同心圆式反应器中精确调控和连续制备β-四钼酸铵

采用同心圆式反应器制备β-四钼酸铵,研究制备过程中Mo离子聚合形态和微观结构受溶液酸度影响的变化规律。结果表明,将溶液的pH值控制在2.5以下可以得到四钼酸铵晶体;采用NH_(3)·H_(2)O将溶液pH值调回至3.0有利于细粒钼酸铵结晶的溶解,并促进七钼酸铵向四钼酸铵结晶的转变;降低(NH_(4))_(4)Mo_(4)O_(12)(O_(2))2·2H_(2)O晶体与结晶母液的接触时间有利于获得β-(NH_(4))_(2)Mo_(4)O_(13)结晶。基于钼的聚合机理,设计多个格区的同心圆反应器,实现钼酸铵结晶的分区域调控。通过调控硝酸、氨水和含晶种的母液在各格区中加入的位置和时机,可制备出优质的β-(NH_(4))_(2)Mo_(4)O_(13)结晶。

Primary antibiotic resistance of Helicobacter pylori strains isolated from patients with dyspeptic symptoms in Beijing: A prospective serial study

AIM:To determine the resistance patterns of Helicobacter pylori(H.pylori) strains isolated from patients in Beijing and monitor the change of antibiotic resistance over time.METHODS:In this prospective,serial and crosssectional study,H.pylori cultures were successfully obtained from 371 and 950 patients(never receiving eradication) during 2009-2010 and 2013-2014,respectively.Resistance to amoxicillin,clarithromycin,metronidazole,levofloxacin,tetracycline,and rifampicin was determined by Epsilometer test.RESULTS:The resistance rates of isolates obtained during 2009-2010 were 66.8%,39.9%,34.5%,15.4%,6.7%,and 4.9% to metronidazole,clarithromycin,levofloxacin,rifampicin,amoxicillin and tetracycline,respectively; and the corresponding rates for isolates during 2013-2014 were 63.4%,52.6%,54.8%,18.2%,4.4% and 7.3%,respectively.The resistance rates to clarithromycin and levofloxacin were significantly increased after four years.In 2009-2010,14.6% of H.pylori isolates were susceptible to all tested antibiotics,with mono(33.7%),double(28.3%),triple(16.7%),quadruple(6.2%),quintuple(0.3%) and sextuple resistance(0.3%) also being detected.In 2013-2014,9.4% were susceptible to all tested antibiotics,and mono(27.6%),double(28.4%),triple(24.9%),quadruple(7.3%),quintuple(2.3%) and sextuple resistance(0.1%) was also observed.More multiple resistant H.pylori isolates were found during 2013-2014.Gender(to levofloxacin and metronidazole),age(to levofloxacin) and endoscopic findings(to clarithromycin) were independent factors influencing antibiotic resistance.CONCLUSION:H.pylori resistance to commonly used antibiotics in Beijing is high with increased multiple antibiotic resistance.

Research and development trends of hydrometallurgy:An overview based on Hydrometallurgy literature from 1975 to 2019

Modern hydrometallurgy has been developing for more than 100 years and the related articles keep piling up.Based on a bibliometric analysis of the articles in Hydrometallurgy,the most authoritative journal in the field of hydrometallurgy,we try to catch the research and development trends from a global perspective.Firstly,keywords burstness shows that rare earth,recycling,lithium,ionic liquid,and thorium are the hotspots in recent years,and the economic and technological reasons behind them were discussed in depth.Secondly,the proportion of biohydrometallurgy grows fast from 5%to 13%and the related articles are almost all about bioleaching.There are some new directions such as direct preparation of materials in hydrometallurgical processes and ion-imprinted techniques.Thirdly,the advanced instrument analysis methods such as XAFS(X-ray absorption fine structure),gene sequencing,and micro-CT promote the deep understanding of hydrometallurgy mechanism.Finally,the cooperation network and contribution of the main institutes were mapped.

Comparative kinetic analysis of conventional and ultrasound-assisted leaching of scheelite by sodium carbonate

For further comprehending the mechanism of the intensification of ultrasound for extraction,the difference of leaching kinetics between the ultrasound-assisted and conventional sodium carbonate leaching of scheelite was studied,and the corresponding kinetic equations were established.The results indicate that the obtained apparent activation energy with or without ultrasound is same 72 kJ/mol,and both reactions are controlled by surface chemical reaction.By comparing the leaching kinetics of scheelite by Na2CO3,NaOH and Na3PO4 reactants with or without ultrasound,a general conclusion for scheelite hydrometallurgy is obtained.For the process with the formation of compact product layer,the intensification of the tungsten extraction with ultrasound mainly reflects in the stripping and elimination of product layer,corresponding to the transformation of kinetic controlling step from diffusion controlling step and reduction of apparent activation energy.For the one without compact product layer or with a loose and porous product layer,the intensification mainly embodies in the increase of frequency factor,and the controlling step and apparent activation energy of the reaction always remain constant.

Radical treatment of stage Ⅳ pancreatic cancer by the combination of cryosurgery and iodine-125 seed implantation

AIM:To investigate the therapeutic effect of radical treatment and palliative treatment in stage Ⅳ pancreatic cancer patients.METHODS:81 patients were enrolled in the study.Radical treatment was performed on 51 patients,while 30 patients were put under palliative treatment.The procedural safety and interval survival for stage Ⅳ pancreatic cancer(IS-Ⅳ) was assessed by almost 2.5 years of follow-ups.The IS-Ⅳ of patients under the two kinds of treatment,and the effects of treatment timing and frequency on IS-Ⅳ,were compared.RESULTS:The IS-Ⅳ of patients who received radical treatment was significantly longer than those who received palliative treatment(P < 0.001).The IS-Ⅳ of patients who received delayed radical or palliative treatment was longer than those who received accordingly timely treatment(P = 0.0034 and 0.0415,respectively).Multiple treatments can play an important role in improving the IS-Ⅳ of patients who received radical treatment(P = 0.0389),but not for those who received palliative treatment(P = 0.99).CONCLUSION:The effect of radical treatment was significantly more obvious than that of palliative treatment,and multiple radical treatments may contribute more to patients than a single radical treatment.

Removal of tungsten from molybdate solution by Fe-Mn binary oxide adsorbent

Considering the different geochemical enrichment behaviors of W and Mo,Fe?Mn binary oxide(FMBO),ferric hydroxide(Fe(OH)3)and manganese dioxide(MnO2)were studied to separate W from molybdate solution,respectively.The experimental results demonstrated that Fe?Mn binary oxide(FMBO)was the most suitable adsorbent for the separation.Under a wide pH(6.9?11.3)region,more than80%W removal efficiency and less than3%Mo loss could be obtained.In addition,the Fe?Mn binary oxide adsorbent can be regenerated by treating with3mol/L NaOH,and the W adsorption efficiency was retained after five adsorption?desorption?regeneration cycles.All these indicate that the Fe?Mn binary oxides have the potential for the separation of W from molybdate solution.

Proteome Analysis of Neisseria meningitidis Serogroup Strains C Associated with Outbreaks in China

Objective During 2003-2005, an outbreak of meningitis due to Neisseria meningitidis serogroup C occurred in China. With the aim to find strain clues result in the final epidemics, the ancestral strain 053442, a clinical isolate, and a carrier strain 053426 with different gene type were analyzed. Methods Clinical strain 053442 and carrier strain 053426 were cultured on GC agar plates under the same condition. Two-dimensional electrophoresis was performed using the pH 3–10 nonlinear IPG strips of 24 cm length, and all the protein spots were identified by matrix-assisted laser desorption/ionization time of flight spectrometry. Results 502 and 380 protein spots were identified in 053426 and 053442 respectively, relating to 266 and 202 different genes covering a wide range of cellular functions. The express volume and number of proteins involved in energy metabolism, protein synthesis and amino acid biosynthesis in 053426 were higher than in 053442. Virulence factor Opa, Opc and a series of proteins involved in pilus assembly and retraction were identified in 053442, which appear to be of primary importance in colonization and invasion of human cells. Compared to 053442, virulence protein species were less in 053426, with lower express volumes too. No Opa and Opc were detected in 053426. Conclusion The different protein expression profiles of the clinical strain 053442 and carrier strain 053426 in the present study provide some clues of the different pathogenicity of the two strains, which may account for result in the final epidemics.

Amino acid deletions at positions 893 and 894 of cytotoxinassociated gene A protein affect Helicobacter pylori gastric epithelial cell interactions

BACKGROUND Helicobacter pylori(H.pylori)persistently colonizes the human gastric mucosa in more than 50%of the global population,leading to various gastroduodenal diseases ranging from chronic gastritis to gastric carcinoma.Cytotoxin-associated gene A(CagA)protein,an important oncoprotein,has highly polymorphic Glu-Pro-Ile-Tyr-Ala segments at the carboxyl terminus,which play crucial roles in pathogenesis.Our previous study revealed a significant association between amino acid deletions at positions 893 and 894 and gastric cancer.AIM To investigate the impact of amino acid deletions at positions 893 and 894 on CagA function.METHODS We selected a representative HZT strain from a gastric cancer patient with amino acid deletions at positions 893 and 894.The cagA gene was amplified and mutated into cagA-NT and cagA-NE(sequence characteristics of strains from nongastric cancer patients),cloned and inserted into pAdtrack-CMV,and then transfected into AGS cells.The expression of cagA and its mutants was examined using realtime polymerase chain reaction and Western blotting,cell elongation via cell counting,F-actin cytoskeleton visualization using fluorescence staining,and interleukin-8(IL-8)secretion via enzyme-linked immunosorbent assay.RESULTS The results revealed that pAdtrack/cagA induced a more pronounced hummingbird phenotype than pAdtrack/cagA-NT and pAdtrack/cagA-NE(40.88±3.10 vs 32.50±3.17,P<0.001 and 40.88±3.10 vs 32.17±3.00,P<0.001)at 12 hours after transfection.At 24 hours,pAdtrack/cagA-NE induced significantly fewer hummingbird phenotypes than pAdtrack/cagA and pAdtrack/cagA-NT(46.02±2.12 vs 53.90±2.10,P<0.001 and 46.02±2.12 vs 51.15±3.74,P<0.001).The total amount of F-actin caused by pAdtrack/cagA was significantly lower than that caused by pAdtrack/cagA-NT and pAdtrack/cagA-NE(27.54±17.37 vs 41.51±11.90,P<0.001 and 27.54±17.37 vs 41.39±14.22,P<0.001)at 12 hours after transfection.Additionally,pAdtrack/cagA induced higher IL-8 secretion than pAdtrack/cagA-NT and pAdtrack/cagA-NE at different times after transfection.CONCLUSION Amino acid deletions at positions 893 and 894 enhance CagA pathogenicity,which is crucial for revealing the pathogenic mechanism of CagA and identifying biomarkers of highly pathogenic H.pylori.

Determination of cyclovirobuxine D in human plasma by liquid chromatography tandem mass spectrometry and application in a pharmacokinetic study

A sensitive and reliable method based on liquid chromatography tandem mass spectrometry(LC–MS/MS)for the quantitation of cyclovirobuxine D in human plasma has been developed and validated.Sample preparation by solid phase extraction was followed by separation on a CN column with a mobile phase of methanol–water(95:5,v/v)containing 0.2%formic acid.Mass spectrometric detection in the positive ion mode was carried out by selected reaction monitoring(SRM)of the transitions at m/z 403.0→372.0 for cyclovirobuxine D and m/z 325.0→234.0 for citalopram(internal standard).The method was linear in the range 10–200 ng/L with LLOQ of 10 ng/L,recovery >85%,and no significant matrix effects.Intra-and inter-day precisions were all <9% with accuracies of 94.0–104.8%.The method was successfully applied to a pharmacokinetic study involving a single oral administration of a 2 mg cyclovirobuxine D tablet to twenty-two healthy Chinese volunteers.

A highly stable and luminescent mononuclear Cu(Ⅰ)bis-{5-tert-butyl-3-(6-methyl-2-pyridyl)-1H-1,2,4-triazole}complex

A new emissive mononuclear homoleptic Cu（Ⅰ） complex of 5-rert-butyl-3-（6-methyl-2-pyridyl）-1H-1,2,4-triazole（bmptzH）,[Cu（bmptzH）2]（ClO4）（1）,has been synthesized by treatment of[Cu（PPh_3）2（CH3CN）2]（ClO4） or [Cu（CH3CN）4]（ClO4） with the bmptzH ligand.It is revealed that complex 1 displays a distorted N4 tetrahedral arrangement formed by two bmptzH chelates,in which bmptzH adopts a neutral bidentate chelating coordination mode using the N atom of the pyridyl ring and the 4-N not 2-N atom of the 1,2,4-triazolyl ring.It is shown that complex 1 is highly stable and exhibits good luminescence properties in solution and solid states at room temperature due to the introduction of a methyl group at the ortho-position of the pyridyl ring.