The crystal structure and superconducting properties of monatomic bromine

The crystal structure and superconducting properties of monatomic bromine under high pressure have been studied by first-principles calculations. We have found the following phase transition sequence with increasing pressure: from body-centered orthorhombic (bco, phase II) to body-centered tetragonal structure (bct, phase III) at 126 GPa, then to face-centered cubic structure (fcc, phase IV) at 157 GPa, which is stable at least up to 300 GPa. The calculated superconducting critical temperature T(c) = 1.46 K at 100 GPa is consistent with the experimental value of 1.5 K. In addition, our results of T(c) decrease with increasing pressure in all the monatomic phases of bromine, similar to monatomic iodine. Further calculations show that the decrease of λ with pressure in phase IV is mainly attributed to the weakening of the 'soft' vibrational mode caused by pressure.

Diversity and spatial distribution of amoA-encoding archaea in the deep-sea sediments of the tropical West Pacific Continental Margin

AIMS

The ecological characteristics of the deep-sea amoA-encoding archaea (AEA) are largely unsolved. Our aim was to study the diversity, structure and distribution of the AEA community in the sediments of the tropical West Pacific Continental Margin, to develop a general view of the AEA biogeography in the deep-sea extreme environment.

METHODS AND RESULTS

Archaeal amoA clone libraries were constructed. Diverse and novel amoA sequences were identified, with the Bohol Sea, Bashi Strait and Sibuyan Sea harbouring the highest and the Bicol Shelf the lowest AEA diversity. Phylogenetic and statistical analyses illustrate a heterogeneous distribution of the AEA community, probably caused by the differential distribution of the terrestrial or estuarine AEA in the various sampling sites.

CONCLUSIONS

The deep-sea sedimentary environments potentially harbour diverse and novel AEA in the tropical West Pacific Continental Margin. The stations in the Philippine inland seas (including station 3043) may represent AEA assemblages with various terrestrial influences and the stations connected directly to the open Philippine Sea may represent marine environment-dominant AEA assemblages.

SIGNIFICANCE AND IMPACT OF STUDY

Our study indicates the potential importance of geological and climatic events in the transport of terrestrial micro-organisms to the deep-sea sedimentary environments, almost totally neglected previously.

Awareness of breast cancer among women in an urban region of China

Abstract #2104

Introduction: Even though breast cancer can be cured if detected early and treated appropriately, it remains the most common cause of cancer mortality for women living in some major cities in China. Moreover, the incidence of this disease has increased steadily in China over the last two decades. The aim of this cross-sectional study was to investigate the knowledge about breast cancer concerning risk factors, signs and symptoms, effective screening methods, treatment choices and prognosis among native Chinese women.
 Method: Two hundred and seventy healthy women were invited to complete a self-administered questionnaire in Taiyuan city of China. Participants' characteristics, including age, education, occupation, and awareness of breast cancer diagnosis, treatment and prognosis were collected and analyzed.
 Results: Two hundred and thirty nine women had returned the questionnaire. The response rate was 88.5%. The median age of women in this study was 44 years old (range: 25 – 72). Among them, more than one third had received tertiary education, 6.7% had breast cancer family history, and one quarter ever had benign breast disease. Most of the participants (60.3%) did not know how to perform breast self-examination (BSE), whereas 61.5% never did BSE. Only 2.9% of those who had performed BSE did so regularly. As for effective screening methods, more than half of the participants chose clinical breast examination (CBE), and 21.8% regarded mammography as a reliable mean. Most of women considered breast cancer a curable disease and assumed that therapeutic approaches should include surgery, chemotherapy, endocrine therapy, radiotherapy, and in some cases, traditional Chinese medicine. Only 8.8% of the participants identified two or more of the eight breast cancer risk factors. The factors mostly identified included breast cancer family history (33.5%), late birth (10%), and early age at menarche (9.6%). The breast cancer signs and symptoms mostly indicated were breast lump (54.4%), breast pain (26.4%), and nipple discharge (23.9%). Women who received high level education appeared to be more likely to perform BSE and possessed more knowledge regarding to breast cancer risk factors and treatment.
 Conclusion: The study indicates that awareness of breast cancer among Chinese women needs to be improved, and that breast cancer early-detection measures needs to be enhanced in China.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2104.

In silico quantitative prediction of peptides binding affinity to human MHC molecule: an intuitive quantitative structure-activity relationship approach

In this paper, we have handpicked 23 kinds of electronic properties, 37 kinds of steric properties, 54 kinds of hydrophobic properties and 5 kinds of hydrogen bond properties from thousands of amino acid structural and property parameters. Principal component analysis (PCA) was applied on these parameters and thus ten score vectors involving significant nonbonding properties of 20 coded amino acids were yielded, called the divided physicochemical property scores (DPPS) of amino acids. The DPPS descriptor was then used to characterize the structures of 152 HLA-A*0201-restricted CTL epitopes, and significant variables being responsible for the binding affinities were selected by genetic algorithm, and a quantitative structure-activity relationship (QSAR) model by partial least square was established to predict the peptide-HLA-A*0201 molecule interactions. Statistical analysis on the resulted DPPS-based QSAR models were consistent well with experimental exhibits and molecular graphics display. Diversified properties of the different residues in binding peptides may contribute remarkable effect to the interactions between the HLA-A*0201 molecule and its peptide ligands. Particularly, hydrophobicity and hydrogen bond of anchor residues of peptides may have a significant contribution to the interactions. The results showed that DPPS can well represent the structural characteristics of the antigenic peptides and is a promising approach to predict the affinities of peptide binding to HLA-A*0201 in a efficient and intuitive way. We expect that this physical-principle based method can be applied to other protein-peptide interactions as well.

Molecular graph fingerprint: a new molecular structural characterization method for the modelling and prediction of chromatographic retention behaviour of several persistent organic pollutants

How to extract and characterize information on molecular microstructures is deemed to be the key task to accurately simulate and predict molecular properties. In terms of atomic attributes, atoms in a molecule are divided into three levels. Based upon that, inter-atomic correlations are mapped to certain reasonable spatial coordinates in virtue of radial distribution function, generating the novel molecular graph fingerprint (MoGF), which essentially provides insight into molecular inner structures. MoGF, committing itself to transformation of molecular structures into characteristic graph curves, shows valuable advantages such as easy calculation, experimental parameters-free, rich information content, and structural significance and intuitive expressions. QSRR studies were performed for 115 polychlorinated dibenzofurans (PCDFs), 41 polychlorinated dibenzo-p-dioxins (PCDDs), 62 polychlorinated naphthalenes (PCNs), and 210 polychlorinated biphenyls (PCBs including the biphenyl)) tested for their retention behaviours on gas chromatographic column DB-5. The resulting PLS models showed good performances with correlation coefficients for both training and test sets above 0.97.

Magnetic field assisting DC electrodeposition: general methods for high-performance Ni nanowire array fabrication

One-dimensional magnetic nanowires are generally thought to show fine axial magnetism for their special high aspect ratio of the shape. However, the magnetic nanowire arrays fabricated by DC electrodeposition in template pores always show a low squareness in parallel to the nanowire direction. We developed two general and simple methods to improve the squareness of the as-fabricated Ni nanowire arrays parallel to the nanowire direction. The nanowires are found to be polycrystalline. The magnetism of the nanowire is also analyzed based on the microstructure.

Myo-inositol-1-phosphate (MIP) synthase inhibition: in-vivo study in rats

Lithium and valproate are the prototypic mood stabilizers and have diverse structures and targets. Both drugs influence inositol metabolism. Lithium inhibits IMPase and valproate inhibits MIP synthase. This study shows that MIP synthase inhibition does not replicate or augment the effects of lithium in the inositol sensitive pilocarpine-induced seizures model. This lack of effects may stem from the low contribution of de-novo synthesis to cellular inositol supply or to the inhibition of the de-novo synthesis by lithium itself.

Domain-domain motions in proteins from time-modulated pseudocontact shifts

In recent years paramagnetic NMR derived structural constraints have become increasingly popular for the study of biomolecules. Some of these are based on the distance and angular dependences of pseudo contact shifts (PCSs). When modulated by internal motions PCSs also become sensitive reporters on molecular dynamics. We present here an investigation of the domain-domain motion in a two domain protein (PA0128) through time-modulation of PCSs. PA0128 is a protein of unknown function from Pseudomonas aeruginosa (PA) and contains a Zn(2+) binding site in the N-terminal domain. When substituted with Co(2+) in the binding site, several resonances from the C-terminal domain showed severe line broadening along the (15)N dimension. Relaxation compensated CPMG experiments revealed that the dramatic increase in the (15)N linewidth came from contributions of chemical exchange. Since several sites with perturbed relaxation are localized to a single beta-strand region, and since extracted timescales of motion for the perturbed sites are identical, and since the magnitude of the chemical exchange contributions is consistent with PCSs, the observed rate enhancements are interpreted as the result of concerted domain motion on the timescale of a few milliseconds. Given the predictability of PCS differences and the easy interpretation of the experimental results, we suggest that these effects might be useful in the study of molecular processes occurring on the millisecond to microsecond timescale.

Influence of sample characteristics on quantification of carbamazepine hydrate formation by X-ray powder diffraction and Raman spectroscopy

This study aimed to assess the suitability of two widely utilized solid state characterization techniques namely powder X-ray diffraction (XRPD) and Raman spectroscopy, in polymorph detection and quantification for carbamazepine anhydrate and dihydrate mixtures. The influences of particle size, particle morphology, mixing, and in particular, surface bias on quantitation were investigated. Binary mixtures of carbamazepine anhydrate (form III) and dihydrate were prepared and analyzed using both XRPD and Raman spectroscopy in combination with partial least squares analysis. It was found that in principle both XRPD and Raman spectroscopy could be used to build calibration models for quantitative analysis, and a satisfactory correlation between the two techniques could be achieved. However, Raman spectroscopy appeared to be a more reliable quantification method because problems such as different particle size, morphology, and special distribution of the two solid state forms of the drug seemed to have no significant influence on Raman scattering in this study. The robust nature of Raman analysis greatly facilitates the whole quantification process from the preparation of calibration models to the quantification of in situ CBZ-DH conversion.

Visualizing the conversion of carbamazepine in aqueous suspension with and without the presence of excipients: A single crystal study using SEM and Raman microscopy

Visual observations of the hydration process of single carbamazepine (CBZ) crystals in water and in various excipient solutions [(1% w/v) - hydroxypropyl cellulose (HPC), poly(vinyl pyrrolidone) (PVP), sodium carboxymethylcellulose (CMC) at pH 7.5 and 3.0, and polyethylene glycol (PEG)] using scanning electron microscopy (SEM) are reported in this paper. Raman microscopy was used to confirm the chemical structures of the unconverted CBZ and the CBZ dihydrate (DH) needles. It was found that defect structures were a more important driving force than the nature of crystal faces for the initiation of the hydration, but face differences became obvious after 6 h immersion. The biggest crystal face grown from methanol, (100), was the slowest one to be covered with DH needles. A comparison of the molecular arrangements along the three crystal faces [(100), (010) and (001)] was carried out using crystal structure visualization software, and fewer polar groups exposed on the (100) face than on the (001) and (010) faces were found, explaining the comparatively weak interaction of the (100) face with water during hydration. Furthermore, investigation of the influence of excipients on the hydration of CBZ showed that both HPC and PVP strongly inhibited conversion, and no conversion of CBZ to DH was found after 18 h immersion in water. PEG and CMC (pH 7.5) were less potent inhibitors than HPC and PVP, and DH needles were observed on all the faces except the (100) face after 18 h immersion. No conversion was detected for the crystal immersed in CMC solution at pH 3.0. This is likely to be caused by the decreased polarity of CMC in water at pH 3.0 (pKa,cmc = 4.3), and thus a higher surface adsorption of CMC to the CBZ crystals in dispersion. The influence of excipients on the conversion of CBZ observed in this study agreed well with our previous quantitative studies using Raman spectroscopy. In this study, visual observation using electron microscopy has been demonstrated to be a unique and powerful tool to improve our understanding of polymorphic conversions of CBZ in aqueous suspension.