Beating the miscibility barrier between iron group elements and magnesium by high-pressure alloying

Iron and magnesium are almost immiscible at ambient pressure. The low solubility of Mg in Fe is due to a very large size mismatch between the alloy components. However, the compressibility of Mg is much higher than that of Fe, and therefore the difference in atomic sizes between elements decreases dramatically with pressure. Based on the predictions of ab initio calculations, we demonstrate in a series of experiments in a multianvil apparatus and in electrically and laser-heated diamond anvil cells that high pressure promotes solubility of magnesium in iron. At the megabar pressure range, more than 10 at. % of Mg can dissolve in Fe and then the alloy can be quenched to ambient conditions. A generality of the concept of high-pressure alloying between immiscible elements is demonstrated by its application to two other Fe group elements, Co and Ni.

Identification of temporal pattern of mandibular condylar growth: a molecular and biochemical experiment

OBJECTIVES

Based on the phenomenon that expression of type X collagen and capillary endothelium correlates with endochondral ossification, the prime aim of this study was to establish the temporal pattern of condylar growth in Sprague-Dawley rats by biochemically identifying the expression of these two factors.

DESIGN

Sprague-Dawley rats were divided into five groups representing five different stages during somatic pubertal growth. In situ hybridization and immunoperoxidase were performed to examine expression of type X collagen in hypertrophic zone and capillary endothelium in erosive zone of condylar cartilage. Computer-assisted imaging analyses were conducted to allow for a quantitative assessment of the expression of these two factors, from which the temporal pattern of condylar growth was inferred.

RESULTS

(1) Synthesis of type X collagen and emergence of capillary endothelium were critical factors during the transition of condylar cartilage from chondrogenesis into osteogenesis, a biological pathway that leads to endochondral bone formation, the mode through which the condyle grows. (2) Quantitative analyses revealed the temporal pattern of the expression of these two factors, indicating that the thrust of natural growth of the condyle in the rats occurred in concomitance with somatic pubertal growth, featured by an acceleration starting from day 38, a maximum growth rate on day 56, followed by a decrease afterwards.

CONCLUSION

It is suggested that the biochemical examination of growth markers, such as type X collagen, might be a new approach to accurately depict temporal pattern of condylar growth which is too delicate to be reflected by gross measurement not only in Sprague-Dawley rats but potentially also in other species.

Skeletal effects of bite jumping therapy on the mandible - removable vs. fixed functional appliances

AUTHORS: Shen G, Hagg U, Darendeliler MA.

OBJECTIVE

Based on an extensive review of the literature, the aim of this study was to explore the mainstream consensus on the controversial topic of whether the bite jumping treatment could enhance mandibular growth.

DESIGN

The data for removable and fixed functional appliances were respectively comprehended and analyzed with regard to their attributes in mandibular growth modification. Furthermore, numerous reported findings were assessed by relating them to some important factors influencing the effects of bite jumping, such as treatment timing, treatment duration and post-treatment follow-up, to allow for a more objective and accurate evaluation.

RESULTS

The key differences between removable and fixed appliances are working hours (intermittent vs. continuous), length of treatment time (long vs. short), optimal treatment timing (before puberty growth vs. at or after puberty spurt), and mode of bite-jumping (considerable vertical opening vs. limited vertical opening). These different features lead to different treatment effects on mandibular and TMJ growth, such as the intensity of possibly increased growth (clinically less significant vs. significant), the direction of enhanced growth (vertical vs. horizontal), and the stability of treatment changes (unstable vs. stable). The short-term or long-term post-treatment relapse mainly relates to the rebound of dental position.

CONCLUSION

The immediate effects of bite jumping functional appliances on the mandibular growth enhancement are convincing during actual treatment. This extra gain of growth might be sustainable during the short-term and long-term post-treatment period.

The role of type X collagen in facilitating and regulating endochondral ossification of articular cartilage

AUTHOR: Shen G Objective -This review was compiled to explore the role of type X collagen in growth, development and remodeling of articular cartilage by elucidating the linkage between the synthesis of this protein and the phenotypic changes in chondrogenesis and the onset of endochondral ossification.

DESIGN

The current studies closely dedicated to elucidating the role of type X collagen incorporating into chondrogenesis and endochondral ossification of articular cartilage were assessed and analyzed to allow for obtaining the mainstream consensus on the bio-molecular mechanism with which type X collagen functions in articular cartilage.

RESULTS

There are spatial and temporal correlations between synthesis of type X collagen and occurrence of endochondral ossification. The expression of type X collagen is confined within hypertrophic condrocytes and precedes the embark of endochondral bone formation. Type X collagen facilitates endochondral ossification by regulating matrix mineralization and compartmentalizing matrix components.

CONCLUSION

Type X collagen is a reliable marker for new bone formation in articular cartilage. The future clinical application of this collagen in inducing or mediating endochondral ossification is perceived, e.g. the fracture healing of synovial joints and adaptive remodeling of madibular condyle.

The lifetime of CFC substitutes studied by a network trained with chaotic mapping modified genetic algorithm and DFT calculations

The hydrohaloalkanes have attracted much attention as potential substitutes of chlorofluorocarbons (CFCs) that deplete the ozone layer and lead to great high global warming. Having a short atmospheric lifetime is very important for the potential substitutes that may also induce ozone depletion and yield high global warming gases to be put in use. Quantitative structure-activity relationship (QSAR) studies were presented for their lifetimes aided by the quantum chemistry parameters including net charges, Mulliken overlaps, E(HOMO) and E(LUMO) based on the density functional theory (DFT) at B3PW91 level, and the C-H bond dissociation energy based on AM1 calculations. Outstanding features of the logistic mapping, a simple chaotic system, especially the inherent ability to search the space of interest exhaustively have been utilized. The chaotic mapping aided genetic algorithm artificial neural network training scheme (CGANN) showed better performance than the conventional genetic algorithm ANN training when the structure of the data set was not favorable. The lifetimes of HFCs and HCs appeared to be greatly dependent on their energies of the highest occupied molecular orbitals. The perference of the RMSRE comparing to RMSE as objective function of ANN training was better for the samples of interest with relatively short lifetimes. C(2)H(6) and C(3)H(8) as potential green substitutes of CFCs present relatively short lifetimes.

Large scale association analysis for identification of genes underlying premature coronary heart disease: cumulative perspective from analysis of 111 candidate genes

BACKGROUND

to date, only three groups have reported data from large scale genetic association studies of coronary heart disease using a case control design.

METHODS AND RESULTS

to extend our initial report of 62 genes, we present data for 210 polymorphisms in 111 candidate genes genotyped in 352 white subjects with familial, premature coronary heart disease (onset age for men, 45; for women, 50) and a random sample of 418 population based whites. Multivariate logistic regression analysis was used to compare the distributions of genotypes between cases and the comparison group while controlling for age, sex, body mass, diabetes, and hypertension. Significant associations were found with polymorphisms in thrombospondin-4 (THBS4), thrombospondin-2 (THBS2) and plasminogen activator inhibitor-2 (PAI2), the strongest being with the A387P variant in THBS4 (p = 0.002). The THBS2 and THBS4 associations have since been replicated. We evaluated polymorphisms in 40 genes previously associated with coronary heart disease and found significant (p<0.05) associations with 10: ACE, APOE, F7, FGB, GP1BA, IL1RN, LRP1, MTHFR, SELP, and THPO. For five of these genes, the polymorphism associated in our study was different from that previously reported, suggesting linkage disequilibrium as an explanation for failure to replicate associations consistently across studies. We found strong linkage disequilibrium between polymorphisms within and between genes, especially on chromosome 1q22-q25, a region containing several candidate genes.

CONCLUSIONS

despite known caveats of genetic association studies, they can be an effective means of hypothesis generation and complement classic linkage studies for understanding the genetic basis of coronary heart disease.

Anti-proliferative effects induced by anti-CD4 human/murine chimeric antibody and murine anti-CD4 monoclonal antibody

The effects of chimeric anti-CD4 human/murine chimeric antibody and murine anti-CD4 monoclonal antibody (McAb) on the proliferation induced by anti-CD3 McAb, phytohemagglutinin (PHA), IL-2, and allogeneic cells were studied. The results showed that chimeric anti-CD4 antibody and murine anti-CD4 McAb could inhibit the proliferation induced by the above inducers and the inhibitory effects were related to the dosage of the antibodies.

The effect of astragapolysaccharide on the lymphocyte proliferation and airway inflammation in sensitized mice

In order to investigate the regulating role of Astragapolysaccharide (APS) in the mice model of asthmatic airway inflammation, the airway eosinophil number, spleen T lymphocyte proliferation, level of IL-2 production and their relationships were studied in sensitized mice and sensitized mice treated with different concentrations of APS. The results showed that the number of eosinophils as well as lymphocytes in the airway of the sensitized animals were significantly increased, and a marked positive correlation between the inflammation cells and spleen T lymphocyte proliferation was found. Moreover, there was a positive correlation between inflammation cells and the level of IL-2 production. The APS of given dosage could significantly reduce the number of eosinophils in the airway of the sensitized animals. At the same time the level of IL-2 secreted by spleen T lymphocytes stimulated with ConA was also significantly decreased and there was a marked positive correlation between them. Our results suggested that APS of given dosage could prevent antigen-induced the number of eosinophils infiltrating into the airway of sensitized mice and inhibit the proliferation and activation of lymphocyte and IL-2 production. Through its immuno-regulating effect, APS can be helpful in the treatment of asthma.

Adaptive vector quantization with codebook updating based on locality and history

In this paper, we propose two techniques that are applicable to any adaptive vector quantization (AVQ) systems. The first one is called the locality-based codebook updating: when performing a codebook updating, we update the operational codebook using not only the current input vector but also the codewords at all positions within a selected neighboring area (called the locality), while the operational codebook is organized in a "cache" manner. This technique is rationalized by the high correlation cross neighboring vectors that facilitates a more efficient coding of the indices of the codewords chosen from the codebook. The second technique is called the history aid, which makes use of the information of previously coded vectors to quantize the current input vector if it is used to update the operational codebook. A more effective AVQ system is obtained by combining together the history aid and the locality-based updating. Extensive simulations are carried out to demonstrate the improved results achieved by our AVQ systems. Particularly, when the operational codebook size is relatively small, the improvement over a benchmark AVQ system--the generalized threshold replenishment (GTR)--is drastic. For example, when the size is 32, testing on a nonstationary signal (containing frames from different video sequences, ordered in the concatenating or interleaving format) shows that the combination of history aid and locality-based updating offers more than 4 dB gain over GTR at 0.5 bpp.

Nuclear inelastic x-ray scattering of FeO to 48 GPa

The partial density of vibrational states has been measured for Fe in compressed FeO (wüstite) using nuclear resonant inelastic x-ray scattering. Substantial changes have been observed in the overall shape of the density of states close to the magnetic transition around 20 GPa from the paramagnetic (low pressure) to the antiferromagnetic (high pressure) state. The results indicate that strong magnetoelastic coupling in FeO is the driving force behind the changes in the phonon spectrum of FeO. The paper presents the first observation of changes in the density of terahertz acoustic phonon states under magnetic transition at high pressure.

High-precision U-series dating of Locality 1 at Zhoukoudian, China

Thermal ionization mass spectrometric(230)Th/(234)U dating has been carried out on intercalated speleothem samples from the limestone cave occupied by Homo erectus at Zhoukoudian, China. The samples were recently collected in proper stratigraphic context after detailed field examinations. The results show that the age of the No. 5 Skull from Layer 3 is >400 ka, possibly in the range of about 400-500 ka, and that the hominid fossils from the lower strata are at least 600 ka and possibly >800 ka, much older than previously thought. The near-equilibrium(230)Th/(234)U ratios and internal consistency of the dates and stratigraphy lend credence to the results and allow us to comment on their important implications for human evolution.

[A summary description of development in immunosensor]

In this review, an introduction to the concept and fundamental principles of immunosensor is given, and immunosensor is classified into many types according to the difference of transducers, each type being compared with others and explicated in derivation and developing process respectively. Two problems about the fabrication of immunosensor, which are immobilization and reproductivity, are addressed fleetly. In addition, the application and developing tendency of immunosensor are described briefly.

Analysis of the 1991-2000 influenza epidemic in Guangdong Province, China

Influenza surveillance networks in Guangdong were established to investigate the epidemiological characteristics of influenza and influenza epidemics. Influenza activity peaked annually from March to July in Guangdong in 1991-2000; influenza H3N2 predominated in the epidemic (7 years of 10); the outbreak of influenza in 1996 was the remarkable result of antigenic drift of H3N2 strain. Ten isolates of H9N2 strains were discovered from human subjects in 1998 and 1999: chicken strains isolated after the Hong Kong fowl influenza outbreak. It was found that there was just one influenza activity season per annum in Guangdong and that the influenza H3N2 subtype still predominates in Guangdong. Further research into the pathogenicity of influenza H9N2 in humans warranted.

[A cephalometric investigation on Shanghainese with normal occlusion using Ricketts analysis]

OBJECTIVE

To provide a database for orthodontic diagnosis, treatment planning and treatment evaluation.

METHODS

Cephalograms taken from 121 Shanghainese (57 adolescents and 64 adults) with normal occlusion were traced and examined using Ricketts analysis.

RESULTS

(1) In adolescent group, the angle of mandibular arc and facial contour were larger in male than in female. (2)In adults group, the angle of mandibular arc and genial angle were larger in male than in female, whilst the lower facial height and the convexity of lower incisor were smaller in male than in female. (3) The angle of mandibular arc, the convexity of lower incisor and the position of upper first molar were larger in adults than in adolescents,whilst the convexity of A was smaller in adults than in adolescents.

CONCLUSION

In adolescents, the ramus and maxilla grow more in male than in female. In adults, chin and ramus grow more in male than those in female.

Oxidative dimerization in metallothionein is a result of intermolecular disulphide bonds between cysteines in the alpha-domain

Upon storage under aerobic conditions metallothioneins (MTs) form a new species, which is characterized by a molecular mass approximately twice the size of monomeric MT and shifted (113/111)Cd- and (1)H-NMR resonances. The investigation of this oxidative dimerization process by NMR spectroscopy allowed us to structurally characterize this MT species that has been described to occur in vivo and might be synthesized under conditions of oxidative stress. The oxidative dimer was characterized by the formation of an intermolecular cysteine disulphide bond involving the alpha-domain, and a detailed analysis of chemical shift changes and intermolecular nuclear Overhauser effects points towards a disulphide bond involving Cys(36). In contrast to the metal-bridged (non-oxidative) dimerization, the metal-cysteine cluster structures in both MT domains remain intact and no conformational exchange or metal-metal exchange was observed. Also in contrast to the many recently reported oxidative processes which involve the beta-domain cysteine groups and result in the increased dynamics of the bound metal ions in this N-terminal domain, we found no evidence for any increased dynamics in the alpha-domain metals following this oxidation. Therefore these findings provide additional corroboration that metal binding in the C-terminal alpha-domain is rather tight, even under conditions of a changing cellular oxidation potential, compared with the more labile/dynamic nature of the metals in the N-terminal beta-domain cluster under similar conditions.

Stability and structure of MgSiO3 perovskite to 2300-kilometer depth in Earth's mantle

Unexplained features have been observed seismically near the middle (approximately 1700-kilometer depth) and bottom of the Earth's lower mantle, and these could have important implications for the dynamics and evolution of the planet. (Mg,Fe)SiO3 perovskite is expected to be the dominant mineral in the deep mantle, but experimental results are discrepant regarding its stability and structure. Here we report in situ x-ray diffraction observations of (Mg,Fe)SiO3 perovskite at conditions (50 to 106 gigapascals, 1600 to 2400 kelvin) close to a mantle geotherm from three different starting materials, (Mg0.9Fe0.1)SiO enstatite, MgSiO3 glass, and an MgO+SiO2 mixture. Our results confirm the stability of (Mg,Fe)SiO3 perovskite to at least 2300-kilometer depth in the mantle. However, diffraction patterns above 83 gigapascals and 1700 kelvin (1900-kilometer depth) cannot presently rule out a possible transformation from Pbnm perovskite to one of three other possible perovskite structures with space group P2(1)/m, Pmmn, or P4(2)/nmc.

Effects of nimodipine on changes of endothelin after head injury in rabbits

OBJECTIVE

To investigate the effects of nimodipine on changes of endothelin after head injury.

METHODS

Sixty-five adult rabbits were randomized into an injury group (IG, n=30), a nimodipine-treatment group (NTG, n=30) and a control group (CG, n=5). With their heads unfixed, the animals in IG and NTG were injured in the frontal-parietal zone with BIM-II bioimpact. Blood samples and brain tissue were collected before and after injury. The endothelin level was measured with RIA.

RESULTS

The endothelin level in plasma and brain tissue was significantly increased 24 hours after injury. At the 8th or/and 24th hours postinjury, the endothelin level was significantly lower in NTG than that in IG.

CONCLUSIONS

Nimodipine can prevent endothelin from elevation and act as a practical endothelin antagonist after head injury clinically.

Characterization of highly sulfated cyclodextrins

A class of highly sulfated cyclodextrins (HS-CDs) was developed for enantiomeric separation of chiral compounds by capillary electrophoresis (CE). The HS-CDs were produced by a facile single-step direct sulfation of cyclodextrin using sulfur trioxide-trimethylamine complex in dimethylformamide. Characterization of the HS-CDs by electrospray ionization mass spectrometry and by CE using a well-established indirect detection method indicated the species have very narrow heterogeneity in terms of degree of sulfation. Elemental analysis of the HS-alpha-, beta- and gamma-CDs showed that the average sulfate contents were 11, 12, and 13 per CD molecule, respectively. The 13C NMR of HS-CDs is consistent with the structural assignment of nearly complete sulfation at C-6 primary hydroxyl groups and partial sulfation at the C-2 secondary hydroxyls (>70%), while the C-3 hydroxyls remain unsubstituted. Enantiomeric separation by CE using the HS-CDs as chiral selectors showed that HS-alpha-, beta- and gamma-CDs complement each other by exhibiting different chiral selectivities, resulting in resolution of many chiral neutral, acidic and basic compounds of greatly varying structural features. The part of HS-CD that interacts with the guest molecule during complexation and, therefore, the receiving end of the cyclodextrin hydrophobic bucket was surrounded with largely regiospecifically substituted C-2 sulfates and intact C-3 hydroxyls, both at the equatorial positions. Such global regiospecific structural arrangement in HS-CDs provides differential diasteroisomeric complexation is proposed to be the principal contributing factor in the resolving racemates.

Induction of cholesteryl ester transfer protein in adipose tissue and plasma of the fructose-fed hamster

Cholesteryl ester transfer protein (CETP) plays a pivotal role in the reverse transport of cholesterol and in the remodeling of circulating lipoproteins. While plasma and adipose tissue levels of CETP are affected by a variety of metabolic conditions, the extent of the effects of dietary factors, other than high cholesterol feeding, are not well understood. To further explore this paradigm, male Golden Syrian hamsters were fed for 4 weeks with a 60%-enriched fructose diet (F) and were compared to a matched group of animals fed with a normal chow diet (N). After feeding for 4 weeks, plasma insulin concentrations were lower in animals fed fructose than in control animals (F: 3.3+/-0.8 vs N: 7.4+/-1.9 ng/mL; p<0.03), but there was no significant difference in plasma glucose concentrations between the two groups (F: 138+/-7 vs N: 148+/-10 mg/dL; p>0.05). Fructose-fed animals showed significant increases in plasma triglyceride (F: 269+/-22 vs N: 165+/-22 mg/dL; p<0.01) and plasma cholesterol (F: 150+/-10 vs N: 113+/-6 mg/dL; p<0.02) concentrations compared with control animals. Total CETP activity and immunoreactive mass were higher in the plasma of fructose-fed animals that in that of controls (F: 1036+/-70 vs N: 826+/-43 pmol/h/mL, p<0.04 and F: 24.5+/-3.1 vs N: 37.5+/-4.3 AU, p<0.02, respectively). Adipose tissue CETP mRNA levels, assessed by the very sensitive ribonuclease protection assay, were 53% higher in fructose-fed animals than in controls (F: 14.1+/-2.0 vs N: 9.2+/-1.0 AU over a rRNA control; p<0.04). Adipose tissue CETP activity and immunoreactive mass also showed a statistically significant increase in the fructose-fed hamsters compared with those fed a normal diet (p<0.04). In conclusion, fructose feeding in Syrian hamsters induces a mixed dyslipidemia. These metabolic changes are accompanied by a significant increase in CETP levels, both in plasma and in adipose tissue. This phenomenon suggests that the increase in the expression of adipose tissue CETP may be caused either by the ambient hypercholesterolemia resulting from fructose feeding or by an attenuation of a possible inhibitory effect of plasma insulin concentrations on the expression of adipose tissue CETP in this feeding paradigm.