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Photocatalytic CO2 reduction is a sustainable and inexpensive method to solve the energy crisis and the greenhouse effect. However, the major stumbling blocks such as poor product selectivity, low yield of the multi-carbon products, and serious recombination of electron-hole pairs hinder practical application of photocatalysts. Herein, a high-performance Bi@Bi2 MoO6 photocatalyst, Bi nanoparticles grown on the surface of Bi2 MoO6 nanosheets with oxygen vacancies, was fabricated via a simple solvothermal approach. Benefiting from the abundant active sites and effective separation of photogenerated carriers of Bi2 MoO6 nanosheets, and the localized surface plasmon resonance effect of Bi nanoparticles, the Bi@Bi2 MoO6 sample exhibited great photocatalytic CO2 reduction activity. Furthermore, adding NaHCO3 into the system not only significantly increased the C2 H5 OH generation rate but also enhanced the product selectivity. In the photocatalytic measurement (0.17 mol L-1 CO2 -saturated NaHCO3 solution), the highest formation rates of CO, CH3 OH, and C2 H5 OH were reached at 0.85, 0.59, and 17.93 μmol g-1 h-1 (≈92 % selectivity), respectively.

Summary Design of polymeric networks with unique structural motifs can permit dynamic features, yet most existing material systems exhibit limited operational states or irreversible responsiveness. Here, we use a hydrogen-bond topological network as the design principle to construct an ionic gel material based on cellulose, ionic liquid, and H2O (designated as Cel-IL dynamic gel). The prepared Cel-IL dynamic gels exhibit tunable properties of mechanical strength, ionic conductivity, viscoelasticity, and self-healing. With limited H2O, the Cel-IL dynamic gel exhibits a bramble-like Turing-pattern microstructure with excellent adhesion, rapid self-healing, and moderate ionic conductivity features. By increasing the H2O content to 32 wt %, the microstructure switched to a dense and compact Turing pattern network, giving the gel good stretchability, robust toughness, and a high ionic conductivity. With this material, we demonstrate a flexible, transparent, designable, and biocompatible ion sensor device, which exhibits great potential for use in electronic skins and intelligent devices.

The separator is of great importance for regulating ion transmission, maintaining electrode stability, and device safety in lithium‐ion batteries. Despite their many advantages, glass microfiber separators have shortcomings that often give rise to poor cycle performance and fatal short‐circuit risk when used in flexible batteries. Here, we propose the use of a scalable non‐Newtonian fluidic cellulose permeation‐diffusion strategy to develop a cellulose/glass microfiber composite film with an hourglass‐gradient structure. Due to the unique gradient morphology resulting from the presence of cellulose macromolecules, the as‐prepared composite film showed an improved surface mass density, adjustable pore structure, controllable ion transport, ideal mechanical flexibility, and robustness. When used as the separator in an assembled lithium‐ion battery, the composite film exhibited rapid ion diffusion and Li dendrite inhibition, which endowed the battery with excellent cycle stability (specific capacity of 108.5 mAh g−1 after 1000 cycles) and good rate performance. This composite film shows great potential application in flexible lithium‐ion batteries including but not limited to pouch cells.

Fabricating a high-performance photocatalyst to efficiently solve serious environmental problems is an urgent affair. Herein, a series of MoS2 /ZnO composites were successfully fabricated through a facile hydrothermal route using Na2 MoO4 , (NH2 )2 CS and urchin-like ZnO as precursors. According to the results of XRD and XPS, it was found that ZnS appeared in MoS2 /ZnO composite; meanwhile, the content was positively correlated with the weight of the precursor (NH2 )2 CS. It should be noted that the morphology and the metallic phase content of MoS2 grown in situ on the surface of ZnO were affected by the molar ratio of Na2 MoO4 and ZnO. Benefiting from the special dual II heterojunctions of MoS2 /ZnS/ZnO ternary composite, the material exhibited excellent charge separation and transfer performances. In the photocatalytic measurements, the MoS2 /ZnS/ZnO (Na2 MoO4 :ZnO 1:2 MZ2) composite not only exhibits excellent photocatalytic CrVI reduction activity of 42.3×10-3 min-1 , but also displays remarkable adsorption performance (nearly 32.1 %) for Cr2 O 2 - 7 . In addition, the ternary composite shows dominant photocatalytic CrVI reduction activities compared to other photocatalysts. This work provides a high-efficient MoS2 /ZnS/ZnO ternary photocatalyst for environmental treatment.

Herein, silver (Ag)-based urchin-like E-graphite carbon nitride/titanium dioxide (E-g-C3N4/TiO2) ternary composite was successfully synthesised via hydrothermal process and it showed excellent photocatalytic activity. The large interfacial contact between three-dimensional (3D) urchin-like TiO2 (UT) and g-C3N4 leads to high photocatalytic activity, compared with pure 3D UT. To enlarge the response of light and enhance the charge carriers’ transfer, the Ag nanoparticles with average sizes of 13 nm were loaded on the surface of g-C3N4/TiO2. Photodegradation test results of RhB shown that the 3% Ag-based urchin-like E-g-C3N4/TiO2 composite has the highest catalytic activity, which reaches 97.98%. Thus, the material has a promising application for the degradation of organics.

Structure heterogeneity and host nucleic acids contamination are two major problems for virus-like particles (VLPs) produced by various host cells. In this study, an in vitro optimized disassembly-purification-reassembly process was developed to obtain uniform and nucleic acid free hepatitis B core (HBc) based VLPs from E. coli fermentation. The process started with ammonium sulfate precipitation of all heterogeneous HBc structures after cell disintegration. Then, dissolution and disassembly of pellets into basic subunits were carried out under the optimized disassembly condition. All contaminants, including host nucleic acids and proteins, were efficiently removed with affinity chromatography. The purified subunits reassembled into VLPs by final removal of the chaotropic agent. Two uniform and nucleic acid free HBc-based VLPs, truncated HBc149 and chimeric HBc183-MAGE3 I, were successfully prepared. It was found that disassembly degree of HBc-based VLPs had a great influence on the protein yield, nucleic acid removal and reassembly efficiency. 4 M urea was optimal because lower concentration would not disassemble the particles completely while higher concentration would further denature the subunits into disordered aggregate and could not be purified and reassembled efficiently. For removal of strong binding nucleic acids such as in the case of HBc183-MAGE3 I, benzonase nuclease was added to the disassembly buffer before affinity purification. Through the optimized downstream process, uniform and nucleic acid free HBc149 VLPs and HBc183-MAGE3 I VLPs were obtained with purities above 90% and yields of 55.2 and 43.0 mg/L, respectively. This study would be a reference for efficient preparation of other VLPs.

There is currently enormous and growing demand for flexible electronics for personalized mobile equipment, human-machine interface units, wearable medical-healthcare systems, and bionic intelligent robots. Cellulose is a well-known natural biopolymer that has multiple advantages including low cost, renewability, easy processability, and biodegradability, as well as appealing mechanical performance, dielectricity, piezoelectricity, and convertibility. Because of its multiple merits, cellulose is frequently used as a substrate, binder, dielectric layer, gel electrolyte, and derived carbon material for flexible electronic devices. Leveraging the advantages of cellulose to design advanced functional materials will have a significant impact on portable intelligent electronics. Herein, the unique molecular structure and nanostructures (nanocrystals, nanofibers, nanosheets, etc.) of cellulose are briefly introduced, the structure-property-application relationships of cellulosic materials summarized, and the processing technologies for fabricating cellulose-based flexible electronics considered. The focus then turns to the recent advances of cellulose-based functional materials toward emerging intelligent electronic devices including flexible sensors, optoelectronic devices, field-effect transistors, nanogenerators, electrochemical energy storage devices, biomimetic electronic skins, and biological detection devices. Finally, an outlook of the potential challenges and future prospects for developing cellulose-based wearable devices and bioelectronic systems is presented.

A temperature controlled low field nuclear magnetic resonance (LF-NMR) T2 relaxometry technique based on the mobility changes of water trapped in hydrogels, was successfully used for on-line determination of the sol-gel transition temperature for chitosan/β-glycerophosphate (CS/GP) hydrogels in real time. The LF-NMR results indicated that the gelation temperature decreased gradually with increasing GP concentration, and the results were supported by both thermogravimetric differential scanning calorimetry (DSC) and rheological findings; however, LF-NMR allows non-destructive monitoring of samples during continuous heating. Moreover, as the mobility of water molecules varies greatly during the sol-gel phase transition, the LF-NMR measurement was more sensitive and accurate (RSD ≤ 0.1 %, n = 5) compared with DSC (RSD: 1.2 %–3.7 %, n = 5) and rheology (RSD: 1.1 %–2.3 %, n = 5).

Summary: Zika virus (ZIKV) infection causes Guillain-Barré syndrome and severe birth defects. ZIKV envelope (E) protein is the major viral protein involved in cell receptor binding and entry and is therefore considered one of the major determinants in ZIKV pathogenesis. Here we report a gene-wide mapping of functional residues of ZIKV E protein using a mutant library, with changes covering every nucleotide position. By comparing the replication fitness of every viral mutant between mosquito and human cells, we identified that mutations affecting glycosylation display the most divergence. By characterizing individual mutants, we show that ablation of glycosylation selectively benefits ZIKV infection of mosquito cells by enhancing cell entry, whereas it either has little impact on ZIKV infection on certain human cells or leads to decreased infection through the entry factor DC-SIGN. In conclusion, we define the roles of individual residues of ZIKV envelope protein, which contribute to ZIKV replication fitness in human and mosquito cells. : Entomology; Genomics; Virology; Protein Structure Aspects Subject Areas: Entomology, Genomics, Virology, Protein Structure Aspects

To improve the ability of water to wet coal in the process of coal seam water injection, different ionic liquids and surfactant compound solutions were added to water. Analyses of surface tension, reverse spontaneous imbibition, and contact angle were used to optimize the different compound solutions. The results showed that when the mixture ratio of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) and sodium dodecyl sulfate (SDS) was 3:1, and the concentration of the composite solution reached 0.1 wt%, the liquid surface tension reached a minimum of 28.946 mN/m, and the contact angle between the solution and the coal sample was 41.3°, which was lower than that of any concentrations of the other composite solutions. This solution could effectively wet the coal. In addition, infrared spectroscopy showed that different concentrations of the [BMIm][BF4] and SDS composite solution had different effects on the content of functional groups in coal. Further, based on the relationship between the content of the functional groups and contact angle, the relationship between the content of ring hydroxyl and OH⋯O in the hydroxyl structure and the size of the contact angle was found to be the most significant. Based on the above findings, a new type of composite wetting agent was prepared, and the wetting mechanism between coal and the wetting agent was clarified from the perspective of functional groups. The research results have important guidance and practical significance for improving the effect of increasing moisture and reducing dust in the process of coal seam water injection.

Human ferritin (HFn) nanocaging is becoming an appealing platform for anticancer drugs delivery. However, protein aggregation always occurs during the encapsulation process, resulting in low production efficiency. A new approach using high hydrostatic pressure (HHP) was explored in this study to overcome the problem of loading doxorubicin (DOX) in HFn. At the pressure of 500MPa and pH 5.5, DOX molecules were found to be encapsulated into HFn. Meanwhile, combining it with an additive of 20mM arginine completely inhibited precipitation and aggregation, resulting in highly monodispersed nanoparticles with almost 100% protein recovery. Furthermore, stepwise decompression and incubation of the complex in atmospheric pressure at pH 7.4 for another period could further increase the DOX encapsulation ratio. The HFn-DOX nanoparticles (NPs) showed similar morphology and structural features to the hollow cage and no notable drug leakage occurred for HFn-DOX NPs when stored at 4°C and pH 7.4 for two weeks. HFn-DOX NPs prepared through HHP also showed significant cytotoxicity in vitro and higher antitumor bioactivity in vivo than naked DOX. Moreover, This HHP encapsulation strategy could economize on DOX that was greatly wasted during the conventional preparation process simply through a desalting column. These results indicated that HHP could offer a feasible approach with high efficiency for the production of HFn-DOX NPs.

Recent improvements in flexible electronics have increased the need to develop flexible and lightweight power sources. However, current flexible electrodes are limited by low capacitance, poor mechanical properties, and lack of cycling stability. In this article, we describe an ionic liquid-processed supramolecular assembly of cellulose and 3,4-ethylenedioxythiophene for the formation of a flexible and conductive cellulose/poly(3,4-ethylenedioxythiophene) PEDOT:poly(styrene sulfonate) (PSS) composite matrix. On this base, multiwalled carbon nanotubes (MWCNTs) were incorporated into the matrix to fabricate an MWCNT-reinforced cellulose/PEDOT:PSS film (MCPP), which exhibited favorable flexibility and conductivity. The MCPP-based electrode displayed comprehensively excellent electrochemical properties, such as a low resistance of 0.45 Ω, a high specific capacitance of 485 F g–1 at 1 A g–1, and good cycling stability, with a capacity retention of 95% after 2000 cycles at 2 A g–1. An MCPP-based symmetric solid...

Camptothecin (CPT) is considered one of the most important antitumor agents in the treatment of colon cancer. We synthesized a series of novel CPT (irinotecan, CPT-11) derivatives, which have impressive effects in various tumors. This study investigated the antitumor mechanism of one representative compound, ZBH-01 in colon cancer both in vitro and in vivo. The antiproliferative effect of ZBH-01 on tumor cells was evaluated by MTT assay. Topoisomerase I (Topo I) function and expression were assessed using DNA relaxation assay,qRT-PCR and western blot. Different gene expression among ZBH-01, CPT-11, and SN38 group was analyzed by RNA-seq and verified using qRT-PCR. GO and KEGG pathway analysis of DEmRNAs was performed by “R”. Protein-protein interaction (PPI) networks were constructed by STRING. The screened out mRNAs were functionally annotated. Cell cycle progression and cell apoptosis were assessed by flow cytometry. ZBH-01's inhibition of tumor growth was assessed using xenografts models established from SW1116 cells and colon cancer tissue samples. The results showed that ZBH-01 has comparable or superior antitumor activity against multiple tumor cell lines as compare with CPT-11 and SN38 (7-Ethyl-10-hydroxy camptothecin). It reduced colon tumor growth superior to CPT-11 in vivo with lower toxicity. ZBH-01 showed a similar mechanism but weaker inhibitory activity on Topo I compared to CPT-11 or SN38. The screening criteria for DEmRNAs are P-value < 0.05 and |log2 fold change | > 1. A total of 100 DEmRNAs (62 downregulated and 38 upregulated mRNAs) have the same expression pattern in the three drug groups. Notably, there are 1769 DEmRNAs (842 downregulated and 927 upregulated mRNAs) specifically expressed in ZBH-01 group as compare with CPT-11 and SN38 group. GO analysis stratified these DEmRNAs in BP (sister chromatid segregation, DNA-dependent DNA replication), MF (catalytic activity, acting on DNA), CC (chromosomal region, condensed chromosome) classifications. The most significantly enriched KEGG pathways for the DEmRNAs in ZBH-01 group were DNA replication, P53 signaling pathway, and cell cycle etc. PPI network construction identified a significant cluster containing 73 genes, which include 14 genes involved in cell cycle process that were verified by qRT-PCR. More precisely, 50 nmol/L ZBH-01 significantly induced cell cycle arrest and apoptosis of colon cancer cells with the changes in gene expression such as p53, CDK2, CCNA2, Bax, Bcl-2, caspase 3, PARP. The further significant result is that ZBH-01 can rapidly exert cytotoxicity after 4 hours of dosing. In contrast, CPT-11 and SN38 had no detectable effect on tumor cells at this time point. In conclusions, ZBH-01 has higher potency in inhibiting colon tumor growth than CPT-11 and SN38 both in vitro and in vivo. It rapidly induces tumor cell apoptosis and cell cycle arrest through regulation of cell cycle signaling pathway. The more precise mechanism of ZBH-01 need to be further studied. Citation Format: Yongqi Li, Zhengkun Tu, Dawei Zhao, Wenqiu Zhang, Miaomiao Yang, Zhihui Wu, Weiguo Shi, Shijie lan, Zhen Guo, Hong Yu, Di Wu. Antitumor activity of a novel irinotecan analog, ZBH-01 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1835.

Improving the conductivity stability of flexible conductors has a positive impact on the working performance and service life of portable electronic devices. However, designing a conductor material with both conductivity-stable and flexible performance is still not an easy task because of the conductive network damage under large deformation or high humidity conditions. Here, we surmount this challenge by developing an interfacial assembly/encapsulation integration strategy for the construction of flexible, transparent, and conductivity-stable film. Under the synergistic effect of coordination complexation and hydrogen bonding, silver nanowires (AgNWs) are sandwiched encapsulated by regenerated cellulose film (as flexible substrate) and poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) nanosheets (as sealing coat). The resulting hybrid film has a robust interfacial structure and prominently stable properties. Even when subjected to harsh condition such as a high-moisture environment of 90% relative humidity and 65 °C temperature for up to 60 days, repeated bending for 500 times, peeling over 400 times or soaking in water for 30 days, the film still exhibits a high and stable conductivity, better than most previously reported values for AgNWs-based films. With this strategy as base, we demonstrate a flexible, transparent and biocompatible strain-to-electricity sensor with high working stability and performance.

Camptothecin (CPT) is a cytotoxic quinoline alkaloid that is used clinically as an anticancer drug. However, the clinical application of CPT is limited due to its low solubility as well as serious and unfathomable side-effects. In the present study, we created a novel 10-hydroxy CPT prodrug, ZBH-ZM‑06. Its cellular cytotoxic activity was analyzed in terms of cellular viability, acetylcholinesterase (AchE) inhibition, DNA relaxation, cellular cycling and apoptosis properties. Our results showed that the AchE inhibition rate of 10 µmol/l ZBH-ZM-06 was 12.5%, compared to 96.5% for carbonyl-oxycamptothecin (CPT-11). In a chemical stability assay, only 4.9% of ZBH-ZM-06 remained after 4 h at pH 7.4. In addition, 10 µmol/l ZBH-ZM-06 significantly inhibited the tumor cell viability of nine tumor cell lines, compared to CPT-11 and the CPT active ingredient, 7-ethyl-10-hydroxy-camptothecin (SN38) (p

Zika virus (ZIKV) infection causes Guillain-Barré syndrome and severe birth defects. ZIKV envelope (E) protein is the major viral protein involved in cell receptor binding and entry and therefore considered one of the major determinants in ZIKV pathogenesis. Here, we report a gene-wide mapping of functional residues of ZIKV E protein using a mutant library with changes covering every nucleotide position. By comparing the replication fitness of every viral mutant between mosquito and human cells, we identified that mutations affecting N-linked glycosylation at N154 position display the most divergence. Through characterizing individual mutants, we show that, while ablation of N-linked glycosylation selectively benefits ZIKV infection of mosquito cells by enhancing cell entry, it either had little impact on ZIKV infection on certain human cells or decreased infection through entry factor DC-SIGN. In conclusion, we define the roles of individual residues of ZIKV envelope protein, which contribute to ZIKV replication fitness in human and mosquito cells.HighlightsGene-wide mapping of functional residues of E protein in human and mosquito cells.Mutations affecting N-linked glycosylation display the most dramatic difference.N-linked glycosylation decreases ZIKV entry into mosquito cells.N-linked glycosylation is important for DC-SIGN mediated infection of human cells.

A porous structure is the key factor to successful chromatography separation. Agarose gel as one of the most popular porous media has been extensively used in chromatography separation. As the cooling process in the agarose gelation procedure can directly influence the pore structure, ten kinds of 4% agarose media with different cooling rates from 0.132 to 16.7°C/min were synthesized, and the pore structure was determined accurately by using low-field NMR spectroscopy. The curves of pore structure and cooling rate can be divided into two stages with the boundary of 6°C/min. In stage I, the pore structure met a power equation with the decrease of the cooling rate, and in stage II, the process reached a plateau. Confirmatory experiments proved that, by adjusting the cooling rate, a precise control of the pore structure of agarose media can be realized, furthermore, cooling rate optimization was an effective way to control the pore size of agarose media and can further tailor the pore structure for more effective separation of different proteins.

Objective This study was performed to identify the correlation between contrast-enhanced ultrasound (CEUS) and contrast-enhanced multidetector computed tomography (CE-MDCT) as well as the correlation between serum liver enzyme concentrations and CE-MDCT in classification of the severity of blunt hepatic trauma using CE-MDCT as a reference standard. Materials and methods A blunt liver trauma model was created using 20 rabbits, and CE-MDCT, CEUS, and serum liver enzyme assays were performed. A radiologist and an ultrasound physician independently evaluated the degree of liver trauma. The diagnostic performance of CEUS and serum liver enzyme measurements was compared with that of CE-MDCT using Spearman’s correlation analysis and Pearson’s correlation analysis, respectively. Results Spearman’s rank correlation coefficient between the CEUS-based classification and CE-MDCT was 0.888. The aspartate aminotransferase and lactate dehydrogenase concentrations and the aspartate aminotransferase/alanine aminotransferase ratio were positively correlated with the grade of liver injury; Pearson’s correlation coefficients were 0.664, 0.704, and 0.503, respectively. The gamma-glutamyltransferase concentration had a significantly negative correlation with the grade of liver injury (r = −0.467). Conclusions CEUS and serum liver enzyme measurement exhibited high consistency with CE-MDCT for both detection and grading of intraparenchymal lesions in blunt liver trauma. These techniques may permit more accurate diagnosis of liver trauma.

Sol–gel transition properties play a key role in various applications of thermosensitive hydrogels, but conventional methods for studying the sol–gel transition have some limitations. For extensive characterization of the water–polymer interaction and microstructure change during sol–gel transition, we propose a rapid and nondestructive method based on monitoring water mobility through low field NMR (LF-NMR), and this was applied to chitosan/β-glycerophosphate (CS/GP) hydrogels. The spin–spin relaxation time (T2) that depicted water mobility was measured by LF-NMR within 90 s. The T2 component corresponding to water protons trapped in polymer networks (T21) was very sensitive to sol–gel transition. A remarkable decrease of T21 value indicated obvious variations of water mobility when CS/GP was heated, and a turning point was observed on the T21–time curve. The gel point associated with this turning point could be easily determined by fitting the T21–time curves to a bilinear regression model, and the results showed good accuracy and repeatability owing to the nondestructive nature of LF-NMR. Variations in water components and microstructure of CS/GP caused by water migration after solidification were also analyzed by monitoring dynamic changes of T2. This rapid, nondestructive method provides a powerful tool for studying the sol–gel transition of hydrogels.

The porous structure characteristics of twenty-one porous microspheres with agarose framework were investigated based on the low-field nuclear magnetic resonance (LF NMR) relaxation time (T 2) distribution measurements. The feasibility of the technique was confirmed by direct relationship between T 2 and the mean pore size of the polymer networks (Rh) of agarose hydrogel which was established using the “Fiber-Cell” model. The expected pore radius distribution curve was obtained and the reliability was validated by comparing them with the results obtained by inverse size-exclusion chromatography. Thereafter, the technique was applied to characterize the pore size distribution (PSD) of soft microspheres and the pore size transformation of microspheres with or without grafted polymers in the process of protein adsorption. All of these results strongly support LF NMR as a promising, rapid and nondestructive technique for the determination of PSDs in many kinds of soft porous microspheres.

In this study, low-cost konjac glucomannan (KGM) microspheres used for desalting were developed by an inverse dispersion method. High concentration of KGM was pretreated to reduce viscosity by acid hydrolysis method under the condition of high temperature and pressure. The selectivity of the obtained cross-linked KGM gels with different degree of crosslinking was studied by constructing calibration curves (K(av)) of standard molecular weight substances. The stability of the gels was investigated, which showed that the KGM microspheres are tolerant to a wide range of pH and stable in all commonly used aqueous buffers, and insensitive to autoclaving as well. Furthermore, protein-desalting performances of GM-1250, a cross-linked KGM microsphere, were evaluated with two proteins, bovine serum albumin and filamentous hemagglutinin, which turned out that GM-1250 is comparable to the widely used commercial product--Sephadex G25 Fine. From economic considerations, KGM gel is a prospective alternative for dextran gels in protein desalting process.

Dynamic characteristics of discharge particles are described within the framework of a two-dimensional photoionization-hydrodynamic numerical model for the discharge process of SF6-N2-CO2 gas mixtures at atmospheric pressure, under a uniform DC applied field. The finite difference—flux corrected transport (FD-FCT) algorithm is used in the numerical implementation for improving the accuracy and efficiency. Then the tempo-spatial distributions of the gap—space electric field and electron velocity are calculated from the microscopic mechanism, and the dynamic behaviors of charged particles are obtained in detail. Meanwhile, the tempo—spatial critical point of the avalanche-to-streamer in this model is discovered, and several microscopic parameters are also investigated. The results showed that the entire gap discharge process can be divided into two phases of avalanche and streamer according to Raether-Meek criterion; the electron density within the discharge channel is lower compared to that of positive and negative ions; space charge effect is a dominant factor for the distortion of spatial electric field, making the discharge channel expand toward both electrodes faster; photoionization provides seed electrons for a secondary electron avalanche, promoting the formation and development speed of the streamer.

Membrane technology is important to the development of modern biotechnology. It has the potential to efficiently refold protein at high concentration that is still a challenge for pharmaceutical protein produced from inclusion bodies. This paper dealt with the application of a polysulfone hollow fiber membrane to protein refolding using recombinant human granulocyte colony-stimulating factor (rhG-CSF) as a model protein. Compared with dilution refolding at protein concentration of 1.0 mg/mL, the crossflow membrane system led to a 16% increase in soluble protein recovery, and a 3.3-fold increase in specific bioactivity. Addition of PEG 6 K at 2 g/L could further improve the soluble protein recovery up to 57%, the specific bioactivity up to 2.2 x 10(8) IU/mL. Addition of dextran at 5 g/L could increase the soluble protein recovery up to 63.6%, the specific bioactivity up to 2.30 x 10(8) IU/mL. By gently and gradually removing denaturant, ultrafiltration membrane system was demonstrated to be very helpful for protein refolding at high concentration. Combining with hydrophilic macromolecular of PEG or dextran could further increase its efficiency. PEG was able to promote the refolding intermediate of rhG-CSF to transfer into the native structure; whereas dextran could enhance protein refolding mainly by weakening shear stress-induced protein aggregation. (C) 2014 Elsevier Ltd. All rights reserved.

As a potential hemoglobin (Hb)-based oxygen carrier (HBOC), the PEGylated Hb has received much attention for its non-nephrotoxicity. However, PEGylation can adversely alter the structural and functional properties of Hb. The site of PEGylation is an important factor to determine the structure and function of the PEGylated Hb. Thus, protection of some sensitive residues of Hb from PEGylation is of great significance to develop the PEGylated Hb as HBOC. Here, Cys-93(β) of Hb was conjugated with 20 kDa polyethylene glycol (PEG20K) through hydrazone and disulfide bonds. Then, the conjugate was modified with PEG5K succinimidyl carbonate (PEG5K-SC) using acylation chemistry, followed by removal of PEG20K Hb with hydrazone hydrolysis and disulfide reduction. Reversible conjugation of PEG20K at Cys-93(β) can protect Lys-95(β), Val-1(α) and Lys-16(α) of Hb from PEGylation with PEG5K-SC. The autoxidation rate, oxygen affinity, structural perturbation and tetramer instability of the PEGylated Hb were significantly decreased upon protection with PEG20K. The present study is expected to improve the efficacy of the PEGylated Hb as an oxygen therapeutic.

Fusing affinity tag at N-terminus was reported to decrease the biological activity of the recombinant human tumor necrosis factor alpha. Although preparation of tag-free rhTNF-alpha has already been achieved, the processes were yet laborious, especially in large scale. In this paper, tag-free rhTNF-alpha was almost equally synthesized by Escherichia coli in both soluble and insoluble forms. A two-step ion exchange chromatography, DEAE-Sepharose combined with CM-Sepharose, was developed to purify the soluble specie from supernatant after cell lysis. Native PAGE and HP-SEC showed the rhTNF-alpha extracted from supernatant existed in a homogeneous form. HP-SAX and SDS-PAGE analysis demonstrated the purity of the final fraction was over 98% with a very high recovery of 75%. Circular dichroism spectrum demonstrated that beta-sheet structure was dominant and fluorescence analysis suggested no dramatic exposure of aromatic amino acid residues on the protein surface. Bioassay indicated that purified rhTNF-alpha was biologically active with a specific activity of approximately 2.0 x 10(7) U/mg. All these results suggested that this two-step ion exchange chromatography is efficient for preparation of biologically active tag-free rhTNF-alpha from supernatant. (C) 2014 Elsevier Inc. All rights reserved.

A new method for studying swelling behavior of hydrogels was developed based on low field NMR (LF-NMR). This method is established on these facts: firstly, internal water (water trapped in hydrogel) and external water (water outside of hydrogel) correspond to different components of transverse relaxation time (T2); secondly, T2 component amplitude is proportional to relative water content; and finally, T2 value is closely related to mesh size of hydrogel network, the main effect being due to the overall concentration (degree of swelling). This method was successfully applied to swelling ratio determination of chitosan/glutaraldehyde (CS/GA) hydrogels in situ, and the results had better accuracy and repeatability compared with that of weighing method. Furthermore, swelling kinetics at different pH and microstructure of CS/GA hydrogels was well elucidated based on T2. It is clearly showed that LF-NMR provides a powerful tool for probing processes related to water transport and microstructure variation of hydrogels.

Air and precipitation measurements at five sites were undertaken from 2001 to 2003 in four different provinces in China, as part of the acid rain monitoring program IMPACTS. The sites were located in Tie Shan Ping (TSP) in Chongqing, Cai Jia Tang (CJT) in Hunan, Lei Gong Shan (LGS) and Liu Chong Guan (LCG) in Guizhou and Li Xi He (LXH) in Guangdong. The site characteristics are quite varied with TSP and LCG located relatively near big cites while the three others are situated in more regionally representative areas. The distances to urban centres are reflected in the air pollution concentrations, with annual average concentrations of SO2 ranging from 0.5 to above 40 μg S m−3. The main components in the airborne particles are (NH4)2SO4 and CaSO4. Reduced nitrogen has a considerably higher concentration level than oxidised nitrogen, reflecting the high ammonia emissions from agriculture. The gas/particle ratio for the nitrogen compounds is about 1:1 at all the three intensive measurement sites, while for sulphur it varies from 2.5 to 0.5 depending on the distance to the emission sources. As in air, the predominant ions in precipitation are sulphate, calcium and ammonium. The volume weighted annual concentration of sulphate ranges from about 70 μeq l−1 at the most rural site (LGS) to about 200 μeq l−1 at TSP and LCG. The calcium concentration ranges from 25 to 250 μeq l−1, while the total nitrogen concentration is between 30 and 150 μeq l−1; ammonium is generally twice as high as nitrate. China's acid rain research has traditionally been focused on urban sites, but these measurements show a significant influence of long range transported air pollutants to rural areas in China. The concentration levels are significantly higher than seen in most other parts of the world.

The mechanism controlling Al solubility in Chinese acidic forest soils is not clearly understood. This is the main limitation to the ability to generate adequate dose-response prediction models of the ecological effect of acid rain. To evaluate the relative significance of possible processes, soils and soil solutions from five forest catchments, located in southern and southwestern China, were collected and analyzed for chemical parameters. Monitoring showed that inorganic Al (Al-i) was the dominant fraction in most soil solutions; organic Al (Al-o) was usually less than 10% of total monomeric Al (Al-a). Aluminum fractions varied significantly between and within the different sites, though appearing to follow a similar pattern. Over the entire pH range of 3.6-5.6, the pAl (i.e. -log of the Al3+ activity) closely correlated with solution pH, following regression slopes of 1.28 and 2.00 for upper and lower soil horizons, respectively. The variations in Al3+ activity could not be explained satisfactorily using mineral dissolution equilibria. Partial least square (PLS) regression showed that soil acidity (quality) and ionic strength (intensity) of the solution were the main explanatory variables for the variation in the concentration of All fractions. Aluminum in upper horizons originated from both organic and inorganic solid Al pools, while aqueous Al in lower horizons was dominantly of inorganic origin. Aluminum solubility was strongly influenced by cation exchange, especially in the upper horizon. In the upper horizon, ionic strength (I) had a greater influence on Al solubility due to cation exchange reaction. In the lower horizon, dissolution of inorganic Al pools by the elevated H+ concentrations was the main Al release mechanism. So Al activity was more dependent on H+ (or pH) in the lower horizon. (c) 2006 Elsevier Ltd. All rights reserved.

Dry deposition in China has not yet been intensively studied even though it constitutes an important pathway for acid deposition. The total deposition was monitored at Tieshanping catchment, a regional remote site in Chongqing City. The dry deposition loads of sulphur, calcium and nitrogen are estimated by using a canopy throughfall approach. The results indicate that the annual dry deposition loads of sulphur and calcium at Tieshanping site are much higher than those measured in forestry areas in other countries, while the dry deposition flux of nitrogen is at a comparable level. The dry deposition loads of sulphur, calcium and nitrogen are all higher than the wet deposition loads. Applying a canopy budget model has proven that the routine, simplified canopy throughfall approach may underestimate the dry deposition flux of nitrogen-containing species.

A flexible, transparent, and renewable mesoporous cellulose membrane (mCel-membrane) featuring uniform mesopores of ≈24.7 nm and high porosity of 71.78% is prepared via a facile and scalable solution-phase inversion process. KOH-saturated mCel-membrane as a polymer electrolyte demonstrates a high electrolyte retention of 451.2 wt%, a high ionic conductivity of 0.325 S cm−1, and excellent mechanical flexibility and robustness. A solid-state electric double layer capacitor (EDLC) using activated carbon as electrodes, the KOH-saturated mCel-membrane as a polymer electrolyte exhibits a high capacitance of 110 F g−1 at 1.0 A g−1, and long cycling life of 10 000 cycles with 84.7% capacitance retention. Moreover, a highly integrated planar-type micro-supercapacitor (MSC) can be facilely fabricated by directly depositing the electrode materials on the mCel-membrane-based polymer electrolyte without using complicated devices. The resulting MSC exhibits a high areal capacitance of 153.34 mF cm−2 and volumetric capacitance of 191.66 F cm−3 at 10 mV s−1, representing one of the highest values among all carbon-based MSC devices. These findings suggest that the developed renewable, flexible, mesoporous cellulose membrane holds great promise in the practical applications of flexible, solid-state, portable energy storage devices that are not limited to supercapacitors.

SDS-PAGE represents a quick and simple method for qualitative and quantitative analysis of protein and protein-containing conjugates, mostly pegylated proteins. PEG-maleimide (MAL) is frequently used to site-specifically pegylate therapeutic proteins via free cysteine residue by forming a thiosuccinimide structure for pursuing homogeneous products. The C-S linkage between protein and PEG-MAL is generally thought to be relatively stable. However, loss of intact PEG chain in routine SDS-PAGE analysis of PEG-maleimide modified protein was observed. It is a thiol-independent thioether cleavage and the shedding of PEG chain exclusively happens to PEG-MAL modified conjugates although PEG-vinylsulfone conjugates to thiol-containing proteins also through a C-S linkage. Cleavage kinetics of PEG40k-MAL modified ciliary neurotrophic factor showed this kind of degradation could immediately happen even in 1 min incubation at high temperature and could be detected at physiological temperature and pH, although the rate was relatively slow. This may provide another degradation route for maleimide-thiol conjugate irrespective of reactive thiol, although the specific mechanism is still not very clear for us. It would also offer a basis for accurate characterization of PEG-MAL modified protein/peptide by SDS-PAGE analysis.

Departure from nucleate boiling (DNB) type critical heat flux (CHF) is one of most important thermal criteria for nuclear reactor design. Concerning on the typical chopper-cosine heat flux profile at reactor core, it is of great significance to predict the CHF under non-uniform heating conditions for reactor design and the performance promotion of reactor system. Some correction factors are proposed for the prediction of CHF with non-uniform axial power shapes. In this study, a mechanistic DNB-type CHF model has been developed on the basis of liquid sublayer dryout mechanism. The non-uniform axial heat flux is taken into account of upstream memory effect on boiling crisis in this model. The predictions of present model and Tong’s non-uniform heat flux shape factor method are compared with the experimental results in the vertical tube with chopper-cosine axial heat flux distributions. The comparison results show the present model has fairly good prediction capability for DNB-type CHF under non-uniform heating condition.Copyright © 2014 by ASME

Arginine has been widely used as low molecular weight additive to promote protein refolding by suppressing aggregate formation. However, methods to investigate the role of arginine in protein refolding are often limited on protein's global conformational properties. Here, hydrogen/deuterium exchange mass spectrometry (HDX-MS) was used to study the effects of arginine on recombinant human granulocyte colony-stimulating factor (rhG-CSF) refolding at the scale of peptide mapping. It was found that deuteration levels of rhG-CSF refolded with arginine was higher than that without arginine during the whole refolding process, but they became almost the same when the refolding reached equilibrium. This phenomenon indicated that arginine could protect some amide deuterium atoms from being exchanged with hydrogen, but the protection diminished gradually along with refolding proceeding. Enzymatic digestion revealed six particular peptides of 16-47,72-84, 84-93,114-124,145-153 and 154-162 were mainly responsible for the deuteration, and all of them dominantly located in protein's alpha-helix domain. Furthermore, thermodynamics analysis by isothermal titration calorimetry provided direct evidence that arginine could only react with denatured and partially refolded rhG-CSF. Taking all of the results together, we suggest that arginine suppresses protein aggregation by a reversible combination. At the initial refolding stage, arginine could combine with the denatured protein mainly through hydrogen bonding. Subsequently, arginine is gradually excluded from protein with protein's native conformation recovering. (C) 2014 Elsevier B.V. All rights reserved.

PEGylated hemoglobin (Hb) is a promising oxygen therapeutic agent for clinical application. However, it suffered from structural perturbation, functional instability and methemoglobin (metHb) formation.To improve the structural, functional, physical and anti-oxidation properties of the PEGylated Hb.PEGylation of Hb with CO binding (HbCO) was conducted using maleimide and acylation chemistry, respectively. Physical and chemical parameters were measured for Hb samples. The circular dichroism spectra, dynamic light scattering and analytical ultracentrifugation were used to investigate the structure and conformation of PEGylated HbCO.CO binding can inhibit the autoxidation of the PEGylated Hb, structurally stabilize its tetramer and improve its thermal and pH stability. Importantly, the circular dichroism spectra showed that CO binding can decrease the structural perturbation of Hb induced by PEGylation. The PEGylated HbCO with CO release showed slightly higher oxygen-delivery capacity than the PEGylated Hb. The PEGylated HbCO did not show metHb formation after 30-day storage at 4°C.CO binding structurally stabilized the PEGylated Hb, abolished its metHb formation, and significantly increased its physical stability. In particular, it also avoided the perturbation of PEG chains on the heme microenvironment. The functional property of the PEGylated HbCO can be maintained during its long-term storage, which is of great significance for field transfusion.

Chongqing City in China has suffered from serious air pollution and acid rain caused by low graded raw coal (sulfur=ca. 3≈5%, ash=ca. 30%) combustion. In this paper, the situation of atmospheric pollution and acid rain in Chongqing are discussed, the reduction efficiency for sulfur dioxide (SO2) with the bio-briquetting of the raw coal that is one of countermeasures for emission control of air pollutants due to domestic consumes was determined. The research indicated that the frequency of acid rain was high, more than 50% at urban area, and its pH was low, about 4.5. Under our experimental conditions, the reducing efficiency of sulfur SO2 emission from high sulfur coal-biomass briquette amounted to 87%. The field investigation indicated that SO2 indoor concentrations in case of using bio-briquette dropped to 1/2≈1/3 of the raw coal.

The two-dimensional hydrodynamic discharge model is presented based on the hydrodynamic mechanics theory and gas discharge characteristics, with a uniform applied field, during the discharge process of SF6 at atmospheric pressure, and it is established by adopting Poisson equation in conjunction with the continuity equations for electrons, negative and positive ions, besides, the photo - ionization is also considered in the proposed model. The Finite Difference-Flux Corrected Transport technique is used in numerical simulation of discharge process, in order to improve the accuracy and efficiency. Then the gap-space electric field distribution, space ions distribution are revealed from the microscopic mechanism, and the evolutions of the charged particles are obtained in detail, furthermore, the tempo-spatial critical point of the avalanche-to-streamer in this model is discovered, the influence of applied voltage and initial plasma charge density on the streamer characteristic are also investigated. The results show that the initial plasma charge density is closely related to the gradient slope of the gap-space electric field distribution and electron density distribution, meanwhile, the electric field strength, the propagation velocity and charge density of the streamer head increase with increasing applied voltage. Above results analysis can be in favor of further study of the discharge mechanism and provide the theoretical support for electrical equipment designed.

Previous studies demonstrated that hydrophobic proteins could be PEGylated in organic phase rather than water phase. It is still not known what the difference is for a hydrophilic protein's PEGylation in these two different phases. In this study, granulocyte colony stimulating factor (G-CSF) was dissolved in neat dimethyl sulfoxide (DMSO) and was PEGylated. In comparison with the PEGylation in water solution, the PEGylation degree in the organic solvent increased by 33% and 42% for PEG-maleimide (MAL-PEG) and PEG-succinimidyl carbonate (SC-PEG) respectively. Structure analysis revealed that the protein was unfolded in DMSO, which could make the PEGylated sites of G-CSF easily accessible. The hydrolysis half-life in water solution was 40 min and 9 h for SC-PEG and MAL-PEG respectively. However, in DMSO solvent, PEGs were very stable and no hydrolysis could be detected. Stopped-flow demonstrated that the conjugation speed of G-CSF by MAL-PEG and SC-PEG in DMSO were 1.6 x 10(4) and 2 x 10(2) times faster than those in aqueous solution. The remarkable acceleration could mainly be attributed to an increase of protein nucleophilicity in DMSO. The results of this study could be referential to industrial application where the cost of PEG reagents and the speed of reaction on large scale are very important. (C) 2013 Elsevier B.V. All rights reserved.

The aims are to develop new kinds of insulating mediums being technically as well as economically attractive and fully understand the electronegative gas characteristic of endurance voltages, mechanism of partial discharge and widen their using areas in the high voltage system. The article presents the experiment procedures, contents are involved in as follow: needle-needle, needle-plane, sphere-plane, sphere-sphere and needle-sphere electrode systems, and industrial purity SF 6 and its mixture combining N 2 are filled into the experiment chamber in different partial pressure and applied the impulse voltages in different pressures. The mechanism of initiated PD potentials and breakdown of the SF 6 and SF 6 /N 2 have been analyzed theoretically according to the molecular structure and physical characteristics of the electro-negative gases, the research works are helpful to develop and widen using fields of the SF 6 and its mixtures in high voltage engineering.

The infrared (IR) spectrum of protonated azulene (AzuH(+), C10H9+) has been measured in the fingerprint range (600-1800 cm(-1)) by means of IR multiple photon dissociation (IRMPD) spectroscopy in a Fourier transform ion cyclotron resonance mass spectrometer equipped with an electrospray ionization source using a free electron laser. The potential energy surface of AzuH(+) has been characterized at the B3LYP/6-311G** level in order to determine the global and local minima and the corresponding transition states for interconversion. The energies of the local and global minima, the dissociation energies for the lowest-energy fragmentation pathways, and the proton affinity have been evaluated at the CBS-QB3 level. Comparison with calculated linear IR absorption spectra supports the assignment of the IRMPD spectrum to C4-protonated AzuH(+), the most stable of the six distinguishable C-protonated AzuH(+) isomers. Comparison between Azu and C4-AzuH(+) reveals the effects of protonation on the geometry, vibrational properties, and the charge distribution of these fundamental aromatic molecules. Calculations at the MP2 level indicate that this technique is not suitable to predict reliable IR spectra for this type of carbocations even for relatively large basis sets. The IRMPD spectrum of protonated azulene is compared to that of isomeric protonated naphthalene and to an astronomical spectrum of the unidentified IR emission bands. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3262720]

Acid rain may cause soil acidification possibly leading to indirect forest damage. Assessment of acidification potential of atmospheric deposition is problematic where dry and occult deposition is significant. Furthermore, uncertainty is enhanced where a substantial part of the potential acidity is represented by deposition of ammonium (NH(4)(+)) since the degree of assimilation and nitrification is not readily available. Estimates of dry deposition based on deposition velocity are highly uncertain and the models need to be verified or calibrated by field measurements of total deposition. Total deposition may be monitored under the forest canopy. The main problem with this approach is the unknown influence of internal bio-cycling. Moreover, bio-cycling may neutralize much of the acidity by leaching of mainly K(+). When the water percolates down into the rooting zone this K(+) is assimilated again and acidity is regenerated. Most monitoring stations only measure deposition. Lacking measurements of output flux of both NH(4)(+) and NO(3)(-) from the soil one cannot assess current net N transformation rates. Assumptions regarding the fate of ammonium in the soil have strong influence on the estimated acid load. Assuming that all the NH(4)(+) is nitrified may lead to an overestimation of the acidifying potential. In parts of the world where dry deposition and ammonium are important special consideration of these factors must be made when assessing the acidification potential of total atmospheric loading. In China dry and occult deposition is considerable and often greater than wet deposition. Furthermore, the main part of the deposited N is in its reduced state (NH(4)(+)). The IMPACTS project has monitored the water chemistry as it moves through watersheds at 5 sites in China. This paper dwells at two important findings in this study. 1) Potassium leached from the canopy by acid rain is assimilated again upon entering the mineral soil. 2) Nitrification apparently mainly takes place in forest floor (H- and O-) horizon as NH(4)(+) that escapes this horizon is efficiently assimilated in the A-horizon. This suggests that the potential acidification capacity of the deposition may be found in the throughfall and forest floor solution by treating K(+) and NH(4)(+), respectively, as acid cations in a base neutralization capacity (BNC) calculation.