Use of Sequential, Single and Kinetic Extractive Schemes to Assess Cadmium (Cd) and Lead (Pb) Availability in Vietnamese Urban Soils

Modified BCR sequential extraction, single equilibrium-based EDTA extraction and kinetic fractionation were used for estimating the Pb and Cd availability in a series of soil samples from 3 sites located in urban areas of Hanoi (Vietnam). These schemes were compared to identify a simple, rapid and cheap protocol for routine estimation of Pb and Cd remobilizable fraction and the related potential risk. The comparison of these three approaches revealed their convergence in terms of mobility patterns observed for Pb and Cd. Cd was characterized by higher extractibality and mobility whatever the approach. Pb was distinguished of Cd by its high association to Feoxides, lower extractability, lower rate of desorption and then lower mobility. For this environmental scenario, EDTA single scheme at equilibrium could be suggested as the best suited and a simple protocol for determination of the labile pool of Cd and Pb. The pseudo-total concentrations of Pb and Cd are actually below the Vietnamese standard level, contrary to the results obtained by other authors for agricultural soils at other urban sites of Hanoi.

Spectroscopic and molecular docking studies on the binding mechanism of Mobic and lipase

Under simulated physiological conditions (pH=7.40), the interaction between non-steroidal anti-inflammatory drug Mobic and lipase was studied by fluorescence spectra, ultraviolet absorption spectra, circular dichroism spectra and computer simulation technique. The experimental results showed that Mobic could quench the fluorescence of lipase by static quenching, and the binding site number is about 1. According to F¨orster’s theory of non-radiation energy transfer, the binding distance between Mobic and lipase was obtained, r<7 nm, which indicated that there was non-radiation energy transfer in the system. The thermodynamic parameters were obtained from van’t Hoff equation, Gibbs free energy -G<0, indicating that the reaction between them was spontaneous,-H<0,-S>0, indicating that hydrophobic force played a major role in the formation of Mobic and lipase complex. The results of synchronous fluorescence spectra, UV spectra and circular dichroism spectra showed that Mobic changed the conformation of lipase. The molecular docking results showed that the binding position of Mobic was close to the active center, indicating that Mobic could change the microenvironment of amino acid residues at the active center of lipase catalysis. The results of docking showed that there was hydrogen bond between Mobic and lipase, so the interaction between Mobic and lipase was driven by hydrophobic interaction and hydrogen bond.

Characteristics of the Acute Biotoxicity and the Toxic Factors of Tributaries of Baiyangdian Lake

This study aimed to combine the acute biotoxicity test with physic-chemical analysis to pinpoint the toxic factors of river surface water.Water samples were collected from six sampling sites along Fu River,the main tributary of Baiyangdian Lake(China),in the spring and summer of 2018.Acute biotoxicity test was carried using luminous bacteria(Vibrio qinghaiensis sp.Q67)and zebrafish(Brachydanio rerio).The results showed that the river water exerted certain toxic effects on zebrafish and luminous bacteria and the latter was more sensitive to the toxicity of river water;the toxicity to luminous bacteria at the 6 sampling sites was higher in summer than in spring.According to the Pearson correlation coefficient analysis,COD,NH3-N,Zn and Cu were the pollution factors that gave rise to the acute toxicity of the surface water and thus should be put under special control.

Spectroscopic study on the mechanism of meloxicam and α-amylase

In order to explore the mechanism of action of meloxicam and α-amylase. The interaction between the rheumatoid arthritis drug meloxicam and α-amylase was studied by fluorescence spectroscopy, synchronous fluorescence spectroscopy and molecular docking under the experimental conditions of pH=6.80. The results showed that meloxicam was able to effectively quench the endogenous fluorescence of α-amylase in a static quenching form a 1:1 complex and change the conformation of α-amylase. Thermodynamic results indicated that the main type of meloxicam and α-amylase system was hydrophobic interaction. Molecular docking indicated that the binding system had hydrogen bonds in addition to hydrophobic interaction and meloxicam was surrounded by the active amino acid residues Trp13 and Trp263 of α-amylase, which changed the microenvironment of amino acid residues at the active center of α-amylase. By establishing the binding model, it can be seen that the protein binding rate W(B) of meloxicam to -amylase was 2.76%-41.79% under the experimental conditions. The results showed that the binding of meloxicam to α-amylase had an effect on the number of free -amylase. The drug binding rate W(Q) of the system was 2.76%-1.67%, which indicated that the combination of α-amylase and meloxicam would not affect the efficacy of meloxicam.

Determination of Hg in soil by ultrasonic slurry sampling hydride generation atomic fluorescence spectrometry

Ultrasonic aided slurry sampling hydride generation atomic fluorescence spectrometry （USS-HG-AFS） was developed for the determination of Hg in soil samples from a sewage-irrigated farm. 500 mg grounded soil was suspended in agar solution by an ultrasound water bath before the HG-AFS determination. The results for the reference material of soil （serial number GBW-07411） agreed satisfactorily with the certified values. Results obtained by the developed procedure compared well with those after traditional acid digestion of samples. The detection limit are 6.7ngL-1 for Hg respectively, with average relative standard deviation values of 6.4% for analysis of a series of soil samples of different origin. The recoveries of the anatytes varied in the range from 95 to 107%. This observation has stimulated interest in fast, accurate and sensitive analytical methods for determination of metals in soil.

Determination of Cadmium in TSP, PM10 in urban areas by hydride generation atomic fluorescence spectrometry

In this paper, two different diameter particles （TSP, PM10） were collected by TH-16A four-channels classification air sampler. The samples were treated by HNO3. Analysis of cadmium was carried out by hydride generation atomic fluorescence spectrometry （HG-AFS） method, and distribution proportions of elements in four phases were calculated. This method was based on the reaction of cadmium with 1.5% （m/v） KBH4 solution and 0.5% KOH（m/v） solution to form the hydride gas in medium of 2% （v/v） HCl. The detection limit for cadmium as low as 0.008μg/L was obtained. The lineally correlation coefficient was 0.99992. The relative standard deviation （n=5, C=1.00μg/L） was 3.26%. The proposed method was applied for the determination of cadmium in atmosphere aerosol samples and the recoveries in the range of 95-102.2% were obtained. This method was simple, rapid, less matrix interference and high sensitivity.

Z-scheme Bi_(4)O_(5)Br_(2)/NH_(2)-MIL-125(Ti)heterojunctions enable exceptional visible photocatalytic degradation of organic pollutant

One key strategy to enhance photocatalytic performance is to improve the transfer and separation efficiency of photogenerated carriers by building optimized heterojunctions.Herein,novel Bi_(4)O_5Br_(2)/NH_(2)-MIL-125(Ti)Z-scheme heterojunctions are fabricated and used as photocatalysts for organic pollutant photodegradation.The NH_(2)-MIL-125(Ti)nanosheets are exfoliated via a self-developed alkali solution stripping approach and then uniformly decorated on Bi_(4)O_(5)Br_(2).The as-prepared Bi_(4)O_(5)Br_(2)/NH_(2)-MIL-125(Ti)presents more than 90%degradation of various pollutants,outperforming the counterpart individual ones.The various characterization results suggest that the enhanced degradation rate is due to the more intimate face-to-face interfacial contact of the lamellar Z-scheme heterojunction materials,in which the migration path of carriers from the material's interior to the surface can be reduced,in turn enhancing migration efficiency and separation capability significantly.A possible photocatalytic reaction mechanism is proposed based on the photoelectric behaviors,radical trapping experiments and liquid chromatography mass spectrometry analysis.This work promotes the development of new photocatalytic materials for heterojunctions with face-to-face interfacial contacts,as well as the effective purification of wastewater in environmental remediation.

Biosafety materials:Ushering in a new era of infectious disease diagnosis and treatment with the CRISPR/Cas system

Despite multiple virus outbreaks over the past decade,including the devastating coronavirus disease 2019(COVID-19)pandemic,the lack of accurate and timely diagnosis and treatment technologies has wreaked havoc on global biosecurity.The clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated proteins(Cas)system has the potential to address these critical needs for tackling infectious diseases to detect viral nucleic acids and inhibit viral replication.This review summarizes how the CRISPR/Cas system is being utilized for the treatment and diagnosis of infectious diseases with the help of biosafety materials and highlights the design principle and in vivo and in vitro efficacy of advanced biosafety materials used to deal with virus attacks.

Kinetics and Mechanism of Oxidation of Some Diols by Dihydroxydiperiodatoargentate（Ⅲ） in Alkaline Medium

The kinetics of oxidation of ethylene glycol and 1,3-butylene glycol by dihydroxydiperiodatoargentate（Ⅲ） in alkaline medium have been studied by spectrophotometry in the range of 298.2-318.2 K. It is shown that the reaction was first order with respect to each reductant and Ag（Ⅲ）, and kobs increased with an increase of [OH^-]. A plausible mechanism of reaction involving a pre-equilibrium of adduct formation between complex and reductants was proposed, which could be applied to explain all experimental phenomena, and the activation parameters of the ratedetermining step have been also calculated.

Preparation,Crystal Structure and Fungicidal Activity of N-(5-(benzofuranol-7-oxymethyl)-1,3,4-thiadiazol-2-yl)amide Compounds

A variety of new N-(5-(benzofuranol-7-oxymethyl)-1,3,4-thiadiazol-2-yl)amide compounds(8a-i)were synthesized through four steps from benzofuranol as raw materials.The crystal structure of compound 8a(C17H21N3O3S,Mr=347.43)was measured by X-ray diffraction,which was classified as monoclinic system,Z=4,V=1742.72(8)Å3,Dc=1.324 Mg/m3,F(000)=736,S=1.03,μ=0.21 mm-1,space group P21 with a=9.9177(3),b=8.9519(2),c=19.8679(5)Å,the final R=0.035 and wR=0.105 for 3873 observed reflections(I>2σ(I)).The X-ray structure presented N(3)-H(3)···N(2)and C(6)-H(6)···O(3)intermolecular hydrogen bonds,which acted as an important role in stabilizing the crystal structure.Additionally,preliminary biological assay on compound 8a showed good fungicidal activity in vivo,with the inhibition of 75%against Pseudoperonospora cu-bensis at 200 mg/L.

Open tubular capillary electrochromatography with block co-polymer coating for separation of β-lactam antibiotics

A new open-tubular capillary electrochromatography (OT-CEC) method for analysis of β-lactam antibiotics has been developed with unique block co-polymer coating. To obtain the highly ordered block polymer chains, reversible addition fragmentation chain transfer radical polymerization method was used to synthesize poly (maleic anhydride-styrene-N-isopropylacrylamide). The prepared block copolymer coating was characterized with NMR, fourier transform infrared spectroscopy and scanning electron microscope. Several key separation factors of OT-CEC, which including polymer amount,stability of the coating, temperature, species of organic additives, buffer pH and concentration, were investigated in detail. Our results indicated that the separation efficiency was improved greatly with the coating capillary and the three test analytes could be baseline separated. Then, the separation mechanism was briefly explored. Moreover, the proposed OT-CEC method displayed promising quantitative analysis property of the three test analytes with good linearity (R2>0.99), repeatability (relative standard deviations <0.9%) and high recovery (95.4%-106.2%). Further, the assay was applied in monitoring the three test β-lactam antibiotics (cephradine, cephalexin and amoxicillin) in serum samples, providing a useful platform for construction of novel polymer coatings in OT-CEC system and for analysis of drugs in real bio-samples.

Improved Synthesis of 1,3-Diaryl-2-propen-1-one Oxime in the Presence of Anhydrous Sodium Sulfate

Synthesis of 1,3-diaryl-2-propen-1-one oxime via the condensation of 1,3-diaryl-2-propen-1-one with hydroxylamine hydrochloride in the presence of anhydrous sodium sulfate was carried out in refluxing EtOH for 2-4 h in 83%-93% yields. The significant features of the present procedure include higher yield, shorter reaction time, reduced molar ratio of hydroxylamine hydrochloride to substrate, compared to the reported literature method.

A highly selective and sensitive upconversion nanoprobe for monitoring hydroxyl radicals in living cells and the liver

Excessive reactive oxygen species(ROS)would attack living cells and cause a series of oxidative stress related diseases,such as liver damage.Hydroxyl radicals(·OH)are currently known as one of the most toxic and harmful free radicals to organisms.Therefore,studies involving hydroxyl radicals have become important research topics in the fields of biology,biochemistry,and biomedicine.In addition,imaging of analytes using upconversion nanoparticles(UCNPs)possesses significant advantages over that using general fluorescent dyes or nanoparticles due to its high spatial resolution,reduced photodamage,and deep tissue penetration properties.Herein,we designed a highly selective and sensitive hydroxyl radical nanoprobe based on the luminescence resonance energy transfer between upconversion nanoparticles and methylene blue(MB).The concentration of·OH could be determined by the fluorescence recovery of the UCNPs due to the oxidative damage of MB.Using this nanoprobe,the·OH in living cells or in liver tissues could be monitored with high sensitivity and selectivity.

基于转化-合金化机制的钠离子电池PbSe@CNTs负极材料

钠离子电池作为新型的储能电池体系因钠资源储量丰富、成本低廉等优势有望填补锂离子电池在某些应用领域的空缺,非常适用于大规模储能领域.然而,高容量储钠负极材料仍然需要进一步研究.本文以废旧铅酸电池的回收铅和商业化硒粉为原料,采用机械球磨法制备了纳米硒化铅与碳纳米管(PbSe@CNTs)的复合材料.碳纳米管网络缠绕在PbSe纳米粒子上,可有效抑制纳米粒子的团聚,同时提高了电子导电性.纳米级的PbSe和拓扑结构的CNTs有利于电解液的渗透,缩短了Na+和电子的传输路径,缓解了脱嵌钠过程中的机械应变,提高了倍率和长循环稳定性能.PbSe@CNTs电极在20 mA g^(-1)电流密度下具有597 mA h g^(-1)的可逆比容量,在100 m A g^(-1)循环100圈仍保持458.9 mA h g^(-1)的可逆比容量,容量保持率为88%.通过X射线衍射和拉曼光谱分析,证实了PbSe的储钠机理为两步转化-合金化过程,反应方程式为PbSe+5.75Na++5.75e-?0.25Na15Pb4+Na2Se.