Determination of Tramadol in Human Serum by Capillary Electrophoresis with the End-Column Electrochemiluminescence Detection

A capillary electrophoresis (CE) coupled with end-column electrochemiluminescence (ECL) detection method for the analysis of tramadol (TMD) has been investigated. ECL detection was working electrode biased at 1.2 V in a 20mmol·L-1 sodium phosphate buffer (pH = 8.0) containing 5 mmol·L-1 Ru (where bpy = 2,2’-bipyridyl). Linear correlation (r ≥ 0.997) between ECL intensity and drug concentration was obtained in the range 3 × 10-4 - 6 × 10-6 mol·L-1. The limits of detection (LODs) for tramadol in water was 3.012 × 10-8 mol·L-1(S/N = 3). The relative standard deviation values on peak size (10-5 mol·L-1 level) and migration time for the tramadol were 4.58% and 1.39% (n = 10), respectively. Applicability of the CE-ECL method to the analysis of human serum spiked with tramadol was

Biocatalytic Synthesis of Pyruvate from DL-lactate with Enzymes in Pseudomonas sp.

A novel method of preparing pyruvate from DL-lactate catalyzed by enzymes from a bacterial strain of Pseudomonas sp. SM-6 was proposed. Catalytic processes of cell-free extract enzymes and immobilized enzymes were evaluated. The kinetic data were studied, too.

Synthesis and Crystal Structure of a New Guanidinatoaluminium Complex and Its Utilityin the Meerwein-Ponndorf-Verley Reduction

The treatment of pyrrolidine （C4HsNI-I） with sequentially trimethylaluminum andcarbodiimide CyN--C=NCy in a molar ratio of 1 ：1：1 in the presence of O2 afforded a newguanidinatoaluminurn complex, [{（C4HsN）C（NCy）2}AIMe（/I-OMe）]2 （1）, which was characterizedby elemental analyses, 1H, 13C NMR spectra and single-crystal X-ray diffraction analysis. ComplexI crystallizes in monoclinic, space group P21/c with a = 9.8330（9）, b = 8.5786（8）, c = 24.159（2） A,β= 92.927（2）°, V= 2035.3（3） A3, Dc = 1.141 g cm^-3, F（000） = 768 and μ= 0.110 mm^-l. In addition,complex 1 was used to catalyze the Meerwein-Ponndorf-Verley （MPV） reduction and 1 as apre-catalyst at low catalyst loadings （5 tool%） exhibited good catalytic activity for the reduction ofa series of aldehydes to the corresponding alcohols in good yields （cony. up to 99%）.

Roles of constitutively secreted extracellular chaperones in neuronal cell repair and regeneration

Protein quality control involves many processes that jointly act to regulate the expression, localization, turnover, and degradation of proteins, and has been highlighted in recent studies as critical to the differentiation of stem cells during regeneration. The roles of constitutively secreted extracellular chaperones in neuronal injury and disease are poorly understood. Extracellular chaperones are multifunctional proteins expressed by many cell types, including those of the nervous system, known to facilitate protein quality control processes. These molecules exert pleiotropic effects and have been implicated as playing important protective roles in a variety of stress conditions, including tissue damage, infections, and local tissue inflammation. This article aims to provide a critical review of what is currently known about the functions of extracellular chaperones in neuronal repair and regeneration and highlight future directions for this important research area. We review what is known of four constitutively secreted extracellular chaperones directly implicated in processes of neuronal damage and repair, including transthyretin, clusterin, α2-macroglobulin, and neuroserpin, and propose that investigation into the effects of these and other extracellular chaperones on neuronal repair and regeneration has the potential to yield valuable new therapies.

Direct conversion of corn cob to formic and acetic acids over nano oxide catalysts

Considering energy shortage, large molecules in corn cob and easy separation of solid catalysts, nano oxides are used to transform corn cob into useful chemicals. Because of the microcrystals, nano oxides offer enough accessible sites for cellulose, hemicellulose and monosaccharide from corn cob hydrolysis and oxidant. Chemical conversion of corn cob to organic acids is investigated over nano ceria, alumina, titania and zirconia under various atmospheres. Liquid products are mainly formic and acetic acids. A small amount of other compounds, such as D-xylose,D-glucose, arabinose and xylitol are also detected simultaneously. The yield of organic acids reaches 25%–29% over the nano oxide of ceria,zirconia and alumina with 3 h reaction time under 453 K and 1.2 MPa O2. The unique and fast conversion of corn cob is directly approached over the nano oxides. The results are comparative to those of biofermentation and offer an alternative method in chemically catalytic conversion of corn cob to useful chemicals in a one-pot chemical process.

Preparation of kakkatin derivatives and their anti-tumor activity

BACKGROUND Modern pharmacological studies have confirmed that plant-derived compounds from Puerariae flos(PF)has significant biological activities against liver damage,tumors and inflammation.Kakkatin is an isoflavone polyphenolic compound isolated from PF flower.However,the effect of kakkatin and its derivatives on anti-tumor has not been well explored.AIM To design and synthesize a kakkatin derivative[6-(hept-6-yn-1-yloxy)-3-(4-hydroxyphenyl)-7-methoxy-4H-chromen-4-one(HK)]to explore its anti-tumor biological activity.METHODS Hept-6-yn-1-yl ethanesulfonate was introduced to replace hydrogen at the hydroxyl position of kakkatin phenol,and the derivative of kakkatin was prepared;the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to detect cell viability,a clone formation assay was adopted to detect cell proliferation,apoptosis,necrosis,and cell cycles were analyzed by Annexin V/propidium iodide staining and flow cytometry.Cell migration and invasion ability were evaluated by cell scratch assay and transwell assay.The potential mechanism of HK on hepatocellular carcinoma(HCC)SMMC-7721 cells was explored through network pharmacology and molecular docking,and finally real-time PCR assays was used to verify the potential targets and evaluate the biological activity of HK.RESULTS Compared with kakkatin,the modified HK did not significantly increase the inhibitory activity of gastric cancer MGC803 cells,but the inhibitory activity of HCC SMMC-7721 cells was increased by about 30 times,with an IC50 value of 2.5μM,and the tumor inhibition effect was better than cisplatin,which could significantly inhibit the cloning,invasion and metastasis of HCC SMMC-7721 cells,and induce apoptosis and G2/M cycle arrest.Its mechanism of action is mainly related to the upregulation of PDE3B and NFKB1 target proteins in the cAMP pathway.CONCLUSION HK have a significant inhibitory effect on HCC SMMC-7721 cells,and the targets of their action may be PDE3B and NFKB1 proteins in the cAMP pathway,making it a good lead drug for the treatment of HCC.

Flow Injection Chemiluminescence Determination of 4-methylsalicylic

As potassium bichromate can be reduced by 4-methysalicylic acid to chromium(III) which enhance the CL intensity of luminol-H2O2 system,a new chemiluminescence system for the determination of 4-methysalicylic acid has been established.The relative CL intensity was correlated with salicylic acid concentration in the range 7.0×10-9～8.0×10-6 mol/L,and the detection limit was 1.0×10-9 mol/L.The relative standard deviation(n=8) for 4.0×10-7 mol/L 4-methysalicylic acid is 2.9%.The method has been applied to the determination of 4-methysalicylic acid in the bactericidal solutions with satisfactory results.

Probing the Two-stage Transition upon Crossing the Glass Transition of Polystyrene by Solid-state NMR

A two-stage transition upon crossing the glass transition of polystyrene with increasing temperature was precisely determined and interpreted by using solid-state nuclear magnetic resonance （SSNMR）, 1H-XH dipolar couplings based double quantum-filtered （DQF） and dipolar filter （DF） experiments and 13C chemical shift anisotropy （CSA） based centerband-only detection of exchange （CODEX） experiment are used to fully characterize the time scale of molecular motions during the glass transition. While differential scanning calorimetry （DSC） and CODEX experiment predicted the first stage of glass transiton, DQF and DF experiments provided the evidence for the second stage transition during which the time scale of molecular motions changed from very slow （t 〉 ms） to very fast （t 〈 Its）. The first stage of glass transition begins with the occurrence of remarkable slow re-orientation motions of the polymer backbone segments and ends when the degree of slow motion reaches maximum. The onset and endpoint of the conventional calorimetric glass transition of polystyrene can be quantitatively determined at the molecular level by SSNMR. In the second stage, a subsequent dramatic transition associated with the melting of the glassy components was observed. In this stage liquid-like NMR signals appeared and rapidly increased in intensity after a characteristic temperature Tf （-1.1Tg）. The signals associated with the glassy components completely disappeared at another characteristic temperature Tc （-1.2Tg）.

Improved Efficiency Droop in a GaN-Based Light-Emitting Diode with an AlInN Electron-Blocking Layer

GaN-based light-emitting devices(LEDs)with different electron blocking layers are theoretically studied and compared by using the advanced physical models of a semiconductor device simulation program.It is found that the structure with an AlInN electron blocking layer shows improved light output power,lower current leakage and efficiency droop.Based on numerical simulation and analysis,these improvements of the electrical and optical characteristics are mainly accounted for by efficient electron blocking.It can be concluded that Auger recombination is responsible for the dominant origin of the efficiency droop of a GaN-based LED as current increases.

Interfacial Engineering of NiFeP/NiFe-LDH Heterojunction for Efficient Overall Water Splitting

In consideration of application prospect of non-noble metallic materials catalysts,the study of exploring more highly effective electrocatalysts has been focused on by researchers.Herein,a novel strategy is employed to construct a heterojunction consisting of metal phosphide Ni_(x)Fe_(y)P and layered double hydroxide(LDH)with graphene oxide(GO)as conductive support.By adjusting the molar ratio of Ni to Fe,a series of heterojunctions with mixed valence state Fe^(δ+)/Fe^(3+)and Ni^(δ+)/Ni^(2+)(δis likely close to 0)redox couples are achieved and strong synergistic effects towards overall water splitting performance are found.The optimized catalyst with a Ni/Fe molar ratio of 0.72:0.33,namely Ni_(0.7)Fe_(0.3)P/LDH/GO,delivers ultra-low overpotentials for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)of 79 and 198 mV at the current density of 10 mA·cm^(-2),respectively.Furthermore,for overall water-splitting practical application,it only requires 1.526 V at 10 mA·cm^(-2)with robust stability,which is superior to most reported electrocatalysts.Experimental results demonstrate the im-proved electronic conductivity,enlarged electrochemically active area and accelerated kinetics together account for the enhanced performance.This work supplies new prospects for the promotion and application of such heterojunction electrocatalysts in overall water splitting.

Sorption of inorganic nanoparticles in woven cellulose fabrics

Titanium dioxide was deposited from aqueous suspension onto cellulosic surfaces. Titania was sourced from Degussa （P25TM, 70：30 anatase：rutile）. Dry uptake of particles was shown to be rapid and dominant with one-third of the deposition occurring in less than 30 s and over one-half in the first minute. Isotherms were recorded to compare the rate of titanium deposition on dry and pre-wetted cotton. In the dry case uptake reached a maximum in 30 min whereas in the pre-wetted case the uptake was seen to continue beyond 180 min. A broad trend of higher deposition occurring at lower pH was seen, corresponding to the region where surface charges were opposite and thus attractive. Dry pickup was less significant at high pH. The response to varying ionic strength was complex and was attributed to the combined effect of charge screening, particle aggregation and consequent particle entrapment or occlusion. Titania deposition into the interstices of woven cotton sheets resulted in the formation of inorganic, nanoparticulate skeletons which could be isolated by controlled combustion of the cellulose and thus cotton was suggested to have potential for the templated synthesis of high surface area semiconductor materials.

Defect engineering for high-selection-performance of N_(2) activation over CeO_(2)(111) surface

Nitrogen reduction reactions(NRR) under room conditions remain the challenge for N_(2)activation on metal-based catalysis materials. Herein, the M-doped CeO_(2)(111)(M = Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) with oxygen vacancies, are systematically investigated by spin-polarized DFT + U calculations.We discuss briefly the situation of OVs on pure and reduced cerium, and we found that(1) doping TMs can promote the formation of oxygen defects, apart from Ti and V-dopant,(2) the O atoms are easier to escape connecting to M atoms than the ones of adjacent atoms connecting to the Ce(111), the value of OVs formation energies decrease as the TMs radius decrease. Also, our computational results show that Cr-doped, Mn-doped, Fe-doped, and Co-doped CeO_(2)(111) adsorbs N;strongly than the stoichiometric surface and other M-doped CeO_(2)surfaces with adsorption energies of-0.82,-1.02,-0.83 and-1.05 e V.Through COHP analysis, it is found that the predicted active sites have good catalytic performance.