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Sample records for californium-252 plasma desorption

  1. Californium-252: a remarkable versatile radioisotope

    Energy Technology Data Exchange (ETDEWEB)

    Osborne-Lee, I.W.; Alexander, C.W.

    1995-10-10

    A product of the nuclear age, Californium-252 ({sup 252}Cf) has found many applications in medicine, scientific research, industry, and nuclear science education. Californium-252 is unique as a neutron source in that it provides a highly concentrated flux and extremely reliable neutron spectrum from a very small assembly. During the past 40 years, {sup 252}Cf has been applied with great success to cancer therapy, neutron radiography of objects ranging from flowers to entire aircraft, startup sources for nuclear reactors, fission activation for quality analysis of all commercial nuclear fuel, and many other beneficial uses, some of which are now ready for further growth. Californium-252 is produced in the High Flux Isotope Reactor (HFIR) and processed in the Radiochemical Engineering Development Center (REDC), both of which are located at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The REDC/HFIR facility is virtually the sole supplier of {sup 252}Cf in the western world and is the major supplier worldwide. Extensive exploitation of this product was made possible through the {sup 252}Cf Market Evaluation Program, sponsored by the United States Department of Energy (DOE) [then the Atomic Energy Commission (AEC) and later the Energy Research and Development Administration (ERDA)]. This program included training series, demonstration centers, seminars, and a liberal loan policy for fabricated sources. The Market Evaluation Program was instituted, in part, to determine if large-quantity production capability was required at the Savannah River Laboratory (SRL). Because of the nature of the product and the means by which it is produced, {sup 252}Cf can be produced only in government-owned facilities. It is evident at this time that the Oak Ridge research facility can meet present and projected near-term requirements. The production, shipment, and sales history of {sup 252}Cf from ORNL is summarized herein.

  2. Historical Review of Californium-252 Discovery and Development

    Science.gov (United States)

    Stoddard, D. H.

    1985-01-01

    This paper discusses the discovery and history of californium 252. This isotope may be synthesized by irradiating plutonium 239, plutonium 242, americium 243, or curium 244 with neutrons in a nuclear reactor. Various experiments and inventions involving Cf conducted at the Savannah River Plant are discussed. The evolution of radiotherapy using californium 252 is reviewed. (PLG)

  3. Production, Distribution, and Applications of Californium-252 Neutron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Balo, P.A.; Knauer, J.B.; Martin, R.C.

    1999-10-03

    The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-year half-life. A source the size of a person's little finger can emit up to 10{sup 11} neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6- year half-life. A source the size of a person's little finger can emit up to 10 neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory(ORNL). DOE sells {sup 252}Cf to commercial

  4. Teratogenic effect of Californium-252 irradiation in rats

    Energy Technology Data Exchange (ETDEWEB)

    Satow, Yukio; Lee, Juing-Yi; Hori, Hiroshi; Okuda, Hiroe; Tsuchimoto, Shigeo; Sawada, Shozo; Yokoro, Kenjiro (Hiroshima Univ. (Japan). Research Inst. for Nuclear Medicine and Biology)

    1989-06-01

    The teratogenicity of Californium-252 (Cf-252) irradiation which generates approximately 70% 2.3 MeV fast neutron and 30% gamma rays was evaluated. A single whole body exposure of Cf-252 at various doses was given to pregnant rats on day 8 or 9 of pregnancy, followed by microscopic autopsy of the fetuses at the terminal stage of pregnancy to search for external and internal malformations. For comparison, pregnant rats were irradiated with various doses of Cobalt-60 (Co-60) standard gamma rays at the same dose rate (1 rad/min.). The doses were 20-120 rad of Cf-252 and 80-220 rad of Co-60. Using frequency of radiation induced malformations observed on day 8 of pregnancy as an index, relative biological effectiveness (RBE) of 2.3-2.7 was obtained from the straight line obtained by modifying by the least squares method the frequency curves of malformed fetuses in total implants and in surviving fetuses. The types of malformations induced by Cf-252 and Co-60 irradiation were alike. Using fetal LD/sub 50/ as an index, 2.4 was obtained as RBE when irradiated on day 8 of pregnancy and 3.1 as that when irradiated on day 9. The results showed that Cf-252 had stronger a teratogenic effect than Co-60 gamma rays. (author).

  5. Apparatus for the measurement of total body nitrogen using prompt neutron activation analysis with californium-252.

    Science.gov (United States)

    Mackie, A; Hannan, W J; Smith, M A; Tothill, P

    1988-01-01

    Details of clinical apparatus designed for the measurement of total body nitrogen (as an indicator of body protein), suitable for the critically ill, intensive-care patient are presented. Californium-252 radio-isotopic neutron sources are used, enabling a nitrogen measurement by prompt neutron activation analysis to be made in 40 min with a precision of +/- 3.2% for a whole body dose equivalent of 0.145 mSv. The advantages of Californium-252 over alternative neutron sources are discussed. A comparison between two irradiation/detection geometries is made, leading to an explanation of the geometry adopted for the apparatus. The choice of construction and shielding materials to reduce the count rate at the detectors and consequently to reduce the pile-up contribution to the nitrogen background is discussed. Salient features of the gamma ray spectroscopy system to reduce spectral distortion from pulse pile-up are presented.

  6. Application of TSH bioindicator for studying the biological efficiency of neutrons from californium-252 source

    Energy Technology Data Exchange (ETDEWEB)

    Cebulska-Wasilewska, A.; Rekas, K. [Institute of Nuclear Physics, Cracow (Poland); Kim, J.K. [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)

    1997-12-31

    The effectiveness of neutrons from a Californium-252 source in the induction of various abnormalities in the Tradescantia clone 4430 stamen hair cells (TSH-assay) was studied. The special attention was paid to check whether any enhancement in effects caused by process of boron neutron capture is visible in the cells enriched with boron ions. Two chemicals (borax and BSH) were applied to introduce boron-10 ions into cells. Inflorescence, normal or pretreated with chemicals containing boron, were irradiated in the air with neutrons from a Cf-252 source at KAERI, Taejon, Korea. To estimate the relative biological effectiveness (RBE) in the induction of gene mutations of the neutron beam under the study, Tradescantia inflorescences, without any chemical pretreatment, were irradiated with various doses of X-rays. The ranges of radiation doses used were 0-0.1 Gy in neutrons and 0-0.5 Gy in X-rays. After the time needed to complete the postirradiation repair Tradescantia cuttings were transferred to Cracow, where screening of gene and lethal; mutations, cell cycle alterations in somatic cells have been done, and dose response relationships were figured. The maximal RBE values were estimated in the range of 4.6-6.8. Alterations of RBE value were observed; from 6.8 to 7.8 in the case of plants pretreated with 240 ppm of B-10 from borax, and 4.6 to 6.1 in the case of 400 ppm of B-10 from BSH. Results showed a slight, although statistically insignificant increase in biological efficacy of radiation from the Cf-252 source in samples pretreated with boron containing chemicals. (author)

  7. Clinical Report on Californium-252 Neutron Intraluminal Brachytherapy Combined with External Irradiation for Cervical Carcinoma Treatment

    Institute of Scientific and Technical Information of China (English)

    Huanyu Zhao; Keming Wang; Jian Sun; Xin Geng; Weiming Zhang

    2006-01-01

    OBJECTIVE To observe the curative effects and complications of californium-252 (252Cf) neutron intraluminal brachytherapy (IBT) combined with external irradiation (El) for treatment of cervical carcinoma.METHODS From December 2000 to December 2004, 128 cases of cervical carcinoma staged into ⅡA~ⅢB according to the International Federation of Gynecology and Obstetrics (FIGO) standards were treated with 252Cf neutron IBT using 8~10 Gy per fraction, once a week. The total dose at reference A point was 36~40 Gy in 4~5 fractions. From the second day after 252Cf neutron IBT treatment, the whole pelvic cavity was treated with 60Co γ-ray El, applying 2 Gy per fraction, 4 times per week. After 20~25 Gy of El, the center of the whole pelvic field was blocked with 4 cm of lead in width. The total dose of El was 45~50 Gy.RESULTS The short-term therapeutic effects were CR 95.3% and PR 4.7%. The 3 and 5-year local control rates were 93.5% and 87.9%. The overall 3-year survival rate was 87.5% and for Stages Ⅱ and Ⅲ , 90.9%and 81.5% respectively; the overall 5-year survival rate was 70% and for Stages Ⅱ and Ⅲ, 76.2% and 61% respectively. The rate of radiation complications was 4.7% for radiation cystitis, 7.8% for radiation proctitis, 6.3%for vagina contracture and adhesion and 5.5% for protracted radiation proctitis.CONCLUSION An combination of 252Cf neutron IBT with El for treatment of cervical carcinoma can be well-tolerated by cervical carcinoma patients. The rate of local tumor control is high and radiation complications are few.

  8. Application of TSH bioindicator for studying the biological efficiency of neutrons from californium-252 source

    Energy Technology Data Exchange (ETDEWEB)

    Cebulska-Wasilewska, A.; Rekas, K. [Institute of Nuclear Physics, Cracow (Poland); Kim, J.K. [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)

    1997-12-31

    The effectiveness of neutrons from a Californium-252 source in the induction of various abnormalities in the Tradescantia clone 4430 stamen hair cells (TSH-assay) was studied. The special attention was paid to check whether any enhancement in effects caused by process of boron neutron capture is visible in the cells enriched with boron ions. Two chemicals (borax and BSH) were applied to introduce boron-10 ions into cells. Inflorescence, normal or pretreated with chemicals containing boron, were irradiated in the air with neutrons from a Cf-252 source at KAERI, Taejon, Korea. To estimate the relative biological effectiveness (RBE) in the induction of gene mutations of the neutron beam under the study, Tradescantia inflorescences, without any chemical pretreatment, were irradiated with various doses of X-rays. The ranges of radiation doses used were 0-0.1 Gy in neutrons and 0-0.5 Gy in X-rays. After the time needed to complete the postirradiation repair Tradescantia cuttings were transferred to Cracow, where screening of gene and lethal; mutations, cell cycle alterations in somatic cells have been done, and dose response relationships were figured. The maximal RBE values were estimated in the range of 4.6-6.8. Alterations of RBE value were observed; from 6.8 to 7.8 in the case of plants pretreated with 240 ppm of B-10 from borax, and 4.6 to 6.1 in the case of 400 ppm of B-10 from BSH. Results showed a slight, although statistically insignificant increase in biological efficacy of radiation from the Cf-252 source in samples pretreated with boron containing chemicals. (author)

  9. Study of the shielding for spontaneous fission sources of Californium-252; Estudio de blindaje para fuentes de fision espontanea de Californio-252

    Energy Technology Data Exchange (ETDEWEB)

    Davila R, I

    1991-06-15

    A shielding study is made to attenuate, until maximum permissible levels, the neutrons radiation and photons emitted by spontaneous fission coming from a source of Californium-252. The compound package by a database (Library DLC-23) and the ANISNW code is used, in it version for personal computer. (Author)

  10. Californium-252 Brachytherapy Combined With External-Beam Radiotherapy for Cervical Cancer: Long-Term Treatment Results

    Energy Technology Data Exchange (ETDEWEB)

    Lei Xin; Qian Chengyuan; Qing Yi; Zhao Kewei; Yang Zhengzhou; Dai Nan; Zhong Zhaoyang; Tang Cheng; Li Zheng; Gu Xianqing; Zhou Qian; Feng Yan; Xiong Yanli; Shan Jinlu [Cancer Center, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing (China); Wang Dong, E-mail: dongwang64@hotmail.com [Cancer Center, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing (China)

    2011-12-01

    Purpose: To observe, by retrospective analysis, the curative effects and complications due to californium-252 ({sup 252}Cf) neutron intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT) in the treatment of cervical cancer. Methods and Materials: From February 1999 to December 2007, 696 patients with cervical cancer (Stages IB to IIIB) were treated with {sup 252}Cf-ICBT in combination of EBRT. Of all, 31 patients were at Stage IB, 104 at IIA, 363 at IIB, 64 at IIIA, and 134 at IIIB. Californium-252 ICBT was delivered at 7-12 Gy per insertion per week, with a total dose of 29-45 Gy to reference point A in three to five insertions. The whole pelvic cavity was treated with 8-MV X-ray external irradiation at 2 Gy per fraction, four times per week. After 16-38 Gy of external irradiation, the center of the whole pelvic field was blocked with a 4-cm-wide lead shield, with a total external irradiation dose of 44-56 Gy. The total treatment course was 5 to 6 weeks. Results: Overall survival rate at 3 and 5 years for all patients was 76.0% and 64.9%, respectively. Disease-free 3- and 5-year survival rates of patients were 71.2% and 58.4%, respectively. Late complications included vaginal contracture and adhesion, radiation proctitis, radiation cystitis, and inflammatory bowel, which accounted for 5.8%, 7.1%, 6.2%, and 4.9%, respectively. Univariate analysis results showed significant correlation of stage, age, histopathologic grade, and lymph node status with overall survival. Cox multiple regression analysis showed that the independent variables were stage, histopathologic grade, tumor size, and lymphatic metastasis in all patients. Conclusion: Results of this series suggest that the combined use of {sup 252}Cf-ICBT with EBRT is an effective method for treatment of cervical cancer.

  11. Long-term effects of an intracavitary treatment with californium-252 on normal tissue. [Swine, /sup 226/Ra

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, M.F.; Beamer, J.L.; Mahony, T.D.; Cross, F.T.; Lund, J.E.; Endres, G.W.R.

    1976-01-01

    About one hundred fifty swine were exposed to either radium-226 or californium-252 sources in the uterine cervix to determine an RBE for both acute and long-term effects. That value for early changes in the tissues at risk in the treatment of cervical cancer was between 6.2 and 6.8. The incidence of complications increased with time after exposure, especially among animals treated with /sup 252/Cf. Analysis of rectal injury showed that ulceration occurred frequently within a year postexposure at doses between 1600 and 2400 rad calculated at 2 cm lateral to the source midline. Fat necrosis and smooth muscle atrophy, resulting in a local rectal stricture, were delayed changes observed in some animals. The lower ureter was the site for a greater frequency of complications than the GI tract. Ureteral stricture often occurred at doses of 1200 rad from /sup 252/Cf and 7000 rad from /sup 226/Ra. Observation of delayed effects in the uterine-cervix in animals held up to 4 years postexposure indicate that the RBE for /sup 252/Cf may be increased to a value as high as 18, while repair may have even decreased it to about 5.6 in the rectum. Fifty swine are still being observed for long-term effects after doses above 800 rad from /sup 252/Cf and 5000 rad from /sup 226/Ra.

  12. Low-Dose-Rate Californium-252 Neutron Intracavitary Afterloading Radiotherapy Combined With Conformal Radiotherapy for Treatment of Cervical Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Min [Department of Oncology, Armed Police Hospital of Hangzhou, Hangzhou, Zhejiang Province (China); Xu Hongde [Cancer Center, Armed Police Hospital of Hangzhou, Hangzhou, Zhejiang Province (China); Pan Songdan; Lin Shan; Yue Jianhua [Department of Oncology, Armed Police Hospital of Hangzhou, Hangzhou, Zhejiang Province (China); Liu Jianren, E-mail: liujianren0571@hotmail.com [Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province (China)

    2012-07-01

    Purpose: To study the efficacy of low-dose-rate californium-252 ({sup 252}Cf) neutron intracavitary afterloading radiotherapy (RT) combined with external pelvic RT for treatment of cervical cancer. Methods and Materials: The records of 96 patients treated for cervical cancer from 2006 to 2010 were retrospectively reviewed. For patients with tumors {<=}4 cm in diameter, external beam radiation was performed (1.8 Gy/day, five times/week) until the dose reached 20 Gy, and then {sup 252}Cf neutron intracavitary afterloading RT (once/week) was begun, and the frequency of external beam radiation was changed to four times/week. For patients with tumors >4 cm, {sup 252}Cf RT was performed one to two times before whole-pelvis external beam radiation. The tumor-eliminating dose was determined by using the depth limit of 5 mm below the mucosa as the reference point. In all patients, the total dose of the external beam radiation ranged from 46.8 to 50 Gy. For {sup 252}Cf RT, the dose delivered to point A was 6 Gy/fraction, once per week, for a total of seven times, and the total dose was 42 Gy. Results: The mean {+-} SD patient age was 54.7 {+-} 13.7 years. Six patients had disease assessed at stage IB, 13 patients had stage IIA, 49 patients had stage IIB, 3 patients had stage IIIA, 24 patients had stage IIIB, and 1 patient had stage IVA. All patients obtained complete tumor regression (CR). The mean {+-} SD time to CR was 23.5 {+-} 3.4 days. Vaginal bleeding was fully controlled in 80 patients within 1 to 8 days. The mean {+-} SD follow-up period was 27.6 {+-} 12.7 months (range, 6-48 months). Five patients died due to recurrence or metastasis. The 3-year survival and disease-free recurrence rates were 89.6% and 87.5 %, respectively. Nine patients experienced mild radiation proctitis, and 4 patients developed radiocystitis. Conclusions: Low-dose-rate {sup 252}Cf neutron RT combined with external pelvic RT is effective for treating cervical cancer, with a low incidence of

  13. Design of a homogeneous subcritical nuclear reactor based on thorium with a source of californium 252; Diseno de un reactor nuclear subcritico homogeneo a base de Torio con una fuente de Californio 252

    Energy Technology Data Exchange (ETDEWEB)

    Delgado H, C. E.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico); Sajo B, L., E-mail: ce_delgado89@hotmail.com [Universidad Simon Bolivar, Laboratorio de Fisica Nuclear, Apdo. 89000, 1080A Caracas (Venezuela, Bolivarian Republic of)

    2015-10-15

    Full text: One of the energy alternatives to fossil fuels which do not produce greenhouse gases is the nuclear energy. One of the drawbacks of this alternative is the generation of radioactive wastes of long half-life and its relation to the generation of nuclear materials to produce weapons of mass destruction. An option to these drawbacks of nuclear energy is to use Thorium as part of the nuclear fuel which it becomes in U{sup 233} when capturing neutrons, that is a fissile material. In this paper Monte Carlo methods were used to design a homogeneous subcritical reactor based on thorium. As neutron reflector graphite was used. The reactor core is homogeneous and is formed of 70% light water as moderator, 12% of enriched uranium UO{sub 2}(NO{sub 3}){sub 4} and 18% of thorium Th(NO{sub 3}){sub 4} as fuel. To start the nuclear fission chain reaction an isotopic source of californium 252 was used with an intensity of 4.6 x 10{sup 7} s{sup -1}. In the design the value of the effective multiplication factor, whose value turned out k{sub eff} <1 was calculated. Also, the neutron spectra at different distances from the source and the total fluence were calculated, as well as the values of the ambient dose equivalent in the periphery of the reactor. (Author)

  14. Manganese determination om minerals by activation analysis, using the californium-252 as a neutron source; Determinacao de manganes em minerios, por analise por ativacao, usando californio-252 como fonte de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Antonio

    1976-07-01

    Neutron Activation Analysis, using a Californium-252 neutron source, has been applied for the determination of manganese in ores such as pyrolusite, rodonite (manganese silicate)' and blending used in dry-batteries The favorable nuclear properties of manganese, such as high thermal neutron cross-section for the reaction {sup 55}Mn (n.gamma){sup 56} Mn, high concentration of manganese in the matrix and short half - life of {sup 56}Mn, are an ideal combination for non-destructive analysis of manganese in ores. Samples and standards of manganese dioxide were irradiated for about 20 minutes, followed by a 4 to 15 minutes decay and counted in a single channel pulse-height discrimination using a NaI(Tl) scintillation detector. Counting time was equal to 10 minutes. The interference of nuclear reactions {sup 56}Fe(n,p){sup 56}Mn and {sup 59} Co (n, {alpha}){sup 56} were studied, as well as problems in connection with neutron shadowing during irradiation, gamma-rays attenuation during counting and influence of granulometry of samples. One sample,was also analysed by wet-chemical method (sodium bismuthate) in order to compare results. As a whole, i t was shown that the analytical method of neutron activation for manganese in ores and blending, is a method simple, rapid and with good precision and accuracy. (author)

  15. SVSCf plasma desorption mass spectrometry: recent advances and applications

    Energy Technology Data Exchange (ETDEWEB)

    Kamensky, I.; Craig, A.G.

    1987-01-01

    SVSCf plasma desorption mass spectrometry (PDMS) as utilized in the BIO-ION instruments is described. The sensitivity of the technique is investigated for varying amounts of bovine insulin. The results show accurate mass assignment for pmole amounts of sample. Several methods, currently used for sample preparation in PDMS, are described. Spectra of the antibiotic nisin using two different sample preparation techniques show significant variation. The fragmentation pattern of reduced acetylated maltoheptaose is also presented. The initial results obtained using a new PDMS instrument equipped with variable flight path are shown. The increased resolution is illustrated using the extended flight path to measure the molecular ion region of the maltoheptaose.

  16. Plasma Desorption Mass Spectrometry analysis of HCOOH ice

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, D.P.P.; Rocco, M.L.M. [Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, Ilha do Fundao, 21949-900 Rio de Janeiro, RJ (Brazil); Boechat-Roberty, H.M. [Observatorio do Valongo, Universidade Federal do Rio de Janeiro, Ladeira Pedro Antonio, 43, Centro, Rio de Janeiro, RJ (Brazil); Iza, P.; Martinez, R. [Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, 22543-900 Rio de Janeiro (Brazil); Homem, M.G.P. [Laboratorio Nacional de Luz Sincrotron (LNLS), Box 6192, 13084-971 Campinas, SP (Brazil); Silveira, E.F. da [Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, 22543-900 Rio de Janeiro (Brazil)], E-mail: enio@vdg.fis.puc-rio.br

    2007-03-15

    Planetary magnetospheres, in which outer planet satellites orbit, are bombarded by energetic particles inducing chemical and physical changes in their icy surfaces. The existing condensed gases react to form new products, which then undergo thermal evolution from the natural day/night cycles of these satellites. Plasma irradiation of ice causes phase changes, e.g., water ice from crystalline to amorphous over short timescales. When ice is recrystallized by heating, the surface layers retain some disorder, which promote reactions among adsorbed molecules such as H{sub 2}O, CO{sub 2}, CH{sub 2}CO, HCOOH and theirs radiolysis products. In this work, chemical reactions involving formic acid condensed at 56 K are analyzed by using Plasma Desorption Mass Spectrometry-time-of-flight ({sup 252}Cf-PDMS-TOF). Mass spectra of positive and negative desorbed ions were obtained, giving information on the structure and abundance of the molecules on the ice; the expected cations and anions generated by the HCOOH dissociation have been observed. Furthermore, several series of cluster ions were also detected, all exhibiting the structure X{sub n}Y{sub m}R{sup {+-}}, where X and Y are the neutral ice molecules, such as HCOOH or H{sub 2}O, and R{sup {+-}} is either an atomic or a molecular ion, such as H{sup +}, H{sub 3}O{sup +} or COOH{sup -}. In general, the desorption yields of the observed positive and negative ions are characterized by a decreasing exponential function as the emitted ion mass increases; however, the (HCOOH){sub n}OH{sup -} series presents its maximum at n = 8.

  17. Desorption of isopropyl alcohol from adsorbent with non-thermal plasma.

    Science.gov (United States)

    Shiau, Chen Han; Pan, Kuan Lun; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

    2016-11-24

    Effective desorption of isopropyl alcohol (IPA) from adsorbents with non-thermal plasma is developed. In this system, IPA is effectively adsorbed with activated carbon while dielectric barrier discharge is applied to replace the conventional thermal desorption process to achieve good desorption efficiency, making the treatment equipment smaller in size. Various adsorbents including molecular sieves and activated carbon are evaluated for IPA adsorption capacity. The results indicate that BAC has the highest IPA adsorption capacity (280.31 mg IPA/g) under the operating conditions of room temperature, IPA of 400 ppm, and residence time of 0.283 s among 5 adsorbents tested. For the plasma desorption process, the IPA selectivity of 89% is achieved with BAC as N2 is used as desorbing gas. In addition, as air or O2 is used as desorbing gas, the IPA desorption concentration is reduced, because air and O2 plasmas generate active species to oxidize IPA to form acetone, CO2, and even CO. Furthermore, the results of the durability test indicate that the amount of IPA desorbed increases with increasing desorption times and plasma desorption process has a higher energy efficiency if compared with thermal desorption. Overall, this study indicates that non-thermal plasma is a viable process for removing VOCs to regenerate adsorbent.

  18. Desorption behavior of zinc atoms from zinc-sulfate solution irradiated with pulsed DC plasma

    Science.gov (United States)

    Takaba, Takafumi; Suzuki, Haruka; Toyoda, Hirotaka

    2016-07-01

    A DC pulsed plasma ignited between a metal needle and zinc sulfate (ZnSO4) solution electrode was used to investigate Zn metal desorption from an electrolyte solution. Using an ICCD camera and optical band-pass filter, 2D atomic absorption spectroscopy was carried out during irradiation of pulsed plasma to the surface of the solution. The time-resolved measurement of Zn atoms released to the gas phase revealed that the Zn desorption rate monotonically increased with increasing number of discharge repetitions. The surface temperature of the electrolyte solution was observed with a thermographic camera, and correlations between the H2O and Zn desorption rate were inspected. The correlation between the H2O and Zn desorption rate suggested that Zn desorption is assisted not only by the electric field of the discharge but also by H2O evaporating from the solution.

  19. {sup 252}Cf plasma desorption and laser desorption mass spectrometry for the determination of molecular weight distribution of coal derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, B.R.; Bartle, K.D.; Ross, A.B.; Herod, A.A.; Kandiyoti, R.; Larsen, J.W. [University of Leeds, Leeds (United Kingdom). School of Chemistry

    1999-11-01

    A detailed knowledge of the molecular mass (MM) distribution in coal and its derived products is essential for a fundamental understanding of coal structure, and of the processes occurring during coal conversion. Fractionation using size exclusion chromatography (s.e.c.) using N-methyl-2-pyrrolidinone as the mobile phase has been applied to such materials and has provided improved MM distributions. Absolute calibration has been provided using matrix assisted laser desorption ionisation mass spectrometry (MAl.d.I.-m.s.). An alternative method of volatilising and ionising large molecules for mass spectrometry (m.s.) is {sup 252}Cf plasma desorption ({sup 252}Cf p.d.-m.s.). This involves the use of energetic fission fragments from the decay of {sup 252}Cf and produces mass spectra consisting predominantly of molecular ions from a range of polymers and biomolecules. This has been used by other workers to determine the molecular weight distribution of heavy distillation residues obtained from coal liquefaction processes either unfractionated or fractionated into broad fractions. Generally, a good agreement was obtained between values of MM determined by {sup 252}Cf p.d.-m.s. and s.e.c. A comparison is reported of MM distribution determined by {sup 252}Cf p.d.-m.s. and laser desorption mass spectrometry (l.d.-m.s.) for narrower fractions separated by s.e.c. from a coal tar pitch. 19 refs., 4 figs., 1 tab.

  20. Hydrogen desorption from hydrogen fluoride and remote hydrogen plasma cleaned silicon carbide (0001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    King, Sean W., E-mail: sean.king@intel.com; Tanaka, Satoru; Davis, Robert F. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Nemanich, Robert J. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2015-09-15

    Due to the extreme chemical inertness of silicon carbide (SiC), in-situ thermal desorption is commonly utilized as a means to remove surface contamination prior to initiating critical semiconductor processing steps such as epitaxy, gate dielectric formation, and contact metallization. In-situ thermal desorption and silicon sublimation has also recently become a popular method for epitaxial growth of mono and few layer graphene. Accordingly, numerous thermal desorption experiments of various processed silicon carbide surfaces have been performed, but have ignored the presence of hydrogen, which is ubiquitous throughout semiconductor processing. In this regard, the authors have performed a combined temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) investigation of the desorption of molecular hydrogen (H{sub 2}) and various other oxygen, carbon, and fluorine related species from ex-situ aqueous hydrogen fluoride (HF) and in-situ remote hydrogen plasma cleaned 6H-SiC (0001) surfaces. Using XPS, the authors observed that temperatures on the order of 700–1000 °C are needed to fully desorb C-H, C-O and Si-O species from these surfaces. However, using TPD, the authors observed H{sub 2} desorption at both lower temperatures (200–550 °C) as well as higher temperatures (>700 °C). The low temperature H{sub 2} desorption was deconvoluted into multiple desorption states that, based on similarities to H{sub 2} desorption from Si (111), were attributed to silicon mono, di, and trihydride surface species as well as hydrogen trapped by subsurface defects, steps, or dopants. The higher temperature H{sub 2} desorption was similarly attributed to H{sub 2} evolved from surface O-H groups at ∼750 °C as well as the liberation of H{sub 2} during Si-O desorption at temperatures >800 °C. These results indicate that while ex-situ aqueous HF processed 6H-SiC (0001) surfaces annealed at <700 °C remain terminated by some surface C–O and

  1. Automated absolute activation analysis with californium-252 sources

    Energy Technology Data Exchange (ETDEWEB)

    MacMurdo, K.W.; Bowman, W.W.

    1978-09-01

    A 100-mg /sup 252/Cf neutron activation analysis facility is used routinely at the Savannah River Laboratory for multielement analysis of many solid and liquid samples. An absolute analysis technique converts counting data directly to elemental concentration without the use of classical comparative standards and flux monitors. With the totally automated pneumatic sample transfer system, cyclic irradiation-decay-count regimes can be pre-selected for up to 40 samples, and samples can be analyzed with the facility unattended. An automatic data control system starts and stops a high-resolution gamma-ray spectrometer and/or a delayed-neutron detector; the system also stores data and controls output modes. Gamma ray data are reduced by three main programs in the IBM 360/195 computer: the 4096-channel spectrum and pertinent experimental timing, counting, and sample data are stored on magnetic tape; the spectrum is then reduced to a list of significant photopeak energies, integrated areas, and their associated statistical errors; and the third program assigns gamma ray photopeaks to the appropriate neutron activation product(s) by comparing photopeak energies to tabulated gamma ray energies. Photopeak areas are then converted to elemental concentration by using experimental timing and sample data, calculated elemental neutron capture rates, absolute detector efficiencies, and absolute spectroscopic decay data. Calculational procedures have been developed so that fissile material can be analyzed by cyclic neutron activation and delayed-neutron counting procedures. These calculations are based on a 6 half-life group model of delayed neutron emission; calculations include corrections for delayed neutron interference from /sup 17/O. Detection sensitivities of < or = 400 ppB for natural uranium and 8 ppB (< or = 0.5 (nCi/g)) for /sup 239/Pu were demonstrated with 15-g samples at a throughput of up to 140 per day. Over 40 elements can be detected at the sub-ppM level.

  2. Paired observation of californium-252 neutron intraluminal brachytherapy combined with external-beam radiotherapy with and without lead shielding for cervical cancer%252 Cf中子腔内照射结合挡铅与不挡铅外照射治疗宫颈癌的配对观察

    Institute of Scientific and Technical Information of China (English)

    戴卓捷; 雷新; 陈永红; 刘佳

    2015-01-01

    目的:比较252 Cf中子腔内照射结合挡铅盆腔对穿野和不挡铅箱式四野外照射治疗宫颈癌的治疗结果。方法2004—2007年本院收治的Ⅱa—Ⅲb 期的宫颈鳞癌患者,按照临床分期、年龄、肿瘤大小、贫血程度为配对条件,共筛选出26对(52例)研究对象,分为挡铅盆腔对穿野组(挡铅组)和不挡铅箱式四野组(不挡铅组)。两组患者外照射期间穿插252 Cf中子后装治疗。 Kaplan?Meier法计算5年LC、OS、DFS 并 Logrank 检验差异,晚期并发症发生率差异行 McNemar 法检验。结果挡铅、不挡铅组5年LC 率分别为85%、81%(P=0??014),OS 率分别为89%、73%(P=0??013),DFS 率分别为89%、73%(P=0??013),晚期并发症发生率分别为12%、23%(P=0??008)。结论腔内照射结合外照射治疗宫颈癌时无论采取对穿野还是箱式四野,后程前后野中央均应挡铅。%Objective To compare the efficacy between californium?252 ( 252 Cf ) neutron intraluminal brachytherapy combined with external?beam radiotherapy with lead?shielding pelvic parallel opposing field technique and non?lead?shielding four?field box technique for cervical cancer. Methods A total of 52 patients with stage Ⅱa?Ⅲb cervical squamous cell carcinoma who were admitted to our hospital from 2004 to 2007 were enrolled as subjects and paired by clinical stage, age, tumor size, and degree of anemia. The 26 pairs of patients were divided into lead?shielding pelvic parallel opposing field group (lead?shielding group) and non?lead?shielding four?field box group (non?lead?shielding group). For all patients in both groups, 252 Cf neutron brachytherapy was added in external?beam radiotherapy. The local control (LC), overall survival (OS), and disease?free survival (DFS) rates were calculated using the Kaplan?Meier method and analyzed using the log?rank test. The difference in the incidence of late complications was

  3. Probing silicon substitution in molecular sieves by plasma desorption mass spectrometry

    Science.gov (United States)

    Van Stipdonk, M. J.; von Heimburg, S. L.; Schweikert, E. A.

    1998-10-01

    Plasma desorption was used to produce secondary ion mass spectra from samples of unsubstituted and substituted aluminum phosphate materials. The yield of fingerprint ions representative of silicon oxide solids indicates that the incorporation of silicon into the material during synthesis and following calcination occurs via the formation of silicon-rich islands. Complementary X-ray photoelectron data provide supporting evidence that the surface of the substituted aluminum phosphate material becomes silicon rich and phosphorus depleted. No changes in the unsubstituted and substituted material with respect to composition and phase were detected using powder X-ray diffraction.

  4. The effects of added hydrogen on a helium atmospheric-pressure plasma jet ambient desorption/ionization source.

    Science.gov (United States)

    Wright, Jonathan P; Heywood, Matthew S; Thurston, Glen K; Farnsworth, Paul B

    2013-03-01

    We present mass spectrometric data demonstrating the effect that hydrogen has on a helium-based dielectric-barrier discharge (DBD) atmospheric-pressure plasma jet used as an ambient desorption/ionization (ADI) source. The addition of 0.9 % hydrogen to the helium support gas in a 35-W plasma jet increased signals for a range of test analytes, with enhancement factors of up to 68, without proportional increases in background levels. The changes in signal levels result from a combination of changes in the desorption kinetics from the surface and increased ion production in the gas phase. The enhancement in ADI-MS performance despite the quenching of key plasma species reported in earlier studies suggests that ionization with a H2/He plasma jet is the result of an alternate mechanism involving the direct generation of ionized hydrogen.

  5. A SIMPLE AND RAPID MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME OF FLIGHT MASS SPECTROMETRY METHOD TO SCREEN FISH PLASMA SAMPLES FOR ESTROGEN-RESPONSIVE BIOMARKERS

    Science.gov (United States)

    In this study, we describe and evaluate the performance of a simple and rapid mass spectral method for screening fish plasma for estrogen-responsive biomarkers using matrix assisted laster desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) couopled with a short...

  6. Determination of metformin in mouse, rat, dog and human plasma samples by laser diode thermal desorption/atmospheric pressure chemical ionization tandem mass spectrometry.

    Science.gov (United States)

    Swales, John G; Gallagher, Richard; Peter, Raimund M

    2010-11-02

    A simple, rapid and robust high-throughput assay for the quantitative analysis of metformin in plasma from different species using laser diode thermal desorption interfaced with atmospheric chemical pressure ionization tandem mass spectrometry (LDTD-APCI-MSMS) was developed for use in a pharmaceutical discovery environment. In order to minimize sample preparation a generic protein precipitation method was used to extract metformin from the plasma. Laser diode thermal desorption is a relatively new sample introduction method, the optimization of the instrumental parameters are presented. The method was successfully applied to spiked mouse, rat, dog and human plasma samples and was subsequently used to determine the oral pharmacokinetics of metformin after dosing to male rats in order to support drug discovery projects. The deviations for intra-assay accuracy and precision across the four species were less than 30% at all calibration and quality control levels.

  7. Deuterium recycling rate constants derived from plasma implantation/desorption shots in a martensitic steel surface

    Energy Technology Data Exchange (ETDEWEB)

    Sedano, L.A. [CIEMAT/DIAE, Madrid (Spain); European Commission/JRC, H-Materials Interaction Sector, Ispra (Italy); Esteban, G.A. [UPV-EHU/ETSIIT, D. Nuc. Eng. and Fluid Mec., Bilbao (Spain); Perujo, A. [European Commission/JRC, H-Materials Interaction Sector, Ispra (Italy)

    2001-12-04

    The recombination (K{sub 2}) and dissociation rate constants (K{sub 1}) are essential magnitudes for the tracking of tritium at the first wall (FW) of fusion reactors (FR). This paper presents our plasma implantation/recycling test, the modelling of the experiment and the results obtained for K{sub 2} and K{sub 1} in the case of a deuterium (D{sub 3}{sup +}/D{sub 2}{sup +}) plasma in the martensitic steel DIN 1.4914 (MANET). Once parasitic contributions were accounted, the D{sub 2} release from the target was seen to be surface limited. The values obtained for K{sub 1} and K{sub 2} show low dispersion on impinging flux and ion energies. For K{sub 1} a roughly constant value of 7 x 10{sup -6} mol Pa{sup -1} m{sup -2} s{sup -1} is derived. The obtained K{sub 2} is written as: K{sub 2} = 2.414 exp (-1571/RT) (m{sup 4} mol{sup -1} s{sup -1}), with R = 8.314 J mol{sup -1} K{sup -1}. Our activation energies agree with those existing in the literature derived from permeation experiments. High reflection coefficients are derived, which are in good agreement with the classical theory of ion scattering at low energy. (orig.)

  8. Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for californium-252 medical sources

    Science.gov (United States)

    Rivard, Mark Joseph

    Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a variety of clinically relevant materials. Herein, a Maxwellian spectrum was used to model the 252Cf neutron emissions within these materials. 252Cf mixed-field dosimetry of Applicator Tube (AT) type sources was measured using 1.0 and 0.05 cm3 tissue-equivalent ion chambers and a miniature GM counter. A dosimetry protocol was formulated similar that of ICRU 45. The 252Cf AT neutron dosimetry was determined in the cylindrical coordinate system formalism recommended by the AAPM Task Group 43. These results demonstrated the overwhelming dependence of dosimetry on the source geometry factor as there was no significant neutron attenuation within the source or encapsulation. Gold foils and TLDs were used to measure the thermal flux in the vicinity of 252Cf AT sources to compare with the results calculated using MCNP. As the fast neutron energy spectrum did not markedly changed at increasing distances from the AT source, neutron dosimetry results obtained with paired ion chambers using fixed sensitivity factors agreed well with MCNP results and those in the literature. Calculations of moderated 252Cf neutron energy spectrum with various loadings of 10B and 157Gd were performed, in addition to analysis of neutron capture therapy dosimetry with these isotopes. Radiological concerns such as personnel exposure and shielding of 252Cf emissions were examined. Feasibility of a high specific-activity 252Cf HDR source was investigated through radiochemical and metallurgical studies using stand-ins such as Tb, Gd and 249Cf. Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. A recommended 252Cf source strength of at least 1mg was necessary for fabrication of a 252Cf HDR source.

  9. Design and Potentials of the Californium-252 Radiation Facility at WES

    Science.gov (United States)

    1975-09-01

    standards, using an Image Quality Indicator (IQI) and also a Beam Purity Indicator (BPI),** shows a relatively good thermal and epithermal neutron ...colli-nated beam of the desired neutron radiation. Consideration of the basic nuclear properties was therefore a necessity in achieving the desired...The upper 6 ft has been designed for use in radiography and neutron counting. The steel tank was prefabricated in two sections. The lower 6-ft

  10. Large molecular mass materials in coal-derived liquids by {sup 252}Cf-plasma and matrix-assisted laser desorption mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Domin, M.; Li, S.; Lazaro, M.-J.; Herod, A.A.; Larsen, J.W.; Kandiyoti, R. [School of Pharmacy, London (United Kingdom). Dept. of Parmaceutical and Biological Chemistry

    1998-05-01

    The paper compares responses of {sup 252}Cf-plasma desorption MS (PD-MS) and matrix-assisted laser desorption (MALDI) MS to identical samples. The two pairs of samples selected for the comparison were known from previous work to differ significantly in their high mass contents. MALDI-MS showed large differences in MM distributions within both pairs of samples. The PD-MS data showed a degree of similarity between one pair of samples (pyridine soluble/insoluble fractions of a coal tar pitch); for the second pair (a coal extract and its hydrocracked product), trends from the two MS techniques agreed closely. The MM range observed by PD-MS was somewhat narrower, extending to between 3000 and 5000 u. Significant differences within pairs of samples were observed by SEC and by UV-fluorescence spectroscopy, providing somewhat closer agreement with the MALDI spectra. The two MS instruments differ in two important respects: the ionization system (i.e., plasma vs laser desorption) and the maximum available ion extraction voltage: 30 kV for the MALDI-MS instrument and 15 kV for the PD-MS. The comparison of plasma vs laser desorption mass spectroscopy could not therefore take place at high ion extraction voltages. Work at up to 30 kV in the MALDI instrument indicated better sensitivity to high-mass materials at higher ion extraction voltages. The qualitative similarity of results from the two MS techniques is nevertheless apparent; the range of MMs observed in PD-MS as well as in MALDI-MS were, furthermore, far larger than those reported by any MS technique, to date. 38 refs., 6 figs., 1 tab.

  11. Large molecular mass materials in coal derived liquids by {sup 252}Cf-plasma and matrix assisted laser desorption mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Domin, M. [School of Pharmacy, London (United Kingdom). Dept. of Pharmaceutical and Biological Chemistry; Li, S.; Herod, A.A.; Larsen, J.W. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Chemistry; Lazaro, M.J.; Kandiyoti, R. [Imperial College, London (United Kingdom). Dept. of Chemical Engineering and Chemical Technology

    1997-12-31

    A Point of Ayr coal extract, its hydrocracked product and the pyridine solubles/insolubles of a coal tar pitch have been examined using {sup 252}Cf-plasma desorption-mass spectrometry (PDMS) and matrix assisted laser desorption-mass spectrometry (MALDI-MS). Comparison of molecular masses (MMs) between the coal extract and its hydrocracked product by PDMS indicated ranges of masses in the product to be considerably smaller, with number and weight average MMs reduced by approximately a factor of two. MALDI-mass spectra of the same samples indicated a greater reduction in mass. Similar comparison of the pyridine soluble/insoluble fractions of the coal tar pitch showed smaller differences by PD-MS than by MALDI-MS. (orig.)

  12. Direct analysis of samples by mass spectrometry: From elements to bio-molecules using laser ablation inductively couple plasma mass spectrometry and laser desorption/ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Perdian, David C. [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Mass spectrometric methods that are able to analyze solid samples or biological materials with little or no sample preparation are invaluable to science as well as society. Fundamental research that has discovered experimental and instrumental parameters that inhibit fractionation effects that occur during the quantification of elemental species in solid samples by laser ablation inductively coupled plasma mass spectrometry is described. Research that determines the effectiveness of novel laser desorption/ionization mass spectrometric methods for the molecular analysis of biological tissues at atmospheric pressure and at high spatial resolution is also described. A spatial resolution is achieved that is able to analyze samples at the single cell level.

  13. Investigation of tissue inhibitor of metalloproteinases 1 in plasma from colorectal cancer patients and blood donors by surface-enhanced laser desorption/ionization time-of-flight mass spectrometryscopy

    DEFF Research Database (Denmark)

    CASPERSEN, M. B.; Sørensen, N. M.; Iversen, P

    2007-01-01

    in plasma, surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI TOF MS) was used. TIMP-1 measurements of plasma from 16 healthy donors and 14 CRC patients were performed using TIMP-1 monoclonal antibody in SELDI TOF MS and ELISA. SELDI TOF MS applying an antibody to TIMP-1...

  14. Development of a gas-cylinder-free plasma desorption/ionization system for on-site detection of chemical warfare agents.

    Science.gov (United States)

    Iwai, Takahiro; Kakegawa, Ken; Aida, Mari; Nagashima, Hisayuki; Nagoya, Tomoki; Kanamori-Kataoka, Mieko; Miyahara, Hidekazu; Seto, Yasuo; Okino, Akitoshi

    2015-06-02

    A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by negative pressure in the mass spectrometer. High-power density pulsed plasma of 100 kW could be generated by using a microhollow cathode and a laboratory-built high-intensity pulsed power supply (pulse width: 10-20 μs; repetition frequency: 50 Hz). CWAs were desorbed and protonated in the enclosed space adjacent to the plasma source. Protonated sample molecules were introduced to the mass spectrometer by airflow through the discharge region. To evaluate the analytical performance of this device, helium and air plasma were directly irradiated to CWAs in the gas-cylinder-free plasma desorption/ionization system and the protonated molecules were analyzed by using an ion-trap mass spectrometer. A blister agent (nitrogen mustard 3) and nerve gases [cyclohexylsarin (GF), tabun (GA), and O-ethyl S-2-N,N-diisopropylaminoethyl methylphosphonothiolate (VX)] in solution in n-hexane were applied to the Teflon rod and used as test samples, after solvent evaporation. As a result, protonated molecules of CWAs were successfully observed as the characteristic ion peaks at m/z 204, 181, 163, and 268, respectively. In air plasma, the limits of detection were estimated to be 22, 20, 4.8, and 1.0 pmol, respectively, which were lower than those obtained with helium plasma. To achieve quantitative analysis, calibration curves were made by using CWA stimulant dipinacolyl methylphosphonate as an internal standard; straight correlation lines (R(2) = 0.9998) of the peak intensity ratios (target per internal standard) were obtained. Remarkably, GA and GF gave protonated dimer ions, and the ratios of the protonated dimer ions to the protonated

  15. Absolute number densities of helium metastable atoms determined by atomic absorption spectroscopy in helium plasma-based discharges used as ambient desorption/ionization sources for mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Reininger, Charlotte; Woodfield, Kellie [Brigham Young University, Department of Chemistry and Biochemistry, Provo, UT 84602 (United States); Keelor, Joel D.; Kaylor, Adam; Fernández, Facundo M. [Georgia Institute of Technology, School of Chemistry and Biochemistry, Atlanta, GA 30332 (United States); Farnsworth, Paul B., E-mail: paul_farnsworth@byu.edu [Brigham Young University, Department of Chemistry and Biochemistry, Provo, UT 84602 (United States)

    2014-10-01

    The absolute number densities of helium atoms in the 2s {sup 3}S{sub 1} metastable state were determined in four plasma-based ambient desorption/ionization sources by atomic absorption spectroscopy. The plasmas included a high-frequency dielectric barrier discharge (HF-DBD), a low temperature plasma (LTP), and two atmospheric-pressure glow discharges, one with AC excitation and the other with DC excitation. Peak densities in the luminous plumes downstream from the discharge capillaries of the HF-DBD and the LTP were 1.39 × 10{sup 12} cm{sup −3} and 0.011 × 10{sup 12} cm{sup −3}, respectively. Neither glow discharge produced a visible afterglow, and no metastable atoms were detected downstream from the capillary exits. However, densities of 0.58 × 10{sup 12} cm{sup −3} and 0.97 × 10{sup 12} cm{sup −3} were measured in the interelectrode regions of the AC and DC glow discharges, respectively. Time-resolved measurements of metastable atom densities revealed significant random variations in the timing of pulsed absorption signals with respect to the voltage waveforms applied to the discharges. - Highlights: • We determine He metastable number densities for four plasma types • The highest number densities were observed in a dielectric barrier discharge • No helium metastable atoms were observed downstream from the exits of glow discharges.

  16. Absolute number densities of helium metastable atoms determined by atomic absorption spectroscopy in helium plasma-based discharges used as ambient desorption/ionization sources for mass spectrometry

    Science.gov (United States)

    Reininger, Charlotte; Woodfield, Kellie; Keelor, Joel D.; Kaylor, Adam; Fernández, Facundo M.; Farnsworth, Paul B.

    2014-10-01

    The absolute number densities of helium atoms in the 2s 3S1 metastable state were determined in four plasma-based ambient desorption/ionization sources by atomic absorption spectroscopy. The plasmas included a high-frequency dielectric barrier discharge (HF-DBD), a low temperature plasma (LTP), and two atmospheric-pressure glow discharges, one with AC excitation and the other with DC excitation. Peak densities in the luminous plumes downstream from the discharge capillaries of the HF-DBD and the LTP were 1.39 × 1012 cm- 3 and 0.011 × 1012 cm- 3, respectively. Neither glow discharge produced a visible afterglow, and no metastable atoms were detected downstream from the capillary exits. However, densities of 0.58 × 1012 cm- 3 and 0.97 × 1012 cm- 3 were measured in the interelectrode regions of the AC and DC glow discharges, respectively. Time-resolved measurements of metastable atom densities revealed significant random variations in the timing of pulsed absorption signals with respect to the voltage waveforms applied to the discharges.

  17. Study on the plasma proteomic profiling by using surface enhanced laser desorption ionization time of flight mass spectrometry for setting up a diagnostic model of endometriosis

    Institute of Scientific and Technical Information of China (English)

    Liu Hai-yuan; Liu Chun-yan; Leng Jin-hua; Liu Zhu-feng; Sun Da-wei; Zhu Lan; Lang Jing-he; Zheng Yan-hua; Zhang Jian-zhong

    2007-01-01

    Objective: To determine the plasma proteomic profiling by using surface enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS) combined with bioinformatics for screening biomarkers of endometriosis and primarily setting up a diagnostic model of endometriosis.Method.Thirty-six patients with endometriosis diagnosed laparoscopically and thirty-five healthy controls were included in the study.Their serum were analyzed by SELDI and protein chip to generate protein profiling spectra.Student t test was used to compare the peak intensifies of the protein profiling results from the different groups.Biomarker Pattern Software was used to analyze the data between two groups and set up a diagnostic model for endometriosis.Protein profiling spectra from sixteen endometriosis patients and fifteen healthy controls were used double-blindedly to test the efficiency of the diagnostic model and generate the sensitivity and specificity of the model.Result: Fourteen abnormally expressed protein peaks were detected in the plasma of patients with endometriosis (P<0.01).The endometriosis diagnostic model was composed of three protein peaks.It correctly identified 33 of 36 patients with endometriosis and 29 of 35 controls in the training test.In the masked set 14 of 16 patients with endometriosis and 12 of 15 normal controls were correctly identified with sensitivity of 87.5% and specificity of 8o%.Conclusion: Patients with endometriosis have a unique cluster of proteins in plasma detected by SELDI.SELDI provides a new approach for screening novel biomarkers of endometriosis.Its utility in clinical practice need further study.

  18. Analytical development of the sup 252 Cf-plasma desorption mass spectroscopy for the structure analysis of biopolymers and synthetic polymers. Analytische Entwicklung der sup 252 Cf-Plasmadesorptions-Massenspektrometrie zur Strukturanalyse von Biopolymeren und synthetischen Polymeren

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, K.

    1991-01-01

    The dissertation had the following aims: A systematic, analytical development of the plasma desorption method, and applications of the plasma desorption mass spectroscopy (PDMS) in primary structure investigations of polypeptides and proteins, and for the determination of the molecular weight of synthetic polymers. For the analytical development of the PDMS, aspects of main interest were the preparation and characterization techniques, and systematic model investigations of the analytical sensitivity, reproducibility and accuray of the molecular weight determination, as well as of the mixture analysis. The objective in the second part of the dissertation was to show application potentials and limits of the PDMS within the framework of analytical tasks of a primary structure characterization of polypeptides and proteins, as well as with regard to the determination of molecular weight and molecular weight distribution of synthetic polymers. (orig.).

  19. Serum opacity factor unmasks human plasma high-density lipoprotein instability via selective delipidation and apolipoprotein A-I desorption.

    Science.gov (United States)

    Gillard, Baiba K; Courtney, Harry S; Massey, John B; Pownall, Henry J

    2007-11-13

    Human plasma high-density lipoproteins (HDL) are important vehicles in reverse cholesterol transport, the cardioprotective mechanism by which peripheral tissue-cholesterol is transported to the liver for disposal. HDL is the target of serum opacity factor (SOF), a substance produced by Streptococcus pyogenes that turns mammalian serum cloudy. Using a recombinant (r) SOF, we studied opacification and its mechanism. rSOF catalyzes the partial disproportionation of HDL into a cholesteryl ester-rich microemulsion (CERM) and a new HDL-like particle, neo HDL, with the concomitant release of lipid-free (LF)-apo A-I. Opacification is unique; rSOF transfers apo E and nearly all neutral lipids of approximately 100,000 HDL particles into a single large CERM whose size increases with HDL-CE content (r approximately 100-250 nm) leaving a neo HDL that is enriched in PL (41%) and protein (48%), especially apo A-II. rSOF is potent; within 30 min at 37 degrees C, 10 nM rSOF opacifies 4 microM HDL. At respective low and high physiological HDL concentrations, LF-apo A-I is monomeric and tetrameric. CERM formation and apo A-I release have similar kinetics suggesting parallel or rapid sequential steps. According to the reaction products and kinetics, rSOF is a heterodivalent fusogenic protein that uses a docking site to displace apo A-I and bind to exposed CE surfaces on HDL; the resulting rSOF-HDL complex recruits additional HDL with its binding-delipidation site and through multiple fusion steps forms a CERM. rSOF may be a clinically useful and novel modality for improving reverse cholesterol transport. With apo E and a high CE content, CERM could transfer large amounts of cholesterol to the liver for disposal via the LDL receptor; neo HDL is likely a better acceptor of cellular cholesterol than HDL; LF-apo A-I could enhance efflux via the ATP-binding casette transporter ABCA1.

  20. Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis

    Science.gov (United States)

    Senftle, F.E.; Macy, R.J.; Mikesell, J.L.

    1979-01-01

    The fast- and thermal-neutron fluence rates from a 3.7 ??g 252Cf neutron source in a simulated borehole have been measured as a function of the source-to-detector distance using air, water, coal, iron ore-concrete mix, and dry sand as borehole media. Gamma-ray intensity measurements were made for specific spectral lines at low and high energies for the same range of source-to-detector distances in the iron ore-concrete mix and in coal. Integral gamma-ray counts across the entire spectrum were also made at each source-to-detector distance. From these data, the specific neutron-damage rate, and the critical count-rate criteria, we show that in an iron ore-concrete mix (low hydrogen concentration), 252Cf neutron sources of 2-40 ??g are suitable. The source size required for optimum gamma-ray sensitivity depends on the energy of the gamma ray being measured. In a hydrogeneous medium such as coal, similar measurements were made. The results show that sources from 2 to 20 ??g are suitable to obtain the highest gamma-ray sensitivity, again depending on the energy of the gamma ray being measured. In a hydrogeneous medium, significant improvement in sensitivity can be achieved by using faster electronics; in iron ore, it cannot. ?? 1979 North-Holland Publishing Co.

  1. Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis of degradation products after treatment of methylene blue aqueous solution with three-dimensionally integrated microsolution plasma

    Science.gov (United States)

    Shirafuji, Tatsuru; Nomura, Ayano; Hayashi, Yui; Tanaka, Kenji; Goto, Motonobu

    2016-01-01

    Methylene blue can be degraded in three-dimensionally integrated microsolution plasma. The degradation products have been analyzed by matrix-assisted laser desorption ionization time-of-flight (MALDI TOF) mass spectrometry to understand the degradation mechanisms. The results of MALDI TOF mass spectrometry have shown that sulfoxide is formed at the first stage of the oxidation. Then, partial oxidation proceeds on the methyl groups left on the sulfoxide. The sulfoxide is subsequently separated to two benzene derivatives. Finally, weak functional groups are removed from the benzene derivatives.

  2. Protective coatings preventing hydrogen desorption from titanium during ion irradiation

    Science.gov (United States)

    Evsin, A. E.; Begrambekov, L. B.; Dovganyuk, S. S.; Kaplevsky, A. S.; Shutikova, M. I.

    2017-05-01

    Effect of yttria and titanium nitride coatings on features of deuterium desorption from titanium layer is investigated. It is shown that both coatings significantly raise the temperature of maximum of deuterium thermal desorption from titanium under linear heating and prevent desorption under prolonged keeping at the operating temperature of a neutron tube target. However, under irradiation with ions of H2 + O2 plasma the barrier properties of titanium nitride appear to degrade.

  3. Water desorption from nanostructured graphite surfaces.

    Science.gov (United States)

    Clemens, Anna; Hellberg, Lars; Grönbeck, Henrik; Chakarov, Dinko

    2013-12-21

    Water interaction with nanostructured graphite surfaces is strongly dependent on the surface morphology. In this work, temperature programmed desorption (TPD) in combination with quadrupole mass spectrometry (QMS) has been used to study water ice desorption from a nanostructured graphite surface. This model surface was fabricated by hole-mask colloidal lithography (HCL) along with oxygen plasma etching and consists of a rough carbon surface covered by well defined structures of highly oriented pyrolytic graphite (HOPG). The results are compared with those from pristine HOPG and a rough (oxygen plasma etched) carbon surface without graphite nanostructures. The samples were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TPD experiments were conducted for H2O coverages obtained after exposures between 0.2 and 55 langmuir (L) and reveal a complex desorption behaviour. The spectra from the nanostructured surface show additional, coverage dependent desorption peaks. They are assigned to water bound in two-dimensional (2D) and three-dimensional (3D) hydrogen-bonded networks, defect-bound water, and to water intercalated into the graphite structures. The intercalation is more pronounced for the nanostructured graphite surface in comparison to HOPG surfaces because of a higher concentration of intersheet openings. From the TPD spectra, the desorption energies for water bound in 2D and 3D (multilayer) networks were determined to be 0.32 ± 0.06 and 0.41 ± 0.03 eV per molecule, respectively. An upper limit for the desorption energy for defect-bound water was estimated to be 1 eV per molecule.

  4. Fatty acid profiling of raw human plasma and whole blood using direct thermal desorption combined with gas chromatography-mass spectrometry

    NARCIS (Netherlands)

    Akoto, Lawrence; Vreuls, Rene J. J.; Irth, Hubertus; Pel, Roel; Stellaard, Frans

    2008-01-01

    Gas chromatography (GC) has in recent times become an important tool for the fatty acid profiling of human blood and plasma. An at-line procedure used in the fatty acid profiling of whole/intact aquatic micro-organisms without any sample preparation was adapted for this work. A direct thermal

  5. Fatty acid profiling of raw human plasma and whole blood using direct thermal desorption combined with gas chromatography–mass spectrometry

    NARCIS (Netherlands)

    Akoto, L.; Vreuls, R.J.J.; Irth, H.; Pel, R.; Stellaard, F.

    2008-01-01

    Gas chromatography (GC) has in recent times become an important tool for the fatty acid profiling of human blood and plasma. An at-line procedure used in the fatty acid profiling of whole/intact aquatic micro-organisms without any sample preparation was adapted for this work. A direct thermal

  6. Laser Desorption Ionization Quadrupole Ion Trap Time-of-Flight Mass Spectrometry of Au m Fe n +/- Clusters Generated from Gold-Iron Nanoparticles and their Giant Nanoflowers. Electrochemical and/or Plasma Assisted Synthesis

    Science.gov (United States)

    Mawale, Ravi Madhukar; Ausekar, Mayuri Vilas; Pavliňák, David; Galmiz, Oleksandr; Kubáček, Pavel; Havel, Josef

    2017-02-01

    Gold nanoparticles (NP) with average diameter 100 nm synthesized from tetrachloroauric acid solution using stainless steel as a reducing agent were found to contain iron. Applying simultaneously high frequency (HF) plasma discharge in solution during the electrochemical reduction, giant gold-iron nanoflowers with average size 1000-5000 nm were formed. Scanning electron microscopy (SEM) shows the morphology of the nanopowders produced as polygonal yet nearly spherical, whereas iron content in both products determined by energy dispersive X-ray analysis (EDX) was found to be at 2.5 at. %. Laser desorption ionization (LDI) of both nanomaterials and mass spectrometric analysis show the formation of Au m Fe n +/- ( m = 1-35; n = 1-3) clusters. Structure of few selected clusters in neutral or monocharged forms were computed by density functional theory (DFT) calculations and it was found that typical distances of an iron nucleus from adjacent gold nuclei lie in the interval 2.5 to 2.7 Å. Synthetized Au-Fe nanoparticles were found stable for at least 2 mo at room temperature (even in aqueous solution) without any stabilizing agent. Produced Au-Fe nanoparticles in combination with standard MALDI matrices enhance ionization of peptides and might find use in nanomedicine.

  7. Analysis of metal-binding proteins separated by non-denaturating gel electrophoresis using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

    Science.gov (United States)

    Becker, J Susanne; Mounicou, Sandra; Zoriy, Miroslav V; Becker, J Sabine; Lobinski, Ryszard

    2008-09-15

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have become established as very efficient and sensitive biopolymer and elemental mass spectrometric techniques for studying metal-binding proteins (metalloproteins) in life sciences. Protein complexes present in rat tissues (liver and kidney) were separated in their native state in the first dimension by blue native gel electrophoresis (BN-PAGE). Essential and toxic metals, such as zinc, copper, iron, nickel, chromium, cadmium and lead, were detected by scanning the gel bands using quadrupole LA-ICP-MS with and without collision cell as a microanalytical technique. Several proteins were identified by using MALDI-TOF-MS together with a database search. For example, on one protein band cut from the BN-PAGE gel and digested with the enzyme trypsin, two different proteins - protein FAM44B and cathepsin B precursor - were identified. By combining biomolecular and elemental mass spectrometry, it was possible to characterize and identify selected metal-binding rat liver and kidney tissue proteins.

  8. Beryllium Desorption from Sediments

    Science.gov (United States)

    Boschi, V.; Willenbring, J. K.

    2015-12-01

    Beryllium isotopes have provided a useful tool in the field of geochronology and geomorphology over the last 25 years. The amount of cosmogenic meteoric 10Be and native 9Be absorbed to soils often scales with the residence time and chemical weathering of sediments in a landscape, respectively. Thus, the concentrations in river sediment may be used to quantify the denudation of specific watersheds. When deposited in ocean sediment, these concentrations are thought to record the history of denudation on Earth over the last ~10 Ma. The use of both isotopes often relies on the premise of beryllium retention to sediment surfaces in order to preserve a landscape's erosion and weathering signature. Changes in setting, en route from the soil to fluvial system to the ocean, can cause beryllium desorption and may preclude some applications of the 10Be/9Be system. Four mechanisms were tested to determine the desorption potential of beryllium including a reduction in pH, an increase in ionic strength and complexation with soluble organic and inorganic species. These processes have the potential to mobilize beryllium into solution. For example, by both reducing the pH and increasing the ionic strength, competition for adsorption sites increases, potentially liberating beryllium from the sediment surface. In addition, organic and inorganic ligands can complex beryllium causing it to become mobilized. To determine which of these alterations influence beryllium desorption and to quantify the effect, we prepared separate solutions of beryllium bound to minerals and organic compounds and measured beryllium concentrations in solution before and after adjusting the pH, ionic strength, and changing inorganic and organic ligand concentrations. We conclude from our observations that overall, beryllium sorbed to organic compounds was more resistant to desorption relative to mineral-associated beryllium. Among the methods tested, a reduction in pH resulted in the greatest amount of

  9. Keno-Nr a Monte Carlo Code Simulating the Californium -252-SOURCE-DRIVEN Noise Analysis Experimental Method for Determining Subcriticality

    Science.gov (United States)

    Ficaro, Edward Patrick

    The ^{252}Cf -source-driven noise analysis (CSDNA) requires the measurement of the cross power spectral density (CPSD) G_ {23}(omega), between a pair of neutron detectors (subscripts 2 and 3) located in or near the fissile assembly, and the CPSDs, G_{12}( omega) and G_{13}( omega), between the neutron detectors and an ionization chamber 1 containing ^{252}Cf also located in or near the fissile assembly. The key advantage of this method is that the subcriticality of the assembly can be obtained from the ratio of spectral densities,{G _sp{12}{*}(omega)G_ {13}(omega)over G_{11 }(omega)G_{23}(omega) },using a point kinetic model formulation which is independent of the detector's properties and a reference measurement. The multigroup, Monte Carlo code, KENO-NR, was developed to eliminate the dependence of the measurement on the point kinetic formulation. This code utilizes time dependent, analog neutron tracking to simulate the experimental method, in addition to the underlying nuclear physics, as closely as possible. From a direct comparison of simulated and measured data, the calculational model and cross sections are validated for the calculation, and KENO-NR can then be rerun to provide a distributed source k_ {eff} calculation. Depending on the fissile assembly, a few hours to a couple of days of computation time are needed for a typical simulation executed on a desktop workstation. In this work, KENO-NR demonstrated the ability to accurately estimate the measured ratio of spectral densities from experiments using capture detectors performed on uranium metal cylinders, a cylindrical tank filled with aqueous uranyl nitrate, and arrays of safe storage bottles filled with uranyl nitrate. Good agreement was also seen between simulated and measured values of the prompt neutron decay constant from the fitted CPSDs. Poor agreement was seen between simulated and measured results using composite ^6Li-glass-plastic scintillators at large subcriticalities for the tank of uranyl nitrate. It is believed that the response of these detectors is not well known and is incorrectly modeled in KENO-NR. In addition to these tests, several benchmark calculations were also performed to provide insight into the properties of the point kinetic formulation.

  10. Radiological Characterization Technical Report on Californium-252 Sealed Source Transuranic Debris Waste for the Off-Site Source Recovery Project at Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-04-24

    This document describes the development and approach for the radiological characterization of Cf-252 sealed sources for shipment to the Waste Isolation Pilot Plant. The report combines information on the nuclear material content of each individual source (mass or activity and date of manufacture) with information and data on the radionuclide distributions within the originating nuclear material. This approach allows for complete and accurate characterization of the waste container without the need to take additional measurements. The radionuclide uncertainties, developed from acceptable knowledge (AK) information regarding the source material, are applied to the summed activities in the drum. The AK information used in the characterization of Cf-252 sealed sources has been qualified by the peer review process, which has been reviewed and accepted by the Environmental Protection Agency.

  11. Thermal Desorption of Helium Implanted in Tungsten at RT

    Institute of Scientific and Technical Information of China (English)

    ZHANGFu; XUZengyu; LIUXiang; CHENJiming; XUYing; N.Yoshida; H.Iwakiri

    2002-01-01

    Tungsten is envisaged as one of the main candidate materials for divertor plate of ITER and future fusion reactors. Due to D-T reaction, PFMs would suffer helium irradiation from plasma additional to the high heat loads. Helium retention and thermal desorption behavior are largely concerned.

  12. Monomer Adsorption-Desorption Processes

    Institute of Scientific and Technical Information of China (English)

    KE Jian-Hong; LIN Zhen-Quan; CHEN Xiao-Shuang

    2009-01-01

    We propose an adsorption-desorption model for a deposit growth system, in which the adsorption and desorption of particles coexist. By means of the generalized rate equation we investigate the cluster (island) size distribution in the dynamic equilibrium state. The results show that the evolution behaviour of the system depends crucially on the details of the rate kernels. The cluster size distribution can take the ecale-frse power-law form in some cases, while it grows exponentially with size in other cases.

  13. Isotope effects on desorption kinetics of hydrogen isotopes implanted into stainless steel by glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, M.; Kondo, M.; Noda, N. [Hydrogen Isotope Research Center, University of Toyama, Gofuku, Toyama (Japan); Tanaka, M.; Nishimura, K. [National Institute for Fusion Science, Toki-shi, Gifu (Japan)

    2015-03-15

    In a fusion device the control of fuel particles implies to know the desorption rate of hydrogen isotopes by the plasma-facing materials. In this paper desorption kinetics of hydrogen isotopes implanted into type 316L stainless steel by glow discharge have been studied by experiment and numerical calculation. The temperature of a maximum desorption rate depends on glow discharge time and heating rate. Desorption spectra observed under various experimental conditions have been successfully reproduced by numerical simulations that are based on a diffusion-limited process. It is suggested, therefore, that desorption rate of a hydrogen isotope implanted into the stainless steel is limited by a diffusion process of hydrogen isotope atoms in bulk. Furthermore, small isotope effects were observed for the diffusion process of hydrogen isotope atoms. (authors)

  14. SPS Ion Induced Desorption Experiment

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    This experiment will give a study about the induced desorption from heavy ion (Indium ion run from week 45 in SPS T4-H8 area) impacting LHC type graphite collimator. 4 different samples are located in the 4 chambers 90° one to each other: pure graphite, graphite with copper coating, graphite with NEG coating, 316LN stainless steal (reference).

  15. Effect of Ultrasound on Desorption Equilibrium

    Institute of Scientific and Technical Information of China (English)

    秦炜; 原永辉; 戴猷元

    2001-01-01

    Effects of ultrasound on intensification of separation process were investigated through the experiment of desorption equilibrium behavior. Tri-butyl phosphate (TBP) on NKA-X resin and phenol on a solvent impregnated resin, CL-TBP resin, were used for desorption processes. The desorption rate was measured with and without ultrasound. Desorption equilibrium was studied under various ultrasonic power densities or thermal infusion. Results showed that the desorption rate with ultrasound was much higher than that with normal thermal infusion. Both ultrasound and thermal infusion broke the desorption equilibrium existed at room temperature. However, after the systems were cooled down, the amount of solute desorbed in the liquid phase in the presence of ultrasound was much higher than that at the temperature corresponding to the same ultrasound power. It is proved that the initial desorption equilibrium was broken as a result of the spot energy effect of ultrasound.

  16. Hydrogen desorption from nanostructured magnesium hydride composites

    Directory of Open Access Journals (Sweden)

    Brdarić Tanja P.

    2007-01-01

    Full Text Available The influence of 3d transition metal addition (Fe, Co and Ni on the desorption properties of magnesium hydride were studied. The ball milling of MgH2-3d metal blends was performed under Ar. Microstructural and morphological characterization were performed by XRD and SEM analysis, while the hydrogen desorption properties were investigated by DSC. The results show a strong correlation between the morphology and thermal stability of the composites. The complex desorption behavior (the existence of more than one desorption peak was correlated with the dispersion of the metal additive particles that appear to play the main role in the desorption. The desorption temperature can be reduced by more than 100 degrees if Fe is added as additive. The activation energy for H2 desorption from the MgH2-Fe composite is 120 kJ/mol, implying that diffusion controls the dehydration process.

  17. Investigation of tissue inhibitor of metalloproteinases 1 in plasma from colorectal cancer patients and blood donors by surface-enhanced laser desorption/ionization time-of-flight mass spectrometryscopy

    DEFF Research Database (Denmark)

    CASPERSEN, M. B.; Sørensen, N. M.; Iversen, P

    2007-01-01

    Early detection of colorectal cancer (CRC) improves patient survival. Plasma tissue inhibitor of metalloproteinases 1 (TIMP-1) measurements by enzyme-linked immunosorbent assay (ELISA) have been suggested as a new method for the early detection of CRC. To further investigate the nature of TIMP-1...... revealed that human plasma TIMP-1 has a mass of 25.1 kDa and exhibits several isoforms. Both methods showed increased plasma TIMP-1 values for cancer patients as compared to healthy individuals. The p values for the separation of the groups were 0.0019 for ELISA and

  18. Threshold character of temperatures on deuterium desorption from the Mg-Zr composite

    Science.gov (United States)

    Neklyudov, I. M.; Morozov, O. M.; Kulish, V. G.; Zhurba, V. I.; Lomino, N. S.; Ovcharenko, V. D.; Kuprin, O. S.

    2011-06-01

    The plasma evaporation-sputtering method was used to manufacture composite materials of the Mg-Zr system. The ion-implanted deuterium desorption temperature variations depending on the component concentrations were studied. It has been established that the introduction of a Zr impurity to magnesium leads to the significant decrease of the deuterium desorption temperature (~400K) as compared to the release from Mg samples. A step-like form of the curve of the deuterium desorption temperature testifies to presence of two various structural conditions at composite Mg-Zr depending on the relation of components. The hydrogen desorption data obtained using Mg-Zr composites can be used for the further invrstigations into the hydrogen storage materials containing chemical elements with a low solubility in the alloy components.

  19. Threshold character of temperatures on deuterium desorption from the Mg-Zr composite

    Energy Technology Data Exchange (ETDEWEB)

    Neklyudov, I M; Morozov, O M; Kulish, V G; Zhurba, V I; Lomino, N S; Ovcharenko, V D; Kuprin, O S, E-mail: morozov@kipt.kharkov.ua [National Science Center ' Kharkov Institute of Physics and Technology' , 61108 Kharkov (Ukraine)

    2011-06-23

    The plasma evaporation-sputtering method was used to manufacture composite materials of the Mg-Zr system. The ion-implanted deuterium desorption temperature variations depending on the component concentrations were studied. It has been established that the introduction of a Zr impurity to magnesium leads to the significant decrease of the deuterium desorption temperature ({approx}400K) as compared to the release from Mg samples. A step-like form of the curve of the deuterium desorption temperature testifies to presence of two various structural conditions at composite Mg-Zr depending on the relation of components. The hydrogen desorption data obtained using Mg-Zr composites can be used for the further invrstigations into the hydrogen storage materials containing chemical elements with a low solubility in the alloy components.

  20. Investigation of tissue inhibitor of metalloproteinases 1 in plasma from colorectal cancer patients and blood donors by surface-enhanced laser desorption/ionization time-of-flight mass spectrometryscopy

    DEFF Research Database (Denmark)

    CASPERSEN, M. B.; Sørensen, N. M.; Iversen, P

    2007-01-01

    Early detection of colorectal cancer (CRC) improves patient survival. Plasma tissue inhibitor of metalloproteinases 1 (TIMP-1) measurements by enzyme-linked immunosorbent assay (ELISA) have been suggested as a new method for the early detection of CRC. To further investigate the nature of TIMP-1...

  1. Helium concentration measurement in tungsten fuzz-like nanostructures by means of thermal desorption spectroscopy

    NARCIS (Netherlands)

    Gasparyan, Y.; Efimov, V.; Bystrov, K.

    2016-01-01

    The concentration of helium in tungsten fuzz-like nanostructures has been measured by means of thermal desorption spectroscopy. Fuzz was formed on the W surface under intensive plasma irradiation at 1500 K. The helium content was measured first in the as-irradiated sample, and then in a similar samp

  2. Magic-angle thermal desorption mass spectroscopy

    Science.gov (United States)

    Pauls, Steven W.; Campbell, Charles T.

    1990-02-01

    Accurate quantitative measurements of desorption rates or adsorbate coverages in thermal desorption mass spectroscopy (TDS) using line-of-sight mass spectrometers are hindered by the fact that the angular distributions of desorption flux can vary widely from desorbate to desorbate, ranging from cos 1ø to cos 9 ø for most species studied to date (ø = polar angle from surface normal). These differences can easily lead to errors exceeding 400% in measuring the relative desorption rates of different species. We show here that, by placing the mass spectrometer's ion source or entrance aperture at a "magic-angle" ø mthese errors can be reduced to less than 26% maximum deviation (or ± 7% standard deviation). Depending upon the sample-to-detector distance, ø m varies from ~ 42° to 34°. It is recommended that TDS experiments be performed at this "magic-angle" for improvement in the quantitative accuracy of coverage or rate measurements.

  3. Infrared laser desorption/ionization on silicon.

    Science.gov (United States)

    Bhattacharya, Sucharita H; Raiford, Timothy J; Murray, Kermit K

    2002-05-01

    Laser desorption/ionization from a single-crystal silicon surface was performed using a laser operating in the 3-microm region of the mid-infrared. Analyte molecules up to 6 kDa were ionized with no added matrix. As with ultraviolet desorption/ionization from porous silicon (DIOS), IR laser desorption from silicon does not produce matrix ions that can interfere with analysis of low-mass analytes. However, in contrast to UV DIOS, silicon porosity or roughness is not required for ionization using an IR laser. Mass spectra were obtained in the wavelength range between 2.8 and 3.5 microm, which is consistent with energy absorption by a hydrogen-bonded OH group. A mechanism based on desorption of adsorbed solvent molecules is postulated.

  4. Hydrocarbon analysis using desorption atmospheric pressure chemical ionization

    KAUST Repository

    Jjunju, Fred Paul Mark

    2013-07-01

    Characterization of the various petroleum constituents (hydronaphthalenes, thiophenes, alkyl substituted benzenes, pyridines, fluorenes, and polycyclic aromatic hydrocarbons) was achieved under ambient conditions without sample preparation by desorption atmospheric pressure chemical ionization (DAPCI). Conditions were chosen for the DAPCI experiments to control whether ionization was by proton or electron transfer. The protonated molecule [M+H]+ and the hydride abstracted [MH]+ form were observed when using an inert gas, typically nitrogen, to direct a lightly ionized plasma generated by corona discharge onto the sample surface in air. The abundant water cluster ions generated in this experiment react with condensed-phase functionalized hydrocarbon model compounds and their mixtures at or near the sample surface. On the other hand, when naphthalene was doped into the DAPCI gas stream, its radical cation served as a charge exchange reagent, yielding molecular radical cations (M+) of the hydrocarbons. This mode of sample ionization provided mass spectra with better signal/noise ratios and without unwanted side-products. It also extended the applicability of DAPCI to petroleum constituents which could not be analyzed through proton transfer (e.g., higher molecular PAHs such as chrysene). The thermochemistry governing the individual ionization processes is discussed and a desorption/ionization mechanism is inferred. © 2012 Elsevier B.V.

  5. Desorption of 137Cs+ from mosses

    Directory of Open Access Journals (Sweden)

    OLGICA NEDIC

    2002-09-01

    Full Text Available Mosses are biomonitors that accumulate large amounts of various pollutants, including radionuclides. In this work we investigated the possibility of 137Cs extraction from mosses, as well as the significance of species specificity on the efficiency of 137Cs desorption. Salt and acid solutions were used as extraction media. It was shown that a 5 % solution of both ammonium oxalate and phosphoric acid was able to desorb 81.8 % of 137Cs+ from Homalothecium sericeum, which was 39.9 % more than desorption from water. At the same time, most of the desorbed 137Cs+ was incorporated in crystals that precipitated from the solution. An interspecies difference in respect to 137Cs+ desorption was noticed.

  6. Adsorption and Desorption of Methiopyrsulfuron in Soils

    Institute of Scientific and Technical Information of China (English)

    WU Chun-Xian; WANG Jin-Jun; ZHANG Su-Zhi; ZHANG Zhong-Ming

    2011-01-01

    Methiopyrsulfuron is a new low-rate sulfonylurea herbicide for weed control in wheat; however, there is a lack of published information on its behavior in soils. In this study, methiopyrsulfuron adsorption and desorption were measured in seven soils sampled from Heilongjiang, Shandong, Jiangxi, Sichuan, Anhui, and Chongqing provinces of China using a batch equilibrium method. The Freundlich equation was used to described its adsorption and desorption. Adsorption isotherms were nonlinear with the values of Kf-ads, the Freundlich empirical constant indicative of the adsorption capacity,ranging from 0.75 to 2.46, suggesting that little of this herbicide was adsorbed by any of the seven soils. Soil pH and organic matter content (OM) were the main factors influencing adsorption; adsorption was negatively correlated with pH and positively correlated with OM. Methiopyrsulfuron desorption was hysteretic on the soils with high OM content and low pH.

  7. Ionic Adsorption and Desorption of CNT Nanoropes

    Directory of Open Access Journals (Sweden)

    Jun-Jun Shang

    2016-09-01

    Full Text Available A nanorope is comprised of several carbon nanotubes (CNTs with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method based on classical electrostatic theory. The electrostatic interactions among charged carbon atoms are calculated by using the Coulomb law. It was found here that the charged nanorope can adsorb heavy metal ions, and the adsorption and desorption can be realized by controlling the strength of applied electric field. The distance between the ions and the nanorope as well as the amount of ions have an effect on the adsorption capacity of the nanorope. The desorption process takes less time than that of adsorption. The study indicates that the CNT nanorope can be used as a core element of devices for sewage treatment.

  8. Electronic Desorption of gas from metals

    Energy Technology Data Exchange (ETDEWEB)

    Molvik, A W; Kollmus, H; Mahner, E; Covo, M K; Bender, M; Bieniosek, F M; Kramer, A; Kwan, J; Prost, L; Seidl, P A; Westenskow, G

    2006-11-02

    During heavy ion operation in several particle accelerators world-wide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion induced gas desorption scales with the electronic energy loss (dE{sub e}/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  9. Quantum theory of laser-stimulated desorption

    Science.gov (United States)

    Slutsky, M. S.; George, T. F.

    1978-01-01

    A quantum theory of laser-stimulated desorption (LSDE) is presented and critically analyzed. It is shown how LSDE depends on laser-pulse characteristics and surface-lattice dynamics. Predictions of the theory for a Debye model of the lattice dynamics are compared to recent experimental results.

  10. A microsystems enabled field desorption source.

    Energy Technology Data Exchange (ETDEWEB)

    Hertz, Kristin L.; Resnick, Paul James; Schwoebel, Paul R. (University of New Mexico, Albuquerque, NM); Holland, Christopher E. (SRI International, Menlo Park, CA); Chichester, David L. (Idaho National Laboratory, Idaho Falls, ID)

    2010-07-01

    Technologies that have been developed for microelectromechanical systems (MEMS) have been applied to the fabrication of field desorption arrays. These techniques include the use of thick films for enhanced dielectric stand-off, as well as an integrated gate electrode. The increased complexity of MEMS fabrication provides enhanced design flexibility over traditional methods.

  11. Product desorption limitations in selective photocatalytic oxidation

    NARCIS (Netherlands)

    Renckens, T.J.A.; Almeida, A.R.; Damen, M.R.; Kreutzer, M.T.; Mul, G.

    2010-01-01

    The rate of photocatalytic processes can be significantly improved if strongly bound products rapidly desorb to free up active sites. This paper deals with the rate of desorption of cyclohexanone, the product of the liquid-phase photo-oxidation of cyclohexane. Dynamic step-response and pulse-respons

  12. Residence time dependent desorption of Staphylococcus epidermidis from hydrophobic and hydrophilic substrata

    NARCIS (Netherlands)

    Boks, Niels P.; Kaper, Hans J.; Norde, Willem; Busscher, Henk J.; van der Mei, Henny C.

    2008-01-01

    Adhesion and desorption are simultaneous events during bacterial adhesion to surfaces. although desorption is far less studied than adhesion. Here, desorption of Staphylococcus epidermidis from substratum surfaces is demonstrated to be residence time dependent. Initial desorption rate coefficients

  13. Residence time dependent desorption of Staphylococcus epidermidis from hydrophobic and hydrophilic substrata

    NARCIS (Netherlands)

    Boks, Niels P.; Kaper, Hans J.; Norde, Willem; Busscher, Henk J.; van der Mei, Henny C.

    2008-01-01

    Adhesion and desorption are simultaneous events during bacterial adhesion to surfaces. although desorption is far less studied than adhesion. Here, desorption of Staphylococcus epidermidis from substratum surfaces is demonstrated to be residence time dependent. Initial desorption rate coefficients w

  14. Plutonium sorption and desorption behavior on bentonite.

    Science.gov (United States)

    Begg, James D; Zavarin, Mavrik; Tumey, Scott J; Kersting, Annie B

    2015-03-01

    Understanding plutonium (Pu) sorption to, and desorption from, mineral phases is key to understanding its subsurface transport. In this work we study Pu(IV) sorption to industrial grade FEBEX bentonite over the concentration range 10(-7)-10(-16) M to determine if sorption at typical environmental concentrations (≤10(-12) M) is the same as sorption at Pu concentrations used in most laboratory experiments (10(-7)-10(-11) M). Pu(IV) sorption was broadly linear over the 10(-7)-10(-16) M concentration range during the 120 d experimental period; however, it took up to 100 d to reach sorption equilibrium. At concentrations ≥10(-8) M, sorption was likely affected by additional Pu(IV) precipitation/polymerization reactions. The extent of sorption was similar to that previously reported for Pu(IV) sorption to SWy-1 Na-montmorillonite over a narrower range of Pu concentrations (10(-11)-10(-7) M). Sorption experiments with FEBEX bentonite and Pu(V) were also performed across a concentration range of 10(-11)-10(-7) M and over a 10 month period which allowed us to estimate the slow apparent rates of Pu(V) reduction on a smectite-rich clay. Finally, a flow cell experiment with Pu(IV) loaded on FEBEX bentonite demonstrated continued desorption of Pu over a 12 day flow period. Comparison with a desorption experiment performed with SWy-1 montmorillonite showed a strong similarity and suggested the importance of montorillonite phases in controlling Pu sorption/desorption reactions on FEBEX bentonite.

  15. Thermal desorption of deuterium implanted into beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Markin, A.V.; Chernikov, V.N.; Zakharov, A.P. [Institute of Physical Chemistry, Moscow (Russian Federation)] [and others

    1995-09-01

    By means of TDS measurements it is shown that the desorption of deuterium from Be implanted with 5 keV D ions to fluences, {Phi}, from 1x10{sup 20} D/m{sup 2} to 1x10{sup 21} D/m{sup 2} proceeds in one high temperature stage B, while at {Phi} {ge} 1.2x10{sup 21}D/m{sup 2} one more stage A is added. The desorption maximum A is narrow and consists of two peaks A{sub 1} and A{sub 2} at about 460 K and 490 K, respectively. Peak A{sub 1} is attributed to the desorption of deuterium from the walls of opened channels formed under D ion implantation. Peak {sub A}2 is a consequence of the opening of a part of closed bubbles/channels to the outer surface. The position of maximum B shifts noticeably and nonsteadily on the fluence in a range from 850 to 1050 K. The origin of this maximum is the liberation of D atoms bound at vacancy complexes discussed previously by Wampler. The dependence of Tm(B) on the fluence is governed by the interaction of freely migrating D atoms with partly opened or fully closed gas cavity arrangements which are created under temperature ramping, but differently in specimens implanted with D ions to different fluences.

  16. Lead sorption-desorption from organic residues.

    Science.gov (United States)

    Duarte Zaragoza, Victor M; Carrillo, Rogelio; Gutierrez Castorena, Carmen M

    2011-01-01

    Sorption and desorption are mechanisms involved in the reduction of metal mobility and bioavailability in organic materials. Metal release from substrates is controlled by desorption. The capacity of coffee husk and pulp residues, vermicompost and cow manure to adsorb Pb2+ was evaluated. The mechanisms involved in the sorption process were also studied. Organic materials retained high concentrations of lead (up to 36,000 mg L(-1)); however, the mechanisms of sorption varied according to the characteristics of each material: degree of decomposition, pH, cation exchange capacity and percentage of organic matter. Vermicompost and manure removed 98% of the Pb from solution. Lead precipitated in manure and vermicompost, forming lead oxide (PbO) and lead ferrite (PbFe4O7). Adsorption isotherms did not fit to the typical Freundlich and Langmuir equations. Not only specific and non-specific adsorption was observed, but also precipitation and coprecipitation. Lead desorption from vermicompost and cow manure was less than 2%. For remediation of Pb-polluted sites, the application of vermicompost and manure is recommended in places with alkaline soils because Pb precipitation can be induced, whereas coffee pulp residue is recommended for acidic soils where Pb is adsorbed.

  17. Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Masashi Shimada; M. Hara; T. Otsuka; Y. Oya; Y. Hatano

    2014-05-01

    Accurately estimating tritium retention in plasma facing components (PFCs) and minimizing its uncertainty are key safety issues for licensing future fusion power reactors. D-T fusion reactions produce 14.1 MeV neutrons that activate PFCs and create radiation defects throughout the bulk of the material of these components. Recent studies show that tritium migrates and is trapped in bulk (>> 10 µm) tungsten beyond the detection range of nuclear reaction analysis technique [1-2], and thermal desorption spectroscopy (TDS) technique becomes the only established diagnostic that can reveal hydrogen isotope behavior in in bulk (>> 10 µm) tungsten. Radiation damage and its recovery mechanisms in neutron-irradiated tungsten are still poorly understood, and neutron-irradiation data of tungsten is very limited. In this paper, systematic investigations with repeated plasma exposures and thermal desorption are performed to study defect annealing and thermal desorption of deuterium in low dose neutron-irradiated tungsten. Three tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to high flux (ion flux of (0.5-1.0)x1022 m-2s-1 and ion fluence of 1x1026 m-2) deuterium plasma at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy (TDS) was performed with a ramp rate of 10 °C/min up to 900 °C, and the samples were annealed at 900 °C for 0.5 hour. These procedures were repeated three (for 100 and 200 °C samples) and four (for 500 °C sample) times to uncover damage recovery mechanisms and its effects on deuterium behavior. The results show that deuterium retention decreases approximately 90, 75, and 66 % for 100, 200, and 500 °C, respectively after each annealing. When subjected to the same TDS recipe, the desorption temperature shifts from 800 °C to 600 °C after 1st annealing

  18. Experimental study on effects of CBM temperature-rising desorption

    Institute of Scientific and Technical Information of China (English)

    MA Dong-min; LIN Ya-bing

    2012-01-01

    To study the effects of CBM (coal bed methane) temperature-rising desorption,isothermal adsorption/desorption experiments on three ranks (anthracite,coking coal and lignite) of coal at different temperatures were designed based on the traditional CBM decompression desorption.The experimental results indicate that temperature-rising desorption is more effective in high-rank coal,and ever-increasing temperature of high-rank coal reservoir can reduce the negative effects of coal matrix shrinkage in the process of production and improve the permeability of the coal reservoir as well.It is also revealed that the technique of temperature-rising desorption applied in higher-rank coal reservoir can enhance CBM recovery ratio.This study provided theoretical support for the application of temperature-rising desorption technique in practical discharging and mining projects,which can effectively tackle the gas production bottleneck problem.

  19. The effect of selective desorption mechanisms during interstellar ice formation

    CERN Document Server

    Kalvans, Juris

    2015-01-01

    Major components of ices on interstellar grains in molecular clouds - water and carbon oxides - occur at various optical depths. This implies that selective desorption mechanisms are at work. An astrochemical model of a contracting low-mass molecular cloud core is presented. Ice was treated as consisting of the surface and three subsurface layers (sublayers). Photodesorption, reactive desorption, and indirect reactive desorption were investigated. The latter manifests itself through desorption from H+H reaction on grains. Desorption of shallow subsurface species was included. Modeling results suggest the existence of a "photon-dominated ice" during the early phases of core contraction. Subsurface ice is chemically processed by interstellar photons, which produces complex organic molecules. Desorption from the subsurface layer results in high COM gas-phase abundances at Av = 2.4...10mag. This may contribute towards an explanation for COM observations in dark cores. It was found that photodesorption mostly gove...

  20. Nonisothermal desorption of droplets of complex compositions

    Directory of Open Access Journals (Sweden)

    Nakoryakov Vladimir E.

    2012-01-01

    Full Text Available This paper presents the process of nonstationary evaporation of aqueous solutions of LiBr-H2O, CaCl2-H2O, NaCl-H2O droplets on a horizontal heating surface. The following typical stages of heat and mass transfer depending on wall temperature have been considered: evaporation below boiling temperature and nucleate boiling. The significant decrease in desorption intensity with a rise of initial mass concentration of salt has been observed. Formation of a surface crystallization front at evaporation of a droplet has been detected. We have developed the experimental method for direct measurements of the mass of evaporating droplet.

  1. Threshold character of temperatures on deuterium thermal desorption in Mg-V composite grown atom-by-atom

    Science.gov (United States)

    Neklyudov, I. M.; Morozov, O. M.; Kulish, V. G.; Zhurba, V. I.; Galitskiy, A. G.; Lomino, N. S.; Kuprin, A. S.; Ovcharenko, V. D.; Reshetnyak, E. N.

    2012-08-01

    The plasma evaporation-sputtering method was applied to make composite materials of the Mg-V system. The ion-implanted deuterium desorption temperature variations as a function of the component concentration were studied. It has been established that, by introducing vanadium into magnesium, the deuterium desorption temperature can be appreciably decreased (to 300-330 K) in comparison with the case of deuterium desorption from magnesium (~800 K). A step-like form of the curve of deuterium desorption temperature evidences on the presence of two different structure states of the Mg-V system depending on the ratio of components. The deuterium temperature decrease can be caused by filamentary inclusions formed, in the process of composite making and annealing, by the insoluble component (vanadium) atoms providing the deuterium diffusion from the sample at a lower temperature (channels for deuterium diffusion through the surface barrier). A necessary high diffusion mobility of deuterium is provided by the amorphous state of Mg83+xVx samples. The deuterium desorption data obtained on the example of Mg-V and Mg-Zr composites provide support for further research into hydrogen storage materials containing low-soluble chemical elements in the alloy components.

  2. Displacement desorption test of coalbed methane and its mechanism exploring

    Institute of Scientific and Technical Information of China (English)

    ZHANG Suian; HUO Yongzhong; YE Jianping; TANG Shuheng; MA Dongmin

    2005-01-01

    Through the test of CH4 displaced by CO2 using the coal sample as the adsorbent, this paper has found the coalbed methane (CBM) displacement desorption phenomenon under the natural conditions and CBM mining conditions. With the help of the adsorption theory of the modern physical chemistry and interfacial chemistry, the CBM competitive adsorption and displacement desorption mechanism are intensively discussed, and a new path for studying the CBM desorption mechanism in the CBM exploitation process is explored.

  3. Substrate-Enhanced Micro Laser Desorption Ionization Mass Spectrometry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerodyne Research, Inc. and the University of Massachusetts at Amherst will collaborate to develop laser desorption ionization (LDI) mass spectrometric analysis of...

  4. Testosterone sorption and desorption: Effects of soil particle size

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yong, E-mail: yqi01@unomaha.edu [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Zhang, Tian C. [Civil Engineering Dept., University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182 (United States); Ren, Yongzheng [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-08-30

    Graphical abstract: - Highlights: • Smaller soil particles have higher sorption and lower desorption rates. • The sorption capacity ranks as clay > silt > sand. • Small particles like clays have less potential for desorption. • Colloids (clays) have high potential to facilitate the transport of hormones in soil–water environments. - Abstract: Soils contain a wide range of particles of different diameters with different mobility during rainfall events. Effects of soil particles on sorption and desorption behaviors of steroid hormones have not been investigated. In this study, wet sieve washing and repeated sedimentation methods were used to fractionate the soils into five ranges. The sorption and desorption properties and related mechanisms of testosterone in batch reactors filled with fractionated soil particles were evaluated. Results of sorption and desorption kinetics indicate that small soil particles have higher sorption and lower desorption rates than that of big ones. Thermodynamic results show the sorption processes are spontaneous and exothermal. The sorption capacity ranks as clay > silt > sand, depending mainly on specific surface area and surface functional groups. The urea control test shows that hydrogen bonding contributes to testosterone sorption onto clay and silt but not on sand. Desorption tests indicate sorption is 36–65% irreversible from clay to sand. Clays have highest desorption hysteresis among these five soil fractions, indicating small particles like clays have less potential for desorption. The results provide indirect evidence on the colloid (clay)-facilitated transport of hormones (micro-pollutants) in soil environments.

  5. CO and N$_2$ desorption energies from water ice

    CERN Document Server

    Fayolle, Edith C; Loomis, Ryan; Bergner, Jennifer; Graninger, Dawn M; Rajappan, Mahesh; Öberg, Karin I

    2015-01-01

    The relative desorption energies of CO and N$_2$ are key to interpretations of observed interstellar CO and N$_2$ abundance patterns, including the well-documented CO and N$_2$H$^+$ anti-correlations in disks, protostars and molecular cloud cores. Based on laboratory experiments on pure CO and N$_2$ ice desorption, the difference between CO and N$_2$ desorption energies is small; the N$_2$-to-CO desorption energy ratio is 0.93$\\pm$0.03. Interstellar ices are not pure, however, and in this study we explore the effect of water ice on the desorption energy ratio of the two molecules. We present temperature programmed desorption experiments of different coverages of $^{13}$CO and $^{15}$N$_2$ on porous and compact amorphous water ices and, for reference, of pure ices. In all experiments, $^{15}$N$_2$ desorption begins a few degrees before the onset of $^{13}$CO desorption. The $^{15}$N$_2$ and $^{13}$CO energy barriers are 770 and 866 K for the pure ices, 1034-1143 K and 1155-1298 K for different sub-monolayer co...

  6. Desorption process of deuterium from zircaloys and their oxides

    Energy Technology Data Exchange (ETDEWEB)

    Nakamichi, Haruo; Kinoshita, Chiken; Hara, Masahiro [Kyushu Univ., Fukuoka (Japan)

    1997-11-01

    It is well known that hydrogen behavior plays an important role on the oxidation process of zircaloys. We have investigated the desorption process of deuterium from three kinds of zircaloys (Zry-2, Zry-4 and high-Fe and Ni-Zry-2) and their oxides using thermal desorption spectrometry (TDS). The purpose of the present paper is to get insight into the effect of alloying elements on the desorption behavior of deuterium from the zircaloys and their oxides. We have also performed in-situ observations through TEM for getting the relation between the desorption process and microstructural evolution. The desorption of D{sub 2} implanted by an ion accelerator occurs in two stages; the first and the second stages appear at around 350 K and around 700 K for the metallic zircaloys, respectively. For their oxide films, on the other hand, the desorption rate of D{sub 2} is much higher than that for the metallic zircaloys. It is found that the desorption rate depends strongly on the kind of zircaloys, especially on the concentration of Fe and Ni. From TEM result, it is found that the first desorption stage for the metallic specimens is correlated to the dissolution of the hydrides. (author)

  7. Integrated field emission array for ion desorption

    Energy Technology Data Exchange (ETDEWEB)

    Resnick, Paul J; Hertz, Kristin L.; Holland, Christopher; Chichester, David

    2016-08-23

    An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

  8. Methane desorption from a coal-bed

    Energy Technology Data Exchange (ETDEWEB)

    A.D. Alexeev; E.P. Feldman; T.A. Vasilenko [National Academy of Sciences of Ukraine, Donetsk (Ukraine). Donetsk Institute for Physics of Mining Processes

    2007-11-15

    We study the desorption of methane from a coal-bed. A model taking into account both methane diffusion in coal-blocks and its filtration through the system of open pores and cracks is developed. Methane pressure in the coal-bed is found for an arbitrary instant of time. Dependency of the rate of methane release upon the block size, open and closed porosity, viscosity, solubility, bed pressure and temperature is established. We derive the effective coefficient of diffusion of methane in blocks containing closed pores filled with gaseous methane. It is shown that at a hindered diffusion methane is distinctly divided into the 'quick' and the 'slow' one. 25 refs., 5 figs.

  9. Integrated field emission array for ion desorption

    Energy Technology Data Exchange (ETDEWEB)

    Resnick, Paul J; Hertz, Kristin L; Holland, Christopher; Chichester, David; Schwoebel, Paul

    2013-09-17

    An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

  10. Integrated field emission array for ion desorption

    Science.gov (United States)

    Resnick, Paul J; Hertz, Kristin L; Holland, Christopher; Chichester, David; Schwoebel, Paul

    2013-09-17

    An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

  11. Copper desorption from Gelidium algal biomass.

    Science.gov (United States)

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2007-04-01

    Desorption of divalent copper from marine algae Gelidium sesquipedale, an algal waste (from agar extraction industry) and a composite material (the algal waste immobilized in polyacrylonitrile) was studied in a batch system. Copper ions were first adsorbed until saturation and then desorbed by HNO(3) and Na(2)EDTA solutions. Elution efficiency using HNO(3) increases as pH decreases. At pH=1, for a solid to liquid ratio S/L=4gl(-1), elution efficiency was 97%, 95% and 88%, the stoichiometric coefficient for the ionic exchange, 0.70+/-0.02, 0.73+/-0.05 and 0.76+/-0.06 and the selectivity coefficient, 0.93+/-0.07, 1.0+/-0.3 and 1.1+/-0.3, respectively, for algae Gelidium, algal waste and composite material. Complexation of copper ions by EDTA occurs in a molar proportion of 1:1 and the elution efficiency increases with EDTA concentration. For concentrations of 1.4, 0.88 and 0.57 mmoll(-1), the elution efficiency for S/L=4gl(-1), was 91%, 86% and 78%, respectively, for algae Gelidium, algal waste and composite material. The S/L ratio, in the range 1-20gl(-1), has little influence on copper recovery by using 0.1M HNO(3). Desorption kinetics was very fast for all biosorbents. Kinetic data using HNO(3) as eluant were well described by the mass transfer model, considering the average metal concentration in the solid phase and the equilibrium relationship given by the mass action law. The homogeneous diffusion coefficient varied between 1.0 x 10(-7)cm(2)s(-1) for algae Gelidium and 3.0 x 10(-7)cm(2)s(-1) for the composite material.

  12. Laser desorption of NO from a thick C 60 film

    Science.gov (United States)

    Hoger, T.; Marzok, C.; Jongma, R. T.; Zacharias, H.

    2006-09-01

    The desorption of NO molecules from a thick C 60 film is reported. A thermal desorption spectrum indicates two adsorption sites with binding energies of Eb = 0.30 eV and 0.55 eV. For laser desorption the fullerene surface is exposed to NO and excited by 7 ns UV laser pulses. Desorbing NO molecules are recorded state selectively as well as time resolved. The time-of-flight measurement indicates three different desorption pathways. A fast channel shows rovibronic temperatures of Trot( v″ = 0) = 370 K, Trot( v″ = 1) = 390 K and Tvib = 610 K as well as strong rotational-translational coupling. The desorption yield for the fast channel increases linearly with pulse energy with a desorption cross section of σ = (5.1 ± 0.9) × 10 -17 cm 2. Dominating the signal for small J″ values is a slow channel with low rotational and translational temperatures of about 110 K. We assign this peak to a laser-induced thermal desorption. For large pump-probe delays the data deviate from the Maxwellian flux distribution and a third channel appears with extremely late arrival times.

  13. Adsorption-Desorption Characteristics of Chlorimuron-Ethyl in Soils

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The adsorption-desorption characteristics of chlorimuron-ethyl in soils were investigated to provide the basic data for evaluating the safety in field and the risk to water resource. The adsorption-desorption experiment was conducted by the batch equilibration and HPLC techniques; furthermore, data were analyzed with 5 mathematic models to describe the characteristics and mechanism of adsorption-desorption and translocation of the herbicide in soils. The results showed that the adsorption-desorption isotherms of chlorimuron-ethyl fitted for the Freundlich model well, and the physical reaction presents the main contribution during the adsorption-desorption process. The adsorption values (Kads-f) of chlorimuron-ethyl in 8 types of soil ranged from 0.798 to 6.891. The isotherms of 2# (Jiangxi clay) and 3# (Jiangxi sand loam)soils belong to the S-type curve, while the isotherms of another 6 type soils belong to the L-type isotherm. The results of desorption indicated that the hysteresis phenomena appeared during the desorption process, and the hysteresis coefficients(H) of the herbicides in 8 soils varied from 0.259-0.980. Furthermore, Kads-f and desorption values (Kdes-f) increased with the OM (%) and the clay content increasing, while the values decreased with the soils pH increasing. The H values decreased with the OM and the clay content increasing, and increased with the soils pH increasing. It can be concluded that the low adsorption abilities of chlorimuron-ethyl in test soils and un-reversible adsorption existed in the process, which will induce the great translocation of the herbicide after application in field. It can be transported to ground or groundwater causing risk to environments. The physical and chemical properties of soils, including the OM, the clay content, and the pH of soil were the dominating factors during the adsorption-desorption.

  14. Temperature programmed desorption of weakly bound adsorbates on Au(111)

    Science.gov (United States)

    Engelhart, Daniel P.; Wagner, Roman J. V.; Meling, Artur; Wodtke, Alec M.; Schäfer, Tim

    2016-08-01

    We have performed temperature programmed desorption (TPD) experiments to analyze the desorption kinetics of Ar, Kr, Xe, C2H2, SF6, N2, NO and CO on Au(111). We report desorption activation energies (Edes), which are an excellent proxy for the binding energies. The derived binding energies scale with the polarizability of the molecules, consistent with the conclusion that the surface-adsorbate bonds arise due to dispersion forces. The reported results serve as a benchmark for theories of dispersion force interactions of molecules at metal surfaces.

  15. Hydrogen Desorption from Mg Hydride: An Ab Initio Study

    Directory of Open Access Journals (Sweden)

    Simone Giusepponi

    2012-07-01

    Full Text Available Hydrogen desorption from hydride matrix is still an open field of research. By means of accurate first-principle molecular dynamics (MD simulations an Mg–MgH2 interface is selected, studied and characterized. Electronic structure calculations are used to determine the equilibrium properties and the behavior of the surfaces in terms of structural deformations and total energy considerations. Furthermore, extensive ab-initio molecular dynamics simulations are performed at several temperatures to characterize the desorption process at the interface. The numerical model successfully reproduces the experimental desorption temperature for the hydride.

  16. Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Masashi, E-mail: Masashi.Shimada@inl.gov [Fusion Safety Program, Idaho National Laboratory, Idaho Falls, ID (United States); Hara, Masanori [Hydrogen Isotope Research Center, University of Toyama, Toyama (Japan); Otsuka, Teppei [Kyushu University, Interdisciplinary Graduate School of Engineering Science, Higashi-ku, Fukuoka (Japan); Oya, Yasuhisa [Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Shizuoka (Japan); Hatano, Yuji [Hydrogen Isotope Research Center, University of Toyama, Toyama (Japan)

    2015-08-15

    Three tungsten samples irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to deuterium plasma (ion fluence of 1 × 10{sup 26} m{sup −2}) at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy was performed with a ramp rate of 10 °C min{sup −1} up to 900 °C, and the samples were annealed at 900 °C for 0.5 h. These procedures were repeated three times to uncover defect-annealing effects on deuterium retention. The results show that deuterium retention decreases approximately 70% for at 500 °C after each annealing, and radiation damages were not annealed out completely even after the 3rd annealing. TMAP modeling revealed the trap concentration decreases approximately 80% after each annealing at 900 °C for 0.5 h.

  17. Desorption kinetics of benzene in a sandy soil in the presence of powdered activated carbon.

    Science.gov (United States)

    Choi, J-W; Kim, S-B; Kim, D-J

    2007-02-01

    Desorption kinetics of benzene was investigated with a modified biphasic desorption model in a sandy soil with five different powdered activated carbon (PAC) contents (0, 1, 2, 5, 10% w/w) as sorbents. Sorption experiments followed by series dilution desorption were conducted for each sorbent. Desorption of benzene was successively performed at two stages using deionized water and hexane. Modeling was performed on both desorption isotherm and desorption rate for water-induced desorption to elucidate the presence of sorption-desorption hysteresis and biphasic desorption and if present to quantify the desorption-resistant fraction (q (irr)) and labile fraction (F) of desorption site responsible for rapid process. Desorption isotherms revealed that sorption-desorption exhibited a severe hysteresis with a significant fraction of benzene being irreversibly adsorbed onto both pure sand and PAC, and that desorption-resistant fraction (q (irr)) increased with PAC content. Desorption kinetic modeling showed that desorption of benzene was biphasic with much higher (4-40 times) rate constant for rapid process (k (1)) than that for slow process (k (2)), and that the difference in the rate constant increased with PAC content. The labile fraction (F) of desorption site showed a decreasing tendency with PAC. The experimental results would provide valuable information on remediation methods for soils and groundwater contaminated with BTEX.

  18. Salt Tolerance of Desorption Electrospray Ionization (DESI)

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Ayanna U. [Purdue University; Talaty, Nari [Purdue University; Cooks, R G [Purdue University; Van Berkel, Gary J [ORNL

    2007-01-01

    Suppression of ion intensity in the presence of high salt matrices is common in most mass spectrometry ionization techniques. Desorption electrospray ionization (DESI) is an ionization method that exhibits salt tolerance, and this is investigated. DESI analysis was performed on three different drug mixtures in the presence of 0, 0.2, 2, 5, 10, and 20% NaCl:KCl weight by volume from seven different surfaces. At physiological concentrations individual drugs in each mixture were observed with each surface. Collision-induced dissociation (CID) was used to provide additional confirmation for select compounds. Multiple stage experiments, to MS5, were performed for select compounds. Even in the absence of added salt, the benzodiazepine containing mixture yielded sodium and potassium adducts of carbamazepine which masked the ions of interest. These adducts were eliminated by adding 0.1% 7M ammonium acetate to the standard methanol:water (1:1) spray solvent. Comparison of the salt tolerance of DESI with that of electrospray ionization (ESI) demonstrated much better signal/noise characteristics for DESI in this study. The salt tolerance of DESI was also studied by performing limit of detection and dynamic range experiments. Even at a salt concentration significantly above physiological concentrations, select surfaces were effective in providing spectra that allowed the ready identification of the compounds of interest. The already high salt tolerance of DESI can be optimized further by appropriate choices of surface and spray solution.

  19. Adsorption and desorption kinetics of carbofuran in acid soils.

    Science.gov (United States)

    Bermúdez-Couso, Alipio; Fernández-Calviño, David; Pateiro-Moure, Miriam; Nóvoa-Muñoz, Juan Carlos; Simal-Gándara, Jesús; Arias-Estévez, Manuel

    2011-06-15

    Carbofuran adsorption and desorption were investigated in batch and stirred flow chamber (SFC) tests. The carbofuran adsorption capacity of the soils was found to be low and strongly dependent on their clay and organic carbon contents. Carbofuran sorption was due mainly (>80%) to fast adsorption processes governed by intraparticle diffusion. The adsorption kinetic constant for the pesticide ranged from 0.047 to 0.195 min(-1) and was highly correlated with constant n in the Freundlich equation (r=0.965, Pcarbofuran desorption to be highly variable and negatively correlated with eCEC and the clay content. The SFC tests showed that soil organic carbon (C) plays a key role in the irreversibility of carbofuran adsorption. Carbofuran desorption increased rapidly at C contents below 4%. The desorption kinetic constant for the compound (0.086-0.195 min(-1)) was generally higher than its adsorption kinetic constant; therefore, carbofuran is more rapidly desorbed than it is adsorbed in soil.

  20. ACTIVATION ENERGY OF DESORPTION OF DIBENZOFURAN ON ACTIVATED CARBONS

    Institute of Scientific and Technical Information of China (English)

    LI Xiang; LI Zhong; XI Hongxia; LUO Lingai

    2004-01-01

    Three kinds of commercial activated carbons, such as Norit RB1, Monolith and Chemviron activated carbons, were used as adsorbents for adsorption of dibenzofuran. The average pore size and specific surface area of these activated carbons were measured. Temperature Programmed Desorption (TPD) experiments were conducted to measure the TPD curves of dibenzofuran on the activated carbons, and then the activation energy for desorption of dibenzofuran on the activated carbons was estimated. The results showed that the Chemviron and the Norit RB1 activated carbon maintained higher specific surface area and larger micropore pore volume in comparison with the Monolith activated carbon, and the activation energy for the desorption of dibenzofuran on these two activated carbons was higher than that on the Monolith activated carbon. The smaller the pore of the activated carbon was, the higher the activated energy of dibenzofuran desorption was.

  1. Sorption, Desorption and Diffusion of Tc Under Anaerobic Conditions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The sorption and diffusion of Tc on granite under anaerobic conditions were investigated. Influencesof pH values, ferrous minerals(reduced iron powder or magnetite), bentonite, concentration of cations andanion (Fe3+, Fe2+ and CO32-) on the distribution coefficient, Kd, were studied. The sorption mechanism of99Tc on granite was analyzed by the desorption method of adding H2O2 into desorption solvent. Based on

  2. Sorption and desorption of 1,4-dichlorobenzene on peat

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Sorption and desorption of 1,4-dichlorobenzene (DCB) on peat (>92% organic matter)display large-scale hysteresis and nonlinearity. The magnitude of desorption hysteresis decreases in the order: untreated Pahokee peat (P)>acid treated peat (FP)>humin (TP). The desorption percentages are lower than 28% of the sorbed 1, 4-DCB after desorbing for 6 days. The sorption and desorption isotherms are well fitted to Freundlich equation, whose parameter 1/n ranges from 0.055 to 0.527. Moreover, the parameter 1/n of the desorption isotherm is significantly lower than that of the sorption isotherm, but the parameter IogK increases on contrary to 1/n. The desorption isotherms are very well fitted to Langmuir equation, whose Qm decreases in the order: TP>FP>P.The apparent partition coefficients (Kp) increase with increasing sorption time or decreasing aqueous equilibrium concentration of DCB. And Kp of P is significantly higher than that of FP or TP.

  3. Laser-induced thermal desorption of aniline from silica surfaces

    Science.gov (United States)

    Voumard, Pierre; Zenobi, Renato

    1995-10-01

    A complete study on the energy partitioning upon laser-induced thermal desorption of aniline from silica surfaces was undertaken. The measurements include characterization of the aniline-quartz adsorption system using temperature-programmed desorption, the extrapolation of quasiequilibrium desorption temperatures to the regime of laser heating rates on the order of 109-1010 K/s by computational means, measurement of the kinetic energy distributions of desorbing aniline using a pump-probe method, and the determination of internal energies with resonance-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resulting desorption rates, based on a finite-difference mathematical description of pulsed laser heating. While the surface temperature of laser-heated silica reaches about 600-700 K at the time of desorption, the translational temperature of laser-desorbed aniline was measured to be Tkin=420±60 K, Tvib was 360±60 K, and Trot was 350±100 K. These results are discussed using different models for laser-induced thermal desorption from surfaces.

  4. Calcium lignosulfonate adsorption and desorption on Berea sandstone.

    Science.gov (United States)

    Grigg, Reid B; Bai, Baojun

    2004-11-01

    This paper describes adsorption and desorption studies carried out with calcium lignosulfonate (CLS) on Berea sandstone. Circulation experiments were performed to determine CLS adsorption isotherms and the effects of CLS concentration, temperature, salinity, brine hardness, and injection rate on adsorption density. Flow-through experiments were performed to assess the reversibility of CLS adsorption and the influence of postflush rate, brine concentration, brine hardness, brine pH, and temperature on the desorption process. Results indicate that CLS adsorption isotherms on Berea sandstone follow the Freundlich isotherm law. The results presented in this paper on the effects of CLS adsorption and desorption on Berea sandstone show that: (1) increasing CLS concentration and salinity increases CLS adsorption density; (2) increasing temperature will decrease adsorption density; (3) increasing injection rate of CLS solution will slightly decrease CLS adsorption density; (4) postflush rate and salinity of brine have a large impact on the CLS desorption process; (5) the adsorption and desorption process are not completely reversible; and (5) temperature and pH of the postflush brine have little effect on desorption.

  5. Plasma Using a Simulated Gas Mixture: A Case Study on the Effect of Corona Electrodes

    Institute of Scientific and Technical Information of China (English)

    K. YOSHIDA; B. S. RAJANIKANTH; M. OKUBO

    2009-01-01

    In this study, reduction and desorption of oxides of nitrogen (NOx) were conducted using an electrical discharge plasma technique. The study was carried out using a simulated gas mixture to explore the possibility of re-generation of used adsorbents by a nonthermal plasma desorption technique. Three different types of corona electrodes, namely, pipe, helical wire, and straight wire, were used for analyzing their effectiveness in NOx reduction/desorption. The pipe-type corona electrode exhibited a nitric oxide (NO) conversion of 50%, which is 1.5 times that of the straight-wire-type electrode at an energy density of 175 J/L. The helical-wire-type corona electrode exhibited a NOx desorption efficiency almost 4 times that of the pipe-type electrode, indicating the possibility that corona-generated species play a crucial role in desorption.

  6. Adsorption and desorption dynamics of citric acid anions in soil

    KAUST Repository

    Oburger, E.

    2011-07-26

    The functional role of organic acid anions in soil has been intensively investigated, with special focus on (i) microbial respiration and soil carbon dynamics, (ii) nutrient solubilization or (iii) metal detoxification and reduction of plant metal uptake. Little is known about the interaction dynamics of organic acid anions with the soil matrix and the potential impact of adsorption and desorption processes on the functional significance of these effects. The aim of this study was to characterize experimentally the adsorption and desorption dynamics of organic acid anions in five agricultural soils differing in iron and aluminium oxide contents and using citrate as a model carboxylate. Results showed that both adsorption and desorption processes were fast in all soils, reaching a steady state within approximately 1 hour. However, for a given total soil citrate concentration (ct) the steady state was critically dependent on the starting conditions of the experiment, whether most of the citrate was initially present in solution (cl) or held on the solid phase (cs). Specifically, desorption-led processes resulted in significantly smaller steady-state solution concentrations than adsorption-led processes, indicating that hysteresis occurred. As it is not possible to distinguish between different adsorption and desorption pools in soil experimentally, a new dynamic hysteresis model that relies only on measured soil solution concentrations was developed. The model satisfactorily explained experimental data and was able to predict dynamic adsorption and desorption behaviour. To demonstrate its use, we applied the model to two relevant situations involving exudation and microbial degradation. The study highlighted the complex nature of citrate adsorption and desorption dynamics in soil. We conclude that existing models need to incorporate both temporal and hysteresis components to describe realistically the role and fate of organic acids in soil processes. © 2011 The

  7. The laser desorption/laser ionization mass spectra of some methylated xanthines and the laser desorption of caffeine and theophylline from thin layer chromatography plates

    Science.gov (United States)

    Rogers, Kevin; Milnes, John; Gormally, John

    1993-02-01

    Laser desorption/laser ionization time-of-flight mass spectra of caffeine, theophylline, theobromine and xanthine are reported. These mass spectra are compared with published spectra obtained using electron impact ionization. Mass spectra of caffeine and theophylline obtained by IR laser desorption from thin layer chromatography plates are also described. The laser desorption of materials from thin layer chromatography plates is discussed.

  8. Sorption-desorption behavior of polybrominated diphenyl ethers in soils

    Energy Technology Data Exchange (ETDEWEB)

    Olshansky, Yaniv; Polubesova, Tamara [Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel); Vetter, Walter [Institute of Food Chemistry (170b), University of Hohenheim, Garbenstr. 28, D-70599 Stuttgart (Germany); Chefetz, Benny, E-mail: chefetz@agri.huji.ac.il [Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel)

    2011-10-15

    Polybrominated diphenyl ethers (PBDEs) are flame retardants that are commonly found in commercial and household products. These compounds are considered persistent organic pollutants. In this study, we used 4,4'-dibromodiphenyl ether (BDE-15) as a model compound to elucidate the sorption and desorption behavior of PBDEs in soils. The organic carbon-normalized sorption coefficient (K{sub OC}) of BDE-15 was more than three times higher for humin than for bulk soils. However, pronounced desorption hysteresis was obtained mainly for bulk soils. For humin, increasing concentration of sorbed BDE-15 resulted in decreased desorption. Our data illustrate that BDE-15 and probably other PBDEs exhibit high sorption affinity to soils. Moreover, sorption is irreversible and thus PBDEs can potentially accumulate in the topsoil layer. We also suggest that although humin is probably a major sorbent for PBDEs in soils, other humic materials are also responsible for their sequestration. - Highlights: > BDE-15 exhibited pronounced desorption hysteresis. > BDE-15 sowed higher sorption affinity to humin as compared to the bulk soils. > Sequestration of PBDEs depends on soil organic matter constitutes other than humin. - Pronounced desorption hysteresis was observed for BDE-15 in natural soils.

  9. The study of 'microsurfaces' using thermal desorption spectroscopy

    Science.gov (United States)

    Thomas, M. E.; Poppa, H.; Pound, G. M.

    1979-01-01

    The use of a newly combined ultrahigh vacuum technique for studying continuous and particulate evaporated thin films using thermal desorption spectroscopy (TDS), transmission electron microscopy (TEM), and transmission electron diffraction (TED) is discussed. It is shown that (1) CO thermal desorption energies of epitaxially deposited (111) Ni and (111) Pd surfaces agree perfectly with previously published data on bulk (111) single crystal, (2) contamination and surface structural differences can be detected using TDS as a surface probe and TEM as a complementary technique, and (3) CO desorption signals from deposited metal coverages of one-thousandth of a monolayer should be detectable. These results indicate that the chemisorption properties of supported 'microsurfaces' of metals can now be investigated with very high sensitivity. The combined use of TDS and TEM-TED experimental methods is a very powerful technique for fundamental studies in basic thin film physics and in catalysis.

  10. Femtosecond laser pulse induced desorption: A molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lončarić, Ivor, E-mail: ivor.loncaric@gmail.com [Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 San Sebastián (Spain); Alducin, Maite [Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 San Sebastián (Spain); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián (Spain); Saalfrank, Peter [Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam (Germany); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián (Spain); Juaristi, J. Iñaki [Departamento de Física de Materiales, Facultad de Químicas, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián (Spain); Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), P. Manuel de Lardizabal 5, 20018 San Sebastián (Spain); Donostia International Physics Center DIPC, P. Manuel de Lardizabal 4, 20018 San Sebastián (Spain)

    2016-09-01

    In recent simulations of femtosecond laser induced desorption of molecular oxygen from the Ag(110) surface, it has been shown that depending on the properties (depth and electronic environment) of the well in which O{sub 2} is adsorbed, the desorption can be either induced dominantly by hot electrons or via excitations of phonons. In this work we explore whether the ratios between the desorption yields from different adsorption wells can be tuned by changing initial surface temperature and laser pulse properties. We show that the initial surface temperature is an important parameter, and that by using low initial surface temperatures the electronically mediated process can be favored. In contrast, laser properties seem to have only a modest influence on the results.

  11. A study of the process of desorption of hexavalent chromium

    Directory of Open Access Journals (Sweden)

    W.B. Amorim

    2003-09-01

    Full Text Available In this work the process of desorption of hexavalent chromium, a toxic metal ion, from the marine algae Sargassum sp, following biosorption experiments 2³ factorial design was studied. A technique was applied to three eluents: HCl, H2SO4 and EDTA. Three factors of importance were evaluated: concentration of eluent, the ratio between mass of biosorbent and volume of eluent (S/L and process time. A statistical analysis of the experimental results showed that the three variables evaluated are significant for all three eluents. The models for chromium desorption were validated, as the results agreed well with the observed values. Through use of the response surface methodology, a factorial design based optimization technique; it was possible to identify the most suitable eluent and the interval of values for the process variables that resulted in the most significant desorption of chromium, which is relevant information for work aiming at process optimization.

  12. Direct scattering, trapping, and desorption in atom-surface collisions.

    Science.gov (United States)

    Fan, Guoqing; Manson, J R

    2008-08-08

    Maxwell is credited as the first to invoke the assumption that an impinging gas beam scatters from a surface with a direct contribution exhibiting little change in state and a trapping-desorption fraction that desorbs in equilibrium [J. C. Maxwell, Phil. Trans. R. Soc. London 170, 231 (1879)]. Here a classical mechanical scattering theory is developed to describe direct scattering, trapping, and subsequent desorption of the incident beam. This theory allows a rigorous test of the Maxwell assumption and determines the conditions under which it is valid. The theory also gives quantitative explanations of important new experimental measurements [K. D. Gibson, N. Isa, and S. J. Sibener, J. Chem. Phys. 119, 13 083 (2003)] for direct and trapping-desorption scattering of Ar atoms by a self-assembled layer of 1-decanethiol on Au(111).

  13. Desorption Dynamics, Internal Energies and Imaging of Organic Molecules from Surfaces with Laser Desorption and Vacuum Ultraviolet (VUV) Photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Kostko, Oleg; Takahashi, Lynelle K.; Ahmed, Musahid

    2011-04-05

    There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser-desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron-based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216-346 K. The observed low translational temperatures, as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer, using laser desorption VUV postionization shows 5 mu m feature details while using a 30 mu m laser spot size and 7 ns duration. Applications of laser desorption postionization to the analysis of cellulose, lignin and humic acids are briefly discussed.

  14. Leaf water absorption and desorption functions for three turfgrasses

    Science.gov (United States)

    Liang, Xi; Su, Derong; Yin, Shuxia; Wang, Zhi

    2009-09-01

    SummaryPlant leaf can absorb water when the leaf is in contact with water. This happens when the rainfall is intercepted by plant leaves, where the intercepted part of rain remains on the leaf surface. When the intercepted water is either absorbed or subsequently evaporated into the atmosphere, the plant leaves can dissipate water through the desorption process until the plant is dry or rewatered. In this paper, two symptomatic models in the form of exponential functions for leaf water absorption and leaf water desorption were derived and validated by experimental data using leaves of three turfgrasses (Tall fescue, Perennial ryegrass and Kentucky bluegrass). Both the models and measured data showed that the rate of leaf water absorption was high at the low initial leaf water content and then gradually leveled off toward the saturated leaf water content. The rate of leaf water desorption was high at the high initial leaf water content then decreased drastically over time toward zero. The different plant leaves showed different exponents and other parameters of the functions which indicate the difference of plant species. Both the absorption and desorption rates were relatively higher for the Kentucky bluegrass and lower for the Tall fescue and Perennial ryegrass. The concept of specific leaf area ( SLA) was used to understand the saturated leaf water content ( C s) of the three turfgrasses. Linear relationships were found between C s and SLA. The leaf water absorption and desorption functions are useful for deriving physiological parameters of the plant such as permanent wilting leaf water content, naturally irreducible leaf water content, exponential leaf water absorption coefficient, and exponential leaf desorption coefficient, as well as for evaluating the effects of rainfall interception on plant growth and water use efficiency.

  15. Heavy-Ion-Induced Electronic Desorption of Gas from Metals

    CERN Document Server

    Molvik, A W; Mahner, E; Kireeff Covo, M; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Krämer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L

    2007-01-01

    During heavy-ion operation in several particle accelerators worldwide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion-induced gas desorption scales with the electronic energy loss (dEe/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  16. Desorption of toluene from modified clays using supercritical carbon dioxide

    Directory of Open Access Journals (Sweden)

    Carneiro D. G. P.

    2004-01-01

    Full Text Available The main objective of this work is to study the regeneration capacity of modified clays using supercritical fluid. These modified clays are used as organic compound adsorvents. The experimental step was done using a packed column with the clay contaminated by toluene. The results obtained showed the influence of the density of the supercritical CO2 and of the organic modifier in the desorption process. These data were modeled with first- and second-order models. Better results were obtained using the second-order model. This study makes possible the scale-up of the desorption process for regeneration of solid matrices using supercritical fluids.

  17. Heavy-ion induced electronic desorption of gas from metals

    Energy Technology Data Exchange (ETDEWEB)

    Molvik, A W; Kollmus, H; Mahner, E; Covo, M K; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Kramer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L

    2006-12-19

    During heavy ion operation in several particle accelerators world-wide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion induced gas desorption scales with the electronic energy loss (dE{sub e}/d/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  18. PAH desorption from river floodplain soils using supercritical fluid extraction.

    Science.gov (United States)

    Yang, Yi; Cajthaml, Tomás; Hofmann, Thilo

    2008-12-01

    Sequential supercritical fluid extraction (SFE) was performed in order to estimate desorption of PAHs from river floodplain soils which contain coal and coal-derived particles. Original soils, soils' light fractions (rhoextractable contaminants ranged from decades for 2-4-ring PAHs and hundreds of years for 5-6-ring PAHs. We demonstrate that, despite high soil PAH concentrations which are due to coal and coal-derived particles, the general environmental risk is reduced by the very slow and extremely slow desorption rates.

  19. Nonthermal current-stimulated desorption of gases from carbon nanotubes.

    Science.gov (United States)

    Salehi-Khojin, Amin; Lin, Kevin Y; Field, Christopher R; Masel, Richard I

    2010-09-10

    The desorption of gases from carbon nanotubes is usually a slow process that limits the nanotubes' utility as sensors or as memristors. Here, we demonstrate that flow in the nanotube above the Poole-Frenkel conduction threshold can stimulate adsorbates to desorb without heating the sensor substantially. The method is general: alcohols, aromatics, amines, and phosphonates were all found to desorb. We postulate that the process is analogous to electron-stimulated desorption, but with an internally conducted rather than externally applied source of electrons.

  20. Hydrogen–deuterium exchange on plasma-exposed W and SS surface

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, Ikuji, E-mail: takagi@nucleng.kyoto-u.ac.jp; Nomura, Shinji; Minamimoto, Toshihiro; Akiyoshi, Masafumi; Kobayashi, Taishi; Sasaki, Takayuki

    2015-08-15

    The desorption cross section for hydrogen isotopes adsorbed on stainless steel (SS) and tungsten (W) has been evaluated experimentally to provide basic information on tritium exchange. One side of a sample sheet was alternately exposed to H and D plasma, and deuterium density on the surface was repeatedly observed using nuclear reaction analysis (NRA) under continuous plasma exposure. From the time dependent change in the deuterium density, the desorption cross sections for SS and W were estimated to be 6.9 ± 2.3 × 10{sup −23} m{sup 2} and 4.6 ± 1.0 × 10{sup −23} m{sup 2}, respectively. No significant differences in the cross section between H and D plasma were observed. Recombinative desorption was found to dominate the desorption process owing to the low incident energy of hydrogen atoms.

  1. Electron Stimulated Desorption of Condensed Gases on Cryogenic Surfaces

    CERN Document Server

    Tratnik, H; Hilleret, Noël

    2005-01-01

    In ultra-high vacuum systems outgassing from vacuum chamber walls and desorption from surface adsorbates are usually the factors which in°uence pressure and residual gas composition. In particular in beam vacuum systems of accelerators like the LHC, where surfaces are exposed to intense synchro- tron radiation and bombardment by energetic ions and electrons, properties like the molecular desorption yield or secondary electron yield can strongly in°uence the performance of the accelerator. In high-energy particle accelerators operating at liquid helium temperature, cold surfaces are exposed to the bombardment of energetic photons, electrons and ions. The gases released by the subsequent desorption are re-condensed on the cold surfaces and can be re-desorbed by the impinging electrons and ions. The equilibrium coverage reached on the surfaces exposed to the impact of energetic particles depends on the desorption yield of the condensed gases and can a®ect the operation of the accelerator by modifying th...

  2. Gold ion beams induced desorption studies for Booster Nuclotron

    Science.gov (United States)

    Kuznetsov, A. B.; Tuzikov, A. V.; Philippov, A. V.

    2016-12-01

    Heavy ions induced pressure rise is one of the machine limits. The calculation results of the gold ion beam 197Au31+ losses due to residual gas interaction in view of desorption of adsorbed particles on the Booster Nuclotron vacuum chamber surface are discussed.

  3. Synthesis and Hydrogen Desorption Properties of Aluminum Hydrides.

    Science.gov (United States)

    Jeong, Wanseop; Lee, Sang-Hwa; Kim, Jaeyong

    2016-03-01

    Aluminum hydride (AlH3 or alane) is known to store maximum 10.1 wt.% of hydrogen at relatively low temperature (hydrogen desorption are still not clear. To understand the desorption properties of hydrogen in alane, thermodynamically stable α-AlH3 was synthesized by employing an ethereal reaction method. The dependence of pathways on phase formation and the properties of hydrogen evolution were investigated, and the results were compared with the ones for γ-AlH3. It was found that γ-AlH3 requires 10 degrees C higher than that of γ-AlH3 to form, and its decomposition rate demonstrated enhanced endothermic stabilities. For desorption, all hydrogen atoms of alane evolved under an isothermal condition at 138 degrees C in less than 1 hour, and the sample completely transformed to pure aluminum. Our results show that the total amount of desorbed hydrogen from α-AlH3 exceeded 9.05 wt.%, with a possibility of further increase. Easy synthesis, thermal stability, and a large amount of hydrogen desorption of alane fulfill the requirements for light-weight hydrogen storage materials once the pathway of hydrogen cycling is provided.

  4. Organic contaminants in soil, desorption kinetics and microbial degradation

    NARCIS (Netherlands)

    Schlebaum, W.

    1999-01-01

    The availability of organic contaminants in soils or sediments for microbial degradation or removal by physical means (e.g.) soil washing or soil venting) depends on the desorption kinetics of these contaminants from the soil matrix. When the organic contaminants desorb very slow from the soil matri

  5. Linking desorption kinetics to phenanthrene biodegradation in soil

    Energy Technology Data Exchange (ETDEWEB)

    Rhodes, Angela H.; McAllister, Laura E. [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Semple, Kirk T., E-mail: k.semple@lancaster.ac.u [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2010-05-15

    The desorption of polycyclic aromatic hydrocarbons (PAHs) often exhibits a biphasic profile similar to that observed for biodegradation whereby an initial rapid phase of degradation or desorption is followed by a phase of much slower transformation or release. Most investigations to-date have utilised a polymeric sorbent, such as Tenax, to characterise desorption, which is methodologically unsuitable for the analysis of soil. In this study, desorption kinetics of {sup 14}C-phenanthrene were measured by consecutive extraction using aqueous solutions of hydroxypropyl-beta-cyclodextrin (HPCD). The data indicate that the fraction extracted after 24 h generally approximated the linearly sorbed, rapidly desorbing fraction (F{sub rap}), calculated using a three-compartment model. A good linear correlation between phenanthrene mineralised and F{sub rap} was observed (r{sup 2} = 0.89; gradient = 0.85; intercept = 8.20). Hence HPCD extraction (24 h) and first-order three-compartment modelling appear to provide an operationally straightforward tool for estimating mass-transfer limited biodegradation in soil. - Aqueous hydroxypropyl-beta-cyclodextrin (HPCD) solutions can predict the rapidly desorbing and microbially degradable fractions of phenanthrene in soils.

  6. Development of the positron-induced ion-desorption apparatus

    CERN Document Server

    Kanazawa, I

    2002-01-01

    The principle of the positron-induced ion-desorption, which is developed recently, and experimental apparatus are explained and study of desorption of positron-induced hydrogen ion from surface of Ni is reported as an example. The slow positron beam system in the positron-induced ion-desorption spectroscopy is consisted of two stages, moderator and transformation from magnetic transport type to electrostatic transport type. Positron is antiparticle of electron and localized both outside and monolayer of surface, which is special futures and used to analyze the surface. The number of emission positive charge particles from the clean Ni surface was changed by coil current at 1.9 keV and 2.9 keV incident positron energy. The number of re-emission positron at 1.9 keV was larger than at 2.9 keV. The number of emission positive charge particles from the clean Ni surface adsorbed monolayer hydrogen atom were decreased with coil current at 1.9 keV and 2.9 keV. The number of desorption hydrogen particle at 1.9 keV was...

  7. Permeability changes in coal resulting from gas desorption

    Energy Technology Data Exchange (ETDEWEB)

    Levine, J.R.; Johnson, P.M.

    1992-01-01

    Research continued on the study of coal permeability and gas desorption. This quarter, most of the effort involved identifying problems with the microbalance and then getting it repaired. Measurement of the amount of gas adsorbed with the microbalance involved corrections for the buoyancy change with pressure and several experiments with helium were made to determine this correction.

  8. Sorption and desorption of arsenate and arsenite on calcite

    DEFF Research Database (Denmark)

    Sø, Helle Ugilt; Postma, Diederik Jan; Jakobsen, Rasmus

    2008-01-01

    The adsorption and desorption of arsenate (As(V)) and arsenite (As(111)) oil calcite was investigated in a series of batch experiments in calcite-equilibrated solutions. The solutions covered a broad range of pH, alkalinity, calcium concentration and ionic strength. The initial arsenic...

  9. Analytical theory of finite-size effects in mechanical desorption

    NARCIS (Netherlands)

    Skvortsov, A.M.; Klushin, L.I.; Fleer, G.J.; Leermakers, F.A.M.

    2010-01-01

    We discuss a unique system that allows exact analytical investigation of first- and second-order transitions with finite-size effects: mechanical desorption of an ideal lattice polymer chain grafted with one end to a solid substrate with a pulling force applied to the other end. We exploit the analo

  10. Influence of surface coverage on the chemical desorption process

    CERN Document Server

    Marco, Minissale

    2014-01-01

    In cold astrophysical environments, some molecules are observed in the gas phase whereas they should have been depleted, frozen on dust grains. In order to solve this problem, astrochemists have proposed that a fraction of molecules synthesized on the surface of dust grains could desorb just after their formation. Recently the chemical desorption process has been demonstrated experimentally, but the key parameters at play have not yet been fully understood. In this article we propose a new procedure to analyze the ratio of di-oxygen and ozone synthesized after O atoms adsorption on oxidized graphite. We demonstrate that the chemical desorption efficiency of the two reaction paths (O+O and O+O$_2$) is different by one order of magnitude. We show the importance of the surface coverage: for the O+O reaction, the chemical desorption efficiency is close to 80 $\\%$ at zero coverage and tends to zero at one monolayer coverage. The coverage dependence of O+O chemical desorption is proved by varying the amount of pre-...

  11. Desorption of plutonium from montmorillonite: An experimental and modeling study

    Science.gov (United States)

    Begg, James D.; Zavarin, Mavrik; Kersting, Annie B.

    2017-01-01

    Desorption of plutonium (Pu) will likely control the extent to which it is transported by mineral colloids. We evaluated the adsorption/desorption behavior of Pu on SWy-1 montmorillonite colloids at pH 4, pH 6, and pH 8 using batch adsorption and flow cell desorption experiments. After 21 days adsorption, Pu(IV) affinity for montmorillonite displayed a pH dependency, with Kd values highest at pH 4 and lowest at pH 8. The pH 8 experiment was further allowed to equilibrate for 6 months and showed an increase in Kd, indicating that true sorption equilibrium was not achieved within the first 21 days. For the desorption experiments, aliquots of the sorption suspensions were placed in a flow cell, and Pu-free solutions were then pumped through the cell for a period of 12 days. Changes in influent solution flow rate were used to investigate the kinetics of Pu desorption and demonstrated that it was rate-limited over the experimental timescales. At the end of the 12-day flow cell experiments, the extent of desorption was again pH dependent, with pH 8 > pH 6 > pH 4. Further, at pH 8, less Pu was desorbed after an adsorption contact time of 6 months than after a contact time of 21 days, consistent with an aging of Pu on the clay surface. A conceptual model for Pu adsorption/desorption that incorporated known surface-mediated Pu redox reactions was used to fit the experimental data. The resulting rate constants indicated processes occurring on timescales of months and even years which may, in part, explain observations of clay colloid-facilitated Pu transport on decadal timescales. Importantly, however, our results also imply that migration of Pu adsorbed to montmorillonite colloids at long (50-100 year) timescales under oxic conditions may not be possible without considering additional phenomena, such as co-precipitation.

  12. The effects of the biogeochemical properties of clay minerals on the Pb sorption and desorption in various redox condition

    Science.gov (United States)

    Koo, T. H.; Kim, J. Y.; Kim, J. W.

    2016-12-01

    The fate and transportation of hazardous trace metal in soil environment can be controlled by various factors including temperature, geological location, properties of bed rock or sediment, human behavior, and biogeochemical reactions. The sorption and desorption process is one of the major process for control the transportation of trace metal in soil-water system. Nonetheless, few studies were focused on the biological controlling parameters, particularly redox reaction of structural metal of clay minerals. Thus, the objective of the present study is to investigate the correlation between the sorption and desorption reaction of Pb and biogeochemical properties of clay minerals. The effects of redox state of structural Fe and layer charge of the minerals on the migration/speciation of Pb at the various geochemical environment will be elucidated. The Fe-rich smectite, nontronite (NAu-1), and bulk soil samples which were collected from abandoned mine areas were reduced by microbial respiration by Shewanella Oneidensis MR-1 and/or Na-dithionite to various oxidation state of structural Fe. Then the Pb-stock solution made with common lead and nitric acid were spiked into the mineral/soil slurry with various Pb concentration to test the sorption and desorption reaction upto 7 days. The reaction was stopped at each time point by freezing the pellet and supernatant separately after centrifugation. Then the concentration and stable isotope ratio of Pb in the supernatant were measured using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Multicollector (MC)-ICP-MS. The structural as well as chemical modification on nontronite and bulk soil sample were measured using x-ray diffraction (XRD), scanning electron microscopy (SEM) and wet chemistry analysis. The changes in Pb species in supernatant by sorption and desorption and its consequences on the clay structural/biogeochemical properties will be discussed.

  13. Investigations into ultraviolet matrix-assisted laser desorption

    Energy Technology Data Exchange (ETDEWEB)

    Heise, Theodore W. [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    Matrix-assisted laser desorption (MALD) is a technique for converting large biomolecules into gas phase ions. Some characteristics of the commonly used uv matrices are determined. Solubilities in methanol range from 0.1 to 0.5 M. Solid phase absorption spectra are found to be similar to solution, but slightly red-shifted. Acoustic and quartz crystal microbalance signals are investigated as possible means of uv-MALD quantitation. Evidence for the existence of desorption thresholds is presented. Threshold values are determined to be in the range of 2 to 3 MW/cm2. A transient imaging technique based on laser-excited fluorescence for monitoring MALD plumes is described. Sensitivity is well within the levels required for studying matrix-assisted laser desorption, where analyte concentrations are significantly lower than those in conventional laser desorption. Results showing the effect of film morphology, particularly film thickness, on plume dynamics are presented. In particular, MALD plumes from thicker films tend to exhibit higher axial velocities. Fluorescent labeling of protein and of DNA is used to allow imaging of their uv-MALD generated plumes. Integrated concentrations are available with respect to time, making it possible to assess the rate of fragmentation. The spatial and temporal distributions are important for the design of secondary ionization schemes to enhance ion yields and for the optimization of ion collection in time-of-flight MS instruments to maximize resolution. Such information could also provide insight into whether ionization is closely associated with the desorption step or whether it is a result of subsequent collisions with the matrix gas (e.g., proton transfer). Although the present study involves plumes in a normal atmosphere, adaptation to measurements in vacuum (e.g., inside a mass spectrometer) should be straightforward.

  14. Sorption and desorption of carbamazepine from water by smectite clays.

    Science.gov (United States)

    Zhang, Weihao; Ding, Yunjie; Boyd, Stephen A; Teppen, Brian J; Li, Hui

    2010-11-01

    Carbamazepine is a prescription anticonvulsant and mood stabilizing pharmaceutical administered to humans. Carbamazepine is persistent in the environment and frequently detected in water systems. In this study, sorption and desorption of carbamazepine from water was measured for smectite clays with the surface negative charges compensated with K+, Ca2+, NH4+, tetramethylammonium (TMA), trimethylphenylammonium (TMPA) and hexadecyltrimethylammonium (HDTMA) cations. The magnitude of sorption followed the order: TMPA-smectite≥HDTMA-smectite>NH4-smectite>K-smectite>Ca-smectite⩾TMA-smectite. The greatest sorption of carbamazepine by TMPA-smectite is attributed to the interaction of conjugate aromatic moiety in carbamazepine with the phenyl ring in TMPA through π-π interaction. Partitioning process is the primary mechanism for carbamazepine uptake by HDTMA-smectite. For NH4-smectite the urea moiety in carbamazepine interacts with exchanged cation NH4+ by H-bonding hence demonstrating relatively higher adsorption. Sorption by K-, Ca- and TMA-smectites from water occurs on aluminosilicate mineral surfaces. These results implicate that carbamazepine sorption by soils occurs primarily in soil organic matter, and soil mineral fractions play a secondary role. Desorption of carbamazepine from the sorbents manifested an apparent hysteresis. Increasing irreversibility of desorption vs. sorption was observed for K-, Ca-, TMA-, TMPA- and HDTMA-clays as aqueous carbamazepine concentrations increased. Desorption hysteresis of carbamazepine from K-, Ca-, NH4-smectites was greater than that from TMPA- and HDTMA-clays, suggesting that the sequestrated carbamazepine molecules in smectite interlayers are more resistant to desorption compared to those sorbed by organic phases in smectite clays.

  15. Adsorption/desorption of phenanthrene on contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Saada, A.; Gaboriau, H.; Amalric, L.; Crouzet, C. [BRGM, Orleans (France)

    2003-07-01

    Polycyclic Aromatic Hydrocarbons (PAH) are persistent environmental contaminants whose behaviour has been thoroughly studies because of their genotoxicity. One of the main processes governing PAH evolution is adsorption onto soil matrices due to the marked hydrophobic properties of this group of pollutants. In this study, pehnanthrene adsorption and desorption were measured for: - an untreated polluted soil (S) from a former coking plant - the same soil washed with toluene in a soxhlet extractor (S{sub w}), which enables the pollutants (PAH and tar) to be extracted from the soil - the fine fraction (<50 {mu}m) of the washed soil (S{sub f}), - a mineral (kaolinite) representative of the polluted soil (K), - the mineral coated with the tar extracted from the polluted soil (K-T). Isotherms of phenanthrene adsorption/desorption on K, K-T and S shows that the hysteresis between the adsorption and desorption isotherms increases 1) with the organic matter content, and 2) for the untreated soil S containing endogenic bacteria, in addition to organic matter. This indicates that tar-type organic matter is capable of reducing the release of phenanthrene by forming bonded residue. For the untreated soil S, endogenic bacteria consume phenanthrene as it is desorbed. Consequently, the desorption isotherm for S is almost horizontal, as if no desorption had taken place. This study has demonstrated the effect that the type of organic matter has on PAH fate, and thus the need to take this into account, particularly where tar is concerned, when assessing the adsorption capacity of soils. (orig.)

  16. Feasibility of the direct coupling of solid-phase extraction-pipette tips with a programmed-temperature vaporiser for gas chromatographic analysis of drugs in plasma

    NARCIS (Netherlands)

    van Hout, M.W J; van Egmond, W.M A; Franke, J.P.; de Zeeuw, R.A; de Jong, G.J.

    2002-01-01

    Solid-phase extraction-pipette tips (SPE-PTs) were used for micro solid-phase extraction of lidocaine and diazepam from plasma. Off-line extraction was followed by on-line desorption. On-line desorption was carried out by direct coupling of the SPE-PTs with the liner of the programmed-temperature va

  17. Photon- and electron-stimulated desorption from laboratory models of interstellar ice grains

    Energy Technology Data Exchange (ETDEWEB)

    Thrower, J. D.; Abdulgalil, A. G. M.; Collings, M. P.; McCoustra, M. R. S.; Burke, D. J.; Brown, W. A.; Dawes, A.; Holtom, P. J.; Kendall, P.; Mason, N. J.; Jamme, F.; Fraser, H. J.; Rutten, F. J. M. [School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh EH 14 4AS (United Kingdom); Department of Chemistry, University College London, 20 Gordon Street, London W1CH 0AJ (United Kingdom); Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); SOLEIL Synchrotron, BP 48, L' Orme des Merisiers, F-91192 Gif surf Yvette Cedex (France); Department of Physics, Scottish Universities Physics Alliance (SUPA), University of Strathclyde, John Anderson Building, 107 Rottenrow East, Glasgow G4 0NG (United Kingdom); School of Pharmacy and iEPSAM, Keele University, Keele ST5 5BG (United Kingdom)

    2010-07-15

    The nonthermal desorption of water from ice films induced by photon and low energy electron irradiation has been studied under conditions mimicking those found in dense interstellar clouds. Water desorption following photon irradiation at 250 nm relies on the presence of an absorbing species within the H{sub 2}O ice, in this case benzene. Desorption cross sections are obtained and used to derive first order rate coefficients for the desorption processes. Kinetic modeling has been used to compare the efficiencies of these desorption mechanisms with others known to be in operation in dense clouds.

  18. Characterization of aromaticity in analogues of titan's atmospheric aerosols with two-step laser desorption ionization mass spectrometry

    CERN Document Server

    Mahjoub, Ahmed; Carrasco, Nathalie; Benilan, Yves; Cernogora, Guy; Szopa, Cyril; Gazeau, Marie-Claire

    2016-01-01

    The role of polycyclic aromatic hydrocarbons (PAH) and Nitrogen containing PAH (PANH) as intermediates of aerosol production in the atmosphere of Titan has been a subject of controversy for a long time. An analysis of the atmospheric emission band observed by the Visible and Infrared Mapping Spectrometer (VIMS) at 3.28 micrometer suggests the presence of neutral polycyclic aromatic species in the upper atmosphere of Titan. These molecules are seen as the counter part of negative and positive aromatics ions suspected by the Plasma Spectrometer onboard the Cassini spacecraft, but the low resolution of the instrument hinders any molecular speciation. In this work we investigate the specific aromatic content of Titan's atmospheric aerosols through laboratory simulations. We report here the selective detection of aromatic compounds in tholins, Titan's aerosol analogues, produced with a capacitively coupled plasma in a N2:CH4 95:5 gas mixture. For this purpose, Two-Step Laser Desorption Ionization Time-of-Flight Ma...

  19. Dust as interstellar catalyst I. Quantifying the chemical desorption process

    CERN Document Server

    Minissale, M; Cazaux, S; Hocuk, S

    2015-01-01

    Context. The presence of dust in the interstellar medium has profound consequences on the chemical composition of regions where stars are forming. Recent observations show that many species formed onto dust are populating the gas phase, especially in cold environments where UV and CR induced photons do not account for such processes. Aims. The aim of this paper is to understand and quantify the process that releases solid species into the gas phase, the so-called chemical desorption process, so that an explicit formula can be derived that can be included into astrochemical models. Methods. We present a collection of experimental results of more than 10 reactive systems. For each reaction, different substrates such as oxidized graphite and compact amorphous water ice are used. We derive a formula to reproduce the efficiencies of the chemical desorption process, which considers the equipartition of the energy of newly formed products, followed by classical bounce on the surface. In part II we extend these resul...

  20. Unconventional resource's production under desorption-induced effects

    Directory of Open Access Journals (Sweden)

    S. Sina Hosseini Boosari

    2016-06-01

    We have developed a numerical model to study the effect of changes in porosity, permeability and compaction on four major U.S. shale formations considering their Langmuir isotherm desorption behavior. These resources include; Marcellus, New Albany, Barnett and Haynesville Shales. First, we introduced a model that is a physical transport of single-phase gas flow in shale porous rock. Later, the governing equations are implemented into a one-dimensional numerical model and solved using a fully implicit solution method. It is found that the natural gas production is substantially affected by desorption-induced porosity/permeability changes and geomechancis. This paper provides valuable insights into accurate modeling of unconventional reservoirs that is more significant when an even small correction to the future production prediction can enormously contribute to the U.S. economy.

  1. Thermal desorption of helium from homogeneously implanted graphite

    Science.gov (United States)

    Jung, P.; Schroeder, H.

    1991-11-01

    Super-fine grain graphite (FGG) and pyrolytic carbon (PYC) of thicknesses around 200 μm were homogeneously implanted at room temperature with α-particles (0.5 MeV ≤ Eα ≤ 22 MeV). Thermal helium desorption spectrometry in the temperature range from 400 to 1900 K can be described by diffusion kinetics with an activation energy of 1.1 eV in FGG and about 0.75 eV in PYC. Desorption during temperature ramping at a constant rate of 0.83 K/s also shows significant differences of the two graphite species. It is found that in FGG and especially in PYC a considerable fraction of the implanted helium is retained even beyond 1000 K. This is in contrast to results reported after low energy implantations to high doses for various graphite species.

  2. Spatially resolved thermal desorption/ionization coupled with mass spectrometry

    Science.gov (United States)

    Jesse, Stephen; Van Berkel, Gary J; Ovchinnikova, Olga S

    2013-02-26

    A system and method for sub-micron analysis of a chemical composition of a specimen are described. The method includes providing a specimen for evaluation and a thermal desorption probe, thermally desorbing an analyte from a target site of said specimen using the thermally active tip to form a gaseous analyte, ionizing the gaseous analyte to form an ionized analyte, and analyzing a chemical composition of the ionized analyte. The thermally desorbing step can include heating said thermally active tip to above 200.degree. C., and positioning the target site and the thermally active tip such that the heating step forms the gaseous analyte. The thermal desorption probe can include a thermally active tip extending from a cantilever body and an apex of the thermally active tip can have a radius of 250 nm or less.

  3. Laser-induced acoustic desorption (LIAD) mass spectrometry.

    Science.gov (United States)

    Dow, Alex M; Wittrig, Ashley R; Kenttämaa, Hilkka I

    2012-01-01

    Large thermally labile molecules were not amenable to mass spectrometric analysis until the development of atmospheric pressure evaporation/ionization methods, such as electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI), since attempts to evaporate these molecules by heating induces degradation of the sample. While ESI and MALDI are relatively soft desorption/ionization techniques, they are both limited to preferential ionization of acidic and basic analytes. This limitation has been the driving force for the development of other soft desorption/ionization techniques. One such method employs laser-induced acoustic desorption (LIAD) to evaporate neutral sample molecules into mass spectrometers. LIAD utilizes acoustic waves generated by a laser pulse in a thin metal foil. The acoustic waves travel through the foil and cause desorption of neutral molecules that have been deposited on the opposite side of the foil. One of the advantages of LIAD is that it desorbs low-energy molecules that can be ionized by a variety of methods, thus allowing the analysis of large molecules that are not amenable to ESI and MALDI. This review covers the generation of acoustic waves in foils via a laser pulse, the parameters affecting the generation of acoustic waves, possible mechanisms for desorption of neutral molecules, as well as the various uses of LIAD by mass spectrometrists. The conditions used to generate acoustic or stress waves in solid materials consist of three regimes: thermal, ablative, and constrained. Each regime is discussed, in addition to the mechanisms that lead to the ablation of the metal from the foil and generation of acoustic waves for two of the regimes. Previously proposed desorption mechanisms for LIAD are presented along with the flaws associated with some of them. Various experimental parameters, such as the exact characteristics of the laser pulse and foil used, are discussed. The internal and kinetic energy of the neutral

  4. Experimental study on desorption of soluble matter as influenced by cations in static water

    Institute of Scientific and Technical Information of China (English)

    Wen-sheng XU; Li CHEN; Xiao-xia TONG; Xiao-ping CHEN; Ping-cang ZHANG

    2014-01-01

    With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as processes of river bed deformation and landform evolution throughout a watershed. In this study, considering influences on sediment movement, especially on cohesive sediment transport, Ca2+ and H+ were chosen as characteristic ions of soluble matter, and the total desorption quantity of Ca2+ and pH value when the desorption equilibrium is reached were employed as two indexes representing the desorption of soluble matter. By means of an indoor experiment, desorption of soluble matter as influenced by cations in static water was investigated. The results show that the total desorption quantity of soluble matter increases with the initial cation concentration until a maximum desorption quantity value is obtained and maintained. The total desorption quantity of soluble matter depends on properties of the specific cations in static water, and the stronger the affinity is between the cation and sediment surface, the higher the total desorption quantity will be. Finally, a strong approximate linear relationship between desorption quantities for different kinds of soluble matters was obtained, which means that variation of pH values can accurately reflect the desorption results of soluble matter.

  5. Sorption/desorption reversibility of polycyclic aromatic hydrocarbons (PAHs) in soils and carbonaceous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohui

    2008-07-01

    Understanding sorption/desorption is an important prerequisite for the prediction of fate and transport of pollutants in the environment. During the last two decades, numerous studies have reported hysteresis phenomenon for the interaction of hydrophobic organic contaminants (HOCs) with natural organic matter (NOM). It manifests as nonsingular sorption/desorption isotherms or different rates for sorption and desorption, where during desorption a higher affinity of a compound on a given sorbent and a longer time scale for release than for sorption is observed. Other studies showed that some of the reported sorption/desorption hysteresis phenomena are due to experimental artifacts, mainly resulting from non-attainment of sorption equilibrium before desorption experiments, which result in 'pseudo-hysteresis'. Except for the hypothesis of sorbent reconfiguration, clear experimental evidence for the physical or chemical mechanisms proposed to lead to hysteresis is still lacking. In this study, sorption/desorption equilibrium and kinetics of phenanthrene sorption/desorption from two soils and three carbonaceous samples were investigated using both batch and column techniques. The main objective of this work was to monitor hysteresis phenomenon by carefully recovering the solute mass in the system and to compare sorption/desorption equilibria and kinetics thermodynamically. Nonsingular isotherms and higher desorption enthalpies as well as increased activation energies with proceeding desorption are expected if significant hysteresis exists. Sorption-desorption cycles were carried out to compare equilibrium isotherms and associated sorption/desorption enthalpies (AeH, isosteric heats). Instead of the traditional decant-and-refill batch method, the experiments were conducted using a newly designed batch protocol, which enables the determination of sorption/desorption isotherms at different temperatures using a closed batch system. This method additionally allows

  6. [Sorption-desorption of phosphate in wastewater by hydrous iron oxide].

    Science.gov (United States)

    Xiang, Xue-Min; Liu, Ying; Zhou, Ji-Ti; Wang, Ren

    2008-11-01

    FeCl3 was used t o prepare hydrous iron oxide (HIO) as a n absorbent for phosphate (P) sorption and desorption study. The results showed that as pH decreased, the sorption capacity of HIO increased, and the sorption kinetics followed the second-order model, and the sorption isotherm could be fitted by the Langmuir equation. A 50 g/L NaOH solution was used for desorption of P from HIO, and the desorption rate could be reached over 98% . No relation was found between desorption rate and adsorption capacity. Based on above results, HIO was applied to adsorption of P from supernatant of sludge thickener, and after desorption, more than 90% of P was recovered. According to the results obtained, an effective system for P removal and recovery from municipal wastewater was suggested, which includes the following processes: adsorption, desorption, regeneration of HIO, and of recovery of P from P-rich desorption solution.

  7. Residence time dependent desorption of Staphylococcus epidermidis from hydrophobic and hydrophilic substrata.

    Science.gov (United States)

    Boks, Niels P; Kaper, Hans J; Norde, Willem; Busscher, Henk J; van der Mei, Henny C

    2008-12-01

    Adhesion and desorption are simultaneous events during bacterial adhesion to surfaces, although desorption is far less studied than adhesion. Here, desorption of Staphylococcus epidermidis from substratum surfaces is demonstrated to be residence time dependent. Initial desorption rate coefficients were similar for hydrophilic and hydrophobic dimethyldichlorosilane (DDS)-coated glass, likely because initial desorption is controlled by attractive Lifshitz-Van der Waals interactions, which are comparable on both substratum surfaces. However, significantly slower decay times of the desorption rate coefficients are found for hydrophilic glass than for hydrophobic DDS-coated glass. This difference is suggested to be due to the acid-base interactions between staphylococci and these surfaces, which are repulsive on hydrophilic glass and attractive on hydrophobic DDS-coated glass. Final desorption rate coefficients are higher on hydrophilic glass than on hydrophobic DDS-coated glass, due to the so called hydrophobic effect, facilitating a closer contact on hydrophobic DDS-coated glass.

  8. Laser Desorption Mass Spectrometry. II. Applications to Structural Analysis.

    Science.gov (United States)

    1982-02-02

    was unexpected, was the quaternary amine Safranin -O. Ions corresponding to (M-HC)- at m/z 313 dominate the negative ion mass spectrum. Two classes of...and cluster species were observed. The positive ion LD mass spectrum of safranin -O, shown in Figure 6, is tvnical of LD results for salts. The...Figure 6. Laser Desorption Positive-ion Spectrum of Safranin 0. Figure 7. Laser Desorntion Mass Spectra of Doubly Charged Organic Salts Top - N,N

  9. Thermodynamic properties of water desorption of forage turnip seeds

    OpenAIRE

    Kelly Aparecida Sousa; Osvaldo Resende; André Luis Duarte Goneli; Thaís Adriana de Souza Smaniotto; Daniel Emanuel Cabral de Oliveira

    2014-01-01

    The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip  seeds. The equilibrium moisture content of forage turnip  seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within ...

  10. Thermodynamic properties of water desorption of forage turnip seeds

    OpenAIRE

    Sousa,Kelly Aparecida de; Resende,Osvaldo; Goneli, André Luis Duarte; Smaniotto,Thaís Adriana de Souza; Oliveira,Daniel Emanuel Cabral de

    2015-01-01

    The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip seeds. The equilibrium moisture content of forage turnip seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within th...

  11. Ammonia nitrogen desorption from sanitary landfill leachate in filling towers

    OpenAIRE

    Leite,Valderi D.; Barros,Aldre J. M.; Lopes,Wilton S.; Sousa,José T. de

    2014-01-01

    Sanitary landfill leachates present high concentrations of carbonaceous and nitrogenous materials. The crucial point is that carbonaceous materials are of difficult biodegradation, what compromises the performance of biological treatment processes, while nitrogenous materials, such as ammonia nitrogen, probably preclude the use of biological treatments. Therefore, the aim of this work was to study the desorption process of ammonia nitrogen from sanitary landfill leachate in filling towers. De...

  12. Study on adsorption and desorption of ammonia on graphene

    Science.gov (United States)

    Zhang, Zhengwei; Zhang, Xinfang; Luo, Wei; Yang, Hang; He, Yanlan; Liu, Yixing; Zhang, Xueao; Peng, Gang

    2015-09-01

    The gas sensor based on pristine graphene with conductance type was studied theoretically and experimentally. The time response of conductance measurements showed a quickly and largely increased conductivity when the sensor was exposed to ammonia gas produced by a bubble system of ammonia water. However, the desorption process in vacuum took more than 1 h which indicated that there was a larger number of transferred carriers and a strong adsorption force between ammonia and graphene. The desorption time could be greatly shortened down to about 2 min by adding the flow of water-vapor-enriched air at the beginning of the recovery stage which had been confirmed as a rapid and high-efficiency desorption process. Moreover, the optimum geometries, adsorption energies, and the charge transfer number of the composite systems were studied with first-principle calculations. However, the theoretical results showed that the adsorption energy between NH3 and graphene was too small to fit for the experimental phenomenon, and there were few charges transferred between graphene and NH3 molecules, which was completely different from the experiment measurement. The adsorption energy between NH4 and graphene increased stage by stage which showed NH4 was a strong donor. The calculation suggested that H2O molecule could help a quick desorption of NH4 from graphene by converting NH4 to NH3 or (NH3)n(H2O)m groups, which was consistent with the experimental results. This study demonstrates that the ammonia gas produced by a bubble system of ammonia water is mainly ammonium groups of NH3 and NH4, and the NH4 moleculars are ideal candidates for the molecular doping of graphene while the interaction between graphene and the NH3 moleculars is weak.

  13. Temperature Effect on Boron Adsorption—Desorption Kinetics in Soils

    Institute of Scientific and Technical Information of China (English)

    ZHUDUANWEI; SHILEI; 等

    1999-01-01

    The effect of temperature on the properties of boron adsorption-desorption in brown-red soil,yellowbrown soil and calcareous alluvial soil of Hubei Province was investigated with the mobile displacement technique.The experimental data of B adsorption-desorption amounts and reaction time at 25 and 40℃ were fitted by the zero-order,first-order and parabolic diffusion kinetic equations.The adsorption process was in conformity with the parabolic diffusion law at both the temperatures,and the values of rate constant of the parabolic diffusion equation in B adsorption were 0.138,0.124 and 0.105 mg kg-1 min-1/2 at 25℃,and 0.147,0.146and 0.135mg kg-1 min1/2 at 40℃ for the brown-red soil,yellow-brown soil,and calcareous alluvial soil,respectively,The relationship between amount of B desorption and reaction time could be well described by the first-order kinetic equation,and the corresponding values of rate constant were 0.0422,0.0563 and 0.0384min-1 at 25℃,and 0.0408,0.0423 and 0.0401min-1 at 40℃ for the brown-red soil,the yellow-brown soil and the calcareous alluvial soil,respectively.Therefore,the desorption process of B might be related to the amount of B adsorbed in soil,The higher th temperature,the lower the amount of B adsorption of the same soil in the same reaction time,The values of the apparent activation energy of B adsorption in the three soils calculated with the rate constants of parabolic diffusion equation were 3.27,8.44 and 12.99 kJ mol-1,respectively,based on the experimental data of B adsorption amounts and reaction time at and 40℃.

  14. Study on adsorption and desorption of ammonia on graphene.

    Science.gov (United States)

    Zhang, Zhengwei; Zhang, Xinfang; Luo, Wei; Yang, Hang; He, Yanlan; Liu, Yixing; Zhang, Xueao; Peng, Gang

    2015-12-01

    The gas sensor based on pristine graphene with conductance type was studied theoretically and experimentally. The time response of conductance measurements showed a quickly and largely increased conductivity when the sensor was exposed to ammonia gas produced by a bubble system of ammonia water. However, the desorption process in vacuum took more than 1 h which indicated that there was a larger number of transferred carriers and a strong adsorption force between ammonia and graphene. The desorption time could be greatly shortened down to about 2 min by adding the flow of water-vapor-enriched air at the beginning of the recovery stage which had been confirmed as a rapid and high-efficiency desorption process. Moreover, the optimum geometries, adsorption energies, and the charge transfer number of the composite systems were studied with first-principle calculations. However, the theoretical results showed that the adsorption energy between NH3 and graphene was too small to fit for the experimental phenomenon, and there were few charges transferred between graphene and NH3 molecules, which was completely different from the experiment measurement. The adsorption energy between NH4 and graphene increased stage by stage which showed NH4 was a strong donor. The calculation suggested that H2O molecule could help a quick desorption of NH4 from graphene by converting NH4 to NH3 or (NH3)n(H2O)m groups, which was consistent with the experimental results. This study demonstrates that the ammonia gas produced by a bubble system of ammonia water is mainly ammonium groups of NH3 and NH4, and the NH4 moleculars are ideal candidates for the molecular doping of graphene while the interaction between graphene and the NH3 moleculars is weak.

  15. Laser Desorption Postionization for Imaging MS of Biological Material

    OpenAIRE

    Akhmetov, Artem; Moore, Jerry F.; Gasper, Gerald L.; Koin, Peter J.; Hanley, Luke

    2010-01-01

    Vacuum ultraviolet single photon ionization (VUV SPI) is a soft ionization technique that has the potential to address many of the limitations of MALDI for imaging MS. Laser desorption postionization (LDPI) employs VUV SPI for postionization and is experimentally analogous to a MALDI instrument with the addition of a pulsed VUV light source. This review discusses progress in LDPI-MS over the last decade, with an emphasis on imaging MS of bacterial biofilms, analytes whose high salt environmen...

  16. Dicyandiamide Sorption-Desorption Behavior on Soils and Peat Humus

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hai-Jun; WU Zhi-Jie; ZHOU Qi-Xing

    2004-01-01

    The sorption-desorption behavior of dicyandiamide (DCD) is an important chemical process that affects DCD fate and mobility in soils. Therefore, this study quantified DCD sorption-desorption on a phaeozem (Mollisol), a burozem (Alfisol), a soil with organic matter-removed and peat humus using the batch-equilibration procedure, and identified soil properties that influenced DCD sorption. The sorption on peat humus was higher than that on the phaeozem and the burozem, with much lower sorption observed on the soil with organic matter-removed, indicating that soil organic matter was the main carrier of DCD sorption. Due to its amphipathic property the DCD molecule sorption on the phaeozem and the burozem decreased as pH increased from about 2 to 5, but a further increase in pH led to a rise in DCD sorption.The DCD desorption hysteretic effect for peat humus was greater than that for the phaeozem and the burozem using 0.01 mol L-1 CaC12 as the background electrolyte, suggesting that the hydrophobic domains of organic matter may play an important role in DCD sorption.

  17. Thermodynamic properties of water desorption of forage turnip seeds

    Directory of Open Access Journals (Sweden)

    Kelly Aparecida Sousa

    2014-11-01

    Full Text Available The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip  seeds. The equilibrium moisture content of forage turnip  seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within the moisture content range of 3.33 to 11.30 (% d.b., varies from 4,222.70 to 2,870.34 kJ kg-1. With the elevation in the equilibrium moisture content, there is an increase in differential entropy and Gibbs free energy, which has positive values, demonstrating non-spontaneity in the process of desorption in the seeds. The theory of enthalpy-entropy compensation can be satisfactorily applied to the sorption phenomenon, and the process of water desorption of forage turnip seeds is controlled by enthalpy.

  18. Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys

    Science.gov (United States)

    Urgnani, J.; Di Chio, M.; Palumbo, M.; Feuerbacher, M.; Fernandez, J. F.; Leardini, F.; Baricco, M.

    2009-01-01

    The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H2 absorption/desorption kinetics. In this paper, the interaction of H2 with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg38.5Al61.5, Mg69Al31 and Mg72Al28. For Mg72Al28, no significant changes in the microstructure have been obtained by rapid solidification. In Mg69Al31, a significant grain refinement has been observed, whereas, for Mg38.5Al61.5, the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H2 absorption, leading to MgH2. After heating up to 430 °C the hydrogenated samples, a main desorption reaction from MgH2 has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.

  19. Adsorption and desorption of bivalent metals to hematite nanoparticles.

    Science.gov (United States)

    Grover, Valerie A; Hu, Jinxuan; Engates, Karen E; Shipley, Heather J

    2012-01-01

    The use of commercially prepared hematite nanoparticles (37.0 nm) was studied as an adsorbent in the removal of Cd(II), Cu(II), Pb(II), and Zn(II) from aqueous solutions. Single-metal adsorption was studied as a function of metal and adsorbent concentrations, whereas binary metal competition was found to be dependent on the molar ratio between the competing metals. Competitive effects indicated that Pb had strong homogenous affinity to the nanohematite surface, and decreased adsorption of Cd, Cu, and Zn occurred when Pb was present in a binary system. Metal adsorption strength to nanohematite at pH 6.0 increased with metal electronegativity: Pb > Cu > Zn ∼ Cd. Equilibrium modeling revealed that the Langmuir-Freundlich composite isotherm adequately described the adsorption and competitive effects of metals to nanohematite, whereas desorption was best described by the Langmuir isotherm. The desorption of metals from nanohematite was found to be pH dependent, with pH 4.0 > pH 6.0 > pH 8.0, and results showed that greater than 65% desorption was achieved at pH 4.0 within three 24-h cycles for all metals.

  20. Laser desorption lamp ionization source for ion trap mass spectrometry.

    Science.gov (United States)

    Wu, Qinghao; Zare, Richard N

    2015-01-01

    A two-step laser desorption lamp ionization source coupled to an ion trap mass spectrometer (LDLI-ITMS) has been constructed and characterized. The pulsed infrared (IR) output of an Nd:YAG laser (1064 nm) is directed to a target inside a chamber evacuated to ~15 Pa causing desorption of molecules from the target's surface. The desorbed molecules are ionized by a vacuum ultraviolet (VUV) lamp (filled with xenon, major wavelength at 148 nm). The resulting ions are stored and detected in a three-dimensional quadrupole ion trap modified from a Finnigan Mat LCQ mass spectrometer operated at a pressure of ≥ 0.004 Pa. The limit of detection for desorbed coronene molecules is 1.5 pmol, which is about two orders of magnitude more sensitive than laser desorption laser ionization mass spectrometry using a fluorine excimer laser (157 nm) as the ionization source. The mass spectrum of four standard aromatic compounds (pyrene, coronene, rubrene and 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (OPC)) shows that parent ions dominate. By increasing the infrared laser power, this instrument is capable of detecting inorganic compounds.

  1. New perspectives in vacuum high voltage insulation. II. Gas desorption

    CERN Document Server

    Diamond, W T

    1998-01-01

    An examination has been made of gas desorption from unbaked electrodes of copper, niobium, aluminum, and titanium subjected to high voltage in vacuum. It has been shown that the gas is composed of water vapor, carbon monoxide, and carbon dioxide, the usual components of vacuum outgassing, plus an increased yield of hydrogen and light hydrocarbons. The gas desorption was driven by anode conditioning as the voltage was increased between the electrodes. The gas is often desorbed as microdischarges-pulses of a few to hundreds of microseconds-and less frequently in a more continuous manner without the obvious pulsed structure characteristic of microdischarge activity. The quantity of gas released was equivalent to many monolayers and consisted mostly of neutral molecules with an ionic component of a few percent. A very significant observation was that the gas desorption was more dependent on the total voltage between the electrodes than on the electric field. It was not triggered by field-emitted electrons but oft...

  2. Rapid decompression and desorption induced energetic failure in coal

    Directory of Open Access Journals (Sweden)

    Shugang Wang

    2015-06-01

    Full Text Available In this study, laboratory experiments are conducted to investigate the rapid decompression and desorption induced energetic failure in coal using a shock tube apparatus. Coal specimens are recovered from Colorado at a depth of 610 m. The coal specimens are saturated with the strong sorbing gas CO2 for a certain period and then the rupture disc is suddenly broken on top of the shock tube to generate a shock wave propagating upwards and a rarefaction wave propagating downwards through the specimen. This rapid decompression and desorption has the potential to cause energetic fragmentation in coal. Three types of behaviors in coal after rapid decompression are found, i.e. degassing without fragmentation, horizontal fragmentation, and vertical fragmentation. We speculate that the characteristics of fracture network (e.g. aperture, spacing, orientation and stiffness and gas desorption play a role in this dynamic event as coal can be considered as a dual porosity, dual permeability, dual stiffness sorbing medium. This study has important implications in understanding energetic failure process in underground coal mines such as coal gas outbursts.

  3. Thermal Desorption of Water-Ice in the Interstellar Medium

    CERN Document Server

    Fraser, H J; McCoustra, M R S; Williams, D A; Fraser, Helen J.; Collings, Mark P.; Coustra, Martin R.S. Mc; Williams, David A.

    2001-01-01

    Water (H2O) ice is an important solid constituent of many astrophysical environments. To comprehend the role of such ices in the chemistry and evolution of dense molecular clouds and comets, it is necessary to understand the freeze-out, potential surface reactivity, and desorption mechanisms of such molecular systems. Consequently, there is a real need from within the astronomical modelling community for accurate empirical molecular data pertaining to these processes. Here we give the first results of a laboratory programme to provide such data. Measurements of the thermal desorption of H2O ice, under interstellar conditions, are presented. For ice deposited under conditions that realistically mimic those in a dense molecular cloud, the thermal desorption of thin films (~50 molecular layers) is found to occur with zero order kinetics characterised by a surface binding energy, E_{des}, of 5773 +/- 60 K, and a pre-exponential factor, A, of 10^(30 +/- 2) molecules cm^-2 s^-1. These results imply that, in the den...

  4. Sorption and desorption of silver ions by bentonite clays.

    Science.gov (United States)

    Constantino, Leonel Vinicius; Quirino, Juliana Nunes; Monteiro, Alessandra Maffei; Abrão, Taufik; Parreira, Paulo Sérgio; Urbano, Alexandre; Santos, Maria Josefa

    2017-04-01

    Anthropogenic activities have increased the concentration of metal species in the environment. The toxicity of silver ions to aquatic and terrestrial organisms has required monitoring by analytical methods, besides actions to promote its control as pollutant. Sorption and desorption processes are directly related to the mobility and availability of metal ions in the environment. In this context, clay minerals can be used for pre-concentration, removal and recovery of silver ions from aqueous solution. Herein, two bentonite clays (BaVC-1 and SWy-2) were characterised and applied to investigate the sorption and desorption of silver ions. Isotherms were fitted to the dual-mode Langmuir-Freundlich model to qualify and quantify sorption sites and evaluate the mobilisation process. The maximum sorption capacity was 743 and 849 meq kg(-1) for BaVC-1 and SWy-2, respectively. Hysteresis index (HI) and mobilisation factor (MF) suggest that the desorption of silver ions in BaVC-1 is about four times more conducive compared to that in SWy-2, although both materials have demonstrated a great potential for Ag(+) pre-concentration from aqueous solutions.

  5. Improved hydrogen desorption from lithium hydrazide by alkali metal hydride

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Liang, E-mail: liangzeng@hiroshima-u.ac.jp [Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Miyaoka, Hiroki [Institute for Sustainable Sciences and Development, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Ichikawa, Takayuki; Kojima, Yoshitsugu [Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan)

    2013-12-15

    Highlights: •LiH can dramatically improve the hydrogen desorption properties of LiNHNH{sub 2}. •KH doping had positive effect in promoting the hydrogen desorption properties of LiNHNH{sub 2}–LiH mixture. •The reaction mechanism between LiNHNH{sub 2} and LiH was studied and discussed. -- Abstract: Lithium hydrazide (LiNHNH{sub 2}), which is a white solid with 8.0 mass% of theoretical hydrogen content, was synthesized from a reaction between anhydrous hydrazine and n-butyllithium in diethyl ether. The thermodynamic properties of this compound and its detailed decomposition pathways had been investigated in our previous work. However, a number of undesired gaseous products such as hydrazine (N{sub 2}H{sub 4}) and ammonia (NH{sub 3}) were generated during the thermal decomposition of LiNHNH{sub 2}. In this work, alkali metal hydride was used to suppress the impurities in the desorbed hydrogen and improved the hydrogen desorption properties. The reaction mechanism between LiNHNH{sub 2} and LiH was also studied and discussed in this paper.

  6. Thermal desorption of circumstellar and cometary ice analogs

    CERN Document Server

    Martín-Doménech, Rafael; Bueno, Juan; Goesmann, Fred

    2014-01-01

    Thermal annealing of interstellar ices takes place in several stages of star formation. Knowledge of this process comes from a combination of astronomical observations and laboratory simulations under astrophysically relevant conditions. For the first time we present the results of temperature programmed desorption (TPD) experiments with pre-cometary ice analogs composed of up to five molecular components: H2 O, CO, CO2, CH3 OH, and NH3 . The experiments were performed with an ultra-high vacuum chamber. A gas line with a novel design allows the controlled preparation of mixtures with up to five molecular components. Volatiles desorbing to the gas phase were monitored using a quadrupole mass spectrometer, while changes in the ice structure and composition were studied by means of infrared spectroscopy. The TPD curves of water ice containing CO, CO2, CH3 OH, and NH3 present desorption peaks at temperatures near those observed in pure ice experiments, volcano desorption peaks after water ice crystallization, and...

  7. Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Urgnani, J; Di Chio, M; Palumbo, M; Baricco, M [Dipartimento di Chimica I.F.M. and NIS, Universita di Torino, via P. Giuria, 10125, Torino (Italy); Feuerbacher, M [Institut fuer Mikrostrukturforschung, Forschungszentrum Juelich GmbH, Leo-Brand- Strasse, 52428 Juelich (Germany); Fernandez, J F; Leardini, F, E-mail: jacopo.urgnani@unito.i [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049, Madrid (Spain)

    2009-01-01

    The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H{sub 2} absorption/desorption kinetics. In this paper, the interaction of H{sub 2} with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg{sub 38.5}Al{sub 61.5}, Mg{sub 69}Al{sub 31} and Mg{sub 72}Al{sub 28}. For Mg{sub 72}Al{sub 28}, no significant changes in the microstructure have been obtained by rapid solidification. In Mg{sub 69}Al{sub 31}, a significant grain refinement has been observed, whereas, for Mg{sub 38.5}Al{sub 61.5}, the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H{sub 2} absorption, leading to MgH{sub 2}. After heating up to 430 deg. C the hydrogenated samples, a main desorption reaction from MgH{sub 2} has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.

  8. Trapping, migration and desorption of helium in tungsten: influence of the implantation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Debelle, A.; Barthe, M.F.; Sauvage, T.; Desgardin, P. [CERI, Centre d' Etudes et de Recherches par Irradiation, CNRS, 45 - Orleans (France); Peaucelle, C. [Lyon-1 Univ. Claude Bernard, CNRS/IN2P3/IPNL, 69 - Villeurbanne (France)

    2007-07-01

    Full text of publication follows: In the future International Thermonuclear Experimental Reactor (ITER), tungsten, due to its physical intrinsic properties, is a potential divertor candidate. The divertor, as a plasma-facing component, will be subjected to intense irradiations at high temperature. In the specific case of fusion reactor, high 14 MeV neutrons flux will cause the continuous production of both H and He by (n,p) and (n,{alpha}) nuclear reactions, and of irradiation-induced defects by recoils. Thus, it appears of crucial interest to study the He behaviour in tungsten introduced in such conditions, that means implanted at high energy and low fluences, and its evolution in temperature. To address this issue, polycrystalline and single crystal tungsten samples were {sup 3}He implanted, at room temperature, at different energies and fluences, ranging from 60 to 500 keV and 2x10{sup 13} to 10{sup 16} cm{sup -2} respectively. Then, thermal annealings upon different conditions (up to 1870 K) were carried out. Lateral distributions, depth profiling and desorption curves measurements of the implanted helium were performed using the {sup 3}He(d,{alpha}){sup 1}H nuclear reaction technique. Results show that, whatever the implantation conditions, helium is trapped during implantation, presumably at vacancy-type defects. However, the nature and consequently the stability of the helium-vacancy-like complexes differ. At high energy, the complexes are highly stable, and no desorption is observed after annealing up to 1773 K. A helium migration over a weak length is nonetheless noticed, as deduced from the comparison of the depth profiles, and attributed to the migration of the complexes. At low energy, a helium desorption is detected for annealing temperatures higher than 1470 K. It is very likely that under these conditions, simple HeV complexes are formed during implantation. Results obtained from a positron annihilation spectroscopy study on the implantation

  9. Study of the mechanisms of heavy-ion induced desorption on accelerator-relevant materials; Untersuchung der Mechanismen schwerioneninduzierter Desorption an beschleunigerrelevanten Materialien

    Energy Technology Data Exchange (ETDEWEB)

    Bender, Markus

    2008-02-22

    The ion beam loss induced desorption is a performance limitation for low charge state heavy ion accelerators. If charge exchanged projectile ions get lost onto the beam pipe, desorption of gas is stimulated resulting in a pressure increase inside of the synchrotron and thus, a dramatically reduction of the beam life time. To minimize the amount of desorbed gas an experimental program has been started to measure the desorption yields (released gas molecules per incident ion) of various materials and different projectile ions. The present work is a contribution to the understanding of the physical processes behind the ion beam loss induced desorption. The yield measurements by the pressure rise method have been combined for the rst time with in situ ion beam analysis technologies such as ERDA and RBS. With this unique method the desorption behavior of a sample can be correlated to its surface and bulk properties. The performed experiments with 1,4 MeV/u Xenon-Ions show that the ion induced desorption is mainly a surface effect. Sputtered oxide layers or impurities do not contribute to the desorbed gas significantly. Nevertheless bulk properties play an important role in the desorption strength. Pure metallic samples desorb less gas than isolating materials under swift heavy ion irradiation. From the experimental results it was possible to estimate the desorption yields of various materials under ion bombardment by means of an extended inelastic thermal-spike-model. The extension is the combination of the thermal-spike's temperature map with thermal desorption. Within this model the ion induced desorption can be regarded as the release of adsorbates from a transient overheated spot on the samples surface around the ion impact. Finally a copper substrate with a gold coated surface was developed and proposed as a suitable material for a beam loss collimator with minimum desorption to ensure the performance of GSI's SIS18 in high current beam operation. (orig.)

  10. Particle balance in long duration RF driven plasmas on QUEST

    Energy Technology Data Exchange (ETDEWEB)

    Hanada, K., E-mail: hanada@triam.kyushu-u.ac.jp [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Zushi, H.; Yoshida, N. [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Yugami, N.; Honda, T. [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan); Hasegawa, M. [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Mishra, K. [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan); Kuzmin, A.; Nakamura, K.; Fujisawa, A.; Idei, H.; Nagashima, Y.; Watanabe, O.; Onchi, T.; Watanabe, H.; Tokunaga, K.; Higashijima, A.; Kawasaki, S.; Nakashima, H. [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 812-8580 (Japan); Takase, Y. [Graduate School of Frontier Science, University of Tokyo (Japan); and others

    2015-08-15

    Global particle balance in non-inductive long-duration plasma on QUEST has been investigated. Approximately 70% of the fuel hydrogen (H) was retained in the wall and then was almost exhausted just after the discharge. The global recycling ratio (R{sub g}), defined as the ratio of the evacuated H{sub 2} flux to that injected, was found to gradually increase during discharges and subsequently rose rapidly. To study the growth of R{sub g}, the thermal desorption spectra after deuterium implantation in a specimen exposed to QUEST plasma was analyzed with a model which includes reflection, diffusion, solution, recombination, trapping, and plasma-induced desorption in the re-deposition layer. The model reconstructs the growth of R{sub g} during a long-duration plasma and indicates solution plays a dominant role in the growth.

  11. Sorption/desorption reversibility of polycyclic aromatic hydrocarbons (PAHs) in soils and carbonaceous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohui

    2008-07-01

    Understanding sorption/desorption is an important prerequisite for the prediction of fate and transport of pollutants in the environment. During the last two decades, numerous studies have reported hysteresis phenomenon for the interaction of hydrophobic organic contaminants (HOCs) with natural organic matter (NOM). It manifests as nonsingular sorption/desorption isotherms or different rates for sorption and desorption, where during desorption a higher affinity of a compound on a given sorbent and a longer time scale for release than for sorption is observed. Other studies showed that some of the reported sorption/desorption hysteresis phenomena are due to experimental artifacts, mainly resulting from non-attainment of sorption equilibrium before desorption experiments, which result in 'pseudo-hysteresis'. Except for the hypothesis of sorbent reconfiguration, clear experimental evidence for the physical or chemical mechanisms proposed to lead to hysteresis is still lacking. In this study, sorption/desorption equilibrium and kinetics of phenanthrene sorption/desorption from two soils and three carbonaceous samples were investigated using both batch and column techniques. The main objective of this work was to monitor hysteresis phenomenon by carefully recovering the solute mass in the system and to compare sorption/desorption equilibria and kinetics thermodynamically. Nonsingular isotherms and higher desorption enthalpies as well as increased activation energies with proceeding desorption are expected if significant hysteresis exists. Sorption-desorption cycles were carried out to compare equilibrium isotherms and associated sorption/desorption enthalpies (AeH, isosteric heats). Instead of the traditional decant-and-refill batch method, the experiments were conducted using a newly designed batch protocol, which enables the determination of sorption/desorption isotherms at different temperatures using a closed batch system. This method additionally allows

  12. Desorption Kinetics and Mechanisms of CO2 on Amine-Based Mesoporous Silica Materials

    Directory of Open Access Journals (Sweden)

    Yang Teng

    2017-01-01

    Full Text Available Tetraethylenepentamine (TEPA-based mesoporous MCM-41 is used as the adsorbent to determine the CO2 desorption kinetics of amine-modified materials after adsorption. The experimental data of CO2 desorption as a function of time are derived by zero-length column at different temperatures (35, 50, and 70 °C and analyzed by Avrami’s fractional-order kinetic model. A new method is used to distinguish the physical desorption and chemical desorption performance of surface-modified mesoporous MCM-41. The activation energy Ea of CO2 physical desorption and chemical desorption calculated from Arrhenius equation are 15.86 kJ/mol and 57.15 kJ/mol, respectively. Furthermore, intraparticle diffusion and Boyd’s film models are selected to investigate the mechanism of CO2 desorption from MCM-41 and surface-modified MCM-41. For MCM-41, there are three rate-limiting steps during the desorption process. Film diffusion is more prominent for the CO2 desorption rates at low temperatures, and pore diffusion mainly governs the rate-limiting process under higher temperatures. Besides the surface reaction, the desorption process contains four rate-limiting steps on surface-modified MCM-41.

  13. Plasma turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Horton, W. [Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies; Hu, G. [Globalstar LP, San Jose, CA (United States)

    1998-07-01

    The origin of plasma turbulence from currents and spatial gradients in plasmas is described and shown to lead to the dominant transport mechanism in many plasma regimes. A wide variety of turbulent transport mechanism exists in plasmas. In this survey the authors summarize some of the universally observed plasma transport rates.

  14. Glyphosate sorption and desorption in soils with distinct phosphorus levels

    Energy Technology Data Exchange (ETDEWEB)

    Prata, Fabio [BIOAGRI Labs., Piracicaba, SP (Brazil). Div. de Quimica. Lab. de Radioquimica; Cardinali, Vanessa Camponez do Brasil; Tornisielo, Valdemar Luiz; Regitano, Jussara Borges [Sao Paulo Univ., Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz. Dept. de Ciencias Exatas; Lavorenti, Arquimedes [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Secao de Toxicologia

    2003-03-01

    The sorption of glyphosate by soils occurs due to the inner sphere complex formation with metals of soil oxides, which are related to the soil phosphate adsorption capacity. The aim of this study was to evaluate the effects of increasing rates of phosphorus on sorption and desorption of glyphosate in three soils with different mineralogical attributes. Soils were a Rhodic Kandiudalf, an Anionic Acrudox and a Typic Humaquept. Soil samples were amended with Kh{sub 2}PO{sub 4} at equivalent rates of 0; 1,000; 5,000; 20,000 and 50,000 kg ha{sup -1} of P{sub 2}O{sub 5}, which are high from the agricultural point of view, but necessary in order to perform sorption and desorption studies. The experimental design consisted of a completely randomized factorial: 2 soils x 5 phosphorus rates and 3 replicates. For the sorption experiments, five glyphosate solutions were employed (0.42; 0.84; 1.68; 3.36 and 6.72 mg L{sup -1}), with a {sup 14}C radioactivity of 0.233 kBq mL{sup -1}. Four steps of the desorption procedures withCaCl{sub 2} 0.01 mol L{sup -1} and one extraction with Mehlich 3 were performed only at one concentration (0.84 mol L{sup -1}). Soil samples were afterwards biologically oxidized to establish the radioactive balance. Glyphosate competes with phosphorus for specific sorption sites, but this competition becomes important when phosphorus is present at rates higher than 1,000 mg dm{sup -3}. Moreover, a small amount of applied glyphosate was extracted (<10%), and the extraction increased with increasing soil phosphorus content. (author)

  15. Glyphosate sorption and desorption in soils with distinct phosphorus levels

    Directory of Open Access Journals (Sweden)

    Prata Fábio

    2003-01-01

    Full Text Available The sorption of glyphosate by soils occurs due to the inner sphere complex formation with metals of soil oxides, which are related to the soil phosphate adsorption capacity. The aim of this study was to evaluate the effects of increasing rates of phosphorus on sorption and desorption of glyphosate in three soils with different mineralogical attributes. Soils were a Rhodic Kandiudalf, an Anionic Acrudox and a Typic Humaquept. Soil samples were amended with KH2PO4 at equivalent rates of 0; 1,000; 5,000; 20,000 and 50,000 kg ha-1 of P2O5, which are high from the agricultural point of view, but necessary in order to perform sorption and desorption studies. The experimental design consisted of a completely randomized factorial: 2 soils x 5 phosphorus rates and 3 replicates. For the sorption experiments, five glyphosate solutions were employed (0.42; 0.84; 1.68; 3.36 and 6.72 mg L-1, with a 14C radioactivity of 0.233 kBq mL-1. Four steps of the desorption procedure with CaCl2 0.01 mol L-1 and one extraction with Mehlich 3 were performed only at one concentration (0.84 mol L-1. Soil samples were afterwards biologically oxidized to establish the radioactive balance. Glyphosate competes with phosphorus for specific sorption sites, but this competition becomes important when phosphorus is present at rates higher than 1,000 mg dm-3. Moreover, a small amount of applied glyphosate was extracted (<10%, and the extraction increased with increasing soil phosphorus content.

  16. Determination of Surface Exciton Energies by Velocity Resolved Atomic Desorption

    Energy Technology Data Exchange (ETDEWEB)

    Hess, Wayne P.; Joly, Alan G.; Beck, Kenneth M.; Sushko, Petr V.; Shluger, Alexander L.

    2004-08-20

    We have developed a new method for determining surface exciton band energies in alkali halides based on velocity-resolved atomic desorption (VRAD). Using this new method, we predict the surface exciton energies for K1, KBr, KC1, and NaC1 within +0.15 eV. Our data, combined with the available EELS data for alkali fluorides, demonstrate a universal linear correlation with the inverse inter-atomic distance in these materials. The results suggest that surface excitons exist in all alkali halides and their excitation energies can be predicted from the known bulk exciton energies and the obtained correlation plot.

  17. Temperature-programmed desorption for membrane inlet mass spectrometry

    DEFF Research Database (Denmark)

    Ketola, R.A.; Grøn, C.; Lauritsen, F.R.

    1998-01-01

    We present a novel technique for analyzing volatile organic compounds in air samples using a solid adsorbent together with temperature-programmed desorption and subsequent detection by membrane inlet mass spectrometry (TPD-MIMS). The new system has the advantage of a fast separation of compounds...... prior to the detection by MIMS. The gaseous sample is simply adsorbed on the adsorbent, which is then rapidly heated from 30 degrees C to 250 degrees C at a rate of 50 degrees C/min, Trapped organic compounds are released from the adsorbent into a helium stream at different temperatures depending...

  18. Desorption Techniques for Determination of Metals Mobility in Soils

    Directory of Open Access Journals (Sweden)

    P. Bartoš

    2002-01-01

    Full Text Available Three leaching techniques for assessment of fixed and mobile metal or radionuclides in soils are demonstrated on radiocaesium speciation. A new leaching technique based on the variation of the leaching solution volume to solid phase amount is proposed. It enables parallel treatment of large numbers of samples and, therefore, is suitable for a routine analysis of contaminant mobility in soils. As a leaching solution, 1 M ammonium acetate is proposed for caesium, but any other desorption solution harmonised with existing speciation schemes can be used.

  19. DESORPTION OF VOCs FROM POLYMERIC ADSORBENTS UNDER MICROWAVE FIELD

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Desorption of volatile organic compounds (VOCs)from polymeric adsorbents by microwave was investigated experimentally. Two kinds of organic compounds, benzene and toluene,were separately used as adsorbates in this work. Results showed that the application of microwave to regenerate the polymeric adsorbents not only can get higher regeneration efficiency in comparison with the use of heat regeneration, but also make the temperatures of the fixed beds much lower than that when using the heat regeneratton The weaker the polarity of a polymeric adsorbent, the easier its regeneration was.

  20. DESORPTION OF VOCs FROM POLYMERIC ADSORBENTS UNDER MICROWAVE FIELD

    Institute of Scientific and Technical Information of China (English)

    LIXiang; LIZhong; 等

    2001-01-01

    Desorption of volatile organic compounds(VOCs) from polymeric adsorbents by microwave was investigated experimentally.Two kinds of organic compounds.benzene and toluene.were separately used as adsorbates in this work Results showed that the application of microwave to regenerate the polymeric adsorbents not only can get higher regeneration efficiency in comparison with the use of heat regeneration,but also make the temperatures of the fixed beds much lower than that when using the heat regeneration the weaker the polarity of a polymericadsorbent,the easier its regeneration was.

  1. Surface oxidation and water desorption of CdS

    Institute of Scientific and Technical Information of China (English)

    陈正石; 李庆霖; 金振声

    1996-01-01

    The surface oxidation and HP desorption of powder CdS were studied by means of X-ray photoetectron spectroscopy (XPS), quadrupole mass spectrometry (QMS) and in-situ FTIR. The results show that with the changes of surface composition and the elongation of store time of CdS there are four types of H2O thermally desorbed at different temperatures. It has also been found that through high-temperature air treatment for a short time the oxidized surface layer of CdS can prevent O2 and H2O in air from further attacking the inner CdS molecules.

  2. Orbital dynamics of a solar sail accelerated by thermal desorption of coatings

    OpenAIRE

    2016-01-01

    In this study we considered a solar sail coated with materials that undergo thermal desorption at a specific temperature, as a result of heating by solar radiation at a particular heliocentric distance. Three different scenarios, that only differ in the way the sail approaches the Sun, were analyzed and compared. In every case once the perihelion is reached, the sail coat undergoes thermal desorption. When the desorption process ends, the sail then escapes the Solar System having the conventi...

  3. Site Specificity in Femtosecond Laser Desorption of Neutral H Atoms from Graphite(0001)

    DEFF Research Database (Denmark)

    Frigge, R.; Hoger, T.; Siemer, B.;

    2010-01-01

    Femtosecond laser excitation and density functional theory reveal site and vibrational state specificity in neutral atomic hydrogen desorption from graphite induced by multiple electronic transitions. Multimodal velocity distributions witness the participation of ortho and para pair states...... of chemisorbed hydrogen in the desorption process. Very slow velocities of 700 and 400  ms-1 for H and D atoms are associated with the desorption out of the highest vibrational state of a barrierless potential....

  4. Desorption of metals from Cetraria islandica (L. Ach. Lichen using solutions simulating acid rain

    Directory of Open Access Journals (Sweden)

    Čučulović Ana A.

    2014-01-01

    Full Text Available Desorption of metals K, Al, Ca, Mg, Fe, Ba, Zn, Mn, Cu and Sr from Cetraria islandica (L. with solutions whose composition was similar to that of acid rain, was investigated. Desorption of metals from the lichen was performed by five successive desorption processes. Solution mixtures containing H2SO4, HNO3 and H2SO4-HNO3 were used for desorption. Each solution had three different pH values: 4.61, 5.15 and 5.75, so that the desorptions were performed with nine different solutions successively five times, always using the same solution volume. The investigated metals can be divided into two groups. One group was comprised of K, Ca and Mg, which were desorbed in each of the five desorption processes at all pH values used. The second group included Al, Fe, Zn, Ba, Mn and Sr; these were not desorbed in each individual desorption and not at all pH values, whereas Cu was not desorbed at all under any circumstances. Using the logarithmic dependence of the metal content as a function of the desorption number, it was found that potassium builds two types of links and is connected with weaker links in lichen. Potassium is completely desorbed, 80% in the first desorption, and then gradually in the following desorptions. Other metals are linked with one weaker link (desorption 1-38% and with one very strong link (desorption below the metal detection limit. [Projekat Ministarstva nauke Republike Srbije, br. III43009 i br. ON 172019

  5. Plasma harmonics

    CERN Document Server

    Ganeev, Rashid A

    2014-01-01

    Preface; Why plasma harmonics? A very brief introduction Early stage of plasma harmonic studies - hopes and frustrations New developments in plasma harmonics studies: first successes Improvements of plasma harmonics; Theoretical basics of plasma harmonics; Basics of HHG Harmonic generation in fullerenes using few-cycle pulsesVarious approaches for description of observed peculiarities of resonant enhancement of a single harmonic in laser plasmaTwo-colour pump resonance-induced enhancement of odd and even harmonics from a tin plasmaCalculations of single harmonic generation from Mn plasma;Low-o

  6. Simple sample transfer technique by internally expanded desorptive flow for needle trap devices.

    Science.gov (United States)

    Eom, In-Yong; Pawliszyn, Janusz

    2008-07-01

    Needle trap devices (NTDs) are improving in simplicity and usefulness for sampling volatile organic compounds (VOCs) since their first introduction in early 2000s. Three different sample transfer methods have been reported for NTDs to date. All methods use thermal desorption and simultaneously provide desorptive flow to transfer desorbed VOCs into a GC separation column. For NTDs having 'side holes', GC carrier gas enters a 'side hole' and passes through sorbent particles to carry desorbed VOCs, while for NTD not having a 'side hole', clean air as desorptive flow can be provided through a needle head by a air tight syringe to sweep out desorbed VOCs or water vapor has been reported recently to be used as desorptive flow. We report here a new simple sample transfer technique for NTDs, in which no side holes and an external desorptive flow are required. When an NTD enriched by a mixture of benzene, toluene, ethylbenzene, and xylene (BTEX) or n-alkane mixture (C6-C15) is exposed to the hot zone of GC injector, the expanding air above the packed sorbent transfers the desorbed compounds from the sorbent to the GC column. This internal air expansion results in clean and sharp desorption profiles for BTEX and n-alkane mixture with no carryover. The effect of desorption temperature, desorption time, and overhead volumes was studied. Decane having vapor pressure of approximately 1 Torr at 20 degrees C showed approximately 1% carryover at the moderate thermal desorption condition (0.5 min at 250 degrees C).

  7. Atom-Scale Reaction Pathways and Free-Energy Landscapes in Oxygen Plasma Etching of Graphene.

    Science.gov (United States)

    Koizumi, Kenichi; Boero, Mauro; Shigeta, Yasuteru; Oshiyama, Atsushi

    2013-05-16

    We report first-principles molecular dynamics calculations combined with rare events sampling techniques that clarify atom-scale mechanisms of oxygen plasma etching of graphene. The obtained reaction pathways and associated free-energy landscapes show that the etching proceeds near vacancies via a two-step mechanism, formation of precursor lactone structures and the subsequent exclusive CO2 desorption. We find that atomic oxygen among the plasma components is most efficient for etching, providing a guidline in tuning the plasma conditions.

  8. 2nd International Workshop on Desorption Induced by Electronic Transitions

    CERN Document Server

    Menzel, Dietrich

    1985-01-01

    The second workshop on Desorption Induced by Electronic Transitions (DIET II) took place October 15-17, 1984, in SchloB Elmau, Bavaria. DIET II, fol­ lowing the great success of DIET I (edited by N. H. Tolk, M. M. Traum, J. C. Tully, T. E. Madey and published in Springer Ser. Chem. Phys. , Vol. 24), again brought together over 60 workers in this exciting field. The "hard co­ re of experts" was essentially the same as in DIET I but the general overlap of participants between the two meetings was small. While DIET I had the function of an exposition of the status of the field DIET II focussed more on new developments. The main emphasis was again on the microscopic under­ standing of DIET but a number of side aspects and the application of DIET ideas to other fields such as sputtering, laser-induced desorption, fractu­ re, erosion, etc. were considered, too. New mechanisms and new refined expe­ rimental techniques were proposed and discussed at the meeting critically but with great enthusiasm. In addition t...

  9. 3rd International Workshop on Desorption Induced by Electronic Transitions

    CERN Document Server

    Knotek, Michael

    1988-01-01

    These proceedings are the result of the third international workshop on Desorption Induced by Electronic Transitions, DIET III, which took place on Shelter Island, NY, May. 20-22, 1987. The work contained in this volume is an excellent summary of the current status of the field and should be a valuable reference text for both "seasoned" researchers and newcomers in the field of DIET. Based on the success of the meeting it seems clear that interest and enthusiasm in the field is strong. It is also apparent, from the many lively discussions during the meeting, that many unanswered questions (and controversies) remain to be solved. It was particularly pleasing to see many new participants from new and rapidly advancing fields, ranging from gas phase dynamics to semiconductor processing. The resulting cross-fertilization from these separate but related fields is playing an important role in helping us understand desorption processes at solid surfaces. In general, the topics covered during the course of the worksh...

  10. 5th International Workshop on Desorption Induced by Electronic Transitions

    CERN Document Server

    Jennison, Dwight R; Stechel, Ellen B; DIET V; Desorption induced by electronic transitions

    1993-01-01

    This volume in the Springer Series on Surface Sciences presents a recent account of advances in the ever-broadening field of electron-and photon-stimulated sur­ face processes. As in previous volumes, these advances are presented as the proceedings of the International Workshop on Desorption Induced by Electronic Transitions; the fifth workshop (DIET V) was held in Taos, New Mexico, April 1-4, 1992. It will be abundantly clear to the reader that "DIET" is not restricted to desorption, but has for several years included photochemistry, non-thermal surface modification, exciton self-trapping, and many other phenomena that are induced by electron or photon bombardment. However, most stimulated surface processes do share a common physics: initial electronic excitation, localization of the excitation, and conversion of electronic energy into nuclear kinetic energy. It is the rich variation of this theme which makes the field so interesting and fruitful. We have divided the book into eleven parts in orde...

  11. The cooling effect by adsorption-desorption cycles

    Directory of Open Access Journals (Sweden)

    Wolak Eliza

    2017-01-01

    Full Text Available Adsorption appliances may turn out to be an alternative to compression-type refrigerators. The adsorption refrigeration machine may be driven by a low-grade heat source, especially solar energy. Solar adsorption cooling systems are environment-friendly and have zero ozone depletion potential. Therefore, the adsorption refrigeration is one kind of energy saving refrigeration methods. The merits of the adsorption refrigeration systems will be more significant especially when it is used in vehicles (automobiles, ships and locomotives, to preserve food and medicines and in air-conditioning. The paper presents the advantages and disadvantages as well as the evolution of the technology of adsorptive refrigeration systems. The methods of improving of adsorption refrigeration systems through improvements in adsorbents properties, use of advanced cycles and hybrid systems is also presented. Possible applications and perspectives for development of adsorption cooling systems are also analyzed. The paper describes a test stand of the adsorption-desorption refrigeration. The present investigations have been carried out utilizing the activated carbon granules as an adsorbent and methanol as an adsorbate. The paper demonstrates the measurement of temperature changes in the adsorbent bed and condenser during adsorption-desorption cycles.

  12. Wheat Growth in Soils Treated by Ex Situ Thermal Desorption.

    Science.gov (United States)

    O'Brien, Peter L; DeSutter, Thomas M; Casey, Francis X M; Wick, Abbey F; Khan, E

    2017-07-01

    Successful remediation of oil-contaminated agricultural land may include the goal of returning the land to prespill levels of agricultural productivity. This productivity may be measured by crop yield, quality, and safety, all of which are influenced by soil characteristics. This research was conducted to determine if these metrics are affected in hard red spring wheat ( L. cultivar Barlow) when grown in soils treated by ex situ thermal desorption (TD) compared with wheat grown in native topsoil (TS). Additionally, TD soils were mixed with TS at various ratios to assess the effectiveness of soil mixing as a procedure for enhancing productivity. In two greenhouse studies, TD soils alone produced similar amounts of grain and biomass as TS, although grain protein in TD soils was 22% (±7%) lower. After mixing TS into TD soils, the mean biomass and grain yield were reduced by up to 60%, but grain protein increased. These trends are likely the result of nutrient availability determined by soil organic matter and nutrient cycling performed by soil microorganisms. Thermal desorption soil had 84% (±2%) lower soil organic carbon than TS, and cumulative respiration was greatly reduced (66 ± 2%). From a food safety perspective, grain from TD soils did not show increased uptake of polycyclic aromatic hydrocarbons. Overall, this research suggests that TD soils are capable of producing safe, high-quality grain yields. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  13. Thermally assisted desorption processes in electron bombarded alkali halides

    Energy Technology Data Exchange (ETDEWEB)

    Kolodziej, J.; Czuba, P.; Piatkowski, P.; Postawa, Z.; Kempter, V.; Szymonski, M. (Uniwersytet Jagiellonski, Cracow (Poland). Inst. Fizyki)

    The desorption of alkali and halogen atoms induced by the interaction of energetic electrons with surfaces of alkali halide crystals has been studied by means of an angular-resolved and mass-selected time-of-flight spectroscopy. It has been found that a considerable fraction of halogen atoms was ejected with hyperthermal energies of the order of 0.1 eV. However, alkali atoms and the remaining part of halogen emission had thermal (Maxwellian) spectra of kinetic energies. In this paper we will report on systematic investigations of these thermal desorption processes for single crystal (100) NaCl, KCl, KBr, RbBr, and Kl surfaces. The relative yield of the thermal component has been measured as a function of electron beam energy and beam current density at various sample temperatures. It will be shown that thermal halogen emission can be explained by thermally assisted diffusion of interstitial halogen atoms produced in the bulk of the crystal from decaying self-trapped excitons. The origin of the alkali atom component will be described as due to neutralization and subsequent thermal evaporation of excess alkali atoms from the halogen deficient surface. (Author).

  14. Laser desorption postionization for imaging MS of biological material.

    Science.gov (United States)

    Akhmetov, Artem; Moore, Jerry F; Gasper, Gerald L; Koin, Peter J; Hanley, Luke

    2010-02-01

    Vacuum ultraviolet single photon ionization (VUV SPI) is a soft ionization technique that has the potential to address many of the limitations of matrix-assisted laser desorption/ionization (MALDI) for imaging MS. Laser desorption postionization (LDPI) uses VUV SPI for postionization and is experimentally analogous to a MALDI instrument with the addition of a pulsed VUV light source. This review discusses progress in LDPI-MS over the last decade, with an emphasis on imaging MS of bacterial biofilms, analytes whose high salt environment make them particularly resistant to imaging by MALDI-MS. This review first considers fundamental aspects of VUV SPI including ionization mechanisms, cross sections, quantum yields of ionization, dissociation and potential mass limits. The most common sources of pulsed VUV radiation are then described along with a newly constructed LDPI-MS instrument with imaging capabilities. Next, the detection and imaging of small molecules within intact biofilms is demonstrated by LDPI-MS using 7.87 eV (157.6 nm) VUV photons from a molecular fluorine excimer laser, followed by the use of aromatic tags for detection of selected species within the biofilm. The final section considers the future prospects for imaging intact biological samples by LDPI-MS. Copyright 2010 John Wiley & Sons, Ltd.

  15. Laser desorption VUV postionization MS imaging of a cocultured biofilm.

    Science.gov (United States)

    Bhardwaj, Chhavi; Moore, Jerry F; Cui, Yang; Gasper, Gerald L; Bernstein, Hans C; Carlson, Ross P; Hanley, Luke

    2013-09-01

    Laser desorption postionization mass spectrometry (LDPI-MS) imaging is demonstrated with a 10.5 eV photon energy source for analysis and imaging of small endogenous molecules within intact biofilms. Biofilm consortia comprised of a synthetic Escherichia coli K12 coculture engineered for syntrophic metabolite exchange are grown on membranes and then used to test LDPI-MS analysis and imaging. Both E. coli strains displayed many similar peaks in LDPI-MS up to m/z 650, although some observed differences in peak intensities were consistent with the appearance of byproducts preferentially expressed by one strain. The relatively low mass resolution and accuracy of this specific LDPI-MS instrument prevented definitive assignment of species to peaks, but strategies are discussed to overcome this shortcoming. The results are also discussed in terms of desorption and ionization issues related to the use of 10.5 eV single-photon ionization, with control experiments providing additional mechanistic information. Finally, 10.5 eV LDPI-MS was able to collect ion images from intact, electrically insulating biofilms at ~100 μm spatial resolution. Spatial resolution of ~20 μm was possible, although a relatively long acquisition time resulted from the 10 Hz repetition rate of the single-photon ionization source.

  16. Desorption of alkali atoms from 4He nanodroplets.

    Science.gov (United States)

    Hernando, Alberto; Barranco, Manuel; Pi, Martí; Loginov, Evgeniy; Langlet, Marina; Drabbels, Marcel

    2012-03-21

    The dynamics following the photoexcitation of Na and Li atoms located on the surface of helium nanodroplets has been investigated in a joint experimental and theoretical study. Photoelectron spectroscopy has revealed that excitation of the alkali atoms via the (n + 1)s ←ns transition leads to the desorption of these atoms. The mean kinetic energy of the desorbed atoms, as determined by ion imaging, shows a linear dependence on excitation frequency. These experimental findings are analyzed within a three-dimensional, time-dependent density functional approach for the helium droplet combined with a Bohmian dynamics description of the desorbing atom. This hybrid method reproduces well the key experimental observables. The dependence of the observables on the impurity mass is discussed by comparing the results obtained for the (6)Li and (7)Li isotopes. The calculations show that the desorption of the excited alkali atom is accompanied by the creation of highly non-linear density waves in the helium droplet that propagate at supersonic velocities.

  17. Sorption and desorption of dyes by sulfonated coal

    Energy Technology Data Exchange (ETDEWEB)

    Mittal, A.K. (Motilal Nehru Regional Coll. of Engineering, Allahabad (India)); Venkobachar, C. (Indian Inst. of Tech., Kanpur (India))

    Wastewaters from dye-manufacturing factories and textile, paper, and pulp industries are highly colored. Their discharge into river waters make the water inhibitory to aquatic life, aside from causing, visible pollution. Dyes have a tendency to sequester metals, thus causing microtoxicity to fish and other aquatic organisms. A wide variety of low-cost materials such as flyash, clay minerals, coal, tire chippings, coconut shell powder and biosorbents are being tried as viable substitutes for activated carbon to remove different pollutants such as pesticides, heavy metals, and dyes. The removal of dyes depends upon their physical and chemical characteristics, as well as the properties of the selected sorbents. To understand the nature of the chemical bonding between dyes and sorbents during the sorption process, it is essential to conduct desorption studies. The reversibility of adsorption of dyes can also be determined by a simple mathematical equation. These studies provide information on whether or not the sorbent material can be regenerated after exhaustion. The present study focuses on sorption-desorption of dyes by sulfonated coal, whose dye sorption potential was established by Mittal and Venkobachar (1990).

  18. Adsorption and desorption on coals for CO2 sequestration

    Institute of Scientific and Technical Information of China (English)

    WANG Zuo-tang; FU Zhen-kun; ZHANG Ban-gan; WANG Guo-xiong; RUDOLPH Victor; HUO Li-wen

    2009-01-01

    Adsorption and desorption of carbon dioxide, methane and other gases on coals has been investigated experimentally using representative Zhongliangshan coals. Gas adsorption is one of the major concerns for both CO2 sequestration and methane recovery processes. The experiments were carried out using both single and multi-component mixtures at 25 ℃ and 30 ℃ with the highest pressure of 12 MPa. The coal was under moisture equilibrated conditions. This provides experimental data from which a predictive assessment of CO2 sequestration and/or methane recovery can be conducted. The results show that for pure gasses the CH4 adsorption capacity is higher than the N2 adsorption capacity but lower than the CO2 adsorption capacity. Injection of CO2 or other gases into the coal significantly affects CH4 desorption. This allows the enhancement of CH4 recovery from the coals, thus supplying more clean energy while sequestering significant amounts of CO2 thereby reducing the greenhouse effect from human beings.

  19. Thermal desorption of PCBs from contaminated soil with copper dichloride.

    Science.gov (United States)

    Liu, Jie; Qi, Zhifu; Li, Xiaodong; Chen, Tong; Buekens, Alfons; Yan, Jianhua; Ni, Mingjiang

    2015-12-01

    Copper dichloride is an important catalyst both in the dechlorination of chlorinated aromatic compounds and the formation of PCDD/Fs. The effect of copper dichloride on polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) was studied in treated soil and off gas after thermal desorption of PCB-contaminated soil at 300, 400, 500, 600 °C. The presence of copper dichloride clearly enhances thermal desorption by promoting PCBs removal, destruction, and dechlorination. After thermal treatment at 600 °C for 1 h, the removal efficiency and destruction efficiency for PCBs reached 98.1 and 93.9%, respectively. Compared with the positive influence on PCBs, copper dichloride catalyzed large amount of PCDFs formation at 300 °C, with the concentration ratio of 2.35. The effect of CuCl2 on PCDFs formation weakened with the rising temperature since PCDFs destruction became dominant under higher temperature. Different from PCDFs, PCDDs concentration in treated soil and off gas decreased continuously with the increasing temperature.

  20. Magnesium growth in magnesium deuteride thin films during deuterium desorption

    Energy Technology Data Exchange (ETDEWEB)

    Checchetto, R., E-mail: riccardo.checchetto@unitn.it [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Miotello, A. [Dipartimento di Fisica and CNISM, Università di Trento, Via Sommarive 14, I-38123 Trento (Italy); Mengucci, P.; Barucca, G. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Università Politecnica delle Marche, I-60131 Ancona (Italy)

    2013-12-15

    Highlights: ► Highly oriented Pd-capped magnesium deuteride thin films. ► The MgD{sub 2} dissociation was studied at temperatures not exceeding 100 °C. ► The structure of the film samples was analyzed by XRD and TEM. ► The transformation is controlled by the re-growth velocity of the Mg layers. ► The transformation is thermally activated, activation energy value of 1.3 ± 0.1 eV. -- Abstract: Pd- capped nanocrystalline magnesium thin films having columnar structure were deposited on Si substrate by e-gun deposition and submitted to thermal annealing in D{sub 2} atmosphere to promote the metal to deuteride phase transformation. The kinetics of the reverse deuteride to metal transformation was studied by Thermal Desorption Spectroscopy (TDS) while the structure of the as deposited and transformed samples was analyzed by X-rays diffraction and Transmission Electron Microscopy (TEM). In Pd- capped MgD{sub 2} thin films the deuteride to metal transformation begins at the interface between un-reacted Mg and transformed MgD{sub 2} layers. The D{sub 2} desorption kinetics is controlled by MgD{sub 2}/Mg interface effects, specifically the re-growth velocity of the Mg layers. The Mg re-growth has thermally activated character and shows an activation energy value of 1.3 ± 0.1 eV.

  1. Direct Analysis of Gold Nanoparticles from Dried Droplets Using Substrate-Assisted Laser Desorption Single Particle-ICPMS.

    Science.gov (United States)

    Benešová, Iva; Dlabková, Kristýna; Zelenák, František; Vaculovič, Tomáš; Kanický, Viktor; Preisler, Jan

    2016-03-01

    Single particle inductively coupled plasma mass spectrometry (SP-ICPMS) has been generally accepted as a powerful tool in the field of nanoanalysis. The method has usually been restricted to direct nanoparticle (NP) introduction using nebulization or microdroplet generation systems. In this work, AuNPs are introduced into ICPMS by substrate-assisted laser desorption (SALD) directly from a suitable absorbing plastic surface using a commercial ablation cell for the first time. In SALD, desorption of individual NPs is mediated using a frequency-quintupled Nd:YAG laser (213 nm) operated at a rather low laser fluence. Conditions including laser fluence, laser beam scan rate, and carrier gas flow rate were optimized in order to gain the highest AuNP transport efficiency and avoid AuNP disintegration within the laser irradiation. The method was demonstrated on a well-characterized reference material, 56 nm AuNPs with a transport efficiency of 61% and commercially available 86 nm AuNPs. Feasibility of our technique for NP detection and characterization is discussed here, and the results are compared with an established technique, nebulizer SP-ICPMS.

  2. Auger decay mechanism in photon-stimulated desorption of ions from surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Parks, C.C.

    1983-11-01

    Photon-stimulated desorption (PSD) of positive ions was studied with synchrotron radiation using an angle-integrating time-of-flight mass spectrometer. Ion yields as functions of photon energy near core levels were measured from condensed gases, alkali fluorides, and other alkali and alkaline earth halides. These results are compared to bulk photoabsorption measurements with emphasis on understanding fundamental desorption mechanisms. The applicability of the Auger decay mechanism, in which ion desorption is strictly proportional to surface absorption, is discussed in detail. The Auger decay model is developed in detail to describe Na/sup +/ and F/sup +/ desorption from NaF following Na(1s) excitation. The major decay pathways of the Na(1s) hole leading to desorption are described and equations for the energetics of ion desorption are developed. Ion desorption spectra of H/sup +/, Li/sup +/, and F/sup +/ are compared to bulk photoabsorption near the F(2s) and Li(1s) edges of LiF. A strong photon beam exposure dependence of ion yields from alkali fluorides is revealed, which may indicate the predominance of metal ion desorption from defect sites. The large role of indirect mechanisms in ion desorption condensed N/sub 2/-O/sub 2/ multilayers is demonstrated and discussed. Ion desorption spectra from several alkali halides and alkaline earth halides are compared to bulk photoabsorption spectra. Relative ion yields from BaF/sub 2/ and a series of alkali halides are discussed in terms of desorption mechanisms.

  3. A Combined Desorption Ionization by Charge Exchange (DICE) and Desorption Electrospray Ionization (DESI) Source for Mass Spectrometry

    Science.gov (United States)

    Chan, Chang-Ching; Bolgar, Mark S.; Miller, Scott A.; Attygalle, Athula B.

    2011-01-01

    A source that couples the desorption ionization by charge exchange (DICE) and desorption electrospray ionization (DESI) techniques together was demonstrated to broaden the range of compounds that can be analyzed in a single mass spectrometric experiment under ambient conditions. A tee union was used to mix the spray reagents into a partially immiscible blend before this mixture was passed through a conventional electrospray (ES) probe capillary. Using this technique, compounds that are ionized more efficiently by the DICE method and those that are ionized better with the DESI procedure could be analyzed simultaneously. For example, hydroquinone, which is not detected when subjected to DESI-MS in the positive-ion generation mode, or the sodium adduct of guaifenesin, which is not detected when examined by DICE-MS, could both be detected in one experiment when the two techniques were combined. The combined technique was able to generate the molecular ion, proton and metal adduct from the same compound. When coupled to a tandem mass spectrometer, the combined source enabled the generation of product ion spectra from the molecular ion and the [M + H]+ or [M + metal]+ ions of the same compound without the need to physically change the source from DICE to DESI. The ability to record CID spectra of both the molecular ion and adduct ions in a single mass spectrometric experiment adds a new dimension to the array of mass spectrometric methods available for structural studies.

  4. Feasibility of desorption atmospheric pressure photoionization and desorption electrospray ionization mass spectrometry to monitor urinary steroid metabolites during pregnancy.

    Science.gov (United States)

    Vaikkinen, Anu; Rejšek, Jan; Vrkoslav, Vladimír; Kauppila, Tiina J; Cvačka, Josef; Kostiainen, Risto

    2015-06-23

    Steroids have important roles in the progress of pregnancy, and their study in maternal urine is a non-invasive method to monitor the steroid metabolome and its possible abnormalities. However, the current screening techniques of choice, namely immunoassays and gas and liquid chromatography-mass spectrometry, do not offer means for the rapid and non-targeted multi-analyte studies of large sample sets. In this study, we explore the feasibility of two ambient mass spectrometry methods in steroid fingerprinting. Urine samples from pregnant women were screened by desorption electrospray ionization (DESI) and desorption atmospheric pressure photoionization (DAPPI) Orbitrap high resolution mass spectrometry (HRMS). The urine samples were processed by solid phase extraction for the DESI measurements and by enzymatic hydrolysis and liquid-liquid-extraction for DAPPI. Consequently, steroid glucuronides and sulfates were detected by negative ion mode DESI-HRMS, and free steroids by positive ion mode DAPPI-HRMS. In DESI, signals of eleven steroid metabolite ions were found to increase as the pregnancy proceeded, and in DAPPI ten steroid ions showed at least an order of magnitude increase during pregnancy. In DESI, the increase was seen for ions corresponding to C18 and C21 steroid glucuronides, while DAPPI detected increased excretion of C19 and C21 steroids. Thus both techniques show promise for the steroid marker screening in pregnancy.

  5. Dusty plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Fortov, Vladimir E; Khrapak, Aleksei G; Molotkov, Vladimir I; Petrov, Oleg F [Institute for High Energy Densities, Associated Institute for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation); Khrapak, Sergei A [Max-Planck-Institut fur Extraterrestrische Physik, Garching (Germany)

    2004-05-31

    The properties of dusty plasmas - low-temperature plasmas containing charged macroparticles - are considered. The most important elementary processes in dusty plasmas and the forces acting on dust particles are investigated. The results of experimental and theoretical investigations of different states of strongly nonideal dusty plasmas - crystal-like, liquid-like, gas-like - are summarized. Waves and oscillations in dusty plasmas, as well as their damping and instability mechanisms, are studied. Some results on dusty plasma investigated under microgravity conditions are presented. New directions of experimental research and potential applications of dusty plasmas are discussed. (reviews of topical problems)

  6. Determination of anticonvulsants in human plasma using SPME in a heated interface coupled online to liquid chromatography (SPME-LC)

    OpenAIRE

    Alves, Claudete; Gomes, Paulo Clairmont Feitosa de Lima; Neto, Álvaro José dos Santos; Rodrigues, Jose Carlos; Lanças, Fernando Mauro

    2012-01-01

    A simple and sensitive method using solid phase microextraction (SPME) and liquid chromatography (LC) with heated online desorption (SPME-LC) was developed and validated to analyze anticonvulsants (AEDs) in human plasma samples. A heated lab-made interface chamber was used in the desorption procedure, which allowed the transference of the whole extracted sample. The SPME conditions were optimized by applying an experimental design. Important factors are discussed such as fiber coating types, ...

  7. Electronically driven adsorbate excitation mechanism in femtosecond-pulse laser desorption

    DEFF Research Database (Denmark)

    Brandbyge, Mads; Hedegård, Per; Heinz, T. F.

    1995-01-01

    Femtosecond-pulse laser desorption is a process in which desorption is driven by a subpicosecond temperature pulse of order 5000 K in the substrate-adsorbate electron system, whose energy is transferred into the adsorbate center-of-mass degrees of freedom by a direct coupling mechanism. We presen...

  8. Desorption of two organophosphorous pesticides from soil with wastewater and surfactant solutions.

    Science.gov (United States)

    Hernández-Soriano, M C; Mingorance, M D; Peña, A

    2012-03-01

    A batch test was used to evaluate the extent of desorption of diazinon and dimethoate, preadsorbed on a calcareous agricultural soil, representative of the Mediterranean area. Urban wastewater from a secondary treatment and seven surfactant solutions, at concentrations ranging from 0.75 mg L(-1) to 10 gL(-1), were used. The surfactants assayed were cationic (hexadecyl trimethyl ammonium bromide (HD)), anionic (sodium dodecyl sulfate (SDS), Aerosol 22 (A22) and Biopower (BP)), and nonionic (Tween 80 (TW), Triton X 100 (TX) and Glucopon 600 (G600)). Desorption of dimethoate was either not affected or only slightly by the nonionic and anionic surfactants tested, while desorption of diazinon from the soil was only enhanced by A22, BP and TW. This desorption increase correlated significantly with the surfactant concentration of the solution used for desorption and with the concurrent increase in the supernatant of the dissolved organic carbon, in particular that originating from the surfactant. This parameter did not vary with the use of SDS, G600 and TX. The cationic surfactant HD was retained on the soil surface, as confirmed by an increase in soil organic carbon, resulting in a fall in desorption rate for both pesticides. Comparing treatment by wastewater with control water, there was no difference in desorption rate for either pesticide. Mixed TW/anionic surfactant solutions either did not modify or slightly increased desorption of both pesticides in comparison with individual surfactant solutions.

  9. [Effects of soil compositions on sorption and desorption behavior of tetrachloroethylene in soil].

    Science.gov (United States)

    Hu, Lin; Qiu, Zhao-Fu; He, Long; Dou, Ying; Lü, Shu-Guang; Sui, Qian; Lin, Kuang-Fei

    2013-12-01

    Sorption and desorption play an important role in the transport and the fate of tetrachloroethylene (PCE) in soil. In order to examine influences of different soil compositions on PCE sorption-desorption, equilibrium batch experiments were carried out using four sorbents (natural soil with 2.23% total organic carbon (TOC), H2O2-treated soil, 375 degrees C-treated soil and 600 degrees C-treated soil) with different initial PCE liquid concentrations (c0). The effects of main parameters (TOC, soft carbon, hard carbon, minerals, c0) on PCE sorption-desorption were investigated. At 16 degrees C, when c0 was increased from 5 to 80 mg x L(-1), the results showed that sorption and desorption isotherms of PCE on four sorbents can be best described by the Freundlich model (r2 > 0.96). The sorption contribution rate of SOM was higher than 60% in natural soil, and hard carbon was the main influencing factor,while the desorption contribution rate of SOM was close to that of minerals in natural soil, and soft carbon accounted for more than 80% in the total desorption contribution rate of SOM. In addition, the higher the c0, the higher the sorption contribution rate of PCE in hard carbon and desorption contribution rate of PCE in soft carbon and minerals were. Moreover, desorption of PCE from four sorbents exhibited hysteresis, and hard carbon played a remarkable role in the hysteresis of natural soil.

  10. Thermal desorption of deuterium from modified carbon nanotubes and its correlation to the microstructure

    NARCIS (Netherlands)

    Lisowski, W.; Keim, E.G.; Berg, van den A.H.J.; Smithers, M.A.

    2006-01-01

    The process of deuterium desorption from single-wall carbon nanotubes (SWNTs) modified by atomic (D) and molecular (D2) deuterium treatment was investigated in an ultrahigh vacuum environment using thermal desorption mass spectroscopy (TDMS). Microstructural and chemical analyses of SWNT material, m

  11. Kinetic characteristics of coal gas desorption based on the pulsating injection

    Institute of Scientific and Technical Information of China (English)

    Ni Guanhua; Lin Baiquan; Zhai Cheng; Li Quangui; Peng Shen; Li Xianzhong

    2014-01-01

    In order to understand the kinetic characteristics of coal gas desorption based on the pulsating injection (PI), the research experimentally studied the kinetic process of methane desorption in terms of the PI and hydrostatic injection (HI). The results show that the kinetic curves of methane desorption based on PI and HI are consistent with each other, and the diffusion model can best describe the characteristics of meth-ane desorption. Initial velocity, diffusion capacity and ultimate desorption amount of methane desorption after PI are greater than those after HI, and the ultimate desorption amount increases by 16.7-39.7%. Methane decay rate over the time is less than that of the HI. The PI influences the diffusion model param-eters, and it makes the mass transfer Biot number B0i decrease and the mass transfer Fourier series F00 increase. As a result, PI makes the methane diffusion resistance in the coal smaller, methane diffusion rate greater, mass transfer velocity faster and the disturbance range of methane concentration wider than HI. Therefore, the effect of methane desorption based on PI is better than that of HI.

  12. Hypotonic elution, a new desorption principle in immunoadsorbent chromatography

    DEFF Research Database (Denmark)

    Danielsen, Erik Michael; Sjöström, H; Norén, O

    1982-01-01

    of finding an efficient means of elution which is not denaturing to neither the purified enzyme nor the immunoadsorbent column. Common properties of the microvillar enzymes with regard to amphiphilicity, glycosylation or subunit composition could hypothetically account for the similar elution properties......A largely unrecognized immunoadsorbent desorption technique, hypotonic elution, has been successfully used in the immunoadsorbent purification of the microvillar enzymes aminopeptidase N (EC 3.4.11.2), dipeptidyl peptidase IV (EC 3.4.14.5), sucrase-isomaltase (EC 3.2.1.48-10), lactase......-phlorizin hydrolase (EC 3.2.1.23-62) and maltase-glucoamylase (EC 3.2.1.20). This elution method proved capable of achieving an acceptable yield (30-70%) while at the same time preserving the purified enzymes in an enzymically active state. It hereby offers a solution to the problem in immunoadsorbent chromatography...

  13. Thermal desorption of CH4 retained in CO2 ice

    CERN Document Server

    Luna, R; Domingo, M; Satorre, M A

    2008-01-01

    CO2 ices are known to exist in different astrophysical environments. In spite of this, its physical properties (structure, density, refractive index) have not been as widely studied as those of water ice. It would be of great value to study the adsorption properties of this ice in conditions related to astrophysical environments. In this paper, we explore the possibility that CO2 traps relevant molecules in astrophysical environments at temperatures higher than expected from their characteristic sublimation point. To fulfil this aim we have carried out desorption experiments under High Vacuum conditions based on a Quartz Crystal Microbalance and additionally monitored with a Quadrupole Mass Spectrometer. From our results, the presence of CH4 in the solid phase above the sublimation temperature in some astrophysical scenarios could be explained by the presence of several retaining mechanisms related to the structure of CO2 ice.

  14. Apparatus for low temperature thermal desorption spectroscopy of portable samples

    Science.gov (United States)

    Stuckenholz, S.; Büchner, C.; Ronneburg, H.; Thielsch, G.; Heyde, M.; Freund, H.-J.

    2016-04-01

    An experimental setup for low temperature thermal desorption spectroscopy (TDS) integrated in an ultrahigh vacuum-chamber housing a high-end scanning probe microscope for comprehensive multi-tool surface science analysis is described. This setup enables the characterization with TDS at low temperatures (T > 22 K) of portable sample designs, as is the case for scanning probe optimized setups or high-throughput experiments. This combination of techniques allows a direct correlation between surface morphology, local spectroscopy, and reactivity of model catalysts. The performance of the multi-tool setup is illustrated by measurements of a model catalyst. TDS of CO from Mo(001) and from Mo(001) supported MgO thin films were carried out and combined with scanning tunneling microscopy measurements.

  15. Solvent desorption dynamic headspace sampling of fermented dairy product volatiles.

    Science.gov (United States)

    Rankin, S A

    2001-01-01

    A method was developed based on solvent desorption dynamic headspace analysis for the identification and relative quantification of volatiles significant to the study of fermented dairy product aroma. Descriptions of applications of this method are presented including the measurement of diacetyl and acetoin in fermented milk, the evaluation of volatile-hydrocolloid interactions in dairy-based matrices, and the identification of volatiles in cheeses for canonical discriminative analysis. Advantages of this method include rapid analysis, minimal equipment investment, and the ability to analyze samples with traditional GC split/splitless inlet systems. Limitations of this method are that the sample must be in the liquid state and the inherent analytical limitation to those compounds that do not coelute with the solvent or solvent impurity peaks.

  16. Study of Thermal Desorption of Helium from Hydrogenated Zirconium

    Institute of Scientific and Technical Information of China (English)

    SUN Wei-Ming; WEI Yu-Cheng; SHI Li-Qun

    2006-01-01

    @@ A new method prepared for helium and hydrogen co-containing Zr films is presented to simulate aging metal tritides, in which direct current magnetron sputtering with a He/H/Ar mixture is used. The retained amount and depth profiles of helium and hydrogen are determined by elastic recoil detection analysis. Thermal desorption spectrometry is applied to investigate He thermal release and the effect of hydrogen. It is found that the hightemperature peaks with a large mount of helium release obviously shifted toward lower temperature at high hydrogen concentration, especially at the hydride transformation region, and that the shapes of the release peaks also changed due to the additional hydrogen. However, at the low-temperature releasing region the peak intense decreases when phase transformation takes place. The mechanism of helium thermal release and the effect of hydrogen are also discussed.

  17. Desorption of radioactive cesium by seawater from the suspended particles in river water.

    Science.gov (United States)

    Onodera, Masaki; Kirishima, Akira; Nagao, Seiya; Takamiya, Kouichi; Ohtsuki, Tsutomu; Akiyama, Daisuke; Sato, Nobuaki

    2017-10-01

    In 2011, the accident at the Fukushima-Daiichi nuclear power plant dispersed radioactive cesium throughout the environment, contaminating the land, rivers, and sea. Suspended particles containing clay minerals are the transportation medium for radioactive cesium from rivers to the ocean because cesium is strongly adsorbed between the layers of clay minerals, forming inner sphere complexes. In this study, the adsorption and desorption behaviors of radioactive cesium from suspended clay particles in river water have been investigated. The radioactive cesium adsorption and desorption experiments were performed with two kinds of suspended particulate using a batch method with (137)Cs tracers. In the cesium adsorption treatment performed before the desorption experiments, simulated river water having a total cesium concentration ([(133+137)Cs(+)]total) of 1.3 nM (10(-9) mol/L) was used. The desorption experiments were mainly conducted at a solid-to-liquid ratio of 0.17 g/L. The desorption agents were natural seawater collected at 10 km north of the Fukushima-Daiichi nuclear power plant, artificial seawater, solutions of NaCl, KCl, NH4Cl, and (133)CsCl, and ultrapure water. The desorption behavior, which depends on the preloaded cesium concentration in the suspended particles, was also investigated. Based on the cesium desorption experiments using suspended particles, which contained about 1000 ng/g loaded cesium, the order of cesium desorption ratios for each desorption agent was determined as 1 M NaCl (80%) > 470 mM NaCl (65%) > 1 M KCl (30%) ≈ seawater (natural seawater and Daigo artificial seawater) > 1 M NH4Cl (20%) > 1 M (133)CsCl (15%) ≫ ultrapure water (2%). Moreover, an interesting result was obtained: The desorption ratio in the 470 mM NaCl solution was much higher than that in seawater, even though the Na(+) concentrations were identical. These results indicate that the cesium desorption mechanism is not a simple ion exchange reaction

  18. Experimental study of water effects on gas desorption during high-pressure water injection

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-hua; LIU Xian-xin; BI Ye-wu; PU Wen-long

    2011-01-01

    For the question of applying high-pressure water injection to increase gas extraction efficiency by increasing the permeability of water to drive gas action,an independently designed gas desorption experimental measuring device was used under the condition of external solution invasion.The law of water effect on gas desorption was obtained after water invasion through experiment for the first time.The results show that water's later invasion not only can make the quantity of gas desorption greatly reduced,but also can make gas desorption end early.Therefore,when evaluating the applications of high-pressure water injection to increase gas extraction efficiency,we should take water damaging effects on gas desorption into account.

  19. Bonding configurations for nickelocene on Ag(100) and steric effects in thermal desorption

    Energy Technology Data Exchange (ETDEWEB)

    Borca, C.N.; Welipitiya, D.; Dowben, P.A.; Boag, N.M.

    2000-02-10

    The molecular adsorption and desorption of nickelocene, Ni(C{sub 5}H{sub 5}){sub 2}, on Ag(100) has been studied by coverage dependent angle-resolved thermal desorption. The angle-resolved thermal desorption of nickelocene is unusual in that the molecular orientation is seen to affect the angular dependence of molecular desorption. The coexistence of two chemisorption phases for molecular nickelocene adsorption on Ag(100) near the desorption temperature of approximately 230 K is identified. One phase, with the bonding configuration of the nickelocene molecular axis along the surface normal, appears to dominate at higher coverages. The results are discussed in the context of rehybridization and recent angle-resolved photoemission and high-resolution electron energy loss measurements.

  20. Hydrogen desorption in nanocrystalline MgH{sub 2} thin films at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ares, J.R., E-mail: joser.ares@uam.e [Dpto. de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049, Madrid (Spain); Leardini, F.; Diaz-Chao, P.; Bodega, J. [Dpto. de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049, Madrid (Spain); Koon, D.W. [Physics Department, St Lawrence University, Canton, NY, 13617 (United States); Ferrer, I.J.; Fernandez, J.F.; Sanchez, C. [Dpto. de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049, Madrid (Spain)

    2010-04-16

    Hydrogen desorption process of Pd-capped magnesium hydride thin films of different thicknesses was investigated. Decomposition of magnesium hydride into magnesium under air exposure is observed in all investigated films. During decomposition no novel crystalline phases are detected. Desorption process was qualitatively analysed and it was concluded that is thermodynamically driven controlled by a nucleation and growth or by an interphase controlled mechanism. Moreover, H-kinetics investigation of desorption process was carried out by thermal desorption spectroscopy. Decomposition of MgH{sub 2} films occurs at T{sub d} {approx} 148 {sup o}C and the process seems to be controlled by a bidimensional interphase mechanism with an activation energy of 135 {+-} 20 kJ/mol H{sub 2}. No significant influence of thickness and crystallite size on desorption temperature is observed and obtained activation energy is similar to that of milled bulk magnesium.

  1. Orbital dynamics of a solar sail accelerated by thermal desorption of coatings

    CERN Document Server

    Ancona, Elena

    2016-01-01

    In this study we considered a solar sail coated with materials that undergo thermal desorption at a specific temperature, as a result of heating by solar radiation at a particular heliocentric distance. Three different scenarios, that only differ in the way the sail approaches the Sun, were analyzed and compared. In every case once the perihelion is reached, the sail coat undergoes thermal desorption. When the desorption process ends, the sail then escapes the Solar System having the conventional acceleration due to solar radiation pressure. Thermal desorption here comes as an additional source of solar sail acceleration beside traditional propulsion systems for extrasolar space exploration. The compared scenarios are the following: i. Hohmann transfer plus thermal desorption. In this scenario the sail would be carried as a payload to the perihelion with a conventional propulsion system by an Hohmann transfer from Earth's orbit to an orbit very close to the Sun (almost at 0.1 AU) and then be deployed there. i...

  2. Atoms and Nanoparticles of Transition Metals as Catalysts for Hydrogen Desorption from Magnesium Hydride

    Directory of Open Access Journals (Sweden)

    N. Bazzanella

    2011-01-01

    Full Text Available The hydrogen desorption kinetics of composite materials made of magnesium hydride with transition metal additives (TM: Nb, Fe, and Zr was studied by several experimental techniques showing that (i a few TM at.% concentrations catalyse the H2 desorption process, (ii the H2 desorption kinetics results stabilized after a few H2 sorption cycles when TM atoms aggregate by forming nanoclusters; (iii the catalytic process occurs also at TM concentration as low as 0.06 at.% when TM atoms clustering is negligible, and (iv mixed Fe and Zr additives produce faster H2 desorption kinetics than single additive. The improved H2 desorption kinetics of the composite materials can be explained by assuming that the interfaces between the MgH2 matrix and the TM nanoclusters act as heterogeneous sites for the nucleation of the Mg phase in the MgH2 matrix and promote the formation of fast diffusion channels for H migrating atoms.

  3. Decomposition kinetics study of zirconium hydride by interrupted thermal desorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Mingwang; Liang, Li; Tang, Binghua; Xiang, Wei; Wang, Yuan; Cheng, Yanlin; Tan, Xiaohua, E-mail: caepiee@163.com

    2015-10-05

    Highlights: • Interrupted TDS was applied to investigate the mechanism of ZrH{sub 2} decomposition. • The activation energies for the five desorption peaks were determined. • The origins of the five desorption peaks were identified. • The γZrH phase was observed at ambient conditions. - Abstract: Thermal desorption kinetics of zirconium hydride powder were studied using thermogravimetry and simultaneous thermal desorption spectroscopy. The activation energies for observed desorption peaks were estimated according to Kissinger relation. The intermediate phase composition was studied using X-ray diffraction by rapid cooling on different stages of heating. The origins of the peaks were described as the equilibrium hydrogen pressure of a number of consecutive phase regions that decomposition reaction passed through. The zirconium monohydride γZrH was observed for extended periods of time at ambient conditions, which has been supposed to be metastable for a long time.

  4. Adsorption, Diffusion and Thermal Desorption Features of Cyclopentane and Cyclohexane in Silicalite-1

    Institute of Scientific and Technical Information of China (English)

    DUAN, Lin-Hai; SONG, Li-Juan; ZHANG, Xiao-Tong; TANG, Ke; DAI, Zhen-Hua; SUN, Zhao-Lin

    2006-01-01

    Adsorption, diffusion and thermal desorption features of cyclopentane and cyclohexane in silicalite-1 have been investigated using the intelligent gravimetric technique. Both the saturation adsorption loadings and diffusion coefficient of cyclopentane were greater than those of cyclohexane. The diffusivity of cyclopentane was about one order of magnitude greater than that of cyclohexane at the same temperature and initial loading. For cyclopentane, there was only one kind of desorption process at adsorption loadings lower than 4 muc (molecule per unit cell), but two desorption processes appeared at the adsorption loadings higher than 4 muc. While for cyclohexane, one desorption process was found in the whole range of loadings. Both thermal desorption peaks of cyclopentane and cyclohexane moved to higher temperature region with increasing loading.

  5. Sorption, desorption, and surface oxidative fate of nicotine.

    Science.gov (United States)

    Petrick, Lauren; Destaillats, Hugo; Zouev, Irena; Sabach, Sara; Dubowski, Yael

    2010-09-21

    Nicotine dynamics in an indoor environment can be greatly affected by building parameters (e.g. relative humidity (RH), air exchange rate (AER), and presence of ozone), as well as surface parameters (e.g. surface area (SA) and polarity). To better understand the indoor fate of nicotine, these parameter effects on its sorption, desorption, and oxidation rates were investigated on model indoor surfaces that included fabrics, wallboard paper, and wood materials. Nicotine sorption under dry conditions was enhanced by higher SA and higher polarity of the substrate. Interestingly, nicotine sorption to cotton and nylon was facilitated by increased RH, while sorption to polyester was hindered by it. Desorption was affected by RH, AER, and surface type. Heterogeneous nicotine-ozone reaction was investigated by Fourier transform infrared spectrometry with attenuated total reflection (FTIR-ATR), and revealed a pseudo first-order surface reaction rate of 0.035 +/- 0.015 min(-1) (at [O(3)] = 6 +/- 0.3 x 10(15) molecules cm(-3)) that was partially inhibited at high RH. Extrapolation to a lower ozone level ([O(3)] = 42 ppb) showed oxidation on the order of 10(-5) min(-1) corresponding to a half-life of 1 week. In addition, similar surface products were identified in dry and high RH using gas chromatography-mass spectrometry (GC-MS). However, FTIR analysis revealed different product spectra for these conditions, suggesting additional unidentified products and association with surface water. Knowing the indoor fate of condensed and gas phase nicotine and its oxidation products will provide a better understanding of nicotine's impact on personal exposures as well as overall indoor air quality.

  6. Photoabsorption and desorption studies on thiophene-based polymers following sulphur K-shell excitation

    Energy Technology Data Exchange (ETDEWEB)

    Santa Rita, J.R.; Arantes, C.; Araujo, G. [Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro, RJ (Brazil); Roman, L.S. [Departamento de Fisica, Universidade Federal do Parana, 81531-990 Curitiba, PR (Brazil); Micaroni, L. [Departamento de Quimica, Universidade Federal do Parana, 81531-990 Curitiba, PR (Brazil); Rocco, M.L.M., E-mail: luiza@iq.ufrj.br [Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro, RJ (Brazil)

    2011-04-15

    Research highlights: {yields} Photon stimulated ion desorption (PSID) measurements at the S K-shell excitation energies were performed on three thiophene-based polymer films, following their NEXAFS spectra. {yields} For poly(thiophene) (PT) and poly(3-methylthiophene) (P3MT) it was found that the S 1s {yields} {pi}*, {sigma}* (S-C) excitation produces S{sup +} desorption efficiently, showing the importance of the resonant Auger process for breaking the C-S bond. {yields} In the case of poly(3-hexylthiophene) (P3HT) S{sup +} desorption seems to be suppressed due to the orientation of 3-hexyl side-chains on the surface. {yields} Desorption ion yield curves for molecular fragments reproduce the photoabsorption spectrum, indicating that the indirect process is here predominant. - Abstract: Photon stimulated ion desorption (PSID) and NEXAFS studies have been performed on thiophene-based polymers at the Brazilian Synchrotron Light Source following sulphur K-shell photoexcitation. For poly(thiophene) (PT) and poly(3-methylthiophene) (P3MT) it was found that the S 1s {yields} {pi}*, {sigma}{sup *} (S-C) excitation produces S{sup +} desorption efficiently. On the other hand, S{sup 2+} desorption is enhanced at higher energy excitations. These results are interpreted in terms of the Auger-stimulated ion desorption mechanism. For poly(3-hexylthiophene) (P3HT) S{sup +} desorption seems to be suppressed, which may be due to the hexyl side-chains. Desorption ion yield curves for molecular fragments reproduce the photoabsorption spectrum, being dominated by the indirect process.

  7. Phosphorus sorption, desorption and resorption by soils of the Brazilian Cerrado supporting eucalypt

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Nairam F. Filho [Universidade Federal de Santa Maria, Dept. de Ciencia Florestal, Porto Alegre, RS (Brazil); Comerford, N.B. [Florida Univ., Soil and Water Science Dept., Gainesville, FL (United States); Barros, Nairam F. [Universidade Federal de Vicosa, Dept. do Solos, Vicosa, MG (Brazil)

    2005-02-01

    Oxisols of the Brazilian Cerrado are highly weathered phosphorus deficient soils, on which eucalypt is increasingly being grown as a source of carbon and energy for steel manufacturing. Phosphorus (P) fertilization is a necessary practice to assure adequate eucalypt production; therefore, an understanding of cycling by inorganic soil P should lead to efficient P management and more accurate modeling of P bioavailability. Since sorption and desorption reactions control inorganic P bioavailability, the purpose of this study was to contrast P sorption, desorption and subsequent resorption for a range of Cerrado soils. Its specific objectives were to determine (i) if desorption and resorption show the same hysteresis shown by sorption and desorption, (ii) if K{sub d} values of resorption and desorption for Cerrado soils are dependent on the soil's clay content and (iii) if resorption and desorption K{sub d} values are a function of the amount of labile P on the soil surface. Three levels of P were sorbed onto four Cerrado soils with clay contents between 13% and 81%. Phosphorus desorption was measured using anion-exchange membranes. Sorption was a function of soil clay content, and a pedotransfer function for the soil partition coefficient was calculated with an r{sup 2} = 0.99. Desorption and resorption were dependent on both the clay content of the soil (r{sup 2} = 0.59-0.99) and the amount of sorbed labile P. Pedotransfer functions for each of these processes depend on accurate measurement of the inorganic P that responds to disequilibria exchange. Desorption and resorption were not hysteretic; yet desorption was hysteretic with the original sorption isotherm. This suggests the question: how useful are commonly produced sorption isotherms? (Author)

  8. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  9. Plasma astrophysics

    CERN Document Server

    Kaplan, S A; ter Haar, D

    2013-01-01

    Plasma Astrophysics is a translation from the Russian language; the topics discussed are based on lectures given by V.N. Tsytovich at several universities. The book describes the physics of the various phenomena and their mathematical formulation connected with plasma astrophysics. This book also explains the theory of the interaction of fast particles plasma, their radiation activities, as well as the plasma behavior when exposed to a very strong magnetic field. The text describes the nature of collective plasma processes and of plasma turbulence. One author explains the method of elementary

  10. Lowering the desorption temperature of Mg(BH4)2 through doping

    Science.gov (United States)

    Harrison, D.; Thonhauser, T.

    2014-03-01

    Magnesium borohydride Mg(BH4)2 is a very promising hydrogen storage material due to its high gravimetric (14.9 mass%) and volumetric density. However, it is limited for practical storage applications by its high hydrogen desorption temperature of 270°C. Arguments have been made for both high thermodynamic stability and slow kinetics to be responsible for this high desorption temperature. In our study we show that doping of Mg(BH4)2 can address the thermodynamic stability issue and predictably lower its desorption enthalpy. We use ab initio calculations at the DFT level (utilizing vdW-DF) and calculate the change in desorption enthalpy from ground state energy and phonon contributions for several possible hydrogen release reactions. Note that van der Waals interactions are crucial to correctly describe the ground state of this complex hydride. We find that, depending on the reaction, the undoped phase has a desorption enthalpy of 50-75 kJ/mol H2 and doping can lower this number by approximately 5 kJ/mol per 10% doping at 300 K, making the desired range of 40 kJ/mol easily accessible. We argue that this lowering of desorption enthalpy will correspond to a lowering of the desorption temperature. Supported by NSF DMR-1145968.

  11. Photon stimulated desorption of and nuclear resonant scattering by noble gas atoms at solid surfaces

    CERN Document Server

    Ikeda, Akihiko

    2015-01-01

    When a noble gas atom approaches a solid surface, it is adsorbed via the Van der Waals force, which is called physisorption. In this thesis, several experimental results concerning physisorbed atoms at surfaces are presented. First, photon stimulated desorption of Xe atoms from a Au substrate using nano-second laser is presented. With the time-of-flight measurements, the translational temperature and the desorption yield of desorbing Xe as a function of laser fluence are obtained. It is discovered that there are non-thermal and thermal desorption pathways. It is discussed that the former path involves a transient formation of the negative ion of Xe. The desorption flux dependence of the thermal pathway is also investigated. We found that at a large desorption fluxes the desorption flow is thermalized due to the post-desorption collisions. The resultant velocity and the temperature of the flow is found to be in good agreement with the theoretical predictions based on the Knudsen layer formation. Lastly, nuclea...

  12. Plutonium desorption from mineral surfaces at environmental concentrations of hydrogen peroxide.

    Science.gov (United States)

    Begg, James D; Zavarin, Mavrik; Kersting, Annie B

    2014-06-01

    Knowledge of Pu adsorption and desorption behavior on mineral surfaces is crucial for understanding its environmental mobility. Here we demonstrate that environmental concentrations of H2O2 can affect the stability of Pu adsorbed to goethite, montmorillonite, and quartz across a wide range of pH values. In batch experiments where Pu(IV) was adsorbed to goethite for 21 days at pH 4, 6, and 8, the addition of 5-500 μM H2O2 resulted in significant Pu desorption. At pH 6 and 8 this desorption was transient with readsorption of the Pu to goethite within 30 days. At pH 4, no Pu readsorption was observed. Experiments with both quartz and montmorillonite at 5 μM H2O2 desorbed far less Pu than in the goethite experiments highlighting the contribution of Fe redox couples in controlling Pu desorption at low H2O2 concentrations. Plutonium(IV) adsorbed to quartz and subsequently spiked with 500 μM H2O2 resulted in significant desorption of Pu, demonstrating the complexity of the desorption process. Our results provide the first evidence of H2O2-driven desorption of Pu(IV) from mineral surfaces. We suggest that this reaction pathway coupled with environmental levels of hydrogen peroxide may contribute to Pu mobility in the environment.

  13. Effects of methamidophos and glyphosate on copper sorption-desorption behavior in soils

    Institute of Scientific and Technical Information of China (English)

    YU Ying; ZHOU Qixing; HE Zhenli

    2005-01-01

    A batch-equilibration technique was employed to study the impact of two organophosphorus pesticides methamidophos (MDP) and glyphosate (GPS) on copper (Cu2+) sorptiondesorption for phaeozem and burozem collected from Northeastern China. The addition of the two pesticides decreased Cu2+ sorption, increased Cu2+ desorption and prolonged the equilibrium time of Cu2+ sorption-desorption. But GPS appeared to exert a stronger influence on Cu2+ sorption-desorption due to its stronger complexion with Cu2+. When MDP was added, Cu2+ sorption-desorption was linearly correlated with MDP treatment concentrations. But in the presence of GPS, Cu2+ sorption first underwent a rapid decrease period, and then slowly tended towards a steady period. The reverse pattern could be found for Cu2+ desorption in the presence of GPS.Without pesticides and with the existence of MDP, Cu2+ sorption-desorption kinetics was well conformed to two-constant equation and Elovich equation. But that was not the case for Cu2+ desorption kinetics in the presence of GPS although its sorption could be also described by these two equations.

  14. Dynamical Model in Low-Frequency-Pulsed Electron-Stimulated Desorption

    Institute of Scientific and Technical Information of China (English)

    张彤; 吴小山; 胡安; 毛福明; 杨学谦; 崔一平

    2003-01-01

    A dynamical model of low-frequency=pulsed electron=stimulated desorption is developed. The characteristic of desorbed gas flow is taken as an exponential function, and can be degenerated to a triangular and square wave.The transient pressure is given according to the gas flow of desorbing gas and vacuum system parameters,including the pumping speed and the system volume. Although the mathematical model is deduced from the electron-stimulated desorption, it can be applied to other similar processes of intermittent desorption.

  15. A kinetic Monte Carlo study of desorption of H2 from graphite (0001)

    CERN Document Server

    Gavardi, E; Hornekaer, L; 10.1016/j.cplett.2009.07.003

    2009-01-01

    The formation of H2 in the interstellar medium proceeds on the surfaces of silicate or carbonaceous particles. To get a deeper insight of its formation on the latter substrate, this letter focuses on H2 desorption from graphite (0001) in Temperature-Programmed-Desorption Monte-Carlo simulations. The results are compared to experimental results which show two main peaks and an intermediate shoulder for high initial coverage. The simulation program includes barriers obtained by ab-initio methods and is further optimised to match two independent experimental observations. The simulations reproduce the two experimental observed desorption peaks. Additionally, a possible origin of the intermediate peak is given.

  16. Tunable Adsorption and Desorption of Hydrogen Atoms on Single-Walled Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    赵明文; 夏日源; 马玉臣; 英敏菊; 刘向东; 梅良模

    2002-01-01

    Chemical adsorption and desorption of hydrogen atoms on single-walled carbon nanotubes (SWNTs) are investi-gated by using molecular dynamics simulations. It is found that the adsorption and desorption energy of hydrogenatoms depend on the hydrogen coverage and the diameter of the SWNTs. Hydrogen-adsorption geometry at thecoverage of 1.0 is more energetically stable. The adsorption energy decreases with the increasing diameter ofthe armchair tubes. The adsorption and desorption energy of hydrogen atoms can be modified reversibly byexternally radial deformation. The averaged C-H bond energy on the high curvature sites of the deformed tubeincreases with increasing radial deformation, while that on the low curvature sites decreases.

  17. Desorption of H atoms from graphite (0001) using XUV free electron laser pulses

    DEFF Research Database (Denmark)

    Siemer, B.; Olsen, Thomas; Hoger, T.;

    2010-01-01

    , and identifies the highest vibrational state in the adsorbate potential as a major source for the slow atoms. It is evident that multiple electron scattering processes are required for this desorption. A direct electronic excitation of a repulsive hydrogen-carbon bond seems not to be important.......The desorption of neutral H atoms from graphite with femtosecond XUV pulses is reported. The velocity distribution of the atoms peaks at extremely low kinetic energies. A DFT-based electron scattering calculation traces this distribution to desorption out of specific adsorption sites on graphite...

  18. A statistical study on in vivo sorption and desorption of water in ichthyosis vulgaris.

    Science.gov (United States)

    Mukherjee, S; Gupta, A B

    1994-02-01

    Experiments on the variation of electrical conductance on sorption and desorption of water were performed on the skin of 34 subjects: 17 ichthyosis vulgaris patients and 17 normal subjects, matched for age and gender, under different ambient conditions. An exponential model of the form ft = theta oe theta t, where ft denotes fractional conductance at time t, describes the process of desorption with high accuracy. The parameter theta, identifiable as the rate of desorption, is significantly different between the ichthyotic and normal populations. The study discusses the impaired barrier function of the ichthyotic skin.

  19. First-principles calculations of helium and neon desorption from cavities in silicon.

    Science.gov (United States)

    Eddin, A Charaf; Pizzagalli, L

    2012-05-02

    Combining density functional theory, the nudged elastic band technique, and the ultradense fluid model, we investigated the desorption process of He and Ne in silicon. Our results show that the internal surfaces of gas-filled bubbles are not a limiting factor during desorption experiments, since the surface reconstruction opens diffusion paths easier than in the bulk. We show that the vibrational contribution to the energy of helium in the bulk has to be considered in order to determine realistic pressures in the bubbles, when comparing experiments and simulations. At the maximum of desorption, an average pressure of 1-2 GPa is computed.

  20. Equilibrium moisture content (EMC) in Norway spruce during the first and second desorptions

    DEFF Research Database (Denmark)

    Hoffmeyer, Preben; Engelund, Emil Tang; Thygesen, Lisbeth G.

    2011-01-01

    how drying and saturation procedures influence the differences between the 1st and the 2nd desorption curves for Norway spruce (Picea abies (L.) Karst.) sapwood. The study establishes 1st and 2nd desorption isotherms for a variety of initial conditions and it covers the RH range from 60.1% to 99.......9%. The state of the water is not affected by oven-drying and rewetting as demonstrated by time domain low field NMR relaxometry. The results challenge the conclusions of earlier studies and indicate that in these studies the 2nd desorption was initiated at much too low EMC and therefore fails to describe...

  1. Simultaneous effect of dissolved organic carbon, surfactant, and organic acid on the desorption of pesticides investigated by response surface methodology

    DEFF Research Database (Denmark)

    Trinh, Ha Thu; Duong, Hanh Thi; Ta, Thao Thi

    2017-01-01

    Desorption of pesticides (fenobucarb, endosulfan, and dichlorodiphenyltrichloroethane (DDT)) from soil to aqueous solution with the simultaneous presence of dissolved organic carbon (DOC), sodium dodecyl sulfate (SDS), and sodium oxalate (Oxa) was investigated in batch test by applying a full fac...... characteristics of flooding and irrigation water in rice fields, and surfactants from pollution increase the problem with desorption of legacy pesticides in the rice fields....... caused the minimum desorption. This point at conditions of concern for flooding water is high content of organic compounds causing potentially high contamination by desorption, and the remarkably lower desorption at organic matter-free conditions. The suspended organic matter is one of the common...

  2. Kinetics of Surfactant Desorption at an Air–Solution Interface

    KAUST Repository

    Morgan, C. E.

    2012-12-18

    The kinetics of re-equilibration of the anionic surfactant sodium dodecylbenzene sulfonate at the air-solution interface have been studied using neutron reflectivity. The experimental arrangement incorporates a novel flow cell in which the subphase can be exchanged (diluted) using a laminar flow while the surface region remains unaltered. The rate of the re-equilibration is relatively slow and occurs over many tens of minutes, which is comparable with the dilution time scale of approximately 10-30 min. A detailed mathematical model, in which the rate of the desorption is determined by transport through a near-surface diffusion layer into a diluted bulk solution below, is developed and provides a good description of the time-dependent adsorption data. A key parameter of the model is the ratio of the depth of the diffusion layer, H c, to the depth of the fluid, Hf, and we find that this is related to the reduced Péclet number, Pe*, for the system, via Hc/Hf = C/Pe*1/2. Although from a highly idealized experimental arrangement, the results provide an important insight into the "rinse mechanism", which is applicable to a wide variety of domestic and industrial circumstances. © 2012 American Chemical Society.

  3. Quantitative analysis of biopolymers by matrix-assisted laser desorption

    Energy Technology Data Exchange (ETDEWEB)

    Tang, K.; Allman, S.L.; Jones, R.B.; Chen, C.H. (Oak Ridge National Lab., TN (United States))

    1993-08-01

    During the past few years, major efforts have been made to use mass spectrometry to measure biopolymers because of the great potential benefit to biological and medical research. Although the theoretical details of laser desorption and ionization mechanisms of MALDI are not yet fully understood, several models have been presented to explain the production of large biopolymer ions. In brief, it is very difficult to obtain reliable measurements of the absolute quantity of analytes by MALDI. If MALDI is going to become a routine analytical tool, it is obvious that quantitative measurement capability must be pursued. Oligonucleotides and protein samples used in this work were purchased from commercial sources. Nicotinic acid was used as matrix for both types of biopolymers. From this experiment, it is seen that it is difficult to obtain absolute quantitative measurements of biopolymers using MALDI. However, internal calibration with molecules having similar chemical properties can be used to resolve these difficulties. Chemical reactions between biopolymers must be avoided to prevent the destruction of the analyte materials. 10 refs., 8 figs.

  4. Pulsed light desorption of molecular nitrogen from a glass surface

    Science.gov (United States)

    Atutov, S. N.; Danilina, N. A.; Mikerin, S. L.; Plekhanov, A. I.

    2014-03-01

    Experimental results on the pulsed light desorption (PLD) of molecular Nitrogen from the surface of C-52 and Pyrex glasses are presented. The aim of the study was to determine the experimental conditions to obtain the maximum manifestation of the PLD effect of molecular gases. These studies were conducted in vacuum glass cells of different sizes and shapes filled by Nitrogen, whose inner surface was illuminated by the light of a powerful flash lamp. The variation in the density of the desorbed gas in the cell caused by PLD was studied using both a mass spectrometer and a vacuum gauge attached to the illuminated cells. The experimental results are in qualitative agreement with the theoretical model developed. We demonstrates that PLD can drastically increase a peak density of desorbed Nitrogen in a cell and the maximal Nitrogen density can be achieved in a small diameter long cell of cylindrical form. We believe that the results of this experiment can be applied to the loading of some gases inside a hollow-core, photonic band-gap fiber to generate a large optical depth for an experiment in low-light-level nonlinear optics.

  5. Thermal desorption from surfaces with laser-induced defects

    Energy Technology Data Exchange (ETDEWEB)

    Szabelski, Pawel; Panczyk, Tomasz; Rudzinski, Wladyslaw

    2002-12-30

    Monte Carlo simulation method was used to mimic surface damage development caused by short laser pulses. The influence of pulsed laser irradiation on the creation of defect concentration was examined in the case of a model surface. In particular, the dependence of the intact surface area on a number of laser scans was studied and compared with the experimental results obtained for Rh(1 1 1) crystal face. Changes in the adsorptivoperties of the surface produced by laser irradiation are explained with the help of a simple geometric model connecting the laser intensity and the disordered area generated by a single laser shot. It was demonstrated that exponential decay of the Low Energy Electron Diffraction (LEED) signal with the number of laser scans, which is observed experimentally, may result directly from the overlapping of the laser spots created on the surface. This effect becomes enhanced when the laser intensity, hence the spot size, increases. The importance of laser-induced defects in the kinetics of catalytic/separation processes was examined in the case of temperature programmed desorption (TPD) spectra from surfaces subjected to a different number of laser shots. The spectra were simulated by employing the Monte Carlo method as well as by application of the absolute rate theory (ART) coupled with the mean field approximation. The results obtained with both methods were in a good agreement even when weak lateral interactions in the adsorbed phase were allowed.

  6. Prompt Gas Desorption Due to Ion Impact on Accelerator Structures

    Science.gov (United States)

    Vijay, Sagar; Seidl, Peter A.; Faltens, Andy; Lidia, Steven M.

    2011-10-01

    The repetition rate and peak current of high intensity ion accelerators for inertial fusion or other applications may be limited under certain conditions by the desorption of gas molecules and atoms due to stray ions striking the accelerator structure. We have measured the prompt yield of atoms in close proximity to the point of impact of the ions on a surface. Using the 300-keV, K+ ion beam of the Neutralized Drift Compression Experiment (NDCX-I), ions strike a metal target in a 5-10 microsecond bunch. The collector of a Bayert-Alpert style ionization gauge is used to detect the local pressure burst several centimeters away. Pressure transients are observed on a micro-second time scale due to the initial burst of desorbed gas, and on a much longer (~1 second) timescale, corresponding to the equilibration of the pressure after many ``bounces'' of atoms in the vacuum chamber. We report on these time dependent pressure measurements, modeling of the pressure transient, and implications for high-intensity ion accelerators. Work performed under auspices of U.S. DOE by LBNL under Contract DE-AC02-05CH1123.

  7. A combined whelk watch suggests repeated TBT desorption pulses.

    Science.gov (United States)

    Ruiz, J M; Albaina, N; Carro, B; Barreiro, R

    2015-01-01

    Environmental quality in coastal Europe has improved since the complete 2003 ban on the use of tributyltin (TBT) in antifouling paints. However, there is evidence that TBT is entering the water column, presumably from illegal practices. We determined the concentration of butyltins (BTs: TBT and derivatives) in populations of two gastropods, the rock snail Nucella lapillus (n=17) and the mud snail Nassarius reticulatus (n=18) at regular intervals from pre-ban times until 2009 and 2011, respectively, in NW Spain. Although a substantial decline in TBT occurred shortly after the ban, no significant changes were observed in either species over the last 3-year period of study. In addition, the proportion of TBT relative to the sum of BTs (a marker of recent pollution) in the most recent rock snail samples unexpectedly increased; this proportion therefore showed a generally decreasing but oscillatory trend over time. The results are consistent with the theoretical expectation of BT desorption from sediments; however, this natural phenomenon is now interpreted as a recurrent episode rather than a unique, transient event. Evidence of this subtle input improves our understanding of TBT persistence in the environment in Europe and worldwide.

  8. News on sputter theory: Molecular targets, nanoparticle desorption, rough surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Urbassek, Herbert M., E-mail: urbassek@rhrk.uni-kl.d [Fachbereich Physik und Forschungszentrum OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Anders, Christian [Fachbereich Physik und Forschungszentrum OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Rosandi, Yudi [Fachbereich Physik und Forschungszentrum OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Department of Physics, Universitas Padjadjaran, Jatinangor, Sumedang 45363 (Indonesia)

    2011-05-01

    Sputtering theory has existed as a mature and well-understood field of physics since the theory of collision-cascade sputtering has been developed in the late 1960s. In this presentation we outline several directions, in which the basic understanding of sputter phenomena has been challenged and new insight has been obtained recently. Sputtering of molecular solids: after ion impact on a molecular solid, not all of the impact energy is available for inducing sputtering. Part of the energy is converted into internal (rotational and vibrational) excitation of the target molecules, and part is used for molecule dissociation. Furthermore, exothermic or endothermic chemical reactions may further change the energy balance in the irradiated target. Nanoparticle desorption: usually, the flux of sputtered particles is dominated by monatomics; in the case of a pronounced spike contribution to sputtering, the contribution of clusters in the sputtered flux may become considerable. Here, we discuss the situation that nanoparticles were present on the surface, and outline mechanisms of how these may be desorbed (more or less intact) by ion or cluster impact. Rough surfaces: real surfaces are rough and contain surface defects (adatoms, surface steps, etc.). For grazing ion incidence, these influence the energy input into the surface dramatically. For such incidence angles sputtering vanishes for a flat terrace; however, ion impact close to a defect may lead to sputter yields comparable to those at normal incidence. In such cases sputtering also exhibits a pronounced azimuth and temperature dependence.

  9. Pesticide sorption and desorption from soils having different land use

    Directory of Open Access Journals (Sweden)

    Ismael Madrigal Monárrez

    2010-05-01

    Full Text Available This study was carried out within the framework of a multidisciplinary project for evaluating buffer zones for combating pesticide contamination of surface water. Such areas are effective in removing pesticides transported by run-off; however, little information is available about the fate of the pesticides so intercepted. Two herbicides having contrasting properties (isoproturon, moderately hydrophobic (log Kow = 2.5, diflufenican, strongly hydrophobic (log K ow = 4.9 and isopropylaniline (an isoproturon metabolite were used for characterising sorption and desorption from soil having three different land uses: grass buffer strip, woodland and cultivated plot. The experiments were carried out in controlled laboratory conditions using isoproturon labelled with 14C in the benzene ring. The results demonstrated that diflufenican and isopropilaniline retention was more significant than isoproturon in three soils. The three molecules’ Kd values revealed that isoproturon and diflufenicanil retention was more important in woodland soil where carbon content was more significant (ZB 0-2: Kd IPU = 15.1 Ls kg-1; Kd DFF = 169.2 Ls kg-1. Isopropilanilina Kd was higher in grass buffer strip soil (BE 0-2: Kd IPA = 53.1 L kg-1. These differences were related to different organic matter content and nature according to the type of land use.

  10. Adsorption and desorption characteristics of diphenylarsenicals in two contrasting soils

    Institute of Scientific and Technical Information of China (English)

    Anan Wang; Shixin Li; Ying Teng; Wuxin Liu; Longhua Wu; Haibo Zhang; Yujuan Huang

    2013-01-01

    Diphenylarsinic acid (DPAA) is formed during the leakage of aromatic arsenic chemical weapons in soils,is persistent in nature,and results in arsenic contamination in the field.The adsorption and desorption characteristics of DPAA were investigated in two typical Chinese soils,an Acrisol (a variable-charge soil) and a Phaeozem (a constant-charge soil).Their thermodynamics and some of the factors influencing them (i.e.,initial pH value,ionic strength and phosphate) were also evaluated using the batch method in order to understand the environmental fate of DPAA in soils.The results indicate that Acrisol had a stronger adsorption capacity for DPAA than Phaeozem.Soil DPAA adsorption was a spontaneous and endothermic process and the amount of DPAA adsorbed was affected significantly by variation in soil pH and phosphate.In contrast,soil organic matter and ionic strength had no significant effect on adsorption.This suggests that DPAA adsorption may be due to specific adsorption on soil mineral surfaces.Therefore,monitoring the fate of DPAA in soils is recommended in areas contaminated by leakage from chemical weapons.

  11. Electrical Characteristics and Desorption Kinetics of Soil Boron

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The status and activities of boron in soils were studied by the approach of electro-ultrafiltration (EUF). The samples of soils, including brown-red soil and calcareous alluvial soil, were collected from Hubei Province of China. The soil samples were incubated in saturated water and then their nutrients were ultrafiltrated with EUF equipment. Filtration and extraction were conducted in accordance with routine process, but fractions in anode and cathode were all collected. Analyses of B, K+, Mg2+, Ca2+, C1- and pH in fractions supposed that boron existed not only in a simple form of borate but also in ion-pair with cations partly in acidic soil,and borate was the primary form existing in the calcareous soil. In studying desorption kinetics with EUF,the boron content of Fractions 2~6 was accumulated, and the accumulative quantities were fit to time factors in three kinetic equations: the zero-order, first-order, and arabolic diffusion equations. Fit degree of the parabolic diffusion equation was the best, followed by the zero-order quation, and the first-order equation was the worst.

  12. Temperature dependence of CO desorption kinetics at a novel Pt-on-Au/C PEM fuel cell anode

    DEFF Research Database (Denmark)

    Pitois, A.; Pilenga, A.; Pfrang, A.;

    2010-01-01

    techniques. The temperature dependence of the CO desorption process on this system has been investigated using isotopic exchange experiments. The CO desorption kinetics have been studied as a function of temperature and flow rate. Desorption rate constants have been measured for a temperature range between...... 25 and 150 degrees C. These desorption rate constants have been compared with the benchmarking desorption rate data obtained for the commercial Pt/C catalyst under similar experimental conditions. A comparable desorption rate constant for the Pt-on-Au/C and Pt/C systems has been obtained at 25...... degrees C. The dependence in temperature of the desorption rate constants for the novel Pt-on-Au/C system is however much lower than that observed for the Pt/C system. This suggests that the nature of the substrate has a significant influence on the catalyst surface properties. It shows that, in surface...

  13. Proteomic Profiling of Plasma and Serum in Elderly Patients With Delirium

    NARCIS (Netherlands)

    B.C. van Munster; M.J. van Breemen; P.D. Moerland; D. Speijer; S.E. de Rooij; C.J. Pfrommer; M. Levi; M.W. Hollmann; J.M. Aerts; A.H. Zwinderman; J.C. Korevaar

    2009-01-01

    The aim of this study was to compare plasma and serum protein profiles in elderly acute hip fracture patients with and without delirium. The spectra from surface-enhanced laser desorption ionization (SELDI) using time-of-flight (TOF) mass spectrometry of 16 patients without and 16 patients with deli

  14. The adsorption-desorption cycle. Reversibility of the BSA-silica system

    NARCIS (Netherlands)

    Giacomelli, CE; Norde, W

    2001-01-01

    The reversibility of the adsorption-desorption cycle was established by comparing the thermostability (determined by differential scanning calorimetry) and secondary structure (obtained by circular dichroism spectroscopy) of BSA before adsorption, adsorbed on, and exchanged from silica particles. Ci

  15. The adsorption-desorption cycle. Reversibility of the BSA-silica system

    NARCIS (Netherlands)

    Giacomelli, C.E.; Norde, W.

    2001-01-01

    The reversibility of the adsorption–desorption cycle was established by comparing the thermostability (determined by differential scanning calorimetry) and secondary structure (obtained by circular dichroism spectroscopy) of BSA before adsorption, adsorbed on, and exchanged from silica particles. Ci

  16. Impact of activated carbon, biochar and compost on the desorption and mineralization of phenanthrene in soil.

    Science.gov (United States)

    Marchal, Geoffrey; Smith, Kilian E C; Rein, Arno; Winding, Anne; Wollensen de Jonge, Lis; Trapp, Stefan; Karlson, Ulrich G

    2013-10-01

    Sorption of PAHs to carbonaceous soil amendments reduces their dissolved concentrations, limiting toxicity but also potentially biodegradation. Therefore, the maximum abiotic desorption of freshly sorbed phenanthrene (≤5 mg kg(-1)) was measured in three soils amended with activated carbon (AC), biochar or compost. Total amounts of phenanthrene desorbed were similar between the different soils, but the amendment type had a large influence. Complete desorption was observed in the unamended and compost amended soils, but this reduced for biochar (41% desorbed) and AC (8% desorbed). Cumulative amounts mineralized were 28% for the unamended control, 19% for compost, 13% for biochar and 4% for AC. Therefore, the effects of the amendments in soil in reducing desorption were also reflected in the extents of mineralization. Modeling was used to analyze key processes, indicating that for the AC and charcoal treatments bacterial activity did not limit mineralization, but rather desorption into the dissolved phase. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n—HEXANE ON ACTIVATED CARBONS BY PTD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    LIZhong; WANGHongjuan; 等

    2001-01-01

    In this paper,six kinds of activated carbons such as Ag+-activated carbon,Cu2+activated carbon,Fe3+-activated carbon,activated carbon,Ba2+-activated carbon and Ca2+activated carbon were prepared.The model for estimating activated energy of desorption was established.Temperature-programmed desorption(TPD)experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons.Results showed that the activation energy for the desorption of n-hexanol on the Ag+-activated carbon,the Cu2+-activated carbon and the Fe3+-activated carbon were higher than those of n-hexanol on the activated carbon,the Ca2+-activated carbon and the Ba2+-activated carbon.

  18. ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, six kinds of activated carbons such as Ag+-activated carbon, Cu2+-activated carbon, Fe3+- activated carbon, activated carbon, Ba2+- activated carbon and Ca2+-activated carbon were prepared. The model for estimating activated energy of desorption was established. Temperature-programmed desorption (TPD) experiments were conducted to measure the TPD curves of n-hexanol and then estimate the activation energy for desorption of n-hexanol on the activated carbons. Results showed that the activation energy for the desorption of n-hexanol on the Ag+- activated carbon, the Cu2+- activated carbon and the Fe3+- activated carbon were higher than those of n-hexanol on the activated carbon, the Ca2+- activated carbon and the Ba2+- activated carbon.

  19. Study on impurity desorption induced by femtosecond pulse laser based on a stochastic process model

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    With the advantages on non-equilibrium heating and desorption induced by electronic transition, the femtosecond pulse laser introduces a new way for solving the problem of impurity pollution adsorbed on a solid thin film in micro-electro-mechanical systems (MEMS). A model based on stochastic processes was established for stimulated desorption induced by the femtosecond pulse laser to interpret the interaction of the optically excited hot electrons with the adsorbed molecules in a metal substrate. Numerical simulation results reveal a time-dependent desorption probability of adsorbed molecules and indicate that how key parameters of femtosecond pulse laser, such as incident laser energy flux, pulse duration, and wavelength of pulse, have a great effect on the desorption probability.

  20. Low energy electron stimulated desorption from DNA films dosed with oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Mirsaleh-Kohan, Nasrin; Bass, Andrew D.; Cloutier, Pierre; Massey, Sylvain; Sanche, Leon [Groupe en sciences des radiations, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke, Quebec J1H 5N4 (Canada)

    2012-06-21

    Desorption of anions stimulated by 1-18 eV electron impact on self-assembled monolayer (SAM) films of single DNA strands is measured as a function of film temperature (50-250 K). The SAMs, composed of 10 nucleotides, are dosed with O{sub 2}. The OH{sup -} desorption yields increase markedly with exposure to O{sub 2} at 50 K and are further enhanced upon heating. In contrast, the desorption yields of O{sup -}, attributable to dissociative electron attachment to trapped O{sub 2} molecules decrease with heating. Irradiation of the DNA films prior to the deposition of O{sub 2} shows that this surprising increase in OH{sup -} desorption, at elevated temperatures, arises from the reaction of O{sub 2} with damaged DNA sites. These results thus appear to be a manifestation of the so-called 'oxygen fixation' effect, well known in radiobiology.

  1. Research on the gas desorption law of the consumingly destruct coal

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiang-jun; WANG Zhao-feng; YANG Hong-min; XIAO Dong-hui

    2008-01-01

    To solve the issues of calculating gas loss quantity during sampling, simulated gas desorption process of the consumingly destruct coal with the assembly simulation testing device. Through an analysis of the simulation test datum using SPSS software,established a new formula that can be better description on gas desorption process, more accurate calculation of the gas loss quantity during sampling process, and calculating releasable gas quantity during a certain period. Aimed at the new formula, the best time of taking sample is confirmed 3 minutes for consumingly destruct coal, the computative error is less than 10%. Through experiment at laboratory and locale, the new formula could well describe consumingly destruct coal gas desorption law, and it has high calculation precision of gas loss quantity in sampling and desorption quanlity.

  2. EFFECTS OF BIOSOLIDS ON SORPTION AND DESORPTION BEHAVIOR OF CADMIUM IN BIOSOLIDS-AMENDED SOILS

    Science.gov (United States)

    Cadmium sorption and desorption experiments were conducted on different fractions of soils amended with different biosolids with varying chemical properties and unamended soil (control). Biosolids addition increased the slope of the Cd sorption isotherms compared to the control s...

  3. Catalitic effect of Co on hydrogen desorption form nanostucturated magnesium hydride

    Directory of Open Access Journals (Sweden)

    Matović Ljiljana Lj.

    2008-01-01

    Full Text Available To study the influence of 3d transition metal addition on desorption kinetics of MgH2 ball milling of MgH2-Co blends was performed under Ar. Microstructural and morphological characterization, performed by XRD and SEM, show a huge correlation with thermal stability and hydrogen desorption properties investigated by DSC. A complex desorption behavior is correlated with the dispersion of the metal additive particles on hydride matrix. The activation energy for H2 desorption from MgH2-Co composite was calculated from both non-isothermal and isothermal methods to be 130 kJ/mol which means that mutually diffusion and nucleation and growth of new phase control the dehydration process.

  4. Modelling of hydrogen thermal desorption spectrum in nonlinear dynamical boundary-value problem

    Science.gov (United States)

    Kostikova, E. K.; Zaika, Yu V.

    2016-11-01

    One of the technological challenges for hydrogen materials science (including the ITER project) is the currently active search for structural materials with various potential applications that will have predetermined limits of hydrogen permeability. One of the experimental methods is thermal desorption spectrometry (TDS). A hydrogen-saturated sample is degassed under vacuum and monotone heating. The desorption flux is measured by mass spectrometer to determine the character of interactions of hydrogen isotopes with the solid. We are interested in such transfer parameters as the coefficients of diffusion, dissolution, desorption. The paper presents a distributed boundary-value problem of thermal desorption and a numerical method for TDS spectrum simulation, where only integration of a nonlinear system of low order (compared with, e.g., the method of lines) ordinary differential equations (ODE) is required. This work is supported by the Russian Foundation for Basic Research (project 15-01-00744).

  5. Hydrogen absorption and desorption in nanocrystalline LaMg{sub 2}Ni

    Energy Technology Data Exchange (ETDEWEB)

    Di Chio, M. [Dipartimento di Chimica IFM and NIS-Centre of Excellence, Universita di Torino, Via P. Giuria, 9-10125 Torino (Italy); Schiffini, L. [Dipartimento di Chimica, Universita di Sassari, Via Vienna, 2-07100 Sassari (Italy); Enzo, S. [Dipartimento di Chimica, Universita di Sassari, Via Vienna, 2-07100 Sassari (Italy); Cocco, G. [Dipartimento di Chimica, Universita di Sassari, Via Vienna, 2-07100 Sassari (Italy); Baricco, M. [Dipartimento di Chimica IFM and NIS-Centre of Excellence, Universita di Torino, Via P. Giuria, 9-10125 Torino (Italy)]. E-mail: marcello.baricco@unito.it

    2007-05-31

    Hydrogen absorption and desorption properties in LaMg{sub 2}Ni compound are presented. Nanostructured phases have been obtained by means of ball milling in order to study the influence of the microstructure on the absorption/desorption properties. The structural and hydriding properties were examined by X-ray diffraction, thermal analysis, hydrogen pressure-composition and thermal desorption measurements. Ball milling of as-cast compound gives a significant refinement of the microstructure. Hydrogenation at 443 K leads to the formation of LaMg{sub 2}NiH{sub 7}, but at higher temperatures (523 K) LaH{sub 2} is produced. Two hours of ball milling promote the formation of LaH{sub 2} under hydrogenation at 443 K. Thermal desorption up to 983 K of hydrogenated samples leads again to parent LaMg{sub 2}Ni phase.

  6. omniSpect: an open MATLAB-based tool for visualization and analysis of matrix-assisted laser desorption/ionization and desorption electrospray ionization mass spectrometry images.

    Science.gov (United States)

    Parry, R Mitchell; Galhena, Asiri S; Gamage, Chaminda M; Bennett, Rachel V; Wang, May D; Fernández, Facundo M

    2013-04-01

    We present omniSpect, an open source web- and MATLAB-based software tool for both desorption electrospray ionization (DESI) and matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI) that performs computationally intensive functions on a remote server. These functions include converting data from a variety of file formats into a common format easily manipulated in MATLAB, transforming time-series mass spectra into mass spectrometry images based on a probe spatial raster path, and multivariate analysis. OmniSpect provides an extensible suite of tools to meet the computational requirements needed for visualizing open and proprietary format MSI data.

  7. Heavy-ion-induced desorption of organic molecules studied with Langmuir-Blodgett multilayer systems (DE)

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, R.; Schoppmann, C.; Brandl, D.; Ostrowski, A.; Voit, H. (Physikalisches Institut der Universitaet Erlangen-Nuernberg D-8520 Erlangen, (Germany)); Johannsmann, D.; Knoll, W. (Max-Planck-Institut fuer Polymerforschung Mainz D-6500 Mainz, (Germany))

    1991-07-01

    Heavy-ion-induced desorption has been studied with samples consisting of Langmuir-Blodgett films made from Cd salts of fatty acids. The experiments confirm the result of previous works that heavy ions drill a crater into the sample surface. The explicit dependence of the crater depth on the electronic energy loss could be determined from the experiments. The craters exhibit the shape of a symmetric cone as obtained from a desorption model applied to the experimental data.

  8. Oxygen Sorption and Desorption Properties of Selected Lanthanum Manganites and Lanthanum Ferrite Manganites

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Skou, Eivind M.; Jacobsen, Torben

    2015-01-01

    Temperature‐programmed desorption (TPD) with a carrier gas was used to study the oxygen sorption and desorption properties of oxidation catalysts and solid‐oxide fuel cell (SOFC) cathode materials (La0.85Sr0.15)0.95MnO3+δ (LSM) and La0.60Sr0.40Fe0.80Mn0.20O3‐δ (LSFM). The powders were characteriz...

  9. Desorption of organo phosphorous pesticides from soil with wastewater and surfactant solution

    OpenAIRE

    Hernandez-Soriano, Maria del Carmen; Mingorance, Maria Dolores; Peña, Aranzazu

    2008-01-01

    Surfactants can be introduced in the environment by wastewater discharge, point-charge pollution or deliberate action, e.g. to remediate contaminated soil or groundwater. The irrigation of soil with wastewater containing surfactants may modify pesticide desorption from soil, thus affecting their environmental fate. Desorption from soil of the plain of Granada (South-eastern Spain) of two organophosphorous pesticides, diazinon and dimethoate, differing in solubility and hydrophobicity...

  10. Various causes behind the desorption hysteresis of carboxylic acids on mudstones.

    Science.gov (United States)

    Rasamimanana, S; Lefèvre, G; Dagnelie, R V H

    2017-02-01

    Adsorption desorption is a key factor for leaching, migration and (bio)degradation of organic pollutants in soils and sediments. Desorption hysteresis of apolar organic compounds is known to be correlated with adsorption/diffusion into soil organic matter. This work focuses on the desorption hysteresis of polar organic compounds on a natural mudstone sample. Acetic, citric and ortho-phthalic acids displayed adsorption-desorption hysteresis on Callovo-Oxfordian mudstone. The non-reversible behaviours resulted from three different mechanisms. Adsorption and desorption kinetics were evaluated using 14C- and 3H-labelled tracers and an isotopic exchange method. The solid-liquid distribution ratio of acetate decreased using a NaN3 bactericide, indicating a rapid bacterial consumption compared with negligible adsorption. The desorption hysteresis of phthalate was apparent and suppressed by the equilibration of renewal pore water with mudstone. This confirms the significant and reversible adsorption of phthalate. Finally, persistent desorption hysteresis was evidenced for citrate. In this case, a third mechanism should be considered, such as the incorporation of citrate in the solid or a chemical perturbation, leading to strong desorption resilience. The results highlighted the different pathways that polar organic pollutants might encounter in a similar environment. Data on phthalic acid is useful to predict the retarded transport of phthalate esters and amines degradation products in sediments. The behaviour of citric acid is representative of polydentate chelating agents used in ore and remediation industries. The impact of irreversible adsorption on solid/solution partitioning and transport deserves further investigation.

  11. A Monte Carlo study of temperature-programmed desorption spectra with attractive lateral interactions

    CERN Document Server

    Jansen, A P J

    1995-01-01

    We present results of a Monte Carlo study of temperature-programmed desorption in a model system with attractive lateral interactions. It is shown that even for weak interactions there are large shifts of the peak maximum temperatures with initial coverage. The system has a transition temperature below which the desorption has a negative order. An analytical expression for this temperature is derived. The relation between the model and real systems is discussed.

  12. Effect of pH on desorption of CO2 from alkanolamine - rich solvents

    Science.gov (United States)

    Du, Min

    2017-08-01

    Adipic acid was used as a pH regulator, which was added to 0.4 mol/L MEA, DEA and MDEA solvents during CO2 desorption process. It is found that when pH value of the solvents swing between 8-10, CO2 desorption rate enhanced, and energy consumption has declined obviously. This research may have reference significance on optimization of alkanolamine CO2 capture process.

  13. Treating high-mercury-containing lamps using full-scale thermal desorption technology.

    Science.gov (United States)

    Chang, T C; You, S J; Yu, B S; Chen, C M; Chiu, Y C

    2009-03-15

    The mercury content in high-mercury-containing lamps are always between 400 mg/kg and 200,000 mg/kg. This concentration is much higher than the 260 mg/kg lower boundary recommended for the thermal desorption process suggested by the US Resource Conservation and Recovery Act. According to a Taiwan EPA survey, about 4,833,000 cold cathode fluorescent lamps (CCFLs), 486,000 ultraviolet lamps and 25,000 super high pressure mercury lamps (SHPs) have been disposed of in the industrial waste treatment system, producing 80, 92 and 9 kg-mercury/year through domestic treatment, offshore treatment and air emissions, respectively. To deal with this problem we set up a full-scale thermal desorption process to treat and recover the mercury from SHPs, fluorescent tube tailpipes, fluorescent tubes containing mercury-fluorescent powder, and CCFLs containing mercury-fluorescent powder and monitor the use of different pre-heating temperatures and desorption times. The experimental results reveal that the average thermal desorption efficiency of SHPs and fluorescent tube tailpipe were both 99.95%, while the average thermal desorption efficiencies of fluorescent tubes containing mercury-fluorescent powder were between 97% and 99%. In addition, a thermal desorption efficiency of only 69.37-93.39% was obtained after treating the CCFLs containing mercury-fluorescent powder. These differences in thermal desorption efficiency might be due to the complexity of the mercury compounds contained in the lamps. In general, the thermal desorption efficiency of lamps containing mercury-complex compounds increased with higher temperatures.

  14. Desorption of Furfural from Bimetallic Pt-Fe Oxides/Alumina Catalysts

    OpenAIRE

    Gloria Lourdes Dimas-Rivera; Javier Rivera de la Rosa; Carlos J. Lucio-Ortiz; José Antonio De los Reyes Heredia; Virgilio González González; Tomás Hernández

    2014-01-01

    In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA). The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM) imaging revealed the intimate connection betwe...

  15. Carbon Dioxide reduction by non-equilibrium electrocatalysis plasma reactor

    Energy Technology Data Exchange (ETDEWEB)

    Amouroux, J; Cavadias, S [LGPPTS- ENSCP/UPMC 11 rue P. t M. Curie 75231 Paris cedex 05 (France); Doubla, A, E-mail: simeon-cavadias@chimie-paristech.fr [Laboratoire de Chimie Minerale, Universite de Yaounde I, BP 812 (Cameroon)

    2011-03-15

    A possible strategy to increase the added value from CCS, is to consider it as a raw material for the production of liquid fuels, or chemical products. The most studied ways related to CO{sub 2} reduction, with formation of molecules such as CH{sub 3}OH or syngas, is the reaction with H{sub 2} (exothermic reaction needing catalytic activation), or CH{sub 4} (endothermic reaction taking place at high temperature) with the use of a catalyst. The synthesis of CH{sub 3}OH is performed on Lewis acid type sites (default of electrons) Cu/Zn/Al{sub 2}O{sub 3}. However the products of the reaction i.e. the water and methanol molecules, are very polar, resulting in a very low desorption rate. So in this reaction the key step is water desorption (Lewis basis). The increase of temperature in order to increase this desorption rate, leads to a cracking and the deposition of carbon in the catalyst, limiting its lifetime. Plasma driven catalysis allows firstly, a vibrational activation of CO{sub 2}, H{sub 2} or CH{sub 4} through electron-molecule collisions, making easier their dissociation at low temperature and secondly expels water from the catalyst sites by supplying electrons (electropolarisation). The results show an increase of the yield in CH{sub 3}OH with plasma and catalyst, confirming the action of the plasma. However energy consumption remains relatively high.

  16. Plasma Antenna

    OpenAIRE

    N M Vijay

    2014-01-01

    The fundamental base of plasma antenna is the use of an ionized medium as a conductor. The plasma antenna is a radiofrequency antenna formed by a plasma columns, Filaments or sheets, which are excited by a surface wave. The relevance of this device is how rapidly it can be turned on and off, only applying an electrical pulse. Besides its wide carrier frequency, the great directivity and controllable antenna shape. Otherwise a disadvantage is that it needs energy to be ionized....

  17. Electrothermal adsorption and desorption of volatile organic compounds on activated carbon fiber cloth.

    Science.gov (United States)

    Son, H K; Sivakumar, S; Rood, M J; Kim, B J

    2016-01-15

    Adsorption is an effective means to selectively remove volatile organic compounds (VOCs) from industrial gas streams and is particularly of use for gas streams that exhibit highly variable daily concentrations of VOCs. Adsorption of such gas streams by activated carbon fiber cloths (ACFCs) and subsequent controlled desorption can provide gas streams of well-defined concentration that can then be more efficiently treated by biofiltration than streams exhibiting large variability in concentration. In this study, we passed VOC-containing gas through an ACFC vessel for adsorption and then desorption in a concentration-controlled manner via electrothermal heating. Set-point concentrations (40-900 ppm(v)) and superficial gas velocity (6.3-9.9 m/s) were controlled by a data acquisition and control system. The results of the average VOC desorption, desorption factor and VOC in-and-out ratio were calculated and compared for various gas set-point concentrations and superficial gas velocities. Our results reveal that desorption is strongly dependent on the set-point concentration and that the VOC desorption rate can be successfully equalized and controlled via an electrothermal adsorption system.

  18. Photoinduced Br Desorption from CsBr Thin Films Grown on Cu(100)

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, Matthew T.; Joly, Alan G.; Hess, Wayne P.; Shluger, AL

    2015-10-22

    Thin films of CsBr deposited onto metals such as copper are potential photocathode materials for light sources and other applications. We investigate desorption dynamics of Br atoms from CsBr films grown on insulator (KBr, LiF) and metal (Cu) substrates induced by sub-bandgap 6.4 eV laser pulses. The experimental results demonstrate that the peak kinetic energy of Br atoms desorbed from CsBr/Cu films is much lower than that for the hyperthermal desorption from CsBr/LiF films. Kelvin probe measurements indicate negative charge at the surface following Br desorption from CsBr/Cu films. Our ab initio calculations of excitons at CsBr surfaces demonstrate that this behavior can be explained by an exciton model of desorption including electron trapping at the CsBr surface. Trapped negative charges reduce the energy of surface excitons available for Br desorption. We examine the electron-trapping characteristics of low-coordinated sites at the surface, in particular, divacancies and kink sites. We also provide a model of cation desorption caused by Franck-Hertz excitation of F centers at the surface in the course of irradiation of CsBr/Cu films. These results provide new insights into the mechanisms of photoinduced structural evolution of alkali halide films on metal substrates and activation of metal photocathodes coated with CsBr.

  19. Characteristics and applications of gas desorption with excavation disturbances in coal mining

    Institute of Scientific and Technical Information of China (English)

    Jiachen Wang; Renlun Wu; Peng Zhang

    2015-01-01

    According to the deficiency of experiment system for gas adsorption and desorption in coal mass, a large scale experiment system is developed independently by researchers. This experiment system is composed of primary and auxiliary boxes, power transmission system, mining system, loading system, gas charging system, data monitoring and intelligent acquisition system. The maximum experiment coal consumption is 1200 kg, the mining system is developed to conduct experiment for gas desorption under excavating disturbance, and the plane-charging cribriform ventilation device is developed to realize uniform ventilation for experiment coal sample, which is accord with the actual gas source situation of coal bed. The desorption characteristics of gas in coal are experimentally studied under the conditions of nature and mining using the experiment system. The results show that, compare with nature condition, the permeability of coal and the velocity of gas desorption could significantly increase under the influence of coal pressure relief and destruction caused by mining, and the degree of gas desorption could somewhat increase too. Finally, pressure relief gas extraction of current seam and adjacent seams after mining in a certain coal mine of Yangquan mining area are introduced, and the gas desorption experiment results is verified by analyzing the effect of gas extraction.

  20. Enhanced hydrogen desorption property of MgH{sub 2} with the addition of cerium fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Huai-Jun, E-mail: huaijun.lin.489@s.kyushu-u.ac.jp [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Matsuda, Junko [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Li, Hai-Wen [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan); Zhu, Min [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); China–Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510640 (China); Akiba, Etsuo [Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan)

    2015-10-05

    Highlights: • Activation energy of MgH{sub 2} desorption is remarkably reduced with the dopant of CeF{sub 4}. • The improvement might be attributed to new Ce–F–Mg species at the CeF{sub 4}/MgH{sub 2} interface. • Easy electron transfer induced from the high valence Ce-cation benefits MgH{sub 2} desorption. - Abstract: Hydrogen desorption property of MgH{sub 2} doped with cerium fluorides with different valences prepared using ball milling has been studied. CeF{sub 4} is catalytically active for hydrogen desorption of MgH{sub 2}. Hydrogen desorption temperature and apparent activation energy of MgH{sub 2} are significantly reduced with dopant of 2 mol% of CeF{sub 4}, which might be attributed to the formation of a new Ce–F–Mg specie at the CeF{sub 4}/MgH{sub 2} interface and the easy electron transfer induced from the high valence Ce-cation. The apparent activation energy of hydrogen desorption of MgH{sub 2} is reduced from ∼160 kJ/mol to ∼110 kJ/mol with the dopant of CeF{sub 4}.

  1. Effects of organic acids on cadmium and copper sorption and desorption by two calcareous soils.

    Science.gov (United States)

    Najafi, Sarvenaz; Jalali, Mohsen

    2015-09-01

    Low molecular weight organic acids (LMWOAs) present in soil alter equilibrium pH of soil, and consequently, affect heavy metal sorption and desorption on soil constitutes. This study was conducted to investigate the effects of different concentrations (0.1, 1, 2.5, 5, 10, 30, 40, 50, 70, and 100 mM) of citric, malic, and oxalic acids on sorption and desorption of cadmium (Cd) and copper (Cu) in two calcareous soils. Increasing the concentrations of three LMWOAs decreased the equilibrium pH of soil solutions. The results indicated that increase in organic acids concentrations generally reduced Cd and Cu sorption in soils. Increase concentrations of LMWOAs generally promoted Cd and Cu desorption from soils. A valley-like curve was observed for desorption of Cu after the citric acid concentration increment in soil 2. Increasing the concentrations of three LMWOAs caused a marked decrease in Kd(sorp) values of Cd and Cu in soils. In general, citric acid was the most effective organic acid in reducing sorption and increasing desorption of both metals, and oxalic acid had the minimal impact. The results indicated that LMWOAs had a greater impact on Cu sorption and desorption than Cd, which can be attributed to higher stability constants of organic acids complexes with Cu compared to Cd. It can be concluded that by selecting suitable type and concentration of LMWOAs, mobility, and hence, bioavailability of heavy metals can be changed. So, environmental implications concerning heavy metals mobility might be derived from these findings.

  2. ATRAZINE ADSORPTION-DESORPTION BEHAVIOR IN DAREHASALUIE KAVAR CORN FIELD SOIL

    Directory of Open Access Journals (Sweden)

    M. Dehghani, S. Nasseri, S. Amin, K. Naddafi, M. Yunesian, M. Taghavi and N. Maleki

    2005-10-01

    Full Text Available Adsorption desorption behaviors of widely applied atrazine soil were studied, employing a batch technique as a case study in Darehasaluie Kavar corn field in Fars Province in 2005. Samples were collected into 0 to 20 cm soil depth, where was cultivated under a crop rotation (corn-wheat during the past 10 years. Sorption kinetics exhibited two phenomena: an immediate rapid sorption (1.31 µg/g soil after 12 hours followed by a slow sorption process (1.37 µg/g soil after 24 hours. Desorption behavior of atrazine was similar to its adsorption, but at a very slower rate. Atrazine desorption efficiencies were much less effective and incomplete even after a long equilibration time (only 9.16% after 96 hours. The adsorption-desorption rate for most of the time was positively related to the amount of applied atrazine and the time required for equilibration (P<0.01. Desorption data exhibited hysteresis phenomena. Atrazine adsorption data described well according to Freundlich (r2=0.95, Langmuir (r2=0.82 and Temkin (r2=0.84 isotherms. However, the fit to Freundlich adsorption model in a non linear form (1/n <1 was closer than the others. Desorption isotherm could be well described by the Temkin (r2=0.96 and Freundlich (r2=0.92 isotherms, but the fit to Temkin model was closer than that of Freundlich.

  3. Plasma physics

    CERN Document Server

    Drummond, James E

    2013-01-01

    A historic snapshot of the field of plasma physics, this fifty-year-old volume offers an edited collection of papers by pioneering experts in the field. In addition to assisting students in their understanding of the foundations of classical plasma physics, it provides a source of historic context for modern physicists. Highly successful upon its initial publication, this book was the standard text on plasma physics throughout the 1960s and 70s.Hailed by Science magazine as a ""well executed venture,"" the three-part treatment ranges from basic plasma theory to magnetohydrodynamics and microwa

  4. Desorption of a methamphetamine surrogate from wallboard under remediation conditions

    Science.gov (United States)

    Poppendieck, Dustin; Morrison, Glenn; Corsi, Richard

    2015-04-01

    Thousands of homes in the United States are found to be contaminated with methamphetamine each year. Buildings used to produce illicit methamphetamine are typically remediated by removing soft furnishings and stained materials, cleaning and sometimes encapsulating surfaces using paint. Methamphetamine that has penetrated into paint films, wood and other permanent materials can be slowly released back into the building air over time, exposing future occupants and re-contaminating furnishings. The objective of this study was to determine the efficacy of two wallboard remediation techniques for homes contaminated with methamphetamine: 1) enhancing desorption by elevating temperature and relative humidity while ventilating the interior space, and 2) painting over affected wallboard to seal the methamphetamine in place. The emission of a methamphetamine surrogate, N-isopropylbenzylamine (NIBA), from pre-dosed wallboard chambers over 20 days at 32 °C and two values of relative humidity were studied. Emission rates from wallboard after 15 days at 32 °C ranged from 35 to 1400 μg h-1 m-2. Less than 22% of the NIBA was removed from the chambers over three weeks. Results indicate that elevating temperatures during remediation and latex painting of impacted wallboard will not significantly reduce freebase methamphetamine emissions from wallboard. Raising the relative humidity from 27% to 49% increased the emission rates by a factor of 1.4. A steady-state model of a typical home using the emission rates from this study and typical residential building parameters and conditions shows that adult inhalation reference doses for methamphetamine will be reached when approximately 1 g of methamphetamine is present in the wallboard of a house.

  5. Mercury speciation during in situ thermal desorption in soil

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Min, E-mail: cmpark80@gmail.com; Katz, Lynn E.; Liljestrand, Howard M.

    2015-12-30

    Highlights: • Impact of soil conditions on distribution and phase transitions of Hg was identified. • Metallic Hg was slowly transformed to Hg{sup 0} gas until the temperature reached 358.15 K. • Phase change of HgCl{sub 2(s)} completely occurred without decomposition at 335.15 K. • HgS remained solid in dry soil sharply decreased in the narrow temperature range. • Hg gas can be easily captured with higher vapor pressures of soil compositions. - Abstract: Metallic mercury (Hg{sup 0}) and its compounds are highly mobile and toxic environmental pollutants at trace level. In situ thermal desorption (ISTD) is one of the soil remediation processes applying heat and vacuum simultaneously. Knowledge of thermodynamic mercury speciation is imperative to understand the fate and transport of mercury during thermal remediation and operate the treatment processes in a cost-effective manner. Hence, speciation model for inorganic mercury was developed over a range of environmental conditions to identify distribution of dissolved mercury species and potential transformations of mercury at near source environment. Simulation of phase transitions for metallic mercury, mercury(II) chloride and mercury sulfide with temperature increase showed that complete vaporization of metallic mercury and mercury(II) chloride were achieved below the boiling point of water. The effect of soil compositions on mercury removal was also evaluated to better understand thermal remediation process. Higher vapor pressures expected both from soil pore water and inorganic carbonate minerals in soil as well as creation of permeability were significant for complete vaporization and removal of mercury.

  6. Carbon dioxide sorption/ desorption characteristics of coals in Taiwan

    Science.gov (United States)

    Chien-Hung, Hsiao; Loung-Yie, Tsai

    2013-04-01

    Geological sequestration of CO2 into depleted oil reservoir, saline aquifer or unmineable coal seam is now being actively investigated for the purpose of reducing greenhouse gas in the atmosphere. Understanding the physical, chemical, and thermodynamic phenomena occurred with CO2 injection is very important in marking a reliable prediction of sequestration. This study examined the feasibility of carbon dioxide sequestration into unmineable coal seams in Taiwan. A total of 20 Miocene-aged coal samples from Western Foothill Belt, NW Taiwan, were collected. The stratigraphy include Mushan, Shihti, and Nanchuang Formation from bottom up. Proximate and petrographic analyses include maceral composition, Vitrinite reflectance were also measured. Carbon dioxide adsorption isotherms were analyzed at 35 degrees Celsius and up to 800 psi, by using a gravimetric ad/desorption apparatus. Isotherms were then fitted with a modified Langmuir Isotherm model by using Langmuir Pressure and Langmuir Volume so the model can be applied to supercritical conditions. According to the result of adsorption experiment, the pressure and temperature were quite significant. The gas storage capacity of CO2 was about 400 600 scf/ton at pressure up to 800 psi. Comparing the results of adsorption capacity with Proximate analysis and vitrinite reflectance, the Langmuir Volume shows a strong positive correlation with fixed carbon and vitrinite content. Furthermore, Adsorption capacity is closely related to micropores which were also rank and maceral dependent. It is noticed that the observed coal pore structures were affected by rank, and then exhibit have different diffusion rate of CO2.Finally, images under SEM were evaluated to understand the pathways of gas sorption.

  7. Single Component Sorption-Desorption Test Experimental Design Approach Discussions

    Energy Technology Data Exchange (ETDEWEB)

    Phil WInston

    2011-09-01

    A task was identified within the fission-product-transport work package to develop a path forward for doing testing to determine behavior of volatile fission products behavior and to engage members of the NGNP community to advise and dissent on the approach. The following document is a summary of the discussions and the specific approaches suggested for components of the testing. Included in the summary isare the minutes of the conference call that was held with INL and external interested parties to elicit comments on the approaches brought forward by the INL participants. The conclusion was that an initial non-radioactive, single component test will be useful to establish the limits of currently available chemical detection methods, and to evaluated source-dispersion uniformity. In parallel, development of a real-time low-concentration monitoring method is believed to be useful in detecting rapid dispersion as well as desorption phenomena. Ultimately, the test cycle is expected to progress to the use of radio-traced species, simply because this method will allow the lowest possible detection limits. The consensus of the conference call was that there is no need for an in-core test because the duct and heat exchanger surfaces that will be the sorption target will be outside the main neutron flux and will not be affected by irradiation. Participants in the discussion and contributors to the INL approach were Jeffrey Berg, Pattrick Calderoni, Gary Groenewold, Paul Humrickhouse, Brad Merrill, and Phil Winston. Participants from outside the INL included David Hanson of General Atomics, Todd Allen, Tyler Gerczak, and Izabela Szlufarska of the University of Wisconsin, Gary Was, of the University of Michigan, Sudarshan Loyalka and Tushar Ghosh of the University of Missouri, and Robert Morris of Oak Ridge National Laboratory.

  8. Laser Desorption Supersonic Jet Spectroscopy of Hydrated Tyrosine

    Science.gov (United States)

    Oba, Hikari; Shimozono, Yoko; Ishiuchi, Shun-Ichi; Fujii, Masaaki; Carcabal, Pierre

    2013-06-01

    The structure of tyrosine (tyr) consists of amino-acid chain and phenol, and it has roughly two possible binding sites for water, amino-acid site and phenolic OH site. Investigating how water molecule binds to tyr will give fundamental information for hydrations of peptide and protein. Resonance enhanced multi photon ionization (REMPI) spectrum of tyr-water 1:1 cluster has already been reported by de Vries and co-workers, however, no analysis on the hydrated structures has been reported. In the REMPI spectrum, two clusters of bands are observed; one appears at ˜35600 cm^{-1} energy region which is the almost same with 0-0 transitions of tyr monomer, and another is observed at ˜300 cm^{-1} lower than the former. Based on the electronic transition energy of phenylalanine and the hydrated clusters, the former is expected to be derived from a structure that water binds to amino acid site. On the other hand, it is plausibly predicted that the latter originates from a structure that water binds to phenolic OH group, because the electronic transition of mono hydrated phenol is ˜300 cm^{-1} red-shifted from the monomer. We applied IR dip spectroscopy which can measure conformer selective IR spectra to the tyr-(H_{2}O)_{1} clusters by using laser desorption supersonic jet technique to confirm the assignments. Especially in the phenolic OH bound isomer, it was found that the intra molecular hydrogen bond within amino-acid chain, which is far from the water molecule and cannot interact directly with each other, is strengthened by the hydration. A. Abio-Riziq et al., J. Phys. Chem. A, 115, 6077 (2011). Y. Shimozono, et al., Phys. Chem. Chem. Phys., (2013) DOI: 10.1039/c3cp43573c. T. Ebata et al., Phys. Chem. Chem. Phys., 8, 4783 (2006). T. Watanabe et al., J. Chem. Phys., 105, 408 (1996).

  9. Desorption Kinetics of Ar, Kr, Xe, N2, O2, CO, Methane, Ethane, and Propane from Graphene and Amorphous Solid Water Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. Scott; May, Robert A.; Kay, Bruce D.

    2016-03-03

    The desorption kinetics for Ar, Kr, Xe, N2, O2, CO, methane, ethane, and propane from grapheme covered Pt(111) and amorphous solid water (ASW) surfaces are investigated using temperature programmed desorption (TPD). The TPD spectra for all of the adsorbates from graphene have well-resolved first, second, third, and multi- layer desorption peaks. The alignment of the leading edges is consistent the zero-order desorption for all of the adsorbates. An Arrhenius analysis is used to obtain desorption energies and prefactors for desorption from graphene for all of the adsorbates. In contrast, the leading desorption edges for the adsorbates from ASW do not align (for coverages < 2 ML). The non-alignment of TPD leading edges suggests that there are multiple desorption binding sites on the ASW surface. Inversion analysis is used to obtain the coverage dependent desorption energies and prefactors for desorption from ASW for all of the adsorbates.

  10. Fate and transport with material response characterization of green sorption media for copper removal via desorption process.

    Science.gov (United States)

    Chang, Ni-Bin; Houmann, Cameron; Lin, Kuen-Song; Wanielista, Martin

    2016-07-01

    Multiple adsorption and desorption cycles are required to achieve the reliable operation of copper removal and recovery. A green sorption media mixture composed of recycled tire chunk, expanded clay aggregate, and coconut coir was evaluated in this study for its desorptive characteristics as a companion study of the corresponding adsorption process in an earlier publication. We conducted a screening of potential desorbing agents, batch desorption equilibrium and kinetic studies, and batch tests through 3 adsorption/desorption cycles. The desorbing agent screening revealed that hydrochloric acid has good potential for copper desorption. Equilibrium data fit the Freundlich isotherm, whereas kinetic data had high correlation with the Lagergren pseudo second-order model and revealed a rapid desorption reaction. Batch equilibrium data over 3 adsorption/desorption cycles showed that the coconut coir and media mixture were the most resilient, demonstrating they could be used through 3 or more adsorption/desorption cycles. FE-SEM imaging, XRD, and EDS analyses supported the batch adsorption and desorption results showing significant surface sorption of CuO species in the media mixture and coconut coir, followed by partial desorption using 0.1 M HCl as a desorbing agent. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Optimization and kinetic modeling of cadmium desorption from citrus peels: A process for biosorbent regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Njikam, Eloh, E-mail: ennjikam@alaska.edu [Department of Civil and Environmental Engineering, University of Alaska Fairbanks, P.O. Box 755900, Fairbanks, AK 99775 (United States); Schiewer, Silke, E-mail: sschiewer@alaska.edu [Department of Civil and Environmental Engineering, University of Alaska Fairbanks, P.O. Box 755900, Fairbanks, AK 99775 (United States)

    2012-04-30

    Graphical abstract: Cadmium was completely and quickly desorbed from grapefruit peels using 0.01 M HNO{sub 3}. The kinetics followed a novel 1st or 2nd order kinetic model, related to the remaining metal bound as the rate-determining reactant concentration. For 0.001 M HNO{sub 3}, desorption was incomplete and the model fit less perfect. Highlights: Black-Right-Pointing-Pointer Metal desorption was over 90% complete within 50 min for most desorbents. Black-Right-Pointing-Pointer Models for biosorbent desorption kinetics were developed. Black-Right-Pointing-Pointer Desorption kinetics best fit a novel first-order model related to remaining metal bound. Black-Right-Pointing-Pointer Cd uptake after desorption by HNO{sub 3} was similar to the original uptake. Black-Right-Pointing-Pointer The optimal desorbent was 0.1 or 0.01 M acid, being fast, efficient and cheap. - Abstract: Citrus peel biosorbents are efficient in removing heavy metals from wastewater. Heavy metal recovery and sorbent regeneration are important for the financial competitiveness of biosorption with other processes. The desorbing agents HNO{sub 3}, NaNO{sub 3}, Ca(NO{sub 3}){sub 2}, EDTA, S, S-EDDS, and Na-Citrate were studied at different concentrations to optimize cadmium elution from orange or grapefruit peels. In most cases, desorption was fast, being over 90% complete within 50 min. However sodium nitrate and 0.001 M nitric acid were less efficient. Several new models for desorption kinetics were developed. While zero-, first- and second-order kinetics are commonly applied for modeling adsorption kinetics, the present study adapts these models to describe desorption kinetics. The proposed models relate to the number of metal-filled binding sites as the rate-determining reactant concentration. A model based on first order kinetics with respect to the remaining metal bound performed best. Cd bound in subsequent adsorption after desorption was similar to the original amount bound for desorption by

  12. Hand-held portable desorption atmospheric pressure chemical ionization ion source for in situ analysis of nitroaromatic explosives.

    Science.gov (United States)

    Jjunju, Fred P M; Maher, Simon; Li, Anyin; Syed, Sarfaraz U; Smith, Barry; Heeren, Ron M A; Taylor, Stephen; Cooks, R Graham

    2015-10-06

    A novel, lightweight (0.6 kg), solvent- and gas-cylinder-free, hand-held ion source based on desorption atmospheric pressure chemical ionization has been developed and deployed for the analysis of nitroaromatic explosives on surfaces in open air, offering portability for in-field analysis. A small, inexpensive, rechargeable lithium polymer battery was used to power the custom-designed circuitry within the device, which generates up to ±5 kV dc voltage to ignite a corona discharge plasma in air for up to 12 h of continuous operation, and allowing positive- and negative-ion mass spectrometry. The generated plasma is pneumatically transported to the surface to be interrogated by ambient air at a rate of 1-3.5 L/min, compressed using a small on-board diaphragm pump. The plasma source allows liquid or solid samples to be examined almost instantaneously without any sample preparation in the open environment. The advantages of low carrier gas and low power consumption (<6 W), as well as zero solvent usage, have aided in developing the field-ready, hand-held device for trigger-based, "near-real-time" sampling/ionization. Individual nitroaromatic explosives (such as 2,4,6-trinitrotoluene) can be easily detected in amounts as low as 5.8 pg with a linear dynamic range of at least 10 (10-100 pg), a relative standard deviation of ca. 7%, and an R(2) value of 0.9986. Direct detection of several nitroaromatic compounds in a complex mixture without prior sample preparation is demonstrated, and their identities are confirmed by tandem mass spectrometry fragmentation patterns.

  13. Evaluation of sorption-desorption processes for metalaxyl in natural and artificial soils.

    Science.gov (United States)

    Sukul, Premasis; Lamshöft, Marc; Zühlke, Sebastian; Spiteller, Michael

    2013-01-01

    The main process controlling soil-pesticide interaction is the sorption-desorption as influenced by active soil surfaces. The sorption phenomena can influence translocation, volatility, persistence and bioactivity of a pesticide in soil. The present investigation was conducted on natural and artificial soils in order to enumerate the effect of soil components such as montmorillonite and ferrihydrite on the sorption behaviour of the fungicide metalaxyl and if sorption-desorption of the chiral pesticide affects the enantiomeric ratio. The sorption-desorption characteristics of metalaxyl were investigated by batch equilibration technique in a natural soil, two artificial soils, and in pure montmorillonite and ferrihydrite. After extraction, pesticide residues were analyzed by conventional and chiral chromatography using tandem mass spectrometry. A KdSorp (2.3-6.5) suggests low level sorption of metalaxyl with an appreciable risk of run-off and leaching. Thus, metalaxyl poses a threat to surface and ground water contamination. Furthermore, desorption tests revealed a hysteretic effect (H ≤ 0.8) in natural and artificial soils. Significant amount of metalaxyl was found tightly bound to the adsorbents without desorbing readily after desorption cycle. Desorption of 22-56% of the total amount of the retained metalaxyl was determined. This study reveals that an artificial soil derived from different soil constituents can be used to assess their influence on sorption/desorption processes. The present investigation showed that both montmorillonite and ferrihydrite play a significant role in the sorption of metalaxyl. The sorption doesn't influence the enantiomeric ratio of racemic metalaxyl.

  14. Characteristics and influencing factors of tetrachloroethylene sorption-desorption on soil and its components.

    Science.gov (United States)

    Qiu, Zhaofu; Yang, Weiwei; He, Long; Zhao, Zhexuan; Lu, Shuguang; Sui, Qian

    2016-02-01

    To investigate the effects of soil structure, soil organic carbon (SOC), minerals, initial tetrachloroethylene (PCE) concentration (C0), and ionic strength (Ci) on PCE sorption-desorption, six types of soil were adopted as adsorbents, including two types of natural soil and four types of soil with most of the "soft carbon" pre-treated by H2O2 or with all SOC removed from the original soil by 600 °C ignition. The results showed that all of the sorption-desorption isotherms of PCE were non-linear within the experimental range, and the H2O2-treated samples exhibited higher non-linear sorption isotherms than those of the original soils. The hysteresis index of PCE sorption to original soil is less pronounced than that of the H2O2-treated and 600 °C-heated samples due to the entrapment of sorbate molecules in the "hard carbon" domain, together with the meso- and microporous structures within the 600 °C-heated samples. Both SOC and minerals have impacts on the sorption-desorption of PCE, and the sorption-desorption contribution rate of minerals increased with decreasing SOC content. C0 has almost no influence on the sorption to minerals of the soils, but the contribution rate of minerals decreased with increasing C0 in the desorption stage. As a result of the salting-out effect, PCE sorption capacity was increased by increasing Ci, especially when Ci ≥ 0.1 M. Moreover, desorption increased and hysteresis weakened with increasing Ci, except for the 600 °C-heated samples. In addition, no significant effect of Ci on desorption of PCE and no hysteresis was observed in this experimental range for the 600 °C-heated samples.

  15. 2,5-Dihydroxybenzoic acid: laser desorption/ionisation as a function of elevated temperature

    Science.gov (United States)

    Wallace, W. E.; Arnould, M. A.; Knochenmuss, R.

    2005-03-01

    The temperature dependence of laser desorption/ionization (LDI) ion yields has been measured for 2,5-dihydroxybenzoic acid (2,5-DHB) single crystals from room temperature to 160 °C using time-of-flight (TOF) mass spectrometry. A steep rise in ion production occurs at 90 °C, achieving a maximum at 120 °C, then decreases sharply to a minimum at 140 °C, and returns to a second maximum at 150 °C. Above 160 °C, useful information could not be obtained because of rapid volatilization of the sample into the vacuum. The overall trend in ion production, but not some of the details, is well described by a recent two-step theory of the laser desorption/ionization process, which takes into account the temperature-dependent effects of plume expansion. Measuring the background vacuum composition with a quadrupole mass spectrometer residual gas analyzer (RGA) showed an increase in thermal desorption of 2,5-DHB starting at 90 °C and maximizing at 130 °C. The increased neutral production by thermal desorption is believed to be the cause of the decrease in LDI ion production due to reduced pooling probabilities for laser-excited 2,5-DHB molecules. Thermal dehydration, condensation, and decarboxylation increase the volume of gas released at high temperatures which also serve to decrease LDI ion production at elevated temperatures. Lastly, to confirm the mass spectrometry results, the thermal desorption of 2,5-DHB single crystals under vacuum was measured using a quartz-crystal microbalance (QCM). The onset of desorption was found to occur at 90 °C and the maximum desorption rate was found at 135 °C.

  16. Surface and Particle-Size Effects on Hydrogen Desorption from Catalyst-Doped MgH2

    Energy Technology Data Exchange (ETDEWEB)

    Reich, J.M.; Wang, Lin-Lin; Johnson, Duane D.

    2012-09-04

    With their high capacity, light-metal hydrides like MgH2 remain under scrutiny as reversible H-storage materials, especially to develop control of H-desorption properties by decreasing size (ball-milling) and/or adding catalysts. By employing density functional theory and simulated annealing, we study initial H2 desorption from semi-infinite stepped rutile (110) surface and Mg31H62 nanoclusters, with(out) transition-metal catalyst dopants (Ti or Fe). While Mg31H62 structures are disordered (amorphous), the semi-infinite surfaces and nanoclusters have similar single, double, and triple H-to-metal bond configurations that yield similar H-desorption energies. Hence, there is no size effect on desorption energetics with reduction in sample size, but dopants do reduce the H-desorption energy. All desorption energies are endothermic, in contrast to a recent report.

  17. SORPTION AND DESORPTION OF GLYPHOSATE IN MOLLISOLS AND ULTISOLS SOILS OF ARGENTINA.

    Science.gov (United States)

    Gómez Ortiz, Ana Maria; Okada, Elena; Bedmar, Francisco; Costa, José Luis

    2017-05-08

    In Argentina, glyphosate use has increased exponentially in the past years due to the widespread adoption of no-till management combined with genetically modified glyphosate-resistant crops. This massive use of glyphosate has created concern about its potential environmental impact. Sorption-desorption of glyphosate was studied in three Argentinean soils with contrasting characteristics. Glyphosate sorption isotherms were modeled using the Freundlich equation to estimate the sorption coefficient (Kf ). Glyphosate sorption was high and the Kf varied from 115.6 to 1612 mg (1-1/n) L(1/n) /Kg. Cerro Azul soil had the highest glyphosate sorption capacity due to a combination of factors such as higher clay content, CEC, total Fe, Al oxides and lower available phosphorous and pH. Desorption isotherms were also modeled using the Freundlich equation. In general, desorption was very low (glyphosate strongly sorbs to the soils and that it is almost an irreversible process. Anguil soil had a significant higher desorption coefficient (Kfd ) than the other soils, associated with its lower clay content and higher pH and phosphorous. Glyphosate high sorption and low desorption to the studied soils may prevent groundwater contamination. However, it may also affect its bioavailability increasing its persistence and favoring its accumulation in environment. Results of this study contribute to the knowledge and characterization of glyphosate retention in different soils. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  18. Kinetic Modification on Hydrogen Desorption of Lithium Hydride and Magnesium Amide System

    Directory of Open Access Journals (Sweden)

    Hiroki Miyaoka

    2015-06-01

    Full Text Available Various synthesis and rehydrogenation processes of lithium hydride (LiH and magnesium amide (Mg(NH22 system with 8:3 molar ratio are investigated to understand the kinetic factors and effectively utilize the essential hydrogen desorption properties. For the hydrogen desorption with a solid-solid reaction, it is expected that the kinetic properties become worse by the sintering and phase separation. In fact, it is experimentally found that the low crystalline size and the close contact of LiH and Mg(NH22 lead to the fast hydrogen desorption. To preserve the potential hydrogen desorption properties, thermochemical and mechanochemical rehydrogenation processes are investigated. Although the only thermochemical process results in slowing the reaction rate due to the crystallization, the ball-milling can recover the original hydrogen desorption properties. Furthermore, the mechanochemical process at 150 °C is useful as the rehydrogenation technique to preserve the suitable crystalline size and mixing state of the reactants. As a result, it is demonstrated that the 8LiH and 3Mg(NH22 system is recognized as the potential hydrogen storage material to desorb more than 5.5 mass% of H2 at 150 °C.

  19. Kinetic Modification on Hydrogen Desorption of Lithium Hydride and Magnesium Amide System.

    Science.gov (United States)

    Miyaoka, Hiroki; Wang, Yongming; Hino, Satoshi; Isobe, Shigehito; Tokoyoda, Kazuhiko; Ichikawa, Takayuki; Kojima, Yoshitsugu

    2015-06-29

    Various synthesis and rehydrogenation processes of lithium hydride (LiH) and magnesium amide (Mg(NH₂)₂) system with 8:3 molar ratio are investigated to understand the kinetic factors and effectively utilize the essential hydrogen desorption properties. For the hydrogen desorption with a solid-solid reaction, it is expected that the kinetic properties become worse by the sintering and phase separation. In fact, it is experimentally found that the low crystalline size and the close contact of LiH and Mg(NH₂)₂ lead to the fast hydrogen desorption. To preserve the potential hydrogen desorption properties, thermochemical and mechanochemical rehydrogenation processes are investigated. Although the only thermochemical process results in slowing the reaction rate due to the crystallization, the ball-milling can recover the original hydrogen desorption properties. Furthermore, the mechanochemical process at 150 °C is useful as the rehydrogenation technique to preserve the suitable crystalline size and mixing state of the reactants. As a result, it is demonstrated that the 8LiH and 3Mg(NH₂)₂ system is recognized as the potential hydrogen storage material to desorb more than 5.5 mass% of H₂ at 150 °C.

  20. Hydrogen desorption properties of magnesium hydride catalyzed multiply with carbon and silicon

    Energy Technology Data Exchange (ETDEWEB)

    Klimkowicz, Alicja [AGH University of Science and Technology Faculty of Energy and Fuels, al. A. Mickiewicza 30, 30-059 Krakow (Poland); Shibaura Institute of Technology, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku 135-8548, Tokyo (Japan); Takasaki, Akito, E-mail: takasaki@sic.shibaura-it.ac.jp [Shibaura Institute of Technology, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku 135-8548, Tokyo (Japan); Gondek, Łukasz; Figiel, Henryk [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. A. Mickiewicza 30, 30-059 Krakow (Poland); Świerczek, Konrad [AGH University of Science and Technology Faculty of Energy and Fuels, al. A. Mickiewicza 30, 30-059 Krakow (Poland)

    2015-10-05

    Highlights: • Crystal structure of 2 mol MgH{sub 2} + (1 − X) mol C + X mol Si (for X = 0, 0.25, 0.5, 0.75 and 1). • Enhanced hydrogen desorption properties. • Lowered temperature of hydrogen desorption for MgH{sub 2} with the multiple addition of C and Si. • Distribution of Si and C on MgH{sub 2} particles after mechanical milling. - Abstract: Magnesium hydride (MgH{sub 2}) is considered as one of hydrogen storage materials. However, the application is limited because of slow hydrogen kinetics and high thermodynamic stability. In this study, MgH{sub 2} powders were mechanically milled with graphite (C) and/or silicon (Si) powders, and effect of multiple addition of C and Si on hydrogen desorption properties was investigated. The multiple addition caused a decrease of the hydrogen desorption (onset and peak) temperatures more than single addition, and the lowest activation energy for hydrogen desorption, 62 kJ/mol, was obtained from sample powders of (2 mol MgH{sub 2} + 0.5 mol C + 0.5 mol Si). The surface of the sample powders after mechanical milling revealed a good distribution of C on the MgH{sub 2} surface and a presence of finer Si particles.

  1. Long-term tillage effects on soil metolachlor sorption and desorption behavior.

    Science.gov (United States)

    Ding, Guangwei; Novak, Jeffrey M; Herbert, Stephen; Xing, Baoshan

    2002-09-01

    Sorption and desorption are two important processes that influence the amount of pesticides retained by soils. However, the detailed sorption mechanisms as influenced by soil tillage management are unclear. This study examined the sorption and desorption characteristics of metolachlor [2-chloro-N-(2-ethyl-6-methyphenyl)-N-(2-methoxy-1-methylethyl)-acetamide] using the soil samples collected from the long-term conservation tillage (CnT) and conventional tillage (CT) research plots established in 1979 in Darlinton, SC. Humic acid (HA) and humin were extracted from the soils and used in the sorption experiments along with the whole soil samples. The sorption experiments were conducted using a batch-equilibration method. Three sequential desorption rinses were carried out following the sorption experiments. By comparing metolachlor sorption and desorption results we observed hysteresis for all soil samples and their organic matter fractions. Sorption nonlinearity (N) and hysteresis were dependent on the structure and composition of soil organic matter (SOM), e.g., Freundlich isotherm exponents (N) of HA and humin from CnT were higher than those of CT treatment, which may be related to high aromaticity of SOM fractions in CT treatment. Sorption capacity (K'f) was positively correlated with soil organic carbon (SOC) content. These results show that long-term tillage management can greatly affect metolachlor sorption and desorption behavior probably by qualitative differences in the structural characteristics of the humic substances.

  2. Adsorption and Desorption of Ammonium in Wetland Soils Subject to Freeze-Thaw Cycles

    Institute of Scientific and Technical Information of China (English)

    YU Xiao-Fei; ZHANG Yu-Xia; ZOU Yuan-Chun; ZHAO Hong-Mei; LU Xian-Guo; WANG Guo-Ping

    2011-01-01

    Nitrogen (N) cycling in boreal peatland ecosystems may be influenced in important ways by freeze-thaw cycles (FTCs). Adsorption and desorption of ammonium ions (NH4+) were examined in a controlled laboratory experiment for soils sampled from palustrine wetland, riverine wetland, and farmland reclaimed from natural wetland in response to the number of FTCs. The results indicate that freeze-thaw significantly increased the adsorption capacity of NH4+ and reduced the desorption potential of NH4+ in the wetland soils. There were significant differences in the NH4+ adsorption amount between the soils with and without freeze-thaw treatment.The adsorption amount of NH4+ increased with increasing FTCs. The palustrine wetland soil had a greater adsorption capacity and a weaker desorption potential of NH4+ than the riverine wetland soil because of the significantly higher clay content and cation exchange capacity (CEC) of the riverine wetland soil. Because of the altered soil physical and chemical properties and hydroperiods, the adsorption capacity of NH4+ was smaller in the farmland soil than in the wetland soils, while the desorption potential of the farmland soil was higher than that of the wetland soils. Thus, wetland reclamation would decrease adsorption capacity and increase desorption potential of NH4+, which could result in N loss from the farmland soil. FTCs might mitigate N loss from soils and reduce the risk of water pollution in downstream ecosystems.

  3. The impact of vegetation on sedimentary organic matter composition and PAH desorption

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, Elizabeth Guthrie [North Carolina State University, Department of Forestry and Environmental Resources, 2800 Faucette Drive, Raleigh, NC 27695 (United States)], E-mail: elizabeth_nichols@ncsu.edu; Gregory, Samuel T.; Musella, Jennifer S. [North Carolina State University, Department of Forestry and Environmental Resources, 2800 Faucette Drive, Raleigh, NC 27695 (United States)

    2008-12-15

    Relationships between sedimentary organic matter (SOM) composition and PAH desorption behavior were determined for vegetated and non-vegetated refinery distillate waste sediments. Sediments were fractionated into size, density, and humin fractions and analyzed for their organic matter content. Bulk sediment and humin fractions differed more in organic matter composition than size/density fractions. Vegetated humin and bulk sediments contained more polar organic carbon, black carbon, and modern (plant) carbon than non-vegetated sediment fractions. Desorption kinetics of phenanthrene, pyrene, chrysene, and C{sub 3}-phenanthrene/anthracenes from humin and bulk sediments were investigated using Tenax beads and a two-compartment, first-order kinetic model. PAH desorption from distillate waste sediments appeared to be controlled by the slow desorbing fractions of sediment; rate constants were similar to literature values for k{sub slow} and k{sub veryslow}. After several decades of plant colonization and growth (Phragmites australis), vegetated sediment fractions more extensively desorbed PAHs and had faster desorption kinetics than non-vegetated sediment fractions. - Plants alter sediment organic matter composition and PAH desorption behavior.

  4. [Sorption and desorption of phenanthrene by organo-mineral complexes with different bridge cations].

    Science.gov (United States)

    Ni, Jin-zhi; Luo, Yong-ming; Wei, Ran; Li, Xiu-hua; Qian, Wei

    2008-12-01

    Sorption and desorption of phenanthrene by organo-mineral complexes with Ca2+, Fe3+ and Al3+ as bridge cations were studied according to the association type between organic matter and minerals in natural soils. The results showed that the data of phenanthrene sorption and desorption by different cation saturated montmorillonite and their corresponding humic acid and mineral complexes could be fitted with Freundlich model, and the order of the sorption capacities (Kf) were Ca-Mont (0.184) > Fe-Mont (0.028) > Al-Mont (0.015) and Fe-Mont-HA (2.341) > Ca-Mont-HA (1.557) > Al-Mont-HA (1.136), respectively. The Kf values of humic acid and mineral complexes were far greater than those of minerals, which demonstrated that humic acid made great contributions to the sorption of phenanthrene in the organo-mineral complexes. However, the Kf values of the organo-mineral complexes with different bridge cations were not consistent with their organic carbon content, which indicated that both the organic carbon content and the combined types between organic matter and mineral could affect the sorption capacity of phenanthrene by the organo-mineral complexes. The desorption hysteresis of phenanthrene was significant for Ca2+ and Al3+ bridged organo-mineral complexes. Desorption hysteresis of phenanthrene was mainly from the sorption of phenanthrene by organic matter, and the contributions of mineral to the desorption hysteresis were not significant.

  5. Freeze-thaw Effects on Sorption/Desorption of Dissolved Organic Carbon in Wetland Soils

    Institute of Scientific and Technical Information of China (English)

    YU Xiaofei; ZHANG Yuxia; ZHAO Hongmei; LU Xianguo; WANG Guoping

    2010-01-01

    The effects of freeze-thaw cycles on sorption/desorption of dissolved organic carbon (DOC) in two wetland soils and one reclaimed wetland soil were investigated. DOC concentrations added were 0-600 mg/L. Laboratory in-cubations of sorption/desorption of DOC had been carried out at -15℃ for 10 h, and then at +5℃ for 13 h. Soil sam-ples were refrozen and thawed subsequently for 5 cycles. Initial Mass model was used to describe sorption behavior of DOC. The results indicate that freeze-thaw cycles can significantly increase the sorption capacity of DOC and reduce the desorption capacity of DOC in the three soils. The freeze-thaw effects on desorption of DOC in soils increase with the increasing freeze-thaw cycles. The conversion of natural wetlands to soybean farmland can decrease the sorption capacity and increase the desorption capacity of DOC in soils. Global wanning and reclamation may increase DOC re-lease, and subsequently increase the loss of carbon and the emission of greenhouse gas.

  6. Ion desorption from frozen H 2O irradiated by MeV heavy ions

    Science.gov (United States)

    Collado, V. M.; Farenzena, L. S.; Ponciano, C. R.; Silveira, E. F. da; Wien, K.

    2004-10-01

    Nitrogen (0.13-0.85 MeV) and 252Cf fission fragments (˜65 MeV) beams are employed to sputter positive and negative secondary ions from frozen water. Desorption yields are measured for different ice temperatures and projectile energies. Target surface is continuously refreshed by condensed water while the target temperature varies and ice thickness changes. In both projectile energy ranges, the preferentially ejected ions are H +, H2+ and (H 2O) nH +-cluster ions. The yields of the corresponding negative ions H - and (H 2O) nO - or (H 2O) nOH - are 1-2 orders of magnitude lower. The (H 2O) nH + desorption yields decrease exponentially as the cluster size, n, increases. In the low energy range, the desorption of positive ion clusters may occur in a two-step process: first, desorption of preformed H 2O clusters and, then, ionization by H + or H 3O + capture. For 0.81 MeV N + projectile ions, the cluster ion emission contributes with 0.05% to the total H 2O desorbed yield. There are indications that emission of the (H 2O) nH + disappears for an electronic energy loss lower than 20 eV/Å. For the high energy range, desorption of small ion clusters is particularly enhanced, revealing that a fragmentation process also exists.

  7. Improvement of the LiBH{sub 4} hydrogen desorption by confinement in modified carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.T.; Wan, C.B.; Meng, X.H.; Ju, X., E-mail: jux@ustb.edu.cn

    2015-10-05

    Highlights: • The desorption kinetics for LiBH{sub 4} greatly promoted using melt infiltration method. • The LiBH{sub 4} confined in modified MWCNTs shows the best desorption kinetics. • The crystal structure of MWCNTs and SWCNTs is unchanged after ball milling. • Ball milling introduces a great amount of structural defects in the CNTs. • Nano-confinement is dominant on improving the hydrogen desorption of LiBH{sub 4}. - Abstract: The dehydrogenation kinetics of LiBH{sub 4} incorporated within various carbon nanotubes has been studied. It is demonstrated that the desorption kinetics of LiBH{sub 4} could be greatly promoted using a simple melt infiltration method and LiBH{sub 4} confined in modified multi-walled carbon nanotubes (MWCNTs) shows the best desorption kinetics. The structural properties of carbon nanotubes and confined samples are demonstrated by means of transmission electron microscopy, powder X-ray diffraction and Raman spectroscopy. The crystal structure of MWCNTs and single-walled carbon nanotubes (SWCNTs) are almost unchanged after ball milling. But high energy ball milling leads to a decrease in the average nanotube length and introduces a great amount of local disorder and structural defects in the CNTs, which may provide a considerable kinetic improvement.

  8. Adsorption and desorption of herbicide monosulfuron-ester in Chinese soils

    Institute of Scientific and Technical Information of China (English)

    Chunxian Wu; Suzhi Zhang; Guo Nie; Zhongming Zhang; Jinjun Wang

    2011-01-01

    Monosulfuron-ester is a new,low rate,sulfonylurea herbicide that is being promoted for annual broadleaf and gramineal weed control; however,there is a lack of published information on its behavior in soils.The adsorption and desorption of monosulfuronester by seven type soils were measured using a batch equilibrium technique.The results showed that the Freundlich equation fitted its adsorption and desorption well,and the Freundlich constant values (Kf-~) ranged from 0.88 to 5.66.Adsorption isotherms were nonlinear with l/nf-ads values < 1.Soil pH,organic matter (OM),and clay content were the main factors influencing its adsorption and desorption.Adsorption and desorption were negatively correlated with pH 4.0-8.0 while positively correlated with OM and clay content.The adsorption of monosulfuron-ester was mainly a physical process,because its free energy (ΔG) in seven soils was less than 40 kJ/mol.Monosulfuron-ester adsorption by three soils increased with increasing CaCl2 concentration using CaCl2 as a background electrolyte.Monosulfuron-ester desorption was hysteretic in all tested soils.

  9. GaN CVD Reactions: Hydrogen and Ammonia Decomposition and the Desorption of Gallium

    Energy Technology Data Exchange (ETDEWEB)

    Bartram, Michael E.; Creighton, J. Randall

    1999-05-26

    Isotopic labeling experiments have revealed correlations between hydrogen reactions, Ga desorption, and ammonia decomposition in GaN CVD. Low energy electron diffraction (LEED) and temperature programmed desorption (TPD) were used to demonstrate that hydrogen atoms are available on the surface for reaction after exposing GaN(0001) to deuterium at elevated temperatures. Hydrogen reactions also lowered the temperature for Ga desorption significantly. Ammonia did not decompose on the surface before hydrogen exposure. However, after hydrogen reactions altered the surface, N15H3 did undergo both reversible and irreversible decomposition. This also resulted in the desorption of N2 of mixed isotopes below the onset of GaN sublimation, This suggests that the driving force of the high nitrogen-nitrogen bond strength (226 kcal/mol) can lead to the removal of nitrogen from the substrate when the surface is nitrogen rich. Overall, these findings indicate that hydrogen can influence G-aN CVD significantly, being a common factor in the reactivity of the surface, the desorption of Ga, and the decomposition of ammonia.

  10. Surface-assisted laser desorption ionization mass spectrometry techniques for application in forensics.

    Science.gov (United States)

    Guinan, Taryn; Kirkbride, Paul; Pigou, Paul E; Ronci, Maurizio; Kobus, Hilton; Voelcker, Nicolas H

    2015-01-01

    Matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) is an excellent analytical technique for the rapid and sensitive analysis of macromolecules (>700 Da), such as peptides, proteins, nucleic acids, and synthetic polymers. However, the detection of smaller organic molecules with masses below 700 Da using MALDI-MS is challenging due to the appearance of matrix adducts and matrix fragment peaks in the same spectral range. Recently, nanostructured substrates have been developed that facilitate matrix-free laser desorption ionization (LDI), contributing to an emerging analytical paradigm referred to as surface-assisted laser desorption ionization (SALDI) MS. Since SALDI enables the detection of small organic molecules, it is rapidly growing in popularity, including in the field of forensics. At the same time, SALDI also holds significant potential as a high throughput analytical tool in roadside, work place and athlete drug testing. In this review, we discuss recent advances in SALDI techniques such as desorption ionization on porous silicon (DIOS), nano-initiator mass spectrometry (NIMS) and nano assisted laser desorption ionization (NALDI™) and compare their strengths and weaknesses with particular focus on forensic applications. These include the detection of illicit drug molecules and their metabolites in biological matrices and small molecule detection from forensic samples including banknotes and fingerprints. Finally, the review highlights recent advances in mass spectrometry imaging (MSI) using SALDI techniques.

  11. On the Formation of Nanobubbles in Vycor Porous Glass during the Desorption of Halogenated Hydrocarbons

    Science.gov (United States)

    Mitropoulos, A. C.; Stefanopoulos, K. L.; Favvas, E. P.; Vansant, E.; Hankins, N. P.

    2015-06-01

    Vycor porous glass has long served as a model mesoporous material. During the physical adsorption of halogenated hydrocarbon vapours, such as dibromomethane, the adsorption isotherm exhibits an hysteresis loop; a gradual ascent is observed at higher pressures during adsorption, and a sharp drop is observed at lower pressures during desorption. For fully wetting fluids, an early hypothesis attributed the hysteresis to mechanistic differences between capillary condensation (adsorption) and evaporation (desorption) processes occurring in the wide bodies and narrow necks, respectively, of ‘ink-bottle’ pores. This was later recognized as oversimplified when the role of network percolation was included. For the first time, we present in-situ small angle x-ray scattering measurements on the hysteresis effect which indicate nanobubble formation during desorption, and support an extended picture of network percolation. The desorption pattern can indeed result from network percolation; but this can sometimes be initiated by a local cavitation process without pore blocking, which is preceded by the temporary, heterogeneous formation of nanobubbles involving a change in wetting states. The capacity of the system to sustain such metastable states is governed by the steepness of the desorption boundary.

  12. The Adsorption and Desorption of Pb(2+) and Cd(2+) in Freeze-Thaw Treated Soils.

    Science.gov (United States)

    Li, Linhui; Ma, Jincai; Xu, Meng; Li, Xu; Tao, Jiahui; Wang, Guanzhu; Yu, Jitong; Guo, Ping

    2016-01-01

    Adsorption and desorption are important processes that influence the potential toxicity and bioavailability of heavy metals in soils. However, information regarding adsorption and desorption behavior of heavy metals in soils subjected to freeze-thaw cycles is poorly understood. In the current study, the effect of freeze-thaw cycles with different freezing temperature (-15, -25, -35°C) on soil properties was investigated. Then the adsorption and desorption behavior of Pb(2+) and Cd(2+) in freeze-thaw treated soils was studied. The adsorption amounts of Pb(2+) and Cd(2+) in freeze-thaw treated soils were smaller than those in unfrozen soils (p adsorption amounts of Pb(2+) and Cd(2+) in soils treated with lower freezing temperatures were higher than those in soils treated with higher freezing temperatures. Desorption percentages of Pb(2+) and Cd(2+) in unfrozen soils were smaller than those in freeze-thaw treated soils (p adsorption and desorption behavior of typical heavy metals in freeze-thaw treated soils located in seasonal frozen soils zone in northeast China.

  13. Temperature programmed desorption of CO from CO pre-covered Mo(1 1 0)

    Energy Technology Data Exchange (ETDEWEB)

    Raaen, Steinar, E-mail: sraaen@ntnu.no [Physics Department, Norwegian University of Science and Technology, NTNU, 7491 Trondheim (Norway); Yu, Xiaofeng [Seksjon for naturfag, Høgskolen i Nesna, 8700 Nesna (Norway)

    2015-09-15

    Highlights: • Desorption of CO from CO pre-covered Mo(1 1 0) is investigated. • Large variations in CO desorption spectra are observed. • Multiple adsorption sites are available on the surface. • Lateral interaction between adsorbed molecules is important. - Abstract: Adsorption and desorption of CO on clean and CO pre-covered Mo(1 1 0) have been studied by temperature programmed desorption (TPD), low energy electron diffraction, X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. It was found that adsorption and subsequent desorption of CO from Mo(1 1 0) and CO pre-covered Mo(1 1 0) show large differences in the TPD spectra in the low temperature region from 150 to 400 K. In the case of the pre-covered sample a dramatically increased width to lower temperatures was observed. The increased width at higher CO coverage is argued to result from a distribution of adsorption sites and increased lateral interactions between adsorbed CO molecules.

  14. Effect of Dissolved Organic Matter on Chlorotoluron Sorption and Desorption in Soils

    Institute of Scientific and Technical Information of China (English)

    YANG Hong; WU Xin; ZHOU Li-Xiang; YANG Zhi-Min

    2005-01-01

    A batch equilibrium techniques was used to examine the effect of dissolved organic matter (DOM) extracted from both non-treated sludge (NTS) and heat-expanded sludge (HES) on the sorption and desorption of chlorotoluron (3-(3-chloro-p-tolyl)-1,1-dimethylurea) in two types of soils, a yellow fluvo-aquic and a red soil from China. Without DOM,sorption of chlorotoluron was significantly greater (P < 0.05) in the red soil than in the yellow fluvo-aquic soil. However,with DOM the effect was dependent on the soil type and nature of DOM. Chlorotoluron sorption was lower in the yellow fluvo-aquic soil than in the red soil, suggesting that with the same DOM levels the yellow fluvo-aquic soil had a lower sorption capacity for this herbicide. Application of DOM from both NTS and HES led to a general decrease in sorption to the soils and an increase in desorption from the soils. Desorption of chlorotoluron also significantly increased (P < 0.05)with an increase in the DOM concentration. Additionally, for sorption and desorption, at each DOM treatment level the NTS treatments were significantly lower (P < 0.05) than the HES treatments. This implied that non-treated sludge had a greater effect on the sorption and desorption of chlorotoluron than heat-expanded sludge.

  15. Plasma chromograninx

    DEFF Research Database (Denmark)

    Goetze, Jens P; Hilsted, Linda M; Rehfeld, Jens F

    2014-01-01

    Cardiovascular risk assessment remains difficult in elderly patients. We examined whether chromogranin A (CgA) measurement in plasma may be valuable in assessing risk of death in elderly patients with symptoms of heart failure in a primary care setting. A total of 470 patients (mean age 73 years......) were followed for 10 years. For CgA plasma measurement, we used a two-step method including a screening test and a confirmative test with plasma pre-treatment with trypsin. Cox multivariable proportional regression and receiver-operating curve (ROC) analyses were used to assess mortality risk...... of follow-up showed significant additive value of CgA confirm measurements compared with NT-proBNP and clinical variables. CgA measurement in the plasma of elderly patients with symptoms of heart failure can identify those at increased risk of short- and long-term mortality....

  16. Plasma Cleaning

    Science.gov (United States)

    Hintze, Paul E.

    2016-01-01

    NASA's Kennedy Space Center has developed two solvent-free precision cleaning techniques: plasma cleaning and supercritical carbon dioxide (SCCO2), that has equal performance, cost parity, and no environmental liability, as compared to existing solvent cleaning methods.

  17. Plasma confinement

    CERN Document Server

    Hazeltine, R D

    2003-01-01

    Detailed and authoritative, this volume examines the essential physics underlying international research in magnetic confinement fusion. It offers readable, thorough accounts of the fundamental concepts behind methods of confining plasma at or near thermonuclear conditions. Designed for a one- or two-semester graduate-level course in plasma physics, it also represents a valuable reference for professional physicists in controlled fusion and related disciplines.

  18. A new ultrafast and high-throughput mass spectrometric approach for the therapeutic drug monitoring of the multi-targeted anti-folate pemetrexed in plasma from lung cancer patients

    NARCIS (Netherlands)

    R.J.W. Meesters (Roland); R. Cornelissen (Robin); R.J. van Klaveren (Rob); R. de Jonge (Robert); E. den Boer (Ethan); J. Lindemans (Jan); T.M. Luider (Theo)

    2010-01-01

    textabstractAn analytical assay has been developed and validated for ultrafast and high-throughput mass spectrometric determination of pemetrexed concentrations in plasma using matrix assisted laser desorption/ionization-triple quadrupole-tandem mass spectrometry. Patient plasma samples spiked with

  19. Direct pathway for sticking/desorption of H2 on Si(100)

    DEFF Research Database (Denmark)

    Kratzer, Peter; Hammer, Bjørk; Nørskov, Jens Kehlet

    1995-01-01

    The energetics of H2 interacting with the Si(100) surface is studied by means of ab initio total-energy calculations within the framework of density-functional theory. We find a direct desorption pathway from the monohydride phase that is compatible with experimental activation energies and demon...... influence on the surface electronic structure. We discuss the consequences of this coupling for adsorption experiments and the relation between adsorption and desorption.......The energetics of H2 interacting with the Si(100) surface is studied by means of ab initio total-energy calculations within the framework of density-functional theory. We find a direct desorption pathway from the monohydride phase that is compatible with experimental activation energies...

  20. Dynamic and static adsorption and desorption of Hg(II) ions on chitosan membranes and spheres.

    Science.gov (United States)

    Vieira, Rodrigo S; Beppu, Marisa M

    2006-05-01

    The adsorption and desorption of Hg(II) ions was studied using static and dynamic methods, employing membranes and spheres of chitosan as the adsorbent. The quantity of adsorption was influenced by chitosan crosslinking and by the adsorbent shape. The Langmuir model was applied to fit the experimental equilibrium data. Glutaraldehyde-crosslinked membranes presented a lower desorption capacity, when compared to natural membranes, but could be regenerated for use in successive cycles. Dynamic adsorption experiments suggested that the adsorption capacity depended mainly on adsorbent geometry, due to differences between surface area to mass ratio and initial concentration of Hg(II) ions. The adsorption capacity determined by the dynamic method was 65% and 77% for membranes and spheres, respectively of the value obtained static method results. A process combining dynamic adsorption and static desorption can be used to concentrate the Hg(II) ions by a factor of nearly seven (7x), when compared to the initially treated volume.

  1. Activation energy of thermal desorption of silicon oxide layers on silicon substrates

    Science.gov (United States)

    Enta, Yoshiharu; Osanai, Shodai; Ogasawara, Takahito

    2017-02-01

    Thermal desorption rates of silicon oxide layers, from 20 to 120 nm in thickness, on silicon substrates in vacuum have been accurately obtained from intervals between ring structures formed inside voids on the oxide layers. From the temperature dependence of the desorption rate, the activation energy and frequency factor of the desorption reaction have been derived as a function of the oxide thickness. The obtained values are compared with the previous studies, and as a result, the activation energy is found to be almost constant ( 4 eV) in a wide range of the oxide thickness. The frequency factor decreases as the inverse square of the oxide thickness. The decomposition kinetics of the oxide layer is also discussed from the obtained results.

  2. Adsorption and desorption behavior of metalaxyl in intensively cultivated acid soils.

    Science.gov (United States)

    Bermudez-Couso, Alipio; Fernandez-Calvino, David; Pateiro-Moure, Miriam; Garrido-Rodriguez, Beatriz; Novoa-Munoz, Juan Carlos; Estevez, Manuel Arias

    2011-07-13

    Metalaxyl adsorption and desorption behavior in acid soils were evaluated via batch and stirred-flow chamber experiments. On the basis of batch experiments (adsorption curves of the Giles C-type), metalaxyl has a low affinity for acid soils. Also, as derived from batch and stirred-flow chamber tests, its adsorption in acid soils is dictated mainly by their organic matter and clay contents. The high correlation between these two variables makes it rather complicated to resolve their effects. Metalaxyl adsorption occurs largely (80-99%) via fast adsorption reactions. On the other hand, the pesticide is desorbed in variable proportions (30-100%). The desorption parameters obtained by fitting the results to a pseudo-first-order reaction were correlated with no edaphic variable; however, the q(0)/q(max) ratio, which is a measure of reversibility in the adsorption-desorption process, exhibited significant negative correlation with the organic matter and clay contents.

  3. Non-isothermal kinetics of the thermal desorption of mercury from a contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, F. A.; Sierra, M. J.; Rodriguez, O.; Millan, R.; Alguacil, F. J.

    2014-04-01

    The Almaden mining district (Ciudad Real, Spain) was the largest cinnabar (mercury sulphide) mine in the world. Its soils have high levels of mercury a consequence of its natural lithology, but often made much worse by its mining history. The present work examines the thermal desorption of two contaminated soils from the Almaden area under non-isothermal conditions in a N{sub 2} atmosphere, using differential scanning calorimetry (DSC). DSC was performed at different heating rates between room temperature and 600 degree centigrade. Desorption temperatures for different mercury species were determined. The Friedman, Flynn-Wall-Ozawa and Coasts Redfern methods were employed to determine the reaction kinetics from the DSC data. The activation energy and pre-exponential factor for mercury desorption were calculated. (Author)

  4. Incorporating sorption/desorption of organic pollutants into river water quality model

    Institute of Scientific and Technical Information of China (English)

    LOU Bao-feng; ZHU Li-zhong; YANG Kun

    2004-01-01

    Preliminary research was conducted about how to incorporate sorption/desorption of organic pollutants with suspended solids and sediments into single-chemical and one-dimensional water quality model of Jinghang Canal.Sedimentation-resuspension coefficient k3 was deduced; characteristics of organic pollutants, concentrations and components of suspended solids/sediments and hydrological and hydraulic conditions were integrated into k3 and further into river water quality model; impact of sorption/desorption of organic pollutants with suspended solids and sediments on prediction function of the model was discussed. Results demonstrated that this impact is pronounced for organic pollutants with relatively large Koc and Kow, especially when they are also conservative and foc of river suspended solids/sediments is high, and that incorporation of sorption/ desorption of organic pollutants into river water quality model can improve its prediction accuracy.

  5. WATER ADSORPTION AND DESORPTION ISOTHERMS ON MILK POWDER: II. WHOLE MILK

    Directory of Open Access Journals (Sweden)

    Edgar M. Soteras

    2014-03-01

    Full Text Available The aim of this research was the determination of adsorption and desorption isotherms of cow whole milk powder. The experiments have been carried out at 15, 25 and 40 ºC, in ranges of moisture and water activity characteristic of normal conditions in which the processes of drying, packaging and storage are developed. By studying the influence of the temperature on the experimental plots, the isosteric adsorption heat was determined. Experimental data were correlated to the referential model of Guggenheim, Anderson and Boer (GAB. For both, adsorption and desorption, a good model fit was observed. The isotherms showed very similar shapes between them and, by comparing adsorption and desorption isotherms, the phenomenon of hysteresis was confirmed.

  6. Adsorption and desorption of herbicide monosulfuron-ester in Chinese soils.

    Science.gov (United States)

    Wu, Chunxian; Zhang, Suzhi; Nie, Guo; Zhang, Zhongming; Wang, Jinjun

    2011-01-01

    Monosulfuron-ester is a new, low rate, sulfonylurea herbicide that is being promoted for annual broadleaf and gramineal weed control; however, there is a lack of published information on its behavior in soils. The adsorption and desorption of monosulfuron-ester by seven type soils were measured using a batch equilibrium technique. The results showed that the Freundlich equation fitted its adsorption and desorption well, and the Freundlich constant values (K(f-ads)) ranged from 0.88 to 5.66. Adsorption isotherms were nonlinear with 1/n(f-ads) values monosulfuron-ester was mainly a physical process, because its free energy (deltaG) in seven soils was less than 40 kJ/mol. Monosulfuron-ester adsorption by three soils increased with increasing CaCl2 concentration using CaCl2 as a background electrolyte. Monosulfuron-ester desorption was hysteretic in all tested soils.

  7. Laser-Induced Acoustic Desorption Atmospheric Pressure Photoionization via VUV-Generating Microplasmas.

    Science.gov (United States)

    Benham, Kevin; Hodyss, Robert; Fernández, Facundo M; Orlando, Thomas M

    2016-11-01

    We demonstrate the first application of laser-induced acoustic desorption (LIAD) and atmospheric pressure photoionization (APPI) as a mass spectrometric method for detecting low-polarity organics. This was accomplished using a Lyman-α (10.2 eV) photon generating microhollow cathode discharge (MHCD) microplasma photon source in conjunction with the addition of a gas-phase molecular dopant. This combination provided a soft desorption and a relatively soft ionization technique. Selected compounds analyzed include α-tocopherol, perylene, cholesterol, phenanthrene, phylloquinone, and squalene. Detectable surface concentrations as low as a few pmol per spot sampled were achievable using test molecules. The combination of LIAD and APPI provided a soft desorption and ionization technique that can allow detection of labile, low-polarity, structurally complex molecules over a wide mass range with minimal fragmentation. Graphical Abstract ᅟ.

  8. Biosorption and desorption of Cd2+ from wastewater by dehydrated shreds of Cladophora fascicularis

    Institute of Scientific and Technical Information of China (English)

    DENG Liping; ZHU Xiaobin; SU Yingying; SU Hua; WANG Xinting

    2008-01-01

    The adsorption and desorption of algae Cladophora fascicularis and their relation with initial Cd2+ concentration,initial pH,and co-existing ions were studied.Adsorption equilibrium and biosorption kinetics were established from batch experiments.The adsorption equilibrium was adequately described by the Langmuir isotherm,and biosorption kinetics was in pseudo-second order model.The experiment on co-existing ions showed that the biosorption capacity of biomass decreased with an increasing concentration of competing ions.Desorption experiments indicated that EDTA was efficient desorbent for recovery from Cd2+.With high capacities of metal biosorption and desorption,the biomass of Cladophora fascicularis is promising as a cost-effective biosorbent for the removal of Cd2+ from wastewater.

  9. Laser-Induced Acoustic Desorption Atmospheric Pressure Photoionization via VUV-Generating Microplasmas

    Science.gov (United States)

    Benham, Kevin; Hodyss, Robert; Fernández, Facundo M.; Orlando, Thomas M.

    2016-11-01

    We demonstrate the first application of laser-induced acoustic desorption (LIAD) and atmospheric pressure photoionization (APPI) as a mass spectrometric method for detecting low-polarity organics. This was accomplished using a Lyman-α (10.2 eV) photon generating microhollow cathode discharge (MHCD) microplasma photon source in conjunction with the addition of a gas-phase molecular dopant. This combination provided a soft desorption and a relatively soft ionization technique. Selected compounds analyzed include α-tocopherol, perylene, cholesterol, phenanthrene, phylloquinone, and squalene. Detectable surface concentrations as low as a few pmol per spot sampled were achievable using test molecules. The combination of LIAD and APPI provided a soft desorption and ionization technique that can allow detection of labile, low-polarity, structurally complex molecules over a wide mass range with minimal fragmentation.

  10. Desorption of Furfural from Bimetallic Pt-Fe Oxides/Alumina Catalysts

    Directory of Open Access Journals (Sweden)

    Gloria Lourdes Dimas-Rivera

    2014-01-01

    Full Text Available In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA. The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM imaging revealed the intimate connection between the iron and platinum oxide species on the alumina support. The mechanism of furfural desorption from the Pt-Fe/Al2O3 0.5%-0.5% sample was determined using physisorbed furfural instead of chemisorbed furfural; this mechanism involved the oxidation of the C=O group on furfural by the catalyst. The oxide nanoparticles on γ-Al2O3 support helped to stabilize the furfural molecule on the surface.

  11. Competitive sorption-desorption behavior of triazine herbicides with plant cuticular fractions.

    Science.gov (United States)

    Shechter, Michal; Xing, Baoshan; Kopinke, Frank-Dieter; Chefetz, Benny

    2006-10-04

    Sorption interactions of plant cuticular matter with organic compounds are not yet fully understood. The objective of this study was to examine the competitive sorption-desorption interactions of the triazine herbicides (atrazine and ametryn) with cuticular fractions isolated from tomato fruits and leaves of Agave americana. The 13C NMR data suggest a rubber-like nature for the cutin. This biopolymer exhibited reversible and noncompetitive sorption. Enhanced desorption of atrazine was recorded in the bi-solute system with bulk and dewaxed A. americana cuticles. 13C NMR analyses of these samples suggested that the sorbed competitor ametryn facilitated a physical phase transition of rigid paraffinic sorption domain to mobile and flexible domain during sorption process. We suggest that the different sorption-desorption behavior obtained for the two cuticles is related to the higher content of waxes (14% vs 2.6%) and lower content of cutin (46% vs 75%) in the A. americana versus tomato fruit cuticle.

  12. Ion-stimulated gas desorption yields and their dependence on the surface preparation of stainless steel

    CERN Document Server

    Mahner, E; Küchler, D; Malabaila, M; Taborelli, M

    2002-01-01

    Ion-induced gas desorption yields were investigated for 4.2 MeV/u lead ions incident on 316 LN stainless steel surfaces. Focussed on a possible application for the Low Energy Ion Ring (LEIR) vacuum system, the influence of surface treatments like chemical etching, electropolishing and gold-coating on the desorption yields was studied with accelerator-type vacuum chambers. The surface composition of similar prepared samples was investigated with X-ray Photoemission Spectroscopy (XPS). Desorption yields for H2, CH4, CO, Ar and CO2, which are of fundamental interest for LEIR and future accelerator applications, are reported as a function of impact angle, ion dose and charge state (+27, +53) of the lead ion beam.

  13. Effects of initial solute distribution on contaminant availability, desorption modeling, and subsurface remediation.

    Science.gov (United States)

    Haws, Nathan W; Ball, William P; Bouwer, Edward J

    2007-01-01

    Low permeability regions in which solute movement is governed by diffusion reduce the availability of pollutants for remediation and can function as long-term sources of groundwater contamination. The inherent difficulty in understanding mass transfer from these regions of sequestered contamination is further complicated by unknown solute distributions within the low-permeability regions (sequestering regions). When models are calibrated to reproduce temporal histories of solute release from a sequestering region (desorption), the fitted parameter values are used to infer the physical or chemical characteristics of the media; however, the calibrated parameters also reflect the case-specific initial conditions (i.e., the solute distribution within the sequestering region domain at the onset of desorption). This phenomenon is demonstrated using model simulations of solute diffusion from hypothetical solids with characteristics similar to those of the well studied Borden, Ontario aquifer system. Solute release from the solids is simulated using a batch diffusion model under different initial solute distributions within the solids. The results of these model simulations are used to calibrate parameters of a multiple first-order rate desorption model (MRM) to illustrate how the fitted MRM parameters increase or decrease depending on the initial "aging" of the solids. Further numerical simulations are conducted for a one-dimensional flow system under steady-state and variable-rate hydraulic flushing. These simulations show that although aging reduces desorptive mass flux during early stages of flushing, aged sites have greater desorptive mass flux (greater solute availability) than "freshly" contaminated media during the later stages of remediation. Overall, the results demonstrate why the physicochemical meaning of observed desorption rates cannot be accurately deduced without first understanding the initial solute distribution within the media.

  14. Hydrogenation of CO-bearing species on grains: unexpected chemical desorption of CO

    Science.gov (United States)

    Minissale, M.; Moudens, A.; Baouche, S.; Chaabouni, H.; Dulieu, F.

    2016-05-01

    The amount of methanol in the gas phase and the CO depletion from the gas phase are still open problems in astrophysics. In this work, we investigate solid-state hydrogenation of CO-bearing species via H-exposure of carbon monoxide, formaldehyde, and methanol-thin films deposited on cold surfaces, paying attention to the possibility of a return to the gas phase. The products are probed via infrared spectroscopy (reflection absorption infrared spectroscopy), and two types of mass spectroscopy protocols: temperature-programmed desorption, and during-exposure desorption techniques. In the case of the [CO+H] reactive system, we have found that chemical desorption of CO is more efficient than H-addition reactions and HCO and H2CO formation; the studies of the [H2CO +H] reactive system show a strong competition between all surface processes, chemical desorption of H2CO, H-addition (CH3OH formation) and H-abstraction (CO formation); finally, [CH3OH + H] seems to be a non-reactive system and chemical desorption of methanol is not efficient. CO-bearing species present a see-saw mechanism between CO and H2CO balanced by the competition of H-addition and H2-abstraction that enhances the CO chemical desorption. The chemical network leading to methanol has to be reconsidered. The methanol formation on the surface of interstellar dust grain is still possible through CO+H reaction; nevertheless, its consumption of adsorbed H atoms should be higher than previously expected.

  15. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

    Science.gov (United States)

    Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

  16. Ambient desorption/ionization mass spectrometry using a liquid sampling-atmospheric glow discharge (LS-APGD) ionization source.

    Science.gov (United States)

    Marcus, R Kenneth; Burdette, Carolyn Q; Manard, Benjamin T; Zhang, Lynn X

    2013-10-01

    A novel approach to ambient desorption/ionization mass spectrometry (ADI-MS) is described, based on a recently developed liquid sampling-atmospheric pressure glow discharge (LS-APGD) ionization source. The device is essentially unmodified relative to its implementation in elemental mass spectrometry, where the operational space is characterized by low operation power (LS-APGD source is mounted onto the source interface of a Thermo Finnigan LCQ Advantage Max quadrupole ion trap mass spectrometer without modifications to the instrument faceplate or ion optics. Described here is the initial evaluation of the roles of source geometry and working parameters, including electrolytic solution composition and plasma current, on the response of caffeine residues, with preliminary limits of detection based on the relative standard deviation of the spectral background suggested to be on the 10-pg level. Demonstrative spectra are presented for green tea extracts and raw leaves, coffee beans, a dried (raw) tobacco leaf, an analgesic tablet, and paper currency. Versatility is further revealed through the determination of components in common cigarette smoke. In each case, the spectra are characterized by (M + H)(+) species of the expected constituents. The capacity for a single source to perform both in solution and particulate elemental analysis (as shown previously) and ADI of molecular species is unique in the realm of mass spectrometry.

  17. Affinity mesh screen materials for selective extraction and analysis of antibiotics using transmission mode desorption electrospray ionization mass spectrometry.

    Science.gov (United States)

    Yang, Samuel H; Wang, Evelyn H; Gurak, John A; Bhawal, Sumit; Deshmukh, Rajendrasing; Wijeratne, Aruna B; Edwards, Brian L; Foss, Frank W; Timmons, Richard B; Schug, Kevin A

    2013-06-25

    The extraction of active compounds from natural sources has shown to be an effective approach to drug discovery. However, the isolation and identification of natural products from complex extracts can be an arduous task. A novel approach to drug discovery is presented through the use of polymer screens functionalized with an l-lysine-d-alanine-d-alanine (Kaa) peptide to create new affinity capture mesh screen materials. The Kaa sequence is a well-characterized specific binding site for antibiotics that inhibit cell wall synthesis in Gram-positive bacteria. The detailed synthesis and characterization of these novel screen materials are presented in this work. Polypropylene mesh screens were first coated with a poly(acrylic acid) film by pulsed plasma polymerization. The synthesized Kaa peptide was then covalently attached to carboxylic acid groups through a condensation reaction. An analysis of captured compounds was performed in a rapid fashion with transmission-mode desorption electrospray ionization (TM-DESI) mass spectrometry. A proof of principle was demonstrated to show the ability of the novel affinity capture materials to select for a macrocyclic antibiotic, vancomycin, over a negative control compound, spectinomycin. With further development, this method may provide a rapid screening technique for new antibacterial compounds, for example, those extracted from natural product sources having a limited supply. Here, we show that the screen can capture vancomycin preferentially over spectinomycin in a spiked extract of tea leaves.

  18. Survival of HCl( v=2) in trapping-desorption from MgO(100)

    Science.gov (United States)

    Korolik, M.; Suchan, M. M.; Johnson, M. J.; Arnold, D. W.; Reisler, H.; Wittig, C.

    2000-08-01

    An HCl molecular beam incident on MgO(100) is photoexcited to v=2, J=1 by using a pulsed parametric oscillator. At a translational energy of 0.11 eV, incident HCl is adsorbed. Thermal desorption yields v=2 molecules whose rotational and translational degrees of freedom are equilibrated at the surface temperature. Surface residence times for v=2 might be as long as 1 μs. At 180 K, it is concluded that a large fraction of surface-bound v=2 molecules reenter the gas phase, while at 120 K, deactivation exceeds desorption by an order of magnitude. Deactivation probably takes place at steps.

  19. Kinetic Modification on Hydrogen Desorption of Lithium Hydride and Magnesium Amide System

    OpenAIRE

    Hiroki Miyaoka; Yongming Wang,; Satoshi Hino; Shigehito Isobe; Kazuhiko Tokoyoda; Takayuki Ichikawa; Yoshitsugu Kojima

    2015-01-01

    Various synthesis and rehydrogenation processes of lithium hydride (LiH) and magnesium amide (Mg(NH2)2) system with 8:3 molar ratio are investigated to understand the kinetic factors and effectively utilize the essential hydrogen desorption properties. For the hydrogen desorption with a solid-solid reaction, it is expected that the kinetic properties become worse by the sintering and phase separation. In fact, it is experimentally found that the low crystalline size and the close contact of L...

  20. Impact of activated carbon, biochar and compost on the desorption and mineralization of phenanthrene in soil

    DEFF Research Database (Denmark)

    Marchal, Geoffrey; Smith, Kilian E.C.; Rein, Arno

    2013-01-01

    ), biochar or compost. Total amounts of phenanthrene desorbed were similar between the different soils, but the amendment type had a large influence. Complete desorption was observed in the unamended and compost amended soils, but this reduced for biochar (41% desorbed) and AC (8% desorbed). Cumulative...... amounts mineralized were 28% for the unamended control, 19% for compost, 13% for biochar and 4% for AC. Therefore, the effects of the amendments in soil in reducing desorption were also reflected in the extents of mineralization. Modeling was used to analyze key processes, indicating that for the AC...

  1. Derivatization of small biomolecules for optimized matrix-assisted laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Tholey, Andreas; Wittmann, Christoph; Kang, Min-Jung; Bungert, Ditte; Hollemeyer, Klaus; Heinzle, Elmar

    2002-09-01

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is a powerful tool for the measurement of low molecular mass compounds of biological interest. The limitations for this method are the volatility of many analytes, possible interference with matrix signals or bad ionization or desorption behavior of the compounds. We investigated the application of well-known and straightforward one-pot derivatization procedures to circumvent these problems. The derivatizations tested allow the measurement and the labeling of alcohols, aldehydes and ketones, carboxylic acids, alpha-ketocarboxylic acids and amines.

  2. Desorption of organophosphorous pesticides from soil with wastewater and surfactant solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Soriano, M. C.; Mingorance, M. D.; Pena, A.

    2009-07-01

    Surfactants can be introduced in the environment by wastewater discharge, point-charge pollution or deliberate action, e. g. to remediate contaminated soil or groundwater. The irrigation of soil with wastewater containing surfactants may modify pesticide desorption from soil, thus affecting their affecting their environmental fate. Desorption from soil of the plain of Granada (South-eastern Spain) of two organophosphorous pesticides, diazinon and dimethoate, differing in solubility and hydrophobicity, has been evaluated in the presence of different surfactant aqueous solutions and municipal wastewater. (Author)

  3. Kinetics of tetracycline, oxytetracycline, and chlortetracycline adsorption and desorption on two acid soils

    DEFF Research Database (Denmark)

    Fernandez Calviño, David; Bermúdez-Couso, Alipio; Arias-Estévez, Manuel

    2015-01-01

    The purpose of this work was to quantify retention/release of tetracycline, oxytetracycline, and chlortetracycline on two soils, paying attention to sorption kinetics and to implications of the adsorption/desorption processes on transfer of these pollutants to the various environmental compartments...... > chlortetracycline > tetracycline in soil 2. In conclusion, the SFC technique has yielded new kinetic data regarding tetracycline, oxytetracycline, and chlortetracycline adsorption/desorption on soils, indicating that it can be used to shed further light on the retention and transport processes affecting antibiotics...

  4. Recent progress in application of carbon nanomaterials in laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Wang, Jing; Liu, Qian; Liang, Yong; Jiang, Guibin

    2016-04-01

    Carbon nanomaterials have attracted great interest over past decades owing to their unique physical properties, versatile functionalization chemistry, and biological compatibility. In this article, we review recent progress in application of carbon nanomaterials in laser desorption/ionization mass spectrometry (LDI MS). Various types of carbon nanomaterials, including fullerenes, carbon nanotubes, graphene, carbon nanodots, nanodiamond, nanofibers, nanohorns, and their derivative forms, are involved. The applications of these materials as new matrices or probes in matrix-assisted or surface-enhanced laser desorption/ionization mass spectrometry (MALDI or SELDI MS) are discussed. Finally, we summarize current challenges and give our perspectives on the future of applications of carbon nanomaterials in LDI MS.

  5. Dynamic Moisture Sorption and Desorption in Fumed Silica-filled Silicone Foam

    Energy Technology Data Exchange (ETDEWEB)

    Trautschold, Olivia Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-02

    Characterizing dynamic moisture sorption and desorption in fumed silica-filled silicone foam is necessary for determining material compatibilities and life predictions, particularly in sealed environments that may be exposed to a range of environmental conditions. Thermogravimetric analysis (TGA) and near infrared spectroscopy (NIR) were performed on S5470 fumed silica-filled silicone foam to determine the weight percent of moisture at saturation. Additionally, TGA was used to determine the time, temperature, and relative humidity levels required for sorption and desorption of physisorbed moisture in S5470.

  6. Effect of transition-metal additives on hydrogen desorption kinetics of MgH2

    Science.gov (United States)

    Roy, Anindya; Janotti, Anderson; Van de Walle, Chris G.

    2013-01-01

    Using first-principles calculations, we study the effect of transition-metal additives (Ti, Fe, Co, and Ni) on the rate of hydrogen desorption in MgH2. The presence of large concentrations of transition-metal impurities causes the Fermi level to shift according to the position of the transition-metal acceptor/donor levels in the band gap. This shift can lower the formation energy of native defects and increase their concentration. The resulting higher rates of hydrogen desorption enhance the prospect of MgH2 as a solid-state hydrogen-storage material.

  7. Characterization of aromaticity in analogues of titan's atmospheric aerosols with two-step laser desorption ionization mass spectrometry

    Science.gov (United States)

    Mahjoub, Ahmed; Schwell, Martin; Carrasco, Nathalie; Benilan, Yves; Cernogora, Guy; Szopa, Cyril; Gazeau, Marie-Claire

    2016-10-01

    The role of polycyclic aromatic hydrocarbons (PAH) and Nitrogen containing PAH (PANH) as intermediates of aerosol production in the atmosphere of Titan has been a subject of controversy for a long time. An analysis of the atmospheric emission band observed by the Visible and Infrared Mapping Spectrometer (VIMS) at 3.28 μm suggests the presence of neutral polycyclic aromatic species in the upper atmosphere of Titan. These molecules are seen as the counter part of negative and positive aromatics ions suspected by the Plasma Spectrometer onboard the Cassini spacecraft, but the low resolution of the instrument hinders any molecular speciation. In this work we investigate the specific aromatic content of Titan's atmospheric aerosols through laboratory simulations. We report here the selective detection of aromatic compounds in tholins, Titan's aerosol analogs, produced with a capacitively coupled plasma in a N2:CH4 95:5 gas mixture. For this purpose, Two-Step Laser Desorption Ionization Time-of-Flight Mass Spectrometry (L2DI-TOF-MS) technique is used to analyze the so produced analogs. This analytical technique is based on the ionization of molecules by Resonance Enhanced Multi-Photon Ionization (REMPI) using a λ=248 nm wavelength laser which is selective for aromatic species. This allows for the selective identification of compounds having at least one aromatic ring. Our experiments show that tholins contain a trace amount of small PAHs with one to three aromatic rings. Nitrogen containing PAHs (PANHs) are also detected as constituents of tholins. Molecules relevant to astrobiology are detected as is the case of the substituted DNA base adenine.

  8. plasma treatment

    Directory of Open Access Journals (Sweden)

    Puač Nevena

    2014-11-01

    Full Text Available In this paper we will present results for plasma sterilization of planktonic samples of two reference strains of bacteria, Pseudomonas aeruginosa ATCC 27853 and Enterococcus faecalis ATCC 29212. We have used a plasma needle as a source of non-equilibrium atmospheric plasma in all treatments. This device is already well characterized by OES, derivative probes and mass spectrometry. It was shown that power delivered to the plasma is bellow 2 W and that it produces the main radical oxygen and nitrogen species believed to be responsible for the sterilization process. Here we will only present results obtained by electron paramagnetic resonance which was used to detect the OH, H and NO species. Treatment time and power delivered to the plasma were found to have the strongest influence on sterilization. In all cases we have observed a reduction of several orders of magnitude in the concentration of bacteria and for the longest treatment time complete eradication. A more efficient sterilization was achieved in the case of gram negative bacteria.

  9. Plasma metallization

    CERN Document Server

    Crowther, J M

    1997-01-01

    Many methods are currently used for the production of thin metal films. However, all of these have drawbacks associated with them, for example the need for UHV conditions, high temperatures, exotic metal precursors, or the inability to coat complex shaped objects. Reduction of supported metal salts by non-isothermal plasma treatment does not suffer from these drawbacks. In order to produce and analyse metal films before they become contaminated, a plasma chamber which could be attached directly to a UHV chamber with XPS capability was designed and built. This allowed plasma treatment of supported metal salts and surface analysis by XPS to be performed without exposure of the metal film to the atmosphere. Non-equilibrium plasma treatment of Nylon 66 supported gold(lll) chloride using hydrogen as the feed gas resulted in a 95% pure gold film, the remaining 5% of the film being carbon. If argon or helium were used as the feed gases during plasma treatment the resultant gold films were 100% pure. Some degree of s...

  10. Plasma dynamo

    CERN Document Server

    Rincon, F; Schekochihin, A A; Valentini, F

    2015-01-01

    Magnetic fields pervade the entire Universe and, through their dynamical interactions with matter, affect the formation and evolution of astrophysical systems from cosmological to planetary scales. How primordial cosmological seed fields arose and were further amplified to $\\mu$Gauss levels reported in nearby galaxy clusters, near equipartition with kinetic energy of plasma motions and on scales of at least tens of kiloparsecs, is a major theoretical puzzle still largely unconstrained by observations. Extragalactic plasmas are weakly collisional (as opposed to collisional magnetohydrodynamic fluids), and whether magnetic-field growth and its sustainment through an efficient dynamo instability driven by chaotic motions is possible in such plasmas is not known. Fully kinetic numerical simulations of the Vlasov equation in a six-dimensional phase space necessary to answer this question have until recently remained beyond computational capabilities. Here, we show by means of such simulations that magnetic-field a...

  11. Optical laser-induced CO desorption from Ru(0001) monitored with a free-electron X-ray laser

    DEFF Research Database (Denmark)

    Öberg, H.; Gladh, J.; Dell'Angela, M.

    2015-01-01

    We present density functional theory modeling of time-resolved optical pump/X-ray spectroscopic probe data of CO desorption from Ru(0001). The BEEF van der Waals functional predicts a weakly bound state as a precursor to desorption. The optical pump leads to a near-instantaneous (b100 fs) increas...

  12. A New Method for Determination of Adsorption and Desorption Coefficients of Pesticides with Soil Column Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The adsorption and desorption coefficients of atrazine, methiocarb and simazine on a sandy loam soil were measured in this study with soil column liquid chromatographic (SCLC) technique. The adsorption and desorption data of all the three pesticides followed Freundlich isotherms revealing the existence of hysteresis. In comparing with other methods, SCLC method showed some characteristics such as rapidity, online and accuracy.

  13. Sorption-desorption of fipronil in some soils, as influenced by ionic strength, pH and temperature.

    Science.gov (United States)

    Singh, Anand; Srivastava, Anjana; Srivastava, Prakash C

    2016-08-01

    The sorption-desorpion of fipronil insecticide is influenced by soil properties and variables such as pH, ionic strength, temperature, etc. A better understanding of soil properties and these variables in sorption-desorption processes by quantification of fipronil using liquid chromatography may help to optimise suitable soil management to reduce contamination of surface and groundwaters. In the present investigation, the sorption-desorption of fipronil was studied in some soils at varying concentrations, ionic strengths, temperatures and pH values, and IR specta of fipronil sorbed onto soils were studied. The sorption of fipronil onto soils conformed to the Freundlich isotherm model. The sorption-desorption of fipronil varied with ionic strength in each of the soils. Sorption decreased but desorption increased with temperature. Sorption did not change with increasing pH, but for desorption there was no correlation. The cumulative desorption of fipronil from soil was significantly and inversely related to soil organic carbon content. IR spectra of sorbed fipronil showed the involvement of amino, nitrile, sulfone, chloro and fluoro groups and the pyrazole nucleus of the fipronil molecule. The sorption of fipronil onto soils appeared to be a physical process with the involvement of hydrogen bonding. An increase in soil organic carbon may help to reduce desorption of fipronil. High-temperature regimes are more conducive to the desorption. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  14. Retention of Nickel in Soils: Sorption-Desorption and Extended X-ray Absorption Fine Structure Experiments

    Science.gov (United States)

    Adsorption and desorption of heavy metals in soils are primary factors that influence their bioavailability and mobility in the soil profile. To examine the characteristics of nickel (Ni) adsorption-desorption in soils, kinetic batch experiments were carried out followed by Ni re...

  15. Plasma medicine

    CERN Document Server

    Fridman, Alexander

    2012-01-01

    This comprehensive text is suitable for researchers and graduate students of a 'hot' new topic in medical physics. Written by the world's leading experts,  this book aims to present recent developments in plasma medicine, both technological and scientific, reviewed in a fashion accessible to the highly interdisciplinary audience consisting of doctors, physicists, biologists, chemists and other scientists, university students and professors, engineers and medical practitioners. The book focuses on major topics and covers the physics required to develop novel plasma discharges relevant for medic

  16. Heavy-ion induced desorption yields of cryogenic surfaces bombarded with 4.2 MeV/u lead ions

    CERN Document Server

    Mahner, E; Evans, L; Kollmus, H; Küchler, D; Scrivens, R; Severin, D; Wengenroth, M; CERN. Geneva. ATS Department

    2011-01-01

    The ion-induced desorption experiment, installed in the CERN Heavy-Ion Accelerator LINAC 3, has been used to study the dynamic outgassing of cryogenic surfaces. Two different targets, bare and goldcoated copper, were bombarded under perpendicular impact with 4.2 MeV/u Pb54+ ions. Partial pressure rises of H2, CH4, CO, and CO2 and effective desorption yields were measured at 300, 77, and 6.3 K using single shot and continuous ion bombardment techniques. We find that the heavy-ion-induced desorption yield is temperature dependent and investigate the influence of CO gas cryosorbed at 6.3 K. The gain in desorption yield reduction at cryogenic temperature vanishes after several monolayers of CO are cryosorbed on both targets. In this paper we describe the new cryogenic target assembly, the temperature-dependent pressure rise, desorption yield, and gas adsorption measurements.

  17. Desorption of deuterium from beryllium codeposits using flash heating

    Science.gov (United States)

    Yu, J. H.; Baldwin, M. J.; Doerner, R. P.; Pitts, R. A.; Smirnov, R. D.; Xu, H. W.

    2013-07-01

    As a result of safety concerns, limits will be placed on the allowable tritium inventory retained inside the ITER vacuum vessel. The primary motivation for the present work is to test the proposed method of removing tritium from main chamber codeposits using radiative heat flashing from controlled ITER plasma shutdowns. Detritiation of Be codeposits is studied in the PISCES-B facility using flash-heating by a 10 ms laser with up to 2 MJ/m2 of absorbed energy density. Three types of codeposits are flash-heated with layer thickness ranging from 0.1 to 1.2 μm. Less than 25% of the D in the Be layer escapes at ITER-relevant flash energy densities and with peak surface temperature up to ˜900 °C. Repetitive flashing with peak surface temperature of 400-500 °C results in an increased population of higher energy trap sites, implying that transient heating which causes appropriate surface temperature excursion redistributes D among codeposit trap sites.

  18. Enhanced conductivity of aluminum doped ZnO films by hydrogen plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chang, H.P. [Department of Electrical Engineering and Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Wang, F.H., E-mail: fansen@dragon.nchu.edu.t [Department of Electrical Engineering and Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Wu, J.Y.; Kung, C.Y.; Liu, H.W. [Department of Electrical Engineering and Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 402, Taiwan (China)

    2010-10-01

    Aluminum doped zinc oxide (AZO) thin films prepared by radio-frequency (RF) magnetron sputtering at various RF power were treated by hydrogen plasma to enhance the characteristics for transparent electrode applications. The hydrogen plasma treatment was carried out at 300 {sup o}C in a plasma enhanced chemical vapor deposition system. X-ray diffraction analysis shows that all AZO films have a (002) preferred orientation and film crystallinity seems no significant change after plasma treatment. The plasma treatment not only significantly decreases film resistivity but enhances electrical stability as aging in air ambient. The improved electrical properties are due to desorption of weakly bonded oxygen species, formation of Zn-H type species and passivation of deep-level defects during plasma treatment.

  19. Enhanced desorption of phenanthrene from contaminated soil using anionic/nonionic mixed surfactant.

    Science.gov (United States)

    Zhou, Wenjun; Zhu, Lizhong

    2007-05-01

    A new approach using an anionic/nonionic mixed surfactant, sodium dodecyl sulphate (SDS) with Triton X-100 (TX100), was utilized for the desorption of phenanthrene from an artificial contaminated natural soil in an aim to improve the efficiency of surfactant remediation technology. The experimental results showed that the presence of SDS not only reduced the sorption of TX100 onto the natural soil, but also enhanced the solubilization of TX100 for phenanthrene, both of which resulted in the distribution of phenanthrene in soil-water systems decreasing with increasing mole fraction of SDS in surfactant solutions. These results can be attributed to the formation of mixed micelles in surfactant solution and the corresponding decrease in the critical micelle concentration of TX100 in mixed solution. The batch desorption experiments showed that the desorption percentage of phenanthrene from the contaminated soil with mixed solution was greater than that with single TX100 solution and appeared to be positively related to the mole fraction of SDS in surfactant solution. Thus, the anionic/nonionic mixed surfactants are more effective for the desorption of phenanthrene from the contaminated soil than a single nonionic surfactant.

  20. Desorption of cryogenic layers of the solid hydrogens by electron bombardment

    DEFF Research Database (Denmark)

    Schou, Jørgen; Tratnik, Herbert; Thestrup Nielsen, Birgitte

    2008-01-01

    For solid hydrogenic films in the thickness range from similar to 50 ML to similar to 500 ML the desorption yield falls off inversely proportional to the thickness for both H-2 and D-2 films. This behavior is common for data obtained at CERN for solid H-2 and at Riso National Laboratory for solid...

  1. Molecular-scale Description of SPAN80 Desorption from the Squalane-Water Interface

    CERN Document Server

    Tan, L; Chaudhari, M I

    2016-01-01

    Extensive all-atom molecular dynamics calculations on the water-squalane interface for nine different loadings with sorbitan monooleate (SPAN80), at $T=300$K, are analyzed for the surface tension equation of state, desorption free energy profiles as they depend on loading, and to evaluate escape times for absorbed SPAN80 into the bulk phases. These results suggest that loading only weakly affects accommodation of a SPAN80 molecule by this squalane-water interface. Specifically, the surface tension equation of state is simple through the range of high tension to high loading studied, and the desorption free energy profiles are weakly dependent on loading here. The perpendicular motion of the centroid of the SPAN80 head-group ring is well-described by a diffusional model near the minimum of the desorption free energy profile. Lateral diffusional motion is weakly dependent on loading. Escape times evaluated on the basis of a diffusional model and the desorption free energies are $7\\times 10^{-2}$ s (into the squ...

  2. Glyphosate sorption/desorption on biochars – Interactions of physical and chemical processes

    Science.gov (United States)

    BACKGROUND: Biochar, a carbon-rich product of biomass pyrolysis, could limit glyphosate transport in soil and remediate contaminated water. The present study investigates the sorption/desorption behavior of glyphosate on biochars prepared from different hardwoods at temperatures ranging from 350°C t...

  3. Helium Retention and Desorption Behaviour of Reduced Activation Ferritic/Martenstic Steel

    Science.gov (United States)

    Wang, Pinghuai; Nobuta, Yuji; Hino, Tomoaki; Yamauchi, Yuji; Chen, Jiming; Xu, Zengyu; Li, Xiongwei; Liu, Shi

    2009-04-01

    The reduced activation ferritic/martenstic steel CLF-1 prepared by the Southwestern Institute of Physics in China was irradiated by helium ions with an energy of 5 keV at room temperature using an electron cyclotron resonance (ECR) ion irradiation apparatus. After the irradiation, the helium retention and desorption were investigated using a technique of thermal desorption spectroscopy (TDS). The experiment was conducted with both the normal and welded samples. Blisters were observed after the helium ion irradiation, and the surface density of blisters in the welded samples was lower than that in the non-welded samples. Three desorption peaks were observed in both the non-welded and welded samples. These desorption peaks corresponded to those of blister ruptures and the helium release from the inner bubbles and the defects. The amount of helium retained in the welded samples was approximately the same as that in the non-welded samples, which was much less than other reduced activation materials, such as vanadium alloy and SiC/SiC composites.

  4. Role of nano in catalysis: Pd catalyzed H desorption from MgH2

    Science.gov (United States)

    Xie, Weiyu; West, Damien; Sun, Yiyang; Zhang, Shengbai

    2012-02-01

    Magnesium hydride (MgH2) is promising for on-board hydrogen (H) storage with the major hurdle being the slow desorption kinetics. H desorption from ball-milled MgH2 peaks at two slightly different temperatures, which further split in the presence of palladium catalyst. It has been experimentally demonstrated that nanostructuring can eliminate the high temperature peak. However, the effect of nanostructuring cannot be explained by thermodynamic destabilization due to quantum size effect. Our first-principles calculation reveals that there exist two reaction pathways for H desorption from MgH2. One involves H vacancy (SV) diffusion at surface, while the other one involves H atom diffusion in bulk. The SV pathway self-terminates as dehydrogenation eventually eliminates the exposed MgH2 region. Therefore, it is size-sensitive and fully functions only when the surface-to-bulk ratio is large, which is available only in nanostructures. Our calculation further shows that the SV pathway significantly lowers the desorption barrier, because it decouples the H transport process with the surface liftoff process and benefits from a fact that diffusion of vacancies at surface can have significantly lower barrier than that in bulk.

  5. Desorption of arsenic from exhaust activated carbons used for water purification.

    Science.gov (United States)

    Di Natale, F; Erto, A; Lancia, A

    2013-09-15

    This work aims to the analysis of arsenic desorption from an exhaust activated carbon used for the purification of a natural water. This last was used to mimic the properties of common groundwater or drinking water. Different low-cost and harmless eluting solutions were considered, including distilled water, natural water, saline (NaCl, CaCl₂ and NaNO₃) and basic (NaOH) solutions. Experimental results showed that, for 1g of activated carbon with arsenic loading close to the maximum value available for the model natural water (ω ≈ 0.1 mg/g), it is possible to recover more than 80% of the arsenic using 20 ml of 0.1 M sodium chloride solution. A temperature variation within 20 and 40 °C has scarce effect on desorption efficiency. A comparison between desorption data and adsorption isotherms data suggests that arsenic adsorption is actually a reversible process. Therefore, it is virtually possible to increase arsenic recovery efficiency close to 100% by increasing the NaCl concentration or the volume of the desorption solution, but a preliminary cost benefit analysis lead to consider a NaCl 0.1M solution as an optimal solution for practical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. New insight into the electrochemical desorption of alkanethiol SAMs on gold.

    Science.gov (United States)

    Pensa, Evangelina; Vericat, Carolina; Grumelli, Doris; Salvarezza, Roberto C; Park, Sung Hyun; Longo, Gabriel S; Szleifer, Igal; Méndez De Leo, Lucila P

    2012-09-21

    A combination of Polarization Modulation Infrared Reflection Absorption Spectroscopy (PMIRRAS) under electrochemical control, Electrochemical Scanning Tunneling Microscopy (ECSTM) and Molecular Dynamics (MD) simulations has been used to shed light on the reductive desorption process of dodecanethiol (C12) and octadecanethiol (C18) SAMs on gold in aqueous electrolytes. Experimental PMIRRAS, ECSTM and MD simulations data for C12 desorption are consistent with formation of randomly distributed micellar aggregates stabilized by Na(+) ions, coexisting with a lying-down phase of molecules. The analysis of pit and Au island coverage before and after desorption is consistent with the thiolate-Au adatoms models. On the other hand, PMIRRAS and MD data for C18 indicate that the desorbed alkanethiolates adopt a Na(+) ion-stabilized bilayer of interdigitated alkanethiolates, with no evidence of lying down molecules. MD simulations also show that both the degree of order and tilt angle of the desorbed alkanethiolates change with the surface charge on the metal, going from bilayers to micelles. These results demonstrate the complexity of the alkanethiol desorption in the presence of water and the fact that chain length and counterions play a key role in a complex structure.

  7. Desorption isotherms, drying characteristics and qualities of glace tropical fruits undergoing forced convection solar drying

    Energy Technology Data Exchange (ETDEWEB)

    Jamradloedluk, Jindaporn; Wiriyaumpaiwong, Songchai [Mahasarakham Univ. Khamriang, Kantarawichai, Mahasarakham (Thailand)

    2008-07-01

    Solar energy, a form of sustainable energy, has a great potential for a wide variety of applications because it is abundant and accessible, especially for countries located in the tropical region. Drying process is one of the prominent techniques for utilization of solar energy. This research work proposes a forced convection solar drying of osmotically pretreated fruits viz. mango, guava, and pineapple. The fruit cubes with a dimension of 1cm x 1cm x 1cm were immersed in 35% w./w. sucrose solution prior to the drying process. Drying kinetics, color and hardness of the final products obtained from solar drying were investigated and compared with those obtained from open air-sun drying. Desorption isotherms of the osmosed fruits were also examined and five mathematical models were used to fit the desorption curves. Experimental results revealed that solar drying provided higher drying rate than natural sun drying. Color of glace fruit processed by solar drying was more intense, indicated by lower value of lightness and higher value of yellowness, than that processed by sun drying. Hardness of the products dehydrated by both drying methods, however, was not significantly different (p>0.05). Validation of the mathematical models developed showed that the GAB model was most effective for describing desorption isotherms of osmotically pretreated mango and pineapple whereas Peleg's model was most effective for describing desorption isotherms of osmotically pretreated guava. (orig.)

  8. Charging-assisted desorption of deuterium films by keV electrons

    DEFF Research Database (Denmark)

    Schou, Jørgen; Thestrup Nielsen, Birgitte; Pedersen, Thomas Garm

    2009-01-01

    m. The initial film thickness and the mass loss as result of desorption were monitored by the QCM. The electron beam current was kept at about or below 100 nA to avoid beam-induced evaporation. Secondary electron emission was suppressed to a value below 0.01-0.03 electrons/electron by a repeller...

  9. ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS - THE THERMAL DESORPTION UNIT - APPLICATIONS ANALYSIS REPORT

    Science.gov (United States)

    ELI ECO Logic International, Inc.'s Thermal Desorption Unit (TDU) is specifically designed for use with Eco Logic's Gas Phase Chemical Reduction Process. The technology uses an externally heated bath of molten tin in a hydrogen atmosphere to desorb hazardous organic compounds fro...

  10. The desorption of ammonia and carbon dioxide from multicomponent solutions: I. Model description and development

    Directory of Open Access Journals (Sweden)

    Jotanović Milovan B.

    2002-01-01

    Full Text Available A mathematical model of the desorption process based on the synthesised technological topology of the regeneration process gas components NH3 and CO2, was developed. The logical principle methodology of the mathematical modelling of desorption processes was worked out in detail. The mathematical model of the process, including the following: - The synthesized technological scheme of the desorption of components NH3 and CO2, with all the necessary requirements and limitations of the mathematical model; - The relevant multicomponent systems which exist in the process were defined in which the interphase transformation occurs; - The considered units (aparatus are defined which make up the basic technological topology of the process; - Desorption processes in towers with different types of trays were defined and mathematically described; - The cooling process and condensation of gas phase in a complex multicomponent system was of the gas phase in a complex multicomponent system was defined and mathematically described. Many variants of the process were analyzed by using developed model with the aim of determining the relevant functional dependences between some basic parameters of the process. They will be published in the second part of this study.

  11. Time-Dependent Zinc Desorption in Some Calcareous Soils of Iran

    Institute of Scientific and Technical Information of China (English)

    M.BARANIMOTLAGH; M.GHOLAMI

    2013-01-01

    Desorption of zinc (Zn) from soil is an important factor governing Zn concentration in the soil solution and Zn availability to plants.Batch experiments were performed to study the kinetics of Zn desorption by diethylenetriaminepentaacetic acid (DTPA) from 15 calcareous soil samples taken from Golestan Province in northern Iran.Soils were equilibrated with 0.005 mol L-1 DTPA solutions for 0.25 to 192 h.The results showed that the extraction process consisted of rapid extraction in the first 2 h followed by much slower extraction for the remainder of the experiment.Desorption kinetic data was fitted to pseudo-first-order kinetic model.The experimental data were found to deviate from the straight line of the pseudo-first-order plots after 2 h.The model of two first-order reactions was fitted to the kinetic data and allowed to distinguish two pools for Zn:a labile fraction (Q1),quickly extracted with a rate constant k1,and a slowly labile fraction (Q2),more slowly extracted with a rate constant k2.The applicability of pseudo-second-order model in describing the kinetic data of Zn desorption was also evaluated.

  12. Offline thermal-desorption proton-transfer-reaction mass spectrometry to study composition of organic aerosol

    NARCIS (Netherlands)

    Timkovsky, J.; Dusek, U.; Henzing, J. S.; Kuipers, T. L.; Röckmann, T.; Holzinger, R.

    2015-01-01

    We present a novel approach to study the organic composition of aerosol filter samples using thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) in the laboratory. The method is tested and validated based on the comparison with in situ TD-PTR-MS measurements. In general, we obs

  13. Mechanical Behavior of Methane Infiltrated Coal: the Roles of Gas Desorption, Stress Level and Loading Rate

    Science.gov (United States)

    Wang, Shugang; Elsworth, Derek; Liu, Jishan

    2013-09-01

    We report laboratory experiments to investigate the role of gas desorption, stress level and loading rate on the mechanical behavior of methane infiltrated coal. Two suites of experiments are carried out. The first suite of experiments is conducted on coal (Lower Kittanning seam, West Virginia) at a confining stress of 2 MPa and methane pore pressures in the fracture of 1 MPa to examine the role of gas desorption. These include three undrained (hydraulically closed) experiments with different pore pressure distributions in the coal, namely, overpressured, normally pressured and underpressured, and one specimen under drained condition. Based on the experimental results, we find quantitative evidence that gas desorption weakens coal through two mechanisms: (1) reducing effective stress controlled by the ratio of gas desorption rate over the drainage rate, and (2) crushing coal due to the internal gas energy release controlled by gas composition, pressure and content. The second suite of experiments is conducted on coal (Upper B seam, Colorado) at confining stresses of 2 and 4 MPa, with pore pressures of 1 and 3 MPa, under underpressured and drained condition with three different loading rates to study the role of stress level and loading rate. We find that the Biot coefficient of coal specimens is coal. This study has important implications for the stability of underground coal seams.

  14. Role of organic matter on boron adsorption-desorption hysteresis of soils

    Science.gov (United States)

    In this study we evaluated the boron (B) adsorption/desorption reaction in six soils and examined the extent to which organic matter content, as well as incubation time affected B release. Six soils varying in initial pH, clay content, and were selected for the study. Adsorption experiments were c...

  15. Silver impregnated carbon for adsorption and desorption of elemental mercury vapors

    Institute of Scientific and Technical Information of China (English)

    Despina Karatza; Marina Prisciandaro; Amedeo Lancia; Dino Musmarra

    2011-01-01

    The Hg0 vapor adsorption experimental results on a novel sorbent obtained by impregnating a commercially available activated carbon (Darco G60 from BDH) with silver nitrate were reported.The study was performed by using a fundamental approach,in an apparatus at laboratory scale in which a synthetic flue gas,formed by Hg0 vapors in a nitrogen gas stream,at a given temperature and mercury concentration,was flowed through a fixed bed of adsorbent material.Breakthrough curves and adsorption isotherms were obtained for bed temperatures of 90,120 and 150°C and for Hg0 concentrations in the gas varying in the range of 0.8-5.0 mg/m3.The experimental gas-solid equilibrium data were used to evaluate the Langmuir parameters and the heat of adsorption.The experimental results showed that silver impregnated carbon was very effective to capture elemental mercury and the amount of mercury adsorbed by the carbon decreased as the bed temperature increased.In addition,to evaluate the possibility of adsorbent recovery,desorption was also studied.Desorption runs showed that both the adsorbing material and the mercury could be easily recovered,since at the end of desorption the residue on solid was almost negligible.The material balance on mercury and the constitutive equations of the adsorption phenomenon were integrated,leading to the evaluation of only one kinetic parameter which fits well both the experimentally determined breakthrough and desorption curves.

  16. Silver impregnated carbon for adsorption and desorption of elemental mercury vapors.

    Science.gov (United States)

    Karatza, Despina; Prisciandaro, Marina; Lancia, Amedeo; Musmarra, Dino

    2011-01-01

    The Hg(0) vapor adsorption experimental results on a novel sorbent obtained by impregnating a commercially available activated carbon (Darco G60 from BDH) with silver nitrate were reported. The study was performed by using a fundamental approach, in an apparatus at laboratory scale in which a synthetic flue gas, formed by Hg(0) vapors in a nitrogen gas stream, at a given temperature and mercury concentration, was flowed through a fixed bed of adsorbent material. Breakthrough curves and adsorption isotherms were obtained for bed temperatures of 90, 120 and 150 degrees C and for Hg(0) concentrations in the gas varying in the range of 0.8-5.0 mg/m3. The experimental gas-solid equilibrium data were used to evaluate the Langmuir parameters and the heat of adsorption. The experimental results showed that silver impregnated carbon was very effective to capture elemental mercury and the amount of mercury adsorbed by the carbon decreased as the bed temperature increased. In addition, to evaluate the possibility of adsorbent recovery, desorption was also studied. Desorption runs showed that both the adsorbing material and the mercury could be easily recovered, since at the end of desorption the residue on solid was almost negligible. The material balance on mercury and the constitutive equations of the adsorption phenomenon were integrated, leading to the evaluation of only one kinetic parameter which fits well both the experimentally determined breakthrough and desorption curves.

  17. Direct measurement of desorption and diffusion energies of O and N atoms physisorbed on amorphous surfaces

    CERN Document Server

    Minissale, Marco; Dulieu, François

    2016-01-01

    Physisorbed atoms on the surface of interstellar dust grains play a central role in solid state astrochemistry. Their surface reactivity is one source of the observed molecular complexity in space. In experimental astrophysics, the high reactivity of atoms also constitutes an obstacle to measuring two of the fundamental properties in surface physics, namely desorption and diffusion energies, and so far direct measurements are non-existent for O and N atoms. We investigated the diffusion and desorption processes of O and N atoms on cold surfaces in order to give boundary conditions to astrochemical models. Here we propose a new technique for directly measuring the N- and O-atom mass signals. Including the experimental results in a simple model allows us to almost directly derive the desorption and diffusion barriers of N atoms on amorphous solid water ice (ASW) and O atoms on ASW and oxidized graphite. We find a strong constraint on the values of desorption and thermal diffusion energy barriers. The measured b...

  18. Role of desorption kinetics in the rhamnolipid-enhanced biodegradation of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Congiu, Eleonora; Ortega-Calvo, José-Julio

    2014-09-16

    The main aim of this study was to investigate the effect of a rhamnolipid biosurfactant on biodegradation of (14)C-labeled phenanthrene and pyrene under desorption-limiting conditions. The rhamnolipid caused a significant solubilization and enhanced biodegradation of PAHs sorbed to soils. The enhancement was, however, negatively influenced by experimental conditions that caused an enrichment of slow desorption fractions. These conditions included aging, a higher organic matter content in soil, and previous extraction with Tenax to remove the labile-desorbing chemical. The decline in bioavailability caused by aging on sorbed (14)C-pyrene was partially reversed by rhamnolipids, which enhanced mineralization of the aged compound, although not so efficiently like with the unaged chemical. This loss in biosurfactant efficiency in promoting biodegradation can be explained by intra-aggregate diffusion of the pollutant during aging. We suggest that rhamnolipid can enhance biodegradation of soil-sorbed PAHs by micellar solubilization, which increase the cell exposure to the chemicals in the aqueous phase, and partitioning into soil organic matter, thus enhancing the kinetics of slow desorption. Our study show that rhamnolipid can constitute a valid alternative to chemical surfactants in promoting the biodegradation of slow desorption PAHs, which constitutes a major bottleneck in bioremediation.

  19. Absorption and desorption mass transfer rates in non-reactive systems

    NARCIS (Netherlands)

    Hamborg, Espen S.; Kersten, Sascha R. A.; Versteeg, Geert F.

    2010-01-01

    Liquid phase mass transfer coefficients have been measured in a controlled environment during gas absorption into a liquid and gas desorption from a liquid in a batch operated stirred tank reactor over a wide range of operating conditions. At identical operating conditions, the mass transfer

  20. Characterisation of bacteria by matrix-assisted laser desorption/ionisation and electrospray mass spectrometry

    NARCIS (Netherlands)

    Baar, B.L.M. van

    2000-01-01

    Chemical analysis for the characterisation of micro-organisms is rapidly evolving, after the recent advent of new ionisation methods in mass spectrometry (MS): electrospray (ES) and matrix-assisted laser desorption/ionisation (MALDI). These methods allow quick characterisation of micro-organisms, ei

  1. Effect of biochar amendment on tylosin adsorption-desorption and transport in two different soils

    Science.gov (United States)

    Chang Yoon Jeong; Jim J. Wang; Syam K. Dodla; Thomas L. Eberhardt; Les Groom

    2012-01-01

    The role of biochar as a soil amendment on the adsorption¨C desorption and transport of tylosin, a macrolide class of veterinary antibiotic, is little known. In this study, batch and column experiments were conducted to investigate the adsorption kinetics and transport of tylosin in forest and agricultural corn field soils amended with hardwood and softwood biochars....

  2. Electric field induced desorption of bacteria from a conditioning film covered substratum.

    Science.gov (United States)

    Poortinga, A T; Smit, J; van der Mei, H C; Busscher, H J

    2001-12-01

    Desorption of three oral bacterial strains from a salivary conditioning film on an indium tin oxide electrode during application of a positive (bacterial adhesion to the anode) or a negative electric current was studied in a parallel plate flow chamber. Bacterial adhesion was from a flowing suspension of high ionic strength, after which the bacterial suspension was replaced by a low ionic strength solution without bacteria and currents ranging from -800 to +800 microA were applied. Streptococcus oralis J22 desorbed during application of a positive and negative electric current with a desorption probability that increased with increasing electric current. Two actinomyces strains, however, could not be stimulated to desorb by the electric currents applied. The desorption forces acting on adhering bacteria are electroosmotic in origin and working parallel to the electrode surface in case of a positive current, whereas they are electrophoretic and electrostatic in origin and working perpendicular to the surface in case of a negative current. By comparison of the effect of positive and negative electric currents, it can be concluded that parallel forces are more effective in stimulating bacterial desorption than perpendicular forces. The results of this study point to a new pathway of cleaning industrial and biomedical surfaces without the use of detergents or biocides.

  3. Desorption electrospray ionization mass spectrometry in the analysis of chemical food contaminants in food

    NARCIS (Netherlands)

    Nielen, M.W.F.; Hooijerink, H.; Zomer, P.; Mol, J.G.J.

    2011-01-01

    Since its introduction, desorption electrospray ionization (DESI) mass spectrometry (MS) has been mainly applied in pharmaceutical and forensic analysis. We expect that DESI will find its way in many different fields, including food analysis. In this review, we summarize DESI developments aimed at

  4. Laser Infrared Desorption Spectroscopy to Detect Complex Organic Molecules on Icy Planetary Surfaces

    Science.gov (United States)

    Sollit, Luke S.; Beegle, Luther W.

    2008-01-01

    Laser Desorption-Infrared Spectroscopy (LD-IR) uses an IR laser pulse to desorb surface materials while a spectrometer measures the emission spectrum of the desorbed materials (Figure 1). In this example, laser desorption operates by having the incident laser energy absorbed by near surface material (10 microns in depth). This desorption produces a plume that exists in an excited state at elevated temperatures. A natural analog for this phenomenon can be observed when comets approach the sun and become active and individual molecular emission spectra can be observed in the IR [1,2,3,4,5]. When this occurs in comets, the same species that initially emit radiation down to the ground state are free to absorb it, reducing the amount of detectable emission features. The nature of our technique results in absorption not occurring, because the laser pulse could easily be moved away form the initial desorption plume, and still have better spatial resolution then reflectance spectroscopy. In reflectance spectroscopy, trace components have a relatively weak signal when compared to the entire active nature of the surface. With LDIR, the emission spectrum is used to identify and analyze surface materials.

  5. Desorption of acetone from alkaline-earth exchanged Y zeolite after propane selective oxidation

    NARCIS (Netherlands)

    Xu, Jiang; Mojet, B.L.; Ommen, van J.G.; Lefferts, L.

    2004-01-01

    The desorption of products from a series of alkaline-earth exchanged Y zeolites after room-temperature propane selective oxidation was investigated by in situ infrared and mass spectroscopy. The intermediate product, isopropylhydroperoxide (IHP), did not desorb during temperature-programmed-desorpti

  6. Impact of activated carbon, biochar and compost on the desorption and mineralization of phenanthrene in soil

    DEFF Research Database (Denmark)

    Marchal, Geoffrey; Smith, Kilian E.C.; Rein, Arno

    2013-01-01

    Sorption of PAHs to carbonaceous soil amendments reduces their dissolved concentrations, limiting toxicity but also potentially biodegradation. Therefore, the maximum abiotic desorption of freshly sorbed phenanthrene (≤5 mg kg−1) was measured in three soils amended with activated carbon (AC...

  7. Helium Retention and Desorption Behaviour of Reduced Activation Ferritic/Martenstic Steel

    Institute of Scientific and Technical Information of China (English)

    WANG Pinghuai; NOBUTA Yuji; HINO Tomoaki; YAMAUCHI Yuji; CHEN Zilning; XU Zengyu; LI Xiongwei; LIU Shi

    2009-01-01

    The reduced activation ferritic/martenstic steel CLF-1 prepared by the Southwest-ern Institute of Physics in China was irradiated by helium ions with an energy of 5 keV at room temperature using an electron cyclotron resonance (ECR) ion irradiation apparatus. After the irradiation, the helium retention and desorption were investigated using a technique of thermal desorption spectroscopy (TDS). The experiment was conducted with both the normal and welded samples. Blisters were observed after the helium ion irradiation, and the surface density of blisters in the welded samples was lower than that in the non-welded samples. Three desorption peaks were observed in both the non-welded and welded samples. These desorption peaks corresponded to those of blister ruptures and the helium release from the inner bubbles and the defects. The amount of helium retained in the welded samples was approximately the same as that in the non-welded samples, which was much less than other reduced activation materials, such as vanadium alloy and SiC/SiC composites.

  8. Adsorption and desorption of phosphate on limestone in experiments simulating seawater intrusion

    Science.gov (United States)

    The absorption and desorption of phosphorus on a large block of limestone was investigated using deionized water (DIW) and seawater. The limestone had a high affinity to adsorb phosphorus in DIW. Phosphate adsorption was significantly less in seawater, and more phosphorus was desorbed in the seawate...

  9. Absorption and desorption mass transfer rates in chemically enhanced reactive systems. Part I : Chemical enhancement factors

    NARCIS (Netherlands)

    Hamborg, Espen S.; Versteeg, Geert F.

    2012-01-01

    The chemical enhancement factors have been measured in a controlled environment for absorption and desorption mass transfer processes in aqueous 2.0 M MDEA solutions at temperatures of 298.15, 313.15, and 333.15 K and the loading of CO2 ranging from 0 to 0.8 in a batch-operated stirred tank reactor.

  10. Laser Infrared Desorption Spectroscopy to Detect Complex Organic Molecules on Icy Planetary Surfaces

    Science.gov (United States)

    Sollit, Luke S.; Beegle, Luther W.

    2008-01-01

    Laser Desorption-Infrared Spectroscopy (LD-IR) uses an IR laser pulse to desorb surface materials while a spectrometer measures the emission spectrum of the desorbed materials (Figure 1). In this example, laser desorption operates by having the incident laser energy absorbed by near surface material (10 microns in depth). This desorption produces a plume that exists in an excited state at elevated temperatures. A natural analog for this phenomenon can be observed when comets approach the sun and become active and individual molecular emission spectra can be observed in the IR [1,2,3,4,5]. When this occurs in comets, the same species that initially emit radiation down to the ground state are free to absorb it, reducing the amount of detectable emission features. The nature of our technique results in absorption not occurring, because the laser pulse could easily be moved away form the initial desorption plume, and still have better spatial resolution then reflectance spectroscopy. In reflectance spectroscopy, trace components have a relatively weak signal when compared to the entire active nature of the surface. With LDIR, the emission spectrum is used to identify and analyze surface materials.

  11. SORPTION AND DESORPTION OF CADMIUM BY DIFFERENT FRACTIONS OF BIOSOLIDS - AMENDED SOILS

    Science.gov (United States)

    Series of Cd sorption and desorption experiments were conducted on different fractions of soils amended with biosolids, Cd-salt, and unamended soils (control) to test the hypothesize that not only organic but also inorganic fraction in biosolids controls the metal availability in...

  12. Electric field induced desorption of bacteria from a conditioning film covered substratum

    NARCIS (Netherlands)

    Poortinga, AT; Smit, J; van der Mei, HC; Busscher, HJ

    2001-01-01

    Desorption of three oral bacterial strains from a salivary conditioning film on an indium tin oxide electrode during application of a positive (bacterial adhesion to the anode) or a negative electric current was studied in a parallel plate flow chamber. Bacterial adhesion was from a flowing suspensi

  13. Description of the phosphorus sorption and desorption processes in lowland peaty clay soils

    NARCIS (Netherlands)

    Schoumans, O.F.

    2013-01-01

    To determine phosphorus (P) losses from agricultural land to surface water, information is needed about the behavior of P in soils. In this study, the sorption and desorption characteristics of lowland peaty clay soils are described based on experimental laboratory studies. The maximum P sorption ca

  14. Bioaerosol detection by aerosol TOF-mass spectrometry: Application of matrix assisted laser desorption/ionisation

    NARCIS (Netherlands)

    Wuijckhuijse, A.L. van; Stowers, M.A.; Kientz, Ch.E.; Marijnissen, J.C.M.; Scarlett, B.

    2000-01-01

    In previous publications the use of an aerosol time of flight mass spectrometer was reported for the on-line measurements of aerosols (Weiss 1997, Kievit 1995). The apparatus is capable of measuring the size as well as the chemical composition, by the use of Laser Desorption/Ionisation (LDI), of an

  15. Doubling Fluctuation-Enhanced Sensing Information by Separating Adsorption-Desorption and Difussive Fluctuations

    CERN Document Server

    Schmera, Gabor

    2008-01-01

    We analyze a (symmetrical) two-sensor arrangement with a joint boundary line between the sensors for fluctuation-enhanced sensing. We show a way to separate the adsorption-desorption signal components from the diffusive signal component. Thus the method generates two independent output spectra which doubles the sensor information for pattern recognition.

  16. Identification of Bacteria Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

    Science.gov (United States)

    Kedney, Mollie G.; Strunk, Kevin B.; Giaquinto, Lisa M.; Wagner, Jennifer A.; Pollack, Sidney; Patton, Walter A.

    2007-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS or simply MALDI) has become ubiquitous in the identification and analysis of biomacromolecules. As a technique that allows for the molecular weight determination of otherwise nonvolatile molecules, MALDI has had a profound impact in the molecular…

  17. Influence of Organic Amendments on Adsorption, Desorption and Leaching of Methiopyrisulfuron in Soils

    Institute of Scientific and Technical Information of China (English)

    WU Chun-xian; NIE Guo; ZHANG Zhong-ming; WANG Guang-cheng; GAO Li-ming; WANG Jin-jun

    2013-01-01

    Methiopyrisulfuron is a novel sulfonylurea herbicide with good activity for annual broadleaf and gramineal weeds control. Present study was to investigate the effects of organic amendments (including peat (PE), sewage sludge (SS), and humic acid (HA)) on adsorption, desorption and leaching of methiopyrisulfuron in soils. The batch equilibration technique was applied for adsorption-desorption experiments and the leaching was tested through soil column simulated experiments under laboratory conditions. The Freundlich model may well describe adsorption-desorption of methiopyrisulfuron on organic amendments, the natural soil, and amended soils. Organic amendments could not only greatly increase the adsorption capacity of methiopyrisulfuron, but also significantly enhance the hysteresis of desorption of methiopyrisulfuron. The correlations between Kf-ads and organic matter content of amended soils were significant, and the correlations between H and soil organic matter in amended soils with PE, SS, and HA were significant too. The results of soil column experiments indicated that organic amendments greatly decreased leaching of methiopyrisulfuron. This study suggested that PE, SS, and HA could greatly influence environmental behavior of methiopyrisulfuron in soils. Use of organic amendments might be an effective management practice for controlling potential pollution of methiopyrisulfuron to environment.

  18. Decomposition of thin titanium deuteride films; thermal desorption kinetics studies combined with microstructure analysis

    NARCIS (Netherlands)

    Lisowski, Wojciech; Keim, Enrico G.; Kaszkur, Zbigniew; Smithers, Mark A.

    2008-01-01

    The thermal evolution of deuterium from thin titanium films, prepared under UHV conditions and deuterated in situ at room temperature, has been studied by means of thermal desorption mass spectrometry (TDMS) and a combination of scanning electron microscopy (SEM), transmission electron microscopy (T

  19. Effects of surface coordination on the temperature-programmed desorption of oxalate from goethite

    Energy Technology Data Exchange (ETDEWEB)

    Boily, Jean F.; Szanyi, Janos; Felmy, Andrew R.

    2007-11-15

    The temperature-programmed desorption (TPD) of weakly-bound, hydrogen-bonded and metal-bonded oxalate complexes at the goethite surface was investigated in the 300-900 K range with concerted Fourier Transform Infrared (FTIR) measurements (TPD-FTIR). These reactions took place with the concomitant dehydroxylation reaction of goethite to hematite and decarbonation of bulk-occluded carbonate. The measurements revealed three important stages of desorption. Stage I (300-440 K) corresponds to the desorption of weakly-and/or un-bound oxalate molecules in the goethite powder with a thermal decomposition reaction pathway characteristic of oxalic acid. Stage II (440-520 K) corresponds to a thermally-driven dehydration of hydrogen-bonded surface complexes, leading to a partial desorption via oxalic acid thermal decomposition pathways and to a partial conversion to metal-bonded surface complexes. This latter mechanism led to the increase in FTIR bands characteristic of these complexes. Finally, Stage III (520-660 K) corresponds to the thermal decomposition of the metal-bonded oxalate complex, proceeding through a 2 electron reduction pathway.

  20. Desorption of Water from Distinct Step Types on a Curved Silver Crystal

    Directory of Open Access Journals (Sweden)

    Jakrapan Janlamool

    2014-07-01

    Full Text Available We have investigated the adsorption of H2O onto the A and B type steps on an Ag single crystal by temperature programmed desorption. For this study, we have used a curved crystal exposing a continuous range of surface structures ranging from [5(111 × (100] via (111 to [5(111 × (110]. LEED and STM studies verify that the curvature of our sample results predominantly from monoatomic steps. The sample thus provides a continuous array of step densities for both step types. Desorption probed by spatially-resolved TPD of multilayers of H2O shows no dependence on the exact substrate structure and thus confirms the absence of thermal gradients during temperature ramps. In the submonolayer regime, we observe a small and linear dependence of the desorption temperature on the A and B step density. We argue that such small differences are only observable by means of a single curved crystal, which thus establishes new experimental benchmarks for theoretical calculation of chemically accurate binding energies. We propose an origin of the observed behavior based on a “two state” desorption model.

  1. Modelling of the Absorption and Desorption Process of Chemical Heat Pumps

    Institute of Scientific and Technical Information of China (English)

    Gui-PingLin; Xiu-GanYuan

    1993-01-01

    A simple model for the desorption and absorption process of the chemical heat pump is presented in this paper .It is based on the assumption of a definite reaction front.The results from this model are compared with those obtained by finite difference method and it is observed that there is almost no difference between them.

  2. Laser Desorption Mass Spectrometry for High Throughput DNA Analysis and Its Applications

    Energy Technology Data Exchange (ETDEWEB)

    Allman, S.L.; Chen, C.H.; Golovlev, V.V.; Isola, N.R.; Matteson, K.J.; Potter, N.T.; Taranenko, N.I.

    1999-01-23

    Laser desorption mass spectrometry (LDMS) has been developed for DNA sequencing, disease diagnosis, and DNA Fingerprinting for forensic applications. With LDMS, the speed of DNA analysis can be much faster than conventional gel electrophoresis. No dye or radioactive tagging to DNA segments for detection is needed. LDMS is emerging as a new alternative technology for DNA analysis.

  3. Interactions on external MOF surfaces: desorption of water and ethanol from CuBDC nanosheets.

    Science.gov (United States)

    Elder, Alexander C; Aleksandrov, Alexandr B; Nair, Sankar; Orlando, Thomas M

    2017-09-06

    The external surfaces of metal-organic framework (MOF) materials are difficult to experimentally isolate due to the high porosities of these materials. MOF surface surrogates in the form of copper benzenedicarboxylate (CuBDC) nanosheets were synthesized using a bottom-up approach and the surface interactions of water and ethanol were investigated by temperature programmed desorption (TPD). A method of analysis of diffusion-influenced TPD was developed to measure the kinetic desorption properties of these porous materials. This approach also allows the extraction of diffusion coefficients from TPD data. Water desorbs from CuBDC nanosheets with activation energies of 44±2 kJ/mol at edge sites and 58 ± 1 kJ/mol at internal and surface sites. Ethanol desorbs with activation energies of 58 ± 1 kJ/mol at internal sites and 66 ± 0.4 kJ/mol at external surface sites. Co-adsorption of water and ethanol was also investigated. The presence of ethanol was found to inhibit the desorption of water that results in a water desorption process with an activation energy of 68 ± 0.7.

  4. Adsorption, desorption and bioregeneration in the treatment of 2-chlorophenol with activated carbon.

    Science.gov (United States)

    Aktaş, Ozgür; Ceçen, Ferhan

    2007-03-22

    This study aims to clarify the effect of activated carbon type on the extent of adsorbability, desorbability, and bioregenerability in the treatment of 2-chlorophenol. Four different activated carbon types; thermally activated and chemically activated powdered carbons (PAC), and their granular countertypes (GAC) with similar physical characteristics were used. Thermally activated carbons adsorbed 2-chlorophenol much better than chemically activated ones. However, adsorption was more reversible in the case of chemically activated ones. The use of powdered and granular activated carbon countertypes resulted in comparable adsorption and desorption characteristics. For each activated carbon type, 2-chlorophenol exhibited higher adsorbability and lower desorbability than phenol. Biodegradation of 2-chlorophenol took place very slowly when it was used as the sole carbon source in acclimated and non-acclimated activated sludges. Bioregeneration occurred only via desorption due to an initial concentration gradient and no further desorption took place due to low biodegradability. Bioregeneration of activated carbon loaded with 2-chlorophenol was not a suitable option when 2-chlorophenol was the only carbon source. It is suggested to remove 2-chlorophenol via adsorption onto activated carbon rather than applying biological treatment. Also in such cases, the use of thermally activated carbons with higher adsorption and lower desorption capacities is recommended rather than chemically activated carbons.

  5. Plasma physics and engineering

    CERN Document Server

    Fridman, Alexander

    2011-01-01

    Part I: Fundamentals of Plasma Physics and Plasma ChemistryPlasma in Nature, in the Laboratory, and in IndustryOccurrence of Plasma: Natural and Man MadeGas DischargesPlasma Applications, Plasmas in IndustryPlasma Applications for Environmental ControlPlasma Applications in Energy ConversionPlasma Application for Material ProcessingBreakthrough Plasma Applications in Modern TechnologyElementary Processes of Charged Species in PlasmaElementary Charged Particles in Plasma and Their Elastic and Inelastic CollisionsIonization ProcessesMechanisms of Electron Losses: The Electron-Ion RecombinationEl

  6. The effect of chars and their water extractable organic carbon (WEOC) fractions on atrazine adsorption-desorption processes

    Science.gov (United States)

    Cavoski, I.; Jablonowski, N.; Burauel, P.; Miano, T.

    2012-04-01

    Chars are carbonaceous material produced from different type of biomass by pyrolysis. They are known as highly effective adsorbents for atrazine therefore limiting its degradation and its diffusion into the aqueous phase. The aim of the present work is to study the effects of different chars and char's derived WEOC on atrazine sorption-desorption processes. The five chars been used in this study derived from: 1) fast pyrolysis from hard wood (FP1); 2) flash pyrolysis from soft wood (FP2); 3) slow pyrolysis from deciduous wood (CC); 4) gasification from deciduous wood (GC) and 5) the market, purchased as activated charcoal standard (AC). Short-term batch equilibration tests were conducted to assess the sorption-desorption behavior of 14C-labeled atrazine on the chars, with a special focus on the desorption behavior using successive dilution method with six consecutive desorption step. Chars and their WEOC were physically and chemically characterized. Results demonstrate that biomass and pyrolysis process used to produce chars affect their physical and chemical properties, and atrazine adsorption-desorption behavior. Atrazine desorption resulted from the positive and competitive interactions between WEOC and chars surfaces. WEOC pool play important role in atrazine adsorption-desorption behavior. FP1 and FP2 with higher concentration of WEOC showed higher desorption rates, whereas GC, CC and AC with insignificant WEOC concentration strongly adsorb atrazine with low desorption rates. According to our results, when high WEOC pools chars are concerned, an increase in atrazine desorption can be observed but further studies would help in confirming the present results.

  7. Monte Carlo simulations of temperature-programmed and isothermal desorption from single-crystal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lombardo, S.J. (California Inst. of Tech., Pasadena, CA (USA). Dept. of Chemical Engineering Lawrence Berkeley Lab., CA (USA))

    1990-08-01

    The kinetics of temperature-programmed and isothermal desorption have been simulated with a Monte Carlo model. Included in the model are the elementary steps of adsorption, surface diffusion, and desorption. Interactions between adsorbates and the metal as well as interactions between the adsorbates are taken into account with the Bond-Order-Conservation-Morse-Potential method. The shape, number, and location of the TPD peaks predicted by the simulations is shown to be sensitive to the binding energy, coverage, and coordination of the adsorbates. In addition, the occurrence of lateral interactions between adsorbates is seen to strongly effect the distribution of adsorbates is seen to strongly effect the distribution of adsorbates on the surface. Temperature-programmed desorption spectra of a single type of adsorbate have been simulated for the following adsorbate-metal systems: CO on Pd(100); H{sub 2} on Mo(100); and H{sub 2} on Ni(111). The model predictions are in good agreement with experimental observation. TPD spectra have also been simulated for two species coadsorbed on a surface; the model predictions are in qualitative agreement with the experimental results for H{sub 2} coadsorbed with strongly bound atomic species on Mo(100) and Fe(100) surfaces as well as for CO and H{sub 2} coadsorbed on Ni(100) and Rh(100) surfaces. Finally, the desorption kinetics of CO from Pd(100) and Ni(100) in the presence of gas-phase CO have been examined. The effect of pressure is seen to lead to an increase in the rate of desorption relative to the rate observed in the absence of gas-phase CO. This increase arises as a consequence of higher coverages and therefore stronger lateral interactions between the adsorbed CO molecules.

  8. Preliminary exploration of the relationships between soil characteristics and PAH desorption and biodegradation.

    Science.gov (United States)

    Hwang, Sangchul; Cutright, Teresa J

    2004-01-01

    Desorption and biodegradation of pyrene (PYR) were investigated and their relationships to soil characteristics were addressed. The results indicated that maximum achievable desorption was 30.2, 10.4, and 1.0 mg/kg for soils that had 1.7, 2.2, and 4.4 wt.% of expandable clays (smectite and vermiculite), respectively. Neither dissolved organic matter (DOM) nor total clay amounts made a good prediction of the desorption trend. Subsequently, the ease of desorption facilitated a faster aqueous biodegradation rate. The slowest aqueous biodegradation rate, 0.02 l/h, was achieved for the soil system that had the greatest amount of expandable clays, whereas the soil containing 1.7% expandable clays only achieved 0.73 l/h. The soil with 2.2% expandable clays depicted 0.41 l/h of aqueous biodegradation rate. A good linear correlation was obtained between maximum achievable desorption and aqueous biodegradation rate (R(2)=0.92). Soil analysis revealed that the total (soil+water) biodegradation reached was 65%, 78.3%, and 81.8% of the initial concentration (100 mg/kg) for the sandy clay loam (Colombian), sandy loam (Ohio), and silty loam (New Mexico) soils, respectively. This biodegradation extent was also in good agreement of expandable clay amount. Although aqueous PYR bioavailability was limited due to the strong association with the expandable clays, microbial movement and adhesion to those clays seemed to result in a great extent of the soil-phase biodegradation.

  9. Desorption, partitioning, and dechlorination characteristics of PCBs in sediments in interaction with reactive activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyeok, E-mail: hchoi@uta.edu [Department of Civil Engineering, The University of Texas at Arlington, 416 Yates Street, Arlington, TX 76019-0308 (United States); Environmental and Earth Sciences Program, The University of Texas at Arlington, 500 Yates Street, Arlington, TX 76019-0049 (United States); Lawal, Wasiu [Environmental and Earth Sciences Program, The University of Texas at Arlington, 500 Yates Street, Arlington, TX 76019-0049 (United States); Al-Abed, Souhail R. [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268 (United States)

    2015-04-28

    Highlights: • Problematic aged real PCBs-contaminated sediment (WHS) was examined. • Performance of reactive activated carbon (RAC) impregnated with Pd–ZVI was tested. • Fate and transport of PCBs bound to WHS in the presence of RAC was fully traced. • Direct mixing configuration was compared with compartment configuration. • Results reflected real world complexities associated with slow desorption of PCBs. - Abstract: Sediment (WHS) in Waukegan Harbor, Illinois, heavily contaminated and aged with polychlorinated biphenyls (PCBs), was treated with reactive activated carbon (RAC) impregnated with palladized iron nanoparticles. Lab test proceeded in a direct mixing configuration of RAC and WHS. A compartment configuration, where RAC was physically separated from WHS, was also designed to trace the sequential transport and fate of PCBs, including desorption, adsorption, dechlorination, and re-partitioning. PCBs, once desorbed from WHS, were immediately sequestrated to RAC and subject to dechlorination. Direct mixing of WHS with RAC was one-order of magnitude more effective for dechlorination than compartment configuration. Compared to their desorption-followed by-adsorption route, direct physical contact of RAC with PCBs bound to WHS exhibited negligible contribution to the availability of PCBs for dechlorination reaction. Addition of RAC even in compartment configuration facilitated PCBs desorption from WHS. However, slow desorption of PCBs limited overall performance, resulting in a five-order of magnitude lower dechlorination yield when compared with treatment of purely aqueous PCBs. The low dechlorination yield reflected real world complexities in treating 3.19% organic carbon-containing WHS aged with PCBs for 40 years. These observations were further supported when compared with results on clean Cesar Creek sediment spiked with 2-chlorinated biphenyls.

  10. Magnetoresistive waves in plasmas

    Science.gov (United States)

    Felber, F. S.; Hunter, R. O., Jr.; Pereira, N. R.; Tajima, T.

    1982-10-01

    The self-generated magnetic field of a current diffusing into a plasma between conductors can magnetically insulate the plasma. Propagation of magnetoresistive waves in plasmas is analyzed. Applications to plasma opening switches are discussed.

  11. Laser desorption and time-of-flight mass spectrometry. Fundamentals .Applications; Desorption laser et spectrometrie de masse par temps de vol. Aspects fondamentaux. Applications

    Energy Technology Data Exchange (ETDEWEB)

    Chaurand, P.

    1994-11-01

    Time-of-flight mass spectrometry is a very powerful technique for the analysis of heavy molecular ions (100 000 u and more). The ejection in the gas phase and the ionization of these molecules is now possible through the MALDI technique (Matrix Assisted Laser Desorption Ionization). This technique consists in mixing the heavy molecules to be analysed with a organic matrix which absorbs at the wavelength of the laser. The necessary irradiance are of the order of 10{sup 6} W/cm{sup 2}. In these conditions we have shown that the mass resolutions are optimum and that the relative mass accuracies are of the order of 10{sup -4}. We have also demonstrated that the emission angle of the molecular ions in MALDI depends on the incident angle of the laser light. During the desorption process, the molecular ions are emitted in the opposite direction of the incident laser light. This effect is particularly important for the design of the accelerating stage of the time-of-flight spectrometers. Problems relative to the detection of these heavy molecular ions have been studied in details between 0.5 10{sup 4} m/s and 10{sup 5} m/s. The velocity threshold of the electronic emission is lower than the value of 0.5 10{sup 4} m/s. The relation between the electronic emission and the projectile velocity is complex. Finally, examples on mass identification of C{sub 60} molecules and derivated C{sub 60} are presented. Desorption methods are compared. (author). 32 refs., 34 figs.

  12. Processes for desorption from LiAlO sub 2 treated with H sub 2 as studied by temperature programmed desorption

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, A.K.

    1990-01-01

    The energetics and kinetics of the evolution of H{sub 2}O and H{sub 2} from LiAlO{sub 2} are being studied by the temperature programmed desorption technique. The concentrations of H{sub 2}, H{sub 2}O, N{sub 2}, and O{sub 2} in a helium stream during a temperature ramp are measured simultaneously with a mass spectrometer. Blank experiments with an empty sample tube showed that square wave spikes of H{sub 2} introduced into the helium gas stream were severely distorted by reaction with the tube walls. The tube could be stabilized, however, by sufficiently prolonged heat treatment with H{sub 2} so that H{sub 2} peaks would not be distorted up to approximately 923 K(650{degree}C). The amount of H{sub 2}adsorption/desorption is small compared to the amount of H{sub 2}O adsorption/desorption. After prolonged treatment with helium containing 990 ppm H{sub 2} at 400{degree}C, H{sub 2}O evolution into the He-H{sub 2} stream was observed during 473 to 1023 K (200 to 750{degree}C) ramps at rates of 2 or 5.6 K/min. The different peak shapes reflecting this process were deconvoluted to show that they are composites of only 2 or 3 reproducible processes. The activation energies and pre-exponential terms was evaluated. The different behavior originates in the differences among different surface sites for adsorption. The interpretation of higher temperature peaks (above 873 K (650{degree}C)) must still consider the possibility of contributions from interactions with steel walls. It was found that H{sub 2} enhances evolution of N{sub 2} from the steel. 1 tab., 6 figs., 11 refs.

  13. Electrosurgical plasmas

    Science.gov (United States)

    Stalder, Kenneth R.; McMillen, Donald F.; Woloszko, Jean

    2005-06-01

    Electrosurgical medical devices based on repetitively pulsed nonequilibrium micron-scale to millimetre-scale plasma discharges in saline solutions are described. The formation of vapour layers (bubbles) around active electrodes appears to be a common feature at moderate (<300 V rms) voltages, and dissociation, excitation and ionization of the vapour in these bubbles produces chemical conditions that are thought to be the source of beneficial tissue removal and treatment. Experimental data are discussed, as are the results of modelling efforts of the plasma chemistry. Hydroxyl radicals, hydrogen atoms and other species are observed spectroscopically and their interactions with collagen, a common component of tissue encountered in surgical situations, are considered. Several pathways by which hydroxyl radicals interacting with collagen can lead to tissue removal are discussed.

  14. Electrosurgical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stalder, Kenneth R; McMillen, Donald F; Woloszko, Jean [ArthroCare Corp., Sunnyvale, CA 94085-3523 (United States)

    2005-06-07

    Electrosurgical medical devices based on repetitively pulsed nonequilibrium micron-scale to millimetre-scale plasma discharges in saline solutions are described. The formation of vapour layers (bubbles) around active electrodes appears to be a common feature at moderate (<300 V rms) voltages, and dissociation, excitation and ionization of the vapour in these bubbles produces chemical conditions that are thought to be the source of beneficial tissue removal and treatment. Experimental data are discussed, as are the results of modelling efforts of the plasma chemistry. Hydroxyl radicals, hydrogen atoms and other species are observed spectroscopically and their interactions with collagen, a common component of tissue encountered in surgical situations, are considered. Several pathways by which hydroxyl radicals interacting with collagen can lead to tissue removal are discussed.

  15. Plasma physics

    CERN Document Server

    Cairns, R A

    1985-01-01

    This book is intended as an introduction to plasma physics at a level suitable for advanced undergraduates or beginning postgraduate students in physics, applied mathematics or astrophysics. The main prerequisite is a knowledge of electromagnetism and of the associated mathematics of vector calculus. SI units are used throughout. There is still a tendency amongst some plasma physics researchers to· cling to C.g.S. units, but it is the author's view that universal adoption of SI units, which have been the internationally agreed standard since 1960, is to be encouraged. After a short introductory chapter, the basic properties of a plasma con­ cerning particle orbits, fluid theory, Coulomb collisions and waves are set out in Chapters 2-5, with illustrations drawn from problems in nuclear fusion research and space physics. The emphasis is on the essential physics involved and (he theoretical and mathematical approach has been kept as simple and intuitive as possible. An attempt has been made to draw attention t...

  16. Plasma pharmacy - physical plasma in pharmaceutical applications.

    Science.gov (United States)

    von Woedtke, Th; Haertel, B; Weltmann, K-D; Lindequist, U

    2013-07-01

    During the last years the use of physical plasma for medical applications has grown rapidly. A multitude of findings about plasma-cell and plasma-tissue interactions and its possible use in therapy have been provided. One of the key findings of plasma medical basic research is that several biological effects do not result from direct plasma-cell or plasma-tissue interaction but are mediated by liquids. Above all, it was demonstrated that simple liquids like water or physiological saline, are antimicrobially active after treatment by atmospheric pressure plasma and that these effects are attributable to the generation of different low-molecular reactive species. Besides, it could be shown that plasma treatment leads to the stimulation of specific aspects of cell metabolism and to a transient and reversible increase of diffusion properties of biological barriers. All these results gave rise to think about another new and innovative field of medical plasma application. In contrast to plasma medicine, which means the direct use of plasmas on or in the living organism for direct therapeutic purposes, this field - as a specific field of medical plasma application - is called plasma pharmacy. Based on the present state of knowledge, most promising application fields of plasma pharmacy might be: plasma-based generation of biologically active liquids; plasma-based preparation, optimization, or stabilization of - mainly liquid - pharmaceutical preparations; support of drug transport across biological barriers; plasma-based stimulation of biotechnological processes.

  17. Tungsten nitride coatings obtained by HiPIMS as plasma facing materials for fusion applications

    Science.gov (United States)

    Tiron, Vasile; Velicu, Ioana-Laura; Porosnicu, Corneliu; Burducea, Ion; Dinca, Paul; Malinský, Petr

    2017-09-01

    In this work, tungsten nitride coatings with nitrogen content in the range of 19-50 at% were prepared by reactive multi-pulse high power impulse magnetron sputtering as a function of the argon and nitrogen mixture and further exposed to a deuterium plasma jet. The elemental composition, morphological properties and physical structure of the samples were investigated by Rutherford backscattering spectrometry, atomic force microscopy and X-ray diffraction. Deuterium implantation was performed using a deuterium plasma jet and its retention in nitrogen containing tungsten films was investigated using thermal desorption spectrometry. Deuterium retention and release behaviour strongly depend on the nitrogen content in the coatings and the films microstructure. All nitride coatings have a polycrystalline structure and retain a lower deuterium level than the pure tungsten sample. Nitrogen content in the films acts as a diffusion barrier for deuterium and leads to a higher desorption temperature, therefore to a higher binding energy.

  18. Evaluation of enthalpy change due to hydrogen desorption for lithium amide/imide system by differential scanning calorimetry

    OpenAIRE

    2008-01-01

    Enthalpy change (ΔH) due to hydrogen desorption (H-desorption) for the lithium amide/imide system was evaluated by differential scanning calorimetry (DSC) measurement. In order to obtain the accurate and precise value of ΔH, we have paid special attention to following two points for correcting raw experimental data. One is to determine a cell constant of DSC equipment, which was evaluated by using the TiO2-doped MgH2 compound as a reference because of its quite similar hydrogen desorption pro...

  19. A photoluminescence study of indium desorption from strained Ga sub 1-x In sub x As/GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Emeny, M.T.; Whitehouse, C.R. (Royal Signals and Radar Establishment, Great Malvern (UK)); Howard, L.K.; Lambkin, J.D. (Strained Layer Structures Group, Univ. of Surrey, Guildford (UK)); Homewood, K.P. (Dept. of Electronic and Electrical Engineering, Univ. of Surrey, Guildford (UK))

    1991-05-01

    In this paper we present detailed measurements of the thermal desorption rates of indium from strained GaInAs grown off a GaAs substrate. We have made these measurements by monitoring the photoluminescence (PL) of the groundstate emission from strained quantum wells. We show that this method can be an accurate and highly sensitive technique for measuring desorption rates. The measurements have been made as a function of composition and arsenic overpressure. A simple model for the indium incorporation is developed and an activation energy for the desorption process has been obtained. (orig.).

  20. Surface structure and surface kinetics of InN grown by plasma-assisted atomic layer epitaxy: A HREELS study

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, Ananta R., E-mail: aacharya@georgiasouthern.edu, E-mail: anantaach@gmail.com [Department of Physics, Georgia Southern University, Statesboro, Georgia 30460 (United States); Thoms, Brian D. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Nepal, Neeraj [American Association for Engineering Education, 1818 N Street NW, Washington, DC 20034 (United States); Eddy, Charles R. [Electronics Science and Technology Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States)

    2015-03-15

    The surface bonding configuration and kinetics of hydrogen desorption from InN grown by plasma-assisted atomic layer epitaxy have been investigated. High resolution electron energy loss spectra exhibited loss peaks assigned to a Fuchs–Kliewer surface phonon, N-N and N-H surface species. The surface N-N vibrations are attributed to surface defects. The observation of N-H but no In-H surface species suggested N-terminated InN. Isothermal desorption data were best fit by the first-order desorption kinetics with an activation energy of (0.88 ± 0.06) eV and pre-exponential factor of (1.5 ± 0.5) × 10{sup 5 }s{sup −1}.

  1. Surface modification of tungsten and tungsten-tantalum alloys exposed to high-flux deuterium plasma and its impact on deuterium retention

    NARCIS (Netherlands)

    Zayachuk, Y.; Hoen, M. H. J. 't; van Emmichoven, P. A. Zeijlma; Terentyev, D.; Uytdenhouwen, I.; Van Oost, G.

    2013-01-01

    Samples of tungsten and tungsten-tantalum alloy (with 5 mass per cent of Ta) were exposed to high-flux deuterium plasma at different fluences. The surface modification was studied with scanning electron microscopy, and deuterium retention was measured by thermal desorption spectroscopy (TDS). In the

  2. Molecular desorption of stainless steel vacuum chambers irradiated with 42 MeV/u lead ions

    CERN Document Server

    Mahner, E; Laurent, Jean Michel; Madsen, N

    2003-01-01

    In preparation for the heavy ion program of the Large Hadron Collider at CERN, accumulation and cooling tests with lead ion beams have been performed in the Low Energy Antiproton Ring. These tests have revealed that due to the unexpected large outgassing of the vacuum system, the dynamic pressure of the ring could not be maintained low enough to reach the required beam intensities. To determine the actions necessary to lower the dynamic pressure rise, an experimental program has been initiated for measuring the molecular desorption yields of stainless steel vacuum chambers by the impact of 4.2 MeV/u lead ions with the charge states +27 and +53. The test chambers were exposed either at grazing or at perpendicular incidence. Different surface treatments (glow discharges, nonevaporable getter coating) are reported in terms of the molecular desorption yields for H/sub 2 /, CH/sub 4/, CO, Ar, and CO/sub 2/. (16 refs).

  3. Forced desorption of semiflexible polymers, adsorbed and driven by molecular motors

    CERN Document Server

    Chaudhuri, Abhishek

    2014-01-01

    We formulate and characterize a model to describe dynamics of semiflexible polymers in the presence of activity due to motor proteins attached irreversibly to a substrate, and a transverse pulling force acting on one end of the filament. The stochastic binding-unbinding of the motor proteins and their ability to move along the polymer, generates active forces. As the pulling force reaches a threshold value, the polymer eventually desorbs from the substrate. We present a mean field theory that predicts increase in desorption force with polymer bending rigidity, active velocity and processivity of the motor proteins. Performing molecular dynamics simulations of the polymer in presence of a Langevin heat bath, and stochastic motor activity we obtain desorption phase diagrams that show good agreement with theory. With increase in pulling force, the polymer undergoes a first order phase transition from mostly adsorbed to fully desorbed state via a regime of coexistence where the steady state dynamics of the polyme...

  4. Desorption Dynamics of Heavy Alkali Metal Atoms (Rb, Cs) off the Surface of Helium Nanodroplets

    CERN Document Server

    von Vangerow, J; Stienkemeier, F; Mudrich, M; Leal, A; Mateo, D; Hernando, A; Barranco, M; Pi, M

    2014-01-01

    We present a combined ion imaging and density functional theory study of the dynamics of the desorption process of rubidium and cesium atoms off the surface of helium nanodroplets upon excitation of the perturbed $6s$ and $7s$ states, respectively. Both experimental and theoretical results are well represented by the pseudodiatomic model for effective masses of the helium droplet in the desorption reaction of m_eff/m_He~10 (Rb) and 13 (Cs). Deviations from this model are found for Rb excited to the 6p state. Photoelectron spectra indicate that the dopant-droplet interaction induces relaxation into low-lying electronic states of the desorbed atoms in the course of the ejection process.

  5. Hydrogen solubility and diffusion in austenitic stainless steels studied with thermal desorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yagodzinskyy, Y.; Todoshchenko, O.; Papula, S.; Haenninen, H. [Laboratory of Engineering Materials, School of Science and Technology, Aalto University, Espoo (Finland)

    2011-01-15

    Hydrogen solubility and diffusion in austenitic stainless steels, namely AISI 310, AISI 301LN and AISI 201, are studied with thermal desorption spectroscopy (TDS) after electrochemical potentiostatic hydrogen pre-charging. Temperature dependencies of hydrogen desorption for all studied steels manifest a complex main peak caused by hydrogen releasing from the steel lattice by diffusion. Depending on the steel and heating rate the peak is situated from 350 to 500 K and its shape reflects a specific of hydrogen diffusion in stainless steels, which are multicomponent alloys. Analysis of the TDS curves is based on the hydrogen diffusion model taking into account trapping of hydrogen atoms in the energetically deep interstitial positions in the steel crystal lattice. Diffusion coefficient of hydrogen and its total content after the same charging procedure are obtained from the TDS curves and compared for the studied steels. (Copyright copyright 2011 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Microsystem with integrated capillary leak to mass spectrometer for high sensitivity temperature programmed desorption

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Jensen, Søren; Hansen, Ole

    2004-01-01

    Temperature programmed desorption (TPD) is a method for obtaining information about quantities and binding properties of adsorbed species on a surface. A microfabricated flow system for TPD with an integrated capillary leak to a mass spectrometer is presented. The use of an integrated capillary l.......5 cm2 of platinum foil gives a clear desorption peak. By using the microfabricated flow system, TPD experiments can be performed in a carrier gas with a sensitivity approaching that of TPD experiments in vacuum. ©2004 American Institute of Physics...... leak minimizes dead volumes in the system, resulting in increased sensitivity and reduced response time. These properties make the system ideal for TPD experiments in a carrier gas. With CO desorbing from platinum as model system, it is shown that CO desorbing in 105 Pa of argon from as little as 0...

  7. Organometallics and quaternary ammonium salts affect calcium ion desorption from lecithin liposome membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kral, T.E.; Kuczera, J.; Przestalski, S. [Dept. of Physics and Biophysics, Agricultural Univ., Wroclaw (Poland)

    2001-06-01

    The objective of the present work was to compare the effects of groups of tin and lead organometallic compounds and their mixtures with amphiphilic quaternary ammonium salts (QAS) on the process of calcium ion desorption from lecithin liposome membranes, as dependent on the properties of the hydrophilic and hydrophobic parts of QAS. In the investigations the method of radioactive labels was applied. Synergism and antagonism in the action of both groups of compounds were found. The effectiveness of the cooperation depended more on chain length of QAS compounds than on the size and polarity of their hydrophobic parts. The most effective of all compounds studied was a the mixture of benzyldimethylammonium chloride in a mixture with tripropyltin. Since the rate of calcium desorption proved to be a good measure of efficacy of biologically active surfactants, it seems that the conclusions reached in this paper may be useful for choosing compounds which are able to decontaminate the environment polluted with heavy metals. (orig.)

  8. Theoretical study of simultaneous water and VOCs adsorption and desorption in a silica gel rotor

    DEFF Research Database (Denmark)

    Zhang, G.; Zhang, Y.F.; Fang, Lei

    2008-01-01

    One-dimensional partial differential equations were used to model the simultaneous water and VOC (Volatile Organic Compound) adsorption and desorption in a silica gel rotor which was recommended for indoor air cleaning. The interaction among VOCs and moisture in the adsorption and desorption...... by the temperatures of the rotor and the air stream. The VOC transfer equations were solved by discretizing them into explicit up-wind finite differential equations. The model was validated with experimental data. The calculated results suggested that the regeneration time designed for dehumidification may...... process was neglected in the model as the concentrations of VOC pollutants in typical indoor environment were much lower than that of moisture and the adsorbed VOCs occupied only a minor portion of adsorption capacity of the rotor. Consequently VOC transfer was coupled with heat and moisture transfer only...

  9. Hydrogen absorption-desorption properties of UZr sub 0 sub . sub 2 sub 9 alloy

    CERN Document Server

    Shuai Mao Bing; WangZhenHong; Zhang Yi Tao

    2001-01-01

    Hydrogen absorption-desorption properties of UZr sub 0 sub . sub 2 sub 9 alloy are investigated in detail at hydrogen pressures up to 0.4 MPa and over the temperature range of 300 to 723 K. It absorbs hydrogen up to 2.3 H atoms per F.U. (formula unit) by only one-step reaction and hence each desorption isotherm has a single plateau over nearly the whole hydrogen composition range. The enthalpy and entropy changes of the dissociation reaction are of -78.9 kJ centre dot mol sup - sup 1 H sub 2 and 205.3 J centre dot(K centre dot mol H sub 2) sup - sup 1 , respectively. The alloy shows high durability against powdering upon hydrogenation and may have good heat conductivity. It is predicted that UZr sub 0 sub . sub 2 sub 9 alloy may be a suitable material for tritium treatment and storage

  10. Dust as interstellar catalyst - II. How chemical desorption impacts the gas

    CERN Document Server

    Cazaux, S; Dulieu, F; Hocuk, S

    2015-01-01

    Context. Interstellar dust particles, which represent 1% of the total mass, are recognized to be very powerful interstellar catalysts in star-forming regions. The presence of dust can have a strong impact on the chemical composition of molecular clouds. While observations show that many species that formed onto dust grains populate the gas phase, the process that transforms solid state into gas phase remains unclear. Aims. The aim of this paper is to consider the chemical desorption process, i.e. the process that releases solid species into the gas phase, in astrochemical models. These models allow determining the chemical composition of star-forming environments with an accurate treatment of the solid-phase chemistry. Methods. In paper I we derived a formula based on experimental studies with which we quantified the efficiencies of the chemical desorption process. Here we extend these results to astrophysical conditions. Results. The simulations of astrophysical environments show that the abundances of gas-p...

  11. Angular distributions of photon stimulated desorption in a vacuum duct observed by using a unidirectional detector

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, M.; Matumoto, M.; Ueda, S.

    1987-07-01

    Pressures in the vacuum duct of the electron storage rings depend on photodesorption. A multicapillary-type mass spectrometer was applied to observe local outgassing rates in the duct, in which the duct surfaces were irradiated by directly incident photons and/or by scattered photons. Local outgassing rates were nonuniform along the periphery of the duct. The desorption rates at the directly incident point were higher than at the other surfaces when photon dose was less than 200 mA h. At over 9000 mA h the rates at that point decreased more, while the desorption rates at the other surfaces decreased less. Angular distributions of photocurrent were also measured. The distributions were almost uniform except near the directly incident point.

  12. Desorption and biofiltration for the treatment of residual organic gases evolved in soil decontamination processes

    Energy Technology Data Exchange (ETDEWEB)

    Barona, A.; Elias, A.; Arias, R.; Acha, E.; Cano, I. [Department of Chemical and Environmental Engineering, University of the Basque Country, Bilbao (Spain)

    2007-11-15

    In order to analyze the combination of a rotary kiln and a biofilter in soil decontamination processes, a previously characterized soil was artificially contaminated with toluene, ethylbenzene or p-xylene. The desorption peak of the three compounds occurred very quickly at 20 C, and consequently, the outlet gas flow from the rotary kiln was initially divided into two different flows. One of them was reduced to a 1/9{sup th} fraction of the total flow to be treated in an independent biofiltration system specially acclimated to each contaminant. The sharp desorption peak observed for the three compounds at the outlet of the kiln involved a very high inlet concentration fed into the biofilters in a very short period of time (shorter than 3 h). Consequently, the removal efficiency for toluene was lower than 70 %. However, the removal efficiencies for ethylbenzene and xylene were always higher than 65 %. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  13. Kinetic Monte Carlo simulations of temperature programed desorption of O/Rh(111).

    Science.gov (United States)

    Franz, T; Mittendorfer, F

    2010-05-21

    We present a kinetic Monte Carlo simulation based on ab initio calculations for the thermal desorption of oxygen from a Rh(111) surface. Several models have been used for the parametrization of the interaction between the adsorbed atoms. We find that models based on a parametrization with only pairwise interactions have a relatively large error in the predicted adsorption energies. This error can be significantly reduced by including three- and four-body interactions. In addition, we find that a significant amount of atoms adsorb in a second adsorption site - the hcp-hollow site - at an elevated temperature. Consequently, only a many-body multisite model of the oxygen interactions yields appropriate desorption spectra for the full coverage range, while more simple models only capture the correct shape in the low-coverage case. Our parametrization allows us to predict the adsorption energies of an arbitrary configuration of adsorbates with a mean average error of less than 6 meV/atom.

  14. Large Scale Nanoparticle Screening for Small Molecule Analysis in Laser Desorption Ionization Mass Spectrometry.

    Science.gov (United States)

    Yagnik, Gargey B; Hansen, Rebecca L; Korte, Andrew R; Reichert, Malinda D; Vela, Javier; Lee, Young Jin

    2016-09-20

    Nanoparticles (NPs) have been suggested as efficient matrixes for small molecule profiling and imaging by laser-desorption ionization mass spectrometry (LDI-MS), but so far there has been no systematic study comparing different NPs in the analysis of various classes of small molecules. Here, we present a large scale screening of 13 NPs for the analysis of two dozen small metabolite molecules. Many NPs showed much higher LDI efficiency than organic matrixes in positive mode and some NPs showed comparable efficiencies for selected analytes in negative mode. Our results suggest that a thermally driven desorption process is a key factor for metal oxide NPs, but chemical interactions are also very important, especially for other NPs. The screening results provide a useful guideline for the selection of NPs in the LDI-MS analysis of small molecules.

  15. Organometallics and quaternary ammonium salts affect calcium ion desorption from lecithin liposome membranes.

    Science.gov (United States)

    Kral, T E; Kuczera, J; Przestalski, S

    2001-01-01

    The objective of the present work was to compare the effects of groups of tin and lead organometallic compounds and their mixtures with amphiphilic quaternary ammonium salts (QAS) on the process of calcium ion desorption from lecithin liposome membranes, as dependent on the properties of the hydrophilic and hydrophobic parts of QAS. In the investigations the method of radioactive labels was applied. Synergism and antagonism in the action of both groups of compounds were found. The effectiveness of the cooperation depended more on chain length of QAS compounds than on the size and polarity of their hydrophobic parts. The most effective of all compounds studied was a the mixture of benzyldimethylammonium chloride in a mixture with tripropyltin. Since the rate of calcium desorption proved to be a good measure of efficacy of biologically active surfactants, it seems that the conclusions reached in this paper may be useful for choosing compounds which are able to decontaminate the environment polluted with heavy metals.

  16. Hot electron mediated desorption rates calculated from excited state potential energy surfaces

    CERN Document Server

    Olsen, Thomas; Schiøtz, Jakob

    2008-01-01

    We present a model for Desorption Induce by (Multiple) Electronic Transitions (DIET/DIMET) based on potential energy surfaces calculated with the Delta Self-Consistent Field extension of Density Functional Theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various transition metal surfaces, and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system, with parameters obtained from the excited state potential energy surface, and show that this model can describe desorption dynamics in both the DIET and DIMET regime, and reproduce the power law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong.

  17. Development of Laser Desorption Imaging Mass Spectrometry Methods to Investigate the Molecular Composition of Latent Fingermarks

    Science.gov (United States)

    Lauzon, Nidia; Dufresne, Martin; Chauhan, Vinita; Chaurand, Pierre

    2015-06-01

    For a century, fingermark analysis has been one of the most important and common methods in forensic investigations. Modern chemical analysis technologies have added the potential to determine the molecular composition of fingermarks and possibly identify chemicals a suspect may have come into contact with. Improvements in analytical detection of the molecular composition of fingermarks is therefore of great importance. In this regard, matrix-assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) imaging mass spectrometry (IMS) have proven to be useful technologies for fingermark analysis. In these analyses, the choice of ionizing agent and its mode of deposition are critical steps for the identification of molecular markers. Here we propose two novel and complementary IMS approaches for endogenous and exogenous substance detection in fingermarks: sublimation of 2-mercaptobenzothiazol (2-MBT) matrix and silver sputtering.

  18. Study of desorption in a vapor dominated reservoir with fractal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Tudor, Monica; Horne, Roland N.; Hewett, Thomas A.

    1995-01-26

    This paper is an attempt to model well decline in a vapor dominated reservoir with fractal geometry. The fractal network of fractures is treated as a continuum with characteristic anomalous diffusion of pressure. A numerical solver is used to obtain the solution of the partial differential equation including adsorption in the fractal storage space. The decline of the reservoir is found to obey the empirical hyperbolic type relation when adsorption is not present. Desorption does not change the signature of the flow rate decline but shifts it on the time/flow rate axis. Only three out of six model parameters can be estimated from field data, due to the linear correlation between parameters. An application to real well data from The Geysers field is presented together with the estimated reservoir, fractal space and adsorption parameters. Desorption dominated flow is still a questionable approximation for flow in fractal objects.

  19. Desorption Dynamics of Rb_2 Molecules off the Surface of Helium Nanodroplets

    CERN Document Server

    Sieg, A; Stienkemeier, F; Dulieu, O; Mudrich, M

    2016-01-01

    The desorption dynamics of rubidium dimers (Rb_2) off the surface of helium nanodroplets induced by laser excitation is studied employing both nanosecond and femtosecond ion imaging spectroscopy. Similarly to alkali metal atoms, we find that the Rb_2 desorption process resembles the dissociation of a diatomic molecule. However, both angular and energy distributions of detected Rb_2^+ ions appear to be most crucially determined by the Rb_2 intramolecular degrees of freedom rather than by those of the Rb_2He_N complex. The pump-probe dynamics of Rb_2^+ is found to be slower than that of Rb^+ pointing at a weaker effective guest-host repulsion for excited molecules than for single atoms.

  20. Desorption dynamics of heavy alkali metal atoms (Rb, Cs) off the surface of helium nanodroplets.

    Science.gov (United States)

    von Vangerow, J; Sieg, A; Stienkemeier, F; Mudrich, M; Leal, A; Mateo, D; Hernando, A; Barranco, M; Pi, M

    2014-08-21

    We present a combined ion imaging and density functional theory study of the dynamics of the desorption process of rubidium and cesium atoms off the surface of helium nanodroplets upon excitation of the perturbed 6s and 7s states, respectively. Both experimental and theoretical results are well represented by the pseudodiatomic model for effective masses of the helium droplet in the desorption reaction of meff/mHe ≈ 10 (Rb) and 13 (Cs). Deviations from this model are found for Rb excited to the 6p state. Photoelectron spectra indicate that the dopant-droplet interaction induces relaxation into low-lying electronic states of the desorbed atoms in the course of the ejection process.

  1. Simultaneous adsorption/desorption of quaternary ammonium herbicides by acid vineyard soils

    Science.gov (United States)

    Conde Cid, Manuel; Paradelo Núñez, Remigio; Fernández Calviño, David; Nóvoa Muñoz, Juan Carlos; Arias Estévez, Manuel

    2017-04-01

    Competitive adsorption and desorption of three quaternary ammonium herbicides (paraquat, diquat, and difenzoquat) have been studied in four sandy-loam acid vineyard soils from NW Spain and Portugal. The soils present organic matter contents between 3 and 48 g kg-1 and copper contents ranging from 25 to 107 mg kg-1. Adsorption has been studied under equilibrium conditions in batch experiments, and kinetics were studied in a stirred-flow chamber. Adsorption and desorption followed a Freundlich model and kinetics were well described by the pseudo-first-order model. The retention capacity for the pesticides by the four soils followed the sequence: paraquat > diquat > difenzoquat. The different adsorption capacities of each soil were not related to pH, clay or organic matter contents, as could be expected, but rather to soil copper content. The results show that competition with copper for adsorption sites is an important factor in quaternary ammonium herbicides retention in soils with these characteristics.

  2. The thermal desorption of CO2 from amine carbamate solutions for the 13C isotope enrichment

    Science.gov (United States)

    Dronca, S.; Varodi, C.; Gligan, M.; Stoia, V.; Baldea, A.; Hodor, I.

    2012-02-01

    The CO2 desorption from amine carbamate in non-aqueous solvents is of major importance for isotopic enrichment of 13C. A series of experiments were carried out in order to set up the conditions for the CO2 desorption. For this purpose, a laboratory- scale plant for 13C isotope separation by chemical exchange between CO2 and amine carbamate was designed and used. The decomposition of the carbamate solution was mostly produced in the desorber and completed in the boiler. Two different-length desorbers were used, at different temperatures and liquid flow rates of the amine-non-aqueous solvent solutions. The residual CO2 was determined by using volumetric and gaschromatographic methods. These results can be used for enrichment of 13C by chemical exchange between CO2 and amine carbamate in nonaqueous solvents.

  3. Laser-induced desorption of overlayer films off a heated metal substrate

    Science.gov (United States)

    Gu, Xiang; Urbassek, Herbert M.

    2007-02-01

    The temperature-induced desorption of adsorbed overlayer films with thicknesses between 4 and 200 ML off a suddenly heated metal substrate is studied using molecular-dynamics simulation. We observe that the rapid heating vaporizes the surface-near part of the overlayer film. The initial heating-induced thermoelastic pressure and the vapor pressure in the vapor film drive the remaining film as a large relatively cold cluster away from the surface. In our simulations, the material present in the developing vapor film amounts to roughly 2 ML and is quite independent of the overlayer film thickness. For cluster thicknesses beyond 40 ML, the desorption time increases only little with film thickness, while the resulting cluster velocity decreases only slightly.

  4. Kinetics of hydrogen desorption from MgH2 and AlH3 hydrides

    Science.gov (United States)

    Terent'ev, P. B.; Gerasimov, E. G.; Mushnikov, N. V.; Uimin, M. A.; Maikov, V. V.; Gaviko, V. S.; Golovatenko, V. D.

    2015-12-01

    Kinetic parameters of the process of thermal decomposition of the MgH2 hydride (obtained by the method of the mechanoactivation of magnesium in a hydrogen atmosphere) and of the commercial AlH3 hydride have been studied upon the rapid heating in the range of temperatures of 150-510°C at hydrogen pressures of 0-2 atm. The time dependences of the amount of hydrogen released by the metal hydrides at different temperatures and pressures have been determined. It has been shown that the activation energies of the hydrogen desorption are 135 kJ/mol for MgH2 and 107 kJ/mol for AlH3. The maximum rates of hydrogen desorption from the investigated metal hydrides have been established, and the temperatures and initial pressures that ensure the maximum rate and maximum volume of the hydrogen release have been determined.

  5. Effect of Ultrasound on Desorption Equilibrium%超声场对氢键缔合体系解吸平衡的影响研究

    Institute of Scientific and Technical Information of China (English)

    秦炜; 原永辉; 戴猷元

    2001-01-01

    Effects of ultrasound on intensification of separation process were investigated through the experiment of desorption equilibrium behavior. Tri-butyl phosphate (TBP) on NKA-Ⅱ resin and phenol on a solvent impregnated resin, CL-TBP resin, were used for desorption processes. The desorption rate was measured with and without ultrasound. Desorption equilibrium was studied under various ultrasonic power densities or thermal infusion. Results showed that the desorption rate with ultrasound was much higher than that with normal thermal infusion. Both ultrasound and thermal infusion broke the desorption equilibrium existed at room temperature. However, after the systems were cooled down, the amount of solute desorbed in the liquid phase in the presence of ultrasound was much higher than that at the temperature corresponding to the same ultrasound power. It is proved that the initial desorption equilibrium was broken as a result of the spot energy effect of ultrasound.``

  6. Mechanical desorption of immobilized proteins using carbon dioxide aerosols for reusable biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Renu; Hong, Seongkyeol [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Jang, Jaesung, E-mail: jjang@unist.ac.kr [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of)

    2015-01-01

    Highlights: • Immobilized proteins were removed using carbon dioxide aerosols. • We observed high removal efficiencies due to the aerosol treatment. • We confirmed the removal with FTIR and X-ray photoelectron spectroscopy. • This CO{sub 2} aerosol treatment did not undermine re-functionalization. • This technique is a fast and damage-free method to reuse a sensor surface. - Abstract: Reusability of a biosensor has recently received considerable attention, and it is closely related with the effective desorption of probe molecules. We present a novel mechanical desorption technique to reuse biosensors by using periodic jets of carbon dioxide (CO{sub 2}) aerosols (a mixture of solid and gaseous CO{sub 2}), and demonstrate its feasibility by removing physically adsorbed and covalently bonded fluorescent proteins i.e., Escherichia coli fluorescein isothiocyanate antibody and bovine serum albumin (E. coli FITC–Ab and FITC–BSA) from silicon chips. The proteins on the chip surfaces were measured by fluorescent images before and after applying the aerosols. The removal efficiency of the aerosol treatment was measured for various concentrations (1–20 μg mL{sup −1}) of E. coli FITC–Ab and FITC–BSA with two different removal cycles (5 and 11 cycles; each cycle: 8 s). We observed high removal efficiencies (>93.5% for physically adsorbed Ab and >84.6% for covalently bonded Ab) at 11 cycle aerosol treatment. This CO{sub 2} aerosol treatment did not undermine re-functionalization, which was confirmed by the fluorescent images of FITC–Abs for fresh and reused chips. Desorption of the immobilized layers was validated by Fourier transform infrared and X-ray photoelectron spectroscopic analyses. We also conducted an experiment on the regeneration of E. coli sensing chips using this aerosol treatment, and the chips were re-used 5 times successfully. This mechanical desorption technique is a highly effective and novel strategy for reusable biosensors.

  7. Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

    OpenAIRE

    Williams, Brent J.; Zhang, Yaping; Zuo, Xiaochen; Martinez, Raul E.; Walker, Michael J.; Kreisberg, Nathan M.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

    2016-01-01

    Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality and, often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analy...

  8. Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

    OpenAIRE

    B. J. Williams; Y. Zhang; X. Zuo; R. E. Martinez; Walker, M. J.; N. M. Kreisberg; Goldstein, A. H.; K. S. Docherty; Jimenez, J.L.

    2015-01-01

    Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality, and often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analy...

  9. Influence of Coal Particle Size on Coal Adsorption and Desorption Characteristics

    Science.gov (United States)

    Zhang, Lei; Aziz, Naj; Ren, Ting; Nemcik, Jan; Tu, Shihao

    2014-10-01

    Accurate testing coal isotherm can play a significant role in the areas of coal seam gas drainage, outburst control, CO2 geo-sequestration, coalbed methane (CBM) and enhanced coalbed methane recovery (ECBM) etc. The effect of particle size on the CO2 and CH4 sorption capacity of bituminous coal from Illawarra, Australia was investigated at 35°C and at pressure up to 4 MPa. A unique indirect gravimetric apparatus was used to measure the gas adsorption and desorption isotherms of coal of different particle sizes ranging from around 150 urn to 16 mm. Langmuir model was used to analysis the experimental results of all gases. Coal particle size was found to have an apparent effect on the coal ash content and helium density results. Coal with larger particle size had higher ash content and higher helium density. The sorption isotherm was found to be highly sensitive with helium density of coal which was determined in the procedure of testing the void volume of sample cell. Hence, coal particle size had a significant influence on the coal sorption characteristics including sorption capacity and desorption hysteresis for CO2 and CH4, especially calculated with dry basis of coal. In this study, the 150-212 um (150 um) coal samples achieved higher sorption capacity and followed by 2.36-3.35 mm (2.4 mm), 8-9.5 mm (8 mm) and 16-19 mm (16 mm) particle size samples. However, the differences between different coal particles were getting smaller when the sorption isotherms are calculated with dry ash free basis. Test with 150 um coal samples were also found to have relatively smaller desorption hysteresis compared with the other larger particle size samples. The different results including adsorption/desorption isotherm, Langmuir parameters and coal hysteresis were all analysed with the CO2 and CH4 gases.

  10. Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

    OpenAIRE

    2014-01-01

    The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can accoun...

  11. Sorption and desorption studies of chromium(VI) from nonviable cyanobacterium Nostoc muscorum biomass

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, V.K. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667 (India)], E-mail: vinodfcy@iitr.ernet.in; Rastogi, A. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2008-06-15

    This communication presents results pertaining to the sorptive and desorptive studies carried out on chromium(VI) removal onto nonviable freshwater cyanobacterium (Nostoc muscorum) biomass. Influence of varying the conditions for removal of chromium(VI), such as the pH of aqueous solution, the dosage of biosorbent, the contact time with the biosorbent, the temperature for the removal of chromium, the effect of light metal ions and the adsorption-desorption studies were investigated. Sorption interaction of chromium on to cyanobacterial species obeyed both the first and the second-order rate equation and the experimental data showed good fit with both the Langmuir and freundlich adsorption isotherm models. The maximum adsorption capacity was 22.92 mg/g at 25 {sup o}C and pH 3.0. The adsorption process was endothermic and the values of thermodynamic parameters of the process were calculated. Various properties of the cyanobacterium, as adsorbent, explored in the characterization part were chemical composition of the adsorbent, surface area calculation by BET method and surface functionality by FTIR. Sorption-desorption of chromium into inorganic solutions and distilled water were observed and this indicated the biosorbent could be regenerated using 0.1 M HNO{sub 3} and EDTA with upto 80% recovery. The biosorbents were reused in five biosorption-desorption cycles without a significant loss in biosorption capacity. Thus, this study demonstrated that the cyanobacterial biomass N. muscorum could be used as an efficient biosorbent for the treatment of chromium(VI) bearing wastewater.

  12. Study on Chemisorption and Desorption of Hydrogen and Nitrogen on Ru-based Ammonia Synthesis Catalyst

    Institute of Scientific and Technical Information of China (English)

    祝一锋; 李小年

    2003-01-01

    The effects of promoters K,Ba,Sm,on the chemisorption and desorption of hydrogen and nitrogen,dispersion of metallic Ru and catalytic activity of active carbon(AC) supported ruthenium catalyst for ammonia synthesis have been studied by means of pulse chromatography,temperature-programmed desorption,and activity test,Promoters K,Ba and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly,and particularly,potassium exhibited the best promotion on the activity because of the strong electronic donation to metallic Ru.Much higher activity can be obtained for Ru/AC catalyst with binary or triple promoters.The activity of Ru/AC catalyst is dependent on the adsorption of hydrogen and nitrogen.The high activity of catalyst could be ascribed to strong dissociation of nitrogen on the catalyst surface.Strong adsorption of hydrogen would inhibit the adsorption of nitrogen,resulted in decrease of the catalytic activity.Ru/AC catalyst promoted by Sm2O3 shows the best dispersion of metallic Ru,since the partly reduced SmO2 on the surface modifies the morphology of active sites and favors the dispersion of metallic Ru.The activity of Ru/AC catalysts is in accordance to the corresponding amount of nitrogen chemisorption and the desorption activation enery of nitrogen.The desorption activation energy for nitrogen decreases in the order of Ru>Ru-Ba>Ru-Sm>Ru-Bs-Sm>Ru-K>Ru-K-Bm>Ru-K-Ba>Ru-K-Ba-Sm,just opposite to the order or catalytic activity,suggesting that the ammonia synthesis over Ru-based catalyst is controlled by the step of dissociation of nitrogen.

  13. Upscaling of U(VI) Desorption and Transport Using Decimeter-Scale Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Derrick

    2015-01-28

    Experimental work was used to validate modeling studies and develop multicontinuum models of U(VI) transport in a contaminated aquifer. At the bench scale, it has been shown that U(VI) desorption is rate-limited and that rates are dependent on the bicarbonate concentration. Two decimeter-scale experiments were conducted in order to help establish rigorous upscaling approaches that could be tested at the tracer test and plume scales.

  14. The role of electron-stimulated desorption in focused electron beam induced deposition

    DEFF Research Database (Denmark)

    van Dorp, Willem F.; Hansen, Thomas Willum; Wagner, Jakob Birkedal;

    2013-01-01

    rate is lower at higher substrate temperatures. From Arrhenius plots we calculated the activation energy for desorption, Edes, of W(CO)6. We found an average value for Edes of 20.3 kJ or 0.21 eV, which is 2.5–3.0 times lower than literature values. This difference between estimates for Edes from FEBIP...

  15. The Sorption/Desorption Behavior of Uranium in Transport Studies Using Yucca Mountain Alluvium

    Energy Technology Data Exchange (ETDEWEB)

    Scism, Cynthia D. [Univ. of New Mexico, Albuquerque, NM (United States)

    2005-12-01

    Yucca Mountain, Nevada is the proposed site of a geologic repository for the disposal of spent nuclear fuel and high-level radioactive waste in the United States. In the event repository engineered barriers fail, the saturated alluvium located south of Yucca Mountain is expected to serve as a natural barrier to the migration of radionuclides to the accessible environment. The purpose of this study is to improve the characterization of uranium retardation in the saturated zone at Yucca Mountain to support refinement of an assessment model. The distribution of uranium desorption rates from alluvium obtained from Nye County bore holes EWDP-19IM1, EWDP-10SA, EWDP-22SA were studied to address inconsistencies between results from batch sorption and column transport experiments. The alluvium and groundwater were characterized to better understand the underlying mechanisms of the observed behavior. Desorption rate constants were obtained using an activity based mass balance equation and column desorption experiments were analyzed using a mathematical model utilizing multiple sorption sites with different first-order forward and reverse reaction rates. The uranium desorption rate constants decreased over time, suggesting that the alluvium has multiple types of active sorption sites with different affinities for uranium. While a significant fraction of the initially sorbed uranium desorbed from the alluvium quite rapidly, a roughly equivalent amount remained sorbed after several months of testing. The information obtained through this research suggests that uranium may experience greater effective retardation in the alluvium than simple batch sorption experiments would suggest. Electron Probe Microanalysis shows that uranium is associated with both clay minerals and iron oxides after sorption to alluvial material. These results provide further evidence that the alluvium contains multiple sorption sites for uranium.

  16. Effects of organic acids on Cd adsorption and desorption by two anthropic soils

    Institute of Scientific and Technical Information of China (English)

    Jingui WANG; Jialong LV; Yaolong FU

    2013-01-01

    The objective of this experiment was to study the effects of malic, tartaric, oxalic, and citric acid on the adsorption and desorption characteristics of Cd by two typical anthropic soils (lou soil and irrigation-silted soil) in North-west China. Cadmium adsorption and desorption were studied under a range of temperatures (25℃, 30℃, 35℃, 40℃), organic acid concentrations (0.5-5.0 mmol·L-1), and pH values (2-8). The results showed that the Cd adsorption capacity of the lou soil was significantly greater than that of the irrigation-silted soil. Generally, Cd adsorption increased as the temperature increased. In the presence of NaNO3, the adsorption of Cd was endothermic with △H values of 31.365 kJ·mo1-1 for lou soil and 28.278 kJ·mol-1 for irrigation-silted soil. The endothermic reaction indicated that H bonds were the main driving force for Cd adsorption in both soils. However, different concentrations of organic acids showed various influences on the two soils. In the presence of citric acid, chemical adsorption and van der Waals interactions were the main driving forces for Cd adsorption rather than H bonds. Although the types of organic acids and soil properties were different, the effects of the organic acids on the adsorption and desorption of Cd were similar in the two soils. The adsorption percentage of Cd generally decreased as organic acid concentrations increased. In contrast, the adsorption percentage increased as the pH of the initial solution increased. The exception was that adsorption percentage of Cd increased slightly as oxalic acid concentrations increased. In contrast, the desorption percentage of Cd increased with increasing concentrations of organic acids but decreased as the initial solution pH increased.

  17. Current distribution in ESD (Electron Stimulated Desorption) diodes. Cross section corrections

    Science.gov (United States)

    Lin, J. C.; Gomer, R.

    1985-11-01

    The electron current distribution in diodes consisting of a rectangular crystal and an electron emitting filament parallel to and in front of it, used in several electron stimulated desorption (ESD) experiments has been determined by means of a dummy crystal constructed from uniformly transparent Lektromesh and a moveable, suitably constructed fine probe. It was found that for straight filaments the distribution was uniform along the narrow, but nearly triangular along the long dimension of the crystal.

  18. Remote mass spectrometric sampling of electrospray- and desorption electrospray-generated ions using an air ejector.

    Science.gov (United States)

    Dixon, R Brent; Bereman, Michael S; Muddiman, David C; Hawkridge, Adam M

    2007-10-01

    A commercial air ejector was coupled to an electrospray ionization linear ion trap mass spectrometer (LTQ) to transport remotely generated ions from both electrospray (ESI) and desorption electrospray ionization (DESI) sources. We demonstrate the remote analysis of a series of analyte ions that range from small molecules and polymers to polypeptides using the AE-LTQ interface. The details of the ESI-AE-LTQ and DESI-AE-LTQ experimental configurations are described and preliminary mass spectrometric data are presented.

  19. Upscaling of U(VI) Desorption and Transport Using Decimeter-Scale Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Derrick [Colorado School of Mines, Golden, CO (United States)

    2014-12-22

    Experimental work was used to validate modeling studies and develop multicontinuum models of U(VI) transport in a contaminated aquifer. At the bench scale, it has been shown that U(VI) desorption is rate-limited and that rates are dependent on the bicarbonate concentration. Two decimeter-scale experiments were conducted in order to help establish rigorous upscaling approaches that could be tested at the tracer test and plume scales.

  20. Desorption of cadmium from a natural Shanghai clay using citric acid industrial wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Gu Yingying, E-mail: guyong99hg@yahoo.com.cn [Department of Environmental Science and Engineering, College of Chemistry and Chemical Engineering, China University of Petroleum (East China), 66 West Changjiang Road, Qingdao 266555 (China); Yeung, Albert T., E-mail: yeungat@hku.hk [Department of Civil Engineering, The University of Hong Kong, Pokfulam Road (Hong Kong)

    2011-07-15

    Highlights: {yields} CAIW is very effective in desorbing cadmium from soil particle surfaces at soil mixture pHs of lower than 5. {yields} The cadmium desorption efficiency of CAIW also depends on the initial sorbed concentration of cadmium on soil particle surfaces. {yields} Complexions of cadmium with citric acid and acetic acid are the dominant mechanisms for cadmium desorption in the soil mixture pH range of 4-8. {yields} CAIW may be a promising enhancement agent for the remediation of heavy metal-contaminated soils. - Abstract: The sorption/desorption characteristics of heavy metals onto/from soil particle surfaces are the primary factors controlling the success of the remediation of heavy-metal contaminated soils. These characteristics are pH-dependent, chemical-specific, and reversible; and can be modified by enhancement agents such as chelates and surfactants. In this study, batch experiments were conducted to evaluate the feasibility of using citric acid industrial wastewater (CAIW) to desorb cadmium from a natural clay from Shanghai, China at different soil mixture pHs. It can be observed from the results that the proportion of cadmium desorbed from the soil using synthesized CAIW is generally satisfactory, i.e., >60%, when the soil mixture pH is lower than 6. However, the proportion of desorbed cadmium decreases significantly with increase in soil mixture pH. The dominant cadmium desorption mechanism using CAIW is the complexion of cadmium with citric acid and acetic acid in CAIW. It is concluded that CAIW can be a promising enhancement agent for the remediation of cadmium-contaminated natural soils when the environmental conditions are favorable. As a result, CAIW, a waste product itself, can be put into productive use in soil remediation.

  1. Unusual Fragmentation of Peptide and Protein in Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    Mitsuo Takayama

    2001-01-01

    Unusual amine - bond fragmentation on the peptide/protein backbone has been reported using matrix - assisted laser desorption/ionization time - of- flight mass spectrometry (MALDI - TOFMS)The amine - bond cleavage occurred without metastable decay, while the peptide - bond cleavage occurred with metastable decay of peptide ions in a drift region of TOF mass analyzer. It was presumed that the amine - bond cleavage occurred as a non - ergodic process independent of the ionization under MALDI conditions.

  2. Baking and helium glow discharge cleaning of SST-1 Tokamak with graphite plasma facing components

    Science.gov (United States)

    Semwal, P.; Khan, Z.; Raval, D. C.; Dhanani, K. R.; George, S.; Paravastu, Y.; Prakash, A.; Thankey, P.; Ramesh, G.; Khan, M. S.; Saikia, P.; Pradhan, S.

    2017-04-01

    Graphite plasma facing components (PFCs) were installed inside the SST-1 vacuum vessel. Prior to installation, all the graphite tiles were baked at 1000 °C in a vacuum furnace operated below 1.0 × 10-5 mbar. However due to the porous structure of graphite, they absorb a significant amount of water vapour from air during the installation process. Rapid desorption of this water vapour requires high temperature bake-out of the PFCs at ≥ 250 °C. In SST-1 the PFCs were baked at 250 °C using hot nitrogen gas facility to remove the absorbed water vapour. Also device with large graphite surface area has the disadvantage that a large quantity of hydrogen gets trapped inside it during plasma discharges which makes density control difficult. Helium glow discharge cleaning (He-GDC) effectively removes this stored hydrogen as well as other impurities like oxygen and hydrocarbon within few nano-meters from the surface by particle induced desorption. Before plasma operation in SST-1 tokamak, both baking of PFCs and He-GDC were carried out so that these impurities were removed effectively. The mean desorption yield of hydrogen was found to be 0.24. In this paper the results of baking and He-GDC experiments of SST-1 will be presented in detail.

  3. Processes of adsorption/desorption of iodides and cadmium cations onto/from Ag(111

    Directory of Open Access Journals (Sweden)

    VLADIMIR D. JOVIĆ

    2011-02-01

    Full Text Available In this work, the adsorption/desorption processes of iodides and cadmium cations in the presence of iodides onto/from Ag(111 were investigated. It was shown that both processes were complex, characterized by several peaks on the cyclic voltammograms (CVs. By PeakFit analysis of the recorded CVs and subsequent fitting of the obtained peaks by the Frumkin adsorption isotherm, the interaction parameter (f and the Gibbs energy of adsorption (DGads for each adsorbed phase were determined. In the case of iodide adsorption, four peaks were characterized by negative values of f, indicating attractive lateral interaction between the adsorbed anions, while two of them possessed value of f < –4, indicating phase transition processes. The adsorption/desorption processes of cadmium cations (underpotential deposition – UPD of cadmium in the presence of iodide anions was characterized by two main peaks, each of them being composed of two or three peaks with negative values of f. By the analysis of charge vs. potential dependences obtained either from the CVs or current transients on potentiostatic pulses, it was concluded that adsorbed iodides did not undergo desorption during the process of Cd UPD, but became replaced by Cd ad-atoms and remained adsorbed on top of a Cd layer and/or in between Cd the ad-atoms.

  4. Desorption of water from hydrophilic MCM-41 mesopores: positron annihilation, FTIR and MD simulation studies

    Science.gov (United States)

    Maheshwari, Priya; Dutta, D.; Muthulakshmi, T.; Chakraborty, B.; Raje, N.; Pujari, P. K.

    2017-02-01

    The desorption mechanism of water from the hydrophilic mesopores of MCM-41 was studied using positron annihilation lifetime spectroscopy (PALS) and attenuated total reflection Fourier transform infrared spectroscopy supplemented with molecular dynamics (MD) simulation. PALS results indicated that water molecules do not undergo sequential evaporation in a simple layer-by-layer manner during desorption from MCM-41 mesopores. The results suggested that the water column inside the uniform cylindrical mesopore become stretched during desorption and induces cavitation (as seen in the case of ink-bottle type pores) inside it, keeping a dense water layer at the hydrophilic pore wall, as well as a water plug at both the open ends of the cylindrical pore, until the water was reduced to a certain volume fraction where the pore catastrophically empties. Before being emptied, the water molecules formed clusters inside the mesopores. The formation of molecular clusters below a certain level of hydration was corroborated by the MD simulation study. The results are discussed.

  5. Forced Desorption of Bovine Serum Albumin and Lysozyme from Graphite: Insights from Molecular Dynamics Simulation.

    Science.gov (United States)

    Mücksch, Christian; Urbassek, Herbert M

    2016-08-18

    We use molecular dynamics (MD) simulation to study the adsorption and desorption of two widely different proteins, bovine serum albumin (BSA) and lysozyme, on a graphite surface. The adsorption is modeled using accelerated MD to allow the proteins to find optimum conformations on the surface. Our results demonstrate that the "hard protein" lysozyme retains much of its secondary structure during adsorption, whereas BSA loses it almost completely. BSA has a considerably larger adsorption energy compared to that of lysozyme, which does not scale with chain length. Desorption simulations are carried out using classical steered MD. The BSA molecule becomes fully unzipped during pull-off, whereas several helices survive this process in lysozyme. The unzipping process shows up in the force-distance curve of BSA as a series of peaks, whereas only a single or few, depending on protein orientation, force peaks occur for lysozyme. The maximum desorption force is larger for BSA than for lysozyme, but only by a factor of about 2.3.

  6. Changes of structural and hydrogen desorption properties of MgH2 indused by ion irradiation

    Directory of Open Access Journals (Sweden)

    Kurko Sandra V.

    2010-01-01

    Full Text Available Changes in structural and hydrogen desorption properties of MgH2 induced by ion irradiation have been investigated. MgH2 powder samples have been irradiated with 45 keV B3+ and 120 keV Ar8+ions, with ion fluence of 1015 ions/cm2. The effects of ion irradiation are estimated by numerical calculations using SRIM package. The induced material modifications and their consequences on hydrogen dynamics in the system are investigated by XRD, particle size distribution and TPD techniques. Changes of TPD spectra with irradiation conditions suggest that there are several mechanisms involved in desorption process which depend on defect concentration and their interaction and ordering. The results confirmed that the near-surface area of MgH2 and formation of a substoichiometric MgHx (x<2 play a crucial role in hydrogen kinetics and that various concentrations of induced defects substantially influence H diffusion and desorption kinetics in MgH2. The results also confirm that there is possibility to control the thermodynamic parameters by controlling vacancies concentration in the system.

  7. Brominated Tyrosine and Polyelectrolyte Multilayer Analysis by Laser Desorption VUV Postionization and Secondary Ion Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    University of Illinois at Chicago; Blaze, Melvin M. T.; Takahashi, Lynelle; Zhou, Jia; Ahmed, Musahid; Gasper, Gerald; Pleticha, F. Douglas; Hanley, Luke

    2011-03-14

    The small molecular analyte 3,5-dibromotyrosine (Br2Y) and chitosan-alginate polyelectrolyte multilayers (PEM) with and without adsorbed Br2Y were analyzed by laser desorption postionization mass spectrometry (LDPI-MS). LDPI-MS using 7.87 eV laser and tunable 8 ? 12.5 eV synchrotron vacuum ultraviolet (VUV) radiation found that desorption of clusters from Br2Y films allowed detection by≤8 eV single photon ionization. Thermal desorption and electronic structure calculations determined the ionization energy of Br2Y to be ~;;8.3?0.1 eV and further indicated that the lower ionization energies of clusters permitted their detection at≤8 eV photon energies. However, single photon ionization could only detect Br2Y adsorbed within PEMs when using either higher photon energies or matrix addition to the sample. All samples were also analyzed by 25 keV Bi3 + secondary ion mass spectrometry (SIMS), with the negative ion spectra showing strong parent ion signal which complemented that observed by LDPI-MS. The negative ion SIMS depended strongly on the high electron affinity of this specific analyte and the analyte?s condensed phase environment.

  8. Layer resolved spectroscopy of potassium adsorbed on a Ru(001) surface: Photoemission and thermal desorption study

    Energy Technology Data Exchange (ETDEWEB)

    Hrbek, J. (Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (US)); Shek, M. (Department of Physics, Hunter College of CUNY, New York, New York 10021); Sham, T.K. (Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7, Canada); Xu, G. (Chemistry Department, Brookhaven National Laboratory, Upton, New York, 11973)

    1989-11-01

    High-resolution photoemission spectroscopy and thermal desorption were used to study the coverage dependence of the K 3{ital p}{sub 3/2,1/2} core levels of K overlayers on Ru(001). Three doublets were observed to evolve sequentially and to shift to higher binding energy with increasing coverage of potassium. The doublets were assigned to photoemission from the interface (first layer), bulk'' (second layer), and surface (third layer). Spin--orbit splitting was observed for the first time in the condensed potassium phase by photoemission. The results are discussed in terms of the equivalent core approximation using a Born--Haber cycle. In the thermal desorption data three coverage regimes can be distinguished: a first layer desorbing with first-order kinetics and a strongly decreasing heat of adsorption ({ital E}{sub {ital A}} =2.80--0.87 eV); a second layer with zero-order desorption kinetics and {ital E}{sub {ital A}} =0.78 eV; a third layer and multilayers with the same kinetic order but with {ital E}{sub {ital A}} increasing from 0.78 to 0.93 eV, which is close to the heat of sublimation of potassium.

  9. Evidence for a CO Desorption Front in the Outer AS 209 Disk

    Science.gov (United States)

    Huang, Jane; Öberg, Karin I.; Andrews, Sean M.

    2016-05-01

    Millimeter observations of CO isotopologues are often used to make inferences about protoplanetary disk gas density and temperature structures. The accuracy of these estimates depends on our understanding of CO freezeout and desorption from dust grains. Most models of these processes indicate that CO column density decreases monotonically with distance from the central star due to a decrease in gas density and freezeout beyond the CO snowline. We present ALMA Cycle 2 observations of 12CO, 13CO, and C18O J=2-1 emission that instead suggest CO enhancement in the outer disk of T Tauri star AS 209. Most notably, the C18O emission consists of a central peak and a ring at a radius of ˜ 1\\prime \\prime (120 au), well outside the expected CO snowline. We propose that the ring arises from the onset of CO desorption near the edge of the millimeter dust disk. CO desorption exterior to a CO snowline may occur via non-thermal processes involving cosmic rays or high-energy photons, or via a radial thermal inversion arising from dust migration.

  10. Evidence for a CO desorption front in the outer AS 209 disk

    CERN Document Server

    Huang, Jane; Andrews, Sean M

    2016-01-01

    Millimeter observations of CO isotopologues are often used to make inferences about protoplanetary disk gas density and temperature structures. The accuracy of these estimates depends on our understanding of CO freezeout and desorption from dust grains. Most models of these processes indicate that CO column density decreases monotonically with distance from the central star due to a decrease in gas density and freezeout beyond the CO snowline. We present ALMA Cycle 2 observations of $^{12}$CO, $^{13}$CO, and C$^{18}$O $J=2-1$ emission that instead suggest CO enhancement in the outer disk of T Tauri star AS 209. Most notably, the C$^{18}$O emission consists of a central peak and a ring at a radius of $\\sim1''$ (120 AU), well outside the expected CO snowline. We propose that the ring arises from the onset of CO desorption near the edge of the millimeter dust disk. CO desorption exterior to a CO snowline may occur via non-thermal processes involving cosmic rays or high-energy photons, or via a radial thermal inv...

  11. Effect of dissolved organic matter on adsorption and desorption of mercury by soils

    Institute of Scientific and Technical Information of China (English)

    YANG Yongkui; LIANG Li; WANG Dingyong

    2008-01-01

    Effects of dissolved organic matter (DOM) on adsorption and desorption of Hg were investigated in two kinds of soils, Xanthi-Udic Ferralosols (XUF) and Typic Purpli-Udic Cambosols (TPUC). The DOM was obtained from humus soil (DOMH), rice straw (DOMR), and pig manure (DOMP). The presence of DOM obviously reduced Hg maximum adsorption capacity with up to 40% decreases over the control, being an order of DOMH (250.00 mg/kg) (270.27 mg/kg) (312.50 mg/kg) desorption from the soils. The kinetic models, the Two-constant equation and Elovich equation, were applicable to describe the adsorption and desorption processes of Fig in soils. The speed of Hg adsorption was consistently slowed down by the existence of DOM..

  12. Desorption and Degradation of Organic Contaminants in Soil by Microwave Radiation

    Science.gov (United States)

    Jeong, S.; Kim, H.

    2011-12-01

    Many military bases located in the down towns of South Korea are asked to move outside of the urban areas due to the growth of the cities. During the past 60 years, many military bases of South Korea have been operated and according to that, parts of the soil have been polluted with organic contaminants such as total petroleum hydrocarbons (TPH), solvents, etc. In the case of South Korea, rapid remediation of the contaminated soil is required for efficient development of land. Thermal desorption is one of the most efficient and rapid remediation methods for polluted soil to clean up, but the fact is it consumes a lot of energy. In this study, desorption and degradation of organic contaminants in soil using microwave radiation is investigated in order to energy efficient and rapid remediation technique development. Polluted soil collected from a military base was remediated in the laboratory using a home made microwave reactor. In order to study uncontaminated soil was also intentionally contaminated with diesel, TCE, and phenanthrene, respectively, for a month and used for experiments. Contaminated soil places within stainless steel reactor and microwave radiates with nitrogen gas. Emitted gas from the reactor was collected with methanol or acetonitrile solution every 3 minute for 15 minutes, and analyzed with GC, HPLC, GC/MS, respectively. The TPH contaminated soil from military base desorbed initially light hydrocarbon (retention time reaction, iron powder, graphite will be added to the contaminated soil and desorption and degradation properties of this soil during microwave radiation will be studied.

  13. SORPTION AND DESORPTION CHARACTERISTICS OF CADMIUM BY FOUR DIFFERENT SOILS IN NORTHEAST CHINA

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; SONG Feng-bin

    2005-01-01

    Four soils, phaeozem (PM), saline-alkali soil (SA), meadow albic bleached soil (MA) and dark brown forest soil (DB) from Northeast China were used to examine the sorption and desorption characteristics of Cd and pH influence on it. According to sorption experiment without pH control, the order of amount of absorbed Cd by soils was:SA>PM>DB>MA. The results from non-linear fitting method showed that Langmuir and Freundrich models were more adaptable than Temkin model in describing the sorption data. The maximum sorption amounts from Langmuir model were: PM>SA>MA>DB. Exponential equation for PM and SA and quadratic equation for MA and DB were suitable to fit the desorption data. The order of average desorption percentage was: MA>DB>PM>SA. The amounts of sorption by PM, DB and MA reached the maximum in pH 9.0, while sorption by SA was linearly increased in the experimental range of pH 3.3-11.4. In uniform pH, however, Cd sorption by SA was the minimum among four soils, which indicated that the more amounts of Cd absorbed by SA in isotherm sorption were ascribed to the higher soil pH. The higher sorption of Cd in PM resulted from the higher percentage of organic matter and clay components.

  14. Desorption and mobilization of three strobilurin fungicides in three types of soil.

    Science.gov (United States)

    Wu, Ping; Wu, Wen Zhu; Han, Zhi Hua; Yang, Hong

    2016-06-01

    Phenamacril (JS399-19 with independent intellectual property developed by China), azoxystrobin, and kresoxim-methyl are strobilurin fungicide. Due to their broad spectrum and good control of most of known fungi, strobilurin fungicide has been widely used in agriculture management. Thus, it is important to evaluate their environmental behaviors particularly in soils and underground water. In this study, the sorption/desorption and mobility of strobilurin fungicides in three Chinese soils (Jiangxi red soil, Taihu paddy soil, and Northeast China black soil) were conducted using comprehensively analytic approaches including batch experiment and soil thin-layer chromatography. The strobilurin fungicides were hard to be adsorbed in Jiangxi red soil but had medium adsorption capability in Tanhu paddy soil and Northeast China black soil, while the desorption of three strobilurin fungicides ranked in the order of Jiangxi red soil > Taihu paddy soil > Northeast China black soil. Soil properties including soil organic matter (SOM), pH, and cationic exchange capacity (CEC) affected the adsorption/desorption of the fungicides. Azoxystrobin and kresoxim-methyl had weak mobility in the soils. JS399-19 was moderately mobile in Jiangxi red soil but was not easily moved in Taihu paddy soil and Northeast China black soil. Due to their weak mobility in soils, these strobilurin fungicides tended to remain in the soil phase but not to shift downward to underground water. As azoxystrobin and JS399-19 had a long retention period in soil, there may become persistent residues in the soil environment.

  15. Sinapine detection in radish taproot using surface desorption atmospheric pressure chemical ionization mass spectrometry.

    Science.gov (United States)

    Huang, Dejuan; Luo, Liping; Jiang, Cuicui; Han, Jing; Wang, Jiang; Zhang, Tingting; Jiang, Jie; Zhou, Zhiquan; Chen, Huanwen

    2011-03-23

    Plant research and natural product detection are of sustainable interests. Benefited by direct detection with no sample preparation, sinapine, a bioactive chemical usually found in various seeds of Brassica plants, has been unambiguously detected in radish taproot (Raphanus sativus) tissue using a liquid-assisted surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS). A methanol aqueous solution (1:1) was nebulized by a nitrogen sheath gas toward the corona discharge, resulting in charged ambient small droplets, which affected the radish tissue for desorption/ionization of analytes on the tissue surface. Thus, sinapine was directly detected and identified by tandem DAPCI-MS experiments without sample pretreatment. The typical relative standard deviation (RSD) of this method for sinapine detection was 5-8% for six measurements (S/N=3). The dynamic response range was 10(-12)-10(-7) g/cm2 for sinapine on the radish skin surface. The discovery of sinapine in radish taproot was validated by using HPLC-UV methods. The data demonstrated that DAPCI assisted by solvent enhanced the overall efficiency of the desorption/ionization process, enabling sensitive detection of bioactive compounds in plant tissue.

  16. Precursor ion scan profiles of acylcarnitines by atmospheric pressure thermal desorption chemical ionization tandem mass spectrometry.

    Science.gov (United States)

    Paglia, Giuseppe; D'Apolito, Oceania; Corso, Gaetano

    2008-12-01

    The fatty acyl esters of L-carnitine (acylcarnitines) are useful biomarkers for the diagnosis of some inborn errors of metabolism analyzed by liquid chromatography/tandem mass spectrometry. In this study the acylcarnitines were analyzed by atmospheric pressure thermal desorption chemical ionization using a commercial tandem mass spectrometer (APTDCI-MS/MS). The method is based on the precursor ion scan mode determination of underivatized acylcarnitines desorbed from samples by a hot desolvation gas flow and ionized by a corona pin discharge. During desorption/ionization step the temperature induces the degradation of acylcarnitines; nevertheless, the common fragment to all acylcarnitines [MH-59](+) is useful for analyzing their profile. APTDCI parameters, including angle of collection and incidence, gas flows and temperatures, were optimized for acylcarnitines. The experiments were performed drying 2 microL of an equimolar mixture of acylcarnitine standards on a glass slide. The specificity was evaluated by comparing product ion spectra and the precursor ion spectra of 85 m/z of acylcarnitines obtained by the APTDCI method and by electrospray ionization flow injection analysis (ESI-FIA). The method was also employed to analyze acylcarnitines extracted from a pathological dried blood spot and a control. The method enables analysis of biological samples and recognition of some acylcarnitines that are diagnostic markers of inherited metabolic diseases. The intrinsic high-throughput analysis of the ambient desorption ionization methods offers a new opportunity either for its potential application in clinical chemistry and for the expanded screening of some inborn errors of metabolism.

  17. PCDD/F formation during thermal desorption of p,p'-DDT contaminated soil.

    Science.gov (United States)

    Zhao, Zhonghua; Ni, Mingjiang; Li, Xiaodong; Buekens, Alfons; Yan, Jianhua

    2017-05-01

    Thermal treatment of polychlorinated biphenyls (PCB) contaminated soil was shown in earlier work to generate polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). In this study, the PCDD/F were studied arising during the remediation of p,p'-DDT contaminated soil by thermal desorption. Three kinds of soil (sandy, clayey and lateritic soil) were tested to investigate the effect of soil texture on PCDD/F formation. Those soils were artificially polluted with p,p'-DDT, obtaining a concentration level of 100 mg/kg. Thermal desorption experiments were conducted for 10 min at 300 °C in an air atmosphere. The total concentration of PCDD/F generated for three soils were 331, 803 and 865 ng/kg, respectively, and TeCDD and TeCDF were dominant among all PCDD/F congeners. After thermal desorption, the total amount of PCDD/F generated both in soil and in off-gas correlated positively with the amount of DDT added to soil. In addition, a possible pathway of the formation of PCDD/F was presented.

  18. Molecular mechanism of adsorption/desorption hysteresis: dynamics of shale gas in nanopores

    Science.gov (United States)

    Chen, Jie; Wang, FengChao; Liu, He; Wu, HengAn

    2017-01-01

    Understanding the adsorption and desorption behavior of methane has received considerable attention since it is one of the crucial aspects of the exploitation of shale gas. Unexpectedly, obvious hysteresis is observed from the ideally reversible physical sorption of methane in some experiments. However, the underlying mechanism still remains an open problem. In this study, Monte Carlo (MC) and molecular dynamics (MD) simulations are carried out to explore the molecular mechanisms of adsorption/desorption hysteresis. First, a detailed analysis about the capillary condensation of methane in micropores is presented. The influence of pore width, surface strength, and temperature on the hysteresis loop is further investigated. It is found that a disappearance of hysteresis occurs above a temperature threshold. Combined with the phase diagram of methane, we explicitly point out that capillary condensation is inapplicable for the hysteresis of shale gas under normal temperature conditions. Second, a new mechanism, variation of pore throat size, is proposed and studied. For methane to pass through the throat, a certain energy is required due to the repulsive interaction. The required energy increases with shrinkage of the throat, such that the originally adsorbed methane cannot escape through the narrowed throat. These trapped methane molecules account for the hysteresis. Furthermore, the hysteresis loop is found to increase with the increasing pressure and decreasing temperature. We suggest that the variation of pore throat size can explain the adsorption/desorption hysteresis of shale gas. Our conclusions and findings are of great significance for guiding the efficient exploitation of shale gas.

  19. Ultraviolet photoelectron spectroscopy and electron stimulated desorption from CaF sub 2

    CERN Document Server

    Huisinga, M

    1999-01-01

    resulted in a positively charged sample surface, thus giving an undetermined electrostatic contribution to the F+ desorption energies. In this thesis, a method was developed allowing for the first time to measure a positive surface potential of an insulator under electron irradiation. Thus, the kinetic energy of F+ ions desorbing from CaF sub 2 crystals could be corrected for surface charge to determine the energy characteristic for the desorption process. The corrected peak of the F+ kinetic energy distribution was at about 0.9 eV for crystals cleaved in UHV. It was shown that coverage of the surface with oxygen or fluorine results in a high positive potential, while metallization causes a low surface potential. In particular, the surface potential of crystals cleaved in UHV shows a pronounced minimum after about 10 to 20 min of electron irradiation. This effect could be explained by a balance of F sup + desorption and diffusion of fluorine from the bulk. Calcium difluoride crystals were investigated with ul...

  20. Zinc adsorption and desorption characteristics in root cell wall involving zinc hyperaccumulation in Sedum alfredii Hance.

    Science.gov (United States)

    Li, Ting-qiang; Yang, Xiao-e; Meng, Fan-hua; Lu, Ling-li

    2007-02-01

    Radiotracer techniques were employed to characterize (65)Zn adsorption and desorption in root-cell-wall of hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) species of Sedum alfredii Hance. The results indicated that at the end of a 30 min short time radioisotope loading period, comparable amounts of (65)Zn were accumulated in the roots of the two ecotypes Sedum alfredii, whereas 2.1-fold more (65)Zn remains in NHE root after 45-min desorption. At the end of 60 min uptake period, no difference of (65)Zn accumulation was observed in undesorbed root-cell-wall of Sedum alfredii. However, 3.0-fold more (65)Zn accumulated in desorbed root-cell-wall of NHE. Zn(2+) binding in root-cell-wall preparations of NHE was greater than that in HE under high Zn(2+) concentration. All these results suggested that root-cell-wall of the two ecotypes Sedum alfredii had the same ability to adsorb Zn(2+), whereas the desorption characteristics were different, and with most of (65)Zn binding on root of HE being available for loading into the xylem, as a result, more (65)Zn was translocated to the shoot.

  1. Using chemical desorption of PAHs from sediment to model biodegradation during bioavailability assessment.

    Science.gov (United States)

    Spasojević, Jelena M; Maletić, Snežana P; Rončević, Srđan D; Radnović, Dragan V; Cučak, Dragana I; Tričković, Jelena S; Dalmacija, Božo D

    2015-01-01

    This work compares the biodegradation potential of four polycyclic aromatic hydrocarbons (PAH) (phenanthrene, pyrene, chrysene and benzo(a)pyrene, chosen as representatives of the 3, 4 and 5 ring PAHs) with their desorption from sediment by XAD4 resin and methyl-β-cyclodextrin (MCD). The biodegradation study was conducted under various conditions (biostimulation, bioaugmentation and their combination). The results show that total PAH removal in all treatments except biostimulation gave similar results, whereby the total amount of PAHs was decreased by about 30-35%. The desorption experiment showed that XAD4 desorbed a greater fraction of phenanthrene (77% versus 52%), and benzo(a)pyrene (44% versus 25%) than MCD. The results for four ring PAHs were similar for both desorption agents (about 30%). Comparing the maximum biodegraded amount of each PAH with the rapidly desorbed XAD4 and MCD fraction, XAD4 was found to correlate better with biodegradation for the high molecular PAHs (pyrene, chrysene, benzo(a)pyrene), although it overestimated the availability of phenanthrene. In contrast, MCD showed better correlation with the biodegradation of low molecular weight PAHs.

  2. Laser Desorption Ionization Mass Spectrometry Imaging of Drosophila Brain Using Matrix Sublimation versus Modification with Nanoparticles.

    Science.gov (United States)

    Phan, Nhu T N; Mohammadi, Amir Saeid; Dowlatshahi Pour, Masoumeh; Ewing, Andrew G

    2016-02-02

    Laser desorption ionization mass spectrometry (LDI-MS) is used to image brain lipids in the fruit fly, Drosophila, a common invertebrate model organism in biological and neurological studies. Three different sample preparation methods, including sublimation with two common organic matrixes for matrix-assisted laser desorption ionization (MALDI) and surface-assisted laser desorption ionization (SALDI) using gold nanoparticles, are examined for sample profiling and imaging the fly brain. Recrystallization with trifluoroacetic acid following matrix deposition in MALDI is shown to increase the incorporation of biomolecules with one matrix, resulting in more efficient ionization, but not for the other matrix. The key finding here is that the mass fragments observed for the fly brain slices with different surface modifications are significantly different. Thus, these approaches can be combined to provide complementary analysis of chemical composition, particularly for the small metabolites, diacylglycerides, phosphatidylcholines, and triacylglycerides, in the fly brain. Furthermore, imaging appears to be beneficial using modification with gold nanoparticles in place of matrix in this application showing its potential for cellular and subcellular imaging. The imaging protocol developed here with both MALDI and SALDI provides the best and most diverse lipid chemical images of the fly brain to date with LDI.

  3. Enhanced desorption of persistent organic pollutants from microplastics under simulated physiological conditions.

    Science.gov (United States)

    Bakir, Adil; Rowland, Steven J; Thompson, Richard C

    2014-02-01

    Microplastics have the potential to uptake and release persistent organic pollutants (POPs); however, subsequent transfer to marine organisms is poorly understood. Some models estimating transfer of sorbed contaminants to organisms neglect the role of gut surfactants under differing physiological conditions in the gut (varying pH and temperature), examined here. We investigated the potential for polyvinylchloride (PVC) and polyethylene (PE) to sorb and desorb (14)C-DDT, (14)C-phenanthrene (Phe), (14)C-perfluorooctanoic acid (PFOA) and (14)C-di-2-ethylhexyl phthalate (DEHP). Desorption rates of POPs were quantified in seawater and under simulated gut conditions. Influence of pH and temperature was examined in order to represent cold and warm blooded organisms. Desorption rates were faster with gut surfactant, with a further substantial increase under conditions simulating warm blooded organisms. Desorption under gut conditions could be up to 30 times greater than in seawater alone. Of the POP/plastic combinations examined Phe with PE gave the highest potential for transport to organisms.

  4. Application of thermal desorption for the identification of mercury species in solids derived from coal utilization.

    Science.gov (United States)

    Rumayor, M; Diaz-Somoano, M; Lopez-Anton, M A; Martinez-Tarazona, M R

    2015-01-01

    The speciation of mercury is currently attracting widespread interest because the emission, transport, deposition and behaviour of toxic mercury species depend on its chemical form. The identification of these species in low concentrations is no easy task and it is even more complex in coal combustion products due to the fact that these products contain organic and mineral matter that give rise to broad peaks and make it difficult to carry out qualitative and quantitative analysis. In this work, a solution to this problem is proposed using a method based on thermal desorption. A sequential extraction procedure was employed for the comparison and validation of the method developed. Samples of fly ashes and soils were analyzed by both of these methods, and thermal desorption was found to be an appropriate technique for mercury speciation. Even in the case of low mercury contents, recovery percentages were close to 100%. The main mercury species identified in the samples studied were HgS and, to a lesser extent, HgO and HgSO4. In addition, although the presence of mercury complexes cannot be demonstrated, the desorption behaviour and sequential extraction results suggest that this element might be associated with the mineral matrix or with carbon particles in some of the solids. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Non-thermal desorption from interstellar dust grains via exothermic surface reactions

    CERN Document Server

    Garrod, R T; Herbst, E

    2007-01-01

    Aims: The gas-phase abundance of methanol in dark quiescent cores in the interstellar medium cannot be explained by gas-phase chemistry. In fact, the only possible synthesis of this species appears to be production on the surfaces of dust grains followed by desorption into the gas. Yet, evaporation is inefficient for heavy molecules such as methanol at the typical temperature of 10 K. It is necessary then to consider non-thermal mechanisms for desorption. But, if such mechanisms are considered for the production of methanol, they must be considered for all surface species. Methods: Our gas-grain network of reactions has been altered by the inclusion of a non-thermal desorption mechanism in which the exothermicity of surface addition reactions is utilized to break the bond between the product species and the surface. Our estimated rate for this process derives from a simple version of classical unimolecular rate theory with a variable parameter only loosely contrained by theoretical work. Results: Our results ...

  6. Biodegradation of persistent organics can overcome adsorption-desorption hysteresis in biological activated carbon systems.

    Science.gov (United States)

    Abromaitis, V; Racys, V; van der Marel, P; Meulepas, R J W

    2016-04-01

    In Biological Activated Carbon (BAC) systems, persistent organic pollutants can be removed through a combination of adsorption, desorption and biodegradation. These processes might be affected by the presence of other organics, especially by the more abundant easily-biodegradable organics, like acetate. In this research these relations are quantified for the removal of the persistent pharmaceutical metoprolol. Acetate did not affect the adsorption and desorption of metoprolol, but it did greatly enhance the metoprolol biodegradation. At least part of the BAC biomass growing on acetate was also able to metabolise metoprolol, although metoprolol was only converted after the acetate was depleted. The presence of easily-degradable organics like acetate in the feeding water is therefore beneficial for the removal of metoprolol in BAC systems. The isotherms obtained from metoprolol adsorption and desorption experiments showed that BAC systems are subject to hysteresis; for AC bioregeneration to take place the microbial biomass has to reduce the concentration at the AC-biomass interface 2.7 times compared to the concentration at which the carbon was being loaded. However, given the threshold concentration of the MET degrading microorganisms (<0.08 μg/L) versus the average influent concentration (1.3 μg/L), bioregeneration is feasible.

  7. A Transformational Journey: Compositional Changes in Organic Matter during Desorption from Sediments

    Science.gov (United States)

    Matiasek, S. J.; Pellerin, B. A.; Spencer, R.; Bergamaschi, B. A.; Hernes, P.

    2016-12-01

    The release of organic matter (OM) from suspended particles via desorption is a critical component of OM cycling since dissolved OM (DOM) fuels aquatic ecosystems and is a precursor for disinfection by-products formation. This study assessed the elemental and molecular composition of DOM desorbed abiotically from sediments and soils of an irrigated agricultural watershed of northern California. Relative to mineral-bound OM, the released DOM was nitrogen-poor (lower carbon:nitrogen ratios) and depleted in amino acids and lignin phenols (lower carbon-normalized yields). Water-extracted DOM appeared substantially more degraded than its parent particulate OM with increased molar contributions of acidic amino acids, non-protein amino acids, and acidic lignin phenols, all molecular indicators of a more extensively processed OM pool. Desorption processes also significantly altered lignin compositional ratios which help distinguish vascular-plant sources of DOM. Specific optical parameters, including spectral slope, specific UV absorbance at 254 nm (SUVA254), and fluorescence index (FI), did not constitute useful proxies for the desorbed DOM pool, while absorption coefficients and fluorescence peak intensities were strongly correlated with extracted DOM concentrations and composition. This study highlights the profound impact of desorption on DOM composition which, if unaccounted for, could lead to misinterpretations of common biomarkers and optical proxies used to predict DOM sources and reactivity. Our findings suggest that sediments contribute a biogeochemically distinct source of DOM to surface waters, with potential impacts on aquatic health and drinking water quality.

  8. Pyroelectricity Assisted Infrared-Laser Desorption Ionization (PAI-LDI) for Atmospheric Pressure Mass Spectrometry

    Science.gov (United States)

    Li, Yanyan; Ma, Xiaoxiao; Wei, Zhenwei; Gong, Xiaoyun; Yang, Chengdui; Zhang, Sichun; Zhang, Xinrong

    2015-08-01

    A new atmospheric pressure ionization method termed pyroelectricity-assisted infrared laser desorption ionization (PAI-LDI) was developed in this study. The pyroelectric material served as both sample target plate and enhancing ionization substrate, and an IR laser with wavelength of 1064 nm was employed to realize direct desorption and ionization of the analytes. The mass spectra of various compounds obtained on pyroelectric material were compared with those of other substrates. For the five standard substances tested in this work, LiNbO3 substrate produced the highest ion yield and the signal intensity was about 10 times higher than that when copper was used as substrate. For 1-adamantylamine, as low as 20 pg (132.2 fmol) was successfully detected. The active ingredient in (Compound Paracetamol and 1-Adamantylamine Hydrochloride Capsules), 1-adamantylamine, can be sensitively detected at an amount as low as 150 pg, when the medicine stock solution was diluted with urine. Monosaccharide and oligosaccharides in Allium Cepa L. juice was also successfully identified with PAI-LDI. The method did not require matrix-assisted external high voltage or other extra facility-assisted set-ups for desorption/ionization. This study suggested exciting application prospect of pyroelectric materials in matrix- and electricity-free atmospheric pressure mass spectrometry research.

  9. Sorption and desorption of pentachlorophenol to black carbon of three different origins.

    Science.gov (United States)

    Luo, Ling; Lou, Liping; Cui, Xinyi; Wu, Binbin; Hou, Jiaai; Xun, Bei; Xu, Xinhua; Chen, Yingxu

    2011-01-30

    Rice straw charcoal, soot and fly ash (collectively termed "black carbon" or BC), which were found to widely exist in the environment and exhibit strong sorption of many organic compounds, were prepared for this study, and recorded as RC, SC, and FC, respectively. The characterization, sorption isotherm, and the effect of pH (from 3.0 to 9.0) on sorption capacity of each BC were investigated. It is demonstrated that RC possessed the largest surface area (234.9 m(2)/g), the highest porosity (0.4392 mL/g), and the largest amount of functional groups (2.995 mmol/g) of all. All the Freundlich, Langmuir and Dual-mode model can fit the sorption data of each BC well. The pH value could apparently affect the sorption capacity of pentachlorophenol (PCP) to BCs, which reached maximum value at pH 4.0. Furthermore, in order to validate the effect of pH on desorption capacity, we designed sorption-desorption cycle experiments at pH 9.0 and then pH 7.0, and found that the effect of pH on irreversible sorption and hysteresis effects were significant. As pH value decreasing from 9.0 to 7.0, the irreversible sorption capacities for RC, FC, and SC increased, and the desorption hysteresis index (H) values of PCP increased approximately 3 times for each BC.

  10. Optical breathing of nano-porous antireflective coatings through adsorption and desorption of water.

    Science.gov (United States)

    Nielsen, Karsten H; Kittel, Thomas; Wondraczek, Katrin; Wondraczek, Lothar

    2014-10-13

    We report on the direct consequences of reversible water adsorption on the optical performance of silica-based nanoporous antireflective (AR) coatings as they are applied on glass in photovoltaic and solar thermal energy conversion systems. In situ UV-VIS transmission spectroscopy and path length measurements through high-resolution interferometric microscopy were conducted on model films during exposure to different levels of humidity and temperature. We show that water adsorption in the pores of the film results in a notable increase of the effective refractive index of the coating. As a consequence, the AR effect is strongly reduced. The temperature regime in which the major part of the water can be driven-out rapidly lies in the range of 55°C and 135°C. Such thermal desorption was found to increase the overall transmission of a coated glass by ~ 1%-point. As the activation energy of isothermal desorption, we find a value of about 18 kJ/mol. Within the experimental range of our data, the sorption and desorption process is fully reversible, resulting in optical breathing of the film. Nanoporous AR films with closed pore structure or high hydrophobicity may be of advantage for maintaining AR performance under air exposure.

  11. Optical breathing of nano-porous antireflective coatings through adsorption and desorption of water

    Science.gov (United States)

    Nielsen, Karsten H.; Kittel, Thomas; Wondraczek, Katrin; Wondraczek, Lothar

    2014-10-01

    We report on the direct consequences of reversible water adsorption on the optical performance of silica-based nanoporous antireflective (AR) coatings as they are applied on glass in photovoltaic and solar thermal energy conversion systems. In situ UV-VIS transmission spectroscopy and path length measurements through high-resolution interferometric microscopy were conducted on model films during exposure to different levels of humidity and temperature. We show that water adsorption in the pores of the film results in a notable increase of the effective refractive index of the coating. As a consequence, the AR effect is strongly reduced. The temperature regime in which the major part of the water can be driven-out rapidly lies in the range of 55°C and 135°C. Such thermal desorption was found to increase the overall transmission of a coated glass by ~ 1%-point. As the activation energy of isothermal desorption, we find a value of about 18 kJ/mol. Within the experimental range of our data, the sorption and desorption process is fully reversible, resulting in optical breathing of the film. Nanoporous AR films with closed pore structure or high hydrophobicity may be of advantage for maintaining AR performance under air exposure.

  12. Matrix-assisted laser desorption mass spectrometry of gas-phase peptide-metal complexes

    Science.gov (United States)

    Hortal, Ana R.; Hurtado, Paola; Martínez-Haya, Bruno

    2008-12-01

    Cation attachment to a model peptide has been investigated in matrix-assisted laser desorption experiments. Angiotensin I (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu) is chosen as a system for study, and Cu2+ and K+ salts are used as cationizing agents. Three fundamentally different types of samples are investigated: (1) a crystalline sample of Ang I, metal salt and MALDI matrix, prepared with the conventional dried droplet method; (2) a solvent-free fine powder mixture of the same three compounds, and (3) a solution of the angiotensin and the metal salt in an ionic liquid matrix (a molten organic salt that acts as a MALDI active solvent). Effective protonation and cationization of the peptide are achieved with the three methods. The transition metal systematically provides more efficient cationization than the alkali metal. At sufficiently high concentration of the salt, the attachment of up to four copper cations to the angiotensin is observed in the MALDI spectrum. In contrast, only one K+ cation is efficiently bound to the peptide. For a given salt concentration, the highest degree of cationization is obtained in the laser desorption from the ionic liquid matrix. This is attributed to the efficient transfer of free metal cations to the desorption plume, where the complexation takes place.

  13. Adsorption-desorption behavior of acetochlor to soils in the presence of some environmental substances

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The behavior of herbicide acetochlor adsorption-desorption to soil in the presence of humic acid (HA), anionic surfactant sodium dodecylbenzene sulfonate (SDBS), cationic surfactant hexadecyltrimethyl-ammonium bromide (HDAB) and NH4NO3 as a chemical fertilizer was studied. Observed acetochlor adsorption isotherm were well described using Freundlich isotherm equation, from which the desorption isotherm equation has been deduced. The deduced equation can more directly describe acetochlor desorption process. The results showed that the enhance of acetochlor adsorption capacity by solid HA was greater than by soluble HA. The presence of NH4 NO3 can slightly enhance acetochlor adsorption to soil by comparison with that measured in NH4NO3-free solution. In soil-water system, surfactant-acetochlor interaction is very complex, and the surfactant adsorptions as well as acetochlor adsorption need to be considered. When acetochlor-soil suspensions contained lower concentration SDBS or HDAB (40 mg/L), Kf for acetochlor adsorption was decreased in comparison to that measured in SDBSor HDAB-free solution. When acetochlor-soil suspensions contained higher concentration SDBS or HDAB (corresponding 1400 mg/L or 200 mg/L), Kf for acetochlor adsorption was increased in comparison to that measured in SDBS- or HDAB-free solution.

  14. Adsorption-desorption behavior of atrazine on agricultural soils in China.

    Science.gov (United States)

    Yue, Lin; Ge, ChengJun; Feng, Dan; Yu, Huamei; Deng, Hui; Fu, Bomin

    2017-07-01

    Adsorption and desorption are important processes that affect atrazine transport, transformation, and bioavailability in soils. In this study, the adsorption-desorption characteristics of atrazine in three soils (laterite, paddy soil and alluvial soil) were evaluated using the batch equilibrium method. The results showed that the kinetics of atrazine in soils was completed in two steps: a "fast" adsorption and a "slow" adsorption and could be well described by pseudo-second-order model. In addition, the adsorption equilibrium isotherms were nonlinear and were well fitted by Freundlich and Langmuir models. It was found that the adsorption data on laterite, and paddy soil were better fitted by the Freundlich model; as for alluvial soil, the Langmuir model described it better. The maximum atrazine sorption capacities ranked as follows: paddy soil>alluvial soil>laterite. Results of thermodynamic calculations indicated that atrazine adsorption on three tested soils was spontaneous and endothermic. The desorption data showed that negative hysteresis occurred. Furthermore, lower solution pH value was conducive to the adsorption of atrazine in soils. The atrazine adsorption in these three tested soils was controlled by physical adsorption, including partition and surface adsorption. At lower equilibrium concentration, the atrazine adsorption process in soils was dominated by surface adsorption; while with the increase of equilibrium concentration, partition was predominant. Copyright © 2016. Published by Elsevier B.V.

  15. Adsorption and desorption of dissolved organic matter by carbon nanotubes: Effects of solution chemistry.

    Science.gov (United States)

    Engel, Maya; Chefetz, Benny

    2016-06-01

    Increasing use of carbon nanotubes (CNTs) has led to their introduction into the environment where they can interact with dissolved organic matter (DOM). This study focuses on solution chemistry effects on DOM adsorption/desorption processes by single-walled CNTs (SWCNTs). Our data show that DOM adsorption is controlled by the attachment of DOM molecules to the SWCNTs, and that the initial adsorption rate is dependent on solution parameters. Adsorbed amount of DOM at high ionic strength was limited, possibly due to alterations in SWCNT bundling. Desorption of DOM performed at low pH resulted in additional DOM adsorption, whereas at high pH, adsorbed DOM amount decreased. The extent of desorption conducted at increased ionic strength was dependent on pre-adsorbed DOM concentration: low DOM loading stimulated additional adsorption of DOM, whereas high DOM loading facilitated release of adsorbed DOM. Elevated ionic strength and increased adsorbed amount of DOM reduced the oxidation temperature of the SWCNTs, suggesting that changes in the assembly of the SWCNTs had occurred. Moreover, DOM-coated SWCNTs at increased ionic strength provided fewer sites for atrazine adsorption. This study enhances our understanding of DOM-SWCNT interactions in aqueous systems influenced by rapid changes in salinity, and facilitates potential use of SWCNTs in water-purification technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Searching out the hydrogen absorption/desorption limiting reaction factors: Strategies allowing to increase kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Zeaiter, Ali, E-mail: ali.zeaiter@femto-st.fr; Chapelle, David; Nardin, Philippe

    2015-10-05

    Highlights: • A macro scale thermodynamic model that simulates the response of a FeTi-X hydride tank is performed, and validated experimentally. • A sensibility study to identify the most influent input variables that can changes very largely the reaction rate. - Abstract: Hydrogen gas has become one of the most promising energy carriers. Main breakthrough concerns hydrogen solid storage, specially based on intermetallic material use. Regarding the raw material abundance and cost, the AB type alloy FeTi is an auspicious candidate to store hydrogen. Its absorption/desorption kinetics is a basic hindrance to common use, compared with more usual hydrides. First, discussions based on literature help us identifying the successive steps leading to metal hydriding, and allow to introduce the physical parameters which drive or limit the reaction. This analysis leads us to suggest strategies in order to increase absorption/desorption kinetics. Attention is then paid to a thermofluidodynamic model, allowing to describe a macroscopic solid storage reactor. Thus, we can achieve a simulation which describes the overall reaction inside the hydrogen reactor and, by varying the sub-mentioned parameters (thermal conductivity, the powder granularity, environment heat exchange…), we attempt to hierarchy the reaction limiting factors. These simulations are correlated to absorption/desorption experiments for which pressure, temperature and hydrogen flow are recorded.

  17. Arsenite oxidation by a poorly-crystalline manganese oxide. 3. Arsenic and manganese desorption.

    Science.gov (United States)

    Lafferty, Brandon J; Ginder-Vogel, Matthew; Sparks, Donald L

    2011-11-01

    Arsenic (As) mobility in the environment is greatly affected by its oxidation state and the degree to which it is sorbed on metal oxide surfaces. Manganese oxides (Mn oxides) have the ability to decrease overall As mobility both by oxidizing toxic arsenite (As(III)) to less toxic arsenate (As(V)), and by sorbing As. However, the effect of competing ions on the mobility of As sorbed on Mn-oxide surfaces is not well understood. In this study, desorption of As(V) and As(III) from a poorly crystalline phyllomanganate (δ-MnO(2)) by two environmentally significant ions is investigated using a stirred-flow technique and X-ray absorption spectroscopy (XAS). As(III) is not observed in solution after desorption under any conditions used in this study, agreeing with previous studies showing As sorbed on Mn-oxides exists only as As(V). However, some As(V) is desorbed from the δ-MnO(2) surface under all conditions studied, while neither desorptive used in this study completely removes As(V) from the δ-MnO(2) surface.

  18. Surface reconstruction and thermal desorption: {O}/{Ag(110) } an experimental study

    Science.gov (United States)

    Canepa, M.; Salvietti, M.; Traverso, M.; Mattera, L.

    1995-07-01

    We have studied the associative desorption of oxygen from well-defined O( n×1)Ag(110) phases ( n ranging from 8 to 2) by thermal desorption mass spectrometry. Desorption peak profiles have been compared with calculations based on a lattice-gas model [V.P. Zhdanov, Surf. Sci. 277 (1992) 155] which takes into account the missing-row reconstruction of the substrate and adsorbate-adsorbate interactions along independent OAgO rows. The model works well at low coverage accurately reproducing the peak profiles. For the O(8 × 1), O(6 × 1) and O(4 × 1) phases, assuming a value of v = 10 15 s -1 for the pre-factor, values of ≈ 39 kcal/mol for the activation energy and ≈ -2.5 kcal/mol for the OO effective oxygen-oxygen interaction along OAgO rows are obtained. At high coverage the assumption of independence of OAgO chains is no longer valid and repulsive interactions perpendicularly to the chains have to be taken into account.

  19. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identification of mycobacteria in routine clinical practice

    National Research Council Canada - National Science Library

    El Khéchine, Amel; Couderc, Carine; Flaudrops, Christophe; Raoult, Didier; Drancourt, Michel

    2011-01-01

    .... Matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS) has previously been proven to effectively identify mycobacteria grown in high-concentration inocula from collections...

  20. Recovery of naringin from kinnow (Citrus reticulata Blanco) peels by adsorption–desorption technique using an indigenous resin

    Indian Academy of Sciences (India)

    M LAXMI DEEPAK BHATLU; SATYA VIR SINGH; ASHOK KUMAR VERMA

    2017-01-01

    A process technology has been developed for recovery of naringin from kinnow (citrus) peels,which is a waste. The kinnow peels were boiled with water to extract naringin into water. It was adsorbed on an indigenous macroporous resin, Indion PA-500. Naringin was recovered from the saturated resin by desorption with ethanol as a solvent. The equilibrium and kinetic studies for both adsorption and desorption are presented.The Langmuir isotherm described the adsorption equilibrium data. However, desorption data were best described by the Toth isotherm. Adsorption and desorption kinetic data were found to follow a pseudo-secondorder rate equation and second-order rate equation, respectively. Recovery of naringin was about 49% w/w (based on naringin present in peel-boiled extract). The purity of final products was 91–94% w/w.