Abnormal correlation between phase transformation and cooling rate for pure metals

This work aims to achieve deep insight into the phenomenon of phase transformation upon rapid cooling in metal systems and reveal the physical meaning of scatter in the time taken to reach crystallization. The total number of pure metals considered in this work accounts for 14. Taking pure copper as an example, the correlation between phase selection of crystal or glass and cooling rate was investigated using molecular dynamic simulations. The obtained results demonstrate that there exists a cooling rate region of 6.3 × 10¹¹–16.6 × 10¹¹ K/s, in which crystalline fractions largely fluctuate along with cooling rates. Glass transformation in this cooling rate region is determined by atomic structure fluctuation, which is controlled by thermodynamic factors. According to the feature of bond-orientation order at different cooling rates, we propose two mechanisms of glass formation: (i) kinetic retardation of atom rearrangement or structural relaxation at a high cooling rate; and (ii) competition of icosahedral order against crystal order near the critical cooling rate.

Early enteral and parenteral nutrition on immune functions of neurocritically ill patients

This study was designed to investigate the influence of early enteral and parenteral nutrition on immune functions of neurocritically ill patients. Patients who were admitted to the neurological intensive care unit (ICU) of The Second Affiliated Hospital of Zhengzhou University between May 2014 and January 2016 were selected. They had been hospitalized for more than one week and received enteral nutrition (EN) via nasogastric tube, with a gross energy of 25 kcal/(Kg • d). Patients were divided into EN group, EN + early PN (EPN) group and EN + supplemental PN (SPN) group according to the time of PN support. Differences in patients’ general information and changes in serum protein and immune indexes were compared between the three groups. On admission, patients’ Glasgow coma scale (GCS), age, immune functions and protein indexes had no obvious differences between the three groups. After nutritional support, serum protein level reduced in the EN group while prealbumin (PALB) and retinol binding protein (RBP) increased in the EN + EPN group and EN + SPN group after one week of admission to hospital, and the differences were statistically significant (p less than 0.05). Total protein (TP), albumin (ALB), PALB and transferrin (TRF) increased significantly in the EN + EPN group and EN + SPN group compared with the EN group (p < 0.05); before and after treatment, an increase was found in ALB in the EN + EPN group in comparison with EN + SPN group, with a notable difference (p < 0.05); C3, C4, immunoglobulin M (IgM) and immunoglobulin A (IgA) increased in the EN + SPN group after nutritional support compared with before treatment, and the difference was statistically significant (p < 0.05). Moreover, immunoglobulin G (IgG) and IgA in the EN + EPN group increased after nutritional support comparing to prior to nutritional support, and the difference was statistically significant (p < 0.05). After nutritional treatment, IgA and IgG increased markedly in the EN + EPN group, and there was a statistical significance between the groups (p < 0.05); the EN + EPN group and EN + SPN group exceeded the EN group in total lymphocyte count (TLC), and the difference had a statistical significance (p less than 0.05). These results demonstrate that neurocritically ill patients achieving the target energy can avoid malnutrition and immunodeficiency; serum protein decrease can cause malnutrition after one week of EN support; and enteral and parenteral nutrition can improve nutritional and immune indicators of neurocritically ill patients in the acute phase. In addition, EPN is more likely to improve malnutrition and immune functions of critical patients than SPN.

Correlation between magnetic resonance perfusion weighted imaging of radiation brain injury and pathology

We used magnetic resonance perfusion weighted imaging and pathological evaluation to examine different stages of radiation-induced brain injury and to investigate the correlation between the relative cerebral blood volume (rCBV) ratio and vascular endothelial growth factor (VEGF). Thirty adult rats were randomly divided into 2 groups: control and radiation group. The control group was not subjected to irradiation. The irradiation group rats were examined by magnetic resonance imaging and magnetic resonance perfusion weighted imaging at 1, 3, 6, 9, and 12 months after radiation treatment. We measured the rCBV, mean transit time, and time to peak. Hematoxylin and eosin staining, immunohistochemical staining, and electron microscopy were performed. VEGF absorbance was evaluated by immunohistochemical staining. Compared with the control group, the differences in rCBV, mean transit time, time to peak, and VEGF absorbance after 3 months were statistically significant (P < 0.05). rCBV was positively correlated with VEGF (r = 0.94, P < 0.05). Magnetic resonance perfusion weighted imaging can reflect pathophysiological changes in brain tissue after irradiation. Decreased expression of VEGF plays a critical role in the pathogenesis of radiation-induced brain injury.

Analysis of an "off-ladder" allele at the Penta D short tandem repeat locus

Kinship testing of a father and his son from Guangxi, China, the location of the Zhuang minority people, was performed using the PowerPlex® 18D System with a short tandem repeat typing kit. The results indicated that both the father and his son had an off-ladder allele at the Penta D locus, with a genetic size larger than that of the maximal standard allelic ladder. To further identify this locus, monogenic amplification, gene cloning, and genetic sequencing were performed. Sequencing analysis demonstrated that the fragment size of the Penta D-OL locus was 469 bp and the core sequence was [AAAGA]21, also called Penta D-21. The rare Penta D-21 allele was found to be distributed among the Zhuang population from the Guangxi Zhuang Autonomous Region of China; therefore, this study improved the range of DNA data available for this locus and enhanced our ability for individual identification of gene loci.

Eosinophil cationic protein mRNA expression in children with bronchial asthma

Studies have shown that eosinophils are closely related to pathogenesis of bronchial asthma. Eosinophils release eosinophil cationic protein (ECP), which plays an important role in infection and allergic reactions. Serum ECP mRNA expression in children with bronchial asthma has not been adequately investigated. We analyzed serum ECP mRNA expression in 63 children with bronchial asthma and 21 healthy children by using reverse-transcriptase polymerase chain reaction to understand the role of ECP in children with bronchial asthma. The children with bronchial asthma were segregated into acute-phase and stable-phase groups, based on the severity of the illness. Serum ECP mRNA expression in children with bronchial asthma (0.375 ± 0.04) was significantly higher than that in healthy controls (0.20 ± 0.02; P < 0.05). Additionally, children in the acute-phase group showed higher ECP mRNA expression level (0.44 ± 0.06) than those in the stable-phase (0.31 ± 0.03) and healthy control groups (0.20 ± 0.02; P < 0.05), while the level in the stable-phase (0.31 ± 0.03) was markedly higher than that in the healthy control group (0.20 ± 0.02; P < 0.05). Detection of serum ECP mRNA expression level has possible applications in the diagnosis and treatment of children with bronchial asthma.

Passively Q-switched Nd:YAG/Cr(4+):YAG bonded crystal microchip laser operating at 1112 nm and its application for second-harmonic generation

A passively Q-switched Nd:YAG/Cr⁴⁺:YAG microchip laser operating at 1112 nm is demonstrated. Under a pump power of 5.5 W, a maximum average output power of 623 mW was obtained with T=6% output coupler, corresponding to an optical-to-optical conversion efficiency of 11.3% and a slope efficiency of 19.5%. The minimum pulse width was 2.8 ns, the pulse energy and peak power were 39.3 μJ and 14 kW, respectively. Additionally, based on the 1112 nm laser, a 230 mW 556 nm green-yellow laser was achieved within an LBO crystal.

Assessment of correlation between pre-miRNA-1757 polymorphism and chicken performance traits

Single nucleotide polymorphism in microRNAs (miRNA) may influence their target gene selection and regulation efficiency, leading to animal phenotypic variation. The aim of this study was to evaluate the possible effect of single nucleotide polymorphisms in the miRNA-1757 gene precursor region (pre-mir-1757) on economic-related traits in chicken. Genotyping was performed using Sequenom MassArray® iPLEX GOLD System. Association analysis was performed using SPSS19.0. The data showed that the G/C polymorphism was significantly correlated with semi-evisceration weight, evisceration weight, carcass weight, body weight at 10 weeks of age, shank length at 4 weeks of age, pectoral angle at 8 weeks of age, and body slanting length and pelvis breadth at 12 weeks of age (P < 0.05), and led to the alteration of the RNA secondary structure of pre-mir-1757. Our results provide useful information for further annotation studies of miRNA function.

Ultra-sparse metasurface for high reflection of low-frequency sound based on artificial Mie resonances

Acoustic metamaterials offer great flexibility for manipulating sound waves and promise unprecedented functionality, ranging from transformation acoustics, super-resolution imaging to acoustic cloaking. However, the design of acoustic metamaterials with exciting functionality remains challenging with traditional approaches using classic acoustic elements such as Helmholtz resonators and membranes. Here we demonstrate an ultraslow-fluid-like particle with intense artificial Mie resonances for low-frequency airborne sound. Eigenstate analysis and effective parameter retrieval show two individual negative bands in the single-size unit cell, one of which exhibits a negative bulk modulus supported by the monopolar Mie resonance, whereas the other exhibits a negative mass density induced by the dipolar Mie resonance. The unique single-negative nature is used to develop an ultra-sparse subwavelength metasurface with high reflectance for low-frequency sound. We demonstrate a 0.15λ-thick, 15%-filling ratio metasurface with an insertion loss over 93.4%. The designed Mie resonators provide diverse routes to construct novel acoustic devices with versatile applications.

Reconstruction of maxillary defects with free fibula flap assisted by computer techniques

OBJECTIVE

Free fibula flaps are widely used for maxillary reconstruction. The three-dimensional position of the fibula flap is very difficult to control in conventional operations based solely on the surgeon's experience. We aimed to improve this surgery by using computerized techniques.

METHODS

Twenty-seven patients with maxillary tumors underwent maxillectomy and free fibula flap reconstruction in our department between 2011 and 2013. Virtual planning and surgical navigation were used for eight patients, and conventional surgery was performed in 19 patients. The three-dimensional fibular positions were evaluated in the two groups. Differences between the postoperative position of the fibular segments and the virtual plans were evaluated in the computer-assisted surgery group.

RESULTS

The three-dimensional position of the fibula flap in the computer-assisted surgery group, including the vertical distance (p = 0.013), horizontal position (p = 0.019) and extension of the posterior end (p = 0.041), was significantly more accurate and nearer to the ideal position than that in the conventional surgery group. The average difference between the actual postoperative position of the fibular segments and the virtual plan in the computer-assisted surgery group was <5 mm.

CONCLUSION

Application of computer-assisted techniques such as virtual planning and surgical navigation significantly improve the clinical outcomes of maxillary reconstruction with free fibula flaps.

Propofol inhibits burn injury-induced hyperpermeability through an apoptotic signal pathway in microvascular endothelial cells

Recent studies have revealed that an intrinsic apoptotic signaling cascade is involved in vascular hyperpermeability and endothelial barrier dysfunction. Propofol (2,6-diisopropylphenol) has also been reported to inhibit apoptotic signaling by regulating mitochondrial permeability transition pore (mPTP) opening and caspase-3 activation. Here, we investigated whether propofol could alleviate burn serum-induced endothelial hyperpermeability through the inhibition of the intrinsic apoptotic signaling cascade. Rat lung microvascular endothelial cells (RLMVECs) were pretreated with propofol at various concentrations, followed by stimulation with burn serum, obtained from burn-injury rats. Monolayer permeability was determined by transendothelial electrical resistance. Mitochondrial release of cytochrome C was measured by ELISA. Bax and Bcl-2 expression and mitochondrial release of second mitochondrial-derived activator of caspases (smac) were detected by Western blotting. Caspase-3 activity was assessed by fluorometric assay; mitochondrial membrane potential (Δψm) was determined with JC-1 (a potential-sensitive fluorescent dye). Intracellular ATP content was assayed using a commercial kit, and reactive oxygen species (ROS) were measured by dichlorodihydrofluorescein diacetate (DCFH-DA). Burn serum significantly increased monolayer permeability (P<0.05), and this effect could be inhibited by propofol (P<0.05). Compared with a sham treatment group, intrinsic apoptotic signaling activation - indicated by Bax overexpression, Bcl-2 downregulation, Δψm reduction, decreased intracellular ATP level, increased cytosolic cytochrome C and smac, and caspase-3 activation - was observed in the vehicle group. Propofol not only attenuated these alterations (P<0.05 for all), but also significantly decreased burn-induced ROS production (P<0.05). Propofol attenuated burn-induced RLMVEC monolayer hyperpermeability by regulating the intrinsic apoptotic signaling pathway.

Multivariate analysis of molecular markers in peripheral blood associated with recurrence and metastasis of hepatocellular carcinoma

Invasion, metastasis, and recurrence are the most common causes of death in patients with hepatocellular carcinoma (HCC) and are therefore critical factors for both therapy and prognosis. Current methods for diagnosis of HCC rely mainly on serological markers such as alpha-fetoprotein and liver enzymes, together with physical assessment and imaging techniques. The availability of more accurate serum markers may facilitate screening and early diagnosis, which will improve prognosis. This retrospective cohort analysis included 50 consecutive patients with cirrhosis and single or multifocal HCC and 40 control subjects with no liver disease or risk factors for viral hepatitis. Expression of epidermal growth factor-like domain 7 (EGFL7), osteopontin (OPN), and prostaglandin E2 (PGE2) were detected using an enzyme-linked immunosorbent assay. The mean serum levels of EGFL7, OPN, and PGE2 in the HCC group were 132.11 pg/mL, 11.77 ng/mL, and 179.37 pg/mL, respectively, which were all significantly higher than the levels in the control group (23.03 pg/mL, 2.31 ng/mL, and 47.36 pg/mL, respectively; P < 0.001). Serum levels of EGFL7, OPN, and PGE2 levels may thus be useful for screening and surveillance of HCC among high-risk populations, and have the potential to improve prognosis of these patients.

Surgical safety distances in the infratemporal fossa: three-dimensional measurement study

The wedge-shaped infratemporal fossa is a constricted space and has long been a surgical challenge, mainly due to difficulties in access. Three-dimensional (3D) reconstruction of the skull, internal carotid artery (ICA), and internal jugular vein (IJV) was carried out using enhanced computed tomography (CT) data, to measure the safety distances in relation to infratemporal fossa surgery. Fifty enhanced CT datasets were selected to reconstruct 3D images by segmentation technique. The anatomical routes of the ICA, IJV, and the styloid process (SP) were observed. The following were measured: SP length, height of the pterygoid plates (PP height), distances from the pterygoid process (antero-inferior and anterosuperior border) to the leading edge of the ICA (PP-ICA (inferior), PP-ICA (superior)), and distance between the most prominent point of the zygomatic arch and the medial pterygoid plate (Zyg-MPP). The mean measurements of SP length, PP height, and the distances PP-ICA (inferior), PP-ICA (superior), and Zyg-MPP were 30.64 mm, 26.61 mm, 31.16 mm, 34.37 mm, and 51.37 mm, respectively. No significant differences were observed by age group, except the distance of PP-ICA (inferior) on the left side. In centres without intraoperative navigation facilities, proper knowledge of the anatomy, particularly of bony landmarks and the safe distances to nearby neurovascular structures, can provide useful information to ensure safe operations.

Role of mechanical strain and estrogen in modulating osteogenic differentiation of mesenchymal stem cells (MSCs) from normal and ovariectomized rats

Bone's adaptability to loading depends upon the process of bone remodeling. This adaptive mechanism is restricted in postmenopausal osteoporosis. Differentiation of mesenchymal stem cells (MSCs) is crucial to bone remodeling and regeneration. It is well accepted that mechanical loading influences the fate of MSC differentiation. The aim of this study was to explore the possible restricted mechanism in osteoporotic condition, through investigating response of MSCs from both sham-operated and ovariectomized rats. MSCs were exposed to estrogen and mechanical strain (2%, 1Hz, 6h/day) for 3 days. Osteogenic differentiation and β-catenin protein in MSCs were examined. Exposure to estrogen and mechanical strain alone enhanced expression of Runx2 (Cbfα1), type I collagen (ColI) and activated β-catenin protein in MSCs from both sham-operated and OVX rats. MSCs from both sham-operated and OVX rats stimulated with both mechanical strain and estrogen had higher expression of osteogenic genes and activated β-catenin protein than these cells exposed to estrogen and mechanical strain alone. Osteoporotic MSCs had lower expression of osteogenic genes and protein in the absence and presence of stimulation than did MSCs from sham-operated rats. Cumulatively, our results indicate that mechanical strain and estrogen in vitro enhance osteogenic potential and activation of β-catenin in MSCs from both sham-operated and OVX rats. Estrogen augments strain-induced osteogenic potential and activity of β-catenin in MSCs.

Histone demethylase retinoblastoma binding protein 2 regulates the expression of α-smooth muscle actin and vimentin in cirrhotic livers

Liver cirrhosis is one of the most common diseases of Chinese patients. Herein, we report the high expression of a newly identified histone 3 lysine 4 demethylase, retinoblastoma binding protein 2 (RBP2), and its role in liver cirrhosis in humans. The siRNA knockdown of RBP2 expression in hepatic stellate cells (HSCs) reduced levels of α-smooth muscle actin (α-SMA) and vimentin and decreased the proliferation of HSCs; and overexpression of RBP2 increased α-SMA and vimentin levels. Treatment with transforming growth factor β (TGF-β) upregulated the expression of RBP2, α-SMA, and vimentin, and the siRNA knockdown of RBP2 expression attenuated TGF-β-mediated upregulation of α-SMA and vimentin expression and HSC proliferation. Furthermore, RBP2 was highly expressed in cirrhotic rat livers. Therefore, RBP2 may participate in the pathogenesis of liver cirrhosis by regulating the expression of α-SMA and vimentin. RBP2 may be a useful marker for the diagnosis and treatment of liver cirrhosis.

Crosstalk of Ras and Rho: activation of RhoA abates Kras-induced liver tumorigenesis in transgenic zebrafish models

RAS and Rho small GTPases are key molecular switches that control cell dynamics, cell growth and tissue development through their distinct signaling pathways. Although much has been learnt about their individual functions in both cell and animal models, the physiological and pathophysiological consequences of their signaling crosstalk in multi-cellular context in vivo remain largely unknown, especially in liver development and liver tumorigenesis. Furthermore, the roles of RhoA in RAS-mediated transformation and their crosstalk in vitro remain highly controversial. When challenged with carcinogens, zebrafish developed liver cancer that resembles the human liver cancer both molecularly and histopathologically. Capitalizing on the growing importance and relevance of zebrafish (Danio rerio) as an alternate cancer model, we have generated liver-specific, Tet-on-inducible transgenic lines expressing oncogenic Kras(G12V), RhoA, constitutively active RhoA(G14V) or dominant-negative RhoA(T19N). Double-transgenic lines expressing Kras(G12V) with one of the three RhoA genes were also generated. Based on quantitative bioimaging and molecular markers for genetic and signaling aberrations, we showed that the induced expression of oncogenic Kras during early development led to liver enlargement and hepatocyte proliferation, associated with elevated Erk phosphorylation, activation of Akt2 and modulation of its two downstream targets, p21Cip and S6 kinase. Such an increase in liver size and Akt2 expression was augmented by dominant-negative RhoA(T19N), but was abrogated by the constitutive-active RhoA(G14V). Consequently, induced expression of the oncogenic Kras in adult transgenic fish led to the development of hepatocellular carcinomas. Survival studies further revealed that the co-expression of dominant-negative RhoA(T19N) with oncogenic Kras increased the mortality rate compared with the other single or double-transgenic lines. This study provides evidence of the previously unappreciated signaling crosstalk between Kras and RhoA in regulating liver overgrowth and liver tumorigenesis. Our results also implicate that activating Rho could be beneficial to suppress the Kras-induced liver malignancies.

Unique roles of Schistosoma japonicum protein Sj16 to induce IFN-γ and IL-10 producing CD4(+)CD25(+) regulatory T cells in vitro and in vivo

Various proteins are expressed during different stages of schistosome development that are essential for cercarial penetration of vertebrate skin and evasion of host immune response. CD4(+)CD25(+) regulatory T cells are important in modulating immune responses towards helminth infections. Schistosoma japonicum protein Sj16 present in the secretions of schistosomula has been shown to have anti-inflammatory effects; however, it is uncertain whether Sj16 can induce CD4(+)CD25(+) regulatory T cells to participate in the regulation of early infection. In this study, we demonstrate a relationship between recombinant Sj16 (rSj16) and the induction of CD4(+)CD25(+) Foxp3(+) regulatory T cells. An increase in CD4(+)CD25(+) T cells was observed both in splenic cells from mice injected with rSj16 and the cells pretreated with rSj16, respectively. The induced CD4(+)CD25(+) T cells suppressed CD4(+)CD25(-) T-cell proliferation; furthermore, IFN-γ and IL-10 released from rSj16-stimulated cells contribute to this suppression. Additionally, rSj16-treated bone marrow dendritic cells (BMDCs) demonstrate an immature phenotype and play a role in the conversion of CD4(+)CD25(-) T cells into suppressive CD4(+)CD25(+) regulatory T cells. Our study identified a new CD4(+)CD25(+) T-cell population that induced by rSj16 and suggests that an IFN-γ-biased microenvironment during early infection of schistosome may favour the establishment of infection.

First-principles calculation of structural, mechanical, magnetic and thermodynamic properties for γ-M23C6 (M = Fe, Cr) compounds

We report the results of our first-principles calculations of structural stability, mechanical, magnetic, and thermodynamic properties for γ-M(23)C(6) (M = Fe, Cr) compounds with each of the four metal Wyckoff sites being occupied in turn by Fe. The thermodynamic properties and the temperature dependence of the mechanical behavior of γ-M(23)C(6) compounds are investigated based on the quasi-harmonic Debye model. The results show that the thermodynamic properties of γ-M(23)C(6) (M = Fe, Cr) compounds are more dependent on the position of Fe atoms than the amount of Fe.

Band structures of phononic-crystal plates in the form of a sandwich-layered structure

This study investigates the propagation of Lamb waves in phononic-crystal plates in the form of a sandwich-layered structure. The composite plates are composed of periodic layers bilaterally deposited on both sides of the homogeneous core layer. Using the analyses of the band structures and the transmission spectra, it is revealed that the core layer may induce significant modulations to the lower-order Lamb modes. The modulations are ascribed to the reshaped particle displacement fields of the eigenmodes. Prominently, the core layer made of soft material (rubber) combines the identical eigenmodes of the periodic layers into a pair of asymmetric and symmetric modes in which case the periodic layers vibrate independently. However, the core layer made of hard material (tungsten) or medium hardness material (silicon) couples the periodic layers tightly, in which case the composites vibrate as a whole. In addition, it is found that the phononic band gaps are very sensitive to the thickness of the core layer; this could be indispensable to practical applications such as bandgap tuning.

Laminar shear stress promotes endothelial cell migration and inhibits cell apoptosis in the presence of hydroxyurea

Cell migration plays important roles in both physiological and pathological processes. Recent studies have shown that hydroxyurea, which is an anti-proliferative inhibitor, can affect cell morphology and specific gene expression of endothelial cells (ECs). In vivo, the functions of ECs are modulated by shear stress. It is well known that shear stress can have effects on EC migration by affecting cell morphology, cytoskeletal arrangement and cell-cell junction, and activating mechanosensors, inducing the changes of signaling pathways, and then increasing or decreasing the expression of gene and protein. However, the influences of hydroxyurea on EC function under shear stress are still unclear. In present study, we investigated the effects of hydroxyurea on EC proliferation, apoptosis and migration under laminar shear stress. The results showed that hydroxyurea prevented growth of ECs in a dose-dependent manner. Hydroxyurea at 2 mM completely inhibited the proliferation of ECs. The results also demonstrated that hydroxyurea induced EC apoptosis, but it was inhibited by 15.27 dyn/cm2 laminar shear stress. Furthermore, shear stress induced cell migration in the presence of hydroxyurea. Therefore, 2 mM hydroxyurea, which completely inhibited the proliferation of HUVECs, could be used to eliminate any confounding effect of shear stress on proliferation in shear stress-induced cell migration. These results also do confirm that shear stress plays important roles in achieving and maintaining the stabilization of ECs.

Assessment of effects of the rising atmospheric nitrogen deposition on nitrogen uptake and long-term water-use efficiency of plants using nitrogen and carbon stable isotopes

This study assesses the effects of the atmospheric nitrogen (N) deposition on the N uptake and the long-term water-use efficiency of two C(3) plants (Agropyron cristatum and Leymus chinensis) and two C(4) plants (Amaranthus retroflexus and Setaria viridis) using N and C stable isotopes. In addition, this study explores the potential correlation between leaf N isotope (δ(15)N) values and leaf C isotope (δ(13)C) values. This experiment shows that the atmospheric N deposition has significant effects on the N uptake, δ(15)N and leaf N content (N(m)) of C(3) plants. As the atmospheric N deposition rises, the proportion and the amount of N absorbed from the simulated atmospheric deposition become higher, and the δ(15)N and N(m) of the two C(3) plants both also increase, suggesting that the rising atmospheric N deposition is beneficial for C(3) plants. However, C(4) plants display different patterns in their N uptake and in their variations of δ(15)N and N(m) from those of C(3) plants. C(4) plants absorb less N from the atmospheric deposition, and the leaf N(m) does not change with the elevated atmospheric N deposition. Photosynthetic pathways may account for the differences between C(3) and C(4) plants. This study also shows that atmospheric N deposition does not play a role in determining the δ(13)C and in the long-term water-use efficiency of C(3) and C(4) plants, suggesting that the long-term water-use pattern of the plants does not change with the atmospheric N input. In addition, this study does not observe any relationship between leaf δ(15)N and leaf δ(13)C in both C(3) and C(4) plants.

The small GTPase Cdc42 promotes membrane protrusion during polar body emission via ARP2-nucleated actin polymerization

Polar body emission is a specialized cell division throughout the animal kingdom, serving to reduce chromosome ploidy while preserving the egg cytoplasm. Critical to polar body emission are the asymmetric positioning of the meiotic spindle prior to anaphase, with one pole attached to the oocyte cortex, and the simultaneous membrane protrusion during subsequent cytokinesis. We have shown that, during Xenopus oocyte maturation, the small GTPase Cdc42 promotes membrane protrusion while a classical RhoA contractile ring forms and constricts at the base of the protrusion. We report here that treating oocytes with low concentrations of nocodazole diminished the size of metaphase I spindles and prevented polar body emission, and yet an active Cdc42 cap of correspondingly diminished size still developed, on time, atop of the spindle pole. Conversely, treating oocytes with low concentrations of taxol resulted in a spindle with multiple poles attached to the cortex, but still each of these poles were associated with activated cortical Cdc42 at the appropriate time. Therefore, the asymmetric positioning of the meiotic spindle with one pole anchored to the cortex is a prerequisite for Cdc42 activation. Furthermore, we demonstrated that the Cdc42-regulated F-actin nucleator ARP2/3 complex was similarly localized at the cortex of the protruding polar body membrane, suggesting that Cdc42 promotes membrane protrusion through an F-actin meshwork mechanism. Finally, we demonstrated that Cdc42 and RhoA formed similarly complementary activity zones during egg activation and that inhibition of Cdc42 prevented second polar body emission. Therefore, Cdc42 activation likely promotes membrane protrusion during polar body emission in widespread systems.

Predicting microstructures in polymer blends under two-step quench in two-dimensional space

The formation of nanostructures during two-step quench in binary polymer systems having various types of liquid miscibility gaps are investigated systematically via computer simulations using the phase field method. Coupled liquid spinodal decomposition and fluid flow processes are considered by solving simultaneously the Cahn-Hilliard and Navier-Stokes equations. Various interesting phenomena and morphological patterns are predicted. It is found that the primary microstructures developed at the first quench and isothermal holding temperature greatly affect the secondary microstructures developed during the second quench and isothermal holding. Depending on the morphology and scale of the primary microstructure, either multicore and multishell or unicore and unishell structures are predicted. The breakup of annuluses in a core-shell structure in two dimensions is analyzed. The effects of viscosity on the formation of core-shell structure and on the growth and coarsening behaviors of bimodal droplets produced by the two-step quench in systems are also investigated.

Temperature effects on the band gaps of Lamb waves in a one-dimensional phononic-crystal plate (L)

This study investigates the temperature-tuned band gaps of Lamb waves in a one-dimensional phononic-crystal plate, which is formed by alternating strips of ferroelectric ceramic Ba(0.7)Sr(0.3)TiO(3) and epoxy. The sensitive and continuous temperature-tunability of Lamb wave band gaps is demonstrated using the analyses of the band structures and the transmission spectra. The width and position of Lamb wave band gaps shift prominently with variation of temperature in the range of 26 °C-50 °C. For example, the width of the second band gap increases from 0.066 to 0.111 MHz as the temperature is increased from 26 °C to 50 °C. The strong shift promises that the structure could be suitable for temperature-tuned multi-frequency Lamb wave filters.

Metallic liquids and glasses: atomic order and global packing

In this Letter, we have revealed the common structural behavior of metallic glasses through scrutinizing the evolution of pair distribution functions from metallic liquids to glasses and statistically analyzing pair distribution functions of 64 metallic glasses. It is found that the complex atomic configuration in metallic glasses can be interpreted globally as a combination of the spherical-periodic order and local translational symmetry. The implications of our study suggest that the glass transition could be visualized mainly as a process involving in local translational symmetry increased from the liquid to glassy states.

Effect of waterborne copper exposure on growth, hepatic enzymatic activities and histology in Synechogobius hasta

The present study was conducted to determine growth, hepatic enzymatic activities and histology in Synechogobius hasta exposed to waterborne copper concentrations of 0 (control), 0.15 and 0.3 mg Cu/l, respectively, for 15 days, and explore whether waterborne copper exposure could induce the fatty liver syndrome for the fish species. Growth (WG and SGR) declined, but HSI increased in S. hasta with increasing waterborne copper levels (P<0.05). Waterborne copper exposure also significantly increased lipid content and reduced protein content in both whole body and liver, and increased copper accumulation in whole body and vertebrae. Copper exposure changed hepatic enzymatic activities (SOD, CAT, SDH, PK, LDH, LPL and HL) and increased hepatic lipid peroxidation level, impaired the histological structure of the gill and liver in S. hasta. Thus, our study demonstrated for the first time that waterborne Cu exposure could induce fatty liver syndrome in fish.