固相反应法合成Pt/MoO_3及其电催化作用

采用固相合成的方法制得直接甲醇燃料电池催化甲醇氧化的Pt/MoO3.XRD分析、循环伏安测试表明,Pt/MoO3对甲醇的氧化具有较好的催化作用,氧化峰电位出现在0.63V(vs.SCE),峰电流密度可达78.1mA·cm-2.

Specific determination of As(V) by an acid phosphatase-polyphenol oxidase biosensor

An original amperometric biosensor based on the simultaneous entrapment of acid phosphatase (AcP) and polyphenol oxidase (PPO) into anionic clays (layered double hydroxides) was developed for the specific detection of As(V). The functioning principle of the bienzyme electrode consisted of the successive hydrolysis of phenyl phosphate into phenol by AcP, followed by the oxidation of phenol into o-quinone by PPO. The phenyl phosphate concentration was, thus, monitored by potentiostating the biosensor at -0.2 V vs Ag/AgCl to detect amperometrically the generated quinone. The detection of As(V) was based on its inhibitory effect on AcP activity toward the hydrolysis of phenyl phosphate into phenol. The As(V) can be specifically determined in pH 6.0 acetate buffer without any interferences of As(III) or phosphate, the detection limit being 2 nM or 0.15 ppb after an incubation step for 20 min.

Self-assembled monolayer of polyoxometalate on gold surfaces: Quartz crystal microbalance, electrochemistry, and in-situ scanning tunneling microscopy study

A new kind of inorganic self-assembled monolayer (SAM) was prepared by spontaneous adsorption of polyoxometalate anion, AsMo11VO404-, onto a gold surface from acidic aqueous solution. The adsorption process, structure, and electrochemical properties of the AsMo11VO404- SAM were investigated by quartz crystal microbalance (QCM), electrochemistry, and scanning tunneling microscopy (STM). The QCM data suggested that the self-assembling process could be described in terms of the Langmuir adsorption model, providing the value of the free energy of adsorption at -20 KJ mol(-1). The maximum surface coverage of the AsMo11VO404- SAM on gold surface was determined from the QCM data to be 1.7 x 10(-10) mol cm(-2), corresponding to a close-packed monolayer of AsMo11VO404- anion. The analysis of the voltammograms of the AsMo11VO404- SAM on gold electrode showed three pairs of reversible peaks with an equal surface coverage of 1.78 x 10(-10) mol cm(-2) for each of the peaks, and the value was agreed well with the QCM data. In-situ STM image demonstrated that the AsMo11VO404- SAM was very uniform and no aggregates or multilayer could be observed. Furthermore, the high-resolution STM images revealed that the AsMo11VO404- SAM on Au(lll) surface was composed of square unit cells with a lattice space of 10-11 Angstrom at +0.7 V (vs Ag\AgCl). The value was quite close to the diameter of AsMo11VO404- anion obtained from X-ray crystallographic study. The surface coverage of the AsMo11VO404- SAM on gold electrode estimated from the STM image was around 1.8 x 10(-10) mol cm(-2), which was consistent with the QCM and electrochemical results.

Polyimide structure-property relationships - I. Polyimide properties vs dianhydride configuration

X-ray crystal structures of 2,2',3,3'-and 3,3',4,4'-biphenyltetracarboxylic dianhydride (2,2',3,3'- and 3,3',4,4'-BPDA) were determined. The dianhydride isomers have different symmetry caused by difference in two anhydride group positions and the dihedral angles between the two phenyl rings are 62.9 degrees for 2,2',3,3',-BPDA and 0 degrees for 3,3',4,4'-BPDA respectively. The polyimides from 2,2',3,3'-BPDA exhibit enhanced solubility, higher thermal stability, and higher glass transition temperature (T-g) compared with those from 3,3',4,4'-BPDA.

FLOW-INJECTION ANALYSIS OF MYOGLOBIN AND HEMOGLOBIN AT TOLUIDINE BLUE CHEMICALLY MODIFIED ELECTRODE

Electrodeposition of the phenothiazine mediator titrant toluidine blue onto a glassy carbon substrate at an appropriate potential was used to construct a toluidine blue chemically modified electrode (CME) exhibiting electrocatalytic reduction for myoglobin and hemoglobin. The CME catalyzed the hemoprotein electroreduction at the reduction potential of the mediator molecule. When the CME as used as a detector for flow injection analysis at a constant applied potential of -0.30 V vs. a saturated calomel electrode, it gave detection limits of 20 and 50 ng (1.2 and 0.78 pmol) injected myoglobin and hemoglobin, respectively, with a dynamic linear concentration range over 2 orders of magnitude. After a brief equilibration period, the CME retained nearly 90% of its initial myoglobin response over 8 hours of continuous exposure to the flow-through system.

Cloning and expression of glucose regulated protein 78 (GRP78) in Fenneropenaeus chinensis

GRP78 (78 kDa glucose-regulated protein), also known as BiP (immunoglobulin heavy-chain-binding protein), is an essential regulator of endoplasmic reticulum (ER) homeostasis because of its multiple functions in protein folding, ER calcium binding, and controlling of the activation of transmembrane ER stress sensors. In this report, we cloned the full length cDNA of GRP78 (FcGRP78) from Chinese shrimp Fenneropenaeus chinensis. This cDNA revealed a 2,325 bp with 1,968 bp open reading frame encoding 655 amino acids. This is the first reported GRP78 gene in Crustacea. The deduced amino acid sequence of FcGRP78 shared high identity with previously reported insect GRP78s: 86, 87 and 85% identity with GRP78s of Drosophila melanogaster, Aedes aegypti and Bombyx mori, respectively. Northern blot analysis shows that FcGRP78 is ubiquitously expressed in tissues of shrimp. Heat shock at 35A degrees C significantly enhanced the expression of FcGRP78 at the first hour, reached the maximum at 4 h post heat shock, dropped after that and resumed to the normal level until 48 h of post recovery at 25A degrees C. Additionally, differential expression of FcGRP78 was detected in haemocytes, hepatopancreas and lymphoid organ when shrimp were challenged by white spot syndrome virus (WSSV). We inferred that FcGRP78 may play important roles in chaperoning, protein folding and immune function of shrimp.

中老年危机热线来电者的应激源与自杀危险性

Objective: Psychosocial crisis and psychiatric disorders are two stressors for suicide action. This study will explore the differences on demographic characteristics, severity of depression, and suicidality of middle-aged and elder crisis line callers under the influences of psychosocial crisis or psychiatric disorders or two simultaneously-mixed stressors, in order to develop effective intervention strategies for crisis line. Methods: Analysis data of 1,092 cases selected from national crisis line callers aged 45 and over who were assessed with “Suicide risk assessment” during the period from December, 2002 to December, 2008. The sample were divided into three groups of psychosocial crisis, mental health problems, and mixed-stressors of three types of general callers (48.2%, 32.3%, 19.5%), callers with current suicide ideation (43.7%, 33.0%, 23.3%) and callers attempted suicide 2 weeks prior to the call (33.6%, 42.3%, 24.1%) respectively according to the operators’ judgments of the callers’ claimed difficult situations and classification system of crisis line database. X2 test and Tukey-type and Multinomial Logistic Regression multiple comparison methods are applied to analysis the differences of the three groups. Results: In agreement with previous studies, more females (71.3%, X2=13.45, P<0.001), especially females influenced by relationship stressors (76.8%, X2=25.12, P<0.001) made the call for crisis. Among general callers, the check-out rates of Major Depression Episode of mixed-stressor callers (78.5%, P<0.001) and problem callers (68.7%, P<0.05) were significantly higher than that of crisis callers (57.1%). The check-out rates of suicide ideation of mixed-stressor callers (71.4%) were significantly higher than that in crisis callers (53.8%, P<0.001) and problem callers (60.9%, P<0.05). The check-out rates of prior suicide attempts of mixed-stressor (16.6%, P<0.05) and problem callers (18.5%, P<0.01) were significantly higher than that of crisis callers (9.8%). More than half of the mixed-stressor callers (51.8%) reported over 50% degree of hopelessness, which was significantly higher than that of crisis callers (35.6%, P<0.01) and problem callers (38.2%, P<0.05). Fewer crisis callers sought medical help than problem and mixed-stressor callers among three types of callers (X2=241.35, 146.56, 50.87; P<0.001). Compare to non-compound crisis callers, the proportion of minor, severe depression and prior depression diagnosis (14.0% vs. 17.4%; 54.9% vs. 65.2%; 0 vs. 2.2%; X2=14.35，P<0.01), suicide ideation (51.1% vs. 64.0%, P<0.05) and prior suicide attempts (8.4% vs. 15.0%, P<0.05) in compound crisis callers were significantly higher. There were more compound crisis callers with over 50% hopelessness (51.9% vs. 31.0%，X2=11.96，P<0.01). Conclusion: As predicted, among middle-aged and elderly participants, mixed-stressor and compound crisis callers were higher in degree of severity of depression and suicidality. Intervention strategies should be developed addressing to specific stressor or stressors. The promotions of crisis callers’ medical help seeking behavior need to be emphasized.

Otimização do método de Elisa indireto não competitivo para detecção e quantificação de aflatoxina B1 em cereais.

2007

Measurements of the heat capacity of an azeotropic mixture of water and n-butanol from 78 to 320 K

Molar heat capacities of n-butanol and the azeotropic mixture in the binary system [water (x=0.716) plus n-butanol (x=0.284)] were measured with an adiabatic calorimeter in a temperature range from 78 to 320 K. The functions of the heat capacity with respect to thermodynamic temperature were established for the azeotropic mixture. A glass transition was observed at (111.9 +/- 1.1) K. The phase transitions took place at (179.26 +/- 0.77) and (269.69 +/- 0.14) K corresponding to the solid-liquid phase transitions of. n-butanol and water, respectively. The phase-transition enthalpy and entropy of water were calculated. A thermodynamic function of excess molar heat capacity with respect to temperature was established, which took account of physical mixing, destructions of self-association and cross-association for n-butanol and water, respectively. The thermodynamic functions and the excess thermodynamic ones of the binary systems relative to 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity and the calculated excess heat capacity with respect to temperature.