabling Detailed Energy Analyses via the Technology Performance Exchange: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Studer, D.; Fleming, K.; Lee, E.; Livingood, W.

    2014-08-01

    One of the key tenets to increasing adoption of energy efficiency solutions in the built environment is improving confidence in energy performance. Current industry practices make extensive use of predictive modeling, often via the use of sophisticated hourly or sub-hourly energy simulation programs, to account for site-specific parameters (e.g., climate zone, hours of operation, and space type) and arrive at a performance estimate. While such methods are highly precise, they invariably provide less than ideal accuracy due to a lack of high-quality, foundational energy performance input data. The Technology Performance Exchange was constructed to allow the transparent sharing of foundational, product-specific energy performance data, and leverages significant, external engineering efforts and a modular architecture to efficiently identify and codify the minimum information necessary to accurately predict product energy performance. This strongly-typed database resource represents a novel solution to a difficult and established problem. One of the most exciting benefits is the way in which the Technology Performance Exchange's application programming interface has been leveraged to integrate contributed foundational data into the Building Component Library. Via a series of scripts, data is automatically translated and parsed into the Building Component Library in a format that is immediately usable to the energy modeling community. This paper (1) presents a high-level overview of the project drivers and the structure of the Technology Performance Exchange; (2) offers a detailed examination of how technologies are incorporated and translated into powerful energy modeling code snippets; and (3) examines several benefits of this robust workflow.

  11. Review of cell performance in anion exchange membrane fuel cells

    Science.gov (United States)

    Dekel, Dario R.

    2018-01-01

    Anion exchange membrane fuel cells (AEMFCs) have recently received increasing attention since in principle they allow for the use of non-precious metal catalysts, which dramatically reduces the cost per kilowatt of power in fuel cell devices. Until not long ago, the main barrier in the development of AEMFCs was the availability of highly conductive anion exchange membranes (AEMs); however, improvements on this front in the past decade show that newly developed AEMs have already reached high levels of conductivity, leading to satisfactory cell performance. In recent years, a growing number of research studies have reported AEMFC performance results. In the last three years, new records in performance were achieved. Most of the literature reporting cell performance is based on hydrogen-AEMFCs, although an increasing number of studies have also reported the use of fuels others than hydrogen - such as alcohols, non-alcohol C-based fuels, as well as N-based fuels. This article reviews the cell performance and performance stability achieved in AEMFCs through the years since the first reports in the early 2000s.

  12. Analysis performance of proton exchange membrane fuel cell (PEMFC)

    Science.gov (United States)

    Mubin, A. N. A.; Bahrom, M. H.; Azri, M.; Ibrahim, Z.; Rahim, N. A.; Raihan, S. R. S.

    2017-06-01

    Recently, the proton exchange membrane fuel cell (PEMFC) has gained much attention to the technology of renewable energy due to its mechanically ideal and zero emission power source. PEMFC performance reflects from the surroundings such as temperature and pressure. This paper presents an analysis of the performance of the PEMFC by developing the mathematical thermodynamic modelling using Matlab/Simulink. Apart from that, the differential equation of the thermodynamic model of the PEMFC is used to explain the contribution of heat to the performance of the output voltage of the PEMFC. On the other hand, the partial pressure equation of the hydrogen is included in the PEMFC mathematical modeling to study the PEMFC voltage behaviour related to the input variable input hydrogen pressure. The efficiency of the model is 33.8% which calculated by applying the energy conversion device equations on the thermal efficiency. PEMFC’s voltage output performance is increased by increasing the hydrogen input pressure and temperature.

  13. Thermal Performance Study of a Prototype Multiport Heat Exchanger

    Science.gov (United States)

    Fotowat, Shahram

    Great efforts have been made to investigate the thermal performance and fluid flow behaviour in Minichannel Heat Exchangers (MICHX), however, the examination of air side in a multiport serpentine slab heat exchanger is rare. In the current investigation, experiments were conducted on air heating via a prototype multiport MICHX. Hot DI-water at different mass flow rates and a constant inlet temperature of 70°C was passed through the channels. The water side Reynolds numbers were varied from 255 to 411. The airside Reynolds numbers were calculated based on the free mean stream velocity and varied from 1750 to 5250, while, the air inlet temperatures were in the range of 22.5°C to 34.5°C. The effects of dimensional parameters, such as Reynolds number, Nusselt number, Prandtl number, Brinkman number, and Dean number on the heat transfer performance were investigated. The effect of the serpentine on the enhancement of DI water thermal performance behaviour was studied. Heat transfer correlations were established and compared to the results in the open literature.

  14. Thermal Performance Analyses of Multiborehole Ground Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Wanjing Luo

    2017-01-01

    Full Text Available Geothermal energy known as a clean, renewable energy resource is widely available and reliable. Ground heat exchangers (GHEs can assist the development of geothermal energy by reducing the capital cost and greenhouse gas emission. In this paper, a novel semianalytical method was developed to study the thermal performance of multiborehole ground heat exchangers (GHEs with arbitrary configurations. By assuming a uniform inlet fluid temperature (UIFT, instead of uniform heat flux (UHF, the effects of thermal interference and the thermal performance difference between different boreholes can be examined. Simulation results indicate that the monthly average outlet fluid temperatures of GHEs will increase gradually while the annual cooling load of the GHEs is greater than the annual heating load. Besides, two mechanisms, the thermal dissipation and the heat storage effect, will determine the heat transfer underground, which can be further divided into four stages. Moreover, some boreholes will be malfunctioned; that is, boreholes can absorb heat from ground when the GHEs are under the cooling mode. However, as indicated by further investigations, this malfunction can be avoided by increasing borehole spacing.

  15. Photoprotection: part I. Photoprotection by naturally occurring, physical, and systemic agents.

    Science.gov (United States)

    Jansen, Rebecca; Wang, Steven Q; Burnett, Mark; Osterwalder, Uli; Lim, Henry W

    2013-12-01

    The acute and chronic consequences of ultraviolet radiation on human skin are reviewed. An awareness of variations in naturally occurring photoprotective agents and the use of glass, sunglasses, and fabric can lead to effective protection from the deleterious effects of ultraviolet radiation. New systemic agents, including Polypodium leucotomos, afamelanotide, and antioxidants have potential as photoprotective agents. Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  16. Investigations on the performance of chevron type plate heat exchangers

    Science.gov (United States)

    Dutta, Oruganti Yaga; Nageswara Rao, B.

    2018-01-01

    This paper presents empirical relations for the chevron type plate heat exchangers (PHEs) and demonstrated their validity through comparison of test data of PHEs. In order to examine the performance of PHEs, the pressure drop(Δ P), the overall heat transfer coefficient ( U m ) and the effectiveness ( ɛ) are estimated by considering the properties of plate material and working fluid, number of plates ( N t ) and chevron angle( β). It is a known fact that, large surface area of the plate provides more rate of heat transfer ( \\dot{Q} ) thereby more effectiveness ( ɛ). However, there is a possibility to achieve the required performance by increasing the number of plates without altering the plate dimensions, which avoids the new design of the system. Application of the Taguchi's design of experiments is examined with less number of experiments and demonstrated by setting the levels for the parameters and compared the test data with the estimated output responses.

  17. Herbal Cosmeceuticals for Photoprotection from Ultraviolet B ...

    African Journals Online (AJOL)

    To reduce ROS generation and damage, researchers recommend using sunscreen to protect the skin from harmful UVR. The realm of possibilities in photoprotection may include the development of sunscreens which remain at the surface of the skin for a longer time and may incorporate antioxidants that can neutralize ...

  18. North Dakota Metropolitan Planning Organization's peer exchange on introducing performance management into the MPO planning process : A TPCB Exchange

    Science.gov (United States)

    2013-06-19

    This report highlights key recommendations and noteworthy practices identified at the peer exchange on Introducing Performance Management into the Metropolitan Planning Organization (MPO) Planning Process held on June, 19, 2013 in Bismarck, Nor...

  19. Exchange inlet optimization by genetic algorithm for improved RBCC performance

    Science.gov (United States)

    Chorkawy, G.; Etele, J.

    2017-09-01

    A genetic algorithm based on real parameter representation using a variable selection pressure and variable probability of mutation is used to optimize an annular air breathing rocket inlet called the Exchange Inlet. A rapid and accurate design method which provides estimates for air breathing, mixing, and isentropic flow performance is used as the engine of the optimization routine. Comparison to detailed numerical simulations show that the design method yields desired exit Mach numbers to within approximately 1% over 75% of the annular exit area and predicts entrained air massflows to between 1% and 9% of numerically simulated values depending on the flight condition. Optimum designs are shown to be obtained within approximately 8000 fitness function evaluations in a search space on the order of 106. The method is also shown to be able to identify beneficial values for particular alleles when they exist while showing the ability to handle cases where physical and aphysical designs co-exist at particular values of a subset of alleles within a gene. For an air breathing engine based on a hydrogen fuelled rocket an exchange inlet is designed which yields a predicted air entrainment ratio within 95% of the theoretical maximum.

  20. Real exchange rate misalignment and economic performance in ...

    African Journals Online (AJOL)

    The objective of the study had been to investigate the impact of real exchange rate misalignment on economic growth in Nigeria. This paper adopted purchasing power parity index, the parallel market index and the model-based index of exchange rate misalignment to investigate the effects of real exchange rate ...

  1. Increased exposure to UV-B radiation during early development leads to enhanced photoprotection and improved long-term performance in Lactuca sativa.

    Science.gov (United States)

    Wargent, Jason J; Elfadly, Eslam M; Moore, Jason P; Paul, Nigel D

    2011-08-01

    Plant responses to solar UV radiation are numerous and have often been considered from a perspective of negative outcomes for plant productivity. In this study, we used two experimental approaches consisting of: (1) field-based spectrally modifying filters in addition to (2) controlled indoor exposure to UV-B, to examine the effects of UV radiation on growth and photosynthetic performance of lettuce (Lactuca sativa L.) seedlings. Various aspects of growth were affected in plants grown under a UV-inclusive environment compared to a UV-depleted environment, including reductions in leaf expansion, increases in leaf thickness and the rate of net photosynthesis. After transplantation to a uniform field environment, lettuce plants initially propagated under the UV-inclusive environment exhibited higher harvestable yields than those from a UV-depleted environment. In controlled conditions, photosynthetic rates were higher in plants grown in the presence of UV-B radiation, and relative growth of plants pre-acclimatized to UV-B was also increased, in addition to higher maximum photochemical efficiency of photosystem II (PSII) (F(v) /F(m) ) following subsequent exposure to high photosynthetically active radiation (PAR) and temperature stress. Our findings are discussed within the context of sustainability in agriculture and the paradigm shift in photobiology which such beneficial responses to UV radiation could represent. © 2011 Blackwell Publishing Ltd.

  2. Ex vivo assessment and validation of water exchange performance of 23 heat and moisture exchangers for laryngectomized patients.

    Science.gov (United States)

    van den Boer, Cindy; Muller, Sara H; Vincent, Andrew D; van den Brekel, Michiel W M; Hilgers, Frans J M

    2014-08-01

    Breathing through a tracheostoma results in insufficient warming and humidification of the inspired air. This loss of air conditioning, especially humidification, can be partially restored with the application of a heat and moisture exchanger (HME) over the tracheostoma. For medical professionals, it is not easy to judge differences in water exchange performance of various HMEs owing to the lack of universal outcome measures. This study has three aims: assessment of the water exchange performance of commercially available HMEs for laryngectomized patients, validation of these results with absolute humidity outcomes, and assessment of the role of hygroscopic salt present in some of the tested HMEs. Measurements of weight and absolute humidity at end inspiration and end expiration at different breathing volumes of a healthy volunteer were performed using a microbalance and humidity sensor. Twenty-three HMEs from 6 different manufacturers were tested. Associations were determined between core weight, weight change, breathing volume, and absolute humidity, using both linear and nonlinear mixed effects models. Water exchange of the 23 HMEs at a breathing volume of 0.5 L varies between 0.5 and 3.6 mg. Both water exchange and wet core weight correlate strongly with the end-inspiratory absolute humidity values (r2 =0.89/0.87). Hygroscopic salt increases core weight. The 23 tested HMEs for laryngectomized patients show wide variation in water exchange performance. Water exchange correlates well with the end-inspiratory absolute humidity outcome, which validates the ex vivo weight change method. Wet core weight is a predictor of HME performance. Hygroscopic salt increases the weight of the core material. The results of this study can help medical professionals to obtain a more founded opinion about the performance of available HMEs for pulmonary rehabilitation in laryngectomized patients, and allow them to make an informed decision about which HME type to use.

  3. 9Real exchange rate misalignment and economic performance in ...

    African Journals Online (AJOL)

    an exchange rate is described as overvalued or undervalued when it appreciates over or depreciates under its equilibrium level – both situations refer to a misalignment. Exchange rate overvaluation can damage the potential economic growth of a country through foreign currency shortage, large current account deficits and ...

  4. Omega-3 polyunsaturated fatty acids: photoprotective macronutrients.

    Science.gov (United States)

    Pilkington, Suzanne M; Watson, Rachel E B; Nicolaou, Anna; Rhodes, Lesley E

    2011-07-01

    Ultraviolet radiation (UVR) in sunlight has deleterious effects on skin, while behavioural changes have resulted in people gaining more sun exposure. The clinical impact includes a year-on-year increase in skin cancer incidence, and topical sunscreens alone provide an inadequate measure to combat overexposure to UVR. Novel methods of photoprotection are being targeted as additional measures, with growing interest in the potential for systemic photoprotection through naturally sourced nutrients. Omega-3 polyunsaturated fatty acids (n-3 PUFA) are promising candidates, showing potential to protect the skin from UVR injury through a range of mechanisms. In this review, we discuss the biological actions of n-3 PUFA in the context of skin protection from acute and chronic UVR overexposure and describe how emerging new technologies such as nutrigenomics and lipidomics assist our understanding of the contribution of such nutrients to skin health. © 2011 John Wiley & Sons A/S.

  5. BB creams and their photoprotective effect.

    Science.gov (United States)

    Couteau, Céline; Paparis, Eva; Coiffard, Laurence J M

    2016-01-01

    BB creams appeared on the market quite recently. These creams, which give a perfect complexion by covering up the skin's blemishes, have a photoprotective effect in the majority of cases. An SPF value ranging from 10 to 45 concerning the products we tested is displayed on the packaging. The 21 commercially-available BB creams were tested to assess their efficacy (determination of the SPF) and their photostability (determination of their efficacy after UV irradiation). It was shown that 70% of the products tested have an SPF determined in vitro by us which matches the SPF displayed on the product. For the remaining 30%, it can be seen that products have SPF values of between 2 and 10 times lower than those indicated on the products. It can also be noted that there is a large disparity in terms of photostability since, under the same experimental conditions, however, some products only lose 5% of their photoprotective efficacy, whereas others lose 60%.

  6. DNA Dosimetry Assessment for Sunscreen Genotoxic Photoprotection

    OpenAIRE

    André Passaglia Schuch; Juliana Carvalhães Lago; Teiti Yagura; Carlos Frederico Martins Menck

    2012-01-01

    BACKGROUND: Due to the increase of solar ultraviolet radiation (UV) incidence over the last few decades, the use of sunscreen has been widely adopted for skin protection. However, considering the high efficiency of sunlight-induced DNA lesions, it is critical to improve upon the current approaches that are used to evaluate protection factors. An alternative approach to evaluate the photoprotection provided by sunscreens against daily UV radiation-induced DNA damage is provided by the systemat...

  7. [Riboflavin photoprotection with cross-linking effect in photorefractive ablation of the cornea].

    Science.gov (United States)

    Kornilovskiy, I M; Sultanova, A I; Burtsev, A A

    2016-01-01

    Photorefractive ablation is inevitably accompanied by oxidative stress of the cornea and weakening of its biomechanical and photoprotective properties. To validate the expediency of riboflavin use in photorefractive ablation for photoprotection of the cornea and cross-linking. The effects of riboflavin use in photorefractive ablation was first studied in a series of in vitro and in vivo experiments performed on 56 eyes of 28 rabbits, and then on 232 eyes of 142 patients with different degrees of myopia. Biomechanical testing of corneal samples was performed with Zwick/RoellВZ 2.5/TN1S tensile-testing machine. Transepithelial photorefractive keratectomy (TransPRK) and femtosecond laser-assisted in situ keratomileusis (Femto-LASIK) were performed on Wavelight-Allegretto200, MEL-80, and WaveLight-EX500 excimer laser systems and also VisuMax and WaveLight-FS200 femtosecond lasers. For preliminary examinations, an appropriate set of diagnostic tools was used. In vivo experiments have proved that, in the absence of conservative therapy, riboflavin is able to produce both photoprotective and cross-linking effects to the cornea. Corneal syndrome was thus reduced and re-epithelialization after TransPRK accelerated. Biomechanical testing of corneal samples revealed an increase in tolerated load from 12.9±1.4 N to 18.3±1.2 N (p=0.0002) and tensile strength from 8.6±1.7 MPa to 12.4±1.7 MPa (p=0.007). Clinical studies conducted in a group of patients with mild to moderate myopia have also confirmed the photoprotective effect of riboflavin at months 1-12 after TransPRK. There were no significant differences in uncorrected visual acuity (ranged from 0.80±0.16 to 0.85±0.15) and corrected visual acuity at baseline (0.83±0.14). Evaluation of the optical and refractive effect achieved after Femto-LASIK with riboflavin photoprotection in the fellow eye has shown that this technique is not inferior to the traditional one as to its refractive accuracy, but provides better

  8. Topical isoflavones provide effective photoprotection to skin.

    Science.gov (United States)

    Lin, Jing-Yi; Tournas, Joshua A; Burch, James A; Monteiro-Riviere, Nancy A; Zielinski, Jan

    2008-04-01

    Isoflavones, one main group of phytoestrogens, have antioxidative and photoprotective effects in cellular and mouse studies. The aim of this study is to obtain a more comprehensive understanding of the isoflavone-mediated photoprotection with the pig skin model, a more human-resembling model. The pig skin was treated with five well-known isoflavone compounds (genistein, equol, daidzein, biochanin A, and formononetin) and one antioxidant combination solution of 15% vitamin C and 1% vitamin E and 0.5% ferulic acid (CEF) daily for 4 days. Skin was irradiated with solar-simulated UV irradiation, 1 to 5 minimal erythema dose (MED) at 1-MED intervals. Evaluation was carried out 24 h later by colorimeter-measured erythema and sunburn cell numbers. Topical application of 0.5% solutions of three individual phytoestrogens - genistein, daidzein, biochanin A - are better than similar solutions of equol or formononetin in protecting pig skin from solar-simulated ultraviolet (SSUV)-induced photodamage, as measured by sunburn cell formation and/or erythema. However, the protection was less than that provided by a topical combination antioxidant standard containing 15% L-ascorbic acid, 1%alpha-tocopherol, and 0.5% ferulic acid. Isoflavones provide effective photoprotection and are good candidate ingredients for protection against ultraviolet (UV) photodamage.

  9. Photoprotection of human skin beyond ultraviolet radiation.

    Science.gov (United States)

    Grether-Beck, Susanne; Marini, Alessandra; Jaenicke, Thomas; Krutmann, Jean

    2014-01-01

    Photoprotection of human skin by means of sunscreens or daily skin-care products is traditionally centered around the prevention of acute (e.g. sunburn) and chronic (e.g. skin cancer and photoaging) skin damage that may result from exposure to ultraviolet rays (UVB and UVA). Within the last decade, however, it has been appreciated that wavelengths beyond the ultraviolet spectrum, in particular visible light and infrared radiation, contribute to skin damage in general and photoaging of human skin in particular. As a consequence, attempts have been made to develop skin care/sunscreen products that not only protect against UVB or UVA radiation but provide photoprotection against visible light and infrared radiation as well. In this article, we will briefly review the current knowledge about the mechanisms responsible for visible light/infrared radiation-induced skin damage and then, based on this information, discuss strategies that have been successfully used or may be employed in the future to achieve photoprotection of human skin beyond ultraviolet radiation. In this regard we will particularly focus on the use of topical antioxidants and the challenges that result from the task of showing their efficacy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Humidification performance of heat and moisture exchangers for pediatric use.

    Science.gov (United States)

    Chikata, Yusuke; Sumida, Chihiro; Oto, Jun; Imanaka, Hideaki; Nishimura, Masaji

    2012-01-01

    Background. While heat and moisture exchangers (HMEs) have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH(2)O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small) and 5.1 L/min (large) when pressure was 10 cmH(2)O. We measured absolute humidity (AH) at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L), decreasing further (19.7 to 27.3 mg/L) with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent.

  11. Humidification Performance of Heat and Moisture Exchangers for Pediatric Use

    Directory of Open Access Journals (Sweden)

    Yusuke Chikata

    2012-01-01

    Full Text Available Background. While heat and moisture exchangers (HMEs have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH2O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small and 5.1 L/min (large when pressure was 10 cmH2O. We measured absolute humidity (AH at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L, decreasing further (19.7 to 27.3 mg/L with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent.

  12. Determinants of International Outsourcing and Performance: A Relational Exchange Perspective

    Directory of Open Access Journals (Sweden)

    Carl E. Dresden

    2013-07-01

    Full Text Available Prescriptive discussions regarding international outsourcing abound, but there are few previously proposed models of the antecedents leading to such sourcing. This empirical study utilizes the relational exchange framework proposed by Dwyer, Schurr and Oh (1987 and builds a conceptual model of the firm's use of international outsourcing within the context of relational exchange. The model concentrates on the aspects of relational exchange that are crucial antecedents to successful international outsourcing and empirically demonstrates how both economic and social factors have their influence. The resulting model demonstrates how cooperation, rather than competition, leads to successful international outsourcing.

  13. The joint effects of personality and workplace social exchange relationships in predicting task performance and citizenship performance.

    Science.gov (United States)

    Kamdar, Dishan; Van Dyne, Linn

    2007-09-01

    This field study examines the joint effects of social exchange relationships at work (leader-member exchange and team-member exchange) and employee personality (conscientiousness and agreeableness) in predicting task performance and citizenship performance. Consistent with trait activation theory, matched data on 230 employees, their coworkers, and their supervisors demonstrated interactions in which high quality social exchange relationships weakened the positive relationships between personality and performance. Results demonstrate the benefits of consonant predictions in which predictors and outcomes are matched on the basis of specific targets. We discuss theoretical and practical implications. (c) 2007 APA.

  14. Performance of a counterflow heat exchanger with heat loss through the wall at the cold end

    Energy Technology Data Exchange (ETDEWEB)

    Narayanan, S.P.; Venkatarathnam, G. [Indian Institute of Technology, Chennai (India). Dept. of Mechanical Engineering

    1999-11-01

    The performance of high effectiveness heat exchangers used in cryogenic systems is strongly controlled by irreversibilities such as longitudinal heat conduction and heat leak from ambient. In all heat exchanger analyses, it is assumed that no heat is lost through the heat exchanger walls. In the case of small J-T refrigerators such as microminiature refrigerators, the heat exchanger cold end is almost directly connected to the evaporator, which may result in a large amount of heat loss through the heat exchanger wall at the cold end. The rate of heat loss through the wall at the cold end is also strongly dependent on the longitudinal thermal resistance of the wall. In this paper, we present the relationship between the effectiveness of a heat exchanger losing heat at the cold end and other resistances such as number of transfer units (NTU), longitudinal thermal resistance etc. The performance of such heat exchangers under different operating conditions is also discussed. (author)

  15. Development and Evaluation of Photoprotective O/W Emulsions Containing Hydroalcoholic Extract of Neoglaziovia variegata (Bromeliaceae).

    Science.gov (United States)

    de Oliveira-Júnior, Raimundo Gonçalves; Souza, Grasielly Rocha; Ferraz, Christiane Adrielly Alves; de Oliveira, Ana Paula; Araújo, Camila de Souza; de Lima-Saraiva, Sarah Raquel Gomes; Reis, Silvio Alan Gonçalves Bomfim; Gonçalves, Talita Mota; Rolim, Larissa Araújo; Rolim-Neto, Pedro José; César, Francine Celise Siqueira; Almeida, Jackson Roberto Guedes da Silva

    2017-01-01

    Neoglaziovia variegata is a Bromeliaceae plant species widely found in Brazil with several pharmacological properties, including photoprotective activity. Although herbal-based active ingredients have been applied in cosmetic products, especially for skin treatment, its application in sunscreen formulations remains unexplored. The aim of this work is to evaluate the photoprotective effect of cosmetic formulations containing hydroalcoholic extract of N. variegata (Nv-HA). Initially, the phenolic and flavonoid total content of Nv-HA were determined. The photoprotective activity of Nv-HA was subsequently assessed using a spectrophotometric method. Nv-HA was incorporated in O/W emulsions in the presence or absence of synthetic filters and their photoprotective efficacy was evaluated by spectrophotometric SPF determination. Finally, the stability study of the formulations was performed through the freezing/defrosting method. Nv-HA showed significant phenolic and flavonoids content (61.66 ± 5.14 mg GAE/g and 90.27 ± 5.03 mg CE/g, resp.). Nv-HA showed SPF values of 5.43 ± 0.07 and 11.73 ± 0.04 for the concentrations of 0.5 and 1.0% (v/v), respectively. It was verified that Nv-HA potentiated the photoprotective effect of formulations containing only synthetic filters. Furthermore, the formulations have remained stable at the end of the preliminary stability study. According to the results, it was concluded that Nv-HA can be used as a chemical filter in cosmetic formulations.

  16. Development and Evaluation of Photoprotective O/W Emulsions Containing Hydroalcoholic Extract of Neoglaziovia variegata (Bromeliaceae

    Directory of Open Access Journals (Sweden)

    Raimundo Gonçalves de Oliveira-Júnior

    2017-01-01

    Full Text Available Neoglaziovia variegata is a Bromeliaceae plant species widely found in Brazil with several pharmacological properties, including photoprotective activity. Although herbal-based active ingredients have been applied in cosmetic products, especially for skin treatment, its application in sunscreen formulations remains unexplored. The aim of this work is to evaluate the photoprotective effect of cosmetic formulations containing hydroalcoholic extract of N. variegata (Nv-HA. Initially, the phenolic and flavonoid total content of Nv-HA were determined. The photoprotective activity of Nv-HA was subsequently assessed using a spectrophotometric method. Nv-HA was incorporated in O/W emulsions in the presence or absence of synthetic filters and their photoprotective efficacy was evaluated by spectrophotometric SPF determination. Finally, the stability study of the formulations was performed through the freezing/defrosting method. Nv-HA showed significant phenolic and flavonoids content (61.66±5.14 mg GAE/g and 90.27±5.03 mg CE/g, resp.. Nv-HA showed SPF values of 5.43±0.07 and 11.73±0.04 for the concentrations of 0.5 and 1.0% (v/v, respectively. It was verified that Nv-HA potentiated the photoprotective effect of formulations containing only synthetic filters. Furthermore, the formulations have remained stable at the end of the preliminary stability study. According to the results, it was concluded that Nv-HA can be used as a chemical filter in cosmetic formulations.

  17. Development and Evaluation of Photoprotective O/W Emulsions Containing Hydroalcoholic Extract of Neoglaziovia variegata (Bromeliaceae)

    Science.gov (United States)

    Souza, Grasielly Rocha; Ferraz, Christiane Adrielly Alves; de Oliveira, Ana Paula; Araújo, Camila de Souza; de Lima-Saraiva, Sarah Raquel Gomes; Gonçalves, Talita Mota; Rolim-Neto, Pedro José; César, Francine Celise Siqueira

    2017-01-01

    Neoglaziovia variegata is a Bromeliaceae plant species widely found in Brazil with several pharmacological properties, including photoprotective activity. Although herbal-based active ingredients have been applied in cosmetic products, especially for skin treatment, its application in sunscreen formulations remains unexplored. The aim of this work is to evaluate the photoprotective effect of cosmetic formulations containing hydroalcoholic extract of N. variegata (Nv-HA). Initially, the phenolic and flavonoid total content of Nv-HA were determined. The photoprotective activity of Nv-HA was subsequently assessed using a spectrophotometric method. Nv-HA was incorporated in O/W emulsions in the presence or absence of synthetic filters and their photoprotective efficacy was evaluated by spectrophotometric SPF determination. Finally, the stability study of the formulations was performed through the freezing/defrosting method. Nv-HA showed significant phenolic and flavonoids content (61.66 ± 5.14 mg GAE/g and 90.27 ± 5.03 mg CE/g, resp.). Nv-HA showed SPF values of 5.43 ± 0.07 and 11.73 ± 0.04 for the concentrations of 0.5 and 1.0% (v/v), respectively. It was verified that Nv-HA potentiated the photoprotective effect of formulations containing only synthetic filters. Furthermore, the formulations have remained stable at the end of the preliminary stability study. According to the results, it was concluded that Nv-HA can be used as a chemical filter in cosmetic formulations. PMID:28680948

  18. Ion exchange performance of commercial crystalline silicotitanates for cesium removal

    Energy Technology Data Exchange (ETDEWEB)

    Braun, R.; Dangieri, T.J.; Fennelly, D.J. [and others

    1996-03-01

    A new class of inorganic ion exchangers called crystalline silicotitanates (CST), invented by researchers at Sandia National Laboratories and Texas A&M University, has been commercialized in a joint Sandia-UOP effort. The original developmental materials exhibited high selectivity for the ion exchange of cesium, strontium, and several other radionuclides from highly alkaline solutions containing molar concentrations of Na{sup +}. The materials also showed excellent chemical and radiation stability. Together, the high selectivity and stability of the CSTs made them excellent candidates for treatment of solutions such as the Hanford tank supernates and other DOE radwastes. Sandia National Laboratories and UOP have teamed under a Cooperative Research and Development Agreement (CRADA) to develop CSTs in the powdered form and in an engineered form suitable for column ion exchange use. A continuous-flow, column ion exchange process is expected to be used to remove Cs and other radionuclides from the Hanford supernatant. The powder material invented by the Sandia and Texas A&M team consists of submicron-size particles. It is not designed for column ion exchange but may be used in other applications.

  19. Photoprotection: part II. Sunscreen: development, efficacy, and controversies.

    Science.gov (United States)

    Jansen, Rebecca; Osterwalder, Uli; Wang, Steven Q; Burnett, Mark; Lim, Henry W

    2013-12-01

    In addition to the naturally occurring, physical, and systemic photoprotective agents reviewed in part I, topical ultraviolet radiation filters are an important cornerstone of photoprotection. Sunscreen development, efficacy, testing, and controversies are reviewed in part II of this continuing medical education article. Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  20. Influence of the Water-Cooled Heat Exchanger on the Performance of a Pulse Tube Refrigerator

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-02-01

    Full Text Available The water-cooled heat exchanger is one of the key components in a pulse tube refrigerator. Its heat exchange effectiveness directly influences the cooling performance of the refrigerator. However, effective heat exchange does not always result in a good performance, because excessively reinforced heat exchange can lead to additional flow loss. In this paper, seven different water-cooled heat exchangers were designed to explore the best configuration for a large-capacity pulse tube refrigerator. Results indicated that the heat exchanger invented by Hu always offered a better performance than that of finned and traditional shell-tube types. For a refrigerator with a working frequency of 50 Hz, the best hydraulic diameter is less than 1 mm.

  1. Melanogenesis: a photoprotective response to DNA damage?

    Energy Technology Data Exchange (ETDEWEB)

    Agar, Nita [St. John' s Institute of Dermatology, Guy' s, Kings and St. Thomas' School of Medicine, Kings College London, London (United Kingdom); Young, Antony R. [St. John' s Institute of Dermatology, Guy' s, Kings and St. Thomas' School of Medicine, Kings College London, London (United Kingdom)]. E-mail: antony.r.young@kcl.ac.uk

    2005-04-01

    Exposure to ultra violet radiation (UVR) is associated with significant long-term deleterious effects such as skin cancer. A well-recognised short-term consequence of UVR is increased skin pigmentation. Pigmentation, whether constitutive or facultative, has widely been viewed as photoprotective, largely because darkly pigmented skin is at a lower risk of photocarcinogenesis than fair skin. Research is increasingly suggesting that the relationship between pigmentation and photoprotection may be far more complex than previously assumed. For example, photoprotection against erythema and DNA damage has been shown to be independent of level of induced pigmentation in human white skin types. Growing evidence now suggests that UVR induced DNA photodamage, and its repair is one of the signals that stimulates melanogenesis and studies suggest that repeated exposure in skin type IV results in faster DNA repair in comparison to skin type II. These findings suggest that tanning may be a measure of inducible DNA repair capacity, and it is this rather than pigment per se which results in the lower incidence skin cancer observed in darker skinned individuals. This evokes the notion that epidermal pigmentation may in fact be the mammalian equivalent of a bacterial SOS response. Skin colour is one of most conspicuous ways in which humans vary yet the function of melanin remains controversial. Greater understanding of the role of pigmentation in skin is vital if one is to be able to give accurate advice to the general public about both the population at risk of skin carcinogenesis and also public perceptions of a tan as being healthy.

  2. Comparative field performance of three different gas exchange systems

    Directory of Open Access Journals (Sweden)

    G. F. Midgley

    1997-12-01

    Full Text Available We compared portable and continuously monitoring gas exchange systems under field conditions, using Protea glabra Thunb. as a test species. The aim was to determine if the same patterns of gas exchange and ancillary parameters could be obtained with rather different measurement systems, and whether the same interpretation and conclusions about environmental control of gas exchange could be drawn. The following systems were compared: 1, a ‘closed’ portable 1RGA manufactured by Ll-Cor (LI-6200; 2, an ‘open’ portable porometer manufactured by Walz; and 3, a continuously monitoring minicuvette system with temperature control facility, also manufactured by Walz. All three systems yielded similar diurnal curves for CO2  uptake, although absolute flux values for the minicuvette system were lower than those obtained for the portable systems. This was likely due to stem respiration and self-shading of leaves on the shoot enclosed in the minicuvette. Differences in sampling technique between the two portable systems, primarily with regard to changes in leaf orientation, resulted in some differences in absolute values of gas fluxes and ancillary parameters such as leaf temperature and leaf to air vapour pressure difference. However, data from all three systems allowed similar interpretations to be made about the environmental dependencies of gas exchange patterns. It appears that each system has certain drawbacks associated with widely varying field conditions. A combination of portable and continuous monitoring techniques would seem to be the most powerful approach to investigating the gas exchange patterns of terrestrial plants in their natural environment.

  3. DNA dosimetry assessment for sunscreen genotoxic photoprotection.

    Directory of Open Access Journals (Sweden)

    André Passaglia Schuch

    Full Text Available BACKGROUND: Due to the increase of solar ultraviolet radiation (UV incidence over the last few decades, the use of sunscreen has been widely adopted for skin protection. However, considering the high efficiency of sunlight-induced DNA lesions, it is critical to improve upon the current approaches that are used to evaluate protection factors. An alternative approach to evaluate the photoprotection provided by sunscreens against daily UV radiation-induced DNA damage is provided by the systematic use of a DNA dosimeter. METHODOLOGY/PRINCIPAL FINDINGS: The Sun Protection Factor for DNA (DNA-SPF is calculated by using specific DNA repair enzymes, and it is defined as the capacity for inhibiting the generation of cyclobutane pyrimidine dimers (CPD and oxidised DNA bases compared with unprotected control samples. Five different commercial brands of sunscreen were initially evaluated, and further studies extended the analysis to include 17 other products representing various formulations and Sun Protection Factors (SPF. Overall, all of the commercial brands of SPF 30 sunscreens provided sufficient protection against simulated sunlight genotoxicity. In addition, this DNA biosensor was useful for rapidly screening the biological protection properties of the various sunscreen formulations. CONCLUSIONS/SIGNIFICANCE: The application of the DNA dosimeter is demonstrated as an alternative, complementary, and reliable method for the quantification of sunscreen photoprotection at the level of DNA damage.

  4. Photoprotection strategies of the alga Nannochloropsis gaditana.

    Science.gov (United States)

    Chukhutsina, Volha U; Fristedt, Rikard; Morosinotto, Tomas; Croce, Roberta

    2017-07-01

    Nannochloropsis spp. are algae with high potential for biotechnological applications due to their capacity to accumulate lipids. However, little is known about their photosynthetic apparatus and acclimation/photoprotective strategies. In this work, we studied the mechanisms of non-photochemical quenching (NPQ), the fast response to high light stress, in Nannochloropsis gaditana by "locking" the cells in six different states during quenching activation and relaxation. Combining biochemical analysis with time-resolved fluorescence spectroscopy, we correlated each NPQ state with the presence of two well-known NPQ components: de-epoxidized xanthophylls and stress-related antenna proteins (LHCXs). We demonstrated that after exposure to strong light, the rapid quenching that takes place in the antennas of both photosystems was associated with the presence of LHCXs. At later stages, quenching occurs mainly in the antennas of PSII and correlates with the amount of de-epoxidised xanthophylls. We also observed changes in the distribution of excitation energy between photosystems, which suggests redistribution of excitation between photosystems as part of the photo-protective strategy. A multistep model for NPQ induction and relaxation in N. gaditana is discussed. Copyright © 2017. Published by Elsevier B.V.

  5. DNA Dosimetry Assessment for Sunscreen Genotoxic Photoprotection

    Science.gov (United States)

    Schuch, André Passaglia; Lago, Juliana Carvalhães; Yagura, Teiti; Menck, Carlos Frederico Martins

    2012-01-01

    Background Due to the increase of solar ultraviolet radiation (UV) incidence over the last few decades, the use of sunscreen has been widely adopted for skin protection. However, considering the high efficiency of sunlight-induced DNA lesions, it is critical to improve upon the current approaches that are used to evaluate protection factors. An alternative approach to evaluate the photoprotection provided by sunscreens against daily UV radiation-induced DNA damage is provided by the systematic use of a DNA dosimeter. Methodology/Principal Findings The Sun Protection Factor for DNA (DNA-SPF) is calculated by using specific DNA repair enzymes, and it is defined as the capacity for inhibiting the generation of cyclobutane pyrimidine dimers (CPD) and oxidised DNA bases compared with unprotected control samples. Five different commercial brands of sunscreen were initially evaluated, and further studies extended the analysis to include 17 other products representing various formulations and Sun Protection Factors (SPF). Overall, all of the commercial brands of SPF 30 sunscreens provided sufficient protection against simulated sunlight genotoxicity. In addition, this DNA biosensor was useful for rapidly screening the biological protection properties of the various sunscreen formulations. Conclusions/Significance The application of the DNA dosimeter is demonstrated as an alternative, complementary, and reliable method for the quantification of sunscreen photoprotection at the level of DNA damage. PMID:22768281

  6. ZEOLITE PERFORMANCE AS AN ANION EXCHANGER FOR ARSENIC SEQUESTRATION IN WATER

    Science.gov (United States)

    Zeolites are well known for their use in ion exchange and acid catalysis reactions. The use of zeolites in anion or ligand exchange reactions is less studied. The NH4+ form of zeolite Y (NY6, Faujasite) has been tested in this work to evaluate its performance for arsenic removal...

  7. Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness

    Science.gov (United States)

    Andrzejczyk, Rafał; Muszyński, Tomasz

    2016-12-01

    The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow inside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.

  8. In vitro photoprotective effects of Marcetia taxifolia ethanolic extract and its potential for sunscreen formulations

    Directory of Open Access Journals (Sweden)

    Sônia C.C. Costa

    Full Text Available AbstractThe species Marcetia taxifolia (A. St.-Hil. DC., Melastomataceae, which is endemic of the rupestrian fields of northeastern Brazil, contains a significant amount of flavonoids. In this work, the potential of the ethanolic extract of M. taxifolia as the active principle in a sunscreen photoprotection (UV-A and UV-B formulation was investigated. The Liquid Chromatography High Performance-Diode Array Detector quantification (quercetin, total flavonoid content, antioxidant activity through 2.2-diphenyl-1- picrylhydrazil method, photoprotective activity against UV-B and UV-A radiation in vitro (spectrophotometric method and potential for eye irritation using the methodology of the hen egg test-chorioallantoic membrane were performed in the extract. After that, the formulations were prepared using different concentrations of active ethanolic extract (5, 10, 20 and 30% and the evaluation of the sun protection factor was carried out using the same methodology used for the crude extract. The crude extract showed UV-A photoprotection and low eye irritation in the hen egg test-chorioallantoic membrane test. All formulations containing M. taxifolia extract had ≥ 6 sun protection factor. Its shows the possibility to use this extracts as a sunscreen in pharmaceutical preparations.

  9. Photoprotection in Plants Optical Screening-based Mechanisms

    CERN Document Server

    Solovchenko, Alexei

    2010-01-01

    Optical screening of excessive and potentially harmful solar radiation is an important photoprotective mechanism, though it has received much less attention in comparison with other systems preventing photooxidative damage to photoautotrophic organisms. This photoprotection in the form of screening appears to be especially important for juvenile and senescing plants as well as under environmental stresses—i.e. in situations where the efficiency of enzymatic ROS elimination, DNA repair and other ‘classical’ photoprotective systems could be impaired. This book represents an attempt to develop an integral view of optical screening-based photoprotection in microalgae and higher plants. Towards this end, the key groups of pigments involved in the screening of ultraviolet and visible components of solar radiation in microalgae and higher plants, and the patterns of their accumulation and distribution within plant cells and tissues, are described. Special attention is paid to the manifestations of screening pi...

  10. Performance of multiple mini-tube heat exchangers as an internal heat exchanger of a vapor-injection cycle heat pump

    Science.gov (United States)

    Jang, Jin Yong; Jeong, Ji Hwan

    2016-04-01

    A multiple mini-tube (MMT) heat exchanger was considered as an internal heat exchanger of vapor-injection cycle heat pump. Heat transfer and pressure drop in multiple mini-tube heat exchangers were numerically and experimentally investigated. Results show that the best performance of the MMT heat exchanger can be obtained when the intermediate-pressure two-phase refrigerant is supplied to the shell-side and this refrigerant reaches a saturated vapor state at the exit of the heat exchanger.

  11. Polyphenols: Skin Photoprotection and Inhibition of Photocarcinogenesis

    Science.gov (United States)

    Afaq, Farrukh; Katiyar, Santosh K.

    2011-01-01

    Polyphenols are a large family of naturally occurring plant products and are widely distributed in plant foods, such as, fruits, vegetables, nuts, flowers, bark and seeds, etc. These polyphenols contribute to the beneficial health effects of dietary products. Clinical and epidemiological studies suggest that exposure of the skin to environmental factors/pollutants, such as solar ultraviolet (UV) radiation induce harmful effects and leads to various skin diseases including the risk of melanoma and non-melanoma skin cancers. The incidence of non-melanoma skin cancer, comprising of squamous cell carcinoma and basal cell carcinoma, is a significant public health concern world-wide. Exposure of the skin to solar UV radiation results in inflammation, oxidative stress, DNA damage, dysregulation of cellular signaling pathways and immunosuppression thereby resulting in skin cancer. The regular intake of natural plant products, especially polyphenols, which are widely present in fruits, vegetables, dry legumes and beverages have gained considerable attention as protective agents against the adverse effects of UV radiation. In this article, we first discussed the impact of polyphenols on human health based on their structure-activity relationship and bioavailability. We then discussed in detail the photoprotective effects of some selected polyphenols on UV-induced skin inflammation, proliferation, immunosuppression, DNA damage and dysregulation of important cellular signaling pathways and their implications in skin cancer management. The selected polyphenols include: green tea polyphenols, pomegranate fruit extract, grape seed proanthocyanidins, resveratrol, silymarin, genistein and delphinidin. The new information on the mechanisms of action of these polyphenols supports their potential use in skin photoprotection and prevention of photocarcinogenesis in humans. PMID:22070679

  12. Photoprotection of photosystems in fluctuating light intensities.

    Science.gov (United States)

    Allahverdiyeva, Yagut; Suorsa, Marjaana; Tikkanen, Mikko; Aro, Eva-Mari

    2015-05-01

    Oxygenic photosynthetic organisms experience strong fluctuations in light intensity in their natural terrestrial and aquatic growth environments. Recent studies with both plants and cyanobacteria have revealed that Photosystem (PS) I is the potential target of damage upon abrupt changes in light intensity. Photosynthetic organisms have, however, developed powerful mechanisms in order to protect their photosynthetic apparatus against such potentially hazardous light conditions. Although the electron transfer chain has remained relatively unchanged in both plant chloroplasts and their cyanobacterial ancestors, the photoprotective and regulatory mechanisms of photosynthetic light reactions have experienced conspicuous evolutionary changes. In cyanobacteria, the specific flavodiiron proteins (Flv1 and Flv3) are responsible for safeguarding PSI under rapidly fluctuating light intensities, whilst the thylakoid located terminal oxidases are involved in the protection of PSII during 12h diurnal cycles involving abrupt, square-wave, changes from dark to high light. Higher plants such as Arabidopsis thaliana have evolved different protective mechanisms. In particular, the PGR5 protein controls electron flow during sudden changes in light intensity by allowing the regulation mostly via the Cytochrome b6f complex. Besides the function of PGR5, plants have also acquired other dynamic regulatory mechanisms, among them the STN7-related LHCII protein phosphorylation that is similarly responsible for protection against rapid changes in the light environment. The green alga Chlamydomonas reinhardtii, as an evolutionary intermediate between cyanobacteria and higher plants, probably possesses both protective mechanisms. In this review, evolutionarily different photoprotective mechanisms under fluctuating light conditions are described and their contributions to cyanobacterial and plant photosynthesis are discussed. © The Author 2014. Published by Oxford University Press on behalf of

  13. Thermal performance of direct contact heat exchangers for mixed hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Sharpe, L. Jr.; Coswami, D.Y.; Demuth, O.J.; Mines, G.

    1985-01-01

    This paper describes a physical and a mathematical model for evaluating the tray efficiencies for a direct contact heat exchanger (DCHX). The model is then used to determine the efficiencies for tests conducted on a 60kW sieve tray DCHX as heat is transferred from a geofluid (brine) to a working fluid (mixed hydrocarbons). It is assumed that there are three distinct regions in the column based on the state of the working fluid, as follows: Region I - Preheating with no vaporization; Region II - Preheating with moderate vaporization; and Region III - Major vaporization. The boundaries of these regions can be determined from the experimental data. In the model, mass balance and energy balance is written for a tray ''N'' in each of these regions. Finally, the ''tray efficiency'' or ''heat transfer'' effectiveness of the tray is calculated based on the definition that it is the ratio of the actual heat transfer to the maximum possible, thermodynamically.

  14. Performance enhancement study of mobile air conditioning system using microchannel heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Zhaogang; Zhao, Yu.; Chen, Jiangping [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai 200240 (China)

    2010-03-15

    In the present paper, two retrofitted compact and high efficient microchannel heat exchangers were proposed. The new microchannel heat exchangers have advantages in compactness (17.2% and 15.1% volume reduction for evaporator and condenser, respectively), weight (2.8% and 14.9% lighter for evaporator and condenser, respectively), heat transfer characteristics compared with the currently used heat exchangers in mobile air conditioning (MAC) industry. One enhanced and one baseline R134a MAC systems were established including the new microchannel heat exchangers and the traditional MAC heat exchangers, respectively. The system performances have been experimentally carried out under variable ambient conditions in psychrometric calorimeter test bench. The optimal system refrigerant charge amounts for both systems were tested and the results showed that the enhanced system with more compact heat exchangers could reduce system charge amount and the minimum effective charge amount was less than that of the baseline system. The enhanced system could supply more cooling capacity to car compartment under all test conditions because of higher performance heat exchangers. The coefficient of performance (COP) of the enhanced system was slightly lower than that of the baseline system under idle conditions but higher under all the other test conditions. Cooling capacity and COP of the enhanced system was increased by about 5% and 8% under high vehicle speed condition. (author)

  15. Air to air fixed plate enthalpy heat exchanger, performance variation and energy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nasif, Mohammad Shakir [Universiti Teknologi Petronas, Bandar Seri Iskandar (Malaysia); Alwaked, Rafat [Prince Mohammad Bin Fahd University, Al Khobar (Saudi Arabia); Behnia, Masud [University of Sydney, Sydney (Australia); Morrison, Graham [The University of New South Wales, Sydney (Australia)

    2013-11-15

    The thermal performance of a Z shape enthalpy heat exchanger utilising 70 gsm Kraft paper as the heat and moisture transfer surface has been investigated. Effects of different inlet air humidity ratio conditions on the heat exchanger effectiveness and on the energy recovered by the heat exchanger have been the main focus of this investigation. A typical air conditioning cooling coil which incorporates an enthalpy heat exchanger has been modelled for tropical climate. Under test conditions, results have shown that latent effectiveness and the moisture resistance coefficient have strong dependency on the inlet air humidity ratio. Moreover, the latent effectiveness has been found to be strongly dependent on the moisture resistance coefficient rather than the convective mass transfer coefficient. Finally, annual energy analysis for Singapore weather conditions have also shown that energy recovered under variable inlet air conditions is 15% less than that recovered under constant inlet air conditions for the same heat exchanger.

  16. Single-molecule exploration of photoprotective mechanisms in light-harvesting complexes

    Science.gov (United States)

    Yang, Hsiang-Yu; Schlau-Cohen, Gabriela S.; Gwizdala, Michal; Krüger, Tjaart; Xu, Pengqi; Croce, Roberta; van Grondelle, Rienk; Moerner, W. E.

    2015-03-01

    Plants harvest sunlight by converting light energy to electron flow through the primary events in photosynthesis. One important question is how the light harvesting machinery adapts to fluctuating sunlight intensity. As a result of various regulatory processes, efficient light harvesting and photoprotection are balanced. Some of the biological steps in the photoprotective processes have been extensively studied and physiological regulatory factors have been identified. For example, the effect of lumen pH in changing carotenoid composition has been explored. However, the importance of photophysical dynamics in the initial light-harvesting steps and its relation to photoprotection remain poorly understood. Conformational and excited-state dynamics of multi-chromophore pigment-protein complexes are often difficult to study and limited information can be extracted from ensemble-averaged measurements. To address the problem, we use the Anti-Brownian ELectrokinetic (ABEL) trap to investigate the fluorescence from individual copies of light-harvesting complex II (LHCII), the primary antenna protein in higher plants, in a solution-phase environment. Perturbative surface immobilization or encapsulation schemes are avoided, and therefore the intrinsic dynamics and heterogeneity in the fluorescence of individual proteins are revealed. We perform simultaneous measurements of fluorescence intensity (brightness), excited-state lifetime, and emission spectrum of single trapped proteins. By analyzing the correlated changes between these observables, we identify forms of LHCII with different fluorescence intensities and excited-state lifetimes. The distinct forms may be associated with different energy dissipation mechanisms in the energy transfer chain. Changes of relative populations in response to pH and carotenoid composition are observed, which may extend our understanding of the molecular mechanisms of photoprotection.

  17. Diurnal Solar Energy Conversion and Photoprotection in Rice Canopies1[OPEN

    Science.gov (United States)

    Quick, W. Paul; von Caemmerer, Susanne; Furbank, Robert

    2017-01-01

    Genetic improvement of photosynthetic performance of cereal crops and increasing the efficiency with which solar radiation is converted into biomass has recently become a major focus for crop physiologists and breeders. The pulse amplitude modulated chlorophyll fluorescence technique (PAM) allows quantitative leaf level monitoring of the utilization of energy for photochemical light conversion and photoprotection in natural environments, potentially over the entire crop lifecycle. Here, the diurnal relationship between electron transport rate (ETR) and irradiance was measured in five cultivars of rice (Oryza sativa) in canopy conditions with PAM fluorescence under natural solar radiation. This relationship differed substantially from that observed for conventional short term light response curves measured under controlled actinic light with the same leaves. This difference was characterized by a reduced curvature factor when curve fitting was used to model this diurnal response. The engagement of photoprotective processes in chloroplast electron transport in leaves under canopy solar radiation was shown to be a major contributor to this difference. Genotypic variation in the irradiance at which energy flux into photoprotective dissipation became greater than ETR was observed. Cultivars capable of higher ETR at midrange light intensities were shown to produce greater leaf area over time, estimated by noninvasive imaging. PMID:27895208

  18. Prototype Vent Gas Heat Exchanger for Exploration EVA - Performance and Manufacturing Characteristics

    Science.gov (United States)

    Quinn, Gregory J.; Strange, Jeremy; Jennings, Mallory

    2013-01-01

    NASA is developing new portable life support system (PLSS) technologies, which it is demonstrating in an unmanned ground based prototype unit called PLSS 2.0. One set of technologies within the PLSS provides suitable ventilation to an astronaut while on an EVA. A new component within the ventilation gas loop is a liquid-to-gas heat exchanger to transfer excess heat from the gas to the thermal control system s liquid coolant loop. A unique bench top prototype heat exchanger was built and tested for use in PLSS 2.0. The heat exchanger was designed as a counter-flow, compact plate fin type using stainless steel. Its design was based on previous compact heat exchangers manufactured by United Technologies Aerospace Systems (UTAS), but was half the size of any previous heat exchanger model and one third the size of previous liquid-to-gas heat exchangers. The prototype heat exchanger was less than 40 cubic inches and weighed 2.57 lb. Performance of the heat exchanger met the requirements and the model predictions. The water side and gas side pressure drops were less 0.8 psid and 0.5 inches of water, respectively, and an effectiveness of 94% was measured at the nominal air side pressure of 4.1 psia.

  19. Justice, leader-member exchange, and job performance: are their relationships mediated by organizational culture?

    Science.gov (United States)

    Tziner, Aharon; Shultz, Tamar; Fisher, Tom

    2008-10-01

    The hypothesis that organizational justice is linked to leader-member exchange, which in turn affects job performance, was examined. It was predicted that two dimensions of organizational culture, employee supportiveness and attention to detail, would affect both leader-member exchange and organizational justice. Results from a sample of 75 employees of a public service organization found solid support for the predicted model. Contrary to expectations, however, the two aspects of organizational culture were found to play a mediating role: they were affected by organizational justice and in turn affected leader-member exchange. The theoretical implications of the results are discussed.

  20. Impacts of Exchange Rate Regime Choice on Macroeconomic Performance in Emerging Markets

    Directory of Open Access Journals (Sweden)

    Rüstem Yanar

    2008-12-01

    Full Text Available This paper investigates the impact of exchange rate regime choice on macroeconomic performance after Bretton Woods in emerging market countries. It is studied especially inflation, growth and financial crises. It’s found that for emerging market countries, fixed regimes are associated with lower inflation than floats. On growth effect of exchange rate regime choice is not same all period. Fixed regimes are associated with faster growth but after 1990 fixed regimes brought about slower growth. At the same time, fixed exchange rate regimes are associated with financial fragility after 1990 in emerging markets

  1. Membrane-type Total Heat Exchanger Performance Simulation with Consideration of Entrance Effects

    Science.gov (United States)

    Duan, J. F.; Min, J. C.

    2017-11-01

    Membrane-type total heat exchanger (THX) is an air-to-air heat exchanger used to reduce the building energy consumption associated with forced ventilation by recovering both heat and moisture from ventilation air. It contains a heat/moisture exchange core made of a water vapour permeable membrane, supply outdoor air and exhaust indoor air flow through the membrane channels in the core in a crossflow manner and exchange heat and moisture across the membranes. The present work numerically investigates the airflow channel entrance effects on the THX performance. The results show that such effects on the air temperature and humidity distributions are inconspicuous and so are they on the THX effectiveness, it is therefore appropriate to use the constant Nusselt number to evaluate the THX performance.

  2. Subjective trust, perceived risk and exchange performance in buyer-supplier relationships

    OpenAIRE

    Emanuela Delbufalo

    2012-01-01

    This article offers some theoretical and empirical contributions to the literature on relational exchange by examining the nature of subjective trust and perceived risk in buyer-supplier relationships. The relational view represents the theoretical framework for the research. The study explores the theoretical proposition that subjective trust and perceived risk in buyer-supplier relationships impact on exchange performance through the mediating effects of four sources of relational rents: as...

  3. Home Performance with ENERGY STAR(R) Exchange

    Energy Technology Data Exchange (ETDEWEB)

    2003-10-01

    Handout for the Energy and Environmental Building Association's Building Solutions 2003 Conference and Expo: Chicago, Illinois, October 2003 The following summaries, provided by implementers of ''Home Performance with ENERGY STAR{reg_sign}'' around the country, are for use in the October 15 discussion during the Energy & Environmental Building Association (EEBA) Building Solutions, 2003 Conference in Chicago. The summaries and session discussions provide an overview of ''Home Performance with ENERGY STAR'', along with results and lessons learned from existing ''Home Performance'' implementers in New York, Wisconsin, Massachusetts, California, and Kansas City. Five future pilot projects set to begin in Georgia/Alabama, Idaho, Missouri, New Jersey and Texas will also be presented and discussed. Session topics will include the use of different training approaches, methods of quality assurance, and the role contractor certification plays in several of the programs. The session will conclude with a roundtable discussion of Home Performance issues by current and emerging implementers, with time for participant questions. ''Home Performance with ENERGY STAR'' uses the growing awareness and credibility of the ENERGY STAR brand to encourage and facilitate whole-house energy improvements in existing homes through self-sustaining energy efficiency programs. Whether you're a state energy official, utility program manager, contractor training professional or efficiency program implementer, you're sure to benefit from the unique presentations and networking opportunities that this session will offer.

  4. A novel, simplified ex vivo method for measuring water exchange performance of heat and moisture exchangers for tracheostomy application.

    Science.gov (United States)

    van den Boer, Cindy; Muller, Sara H; Vincent, Andrew D; Züchner, Klaus; van den Brekel, Michiel W M; Hilgers, Frans J M

    2013-09-01

    Breathing through a tracheostomy results in insufficient warming and humidification of inspired air. This loss of air-conditioning can be partially compensated for with the application of a heat and moisture exchanger (HME) over the tracheostomy. In vitro (International Organization for Standardization [ISO] standard 9360-2:2001) and in vivo measurements of the effects of an HME are complex and technically challenging. The aim of this study was to develop a simple method to measure the ex vivo HME performance comparable with previous in vitro and in vivo results. HMEs were weighed at the end of inspiration and at the end of expiration at different breathing volumes. Four HMEs (Atos Medical, Hörby, Sweden) with known in vivo humidity and in vitro water loss values were tested. The associations between weight change, volume, and absolute humidity were determined using both linear and non-linear mixed effects models. The rating between the 4 HMEs by weighing correlated with previous intra-tracheal measurements (R(2) = 0.98), and the ISO standard (R(2) = 0.77). Assessment of the weight change between end of inhalation and end of exhalation is a valid and simple method of measuring the water exchange performance of an HME.

  5. Contrasting phenotypic plasticity in the photoprotective strategies of the invasive species Carpobrotus edulis and the coexisting native species Crithmum maritimum.

    Science.gov (United States)

    Fenollosa, Erola; Munné-Bosch, Sergi; Pintó-Marijuan, Marta

    2017-06-01

    Photoprotective strategies vary greatly within the plant kingdom and reflect a plant's physiological status and capacity to cope with environment variations. The plasticity and intensity of these responses may determine plant success. Invasive species are reported to show increased vigor to displace native species. Describing the mechanisms that confer such vigor is essential to understanding the success of invasive species. We performed an experiment whereby two species were monitored: Carpobrotus edulis, an aggressive invasive species in the Mediterranean basin, and Crithmum maritimum, a coexisting native species in the Cap de Creus Natural Park (NE Spain). We analyzed their photoprotective responses to seasonal environmental dynamics by comparing the capacity of the invader to respond to the local environmental stresses throughout the year. Our study analyses ecophysiological markers and photoprotective strategies to gain an insight into the success of invaders. We found that both species showed completely different but effective photoprotective strategies: in summer, C. edulis took special advantage of the xanthophyll cycle, whereas the success of C. maritimum in summer stemmed from morphological changes and alterations on β-carotene content. Winter also presented differences between the species, as the native showed reduced Fv /Fm ratios. Our experimental design allowed us to introduce a new approach to compare phenotypic plasticity: the integrated phenotypic plasticity index (PPint ), defined as the maximum Euclidian distance between phenotypes, using a combination of different variables to describe them. This index revealed significantly greater phenotypic plasticity in the invasive species compared to the native species. © 2017 Scandinavian Plant Physiology Society.

  6. [Polymorphic light dermatitis. Photobiology and photoprotection].

    Science.gov (United States)

    Corrales Padilla, H

    1976-01-01

    It is possible in the majority of patients with polymorphic light eruption to produce lesions experimentally. Only the reproduction of the clinical reaction is significant for the diagnosis. Irradiation is carried out in the same test area two or three times with a dose of up to eight times the minimal erythema dose. Sunlight is the best agent for the evaluation of this protocutaneous disorder. A localised area of the skin can be exposed to midday sunshine about half an hour on three consecutive days. But sunlight has the disadvantage of having a variable ultraviolet emission at different times. It is necessary to differentiate lupus erythematosus and photocontact dermatitis, which may produce identical reactions. Other light sources are the hot quartz lamp, fluorescent tube "sun lamp", solar simulator and the monochromater. Patients with polymorphic light eruption are sensitive to light in the range 300 to 320 nm. but some of them are sensitive to savelengths shorter or longer than this range. The methods of protection against solar radiation which have been tried include: 1) Avoidance of sunlight; 2) Promotion of melanin hyperpgimentation and thickening of the stratum corneum-by controlled exposure to sunlight; 3) Application of a film of a chemical compound that will act as a physical screen and absorb, scatter or reflect damaging radiation; 4) Chemical modification of the stratum corneum by topically applied substances which can conjugate chemically or be absorbed onto the stratum corneum and filter the damaging rays. Many authors at present consider the use of alcoholic solutions of para-aminobenzoic acid (PABA) to be the most effective method of preventing reactions from exposure to sunlight. Pathak and Fitzpatrick showed that 5 % PABA in 70 % ethanol and 2,5 % Escalol 506 in 65 % ethanol is the most effective sunscreen against radiation of the sunburn spectrum. A dihydroxyacetone (DHA) and naphthaquinone (lawsone) sunscreen provides photoprotection for all

  7. Degradation of the performance of microchannel heat exchangers due to flow maldistribution

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Engelbrecht, Kurt; Christensen, Dennis

    2012-01-01

    The effect of flow maldistribution on the performance of microchannel parallel plate heat exchangers is investigated using an established single blow numerical model and cyclic steady-state regenerator experiments. It is found that as the variation of the individual channel thickness in a particu......The effect of flow maldistribution on the performance of microchannel parallel plate heat exchangers is investigated using an established single blow numerical model and cyclic steady-state regenerator experiments. It is found that as the variation of the individual channel thickness...

  8. Therapeutic plasma exchange and pregnancy: A case report and guidelines for performing plasma exchange in a pregnant patient.

    Science.gov (United States)

    Cox, Jesse L; Koepsell, Scott A; Shunkwiler, Sara M

    2017-06-01

    Therapeutic plasma exchange (TPE) has been demonstrated to be of significant clinical value in a number of diseases and conditions, with well-established guidelines and recommendations. However, technical support in providing this procedure for pregnant patients is largely absent from these recommendations, leaving therapeutic apheresis practitioners without guidance to safely and adequately treat appropriate conditions in this important patient population. Here, we describe our experience in treating a 35-year-old pregnant patient with relapsing-remitting multiple sclerosis with TPE. Additionally, we outline the principle considerations when developing her treatment plan, and we provide recommendations for apheresis practitioners when performing TPE in pregnant patients. J. Clin. Apheresis 32:191-195, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  9. Dehumidification performance investigation of run-around membrane energy exchanger system

    Directory of Open Access Journals (Sweden)

    Kassai Miklos

    2016-01-01

    Full Text Available Liquid-to-air membrane energy exchanger is a novel membrane base energy exchanger, which allows both heat and moisture transfer between air and a salt solution. It uses semi-permeable membrane to eliminate entrainment of liquid desiccant as aerosols in air stream and allow simultaneous heat and moisture transfer between salt solution flow and airflow. The heat and mass transfer performance of a single liquid-to-air membrane energy exchanger is significantly dependent on two dimensionless parameters. They are the number of heat transfer units (NTU and the ratio of heat capacity rates between solution flow and air flow (Cr*. The liquid-to-air membrane energy exchangers can also be applied in a run-around membrane energy exchanger system, which is mainly comprised of two liquid-to-air membrane energy exchangers and a closed loop of aqueous desiccant solution and used as a passive energy recovery system to recover the energy (both heat and moisture from the exhaust air to precondition the supply air in air conditioning systems. In this study the dehumidification capacity of a run-around membrane energy exchanger is investigated numerically at different exhaust air temperatures and Cr* values. Increasing the exhaust air temperature or the Cr* would enhance the dehumidification capacity of the a run-around membrane energy exchanger system under Cr*≤1, but the improvement is limited. The dehumidification capacity at low Cr* is much lower than that under the optimal Cr* value (Cr*=3.2 where the maximum latent effectiveness is obtained.

  10. Performance analysis of an organic Rankine cycle with internal heat exchanger having zeotropic working fluid

    Directory of Open Access Journals (Sweden)

    Thoranis Deethayat

    2015-09-01

    Full Text Available In this study, performance of a 50 kW organic Rankine cycle (ORC with internal heat exchanger (IHE having R245fa/R152a zeotropic refrigerant with various compositions was investigated. The IHE could reduce heat rate at the ORC evaporator and better cycle efficiency could be obtained. The zeotropic mixture could reduce the irreversibilities during the heat exchanges at the ORC evaporator and the ORC condenser due to its gliding temperature; thus the cycle working temperatures came closer to the temperatures of the heat source and the heat sink. In this paper, effects of evaporating temperature, mass fraction of R152a and effectiveness of internal heat exchanger on the ORC performances for the first law and the second law of thermodynamics were considered. The simulated results showed that reduction of R245fa composition could reduce the irreversibilities at the evaporator and the condenser. The suitable composition of R245fa was around 80% mass fraction and below this the irreversibilities were nearly steady. Higher evaporating temperature and higher internal heat exchanger effectiveness also increased the first law and second law efficiencies. A set of correlations to estimate the first and the second law efficiencies with the mass fraction of R245fa, the internal heat exchanger effectiveness and the evaporating temperature were also developed.

  11. Evaluating the performance of global emerging markets equity exchange-traded funds

    NARCIS (Netherlands)

    D.C. Blitz (David); J.J. Huij (Joop)

    2012-01-01

    textabstractWe examine the performance of passively managed exchange-traded funds (ETFs) that provide exposure to global emerging markets equities. We find that the tracking errors of these funds are substantially higher than previously reported levels for developed markets ETFs. ETFs that use

  12. Heat exchange performance of stainless steel and carbon foams modified with carbon nano fibers

    NARCIS (Netherlands)

    Tuzovskaya, I.; Pacheco Benito, Sergio; Chinthaginjala, J.K.; Reed, C.P.; Lefferts, Leonardus; van der Meer, Theodorus H.

    2012-01-01

    Carbon nanofibers (CNF), with fishbone and parallel wall structures, were grown by catalytic chemical vapor deposition on the surface of carbon foam and stainless steel foam, in order to improve their heat exchange performance. Enhancement in heat transfer efficiency between 30% and 75% was achieved

  13. Is Small Beautiful? Size Effects of Volatility Spillovers for Firm Performance and Exchange Rates in Tourism

    NARCIS (Netherlands)

    C-L. Chang (Chia-Lin); H-K. Hsu (Hui-Kuang); M.J. McAleer (Michael)

    2013-01-01

    textabstractThis paper examines the size effects of volatility spillovers for firm performance and exchange rates with asymmetry in the Taiwan tourism industry. The analysis is based on two conditional multivariate models, BEKK-AGARCH and VARMA-AGARCH, in the volatility specification. Daily data

  14. Is Small Beautiful? Size Effects of Volatility Spillovers for Firm Performance and Exchange Rates in Tourism

    NARCIS (Netherlands)

    C-L. Chang (Chia-Lin); H-K. Hsu (Hui-Kuang); M.J. McAleer (Michael)

    2012-01-01

    textabstractThis paper examines the size effects of volatility spillovers for firm performance and exchange rates with asymmetry in the Taiwan tourism industry. The analysis is based on two conditional multivariate models, BEKK-AGARCH and VARMA-AGARCH, in the volatility specification. Daily data

  15. Performance measurement of plate fin heat exchanger by exploration: ANN, ANFIS, GA, and SA

    Directory of Open Access Journals (Sweden)

    A.K. Gupta

    2017-01-01

    Full Text Available An experimental work is conducted on counter flow plate fin compact heat exchanger using offset strip fin under different mass flow rates. The training, testing, and validation set of data has been collected by conducting experiments. Next, artificial neural network merged with Genetic Algorithm (GA utilized to measure the performance of plate-fin compact heat exchanger. The main aim of present research is to measure the performance of plate-fin compact heat exchanger and to provide full explanations. An artificial neural network predicted simulated data, which verified with experimental data under 10–20% error. Then, the authors examined two well-known global search techniques, simulated annealing and the genetic algorithm. The proposed genetic algorithm and Simulated Annealing (SA results have been summarized. The parameters are impartially important for good results. With the emergence of a new data-driven modeling technique, Neuro-fuzzy based systems are established in academic and practical applications. The neuro-fuzzy interference system (ANFIS has also been examined to undertake the problem related to plate-fin heat exchanger performance measurement under various parameters. Moreover, Parallel with ANFIS model and Artificial Neural Network (ANN model has been created with emphasizing the accuracy of the different techniques. A wide range of statistical indicators used to assess the performance of the models. Based on the comparison, it was revealed that technical ANFIS improve the accuracy of estimates in the small pool and tropical ANN.

  16. Heat transfer performance test of PDHRS heat exchangers of PGSFR using STELLA-1 facility

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jonggan, E-mail: hong@kaeri.re.kr; Yeom, Sujin; Eoh, Jae-Hyuk; Lee, Tae-Ho; Jeong, Ji-Young

    2017-03-15

    Highlights: • Heat transfer performance test of heat exchangers of PGSFR PDHRS is conducted using STELLA-1 facility. • Steady-state test results of DHX and AHX show good agreement with theoretical results of design codes. • Design codes for DHX and AHX are validated by STELLA-1 experimental results. • Heat transport capability of DHX and AHX is turned out to be satisfactory for reliable plant operation. - Abstract: The STELLA-1 facility was designed and constructed to carry out separate effect tests of the decay heat exchanger (DHX) and natural draft sodium-to-air heat exchanger (AHX), which are key components of the safety-grade decay heat removal system in PGSFR. The DHX is a sodium-to-sodium heat exchanger with a straight tube arrangement, and the AHX is a sodium-to-air heat exchanger with a helically coiled tube arrangement. The model heat exchangers in STELLA-1 have been designed to meet their own similitude conditions from the prototype ones, of which scale ratios were set to be unity in height (or length) and 1/2.5 in heat transfer rate. Consequently, the overall heat transfer coefficients and log-mean temperature differences of the prototypes have been preserved as well. The steady-state test results for each model heat exchanger obtained from STELLA-1 showed good agreement with the theoretical results of the computer design codes for thermal-sizing and a performance analysis of the DHX and AHX. In the DHX result comparison, the discrepancies in the heat transfer rate ranged from −4.4% to 2.0%, and in the AHX result comparison, they ranged from −11.1% to 12.6%. Therefore, the first step in thermal design codes validation for sodium heat exchangers, e.g., DHX and AHX, has been successfully completed with the experimental database obtained from STELLA-1. In addition, the heat transfer performance of the DHX and AHX was found to be satisfactory enough to secure a reliable decay heat removal performance.

  17. Effect of Liquid/Vapour Maldistribution on the Performance of Plate Heat Exchanger Evaporators

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Kærn, Martin Ryhl; Ommen, Torben Schmidt

    2015-01-01

    Plate heat exchangers are often applied as evaporators in industrial refrigeration and heat pump systems. In the design and modelling of such heat exchangers the flow and liquid/vapour distribution is often assumed to be ideal. However, maldistribution may occur and will cause each channel...... to behave differently due to the variation of the mass flux and vapour quality. To evaluate the effect of maldistribution on the performance of plate heat exchangers, a numerical model is developed in which the mass, momentum and energy balances are applied individually to each channel, including suitable...... correlations for heat transfer and pressure drop. The flow distribution on both the refrigerant and secondary side is determined based on equal pressure drop while the liquid/vapour distribution is imposed to the model. Results show that maldistribution may cause up to a 25 % reduction of the overall heat...

  18. Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

    Energy Technology Data Exchange (ETDEWEB)

    Mittereder, Nick [IBACOS, Inc., Pittsburgh, PA (United States); Poerschke, Andrew [IBACOS, Inc., Pittsburgh, PA (United States)

    2013-11-01

    This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season.

  19. Performance Assessment of 239 Series Sub-cooling Heat Exchangers for the Large Hadron Collider

    CERN Document Server

    Riddone, G; Roussel, P; Moracchioli, R; Tavian, L

    2006-01-01

    Helium sub-cooling heat exchangers of the counter-flow type are used to minimize the vapor fraction produced in the final expansion of the 1.9 K distributed cooling loops used for cooling the superconducting magnets of the Large Hadron Collider (LHC). These components are of compact design, featuring low-pressure drop and handling very low pressure vapor at low temperature. Following a qualification phase of prototypes, a contract has been placed in European industry for the supply of 239 heat exchanger units. Different levels of extracted heat load require three different variants of heat exchangers. This paper will describe the manufacturing phase with emphasis on the main difficulties encountered to keep the production quality after a brief recall of the prototype phase. Finally, the acceptance tests performed at room temperature and at the nominal cryogenic condition at the factory and at CEA-Grenoble will be presented.

  20. Performance of adsorbent-embedded heat exchangers using binder-coating method

    KAUST Repository

    Li, Ang

    2016-01-01

    The performance of adsorption (AD) chillers or desalination cycles is dictated by the rates of heat and mass transfer of adsorbate in adsorbent-packed beds. Conventional granular-adsorbent, packed in fin-tube heat exchangers, suffered from poor heat transfer in heating (desorption) or cooling (adsorption) processes of the batch-operated cycles, with undesirable performance parameters such as higher footprint of plants, low coefficient of performance (COP) of AD cycles and higher capital cost of the machines. The motivation of present work is to mitigate the heat and mass "bottlenecks" of fin-tube heat exchangers by using a powdered-adsorbent cum binder coated onto the fin surfaces of exchangers. Suitable adsorbent-binder pairs have been identified for the silica gel adsorbent with pore surface areas up to 680 m2/g and pore diameters less than 6 nm. The parent silica gel remains largely unaffected despite being pulverized into fine particles of 100 μm, and yet maintaining its water uptake characteristics. The paper presents an experimental study on the selection and testing processes to achieve high efficacy of adsorbent-binder coated exchangers. The test results indicate 3.4-4.6 folds improvement in heat transfer rates over the conventional granular-packed method, resulting a faster rate of water uptake by 1.5-2 times on the suitable silica gel type. © 2015 Elsevier Ltd. All rights reserved.

  1. Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

    Energy Technology Data Exchange (ETDEWEB)

    Mittereder, N.; Poerschke, A.

    2013-11-01

    This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season. Upon completion of the monitoring phase, measurements revealed that the initial TRNSYS simulated horizontal sub-slab ground loop heat exchanger fluid temperatures and heat transfer rates differed from the measured values. To determine the cause of this discrepancy, an updated model was developed utilizing a new TRNSYS subroutine for simulating sub-slab heat exchangers. Measurements of fluid temperature, soil temperature, and heat transfer were used to validate the updated model.

  2. Air-side performance evaluation of three types of heat exchangers in dry, wet and periodic frosting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ping [Zhejiang Vocational College of Commerce, Hangzhou, Binwen Road 470 (China); Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 West Green Street, Urbana, IL 61801 (United States); Hrnjak, P.S. [Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 West Green Street, Urbana, IL 61801 (United States)

    2009-08-15

    The performances of three types of heat exchangers that use the louver fin geometry: (1) parallel flow parallel fin with extruded flat tubes heat exchanger (PF{sup 2}), (2) parallel flow serpentine fin with extruded flat tubes heat exchanger (PFSF) and (3) round tube wave plate fin heat exchanger (RTPF) have been experimentally studied under dry, wet and frost conditions and results are presented. The parameters quantified include air-side pressure drop, water retention on the surface of the heat exchanger, capacity and overall heat transfer coefficient for air face velocity 0.9, 2 and 3 m/s, air humidity 70% and 80% and different orientations. The performances of three types of heat exchanger are compared and the results obtained are presented. The condensate drainage behavior of the air-side surface of these three heat exchanger types was studied using both the dip testing method and wind tunnel experiment. (author)

  3. Photosynthesis and photoprotective systems of plants in response to ...

    African Journals Online (AJOL)

    Yomi

    2010-12-27

    Dec 27, 2010 ... assimilation, as well as some aspects needed to be further studied are also discussed. Key words: Aluminum toxicity, photosynthesis, photochemistry, photoprotective system. INTRODUCTION. Aluminum (Al) is the most abundant metal and the third most abundant element in the earth's crust after oxygen.

  4. Natural compounds for solar photoprotection: a patent review.

    Science.gov (United States)

    Serafini, Mairim R; Guimarães, Adriana G; Quintans, Jullyana S S; Araújo, Adriano A S; Nunes, Paula S; Quintans-Júnior, Lucindo J

    2015-04-01

    Ultraviolet irradiation has deleterious effects on human skin, including tanning, sunburn, cancer and connective tissue degradation (photoaging). Botanical antioxidants have been shown to be associated with reduced incidence of photocarcinogenesis and photoaging through their photoprotective profile. Here, the authors summarized therapeutic patent applications concerning the employment of medicinal plants on the technological development of a formulation with photoprotective or photoaging application. So, the patent search was conducted in the databases WIPO, Espacenet, USPTO and Derwent, using the keywords - photoaging, photoprotection and the IPC A61K 8/97 (cosmetics or similar cleaning supplies obtained from vegetable origin, for example, plant extracts) and A61K 36/00 (medicinal preparations of undetermined constitution containing material from algae, lichens, fungi or plants, or derivatives thereof, for example, traditional herbal medicines). We found 180 patents, out of which 25 were evaluated using inclusion criteria as application of natural products with photoprotective or photoaging application. We found that some patents related to the cosmetic compositions for improving skin wrinkle and either preventing or reducing the signs of photoaging and sunburn. The cosmetic compositions are manufactured in the form of a lotion, gel, soluble liquid, cream, essence, oil-in-water-type or water-in-oil-type formulation, containing the vegetal extracts as an active ingredient.

  5. Superior photoprotective motifs and mechanisms in eumelanins uncovered

    NARCIS (Netherlands)

    Corani, Alice; Huijser, Jannetje Maria; Gustavsson, Thomas; Markovitsi, Dimitra; Malmqvist, Per-Ake; Pezzella, Alessandro; D'Ischia, Marco; Sundström, Villy

    2014-01-01

    Human pigmentation is a complex phenomenon commonly believed to serve a photoprotective function through the generation and strategic localization of black insoluble eumelanin biopolymers in sun exposed areas of the body. Despite compelling biomedical relevance to skin cancer and melanoma, eumelanin

  6. A review on improving thermal-hydraulic performance of fin-and-tube heat exchangers

    Science.gov (United States)

    Nickolas, N.; Moorthy, P.; Oumer, A. N.; Ishak, M.

    2017-10-01

    Fin-and-tube heat exchangers are one of the most common type of heat exchangers that are normally used in sectors that require small size and light weight but high heat transfer capabilities. Compact fin-and-tube heat exchangers experiences high convective thermal resistance at the air-side due to the thermo-physical properties of air. Thus, the purpose of this paper is to provide an overview of research works that are relevant to improving thermalhydraulic performance at the air-side of fin-and-tube heat exchangers. This paper covers a variety of parameters such as tube parameters like tube arrangement, tube shapes and tube inclination angles; extended surfaces such as different shapes of fins and different parameters of vortex generators like attack angles, shapes and locations. Overall, for most modifications there was increment in heat transfer but accompanied with a pressure drop penalty. However, this varies for different combinations of parameters thus this review is to help understand how every mentioned parameters influences the thermal-hydraulic performance.

  7. Effects of seasonality and a daily photo-protection upon some facial signs of Chinese women.

    Science.gov (United States)

    Flament, F; Qiu, H

    2017-06-01

    These were two-fold: (i) to record through standardized pictures, the possible changes in 31 facial signs induced, in a 6-month period, by the periodical shift from winter to summer in a group of 43 Chinese women and (ii) to appraise the preventive effects of a strong photo-protective product, daily applied to the faces of an additional group (N = 40) of women of same age-range and presenting same severities of facial signs in winter. Facial signs (structural and pigmentation-related) were scored in blind by a panel of 12 experts from photographs taken under standard conditions. Scorings were performed under specific scales as established by a previously published referential Skin Aging Atlas, Volume 2, Asian Type. A significant seasonal impact was found for more than 60% of facial signs, that is presenting a higher severity in summer in the unprotected group. Some changes are of a low or subtle extent, whereas some others show significant amplitudes. The latter comprise eight signs, among the 31, that became, far above scoring threshold, indeed affected during this 6-month period. The observed changes in six of these eight signs, in majority related to pigmentation, appeared efficiently alleviated in the photo-protected group. The shift from winter to summer exposure is confirmed in altering some facial pigmented signs among Chinese women. Such changes appear much alleviated by a daily strong photo-protective regimen. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  8. Ion-pair, anion-exchange and ligand-exchange high-performance liquid chromatography of tenuazonic acid and 3-acetyl 5-substituted pyrrolidine-2,4-diones.

    Science.gov (United States)

    Lebrun, M H; Gaudemer, F; Boutar, M; Nicolas, L; Gaudemer, A

    1989-03-03

    The ion-pair, ligand-exchange and anion-exchange chromatography of the fungal metabolic tenuazonic acid (TA) and its related 3-acetyl 5-substituted pyrrolidine-2,4-diones were studied. Ion-pair chromatography was performed on a C18 column with a mobile phase composed of cetrimide, phosphate buffer in water-methanol and a metal complexant (ethylenediamine) to improve the peak sharpness. Addition of the same metal complexant to the mobile phase of the anion-exchange chromatographic system also improved its efficiency. TA and its 5-substituted analogues derived from valine and leucine were separated with the ion-pair and anion-exchange chromatographic systems. With ligand-exchange chromatography, TA could only be separated from its valine analogue. These chromatographic systems were used for the detection of TA in the culture filtrates of the fungus Pyricularia oryzae and in infected rice leaves. Deproteinated culture filtrates could be rapidly analysed for their TA content by anion-exchange chromatography. However, this system was not suitable for the detection of TA in the infected rice leaf as interfering compounds were coeluted with TA. Ion-pair and ligand-exchange chromatographic systems allowed the efficient quantification of TA in infected leaves.

  9. Improved gas exchange performance of the intravascular oxygenator by active blood mixing.

    Science.gov (United States)

    Tao, W; Schroeder, T; Bidani, A; Cardenas, V J; Nguyen, P D; Bradford, D W; Traber, D L; Zwischenberger, J B

    1994-01-01

    The intravascular oxygenator and carbon dioxide removal device (IVOX; CardioPulmonics, Salt Lake City, UT) has been shown to perform 30% of the gas exchange in animals and patients with acute respiratory failure. Among the factors that limit gas exchange is the mass transfer resistance in the blood phase. To determine if a reduction in mass transfer resistance by mixing venous blood can enhance the O2 transfer and CO2 removal by IVOX, a right atrium-pulmonary artery venovenous bypass circuit was used in sheep to model the adult vena cava. A size 9 IVOX (894 fibers with 0.41 m2 surface area, n = 5) was incorporated in the bypass circuit and the blood flow controlled by a roller pump ranging from 1 to 4 l/min. An intra-aortic balloon was placed near the shaft of the IVOX and pulsated at the rate adjusted to best improve CO2 removal (100-120 bpm). O2 transfer and CO2 removal were measured with balloon pulsation on and off at different flow rates. Results showed that blood mixing by pulsation of the balloon caused a 25-49% increase in O2 transfer by IVOX, and this increase remained relatively constant throughout the full flow range. CO2 removal was also increased by up to 35%, but at flows between 3.5 and 4 l/min, the effect of mixing was diminished. It is concluded that reduction in the mass transfer resistance by blood mixing improves gas exchange. Because O2 is more diffusion limited, it is more dependent upon mixing of blood for gas exchange than CO2. More design improvements to incorporate active mixing may further enhance the gas exchange performance of IVOX.

  10. Numerical investigation of conjugate heat transfer and flow performance of a fin and tube heat exchanger with vortex generators

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim

    2017-01-01

    Vortex generator is considered as an effective device for augmentation of the thermal-hydraulic performance of a heat exchanger. The aim of present study is to examine the influence of vortex generators on a double fin and tube heat exchanger performance. Vortex generator of rectangular winglet...... loss characteristics are determined and analyzed for an in-line configuration of a fin and tube heat exchanger. In order to evaluate the enhancement in the performance on an equitable basis, the heat exchanger with plain fin surface is considered as a reference design. Results show that the angle...... of attack of a vortex generator has a significant impact on the volume goodness factor, and enhance the thermal performance of a fin and tube heat exchanger in comparison to the design with plain fin. The vortex generator at an angle of attack ??10 is found to perform superior over the Reynolds number range...

  11. Rapid detection of malto-oligosaccharide-forming bacterial amylases by high performance anion-exchange chromatography

    DEFF Research Database (Denmark)

    Duedahl-Olesen, Lene; Larsen, K. L.; Zimmermann, W.

    2000-01-01

    High performance anion-exchange chromatography with pulsed amperometric detection was applied for the rapid analysis of malto-oligosaccharides formed by extracellular enzyme preparations from 49 starch-degrading bacterial strains isolated from soil and compost samples. Malto-oligosaccharide-formi......High performance anion-exchange chromatography with pulsed amperometric detection was applied for the rapid analysis of malto-oligosaccharides formed by extracellular enzyme preparations from 49 starch-degrading bacterial strains isolated from soil and compost samples. Malto......-oligosaccharide-forming amylases, indicated by a predominant formation of maltohexaose from starch, were produced by enzyme preparations from four of the isolates growing at pH 7.0 and 10....

  12. Structural and preliminary thermal performance testing of a pressure activated contact heat exchanger

    Science.gov (United States)

    Lee, C. Y.; Christian, E. L.; Wohlwend, J. W.; Parish, R. C.

    1987-01-01

    A contact heat exchanger concept is being developed for use onboard Space Station as an interface device between external thermal bus and pressurized modules. The concept relies on mechanical contact activated by the fluid pressure inside thin-walled tubes. Structural testings were carried out to confirm the technology feasibility of using such thin-walled tubes. The test results also verified the linear elastic stress analysis which was used to predict the tube mechanical behaviors. A preliminary thermal testing was also performed with liquid Freon-11 flowing inside tubes and heat being supplied by electrical heating from the bottom of the contact heat exchanger baseplate. The test results showed excellent agreement of test data with analytical prediction for all thermal resistances except for the two-phase flow characteristics. Testing with two-phase flow inside tubes will, however, be performed on the NASA-JSC test bed.

  13. Performance study of a fin and tube heat exchanger with different fin geometry

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

    2016-01-01

    This study analyses the effect of different fin geometries on the heat transfer and pressure loss characteristics of a fin and tube heat exchanger. A numerical investigation is carried out on liquid–gas type double-finned tube heat exchanger under cross-flow condition. Three different cross......-sections namely: a) Rectangular, b) Trapezoidal, c) Triangular are adopted to define the fin geometry. The CFD simulations are performed to incorporate coupled steady state conjugate heat transfer with the turbulent flow phenomenon for the Reynolds number in the range of 5000-13000. Dimensionless heat transfer...... models show that triangular fin geometry can provide higher heat transfer performance in comparison to the fins with rectangular and trapezoidal geometry with lower pressure loss and a bonus of 7.27% reduction in weight under similar operating conditions....

  14. Assessment of extracts of Helichrysum arenarium, Crataegus monogyna, Sambucus nigra in photoprotective UVA and UVB; photostability in cosmetic emulsions.

    Science.gov (United States)

    Jarzycka, Anna; Lewińska, Agnieszka; Gancarz, Roman; Wilk, Kazimiera A

    2013-11-05

    The aim of our study was to investigate the photoprotective activity and photostability efficacy of sunscreen formulations containing Helichrysum arenarium, Sambucus nigra, Crataegus monogyna extracts and their combination. UV transmission of the emulsion films was performed by using diffuse transmittance measurements coupling to an integrating sphere. In vitro photoprotection and photostability efficacy were evaluated according to the following parameters: sun protection factor (SPF), UVA protection factor (PF-UVA), UVA/UVB ratio and critical wavelength (λc) before and after UV irradiation. The results obtained show that the formulations containing polyphenols fulfill the official requirements for sunscreen products due to their broad spectrum of UV protection combined with their high photostability and remarkable antioxidant properties. Therefore H. arenarium, S. nigra, C. monogyna extracts represent useful additives for cosmetic formulation. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Performing multiobjective optimization on perforated plate matrix heat exchanger surfaces using genetic algorithm

    Directory of Open Access Journals (Sweden)

    John Anish K.

    2017-01-01

    Full Text Available Matrix Heat Exchanger is having wide spread applications in cryogenics and aerospace, where high effectiveness and compactness is essential. This can be achieved by providing high thermal conductive plates and low thermal conductive spacers alternately. These perforated plate matrix heat exchangers have near to 100% efficiency due to low longitudinal heat transfer. The heat transfer and flow friction characteristics of a perforated plate matrix heat exchanger can be represented using Colburn factor and friction factor. In this paper, dimensionless parameters like Reynolds number (Re, porosity (p, perforation perimeter factor (P f, plate thickness to pore diameter ratio (l/d and spacer thickness to plate thickness ratio (s/l have been optimized for maximum Colburn factor and minimum friction factor using genetic algorithm. Two algorithms, one for single objective and the other for multi-objective problems, which are believed to be more efficient, are described. The algorithms coded with MATLAB, is used to perform multi-objective optimization on perforated plate matrix heat exchanger surfaces. The results show promising results.

  16. Air-side performance of a micro-channel heat exchanger in wet surface conditions

    Directory of Open Access Journals (Sweden)

    Srisomba Raviwat

    2017-01-01

    Full Text Available The effects of operating conditions on the air-side heat transfer, and pressure drop of a micro-channel heat exchanger under wet surface conditions were studied experimentally. The test section was an aluminum micro-channel heat exchanger, consisting of a multi-louvered fin and multi-port mini-channels. Experiments were conducted to study the effects of inlet relative humidity, air frontal velocity, air inlet temperature, and refrigerant temperature on air-side performance. The experimental data were analyzed using the mean enthalpy difference method. The test run was performed at relative air humidities ranging between 45% and 80%; air inlet temperature ranges of 27, 30, and 33°C; refrigerant-saturated temperatures ranging from 18 to 22°C; and Reynolds numbers between 128 and 166. The results show that the inlet relative humidity, air inlet temperature, and the refrigerant temperature had significant effects on heat transfer performance and air-side pressure drop. The heat transfer coefficient and pressure drop for the micro-channel heat exchanger under wet surface conditions are proposed in terms of the Colburn j factor and Fanning f factor.

  17. Refrigerant Performance Evaluation Including Effects of Transport Properties and Optimized Heat Exchangers.

    Science.gov (United States)

    Brignoli, Riccardo; Brown, J Steven; Skye, H; Domanski, Piotr A

    2017-08-01

    Preliminary refrigerant screenings typically rely on using cycle simulation models involving thermodynamic properties alone. This approach has two shortcomings. First, it neglects transport properties, whose influence on system performance is particularly strong through their impact on the performance of the heat exchangers. Second, the refrigerant temperatures in the evaporator and condenser are specified as input, while real-life equipment operates at imposed heat sink and heat source temperatures; the temperatures in the evaporator and condensers are established based on overall heat transfer resistances of these heat exchangers and the balance of the system. The paper discusses a simulation methodology and model that addresses the above shortcomings. This model simulates the thermodynamic cycle operating at specified heat sink and heat source temperature profiles, and includes the ability to account for the effects of thermophysical properties and refrigerant mass flux on refrigerant heat transfer and pressure drop in the air-to-refrigerant evaporator and condenser. Additionally, the model can optimize the refrigerant mass flux in the heat exchangers to maximize the Coefficient of Performance. The new model is validated with experimental data and its predictions are contrasted to those of a model based on thermodynamic properties alone.

  18. Can Leader–Member Exchange Contribute to Safety Performance in An Italian Warehouse?

    Science.gov (United States)

    Mariani, Marco G.; Curcuruto, Matteo; Matic, Mirna; Sciacovelli, Paolo; Toderi, Stefano

    2017-01-01

    Introduction: The research considers safety climate in a warehouse and wants to analyze the Leader–Member Exchange (LMX) role in respect to safety performance. Griffin and Neal’s safety model was adopted and Leader-Member Exchange was inserted as moderator in the relationships between safety climate and proximal antecedents (motivation and knowledge) of safety performance constructs (compliance and participation). Materials and Methods: Survey data were collected from a sample of 133 full-time employees in an Italian warehouse. The statistical framework of Hayes (2013) was adopted for moderated mediation analysis. Results: Proximal antecedents partially mediated the relationship between Safety climate and safety participation, but not safety compliance. Moreover, the results from the moderation analysis showed that the Leader–Member Exchange moderated the influence of safety climate on proximal antecedents and the mediation exist only at the higher level of LMX. Conclusion: The study shows that the different aspects of leadership processes interact in explaining individual proficiency in safety practices. Practical Implications: Organizations as warehouses should improve the quality of the relationship between a leader and a subordinate based upon the dimensions of respect, trust, and obligation for high level of safety performance. PMID:28553244

  19. Can Leader–Member Exchange Contribute to Safety Performance in An Italian Warehouse?

    Directory of Open Access Journals (Sweden)

    Marco G. Mariani

    2017-05-01

    Full Text Available Introduction: The research considers safety climate in a warehouse and wants to analyze the Leader–Member Exchange (LMX role in respect to safety performance. Griffin and Neal’s safety model was adopted and Leader-Member Exchange was inserted as moderator in the relationships between safety climate and proximal antecedents (motivation and knowledge of safety performance constructs (compliance and participation.Materials and Methods: Survey data were collected from a sample of 133 full-time employees in an Italian warehouse. The statistical framework of Hayes (2013 was adopted for moderated mediation analysis.Results: Proximal antecedents partially mediated the relationship between Safety climate and safety participation, but not safety compliance. Moreover, the results from the moderation analysis showed that the Leader–Member Exchange moderated the influence of safety climate on proximal antecedents and the mediation exist only at the higher level of LMX.Conclusion: The study shows that the different aspects of leadership processes interact in explaining individual proficiency in safety practices.Practical Implications: Organizations as warehouses should improve the quality of the relationship between a leader and a subordinate based upon the dimensions of respect, trust, and obligation for high level of safety performance.

  20. Can Leader-Member Exchange Contribute to Safety Performance in An Italian Warehouse?

    Science.gov (United States)

    Mariani, Marco G; Curcuruto, Matteo; Matic, Mirna; Sciacovelli, Paolo; Toderi, Stefano

    2017-01-01

    Introduction: The research considers safety climate in a warehouse and wants to analyze the Leader-Member Exchange (LMX) role in respect to safety performance. Griffin and Neal's safety model was adopted and Leader-Member Exchange was inserted as moderator in the relationships between safety climate and proximal antecedents (motivation and knowledge) of safety performance constructs (compliance and participation). Materials and Methods: Survey data were collected from a sample of 133 full-time employees in an Italian warehouse. The statistical framework of Hayes (2013) was adopted for moderated mediation analysis. Results: Proximal antecedents partially mediated the relationship between Safety climate and safety participation, but not safety compliance. Moreover, the results from the moderation analysis showed that the Leader-Member Exchange moderated the influence of safety climate on proximal antecedents and the mediation exist only at the higher level of LMX. Conclusion: The study shows that the different aspects of leadership processes interact in explaining individual proficiency in safety practices. Practical Implications: Organizations as warehouses should improve the quality of the relationship between a leader and a subordinate based upon the dimensions of respect, trust, and obligation for high level of safety performance.

  1. In vitro and in vivo evaluation of efficacy and safety of photoprotective formulations containing antioxidant extracts

    Directory of Open Access Journals (Sweden)

    Maria Cristina P.P. Reis Mansur

    Full Text Available ABSTRACT Chronic exposure to solar radiation could contribute to premature skin aging and skin cancer. Skin presents its own antioxidant defense, however when defenses are out of balance, reactive oxygen species could damage biological structures. In the present work, an oil-in-water photoprotective emulsion was developed and Bauhinia microstachya var. massambabensis Vaz, Fabaceae, extracts at 1% (obtained by extraction with different solvents were added to this emulsion. In vitro and in vivo efficacy and safety of the formulations were evaluated. Spectrophotometric methods and in vivo Colipa test were performed to evaluated efficacy of the formulations, through sun protection factor (SPF determination and UVA protection factor assessment. To the in vitro safety assessment HET-CAM, CAM-TBS and Red Blood Cell tests were performed. Results showed that both extracts contributed to a higher in vivo photoprotection (SPF 18 when compared to the formulation without extract (SPF 13, this result could be attributed to the antioxidant activity of the plant extracts that act by capturing reactive oxygen species. Concerning safety, all formulations were considered non-irritant according to in vitro tests. Formulations containing extracts could be considered efficient and safe for cosmetic use since they presented higher sun protection factor and passed the toxicity tests.

  2. Thermal performance analysis for heat exchangers having a variable overall heat transfer coefficient

    Science.gov (United States)

    Conklin, J. C.; Granryd, E.

    The classic, conventional analysis for the thermal performance of heat exchangers is based on three assumptions: constant fluid flow rate, constant specific heat fluids, and constant overall heat transfer coefficient. Our analysis describes a general approach for analyzing the thermal performance of heat exchangers in which the overall heat transfer coefficient varies as a function of enthalpy, with the other two basic assumptions of constant mass flow rates and constant specific heats unchanged. Many heat exchangers have an overall heat transfer coefficient that is not constant. The conventional heat exchanger thermal performance analysis is correct as long as a true, area-weighted mean value is used. In many applications, however, fluids undergo a change in phase, and the heat transfer coefficient is a function of the local quality or enthalpy; hence, the true, area-weighted, mean heat transfer coefficient will be a function of the heat flux distribution. Examples are presented that illustrate the variation in overall heat transfer coefficient for an evaporation process. We present a general method for computing a true, area-weighted mean overall heat transfer coefficient that permits use of a local overall heat transfer coefficient that is an arbitrary function of enthalpy. This method allows a simple yet accurate analysis of the effects of a variable overall heat transfer coefficient to be made without the use of a large mainframe computer. We then investigate: (1) linear variation of local overall heat transfer coefficient with respect to enthalpy; and (2) two heat transfer correlations applicable to flow-boiling inside a tube.

  3. Photosynthetic limitation and mechanisms of photoprotection under drought and recovery of Calotropis procera, an evergreen C3 from arid regions.

    Science.gov (United States)

    Rivas, Rebeca; Frosi, Gabriella; Ramos, Diego G; Pereira, Silvia; Benko-Iseppon, Ana M; Santos, Mauro G

    2017-09-01

    Calotropis procera is a C3 plant native from arid environmental zones. It is an evergreen, shrubby, non-woody plant with intense photosynthetic metabolism during the dry season. We measured photosynthetic parameters and leaf biochemical traits, such as gas exchange, photochemical parameters, A/Ci analysis, organic solutes, and antioxidant enzymes under controlled conditions in potted plants during drought stress, and following recovery conditions to obtain a better insight in the drought stress responses of C. procera. Indeed, different processes contribute to the drought stress resilience of C. procera and to the fast recovery after rehydration. The parameters analyzed showed that C. procera has a high efficiency for energy dissipation. The photosynthetic machinery is protected by a robust antioxidant system and photoprotective mechanisms such as alternative pathways for electrons (photorespiration and day respiration). Under severe drought stress, increased stomatal limitation and decreased biochemical limitation permitted C. procera to maintain maximum rate of Rubisco carboxylation (Vc,max) and photosynthetic rate (Amax). On the other hand, limitation of stomatal or mesophyll CO2 diffusion did not impair fast recovery, maintaining Vc,max, chloroplast CO2 concentration (Cc) and mesophyll conductance (gm) unchanged while electron flow used for RuBP carboxylation (Jc) and Amax increased. The ability to tolerate drought stress and the fast recovery of this evergreen C3 species was also due to leaf anti-oxidative stress enzyme activity, and photosynthetic pigments. Thus, these different drought tolerance mechanisms allowed high performance of photosynthetic metabolism by drought stressed plants during the re-watering period. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  4. A gas-exchange system for assessing plant performance in response to environmental stress

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, G.E. Jr; Tingey, D.T.

    1979-10-01

    Anthropogenic stresses are increasingly common as environmental factors affecting the performance of plants in both natural and agro-ecosystems. There is a need to determine how these stresses may influence vital physiological processes in plants. This report documents the design, construction and performance of a whole-plant, gas-exchange system that can accurately monitor gas flux (e.g., carbon dioxide, water vapor, pollutants) between plants and the atmospheric environment. From these data, rates of key physiological processes--photosynthesis, transpiration, gaseous uptake and emission--can be assessed. Example studies are reported on the uptake of sulfur dioxide by plants and emissions of monoterpenes from plants.

  5. Explaining the justice-performance relationship: trust as exchange deepener or trust as uncertainty reducer?

    Science.gov (United States)

    Colquitt, Jason A; Lepine, Jeffery A; Piccolo, Ronald F; Zapata, Cindy P; Rich, Bruce L

    2012-01-01

    Past research has revealed significant relationships between organizational justice dimensions and job performance, and trust is thought to be one mediator of those relationships. However, trust has been positioned in justice theorizing in 2 different ways, either as an indicator of the depth of an exchange relationship or as a variable that reflects levels of work-related uncertainty. Moreover, trust scholars distinguish between multiple forms of trust, including affect- and cognition-based trust, and it remains unclear which form is most relevant to justice effects. To explore these issues, we built and tested a more comprehensive model of trust mediation in which procedural, interpersonal, and distributive justice predicted affect- and cognition-based trust, with those trust forms predicting both exchange- and uncertainty-based mechanisms. The results of a field study in a hospital system revealed that the trust variables did indeed mediate the relationships between the organizational justice dimensions and job performance, with affect-based trust driving exchange-based mediation and cognition-based trust driving uncertainty-based mediation.

  6. An experimental investigation on air-side performances of finned tube heat exchangers for indirect air-cooling tower

    Directory of Open Access Journals (Sweden)

    Du Xueping

    2014-01-01

    Full Text Available A tremendous quantity of water can be saved if the air cooling system is used, comparing with the ordinary water-cooling technology. In this study, two kinds of finned tube heat exchangers in an indirect air-cooling tower are experimentally studied, which are a plain finned oval-tube heat exchanger and a wavy-finned flat-tube heat exchanger in a cross flow of air. Four different air inlet angles (90°, 60 °, 45°, and 30° are tested separately to obtain the heat transfer and resistance performance. Then the air-side experimental correlations of the Nusselt number and friction factor are acquired. The comprehensive heat transfer performances for two finned tube heat exchangers under four air inlet angles are compared. For the plain finned oval-tube heat exchanger, the vertical angle (90° has the worst performance while 45° and 30° has the best performance at small ReDc and at large ReDc, respectively. For the wavy-finned flat-tube heat exchanger, the worst performance occurred at 60°, while the best performance occurred at 45° and 90° at small ReDc and at large ReDc, respectively. From the comparative results, it can be found that the air inlet angle has completely different effects on the comprehensive heat transfer performance for the heat exchangers with different structures.

  7. Partial characterization, UV-induction and photoprotective function of sunscreen pigment, scytonemin from Rivularia sp. HKAR-4.

    Science.gov (United States)

    Rastogi, Rajesh P; Sinha, Rajeshwar P; Incharoensakdi, Aran

    2013-11-01

    Scytonemin, located in the extracellular polysaccharide sheath of some cyanobacterial species is considered an efficient natural photoprotectant against lethal doses of ultraviolet (UV) radiations. In the present study, scytonemin from the cyanobacterium Rivularia sp. HKAR-4 was partially characterized and investigated for its induction by UV radiation as well as its role in photoprotection. High-performance liquid chromatography (HPLC) with photodiode-array detection studies revealed the presence of an UV-absorbing compound with absorption maximum at 386 nm. Based on its absorption spectrum and ion trap liquid chromatography/mass spectrometry (LC/MS) analysis, the compound was confirmed as scytonemin. In comparison to photosynthetically active radiation, a significant induction in the synthesis of scytonemin was found under UV-stress. Scytonemin also exhibited efficient photoprotective ability by detoxifying the in vivo reactive oxygen species (ROS) generated by UV radiation and by reducing the formation of thymine dimers. To the best of our knowledge this is the first report on the UV-screening effects of scytonemin on in vivo ROS generation and thymine dimer formation in any cyanobacterial strain. Based on these findings, we conclude that scytonemin may play a vital role in the survival and sustainability of cyanobacterial life in adverse environmental conditions such as under high solar irradiances. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Implications of fin profiles on overall performance and weight reduction of a fin and tube heat exchanger

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Simonsen, Anders Schou

    2017-01-01

    Fin and tube heat exchangers are being used in several industrial applications by means of novel design and optimized performance. Improvements in geometric design may deliver energy efficient and cost-effective heat exchanger performance with reduced weight. In this paper, a systematic study......,000 using computational fluid dynamics. The numerical results obtained for the reference fin profile are verified with the experimental correlations. Dimensionless parameters such as Nusselt number, Euler number, and efficiency index are calculated to predict the overall performance of the heat exchanger...

  9. Probing nucleobase photoprotection with soft x-rays

    Directory of Open Access Journals (Sweden)

    Osipov T.

    2013-03-01

    Full Text Available Nucleobases absorb strongly in the ultraviolet region, leading to molecular excitation into reactive states. The molecules avoid the photoreactions by funnelling the electronic energy into less reactive states on an ultrafast timescale via non-Born-Oppenheimer dynamics. Current theory on the nucleobase thymine discusses two conflicting pathways for the photoprotective dynamics. We present our first results of our free electron laser based UV-pump soft x-ray-probe study of the photoprotection mechanism of thymine. We use the high spatial sensitivity of the Auger electrons emitted after the soft x-ray pulse induced core ionization. Our transient spetra show two timescales on the order of 200 fs and 5 ps, in agreement with previous (all UV ultrafast experiments. The timescales appear at different Auger kinetic energies which will help us to decipher the molecular dynamics.

  10. Effects of solar radiation on hair and photoprotection.

    Science.gov (United States)

    Dario, Michelli F; Baby, André R; Velasco, Maria Valéria R

    2015-12-01

    In this paper the negative effects of solar radiation (ultraviolet, visible and infrared wavelengths) on hair properties like color, mechanical properties, luster, protein content, surface roughness, among others, will be discussed. Despite knowing that radiation damages hair, there are no consensus about the particular effect of each segment of solar radiation on the hair shaft. The hair photoprotection products are primarily targeted to dyed hair, specially auburn pigments, and gray shades. They are usually based on silicones, antioxidants and quaternary chemical UV filters that have more affinity for negatively charged hair surface and present higher efficacy. Unfortunately, there are no regulated parameters, like for skin photoprotection, for efficacy evaluation of hair care products, which makes impossible to compare the results published in the literature. Thus, it is important that researchers make an effort to apply experimental conditions similar to a real level of sun exposure, like dose, irradiance, time, temperature and relative humidity. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Performance Characterization of a Microchannel Liquid/Liquid Heat Exchanger Throughout an Extended Duration Life Test

    Science.gov (United States)

    Sheth, Rubik B.; Stephan, Ryan A.; Hawkins-Reynolds Ebony

    2011-01-01

    Liquid/Liquid Heat Exchangers (L/L HX) are an integral portion of any spacecraft active thermal control system. For this study the X-38 L/L HX was used as a baseline. As detailed in a previous ICES manuscript, NASA paired with Pacific Northwest National Laboratory to develop a Microchannel L/L HX (MHX). This microchannel HX was designed to meet the same performance characteristics as the aforementioned X-38 HX. The as designed Microchannel HX has a 26% and 60% reduction in mass and volume, respectively. Due to the inherently smaller flow passages the design team was concerned about fouling affecting performance during extended missions. To address this concern, NASA has developed a test stand and is currently performing an 18 month life test on the MHX. This report will detail the up-to-date performance of the MHX during life testing.

  12. The interactive effect of leader-member exchange and communication frequency on performance ratings.

    Science.gov (United States)

    Kacmar, K Michele; Witt, L A; Zivnuska, Suzanne; Gully, Stanley M

    2003-08-01

    The authors tested the hypothesis that communication frequency moderates the relationship between leader-member exchange (LMX) and job-performance ratings. In a study of 188 private sector workers, they found that LMX was more strongly related to job-performance ratings among individuals reporting frequent communication with the supervisor than among those reporting infrequent communication. At high levels of LMX, workers reporting frequent communication with the supervisor received more favorable job-performance ratings than did workers reporting infrequent communication. In contrast, at low levels of LMX, workers reporting frequent communication with the supervisor received less favorable job-performance ratings than workers reporting infrequent communication. The authors conducted a 2nd study of 153 public sector workers to provide a constructive replication and found similar results.

  13. Performance prediction of a proton exchange membrane fuel cell using the ANFIS model

    Energy Technology Data Exchange (ETDEWEB)

    Vural, Yasemin; Ingham, Derek B.; Pourkashanian, Mohamed [Centre for Computational Fluid Dynamics, University of Leeds, Houldsworth Building, LS2 9JT Leeds (United Kingdom)

    2009-11-15

    In this study, the performance (current-voltage curve) prediction of a Proton Exchange Membrane Fuel Cell (PEMFC) is performed for different operational conditions using an Adaptive Neuro-Fuzzy Inference System (ANFIS). First, ANFIS is trained with a set of input and output data. The trained model is then tested with an independent set of experimental data. The trained and tested model is then used to predict the performance curve of the PEMFC under various operational conditions. The model shows very good agreement with the experimental data and this indicates that ANFIS is capable of predicting fuel cell performance (in terms of cell voltage) with a high accuracy in an easy, rapid and cost effective way for the case presented. Finally, the capabilities and the limitations of the model for the application in fuel cells have been discussed. (author)

  14. Fouling of proton exchange membrane (PEM) deteriorates the performance of microbial fuel cell.

    Science.gov (United States)

    Xu, Juan; Sheng, Guo-Ping; Luo, Hong-Wei; Li, Wen-Wei; Wang, Long-Fei; Yu, Han-Qing

    2012-04-15

    The fouling characteristics of proton exchange membrane (PEM) in microbial fuel cell (MFC) and the resulting deterioration of MFC performance were explored in this study. It was observed that the ion exchange capacity, conductivity and diffusion coefficients of cations of PEM were reduced significantly after fouling. Imaging analysis coupled with FTIR analysis indicated that the fouling layer attached on PEM consisted of microorganisms encased in extracellular polymers and inorganic salt precipitations. The results clearly demonstrate that PEM fouling deteriorated the performance of MFCs and led to a decrease in electricity generation. Cation transfer limitation might play an important role in the deterioration of MFC performance because of the membrane fouling. This was attributed to the physical blockage of charge transfer in the MFC resulted from the membrane fouling. With the experimental results, the effect of membrane fouling on the electrical generation of MFCs was evaluated. It was found that the decreased diffusion coefficients of cations and cathodic potential loss after membrane fouling contributed mainly to the deterioration of the MFC performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Highly conductive anion exchange membrane for high power density fuel-cell performance.

    Science.gov (United States)

    Ren, Xiaoming; Price, Samuel C; Jackson, Aaron C; Pomerantz, Natalie; Beyer, Frederick L

    2014-08-27

    Anion exchange membrane fuel cells (AEMFCs) are regarded as a new generation of fuel cell technology that has the potential to overcome many obstacles of the mainstream proton exchange membrane fuel cells (PEMFCs) in cost, catalyst stability, efficiency, and system size. However, the low ionic conductivity and poor thermal stability of current anion exchange membranes (AEMs) have been the key factors limiting the performance of AEMFCs. In this study, an AEM made of styrenic diblock copolymer with a quaternary ammonium-functionalized hydrophilic block and a cross-linkable hydrophobic block and possessing bicontinuous phases of a hydrophobic network and hydrophilic conduction paths was found to have high ionic conductivity at 98 mS cm(-1) and controlled membrane swelling with water uptake at 117 wt % at 22 °C. Membrane characterizations and fuel cell tests of the new AEM were carried out together with a commercial AEM, Tokuyama A201, for comparison. The high ionic conductivity and water permeability of the new membrane reported in this study is attributed to the reduced torturosity of the ionic conduction paths, while the hydrophobic network maintains the membrane mechanical integrity, preventing excessive water uptake.

  16. The Affect of Leader - Member Exchange on the Employee Performance on The Role of the Employees’ Perception of Organizational Justice

    Directory of Open Access Journals (Sweden)

    Hakan TURGUT

    2015-12-01

    Full Text Available The purpose of this study can be expressed in two different ways. The first one is two find out the effects of the leader - member exchange on employees organizational justice perception and performances. The second one is to investigate whether or not if organizational justice plays a mediation role on the relationship between leader-member exchange and employee performance. In order to reach our goal, a study has been conducted with the participation of 471 school teachers employed by 20 different schools that provide secondary educational level in Çorum. Results reveal that leader-member exchange has positive and significant effect on organizational justice dimensions (distributive, procedural, interpersonal and informational and employee performance, procedural, interpersonal and informational justice have positive and significant effect on employee performance, also shows that procedural, interpersonal and informational justice have full mediation role on the relationship that occur between leader-member exchange and employee performance.

  17. Hydrolyzed collagen interferes with in vitro photoprotective effectiveness of sunscreens

    Directory of Open Access Journals (Sweden)

    Daniela D'Almeida Peres

    2017-06-01

    Full Text Available ABSTRACT The chronological skin aging is a progressive and natural process with genetic and physiological changes. However, ultraviolet (UV radiation may accelerate the oxidative stress, generating carcinogenesis and photoaging. Natural compounds and their applications are considered a trend in the cosmetic market. The protein-based film-forming compounds play an important role, once it collaborates for the better distribution of sunscreens on the skin. Here we investigated the in vitro photoprotective effectiveness of sunscreens containing the hydrolyzed collagen associated with UVA, UVB and/or inorganic filters. Sunscreens were developed with octocrylene (7.5%, butyl methoxydibenzoylmethane (avobenzone (3.0% and/or titanium dioxide (5.0%, associated or not with the hydrolyzed collagen (3.0%. In vitro photoprotective effectiveness was determined in a Labsphere(r UV2000S by the establishment of the sun protection factor (SPF and critical wavelength (nm values. Physicochemical and organoleptic characteristics were also assayed. The hydrolyzed collagen subjectively improved the formulation sensory characteristics. However, this bioactive compound led to a decrease of the SPF values of the photoprotective formulations containing octocrylene alone and octocrylene + butyl methoxydibenzoylmethane + TiO2. This inadequate interaction may be considered during the development of new sunscreens intended to contain protein-based components.

  18. Foundation Heat Exchanger Final Report: Demonstration, Measured Performance, and Validated Model and Design Tool

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Patrick [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Im, Piljae [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2012-01-01

    (FHX) has been coined to refer exclusively to ground heat exchangers installed in the overcut around the basement walls. The primary technical challenge undertaken by this project was the development and validation of energy performance models and design tools for FHX. In terms of performance modeling and design, ground heat exchangers in other construction excavations (e.g., utility trenches) are no different from conventional HGHX, and models and design tools for HGHX already exist. This project successfully developed and validated energy performance models and design tools so that FHX or hybrid FHX/HGHX systems can be engineered with confidence, enabling this technology to be applied in residential and light commercial buildings. The validated energy performance model also addresses and solves another problem, the longstanding inadequacy in the way ground-building thermal interaction is represented in building energy models, whether or not there is a ground heat exchanger nearby. Two side-by-side, three-level, unoccupied research houses with walkout basements, identical 3,700 ft{sup 2} floor plans, and hybrid FHX/HGHX systems were constructed to provide validation data sets for the energy performance model and design tool. The envelopes of both houses are very energy efficient and airtight, and the HERS ratings of the homes are 44 and 45 respectively. Both houses are mechanically ventilated with energy recovery ventilators, with space conditioning provided by water-to-air heat pumps with 2 ton nominal capacities. Separate water-to-water heat pumps with 1.5 ton nominal capacities were used for water heating. In these unoccupied research houses, human impact on energy use (hot water draw, etc.) is simulated to match the national average. At House 1 the hybrid FHX/HGHX system was installed in 300 linear feet of excavation, and 60% of that was construction excavation (needed to construct the home). At House 2 the hybrid FHX/HGHX system was installed in 360 feet of

  19. Foundation Heat Exchanger Final Report: Demonstration, Measured Performance, and Validated Model and Design Tool

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Patrick [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Im, Piljae [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2012-04-01

    (FHX) has been coined to refer exclusively to ground heat exchangers installed in the overcut around the basement walls. The primary technical challenge undertaken by this project was the development and validation of energy performance models and design tools for FHX. In terms of performance modeling and design, ground heat exchangers in other construction excavations (e.g., utility trenches) are no different from conventional HGHX, and models and design tools for HGHX already exist. This project successfully developed and validated energy performance models and design tools so that FHX or hybrid FHX/HGHX systems can be engineered with confidence, enabling this technology to be applied in residential and light commercial buildings. The validated energy performance model also addresses and solves another problem, the longstanding inadequacy in the way ground-building thermal interaction is represented in building energy models, whether or not there is a ground heat exchanger nearby. Two side-by-side, three-level, unoccupied research houses with walkout basements, identical 3,700 ft{sup 2} floor plans, and hybrid FHX/HGHX systems were constructed to provide validation data sets for the energy performance model and design tool. The envelopes of both houses are very energy efficient and airtight, and the HERS ratings of the homes are 44 and 45 respectively. Both houses are mechanically ventilated with energy recovery ventilators, with space conditioning provided by water-to-air heat pumps with 2 ton nominal capacities. Separate water-to-water heat pumps with 1.5 ton nominal capacities were used for water heating. In these unoccupied research houses, human impact on energy use (hot water draw, etc.) is simulated to match the national average. At House 1 the hybrid FHX/HGHX system was installed in 300 linear feet of excavation, and 60% of that was construction excavation (needed to construct the home). At House 2 the hybrid FHX/HGHX system was installed in 360 feet of

  20. Thermal Performance of a Dual-Channel, Helium-Cooled, Tungsten Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    YOUCHISON,DENNIS L.; NORTH,MART T.

    2000-11-22

    Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion. Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m{sup 2} and reached a maximum surface temperature of 593 C for uniform power loading of 3 kW absorbed on a 2-cm{sup 2} area. An impressive 10 kW of power was absorbed on an area of 24 cm{sup 2}. Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum RTDs for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels. The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m{sup 2} using 50 C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented.

  1. Photosystem II-cyclic electron flow powers exceptional photoprotection and record growth in the microalga Chlorella ohadii.

    Science.gov (United States)

    Ananyev, Gennady; Gates, Colin; Kaplan, Aaron; Dismukes, G Charles

    2017-11-01

    The desert microalga Chlorella ohadii was reported to grow at extreme light intensities with minimal photoinhibition, tolerate frequent de/re-hydrations, yet minimally employs antenna-based non-photochemical quenching for photoprotection. Here we investigate the molecular mechanisms by measuring Photosystem II charge separation yield (chlorophyll variable fluorescence, Fv/Fm) and flash-induced O2 yield to measure the contributions from both linear (PSII-LEF) and cyclic (PSII-CEF) electron flow within PSII. Cells grow increasingly faster at higher light intensities (μE/m2/s) from low (20) to high (200) to extreme (2000) by escalating photoprotection via shifting from PSII-LEF to PSII-CEF. This shifts PSII charge separation from plastoquinone reduction (PSII-LEF) to plastoquinol oxidation (PSII-CEF), here postulated to enable proton gradient and ATP generation that powers photoprotection. Low light-grown cells have unusually small antennae (332 Chl/PSII), use mainly PSII-LEF (95%) and convert 40% of PSII charge separations into O2 (a high O2 quantum yield of 0.06mol/mol PSII/flash). High light-grown cells have smaller antenna and lower PSII-LEF (63%). Extreme light-grown cells have only 42 Chl/PSII (no LHCII antenna), minimal PSII-LEF (10%), and grow faster than any known phototroph (doubling time 1.3h). Adding a synthetic quinone in excess to supplement the PQ pool fully uncouples PSII-CEF from its natural regulation and produces maximum PSII-LEF. Upon dark adaptation PSII-LEF rapidly reverts to PSII-CEF, a transient protection mechanism to conserve water and minimize the cost of antenna biosynthesis. The capacity of the electron acceptor pool (plastoquinone pool), and the characteristic times for exchange of (PQH2)B with PQpool and reoxidation of (PQH2)pool were determined. Copyright © 2017. Published by Elsevier B.V.

  2. Studying the performance of a dehumidifier with adsorbent coated heat exchangers for tropical climate operations

    KAUST Repository

    Oh, Seung Jin

    2016-09-26

    A solid desiccant dehumidifier equipped with adsorbent coated heat exchangers has been developed and investigated experimentally. The main component of the solid desiccant dehumidifier included two heat exchangers that were coated with silica gel regular density (RD) type powder in order to increase water adsorption uptake by improving its heat transfer. A series of experiment were conducted to evaluate two key performance indices, namely, moisture removal capacity and thermal performance, under various operating conditions. Results revealed that the reduction of dehumidification process time by 50% can lead to significant improvement of the mean humidity ratio at outlet up to 9.3 g/kg. The maximum moisture removal was found to decrease from 14.8 to 13.2 g/kg with higher airflow rates arising from the reduced residence time of the process air. It was further observed that the water moisture removal was highly affected by inlet humidity ratio. In addition, marked improvement in thermal performance can be achieved by a lowered hot water regeneration temperature. Copyright © 2016 ASHRAE

  3. The effect of acquisitions on firm performance: Evidence Tehran Stock Exchange

    Directory of Open Access Journals (Sweden)

    Farhad Hanifi

    2015-11-01

    Full Text Available Nowadays, mergers and acquisitions are stated as favorable strategies and as free flows of capital applied by managers for the optimal implementation of resources and assets. Acquisition is associated with a condition where two businesses are placed under one shelter and are run like members of a group or are merged as a single corporate. In mergers, two businesses are combined in a new form based on the mutual interests of both parties. The shares of the two businesses are usually exchanged so that they could take part in the new business as shareholders. In acquisition, a business begins to control another business effectively by purchasing parts of its ownership. The present study explored the impact of acquisition on performance of Iranian target companies listed in Tehran Stock Exchange. The results of testing research hypotheses showed that performance of target companies did not significantly increase after acquisition, suggesting a decreasing trend in the performance of the target companies after acquisition compared with the period before acquisition.

  4. Regional cooperation and performance-based planning and programming in Indiana : a regional models of cooperation peer exchange summary report

    Science.gov (United States)

    2016-05-01

    This report highlights key themes identified at the Regional Cooperation and Performance-Based Planning and Programming in Indiana Peer Exchange held on May 25, 2016 in Indianapolis, Indiana. The Regional Models of Cooperation Initiative, which...

  5. Analysis of urinary oligosaccharides in lysosomal storage disorders by capillary high-performance anion-exchange chromatography-mass spectrometry

    NARCIS (Netherlands)

    Bruggink, Cees; Poorthuis, Ben J. H. M.; Deelder, André M.; Wuhrer, Manfred

    2012-01-01

    Many lysosomal storage diseases are characterized by an increased urinary excretion of glycoconjugates and oligosaccharides that are characteristic for the underlying enzymatic defect. Here, we have used capillary high-performance anion-exchange chromatography (HPAEC) hyphenated to mass spectrometry

  6. Preparation and properties of high performance nanocomposite proton exchange membrane for fuel cell

    Science.gov (United States)

    Lin, Yu-Feng; Yen, Chuan-Yu; Ma, Chen-Chi M.; Liao, Shu-Hang; Hung, Chih-Hung; Hsiao, Yi-Hsiu

    Various spatially enlarged organoclays were prepared by using poly(oxyproplene)-backboned quaternary ammonium salts of various molecular weights M w 230, 400 and 2000 as the intercalating agents for Na +-montmorillonite. The modified MMT was utilized to improve the compatibility with Nafion ®. Sufficient interaction of the modified MMT with Nafion ® was studied by using X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). The performance of the Nafion ®/ m-MMT composite membranes for direct methanol fuel cell (DMFCs) was evaluated in terms of water uptake, ion exchange capacity (IEC), methanol permeability, proton conductivity, and cell performance. The methanol permeability of the composite membrane decreased with the increasing of m-MMT content. The proton conductivity of the membrane was lowered slightly from that of pristine Nafion ® membrane. These results led to an essential improvement in the single-cell performance of DMFCs.

  7. Experimental Investigation of Thermal Performance in a Concentric-Tube Heat Exchanger with Wavy Inner Pipe

    Science.gov (United States)

    Çakmak, Gülşah; Yücel, H. Lütfi; Argunhan, Zeki; Yıldız, Cengiz

    2012-06-01

    In this article, the heat transfer, friction factor, and thermal performance factor characteristics of a concentric-tube heat exchanger are examined experimentally. A wavy inner pipe is mounted in the tube with the purpose of generating swirl flow that would help to increase the heat transfer rate of the tube. The examination is performed for a Reynolds number ranging from 2700 to 8800. An empirical correlation is also formulated to match with experimental data of the Nusselt number using the Wilson plot method. In addition, to obtain the real benefits in using the swirl generator at a constant pumping power, the thermal enhancement factor is also determined. Over the range considered, the increases in the Nusselt number, friction factor, and thermal performance factor are found to be, respectively, about 113 %, 81 %, and 196 % higher than those obtained from a smooth-surface inner pipe.

  8. A review on the performance and modelling of proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Boucetta, A., E-mail: abirboucetta@yahoo.fr; Ghodbane, H., E-mail: h.ghodbane@mselab.org; Bahri, M., E-mail: m.bahri@mselab.org [Department of Electrical Engineering, MSE Laboratory, Mohamed khider Biskra University (Algeria); Ayad, M. Y., E-mail: ayadmy@gmail.com [R& D, Industrial Hybrid Vehicle Applications (France)

    2016-07-25

    Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flows and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.

  9. Performance Analysis of Air Breathing Proton Exchange Membrane Fuel Cell Stack (PEMFCS) At Different Operating Condition

    Science.gov (United States)

    Sunil, V.; Venkata siva, G.; Yoganjaneyulu, G.; Ravikumar, V. V.

    2017-08-01

    The answer for an emission free power source in future is in the form of fuel cells which combine hydrogen and oxygen producing electricity and a harmless by product-water. A proton exchange membrane (PEM) fuel cell is ideal for automotive applications. A single cell cannot supply the essential power for any application. Hence PEM fuel cell stacks are used. The effect of different operating parameters namely: type of convection, type of draught, hydrogen flow rate, hydrogen inlet pressure, ambient temperature and humidity, hydrogen humidity, cell orientation on the performance of air breathing PEM fuel cell stack was analyzed using a computerized fuel cell test station. Then, the fuel cell stack was subjected to different load conditions. It was found that the stack performs very poorly at full capacity (runs only for 30 min. but runs for 3 hours at 50% capacity). Hence, a detailed study was undertaken to maximize the duration of the stack’s performance at peak load.

  10. Effect of nanofluid concentration on two-phase thermosyphon heat exchanger performance

    Directory of Open Access Journals (Sweden)

    Cieśliński Janusz T.

    2016-06-01

    Full Text Available An approach - relaying on application of nanofluid as a working fluid, to improve performance of the two-phase thermosyphon heat exchanger (TPTHEx has been proposed. The prototype heat exchanger consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. Distilled water and nanofluid water-Al2O3 solution were used as working fluids. Nanoparticles were tested at the concentration of 0.01% and 0.1% by weight. A modified Peclet equation and Wilson method were used to estimate the overall heat transfer coefficient of the tested TPTHEx. The obtained results indicate better performance of the TPTHEx with nanofluids as working fluid compared to distilled water, independent of nanoparticle concentration tested. However, increase in nanoparticle concentration results in overall heat transfer coefficient decrease of the TPTHEx examined. It has been observed that, independent of nanoparticle concentration tested, decrease in operating pressure results in evaporation heat transfer coefficient increase.

  11. Analysis of sulfonated compounds by ion-exchange high-performance liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Socher, G; Nussbaum, R; Rissler, K; Lankmayr, E

    2001-03-30

    Ion-exchange high-performance liquid chromatography (HPIEC)-mass spectrometry (MS) was used for the analysis of different sulfonated compounds. HPIEC was performed on an aminopropyl column applying a gradient with increasing concentration of a buffer consisting of ammonium acetate-acetic acid and acetonitrile as the organic modifier. HPIEC is well suited to highly efficient separation of sulfonated compounds and furthermore, due to the volatility of ammonium acetate, the method is also appropriate for LC-MS coupling by the means of either atmospheric pressure chemical ionization or electrospray ionization. The applicability range of HPIEC-MS is demonstrated on the basis of a complex mixture of model substances consisting of sulfonated aromatics and textile dyes largely differing from each other in their structural properties.

  12. Discrete hierarchy of sizes and performances in the exchange-traded fund universe

    Science.gov (United States)

    Vandermarliere, B.; Ryckebusch, J.; Schoors, K.; Cauwels, P.; Sornette, D.

    2017-03-01

    Using detailed statistical analyses of the size distribution of a universe of equity exchange-traded funds (ETFs), we discover a discrete hierarchy of sizes, which imprints a log-periodic structure on the probability distribution of ETF sizes that dominates the details of the asymptotic tail. This allows us to propose a classification of the studied universe of ETFs into seven size layers approximately organized according to a multiplicative ratio of 3.5 in their total market capitalization. Introducing a similarity metric generalizing the Herfindhal index, we find that the largest ETFs exhibit a significantly stronger intra-layer and inter-layer similarity compared with the smaller ETFs. Comparing the performance across the seven discerned ETF size layers, we find an inverse size effect, namely large ETFs perform significantly better than the small ones both in 2014 and 2015.

  13. Enhancement of Oxidative Desulfurization Performance over UiO-66(Zr) by Titanium Ion Exchange.

    Science.gov (United States)

    Ye, Gan; Qi, Hui; Li, Xiaolin; Leng, Kunyue; Sun, Yinyong; Xu, Wei

    2017-07-19

    Oxidative desulfurization is considered to be one of the most promising methods for producing ultra-low-sulfur fuels because it can effectively remove refractory sulfur-containing aromatic compounds under mild conditions. In this work, the oxidative desulfurization performance over UiO-66(Zr) is greatly enhanced by Ti ion exchange. This strategy is not only efficient for UiO-66(Zr) with crystal defects but also for UiO-66(Zr) with high crystallinity. In particular, the performance of UiO-66(Zr) with high crystallinity in the oxidative desulfurization of dibenzothiophene can be improved more than 11-fold, which can be mainly attributed to the introduction of active Ti sites. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Thermal and hydraulic performance of compact brazed plate heat exchangers operating as evaporators in domestic heat pumps

    OpenAIRE

    Claesson, Joachim

    2005-01-01

    This thesis investigates the performance of compact brazed plate heat exchangers (CBE) operating as evaporator in heat pump applications. The thesis, and the performances investigated, has been divided into three main sections; One zone evaporator performance; Two zone evaporator performance; and finally Local performance. The 'One zone evaporator performance' section considers the evaporator as one "black box". It was found that "approaching terminal temperatures" were obtained as low overal...

  15. Examining the Relationship between Leader-Member Exchange (LMX) and Objective Performance within Higher Education: An Exploratory Empirical Study

    Science.gov (United States)

    Peterson, Tim O.; Aikens, Shontarius D.

    2017-01-01

    While the common suggestion in leader-member exchange (LMX) research is that there is a strong relationship between LMX and performance, a closer look at these studies reveal that the performance measures in the majority of studies are primarily subjective in nature such as performance reviews. Relatively few studies examine the LMX-objective…

  16. Employees' goal orientations, the quality of leader-member exchange, and the outcomes of job performance and job satisfaction

    NARCIS (Netherlands)

    Janssen, O.; Van Yperen, N.W.

    As hypothesized, data from 170 employees of a Dutch firm showed that the quality of leader-member exchange mediated positive relationships between a mastery orientation and leader-rated in-role job performance, leader-rated innovative job performance, and job satisfaction. In contrast, a performance

  17. Study of the Relationship between Leader-Member Exchange (LMX) and Individual Objective Performance within a University Learning Community

    Science.gov (United States)

    Aikens, Shontarius D.

    2012-01-01

    The study examined the relationship between leader-member exchange (LMX) and individual objective performance. While the LMX literature suggests a positive correlation between LMX and performance, a closer look at the research examined showed that the performance measurements were based on subjective measurements rather than objective…

  18. Enantioseparations by high-performance liquid chromatography based on chiral ligand-exchange.

    Science.gov (United States)

    Natalini, Benedetto; Sardella, Roccaldo; Ianni, Federica

    2013-01-01

    Chiral ligand-exchange chromatography (CLEC) first described in the late 1960s to early 1970s by Davankov and Rogozhin can be still considered as an elective choice for the direct enantioseparation of compounds endowed with chelating moieties. Among the numerous chelating species that have been evaluated as chiral selectors in ligand-exchange (LE) chromatography, a special role is played by a group of amino acids including proline, hydroxyproline, cysteine, phenylalanine, and penicillamine. More to the point, relevant chromatographic performances are also provided by amino alcohol-based chiral selectors, among which, those carrying a leucinol residue as the basic scaffold are worth to be mentioned. Among the various enantiomer chromatographic separation techniques, CLEC has been exploited in all the main techniques including a chiral mobile phase (CMP), a covalently bound chiral stationary phase (B-CSP), and a coated chiral stationary phase (C-CSP). It is the objective of this chapter to describe selected CLEC applications dealing with the above three distinct approaches.

  19. Performance of amorphous NiNb-based alloys in a proton exchange membrane fuel cell (PEMFC)

    Energy Technology Data Exchange (ETDEWEB)

    Barranco, J.; Pierna, A.R. [Univ. of the Basque Country, San Sebastien (Spain). Dept. of Chemical Engineering and Environment

    2009-04-15

    A study was conducted to investigate the effectiveness of the spray technique of the different amorphous catalysts nickel niobate (NiNb){sub 9}9 platinum (Pt){sub 1}, and NiNb{sub 9}9 platinum (Pt) tin (Sn){sub 1}, obtained by means of the mechanical alloying, on the polymeric membrane. In particular, it examined the deposition of the catalysts on the proton exchange membrane, which is of significant importance for preparing an efficient membrane electrode assembling, which will be part of a hydrogen fuel cell. The effectiveness of spray was studied by determining the efficacy in hydrogen fuel cells. Different particle sizes were used in the catalytic ink. The deposition over the proton exchange membrane of the alloys was carried out using the airbrush technique, a process of painting the polymeric membrane which offers a homogeneous spread of the catalyst and carbon powders over the polymeric membrane. The paper described the experiment and results. The paper included a characterization of the catalysts and catalytic layers, and described the performance of the simple cells. It was concluded that both cells exhibit better behaviour when the hydrogen flow rate is low. 16 refs., 6 figs.

  20. Performance testing of grout-based waste forms for the solidification of anion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, I.L.; Bostick, W.D.

    1990-10-01

    The solidification of spent ion exchanges resins in a grout matrix as a means of disposing of spent organic resins produced in the nuclear fuel cycle has many advantages in terms of process simplicity and economy, but associated with the process is the potential for water/cement/resins to interact and degrade the integrity of the waste form solidified. Described in this paper is one possible solution to preserving the integrity of these solidified waste forms: the encapsulation of beaded anion exchange resins in grout formulations containing ground granulated blast furnace slag, Type I-II (mixed) portland cement, and additives (clays, amorphous silica, silica fume, and fly ash). The results of the study reported herein show the cured waste form tested has a low leach rate for nitrate ion from the resin (and a low leach rate is inferred for Tc-99) and acceptable durability as assessed by the water immersion and freezing/thawing test protocols. The results also suggest a tested surrogate waste form prepared in vinyl ester styrene binder performs satisfactorily against the wetting/drying criterion, and it should offer additional insight into future work on the solidification of spent organic resins. 26 refs., 4 figs., 5 tabs.

  1. Ultrathin Sicopion Composite Cation-Exchange Membranes: Characteristics and Electrodialytic Performance following a Conditioning Procedure

    Directory of Open Access Journals (Sweden)

    Erik Ayala-Bribiesca

    2012-01-01

    Full Text Available The aim of this work was to investigate the properties of Sicopion membranes: an ultrathin (≈20 μm composite cation-exchange membrane (CEM made from sulphonated poly(ether-ether-ketone (SPEEK containing different levels of sulphonic-functionalized silica particles (SFSPs. Sicopion membranes were conditioned according to the French Normalization Association procedure, consisting in a series of acid and alkaline washes, and their electrodialytic characteristics were compared to an existent commercial food-grade membrane (CMX-SB. Electrical conductivity of Sicopion membranes was higher than that of CMX-SB membranes (9.92 versus 6.98 mS/cm, as well as their water content (34.0 versus 27.6%. As the SFSP level was reduced, the ion-exchange capacity (IEC of Sicopion membranes increased. Concerning their electrodialytic performances, Sicopion membranes presented a lower demineralization rate than CMX-SB membranes (35.9 versus 45.5%, due to an OH− leakage through the pores created by dislodging the SFSP particles during the conditioning procedure.

  2. The impact of intellectual capital on firm performance: Evidence from Tehran Stock Exchange

    Directory of Open Access Journals (Sweden)

    Mehran Matinfard

    2015-11-01

    Full Text Available The aim of the present research is to study the relationship between intellect capital components and performance evaluation indicators. For measuring intellectual capital, the study uses Pulic’s method [Pulic, A. (2000. VAIC™–an accounting tool for IC management. International Journal of Technology Management, 20(5-8, 702-714.], which consists of three components of physical capital efficiency, human capital efficiency and structural capital efficiency. In the present study first, the value of the intellectual capital of the companies listed on Tehran Stock Exchange over the period 2006-2012 is calculated. Next, the relationship between the components of intellectual capital and financial return of the companies are evaluated. For calculating the financial performance 8 performance indicators in 5 groups presenting market value, profitability, activity, capital return, orientation on value creation are used. In the present research the statistical method used for data analysis is multiple regression and correlation coefficients. The selected sample of research includes 73 companies in continuous way for a time period of 7 years and the size of the company has been considered as a control variable. The findings indicate a positive and significant relationship between intellectual capital and financial performance of companies and a positive effect of the size of company on availability rate of intellectual capital and financial performance of a company.

  3. Performance evaluation of cryogenic counter-flow heat exchangers with longitudinal conduction, heat in-leak and property variations

    Science.gov (United States)

    Jiang, Q. F.; Zhuang, M.; Zhu, Z. G.; Y Zhang, Q.; Sheng, L. H.

    2017-12-01

    Counter-flow plate-fin heat exchangers are commonly utilized in cryogenic applications due to their high effectiveness and compact size. For cryogenic heat exchangers in helium liquefaction/refrigeration systems, conventional design theory is no longer applicable and they are usually sensitive to longitudinal heat conduction, heat in-leak from surroundings and variable fluid properties. Governing equations based on distributed parameter method are developed to evaluate performance deterioration caused by these effects. The numerical model could also be applied in many other recuperators with different structures and, hence, available experimental data are used to validate it. For a specific case of the multi-stream heat exchanger in the EAST helium refrigerator, quantitative effects of these heat losses are further discussed, in comparison with design results obtained by the common commercial software. The numerical model could be useful to evaluate and rate the heat exchanger performance under the actual cryogenic environment.

  4. Board composition, board size and financial performance of Johannesburg stock exchange companies

    Directory of Open Access Journals (Sweden)

    Munyradadzi Raymond Muchemwa

    2016-11-01

    Full Text Available On the basis of agency theory and resource dependence theory, as well as other corporate governance literature, it is predicted that board composition measured as the ratio of non-executive to executive board members and the number of directors on a firm’s board can be positively related to firm performance. This study seeks to test the predictions of this body of theory and to investigate the form of the empirical relationships among these effects. In so doing, this study tests theory that relates these variables in the context of a developing country, using data from South Africa’s Johannesburg Stock Exchange, over a seven-year period, 2006–2012.

  5. Concentration of ownership and corporate performance: evidence from the Zagreb Stock Exchange

    Directory of Open Access Journals (Sweden)

    Alen Džanić

    2012-03-01

    Full Text Available This study examines the relationship between ownership structure and firm performance using a sample of firms listed on the Zagreb Stock Exchange in period 2003-2009. The results obtained using a panel estimation with fixed effects show a significant negative relationship between the existence of a block holder owning more than 30% of the equity and the value of the firm’s Tobin’s Q. However, if there is a family-type second block holder, the effect disappears. Further, the study gives evidence of the negative impact of the fraction of equity owned by management on labor efficiency confirming the quiet-life hypothesis from Bertrand and Mullainathan (2003. Finally, it is shown that foreign ownership is not significantly better than domestic.

  6. Melanin: a photoprotection for Bacillus thuringiensis based biopesticides.

    Science.gov (United States)

    Sansinenea, Estibaliz; Ortiz, Aurelio

    2015-03-01

    Melanins are negatively-charged, hydrophobic, dark high molecular weight irregular biopolymers, composed of polymerized phenolic and/or indolic compounds. They are produced by most organisms. Bacillus thuringiensis is a Gram-positive, spore-forming, soil bacterium and the most successful biological control agent that produces distinctly shaped crystals during sporulation that have insecticidal activity. However, one of the main disadvantages is that the insecticidal activity of B. thuringiensis formulation is unstable and rapidly loses its activity under field conditions due to UV radiation. Melanin absorbs radiation; therefore photoprotection of B. thuringiensis based on melanin has been studied and is herewith reviewed.

  7. Numerical investigation of conjugate heat transfer and flow performance of a fin and tube heat exchanger with vortex generators

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim

    2017-01-01

    type is chosen and investigated at different angles of attack 0 , ??10 and ??20 with the flow direction. Three-dimensional numerical model is developed and simulations are performed for a Reynolds number range 5000 Re 11000 taking conjugate heat transfer into account. The heat transfer and pressure...... loss characteristics are determined and analyzed for an in-line configuration of a fin and tube heat exchanger. In order to evaluate the enhancement in the performance on an equitable basis, the heat exchanger with plain fin surface is considered as a reference design. Results show that the angle...... of attack of a vortex generator has a significant impact on the volume goodness factor, and enhance the thermal performance of a fin and tube heat exchanger in comparison to the design with plain fin. The vortex generator at an angle of attack ??10 is found to perform superior over the Reynolds number range...

  8. European contribution to heat exchanger design/performance: HTFS research and computer programs. Final report. [SCON4 and CEMP1

    Energy Technology Data Exchange (ETDEWEB)

    Lang, C.; Skrovanek, T.

    1979-01-01

    The performance of selected HTFS computer program in solving example heat exchanger design/performance situations is evaluated. In addition, the specific inputs required by the program are presented to give an idea of the amount of detail the user must supply concerning the heat transfer system. Comments on the versatility of each program and technical details necessary for running each program are also provided. The computer programs examined rate the performance of shell-and-tube type condensers and plate-fin heat exchangers.

  9. A numerical performance assessment of a commercial cardiopulmonary by-pass blood heat exchanger.

    Science.gov (United States)

    Consolo, Filippo; Fiore, Gianfranco B; Pelosi, Alessandra; Reggiani, Stefano; Redaelli, Alberto

    2015-06-01

    We developed a numerical model, based on multi-physics computational fluid dynamics (CFD) simulations, to assist the design process of a plastic hollow-fiber bundle blood heat exchanger (BHE) integrated within the INSPIRE(TM), a blood oxygenator (OXY) for cardiopulmonary by-pass procedures, recently released by Sorin Group Italia. In a comparative study, we analyzed five different geometrical design solutions of the BHE module. Quantitative geometrical-dependent parameters providing a comprehensive evaluation of both the hemo- and thermo-dynamics performance of the device were extracted to identify the best-performing prototypical solution. A convenient design configuration was identified, characterized by (i) a uniform blood flow pattern within the fiber bundle, preventing blood flow shunting and the onset of stagnation/recirculation areas and/or high velocity pathways, (ii) an enhanced blood heating efficiency, and (iii) a reduced blood pressure drop. The selected design configuration was then prototyped and tested to experimentally characterize the device performance. Experimental results confirmed numerical predictions, proving the effectiveness of CFD modeling as a reliable tool for in silico identification of suitable working conditions of blood handling medical devices. Notably, the numerical approach limited the need for extensive prototyping, thus reducing the corresponding machinery costs and time-to-market. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  10. Performance of gas diffusion layer from coconut waste for proton exchange membrane fuel cell

    Science.gov (United States)

    Widodo, H.; Destyorini, F.; Insiyanda, D. R.; Subhan, A.

    2017-04-01

    The performance of Gas Diffusion Layer (GDL) synthesized from coconut waste. Gas Diffusion Layer (GDL), produced from coconut waste, as a part of Proton Exchange Membrane Fuel Cell (PEMFC) component, has been characterized. In order to know the performance, the commercial products were used as the remaining parts of PEMFC. The proposed GDL possesses 69% porosity for diffusion of Hydrogen fuel and Oxygen, as well as for transporting electron. With the electrical conductivity of 500 mS.cm-1, it also has hydrophobic properties, which is important to avoid the reaction with water, with the contact angle of 139°. The 5 × 5 cm2 GDL paper was co-assembled with the catalyst, Nafion membrane, bipolar plate, current collector, end plate to obtain single Stack PEMFC. The performance was examined by flowing fuel and gas with the flow rate of 500 and 1000 ml.min-1, respectively, and analyse the I-V polarization curve. The measurements were carried out at 30, 35, and 40°C for 5 cycles to ensure the repeatability. The results shows that the current density and the maximum power density reaches 203 mA.cm-2 and 143 mW.cm-2, respectively, with a given voltage 0.6 V, at 40°C.

  11. Study on Engineering Design and Cost Performance of Borehole Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Lei Yu

    2015-01-01

    Full Text Available The ground source heat pump (GSHP is an environmentally friendly and energy-efficient technology, and the investigations on the simulation models of borehole heat exchanger (BHE have made progress. However, the researches on engineering design and economic performance based on the simulation models of BHE are a few. This paper firstly describes the interior and exterior heat transfer according to the existing achievements, and the corresponding characteristics of models are explained. Afterwards, the detailed design procedures of BHE size are provided and the cost performance is highlighted. Accordingly, an actual engineering project which employs GSHP system as the air conditioning system is researched; the necessary expenses on BHE, heat pump units, and indoor end equipment are all taken into account. The initial investment, operating cost, and other factors that exert influences on the cost performance are demonstrated. In addition, comparisons between different systems are conducted to show the advantages of GSHP. By means of thermal transfer analysis and the design of engineering project, the practicability, energy saving, and environmental protection of GSHP are brought into play, which means the promotion of this technology is the general trend of development of air condition system.

  12. Comparison of the performance of exact-exchange-based density functional methods.

    Science.gov (United States)

    Liu, Fenglai; Proynov, Emil; Yu, Jian-Guo; Furlani, Thomas R; Kong, Jing

    2012-09-21

    How to describe nondynamic electron correlation is still a major challenge to density functional theory (DFT). Recent models designed particularly for this problem, such as Becke'05 (B05) and Perdew-Staroverov-Tao-Scuseria (PSTS) functionals employ the exact-exchange density, the efficient calculation of which is technically quite challenging. We have recently implemented self-consistently the B05 functional based on an efficient resolution-identity (RI) technique. In this study, we report a self-consistent RI implementation of the PSTS functional. In contrast to its original implementation, our version brings no limitation on the choice of the basis set. We have also implemented the Mori-Sanchez-Cohen-Yang-2 (MCY2) functional, another recent DFT method that includes full exact exchange. The performance of PSTS, B05, and MCY2 is validated on thermochemistry, reaction barriers, and dissociation energy curves, with an emphasis on nondynamic correlation effects in the discussion. All three methods perform rather well in general, B05 and MCY2 being on average somewhat better than PSTS. We include also results with other functionals that represent various aspects of the development in this field in recent years, including B3LYP, M06-HF, M06-2X, ωB97X, and TPSSh. The performance of the heavy-parameterized functionals M06-2X and ωB97X is on average better than that of B05, MCY2, and PSTS for standard thermodynamic properties and reactions, while the latter functionals do better in hydrogen abstraction reactions and dissociation processes. In particular, B05 is found to be the only functional that yields qualitatively correct dissociation curves for two-center symmetric radicals like He(2)(+). Finally, we compare the performance of all these functionals on a strongly correlated exemplary case system, the NO dimer. Only PSTS, B05, and MCY2 describe the system qualitatively correctly. Overall, this new type of functionals show good promise of overcoming some of the

  13. Prenzlau geothermal heat exchanger - technical concept and performance; Erdwaermetiefensonde Prenzlau - technisches Konzept und Betriebserfahrungen

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, D. [KEMA-IEV GmbH, Dresden (Germany); Brossmann, E.; Wetzel, H. [VEAG Berlin (Germany)

    1997-12-01

    The geothermal heat exchanger transfers heat geothermal heat through the metal wall of the outer pipe to the circulating water. The clean water heats up on its way down and is then pumped up again through the insulated inner riser pipe. The heated water is used for district heating. Drilling started on 26 March 1994, and the system was commissioned on 10 November 1994. Today, it supplies heat and warm water to about 1100 apartments. During its first year of operation the Prenzlau geothermal heat exchanger, which is 2800 m deep, covered more than 20 % of the heat demand of the Prenzlau-West district heating grid. The seasonal performance factor in continuous operation of the 500 kW system is between 8 and 12 % of the weather-dependent peak load, with hourly peaks of more than 700 kW. (orig./AKF) [Deutsch] Die Erdwaermetiefensonde nutzt die Waermeuebertragung vom warmen Erdreich durch die Metallwand des Aussenrohrs zum darin zirkulierenden Wasser. Das eingeleitete saubere Wasser erwaermt sich an der aeusseren Rohrwandung auf dem Weg nach unten und wird dann im inneren waermeisolierten Steigrohr an die Oberflaeche befoerdert. Das erwaermte Waser wird in Prenzlau ueber eine Waermepumpe zu Fernwaermezwecken benutzt. Am 26.3.1994 begannen die Bohrarbeiten, und am 10.11.1994 ging die gesamte Anlage in Betrieb, die heute ca. 1100 Wohnungen mit Waerme und Warmwasser versorgt. Die Erdwaermetiefensonde Prenzlau mit einer Tiefe von 2800 m deckte in den ersten beiden Betriebsjahren ueber 20 % des Waermebedarfs des Fernwaermenetzes Prenzlau-West. Die Jahresdauerleistung der Erdwaermetiefensonde mit 500 kW liegt bei 8-12 % der witterungsbedingten Jahreshoechstlast. Die Sonde gestattet Spitzenleistungen im Stundenbereich von mehr als 700 kW. (orig./AKF)

  14. Design and performance evaluation of a microfluidic ion-suppression module for anion-exchange chromatography.

    Science.gov (United States)

    Wouters, Sam; Wouters, Bert; Jespers, Sander; Desmet, Gert; Eghbali, Hamed; Bruggink, Cees; Eeltink, Sebastiaan

    2014-08-15

    A microfluidic membrane suppressor has been constructed to suppress ions of alkaline mobile-phases via an acid-base reaction across a sulfonated poly(tetrafluoroethylene)-based membrane and was evaluated for anion-exchange separations using conductivity detection. The membrane was clamped between two chip substrates, accommodating rectangular microchannels for the eluent and regenerant flow, respectively. Additionally, a clamp-on chip holder has been constructed which allows the alignment and stacking of different chip modules. The response and efficacy of the microfluidic chip suppressor was assessed for a wide range of eluent (KOH) concentrations, using 127 and 183μm thick membranes, while optimizing the flow rate and concentration of the regenerant solution (H2SO4). The optimal operating eluent flow rate was determined at 5μL/min, corresponding to the optimal van-Deemter flow velocity of commercially-available column technology, i.e. a 0.4mm i.d.×250mm long column packed with 7.5μm anion-exchange particles. When equilibrated at 10mM KOH, a 99% decrease in conductivity signal could be obtained within 5min when applying 10mM H2SO4 regenerant at 75μL/min. A background signal as low as 1.2μS/cm was obtained, which equals the performance of a commercially-available electrolytic hollow-fiber suppressor. When increasing the temperature of the membrane suppressor from 15 to 20°C, ion suppression was significantly improved allowing the application of 75mM KOH. The applicability of the chip suppressor has been demonstrated with an isocratic baseline separation of a mixture of seven inorganic ions, yielding plate numbers between 5300 and 10,600 and with a gradient separation of a complex ion mixture. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Performance of Helical Coil Heat Recovery Exchanger using Nanofluid as Coolant

    Directory of Open Access Journals (Sweden)

    Navid Bozorgan

    2015-07-01

    Full Text Available Nanofluids are expected to be a promising coolant condidate in chemical processes for heat transfer system size reduction. This paper focuses on reducing the number of turns in a helical coil heat recovery exchanger with a given heat exchange capacity in a biomass heating plant using γ-Al2O3/n-decane nanofluid as coolant. The nanofluid flows through the tubes and the hot n-hexane flows through the shell. The numerical results show that using nanofluid as coolant in a helical coil heat exchanger can reduce the manufacturing cost of the heat exchanger and pumping power by reducing the number of turns of the coil.

  16. Water Uptake Performance of Hygroscopic Heat and Moisture Exchangers after 24-Hour Tracheostoma Application.

    Science.gov (United States)

    van den Boer, Cindy; Vas Nunes, Jonathan H; Muller, Sara H; van der Noort, Vincent; van den Brekel, Michiel W M; Hilgers, Frans J M

    2014-06-01

    After total laryngectomy, patients suffer from pulmonary complaints due to the shortcut of the upper airways that results in decreased warming and humidification of inspired air. Laryngectomized patients are advised to use a heat and moisture exchanger (HME) to optimize the inspired air. According to manufacturers' guidelines, these medical devices should be replaced every 24 hours. The aim of this study is to determine whether HMEs still function after 24-hour tracheostoma application. Assessment of residual water uptake capacity of used HMEs by measuring the difference between wet and dry core weight. Tertiary comprehensive cancer center. Three hygroscopic HME types were tested after use by laryngectomized patients in long-term follow-up. Water uptake of 41 used devices (including 10 prematurely replaced devices) was compared with that of control (unused) devices of the same type and with a control device with a relatively low performance. After 24 hours, the mean water uptake of the 3 device types had decreased compared with that of the control devices. For only one type was this difference significant. None of the used HMEs had a water uptake lower than that of the low-performing control device. The water uptake capacity of hygroscopic HEMs is clinically acceptable although no longer optimal after 24-hour tracheostoma application. From a functional point of view, the guideline for daily device replacement is therefore justified. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.

  17. Seasonal performance for Heat pump with vertical ground heat exchanger in Riga

    Science.gov (United States)

    Jaundālders, S.; Stanka, P.; Rusovs, D.

    2017-10-01

    Experimental measurements of Seasonal Coefficient of Performance (SCOP) for heating of 160 m2 household in Riga were conducted for operation of brine-water heat pump with vertical ground heat exchangers (GHE). Data regarding heat and electrical power consumption were recorded during three-year period from 2013 to 2016. Vapor compression heat pump has heat energy output of 8 kW. GHE consists of three boreholes. Each borehole is 60 m deep. Data regarding brine temperature for borehole input and output were presented and discussed. As far as house had floor heating, there were presented data about COP for B0/W35 and its dependence from room and outdoor temperature during heating season. Empirical equation was created. Average heat energy consumption during one year for heating was 72 kWh/m2 measured by heat meter. Detected primary energy consumption (electrical energy from grid) was 21 kWh/m2 which resulted in SCOP=3.8. These data were compared with SCOP for air-to-water heat pump in Latvia and available configuration software for heat pumps operation. Good agreement between calculated performance and reported experimental data were founded.

  18. An Experiment to Analyze Performance of Virtual Private Network Approach to Information Exchange between Health Facilities

    Directory of Open Access Journals (Sweden)

    Siphael BETUEL

    2017-06-01

    Full Text Available In developing countries, Tanzania in particular, studies and reports have depicted that there is a strong desire and need for seamless information exchange across health care providing facilities. A limited study conducted in few public and private hospitals has also revealed the same. On the other hand, the eHealth community has failed to effectively take advantage of the advances in technologies to make that desire come true. One potential technology is Virtual Private Network (VPN for which it has been noticed that there is a misconception and lack of innovative initiatives that slow down its uptake in eHealth. This article presents a technical assessment of the VPN technology in Tanzanian context. Primarily, the assessment focused on practicability of the best VPN practices and the perceived user experience performance when VPN is in use. It was observed that the response time dropped significantly as expected. The increase in response time and computer memory utilization is due to security mechanisms that are involved in VPN, the stronger security is used the more performance decreases. However, the increase in response time and computer memory utilization is very small in such a way that users will not be able to notice.

  19. Performance of the CERN PSB at 160 MeV with $H^{-}$ charge exchange injection

    CERN Document Server

    AUTHOR|(CDS)2084247; Santoni, Claudio

    As part of the LHC Injectors Upgrade Project, the CERN PS Booster (PSB) will be upgraded with a H- charge exchange injection system and its injection energy will be raised from 50 MeV to 160 MeV to obtain the beam brightness required for the LHC High-Luminosity Upgrade. Space charge effects like beam losses and transverse emittance blow-up at injection are expected to be the main limitations towards the achievement of the required high brightness. Studies of beam dynamics in presence of space charge in order to evaluate the performances of the PSB after the Upgrade have been performed. The first part of the work consists of measurements in the present machine, to study the effects of space charge and its interplay with resonances and to have a good set of data for code benchmarking. The code chosen for the beam tracking in presence of space charge is PTC-Orbit (and PyOrbit). Necessary numerical convergence studies are presented together with a benchmark with the PSB measurements. Once assessed the code and it...

  20. AUGMENTATION OF RIBS TURBULATORS HEIGHT ON THE HYDROTHERMAL PERFORMANCE OF DOUBLE PIPE HEAT EXCHANGER

    Directory of Open Access Journals (Sweden)

    HUSSAIN H. AL-KAYIEM

    2017-02-01

    Full Text Available Thermal performance of double pipe heat exchanger can be enhanced by imposed turbulence in the annular flow using artificial roughening. This paper presents experimental results on enhancing the heat transfer by artificial roughening using energy promoters installed on the inner surface of the cold flow annulus. An experimental test rig was fabricated having 2.0 m long annular flow test section with 76.2 mm and 34.2 mm outside and inside diameters, respectively. The energy promoters have ribs shape with rectangular cross section. Two cases of rib’s pitch to height ratios, equal to 10 and 15 and three height to hydraulic diameter, equal to 0.0595, 0.083, and 0.107 have been studied. The investigations were carried out at various flow rates within Reynolds number range of 2900 to 21000 in the cold annulus. For each roughening case, the thermal and hydraulic performances wereevaluated by determining Stanton number and the associated pressure drop, respectively. The experimental results showed that enhancement in the heat transfer was combined with a penalty in the pressure drop due to the increase in the friction factor values. The combined hydrothermal enhancement results of the DPHE, in terms of the performance index, indicate that the small height ribs to hydraulic diameter of 0.0595, augmented higher than the large height ribs to hydraulic diameter of 0.107. Hence, it is recommended to use ribs installed on the inner surface of the annulus ribs to hydraulic diameter in the range of 0.06 ± 0.005. Also, it is recommended to investigate further parameters to explore further on the influencing of the ribs on the hydrothermal performance of the DPHE.

  1. Experimental study on heat transfer performance of fin-tube exchanger and PSHE for waste heat recovery

    Science.gov (United States)

    Chen, Ting; Bae, Kyung Jin; Kwon, Oh Kyung

    2018-02-01

    In this paper, heat transfer characteristics of fin-tube heat exchanger and primary surface heat exchanger (PSHE) used in waste heat recovery were investigated experimentally. The flow in the fin-tube heat exchanger is cross flow and in PSHE counter flow. The variations of friction factor and Colburn j factor with air mass flow rate, and Nu number with Re number are presented. Various comparison methods are used to evaluate heat transfer performance, and the results show that the heat transfer rate of the PSHE is on average 17.3% larger than that of fin-tube heat exchanger when air mass flow rate is ranging from 1.24 to 3.45 kg/min. However, the PSHE causes higher pressure drop, and the fin-tube heat exchanger has a wider application range which leads to a 31.7% higher value of maximum heat transfer rate compared to that of the PSHE. Besides, under the same fan power per unit frontal surface, a higher heat transfer rate value is given in the fin-tube heat exchanger.

  2. Performance of single chamber biocatalyzed electrolysis with different types of ion exchange membranes

    NARCIS (Netherlands)

    Rozendal, R.A.; Hamelers, H.V.M.; Molenkamp, R.J.; Buisman, C.J.N.

    2007-01-01

    In this paper hydrogen production through biocatalyzed electrolysis was studied for the first time in a single chamber configuration. Single chamber biocatalyzed electrolysis was tested in two configurations: (i) with a cation exchange membrane (CEM) and (ii) with an anion exchange membrane (AEM).

  3. Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow.

    Science.gov (United States)

    Teng, Tun-Ping; Hung, Yi-Hsuan; Teng, Tun-Chien; Chen, Jyun-Hong

    2011-08-09

    This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration.

  4. How leaders affect followers' work engagement and performance : Integrating Leader−Member Exchange and Crossover Theory

    NARCIS (Netherlands)

    Gutermann, D.; Lehmann-Willenbrock, N.; Boer, D.; Born, M.; Voelpel, S.C.

    Drawing on leader−member exchange and crossover theory, this study examines how leaders’ work engagement can spread to followers, highlighting the role of leader−member exchange as an underlying explanatory process. Specifically, we investigate if leaders who are highly engaged in their work have

  5. Performance analysis of cation and anion exchangers in water treatment plant: an industrial case study

    National Research Council Canada - National Science Library

    Ramzan, Naveed; Feroze, Nadeem; Kazmi, Mohsin; Ashraf, Muhammad Arsalan; Hasan, Sajid

    2012-01-01

    ...% for cation, primary and secondary anion exchangers respectively. The operating time of the water treatment train was significantly increased by achieving adequate capacity utilization of secondary anion exchanger. The low capacity utilization of secondary anion resin due to early silica slippage, has been discussed in the paper.

  6. Performance study of a fin and tube heat exchanger with different fin geometry

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

    2016-01-01

    This study analyses the effect of different fin geometries on the heat transfer and pressure loss characteristics of a fin and tube heat exchanger. A numerical investigation is carried out on liquid–gas type double-finned tube heat exchanger under cross-flow condition. Three different cross...

  7. Performance testing of cross flow heat exchanger operating in the atmosphere of flue gas particulate with vapor condensation

    Directory of Open Access Journals (Sweden)

    Nuntaphan, A.

    2006-05-01

    Full Text Available Performance testing of a cross flow heat exchanger operating under the atmosphere of flue gas particulate from combustion was carried out in this work. This heat exchanger exchanges heat between flue gas from the fuel oil combustion and cold water. The heat exchanger is composed of a spiral finned tube bank having 3 rows and 8 tubes per row with a staggered arrangement. The fin spacings considered are 2.85 and 6.10 mm. The theories of thermodynamics and heat transfer are used for analyzing the performance of this system.In this experiment, the flue gas temperature of 200ºC from combustion having 0.35 kg/s mass flow rate flows along outside surface of the heat exchanger and transfers heat to the 25ºC cooling water having 0.15 kg/s mass flow rate flowing in the tube side. Each experiment uses 750 hr for testing. During the testing, part of flue gas condenses on the heat transfer surface.From the experiment, it was found that the heat transfer rate of both heat exchangers tended to decrease with time while the airside pressure drop increased. These results come from the fouling on the heat transfer surface. Moreover, it is found that the heat exchanger having 2.85 mm fin spacing has an approximately 4 times higher fouling resistance than that of the 6.10 mm fin spacing.In this work a model for calculating the fouling resistance is also developed as a the function of time. The model is developed from that of Kern and Seaton and the mean deviation of the model is 0.789.

  8. Ex vivo water exchange performance and short-term clinical feasibility assessment of newly developed heat and moisture exchangers for pulmonary rehabilitation after total laryngectomy.

    Science.gov (United States)

    van den Boer, Cindy; Muller, Sara H; Vincent, Andrew D; Züchner, Klaus; van den Brekel, Michiel W M; Hilgers, Frans J M

    2014-02-01

    Laryngectomized patients suffer from respiratory complaints due to insufficient warming and humidification of inspired air in the upper respiratory tract. Improvement of pulmonary humidification with significant reduction of pulmonary complaints is achieved by the application of a heat and moisture exchanger (HME) over the tracheostoma. The aim of this study was to determine whether the new Provox HMEs (XM-HME and XF-HME) have a better water exchange performance than their predecessors (R-HME and L-HME, respectively; Atos Medical, Hörby, Sweden). The other aim was to assess the short-term clinical feasibility of these HMEs. The XM-HME and XF-HME were weighed at the end of inspiration and at the end of expiration at different breathing volumes produced by a healthy volunteer. The associations between weight changes, breathing volume and absolute humidity were determined using both linear and non-linear mixed effects models. Study-specific questionnaires and tally sheets were used in the clinical feasibility study. The weight change of the XM-HME is 3.6 mg, this is significantly higher than that of the R-HME (2.0 mg). The weight change of the XF-HME (2.0 mg) was not significantly higher than that of the L-HME (1.8 mg). The absolute humidity values of both XM- and XF-HME were significantly higher than that of their predecessors. The clinical feasibility study did not reveal any practical problems over the course of 3 weeks. The XM-HME has a significantly better water exchange performance than its predecessor (R-HME). Both newly designed HMEs did succeed in the clinical feasibility study.

  9. A Critical Evaluation of the Influence of the Dark Exchange Current on the Performance of Dye-Sensitized Solar Cells

    Science.gov (United States)

    García-Rodríguez, Rodrigo; Villanueva-Cab, Julio; Anta, Juan A.; Oskam, Gerko

    2016-01-01

    The influence of the thickness of the nanostructured, mesoporous TiO2 film on several parameters determining the performance of a dye-sensitized solar cell is investigated both experimentally and theoretically. We pay special attention to the effect of the exchange current density in the dark, and we compare the values obtained by steady state measurements with values extracted from small perturbation techniques. We also evaluate the influence of exchange current density, the solar cell ideality factor, and the effective absorption coefficient of the cell on the optimal film thickness. The results show that the exchange current density in the dark is proportional to the TiO2 film thickness, however, the effective absorption coefficient is the parameter that ultimately defines the ideal thickness. We illustrate the importance of the exchange current density in the dark on the determination of the current–voltage characteristics and we show how an important improvement of the cell performance can be achieved by decreasing values of the total series resistance and the exchange current density in the dark. PMID:28787833

  10. A Critical Evaluation of the Influence of the Dark Exchange Current on the Performance of Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Rodrigo García-Rodríguez

    2016-01-01

    Full Text Available The influence of the thickness of the nanostructured, mesoporous TiO2 film on several parameters determining the performance of a dye-sensitized solar cell is investigated both experimentally and theoretically. We pay special attention to the effect of the exchange current density in the dark, and we compare the values obtained by steady state measurements with values extracted from small perturbation techniques. We also evaluate the influence of exchange current density, the solar cell ideality factor, and the effective absorption coefficient of the cell on the optimal film thickness. The results show that the exchange current density in the dark is proportional to the TiO2 film thickness, however, the effective absorption coefficient is the parameter that ultimately defines the ideal thickness. We illustrate the importance of the exchange current density in the dark on the determination of the current–voltage characteristics and we show how an important improvement of the cell performance can be achieved by decreasing values of the total series resistance and the exchange current density in the dark.

  11. Academic performance and personal experience of local, international, and collaborative exchange students enrolled in an Australian pharmacy program.

    Science.gov (United States)

    Davey, Andrew K; Grant, Gary D; Anoopkumar-Dukie, Shailendra

    2013-09-12

    To assess the academic performance and experiences of local, international, and collaborative exchange students enrolled in a 4-year Australian bachelor of pharmacy degree program. Survey instruments exploring the demographics, background, and academic and cultural experiences of students during the program were administered in 2005 to students in all 4 years. Additionally, grades from each semester of the program for students (406 local, 70 international, 155 exchange) who graduated between 2002 and 2006 were analyzed retrospectively. The main differences found in the survey responses among the 3 groups were in students' motivations for choosing the degree program and school, with international and collaborative exchange students having put more thought into these decisions than local students. The average grades over the duration of the program were similar in all 3 demographic groups. However, local students slightly outperformed international students, particularly at the start of the year, whereas collaborative exchange students' grades mirrored those of local students during the 2 years prior to leaving their home country of Malaysia but more closely mirrored those of international students in the final 2 years after arriving on campus in Australia. Despite differences in academic backgrounds and culture, international and exchange students can perform well compared to local students in a bachelor of pharmacy program and were actually more satisfied than local students with the overall experience. Studying in a foreign country can negatively influence academic grades to a small extent and this is probably related to adjusting to the new environment.

  12. Performance Analysis of Photovoltaic Panels with Earth Water Heat Exchanger Cooling

    Directory of Open Access Journals (Sweden)

    Jakhar Sanjeev

    2016-01-01

    Full Text Available The operating temperature is an important factor affecting the performance and life span of the Photovoltaic (PV panels. The rising temperature can be maintained within certain limit using proper cooling techniques. In the present research a novel system for cooling of PV panels named as Earth Water Heat Exchanger (EWHE is proposed and modelled in transient analysis simulation tool (TRNSYS v17.0 for the conditions of Pilani, Rajasthan (India.The various parameters which include cell temperature, PV power output and cell efficiency are observed with respect to variation in mass flow rate of fluid. Simulation results of the system without cooling show that the maximum PV panel temperature reached up to 79.31 °C with electrical efficiency dropped to 9% during peak sunshine hour. On the other hand, when PV panels are coupled with EWHE system, the panel temperature drops to 46.29 °C with an efficiency improving to 11% for a mass flow rate of 0.022 kg/s. In the end the cooling potential of EWHE is found to be in direct correlation with mass flow rate. The proposed system is very useful for the arid regions of western India which are blessed with high solar insolation throughout the year.

  13. Using adaptive neuro fuzzy inference system (ANFIS) for proton exchange membrane fuel cell (PEMFC) performance modeling

    Energy Technology Data Exchange (ETDEWEB)

    Rezazadeh, S.; Mirzaee, I. [Urmia Univ., Urmia (Iran, Islamic Republic of); Mehrabi, M. [University of Pretoria, Pretoria (South Africa)

    2012-11-15

    In this paper, an adaptive neuro fuzzy inference system (ANFIS) is used for modeling proton exchange membrane fuel cell (PEMFC) performance using some numerically investigated and compared with those to experimental results for training and test data. In this way, current density I (A/cm{sup 2}) is modeled to the variation of pressure at the cathode side P{sup C} (atm), voltage V (V), membrane thickness (mm), Anode transfer coefficient {alpha}{sup an}, relative humidity of inlet fuel RH{sup a} and relative humidity of inlet air RH{sup c} which are defined as input (design) variables. Then, we divided these data into train and test sections to do modeling. We instructed ANFIS network by 80% of numerical validated data. 20% of primary data which had been considered for testing the appropriateness of the models was entered ANFIS network models and results were compared by three statistical criterions. Considering the results, it is obvious that our proposed modeling by ANFIS is efficient and valid and it can be expanded for more general states.

  14. Characterisation of brewpub beer carbohydrates using high performance anion exchange chromatography coupled with pulsed amperometric detection.

    Science.gov (United States)

    Arfelli, Giuseppe; Sartini, Elisa

    2014-01-01

    High performance anion exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD) was optimised in order to quantify mannose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose and maltoheptaose content of beer. The method allows the determination of above mentioned oligosaccharides, in a single chromatographic run, without any pre-treatment. Limit of detection and limit of quantification were suitable for beer. Accuracy and repeatability were good for the entire amount considered. Once optimised HPAEC PAD for the specific matrix, the second goal of this research was to verify the possibility to discriminate beers, depending on their style. The carbohydrates content of brewpub commercial beers was very variable, ranging from 19.3 to 1469mg/L (mannose), 34.5 to 2882mg/L (maltose), 141.9 to 20731mg/L (maltotriose), 168.5 to 7650mg/L (maltotetraose), 20.1 to 2537mg/L (maltopentaose), 22.9 to 3295mg/L (maltohexaose), 8.5 to 2492mg/L (maltoeptaose), even in the same style of beer. However, the carbohydrates content was useful, jointed with other compounds amount, to discriminate different styles of beer. As a matter of fact, principal component analysis put in evidence beer differences considering some fermentation conditions and colour. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Performance Expectations of Closed-Brayton-Cycle Heat Exchangers in 100-kWe Nuclear Space Power Systems

    Science.gov (United States)

    Barrett, Michael J.

    2003-01-01

    Performance expectations of closed-Brayton-cycle heat exchangers to be used in 100-kWe nuclear space power systems were forecast. Proposed cycle state points for a system supporting a mission to three of Jupiter s moons required effectiveness values for the heat-source exchanger, recuperator and rejection exchanger (gas cooler) of 0.98,0.95 and 0.97, respectively. Performance parameters such as number of thermal units (Nm), equivalent thermal conductance (UA), and entropy generation numbers (Ns) varied from 11 to 19,23 to 39 kWK, and 0.019 to 0.023 for some standard heat exchanger configurations. Pressure-loss contributions to entropy generation were significant; the largest frictional contribution was 114% of the heat-transfer irreversibility. Using conventional recuperator designs, the 0.95 effectiveness proved difficult to achieve without exceeding other performance targets; a metallic, plate-fin counterflow solution called for 15% more mass and 33% higher pressure-loss than the target values. Two types of gas-coolers showed promise. Single-pass counterflow and multipass cross-counterflow arrangements both met the 0.97 effectiveness requirement. Potential reliability-related advantages of the cross-countefflow design were noted. Cycle modifications, enhanced heat transfer techniques and incorporation of advanced materials were suggested options to reduce system development risk. Carbon-carbon sheeting or foam proved an attractive option to improve overall performance.

  16. Importance of Electrode Hot-Pressing Conditions for the Catalyst Performance of Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Dhiman, Rajnish; Larsen, Mikkel Juul

    2015-01-01

    The catalyst performance in a proton exchange membrane fuel cell (PEMFC) depends on not only the choice of materials, but also on the electrode structure and in particular on the interface between the components. In this work, we demonstrate that the hot-pressing conditions used during electrode...

  17. A Longitudinal Study of the Moderating Role of Extraversion: Leader-Member Exchange, Performance, and Turnover during New Executive Development

    Science.gov (United States)

    Bauer, Talya N.; Erdogan, Berrin; Liden, Robert C.; Wayne, Sandy J.

    2006-01-01

    Identifying factors that help or hinder new executives in "getting up to speed" quickly and remaining with an organization is vital to maximizing the effectiveness of executive development. The current study extends past research by examining extraversion as a moderator of relationships between leader-member exchange (LMX) and performance,…

  18. The Relationship between Information Exchange Benefits and Performance: the Mediating Effect of Supply Chain Compliance in the Chinese Poultry Chain

    NARCIS (Netherlands)

    Peng, G.; Trienekens, J.H.; Omta, S.W.F.; Wang, W.

    2012-01-01

    This paper aims to examine the relationships between information exchange benefits and company performance, and the mediating effect of supply chain compliance on this relationship. A sample of 165 buying companies and of 96 suppliers were analyzed by partial least square (PLS) path modeling. Five

  19. How leader-member exchange, work engagement and HRM consistency explain Chinese luxury hotel employees’ job performance

    NARCIS (Netherlands)

    Li, X.; Sanders, Karin; Frenkel, S.

    2012-01-01

    This paper provides insights into the relationship between leader-member exchange (LMX) and employee job performance. An integrative model that includes work engagement and human resource management (HRM) consistency, defined as the extent to which various HR practices are viewed as consistent with

  20. Channel geometric scales effect on performance and optimization for serpentine proton exchange membrane fuel cell (PEMFC)

    Science.gov (United States)

    Youcef, Kerkoub; Ahmed, Benzaoui; Ziari, Yasmina; Fadila, Haddad

    2017-02-01

    A three dimensional computational fluid dynamics model is proposed in this paper to investigate the effect of flow field design and dimensions of bipolar plates on performance of serpentine proton exchange membrane fuel cell (PEMFC). A complete fuel cell of 25 cm2 with 25 channels have been used. The aim of the work is to investigate the effect of flow channels and ribs scales on overall performance of PEM fuel cell. Therefore, geometric aspect ratio parameter defined as (width of flow channel/width of rib) is used. Influences of the ribs and openings current collector scales have been studied and analyzed in order to find the optimum ratio between them to enhance the production of courant density of PEM fuel cell. Six kind of serpentine designs have been used in this paper included different aspect ratio varying from 0.25 to 2.33 while the active surface area and number of channels are keeping constant. Aspect ratio 0.25 corresponding of (0.4 mm channel width/ 1.6mm ribs width), and Aspect ratio2.33 corresponding of (0.6 mm channel width/ 1.4mm ribs width. The results show that the best flow field designs (giving the maximum density of current) are which there dimensions of channels width is minimal and ribs width is maximal (Γ≈0.25). Also decreasing width of channels enhance the pressure drop inside the PEM fuel cell, this causes an increase of gazes velocity and enhance convection process, therefore more power generation.

  1. Structural Determinats Underlying Photoprotection in the Photoactive Orange Carotenoid Protein of Cyanobacteria

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Adjele; Kinney, James N.; Zwart, Petrus H.; Punginelli, Claire; D' Haene, Sandrine; Perreau, Francois; Klein, Michael G.; Kirilovsky, Diana; Kerfeld, Cheryl

    2010-04-01

    The photoprotective processes of photosynthetic organisms involve the dissipation of excess absorbed light energy as heat. Photoprotection in cyanobacteria is mechanistically distinct from that in plants; it involves the Orange Carotenoid Protein (OCP), a water-soluble protein containing a single carotenoid. The OCP is a new member of the family of blue light photoactive proteins; blue-green light triggers the OCP-mediated photoprotective response. Here we report structural and functional characterization of the wildtype and two mutant forms of the OCP, from the model organism Synechocystis PCC6803. The structural analysis provides highresolution detail of the carotenoidprotein interactions that underlie the optical properties of the OCP, unique among carotenoid-proteins in binding a single pigment per polypeptide chain. Collectively, these data implicate several key amino acids in the function of the OCP and reveal that the photoconversion and photoprotective responses of the OCP to blue-green light can be decoupled.

  2. Photoprotection through ultrafast charge recombination in photochemical reaction centres under oxidizing conditions

    NARCIS (Netherlands)

    Ma, Fei; Swainsbury, David J. K.; Jones, Michael R.; van Grondelle, Rienk

    2017-01-01

    Engineering natural photosynthesis to address predicted shortfalls in food and energy supply requires a detailed understanding of its molecular basis and the intrinsic photoprotective mechanisms that operate under fluctuating environmental conditions. Long-lived triplet or singlet excited electronic

  3. Cyanobacterial Sunscreen Scytonemin: Role in Photoprotection and Biomedical Research.

    Science.gov (United States)

    Rastogi, Rajesh Prasad; Sonani, Ravi Raghav; Madamwar, Datta

    2015-07-01

    Cyanobacteria are the most promising group of photosynthetic microorganisms capable of producing an array of natural products of industrial importance. Scytonemin is a small hydrophobic alkaloid pigment molecules present in the extracellular sheath of several cyanobacteria as a protective mechanism against short wavelength solar ultraviolet (UV) radiation. It has great efficacy to minimize the production of reactive oxygen species and formation of DNA lesions. The biosynthesis of scytonemin is regulated by different physico-chemical stressors. Scytonemin display multiple roles, functioning as a potent UV sunscreen and antioxidant molecules, and can be exploited in cosmetic and other industries for the development of new cosmeceuticals. Herein, we review the occurrence, biosynthesis, and potential application of scytonemin in photoprotection, pharmaceuticals, and biomedical research.

  4. The performance of one belt and one road exchange rate: Based on improved singular spectrum analysis

    Science.gov (United States)

    Lai, Lin; Guo, Kun

    2017-10-01

    ;One Belt and One Road; strategy in China is on push of foreign trade openness at northwest, southwest and northeast, absorption of the excess capacity and new support for economic increase. However, the fluctuation in RMB exchange rate with the countries along the road is unstable so related Chinese enterprises will face high risk of exchange rate. Precise explanation or prediction for exchange rate has been the challengeable hop point in the international finance. This paper decomposed the One Belt One Road Exchange Rate Index (OBORR) and the RMB Effective Exchange Rate Index (CNYX) into trend term, market fluctuation term and noise term using improved singular spectrum analysis (SSA). It turns out that the increasing velocity of OBORR is greater than that of CNYX in the long term, and there is dynamic lead-lag structure in the medium term. In the short term, the fluctuation range and frequency of OBORR are greater than those of CNYX, which means there will be more exchange rate risks in One Belt and One Road countries.

  5. Leader-Member Exchange, Organization-Based Self-Esteem, and Task Performance-A Life-Stage Perspective-

    OpenAIRE

    鄭,有希

    2013-01-01

    Drawing on the leader-member exchange(LMX)theory and the intelligent career theory, we propose that a subordinates’age moderates the relationship between the quality of LMX and task performance. In addition, the study hypothesizes that organization-based self-esteem(OBSE)mediates the moderating effect of age on the relationship between the LMX quality and subordinate task performance, from the self-esteem perspective.

  6. Analytical Investigation and Improvement of Performance of a Proton Exchange Membrane (Pem) Fuel Cell in Mobile Applications

    OpenAIRE

    Khazaee I.

    2015-01-01

    In this study, the performance of a proton exchange membrane fuel cell in mobile applications is investigated analytically. At present the main use and advantages of fuel cells impact particularly strongly on mobile applications such as vehicles, mobile computers and mobile telephones. Some external parameters such as the cell temperature (Tcell ) , operating pressure of gases (P) and air stoichiometry (λair ) affect the performance and voltage losses in the PEM fuel cell. Because of the exis...

  7. Optimization of Heat Exchangers with Dimpled Surfaces to Improve the Performance in Thermoelectric Generators Using a Kriging Model

    Science.gov (United States)

    Li, Shuai; Wang, Yiping; Wang, Tao; Yang, Xue; Deng, Yadong; Su, Chuqi

    2017-05-01

    Thermoelectric generators (TEGs) have become a topic of interest for vehicle exhaust energy recovery. Electrical power generation is deeply influenced by temperature differences, temperature uniformity and topological structures of TEGs. When the dimpled surfaces are adopted in heat exchangers, the heat transfer rates can be augmented with a minimal pressure drop. However, the temperature distribution shows a large gradient along the flow direction which has adverse effects on the power generation. In the current study, the heat exchanger performance was studied in a computational fluid dynamics (CFD) model. The dimple depth, dimple print diameter, and channel height were chosen as design variables. The objective function was defined as a combination of average temperature, temperature uniformity and pressure loss. The optimal Latin hypercube method was used to determine the experiment points as a method of design of the experiment in order to analyze the sensitivity of the design variables. A Kriging surrogate model was built and verified according to the database resulting from the CFD simulation. A multi-island genetic algorithm was used to optimize the structure in the heat exchanger based on the surrogate model. The results showed that the average temperature of the heat exchanger was most sensitive to the dimple depth. The pressure loss and temperature uniformity were most sensitive to the parameter of channel rear height, h 2. With an optimal design of channel structure, the temperature uniformity can be greatly improved compared with the initial exchanger, and the additional pressure loss also increased.

  8. Effect of some geometric parameters on performance of PF{sup 2} heat exchangers in periodic frosting

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ping [Zhejiang Vocational College of Commerce, Hangzhou, Binwen Road 470 (China); Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States); Hrnjak, P.S. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States)

    2010-03-15

    The thermal performance under conditions of initial frost growth and subsequent refrosting after a defrost is experimentally studied for the parallel flow parallel fin (PF{sup 2}) heat exchanger, a new style of heat exchanger that uses louvered bent fins on flat tubes to enhance water drainage when the flat tubes are horizontal (typically outdoor heat exchanger in heat pump operation). This paper focuses on quantification of the effects of geometry (i.e. fin pitch 12-22 fpi and louver pitch 1.4-2.8 mm) on defrost and refrost times. Eight heat exchangers differing in louver pitch and fin spacing are studied. A series of tests are conducted in search for the best geometry. The effects of geometry on heat transfer (thermal performance) and pressure drop for air face velocities of 0.9, 2, and 3 m/s are determined and used for comparison. Characteristics of initial heat transfer coefficient and pressure drop during the first frosting cycle are reported in terms of Colburn j{sub 0} factor and Fanning friction f{sub 0} factor, as a function of Re{sub L{sub p}} and geometry. The newly developed air-side correlations for PF{sup 2} heat exchangers (Colburn j{sub 0} factor and Fanning friction f{sub 0} factor) predict the test data within rms error of {+-}10%, and with mean deviation of 2.95% and 4.98%, respectively. The correlations are base on a very low Reynolds numbers in the range of 100-620, and 8 PF{sup 2} heat exchangers using 48 experimental data. (author)

  9. Synthesis, structural characterization, and performance evaluation of resorcinol-formaldehyde (R-F) ion-exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    Hubler, T.L.; Franz, J.A.; Shaw, W.J.; Bryan, S.A.; Hallen, R.T.; Brown, G.N.; Bray, L.A.; Linehan, J.C.

    1995-08-01

    The 177 underground storage tanks at the DOE`s Hanford Site contain an estimated 180 million tons of high-level radioactive wastes. It is desirable to remove and concentrate the highly radioactive fraction of the tank wastes for vitrification. Resorcinol-formaldehyde (R-F) resin, an organic ion-exchange resin with high selectivity and capacity for the cesium ion, which is a candidate ion-exchange material for use in remediation of tank wastes. The report includes information on the structure/function analysis of R-F resin and the synthetic factors that affect performance of the resin. CS-100, a commercially available phenol-formaldehyde (P-F) resin, and currently the baseline ion-exchanger for removal of cesium ion at Hanford, is compared with the R-F resin. The primary structural unit of the R-F resin was determined to consist of a 1,2,3,4-tetrasubstituted resorcinol ring unit while CS-100, was composed mainly of a 1,2,4-trisubstituted ring. CS-100 shows the presence of phenoxy-ether groups, and this may account for the much lower decontamination factor of CS-100 for cesium ion. Curing temperatures for the R-F resin were found to be optimal at 105--130C. At lower temperatures, insufficient curing, hence crosslinking, of the polymer resin occurs and selectivity for cesium drops. Curing at elevated temperatures leads to chemical degradation. Optimal particle size for R-F resin is in the range of 20--50 mesh-sized particles. R-F resin undergoes chemical degradation or oxidation which destroys ion-exchange sites. The ion-exchange sites (hydroxyl groups) are converted to quinones and ketones. CS-100, though it has much lower performance for cesium ion-exchange, is significantly more chemically stable than R-F resin. To gamma radiation, CS-100 is more radiolytically stable than R-F resin.

  10. Design and Preliminary Thermal Performance of the Mars Science Laboratory Rover Heat Exchangers

    Science.gov (United States)

    Mastropietro, A. J.; Beatty, John; Kelly, Frank; Birur, Gajanana; Bhandari, Pradeep; Pauken, Michael; Illsley, Peter; Liu, Yuanming; Bame, David; Miller, Jennifer

    2010-01-01

    The challenging range of proposed landing sites for the Mars Science Laboratory Rover requires a rover thermal management system that is capable of keeping temperatures controlled across a wide variety of environmental conditions. On the Martian surface where temperatures can be as cold as -123 degrees Centigrade and as warm as 38 degrees Centigrade, the Rover relies upon a Mechanically Pumped Fluid Loop (MPFL) and external radiators to maintain the temperature of sensitive electronics and science instruments within a -40 degrees Centigrade to 50 degrees Centigrade range. The MPFL also manages significant waste heat generated from the Rover power source, known as the Multi Mission Radioisotope Thermoelectric Generator (MMRTG). The MMRTG produces 110 Watts of electrical power while generating waste heat equivalent to approximately 2000 Watts. Two similar Heat Exchanger (HX) assemblies were designed to both acquire the heat from the MMRTG and radiate waste heat from the onboard electronics to the surrounding Martian environment. Heat acquisition is accomplished on the interior surface of each HX while heat rejection is accomplished on the exterior surface of each HX. Since these two surfaces need to be at very different temperatures in order for the MPFL to perform efficiently, they need to be thermally isolated from one another. The HXs were therefore designed for high in-plane thermal conductivity and extremely low through-thickness thermal conductivity by using aerogel as an insulator inside composite honeycomb sandwich panels. A complex assembly of hand welded and uniquely bent aluminum tubes are bonded onto the HX panels and were specifically designed to be easily mated and demated to the rest of the Rover Heat Recovery and Rejection System (RHRS) in order to ease the integration effort. During the cruise phase to Mars, the HX assemblies serve the additional function of transferring heat from the Rover MPFL to the separate Cruise Stage MPFL so that heat

  11. Performance Measurement Model for the Consumer Industry Listed on Indonesia Stock Exchange: DEA and SFA Approaches

    Directory of Open Access Journals (Sweden)

    T.Handono Eko Prabowo

    2014-08-01

    Full Text Available This  research  attempts  to  provide  performance  measurement  model  for  the  consumer industry listed on Indonesia Stock Exchange (IDX by  using the data envelopment analysis (DEA and the stochastic frontier analysis (SFA. There were 36 panel irms analyzed over the period of 2000-2005 or 216 pooled observations. The output variable was total sales and input variables were labor, inventory, ixed assets and capital. Z-variables are age of the irm, size  of  the  irm,  market  share  and  time  period.  Empirical  indings  reveal  that  the  average technical  eficiency  (mean  TE  for  consumer  industry  was  0.6630.  The  study  indicates  the existence of output slacks (output deicits and input slacks (input wastages in the consumer industry's  operation.  The  study  also  shows  that  the  joint  effect  of  four  z-variables  on  the technical  ineficiencies  of  the  consumer  industry  was  signiicant  although  the  individual effects of one or more variables might not be statistically signiicant. ";} // -->activate javascript

  12. EXCHANGE RATE DIFFERENCES-THE ACCOUNTING TREATMENT AND ITS INFLUENCE ON THE FINANCIAL PERFORMANCE OF AN ECONOMIC ENTITY

    Directory of Open Access Journals (Sweden)

    Nicoleta Cristina MATEI

    2016-06-01

    Full Text Available Currency rate differences arise when there are certain debt rights or obligations in foreign currency of an economic entity which are collected, i.e. paid for at a different course from the one displayed by the Romanian National Bank on the date of their establishment. Such differences, according to the situation, generate expenditure or revenue which affects a company's financial result and, consequently, the accountant result as well. The results registered by an economic entity presented in the Profit and Loss Account provide information about its financial performance. This performance can be influenced by the favorable or unfavorable exchange rate differences existing when an economic entity carries out transactions or has incurred foreign currency loans having a significant share in the total amount of transactions or in capitals. The present paper shows the accounting treatment of the exchange rate differences and its impact on the financial performance.

  13. Probing a Coral Genome for Components of the Photoprotective Scytonemin Biosynthetic Pathway and the 2-Aminoethylphosphonate Pathway

    Directory of Open Access Journals (Sweden)

    Nori Satoh

    2013-02-01

    Full Text Available Genome sequences of the reef-building coral, Acropora digitifera, have been decoded. Acropora inhabits an environment with intense ultraviolet exposure and hosts the photosynthetic endosymbiont, Symbiodinium. Acropora homologs of all four genes necessary for biosynthesis of the photoprotective cyanobacterial compound, shinorine, are present. Among metazoans, these genes are found only in anthozoans. To gain further evolutionary insights into biosynthesis of photoprotective compounds and associated coral proteins, we surveyed the Acropora genome for 18 clustered genes involved in cyanobacterial synthesis of the anti-UV compound, scytonemin, even though it had not previously been detected in corals. We identified candidates for only 6 of the 18 genes, including tyrP, scyA, and scyB. Therefore, it does not appear that Acropora digitifera can synthesize scytonemin independently. On the other hand, molecular phylogenetic analysis showed that one tyrosinase gene is an ortholog of vertebrate tyrosinase genes and that the coral homologs, scyA and scyB, are similar to bacterial metabolic genes, phosphonopyruvate (ppyr decarboxylase and glutamate dehydrogenase (GDH, respectively. Further genomic searches for ppyr gene-related biosynthetic components indicate that the coral possesses a metabolic pathway similar to the bacterial 2-aminoethylphosphonate (AEP biosynthetic pathway. The results suggest that de novo synthesis of carbon-phosphorus compounds is performed in corals.

  14. Probing a Coral Genome for Components of the Photoprotective Scytonemin Biosynthetic Pathway and the 2-Aminoethylphosphonate Pathway

    Science.gov (United States)

    Shoguchi, Eiichi; Tanaka, Makiko; Takeuchi, Takeshi; Shinzato, Chuya; Satoh, Nori

    2013-01-01

    Genome sequences of the reef-building coral, Acropora digitifera, have been decoded. Acropora inhabits an environment with intense ultraviolet exposure and hosts the photosynthetic endosymbiont, Symbiodinium. Acropora homologs of all four genes necessary for biosynthesis of the photoprotective cyanobacterial compound, shinorine, are present. Among metazoans, these genes are found only in anthozoans. To gain further evolutionary insights into biosynthesis of photoprotective compounds and associated coral proteins, we surveyed the Acropora genome for 18 clustered genes involved in cyanobacterial synthesis of the anti-UV compound, scytonemin, even though it had not previously been detected in corals. We identified candidates for only 6 of the 18 genes, including tyrP, scyA, and scyB. Therefore, it does not appear that Acropora digitifera can synthesize scytonemin independently. On the other hand, molecular phylogenetic analysis showed that one tyrosinase gene is an ortholog of vertebrate tyrosinase genes and that the coral homologs, scyA and scyB, are similar to bacterial metabolic genes, phosphonopyruvate (ppyr) decarboxylase and glutamate dehydrogenase (GDH), respectively. Further genomic searches for ppyr gene-related biosynthetic components indicate that the coral possesses a metabolic pathway similar to the bacterial 2-aminoethylphosphonate (AEP) biosynthetic pathway. The results suggest that de novo synthesis of carbon-phosphorus compounds is performed in corals. PMID:23434798

  15. Photoprotective potential of strawberry (Fragaria × ananassa) extract against UV-A irradiation damage on human fibroblasts.

    Science.gov (United States)

    Giampieri, Francesca; Alvarez-Suarez, Josè M; Tulipani, Sara; Gonzàles-Paramàs, Ana M; Santos-Buelga, Celestino; Bompadre, Stefano; Quiles, José L; Mezzetti, Bruno; Battino, Maurizio

    2012-03-07

    Exposure to UV-A radiation is known to induce discrete lesions in DNA and the generation of free radicals that lead to a wide array of skin diseases. Strawberry (Fragaria × ananassa) contains several polyphenols with strong antioxidant and anti-inflammatory activities. Because the major representative components of strawberry are anthocyanins, these may significantly contribute to its properties. To test this hypothesis, methanolic extracts from the Sveva cultivar were analyzed for anthocyanin content and for their ability to protect human dermal fibroblasts against UV-A radiation, as assayed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenytetrazolium bromide and Comet assays. Five anthocyanin pigments were identified using high-performance liquid chromatography-diode array detection-electrospray ionization/mass spectrometry. Moreover, the strawberry extract showed a photoprotective activity in fibroblasts exposed to UV-A radiation, increasing cellular viability, and diminishing DNA damage, as compared to control cells. Overall, our data show that strawberry contains compounds that confer photoprotective activity in human cell lines and may protect skin against the adverse effects of UV-A radiation.

  16. The Effect of Good Corporate Governance and Environmental Performance on Financial Performance of the Company (Studies on Participants of Proper Listed on Indonesia Stock Exchange

    Directory of Open Access Journals (Sweden)

    Abigail Andriana

    2017-05-01

    Full Text Available This research aimed to determine whether the environmental performance and Good Corporate Governance (GCG mechanisms such as managerial ownership, institutional ownership, the proportion of independent commissioners, had effects of the audit committee on financial performance measured by using Return on Equity (ROE. This research used the population of manufacturing company listed on Indonesia Stock Exchange that participated in PROPER 2012/2013 and 2013/2014. Based on the multiple regression analysis, audit committee partially had a significant effect on financial performance, while the others did not. Meanwhile, the analysis result shows that environmental performance and all GCG mechanisms simultaneously have significant effectson financial performance.

  17. The Influences of the Exchange Rate on the Performance of Romanian Trade

    Directory of Open Access Journals (Sweden)

    Gabriela Dobrotă

    2016-01-01

    Full Text Available The unprecedented development of international trade relations has generated the possibility of obtaining a significant part of the GDP of the participating countries in foreign trade. As a result, the issue of competitiveness in international economy has become a major concern to authorities. In the category of factors which are influencing the competitiveness level is registered the volatility of the exchange rate. In this paper there were analyzed the aspects regarding the evolution of Romania's foreign trade and exchange rate, in the context of monetary policy measures. The conclusion is that the development plan of the national economy is determined by the action of a complex of economic, social and political factors, but measures taken by the monetary authorities in relation to the regime of exchange may generate visible effects at this level and thus to the volume of foreign trade relations.

  18. Performance evaluation of heat exchanger for mixed refrigerant J-T cryocooler

    Science.gov (United States)

    Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

    2014-09-01

    In mixed refrigerant Joule-Thomson cryocooler, a multi-component mixture of nitrogen-hydrocarbons undergoes evaporation and condensation process in a helical coiled heat exchanger simultaneously at different pressures. Experimental data and empirical correlations for predicting heat transfer coefficients of evaporating and condensing streams of multi-component mixtures at cryogenic temperatures are unavailable. As a result, design of these heat exchangers is a challenging task. The present work aims to address this challenge. It assesses the existing condensation correlations against the calculated data obtained during experimentation. Experiments are conducted to determine overall heat transfer coefficients along the length of the heat exchanger for various mixtures. The paper studies the applicability of these correlations to the multi-component mixtures at cryogenic temperatures.

  19. Performance evaluation of cross-flow single-phase liquid-to-gas polymer tube heat exchanger

    Science.gov (United States)

    Dewanjee, Sujan; Hossain, Md. Rakibul; Rahman, Md. Ashiqur

    2017-06-01

    Reduced core weight and material cost, higher corrosion resistance are some of the major eye catching properties to study polymers over metal in heat exchanger applications in spite of the former's relatively low thermal conductivity and low strength. In the present study, performance of polymer parallel thin tube heat exchanger is numerically evaluated for cross flow liquid to air applications for a wide range of design and operating parameters such as tube diameter, thickness, fluid velocity and temperature, etc. using Computational Fluid Dynamics (CFD). Among a range of available polymeric materials, those with a moderate to high thermal conductivity and strength are selected for this study. A 90 cm × 1 cm single unit of polymer tubes, with appropriate number of tubes such that at least a gap of 5 mm is maintained in between the tubes, is used as a basic unit and multiple combination in the transverse direction of this single unit is simulated to measure the effect. The tube inner diameter is varied from 2 mm to 4 mm and the pressure drop is measured to have a relative idea of pumping cost. For each inner diameter the thickness is varied from .5 mm to 2.5 mm. The water velocity and the air velocity are varied from 0.4 m/s to 2 m/s and 1 m/s to 5 m/s, respectively. The performance of the polymer heat exchanger is compared with that of metal heat exchanger through and an optimum design for polymer heat exchanger is sought out.

  20. The performance of a new gas to gas heat exchanger with strip fin

    NARCIS (Netherlands)

    Wang, J.; Hirs, Gerard; Rollmann, P.

    1999-01-01

    A compact gas to gas heat exchanger needs large heat transfer areas on both fluid sides. This can be realised by adding secondary surfaces. The secondary surfaces are plate fin, strip fin, and louvered fin, etc. The fins extend the heat transfer surfaces and promote turbulence. This paper presents a

  1. Improving the Performance Of Single Cells In The Design Of Proton Exchange Membrane Fuel Cell (PEMFC) When Using Hydrogen

    OpenAIRE

    - Mulyazmi; Maria Ulfah; Silvi Octavia

    2017-01-01

    A proton Exchange Membrane Fuel Cell (PEMFC) was developed as a potential solution in power supply applications. In this study, the parameter values such as the relative humidity, the temperature, the pressure, the stoichiometric ratio of hydrogen to oxygen and the mass of catalyst used were varied to determine their effects on the single cell performance of PEMFC. The investigation showed that an increase in the temperature from 353 to 363 K resulted in a modest improvement in the single-cel...

  2. Charge Reduction Potentials of Several Refrigerants Based on Experimentally Validated Micro-Channel Heat Exchangers Performance and Charge Model

    OpenAIRE

    Padilla Fuentes, Yadira; Hrnjak, Predrag S.

    2012-01-01

    This paper presents an experimentally validated simulation model developed to obtain accurate prediction of evaporator microchannel heat exchanger performance and charge. Effects of using various correlations are presented and discussed with focus on serpentine microchannel evaporators. Experiments with propane are used to validate the model. The experimentally validated model is used to compare the charge reduction potential of various refrigerants. The procedure for charge reduction analysi...

  3. Phytochemical evaluation and in vitro antioxidant and photo-protective capacity of Calendula officinalis L. leaves

    Directory of Open Access Journals (Sweden)

    V.C.K.N. DEUSCHLE

    2015-01-01

    Full Text Available ABSTRACT The plant Calendula officinalis L. is widely applied due to its medicinal properties, which are mainly dermatological and ornamental. The goal of this study is to assess the phytochemical components in a hydroethanolic extract (HECO from the leaves of Calendula officinalis L. using UV-VIS spectrophotometry and thin layer chromatography (TLC, as well as to identify and quantify the components related to its antioxidant capacity employing high performance liquid chromatographic (HPLC. The antioxidant capacity evaluation was performed using the DPPH method for superoxide and hydroxyl radicals. The photo-protective capacity was evaluated by UVspectrophotometry in order to determine the in vitro Sun Protection Factor(SPF. The results show the plant’s strong antioxidant activity (DPPH and hydroxyl methods, which we believe to be related to the presence of flavonoids (24.67 mg/g, polyphenols (33.90 mg/g, condensed tannins (27.30 mg/g, and the amount of rutin (37.25 mg/g, and quercetin (6.09 mg/g found during the study. The HECO presented a good antioxidant capacity, most likely due to the polyphenols, flavonoids, and tannins in its contents. However, the obtained SPF of 1.89 ± 0.05 does not allow the plant to be classified as a stand-alone sunscreen, and more studies are needed in order to test its ability to enhance sunscreens in existing cosmetic formulations.

  4. Experimental Study on the Airside Performance of Aluminum Heat Exchangers Having Slim Louver Fins

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nae Hyun [Incheon Nat’l Univ., Incheon (Korea, Republic of); Cho, Honggi [Samsung Electronics Daejeon, Suwon (Korea, Republic of)

    2017-09-15

    Recent trends in slim air conditioners require heat exchangers of reduced flow depth. In this study, slim louver fin geometry was obtained using predictive correlations. The deduced geometry yielded 10 mm flow depth, 0.9 mm louver pitch, and 35° louver angle. Samples were made and tests were conducted. The new slim sample yielded 36% higher j factor and 2.3% higher f factor compared with those of the standard sample. This implies that 26% reduction of heat exchanger volume was possible by reducing the flow depth. In addition, the j/f1/3 of the slim sample was 55% larger than that of the standard sample. Furthermore, the results are compared with predictions made using existing correlations.

  5. Ion-Exchange Interdiffusion Model with Potential Application to Long-Term Nuclear Waste Glass Performance

    Energy Technology Data Exchange (ETDEWEB)

    Neeway, James J.; Kerisit, Sebastien N.; Liu, Jia; Zhang, Jiandong; Zhu, Zihua; Riley, Brian J.; Ryan, Joseph V.

    2016-05-05

    Abstract: Ion exchange is an integral mechanism influencing the corrosion of glasses. Due to the formation of alteration layers in aqueous conditions, it is difficult to conclusively deconvolute the process of ion exchange from other processes, principally dissolution of the glass matrix. Therefore, we have developed a method to isolate alkali diffusion that involves contacting glass coupons with a solution of 6LiCl dissolved in functionally inert dimethyl sulfoxide. We employ the method at temperatures ranging from 25 to 150 °C with various glass formulations. Glass compositions include simulant nuclear waste glasses, such as SON68 and the international simple glass (ISG), glasses in which the nature of the alkali element was varied, and glasses that contained more than one alkali element. An interdiffusion model based on Fick’s second law was developed and applied to all experiments to extract diffusion coefficients. The model expands established models of interdiffusion to the case where multiple types of alkali sites are present in the glass. Activation energies for alkali ion exchange were calculated and the results are in agreement with those obtained in glass strengthening experiments but are nearly five times higher than values reported for diffusion-controlled processes in nuclear waste glass corrosion experiments. A discussion of the root causes for this apparent discrepancy is provided. The interdiffusion model derived from laboratory experiments is expected to be useful for modeling glass corrosion in a geological repository when the silicon concentration is high.

  6. Preparation and performance evaluation of novel alkaline stable anion exchange membranes

    Science.gov (United States)

    Irfan, Muhammad; Bakangura, Erigene; Afsar, Noor Ul; Hossain, Md. Masem; Ran, Jin; Xu, Tongwen

    2017-07-01

    Novel alkaline stable anion exchange membranes are prepared from various amounts of N-methyl dipicolylamine (MDPA) and brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). The dipicolylamine and MDPA are synthesized through condensation reaction and confirmed by 1H NMR spectroscopy. The morphologies of prepared membranes are investigated by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy and scanning electron microscopy (SEM). The electrochemical and physical properties of AEMs are tested comprising water uptake (WU), ion exchange capacity (IEC), alkaline stability, linear expansion ratio (LER), thermal stability and mechanical stability. The obtained hydroxide conductivity of MDPA-4 is 66.5 mS/cm at 80 °C. The MDPA-4 membrane shows good alkaline stability, high hydroxide conductivity, low methanol permeability (3.43 × 10-7 cm2/s), higher selectivity (8.26 × 107 mS s/cm3), less water uptake (41.1%) and lower linear expansion (11.1%) despite of high IEC value (1.62 mmol/g). The results prove that MDPA membranes have great potential application in anion exchange membrane fuel cell.

  7. PRIMARY PREVENTION OF MALIGNANT SKIN TUMORS – PHOTOPROTECTION

    Directory of Open Access Journals (Sweden)

    Ana Benedičič - Pilih

    2001-12-01

    Full Text Available Background. The incidence of skin cancer is increasing in the world as well as in our country. Decades of research have increased the understanding of the ethiopathogenetic influences and risk factors for development of malignant skin tumors and stimulated efforts to promote their prevention. There are successes of prevention programs in some places in the world expressing with the reduction of mortality because of the cutaneous malignant melanoma. A primary prevention of a skin cancer attempts to change population knowledge, attitudes and beliefs about sunlight, leading to reduce of sunlight exposure.Conclusions. In this article we are discussing guidelines for photoprevention. The best approach to it is a reduction in the overall exposure to sunlight. The natural protection with the use of shade, clothing and hats is promoted as the best protection. Sunscreens are assumed as an important component of adjuvant photoprotection based on their convenience of use and also on their widespread promotion. While it has been argued that all tanning is a manifestation of skin injury, avoiding of artificial tanning devices is proposed also.

  8. Photoprotective effects of inclusion complexes of fullerenes with polyvinylpyrrolidone.

    Science.gov (United States)

    Murakami, Mio; Hyodo, Sayuri; Fujikawa, Yuuki; Fujimoto, Takahiro; Maeda, Kazuhisa

    2013-08-01

    The outermost surface of the body is covered by the stratum corneum, which is critical for proper skin barrier function. We investigated photoprotective effects of inclusion complexes of fullerenes with polyvinylpyrrolidone (PVP/fullerenes). To examine the cytoprotective activity of PVP/fullerenes against ultraviolet B (UVB) irradiation, we placed a dish with or without PVP/fullerenes on top of dishes containing cultured keratinocytes with or without PVP/fullerenes. Next, we examined the effects of PVP/fullerenes on the ratio of cells with cornified envelopes and transglutaminase-1 expression by real-time polymerase chain reaction and immunohistochemistry. Finally, we examined the barrier recovery effect of PVP/fullerenes solution by measuring transepidermal water loss after tape stripping in humans. UVB irradiation at 40 mJ/cm(2) markedly induced inhibition of keratinocyte proliferation. The inhibition of keratinocyte proliferation was restored only when PVP/fullerenes were present before UVB irradiation in the lower dish with the cells. UVB irradiation decreased the ratio of cells with cornified envelopes and transglutaminase-1 expression; however, the application of PVP/fullerenes reversed this phenomenon. PVP/fullerenes solution significantly promoted the recovery of transepidermal water loss on the second and third days after tape stripping. PVP/fullerenes can be used in cosmetics, especially in those intended to protect photo damage and ameliorate skin barrier perturbations. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Heat transfer performance of water and Nanoencapsulated n-nonadecane based Nanofluids in a double pipe heat exchanger

    Science.gov (United States)

    Doruk, Semahat; Şara, Osman Nuri; Karaipekli, Ali; Yapıcı, Sinan

    2017-06-01

    The heat transfer and pressure drop characteristics for the flow of water, which is base fluid, and nanoencapsulated n-nonadecane based nanofluids in a double pipe heat exchanger were investigated. The results showed that no improvement in overall heat transfer coefficient was observed for the nanofluids containing 0.42% and 0.84% solid volume ratios with reference to the base fluid, while an improvement of about 10% was obtained for the nanofluids containing 1.68% solid volume ratio. It was found that the friction factors for the nanofluids exhibited a slight increase reference to the base fluid. A performance analysis based on constant pumping power was also performed.

  10. A high performance polyamide-based proton exchange membrane fabricated via construction of hierarchical proton conductive channels

    Science.gov (United States)

    Ma, Liying; Cai, Weiwei; Li, Jing; Fan, Kun; Jiang, Yao; Ma, Liang; Cheng, Hansong

    2016-01-01

    A concept of hierarchical proton conductive channel (HPCC) capable of simultaneously boosting proton conductivity and fuel-permeation resistivity is proposed and the HPCC is optimized to improve the performance of the hyperbranched polyamide proton exchange membrane. The HPCC built in-situ in the membrane can be tuned by simply changing two amine groups from the meta-position to the para-position in the monomers. We demonstrate that the small structural difference between the two monomers may result in remarkable differences in mechanical and electrochemical properties upon polymerization, which enable significantly improved performance of direct methanol fuel cells.

  11. Predicting thermal performance of heat exchangers using in-situ testing and statistical correlation: Computer code ST{_}XPERT

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K.P.; Iulianetti, K.M. [Holtec International, Cherry Hill, NJ (United States); Scott, B.H. [Baltimore Gas and Electric Co., Lusby, MD (United States)

    1994-12-31

    This paper describes the methodology to ascertain the heat transfer capability of a tubular heat exchanger from steady state field test data. Periodic assessment of the heat duty capability of heat exchangers utilizing a fluid stream capable of inducing appreciable fouling and deemed to be critical to safety in operating nuclear power plants has become a common practice in the wake of USNRC`s issuance of the Generic Letter 89-13. Since the measured test data invariably have a measure of uncertainty due to bias in the measurement instrumentation and errors in the measuring process and the heat transfer coefficient can only be calculated as an approximate value with an associated uncertainty, the calculation of the fouling factor must utilize concepts from statistics of multivariate random phenomena. For simplicity, and without loss of appreciable accuracy, all variables and measurement parameters are assumed to follow Gaussian probability distribution. The solution process permits and utilizes redundant measurements to improve the quality of the result. Although work was specifically carried out to deal with the thermal performance safety issues raised by the US Nuclear Regulatory Commission in 1989, it can be utilized in the performance assessment of any heat exchanger in any industrial application where in-situ testing is carried out. The methodology described herein is implemented in the computer code ST{_}XPERT, whose features are also described in this paper.

  12. Performance and cost characteristics of multi-electron transfer, common ion exchange non-aqueous redox flow batteries

    Science.gov (United States)

    Laramie, Sydney M.; Milshtein, Jarrod D.; Breault, Tanya M.; Brushett, Fikile R.; Thompson, Levi T.

    2016-09-01

    Non-aqueous redox flow batteries (NAqRFBs) have recently received considerable attention as promising high energy density, low cost grid-level energy storage technologies. Despite these attractive features, NAqRFBs are still at an early stage of development and innovative design techniques are necessary to improve performance and decrease costs. In this work, we investigate multi-electron transfer, common ion exchange NAqRFBs. Common ion systems decrease the supporting electrolyte requirement, which subsequently improves active material solubility and decreases electrolyte cost. Voltammetric and electrolytic techniques are used to study the electrochemical performance and chemical compatibility of model redox active materials, iron (II) tris(2,2‧-bipyridine) tetrafluoroborate (Fe(bpy)3(BF4)2) and ferrocenylmethyl dimethyl ethyl ammonium tetrafluoroborate (Fc1N112-BF4). These results help disentangle complex cycling behavior observed in flow cell experiments. Further, a simple techno-economic model demonstrates the cost benefits of employing common ion exchange NAqRFBs, afforded by decreasing the salt and solvent contributions to total chemical cost. This study highlights two new concepts, common ion exchange and multi-electron transfer, for NAqRFBs through a demonstration flow cell employing model active species. In addition, the compatibility analysis developed for asymmetric chemistries can apply to other promising species, including organics, metal coordination complexes (MCCs) and mixed MCC/organic systems, enabling the design of low cost NAqRFBs.

  13. A Study of Financial Performance and Stock Return in IPO Underpricing Phenomenon on the Indonesia Stock Exchange (IDX

    Directory of Open Access Journals (Sweden)

    Agus Irfani

    2014-08-01

    Full Text Available It is widely believed that financial performance of listed companies on stock exchange might potentially affect long-term stock return. However, the impact of financial performance on underpric-ing is still in debate. The purpose of this study is to examine the effect of financial performance on underpricing at the same period and the effect of both financial performance and underpricing on the long-term stock return on the Indonesia stock exchange (IDX. By employing judgemental sampling method, the sample of this reseach includes 43 underpriced stocks taken from the population of 51 initially public offered stocks on the IDX during 2008-2010. This research uses multiple regression technique to test the hypothesis. This study concludes that not all financial performance ratios affect the underpricing and the long-term stock return in 2011. In addition, this study does not find any em-pirical evidence about the effect of underpricing on the long-term stock return. ";} // -->activate javascript

  14. Performance of water source heat pump system using high-density polyethylene tube heat exchanger wound with square copper wire

    Directory of Open Access Journals (Sweden)

    Xin Wen Zhang

    2015-07-01

    Full Text Available Surface water source heat pump system is an energy-efficient heat pump system. Surface water heat exchanger is an important part of heat pump system that can affect the performance of the system. In order to enhance the performance of the system, the overall heat transfer coefficient (U value of the water exchanger using a 32A square copper coiled high-density polyethylene tube was researched. Comparative experiments were conducted between the performance of the coiled high-density polyethylene tube and the 32A smooth high-density polyethylene tube. At the same time, the coefficient of performance of the heat pump was investigated. According to the result, the U value of the coiled tube was 18% higher than that of the smooth tube in natural convection and 19% higher in forced convection. The coefficient of performance of the heat pump with the coiled tube is higher than that with the smooth tube. The economic evaluation of the coiled tube was also investigated.

  15. Chemical Analysis and Evaluation of Antioxidant, Antimicrobial, and Photoprotective Activities of Schinopsis brasiliensis Engl. (Anacardiaceae

    Directory of Open Access Journals (Sweden)

    Sarah Raquel Gomes de Lima-Saraiva

    2017-01-01

    Full Text Available Schinopsis brasiliensis Engl. is a native plant of Caatinga which has high concentrations of compounds capable of absorbing ultraviolet light, suggesting its potential application for the development of sunscreen preparations. After its identification and collection, this vegetable drug was submitted to a physicochemical analysis through the preparation of ethanolic extract. The phytochemical screening and analysis of extracts were carried out by high-performance liquid chromatography (HPLC evaluation. The antioxidant activity of the extract was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH method and β-carotene bleaching test. Inhibitory hemolytic activity and morphological deformation of erythrocytes induced by H2O2 were also demonstrated and the antimicrobial activity was analyzed by the minimal inhibitory concentration (MIC and minimal bactericidal concentration (MBC method. For the in vitro determination of the sun protection factor (SPF, the spectrophotometric method was used. From the analyses carried out with this species, this plant showed significant results for the antioxidant and antimicrobial activities, as well as sunscreen action. Important flavonoids were identified. These data are an important step for the development of new photoprotective cosmetic with Caatinga species, revealing importance and representing another incentive for the preservation of the species involved and analyzed in the study.

  16. Chemical Analysis and Evaluation of Antioxidant, Antimicrobial, and Photoprotective Activities of Schinopsis brasiliensis Engl. (Anacardiaceae)

    Science.gov (United States)

    de Lima-Saraiva, Sarah Raquel Gomes; Oliveira, Fernanda Granja da Silva; Junior, Raimundo Gonçalves de Oliveira; Araújo, Camila de Souza; de Oliveira, Ana Paula; César, Francine Celise Siqueira

    2017-01-01

    Schinopsis brasiliensis Engl. is a native plant of Caatinga which has high concentrations of compounds capable of absorbing ultraviolet light, suggesting its potential application for the development of sunscreen preparations. After its identification and collection, this vegetable drug was submitted to a physicochemical analysis through the preparation of ethanolic extract. The phytochemical screening and analysis of extracts were carried out by high-performance liquid chromatography (HPLC) evaluation. The antioxidant activity of the extract was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and β-carotene bleaching test. Inhibitory hemolytic activity and morphological deformation of erythrocytes induced by H2O2 were also demonstrated and the antimicrobial activity was analyzed by the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) method. For the in vitro determination of the sun protection factor (SPF), the spectrophotometric method was used. From the analyses carried out with this species, this plant showed significant results for the antioxidant and antimicrobial activities, as well as sunscreen action. Important flavonoids were identified. These data are an important step for the development of new photoprotective cosmetic with Caatinga species, revealing importance and representing another incentive for the preservation of the species involved and analyzed in the study. PMID:29124118

  17. Mesh geometry impact on Micromegas performance with an Exchangeable Mesh prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kuger, F., E-mail: fabian.kuger@cern.ch [CERN, Geneva (Switzerland); Julius-Maximilians-Universität, Würzburg (Germany); Bianco, M.; Iengo, P. [CERN, Geneva (Switzerland); Sekhniaidze, G. [CERN, Geneva (Switzerland); Universita e INFN, Napoli (Italy); Veenhof, R. [Uludağ University, Bursa (Turkey); Wotschack, J. [CERN, Geneva (Switzerland)

    2016-07-11

    The reconstruction precision of gaseous detectors is limited by losses of primary electrons during signal formation. In addition to common gas related losses, like attachment, Micromegas suffer from electron absorption during its transition through the micro mesh. This study aims for a deepened understanding of electron losses and their dependency on the mesh geometry. It combines experimental results obtained with a novel designed Exchangeable Mesh Micromegas (ExMe) and advanced microscopic-tracking simulations (ANSYS and Garfield++) of electron drift and mesh transition.

  18. Understanding on Interface Contribution to the Electrode Performance of Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Grahl-Madsen, L.

    2016-01-01

    The commercialization of proton exchange membrane fuel cells (PEMFCs) is closer to the reality than ever before. Electrode interface development can bring a boost to the last few steps. Here, we explore electrode properties from its interface structure, especially the ionomer phase. Electrodes...... decreased with the increase of the ionomer. The electrode surface studies surprisingly reveal that the ionomer coverage increases linearly with the ionomer loading/content only up to a certain extent (around 30 wt.% in this case); further increase of the ionomer content triggers ionomer agglomeration, which...

  19. Photoprotective effect of botanicals and vitamins: A systematic review of clinical trials.

    Science.gov (United States)

    Tuong, William; Kuo, Sandy; Sivamani, Raja K

    2015-01-01

    Overexposure to solar radiation is a major contributor to skin cancer development and premature skin aging. Botanical extracts and vitamins may represent novel photoprotective agents. We sought to systemically review clinical evidence for the use of botanically derived agents and vitamins as photoprotective agents. We systematically searched Embase and PubMed databases. Two independent reviewers reviewed abstracts for inclusion. Additional relevant studies were identified by a manual review of reference lists. Data from eligible studies were extracted independently and discrepancies were resolved by consensus. A total of 51 studies met inclusion criteria. Limited available evidence indicates that several botanical agents and vitamins in topical or oral forms may have promising photoprotective effects. However, generalizability of results is limited by small sample sizes. Botanical extracts and vitamins may add to the armamentarium of sun-protective agents. Additional high-quality trials are needed to strengthen support for their use.

  20. Effect of chloride impurities on the performance and durability of polybenzimidazole-based high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Ali, Syed Talat; Li, Qingfeng; Pan, Chao

    2011-01-01

    . The performance loss was recovered when switching from the HCl solution back to pure water in the air humidifier. Under an accelerated aging performance test conducted through potential cycling between 0.9 V and 1.2 V, the PBI-based fuel cell initially containing 0.5 NaCl mg cm−2 on the cathode catalyst layer......The effect of chloride as an air impurity and as a catalyst contaminant on the performance and durability of polybenzimidazole (PBI)-based high temperature proton exchange membrane fuel cell (HT-PEMFC) was studied. The ion chromatographic analysis reveals the existence of chloride contaminations...... temperatures in 85% phosphoric acid containing chloride ions showed both increase in oxidation and reduction current densities. The fuel cell performance, i.e. the current density at a constant voltage of 0.4 V and 0.5 V was found to be degraded as soon as HCl was introduced in the air humidifier...

  1. Differential leaf gas exchange performance of mango cultivars infected by different isolates of Ceratocystis fimbriata

    Directory of Open Access Journals (Sweden)

    Wilka Messner da Silva Bispo

    2016-04-01

    Full Text Available ABSTRACT Caused by the vascular fungus Ceratocystis fimbriata, mango wilt is considered to be one of the most serious threats in mango-producing regions worldwide. However, changes in leaf gas exchange level and the mechanisms underlying host responses to this fungal infection remain poorly described. This study aimed to evaluate potential changes in the leaf gas exchange of different mango cultivars (Ubá, Espada, Haden and Tommy Atkins in response to two Brazilian isolates of C. fimbriata (CEBS15 and MSAK16 to non-invasively assess cultivar variability in relation to the basal level of resistance to mango wilt. Both isolates, regardless of the cultivar, caused reductions in stomatal conductance and, thus, a reduction in CO2 assimilation via diffusive limitations. Taking into account the full length of the internal lesion and the radial colonization of the stem tissues, both isolates showed equivalent aggressiveness when inoculated into the Haden and Tommy Atkins cultivars. Conversely, when compared to the CEBS15 isolate of C. fimbriata, the MSAK16 isolate was more aggressive in cv. Espada and less aggressive in cv. Ubá.

  2. Factors influencing the separation of oligonucleotides using reversed-phase/ion-exchange mixed-mode high performance liquid chromatography columns.

    Science.gov (United States)

    Biba, Mirlinda; Jiang, Eileen; Mao, Bing; Zewge, Daniel; Foley, Joe P; Welch, Christopher J

    2013-08-23

    New mixed-mode columns consisting of reversed-phase and ion-exchange separation modes were evaluated for the analysis of short RNA oligonucleotides (∼20mers). Conventional analysis for these samples typically involves using two complementary methods: strong anion-exchange liquid chromatography (SAX-LC) for separation based on charge, and ion-pair reversed-phase liquid chromatography (IP-RPLC) for separation based on hydrophobicity. Recently introduced mixed-mode high performance liquid chromatography (HPLC) columns combine both reversed-phase and ion-exchange modes, potentially offering a simpler analysis by combining the benefits of both separation modes into a single method. Analysis of a variety of RNA oligonucleotide samples using three different mixed-mode stationary phases showed some distinct benefits for oligonucleotide separation and analysis. When using these mixed-mode columns with typical IP-RPLC mobile phase conditions, such as ammonium acetate or triethylammonium acetate as the primary ion-pair reagent, the separation was mainly based on the IP-RPLC mode. However, when changing the mobile phase conditions to those more typical for SAX-LC, such as salt gradients with NaCl or NaBr, very different separation patterns were observed due to mixed-mode interactions. In addition, the Scherzo SW-C18 and SM-C18 columns with sodium chloride or sodium bromide salt gradients also showed significant improvements in peak shape. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Experimental investigation and CFD simulation of multi-pipe earth-to-air heat exchangers (EAHEs flow performance

    Directory of Open Access Journals (Sweden)

    Amanowicz Łukasz

    2017-01-01

    Full Text Available In this paper the experimentally obtained flow characteristics of multi-pipe earth-to-air heat exchangers (EAHEs were used to validate the EAHE flow performance numerical model prepared by means of CFD software Ansys Fluent. The cut-cell meshing and the k-ε realizable turbulence model with default coefficients values and enhanced wall treatment was used. The total pressure losses and airflow in each pipe of multi-pipe exchangers was investigated both experimentally and numerically. The results show that airflow in each pipe of multi-pipe EAHE structures is not equal. The validated numerical model can be used for a proper designing of multi-pipe EAHEs from the flow characteristics point of view. The influence of EAHEs geometrical parameters on the total pressure losses and airflow division between the exchanger pipes can be also analysed. Usage of CFD for designing the EAHEs can be helpful for HVAC engineers (Heating Ventilation and Air Conditioning for optimizing the geometrical structure of multi-pipe EAHEs in order to save the energy and decrease operational costs of low-energy buildings.

  4. Experimental investigation and CFD simulation of multi-pipe earth-to-air heat exchangers (EAHEs) flow performance

    Science.gov (United States)

    Amanowicz, Łukasz; Wojtkowiak, Janusz

    2017-11-01

    In this paper the experimentally obtained flow characteristics of multi-pipe earth-to-air heat exchangers (EAHEs) were used to validate the EAHE flow performance numerical model prepared by means of CFD software Ansys Fluent. The cut-cell meshing and the k-ɛ realizable turbulence model with default coefficients values and enhanced wall treatment was used. The total pressure losses and airflow in each pipe of multi-pipe exchangers was investigated both experimentally and numerically. The results show that airflow in each pipe of multi-pipe EAHE structures is not equal. The validated numerical model can be used for a proper designing of multi-pipe EAHEs from the flow characteristics point of view. The influence of EAHEs geometrical parameters on the total pressure losses and airflow division between the exchanger pipes can be also analysed. Usage of CFD for designing the EAHEs can be helpful for HVAC engineers (Heating Ventilation and Air Conditioning) for optimizing the geometrical structure of multi-pipe EAHEs in order to save the energy and decrease operational costs of low-energy buildings.

  5. Optimized design of high performance heat exchangers; Optimierter Entwurf von Hochleistungswaermeuebertragern

    Energy Technology Data Exchange (ETDEWEB)

    Tandogan, E.

    2001-07-01

    A software for prediction and design of industrial VEHE's (vortex enhanced heat exchanger) is developed. Flow charts of the VEHE design software are given in Figs. 1a and b. Fig. 1a is applicable in case of periodic flow, while Fig 1b annotates the procedure for developing flow conditions. The types and mass flow rates of both heat exchanging fluids, the inlet temperatures, and the required heat load of the apparatus are the input data for the operating conditions. The configuration of the heat transfer surface is chosen from a data bank established for this purpose. The data bank includes smooth surfaces as circular tubes and flat plates and enhanced surfaces, in particular: - plates bearing winglet type vortex generators for heat transfer augmentation, - fin-and-tube configurations without and with vortex generators, - corrugated plates, and in particular - three vortex enhanced configurations selected within the present project. Most of the enhanced surface configurations, except the three ones selected in this project, have been investigated at the RUB. Transfer features of these surfaces are given as Colburn factor and (apparent) friction factor respectively, both being functions of the Reynolds number. (orig.) [German] Verschiedene Uebertragungsflaechen mit Wirbelerzeugern, deren Waermeuebergangsverhalten und Duckverluste bekannt sind, wurden fuer Betrieb mit jeweils minimierten Kosten untersucht bzw. miteinander verglichen. Fuer die Beurteilung der Flaechenkonfigurationen ist als gemeinsamer Referenzfall die hydrodynamisch voll entwickelte ebene Spaltstroemung mit der kostenguenstigsten Reynolds-Zahl gewaehlt worden. Naeher untersucht wurden vor allem drei Konfigurationen, die im Rahmen des EU-Projekts 'Vortex Enhanced Heat Exchangers (VEHE)' fuer industrielle Anwendungen ausgewaehlt wurden. Fuer jeden Flaechentyp ergeben sich bestimmte Stroemungsgeschwindigkeiten beider Fluide, welche minimale Kosten der Uebertragungsflaeche und der

  6. Evaluation of Cathode Gas Composition and Temperature Influences on Alkaline Anion Exchange Membrane Fuel Cell (AAEMFC Performance

    Directory of Open Access Journals (Sweden)

    Topal Leyla

    2014-02-01

    Full Text Available The effects of different temperatures (55, 65, 75 and 85 °C and cathode gas compositions (O2, synthetic air, air and 90% synthetic air+10% CO2 on alkaline anion exchange membrane fuel cell (AAEMFC were evaluated. Membrane electrode assemblies (MEA were fabricated using commercial anion exchange membrane (AEM in OH- form and Pt catalyst. Polarization curves and voltage responses during constant current were performed in order to describe the influences of temperature and gas composition on the AAEMFC performance. The experimental results showed that the fuel cell performance increases with elevating temperatures for all applied gas compositions. Highest power density of 34.7 mW cm-2 was achieved for pure O2 as cathode feed. A decrease to 20.3 mW cm-2 was observed when cathode gas composition was changed to synthetic air due to reduction of the O2 partial pressure. The presence of CO2 in atmospheric air applied to the cathode stream caused a further drop of the maximum power density to 15.2 mW cm-2 driven by neutralization of OH- ions with CO2.

  7. Performance of organic-inorganic hybrid anion-exchange membranes for alkaline direct methanol fuel cells

    Science.gov (United States)

    Xiong, Ying; Liu, Qing Lin; Zhu, Ai Mei; Huang, Si Meng; Zeng, Qing Hua

    A series of organic-inorganic membranes were prepared through sol-gel reaction of quaternized poly(vinyl alcohol) (QAPVA) with different contents of tetraethoxysilanes (TEOS) for alkaline direct methanol fuel cells. These hybrid membranes are characterized by FTIR, X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDXA) and thermo gravimetric analysis (TGA). The ion exchange content (IEC), water content, methanol permeability and conductivity of the hybrid membranes were measured to evaluate their applicability in fuel cells. It was found that the addition of silica enhanced the thermal stability and reduced the methanol permeability of the hybrid membranes. The hybrid membrane M-5, for which the silica content was 5 wt%, showed the lowest methanol permeability and the highest ion conductivity among the three hybrid membranes. The ratio of conductivity to methanol permeability of the membrane M-5 indicated that it had a high potential for alkaline direct methanol fuel cell applications.

  8. Pengaruh Modifikasi Heat Exchanger Tipe Concentric Tube Terhadap Performance Sistem Refrigerasi Cascade

    Directory of Open Access Journals (Sweden)

    Jhona Purnama Putra

    2014-03-01

    Full Text Available Dalam beberapa bidang industri seperti pengawetan makanan, perminyakan, pengolahan bahan-bahan kimia dan pendinginan setempat (spot cooling pada industri baja dibutuhkan kondisi ruangan yang sangat rendah berkisar antara -30°C hingga -60°C. Maka dari itu digunakanlah sistem refrigerasi cascade yang disusun atas dua stage yaitu high dan low. Dimana kedua stage ini digabungkan menjadi satu oleh sebuah heat exchanger yang melakukan perpindahan kalor dari kondensor low stage menuju evaporator high stage. pada penelitian terdahulu alat penukar panas yang digunakan yaitu alat penukar panas tipe concentric tube masih menunjukan performa yang belum baik kepada sistem refrigerasi cascade. Penelitian dilakukan dengan memodifikasi alat penukar panas dan menganalisa performa sistem setelah dilakukannya modifikasi penambahan panjang pada alat penukar panas, dengan fluida kerja refrigeran Musicool-22 di High Stage dan R-404A di Low Stage. Setelah perancangan alat selesai, dilakukan eksperimen pada sistem tersebut dengan variasi beban pendinginan menggunakan electric heater di evaporator Low Stage sebesar 0 (tanpa beban, 6, 16, 40, 60, dan 98 Watt.. Hasil dari studi eksperimen ini menunjukkan nilai-nilai optimum yang didapatkan yaitu pada pembebanan 60 Watt dengan Qevap = 0,599 kW, COP cascade = 0,968 dan temperatur di dalam cooling box sebesar -30,1°C serta nilai-nilai maksimum dari performa sistem refrigerasi cascade pada beban 98 Watt yaitu kapasitas pendinginan maksimum pada sistem Low Stage adalah 0,60654 kW, kerja maksimum kompresor pada sistem High Stage 0,1711 kW dan Low Stage 0,4432 kW, nilai COP cascade maksimum 0,9969, efek refrigerasi maksimum pada Low Stage 137,85 kJ/kg, HRR maksimum pada Low Stage 1,731. Kemudian diperoleh nilai effectiveness cascade heat exchanger tertinggi 0,922 dan terendah 0,912 serta nilai NTU tertinggi 7,1800 dan terendah 6,4121.

  9. Investigating the effects of proton exchange membrane fuel cell conditions on carbon supported platinum electrocatalyst composition and performance

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Anant; Artyushkova, Kateryna; Atanassov, Plamen; Colbow, Vesna; Dutta, Monica; Harvey, Davie; Wessel, Silvia

    2011-12-01

    Changes that carbon-supported platinum electrocatalysts undergo in a proton exchange membrane fuel cell environment were simulated by ex situ heat treatment of catalyst powder samples at 150 C and 100% relative humidity. In order to study modifications that are introduced to chemistry, morphology, and performance of electrocatalysts, XPS, HREELS and three-electrode rotating disk electrode experiments were performed. Before heat treatment, graphitic content varied by 20% among samples with different types of carbon supports, with distinct differences between bulk and surface compositions within each sample. Following the aging protocol, the bulk and surface chemistry of the samples were similar, with graphite content increasing or remaining constant and Pt-carbide decreasing for all samples. From the correlation of changes in chemical composition and losses in performance of the electrocatalysts, we conclude that relative distribution of Pt particles on graphitic and amorphous carbon is as important for electrocatalytic activity as the absolute amount of graphitic carbon present

  10. Investigating the effects of proton exchange membrane fuel cell conditions on carbon supported platinum electrocatalyst composition and performance

    Energy Technology Data Exchange (ETDEWEB)

    A. Patel; K. Artyushkova; P. Atanassov; V. Colbow; M. Dutta; D. Harvey; S. Wessel

    2012-04-30

    Changes that carbon-supported platinum electrocatalysts undergo in a proton exchange membrane fuel cell environment were simulated by ex situ heat treatment of catalyst powder samples at 150 C and 100% relative humidity. In order to study modifications that are introduced to chemistry, morphology, and performance of electrocatalysts, XPS, HREELS and three-electrode rotating disk electrode experiments were performed. Before heat treatment, graphitic content varied by 20% among samples with different types of carbon supports, with distinct differences between bulk and surface compositions within each sample. Following the aging protocol, the bulk and surface chemistry of the samples were similar, with graphite content increasing or remaining constant and Pt-carbide decreasing for all samples. From the correlation of changes in chemical composition and losses in performance of the electrocatalysts, we conclude that relative distribution of Pt particles on graphitic and amorphous carbon is as important for electrocatalytic activity as the absolute amount of graphitic carbon present

  11. A model for predicting the thermal-hydraulic performance of louvered-fin, flat-tube heat exchangers under frosting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Y.; Jacobi, A.M. [Department of Mechanical Science and Engineering, University of Illinois, 1206 West Green Street, Urbana, IL 61801 (United States)

    2010-03-15

    Correlations and a model are developed to predict the time-varying performance of folded-louvered-fin, microchannel heat exchangers. The model utilizes the correlations developed from the experimental data and incorporates a sub-model for frost properties. The model successfully predicts the heat transfer performance of the heat exchangers studied, but its ability to predict the pressure-drop behavior needs further improvement. The model can be used to evaluate geometry effects on the frosting behavior of the louvered-fin, microchannel heat exchangers, and can be easily generalized to other applications with simultaneous heat and mass transfer. (author)

  12. Suppressing Shuttle Effect Using Janus Cation Exchange Membrane for High-Performance Lithium-Sulfur Battery Separator.

    Science.gov (United States)

    Li, Zhen; Han, Yu; Wei, Junhua; Wang, Wenqiang; Cao, Tiantian; Xu, Shengming; Xu, Zhenghe

    2017-12-27

    Suppressing the shuttle effect of polysulfide ions to obtain high durability and good electrochemical performance is of great concern in the field of lithium-sulfur batteries. To address this issue, a Janus membrane consisting of an ultrathin dense layer and a robust microporous layer is fabricated using cation exchange resin. Different from the composite membranes made from polyolefin membranes, the multiple layers of the Janus membrane in this study are synchronously generated by one step, getting rid of the additional complex coating processes. Excellent overall performance is obtained by the cooperation of multiple factors. The excellent ionic selectivity of cation exchange resin renders a great suppression of the shuttle effect, endowing the lithium-sulfur battery with high Coulombic efficiency of 92.0-99.0% (LiNO3-free electrolyte). The ultrathin property of a dense layer renders a low ionic resistance, resulting in 60% higher discharge capacity over the entire C-rates (versus the control sample with Celgard 2400 membrane). The robust macroporous layer supports the ultrathin layer to achieve a free-standing property, ensuring the usability of the Janus membrane.

  13. Development of a High-Performance Fin-and-Tube Heat Exchanger with Vortex Generators for a Vending Machine

    Science.gov (United States)

    Iwasaki, Masamichi; Saito, Hiroshi; Mochizuki, Sadanari; Murata, Akira

    The effect of delta-wing-vortex generators (combination of a delta wing and a delta winglet pair) on the heat transfer performance of fin-and-tube heat exchangers for vending machines has been investegated. Flow visualizations, numerical simulations and heat transfer experiments were conducted to find an optimum geometrical shape and arrangement of the vortex generators. Maximum heat transfer enhancement was achieved by the combination of (a) the delta wing with the apex angle of 86 degrees and (b) the delta winglet pair with the inline angle of 45 degrees. In relatively low Reynolds number range, about 40 % increase in heat transfer coefficient was attained with the above mentioned combination of the vortex generators compared to the ordinary heat exchangers with plain fins. It was revealed that the heat transfer enhancement was attributed to (1) the longitudinal vortexes generated by the delta wing and (2) the reduction of wake area behind the tube. It was also found that an increase in the apex angle of the delta wing brought about heat transfer enhancement, and the scale as well as the streggth of the induced longitudinal vortices played an important role in the heat transfer performance.

  14. In vivo photoprotective effects of cosmetic formulations containing UV filters, vitamins, Ginkgo biloba and red algae extracts.

    Science.gov (United States)

    Mercurio, D G; Wagemaker, T A L; Alves, V M; Benevenuto, C G; Gaspar, L R; Maia Campos, P M B G

    2015-12-01

    The aim of this study was to assess the photoprotective effects of cosmetic formulations containing UV filters, red algae, Porphyra umbilicalis, extracts and combinations of the extract with vitamins and Ginkgo biloba through the use of in vivo preclinical studies. For this study, 4 groups of 4 hairless mice each were treated with topical formulations applied on the dorsum for 5 days as follows: group 1 - control (no treatment); group 2 - application of the formulation F (sunscreen formulation containing only UV filters); group 3 - application of the formulation FA (sunscreen formulation with red algae extract); and group 4 - application of the formulation FVGA (sunscreen formulation with red algae extract, G. biloba and vitamins A, C and E). The effects of these formulations were evaluated by determining the transepidermal water loss (TEWL) and erythema index. Apoptosis was detected by immunohistochemical staining with anti-p53 and anti-caspase-3 antibodies. The results showed that the formulations protected the skin from erythema when exposed to UV radiation. The group that received the formulation FVGA presented a greater TEWL than did the other groups, suggesting that this formulation was involved in cell renewal. Immunohistochemical analysis showed that UV radiation caused an increase in the expression of p53 and active caspase-3, confirming that the damage caused by UV radiation exposure led to apoptosis. The application of all formulations studied resulted in a statistically significant reduction in the expression of p53 and caspase-3, with a more pronounced effect observed following treatment with FA. In conclusion, extracts from the red algae P. umbilicalis could be considered effective ingredients to be used in sunscreen formulations. The combination of vitamins A, E, C and G. biloba along with red algae extracts can improve significantly the performance of the sunscreens, preventing UV-induced DNA damage and inflammation. Thus, they should be considered

  15. Evaluating Kuala Lumpur stock exchange oriented bank performance with stochastic frontiers

    Science.gov (United States)

    Baten, M. A.; Maznah, M. K.; Razamin, R.; Jastini, M. J.

    2014-12-01

    Banks play an essential role in the economic development and banks need to be efficient; otherwise, they may create blockage in the process of development in any country. The efficiency of banks in Malaysia is important and should receive greater attention. This study formulated an appropriate stochastic frontier model to investigate the efficiency of banks which are traded on Kuala Lumpur Stock Exchange (KLSE) market during the period 2005-2009. All data were analyzed to obtain the maximum likelihood method to estimate the parameters of stochastic production. Unlike the earlier studies which use balance sheet and income statements data, this study used market data as the input and output variables. It was observed that banks listed in KLSE exhibited a commendable overall efficiency level of 96.2% during 2005-2009 hence suggesting minimal input waste of 3.8%. Among the banks, the COMS (Cimb Group Holdings) bank is found to be highly efficient with a score of 0.9715 and BIMB (Bimb Holdings) bank is noted to have the lowest efficiency with a score of 0.9582. The results also show that Cobb-Douglas stochastic frontier model with truncated normal distributional assumption is preferable than Translog stochastic frontier model.

  16. Evaluating Kuala Lumpur stock exchange oriented bank performance with stochastic frontiers

    Energy Technology Data Exchange (ETDEWEB)

    Baten, M. A.; Maznah, M. K.; Razamin, R.; Jastini, M. J. [School of Quantitative Sciences, Universiti Utara Malaysia 06010, Sintok, Kedah (Malaysia)

    2014-12-04

    Banks play an essential role in the economic development and banks need to be efficient; otherwise, they may create blockage in the process of development in any country. The efficiency of banks in Malaysia is important and should receive greater attention. This study formulated an appropriate stochastic frontier model to investigate the efficiency of banks which are traded on Kuala Lumpur Stock Exchange (KLSE) market during the period 2005–2009. All data were analyzed to obtain the maximum likelihood method to estimate the parameters of stochastic production. Unlike the earlier studies which use balance sheet and income statements data, this study used market data as the input and output variables. It was observed that banks listed in KLSE exhibited a commendable overall efficiency level of 96.2% during 2005–2009 hence suggesting minimal input waste of 3.8%. Among the banks, the COMS (Cimb Group Holdings) bank is found to be highly efficient with a score of 0.9715 and BIMB (Bimb Holdings) bank is noted to have the lowest efficiency with a score of 0.9582. The results also show that Cobb-Douglas stochastic frontier model with truncated normal distributional assumption is preferable than Translog stochastic frontier model.

  17. Support from the top: supervisors' perceived organizational support as a moderator of leader-member exchange to satisfaction and performance relationships.

    Science.gov (United States)

    Erdogan, Berrin; Enders, Jeanne

    2007-03-01

    The authors hypothesized that supervisors' perceived organizational support (POS) would moderate the relationships between leader-member exchange (LMX), job satisfaction, and job performance. On the basis of social exchange theory, supervisors' exchanges with the organization and subordinates should be interconnected. The authors expected that supervisors with high POS would have more resources to exchange with subordinates. Thus, supervisor POS should enhance the relationships between LMX and job satisfaction and LMX and job performance for subordinates. Hierarchical linear modeling analysis provided support for the hypotheses in a sample of 210 subordinates and 38 supervisors of a grocery store chain. The positive relationship between LMX and job satisfaction was stronger when supervisors had high POS. Moreover, LMX was related to performance only when supervisors had high POS. (c) 2007 APA, all rights reserved.

  18. Effect of geometrical uncertainties on the performance of heat exchangers using an efficient POD-based model reduction technique

    Science.gov (United States)

    Abraham, S.; Ghorbaniasl, G.; Raisee, M.; Lacor, C.

    2016-06-01

    The present paper aims at assessing the effect of manufacturing tolerances on the performance of heat exchangers. To this end, a two-dimensional square rib-roughened cooling channel is considered and uncertainties are introduced along the rib profile, using a Karhunen-Loéve expansion including 20 uncertainties. In order to break the curse of dimensionality and keep the overall computational cost within acceptable limits, an efficient uncertainty quantification strategy is followed. A sensitivity analysis is first performed on a coarse grid, enabling the most important dimension to be identified and to remove the ones which have not any significant effect on the output of interest. Afterwards, an efficient Proper Orthogonal Decomposition based dimension reduction technique is implemented in order to propagate uncertainties through the CFD model. It is shown that heat transfer predictions are strongly affected by geometrical uncertainties while no significant effect was found for the pressure drop.

  19. SIMULATION OF POROSITY AND PTFE CONTENT IN GAS DIFFUSION LAYER ON PROTON EXCHANGE MEMBRANE FUEL CELL PERFORMANCE

    Directory of Open Access Journals (Sweden)

    NUR H. MASLAN

    2016-01-01

    Full Text Available Numerous research and development activities have been conducted to optimize the operating parameters of a proton exchange membrane fuel cell (PEMFC by experiments and simulations. This study explains the development of a 3D model by using ANSYS FLUENT 14.5 to determine the optimum PEMFC parameters, namely, porosity and polytetrafluoroethylene (PTFE content, in the gas diffusion layer (GDL. A 3D model was developed to analyze the properties and effects of GDL. Simulation results showed that the increase in GDL porosity significantly improved the performance of PEMFC in generating electrical power. However, the performance of PEMFC decreased with increasing PTFE content in GDL. Thus, the PTFE content in the GDL must be optimized and the optimum PTFE content should be 5 wt%. The model developed in this simulation showed good capability in simulating the PEMFC parameters to assist the development process of PEMFC design.

  20. Benthic dinoflagellate blooms in tropical intertidal rock pools: Elucidation of photoprotection mechanisms

    Digital Repository Service at National Institute of Oceanography (India)

    Patil, J.S.; Rodrigues, R.V.; Paul, P.; Sathish, K.; Rafi, M.; Anil, A.C.

    accumulation of photoprotective pigments in HT-RPs (due to prolong exposure to solar radiation) could be the reason for the differences. The presence of reduced de-epoxidation state and the mid-day depression in Fv/Fm coupled with elevated ?PSII confirmed...

  1. Sex-related differences in lipid peroxidation and photoprotection in Pistacia lentiscus.

    Science.gov (United States)

    Juvany, Marta; Müller, Maren; Pintó-Marijuan, Marta; Munné-Bosch, Sergi

    2014-03-01

    Sex-related differences in the response of dioecious plants to abiotic stress have been poorly studied to date. This work explored to what extent sex may affect plant stress responses in Pistacia lentiscus L. (Anacardiaceae), a tree well adapted to Mediterranean climatic conditions. It was hypothesized that a greater reproductive effort in females may increase oxidative stress in leaves, particularly when plants are exposed to abiotic stress. Measurements of oxidative stress markers throughout the year revealed increased lipid peroxidation in females, but only during the winter. Enhanced lipid peroxidation in females was associated with reduced photoprotection, as indicated by reduced tocopherol levels and nonphotochemical quenching (NPQ) of chlorophyll fluorescence. Enhanced lipid peroxidation in females was also observed at predawn, which was associated with increased lipoxygenase activity and reduced cytokinin levels. An analysis of the differences between reproductive (R) and nonreproductive (NR) shoots showed an enhanced photoprotective capacity in R shoots compared to NR shoots in females. This capacity was characterized by an increased NPQ and a better antioxidant protection (increased carotenoid and tocopherol levels per unit of chlorophyll) in R compared to NR shoots. It is concluded that (i) females exhibit higher lipid peroxidation in leaves than males, but only during the winter (when sex-related differences in reproductive effort are the highest), (ii) this is associated with a lower photoprotective capacity at midday, as well as enhanced lipoxygenase activity and reduced cytokinin levels at predawn, and (iii) photoprotection capacity is higher in R relative to NR shoots in females.

  2. Effects of propylene, methyl methacrylate and isopropanol poisoning on spatial performance of a proton exchange membrane fuel cell

    Science.gov (United States)

    Reshetenko, Tatyana V.; St-Pierre, Jean

    2018-02-01

    This paper studies the effects of propylene, methyl methacrylate (MMA) and isopropanol (IPA) in air on the spatial performance of proton exchange membrane fuel cells (PEMFCs). The introduction of 100 ppm C3H6 into the oxidant stream resulted in a performance decrease of 130 mV at 1.0 A cm-2, whereas 20 ppm MMA caused a voltage loss of 80 mV. A moderate performance decline of 60 mV was detected in the presence of 5.3ṡ103 ppm IPA in air. Spatial electrochemical impedance spectroscopy (EIS) data showed an increase in charge and mass transfer resistances under exposure to C3H6 and MMA, although IPA did not affect the impedance. The observed PEMFC performances, local current redistributions and EIS data can be explained by the adsorption of contaminants on the Pt surface, their subsequent transformations, and their impacts on the electrochemical surface area and oxygen reduction mechanism. It was assumed that the studied contaminants were oxidized mainly to CO2 via electrochemical and chemical pathways under the operating conditions and at the cathode potential. Self-recovery of PEMFC performance was observed for each contaminant after halting its introduction into the air. Possible contaminant oxidation/reduction mechanisms and their correlations with spatial performance and EIS are presented and discussed.

  3. Performance Assessment in a Heat Exchanger Tube with Opposite/Parallel Wing Twisted Tapes

    Directory of Open Access Journals (Sweden)

    S. Eiamsa-ard

    2015-02-01

    Full Text Available The thermohydraulic performance in a tube containing a modified twisted tape with alternate-axes and wing arrangements is reported. This work aims to investigate the effects of wing arrangements (opposite (O and parallel (P wings at different wing shapes (triangle (Tri, rectangular (Rec, and trapezoidal (Tra wings and on the thermohydraulic performance characteristics. The obtained results show that wing twisted tapes with all wing shape arrangements (O-Tri/O-Rec/O-Tra/P-Tri/P-Rec/P-Tra give superior thermohydraulic performance and heat transfer rate to the typical twisted tape. In addition, the tapes with opposite wing arrangement of O-Tra, O-Rec, and O-Tri give superior thermohydraulic performances to those with parallel wing arrangement of P-Tra, P-Rec, and P-Tri around 2.7%, 3.5%, and 3.2%, respectively.

  4. Transient Performance Behavior of Proton Exchange Membrane Fuel Cell by Configuration of Membrane and Gas Diffusion Layer

    Science.gov (United States)

    Hwang, Sang Soon; Han, Sang Seok; Lee, Pil Hyong; Park, Bong Il

    A single-phase, fully three-dimensional transient numerical simulation was performed to analyze the dynamic response of a proton exchange membrane fuel cell (PEMFC) with single serpentine flow channels. . In addition, the effects of the membrane and gas diffusion layer thickness on current density transient behavior were investigated using numerical simulation. An overshoot of current density is observed for all thicknesses of the membrane and gas diffusion layer at an abrupt change of operating voltage from 0.7 V to 0.5 V. The peak of the overshoot and the elapsed thickness time to reach to the steady state value increase with decreasing membrane thickness. It is thought that the thin membrane facilitates the transport of water and ions through the membrane, resulting in an increase in current density and humidification of the membrane. The elapsed time to reach steady state voltage become shorter and the peak of the overshoot decreases as the thickness of the gas diffusion layer decreases. We suggest that this occurs because a thick gas diffusion layer increases the distance between the current collector (as heat exchanger) and catalyst layer (as heat source), resulting in a low transport rate of heat generated by the electrochemical reaction at the catalyst layer.

  5. Performance of membrane electrode assemblies based on proton exchange membranes prepared by pre-irradiation induced grafting

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jingye; Matsuura, Akio; Kakigi, Tomoyuki; Miura, Takaharu; Oshima, Akihiro; Washio, Masakazu [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)

    2006-10-20

    Proton exchange membranes (PEMs) were prepared by pre-irradiation induced grafting of styrene (S) or styrene/divinylbenzene (S/DVB) into the radiation-crosslinked polytetrafluoroethylene (RX-PTFE) films and then sulfonated. The thicknesses of the obtained PEMs were lower than 20{mu}m and the ion exchange capacity (IEC) values were around 2meqg{sup -1}. The surfaces of the PEMs and carbon electrodes were coated with Nafion{sup (R)} dispersion, and then membrane electrode assembles (MEAs) were prepared by hot-pressing them together. A MEA based on a Nafion{sup (R)} 112 membrane was also prepared under same procedure for comparison. The performances of the MEAs in a single cell were tested under different cell temperatures and humidifications. Electrochemical impedance spectra (EIS) were measured with ac frequencies which ranged from 100kHz to 1Hz at a dc density of 0.5Acm{sup -2}. The obtained impedance curves in Nyquist representation were semicircular. (author)

  6. PHOTOPROTECTION OF SEA-ICE MICROALGAL COMMUNITIES FROM THE EAST ANTARCTIC PACK ICE(1).

    Science.gov (United States)

    Petrou, Katherina; Hill, Ross; Doblin, Martina A; McMinn, Andrew; Johnson, Robert; Wright, Simon W; Ralph, Peter J

    2011-02-01

    All photosynthetic organisms endeavor to balance energy supply with demand. For sea-ice diatoms, as with all marine photoautotrophs, light is the most important factor for determining growth and carbon-fixation rates. Light varies from extremely low to often relatively high irradiances within the sea-ice environment, meaning that sea-ice algae require moderate physiological plasticity that is necessary for rapid light acclimation and photoprotection. This study investigated photoprotective mechanisms employed by bottom Antarctic sea-ice algae in response to relatively high irradiances to understand how they acclimate to the environmental conditions presented during early spring, as the light climate begins to intensify and snow and sea-ice thinning commences. The sea-ice microalgae displayed high photosynthetic plasticity to increased irradiance, with a rapid decline in photochemical efficiency that was completely reversible when placed under low light. Similarly, the photoprotective xanthophyll pigment diatoxanthin (Dt) was immediately activated but reversed during recovery under low light. The xanthophyll inhibitor dithiothreitol (DTT) and state transition inhibitor sodium fluoride (NaF) were used in under-ice in situ incubations and revealed that nonphotochemical quenching (NPQ) via xanthophyll-cycle activation was the preferred method for light acclimation and photoprotection by bottom sea-ice algae. This study showed that bottom sea-ice algae from the east Antarctic possess a high level of plasticity in their light-acclimation capabilities and identified the xanthophyll cycle as a critical mechanism in photoprotection and the preferred means by which sea-ice diatoms regulate energy flow to PSII. © 2011 Phycological Society of America.

  7. How do leader-member exchange quality and differentiation affect performance in teams? An integrated multilevel dual process model.

    Science.gov (United States)

    Li, Alex Ning; Liao, Hui

    2014-09-01

    Integrating leader-member exchange (LMX) research with role engagement theory (Kahn, 1990) and role system theory (Katz & Kahn, 1978), we propose a multilevel, dual process model to understand the mechanisms through which LMX quality at the individual level and LMX differentiation at the team level simultaneously affect individual and team performance. With regard to LMX differentiation, we introduce a new configural approach focusing on the pattern of LMX differentiation to complement the traditional approach focusing on the degree of LMX differentiation. Results based on multiphase, multisource data from 375 employees of 82 teams revealed that, at the individual level, LMX quality positively contributed to customer-rated employee performance through enhancing employee role engagement. At the team level, LMX differentiation exerted negative influence on teams' financial performance through disrupting team coordination. In particular, teams with the bimodal form of LMX configuration (i.e., teams that split into 2 LMX-based subgroups with comparable size) suffered most in team performance because they experienced greatest difficulty in coordinating members' activities. Furthermore, LMX differentiation strengthened the relationship between LMX quality and role engagement, and team coordination strengthened the relationship between role engagement and employee performance. Theoretical and practical implications of the findings are discussed. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  8. INVESTIGATION OF THERMAL PERFORMANCE OF AIR TO WATER HEAT EXCHANGER USING NANO-FLUIDS

    Directory of Open Access Journals (Sweden)

    Nawaf Hazim Saeid

    2011-12-01

    Full Text Available 0 0 1 291 1661 International Islamic University 13 3 1949 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Times New Roman";} In the present study the three-dimensional numerical simulation is selected as a tool to investigate the effectiveness of a cross flow heat exchanger. Water is selected to be mixed with nano-particles and flow inside a circular pipe while a pure air is flowing across it. Numerical simulations is carried out under laminar flow for both water and air sides. The thickness of the pipe is neglected in the present preliminary study. From the physics of the problem, the governing parameters can be determined as: the Reynolds, the type and the volume fraction of the nono-fluid. The effect of these governing parameters is studied and the results are presented. The results show significant enhancement of heat transfer with introduction of nano-particles, such as titanium-oxide (TiO2 nano-powder, compared to the pure base fluid. The accuracy of the results presented in the present study depends on the accuracy of the effective properties of the nano-fluids, which are taken from the open literature. ABSTRAK: Dalam kajian ini, simulasi tiga dimensi berangka digunakan untuk mengkaji keberkesanan penukar haba aliran silang.  Air dipilih untuk dicampurkan dengan zarah bersaiz nano dan dialirkan di dalam paip berbentuk bulat, sementara udara tulen mengalir melaluinya.  Simulasi berangka dijalankan di bawah aliran lamina untuk kedua-dua belah air dan udara. Ketebalan paip diabaikan di dalam kajian permulaan ini.  Dari sudut permasalahan fizik, parameter pengawal imbang boleh ditentukan sebagai

  9. Numerical simulation and experimental validation of internal heat exchanger influence on CO{sub 2} trans-critical cycle performance

    Energy Technology Data Exchange (ETDEWEB)

    Rigola, Joaquim; Ablanque, Nicolas; Perez-Segarra, Carlos D.; Oliva, Assensi [Centre Tecnologic de Transferencia de Calor (CTTC), Universitat Politecnica de Catalunya (UPC), ETSEIAT, C. Colom 11, 08222 Terrassa (Barcelona) (Spain)

    2010-06-15

    The present paper is a numerical and experimental comparative study of the whole vapour compression refrigerating cycle in general, and reciprocating compressors in particular, with the aim of showing the possibilities that CO{sub 2} offers for commercial refrigeration, considering a single-stage trans-critical cycle using semi-hermetic reciprocating compressors under small cooling capacity systems. The present work is focussed on the influence of using an internal heat exchanger (IHX) in order to improve the cycle performance under real working conditions. In order to validate the numerical results, an experimental unit specially designed and built to analyze trans-critical refrigerating equipments considering IHX has been built. Both numerical results and experimental data show reasonable good agreement, while the comparative global values conclude the improvement of cooling capacity and COP when IHX is considered in the CO{sub 2} trans-critical cycle. (author)

  10. Effects of proton exchange membrane on the performance and microbial community composition of air-cathode microbial fuel cells.

    Science.gov (United States)

    Lee, Yun-Yeong; Kim, Tae Gwan; Cho, Kyung-Suk

    2015-10-10

    This study investigated the effects of proton exchange membranes (PEMs) on performance and microbial community of air-cathode microbial fuel cells (MFCs). Air-cathode MFCs with reactor volume of 1L were constructed in duplicate with or without PEM (designated as ACM-MFC and AC-MFC, respectively) and fed with a mixture of glucose and acetate (1:1, w:w). The maximum power density and coulombic efficiency did not differ between MFCs in the absence or presence of a PEM. However, PEM use adversely affected maximum voltage production and the rate of organic compound removal (p0.9 and pelectricity generation in MFC systems. Taken together, these findings demonstrate that MFC systems without PEM are more efficient with respect to power production and COD removal as well as exoelectrogen growth. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. A thermal design method for the performance optimization of multi-stream plate-fin heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhe; Li, Yanzhong [Xi’an Jiaotong University, Xi’an (China); Sunden, Bengt [Lund University, Lund (Sweden); Han, Fenghui [Dalian Maritime University, Dalian (China)

    2017-06-15

    An optimization design method based on field synergy principle is developed for Multi-stream plate-fin heat exchangers (MPHEs) with a segmented differential model. The heat exchanger is divided into a number of sub-exchangers along the main stream, and each sub-exchanger consists of N passages along the height of the exchanger. Compared with the traditional heat exchanger design, this method allows temperature and pressure fields to be obtained via coupling calculation with consideration of variable physical properties and the axial heat loss of the heat exchanger. Finally, the heat exchanger is optimally designed using a temperature-difference uniformity optimization factor based on field synergy principle. This design model can provide an accurate temperature field and pressure field, because the stream properties are determined by the mean temperature and pressure of each local sub-exchanger. Optimum results indicate that the temperature distribution on the cross section of the heat exchanger is relatively uniform and that the temperature difference of heat transfer for each stream is always a small value. These characteristics prove the feasibility and effectiveness of this design model. In this paper, a case of five stream plate-fin heat exchangers for an ethylene plant is designed under a practical cold box operating condition with the proposed model, the structure and heat transfer of which are optimally determined. The design model and optimization method proposed in this work can provide theoretical and technical support to the optimization design of MPHEs.

  12. Sweating with Peer Gynt. Performative exchange as a way of accessing scenographic action

    Directory of Open Access Journals (Sweden)

    Astrid von Rosen

    2015-02-01

    Full Text Available The present article addresses the rather complex notion of scenography in relation to historical research. Two performances of Henrik Ibsens’s Peer Gynt are presented as case studies with the aim of stimulating scenographic analyses of historical material. This approach does not dismiss the importance of the dramatic text, or the actors, or the various contexts in which the performances take place. On the contrary, I strongly believe that one always has to account for the multifarious complexity of a theatrical event. However, my research is guided by an interest in exploring ways of accessing long-past practices, forms and events, rather than relying on the assumption that one recovers something stable and fixed. What I claim is very simple: much more reliable knowledge can be produced by exploring, and working with traces from past events and theatrical processes. This approach can be associated with a current trend in theatre studies, in which “historical research has once more come to the fore” (Tessing Schneider & Skjoldager-Nielsen, 2011, 5 as well as an ethic of “being-with” the objects of investigation found in artistic research (e.g. Hannula 2008. On a general level, my approach can be associated with the affective turn in the humanities. Acknowledging corporeality, materiality and sensuousness, this turn also notices the importance of social aspects, transformation and critical development (Diprose, 2002; Meskimmon, 2011.   This study is mainly concerned with the question of how we can theorize, and play with the challenging difference between a performance that one has actually experienced, intellectually as well as physically, and a performance that is accessible only through traces and fragments. I raise this question both as an art history scholar and as a former professional classical and contemporary dancer. This means that I make use of my own experiences from the theatre – an approach that does not detract from the

  13. Impact of Strategic Initiatives in Management Accounting on Corporate Financial Performance: Evidence from Amman Stock Exchange

    OpenAIRE

    Husam Aldeen Al-Khadash; Mete Feridun

    2006-01-01

    This article aims at investigating the link between the practice of Activity Based Costing (ABC), Just-in-Time (JIT), and Total Quality Management (TQM) as strategic initiatives and the improvement in corporate financial performance of 56 industrial shareholding companies in Jordan. Ordinary Least Squares Regression analysis is used to test the association between the awareness level of the importance of using the initiatives and the level of adopting these initiatives. It is also used to ide...

  14. Advance chromatin extraction enhances performance and productivity of cation exchange chromatography-based capture of Immunoglobulin G monoclonal antibodies.

    Science.gov (United States)

    Nian, Rui; Gagnon, Pete

    2016-07-01

    The impact of host cell-derived chromatin was investigated on the performance and productivity of cation exchange chromatography as a method for capture-purification of an IgG monoclonal antibody. Cell culture supernatant was prepared for loading by titration to pH 6.0, dilution with water to a conductivity of 4mS/cm, then microfiltration to remove solids. DNA content was reduced 99% to 30ppm, histone host cell protein content by 76% to 6300ppm, non-histone host cell protein content by 15% to 321,000ppm, and aggregates from 33% to 15%. IgG recovery was 83%. An alternative preparation was performed, adding octanoic acid, allantoin, and electropositive particles to the harvest at pH 5.3, then removing solids. DNA content was reduced toaggregates were reduced to 2.4%. IgG recovery was 95%. This treatment increased dynamic capacity (DBC) of cation exchange capture to 173g/L and enabled the column to reduce non-histone host proteins to 671ppm. Step recovery was 99%. A single multimodal polishing step further reduced them to 15ppm and aggregates to <0.1%. Overall process recovery was 89%. Productivity at feed stream IgG concentrations of 5-10g/L was roughly double the productivity of a same-size protein A column with a DBC of 55g/L. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

  15. Study of operating conditions and cell design on the performance of alkaline anion exchange membrane based direct methanol fuel cells

    Science.gov (United States)

    Prakash, G. K. Surya; Krause, Frederick C.; Viva, Federico A.; Narayanan, S. R.; Olah, George A.

    2011-10-01

    Direct methanol fuel cells using an alkaline anion exchange membrane (AAEM) were prepared, studied, and optimized. The effects of fuel composition and electrode materials were investigated. Membrane electrode assemblies fabricated with Tokuyama® AAEM and commercial noble metal catalysts achieved peak power densities between 25 and 168 mW cm-2 depending on the operating temperature, fuel composition, and electrode materials used. Good electrode wettability at the anode was found to be very important for achieving high power densities. The performance of the best AAEM cells was comparable to Nafion®-based cells under similar conditions. Factors limiting the performance of AAEM MEAs were found to be different from those of Nafion® MEAs. Improved electrode kinetics for methanol oxidation in alkaline electrolyte at Pt-Ru are apparent at low current densities. At high current densities, rapid CO2 production converts the hydroxide anions, necessary for methanol oxidation, to bicarbonate and carbonate: consequently, the membrane and interfacial conductivity are drastically reduced. These phenomena necessitate the use of aqueous potassium hydroxide and wettable electrode materials for efficient hydroxide supply to the anode. However, aqueous hydroxide is not needed at the cathode. Compared to AAEM-based fuel cells, methanol fuel cells based on proton-conducting Nafion® retain better performance at high current densities by providing the benefit of carbon dioxide rejection.

  16. The effect of protein A cycle number on the performance and lifetime of an anion exchange polishing step.

    Science.gov (United States)

    Iskra, Timothy; Bolton, Glen R; Coffman, Jonathan L; Godavarti, Ranga

    2013-04-01

    Most mAb platform purification processes consist of an affinity capture step followed by one or two polishing steps. An understanding of the performance linkages between the unit operations can lead to robust manufacturing processes. In this study, a weak-partitioning anion-exchange chromatography polishing step used in a mAb purification process was characterized through high-throughput screening (HTS) experiments, small-scale experiments including a cycling study performed on qualified scale-down models, and large-scale manufacturing runs. When material from a Protein A column that had been cycled Protein A resin increased, the capacity of the subsequent AEX step increased. Different control strategies were considered for preventing impurity breakthrough and improving AEX resin lifetimes. Depth filtration of the Protein A peak pool significantly improved the AEX resin capacity, robustness, and lifetime. Further, the turbidity of the Protein A pool has the potential for use as an in-process control parameter for monitoring the performance of the AEX step. Copyright © 2012 Wiley Periodicals, Inc.

  17. Analytical Investigation and Improvement of Performance of a Proton Exchange Membrane (Pem) Fuel Cell in Mobile Applications

    Science.gov (United States)

    Khazaee, I.

    2015-05-01

    In this study, the performance of a proton exchange membrane fuel cell in mobile applications is investigated analytically. At present the main use and advantages of fuel cells impact particularly strongly on mobile applications such as vehicles, mobile computers and mobile telephones. Some external parameters such as the cell temperature (Tcell ) , operating pressure of gases (P) and air stoichiometry (λair ) affect the performance and voltage losses in the PEM fuel cell. Because of the existence of many theoretical, empirical and semi-empirical models of the PEM fuel cell, it is necessary to compare the accuracy of these models. But theoretical models that are obtained from thermodynamic and electrochemical approach, are very exact but complex, so it would be easier to use the empirical and smi-empirical models in order to forecast the fuel cell system performance in many applications such as mobile applications. The main purpose of this study is to obtain the semi-empirical relation of a PEM fuel cell with the least voltage losses. Also, the results are compared with the existing experimental results in the literature and a good agreement is seen.

  18. An analysis of strategic performance measures of companies listed on the JSE securities exchange South Africa

    Directory of Open Access Journals (Sweden)

    JHvH de Wet

    2014-07-01

    Full Text Available This study highlights the importance of economic profits (EVA and their long-term effects on shareholder value (MVA. South African companies listed on the JSE were analysed and it is evident that the relative measure of internal performance (spreads can be used to rank companies in terms of value creation. Individual companies and sectors were also placed on a financial strategy matrix, which evaluated companies according to spreads and cash management. The sales growth less the SGR percentage, was used to indicate cash management. Statistical tests (regression analysis were done on the data to test the validity of the financial strategy matrix model. The results showed that there is a positive relationship between spreads and shareholder value, but sales growth less the sustainable growth rate does not contribute significantly to shareholder value.

  19. Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells

    Directory of Open Access Journals (Sweden)

    Henry Fonda Aritonang

    2017-05-01

    Full Text Available Highly dispersed platinum (Pt nanoparticles / multiwalled carbon nanotubes (MWCNTs on bacterial cellulose (BC as anode catalysts for proton exchange membrane fuel cells (PEMFC were prepared with various precursors and their electro-catalytic activities towards hydrogen oxidation at 70 oC under non-humidified conditions. The composite was prepared by deposition of Pt nanoparticles and MWCNTs on BC gel by impregnation method using a water solution of metal precursors and MWCNTs followed by reducing reaction using a hydrogen gas. The composite was characterized by using TEM (transmission electron microscopy, EDS (energy dispersive spectroscopy, and XRD (X-ray diffractometry techniques. TEM images and XRD patterns both lead to the observation of spherical metallic Pt nanoparticles with mean diameter of 3-11 nm well impregnated into the BC fibrils. Preliminary tests on a single cell indicate that renewable BC is a good prospect to be explored as a membrane in fuel cell field. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 26th February 2017; Accepted: 27th February 2017 How to Cite: Aritonang, H.F., Kamu, V.S., Ciptati, C., Onggo, D., Radiman, C.L. (2017. Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 287-292 (doi:10.9767/bcrec.12.2.803.287-292 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.803.287-292

  20. Photoprotection of evergreen and drought-deciduous tree leaves to overcome the dry season in monsoonal tropical dry forests in Thailand.

    Science.gov (United States)

    Ishida, Atsushi; Yamazaki, Jun-Ya; Harayama, Hisanori; Yazaki, Kenichi; Ladpala, Phanumard; Nakano, Takashi; Adachi, Minaco; Yoshimura, Kenichi; Panuthai, Samreong; Staporn, Duriya; Maeda, Takahisa; Maruta, Emiko; Diloksumpun, Sapit; Puangchit, Ladawan

    2014-01-01

    In tropical dry forests, uppermost-canopy leaves of evergreen trees possess the ability to use water more conservatively compared with drought-deciduous trees, which may result from significant differences in the photoprotective mechanisms between functional types. We examined the seasonal variations in leaf gas exchange, chlorophyll fluorescence and the amounts of photosynthetic pigments within lamina of the uppermost-canopy leaves of three drought-deciduous trees (Vitex peduncularis Wall., Xylia xylocarpa (Roxb.) W. Theob., Shorea siamensis Miq.), a semi-deciduous tree (Irvingia malayana Miq.) and two evergreen trees (Hopea ferrea Lanessan and Syzygium cumini (L.) Skeels) in Thailand. Area-based maximum carbon assimilation rates (Amax) decreased during the dry season, except in S. siamensis. The electron transport rate (ETR) remained unchanged in deciduous trees, but decreased during the dry season in evergreen and semi-deciduous trees. In the principal component analysis, the first axis (Axis 1) accounted for 44.3% of the total variation and distinguished deciduous from evergreen trees. Along Axis 1, evergreen trees were characterized by a high Stern-Volmer non-photochemical quenching coefficient (NPQ), high xanthophyll cycle pigments/chlorophyll and a high de-epoxidation state of the xanthophyll cycle, whereas the deciduous trees were characterized by a high ETR, a high quantum yield of PSII (ΦPSII = (Fm(') -F)/Fm(')) and a high mass-based Amax under high-light conditions. These findings indicate that drought-deciduous trees showing less conservative water use tend to dissipate a large proportion of electron flow through photosynthesis or alternative pathways. In contrast, the evergreens showed more conservative water use, reduced Amax and ETR and enhanced NPQ and xanthophyll cycle pigments/chlorophyll during the dry season, indicating that down-regulated photosynthesis with enhanced thermal dissipation of excess light energy played an important role in

  1. Easily exchangeable x-ray mirrors and hybrid monochromator modules a study of their performance

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Fan. [Philips Analytical, Asia Pacific, Toa Payoh, (Singapore); Kogan, V. [Philips Analytical, EA Almelo, (Netherlands); Saito, K. [Philips Analytical, Tokyo, (Japan)

    1999-12-01

    Full text: PreFix prealigned optical mounts allowing rapid and easily changeover will be presented. The benefits of laterally graded multilayer X-Ray mirrors coupled with these Prefix mounts - conversion of divergent beam to parallel beam, increase of intensity by a factor of 3-7, monochromation to {alpha}1 and {alpha}2 and a dynamic range of 10 {sup 4-5} CpS will be demonstrated in areas such as Thin Film and Powder analysis. Data will be shown on a diffraction profile of thin film (Cr/SiO{sub 2}) with and without a mirror and Si powder with and without a mirror. Further enhancement will be demonstrated by combining a channel cut monochromator-collimator with an X-Ray mirror to produce a high intensity, parallel, pure Cu K{alpha}1 beam with a high intensity of up to 4.5 x 10{sup 8} cps and a divergence down to 0.01 deg. The applicability to various ranging from High Resolution to thin film/reflectivity to Rietveld structural refinement and to phase analysis will be shown. The Rocking curve of HEMT 10nm InGaAs on InP will be presented using various `standard` optics and hybrid optics, also Si powder and a Rietveld refinement of CuS0{sub 4}.5H{sub 2}0 and Aspirin. A comparison of the benefits and application of X-Ray Mirrors and Hybrid Mirror/Monochromators will be given. The data presented will show that by using X-Ray Mirrors and Hybrid modules the performance of standard `Laboratory` Diffractometers can be greatly enhanced to a level previously unachievable with great practical benefits. Copyright (1999) Australian X-ray Analytical Association Inc.

  2. The Effect of Pressure and Organic Constituents on the Cesium Ion Exchange Performance of IONSIV IE-911

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F.F.

    2000-07-18

    This study examined cesium ({sup 137}Cs) ion exchange of crystalline silicotitanate (CST) in simulated waste solution. In particular, the study focused on the effect of CST pretreatment on the kinetics and extent of cesium adsorption. The test used IONSIV{reg_sign}IE-911 (UOP LLC, Molecular Sieves Division, Des Plaines, IL), the engineered form of CST. Pretreatment steps examined include: soaking CST in 2M NaOH solution for three days, exposing CST to 50% relative humidity for one week, flowing organic-containing (saturated) salt solution through a CST packed bed (at 5 cm/min. superficial velocity), or drying CST in air at 100 C for three days. Some tests occurred under 50 and 25 psig of argon. The following conclusions summarize the results. Pretreatment of IE-911 in organic-containing (e.g., tri-n-butyl phosphate, dibutylphosphate, butanol, paraffin and Dow Corning H-10 defoamer) simulated waste or simulated waste yielded a 83% slower rate of cesium adsorption and 56% lower cesium capacity after one week. Pretreatment of IE-911 in 2M caustic solution for 48 hours yielded a slower approach to equilibrium cesium distribution in batch contact tests--7.7 mL/(g*h) during the first 48 hours and 2.4 ml/(g*h) thereafter. Carboxylates and adsorbed carbonates inside the pores likely affect the cesium transport by either increasing the path-length or reducing mass transfer rate. Heating IE-911 as received from the vendor at 100 C for 24 hours significantly degraded its cesium removal performance by a 40.7% reduction in capacity and 43% reduction in sorption rate over one week of testing. Testing determined nearly identical distribution coefficients K{sub d} between lot {number_sign} 9990-9681-0004 and 9990-9881-0005 (i.e., difference of only 5.6%). Tests measuring water insertion rates into IE-911 show that hydration of the IE-911 does not appear to limit the rate of cesium sorption. Increasing the atmospheric pressure from 0 to 50 psig had no effect on cesium sorption

  3. Influence of various carbon nano-forms as supports for Pt catalyst on proton exchange membrane fuel cell performance

    Science.gov (United States)

    Bharti, Abha; Cheruvally, Gouri

    2017-08-01

    In this study, we discuss the influence of various carbon supports for Pt on proton exchange membrane (PEM) fuel cell performance. Here, Pt supported on various carbon nano-forms [Pt/carbon black (Pt/CB), Pt/single-walled carbon nanotubes (Pt/SWCNT), Pt/multi-walled carbon nanotubes (Pt/MWCNT) and Pt/graphene (Pt/G)] are synthesized by a facile, single step, microwave-assisted, modified chemical reduction route. Their physical, chemical and electrochemical characteristics pertaining to oxygen reduction reaction (ORR) catalytic activity and stability in PEM fuel cell are studied in detail by various techniques and compared. The study shows that the different carbon supports does not significantly affect the Pt particle size during synthesis, but leads to different amount of defective sites in the carbon framework which influence both the availability of active metal nano-catalysts and metal-support interaction. In-situ electrochemical investigations reveal that the different carbon supports influence both ORR catalytic activity and stability of the catalyst. This is further corroborated by the demonstration of varying polarization characteristics on PEM fuel cell performance by different carbon supported Pt catalysts. This study reveals MWCNT as the most suitable carbon support for Pt catalyst, exhibiting high activity and stability for ORR in PEM fuel cell.

  4. Comparative Performance of Thermoacoustic Heat Exchangers with Different Pore Geometries in Oscillatory Flow. Implementation of Experimental Techniques

    Directory of Open Access Journals (Sweden)

    Antonio Piccolo

    2017-08-01

    Full Text Available Heat exchangers (HXs constitute key components of thermoacoustic devices and play an important role in determining the overall engine performance. In oscillatory flow conditions, however, standard heat transfer correlations for steady flows cannot be directly applied to thermoacoustic HXs, for which reliable and univocal design criteria are still lacking. This work is concerned with the initial stage of a research aimed at studying the thermal performance of thermoacoustic HXs. The paper reports a detailed discussion of the design and fabrication of the experimental set-up, measurement methodology and test-HXs characterized by two different pore geometries, namely a circular pore geometry and a rectangular (i.e., straight fins pore geometry. The test rig is constituted by a standing wave engine where the test HXs play the role of ambient HXs. The experiment is conceived to allow the variation of a range of testing conditions such as drive ratio, operation frequency, acoustic particle velocity, etc. The procedure for estimating the gas side heat transfer coefficient for the two involved geometries is described. Some preliminary experimental results concerning the HX with straight fins are also shown. The present research could help in achieving a deeper understanding of the heat transfer processes affecting HXs under oscillating flow regime and in developing design optimization procedures.

  5. Experimental performance and parametric analysis of heat pipe heat exchanger for air conditioning application integrated with evaporative cooling

    Science.gov (United States)

    Jadhav, Tushar S.; Lele, Mandar M.

    2017-11-01

    The experimental performance of different heat pipe heat exchanger (HPHX) configurations using distilled water as the working fluid is reported in the present study. The three HPHX configurations in the present investigation include HPHX with single wick structure (HPHX 1), HPHX with composite wick structure (HPHX 2) and hybrid HPHX (HPHX 3) which is the combination of HPHX 1 and HPHX 2. The parameters considered for the parametric analysis of HPHX in all the three configurations are outdoor air dry bulb temperature entering the evaporator section of HPHX (OADBT), return air dry bulb temperature entering the condenser section of HPHX (RADBT), outdoor air velocity (Ve) and return air velocity (Vc). The OADBT is varied between 40 and 24 °C and the outdoor & return air velocities between 0.6 and 2.4 m/s. The parametric analysis of HPHX without evaporative cooling is studied for RADBT = 24 °C whereas RADBT is maintained at 20 °C for the parametric analysis of HPHX integrated with evaporative cooling. In comparison with HPHX without evaporative cooling, the performance of HPHX with evaporative cooling is enhanced by 17% for single wick structure (HPHX 1), 47% for composite wick structure (HPHX 2) and 59% for hybrid HPHX (HPHX 3) for OADBT = 40 °C and at Ve = Vc of 0.6 m/s. The results of the experimental analysis highlights the benefits of HPHX integrated with evaporative cooling for achieving significant energy savings in air conditioning application.

  6. Performance comparison between high temperature and traditional proton exchange membrane fuel cell stacks using electrochemical impedance spectroscopy

    Science.gov (United States)

    Zhu, Ying; Zhu, Wenhua H.; Tatarchuk, Bruce J.

    2014-06-01

    A temperature above 100 °C is always desired for proton exchange membrane (PEM) fuel cell operation. It not only improves kinetic and mass transport processes, but also facilitates thermal and water management in fuel cell systems. Increased carbon monoxide (CO) tolerance at higher operating temperature also simplifies the pretreatment of fuel supplement. The novel phosphoric acid (PA) doped polybenzimidazole (PBI) membranes achieve PEM fuel cell operations above 100 °C. The performance of a commercial high temperature (HT) PEM fuel cell stack module is studied by measuring its impedance under various current loads when the operating temperature is set at 160 °C. The contributions of kinetic and mass transport processes to stack impedance are analyzed qualitatively and quantitatively by equivalent circuit (EC) simulation. The performance of a traditional PEM fuel cell stack module operated is also studied by impedance measurement and EC simulation. The operating temperature is self-stabilized between 40 °C and 65 °C. An enhancement of the HT-PEM fuel cell stack in polarization impedance is evaluated by comparing to the traditional PEM fuel cell stack. The impedance study on two commercial fuel cell stacks reveals the real situation of current fuel cell development.

  7. Analysis of alkaline exchange membrane fuel cells performance at different operating conditions using DC and AC methods

    Science.gov (United States)

    Reshetenko, Tatyana; Odgaard, Madeleine; Schlueter, Debbie; Serov, Alexey

    2018-01-01

    Membrane electrode assemblies (MEAs) for anion exchange membrane fuel cells (AEMFCs) were manufactured from commercial materials: Pt/C catalyst, A201 AEM and AS4 ionomer by using an industrial mass-production digital printing method. The MEA designs selected are close to those recommended by US Department of Energy, including low loading of platinum on the cathode side (0.2 mg cm-2). Polarization curves and electrochemical impedance spectroscopy (EIS) were applied for MEA evaluation in fuel cell conditions with variation of gas humidification and oxygen partial pressure (air vs oxygen). The typical impedance curves recorded at H2/O2 gas configuration consist of high- and medium-frequency arcs responsible for hydrogen oxidation and oxygen reduction, respectively. Operation with air as a cathode feed gas resulted in a decrease in AEMFC performance due to possible CO2 poisoning and mass transfer losses. At the same time, EIS demonstrated formation of a low frequency loop due to diffusion limitations. Despite the low loading of platinum on the cathode (0.2 mg cm-2), a peak power density of ∼330 mW cm-2 was achieved (at 50/50% of RH on anode and cathode), which is substantially higher performance than for AEMFC MEAs tested at similar conditions.

  8. Leader-member exchange and member performance: a new look at individual-level negative feedback-seeking behavior and team-level empowerment climate.

    Science.gov (United States)

    Chen, Ziguang; Lam, Wing; Zhong, Jian An

    2007-01-01

    From a basis in social exchange theory, the authors investigated whether, and how, negative feedback-seeking behavior and a team empowerment climate affect the relationship between leader-member exchange (LMX) and member performance. Results showed that subordinates' negative feedback-seeking behavior mediated the relationship between LMX and both objective and subjective in-role performance. In addition, the level of a team's empowerment climate was positively related to subordinates' own sense of empowerment, which in turn negatively moderated the effects of LMX on negative feedback-seeking behavior. 2007 APA, all rights reserved

  9. Hydrogen bond dynamics governs the effective photoprotection mechanism of plant phenolic sunscreens.

    Science.gov (United States)

    Liu, Fang; Du, Likai; Lan, Zhenggang; Gao, Jun

    2017-02-15

    Sinapic acid derivatives are important sunscreen species in natural plants, which could provide protection from solar UV radiation. Using a combination of ultrafast excited state dynamics, together with classical molecular dynamics studies, we demonstrate that there is direct coupling of hydrogen bond motion with excited state photoprotection dynamics as part of the basic mechanism in solution. Beyond the intra-molecular degree of freedom, the inter-molecular motions on all timescales are potentially important for the photochemical or photophysical events, ranging from the ultrafast hydrogen bond motion to solvent rearrangements. This provides not only an enhanced understanding of the anomalous experimental spectroscopic results, but also the key idea in the development of sunscreen agents with improved photo-chemical properties. We suggest that the hydrogen bond dynamics coupled excited state photoprotection mechanism may also be possible in a broad range of bio-related molecules in the condensed phase.

  10. Light harvesting, light adaptation and photoprotection in aquatic photosynthesis studies by time-resolved fluorescence spectroscopy

    OpenAIRE

    Chukhutsina, V.

    2015-01-01

    Summary Aquatic photosynthetic organisms unavoidably experience light fluctuations that vary in amplitude, duration and origin, compromising their photosynthetic efficiency. Weather conditions and underwater flow cause continuous changes in irradiance to which the organisms have to adapt. Many light-adaptation strategies of photosynthetic organisms, such as light acclimation, photoprotection and state transitions are still not well understood. In this thesis, time-resolved fluorescence s...

  11. Photochemistry of Eumelanin Precursors Role of Excited State Proton Transfer for UV Photoprotection

    OpenAIRE

    Corani, Alice

    2015-01-01

    Melanin is an epidermal pigment commonly known to give darker skin coloration under sun exposure. It is also present in the hair, eyes, inner ear and brain. The first function of epidermis melanin is believed to be photoprotective against harmful ultraviolet (UV) light, but the recent increase of skin cancer correlated to an increase of sun exposure questions the properties of melanin. Its presence in different body parts suggests that its function is not solely protective against...

  12. Photoprotection as a Trait for Rice Yield Improvement: Status and Prospects

    OpenAIRE

    Murchie, Erik H.; Ali, Asgar; Herman, Tiara

    2015-01-01

    Solar radiation is essential for photosynthesis and global crop productivity but it is also variable in space and time, frequently being limiting or in excess of plant requirements depending on season, environment and microclimate. Photoprotective mechanisms at the chloroplast level help to avoid oxidative stress and photoinhibition, which is a light-induced reduction in photosynthetic quantum efficiency often caused by damage to photosystem II. There is convincing evidence that photoinhibiti...

  13. In vitro antioxidant and in vivo photoprotective effects of an association of bioflavonoids with liposoluble vitamins.

    Science.gov (United States)

    Maia Campos, Patrícia M B G; Gianeti, Mirela D; Kanashiro, Alexandre; Lucisano-Valim, Yara M; Gaspar, Lorena R

    2006-01-01

    A new tendency in cosmetic formulations is the association of botanical extracts and vitamins to improve skin conditions by synergic effects. The objective of this study was to determine the antioxidant activity of associated bioflavonoids, retinyl palmitate (RP), tocopheryl acetate (TA) and ascorbyl tetraisopalmitate (ATIP), as well as their photoprotective effects in preventing increased erythema, transepidermal water loss (TEWL) and sunburn cell formation in hairless mouse skin. The antioxidant activity of solutions containing the association or each substance separately was evaluated in vitro by a chemiluminescence assay. The photoprotective effect was evaluated by means of in vivo tests. Dorsal skin of hairless mice was treated daily by topical applications for 5 days with formulations containing or not containing (vehicle) the flavonoid-vitamins association (5%). The skin was irradiated (UVA/B) 15 minutes after the last application. The results showed that bioflavonoids had in vitro antioxidant properties and also that when they were associated with vitamins their antioxidant activity was more pronounced. On the other hand, erythema and UV damage to the permeability barrier function (TEWL) was not significantly reduced by previous treatment with the flavonoid-vitamin-association formulations, when compared to the irradiated vehicle-treated area. However, the treatment protected the skin from UV damage because it reduced the number of sunburn cells, when compared to the vehicle-treated area. Finally, the association of vitamins and bioflavonoids added to a dermocosmetic formulation showed a relevant biological activity in terms of photoprotection, because the association of bioflavonoids and vitamins acted by different mechanisms, such as antioxidation and absorption of UV radiation, which suggests its use in antiaging and photoprotective products.

  14. Regulation and function of xanthophyll cycle-dependent photoprotection in algae.

    Science.gov (United States)

    Goss, Reimund; Jakob, Torsten

    2010-11-01

    The xanthophyll cycle represents one of the important photoprotection mechanisms in plant cells. In the present review, we summarize current knowledge about the violaxanthin cycle of vascular plants, green and brown algae, and the diadinoxanthin cycle of the algal classes Bacillariophyceae, Xanthophyceae, Haptophyceae, and Dinophyceae. We address the biochemistry of the xanthophyll cycle enzymes with a special focus on protein structure, co-substrate requirements and regulation of enzyme activity. We present recent ideas regarding the structural basis of xanthophyll cycle-dependent photoprotection, including different models for the mechanism of non-photochemical quenching of chlorophyll a fluorescence. In a dedicated chapter, we also describe the unique violaxanthin antheraxanthin cycle of the Prasinophyceae, together with its implication for the mechanism of xanthophyll cycle-dependent heat dissipation. The interaction between the diadinoxanthin cycle and alternative electron flow pathways in the chloroplasts of diatoms is an additional topic of this review, and in the last chapter we cover aspects of the importance of xanthophyll cycle-dependent photoprotection for different algal species in their natural environments.

  15. Synergic Effect of Genistein and Daidzein on UVB-Induced DNA Damage: An Effective Photoprotective Combination

    Directory of Open Access Journals (Sweden)

    Barbara Iovine

    2011-01-01

    Full Text Available The anti-inflammatory effects and antioxidant activities of individual isoflavones are well established although little is known about the photoprotective effect of their combination. The aim of this study was to investigate the photoprotective effects of different concentrations of genistein and daidzein individually or combined. We measured the expression levels of the cyclo-oxygenase-2 (COX-2 and growth arrest and DNA-damage inducible (Gadd45 genes, which are involved in inflammation and DNA repair, respectively, in BJ-5ta human skin fibroblasts irradiated with 60 mJ/cm2 UVB. We also determined the cellular response to UVB-induced DNA damage by Comet assay. We report that genistein and daidzein when administered combined, and at a specific concentration and ratio, exerted a synergistic photoprotective effect that was greater than the effect obtained with each isoflavone alone. The results reported herein suggest that low concentrations of genistein and daidzein combined may be good candidate ingredients for protective agents against UV-induced photodamage.

  16. DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea

    Science.gov (United States)

    Jones, Daniel L.; Baxter, Bonnie K.

    2017-01-01

    Halophilic archaea push the limits of life at several extremes. In particular, they are noted for their biochemical strategies in dealing with osmotic stress, low water activity and cycles of desiccation in their hypersaline environments. Another feature common to their habitats is intense ultraviolet (UV) radiation, which is a challenge that microorganisms must overcome. The consequences of high UV exposure include DNA lesions arising directly from bond rearrangement of adjacent bipyrimidines, or indirectly from oxidative damage, which may ultimately result in mutation and cell death. As such, these microorganisms have evolved a number of strategies to navigate the threat of DNA damage, which we differentiate into two categories: DNA repair and photoprotection. Photoprotection encompasses damage avoidance strategies that serve as a “first line of defense,” and in halophilic archaea include pigmentation by carotenoids, mechanisms of oxidative damage avoidance, polyploidy, and genomic signatures that make DNA less susceptible to photodamage. Photolesions that do arise are addressed by a number of DNA repair mechanisms that halophilic archaea efficiently utilize, which include photoreactivation, nucleotide excision repair, base excision repair, and homologous recombination. This review seeks to place DNA damage, repair, and photoprotection in the context of halophilic archaea and the solar radiation of their hypersaline environments. We also provide new insight into the breadth of strategies and how they may work together to produce remarkable UV-resistance for these microorganisms. PMID:29033920

  17. Responses of foliar antioxidative and photoprotective defence systems of trees to drought: a meta-analysis.

    Science.gov (United States)

    Wujeska, Agnieszka; Bossinger, Gerd; Tausz, Michael

    2013-10-01

    Current climate change predictions hint to more frequent extreme weather events, including extended droughts, making better understanding of the impacts of water stress on trees even more important. At the individual plant level, stomatal closure as a result of water deficit leads to reduced CO2 availability in the leaf, which can lead to photo-oxidative stress. Photorespiration and the Mehler reaction can maintain electron transport rates under low internal CO2, but result in production of reactive oxygen species (ROS). If electron consumption is decreased, upstream photochemical processes can be affected and light energy is absorbed in excess of photochemical requirements. Trees evolved to cope with excess energy and elevated concentration of ROS by activating photoprotective and antioxidative defence systems. The meta-analysis we present here assessed responses of these defence systems reported in 50 studies. We found responses to vary depending on stress intensity, foliage type and habitat, and on whether experiments were done in the field or in controlled environments. In general, drought increased concentrations of antioxidants and photoprotective pigments. However, severe stress caused degradation of antioxidant concentrations and oxidation of antioxidant pools. Evergreen trees seemed to preferentially reinforce membrane-bound protection systems zeaxanthin and tocopherol, whereas deciduous species showed greater responses in water-soluble antioxidants ascorbic acid and glutathione. Trees and shrubs from arid versus humid habitats vary in their antioxidative and photoprotective defence responses. In field experiments, drought had greater effects on some defence compounds than under controlled conditions.

  18. Structural mechanism and photoprotective function of water-soluble chlorophyll-binding protein.

    Science.gov (United States)

    Horigome, Daisuke; Satoh, Hiroyuki; Itoh, Nobue; Mitsunaga, Katsuyoshi; Oonishi, Isao; Nakagawa, Atsushi; Uchida, Akira

    2007-03-02

    A water-soluble chlorophyll-binding protein (WSCP) is the single known instance of a putative chlorophyll (Chl) carrier in green plants. Recently the photoprotective function of WSCP has been demonstrated by EPR measurements; the light-induced singlet-oxygen formation of Chl in the WSCP tetramer is about four times lower than that of unbound Chl. This paper describes the crystal structure of the WSCP-Chl complex purified from leaves of Lepidium virginicum (Virginia pepperweed) to clarify the mechanism of its photoprotective function. The WSCP-Chl complex is a homotetramer comprising four protein chains of 180 amino acids and four Chl molecules. At the center of the complex one hydrophobic cavity is formed in which all of the four Chl molecules are tightly packed and isolated from bulk solvent. With reference to the novel Chl-binding mode, we propose that the photoprotection mechanism may be based on the inhibition of physical contact between the Chl molecules and molecular oxygen.

  19. DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea

    Directory of Open Access Journals (Sweden)

    Daniel L. Jones

    2017-09-01

    Full Text Available Halophilic archaea push the limits of life at several extremes. In particular, they are noted for their biochemical strategies in dealing with osmotic stress, low water activity and cycles of desiccation in their hypersaline environments. Another feature common to their habitats is intense ultraviolet (UV radiation, which is a challenge that microorganisms must overcome. The consequences of high UV exposure include DNA lesions arising directly from bond rearrangement of adjacent bipyrimidines, or indirectly from oxidative damage, which may ultimately result in mutation and cell death. As such, these microorganisms have evolved a number of strategies to navigate the threat of DNA damage, which we differentiate into two categories: DNA repair and photoprotection. Photoprotection encompasses damage avoidance strategies that serve as a “first line of defense,” and in halophilic archaea include pigmentation by carotenoids, mechanisms of oxidative damage avoidance, polyploidy, and genomic signatures that make DNA less susceptible to photodamage. Photolesions that do arise are addressed by a number of DNA repair mechanisms that halophilic archaea efficiently utilize, which include photoreactivation, nucleotide excision repair, base excision repair, and homologous recombination. This review seeks to place DNA damage, repair, and photoprotection in the context of halophilic archaea and the solar radiation of their hypersaline environments. We also provide new insight into the breadth of strategies and how they may work together to produce remarkable UV-resistance for these microorganisms.

  20. Photoprotective Effect of the Plant Collaea argentina against Adverse Effects Induced by Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Leandro Mamone

    2014-01-01

    Full Text Available Photodynamic therapy (PDT is a treatment modality for tumours and other accessible lesions based on the combination of light and a photosensitizer (PS accumulated in the target tissue. The main disadvantage of PDT is PS retention after treatment during long time periods that conduces to cutaneous damage. It is believed that singlet oxygen is responsible for that skin photosensitization. The aim of this work was to evaluate the photoprotective activity of the methanolic extract of the Argentinian plant Collaea argentina against PDT under several treatments and employing different PSs. C. argentina exhibited photoprotective activity against aminolevulinic acid- (ALA- PDT in the LM2 murine adenocarcinoma cell line. The photoprotection was dependant on the extract concentration and the incubation time, being detectable from 40 μg/mL onwards and at least after 3 h exposure of the cells. C. argentina extract protects these mammalian tumor cells against PDT effects, and it interferes with the oxygen singlet production from PSs during PDT treatment. We propose that it will be a promising agent to protect cells against PDT-induced skin sensitivity.

  1. The implications of financial performance on stock exchange indicators of listed companies: empirical evidence for the Romanian capital market

    Directory of Open Access Journals (Sweden)

    Iulia-Oana ȘTEFAN(BELCIC-ȘTEFAN

    2016-08-01

    Full Text Available This paper examines and quantifies the implications of financial indicators of performance on the share return of companies listed on Bucharest Stock Exchange. These implications are even more relevant as the Romanian capital market could benefit from increased visibility with its reclassification as an emerging capital market in the near future. The research is conducted at the level of 33 companies listed on BSE for the time frame 2011-2013, building a multiple linear regression model that quantifies the variation in price to book value depending on the evolution of nine financial indicators of performance out of a total of 38 such possible indicators. Correcting the effects of serial correlation within the model led to its respecification resorting to the generalized differences procedure. The value of the R-squared coefficient of determination for the processed model is 0.543, eight of the nine independent variables being significant at the 1% level. The 0 probability associated to the F-test as well as its value confirm that the regression equation is globally significant. Also, all the assumptions for validating the estimated model are confirmed, both general ones, characteristic to the multiple linear regression procedure, and, in particular, according to the specific set of data under processing. The applied usefulness of the regression model is valued in the next step of the research, that of testing the effectiveness of the Romanian capital market, after which it was found that the influence of financial performance indicators was already incorporated into the market price since the end of the reporting period.

  2. Comparative Analysis of A, B Type and Exchange Traded Funds Performances with Mutual Fund Performance Measures, Regression Analysis and Manova Technique.

    Directory of Open Access Journals (Sweden)

    Mehmet Arslan

    2010-06-01

    Full Text Available The objective of the study is to evaluate risk- reward relationship and relative performances of the 4 different groups of mutual funds. To this end, daily return data of these 12 mutual funds (3 type variable fund; 3 B type variable fund; 3 A type stock fund and 3 A type Exchange traded fund together with daily market index (imkb100 return and daily return of riskless rate for the period from January 2006 to Feb 2010. The 180-day maturity T-Bill has been selected to represent riskless rate. To determine performances of mutual funds; Sharpe ratio, M2 measure, Treynor index, Jensen index, Sortino ratio, T2 ratio, Valuation ratio has been applied and these indicators produced conflicting results in ranking mutual funds. Then timingand selection capability of the fund manager has been determined by applying simple regression and Quadratic regression. Interestingly all funds found to have positive coefficient, indicating positive election capability of managers; but in terms of timing capability only one fund managers showed success. Finally, to determine extent to which mean returns are differs between mutual funds, market index (imkb100 and riskless rate (180 day TBill results of the analysis revealed that mean returns of individual security returns differs at P≤0,01 level. That shows instability in returns and poor ex-ante forecast modeling capability.

  3. Method for the direct determination of available carbohydrates in low-carbohydrate products using high-performance anion exchange chromatography.

    Science.gov (United States)

    Ellingson, David; Potts, Brian; Anderson, Phillip; Burkhardt, Greg; Ellefson, Wayne; Sullivan, Darryl; Jacobs, Wesley; Ragan, Robert

    2010-01-01

    An improved method for direct determination of available carbohydrates in low-level products has been developed and validated for a low-carbohydrate soy infant formula. The method involves modification of an existing direct determination method to improve specificity, accuracy, detection levels, and run times through a more extensive enzymatic digestion to capture all available (or potentially available) carbohydrates. The digestion hydrolyzes all common sugars, starch, and starch derivatives down to their monosaccharide components, glucose, fructose, and galactose, which are then quantitated by high-performance anion-exchange chromatography with photodiode array detection. Method validation consisted of specificity testing and 10 days of analyzing various spike levels of mixed sugars, maltodextrin, and corn starch. The overall RSD was 4.0% across all sample types, which contained within-day and day-to-day components of 3.6 and 3.4%, respectively. Overall average recovery was 99.4% (n = 10). Average recovery for individual spiked samples ranged from 94.1 to 106% (n = 10). It is expected that the method could be applied to a variety of low-carbohydrate foods and beverages.

  4. Simultaneous determination of 13 carbohydrates using high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry.

    Science.gov (United States)

    Zhao, Dan; Feng, Feng; Yuan, Fei; Su, Jin; Cheng, Yan; Wu, Hanqiu; Song, Kun; Nie, Bo; Yu, Lian; Zhang, Feng

    2017-04-01

    A simple, accurate, and highly sensitive method was developed for the determination of 13 carbohydrates in polysaccharide of Spirulina platensis based on high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry. Samples were extracted with deionized water using ultrasonic-assisted extraction, and the ultrasound-assisted extraction conditions were optimized by Box-Behnken design. Then the extracted polysaccharide was hydrolyzed by adding 1 mol/L trifluoroacetic acid before determination by high-performance anion-exchange chromatography coupled with pulsed amperometric detection and confirmed by high-performance anion-exchange chromatography coupled with mass spectrometry. The high-performance anion-exchange chromatography coupled with pulsed amperometric detection method was performed on a CarboPac PA20 column by gradient elution using deionized water, 0.1 mol/L sodium hydroxide solution, and 0.4 mol/L sodium acetate solution. Excellent linearity was observed in the range of 0.05-10 mg/L. The average recoveries ranged from 80.7 to 121.7%. The limits of detection and limits of quantification for 13 carbohydrates were 0.02-0.10 and 0.2-1.2  μg/kg, respectively. The developed method has been successfully applied to ambient samples, and the results indicated that high-performance anion-exchange chromatography coupled with pulsed amperometric detection and mass spectrometry could provide a rapid and accurate method for the simultaneous determination of carbohydrates. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The impact of fouling on the process performance of the thermal treatment of pig slurry using tubular heat exchangers.

    Science.gov (United States)

    Cunault, C; Burton, C H; Pourcher, A M

    2013-03-15

    The aim of this study was to determine the kinetics of fouling and their influence on the performance of a thermal treatment process used for sanitisation of pig slurry. Two temperatures (55 °C and 80 °C) were investigated. One trial was carried out at 55 °C and 80 °C in which the slurry was not re-circulated and one trial at 80 °C in which 100% or 50% of the slurry was re-circulated. Fouling of the heat exchangers was assessed by on-line monitoring of the drop in pressure, changes in treatment temperature, heat transfer coefficients, heat recycling rate, and energy consumption. Similar energy consumption of around 38 kWh m(-3) of effluent was observed at the two temperatures. The operating periods prior to excessive fouling or blockage were 18 days at 55 °C and four days at 80 °C. Recycling treated manure to obtain 50% dilution of the raw feed increased the viable operating period to 14 days at 80 °C but doubled energy consumption. At 55 °C, the significant drop in the target temperature (>7 °C) with fouling severely jeopardised the process. The nature of the decline in performance suggests that the main fouling mechanisms were bio-fouling at 55 °C and organic/mineral deposits at 80 °C. Recycling treated manure enabled the operating period to be extended but increased the total cost of heating. One hundred percent recycling showed that the fouling potential of the manure was largely eliminated after one thermal treatment, suggesting a pretreatment may be advantageous. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Effect of Corporate Governance Structure on the Financial Performance of Johannesburg Stock Exchange (JSE-Listed Mining Firms

    Directory of Open Access Journals (Sweden)

    Isaih Dzingai

    2017-06-01

    Full Text Available There have been many corporate collapses and financial crises in recent years linked to a lack of effective corporate governance. The South African King IV Code of Corporate Governance recommends that corporate governing bodies should be comprised of an appropriate balance of knowledge, diversity, and independence for discharging their duties objectively and more efficiently. This study examines the effect of corporate governance structures on firm financial performance. The secondary data of selected Johannesburg Stock Exchange (JSE, Socially Responsible Investment (SRI Index-listed mining firms’ sustainability reports, and integrated annual financial statements are used. Using panel data analysis of the random effects model, we determined the relationship between board independence and board size and the return on equity (ROE for the period 2010–2015. Results indicate a weak negative correlation between ROE and board size, and a weak, but positive, correlation between ROE and board independence. Additionally, there is a positive, but weak, correlation between ROE and sales growth, but a negative and weak relationship between ROE and firm size. The study suggests that effective corporate governance through a small effective board and monitoring by an independent board result in increased firm financial performance. We recommend that South African companies see compliance with the recommendations of the King IV Code on Corporate Governance not as a liability, but an ethical investment that may likely yield financial benefit in the long-term. Although complying with corporate governance principles does not necessarily translate into a significant economic benefit, firms should, however, continue to adopt corporate governance for ethical reasons to meet stakeholder’s social and environmental needs for sustainable development.

  7. Resolution exchange simulation.

    Science.gov (United States)

    Lyman, Edward; Ytreberg, F Marty; Zuckerman, Daniel M

    2006-01-20

    We extend replica-exchange simulation in two ways and apply our approaches to biomolecules. The first generalization permits exchange simulation between models of differing resolution--i.e., between detailed and coarse-grained models. Such "resolution exchange" can be applied to molecular systems or spin systems. The second extension is to "pseudoexchange" simulations, which require little CPU usage for most levels of the exchange ladder and also substantially reduce the need for overlap between levels. Pseudoexchanges can be used in either replica or resolution exchange simulations. We perform efficient, converged simulations of a 50-atom peptide to illustrate the new approaches.

  8. Modelling and experimental validation for off-design performance of the helical heat exchanger with LMTD correction taken into account

    Energy Technology Data Exchange (ETDEWEB)

    Phu, Nguyen Minh; Trinh, Nguyen Thi Minh [Vietnam National University, Ho Chi Minh City (Viet Nam)

    2016-07-15

    Today the helical coil heat exchanger is being employed widely due to its dominant advantages. In this study, a mathematical model was established to predict off-design works of the helical heat exchanger. The model was based on the LMTD and e-NTU methods, where a LMTD correction factor was taken into account to increase accuracy. An experimental apparatus was set-up to validate the model. Results showed that errors of thermal duty, outlet hot fluid temperature, outlet cold fluid temperature, shell-side pressure drop, and tube-side pressure drop were respectively +-5%, +-1%, +-1%, +-5% and +-2%. Diagrams of dimensionless operating parameters and a regression function were also presented as design-maps, a fast calculator for usage in design and operation of the exchanger. The study is expected to be a good tool to estimate off-design conditions of the single-phase helical heat exchangers.

  9. Antiaging, photoprotective, and brightening activity in biorevitalization: a new solution for aging skin

    Directory of Open Access Journals (Sweden)

    Sparavigna A

    2015-02-01

    Full Text Available Adele Sparavigna, Beatrice Tenconi, Ileana De Ponti Derming, Clinical Research and Bioengineering Institute, Monza, Italy Background: Age-related changes in the dermis can be considered the result of intrinsic factors and the consequence of environmental damage, mainly due to ultraviolet (UV radiation from the sun (responsible for skin photoaging. The great versatility of the mesotherapy "biorevitalization" lies in the synergy between different biological effects of the active injected substances, which treats the skin in a more complete way. Several studies about biorevitalization efficacy showed good results. To date, however, objective results supported by instrumental evaluation are very sparse. Purpose: This study evaluated the efficacy of an injectable solution (32 mg of hyaluronic acid plus an antiaging antioxidant complex consisting of vitamins, minerals, and amino acids in the treatment of skin aging and photoaging. Methods: A total of 64 female volunteers (37–60 years underwent four sessions of biorevitalization at 3-week intervals, involving multiple injections in the face (external corner of the eye and cheek, neck, décolletage, and back of the hands. The esthetic result was assessed at baseline and after 6, 9, and 12 weeks, and was established through the use of clinical and instrumental evaluations, supported by photographic documentation. Additionally, a phototest was performed to assess the effect of biorevitalization treatment on UVB-induced erythema. Results: Instrumental assessment showed, as early as after the second biorevitalizing treatment, the antiaging efficacy of the tested product; there was a clinical and statistically significant improvement of profilometric parameters, skin brightness, pigmentation, and deep skin hydration. The study product induced a statistically significant decrease of the visual score of the UVB-induced erythema compared with baseline, which was statistically different from placebo

  10. Photochemical responses of three marine phytoplankton species exposed to ultraviolet radiation and increased temperature: role of photoprotective mechanisms.

    Science.gov (United States)

    Halac, S R; Villafañe, V E; Gonçalves, R J; Helbling, E W

    2014-12-01

    We carried out experiments using long-term (5-7 days) exposure of marine phytoplankton species to solar radiation, in order to assess the joint effects of ultraviolet radiation (UVR) and temperature on the photochemical responses and photoprotective mechanisms. In the experiments, carried out at Atlantic coast of Patagonia (43°18.7'S; 65°2.5'W) in spring-summer 2011, we used three species as model organisms: the dinoflagellate Prorocentrum micans, the chlorophyte Dunaliella salina and the haptophyte Isochrysis galbana. They were exposed under: (1) two radiation quality treatments (by using different filters): P (PAR, >400 nm) and PAB (PAR+UV-A+UV-B, >280 nm); (2) two radiation intensities (100% and 50%) and (3) two experimental temperatures: 18 °C and 23 °C during summer and 15 °C and 20 °C in spring experiments, simulating a 5 °C increase under a scenario of climate change. In addition, short-term (4h) artificial radiation exposure experiments were implemented to study vertical migration of cells pre- and non-acclimated to solar radiation. We observed species-specific responses: P. micans displayed a better photochemical performance and a lower inhibition induced by UVR than D. salina and I. galbana. In accordance, P. micans was the only species that showed a synthesis of UV-absorbing compounds (UVACs) during the experiment. On the other hand, non-photochemical quenching (NPQ) was activated in D. salina at noon throughout the exposure, while I. galbana did not show a regular NPQ pattern. This mechanism was almost absent in P. micans. Regarding vertical migration, I. galbana showed the most pronounced displacement to deepest layers since the first two hours of exposure in pre- and non-acclimated cells, while only non-acclimated D. salina cells moved to depth at the end of the experiment. Finally, temperature partially counteracted solar radiation inhibition in D. salina and I. galbana, whereas no effect was observed upon P. micans. In particular, significant

  11. Separation of seven arsenic species by ion-pair and ion-exchange high performance liquid chromatography

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Hansen, Sven Hedegaard

    1992-01-01

    Arsenite, arsenate, monomethylarsonate, dimethylarsinate, arsenobetaine, arsenocholine and the tetramethylarsonium ion were subjected to ion-exchange and ion-pair reversed phase HPLC. The ion exchange method was superior in selectivity and time of analysis for the arsenic anions. The ammonium ions...... used for the ion-pair method only resulted in separation of some of the anionic arsenic compounds. Flame atomic absorption spectrometry was used for on-line arsenic-specific detection....

  12. Enhanced catalytic performance of copper-exchanged SAPO-34 molecular sieve in methanol-to-olefin reaction.

    Science.gov (United States)

    Kim, Sun Jung; Park, Ji Won; Lee, Kwang Young; Seo, Gon; Song, Mee Kyung; Jeong, Soon-Yong

    2010-01-01

    Methanol-to-olefin (MTO) reaction over copper-exchanged SAPO-34 catalysts was investigated in order to extend their catalyst life. The exchange of copper ions into the cages of an SAPO-34 molecular sieve was confirmed by ESR, XPS, and 129Xe NMR techniques. Copper ions located in its cages considerably reduced its deactivation rate in the MTO reaction, while those dispersed on the external surface of the SAPO-34 molecular sieve accelerated the deactivation due to the limited mass transfer through the pore entrances. The 13C NMR and UV-VIS spectroscopy investigations of the materials occluded on the copper-exchanged SAPO-34 catalysts during the MTO reaction clearly showed that the copper ions exchanged in the cages suppressed the further condensation of alkyl aromatics to large, fused polycyclic aromatic hydrocarbons (PAHs). Theoretical calculations for the SAPO-34 and copper-exchanged SAPO-34 molecular sieves supported this observation because copper ions located in the cages stabilized the alkyl aromatics. Therefore, the exchange of copper ions into the SAPO-34 molecular sieve stabilized the reactive intermediates, alkyl aromatics, of the MTO reaction and suppressed their further condensation to PAHs, thereby slowing the deactivation.

  13. Water vapor exchange system using a hydrophilic microporous layer coated gas diffusion layer to enhance performance of polymer electrolyte fuel cells without cathode humidification

    Science.gov (United States)

    Kitahara, Tatsumi; Nakajima, Hironori; Morishita, Masashi

    2012-09-01

    Polymer electrolyte fuel cells (PEFCs) generally have external humidifiers to supply humidified hydrogen and oxidant gases, which prevents dehydration of the membrane. If a PEFC could be operated without humidification, then external humidifiers could be removed, which would result in a simplified PEFC system with increased total efficiency and reduced cost. A water vapor exchange system installed in the PEFC was developed to enhance the performance without cathode humidification. A gas diffusion layer (GDL) coated with a hydrophobic microporous layer (MPL) was used at the active reaction area. A GDL coated with a hydrophilic MPL consisting of polyvinyl alcohol (PVA) and carbon black was used at the cathode water vapor exchange area to promote water transport from the cathode outlet wet gas to the anode inlet dry gas. This is effective for reducing the IR overpotential, which enhances the PEFC performance. Appropriate enhancement of hydrophilicity by increasing the PVA content in the MPL to 20 mass% is effective to increase water transport from the cathode to anode. At the anode water exchange area, a GDL without the hydrophilic MPL is effective to promote water transport from the water exchange area to the active reaction area, which enhances the PEFC performance.

  14. Performance Evaluation of AI2O3/Water Nanofluid as Coolant in a Double-Tube Heat Exchanger Flowing under a Turbulent Flow Regime

    Directory of Open Access Journals (Sweden)

    Navid Bozorgan

    2012-01-01

    Full Text Available Nanofluids are expected to be a promising coolant candidate in chemical processes for water waste remediation and heat transfer system size reduction. This paper focuses on the potential mass flowrate reduction in exchanger with a given heat exchange capacity using nanofluids. Al2O3 nanoparticles with diameters of 7 nm dispersed in water with volume concentrations up to 2% are selected as a coolant, and their performance in a horizontal double-tube counterflow heat exchanger under turbulent flow conditions is numerically studied. The results show that the flowrate of nanofluid coolant decreases with the increase of concentration of nanoparticles in the exchanger with a given heat exchange capacity. The mass flowrate of the nanofluid at a volume concentration of 2 vol.% is approximately 24.5% lower than that of pure water (base fluid for given conditions. For the pressure drop, the results show that the pressure drop of nanofluid is slightly higher than water and increases with increase of volume concentrations. In addition, the reduction of wall temperature and heat transfer area is estimated.

  15. Fernblock, a Nutriceutical with Photoprotective Properties and Potential Preventive Agent for Skin Photoaging and Photoinduced Skin Cancers

    Directory of Open Access Journals (Sweden)

    Angeles Juarranz

    2011-11-01

    Full Text Available Many phytochemicals are endowed with photoprotective properties, i.e., the capability to prevent the harmful effects of excessive exposure to ultraviolet (UV light. These effects include photoaging and skin cancer, and immunosuppression. Photoprotection is endowed through two major modes of action: UV absorption or reflection/scattering; and tissue repair post-exposure. We and others have uncovered the photoprotective properties of an extract of the fern Polypodium leucotomos (commercial name Fernblock. Fernblock is an all-natural antioxidant extract, administered both topically (on the skin or orally. It inhibits generation of reactive oxygen species (ROS production induced by UV including superoxide anion. It also prevents damage to the DNA, inhibits UV-induced AP1 and NF-κB, and protects endogenous skin natural antioxidant systems, i.e., CAT, GSH, and GSSR. Its photoprotective effects at a cellular level include a marked decrease of UV-mediated cellular apoptosis and necrosis and a profound inhibition of extracellular matrix remodeling. These molecular and cellular effects translate into long-term inhibition of photoaging and carcinogenesis that, together with its lack of toxicity, postulate its use as a novel-generation photoprotective nutriceutical of phytochemical origin.

  16. Effects of sulfonated polyether-etherketone (SPEEK) and composite membranes on the proton exchange membrane fuel cell (PEMFC) performance

    Energy Technology Data Exchange (ETDEWEB)

    Erce Senguel; Erdener, Huelya; Akay, R. Gueltekin; Yuecel, Hayrettin; Eroglu, inci [Chemical Engineering Department, Middle East Technical University, 06531 Ankara (Turkey); Bac, Nurcan [Chemical Engineering Department, Yeditepe University, 34755 Istanbul (Turkey)

    2009-05-15

    Sulfonated polyether-etherketone (SPEEK) has a potential for proton exchange fuel cell applications. However, its conductivity and thermohydrolytic stability should be improved. In this study the proton conductivity was improved by addition of an aluminosilicate, zeolite beta. Moreover, thermohydrolytic stability was improved by blending poly-ether-sulfone (PES). Sulfonated polymers were characterized by H-NMR. Composite membranes prepared were characterized by Electrochemical Impedance Spectroscopy (EIS) for their proton conductivity. Degree of sulfonation (DS) values calculated from H-NMR results, and both proton conductivity and thermohydrolytic stability was found to strongly depend on DS. Therefore, DS values were controlled time in the range of 55-75% by controlling the reaction time. Zeolite beta fillers at different SiO{sub 2}/Al{sub 2}O{sub 3} ratios (20, 30, 40, 50) were synthesized and characterized by XRD, EDX, TGA, and SEM. The proton conductivity of plain SPEEK membrane (DS = 68%) was 0.06 S/cm at 60 C and the conductivity of the composite membrane containing of zeolite beta filled SPEEK was found to increase to 0.13 S/cm. Among the zeolite Beta/SPEEK composite membranes the best conductivity results were achieved with zeolite beta having a SiO{sub 2}/Al{sub 2}O{sub 3} ratio of 50 at 10 wt% loading. Single fuel cell tests performed at different operating temperatures indicated that SPES/SPEEK membrane is more stable hydrodynamically and also performed better than pristine SPEEK membranes which swell excessively. Membrane electrode assemblies (MEAs) were prepared by gas diffusion layer (GDL) spraying method. The highest performance of 400 mA/cm{sup 2} was obtained for SPEEK membrane (DS 56%) at 0.6 V for a H{sub 2}-O{sub 2}/PEMFC working at 1 atm and 70 C. At the same conditions Nafion {sup registered} 112 gave 660 mA/cm{sup 2}. It was observed that the operating temperature can be increased up to 90 C with polymer blends containing poly

  17. [High speed separation and quantitation of Ralstonia solanacearum of different virulence using high performance ion exchange chromatography].

    Science.gov (United States)

    Lin, Juan; Ma, Cheng; Liu, Shutao; Wu, Lingling; Rao, Pingfan

    2007-01-01

    High performance ion exchange chromatography coupled with laser light scattering instrument was employed for the rapid separation and quantitation of Ralstonia solanacearum of different virulence. The pure culture of Ralstonia solanacearum was successfully separated into three characteristic fractions. Each fraction was collected and inoculated onto 2,3,5-triphenyltetrazolium chloride (TTC) plates to identify its virulence. The shapes and colors of the colonies were imaged, and the average attenuation index (attenuation index = red spot diameter of colony/total colony diameter) of ten colonies of each fraction was carefully determined. Furthermore, each fraction was inoculated into SPA liquid media at 30 degrees C with shaking (200 r/min) for 48 h, the cells were harvested, suspended at a density of 1.2 x 10(9) cfu/mL, and applied to infect tomato tissue culture plantlets using leaf-cutting method. The infection mortality of the tomato tissue culture plantlets was recorded from 1 to 9 days after inoculation. The results showed that the virulences of each fraction were different on the basis of attenuation index and infection mortality. The virulence of peak 3 fraction was the strongest. On the contrary, the virulence of peak 1 fraction was the weakest. In addition, the linear relationships between different injection volumes (1 - 180 microL) and their peak areas were investigated. The linearity was good within the range of the bacterial number of 9 x 10(6) - 9 x 10(8) (r = 0.99). This method can be potentially used as a novel tool for the rapid separation and quantitation of Ralstonia solanacearum of different virulences.

  18. Barter exchanges

    DEFF Research Database (Denmark)

    Sudzina, Frantisek

    Although barter is often perceived as something that proceeded money, barter is still used. The focus of the paper is on barter exchanges. Barter exchanges are used both in developing countries as well as in developed countries (including the U.S.). They are used by both organizations...... and individuals. They usually allow to exchange good but some include also services. Some exchanges allow only for bi-directional barter, i.e. when only two parties are involved in the exchange. But probably most of the barter exchanges use barter money; this makes it easier to exchange goods and services...

  19. [Determination of succinic acid in desvenlafaxine succinate by high performance ion-exclusion chromatography and high performance ion-exchange chromatography].

    Science.gov (United States)

    Zong, Yanping; Li, Jinghua; Sun, Wei; Liu, Guixia; Lu, Jinghua; Shan, Guangzhi

    2016-02-01

    New methods were developed for the determination of succinic acid in desvenlafaxine succinate (DVS) by high performance ion-exclusion chromatography (HPIEC) and high performance ion-exchange chromatography (HPIC). HPIEC and HPIC methods were used separately to determinate the succinic acid in DVS. With HPIEC, the sample was diluted with 2. 50 x 10(-3) mol/L sulfuric acid solution and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIEC directly without any further pretreatment. The analytical column was Phenomenex Rezex ROA-organic Acid H+(8%) (300 mmx7. 8 mm). The mobile phase was 2. 50x10(-3) mol/L sulfuric acid solution at the flow rate of 0. 5 mL/min. The column temperature was set at 40 °C, and the detection wavelength was 210 nm. The injection volume was 10 KL. The assay was quantified by external standard method. With HPIC, the sample was diluted with ultrapure water and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIC directly without any further pretreatment. The analytical column was Dionex IonPac AS11-HC (250 mm x 4 mm) with a guard column IonPacAG11-HC (50 mm x 4 mm). Isocratic KOH elute generator was used at the flow rate of 1. 0 mL/min. The detection was performed by a Dionex suppressed (DIONEX AERS 500 4-mm) conductivity detector. The injection volume was 10 µL. The content computation was performed with peak area external reference method. The results of HPIEC method for succinic acid were 28. 8%, 28. 9% and 28. 9%, while the results of HPIEC method were 28. 2%, 28. 6% and 28. 6%. The results of HPIEC and HPIC methods were not significantly different. The two methods can both be used to determine the contents of succinic acid in DVS. The surveillance analytical method should be chosen according to the situation.

  20. Performance testing of the AST-50O model of district heating network heat exchanger with 08Cr14 steel tubes

    Energy Technology Data Exchange (ETDEWEB)

    Afanas' ev, A.A.; Borisov, V.P.; Grebennikov, V.N.; Dolinin, E.L.; Krutikov, P.G.; Shishkunov, V.A.; Stogov, V.I.

    1984-02-01

    Test results of network heat exchanger model of a nuclear boiler plant AST-500 with a tube part of 08Kh14MF ferritic-martensitic steel are presented. The model presents a one-through counterflow water-water heat-exchanger. The model was connected to the district heating network where it operated for 5000 hr at pH=7.3 and at the temperature 70-90 deg C. Rolled joints ''tube-tube sheet'' did not have traces of contact corrosion, gradual corrosion of 08Kh14MF steel did not exceed 0 003 mm/year, which ensured normal working capacity of heat-exchanger equipment for the planned 30 years.

  1. Effect of Louver Angle on Performance of Heat Exchanger With Serpentine Fins and Flat Tubes in Periodic Frosting

    OpenAIRE

    Hrnjak, Predrag S.; Zhang, Ping; Rennels, Chris

    2012-01-01

    This paper presents the results of an experimental study on the air-side pressure drop and overall heat transfer coefficient characteristics for serpentine-louvered-fin, microchannel heat exchanger in periodic frosting. It focuses on quantification of the effects of louver angle on heat transfer and pressure drop and on defrost and refrost times. Nine heat exchangers differing in louver angle and fin pitch (i.e. louver angle 15º to 39º and fin pitch 15 to 18 fpi) are studied. The face velocit...

  2. Cation-exchange high-performance liquid chromatography: Separation of highly basic proteins using volatile acidic solvents

    NARCIS (Netherlands)

    Eijnden-van Raaij, A.J.M. van den; Koornneef, I.; Oostwaard, Th.M.J.; Laat, S.W. de; Zoelen, E.J.J. van

    1987-01-01

    The chromatographic behavior of a number of globular proteins was studied on a Bio-Sil TSK CM-2-SW weak cation exchange HPLC column under acidic conditions. A linear gradient of O-I M NH₄Ac in I M HOAc, inducing a convex pH gradient from 2.4-4.8, resulted in an excellent separation of highly

  3. Performance Evaluation of a Helical Coil Heat Exchanger Working under Supercritical Conditions in a Solar Organic Rankine Cycle Installation

    Directory of Open Access Journals (Sweden)

    Marija Lazova

    2016-06-01

    Full Text Available Worldwide interest in low grade heat valorization using organic Rankine cycle (ORC technologies has increased significantly. A new small-scale ORC with a net capacity of 3 kW was efficiently integrated with a concentrated solar power technology for electricity generation. The excess heat source from Photovoltaic (PV collectors with a maximum temperature of 100 °C was utilized through a supercritical heat exchanger that uses R-404A as working medium. By ensuring supercritical heat transfer leads to a better thermal match in the heat exchanger and improved overall cycle efficiency. A helical coil heat exchanger was designed by using heat transfer correlations from the literature. These heat transfer correlations were derived for different conditions than ORCs and their estimated uncertainty is ~20%. In order to account for the heat transfer correlation uncertainties this component was oversized by 20%. Next, a prototype was built and installed in an integrated concentrated photovoltaic/thermal (CPV/T/Rankine system. The results from the measurements show that for better estimation of the sizing of the heat exchanger a more accurate correlation is required in order to design an optimal configuration and thus employ cheaper components.

  4. On the Experimental Investigation of the Clamping Pressure Effects on the Proton Exchange Membrane Water Electrolyser Cell Performance

    DEFF Research Database (Denmark)

    Al Shakhshir, Saher; Frensch, Steffen Henrik; Kær, Søren Knudsen

    2017-01-01

    energy sources. The proton exchange membrane water electrolyser(PEMWE) is the most candidate technology to produce hydrogen from renewable energysources. PEMWE cell splits water into hydrogen and oxygen when an electric current is passedthrough it. Electrical current forces the positively charged ions...

  5. Performance and life cycle environmental benefits of recycling spent ion exchange brines by catalytic treatment of nitrate.

    Science.gov (United States)

    Choe, Jong Kwon; Bergquist, Allison M; Jeong, Sangjo; Guest, Jeremy S; Werth, Charles J; Strathmann, Timothy J

    2015-09-01

    Salt used to make brines for regeneration of ion exchange (IX) resins is the dominant economic and environmental liability of IX treatment systems for nitrate-contaminated drinking water sources. To reduce salt usage, the applicability and environmental benefits of using a catalytic reduction technology to treat nitrate in spent IX brines and enable their reuse for IX resin regeneration were evaluated. Hybrid IX/catalyst systems were designed and life cycle assessment of process consumables are used to set performance targets for the catalyst reactor. Nitrate reduction was measured in a typical spent brine (i.e., 5000 mg/L NO3(-) and 70,000 mg/L NaCl) using bimetallic Pd-In hydrogenation catalysts with variable Pd (0.2-2.5 wt%) and In (0.0125-0.25 wt%) loadings on pelletized activated carbon support (Pd-In/C). The highest activity of 50 mgNO3(-)/(min - g(Pd)) was obtained with a 0.5 wt%Pd-0.1 wt%In/C catalyst. Catalyst longevity was demonstrated by observing no decrease in catalyst activity over more than 60 days in a packed-bed reactor. Based on catalyst activity measured in batch and packed-bed reactors, environmental impacts of hybrid IX/catalyst systems were evaluated for both sequencing-batch and continuous-flow packed-bed reactor designs and environmental impacts of the sequencing-batch hybrid system were found to be 38-81% of those of conventional IX. Major environmental impact contributors other than salt consumption include Pd metal, hydrogen (electron donor), and carbon dioxide (pH buffer). Sensitivity of environmental impacts of the sequencing-batch hybrid reactor system to sulfate and bicarbonate anions indicate the hybrid system is more sustainable than conventional IX when influent water contains reuse cycles. The study showed that hybrid IX/catalyst reactor systems have potential to reduce resource consumption and improve environmental impacts associated with treating nitrate-contaminated water sources. Copyright © 2015 Elsevier Ltd. All rights

  6. Exploring the Impact of ISO 9001, ISO 14001 and OHSAS 18001 Certification on Financial Performance: The Case of Companies listed on the Bucharest Stock Exchange

    Directory of Open Access Journals (Sweden)

    Mihaela Ionașcu

    2017-02-01

    Full Text Available The purpose of this paper is to investigate the impact of ISO 9001, ISO 14001 and OHSAS 18001 certification on the financial performance of Romanian companies listed on the Bucharest Stock Exchange (BSE. Based on audited financial statements of a population of 67 non-financial companies listed during 2013-2015 and using regression models, this paper shows, for the first time in Romania, that companies listed on BSE, implementing complex management systems (quality – environmental and/or occupational health and safety perform better, and that their performance is directly linked to the complexity of the management systems implemented.

  7. The effect of shape of winglet vortex generator on the thermal-hydrodynamic performance of a circular tube bank fin heat exchanger

    Science.gov (United States)

    Hu, Wanling; Wang, Liangbi; Guan, Yong; Hu, Wenju

    2017-09-01

    In real application, the shape of the vortex generator has great influence on the heat transfer and flow resistance characteristics of tube bank fin heat exchanger. Therefore, the effect of the shape of the vortex generator on heat transfer performance of such heat exchanger should be considered. In this paper, the effect of three different shaped vortex generators (i.e. delta winglet, rectangular winglet and trapezoid winglet) on heat transfer intensity and secondary flow intensity of a circular tube bank fin heat exchanger was numerically studied. The results show that with increasing Re, overall average Nu and the non-dimensional secondary flow intensity Se m increase however friction factor f decreases. A corresponding relationship can be found between Nu and Se m, which indicates that the secondary flow intensity determines the heat transfer intensity in the fin-side channel of circular tube bank fin heat exchanger with different shaped vortex generators on the fin surfaces. Under the identical pumping power constrain, the optimal shape of the vortex generators is the delta winglet vortex generators for the studied cases.

  8. An analysis of cryotrap heat exchanger performance test data (400 area) and recommendations for a system to handle Apollo RCS engines

    Science.gov (United States)

    Rakow, A.

    1983-01-01

    The current arrangement of a Platecoil heat exchanger which uses LN2 on the inside of parallel tubes, in counter flow to the test cell engine exhaust gases which are drawn through a box surrounding the plates by the existing vacuum blowers is examined. As a result of inadequate performance and special test data it was decided to redesign the system to accommodate an Apollo RCS engine.

  9. Microtube strip heat exchanger

    Science.gov (United States)

    Doty, F. D.

    1991-07-01

    During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchanger. The DSI completed a heat exchanger stress analysis of the ten-module heat exchanger bank; and performed a shell-side flow inhomogeneity analysis of the three-module heat exchanger bank. The company produced 50 tubestrips using an in-house CNC milling machine and began pressing them onto tube arrays. The DSI revised some of the tooling required to encapsulate a tube array and press tubestrips into the array to improve some of the prototype tooling.

  10. Air/ground heat exchanger (GHE): Modelling, design, performance; Luft-/Erdwaermetauscher EWT: Modellierung, Auslegung und Betriebserfahrungen

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, A. [Fraunhofer-Inst. fuer Solare Energiesysteme, Freiburg (Germany); Pfafferott, J. [Energieversorgung Spree-Schwarze Elster AG (ESSAG), Cottbus (Germany); Dibowski, G. [Deutsches Zentrum fuer Luft- und Raumfahrt e.V. (DLR), Koeln (Germany). Abt. Sonnenofen

    1998-02-01

    Air/Ground Heat Exchanger (GHE) utilize soil for seasonal heat storage and are used for air preheating or -cooling. Design and layout require suitable tools which adequately describe the complex heat temperature mechanisms in soils. Since heat densities in soil and heat exchange coefficients between air and GHE are both low, a detailed characterization of the soil and a precise modeling of the heat exchange processes within the GHE are needed. Tools for the design and yield prediction of GHE are presented by way of examples. Results are compared with measured data and both opportunities and limitations of GHEs are discussed using calculated and actual data. (orig.) [Deutsch] Luft-/Erdwaermetauscher EWT nutzen das Erdreich als saisonalen Energiespeicher, sie werden beispielsweise zur Zuluft-Vorerwaermung oder -kuehlung eingesetzt. Die Planung und Auslegung von Luft-/Erdwaermetauschern erfordert geeignete Hilfsmittel, um das komplizierte Temperaturfeld im Erdreich mit ausreichender Genauigkeit abbilden zu koennen. Da die Waermestromdichten im Erdreich und der Waermeuebergang zwischen der Luft im Luft-/Erdwaermetauscher und dem umgebenden Erdreich gering sind, ist sowohl eine detaillierte Abbildung des Erdreichs als auch die Modellierung des Waermeuebergangs im Luft-/Erdwaermetauscher erforderlich. Verfahren zur Auslegung und Ertragsvorhersage von Luft-/Erdwaermetauschern werden vorgestellt und deren Anwendung demonstriert. Die Ergebnisse werden mit Betriebserfahrungen von realisierten Luft-/Erdwrmetauschern verglichen. Moeglichkeiten und Grenzen von Luft-/Erdwaermetauschern werden anhand von Praxis und Simulationsrechnungen diskutiert. (orig.)

  11. Development of a dose assay for a Clostridium difficile vaccine using a tandem ion exchange high performance liquid chromatography method.

    Science.gov (United States)

    Wang, Feng; Ha, Sha; Rustandi, Richard R

    2017-05-19

    Clostridium difficile is a gram-positive intestine bacterium that causes a severe diarrhea and could eventually be lethal. The main virulence factor is related to the release of two major exotoxins, toxin A (TcdA) and toxin B (TcdB). Recent C. difficile-associated disease (CDAD) outbreaks have been caused by hypervirulent strains which secrete an additional binary toxin (CDTa/CDTb). Vaccination against these toxins is considered the best way to combat the CDAD. Recently, a novel tetravalent C. difficile vaccine candidate containing all four toxins produced from a baculovirus expression system has been developed. A dose assay to release this tetravalent C. difficile vaccine was developed using tandem ion-exchange HPLC chromatography. A sequential weak cation exchange (carboxyl group) and weak anion exchange (tertiary amine group) columns were employed. The four C. difficile vaccine antigen pIs range from 4.4 to 8.6. The final optimized separation employs salt gradient elution at two different pHs. The standard analytical parameters such as LOD, LOQ, linearity, accuracy, precision and repeatability were evaluated for this method and it was deemed acceptable as a quantitative assay for vaccine release. Furthermore, the developed method was utilized for monitoring the stability of the tetravalent C. difficile vaccine in final container. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Photoprotection and recovery of photosystem II in the Southern Ocean phytoplankton

    Science.gov (United States)

    Katayama, Tomoyo; Makabe, Ryosuke; Sampei, Makoto; Hattori, Hiroshi; Sasaki, Hiroshi; Taguchi, Satoru

    2017-06-01

    The future shoaling of surface mixed layer depth due to global warming will expose natural assemblages of phytoplankton to increased mean light. Under these conditions, photoprotective acclimation against high light can determine ecological success. We investigated photoprotective responses to sunlight and recovery from photodamage of photosystem II (PSII) in natural assemblages north and south of the Polar Front (PF). The decrease in the maximum quantum yield (Fv/Fm) of PSII during direct sunlight exposure for 2 h was moderated progressively by the enhancement of diatoxanthin synthesis. When the light-exposed cells were incubated under three reduced light conditions, Fv/Fm recovered to more than the initial values north of the PF but did not reach initial values south of the PF. Temperatures higher in the north than the south of the PF could have induced the faster recovery from photodamage of PSII in assemblages north of the PF. These northern assemblages may be able to acclimate to fast-changing light conditions.

  13. Evaluation of benefit to educational material for photoprotection in those with cutaneous lupus erythematosus.

    Science.gov (United States)

    Kaushik, Anshika; Laumann, Anne; Nwe, Steven; Kwasny, Mary J; West, Dennis P; Kundu, Roopal V

    2015-04-01

    Photosensitivity (PS) in cutaneous lupus erythematosus (CLE) contributes to decreased quality of life (QoL). We aimed to assess baseline knowledge about sun protection in persons with CLE and identify knowledge differences by race. Additionally, we aimed to determine the impact of a verbal educational intervention on photoprotection and CLE. 31 adults with CLE were recruited from an academic-based dermatology clinic and completed a 17-item questionnaire about CLE and sun protection at three time points: pre- intervention (PR-I), post-intervention (PO-I), and 3-month phone follow up (3MF). An educational intervention using American Academy of Dermatology CLE and sun protection education materials was delivered between PR-I and PO-I. 31 subjects participated at PR-I and PO-I, and 25 subjects (81%) at 3MF. Baseline CLE-related PS and photoprotection knowledge differed significantly by race, with non-Caucasians demonstrating less knowledge (P= 0.049). Knowledge about sun exposure being linked to lupus increased from 81% to 97% (P=0.25) between PR-I and PO-I. At PR-I, 19% agreed that smoking was linked to lupus compared to 90% PO-I (Peducational intervention successfully improved immediate lupus-related PS and sun exposure knowledge, but knowledge was not retained long-term. It appears educational materials must be improved.

  14. A Powerful Mitochondria-Targeted Iron Chelator Affords High Photoprotection against Solar Ultraviolet A Radiation.

    Science.gov (United States)

    Reelfs, Olivier; Abbate, Vincenzo; Hider, Robert C; Pourzand, Charareh

    2016-08-01

    Mitochondria are the principal destination for labile iron, making these organelles particularly susceptible to oxidative damage on exposure to ultraviolet A (UVA, 320-400 nm), the oxidizing component of sunlight. The labile iron-mediated oxidative damage caused by UVA to mitochondria leads to necrotic cell death via adenosine triphosphate depletion. Therefore, targeted removal of mitochondrial labile iron via highly specific tools from these organelles may be an effective approach to protect the skin cells against the harmful effects of UVA. In this work, we designed a mitochondria-targeted hexadentate (tricatechol-based) iron chelator linked to mitochondria-homing SS-like peptides. The photoprotective potential of this compound against UVA-induced oxidative damage and cell death was evaluated in cultured primary skin fibroblasts. Our results show that this compound provides unprecedented protection against UVA-induced mitochondrial damage, adenosine triphosphate depletion, and the ensuing necrotic cell death in skin fibroblasts, and this effect is fully related to its potent iron-chelating property in the organelle. This mitochondria-targeted iron chelator has therefore promising potential for skin photoprotection against the deleterious effects of the UVA component of sunlight. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Antioxidant and Photoprotective Effects of Blanch Water, a Byproduct of the Almond Processing Industry

    Directory of Open Access Journals (Sweden)

    Francesco Paolo Bonina

    2013-10-01

    Full Text Available The aim of the present work was to evaluate the antioxidant and photoprotective effect of blanch water (BW, a byproduct of the almond processing industry. The polyphenolic content of a BW extract, the level of proanthocyanidins and the vanillin index determination were determined. The antioxidant activity and the radical scavenging activity of the BW were evaluated by a range of in vitro tests. The in vivo photoprotective effect was investigated using a formulation containing 2% of the BW extract on skin erythema induced by acute UV-B exposure in twelve volunteers. Results confirmed the presence of added-value antioxidant compounds in the industrial BW extract, and the most representative compounds were naringenin-7-O-glucoside and kaempferol-7-O-rutinoside. The proanthocyanidin content was 71.84 ± 5.21 cyanidin equivalents/g of BW extract. The good antiradical activity of the BW extract was demonstrated in both the DPPH• test and in the Reducing Power test. The percentage inhibition of erythema obtained using a formulation of BW was 50.48, value clearly demonstrating an effect against photooxidative damage in vivo.

  16. Dried extracts of Encholirium spectabile (Bromeliaceae) present antioxidant and photoprotective activities in vitro

    Science.gov (United States)

    de Oliveira, Raimundo Gonçalves; Souza, Grasielly Rocha; Guimarães, Amanda Leite; de Oliveira, Ana Paula; Silva Morais, Amanda Caroline; da Cruz Araújo, Edigênia Cavalcante; Nunes, Xirley Pereira; Almeida, Jackson Roberto Guedes da Silva

    2013-01-01

    The antioxidant and photoprotective activities of dried extracts from the leaves of Encholirium spectabile were investigated. It was also evaluated the total phenolic and flavonoid contents by the Folin–Ciocalteu and aluminum chloride methods, respectively. Antioxidant activities of the extracts were evaluated by using of 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging and β-carotene–linoleic acid bleaching and compared with ascorbic acid, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) used as reference compounds. The photoprotective effect was evaluated by the spectrophotometric method. The most significant total phenolic and flavonoid contents was of 188.50 ± 27.50 mg of gallic acid equivalent/g and 129.70 ± 4.59 mg of catechin equivalent/g, respectively, for chloroform fraction (Es-CHCl3). The Es-CHCl3 also presented the best antioxidant activity (IC50 25.35 ± 4.35 μg/ml) for DPPH scavenging. The ethanol extract (Es-EtOH), Es-CHCl3 and the fraction ethyl acetate (Es-AcOEt) showed characteristic absorption bands in regions UVB and UVA in a concentration-dependent manner. Es-CHCl3 presented the highest sun protection factor SPF (8.89 ± 2.11). It shows the possibility to use this extract as sunscreen in pharmaceutical preparations. PMID:24396251

  17. Antioxidant, photoprotective and antimutagenic properties of Phyllanthus spp. from Cuban flora

    Directory of Open Access Journals (Sweden)

    Ivette M. Menéndez-Perdomo

    2017-08-01

    Full Text Available Context: Sunlight ultraviolet (UV radiation constitutes a significant physical carcinogen in nature. It could induce direct and indirect DNA damage, which if not properly repaired may generate mutations. Plants in the genus Phyllanthus (Phyllanthaceae are widely used in traditional medicine and known as natural sources of antioxidant compounds. Recent investigations support their genoprotective activity against chemical and physical mutagens, among them UV radiation. Aims: To compare the antioxidant, photoprotective and antimutagenic activity of aqueous extracts obtained from three Cuban endemic Phyllanthus species: P. chamaecristoides Urb., P. microdictyus Urb., and P. williamioides Gr. Methods: DPPH radical scavenging assay was use for quantify the in vitro antioxidant capacity. Genoprotection against UVC radiation was measured at two levels: structural DNA damage and mutations, by means of the SOS Chromotest, Survival assay, and RifR mutagenicity test in Caulobacter crescentus cells. Results: P. chamaecristoides extract showed the highest antioxidant capacity (IC50 = 0.032 mg/mL, and together with P. microdictyus exhibited the greatest bioantimutagenic effects (RMF ≤ 5%, diminishing UVC-induced DNA damage in three and five times, respectively. Conclusions: The reduction in DNA damage is not founded in a Phyllanthus aqueous extracts desmutagenic effect. It is possible that the genoprotective activity detected could be due to modulation of DNA repair mechanisms, diminishing SOS response and related mutagenicity induced by UVC radiation. Moreover, high antioxidant capacity could also decrease UV radiation oxidative-damage. Altogether, these outcomes validate future pre-clinic research regarding Phyllanthus photoprotective capacities.

  18. Assessing the photoprotective effects of red ochre on human skin by in vitro laboratory experiments

    Directory of Open Access Journals (Sweden)

    Riaan F. Rifkin

    2015-03-01

    Full Text Available Archaeological indicators of cognitive complexity become increasingly prevalent during the African Middle Stone Age, with the habitual exploitation of red ochre widely viewed as a key feature of the emergence of modern human behaviour. Given that some of the uses of ochre remain ambiguous, we present the preliminary results of an ongoing study in which we explore the efficacy of red ochre as a photoprotective device or sunscreen. The capacity of ochre to inhibit the susceptibility of humans to the detrimental effects of ultraviolet radiation was confirmed through the in vitro calculation of the sun protection factor values of samples derived from the Kunene Region in Namibia and the Bokkeveld Group deposits, Western Cape Province, South Africa. Visible spectroscopy was employed to determine colourimetric parameters of samples and assess the correlation between ochre colour and sun protection factor. The possible role of ochre as a sunscreen agent for hominin populations, including modern humans, during the Middle Stone Age in Africa is explored. We conclude that the habitual use of red ochre as a photoprotective agent likely played a role in the ability of prehistoric humans to adapt to novel environmental circumstances.

  19. Dunaliella tertiolecta (Chlorophyta) Avoids Cell Death Under Ultraviolet Radiation By Triggering Alternative Photoprotective Mechanisms.

    Science.gov (United States)

    Segovia, María; Mata, Teresa; Palma, Armando; García-Gómez, Candela; Lorenzo, Rosario; Rivera, Alicia; Figueroa, Félix L

    2015-11-01

    The effect of different ultraviolet radiation (UVR) treatments combining PAR (P), UVA (A) and UVB (B) on the molecular physiology of Dunaliella tertiolecta was studied during 6 days to assess the response to chronic UVR exposure. UVR reduced cell growth but did not cause cell death, as shown by the absence of SYTOX Green labeling and cellular morphology. However, caspase-like enzymatic activities (CLs), (regarded as cell death proteases), were active even though the cells were not dying. Maximal quantum yield of fluorescence (Fv /Fm ) and photosynthetic electron transport rate (ETR) dropped. Decreased nonphotochemical quenching (NPQ) paralleled a drop in xanthophyll cycle de-epoxidation under UVB. Reactive oxygen species (ROS) and D1 protein accumulation were inversely correlated. PAB exhibited elevated ROS production at earlier times. Once ROS decayed, D1 protein recovered two-fold compared with P and PA at later stages. Therefore, PsbA gene was still transcribed, suggesting ROS involvement in D1 recovery by its direct effect on mRNA-translation. We add evidence of an UVB-induced positive effect on the cells when P is present, providing photoprotection and resilience, by means of D1 repair. This allowed cells to survive. The photoprotective mechanisms described here (which are counterintuitive in principle) conform to an important ecophysiological response regarding light stress acclimation. © 2015 The American Society of Photobiology.

  20. Bipyrimidine Signatures as a Photoprotective Genome Strategy in G + C-rich Halophilic Archaea

    Directory of Open Access Journals (Sweden)

    Daniel L. Jones

    2016-09-01

    Full Text Available Halophilic archaea experience high levels of ultraviolet (UV light in their environments and demonstrate resistance to UV irradiation. DNA repair systems and carotenoids provide UV protection but do not account for the high resistance observed. Herein, we consider genomic signatures as an additional photoprotective strategy. The predominant forms of UV-induced DNA damage are cyclobutane pyrimidine dimers, most notoriously thymine dimers (T^Ts, which form at adjacent Ts. We tested whether the high G + C content seen in halophilic archaea serves a photoprotective function through limiting T nucleotides, and thus T^T lesions. However, this speculation overlooks the other bipyrimidine sequences, all of which capable of forming photolesions to varying degrees. Therefore, we designed a program to determine the frequencies of the four bipyrimidine pairs (5’ to 3’: TT, TC, CT, and CC within genomes of halophilic archaea and four other randomized sample groups for comparison. The outputs for each sampled genome were weighted by the intrinsic photoreactivities of each dinucleotide pair. Statistical methods were employed to investigate intergroup differences. Our findings indicate that the UV-resistance seen in halophilic archaea can be attributed in part to a genomic strategy: high G + C content and the resulting bipyrimidine signature reduces the genomic photoreactivity.

  1. Development of O/W emulsions containing Euterpe oleracea extract and evaluation of photoprotective efficacy

    Directory of Open Access Journals (Sweden)

    Cláudia Cecilio Daher

    2014-09-01

    Full Text Available Euterpe oleraceaMart. is a palm tree popularly known as açai, which is primarily found in northern Brazil. The açai's fruits contain anthocyanins, a class of polyphenols to which antioxidant properties have been attributed. The aim of this work was to develop O/W sunscreens emulsions containing açai glycolic extract (AGE and to evaluate both their physical stability and photoprotective efficacy. Emulsions containing AGE and sunscreens were formulated using different types and concentrations of polymeric surfactant (acrylates/C 10-30 alkyl acrylate crosspolymer and sodium polyacrylate. The influence of two rheology modifiers (polyacrylamide (and C13-14/isoparaffin (and Laureth-7 and Carbomer on the stability was also investigated. Physical stability was evaluated by preliminary and accelerated studies. Emulsions with 1.0% sodium polyacrylate were stable and exhibited non-newtonian pseudoplastic behavior and thixotropy. Photoprotective efficacy was evaluated by in vivo Sun Protection Factor (SPF and determination of Protection Factor of UVA (PF-UVA. When AGE was added to the sunscreen emulsion, no significant increase in the in vivo SPF value was observed. The emulsion containing AGE showed PF-UVA = 14.97, 1.69 of the SPF/PF-UVA ratio and a critical wavelength value of 378 nm, and may therefore be considered a sunscreen with UVA and UVB protection.

  2. Platinum Activated IrO2/SnO2 Nanocatalysts and Their Electrode Structures for High Performance Proton Exchange Membrane Water Electrolysis

    DEFF Research Database (Denmark)

    Xu, Junyuan; Li, Qingfeng; Christensen, Erik

    2013-01-01

    In order to improve proton exchange membrane water electrolysis performance, anode catalyst and catalyst layer were examined in this work. SnO2 supported IrO2 nanocatalyst and its analogue with platinum enhancement were firstly synthesized for the oxygen evolution reaction. The effect of the intr...... improved due to the appropriate porosity and pore size distribution. The highest electrolyser performance of 1.63 V at 2 A cm-2 was achieved at 80 °C for optimized catalyst layers containing platinum activated IrO2/SnO2 catalyst....

  3. Improved performance in ionic exchange decalcifying processes using uniform resins; Mejoras de rendimiento en procesos de descalcificacion por intercambio ionico mediante el uso de resinas uniformes

    Energy Technology Data Exchange (ETDEWEB)

    Serrano Belmonte, J. LL.

    2000-07-01

    The physical characteristics of the resins used in ionic exchange water treatment equipment have a direct bearing on the performance of the treatment facilities as well as on the quality of the water and the effluent produced during regeneration. There are now resins available on the market which have grains of a uniform size as compared to conventional resins whose grain size in more uneven. This article describes the historical evolution of such resins for use in decalcifying equipment and the reasons for the improved performance that is obtained when resins of uniform grain size are used. The results of a practical experimental in currently operating real facilities are presented. (Author)

  4. High-Performance Anion-Exchange Chromatography Coupled with Pulsed Electrochemical Detection as a Powerful Tool to Evaluate Carbohydrates of Food Interest: Principles and Applications

    Directory of Open Access Journals (Sweden)

    Claudio Corradini

    2012-01-01

    Full Text Available Specific HPLC approaches are essential for carbohydrate characterization in food products. Carbohydrates are weak acids with pKa values in the range 12–14 and, consequently, at high pH can be transformed into oxyanions, and can be readily separated using highly efficient anion-exchange columns. Electrochemical detection in HPLC has been proven to be a powerful analytical technique for the determination of compounds containing electroactive groups; pulsed amperometric detection of carbohydrates is favourably performed by taking advantage of their electrocatalytic oxidation mechanism at a gold working electrode in a basic media. High-performance Anion Exchange Chromatography (HPAEC at high pH coupled with pulsed electrochemical detection (PED is one of the most useful techniques for carbohydrate determination either for routine monitoring or research application. This technique has been of a great impact on the analysis of oligo- and polysaccharides. The compatibility of electrochemical detection with gradient elution, coupled with the high selectivity of the anion-exchange stationary phases, allows mixtures of simple sugars, oligo- and polysaccharides to be separated with high resolution in a single run. A few reviews have been written on HPAEC-PED of carbohydrates of food interest in the last years. In this paper the recent developments in this field are examined.

  5. A survey on relationship between capital structure, free cash flow and diversification and firm performance of listed companies in Tehran Stock Exchange

    Directory of Open Access Journals (Sweden)

    Mohammad Khodaei Valahzaghard

    2014-10-01

    Full Text Available This paper presents an empirical investigation to study the effects of free cash flow, share diversification and capital structure on Tobin-Q in selected firms on Tehran Stock Exchange. The population of the survey includes 520 firms listed on this exchange until year 2012 and the survey uses a sample of 105 firms, randomly. The study uses the models originally developed by Palepu (1985 [Palepu, K. (1985. Diversification strategy, profit performance and the entropy measure. Strategic Management Journal, 6(3, 239-255.] to measure the effects of different factors on Tobin Q. The study has indicated that while capital structure and free cash flow influence positively on Tobin Q, diversification has maintained a negative and meaningful relationship with Tobin Q.

  6. Effect of ligand exchange of Cu2ZnSnS4 nanocrystals on the charge transport and photovoltaic performance of nanostructured depleted bulk heterojunction solar cell

    Science.gov (United States)

    Zhang, Zhuo-Xi; Zhou, Zheng-Ji; Bai, Bing; Liu, Ming-Hua; Zhou, Wen-Hui; Kou, Dong-Xing; Wu, Si-Xin

    2015-12-01

    Cu2ZnSnS4 (CZTS) nanocrystals combining the advantage of feasible solution-phase synthesis and processing are perceived as promising materials for application in efficient, low-cost photovoltaic technology. Herein, we have got surfactant-free CZTS nanocrystals by a novel ligand exchange method, and the obtained CZTS nanocrystals were deposited onto ZnO nanorod arrays to construct depleted bulk heterojunction solar cell. The all-inorganic CZTS nanocrystal solar cells demonstrated a remarkable improvement in J sc (from 8.14 to 13.97 mA/cm2) and power conversion efficiency (from 1.83 to 3.34 %) compared with surfactant-capped CZTS nanocrystals. Using surface photovoltage spectrum, the influence of ligand exchange of CZTS nanocrystals on the charge transport and photovoltaic performance of the nanostructured CZTS solar cells was discussed.

  7. Use of fluidized bed heat exchangers in heat pump systems for improved performance. Technical status report, September 1, 1977--November 31, 1977

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J C; Sarubbi, R G

    1977-11-01

    A York (Split System) heat pump 60,000 BTUH has been selected, and one unit delivered, for use in comparing its coefficient of performance with an identical system using fluidized bed heat exchangers. Construction has begun on a plenum which will supply air over a wide range of operating temperatures and at flow rates and pressures which are comparable to normal operating conditions. Means for monitoring air flow rates have been decided upon and a tentative selection of instrumentation sensor points have been selected. The existing heat exchanger design is being examined so that a better knowledge of the complete range of operating pressures, temperatures, flow rates and refrigerant quality can be obtained.

  8. Unraveling the Photoprotective Response of Lichenized and Free-Living Green Algae (Trebouxiophyceae, Chlorophyta) to Photochilling Stress.

    Science.gov (United States)

    Míguez, Fátima; Schiefelbein, Ulf; Karsten, Ulf; García-Plazaola, José I; Gustavs, Lydia

    2017-01-01

    Lichens and free-living terrestrial algae are widespread across many habitats and develop successfully in ecosystems where a cold winter limits survival. With the goal of comparing photoprotective responses in free-living and lichenized algae, the physiological responses to chilling and photochilling conditions were studied in three lichens and their isolated algal photobionts together as well as in a fourth free-living algal species. We specifically addressed the following questions: (i) Are there general patterns of acclimation in green algae under chilling and photochilling stresses? (ii) Do free-living algae exhibit a similar pattern of responses as their lichenized counterparts? (iii) Are these responses influenced by the selection pressure of environmental conditions or by the phylogenetic position of each species? To answer these questions, photosynthetic fluorescence measurements as well as pigment and low molecular weight carbohydrate pool analyses were performed under controlled laboratory conditions. In general, photochemical efficiency in all free-living algae decreased with increasing duration of the stress, while the majority of lichens maintained an unchanged photochemical activity. Nevertheless, these patterns cannot be generalized because the alga Trebouxia arboricola and the lichen Ramalina pollinaria (associated with Trebouxia photobionts) both showed a similar decrease in photochemical efficiency. In contrast, in the couple Elliptochloris bilobata-Baeomyces rufus, only the algal partner exhibited a broad physiological performance under stress. This study also highlights the importance of the xanthophyll cycle in response to the studied lichens and algae to photochilling stress, while the accumulation of sugars was not related to cold acclimation, except in the alga E. bilobata. The differences in response patterns detected among species can be mainly explained by their geographic origin, although the phylogenetic position should also be

  9. Unraveling the Photoprotective Response of Lichenized and Free-Living Green Algae (Trebouxiophyceae, Chlorophyta to Photochilling Stress

    Directory of Open Access Journals (Sweden)

    Fátima Míguez

    2017-07-01

    Full Text Available Lichens and free-living terrestrial algae are widespread across many habitats and develop successfully in ecosystems where a cold winter limits survival. With the goal of comparing photoprotective responses in free-living and lichenized algae, the physiological responses to chilling and photochilling conditions were studied in three lichens and their isolated algal photobionts together as well as in a fourth free-living algal species. We specifically addressed the following questions: (i Are there general patterns of acclimation in green algae under chilling and photochilling stresses? (ii Do free-living algae exhibit a similar pattern of responses as their lichenized counterparts? (iii Are these responses influenced by the selection pressure of environmental conditions or by the phylogenetic position of each species? To answer these questions, photosynthetic fluorescence measurements as well as pigment and low molecular weight carbohydrate pool analyses were performed under controlled laboratory conditions. In general, photochemical efficiency in all free-living algae decreased with increasing duration of the stress, while the majority of lichens maintained an unchanged photochemical activity. Nevertheless, these patterns cannot be generalized because the alga Trebouxia arboricola and the lichen Ramalina pollinaria (associated with Trebouxia photobionts both showed a similar decrease in photochemical efficiency. In contrast, in the couple Elliptochloris bilobata-Baeomyces rufus, only the algal partner exhibited a broad physiological performance under stress. This study also highlights the importance of the xanthophyll cycle in response to the studied lichens and algae to photochilling stress, while the accumulation of sugars was not related to cold acclimation, except in the alga E. bilobata. The differences in response patterns detected among species can be mainly explained by their geographic origin, although the phylogenetic position should

  10. Photoprotection in a purple phototrophic bacterium mediated by oxygen-dependent alteration of carotenoid excited-state properties

    Czech Academy of Sciences Publication Activity Database

    Šlouf, V.; Chábera, P.; Olsen, J.D.; Martin, E.C.; Qian, P.; Hunter, C.N.; Polívka, Tomáš

    2012-01-01

    Roč. 109, č. 22 (2012), s. 8570-8575 ISSN 0027-8424 Institutional research plan: CEZ:AV0Z50510513 Keywords : charge-transfer state * photoprotection * purple bacteria * photosynthesis Subject RIV: BO - Biophysics Impact factor: 9.737, year: 2012

  11. PERFORMANCE EVALUATION OF PROPERTY AND REAL ESTATE COMPANIES LISTED ON INDONESIA STOCK EXCHANGE USING DATA ENVELOPMENT ANALYSIS

    Directory of Open Access Journals (Sweden)

    Tessa V. Soetanto

    2014-01-01

    Full Text Available   This paper aimed to evaluate perfomance of property and real estate companies listed in Indonesia Stock Exchange using the DEA method. Samples were 23 companies listed from 2009–2012. Results showed that some companies are relatively efficient each year. However, only one company consistently had technical efficiency equal to 1. The main cause of inefficiency from 2009–2011 was scale inefficiency while inefficiency happened in 2012 was pure technical inefficiency. Overall the companies operate efficiently un-der constant returns to scale is showing an increase from 17.39%–39.13%.

  12. Performance of a UV/hydrogen peroxide/ion exchange treatment plant on groundwater leaching from mixed waste contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Kelso, W.J. [Parsons Engineering Science, Inc., Denver, CO (United States); Cirillo, J.R.; Burmeister, M.C. [Rocky Mountain Remediation, Golden, CO (United States)

    1995-12-31

    This paper summarizes the operation and results of a groundwater treatment plant at the Rocky Flats Environmental Technology Site. The principal contaminants are volatile organic compounds (VOCs), heavy metals, and radionuclides. The treatment plant uses ultraviolet light and hydrogen peroxide for destruction of VOCs, and ion exchange for removal of dissolved solids, metals, and uranium. During three years of operation, the treatment plant has achieved typical removal efficiencies of 99% for VOCs, 80% for total dissolved solids, and 98% for radionuclides. Contaminant influent ranges and percent removal are listed.

  13. [Photoprotection, melasma and quality of life in pregnant women].

    Science.gov (United States)

    Purim, Kátia Sheylla Malta; Avelar, Maria Fernanda de Santana

    2012-05-01

    To evaluate habits of sun exposure and sun protection of pregnant women in a public hospital, to assess orientation about photo protection during the prenatal care, and to detect the presence of melasma and its impact on their quality of life. A descriptive cross sectional study conducted among women of 18 years old and older, after delivery, who participated in a program of prenatal care in the South Region of Brazil. The sample was non-probabilistic by convenience. Data collection occurred from July to August 2011 through direct interview using a structured questionnaire to obtain personal information and photo protection habits during pregnancy, skin assessment and photographic record of lesions through informed consent. The skin was classified per Fitzpatrick's phototypes and the melasma was diagnosed clinically. In the patients with melasma, the MELASQoL-PB version was applied. The analysis was performed using Statistica, version 8.0, and the significance level of pmelasma. The average score MELASQol-PB (25) showed a negative impact on quality of life of these patients. In these women, sun exposure occurred at inappropriate times, without proper guidance and without the use of an effective sunscreen. The mothers with melasma complained about the appearance of their skin, frustration and embarrassment.

  14. Addition of sulfonated silicon dioxide on an anode catalyst layer to improve the performance of a self-humidifying proton exchange membrane fuel cell

    Science.gov (United States)

    Lin, Chien-Liang; Hsu, Shih-Chieh; Ho, Wei-Yu

    2016-03-01

    Sulfonated SiO2 was added on an anode catalyst layer to manufacture a hygroscopic electrode for self-humidifying proton exchange membrane fuel cells (PEMFCs). The inherent humidity of a proton exchange membrane (PEM) determines the electrical performance of PEMFCs. To maintain the high moisture content of the PEM, self-humidifying PEMFCs can use the water produced by the fuel cell reaction and, thus, do not require external humidification. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and water contact angle measurement tests were performed to characterize the structures and properties of sulfonated SiO2 and the related electrodes, and the electric current and voltage (I-V) performance curve tests for the fuel cells were conducted under differing gas humidification conditions. When 0.01mg/cm2 of sulfonated SiO2 was added, the electrical performance of the fuel cells (50∘C) increased 29% and 59% when the fuel cell reaction gases were humidified at 70∘C and 50∘C, respectively.

  15. Preparation of an ion-exchangeable polymer bead wrapped with bilayer membrane structures for high performance liquid chromatography.

    Science.gov (United States)

    Haratake, Mamoru; Hidaka, Shuko; Ono, Masahiro; Nakayama, Morio

    2007-04-18

    We synthesized a chromatographic packing material that has a non-covalently attached dihexadecyl phosphate (DHP) bilayer membrane structure on a CA08S, a nonporous-type cationic polymer bead with a diameter ranging from 11 to 14 microm. Confocal fluorescence microscopic and differential scanning calorimetric analyses of the DHP-CA08S complex revealed that the DHP bilayer membrane structures were formed on the surface of the CA08S polymer beads. When the functionality of the DHP-CA08S complex was evaluated in the ion-exchange HPLC of proteins, the retention behavior of the proteins on the DHP-CA08S complex column totally mirrored the anionic property of the DHP bilayer membrane surface, not the cationic property of the CA08S bead. Methylene blue (MB) was eluted from the DHP-CA08S complex column in the isocratic elution mode, but not at all from a CK08S column, a styrene-divinylbenzene based cation-exchange polymer. When the column temperature was elevated from 50 to 60 degrees C, the peak shape of MB on the DHP-CA08S complex column became fairly sharp without a change in its peak area, which mirrored the characteristic phase transition of the DHP bilayer membrane formed on the DHP-CA08S complex.

  16. An Investigation into the Effect of Cation-exchange on the Adsorption Performance of Indium-based Sodalite-ZMOF

    KAUST Repository

    Samin, Umer A.

    2016-04-13

    There is a pressing need for advanced solid-state materials that can be implemented in industrial gas separation processes to achieve separations with a significantly reduced energy input compared to what is typically required from current technologies. Although certain porous materials like zeolites bear some commercial significance for gas separation; their inherent lack of tunability limits the extent to which these materials may be exploited in industry. Zeolite-like Metal-Organic Frameworks (ZMOFs) are a sub-class of Metal-Organic Framework materials (MOFs) that show a structural semblance to zeolites while possessing the tunability advantages of MOF materials. ZMOFs which are topologically similar to certain zeolites can be functionalised and tuned in numerous ways to improve their gas separation properties. In this work, indium-based sod-ZMOF was tuned by cation-exchange and then characterised by different experimental tools such as single-crystal x-ray diffraction, elemental analysis and gas adsorption. It was found that various parameters like the choice of cation, the concentration of salt solution and the choice of solvent had a significant bearing on the cation-exchange of sod-ZMOF and its subsequent adsorption properties.

  17. Use of anion-exchange membrane extraction for the high-performance liquid chromatographic analysis of mustard seed glucosinolates.

    Science.gov (United States)

    Szmigielska, A M; Schoenau, J J

    2000-11-01

    A new one-step extraction using anion-exchange membranes for the HPLC determination of glucosinolates in mustard seeds is reported. The exchange of glucosinolates on the membranes was studied using sinigrin in solutions and sinigrin added as an internal standard to seeds of yellow mustard. By varying time of extraction, membrane size, and sample size, the optimal conditions for maximum glucosinolate recovery were determined and the following procedure was adopted: 0.2 g of ground mustard seeds are heated in 20 mL of boiling water for 5 min. After cooling, samples are transferred to plastic centrifuge tubes, 9-cm(2) membranes are added, and suspensions are shaken on a mechanical shaker for 2.5 h. Glucosinolates are then eluted from the membranes with 25 mL of 1 N KCl by shaking again for 2.5 h. Using this procedure, the sinigrin extraction from solutions and from mustard seeds was linear with 80% recovery. Seeds of yellow, brown, oriental, and Indian mustard were analyzed by this procedure; excellent reproducibility, with coefficients of variation in the range 1.0-4.3% were obtained. This method offers a simple and inexpensive alternative to complicated and tedious procedures for glucosinolate isolation/purification required for chromatographic determinations.

  18. Integrating dynamic fuzzy C-means, data envelopment analysis and artificial neural network to online prediction performance of companies in stock exchange

    Science.gov (United States)

    Jahangoshai Rezaee, Mustafa; Jozmaleki, Mehrdad; Valipour, Mahsa

    2018-01-01

    One of the main features to invest in stock exchange companies is their financial performance. On the other hand, conventional evaluation methods such as data envelopment analysis are not only a retrospective process, but are also a process, which are incomplete and ineffective approaches to evaluate the companies in the future. To remove this problem, it is required to plan an expert system for evaluating organizations when the online data are received from stock exchange market. This paper deals with an approach for predicting the online financial performance of companies when data are received in different time's intervals. The proposed approach is based on integrating fuzzy C-means (FCM), data envelopment analysis (DEA) and artificial neural network (ANN). The classical FCM method is unable to update the number of clusters and their members when the data are changed or the new data are received. Hence, this method is developed in order to make dynamic features for the number of clusters and clusters members in classical FCM. Then, DEA is used to evaluate DMUs by using financial ratios to provide targets in neural network. Finally, the designed network is trained and prepared for predicting companies' future performance. The data on Tehran Stock Market companies for six consecutive years (2007-2012) are used to show the abilities of the proposed approach.

  19. Influence of heat and moisture exchanger use on measurements performed with manovacuometer and respirometer in healthy adults.

    Science.gov (United States)

    Lucato, Jeanette Janaina Jaber; Nogueira da Cunha, Thiago Marraccini; Rocha, Sara Solange Oliveira Costa; Palmieri de Carvalho, Fernanda Maria; Botega, Daniele Cristina; Torquato, Jamili Anbar; Gimenes, Ana Cristina; Righetti, Renato Fraga

    2015-01-01

    The use of evaluation tools such as the manovacuometer and respirometer is frequent and disinfection is usually limited to the external surfaces, which is insufficient and raises concerns because of the potential spread of infectious diseases. Hydrophobic heat and moisture exchangers (HME) are used in mechanical ventilation and have microbiological filters, which can possibly reduce contamination, increasing the safety of related procedures. It is unknown, however, if the addition of an exchanger affects the measurements obtained. Aim of this study was to verify if the use of an HME interferes in maximal inspiratory and expiratory pressures assessed using the manovacuometer and vital capacity evaluated using the respirometer in healthy adults. A controlled transversal trial was carried out. Twenty healthy young adults were included in the study. Vital capacity by respirometer and, maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were assessed with and without the use of HME. No significant difference was found between the values pre and post HME use in vital capacity measurements: (3878.8 ± 202.2 mL vs. 3925.5 ± 206.0 mL, p = 0.116) and the respiratory muscle strength measurements: MIP (-99.0 ± 8.9 vs -95.5 ± 9.0 cm H2O, p = 0.149) and MEP (92.5 ± 7.5 vs 92.5 ± 7.7 cm H2O, p = 1.0) respectively. We conclude that the use of HME does not modify the lung volumes or respiratory muscle strength, and can be used in order to reduce the occurrence of pulmonary infection.

  20. STOCK PERFORMANCE ANALYSIS OF LISTED ENTITIES AT THE BUCHAREST STOCK EXCHANGE. CASE STUDY ON THE ENERGY AND RELATED UTILITIES SECTOR COMPANIES

    Directory of Open Access Journals (Sweden)

    Ioana Anghel

    2016-12-01

    Full Text Available Financial performance, as a multi-criteria economic category, constitutes a current topic broadly investigated by authors and experts in finance, financial management, accounting, evaluation and general management. In this ever more competitive capital market, because investors are increasingly better informed, it becomes essential for a company to know and periodically evaluate its stock performance in order to compare it at economic branch level. This present research study analyses six companies that activate in the energy and related utilities sector, listed at the Bucharest Stock Exchange, between 2004 and 2015, with the aim of identifying branch similarities regarding the evolution of the key stock growth ratios and indicators used in stock performance analysis. Furthermore, the authors deemed appropriate to correlate their results with the evolution of the main rates of return of the same companies

  1. Antioxidative defense and photoprotection in Pinus halepensis induced by Mediterranean conditions and ozone exposure.

    Science.gov (United States)

    Alonso, R; Elvira, S; Castillo, F J; Gimeno, B S

    1999-12-01

    Pigment levels and antioxidative stress-related metabolites were determined over a period of two years in Pinus halepensis to characterize the response of some plant protective processes to both environmental stresses and 03 exposure. Two-year-old-Aleppo pine seedlings were grown in open-top chambers under optimal nutrient and water conditions and exposed to different 03 levels: charcoal filtered air, non-filtered air and nonfiltered air plus 40 ppb O3 10 h/day. In summer an activation of photoprotective systems was observed since a decrease in chlorophyll levels, an increase in the carotenoid/chlorophyll ratio and SOD activation were recorded. Interestingly, the SOD activity in Pinus halepensis was highly related to low-molecular weight compounds and this relationship increased with needle age. Ozone exposure induced alterations in the activity of some antioxidant enzymes along with reductions in pigment concentrations and an activation of the xanthophyll cycle.

  2. Wavelength-selective cleavage of photoprotecting groups: strategies and applications in dynamic systems.

    Science.gov (United States)

    Hansen, Mickel J; Velema, Willem A; Lerch, Michael M; Szymanski, Wiktor; Feringa, Ben L

    2015-06-07

    Photocleavable protecting groups (PPGs) are extensively used in chemical and biological sciences. In their application, advantage is taken of using light as an external, non-invasive stimulus, which can be delivered with very high spatiotemporal precision. More recently, orthogonally addressing multiple PPGs, in a single system and with different wavelengths of light, has been explored. This approach allows one to independently control multiple functionalities in an external, non-invasive fashion. In this tutorial review, we discuss the design principles for dynamic systems involving wavelength-selective deprotection, focusing on the choice and optimization of PPGs, synthetic methods for their introduction and strategies for combining multiple PPGs into one system. Finally, we illustrate the design principles with representative examples, aiming at providing the reader with an instructive overview on how the wavelength-selective cleavage of photoprotecting groups can be applied in materials science, organic synthesis and biological systems.

  3. UVA-UVB photoprotective activity of topical formulations containing Morinda citrifolia extract.

    Science.gov (United States)

    Serafini, Mairim Russo; Detoni, Cassia Britto; Menezes, Paula dos Passos; Pereira Filho, Rose Nely; Fortes, Vanessa Silveira; Vieira, Maria José Fonseca; Guterres, Sílvia Stanisçuaski; Cavalcanti de Albuquerque Junior, Ricardo Luiz; Araújo, Adriano Antunes de Souza

    2014-01-01

    Exposure to solar radiation, particularly its ultraviolet (UV) component, has a variety of harmful effects on human health. Some of these effects include sunburn cell formations, basal and squamous cell cancers, melanoma, cataracts, photoaging of the skin, and immune suppression. The beneficial photoprotective effects of topical formulations with the extract, Morinda citrifolia, have not been investigated. This present study aims to investigate the potential benefits of M. citrifolia topical application on the dorsal skin of mice, exposed to UVA-UVB light. Using 7 days of treatment, [before (baseline values) and 20 h after UV exposure], the thickness, skin barrier damage (TEWL), erythema, and histological alterations were evaluated. The results showed that the formulations containing the extract protected the skin against UV-induced damage.

  4. Comparison of plasma exchange performances between Spectra Optia and COBE Spectra apheresis systems in repeated procedures considering variability and using specific statistical models.

    Science.gov (United States)

    Hequet, O; Stocco, V; Assari, S; Drillat, P; Le, Q H; Kassir, A; Rigal, D; Bouzgarrou, R

    2014-08-01

    Repeated therapeutic plasma exchange (TPE) procedures using centrifugation techniques became a standard therapy in some diseases. As the new device Spectra Optia (SPO; Terumo BCT) was available, we studied its performances in repeated procedures in 20 patients in three apheresis units. First we analysed the performance results obtained by SPO. Second we compared the performances of the SPO device to a standard device, COBE Spectra (CSP; Terumo BCT) in the same patients using statistical method of mixed effects linear regression that considers variability between patients, centres and apheresis procedures. The performances analysed were classified according to plasma removal performances and their consequences on patients whose blood disturbances were assessed. Primary outcome was plasma removal efficiency (PRE) and PRE-anticoagulant corrected which was a more accurate parameter. Secondary outcomes corresponded to the volume of ACD-A consumed, platelets content in waste bag, procedure duration and status of coagulation system observed after TPE sessions. Before comparing the performances of both devices we compared the plasma volumes (PVs) processed in both techniques which showed that the PVs processed in SPO procedures were lower than in CSP procedures. In these conditions the statistical analysis revealed similar performances in both apheresis devices in PRE (p = ns) but better performances with SPO when considering higher PRE corrected by anticoagulant volume used (p technical complications occurred during and after SPO and CSP. This study demonstrated that the Spectra Optia device is an alternative device to today's standard, the COBE Spectra device. Copyright © 2014. Published by Elsevier Ltd.

  5. Trihydroxybenzoic acid glucoside as a global skin color modulator and photo-protectant

    Directory of Open Access Journals (Sweden)

    Chajra H

    2015-11-01

    Full Text Available Hanane Chajra,1 Gérard Redziniak,2 Daniel Auriol,3 Kuno Schweikert,1 Fabrice Lefevre1 1Induchem AG, Volkestwil, Switzerland; 2Cosmetic Invention, Antony, 3Libragen SA, Toulouse, France Background: 3,4,5-Trihydroxybenzoic acid glucoside (THBG, a molecule produced by an original biocatalysis-based technology, was assessed in this study with respect to its skin photoprotective capacity and its skin color control property on Asian-type skin at a clinical level and on skin explant culture models. Methods: The double-blinded clinical study was done in comparison to a vehicle by the determination of objective color parameters thanks to recognized quantitative and qualitative analysis tools, including Chroma-Meter, VISIA-CR™, and SIAscope™. Determination of L* (brightness, a* and b* (green–red and blue–yellow chromaticity coordinates, individual typology angle, and C* (chroma and h* (hue angle parameters using a Chroma-Meter demonstrated that THBG is able to modify skin color while quantification of ultraviolet (UV spots by VISIA-CR™ confirmed its photoprotective effect. The mechanism of action of THBG molecule was determined using explant skin culture model coupled to histological analysis (epidermis melanin content staining. Results: We have demonstrated that THBG was able to modulate significantly several critical parameters involved in skin color control such as L* (brightness, a* (redness, individual typology angle (pigmentation, and hue angle (yellowness in this study, whereas no modification occurs on b* and C* parameters. We have demonstrated using histological staining that THBG decrease epidermis melanin content under unirradiated and irradiated condition. We also confirmed that THBG molecule is not a sunscreen agent. Conclusion: This study demonstrated that THBG controls skin tone via the inhibition of melanin synthesis as well as the modulation of skin brightness, yellowness, and redness. Keywords: skin color, UV spots

  6. Photoprotective responses in a brown macroalgae Cystoseira tamariscifolia to increases in CO2 and temperature.

    Science.gov (United States)

    Celis-Plá, Paula S M; Martínez, Brezo; Korbee, Nathalie; Hall-Spencer, Jason M; Figueroa, Félix L

    2017-09-01

    Global warming and ocean acidification are increasingly affecting coastal ecosystems, with impacts that vary regionally depending upon local biogeography. Ocean acidification drives shifts in seaweed community dominance that depend on interactions with other factors such as light and nutrients. In this study, we investigated the photophysiological responses in the brown macroalgae species Cystoseira tamariscifolia (Hudson) Papenfuss with important structural role in the coastal Mediterranean communities. These algae were collected in the Cabo de Gata-Nijar Natural Park in ultraoligotrophic waters (algae exposed under high irradiance and less nutrient conditions) vs. those collected in the La Araña beach in oligotrophic waters (algae exposed at middle nutrient and irradiance conditions) in the Mediterranean Sea. They were incubated in mesocosms, under two levels of CO2; ambient (400-500 ppm) and high CO2 (1200-1300 ppm), combined with two temperatures (ambient temperature; 20 °C and ambient temperature + 4 °C; 24 °C) and the same nutrient conditions of the waters of the origin of macroalgae. Thalli from two sites on the Spanish Mediterranean coast were significantly affected by increases in pCO2 and temperature. The carotenoids (fucoxanthin, violaxanthin and β-carotene) contents were higher in algae from oligotrophic than that from ultraoligotrophic water, i.e., algae collected under higher nutrient conditions respect to less conditions, increase photoprotective pigments content. Thalli from both locations upregulated photosynthesis (as Fv/Fm) at increased pCO2 levels. Our study shows that ongoing ocean acidification and warming can increase photoprotection and photosynthesis in intertidal macroalgae. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Mechanisms of Photoaging and Cutaneous Photocarcinogenesis, and Photoprotective Strategies with Phytochemicals

    Directory of Open Access Journals (Sweden)

    Ricardo Bosch

    2015-03-01

    Full Text Available Photoaging and photocarcinogenesis are primarily due to solar ultraviolet (UV radiation, which alters DNA, cellular antioxidant balance, signal transduction pathways, immunology, and the extracellular matrix (ECM. The DNA alterations include UV radiation induced thymine-thymine dimers and loss of tumor suppressor gene p53. UV radiation reduces cellular antioxidant status by generating reactive oxygen species (ROS, and the resultant oxidative stress alters signal transduction pathways such as the mitogen-activated protein kinase (MAPK, the nuclear factor-kappa beta (NF-κB/p65, the janus kinase (JAK, signal transduction and activation of transcription (STAT and the nuclear factor erythroid 2-related factor 2 (Nrf2. UV radiation induces pro-inflammatory genes and causes immunosuppression by depleting the number and activity of the epidermal Langerhans cells. Further, UV radiation remodels the ECM by increasing matrixmetalloproteinases (MMP and reducing structural collagen and elastin. The photoprotective strategies to prevent/treat photoaging and photocarcinogenesis include oral or topical agents that act as sunscreens or counteract the effects of UV radiation on DNA, cellular antioxidant balance, signal transduction pathways, immunology and the ECM. Many of these agents are phytochemical derivatives and include polyphenols and non-polyphenols. The flavonoids are polyphenols and include catechins, isoflavones, proanthocyanidins, and anthocyanins, whereas the non-flavonoids comprise mono phenolic acids and stilbenes. The natural sources of polyphenols include tea, cocoa, grape/wine, soy, pomegranate, and Polypodium leucotomos. The non-phenolic phytochemicals include carotenoids, caffeine and sulphoraphance (SFN. In addition, there are other phytochemical derivatives or whole extracts such as baicalin, flavangenol, raspberry extract, and Photomorphe umbellata with photoprotective activity against UVB radiation, and thereby carcinogenesis.

  8. Photoprotective potential in some medicinal plants used to treat skin diseases in Sri Lanka.

    Science.gov (United States)

    Napagoda, Mayuri Tharanga; Malkanthi, Benthota Malavi Arachchige Shamila; Abayawardana, Subasinghe Appuhamillage Kaumudi; Qader, Mohomed Mallique; Jayasinghe, Lalith

    2016-11-24

    The constant exposure to solar ultraviolet radiation (UV) has a variety of harmful effects on human health. Although synthetic sunscreen products have been introduced as a preventive/therapeutic strategy, with the realization of their adverse side effects, the recent trend is to search for human friendly alternative formulations especially of plant origin. Therefore, the present study focuses on evaluation of photoprotective activity of aqueous extracts (1 mg/ml) of eleven medicinal plants in Sri Lanka that have been widely employed in traditional medicine as treatment options for various skin diseases and to improve the complexion. For the determination of UV filtering potential of the extracts, UV absorption was measured and the sun protection factor (SPF) was calculated according the Mansur equation. The antioxidant activity was evaluated by DPPH and ABTS assays. Among the extracts, Atalantia ceylanica, Hibiscus furcatus, Leucas zeylanica, Mollugo cerviana, Olax zeylanica and Ophiorrhiza mungos have displayed SPF value ≥ 25, which are even higher than two commercial photoprotective creams used as reference compounds. L. zeylanica and O. mungos have displayed a high UV absorbance in 260-350 nm range indicating their potential of being broad spectrum sunscreens. In addition, the extract of O. mungos was found to be photostable, without any significant reduction in the SPF after exposure to direct solar radiation for 21 days. DPPH assay and the ABTS assay revealed that the extracts possess high antioxidant activity. The results of the present study suggest that the presence of secondary metabolites with antioxidant property could be responsible for the high UV absorbance. Our findings would offer an exciting avenue for further research towards the development of herbal cosmetics.

  9. Photoprotection of Buddleja cordata extract against UVB-induced skin damage in SKH-1 hairless mice.

    Science.gov (United States)

    Avila Acevedo, José Guillermo; Espinosa González, Adriana Montserrat; De Maria y Campos, Diana Matamoros; Benitez Flores, José del Carmen; Hernández Delgado, Tzasna; Flores Maya, Saul; Campos Contreras, Jorge; Muñoz López, José Luis; García Bores, Ana María

    2014-08-03

    In recent years, there has been considerable interest in using botanical agents to prevent skin damage resulting from solar UV-irradiation. Buddleja cordata is a plant that is known as "tepozan". Some people in Mexico use the leaves of this plant to treat tumours, abscesses, sores and burns. The purpose of this study is to investigate the photoprotective properties of Buddleja cordata methanolic extract (BCME) against UVB-induced skin damage in SKH-1 hairless mice at the macroscopic and histological levels. BCME was characterised to determine its spectroscopic, chromatographic and antioxidant (DPPH, superoxide and hydroxyl radicals) properties. To conduct the photoprotection studies, BCME was applied topically to the skin of SKH-1 mice before acute exposure to UVB for 10 minutes. The murine skin samples were used for macroscopic and histological studies to assess tissue damage. Penetration of active components of BCME into stratum corneum on the dorsal area of mice was investigated in vivo by the tape stripping method. Moreover, genotoxicity of BCME was evaluated in a Vicia faba cell root micronucleus model. BCME displayed absorbance over the entire UVB spectrum, and its principal components included verbascoside and linarin. BCME exhibited antioxidant activity and significantly scavenged hydroxyl radicals. BCME reduced erythema, sunburn cell production, vessel congestion and epidermal thickening of UVB irradiated mouse skin. BCME penetrate the skin of mice. BCME did not exhibit genotoxic activity in the micronucleus test. The topical administration of BCME protected against acute UVB-induced damage in mouse SKH-1 skin, and our results suggest that BCME may potentially prevent photodamage.

  10. Verification of the Performance of a Vertical Ground Heat Exchanger Applied to a Test House in Melbourne, Australia

    Directory of Open Access Journals (Sweden)

    Koon Beng Ooi

    2017-10-01

    Full Text Available The ground heat exchanger is traditionally used as a heat source or sink for the heat pump that raises the temperature of water to about 50 °C to heat houses. However, in winter, the heating thermostat (temperature at which heating begins in the Australian Nationwide House Energy Rating Scheme (NatHERS is only 20 °C during daytime and 15 °C at night. In South-East Melbourne, the temperature at the bottom of a 50-meter-deep borehole has been recorded with an Emerson™ recorder at 17 °C. Melbourne has an annual average temperature of 15 °C, so the ground temperature increases by 2 °C per 50-m depth. A linear projection gives 23 °C at 200-m of depth, and as the average undisturbed temperature of the ground for a 400-m-deep vertical ground heat exchanger (VGHE. This study, by simulation and experimentation, aims to verify that the circulation of water in the VGHE’s U-tube to low-temperature radiators (LTRs could heat a house to thermal comfort. A literature review is included in the introduction. A simulation, using a model of a 60-m2 experimental house, shows that the daytime circulation of water in this VGHE/LTR-on-opposite-walls system during the 8-month cold half of the year, heats the indoors to NatHERS settings. Simulation for the cold half shows that this VGHE-LTR system could cool the indoors. Instead, a fan creating a cooling sensation of up to 4 °C is used so that the VGHE is available for the regeneration of heat extracted from the ground during the cold portion. Simulations for this hot portion show that a 3.4-m2 flat plate solar collector can collect more than twice the heat extracted from the ground in the cold portion. Thus, it can thus replenish the ground heat extracted for houses double the size of this 60-m2 experimental house. Therefore, ground heat is sustainable for family-size homes. Since no heat pump is used, the cost of VGHE-LTR systems could be comparable to systems using the ground source heat pump. Water

  11. Performance of Generating Plant: Managing the Changes. Part 1: International availability data exchange for thermal generating plant

    Energy Technology Data Exchange (ETDEWEB)

    Stallard, G.S.; Deschaine, R. [Black and Veatch (United States)

    2008-05-15

    The WEC Committee on the Performance of Generating Plant (PGP) has been collecting and analysing power plant performance statistics worldwide for more than 30 years and has produced regular reports, which include examples of advanced techniques and methods for improving power plant performance through benchmarking. A series of reports from the various working groups was issued in 2008. This reference presents the results of Working Group 1 (WG1). WG1's primary focus is to analyse the best ways to measure, evaluate, and apply power plant performance and availability data to promote plant performance improvements worldwide. The paper explores the specific work activities of 2004-2007 to extend traditional analysis and benchmarking frameworks. It is divided into two major topics: Overview of current electric supply industry issues/trends; and, Technical Methods/Tools to evaluate performance in today's ESI.

  12. Carbon supported Ag nanoparticles as high performance cathode catalyst for H2/O2 anion exchange membrane fuel cell

    Science.gov (United States)

    Xin, Le; Zhang, Zhiyong; Wang, Zhichao; Qi, Ji; Li, Wenzhen

    2013-01-01

    A solution phase-based nanocapsule method was successfully developed to synthesize non-platinum metal catalyst—carbon supported Ag nanoparticles (Ag/C). XRD patterns and TEM image show Ag nanoparticles with a small average size (5.4 nm) and narrow size distribution (2–9 nm) are uniformly dispersed on the carbon black Vulcan XC-72 support. The intrinsic activity and pathway of oxygen reduction reaction (ORR) on the Ag/C and commercial Pt/C were investigated using rotating ring disk electrode (RRDE) tests at room temperature. The results confirmed that the 4-electron pathway of ORR proceeds on small Ag nanoparticles, and showed comparable ORR activities on the self-prepared Ag/C and a commercial Pt/C. A single H2-O2 anion exchange membrane fuel cell (AEMFC) with the Ag/C cathode catalyst exhibited an open circuit potential of 0.98 V and a peak power density of 190 mW/cm2 at 80°C. PMID:24790944

  13. Effect of "bridge" on the performance of organic-inorganic crosslinked hybrid proton exchange membranes via KH550

    Science.gov (United States)

    Han, Hailan; Li, Hai Qiang; Liu, Meiyu; Xu, Lishuang; Xu, Jingmei; Wang, Shuang; Ni, Hongzhe; Wang, Zhe

    2017-02-01

    A series of novel organic-inorganic crosslinked hybrid proton exchange membranes were prepared using sulfonated poly(arylene ether ketone sulfone) polymers containing carboxyl groups (C-SPAEKS), (3-aminopropyl)-triethoxysilane (KH550), and tetraethoxysilane (TEOS). KH550 acted as a "bridge" after reacting with carboxyl and sulfonic groups of C-SPAEKS to form covalent and ionic crosslinked structure between the C-SPAEKS and SiO2 phase. The crosslinked hybrid membranes (C-SPAEKS/K-SiO2) were characterized by FT-IR spectroscopy, TGA, and electrochemistry, etc. The thermal stability, mechanical properties and proton conductivity of the crosslinked hybrid membranes were improved by the presence of both crosslinked structure and inorganic phase. The proton conductivity of C-SPAEKS/K-SiO2-8 was recorded as 0.110 S cm-1, higher than that of Nafion® (0.028 S cm-1) at 120 °C. Moreover, the methanol permeability of the C-SPAEKS/K-SiO2-8 was measured as 3.86 × 10-7 cm2 s-1, much lower than that of Nafion® 117 membranes (29.4 × 10-7 cm2 s-1) at 25 °C.

  14. Coupling ion-exchangers with inexpensive activated carbon fiber electrodes to enhance the performance of capacitive deionization cells for domestic wastewater desalination.

    Science.gov (United States)

    Liang, Peng; Yuan, Lulu; Yang, Xufei; Zhou, Shaoji; Huang, Xia

    2013-05-01

    A capacitive deionization (CDI) cell was built with electrodes made of an inexpensive commercial activated carbon fiber (ACF), and then modified by incorporating ion-exchangers into the cell compartment. Three modified CDI designs were tested: MCDI - a CDI with electrodes covered by ion-exchange membranes (IEMs) of the same polarity, FCDI - a CDI with electrodes covered by ion-exchange felts (IEFs), and R-MCDI - an MCDI with cell chamber packed with ion-exchange resin (IER) granules. The cell was operated in the batch reactor mode with an initial salt concentration of 1000 mg/L NaCl, a typical level of domestic wastewater. The desalination tests involved investigations of two consecutive operation stages of CDIs: electrical adsorption (at an applied voltage of 1.2 V) and desorption [including short circuit (SC) desorption and discharge (DC) desorption]. The R-MCDI showed the highest electric adsorption as measured in the present study by desalination rate [670 ± 20 mg/(L h)] and salt removal efficiency (90 ± 1%) at 60 min, followed by the MCDI [440 ± 15 mg/(L h) and 60 ± 2%, respectively]. The superior desalination performance of the R-MCDI over other designs was also affirmed by its highest charge efficiency (110 ± 7%) and fastest desorption rates at both the SC [1960 ± 15 mg/(L·h)] and DC [3000 ± 20 mg/(L·h)] modes. The desalination rate and salt removal efficiency of the R-MCDI increased from ∼270 mg/(L h) and 83% to ∼650 mg/(L h) and 98% respectively when the applied voltage increased from 0.6 V to 1.4 V, while decreased slightly when lowering the salt water flow rate that fed into the cell. The packing of IER granules in the R-MCDI provided additional surface area for ions transfer; meanwhile, according to the results of electrochemical impedance spectroscopy (EIS) analysis, it substantially lower down the R-MCDI's ohmic resistance, resulting in improved desalination performance. Copyright © 2013 Elsevier Ltd. All

  15. UJI PERFORMANSI DESAIN TERINTEGRASI TUNGKU BIOMASSA DAN PENUKAR PANAS (Performance Test of The Integrated Design of Biomass Furnace and Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Muhammad Tahir

    2013-08-01

    Full Text Available A series testing of the integrated design of biomass furnace and heat exchanger was conducted to see the performance using methods such as the effectivenes-number of transfer unit (e-NTU,  the efficiency as a function of Fin Analogy Number (h(Fa and the log-mean temperature difference (LMTD. The biomass furnace as a plant to generated heat produced value of energy 25,600W with the burning rated of corncob 7.03 kg/hour. The calculation of amount of heat transfer to the cold fluid in the tubes as function of fluid characteristic, mass rated of dry air in a longitudinal section was 11,285W. The effectivenes as the ratio of actual heat transfered to the absolute maximum heat that can be transferred in a heat exchanger was 0.90. The efficiency of heat exchanger as a clear measurement of performance system was 0.78. The efficiency as a function of fin analogy number, employed several variable as it function; such as the product of UA, minimum heat capacity rate (Cmin and the capacity ratio (Cr. Another performance showed by correction factor with value of 0.5 indicated that the heat exchanger was not a pure of counter-flow but made of cross-flow in the single segmental baffle with turbulances pattern (Re: 8.524 > 6.000. Keywords: Heat exchanger, biomass furnace, effectivenes, efficiency, performance test   ABSTRAK Serangkaian pengujian terhadap desain terintegrasi tungku biomassa dan penukar panas telah dilakukan untuk melihat performansinya menggunakan metode efektifitas-NTU (e-NTU, efisiensi sebagai fungsi dari fin analogy number (h(Fa dan beda temperatur rata-rata logaritmik (LMTD. Tungku biomassa sebagai pembangkit panas menghasilkan energi senilai 25.600W dengan laju pembakaran tongkol jagung 7.03 kg/jam. Perhitungan laju pindah panas ke fluida dingin dalam pipa sebagai fungsi dari karakteristik udara, laju massa melalui luas penampang laluan diperoleh sebesar 11,285W. Efektivitas sebagai rasio laju pindah panas aktual dengan panas maksimum

  16. An investigation of the predictors of photoprotection and UVR dose to the face in patients with XP

    DEFF Research Database (Denmark)

    Walburn, Jessica; Sarkany, Robert; Norton, Sam

    2017-01-01

    of clinical and psychosocial factors with the average daily UVR dose; dynamic logistic regression models will be used to investigate participant-specific psychosocial factors associated with photoprotection behaviours. ETHICS AND DISSEMINATION: This research has been approved by Camden and King's Cross...... Research Ethics Committee 15/LO/1395. The findings will be published in peer-reviewed journals and presented at national and international scientific conferences....

  17. Ultraviolet and photosynthetically active radiation can both induce photoprotective capacity allowing barley to overcome high radiation stress

    Czech Academy of Sciences Publication Activity Database

    Klem, Karel; Holub, Petr; Štroch, Michal; Nezval, J.; Špunda, Vladimír; Tříska, Jan; Jansen, M. A.; Robson, M. T.; Urban, Otmar

    2015-01-01

    Roč. 93, aug 2015 (2015), s. 74-83 ISSN 0981-9428 R&D Projects: GA MŠk LD12030; GA MŠk(CZ) LM2010007; GA MŠk EE2.3.20.0246; GA MŠk 7E12047 Institutional support: RVO:67179843 Keywords : Barley genotype * Photoinhibition * Photoprotection * Polyphenols * Xanthophylls Subject RIV: ED - Physiology Impact factor: 2.928, year: 2015

  18. Exchange Network

    Science.gov (United States)

    The Environmental Information Exchange Network (EIEN) is an Internet-based system used by state, tribal and territorial partners to securely share environmental and health information with one another and EPA.

  19. Determination of insecticides in water using in situ halide exchange reaction-assisted ionic liquid dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    Science.gov (United States)

    Li, Songqing; Gao, Haixiang; Zhang, Jiaheng; Li, Yubo; Peng, Bing; Zhou, Zhiqiang

    2011-11-01

    A dispersive liquid-liquid microextraction (DLLME) method using in situ halide exchange reaction to form ionic liquid (IL) extraction phase was developed to determine four insecticides (i.e. methoxyfenozide, tetrachlorvinphos, thiamethoxam, and diafenthiuron) in water samples. The preconcentration procedure, followed by high-performance liquid chromatography and variable wavelength detectors (VWD), enabled the formation of the immiscible IL extraction phase; the insecticides were transferred into the IL phase simultaneously, which enhanced the efficiency and sufficiency, greatly shortening the operation time. The experimental parameters affecting the extraction efficiency including volume of extraction IL, extraction and centrifugation times, volume of the sample solution and exchanging reagent, and addition of organic solvent and salt were investigated and optimized. Under optimized conditions, the extractions yielded recoveries of the target analytes from 82 to 102%. The calibration curves were linear, and the correlation coefficient ranged from 0.9990 to 0.9999 under the concentration levels of 5-200 μg/L. The relative standard deviation (n=6) was 2.9-4.6%. The limits of detection (LODs) for the four insecticides were between 0.98 and 2.54 μg/L. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A Pilot Study of the Photoprotective Effects of Strawberry-Based Cosmetic Formulations on Human Dermal Fibroblasts

    Directory of Open Access Journals (Sweden)

    Massimiliano Gasparrini

    2015-08-01

    Full Text Available Strawberry polyphenols have been extensively studied over the last two decades for their beneficial properties. Recently, their possible use in ameliorating skin conditions has also been proposed; however, their role in preventing UVA-induced damage in cosmetic formulation has not yet been investigated. Skin is constantly exposed to several environmental stressors, such as UVA radiation, that induce oxidative stress, inflammation and cell death via the production of reactive oxygen species (ROS. In the present study, we assessed the potential photoprotective capacity of different strawberry-based formulations, enriched with nanoparticles of Coenzyme Q10 and with sun protection factor 10 (SPF10, in human dermal fibroblasts (HuDe exposed to UVA radiation. We confirmed that strawberries are a very rich source of polyphenols, anthocyanins and vitamins, and possess high total antioxidant capacity. We also showed that strawberry extracts (25 μg/mL–1 mg/mL exert a noticeable photoprotection in HuDe, increasing cell viability in a dose-dependent way, and that these effects are potentiated by the presence of CoQ10red (100 μg/mL. We have demonstrated for the first time that the topical use of strawberry extract may provide good photoprotection, even if more in-depth studies are strongly encouraged in order to evaluate the cellular and molecular effects of strawberry protection.

  1. Screening by coral green fluorescent protein (GFP)-like chromoproteins supports a role in photoprotection of zooxanthellae

    Science.gov (United States)

    Smith, E. G.; D'Angelo, C.; Salih, A.; Wiedenmann, J.

    2013-06-01

    Green fluorescent protein (GFP)-like pigments are responsible for the vivid colouration of many reef-building corals and have been proposed to act as photoprotectants. Their role remains controversial because the functional mechanism has not been elucidated. We provide direct evidence to support a photoprotective role of the non-fluorescent chromoproteins (CPs) that form a biochemically and photophysically distinct group of GFP-like proteins. Based on observations of Acropora nobilis from the Great Barrier Reef, we explored the photoprotective role of CPs by analysing five coral species under controlled conditions. In vitro and in hospite analyses of chlorophyll excitation demonstrate that screening by CPs leads to a reduction in chlorophyll excitation corresponding to the spectral properties of the specific CPs present in the coral tissues. Between 562 and 586 nm, the CPs maximal absorption range, there was an up to 50 % reduction of chlorophyll excitation. The screening was consistent for established and regenerating tissue and amongst symbiont clades A, C and D. Moreover, among two differently pigmented morphs of Acropora valida grown under identical light conditions and hosting subclade type C3 symbionts, high CP expression correlated with reduced photodamage under acute light stress.

  2. Parametric CFD Analysis to Study the Influence of Fin Geometry on the Performance of a Fin and Tube Heat Exchanger

    DEFF Research Database (Denmark)

    Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

    2016-01-01

    Multiphysics software COMSOL v5.2. The numerical results are obtained for Reynolds number in a range from 5000 to 13000 and verified with the experimentally developed correlations. Dimensionless performance parameters such as Nusselt number, Euler number, efficiency index, and area-goodness factor...

  3. The Effect of Financial Leverage, Employee Stock Ownership Program and Firm Size on Firm Performance of Companies Listed in Indonesia Stock Exchange

    Directory of Open Access Journals (Sweden)

    Nurainun Bangun

    2017-07-01

    Full Text Available The purpose of this research is to examine and to obtain affected empirical evidence of financial leverage, firm size and employee stock ownership program (ESOP to firm performance in manufacturing company in Indonesian Stock Exchange on 2013-2015. Independent variables in this research are Financial Leverage (DER, Firm Size and Employee Stock Ownership Program (ESOP. Dependent variables in this research are Return on Assets (ROA and Return On Equity (ROE. The results Showed that the simultaneous test of three independent variables Significantly afftected to the ROA and ROE. The partial tests of Financial Leverage (proxy DER and Firm Size Significantly affected to ROA and ROE. But, the results Showed that the Employee Stock Ownership Program (ESOP did not Affect to ROA and ROE.

  4. An enzymatic method for the determination of fructans in foods and food products - Comparison of the results by high performance anion exchange chromatography with pulsed amperemetric detection

    DEFF Research Database (Denmark)

    Andersen, Rikke; Sørensen, A.

    1999-01-01

    We report a new and non-equipment demanding method of measuring the content of fructans as well as the contents of free glucose, free fructose and sucrose in foods and food products enzymatically. This method comprises hydrolysis of fructans into D-glucose and D-fructose enzymatically...... and measurement of the released sugars enzymatically. Sucrose is hydrolysed by alpha-glucosidase instead of beta-fructosidase, which is normally used. In addition, sucrose is measured in the form of D-fructose instead of the typical D-glucose form, and the fructanase used to hydrolyse the fructans has fewer side...... effects than the fructanase reported as normally used. The method is tested on ten standard substances and five fructan products, and nine foods and food products are also analysed. The enzymatic measurement of the released sugars is confirmed by measurements done by high performance anion exchange...

  5. The Prediction Performance of Asset Pricing Models and Their Capability of Capturing the Effects of Economic Crises: The Case of Istanbul Stock Exchange

    Directory of Open Access Journals (Sweden)

    Erol Muzır

    2010-09-01

    Full Text Available This paper is prepared to test the common opinion that the multifactor asset pricing models produce superior predictions as compared to the single factor models and to evaluate the performance of Arbitrage Pricing Theory (APT and Capital Asset Pricing Model (CAPM. For this purpose, the monthly return data from January 1996 and December 2004 of the stocks of 45 firms listed at Istanbul Stock Exchange were used. Our factor analysis results show that 68,3 % of the return variation can be explained by five factors. Although the APT model has generated a low coefficient of determination, 28,3 %, it proves to be more competent in explaining stock return changes when compared to CAPM which has an inferior explanation power, 5,4 %. Furthermore, we have observed that APT is more robust also in capturing the effects of any economic crisis on return variations.

  6. Analytical Method for Sugar Profile in Pet Food and Animal Feeds by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection.

    Science.gov (United States)

    Ellingson, David J; Anderson, Phillip; Berg, Daniel P

    2016-01-01

    There is a need for a standardized, accurate, rugged, and consistent method to measure for sugars in pet foods and animal feeds. Many traditional standard sugar methods exist for other matrixes, but when applied in collaborative studies there was poor agreement and sources of error identified with those standard methods. The advancement in technology over the years has given us the ability to improve on these standard methods of analysis. A method is described here that addresses these common issues and was subjected to a single-laboratory validation to assess performance on a wide variety of pet foods and animal feeds. Of key importance to the method performance is the sample preparation before extraction, type of extraction solvent, postextraction cleanup, and, finally, optimized chromatography using high-performance anion exchange chromatography with pulsed amperometric detection. The results obtained from the validation demonstrate how typical issues seen with these matrixes can influence performance of sugar analysis. The results also demonstrate that this method is fit-for-purpose and can meet the challenges of sugar analysis in pet food and animal feeds to lay the foundation for a standardized method of analysis.

  7. Synthesis and characterization of high performing Fe-N-C catalyst for oxygen reduction reaction (ORR) in Alkaline Exchange Membrane Fuel Cells

    Science.gov (United States)

    Hossen, Md Mosaddek; Artyushkova, Kateryna; Atanassov, Plamen; Serov, Alexey

    2018-01-01

    In this article, three different Fe-N-C oxygen reduction reaction (ORR) catalysts derived from different organic molecules i.e. Fe-NMG, Fe-NMP, Fe-MBZ have been synthesized, characterized by physical-chemical methods and studied in the reaction of oxygen reduction (ORR). It is found that Fe-NMG shows higher ORR performance than Fe-NMP and Fe-MBZ, by both rotating ring disk electrode (RRDE) and fuel cell tests. From characterization and surface analysis, it can be explained that the presence of higher amount of surface oxides and pyridinic nitrogen is the main reason for better performance towards ORR in alkaline media. To achieve the highest performance in alkaline exchange membrane fuel cell (AEMFC), the optimization of catalyst layer composition using various concentrations of ionomer (Tokuyama, AS4) was performed. At the optimum cathode layer configuration utilizing Fe-NMG produces the peak power density of 218 mWcm-2, which is one of the highest values presented in the open literature.

  8. Experimental investigation and numerical comparison of the performance of a proton exchange membrane fuel cell at different channel geometry

    Science.gov (United States)

    Khazaee, I.

    2015-08-01

    In this study, the performance of a PEM fuel cell is investigated experimentally and numerically by changing the geometry of the channels. At first an experimental setup is used and three different fuel cells with rectangular, elliptical and triangular serpentine channels are constructed. The active area of each cell is 25 cm2 that its weight is 1,300 g. The material of the gas diffusion layer is carbon clothes, the membrane is nafion 117 and the catalyst layer is a plane with 0.004 g cm-2 platinum. Then a complete three-dimensional model for fuel cell is used to investigate the effect of using this channels geometry on the performance. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components. The results show that the predicted polarization curves by using this model are in good agreement with the experimental results. Also the results show that when the geometry of channel is rectangular the performance of the cell is better than the triangular and elliptical channel.

  9. Enhanced performance and stability of high temperature proton exchange membrane fuel cell by incorporating zirconium hydrogen phosphate in catalyst layer

    Science.gov (United States)

    Barron, Olivia; Su, Huaneng; Linkov, Vladimir; Pollet, Bruno G.; Pasupathi, Sivakumar

    2015-03-01

    Zirconium hydrogen phosphate (ZHP) together with polytetrafluoroethylene (PTFE) polymer binder is incorporated into the catalyst layers (CLs) of ABPBI (poly(2,5-benzimidazole))-based high temperature polymer electrolyte membrane fuel cell (HT-PEMFCs) to improve its performance and durability. The influence of ZHP content (normalised with respect to dry PTFE) on the CL properties are structurally characterised by scanning electron microscopy (SEM) and mercury intrusion porosimetry. Electrochemical analyses of the resultant membrane electrode assemblies (MEAs) are performed by recording polarisation curves and impedance spectra at 160 °C, ambient pressure and humidity. The result show that a 30 wt.% ZHP/PTFE content in the CL is optimum for improving fuel cell performance, the resultant MEA delivers a peak power of 592 mW cm-2 at a cell voltage of 380 mV. Electrochemical impedance spectra (EIS) indicate that 30% ZHP in the CL can increase the proton conductivity compared to the pristine PTFE-gas diffusion electrode (GDE). A short term stability test (∼500 h) on the 30 wt.% ZHP/PTFE-GDE shows a remarkable high durability with a degradation rate as low as ∼19 μV h-1 at 0.2 A cm-2, while 195 μV h-1 was obtained for the pristine GDE.

  10. The Influence of R&D Policy on Performance of the Companies Listed with Bucharest Stock Exchange (through Intangible Assets

    Directory of Open Access Journals (Sweden)

    Ion Stancu

    2008-09-01

    Full Text Available In the new economy, R&D potential of the companies (reflected by intangible assets tends to make the difference between competing enterprises. Although investing in tangible assets is still viewed as important, the researchers have discovered that investors on capital market tend to buy stocks of the high-tech companies promoting a policy of increasing R&D expenditures.The results of the present study on the Romanian economy reveals the correlation between the variation of intangible assets of the chemicals and pharmaceuticals companies (high-tech and their performance – reflected by EPS and PER coefficients.

  11. Hydrogen exchange

    DEFF Research Database (Denmark)

    Jensen, Pernille Foged; Rand, Kasper Dyrberg

    2016-01-01

    Hydrogen exchange (HX) monitored by mass spectrometry (MS) is a powerful analytical method for investigation of protein conformation and dynamics. HX-MS monitors isotopic exchange of hydrogen in protein backbone amides and thus serves as a sensitive method for probing protein conformation...... and dynamics along the entire protein backbone. This chapter describes the exchange of backbone amide hydrogen which is highly quenchable as it is strongly dependent on the pH and temperature. The HX rates of backbone amide hydrogen are sensitive and very useful probes of protein conformation......, as they are distributed along the polypeptide backbone and form the fundamental hydrogen-bonding networks of basic secondary structure. The effect of pressure on HX in unstructured polypeptides (poly-dl-lysine and oxidatively unfolded ribonuclease A) and native folded proteins (lysozyme and ribonuclease A) was evaluated...

  12. High-performance membrane electrode assembly with multi-functional Pt/SnO2eSiO2/C catalyst for proton exchange membrane fuel cell operated under low-humidity conditions

    CSIR Research Space (South Africa)

    Hou, S

    2016-06-01

    Full Text Available A novel self-humidifying membrane electrode assembly (MEA) with homemade multifunctional Pt/SnO(sub2)-SiO(sub2)/C as the anode was developed to improve the performance of a proton exchange membrane fuel cell under low humidity. The MEAs' performance...

  13. Effect of Disproportional Voting Rights on Firm’s Market Performance: Evidence from Chinese Firms Cross-Listed on U.S. Exchanges

    Directory of Open Access Journals (Sweden)

    Abdullah

    2017-09-01

    Full Text Available Dual-class firms face great criticism as it is believed that firms choose this structure to expropriate minority shareholders’ wealth. We compare market performance of Chinese dual-class firms with their single-class counterparts by constructing a list of Chinese firms cross-listed on U.S. exchanges. We find, contrary to the literature, that Chinese dual-class firms are outperforming in terms of market performance measured by Tobin’s Q, P/E ratio, and abnormal return in both subsequent years after the initial public offering (IPO. The reason for contrary results is that Chinese dual-class firms bond themselves to high U.S. standards from low local Chinese standards, and it is evident from the literature that when a firm bonds itself to high standards it shows a credible commitment towards minority shareholders’ rights, as well as focus on upright performance rather than investing in value-destroying projects and competes to survive in the market that imposes the high standards.

  14. Comparison of The Performance of Proton Exchange Membrane Fuel Cell (PEMFC Electrodes with Different Carbon Powder Content and Methods of Manufacture

    Directory of Open Access Journals (Sweden)

    Dedi Rohendi

    2016-11-01

    Full Text Available Carbon powder in the gas diffusion layer (GDL contained in the membrane electrode assembly (MEA has an important role in the flow of electrons and reactant gas. Meanwhile, the method of making the electrode is one of the many studies conducted to determine the most appropriate method to use. Comparative study of the performance of proton exchange membrane fuel cell (PEMFC electrodes with different carbon powder content (vulcan XC-72 in the GDL and methods of manufacture of the electrode between casting and spraying method has been carried out. The spraying method consists of one layer and three layer of catalyst layer (CL. The content of carbon powder in the GDL as much as 3 mg cm-2 has a better performance compared to 1.5 mg cm-2 with an increase of 177.78% current density at 0.6 V. Meanwhile, the manufacture of CL with three-layer spraying method has better performance compared with one-layer spraying and casting method.

  15. Photosynthetic response to fluctuating environments and photoprotective strategies under abiotic stress.

    Science.gov (United States)

    Yamori, Wataru

    2016-05-01

    Plants in natural environments must cope with diverse, highly dynamic, and unpredictable conditions. They have mechanisms to enhance the capture of light energy when light intensity is low, but they can also slow down photosynthetic electron transport to prevent the production of reactive oxygen species and consequent damage to the photosynthetic machinery under excess light. Plants need a highly responsive regulatory system to balance the photosynthetic light reactions with downstream metabolism. Various mechanisms of regulation of photosynthetic electron transport under stress have been proposed, however the data have been obtained mainly under environmentally stable and controlled conditions. Thus, our understanding of dynamic modulation of photosynthesis under dramatically fluctuating natural environments remains limited. In this review, first I describe the magnitude of environmental fluctuations under natural conditions. Next, I examine the effects of fluctuations in light intensity, CO2 concentration, leaf temperature, and relative humidity on dynamic photosynthesis. Finally, I summarize photoprotective strategies that allow plants to maintain the photosynthesis under stressful fluctuating environments. The present work clearly showed that fluctuation in various environmental factors resulted in reductions in photosynthetic rate in a stepwise manner at every environmental fluctuation, leading to the conclusion that fluctuating environments would have a large impact on photosynthesis.

  16. Development and stability studies of sunscreen cream formulations containing three photo-protective filters

    Directory of Open Access Journals (Sweden)

    Slim Smaoui

    2017-02-01

    Full Text Available The present study aimed to formulate and subsequently evaluate sunscreen cream (W/O/W emulsion containing three photo-protective filters: benzophenone-3, ethylhexyl methoxycinnamate and titanium dioxide at different percentages. Formulations were stored at 8, 25 and 40 °C for four weeks to investigate their stability. Color, centrifugation, liquefaction, phase separation, pH and Sun Protection Factor (SPF of sunscreen cream formulations were determined. The microbiological stability of the creams was also evaluated and the organoleptic quality was carried out for 28 days. Interestingly, the combination of 7% Benzophenone-3, 7% Ethylhexyl methoxycinnamate and 6% Titanium dioxide preserved physicochemical properties of the product and was efficient against the development of different spoilage microorganisms as well as aerobic plate counts, Pseudomonas aeruginosa, Staphylococcus aureus, and yeast and mold counts. Furthermore, a good stability was observed for all formulations throughout the experimental period. The newly formulated sunscreen cream was proved to exhibit a number of promising properties and attributes that might open new opportunities for the development of more efficient, safe, and cost-effective skin-care, cosmetic, and pharmaceutical products.

  17. Photoprotection by foliar anthocyanins mitigates effects of boron toxicity in sweet basil (Ocimum basilicum).

    Science.gov (United States)

    Landi, Marco; Guidi, Lucia; Pardossi, Alberto; Tattini, Massimiliano; Gould, Kevin S

    2014-11-01

    Boron (B) toxicity is an important agricultural problem in arid environments. Excess edaphic B compromises photosynthetic efficiency, limits growth and reduces crop yield. However, some purple-leafed cultivars of sweet basil (Ocimum basilicum) exhibit greater tolerance to high B concentrations than do green-leafed cultivars. We hypothesised that foliar anthocyanins protect basil leaf mesophyll from photo-oxidative stress when chloroplast function is compromised by B toxicity. Purple-leafed 'Red Rubin' and green-leafed 'Tigullio' cultivars, grown with high or negligible edaphic B, were given a photoinhibitory light treatment. Possible effects of photoabatement by anthocyanins were simulated by superimposing a purple polycarbonate filter on the green leaves. An ameliorative effect of light filtering on photosynthetic quantum yield and on photo-oxidative load was observed in B-stressed plants. In addition, when green protoplasts from both cultivars were treated with B and illuminated through a screen of anthocyanic protoplasts or a polycarbonate film which approximated cyanidin-3-O-glucoside optical properties, the degree of photoinhibition, hydrogen peroxide production, and malondialdehyde content were reduced. The data provide evidence that anthocyanins exert a photoprotective role in purple-leafed basil mesophyll cells, thereby contributing to improved tolerance to high B concentrations.

  18. Photoprotective Effects of Cycloheterophyllin against UVA-Induced Damage and Oxidative Stress in Human Dermal Fibroblasts.

    Directory of Open Access Journals (Sweden)

    Cheng-Hua Huang

    Full Text Available Ultraviolet (UV radiation, particularly ultraviolet A (UVA, is known to play a major role in photoaging of the human skin. Many studies have demonstrated that UV exposure causes the skin cells to generate reactive oxygen species and activates the mitogen-activated protein kinase (MAPK pathway. Previous studies have also demonstrated that cycloheterophyllin has an antioxidant effect and can effectively scavenge free radicals. Extending the aforementioned investigations, in this study, human dermal fibroblasts were used to investigate the protective effect of cycloheterophyllin against UV-induced damage. We found that cycloheterophyllin not only significantly increased cell viability, but also attenuated the phosphorylation of MAPK after UVA exposure. Furthermore, cycloheterophyllin could reduce hydrogen peroxide (H2O2 generation and down-regulate H2O2-induced MAPK phosphorylation. In the in vivo studies, the topical application of cycloheterophyllin before UVA irradiation significantly decreased trans-epidermal water loss (TEWL, erythema, and blood flow rate. These results indicate that cycloheterophyllin is a photoprotective agent that inhibits UVA-induced oxidative stress and damage, and could be used in the research on and prevention of skin photoaging.

  19. Rosmarinic acid, a photo-protective agent against UV and other ionizing radiations.

    Science.gov (United States)

    Sánchez-Campillo, M; Gabaldon, J A; Castillo, J; Benavente-García, O; Del Baño, M J; Alcaraz, M; Vicente, V; Alvarez, N; Lozano, J A

    2009-02-01

    Solar UV and other ionizing radiations cause a generation of reactive oxygen species, induce cellular DNA damage and alter skin homeostasis. The use of exogenous antioxidants is increasingly frequents, we attempt to demonstrate that a rosmarinic acid extract acts as photo-protector; both free radical scavenger as an inducer of the body's own endogenous defence mechanisms by regulating tyrosinase activity and stimulating melanin production. Malonyldialdehyde formation (TBARS) was delayed when RA was used. The protection factor was 3.24 times vs AA. TEAC value for RA was 1.6 times vs AA. The radioprotective-antimutagenic effects of RA were measure using the micronucleus test. The level of micronucleous for treatments before irradiation was: RA [14]photo-protective agent.

  20. Chloroplast movement provides photoprotection to plants by redistributing PSII damage within leaves.

    Science.gov (United States)

    Davis, Phillip A; Hangarter, Roger P

    2012-09-01

    Plants use light to fix carbon through the process of photosynthesis but light also causes photoinhibition, by damaging photosystem II (PSII). Plants can usually adjust their rate of PSII repair to equal the rate of damage, but under stress conditions or supersaturating light-intensities damage may exceed the rate of repair. Light-induced chloroplast movements are one of the many mechanisms plants have evolved to minimize photoinhibition. We found that chloroplast movements achieve a measure of photoprotection to PSII by altering the distribution of photoinhibition through depth in leaves. When chloroplasts are in the low-light accumulation arrangement a greater proportion of PSII damage occurs near the illuminated surface than for leaves where the chloroplasts are in the high-light avoidance arrangement. According to our findings chloroplast movements can increase the overall efficiency of leaf photosynthesis in at least two ways. The movements alter light profiles within leaves to maximize photosynthetic output and at the same time redistribute PSII damage throughout the leaf to reduce the amount of inhibition received by individual chloroplasts and prevent a decrease in photosynthetic potential.

  1. Desiccation tolerance in red and green gametophytes of Jamesoniella colorata in relation to photoprotection.

    Science.gov (United States)

    Hooijmaijers, C A M

    2008-05-01

    This study tests the hypothesis that red-leaved gametophytes of the liverwort Jamesoniella colorata (Lehm.) Schiffn., which are found in relatively dry habitats, are more desiccation tolerant than their green counterparts, which are found in moister environments, through superior photoprotective systems. The potential role of red foliar pigments in relation to water deficits is investigated by measuring cell water-relations, oxidative damage and photosynthetic responses. The presence of red pigments, or other cellular constituents, did not affect cell water-relations during dehydration and thus appear not to be involved in cell osmotic regulation. During drying, both colour morphs showed a similar non-photochemical quenching activity and did not experience significant oxidative damage, as measured by the amounts of ascorbate, malondialdehyde and photosynthetic pigments. However, the levels of oxidative damage increased directly upon rewetting the gametophytes, especially in low light conditions (25 micromol m(-2) s(-1)). The efficiency of photosystem II only recovered partially after severe water deficits in both phenotypes. However, the red gametophytes recovered faster and more completely from mild water deficits than did the greens. Moreover, they experienced significantly less photobleaching after rehydration in low light. It is suggested that red pigments and/or carotenoids in these gametophytes improve desiccation tolerance by alleviating photooxidative damage.

  2. Photoprotective properties of the fluorescent europium complex in UV-irradiated skin.

    Science.gov (United States)

    Vogt, O; Lademann, J; Rancan, F; Meinke, M C; Schanzer, S; Stockfleth, E; Sterry, W; Lange-Asschenfeldt, B

    2013-01-01

    In this study, we compared the UV-protective abilities of the europium complex compared to titanium dioxide, which represents the most common physical filter for ultraviolet light in the broad-band spectral range. The UV absorption and light transformative capacities of the europium complex were evaluated using a spectrometer with a double-integrating sphere showing that the europium complex does not only absorb and reflect UV light, but transforms it into red and infrared light. It was found that the europium complex binds to the surface of Jurkat cells in vitro. Cells incubated with the europium complex showed a significantly higher viability after UVA and UVB irradiation as compared to untreated cells and cells incubated with titanium dioxide pointing out its photoprotective properties. The europium complex and titanium dioxide show similar penetration capacities into the stratum corneum as tested in human and porcine skin using tape stripping analysis. The europium complex has proved to be an efficient UV filter with a low cyto- and phototoxic profile and therefore represents a potential candidate for use in sunscreen formulations. Copyright © 2013 S. Karger AG, Basel.

  3. Exposure to Non-Extreme Solar UV Daylight: Spectral Characterization, Effects on Skin and Photoprotection

    Science.gov (United States)

    Marionnet, Claire; Tricaud, Caroline; Bernerd, Françoise

    2014-01-01

    The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV) rays (UVA, 320–400 nm and UVB, 280–320 nm). The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions. Zenithal sun exposure (for example on a beach around noon under a clear sky) can rapidly induce visible and well-characterized clinical consequences such as sunburn, predominantly induced by UVB. However, a limited part of the global population is exposed daily to such intense irradiance and until recently little attention has been paid to solar exposure that does not induce any short term clinical impact. This paper will review different studies on non-extreme daily UV exposures with: (1) the characterization and the definition of the standard UV daylight and its simulation in the laboratory; (2) description of the biological and clinical effects of such UV exposure in an in vitro reconstructed human skin model and in human skin in vivo, emphasizing the contribution of UVA rays and (3) analysis of photoprotection approaches dedicated to prevent the harmful impact of such UV exposure. PMID:25546388

  4. Exposure to Non-Extreme Solar UV Daylight: Spectral Characterization, Effects on Skin and Photoprotection

    Directory of Open Access Journals (Sweden)

    Claire Marionnet

    2014-12-01

    Full Text Available The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV rays (UVA, 320–400 nm and UVB, 280–320 nm. The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions. Zenithal sun exposure (for example on a beach around noon under a clear sky can rapidly induce visible and well-characterized clinical consequences such as sunburn, predominantly induced by UVB. However, a limited part of the global population is exposed daily to such intense irradiance and until recently little attention has been paid to solar exposure that does not induce any short term clinical impact. This paper will review different studies on non-extreme daily UV exposures with: (1 the characterization and the definition of the standard UV daylight and its simulation in the laboratory; (2 description of the biological and clinical effects of such UV exposure in an in vitro reconstructed human skin model and in human skin in vivo, emphasizing the contribution of UVA rays and (3 analysis of photoprotection approaches dedicated to prevent the harmful impact of such UV exposure.

  5. High Pt Loading on Polydopamine Functionalized Graphene as a High Performance Cathode Electrocatalyst for Proton Exchange Membrane Fuel Cells

    Directory of Open Access Journals (Sweden)

    Monireh Faraji

    2016-04-01

    Full Text Available Morphology and size of platinum nanoparticles are a crucial factor in improving their catalytic activity and stability. Here, we firstly report the synthesis of high loading Pt nanoparticles on polydopamine reduced Graphene. The loading concentration of Pt (nanoparticles NPs on Graphene can be adjusted in the range of 60-70%.With the insertion of polydopamine between Graphene oxide sheets, stacking of Graphene can be effectively prevented, promoting diffusion of oxygen molecules through the Graphene sheets and enhancing the oxygen reduction reaction electrocatalytic activity. Compared to commercial catalysts (i.e., state-of-the-art Pt/C catalyst the as synthesized Pt supported polydopamine grafted reduced graphite oxide (Pt@PDA-rGO hybrid displays very high oxygen reduction reaction catalytic activities. We propose a unique 2D profile of the polydopamine-rGO role as a barrier preventing leaching of Pt into the electrolyte. The fabricated electrodes were evaluated with electrochemical techniques for oxygen reduction reaction and the obtained results were further verified by the transmission electron microscopy micrographs on the microstructure of the integrated pt@PDA-rGO structures. It has been revealed that the electrochemical impedance spectroscopy technique can provide more explicit information than polarization curves on the performance dependence on charge-transfer and mass transport processes at different overpotential regions.

  6. Exchange Options

    NARCIS (Netherlands)

    Jamshidian, F.

    2007-01-01

    The contract is described and market examples given. Essential theoretical developments are introduced and cited chronologically. The principles and techniques of hedging and unique pricing are illustrated for the two simplest nontrivial examples: the classical Black-Scholes/Merton/Margrabe exchange

  7. La and Al co-doped CaMnO 3 perovskite oxides: From interplay of surface properties to anion exchange membrane fuel cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Dzara, Michael J.; Christ, Jason M.; Joghee, Prabhuram; Ngo, Chilan; Cadigan, Christopher A.; Bender, Guido; Richards, Ryan M.; O' Hayre, Ryan; Pylypenko, Svitlana

    2018-01-01

    This work reports the first account of perovskite oxide and carbon composite oxygen reduction reaction (ORR) catalysts integrated into anion exchange membrane fuel cells (AEMFCs). Perovskite oxides with a theoretical stoichiometry of Ca0.9La0.1Al0.1Mn0.9O3-d are synthesized by an aerogel method and calcined at various temperatures, resulting in a set of materials with varied surface chemistry and surface area. Material composition is evaluated by X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The perovskite oxide calcined at 800 degrees C shows the importance of balance between surface area, purity of the perovskite phase, and surface composition, resulting in the highest ORR mass activity when evaluated in rotating disk electrodes. Integration of this catalyst into AEMFCs reveals that the best AEMFC performance is obtained when using composites with 30:70 perovskite oxide:carbon composition. Doubling the loading leads to an increase in the power density from 30 to 76 mW cm-2. The AEMFC prepared with a composite based on perovskite oxide and N-carbon achieves a power density of 44 mW cm-2, demonstrating an ~50% increase when compared to the highest performing composite with undoped carbon at the same loading.

  8. Xylem anatomy correlates with gas exchange, water-use efficiency and growth performance under contrasting water regimes: evidence from Populus deltoides x Populus nigra hybrids.

    Science.gov (United States)

    Fichot, Régis; Laurans, Françoise; Monclus, Romain; Moreau, Alain; Pilate, Gilles; Brignolas, Franck

    2009-12-01

    Six Populus deltoides Bartr. ex Marsh. x P. nigra L. genotypes were selected to investigate whether stem xylem anatomy correlated with gas exchange rates, water-use efficiency (WUE) and growth performance. Clonal copies of the genotypes were grown in a two-plot common garden test under contrasting water regimes, with one plot maintained irrigated and the other one subjected to moderate summer water deficit. The six genotypes displayed a large range of xylem anatomy, mean vessel and fibre diameter varying from about 40 to 60 microm and from 7.5 to 10.5 microm, respectively. Decreased water availability resulted in a reduced cell size and an important rise in vessel density, but the extent of xylem plasticity was both genotype and trait dependent. Vessel diameter and theoretical xylem-specific hydraulic conductivity correlated positively with stomatal conductance, carbon isotope discrimination and growth performance-related traits and negatively with intrinsic WUE, especially under water deficit conditions. Vessel diameter and vessel density measured under water deficit conditions correlated with the relative losses in biomass production in response to water deprivation; this resulted from the fact that a more plastic xylem structure was generally accompanied by a larger loss in biomass production.

  9. Characterization of phosphoantigens by high-performance anion-exchange chromatography-electrospray ionization ion trap mass spectrometry and nanoelectrospray ionization ion trap mass spectrometry.

    Science.gov (United States)

    Pont, F; Luciani, B; Belmant, C; Fournié, J J

    2001-08-01

    New phosphorylated microbial metabolites referred to as phosphoantigens activate immune responses in humans. Although these molecules have leading applications in medical research, no direct method allows their rapid and unambiguous structural identification. Here, we interfaced online HPAEC (high performance anion-exchange chromatography) with ESI-ITMS (electrospray ionization ion trap mass spectrometry) to identify such pyrophosphorylated molecules. A self-regenerating anion suppressor located upstream of electrospray ionization enabled the simultaneous detection of pyrophosphoester by conductimetry, UV and MS. By HPAEC-ITMS and HPAEC-ITMS2, a single run permitted characterization of reference phosphoantigens and of related structures. Although all compounds were resolved by HPAEC, MS enabled their detection and identification by [M-H]- and fragment ions. Isobaric phosphoantigen analogues were also separated by HPAEC and distinguished by MS2. The relevance of this device was demonstrated for phosphoantigens analysis in human urine and plasma. Furthermore, identification of natural phosphoantigens by automatically generated 2D mass spectra from nano-ESI-ITMS is presented. This last technique permits the simultaneous performance of molecular screening of natural phosphoantigen extracts and their identification.

  10. La and Al co-doped CaMnO3 perovskite oxides: From interplay of surface properties to anion exchange membrane fuel cell performance

    Science.gov (United States)

    Dzara, Michael J.; Christ, Jason M.; Joghee, Prabhuram; Ngo, Chilan; Cadigan, Christopher A.; Bender, Guido; Richards, Ryan M.; O'Hayre, Ryan; Pylypenko, Svitlana

    2018-01-01

    This work reports the first account of perovskite oxide and carbon composite oxygen reduction reaction (ORR) catalysts integrated into anion exchange membrane fuel cells (AEMFCs). Perovskite oxides with a theoretical stoichiometry of Ca0.9La0.1Al0.1Mn0.9O3-δ are synthesized by an aerogel method and calcined at various temperatures, resulting in a set of materials with varied surface chemistry and surface area. Material composition is evaluated by X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The perovskite oxide calcined at 800 °C shows the importance of balance between surface area, purity of the perovskite phase, and surface composition, resulting in the highest ORR mass activity when evaluated in rotating disk electrodes. Integration of this catalyst into AEMFCs reveals that the best AEMFC performance is obtained when using composites with 30:70 perovskite oxide:carbon composition. Doubling the loading leads to an increase in the power density from 30 to 76 mW cm-2. The AEMFC prepared with a composite based on perovskite oxide and N-carbon achieves a power density of 44 mW cm-2, demonstrating an ∼50% increase when compared to the highest performing composite with undoped carbon at the same loading.

  11. Partially hydrolyzed guar gum characterization and sensitive quantification in food matrices by high performance anion exchange chromatography with pulsed amperometric detection--validation using accuracy profile.

    Science.gov (United States)

    Mercier, G; Campargue, C

    2012-11-02

    Interest concerning functional ingredients and especially dietary fibres has been growing in recent years. At the same time, the variety of ingredient accepted as dietary fibres and their mixing at low level in complex matrices have considerably complicated their quantitative analysis by approved AOAC methods. These reasons have led to the specific development of an innovative analytical method performed by high-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection (PAD) to detect and quantify partially hydrolyzed guar gum (PHGG) in fruit preparation and dairy matrices. The analytical methodology was divided in two steps which could be deployed separately or in conjunction. The first, consists in a complete characterization of PHGG by size exclusion chromatography (SEC) with multi-angle light scattering and refractive index detection and HPAEC-PAD to determine its physico-chemical properties and galactomannans content, and the second step is the development of a new HPAEC-PAD method for PHGG direct quantification in complex matrices (dairy product). Validation in terms of detection and quantification limits, linearity of the analytical range, average accuracy (recovery, trueness) and average uncertainty were statistically carried out with accuracy profile. Overall, this new chromatographic method has considerably improved the possibility to quantify without fractionation treatment, low level of dietary fibres emerging from specific galactomannans, in complex matrices and many foodstuffs. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Telephone Exchange Maintenance

    CERN Document Server

    2005-01-01

    Urgent maintenance work on CERN telephone exchanges will be performed on 24 March from 6 a.m. to 8 a.m. Telephone services may be disrupted or even interrupted during this time. For more details, please contact us by email at Standard.Telephone@cern.ch.

  13. Effect of the type of ion exchange membrane on performance, ion transport, and pH in biocatalyzed electrolysis of wastewater

    NARCIS (Netherlands)

    Rozendal, R.A.; Sleutels, T.H.J.A.; Hamelers, H.V.M.; Buisman, C.J.N.

    2008-01-01

    Previous studies have shown that the application of cation exchange membranes (CEMs) in bioelectrochemical systems running on wastewater can cause operational problems. In this paper the effect of alternative types of ion exchange membrane is studied in biocatalyzed electrolysis cells. Four types of

  14. High Temperature Heat Exchanger Project

    Energy Technology Data Exchange (ETDEWEB)

    Anthony E. Hechanova, Ph.D.

    2008-09-30

    The UNLV Research Foundation assembled a research consortium for high temperature heat exchanger design and materials compatibility and performance comprised of university and private industry partners under the auspices of the US DOE-NE Nuclear Hydrogen Initiative in October 2003. The objectives of the consortium were to conduct investigations of candidate materials for high temperature heat exchanger componets in hydrogen production processes and design and perform prototypical testing of heat exchangers. The initial research of the consortium focused on the intermediate heat exchanger (located between the nuclear reactor and hydrogen production plan) and the components for the hydrogen iodine decomposition process and sulfuric acid decomposition process. These heat exchanger components were deemed the most challenging from a materials performance and compatibility perspective

  15. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

  16. Experimental study of clamping effects on the performances of a single proton exchange membrane fuel cell and a 10-cell stack

    Science.gov (United States)

    Wen, Chih-Yung; Lin, Yu-Sheng; Lu, Chien-Heng

    The contact pressure distribution is known to have significant influences on the contact ohmic resistance, porosity of gas diffusion layers (GDLs) and performance of the proton exchange membrane fuel cell (PEMFC) consequently. This work experimentally investigated the effects of various combinations of bolt configuration and clamping torque on the corresponding contact pressure distributions and performances of a single PEMFC and a 10-cell stack. The pressure-sensitive films (FUJI-FILM I&I) were used to visualize the contact pressure distributions under three different clamping torques and three different bolt configurations in the experiments. The importance of the proper stacking design was clearly demonstrated by these contact pressure images. The mean value and the fluctuation intensity of the contact pressure were extracted statistically from the data of pressure-sensitive films. A non-dimensional pressure fluctuation intensity, which indicates the relative dispersion to its mean value, was proposed to gauge the uniformity of the contact pressure distribution, similar to the definition of the turbulence intensity in fluid mechanics. The experimental results showed that, for the single cell under the current experiment conditions, the larger mean contact pressure tends to yield the higher maximum power, regardless of the bolt configuration and the applied torque. The uniformity of the contact pressure distribution, the ohmic resistance and the mass transport limit current had highly linear correlations with the mean contact pressure. In the case of the 10-cell stack, the effects of various combinations of bolt configuration and clamping torque on its performance and the mass transport limit current could not be reflected by the stack mean contact pressure only. Increasing the mean contact pressure improved the uniformity of the contact pressure distribution and reduced the contact ohmic resistance, in general. However, the maximum power did not increase

  17. Rice bran and raspberry seed oil-based nanocarriers with self-antioxidative properties as safe photoprotective formulations.

    Science.gov (United States)

    Niculae, Gabriela; Lacatusu, Ioana; Badea, Nicoleta; Stan, Raluca; Vasile, Bogdan Stefan; Meghea, Aurelia

    2014-04-01

    The aim of this research was to develop advanced lipid nanocarriers based on renewable vegetable resources (rice bran oil and raspberry seed oil) that possess self-antioxidative properties, having advantages in terms of minimal side effects and exhibiting the ability to simultaneously co-encapsulate and co-release two active compounds. The focus has been oriented towards developing safe cosmetic formulations with broad-spectrum photoprotection based on these new lipid nanocarriers that contain large amounts of vegetable oils and low concentrations of synthetic UVA and UVB filters (butyl-methoxydibenzoylmethane - BMDBM and octocrylene - OCT). The lipid nanocarriers have a spherical shape and show good physical stability, with a zeta potential in the range of -25.5 to -32.4 mV. Both vegetable oils play a key role in the preparation of efficient nanocarriers, leading to a less ordered arrangement of the lipid core that offers many spaces for the entrapment of large amounts of BMDBM (79%) and OCT (90%), as wells as improved antioxidant activity and UV absorption properties, particularly for the lipid nanocarriers prepared from rice bran oil. By formulating the lipid nanocarriers into creams containing only 3.5% of the UV filters and 10.5% of the vegetable oils, the resulting sunscreens exhibited improved photoprotection, reflecting up to 91% and 93% of UVA and UVB rays, respectively. A new direction of research achieved by this study is the multiple release strategy of both UV filters from the same lipid nanocarrier. After 24 hours, a slow release of BMDBM (less than 4%) and OCT (17.5%) was obtained through a Fick diffusion process. This study demonstrates a significant advance in the areas of both nanotechnology and cosmetics, developing safer cosmetic formulations that possess broad antioxidant, photoprotective and co-release effectiveness due to the existence of a high content of nanostructured vegetable oils combined with a low amount of synthetic UV filters in the

  18. High irradiance induces photoprotective mechanisms and a positive effect on NH4+ stress in Pisum sativum L.

    Science.gov (United States)

    Ariz, Idoia; Esteban, Raquel; García-Plazaola, Jose Ignacio; Becerril, José María; Aparicio-Tejo, Pedro María; Moran, Jose Fernando

    2010-09-01

    Photosynthesis provides plant metabolism with reduced carbon (C) but is also the main source of oxidative stress in plants. Likewise, high doses of NH(4)(+) as sole N source have been reported to be toxic for most plants, resulting in reduced plant growth and restricting C availability. The combination of high photosynthetic photon flux densities (PPFD) and NH(4)(+) nutrition may provide higher C availability but could also have a detrimental effect on the plants, therefore the objective of this study is to evaluate whether NH(4)(+) induces photo-oxidative stress that is exacerbated under high light conditions. Pea plants (Pisum sativum cv. sugar-snap) were grown hydroponically with NH(4)(+) (0.5, 2.5, 5 and 10 mM) under high (750 micromol photons m(-2)s(-1)) or low PPFD conditions (350 micromol photons m(-2)s(-1)). High PPFD contributes to a higher tolerance to ammonium by pea plants, as it originated higher biomass content due to higher photosynthetic rates. However, a deficit of N (0.5 and 2.5 mM NH(4)(+)) under high PPFD conditions caused an antioxidant response, as indicated by increased photoprotective pigment and chloroplastic superoxide dismutase contents. Plants grown with higher doses of N and high PPFD showed less need for photoprotection. An increase in the specific leaf weight (SLW) ratio was observed associated not only with high PPFDs but also with the highest NH(4)(+) dose. Overall, these results demonstrate that, despite the activation of some photoprotective responses at high PPFD, there were no photoinhibitory symptoms and a positive effect on NH(4)(+) toxicity, thus suggesting that the harmful effects of NH(4)(+) are not directly related to the generation of photo-oxidative stress. Copyright 2010 Elsevier GmbH. All rights reserved.

  19. Bioaccumulation of photoprotective compounds in copepods: environmental triggers and sources of intra-specific variability

    Science.gov (United States)

    Zagarese, H. E.; García, P.; Diéguez, M. D.; Ferraro, M. A.

    2012-12-01

    Ultraviolet radiation (UVR) and temperature are two globally important abiotic factors affecting freshwater ecosystems. Planktonic organisms have developed a battery of counteracting mechanisms to minimize the risk of being damaged by UVR, which respond to three basic principles: avoid, protect, repair. Copepods are among the most successful zooplankton groups. They are highly adaptable animals, capable of displaying flexible behaviors, physiologies, and life strategies. In particular, they are well equipped to cope with harmful UVR. Their arsenal includes vertical migration, accumulation of photoprotective compounds, and photorepair. The preference for a particular strategy is affected by a plethora of environmental (extrinsic) parameters, such as the existence of a depth refuge, the risk of visual predation, and temperature. Temperature modifies the environment (e.g. the lake thermal structure), and animal metabolism (e.g., swimming speed, bioaccumulation of photoprotective compounds). In addition, the relative weight of UVR-coping strategies is also influenced by the organism (intrinsic) characteristics (e.g., inter- and intra-specific variability). The UV absorbing compounds, mycosporine-like amino acids (MAAs), are widely distributed among freshwater copepods. Animals are unable to synthesize MAAs, and therefore depend on external sources for accumulating these compounds. Although copepods may acquire MAAs from their food, for the few centropagic species investigated so far, the main source of MAAs are microbial (most likely prokaryotic) organisms living in close association with the copepods. Boeckella gracilipes is a common centropagic copepod in Patagonian lakes. We suspected that its occurrence in different types of lakes, hydrologically unconnected, but within close geographical proximity, could have resulted in different microbial-copepod associations (i.e., different MAAs sources) that could translate into intra-specific differences in the accumulation

  20. Photoprotection vs. Photoinhibition of Photosystem II in Transplastomic Lettuce (Lactuca sativa) Dominantly Accumulating Astaxanthin.

    Science.gov (United States)

    Fujii, Ritsuko; Yamano, Nami; Hashimoto, Hideki; Misawa, Norihiko; Ifuku, Kentaro

    2016-07-01

    Transplastomic (chloroplast genome-modified; CGM) lettuce that dominantly accumulates astaxanthin grows similarly to a non-transgenic control with almost no accumulation of naturally occurring photosynthetic carotenoids. In this study, we evaluated the activity and assembly of PSII in CGM lettuce. The maximum quantum yield of PSII in CGM lettuce was <0.6; however, the quantum yield of PSII was comparable with that in control leaves under higher light intensity. CGM lettuce showed a lower ability to induce non-photochemical quenching (NPQ) than the control under various light intensities. The fraction of slowly recovering NPQ in CGM lettuce, which is considered to be photoinhibitory quenching (qI), was less than half that of the control. In fact, 1 O 2 generation was lower in CGM than in control leaves under high light intensity. CGM lettuce contained less PSII, accumulated mostly as a monomer in thylakoid membranes. The PSII monomers purified from the CGM thylakoids bound echinenone and canthaxanthin in addition to β-carotene, suggesting that a shortage of β-carotene and/or the binding of carbonyl carotenoids would interfere with the photophysical function as well as normal assembly of PSII. In contrast, high accumulation of astaxanthin and other carbonyl carotenoids was found within the thylakoid membranes. This finding would be associated with the suppression of photo-oxidative stress in the thylakoid membranes. Our observation suggests the importance of a specific balance between photoprotection and photoinhibition that can support normal photosynthesis in CGM lettuce producing astaxanthin. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  1. Vertical distribution of epibenthic freshwater cyanobacterial Synechococcus spp. strains depends on their ability for photoprotection.

    Directory of Open Access Journals (Sweden)

    Jens N Lohscheider

    Full Text Available BACKGROUND: Epibenthic cyanobacteria often grow in environments where the fluctuation of light intensity and quality is extreme and frequent. Different strategies have been developed to cope with this problem depending on the distribution of cyanobacteria in the water column. PRINCIPAL FINDINGS: Here we provide an experimental proof that the light intensity plays an important role in the vertical distribution of seven, closely related, epibenthic Synechococcus spp. strains isolated from various water depths from the littoral zone of Lake Constance in Germany and cultivated under laboratory conditions. Pigment analysis revealed that the amount of chlorophyll a and total carotenoids decreased with the time of light stress exposure in three phycoerythrin-rich strains collected from 7.0 m water depth and remained low during the recovery phase. In contrast, a constant level of chlorophyll a and either constant or enhanced levels of carotenoids were assayed in phycocyanin-rich strains collected from 1.0 and 0.5 m water depths. Protein analysis revealed that while the amount of biliproteins remained constant in all strains during light stress and recovery, the amount of D1 protein from photosystem II reaction centre was strongly reduced under light stress conditions in strains from 7.0 m and 1.0 m water depth, but not in strains collected from 0.5 m depth. CONCLUSION: Based on these data we propose that light intensity, in addition to light quality, is an important selective force in the vertical distribution of Synechococcus spp. strains, depending on their genetically fixed mechanisms for photoprotection.

  2. Determination of residues of the plant growth regulator chlormequat in pears by ion-exchange high performance liquid chromatography-electrospray mass spectrometry.

    Science.gov (United States)

    Startin, J R; Hird, S J; Sykes, M D; Taylor, J C; Hill, A R

    1999-07-01

    We report a method which we have used routinely for the determination of chlormequat residues in pears. After extraction with methanol, determination was performed, without clean-up, by ion-exchange HPLC using an SCX column eluted with aqueous ammonium formate-methanol, and HPLC-MS with an electrospray interface. MS and MS-MS were employed concurrently, using selected ion monitoring and selected reaction monitoring, respectively, of the 35Cl and 37Cl isotopes of the chlormequat cation and the CID transitions of each of these precursors to the common product ion at m/z 58. The method was suitable for determinations at concentrations of chlormequat cation of 0.04 mg kg-1. Concentrations determined using the four signals were in good agreement (mean RSD 3%). The mean recovery of chlormequat cation at 0.16 mg kg-1, measured using the m/z 122-->58 signal, was 86% (RSD 7%) under repeatability conditions and 88% (RSD 15%) in routine application of the method over a 3 month period. Analysis of an in-house reference sample of pears, similarly analysed over the 3 month period, gave an RSD of 10% with a mean of 0.14 mg kg-1. Mean recovery at 0.016 mg kg-1, under repeatability conditions on two occasions, was 101% (RSD 6%) and 56% (RSD 12%).

  3. The effects of performance criteria including accounting, market, and economy on the quality of financial reporting: A case study on Tehran Stock Exchange

    Directory of Open Access Journals (Sweden)

    Mohammad Mahdi Hosseini

    2013-01-01

    Full Text Available This research studies the effects of performance criteria (accounting, market and economy on the quality of financial reporting in Iran. To evaluate the variable financial reporting quality, the scores given to each company are applied based on the checklist introduced by Iranian Association of Certified Public Accountants and used for the disclosure of the information of the annual financial statements of companies. The statistical population of this research consists of the companies listed on Tehran Stock Exchange over the period 2006-2011. This research, which is classified as applied research, uses the methods of multivariate regression test. The data and hypotheses of this research are analyzed and tested using correlation test and means difference test. The results of the tests conducted on 99 companies indicate that there is a significant and positive relation between the rate of return on equity and the equality of financial reporting. There is also a significant and positive relation between earnings per share and the equality of financial reporting. However, there is no relationship between QTOBIN and the equality of financial reporting. Finally, our results indicate there is a significant and positive relation between market value-added and the equality of financial reporting.

  4. The Impact of a Surprise Dividend Increase on a Stocks Performance : the Analysis of Companies Listed on the Warsaw Stock Exchange

    Directory of Open Access Journals (Sweden)

    Tomasz Słoński

    2012-01-01

    Full Text Available The reaction of marginal investors to the announcement of a surprise dividend increase has been measured. Although field research is performed on companies listed on the Warsaw Stock Exchange, the paper has important theoretical implications. Valuation theory gives many clues for the interpretation of changes in dividends. At the start of the literature review, the assumption of the irrelevance of dividends (to investment decisions is described. This assumption is the basis for up-to-date valuation procedures leading to fundamental and fair market valuation of equity (shares. The paper is designed to verify whether the market value of stock is immune to the surprise announcement of a dividend increase. This study of the effect of a surprise dividend increase gives the chance to partially isolate such an event from dividend changes based on long-term expectations. The result of the research explicitly shows that a surprise dividend increase is on average welcomed by investors (an average abnormal return of 2.24% with an associated p-value of 0.001. Abnormal returns are realized by investors when there is a surprise increase in a dividend payout. The subsample of relatively high increases in a dividend payout enables investors to gain a 3.2% return on average. The results show that valuation models should be revised to take into account a possible impact of dividend changes on investors behavior. (original abstract

  5. Simultaneous detection of perchlorate and bromate using rapid high-performance ion exchange chromatography-tandem mass spectrometry and perchlorate removal in drinking water.

    Science.gov (United States)

    West, Danielle M; Mu, Ruipu; Gamagedara, Sanjeewa; Ma, Yinfa; Adams, Craig; Eichholz, Todd; Burken, Joel G; Shi, Honglan

    2015-06-01

    Perchlorate and bromate occurrence in drinking water causes health concerns due to their effects on thyroid function and carcinogenicity, respectively. The purpose of this study was threefold: (1) to advance a sensitive method for simultaneous rapid detection of perchlorate and bromate in drinking water system, (2) to systematically study the occurrence of these two contaminants in Missouri drinking water treatment systems, and (3) to examine effective sorbents for minimizing perchlorate in drinking water. A rapid high-performance ion exchange chromatography-tandem mass spectrometry (HPIC-MS/MS) method was advanced for simultaneous detection of perchlorate and bromate in drinking water. The HPIC-MS/MS method was rapid, required no preconcentration of the water samples, and had detection limits for perchlorate and bromate of 0.04 and 0.01 μg/L, respectively. The method was applied to determine perchlorate and bromate concentrations in total of 23 selected Missouri drinking water treatment systems during differing seasons. The water systems selected include different source waters: groundwater, lake water, river water, and groundwater influenced by surface water. The concentrations of perchlorate and bromate were lower than or near to method detection limits in most of the drinking water samples monitored. The removal of perchlorate by various adsorbents was studied. A cationic organoclay (TC-99) exhibited effective removal of perchlorate from drinking water matrices.

  6. Initial evaluation of two organic resins and their ion exchange column performance for the recovery of cesium from Hanford alkaline wastes

    Energy Technology Data Exchange (ETDEWEB)

    Bray, L.A.; Carson, K.J.; Elovich, R.J.; Carlson, C.D.; DesChane, J.R.; Kurath, D.E.

    1996-04-01

    The contents of Hanford`s 177 underground storage tanks include a mixture of sludge, salt cake and alkaline supernatant liquids. Most of the cesium is expected to be in the aqueous liquids and it is these solutions that are the focus of the cesium ion exchange removal process. This process is being designed with the goal of removing enough cesium so that the resulting low-level waste (LLW) will meet the NRC 10CFR61 class A limits for {sup 137}Cs (1 Ci/m{sup 3}). The overall objective of the WHC program is (1) to evaluate ion exchange materials for the recovery of cesium from alkaline wastes, (2) to determine their loading and elution capacities, (3) to determine the physical life cycle (including radiation and chemical stability) for selected ion exchangers, (4) to determine if basic ion exchange data can be applied to a broad range of tank wastes, and (5) to provide credible laboratory data for engineering-scale evaluation and ion exchange media selection. The goal will be to provide the technology to produce a Class A waste. The results presented in this document provide initial test cesium loading and elution results for ion exchange column operations for two selected ion exchange resins under a limited range of conditions. Data in this report can be found in PNL laboratory record books BNW 54705 and BNW 55026.

  7. EFFECT OF DIFFERENT AMOUNTS OF THE NONIONIC DETERGENTS C-10E(5) AND C-12E(5) PRESENT IN ELUENTS FOR ION-EXCHANGE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF INTEGRAL MEMBRANE-PROTEINS OF SENDAI VIRUS

    NARCIS (Netherlands)

    WELLINGWESTER, S; FEIJLBRIEF, M; KOEDIJK, DGAM; BRAAKSMA, MA; DOUMA, BRK; WELLING, GW

    1993-01-01

    Non-ionic detergents (0.03-0.5%) are used as additives to the eluents when integral membrane proteins are subjected to ion-exchange high-performance liquid chromatography (HPIEC). It is not known whether this concentration should bear some relation to the critical micelle concentration (CMC) of a

  8. Heat exchanger leakage problem location

    Directory of Open Access Journals (Sweden)

    Jícha Miroslav

    2012-04-01

    Full Text Available Recent compact heat exchangers are very often assembled from numerous parts joined together to separate heat transfer fluids and to form the required heat exchanger arrangement. Therefore, the leak tightness is very important property of the compact heat exchangers. Although, the compact heat exchangers have been produced for many years, there are still technological problems associated with manufacturing of the ideal connection between the individual parts, mainly encountered with special purpose heat exchangers, e.g. gas turbine recuperators. This paper describes a procedure used to identify the leakage location inside the prime surface gas turbine recuperator. For this purpose, an analytical model of the leaky gas turbine recuperator was created to assess its performance. The results obtained are compared with the experimental data which were acquired during the recuperator thermal performance analysis. The differences between these two data sets are used to indicate possible leakage areas.

  9. Final report on LDRD project : elucidating performance of proton-exchange-membrane fuel cells via computational modeling with experimental discovery and validation.

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao Yang (Pennsylvania State University, University Park, PA); Pasaogullari, Ugur (Pennsylvania State University, University Park, PA); Noble, David R.; Siegel, Nathan P.; Hickner, Michael A.; Chen, Ken Shuang

    2006-11-01

    In this report, we document the accomplishments in our Laboratory Directed Research and Development project in which we employed a technical approach of combining experiments with computational modeling and analyses to elucidate the performance of hydrogen-fed proton exchange membrane fuel cells (PEMFCs). In the first part of this report, we document our focused efforts on understanding water transport in and removal from a hydrogen-fed PEMFC. Using a transparent cell, we directly visualized the evolution and growth of liquid-water droplets at the gas diffusion layer (GDL)/gas flow channel (GFC) interface. We further carried out a detailed experimental study to observe, via direct visualization, the formation, growth, and instability of water droplets at the GDL/GFC interface using a specially-designed apparatus, which simulates the cathode operation of a PEMFC. We developed a simplified model, based on our experimental observation and data, for predicting the onset of water-droplet instability at the GDL/GFC interface. Using a state-of-the-art neutron imaging instrument available at NIST (National Institute of Standard and Technology), we probed liquid-water distribution inside an operating PEMFC under a variety of operating conditions and investigated effects of evaporation due to local heating by waste heat on water removal. Moreover, we developed computational models for analyzing the effects of micro-porous layer on net water transport across the membrane and GDL anisotropy on the temperature and water distributions in the cathode of a PEMFC. We further developed a two-phase model based on the multiphase mixture formulation for predicting the liquid saturation, pressure drop, and flow maldistribution across the PEMFC cathode channels. In the second part of this report, we document our efforts on modeling the electrochemical performance of PEMFCs. We developed a constitutive model for predicting proton conductivity in polymer electrolyte membranes and compared

  10. Economic photoprotection in photosystem II that retains a complete light-harvesting system with slow energy traps.

    Science.gov (United States)

    Belgio, Erica; Kapitonova, Ekaterina; Chmeliov, Jevgenij; Duffy, Christopher D P; Ungerer, Petra; Valkunas, Leonas; Ruban, Alexander V

    2014-07-11

    The light-harvesting antenna of higher plant photosystem II has an intrinsic capability for self-defence against intense sunlight. The thermal dissipation of excess energy can be measured as the non-photochemical quenching of chlorophyll fluorescence. It has recently been proposed that the transition between the light-harvesting and self-defensive modes is associated with a reorganization of light-harvesting complexes. Here we show that despite structural changes, the photosystem II cross-section does not decrease. Our study reveals that the efficiency of energy trapping by the non-photochemical quencher(s) is lower than the efficiency of energy capture by the reaction centres. Consequently, the photoprotective mechanism works effectively for closed rather than open centres. This type of defence preserves the exceptional efficiency of electron transport in a broad range of light intensities, simultaneously ensuring high photosynthetic productivity and, under hazardous light conditions, sufficient photoprotection for both the reaction centre and the light-harvesting pigments of the antenna.

  11. Solar ultraviolet radiation in Africa: a systematic review and critical evaluation of the health risks and use of photoprotection.

    Science.gov (United States)

    Lucas, Robyn M; Norval, Mary; Wright, Caradee Y

    2016-01-01

    Most information on the harmful health effects of solar ultraviolet radiation (UVR) has been obtained in populations in which the majority has fair skin. Here a systematic review of evidence on diseases related to solar UVR in Africa was undertaken, and the appropriateness of effective photoprotection for these people considered. There are few population-based studies on UV-induced skin cancers (melanoma, squamous and basal cell carcinomas) in Africa, although limited reports indicated that they occur, even in people with deeply pigmented skin. The incidence of melanoma is particularly high in the white population living in the Western Cape of South Africa and has increased significantly in recent years. Cataract is extremely common in people of all skin colours and is a frequent cause of blindness, particularly in the elderly. For both skin cancer and cataract, the proportion of the disease risk that is attributable to exposure to solar UVR in African populations, and therefore the health burden caused by UV irradiation is unclear. There was little published information on the use of sun protection in Africa. The potential disease burden attributable to solar UVR exposure of Africans is high, although accurate data to quantify this are sparse. Information is required on the incidence, prevalence and mortality for the range of UV-related diseases in different populations living throughout Africa. Photoprotection is clearly required, at least for those subpopulations at particularly high risk, but may be limited by cost and cultural acceptability.

  12. Diverse mechanisms for photoprotection in photosynthesis. Dynamic regulation of photosystem II excitation in response to rapid environmental change.

    Science.gov (United States)

    Derks, Allen; Schaven, Kristin; Bruce, Doug

    2015-01-01

    Photosystem II (PSII) of photosynthesis catalyzes one of the most challenging reactions in nature, the light driven oxidation of water and release of molecular oxygen. PSII couples the sequential four step oxidation of water and two step reduction of plastoquinone to single photon photochemistry with charge accumulation centers on both its electron donor and acceptor sides. Photon capture, excitation energy transfer, and trapping occur on a much faster time scale than the subsequent electron transfer and charge accumulation steps. A balance between excitation of PSII and the use of the absorbed energy to drive electron transport is essential. If the absorption of light energy increases and/or the sink capacity for photosynthetically derived electrons decreases, potentially deleterious side reactions may occur, including the production of reactive oxygen species. In response, a myriad of fast (second to minutes timescale) and reversible photoprotective mechanisms are observed to regulate PSII excitation when the environment changes more quickly than can be acclimated to by gene expression. This review compares the diverse photoprotective mechanisms that are used to dissipate (quench) PSII excitation within the antenna systems of higher land plants, green algae, diatoms, and cyanobacteria. The molecular bases of how PSII excitation pressure is sensed by the antenna system and how the antenna then reconfigures itself from a light harvesting to an energy dissipative mode are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Seasonal, sex- and plant size-related effects on photoinhibition and photoprotection in the dioecious Mediterranean dwarf palm, Chamaerops humilis

    Directory of Open Access Journals (Sweden)

    Melanie Morales

    2016-07-01

    Full Text Available In Mediterranean-type ecosystems plants are exposed to several adverse environmental conditions throughout the year, ranging from drought stress during the warm and dry summers to chilling stress due to the typical drop in temperatures during winters. Here we evaluated the ecophysiological response, in terms of photoinhibition and photoprotection, of the dioecious Mediterranean palm, Chamaerops humilis to seasonal variations in environmental conditions. Furthermore, we considered as well the influence of plant size, maturity and sexual dimorphism. Results showed evidence of winter photoinhibition, with a marked decrease of the Fv/Fm ratio below 0.7 between January and March, which was coincident with the lowest temperatures. During this period, the de-epoxidation state of the xanthophyll cycle and zeaxanthin levels increased, which might serve as a photoprotection mechanism, owing the full recovery from winter photoinhibition during spring. Furthermore, mature plants showed lower chlorophyll levels and higher β-carotene levels per unit of chlorophyll than juvenile plants, and females displayed lower leaf water contents and higher photoinhibition than males during summer, probably due to increased reproductive effort of females. However, neither low temperatures during winter nor reproductive events in females during the summer led to irreversible damage to the photosynthetic apparatus. We conclude that (i the Mediterranean dwarf palm, C. humilis, suffers from photoinhibition during winter, but this is transient and does not lead to irreversible damage, and (ii females from this plant species are more sensitive than males to photoinhibition during reproductive events.

  14. Leaf Age-Dependent Photoprotective and Antioxidative Response Mechanisms to Paraquat-Induced Oxidative Stress in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Julietta Moustaka

    2015-06-01

    Full Text Available Exposure of Arabidopsis thaliana young and mature leaves to the herbicide paraquat (Pq resulted in a localized increase of hydrogen peroxide (H2O2 in the leaf veins and the neighboring mesophyll cells, but this increase was not similar in the two leaf types. Increased H2O2 production was concomitant with closed reaction centers (qP. Thirty min after Pq exposure despite the induction of the photoprotective mechanism of non-photochemical quenching (NPQ in mature leaves, H2O2 production was lower in young leaves mainly due to the higher increase activity of ascorbate peroxidase (APX. Later, 60 min after Pq exposure, the total antioxidant capacity of young leaves was not sufficient to scavenge the excess reactive oxygen species (ROS that were formed, and thus, a higher H2O2 accumulation in young leaves occurred. The energy allocation of absorbed light in photosystem II (PSII suggests the existence of a differential photoprotective regulatory mechanism in the two leaf types to the time-course Pq exposure accompanied by differential antioxidant protection mechanisms. It is concluded that tolerance to Pq-induced oxidative stress is related to the redox state of quinone A (QA.

  15. Fotoproteção e exercício físico Photoprotection and physical exercise

    Directory of Open Access Journals (Sweden)

    Kátia Sheylla Malta Purim

    2010-06-01

    Full Text Available As medidas de fotoproteção são divulgadas como procedimentos essenciais na prevenção de doenças cutâneas e manutenção da saúde e beleza. Os exercícios físicos regulares também são indicados para alcançar o estilo de vida saudável; no entanto, a prática esportiva expõe a maior radiação solar. O objetivo deste artigo é revisar as medidas fotoprotetoras na prevenção dos danos causados pelo Sol na pele dos desportistas. Abordam-se o histórico da fotoproteção, o espectro eletromagnético, os efeitos das radiações e os riscos de exposição durante as atividades físicas. Implementar estratégias, como a escolha do horário, local, roupas e acessórios, complementados pelo uso de filtros solares, minimizam os riscos decorrentes das radiações ultravioletas A e B (UVA e UVB durante a prática esportiva ao ar livre. Dentre os produtos disponíveis no mercado, devem-se preferir aqueles que ofereçam segurança, ampla proteção, boa cosmética, estabilidade química em diferentes condições de calor e umidade, fotoestabilidade e baixo custo. O atleta deve ser orientado pelos profissionais da área da saúde sobre os riscos inerentes às suas atividades cotidianas e esportivas. O autoexame de pele é parte essencial na prevenção dos problemas dermatológicos, pois auxilia na detecção precoce. O futuro da fotoproteção no esporte está no investimento em medidas educativas desde a infância, reduzindo assim os danos solares cumulativos. A exposição solar deve ocorrer de modo cauteloso e com o mínimo de sequelas, mediante comportamento de fotoproteção, para proporcionar melhor qualidade de vida.Photoprotection measures are reported as crucial procedures in the prevention of skin disorders and health and beauty maintenance. Although regular physical exercises are also recommended to attain a healthy lifestyle, sports activities expose one to increased sun radiation. The aim of this article is to review photoprotection

  16. Evaluation of fructans in various fresh and stewed fruits by high-performance anion-exchange chromatography with pulsed amperometric detection.

    Science.gov (United States)

    L'homme, C; Peschet, J L; Puigserver, A; Biagini, A

    2001-06-22

    Fructans are food-grade non-digestible carbohydrates that exert beneficial nutritional effects. Their characterization and quantification is required for food-labeling purposes. We describe the suitability of high-performance anion-exchange chromatography coupled with pulsed amperometric detection for the identification and quantification of fructans in fresh fruits (various apple and pear cultivars, plum, banana) as well as in commercial stewed fruits obtained from a local manufacturer. After extraction with water and appropriate filtration, inulobiose [beta-D-Fru-(2-->1)-beta-D-fructofuranoside; F2], 1-kestose [beta-D-Fru-(2-->1)2-alpha-D-glucopyranoside; GF2] and nystose [beta-D-Fru-(2-->1)3-alpha-D-glucopyranoside; GF3] were completely separated in a single 36-min run using a Dionex CarboPac PA 100 column and the new quadruple-potential waveform, originally tailored for oligosaccharide separation. No measurable amounts of F3 and GF4 were detected within the group of studied fruit products. Peak identification was realized using standards. The method is easy, reproducible, and sensitive since as little as 28 microg of sugar per gram dry matter can be quantified. Banana and plum are the varieties containing the highest levels of fructans (about 6000 microg per gram dry matter). The maturity of the fruit appears to have a great influence on the level of GF2. Samples of apple-banana stewed fruits contained the highest total fructan concentration (about 700 microg per gram dry matter). Accurate quantification of fructans will allow more precise nutritional formulation and diet selection for higher fructan consumption.

  17. Arsenic speciation based on ion exchange high-performance liquid chromatography hyphenated with hydride generation atomic fluorescence and on-line UV photo oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Bin He; Jiang Gui-bin; Xu Xiao-bai [Chinese Academy of Scinces, Beijing (China). Research Center for Eco-Environmental Sciences

    2000-12-01

    An on-line method capable of the separation of arsenic species was developed for the speciation of arsenite As(III), arsenate As(V), monomethylarsenic (MMA) and dimethylarsenic acid (DMA) in biological samples. The method is based on the combination of high-performance liquid chromatograph (HPLC) for separation, UV photo oxidation for sample digestion and hydride generation atomic fluorescence spectrometry (HGAFS) for sensitive detection. The best separation results were obtained with an anion-exchange AS11 column protected by an AG11 guard column, and gradient elution with NaH{sub 2}PO{sub 4} and water as mobile phase. The on-line UV photo oxidation with 1.5% K{sub 2}S{sub 2}O{sub 8} in 0.2 mol L{sup -1} NaOH in an 8 m PTFE coil for 40 s ensures the digestion of organoarsenic compounds. Detection limits for the four species were in the range of 0.11-0.15 ng (20 {mu}L injected). Procedures were validated by analysis of the certified reference materials GBW09103 freeze-dried human urine and the results were in good agreement with the certified values of total arsenic concentration. The method has been successfully applied to speciation studies of blood arsenic species with no need of sample pretreatment. Speciation of arsenic in blood samples collected from two patients after the ingestion of realgar-containing drug reveals slight increase of arsenite and DMA, resulting from the digestion of realgar. (orig.)

  18. Serial tempering without exchange.

    Science.gov (United States)

    Nymeyer, Hugh

    2010-09-21

    Serial tempering is a computational method that turns the temperature T (or more generally any independent λ parameter) into a dynamical variable. It is shown that, under conditions for which this variable is fast, serial tempering is equivalent to the umbrella sampling method with a single effective potential. This equivalence is demonstrated using both a small one-dimensional system and a small solvated peptide. The suggestion is then made to replace the serial tempering protocol with the equivalent umbrella sampling calculation. This approach, serial tempering without exchange (STeWiE), has the same performance as serial tempering in the limit that exchanges are frequent, is simpler to implement, and has fewer adjustable parameters than conventional serial tempering. The equivalence of serial tempering and STeWiE also provides a convenient route for estimating and optimizing the performance of serial tempering simulations and other generalized-ensemble methods.

  19. Next Generation Microchannel Heat Exchangers

    CERN Document Server

    Ohadi, Michael; Dessiatoun, Serguei; Cetegen, Edvin

    2013-01-01

    In Next Generation Microchannel Heat Exchangers, the authors’ focus on the new generation highly efficient heat exchangers and presentation of novel data and technical expertise not available in the open literature.  Next generation micro channels offer record high heat transfer coefficients with pressure drops much less than conventional micro channel heat exchangers. These inherent features promise fast penetration into many mew markets, including high heat flux cooling of electronics, waste heat recovery and energy efficiency enhancement applications, alternative energy systems, as well as applications in mass exchangers and chemical reactor systems. The combination of up to the minute research findings and technical know-how make this book very timely as the search for high performance heat and mass exchangers that can cut costs in materials consumption intensifies.

  20. Segmented heat exchanger

    Science.gov (United States)

    Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron; Timmons, Kristine Ann

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  1. CFD Simulation of Hydrodynamic and Thermal Performance of a Micro Heat Exchanger Simulation numérique par CFD de l’hydrodynamique et des performances thermiques d’un micro échangeur de chaleur

    Directory of Open Access Journals (Sweden)

    Nastoll W.

    2010-10-01

    Full Text Available To evaluate the performances and limitations of compact heat exchanger with micro-structured plates, CFD simulations of hydrodynamics and thermal transfers have been performed inside a commercial micro heat exchanger from IMM operated in liquid/liquid flows. The hydrodynamic results show that the flow rate distribution over the plates is rather homogeneous with some velocity gradient at the channel inlet due to inertial effect in the distributor. Fluid temperature profiles are both influenced by convective transfer in the channels and in the distributing/collecting sections and by conductive transfer through the metal wall at the plate periphery especially at low flow rates. Due to undesired heat transfer by conduction, the fraction of heat power really transferred inside the channels varies from 75 to 85% in counter current flow configuration and between 35 and 70% in co-current flow configuration. Computational results are successfully compared to 2D experimental temperature profiles measured inside the heat exchanger. Pour évaluer les performances et les limitations d’un échangeur thermique compact composé de plaques micro-structurées, des simulations CFD de l’hydrodynamique et des transferts thermiques ont été effectués en écoulement liquide/liquide pour un micro-échangeur commercialisé par l’IMM. Les résultats de la simulation hydrodynamique montrent que la distribution des flux de l’écoulement liquide est plutôt homogène avec quelques gradients de vitesses à l’entrée des canaux à cause d’effets inertiels dans le distributeur. Les profils de température sont influencés à la fois par les transferts thermiques par convection dans les canaux et dans les zones de distribution et de collecte de l’écoulement et également par les transferts par conduction aux travers des parois métalliques situées entre les canaux et à la périphérie de la zone micro-structurée, en particulier pour les faibles d

  2. Chemical exchange program analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Waffelaert, Pascale

    2007-09-01

    As part of its EMS, Sandia performs an annual environmental aspects/impacts analysis. The purpose of this analysis is to identify the environmental aspects associated with Sandia's activities, products, and services and the potential environmental impacts associated with those aspects. Division and environmental programs established objectives and targets based on the environmental aspects associated with their operations. In 2007 the most significant aspect identified was Hazardous Materials (Use and Storage). The objective for Hazardous Materials (Use and Storage) was to improve chemical handling, storage, and on-site movement of hazardous materials. One of the targets supporting this objective was to develop an effective chemical exchange program, making a business case for it in FY07, and fully implementing a comprehensive chemical exchange program in FY08. A Chemical Exchange Program (CEP) team was formed to implement this target. The team consists of representatives from the Chemical Information System (CIS), Pollution Prevention (P2), the HWMF, Procurement and the Environmental Management System (EMS). The CEP Team performed benchmarking and conducted a life-cycle analysis of the current management of chemicals at SNL/NM and compared it to Chemical Exchange alternatives. Those alternatives are as follows: (1) Revive the 'Virtual' Chemical Exchange Program; (2) Re-implement a 'Physical' Chemical Exchange Program using a Chemical Information System; and (3) Transition to a Chemical Management Services System. The analysis and benchmarking study shows that the present management of chemicals at SNL/NM is significantly disjointed and a life-cycle or 'Cradle-to-Grave' approach to chemical management is needed. This approach must consider the purchasing and maintenance costs as well as the cost of ultimate disposal of the chemicals and materials. A chemical exchange is needed as a mechanism to re-apply chemicals on site. This

  3. An investigation of the predictors of photoprotection and UVR dose to the face in patients with XP: a protocol using observational mixed methods.

    Science.gov (United States)

    Walburn, Jessica; Sarkany, Robert; Norton, Sam; Foster, Lesley; Morgan, Myfanwy; Sainsbury, Kirby; Araújo-Soares, Vera; Anderson, Rebecca; Garrood, Isabel; Heydenreich, Jakob; Sniehotta, Falko F; Vieira, Rute; Wulf, Hans Christian; Weinman, John

    2017-08-21

    Xeroderma pigmentosum (XP) is a rare genetic condition caused by defective nucleotide excision repair and characterised by skin cancer, ocular and neurological involvement. Stringent ultraviolet protection is the only way to prevent skin cancer. Despite the risks, some patients' photoprotection is poor, with a potentially devastating impact on their prognosis. The aim of this research is to identify disease-specific and psychosocial predictors of photoprotection behaviour and ultraviolet radiation (UVR) dose to the face. Mixed methods research based on 45 UK patients will involve qualitative interviews to identify individuals' experience of XP and the influences on their photoprotection behaviours and a cross-sectional quantitative survey to assess biopsychosocial correlates of these behaviours at baseline. This will be followed by objective measurement of UVR exposure for 21 days by wrist-worn dosimeter and daily recording of photoprotection behaviours and psychological variables for up to 50 days in the summer months. This novel methodology will enable UVR dose reaching the face to be calculated and analysed as a clinically relevant endpoint. A range of qualitative and quantitative analytical approaches will be used, reflecting the mixed methods (eg, cross-sectional qualitative interviews, n-of-1 studies). Framework analysis will be used to analyse the qualitative interviews; mixed-effects longitudinal models will be used to examine the association of clinical and psychosocial factors with the average daily UVR dose; dynamic logistic regression models will be used to investigate participant-specific psychosocial factors associated with photoprotection behaviours. This research has been approved by Camden and King's Cross Research Ethics Committee 15/LO/1395. The findings will be published in peer-reviewed journals and presented at national and international scientific conferences. © Article author(s) (or their employer(s) unless otherwise stated in the text of

  4. The impact of cold on photosynthesis in genotypes of Coffea spp.--photosystem sensitivity, photoprotective mechanisms and gene expression.

    Science.gov (United States)

    Batista-Santos, P; Lidon, F C; Fortunato, A; Leitão, A E; Lopes, E; Partelli, F; Ribeiro, A I; Ramalho, J C

    2011-05-15

    Environmental constraints disturb plant metabolism and are often associated with photosynthetic impairments and yield reductions. Among them, low positive temperatures are of up most importance in tropical plant species, namely in Coffea spp. in which some acclimation ability has been reported. To further explain cold tolerance, the impacts on photosynthetic functioning and the expression of photosynthetic-related genes were analyzed. The experiments were carried out along a period of slow cold imposition (to allow acclimation), after chilling (4°C) exposure and in the following rewarming period, using 1.5-year-old coffee seedlings of 5 genotypes with different cold sensitivity: Coffea canephora cv. Apoatã, Coffea arabica cv. Catuaí, Coffea dewevrei and 2 hybrids, Icatu (C. arabica×C. canephora) and Piatã (C. dewevrei×C. arabica). All genotypes suffered a significant leaf area loss only after chilling exposure, with Icatu showing the lowest impact, a first indication of a higher cold tolerance, contrasting with Apoatã and C. dewevrei. During cold exposure, net photosynthesis and Chl a fluorescence parameters were strongly affected in all genotypes, but stomatal limitations were not detected. However, the extent of mesophyll limitation, reflecting regulatory mechanisms and/or damage, was genotype dependent. Overnight retention of zeaxanthin was common to Coffea genotypes, but the accumulation of photoprotective pigments was highest in Icatu. That down-regulated photochemical events but efficiently protected the photosynthetic structures, as shown, e.g., by the lowest impacts on A(max) and PSI activity and the strongest reinforcement of PSII activity, the latter possibly reflecting the presence of a photoprotective cycle around PSII in Icatu (and Catuaí). Concomitant to these protection mechanisms, Icatu was the sole genotype to present simultaneous upregulation of caCP22, caPI and caCytf, related to, respectively, PSII, PSI and to the complex Cytb(6)/f

  5. Performance Comparison of Relational and Native-XML Databases using the Semantics of the Land Command and Control Information Exchange Data Model (LC2IEDM)

    Science.gov (United States)

    2005-09-01

    MIP’s Land Command and Control Information Exchange Data Model (LC2IEDM), it is feasible to compare the syntactic strength of human-readable XML documents with the semantics of LC2IEDM as used within a relational database.

  6. Arsenic and Nitrate Removal from Drinking Water by Ion Exchange U.S. EPA Demonstration Project at Vale, OR - Final Performance Evaluation Report

    Science.gov (United States)

    As part of the EPA Arsenic Removal Technology Demonstration Program, a 540-gal/min (gpm) ion exchange (IX) system proposed by Kinetico was selected for demonstration at Vale, OR to remove arsenic and nitrate from a groundwater supply to meet their respective maximum contaminant l...

  7. High-Performance Liquid Chromatography of Nucleobases, Nucleosides and Nucleotides : II. Mobile Phase Composition for the Separation of Charged Solutes by Ion-Exchange Chromatography

    NARCIS (Netherlands)

    Haastert, Peter J.M. van

    1981-01-01

    The polarity, pH, ion concentration and polarity of the buffer ions of the mobile phase were modified systematically in order to find optimal conditions for the separation of nucleobases, nucleosides and nucleotides by ion-exchange chromatography. The effects of these mobile phase parameters on the

  8. Non-controlling interests, financial performance and the equity of groups. An empirical study of groups listed on the Warsaw Stock Exchange 

    Directory of Open Access Journals (Sweden)

    Radosław Ignatowski

    2015-11-01

    Full Text Available The purpose of this article is to (a analyze IFRS requirements for the recognition and presentation of non-controlling (minority interests in consolidated financial statements in relation to theoretical concepts of consolidation of financial statements, and (b assess the share and importance of non-controlling inter-ests in financial performance and the equity of the groups of companies in practice. For the purpose of the article, selected scientific methods have been used, including: descriptive and analytical ones (for analyzing the theoretical concepts and IFRS requirements, critical analysis, especial-ly used for the literature review, and for the assessment of practice: primary empirical research methods, and quantitative methods, including descriptive statistics, nonparametric tests and correlation analysis. The empirical material collected was used to verify several hypotheses related to non-controlling interests of the groups whose parents are registered in Poland and whose securities are traded on a regulated, Polish capital market (Warsaw Stock Exchange. The empirical evidence is that non-controlling interests represent a very small part of group’s equity (taking the mean of about 3.5%, but the median below 1% and obviously, they are significantly lower than the share of majority interests. Their deviation among the different classes of companies (big, small and banks is negligible. Slightly higher is the share of minority interests in the group’s net profit and total comprehensive income. However, no significant difference is to be found between the shares of non-controlling interests in the group’s equity, net profit and total comprehensive income. Overall, shares of majority (minority interests in a group’s income are in line with their shares in the group’s equity. The hypothesis on comparable returns on non-controlling and majority interests (in terms of ROE cannot be rejected if both net profit and losses are considered

  9. Non-controlling interests, financial performance and the equity of groups. An empirical study of groups listed on the Warsaw Stock Exchange

    Directory of Open Access Journals (Sweden)

    Radosław Ignatowski

    2015-09-01

    Full Text Available The purpose of this article is to (a analyze IFRS requirements for the recognition and presentation of non-controlling (minority interests in consolidated financial statements in relation to theoretical concepts of consolidation of financial statements, and (b assess the share and importance of non-controlling inter-ests in financial performance and the equity of the groups of companies in practice.For the purpose of the article, selected scientific methods have been used, including: descriptive and analytical ones (for analyzing the theoretical concepts and IFRS requirements, critical analysis, especial-ly used for the literature review, and for the assessment of practice: primary empirical research methods, and quantitative methods, including descriptive statistics, nonparametric tests and correlation analysis. The empirical material collected was used to verify several hypotheses related to non-controlling interests of the groups whose parents are registered in Poland and whose securities are traded on a regulated, Polish capital market (Warsaw Stock Exchange. The empirical evidence is that non-controlling interests represent a very small part of group’s equity (taking the mean of about 3.5%, but the median below 1% and obviously, they are significantly lower than the share of majority interests. Their deviation among the different classes of companies (big, small and banks is negligible. Slightly higher is the share of minority interests in the group’s net profit and total comprehensive income. However, no significant difference is to be found between the shares of non-controlling interests in the group’s equity, net profit and total comprehensive income. Overall, shares of majority (minority interests in a group’s income are in line with their shares in the group’s equity. The hypothesis on comparable returns on non-controlling and majority interests (in terms of ROE cannot be rejected if both net profit and losses are considered

  10. Fault-Tolerant Heat Exchanger

    Science.gov (United States)

    Izenson, Michael G.; Crowley, Christopher J.

    2005-01-01

    A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

  11. Ultrasound-assisted extraction of bioactive compounds from palm pressed fiber with high antioxidant and photoprotective activities.

    Science.gov (United States)

    Dal Prá, Valéria; Lunelli, Felipe C; Vendruscolo, Raquel Guidetti; Martins, Rafael; Wagner, Roger; Lazzaretti, Ayres P; Freire, Denise M Guimarães; Alexandri, Maria; Koutinas, Apostolis; Mazutti, Marcio A; da Rosa, Marcelo Barcellos

    2017-05-01

    This work is focused on the optimization of the ultrasound-assisted extraction of antioxidant compounds with photoprotective effect from palm pressed fiber. The influence of ultrasound intensity and pulse cycle was investigated by means of a central composite rotational design. The optimized condition was ultrasound intensity of 120W.cm(-2) and pulse factor of 0.4, yielding 3.24wt%. Compounds such as fatty acids, β-sitosterol, α-tocopherol, squalene, total phenolics and carotene were identified. The extract presented antioxidant activity towards synthetic (2,2-diphenyl-1-picrylhydrazyl - DPPH, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) - ABTS) and biological radicals (Hydroxyl - OH), besides a sun protection factor of 15.01. Polar extracts from palm pressed fiber are promising candidates for use in cosmetic and pharmaceutical formulation since they present high antioxidant activity towards different radicals, combined with the high sun protection factor. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Studies Towards Obtaining a Photoprotective Dermo-cosmetic Complex Product With Natura Extracts of Inorganic and Organic Substances

    Directory of Open Access Journals (Sweden)

    Ancuţa Fiţa

    2010-06-01

    Full Text Available Photoprotective products are considered borderline between
    cosmetics and pharmaceuticals due to physiological implications they have on skin health considering the environmental changes (radiations, global warming, and the diminished ozone layer and due to the high demands regarding the balance between the e±cacy and the safety of the consumer. The studies we have carried out in this paper consist in the following: selection of the excipients and active ingredients (organic and inorganic filter and/or screen substances, natural products, antioxidants and the use of a proper technological process for obtaining a dermo-cosmetic product having a good physical and chemical stability, as well as suitable organoleptic and rheological properties in order to ensure the innocuity and pleasant administrating features.

  13. Development and photoprotective effect of a sunscreen containing the antioxidants Spirulina and dimethylmethoxy chromanol on sun-induced skin damage.

    Science.gov (United States)

    Souza, Carla; Campos, Patrícia M B G Maia

    2017-06-15

    The literature claims that incorporation of antioxidants into sunscreens provides additional skin photoprotection by scavenging free radicals formed due to sun radiation, but there are limited in vivo studies that support this hypothesis. This study aims to examine whether addition of antioxidants to a broad-spectrum sunscreen increases its photoprotective effect in real-use conditions. Sunscreen formulations composed of stable UV filters (Tinosorb® S, Tinosorb® M, Uvinul® APlus, and Uvinul® T150) alone or in combination with antioxidants (Spirulina and dimethylmethoxy chromanol-loaded solid lipid nanoparticles) were developed and their appearance, odor, rheological behavior, Sun Protection Factor (SPF), and UVA protection were analyzed. Next, it was conducted a 3-month, single-blind clinical study with 44 healthy subjects (30-50years). Before and 28, 54, and 84days after twice-daily self application of the sunscreens on the face, the stratum corneum water content, transepidermal water loss, dermis echogenicity, and skin elasticity and pigmentation were measured. At the end of the study period, the volunteers answered a questionnaire containing terms related to sensory characteristics of the formulations. All formulations were stable and exhibited non-Newtonian and pseudoplastic behavior, in vivo SPF 30, and good UVA protection. Antioxidant supplementation to the sunscreen formulation significantly improved the skin pigmentation, the collagen degradation on the dermis and thereby the skin net elasticity after 84days of treatment compared to the sunscreen alone. Concerning safety, all formulations were considered non-irritant according to the sensorial analyses, whose results agreed with the clinical study findings. Copyright © 2017. Published by Elsevier B.V.

  14. Skin photoprotective and antiageing effects of a combination of rosemary (Rosmarinus officinalis and grapefruit (Citrus paradisi polyphenols

    Directory of Open Access Journals (Sweden)

    Vincenzo Nobile

    2016-07-01

    Full Text Available Background: Plant polyphenols have been found to be effective in preventing ultraviolet radiation (UVR-induced skin alterations. A dietary approach based of these compounds could be a safe and effective method to provide a continuous adjunctive photoprotection measure. In a previous study, a combination of rosemary (Rosmarinus officinalis and grapefruit (Citrus paradisi extracts has exhibited potential photoprotective effects both in skin cell model and in a human pilot trial. Objective: We investigated the efficacy of a combination of rosemary (R. officinalis and grapefruit (C. paradisi in decreasing the individual susceptibility to UVR exposure (redness and lipoperoxides and in improving skin wrinkledness and elasticity. Design: A randomised, parallel group study was carried out on 90 subjects. Furthermore, a pilot, randomised, crossover study was carried out on five subjects. Female subjects having skin phototype from I to III and showing mild to moderate chrono- or photoageing clinical signs were enrolled in both studies. Skin redness (a* value of CIELab colour space after UVB exposure to 1 minimal erythemal dose (MED was assessed in the pilot study, while MED, lipoperoxides (malondialdehyde skin content, wrinkle depth (image analysis, and skin elasticity (suction and elongation method were measured in the main study. Results: Treated subjects showed a decrease of the UVB- and UVA-induced skin alterations (decreased skin redness and lipoperoxides and an improvement of skin wrinkledness and elasticity. No differences were found between the 100 and 250 mg extracts doses, indicating a plateau effect starting from 100 mg extracts dose. Some of the positive effects were noted as short as 2 weeks of product consumption. Conclusions: The long-term oral intake of Nutroxsun™ can be considered to be a complementary nutrition strategy to avoid the negative effects of sun exposure. The putative mechanism for these effects is most likely to take place

  15. Skin photoprotective and antiageing effects of a combination of rosemary (Rosmarinus officinalis) and grapefruit (Citrus paradisi) polyphenols

    Science.gov (United States)

    Nobile, Vincenzo; Michelotti, Angela; Cestone, Enza; Caturla, Nuria; Castillo, Julián; Benavente-García, Obdulio; Pérez-Sánchez, Almudena; Micol, Vicente

    2016-01-01

    Background Plant polyphenols have been found to be effective in preventing ultraviolet radiation (UVR)-induced skin alterations. A dietary approach based of these compounds could be a safe and effective method to provide a continuous adjunctive photoprotection measure. In a previous study, a combination of rosemary (Rosmarinus officinalis) and grapefruit (Citrus paradisi) extracts has exhibited potential photoprotective effects both in skin cell model and in a human pilot trial. Objective We investigated the efficacy of a combination of rosemary (R. officinalis) and grapefruit (C. paradisi) in decreasing the individual susceptibility to UVR exposure (redness and lipoperoxides) and in improving skin wrinkledness and elasticity. Design A randomised, parallel group study was carried out on 90 subjects. Furthermore, a pilot, randomised, crossover study was carried out on five subjects. Female subjects having skin phototype from I to III and showing mild to moderate chrono- or photoageing clinical signs were enrolled in both studies. Skin redness (a* value of CIELab colour space) after UVB exposure to 1 minimal erythemal dose (MED) was assessed in the pilot study, while MED, lipoperoxides (malondialdehyde) skin content, wrinkle depth (image analysis), and skin elasticity (suction and elongation method) were measured in the main study. Results Treated subjects showed a decrease of the UVB- and UVA-induced skin alterations (decreased skin redness and lipoperoxides) and an improvement of skin wrinkledness and elasticity. No differences were found between the 100 and 250 mg extracts doses, indicating a plateau effect starting from 100 mg extracts dose. Some of the positive effects were noted as short as 2 weeks of product consumption. Conclusions The long-term oral intake of Nutroxsun™ can be considered to be a complementary nutrition strategy to avoid the negative effects of sun exposure. The putative mechanism for these effects is most likely to take place through the

  16. Totalization Data Exchange (TDEX)

    Data.gov (United States)

    Social Security Administration — The Totalization Data Exchange (TDEX) process is an exchange between SSA and its foreign country partners to identify deaths of beneficiaries residing abroad. The...

  17. Numerical heat transfer studies of the fatty acids for different heat exchanger materials on the performance of a latent heat storage system

    Energy Technology Data Exchange (ETDEWEB)

    Atul Sharma; Lee Dong Won; Jun Un Park [Korea Institute of Energy Research, Daejeon (Korea). Solar Thermal Research Centre; Buddhi, D. [Devi Ahilya University, Indore (India). Thermal Energy Storage Laboratory

    2005-11-01

    Theoretical investigations of fatty acids as a phase change material (PCM) for energy storage system have been conducted in this study. The selected fatty acids were capric acid, lauric acid, myristic acid, palmitic acid and stearic acid. For the two-dimensional simulation model based on the enthalpy approach, calculations have been made for the melt fraction with conduction only. Glass, stainless steel, tin, aluminium mixed, aluminium and copper were used as heat exchanger materials in the numerical calculations. Theoretical results show that capric acid was found good compatibility with latent heat storage system. The large value of thermal conductivity of heat exchanger materials did not make significant contribution on the melt fraction. (author)

  18. Study of a Multi-Phase Hybrid Heat Exchanger-Reactor (HEX Reactor): Part 2 - Numerical Prediction of Thermal Performance (Postprint)

    Science.gov (United States)

    2014-01-01

    working fluids , and PHE configurations. 15. SUBJECT TERMS ammonium carbamate, HEX Reactor, thermal management, plate heat exchanger, reacting flow...energy in bulk AC salt. Schmidt [7] proposed forming reacting slur- ry by immersing small AC salt particles in a non -reactive heat transfer fluid (HTF) to...secondary flows characteristic of PHEs. Negligible conduction heat transfer in the axial direction. Fluids are Newtonian and incompressible. In accordance

  19. Dicationic imidazolium ionic liquid modified silica as a novel reversed-phase/anion-exchange mixed-mode stationary phase for high-performance liquid chromatography.

    Science.gov (United States)

    Sun, Min; Feng, Juanjuan; Wang, Xiaojiao; Duan, Huimin; Li, Leilei; Luo, Chuannan

    2014-08-01

    A dicationic imidazolium ionic liquid modified silica stationary phase was prepared and evaluated by reversed-phase/anion-exchange mixed-mode chromatography. Model compounds (polycyclic aromatic hydrocarbons and anilines) were separated well on the column by reversed-phase chromatography; inorganic anions (bromate, bromide, nitrate, iodide, and thiocyanate), and organic anions (p-aminobenzoic acid, p-anilinesulfonic acid, sodium benzoate, pathalic acid, and salicylic acid) were also separated individually by anion-exchange chromatography. Based on the multiple sites of the stationary phase, the column could separate 14 solutes containing the above series of analytes in one run. The dicationic imidazolium ionic liquid modified silica can interact with hydrophobic analytes by the hydrophobic C6 chain; it can enhance selectivity to aromatic compounds by imidazolium groups; and it also provided anion-exchange and electrostatic interactions with ionic solutes. Compared with a monocationic ionic liquid functionalized stationary phase, the new stationary phase represented enhanced selectivity owing to more interaction sites. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Experimental investigation of air side heat transfer and fluid flow performances of multi-port serpentine cross-flow mesochannel heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Faisal A.; Dasgupta, Engr Sarbadaman [Dept. of Mechanical, Automotive, and Materials Engineering (MAME), University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4 (Canada); Fartaj, Amir, E-mail: fartaj@uwindsor.ca [Dept. of Mechanical, Automotive, and Materials Engineering (MAME), University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4 (Canada)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Air side heat transfer and flow characteristics of mesochannel cross-flow heat exchanger are studied experimentally. Black-Right-Pointing-Pointer Hot ethylene glycol-water mixture (50:50) at constant mass flow rate is used against varying air flow. Black-Right-Pointing-Pointer Air side heat transfer and fluid flow key parameters such as Nusselt number, Colburn factor, friction factor are obtained. Black-Right-Pointing-Pointer General correlations are proposed for air side heat transfer and fluid flow parameters. - Abstract: Air side force convective heat transfer and flow characteristics of cross-flow mesochannel heat exchanger are investigated experimentally. A series of experiments representing 36 different operating conditions have been conducted on a finned mesochannel heat exchanger through the fully automated dynamic single-phase experimental facility which is capable of handling a wide variety of working fluids in air-to-liquid cross-flow orientation. The mesochannel heat exchanger is made of 15 aluminum slabs with arrays of wavy fins between slabs; 68 one millimeter circular diameter port located at each slab, and the air side frontal area of 304-mm Multiplication-Sign 304-mm. The ethylene glycol-water mixture as the working fluid in the liquid side was forced to flow through mesochannels maintaining constant inlet temperature and flow rate at 74 Degree-Sign C and 0.0345 kg/s respectively whereas the inlet flowing air into the arrays of wavy fins was changed at four different temperature levels from 28 Degree-Sign C to 43 Degree-Sign C. Frontal air velocity was altered in nine steps from 3 m/s to 11 m/s at each temperature level corresponding range of Reynolds number 752 < Re{sub a} < 3165. The air side heat transfer and flow characteristics of mesochannel heat exchanger were evaluated during air heating, and heat transfer and fluid flow correlations were derived accordingly. The air side Nusselt number (Nu{sub a

  1. The effect the effectiveness of the liquid suction heat exchanger to performance of cold storage with refrigerant R22, R404A and R290/R600a

    Science.gov (United States)

    Prayudi, Nurhasanah, Roswati; Diantari, Retno Aita

    2017-01-01

    Storage space requirements with a large refrigeration capacity they use refrigerants types R22 and R404A. This research to develop alternative technologies to meet the needs of storage space with a large refrigeration capacity. Liquid suction subcooling technology is typically used to obtain improve refrigeration effect at vapor compression refrigeration system. Liquid suction heat exchanger subcooling used a type of tube in tube heat exchanger installed between the condenser and the capillary tube before entering the evaporator. Refrigerant used in this research is R22, R404A, and mixture refrigerant R290/R600a [50:50]. In steady state condition with subcooling temperature evaporator with R290/R600a lower reaches -30°C, lower than R404a and R22 is -24°C and -22°C. Liquid suction heat exchanger subcooling effect on ΔTsub. The cooling effect by the mixture refrigerant of R290/R600a greater than R404a and R22, and liquid suction heat exchanger increase refrigeration capacity index (RCI). The average increase in RCI respectively 3.91%, 7.78%, and 11.87%. Work compressor and compressor work index (CWI) with a mixture refrigerant of R290/R600a greater than R404a and R22, the average work compressor and the working compressor index is greatest mixture refrigerant R290/R600a. CWI respectively is an average of 5.68%, 8.82%, and 11.82%. The average COP, their, liquid suction heat exchanger, respectively are 3.38, 3.18 and 2.63. COPRS with a mixture refrigerant of R290/R600a [50:50] is bigger than the R22 and R404a, and the average COPRS is 5:01%, 5.95%, and 7:41%. A mixture refrigerant R290/R600a [50:50] have the same characteristics as R404a, which can be used as a substitute for refrigerant R22 and R404A.

  2. Effect of ligand exchange of Cu{sub 2}ZnSnS{sub 4} nanocrystals on the charge transport and photovoltaic performance of nanostructured depleted bulk heterojunction solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuo-Xi; Zhou, Zheng-Ji, E-mail: zzj@henu.edu.cn; Bai, Bing; Liu, Ming-Hua; Zhou, Wen-Hui; Kou, Dong-Xing; Wu, Si-Xin, E-mail: wusixin@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials of Ministry of Education (China)

    2015-12-15

    Cu{sub 2}ZnSnS{sub 4} (CZTS) nanocrystals combining the advantage of feasible solution-phase synthesis and processing are perceived as promising materials for application in efficient, low-cost photovoltaic technology. Herein, we have got surfactant-free CZTS nanocrystals by a novel ligand exchange method, and the obtained CZTS nanocrystals were deposited onto ZnO nanorod arrays to construct depleted bulk heterojunction solar cell. The all-inorganic CZTS nanocrystal solar cells demonstrated a remarkable improvement in J{sub sc} (from 8.14 to 13.97 mA/cm{sup 2}) and power conversion efficiency (from 1.83 to 3.34 %) compared with surfactant-capped CZTS nanocrystals. Using surface photovoltage spectrum, the influence of ligand exchange of CZTS nanocrystals on the charge transport and photovoltaic performance of the nanostructured CZTS solar cells was discussed.

  3. Liquid droplet heat exchanger studies

    Science.gov (United States)

    Bruckner, A. P.; Hedges, D. E.; Yungster, S.

    1987-01-01

    Recent analytical and experimental investigations of the liquid droplet heat exchanger (LDHX) concept for space power applications are described. The performance of the LDHX is compared to that of a conventional heat exchanger for heat rejection applications in a Brayton cycle, using the mass-specific heat exchanger effectiveness as a figure of merit. It is shown that the LDHX has an order of magnitude advantage over the conventional heat exchanger. Furthermore, significant improvement in cycle efficiency and power to mass ratio is possible. Two-phase flow experiments in a laboratory scale LDHX, using air and water as the two media, show very good agreement with the quasi-one-dimensional model used in the parametric studies.

  4. Performance evaluation of 24 ion exchange materials for removing cesium and strontium from actual and simulated N-Reactor storage basin water

    Energy Technology Data Exchange (ETDEWEB)

    Brown, G.N.; Carson, K.J.; DesChane, J.R.; Elovich, R.J.

    1997-09-01

    This report describes the evaluation of 24 organic and inorganic ion exchange materials for removing cesium and strontium from actual and simulated waters from the 100 Area 105 N-Reactor fuel storage basin. The data described in this report can be applied for developing and evaluating ion exchange pre-treatment process flowsheets. Cesium and strontium batch distribution ratios (K{sub d}`s), decontamination factors (DF), and material loadings (mmol g{sup -1}) are compared as a function of ion exchange material and initial cesium concentration. The actual and simulated N-Basin waters contain relatively low levels of aluminum, barium, calcium, potassium, and magnesium (ranging from 8.33E-04 to 6.40E-05 M), with slightly higher levels of boron (6.63E-03 M) and sodium (1.62E-03 M). The {sup 137}Cs level is 1.74E-06 Ci L-{sup 1} which corresponds to approximately 4.87E-10 M Cs. The initial Na/Cs ratio was 3.33E+06. The concentration of total strontium is 4.45E-06 M, while the {sup 90}Sr radioactive component was measured to be 6.13E-06 Ci L{sup -1}. Simulant tests were conducted by contacting 0.067 g or each ion exchange material with approximately 100 mL of either the actual or simulated N-Basin water. The simulants contained variable initial cesium concentrations ranging from 1.00E-04 to 2.57E- 10 M Cs while all other components were held constant. For all materials, the average cesium K{sub d} was independent of cesium concentration below approximately 1.0E-06 M. Above this level, the average cesium K{sub d} values decreased significantly. Cesium K{sub d} values exceeding 1.0E+07 mL g{sup -1} were measured in the simulated N-Basin water. However, when measured in the actual N-Basin water the values were several orders of magnitude lower, with a maximum of 1.24E+05 mL g{sup -1} observed.

  5. Examining the photoprotection hypothesis for adaxial foliar anthocyanin accumulation by revisiting comparisons of green- and red-leafed varieties of coleus (Solenostemon scutellarioides).

    Science.gov (United States)

    Logan, Barry A; Stafstrom, William C; Walsh, Michael J L; Reblin, Jaret S; Gould, Kevin S

    2015-06-01

    Although plants rely on light to drive energy production via photosynthesis, excess light can be harmful. Plants have evolved photoprotective mechanisms to mitigate this threat, including thermal energy dissipation, the most common form of which involves de-epoxidized constituents of the xanthophyll cycle facilitating the conversion of excess excitation energy to heat. A role in photoprotection has also been proposed for red anthocyanins when they accumulate near the adaxial leaf surface. Here, we compared the response to experimental light stress of a red-leafed (anthocyanin rich) and a green-leafed variety of coleus [Solenostemon scutellarioides (L.) Codd], examining chlorophyll fluorescence emission and pigment composition. After experimentally imposed intense white light, red- and green-leafed coleus exhibited manifestations of light stress (decreased photosystem II quantum efficiency) of a similar magnitude. This, considered alone, could be interpreted as evidence that anthocyanins do not serve a photoprotective role. However, during excess light exposure, the green-leafed variety employed a greater level of thermal energy dissipation and possessed correspondingly higher xanthophyll cycle pool sizes and de-epoxidation states. During exposure to red light, which anthocyanins absorb very poorly, levels of thermal energy dissipation did not differ between coleus varieties. Taken together, our findings suggest that adaxial anthocyanins minimize stress associated with excess light absorption and that the green-leafed variety of coleus compensated for its much lower levels of adaxial anthocyanins by invoking higher levels of energy dissipation. Thus, anthocyanin accumulation should be considered alongside the suite of photoprotective mechanisms employed by photosynthetic tissues.

  6. Trade-Offs Associated with Photoprotective Green Fluorescent Protein Expression as Potential Drivers of Balancing Selection for Color Polymorphism in Reef Corals

    OpenAIRE

    Cathryn Quick; Cecilia D'Angelo; Cecilia D'Angelo; Jörg Wiedenmann; Jörg Wiedenmann

    2018-01-01

    Photodamage of symbiotic algae exposed to thermal stress is involved in mass coral bleaching, a major cause of reef decline. Photoprotection is therefore a vital part of coral stress physiology. Corals produce a variety of green fluorescent protein (GFP)-like proteins, some of which screen the symbiotic algae from excess sun light. Different tissue concentrations of these GFP-like proteins distinguish color morphs that are characteristic for many coral species. The question arises whether the...

  7. Seasonally-induced alterations of some facial signs in Caucasian women and their changes induced by a daily application of a photo-protective product.

    Science.gov (United States)

    Flament, F; Gautier, B; Benize, A-M; Charbonneau, A; Cassier, M

    2017-09-08

    These were two-fold: (i) to assess the possible changes in some facial signs induced in a 6-month period by the periodical shift from winter to summer in Caucasian women and (ii) to appraise the preventive effects of a strong photo-protective product. The facial signs of two cohorts of French women (N= 40 and 42), of comparable ages were graded between winter to summer. One group was left unprotected whereas the other daily applied a strong photo-protective product for 6 months. Facial signs (structural and pigmentation-related) were graded in blind by a panel of 12 experts from photographs taken under standard conditions. A global and focused analysis of the skin colour or dark spots, when present, was carried out through spectro-radiometry under diffuse and standardized visible light, using the L*, a*, b* referential system. The unprotected group showed significant changes in summer as compared to winter on 10 facial signs (two-third of the studied signs) that presented an increased severity, of variable respective amplitude. Five signs among the 10 were particularly and significantly affected by the seasonal transition, of an amplitude above the precision of the grading scale. Three of these five signs concerned structural elements (wrinkles), the two others being related to vascular disorders (redness). These season-induced alterations appear efficiently reduced in the photo-protected group. The colour of the facial skin then appears more homogeneous, less red, less dull, all criteria being quantified by the L*, a*, b* referential system. The comparison with a previous work carried out on Chinese women, through a similar protocol, shows that the photo-protective product brings, in Caucasian women, a more important effect upon structural and vascular features than upon pigmentation disorders, inversely to the results previously observed in Chinese women. The alterations in some facial signs occurring in a 6-month period between winter and summer are confirmed in

  8. Adsorbents/ion exchangers-PVA blend membranes: Preparation, characterization and performance for the removal of Zn{sup 2+} by electrodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Caprarescu, Simona [Politehnica University of Bucharest, Faculty of Applied Chemistry and Materials Science, Inorganic Chemistry, Physical Chemistry and Electrochemistry Department, 1-7 Polizu Street, 011061 Bucharest (Romania); Radu, Anita-Laura, E-mail: raduanita@gmail.com [Polymer Department, National Research and Development Institute for Chemistry and Petrochemistry – ICECHIM, Splaiul Independentei, No. 202, 060021 Bucharest (Romania); Purcar, Violeta; Ianchis, Raluca; Sarbu, Andrei; Ghiurea, Marius; Nicolae, Cristian [Polymer Department, National Research and Development Institute for Chemistry and Petrochemistry – ICECHIM, Splaiul Independentei, No. 202, 060021 Bucharest (Romania); Modrogan, Cristina [Politehnica University of Bucharest, Faculty of Applied Chemistry and Materials Science, Inorganic Substances and Environmental Protection Department, 1-7 Polizu Street, 011061 Bucharest (Romania); Vaireanu, Danut-Ionel [Politehnica University of Bucharest, Faculty of Applied Chemistry and Materials Science, Inorganic Chemistry, Physical Chemistry and Electrochemistry Department, 1-7 Polizu Street, 011061 Bucharest (Romania); Périchaud, Alain [Catalyse, lot 25, Master Park – 116, Bd de la Pomme, 13011 Marseille (France); Ebrasu, Daniela-Ion [National Research & Development Institute for Cryogenics and Isotopic Technologies-ICSI-Rm. Valcea, P.O. Box Raureni 7, 240050 Ramnicu Valcea (Romania)

    2015-02-28

    Highlights: • Removal of Zn{sup 2+} from the wastewater discharged from electroplating processes was studied. • A mini-electrodialysis system and different resin membranes were used. • The electrodialysis experiments were carried out at 25 °C, with and without recirculation. • The EIS measurements were carried out using new stainless steel disk electrodes. • The efficiency of the electrodialysis cell, mass flow, energy consumption was investigated. - Abstract: The present paper was aimed at studying the possibility of zinc (Zn) removal from the wastewater discharged from zinc electroplating processes. In order to save industrial and environmental resources, the concentrated solution could be reused after electrodialysis process. A mini-electrodialysis system with three cylindrical compartments and different membranes containing various resins (Purolite A500 and Hypersol-Macronet MN500) was employed, which can be further applied for the treatment of synthetic effluent which contained zinc ions. The electrodialysis system was operated at constant voltage using different concentrations of synthetic solutions of zinc ions, without and with electrolyte recirculation for 1.5 h. The pH and conductivity of solutions were measured before and after the electrodialysis process occurs. Also the removal ratio (R{sub r}) and mass flow (J) of zinc ions, energy consumption (EC) and current efficiency (CE) were determined. It was found that electrodialysis treatment generated a very low conductivity solution, enabling its reuse as rinse water. According to the obtained results when using a membrane pair with higher ion exchange capacity (IEC) the removal ratio is improved (over 80%). The physico-chemical, structural and mechanical properties of prepared membranes were registered, before and after electrodialysis process takes place, by means of complementary analytical techniques, namely, ion-exchange capacity, water content and thickness measurements. Furthermore

  9. A Structural Equation Model of the Effects of Negative Affectivity, Leader-Member Exchange, and Perceived Job Mobility on In-role and Extra-role Performance: A Chinese Case.

    Science.gov (United States)

    Hui; Law; Chen

    1999-01-01

    In this paper, we contrast the effects of leader-member exchange (LMX) with the effects of perceived job mobility on in-role performance and organizational citizenship behavior (OCB). We further model negative affectivity as the antecedent of both LMX and perceived job mobility and suggest that LMX and perceived job mobility mediated the relationship between negative affectivity and performance. We obtained matching data from supervisor and subordinates in a major battery manufacturing company in southern China. Subordinates provided the negative affectivity, perceived job mobility, and LMX assessment, and their immediate supervisors provided the in-role performance and OCB assessment. Results from a structural equation analysis show that both LMX and perceived job mobility predicted OCB. Instead of being a direct antecedent of OCB, the relationship between negative affectivity and OCB is found to be mediated by LMX and perceived job mobility. Theoretical implications of the results are discussed. Copyright 1999 Academic Press.

  10. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, Kathryn M. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-06

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  11. Maintenance of CERN telephone exchanges

    CERN Multimedia

    2005-01-01

    A maintenance of CERN telephone exchanges will be performed on 21st, 22nd, 23rd, 24th of September from 7 p.m. to 9 p.m. Disturbances or even interruptions of telephony services may occur during this lapse of time. We apology in advance for any inconveniences that this may cause.

  12. Energy Exchange NASA Opening Plenary

    Science.gov (United States)

    Marrs, Rick

    2017-01-01

    Rick Marrs, Deputy Assistant Administrator Office of Strategic Infrastructure NASA Headquarters will be speaking during the 2017 Energy Exchange opening plenary. His presentation showcases the NASA mission, sustainability at NASA, NASA's strategic Sustainability Performance Plan, Existing PV Partnerships, and NASA funded Solar Initiatives at KSC.

  13. In vitro antioxidant and in vivo photoprotective effects of a lyophilized extract of Capparis spinosa L buds.

    Science.gov (United States)

    Bonina, F; Puglia, C; Ventura, D; Aquino, R; Tortora, S; Sacchi, A; Saija, A; Tomaino, A; Pellegrino, M L; de Caprariis, P

    2002-01-01

    The aim of the present study was to evaluate the in vitro antioxidant and in vivo photoprotective activities of a lyophilized extract of Capparis spinosa L. (LECS) obtained by methanolic extraction from the flowering buds of this plant. For the in vitro experiments, LECS was tested employing three different models: (a). bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test); (b). peroxidation, induced by the water-soluble radical initiator 2,2'-azobis(2-amidinopropane) hydrochloride, of mixed dipalmitoylphosphatidylcholine/linoleic acid unilamellar vesicles (LUVs) (LP-LUV test); and (c). UV-induced peroxidation of phosphatidylcholine multilamellar vesicles (UV-IP test). The in vivo antioxidant/radical scavenger activity was assessed by determining the ability of topically applied LECS to reduce UVB-induced skin erythema in healthy human volunteers. From the results obtained in in vitro and in vivo tests, LECS showed a significant antioxidant effect. Furthermore, by chromatographic fractionation and spectroscopic methods, we identified the major constituents of LECS, and particularly some flavonols (kaempferol and quercetin derivatives) and hydroxycinnamic acids (caffeic acid, ferulic acid, p-cumaric acid, and cinnamic acid).

  14. Betalain induction by l-DOPA application confers photoprotection to saline-exposed leaves of Disphyma australe.

    Science.gov (United States)

    Jain, Gagandeep; Schwinn, Kathy E; Gould, Kevin S

    2015-09-01

    The capacity to synthesize betalains has arisen in diverse phylogenetic lineages across the Caryophyllales, and because betalainic plants often grow in deserts, sand dunes, or salt marshes, it is likely that these pigments confer adaptive advantages. However, possible functional roles of foliar betalains remain largely unexplored and are difficult to test experimentally. We adopted a novel approach to examine putative photoprotective roles of betalains in leaves for which chloroplast function has been compromised by salinity. Responses of l-DOPA-treated red shoots of Disphyma australe to high light and salinity were compared with those of naturally red- and green-leafed morphs. Betalain content and tyrosinase activity were measured, and Chl fluorescence profiles and H2 O2 production were compared under white, red or green light. Green leaves lacked tyrosinase activity, but when supplied with exogenous l-DOPA they produced five betacyanins. Both the naturally red and l-DOPA-induced red leaves generated less H2 O2 and showed smaller declines in photosystem II quantum efficiency than did green leaves when exposed to white or green light, although not when exposed to red light. Light screening by epidermal betalains effectively reduces the propensity for photoinhibition and photo-oxidative stress in subjacent chlorenchyma. This may assist plant survival in exposed and saline environments. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  15. Cyclic electron flow plays an important role in photoprotection of tropical trees illuminated at temporal chilling temperature.

    Science.gov (United States)

    Huang, Wei; Zhang, Shi-Bao; Cao, Kun-Fang

    2011-02-01

    Our previous study indicated that PSII is more sensitive to chilling and light stress than PSI in tropical trees, and Erythrophleum guineense is more sensitive to chilling stress than Dalbergia odorifera and Khaya ivorensis, but the underlying physiological mechanisms are unclear. Although recent studies have reported that cyclic electron flow (CEF) plays an important role in photoprotection, the role of CEF in protecting PSI and PSII of tropical tree species remains unclear. We investigated the effect of temporal chilling temperature on energy distribution in PSII, the redox state of P700 and CEF in the above-mentioned tropical evergreen tree species grown in an open field. Our results indicated that the overclosure of PSII reaction centers at chilling temperature led to excess excitation pressure in PSII. At the temporal chilling temperature under low light, PSI acceptor side limitation [Y(NA)] was lower than those at 25°C for all species. Although the effective quantum yield of CEF [Y(CEF)] was not significantly stimulated in E. guineense and K. ivorensis under temporal chilling at low light levels, the ratio of Y(CEF) to the effective quantum yield of PSII [Y(II)] significantly increased. Under chilling conditions Y(CEF)/Y(II) was stimulated much more in K. ivorensis and D. odorifera compared with that in the chilling-sensitive E. guineense. These results suggested that stimulation of Y(CEF)/Y(II) plays an important role in protecting PSI and PSII from photoinhibition caused by chilling stress.

  16. Enhanced biosynthesis of quercetin occurs as A photoprotective measure in Lycopersicon esculentum mill. under Acute UV-B exposure

    Directory of Open Access Journals (Sweden)

    Abhilasha Shourie

    2014-06-01

    Full Text Available Lycopersicon esculentum respond to UV-B by enhanced synthesis of flavonoid quercetin, a strong antioxidant that helps the plants to well acclimatize to UV-B stress. Three weeks old plants of L. esculentum were subjected to acute UV-B irradiation for 20, 40 and 60 minutes daily until 28 days and analyzed for the morphological and biochemical changes. UV-B exposure for 40 and 60 minutes considerably affected the growth and biomass of L. esculentum. The leaves were deformed, developed chlorosis and abscised early as compared to the unexposed plants. Biomass declined by 35% and total chlorophyll decreased by 24.7% due to disintegration of chloroplasts. Enhancement was seen in the content of carotenoids, anthocyanins and total flavonoids by 15, 33.3 and 22.8%, respectively, which was attributed to the photoprotective role of these compounds as potential quenchers of excess excitation energy. Quercetin content decreased on UV-B exposure to 20 and 40 min, and thereafter increased significantly by 5.19% on 60 min of exposure. This pattern probably indicated that the over-expression of genes involved in its biosynthesis such as phenylalanine ammonia lyase (PAL, chalcone synthase (CHS, flavanone 3-hydroxylase (F3H and dihydroflavonol 4-reductase (DFR occurred only after certain threshold exposure (60 min, which could be the strategy for developing tolerance against UV-B stress in L. esculentum.

  17. Does triacylglycerol (TAG) serve a photoprotective function in plant leaves? An examination of leaf lipids under shading and drought.

    Science.gov (United States)

    Marchin, Renée M; Turnbull, Tarryn L; Deheinzelin, Audrey I; Adams, Mark A

    2017-11-01

    Plant survival in many ecosystems requires tolerance of large radiation loads, unreliable water supply and suboptimal soil fertility. We hypothesized that increased production of neutral lipids (triacylglycerols, TAGs) in plant leaves is a mechanism for dissipating excess radiation energy. In a greenhouse experiment, we combined drought and shade treatments and examined responses among four species differing in life form, habitat, and drought- and shade-tolerance. We also present a lipid extraction protocol suitable for sclerophyllous leaves of native Australian trees (e.g. Acacia, Eucalyptus). Fluorescence measurements indicated that plants exposed to full sunlight experienced mild photoinhibition during our experiment. Accumulation of TAGs did not follow photosynthetic capacity, but instead, TAG concentration increased with non-photochemical quenching. This suggests that plants under oxidative stress may increase biosynthesis of TAGs. Moderate drought stress resulted in a 60% reduction in TAG concentration in wheat (Triticum aestivum). Shading had no effect on TAGs, but increased concentrations of polar lipids in leaves; for example, acclimation to shade in Austrodanthonia spp., a native Australian grass, resulted in a 60% increase in associated polar lipids and higher foliar chlorophyll concentrations. Shading also reduced the digalactosyldiacylglycerol:monogalactosyldiacylglycerol (DGDG:MGDG) ratio in leaves, with a corresponding increase in the degree of unsaturation and thus fluidity of thylakoid membranes of chloroplasts. Our results suggest that prevention of photodamage may be coordinated with accumulation of TAGs, although further research is required to determine if TAGs serve a photoprotective function in plant leaves. © 2017 Scandinavian Plant Physiology Society.

  18. VT Telephone Exchange Boundaries

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The UtilityTelecom_EXCHANGE represents Vermont Telephone Exchange boundaries as defined by the VT Public Service Board. The original data was...

  19. Fluid to fluid contact heat exchanger

    Science.gov (United States)

    Clark, W. E.

    1986-01-01

    Heat transfer and pressure drop test results for a fluid to fluid contact heat exchanger are reported. The heat exchanger, fabricated and tested to demonstrate one method of transferring heat between structures in space, had a total contact area of 0.18 sq m. It utilized contact surfaces which were flexible and conformed to the mating contact surfaces upon pressurization of the fluid circulating within the heat exchanger. During proof-of-concept performance tests, the heat exchanger was operated in a typical earth environment. It demonstrated a contact conductance of 3.8 kW/sq m C at contact pressures in the 15 to 70 kPa range.

  20. Multi-Purpose Logistics Module (MPLM) Cargo Heat Exchanger

    Science.gov (United States)

    Zampiceni, John J.; Harper, Lon T.

    2002-01-01

    This paper describes the New Shuttle Orbiter's Multi- Purpose Logistics Modulo (MPLM) Cargo Heat Exchanger (HX) and associated MPLM cooling system. This paper presents Heat Exchanger (HX) design and performance characteristics of the system.

  1. Development of anion-exchange/reversed-phase high performance liquid chromatography-inductively coupled plasma-mass spectrometry methods for the speciation of bio-available iodine and bromine from edible seaweed.

    Science.gov (United States)

    Romarís-Hortas, Vanessa; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2012-05-04

    Anion exchange high performance liquid chromatography hyphenated with inductively coupled plasma-mass spectrometry has been novelly applied to assess inorganic (iodide and iodate) and organic (3-iodotyrosine - MIT, and 3,5-diiodotyrosine - DIT) iodine species in a single chromatographic run. The optimized operating conditions (Dionex IonPac AS7, gradient elution with 175 mM ammonium nitrate plus 15% (v/v) methanol, pH 3.8, as a mobile phase and flow rates within the 0.5-1.5 mL min(-1) range) have also been used to perform inorganic bromine speciation analysis (bromide and bromate). The developed method has been applied for determining the bio-available contents of iodine and bromine species in dialyzates from edible seaweed. Reverse phase high performance liquid chromatography (Zorbax Eclipse XDB-C8, gradient elution with 0.2% (m/m) acetic acid, and 0.2% (m/m) acetic acid in methanol, as mobile phases, and a constant flow rate of 0.75 mL min(-1)) also hyphenated with inductively coupled plasma-mass spectrometry was used to confirm the presence of organic iodine species (MIT and DIT) in the dialyzates. The verification of the presence of iodinated amino acids (MIT and DIT) in the extracts was also performed by reverse phase high performance liquid chromatography-electrospray ionization-mass spectrometry (LTQ Orbitrap). The developed methods have provided good repeatability (RSD values lower than 10% for both anion exchange and reverse phase separations) and analytical recoveries within the 90-105% range for all cases. The in vitro bio-availability method consisted of a simulated gastric and an intestinal digestion/dialysis (10 kDa molecular weight cut-off - MWCO) two-stage procedure. Iodide and MIT were the main bio-available species quantified, whereas bromide was the major bromine species found in the extracts. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Durability and performance of polystyrene- b -poly(vinylbenzyl trimethylammonium) diblock copolymer and equivalent blend anion exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Vandiver, Melissa A. [Department of Chemical and Biological Engineering, Colorado School of Mines, Golden Colorado 80401; Caire, Benjamin R. [Department of Chemical and Biological Engineering, Colorado School of Mines, Golden Colorado 80401; Poskin, Zach [Department of Chemical and Biological Engineering, Colorado School of Mines, Golden Colorado 80401; Li, Yifan [Department of Chemistry and Geochemistry, Colorado School of Mines, Golden Colorado 80401; Seifert, Sönke [X-Ray Science Division, Argonne National Laboratory, Argonne Illinois 60439; Knauss, Daniel M. [Department of Chemistry and Geochemistry, Colorado School of Mines, Golden Colorado 80401; Herring, Andrew M. [Department of Chemical and Biological Engineering, Colorado School of Mines, Golden Colorado 80401; Liberatore, Matthew W. [Department of Chemical and Biological Engineering, Colorado School of Mines, Golden Colorado 80401

    2014-11-01

    Anion exchange membranes (AEM) are solid polymer electrolytes that facilitate ion transport in fuel cells. In this study, a polystyrene-b-poly(vinylbenzyl trimethylammonium) diblock copolymer was evaluated as potential AEM and compared with the equivalent homopolymer blend. The diblock had a 92% conversion of reactive sites with an IEC of 1.72 ± 0.05 mmol g-1, while the blend had a 43% conversion for an IEC of 0.80 ± 0.03 mmol g-1. At 50°C and 95% relative humidity, the chloride conductivity of the diblock was higher, 24–33 mS cm-1, compared with the blend, 1–6 mS cm-1. The diblock displayed phase separation on the length scale of 100 nm, while the blend displayed microphase separation (~10 μm). Mechanical characterization of films from 40 to 90 microns thick found that elasticity and elongation decreased with the addition of cations to the films. At humidified conditions, water acted as a plasticizer to increase film elasticity and elongation. While the polystyrene-based diblock displayed sufficient ionic conductivity, the films' mechanical properties require improvement, i.e., greater elasticity and strength, before use in fuel cells. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41596.

  3. Development of a novel engineered E. coli host cell line platform with improved column capacity performance for ion-exchange chromatography.

    Science.gov (United States)

    Mukherjee, Rudra Palash; Fruchtl, McKinzie S; Beitle, Robert R; Brune, Ellen M

    2018-02-01

    This article reports on the analysis of an engineered Escherichia coli designed to reduce the host cell protein (HCP) burden on recombinant protein purification by column chromatography. Since downstream purification accounts for a major portion of production costs when using a recombinant platform, minimization of HCPs that are initially captured or otherwise interfere during chromatography will positively impact the entire purification process. Such a strategy, of course, would also require the cell line to grow, and express recombinant proteins, at levels comparable to, or better than, its parent strain. An E. coli strain with a small number of strategic deletions (LTSF06) was transformed to produce three different recombinant biologics to examine growth and expression, and with another model protein to assess growth and the effect of selectively reduced HCPs on target product capture on DEAE ion exchange medium. Cell growth levels were maintained or increased for all constructs, and a significant reduction in HCP adsorption was realized. Indeed, a breakthrough analysis indicated that as a result of reducing adsorption of particular HCPs, a 37% increase in target protein capture was observed. This increase in product capture efficiency was achieved by focusing not on HCPs that co-elute with the recombinant target, but rather on those possessing particular column adsorption and elution characteristics. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Production of high-performance and improved-durability Pt-catalyst /support for proton-exchange-membrane fuel cells with pulsed laser deposition

    Science.gov (United States)

    Huang, Ting-Wei; Qayyum, Hamza; Lin, Guan-Ren; Chen, Szu-yuan; Tseng, Chung-Jen

    2016-06-01

    Pulsed laser deposition in Ar atmosphere is used to deposit Pt nanoparticles onto gas diffusion layer, and its application to proton-exchange-membrane fuel cell is optimized and characterized. When used at anode side, with a Pt loading of 17 μg cm-2 the fuel-cell current density at 0.6 V reaches 1.08 A cm-2, which is close to that of a cell with the anode made by conventional slurry process using E-TEK Pt /C of 200 μg cm-2 Pt loading. The usage of Pt is decreased by 12 fold. Such a low usage of Pt prepared by pulsed laser deposition can be ascribed to the prevention of forming isolated regions that occurs with Pt /C slurry, good dispersion of Pt particles on support, and small particle sizes of 2-3 nm. Furthermore, using accelerated degradation test, it is found that the pulsed laser deposition sample retains 60% of its initial electrochemical surface area after 5000 potential cycles, much higher than that with E-TEK Pt /C, which retains only 7% of its initial electrochemical surface area. The higher electrochemical durability can be attributed to the higher degree of graphitization in the gas diffusion layer used as compared with the carbon black in E-TEK Pt /C, which leads to stronger binding of the Pt nanoparticles onto the carbon support and stronger corrosion resistance of the carbon support.

  5. Ideal Heat Exchange System

    Science.gov (United States)

    Tsirlin, A. M.

    2017-09-01

    The requirements with which a heat exchange system should comply in order that at certain values of the total contact surface and heat load the entropy production in it should be minimal have been determined. It has been shown that this system can serve as a standard for real systems of irreversible heat exchange. We have found the conditions for physical realizability of a heat exchange system in which heat exchange occurs by a law linear with respect to the temperature difference between contacting flows. Analogous conditions are given without deriving for the case of heat exchange by the Fourier law.

  6. New reversed phase-high performance liquid chromatographic method for selective separation of yttrium from all rare earth elements employing nitrilotriacetate complexes in anion exchange mode.

    Science.gov (United States)

    Dybczyński, Rajmund S; Kulisa, Krzysztof; Pyszynska, Marta; Bojanowska-Czajka, Anna

    2015-03-20

    Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Compact Ceramic Microchannel Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Lewinsohn, Charles [Ceramatec, Inc., Salt Lake City, UT (United States)

    2016-10-31

    The objective of the proposed work was to demonstrate the feasibility of a step change in power plant efficiency at a commercially viable cost, by obtaining performance data for prototype, compact, ceramic microchannel heat exchangers. By performing the tasks described in the initial proposal, all of the milestones were met. The work performed will advance the technology from Technology Readiness Level 3 (TRL 3) to Technology Readiness Level 4 (TRL 4) and validate the potential of using these heat exchangers for enabling high efficiency solid oxide fuel cell (SOFC) or high-temperature turbine-based power plants. The attached report will describe how this objective was met. In collaboration with The Colorado School of Mines (CSM), specifications were developed for a high temperature heat exchanger for three commercial microturbines. Microturbines were selected because they are a more mature commercial technology than SOFC, they are a low-volume and high-value target for market entry of high-temperature heat exchangers, and they are essentially scaled-down versions of turbines used in utility-scale power plants. Using these specifications, microchannel dimensions were selected to meet the performance requirements. Ceramic plates were fabricated with microchannels of these dimensions. The plates were tested at room temperature and elevated temperature. Plates were joined together to make modular, heat exchanger stacks that were tested at a variety of temperatures and flow rates. Although gas flow rates equivalent to those in microturbines could not be achieved in the laboratory environment, the results showed expected efficiencies, robust operation under significant temperature gradients at high temperature, and the ability to cycle the stacks. Details of the methods and results are presented in this final report.

  8. Photosynthesis, photoprotection and antioxidant activity of purging nut under drought deficit and recovery

    Energy Technology Data Exchange (ETDEWEB)

    Pompelli, Marcelo F.; Santos, Mauro G.; Almeida-Cortez, Jarcilene S. [Federal University of Pernambuco, Department of Botany, Plant Physiology Laboratory, Prof. Moraes Rego Av. s/n, Cidade Universitaria 50670901, Recife, PE (Brazil); Barata-Luis, Ricardo [Superior Institute of Agronomy, Technical University of Lisbon, Lisbon (Portugal); Vitorino, Hermerson S.; Goncalves, Eduardo R.; Rolim, Eduardo V.; Ferreira, Vilma M.; Lemos, Eurico E.; Endres, Lauricio [Plant Physiology Laboratory, Federal University of Alagoas, Maceio, Alagoas (Brazil)

    2010-08-15

    Biodiesel is an alternative to petroleum diesel fuel. It is a renewable, a biodegradable, and also a non-toxic fuel. The general interest to produce biodiesel from Jatropha (Jatropha curcas L.) seeds oil has increased but its ability to grow on drought-prone areas has barely been investigated. The objective of this work was to identify some physiological processes that allow the Jatropha to produce in severe arid conditions by studying its leaf gas exchange and antioxidant systems under drought stress and recovering. It measured the activity of antioxidant enzymes involved in the scavenge of reactive oxygen species (ROS), as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutamine synthetase (GS), as well as malondialdehyde (MDA) content. It was also analyzed the chlorophyll (CHL), carotenoids, amino acids and soluble proteins contents. Net photosynthesis (A) and stomata conductance (g{sub s}) decreased associate with drought stress and dropped to zero in soil water beneath 5%. Drought induced decrease in stomatal and non-stomatal photosynthetic activity. The activities of SOD, CAT, APX and GS and MDA content in leaves were significantly higher in the water-stressed plants compared to well-watered plants and decreased when the plants were rewatered. These observations suggest that oxidative stress resulting from drought deficit in Jatropha could result in the production of antioxidative enzymes to counteract the oxidative damage, and the enzymes may contribute to its ability to survive in the adverse arid environment. (author)

  9. Direct high-performance liquid chromatographic enantioseparation of free α-, β- And γ-aminophosphonic acids employing cinchona-based chiral zwitterionic ion exchangers Amino Acid Analysis

    NARCIS (Netherlands)

    Gargano, Andrea F.G.; Kohout, Michal; Macíková, Pavla; Lämmerhofer, Michael; Lindner, Wolfgang

    2013-01-01

    We report a chiral high-performance liquid chromatographic enantioseparation method for free α-aminophosphonic, β-aminophosphonic, and γ-aminophosphonic acids, aminohydroxyphosphonic acids, and aromatic aminophosphinic acids with different substitution patterns. Enantioseparation of these synthons

  10. Simultaneous determination of N-oxides and free bases of pyrrolizidine alkaloids by cation-exchange solid-phase extraction and ion-pair high-performance liquid chromatography.

    Science.gov (United States)

    Mroczek, Tomasz; Glowniak, Kazimierz; Wlaszczyk, Anna

    2002-03-08

    Cation-exchange solid-phase extraction using LiChrolut SCX (Merck, Darmstadt) cartridges filled with polymeric strong cation-exchanger enabled efficient isolation of both N-oxides and free bases of pyrrolizidine alkaloids (PAs). The recoveries were about 80% for retrorsine-N-oxide, 90% for retrorsine and 100% for senkirkine and were assessed both by TLC-densitometry and ion-pair high-performance liquid chromatography (HPIPC) on Hypersil BDS C8 stationary phase and hexane-l-sulfonic acid as ion-pairing agent. The applied HPIPC gradient procedure was suitable for separation of PAs with various types of structures (N-oxides, free bases, otonecine-PAs). The method limits of detection and quantitation, respectively, ranged from 0.06 ng/microl (senecionine) and 0.2 ng/microl (senkirkine) to 0.1 and 0.35 ng/microl for retrorsine-N-oxide. For each component calibrated by linear regression method, correlation coefficients were higher than 0.9995 (six-point calibration from 4 to 100 microg/ml). The elaborated procedure was used in searching for PAs in plant derived samples from Symphytum sp. (comfrey), Petasites hybridus and Petasites albus (butterbur), Tussilago farfara (coltsfoot), Emilia coccinea (tassel flower) and Doronicum columnae (leopard's bane). For the last three samples macrocyclic PAs (senecionine, senecionine-N-oxide. senkirkine) have been detected for the first time. Details of precision of the analyses are also included.

  11. Performance of polyethylene based radiation grafted anion exchange membrane with polystyrene-b-poly (ethylene/butylene)-b-polystyrene based ionomer using NiCo2O4 catalyst for water electrolysis

    Science.gov (United States)

    Gupta, Gaurav; Scott, Keith; Mamlouk, Mohamed

    2018-01-01

    A soluble anion exchange ionomer with high OH- ion conductivity comparable to that of H+ conductivity of Nafion is synthesised by chloromethylation of polystyrene-b-poly (ethylene/butylene)-b-polystyrene (SEBS) and used with NiCo2O4 electro-catalyst for water electrolysis. The ionomer has an ion exchange capacity of 1.9 mmol g-1 and ionic conductivity of 0.14 S cm-2 at 50 °C. The cell voltage at 20 °C at 100 mA cm-2 is 1.77 and 1.72 V in, 0.1 and 1.0 M NaOH, respectively, for an optimum loading of 10 mg cm-2 NiCo2O4. At 10 mg cm-2 NiCo2O4 electrolyser cell performance is at least equal to or superior to that of IrO2 at 2 mg cm-2 with excellent stability over 1 h. When the catalyst is sprayed on the GDL instead of CCM, the performance is further improved to 1.65 V at 100 mA cm-2 at 60 °C & 0.1 M KOH. The limited AEM electrolyser performance when operating with deionised water in comparison to PEM and alkaline electrolyser arises from the sluggish OER in the AEM environment equivalent to pH of 11.5 and the two orders of magnitude lower HER activity with respect to acid medium combined with the high Tafel slope of 120 mV dec-1.

  12. Essential Specification Elements for Heat Exchanger Replacement

    Energy Technology Data Exchange (ETDEWEB)

    Bower, L.

    2015-07-01

    Performance upgrade and equipment degradation are the primary impetuses for a nuclear power plant to engage in the large capital cost project of heat exchanger replacement. Along with attention to these issues, consideration of heat exchanger Codes and Standards, material improvements, thermal redesign, and configuration are essential for developing User’s Design Specifications for successful replacement projects. The User’s Design Specification is the central document in procuring ASME heat exchangers. Properly stated objectives for the heat exchanger replacement are essential for obtaining the materials, configurations and thermal designs best suited for the nuclear power plant. Additionally, the code of construction required and the applied manufacturing standard (TEMA or HEI) affects how the heat exchanger may be designed or configured to meet the replacement goals. Knowledge of how Codes and Standards affect design and configuration details will aid in writing the User’s Design Specification. Joseph Oat Corporation has designed and fabricated many replacement heat exchangers for the nuclear power industry. These heat exchangers have been constructed per ASME Section III to various Code-Years or ASME Section VIII-1 to the current Code-Year also in accordance with TEMA and HEI. These heat exchangers have been a range of like-for-like replacement to complete thermal, material and configuration redesigns. Several examples of these heat exchangers with their Code, Standard and specification implications are presented. (Author.

  13. Photoprotective Potential of Glycolic Acid by Reducing NLRC4 and AIM2 Inflammasome Complex Proteins in UVB Radiation-Induced Normal Human Epidermal Keratinocytes and Mice.

    Science.gov (United States)

    Hung, Sung-Jen; Tang, Sheau-Chung; Liao, Pei-Yun; Ge, Jheng-Siang; Hsiao, Yu-Ping; Yang, Jen-Hung

    2017-02-01

    Exposure to UVB radiation induces inflammation and free radical-mediated oxidative stress through reactive oxygen species (ROS) that play a crucial role in the induction of skin cancer. Glycolic acid (GA) is frequently used in cosmetics and dermatology. The aim of the study was to analyze the photoprotective mechanisms through which GA retards UVB-induced ROS accumulation and inflammation in normal human epidermal keratinocytes (NHEKs) and mice skin, respectively. NHEK cell line and C57BL/6J mice were treated with GA (0.1 or 5 mM) for 24 h followed by UVB irradiation. ROS accumulation, DNA damage, and expression of inflammasome complexes (NLRP3, NLRC4, ASC, and AIM2) were measured in vitro. Epidermal thickness and inflammasome complex proteins were analyzed in vivo. GA significantly prevented UVB-induced loss of skin cell viability, ROS formation, and DNA damage (single and double strands DNA break). GA suppressed the mRNA expression levels of NLRC4 and AIM2 among the inflammasome complexes. GA also blocked interleukin (IL)-1β by reducing the activity of caspase-1 in the NHEKs. Treatment with GA (2%) inhibited UVB-induced inflammation marker NLRC4 protein levels in mouse dorsal skin. The photoprotective activity of GA was ascribed to the inhibition of ROS formation and DNA damage, as well as a reduction in the activities of inflammasome complexes and IL-1β. We propose that GA has anti-inflammatory and photoprotective effects against UVB irradiation. GA is potentially beneficial to the protection of human skin from UV damage.

  14. Long-term ingestion of high flavanol cocoa provides photoprotection against UV-induced erythema and improves skin condition in women.

    Science.gov (United States)

    Heinrich, Ulrike; Neukam, Karin; Tronnier, Hagen; Sies, Helmut; Stahl, Wilhelm

    2006-06-01

    Dietary antioxidants contribute to endogenous photoprotection and are important for the maintenance of skin health. In the present study, 2 groups of women consumed either a high flavanol (326 mg/d) or low flavanol (27 mg/d) cocoa powder dissolved in 100 mL water for 12 wk. Epicatechin (61 mg/d) and catechin (20 mg/d) were the major flavanol monomers in the high flavanol drink, whereas the low flavanol drink contained 6.6 mg epicatechin and 1.6 mg catechin as the daily dose. Photoprotection and indicators of skin condition were assayed before and during the intervention. Following exposure of selected skin areas to 1.25 x minimal erythemal dose (MED) of radiation from a solar simulator, UV-induced erythema was significantly decreased in the high flavanol group, by 15 and 25%, after 6 and 12 wk of treatment, respectively, whereas no change occurred in the low flavanol group. The ingestion of high flavanol cocoa led to increases in blood flow of cutaneous and subcutaneous tissues, and to increases in skin density and skin hydration. Skin thickness was elevated from 1.11 +/- 0.11 mm at wk 0 to 1.24 +/- 0.13 mm at wk 12; transepidermal water loss was diminished from 8.7 +/- 3.7 to 6.3 +/- 2.2 g/(h x m2) within the same time frame. Neither of these variables was affected in the low flavanol cocoa group. Evaluation of the skin surface showed a significant decrease of skin roughness and scaling in the high flavanol cocoa group compared with those at wk 12. Dietary flavanols from cocoa contribute to endogenous photoprotection, improve dermal blood circulation, and affect cosmetically relevant skin surface and hydration variables.

  15. Securities and Exchange Commission Semiannual Regulatory Agenda

    Science.gov (United States)

    2010-12-20

    ... payments to the purchaser are dependent on the performance of a securities index. On July 12, 2010, a... Agency Contact: Martha Mahan Haines, Division of Trading and Markets, Securities and Exchange Commission...

  16. [Plasma exchange in nephrology: Indications and technique].

    Science.gov (United States)

    Ridel, Christophe; Kissling, Sébastien; Mesnard, Laurent; Hertig, Alexandre; Rondeau, Éric

    2017-02-01

    Plasma exchange is a non-selective apheresis technique that can be performed by filtration or centrifugation allowing rapid purification of high molecular weight pathogens. An immunosuppressive treatment is generally associated to reduce the rebound effect of the purified substance. Substitution solutes such as human albumin and macromolecules are needed to compensate for plasma extraction. Compensation by viro-attenuated plasma is reserved solely for the treatment of thrombotic microangiopathies or when there is a risk of bleeding, because this product is very allergenic and expensive. The treatment goal for a plasma exchange session should be between one and one and one-half times the patient's plasma volume estimated at 40 mL/kg body weight. The anticoagulation is best ensured by the citrate. Complications of plasma exchange are quite rare according to the French hemapheresis registry. The level of evidence of efficacy of plasma exchange in nephrology varies from one pathology to another. Main indications of plasma exchange in nephrology are Goodpasture syndrome, antineutrophil cytoplasmic antibody vasculitis when plasma creatinine is greater than 500 μmol/L, and thrombotic microangiopathies. During renal transplantation, plasma exchange may be proposed in the context of human leukocyte antigen (HLA) desensitization protocols or ABO-incompatible graft. After renal transplantation, plasma exchange is indicated as part of the treatment of acute humoral rejection or recurrent focal segmental glomerulosclerosis on the graft. Plasma exchanges are also proposed in the management of cryoglobulinemia or polyarteritis nodosa. Hemodialysis with membranes of very high permeability tends to replace plasma exchange for myeloma nephropathy. The benefit from plasma exchange has not been formally demonstrated for the treatment of severe lupus or antiphospholipid antibody syndrome. There is no indication of plasma exchange in the treatment of scleroderma or nephrogenic

  17. Photoprotection by Punica granatum seed oil nanoemulsion entrapping polyphenol-rich ethyl acetate fraction against UVB-induced DNA damage in human keratinocyte (HaCaT) cell line

    OpenAIRE

    Baccarin, T.; Mitjans Arnal, Montserrat; Ramos López, David; Lemos-Senna,Elenara; Vinardell Martínez-Hidalgo, Ma. Pilar

    2015-01-01

    There has been an increase in the use of botanicals as skin photoprotective agents. Pomegranate (Punica granatum L.) is well known for its high concentration of polyphenolic compounds and for its antioxidant and anti-inflammatory properties. The aim of this study was to analyse the photoprotection provided by Punica granatum seed oil nanoemulsion entrapping the polyphenol-rich ethyl acetate fraction against UVB-induced DNA damage in the keratinocyte HaCaT cell line. For this purpose, HaCaT ce...

  18. The photoprotective protein PsbS exerts control over CO(2) assimilation rate in fluctuating light in rice.

    Science.gov (United States)

    Hubbart, Stella; Ajigboye, Olubukola O; Horton, Peter; Murchie, Erik H

    2012-08-01

    A direct impact of chloroplastic protective energy dissipation (qE) on photosynthetic CO(2) assimilation has not been shown directly in plants in the absence of photoinhibition. To test this empirically we transformed rice to possess higher (overexpressors, OE) and lower (RNA interference, RNAi) levels of expression of the regulatory psbS gene and analysed CO(2) assimilation in transformants in a fluctuating measurement light regime. Western blots showed a several-fold difference in levels of PsbS protein between RNAi and OE plants with the wild type (WT) being intermediate. At a growth light intensity of 600 μmol m(-2) sec(-1) , the carboxylation capacity, electron transport capacity and dark adapted F(v)/F(m) (ratio of variable to maximum fluorescence) were inhibited in RNAi plants compared with WT and OE. The PsbS content had a significant impact on qE (measured here as non-photochemical quenching, NPQ) but the strongest effect was observed transiently, immediately following the application of light. This capacity for qE was several-fold lower in RNAi plants and significantly higher in OE plants during the first 10 min of illumination. At steady state the differences were reduced: notably at 500 μmol m(-2) sec(-1) all plants had the same NPQ values regardless of PsbS content. During a series of light-dark transitions the induction of CO(2) assimilation was inhibited in OE plants, reducing integrated photosynthesis during the light period. We conclude that the accumulation of PsbS and the resultant qE exerts control over photosynthesis in fluctuating light, showing that optimization of photoprotective processes is necessary for maximum photosynthetic productivity even in the absence of photoinhibitory stress. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

  19. Targeting NRF2 for Improved Skin Barrier Function and Photoprotection: Focus on the Achiote-Derived Apocarotenoid Bixin

    Science.gov (United States)

    Rojo de la Vega, Montserrat; Krajisnik, Andrea; Zhang, Donna D.; Wondrak, Georg T.

    2017-01-01

    The transcription factor NRF2 (nuclear factor-E2-related factor 2) orchestrates major cellular defense mechanisms including phase-II detoxification, inflammatory signaling, DNA repair, and antioxidant response. Recent studies strongly suggest a protective role of NRF2-mediated gene expression in the suppression of cutaneous photodamage induced by solar UV (ultraviolet) radiation. The apocarotenoid bixin, a Food and Drug Administration (FDA)-approved natural food colorant (referred to as ‘annatto’) originates from the seeds of the achiote tree native to tropical America, consumed by humans since ancient times. Use of achiote preparations for skin protection against environmental insult and for enhanced wound healing has long been documented. We have recently reported that (i) bixin is a potent canonical activator of the NRF2-dependent cytoprotective response in human skin keratinocytes; that (ii) systemic administration of bixin activates NRF2 with protective effects against solar UV-induced skin damage; and that (iii) bixin-induced suppression of photodamage is observable in Nrf2+/+ but not in Nrf2−/− SKH-1 mice confirming the NRF2-dependence of bixin-induced antioxidant and anti-inflammatory effects. In addition, bixin displays molecular activities as sacrificial antioxidant, excited state quencher, PPAR (peroxisome proliferator-activated receptor) α/γ agonist, and TLR (Toll-like receptor) 4/NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) antagonist, all of which might be relevant to the enhancement of skin barrier function and environmental stress protection. Potential skin photoprotection and photochemoprevention benefits provided by topical application or dietary consumption of this ethno-pharmacologically validated phytochemical originating from the Americas deserves further preclinical and clinical examination. PMID:29258247

  20. Targeting NRF2 for Improved Skin Barrier Function and Photoprotection: Focus on the Achiote-Derived Apocarotenoid Bixin.

    Science.gov (United States)

    Rojo de la Vega, Montserrat; Krajisnik, Andrea; Zhang, Donna D; Wondrak, Georg T

    2017-12-18

    The transcription factor NRF2 (nuclear factor-E2-related factor 2) orchestrates major cellular defense mechanisms including phase-II detoxification, inflammatory signaling, DNA repair, and antioxidant response. Recent studies strongly suggest a protective role of NRF2-mediated gene expression in the suppression of cutaneous photodamage induced by solar UV (ultraviolet) radiation. The apocarotenoid bixin, a Food and Drug Administration (FDA)-approved natural food colorant (referred to as 'annatto') originates from the seeds of the achiote tree native to tropical America, consumed by humans since ancient times. Use of achiote preparations for skin protection against environmental insult and for enhanced wound healing has long been documented. We have recently reported that (i) bixin is a potent canonical activator of the NRF2-dependent cytoprotective response in human skin keratinocytes; that (ii) systemic administration of bixin activates NRF2 with protective effects against solar UV-induced skin damage; and that (iii) bixin-induced suppression of photodamage is observable in Nrf2 +/+ but not in Nrf2 -/- SKH-1 mice confirming the NRF2-dependence of bixin-induced antioxidant and anti-inflammatory effects. In addition, bixin displays molecular activities as sacrificial antioxidant, excited state quencher, PPAR (peroxisome proliferator-activated receptor) α/γ agonist, and TLR (Toll-like receptor) 4/NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) antagonist, all of which might be relevant to the enhancement of skin barrier function and environmental stress protection. Potential skin photoprotection and photochemoprevention benefits provided by topical application or dietary consumption of this ethno-pharmacologically validated phytochemical originating from the Americas deserves further preclinical and clinical examination.