Dimethylformamide Concentration Research Articles

Flexible Supercapacitor with Wide Electrochemical Stable Window Based on Hydrogel Electrolyte.

Hydrogel electrolyte can endow supercapacitors with excellent flexibility, which has developed rapidly in recent years. However, the water-rich structures of hydrogel electrolyte are easy to freeze at subfreezing and dry at high temperatures, which will affect its energy storage characteristics. The low energy density of micro supercapacitors also hinders their development. Herein, a strategy is proposed to reduce the free water activity in the hydrogel to improve the operating voltage and the energy density of the device, which is achieved through the synergistic effect of the hydrogel skeleton, N, N'-dimethylformamide (DMF), NaClO4 and water. High concentrations of DMF and NaClO4 are introduced into sodium alginate/polyacrylamide (SA/PAAM) hydrogel through solvent exchange to obtain SA/PAAM/DMF/NaClO4 hydrogel electrolyte, which exhibited a high ionic conductivity of 82.1 mS cm-1, a high breaking strength of 563.2kPa, and a wide voltage stability window of 3.5V. The supercapacitor devices are assembled by the process of direct adhesion of the hydrogel electrolyte and laser induced graphene (LIG). The micro-supercapacitor exhibited an operating voltage of 2.0V, with a specific capacitance of 2.41 mF cm-2 and a high energy density of 1.34 µWh cm-2, and it also exhibit a high cycle stability, good flexibility, and integration performance.

Fabrication and characterization of C3N4 coating by electrochemical deposition on stainless steel

In this study, C3N4 coating was successfully fabricated on AISI 304 stainless steel by electrochemical deposition method using N-N dimethylformamide (DMF) and KCl as the electrolyte. The influences of DMF concentration on the microstructure, hardness, and wear resistance of the coatings were investigated by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Vickers hardness tester, and pin-on-disk wear tester. The results indicate that a continue C3N4 coating layer can be formed on the steel surface. Compared to the untreated sample, the surface hardness and wear resistance of the stainless steel can be improved apparently after depositing of C3N4 coating. The hardness and wear resistance of the coatings increase firstly and then decrease with increase of DMF concentration. The coatings fabricated with 50 % DMF possess the highest hardness of 1329 HV0.05 and the lowest friction coefficient of 0.35 at 5 N. The main wear mechanisms are fatigue wear, abrasive wear, and oxidative wear. Deposition of C3N4 coating conforms to the polarization-adsorption-electrochemical reaction mechanism in the present investigation conditions.

Comparison between Electrooxidation of 1-Naphthol and 2-Naphthol in Different Non-Aqueous Solvents and Suppression of Layer Growth of Polymers

The two naphthol isomers were investigated in different organic solvents by taking cyclic voltammograms, and fouling took place on a platinum electrode surface, except for dimethyl sulfoxide and dimethyl formamide. Studies in allyl alcohol rarely used in electrochemical investigations pointed to the importance of the carbon–carbon double bond as electrode deactivation was remarkably faster compared with its saturated analog solvent. Similarly, the use of the other unsaturated solvent mesityl oxide in the electropolymerization of naphthols resulted in different findings compared with methyl isobutyl ketone. As dimethyl formamide was the best choice concerning the solubility of products, it was successfully tested in electrode renewal after deactivation in an aqueous solution. The increase in dimethyl formamide content led to more and more improved reproducibility of the currents of the outlined aromatic compounds. Naphthol isomers were assessed in the suppression of layer growth originating from the electrooxidation of another monomer phloroglucinol. Its simultaneous electrooxidation with naphthol monomers had a dramatic effect on layer morphology and it was found that instead of a coherent organic layer originating from the homopolymerization of phloroglucinol, the copolymerization with naphthols led to the development of more porous and rougher deposits. The suppressed electropolymerization thus increased sensitivity towards a chosen redox active compound, 4-methoxyphenol.

Transitioning from a research protocol to a scalable applied pathway for Xenopus laevis sperm cryopreservation at a national stock center: The effect of cryoprotectants.

Sperm cryopreservation is a critical tool for safeguarding and managing valuable genetic resources. Protocols for cryopreservation of Xenopus laevis sperm were available but lacking sperm quality evaluation and scalability and the outcomes were inconsistent. The goal of this study was to begin developing a center-level cryopreservation pathway for this species by integrating French straws as containers that would facilitate germplasm repository development. The objectives were to analyze the effect of: (1) three sperm concentrations (33, 50, and 100 × 106 sperm/mL) on post-thaw fertilization, (2) three final concentrations (2.5%, 5%, and 10%) of dimethyl sulfoxide, methanol, and dimethylformamide (DMFA) on sperm membrane integrity of fresh and frozen samples, (3) two concentrations (5% and 10%) of DMFA with and without 5% sucrose at four cooling rates (5, 10, 20, and 40°C/min) on sperm membrane integrity and motility, and (4) egg exposure to different concentrations of DMFA on fertilization. Few differences in sperm viability were found among fresh samples incubated in cryoprotectants, but thawed samples frozen in methanol or DMFA presented higher membrane integrity. Samples frozen in 10%DMFA at 20°C/min showed higher membrane integrity (60 ± 7%) than other DMFA concentrations and cooling rates, and the same total motility (30 ± 7%) as at 10°C/min. Higher DMFA concentrations (10%-13%) were detrimental for embryo development compared to lower concentrations (<6%). This study provided a reliable protocol for sperm cryopreservation in Xenopus laevis to yield an application pathway with potential for high throughput that can be used as a roadmap for work with other species.

Dimethylformamide Impurities as Propylene Polymerization Inhibitor.

This research study examined how the use of dimethylformamide (DMF) as an inhibitor affects the propylene polymerization process when using a Ziegler-Natta catalyst. Several experiments were carried out using TiCl4/MgCl2 as a catalyst, aluminum trialkyl as a cocatalyst, and different amounts of DMF. Then, we analyzed how DMF influences other aspects of the process, such as catalyst activity, molecular weight, and the number of branches in the polymer chains obtained, using experimental and computational methods. The results revealed that as the DMF/Ti ratio increases, the catalyst activity decreases. From a concentration of 5.11 ppm of DMF, a decrease in catalyst activity was observed, ranging from 45 TM/Kg to 44 TM/Kg. When the DMF concentration was increased to 40.23 ppm, the catalyst activity decreased to 43 TM/Kg, and with 75.32 ppm, it dropped even further to 39 TM/Kg. The highest concentration of DMF evaluated, 89.92 ppm, resulted in a catalyst productivity of 36.5 TM/Kg and lost productivity of 22%. In addition, significant changes in the polymer's melt flow index (MFI) were noted as the DMF concentration increased. When 89.92 ppm of DMF was added, the MFI loss was 75%, indicating a higher flowability of the polymer. In this study, it was found that dimethylformamide (DMF) exhibits a strong affinity for the titanium center of a Ziegler-Natta (ZN) catalyst, with an adsorption energy (Ead) of approximately -46.157 kcal/mol, indicating a robust interaction. This affinity is significantly higher compared to propylene, which has an Ead of approximately -5.2 kcal/mol. The study also revealed that the energy gap between the highest occupied molecular orbital (HOMO) of DMF and the lowest unoccupied molecular orbital (SOMO) of the Ziegler-Natta (ZN) catalyst is energetically favorable, with a value of approximately 0.311 eV.

Efficient bioremediation of laboratory wastewater co-contaminated with PAHs and dimethylformamide by a methylotrophic enrichment culture

A methylotrophic enrichment culture, MM34X, has been assessed for its exceptional ability in biodegradation of dimethylformamide (DMF) and bioremediation of laboratory wastewater (LWW) co-contaminated with polycyclic aromatic hydrocarbons (PAHs). The culture MM34X tolerated high concentrations of DMF and efficiently degraded 98% of 20,000 mg L−1 DMF within 120 h. LWW bioremediation was performed in stirred bottle laboratory-scale bioreactor. After 35 days of incubation, 2760.8 ± 21.1 mg L−1 DMF, 131.8 ± 9.7 mg L−1 phenanthrene, 177.3 ± 7.5 mg L−1 pyrene and 39.5 ± 2.7 mg L−1 BaP in LWW were removed. Analysis of post-bioremediation residues indicated the absence of any known toxic intermediates. The efficacy of bioremediation was further evaluated through cyto-genotoxicity assays using Allium cepa. The roots of A. cepa exposed to bioremediated LWW showed improved mitotic index, whereas original LWW completely arrested cell growth. Similarly, the alkaline comet assay indicated alleviation of genotoxicity in bioremediated LWW, as evidenced by significantly lower DNA damage in terms of tail DNA and Olive tail moment. In addition, oxidative stress assays, performed using fluorescent probes 2′,7′-dichlorodihydrofluorescein diacetate, C11-BODIPY and dihydrorhodamine 123, revealed significant mitigation of oxidative stress potential in bioremediated LWW. Our findings suggest that the enrichment MM34X may prime the development of inexpensive and efficient large-scale bioremediation of LWW co-contaminated with PAHs and DMF.

Effects of D-lactide content and molecular weight on the morphological, thermal, and mechanical properties of electrospun nanofiber polylactide mats

In this study, the effects of both D-lactide content, that is, the change in PLA crystallizability, and molecular weight of polylactide (PLA) on its electrospinning behavior, along with thermal and mechanical properties of the electrospun mats were investigated. Although the effect of D-lactide content on processability of PLA has been studied in extrusion, thermoforming, foaming, and melt spinning, it has not been explored in electrospinning. The current study aimed to analyze electrospinnability of three different PLA grades; two amorphous with high and low molecular weights (i.e., aPLA-H and aPLA-L) and a semicrystalline with a high molecular weight (cPLA-H). PLAs were dissolved at different concentrations in chloroform (CHL)/dimethylformamide (DMF) at various volume ratios. Due to its high crystallizability and molecular weight, coarser nanofibers of cPLA-H were produced from solvents with high CHL content (≥75%), resulting in highest water vapor transmission rate (50,000 g/m2.day) of mats. aPLA-H revealed coarser nanofibers than that of aPLA-L due to its higher molecular entanglement. Although the increase in DMF content in the solvent hindered dissolving and electrospinning of cPLA-H, it caused the refinement of nanofibers in amorphous PLAs. Despite similar tensile strength, cPLA-H showed higher elongation at break (∼69%) than that of aPLA-H (∼59%) possibly due to the existence of some beads within the fibers in aPLA-H. Storage modulus of electrospun cPLA-H was also higher (∼15MPa) than that of other samples (∼10–12 MPa) due to high content of crystallinity (∼37%) while aPLA-L revealed the lowest storage modulus (∼10MPa) due to its amorphous structure and low molecular entanglement.

Effect of Dimethyl Formamide (DMF) on Vanadium Reloading Over V-Ti SCR Catalyst

Active components reloading is critical process for the catalyst regeneration, which is limited by the low adsorption capacity and unwilling distribution of desired components to the catalyst surface. Herein we demonstrated that with dimethyl formamide(DMF) modification and sequentially reloading of vanadium, the traditional V-Ti SCR catalyst, which uses vanadium as the active components and titanium as the carrier, showed the significantly improved DeNOx performance, owing to the increased adsorption capacity and desired distribution of vanadium. When the DMF concentration was 6%, the adsorption capacity of the promoted catalyst was 3.58 and 6.57 mg/g under vanadyl ion concentrations of 1.5 and 3 g/L, respectively, 135 and 147% higher than that of the original catalyst. Adsorption kinetics demonstrated that the pseudo-second-order kinetic model better describes the process by which vanadyl ions adsorb onto the catalyst. In addition, the adsorption equilibrium indicated that Langmuir model was a closer fit for the vanadyl ion adsorption to the promoted catalyst. After DMF modification, the vanadyl ions were first adsorbed onto the functional groups on the catalyst surface, substantially increasing the vanadium loading on the catalyst surface while limiting the increase in vanadium content within the interior of catalyst, which was conducive to enhancing the DeNOx activity and reducing the increase in the SO2/SO3 conversion. When the vanadium adsorption capacity was 3.5 mg/g, the increase in the DeNOx activity of the promoted catalyst was 68.1% higher than that of the original catalyst, whereas the increase in SO2/SO3 conversion was 28.9% lower than that of the original catalyst. Thus, in the regeneration of SCR catalysts vanadium initial concentration and loading could be reduced.

Polyacrylonitrile-based electrolytes: How processing and residual solvent affect ion transport and stability

Polyacrylonitrile (PAN) is one of the alternative candidate polymer hosts to form solid polymer electrolytes (SPEs) besides the widely used poly(ethylene oxide). In this study, we systematically investigate the processing of PAN based SPEs containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, using dimethylformamide (DMF) as the solvent. The effects of PAN processing procedure including solution mixing, casting, and drying on the morphology, ion transport, solvation structure, Li and oxidative stability of PAN electrolytes are thoroughly examined. In particular, four drying conditions are investigated and the amount of residual DMF is accurately determined using infrared (IR) spectroscopy. Varying the drying conditions can lead to five orders of magnitude decrease in the ionic conductivity. As DMF content decreases, the SPE's stability again Li metal dramatically improves. The practical oxidative stability is also strongly affected by the residual DMF content, ranging from 2.5 V to 3.5 V, much lower than reported values. Finally, the role of the residual DMF solvent is elucidated. DMF content vitally influences ion solvation structure at different concentration regimes, which ultimately dictates the ion conduction mechanism and oxidative stability of PAN based SPEs. This thorough study lays the groundwork for future development of PAN based electrolytes.

Effect of different structure of membrane support on polyamide formation and its performance in reverse osmosis

This work aims to investigate the polyamide (PA) morphology on polysulfone (PSf) membrane supports with different morphologies. It was achieved by systematically varying the N-Methyl-2-Pyrrolidone (NMP) and Dimethylformamide (DMF) solvent composition ratios in dope solution as adapted in Tiraferri et al. The PSf membrane support was firstly synthesized via phase separation technique. Next, the PA layer of the thin film composite (TFC) membrane was synthesized via consistent interfacial polymerization parameters on the PSf membrane support. The PA layer over the resulting array of membrane supports was investigated on their surface wettability, top and cross-sectional morphologies, and performances. Result shows that with more NMP content in the dope solution produces thin and dense sponge-like top skin layer with intense extended finger-like macrovoids sublayer. Meanwhile, more DMF content in the dope solution produces thicker and dense sponge-like morphology on the top skin with finger-like pores underneath. A layer of smaller and loosen ridge-and-valley PA structures is formed on the thicker and dense sponge-like morphology. TFC membrane over support made of NMP to DMF (40:60) was observed had the highest hydrophilicity with the lowest contact angle measurement of 61.9 ± 3.1°. It also performed the highest water permeability of 4.06 LMH/bar, moderate salt rejection of 95.65% with salt permeability of 1.9 gMH.

Composite Ferroelectric Membranes Based on Vinylidene Fluoride-Tetrafluoroethylene Copolymer and Polyvinylpyrrolidone for Wound Healing.

Wound healing is a complex process and an ongoing challenge for modern medicine. Herein, we present the results of study of structure and properties of ferroelectric composite polymer membranes for wound healing. Membranes were fabricated by electrospinning from a solution of vinylidene fluoride/tetrafluoroethylene copolymer (VDF–TeFE) and polyvinylpyrrolidone (PVP) in dimethylformamide (DMF). The effects of the PVP content on the viscosity and conductivity of the spinning solution, DMF concentration, chemical composition, crystal structure, and conformation of VDF–TeFE macromolecules in the fabricated materials were studied. It was found that as PVP amount increased, the viscosity and conductivity of the spinning solutions decreased, resulting in thinner fibers. Using FTIR and XRD methods, it was shown that if the PVP content was lower than 50 wt %, the VDF–TeFE copolymer adopted a flat zigzag conformation (TTT conformation) and crystalline phases with ferroelectric properties were formed. Gas chromatography results indicated that an increase in the PVP concentration led to a higher residual amount of DMF in the material, causing cytotoxic effects on 3T3L1 fibroblasts. In vivo studies demonstrated that compared to classical gauze dressings impregnated with a solution of an antibacterial agent, ferroelectric composite membranes with 15 wt % PVP provided better conditions for the healing of purulent wounds.

Comparison of different cryoprotective agents on swamp buffalo semen cryopreservation

Present study aimed to determine the effectivenessof dimethylformamide (DMF)as cryoprotective agent (CPA) by determining its optimum concentration inTris Eggyolk (TEY) extender on the quality of post-thaw swamp buffalo semen. Only ejaculates having &gt; 60% sperm motility were divided into eight s tubes. Four tubes were diluted in TEY with 4, 5, 6, 7% of glycerol and four other tubes were diluted in TEY with 4, 5, 6, 7% of DMF. Diluted semen then packed into ministraw (0.25 mL), equilibrated at 4°C for 4 hours and freezed at 8 cm above liquid nitrogen vapour for 10 minutes and then stored at liquid nitrogencontainer. After 24 hours of storage, straws were thawed at 37°C for 30 seconds. The result showed that sperm motility after equilibration tend to be the same at all four glycerol concentrations, whereas the decrease in motility was highest in extenders with a DMF concentration of 7% (P &lt;0.05). Post-thaw sperm motility and recovery rate in TEY extender containing 5% DMF or 7% glycerol were highest (P&lt;0.05) than other glycerol or DMF concentration. Sperm viability and membrane integrity did not differ among TEY containing 6% or 7% glycerol, both were higher (P&lt;0.05) than 4% or 5% glycerol. Viability and membrane integrity of sperm in 5% DMF was superior (P&lt;0.05) to 4%, 6% or 7%. This research concluded that 5% DMF or 7% glycerol was considered to be the most suitable CPAs for swamp buffalo semen cryopreservation.

Mesorhizobium tamadayense MM3441: A novel methylotroph with a great potential in degrading N,N′-dimethylformamide

The widespread presence of the versatile solvent, N,N′-dimethylformamide (DMF), in industrial wastewaters, and the growing concern over its ecotoxicity necessitate the implementation of an effective remediation technology. Mesorhizobium tamadayense MM3441, isolated from a soil contaminated with polycyclic aromatic hydrocarbons, utilized higher concentrations of DMF as sole carbon and nitrogen source. To our knowledge, the strain MM3441 is the only member of the genus, Mesorhizobium, capable of degrading DMF. This strain, with methylotrophic mode of nutrition, also exhibited resistance to several organic solvents. Optimal growth of the strain was observed at pH 7.0 in the presence of 5000 mg L−1 DMF. The strain removed 95% of 5000 mg L−1 DMF within nine days of incubation. DMF utilization was accompanied by the accumulation of dimethylamine (DMA) and ammonia in the culture medium. Both the resting cell and dimethylformamidase (DMFase) assays provided the circumstantial evidence that DMF degradation by the strain MM3441 proceeds via the typical pathway yielding DMA. However, DMFase expression is not inducible with DMF, suggesting that the enzyme is constitutively expressed. Based on the DMF degradation ability and metabolic flexibility of the strain MM3441, the present study advocates its potential use in bioremediation of the environments contaminated with DMF.

The effects of dimethylformamide exposure on liver and kidney function in the elderly population: A cross-sectional study.

Dimethylformamide (DMF) is widely used as a solvent in the production of synthetic leather. Previous studies have focused on workers exposed to DMF in leather factories; however, little attention has been paid to the general population. This study was conducted to examine the effects of DMF exposure on elderly residents living near synthetic leather factories. A total of 962 subjects over 60 years of age in proximity to these factories (monitoring points) were enrolled as the exposure group, and 1924 permanent residents living distant from the factories were enrolled as the control group. The exposure group was divided into 3 groups according to their distance from the monitoring points. Physical examination, routine blood tests, and liver and renal function data were collected, and the DMF concentration in the air was analyzed by gas chromatography-mass spectroscopy. The prevalence of abnormal heart rhythm, electrocardiogram and B-mode ultrasound results in the exposure group was significantly greater than in the control group. Aspartate transaminase (AST), alanine transaminase (ALT), and blood urea nitrogen (BUN) levels in the exposure group also were higher than those in the control group (P < .01). There was an effect of distance from leather factories on liver and kidney dysfunction in the 3 exposure groups. Compared with the exposure group at >3 km distance from the source, the prevalence of increased AST, ALT, and BUN in the exposure group at <1 km was significantly greater (P < .001). It was concluded that DMF exposure was related to an increased risk of a cardiac injury and liver and kidney dysfunction.

Formation thermodynamic parameters of nano copper (II) acetate monohydrate with 4,6-diacetylresorcinol in mixed solvents

The formation thermodynamic parameters, formation constants (Kf), Gibbs free energies of formation (ΔGf), enthalpies of formation (ΔHf) and entropies of formation (ΔSf) of nano copper (II) acetate monohydrate with 4,6-diacetylresorcinol as a ligand in pure DMF and in mixed DMF - water solvents are measured in different concentrations of dimethylformamide - water mixed solvents (70% DMF, 80% DMF, 90% DMF and 100% DMF) at different temperatures, 293.15, 303.15, 313.15 and 323.15K. The data indicate that three types of complexes with metal to ligand ratios 1:2, 1:1 and 2:1 stoichiometric complexes are formed. A comparison between the thermodynamic parameters of formation for the three complexes is studied.

New chalcone-substituted metallophthalocyanines: Synthesis, characterization, and investigation of their properties

The synthesis of novel metallophthalocyanines (M = Zn, Mg, and Co) derived from ( E)-3-(3-bromophenyl)-1-(3-hydroxyphenyl)prop-2-en-1-one and ( E)-3-(3-fluorophenyl)-1-(3-hydroxyphenyl)prop-2-en-1-one is achieved. These complexes and the synthesized novel phthalonitrile derivatives are characterized by FTIR, 1H NMR, 13C NMR, UV-Vis, mass spectrometry, and elemental analysis. The aggregation properties of the metallophthalocyanines ZnPc, MgPc, and CoPc are investigated in different solvents and at different concentrations in dimethyl formamide. The electrochemical behavior is also investigated. The cyclic voltammograms give one oxidation reaction for all the bromo-derived metallophthalocyanines and one reduction reaction for all the fluoro-derived metallophthalocyanines. Fe3+, Cd2+, Hg2+, Cu2+, Ni2+, and Co2+ ions are titrated fluorometrically with the phthalocyanines. The bromo- and fluoro-substituted phthalocyanine compounds show different effects on the metal ion titrations.

Cryopreservation of Swamp Buffalo Semen in Skim Milk Yolk-based Diluent with Two Different Cryoprotectants

The successful of artificial insemination (AI) in buffalo is still low. The quality of frozen semen determines the successful of AI program. Glycerol is widely used for cryopreservation of buffalo semen with unsatisfactory results due to its toxicity and antifertility properties. This study aimed to investigate the effect of glycerol and dimethylformamide (DMF) concentrations in skim milk egg yolk (SMEY)–based diluent on the quality of frozen-thawed swamp buffalo bull semen. Fresh semen was divided into eight aliquots. Each aliquot was diluted in SMEY containing 4%, 5%, 6%, and 7% glycerol and 4%, 5%, 6%, and 7% DMF. Diluted semen was packed into mini straw (0.25 mL), equilibrated at 4 °C for 4 hours, frozen in liquid nitrogen vapor for 10 minutes, and stored at liquid nitrogen container. The straws were thawed after 24 hours at 37 °C for 30 seconds for evaluation. The results showed that the post thawed sperm motility and recovery rate in SMEY extender containing 7% glycerol and 5% DMF were higher than the other glycerol or DMF concentrations. Post thawed sperm viability and plasma membrane integrity in SMEY containing 4%-6% DMF did not differ significantly, however both values were higher than those in 7% DMF. Post thawed sperm viability and plasma membrane integrity did not differ between SMEY containing 6% and 7% glycerol. However, both values were higher than those in 4% and 5% glycerol. It is concluded that 7% glycerol or 5% DMF is considered to be the most suitable cryoprotective agent for swamp buffalo semen cryopreservation.The successful of artificial insemination (AI) in buffalo is still low. The quality of frozen semen determines the successful of AI program. Glycerol is widely used for cryopreservation of buffalo semen with unsatisfactory results due to its toxicity and antifertility properties. This study aimed to investigate the effect of glycerol and dimethylformamide (DMF) concentrations in skim milk egg yolk (SMEY)–based diluent on the quality of frozen-thawed swamp buffalo bull semen. Fresh semen was divided into eight aliquots. Each aliquot was diluted in SMEY containing 4%, 5%, 6%, and 7% glycerol and 4%, 5%, 6%, and 7% DMF. Diluted semen was packed into mini straw (0.25 mL), equilibrated at 4 °C for 4 hours, frozen in liquid nitrogen vapor for 10 minutes, and stored at liquid nitrogen container. The straws were thawed after 24 hours at 37 °C for 30 seconds for evaluation. The results showed that the post thawed sperm motility and recovery rate in SMEY extender containing 7% glycerol and 5% DMF were higher than the other glycerol or DMF concentrations. Post thawed sperm viability and plasma membrane integrity in SMEY containing 4%-6% DMF did not differ significantly, however both values were higher than those in 7% DMF. Post thawed sperm viability and plasma membrane integrity did not differ between SMEY containing 6% and 7% glycerol. However, both values were higher than those in 4% and 5% glycerol. It is concluded that 7% glycerol or 5% DMF is considered to be the most suitable cryoprotective agent for swamp buffalo semen cryopreservation.

Amides as cryoprotectants for the freezing of Brycon orbignyanus sperm

The objective of this study was to evaluate the use of different amides as an alternative for the cryopreservation of sperm from the endangered species, Bryconorbignyamus, an important fish for aquaculture in Brazil. The cryoprotectants which were combined with Beltsville Thawing Solution™ extender, each at the concentrations of 2.5%, 5%, 7.5%, and 10%, were as follows: (1) dimethylacetamide (DMA), (2) dimethylformamide (DMF), and (3) methylformamide (MF). The cyoprotectant methylglycol (MG, 10%) was used as a control group. Therefore, 13 treatment groups were performed. The sperm were diluted in each cryoprotectant, loaded into 0.25-mL straws, frozen in a nitrogen vapor vessel (dry shipper), and stored in liquid nitrogen at–196 °C. The following sperm-movement parameters were measured using CASA: total motility (TM), progressive motility (PM), curvilinear speed (VCL), rectilinear speed (VSL), average path velocity (VAP), curved line distance (DCL), straight line distance (DSL), average path distance (DAP), straightness (STR), linearity (LIN), wobble (WOB), cross beat frequency (BCF) and sperm movement duration (SMD). In order to assess DNA fragmentation index, lipid peroxidation, cell integrity, integrity of plasma membrane, membrane fluidity, mitochondrial functionality, and reactive oxygen species, flow cytometry was used. The best results were obtained with 7.5% DMF, among all the amides tested, with sperm motility (66%) significantly higher than the other cryoprotectants evaluated (P < .05). DMF (7.5%) exhibited higher velocities and distances, and lower ROS production and lipoperoxidation, in comparison to MG (P < .05). It also exhibited high membrane integrity (84.5%) and cell integrity (98.7%), and low membrane fluidity (20.3%) (P < .05). MG (10%) exhibited only 38% motility, lower mitochondrial protection (39.8%), and higher DNA fragmentation index (0.07), despite the high membrane integrity observed (85.6%). The DMF concentration of 7.5% demonstrated greater protection of sperm function and cellular structure, and is therefore recommended for the cryopreservation of B. orbignyamus spermatozoa.

Effects of aprotic solvents on the stability of metal-free superoxide dismutase probed by native electrospray ionization-ion mobility-mass spectrometry.

Considering that aprotic solvents are often used as cosolvents in investigating the interactions between small molecules and proteins, we assessed the effects of five aprotic solvents represented by dimethylformamide (DMF) on the structure stabilities of metal-free SOD1 (apo-SOD1) by native electrospray ionization-ion mobility-mass spectrometry (ESI-IM-MS). These aprotic solvents include DMF, 1,3-dimethyl-2-imidazolidinone (DMI), dimethyl sulfoxide (DMSO), acetonitrile (ACN), and tetrahydrofuran (THF). Results indicated that DMI, DMSO, and DMF at low percentage concentration could reduce the average charge and the dimer dissociation of apo-SOD1. By contrast, ACN and THF at low concentration have no similar effect. DMF was selected as a representative solvent to further investigate the detailed effects on the structure stability of apo-SOD1 by using collision-induced dissociation and unfolding. The results reveal that the addition of minimal DMF to an aqueous protein solution can protect against the unfolding and dissociation of dimer, even under destabilizing conditions (such as low pH or high cone voltage). When the different percentage concentrations of DMF were added, the average collision cross section of apo-SOD1 showed that apo-SOD1 became compacted when the DMF concentration increased from 0% to 1% and eventually started extending when increased from 1% to 20%. The results indicated that DMF has similar effects to DMSO in native mass spectrometry (MS) and it can also be used as a cosolvent besides DMSO in investigating the stabilities of proteins and the interactions between small molecules and proteins.

SEMICONDUCTOR GAS SENSORS FOR DETECTION OF CHEMICAL WARFARE AGENTS AND TOXIC INDUSTRIAL CHEMICALS

The sensors for detection of toxic and chemical warfare agents (CWA) should be sensitive to low concentrations of gases – considerably lower than ones immediately dangerous to life or health concentrations. The paper shortly discusses classical CWAs and toxic industrial sensors; makes a comparison between nuclear weapons and chemical agents and a toxicity comparison between real gases and simulants. Moreover, the paper analyzes the simulants for testing the sensor devices and semiconductor gas sensor' technique; shows sensitivity change with dimethyl methylphosphonate (DMMP) gas concentration for sensor made of SnO 2 . The MoO 3 , NiO, Al 2 O 3 , In 2 O 3 , Pt, ZnO and ZrO 2 additives are reported to exhibit enhanced sensitivity to dimethyl methylphosphonate (DMMP), and Al2O3, In2O3, ZrO 2 and ZnO additives – to exhibit enhanced sensitivity to dipropyleneglycol methylethylene (DPGME). SnO2 devices with ZrO 2 and ZnO additives exhibit high sensitivity to acetonitrile. The sensors made from Co-doped SnO 2 films demonstrate sensitivity to CWAs such as sarin and yperite. We performed the measurements at the operating temperature of 210 ºC, and found that the sensor exposed comparatively greater concentration of target gas (200 ppm sarin and 100 ppm yperite) and the SnO 2 &lt;Co&gt; sensor was sensitive to yperite starting from 25 ppm. Furthermore, the sensitivities to 50 ppm and 12.5 ppm sarin were found. The paper presents the results of our studies on tin oxide/ multiwall carbon nanotube film nanocomposite sensors of PG, dimethylformamide (DMF) and formaldehyde (FA) using hydrothermal synthesis and sol-gel methods. The investigations of response/recovery characteristics in the 50–300 o C operating temperature range reveal that the optimal operating temperature for the PG, DMF and FA vapor sensors, taking into account both high response and acceptable response and recovery times, was 200–220 ºC. A sensor response dependence on gas concentration in all cases was linear. We measured the minimal PG, DMF and FA gas concentrations at which the perceptible signal was registered.