Synergistic use of thermogravimetric and electrochemical techniques for thermodynamic study of TiOx (1.67 <= x <= 2.0) at 1573 K

A thermodynamic study of the Ti-O system at 1573 K has been conducted using a combination of thermogravimetric and emf techniques. The results indicate that the variation of oxygen potential with the nonstoichiometric parameter delta in stability domain of TiO2-delta with rutile structure can be represented by the relation, Delta mu o(2) = -6RT In delta - 711970(+/-1600) J/mol. The corresponding relation between non-stoichiometric parameter delta and partial pressure of oxygen across the whole stability range of TiO2-delta at 1573 K is delta proportional to P-O2(-1/6). It is therefore evident that the oxygen deficient behavior of nonstoichiometric TiO2-delta is dominated by the presence of doubly charged oxygen vacancies and free electrons. The high-precision measurements enabled the resolution of oxygen potential steps corresponding to the different Magneli phases (Ti-n O2n-1) up to n = 15. Beyond this value of n, the oxygen potential steps were too small to be resolved. Based on composition of the Magneli phase in equilibrium with TiO2-delta, the maximum value of n is estimated to be 28. The chemical potential of titanium was derived as a function of composition using the Gibbs-Duhem relation. Gibbs energies of formation of the Magneli phases were derived from the chemical potentials of oxygen and titanium. The values of -2441.8(+/-5.8) kJ/mol for Ti4O7 and -1775.4(+/-4.3) kJ/mol for Ti3O5 Obtained in this study refine values of -2436.2(+/-26.1) kJ/mol and-1771.3(+/-6.9) kJ/mol, respectively, given in the JANAF thermochemical tables.

Magnetic properties of rare earth nickelates of the Ln(2)BaNiO(5) family

Rare-earth nickelates Ln(2)BaNi(1-x)Cu(2)O(5), Ln = Nd and Dy, and Dy2-xYxBaNiO5 have been synthesized in order to investigate the effect of substitution of Ni by Cu and Dy by nonmagnetic Y on the magnetic properties of the nickelates. In Ln(2)BaNi(1-x)Cu(x)O(5), the nickelate structure (x=0.0) changes to the cuprate structure (x=1.0) at a specific composition (x=0.3). The Neel temperature of Nd2BaNi1-xCuxO5 decreases continuously with increase in x upto x=0.3 (T-N = 18K); when x > 0.3, the materials are paramagnetic down to 20K. The mu(eff) in Nd2BaNi1-xCxO5 essentially corresponds to the contribution of the Nd ions. In Dy2-xYxBaNiO5, the Neel temperature decreases from 40K when x=0.0 to 24K when x=1.5. The compositions with 1.5 less than or equal to x less than or equal to 2 (including the x=1.95 composition) are paramagnetic down to 20K, unlike Y2BaNiO5 (x=2.0) which exhibits a T-N of 370K. Even the smallest concentration of paramagnetic Dy seems to destroy the antiferromagnetic Ni-O-Ni chains in Y2BaNiO5.

Synthesis based on cyclohexadienes. Part-27. Synthesis of functionalized tricyclo[5.2.2.0(1,5)]undecanes

A new methodology for the construction of tricyclo[5.2.2.0(1,5)]undecanes is described from indane-4-carboxylic acids. Birch reduction of indane-4-carboxylic acids followed by conjugation and cycloaddition with alpha-chloroacrylonitrile and hydrolysis lead to the tricyclic compounds 36 and 48 which are intermediates in the eremolactone synthesis.

Tensile flow behaviour of 2.25Cr-1Mo ferritic steel base metal and simulated heat affected zone structures of 2.25Cr-1Mo weld joint

Tensile tests in the temperature range 298 to 873 K have been performed on 2.25Cr-1Mo base metal and simulated heat affected zone (HAZ) structures of its weld joint, namely coarse grain bainite, fine grain bainite and intercritical structure. Tensile flow behaviour of all the microstructural conditions could be adequately described by the Hollomon equation (sigma = K-1 epsilon(n1)) at higher (> 623 K) temperatures. Deviation from the Hollomon equation was observed at low strains and lower (< 623 K) temperatures. The Ludwigson modification of Hollomon's equation, sigma = K-1 epsilon(n1) + exp (K-2 + n(2) epsilon), was found to describe the flow curve. In general, the flow parameters n(1), K-1, n(2) and K-2 were found to decrease with increase in temperature except in the intermediate temperature range (423 to 623 K). Peaks/plateaus were observed in their variation with temperature in the intermediate temperature range coinciding with the occurrence of serrated flow in the load-elongation curve. The n(1) Value increased and the K-1 value decreased with the type of microstructure in the order: coarse grain bainite, fine grain bainite, base metal and intercritical structure. The variation of nl with microstructure has been rationalized on the basis of mean free path (MFP) of dislocations which is directly related to the inter-particle spacing. Larger MFP of dislocations lead to higher strain hardening exponents n(1).

A short, formal synthesis of (+/-)-2-pupukeanone

A short approach to (+/-)-2-pupukeanone, starting from 2,6-dimethylcyclohexenone employing a combination of Michael-Michael reaction and an intramolecular rhodium carbenoid C-H insertion as key reactions, is described.

Expression and function of cyclooxygenase-2 is necessary for hamster blastocyst hatching

Blastocyst hatching is critical for successful implantation leading to pregnancy. Its failure causes infertility. The phenomenon of blastocyst hatching in humans is poorly understood and the available information on this stems from studies of rodents such as mice and hamsters. We and others showed that hamster blastocyst hatching is characterized by firstly blastocyst deflation followed by a dissolution of the zona pellucida (zona) and accompanied by trophectodermal projections (TEPs). We also showed that embryo-derived cathepsins (Cat) proteases, specifically Cat-L, -B and -P act as zonalysins and are responsible for hatching. In this study, we show the expression and function of one of the potential regulators of embryogenesis, cyclooxygenase (COX)-2 during blastocyst development and hatching. The expression of COX-2 mRNA and protein was observed in 8-cell through hatched blastocyst stages and it was also localized to blastocysts TEPs. Specific COX-2 inhibitors, NS-398 and CAY-10404, inhibited blastocyst hatching; percentages achieved were only 28.4 5.3 and 32.3 5.4, respectively, compared with 90 with untreated embryos. Interestingly, inhibitor-treated blastocysts failed to deflate, normally observed during hatching. Supplementation of prostaglandins (PGs)-E-2 or -I-2 to cultured embryos reversed the inhibitors effect on hatching and also the deflation behavior. Importantly, the levels of mRNA and protein of Cat-L, -B and -P showed a significant reduction in the inhibitor-treated embryos compared with untreated embryos, although its mechanism remains to be examined. These data provide the first evidence that COX-2 is critical for blastocyst hatching in the golden hamster.

2-(Phenylazo)pyridineplatinum(II) Catecholates Showing Photocytotoxicity, Nuclear Uptake, and Glutathione-Triggered Ligand Release

Platinum(II) complexes Pt(pap)(an-cat)] (1) and Pt(pap)(py-cat)] (2) with 2-(phenylazo)pyridine (pap), 4-2-(anthracen-9-ylmethylene)amino]ethyl]benzene-1,2-diol (H(2)an-cat), and 4-2-(pyren-1-ylmethylene)amino]ethyl]benzene-1,2-diol (H2py-cat) were prepared, and their photoinduced cytotoxicity was studied. The complexes were found to release catecholate ligand in the presence of excess glutathione (GSH), resulting in cellular toxicity in the cancer cells. The catecholate complex Pt(pap)(cat)] (3) was prepared and used as a control. Complex 3, which is structurally characterized by X-ray crystallography, has platinum(II) in a distorted square-planar geometry. The complexes are redox-active, showing responses near 0.6 and 1.0 V versus SCE in N,N-dimethylformamide/0.1 M tetrabutylammonium perchlorate corresponding to a two-step catechol oxidation process and at -0.3 and -1.3 V for reduction of the pap ligand. Complex 1 showed remarkable light-induced cytotoxicity in HaCaT (human skin keratinocytes) and MCF-7 (human breast cancer) cells, giving IC50 value of similar to 5 mu M in visible light of 400-700 nm and >40 mu M in the dark. The 2',7'-dichlorofluorescein diacetate (DCFDA) assay showed the generation of reactive oxygen species (ROS), which seems to trigger apoptosis, as is evident from the annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) assay. The fluorescence microscopic images showed significant nuclear localization of the complexes and free ligands. A mechanistic study revealed possible reduction of the coordinated azo bond of pap by cellular GSH, releasing the catecholate ligand and resulting in remarkable photochemotherapeutic action of the complexes.

Isolation of the murine interleukin 2 gene and characterization of its regulatory architecture

Interleukin 2 (IL2) is the primary growth hormone used by mature T cells and this lymphokine plays an important role in the magnification of cell-mediated immune responses. Under normal circumstances its expression is limited to antigen-activated type 1 helper T cells (T_H1) and the ability to transcribe this gene is often regarded as evidence for commitment to this developmental lineage. There is, however, abundant evidence than many non-T_H1 T cells, under appropriate conditions, possess the ability to express this gene. Of paramount interest in the study of T-cell development is the mechanisms by which differentiating thymocytes are endowed with particular combinations of cell surface proteins and response repertoires. For example, why do most helper T cells express the CD4 differentiation antigen?

As a first step in understanding these developmental processes the gene encoding IL2 was isolated from a mouse genomic library by probing with a conspecific IL2 cDNA. The sequence of the 5' flanking region from + 1 to -2800 was determined and compared to the previously reported human sequence. Extensive identity exists between +1 and -580 (86%) and sites previously shown to be crucial for the proper expression of the human gene are well conserved in both sequence location in the mouse counterpart.

Transient expression assays were used to evaluate the contribution of various genomic sequences to high-level gene expression mediated by a cloned IL2 promoter fragment. Differing lengths of 5' flanking DNA, all terminating in the 5' untranslated region, were linked to a reporter gene, bacterial chloramphenicol acetyltransferase (CAT) and enzyme activity was measured after introduction into IL2-producing cell lines. No CAT was ever detected without stimulation of the recipient cells. A cloned promoter fragment containing only 321 bp of upstream DNA was expressed well in both Jurkat and EL4.El cells. Addition of intragenic or downstream DNA to these 5' IL2-CAT constructs showed that no obvious regulatory regions resided there. However, increasing the extent of 5' DNA from -321 to -2800 revealed several positive and negative regulatory elements. One negative region that was well characterized resided between -750 and -1000 and consisted almost exclusively of alternating purine and pyrimidines. There is no sequence resembling this in the human gene now, but there is evidence that there may have once been.

No region, when deleted, could relax either the stringent induction-dependence on cell-type specificity displayed by this promoter. Reagents that modulated endogenous IL2 expression, such as cAMP, cyclosporin A, and IL1, affected expression of the 5' IL2-CAT constructs also. For a given reagent, expression from all expressible constructs was suppressed or enhanced to the same extent. This suggests that these modulators affect IL2 expression through perturbation of a central inductive signal rather than by summation of the effects of discrete, independently regulated, negative and positive transcription factors.

Length-weight relationship in freshwater cat fish Clarias batrachus (Linn.)

Clarias batrachus (Linn.), a common freshwater cat fish of Bhima River, has high economic value and considerable fishery importance. The length-weight relationship in the logarithmic way for this fish can be written as: Log W = 4.503717819 + 2.70681765 Log L. This is close to the cubic law indicating the isometric growth of the fish in its natural habitat. The correlation coefficient (r) was found to be 0.9824 which showed a good relationship between the two parameters.

Distribution pattern of some biochemical constituents in muscle of the common cat fish, Heteropneustes fossilis (Bloch)

The quantitative distribution pattern of fat, moisture, protein and ash has been studied in the muscle of the various zones corresponding to the dorsal and ventral regions of the body of a common cat fish, H. fossilis (Bloch). The ventral part of the body showed more accumulation of fat and ash than the dorsal part, while this dorso-ventral gradation was not marked in the case of protein content. All the four constituents also showed an increase from the anterior to the posterior zones, both in the ventral as well as dorsal regions of the body. The distribution of moisture followed an almost opposite pattern, indicating an inverse relationship with fat and ash contents.

Fat and water distribution patterns in the flesh of the common cat-fish Wallago attu (Bl. & Schn.)

The quantitative distributional pattern of fat and water has been studied in the flesh of the various zones corresponding to the dorsal and ventral regions of the body of a common cat-fish, Wallago attu. The ventral aspect of the body showed more accumulation of fat than the dorsal aspect. The fat content in the ventral region also exhibited an increase from the anterior to the posterior zones. In the dorsal region, however, the back portion of the body, behind the dorsal fin, generally possessed low fat content. On an average, the highest fat accumulation was observed in the caudal peduncle region. The distribution of water followed an almost opposite pattern of distribution, indicating an inverse relationship with fat.

Seasonal variations in the total cholesterol content of the liver of cat fish Heteropnuestes fossilis (Bloch)

Variations in the total liver cholesterol content of Heteropnuestes fossilis followed well defined seasonal cycle. A decline was recorded during the period when the gonads were passing through the peak ripe stage. The highest value of the cholesterol was however attained before this phase of gonad maturation. Concentration pattern of liver cholesterol seemed related to variations in the cholesterol metabolism of the fish, necessitated, besides other factors, by the demand for sex hormones. A possibility of the influence of feeding intensity on liver cholesterol content has also been indicated.

Cat fish egg pickle

Cat fish constitutes one of the important fisheries in India. Attempts were made for the better utilization of eggs. This paper describes trials made a favourable product such as pickle.

Microcystin-RR-induced accumulation of reactive oxygen species and alteration of antioxidant systems in tobacco BY-2 cells

Microcystins are cyclic heptapeptide hepatoxins produced by cyanobacteria. It has been shown that microcystins have adverse effects on animals and on plants as well. Previous researches also indicated that microcystins were capable of inducing oxidative damage in animals both in vivo and in vitro. In this study, tobacco BY-2 suspension cell line was applied to examine the effects of microcystin-RR on plant cells. Cell viability and five biochemical parameters including reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione peroxide (GPX) and peroxide dismutase (POD) were investigated when cells were exposed to 50 mg/L microcystin-RR. Results showed that microcystin-RR evoked decline of the cell viability to approximately 80% after treating for 144 h. ROS levels, POD and GPX activities of the treated cells were gradually increased with a time dependent manner. Changes of SOD and CAT activities were also detected in BY-2 cells. After 168 h recovery, ROS contents, POD, GPX and CAT activities returned to normal levels. These results suggest that the microcystin-RR can cause the increase of ROS contents in plant cells and these changes led to oxidant stress, at the same time, the plant cells would improve their antioxidant abilities to combat mirocystin-RR induced oxidative injury. (c) 2005 Elsevier Ltd. All rights reserved.

1. 稀土催化体系异戊二烯本体聚合动力学 2. 不同催化剂对聚异戊二烯甲苯溶液的作用

本文回顾和评述了Ziegler-Natra催化双烯定向聚合的发展，现状及展望，特别是较为详细地讨论了稀土体系的聚合催化剂，聚合机理，聚合动力学以及双烯本体聚合的有关问题。本工作的第一部分内容研究了异戊二烯在Nd(naph)_3 + Al(i-Bu)_3 + Al_2Et_3Cl_3催化体系作用下的本体聚合热效应及本休聚合动力学。指出任本实验条件，温度在-10 ℃ - +5 ℃范围内，聚合体系内温度和聚合环境温度基本一致。在此实验条件下，聚合过程可分为三阶段：聚合初期，聚合活性中心数目尚未稳定，聚合速率逐渐增大，为非稳态聚合阶段；聚合中期，聚合速率恒定，聚合呈稳态特征；聚合后期，聚合为扩散控制阶段。并得到稳太聚合阶段的聚合动力学方程 R_p = k_p[Cat]~(1.96)M. 其聚合反应表观活化能为16.7 kcal/mol。同时考究了聚合物特性粘数和分子量随聚合转化率，聚合催化剂用量，聚合温度等等变化民政部实验结果表明，该催化体系异戊二烯本体聚合仍具有活性聚合的某些特征。本工作的第二部分根据不同催化剂对聚异戊二烯甲苯溶液的作用结果，解释了TiCl_4 + Al(i-Bu)_3催化体系异戊二烯本体聚合转化率很低。聚合产物的凝胶含量较高，而NCl(naph)_3 + Al(i-Bu)_3 + Al_2Et_3Cl_3催化体系异戊二烯本体聚合转化率很容易达到80%。 聚合产物基本不含凝胶的实验事实。实验结果表明，将Ti催化剂加入异戊胶液中，有凝胶生成，且凝胶生成量随催化剂用量的增大而增大。而Nd催化剂不能使异戊胶液生成凝胶。这证实了在异戊二烯本体聚合和溶液聚合中，由于Ti催化剂的阳离子活性，可使线性聚异戊二烯中的不饱合双键发生阳离子反应，生成聚集体结构，星形结构、三维网状结构等三种可能结构的凝胶大分子。从而说明因生成结构紧密的凝胶分子将聚合活性中心紧紧地包围在其中，单体向活性能心扩散困难，致使Ti体系异戊二烯聚合转化率很难提高。根据红外及核磁谱图，Ti或Nd催化剂的加入均未改变聚合物的微观结构，更无环化结构生成。认为聚合物在两催化剂作用下，特性粘数的降低是由于聚合物链存在的不稳定位置及不饱合双键在催化剂的作用下发生了断链或断链后进一步支化所引起的。