Rational surface charge engineering of haloalkane dehalogenase for boosting the enzymatic performance in organic solvent solutions

Biocatalysis in organic solvents(OSs)has numerous important applications,but native enzymes in OSs often exhibit limited catalytic performance.Herein,we proposed a computation-aided surface charge engineering strategy to improve the catalytic performance of haloalkane dehalogenase DhaA in OSs based on the energetic analysis of substrate binding to the DhaA surface.Several variants with enhanced OS resistance were obtained by replacing negative charged residues on the surface with positive charged residue(Arg).Particularly,a four-substitution variant E16R/E93R/E121R/E257R exhibited the best catalytic performance(five-fold improvement in OS resistance and seven-fold half-life increase in 40%(vol)dimethylsulfoxide).As a result,the overall catalytic performance of the variant could be at least 26 times higher than the wild-type DhaA.Fluorescence spectroscopy and molecular dynamics simulation studies revealed that the residue substitution mainly enhanced OS resistance from four aspects:(a)improved the overall structural stability,(b)increased the hydrophobicity of the local microenvironment around the catalytic triad,(c)enriched the hydrophobic substrate around the enzyme molecule,and(d)lowered the contact frequency between OS molecules and the catalytic triad.Our findings validate that computationaided surface charge engineering is an effective and ingenious rational strategy for tailoring enzyme performance in OSs.

Rapid recovery of polycrystalline silicon from kerf loss slurry using double-layer organic solvent sedimentation method

The rapid development of photovoltaic （PV） industries has led to a shortage of silicon feedstock. However, more than 40% silicon goes into slurry wastes due to the kerf loss in the wafer slicing process. To effectively recycle polycrystalline silicon from the kerf loss slurry, an innovative double-layer organic solvent sedimentation process was presented in the paper. The sedimentation velocities of Si and SiC particles in some organic solvents were investigated. Considering the polarity, viscosity, and density of solvents, the chloroepoxy propane and carbon tetrachloride were selected to separate Si and SiC particles. It is found that Si and SiC particles in the slurry waste can be successfully separated by the double-layer organic solvent sedimentation method, which can greatly reduce the sedimentation time and improve the purity of obtained Si-rich and SiC-rich powders. The obtained Si-rich powders consist of 95.04% Si, and the cast Si ingot has 99.06% Si.

Organic Solvents Enhanced Spectrofluorimetric Method for Determination of Laccase Activity

A novel fluorimetric method for determination of laccase activity in organic solvents is proposed, based on the oxidation ofo-phenylenediamine (1,2-diaminobenzene, OPDA) catalyzed by laccase yielding 2,3-diaminophenazine. The optimal conditions for laccase in organic media areT=55°C, pH=6.5, 1.0×10?2mol/L OPDA, 1.25 mL ethanol, 1.25 mL 1,4-dioxane and 1.25 mL acetone. The linear range of the method proposed in ethanol, 1,4-dioxane and acetone media were 0.44–19.33, 0.11–20.85, 0.38–21.05 U with the detection limit of 0.088, 0.022, 0.076 U, respectively. The proposed method has been applied to the analysis of laccase activity of real samples with more accurate and sensitive than that of the previous method reported.

Investigation on Organic Solvent Free Toluene Oxidative Bromination Reaction Catalyzed by HTS Zeolite

The toluene oxidative bromination reaction catalyzed by hollow titanium silicalite(HTS)zeolite in aqueous medium was investigated by employing H2O2 and HBr under mild conditions without the need for organic solvent.A high toluene conversion(90.7%)and high selectivity of mono-bromotoluene(99.0%)was achieved under the optimal reaction conditions.The UV-Raman spectroscopy was applied for the mechanism study and the result reveals that HTS is efficient for catalyzing the oxidation reaction of HBr with H2O2 to produce abundant active bromine species,which can further facilitate the toluene electrophilic bromination reaction.A two-step toluene bromination reaction mechanism involving the HTS catalyzed active bromine species“generation-conversion-utilization”process is proposed based on the UV-Raman spectroscopy analysis.

Preparation of nanometer perovskite-type oxide La_(0.8)Sr_(0.2)MnO_3 by organic solvent sol-gel method and capability testing

A perovskite-type oxide, La0.8Sr0.2MnO3, was synthesized by the organic solvent sol-gel method. The desired metal cations were chelated in a solution by using citric acid as the chelating agent and absolute ethanol as the solvent. The thermal decomposition of the metal carboxylate precursor gels was studied by thermogravimetric/differential thermal analyzer （TG/DTA） and the products derived from calcining the gels were characterized by X-ray diffraction （XRD） and transmission electronic microscope （TEM）. The polarization curves were acquired on an electrochemical workstation （LK98） and the discharge curves were acquired on a testing instrument of batteries （DC-5）, with a constant current discharge, less than 120 mA/cm^2. The results revealed that the nanometer perovskite-type powder with lesser particle size could be achieved with an organic solvent and had a better catalytic activity.

Effects of Polar Organic Solvent on Separation of Y(edta)^-/Nd(edta)^- Complexes on Polyacrylic Anion Exchangers

The use of polar organic solvents for the separations of rare earth elements (Ⅲ) is effective especially for their extensive separations despite the solubility limitations. The study shows that polyacrylate anion exchangers, particularly the weakly basic, gel anion exchanger Amberlite IRA 68, can be applied to the separation of rare earth complexes with EDTA in H_2O-methanol and H_2O-ethanol systems. In most cases the determined distribution coefficients of Ln^(3+) complexes with EDTA in mixed media like water-methanol on polyacrylate anion exchangers are larger than those in pure water (media.)

GROWTH OF o-DICYANOVINYL ANISOLE(DIVA) CRYSTAL IN ORGANIC SOLVENTS

Crystal growth habits of O-Dicyanovinyl anisole (DIVA) in organic solvents are described

Stability of M13 Phage in Organic Solvents

The effect of different types of organic solvents on the structural integrity of M13 phages has been directly visualized by transmission and scanning electron microscopy. The exposure of M13 phages to apolar hexane had no effect on the structure of the phages for up to 8 h. In contrast, phages showed ~10-fold contraction into rod-like I-forms and to flattened spheroids with ~12 nm diameter upon exposure to polar organic solvents. We show that this finding can be beneficial for the macromolecular self-assembly and in broader aspects, to enhance the spatial arrangement of desired inorganic nanoparticles in the rapidly developing field of virotronics.

Subacute Chorea Induced by Organic Solvents

Introduction: Chronic exposure to organic solvents may result in a variety of neurologic complications like dementia, cerebellar dysfunction, pyramidal syndrome, cranial nerve abnormalities, and neuropathy. Clinical Presentation: We report an unusual case of subacute chorea induced by occupational exposure. Brain magnetic resonance imaging showed diffuse white matter T2 hyperintensity. The screening of basic blood tests, and CSF studies to eliminate alternate diagnoses, were normal. The patient received 1000 mg/day of intravenous methylprednisolone for 3 days, with cessation of professional activity. We observed a regression of neurological symptoms after 3 months of follow-up. Conclusion: This case highlights the diversity of acute or chronic neurological complications of solvents.

Ultrathin organic solvent nanofiltration membrane with polydopamine-HKUST-1 interlayer for organic solvent separation

Polydopamine(PDA)and metal-organic skeleton HKUST-1 were co-deposited on the base membrane of hexamethylenediamine(HDA)-crosslinked polyetherimide(PEI)ultrafiltration membrane as the interlayer,and high-throughput organic solvent nanofiltration membrane(OSN)was prepared by interfacial polymerization and solvent activation reaction.The polyamide(PA)layer surface roughness from 28.4 nm in PA/PEI to 78.3 nm in PA/PDA-HKUST-10.6/PEI membrane,reduced the thickness of the separation layer from 79 to 14 nm,and significantly improved the hydrophilic,thermal and mechanical properties.The flux of the PA/PDA-HKUST-10.6/PEI membrane in a 0.1 g/L Congo Red(CR)ethanol solution at 0.6 MPa test pressure reached 21.8 L/(m^(2)·hr)and the rejection of CR was 92.8%.Solvent adsorption test,N,N-dimethylformamide(DMF)immersion experiment,and long-term operation test in ethanol showed that the membranes had high solvent tolerance.The solvent flux test demonstrated that,under the test pressure of 0.6 MPa,the flux of different solvents ranked as follows:methanol(56.9 L/(m^(2)·hr))>DMF(39.6 L/(m^(2)·hr))>ethanol(31.2 L/(m^(2)·hr))>IPA(4.5 L/(m^(2)·hr))>N-hexane(1.9 L/(m^(2)·hr)).The ability of the membranes to retain dyes in IPA/water dyes solution was also evaluated.The flux of the membrane was 30.4 L/(m^(2)·hr)and the rejection of CR was 91.6%when the IPA concentration reached 50%.This OSN membrane-making strategy is economical,environment-friendly and efficient,and has a great application prospect in organic solvent separation systems.

Amino acids modified nanoscale zero-valent iron:Density functional theory calculations,experimental synthesis and application in the Fenton-like degradation of organic solvents

To improve the adsorption and catalytic performance of heterogeneous Fenton-like catalysts for oil wastes,amino acids were used to modify nanoscale zero-valent iron(AA@Fe^(0)),which were applied in the Fenton-like degradation of organic solvents(tributyl phosphate and n-dodecane,named TBP and DD).Twelve amino acids,i.e.,glycine(Gly),alanine(Ala),leucine(Leu),proline(Pro),phenylalanine(Phe),methionine(Met),cysteine(Cys),asparagine(Asn),serine(Ser),glutamic acid(Glu),lysine(Lys)and arginine(Arg),were selected and calculated by density functional theory(DFT).The optimized structure,charge distribution,the highest occupied molecular orbital(HOMO),the lowest unoccupied molecular orbital(LUMO),interaction region indicator(IRI)isosurface map and adsorption energy of AA@Fe^(0),AA@Fe^(0)-TBP and AA@Fe^(0)-DD were studied,which indicated that Fe is more likely to approach and charge transfer with-COO and-NH_(3) on theα-carbon of amino acids.There is strong attraction between Fe and–COO,and Van der Waals force between Fe and-NH_(3),respectively.In the interaction of AA@Fe^(0)with TBP and DD,Van der Waal force plays an important role.AA@Fe^(0)was synthesized in laboratory and characterized to investigate physicochemical properties.In Fenton-like degradation of organic solvents,the change of COD in water phase during the degradation process as well as the volume of the organic phase after the reaction were investigated.The results of calculations combined with experiments showed that Ser-modified Fe^(0)performed the best in these amino acids,with 98%removal of organic solvents.A possible catalytic mechanism was proposed in which amino acids acted a linking role between Fe and organic solvents,activating H_(2)O_(2)to generate hydroxyl radicals for the degradation of organic solvents.

Free radical oxidation of spent radioactive organic solvent

The decomposition of radioactive Spent Organic Solvent (SOS) was conducted successfully in bench scale tests. The experiment results showed that TBP/OK can be decomposed under with in H 2O 2 Fe 2+ /TiO 2 H 2SO 4 systems under suitable H 2O 2 concentration, catalyst, temperature and pH. The free radical oxidation reaction mechanism using H 2O 2 under the action of the synergistic catalysis TiO 2/Fe 2+ was also discussed briefly.

Physiological cellular responses and adaptations of Rhodococcus erythropolis IBB_(Po1) to toxic organic solvents

A new Gram-positive bacterium, Rhodococcus erythropolis IBBPo1（KF059972.1） was isolated from a crude oil-contaminated soil sample by enrichment culture method. R. erythropolis IBBPo1 was able to tolerate a wide range of toxic compounds, such as antibiotics（800–1000 μg/mL）,synthetic surfactants（50–200 μg/mL）, and organic solvents（40%–100%）. R. erythropolis IBBPo1 showed good tolerance to both alkanes（cyclohexane, n-hexane, n-decane） and aromatics（toluene, styrene, ethylbenzene） with logPOW（logarithm of the partition coefficient of the solvent in octanol–water mixture） values between 2.64 and 5.98. However, alkanes were less toxic for R. erythropolis IBBPo1 cells, compared with aromatics. The high organic solvent tolerance of R. erythropolis IBBPo1 could be due to the presence in their large genome of some catabolic（alkB, alkB1, todC1, todM, xylM）, transporter（HAE1） and trehalose-6-phosphate synthase（otsA1, KF059973.1） genes. Numerous and complex physiological cellular responses and adaptations involved in organic solvent tolerance were revealed in R. erythropolis IBBPo1 cells exposed 1 and 24 hr to 1% organic solvents. R. erythropolis IBBPo1 cells adapt to 1% organic solvents by changing surface hydrophobicity, morphology and their metabolic fingerprinting.Considerable modifications in otsA1 gene sequence were also observed in cells exposed to organic solvents（except ethylbenzene）.

Photodegradation of new herbicide HW-02 in organic solvents

HW-02 is a new organophosphates herbicide which is discovered and developed in China. The kinetics and mechanism of HW-02 photodegradation in the organic solvents were studied at 25°C under the irradiation of ultraviolet light. The results showed that photochemical reaction of HW-02 in organic solvents such as n-hexane, methanol, dimethyl benzene and acetone under UV light could be well described by the first kinetic equation, and the photodegradation efficiency decreased with a order of n-hexane methanol xylene acetone. The photodegradation efficiency constant of HW-02 in n-hexane, methanol, xylene and acetone were 4.951 × 10^-2 , 3.253 × 10^-2 , 2.377 × 10^-2 and 1.628 × 10^-2 min 1 , and the corresponding half-lives were 13.99, 21.20, 29.15 and 42.56 min, respectively. By separation and identification of photoproducts using GC-MS, it could be concluded that HW-02 was photolyzed through ester cleavage, photo-dechlorination and photoisomerization of the molecule itself.

Bamboo charcoal fused with polyurethane foam for efficiently removing organic solvents from wastewater:experimental and simulation

The development of a multifunctional oil adsorbing material which could effectively and quickly separate oily wastewater is one of the focuses in water environment restoration.In this study,bamboo charcoal(BC)was used as an improver to modify polyurethane(PU)foam.The results of scanning electron microscope(SEM)and Fourier-transform infrared spectroscopy(FTIR)revealed that the addition of BC could effectively improve the mechanical properties of PU.The adsorption data exhibited that the BC-loaded PU(BC/PU)foam composites effectively removed seven organic solvents(OSs,including octane,petroleum ether,soybean oil,chlorobenzene,1,2-dichloroethane,n-hexane,cyclohexane),and the maximum adsorption capacity of BC/PU was 23.6 g g^(−1)when BC content was 5%.The order of pseudo-second-order kinetic constants and maximum adsorption capacity of seven OSs was octane<petroleum ether<soybean oil<chlorobenzene<1,2-dichloroethane<cyclohexane<n-hexane.Based on the experimental data and density functional theory(DFT)simulation,the adsorption mechanism of OSs on BC/PU-5 was discussed.The EHOMO andμof OSs calculated by DFT were highly correlated with absorption affinity(K_(2),Q_(e)and Q_(max)).Hence,the contribution of OSs to the adsorption efficiency of BC/PU-5 may be mainly due to electron donor-acceptor(EDA)interaction and non-hydrophobic interaction.In addition,the adsorption capacity did not change significantly after repeated recycling 5 times.Overall,the prepared BC/PU foam composites could be used as a potential candidate for separating OSs in engineering applications.

Experimental Study on Conditioning of Spent Organic Solvent (TBP/OK)

Spent Organic Solvent (SOS),TBP/OK is one of the low and intermediate level liquid radioactive wastes generated in nuclear facilities. This paper studies the decomposition behavior of SOS in H2O2-Fe2+/TiO2-H2SO4 systems and analyzes the effects of such factors ad H2O2 concentration,catalysts,temperature adn pH on the reaction process. The physical and chemical characteristics of the reaction condensate and decomposition residual from preliminary experimental results are also described. The chemical oxidation reaction mechanism using H2O2 under the action of the synergetic catalysis TiO2/Fe2+ is also discussed briefly.

Theoretical investigations of transport properties of organic solvents in cation-functionalized graphene oxide membranes： Implications for drug delivery

We perform detailed quantum chemical calculations to elucidate the origin and mechanism of the selective permeability of alkali and alkaline earth cation- decorated graphene oxide （M-GO） membranes to organic solvents. The results show that the selectivity is associated mainly with the transport properties of solvents in the membranes, which depends on two regions of the flow path： the sp3 C-O matrix of the GO sheets and the cation at the center of the hexagon rather than the sp~ region. According to the delocalization of ~ states in sp2 regions, we propose a design guide for high-quality M-GO membranes. The solvent-cation interaction essentially causes directional transport of molecules in the M-GO membranes under the transmembrane pressure, indicating a site-to-site mech- anism. The solvent-sp3 C-O matrix interaction may inhibit molecular transport between two fixed cations by consuming energy. The competition between energy consumption by the solvent-cation interaction and energy expenditure by the solvent-sp3 C-O matrix interaction leads to various transport properties of solvents and thus allows for the selective permeability of the M-GO membranes. Findings from the study are helpful for the future design of multifunctional M-GO macro-membranes as cost-effective solution nanofilters in chemical, biological, and medical applications

π-Extension and chlorination of non-fullerene acceptors enable more readily processable and sustainable high-performance organic solar cells

Organic solar cells(OSCs)processed without halogenated solvents and complex treatments are essential for future commercialization.Herein,we report three novel small molecule acceptors(NFAs)consisting of a Y6-like core but withπ-extended naphthalene with progressively more chlorinated end-capping groups and a longer branched chain on the Nitrogen atom.These NFAs exhibit good solubilities in nonchlorinated organic solvents,broad optical absorptions,closeπ-πstacking distances(3.63–3.84A),and high electron mobilities(~10^(-3)cm^(2)V^(-1)s^(-1)).The o-xylene processed and as-cast binary devices using PM6 as the donor polymer exhibit a PCE increasing upon progressive chlorination of the naphthalene end-capping group from 8.93%for YN to 14.38%for YN-Cl to 15.00%for YN-2Cl.Furthermore similarly processed ternary OSCs were fabricated by employing YN-Cl and YN-2Cl as the third component of PM6:CH1007 blends(PCE=15.75%).Compared to all binary devices,the ternary PM6:CH1007:YN-Cl(1:1:0.2)and PM6:CH1007:YN-2Cl(1:1:0.2)cells exhibit significantly improved PCEs of 16.49%and15.88%,respectively,which are among the highest values reported to date for non-halogenated solvent processed OSCs without using any additives and blend post-deposition treatments.

Assessment of Nanoparticle-Enriched Solvents for Oil Recovery Enhancement

Solvents are generally used to reduce the viscosity of heavy crude oil and ultimately enhance oil recovery.Recently,a new method has been introduced where nanoparticles(NPs)are exploited to induce enhanced oil recovery owing to their ability to improve the mobility ratio,dampen the interfacial tension,and alter rock wett-ability.This study investigated the integration of nano-alumina(Al_(2)O_(3))NPs with an n-hexane solvent.In parti-cular,a Brookfield viscometer has been used to measure the crude oil viscosity and it has been found that NPs can effectively lead to a significant decrease in the overall oil viscosity(70 cp using the solvent only,45 cp when NPs are added).

Distribution and sources of solvent extractable organic compounds in PM_(2.5) during 2007 Chinese Spring Festival in Beijing

The solvent extractable organic compounds （SEOC）, including n-alkanes, polycylic aromatic hydrocarbons, fatty acids, and dicarboxylic acids in PM2.5 during the 2007 Chinese Spring Festival in Beijing, were measured via gas chromatography-mass spectrometry for determining the characteristics and sources of these organic pollutants. The concentrations of total n-alkanes, PAHs, and organic acids before Chinese Spring Festival Eve （1025.5, 95.9, and 543.3 ng/m3, respectively） were higher than those after （536.6, 58.9, and 331.8 ng/m3, respectively）, n-Aalkanes and PAHs had much higher concentration in nighttime than those in daytime because of high relative humidity and low wind speed during the night. Combustion of coal and exhaust emission were major sources of n- alkanes. It could be concluded by the characteristic ratios that the primary source of PAHs in fine particles was the combustion of coal, but the combustion of gasoline was in the next place. The ratios of C18：0/C16 indicated the contribution of vehicular emissions to the fatty acids. Dicarboxylic and aromatic acids were abundant in daytime than in nighttime because these acids were secondary organic acid and the photochemical degradation of aromatic hydrocarbons was the main source.