Adsorption of ammonium and phosphate by feather protein based semi-interpenetrating polymer networks hydrogel as a controlled-release fertilizer.

Science.gov (United States)

Su, Yuan; Liu, Jia; Yue, Qinyan; Li, Qian; Gao, Baoyu

2014-01-01

A new feather protein-grafted poly(potassium acrylate)/polyvinyl alcohol (FP-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was produced through graft copolymerization with FP as a basic macromolecular skeletal material, acrylic acid as a monomer and PVA as a semi-IPNs polymer. The adsorption of ammonium and phosphate ions from aqueous solution using the new hydrogel as N and P controlled-release fertilizer with water-retention capacity was studied. The effects of pH value, concentration, contact time and ion strength on NH4+ and PO3-4 removal by FP-g-PKA/PVA semi-IPNs hydrogel were investigated using batch adsorption experiments. The results indicated that the hydrogel had high adsorption capacities and fast adsorption rates for NH4+ and PO3-4 in wide pH levels ranging from 4.0 to 9.0. Kinetic analysis presented that both NH4+ and PO3-4 removal were closely fitted with the pseudo-second-order model. Furthermore, the adsorption isotherms of hydrogel were best represented by the Freundlich model. The adsorption-desorption experimental results showed the sustainable stability of FP-g-PKA/PVA semi-IPNs hydrogel for NH4+ and PO3-4 removal. Overall, FP-g-PKA/PVA could be considered as an efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer.

Novel composite membrane coated with a poly(diallyldimethylammonium chloride)/urushi semi-interpenetrating polymer network for non-aqueous redox flow battery application

Science.gov (United States)

Cho, Eunhae; Won, Jongok

2016-12-01

Novel composite membranes of a semi-interpenetrating network (semi-IPN) coated on the surfaces of a porous Celgard 2400 support are prepared and investigate for application in a non-aqueous redox flow battery (RFB). A natural polymer, urushi, is used for the matrix because of its high mechanical robustness, and poly(diallyldimethylammonium chloride) (PDDA) provides anionic exchange sites. The PDDA/urushi (P/U) semi-IPN film is prepared by the photo polymerization of urushiol in the presence of PDDA. The thin layer composed of the P/U semi-IPN on the porous support provides selectivity while maintaining the ion conductivity. The coulombic and energy efficiencies increase with increasing amounts of PDDA in the P/U semi-IPN layer, and the values reach 69.5% and 42.5%, respectively, for the one containing 40 wt% of PDDA. These values are substantially higher than those of the Neosepta AHA membrane and the Celgard membrane, indicating that the selective layer reduces the crossover of the redox active species through the membrane. This result implies that the formation of composite membranes using semi-IPN selective layers on the dimensionally stable porous membrane enable the successful use of a non-aqueous RFB for future energy storage systems.

Some experiments to study diffusive transport through a semi interpenetrating polymeric network in the absence and presence of aqueous electrolytes

Science.gov (United States)

Biswas, Pritha; Das, Atreyee; Yasmin, Tanvee; Kanjilal, Baishali; Chakrabarti, Haimanti

2018-05-01

The study of ion transport in biological system has become a topic of great current interest. This work presents the diffusive transport properties through a typical semi interpenetrating polymeric network (SIPN) which mimics many characteristic features of the walls of human food pipes. The SIPN matrix has been synthesised from Polyvinyl alcohol, Acrylamide monomer, Glutaraldehyde and Ammonium Per sulphate in our laboratory is utilised to study the diffusive transport in the absence and presence of aqueous electrolyte (KCl) at varying concentrations. The diffusivity of the SIPN polymer hydrogel was estimated by the `Theory of Elastomer' to get an insight into process of Potassium and Chlorine ion transport through the SIPN.

Hydrolytic And Enzymatic Degradation Characteristics Of Biodegradable Aliphatic Polysters

Institute of Scientific and Technical Information of China (English)

LI Suming

2004-01-01

Aliphatic polyesters, especially those derived from lactide (PLA), glycolide (PGA) and ε-caprolactone (PCL), are being investigated worldwide for applications in the field of surgery (suture material, devices for internal bone fracture fixation), pharmacology (sustained drug delivery systems), and tissue engineering (scaffold for tissue regeneration) [1,2]. This is mainly due to their good biocompatibility and variable degradability. These polymers present also a growing interest for environmental applications in agriculture (mulch films) and in our everyday life (packaging material)as the development of biodegradable materials is now considered as one of the potential solutions to the problem of plastic waste management.For both biomedical and environmental applications, it is of major importance to understand the degradation characteristics of the polymers. The hydrolytic degradation of aliphatic polyesters has been investigated by many research groups. Our group has shown that degradation of PLAGA large size devices is faster inside than at the surface. This heterogeneous degradation is due to the autocatalytic effect of carboxylic endgroups formed by ester bond cleavage. Moreover,degradation-induced morphological and compositional changes were also elucidated. In the case of PCL, the hydrolytic degradation is very slow due to its hydrophobicity and crystallinity.The enzymatic degradation of these polymers has been investigated by a number of authors. A specific enzyme, proteinase K, has been shown to have significant effects on PLA degradation. This enzyme preferentially degrade L-lactate units as opposed to D-lactate ones, amorphous zones as opposed to crystalline ones [3]. The enzymatic degradation of PCL polymers has also been investigated. A number of lipase-type enzymes were found to significantly accelerate the degradation of PCL despite its high crystallinity. In the case of PLA/PCL blends, the two components exhibited well separated crystalline domains

Ion pair reinforced semi-interpenetrating polymer network for direct methanol fuel cell applications.

Science.gov (United States)

Fang, Chunliu; Julius, David; Tay, Siok Wei; Hong, Liang; Lee, Jim Yang

2012-06-07

This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs.

In-Vitro Enzymatic Degradation of γ-irradiated Porous Chitosan Scaffold: Crystallinity and degree of deacetylation

International Nuclear Information System (INIS)

Ismail Zainol; Azreena Mastor; Suhaida Md Ghani; Ahmad Fuad Yahya; Hazizan Md Akil

2009-01-01

Full text: Enzymatic degradation behavior of porous chitosan membrane was carried out in vitro by using enzymatic hydrolysis of chitosan in lysozyme solution. Chitosan was first modified by reducing its molecular weight by gamma (γ) radiation in the solid state. The chitosan powder was irradiated with gamma Co 60 source with various doses of 10, 25, 50 and 100 kGy. The molecular weight of irradiated chitosan was measured using visco metric method. The modified chitosan was transform into a porous membrane by lyophilization method. Degree of deacetylation (DD) and crystallinity of samples were measured using FTIR and XRD respectively on both gamma irradiated and enzymatic degradation samples. The results suggested that the irradiated chitosan become less crystalline without changes in DD. The enzymatic degradation of chitosan however shows an increment in DD and crystallinity. (author)

Enzymatic degradation studies of xylogalacturonans from apple and potato, using xylogalacturonan hydrolase

NARCIS (Netherlands)

Zandleven, J.S.; Beldman, G.; Bosveld, M.; Schols, H.A.; Voragen, A.G.J.

2006-01-01

Action of xylogalacturonan hydrolase (XGH) towards xylogalacturonan (XGA) present in the alkali saponified ¿modified hairy regions¿ from potato and apple pectin was studied. Analysis of enzymatic degradation products from XGA in these complex pectins demonstrated that the degradable

Enzymatic degradation behavior of nanoclay reinforcedbiodegradable PLA/PBSA blend composites

CSIR Research Space (South Africa)

Malwela, T

2015-06-01

Full Text Available Journal of Biological Macromolecules Vol. 77, 131-142 Enzymatic degradation behavior of nanoclay reinforcedbiodegradable PLA/PBSA blend composites Thomas Malwelaa,b, Suprakas Sinha Raya,b,∗ aDST/CSIR National Centre for Nanostructured Materials...

Polymer matrix of fiber-reinforced composites: Changes in the semi-interpenetrating polymer network during the shelf life.

Science.gov (United States)

Khan, Aftab A; Al-Kheraif, Abdulaziz A; Al-Shehri, Abdullah M; Säilynoja, Eija; Vallittu, Pekka K

2018-02-01

This laboratory study was aimed to characterize semi-interpenetrating polymer network (semi-IPN) of fiber-reinforced composite (FRC) prepregs that had been stored for up to two years before curing. Resin impregnated prepregs of everStick C&B (StickTech-GC, Turku, Finland) glass FRC were stored at 4°C for various lengths of time, i.e., two-weeks, 6-months and 2-years. Five samples from each time group were prepared with a light initiated free radical polymerization method, which were embedded to its long axis in self-curing acrylic. The nanoindentation readings on the top surface toward the core of the sample were made for five test groups, which were named as "stage 1-5". To evaluate the nanohardness and modulus of elasticity of the polymer matrix, a total of 4 slices (100µm each) were cut from stage 1 to stage 5. Differences in nanohardness values were evaluated with analysis of variance (ANOVA), and regression model was used to develop contributing effect of the material's different stages to the total variability in the nanomechanical properties. Additional chemical and thermal characterization of the polymer matrix structure of FRC was carried out. It was hypothesized that time of storage may have an influence on the semi-IPN polymer structure of the cured FRC. The two-way ANOVA test revealed that the storage time had no significant effect on the nanohardness of FRC (p = 0.374). However, a highly significant difference in nanohardness values was observed between the different stages of FRC (Pprepregs might be due to phase-segregation of components of semi-IPN structure of FRC prepregs before their use. This may have an influence to the surface bonding properties of the cured FRC. Copyright © 2017 Elsevier Ltd. All rights reserved.

Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

Science.gov (United States)

Shahidi, Nima

Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media

Enhanced enzymatic cellulose degradation by cellobiohydrolases via product removal

DEFF Research Database (Denmark)

Ahmadi Gavlighi, Hassan; Meyer, Anne S.; Mikkelsen, Jørn Dalgaard

2013-01-01

Product inhibition by cellobiose decreases the rate of enzymatic cellulose degradation. The optimal reaction conditions for two Emericella (Aspergillus) nidulans-derived cellobiohydrolases I and II produced in Pichia pastoris were identified as CBHI: 52 °C, pH 4.5–6.5, and CBHII: 46 °C, pH 4.......8. The optimum in a mixture of the two was 50 °C, pH 4.9. An almost fourfold increase in enzymatic hydrolysis yield was achieved with intermittent product removal of cellobiose with membrane filtration (2 kDa cut-off): The conversion of cotton cellulose after 72 h was ~19 % by weight, whereas the conversion...

Influence of Teflon substrate on crystallization and enzymatic degradation of polymorphic poly(butylene adipate)

DEFF Research Database (Denmark)

Ning, Zhenbo; Nielsen, Ronnie Bo Højstrup; Zhao, Lifen

2014-01-01

for PBA beta crystals between neither the oriented nor the non-oriented Teflon films. The enzymatic degradation rate of PBA films was not determined by the epitaxial crystallization, in fact it was still dependent on the polymorphic crystal structure of PBA. The morphological changes of PBA films after...... enzymatic degradation confirmed again that the epitaxial crystallization only occurred for the PBA film with alpha crystal structure which was produced by being sandwiched between oriented Teflon films, and it happened only on the surface of PBA films....

Semi-interpenetrating network of acrylamide-grafted-sodium alginate microspheres for controlled release of diclofenac sodium, preparation and characterization.

Science.gov (United States)

Al-Kahtani, Ahmed A; Sherigara, B S

2014-03-01

The semi-interpenetrating networks (semi-IPNs) of acrylamide grafted sodium alginate (AAm-g-NaAlg) microspheres (MPs) were prepared by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinking agent. The grafting of acrylamide onto sodium alginate was prepared by free-radical graft polymerization using ceric ammonium nitrate (CAN) as initiator at three acrylamide concentrations with monomer to polymer ratio of 1:1, 2:1 and 3:1, respectively. The grafting efficiency was found to be 91%. The produced MPs are almost spherical in nature with smooth surfaces. Diclofenac sodium (DS), an anti-inflammatory drug was successfully encapsulated into the MPs. The encapsulation efficiency was found to vary between 83% and 95%. The MPs were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The diffusion coefficient (D) was dependent upon the amount of crosslinking agent (GA) and amount of grafting ratio in the matrix. The rate of release was found to be dependent on the amount of GA, AAm:NaAlg grafting ratio and % drug loading in the MPs. The release data have been fitted to an empirical equation to investigate the diffusional exponent (n), which indicated that the release mechanism from MPs follows the super Case II transport. Copyright © 2013 Elsevier B.V. All rights reserved.

Injectable glycosaminoglycan-protein nano-complex in semi-interpenetrating networks: A biphasic hydrogel for hyaline cartilage regeneration.

Science.gov (United States)

Radhakrishnan, Janani; Subramanian, Anuradha; Sethuraman, Swaminathan

2017-11-01

Articular hyaline cartilage regeneration remains challenging due to its less intrinsic reparability. The study develops injectable biphasic semi-interpenetrating polymer networks (SIPN) hydrogel impregnated with chondroitin sulfate (ChS) nanoparticles for functional cartilage restoration. ChS loaded zein nanoparticles (∼150nm) prepared by polyelectrolyte-protein complexation were interspersed into injectable SIPNs developed by blending alginate with poly(vinyl alcohol) and calcium crosslinking. The hydrogel exhibited interconnected porous microstructure (39.9±5.8μm pore diameter, 57.7±5.9% porosity), 92% swellability and >350Pa elastic modulus. Primary chondrocytes compatibility, chondrocyte-matrix interaction with cell-cell clustering and spheroidal morphology was demonstrated in ChS loaded hydrogel and long-term (42days) proliferation was also determined. Higher fold expression of cartilage-specific genes sox9, aggrecan and collagen-II was observed in ChS loaded hydrogel while exhibiting poor expression of collagen-I. Immunoblotting of aggregan and collagen II demonstrate favorable positive influence of ChS on chondrocytes. Thus, the injectable biphasic SIPNs could be promising composition-mimetic substitute for cartilage restoration at irregular defects. Copyright © 2017 Elsevier Ltd. All rights reserved.

An interpenetrating HA/G/CS biomimic hydrogel via Diels-Alder click chemistry for cartilage tissue engineering.

Science.gov (United States)

Yu, Feng; Cao, Xiaodong; Zeng, Lei; Zhang, Qing; Chen, Xiaofeng

2013-08-14

In order to mimic the natural cartilage extracellular matrix, a novel biological degradable interpenetrating network hydrogel was synthesized from the gelatin (G), hyaluronic acid (HA) and chondroitin sulfate (CS) by Diels-Alder "click" chemistry. HA was modified with furylamine and G was modified with furancarboxylic acid respectively. (1)H NMR spectra and elemental analysis showed that the substitution degrees of HA-furan and G-furan were 71.5% and 44.5%. Then the hydrogels were finally synthesized by cross-linking furan-modified HA and G derivatives with dimaleimide poly(ethylene glycol) (MAL-PEG-MAL). The mechanical and degradation properties of the hydrogels could be tuned simply through varying the molar ratio between furan and maleimide. Rheological, mechanical and degradation studies demonstrated that the Diels-Alder "click" chemistry is an efficient method for preparing high performance biological interpenetrating hydrogels. This biomimic hydrogel with improved mechanical properties could have great potential applications in cartilage tissue engineering. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of Hydroxyl Monomers on the Enzymatic Degradation of Poly(ethylene succinate, Poly(butylene succinate, and Poly(hexylene succinate

Directory of Open Access Journals (Sweden)

Zhenhui Bai

2018-01-01

Full Text Available Poly(ethylene succinate (PES, poly(butylene succinate (PBS, and poly(hexylene succinate (PHS, were synthesized using succinic acid and different dihydric alcohols as materials. Enzymatic degradability by cutinase of the three kinds of polyesters was studied, as well as their solid-state properties. The biodegradation behavior relied heavily on the distance between ester groups, crystallinity, and the hydrophilicity-hydrophobicity balance of polyester surfaces. The weight loss through degradation of the three kinds of polyesters with different hydroxyl monomers took place in the order PHS > PBS > PES. The degradation behavior of the polyesters before and after degradation was analyzed by scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The decrease in relative intensity at 1800–1650 estedpolyesters were degraded simultaneously. The frequencies of the crystalline and amorphous bands were almost identical before and after degradation. Thus, enzymatic degradation did not change the crystalline structure but destroyed it, and the degree of crystallinity markedly decreased. The molecular weight and polydispersity index only changed slightly. The thermal stability of the three kinds of polyesters decreased during enzymatic degradation.

Injectable and inherently vascularizing semi-interpenetrating polymer network for delivering cells to the subcutaneous space.

Science.gov (United States)

Mahou, Redouan; Zhang, David K Y; Vlahos, Alexander E; Sefton, Michael V

2017-07-01

Injectable hydrogels are suitable for local cell delivery to the subcutaneous space, but the lack of vasculature remains a limiting factor. Previously we demonstrated that biomaterials containing methacrylic acid promoted vascularization. Here we report the preparation of a semi-interpenetrating polymer network (SIPN), and its evaluation as an injectable carrier to deliver cells and generate blood vessels in a subcutaneous implantation site. The SIPN was prepared by reacting a blend of vinyl sulfone-terminated polyethylene glycol (PEG-VS) and sodium polymethacrylate (PMAA-Na) with dithiothreitol. The swelling of SIPN was sensitive to the PMAA-Na content but only small differences in gelation time, permeability and stiffness were noted. SIPN containing 20 mol% PMAA-Na generated a vascular network in the surrounding tissues, with 2-3 times as many vessels as was obtained with 10 mol% PMAA-Na or PEG alone. Perfusion studies showed that the generated vessels were perfused and connected to the host vasculature as early as seven days after transplantation. Islets embedded in SIPN were viable and responsive to glucose stimulation in vitro. In a proof of concept study in a streptozotocin-induced diabetic mouse model, a progressive return to normoglycemia was observed and the presence of insulin positive islets was confirmed when islets were embedded in SIPN prior to delivery. Our approach proposes a biomaterial-mediated strategy to deliver cells while enhancing vascularization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enzymatic Systems for Cellulose Acetate Degradation

Directory of Open Access Journals (Sweden)

Oskar Haske-Cornelius

2017-09-01

Full Text Available Cellulose acetate (CA-based materials, like cigarette filters, contribute to landscape pollution challenging municipal authorities and manufacturers. This study investigates the potential of enzymes to degrade CA and to be potentially incorporated into the respective materials, enhancing biodegradation. Deacetylation studies based on Liquid Chromatography-Mass Spectrometry-Time of Flight (LC-MS-TOF, High Performance Liquid Chromatography (HPLC, and spectrophotometric analysis showed that the tested esterases were able to deacetylate the plasticizer triacetin (glycerol triacetate and glucose pentaacetate (cellulose acetate model compound. The most effective esterases for deacetylation belong to the enzyme family 2 (AXE55, AXE 53, GAE, they deacetylated CA with a degree of acetylation of up to 1.8. A combination of esterases and cellulases showed synergistic effects, the absolute glucose recovery for CA 1.8 was increased from 15% to 28% when an enzymatic deacetylation was performed. Lytic polysaccharide monooxygenase (LPMO, and cellobiohydrolase were able to cleave cellulose acetates with a degree of acetylation of up to 1.4, whereas chitinase showed no activity. In general, the degree of substitution, chain length, and acetyl group distribution were found to affect CA degradation. This study shows that, for a successful enzyme-based deacetylation system, a cocktail of enzymes, which will randomly cleave and generate shorter CA fragments, is the most suitable.

Facilitating the enzymatic saccharification of pulped bamboo residues by degrading the remained xylan and lignin-carbohydrates complexes.

Science.gov (United States)

Huang, Caoxing; He, Juan; Li, Xin; Min, Douyong; Yong, Qiang

2015-09-01

Kraft pulping was performed on bamboo residues and its impact on the chemical compositions and the enzymatic digestibility of the samples were investigated. To improve the digestibility of sample by degrading the xylan and lignin-carbohydrates complexes (LCCs), xylanase and α-L-arabinofuranosidase (AF) were supplemented with cellulase. The results showed more carbohydrates were remained in the samples pulped with low effective alkali (EA) charge, compared to conventional kraft pulping. When 120 IU/g xylanase and 15 IU/g AF were supplemented with 20 FPU/g cellulase, the xylan degradation yield of the sample pulped with 12% EA charge increased from 68.20% to 88.35%, resulting in an increased enzymatic saccharification efficiency from 58.98% to 83.23%. The amount of LCCs in this sample decreased from 8.63/100C9 to 2.99/100C9 after saccharification with these enzymes. The results indicated that degrading the remained xylan and LCCs in the pulp could improve its enzymatic digestibility. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sexual crossing of thermophilic fungus Myceliophthora heterothallica improved enzymatic degradation of sugar beet pulp

NARCIS (Netherlands)

Aguilar-Pontes, Maria Victoria; Zhou, Miaomiao; van der Horst, Sjors; Theelen, Bart; de Vries, Ronald P.; van den Brink, Joost

2016-01-01

Background Enzymatic degradation of plant biomass requires a complex mixture of many different enzymes. Like most fungi, thermophilic Myceliophthora species therefore have a large set of enzymes targeting different linkages in plant polysaccharides. The majority of these enzymes have not been

Enzymatic cell wall degradation of high-pressure-homogenized tomato puree and its effect on lycopene bioaccessibility.

Science.gov (United States)

Palmero, Paola; Colle, Ines; Lemmens, Lien; Panozzo, Agnese; Nguyen, Tuyen Thi My; Hendrickx, Marc; Van Loey, Ann

2016-01-15

High-pressure homogenization disrupts cell structures, assisting carotenoid release from the matrix and subsequent micellarization. However, lycopene bioaccessibility of tomato puree upon high-pressure homogenization is limited by the formation of a process-induced barrier. In this context, cell wall-degrading enzymes were applied to hydrolyze the formed barrier and enhance lycopene bioaccessibility. The effectiveness of the enzymes in degrading their corresponding substrates was evaluated (consistency, amount of reducing sugars, molar mass distribution and immunolabeling). An in vitro digestion procedure was applied to evaluate the effect of the enzymatic treatments on lycopene bioaccessibility. Enzymatic treatments with pectinases and cellulase were proved to effectively degrade their corresponding cell wall polymers; however, no further significant increase in lycopene bioaccessibility was obtained. A process-induced barrier consisting of cell wall material is not the only factor governing lycopene bioaccessibility upon high-pressure homogenization. © 2015 Society of Chemical Industry.

Enzymatic degradation behavior and cytocompatibility of silk fibroin-starch-chitosan conjugate membranes

Energy Technology Data Exchange (ETDEWEB)

Baran, Erkan T., E-mail: erkantur@metu.edu.tr; Tuzlakoglu, Kadriye, E-mail: kadriye@dep.uminho.pt; Mano, Joao F., E-mail: jmano@dep.uminho.pt; Reis, Rui L., E-mail: rgreis@dep.uminho.pt

2012-08-01

The objective of this study was to investigate the influence of silk fibroin and oxidized starch conjugation on the enzymatic degradation behavior and the cytocompatability of chitosan based biomaterials. The tensile stress of conjugate membranes, which was at 50 Megapascal (MPa) for the lowest fibroin and starch composition (10 weight percent (wt.%)), was decreased significantly with the increased content of fibroin and starch. The weight loss of conjugates in {alpha}-amylase was more notable when the starch concentration was the highest at 30 wt.%. The conjugates were resistant to the degradation by protease and lysozyme except for the conjugates with the lowest starch concentration. After 10 days of cell culture, the proliferation of osteoblast-like cells (SaOS-2) was stimulated significantly by higher fibroin compositions and the DNA synthesis on the conjugate with the highest fibroin (30 wt.%) was about two times more compared to the native chitosan. The light microscopy and the image analysis results showed that the cell area and the lengths were decreased significantly with higher fibroin/chitosan ratio. The study proved that the conjugation of fibroin and starch with the chitosan based biomaterials by the use of non-toxic reductive alkylation crosslinking significantly improved the cytocompatibility and modulated the biodegradation, respectively. - Highlights: Black-Right-Pointing-Pointer Silk fibroin, starch and chitosan conjugates were prepared by reductive alkylation. Black-Right-Pointing-Pointer The enzymatic biodegradation and the cytocompatibility of conjugates were tested. Black-Right-Pointing-Pointer The conjugate with 30% starch composition was degraded by {alpha}-amylase significantly. Black-Right-Pointing-Pointer Higher starch composition in conjugates prevented protease and lysozyme degradation. Black-Right-Pointing-Pointer Fibroin incorporation effectively increased the cell proliferation of conjugates.

Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

Science.gov (United States)

Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu

2014-07-17

A novel wheat straw cellulose-g-poly(potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was prepared by polymerizing wheat straw and an aqueous solution of acrylic acid (AA), and further semi-interpenetrating with PVA occurred during the chemosynthesis. The swelling and deswelling properties of WSC-g-PKA/PVA semi-IPNs hydrogel and WSC-g-PKA hydrogel were studied and compared in various pH solutions, salt solutions, temperatures, particle sizes and ionic strength. The results indicated that both hydrogels had the largest swelling capacity at pH=6, and the effect of ions on the swelling of hydrogels was in the order: Na(+)>K(+)>Mg(2+)>Ca(2+). The Schott's pseudo second order model can be effectively used to evaluate swelling kinetics of hydrogels. Moreover, the semi-IPNs hydrogel had improved swelling-deswelling properties compared with that of WSC-g-PKA hydrogel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Interpenetrating polymer networks based on polyol modified castor ...

Indian Academy of Sciences (India)

Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC–PU) and poly[2-hydroxyethylmethacrylate] (PHEMA) were synthesized using benzoyl peroxide as initiator and N,N-methylene bis acrylamide as crosslinker. GC–PU/PHEMA interpenetrating polymer networks were obtained by ...

Effect of enzymatic degradation of chitosan in polyhydroxybutyrate/chitosan/calcium phosphate composites on in vitro osteoblast response.

Science.gov (United States)

Giretova, Maria; Medvecky, Lubomir; Stulajterova, Radoslava; Sopcak, Tibor; Briancin, Jaroslav; Tatarkova, Monika

2016-12-01

Polyhydroxybutyrate/chitosan/calcium phosphate composites are interesting biomaterials for utilization in regenerative medicine and they may by applied in reconstruction of deeper subchondral defects. Insufficient informations were found in recent papers about the influence of lysozyme degradation of chitosan in calcium phosphate/chitosan based composites on in vitro cytotoxicity and proliferation activity of osteoblasts. The effect of enzymatic chitosan degradation on osteoblasts proliferation was studied on composite films in which the porosity of origin 3D scaffolds was eliminated and the surface texture was modified. The significantly enhanced proliferation activity with faster population growth of osteoblasts were found on enzymatically degraded biopolymer composite films with α-tricalcium phosphate and nanohydroxyapatite. No cytotoxicity of composite films prepared from lysozyme degraded scaffolds containing a large fraction of low molecular weight chitosans (LMWC), was revealed after 10 days of cultivation. Contrary to above in the higher cytotoxicity origin untreated nanohydroxyapatite films and porous composite scaffolds. The results showed that the synergistic effect of surface distribution, morphology of nanohydroxyapatite particles, microtopography and the presence of LMWC due to chitosan degradation in composite films were responsible for compensation of the cytotoxicity of nanohydroxyapatite composite films or porous composite scaffolds.

Polyvinylpyrrolidone-based semi-interpenetrating polymer networks as highly selective and chemically stable membranes for all vanadium redox flow batteries

Science.gov (United States)

Zeng, L.; Zhao, T. S.; Wei, L.; Zeng, Y. K.; Zhang, Z. H.

2016-09-01

Vanadium redox flow batteries (VRFBs) with their high flexibility in configuration and operation, as well as long cycle life are competent for the requirement of future energy storage systems. Nevertheless, due to the application of perfluorinated membranes, VRFBs are plagued by not only the severe migration issue of vanadium ions, but also their high cost. Herein, we fabricate semi-interpenetrating polymer networks (SIPNs), consisting of cross-linked polyvinylpyrrolidone (PVP) and polysulfone (PSF), as alternative membranes for VRFBs. It is demonstrated that the PVP-based SIPNs exhibit extremely low vanadium permeabilities, which contribute to the well-established hydrophilic/hydrophobic microstructures and the Donnan exclusion effect. As a result, the coulombic efficiencies of VRFBs with PVP-based SIPNs reach almost 100% at 40 mA cm-2 to 100 mA cm-2; the energy efficiencies are more than 3% higher than those of VRFBs with Nafion 212. More importantly, the PVP-based SIPNs exhibit a superior chemical stability, as demonstrated both by an ex situ immersion test and continuously cycling test. Hence, all the characterizations and performance tests reported here suggest that PVP-based SIPNs are a promising alternative membrane for redox flow batteries to achieve superior cell performance and excellent cycling stability at the fraction of the cost of perfluorinated membranes.

Semi-Degradable Poly(β-amino ester) Networks with Temporally-Controlled Enhancement of Mechanical Properties

Science.gov (United States)

Safranski, David L.; Weiss, Daiana; Clark, J. Brian; Taylor, W.R.; Gall, Ken

2014-01-01

Biodegradable polymers are clinically used in numerous biomedical applications, and classically show a loss in mechanical properties within weeks of implantation. This work demonstrates a new class of semi-degradable polymers that show an increase in mechanical properties through degradation via a controlled shift in a thermal transition. Semi-degradable polymer networks, poly(β-amino ester)-co-methyl methacrylate, were formed from a low glass transition temperature crosslinker, poly(β-amino ester), and high glass transition temperature monomer, methyl methacrylate, which degraded in a manner dependent upon the crosslinker chemical structure. In vitro and in vivo degradation revealed changes in mechanical behavior due to the degradation of the crosslinker from the polymer network. This novel polymer system demonstrates a strategy to temporally control the mechanical behavior of polymers and to enhance the initial performance of smart biomedical devices. PMID:24769113

Enzymatic description of the anhydrofructose pathway of glycogen degradation. I

DEFF Research Database (Denmark)

Yu, Shukun; Refdahl, Charlotte; Lundt, Inge

2004-01-01

The anhydrofructose pathway describes the degradation of glycogen and starch to metabolites via 1,5-anhydro-D-fructose (1,5AnFru). The enzyme catalyzing the first reaction step of this pathway, i.e., a-1,4-glucan lyase (EC 4.2.1.13), has been purified, cloned and characterized from fungi and red...... possessed all enzymes needed for conversion of glycogen to APP, an a-1,4-glucan lyase from this fungus was isolated and partially sequenced. Based on this work, a scheme of the enzymatic description of the anhydrofructose pathway in A. melaloma was proposed. Keywords: Anhydrofructose pathway; Anthracobia...

Semi-degradable poly(β-amino ester) networks with temporally controlled enhancement of mechanical properties.

Science.gov (United States)

Safranski, David L; Weiss, Daiana; Clark, J Brian; Taylor, W Robert; Gall, Ken

2014-08-01

Biodegradable polymers are clinically used in numerous biomedical applications, and classically show a loss of mechanical properties within weeks of implantation. This work demonstrates a new class of semi-degradable polymers that show an increase in mechanical properties through degradation via a controlled shift in a thermal transition. Semi-degradable polymer networks, poly(β-amino ester)-co-methyl methacrylate, were formed from a low glass transition temperature crosslinker, poly(β-amino ester), and high glass transition temperature monomer, methyl methacrylate, which degraded in a manner dependent upon the crosslinker chemical structure. In vitro and in vivo degradation revealed changes in mechanical behavior due to the degradation of the crosslinker from the polymer network. This novel polymer system demonstrates a strategy to temporally control the mechanical behavior of polymers and to enhance the initial performance of smart biomedical devices. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Soft silicone based interpenetrating networks as materials for actuators

DEFF Research Database (Denmark)

Yu, Liyun; Gonzalez, Lidia; Hvilsted, Søren

2014-01-01

A new approach based on silicone interpenetrating networks with orthogonal chemistries has been investigated with focus on developing soft and flexible elastomers with high energy densities and small viscous losses. The interpenetrating networks are made as simple two pot mixtures...... as for the commercial available silylation based elastomers such as Elastosil RT625. The resulting interpenetrating networks are formulated to be softer than RT625 to increase the actuation caused when applying a voltage due to their softness combined with the significantly higher permittivity than the pure silicone...

Surface Plasmon Resonance Imaging of the Enzymatic Degradation of Cellulose Microfibrils

Science.gov (United States)

Reiter, Kyle; Raegen, Adam; Clarke, Anthony; Lipkowski, Jacek; Dutcher, John

2012-02-01

As the largest component of biomass on Earth, cellulose represents a significant potential energy reservoir. Enzymatic hydrolysis of cellulose into fermentable sugars, an integral step in the production of biofuel, is a challenging problem on an industrial scale. More efficient conversion processes may be developed by an increased understanding of the action of the cellulolytic enzymes involved in cellulose degradation. We have used our recently developed quantitative, angle-scanning surface plasmon resonance imaging (SPRi) device to study the degradation of cellulose microfibrils upon exposure to cellulosic enzymes. In particular, we have studied the action of individual enzymes, and combinations of enzymes, from the Hypocrea Jecorina cellulase system on heterogeneous, industrially-relevant cellulose substrates. This has allowed us to define a characteristic time of action for the enzymes for different degrees of surface coverage of the cellulose microfibrils.

Biocatalytic degradation of pharmaceuticals, personal care products, industrial chemicals, steroid hormones and pesticides in a membrane distillation-enzymatic bioreactor.

Science.gov (United States)

Asif, Muhammad B; Hai, Faisal I; Kang, Jinguo; van de Merwe, Jason P; Leusch, Frederic D L; Price, William E; Nghiem, Long D

2018-01-01

Laccase-catalyzed degradation of a broad spectrum of trace organic contaminants (TrOCs) by a membrane distillation (MD)-enzymatic membrane bioreactor (EMBR) was investigated. The MD component effectively retained TrOCs (94-99%) in the EMBR, facilitating their continuous biocatalytic degradation. Notably, the extent of TrOC degradation was strongly influenced by their molecular properties. A significant degradation (above 90%) of TrOCs containing strong electron donating functional groups (e.g., hydroxyl and amine groups) was achieved, while a moderate removal was observed for TrOCs containing electron withdrawing functional groups (e.g., amide and halogen groups). Separate addition of two redox-mediators, namely syringaldehyde and violuric acid, further improved TrOC degradation by laccase. However, a mixture of both showed a reduced performance for a few pharmaceuticals such as primidone, carbamazepine and ibuprofen. Mediator addition increased the toxicity of the media in the enzymatic bioreactor, but the membrane permeate (i.e., final effluent) was non-toxic, suggesting an added advantage of coupling MD with EMBR. Copyright © 2017 Elsevier Ltd. All rights reserved.

Implications Enzymatic Degradation of the Endothelial Glycocalyx on the Microvascular Hemodynamics and the Arteriolar Red Cell Free Layer of the Rat Cremaster Muscle

Directory of Open Access Journals (Sweden)

Ozlem Yalcin

2018-03-01

Full Text Available The endothelial glycocalyx is a complex network of glycoproteins, proteoglycans, and glycosaminoglycans; it lines the vascular endothelial cells facing the lumen of blood vessels forming the endothelial glycocalyx layer (EGL. This study aims to investigate the microvascular hemodynamics implications of the EGL by quantifying changes in blood flow hydrodynamics post-enzymatic degradation of the glycocalyx layer. High-speed intravital microscopy videos of small arteries (around 35 μm of the rat cremaster muscle were recorded at various time points after enzymatic degradation of the EGL. The thickness of the cell free layer (CFL, blood flow velocity profiles, and volumetric flow rates were quantified. Hydrodynamic effects of the presence of the EGL were observed in the differences between the thickness of CFL in microvessels with an intact EGL and glass tubes of similar diameters. Maximal changes in the thickness of CFL were observed 40 min post-enzymatic degradation of the EGL. Analysis of the frequency distribution of the thickness of CFL allows for estimation of the thickness of the endothelial surface layer (ESL, the plasma layer, and the glycocalyx. Peak flow, maximum velocity, and mean velocity were found to statistically increase by 24, 27, and 25%, respectively, after enzymatic degradation of the glycocalyx. The change in peak-to-peak maximum velocity and mean velocity were found to statistically increase by 39 and 32%, respectively, after 40 min post-enzymatic degradation of the EGL. The bluntness of blood flow velocity profiles was found to be reduced post-degradation of the EGL, as the exclusion volume occupied by the EGL increased the effective volume impermeable to RBCs in microvessels. This study presents the effects of the EGL on microvascular hemodynamics. Enzymatic degradation of the EGL resulted in a decrease in the thickness of CFL, an increase in blood velocity, blood flow, and decrease of the bluntness of the blood flow

Implications Enzymatic Degradation of the Endothelial Glycocalyx on the Microvascular Hemodynamics and the Arteriolar Red Cell Free Layer of the Rat Cremaster Muscle.

Science.gov (United States)

Yalcin, Ozlem; Jani, Vivek P; Johnson, Paul C; Cabrales, Pedro

2018-01-01

The endothelial glycocalyx is a complex network of glycoproteins, proteoglycans, and glycosaminoglycans; it lines the vascular endothelial cells facing the lumen of blood vessels forming the endothelial glycocalyx layer (EGL). This study aims to investigate the microvascular hemodynamics implications of the EGL by quantifying changes in blood flow hydrodynamics post-enzymatic degradation of the glycocalyx layer. High-speed intravital microscopy videos of small arteries (around 35 μm) of the rat cremaster muscle were recorded at various time points after enzymatic degradation of the EGL. The thickness of the cell free layer (CFL), blood flow velocity profiles, and volumetric flow rates were quantified. Hydrodynamic effects of the presence of the EGL were observed in the differences between the thickness of CFL in microvessels with an intact EGL and glass tubes of similar diameters. Maximal changes in the thickness of CFL were observed 40 min post-enzymatic degradation of the EGL. Analysis of the frequency distribution of the thickness of CFL allows for estimation of the thickness of the endothelial surface layer (ESL), the plasma layer, and the glycocalyx. Peak flow, maximum velocity, and mean velocity were found to statistically increase by 24, 27, and 25%, respectively, after enzymatic degradation of the glycocalyx. The change in peak-to-peak maximum velocity and mean velocity were found to statistically increase by 39 and 32%, respectively, after 40 min post-enzymatic degradation of the EGL. The bluntness of blood flow velocity profiles was found to be reduced post-degradation of the EGL, as the exclusion volume occupied by the EGL increased the effective volume impermeable to RBCs in microvessels. This study presents the effects of the EGL on microvascular hemodynamics. Enzymatic degradation of the EGL resulted in a decrease in the thickness of CFL, an increase in blood velocity, blood flow, and decrease of the bluntness of the blood flow velocity profile in

Enzymatic Phorbol Esters Degradation using the Germinated Jatropha Curcas Seed Lipase as Biocatalyst: Optimization Process Conditions by Response Surface Methodology

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Avita Kusuma Wardhani

2016-10-01

Full Text Available Utilization of Jatropha curcas seed cake is limited by the presence of phorbol esters (PE, which are the main toxic compound and heat stable. The objective of this research was to optimize the reaction conditions of the enzymatic PE degradation of the defatted Jatropha curcas seed cake (DJSC using the acetone-dried lipase from the germinated Jatropha curcas seeds as a biocatalyst. Response Surface Methodology (RSM using three-factors-three-levels Box-Behnken design was used to evaluate the effects of the reaction time, the ratio of buffer volume to DJSC, and the ratio of enzyme to DJSC on PE degradation. The results showed that the optimum conditions of PE degradation were 29.33 h, 51.11 : 6 (mL/g, and 30.10 : 5 (U/g cake for the reaction time, the ratio of buffer volume to DJSC, and the ratio of enzyme to DJSC, respectively. The predicted degradation of PE was 98.96% and not significantly different with the validated data of PE degradation. PE content was 0.035 mg/g, in which it was lower than PE in non-toxic Jatropha seeds. The results indicated that enzymatic degradation of PE might be a promising method for degradation of PE.  Copyright © 2016 BCREC GROUP. All rights reserved Received: 22nd December 2015; Revised: 1st April 2016; Accepted: 14th April 2016 How to Cite: Wardhani, A.K., Hidayat, C., Hastuti, P. (2016. Enzymatic Phorbol Esters Degradation using the Germinated Jatropha Curcas Seed Lipase as Biocatalyst: Optimization Process Conditions by Response Surface Methodology. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 346-353 (doi:10.9767/bcrec.11.3.574.346-353 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.574.346-353

Formation and enzymatic degradation of poly-l-arginine/fucoidan multilayer films.

Science.gov (United States)

Webber, Jessie L; Benbow, Natalie L; Krasowska, Marta; Beattie, David A

2017-11-01

A polyelectrolyte multilayer (PEM) system based on biopolymers has been constructed and studied in its formation and enzymatic breakdown. The multilayer is composed of fucoidan (a proven antimicrobial/anti-inflammatory seaweed-based polysaccharide) and poly-l-arginine (a polypeptide that can be readily degraded with trypsin to yield arginine, a known NO donor), thus making the multilayer a potential dual action surface treatment for wound dressings. Studies on the formation of the multilayer revealed that the film built-up in the expected stepwise manner with consistent reversal of the zeta potential upon the adsorption of each subsequent polyion. The completed film (8 bilayers) was seen to have low hydration (30% water), as determined by H 2 O/D 2 O solvent replacement studies using the quartz crystal microbalance, with an adsorbed mass (without hydration water) of approx. 4.8μgcm -2 , as determined by quantitative attenuated total reflectance Fourier transform infrared (ATR FTIR) spectroscopy. The enzymatic breakdown of the film in response to exposure to trypsin was also investigated, and the film was seen to release both polymers over time, with a projected complete film removal period of approximately 24h. Critically, this information was determined using ATR FTIR spectroscopy experiments, which allowed unambiguous deconvolution of the removal rates of the two polyions, which is information that cannot be obtained from other methodologies used to study enzymatic breakdown of surface films. Copyright © 2017 Elsevier B.V. All rights reserved.

A 3-D Model of a Perennial Ryegrass Primary Cell Wall and Its Enzymatic Degradation

Directory of Open Access Journals (Sweden)

Indrakumar Vetharaniam

2014-05-01

Full Text Available We have developed a novel 3-D, agent-based model of cell-wall digestion to improve our understanding of ruminal cell-wall digestion. It offers a capability to study cell walls and their enzymatic modification, by providing a representation of cellulose microfibrils and non-cellulosic polysaccharides and by simulating their spatial and catalytic interactions with enzymes. One can vary cell-wall composition and the types and numbers of enzyme molecules, allowing the model to be applied to a range of systems where cell walls are degraded and to the modification of cell walls by endogenous enzymes. As a proof of principle, we have modelled the wall of a mesophyll cell from the leaf of perennial ryegrass and then simulated its enzymatic degradation. This is a primary, non-lignified cell wall and the model includes cellulose, hemicelluloses (glucuronoarabinoxylans, 1,3;1,4-β-glucans, and xyloglucans and pectin. These polymers are represented at the level of constituent monosaccharides, and assembled to form a 3-D, meso-scale representation of the molecular structure of the cell wall. The composition of the cell wall can be parameterised to represent different walls in different cell types and taxa. The model can contain arbitrary combinations of different enzymes. It simulates their random diffusion through the polymer networks taking collisions into account, allowing steric hindrance from cell-wall polymers to be modelled. Steric considerations are included when target bonds are encountered, and breakdown products resulting from enzymatic activity are predicted.

Simulation of the infiltration process of a ceramic open-pore body with a metal alloy in semi-solid state to design the manufacturing of interpenetrating phase composites

Science.gov (United States)

Schomer, Laura; Liewald, Mathias; Riedmüller, Kim Rouven

2018-05-01

Metal-ceramic Interpenetrating Phase Composites (IPC) belong to a special subcategory of composite materials and reveal enhanced properties compared to conventional composite materials. Currently, IPC are produced by infiltration of a ceramic open-pore body with liquid metal applying high pressure and I or high temperature to avoid residual porosity. However, these IPC are not able to gain their complete potential, because of structural damages and interface reactions occurring during the manufacturing process. Compared to this, the manufacturing of IPC using the semi-solid forming technology offers great perspectives due to relative low processing temperatures and reduced mechanical pressure. In this context, this paper is focusing on numerical investigations conducted by using the FLOW-3D software for gaining a deeper understanding of the infiltration of open-pore bodies with semi-solid materials. For flow simulation analysis, a geometric model and different porous media drag models have been used. They have been adjusted and compared to get a precise description of the infiltration process. Based on these fundamental numerical investigations, this paper also shows numerical investigations that were used for basically designing a semi-solid forming tool. Thereby, the development of the flow front and the pressure during the infiltration represent the basis of the evaluation. The use of an open and closed tool cavity combined with various geometries of the upper die shows different results relating to these evaluation arguments. Furthermore, different overflows were designed and its effects on the pressure at the end of the infiltration process were investigated. Thus, this paper provides a general guideline for a tool design for manufacturing of metal-ceramic IPC using semi-solid forming.

Enhancement of Lactobacillus reuteri KUB-AC5 survival in broiler gastrointestinal tract by microencapsulation with alginate-chitosan semi-interpenetrating polymer networks.

Science.gov (United States)

Rodklongtan, A; La-ongkham, O; Nitisinprasert, S; Chitprasert, P

2014-07-01

To evaluate an alginate-chitosan microcapsule for an intestinal probiotic delivery system for broilers. Lactobacillus reuteri KUB-AC5 was successfully microencapsulated with alginate and chitosan mixtures using an emulsion cross-linking method with high microencapsulation efficiency. Scanning electron microscopy revealed a large number of the bacteria entrapped in the semi-interpenetrating network. The microcapsule effectively protected the cells against strong acids. The in vitro study showed that the 8 log CFU g(-1) was released at the jejunum and ileum. For the in vivo study, the number of probiotics was detected by a polymerase chain reaction-based random amplified polymorphic DNA technique. From provision of 10 log CFU, cell numbers of 5-8 log CFU were observed in the intestine. The alginate-chitosan microcapsule can serve as a potential intestine-targeted probiotic delivery system. To the best of our knowledge, this is the first comparison study of the in vitro and in vivo gastrointestinal profiles of microencapsulated probiotics used as feed additives for broilers. This study reveals the similarities and differences of the in vitro and in vivo probiotic profiles and provides convincing evidence of the potential use of the alginate-chitosan microcapsule as a probiotic delivery system. © 2014 The Society for Applied Microbiology.

Effects of thermo-chemical pretreatment plus microbial fermentation and enzymatic hydrolysis on saccharification and lignocellulose degradation of corn straw.

Science.gov (United States)

Wang, Ping; Chang, Juan; Yin, Qingqiang; Wang, Erzhu; Zhu, Qun; Song, Andong; Lu, Fushan

2015-10-01

In order to increase corn straw degradation, the straw was kept in the combined solution of 15% (w/w) lime supernatant and 2% (w/w) sodium hydroxide with liquid-to-solid ratio of 13:1 (mL/g) at 83.92°C for 6h; and then added with 3% (v/v) H2O2 for reaction at 50°C for 2h; finally cellulase (32.3 FPU/g dry matter) and xylanase (550 U/g dry matter) was added to keep at 50°C for 48 h. The maximal reducing sugars yield (348.77 mg/g) was increased by 126.42% (Pcellulose, hemicellulose and lignin in pretreated corn straw with enzymatic hydrolysis were increased by 40.08%, 45.71% and 52.01%, compared with the native corn straw with enzymatic hydrolysis (P<0.05). The following study indicated that the combined microbial fermentation and enzymatic hydrolysis could further increase straw degradation and reducing sugar yield (442.85 mg/g, P<0.05). Copyright © 2015 Elsevier Ltd. All rights reserved.

Soil organic matter degradation and enzymatic profiles of intertidal and subaqueous soils

Science.gov (United States)

Ferronato, Chiara; Marinari, Sara; Bello, Diana; Vianello, Gilmo; Trasar-Cepeda, Carmen; Vittori Antisari, Livia

2017-04-01

The interest on intertidal and subaqueous soils has recently arisen because of the climate changes forecasts. The preservation of these habitats represents an important challenge for the future of humanity, because these systems represent an important global C sink since soil organic matter (SOM) on intertidal and subaqueous soils undergoes very slow degradation rates due to oxygen limitation. Publications on SOM cycle in saltmarshes are very scarce because of the difficulties involved on those studies i.e. the interaction of many abiotic and biotic factors (e.g., redox changes, water and bio-turbation processes, etc) and stressors (e.g., salinity and anoxia). However, saltmarshes constitute an unique natural system to observe the influence of anoxic conditions on SOM degradation, because the tide fluctuations on the soil surface allow the formation of provisionally or permanently submerged soils. With the aim to investigate the quality of SOM in subaqueous soils, triplicates of subaqueous soils (SASs), intertidal soils (ITSs) and terrestrial soils (TESs) were collected in the saltmarshes of the Baiona Lagoon (Northern Italy) and classified according to their pedogenetic horizons. The SOM quality on each soil horizon was investigated by quantifying SOM, total and water-soluble organic carbon (TOC, WSC) and microbial biomass carbon (MBC). Given the contribution of soil enzymes to the degradation of SOM, some enzymatic assays were also performed. Thereafter, soil classification and humus morpho-functional classification were used to join together similar soil profiles to facilitate the description and discussion of results. Soils were ranked as Aquent or Wassent Entisols, with an A/AC/C pedosequence. SOM, TOC and MBC were statistically higher in A than in AC and C horizons. Among the A horizons, ITSs were those showing the highest values for these parameters (11% TOC, 1.6 mg kg-1 MBC, 0.9 mg kg-1 WSC). These results, combined with the morpho-functional classification

Monitoring of the Enzymatically Catalyzed Degradation of Biodegradable Polymers by Means of Capacitive Field-Effect Sensors.

Science.gov (United States)

Schusser, Sebastian; Krischer, Maximilian; Bäcker, Matthias; Poghossian, Arshak; Wagner, Patrick; Schöning, Michael J

2015-07-07

Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(D,L-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.

A non-equilibrium thermodynamic model for tumor extracellular matrix with enzymatic degradation

Science.gov (United States)

Xue, Shi-Lei; Li, Bo; Feng, Xi-Qiao; Gao, Huajian

2017-07-01

The extracellular matrix (ECM) of a solid tumor not only affords scaffolding to support tumor architecture and integrity but also plays an essential role in tumor growth, invasion, metastasis, and therapeutics. In this paper, a non-equilibrium thermodynamic theory is established to study the chemo-mechanical behaviors of tumor ECM, which is modeled as a poroelastic polyelectrolyte consisting of a collagen network and proteoglycans. By using the principle of maximum energy dissipation rate, we deduce a set of governing equations for drug transport and mechanosensitive enzymatic degradation in ECM. The results reveal that osmosis is primarily responsible for the compression resistance of ECM. It is suggested that a well-designed ECM degradation can effectively modify the tumor microenvironment for improved efficiency of cancer therapy. The theoretical predictions show a good agreement with relevant experimental observations. This study aimed to deepen our understanding of tumor ECM may be conducive to novel anticancer strategies.

Enzymatic cyanide degradation by cell-free extract of Rhodococcus UKMP-5M.

Science.gov (United States)

Nallapan Maniyam, Maegala; Sjahrir, Fridelina; Latif Ibrahim, Abdul; Cass, Anthony E G

2015-01-01

The cell-free extract of locally isolated Rhodococcus UKMP-5M strain was used as an alternative to develop greener and cost effective cyanide removal technology. The present study aims to assess the viability of the cell-free extract to detoxify high concentrations of cyanide which is measured through the monitoring of protein concentration and specific cyanide-degrading activity. When cyanide-grown cells were subjected to grinding in liquid nitrogen which is relatively an inexpressive and fast cell disruption method, highest cyanide-degrading activity of 0.63 mM min(-1) mg(-1) protein was obtained in comparison to enzymatic lysis and agitation with fine glass beads. The cell-free extracts managed to degrade 80% of 20 mM KCN within 80 min and the rate of cyanide consumption increased linearly as the concentration of protein was raised. In both cases, the addition of co-factor was not required which proved to be advantageous economically. The successful formation of ammonia and formate as endproducts indicated that the degradation of cyanide by Rhodococcus UKMP-5M proceeded via the activity of cyanidase and the resulting non-toxic products are safe for disposal into the environment. Further verification with SDS-PAGE revealed that the molecular weight of the active enzyme was estimated to be 38 kDa, which is consistent with previously reported cyanidases. Thus, the utilization of cell-free extracts as an alternative to live microbial in cyanide degradation offers numerous advantageous such as the potential to tolerate and degrade higher concentration of cyanide and total reduction in the overall cost of operation since the requirement for nutrient support is irrelevant.

Human-Induced Vegetation Degradation in a Semi-Arid Rangeland

Science.gov (United States)

Jackson, Hasan

Current assessments of anthropogenic land degradation and its impact on vegetation at regional scales are prone to large uncertainties due to the lack of an objective, transferable, spatially and temporally explicit measure of land degradation. These uncertainties have resulted in contradictory estimates of degradation extent and severity and the role of human activities. The uncertainties limit the ability to assess the effects on the biophysical environment and effectiveness of past, current, and future policies of land use. The overall objective of the dissertation is to assess degradation in a semi-arid region at a regional scale where the process of anthropogenic land degradation is evident. Net primary productivity (NPP) is used as the primary indicator to measure degradation. It is hypothesized that land degradation resulting from human factors on the landscape irreversibly reduces NPP below the potential set by environmental conditions. It is also hypothesized that resulting reductions in NPP are distinguishable from natural, spatial and temporal, variability in NPP. The specific goals of the dissertation are to (1) identify the extent and severity of degradation using productivity as the primary surrogate, (2) compare the degradation of productivity to other known mechanisms of degradation, and (3) relate the expression of degradation to components of vegetation and varying environmental conditions. This dissertation employed the Local NPP Scaling (LNS) approach to identify patterns of anthropogenic degradation of NPP in the Burdekin Dry Tropics (BDT) region of Queensland (14 million hectares), Australia from 2000 to 2013. The method started with land classification based on the environmental factors presumed to control NPP to group pixels having similar potential NPP. Then, satellite remotely sensing data were used to compare actual NPP with its potential. The difference, in units of mass of carbon fixed in NPP per unit area per monitoring interval and

Synthesis and characterization of semi-IPNs based on PVP and PLLA; Sintese e caracterizacao de semi-IPNs envolvendo os homopolimeros PVP e PLLA

Energy Technology Data Exchange (ETDEWEB)

Camilo, A.P.R.; Mano, V., E-mail: mano@ufsj.edu.b [Universidade Federal de Sao Joao del Rei (UFSJ), MG (Brazil). Dept. de Ciencias Naturais; Felisberti, M.I. [Universidade Estadual de Campinas (IQ/UNICAMP), SP (Brazil). Inst. de Quimica

2010-07-01

The specific interest in the synthesis of semi-IPNs based on PLLA and PVP homopolymers due to the fact these are biodegradable and biocompatible, which allows us to infer applications in the medical field as sutures, implants, matrices for controlled release of drugs etc. The objective was to prepare a multicomponent material amphiphile in the form of semi-interpenetrating polymer networks, based on poly (L-lactide), PLLA, hydrophobic homopolymer, and poly (vinylpyrrolidone), PVP, hydrophilic component. The preparation of semi-IPN combined the polymerization and crosslinking of N-vinylpyrrolidone in the presence of poly (L-lactide). The products were characterized by spectroscopic and thermal methods. (author)

Hydrological Response of Semi-arid Degraded Catchments in Tigray, Northern Ethiopia

Science.gov (United States)

Teka, Daniel; Van Wesemael, Bas; Vanacker, Veerle; Hallet, Vincent

2013-04-01

To address water scarcity in the arid and semi-arid part of developing countries, accurate estimation of surface runoff is an essential task. In semi-arid catchments runoff data are scarce and therefore runoff estimation using hydrological models becomes an alternative. This research was initiated in order to characterize runoff response of semi-arid catchments in Tigray, North Ethiopia to evaluate SCS-CN for various catchments. Ten sub-catchments were selected in different river basins and rainfall and runoff were measured with automatic hydro-monitoring equipments for 2-3 years. The Curve Number was estimated for each Hydrological Response Unit (HRU) in the sub-catchments and runoff was modeled using the SCS-CN method at λ = 0.05 and λ = 0.20. The result showed a significant difference between the two abstraction ratios (P =0.05, df = 1, n= 132) and reasonable good result was obtained for predicted runoff at λ = 0.05 (NSE = -0.69; PBIAS = 18.1%). When using the CN values from literature runoff was overestimated compared to the measured value (e= -11.53). This research showed the importance of using measured runoff data to characterize semi-arid catchments and accurately estimate the scarce water resource. Key words: Hydrological response, rainfall-runoff, degraded environments, semi-arid, Ethiopia, Tigray

Interpenetrating networks of two conducting polymers

DEFF Research Database (Denmark)

Winther-Jensen, Bjørn; West, Keld

2005-01-01

Interpenetrating networks (IPNs) of two conjugated polymers are prepared by a combination of a chemical oxidation step and a vapour phase polymerisation step on non-conducting surfaces. In this work ferric tosylate was used as the oxidant as it gives very smooth and homogeneous coatings, and beca......Interpenetrating networks (IPNs) of two conjugated polymers are prepared by a combination of a chemical oxidation step and a vapour phase polymerisation step on non-conducting surfaces. In this work ferric tosylate was used as the oxidant as it gives very smooth and homogeneous coatings......, and because its reaction products can be removed efficiently after the formation of the composite. Several combinations of polymers are demonstrated, and the versatility of the proposed method allows extensions to a wide range of conjugated polymers. The IPNs show optical and electrochemical characteristics......, which are sums of the characteristics from the participating conducting polymers....

Impact of vent pipe diameter on characteristics of waste degradation in semi-aerobic bioreactor landfill.

Science.gov (United States)

Jiang, Guobin; Liu, Dan; Chen, Weiming; Ye, Zhicheng; Liu, Hong; Li, Qibin

2017-10-01

The evolution mechanism of a vent pipe diameter on a waste-stabilization process in semi-aerobic bioreactor landfills was analyzed from the organic-matter concentration, biodegradability, spectral characteristics of dissolved organic matter, correlations and principal-component analysis. Waste samples were collected at different distances from the vent pipe and from different landfill layers in semi-aerobic bioreactor landfills with different vent pipe diameters. An increase in vent pipe diameter favored waste degradation. Waste degradation in landfills can be promoted slightly when the vent pipe diameter increases from 25 to 50 mm. It could be promoted significantly when the vent pipe diameter was increased to 75 mm. The vent pipe diameter is important in waste degradation in the middle layer of landfills. The dissolved organic matter in the waste is composed mainly of long-wave humus (humin), short-wave humus (fulvic acid) and tryptophan. The humification levels of the waste that was located at the center of vent pipes with 25-, 50- and 75-mm diameters were 2.2682, 4.0520 and 7.6419 Raman units, respectively. The appropriate vent pipe diameter for semi-aerobic bioreactor landfills with an 800-mm diameter was 75 mm. The effect of different vent pipe diameters on the degree of waste stabilization is reflected by two main components. Component 1 is related mainly to the content of fulvic acid, biologically degradable material and organic matter. Component 2 is related mainly to the content of tryptophan and humin from the higher vascular plants.

Removal of antibiotics in wastewater by enzymatic treatment with fungal laccase - Degradation of compounds does not always eliminate toxicity.

Science.gov (United States)

Becker, Dennis; Varela Della Giustina, Saulo; Rodriguez-Mozaz, Sara; Schoevaart, Rob; Barceló, Damià; de Cazes, Matthias; Belleville, Marie-Pierre; Sanchez-Marcano, José; de Gunzburg, Jean; Couillerot, Olivier; Völker, Johannes; Oehlmann, Jörg; Wagner, Martin

2016-11-01

In this study, the performance of immobilised laccase (Trametes versicolor) was investigated in combination with the mediator syringaldehyde (SYR) in removing a mixture of 38 antibiotics in an enzymatic membrane reactor (EMR). Antibiotics were spiked in osmosed water at concentrations of 10μg·L(-1) each. Laccase without mediator did not reduce the load of antibiotics significantly. The addition of SYR enhanced the removal: out of the 38 antibiotics, 32 were degraded by >50% after 24h. In addition to chemical analysis, the samples' toxicity was evaluated in two bioassays (a growth inhibition assay and the Microtox assay). Here, the addition of SYR resulted in a time-dependent increase of toxicity in both bioassays. In cooperation with SYR, laccase effectively removes a broad range of antibiotics. However, this enhanced degradation induces unspecific toxicity. If this issue is resolved, enzymatic treatment may be a valuable addition to existing water treatment technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and characterization of semi-IPNs based on PVP and PLLA

International Nuclear Information System (INIS)

Camilo, A.P.R.; Mano, V.; Felisberti, M.I.

2010-01-01

The specific interest in the synthesis of semi-IPNs based on PLLA and PVP homopolymers due to the fact these are biodegradable and biocompatible, which allows us to infer applications in the medical field as sutures, implants, matrices for controlled release of drugs etc. The objective was to prepare a multicomponent material amphiphile in the form of semi-interpenetrating polymer networks, based on poly (L-lactide), PLLA, hydrophobic homopolymer, and poly (vinylpyrrolidone), PVP, hydrophilic component. The preparation of semi-IPN combined the polymerization and crosslinking of N-vinylpyrrolidone in the presence of poly (L-lactide). The products were characterized by spectroscopic and thermal methods. (author)

Implicit multi-fluid simulation of interpenetrating plasmas

International Nuclear Information System (INIS)

Rambo, P.W.; Denavit, J.

1992-01-01

A one dimensional simulation code for interpenetrating multi-component plasmas is presented. Separate fluid equations for multiple species and the Poisson equation for the electric field are solved implicitly to allow stable accurate solutions over a wide range of the time scale parameters ω p Δt and ν c Δt (ω p is the plasma frequency, ν c a typical collision frequency and Δt the time step). In regions where ω p Δt c Δt p Δt >>1 and/or ν c Δt>>1, the ambipolar and/or diffusion models are recovered. In regions of low collisionality, particles may be created and deleted which are followed using particle and cell techniques combined with scatter and drag due to collisions with the fluids. Applications of this code to interpenetrating laser generated plasmas are presented

Lignin from hydrothermally pretreated grass biomass retards enzymatic cellulose degradation by acting as a physical barrier rather than by inducing nonproductive adsorption of enzymes.

Science.gov (United States)

Djajadi, Demi T; Jensen, Mads M; Oliveira, Marlene; Jensen, Anders; Thygesen, Lisbeth G; Pinelo, Manuel; Glasius, Marianne; Jørgensen, Henning; Meyer, Anne S

2018-01-01

Lignin is known to hinder efficient enzymatic conversion of lignocellulose in biorefining processes. In particular, nonproductive adsorption of cellulases onto lignin is considered a key mechanism to explain how lignin retards enzymatic cellulose conversion in extended reactions. Lignin-rich residues (LRRs) were prepared via extensive enzymatic cellulose degradation of corn stover ( Zea mays subsp. mays L.), Miscanthus  ×  giganteus stalks (MS) and wheat straw ( Triticum aestivum L.) (WS) samples that each had been hydrothermally pretreated at three severity factors (log R 0 ) of 3.65, 3.83 and 3.97. The LRRs had different residual carbohydrate levels-the highest in MS; the lowest in WS. The residual carbohydrate was not traceable at the surface of the LRRs particles by ATR-FTIR analysis. The chemical properties of the lignin in the LRRs varied across the three types of biomass, but monolignols composition was not affected by the severity factor. When pure cellulose was added to a mixture of LRRs and a commercial cellulolytic enzyme preparation, the rate and extent of glucose release were unaffected by the presence of LRRs regardless of biomass type and severity factor, despite adsorption of the enzymes to the LRRs. Since the surface of the LRRs particles were covered by lignin, the data suggest that the retardation of enzymatic cellulose degradation during extended reaction on lignocellulosic substrates is due to physical blockage of the access of enzymes to the cellulose caused by the gradual accumulation of lignin at the surface of the biomass particles rather than by nonproductive enzyme adsorption. The study suggests that lignin from hydrothermally pretreated grass biomass retards enzymatic cellulose degradation by acting as a physical barrier blocking the access of enzymes to cellulose rather than by inducing retardation through nonproductive adsorption of enzymes.

Synthesis and Properties of IPN Hydrogels Based on Konjac Glucomannan and Poly(acrylic acid)

Institute of Scientific and Technical Information of China (English)

Bing LIU; Zhi Lan LIU; Ren Xi ZHUO

2006-01-01

Novel interpenetrating polymer network (IPN) hydrogels based on konjac glucomannan (KGM) and poly(acrylic acid) (PAA) were prepared by polymerization and cross-linking of acrylic acid (AA) in the pre-fabricated KGM gel. The IPN gel was analyzed by FT-IR. The studies on the equilibrium swelling ratio of IPN hydrogels revealed their sensitive response to environmental pH value. The results of in vitro degradation showed that the IPN hydrogels retain the enzymatic degradation character of KGM.

Effect of sub- and supercritical water treatments on the physicochemical properties of crab shell chitin and its enzymatic degradation.

Science.gov (United States)

Osada, Mitsumasa; Miura, Chika; Nakagawa, Yuko S; Kaihara, Mikio; Nikaido, Mitsuru; Totani, Kazuhide

2015-12-10

This study examined the effects of sub- and supercritical water pretreatments on the physicochemical properties of crab shell α-chitin and its enzymatic degradation to obtain N,N'-diacetylchitobiose (GlcNAc)2. Following sub- and supercritical water pretreatments, the protein in the crab shell was removed and the residue of crab shell contained α-chitin and CaCO3. Prolonged pretreatment led to α-chitin decomposition. The reaction of pure α-chitin in sub- and supercritical water pretreatments was investigated separately; we observed lower mean molecular weight and weaker hydrogen bonds compared with untreated α-chitin. (GlcNAc)2 yields from enzymatic degradation of subcritical (350 °C, 7 min) and supercritical water (400 °C, 2.5 min) pretreated crab shell were 8% and 6%, compared with 0% without any pretreatment. This study shows that sub- and supercritical water pretreatments of crab shell provide to an alternative method to the use of acid and base for decalcification and deproteinization of crab shell required for (GlcNAc)2 production. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enzymatically and reductively degradable α-amino acid-based poly(ester amide)s: Synthesis, cell compatibility, and intracellular anticancer drug delivery

NARCIS (Netherlands)

Sun, H.; Cheng, Ru; Deng, Chao; Meng, Fenghua; Dias, Aylvin A.; Hendriks, Marc; Feijen, Jan; Zhong, Zhiyuan

2015-01-01

A novel and versatile family of enzymatically and reductively degradable α-amino acid-based poly(ester amide)s (SS-PEAs) were developed from solution polycondensation of disulfide-containing di-p-toluenesulfonic acid salts of bis-l-phenylalanine diesters (SS-Phe-2TsOH) with di-p-nitrophenyl adipate

Influence of Aloe vera on water absorption and enzymatic in vitro degradation of alginate hydrogel films.

Science.gov (United States)

Pereira, Rúben F; Carvalho, Anabela; Gil, M H; Mendes, Ausenda; Bártolo, Paulo J

2013-10-15

This study investigates the influence of Aloe vera on water absorption and the in vitro degradation rate of Aloe vera-Ca-alginate hydrogel films, for wound healing and drug delivery applications. The influence of A. vera content (5%, 15% and 25%, v/v) on water absorption was evaluated by the incubation of the films into a 0.1 M HCl solution (pH 1.0), acetate buffer (pH 5.5) and simulated body fluid solution (pH 7.4) during 24h. Results show that the water absorption is significantly higher for films containing high A. vera contents (15% and 25%), while no significant differences are observed between the alginate neat film and the film with 5% of A. vera. The in vitro enzymatic degradation tests indicate that an increase in the A. vera content significantly enhances the degradation rate of the films. Control films, incubated in a simulated body fluid solution without enzymes, are resistant to the hydrolytic degradation, exhibiting reduced weight loss and maintaining its structural integrity. Results also show that the water absorption and the in vitro degradation rate of the films can be tailored by changing the A. vera content. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ion conducting interpenetrated lattices for lithium generators; Reseaux interpenetres conducteurs ioniques pour generateurs au lithium

Energy Technology Data Exchange (ETDEWEB)

Grosz, M.; Boileau, S. [College de France, 75 - Paris (France); Guegan, P.; Cheradame, H. [Centre National de la Recherche Scientifique (CNRS), 94 - Thiais (France). LPCB; Deshayes, A. [CNET, 92 - Issy-les-Moulineaux (France)

1996-12-31

Interpenetrated lattices (IPL) are combinations of reticulated polymers linked together by permanent crisscross. This structure is well-adapted to combined highly incompatible pairs of polymers. The in-situ sequential method has been applied successfully to the synthesis of ethylene poly-oxides / poly-siloxanes IPLs. The results concerning the preparation of such lattices and their behaviour as solid polymer electrolytes are presented in this paper. (J.S.) 24 refs.

Ion conducting interpenetrated lattices for lithium generators; Reseaux interpenetres conducteurs ioniques pour generateurs au lithium

Energy Technology Data Exchange (ETDEWEB)

Grosz, M; Boileau, S [College de France, 75 - Paris (France); Guegan, P; Cheradame, H [Centre National de la Recherche Scientifique (CNRS), 94 - Thiais (France). LPCB; Deshayes, A [CNET, 92 - Issy-les-Moulineaux (France)

1997-12-31

Interpenetrated lattices (IPL) are combinations of reticulated polymers linked together by permanent crisscross. This structure is well-adapted to combined highly incompatible pairs of polymers. The in-situ sequential method has been applied successfully to the synthesis of ethylene poly-oxides / poly-siloxanes IPLs. The results concerning the preparation of such lattices and their behaviour as solid polymer electrolytes are presented in this paper. (J.S.) 24 refs.

Novel differential refractometry study of the enzymatic degradation kinetics of poly(ethylene oxide)-b-poly(epsilon-caprolactone) particles dispersed in water.

Science.gov (United States)

Lam, HiuFung; Gong, Xiangjun; Wu, Chi

2007-02-22

A poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) diblock copolymer was micronized into small micelle-like particles (approximately 80 nm) via dialysis-induced microphase inversion. The enzymatic biodegradation of the PCL portion of these particles in water was in situ investigated inside a recently developed novel differential refractometer. Using this refractometry method, we were able to monitor the real-time biodegradation via the refractive index change (Deltan) of the dispersion because Deltan is directly proportional to the particle mass concentration. We found that the degradation rate is proportional to either the polymer or enzyme concentration. Our results directly support previous speculation on the basis of the light-scattering data that the biodegradation follows the first-order kinetics for a given enzyme concentration. This study not only leads to a better understanding of the enzymatic biodegradation of PCL, but also demonstrates a novel, rapid, noninvasive, and convenient way to test the degradability of polymers.

Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

Directory of Open Access Journals (Sweden)

Vorleak Chea

2014-10-01

Full Text Available This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR. The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1, consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2, whereas at the highest substrate concentration (500 mg·L−1, it was shown that the reaction was limited by the oxygen content.

Starch: chemistry, microstructure, processing and enzymatic degradation

Science.gov (United States)

Starch is recognized as one of the most abundant and important commodities containing value added attributes for a vast number of industrial applications. Its chemistry, structure, property and susceptibility to various chemical, physical and enzymatic modifications offer a high technological value ...

Radiation degradation and the subsequent enzymatic hydrolysis of waste paper

International Nuclear Information System (INIS)

Kamakura, M.; Kaetsu, I.

1982-01-01

Various studies have been carried out to find methods for the pretreatment of waste cellulosic materials to make them more susceptible to enzymatic hydrolysis. In the work reported here, the effects of preirradiating waste papers on subsequent enzymatic hydrolysis have been studied

A Miniature Membrane Reactor for Evaluation of Process Design Options on the Enzymatic Degradation of Pectin

DEFF Research Database (Denmark)

Zainal Alam, Muhd Nazrul Hisham; Pinelo, Manuel; Arnous, Anis

2011-01-01

was fabricated from poly(methylmethacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) with a working volume of ∼190 μL. The prototype also contained the necessary sensors and actuators, i.e., pressure transducer, mixing via magnetic stirrer bar and a temperature controller. The functionality of the prototype...... was demonstrated by performing a continuous enzymatic degradation of pectin experiment for a range of reactor conditions: different membrane molecular weight cutoff (MWCO) values, enzyme-to-substrate ratios (E/S), and substrate feeding rates (F) were assessed. Based on the experimental data, it was found...

Development of visible-light responsive and mechanically enhanced "smart" UCST interpenetrating network hydrogels.

Science.gov (United States)

Xu, Yifei; Ghag, Onkar; Reimann, Morgan; Sitterle, Philip; Chatterjee, Prithwish; Nofen, Elizabeth; Yu, Hongyu; Jiang, Hanqing; Dai, Lenore L

2017-12-20

An interpenetrating polymer network (IPN), chlorophyllin-incorporated environmentally responsive hydrogel was synthesized and exhibited the following features: enhanced mechanical properties, upper critical solution temperature (UCST) swelling behavior, and promising visible-light responsiveness. Poor mechanical properties are known challenges for hydrogel-based materials. By forming an interpenetrating network between polyacrylamide (PAAm) and poly(acrylic acid) (PAAc) polymer networks, the mechanical properties of the synthesized IPN hydrogels were significantly improved compared to hydrogels made of a single network of each polymer. The formation of the interpenetrating network was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), the analysis of glass transition temperature, and a unique UCST responsive swelling behavior, which is in contrast to the more prevalent lower critical solution temperature (LCST) behaviour of environmentally responsive hydrogels. The visible-light responsiveness of the synthesized hydrogel also demonstrated a positive swelling behavior, and the effect of incorporating chlorophyllin as the chromophore unit was observed to reduce the average pore size and further enhance the mechanical properties of the hydrogel. This interpenetrating network system shows potential to serve as a new route in developing "smart" hydrogels using visible-light as a simple, inexpensive, and remotely controllable stimulus.

Rheological behavior and non-enzymatic degradation of a sulfated galactan from Halymenia durvillei (Halymeniales, Rhodophyta).

Science.gov (United States)

Fenoradosoa, Taratra André; Laroche, Céline; Delattre, Cedric; Dulong, Virginie; Le Cerf, Didier; Picton, Luc; Michaud, Philippe

2012-07-01

The rheological behavior of a sulfated galactan extracted from Halymenia durvillei, a red seaweed collected in the coastal waters of a small island of Madagascar (Nosy-be in Indian Ocean), was investigated in dilute and semi-dilute solutions. In dilute solution with NaCl at 0.3 M, the polysaccharide adopted a coil conformation whereas, at higher concentrations, the polymer had the behavior of shear-thinning fluid, typical of polymer with high molar mass or semi-rigid conformation. Degradations of this lambda carrageenan-like, using radical depolymerization, and high-pressure homogenization led to several samples of various and controlled molar masses. The measure of their intrinsic viscosities permitted the determination of the relationship of Mark-Houwink-Sakurada.

Shape Memory Properties and Enzymatic Degradability of Poly(ε-caprolactone)-Based Polyurethane Urea Containing Phenylalanine-Derived Chain Extender.

Science.gov (United States)

Wang, Rong; Zhang, Fanjun; Lin, Weiwei; Liu, Wenkai; Li, Jiehua; Luo, Feng; Wang, Yaning; Tan, Hong

2018-04-24

Biodegradable shape memory polymers are promising biomaterials for minimally invasive surgical procedures. Herein, a series of linear biodegradable shape memory poly(ε-caprolactone) (PCL)-based polyurethane ureas (PUUs) containing a novel phenylalanine-derived chain extender is synthesized. The phenylalanine-derived chain extender, phenylalanine-hexamethylenediamine-phenylalanine (PHP), contains two chymotrypsin cleaving sites to enhance the enzymatic degradation of PUUs. The degradation rate, the crystallinity, and mechanical properties of PUUs are tailored by the content of PHP. Meanwhile, semicrystalline PCL is not only hydrolytically degradable but also vital for shape memory. Good shape memory ability under body temperature is achieved for PUUs due to the strong interactions in hard segments for permanent crosslinking and the crystallization-melt transition of PCL to switch temporary shape. The PUUs would have a great potential in application as implanting stent. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enzymatically and reductively degradable α-amino acid-based poly(ester amide)s: synthesis, cell compatibility, and intracellular anticancer drug delivery.

Science.gov (United States)

Sun, Huanli; Cheng, Ru; Deng, Chao; Meng, Fenghua; Dias, Aylvin A; Hendriks, Marc; Feijen, Jan; Zhong, Zhiyuan

2015-02-09

A novel and versatile family of enzymatically and reductively degradable α-amino acid-based poly(ester amide)s (SS-PEAs) were developed from solution polycondensation of disulfide-containing di-p-toluenesulfonic acid salts of bis-l-phenylalanine diesters (SS-Phe-2TsOH) with di-p-nitrophenyl adipate (NA) in N,N-dimethylformamide (DMF). SS-PEAs with Mn ranging from 16.6 to 23.6 kg/mol were obtained, depending on NA/SS-Phe-2TsOH molar ratios. The chemical structures of SS-PEAs were confirmed by (1)H NMR and FTIR spectra. Thermal analyses showed that the obtained SS-PEAs were amorphous with a glass transition temperature (Tg) in the range of 35.2-39.5 °C. The in vitro degradation studies of SS-PEA films revealed that SS-PEAs underwent surface erosion in the presence of 0.1 mg/mL α-chymotrypsin and bulk degradation under a reductive environment containing 10 mM dithiothreitol (DTT). The preliminary cell culture studies displayed that SS-PEA films could well support adhesion and proliferation of L929 fibroblast cells, indicating that SS-PEAs have excellent cell compatibility. The nanoparticles prepared from SS-PEA with PVA as a surfactant had an average size of 167 nm in phosphate buffer (PB, 10 mM, pH 7.4). SS-PEA nanoparticles while stable under physiological environment undergo rapid disintegration under an enzymatic or reductive condition. The in vitro drug release studies showed that DOX release was accelerated in the presence of 0.1 mg/mL α-chymotrypsin or 10 mM DTT. Confocal microscopy observation displayed that SS-PEA nanoparticles effectively transported DOX into both drug-sensitive and -resistant MCF-7 cells. MTT assays revealed that DOX-loaded SS-PEA nanoparticles had a high antitumor activity approaching that of free DOX in drug-sensitive MCF-7 cells, while more than 10 times higher than free DOX in drug-resistant MCF-7/ADR cells. These enzymatically and reductively degradable α-amino acid-based poly(ester amide)s have provided an appealing platform for

Degradation of microbial polyesters.

Science.gov (United States)

Tokiwa, Yutaka; Calabia, Buenaventurada P

2004-08-01

Microbial polyhydroxyalkanoates (PHAs), one of the largest groups of thermoplastic polyesters are receiving much attention as biodegradable substitutes for non-degradable plastics. Poly(D-3-hydroxybutyrate) (PHB) is the most ubiquitous and most intensively studied PHA. Microorganisms degrading these polyesters are widely distributed in various environments. Although various PHB-degrading microorganisms and PHB depolymerases have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. Distributions of PHB-degrading microorganisms, factors affecting the biodegradability of PHB, and microbial and enzymatic degradation of PHB are discussed in this review. We also propose an application of a new isolated, thermophilic PHB-degrading microorganism, Streptomyces strain MG, for producing pure monomers of PHA and useful chemicals, including D-3-hydroxycarboxylic acids such as D-3-hydroxybutyric acid, by enzymatic degradation of PHB.

Proton conducting semi-IPN based on Nafion and crosslinked poly(AMPS) for direct methanol fuel cell

International Nuclear Information System (INIS)

Cho, Ki-Yun; Jung, Ho-Young; Shin, Seung-Shik; Choi, Nam-Soon; Sung, Shi-Joon; Park, Jung-Ki; Choi, Jong-Ho; Park, Kyung-Won; Sung, Yung-Eun

2004-01-01

For direct methanol fuel cell, the proton conducting membrane based on semi-interpenetrating polymer networks (IPNs) of Nafion and crosslinked poly(AMPS) was prepared and characterized. The modification of Nafion with crosslinked poly(AMPS) such as hydrocarbon polymer changed the state of water in membranes. Without a significant increase of the membrane resistance, the semi-IPNs demonstrated a reduction of the methanol permeability, comparing to the native Nafion. And the maximum power density of AMPS60 increased as much as 22.2% compared with Nafion

Enzyme kinetics and identification of the rate-limiting step of enzymatic arabinoxylan degradation

DEFF Research Database (Denmark)

Rasmussen, Louise Enggaard; Xu, Cheng; Sørensen, Jens

2012-01-01

This study investigated the kinetics of multi-enzymatic degradation of soluble wheat arabinoxylan by monitoring the release of xylose and arabinose during designed treatments with mono-component enzymes at different substrate concentrations. The results of different combinations of α...... α-l-arabinofuranosidases catalyze liberation of arabinose residues linked 1→3 to singly (AFAn) or doubly (AFBa) substituted xyloses in arabinoxylan, respectively. When added to arabinoxylan at equimolar levels, the AFBa enzyme catalyzed the release of more arabinose, i.e. had a higher rate constant...... than AFAn, but with respect to the xylose release, AFAn – as expected – exhibited a better synergistic effect than AFBa with β-xylosidase. This synergistic effect with AFAn was estimated to increase the number of β-xylosidase catalyzed cuts from ∼3 (with β-xylosidase alone) to ∼7 in each arabinoxylan...

Interpenetrating metal-organic and inorganic 3D networks: a computer-aided systematic investigation. Part II [1]. Analysis of the Inorganic Crystal Structure Database (ICSD)

International Nuclear Information System (INIS)

Baburin, I.A.; Blatov, V.A.; Carlucci, L.; Ciani, G.; Proserpio, D.M.

2005-01-01

Interpenetration in metal-organic and inorganic networks has been investigated by a systematic analysis of the crystallographic structural databases. We have used a version of TOPOS (a package for multipurpose crystallochemical analysis) adapted for searching for interpenetration and based on the concept of Voronoi-Dirichlet polyhedra and on the representation of a crystal structure as a reduced finite graph. In this paper, we report comprehensive lists of interpenetrating inorganic 3D structures from the Inorganic Crystal Structure Database (ICSD), inclusive of 144 Collection Codes for equivalent interpenetrating nets, analyzed on the basis of their topologies. Distinct Classes, corresponding to the different modes in which individual identical motifs can interpenetrate, have been attributed to the entangled structures. Interpenetrating nets of different nature as well as interpenetrating H-bonded nets were also examined

Effect of electron beam irradiation on the enzymatic degradation of composites based on biodegradable polymers and coconut fiber

Energy Technology Data Exchange (ETDEWEB)

Kodama, Yasko; Bardi, Marcelo Augusto Goncalves; Machado, Luci Diva Brocardo, E-mail: ykodama@ipen.b, E-mail: marcelo.bardi@usp.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Rosa, Derval dos Santos, E-mail: derval.rosa@ufabc.edu.b [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

2011-07-01

The development of polymeric materials that are susceptible to microbiological degradation and that have properties similar to the conventional polymers would reduce waste deposit. Degradable plastics suffer significant change on chemical structure when submitted to specific environmental condition. PCL and PLLA have been extensively investigated due to their bio-assimilation and because they are considered as eco-friendly. So the degradation of PCL and PLLA homopolymers, PCL:PLLA 20:80 (w:w) blend and coconut fiber-modified composites were studied by means of their degradation under lipase enzyme from Pseudomonas cepacia. Non-irradiated and EB-irradiated samples at 50 kGy and 100 kGy were exposed during 24, 72, 120 and 168 hours to the enzyme-buffer solution and the retained mass of dried samples was accompanied over time. The results were compared to the not submitted to the enzyme solution samples. Degradation rate of PCL was higher than PLLA in the presence of Pseudomonas lipase. PLLA presence reduced PCL's enzymatic degradation in the PCL:PLLA 20:80 w:w blend. After 120 h exposure, blend mass loss variation approached pure PLLA behavior. Composites degradation behavior through time was similar to the blend. Values of retained mass for composites were superior to the blends suggesting that coconut fiber did not significantly degrade in the period of test. Degradation rate of 50 kGy-irradiated PCL slightly reduced, and it was observed increase of degradation rate of samples irradiated with 100 kGy, probably attributed to its crystallinity decrease. Degradation rate of irradiated composite was similar to the blend, suggesting that fiber presence did not affect significantly this parameter. Samples tested during 168 h were affected by the water absorption by PLLA or coconut fibers through time testing. Studied samples degraded accentuatedly in the enzyme presence and were not negatively affected by the radiation processing. (author)

Effect of electron beam irradiation on the enzymatic degradation of composites based on biodegradable polymers and coconut fiber

International Nuclear Information System (INIS)

Kodama, Yasko; Bardi, Marcelo Augusto Goncalves; Machado, Luci Diva Brocardo; Rosa, Derval dos Santos

2011-01-01

The development of polymeric materials that are susceptible to microbiological degradation and that have properties similar to the conventional polymers would reduce waste deposit. Degradable plastics suffer significant change on chemical structure when submitted to specific environmental condition. PCL and PLLA have been extensively investigated due to their bio-assimilation and because they are considered as eco-friendly. So the degradation of PCL and PLLA homopolymers, PCL:PLLA 20:80 (w:w) blend and coconut fiber-modified composites were studied by means of their degradation under lipase enzyme from Pseudomonas cepacia. Non-irradiated and EB-irradiated samples at 50 kGy and 100 kGy were exposed during 24, 72, 120 and 168 hours to the enzyme-buffer solution and the retained mass of dried samples was accompanied over time. The results were compared to the not submitted to the enzyme solution samples. Degradation rate of PCL was higher than PLLA in the presence of Pseudomonas lipase. PLLA presence reduced PCL's enzymatic degradation in the PCL:PLLA 20:80 w:w blend. After 120 h exposure, blend mass loss variation approached pure PLLA behavior. Composites degradation behavior through time was similar to the blend. Values of retained mass for composites were superior to the blends suggesting that coconut fiber did not significantly degrade in the period of test. Degradation rate of 50 kGy-irradiated PCL slightly reduced, and it was observed increase of degradation rate of samples irradiated with 100 kGy, probably attributed to its crystallinity decrease. Degradation rate of irradiated composite was similar to the blend, suggesting that fiber presence did not affect significantly this parameter. Samples tested during 168 h were affected by the water absorption by PLLA or coconut fibers through time testing. Studied samples degraded accentuatedly in the enzyme presence and were not negatively affected by the radiation processing. (author)

Pros and Cons of the Interpenetrating Panel Design

Science.gov (United States)

Paul C. Van Deusen

2000-01-01

The interpenetrating sample design has been selected for the USDA Forest Service's Annual Forest Inventory System. The advantages and disadvantages of this design are discussed by considering alternatives such as the formerly used periodic design, a concentrated grid design, and disturbance based sampling. Factors considered for each design include fulfilling 1998...

Selective Adsorption of Ethane over Ethylene in PCN-245: Impacts of Interpenetrated Adsorbent.

Science.gov (United States)

Lv, Daofei; Shi, Renfeng; Chen, Yongwei; Wu, Ying; Wu, Houxiao; Xi, Hongxia; Xia, Qibin; Li, Zhong

2018-03-07

The separation of ethane from ethylene using cryogenic distillation is an energy-intensive process in the industry. With lower energetic consumption, the adsorption technology provides the opportunities for developing the industry with economic sustainability. We report an iron-based metal-organic framework PCN-245 with interpenetrated structures as an ethane-selective adsorbent for ethylene/ethane separation. The material maintains stability up to 625 K, even after exposure to 80% humid atmosphere for 20 days. Adsorptive separation experiments on PCN-245 at 100 kPa and 298 K indicated that ethane and ethylene uptakes of PCN-245 were 3.27 and 2.39 mmol, respectively, and the selectivity of ethane over ethylene was up to 1.9. Metropolis Monte Carlo calculations suggested that the interpenetrated structure of PCN-245 created greater interaction affinity for ethane than ethylene through the crossing organic linkers, which is consistent with the experimental results. This work highlights the potential application of adsorbents with the interpenetrated structure for ethane separation from ethylene.

Efficiency of new fungal cellulase systems in boosting enzymatic degradation of barley straw lignocellulose

DEFF Research Database (Denmark)

Rosgaard, L.; Pedersen, S.; Meyer, Anne Boye Strunge

2006-01-01

This study examined the cellulytic effects on steam-pretreated barley straw of cellulose-degrading enzyme systems from the five thermophilic fungi Chaetomium thermophilum, Thielavia terrestris, Thermoascus aurantiacus, Corynascus thermophilus, and Myceliophthora thermophila and from the mesophile...... Penicillum funiculosum. The catalytic glucose release was compared after treatments with each of the crude enzyme systems when added to a benchmark blend of a commercial cellulase product, Celluclast, derived from Trichoderma reesei and a P-glucosidase, Novozym 188, from Aspergillus niger. The enzymatic...... treatments were evaluated in an experimental design template comprising a span of pH (3.5-6.5) and temperature (35-65 degrees C) reaction combinations. The addition to Celluclast + Novozym 188 of low dosages of the crude enzyme systems, corresponding to 10 wt % of the total enzyme protein load, increased...

Effect of in vitro enzymatic degradation on 3D printed poly(ε-caprolactone) scaffolds: morphological, chemical and mechanical properties.

Science.gov (United States)

Ferreira, Joana; Gloria, Antonio; Cometa, Stefania; Coelho, Jorge F J; Domingos, Marco

2017-07-27

In recent years, the tissue engineering (TE) field has significantly benefited from advanced techniques such as additive manufacturing (AM), for the design of customized 3D scaffolds with the aim of guided tissue repair. Among the wide range of materials available to biomanufacture 3D scaffolds, poly(ε-caprolactone) (PCL) clearly arises as the synthetic polymer with the greatest potential, due to its unique properties - namely, biocompatibility, biodegradability, thermal and chemical stability and processability. This study aimed for the first time to investigate the effect of pore geometry on the in vitro enzymatic chain cleavage mechanism of PCL scaffolds manufactured by the AM extrusion process. Methods: Morphological properties of 3D printed PCL scaffolds before and after degradation were evaluated using Scanning Electron Microscopy (SEM) and micro-computed tomography (μ-CT). Differential Scanning Calorimetry (DSC) was employed to determine possible variations in the crystallinity of the scaffolds during the degradation period. The molecular weight was assessed using Size Exclusion Chromatography (SEC) while the mechanical properties were investigated under static compression conditions. Morphological results suggested a uniform reduction of filament diameter, while increasing the scaffolds' porosity. DSC analysis revealed and increment in the crystallinity degree while the molecular weight, evaluated through SEC, remained almost constant during the incubation period (25 days). Mechanical analysis highlighted a decrease in the compressive modulus and maximum stress over time, probably related to the significant weight loss of the scaffolds. All of these results suggest that PCL scaffolds undergo enzymatic degradation through a surface erosion mechanism, which leads to significant variations in mechanical, physical and chemical properties, but which has little influence on pore geometry.

pH catalyzed pretreatment of corn bran for enhanced enzymatic arabinoxylan degradation

DEFF Research Database (Denmark)

Agger, Jane; Johansen, Katja Salomon; Meyer, Anne S.

2011-01-01

Corn bran is mainly made up of the pericarp of corn kernels and is a byproduct stream resulting from the wet milling step in corn starch processing. Through statistic modeling this study examined the optimization of pretreatment of corn bran for enzymatic hydrolysis. A low pH pretreatment (pH 2......, 150°C, 65min) boosted the enzymatic release of xylose and glucose and maximized biomass solubilization. With more acidic pretreatment followed by enzymatic hydrolysis the total xylose release was maximized (at pH 1.3) reaching ∼50% by weight of the original amount present in destarched corn bran......, but the enzyme catalyzed xylose release was maximal after pretreatment at approx. pH 2. The total glucose release peaked after pretreatment of approx. pH 1.5 with an enzymatic release of approx. 68% by weight of the original amounts present in destarched corn bran. For arabinose the enzymatic release...

Two interpenetrating Cu{sup II}/Ni{sup II}-coordinated polymers based on an unsymmetrical bifunctional N/O-tectonic: Syntheses, structures and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Liu, Yong-Liang [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Department of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources, Shang Luo University, Shang Luo 726000 (China); Wu, Ya-Pan [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Li, Dong-Sheng, E-mail: lidongsheng1@126.com [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Dong, Wen-Wen [College of Materials & Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Zhou, Chun-Sheng [Department of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources, Shang Luo University, Shang Luo 726000 (China)

2015-03-15

Two new interpenetrating Cu{sup II}/Ni{sup II} coordination polymers, based on a unsymmetrical bifunctional N/O-tectonic 3-(pyrid-4′-yl)-5-(4″-carbonylphenyl)-1,2,4-triazolyl (H{sub 2}pycz), ([Cu-(Hpycz){sub 2}]·2H{sub 2}O){sub n} (1) and ([Ni(Hpycz){sub 2}]·H{sub 2}O){sub n} (2), have been solvothermally synthesized and structure characterization. Single crystal X-ray analysis indicates that compound 1 shows 2-fold parallel interpenetrated 4{sup 4}-sql layers with the same handedness. The overall structure of 1 is achiral—in each layer of doubly interpenetrating nets, the two individual nets have the opposite handedness to the corresponding nets in the adjoining layers—while 2 features a rare 8-fold interpenetrating 6{sup 6}-dia network that belongs to class IIIa interpenetration. In addition, compounds 1 and 2 both show similar paramagnetic characteristic properties. - Graphical abstract: Two new Cu(II)/Ni(II) coordination polymers present 2D parallel 2-fold interpenetrated 4{sup 4}-sql layers and a rare 3D 8-fold interpenetrating 6{sup 6}-dia network. In addition, magnetic susceptibility measurements show similar paramagnetic characteristic for two complexes. - Highlights: • A new unsymmetrical bifunctional N/O-tectonic as 4-connected spacer. • A 2-fold parallel interpenetrated sql layer with the same handedness. • A rare 8-fold interpenetrating dia network (class IIIa)

Thermal stability and degradation kinetics of polyphenols and polyphenylenediamines enzymatically synthesized by horseradish peroxidase

Energy Technology Data Exchange (ETDEWEB)

Park, Hansol; Ryu, Keungarp [University of Ulsan, Ulsan (Korea, Republic of); Kwon, Oyul [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

2015-09-15

Various substituted phenols and phenylenediamines were enzymatically polymerized by horseradish peroxidase in 80% (v/v) organic solvents-aqueous buffer (100 mM sodium acetate, pH 5) mixtures with H{sub 2}O{sub 2} as the oxidant. The thermal stability of the polymers was investigated by thermogravimetric analysis (TGA) and represented by the char yield (wt% of the initial polymer mass) after being heated at 800 .deg. C. Poly(p-phenylphenol) had the highest thermal stability among the synthesized polymers with a char yield of 47 wt%. The polymers containing amino groups such as poly(p-aminophenol) and polyphenylenediamines were also shown to possess high thermal stabilities. The activation energies for the thermal degradation of the polymers determined by derivative thermogravimetric analysis (DTG) using Horowitz-Metzger's pseudo-first-order kinetics were in the range between 23-65 kJ/mol and comparable to those of the chemically synthesized polymers. Dynamic structural changes of the enzymatically synthesized polymers upon heating were studied by differential scanning calorimetry (DSC). The DSC curves of poly(p-phenylphenol) showed a broad exothermic peaks between 150-250 .deg. C, indicating that the polymer undergoes complex structural transitions in the temperature range. On the other hand, the DSC curves of the poly(p-aminophenol) and the poly(p-phenylenediamine) which contain amino groups showed strong sharp endothermic peaks near 150 .deg. C, implying that these polymers possess homogeneous oriented structures which undergo a concerted structural disintegration upon heating.

Thermal stability and degradation kinetics of polyphenols and polyphenylenediamines enzymatically synthesized by horseradish peroxidase

International Nuclear Information System (INIS)

Park, Hansol; Ryu, Keungarp; Kwon, Oyul

2015-01-01

Various substituted phenols and phenylenediamines were enzymatically polymerized by horseradish peroxidase in 80% (v/v) organic solvents-aqueous buffer (100 mM sodium acetate, pH 5) mixtures with H 2 O 2 as the oxidant. The thermal stability of the polymers was investigated by thermogravimetric analysis (TGA) and represented by the char yield (wt% of the initial polymer mass) after being heated at 800 .deg. C. Poly(p-phenylphenol) had the highest thermal stability among the synthesized polymers with a char yield of 47 wt%. The polymers containing amino groups such as poly(p-aminophenol) and polyphenylenediamines were also shown to possess high thermal stabilities. The activation energies for the thermal degradation of the polymers determined by derivative thermogravimetric analysis (DTG) using Horowitz-Metzger's pseudo-first-order kinetics were in the range between 23-65 kJ/mol and comparable to those of the chemically synthesized polymers. Dynamic structural changes of the enzymatically synthesized polymers upon heating were studied by differential scanning calorimetry (DSC). The DSC curves of poly(p-phenylphenol) showed a broad exothermic peaks between 150-250 .deg. C, indicating that the polymer undergoes complex structural transitions in the temperature range. On the other hand, the DSC curves of the poly(p-aminophenol) and the poly(p-phenylenediamine) which contain amino groups showed strong sharp endothermic peaks near 150 .deg. C, implying that these polymers possess homogeneous oriented structures which undergo a concerted structural disintegration upon heating.

Interpenetrated Uranyl-Organic Frameworks with bor and pts Topology: Structure, Spectroscopy, and Computation.

Science.gov (United States)

Liu, Chao; Chen, Fang-Yuan; Tian, Hong-Rui; Ai, Jing; Yang, Weiting; Pan, Qing-Jiang; Sun, Zhong-Ming

2017-11-20

Two novel three-dimensional interpenetrated uranyl-organic frameworks, (NH 4 ) 4 [(UO 2 ) 4 (L 1 ) 3 ]·6H 2 O (1) and [(UO 2 ) 2 (H 2 O) 2 L 2 ]·2H 2 O (2), where L 1 = tetrakis(3-carboxyphenyl)silicon and L 2 = tetrakis(4-carboxyphenyl)silicon, were synthesized by a combination of two isomeric tetrahedral silicon-centered ligands with 3-connected triangular [(UO 2 )(COO) 3 ] - and 4-connected dinuclear [(UO 2 ) 2 (COO) 4 ] units, respectively. Structural analyses indicate that 1 possesses a 2-fold interpenetrating anion bor network, while 2 exhibits a 3-fold interpenetrated 4,4-connected neutral network with pts topology. Both compounds were characterized by thermogravimetric analysis and IR, UV-vis, and photoluminescence spectroscopy. A relativistic density functional theory (DFT) investigation on 10 model compounds of 1 and 2 shows good agreement of the structural parameters, stretching vibrational frequencies, and absorption with experimental results; the time-dependent DFT calculations unravel that low-energy absorption bands originate from ligand-to-uranium charge transfer.

Lignin from hydrothermally pretreated grass biomass retards enzymatic cellulose degradation by acting as a physical barrier rather than by inducing nonproductive adsorption of enzymes

DEFF Research Database (Denmark)

Djajadi, Demi T.; Jensen, Mads M.; Oliveira, Marlene

2018-01-01

-rich residues (LRRs) were prepared via extensive enzymatic cellulose degradation of corn stover (Zea mays subsp. mays L.), Miscanthus × giganteus stalks (MS) and wheat straw (Triticum aestivum L.) (WS) samples that each had been hydrothermally pretreated at three severity factors (log R0) of 3.65, 3.83 and 3...

Lignin degradation: microorganisms, enzymes involved, genomes analysis and evolution.

Science.gov (United States)

Janusz, Grzegorz; Pawlik, Anna; Sulej, Justyna; Swiderska-Burek, Urszula; Jarosz-Wilkolazka, Anna; Paszczynski, Andrzej

2017-11-01

Extensive research efforts have been dedicated to describing degradation of wood, which is a complex process; hence, microorganisms have evolved different enzymatic and non-enzymatic strategies to utilize this plentiful plant material. This review describes a number of fungal and bacterial organisms which have developed both competitive and mutualistic strategies for the decomposition of wood and to thrive in different ecological niches. Through the analysis of the enzymatic machinery engaged in wood degradation, it was possible to elucidate different strategies of wood decomposition which often depend on ecological niches inhabited by given organism. Moreover, a detailed description of low molecular weight compounds is presented, which gives these organisms not only an advantage in wood degradation processes, but seems rather to be a new evolutionatory alternative to enzymatic combustion. Through analysis of genomics and secretomic data, it was possible to underline the probable importance of certain wood-degrading enzymes produced by different fungal organisms, potentially giving them advantage in their ecological niches. The paper highlights different fungal strategies of wood degradation, which possibly correlates to the number of genes coding for secretory enzymes. Furthermore, investigation of the evolution of wood-degrading organisms has been described. © FEMS 2017.

SANS from interpenetrating polymer networks

International Nuclear Information System (INIS)

Markotsis, M.G.; Burford, R.P.; Knott, R.B.; Australian Nuclear Science and Technology Organisation, Menai, NSW; Hanley, T.L.; CRC for Polymers,; Australian Nuclear Science and Technology Organisation, Menai, NSW; Papamanuel, N.

2003-01-01

Full text: Interpenetrating polymer networks (IPNs) have been formed by combining two polymeric systems in order to gain enhanced material properties. IPNs are a combination of two or more polymers in network form with one network polymerised and/or crosslinked in the immediate presence of the other(s).1 IPNs allow better blending of two or more crosslinked networks. In this study two sets of IPNs were produced and their microstructure studied using a variety of techniques including small angle neutron scattering (SANS). The first system combined a glassy polymer (polystyrene) with an elastomeric polymer (SBS) with the glassy polymer predominating, to give a high impact plastic. The second set of IPNs contained epichlorohydrin (CO) and nitrile rubber (NBR), and was formed in order to produce novel materials with enhanced chemical and gas barrier properties. In both cases if the phase mixing is optimised the probability of controlled morphologies and synergistic behaviour is increased. The PS/SBS IPNs were prepared using sequential polymerisation. The primary SBS network was thermally crosslinked, then the polystyrene network was polymerised and crosslinked using gamma irradiation to avoid possible thermal degradation of the butadiene segment of the SBS. Tough transparent systems were produced with no apparent thermal degradation of the polybutadiene segments. The epichlorohydrin/nitrile rubber IPNs were formed by simultaneous thermal crosslinking reactions. The epichlorohydrin network was formed using lead based crosslinker, while the nitrile rubber was crosslinked by peroxide methods. The use of two different crosslinking systems was employed in order to achieve independent crosslinking thus resulting in an IPN with minimal grafting between the component networks. SANS, Transmission electron microscopy (TEM), and atomic force microscopy (AFM) were used to examine the size and shape of the phase domains and investigate any variation with crosslinking level and

Silk Fibroin/Polyvinyl Pyrrolidone Interpenetrating Polymer Network Hydrogels

Directory of Open Access Journals (Sweden)

Dajiang Kuang

2018-02-01

Full Text Available Silk fibroin hydrogel is an ideal model as biomaterial matrix due to its excellent biocompatibility and used in the field of medical polymer materials. Nevertheless, native fibroin hydrogels show poor transparency and resilience. To settle these drawbacks, an interpenetrating network (IPN of hydrogels are synthesized with changing ratios of silk fibroin/N-Vinyl-2-pyrrolidonemixtures that crosslink by H2O2 and horseradish peroxidase. Interpenetrating polymer network structure can shorten the gel time and the pure fibroin solution gel time for more than a week. This is mainly due to conformation from the random coil to the β-sheet structure changes of fibroin. Moreover, the light transmittance of IPN hydrogel can be as high as more than 97% and maintain a level of 90% within a week. The hydrogel, which mainly consists of random coil, the apertures inside can be up to 200 μm. Elastic modulus increases during the process of gelation. The gel has nearly 95% resilience under the compression of 70% eventually, which is much higher than native fibroin gel. The results suggest that the present IPN hydrogels have excellent mechanical properties and excellent transparency.

Enhanced adsorption of methyl violet and congo red by using semi and full IPN of polymethacrylic acid and chitosan.

Science.gov (United States)

Maity, Jayabrata; Ray, Samit Kumar

2014-04-15

Semi and full interpenetrating polymer network (IPN) type hydrogels were prepared by free radical in situ polymerization of methacrylic acid in presence of chitosan using N,N'-methylene-bis-acrylamide (MBA) and glutaraldehyde (for full IPN) as crosslinker. Several semi and full IPN type hydrogels were prepared by varying initiator and crosslinker concentration and also monomer to chitosan mass ratio. These hydrogels were characterized and used for removal of methyl violet and congo red dye from water. Isotherms and kinetics of dye adsorption were also evaluated. Copyright © 2014 Elsevier Ltd. All rights reserved.

Static semicoercive normal compliance contact problem with limited interpenetration

Czech Academy of Sciences Publication Activity Database

Jarušek, Jiří

2015-01-01

Roč. 66, č. 5 (2015), s. 2161-2172 ISSN 0044-2275 R&D Projects: GA ČR(CZ) GAP201/12/0671 Institutional support: RVO:67985840 Keywords : contact * limited interpenetration * friction Subject RIV: BA - General Mathematics Impact factor: 1.560, year: 2015 http://link.springer.com/article/10.1007%2Fs00033-015-0539-5

Morphology and damping behavior of polyurethane/PMMA simultaneous interpenetrating networks

Directory of Open Access Journals (Sweden)

Wang S.H.

2001-01-01

Full Text Available A series of polyurethane/PMMA simultaneous interpenetrating networks (SINs with various hard segment contents (X in the polyurethane phase (X = 15.5 to 36.5% in polyurethane and wide range of polyurethane (PU to polyacrylate (PA ratio (PU/PA = 20:80 to 80:20 were prepared, and the damping and mechanical properties of these materials were studied. The damping of polyurethane soft phase was increased and shifted to lower temperature with increased content of PA vitreous phase. The mechanical properties were improved with increasing PA contents. The results show that PA and the polyurethane hard segment interaction play a special role in chain interpenetration density and its magnitude is revealed by the decreased dispersed domain size observed by scanning electron microscopy (SEM and increased loss area as measured by dynamic mechanical thermal analysis (DMTA. When the weight ratio of PU/PA was 40:60, the resulting SIN materials possessed better damping properties, independent of X concentration.

Beneficial effect of mixture of additives amendment on enzymatic activities, organic matter degradation and humification during biosolids co-composting.

Science.gov (United States)

Awasthi, Mukesh Kumar; Wang, Quan; Chen, Hongyu; Awasthi, Sanjeev Kumar; Wang, Meijing; Ren, Xiuna; Zhao, Junchao; Zhang, Zengqiang

2018-01-01

The objective of this study was to identify the effect of mixture of additives to improve the enzymatic activities, organic matter humification and diminished the bioavailability of heavy metals (HMs) during biosolids co-composting. In this study, zeolite (Z) (10%, 15% and 30%) with 1%lime (L) (dry weight basis of biosolids) was blended into the mixture of biosolids and wheat straw, respectively. The without any amendment and 1%lime applied treatments were run for comparison (Control). The Z+L addition resulted rapid organic matter degradation and humification with maximum enzymatic activities. In addition, higher dosage of Z+1%L amendment reduced the bioavailability of HMs (Cu and Zn) and improved the end product quality as compared to control and 1%L applied treatments. However, the 30%Z+1%L applied treatment showed maximum humification and low bioavailability of HMs but considering the economic feasibility and compost quality results, the treatment with 10%Z+1%L is recommended for biosolids co-composting. Copyright © 2017 Elsevier Ltd. All rights reserved.

Study of Enzymatic Degradation Comparison of CPP/Bionolle and CPP/PCL Blend with Modic

International Nuclear Information System (INIS)

Nikham; Makuuchi, K.; Yoshii, Fumeo

2000-01-01

Melt-blending poly propylene-co-ethylene (CPP)/poly butylene succinate (Bionolle), CPP/polyεcaprolactone (PCL) with polypropylene grafted maleic anhydride (Modic) as compatibilizer has been studied. The effect of Modic concentration on the compatibility was evaluated using the ultimate elongation at break, tensile strength and SEM micrographs. The Result show that 20 wt % and 10 % wt of Medic appears to be an optimum concentration for CPP/Bionolle and CPP/PCL blend respectively, as indicated by relatively high elongation at breaks, tensile strength and formation of co-continuous phase in the blend morphology. Enzymatic degradation of the CPP/Bionolle and CPP/PCL blend with 10 wt % of Modic was carried out using lipase AK enzyme in the phospate buffer solution pH 7.0 and incubated at the fixed temperature for 8 days. The result show that about 15 % and 86 % weight loss film of composition CPP/Bionolle>25/75 and CPP/PCL >25/75 blend respectively has been reached

Radiation preparation of interpenetrating polymer networks

International Nuclear Information System (INIS)

Sheikh, N.; Ahmadi, M.; Afshar Taromi, F.

2002-01-01

Sequential interpenetrating polymer netwoks were prepared using gamma radiation. Styrene-butadiene rubber (SBR) and polymethyl methacrylate (PMMA) were used as elastomer and plastomer components respectively. Dicumyl peroxide (DCP) and ethylene glycol dimethacrylate (EGDMA) were also used as the curing agent of SBR and crosslinker for MMA monomer. The resulting IPNs were characterized by evaluating their mechanical properties. The effect of the amount of DCP on the final properties of product was examined. It was found that amount of curing agent had an important role on the properties of obtained IPNS. The results of the mechanical properties of IPNs showed very good synergistic behavior. (Author)

Synthesis of wheat straw cellulose-g-poly (potassium acrylate)/PVA semi-IPNs superabsorbent resin.

Science.gov (United States)

Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu; Wang, Rui

2013-04-15

To better use wheat straw and minimize its negative impact on environment, a novel semi-interpenetrating polymer networks (semi-IPNs) superabsorbent resin (SAR) composed of wheat straw cellulose-g-poly (potassium acrylate) (WSC-g-PKA) network and linear polyvinyl alcohol (PVA) was prepared by polymerization in the presence of a redox initiating system. The structure and morphology of semi-IPNs SAR were characterized by means of FTIR, SEM and TGA, which confirmed that WSC and PVA participated in the graft polymerization reaction with acrylic acid (AA). The factors that can influence the water absorption of the semi-IPNs SAR were investigated and optimized, including the weight ratios of AA to WSC and PVA to WSC, the content of initiator and crosslinker, neutralization degree (ND) of AA, reaction temperature and time. The semi-IPNs SAR prepared under optimized synthesis condition gave the best water absorption of 266.82 g/g in distilled water and 34.32 g/g in 0.9 wt% NaCl solution. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sexual crossing of thermophilic fungus Myceliophthora heterothallica improved enzymatic degradation of sugar beet pulp.

Science.gov (United States)

Aguilar-Pontes, Maria Victoria; Zhou, Miaomiao; van der Horst, Sjors; Theelen, Bart; de Vries, Ronald P; van den Brink, Joost

2016-01-01

Enzymatic degradation of plant biomass requires a complex mixture of many different enzymes. Like most fungi, thermophilic Myceliophthora species therefore have a large set of enzymes targeting different linkages in plant polysaccharides. The majority of these enzymes have not been functionally characterized, and their role in plant biomass degradation is unknown. The biotechnological challenge is to select the right set of enzymes to efficiently degrade a particular biomass. This study describes a strategy using sexual crossing and screening with the thermophilic fungus Myceliophthora heterothallica to identify specific enzymes associated with improved sugar beet pulp saccharification. Two genetically diverse M. heterothallica strains CBS 203.75 and CBS 663.74 were used to generate progenies with improved growth on sugar beet pulp. One progeny, named SBP.F1.2.11, had a different genetic pattern from the parental strains and had improved saccharification activity after the growth on 3 % sugar beet pulp. The improved SBP saccharification was not explained by altered activities of the major (hemi-)cellulases. Exo-proteome analysis of progeny and parental strains after 7-day growth on sugar beet pulp showed that only 17 of the 133 secreted CAZy enzymes were more abundant in progeny SBP.F1.2.11. Particularly one enzyme belonging to the carbohydrate esterase family 5 (CE5) was more abundant in SBP.F1.2.11. This CE5-CBM1 enzyme, named as Axe1, was phylogenetically related to acetyl xylan esterases. Biochemical characterization of Axe1 confirmed de-acetylation activity with optimal activities at 75-85 °C and pH 5.5-6.0. Supplementing Axe1 to CBS 203.75 enzyme set improved release of xylose and glucose from sugar beet pulp. This study identified beneficial enzymes for sugar beet pulp saccharification by selecting progeny with improved growth on this particular substrate. Saccharification of sugar beet pulp was improved by supplementing enzyme mixtures with a previously

Enzymatically crosslinked silk-hyaluronic acid hydrogels.

Science.gov (United States)

Raia, Nicole R; Partlow, Benjamin P; McGill, Meghan; Kimmerling, Erica Palma; Ghezzi, Chiara E; Kaplan, David L

2017-07-01

In this study, silk fibroin and hyaluronic acid (HA) were enzymatically crosslinked to form biocompatible composite hydrogels with tunable mechanical properties similar to that of native tissues. The formation of di-tyrosine crosslinks between silk fibroin proteins via horseradish peroxidase has resulted in a highly elastic hydrogel but exhibits time-dependent stiffening related to silk self-assembly and crystallization. Utilizing the same method of crosslinking, tyramine-substituted HA forms hydrophilic and bioactive hydrogels that tend to have limited mechanics and degrade rapidly. To address the limitations of these singular component scaffolds, HA was covalently crosslinked with silk, forming a composite hydrogel that exhibited both mechanical integrity and hydrophilicity. The composite hydrogels were assessed using unconfined compression and infrared spectroscopy to reveal of the physical properties over time in relation to polymer concentration. In addition, the hydrogels were characterized by enzymatic degradation and for cytotoxicity. Results showed that increasing HA concentration, decreased gelation time, increased degradation rate, and reduced changes that were observed over time in mechanics, water retention, and crystallization. These hydrogel composites provide a biologically relevant system with controllable temporal stiffening and elasticity, thus offering enhanced tunable scaffolds for short or long term applications in tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stagnation and interpenetration of laser-created colliding plasmas

Energy Technology Data Exchange (ETDEWEB)

Pollaine, S.M.; Albritton, J.R.; Kauffman, R.; Keane, C.J. (Lawrence Livermore National Lab., CA (USA)); Berger, R.L.; Bosch, R.; Delameter, N.D.; Failor, B.H. (KMS Fusion, Inc., Ann Arbor, MI (USA))

1990-11-05

A KMS laser experiment collides Aluminum (A1) and Magnesium (Mg) plasmas. The measurements include electron density, time and space resolved Ly-alpha and He-alpha lines of Al and Mg, and x-ray images. These measurements were analyzed with a hydrodynamic code, LASNEX, and a special two-fluid code OFIS. The results strongly suggest that at early times, the Al interpenetrates the counterstreaming Mg and deposits in the dense Mg region. At late times, the Al plasma stagnates against the Mg plasma.

Starch and chitosan oligosaccharides as interpenetrating phases in poly(N-isopropylacrylamide) injectable gels

Energy Technology Data Exchange (ETDEWEB)

Vieira, Jacquelin N.; Posada, James J. [Chemistry Department, B" 5IDA Research Group, Universidad Simón Bolívar, Caracas (Venezuela, Bolivarian Republic of); Rezende, Rodrigo A. [Divisão de Tecnologias Tridimensionais–Centro de Tecnologia da Informação Renato Archer, Campinas, SP (Brazil); Sabino, Marcos A., E-mail: msabino@usb.ve [Chemistry Department, B" 5IDA Research Group, Universidad Simón Bolívar, Caracas (Venezuela, Bolivarian Republic of); Divisão de Tecnologias Tridimensionais–Centro de Tecnologia da Informação Renato Archer, Campinas, SP (Brazil)

2014-04-01

Thermosensitive interpenetrating gels were prepared by physically blending poly(N-isopropylacrylamide) (PNIPA) as the matrix and the following polysaccharides as interpenetrating phases: chitosan oligosaccharides (identified as QNAD and QNED) and soluble starch (STARCH). The molecular weight of the dispersed phase, the free water/bound water ratio and the thermosensitivity (transition temperature: LCST) of the gels were determined. It was found that these gels are pseudoplastic and that their viscosity depends on the molecular weight of the dispersed phase. LCST transition occurred around 35–37 °C. The morphology of the porosity of the freeze-dried samples was studied by Scanning Electron Microscopy (SEM). An in vitro test of cell hemolysis on blood agar showed that these gels are noncytotoxic. According to the results obtained, these interpenetrating gels show characteristics of an injectable material, and have a transition LCST at body temperature, which reinforces their potential to be used in the surgical field and as scaffolds for tissue engineering. - Highlights: • Physical blends were prepared to obtain thermosensitive gels PNIPA/polysaccharides. • Rheological test allowed verifying the injectability of the gels. • Gels showed a LCST ∼ 37 °C, which makes them interesting for biomedical applications. • Porosity is a function of hydrophobicity/hydrophilicity/molecular weight of phases. • The PNIPA/starch gel showed better morphology as scaffold for tissue engineering.

WOOD HEMICELLULOSE/CHITOSAN-BASED SEMI-INTERPENETRATING NETWORK HYDROGELS: MECHANICAL, SWELLING AND CONTROLLED DRUG RELEASE PROPERTIES

Directory of Open Access Journals (Sweden)

Muzaffer Ahmet Karaaslan

2010-04-01

Full Text Available The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose, and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the crosslinking agent. The hemicellulose isolated from aspen was analyzed for sugar content by HPLC, and its molecular weight distribution was determined by high performance size exclusion chromatography. Results revealed that hemicellulose had a broad molecular weight distribution with a fair amount of polymeric units, together with xylose, arabinose, and glucose. The effects of hemicellulose content on mechanical properties and swelling behavior of hydrogels were investigated. The semi-IPNs hydrogel structure was confirmed by FT-IR, X-ray study, and the ninhydrin assay method. X-ray analysis showed that higher hemicellulose contents yielded higher crystallinity. Mechanical properties were mainly dependent on the crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and were high at low pH values due to repulsion between similarly charged groups. In vitro release study of a model drug showed that these semi-IPN hydrogels could be used for controlled drug delivery into gastric fluid.

Potassium fulvate as co-interpenetrating agent during graft polymerization of acrylic acid from cellulose.

Science.gov (United States)

Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F; Essawy, Hisham A

2016-10-01

Grafting polymerization of acrylic acid onto cellulose in presence of potassium fulvate (KF) as a co-interpenetrating agent results enhanced water sorption compared to materials prepared similarly in its absence. The insertion of potassium fulvate (KF) did not affect the grafting process and is thought to proceed in parallel to the graft polymerization via intensive polycondensation reactions of its function groups (-COOH and OH) with COOH of the monomer and OH groups of cellulose. The combination of graft copolymerization and polycondensation reactions is assumed to produce interpenetrating network structure. Fourier transform infrared (FTIR) confirmed successful incorporation within the network structure which is an evidence for formation of interpenetrating network. The obtained structures showed homogeneous uniform surface as revealed by scanning electron microscopy (SEM). The obtained superabsorbent possessed high water absorbency 422 and 48.8g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced water retention even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high content of hydrophilic groups. The new superabsorbents proved to be efficient devices for controlled release of fertilizers which expands their use in agricultural applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Structures and interactions in collapsed hydrogels of thermoresponsive interpenetrating polymer networks

Czech Academy of Sciences Publication Activity Database

Hanyková, L.; Spěváček, Jiří; Radecki, M.; Zhigunov, Alexander; Šťastná, J.; Valentová, H.; Sedláková, Zdeňka

2015-01-01

Roč. 293, č. 3 (2015), s. 709-720 ISSN 0303-402X R&D Projects: GA ČR(CZ) GA13-23392S Institutional support: RVO:61389013 Keywords : temperature-induced volume phase transition * interpenetrating network * 1H NMR spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.890, year: 2015

Degradations and Rearrangement Reactions

Science.gov (United States)

Zhang, Jianbo

This section deals with recent reports concerning degradation and rearrangement reactions of free sugars as well as some glycosides. The transformations are classified in chemical and enzymatic ways. In addition, the Maillard reaction will be discussed as an example of degradation and rearrangement transformation and its application in current research in the fields of chemistry and biology.

Ion deceleration in interpenetrating plasma jets

International Nuclear Information System (INIS)

Renner, O.; Krousky, E.; Larroche, O.; Liska, R.

2010-01-01

Complete text of publication follows. Inertial and magnetic confinement fusion schemes involve collisions of high-temperature plasma jets and their interaction with solid surfaces (the so-called plasma-wall interaction, PWI). A fundamental understanding of the PWI effects requires a detailed characterization of the transient collisional phenomena occurring in the interaction region. In this paper we discuss a PWI experiment with double-foil Al/Mg targets fielded at the PALS laser system. An energetic plasma jet was created at the rear (non-irradiated) side of the 0.8-μm-thick Al foil exploded by the main laser beam (50-200 J, 0.44/1.315 μm, 0.25-0.3 ns, 16 W/cm 2 ). This plasma jet streamed towards the 2-μm-thick Mg foil, where the secondary plasma was created either by an auxiliary 5 J laser beam or by the main laser radiation transmitted through the Al foil, together with radiation and particles emitted from the Al foil. The environmental conditions in the plasma were diagnosed by means of high-resolution x-ray spectroscopy and temporally-resolved x-ray imaging. For the first time, the deceleration of the incident Al ions in the near-wall region was directly observed and quantitatively characterized from the Doppler shift of the J-satellite from the Al Lyα spectral group. The interaction scenario was numerically modeled by two concerted codes, namely, i) the Prague Arbitrary Lagrangian Eulerian 2-D code PALE, which solves the Lagrangian mesh distortions by smoothing and conservative remapping of conserved quantities, and ii) the multispecies 1.5-D code MULTIF which models the hydrodynamics of an arbitrary number of interpenetrating ion species in a single space dimension while assuming self-similar plasma expansion in the other directions, and taking into account detailed Coulombian collisional processes. PALE was used to model two counter-streaming Al/Mg plasma plumes until the beginning of their interaction, and the resulting plasma state was then used as

Self-assembled interpenetrating networks by orthogonal self assembly of surfactants and hydrogelators

NARCIS (Netherlands)

Brizard, Aurelie M.; Stuart, Marc C. A.; van Esch, Jan H.

2009-01-01

Interpenetrating networks (IPN) consist of two or more networks of different components which are entangled on a molecular scale and cannot be separated without breaking at least one of the networks. They are of great technological interest because they allow the blending of two or more otherwise

Chemical and Enzymatic Hydrolysis of Polyurethane/Polylactide Blends

Directory of Open Access Journals (Sweden)

Joanna Brzeska

2015-01-01

Full Text Available Polyether-esterurethanes containing synthetic poly[(R,S-3-hydroxybutyrate] (R,S-PHB and polyoxytetramethylenediol in soft segments and polyesterurethanes with poly(ε-caprolactone and poly[(R,S-3-hydroxybutyrate] were blended with poly([D,L]-lactide (PLA. The products were tested in terms of their oil and water absorption. Oil sorption tests of polyether-esterurethane revealed their higher response in comparison to polyesterurethanes. Blending of polyether-esterurethanes with PLA caused the increase of oil sorption. The highest water sorption was observed for blends of polyether-esterurethane, obtained with 10% of R,S-PHB in soft segments. The samples mass of polyurethanes and their blends were almost not changed after incubation in phosphate buffer and trypsin and lipase solutions. Nevertheless the molecular weight of polymers was significantly reduced after degradation. It was especially visible in case of incubation of samples in phosphate buffer what suggested the chemical hydrolysis of polymer chains. The changes of surface of polyurethanes and their blends, after incubation in both enzymatic solutions, indicated on enzymatic degradation, which had been started despite the lack of mass lost. Polyurethanes and their blends, contained more R,S-PHB in soft segments, were degraded faster.

Tribological Properties of AlSi12-Al₂O₃ Interpenetrating Composite Layers in Comparison with Unreinforced Matrix Alloy.

Science.gov (United States)

Dolata, Anna Janina

2017-09-06

Alumina-Aluminum composites with interpenetrating network structures are a new class of advanced materials with potentially better properties than composites reinforced by particles or fibers. Local casting reinforcement was proposed to take into account problems with the machinability of this type of materials and the shaping of the finished products. The centrifugal infiltration process fabricated composite castings in the form of locally reinforced shafts. The main objective of the research presented in this work was to compare the tribological properties (friction coefficient, wear resistance) of AlSi12/Al₂O₃ interpenetrating composite layers with unreinforced AlSi12 matrix areas. Profilometric tests enabled both quantitative and qualitative analyses of the wear trace that formed on investigated surfaces. It has been shown that interpenetrating composite layers are characterized by lower and more stable coefficients of friction (μ), as well as higher wear resistance than unreinforced matrix areas. At the present stage, the study confirmed that the tribological properties of the composite layers depend on the spatial structure of the ceramic reinforcement, and primarily the volume and size of alumina foam cells.

Life test of DMFC using poly(ethylene glycol)bis(carboxymethyl)ether plasticized PVA/PAMPS proton-conducting semi-IPNs

Energy Technology Data Exchange (ETDEWEB)

Qiao, Jinli [National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Central 5, Tsukuba, Ibaraki 305-8565 (Japan); New Energy Technology Research Center, Tongji University, Shanghai 201804 (China); Ikesaka, Shinya; Saito, Morihiro; Kuwano, Jun [Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, 12-1 Ichigayafunagawara-machi, Shinjuku-ku, Tokyo 162-0826 (Japan); Okada, Tatsuhiro [National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Central 5, Tsukuba, Ibaraki 305-8565 (Japan)

2007-08-15

A novel, low-cost proton-conducting semi-IPN (semi-interpenetrating polymer network) has been successfully prepared from PVA/PAMPS (poly(vinyl alcohol) and poly(2-acrylamindo-2-methyl-1-propanesulfonic acid))blends by incorporating poly(ethylene glycol)bis(carboxymethyl)ether (PEGBCME) as a novel plasticizer. Although, the polymer is based on a relatively low content of PAMPS as a component of ion conducting sites, the resulting semi-IPN exhibited high proton conductivity (0.1 S cm{sup -1}) at 25 C, which afforded a higher power density of 51 mW cm{sup -2} at 80 C. A striking feature is that a long-term initial performance is achieved with a 130 h of stable fuel cell operation in DMFC mode due to effectively suppressed methanol crossover. This is a new record for a fully hydrocarbon membrane in DMFC, seeing that the PVA-PAMPS proton-conducting semi-IPNs are made simply of aliphatic skeletons. (author)

Enzymatic degradation of aliphatic nitriles by Rhodococcus rhodochrous BX2, a versatile nitrile-degrading bacterium.

Science.gov (United States)

Fang, Shumei; An, Xuejiao; Liu, Hongyuan; Cheng, Yi; Hou, Ning; Feng, Lu; Huang, Xinning; Li, Chunyan

2015-06-01

Nitriles are common environmental pollutants, and their removal has attracted increasing attention. Microbial degradation is considered to be the most acceptable method for removal. In this work, we investigated the biodegradation of three aliphatic nitriles (acetonitrile, acrylonitrile and crotononitrile) by Rhodococcus rhodochrous BX2 and the expression of their corresponding metabolic enzymes. This organism can utilize all three aliphatic nitriles as sole carbon and nitrogen sources, resulting in the complete degradation of these compounds. The degradation kinetics were described using a first-order model. The degradation efficiency was ranked according to t1/2 as follows: acetonitrile>trans-crotononitrile>acrylonitrile>cis-crotononitrile. Only ammonia accumulated following the three nitriles degradation, while amides and carboxylic acids were transient and disappeared by the end of the assay. mRNA expression and enzyme activity indicated that the tested aliphatic nitriles were degraded via both the inducible NHase/amidase and the constitutive nitrilase pathways, with the former most likely preferred. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thermal degradation of glucosinolates in red cabbage

NARCIS (Netherlands)

Oerlemans, K.; Barrett, D.M.; Bosch Suades, C.; Verkerk, R.; Dekker, M.

2006-01-01

Thermal degradation of individual glucosinolates within the plant matrix was studied. Red cabbage samples were heated at different temperatures for various times. To rule out the influence of enzymatic breakdown and to focus entirely on the thermal degradation of glucosinolates, myrosinase was

Discovery of novel algae-degrading enzymes from marine bacteria

DEFF Research Database (Denmark)

Schultz-Johansen, Mikkel; Bech, Pernille Kjersgaard; Hennessy, Rosanna Catherine

Algal cell wall polysaccharides, and their derived oligosaccharides, display a range of health beneficial bioactive properties. Enzymes capable of degrading algal polysaccharides into oligosaccharides may be used to produce biomolecules with new functionalities for the food and pharma industry....... Some marine bacteria are specialized in degrading algal biomass and secrete enzymes that can decompose the complex algal cell wall polysaccharides. In order to identify such bacteria and enzymatic activities, we have used a combination of traditional cultivation and isolation methods, bioinformatics...... and functional screening. This resulted in the discovery of a novel marine bacterium which displays a large enzymatic potential for degradation of red algal polysaccharides e.g. agar and carrageenan. In addition, we searched metagenome sequence data and identified new enzyme candidates for degradation...

A simple semi-quantitative approach studying the in vivo degradation of regenerated silk fibroin scaffolds with different pore sizes.

Science.gov (United States)

Guo, Yongwei; Chen, Zhongchun; Wen, Jianchuan; Jia, Minghui; Shao, Zhengzhong; Zhao, Xia

2017-10-01

The biocompatibility and in vivo degradation rate of biomaterials represent critical control points in the long-term success of scaffolds for tissue restoration. In this study, new three-dimensional (3D) regenerated silk fibroin scaffolds (RSFs) were prepared by the freezing-defrosting procedure, and then were implanted beneath the dorsal skin of rats. This study aims to develop a kinetic semi-quantitative approach to assess in vivo degradation rate and biocompatibility of this kind of RSFs with different pore sizes for the first time, and to evaluate the relationship between the biodegradation and tissue responses by measuring the thickness of residual scaffolds, fibrous capsules and infiltrated tissues through integrated techniques of histology, optical imaging and image analysis. Our results showed that scaffolds with both pore sizes (74.35±10.84μm and 139.23±44.93μm, respectively) were well tolerated by host animals and pore size was found to be the rate limiting factor to the biodegradation in the subcutaneous implantation model. In addition, the biodegradation of RSFs was inflammation-mediated to a certain degree and fibroblasts may play a critical role in this process. Overall, such semi-quantitative approach was demonstrated to be a simple and effective method to assess the in vivo degradation rate, and the prepared RSFs were presented to have promising potential in tissue engineering applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Soft hydrogels interpenetrating silicone – a polymer network for drug releasing medical devices

DEFF Research Database (Denmark)

Steffensen, Søren Langer; Merete H., Vestergaard,; Møller, Eva Horn

2016-01-01

such a sophisticated material by forming an interpenetrating polymer network (IPN) material through modification of silicone elastomers with a poly(2-hydroxyethyl methacrylate) (PHEMA)-based hydrogel. IPN materials with a PHEMA content in the range of 13%–38% (w/w) were synthesized by using carbon dioxide...

Wood hemicellulose/chitosan-based semi-interpenetrating network hydrogels : mechanical swelling and controlled drug release properties

Science.gov (United States)

Ahmet M. Karaaslan; Mandla A. Tshabalala; Gisela Buschle-Diller

2010-01-01

The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose, and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the...

Method of phorbol ester degradation in Jatropha curcas L. seed cake using rice bran lipase.

Science.gov (United States)

Hidayat, Chusnul; Hastuti, Pudji; Wardhani, Avita Kusuma; Nadia, Lana Santika

2014-03-01

A novel enzymatic degradation of phorbol esters (PE) in the jatropha seed cake was developed using lipase. Cihera rice bran lipase had the highest ability to hydrolyze PE, and reduced PE to a safe level after 8 h of incubation. Enzymatic degradation may be a promising method for PE degradation. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya

Science.gov (United States)

Mganga, K. Z.; Musimba, N. K. R.; Nyariki, D. M.

2015-12-01

Drylands occupy more than 80 % of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya.

Science.gov (United States)

Mganga, K Z; Musimba, N K R; Nyariki, D M

2015-12-01

Drylands occupy more than 80% of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

Solar assisted alkali pretreatment of garden biomass: Effects on lignocellulose degradation, enzymatic hydrolysis, crystallinity and ultra-structural changes in lignocellulose

International Nuclear Information System (INIS)

Gabhane, Jagdish; William, S.P.M. Prince; Vaidya, Atul N.; Das, Sera; Wate, Satish R.

2015-01-01

Highlights: • SAAP is an efficient and economic means of pretreatment. • SAAP was found to be efficient in lignin and hemicellulose removal. • SAAP enhanced the enzymatic hydrolysis. • FTIR, XRD and SEM provided vivid understanding about the mode of action of SAAP. • Mass balance closer of 98% for pretreated GB confirmed the reliability of SAAP. - Abstract: A comprehensive study was carried out to assess the effectiveness of solar assisted alkali pretreatment (SAAP) on garden biomass (GB). The pretreatment efficiency was assessed based on lignocellulose degradation, conversion of cellulose into reducing sugars, changes in the ultra-structure and functional groups of lignocellulose and impact on the crystallinity of cellulose, etc. SAAP was found to be efficient for the removal of lignin and hemicellulose that facilitated enzymatic hydrolysis of cellulose. FTIR and XRD studies provided details on the effectiveness of SAAP on lignocellulosic moiety and crystallinity of cellulose. Scanning electron microscopic analysis showed ultra-structural disturbances in the microfibrils of GB as a result of pretreatment. The mass balance closer of 97.87% after pretreatment confirmed the reliability of SAAP pretreatment. Based on the results, it is concluded that SAAP is not only an efficient means of pretreatment but also economical as it involved no energy expenditure for heat generation during pretreatment

Preparation and wear behavior of polymer matrix composites with an interpenetrating network structure derived from natural sponge

International Nuclear Information System (INIS)

Wang Tianchi; Zhou Tianle; Xiong Dangsheng

2010-01-01

Natural sponge was used as a template to produce carbon/epoxy resin and (carbon+silicon carbide)/epoxy resin composites with interpenetrating network structures. Carbon with a network structure was first obtained by pyrolysis of the natural sponge. The composites were then obtained by injecting epoxy resin and silicone resin into the carbon. Their microstructures and wear properties were analyzed. The results show that the natural structure of sponge controlled the interpenetrating network structures of the composites. The netlike carbon in the composites reduced the wear rate of the epoxy resin. Compared with the carbon/epoxy resin composite, the (carbon+silicon carbide)/epoxy resin composite shows better wear resistance.

Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment.

Science.gov (United States)

Saygın, Selen Deviren; Basaran, Mustafa; Ozcan, Ali Ugur; Dolarslan, Melda; Timur, Ozgur Burhan; Yilman, F Ebru; Erpul, Gunay

2011-09-01

Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10 cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed.

Enzyme-catalyzed degradation of biodegradable polymers derived from trimethylene carbonate and glycolide by lipases from Candida antarctica and Hog pancreas.

Science.gov (United States)

Liu, Feng; Yang, Jian; Fan, Zhongyong; Li, Suming; Kasperczyk, Janusz; Dobrzynski, Piotr

2012-01-01

Enzyme-catalyzed degradation of poly(trimethylene carbonate) homo-polymer (PTMC) and poly(trimethylene carbonate-co-glycolide) co-polymer (PTGA) was investigated in the presence of lipases from Candida antarctica and Hog pancreas. Degradation was monitored by gravimetry, size-exclusion chromatography (SEC), nuclear magnetic resonance (NMR), tensiometry and environmental scanning electron microscopy (ESEM). PTMC can be rapidly degraded by Candida antarctica lipase with 98% mass loss after 9 days, while degradation by Hog pancreas lipase leads to 27% mass loss. Introduction of 16% glycolide units in PTMC chains strongly affects the enzymatic degradation. Hog pancreas lipase becomes more effective to PTGA co-polymer with a mass loss of 58% after 9 days, while Candida antarctica lipase seems not able to degrade PTGA. Bimodal molecular weight distributions are observed during enzymatic degradation of both PTMC and PTGA, which can be assigned to the fact that the surface is largely degraded while the internal part remains intact. The composition of the PTGA co-polymer remains constant, and ESEM shows that the polymers are homogeneously eroded during enzymatic degradation. Contact angle measurements confirm the enzymatic degradation mechanism, i.e., enzyme adsorption on the polymer surface followed by enzyme-catalyzed chain cleavage.

HYDROLYSIS OF AGRICULTURAL BIOMASS BY COMBINED PRETREATMENT AND ENZYMATIC METHODS IN ORDER TO PRODUCE BIOFUELS (ETHANOL, BIOGAS

Directory of Open Access Journals (Sweden)

STEFANA JURCOANE

2009-05-01

Full Text Available The use of energy crops (maize straw, wheat straw, barley straw etc. as substrate for renewable energy production (e.g. biogas is more efficient when it is degraded by different hydrolysis methods. However, fibers contained inside energy crops (e.g. cellulose and hemicellulose are only hardly and slowly degraded by anaerobic bacteria. The slow degradation of these substances can decrease the methane yields of agricultural biogas plants.In the present study, we investigated the efficiency of combined pretreatment (different concentrations H2SO4 + 30 minutes at 1210C followed to enzymatic hydrolysis. Testing different concentration of H2SO4, good results were obtained for maize whole crop when we used combined pretreatment (3% H2SO4 + 30 minutes at 1210C followed to enzymatic hydrolysis (3.9 fold higher and for Gavott Maize Straw when we used combined pretreatment (2% H2SO4 + 30 minutes at 1210C followed to enzymatic hydrolysis (3.6 fold higher comparing with untreated samples.

Synthesis and characterization of sulfonic acid membranes based on interpenetrating polymer networks for application in fuel cells; Sintese e caracterizacao de membranas sulfonadas baseadas em redes polimericas interpenetrantes para aplicacao em celulas a combustivel

Energy Technology Data Exchange (ETDEWEB)

Blanco, Lyzed Toloza; Loureiro, Felipe A.M.; Rocco, Ana Maria [Grupo de Materiais Condutores e Energia, Escola de Quimica, Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)], e-mail: amrocco@eq.ufrj.br; Pereira, Robson Pacheco [Instituto de Ciencias Exatas, Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil)

2011-07-01

In the present work, the synthesis and characterization of sulfonic membranes based on interpenetrating polymer networks (IPN). In order to obtain such systems, the diglycidyl ether of bisphenol A (DGEBA) was polymerized in presence of polyethyleneimine (PEI). These membranes were submitted to sulfonation reactions, originating IPN-SO{sub 3}H membranes. The characterization by FTIR evidenced the formation of a Semi-IPN structure, while sulfonation reactions resulted in systems containing -SO{sub 3}H groups covalently bonded to the chains. The membranes exhibited water retention up to 200 degree C, in a temperature range sufficient for application in PEMFC under hydration. (author)

Highly Efficient Cooperative Catalysis by Co ^III (Porphyrin) Pairs in Interpenetrating Metal-Organic Frameworks

Energy Technology Data Exchange (ETDEWEB)

Lin, Zekai; Zhang, Zhi-Ming; Chen, Yu-Sheng; Lin, Wenbin (UC); (Xiamen)

2016-12-02

A series of porous twofold interpenetrated In-Co^III(porphyrin) metal–organic frameworks (MOFs) were constructed by in situ metalation of porphyrin bridging ligands and used as efficient cooperative catalysts for the hydration of terminal alkynes. The twofold interpenetrating structure brings adjacent Co^III(porphyrins) in the two networks parallel to each other with a distance of about 8.8 Å, an ideal distance for the simultaneous activation of both substrates in alkyne hydration reactions. As a result, the In-Co^III(porphyrin) MOFs exhibit much higher (up to 38 times) catalytic activity than either homogeneous catalysts or MOF controls with isolated Co^III(porphyrin) centers, thus highlighting the potential application of MOFs in cooperative catalysis.

Use of carbon isotope analysis to understand semi-arid erosion dynamics and long-term semi-arid land degradation.

Science.gov (United States)

Turnbull, Laura; Brazier, Richard E; Wainwright, John; Dixon, Liz; Bol, Roland

2008-06-01

Many semi-arid areas worldwide are becoming degraded, in the form of C(4) grasslands being replaced by C(3) shrublands, which causes an increase in surface runoff and erosion, and altered nutrient cycling, which may affect global biogeochemical cycling. The prevention or control of vegetation transitions is hindered by a lack of understanding of their temporal and spatial dynamics, particularly in terms of interactions between biotic and abiotic processes. This research investigates (1) the effects of soil erosion on the delta(13)C values of soil organic matter (SOM) throughout the soil profile and its implications for reconstructing vegetation change using carbon-isotope analysis and (2) the spatial properties of erosion over a grass-shrub transition to increase understanding of biotic-abiotic interactions by using delta(13)C signals of eroded material as a sediment tracer. Results demonstrate that the soils over grass-shrub transitions are not in steady state. A complex interplay of factors determines the input of SOM to the surface horizon of the soil and its subsequent retention and turnover through the soil profile. A positive correlation between event runoff and delta(13)C signatures of eroded sediment was found in all plots. This indicates that the delta(13)C signatures of eroded sediment may provide a means of distinguishing between changes in erosion dynamics over runoff events of different magnitudes and over different vegetation types. The development of this technique using delta(13)C signatures of eroded sediment provides a new means of furthering existing understanding of erosion dynamics over vegetation transitions. This is critical in terms of understanding biotic-abiotic feedbacks and the evolution of areas subject to vegetation change in semi-arid environments. John Wiley & Sons, Ltd

PSA-alpha-2-macroglobulin complex is enzymatically active in the serum of patients with advanced prostate cancer and can degrade circulating peptide hormones.

Science.gov (United States)

Kostova, Maya B; Brennen, William Nathaniel; Lopez, David; Anthony, Lizamma; Wang, Hao; Platz, Elizabeth; Denmeade, Samuel R

2018-08-01

Prostate cancer cells produce high levels of the serine protease Prostate-Specific Antigen (PSA). PSA is enzymatically active in the tumor microenvironment but is presumed to be enzymatically inactive in the blood due to complex formation with serum protease inhibitors α-1-antichymotrypsin and α-2-macroglobulin (A2M). PSA-A2M complexes cannot be measured by standard ELISA assays and are also rapidly cleared from the circulation. Thus the exact magnitude of PSA production by prostate cancer cells is not easily measured. The PSA complexed to A2M is unable to cleave proteins but maintains the ability to cleave small peptide substrates. Thus, in advanced prostate cancer, sufficient PSA-A2M may be in circulation to effect total A2M levels, levels of cytokines bound to A2M and hydrolyze small circulating peptide hormones. Total A2M levels in men with advanced prostate cancer and PSA levels above 1000 ng/mL were measured by ELISA and compared to controls. Additional ELISA assays were used to measure levels of IL-6 and TGF-beta which can bind to A2M. The ability of PSA-A2M complexes to hydrolyze protein and peptide substrates was analyzed ± PSA inhibitor. Enzymatic activity of PSA-A2M in serum of men with high PSA levels was also assayed. Serum A2M levels are inversely correlated with PSA levels in men with advanced prostate cancer. Il-6 Levels are significantly elevated in men with PSA >1000 ng/mL compared to controls with PSA PSA-A2M complex in serum of men with PSA levels >1000 ng/mL can hydrolyze small fluorescently labeled peptide substrates but not large proteins that are PSA substrates. PSA can hydrolyze small peptide hormones like PTHrP and osteocalcin. PSA complexed to A2M retains the ability to degrade PTHrP. In advanced prostate cancer with PSA levels >1000 ng/mL, sufficient PSA-A2M is present in circulation to produce enzymatic activity against circulating small peptide hormones. Sufficient PSA is produced in advanced prostate cancer to alter

The cellulases and their application in degrading agro-industrial waste

Directory of Open Access Journals (Sweden)

Wolfgang H. Schwarz

2002-01-01

Full Text Available A huge amount of lignocellulosic biomass is available which can be used to produce storable energy and basic material for the chemical industry. Its use is especially beneficial for a country's economy if it is waste material, which can be obtained at almost no cost and which presents an environmental burden. However, the polysaccharides present in biomass are difficult to degrade due to their heterogeneity and crystalline structure. This article addresses the enzymatic hydrolysis of cellulose by its natural degraders, the anaerobic bacteria. The difficulties of cellulose digestion are explained and the strategies used by the hydrolytic enzymes and enzyme systems, allowing for efficient degradation. The multitude of enzymes is uniform in having an identical chemical specificity, but differs in each component's action mode. Only by combining this with binding modules can efficient hydrolysis be performed. The variation of modular structures within a single enzyme family is an example of enzymatic activity's evolutionary diversification. A model for hydrolytically degrading natural cellulose is presented, but much more research has to be done to explain and describe the process on the molecular level, and to optimize an industrial enzymatic cellulose hydrolysis process.

Radiation pretreatments of cellulose materials for the enhancement of enzymatic hydrolysis

International Nuclear Information System (INIS)

Ait Si Mamar, S.; Hadjadj, A.

1990-01-01

The conversion of wheat straw agricultural cellulosic wastes to reducing sugars and glucose has been studied by pretreatments by acid hydrolysis and gamma radiolysis over the dose 0-2 MGy. The pretreatment of cellulosic wastes by gamma radiolysis in the presence of sulfuric acid solution shows that the reducing sugars yield increases with the irradiation dose. The effect of radiation degradation on cellulosic wastes between 0.1 MGy and 2 MGy shows the glucose and reducing sugars yields after enzymatic hydrolysis by cellulase vary with the dose. In the relatively low dose range, up to about 0.5 MGy, the reducing sugars yields vary slightly. For an acid hydrolysis followed by radiation at dose range below 0.5 MGy the reducing sugars yields are practically insensitive to radiation. On the other hand, the pretreatment by radiation in higher dose range from 0.5 to 2 MGy followed by enzymatic hydrolysis is effective for the conversion of cellulosic wastes into glucose. The radiation induced degradation of cellulose into glucose depends on the type of acid hydrolysis and on the enzymatic hydrolysis time by cellulase. Pre-irradiation in air is more effective than in acid solution. (author)

Radiation pretreatments of cellulose materials for the enhancement of enzymatic hydrolysis

Science.gov (United States)

Mamar, S. Ait Si; Hadjadj, A.

The conversion of wheat straw agricultural cellulosic wastes to reduning sugars and glucose has been studied by pretreatments by acid hydrolysis and gamma radiolysis over the dose 0-2 MGy. The pretreatment of cellulosic wastes by gamma radiolysis in the presence of sulfuric acid solution shows that the reducing sugars yield increases with the irradiation dose. The effect of radiation degradation on cellulosic wastes between 0.1 MGy and 2 MGy shows the glucose and reducing sugars yields after enzymatic hydrolysis by cellulase vary with the dose. In the relatively low dose range, up to about 0.5 MGy, the reducing sugars yields vary slightly. For an acid hydrolysis followed by radiation at dose range below 0.5 MGy the reducing sugars yields are practically insensitive to radiation. On the other hand, the pretreatment by radiation in higher dose range from 0.5 to 2 MGy followed by enzymatic hydrolysis is effective for the conversion of cellulosic wastes into glucose. The radiation induced degradation of cellulose into glucose depends on the type of acid hydrolysis and on the enzymatic hydrolysis time by cellulase. Pre-irradiation in air is more effective than in acid solution.

Thomson scattering measurements of ion interpenetration in cylindrically converging, supersonic magnetized plasma flows

Science.gov (United States)

Swadling, George

2015-11-01

Ion interpenetration driven by high velocity plasma collisions is an important phenomenon in high energy density environments such as the interiors of ICF vacuum hohlraums and fast z-pinches. The presence of magnetic fields frozen into these colliding flows further complicates the interaction dynamics. This talk focuses on an experimental investigation of ion interpenetration in collisions between cylindrically convergent, supersonic, magnetized flows (M ~10, Vflow ~ 100km/s, ni ~ 1017cm-3) . The flows used in this study were plasma ablation streams produced by tungsten wire array z-pinches, driven by the 1.4MA, 240ns Magpie facility at Imperial College, and diagnosed using a combination of optical Thomson scattering, Faraday rotation and interferometry. Optical Thomson scattering (TS) provides time-resolved measurements of local flow velocity and plasma temperature across multiple (7 to 14) spatial positions. TS spectra are recorded simultaneously from multiple directions with respect to the probing beam, resulting in separate measurements of the rates of transverse diffusion and slowing-down of the ion velocity distribution. The measurements demonstrate flow interpenetration through the array axis at early time, and also show an axial deflection of the ions towards the anode. This deflection is induced by a toroidal magnetic field (~ 10T), frozen into the plasma that accumulates near the axis. Measurements obtained later in time show a change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streams, and rapid radial collapse of the magnetized plasma column. The quantitative nature of the spatial profiles of the density, flow velocities and ion temperatures measured in these experiments will allow detailed verification of MHD and PIC codes used by the HEDP community. Work Supported by EPSRC (Grant No. EP/G001324/1), DOE (Cooperative Agreement Nos. DE-F03-02NA00057 & DE-SC-0001063) & Sandia National

Poly(ethylene oxide monomethyl ether)- block-poly(propylene succinate) Nanoparticles: Synthesis and Characterization, Enzymatic and Cellular Degradation, Micellar Solubilization of Paclitaxel, and in Vitro and in Vivo Evaluation.

Science.gov (United States)

Jäger, Alessandro; Jäger, Eliézer; Syrová, Zdeňka; Mazel, Tomas; Kováčik, Lubomír; Raška, Ivan; Höcherl, Anita; Kučka, Jan; Konefal, Rafal; Humajova, Jana; Poučková, Pavla; Štěpánek, Petr; Hrubý, Martin

2018-04-11

Polyester-based nanostructures are widely studied as drug-delivery systems due to their biocompatibility and biodegradability. They are already used in the clinic. In this work, we describe a new and simple biodegradable and biocompatible system as the Food and Drug Administration approved polyesters (poly-ε-caprolactone, polylactic acid, and poly(lactic- co-glycolic acid)) for the delivery of the anticancer drug paclitaxel (PTX) as a model drug. A hydrophobic polyester, poly(propylene succinate) (PPS), was prepared from a nontoxic alcohol (propylene glycol) and monomer from the Krebs's cycle (succinic acid) in two steps via esterification and melt polycondensation. Furthermore, their amphiphilic block copolyester, poly(ethylene oxide monomethyl ether)- block-poly(propylene succinate) (mPEO- b-PPS), was prepared by three steps via esterification followed by melt polycondensation and the addition of mPEO to the PPS macromolecules. Analysis of the in vitro cellular behavior of the prepared nanoparticle carriers (NPs) (enzymatic degradation, uptake, localization, and fluorescence resonance energy-transfer pair degradation studies) was performed by fluorescence studies. PTX was loaded to the NPs of variable sizes (30, 70, and 150 nm), and their in vitro release was evaluated in different cell models and compared with commercial PTX formulations. The mPEO- b-PPS copolymer analysis displays glass transition temperature hydrolysis during transport in bloodstream, and simultaneous enzymatic degradability after uptake into the cells. The detailed cytotoxicity in vitro and in vivo tumor efficacy studies have shown the superior efficacy of the NPs compared with PTX and PTX commercial formulations.

Effect of semi-permeable cover system on the bacterial diversity during sewage sludge composting.

Science.gov (United States)

Robledo-Mahón, Tatiana; Aranda, Elisabet; Pesciaroli, Chiara; Rodríguez-Calvo, Alfonso; Silva-Castro, Gloria Andrea; González-López, Jesús; Calvo, Concepción

2018-06-01

Sewage sludge composting is a profitable process economically viable and environmentally friendly. In despite of there are several kind of composting types, the use of combined system of semipermeable cover film and aeration air-floor is widely developed at industrial scale. However, the knowledge of the linkages between microbial communities structure, enzyme activities and physico-chemical factors under these conditions it has been poorly explored. Thus, the aim of this study was to investigate the bacterial dynamic and community structure using next generation sequencing coupled to analyses of microbial enzymatic activity and culturable dependent techniques in a full-scale real composting plant. Sewage sludge composting process was conducted using a semi-permeable Gore-tex cover, in combination with an air-insufflation system. The highest values of enzymatic activities such as dehydrogenase, protease and arylsulphatase were detected in the first 5 days of composting; suggesting that during this period of time a greater degrading activity of organic matter took place. Culturable bacteria identified were in agreement with the bacteria found by massive sequencing technologies. The greatest bacterial diversity was detected between days 15 and 30, with Actinomycetales and Bacillales being the predominant orders at the beginning and end of the process. Bacillus was the most representative genus during all the process. A strong correlation between abiotic factors as total organic content and organic matter and enzymatic activities such as dehydrogenase, alkaline phosphatase, and ß-glucosidase activity was found. Bacterial diversity was strongly influenced by the stage of the process, community-structure change was concomitant with a temperature rise, rendering favorable conditions to stimulate microbial activity and facilitate the change in the microbial community linked to the degradation process. Moreover, results obtained confirmed that the use of semipermeable

Enhancement of enzymatic saccharification of Eucalyptus globulus: steam explosion versus steam treatment.

Science.gov (United States)

Martin-Sampedro, Raquel; Revilla, Esteban; Villar, Juan C; Eugenio, Maria E

2014-09-01

Steam explosion and steam pre-treatment have proved capable of enhancing enzymatic saccharification of lignocellulosic materials. However, until now, these methods had not been compared under the same operational conditions and using the same raw material. Both pre-treatments lead to increased yields in the saccharification of Eucalyptus globulus; but results have been better with steam pre-treatments, despite the more accessible surface of exploded samples. The reason for this finding could be enzymatic inhibition: steam explosion causes a more extensive extraction of hemicelluloses and releases a greater amount of degradation products which can inhibit enzymatic action. Enzymatic inhibition is also dependent on the amount and chemical structure of lignin, which was also a contributing factor to the lower enzymatic yields obtained with the most severe pre-treatment. Thus, the highest yields (46.7% glucose and 73.4% xylose yields) were obtained after two cycle of steam treatment, of 5 and 3 min, at 183°C. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enzymatic Digestion of Chronic Wasting Disease Prions Bound to Soil

Science.gov (United States)

SAUNDERS, SAMUEL E.; BARTZ, JASON C.; VERCAUTEREN, KURT C.; BARTELT-HUNT, SHANNON L.

2010-01-01

Chronic wasting disease (CWD) and sheep scrapie can be transmitted via indirect environmental routes, and it is known that soil can serve as a reservoir of prion infectivity. Given the strong interaction between the prion protein (PrP) and soil, we hypothesized that binding to soil enhances prion resistance to enzymatic digestion, thereby facilitating prion longevity in the environment and providing protection from host degradation. We characterized the performance of a commercially available subtilisin enzyme, the Prionzyme, to degrade soil-bound and unbound CWD and HY TME PrP as a function of pH, temperature, and treatment time. The subtilisin enzyme effectively degraded PrP adsorbed to a wide range of soils and soil minerals below the limits of detection. Signal loss occurred rapidly at high pH (12.5) and within 7 d under conditions representative of the natural environment (pH 7.4, 22°C). We observed no apparent difference in enzyme effectiveness between bound and unbound CWD PrP. Our results show that although adsorbed prions do retain relative resistance to enzymatic digestion compared with other brain homogenate proteins, they can be effectively degraded when bound to soil. Our results also suggest a topical application of a subtilisin enzyme solution may be an effective decontamination method to limit disease transmission via environmental ‘hot spots’ of prion infectivity. PMID:20450190

Preparation and Properties of a Novel Semi-IPN Slow-Release Fertilizer with the Function of Water Retention.

Science.gov (United States)

Xiang, Yang; Ru, Xudong; Shi, Jinguo; Song, Jiang; Zhao, Haidong; Liu, Yaqing; Guo, Dongdong; Lu, Xin

2017-12-20

A new semi-interpenetrating polymer network (semi-IPN) slow-release fertilizer (SISRF) with water absorbency, based on the kaolin-g-poly(acrylic acid-co-acrylic amide) (kaolin-g-P(AA-co-AM)) network and linear urea-formaldehyde oligomers (UF), was prepared by solution polymerization. Nutrients phosphorus and potassium were supplied by adding dipotassium hydrogen phosphate during the preparation process. The structure and properties of SISRF were characterized by various characterization methods. SISRF showed excellent water absorbency of 68 g g -1 in tap water. The slow-release behavior of nutrients and water-retention capacity of SISRF were also measured. Meanwhile, the swelling kinetics was well described by a pseudo-second-order kinetics model. Results suggested the formation of SISRF with simultaneously good slow-release and water-retention capacity, which was expected to apply in modern agriculture and horticulture.

Interpenetrating polymer networks from acetylene terminated materials

Science.gov (United States)

Connell, J. W.; Hergenrother, P. M.

1989-01-01

As part of a program to develop high temperature/high performance structural resins for aerospace applications, the chemistry and properties of a novel class of interpenetrating polymer networks (IPNs) were investigated. These IPNs consist of a simple diacetylenic compound (aspartimide) blended with an acetylene terminated arylene ether oligomer. Various compositional blends were prepared and thermally cured to evaluate the effect of crosslink density on resin properties. The cured IPNs exhibited glass transition temperatures ranging from 197 to 254 C depending upon the composition and cure temperature. The solvent resistance, fracture toughness and coefficient of thermal expansion of the cured blends were related to the crosslink density. Isothermal aging of neat resin moldings, adhesive and composite specimens showed a postcure effect which resulted in improved elevated temperature properties. The chemistry, physical and mechanical properties of these materials will be discussed.

Radiation pretreatments of cellulose materials for the enhancement of enzymatic hydrolysis

International Nuclear Information System (INIS)

Ardica, S.; Calderaro, E.; Cappadona, C.

1985-01-01

The effect of γ-ray pre-irradiation of cellulose materials such as wood chips, paper, grain straw, hay and kapok on glucose production on enzymatic hydrolysis by cellulase has been investigated. These materials have been irradiated in air, water and acetate buffer solution over the dose range 10 3 to 4 x 10 6 Gy. In the relatively low dose range, up to about 5 x 10 5 Gy, the glucose yields after enzymatic hydrolysis are practically insensitive to radiation. At higher dose levels, up to 1.7 to 2 x 10 6 Gy, the pre-irradiation becomes very effective on enzymatic cellulose conversion. It has been found that the radiation-induced degradation of cellulose into low molecular weight polysaccharides is dependent on the nature and chemical composition of the cellulose materials and on the radiation environmental conditions. Further increases of dose causes radiation-induced structural modifications in polysaccharides previously produced, which can lead to a decrease in glucose production by enzymatic hydrolysis. (author)

Degradation of Collagen Increases Nitrogen Solubilisation During Enzymatic Hydrolysis of Fleshing Meat

NARCIS (Netherlands)

Anzani, Cecilia; Prandi, Barbara; Tedeschi, Tullia; Baldinelli, Chiara; Sorlini, Giovanni; Wierenga, Peter A.; Dossena, Arnaldo; Sforza, Stefano

2017-01-01

Abstract: The meat portion directly attached to bovine hides (fleshing meat) is a by-product of leather industry that is a potential new source of proteins. In literature different enzymatic and chemical methods have been proposed to hydrolyze and solubilize fleshing meat. Enzyme hydrolysis is

Identification of the key ecological factors influencing vegetation degradation in semi-arid agro-pastoral ecotone considering spatial scales

Science.gov (United States)

Peng, Yu; Wang, Qinghui; Fan, Min

2017-11-01

When assessing re-vegetation project performance and optimizing land management, identification of the key ecological factors inducing vegetation degradation has crucial implications. Rainfall, temperature, elevation, slope, aspect, land use type, and human disturbance are ecological factors affecting the status of vegetation index. However, at different spatial scales, the key factors may vary. Using Helin County, Inner-Mongolia, China as the study site and combining remote sensing image interpretation, field surveying, and mathematical methods, this study assesses key ecological factors affecting vegetation degradation under different spatial scales in a semi-arid agro-pastoral ecotone. It indicates that the key factors are different at various spatial scales. Elevation, rainfall, and temperature are identified as crucial for all spatial extents. Elevation, rainfall and human disturbance are key factors for small-scale quadrats of 300 m × 300 m and 600 m × 600 m, temperature and land use type are key factors for a medium-scale quadrat of 1 km × 1 km, and rainfall, temperature, and land use are key factors for large-scale quadrats of 2 km × 2 km and 5 km × 5 km. For this region, human disturbance is not the key factor for vegetation degradation across spatial scales. It is necessary to consider spatial scale for the identification of key factors determining vegetation characteristics. The eco-restoration programs at various spatial scales should identify key influencing factors according their scales so as to take effective measurements. The new understanding obtained in this study may help to explore the forces which driving vegetation degradation in the degraded regions in the world.

Degradation and Moisture Absorption Study of Potato-starch Linear ...

African Journals Online (AJOL)

Composite of linear low density polyethylene (LLDPE) and potato-starch was produced and subjected to degradation studies with the agencies of enzymes, exposure to weather and immersion in water. Enzymatic hydrolysis degraded the matrix to an extent greater than 40% loss in strength and about 20% loss in ...

Study of SiO2/PMMA/CE tri-component interpenetrating polymer network composites

International Nuclear Information System (INIS)

Wang Junlong; Wang Chuang; Jiao Gengsheng; Wang Qiuya

2010-01-01

A technology of conjugated tri-component interpenetrating polymer networks was applied to synthesize a nano-SiO 2 /polymethylmethacrylate (PMMA)/cyanate (CE) composite through an asynchronous synthesis way. The microstructure of the composite was characterized using infrared spectroscopy (IR) and transmission electron microscopy (TEM). The mechanical properties were measured in German-made DL-1000B and XCL-40 universal material test machines, respectively. Results showed that both the impact strength and the flexural strength were in the optimum status when 3% SiO 2 /PMMA/CE was chosen as a sample with the PMMA/CE ratio of 20/80. Compared with the strengths of pure cyanate, those of the composite were raised by 137.28% and 31.29%, respectively. When 3% nano-SiO 2 was added, the impact strength was increased by 29.96% and the flexural strength by 20.05%, compared with the strengths of polymers without SiO 2 . Analysis and measurements by IR and TEM indicated that no chemical reactions took place among components in the composite. The interpenetration of the conjugated tri-component improved the loading capacity of the polymer, hence the toughness enhancement of cyanate.

Nanosilver: A Catalyst in Enzymatic Hydrolysis of Starch

Directory of Open Access Journals (Sweden)

Falkowska Marta

2014-09-01

Full Text Available Silver nanoparticles are widely used, because of their antimicrobial properties. In this paper, the rate of starch digestion in the presence of nanocatalyst was compared with the rate of reaction without nanosilver. The rate of enzymatic degradation of starch was found to be increased in the presence of silver nanoparticles. It is considered that α-amylase was immobilized onto the surface of nanoparticles.

Synthesis and properties of hemicelluloses-based semi-IPN hydrogels.

Science.gov (United States)

Peng, Feng; Guan, Ying; Zhang, Bing; Bian, Jing; Ren, Jun-Li; Yao, Chun-Li; Sun, Run-Cang

2014-04-01

Hemicelluloses were extracted from holocellulose of bamboo by alkaline treatment. The phosphorylated poly(vinyl alcohol) (P-PVA) samples with various substitution degrees were prepared through the esterification of PVA and phosphoric acid. A series of hydrogels of semi-interpenetrating polymeric networks (semi-IPN) composed of hemicelluloses-g-poly(acrylic acid) (HM-g-PAA) and the phosphorylated poly(vinyl alcohol) (P-PVA) were prepared by radical polymerization using potassium persulphate (KPS) as initiator. The HM-g-PAA networks were crosslinked by N,N-methylenebisacrylamide (MBA) as a crosslinking agent in the presence of linear P-PVA. FT-IR results confirmed that the hydrogels comprised a porous crosslink structure of P-PVA and HM with side chains that carried carboxylate and phosphorylate groups. SEM observations indicated that the incorporation of P-PVA induced highly porous structure, and P-PVA was uniformly dispersed in the polymeric network. The interior network structures of the semi-IPN matrix became more porous with increasing P-PVA. The TGA results showed that the thermo-decomposing temperature and thermal stability were increased effectively for intruding the chain of P-PVA. The maximum equilibrium swelling ratio of hydrogels in distilled water and 0.9 wt% sodium chloride solutions was up to 1085 g g(-1) and 87 g g(-1), respectively. The compressive strength increased with increasing the MBA/HM and P-PVA/HM ratios, and decreased with the increment of AA/HM ratio. Copyright © 2014 Elsevier B.V. All rights reserved.

Enzymatic Hydrolysis of Oleuropein from Olea europea (Olive Leaf Extract and Antioxidant Activities

Directory of Open Access Journals (Sweden)

Jiao-Jiao Yuan

2015-02-01

Full Text Available Oleuropein (OE, the main polyphenol in olive leaf extract, is likely to decompose into hydroxytyrosol (HT and elenolic acid under the action of light, acid, base, high temperature. In the enzymatic process, the content of OE in olive leaf extract and enzyme are key factors that affect the yield of HT. A selective enzyme was screened from among 10 enzymes with a high OE degradation rate. A single factor (pH, temperature, time, enzyme quantity optimization process and a Box-Behnken design were studied for the enzymatic hydrolysis of 81.04% OE olive leaf extract. Additionally, enzymatic hydrolysis results with different substrates (38.6% and 81.04% OE were compared and the DPPH antioxidant properties were also evaluated. The result showed that the performance of hydrolysis treatments was best using hemicellulase as a bio-catalyst, and the high purity of OE in olive extract was beneficial to biotransform OE into HT. The optimal enzymatic conditions for achieving a maximal yield of HT content obtained by the regression were as follows: pH 5, temperature 55 °C and enzyme quantity 55 mg. The experimental result was 11.31% ± 0.15%, and the degradation rate of OE was 98.54%. From the present investigation of the antioxidant activity determined by the DPPH method, the phenol content and radical scavenging effect were both decreased after enzymatic hydrolysis by hemicellulase. However, a high antioxidant activity of the ethyl acetate extract enzymatic hydrolysate (IC50 = 41.82 μg/mL was demonstated. The results presented in this work suggested that hemicellulase has promising and attractive properties for industrial production of HT, and indicated that HT might be a valuable biological component for use in pharmaceutical products and functional foods.

Wet explosion pretreatment of sugarcane bagasse for enhanced enzymatic hydrolysis

DEFF Research Database (Denmark)

Biswas, Rajib; Uellendahl, Hinrich; Ahring, Birgitte Kiær

2014-01-01

.7% of the theoretical maximum value. Pretreatment at 200 C with oxygen exhibited enhanced enzymatic efficiency but lower xylose recovery and formation of the degradation products such as acetate, furfural and HMF of 7.6, 3.3 and 1.0 g/L, respectively. In the hydrolysis, the total sugars (glucose + xylose) yielded...

Solar photo-degradation of a pharmaceutical wastewater effluent in a semi-industrial autonomous plant.

Science.gov (United States)

Expósito, Antonio J; Durán, Antonio; Monteagudo, José M; Acevedo, Alba

2016-05-01

An industrial wastewater effluent coming from a pharmaceutical laboratory has been treated in a semi-industrial autonomous solar compound parabolic collector (CPC) plant. A photo-Fenton process assisted with ferrioxalate has been used. Up to 79% of TOC can be removed in 2 h depending on initial conditions when treating an aqueous effluent containing up to 400 ppm of initial organic carbon concentration (TOC). An initial ratio of Fe(II)/TOC higher than 0.5 guarantees a high removal. It can be seen that most of TOC removal occurs early in the first hour of reaction. After this time, mineralization was very slow, although H2O2 was still present in solution. Indeed it decomposed to form oxygen in inefficient reactions. It is clear that remaining TOC was mainly due to the presence of acetates which are difficult to degrade. Copyright © 2016 Elsevier Ltd. All rights reserved.

Parallelized system for biopolymer degradation studies through automated microresonator measurement in liquid flow

DEFF Research Database (Denmark)

Casci Ceccacci, Andrea; Morelli, Lidia; Bosco, Filippo

2015-01-01

setup unit, the system allows high-throughput measurements of resonance frequency over microresonator arrays under controlled flow conditions. We here demonstrate the acquisition of statistical data on biopolymer films degradation under enzymatic reaction over a large sample of micromechanical......In this work we present a novel automated system which allows the study of enzymatic degradation of biopolymer films coated on micromechanical resonators. The system combines an optical readout based on Blu-Ray technology with a software-controlled scanning mechanism. Integrated with a microfluidic...

Enzymatic degradation of cyclic 2,3-diphosphoglycerate to 2,3-diphosphoglycerate in Methanobacterium thermoautotrophicum

International Nuclear Information System (INIS)

Krishna Sastry, M.V.; Robertson, D.E.; Moynihan, J.A.; Roberts, M.F.

1992-01-01

2,3-Diphosphoglycerate (2,3-DPG) has been found to be the product of the enzymatic degradation of cyclic 2,3-diphosphoglycerate (cDPG) in the archaebacterium Methanobacterium thermoautotrophicum ΔH. Although 2,3-DPG has not previously been detected as a major soluble component of M. thermoautotrophicum, large pools accumulated at an incubation temperature of 50C. Under these conditions, cellular activity was significantly decreased; a return of the culture to the optimum growth temperature restored the 2,3-DPG pool back to original low levels and caused steady-state cDPG levels to increase again. While 13 CO 2 -pulse/ 12 CO 2 -chase experiments at 50C showed that the cDPG turned over, the appearance of 2,3-DPG at NMR-visible concentrations required at least 10 h. Production of 2,3-DPG in vivo was prevented by exposure of the cells to O 2 . the enzyme responsible for this hydrolysis of cDPG was purified by affinity chromatography and appears to be a 33-kDa protein. Activity was detected in the presence of oxygen and was enhanced by a solution of 1 M KCl, 25 mM MgCl 2 , and dithiothreitol. Both K m and V max have been determined at 37C; kinetics also indicate that in vitro the product, 2,3-DPG, is an inhibitor of cDPG hydrolysis. These findings are discussed in view of a proposed role for cDPG in methanogens

Structural Characterization and Enzymatic Modification of Soybean Polysaccharides

DEFF Research Database (Denmark)

Pierce, Brian; Wichmann, Jesper

% galacturonic acid, 8% xylose, 3% rhamnose, and 3% fucose. Currently, the majority of this material is disposed of as waste, increasing production costs. Opportunities exist for the develop-ment of novel functional ingredients from this abundant and underutilized ma-terial; however, efforts in this area......The work in this thesis explores the structure of soybean polysaccharides, and examines approaches for the chemical and enzymatic degradation and solu-bilization of this material. Soybean polysaccharides are produced in large quantities globally as a by-product of various soy production processes...... are currently limited by the material’s insol-ubility. A central hypothesis of this work was that by obtaining a more complete understanding of the structure of this material, chemical and enzymatic ap-proaches could be developed to modify the polysaccharides, creating soluble polysaccharide fractions...

Release of polyanions from polyelectrolyte complexes by selective degradation of the polycation

Czech Academy of Sciences Publication Activity Database

Etrych, Tomáš; Boustta, M.; Leclercq, L.; Vert, M.

2006-01-01

Roč. 21, č. 2 (2006), s. 89-105 ISSN 0883-9115 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyelectrolyte complex * enzymatic degradation * hydrolytic degradation Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.925, year: 2006

Enzymatic degradation of plant cell wall polysaccharides: the kinetic effect of competitive adsorption

DEFF Research Database (Denmark)

Bergsøe, Merete Norsker; Bloch, Line; Adler-Nissen, Jens

1999-01-01

Insoluble potato dietary fibre, isolated from potato pulp, can be enzymatically hydrolysed with the pectolytic enzyme preparation Pectinex Ultra SP from Novo Nordisk A/S, in order to produce soluble fibre. The soluble fibre has valuable functional properties for the food industry. Cloned...

In situ analysis of plant tissue underivatized carbohydrates and on-probe enzymatic degraded starch by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry by using carbon nanotubes as matrix.

Science.gov (United States)

Gholipour, Yousef; Nonami, Hiroshi; Erra-Balsells, Rosa

2008-12-15

Underivatized carbohydrates of tulip bulb and leaf tissues were characterized in situ by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) by using carbon nanotubes (CNTs) as matrix. Two sample preparation methods--(i) depositing CNTs on the fresh tissue slices placed on the probe and (ii) locating semitransparent tissues on a dried layer of CNTs on the probe--were examined. Furthermore, practicability of in situ starch analysis by MALDI-TOF MS was examined by detection of glucose originated from on-probe amyloglucosidase-catalyzed degradation of starch on the tissue surface. Besides, CNTs could efficiently desorb/ionize natural mono-, di-, and oligosaccharides extracted from tulip bulb tissues as well as glucose resulting from starch enzymatic degradation in vitro. These results were compared with those obtained by in situ MALDI-TOF MS analysis of similar tissues. Positive ion mode showed superior signal reproducibility. CNTs deposited under semitransparent tissue could also desorb/ionize neutral carbohydrates, leading to nearly complete elimination of matrix cluster signals but with an increase in tissue-originated signals. Furthermore, several experiments were carried out to compare the efficiency of 2,5-dihydroxybenzoic acid, nor-harmane, alpha-cyano-4-hydroxycinnamic acid, and CNTs as matrices for MALDI of neutral carbohydrates from the intact plant tissue surface and for enzymatic tissue starch degradation; these results are discussed in brief. Among matrices studied, the lowest laser power was needed to acquire carbohydrate signals with high signal-to-noise ratio and resolution when CNTs were used.

Temperature-induced phase transition in hydrogels of interpenetrating networks poly(N-isopropylmethacrylamide)/poly(N-isopropylacrylamide)

Czech Academy of Sciences Publication Activity Database

Šťastná, J.; Hanyková, L.; Sedláková, Zdeňka; Valentová, H.; Spěváček, Jiří

2013-01-01

Roč. 291, č. 10 (2013), s. 2409-2417 ISSN 0303-402X R&D Projects: GA ČR GA202/09/1281 Institutional support: RVO:61389013 Keywords : temperature-induced volume phase transition * poly (N-isopropylmethacrylamide) poly (Nisopropylacrylamide) interpenetrating network * 1H NMR spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.410, year: 2013

Electroless plating of PVC plastic through new surface modification method applying a semi-IPN hydrogel film

International Nuclear Information System (INIS)

Wang, Ming-Qiu; Yan, Jun; Du, Shi-Guo; Li, Hong-Guang

2013-01-01

A novel palladium-free surface activation process for electroless nickel plating was developed. This method applied a semi-Interpenetrating Polymer Network (semi-IPN) hydrogel film to modify the poly(vinyl chloride) (PVC) surface by chemical bonds. The activation process involved the formation of semi-IPN hydrogel film on the PVC surface and the immobilization of catalyst for electroless plating linking to the pretreated substrate via N-Ni chemical bond. The hydrogel layer was used as the chemisorption sites for nickel ions, and the catalyst could initiate the subsequent electroless nickel plating onto the PVC surface. Finally, a Ni–P layer was deposited on the nickel-activated PVC substrate by electroless plating technique. The composition and morphology of nickel-plated PVC foils were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results of SEM and XRD show that a compact and continuous Ni–P layer with amorphous nickel phase is formed on the PVC surface. EDS shows that the content of the nickel and the phosphorus in the deposits is 89.4 wt.% and 10.6 wt.%, respectively.

Electroless plating of PVC plastic through new surface modification method applying a semi-IPN hydrogel film

Energy Technology Data Exchange (ETDEWEB)

Wang, Ming-Qiu, E-mail: mqwang1514@163.com; Yan, Jun; Du, Shi-Guo; Li, Hong-Guang

2013-07-15

A novel palladium-free surface activation process for electroless nickel plating was developed. This method applied a semi-Interpenetrating Polymer Network (semi-IPN) hydrogel film to modify the poly(vinyl chloride) (PVC) surface by chemical bonds. The activation process involved the formation of semi-IPN hydrogel film on the PVC surface and the immobilization of catalyst for electroless plating linking to the pretreated substrate via N-Ni chemical bond. The hydrogel layer was used as the chemisorption sites for nickel ions, and the catalyst could initiate the subsequent electroless nickel plating onto the PVC surface. Finally, a Ni–P layer was deposited on the nickel-activated PVC substrate by electroless plating technique. The composition and morphology of nickel-plated PVC foils were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results of SEM and XRD show that a compact and continuous Ni–P layer with amorphous nickel phase is formed on the PVC surface. EDS shows that the content of the nickel and the phosphorus in the deposits is 89.4 wt.% and 10.6 wt.%, respectively.

Electroless plating of PVC plastic through new surface modification method applying a semi-IPN hydrogel film

Science.gov (United States)

Wang, Ming-Qiu; Yan, Jun; Du, Shi-Guo; Li, Hong-Guang

2013-07-01

A novel palladium-free surface activation process for electroless nickel plating was developed. This method applied a semi-Interpenetrating Polymer Network (semi-IPN) hydrogel film to modify the poly(vinyl chloride) (PVC) surface by chemical bonds. The activation process involved the formation of semi-IPN hydrogel film on the PVC surface and the immobilization of catalyst for electroless plating linking to the pretreated substrate via Nsbnd Ni chemical bond. The hydrogel layer was used as the chemisorption sites for nickel ions, and the catalyst could initiate the subsequent electroless nickel plating onto the PVC surface. Finally, a Ni-P layer was deposited on the nickel-activated PVC substrate by electroless plating technique. The composition and morphology of nickel-plated PVC foils were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results of SEM and XRD show that a compact and continuous Ni-P layer with amorphous nickel phase is formed on the PVC surface. EDS shows that the content of the nickel and the phosphorus in the deposits is 89.4 wt.% and 10.6 wt.%, respectively.

Estimation of Relationship Between In Situ and In Vitro Rumen Protein Degradability of Extruded Full Fat Soybean

Directory of Open Access Journals (Sweden)

Arzu Erol Tunç

2017-10-01

Full Text Available The objectives of this study were to estimate the protein degradability of extruded full fat soybean (ESB by in situ (nylon bag and in vitro enzymatic method and to develop an equation in order predict in situ degradability from in vitro values. In the study enzymatic technique; hydrolysis after 1 h (INV1 and after 24 h (INV24 by a purified protease extracted from Streptomyces griseus in a borate-phosphate buffer at pH 8 was used as in vitro method. Relationship between in situ effective protein degradability (INSE and in vitro degradability after 1 and 24 hours incubations (INV1 and INV24 were determined. In situ protein degradability was measured at 0, 2, 4, 8, 16, 24, and 48 and at 72 h incubations in the rumen of 3 Holstein cows. In the study INSE, INV1 and INV24 were determined as 58.05, 20.24 and 41.46% respectively. Despite there were differences between in situ and in vitro protein degradability values, correlation coefficients between in situ and in vitro protein degradability of ESB were high and regression equations for estimation of in situ from in vitro were found significant. As conclusion in vitro enzymatic protein degradability (INV1 and INV24 can be used for estimation of in situ effective protein degradability of extruded full fat soybean.

Enzymatic Degradation of Dynasan 114 SLN - Effect of Surfactants and Particle Size

International Nuclear Information System (INIS)

Olbrich, Carsten; Kayser, Oliver; Mueller, Rainer Helmut

2002-01-01

The degradation velocity of solid lipid nanoparticles (SLN) is - apart from drug diffusion - an important parameter determining drug release in vivo. To assess the effect of stabilizers systematically, Dynasan 114 SLN were produced with ionic surfactants (e.g. cholic acid sodium salt (NaCh), sodium dodecyl sulfate (SDS), cetylpyridiniumchloride (CPC)) and steric stabilizers (Tween 80, Poloxamer 188, 407 and Poloxamine 908) including a mixture of cholic acid sodium salt and Poloxamer 407. In addition, the size effects were investigated. The degradation velocity was measured using an in vitro lipase assay. SLN stabilized with lecithin and NaCh showed the fastest, Tween 80 the intermediate and the high molecular weight Poloxamer 407 the slowest degradation. Size effects were less pronounced for fast degrading particles (e.g. those stabilized with NaCh). No difference in the size range of 180-300-nm was observed, but a distinctly slower degradation of 800-nm SLN could be detected. For slowly degrading particles, more pronounced size effects were found. Size effects are more difficult to assess when the PCS diameters are similar, but small fractions of micrometer particles are present, besides the nanometer bulk population. The measured FFA formation is then a superposition of particles degrading at different speeds due to differences in the shape of the size distribution. Admixing of Poloxamer to NaCh had no delaying effect on the degradation of the Dynasan 114 SLN, indicating an influence of the nature of the lipid matrix that is affecting the stabilizers affinity to and anchoring onto the SLN surface

Vitamin C Degradation Products and Pathways in the Human Lens*

OpenAIRE

Nemet, Ina; Monnier, Vincent M.

2011-01-01

Vitamin C and its degradation products participate in chemical modifications of proteins in vivo through non-enzymatic glycation (Maillard reaction) and formation of different products called advanced glycation end products. Vitamin C levels are particularly high in selected tissues, such as lens, brain and adrenal gland, and its degradation products can inflict substantial protein damage via formation of advanced glycation end products. However, the pathways of in vivo vitamin C degradation ...

Effect of pretreatment severity on accumulation of major degradation products from dilute acid pretreated corn stover and subsequent inhibition of enzymatic hydrolysis of cellulose.

Science.gov (United States)

Um, Byung-Hwan; van Walsum, G Peter

2012-09-01

The concept of reaction severity, which combines residence time and temperature, is often used in the pulp and paper and biorefining industries. The influence of corn stover pretreatment severity on yield of sugar and major degradation products and subsequent effects on enzymatic cellulose hydrolysis was investigated. The pretreatment residence time and temperature, combined into the severity factor (Log R(o)), were varied with constant acid concentration. With increasing severity, increasing concentrations of furfural and 5-hydroxymethylfurfural (5-HMF) coincided with decreasing yields of oligosaccharides. With further increase in severity factor, the concentrations of furans decreased, while the formation of formic acid and lactic acid increased. For example, from severity 3.87 to 4.32, xylose decreased from 6.39 to 5.26 mg/mL, while furfural increased from 1.04 to 1.33 mg/mL; as the severity was further increased to 4.42, furfural diminished to 1.23 mg/mL as formate rose from 0.62 to 1.83 mg/mL. The effects of dilute acid hydrolyzate, acetic acid, and lignin, in particular, on enzymatic hydrolysis were investigated with a rapid microassay method. The microplate method gave considerable time and cost savings compared to the traditional assay protocol, and it is applicable to a broad range of lignocellulosic substrates.

Reactor design for minimizing product inhibition during enzymatic lignocellulose hydrolysis: I. Significance and mechanism of cellobiose and glucose inhibition on cellulolytic enzymes

DEFF Research Database (Denmark)

Andric, Pavle; Meyer, Anne S.; Jensen, Peter Arendt

2010-01-01

Achievement of efficient enzymatic degradation of cellulose to glucose is one of the main prerequisites and one of the main challenges in the biological conversion of lignocellulosic biomass to liquid fuels and other valuable products. The specific inhibitory interferences by cellobiose and glucose...... on enzyme-catalyzed cellulose hydrolysis reactions impose significant limitations on the efficiency of lignocellulose conversion especially at high-biomass dry matter conditions. To provide the base for selecting the optimal reactor conditions, this paper reviews the reaction kinetics, mechanisms......, and significance of this product inhibition, notably the cellobiose and glucose inhibition, on enzymatic cellulose hydrolysis. Particular emphasis is put on the distinct complexity of cellulose as a substrate, the multi-enzymatic nature of the cellulolytic degradation, and the particular features of cellulase...

The effects of mediator and granular activated carbon addition on degradation of trace organic contaminants by an enzymatic membrane reactor.

Science.gov (United States)

Nguyen, Luong N; Hai, Faisal I; Price, William E; Leusch, Frederic D L; Roddick, Felicity; Ngo, Hao H; Guo, Wenshan; Magram, Saleh F; Nghiem, Long D

2014-09-01

The removal of four recalcitrant trace organic contaminants (TrOCs), namely carbamazepine, diclofenac, sulfamethoxazole and atrazine by laccase in an enzymatic membrane reactor (EMR) was studied. Laccases are not effective for degrading non-phenolic compounds; nevertheless, 22-55% removal of these four TrOCs was achieved by the laccase EMR. Addition of the redox-mediator syringaldehyde (SA) to the EMR resulted in a notable dose-dependent improvement (15-45%) of TrOC removal affected by inherent TrOC properties and loading rates. However, SA addition resulted in a concomitant increase in the toxicity of the treated effluent. A further 14-25% improvement in aqueous phase removal of the TrOCs was consistently observed following a one-off dosing of 3g/L granular activated carbon (GAC). Mass balance analysis reveals that this improvement was not due solely to adsorption but also enhanced biodegradation. GAC addition also reduced membrane fouling and the SA-induced toxicity of the effluent. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enzymatic degradation of cyclic 2,3-diphosphoglycerate to 2,3-diphosphoglycerate in Methanobacterium thermoautotrophicum.

Science.gov (United States)

Sastry, M V; Robertson, D E; Moynihan, J A; Roberts, M F

1992-03-24

2,3-Diphosphoglycerate (2,3-DPG) has been found to be the product of the enzymatic degradation of cyclic 2,3-diphosphoglycerate (cDPG) in the archaebacterium Methanobacterium thermoautotrophicum delta H. Although 2,3-DPG has not previously been detected as a major soluble component of M. thermoautotrophicum, large pools accumulated at an incubation temperature of 50 degrees C (below the optimum growth temperature of 62 degrees C). Under these conditions, cellular activity was significantly decreased; a return of the culture to the optimum growth temperature restored the 2,3-DPG pool back to original low levels and caused steady-state cDPG levels to increase again. While 13CO2-pulse/12CO2-chase experiments at 50 degrees C showed that the cDPG turned over, the appearance of 2,3-DPG at NMR-visible concentrations required at least 10 h. Production of 2,3-DPG in vivo was prevented by exposure of the cells to O2. The enzyme responsible for this hydrolysis of cDPG was purified by affinity chromatography and appears to be a 33-kDa protein. Activity was detected in the presence of oxygen and was enhanced by a solution of 1 M KCl, 25 mM MgCl2, and dithiothreitol. Both Km and Vmax have been determined at 37 degrees C; kinetics also indicate that in vitro the product, 2,3-DPG, is an inhibitor of cDPG hydrolysis. These findings are discussed in view of a proposed role for cDPG in methanogens.

Non-enzymatic depolymerization of cotton cellulose by fungal mimicking metabolites

Science.gov (United States)

Anne Christine Steenkjaer Hastrup; Caitlin Howell; Bo Jensen; Frederick Green

2011-01-01

Small, low molecular weight, non-enzymatic compounds have been linked to the early stages of brown rot decay as the enzymes involved with holocellulose degradation are too large to penetrate the S3 layer of intact wood cells. We investigated the most notable of these compounds, i.e. hydrogen peroxide, iron, and oxalic acid. The former two are involved in the Fenton...

PARTIAL CHARACTERIZATION OF ENZYMATIC ACTIVITIES PRODUCED BY A WILD STRAIN OF A. NIGER

Directory of Open Access Journals (Sweden)

María Martos

2012-12-01

Full Text Available Aspergillus niger, isolated from decay citrus peels in the province of Misiones, was able to produce pectinases by submerged fermentation. The enzymatic extract exhibited polygalacturonase, pectinesterase and lyase activities. Others enzymes capable of degrading cell wall polymers were also detected in the enzymatic extract such as cellulases and xylanases. Polygalacturonase was an endo-polygalacturonase. The enzyme exhibited a maximal activity at pH range between 4.5 to 5.0, was stable in the pH range from 2.5 to 5.5 and remained unchanged when was incubated at temperatures lower than 50 ºC. The fungi produced three PG isoenzymes. The enzymatic extract was able to clarify apple juice. The results observed make the pectinolytic enzymes produced by A. niger appropriate for future application in fruit juice processing industries.

Contrasting effects of untreated textile wastewater onto the soil available nitrogen-phosphorus and enzymatic activities in aridisol.

Science.gov (United States)

Arif, Muhammad Saleem; Riaz, Muhammad; Shahzad, Sher Muhammad; Yasmeen, Tahira; Buttler, Alexandre; Garcıa-Gil, Juan Carlos; Roohi, Mahnaz; Rasool, Akhtar

2016-02-01

Water shortage and soil qualitative degradation are significant environmental problems in arid and semi-arid regions of the world. The increasing demand for water in agriculture and industry has resulted in the emergence of wastewater use as an alternative in these areas. Textile wastewater is produced in surplus amounts which poses threat to the environment as well as associated flora and fauna. A 60-day incubation study was performed to assess the effects of untreated textile wastewater at 0, 25, 50, 75, and 100% dilution levels on the physico-chemical and some microbial and enzymatic properties of an aridisol soil. The addition of textile wastewater provoked a significant change in soil pH and electrical conductivity and soil dehydrogenase and urease activities compared to the distilled-water treated control soil. Moreover, compared to the control treatment, soil phosphomonoesterase activity was significantly increased from 25 to 75% application rates, but decreased at 100% textile wastewater application rate. Total and available soil N contents increased significantly in response to application of textile wastewater. Despite significant increases in the soil total P contents after the addition of textile wastewater, soil available P content decreased with increasing concentration of wastewater. Changes in soil nutrient contents and related enzymatic activities suggested a dynamic match between substrate availability and soil N and P contents. Aridisols have high fixation and low P availability, application of textile wastewater to such soils should be considered only after careful assessment.

Three new 5-fold interpenetrating diamondoid frameworks constructed by rigid diimidazole and dicarboxylate ligands

Science.gov (United States)

Huo, Jianqiang; Yan, Shuai; Li, Haiqiang; Yu, Donghui; Arulsamy, Navamoney

2018-03-01

A series of three-dimensional coordination polymers, namely, [Cd(BIMB)(SCA)]n (1), [M(BIMB)(trans-CHDC)]n (2, M = Cd2+; 3, M = Co2+), where BIMB = 1,4-di(1H-imidazol-1-yl)benzene, SCA2- = succinate dianion, CHDC2- = cyclohexane-1,4-dicarboxylate dianion) are synthesized hydro/solvatothermal methods. The products are characterized by elemental analysis and single-crystal X-ray diffraction data. Both the dianion and BIMB bridge different pairs of the metal ions, the three complexes are polymeric and their three-dimensional topology feature a diamond-like metal-organic framework (MOF). Owing to the length of the two bridging ligands, moderate size voids are formed in the diamondoid networks. However, the voids are filled by mutual interpenetration of four independent equivalent frameworks in a 5-fold interpenetrating architecture, and there is no sufficient void volume available for any guest molecules. The phase purity and thermal stability of the compounds are verified by powder X-ray diffraction (PXRD) and thermogravimetric (TG) data. The solid-state fluorescence spectra for the 3d10 Cd2+ MOF's 1 and 2 reveal significant enhancement in their emission intensities in comparison to the non-metallated BIMB. The enhanced emission is attributed to perturbation of intra-ligand emission states due to Cd2+ coordination.

Hyaluronan degrading silica nanoparticles for skin cancer therapy

Science.gov (United States)

Scodeller, P.; Catalano, P. N.; Salguero, N.; Duran, H.; Wolosiuk, A.; Soler-Illia, G. J. A. A.

2013-09-01

We report the first nanoformulation of Hyaluronidase (Hyal) and its enhanced adjuvant effect over the free enzyme. Hyaluronic acid (HA) degrading enzyme Hyal was immobilized on 250 nm silica nanoparticles (SiNP) maintaining specific activity of the enzyme via the layer-by-layer self-assembly technique. This process was characterized by dynamic light scattering (DLS), zeta potential, infrared and UV-Vis spectroscopy, transmission electron microscopy (TEM) and enzymatic activity measurements. The nanoparticles were tested in vivo as adjuvants of carboplatin (CP), peritumorally injected in A375 human melanoma bearing mice and compared with the non-immobilized enzyme, on the basis of equal enzymatic activity. Alcian Blue staining of A375 tumors indicated large overexpression of hyaluronan. At the end of the experiment, tumor volume reduction with SiNP-immobilized Hyal was significantly enhanced compared to non-immobilized Hyal. Field emission scanning electron microscopy (FE-SEM) images together with energy dispersive X-ray spectroscopy (EDS) spectra confirmed the presence of SiNP on the tumor. We mean a proof of concept: this extracellular matrix (ECM) degrading enzyme, immobilized on SiNP, is a more effective local adjuvant of cancer drugs than the non-immobilized enzyme. This could prove useful in future therapies using other or a combination of ECM degrading enzymes.We report the first nanoformulation of Hyaluronidase (Hyal) and its enhanced adjuvant effect over the free enzyme. Hyaluronic acid (HA) degrading enzyme Hyal was immobilized on 250 nm silica nanoparticles (SiNP) maintaining specific activity of the enzyme via the layer-by-layer self-assembly technique. This process was characterized by dynamic light scattering (DLS), zeta potential, infrared and UV-Vis spectroscopy, transmission electron microscopy (TEM) and enzymatic activity measurements. The nanoparticles were tested in vivo as adjuvants of carboplatin (CP), peritumorally injected in A375 human

Theoretical Investigations of CO 2 and H 2 Sorption in an Interpenetrated Square-Pillared Metal–Organic Material

KAUST Repository

Pham, Tony; Forrest, Katherine A.; McLaughlin, Keith; Tudor, Brant; Nugent, Patrick; Hogan, Adam; Mullen, Ashley; Cioce, Christian R.; Zaworotko, Michael J.; Space, Brian

2013-01-01

Simulations of CO2 and H2 sorption and separation were performed in [Cu(dpa)2SiF6-i], a metal-organic material (MOM) consisting of an interpenetrated square grid of Cu2+ ions coordinated to 4,4′-dipyridylacetylene (dpa) rings and pillars of SiF6 2

Degradation of Endosulfan I and Endosulfan II in the Aquatic ...

African Journals Online (AJOL)

Degradation of Endosulfan I and Endosulfan II in the Aquatic Environment: A Proposed Enzymatic Kinetic Model that takes into account Adsorption/Desorption of the Pesticide by Colloidal and/or Sediment Particles.

Carbohydrate degradation mechanisms and compounds from pretreated biomass

DEFF Research Database (Denmark)

Rasmussen, Helena

The formation of inhibitors during pretreatment of lignocellulosic feedstocks is a persistent problem, and notably the compounds that retard enzymatic cellulose conversion represent an obstacle for achieving optimal enzymatic productivity and high glucose yields. Compounds with many chemical...... pretreated wheat straw after enzymatic treatment. It was found that formation of the oligophenolic degradation compounds were common across biomass sources as sugar cane bagasse and oil palm empty fruit bunches. These findings were in line with that the oligophenolic compounds arise from reactions involving...... functionalities are formed during biomass pretreatment, which gives possibilities for various chemical reactions to take place and hence formation of many new potential inhibitor compounds. This somehow overlooked contemplation formed the basis for the main hypothesis investigated in this work: Hypothesis 1...

The radiation-sterilization of semi-synthetic penicillins

International Nuclear Information System (INIS)

Jacobs, G.P.

1979-01-01

Gamma-irradiation in the dry state of the semi-synthetic penicillins, amoxycillin trihydrate, flucloxacillin-Na, methicillin-Na results in minimal degradation even following a 5 Mrad dose, suggesting the feasibility of their radiation-sterilization. Carbenicillin-Na is more susceptible to radiation-induced degradation but is nevertheless not affected by 1 Mrad dose. This 'low' dose may be suitable for carbenicillin with very low initial contamination. (author)

Enzymatic degradation of plutonium-contaminated cellulose products

International Nuclear Information System (INIS)

Heintz, C.E.; Rainwater, K.A.; Swift, L.M.; Barnes, D.L.; Worl, L.; Avens, L.

1999-01-01

Enzyme solutions produced for commercial purposes unrelated to waste management have the potential for reducing the volume of wastes in streams containing cellulose, lipid and protein materials. For example, the authors have shown that cellulases used in denim production and in detergent formulations are able to digest cellulose-containing sorbents and other cellulose-based wastes contaminated either with crude oil or with radionuclides. This presentation describes the use of one such enzyme preparation (Rapidase trademark) for the degradation of cotton sorbents intentionally contaminated with low levels of plutonium. This is part of a feasibility study to determine if such treatments have a role in reducing the volume of low level and transuranic wastes to minimize the amount of radionuclide-contaminated waste that must be disposed of in secured storage areas

Enzymatic degradation of plutonium-contaminated cellulose products

International Nuclear Information System (INIS)

Heintz, C.E.; Rainwater, K.A.; Swift, L.M.; Barnes, D.L.; Worl, L.A.

1999-01-01

Enzyme solutions produced for commercial purposes unrelated to waste management have the potential for reducing the volume of wastes in streams containing cellulose, lipid and protein materials. For example, the authors have shown previously that cellulases used in denim production and in detergent formulations are able to digest cellulose-containing sorbents and other cellulose-based wastes contaminated either with crude oil or with uranium. This presentation describes the use of one such enzyme preparation (Rapidase trademark, manufactured by Genencor, Rochester, NY) for the degradation of cotton sorbents intentionally contaminated with low levels of plutonium. This is part of a feasibility study to determine if such treatments have a role in reducing the volume of low level and transuranic wastes to minimize the amount of radionuclide-contaminated waste destined for costly disposal options

Calculation of Thomson scattering spectral fits for interpenetrating flows

Energy Technology Data Exchange (ETDEWEB)

Swadling, G. F., E-mail: george.swadling@imperial.ac.uk; Lebedev, S. V., E-mail: george.swadling@imperial.ac.uk; Burdiak, G. C.; Suttle, L.; Patankar, S.; Smith, R. A.; Bennett, M.; Suzuki-Vidal, F. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Harvey-Thompson, A. J. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1193 (United States); Rozmus, W. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2JI (Canada); Hall, G. N. [Blackett Laboratory, Imperial College, London, United Kingdom SW7 2BW and Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Yuan, J. [Key Laboratory of Pulsed Power, Institute of Fluid Physics, CAE, Mianyang 621900 (China)

2014-12-15

Collective mode optical Thomson scattering has been used to investigate the interactions of radially convergent ablation flows in Tungsten wire arrays. These experiments were carried out at the Magpie pulsed power facility at Imperial College, London. Analysis of the scattered spectra has provided direct evidence of ablation stream interpenetration on the array axis, and has also revealed a previously unobserved axial deflection of the ablation streams towards the anode as they approach the axis. It is has been suggested that this deflection is caused by the presence of a static magnetic field, advected with the ablation streams, stagnated and accrued around the axis. Analysis of the Thomson scattering spectra involved the calculation and fitting of the multi-component, non-relativistic, Maxwellian spectral density function S (k, ω). The method used to calculate the fits of the data are discussed in detail.

Anaerobic Microbial Degradation of Hydrocarbons: From Enzymatic Reactions to the Environment.

Science.gov (United States)

Rabus, Ralf; Boll, Matthias; Heider, Johann; Meckenstock, Rainer U; Buckel, Wolfgang; Einsle, Oliver; Ermler, Ulrich; Golding, Bernard T; Gunsalus, Robert P; Kroneck, Peter M H; Krüger, Martin; Lueders, Tillmann; Martins, Berta M; Musat, Florin; Richnow, Hans H; Schink, Bernhard; Seifert, Jana; Szaleniec, Maciej; Treude, Tina; Ullmann, G Matthias; Vogt, Carsten; von Bergen, Martin; Wilkes, Heinz

2016-01-01

Hydrocarbons are abundant in anoxic environments and pose biochemical challenges to their anaerobic degradation by microorganisms. Within the framework of the Priority Program 1319, investigations funded by the Deutsche Forschungsgemeinschaft on the anaerobic microbial degradation of hydrocarbons ranged from isolation and enrichment of hitherto unknown hydrocarbon-degrading anaerobic microorganisms, discovery of novel reactions, detailed studies of enzyme mechanisms and structures to process-oriented in situ studies. Selected highlights from this program are collected in this synopsis, with more detailed information provided by theme-focused reviews of the special topic issue on 'Anaerobic biodegradation of hydrocarbons' [this issue, pp. 1-244]. The interdisciplinary character of the program, involving microbiologists, biochemists, organic chemists and environmental scientists, is best exemplified by the studies on alkyl-/arylalkylsuccinate synthases. Here, research topics ranged from in-depth mechanistic studies of archetypical toluene-activating benzylsuccinate synthase, substrate-specific phylogenetic clustering of alkyl-/arylalkylsuccinate synthases (toluene plus xylenes, p-cymene, p-cresol, 2-methylnaphthalene, n-alkanes), stereochemical and co-metabolic insights into n-alkane-activating (methylalkyl)succinate synthases to the discovery of bacterial groups previously unknown to possess alkyl-/arylalkylsuccinate synthases by means of functional gene markers and in situ field studies enabled by state-of-the-art stable isotope probing and fractionation approaches. Other topics are Mo-cofactor-dependent dehydrogenases performing O2-independent hydroxylation of hydrocarbons and alkyl side chains (ethylbenzene, p-cymene, cholesterol, n-hexadecane), degradation of p-alkylated benzoates and toluenes, glycyl radical-bearing 4-hydroxyphenylacetate decarboxylase, novel types of carboxylation reactions (for acetophenone, acetone, and potentially also benzene and

An Enzymatic Treatment of Soil-Bound Prions Effectively Inhibits Replication ▿

Science.gov (United States)

Saunders, Samuel E.; Bartz, Jason C.; Vercauteren, Kurt C.; Bartelt-Hunt, Shannon L.

2011-01-01

Chronic wasting disease (CWD) and scrapie can be transmitted through indirect environmental routes, possibly via soil, and a practical decontamination strategy for prion-contaminated soil is currently unavailable. In the laboratory, an enzymatic treatment under environmentally relevant conditions (22°C, pH 7.4) can degrade soil-bound PrPSc below the limits of Western blot detection. We developed and used a quantitative serial protein misfolding cyclic amplification (PMCA) protocol to characterize the amplification efficiency of treated soil samples relative to controls of known infectious titer. Our results suggest large (104- to >106-fold) decreases in soil-bound prion infectivity following enzyme treatment, demonstrating that a mild enzymatic treatment could effectively reduce the risk of prion disease transmission via soil or other environmental surfaces. PMID:21571886

Improved antimelanogenesis and antioxidant effects of polysaccharide from Cuscuta chinensis Lam seeds after enzymatic hydrolysis.

Science.gov (United States)

Liu, Zi-Jun; Wang, Ya-Lan; Li, Qi-Ling; Yang, Liu

2018-01-01

Cuscuta chinensis polysaccharide (CPS) was extracted using hot water and enzymatically hydrolyzed C. chinensis polysaccharide (ECPS) was produced by the mannase enzymatic hydrolysis process. The purpose of this research was to investigate the antimelanogenic activity of ECPS and CPS in B16F10 melanoma cells. The in vitro antioxidant activity was assessed by their ferric iron reducing power and DPPH free radical scavenging activities. The molecular mass distribution of polysaccharides was determined using SEC-MALLS-RI. CPS was successfully enzymatically degraded using mannase and the weighted average molecular weights of CPS and ECPS were 434.6 kDa and 211.7 kDa. The results of biological activity assays suggested that the enzymatically hydrolyzed polysaccharide had superior antimelanogenic activity and antioxidant effect than the original polysaccharide. ECPS exhibited antimelanogenic activity by down-regulating the expression of tyrosinase, MITF, and TRP-1 without cytotoxic effects in B16F10 melanoma cells. In conclusion, ECPS have the potential to become a skin whitening product.

Enzymatically-Mediated Co-Production of Cellulose Nanocrystals and Fermentable Sugars

Directory of Open Access Journals (Sweden)

Dawit Beyene

2017-10-01

Full Text Available Cellulose nanocrystals (CNCs can be extracted from cellulosic materials through the degradation of non-crystalline cellulose domains in the feedstock via acid hydrolysis. However, the sugars released from the hydrolysis process cannot be easily recovered from the acid waste stream. In this study, cellulases were used to preferentially degrade non-crystalline domains with the objectives of recovering sugars and generating a feedstock with concentrated CNC precursors for a more efficient acid hydrolysis process. Filter paper and wood pulp substrates were enzyme-treated for 2–10 h to recover 20–40 wt % glucose. Substantial xylose yield (6–12 wt % was generated from wood pulp. CNC yields from acid hydrolysis of cellulases-treated filter paper, and wood pulp improved by 8–18% and 58–86%, respectively, when compared with the original substrate. It was thought that CNC precursors accumulated in the cellulases-treated feedstock due to enzymatic digestion of the more accessible non-crystalline celluloses. Therefore, acid hydrolysis from enzyme-treated feedstock will require proportionally less water and reagents resulting in increased efficiency and productivity in downstream processes. This study demonstrates that an enzymatically-mediated process allows recovery of fermentable sugars and improves acid hydrolysis efficiency for CNC production.

Cellulase-lignin interactions in the enzymatic hydrolysis of lignocellulose

Energy Technology Data Exchange (ETDEWEB)

Rahikainen, J.

2013-11-01

Today, the production of transportation fuels and chemicals is heavily dependent on fossil carbon sources, such as oil and natural gas. Their limited availability and the environmental concerns arising from their use have driven the search for renewable alternatives. Lignocellulosic plant biomass is the most abundant, but currently underutilised, renewable carbon-rich resource for fuel and chemical production. Enzymatic degradation of structural polysaccharides in lignocellulose produces soluble carbohydrates that serve as ideal precursors for the production of a vast amount of different chemical compounds. The difficulty in full exploitation of lignocellulose for fuel and chemical production lies in the complex and recalcitrant structure of the raw material. Lignocellulose is mainly composed of structural polysaccharides, cellulose and hemicellulose, but also of lignin, which is an aromatic polymer. Enzymatic degradation of cellulose and hemicellulose is restricted by several substrate- and enzyme-related factors, among which lignin is considered as one of the most problematic issues. Lignin restricts the action of hydrolytic enzymes and enzyme binding onto lignin has been identified as a major inhibitory mechanism preventing efficient hydrolysis of lignocellulosic feedstocks. In this thesis, the interactions between cellulase enzymes and lignin-rich compounds were studied in detail and the findings reported in this work have the potential to help in controlling the harmful cellulase-lignin interactions, and thus improve the biochemical processing route from lignocellulose to fuels and chemicals.

Impact of the fouling mechanism on enzymatic depolymerization of xylan in different configurations of membrane reactors

DEFF Research Database (Denmark)

Mohd Sueb, Mohd Shafiq Bin; Luo, Jianquan; Meyer, Anne S.

2017-01-01

In order to maximize enzymatic xylan depolymerization while simultaneously purifying the resulting monosaccharide (xylose), different ultrafiltration (UF) membrane reactor configurations were evaluated. Initial results showed that the two hydrolytic enzymes required for complete depolymerization...... which hindered enzymatic attack in addition to fouling. Reaction with both enzymes followed by UF was found to be the optimal configuration, providing at least 40% higher xylan hydrolysis than the cascade configuration (involving sequential reaction with each of the enzymes separately......) and the simultaneous reaction-filtration with both enzymes, respectively. This study thus confirmed that the reactor configuration has a crucial impact on the performance of both the reaction and the separation process of xylose during enzymatic xylan degradation, and that the type of fouling mechanism varies...

Processing and Dynamic Failure Characterization of Novel Impact Absorbing Transparent Interpenetrating Polymer Networks (t-IPN)

Science.gov (United States)

2014-02-01

samples were placed into the oven for the same curing treatment as before. The scanning electron microscope (SEM) photo in Figure 19 shows a typical...Interpenetrating Polymer Networks with Polyurethane and Methacrylate-based Polymers,’ S. A . Bird , PhD Dissertation, Department of Polymer and Fiber Engineering...Jajam, H. V. Tippur, S. A . Bird , and M. L. Auad, Proceedings of the 50th SES Annual Technical Meeting and ASME-AMD Summer Meeting, Providence, RI

Determining Dry Matter Degradability of Some Semi-Arid Browse ...

African Journals Online (AJOL)

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ABSTRACT: The in vitro gas production of some semi-arid browse species were evaluated. The relationship between in ... between in vitro gas measured on incubation of browse leaves and that calculated from SCFA allows the prediction of SCFA from ... with concentrate feed (40% corn, 10% wheat offal, 10% palm kernel ...

Micropollutant degradation via extracted native enzymes from activated sludge.

Science.gov (United States)

Krah, Daniel; Ghattas, Ann-Kathrin; Wick, Arne; Bröder, Kathrin; Ternes, Thomas A

2016-05-15

A procedure was developed to assess the biodegradation of micropollutants in cell-free lysates produced from activated sludge of a municipal wastewater treatment plant (WWTP). This proof-of-principle provides the basis for further investigations of micropollutant biodegradation via native enzymes in a solution of reduced complexity, facilitating downstream protein analysis. Differently produced lysates, containing a variety of native enzymes, showed significant enzymatic activities of acid phosphatase, β-galactosidase and β-glucuronidase in conventional colorimetric enzyme assays, whereas heat-deactivated controls did not. To determine the enzymatic activity towards micropollutants, 20 compounds were spiked to the cell-free lysates under aerobic conditions and were monitored via LC-ESI-MS/MS. The micropollutants were selected to span a wide range of different biodegradabilities in conventional activated sludge treatment via distinct primary degradation reactions. Of the 20 spiked micropollutants, 18 could be degraded by intact sludge under assay conditions, while six showed reproducible degradation in the lysates compared to the heat-deactivated negative controls: acetaminophen, N-acetyl-sulfamethoxazole (acetyl-SMX), atenolol, bezafibrate, erythromycin and 10,11-dihydro-10-hydroxycarbamazepine (10-OH-CBZ). The primary biotransformation of the first four compounds can be attributed to amide hydrolysis. However, the observed biotransformations in the lysates were differently influenced by experimental parameters such as sludge pre-treatment and the addition of ammonium sulfate or peptidase inhibitors, suggesting that different hydrolase enzymes were involved in the primary degradation, among them possibly peptidases. Furthermore, the transformation of 10-OH-CBZ to 9-CA-ADIN was caused by a biologically-mediated oxidation, which indicates that in addition to hydrolases further enzyme classes (probably oxidoreductases) are present in the native lysates. Although the

Microstructured poly(2-hydroxyethyl methacrylate)/poly(glycerol monomethacrylate) interpenetrating network hydrogels: UV-scattering induced accelerated formation and tensile behavior

Czech Academy of Sciences Publication Activity Database

Sadakbayeva, Zhansaya; Dušková-Smrčková, Miroslava; Šturcová, Adriana; Pfleger, Jiří; Dušek, Karel

2018-01-01

Roč. 101, April (2018), s. 304-313 ISSN 0014-3057 R&D Projects: GA ČR(CZ) GA17-08531S Institutional support: RVO:61389013 Keywords : hydrogels * interpenetrating polymer networks * kinetics Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.531, year: 2016

Efficient plant biomass degradation by thermophilic fungus Myceliophthora heterothallica

NARCIS (Netherlands)

van den Brink, J.; van Muiswinkel, G.C.; Theelen, B.; Hinz, S.W.; de Vries, R.P.

2013-01-01

Rapid and efficient enzymatic degradation of plant biomass into fermentable sugars is a major challenge for the sustainable production of biochemicals and biofuels. Enzymes that are more thermostable (up to 70 degrees C) use shorter reaction times for the complete saccharification of plant

Waste management and enzymatic treatment of Municipal Solid Waste

DEFF Research Database (Denmark)

Jensen, Jacob Wagner

generation for subsequent biogas production. Municipal solid waste (MSW) is produced in large amounts every year in the developed part of the world. The household waste composition varies between geographical areas and between seasons. However the overall content of organic and degradable material is rather......The work carried out during the Ph.D. project is part of the Danish Energy Authority funded research project called PSO REnescience and is focussed on studying the enzymatic hydrolysis and liquefaction of waste biomass. The purpose of studying the liquefaction of waste biomass is uniform slurry...... constant between 50 - 60 % wet weight and therefore holds a potential for bioenergy production. The degradable fraction has positive effects for anaerobic digestion when evaluated to desired parameters of anaerobic digestion plants. Wanted parameters are: 1) high organic content (high volatile solid...

Study of castor oil polyurethane - poly(methyl methacrylate semi-interpenetrating polymer network (SIPN reaction parameters using a 2³ factorial experimental design

Directory of Open Access Journals (Sweden)

Fernanda Oliveira Vieira da Cunha

2004-12-01

Full Text Available In this work was employed a 2³ factorial experiment design to evaluate the castor oil polyurethane-poly(methyl methacrylate semi-IPN synthesis. The reaction parameters used as independent variables were NCO/OH molar ratio, polyurethane polymerization time and methyl methacrylate (MMA content. The semi-IPNs were cured over 28 h using two thermal treatments. The polymers were characterized by infrared and Raman spectroscopy, thermal analysis and swelling profiles in n-hexane. The glass transition temperature (Tg and the swelling were more affect by the NCO/OH molar ratio variation. The semi-IPNs showed Tg from - 27 to - 6 °C and the swelling range was from 3 to 22%, according to the crosslink density. The IPN mechanical properties were dependent on the cure temperature and MMA content in it. Lower elastic modulus values were observed in IPNs cured at room temperature.

The challenges of rehabilitating denuded patches of a semi-arid environment in Kenya

NARCIS (Netherlands)

Mganga, K.Z.; Nyangito, M.M.; Musimba, N.K.R.; Nyariki, D.M.; Mwangombe, A.W.; Ekaya, W.N.; Muiri, W.M.; Clavel, D.; Francis, J.; Kaufmann, Von R.; Verhagen, J.

2010-01-01

Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the habited semiarid lands. In Kenya, grass reseeding technology has been used to combat land degradation. However,

A comparative genomic analysis of the oxidative enzymes potentially involved in lignin degradation by Agaricus bisporus

Science.gov (United States)

Harshavardhan Doddapaneni; Venkataramanan Subramanian; Bolei Fu; Dan Cullen

2013-01-01

The oxidative enzymatic machinery for degradation of organic substrates in Agaricus bisporus (Ab) is at the core of the carbon recycling mechanisms in this fungus. To date, 156 genes have been tentatively identified as part of this oxidative enzymatic machinery, which includes 26 peroxidase encoding genes, nine copper radical oxidase [including three...

Differing mechanisms of simple nitrile formation on glucosinolate degradation in Lepidium sativum and Nasturtium officinale seeds.

Science.gov (United States)

Williams, David J; Critchley, Christa; Pun, Sharon; Chaliha, Mridusmita; O'Hare, Timothy J

2009-01-01

Glucosinolates are sulphur-containing glycosides found in brassicaceous plants that can be hydrolysed enzymatically by plant myrosinase or non-enzymatically to form primarily isothiocyanates and/or simple nitriles. From a human health perspective, isothiocyanates are quite important because they are major inducers of carcinogen-detoxifying enzymes. Two of the most potent inducers are benzyl isothiocyanate (BITC) present in garden cress (Lepidium sativum), and phenylethyl isothiocyanate (PEITC) present in watercress (Nasturtium officinale). Previous studies on these salad crops have indicated that significant amounts of simple nitriles are produced at the expense of the isothiocyanates. These studies also suggested that nitrile formation may occur by different pathways: (1) under the control of specifier protein in garden cress and (2) by an unspecified, non-enzymatic path in watercress. In an effort to understand more about the mechanisms involved in simple nitrile formation in these species, we analysed their seeds for specifier protein and myrosinase activities, endogenous iron content and glucosinolate degradation products after addition of different iron species, specific chelators and various heat treatments. We confirmed that simple nitrile formation was predominantly under specifier protein control (thiocyanate-forming protein) in garden cress seeds. Limited thermal degradation of the major glucosinolate, glucotropaeolin (benzyl glucosinolate), occurred when seed material was heated to >120 degrees C. In the watercress seeds, however, we show for the first time that gluconasturtiin (phenylethyl glucosinolate) undergoes a non-enzymatic, iron-dependent degradation to a simple nitrile. On heating the seeds to 120 degrees C or greater, thermal degradation of this heat-labile glucosinolate increased simple nitrile levels many fold.

Warming and organic matter sources impact the proportion of dissolved to total activities in marine extracellular enzymatic rates

KAUST Repository

Baltar, Federico; Moran, Xose Anxelu G.; Lø nborg, Christian

2017-01-01

Extracellular enzymatic activities (EEAs) are the rate-limiting step in the degradation of organic matter. Extracellular enzymes can be found associated to cells or dissolved in the surrounding water. The proportion of cell-free EEA constitutes

Interpenetrating Polymer Networks as Innovative Drug Delivery Systems

Directory of Open Access Journals (Sweden)

Alka Lohani

2014-01-01

Full Text Available Polymers have always been valuable excipients in conventional dosage forms, also have shown excellent performance into the parenteral arena, and are now capable of offering advanced and sophisticated functions such as controlled drug release and drug targeting. Advances in polymer science have led to the development of several novel drug delivery systems. Interpenetrating polymer networks (IPNs have shown superior performances over the conventional individual polymers and, consequently, the ranges of applications have grown rapidly for such class of materials. The advanced properties of IPNs like swelling capacity, stability, biocompatibility, nontoxicity and biodegradability have attracted considerable attention in pharmaceutical field especially in delivering bioactive molecules to the target site. In the past few years various research reports on the IPN based delivery systems showed that these carriers have emerged as a novel carrier in controlled drug delivery. The present review encompasses IPNs, their types, method of synthesis, factors which affects the morphology of IPNs, extensively studied IPN based drug delivery systems, and some natural polymers widely used for IPNs.

PRELIMINARY HIGH PERFORMANCE CAPILLARY ELECTROPHORESIS (HPCE) STUDIES OF ENZYMATIC DEGRADATION OF HYALURONIC ACID BY HYALURONIDASE IN THE PRESENCE OF POLYVALENT METAL IONS.

Science.gov (United States)

Urbaniak, Bartosz; Plewa, Szymon; Kokot, Zenon Jozef

2017-01-01

The aim of this study was, at first, to examine the influence of metal ions on digestion process of hyaluronic acid by hyaluronidase (HAse) using high performance capillary electrophoresis (HPCE) method. The influence of copper(H), zinc(Il), manganese(II) ions on enzymatic degradation of HA by hyaluronidase enzyme (HA-se) were investigated. Secondly, the kinetic parameters, V(max), K(m), k(cat), and k (cat),/K(m) were determined to estimate the impact of these metal ions (Me) on digestion process of hyaluronic acid (HA). The two different HA-Me mole ratios were analyzed. The examined data were always compared to the digestion process of pure HA solution by hyaluronidase, to exhibit the differences in the digestion process of pure hyaluronan as well as the hyaluronan in the presence of metal ions. It was observed that all of the investigated metal ions have influenced the hyaluronic acid degradation process. The most important conclusion was a decrease of the kinetic parameters both K,, and V,. In the result, it can be assumed that in all of the studied samples with metal ions addition, the uncompetitive mechanism of enzyme inhibition occurred. The results of this study may give new insight into foregoing knowledge about hyaluronic acid behavior. Due to the fact that our study was carried out only for three different metal ions in two concentrations, it is necessary to continue further research comprising wider range of metal ions and their concentrations.

Combined subcritical water and enzymatic hydrolysis for reducing sugar production from coconut husk

Science.gov (United States)

Muharja, Maktum; Junianti, Fitri; Nurtono, Tantular; Widjaja, Arief

2017-05-01

Coconut husk wastes are abundantly available in Indonesia. It has a potential to be used into alternative renewable energy sources such as hydrogen using enzymatic hydrolysis followed by a fermentation process. Unfortunately, enzymatic hydrolysis is hampered by the complex structure of lignocellulose, so the cellulose component is hard to degrade. In this study, Combined Subcritical Water (SCW) and enzymatic hydrolysis are applied to enhance fermentable, thereby reducing production of sugar from coconut husk. There were two steps in this study, the first step was coconut husk pretreated by SCW in batch reactor at 80 bar and 150-200°C for 60 minutes reaction time. Secondly, solid fraction from the results of SCW was hydrolyzed using the mixture of pure cellulose and xylanase enzymes. Analysis was conducted on untreated and SCW-treated by gravimetric assay, liquid fraction after SCW and solid fraction after enzymatic hydrolysis using DNS assay. The maximum yield of reducing sugar (including xylose, arabinose glucose, galactose, mannose) was 1.254 gr per 6 gr raw material, representing 53.95% of total sugar in coconut husk biomass which was obtained at 150°C 80 bar for 60 minutes reaction time of SCW-treated and 6 hour of enzymatic hydrolysis using mixture of pure cellulose and xylanase enzymes (18.6 U /gram of coconut husk).

Effects of the bradykinin antagonist B4310 on smooth muscles and blood pressure in the rat, and its enzymatic degradation.

Science.gov (United States)

Griesbacher, T.; Lembeck, F.; Saria, A.

1989-01-01

1. Six competitive bradykinin (Bk) antagonists were tested for their agonistic properties on the rat uterus. Five of these peptides showed agonistic effects only at concentrations at least two orders of magnitude higher than those of bradykinin. 2. The antagonistic potency of Lys-Lys-3-Hyp-5,8-Thi-7-DPhe-Bk (B4310) in the rat uterus (pA2 = 7.24) and in the rat duodenum (pA2 = 7.31) was very similar to that determined in an earlier study for the antagonism of the bradykinin-induced stimulation of the trigeminal nerve in the rabbit iris sphincter muscle preparation (pA2 = 7.59). 3. The fall in mean arterial blood pressure induced by i.a. injections of bradykinin was greatly reduced during an i.a. infusion of B4310, but not 10 min thereafter, which indicates a rapid inactivation of B4310 in vivo. Bacitracin possibly interferes with the enzymatic cleavage of B4310 but seems to have no effect on the degradation of bradykinin. 4. An i.a. infusion of captopril greatly enhanced the potency of bradykinin in inducing a fall in arterial blood pressure, confirming the important role of angiotensin converting enzyme in the cleavage of bradykinin. However, the design of this experiment did not allow conclusions about the effect of captopril on the degradation of B4310. 5. B4310 incubated with rat lung tissue disappeared from the incubation medium within a few minutes, i.e. as fast as bradykinin, which explains its short duration of action in vivo. Captopril partially inhibited the cleavage of both bradykinin and B4310.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2655805

Comparison of Enzymatic and Ultrasonic Extraction of Albumin from Defatted Pumpkin (Cucurbita pepo Seed Powder

Directory of Open Access Journals (Sweden)

Gia Loi Tu

2015-01-01

Full Text Available In this study, ultrasound- and enzyme-assisted extractions of albumin (water-soluble protein group from defatted pumpkin (Cucurbita pepo seed powder were compared. Both advanced extraction techniques strongly increased the albumin yield in comparison with conventional extraction. The extraction rate was two times faster in the ultrasonic extraction than in the enzymatic extraction. However, the maximum albumin yield was 16 % higher when using enzymatic extraction. Functional properties of the pumpkin seed albumin concentrates obtained using the enzymatic, ultrasonic and conventional methods were then evaluated. Use of hydrolase for degradation of cell wall of the plant material did not change the functional properties of the albumin concentrate in comparison with the conventional extraction. The ultrasonic extraction enhanced water-holding, oil-holding and emulsifying capacities of the pumpkin seed albumin concentrate, but slightly reduced the foaming capacity, and emulsion and foam stability.

Processing surface sizing starch using oxidation, enzymatic hydrolysis and ultrasonic treatment methods--Preparation and application.

Science.gov (United States)

Brenner, Tobias; Kiessler, Birgit; Radosta, Sylvia; Arndt, Tiemo

2016-03-15

The surface application of starch is a well-established method for increasing paper strength. In surface sizing, a solution of degraded starch is applied to the paper. Two procedures have proved valuable for starch degradation in the paper mill: enzymatic and thermo-oxidative degradation. The objective of this study was to determine achievable efficiencies of cavitation in preparing degraded starch for surface application on paper. It was found that ultrasonic-assisted starch degradation can provide a starch solution that is suitable for surface sizing. The molecular composition of starch solutions prepared by ultrasonic treatment differed from that of starch solutions degraded by enzymes or by thermo-oxidation. Compared to commercial degradation processes, this resulted in intensified film formation and in greater penetration during surface sizing and ultimately in a higher starch content of the paper. Paper sized with ultrasonically treated starch solutions show the same strength properties compared to commercially sized paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation and protection of DNAzymes on human skin.

Science.gov (United States)

Marquardt, Kay; Eicher, Anna-Carola; Dobler, Dorota; Höfer, Frank; Schmidts, Thomas; Schäfer, Jens; Renz, Harald; Runkel, Frank

2016-10-01

DNAzymes are catalytic nucleic acid based molecules that have become a new class of active pharmaceutical ingredients (API). Until now, five DNAzymes have entered clinical trials. Two of them were tested for topical application, whereby dermally applied DNAzymes had been prone to enzymatic degradation. To protect the DNAzymes the enzymatic activity of human skin has to be examined. Therefore, the enzymatic activity of human skin was qualitatively and quantitatively analyzed. Activity similar to that of DNase II could be identified and the specific activity was determined to be 0.59Units/mg. These results were used to develop an in vitro degradation assay to screen different kinds of protective systems on human skin. The chosen protective systems consisted of biodegradable chitosans or polyethylenimine, which forms polyplexes when combined with DNAzymes. The polyplexes were characterized in terms of particle size, zeta potential, stability and degree of complexation. The screening revealed that the protective efficiency of the polyplexes depended on the polycation and the charge ratio (ξ). At a critical ξ ratio between 1.0 and 4.1 and at a maximal zeta potential, sufficient protection of the DNAzyme was achieved. The results of this study will be helpful for the development of a protective dermal drug delivery systems using polyplexes. Copyright © 2016 Elsevier B.V. All rights reserved.

Interpenetrating Polymer Network (IPN with Epoxidized and Acrylated Bioresins and their Composites with Glass and Jute Fibres

Directory of Open Access Journals (Sweden)

Francisco Cardona

2016-02-01

Full Text Available Epoxidized (EHO and acrylated (AEHO bio-resins from hemp oil were synthesized, and their interpenetrating networks (IPNs were investigated in reinforced bio-composites with natural jute fibres and glass fibres. The mechanical properties (tensile, flexural, Charpy impact, and inter-laminar shear and viscoelastic properties (glass transition temperature, storage modulus, and crosslink density of the bio-resins and their hybrid IPNs EHO/AEHO system were investigated as a function of the level of bio-resin hybridization. The hybrid bio-resins exhibited interpenetrating network (IPN behaviour. Composites prepared with the synthetic vinyl ester (VE and epoxy resins showed superior mechanical and viscoelastic properties compared with their bio-resins and IPNs-based counterparts. With glass fibre (GF reinforcement, increases in the EHO content of the IPNs resulted in increased stiffness of the composites, while the strength, inter-laminar shear strength (ILSS, and impact resistance decreased. However, in the jute fibre reinforced bio-composites, increases in AEHO content generated increased tensile modulus, ILSS, and mechanical strength of the bio-materials. Crosslink density and glass transition temperature (Tg were also higher for the synthetic resins than for the bio-resins. Increased AEHO content of the IPNs resulted in improved viscoelastic properties.

Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s bearing functionalizable carbonate building blocks: II. Enzymatic biodegradation and in vitro biocompatibility assay.

Science.gov (United States)

Yang, Jing; Tian, Weisheng; Li, Qiaobo; Li, Yang; Cao, Amin

2004-01-01

In a previous study, we have reported chemical synthesis of novel aliphatic poly(butylene succinate-co-cyclic carbonate) P(BS-co-CC)s bearing various functionalizable carbonate building blocks, and this work will continue to present our new studies on their enzymatic degradation and in vitro cell biocompatibility assay. First, enzymatic degradation of the novel P(BS-co-CC) film samples was investigated with two enzymes of lipase B Candida Antartic (Novozyme 435) and lipase Porcine Pancreas PPL, and it was revealed that copolymerizing linear poly(butylene succinate) PBS with a functionalizable carbonate building block could remarkably accelerate the enzymatic degradation of a synthesized product P(BS-co-CC), and its biodegradation behavior was found to strongly depend on the overall impacts of several important factors as the cyclic carbonate (CC) comonomer structure and molar content, molar mass, thermal characteristics, morphology, the enzyme-substrate specificity, and so forth. Further, the biodegraded residual film samples and water-soluble enzymatic degradation products were allowed to be analyzed by means of proton nuclear magnetic resonance (1H NMR), gel permeation chromatograph (GPC), differential scanning calorimeter (DSC), attenuated total reflection FTIR (ATR-FTIR), scanning electron microscope (SEM), and liquid chromatograph-mass spectrometry (LC-MS). On the experimental evidences, an exo-type mechanism of enzymatic chain hydrolysis preferentially occurring in the noncrystalline domains was suggested for the synthesized new P(BS-co-CC) film samples. With regard to their cell biocompatibilities, an assay with NIH 3T3 mouse fibroblast cell was conducted using the novel synthesized P(BS-co-CC) films as substrates with respect to the cell adhesion and proliferation, and these new biodegradable P(BS-co-CC) samples were found to exhibit as low cell toxicity as the PLLA control, particularly the two samples of poly(butylene succinate-co-18.7 mol % dimethyl

Evident elevation of atmospheric monoterpenes due to degradation-induced species changes in a semi-arid grassland.

Science.gov (United States)

Wang, Hongjun; Wang, Xinming; Zhang, Yanli; Mu, Yujing; Han, Xingguo

2016-01-15

Biogenic volatile organic compounds (BVOCs) emitted from plants have substantial effects on atmospheric chemistry/physics and feedbacks on ecosystem function. The on-going climate change and anthropogenic disturbance have been confirmed to cause the evident degradation of grassland with shift of plant community, and hence BVOCs emissions were suspected to be altered due to the different BOVCs emission potentials of different species. In this study, we investigated BVOCs concentration above ground surface during growing season in a degraded semi-arid grassland (41°2' N-45°6' N, 113°5'-117°8') in Inner Mongolia. The observed monoterpenes' concentrations varied from 0.10 to 215.78 μg m(-3) (34.88 ± 9.73 μg m(-3) in average) across 41 sites. Compared to non-degraded grassland, concentrations of monoterpenes were about 180 times higher at the sites dominated by subshrub--Artemisia frigida, a preponderant species under drought stress and over-grazing. The biomass of A. frigida explained 51.39% of the variation of monoterpenes' concentrations. α-pinene, β-pinene and γ-terpinene dominated in the 10 determined monoterpenes, accounting for 37.72 ± 2.98%, 14.65 ± 2.55% and 10.50 ± 2.37% of the total monoterpenes concentration, respectively. Low isoprene concentrations (≤ 3.25 μg m(-3)) were found and sedge biomass contributed about 51.76% to their spatial variation. α-pinene and isoprene emissions at noon were as high as 515.53 ± 88.34 μg m(-2)h(-1) and 7606.19 ± 1073.94 μg m(-2) h(-1) in A. frigida- and sedge-dominated areas where their biomass were 236.90 g m(-2) and 72.37 g m(-2), respectively. Our results suggested that the expansion of A. frigida and sedge caused by over-grazing and climatic stresses may increase local ambient BVOCs concentration in grassland. Copyright © 2015 Elsevier B.V. All rights reserved.

Establishment of an Arabidopsis callus system to study the interrelations of biosynthesis, degradation and accumulation of carotenoids

Science.gov (United States)

Schaub, Patrick; Rodriguez-Franco, Marta; Cazzonelli, Christopher Ian; Álvarez, Daniel; Wüst, Florian

2018-01-01

The net amounts of carotenoids accumulating in plant tissues are determined by the rates of biosynthesis and degradation. While biosynthesis is rate-limited by the activity of PHYTOENE SYNTHASE (PSY), carotenoid losses are caused by catabolic enzymatic and non-enzymatic degradation. We established a system based on non-green Arabidopsis callus which allowed investigating major determinants for high steady-state levels of β-carotene. Wild-type callus development was characterized by strong carotenoid degradation which was only marginally caused by the activity of carotenoid cleavage oxygenases. In contrast, carotenoid degradation occurred mostly non-enzymatically and selectively affected carotenoids in a molecule-dependent manner. Using carotenogenic pathway mutants, we found that linear carotenes such as phytoene, phytofluene and pro-lycopene resisted degradation and accumulated while β-carotene was highly susceptible towards degradation. Moderately increased pathway activity through PSY overexpression was compensated by degradation revealing no net increase in β-carotene. However, higher pathway activities outcompeted carotenoid degradation and efficiently increased steady-state β-carotene amounts to up to 500 μg g-1 dry mass. Furthermore, we identified oxidative β-carotene degradation products which correlated with pathway activities, yielding β-apocarotenals of different chain length and various apocarotene-dialdehydes. The latter included methylglyoxal and glyoxal as putative oxidative end products suggesting a potential recovery of carotenoid-derived carbon for primary metabolic pathways. Moreover, we investigated the site of β-carotene sequestration by co-localization experiments which revealed that β-carotene accumulated as intra-plastid crystals which was confirmed by electron microscopy with carotenoid-accumulating roots. The results are discussed in the context of using the non-green calli carotenoid assay system for approaches targeting high

Degradation of Polyester Polyurethane by Bacterial Polyester Hydrolases

Directory of Open Access Journals (Sweden)

Juliane Schmidt

2017-02-01

Full Text Available Polyurethanes (PU are widely used synthetic polymers. The growing amount of PU used industrially has resulted in a worldwide increase of plastic wastes. The related environmental pollution as well as the limited availability of the raw materials based on petrochemicals requires novel solutions for their efficient degradation and recycling. The degradation of the polyester PU Impranil DLN by the polyester hydrolases LC cutinase (LCC, TfCut2, Tcur1278 and Tcur0390 was analyzed using a turbidimetric assay. The highest hydrolysis rates were obtained with TfCut2 and Tcur0390. TfCut2 also showed a significantly higher substrate affinity for Impranil DLN than the other three enzymes, indicated by a higher adsorption constant K. Significant weight losses of the solid thermoplastic polyester PU (TPU Elastollan B85A-10 and C85A-10 were detected as a result of the enzymatic degradation by all four polyester hydrolases. Within a reaction time of 200 h at 70 °C, LCC caused weight losses of up to 4.9% and 4.1% of Elastollan B85A-10 and C85A-10, respectively. Gel permeation chromatography confirmed a preferential degradation of the larger polymer chains. Scanning electron microscopy revealed cracks at the surface of the TPU cubes as a result of enzymatic surface erosion. Analysis by Fourier transform infrared spectroscopy indicated that the observed weight losses were a result of the cleavage of ester bonds of the polyester TPU.

Photoelectrochemical enzymatic biosensors.

Science.gov (United States)

Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

2017-06-15

Enzymatic biosensors have been valuable bioanalytical devices for analysis of diverse targets in disease diagnosis, biological and biomedical research, etc. Photoelectrochemical (PEC) bioanalysis is a recently emerged method that promptly becoming a subject of new research interests due to its attractive potential for future bioanalysis with high sensitivity and specificity. PEC enzymatic biosensors integrate the inherent sensitivities of PEC bioanalysis and the selectivity of enzymes and thus share their both advantages. Currently, PEC enzymatic biosensors have become a hot topic of significant research and the recent impetus has grown rapidly as demonstrated by increased research papers. Given the pace of advances in this area, this review will make a thorough discussion and survey on the fundamentals, sensing strategies, applications and the state of the art in PEC enzymatic biosensors, followed by future prospects based on our own opinions. We hope this work could provide an accessible introduction to PEC enzymatic biosensors for any scientist. Copyright © 2016 Elsevier B.V. All rights reserved.

Dielectric elastomers, with very high dielectric permittivity, based on silicone and ionic interpenetrating networks

DEFF Research Database (Denmark)

Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren

2015-01-01

permittivity and the Young's modulus of the elastomer. One system that potentially achieves this involves interpenetrating polymer networks (IPNs), based on commercial silicone elastomers and ionic networks from amino- and carboxylic acid-functional silicones. The applicability of these materials as DEs...... are obtained while dielectric breakdown strength and Young's modulus are not compromised. These good overall properties stem from the softening effect and very high permittivity of ionic networks – as high as ε′ = 7500 at 0.1 Hz – while the silicone elastomer part of the IPN provides mechanical integrity...

Degradation of Synthetic Dyes by Laccases – A Mini-Review

Directory of Open Access Journals (Sweden)

Legerská Barbora

2016-06-01

Full Text Available Laccases provide a promising future as a tool to be used in the field of biodegradation of synthetic dyes with different chemical structures. These enzymes are able to oxidize a wide range of phenolic substrates without the presence of additional co-factors. Laccases have been confirmed for their potential of synthetic dye degradation from wastewater and degradation products of these enzymatic reactions become less toxic than selected dyes. This study discusses the potential of laccase enzymes as agents for laccase-catalyzed degradation in terms of biodegradation efficiency of synthetic dyes, specifically: azo dyes, triphenylmethane, indigo and anthraquinone dyes. Review also summarizes the laccase-catalyzed degradation mechanisms of the selected synthetic dyes, as well as the degradation products and the toxicity of the dyes and their degradation products.

Temperature induced decoupling of enzymatic hydrolysis and carbon remineralization in long-term incubations of Arctic and temperate sediments

DEFF Research Database (Denmark)

Robador, Alberto; Brüchert, Volker; Steen, Andrew

2010-01-01

explored the temperature sensitivity of enzymatic hydrolysis and its connection to subsequent steps in anoxic organic carbon degradation in long-term incubations of sediments from the Arctic and the North Sea. These sediments were incubated under anaerobic conditions for 24 months at temperatures of 0, 10......, and 20 ºC. The short-term temperature response of the active microbial community was tested in temperature gradient block incubations. The temperature optimum of extracellular enzymatic hydrolysis, as measured with a polysaccharide (chondroitin sulfate), differed between Arctic and temperate habitats...

A constitutive law for degrading bioresorbable polymers.

Science.gov (United States)

Samami, Hassan; Pan, Jingzhe

2016-06-01

This paper presents a constitutive law that predicts the changes in elastic moduli, Poisson's ratio and ultimate tensile strength of bioresorbable polymers due to biodegradation. During biodegradation, long polymer chains are cleaved by hydrolysis reaction. For semi-crystalline polymers, the chain scissions also lead to crystallisation. Treating each scission as a cavity and each new crystal as a solid inclusion, a degrading semi-crystalline polymer can be modelled as a continuum solid containing randomly distributed cavities and crystal inclusions. The effective elastic properties of a degrading polymer are calculated using existing theories for such solid and the tensile strength of the degrading polymer is predicted using scaling relations that were developed for porous materials. The theoretical model for elastic properties and the scaling law for strength form a complete constitutive relation for the degrading polymers. It is shown that the constitutive law can capture the trend of the experimental data in the literature for a range of biodegradable polymers fairly well. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bioethanol production: Pretreatment and enzymatic hydrolysis of softwood

Energy Technology Data Exchange (ETDEWEB)

Tengborg, Charlotte

2000-05-01

The enzymatic hydrolysis process can be used to produce bioethanol from softwood, which are the dominating raw material in the Northern hemisphere. This thesis deals with the development of the process focusing on the pretreatment and the enzymatic hydrolysis stages. The influence of pretreatment conditions on sugar yield, and the effect of inhibitors on the ethanol yield, were investigated for spruce and pine. The maximum yields of hemicellulose sugars and glucose were obtained under different pretreatment conditions. This indicates that two-stage pretreatment may be preferable. The added catalysts, H{sub 2}SO{sub 4} and SO{sub 2}, resulted in similar total sugar yields about 40 g/100 g dry raw material. However, the fermentability of SO{sub 2}-impregnated material was better. This pretreatment resulted in the formation of inhibitors to the subsequent process steps, e.g. sugar and lignin degradation products. The glucose yield in the enzymatic hydrolysis stage was affected by various parameters such as enzyme loading, temperature, pH, residence time, substrate concentration, and agitation. To decrease the amount of fresh water used and thereby waste water produced, the sugar-rich prehydrolysate from the pretreatment step was included in the enzymatic hydrolysis of the solid fraction, resulting in a reduction in the cellulose conversion of up to 36%. Different prehydrolysate detoxification methods, such as treatment with Ca(OH){sub 2}, laccase, and fermentation using yeast, were investigated. The latter was shown to be very efficient. The amount of fresh water used can be further reduced by recycling various process streams. This was simulated experimentally in a bench-scale process. A reduction in fresh water demand of 50% was obtained without any further negative effects on either hydrolysis or fermentation.

Enzymatic added extraction and clarification of fruit juices-A review.

Science.gov (United States)

Sharma, Harsh P; Patel, Hiral; Sugandha

2017-04-13

Enzymatic treatment for juice extraction is most commonly used now a days. The enzymatic process is claimed to offer a number of advantages over mechanical-thermal comminution of several fruit pulps. Enzymes are an integral component of modern fruit juice manufacturing and are highly suitable for optimizing processes. Their main purposes are: increase extraction of juice from raw material, increase processing efficiency (pressing, solid settling or removal), and generate a final product that is clear and visually attractive. Juice extraction can be done by using various mechanical processes, which may be achieved through diffusion extraction, decanter centrifuge, screw type juice extractor, fruit pulper and by different types of presses. Enzymatic treatment prior to mechanical extraction significantly improves juice recovery compared to any other extraction process. Enzymatic hydrolysis of the cell walls increases the extraction yield, reducing sugars, soluble dry matter content and galacturonic acid content and titrable acidity of the products. Enzymatic degradation of the biomaterial depends upon the type of enzyme, incubation time, incubation temperature, enzyme concentration, agitation, pH and use of different enzyme combinations. We can conclude from the technical literature that use of the enzymes i.e. cellulases, pectinases, amylases and combination of these enzymes can give better juice yield with superior quality of the fruit juice. Pectinase enzyme can give maximum juice yield i.e. 92.4% at 360 minutes incubation time, 37°C incubation temperature and 5 mg/100 g of enzyme concentration. Whereas the combination of two enzymes i.e. pectin methyl esterase (PME) and polygalacturonase (PG) at 120 minutes of incubation time, 50°C of incubation temperature and 0.05 mg/100 gm of enzymatic concentration can give the maximum yield of 96.8% for plum fruits. This paper discusses the use of enzymes in fruit juice production focusing on the juice recovery

Influence of pre-treatment on enzymatic degumming of apocynum venetum bast fibers in supercritical carbon dioxide

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Gao Shi-Hui

2015-01-01

Full Text Available Pre-treatment of apocynum venetum bast fibers in supercritical carbon dioxide can improve the efficiency of enzymatic degumming of apocynum venetum bast fiber. This paper studies experimentally effect of pressure and degumming time on degradation rate, the results can be used for optimal design of degumming.

Impact of Heavy Metals in Enzymatic Activity of Soils from Hidalgo, Mexico

International Nuclear Information System (INIS)

Reyes-Ortigoza, A. L.; Reyes-Solis, I. E.; Galicia-Palacios, M. S.; Montiel-Arteaga, S.

2009-01-01

The soils from Valle of Mezquital, Hidalgo, Mexico have been irrigated with waste waters from Mexico City for more than 88 years. the present investigation was made in order to know the relationship between heavy metal contents and time of irrigation with waste waters and production of CO 2 and enzymatic activity in soils from Valle Mezquital for knowing the disponibility of nutrients and degradation of soils. (Author)

Determination of carbon isotope ratios in plant starch via selective enzymatic hydrolysis

International Nuclear Information System (INIS)

Schimmelmann, A.; DeNiro, M.J.

1983-01-01

A method for the determination of the carbon isotope ratios in bipolymers hydrolyzed by enzymatic action consists of separating the monomer by passage through a dialysis membrane and then combusting the monomer prior to isotopic analysis. The method is described for application to the analysis of starch, but it should find application for polymers than can be degraded quantitatively to monomers and/or oligomers using specific hydrolytic enzymes

Characterization of Thermal Stability of Synthetic and Semi-Synthetic Engine Oils

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Anand Kumar Tripathi

2015-03-01

Full Text Available Engine oils undergo oxidative degradation and wears out during service. Hence it is important to characterize ageing of engine oils at different simulated conditions to evaluate the performance of existing oils and also design new formulations. This work focuses on characterizing the thermo-oxidative degradation of synthetic and semi-synthetic engine oils aged at 120, 149 and 200 °C. Apparent activation energy of decomposition of aged oils evaluated using the isoconversional Kissinger-Akahira-Sunose technique was used as a thermal stability marker. The temporal variation of stability at different ageing temperatures was corroborated with kinematic viscosity, oxidation, sulfation and nitration indices, total base number, antiwear additive content and molecular structure of the organic species present in the oils. At the lowest temperature employed, synthetic oil underwent higher rate of oxidation, while semi-synthetic oil was stable for longer time periods. At higher temperatures, the initial rate of change of average apparent activation energy of synthetic oil correlated well with a similar variation in oxidation number. A mixture of long chain linear, branched, and cyclic hydrocarbons were observed when semi-synthetic oil was degraded at higher temperatures.

Comparison of Enzymatic and Ultrasonic Extraction of Albumin from Defatted Pumpkin (Cucurbita pepo)
Seed Powder.

Science.gov (United States)

Tu, Gia Loi; Bui, Thi Hoang Nga; Tran, Thi Thu Tra; Ton, Nu Minh Nguyet; Man Le, Van Viet

2015-12-01

In this study, ultrasound- and enzyme-assisted extractions of albumin (water-soluble protein group) from defatted pumpkin ( Cucurbita pepo ) seed powder were compared. Both advanced extraction techniques strongly increased the albumin yield in comparison with conventional extraction. The extraction rate was two times faster in the ultrasonic extraction than in the enzymatic extraction. However, the maximum albumin yield was 16% higher when using enzymatic extraction. Functional properties of the pumpkin seed albumin concentrates obtained using the enzymatic, ultrasonic and conventional methods were then evaluated. Use of hydrolase for degradation of cell wall of the plant material did not change the functional properties of the albumin concentrate in comparison with the conventional extraction. The ultrasonic extraction enhanced water-holding, oil-holding and emulsifying capacities of the pumpkin seed albumin concentrate, but slightly reduced the foaming capacity, and emulsion and foam stability.

Enzymatic Mechanism for Arabinan Degradation and Transport in the Thermophilic Bacterium Caldanaerobius polysaccharolyticus.

Science.gov (United States)

Wefers, Daniel; Dong, Jia; Abdel-Hamid, Ahmed M; Paul, Hans Müller; Pereira, Gabriel V; Han, Yejun; Dodd, Dylan; Baskaran, Ramiya; Mayer, Beth; Mackie, Roderick I; Cann, Isaac

2017-09-15

The plant cell wall polysaccharide arabinan provides an important supply of arabinose, and unraveling arabinan-degrading strategies by microbes is important for understanding its use as a source of energy. Here, we explored the arabinan-degrading enzymes in the thermophilic bacterium Caldanaerobius polysaccharolyticus and identified a gene cluster encoding two glycoside hydrolase (GH) family 51 α-l-arabinofuranosidases (CpAbf51A, CpAbf51B), a GH43 endoarabinanase (CpAbn43A), a GH27 β-l-arabinopyranosidase (CpAbp27A), and two GH127 β-l-arabinofuranosidases (CpAbf127A, CpAbf127B). The genes were expressed as recombinant proteins, and the functions of the purified proteins were determined with para -nitrophenyl ( p NP)-linked sugars and naturally occurring pectin structural elements as the substrates. The results demonstrated that CpAbn43A is an endoarabinanase while CpAbf51A and CpAbf51B are α-l-arabinofuranosidases that exhibit diverse substrate specificities, cleaving α-1,2, α-1,3, and α-1,5 linkages of purified arabinan-oligosaccharides. Furthermore, both CpAbf127A and CpAbf127B cleaved β-arabinofuranose residues in complex arabinan side chains, thus providing evidence of the function of this family of enzymes on such polysaccharides. The optimal temperatures of the enzymes ranged between 60°C and 75°C, and CpAbf43A and CpAbf51A worked synergistically to release arabinose from branched and debranched arabinan. Furthermore, the hydrolytic activity on branched arabinan oligosaccharides and degradation of pectic substrates by the endoarabinanase and l-arabinofuranosidases suggested a microbe equipped with diverse activities to degrade complex arabinan in the environment. Based on our functional analyses of the genes in the arabinan degradation cluster and the substrate-binding studies on a component of the cognate transporter system, we propose a model for arabinan degradation and transport by C. polysaccharolyticus IMPORTANCE Genomic DNA sequencing and

Localized Enzymatic Degradation of Polymers: Physics and Scaling Laws

Science.gov (United States)

Lalitha Sridhar, Shankar; Vernerey, Franck

2018-03-01

Biodegradable polymers are naturally abundant in living matter and have led to great advances in controlling environmental pollution due to synthetic polymer products, harnessing renewable energy from biofuels, and in the field of biomedicine. One of the most prevalent mechanisms of biodegradation involves enzyme-catalyzed depolymerization by biological agents. Despite numerous studies dedicated to understanding polymer biodegradation in different environments, a simple model that predicts the macroscopic behavior (mass and structural loss) in terms of microphysical processes (enzyme transport and reaction) is lacking. An interesting phenomenon occurs when an enzyme source (released by a biological agent) attacks a tight polymer mesh that restricts free diffusion. A fuzzy interface separating the intact and fully degraded polymer propagates away from the source and into the polymer as the enzymes diffuse and react in time. Understanding the characteristics of this interface will provide crucial insight into the biodegradation process and potential ways to precisely control it. In this work, we present a centrosymmetric model of biodegradation by characterizing the moving fuzzy interface in terms of its speed and width. The model predicts that the characteristics of this interface are governed by two time scales, namely the polymer degradation and enzyme transport times, which in turn depend on four main polymer and enzyme properties. A key finding of this work is simple scaling laws that can be used to guide biodegradation of polymers in different applications.

Microcantilever sensors for fast analysis of enzymatic degradation of poly (D, L-lactide)

DEFF Research Database (Denmark)

Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja

2015-01-01

of the biodegradation rate of PDLLA with a minute amount of sample and without the need of thermal and chemical acceleration. The degradation rate of the polymer has been estimated by multilayer cantilever theory and model simulation. A bulk degradation rate of 0.24 μg mm-2 hour-1 is estimated which agrees well...

Enzymatic Degradation of Poly(ethylene 2,5-furanoate Powders and Amorphous Films

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Simone Weinberger

2017-10-01

Full Text Available Poly(ethylene 2,5-furanoate (PEF is arousing great interest as a biobased alternative to plastics like poly(ethylene terephthalate (PET due to its wide range of potential applications, such as food and beverage packaging, clothing, and in the car industry. In the present study, the hydrolysis of PEF powders of different molecular masses (Mn = 55, Mw = 104 kg/mol and Mn = 18, Mw = 29 kg/mol and various particle sizes (180 < d and 180 < d < 425 µm using cutinase 1 from Thermobifida cellulosilytica (Thc_cut1 was studied. Thereby, the effects of molecular mass, particle size and crystallinity on enzymatic hydrolysis were investigated. The results show that particles with lower molecular mass are hydrolyzed faster than those with higher masses, and that the higher the molecular mass, the lower the influence of the particle size on the hydrolysis. Furthermore, cutinases from Humicola insolens (HiC and Thc_cut1 were compared with regard to their hydrolytic activity on amorphous PEF films (measured as release of 2,5-furandicarboxylic acid (FDCA and weight loss in different reaction media (1 M KPO pH 8, 0.1 M Tris-HCl pH 7 and at different temperatures (50 °C and 65 °C. A 100% hydrolysis of the PEF films was achieved after only 72 h of incubation with a HiC in 1 M KPO pH 8 at 65 °C. Moreover, the hydrolysis reaction was monitored by LC/TOF-MS analysis of the released reaction products and by Scanning Electron Microscopy (SEM examination of the polymer surfaces. Enzymatic hydrolysis of PEF with Thc_cut1 and HiC has potential for use in surface functionalization and recycling purposes.

Enzymatic oxalic acid regulation correlated with wood degradation in four brown-rot fungi

Science.gov (United States)

Anne Christine Steenkjær Hastrup; Frederick Green III; Patricia K. Lebow; Bo Jensen

2012-01-01

Oxalic acid is a key component in the initiation of brown-rot decay and it has been suggested that it plays multiple roles during the degradation process. Oxalic acid is accumulated to varying degrees among brown-rot fungi; however, details on active regulation are scarce. The accumulation of oxalic acid was measured in this study from wood degraded by the four brown-...

Improving the enzymatic hydrolysis of thermo-mechanical fiber from Eucalyptus urophylla by a combination of hydrothermal pretreatment and alkali fractionation.

Science.gov (United States)

Sun, Shaoni; Cao, Xuefei; Sun, Shaolong; Xu, Feng; Song, Xianliang; Sun, Run-Cang; Jones, Gwynn Lloyd

2014-01-01

The recalcitrance of lignocellulosic biomass is a major limitation for its conversion into biofuels by enzymatic hydrolysis. The use of a pretreatment technology is an essential step to diminish biomass recalcitrance for bioethanol production. In this study, a two-step pretreatment using hydrothermal pretreatment at various temperatures and alkali fractionation was performed on eucalyptus fiber. The detailed chemical composition, physicochemical characteristics, and morphology of the pretreated fibers in each of the fractions were evaluated to advance the performance of eucalyptus fiber in enzymatic digestibility. The hydrothermal pretreatment (100 to 220°C) significantly degraded hemicelluloses, resulting in an increased crystallinity of the pretreated fibers. However, as the pretreatment temperature reached 240°C, partial cellulose was degraded, resulting in a reduced crystallinity of cellulose. As compared to the hydrothermal pretreatment alone, a combination of hydrothermal and alkali treatments significantly removed hemicelluloses and lignin, resulting in an improved enzymatic hydrolysis of the cellulose-rich fractions. As compared with the raw fiber, the enzymatic hydrolysis rate increased 1.1 to 8.5 times as the hydrothermal pretreatment temperature increased from 100 to 240°C. Interestingly, after a combination of hydrothermal pretreatment and alkali fractionation, the enzymatic hydrolysis rate increased 3.7 to 9.2 times. Taking into consideration the consumption of energy and the production of xylo-oligosaccharides and lignin, an optimum pretreatment condition was found to be hydrothermal pretreatment at 180°C for 30 min and alkali fractionation with 2% NaOH at 90°C for 2.5 h, in which 66.3% cellulose was converted into glucose by enzymatic hydrolysis. The combination of hydrothermal pretreatment and alkali fractionation was a promising method to remove hemicelluloses and lignin as well as overcome the biomass recalcitrance for enzymatic hydrolysis

Degradabilidade in situ de silagens de milho confeccionadas com inoculantes bacteriano e/ou enzimático - DOI: 10.4025/actascianimsci.v28i1.658 In situ degradability of corn silages prepared with bacterial and/or enzymatic inoculants - DOI: 10.4025/actascianimsci.v28i1.658

Directory of Open Access Journals (Sweden)

Elzânia Sales Pereira

2006-01-01

Full Text Available O objetivo deste trabalho foi avaliar os efeitos de inoculantes bacterianos e/ou enzimáticos sobre a degradabilidade ruminal da silagem de milho. Foi utilizada a técnica in situ, em quatro bovinos adultos, distribuídos em quadrado latino 4x4. Os tratamentos avaliados foram: SC (silagem controle, SIB (silagem com inoculante bacteriano, SIBE (silagem com inoculante bacteriano e enzimático e SIE (silagem com inoculante enzimático. Não houve diferença entre tratamentos nas frações solúvel (a, potencialmente degradável (b, taxa de degradação da fração b (c, degradabilidade potencial (DP e degradabilidade efetiva (DE da MS e MO. A DE da PB foi maior para o tratamento SIE (63,13% e menor para o tratamento SIBE (53,69%. A fração b da FDN apresentou maior valor para SIBE (74,13% e menor para SIB (64,07%. O resíduo indigerido (I da FDN não diferiu entre os tratamentos. As frações b e I e a taxa c da FDA não diferiram entre os tratamentos. Palavras-chave: degradação, fibra, matéria orgânica, matéria seca, proteína bruta.The objective of this work was to evaluate the effects of the bacterial and/or enzymatic inoculants on corn silage degradation. The in situ technique was used in four adult steers in a 4x4 latin square design. The evaluated treatments were: CS (control silage, SBI (silage with bacterial inoculant, SBEI (silage with bacterial and enzymatic inoculant and SEI (silage with enzymatic inoculant. There was no difference among treatments in soluble fraction (a, potential degradable fraction (b, fraction b rate of degradation (c, potential degradability (PD and effective degradability (ED of DM and OM. The ED of CP was higher in SEI treatment (63.13% and lower in SBEI treatment (53.69%. The b fraction of NDF was higher for SBEI (74.13% and lower for SBI (64.07%. The NDF indigestible residue (I did not show any difference among treatments. The ADF b and I fraction and the c rate values did not show any difference among

Effect of irradiation on enzymatic digestion of cellulosic wastes

International Nuclear Information System (INIS)

Chowdhury, N.A.; Matsuhashi, Shinpei; Hashimoto, Shoji; Kume, Tamikazu.

1993-03-01

Combination treatments with irradiation and other methods were examined to enhance the digestion of cellulosic materials such as sugar cane bagasse and rice straw. The amount of crude fiber (CF), acid detergent fiber (ADF) and neutral detergent fiber (NDF) of bagasse and rice straw were changed with various treatments. Alkali treatment (0.2N NaOH) was the most efficient for the enzymatic hydrolysis of bagasse and rice straw. Combination treatments with radiation and alkali or other methods increased their efficiency, and synergistic effect of radiation and alkali treatment was observed. Enzymatic digestion of CF of bagasse and rice straw treated by degassed water yielded high reducing sugar comparable to that of CF treated by alkali. CF of bagasse and rice straw treated by ozone did not show the significant increase in the release of reducing sugar upon saccharification. ADF and acid detergent lignin (ADL) contents decreased with the fermentation of bagasse by Coriolus versicolor. Electron microscopic observations also revealed the degradation of lignocellulosic components of bagasse. (author)

Exploration of the biomacromolecular interactions of an interpenetrating proteo-saccharide hydrogel network at the mucosal interface

CSIR Research Space (South Africa)

Mashingaidze, F

2013-09-01

Full Text Available EXPLORATION OF THE BIOMACROMOLECULAR INTERACTIONS OF AN INTERPENETRATING PROTEO-SACCHARIDE HYDROGEL NETWORK AT THE MUCOSAL INTERFACE 1Felix Mashingaidze, 1Yahya E. Choonara, 1Pradeep Kumar, 1Lisa C. du Toit, 2Vinesh Maharaj, 3Eckhart Buchmann, 4Valence M..., Department of Biosciences, Meiring Naud_e Road, Brummeria, Pretoria, South Africa 3University of the Witwatersrand, Faculty of Health Sciences, Department of Obstetrics and Gynecology, 7 York Road, Parktown, 2193, Johannesburg, South Africa 4St. John’s...

Glycerol-plasticised silk membranes made using formic acid are ductile, transparent and degradation-resistant.

Science.gov (United States)

Allardyce, Benjamin J; Rajkhowa, Rangam; Dilley, Rodney J; Redmond, Sharon L; Atlas, Marcus D; Wang, Xungai

2017-11-01

Regenerated silk fibroin membranes tend to be brittle when dry. The use of plasticisers such as glycerol improve membrane ductility, but, when combined with aqueous processing, can lead to a higher degradation rate than solvent-annealed membranes. This study investigated the use of formic acid as the solvent with glycerol to make deformable yet degradation-resistant silk membranes. Here we show that membranes cast using formic acid had low light scattering, with a diffuse transmittance of less than 5% over the visible wavelengths, significantly lower than the 20% transmittance of aqueous derived silk/glycerol membranes. They had 64% β-sheet content and lost just 30% of the initial silk weight over 6h when tested with an accelerated enzymatic degradation assay, in comparison the aqueous membranes completely degraded within this timeframe. The addition of glycerol also improved the maximum elongation of formic acid derived membranes from under 3% to over 100%. They also showed good cytocompatibility and supported the adhesion and migration of human tympanic membrane keratinocytes. Formic acid based, silk/glycerol membranes may be of great use in medical applications such as repair of tympanic membrane perforation or ocular applications where transparency and resistance to enzymatic degradation are important. Copyright © 2017 Elsevier B.V. All rights reserved.

Unique Chiral Interpenetrating d-f Heterometallic MOFs as Luminescent Sensors.

Science.gov (United States)

Wu, Zhi-Lei; Dong, Jie; Ni, Wei-Yan; Zhang, Bo-Wen; Cui, Jian-Zhong; Zhao, Bin

2015-06-01

One novel three-dimensional (3D) 3d-4f metal-organic framework (MOF), [TbZn(L)(CO3)2(H2O)]n (1) [HL = 4'-(4-carboxyphenyl)-2,2':6',2″-terpyridine], has been successfully synthesized and structurally characterized. Structural analysis shows that compound 1 features a unique chiral interpenetrating 3D framework for the first time. The resulting crystals of 1 are composed of enantiomers 1a (P41) and 1b (P43), as was clearly confirmed by the crystal structure and the corresponding circular dichroism (CD) analyses of eight randomly selected crystals. The investigations on CD spectra based on every single crystal clearly assigned the Cotton effect signals. The powder X-ray diffraction measurement of 1 after being immersed in common solvents reveals that 1 possess excellent solvent stability. Furthermore, luminescent studies imply that 1 displays highly selective luminescent sensing of aldehydes, such as formol, acetaldehyde, and propanal.

System with embedded drug release and nanoparticle degradation sensor showing efficient rifampicin delivery into macrophages.

Science.gov (United States)

Trousil, Jiří; Filippov, Sergey K; Hrubý, Martin; Mazel, Tomáš; Syrová, Zdeňka; Cmarko, Dušan; Svidenská, Silvie; Matějková, Jana; Kováčik, Lubomír; Porsch, Bedřich; Konefał, Rafał; Lund, Reidar; Nyström, Bo; Raška, Ivan; Štěpánek, Petr

2017-01-01

We have developed a biodegradable, biocompatible system for the delivery of the antituberculotic antibiotic rifampicin with a built-in drug release and nanoparticle degradation fluorescence sensor. Polymer nanoparticles based on poly(ethylene oxide) monomethyl ether-block-poly(ε-caprolactone) were noncovalently loaded with rifampicin, a combination that, to best of our knowledge, was not previously described in the literature, which showed significant benefits. The nanoparticles contain a Förster resonance energy transfer (FRET) system that allows real-time assessment of drug release not only in vitro, but also in living macrophages where the mycobacteria typically reside as hard-to-kill intracellular parasites. The fluorophore also enables in situ monitoring of the enzymatic nanoparticle degradation in the macrophages. We show that the nanoparticles are efficiently taken up by macrophages, where they are very quickly associated with the lysosomal compartment. After drug release, the nanoparticles in the cmacrophages are enzymatically degraded, with half-life 88±11 min. Copyright © 2016 Elsevier Inc. All rights reserved.

Arbuscular mycorrhizal fungi in a semi-arid, limestone mining-impacted area of Brazil

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Thaís Teixeira-Rios

2013-12-01

Full Text Available The main goal of this study was to determine the diversity and activity of arbuscular mycorrhizal fungi (AMF in an area degraded by limestone mining within the semi-arid region of Brazil known as the caatinga (shrublands. Near a limestone quarry, we selected two areas of caatinga (preserved and degraded for study. The number of glomerospores did not differ significantly between the two areas. There was a trend toward the most probable number of infective propagules being higher in the degraded area. Twenty AMF taxa were identified in the two sampled areas, species richness, diversity and evenness being higher in the preserved area. Two species of Racocetra represent new records for the semi-arid region of Brazil. Glomerospore production and AMF species richness were unaffected by mining activity in the study area.

Increased saccharification yields from aspen biomass upon treatment with enzymatically generated peracetic acid.

Science.gov (United States)

Duncan, Shona; Jing, Qing; Katona, Adrian; Kazlauskas, Romas J; Schilling, Jonathan; Tschirner, Ulrike; Aldajani, Waleed Wafa

2010-03-01

The recalcitrance of lignocellulosic biomass to enzymatic release of sugars (saccharification) currently limits its use as feedstock for biofuels. Enzymatic hydrolysis of untreated aspen wood releases only 21.8% of the available sugars due primarily to the lignin barrier. Nature uses oxidative enzymes to selectively degrade lignin in lignocellulosic biomass, but thus far, natural enzymes have been too slow for industrial use. In this study, oxidative pretreatment with commercial peracetic acid (470 mM) removed 40% of the lignin (from 19.9 to 12.0 wt.% lignin) from aspen and enhanced the sugar yields in subsequent enzymatic hydrolysis to about 90%. Increasing the amount of lignin removed correlated with increasing yields of sugar release. Unfortunately, peracetic acid is expensive, and concentrated forms can be hazardous. To reduce costs and hazards associated with using commercial peracetic acid, we used a hydrolase to catalyze the perhydrolysis of ethyl acetate generating 60-70 mM peracetic acid in situ as a pretreatment to remove lignin from aspen wood. A single pretreatment was insufficient, but multiple cycles (up to eight) removed up to 61.7% of the lignin enabling release of >90% of the sugars during saccharification. This value corresponds to a predicted 581 g of fermentable sugars from 1 kg of aspen wood. Improvements in the enzyme stability are needed before the enzymatically generated peracetic acid is a commercially viable alternative.

Interpenetration and deflection phenomena in collisions between supersonic, magnetized, tungsten plasma flows diagnosed using high resolution optical Thomson scattering

Energy Technology Data Exchange (ETDEWEB)

Swadling, G. F.; Lebedev, S. V.; Burdiak, G.; Suttle, L.; Patankar, S.; Smith, R. A.; Bennett, M.; Hall, G. N.; Suzuki-Vidal, F.; Bland, S. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Harvey-Thompson, A. J. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1193 (United States); Rozmus, W. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Yuan, J. [Key Laboratory of Pulsed Power, Institute of Fluid Physics, CAE, Mianyang 621900 (China)

2015-07-15

An optical Thomson scattering diagnostic has been used to investigate collisions between supersonic, magnetized plasma flows, in particular the transition from collisionless to collisional interaction dynamics. These flows were produced using tungsten wire array z-pinches, driven by the 1.4 MA 240 ns Magpie generator at Imperial College London. Measurements of the collective-mode Thomson scattering ion-feature clearly indicate that the ablation flows are interpenetrating at 100 ns (after current start), and this interpenetration continues until at least 140 ns. The Thomson spectrum at 150 ns shows a clear change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streams near the axis. The Thomson scattering data also provide indirect evidence of the presence of a significant toroidal magnetic field embedded in the “precursor” plasma near the axis of the array over the period 100–140 ns; these observations are in agreement with previous measurements [Swadling et al., Phys. Rev. Lett. 113, 035003 (2014)]. The Thomson scattering measurements at 150 ns suggest that this magnetic field must collapse at around the time the dense precursor column begins to form.

Post-genomic analyses of fungal lignocellulosic biomass degradation reveal the unexpected potential of the plant pathogen Ustilago maydis

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Couturier Marie

2012-02-01

Full Text Available Abstract Background Filamentous fungi are potent biomass degraders due to their ability to thrive in ligno(hemicellulose-rich environments. During the last decade, fungal genome sequencing initiatives have yielded abundant information on the genes that are putatively involved in lignocellulose degradation. At present, additional experimental studies are essential to provide insights into the fungal secreted enzymatic pools involved in lignocellulose degradation. Results In this study, we performed a wide analysis of 20 filamentous fungi for which genomic data are available to investigate their biomass-hydrolysis potential. A comparison of fungal genomes and secretomes using enzyme activity profiling revealed discrepancies in carbohydrate active enzymes (CAZymes sets dedicated to plant cell wall. Investigation of the contribution made by each secretome to the saccharification of wheat straw demonstrated that most of them individually supplemented the industrial Trichoderma reesei CL847 enzymatic cocktail. Unexpectedly, the most striking effect was obtained with the phytopathogen Ustilago maydis that improved the release of total sugars by 57% and of glucose by 22%. Proteomic analyses of the best-performing secretomes indicated a specific enzymatic mechanism of U. maydis that is likely to involve oxido-reductases and hemicellulases. Conclusion This study provides insight into the lignocellulose-degradation mechanisms by filamentous fungi and allows for the identification of a number of enzymes that are potentially useful to further improve the industrial lignocellulose bioconversion process.

H2O2-induced higher order chromatin degradation: A novel ...

Indian Academy of Sciences (India)

Unknown

mediator of oxidative stress, can also cause genomic damage indirectly. Thus, H2O2 at pathologically relevant concentrations rapidly induces higher order chromatin degradation (HOCD), i.e. enzymatic ... clease works through a single strand scission mechanism ... a great mutagenic risk to the surviving cells, because en-.

Cassava Pulp as a Biofuel Feedstock of an Enzymatic Hydrolysis Proces

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Djuma’ali Djuma’ali

2013-03-01

Full Text Available Cassava pulp, a low cost solid byproduct of cassava starch industry, has been proposed as a high potential ethanolic fermentation substrate due to its high residual starch level, low ash content and small particle size of the lignocellulosic fibers. As the economic feasibility depends on complete degradation of the polysaccharides to fermentable glucose, the comparative hydrolytic potential of cassava pulp by six commercial enzymes were studied. Raw cassava pulp (12% w/v, particle size <320 μm hydrolyzed by both commercial pectinolytic (1 and amylolytic (2 enzymes cocktail, yielded 70.06% DE. Hydrothermal treatment of cassava pulp enhanced its susceptibility to enzymatic cleavageas compared to non-hydrothermal treatment raw cassava pulp. Hydrothermal pretreatment has shown that a glucoamylase (3 was the most effective enzyme for hydrolysis process of cassava pulp at temperature 65 °C or 95 °C for 10 min and yielded approximately 86.22% and 90.18% DE, respectively. Enzymatic pretreatment increased cassava pulp vulnerability to cellulase attacks. The optimum conditions for enzymatic pretreatment of 30% (w/v cassava pulp by a potent cellulolytic/ hemicellulolytic enzyme (4 was achieves at 50 °C for 3, meanwhile for liquefaction and saccharification by a thermo-stable α-amylase (5 was achieved at 95 °C for 1 and a glucoamylase (3 at 50 °C for 24 hours, respectively, yielded a reducing sugar level up to 94,1% DE. The high yield of glucose indicates the potential use of enzymatic-hydrothermally treated cassava pulp as a cheap substrate for ethanol production.

Enzymatic degradation of in vitro Staphylococcus aureus biofilms supplemented with human plasma

Directory of Open Access Journals (Sweden)

Watters CM

2016-04-01

Full Text Available Chase M Watters,1,2 Tarea Burton,1 Dickson K Kirui,1 Nancy J Millenbaugh1 1Maxillofacial Injury and Disease Department, Naval Medical Research Unit San Antonio, Joint Base San Antonio-Fort Sam Houston, TX, USA; 2Wound Infections Department, Naval Medical Research Center, Silver Spring, MD, USA Abstract: Enzymatic debridement is a therapeutic strategy used clinically to remove necrotic tissue from wounds. Some of the enzymes utilized for debridement have been tested against bacterial pathogens, but the effectiveness of these agents in dispersing clinically relevant biofilms has not been fully characterized. Here, we developed an in vitro Staphylococcus aureus biofilm model that mimics wound-like conditions and employed this model to investigate the antibiofilm activity of four enzymatic compounds. Human plasma at concentrations of 0%–50% was supplemented into growth media and used to evaluate biofilm biomass accumulation over 24 hours and 48 hours in one methicillin-sensitive and five methicillin-resistant strains of S. aureus. Supplementation of media with 10% human plasma resulted in the most robust biofilms in all six strains. The enzymes α-amylase, bromelain, lysostaphin, and papain were then tested against S. aureus biofilms cultured in 10% human plasma. Quantification of biofilms after 2 hours and 24 hours of treatment using the crystal violet assay revealed that lysostaphin decreased biomass by up to 76%, whereas a-amylase, bromelain, and papain reduced biomass by up to 97%, 98%, and 98%, respectively. Scanning electron microscopy confirmed that the dispersal agents detached the biofilm exopolysaccharide matrix and bacteria from the growth surface. Lysostaphin caused less visible dispersal of the biofilms, but unlike the other enzymes, induced morphological changes indicative of bacterial cell damage. Overall, our results indicate that use of enzymes may be an effective means of eradicating biofilms and a promising strategy to improve

Novel 3D porous semi-IPN hydrogel scaffolds of silk sericin and poly(N-hydroxyethyl acrylamide for dermal reconstruction

Directory of Open Access Journals (Sweden)

S. Ross

2017-09-01

Full Text Available In this work, a novel semi-interpenetrating polymer network (semi-IPN hydrogel scaffold based on silk sericin (SS and poly(N-hydroxyethyl acrylamide (PHEA was successfully fabricated via conventional free-radical polymerization. The porous structure of the scaffolds was introduced using a lyophilization technique and the effect of cross-linker (XL on morphology, gelation time and physical properties of hydrogel scaffold was first studied. The results show that using low cross-linker content (0.125, 0.25 and 0.5 wt% XL produced flexible scaffolds and appropriate gelation times for fabricating the scaffold. Therefore, the polymerization system with a constant percentage of XL at 0.5 wt% was chosen to study further the effect of SS on the physical properties and cell culture of the scaffolds. It was observed that the hydrogel scaffold of PHEA without SS (PHEA/SS-0 had no cell proliferation, whereas hydrogel scaffolds with SS enhanced cell viability when compared to the positive control. The sample of PHEA/SS at 1.25 wt% of SS and 0.5 wt% of cross-linker was the most suitable for HFF-1 cells to migrate and cell proliferation due to possessing a connective porous structure, along with silk sericin. The results proved that this novel porous semi-IPN hydrogel has the potential to be used as dermal reconstruction scaffold.

Mathematical and numerical analysis of a multi-velocity multi-fluid model for interpenetration of miscible fluids; Analyse mathematique et numerique d'un modele multifluide multivitesse pour l'interpenetration de fluides miscibles

Energy Technology Data Exchange (ETDEWEB)

Enaux, C

2007-11-15

The simulation of indirect laser implosion requires an accurate knowledge of the inter-penetration of the laser target materials turned into plasma. This work is devoted to the study of a multi-velocity multi-fluid model recently proposed by Scannapieco and Cheng (SC) to describe the inter-penetration of miscible fluids. In this document, we begin with presenting the SC model in the context of miscible fluids flow modelling. Afterwards, the mathematical analysis of the model is carried out (study of the hyperbolicity, existence of a strictly convex mathematical entropy, asymptotic analysis and diffusion limit). As a conclusion the problem is well set. Then, we focus on the problem of numerical resolution of systems of conservation laws with a relaxation source term, because SC model belongs to this class. The main difficulty of this task is to capture on a coarse grid the asymptotic behaviour of the system when the source term is stiff. The main contribution of this work lies in the proposition of a new technique, allowing us to construct a Lagrangian numerical flux taking into account the presence of the source term. This technique is applied first on the model-problem of a one-dimensional Euler system with friction, and then on the multi-fluid SC model. In both cases, we prove that the new scheme is asymptotic-preserving and entropic under a CFL-like condition. The two-dimensional extension of the scheme is done by using a standard alternate directions method. Some numerical results highlight the contribution of the new flux, compared with a standard Lagrange plus Remap scheme where the source term is processed using an operator splitting. (author)

Understanding interpenetrating-polymer-network-like porous nitrile butadiene rubber hybrids by their long-period miscibility

International Nuclear Information System (INIS)

Zhang, Jihua; Wang, Lifeng; Zhao, Yunfeng

2013-01-01

Highlights: • Hydrogen bonds are introduced into NBR to develop its IPN-like porous hybrids. • NBR is partly miscible with AO-60. • AO-60 possesses the viscoelastic behavior resembling that of polymers. • Phase separation aggravates and AO-60 crystallizes in the durations. • The porous hybrids may have potential damping applications. - Abstract: In this article, tetrakis [methylene-3-(3, 5-di-tert-butyl-4-hydroxy phenyl) propionyloxy] methane (AO-60) with hydrogen bonds was designed to interpenetrate into the chemical crosslinking bonds of nitrile butadiene rubber (NBR) and then porous materials were prepared. Scanning electron microscopy (SEM), atomic force microscopy (AFM) images and dynamic mechanical analyses (DMA) demonstrate that NBR is partly miscible with AO-60 which induces the micro-pores and interpenetrating-polymer-network (IPN)-like phase morphology in the hybrids. The wide double tan δ peak in DMA curve displays that AO-60 possesses similar viscoelastic behaviors to polymers which come from supramolecular interactions between polar groups of NBR chains and hydroxyl (OH) groups of AO-60. To further understand the supramolecular abilities of AO-60 in the rubber, the long-period observations for their miscibility are conducted. With the increase of durations, the hydrogen bond network from AO-60 is weakened. The phase separation between AO-60 and NBR is aggravated and even extremely few AO-60 crystallizes which develops multi-scale porous morphology in the hybrids. It is believed that these findings can serve as a guide for the designs of the IPN-like hybrids with small molecule substances and their applications of damping materials

Effect and Modeling of Glucose Inhibition and In Situ Glucose Removal During Enzymatic Hydrolysis of Pretreated Wheat Straw

DEFF Research Database (Denmark)

Andric, Pavle; Meyer, Anne S.; Jensen, Peter Arendt

2010-01-01

The enzymatic hydrolysis of lignocellulosic biomass is known to be product-inhibited by glucose. In this study, the effects on cellulolytic glucose yields of glucose inhibition and in situ glucose removal were examined and modeled during extended treatment of heat-pretreated wheat straw......, during 96 h of reaction. When glucose was removed by dialysis during the enzymatic hydrolysis, the cellulose conversion rates and glucose yields increased. In fact, with dialytic in situ glucose removal, the rate of enzyme-catalyzed glucose release during 48-72 h of reaction recovered from 20......-40% to become approximate to 70% of the rate recorded during 6-24 h of reaction. Although Michaelis-Menten kinetics do not suffice to model the kinetics of the complex multi-enzymatic degradation of cellulose, the data for the glucose inhibition were surprisingly well described by simple Michaelis...

Nano-Scale Interpenetrating Phase Composites (IPC S) for Industrial and Vehicle Applications

Energy Technology Data Exchange (ETDEWEB)

Hemrick, James Gordon [ORNL; Hu, Michael Z. [ORNL

2010-06-01

A one-year project was completed at Oak Ridge National Laboratory (ORNL) to explore the technical and economic feasibility of producing nano-scale Interpenetrating Phase Composite (IPC) components of a usable size for actual testing/implementation in a real applications such as high wear/corrosion resistant refractory shapes for industrial applications, lightweight vehicle braking system components, or lower cost/higher performance military body and vehicle armor. Nano-scale IPC s with improved mechanical, electrical, and thermal properties have previously been demonstrated at the lab scale, but have been limited in size. The work performed under this project was focused on investigating the ability to take the current traditional lab scale processes to a manufacturing scale through scaling of these processes or through the utilization of an alternative high-temperature process.

CFA-7: an interpenetrated metal-organic framework of the MFU-4 family.

Science.gov (United States)

Schmieder, Phillip; Grzywa, Maciej; Denysenko, Dmytro; Hambach, Manuel; Volkmer, Dirk

2015-08-07

The novel interpenetrated metal-organic framework CFA-7 (Coordination Framework Augsburg University-7), [Zn5Cl4(tqpt)3], has been synthesized containing the organic linker {H2-tqpt = 6,6,14,14-tetramethyl-6,14-dihydroquinoxalino[2,3-b]phenazinebistriazole}. Reaction of H2-tqpt and anhydrous ZnCl2 in N,N-dimethylformamide (DMF) yields CFA-7 as pseudo-cubic crystals. CFA-7 serves as precursor for the synthesis of isostructural frameworks with redox-active metal centers, which is demonstrated by postsynthetic metal exchange of Zn(2+) by different M(2+) (M = Co, Ni, Cu) ions. The novel framework is robust upon solvent removal and has been structurally characterized by single-crystal X-ray diffraction, TGA and IR spectroscopy, as well as gas sorption (Ar, CO2 and H2).

Interpenetrating network ceramic-resin composite dental restorative materials.

Science.gov (United States)

Swain, M V; Coldea, A; Bilkhair, A; Guess, P C

2016-01-01

This paper investigates the structure and some properties of resin infiltrated ceramic network structure materials suitable for CAD/CAM dental restorative applications. Initially the basis of interpenetrating network materials is defined along with placing them into a materials science perspective. This involves identifying potential advantages of such structures beyond that of the individual materials or simple mixing of the components. Observations from a number of recently published papers on this class of materials are summarized. These include the strength, fracture toughness, hardness and damage tolerance, namely to pointed and blunt (spherical) indentation as well as to burr adjustment. In addition a summary of recent results of crowns subjected to simulated clinical conditions using a chewing simulator are presented. These results are rationalized on the basis of existing theoretical considerations. The currently available ceramic-resin IPN material for clinical application is softer, exhibits comparable strength and fracture toughness but with substantial R-curve behavior, has lower E modulus and is more damage tolerant than existing glass-ceramic materials. Chewing simulation observations with crowns of this material indicate that it appears to be more resistant to sliding/impact induced cracking although its overall contact induced breakage load is modest. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Fungal Laccases Degradation of Endocrine Disrupting Compounds

Directory of Open Access Journals (Sweden)

Gemma Macellaro

2014-01-01

Full Text Available Over the past decades, water pollution by trace organic compounds (ng/L has become one of the key environmental issues in developed countries. This is the case of the emerging contaminants called endocrine disrupting compounds (EDCs. EDCs are a new class of environmental pollutants able to mimic or antagonize the effects of endogenous hormones, and are recently drawing scientific and public attention. Their widespread presence in the environment solicits the need of their removal from the contaminated sites. One promising approach to face this challenge consists in the use of enzymatic systems able to react with these molecules. Among the possible enzymes, oxidative enzymes are attracting increasing attention because of their versatility, the possibility to produce them on large scale, and to modify their properties. In this study five different EDCs were treated with four different fungal laccases, also in the presence of both synthetic and natural mediators. Mediators significantly increased the efficiency of the enzymatic treatment, promoting the degradation of substrates recalcitrant to laccase oxidation. The laccase showing the best performances was chosen to further investigate its oxidative capabilities against micropollutant mixtures. Improvement of enzyme performances in nonylphenol degradation rate was achieved through immobilization on glass beads.

Interpenetrating Polymer Network Hydrogels Based on Gelatin and PVA by Biocompatible Approaches: Synthesis and Characterization

Directory of Open Access Journals (Sweden)

Eltjani-Eltahir Hago

2013-01-01

Full Text Available In this work, a new approach was introduced to prepare interpenetrating polymer network PVA/GE hydrogels by cross-linking of various concentration gelatin in the presence of transglutaminase enzyme by using the freezing-thawing cycles technique. The effects of freezing-thawing cycles on the properties of morphological characterization, gel fraction, swelling, mechanical, and MTT assay were investigated. The IPN PVA/GE hydrogels showed excellent physical and mechanical Properties. MTT assay data and the fibroblasts culture also showed excellent biocompatibility and good proliferation. This indicates that the IPN hydrogels are stable enough for various biomedical applications.

Synthesis and characterization of poly (n-butyl acrylate)-poly (methyl methacrylate) latex interpenetrating polymer networks by radiation-induced seeded emulsion polymerization

Energy Technology Data Exchange (ETDEWEB)

Yu Haibo [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Peng Jing [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: jpeng@pku.edu.cn; Zhai Maolin; Li Jiuqiang; Wei Genshuan [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Qiao Jinliang [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); SINOPEC Beijing Research Institute of Chemical Industry, Beijing 100013 (China)

2007-11-15

A series of latex interpenetrating polymer networks (LIPNs) were prepared via a two-stage emulsion polymerization of methyl methacrylate (MMA) or mixture of MMA and n-butyl acrylate (n-BA) on crosslinked poly(n-butyl acrylate)(PBA) seed latex using {sup 60}Co {gamma}-ray radiation. The particles of resultant latex were produced with diameters between 150 and 250 nm. FTIR spectra identified the formation of crosslinked copolymers of PMMA or P(MMA-co-BA). Dynamic light scattering (DLS) showed that with increasing n-BA concentration in second-stage monomers, the particle size of LIPN increased. Transmission electron microscope(TEM) photographs showed that the morphology of resultant acrylate interpenetrating polymer network (IPN) latex varied from the distinct core-shell structure to homogenous particle structure with the increase of n-BA concentration, and the morphology was mainly controlled by the miscibility between crosslinked PBA seed and second-stage copolymers and polarity of P(MMA-co-BA)copolymers. In addition, differential scanning calorimeter (DSC) measurements indicated the existence of reinforced miscibility between PBA seed and P(MMA-co-BA)copolymer in prepared LIPNs.

Vitamin C. Biosynthesis, recycling and degradation in mammals.

Science.gov (United States)

Linster, Carole L; Van Schaftingen, Emile

2007-01-01

Vitamin C, a reducing agent and antioxidant, is a cofactor in reactions catalyzed by Cu(+)-dependent monooxygenases and Fe(2+)-dependent dioxygenases. It is synthesized, in vertebrates having this capacity, from d-glucuronate. The latter is formed through direct hydrolysis of uridine diphosphate (UDP)-glucuronate by enzyme(s) bound to the endoplasmic reticulum membrane, sharing many properties with, and most likely identical to, UDP-glucuronosyltransferases. Non-glucuronidable xenobiotics (aminopyrine, metyrapone, chloretone and others) stimulate the enzymatic hydrolysis of UDP-glucuronate, accounting for their effect to increase vitamin C formation in vivo. Glucuronate is converted to l-gulonate by aldehyde reductase, an enzyme of the aldo-keto reductase superfamily. l-Gulonate is converted to l-gulonolactone by a lactonase identified as SMP30 or regucalcin, whose absence in mice leads to vitamin C deficiency. The last step in the pathway of vitamin C synthesis is the oxidation of l-gulonolactone to l-ascorbic acid by l-gulonolactone oxidase, an enzyme associated with the endoplasmic reticulum membrane and deficient in man, guinea pig and other species due to mutations in its gene. Another fate of glucuronate is its conversion to d-xylulose in a five-step pathway, the pentose pathway, involving identified oxidoreductases and an unknown decarboxylase. Semidehydroascorbate, a major oxidation product of vitamin C, is reconverted to ascorbate in the cytosol by cytochrome b(5) reductase and thioredoxin reductase in reactions involving NADH and NADPH, respectively. Transmembrane electron transfer systems using ascorbate or NADH as electron donors serve to reduce semidehydroascorbate present in neuroendocrine secretory vesicles and in the extracellular medium. Dehydroascorbate, the fully oxidized form of vitamin C, is reduced spontaneously by glutathione, as well as enzymatically in reactions using glutathione or NADPH. The degradation of vitamin C in mammals is

Forests and water - Friends or foes?. Hydrological implications of deforestation and land degradation in semi-arid Tanzania

International Nuclear Information System (INIS)

Sandstroem, K.

1995-01-01

In the study area in Babati District in Tanzania a multi-component research approach was attempted. Two catchments, one forested and one deforested-degraded, were studied regarding soil properties, runoff and groundwater recharge. This was done both in the field and with the use of two computer models: one simulating groundwater recharge as a function of rainfall variability, and one simulating hydrological implications of massive land cover conversion on the flooding of nearby Lake Babati. Three major findings came out of the study. The first is that most forested catchments (in various hydroclimates and landscapes) will increase the runoff following deforestation (due to less evapotranspiration). This is well-established knowledge, but it also depends on the actual conditions at hand. These conditions are defined as hydroclimate, soil texture and slope. In humid-temperate climates with coarse soils on flat land, the conditions strongly favor increased runoff following deforestation. However, in dry regions with fine textured soils on hilly ground, and where deforestation also implies land degradation, less dry season flow is likely to develop after a considerable adjustment period has been allowed. Secondly, the prevalence of preferential flow in a forest soil, as compared to a compacted and eroded soil, must be a key component in an explanation of why more dry season flow can emerge from a forested as compared to a deforested catchment in the dry tropics. Thirdly, there are several aspects of semi-arid and arid tropical hydrology which make comparisons with humid-temperate regions difficult and require special attention in the management of water resources in the dry tropics. 14 refs, 18 figs, 1 tab

Dilute H{sub 2}SO{sub 4}-catalyzed hydrothermal pretreatment to enhance enzymatic digestibility of Jatropha curcas fruit hull for ethanol fermentation

Energy Technology Data Exchange (ETDEWEB)

Marasabessy, Ahmad [Wageningen Univ. (Netherlands). Agrotechnology and Food Sciences Group; Rijksuniversiteit Groningen (Netherlands). Dept. of Chemical Engineering; Agency for the Assessment and Application of Technology (BPPT), Jakarta (Indonesia); Kootstra, A. Maarten J. [Wageningen Univ. (Netherlands). Agrotechnology and Food Sciences Group; Wageningen Univ. (Netherlands). Bioprocess Engineering Group; Sanders, Johan P.M.; Westhuis, Ruud A. [Wageningen Univ. (Netherlands). Agrotechnology and Food Sciences Group

2012-11-01

Dilute sulfuric acid pretreatment of the Jatropha curcas fruit hull at high temperatures (140 C to 180 C) performed in a 110-mL stainless steel reactor was investigated to enhance the enzymatic digestibility of its lignocellulosic components. Carbohydrates accounted for 43% of the dry matter of the J. curcas fruit hull biomass. The goal of the study was to optimize the pretreatment conditions (acid concentration, time, and temperature) in order to obtain the highest sugar yield after subsequent enzymatic hydrolysis. A Box-Behnken design was applied to the experimental setup in order to reduce the number of experiments. The optimal pretreatment conditions are 30-min incubations at a temperature of 178 C with a sulfuric acid concentration of 0.9% (w/v). Using these pretreatment conditions for a fruit solid loading of 9.52% followed by a 24-h enzymatic hydrolysis resulted in a liberation of 100% of all pentoses present (71% yield and 29% degradation to furfural) and 83% of the hexoses (78% yield and 5% degradation to 5-hydroxymethylfurfural). The simultaneous saccharification and fermentation experiment showed that acid-pretreated fruit hull can be used as a substrate for Saccharomyces cerevisiae to produce ethanol. (orig.)

Enzymatically Degradable Hybrid Organic-Inorganic Bridged Silsesquioxane Nanoparticles for In-Vitro Imaging

KAUST Repository

Fatieiev, Yevhen; Croissant, Jonas G.; Julfakyan, Khachatur; Deng, Lin; Anjum, Dalaver H.; Gurinov, Andrei; Khashab, Niveen M.

2015-01-01

Non-aggregated dense bridged silsesquioxane (BS) nanoparticles based on nature-inspired oxamide bridges are shown to degrade in simulated biological media upon cleavage with endopeptidase. Fluorescent BS nanoprobes with incorporated fluorescein dyes

Radiation degration and the subsequent enzymatic hydrolysis of waste papers

International Nuclear Information System (INIS)

Kamakura, M.; Kaetsu, I.

1982-01-01

In recent years, many methods have been proposed for the hydrolysis of waste cellulose to utilize it as a new source of alcohol. Because it is difficult to hydrolyze waste cellulosic materials effectivley with an enzyme, the effects of preirradiating waste papers on subsequent enzymatic hydrolysis was studied. Preirradiation (x rays from 60 Co) accelerated the hydrolysis rate of newspaper by cellulase and the reducing-sugar yield increased with increasing irradiation dose. It is thought that preirradiation probably contributes to loosening and releasing the compactly entangled structure of cellulose and lignin in the materials by radiation degradation

Degradation-by-design: Surface modification with functional substrates that enhance the enzymatic degradation of carbon nanotubes.

Science.gov (United States)

Sureshbabu, Adukamparai Rajukrishnan; Kurapati, Rajendra; Russier, Julie; Ménard-Moyon, Cécilia; Bartolini, Isacco; Meneghetti, Moreno; Kostarelos, Kostas; Bianco, Alberto

2015-12-01

Biodegradation of carbon-based nanomaterials has been pursued intensively in the last few years, as one of the most crucial issues for the design of safe, clinically relevant conjugates for biomedical applications. In this paper it is demonstrated that specific functional molecules can enhance the catalytic activity of horseradish peroxidase (HRP) and xanthine oxidase (XO) for the degradation of carbon nanotubes. Two different azido coumarins and one cathecol derivative are linked to multi-walled carbon nanotubes (MWCNTs). These molecules are good reducing substrates and strong redox mediators to enhance the catalytic activity of HRP. XO, known to metabolize various molecules mainly in the mammalian liver, including human, was instead used to test the biodegradability of MWCNTs modified with an azido purine. The products of the biodegradation process are characterized by transmission electron microscopy and Raman spectroscopy. The results indicate that coumarin and catechol moieties have enhanced the biodegradation of MWCNTs compared to oxidized nanotubes, likely due to the capacity of these substrates to better interact with and activate HRP. Although azido purine-MWCNTs are degraded less effectively by XO than oxidized nanotubes, the data uncover the importance of XO in the biodegradation of carbon-nanomaterials leading to their better surface engineering for biomedical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of sodium carbonate pretreatment on the chemical compositions and enzymatic saccharification of rice straw.

Science.gov (United States)

Yang, Linfeng; Cao, Jie; Jin, Yongcan; Chang, Hou-min; Jameel, Hasan; Phillips, Richard; Li, Zhongzheng

2012-11-01

The effects of sodium carbonate (Na(2)CO(3)) pretreatment on the chemical compositions and enzymatic saccharification of rice straw were investigated. The enzymatic digestibility of rice straw is enhanced after pretreatment since pretreated solids show significant delignification with high sugar availability. During pretreatment, an increasing temperature and Na(2)CO(3) charge leads to enhanced delignification, whereas an increased degradation of polysaccharides as well, of which xylan acts more susceptible than glucan. The sugar recovery of enzymatic hydrolysis goes up rapidly with the total titratable alkali (TTA) increasing from 0% to 8%, and then it reaches a plateau. The highest sugar recovery of rice straw after pretreatment, 71.7%, 73.2%, and 76.1% for total sugar, glucan, and xylan, respectively, is obtained at 140°C, TTA 8% and cellulase loading of 20 FPU/g-cellulose. In this condition, the corresponding delignification ratio of pretreated solid is 41.8%, while 95% of glucan and 76% of xylan are conserved. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Paleozoic origin of enzymatic mechanisms for lignin degradation reconstructed using 31 fungal genomes

Energy Technology Data Exchange (ETDEWEB)

Floudas, Dimitrios; Binder, Manfred; Riley, Robert; Barry, Kerrie; Blanchette, Robert A; Henrissat, Bernard; Martinez, Angel T.; Otillar, Robert; Spatafora, Joseph W.; Yadav, Jagit S.; Aerts, Andrea; Benoit, Isabelle; Boyd, Alex; Carlson, Alexis; Copeland, Alex; Coutinho, Pedro M.; de Vries, Ronald P.; Ferreira, Patricia; Findley, Keisha; Foster, Brian; Gaskell, Jill; Glotzer, Dylan; Gorecki, Pawel; Heitman, Joseph; Hesse, Cedar; Hori, Chiaki; Igarashi, Kiyohiko; Jurgens, Joel A.; Kallen, Nathan; Kersten, Phil; Kohler, Annegret; Kues, Ursula; Kumar, T. K. Arun; Kuo, Alan; LaButti, Kurt; Larrondo, Luis F.; Lindquist, Erika; Ling, Albee; Lombard, Vincent; Lucas, Susan; Lundell, Taina; Martin, Rachael; McLaughlin, David J.; Morgenstern, Ingo; Morin, Emanuelle; Murat, Claude; Nagy, Laszlo G.; Nolan, Matt; Ohm, Robin A.; Patyshakuliyeva, Aleksandrina; Rokas, Antonis; Ruiz-Duenas, Francisco J.; Sabat, Grzegorz; Salamov, Asaf; Samejima, Masahiro; Schmutz, Jeremy; Slot, Jason C.; John, Franz; Stenlid, Jan; Sun, Hui; Sun, Sheng; Syed, Khajamohiddin; Tsang, Adrian; Wiebenga, Ad; Young, Darcy; Pisabarro, Antonio; Eastwood, Daniel C.; Martin, Francis; Cullen, Dan; Grigoriev, Igor V.; Hibbett, David S.

2012-03-12

Wood is a major pool of organic carbon that is highly resistant to decay, owing largely to the presence of lignin. The only organisms capable of substantial lignin decay are white rot fungi in the Agaricomycetes, which also contains non?lignin-degrading brown rot and ectomycorrhizal species. Comparative analyses of 31 fungal genomes (12 generated for this study) suggest that lignin-degrading peroxidases expanded in the lineage leading to the ancestor of the Agaricomycetes, which is reconstructed as a white rot species, and then contracted in parallel lineages leading to brown rot and mycorrhizal species. Molecular clock analyses suggest that the origin of lignin degradation might have coincided with the sharp decrease in the rate of organic carbon burial around the end of the Carboniferous period.

In vitro degradation of dermal sheep collagen cross-linked using a water-soluble carbodiimide

NARCIS (Netherlands)

Damink, LHHO; Dijkstra, PJ; vanLuyn, MJA; vanWachem, PB; Nieuwenhuis, P; Feijen, J

Bacterial collagenase was used to study the susceptibility of dermal sheep collagen (DSC) cross-inked with a mixture of the water-soluble carbodiimide 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide (EIN-DSC) towards enzymatic degradation. Contrary to

Functional bio-based polyesters by enzymatic polymerization

DEFF Research Database (Denmark)

Daugaard, Anders Egede; Hoffmann, Christian; Andersen, Christian

During recent years enzymatic polymerization has become increasingly popular as an alternative to classical polyesterification processes. The high regioselectivity observed for lipases permits preparation of novel polyesters with a high number of functional groups.1 This is particularly interesting...... polymerization was applied to prepare functional water soluble polyesters based on dimethyl itaconate and poly(ethyleneglycol).2 The monomer permits postfunctionalization using thiol-ene chemistry or aza-michael additions, which was used to illustrate the possibilites of preparing functional hydrogels. Hydrogels...... based on the polyesters were shown to be degradable and could be prepared either from the pure polyester or from prefunctionalized polyesters, though the thiol-ene reactions were found to be less effective. Since then a new monomer, trans-2,5-dihydroxy-3-pentenoic acid methyl ester (DPM) has been...

Synthesis and Characterization of pH and Thermo Dual-Responsive Hydrogels with a Semi-IPN Structure Based on N-Isopropylacrylamide and Itaconamic Acid.

Science.gov (United States)

Rwei, Syang-Peng; Tuan, Huynh Nguyen Anh; Chiang, Whe-Yi; Way, Tun-Fun

2018-04-28

A series of semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized and investigated in this study. Linear copolymer poly( N -isopropylacrylamide-co-itaconamic acid) p(NIPAM-co-IAM), which is formed by copolymerization of N -isopropylacrylamide (NIPAM) and itaconamic acid (IAM, 4-amino-2-ethylene-4-oxobutanoic acid), was introduced into a solution of NIPAM to form a series of pH and thermo dual-responsive p(NIPAM-co-IAM)/pNIPAM semi-IPN hydrogels by free radical polymerization. The structural, morphological, chemical, and physical properties of the linear copolymer and semi-IPN hydrogels were investigated. The semi-IPN hydrogel showed high thermal stability according to thermal gravimetric analyzer (TGA). Scanning electronic microscopy (SEM) images showed that the pore size was in the range of 119~297 µm and could be controlled by the addition ratio of the linear copolymer in the semi-IPN structure. The addition of linear copolymer increased the fracture strain from 57.5 ± 2.9% to 91.1 ± 4.9% depending on the added amount, while the compressive modulus decreased as the addition increased. Moreover, the pH and thermo dual-responsive properties were investigated using differential scanning calorimetry (DSC) and monitoring the swelling behavior of the hydrogels. In deionized (DI) water, the equilibrium swelling ratio of the hydrogels decreased as the temperature increased from 20 °C to 50 °C, while it varied in various pH buffer solutions. In addition, the swelling and deswelling rates of the hydrogels also significantly increased. The results indicate that the novel pH-thermo dual-responsive semi-IPN hydrogels were synthesized successfully and may be a potential material for biomedical, drug delivery, or absorption application.

Lignin from hydrothermally pretreated grass biomass retards enzymatic cellulose degradation by acting as a physical barrier rather than by inducing nonproductive adsorption of enzymes

DEFF Research Database (Denmark)

Djajadi, Demi T.; Jensen, Mads M.; Oliveira, Marlene

2018-01-01

Lignin is known to hinder efficient enzymatic conversion of lignocellulose in biorefining processes. In particular, nonproductive adsorption of cellulases onto lignin is considered a key mechanism to explain how lignin retards enzymatic cellulose conversion in extended reactions. Lignin-rich resi...

Enzymatically Degradable Hybrid Organic-Inorganic Bridged Silsesquioxane Nanoparticles for In-Vitro Imaging

KAUST Repository

Fatieiev, Yevhen

2015-06-30

Non-aggregated dense bridged silsesquioxane (BS) nanoparticles based on nature-inspired oxamide bridges are shown to degrade in simulated biological media upon cleavage with endopeptidase. Fluorescent BS nanoprobes with incorporated fluorescein dyes were applied for in-vitro imaging in cancer cells.

2D parallel interpenetration of [M2(bpp)4X4] [M, Fe(II)/Co(II); bpp, 4,4'-trimethylenedipyridine; X, SCN-, SeCN- and N3-] complexes: Pseudohalide-dependent conformation of bpp

International Nuclear Information System (INIS)

Manna, Subal Chandra; Jana, Atish Dipankar; Rosair, Georgina M.; Drew, Michael G.B.; Mostafa, Golam; Ray Chaudhuri, Nirmalendu

2008-01-01

Three coordination complexes of Co(II)/Fe(II) with 4,4'-trimethylenedipyridine (bpp) and pseudohalides (SCN - , SeCN - and N 3 - ) have been synthesized. The complexes have been characterized by X-ray single crystal structure determination. They are isomorphous having 2D layers in which two independent wavy nets display parallel interwoven structures. Pseudohalide binds metal centers through N terminal and occupies the trans axial positions of the octahedral metal coordination environment. Pseudohalide remains pendant on both sides of the polymeric layer and help the stacking through hydrogen bonding. The conformation of bpp in the interpenetrated nets is observed to be dependent on the choice of pseudohalide. - Graphical abstract: Complexes of [M 2 (bpp) 4 X 4 ] [M, Fe(II)/Co(II); bpp, 4,4'-trimethylenedipyridine; X, SCN - , SeCN - and N3 - ] have been synthesized. The structural analysis reveals undulated 2D network with (4,4) net topology adopting two different conformations of bpp alternately. Two such networks undergo parallel interpenetration. Pseudohalides are observed to help in stacking the interpenetrated nets through hydrogen bonding

Automated assay for screening the enzymatic release of reducing sugars from micronized biomass

Directory of Open Access Journals (Sweden)

Asther Marcel

2010-07-01

Full Text Available Abstract Background To reduce the production cost of bioethanol obtained from fermentation of the sugars provided by degradation of lignocellulosic biomass (i.e., second generation bioethanol, it is necessary to screen for new enzymes endowed with more efficient biomass degrading properties. This demands the set-up of high-throughput screening methods. Several methods have been devised all using microplates in the industrial SBS format. Although this size reduction and standardization has greatly improved the screening process, the published methods comprise one or more manual steps that seriously decrease throughput. Therefore, we worked to devise a screening method devoid of any manual steps. Results We describe a fully automated assay for measuring the amount of reducing sugars released by biomass-degrading enzymes from wheat-straw and spruce. The method comprises two independent and automated steps. The first step is the making of "substrate plates". It consists of filling 96-well microplates with slurry suspensions of micronized substrate which are then stored frozen until use. The second step is an enzymatic activity assay. After thawing, the substrate plates are supplemented by the robot with cell-wall degrading enzymes where necessary, and the whole process from addition of enzymes to quantification of released sugars is autonomously performed by the robot. We describe how critical parameters (amount of substrate, amount of enzyme, incubation duration and temperature were selected to fit with our specific use. The ability of this automated small-scale assay to discriminate among different enzymatic activities was validated using a set of commercial enzymes. Conclusions Using an automatic microplate sealer solved three main problems generally encountered during the set-up of methods for measuring the sugar-releasing activity of plant cell wall-degrading enzymes: throughput, automation, and evaporation losses. In its present set-up, the

Nitrogen-doped graphene interpenetrated 3D Ni-nanocages: efficient and stable water-to-dioxygen electrocatalysts

Science.gov (United States)

Dhavale, Vishal M.; Gaikwad, Sachin S.; George, Leena; Devi, R. Nandini; Kurungot, Sreekumar

2014-10-01

Herein, we report the synthesis of a nitrogen-doped graphene (NGr) interpenetrated 3D Ni-nanocage (Ni-NGr) electrocatalyst by a simple water-in-oil (w/o) emulsion technique for oxidation of water to dioxygen. Correlation of adsorption of NGr and subsequent interpenetration through the specific surface plane of nickel particles as well as the concomitant interaction of N and C with Ni in the nano-regime has been investigated. Apart from the benefits of the synergistic interactions between Ni, N, and C, the overall integrity of the structure and its intra-molecular connectivity within the framework help in achieving better oxygen evolution characteristics at a significantly reduced overpotential. The engineered Ni-NGr nanocage displays a substantially low overpotential of ~290 mV at a practical current density of 20 mA cm-2 in 0.1 M KOH. In comparison, NGr and Ni-particles as separate entities give overpotentials of ~570 and ~370 mV under similar conditions. Moreover, the long term stability of Ni-NGr was investigated by anodic potential cycling for 500 cycles and an 8.5% increment in the overpotential at 20 mA cm-2 was observed. Additionally, a chronoamperometric test was performed for 15 h at 20 mA cm-2, which highlights the better sustainability of Ni-NGr under the actual operating conditions. Finally, the quantitative estimation of evolved oxygen was monitored by gas chromatography and was found to be 70 mmol h-1 g-1 of oxygen, which is constant in the second cycle as well.Herein, we report the synthesis of a nitrogen-doped graphene (NGr) interpenetrated 3D Ni-nanocage (Ni-NGr) electrocatalyst by a simple water-in-oil (w/o) emulsion technique for oxidation of water to dioxygen. Correlation of adsorption of NGr and subsequent interpenetration through the specific surface plane of nickel particles as well as the concomitant interaction of N and C with Ni in the nano-regime has been investigated. Apart from the benefits of the synergistic interactions between Ni, N

Differences in crystalline cellulose modification due to degradation by brown and white rot fungi.

Science.gov (United States)

Hastrup, Anne Christine Steenkjær; Howell, Caitlin; Larsen, Flemming Hofmann; Sathitsuksanoh, Noppadon; Goodell, Barry; Jellison, Jody

2012-10-01

Wood-decaying basidiomycetes are some of the most effective bioconverters of lignocellulose in nature, however the way they alter wood crystalline cellulose on a molecular level is still not well understood. To address this, we examined and compared changes in wood undergoing decay by two species of brown rot fungi, Gloeophyllum trabeum and Meruliporia incrassata, and two species of white rot fungi, Irpex lacteus and Pycnoporus sanguineus, using X-ray diffraction (XRD) and (13)C solid-state nuclear magnetic resonance (NMR) spectroscopy. The overall percent crystallinity in wood undergoing decay by M. incrassata, G. trabeum, and I. lacteus appeared to decrease according to the stage of decay, while in wood decayed by P. sanguineus the crystallinity was found to increase during some stages of degradation. This result is suggested to be potentially due to the different decay strategies employed by these fungi. The average spacing between the 200 cellulose crystal planes was significantly decreased in wood degraded by brown rot, whereas changes observed in wood degraded by the two white rot fungi examined varied according to the selectivity for lignin. The conclusions were supported by a quantitative analysis of the structural components in the wood before and during decay confirming the distinct differences observed for brown and white rot fungi. The results from this study were consistent with differences in degradation methods previously reported among fungal species, specifically more non-enzymatic degradation in brown rot versus more enzymatic degradation in white rot. Copyright © 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

[Influence of enzymatic hydrolyzate of mussel meat on growth and some indicators of general adaptation syndrome in rats].

Science.gov (United States)

Sidorova, Iu S; Seliaskin, K E; Zorin, S N; Abramova, L S; Mazo, V K

2014-01-01

The impact of the 15-day consumption of enzymatic hydrolyzate of the mussels meat as a part of semi-synthetic diet on some stress biomarkers and apoptosis activity in various organs of growing male Wistar rats have been studied. Enzymatic hydrolyzate of the mussels meat (EMM) was obtained in pilot conditions using the enzyme preparation "Protozim". The animals of control group 1 (n = 8 with initial body weight of 179.4 ± 5.9 g) and experimental group 2 (n = 8, 176.3 ± 4.5 g) received a semi synthetic diet; the animals of the experimental group 3 (n = 8, 177.6 ± 4.0 g) received the same semi synthetic diet in which 50% of the casein was replaced by the peptides of EMM. On the penult day of the experiment animals of groups 2 and 3 were subjected to stress exposure by electric current on their paws (current 0.4 mA for 8 seconds) and were placed in metabolic cages for the collection of daily urine. At the 15th day of the study, all control and test animals were killed by decapitation under ether anesthesia and necropsied. The content of prostaglandin E2 and β-endorphin in blood plasma was determined by ELISA test. The concentration of urine corticosterone was measured by HPLC. DNA damage and percentage of apoptotic cells (apoptotic index) were calculated in thymus by single-cell gel electrophoresis assay (Comet assay). The relative body weight increase of animals treated with EMM was significantly (p general adaptation syndrome.

Time delay effects on large-scale MR damper based semi-active control strategies

International Nuclear Information System (INIS)

Cha, Y-J; Agrawal, A K; Dyke, S J

2013-01-01

This paper presents a detailed investigation on the robustness of large-scale 200 kN MR damper based semi-active control strategies in the presence of time delays in the control system. Although the effects of time delay on stability and performance degradation of an actively controlled system have been investigated extensively by many researchers, degradation in the performance of semi-active systems due to time delay has yet to be investigated. Since semi-active systems are inherently stable, instability problems due to time delay are unlikely to arise. This paper investigates the effects of time delay on the performance of a building with a large-scale MR damper, using numerical simulations of near- and far-field earthquakes. The MR damper is considered to be controlled by four different semi-active control algorithms, namely (i) clipped-optimal control (COC), (ii) decentralized output feedback polynomial control (DOFPC), (iii) Lyapunov control, and (iv) simple-passive control (SPC). It is observed that all controllers except for the COC are significantly robust with respect to time delay. On the other hand, the clipped-optimal controller should be integrated with a compensator to improve the performance in the presence of time delay. (paper)

Kinetic modelling of enzymatic starch hydrolysis

NARCIS (Netherlands)

Bednarska, K.A.

2015-01-01

Kinetic modelling of enzymatic starch hydrolysis – a summary

K.A. Bednarska

The dissertation entitled ‘Kinetic modelling of enzymatic starch hydrolysis’ describes the enzymatic hydrolysis and kinetic modelling of liquefaction and saccharification of wheat starch.

The Paleozoic origin of enzymatic mechanisms for lignin degradation reconstructed using 31 fungal genomes

OpenAIRE

Floudas, Dimitrios; Binder, Manfred; Riley, Robert; Barry, Kerrie; Blanchette, Robert A; Henrissat, Bernard; Martinez, Angel T.; Otillar, Robert; Spatafora, Joseph W.; Yadav, Jagit S.; Aerts, Andrea; Benoit, Isabelle; Boyd, Alex; Carlson, Alexis; Copeland, Alex

2012-01-01

Wood is a major pool of organic carbon that is highly resistant to decay, owing largely to the presence of lignin. The only organisms capable of substantial lignin decay are white rot fungi in the Agaricomycetes, which also contains non?lignin-degrading brown rot and ectomycorrhizal species. Comparative analyses of 31 fungal genomes (12 generated for this study) suggest that lignin-degrading peroxidases expanded in the lineage leading to the ancestor of the Agaricomycetes, which is reconstruc...

Analysis of Enzymatic Activity of Matrix Metalloproteinase (MMP) by Collagen Zymography in Melanoma.

Science.gov (United States)

Walia, Vijay; Samuels, Yardena

2018-01-01

Protein zymography is the most commonly used technique to study the enzymatic activity of matrix metalloproteinases (MMPs) and their inhibitors. MMPs are proteolytic enzymes that promote extracellular matrix degradation. MMPs are frequently mutated in malignant melanomas as well as other cancers and are linked to increasing incidence of tumor metastasis. Substrate zymography characterizes MMP activity by their ability to degrade preferred substrates. Here we describe the collagen zymography technique to measure the active or latent form of MMPs using MMP-8 as an example, which is a frequently mutated MMP family member in malignant melanomas. The same technique can be used with the modification of substrate to detect metalloproteinase activity of other MMPs. Both wild-type and mutated forms of MMPs can be analyzed using a single gel using this method.

Structural optimization of interpenetrated pillared-layer coordination polymers for ethylene/ethane separation.

Science.gov (United States)

Kishida, Keisuke; Horike, Satoshi; Watanabe, Yoshihiro; Tahara, Mina; Inubushi, Yasutaka; Kitagawa, Susumu

2014-06-01

With the goal of achieving effective ethylene/ethane separation, we evaluated the gas sorption properties of four pillared-layer-type porous coordination polymers with double interpenetration, [Zn2(tp)2(bpy)]n (1), [Zn2(fm)2(bpe)]n (2), [Zn2(fm)2(bpa)]n (3), and [Zn2(fm)2(bpy)]n (4) (tp = terephthalate, bpy = 4,4'-bipyridyl, fm = fumarate, bpe = 1,2-di(4-pyridyl)ethylene and bpa = 1,2-di(4-pyridyl)ethane). It was found that 4, which contains the narrowest pores of all of these compounds, exhibited ethylene-selective sorption profiles. The ethylene selectivity of 4 was estimated to be 4.6 at 298 K based on breakthrough experiments using ethylene/ethane gas mixtures. In addition, 4 exhibited a good regeneration ability compared with a conventional porous material. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Degradation and removal of soybean allergen in Japanese soy sauce.

Science.gov (United States)

Magishi, Norihiro; Yuikawa, Naoya; Kobayashi, Makio; Taniuchi, Shoichiro

2017-08-01

Soy sauce is a traditional fermented seasoning of Japan and is available throughout the world. The two main raw ingredients of soy sauce are soybean and wheat, both of which are established food allergens. The present study examined the degradation and removal of soybean allergens in soy sauce by immunoblotting with anti‑soybean protein antibody from rabbit and sera from two children with soybean allergy. It was demonstrated that soybean allergens were gradually degraded during the fermentation process, but were not completely degraded in raw soy sauce. During the processes of heat‑treatment and filtration, the soluble soybean allergens in raw soy sauce were denatured to insoluble allergens by heat‑treatment and subsequently completely removed from soy sauce by filtration. Therefore, to reduce the allergenicity of soy sauce, heat‑treatment and filtration are very important processes in addition to the enzymatic degradation during the fermentation of soy sauce.

Interpenetrating polyaniline-gold electrodes for SERS and electrochemical measurements

Science.gov (United States)

West, R. M.; Semancik, S.

2016-11-01

Facile fabrication of nanostructured electrode arrays is critical for development of bimodal SERS and electrochemical biosensors. In this paper, the variation of applied potential at a polyaniline-coated Pt electrode is used to selectivity deposit Au on the polyaniline amine sites or on the underlying Pt electrode. By alternating the applied potential, the Au is grown simultaneously from the top and the bottom of the polyaniline film, leading to an interpenetrated, nanostructured polymer-metal composite extending from the Pt electrode to the electrolyte solution. The resulting films have unique pH-dependent electrochemical properties, e.g. they retain electrochemical activity in both acidic and neutral solutions, and they also include SERS-active nanostructures. By varying the concentration of chloroaurate used during deposition, Au nanoparticles, nanodendrites, or nanosheets can be selectively grown. For the films deposited under optimal conditions, using 5 mmol/L chloroaurate, the SERS enhancement factor for Rhodamine 6G was found to be as high as 1.1 × 106 with spot-to-spot and electrode-to-electrode relative standard deviations as low as 8% and 12%, respectively. The advantages of the reported PANI-Au composite electrodes lie in their facile fabrication, enabling the targeted deposition of tunable nanostructures on sensing arrays, and their ability to produce orthogonal optical and electrochemical analytical results.

Acylation Modification of Antheraea pernyi Silk Fibroin Using Succinic Anhydride and Its Effects on Enzymatic Degradation Behavior

Directory of Open Access Journals (Sweden)

Xiufang Li

2013-01-01

Full Text Available The degradation rate of tissue engineering scaffolds should match the regeneration rate of new tissues. Controlling the degradation behavior of silk fibroin is an important subject for silk-based tissue engineering scaffolds. In this study, Antheraea pernyi silk fibroin was successfully modified with succinic anhydride and then characterized by zeta potential, ninhydrin method, and FTIR. In vitro, three-dimensional scaffolds prepared with modified silk fibroin were incubated in collagenase IA solution for 18 days to evaluate the impact of acylation on the degradation behavior. The results demonstrated that the degradation rate of modified silk fibroin scaffolds was more rapid than unmodified ones. The content of the β-sheet structure in silk fibroin obviously decreased after acylation, resulting in a high degradation rate. Above all, the degradation behavior of silk fibroin scaffolds could be regulated by acylation to match the requirements of various tissues regeneration.

Aflatoxin B1 Degradation by a Pseudomonas Strain

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Lancine Sangare

2014-10-01

Full Text Available Aflatoxin B1 (AFB1, one of the most potent naturally occurring mutagens and carcinogens, causes significant threats to the food industry and animal production. In this study, 25 bacteria isolates were collected from grain kernels and soils displaying AFB1 reduction activity. Based on its degradation effectiveness, isolate N17-1 was selected for further characterization and identified as Pseudomonas aeruginosa. P. aeruginosa N17-1 could degrade AFB1, AFB2 and AFM1 by 82.8%, 46.8% and 31.9% after incubation in Nutrient Broth (NB medium at 37 °C for 72 h, respectively. The culture supernatant of isolate N17-1 degraded AFB1 effectively, whereas the viable cells and intra cell extracts were far less effective. Factors influencing AFB1 degradation by the culture supernatant were investigated. Maximum degradation was observed at 55 °C. Ions Mn2+ and Cu2+ were activators for AFB1 degradation, however, ions Mg2+, Li+, Zn2+, Se2+, Fe3+ were strong inhibitors. Treatments with proteinase K and proteinase K plus SDS significantly reduced the degradation activity of the culture supernatant. No degradation products were observed based on preliminary LC-QTOF/MS analysis, indicating AFB1 was metabolized to degradation products with chemical properties different from that of AFB1. The results indicated that the degradation of AFB1 by P. aeruginosa N17-1 was enzymatic and could have a great potential in industrial applications. This is the first report indicating that the isolate of P. aeruginosa possesses the ability to degrade aflatoxin.

Degradability of polylactide films by commercial microbiological preparations for household composters

Directory of Open Access Journals (Sweden)

Morawska Magda

2017-09-01

Full Text Available Environmentally friendly polymers such as polylactide are increasingly becoming available for use in packaging applications. The main advantages of polylactide packaging are evident. Polylactide is based on renewable resources and can be degraded in compost or soil. The studies on degradability of polylactide (PLA films by commercial preparation of mixture of multi-active saprophytic soil microorganisms, bacteria, actinomycetes and fungi have been done. Unmodified PLA film, metalized co-extruded PLA film and modified by silicon oxide PLA film were incubated in the liquid nutritious medium (TSB prepared to support the growth of microorganisms. The degradability of polylactide films was examined by macro and microscopic observations of surface, changes of mass and crystallinity of polymer samples before and after incubation. The obtained results indicate that the degradation of polylactide was accelerated by the presence of a biological vaccine. It was found that PLA degradation in the inoculated TSB broth was a result of both: enzymatic and chemical hydrolysis.

Degradation of chitosan for rice crops application

International Nuclear Information System (INIS)

Norzita Yacob; Maznah Mahmud; Norhashidah Talip; Kamaruddin Hashim; Abdul Rahim Harun; Khairul Zaman; Hj Dahlan

2013-01-01

A variety of techniques including chemical and enzymatic hydrolysis, and radiation degradation processes can be used to prepare low molecular weight chitosan. Degradation of chitosan by radiation can be carried out in solid state and liquid state. Radiation degraded polysaccharides has been reported to exhibit growth-stimulating activity like phytohormones that induce the promotion in germination, shoot and root elongation in variety of plants. In this study, the chitosan was irradiated in solid state (powder form) by gamma rays within the dose range of 25-75 kGy. And the irradiated chitosan was then irradiated in solution form in the presence of hydrogen peroxide. The effects of irradiation on the molecular weight and viscosity of the chitosan were investigated using Ubbelohde Capillary Viscometer. The molecular weight and viscosity of the chitosan decreased with increment of absorbed doses. In the presence of hydrogen peroxide, the molecular weight of chitosan could be further decreased. The effect of radiation degraded chitosan on the growth promotion of rice was investigated and it was shown during seedling period of 15 days for transplanting whereby the growth is 15%-20% faster than using chemicals growth promoters. (authors)

Synthesis and characterization of p and n dopable interpenetrating polymer networks for organic photovoltaic devices

International Nuclear Information System (INIS)

Lav, T.X.; Tran-Van, F.; Vidal, F.; Peralta, S.; Chevrot, C.; Teyssie, D.; Grazulevicius, J.V.; Getautis, V.; Derbal, H.; Nunzi, J.-M.

2008-01-01

Interpenetrating polymer networks (IPN) based on carbazole derivatives and diacrylate perylene are synthesized in two steps via an in-situ process. From a spin-coated thin film of a mixture of the two precursors, the diacrylate perylene is first photopolymerized to form a network in the presence of the carbazole derivative which is then electropolymerized to elaborate the IPN. Electrochemical characterizations show that the carbazole and perylene are electroactive inside the film which confirm the p and n dopable properties of the IPN. AFM images of the IPNs show a homogenous and smooth surface, compared to single network, which indicate a high quality of association of each network which should allow an efficient p/n bulk heterojunction

Synthesis and characterization of p and n dopable interpenetrating polymer networks for organic photovoltaic devices

Energy Technology Data Exchange (ETDEWEB)

Lav, T.X. [Laboratoire de Physicochimie des Polymeres et des Interfaces, EA 2528 Universite de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise Cedex (France); Tran-Van, F. [Laboratoire de Physicochimie des Polymeres et des Interfaces, EA 2528 Universite de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise Cedex (France)], E-mail: francois.tran-van@u-cergy.fr; Vidal, F.; Peralta, S.; Chevrot, C.; Teyssie, D. [Laboratoire de Physicochimie des Polymeres et des Interfaces, EA 2528 Universite de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise Cedex (France); Grazulevicius, J.V.; Getautis, V. [Faculty of Chemical Technology, Kaunas University of Technology, Radvilenu Plentas 19, LT 50254 (Lithuania); Derbal, H.; Nunzi, J.-M. [PPF Cellules Solaires Photovoltaiques Plastiques - Laboratoire POMA, UMR-CNRS 6136, Universite d' Angers, 2 bd Lavoisier, 49045 Angers (France)

2008-08-30

Interpenetrating polymer networks (IPN) based on carbazole derivatives and diacrylate perylene are synthesized in two steps via an in-situ process. From a spin-coated thin film of a mixture of the two precursors, the diacrylate perylene is first photopolymerized to form a network in the presence of the carbazole derivative which is then electropolymerized to elaborate the IPN. Electrochemical characterizations show that the carbazole and perylene are electroactive inside the film which confirm the p and n dopable properties of the IPN. AFM images of the IPNs show a homogenous and smooth surface, compared to single network, which indicate a high quality of association of each network which should allow an efficient p/n bulk heterojunction.

Mathematical and numerical analysis of a multi-velocity multi-fluid model for interpenetration of miscible fluids

International Nuclear Information System (INIS)

Enaux, C.

2007-11-01

The simulation of indirect laser implosion requires an accurate knowledge of the inter-penetration of the laser target materials turned into plasma. This work is devoted to the study of a multi-velocity multi-fluid model recently proposed by Scannapieco and Cheng (SC) to describe the inter-penetration of miscible fluids. In this document, we begin with presenting the SC model in the context of miscible fluids flow modelling. Afterwards, the mathematical analysis of the model is carried out (study of the hyperbolicity, existence of a strictly convex mathematical entropy, asymptotic analysis and diffusion limit). As a conclusion the problem is well set. Then, we focus on the problem of numerical resolution of systems of conservation laws with a relaxation source term, because SC model belongs to this class. The main difficulty of this task is to capture on a coarse grid the asymptotic behaviour of the system when the source term is stiff. The main contribution of this work lies in the proposition of a new technique, allowing us to construct a Lagrangian numerical flux taking into account the presence of the source term. This technique is applied first on the model-problem of a one-dimensional Euler system with friction, and then on the multi-fluid SC model. In both cases, we prove that the new scheme is asymptotic-preserving and entropic under a CFL-like condition. The two-dimensional extension of the scheme is done by using a standard alternate directions method. Some numerical results highlight the contribution of the new flux, compared with a standard Lagrange plus Remap scheme where the source term is processed using an operator splitting. (author)

Mechanical study of PLA-PCL fibers during in vitro degradation

OpenAIRE

Vieira, AC; Vieira, JC; Ferra, JM; Magalhaes, FD; Guedes, RM; Marques, AT

2011-01-01

The aliphatic polyesters are widely used in biomedical applications since they are susceptible to hydrolytic and/or enzymatic chain cleavage, leading to alpha-hydroxyacids, generally metabolized in the human body. This is particularly useful for many biomedical applications, especially, for temporary mechanical supports in regenerative medical devices. Ideally, the degradation should be compatible with the tissue recovering. In this work, the evolution of mechanical properties during degradat...

Interpenetrated Binary Supramolecular Nanofibers for Sensitive Fluorescence Detection of Six Classes of Explosives.

Science.gov (United States)

Xiong, Wei; Zhu, Qijian; Gong, Yanjun; Wang, Chen; Che, Yanke; Zhao, Jincai

2018-04-03

In this work, we develop a sequential self-assembly approach to fabricate interpenetrated binary supramolecular nanofibers consisting of carbazole oligomer 1-cobalt(II) (1-Co 2+ ) coordination nanofibers and oligomer 2 nanofibers for the sensitive detection of six classes of explosives. When exposed to peroxide explosives (e.g., H 2 O 2 ), Co 2+ in 1-Co 2+ coordination nanofibers can be reduced to Co + that can transfer an electron to the excited 2 nanofibers and thereby quench their fluorescence. On the other hand, when exposed to the other five classes of explosives, the excited 2 nanofibers can transfer an electron to explosives to quench their fluorescence. On the basis of the distinct fluorescence quenching mechanisms, six classes of explosives can be sensitively detected. Herein, we provide a new strategy to design broad-band fluorescence sensors for a rich identification of threats.

Vitamin C degradation products and pathways in the human lens.

Science.gov (United States)

Nemet, Ina; Monnier, Vincent M

2011-10-28

Vitamin C and its degradation products participate in chemical modifications of proteins in vivo through non-enzymatic glycation (Maillard reaction) and formation of different products called advanced glycation end products. Vitamin C levels are particularly high in selected tissues, such as lens, brain and adrenal gland, and its degradation products can inflict substantial protein damage via formation of advanced glycation end products. However, the pathways of in vivo vitamin C degradation are poorly understood. Here we have determined the levels of vitamin C oxidation and degradation products dehydroascorbic acid, 2,3-diketogulonic acid, 3-deoxythreosone, xylosone, and threosone in the human lens using o-phenylenediamine to trap both free and protein-bound adducts. In the protein-free fraction and water-soluble proteins (WSP), all five listed degradation products were identified. Dehydroascorbic acid, 2,3-diketogulonic acid, and 3-deoxythreosone were the major products in the protein-free fraction, whereas in the WSP, 3-deoxythreosone was the most abundant measured dicarbonyl. In addition, 3-deoxythreosone in WSP showed positive linear correlation with age (p degradation product bound to human lens proteins provides in vivo evidence for the non-oxidative pathway of dehydroascorbate degradation into erythrulose as a major pathway for vitamin C degradation in vivo.

Highly water-absorbing silk yarn with interpenetrating network via in situ polymerization.

Science.gov (United States)

Lee, Ka I; Wang, Xiaowen; Guo, Xia; Yung, Ka-Fu; Fei, Bin

2017-02-01

Silk was modified via in situ polymerization of two monomers acrylamide and sodium acrylate by swelling in an effective LiBr dissolution system. Swelling of natural silks in LiBr solutions of low concentration was clearly observed under optical microscope, and their conformational changes were revealed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Dissolution tests and FTIR spectra of these modified silks suggested the presence of interpenetrating network of polyacrylamide and poly(sodium acrylate) in the silk yarns. These modified silks exhibited superior water absorption to that of raw silk and greatly improved mechanical properties in both dry and wet states. These novel modified silks also showed low cytotoxicity towards skin keratinocytes, having potential applications in biomedical textiles. This modification method by in situ polymerization after swelling in LiBr provides a new route to highly enhance the properties and performance of silk for various applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Kinetic instability of electrostatic ion cyclotron waves in inter-penetrating plasmas

Science.gov (United States)

Bashir, M. F.; Ilie, R.; Murtaza, G.

2018-05-01

The Electrostatic Ion Cyclotron (EIC) instability that includes the effect of wave-particle interaction is studied owing to the free energy source through the flowing velocity of the inter-penetrating plasmas. It is shown that the origin of this current-less instability is different from the classical current driven EIC instability. The threshold conditions applicable to a wide range of plasma parameters and the estimate of the growth rate are determined as a function of the normalized flowing velocity ( u0/vt f e ), the temperature ( Tf/Ts ) and the density ratios ( nf 0/ns 0 ) of flowing component to static one. The EIC instability is driven by either flowing electrons or flowing ions, depending upon the different Doppler shifted frequency domains. It is found that the growth rate for electron-driven instability is higher than the ion-driven one. However, in both cases, the denser (hotter) is the flowing plasma, the lesser (greater) is the growth rate. The possible applications related to the terrestrial solar plasma environment are also discussed.

Enzymatic activity of the cellulolytic complex produced by trichoderma reesei. Enzymatic hydrolysis of cellulose

International Nuclear Information System (INIS)

Alfonsel Jaen, M.; Negro, M.J.; Saez, R.; Martin Moreno, C.

1986-01-01

The enzymatic activity characterization of the cellulolytic complex obtained from Trichoderma reese QM 9414 and the influence of the enzymatic hydrolysis conditions on the hydrolysis yield are studied. Pure cellulose and native or alkali pretreated biomass from Onopordum nervosum have been used as substrates. The values of pH, temperature, substrate concentration and enzyme-substrate ratio for the optimum activity of that complex, evaluated as glucose and reducing sugars productions, have been selected. Previous studies on enzymatic hydrolysis of O. nervosum have shown a remarkable effect of the alkaline pretreatments on the final hydrolysis yield. (author). 10 figs.; 10 refs

Enzymatic activity of the cellulolytic complex produced by Trichoderma reesei. Enzymatic hydrolysis of cellulose

International Nuclear Information System (INIS)

Alfonsel J, M.; Negro A, M. J.; Saez A, R.; Martin M, C.

1986-01-01

The enzymatic activity characterization of the cellulolytic complex obtained from Trichoderma reesei QM 9414 and the influence of the enzymatic hydrolysis conditions on the hydrolysis yield are studied. Pure cellulose and native or alkali pretreated biomass Onopordum nervosum have been used as substrates. The values of pH, temperature, substrate concentration and enzyme-substrate ratio for the optimum activity of that complex, evaluated as glucose and reducing sugars production, have been selected. Previous studies on enzymatic hydrolysis of 0. nervosum have shown a remarkable effect of the alkaline pretreatments on the final hydrolysis yield. (Author) 10 refs

A bacterium that degrades and assimilates poly(ethylene terephthalate).

Science.gov (United States)

Yoshida, Shosuke; Hiraga, Kazumi; Takehana, Toshihiko; Taniguchi, Ikuo; Yamaji, Hironao; Maeda, Yasuhito; Toyohara, Kiyotsuna; Miyamoto, Kenji; Kimura, Yoshiharu; Oda, Kohei

2016-03-11

Poly(ethylene terephthalate) (PET) is used extensively worldwide in plastic products, and its accumulation in the environment has become a global concern. Because the ability to enzymatically degrade PET has been thought to be limited to a few fungal species, biodegradation is not yet a viable remediation or recycling strategy. By screening natural microbial communities exposed to PET in the environment, we isolated a novel bacterium, Ideonella sakaiensis 201-F6, that is able to use PET as its major energy and carbon source. When grown on PET, this strain produces two enzymes capable of hydrolyzing PET and the reaction intermediate, mono(2-hydroxyethyl) terephthalic acid. Both enzymes are required to enzymatically convert PET efficiently into its two environmentally benign monomers, terephthalic acid and ethylene glycol. Copyright © 2016, American Association for the Advancement of Science.

Potential Signatures of Semi-volatile Compounds Associated With Nuclear Processing

Energy Technology Data Exchange (ETDEWEB)

Probasco, Kathleen M.; Birnbaum, Jerome C.; Maughan, A. D.

2002-06-01

Semi-volatile chemicals associated with nuclear processes (e.g., the reprocessing of uranium to produce plutonium for nuclear weapons, or the separation of actinides from processing waste streams), can provide sticky residues or signatures that will attach to piping, ducting, soil, water, or other surface media. Volatile compounds, that are more suitable for electro-optical sensing, have been well studied. However, the semi-volatile compounds have not been well documented or studied. A majority of these semi-volatile chemicals are more robust than typical gaseous or liquid chemicals and can have lifetimes of several weeks, months, or years in the environment. However, large data gaps exist concerning these potential signature compounds and more research is needed to fill these data gaps so that important signature information is not overlooked or discarded. This report investigates key semi-volatile compounds associated with nuclear separations, identifies available chemical and physical properties, and discusses the degradation products that would result from hydrolysis, radiolysis and oxidation reactions on these compounds.

Low melting point pyridinium ionic liquid pretreatment for enhancing enzymatic saccharification of cellulosic biomass.

Science.gov (United States)

Uju; Nakamoto, Aya; Shoda, Yasuhiro; Goto, Masahiro; Tokuhara, Wataru; Noritake, Yoshiyuki; Katahira, Satoshi; Ishida, Nobuhiro; Ogino, Chiaki; Kamiya, Noriho

2013-05-01

The potential of 1-hexylpyridinium chloride ([Hpy][Cl]), to pretreat cellulosic feedstocks was investigated using microcrystalline cellulose (Avicel) and Bagasse at 80 °C or 100 °C. Short [Hpy][Cl] pretreatments, conversion of pretreated Avicel to glucose was attained after 24h enzymatic saccharification under optimal conditions, whereas regenerated Bagasse showed 1-3-fold higher conversion than untreated biomass. FT-IR analysis of both Avicel and Bagasse samples pretreated with [Hpy][Cl] or 1-ethyl-3-methyimidazolium acetate ([Emim][OAc]) revealed that these ionic liquids behaved differently during pretreatment. [Hpy][Cl] pretreatment for an extended duration (180 min) released mono- and disaccharides without using cellulase enzymes, suggesting [Hpy][Cl] has capability for direct saccharification of cellulosic feedstocks. On the basis of the results obtained, [Hpy][Cl] pretreatment enhanced initial reaction rates in enzymatic saccharification by either crystalline polymorphic alteration of cellulose or partial degradation of the crystalline cellulosic fraction in biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.

Degradation of orange dyes and carbamazepine by soybean peroxidase immobilized on silica monoliths and titanium dioxide.

Science.gov (United States)

Calza, Paola; Zacchigna, Dario; Laurenti, Enzo

2016-12-01

In this paper, the removal of three common dyes (orange I, orange II, and methylorange) and of the anticonvulsant drug carbamazepine from aqueous solutions by means of enzymatic and photocatalytic treatment was studied. Soybean peroxidase (SBP) was used as biocatalyst, both free in solution and immobilized on silica monoliths, and titanium dioxide as photocatalyst. The combination of the two catalysts led to a faster (about two to four times) removal of all the orange dyes compared to the single systems. All the dyes were completely removed within 2 h, also in the presence of immobilized SBP. As for carbamazepine, photocatalytic treatment prevails on the enzymatic degradation, but the synergistic effect of two catalysts led to a more efficient degradation; carbamazepine's complete disappearance was achieved within 60 min with combined system, while up to 2 h is required with TiO 2 only.

Enhancing bioactive peptide release and identification using targeted enzymatic hydrolysis of milk proteins.

Science.gov (United States)

Nongonierma, Alice B; FitzGerald, Richard J

2018-06-01

Milk proteins have been extensively studied for their ability to yield a range of bioactive peptides following enzymatic hydrolysis/digestion. However, many hurdles still exist regarding the widespread utilization of milk protein-derived bioactive peptides as health enhancing agents for humans. These mostly arise from the fact that most milk protein-derived bioactive peptides are not highly potent. In addition, they may be degraded during gastrointestinal digestion and/or have a low intestinal permeability. The targeted release of bioactive peptides during the enzymatic hydrolysis of milk proteins may allow the generation of particularly potent bioactive hydrolysates and peptides. Therefore, the development of milk protein hydrolysates capable of improving human health requires, in the first instance, optimized targeted release of specific bioactive peptides. The targeted hydrolysis of milk proteins has been aided by a range of in silico tools. These include peptide cutters and predictive modeling linking bioactivity to peptide structure [i.e., molecular docking, quantitative structure activity relationship (QSAR)], or hydrolysis parameters [design of experiments (DOE)]. Different targeted enzymatic release strategies employed during the generation of milk protein hydrolysates are reviewed herein and their limitations are outlined. In addition, specific examples are provided to demonstrate how in silico tools may help in the identification and discovery of potent milk protein-derived peptides. It is anticipated that the development of novel strategies employing a range of in silico tools may help in the generation of milk protein hydrolysates containing potent and bioavailable peptides, which in turn may be used to validate their health promoting effects in humans. Graphical abstract The targeted enzymatic hydrolysis of milk proteins may allow the generation of highly potent and bioavailable bioactive peptides.

Oxidative degradation of alkylphenols by horseradish peroxidase.

Science.gov (United States)

Sakuyama, Hisae; Endo, Yasushi; Fujimoto, Kenshiro; Hatana, Yasuhiko

2003-01-01

Alkylphenols such as bisphenol A (2,2-bis(4-hydroxyphenyl)propane; BPA), p-nonylphenol (p-NP), and p-octylphenol (p-OP) that are known as endocrine disrupters were oxidized by horseradish (Armoracia rusticana) peroxidase (HRP) with H2O2. The optimal pHs for BPA, p-NP, and p-OP were 8.0, 7.0, and 5.0, respectively. The optimal temperature for BPA was 20 degrees C. Although BPA was rapidly degraded by HRP, its degradation depended on the concentration of HRP. Most of the oxidation products of BPA were polymers, although some 4-isopropenylphenol was produced. When male Japanese medaka (Oryzias latipes) were exposed to BPA, vitellogenin in the blood increased. However, no increased vitellogenin was observed in medaka exposed to HRP-oxidized BPA. The enzymatic oxidation of BPA using HRP was able to eliminate its estrogen-like activity.

Several genes encoding enzymes with the same activity are necessary for aerobic fungal degradation of cellulose in nature.

Directory of Open Access Journals (Sweden)

Peter K Busk

Full Text Available The cellulose-degrading fungal enzymes are glycoside hydrolases of the GH families and lytic polysaccharide monooxygenases. The entanglement of glycoside hydrolase families and functions makes it difficult to predict the enzymatic activity of glycoside hydrolases based on their sequence. In the present study we further developed the method Peptide Pattern Recognition to an automatic approach not only to find all genes encoding glycoside hydrolases and lytic polysaccharide monooxygenases in fungal genomes but also to predict the function of the genes. The functional annotation is an important feature as it provides a direct route to predict function from primary sequence. Furthermore, we used Peptide Pattern Recognition to compare the cellulose-degrading enzyme activities encoded by 39 fungal genomes. The results indicated that cellobiohydrolases and AA9 lytic polysaccharide monooxygenases are hallmarks of cellulose-degrading fungi except brown rot fungi. Furthermore, a high number of AA9, endocellulase and β-glucosidase genes were identified, not in what are known to be the strongest, specialized lignocellulose degraders but in saprophytic fungi that can use a wide variety of substrates whereas only few of these genes were found in fungi that have a limited number of natural, lignocellulotic substrates. This correlation suggests that enzymes with different properties are necessary for degradation of cellulose in different complex substrates. Interestingly, clustering of the fungi based on their predicted enzymes indicated that Ascomycota and Basidiomycota use the same enzymatic activities to degrade plant cell walls.

Production of heterologous cutinases by E. coli and improved enzyme formulation for application on plastic degradation

OpenAIRE

Gomes,Daniela S; Matamá,Teresa; Cavaco-Paulo,Artur; Campos-Takaki,Galba M; Salgueiro,Alexandra A

2013-01-01

Background: The hydrolytic action of cutinases has been applied to the degradation of plastics. Polyethylene terephthalate (PET) have long half-life which constitutes a major problem for their treatment as urban solid residues. The aim of this work was to characterize and to improve stable the enzyme to optimize the process of degradation using enzymatic hydrolysis of PET by recombinant cutinases. Results: The wild type form of cutinase from Fusarium solani pisi and its C-terminal fusion to c...

Tailoring conservation agriculture technologies to West Africa semi-arid zones: Building on traditional local practices for soil restoration

NARCIS (Netherlands)

Lahmar, R.; Bationo, B.A.; Lamso, N.D.; Guéro, Y.; Tittonell, P.A.

2012-01-01

Low inherent fertility of tropical soils and degradation, nutrient deficiency and water stress are the key factors that hamper rainfed agriculture in semi-arid West Africa. Conservation Agriculture (CA) is currently promoted in the region as a technology to reduce soil degradation, mitigate the

Evaluation of mechano-chemical degradation induced stresses of polyolefin pipes

Energy Technology Data Exchange (ETDEWEB)

Choi, Byoung Ho [Korea Univ., Seoul (Korea, Republic of); Chudnovsky, Alexander [The University of Illinois, Chicago (United States)

2008-07-01

The fracture phenomena in engineering thermoplastics resulting from chemical degradation is usually observed in the form of a microcrack network within a surface layer of degraded polymer exposed to a combined action of mechanical stresses and chemically aggressive environment. Degradation of polymers is usually manifested in a reduction of molecular weight, increase of crystallinity in semi crystalline polymers, increase of material density, a subtle increase in yield strength, and a dramatic reduction in toughness. The critical level of degradation for fracture initiation depends on the rates of toughness deterioration and build-up of the degradation related stresses as well as on the manufacturing and service stresses. In this paper, the evaluation of mechano-chemical degradation induced stress is attempted, and the application of the evaluated stress to the fracture initiation of polymer pipes is presented.

Evaluation of mechano-chemical degradation induced stresses of polyolefin pipes

International Nuclear Information System (INIS)

Choi, Byoung Ho; Chudnovsky, Alexander

2008-01-01

The fracture phenomena in engineering thermoplastics resulting from chemical degradation is usually observed in the form of a microcrack network within a surface layer of degraded polymer exposed to a combined action of mechanical stresses and chemically aggressive environment. Degradation of polymers is usually manifested in a reduction of molecular weight, increase of crystallinity in semi crystalline polymers, increase of material density, a subtle increase in yield strength, and a dramatic reduction in toughness. The critical level of degradation for fracture initiation depends on the rates of toughness deterioration and build-up of the degradation related stresses as well as on the manufacturing and service stresses. In this paper, the evaluation of mechano-chemical degradation induced stress is attempted, and the application of the evaluated stress to the fracture initiation of polymer pipes is presented

Degradation of Akt using protein-catalyzed capture agents.

Science.gov (United States)

Henning, Ryan K; Varghese, Joseph O; Das, Samir; Nag, Arundhati; Tang, Grace; Tang, Kevin; Sutherland, Alexander M; Heath, James R

2016-04-01

Abnormal signaling of the protein kinase Akt has been shown to contribute to human diseases such as diabetes and cancer, but Akt has proven to be a challenging target for drugging. Using iterative in situ click chemistry, we recently developed multiple protein-catalyzed capture (PCC) agents that allosterically modulate Akt enzymatic activity in a protein-based assay. Here, we utilize similar PCCs to exploit endogenous protein degradation pathways. We use the modularity of the anti-Akt PCCs to prepare proteolysis targeting chimeric molecules that are shown to promote the rapid degradation of Akt in live cancer cells. These novel proteolysis targeting chimeric molecules demonstrate that the epitope targeting selectivity of PCCs can be coupled with non-traditional drugging moieties to inhibit challenging targets. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

In vitro degradation behaviour of biodegradable soy plastics : effects of crosslinking with glyoxal and thermal treatment

NARCIS (Netherlands)

Vaz, C.M.; Graaf, de L.A.; Reis, R.L.; Cunha, A.M.

2003-01-01

In-vitro degradation of soy-derived protein materials, non-crosslinked (SItp), crosslinked with glyoxal (X-SItp) or submitted to heat treatment (24TT-SItp), was studied with either an isotonic saline solution without enzymatic activity or containing bacterial collagenase. The changes in weight of

Comparison of the role that entropy has played in processes of non-enzymatic and enzymatic catalysis

International Nuclear Information System (INIS)

Dixon Pineda, Manuel Tomas

2012-01-01

The function that entropy has played is compared in processes of non-enzymatic and enzymatic catalysis. The processes followed are showed: the kinetics of the acid hydrolysis of 3-pentyl acetate and cyclopentyl acetate catalyzed by hydrochloric acid and enzymatic hydrolysis of ethyl acetate and γ-butyrolactone catalyzed by pig liver esterase. The activation parameters of Eyring were determined for each process and interpreted the contribution of the entropy of activation for catalysis in this type of model reactions. (author) [es

ERManI (Endoplasmic Reticulum Class I α-Mannosidase) Is Required for HIV-1 Envelope Glycoprotein Degradation via Endoplasmic Reticulum-associated Protein Degradation Pathway.

Science.gov (United States)

Zhou, Tao; Frabutt, Dylan A; Moremen, Kelley W; Zheng, Yong-Hui

2015-09-04

Previously, we reported that the mitochondrial translocator protein (TSPO) induces HIV-1 envelope (Env) degradation via the endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway, but the mechanism was not clear. Here we investigated how the four ER-associated glycoside hydrolase family 47 (GH47) α-mannosidases, ERManI, and ER-degradation enhancing α-mannosidase-like (EDEM) proteins 1, 2, and 3, are involved in the Env degradation process. Ectopic expression of these four α-mannosidases uncovers that only ERManI inhibits HIV-1 Env expression in a dose-dependent manner. In addition, genetic knock-out of the ERManI gene MAN1B1 using CRISPR/Cas9 technology disrupts the TSPO-mediated Env degradation. Biochemical studies show that HIV-1 Env interacts with ERManI, and between the ERManI cytoplasmic, transmembrane, lumenal stem, and lumenal catalytic domains, the catalytic domain plays a critical role in the Env-ERManI interaction. In addition, functional studies show that inactivation of the catalytic sites by site-directed mutagenesis disrupts the ERManI activity. These studies identify ERManI as a critical GH47 α-mannosidase in the ER-associated protein degradation pathway that initiates the Env degradation and suggests that its catalytic domain and enzymatic activity play an important role in this process. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Improvement of Soybean Oil Solvent Extraction through Enzymatic Pretreatment

Directory of Open Access Journals (Sweden)

F. V. Grasso

2012-01-01

Full Text Available The purpose of this study is to evaluate multienzyme hydrolysis as a pretreatment option to improve soybean oil solvent extraction and its eventual adaptation to conventional processes. Enzymatic action causes the degradation of the cell structures that contain oil. Improvements in terms of extraction, yield, and extraction rate are expected to be achieved. Soybean flakes and collets were used as materials and hexane was used as a solvent. Temperature, pH, and incubation time were optimized and diffusion coefficients were estimated for each solid. Extractions were carried out in a column, oil content was determined according to time, and a mathematical model was developed to describe the system. The optimum conditions obtained were pH 5.4, 38°C, and 9.7 h, and pH 5.8, 44°C, and 5.8h of treatment for flakes and collets, respectively. Hydrolyzed solids exhibited a higher yield. Diffusion coefficients were estimated between 10-11 and 10-10. The highest diffusion coefficient was obtained for hydrolyzed collets. 0.73 g oil/mL and 0.7 g oil/mL were obtained at 240 s in a column for collets and flakes, respectively. Hydrolyzed solids exhibited a higher yield. The enzymatic incubation accelerates the extraction rate and allows for higher yield. The proposed model proved to be appropriate.

Enzymatic oxidative biodegradation of nanoparticles: Mechanisms, significance and applications

Energy Technology Data Exchange (ETDEWEB)

Vlasova, Irina I. [Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219 (United States); Research Institute for Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow 119453 (Russian Federation); Kapralov, Alexandr A. [Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219 (United States); Michael, Zachary P.; Burkert, Seth C. [Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Shurin, Michael R. [Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA 15261 (United States); Department of Immunology, University of Pittsburgh Medical Center, Pittsburgh, PA 15261 (United States); Star, Alexander [Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Shvedova, Anna A., E-mail: ats@cdc.gov [Pathology and Physiology Research Branch, Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH) and Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26505 (United States); Kagan, Valerian E., E-mail: kagan@pitt.edu [Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219 (United States); Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Departments of Pharmacology and Chemical Biology and Radiation Oncology, University of Pittsburgh, Pittsburgh, PA 15260 (United States)

2016-05-15

Biopersistence of carbon nanotubes, graphene oxide (GO) and several other types of carbonaceous nanomaterials is an essential determinant of their health effects. Successful biodegradation is one of the major factors defining the life span and biological responses to nanoparticles. Here, we review the role and contribution of different oxidative enzymes of inflammatory cells – myeloperoxidase, eosinophil peroxidase, lactoperoxidase, hemoglobin, and xanthine oxidase – to the reactions of nanoparticle biodegradation. We further focus on interactions of nanomaterials with hemoproteins dependent on the specific features of their physico-chemical and structural characteristics. Mechanistically, we highlight the significance of immobilized peroxidase reactive intermediates vs diffusible small molecule oxidants (hypochlorous and hypobromous acids) for the overall oxidative biodegradation process in neutrophils and eosinophils. We also accentuate the importance of peroxynitrite-driven pathways realized in macrophages via the engagement of NADPH oxidase- and NO synthase-triggered oxidative mechanisms. We consider possible involvement of oxidative machinery of other professional phagocytes such as microglial cells, myeloid-derived suppressor cells, in the context of biodegradation relevant to targeted drug delivery. We evaluate the importance of genetic factors and their manipulations for the enzymatic biodegradation in vivo. Finally, we emphasize a novel type of biodegradation realized via the activation of the “dormant” peroxidase activity of hemoproteins by the nano-surface. This is exemplified by the binding of GO to cyt c causing the unfolding and ‘unmasking’ of the peroxidase activity of the latter. We conclude with the strategies leading to safe by design carbonaceous nanoparticles with optimized characteristics for mechanism-based targeted delivery and regulatable life-span of drugs in circulation. - Highlights: • Nanoparticles can be degraded by

Thermal and enzymatic pretreatment of sludge containing phthalate esters prior to mesophilic anaerobic digestion

DEFF Research Database (Denmark)

Gavala, Hariklia N.; Yenal, U.; Ahring, Birgitte Kiær

2004-01-01

The present study aimed at investigating the effect of thermal pretreatment of sludge at 70degreesC on the anaerobic degradation of three commonly found phthalic acid esters (PAE): di-ethyl phthalate (DEP), di-butyl phthalate (DBP), and di-ethylhexyl phthalate (DEHP). Also, the enzymatic treatment...... at 28degreesC with a commercial lipase was studied as a way to enhance PAE removal. Pretreatment at 70degreesC of the sludge containing PAE negatively influenced the anaerobic biodegradability of phthalate esters at 37degreesC. The observed reduction of PAE biodegradation rates after the thermal...... pretreatment was found to be proportional to the PAE solubility in water: the higher the solubility, the higher the percentage of the reduction (DEP > DBP > DEHP). PAE were slowly degraded during the pretreatment at 70degreesC, yet this was probably due to physicochemical reactions than to microbial...

Mechano-Enzymatic Deconstruction with a New Enzymatic Cocktail to Enhance Enzymatic Hydrolysis and Bioethanol Fermentation of Two Macroalgae Species

Directory of Open Access Journals (Sweden)

Sameh Amamou

2018-01-01

Full Text Available The aim of this study was to explore the efficiency of a mechano-enzymatic deconstruction of two macroalgae species for sugars and bioethanol production, by using a new enzymatic cocktail (Haliatase and two types of milling modes (vibro-ball: VBM and centrifugal milling: CM. By increasing the enzymatic concentration from 3.4 to 30 g/L, the total sugars released after 72 h of hydrolysis increased (from 6.7 to 13.1 g/100 g TS and from 7.95 to 10.8 g/100 g TS for the green algae U. lactuca and the red algae G. sesquipedale, respectively. Conversely, total sugars released from G. sesquipedale increased (up to 126% and 129% after VBM and CM, respectively. The best bioethanol yield (6 geth/100 g TS was reached after 72 h of fermentation of U. lactuca and no increase was obtained after centrifugal milling. The latter led to an enhancement of the ethanol yield of G. sesquipedale (from 2 to 4 g/100 g TS.

FT-IR spectroscopic analysis for studying Clostridium cell response to conversion of enzymatically hydrolyzed hay

Science.gov (United States)

Grube, Mara; Gavare, Marita; Nescerecka, Alina; Tihomirova, Kristina; Mezule, Linda; Juhna, Talis

2013-07-01

Grass hay is one of assailable cellulose containing non-food agricultural wastes that can be used as a carbohydrate source by microorganisms producing biofuels. In this study three Clostridium strains Clostridium acetobutylicum, Clostridium beijerinckii and Clostridium tetanomorphum, capable of producing acetone, butanol and ethanol (ABE) were adapted to convert enzymatically hydrolyzed hay used as a growth media additive. The results of growth curves, substrate degradation kinetics and FT-IR analyses of bacterial biomass macromolecular composition showed diverse strain-specific cell response to the growth medium composition.

Finding Biomass Degrading Enzymes Through an Activity-Correlated Quantitative Proteomics Platform (ACPP)

Science.gov (United States)

Ma, Hongyan; Delafield, Daniel G.; Wang, Zhe; You, Jianlan; Wu, Si

2017-04-01

The microbial secretome, known as a pool of biomass (i.e., plant-based materials) degrading enzymes, can be utilized to discover industrial enzyme candidates for biofuel production. Proteomics approaches have been applied to discover novel enzyme candidates through comparing protein expression profiles with enzyme activity of the whole secretome under different growth conditions. However, the activity measurement of each enzyme candidate is needed for confident "active" enzyme assignments, which remains to be elucidated. To address this challenge, we have developed an Activity-Correlated Quantitative Proteomics Platform (ACPP) that systematically correlates protein-level enzymatic activity patterns and protein elution profiles using a label-free quantitative proteomics approach. The ACPP optimized a high performance anion exchange separation for efficiently fractionating complex protein samples while preserving enzymatic activities. The detected enzymatic activity patterns in sequential fractions using microplate-based assays were cross-correlated with protein elution profiles using a customized pattern-matching algorithm with a correlation R-score. The ACPP has been successfully applied to the identification of two types of "active" biomass-degrading enzymes (i.e., starch hydrolysis enzymes and cellulose hydrolysis enzymes) from Aspergillus niger secretome in a multiplexed fashion. By determining protein elution profiles of 156 proteins in A. niger secretome, we confidently identified the 1,4-α-glucosidase as the major "active" starch hydrolysis enzyme (R = 0.96) and the endoglucanase as the major "active" cellulose hydrolysis enzyme (R = 0.97). The results demonstrated that the ACPP facilitated the discovery of bioactive enzymes from complex protein samples in a high-throughput, multiplexing, and untargeted fashion.

Process optimization in Nd:YAG laser microdrilling of alumina–aluminium interpenetrating phase composite

Directory of Open Access Journals (Sweden)

Ranjib Biswas

2015-07-01

Full Text Available In laser beam micromachining process, the quality of the drilled hole is of great importance. The quality of the microdrilled hole mainly depends on appropriate selection of process parameters. Predefined diameter of hole with minimum taper is of today's demand. The composite used for microdrilling operation is alumina–aluminium (Al2O3–Al interpenetrating phase composite (IPC, which is widely used in aircraft and space stations. Until date, no experimental study has been done to obtain microdrilled hole of desired diameter. In the present paper three hole qualities such as hole diameter at entry, at exit and hole taper have been optimized individually as well as simultaneously using a central composite design (CCD based on response surface methodology (RSM during pulsed Nd:YAG laser microdrilling operation on alumina–aluminium IPC sheet of 1.14 mm thickness. The analysis of variance (ANOVA test has also been done to identify the process parameters that contributed the most to get desired hole quality.

Preparation and characterization of shape memory composite foams with interpenetrating polymer networks

International Nuclear Information System (INIS)

Yao, Yongtao; Zhou, Tianyang; Yang, Cheng; Leng, Jinsong; Liu, Yanju

2016-01-01

The present study reports a feasible approach of fabricating shape memory composite foams with an interpenetrating polymer network (IPN) based on polyurethane (PU) and shape memory epoxy resin (SMER) via a simultaneous polymerization technique. The PU component is capable of constructing a foam structure and the SMER is grafted on the PU network to offer its shape memory property in the final IPN foams. A series of IPN foams without phase separation were produced due to good compatibility and a tight chemical interaction between PU and SMER components. The relationships of the geometry of the foam cell were investigated via varying compositions of PU and SMER. The physical property and shape memory property were also evaluated. The stimulus temperature of IPN shape memory composite foams, glass temperature (T g ), could be tunable by varying the constituents and T g of PU and SMER. The mechanism of the shape memory effect of IPN foams has been proposed. The shape memory composite foam with IPN developed in this study has the potential to extend its application field. (paper)

End-to-end gene fusions and their impact on the production of multifunctional biomass degrading enzymes

International Nuclear Information System (INIS)

Rizk, Mazen; Antranikian, Garabed; Elleuche, Skander

2012-01-01

Highlights: ► Multifunctional enzymes offer an interesting approach for biomass degradation. ► Size and conformation of separate constructs play a role in the effectiveness of chimeras. ► A connecting linker allows for maximal flexibility and increased thermostability. ► Genes with functional similarities are the best choice for fusion candidates. -- Abstract: The reduction of fossil fuels, coupled with its increase in price, has made the search for alternative energy resources more plausible. One of the topics gaining fast interest is the utilization of lignocellulose, the main component of plants. Its primary constituents, cellulose and hemicellulose, can be degraded by a series of enzymes present in microorganisms, into simple sugars, later used for bioethanol production. Thermophilic bacteria have proven to be an interesting source of enzymes required for hydrolysis since they can withstand high and denaturing temperatures, which are usually required for processes involving biomass degradation. However, the cost associated with the whole enzymatic process is staggering. A solution for cost effective and highly active production is through the construction of multifunctional enzyme complexes harboring the function of more than one enzyme needed for the hydrolysis process. There are various strategies for the degradation of complex biomass ranging from the regulation of the enzymes involved, to cellulosomes, and proteins harboring more than one enzymatic activity. In this review, the construction of multifunctional biomass degrading enzymes through end-to-end gene fusions, and its impact on production and activity by choosing the enzymes and linkers is assessed.

Mobila och semi-mobila slakterier som alternativa slaktsystem

OpenAIRE

Hedberg, Eva; Gebresenbet, Girma

1999-01-01

Mobile and semi-mobile abattoirs, in which animals can be slaughtered on the farm or near the farm, could be an alternative slaughtersystem to the conventional one. This alternative is aimed to minimize stress induced by handling and transport activities on animals prior to slaughtering, and thereby attenuate the risks for reduced meat quality. More over, minimized transport could lead to reduction of environmental degradation imposed by emissions generated from vehicles. The objective of the...

Mapping the polysaccharide degradation potential of Aspergillus niger

Science.gov (United States)

2012-01-01

Background The degradation of plant materials by enzymes is an industry of increasing importance. For sustainable production of second generation biofuels and other products of industrial biotechnology, efficient degradation of non-edible plant polysaccharides such as hemicellulose is required. For each type of hemicellulose, a complex mixture of enzymes is required for complete conversion to fermentable monosaccharides. In plant-biomass degrading fungi, these enzymes are regulated and released by complex regulatory structures. In this study, we present a methodology for evaluating the potential of a given fungus for polysaccharide degradation. Results Through the compilation of information from 203 articles, we have systematized knowledge on the structure and degradation of 16 major types of plant polysaccharides to form a graphical overview. As a case example, we have combined this with a list of 188 genes coding for carbohydrate-active enzymes from Aspergillus niger, thus forming an analysis framework, which can be queried. Combination of this information network with gene expression analysis on mono- and polysaccharide substrates has allowed elucidation of concerted gene expression from this organism. One such example is the identification of a full set of extracellular polysaccharide-acting genes for the degradation of oat spelt xylan. Conclusions The mapping of plant polysaccharide structures along with the corresponding enzymatic activities is a powerful framework for expression analysis of carbohydrate-active enzymes. Applying this network-based approach, we provide the first genome-scale characterization of all genes coding for carbohydrate-active enzymes identified in A. niger. PMID:22799883

Control of enzymatic degradation of biodegradable polymers by treatment with biosurfactants, mannosylerythritol lipids, derived from Pseudozyma spp. yeast strains.

Science.gov (United States)

Fukuoka, Tokuma; Shinozaki, Yukiko; Tsuchiya, Wataru; Suzuki, Ken; Watanabe, Takashi; Yamazaki, Toshimasa; Kitamoto, Dai; Kitamoto, Hiroko

2016-02-01

Cutinase-like esterase from the yeasts Pseudozyma antarctica (PaE) shows strong degradation activity in an agricultural biodegradable plastic (BP) model of mulch films composed of poly(butylene succinate-co-adipate) (PBSA). P. antarctica is known to abundantly produce a glycolipid biosurfactant, mannosylerythritol lipid (MEL). Here, the effects of MEL on PaE-catalyzed degradation of BPs were investigated. Based on PBSA dispersion solution, the degradation of PBSA particles by PaE was inhibited in the presence of MEL. MEL behavior on BP substrates was monitored by surface plasmon resonance (SPR) using a sensor chip coated with polymer films. The positive SPR signal shift indicated that MEL readily adsorbed and spread onto the surface of a BP film. The amount of BP degradation by PaE was monitored based on the negative SPR signal shift and was decreased 1.7-fold by MEL pretreatment. Furthermore, the shape of PBSA mulch films in PaE-containing solution was maintained with MEL pretreatment, whereas untreated films were almost completely degraded and dissolved. These results suggest that MEL covering the surface of BP film inhibits adsorption of PaE and PaE-catalyzed degradation of BPs. We applied the above results to control the microbial degradation of BP mulch films. MEL pretreatment significantly inhibited BP mulch film degradation by both PaE solution and BP-degradable microorganism. Moreover, the degradation of these films was recovered after removal of the coated MEL by ethanol treatment. These results demonstrate that the biodegradation of BP films can be readily and reversibly controlled by a physical approach using MEL.

Draft genome sequence of pectic polysaccharide-degrading moderate thermophilic bacterium Geobacillus thermodenitrificans DSM 101594

Directory of Open Access Journals (Sweden)

Raimonda Petkauskaite

Full Text Available Abstract Geobacillus thermodenitrificans DSM 101594 was isolated as a producer of extracellular thermostable pectic polysaccharide degrading enzymes. The completely sequenced genome was 3.6 Mb in length with GC content of 48.86%. A number of genes encoding enzymatic active against the high molecular weight polysaccharides of potential biotechnological importance were identified in the genome.

Enzymatic depolymerization of gum tragacanth: bifidogenic potential of low molecular weight oligosaccharides.

Science.gov (United States)

Gavlighi, Hassan Ahmadi; Michalak, Malwina; Meyer, Anne S; Mikkelsen, J Dalgaard

2013-02-13

Gum tragacanth derived from the plant "goat's horn" (Astragalus sp.) has a long history of use as a stabilizing, viscosity-enhancing agent in food emulsions. The gum contains pectinaceous arabinogalactans and fucose-substituted xylogalacturonans. In this work, gum tragacanth from Astragalus gossypinus was enzymatically depolymerized using Aspergillus niger pectinases (Pectinex BE Color). The enzymatically degraded products were divided into three molecular weight fractions via membrane separation: HAG1 10 kDa. Compositional and linkage analyses showed that these three fractions also varied with respect to composition and structural elements: HAG1 and HAG2 were enriched in arabinose, galactose, and galacturonic acid, but low in fucose and xylose, whereas HAG3 was high in (terminal) xylose, fucose, and 1,4-bonded galacturonic acid, but low in arabinose and galactose content. The growth-stimulating potential of the three enzymatically produced gum tragacanth fractions was evaluated via growth assessment on seven different probiotic strains in single-culture fermentations on Bifidobacterium longum subsp. longum (two strains), B. longum subsp. infantis (three strains), Lactobacillus acidophilus , B. lactis, and on one pathogenic strain of Clostridium perfringens . The fractions HAG1 and HAG2 consistently promoted higher growth of the probiotic strains than HAG3, especially of the three B. longum subsp. infantis strains, and the growth promotion on HAG1 and HAG2 was better than that on galactan (control). HAG3 completely inhibited the growth of the C. perfringens strain. Tragacanth gum is thus a potential source of prebiotic carbohydrates that exert no viscosity effects and which may find use as natural functional food ingredients.

Assessment of the Current State of Agropastoral Landscapes in Semi-Arid Areas of the Republic of Kalmykia with Application of Gis-Technologies

Directory of Open Access Journals (Sweden)

Mushaeva Kermen Batnasunovna

2015-04-01

Full Text Available The state of lands in arid areas of southern Russia is entirely dependent on the state of natural steppe, dry steppe and semi-desert ecosystems. The study of vegetation traditionally enjoys a commanding position in synecological studies, because plant communities form the framework of terrestrial ecosystems. In this paper we give a detailed geobothanical description of the test plots made as a result of field research in the semi-desert areas of Kalmykia. In addition, we obtained photo samples of soils that were subsequently processed, analyzed and entered into the database of soils and used as an identifier of rangeland degradation, located in the semi-arid zone of the country. The creation of this database will improve the quality of remote sensing in the region. In the course of computer processing of materials using GIS technology, the geoinformation analysis of land degradation in the studied territory was held, and the area of these lands according to the levels of degradation was calculated.

A xylanase-aided enzymatic pretreatment facilitates cellulose nanofibrillation.

Science.gov (United States)

Long, Lingfeng; Tian, Dong; Hu, Jinguang; Wang, Fei; Saddler, Jack

2017-11-01

Although biological pretreatment of cellulosic fiber based on endoglucanases has shown some promise to facilitate cellulose nanofibrillation, its efficacy is still limited. In this study, a xylanase-aided endoglucanase pretreatment was assessed on the bleached hardwood and softwood Kraft pulps to facilitate the downstream cellulose nanofibrillation. Four commercial xylanase preparations were compared and the changes of major fiber physicochemical characteristics such as cellulose/hemicellulose content, gross fiber properties, fiber morphologies, cellulose accessibility/degree of polymerization (DP)/crystallinity were systematically evaluated before and after enzymatic pretreatment. It showed that the synergistic cooperation between endoglucanase and certain xylanase (Biobrite) could efficiently "open up" the hardwood Kraft pulp with limited carbohydrates degradation (cellulose nanofibrillation during mild sonication process (90Wh) with more uniform disintegrated nanofibril products (50-150nm, as assessed by scanning electron microscopy and UV-vis spectroscopy). Copyright © 2017 Elsevier Ltd. All rights reserved.

Vapor-phase deposition of regioregular and oriented poly(3-hexylthiophene) structures and novel nanostructured composites of interpenetrating poly(3-hexylthiophene) and polyaniline exhibiting full-color wavelength (400-1000 nm) photoluminescence

Science.gov (United States)

Biswas, A.; Bayer, I. S.; Karulkar, P. C.; Tripathi, A.; Avasthi, D. K.

2007-10-01

A promising solvent-free technique of electron-beam-assisted vapor-phase codeposition method is presented which allows uniform blending of different conjugated and nonconjugated polymers at the nanoscale. The technique allows direct incorporation of regioregular poly(3-hexylthiophene) (P3HT) polymer with different structural orientations into conventional and semiconducting polymers without fractionation or degradation of P3HT while maintaining the nanoscale morphology of deposited organic films. The results of fabricated novel nanostructured organic composites (˜100-200nm) comprising regioregular and oriented P3HT and different conjugated and nonconjugated polymers including selective assembly of P3HT nanonodules into a copolymer template are presented. We show a typical example of blending of P3HT and polyaniline (PANI) that formed a unique nanoscale morphology comprising interpenetrating networks of different shapes and sizes of nanospherulites (˜100nm) of P3HT in PANI. The so fabricated nanocomposites (˜200nm) exhibited remarkable broadband photoluminescence features covering the entire blue, green, and red wavelength regions between 400 and 1000nm. Such organic nanocomposites might be useful for flexible full-color screen flat panel displays and organic white-light solid-state lighting applications.

Pretreatment of wheat straw with potassium hydroxide for increasing enzymatic and microbial degradability.

Science.gov (United States)

Liu, Xiaoying; Zicari, Steven M; Liu, Guangqing; Li, Yeqing; Zhang, Ruihong

2015-06-01

The pretreatment of wheat straw with potassium hydroxide (KOH) at ambient temperature (20°C) was investigated. The pretreatment effects on chemical composition and physical structures, and subsequent enzymatic hydrolysis and anaerobic digestion were evaluated. Wheat straw at 10% total solids (TS) was treated with KOH solution for 24h at a wide range of KOH loadings from 2% to 50% (w/w dry basis). Higher KOH loading resulted in higher lignin reduction from the straw and chemical oxygen demand (COD) in the resulting black liquor. Maximum lignin reduction of 54.7% was observed at 50% KOH loading. In comparison to untreated straw, specific hydrolysis yields achieved 14.0-92.3% over the range of 2-50% KOH loading, and methane yields increased 16.7-77.5% for KOH loadings of 10-50%, respectively. Accounting for losses during pretreatment, 20% KOH loading resulted in maximum overall reducing sugar yield and methane yield and therefore is the recommended loading for pretreatment under these conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

A 12-Fold ThSi2 Interpenetrated Network Utilizing a Glycine-Based Pseudopeptidic Ligand

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Edward Loukopoulos

2018-01-01

Full Text Available We report the synthesis and characterization of a 3D Cu(II coordination polymer, [Cu3(L12(H2O8]·8H2O (1, with the use of a glycine-based tripodal pseudopeptidic ligand (H3L1 = N,N′,N″-tris(carboxymethyl-1,3,5-benzenetricarboxamide or trimesoyl-tris-glycine. This compound presents the first example of a 12-fold interpenetrated ThSi2 (ths net. We attempt to justify the unique topology of 1 through a systematic comparison of the synthetic parameters in all reported structures with H3L1 and similar tripodal pseudopeptidic ligands. We additionally explore the catalytic potential of 1 in the A3 coupling reaction for the synthesis of propargylamines. The compound acts as a very good heterogeneous catalyst with yields up to 99% and loadings as low as 3 mol %.

High quality junctions by interpenetration of vapor liquid solid grown nanostructures for microchip integration

Energy Technology Data Exchange (ETDEWEB)

Jebril, Seid; Kuhlmann, Hanna; Adelung, Rainer [Funktionale Nanomaterialien, CAU Kiel (Germany); Mueller, Sven [Nanowires and Thin Films, II. Physikalisches Institut, Goettingen (Germany); Ronning, Carsten [Institute for Solid State Physics, Universitaet Jena (Germany); Kienle, Lorenz [Synthese und Realstruktur, CAU Kiel (Germany); Duppel, Viola [MPI fuer Festkoerperforschung, Stuttgart (Germany)

2009-07-01

The usability of nanostructures in electrical devices like gas sensors depends critically on the ability to form high quality contacts and junctions. For the fabrication of various nanostructures, vapor-liquid-solid (VLS) growth is a wide spread and very efficient technique. However, forming contacts with the VLS grown structures to utilize them in a device is still tedious, because either the substrate has to be epitaxial to the VLS material or a manual alignment is necessary. Here we demonstrate the contact formation by simply using the ability of individual crystals to interpenetrate each other during the straight forward VLS growth. This allows growing VLS structures directly on two neighboring gold circuit paths of a microchip; bridges over predefined gaps will be formed. Moreover, TEM investigations confirm the high quality of the crystalline junctions that allow demonstrations as UV and hydrogen-sensor. The VLS devices are compared with conventional produced.

Repeated batch and continuous degradation of chlorpyrifos by Pseudomonas putida.

Science.gov (United States)

Pradeep, Vijayalakshmi; Subbaiah, Usha Malavalli

2015-01-01

The present study was undertaken with the objective of studying repeated batch and continuous degradation of chlorpyrifos (O,O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) using Ca-alginate immobilized cells of Pseudomonas putida isolated from an agricultural soil, and to study the genes and enzymes involved in degradation. The study was carried out to reduce the toxicity of chlorpyrifos by degrading it to less toxic metabolites. Long-term stability of pesticide degradation was studied during repeated batch degradation of chlorpyrifos, which was carried out over a period of 50 days. Immobilized cells were able to show 65% degradation of chlorpyrifos at the end of the 50th cycle with a cell leakage of 112 × 10(3) cfu mL(-1). During continuous treatment, 100% degradation was observed at 100 mL h(-1) flow rate with 2% chlorpyrifos, and with 10% concentration of chlorpyrifos 98% and 80% degradation was recorded at 20 mL h(-1) and 100 mL h(-1) flow rate respectively. The products of degradation detected by liquid chromatography-mass spectrometry analysis were 3,5,6-trichloro-2-pyridinol and chlorpyrifos oxon. Plasmid curing experiments with ethidium bromide indicated that genes responsible for the degradation of chlorpyrifos are present on the chromosome and not on the plasmid. The results of Polymerase chain reaction indicate that a ~890-bp product expected for mpd gene was present in Ps. putida. Enzymatic degradation studies indicated that the enzymes involved in the degradation of chlorpyrifos are membrane-bound. The study indicates that immobilized cells of Ps. putida have the potential to be used in bioremediation of water contaminated with chlorpyrifos.

Production of Trametes pubescens Laccase under Submerged and Semi-Solid Culture Conditions on Agro-Industrial Wastes

Science.gov (United States)

Rodriguez, Alexander; Osma, Johann F.; Alméciga-Díaz, Carlos J.; Sánchez, Oscar F.

2013-01-01

Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametes pubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM), and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1) and 60 kDa (Lac2). Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69±0.28 U mg-1 of protein for the crude extract, and 0.08±0.001 and 2.86±0.05 U mg-1 of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct. PMID:24019936

Production of Trametes pubescens laccase under submerged and semi-solid culture conditions on agro-industrial wastes.

Science.gov (United States)

Gonzalez, Juan C; Medina, Sandra C; Rodriguez, Alexander; Osma, Johann F; Alméciga-Díaz, Carlos J; Sánchez, Oscar F

2013-01-01

Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametespubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM), and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1) and 60 kDa (Lac2). Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69 ± 0.28 U mg(-1) of protein for the crude extract, and 0.08 ± 0.001 and 2.86 ± 0.05 U mg(-1) of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct.

Production of Trametes pubescens laccase under submerged and semi-solid culture conditions on agro-industrial wastes.

Directory of Open Access Journals (Sweden)

Juan C Gonzalez

Full Text Available Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametespubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM, and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1 and 60 kDa (Lac2. Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69 ± 0.28 U mg(-1 of protein for the crude extract, and 0.08 ± 0.001 and 2.86 ± 0.05 U mg(-1 of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct.

Alginate/PEG based microcarriers with cleavable crosslinkage for expansion and non-invasive harvest of human umbilical cord blood mesenchymal stem cells

Energy Technology Data Exchange (ETDEWEB)

Li, Chunge [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, No. 92, Weijin Road, Tianjin 300072 (China); Qian, Yufeng [Department of Chemistry and Biochemistry, University of Texas at Austin, 2500 Speedway, Austin, TX 78712 (United States); Zhao, Shuang [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, No. 92, Weijin Road, Tianjin 300072 (China); Yin, Yuji, E-mail: yinyuji@tju.edu.cn [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, No. 92, Weijin Road, Tianjin 300072 (China); Li, Junjie, E-mail: li41308@tju.edu.cn [Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, No. 92, Weijin Road, Tianjin 300072 (China); Department of Advanced Interdisciplinary Studies, Institute of Basic Medical Sciences and Tissue Engineering Research Center, Academy of Military Medical Sciences, No. 27, Taiping Road, Beijing 100850 (China)

2016-07-01

Porous microcarriers are increasingly used to expand and harvest stem cells. Generally, the cells are harvested via proteolytic enzyme treatment, which always leads to damages to stem cells. To address this disadvantage, a series of alginate/PEG (AL/PEG) semi-interpenetrating network microcarriers are prepared in this study. In this AL/PEG system, the chemically cross-linked alginate networks are formed via the reaction between carboxylic acid group of alginate and di-terminated amine groups of cystamine. PEG is introduced to modulate the degradation of microcarriers, which does not participate in this cross-linked reaction, while it interpenetrates in alginate network via physical interactions. In addition, chitosan are coated on the surface of AL/PEG to improve the mechanical strength via the electrostatic interactions. Biocompatible fibronectin are also coated on these microcarriers to modulate the biological behaviors of cells seeded in microcarriers. Results suggest that the size of AL/PEG microcarriers can be modulated via adjusting the contents and molecular weight of PEG. Moreover, the microcarriers are designed to be degraded with cleavage of disulfide crosslinkage. By changing the type and concentration of reductant, the ratio of AL to PEG, and the magnitude of chitosan coating, the degradation ability of AL/PEG microcarriers can be well controlled. In addition, AL/PEG microcarriers can support the attachment and proliferation of human umbilical cord blood mesenchymal stem cells (hUCB-MSCs). More importantly, the expanded hUCB-MSCs can be detached from microcarriers after addition of reductant, which indeed reduce the cell damage caused by proteolytic enzyme treatment. Therefore, it is convinced that AL/PEG based microcarriers will be a promising candidate for large-scale expansion of hUCB-MSCs. - Graphical abstract: Alginate/PEG IPN microcarriers can support the attachment and expansion of hUCB-MSCs. More importantly, the expanded cells can be harvested

Alginate/PEG based microcarriers with cleavable crosslinkage for expansion and non-invasive harvest of human umbilical cord blood mesenchymal stem cells

International Nuclear Information System (INIS)

Li, Chunge; Qian, Yufeng; Zhao, Shuang; Yin, Yuji; Li, Junjie

2016-01-01

Porous microcarriers are increasingly used to expand and harvest stem cells. Generally, the cells are harvested via proteolytic enzyme treatment, which always leads to damages to stem cells. To address this disadvantage, a series of alginate/PEG (AL/PEG) semi-interpenetrating network microcarriers are prepared in this study. In this AL/PEG system, the chemically cross-linked alginate networks are formed via the reaction between carboxylic acid group of alginate and di-terminated amine groups of cystamine. PEG is introduced to modulate the degradation of microcarriers, which does not participate in this cross-linked reaction, while it interpenetrates in alginate network via physical interactions. In addition, chitosan are coated on the surface of AL/PEG to improve the mechanical strength via the electrostatic interactions. Biocompatible fibronectin are also coated on these microcarriers to modulate the biological behaviors of cells seeded in microcarriers. Results suggest that the size of AL/PEG microcarriers can be modulated via adjusting the contents and molecular weight of PEG. Moreover, the microcarriers are designed to be degraded with cleavage of disulfide crosslinkage. By changing the type and concentration of reductant, the ratio of AL to PEG, and the magnitude of chitosan coating, the degradation ability of AL/PEG microcarriers can be well controlled. In addition, AL/PEG microcarriers can support the attachment and proliferation of human umbilical cord blood mesenchymal stem cells (hUCB-MSCs). More importantly, the expanded hUCB-MSCs can be detached from microcarriers after addition of reductant, which indeed reduce the cell damage caused by proteolytic enzyme treatment. Therefore, it is convinced that AL/PEG based microcarriers will be a promising candidate for large-scale expansion of hUCB-MSCs. - Graphical abstract: Alginate/PEG IPN microcarriers can support the attachment and expansion of hUCB-MSCs. More importantly, the expanded cells can be harvested

Biological interactions of carbon-based nanomaterials: From coronation to degradation.

Science.gov (United States)

Bhattacharya, Kunal; Mukherjee, Sourav P; Gallud, Audrey; Burkert, Seth C; Bistarelli, Silvia; Bellucci, Stefano; Bottini, Massimo; Star, Alexander; Fadeel, Bengt

2016-02-01

Carbon-based nanomaterials including carbon nanotubes, graphene oxide, fullerenes and nanodiamonds are potential candidates for various applications in medicine such as drug delivery and imaging. However, the successful translation of nanomaterials for biomedical applications is predicated on a detailed understanding of the biological interactions of these materials. Indeed, the potential impact of the so-called bio-corona of proteins, lipids, and other biomolecules on the fate of nanomaterials in the body should not be ignored. Enzymatic degradation of carbon-based nanomaterials by immune-competent cells serves as a special case of bio-corona interactions with important implications for the medical use of such nanomaterials. In the present review, we highlight emerging biomedical applications of carbon-based nanomaterials. We also discuss recent studies on nanomaterial 'coronation' and how this impacts on biodistribution and targeting along with studies on the enzymatic degradation of carbon-based nanomaterials, and the role of surface modification of nanomaterials for these biological interactions. Advances in technology have produced many carbon-based nanomaterials. These are increasingly being investigated for the use in diagnostics and therapeutics. Nonetheless, there remains a knowledge gap in terms of the understanding of the biological interactions of these materials. In this paper, the authors provided a comprehensive review on the recent biomedical applications and the interactions of various carbon-based nanomaterials. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

An interfacially plasticized electro-responsive hydrogel for transdermal electro-activated and modulated (TEAM) drug delivery

NARCIS (Netherlands)

Indermun, S.; Choonara, Y.E.; Kumar, Pradeep; Toit, Du L.C.; Modi, G.; Luttge, R.; Pillay, V.

2014-01-01

This paper highlights the use of hydrogels in controlled drug delivery, and their application in stimuli responsive, especially electro-responsive, drug release. electro-conductive hydrogels (ECHs) displaying electro-responsive drug release were synthesized from semi-interpenetrating networks

Carbon storage capacity of semi-arid grassland soils and sequestration potentials in northern China.

Science.gov (United States)

Wiesmeier, Martin; Munro, Sam; Barthold, Frauke; Steffens, Markus; Schad, Peter; Kögel-Knabner, Ingrid

2015-10-01

Organic carbon (OC) sequestration in degraded semi-arid environments by improved soil management is assumed to contribute substantially to climate change mitigation. However, information about the soil organic carbon (SOC) sequestration potential in steppe soils and their current saturation status remains unknown. In this study, we estimated the OC storage capacity of semi-arid grassland soils on the basis of remote, natural steppe fragments in northern China. Based on the maximum OC saturation of silt and clay particles soils (grazing land, arable land, eroded areas) were estimated. The analysis of natural grassland soils revealed a strong linear regression between the proportion of the fine fraction and its OC content, confirming the importance of silt and clay particles for OC stabilization in steppe soils. This relationship was similar to derived regressions in temperate and tropical soils but on a lower level, probably due to a lower C input and different clay mineralogy. In relation to the estimated OC storage capacity, degraded steppe soils showed a high OC saturation of 78-85% despite massive SOC losses due to unsustainable land use. As a result, the potential of degraded grassland soils to sequester additional OC was generally low. This can be related to a relatively high contribution of labile SOC, which is preferentially lost in the course of soil degradation. Moreover, wind erosion leads to substantial loss of silt and clay particles and consequently results in a direct loss of the ability to stabilize additional OC. Our findings indicate that the SOC loss in semi-arid environments induced by intensive land use is largely irreversible. Observed SOC increases after improved land management mainly result in an accumulation of labile SOC prone to land use/climate changes and therefore cannot be regarded as contribution to long-term OC sequestration. © 2015 John Wiley & Sons Ltd.

Process technology for multi-enzymatic reaction systems

DEFF Research Database (Denmark)

Xue, Rui; Woodley, John M.

2012-01-01

In recent years, biocatalysis has started to provide an important green tool in synthetic organic chemistry. Currently, the idea of using multi-enzymatic systems for industrial production of chemical compounds becomes increasingly attractive. Recent examples demonstrate the potential of enzymatic...... synthesis and fermentation as an alternative to chemical-catalysis for the production of pharmaceuticals and fine chemicals. In particular, the use of multiple enzymes is of special interest. However, many challenges remain in the scale-up of a multi-enzymatic system. This review summarizes and discusses...... the technology options and strategies that are available for the development of multi-enzymatic processes. Some engineering tools, including kinetic models and operating windows, for developing and evaluating such processes are also introduced....

Enhancement of Palm Oil Extraction Using Cell Wall Degrading Enzyme Formulation

International Nuclear Information System (INIS)

Silvamany, H.; Jamaliah Md Jahim

2015-01-01

In this recent work, application of aqueous enzymatic process to enhance recovery of palm oil was studied. Experiments were carried out to investigate the structural carbohydrate composition of oil palm mesocarp (Elaeis guineensis) and to analyze the effect of different combination of enzymes on the palm oil recovery and degree of digestibility and the respective correlation. The optimum combination of enzymes comprising of Cellic CTec2 (X 1 ), Cellic HTec2 (X 2 ) and Pectinex Ultra SP-L (X 3 ) for Aqueous Enzymatic Oil Extraction Process (AEOEP), were determined using Simplex Lattice mixture design under fixed parameters. Maximum oil recovery of 88 % was achieved with ratio of enzymes at 0.46: 0.34: 0.2 (X 1 :X 2 :X 3 ), at enzyme loading of 30 mg protein/ 10 g substrate, substrate loading of 50 % w/v, pH 4.8, and 2 hours of incubation at 50 degree Celsius. The conversion of reducing sugar at corresponding condition was measured to evaluate the effectiveness of enzymes in degrading fruit cell wall releasing trapped oil. Moreover, transmission electron microscopy (TEM) was utilized to indicate the increase in cell wall disintegration leading to higher release of oil with enzymatic treatment. (author)

Degradation of di(2-ethyl hexyl) phthalate by Fusarium culmorum: Kinetics, enzymatic activities and biodegradation pathway based on quantum chemical modelingpathway based on quantum chemical modeling

International Nuclear Information System (INIS)

Ahuactzin-Pérez, Miriam; Tlecuitl-Beristain, Saúl; García-Dávila, Jorge; González-Pérez, Manuel; Gutiérrez-Ruíz, María Concepción; Sánchez, Carmen

2016-01-01

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the manufacture of plastics, and it is an environmental contaminant. The specific growth rate (μ), maximum biomass (X_m_a_x), biodegradation constant of DEHP (k), half-life (t_1_/_2) of DEHP biodegradation and removal efficiency of DEHP, esterase and laccase specific activities, and enzymatic yield parameters were evaluated for Fusarium culmorum grown on media containing glucose and different concentrations of DEHP (0, 500 and 1000 mg/L). The greatest μ and the largest X_m_a_x occurred in media supplemented with 1000 mg of DEHP/L. F. culmorum degraded 95% of the highest amount of DEHP tested (1000 mg/L) within 60 h of growth. The k and t_1_/_2 were 0.024 h"−"1 and 28 h, respectively, for both DEHP concentrations. The removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. Much higher specific esterase activity than specific laccase activity was observed in all media tested. The compounds of biodegradation of DEHP were identified by GC–MS. A DEHP biodegradation pathway by F. culmorum was proposed on the basis of the intermolecular flow of electrons of the identified intermediate compounds using quantum chemical modeling. DEHP was fully metabolized by F. culmorum with butanediol as the final product. This fungus offers great potential in bioremediation of environments polluted with DEHP. - Highlights: • F. culmorum degraded 95% of DEHP (1000 mg/L) within 60 h. • Removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. • DEHP was fully metabolized by F. culmorum, with butanediol as the final product. • A DEHP biodegradation pathway was proposed using on quantum chemical modeling.

Degradation of di(2-ethyl hexyl) phthalate by Fusarium culmorum: Kinetics, enzymatic activities and biodegradation pathway based on quantum chemical modelingpathway based on quantum chemical modeling

Energy Technology Data Exchange (ETDEWEB)

Ahuactzin-Pérez, Miriam [Doctorado en Biología Experimental, Universidad Autónoma Metropolitana-Iztapalapa (UAM-I) (Mexico); Facultad de Agrobiología, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Tlaxcala (Mexico); Tlecuitl-Beristain, Saúl; García-Dávila, Jorge [Universidad Politécnica de Tlaxcala, San Pedro Xalcatzinco, Tepeyanco, Tlaxcala CP 90180 (Mexico); González-Pérez, Manuel [Universidad Popular Autónoma del Estado de Puebla, Puebla CP 72410 (Mexico); Gutiérrez-Ruíz, María Concepción [Departamento de Ciencias de la Salud, Universidad Autónoma Metropolitana-Iztapalapa, D.F (Mexico); Sánchez, Carmen, E-mail: sanher6@hotmail.com [Laboratory of Biotechnology, Research Centre for Biological Sciences, Universidad Autónoma de Tlaxcala, Ixtacuixtla, Tlaxcala CP. 90062 (Mexico)

2016-10-01

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the manufacture of plastics, and it is an environmental contaminant. The specific growth rate (μ), maximum biomass (X{sub max}), biodegradation constant of DEHP (k), half-life (t{sub 1/2}) of DEHP biodegradation and removal efficiency of DEHP, esterase and laccase specific activities, and enzymatic yield parameters were evaluated for Fusarium culmorum grown on media containing glucose and different concentrations of DEHP (0, 500 and 1000 mg/L). The greatest μ and the largest X{sub max} occurred in media supplemented with 1000 mg of DEHP/L. F. culmorum degraded 95% of the highest amount of DEHP tested (1000 mg/L) within 60 h of growth. The k and t{sub 1/2} were 0.024 h{sup −1} and 28 h, respectively, for both DEHP concentrations. The removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. Much higher specific esterase activity than specific laccase activity was observed in all media tested. The compounds of biodegradation of DEHP were identified by GC–MS. A DEHP biodegradation pathway by F. culmorum was proposed on the basis of the intermolecular flow of electrons of the identified intermediate compounds using quantum chemical modeling. DEHP was fully metabolized by F. culmorum with butanediol as the final product. This fungus offers great potential in bioremediation of environments polluted with DEHP. - Highlights: • F. culmorum degraded 95% of DEHP (1000 mg/L) within 60 h. • Removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500 mg/L, respectively. • DEHP was fully metabolized by F. culmorum, with butanediol as the final product. • A DEHP biodegradation pathway was proposed using on quantum chemical modeling.

Swelling and Shrinking Properties of Thermo-Responsive Polymeric Ionic Liquid Hydrogels with Embedded Linear pNIPAAM

Directory of Open Access Journals (Sweden)

Simon Gallagher

2014-03-01

Full Text Available In this study, varying concentrations of linear pNIPAAM have been incorporated for the first time into a thermo-responsive polymeric ionic liquid (PIL hydrogel, namely tributyl-hexyl phosphonium 3-sulfopropylacrylate (P-SPA, to produce semi-interpenetrating polymer networks. The thermal properties of the resulting hydrogels have been investigated along with their thermo-induced shrinking and reswelling capabilities. The semi-interpenetrating networks (IPN hydrogels were found to have improved shrinking and reswelling properties compared with their PIL counterpart. At elevated temperatures (50–80 °C, it was found that the semi-IPN with the highest concentration of hydrophobic pNIPAAM exhibited the highest shrinking percentage of ~40% compared to the conventional P-SPA, (27%. This trend was also found to occur for the reswelling measurements, with semi-IPN hydrogels producing the highest reswelling percentage of ~67%, with respect to its contracted state. This was attributed to an increase in water affinity due to the presence of hydrophilic pNIPAAM. Moreover, the presence of linear pNIPAAM in the polymer matrix leads to improved shrinking and reswelling response compared to the equivalent PIL.

Monitoring land degradation with long-term satellite data in South Africa.

CSIR Research Space (South Africa)

Wessels, Konrad J

2007-01-01

Full Text Available Desertification is defined by the United Nations Convention to Combat Desertification (UNCCD) as ‘land degradation in arid, semi-arid and dry sub-humid areas (dry-lands) resulting from various factors, including climatic variations and human...

Analysis of chemical warfare using a transient semi-Markov formulation.

OpenAIRE

Kierzewski, Michael O.

1988-01-01

Approved for public release; distribution is unlimited This thesis proposes an analytical model to test various assumptions about conventional/chemical warfare. A unit's status in conventional/chemical combat is modeled as states in a semi-Markov chain with transient and absorbing states. The effects of differing chemical threat levels, availability of decontamination assets and assumed personnel degradation rates on expected unit life and capabilities are tested. The ...

The Development of English Semi-detached Dwellings During the Nineteenth Century

Directory of Open Access Journals (Sweden)

Pamela Lofthouse

2013-02-01

Full Text Available Buildings in England are heritage listed if they are of special architectural or historical interest, and based on the significance, appropriate conservation priorities can be determined.But to list, and then conserve, one must first identify, then research and assess. The problem is being able to recognise an important example of a semi-detached house (semi if it is neither very old nor aesthetically appealing. The semi is the most common dwelling type in England, yet because it is typically suburban and ordinary, very little research into its origins and development has been carried out. As a result, semis are under-represented in heritage listings. And once listed, it is difficult, if not impossible, to set priorities for ongoing conservation work or adaptive reuse, without knowledge of the historical or social underpinnings of its significance. Even those ordinary buildings which do not reach the thresholds for listing risk being unnecessarily degraded, through demolition, decay or unsympathetic alterations, if there is no understanding of their stories or meanings, and no safeguards are built into the planning guidelines.

Mapping the polysaccharide degradation potential of Aspergillus niger

Directory of Open Access Journals (Sweden)

Andersen Mikael R

2012-07-01

Full Text Available Abstract Background The degradation of plant materials by enzymes is an industry of increasing importance. For sustainable production of second generation biofuels and other products of industrial biotechnology, efficient degradation of non-edible plant polysaccharides such as hemicellulose is required. For each type of hemicellulose, a complex mixture of enzymes is required for complete conversion to fermentable monosaccharides. In plant-biomass degrading fungi, these enzymes are regulated and released by complex regulatory structures. In this study, we present a methodology for evaluating the potential of a given fungus for polysaccharide degradation. Results Through the compilation of information from 203 articles, we have systematized knowledge on the structure and degradation of 16 major types of plant polysaccharides to form a graphical overview. As a case example, we have combined this with a list of 188 genes coding for carbohydrate-active enzymes from Aspergillus niger, thus forming an analysis framework, which can be queried. Combination of this information network with gene expression analysis on mono- and polysaccharide substrates has allowed elucidation of concerted gene expression from this organism. One such example is the identification of a full set of extracellular polysaccharide-acting genes for the degradation of oat spelt xylan. Conclusions The mapping of plant polysaccharide structures along with the corresponding enzymatic activities is a powerful framework for expression analysis of carbohydrate-active enzymes. Applying this network-based approach, we provide the first genome-scale characterization of all genes coding for carbohydrate-active enzymes identified in A. niger.

Synthesis and characterization of interpenetrating phase ceramic metal composites

International Nuclear Information System (INIS)

Kanwal, T.

2011-01-01

Alumina powder was sintered in MW furnace under vacuum, without vacuum and conventional sintering furnace at different temperatures followed by characterization to observe the effect of sintering mode. Zirconia-Nickel and Alumina-Nickel systems were selected to study the effect of metallic phase interconnectivity on the electrical and thermal behavior in interpenetrating phase composites (IPCs). In order to obtain the homogenous mixture of Alumina and Nick powders, a detailed investigation was performed on the de-agglomeration and prop mixing of powders. Sintering parameters were optimized for the homogenization o Alumina with Nickel in planetary ball mill without sticking of powders with jar.- Homogenization of Zirconia-Nickel and Alumina-Nickel powders was perform using planetary ball mill as well as pestle mortar. Compaction of composites was performed uniaxially and sintering was carried in microwave furnace, tubular furnace with Argon environment and in vacuum sintering furnace. Electrical and thermal behavior of microwave as well as conventionally sintered ZrO/sub 2/-Ni and Al/sub 2/O/sub 3/-Ni IPCs was also observed. Electrical behavior of Composites was characterized b determining the impedance of the composites. To find the percolation limit for both Alumina-Nickel and Zirconia-Nickel composite systems the real part of impedance was used. On the basis of electrical characterization, samples were selected for SEM, BET surface area and CTE analysis. SEM of selected samples was performed t observe the connectivity of Nickel in composites. Finally, the effect of percolation limit on thermal behavior of IPCs was investigated with the help of CTE. (author)

Mechanical study of PLA-PCL fibers during in vitro degradation.

Science.gov (United States)

Vieira, A C; Vieira, J C; Ferra, J M; Magalhães, F D; Guedes, R M; Marques, A T

2011-04-01

The aliphatic polyesters are widely used in biomedical applications since they are susceptible to hydrolytic and/or enzymatic chain cleavage, leading to α-hydroxyacids, generally metabolized in the human body. This is particularly useful for many biomedical applications, especially, for temporary mechanical supports in regenerative medical devices. Ideally, the degradation should be compatible with the tissue recovering. In this work, the evolution of mechanical properties during degradation is discussed based on experimental data. The decrease of tensile strength of PLA-PCL fibers follows the same trend as the decrease of molecular weight, and so it can also be modeled using a first order equation. For each degradation stage, hyperelastic models such as Neo-Hookean, Mooney-Rivlin and second reduced order, allow a reasonable approximation of the material behavior. Based on this knowledge, constitutive models that describe the mechanical behavior during degradation are proposed and experimentally validated. The proposed theoretical models and methods may be adapted and used in other biodegradable materials, and can be considered fundamental tools in the design of regenerative medical devices where strain energy is an important requirement, such as, for example, ligaments, cartilage and stents. Copyright © 2010 Elsevier Ltd. All rights reserved.

Poly(lactide)-containing multifunctional nanoparticles: Synthesis, domain-selective degradation and therapeutic applicability

Science.gov (United States)

Samarajeewa, Sandani

Construction of nanoassemblies from degradable components is desired for packaging and controlled release of active therapeutics, and eventual biodegradability in vivo. In this study, shell crosslinked micelles composed of biodegradable poly(lactide) (PLA) core were prepared by the self-assembly of an amphiphilic diblock copolymer synthesized by a combination of ring opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. Enzymatic degradation of the PLA cores of the nanoparticles was achieved upon the addition of proteinase K (PK). Kinetic analyses and comparison of the properties of the nanomaterials as a function of degradation extent will be discussed. Building upon our findings from selective-excavation of the PLA core, enzyme- and redox-responsive nanoparticles were constructed for the encapsulation and stimuli-responsive release of an antitumor drug. This potent chemotherapeutic, otherwise poorly soluble in water was dispersed into aqueous solution by the supramolecular co-assembly with an amphiphilic block copolymer, and the release from within the core of these nanoparticles were gated by crosslinking the hydrophilic shell region with a reduction-responsive crosslinker. Enzyme- and reduction-triggered release behavior of the antitumor drug was demonstrated along with their remarkably high in vitro efficacy. As cationic nanoparticles are a promising class of transfection agents for nucleic acid delivery, in the next part of the study, synthetic methodologies were developed for the conversion of the negatively-charged shell of the enzymatically-degradable shell crosslinked micelles to positively-charged cationic nanoparticles for the complexation of nucleic acids. These degradable cationic nanoparticles were found to efficiently deliver and transfect plasmid DNA in vitro. The hydrolysis of the PLA core and crosslinkers of the nanocarriers may provide a mechanism for their programmed disassembly within

Interpenetrating polymer networks based on cyanate ester and fluorinated ethynyl-terminated imide oligomers

Directory of Open Access Journals (Sweden)

Y. Wen

2017-12-01

Full Text Available Highly soluble fluorinated ethynyl-terminated imide (FETI oligomers were prepared via a conventional one-step method in m-cresol, using 4, 4′-(hexafluoroisopropylidene diphthalic anhydride and 2, 2′-bis(trifluoromethyl benzidine as the monomers, and ethynylphthalic anhydride as the end-capper; then interpenetrating polymer networks (IPN were formulated from FETI oligomers and bisphenol A dicyanate ester (BADCy through a solvent-free procedure, and their thermal, mechanical, and dielectric properties were fully characterized. The curing mechanism was studied by model reactions using nitrogen nuclear magnetic resonance. As evidenced by differential scanning calorimetry analysis and rheological measurements, the FETI/BADCy blends exhibited lower curing temperature and shorter gelation time in comparison with pure BADCy due to the catalytic effects of ethynyl and residue amic acid groups. The properties of IPNs were fully compared with those of polycyanurate, and the results revealed that the incorporation of FETI into cyanate ester resins could significantly improve the toughness, glass transition temperatures, mechanical and dielectric properties of the resultant IPNs.

3D printing of an interpenetrating network hydrogel material with tunable viscoelastic properties.

Science.gov (United States)

Bootsma, Katherine; Fitzgerald, Martha M; Free, Brandon; Dimbath, Elizabeth; Conjerti, Joe; Reese, Greg; Konkolewicz, Dominik; Berberich, Jason A; Sparks, Jessica L

2017-06-01

Interpenetrating network (IPN) hydrogel materials are recognized for their unique mechanical properties. While IPN elasticity and toughness properties have been explored in previous studies, the factors that impact the time-dependent stress relaxation behavior of IPN materials are not well understood. Time-dependent (i.e. viscoelastic) mechanical behavior is a critical design parameter in the development of materials for a variety of applications, such as medical simulation devices, flexible substrate materials, cellular mechanobiology substrates, or regenerative medicine applications. This study reports a novel technique for 3D printing alginate-polyacrylamide IPN gels with tunable elastic and viscoelastic properties. The viscoelastic stress relaxation behavior of the 3D printed alginate-polyacrylamide IPN hydrogels was influenced most strongly by varying the concentration of the acrylamide cross-linker (MBAA), while the elastic modulus was affected most by varying the concentration of total monomer material. The material properties of our 3D printed IPN constructs were consistent with those reported in the biomechanics literature for soft tissues such as skeletal muscle, cardiac muscle, skin and subcutaneous tissue. Copyright © 2017 Elsevier Ltd. All rights reserved.

New Possibilities for High-Resolution, Large-Scale Ecosystem Assessment of the World's Semi-Arid Regions

Science.gov (United States)

Burney, J. A.; Goldblatt, R.

2016-12-01

Understanding drivers of land use change - and in particular, levels of ecosystem degradation - in semi-arid regions is of critical importance because these agroecosystems (1) are home to the world's poorest populations, almost all of whom depend on agriculture for their livelihoods, (2) play a critical role in the global carbon and climate cycles, and (3) have in many cases seen dramatic changes in temperature and precipitation, relative to global averages, over the past several decades. However, assessing ecosystem health (or, conversely, degradation) presents a difficult measurement problem. Established methods are very labor intensive and rest on detailed questionnaires and field assessments. High-resolution satellite imagery has a unique role semi-arid ecosystem assessment in that it can be used for rapid (or repeated) and very simple measurements of tree and shrub density, an excellent overall indicator for dryland ecosystem health. Because trees and large shrubs are more sparse in semi-arid regions, sub-meter resolution imagery in conjunction with automated image analysis can be used to assess density differences at high spatial resolution without expensive and time-consuming ground-truthing. This could be used down to the farm level, for example, to better assess the larger-scale ecosystem impacts of different management practices, to assess compliance with REDD+ carbon offset protocols, or to evaluate implementation of conservation goals. Here we present results comparing spatial and spectral remote sensing methods for semi-arid ecosystem assessment across new data sources, using the Brazilian Sertão as an example, and the implications for large-scale use in semi-arid ecosystem science.

Preparation and characterization of BADCy/MMA semi-IPN%BADCy/MMA半互穿网络的制备及性能表征

Institute of Scientific and Technical Information of China (English)

祝保林

2012-01-01

The cyanate ester resin/PMMA（BADCy/MMA-SIPN） with semi-interpenetrating polymers network were prepared by adding methyl methacrylate（MMA） monomer（synchronous synthisis）or MMA prepolymer（asynchronous synthesis）into the melting cyanate ester resin（BADCy） and caused.The bulk polymerization occurred.The effects of MMA contents on the mechanical properties and thermal performance of the BADCy/MMA-SIPN were investigated by the mechanical testing,infrared and DSC analysis.The results showed that the mechanical properties and heat resistance of the cyanate ester resin system were greatly improved by the formation of interpenetrating network.The impact strength,flexural strength and glass transition temperature were increased by 97.8%,58.6%,and 65 ℃,respectively.%在加热熔融的氰酸酯树脂（BADCy）中加入甲基丙烯酸甲酯（MMA）单体（同步合成法）或MMA预聚体（异步合成法）并引发使其发生本体聚合,制备了具有半互穿聚合物网络结构的氰酸酯树脂/聚甲基丙烯酸甲酯（BADCy/MMA-SIPN）,通过力学性能测试,红外及DSC分析研究了MMA含量对体系力学性能和热性能的影响。结果表明,互穿网絡的形成使氰酸酯树脂体系的力学性能和耐热性能都有较大的提高,冲击强度、弯曲强度及玻璃化温度分别提高了97.8%、58.6%和65℃。

Runoff controlling factors in various sized catchments in a semi-arid Mediterranean environment in Spain

NARCIS (Netherlands)

Wit, A.M.W. de

2001-01-01

Understanding land degradation in a semi-arid Mediterranean environment is very difficult because of the contributing factors: precipitation, infiltration vegetation cover and discontinuity of flow and the temporal and spatial levels of resolution at which these factors are acting. Therefore it

Recovery of rangelands : the functioning of soil seed banks in a semi-arid African savanna

NARCIS (Netherlands)

Tessema, Z.K.

2011-01-01

Rangelands in Africa provide important forage resources for herbivores; particularly perennial grasses provide grazing for domestic and wild herbivores. However, semi-arid African rangelands experience severe vegetation and soil degradation due to heavy grazing, causing negative impacts

Enzymatic hydrolysis of pretreated soybean straw

International Nuclear Information System (INIS)

Xu Zhong; Wang Qunhui; Jiang Zhaohua; Yang Xuexin; Ji Yongzhen

2007-01-01

In order to produce lactic acid, from agricultural residues such as soybean straw, which is a raw material for biodegradable plastic production, it is necessary to decompose the soybean straw into soluble sugars. Enzymatic hydrolysis is one of the methods in common use, while pretreatment is the effective way to increase the hydrolysis rate. The optimal conditions of pretreatment using ammonia and enzymatic hydrolysis of soybean straw were determined. Compared with the untreated straw, cellulose in straw pretreated by ammonia liquor (10%) soaking for 24 h at room temperature increased 70.27%, whereas hemicellulose and lignin in pretreated straw decreased to 41.45% and 30.16%, respectively. The results of infrared spectra (IR), scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis also showed that the structure and the surface of the straw were changed through pretreatment that is in favor of the following enzymatic hydrolysis. maximum enzymatic hydrolysis rate of 51.22% was achieved at a substrate concentration of 5% (w/v) at 50 deg. C and pH 4.8 using cellulase (50 fpu/g of substrate) for 36 h

Series of chiral interpenetrating 3d-4f heterometallic MOFs: Luminescent sensors and magnetic properties

Science.gov (United States)

Zhang, Xiaolei; Chen, Chen; Liu, Xiaoli; Gao, Peng; Hu, Ming

2017-09-01

Series of chiral 3d-4f heterometallic MOFs based on a multidentate terpyridyl carboxylic acid ligand have been synthesized under the solvothermal conditions, namely, [LnZnL(CO3)2(H2O)]n (Ln = Eu (1), Gd (2), Dy (3), Ho (4), Er (5), Tm (6), Yb (7), Lu (8)) (HL = 4‧-(4-carboxyphenyl)-2,2‧:6‧,2″-terpyridine). Compounds 1-8 were structurally characterized by the elemental analyses, infrared spectra, and single crystal X-ray diffractions. Compounds 1-8 exhibit the chiral interpenetrating 3D frameworks. Interestingly, 1 can serve as the luminescent sensor to detect nitrobenzene molecules with high sensitivity. The investigations on CD spectra of single crystals clearly assigned the Cotton effect, indicating that there exist two chiral enantiomers of 1-8 in the course of crystallization. The magnetic properties of 2 and 7 were exploited, respectively.

Direct electrochemistry and electrocatalysis of glucose oxidase on three-dimensional interpenetrating, porous graphene modified electrode

International Nuclear Information System (INIS)

Cui, Min; Xu, Bing; Hu, Chuangang; Shao, Hui Bo; Qu, Liangti

2013-01-01

Direct electrochemistry of glucose oxidase (GOD) on three-dimensional (3D) interpenetrating porous graphene electrodes has been reported, which have been fabricated by one-step electrochemical reduction of graphene oxide (GO) from its aqueous suspension. The electrochemically reduced GO (ERGO) modified electrodes exhibited excellent electron transfer properties for GOD and enhanced the enzyme activity and stability by the assistance of chitosan. The immobilized GOD shows a fast electron transfer with the rate constant (k s ) of 6.05 s −1 . It is worth mentioning that in the air-saturated phosphate buffer solution without any mediator, the resultant modified electrodes exhibited low detection limit of 1.7 μM with wide linear range of 0.02–3.2 mM and high sensitivity and high selectivity for measuring glucose. It would also be extended to various enzymes and bioactive molecules to develop the biosensor or other bio-electrochemical devices

Enzymatic approaches to rare sugar production.

Science.gov (United States)

Zhang, Wenli; Zhang, Tao; Jiang, Bo; Mu, Wanmeng

Rare sugars have recently attracted much attention because of their potential applications in the food, nutraceutical, and pharmaceutical industries. A systematic strategy for enzymatic production of rare sugars, named Izumoring, was developed >10years ago. The strategy consists of aldose-ketose isomerization, ketose C-3 epimerization, and monosaccharide oxidation-reduction. Recent development of the Izumoring strategy is reviewed herein, especially the genetic approaches to the improvement of rare sugar-producing enzymes and the applications of target-oriented bioconversion. In addition, novel non-Izumoring enzymatic approaches are also summarized, including enzymatic condensation, phosphorylation-dephosphorylation cascade reaction, aldose epimerization, ulosonic acid decarboxylation, and biosynthesis of rare disaccharides. Copyright © 2017 Elsevier Inc. All rights reserved.

Enantiomeric fractioning, degradation and metabolite formation of Mecoprop in subsoils with a phenoxy acid contamination history

DEFF Research Database (Denmark)

Frkova, Zuzana; Johansen, Anders; Karlson, Ulrich G.

2015-01-01

for their ability to degrade mecoprop under natural and amended conditions. Degradation of mecoprop was studied at elevated and environmentally relevant mecoprop concentrations as affected by nitrate and glucose at nitrate-reducing conditions and at a presence of oxygen (mimicking purging the soil with air. Results......As persistence and toxicity of the enantiomers of chiral pesticides are different a more comprehensive understanding of the fate of enantiomers of agrochemicals in the environment is necessary. Subsoils sampled vertically (2.5-6 m) at a site with a history of phenoxy acid contamination were used...... and enantioselectivity. Glucose hinders mecoprop degradation and changes the EF. Changing EF confirmed enzymatic dgradation of mecoprop in soils, which was well interpreted using the Michaelis-Menten kinetic model. The highest mecoprop degradation rate was measured in soils incubated at nitrate-reducing conditions...

pH-responsive and enzymatically-responsive hydrogel microparticles for the oral delivery of therapeutic proteins: Effects of protein size, crosslinking density, and hydrogel degradation on protein delivery.

Science.gov (United States)

Koetting, Michael Clinton; Guido, Joseph Frank; Gupta, Malvika; Zhang, Annie; Peppas, Nicholas A

2016-01-10

Two potential platform technologies for the oral delivery of protein therapeutics were synthesized and tested. pH-responsive poly(itaconic acid-co-N-vinyl-2-pyrrolidone) (P(IA-co-NVP)) hydrogel microparticles were tested in vitro with model proteins salmon calcitonin, urokinase, and rituximab to determine the effects of particle size, protein size, and crosslinking density on oral delivery capability. Particle size showed no significant effect on overall delivery potential but did improve percent release of encapsulated protein over the micro-scale particle size range studied. Protein size was shown to have a significant impact on the delivery capability of the P(IA-co-NVP) hydrogel. We show that when using P(IA-co-NVP) hydrogel microparticles with 3 mol% tetra(ethylene glycol) dimethacrylate crosslinker, a small polypeptide (salmon calcitonin) loads and releases up to 45 μg/mg hydrogel while the mid-sized protein urokinase and large monoclonal antibody rituximab load and release only 19 and 24 μg/mg hydrogel, respectively. We further demonstrate that crosslinking density offers a simple method for tuning hydrogel properties to variously sized proteins. Using 5 mol% TEGDMA crosslinker offers optimal performance for the small peptide, salmon calcitonin, whereas lower crosslinking density of 1 mol% offers optimal performance for the much larger protein rituximab. Finally, an enzymatically-degradable hydrogels of P(MAA-co-NVP) crosslinked with the peptide sequence MMRRRKK were synthesized and tested in simulated gastric and intestinal conditions. These hydrogels offer ideal loading and release behavior, showing no degradative release of encapsulated salmon calcitonin in gastric conditions while yielding rapid and complete release of encapsulated protein within 1h in intestinal conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Dynamic model of organic pollutant degradation in three dimensional packed bed electrode reactor.

Science.gov (United States)

Pang, Tianting; Wang, Yan; Yang, Hui; Wang, Tianlei; Cai, Wangfeng

2018-04-21

A dynamic model of semi-batch three-dimensional electrode reactor was established based on the limiting current density, Faraday's law, mass balance and a series of assumptions. Semi-batch experiments of phenol degradation were carried out in a three-dimensional electrode reactor packed with activated carbon under different conditions to verify the model. The factors such as the current density, the electrolyte concentration, the initial pH value, the flow rate of organic and the initial organic concentration were examined to know about the pollutant degradation in the three-dimensional electrode reactor. The various concentrations and logarithm of concentration of phenol with time were compared with the dynamic model. It was shown that the calculated data were in good agreement with experimental data in most cases. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

Science.gov (United States)

Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

2018-06-15

The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

Understanding of alkaline pretreatment parameters for corn stover enzymatic saccharification

Directory of Open Access Journals (Sweden)

Chen Ye

2013-01-01

Full Text Available Abstract Background Previous research on alkaline pretreatment has mainly focused on optimization of the process parameters to improve substrate digestibility. To achieve satisfactory sugar yield, extremely high chemical loading and enzyme dosages were typically used. Relatively little attention has been paid to reduction of chemical consumption and process waste management, which has proven to be an indispensable component of the bio-refineries. To indicate alkali strength, both alkali concentration in pretreatment solution (g alkali/g pretreatment liquor or g alkali/L pretreatment liquor and alkali loading based on biomass solids (g alkali/g dry biomass have been widely used. The dual approaches make it difficult to compare the chemical consumption in different process scenarios while evaluating the cost effectiveness of this pretreatment technology. The current work addresses these issues through pretreatment of corn stover at various combinations of pretreatment conditions. Enzymatic hydrolysis with different enzyme blends was subsequently performed to identify the effects of pretreatment parameters on substrate digestibility as well as process operational and capital costs. Results The results showed that sodium hydroxide loading is the most dominant variable for enzymatic digestibility. To reach 70% glucan conversion while avoiding extensive degradation of hemicellulose, approximately 0.08 g NaOH/g corn stover was required. It was also concluded that alkali loading based on total solids (g NaOH/g dry biomass governs the pretreatment efficiency. Supplementing cellulase with accessory enzymes such as α-arabinofuranosidase and β-xylosidase significantly improved the conversion of the hemicellulose by 6–17%. Conclusions The current work presents the impact of alkaline pretreatment parameters on the enzymatic hydrolysis of corn stover as well as the process operational and capital investment costs. The high chemical consumption for alkaline

Environmental performance of an innovative waste refinery based on enzymatic treatment

DEFF Research Database (Denmark)

Tonini, Davide; Astrup, Thomas

2011-01-01

for virgin material and saving fossil resources. In this paper a life-cycle assessment of a pilot-scale waste refinery for the enzymatic treatment of municipal solid waste (MSW) is presented. The refinery produced a liquid (liquefied organic materials and paper) and a solid fraction (non-degradable materials......Decrease of fossil fuel dependence and global warming mitigation has become increasingly important issues during the last decades. With respect to waste management higher recycling rates for valuable materials as well as energy recovery from waste streams could play a significant role substituting......) from the waste. The waste refinery was compared to alternative treatments such as incineration, bioreactor landfill and mechanical-biological treatment followed by utilization of the RDF (refuse-derived fuel) for energy. The performance of the waste refinery turned out to be comparable...

Bovine intestinal bacteria inactivate and degrade ceftiofur and ceftriaxone with multiple beta-lactamases.

Science.gov (United States)

Wagner, R Doug; Johnson, Shemedia J; Cerniglia, Carl E; Erickson, Bruce D

2011-11-01

The veterinary cephalosporin drug ceftiofur is rapidly degraded in the bovine intestinal tract. A cylinder-plate assay was used to detect microbiologically active ceftiofur, and high-performance liquid chromatography-mass spectrometry analysis was used to quantify the amount of ceftiofur remaining after incubation with bovine intestinal anaerobic bacteria, which were isolated from colon contents or feces from 8 cattle. Ninety-six percent of the isolates were able to inactivate ceftiofur to some degree, and 54% actually degraded the drug. None of 9 fungal isolates inactivated or degraded ceftiofur. Facultative and obligate anaerobic bacterial species that inactivated or degraded ceftiofur were identified with Vitek and Biolog systems, respectively. A subset of ceftiofur degraders also degraded the chemically similar drug ceftriaxone. Most of the species of bacteria that degraded ceftiofur belonged to the genera Bacillus and Bacteroides. PCR analysis of bacterial DNA detected specific β-lactamase genes. Bacillus cereus and B. mycoides isolates produced extended-spectrum β-lactamases and metallo-β-lactamases. Seven isolates of Bacteroides spp. produced multiple β-lactamases, including possibly CepA, and metallo-β-lactamases. Isolates of Eubacterium biforme, Bifidobacterium breve, and several Clostridium spp. also produced ceftiofur-degrading β-lactamases. An agar gel overlay technique on isoelectric focusing separations of bacterial lysates showed that β-lactamase enzymes were sufficient to degrade ceftiofur. These results suggest that ceftiofur is inactivated nonenzymatically and degraded enzymatically by multiple β-lactamases from bacteria in the large intestines of cattle.

Bovine Intestinal Bacteria Inactivate and Degrade Ceftiofur and Ceftriaxone with Multiple β-Lactamases▿

Science.gov (United States)

Wagner, R. Doug; Johnson, Shemedia J.; Cerniglia, Carl E.; Erickson, Bruce D.

2011-01-01

The veterinary cephalosporin drug ceftiofur is rapidly degraded in the bovine intestinal tract. A cylinder-plate assay was used to detect microbiologically active ceftiofur, and high-performance liquid chromatography-mass spectrometry analysis was used to quantify the amount of ceftiofur remaining after incubation with bovine intestinal anaerobic bacteria, which were isolated from colon contents or feces from 8 cattle. Ninety-six percent of the isolates were able to inactivate ceftiofur to some degree, and 54% actually degraded the drug. None of 9 fungal isolates inactivated or degraded ceftiofur. Facultative and obligate anaerobic bacterial species that inactivated or degraded ceftiofur were identified with Vitek and Biolog systems, respectively. A subset of ceftiofur degraders also degraded the chemically similar drug ceftriaxone. Most of the species of bacteria that degraded ceftiofur belonged to the genera Bacillus and Bacteroides. PCR analysis of bacterial DNA detected specific β-lactamase genes. Bacillus cereus and B. mycoides isolates produced extended-spectrum β-lactamases and metallo-β-lactamases. Seven isolates of Bacteroides spp. produced multiple β-lactamases, including possibly CepA, and metallo-β-lactamases. Isolates of Eubacterium biforme, Bifidobacterium breve, and several Clostridium spp. also produced ceftiofur-degrading β-lactamases. An agar gel overlay technique on isoelectric focusing separations of bacterial lysates showed that β-lactamase enzymes were sufficient to degrade ceftiofur. These results suggest that ceftiofur is inactivated nonenzymatically and degraded enzymatically by multiple β-lactamases from bacteria in the large intestines of cattle. PMID:21876048

Soil degradation effect on biological activity in Mediterranean calcareous soils

Science.gov (United States)

Roca-Pérez, L.; Alcover-Sáez, S.; Mormeneo, S.; Boluda, R.

2009-04-01

Soil degradation processes include erosion, organic matter decline, compaction, salinization, landslides, contamination, sealing and biodiversity decline. In the Mediterranean region the climatological and lithological conditions, together with relief on the landscape and anthropological activity are responsible for increasing desertification process. It is therefore considered to be extreme importance to be able to measure soil degradation quantitatively. We studied soil characteristics, microbiological and biochemical parameters in different calcareous soil sequences from Valencia Community (Easter Spain), in an attempt to assess the suitability of the parameters measured to reflect the state of soil degradation and the possibility of using the parameters to assess microbiological decline and soil quality. For this purpose, forest, scrubland and agricultural soil in three soil sequences were sampled in different areas. Several sensors of the soil biochemistry and microbiology related with total organic carbon, microbial biomass carbon, soil respiration, microorganism number and enzyme activities were determined. The results show that, except microorganism number, these parameters are good indicators of a soil biological activity and soil quality. The best enzymatic activities to use like indicators were phosphatases, esterases, amino-peptidases. Thus, the enzymes test can be used as indicators of soil degradation when this degradation is related with organic matter losses. There was a statistically significant difference in cumulative O2 uptake and extracellular enzymes among the soils with different degree of degradation. We would like to thank Spanish government-MICINN for funding and support (MICINN, project CGL2006-09776).

Oxidative degradation and non-enzymatic browning due to the interaction between oxidised lipids and primary amine groups in different marine PL emulsions

DEFF Research Database (Denmark)

Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

2012-01-01

investigated through the measurement of secondary volatile compounds by solid-phase microextraction (SPME) and dynamic headspace (DHS) connected to gas chromatography (GC–MS). Non-enzymatic browning reactions were investigated through the measurement of Strecker derived volatiles, colour changes and pyrrole...

Enzymatic production of N-acetyl-d-glucosamine from crayfish shell wastes pretreated via high pressure homogenization.

Science.gov (United States)

Wei, Guoguang; Zhang, Alei; Chen, Kequan; Ouyang, Pingkai

2017-09-01

This study presents an efficient pretreatment of crayfish shell using high pressure homogenization that enables N-acetyl-d-glucosamine (GlcNAc) production by chitinase. Firstly, the chitinase from Serratia proteamaculans NJ303 was screened for its ability to degrade crayfish shell and produce GlcNAc as the sole product. Secondly, high pressure homogenization, which caused the crayfish shell to adopt a fluffy netted structure that was characterized by Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), was evaluated as the best pretreatment method. In addition, the optimal conditions of high pressure homogenization of crayfish shell were determined to be five cycles at a pressure of 400bar, which achieved a yield of 3.9g/L of GlcNAc from 25g/L of crayfish shell in a batch enzymatic reaction over 1.5h. The results showed high pressure homogenization might be an efficient method for direct utilization of crayfish shell for enzymatic production of GlcNAc. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of Enzymatic Activity of MlrB and MlrC Proteins Involved in Bacterial Degradation of Cyanotoxins Microcystins.

Science.gov (United States)

Dziga, Dariusz; Zielinska, Gabriela; Wladyka, Benedykt; Bochenska, Oliwia; Maksylewicz, Anna; Strzalka, Wojciech; Meriluoto, Jussi

2016-03-16

Bacterial degradation of toxic microcystins produced by cyanobacteria is a common phenomenon. However, our understanding of the mechanisms of these processes is rudimentary. In this paper several novel discoveries regarding the action of the enzymes of the mlr cluster responsible for microcystin biodegradation are presented using recombinant proteins. In particular, the predicted active sites of the recombinant MlrB and MlrC were analyzed using functional enzymes and their inactive muteins. A new degradation intermediate, a hexapeptide derived from linearized microcystins by MlrC, was discovered. Furthermore, the involvement of MlrA and MlrB in further degradation of the hexapeptides was confirmed and a corrected biochemical pathway of microcystin biodegradation has been proposed.

Characterization of Enzymatic Activity of MlrB and MlrC Proteins Involved in Bacterial Degradation of Cyanotoxins Microcystins

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Dariusz Dziga

2016-03-01

Full Text Available Bacterial degradation of toxic microcystins produced by cyanobacteria is a common phenomenon. However, our understanding of the mechanisms of these processes is rudimentary. In this paper several novel discoveries regarding the action of the enzymes of the mlr cluster responsible for microcystin biodegradation are presented using recombinant proteins. In particular, the predicted active sites of the recombinant MlrB and MlrC were analyzed using functional enzymes and their inactive muteins. A new degradation intermediate, a hexapeptide derived from linearized microcystins by MlrC, was discovered. Furthermore, the involvement of MlrA and MlrB in further degradation of the hexapeptides was confirmed and a corrected biochemical pathway of microcystin biodegradation has been proposed.

Silk sericin/polyacrylamide in situ forming hydrogels for dermal reconstruction.

Science.gov (United States)

Kundu, Banani; Kundu, Subhas C

2012-10-01

In situ forming tissue sealants are advantageous due to ease in application, complete coverage of defect site and assured comfort levels to patients. The interconnected three-dimensional hydrophilic networks perfectly manage typical dermal wounds by suitably scaffolding skin fibroblast, diffusing the nutrients, therapeutics and exudates while still maintaining an adequately moist environment. We evaluate the cell homing ability of semi-interpenetrating non-mulberry tropical tasar silk sericin/polyacrylamide hydrophilic network with a keen understanding of its network characteristics and correlation of protein concentration with the performance as cell scaffold. Interconnectivity of porous networks observed through scanning electron micrograph revealed pore sizes ranging from 23 to 52 μm. The enhanced β-sheet content with the increasing sericin concentration in far red spectroscopy study supported their corresponding improved compressive strength. These semi-interpenetrating networks were found to possess a maximum fluid uptake of 112% of its weight, hence preventing the accumulation of exudates at the wound area. The present systems appear to possess characteristics like rapid gelation (~5min) at 37 °C, 98% porosity enabling the migration of fibroblasts during healing (observed through confocal and scanning electron micrographs), cell adhesion together with the absence of any cyto-toxic effect suggesting its potential as in situ tissue sealants. The compressive strength up to 61 kPa ensured ease in handling even when wet. The results prove the suitability to use non-mulberry tasar cocoon silk sericin/polyacrylamide semi-interpenetrating network as a reconstructive dermal sealant. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development of land degradation spectral indices in a semi-arid Mediterranean ecosystem

Science.gov (United States)

Chabrillat, Sabine; Kaufmann, Hermann J.; Palacios-Orueta, Alicia; Escribano, Paula; Mueller, Andreas

2004-10-01

The goal of this study is to develop remote sensing desertification indicators for drylands, in particular using the capabilities of imaging spectroscopy (hyperspectral imagery) to derive soil and vegetation specific properties linked to land degradation status. The Cabo de Gata-Nijar Natural Park in SE Spain presents a still-preserved semiarid Mediterranean ecosystem that has undergone several changes in landscape patterns and vegetation cover due to human activity. Previous studies have revealed that traditional land uses, particularly grazing, favoured in the Park the transition from tall arid brush to tall grass steppe. In the past ~40 years, tall grass steppes and arid garrigues increased while crop field decreased, and tall arid brushes decreased but then recovered after the area was declared a Natural Park in 1987. Presently, major risk is observed from a potential effect of exponential tourism and agricultural growth. A monitoring program has been recently established in the Park. Several land degradation parcels presenting variable levels of soil development and biological activity were defined in summer 2003 in agricultural lands, calcareous and volcanic areas, covering the park spatial dynamics. Intensive field spectral campaigns took place in Summer 2003 and May 2004 to monitor inter-annual changes, and assess the landscape spectral variability in spatial and temporal dimension, from the dry to the green season. Up to total 1200 field spectra were acquired over ~120 targets each year in the land degradation parcels. The targets were chosen to encompass the whole range of rocks, soils, lichens, and vegetation that can be observed in the park. Simultaneously, acquisition of hyperspectral images was performed with the HyMap sensor. This paper presents preliminary results from mainly the field spectral campaigns. Identifying sources of variability in the spectra, in relation with the ecosystem dynamics, will allow the definition of spectral indicators of

Inhibition of tyrosinase-mediated enzymatic browning by sulfite and natural alternatives

NARCIS (Netherlands)

Kuijpers, T.F.M.; Vincken, J.P.

2013-01-01

Although sulfite is widely used to counteract enzymatic browning, its mechanism has remained largely unknown. We describe a double inhibitory mechanism of sulfite on enzymatic browning, affecting both the enzymatic oxidation of phenols into o‑quinones, as well as the non‑enzymatic

Combined enzymatic hydrolysis and fermentation of aspenwood using enzymes derived from Trichoderma harzianum E58

Energy Technology Data Exchange (ETDEWEB)

1989-05-01

A project was initiated to study the conversion of aspenwood to ethanol, butanol or butanediol. The conversion method consisted of steam explosion pretreatment, followed by the enzymatic hydrolysis of the carbohydrate polymers, cellulose and hemicellulose. The enzyme was derived from a wild strain of the fungus Trichoderma harzianum E58, chosen because it produces a cellulose system that can degrade crystalline cellulose to glucose. The aspenwood was steamed at 240{degree}C for 80 seconds and then water and alkali extracted. The insoluble residue was 84% cellulose and was used for both enzyme production and the production of glucose, which was fermented to ethanol. Before fermentation of the water-soluble fraction was possible, the acetylxylan had to be hydrolyzed and the inhibitors (glucose, galactose, acetic and uronic acids, and lignin- and sugar-degradation products) removed. Enzymatic hydrolysis was found to generate less fermentation inhibitors than sulfuric acid hydrolysis. Due to market factors, fermentation research centred on the production of ethanol from hemicellulose, using the yeast Pichia stipitis. Although lignin had no effect on hydrolysis, it increased the bulk to be handled, in combination with small amounts of cellulose was found to strongly adsorb the cellulose enzymes, and broke down to produce inhibitors of the cellulose complex of T. harzanium and the enzyme production phase. Thus, it was advantageous to remove the lignin prior to enzyme production and cellular hydrolysis. None of the strategies were successful in decreasing the amount of cellulose required for enzyme production. It was concluded that T. harzianum E58 is unsuitable for use in a commercial bioconversion project. 59 refs., 31 figs., 31 tabs.

Insight into Enzymatic Degradation of Corn, Wheat, and Soybean Cell Wall Cellulose Using Quantitative Secretome Analysis of Aspergillus fumigatus.

Science.gov (United States)

Sharma Ghimire, Prakriti; Ouyang, Haomiao; Wang, Qian; Luo, Yuanming; Shi, Bo; Yang, Jinghua; Lü, Yang; Jin, Cheng

2016-12-02

Lignocelluloses contained in animal forage cannot be digested by pigs or poultry with 100% efficiency. On contrary, Aspergillus fumigatus, a saprophytic filamentous fungus, is known to harbor 263 glycoside hydrolase encoding genes, suggesting that A. fumigatus is an efficient lignocellulose degrader. Hence the present study uses corn, wheat, or soybean as a sole carbon source to culture A. fumigatus under animal physiological condition to understand how cellulolytic enzymes work together to achieve an efficient degradation of lignocellulose. Our results showed that A. fumigatus produced different sets of enzymes to degrade lignocelluloses derived from corn, wheat, or soybean cell wall. In addition, the cellulolytic enzymes produced by A. fumigatus were stable under acidic condition or at higher temperatures. Using isobaric tags for a relative and absolute quantification (iTRAQ) approach, a total of ∼600 extracellular proteins were identified and quantified, in which ∼50 proteins were involved in lignocellulolysis, including cellulases, hemicellulases, lignin-degrading enzymes, and some hypothetical proteins. Data are available via ProteomeXchange with identifier PXD004670. On the basis of quantitative iTRAQ results, 14 genes were selected for further confirmation by RT-PCR. Taken together, our results indicated that the expression and regulation of lignocellulolytic proteins in the secretome of A. fumigatus were dependent on both nature and complexity of cellulose, thus suggesting that a different enzyme system is required for degradation of different lignocelluloses derived from plant cells. Although A. fumigatus is a pathogenic fungus and cannot be directly used as an enzyme source, as an efficient lignocellulose degrader its strategy to synergistically degrade various lignocelluloses with different enzymes can be used to design enzyme combination for optimal digestion and absorption of corn, wheat, or soybean that are used as forage of pig and poultry.

Bioelectrocatalytic NAD+/NADH inter-conversion: transformation of an enzymatic fuel cell into an enzymatic redox flow battery.

Science.gov (United States)

Quah, Timothy; Milton, Ross D; Abdellaoui, Sofiene; Minteer, Shelley D

2017-07-25

Diaphorase and a benzylpropylviologen redox polymer were combined to create a bioelectrode that can both oxidize NADH and reduce NAD + . We demonstrate how bioelectrocatalytic NAD + /NADH inter-conversion can transform a glucose/O 2 enzymatic fuel cell (EFC) with an open circuit potential (OCP) of 1.1 V into an enzymatic redox flow battery (ERFB), which can be rapidly recharged by operation as an EFC.

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 31; Issue 2. Studies on in vitro release of CPM from semi-interpenetrating polymer network (IPN) composed of chitosan and glutamic acid. K Kumari P P Kundu. Polymers Volume 31 Issue 2 April 2008 pp 159-167 ...

Evaluating the mechanical properties of E-Glass fiber/carbon fiber reinforced interpenetrating polymer networks

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G. Suresh

2015-02-01

Full Text Available A series of vinyl ester and polyurethane interpenetrating polymer networks were prepared by changing the component ratios of VER (Vinyl ester and PU (Polyurethane and the polymerization process was confirmed with Fourier Transform infrared spectroscopy. IPN (Inter Penetrating Polymer Network - VER/PU reinforced Glass and carbon fiber composite laminates were made using the Hand lay up technique. The Mechanical properties of the E-glass and carbon fiber specimens were compared from tests including Tensile, Compressive, Flexural, ILSS (Inter Laminar Shear Strength, Impact & Head Deflection Test (HDT. The IPN Reinforced Carbon fiber specimen showed better results in all the tests than E-Glass fibre reinforced IPN laminate with same thickness of the specimen, according to ASTM standards. It was found that the combination of 60%VER and 40%PU IPN exhibits better impact strength and maximum elongation at break, but at the slight expense of mechanical properties such as tensile, compressive, flexural, ILSS properties. The morphology of the unreinforced and reinforced composites was analyzed with help of scanning electron microscopy.

Improved enzymatic production of phenolated glycerides through alkyl phenolate intermediate

DEFF Research Database (Denmark)

Yang, Zhiyong; Feddern, Vivian; Glasius, Marianne

2011-01-01

This work reported a novel approach for synthesis of dihydrocaffoylated glycerides, consisting of 2 steps: enzymatic synthesis of octyl dihydrocaffeate (as a synthetic intermediate) from octanol and dihydrocaffeic acid (DHCA), and enzymatic interesterification of triglycerides with octyl dihydroc......This work reported a novel approach for synthesis of dihydrocaffoylated glycerides, consisting of 2 steps: enzymatic synthesis of octyl dihydrocaffeate (as a synthetic intermediate) from octanol and dihydrocaffeic acid (DHCA), and enzymatic interesterification of triglycerides with octyl...

Evaluation of Fibrin-Based Interpenetrating Polymer Networks as Potential Biomaterials for Tissue Engineering

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Olfat Gsib

2017-12-01

Full Text Available Interpenetrating polymer networks (IPNs have gained great attention for a number of biomedical applications due to their improved properties compared to individual components alone. In this study, we investigated the capacity of newly-developed naturally-derived IPNs as potential biomaterials for tissue engineering. These IPNs combine the biologic properties of a fibrous fibrin network polymerized at the nanoscale and the mechanical stability of polyethylene oxide (PEO. First, we assessed their cytotoxicity in vitro on L929 fibroblasts. We further evaluated their biocompatibility ex vivo with a chick embryo organotypic culture model. Subcutaneous implantations of the matrices were subsequently conducted on nude mice to investigate their biocompatibility in vivo. Our preliminary data highlighted that our biomaterials were non-cytotoxic (viability above 90%. The organotypic culture showed that the IPN matrices induced higher cell adhesion (across all the explanted organ tissues and migration (skin, intestine than the control groups, suggesting the advantages of using a biomimetic, yet mechanically-reinforced IPN-based matrix. We observed no major inflammatory response up to 12 weeks post implantation. All together, these data suggest that these fibrin-based IPNs are promising biomaterials for tissue engineering.

Enzymatic degradation of hybrid iota-/nu-carrageenan by Alteromonas fortis iota-carrageenase.

Science.gov (United States)

Jouanneau, Diane; Boulenguer, Patrick; Mazoyer, Jacques; Helbert, William

2010-05-07

Hybrid iota-/nu-carrageenan was water-extracted from Eucheuma denticulatum and incubated with Alteromonas fortis iota-carrageenase. The degradation products were then separated by anion-exchange chromatography. The three most abundant fractions of hybrid iota-/nu-carrageenan oligosaccharides were purified and their structures were analyzed by NMR. The smallest hybrid was an octasaccharide with a iota-iota-nu-iota structure. The second fraction was composed of two decasaccharides with iota-iota-iota-nu-iota and iota-[iota/nu]-iota-iota structures. The third fraction was a mixture of dodecasaccharides which contained at least a iota-iota-iota-iota-nu-iota oligosaccharide. The carbon and proton NMR spectra of the octasaccharides were completely assigned, thereby completely attributing the nu-carrabiose moiety for the first time.

The degradation of phytate by microbial and wheat phytases is dependent on the phytate matrix and the phytase origin

DEFF Research Database (Denmark)

Brejnholt, Sarah M; Dionisio, Giuseppe; Glitsoe, Vibe

2011-01-01

BACKGROUND: Phytases increase utilization of phytate phosphorus in feed. Since wheat is rich in endogenous phytase activity it was examined whether wheat phytases could improve phytate degradation compared to microbial phytases. Moreover, it was investigated whether enzymatic degradation of phytate...... is influenced by the matrix surrounding it. Phytate degradation was defined as the decrease in the sum of InsP6 + InsP5. RESULTS: Endogenous wheat phytase effectively degraded wheat InsP6 + InsP5 at pH 4 and pH 5, while this was not true for a recombinant wheat phytase or phytase extracted from wheat bran. Only...... microbial phytases were able to degrade InsP6 + InsP5 in the entire pH range from 3 to 5, which is relevant for feed applications. A microbial phytase was efficient towards InsP6 + InsP5 in different phytate samples, whereas the ability to degrade InsP6 + InsP5 in the different phytate samples ranged from...

Structural and enzymatic characterization of the phosphotriesterase OPHC2 from Pseudomonas pseudoalcaligenes.

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Guillaume Gotthard

Full Text Available BACKGROUND: Organophosphates (OPs are neurotoxic compounds for which current methods of elimination are unsatisfactory; thus bio-remediation is considered as a promising alternative. Here we provide the structural and enzymatic characterization of the recently identified enzyme isolated from Pseudomonas pseudoalcaligenes dubbed OPHC2. OPHC2 belongs to the metallo-β-lactamase superfamily and exhibits an unusual thermal resistance and some OP degrading abilities. PRINCIPAL FINDINGS: The X-ray structure of OPHC2 has been solved at 2.1 Å resolution. The enzyme is roughly globular exhibiting a αβ/βα topology typical of the metallo-β-lactamase superfamily. Several structural determinants, such as an extended dimerization surface and an intramolecular disulfide bridge, common features in thermostable enzymes, are consistent with its high Tm (97.8°C. Additionally, we provide the enzymatic characterization of OPHC2 against a wide range of OPs, esters and lactones. SIGNIFICANCE: OPHC2 possesses a broad substrate activity spectrum, since it hydrolyzes various phosphotriesters, esters, and a lactone. Because of its organophosphorus hydrolase activity, and given its intrinsic thermostability, OPHC2 is an interesting candidate for the development of an OPs bio-decontaminant. Its X-ray structure shed light on its active site, and provides key information for the understanding of the substrate binding mode and catalysis.

A Simple Method To Demonstrate the Enzymatic Production of Hydrogen from Sugar

Science.gov (United States)

Hershlag, Natalie; Hurley, Ian; Woodward, Jonathan

1998-10-01

There is current interest in and concern for the development of environmentally friendly bioprocesses whereby biomass and the biodegradable content of municipal wastes can be converted to useful forms of energy. For example, cellulose, a glucose polymer that is the principal component of biomass and paper waste, can be enzymatically degraded to glucose, which can subsequently be converted by fermentation or further enzymatic reaction to fuels such as ethanol or hydrogen. These products represent alternative energy sources to fossil fuels such as oil. Demonstration of the relevant reactions in high-school and undergraduate college laboratories would have value not only in illustrating environmentally friendly biotechnology for the utilization of renewable energy sources, such as cellulosic wastes, but could also be used to teach the principles of enzyme-catalyzed reactions. In the experimental protocol described here, it has been demonstrated that the common sugar glucose can be used to produce hydrogen using two enzymes, glucose dehydrogenase and hydrogenase. No sophisticated or expensive hydrogen detection equipment is required-only a redox dye, benzyl viologen, which turns purple when it is reduced. The color can be detected by a simple colorimeter. Furthermore, it is shown that the renewable resource cellulose, in its soluble derivative from carboxymethylcellulose, as well as aspen-wood waste, is also a source of hydrogen if the enzyme cellulase is included in the reaction mixture.

Dentin matrix degradation by host Matrix Metalloproteinases: inhibition and clinical perspectives towards regeneration.

Directory of Open Access Journals (Sweden)

Catherine eChaussain

2013-11-01

Full Text Available Bacterial enzymes have long been considered solely accountable for the degradation of the dentin matrix during the carious process. However, the emerging literature suggests that host-derived enzymes, and in particular the matrix metalloproteinases (MMPs contained in dentin and saliva can play a major role in this process by their ability to degrade the dentin matrix from within. These findings are important since they open new therapeutic options for caries prevention and treatment. The possibility of using MMP inhibitors to interfere with dentin caries progression is discussed. Furthermore, the potential release of bioactive peptides by the enzymatic cleavage of dentin matrix proteins by MMPs during the carious process is discussed. These peptides, once identified, may constitute promising therapeutical tools for tooth and bone regeneration.

SemiBoost: boosting for semi-supervised learning.

Science.gov (United States)

Mallapragada, Pavan Kumar; Jin, Rong; Jain, Anil K; Liu, Yi

2009-11-01

Semi-supervised learning has attracted a significant amount of attention in pattern recognition and machine learning. Most previous studies have focused on designing special algorithms to effectively exploit the unlabeled data in conjunction with labeled data. Our goal is to improve the classification accuracy of any given supervised learning algorithm by using the available unlabeled examples. We call this as the Semi-supervised improvement problem, to distinguish the proposed approach from the existing approaches. We design a metasemi-supervised learning algorithm that wraps around the underlying supervised algorithm and improves its performance using unlabeled data. This problem is particularly important when we need to train a supervised learning algorithm with a limited number of labeled examples and a multitude of unlabeled examples. We present a boosting framework for semi-supervised learning, termed as SemiBoost. The key advantages of the proposed semi-supervised learning approach are: 1) performance improvement of any supervised learning algorithm with a multitude of unlabeled data, 2) efficient computation by the iterative boosting algorithm, and 3) exploiting both manifold and cluster assumption in training classification models. An empirical study on 16 different data sets and text categorization demonstrates that the proposed framework improves the performance of several commonly used supervised learning algorithms, given a large number of unlabeled examples. We also show that the performance of the proposed algorithm, SemiBoost, is comparable to the state-of-the-art semi-supervised learning algorithms.

CELLULOSE DEGRADATION BY OXIDATIVE ENZYMES

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Maria Dimarogona

2012-09-01

Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

Enzymatic desulfurization of coal

Energy Technology Data Exchange (ETDEWEB)

Boyer, Y.N.; Crooker, S.C.; Kitchell, J.P.; Nochur, S.V.

1991-05-16

The overall objective of this program was to investigate the feasibility of an enzymatic desulfurization process specifically intended for organic sulfur removal from coal. Toward that end, a series of specific objectives were defined: (1) establish the feasibility of (bio)oxidative pretreatment followed by biochemical sulfate cleavage for representative sulfur-containing model compounds and coals using commercially-available enzymes; (2) investigate the potential for the isolation and selective use of enzyme preparations from coal-utilizing microbial systems for desulfurization of sulfur-containing model compounds and coals; and (3) develop a conceptual design and economic analysis of a process for enzymatic removal of organic sulfur from coal. Within the scope of this program, it was proposed to carry out a portion of each of these efforts concurrently. (VC)

High throughput, high resolution enzymatic lithography process: effect of crystallite size, moisture, and enzyme concentration.

Science.gov (United States)

Mao, Zhantong; Ganesh, Manoj; Bucaro, Michael; Smolianski, Igor; Gross, Richard A; Lyons, Alan M

2014-12-08

By bringing enzymes into contact with predefined regions of a surface, a polymer film can be selectively degraded to form desired patterns that find a variety of applications in biotechnology and electronics. This so-called "enzymatic lithography" is an environmentally friendly process as it does not require actinic radiation or synthetic chemicals to develop the patterns. A significant challenge to using enzymatic lithography has been the need to restrict the mobility of the enzyme in order to maintain control of feature sizes. Previous approaches have resulted in low throughput and were limited to polymer films only a few nanometers thick. In this paper, we demonstrate an enzymatic lithography system based on Candida antartica lipase B (CALB) and poly(ε-caprolactone) (PCL) that can resolve fine-scale features, (<1 μm across) in thick (0.1-2.0 μm) polymer films. A Polymer Pen Lithography (PPL) tool was developed to deposit an aqueous solution of CALB onto a spin-cast PCL film. Immobilization of the enzyme on the polymer surface was monitored using fluorescence microscopy by labeling CALB with FITC. The crystallite size in the PCL films was systematically varied; small crystallites resulted in significantly faster etch rates (20 nm/min) and the ability to resolve smaller features (as fine as 1 μm). The effect of printing conditions and relative humidity during incubation is also presented. Patterns formed in the PCL film were transferred to an underlying copper foil demonstrating a "Green" approach to the fabrication of printed circuit boards.

Anaerobic degradation of linear alkylbenzene sulfonate

DEFF Research Database (Denmark)

Mogensen, Anders Skibsted; Haagensen, Frank; Ahring, Birgitte Kiær

2003-01-01

Linear alkylbenzene sulfonate (LAS) found in wastewater is removed in the wastewater treatment facilities by sorption and aerobic biodegradation. The anaerobic digestion of sewage sludge has not been shown to contribute to the removal. The concentration of LAS based on dry matter typically...... increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C...

DEGRADATION OF CZECHOSLOVAK CREEP RESISTANT STEELS AFTER 50 YEARS OF SERVICE

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Ladislav Horváth

2014-04-01

Full Text Available Thermally loaded assemblies in the energy and chemical industries require materials that provide the necessary functional characteristics, even after very long periods of operation. For the assessment of these materials are used expression grade of degradation in the basic meaning of the original English word grade = quality grade, Where the degradation is cumulative deterioration of quality (properties and thereby reduce the utility value. Knowledge of these mechanisms acting simultaneously allows determining the boundary conditions and more efficient utilization of used materials. Alternatively, it may give information to a qualified estimate of the causes of failure. Degradation starts its own production of semi-finished products (purity, structural homogeneity continues through technological factors of production (welding and the last part of degradation is during service of the parts (corrosion, hydrogen embrittlement, etc.. The aim of this article is at bases information obtained from fifty years of degraded materials to obtain information for more accurate reference catalogue. This catalogue can on bases information obtained from the microstructure and hardness estimate the state of degradation or possible time to rupture for the material.

Non-enzymatic antioxidant accumulations in BR-deficient and BR-insensitive barley mutants under control and drought conditions.

Science.gov (United States)

Gruszka, Damian; Janeczko, Anna; Dziurka, Michal; Pociecha, Ewa; Fodor, Jozsef

2017-12-07

Drought is one of the most adverse stresses that affect plant growth and yield. Disturbances in metabolic activity resulting from drought cause overproduction of reactive oxygen species. It is postulated that brassinosteroids (BRs) regulate plant tolerance to the stress conditions, but the underlying mechanisms remain largely unknown. An involvement of endogenous BRs in regulation of the antioxidant homeostasis is not fully clarified either. Therefore, the aim of this study was to elucidate the role of endogenous BRs in regulation of non-enzymatic antioxidants in barley (Hordeum vulgare) under control and drought conditions. The plant material included the 'Bowman' cultivar and a group of semi-dwarf near-isogenic lines (NILs), representing mutants deficient in BR biosynthesis or signaling. In general, accumulations of 11 compounds representing various types of non-enzymatic antioxidants were analyzed under both conditions. The analyses of accumulations of reduced and oxidized forms of ascorbate indicated that the BR mutants contain significantly higher contents of dehydroascorbic acid under drought conditions when compared with the 'Bowman' cultivar. The analysis of glutathione accumulation indicated that under the control conditions the BR-insensitive NILs contained significantly lower concentrations of this antioxidant when compared with the rest of genotypes. Therefore, we postulate that BR sensitivity is required for normal accumulation of glutathione. A complete accumulation profile of various tocopherols indicated that functional BR biosynthesis and signaling are required for their normal accumulation under both conditions. Results of this study provided an insight into the role of endogenous BRs in regulation of the non-enzymatic antioxidant homeostasis. © 2017 Scandinavian Plant Physiology Society.

Effects of thermal and enzymatic treatments and harvesting time on the microbial quality and chemical composition of fibre hemp (Cannabis sativa L.)

DEFF Research Database (Denmark)

Nykter, M.; Kymalainen, H.R.; Thomsen, Anne Belinda

2008-01-01

The aim of the present study was to examine the effects of pectinase enzyme treatment followed by thermal treatments (steam explosion and dry heating) on the microbial quality and chemical composition of hemp fibres. Before these treatments, the fibres were separated manually from the stems...... materials. Dry heating had no effect on mould and bacterial counts at temperatures below 120 degrees C and durations less than 60 min. The chemical composition was affected by the enzymatic treatment due to extraction and degradation of water-soluble components, pectin and ash. Thus the cellulose content...... increased by 6% w/w to 67-70% w/w. Steam explosion of the untreated hemp fibres increased the cellulose content to 74% w/w, whereas steam explosion of enzymatically treated hemp increased the cellulose content to 78% w/w. (c) 2007 Elsevier Ltd. All rights reserved....

Enzymatic Browning: a practical class

Directory of Open Access Journals (Sweden)

Maria Teresa Pedrosa Silva Clerici

2014-10-01

Full Text Available This paper presents a practical class about the enzymes polyphenol oxidases, which have been shown to be responsible for the enzymatic browning of fruits and vegetables. Vegetables samples were submitted to enzymatic inactivation process with chemical reagents, as well as by bleaching methods of applying heat by conventional oven and microwave oven. Process efficiency was assessed qualitatively by both observing the guaiacol peroxidase activity and after the storage period under refrigeration or freezing. The practical results obtained in this class allow exploring multidisciplinary knowledge in food science, with practical applications in everyday life.

An unprecedented extended architecture constructed from a 2-D interpenetrating cationic coordination framework templated by SiW12O404- anion

International Nuclear Information System (INIS)

Wang Xiuli; Lin Hongyan; Bi Yanfeng; Chen Baokuan; Liu Guocheng

2008-01-01

A novel inorganic-organic hybrid compound based on polyoxometalates (POMs) and organic ligand formulated as [Cu 2 (bpp) 4 (H 2 O) 2 ](SiW 12 O 40 )∼6H 2 O (1) [bpp=1,3-bis(4-pyridyl)propane], was hydrothermally synthesized and structurally characterized by elemental analysis, single-crystal X-ray diffraction analysis, IR, TG, and cyclic voltammetry. Crystal data for 1: Orthorhombic, Pbcn, a=23.0085(19) A, b=14.6379(12) A, c=23.6226(19) A, V=7956.0(11) A 3 , Z=4, Dc=3.315 g cm -3 , and R(final)=0.0826. X-ray diffraction study reveals that compound 1 was the first interpenetrating network of 2-D metal-organic cationic coordination framework [Cu 2 (bpp) 4 (H 2 O) 2 ] n 4n+ , in which Keggin-type anions SiW 12 O 40 4- has been used as a non-coordinating anionic template. The electrochemical property of 1-bulk modified carbon paste electrode (1-CPE) has been studied, and the results indicate that 1-CPE has good electrocatalytic activities toward the reduction of nitrite in 1 M H 2 SO 4 aqueous solution. - Graphical abstract: Compound [Cu 2 (bpp) 4 (H 2 O) 2 ](SiW 12 O 40 )∼6H 2 O (1) represents the first 2-D interpenetrating cationic metal-organic frameworks (MOFs) templated by Keggin-type anions. These MOF layers are stacked together along the crystallographic c axis exactly to construct large cubic-like channels (with dimensions of 12.3x13.6 A) occupied by SiW 12 O 40 4- clusters

Enzymatic biodiesel production: Technical and economical considerations

DEFF Research Database (Denmark)

Munk Nielsen, Per; Brask, Jesper; Fjerbæk, Lene

2008-01-01

It is well documented in the literature that enzymatic processing of oils and fats for biodiesel is technically feasible. However, with very few exceptions, enzyme technology is not currently used in commercial-scale biodiesel production. This is mainly due to non-optimized process design...... and a lack of available costeffective enzymes. The technology to re-use enzymes has typically proven insufficient for the processes to be competitive. However, literature data documenting the productivity of enzymatic biodiesel together with the development of new immobilization technology indicates...... that enzyme catalysts can become cost effective compared to chemical processing. This work reviews the enzymatic processing of oils and fats into biodiesel with focus on process design and economy....

Enzyme-driven Bacillus spore coat degradation leading to spore killing.

Science.gov (United States)

Mundra, Ruchir V; Mehta, Krunal K; Wu, Xia; Paskaleva, Elena E; Kane, Ravi S; Dordick, Jonathan S

2014-04-01

The bacillus spore coat confers chemical and biological resistance, thereby protecting the core from harsh environments. The primarily protein-based coat consists of recalcitrant protein crosslinks that endow the coat with such functional protection. Proteases are present in the spore coat, which play a putative role in coat degradation in the environment. However these enzymes are poorly characterized. Nonetheless given the potential for proteases to catalyze coat degradation, we screened 10 commercially available proteases for their ability to degrade the spore coats of B. cereus and B. anthracis. Proteinase K and subtilisin Carlsberg, for B. cereus and B. anthracis spore coats, respectively, led to a morphological change in the otherwise impregnable coat structure, increasing coat permeability towards cortex lytic enzymes such as lysozyme and SleB, thereby initiating germination. Specifically in the presence of lysozyme, proteinase K resulted in 14-fold faster enzyme induced germination and exhibited significantly shorter lag times, than spores without protease pretreatment. Furthermore, the germinated spores were shown to be vulnerable to a lytic enzyme (PlyPH) resulting in effective spore killing. The spore surface in response to proteolytic degradation was probed using scanning electron microscopy (SEM), which provided key insights regarding coat degradation. The extent of coat degradation and spore killing using this enzyme-based pretreatment approach is similar to traditional, yet far harsher, chemical decoating methods that employ detergents and strong denaturants. Thus the enzymatic route reduces the environmental burden of chemically mediated spore killing, and demonstrates that a mild and environmentally benign biocatalytic spore killing is achievable. © 2013 Wiley Periodicals, Inc.

Enzymatic solubilisation and degradation of soybean fibre demonstrated by viscosity, fibre analysis and microscopy

DEFF Research Database (Denmark)

Ravn, Jonas Laukkonen; Martens, Helle Juel; Pettersson, Dan

2015-01-01

The effect of a commercial multienzyme product obtained by fermentation from Aspergillus aculeatus on soybean and soybean meal was investigated using viscosity measurements, dietary fibre component analysis and different microscopy techniques utilizing histochemical dyes and antibody labelling....... The results obtained demonstrated a strong viscosity reducing effect of the enzyme preparation on soluble galactomannan and xyloglucan polysaccharides and in addition non-starch polysaccharide analysis demonstrated a notable solubilisation of all polysaccharide constituents. The degradation...

Temporal changes in wood crystalline cellulose during degradation by brown rot fungi

DEFF Research Database (Denmark)

Howell, Caitlin; Hastrup, Anne Christine Steenkjær; Goodell, Barry

2009-01-01

The degradation of wood by brown rot fungi has been studied intensely for many years in order to facilitate the preservation of in-service wood. In this work we used X-ray diffraction to examine changes in wood cellulose crystallinity caused by the brown rot fungi Gloeophyllum trabeum, Coniophora...... planes in all degraded samples after roughly 20% weight loss, as well as a decrease in the average observed relative peak width at 2¿ = 22.2°. These results may indicate a disruption of the outer most semi-crystalline cellulose chains comprising the wood microfibril. X-ray diffraction analysis of wood...... subjected to biological attack by fungi may provide insight into degradative processes and wood cellulose structure....

Photovoltaic Properties in Interpenetrating Heterojunction Organic Solar Cells Utilizing MoO3 and ZnO Charge Transport Buffer Layers

Science.gov (United States)

Hori, Tetsuro; Moritou, Hiroki; Fukuoka, Naoki; Sakamoto, Junki; Fujii, Akihiko; Ozaki, Masanori

2010-01-01

Organic thin-film solar cells with a conducting polymer (CP)/fullerene (C60) interpenetrating heterojunction structure, fabricated by spin-coating a CP onto a C60 deposit thin film, have been investigated and demonstrated to have high efficiency. The photovoltaic properties of solar cells with a structure of indium-tin-oxide/C60/poly(3-hexylthiophene) (PAT6)/Au have been improved by the insertion of molybdenum trioxide (VI) (MoO3) and zinc oxide charge transport buffer layers. The enhanced photovoltaic properties have been discussed, taking into consideration the ground-state charge transfer between PAT6 and MoO3 by measurement of the differential absorption spectra and the suppressed contact resistance at the interface between the organic and buffer layers. PMID:28883360

Photovoltaic Properties in Interpenetrating Heterojunction Organic Solar Cells Utilizing MoO3 and ZnO Charge Transport Buffer Layers

Directory of Open Access Journals (Sweden)

Tetsuro Hori

2010-11-01

Full Text Available Organic thin-film solar cells with a conducting polymer (CP/fullerene (C60 interpenetrating heterojunction structure, fabricated by spin-coating a CP onto a C60 deposit thin film, have been investigated and demonstrated to have high efficiency. The photovoltaic properties of solar cells with a structure of indium-tin-oxide/C60/ poly(3-hexylthiophene (PAT6/Au have been improved by the insertion of molybdenum trioxide (VI (MoO3 and zinc oxide charge transport buffer layers. The enhanced photovoltaic properties have been discussed, taking into consideration the ground-state charge transfer between PAT6 and MoO3 by measurement of the differential absorption spectra and the suppressed contact resistance at the interface between the organic and buffer layers.

'If only it would rain': Farmers' perceptions of rainfall and drought in semi-arid central Tanzania

NARCIS (Netherlands)

Slegers, M.F.W.

2008-01-01

Farmers in semi-arid East Africa prioritize drought as their major productivity-reducing problem, while scientists identify soil degradation as a major threat. The question that needs to be addressed is how farmers perceive drought. Insight into farmers¿ perceptions of drought could be the missing

Alkali-aided enzymatic viscosity reduction of sugar beet mash for novel bioethanol production process

International Nuclear Information System (INIS)

Srichuwong, Sathaporn; Arakane, Mitsuhiro; Fujiwara, Maki; Zhang, Zilian; Takahashi, Hiroyuki; Tokuyasu, Ken

2010-01-01

Ethanol fermentation of fresh sugar beet mash (SBM) could give a benefit on reducing energy input for sugar diffusion, juice separation, and water evaporation as used in conventional practices, thus offering promise as a low energy process. Actions of cell-wall degrading enzymes provide a mash with low viscosity, which can be easily fermented to ethanol. However, a several-fold higher enzyme loading was required for viscosity reduction of SBM compared with that of potato mash. In this study, the use of dilute alkali treatment (0.025-0.15 N NaOH, 25 o C, 1 h) in enhancing enzymatic viscosity reduction of SBM was evaluated. The results showed that higher NaOH concentration enhanced demethylation and deacetylation of SBM, resulting in greater performances of the enzymes on reducing viscosity. Efficient enzymatic viscosity reduction of SBM was observed with the 0.1 N NaOH treatment. On the other hand, untreated SBM was highly resistant to viscosity reduction, even though a 20-fold more enzyme loading was used. The resulting mash containing 12-13% (w/v) sucrose yielded 7-8% (v/v) ethanol after 24 h of fermentation (90% efficiency). Accordingly, alkali treatment can be applied for facilitating the use of fresh sugar beet for ethanol production.

Physical properties of a high molecular weight hydroxyl-terminated polydimethylsiloxane modified castor oil based polyurethane/epoxy interpenetrating polymer network composites

Science.gov (United States)

Chen, Shoubing; Wang, Qihua; Wang, Tingmei

2011-06-01

A series of polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites modified by a high molecular weight hydroxyl-terminated polydimethylsiloxane (HTPDMS) were prepared. The effects of HTPDMS content on the phase structure, damping properties and the glass transition temperature ( Tg) of the HTPDMS-modified PU/EP IPN composites were studied by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). Thermogravimetric analysis (TGA) showed that the thermal decomposition temperature of the composites increased with the increase of HTPDMS content. The tensile strength and impact strength of the IPN composites were also significantly improved, especially when the HTPDMS content was 10%. The modified IPN composites were expected to be used as structural damping materials in the future.

Biosensing strategies based on enzymatic reactions and nanoparticles.

Science.gov (United States)

Díez-Buitrago, Beatriz; Briz, Nerea; Liz-Marzán, Luis M; Pavlov, Valeri

2018-04-16

Enzymes are pivotal elements in bioanalysis due to their specificity and extremely high catalytic activity. The sensitivity of bioanalytical assays depends mainly on the capacity of an observer to detect the product(s) of a biocatalytic reaction. Both natural and artificial compounds have been traditionally used to evaluate enzymatic activities. The drawbacks of chromogenic and fluorogenic organic enzymatic substrates are their high cost and low stability, resulting in high background signals. We review here state of the art assays in the detection of enzymatic activities using recent advances in nanoscience. Novel methods based on the use of nanoparticles lead to increased sensitivity and decreased costs for bioanalysis based on enzymes as recognition elements and signal amplifiers in Enzyme-Linked Immunosorbent Assays (ELISA). Novel approaches toward the detection of enzymatic activities are based on biocatalytic synthesis, modulation, etching, and aggregation of nanoparticles under physiological conditions.

Screening a strain of Aspergillus niger and optimization of fermentation conditions for degradation of aflatoxin B₁.

Science.gov (United States)

Zhang, Wei; Xue, Beibei; Li, Mengmeng; Mu, Yang; Chen, Zhihui; Li, Jianping; Shan, Anshan

2014-11-13

Aflatoxin B₁, a type of highly toxic mycotoxin produced by some species belonging to the Aspergillus genus, such as Aspergillus flavus and Aspergillus parasiticus, is widely distributed in feed matrices. Here, coumarin was used as the sole carbon source to screen microorganism strains that were isolated from types of feed ingredients. Only one isolate (ND-1) was able to degrade aflatoxin B₁ after screening. ND-1 isolate, identified as a strain of Aspergillus niger using phylogenetic analysis on the basis of 18S rDNA, could remove 26.3% of aflatoxin B₁ after 48 h of fermentation in nutrient broth (NB). Optimization of fermentation conditions for aflatoxin B₁ degradation by selected Aspergillus niger was also performed. These results showed that 58.2% of aflatoxin B₁ was degraded after 24 h of culture under the optimal fermentation conditions. The aflatoxin B₁ degradation activity of Aspergillus niger supernatant was significantly stronger than cells and cell extracts. Furthermore, effects of temperature, heat treatment, pH, and metal ions on aflatoxin B₁ degradation by the supernatant were examined. Results indicated that aflatoxin B₁ degradation of Aspergillus niger is enzymatic and this process occurs in the extracellular environment.

Enzymatic Inverse Opal Hydrogel Particles for Biocatalyst.

Science.gov (United States)

Wang, Huan; Gu, Hongcheng; Chen, Zhuoyue; Shang, Luoran; Zhao, Ze; Gu, Zhongze; Zhao, Yuanjin

2017-04-19

Enzymatic carriers have a demonstrated value for chemical reactions and industrial applications. Here, we present a novel kind of inverse opal hydrogel particles as the enzymatic carriers. The particles were negatively replicated from spherical colloidal crystal templates by using magnetic nanoparticles tagged acrylamide hydrogel. Thus, they were endowed with the features of monodispersity, small volume, complete penetrating structure, and controllable motion, which are all beneficial for improving the efficiency of biocatalysis. In addition, due to the ordered porous nanostructure, the inverse opal hydrogel particles were imparted with unique photonic band gaps (PBGs) and vivid structural colors for encoding varieties of immobilized enzymes and for constructing a multienzymes biocatalysis system. These features of the inverse opal hydrogel particles indicate that they are ideal enzymatic carriers for biocatalysis.

Extractability and digestibility of plant cell wall polysaccharides during hydrothermal and enzymatic degradation of wheat straw (Triticum aestivum L.)

DEFF Research Database (Denmark)

Hansen, Mads A.T.; Ahl, Louise I.; Pedersen, Henriette L.

2014-01-01

to about 20, but mostly around 3-8, and notably more acetylated in stems. Arabinoxylan (AX) and mixed-linkage glucan (MLG) became water-extractable while xylan, xyloglucan (XG), mannan and glucan remained only alkali-extractable. All polysaccharides became partly digestible after pretreatment however......, regardless their extractability in water or only alkali. Based on the results, AX and MLG appear to be loosely bound in the cell wall matrix while the other polysaccharides are bound more tightly and shielded from enzymatic attack by AX and MLG until pretreatment. The gradual solubilisation and digestion...

Enzymatic Processes in Marine Biotechnology.

Science.gov (United States)

Trincone, Antonio

2017-03-25

In previous review articles the attention of the biocatalytically oriented scientific community towards the marine environment as a source of biocatalysts focused on the habitat-related properties of marine enzymes. Updates have already appeared in the literature, including marine examples of oxidoreductases, hydrolases, transferases, isomerases, ligases, and lyases ready for food and pharmaceutical applications. Here a new approach for searching the literature and presenting a more refined analysis is adopted with respect to previous surveys, centering the attention on the enzymatic process rather than on a single novel activity. Fields of applications are easily individuated: (i) the biorefinery value-chain, where the provision of biomass is one of the most important aspects, with aquaculture as the prominent sector; (ii) the food industry, where the interest in the marine domain is similarly developed to deal with the enzymatic procedures adopted in food manipulation; (iii) the selective and easy extraction/modification of structurally complex marine molecules, where enzymatic treatments are a recognized tool to improve efficiency and selectivity; and (iv) marine biomarkers and derived applications (bioremediation) in pollution monitoring are also included in that these studies could be of high significance for the appreciation of marine bioprocesses.

[Screening of harmine tolerance/degrading bacteria from camel rumen].

Science.gov (United States)

An, Dengdi; Zhu, Yanlei; Tang, Jing; Ye, Yongxia; Zeng, Xianchun

2010-08-01

Peganum harmala, a famous traditional Chinese drug, contains a variety of alkaloids and toxic for many animals. Camels mainly live in desert or semi-desert areas, with the robust gastrointestine system in digesting various feed including toxic plants without disease symptoms. Camel rumen content was used as the inoculant to inoculate medium M98-5 which contains 100 mg x L(-1) harmin and cultivated for 5 days. Upto 5 subculturings, strains that could degrading or tolerant harmine were isolated. Their conversion activity was determined by thin-layer chromatography. The taxonomic position of the strains were identified based on 16S rRNA sequences analysis. 15 out of the 29 isolates have harmine degrading activity. Most of the isolates are identified as the members of the Genera Lactobacillus (16 strains, 55%), Shigella (7 strains, 24%) and Bacillus (4 strains, 13.8%). Only one strain belong to genus Enterococcus and one belong to genus Megasphaera. The results indicated that the harmine tolerance/degrading communities of camel rumen are limited and only Lactobacillus have harmine-degrading activity.

Photonic shape memory polymer with stable multiple colors

NARCIS (Netherlands)

Moirangthem, M.; Engels, T.A.P.; Murphy, J.; Bastiaansen, C.W.M.; Schenning, A.P.H.J.

2017-01-01

A photonic shape memory polymer film that shows large color response (∼155 nm) in a wide temperature range has been fabricated from a semi-interpenetrating network of a cholesteric polymer and poly(benzyl acrylate). The large color response is achieved by mechanical embossing of the photonic film

Phenotypic and chemotypic characterization of GABA-shunt mutants in Arabidopsis thaliana

OpenAIRE

Mekonnen, Dereje Worku

2013-01-01

Gamma-Aminobutyric acid (GABA) is a four carbon non protein amino acid, and the pathway that involves its production and degradation is called the GABA shunt. The GABA shunt is a short enzymatic pathway that involves three enzymes: glutamate decarboxylase (GAD), GABA transaminase (GABA-T) and succinic semi aldehyde dehydrogenase (SSADH). GABA shunt is conserved almost in all organisms studied so far. The pathway starts in the cytosol and finishes in mitochondria in higher organisms like plant...

Effects of thermal and enzymatic treatments and harvesting time on the microbial quality and chemical composition of fibre hemp (Cannabis sativa L.)

Energy Technology Data Exchange (ETDEWEB)

Nykter, Minna; Kymaelaeinen, Hanna-Riitta; Sjoeberg, Anna-Maija [Department of Agrotechnology, University of Helsinki, P.O. Box 28, FI-00014 University of Helsinki (Finland); Thomsen, Anne Belinda; Thygesen, Anders [Biosystems Department, Risoe National Laboratory, P.O. Box 49, DK-4000 Roskilde (Denmark); Lilholt, Hans [Materials Research Department, Risoe National Laboratory, P.O. Box 49, DK-4000 Roskilde (Denmark); Koponen, Hilkka [Department of Applied Biology, Section of Plant Pathology, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki (Finland)

2008-05-15

The aim of the present study was to examine the effects of pectinase enzyme treatment followed by thermal treatments (steam explosion and dry heating) on the microbial quality and chemical composition of hemp fibres. Before these treatments, the fibres were separated manually from the stems harvested after stand retting in the field before frost, after early frost or in the following spring. The enzymatic treatment of hemp promoted growth of moulds on the fibres (500-fold increase in colony-forming units (cfu)), whereas steam explosion reduced the amount of moulds to a relatively constant level of 10{sup 2} cfu/g dw. The amount of bacteria was not markedly affected by enzymatic treatment but was reduced tenfold after steam explosion. Steam explosion is thereby a potentially good process for the production of hemp fibres with low fungal contamination, which can be of importance in insulation materials. Dry heating had no effect on mould and bacterial counts at temperatures below 120 C and durations less than 60 min. The chemical composition was affected by the enzymatic treatment due to extraction and degradation of water-soluble components, pectin and ash. Thus the cellulose content increased by 6% w/w to 67-70% w/w. Steam explosion of the untreated hemp fibres increased the cellulose content to 74% w/w, whereas steam explosion of enzymatically treated hemp increased the cellulose content to 78% w/w. (author)

Enzymatic and acidic degradation of high molecular weight dextran into low molecular weight and its characterizations using novel Diffusion-ordered NMR spectroscopy.

Science.gov (United States)

Iqbal, Samina; Marchetti, Roberta; Aman, Afsheen; Silipo, Alba; Qader, Shah Ali Ul; Molinaro, Antonio

2017-10-01

Low molecular weight fractions were derived from native high molecular weight dextran produced by Leuconostoc mesenteroides KIBGE-IB26. Structural characterization of native and low molecular weight fractions obtained after acidic and enzymatic hydrolysis was done using FTIR and NMR spectroscopy. The molecular weight was estimated using Diffusion Ordered NMR spectroscopy. Native dextran (892kDa) is composed of α-(1→6) glycosidic linkage along with α-(1→3) branching. Major proportion of 528kDa dextran was obtained after prolong enzymatic hydrolysis however, an effective acidic treatment at pH-1.4 up to 02 and 04h of exposure resulted in the formation of 77kDa and 57kDa, respectively. The increment in pH from 1.4 to 1.8 lowered the hydrolysis efficiency and resulted in the formation of 270kDa dextran fraction. The results suggest that derived low molecular weight water soluble fractions can be utilized as a drug delivery carrier along with multiple application relating pharmaceutical industries. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhancement of Cellulose Degradation by Cattle Saliva

Science.gov (United States)

Seki, Yasutaka; Kikuchi, Yukiko; Kimura, Yoshihiro; Yoshimoto, Ryo; Takahashi, Masatoshi; Aburai, Kenichi; Kanai, Yoshihiro; Ruike, Tatsushi; Iwabata, Kazuki; Sugawara, Fumio; Sakai, Hideki; Abe, Masahiko; Sakaguchi, Kengo

2015-01-01

Saccharification of cellulose is a promising technique for producing alternative source of energy. However, the efficiency of conversion of cellulose into soluble sugar using any currently available methodology is too low for industrial application. Many additives, such as surfactants, have been shown to enhance the efficiency of cellulose-to-sugar conversion. In this study, we have examined first whether cattle saliva, as an additive, would enhance the cellulase-catalyzed hydrolysis of cellulose, and subsequently elucidated the mechanism by which cattle saliva enhanced this conversion. Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose. Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva. We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect. Third, the mechanism of cattle saliva mediated enhancement of cellulase activity was probably similar to that of the canonical surfactants. Cattle saliva is available in large amounts easily and cheaply, and it can be used without further purification. Thus, cattle saliva could be a promising additive for efficient saccharification of cellulose on an industrial scale. PMID:26402242

Insights into the degradation of human elastin by matrilysin-1

DEFF Research Database (Denmark)

Heinz, Andrea; Taddese, Samuel; Sippl, Wolfgang

2011-01-01

Human matrilysin-1 (MMP-7) is one of the most potent elastases besides macrophage elastase in the family of matrix metalloproteinases (MMPs). It has been reported to provide macrophages with the highest elastinolytic capacity and plays key roles in diseases such as emphysema and cancer. Describin...... into the degradation of human elastin by MMP-7 and may aid in the development of approaches to treat elastin-degrading diseases.......Human matrilysin-1 (MMP-7) is one of the most potent elastases besides macrophage elastase in the family of matrix metalloproteinases (MMPs). It has been reported to provide macrophages with the highest elastinolytic capacity and plays key roles in diseases such as emphysema and cancer. Describing...... the enzymatic turnover of matrix components helps to understand the molecular basis of disease processes. Hence, in this work, the cleavage behavior of MMP-7 with respect to its natural substrate human elastin was investigated using mass spectrometric (MS) techniques and molecular modeling. Elastin peptides...

Microbial surface displayed enzymes based biofuel cell utilizing degradation products of lignocellulosic biomass for direct electrical energy.

Science.gov (United States)

Fan, Shuqin; Hou, Chuantao; Liang, Bo; Feng, Ruirui; Liu, Aihua

2015-09-01

In this work, a bacterial surface displaying enzyme based two-compartment biofuel cell for the direct electrical energy conversion from degradation products of lignocellulosic biomass is reported. Considering that the main degradation products of the lignocellulose are glucose and xylose, xylose dehydrogenase (XDH) displayed bacteria (XDH-bacteria) and glucose dehydrogenase (GDH) displayed bacteria (GDH-bacteria) were used as anode catalysts in anode chamber with methylene blue as electron transfer mediator. While the cathode chamber was constructed with laccase/multi-walled-carbon nanotube/glassy-carbon-electrode. XDH-bacteria exhibited 1.75 times higher catalytic efficiency than GDH-bacteria. This assembled enzymatic fuel cell exhibited a high open-circuit potential of 0.80 V, acceptable stability and energy conversion efficiency. Moreover, the maximum power density of the cell could reach 53 μW cm(-2) when fueled with degradation products of corn stalk. Thus, this finding holds great potential to directly convert degradation products of biomass into electrical energy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Winery biomass waste degradation by sequential sonication and mixed fungal enzyme treatments.

Science.gov (United States)

Karpe, Avinash V; Dhamale, Vijay V; Morrison, Paul D; Beale, David J; Harding, Ian H; Palombo, Enzo A

2017-05-01

To increase the efficiency of winery-derived biomass biodegradation, grape pomace was ultrasonicated for 20min in the presence of 0.25M, 0.5Mand1.0MKOH and 1.0MNaOH. This was followed by treatment with a 1:1 (v/v) mix of crude enzyme preparation derived from Phanerochaete chrysosporium and Trametes versicolor for 18h and a further 18h treatment with a 60:14:4:2 percent ratio combination of enzymes derived from Aspergillus niger: Penicillium chrysogenum: Trichoderma harzianum: P. citrinum, repsectively. Process efficiency was evaluated by its comparison to biological only mixed fungal degradation over 16days. Ultrasonication treatment with 0.5MKOH followed by mixed enzyme treatment yielded the highest lignin degradation of about 13%. Cellulase, β-glucosidase, xylanase, laccase and lignin peroxidase activities of 77.9, 476, 5,390.5, 66.7 and 29,230.7U/mL, respectively, were observed during biomass degradation. Gas chromatography-mass spectrometry (GC-MS) analysis of the degraded material identified commercially important compounds such as gallic acid, lithocholic acid, glycolic acid and lactic acid which were generated in considerable quantities. Thus, the combination of sonication pre-treatment and enzymatic degradation has the potential to considerably improve the breakdown of agricultural biomass and produce commercially useful compounds in markedly less time (<40h) with respect to biological only degradation (16days). Copyright © 2016 Elsevier Inc. All rights reserved.

Microbial dynamics in anaerobic enrichment cultures degrading di-n-butyl phthalic acid ester

DEFF Research Database (Denmark)

Trably, Eric; Batstone, Damien J.; Christensen, Nina

2008-01-01

losses were observed in the sterile controls (20-22%), substantial DBP biodegradation was found in the enrichment cultures (90-99%). In addition, significant population changes were observed. The dominant bacterial species in the DBP-degrading cultures was affiliated to Soehngenia saccharolytica...... in enrichment cultures degrading phthalic acid esters under methanogenic conditions. A selection pressure was applied by adding DBP at 10 and 200 mg L(-1) in semi-continuous anaerobic reactors. The microbial dynamics were monitored using single strand conformation polymorphism (SSCP). While only limited abiotic...

Enzymatic Synthesis of Psilocybin.

Science.gov (United States)

Fricke, Janis; Blei, Felix; Hoffmeister, Dirk

2017-09-25

Psilocybin is the psychotropic tryptamine-derived natural product of Psilocybe carpophores, the so-called "magic mushrooms". Although its structure has been known for 60 years, the enzymatic basis of its biosynthesis has remained obscure. We characterized four psilocybin biosynthesis enzymes, namely i) PsiD, which represents a new class of fungal l-tryptophan decarboxylases, ii) PsiK, which catalyzes the phosphotransfer step, iii) the methyltransferase PsiM, catalyzing iterative N-methyl transfer as the terminal biosynthetic step, and iv) PsiH, a monooxygenase. In a combined PsiD/PsiK/PsiM reaction, psilocybin was synthesized enzymatically in a step-economic route from 4-hydroxy-l-tryptophan. Given the renewed pharmaceutical interest in psilocybin, our results may lay the foundation for its biotechnological production. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Degradation analysis and modeling of reinforced catalyst coated membranes operated under OCV conditions

Energy Technology Data Exchange (ETDEWEB)

Kundu, Sumit; Fowler, Michael W.; Simon, Leonardo C. [Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario (Canada); Abouatallah, Rami; Beydokhti, Natasha [Hydrogenics Corporation, 5985 McLaughlin Road, Mississauga, Ontario (Canada)

2008-09-01

This paper studies the degradation of Gore trademark PRIMEA {sup registered} series 5510 catalyst coated membranes with an ePTFE reinforcement layer under open circuit voltage conditions at 90 C, 75% RH, and no backpressure. Scanning electron microscopy (SEM) imaging of cross-sections revealed extensive cathode-side ionomer degradation and the presence of a platinum band. Cumulative fluoride release measurements show more fluoride exiting with the cathode effluent. Furthermore, both anode and cathode cumulative fluoride release plateau after long degradation times. Open circuit voltage was also monitored and the degradation rate was found to decrease after a long duration. It is proposed that all fluoride species are generated from the cathode-side ionomer degradation process and that the fluoride then diffuses to the anode and cathode channels. Further, once the cathode-side ionomer is consumed the degradation reaction slows as the ''degradation front'' passes through the inert reinforcement layer. This process was modeled using a semi-empirical transient model and compared to experimental results. (author)

Nucleases from Prevotella intermedia can degrade neutrophil extracellular traps.

Science.gov (United States)

Doke, M; Fukamachi, H; Morisaki, H; Arimoto, T; Kataoka, H; Kuwata, H

2017-08-01

Periodontitis is an inflammatory disease caused by periodontal bacteria in subgingival plaque. These bacteria are able to colonize the periodontal region by evading the host immune response. Neutrophils, the host's first line of defense against infection, use various strategies to kill invading pathogens, including neutrophil extracellular traps (NETs). These are extracellular net-like fibers comprising DNA and antimicrobial components such as histones, LL-37, defensins, myeloperoxidase, and neutrophil elastase from neutrophils that disarm and kill bacteria extracellularly. Bacterial nuclease degrades the NETs to escape NET killing. It has now been shown that extracellular nucleases enable bacteria to evade this host antimicrobial mechanism, leading to increased pathogenicity. Here, we compared the DNA degradation activity of major Gram-negative periodontopathogenic bacteria, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans. We found that Pr. intermedia showed the highest DNA degradation activity. A genome search of Pr. intermedia revealed the presence of two genes, nucA and nucD, putatively encoding secreted nucleases, although their enzymatic and biological activities are unknown. We cloned nucA- and nucD-encoding nucleases from Pr. intermedia ATCC 25611 and characterized their gene products. Recombinant NucA and NucD digested DNA and RNA, which required both Mg 2+ and Ca 2+ for optimal activity. In addition, NucA and NucD were able to degrade the DNA matrix comprising NETs. © 2016 The Authors Molecular Oral Microbiology Published by John Wiley & Sons Ltd.

Operation and Control of Enzymatic Biodiesel Production

DEFF Research Database (Denmark)

Price, Jason Anthony; Huusom, Jakob Kjøbsted; Nordblad, Mathias

This work explores the control of biodiesel production via an enzymatic catalyst. The process involves the transesterification of oils/fats with an alcohol (usually methanol or ethanol), using enzymatic catalysts to generate mono-alkyl esters (the basis of biodiesel) and glycerol as by......-product. Current literature indicates that enzymatic processing of oils and fats to produce biodiesel is technically feasible and developments in immobilization technology indicate that enzyme catalysts can become cost effective compared to chemical processing. However, with very few exceptions, enzyme technology...... is not currently used in commercial-scale biodiesel production. This is mainly due to non-optimized process designs, which do not use the full potential of the catalysts in a cost-efficient way. Furthermore is it unclear what process variables need to be monitored and controlled to ensure optimal economics...

A genetic bistable switch utilizing nonlinear protein degradation.

Science.gov (United States)

Huang, Daniel; Holtz, William J; Maharbiz, Michel M

2012-07-09

Bistability is a fundamental property in engineered and natural systems, conferring the ability to switch and retain states. Synthetic bistable switches in prokaryotes have mainly utilized transcriptional components in their construction. Using both transcriptional and enzymatic components, creating a hybrid system, allows for wider bistable parameter ranges in a circuit. In this paper, we demonstrate a tunable family of hybrid bistable switches in E. coli using both transcriptional components and an enzymatic component. The design contains two linked positive feedback loops. The first loop utilizes the lambda repressor, CI, and the second positive feedback loop incorporates the Lon protease found in Mesoplasma florum (mf-Lon). We experimentally tested for bistable behavior in exponential growth phase, and found that our hybrid bistable switch was able to retain its state in the absence of an input signal throughout 40 cycles of cell division. We also tested the transient behavior of our switch and found that switching speeds can be tuned by changing the expression rate of mf-Lon. To our knowledge, this work demonstrates the first use of dynamic expression of an orthogonal and heterologous protease to tune a nonlinear protein degradation circuit. The hybrid switch is potentially a more robust and tunable topology for use in prokaryotic systems.

Immobilization of enzymatic extracts of Portulaca oleracea cv. roots for oxidizing aqueous bisphenol A.

Science.gov (United States)

Matsushima, Kazuki; Kaneda, Hirokazu; Harada, Kazuo; Matsuura, Hideyuki; Hirata, Kazumasa

2015-05-01

Water pollution from the release of industrial wastewater is a serious problem for almost every industry. Enzymes from portulaca, Portulaca oleracea cv., have been investigated for their ability to degrade bisphenol A (BPA), one of the well-known estrogenic pollutants. Enzymatic crude extracts from P. oleracea cv. roots were immobilized on aminopropyl-modified glass beads. They maintained BPA metabolic activity over a broad range of pH values and temperatures. The immobilized enzyme was reusable with more than 50 % of its initial activity retained after 12 batch reactions and no loss of activity after storage for 1 month at -30 °C. Thus, the immobilization of extracts from P. oleracea cv. roots is a useful method for removing BPA from industrial wastewater.

Fracture initiation associated with chemical degradation: observation and modeling

Energy Technology Data Exchange (ETDEWEB)

Byoungho Choi; Zhenwen Zhou; Chudnovsky, Alexander [Illinois Univ., Dept. of Civil and Materials Engineering (M/C 246), Chicago, IL (United States); Stivala, Salvatore S. [Stevens Inst. of Technology, Dept. of Chemistry and Chemical Biology, Hoboken, NJ (United States); Sehanobish, Kalyan; Bosnyak, Clive P. [Dow Chemical Co., Freeport, TX (United States)

2005-01-01

The fracture initiation in engineering thermoplastics resulting from chemical degradation is usually observed in the form of a microcrack network within a surface layer of degraded polymer exposed to a combined action of mechanical stresses and chemically aggressive environment. Degradation of polymers is usually manifested in a reduction of molecular weight, increase of crystallinity in semi crystalline polymers, increase of material density, a subtle increase in yield strength, and a dramatic reduction in toughness. An increase in material density, i.e., shrinkage of the degraded layer is constrained by adjacent unchanged material results in a buildup of tensile stress within the degraded layer and compressive stress in the adjacent unchanged material due to increasing incompatibility between the two. These stresses are an addition to preexisting manufacturing and service stresses. At a certain level of degradation, a combination of toughness reduction and increase of tensile stress result in fracture initiation. A quantitative model of the described above processes is presented in these work. For specificity, the internally pressurized plastic pipes that transport a fluid containing a chemically aggressive (oxidizing) agent is used as the model of fracture initiation. Experimental observations of material density and toughness dependence on degradation reported elsewhere are employed in the model. An equation for determination of a critical level of degradation corresponding to the offset of fracture is constructed. The critical level of degradation for fracture initiation depends on the rates of toughness deterioration and build-up of the degradation related stresses as well as on the manufacturing and service stresses. A method for evaluation of the time interval prior to fracture initiation is also formulated. (Author)

Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse.

Science.gov (United States)

Agarwal, Vinayak; Miles, Zachary D; Winter, Jaclyn M; Eustáquio, Alessandra S; El Gamal, Abrahim A; Moore, Bradley S

2017-04-26

Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature's halogenation and dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.

Glucose obtained from rice bran by ultrasound-assisted enzymatic hydrolysis

Directory of Open Access Journals (Sweden)

Raquel Cristine Kuhn

2015-05-01

Full Text Available In this work ultrasound-assisted solid-state enzymatic hydrolysis of rice bran to obtain fermentable sugars was investigated. For this purpose, process variables such as temperature, enzyme concentration and moisture content were evaluated during the enzymatic hydrolysis with and without ultrasound irradiation. The enzyme used is a blend of amylases derived from genetically modified strains of Trichoderma reesei. Kinetic of the enzymatic hydrolysis of rice bran at the constant-reaction rate period were measured. The best results for the ultrasound-assisted enzymatic hydrolysis was obtained using 3 wt% of enzyme, 60 oC and moisture content of 65 wt%, yielding 0.38 g sugar/g rice bran, whereas for the hydrolysis in the absence of ultrasound the highest yield was 0.20 g sugar/g rice bran using 3 wt% of enzyme, 60 oC and moisture content of 50 wt%. The use of ultrasound-assisted enzymatic hydrolysis of rice bran was intensified, obtaining around 74% more fermentable sugar than in the absence, showing that the use of ultrasound is a promising technology to be used in enzymatic reaction as an alternative of process intensification.

Enzymatic hydrolysis of plant extracts containing inulin

Energy Technology Data Exchange (ETDEWEB)

Guiraud, J.P.; Galzy, P.

1981-10-01

Inulin-rich extracts of chicory and Jerusalem artichoke are a good potential source of fructose. Total enzymatic hydrolysis of these extracts can be effected by yeast inulinases (EC 3.2.1.7). Chemical prehydrolysis is unfavourable. Enzymatic hydrolysis has advantages over chemical hydrolysis: it does not produce a dark-coloured fraction or secondary substances. It is possible to envisage the preparation of high fructose syrups using this process. (Refs. 42).

Spectral mixture analysis (SMA and change vector analysis (CVA methods for monitoring and mapping land degradation/desertification in arid and semiarid areas (Sudan, using Landsat imagery

Directory of Open Access Journals (Sweden)

Abdelrahim A.M. Salih

2017-04-01

Full Text Available The severe Sahel catastrophe in 1968–1974 as well as repeated famines and food shortage that have hit many African countries during the 1970s have highlighted the need for further research concerning land degradation and environmental monitoring in arid and semi-arid areas. Land degradation, and desertification processes in arid and semi-arid environment were increased in the last four decades, especially in the developing countries like Sudan. To test to what extent remote sensing and geographical information science (GIS methodologies and techniques could be used for monitoring changes in arid and semi-arid regions and environment, these methodologies have long been suggested as a time and cost-efficient method. In this frame, spectral Mixture Analysis (SMA, Object-based oriented classification (Segmentation, and Change Vector Analysis are recently much recommended as a most suitable method for monitoring and mapping land cover changes in arid and semi-arid environment. Therefor the aim of this study is to use these methods and techniques for environmental monitoring with emphasis on desertification and to find model that can describe and map the status and rate of desertification processes and land cover changes in semi-arid areas in White Nile State (Sudan by using multi-temporal imagery of the Landsat satellite TM (1987, TM (2000, and ETM+ (2014 respectively. The paper also discusses and evaluates the efficiency of the adapted methodologies in monitoring the land degradation processes and changes in the arid and semi-arid regions.

2D→3D polycatenated and 3D→3D interpenetrated metal–organic frameworks constructed from thiophene-2,5-dicarboxylate and rigid bis(imidazole) ligands

Energy Technology Data Exchange (ETDEWEB)

Erer, Hakan [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Yeşilel, Okan Zafer, E-mail: yesilel@ogu.edu.tr [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Arıcı, Mürsel [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Keskin, Seda [Department of Chemical and Biological Engineering, Koç University, İstanbul (Turkey); Büyükgüngör, Orhan [Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Samsun (Turkey)

2014-02-15

Hydrothermal reactions of rigid 1,4-bis(imidazol-1-yl)benzene (dib) and 1,4-bis(imidazol-1-yl)-2,5-dimethylbenzene (dimb) with deprotonated thiophene-2,5-dicarboxylic acid (H{sub 2}tdc) in the presence of Zn(II) and Cd(II) salts in H{sub 2}O produced three new metal–organic frameworks, namely, [Zn(µ-tdc)(H{sub 2}O)(µ-dib)]{sub n} (1), [Cd(µ-tdc)(H{sub 2}O)(µ-dib)]{sub n} (2), and ([Cd{sub 2}(µ{sub 3}-tdc){sub 2}(µ-dimb){sub 2}]·(H{sub 2}O)){sub n}(3). These MOFs were characterized by FT-IR spectroscopy, elemental, thermal (TG, DTA, DTG and DSC), and single-crystal X-ray diffraction analyses. Isomorphous complexes 1 and 2 reveal polycatenated 2D+2D→3D framework based on an undulated (4,4)-sql layer. Complex 3 exhibits a new 4-fold interpenetrating 3D framework with the point symbol of 6{sup 6}. Molecular simulations were used to assess the potentials of the complexes for H{sub 2} storage application. Moreover, these coordination polymers exhibit blue fluorescent emission bands in the solid state at room temperature. - Graphical abstract: In this study, hydrothermal reactions of rigid 1,4-bis(imidazol-1-yl)benzene (dib) and 1,4-bis(imidazol-1-yl)-2,5-dimethylbenzene (dimb) with deprotonated thiophene-2,5-dicarboxylic acid (H{sub 2}tdc) in the presence of Zn(II) and Cd(II) salts in H{sub 2}O produced three new metal–organic frameworks. Isomorphous complexes 1 and 2 reveal polycatenated 2D+2D→3D framework based on an undulated (4,4)-sql layer. Complex 3 exhibits a new 4-fold interpenetrating 3D framework with the point symbol of 6{sup 6}. Molecular simulations were used to assess the potentials of the complexes for H{sub 2} storage application. These coordination polymers exhibit blue fluorescent emission bands in the solid state at room temperature. Display Omitted - Highlights: • Complexes 1 and 2 display polycatenated 2D+2D→3D framework. • Complex 3 exhibits a new 4-fold interpenetrating 3D framework. • Complex 1 adsorbs the highest amount of

Diamex process: hydrolytic and radiolytic degradation of the diamide extractant DMDOHEMA

International Nuclear Information System (INIS)

Berthon, L.; Cames, B.

2000-01-01

This paper deals with the hydrolysis and radiolysis of a diamide (malonamide) which is the extractant of the DIAMEX process for the extraction of minor actinides from high level liquid radioactive waste. The semi-developed formula of the malonamides investigated is RR'NCO(CHR'')CONRR' (where R, R' and R'' are alkyl or oxy-alkyl groups). The formula of the extractant molecule has been optimized and has led to DMDOHEMA (NN'-dimethyl N,N'-di-octyl hexyl-oxy-ethyl malonamide: (C 8 H 17 (CH 3 )NCO) 2 CH(C 2 H 4 OC 6 H 13 )) which is the present reference extractant for the DIAMEX process. The aim of this study was to: -identify and quantify the main DMDOHEMA degradation products; - identify the potential degradation pathways for diamides; -correlate the concentration of the identified degradation products with the extracting properties of the spent solvents to identify the most disturbing degradation products. (authors)

Structural Characterization of the Degradation Products of a Minor Natural Sweet Diterpene Glycoside Rebaudioside M under Acidic Conditions

Directory of Open Access Journals (Sweden)

Indra Prakash

2014-01-01

Full Text Available Degradation of rebaudioside M, a minor sweet component of Stevia rebaudiana Bertoni, under conditions that simulated extreme pH and temperature conditions has been studied. Thus, rebaudioside M was treated with 0.1 M phosphoric acid solution (pH 2.0 and 80 °C temperature for 24 h. Experimental results indicated that rebaudioside M under low pH and higher temperature yielded three minor degradation compounds, whose structural characterization was performed on the basis of 1D (1H-, 13C- & 2D (COSY, HSQC, HMBC NMR, HRMS, MS/MS spectral data as well as enzymatic and acid hydrolysis studies.

Effects of permafrost degradation on alpine grassland in a semi-arid basin on the Qinghai–Tibetan Plateau

International Nuclear Information System (INIS)

Yi Shuhua; Zhou Zhaoye; Ren Shilong; Xu Ming; Qin Yu; Chen Shengyun; Ye Baisheng

2011-01-01

Permafrost on the Qinghai–Tibetan Plateau (QTP) has degraded over the last few decades. Its ecological effects have attracted great concern. Previous studies focused mostly at plot scale, and hypothesized that degradation of permafrost would cause lowering of the water table and drying of shallow soil and then degradation of alpine grassland. However, none has been done to test the hypothesis at basin scale. In this study, for the first time, we investigated the relationships between land surface temperature (LST) and fractional vegetation cover (FVC) in different types of permafrost zone to infer the limiting condition (water or energy) of grassland growth on the source region of Shule River Basin, which is located in the north-eastern edge of the QTP. LST was obtained from MODIS Aqua products at 1 km resolution, while FVC was upscaled from quadrat (50 cm) to the same resolution as LST, using 30 m resolution NDVI data of the Chinese HJ satellite. FVC at quadrat scale was estimated by analyzing pictures taken with a multi-spectral camera. Results showed that (1) retrieval of FVC at quadrat scale using a multi-spectral camera was both more accurate and more efficient than conventional methods and (2) the limiting factor of vegetation growth transitioned from energy in the extreme stable permafrost zone to water in the seasonal frost zone. Our study suggested that alpine grassland would respond differently to permafrost degradation in different types of permafrost zone. Future studies should consider overall effects of permafrost degradation, and avoid the shortcomings of existing studies, which focus too much on the adverse effects.

An Overview of Biodegradation of LNAPLs in Coastal (Semi)-arid Environment.

KAUST Repository

Yadav, Brijesh Kumar

2011-02-22

Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these organic contaminated resources is receiving increasing interests and where applicable, can serve as a cost-effective remediation alternative. The success of bioremediation greatly depends on the prevailing environmental variables, and their remediation favoring customization requires a sound understanding of their integrated behavior on fate and transport of LNAPLs under site-specific conditions. The arid and semi-arid coastal sites are characterized by specific environmental extremes; primarily, varying low and high temperatures, high salinity, water table dynamics, and fluctuating soil moisture content. An understanding of the behavior of these environmental variables on biological interactions with LNAPLs would be helpful in customizing the bioremediation for restoring problematic sites in these regions. Therefore, this paper reviews the microbial degradation of LNAPLs in soil-water, considering the influences of prevailing environmental parameters of arid and semi-arid coastal regions. First, the mechanism of biodegradation of LNAPLs is discussed briefly, followed by a summary of popular kinetic models used by researchers for describing the degradation rate of these hydrocarbons. Next, the impact of soil moisture content, water table dynamics, and soil-water temperature on the fate and transport of LNAPLs are discussed, including an overview of the studies conducted so far. Finally, based on the reviewed information, a general conclusion is presented with recommendations for future research subjects on optimizing the bioremediation technique in the field under the aforesaid environmental conditions. The present review will be useful to better understand the

Reduce land degradation, climate change and adaptation measures

International Nuclear Information System (INIS)

Sciortino, Maurizio

2015-01-01

The land degradation and desertification are a serious threat to the sustainability of production food in many areas of the Earth. the methods ecosystems and the concomitant effects management of climate change are altering the processes physical, chemical and biological processes that regulate the complex balance of terrestrial ecosystems and soil particularly in areas climatically characterized by conditions arid, semi-arid and dry sub humid areas. The RIO + 20 Conference has recognized the risk of desertification and it proposed for the post 2015 agenda the goal of a world 'Land Degradation Neutral'.The challenge of adaptation to changes climate will require a greater involvement scientific research in support of conservation and use of natural resources both in Italy and in all contexts where the challenge of sustainability of development is more urgent. [it

Cell-cycle regulation of non-enzymatic functions of the Drosophila methyltransferase PR-Set7.

Science.gov (United States)

Zouaz, Amel; Fernando, Céline; Perez, Yannick; Sardet, Claude; Julien, Eric; Grimaud, Charlotte

2018-04-06

Tight cell-cycle regulation of the histone H4-K20 methyltransferase PR-Set7 is essential for the maintenance of genome integrity. In mammals, this mainly involves the interaction of PR-Set7 with the replication factor PCNA, which triggers the degradation of the enzyme by the CRL4CDT2 E3 ubiquitin ligase. PR-Set7 is also targeted by the SCFβ-TRCP ligase, but the role of this additional regulatory pathway remains unclear. Here, we show that Drosophila PR-Set7 undergoes a cell-cycle proteolytic regulation, independently of its interaction with PCNA. Instead, Slimb, the ortholog of β-TRCP, is specifically required for the degradation of the nuclear pool of PR-Set7 prior to S phase. Consequently, inactivation of Slimb leads to nuclear accumulation of PR-Set7, which triggers aberrant chromatin compaction and G1/S arrest. Strikingly, these phenotypes result from non-enzymatic PR-Set7 functions that prevent proper histone H4 acetylation independently of H4K20 methylation. Altogether, these results identify the Slimb-mediated PR-Set7 proteolysis as a new critical regulatory mechanism required for proper interphase chromatin organization at G1/S transition.

Detection of Toluene Degradation in Bacteria Isolated from Oil Contaminated Soils

International Nuclear Information System (INIS)

Ainon Hamzah; Tavakoli, A.; Amir Rabu

2011-01-01

Toluene (C 7 H 8 ) a hydrocarbon in crude oil, is a common contaminant in soil and groundwater. In this study, the ability to degrade toluene was investigated from twelve bacteria isolates which were isolated from soil contaminated with oil. Out of 12 bacterial isolates tested, most of Pseudomonas sp. showed the capability to grow in 1 mM of toluene compared with other isolates on the third day of incubation. Based on enzyme assays towards toluene monooxygenase, Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were shown to have the highest ability to degrade toluene. The toluene monooxygenase activity was analysed by using two calorimetric methods, Horseradish peroxidase (HRP) and indole-indigo. Both of the methods measured the production of catechol by the enzymatic reaction of toluene monooxygenase. In the HRP assay, the highest enzyme activity was 0.274 U/ mL, exhibited by Pseudomonas aeruginosa UKMP-14T. However, for indole-indigo assay, Bacillus cereus UKMP-6G produced the highest enzyme activity of 0.291 U/ ml. Results from both experiments showed that Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were able to degrade toluene. (author)

Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

KAUST Repository

Croissant, Jonas G.

2017-01-13

The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

Comparative transcriptome analysis reveals different strategies for degradation of steam-exploded sugarcane bagasse by Aspergillus niger and Trichoderma reesei.

Science.gov (United States)

Borin, Gustavo Pagotto; Sanchez, Camila Cristina; de Santana, Eliane Silva; Zanini, Guilherme Keppe; Dos Santos, Renato Augusto Corrêa; de Oliveira Pontes, Angélica; de Souza, Aline Tieppo; Dal'Mas, Roberta Maria Menegaldo Tavares Soares; Riaño-Pachón, Diego Mauricio; Goldman, Gustavo Henrique; Oliveira, Juliana Velasco de Castro

2017-06-30

Second generation (2G) ethanol is produced by breaking down lignocellulosic biomass into fermentable sugars. In Brazil, sugarcane bagasse has been proposed as the lignocellulosic residue for this biofuel production. The enzymatic cocktails for the degradation of biomass-derived polysaccharides are mostly produced by fungi, such as Aspergillus niger and Trichoderma reesei. However, it is not yet fully understood how these microorganisms degrade plant biomass. In order to identify transcriptomic changes during steam-exploded bagasse (SEB) breakdown, we conducted a RNA-seq comparative transcriptome profiling of both fungi growing on SEB as carbon source. Particular attention was focused on CAZymes, sugar transporters, transcription factors (TFs) and other proteins related to lignocellulose degradation. Although genes coding for the main enzymes involved in biomass deconstruction were expressed by both fungal strains since the beginning of the growth in SEB, significant differences were found in their expression profiles. The expression of these enzymes is mainly regulated at the transcription level, and A. niger and T. reesei also showed differences in TFs content and in their expression. Several sugar transporters that were induced in both fungal strains could be new players on biomass degradation besides their role in sugar uptake. Interestingly, our findings revealed that in both strains several genes that code for proteins of unknown function and pro-oxidant, antioxidant, and detoxification enzymes were induced during growth in SEB as carbon source, but their specific roles on lignocellulose degradation remain to be elucidated. This is the first report of a time-course experiment monitoring the degradation of pretreated bagasse by two important fungi using the RNA-seq technology. It was possible to identify a set of genes that might be applied in several biotechnology fields. The data suggest that these two microorganisms employ different strategies for biomass

Kinetics of enzymatic hydrolysis of methyl ricinoleate

OpenAIRE

Neeharika, T. S.V.R.; Lokesh, P.; Prasanna Rani, K. N.; Prathap Kumar, T.; Prasad, R. B.N.

2015-01-01

Ricinoleic acid is an unsaturated hydroxy fatty acid that naturally occurs in castor oil in proportions of up to 85–90%. Ricinoleic acid is a potential raw material and finds several applications in coatings, lubricant formulations and pharmaceutical areas. Enzymatic hydrolysis of castor oil is preferred over conventional hydrolysis for the preparation of ricinoleic acid to avoid estolide formation. A kinetics analysis of the enzymatic hydrolysis of Methyl Ricinoleate in the presence of Candi...

Single-tube library preparation for degraded DNA

DEFF Research Database (Denmark)

Carøe, Christian; Gopalakrishnan, Shyam; Vinner, Lasse

2018-01-01

these obstacles and enable higher throughput are therefore of interest to researchers working with degraded DNA. 2.In this study, we compare four Illumina library preparation protocols, including two “single-tube” methods developed for this study with the explicit aim of improving data quality and reducing...... of chemically damaged and highly fragmented DNA molecules. In particular, the enzymatic reactions and DNA purification steps during library preparation can result in DNA template loss and sequencing biases, affecting downstream analyses. The development of library preparation methods that circumvent...... preparation time and expenses. The methods are tested on grey wolf (Canis lupus) museum specimens. 3.We found single-tube protocols increase library complexity, yield more reads that map uniquely to the reference genome, reduce processing time, and may decrease laboratory costs by 90%. 4.Given the advantages...

Thermo-Mechanical Properties of Semi-Degradable Poly(β-amino ester)-co-Methyl Methacrylate Networks under Simulated Physiological Conditions

Science.gov (United States)

Safranski, David L.; Crabtree, Jacob C.; Huq, Yameen R.; Gall, Ken

2011-01-01

Poly(β-amino ester) networks are being explored for biomedical applications, but they may lack the mechanical properties necessary for long term implantation. The objective of this study is to evaluate the effect of adding methyl methacrylate on networks' mechanical properties under simulated physiological conditions. The networks were synthesized in two parts: (1) a biodegradable crosslinker was formed from a diacrylate and amine, (2) and then varying concentrations of methyl methacrylate were added prior to photopolymerizing the network. Degradation rate, mechanical properties, and glass transition temperature were studied as a function of methyl methacrylate composition. The crosslinking density played a limited role on mechanical properties for these networks, but increasing methyl methacrylate concentration improved the toughness by several orders of magnitude. Under simulated physiological conditions, networks showed increasing toughness or sustained toughness as degradation occurred. This work establishes a method of creating degradable networks with tailorable toughness while undergoing partial degradation. PMID:21966028

Purification and Characterization of a Novel β-Cypermethrin-Degrading Aminopeptidase from Pseudomonas aeruginosa GF31.

Science.gov (United States)

Tang, Ai-Xing; Liu, Hu; Liu, You-Yan; Li, Qing-Yun; Qing, Yi-Ming

2017-11-01

In this study, a novel β-cypermethrin-degrading enzyme was isolated and purified by 32.8 fold from the extracellular cell-free filtrate of Pseudomonas aeruginosa GF31with the protein recovery of 26.6%. The molecular mass of the enzyme was determined to be 53 kDa. The optimum temperature for the activity was surprisingly 60 °C, and moreover, the purified enzyme showed a good pH stability, maintaining over 85% of its initial activity in the pH 5.0-9.0 range. Most of the common metal ions exhibited little influence on the activity except for Hg 2+ , Ag + , and Cu 2+ . After the complete gene sequence of the degrading enzyme was obtained by subcloning, sequence analyses as well as enzymatic properties demonstrated that the islolated enzyme should be an aminopeptidase. This is the first reported aminopeptidase for pyrethroid hydrolase, providing new potential enzyme resources for the degradation of this type of pesticide.

Chondroitinase C Selectively Degrades Chondroitin Sulfate Glycosaminoglycans that Inhibit Axonal Growth within the Endoneurium of Peripheral Nerve.

Science.gov (United States)

Graham, James B; Muir, David

2016-01-01

The success of peripheral nerve regeneration is highly dependent on the regrowth of axons within the endoneurial basal lamina tubes that promote target-oriented pathfinding and appropriate reinnervation. Restoration of nerve continuity at this structural level after nerve transection injury by direct repair and nerve grafting remains a major surgical challenge. Recently, biological approaches that alter the balance of growth inhibitors and promoters in nerve have shown promise to improve appropriate axonal regeneration and recovery of peripheral nerve function. Chondroitin sulfate proteoglycans (CSPGs) are known inhibitors of axonal growth. This growth inhibition is mainly associated with a CSPG's glycosaminoglycan chains. Enzymatic degradation of these chains with chondroitinase eliminates this inhibitory activity and, when applied in vivo, can improve the outcome of nerve repair. To date, these encouraging findings were obtained with chondroitinase ABC (a pan-specific chondroitinase). The aim of this study was to examine the distribution of CSPG subtypes in rodent, rabbit, and human peripheral nerve and to test more selective biological enzymatic approaches to improve appropriate axonal growth within the endoneurium and minimize aberrant growth. Here we provide evidence that the endoneurium, but not the surrounding epineurium, is rich in CSPGs that have glycosaminoglycan chains readily degraded by chondroitinase C. Biochemical studies indicate that chondroitinase C has degradation specificity for 6-sulfated glycosaminoglycans found in peripheral nerve. We found that chondroitinase C degrades and inactivates inhibitory CSPGs within the endoneurium but not so much in the surrounding nerve compartments. Cryoculture bioassays (neurons grown on tissue sections) show that chondroitinase C selectively and significantly enhanced neuritic growth associated with the endoneurial basal laminae without changing growth-inhibiting properties of the surrounding epineurium

Enzymatic synthesis of vanillin

NARCIS (Netherlands)

van den Heuvel, RHH; Fraaije, MW; Laane, C; van Berkel, WJH; Heuvel, Robert H.H. van den; Berkel, Willem J.H. van

Due to increasing interest in natural vanillin, two enzymatic routes for the synthesis of vanillin were developed. The flavoprotein vanillyl alcohol oxidase (VAO) acts on a wide range of phenolic compounds and converts both creosol and vanillylamine to vanillin with high yield. The VAO-mediated

Enzymatic synthesis of vanillin

NARCIS (Netherlands)

Heuvel, van den R.H.H.; Fraaije, M.W.; Laane, C.; Berkel, van W.J.H.

2001-01-01

Due to increasing interest in natural vanillin, two enzymatic routes for the synthesis of vanillin were developed. The flavoprotein vanillyl alcohol oxidase (VAO) acts on a wide range of phenolic compounds and converts both creosol and vanillylamine to vanillin with high yield. The VAO-mediated

Enzymatic network for production of ether amines from alcohols

NARCIS (Netherlands)

Palacio, Cyntia M.; Crismaru, Gica Ciprian; Bartsch, Sebastian; Navickas, Vaidotas; Ditrich, Klaus; Breuer, Michael; Abu, Rohana; Woodley, John; Baldenius, Kai-Uwe; Wu, Bian; Janssen, Dick

We constructed an enzymatic network composed of three different enzymes for the synthesis of valuable ether amines. The enzymatic reactions are interconnected to catalyze the oxidation and subsequent transamination of the substrate and to provide cofactor recycling. This allows production of the

Recent insights in enzymatic synthesis of fructooligosaccharides from inulin.

Science.gov (United States)

Singh, Ram Sarup; Singh, Rupinder Pal; Kennedy, John F

2016-04-01

In the past few years, people are paying more attention to their dietary habits, and functional foods are playing a key role in maintaining the health of man. Prebiotics are considered as a main component of the functional foods which are usually composed of short chains of carbohydrates. Fructooligosaccharides (FOSs) are considered as one of the main group of prebiotics which have recognisable bifidogenic properties. FOSs are obtained either by extraction from various plant materials or by enzymatic synthesis from different substrates. Enzymatically, these can be obtained either from sucrose using fructosyltransferase or from inulin by endoinulinase. Inulin is a potent substrate for the enzymatic production of FOSs. This review article will provide an overview on the inulin as potent substrate, microbial sources of endoinulinases, enzymatic synthesis of FOSs from inulin, commercial status of FOSs, and their future perspectives. Copyright © 2016 Elsevier B.V. All rights reserved.

Climate change mitigation by carbon stock - the case of semi-arid West Africa

Science.gov (United States)

Lykke, A. M.; Barfod, A. S.; Tinggaard Svendsen, G.; Greve, M.; Svenning, J.-C.

2009-11-01

Semi-arid West Africa has not been integrated into the afforestation/reforestation (AR) carbon market. Most projects implemented under the Clean Development Mechanism (CDM) have focused on carbon emission reductions from industry and energy consumption, whereas only few (only one in West Africa) have been certified for AR carbon sequestration. A proposed mechanism, Reducing Emissions from Deforestation and Degradation (REDD) to be discussed under COP15 aims to reduce emissions by conserving already existing forests. REDD has high potential for carbon stocking at low costs, but focuses primarily on rain forest countries and excludes semi-arid West Africa from the preliminary setup. African savannas have potential to store carbon in the present situation with degrading ecosystems and relatively low revenues from crops and cattle, especially if it is possible to combine carbon stocking with promotion of secondary crops such as food resources and traditional medicines harvested on a sustainable basis. Methods for modelling and mapping of potential carbon biomass are being developed, but are still in a preliminary state. Although economic benefits from the sale of carbon credits are likely to be limited, carbon stocking is an interesting option if additional benefits are considered such as improved food security and protection of biodiversity.

Climate change mitigation by carbon stock - the case of semi-arid West Africa

International Nuclear Information System (INIS)

Lykke, A M; Barfod, A S; Greve, M; Svenning, J-C; Svendsen, G Tinggaard

2009-01-01

Semi-arid West Africa has not been integrated into the afforestation/reforestation (AR) carbon market. Most projects implemented under the Clean Development Mechanism (CDM) have focused on carbon emission reductions from industry and energy consumption, whereas only few (only one in West Africa) have been certified for AR carbon sequestration. A proposed mechanism, Reducing Emissions from Deforestation and Degradation (REDD) to be discussed under COP15 aims to reduce emissions by conserving already existing forests. REDD has high potential for carbon stocking at low costs, but focuses primarily on rain forest countries and excludes semi-arid West Africa from the preliminary setup. African savannas have potential to store carbon in the present situation with degrading ecosystems and relatively low revenues from crops and cattle, especially if it is possible to combine carbon stocking with promotion of secondary crops such as food resources and traditional medicines harvested on a sustainable basis. Methods for modelling and mapping of potential carbon biomass are being developed, but are still in a preliminary state. Although economic benefits from the sale of carbon credits are likely to be limited, carbon stocking is an interesting option if additional benefits are considered such as improved food security and protection of biodiversity.

Wind Erosion Induced Soil Degradation in Northern China: Status, Measures and Perspective

Directory of Open Access Journals (Sweden)

Zhongling Guo

2014-12-01

Full Text Available Soil degradation is one of the most serious ecological problems in the world. In arid and semi-arid northern China, soil degradation predominantly arises from wind erosion. Trends in soil degradation caused by wind erosion in northern China frequently change with human activities and climatic change. To decrease soil loss by wind erosion and enhance local ecosystems, the Chinese government has been encouraging residents to reduce wind-induced soil degradation through a series of national policies and several ecological projects, such as the Natural Forest Protection Program, the National Action Program to Combat Desertification, the “Three Norths” Shelter Forest System, the Beijing-Tianjin Sand Source Control Engineering Project, and the Grain for Green Project. All these were implemented a number of decades ago, and have thus created many land management practices and control techniques across different landscapes. These measures include conservation tillage, windbreak networks, checkerboard barriers, the Non-Watering and Tube-Protecting Planting Technique, afforestation, grassland enclosures, etc. As a result, the aeolian degradation of land has been controlled in many regions of arid and semiarid northern China. However, the challenge of mitigating and further reversing soil degradation caused by wind erosion still remains.

Simulation on the Performance of a Driven Fan Made by Polyester/Epoxy interpenetrate polymer network (IPN)

Science.gov (United States)

Fahrul Hassan, Mohd; Jamri, Azmil; Nawawi, Azli; Zaini Yunos, Muhamad; Fauzi Ahmad, Md; Adzila, Sharifah; Nasrull Abdol Rahman, Mohd

2017-08-01

The main purpose of this study is to investigate the performance of a driven fan design made by Polyester/Epoxy interpenetrate polymer network (IPN) material that specifically used for turbocharger compressor. Polyester/Epoxy IPN is polymer plastics that was used as replacements for traditional polymers and has been widely used in a variety of applications because of their limitless conformations. Simulation based on several parameters which are air pressure, air velocity and air temperature have been carried out for a driven fan design performance of two different materials, aluminum alloy (existing driven fan design) and Polyester/Epoxy IPN using SolidWorks Flow Simulation software. Results from both simulations were analyzed and compared where both materials show similar performance in terms of air pressure and air velocity due to similar geometric and dimension, but Polyester/Epoxy IPN produces lower air temperature than aluminum alloy. This study shows a preliminary result of the potential Polyester/Epoxy IPN to be used as a driven fan design material. In the future, further studies will be conducted on detail simulation and experimental analysis.

Segmental dynamics in poly(methyl acrylate)-poly(methyl methacrylate) sequential interpenetrating polymer networks: structural relaxation experiments

International Nuclear Information System (INIS)

Ribelles, J L Gomez; Duenas, J M Meseguer; Cabanilles, C Torregrosa; Pradas, M Monleon

2003-01-01

The miscibility of poly(methyl acrylate)-poly(methyl methacrylate) sequential interpenetrating polymer networks (IPNs) has been studied by probing the conformational mobility of the component polymer chains. These IPNs exhibit the phenomenon of forced compatibilization. In a conventional heating differential scanning calorimetry (DSC) thermogram, the highly cross-linked IPN shows a single glass transition which covers a temperature interval of around 100 d eg C; in contrast, loosely cross-linked IPNs show two glass transitions. The conformational mobility in these IPNs is studied by subjecting them to isothermal annealings at temperatures in the region of the glass transition and below it. The DSC scans measured after these treatments allow one to determine the temperature interval in which the sample is out of thermodynamic equilibrium but keeps enough conformational mobility to relax during the isothermal annealing in such a way that the enthalpy loss is measurable with the sensitivity of a conventional DSC. The results allow one to reach some conclusions about the compositional distribution of the IPN on the nanometre scale

Alginate-polyvinyl alcohol based interpenetrating polymer network for prolonged drug therapy, Optimization and in-vitro characterization.

Science.gov (United States)

Anwar, Hina; Ahmad, Mahmood; Minhas, Muhammad Usman; Rehmani, Sahrish

2017-06-15

A new natural and synthetic polymeric blend to form interpenetrating polymer network (IPN) hydrogels was synthesized utilizing sodium alginate and PVA as polymers by free radical polymerization employing 2-Acylamido-2-methylpropane-sulfonic acid as monomer (AMPS) and tramadol HCl as model drug through 3 2 level full factorial design to evaluate the impact of selected independent factors i.e. polymer (sodium alginate) and monomer (AMPS) contents on swelling index at 18th hour, percent drug release at 18th hour, time required for 80% drug release and drug entrapment efficiency as dependent variables. FTIR, SEM, sol-gel analysis, equilibrium swelling studies and in-vitro release kinetics were performedfor in-vitro characterization of formulated IPN hydrogels. In-vitro studies carried out at pH 1.2 and pH 7.4 revealed pH independent swelling and drug release from polymeric IPN, providing controlled drug release for an extended period of time with improved entrapment efficiency, thereby concluding that this polymeric blend may be a promising system for the prolonged drug delivery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Printing continuously graded interpenetrating polymer networks of acrylate/epoxy by manipulating cationic network formation during stereolithography

Directory of Open Access Journals (Sweden)

W. Li

2016-12-01

Full Text Available Ultra-violet (UV laser assisted stereolithography is used to print graded interpenetrating polymer networks (IPNs by controlling network formation. Unlike the traditional process where structural change in IPNs is achieved by varying the feeding ratio of monomers or polymer precursors, in this demonstration property is changed by controlled termination of network formation. A photo-initiated process is used to construct IPNs by a combination of radical and cationic network formation in an acrylate/epoxy system. The extent of the cationic network formation is used to control the final properties of the system. Rapid-Scan Fourier Transformation Infrared Spectroscopy (RS-FTIR is used to track the curing kinetics of the two networks and identify key parameters to control the final properties. Atomic force microscopy (AFM and differential scanning calorimetry (DSC confirm the formation of homogenous IPNs, whereas nano-indentation indicates that properties vary with the extent of cationic network formation. The curing characteristics are used to design and demonstrate printing of graded IPNs that show two orders of magnitude variation in mechanical properties in the millimeter scale.

Interpenetrated polymer networks based on commercial silicone elastomers and ionic networks with high dielectric permittivity and self-healing properties

DEFF Research Database (Denmark)

Ogliani, Elisa; Yu, Liyun; Skov, Anne Ladegaard

the applicability. One method used to avoid this limitation is to increase the dielectric permittivity of the material in order to improve the actuation response at a given field. Recently, interpenetrating polymer networks (IPNs) based on covalently cross-linked commercial silicone elastomers and ionic networks...... from amino- and carboxylic acid- functional silicones have been designed[2] (Figure 1). This novel system provides both the mechanical stability and the high breakdown strength given by the silicone part of the IPNs and the high permittivity and the softening effect of the ionic network. Thus......,1 Hz), and the commercial elastomers RT625 and LR3043/30 provide thebest viscoelastic properties to the systems, since they maintain low viscous losses upon addition of ionic network. The values ofthe breakdown strength in all cases remain higher than that of the reference pure PDMS network (ranging...

Comparison of sodium carbonate-oxygen and sodium hydroxide-oxygen pretreatments on the chemical composition and enzymatic saccharification of wheat straw.

Science.gov (United States)

Geng, Wenhui; Huang, Ting; Jin, Yongcan; Song, Junlong; Chang, Hou-Min; Jameel, Hasan

2014-06-01

Pretreatment of wheat straw with a combination of sodium carbonate (Na2CO3) or sodium hydroxide (NaOH) with oxygen (O2) 0.5MPa was evaluated for its delignification ability at relatively low temperature 110°C and for its effect on enzymatic hydrolysis efficiency. In the pretreatment, the increase of alkali charge (as Na2O) up to 12% for Na2CO3 and 6% for NaOH, respectively, resulted in enhancement of lignin removal, but did not significantly degrade cellulose and hemicellulose. When the pretreated solid was hydrolyzed with a mixture of cellulases and hemicellulases, the sugar yield increased rapidly with the lignin removal during the pretreatment. A total sugar yield based on dry matter of raw material, 63.8% for Na2CO3-O2 and 71.9% for NaOH-O2 was achieved under a cellulase loading of 20FPU/g-cellulose. The delignification efficiency and total sugar yield from enzymatic hydrolysis were comparable to the previously reported results at much higher temperature without oxygen. Copyright © 2014 Elsevier Ltd. All rights reserved.

Metabolism Dealing with Thermal Degradation of NAD+ in the Hyperthermophilic Archaeon Thermococcus kodakarensis.

Science.gov (United States)

Hachisuka, Shin-Ichi; Sato, Takaaki; Atomi, Haruyuki

2017-10-01

NAD + is an important cofactor for enzymatic oxidation reactions in all living organisms, including (hyper)thermophiles. However, NAD + is susceptible to thermal degradation at high temperatures. It can thus be expected that (hyper)thermophiles harbor mechanisms that maintain in vivo NAD + concentrations and possibly remove and/or reuse undesirable degradation products of NAD + Here we confirmed that at 85°C, thermal degradation of NAD + results mostly in the generation of nicotinamide and ADP-ribose, the latter known to display toxicity by spontaneously linking to proteins. The hyperthermophilic archaeon Thermococcus kodakarensis possesses a putative ADP-ribose pyrophosphatase (ADPR-PPase) encoded by the TK2284 gene. ADPR-PPase hydrolyzes ADP-ribose to ribose 5-phosphate (R5P) and AMP. The purified recombinant TK2284 protein exhibited activity toward ADP-ribose as well as ADP-glucose. Kinetic analyses revealed a much higher catalytic efficiency toward ADP-ribose, suggesting that ADP-ribose was the physiological substrate. To gain insight into the physiological function of TK2284, a TK2284 gene disruption strain was constructed and examined. Incubation of NAD + in the cell extract of the mutant strain at 85°C resulted in higher ADP-ribose accumulation and lower AMP production compared with those in experiments with the host strain cell extract. The mutant strain also exhibited lower cell yield and specific growth rates in a synthetic amino acid medium compared with those of the host strain. The results obtained here suggest that the ADPR-PPase in T. kodakarensis is responsible for the cleavage of ADP-ribose to R5P and AMP, providing a means to utilize the otherwise dead-end product of NAD + breakdown. IMPORTANCE Hyperthermophilic microorganisms living under high temperature conditions should have mechanisms that deal with the degradation of thermolabile molecules. NAD + is an important cofactor for enzymatic oxidation reactions and is susceptible to thermal

Exploring 3D non-interpenetrated metal-organic framework with malonate-bridged Co(II) coordination polymer: structural elucidation and theoretical study

Science.gov (United States)

Hossain, Anowar; Mandal, Tripti; Mitra, Monojit; Manna, Prankrishna; Bauzá, Antonio; Frontera, Antonio; Seth, Saikat Kumar; Mukhopadhyay, Subrata

2017-12-01

A Co(II)-based coordination polymer with tetranuclear cobalt(II)-malonate cluster has been easily generated by aqueous medium self-assembly from Cobalt(II) chloride hexahydrate and malonic acid. The structure exhibits a non-interpenetrating, highly undulating two-dimensional (2D) bi-layer network with (4,4) topology. The crystal structure is composed of infinite interdigitated 2D metal-organic bi-layers which extended to an intricate 3D framework through the interbilayer hydrogen bonds. We have studied energetically by means of Density Functional Theory (DFT) calculations the H-bonding interactions that connect the 2D metal-organic bi-layers. The finite theoretical models have been used to compute conventional O‒H•••O and unconventional C‒H•••O interactions which plays a key role to build 3D architecture.

Formation of semi-IPN membrane composed of crosslinked SPS-[PVdF-co-HFP/Nafion] for application in DMFC: A fine tuning between crosslinker and initiator

Energy Technology Data Exchange (ETDEWEB)

Kumar, Piyush; Kundu, Patit Paban, E-mail: ppk923@yahoo.com

2015-08-15

The semi-interpenetrating (semi-IPN) membrane composed of crosslinked sulfonated polystyrene (SPS) within the host blend of PVdF-co-HFP (Polyvinylidenefluoride-co-hexafluoropropylene) and Nafion has already been tested as a promising polymer electrolyte membrane (PEM) in terms of improved water uptake, proton conductivity and electrical efficiency for application in the direct methanol fuel cell (DMFC). These desired results have generated further curiosity about a fine tuning between the contents of divinyl benzene (DVB) as a crosslinker and azobisisobutyronitrile (AIBN) as an initiator for the optimization of PEM characteristics. It has been observed that an increase in AIBN content leads to an acceptable degree of water uptake, swelling ratio and proton conductivity in PEM, while higher DVB content causes declined methanol crossover, leading to higher membrane selectivity. These two opposing effects are optimized in terms of proton conductivity, tensile strength and membrane selectivity for the membrane consisting of 0.4 wt% of AIBN and 1.2 wt% of DVB. Moreover, the maximum power density obtained for the membrane having optimum selectivity is 56 mW cm{sup −2}, when analyzed at 90 °C. These results indicate that one can achieve a high power density in comparison to Nafion by fine tuning the contents of initiator and cross-linker during the synthesis of the semi-IPN membrane. - Graphical abstract: Display Omitted - Highlights: • PEM composed of 0.4/1.2 wt% of AIBN/DVB produced best result. • Lower methanol crossover (1.02 × 10{sup −6} cm{sup 2} s{sup −1}) compare to Nafion-117. • Higher membrane selectivity i.e 3.05 × 10{sup 4} Ss cm{sup −3} was obtained. • A maximum power density of 56 mW cm{sup −2} was obtained at 90 °C.

Formation of semi-IPN membrane composed of crosslinked SPS-[PVdF-co-HFP/Nafion] for application in DMFC: A fine tuning between crosslinker and initiator

International Nuclear Information System (INIS)

Kumar, Piyush; Kundu, Patit Paban

2015-01-01

The semi-interpenetrating (semi-IPN) membrane composed of crosslinked sulfonated polystyrene (SPS) within the host blend of PVdF-co-HFP (Polyvinylidenefluoride-co-hexafluoropropylene) and Nafion has already been tested as a promising polymer electrolyte membrane (PEM) in terms of improved water uptake, proton conductivity and electrical efficiency for application in the direct methanol fuel cell (DMFC). These desired results have generated further curiosity about a fine tuning between the contents of divinyl benzene (DVB) as a crosslinker and azobisisobutyronitrile (AIBN) as an initiator for the optimization of PEM characteristics. It has been observed that an increase in AIBN content leads to an acceptable degree of water uptake, swelling ratio and proton conductivity in PEM, while higher DVB content causes declined methanol crossover, leading to higher membrane selectivity. These two opposing effects are optimized in terms of proton conductivity, tensile strength and membrane selectivity for the membrane consisting of 0.4 wt% of AIBN and 1.2 wt% of DVB. Moreover, the maximum power density obtained for the membrane having optimum selectivity is 56 mW cm −2 , when analyzed at 90 °C. These results indicate that one can achieve a high power density in comparison to Nafion by fine tuning the contents of initiator and cross-linker during the synthesis of the semi-IPN membrane. - Graphical abstract: Display Omitted - Highlights: • PEM composed of 0.4/1.2 wt% of AIBN/DVB produced best result. • Lower methanol crossover (1.02 × 10 −6 cm 2 s −1 ) compare to Nafion-117. • Higher membrane selectivity i.e 3.05 × 10 4 Ss cm −3 was obtained. • A maximum power density of 56 mW cm −2 was obtained at 90 °C

Soil bacterial diversity in degraded and restored lands of Northeast Brazil.

Science.gov (United States)

Araújo, Ademir Sérgio Ferreira; Borges, Clovis Daniel; Tsai, Siu Mui; Cesarz, Simone; Eisenhauer, Nico

2014-11-01

Land degradation deteriorates biological productivity and affects environmental, social, and economic sustainability, particularly so in the semi-arid region of Northeast Brazil. Although some studies exist reporting gross measures of soil microbial parameters and processes, limited information is available on how land degradation and restoration strategies influence the diversity and composition of soil microbial communities. In this study we compare the structure and diversity of bacterial communities in degraded and restored lands in Northeast Brazil and determine the soil biological and chemical properties influencing bacterial communities. We found that land degradation decreased the diversity of soil bacteria as indicated by both reduced operational taxonomic unit (OTU) richness and Shannon index. Soils under native vegetation and restoration had significantly higher bacterial richness and diversity than degraded soils. Redundancy analysis revealed that low soil bacterial diversity correlated with a high respiratory quotient, indicating stressed microbial communities. By contrast, soil bacterial communities in restored land positively correlated with high soil P levels. Importantly, however, we found significant differences in the soil bacterial community composition under native vegetation and in restored land, which may indicate differences in their functioning despite equal levels of bacterial diversity.

Kinetic studies of uranyl ion adsorption on acrylonitrile (AN) / polyethylene glycol (PEG) interpenetrating networks (IPN)

International Nuclear Information System (INIS)

Aycik, G.A.; Gurellier, R.

2004-01-01

The kinetics of the adsorption of uranyl ions on amidoximated acrylonitrile (AN)/ polyethylene glycol (PEG) interpenetrating network (IPNs) from aqueous solutions was studied as a function of time and temperature. Adsorption analyses were performed for definite uranyl ion concentrations of 1x10 -2 M and at four different temperatures as 290K, 298K, 308K and 318K. Adsorption time was increased from zero to 48 hours. Adsorption capacities of uranyl ions by PEG/AN IPNS were determined by gamma spectrometer. The results indicate that adsorption capacity increases linearly with increasing temperature. The max adsorption capacity was found as 602 mgu/g IPN at 308K. Adsorption rate was evaluated from the curve plotted of adsorption capacity versus time, for each temperature. Rate constants for uranyl ions adsorption on amidoximated ipns were calculated for 290K, 298K, 308K and 318K at the solution concentration of 1x10 -2 M . The results showed that as the temperature increases the rate constant increases exponentially too. The mean activation energy of uranyl ions adsorption was found as 34.6 kJ/mole by using arrhenius equation. (author)

Enzymatic tailoring of oleuropein from Olea europaea leaves and product identification by HRMS/MS spectrometry.

Science.gov (United States)

Nikolaivits, Efstratios; Termentzi, Aikaterini; Skaltsounis, Alexios-Leandros; Fokialakis, Nikolas; Topakas, Evangelos

2017-07-10

Oleuropein, a bioactive compound found in all parts of olive tree, especially in leaves and branches, presents numerous health promoting properties that increase research and market interest the last few years. In addition, oleuropein degradation products, such as hydroxytyrosol, elenolic acid, and the aglycones also exhibit biological activities with different properties compared to the starting compound. Under this view, a commercial lipase preparation Lipolase 100L and a thermophilic β-glucosidase from Myceliophthora thermophila were used for the regioselective hydrolysis of oleuropein towards the production of the corresponding biologically active compounds. The enzymatic degradation products of oleuropein, such as hydroxytyrosol, elenolic acid and its glucoside, and oleuropein aglycones were identified by LC-HRMS/MS and NMR spectroscopy. The latter, was found as a mix of diastereomers of the monoaldehydic form of oleuropein aglycone, identified as (5S, 8R, 9S)-, (5S, 8S, 9S)- and (5S, 8R, 9R). The high substrate specificity exhibited by both lipase and β-glucosidase allows the successful tailoring of oleuropein towards the production of different biologically active compounds with significant potential in the cosmeceutical and food industry. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental studies of collisional plasma shocks and plasma interpenetration via merging supersonic plasma jets

Science.gov (United States)

Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.

2015-11-01

Over the past 4 years on the Plasma Liner Experiment (PLX) at LANL, we have studied obliquely and head-on-merging supersonic plasma jets of an argon/impurity or hydrogen/impurity mixture. The jets are formed/launched by pulsed-power-driven railguns. In successive experimental campaigns, we characterized the (a) evolution of plasma parameters of a single plasma jet as it propagated up to ~ 1 m away from the railgun nozzle, (b) density profiles and 2D morphology of the stagnation layer and oblique shocks that formed between obliquely merging jets, and (c) collisionless interpenetration transitioning to collisional stagnation between head-on-merging jets. Key plasma diagnostics included a fast-framing CCD camera, an 8-chord visible interferometer, a survey spectrometer, and a photodiode array. This talk summarizes the primary results mentioned above, and highlights analyses of inferred post-shock temperatures based on observations of density gradients that we attribute to shock-layer thickness. We also briefly describe more recent PLX experiments on Rayleigh-Taylor-instability evolution with magnetic and viscous effects, and potential future collisionless shock experiments enabled by low-impurity, higher-velocity plasma jets formed by contoured-gap coaxial guns. Supported by DOE Fusion Energy Sciences and LANL LDRD.

Preparation of supramolecular hydrogel-enzyme hybrids exhibiting biomolecule-responsive gel degradation.

Science.gov (United States)

Shigemitsu, Hajime; Fujisaku, Takahiro; Onogi, Shoji; Yoshii, Tatsuyuki; Ikeda, Masato; Hamachi, Itaru

2016-09-01

Hydrogelators are small, self-assembling molecules that form supramolecular nanofiber networks that exhibit unique dynamic properties. Development of supramolecular hydrogels that degrade in response to various biomolecules could potentially be used for applications in areas such as drug delivery and diagnostics. Here we provide a synthetic procedure for preparing redox-responsive supramolecular hydrogelators that are used to create hydrogels that degrade in response to oxidizing or reducing conditions. The synthesis takes ∼2-4 d, and it can potentially be carried out in parallel to prepare multiple hydrogelator candidates. This described solid-phase peptide synthesis protocol can be used to produce previously described hydrogelators or to construct a focused molecular library to efficiently discover and optimize new hydrogelators. In addition, we describe the preparation of redox-responsive supramolecular hydrogel-enzyme hybrids that are created by mixing aqueous solutions of hydrogelators and enzymes, which requires 2 h for completion. The resultant supramolecular hydrogel-enzyme hybrids exhibit gel degradation in response to various biomolecules, and can be rationally designed by connecting the chemical reactions of the hydrogelators with enzymatic reactions. Gel degradation in response to biomolecules as triggers occurs within a few hours. We also describe the preparation of hydrogel-enzyme hybrids arrayed on flat glass slides, enabling high-throughput analysis of biomolecules such as glucose, uric acid, lactate and so on by gel degradation, which is detectable by the naked eye. The protocol requires ∼6 h to prepare the hydrogel-enzyme hybrid array and to complete the biomolecule assay.

Fourier transform infrared spectroscopy to quantify collagen and elastin in an in vitro model of extracellular matrix degradation in aorta.

Science.gov (United States)

Cheheltani, Rabee; McGoverin, Cushla M; Rao, Jayashree; Vorp, David A; Kiani, Mohammad F; Pleshko, Nancy

2014-06-21

Extracellular matrix (ECM) is a key component and regulator of many biological tissues including aorta. Several aortic pathologies are associated with significant changes in the composition of the matrix, especially in the content, quality and type of aortic structural proteins, collagen and elastin. The purpose of this study was to develop an infrared spectroscopic methodology that is comparable to biochemical assays to quantify collagen and elastin in aorta. Enzymatically degraded porcine aorta samples were used as a model of ECM degradation in abdominal aortic aneurysm (AAA). After enzymatic treatment, Fourier transform infrared (FTIR) spectra of the aortic tissue were acquired by an infrared fiber optic probe (IFOP) and FTIR imaging spectroscopy (FT-IRIS). Collagen and elastin content were quantified biochemically and partial least squares (PLS) models were developed to predict collagen and elastin content in aorta based on FTIR spectra. PLS models developed from FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (RMSE of validation = 8.4% and 11.1% of the range respectively), and IFOP spectra were successfully used to predict elastin content (RMSE = 11.3% of the range). The PLS regression coefficients from the FT-IRIS models were used to map collagen and elastin in tissue sections of degraded porcine aortic tissue as well as a human AAA biopsy tissue, creating a similar map of each component compared to histology. These results support further application of FTIR spectroscopic techniques for evaluation of AAA tissues.

Fourier Transform Infrared Spectroscopy to Quantify Collagen and Elastin in an In Vitro Model of Extracellular Matrix Degradation in Aorta

Science.gov (United States)

Cheheltani, Rabee; McGoverin, Cushla M.; Rao, Jayashree; Vorp, David A.; Kiani, Mohammad F.; Pleshko, N.

2014-01-01

Extracellular matrix (ECM) is a key component and regulator of many biological tissues including aorta. Several aortic pathologies are associated with significant changes in the composition of the matrix, especially in the content, quality and type of aortic structural proteins, collagen and elastin. The purpose of this study was to develop an infrared spectroscopic methodology that is comparable to biochemical assays to quantify collagen and elastin in aorta. Enzymatically degraded porcine aorta samples were used as a model of ECM degradation in abdominal aortic aneurysm (AAA). After enzymatic treatment, Fourier transform infrared (FTIR) spectra of the aortic tissue were acquired by an infrared fiber optic probe (IFOP) and FTIR imaging spectroscopy (FT-IRIS). Collagen and elastin content were quantified biochemically and partial least squares (PLS) models were developed to predict collagen and elastin content in aorta based on FTIR spectra. PLS models developed from FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (RMSE of validation = 8.4% and 11.1% of the range respectively), and IFOP spectra were successfully used to predict elastin content (RMSE = 11.3% of the range). The PLS regression coefficients from the FT-IRIS models were used to map collagen and elastin in tissue sections of degraded porcine aortic tissue as well as a human AAA biopsy tissue, creating a similar map of each component compared to histology. These results support further application of FTIR spectroscopic techniques for evaluation of AAA tissues. PMID:24761431

Enzymatic synthesis of 13N-β-nicotinamide adenine dinucleotide

International Nuclear Information System (INIS)

Lambrecht, R.H.D.; Slegers, G.; Claeys, A.; Vandecasteele, C.

1985-01-01

Nitrogen-13-labelled β-nicotinamide adenine dinucleotide ( 13 N-NAD) is an interesting new compound for positron emission tomography. A semi-automatic production method is developed that yields a solution of 13 N-NAD of radiopharmaceutical quality, suitable for human intravenous administration. The 13 N-NAD is prepared enzymatically in one step from cyclotron-produced 13 NH 3 and nicotinic acid adenine dinucleotide (deamido-NAD). The enzyme NAD synthetase (E.C. 6.3.1.5), catalysing this reaction, is extracted and purified from Escherichia coli. The purified enzyme is immobilized by glutaraldehyde coupling to γ-aminopropylsilane-coated porous glass beads. The enzyme-loaded glass beads are packed in a column. The kinetic properties of the column are optimized. For synthetizing 13 N-NAD, the mixture of co-factors and substrates, containing 13 NH 3 , is pumped over the enzyme column. The unreacted 13 NH 3 is separated from 13 N-NAD by on-line passage over a cation exchanger. After passing over a millipore filter, a sterile solution of radiochemically pure 13 N-NAD is obtained, containing 70 mCi in 10 mL. The total synthesis time is 10 minutes. The specific activity is about 120 mCi/μmol at EOB. Quality control includes sterility and pyrogen tests, HPLC and HPTLC analysis. (author)

Cereal bioengineering: Amylopectin-free and hyper-phosphorylated barley starch

DEFF Research Database (Denmark)

Carciofi, Massimiliano; Shaik, Shahnoor Sultana; Jensen, Susanne Langgård

Barley lines producing grains with either amylopectin-free or hyper-phosphorylated starches were made by transgenic methods. Cereals producing these kind of starches have not been reported before. Amylopectin-free barley was generated by simultaneously silencing the three genes encoding the starch...... and T1) of transgenic grains was tenfold higher than from vector control and wild type grains. Amylose content was not affected in hyper-phosphorylated grains. Hyper-phosphorylated starch granules had several pores on the surfaces, similar to pores seen on enzymatically semi-degraded granules...

Cereal bioengineering: Amylopectin-free and hyper-phosphorylated barley starch

DEFF Research Database (Denmark)

Carciofi, Massimiliano; Shaik, Shahnoor Sultana; Jensen, Susanne Langgård

2011-01-01

Barley lines producing grains with either amylopectin-free or hyper-phosphorylated starches were made by transgenic methods. Cereals producing these kind of starches have not been reported before. Amylopectin-free barley was generated by simultaneously silencing the three genes encoding the starch...... and T1) of transgenic grains was tenfold higher than from vector control and wild type grains. Amylose content was not affected in hyper-phosphorylated grains. Hyper-phosphorylated starch granules had several pores on the surfaces, similar to pores seen on enzymatically semi-degraded granules...

Selection of bacteria with hydrocarbon degrading capacity isolated from Colombian Caribbean sediments

International Nuclear Information System (INIS)

Narvaez Florez, Silvia; Gomez, Martha L; Martinez Maria M

2008-01-01

Thirty one bacterial isolations in minimal salts supplemented medium with hydrocarbons (ACPM or crude oil) as sole carbon source were isolated from sediment samples from the Colombian Caribbean. Bacterial strains underwent selection tests in different concentrations of hydrocarbons; 11 tolerant crude oil and ACPM strains in a range of 1-8%v/v were chosen. A mixed bacterial culture was created and assessed its ability to degrade hydrocarbons in a laboratory-scale test, with a concentration of 2% v/v of ACPM over a period of 21 days. Measurements of biomass in Colony Forming Units (CFU)/mL were used to develop the growth curve of the mixed culture. Hydrocarbons remotion was measured by mass chromatography. The mixed culture was able to degrade the 68.6% of aliphatic hydrocarbons in preference of long chain n- alkenes (C12- C31), reaching a maximum growth of 3.13 x 10 9 UFC / mL. Degradation of aromatic hydrocarbons was not evidenced under the observation time. Nine of the eleven strains were identified using the biochemical systems BBL and API 50 CHB/E; they belonged to the genus Klebsiella, Chromobacterium, Flavimonas, Enterobacter,Pseudomonas, and Bacillus. The evaluated strains have enzymatic potential to degrade hydrocarbons and it is necessary to characterize them at molecular level in order to develop and effective consortium for field application

Enzymatic biosensors based on the use of metal oxide nanoparticles

International Nuclear Information System (INIS)

Shi, Xinhao; Gu, Wei; Li, Bingyu; Chen, Ningning; Zhao, Kai; Xian, Yuezhong

2014-01-01

Over the past decades, various techniques have been developed to obtain materials at a nanoscale level to design biosensors with high sensitivity, selectivity and efficiency. Metal oxide nanoparticles (MONPs) are of particular interests and have received much attention because of their unique physical, chemical and catalytic properties. This review summarizes the progress made in enzymatic biosensors based on the use of MONPs. Synthetic methods, strategies for immobilization, and the functions of MONPs in enzymatic biosensing systems are reviewed and discussed. The article is subdivided into sections on enzymatic biosensors based on (a) zinc oxide nanoparticles, (b) titanium oxide nanoparticles, (c) iron oxide nanoparticles, and (d) other metal oxide nanoparticles. While substantial advances have been made in MONPs-based enzymatic biosensors, their applications to real samples still lie ahead because issues such as reproducibility and sensor stability have to be solved. (author)

Cellular automata modeling depicts degradation of cellulosic material by a cellulase system with single-molecule resolution.

Science.gov (United States)

Eibinger, Manuel; Zahel, Thomas; Ganner, Thomas; Plank, Harald; Nidetzky, Bernd

2016-01-01

Enzymatic hydrolysis of cellulose involves the spatiotemporally correlated action of distinct polysaccharide chain cleaving activities confined to the surface of an insoluble substrate. Because cellulases differ in preference for attacking crystalline compared to amorphous cellulose, the spatial distribution of structural order across the cellulose surface imposes additional constraints on the dynamic interplay between the enzymes. Reconstruction of total system behavior from single-molecule activity parameters is a longstanding key goal in the field. We have developed a stochastic, cellular automata-based modeling approach to describe degradation of cellulosic material by a cellulase system at single-molecule resolution. Substrate morphology was modeled to represent the amorphous and crystalline phases as well as the different spatial orientations of the polysaccharide chains. The enzyme system model consisted of an internally chain-cleaving endoglucanase (EG) as well as two processively acting, reducing and non-reducing chain end-cleaving cellobiohydrolases (CBHs). Substrate preference (amorphous: EG, CBH II; crystalline: CBH I) and characteristic frequencies for chain cleavage, processive movement, and dissociation were assigned from biochemical data. Once adsorbed, enzymes were allowed to reach surface-exposed substrate sites through "random-walk" lateral diffusion or processive motion. Simulations revealed that slow dissociation of processive enzymes at obstacles obstructing further movement resulted in local jamming of the cellulases, with consequent delay in the degradation of the surface area affected. Exploiting validation against evidence from atomic force microscopy imaging as a unique opportunity opened up by the modeling approach, we show that spatiotemporal characteristics of cellulose surface degradation by the system of synergizing cellulases were reproduced quantitatively at the nanometer resolution of the experimental data. This in turn gave

Optimization of enzymatic clarification of green asparagus juice using response surface methodology.

Science.gov (United States)

Chen, Xuehong; Xu, Feng; Qin, Weidong; Ma, Lihua; Zheng, Yonghua

2012-06-01

Enzymatic clarification conditions for green asparagus juice were optimized by using response surface methodology (RSM). The asparagus juice was treated with pectinase at different temperatures (35 °C-45 °C), pH values (4.00-5.00), and enzyme concentrations (0.6-1.8 v/v%). The effects of enzymatic treatment on juice clarity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity were investigated by employing a 3-factor central composite design coupled with RSM. According to response surface analysis, the optimal enzymatic treatment condition was pectinase concentration of 1.45%, incubation temperature of 40.56 °C and pH of 4.43. The clarity, juice yield, and soluble solid contents in asparagus juice were significantly increased by enzymatic treatment at the optimal conditions. DPPH radical-scavenging capacity was maintained at the level close to that of raw asparagus juice. These results indicated that enzymatic treatment could be a useful technique for producing green asparagus juice with high clarity and high-antioxidant activity. Treatment with 1.45% pectinase at 40.56 ° C, pH 4.43, significantly increased the clarity and yield of asparagus juice. In addition, enzymatic treatment maintained antioxidant activity. Thus, enzymatic treatment has the potential for industrial asparagus juice clarification. © 2012 Institute of Food Technologists®

Selective degradation of the recalcitrant cell wall of Scenedesmus quadricauda CASA CC202.

Science.gov (United States)

Reshma, Ragini; Arumugam, Muthu

2017-10-01

An eco-friendly cell wall digestion strategy was developed to enhance the availability of nutritionally important bio molecules of edible microalgae and exploit them for cloning, transformation, and expression of therapeutic proteins. Microalgae are the source for many nutritionally important bioactive compounds and potential drugs. Even though edible microalgae are rich in nutraceutical, bioavailability of all these molecules is very less due to their rigid recalcitrant cell wall. For example, the cell wall of Scenedesmus quadricauda CASA CC202 is made up of three layers comprising of rigid outer pectin and inner cellulosic layer separated by a thin middle layer. In the present investigation, a comprehensive method has been developed for the selective degradation of S. quadricauda CASA CC202 cell wall, by employing both mechanical and enzymatic treatments. The efficiency of cell wall removal was evaluated by measuring total reducing sugar (TRS), tannic acid-ferric chloride staining, calcoflour white staining, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) analysis. It was confirmed that the yield of TRS increased from 129.82 mg/g in 14 h from pectinase treatment alone to 352.44 mg/g by combined sonication and enzymatic treatment within 12 h. As a result, the combination method was found to be effective for the selective degradation of S. quadricauda CASA CC202 cell wall. This study will form a base for our future works, where this will help to enhance the digestibility and availability of nutraceutically important proteins.

Homeostatic maintenance via degradation and repair of elastic fibers under tension

Science.gov (United States)

Alves, Calebe; Araújo, Ascanio D.; Oliveira, Cláudio L. N.; Imsirovic, Jasmin; Bartolák-Suki, Erzsébet; Andrade, José S.; Suki, Béla

2016-06-01

Cellular maintenance of the extracellular matrix requires an effective regulation that balances enzymatic degradation with the repair of collagen fibrils and fibers. Here, we investigate the long-term maintenance of elastic fibers under tension combined with diffusion of general degradative and regenerative particles associated with digestion and repair processes. Computational results show that homeostatic fiber stiffness can be achieved by assuming that cells periodically probe fiber stiffness to adjust the production and release of degradative and regenerative particles. However, this mechanism is unable to maintain a homogeneous fiber. To account for axial homogeneity, we introduce a robust control mechanism that is locally governed by how the binding affinity of particles is modulated by mechanical forces applied to the ends of the fiber. This model predicts diameter variations along the fiber that are in agreement with the axial distribution of collagen fibril diameters obtained from scanning electron microscopic images of normal rat thoracic aorta. The model predictions match the experiments only when the applied force on the fiber is in the range where the variance of local stiffness along the fiber takes a minimum value. Our model thus predicts that the biophysical properties of the fibers play an important role in the long-term regulatory maintenance of these fibers.

Quantitative characterization of the formation of an interpenetrating phase composite in polystyrene from the percolation of multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Kota, Arun K; Cipriano, Bani H; Powell, Dan; Raghavan, Srinivasa R; Bruck, Hugh A

2007-01-01

For the first time, an interpenetrating phase polymer nanocomposite formed by the percolation of multiwalled carbon nanotubes (MWCNTs) in polystyrene (PS) has been quantitatively characterized through electrical conductivity measurements and melt rheology. Both sets of measurements, in conjunction with scanning electron microscopy (SEM) images, indicate the presence of a continuous phase of percolated MWCNTs appearing at particle concentrations exceeding 2 vol% MWCNTs in PS. To quantify the amount of this continuous phase present in the PS/MWCNT composite, electrical conductivity data at various MWCNT concentrations, β, are correlated with a proposed degree of percolation, C-bar(β), developed using a conventional power-law formula with and without a percolation threshold. To quantify the properties of the interpenetrating phase polymer nanocomposite, the PS/MWCNT composite is treated as a combination of two phases: a continuous phase consisting of a pseudo-solid-like network of percolated MWCNTs, and a continuous PS phase reinforced by non-interacting MWCNTs. The proposed degree of percolation is used to quantify the distribution of MWCNTs among the phases, and is then used in a rule-of-mixtures formulation for the storage modulus, G'(β, C-bar(β), ω), and the loss modulus, G''(β, C-bar(β), ω), to quantify the properties of the continuous phase consisting of percolated MWCNTs and the continuous PS phase reinforced by non-interacting MWCNTs from the experimental melt rheology data. The properties of the continuous phase of percolated MWCNTs are indicative of a scaffold-like microstructure exhibiting an elastic behavior with a complex modulus of 360 kPa at lower frequencies and viscoplastic behavior with a complex viscosity of 6 kPa s rad -1 at higher frequencies, most likely due to a stick-slip friction mechanism at the interface of the percolated MWCNTs. Additional evidence of this microstructure was obtained via scanning electron microscopy. This research

Production of MAG via enzymatic glycerolysis

Science.gov (United States)

Jamlus, Norul Naziraa Ahmad; Derawi, Darfizzi; Salimon, Jumat

2015-09-01

Enzymatic glycerolysis of a medium chain methyl ester, methyl laurate was performed using lipase Candida antarctica (Novozyme 435) for 6 hours at 55°C. The percentage of components mixture of product were determined by using gas chromatography technique. The enzymatic reaction was successfully produced monolaurin (45.9 %), dilaurin (47.1 %) and trilaurin (7.0 %) respectively. Thin layer chromatography (TLC) plate also showed a good separation of component spots. Fourier transformation infra-red (FTIR) spectrum showed the presence of ester carbonyl at wavenumber 1739.99 cm-1 and hydrogen bonded O-H at 3512.03 cm-1. The product is potentially to be used as emulsifier and additive in food industry, pharmaceutical, as well as antibacterial.

Semi-Markov processes

CERN Document Server

Grabski

2014-01-01

Semi-Markov Processes: Applications in System Reliability and Maintenance is a modern view of discrete state space and continuous time semi-Markov processes and their applications in reliability and maintenance. The book explains how to construct semi-Markov models and discusses the different reliability parameters and characteristics that can be obtained from those models. The book is a useful resource for mathematicians, engineering practitioners, and PhD and MSc students who want to understand the basic concepts and results of semi-Markov process theory. Clearly defines the properties and

Degradation of ethyl mercaptan and its major intermediate diethyl disulfide by Pseudomonas sp. strain WL2.

Science.gov (United States)

Wang, Xiangqian; Wu, Chao; Liu, Nan; Li, Sujing; Li, Wei; Chen, Jianmeng; Chen, Dongzhi

2015-04-01

A Pseudomonas sp. strain WL2 that is able to efficiently metabolize ethyl mercaptan (EM) into diethyl disulfide (DEDS) through enzymatic oxidation was isolated from the activated sludge of a pharmaceutical wastewater plant. One hundred percent removal of 113.5 mg L(-1) EM and 110.3 mg L(-1) DEDS were obtained within 14 and 32 h, respectively. A putative EM degradation pathway that involved the catabolism via DEDS was proposed, which indicated DEDS were further mineralized into carbon dioxide (CO2), bacterial cells, and sulfate (SO4 (2-)) through the transformation of element sulfur and ethyl aldehyde. Degradation kinetics for EM and DEDS with different initial concentrations by strain WL2 were evaluated using Haldane-Andrews model with maximum specific degradation rates of 3.13 and 1.33 g g(-1) h(-1), respectively, and maximum degradation rate constants of 0.522 and 0.175 h(-1) using pseudo-first-order kinetic model were obtained. Results obtained that aerobic degradation of EM by strain WL2 was more efficient than those from previous studies. Substrate range studies of strain WL2 demonstrated its ability to degrade several mercaptans, disulfides, aldehydes, and methanol. All the results obtained highlight the potential of strain WL2 for the use in the biodegradation of volatile organic sulfur compounds (VOSCs).

Lignosulfonate and elevated pH can enhance enzymatic saccharification of lignocelluloses

Directory of Open Access Journals (Sweden)

Wang ZJ

2013-01-01

Full Text Available Abstract Background Nonspecific (nonproductive binding (adsorption of cellulase by lignin has been identified as a key barrier to reduce cellulase loading for economical sugar and biofuel production from lignocellulosic biomass. Sulfite Pretreatment to Overcome Recalcitrance of Lignocelluloses (SPORL is a relatively new process, but demonstrated robust performance for sugar and biofuel production from woody biomass especially softwoods in terms of yields and energy efficiencies. This study demonstrated the role of lignin sulfonation in enhancing enzymatic saccharification of lignocelluloses – lignosulfonate from SPORL can improve enzymatic hydrolysis of lignocelluloses, contrary to the conventional belief that lignin inhibits enzymatic hydrolysis due to nonspecific binding of cellulase. Results The study found that lignosulfonate from SPORL pretreatment and from a commercial source inhibits enzymatic hydrolysis of pure cellulosic substrates at low concentrations due to nonspecific binding of cellulase. Surprisingly, the reduction in enzymatic saccharification efficiency of a lignocellulosic substrate was fully recovered as the concentrations of these two lignosulfonates increased. We hypothesize that lignosulfonate serves as a surfactant to enhance enzymatic hydrolysis at higher concentrations and that this enhancement offsets its inhibitive effect from nonspecific binding of cellulase, when lignosulfonate is applied to lignocellulosic solid substrates. Lignosulfonate can block nonspecific binding of cellulase by bound lignin on the solid substrates, in the same manner as a nonionic surfactant, to significantly enhance enzymatic saccharification. This enhancement is linearly proportional to the amount of lignosulfonate applied which is very important to practical applications. For a SPORL-pretreated lodgepole pine solid, 90% cellulose saccharification was achieved at cellulase loading of 13 FPU/g glucan with the application of its

Enzymatic saccharification and bioethanol production from Cynara cardunculus pretreated by steam explosion.

Science.gov (United States)

Fernandes, Maria C; Ferro, Miguel D; Paulino, Ana F C; Mendes, Joana A S; Gravitis, Janis; Evtuguin, Dmitry V; Xavier, Ana M R B

2015-06-01

The correct choice of the specific lignocellulosic biomass pretreatment allows obtaining high biomass conversions for biorefinery implementations and cellulosic bioethanol production from renewable resources. Cynara cardunculus (cardoon) pretreated by steam explosion (SE) was involved in second-generation bioethanol production using separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF) processes. Steam explosion pretreatment led to partial solubilisation of hemicelluloses and increased the accessibility of residual polysaccharides towards enzymatic hydrolysis revealing 64% of sugars yield against 11% from untreated plant material. Alkaline extraction after SE pretreatment of cardoon (CSEOH) promoted partial removal of degraded lignin, tannins, extractives and hemicelluloses thus allowing to double glucose concentration upon saccharification step. Bioethanol fermentation in SSF mode was faster than SHF process providing the best results: ethanol concentration 18.7 g L(-1), fermentation efficiency of 66.6% and a yield of 26.6g ethanol/100 g CSEOH or 10.1 g ethanol/100 g untreated cardoon. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cathepsin B-sensitive polymers for compartment-specific degradation and nucleic acid release.

Science.gov (United States)

Chu, David S H; Johnson, Russell N; Pun, Suzie H

2012-02-10

Degradable cationic polymers are desirable for in vivo nucleic acid delivery because they offer significantly decreased toxicity over non-degradable counterparts. Peptide linkers provide chemical stability and high specificity for particular endopeptidases but have not been extensively studied for nucleic acid delivery applications. In this work, enzymatically degradable peptide-HPMA copolymers were synthesized by RAFT polymerization of HPMA with methacrylamido-terminated peptide macromonomers, resulting in polymers with low polydispersity and near quantitative incorporation of peptides. Three peptide-HPMA copolymers were evaluated: (i) pHCathK(10), containing peptides composed of the linker phe-lys-phe-leu (FKFL), a substrate of the endosomal/lysosomal endopeptidase cathepsin B, connected to oligo-(L)-lysine for nucleic acid binding, (ii) pHCath(D)K(10), containing the FKFL linker with oligo-(D)-lysine, and (iii) pH(D)Cath(D)K(10), containing all (D) amino acids. Cathepsin B degraded copolymers pHCathK(10) and pHCath(D)K(10) within 1 h while no degradation of pH(D)Cath(D)K(10) was observed. Polyplexes formed with pHCathK(10) copolymers show DNA release by 4 h of treatment with cathepsin B; comparatively, polyplexes formed with pHCath(D)K(10) and pH(D)Cath(D)K(10) show no DNA release within 8 h. Transfection efficiency in HeLa and NIH/3T3 cells were comparable between the copolymers but pHCathK(10) was less toxic. This work demonstrates the successful application of peptide linkers for degradable cationic polymers and DNA release. Copyright © 2011 Elsevier B.V. All rights reserved.