Characterization of the dissociation pathways of dichloromethane and glutathione in dichloromethane dehalogenase

Dichloromethane(DCM)dehalogenase stands as a crucial enzyme implicated in the degradation of methylene chloride across diverse environmental and biological contexts.However,the unbinding pathways of ligands from DCM dehalogenase remain unexplored.In order to gain a deeper understanding of the binding sites and dissociation pathways of dichloromethane(DCM)and glutathione(GSH)from the DCM dehalogenase,random accelerated molecular dynamics(RAMD)simulations were performed,in which DCM and GSH were forced to leave the active site.The protein structure was predicted using Alphafold2,and the conformations of GSH and DCM in the binding pocket were predicted by docking.A long equilibrium simulation was conducted to validate the structure of the complex.The results show that GSH is most commonly observed in three main pathways,one of which is more important than the other two.In addition,DCM was observed to escape along a unique pathway.The key residues and protein helices of each pathway were identified.The results can provide a theoretical foundation for the subsequent dissociation mechanism of DCM dehalogenase.

Effect of carbon fiber on thermal properties of n-Docosane phase change materials

The improvement of the heat transfer rate of phase change material（PCM）is studied by mixing with carbon fiber（CF）which is a good heat conductor.The composite PCM is prepared by blending CF and n-Docosane and its thermal performance is tested using the method of differential scanning calorimetry（DSC）analysis and thermogravimetric/differential thermal analysis（TG/DTA）.In addition,the influence of the mixing amount and the length of CF on the thermal conductivity of n-Docosane are investigated.The results show that CF can significantly improve the heat transfer rate of n-Docosane,and the mixing amount and the length of CF are two influence factors.The heat storage and release rates increase with the increase in the mixing amount of CF.Moreover,the melting point of n-Docosane is increased from 40.2 to 50.8 ℃ after being mixed with CF.The heating time is decreased from 720 to 660 s by mixing with 6% of CF,and is decreased to 600 s by mixing with 10% of CF.

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Occurrence and distribution of hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) in the Han River system, South Korea

We investigated the occurrence and distribution of terrestrial-derived hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) in the Han River system and their potential impact on the application of the ring index of OH-GDGTs(RI-OH) as a sea surface temperature(SST) proxy in the eastern Yellow Sea. Thereby, we analyzed various samples collected along the Han River and from its surrounding areas(South Korea, n = 34). The OHGDGTs were found in all samples investigated. OH-GDGT-0 was the dominant OH-GDGT component in the estuary and marine samples while OH-GDGT-2 was generally dominant in the soils, the lake sediments and the river suspended particulate matter(SPM). Our results thus suggests a possible warm bias of the RI-OH-derived summer SSTs in the coastal zone to which a large amount of terrestrial organic matter is being supplied. Further studies are necessary to better assess the applicability of the RI-OH proxy in the eastern Yellow Sea.

INTRATHECAL GLYCINE SIGNIFICANTLY DECREASES THE MINIMUM ALVEOLAR CONCENTRATION OF ISOFLURANE IN RATS

To evaluate the effect of intrathecal administration of glycine on the minimum alveolar concentration （MAC） of isoflurane in rats. Methods Intrathecal catheters were implanted in 40 adult male rats anesthetized with isoflurane. Baseline MAC of isoflurane was measured during the infusion of artificial cerebrospinal fluid （CSF） alone. Subsequently, 10, 40, 80, 160, and 300 mmol/L of glycine dissolved in artificial CSF were infused for two hours at the same rate as under control conditions, and MAC for isoflurane was re-determined. Results Intrathecal administration of glycine produced a significant, dose-dependent decrease in MAC for isoflurane （up to -65.2% ± 16. 2% ）. Conclusions Intrathecal administration of glycine decreases anesthetic requirement. This result supports the idea that glycine receptors may be important to the immobilizing effect of anesthetics that enhance glycine receptor function such as isoflurane.

Nano-indentation profiles of intrinsic hardness and modulus of films based on silsesquioxane modified with titanium tetrabutoxide

This study is to analyze the influence of the modifier, 5～25 wt % titanium tetrabutoxide (TBO), on the hardness and elastic modulus of the films based on SSO deriving from hydrolytic condensation of (3-glycidoxypropyl)trimethoxysilane (GPMS) and vinyltrimethoxysilane (VMS), by the continuous stiffness measurement (CSM) technique of an instrumented-indentation testing (IIT) device. Films were synthesized by adding the stoichiometric amount of ethylenediamine (EDA) and benzoyl proxide (BPO) to SSO solutions in ethanol, dip-coating over glass substrates, and curing using an appropriate thermal cycle. Intrinsic values of hardness and elastic modulus were determined with the average values in “plateau region” from “four-layer” explanation. And the brittle index of the modified coating systems was analyzed.

Distinct distribution revealing multiple bacterial sources for 1-Omonoalkyl glycerol ethers in terrestrial and lake environments

The 1-O-monoalkyl glycerol ethers （MAGEs） were initially viewed as the biomarkers for sulfate-reducing bacteria （SRB） me- diating anaerobic oxidation of methane in the marine environments. However, limited information is known about their distri- bution in terrestrial and other aquatic settings including soils, fresh water lakes, and cave sediments, which may obscure our understanding of their biological sources. Here we found that MAGEs were ubiquitous but differed obviously in distributional pattern among those environments. The surface soils are dominated generally by iC15：0-MAGE, followed by nCI6：o-MAGE whereas the lake sediments show the opposite, resulting in significantly higher iC15：0/nC16：0 ratios in soils than in lake sedi- ments. The cave deposits are characterized by considerably higher proportions of branched MAGEs than the former two envi- ronments. The logarithm of iC15：0/aC15：0 ratio shows a significant negative correlation with soil pH, likely reflecting an adapta- tion of microbial cell membrane to change in the ambient proton concentration. The MAGE profiles in cultured bacteria cannot fully explain the MAGE distribution in all the samples analyzed. Therefore, MAGEs in soil, lake sediments, and cave deposits likely have additional biological source（s） other than SRB and cultured MAGE-producing bacteria. The difference in MAGE pattern among environments is likely to be attributed to change in microbial communities.

Distribution of branched glycerol dialkyl glycerol tetraethers in soils on the Northeastern Qinghai-Tibetan Plateau and possible production by nitrite-reducing bacteria

Branched glycerol dialkyl glycerol tetraethers （bGDGTs） are ubiquitous and abundant in soils, but their sources remain elusive. Recent studies demonstrate that the distributions of bGDGTs are sensitive to various environmental factors. In an effort to understand how and to what extent soil moisture （expressed as soil water content （SWC） or mean annual precipita- tion （MAP）, pH and temperature may impact the distribution of bGDGTs, and to shed more light on the biological sources of bGDGTs in cold and arid regions, we investigated the distribution of bGDGTs as well as bacterial 16S rRNA gene and func- tional genes involved in the N cycle （including amoA, nirS and nirK） in 41 surface soil samples from around Lake Qinghai and east of Qaidam Basin on the Northeastern Qinghai-Tibetan Plateau. We found that lower soil moisture reduced the fractional concentrations of cyclic bGDGTs and thus the cyclisation ratio of branched tetraethers （CBT） index correlated negatively with SWC and MAP, suggesting that soil moisture is an important factor controlling bGDGT distributions in soils in this add and semi-add region. Two subgroups of bGDGTs were assigned on the basis of cluster analysis, and bGDGT indices behaved dif- ferently in the two groups, hinting at different biosynthetic mechanisms for bGDGTs under different environmental conditions. Real time PCR results showed that nirS and nirK genes correlated significantly with the concentration of bGDGTs, suggesting that the nirS- or nirK-encoding bacteria involved in denitrification might potentially be an additional biological source for soil bGDGTs （besides Acidobacteria）. Moreover, our results also support the application of new indices based on 5-methyl bGDGTs and 6-methyl bGDGTs in reconstructing past temperature and pH variations in this region.

Synthesis of aziridines by visible-light induced decarboxylative cyclization of N-aryl glycines and diazo compounds

A visible-light induced decarboxylative aza-Darzens reaction between N-aryl glycines and diazo compounds was developed, which affords various mono-substituted aziridines in good yields.

Effect of glutathione on in vivo biodistribution and clearance of surface-modified small Pd nanosheets

Plasmonic Pd nanosheets have been emerging as promising materials for application in near-infrared(NIR) photothermal therapy(PTT) of cancer. However, animal in mice studies indicated that the original synthesized poly(vinylpyrrolidone)(PVP)-protected small Pd nanosheets(Pd-PVP) and some further surface-modified small Pd nanosheets such as Pd-PEG(SH) easily accumulated in reticuloendothelial system(RES) organs(liver, spleen, etc.) and were difficult to be cleared from these organs quickly. In the work, we surprisingly found that glutathione(GSH) could promote the clearance of surface-modified small Pd nanosheets(e.g. Pd-PVP, Pd-PEG(SH) and Pd-GSH) from the RES organs efficiently. The effects of GSH on the biodistribution and clearance of different surface-modified Pd nanosheets were investigated. Our results indicated that these surface-modified Pd nanosheets with or without GSH added caused no morbidity at target primary organs, and GSH can promote the clearance of different surface-modified Pd nanosheets in the order of Pd-PVP≈Pd-PEG(SH)>Pd-GSH. This study suggests that glutathione could be an attractive reagent for promoting nanomaterials eliminated from the reticuloendothelial systems(RES).