Search

Titanium (Ti) and its alloys are known to exhibit room-temperature fracture toughness below 130 MPa m 1/2 , only about one half of the best austenitic stainless steels. It is purported that this is not the best possible fracture resistance of Ti, but a result of oxygen impurities that sensitively retard the activities of plasticity carriers in this hexagonal close-packed metal. By a reduction of oxygen content from the 0.14 wt% in commercial purity Ti to 0.02 wt%, the mode-Ι fracture toughness of the low-oxygen Ti is measured to be as high as K J Ic ≈ 255 MPa m 1/2 , corresponding to J-integral-based crack-initiation toughness of up to J Ic ≈ 537 kJ m -2 . This extraordinary toughness, reported here for the first time for pure Ti, places Ti among the toughest known materials. The intrinsic high fracture resistance is attributed to the profuse plastic deformation in a significantly enlarged plastic zone, rendered by the pronounced deformation twinning ahead of the crack tip along with ample twin-stimulated 〈c+a〉 dislocation activities, in the absence of impeding oxygen. Controlling the content of a property-controlling impurity thus holds the promise to be a readily applicable strategy to reach for unprecedented damage tolerance in some other structural alloys., (© 2024 Wiley‐VCH GmbH.)

Objective: To evaluate the sensitivity of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) puncture to obtain intrathoracic lymph node samples combined with Xpert MTB/RIF (Xpert) detection for the diagnosis of intrathoracic lymph node tuberculosis. Methods: From March 2018 to June 2021, 106 patients [55 males and 51 females, age (45.1±18.6) years] with suspected intrathoracic lymph node tuberculosis and EBUS-TBNA were collected in Zhejiang Hospital of Integrated Traditional Chinese and Western Medicine, including 64 patients with subsequent diagnosis of intrathoracic lymph node tuberculosis and 42 patients without tuberculosis. Xpert test and traditional etiology test were performed on the patients' intrathoracic lymph node puncture specimens. The positive results of different detection methods and different methods were analyzed, and the influencing factors of Xpert independent detection positive were analyzed by univariate and multivariate logistic regression. Results: The sensitivity of Xpert was 65.6% (95% CI : 52.7%-77.1%), the specificity was 97.6% (95% CI : 87.4%-99.9%), the positive predictive value was 97.7% (95% CI : 85.7%-99.7%), the negative predictive value was 65.1% (95% CI : 57.0%-72.4%). The positive rate of Xpert alone (65.6%, 42/64) was not significantly different from that of MGIT960, histopathology and Xpert combined detection (70.3%, 45/64) ( P <0.05). Multivariate logistic regression analysis showed that the location of the diseased lymph nodes in the mediastinum ( OR =5.84, 95% CI : 1.112-30.704, P =0.037), necrosis in the lymph nodes ( OR =6.32, 95% CI : 1.460-27.384, P =0.014), and the axial depth of the lymph nodes≥17 mm ( OR =6.61, 95% CI : 1.408-30.969, P =0.017) were the promoting factors for the positive Xpert test. Conclusions: EBUS-TBNA combined with Xpert detection has a high clinical diagnostic value for intrathoracic lymph node tuberculosis. When the number of puncture samples is small, Xpert detection can be preferred. The positive rate of Xpert detection can be improved by selecting lymph nodes with mediastinal lesions, lymph nodes necrosis, and axial lymph nodes depth≥17 mm for puncture.

Acoustic spectroscopy and neural networks (NNs) are applied to on-line real-time measurement of particle size distribution (PSD) during wet milling of pharmaceutical nanocrystals. A method for modeling the relationship between acoustic attenuation spectra and PSD is proposed that is based on NNs and principal component analysis (PCA). PCA reduces the dimensions of both the spectra and the PSD; then, a neural network model of 2 × 2 × 2 (input, hidden, output layer nodes) with only eight connection weights is built. Compared with previous instrument models that could require as many as 14 physical properties, the current approach does not need any prior knowledge of the system's properties. In addition, the time taken to complete a PSD measurement is reduced from minutes to seconds and it always generates a single solution, rather than possible multiple PSD solutions as in early methods. Application to hydrotalcite nanomilling found good agreement between the on-line measurements and off-line analysis., (© 2023 Acoustical Society of America.)

Objective: To investigate the prognostic factors of cutaneous malignant melanoma (CMM) and establish an effective nomogram survival prediction model., Materials and Methods: The clinical data of patients diagnosed with stage M0 CMM from 2000 to 2019 in the Surveillance, Epidemiology, and End Results (SEER) database were collected and retrospectively analyzed. The variables that may be related to prognosis were analyzed by Lasso-Cox regression analysis using R software. Independent prognostic factors were screened. A nomogram model for predicting the prognosis of CMMC was drawn, and its accuracy was verified by c-index, NR, IDI and calibration curve., Results: A total of 2,679 patients with CMM were included. Lasso-Cox analysis showed that male sex, multiple tumors, higher T stage, SEER stage, widowed, divorced, and separated often indicated poor prognosis. The nomogram model calibration curve was in good agreement with the ideal curve, and the C-index was 0.734 in the training group and 0.761 in the validation group, respectively. In the training group, the AUC of 1-, 3-, 5- and 8-year survival were 0.80, 0.75, 0.74 and 0.72, respectively. In the validation group, the AUC of 1-, 3-, 5- and 8-year survival were 0.75, 0.79, 0.78 and 0.79, respectively. NRI and IDI were superior to the prediction ability of TNM stage and SEER stage (p < 0.05). The established prognostic score can divide patients into high and low score groups with significant prognostic difference (p < 0.05)., Conclusions: Sex, SEER stage, T stage, total number of tumors and marital status are independent prognostic factors for CMM patients, and the nomogram model presented a better performance than TNM stage and SEER stage in predicting the prognosis of CMM patients.

Purpose: Parkinson's disease (PD) is a serious neurodegenerative disease affecting the elderly. In general, the locomotion deficit, which seriously affects the daily life of patients with PD, usually occurs at a later stage. The mask face symptom meanwhile progressively worsens. However, facial muscle disorders and changes involved in the freezing mask are unclear., Method: In this study, we recruited 35 patients with PD and 26 age- and sex-balanced controls to undergo phonation tests, while the built-in camera on the laptop recorded their facial expressions during the whole pronunciation process. Furthermore, FaceReader (version 7.0; Noldus Information Technology, Wageningen, Netherlands) was used to analyze changes in PD facial landmark movement and region movement., Results: The two-tailed Student's t -test showed that the changes in facial landmark movement among 49 landmarks were significantly lower in patients with PD than in the control group ( P < 0.05). The data on facial region movement revealed that the eyes and upper lip of patients with PD differed significantly from those in the control group., Conclusion: Patients with PD had defects in facial landmark movement and regional movement when producing a single syllable, double syllable, and multiple syllables, which may be related to reduced facial expressions in patients with PD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Xu, Zou, Yang, Mo, Guo, Zhang, Weng and Xing.)

Objectives: We compared clinical performance of three strategies of primary human papillomavirus (HPV) testing, primary cytology and co-testing for cervical cancer screening., Design: A population-based prospective cohort study of clinical performance of screening strategy., Setting: Patients recruited from community in Changzhi County, Shanxi Province, China., Patient: 3209 women aged 30-64 years without gynaecological issues., Primary and Secondary Outcome Measures: The performance of different screening strategies for detecting cervical intraepithelial neoplasia grade 2 or more severe (CIN2+)., Results: A total of 53 CIN2+ and 31 CIN3+ cases are detected. For CIN2+, sensitivity of primary HPV (95.9%) and co-testing (98.0%) are not statistically different, but significantly higher than primary cytology (48.0%). Specificity (86.8%), colposcopy referral rate (7.8%) and number of colposcopies required to detect one case (9.8) for primary HPV are better than co-testing (79.8%, 11.9%, 14.3%, respectively). For CIN3+, primary HPV, co-testing have 100% of sensitivity and specificity, which is significantly higher than primary cytology (56.7% and 90.2%). Number of colposcopies required to detect one case for primary HPV (15.9) is better than co-testing (23.8)., Conclusions: Compared with co-testing, HPV primary screening had comparable sensitivity and higher specificity for CIN2+ detection, and both of them showed better performance than cytology primary screening in cervical cancer screening., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumours. PDAC has a poor prognosis; therefore, it is necessary to perform further risk stratification. Identifying prognostic factors before treatment might help to implement suitable and personalised treatment for individuals and avoid side effects. Conventional staging systems and tumour biomarkers are fundamental to establish prognosis; however, they have obvious limitations. Novel imaging biomarkers extracted from advanced imaging techniques offer opportunities to evaluate underlying tumour physiological characteristics, such as mutational status, cellular composition, local microenvironment, tumour metabolism, and biological behaviour. Thus, imaging biomarkers might help the decision making of oncologists and surgeons. The present review discusses the functions of imaging biomarkers for prognostic prediction in patients with PDAC and their potential value for further translation in clinical practice., (Copyright © 2020 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objective: This study aimed to evaluate the effects of in-utero exposure to HIV and ART on pregnancy outcome and early growth of children., Methods: This cohort study enrolled 802 HIV-infected pregnant women between October 2009 and May 2018 in Guangzhou, China. The women were assigned to receive combination ART (cART) or mono/dual ART or no treatment. The primary outcomes were the combined endpoints of any adverse pregnancy outcome [including ectopic pregnancy, spontaneous abortion, stillbirth, preterm birth, small for gestational age (SGA)] and adverse early growth outcome (including infant death, HIV infection of mother-to-child transmission, and underweight, wasting and stunting of infants at 4 weeks of age)., Results: Adverse pregnancy outcomes occurred in 202 (35.1%) of all enrolled HIV-infected women, and 121 (31.3%) of all infants exhibited adverse effects on early growth at 4 weeks of age. The rates of adverse pregnancy outcomes, spontaneous abortion, ectopic pregnancy, stillbirth, infant death and perinatal HIV infection were higher among women not receiving ART, compared to those treated with cART or mono/dual ART (P < 0.05). However, women treated with cART had a higher rate of SGA, compared to untreated women (P < 0.05). No differences in early infant growth were observed among the different treatment regimens., Conclusion: Our findings underscore the essentiality of prioritizing HIV-positive pregnant women for ART, as even mono/dual ART available in resource-limited countries could improve pregnancy outcomes and infant survival.., (Copyright © 2019 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.)

Background: Surgical site infections (SSI) remain a major cause of morbidity after hepatectomy for hepatocellular carcinoma (HCC)., Aim: To identify the risk factors associated with SSI, and develop a nomogram to predict SSI among patients undergoing hepatectomy., Methods: We retrospectively reviewed the data of patients diagnosed with HCC undergoing hepatectomy at two academic institutions in China, and evaluated the occurrence of SSI. Independent risk factors for SSI were identified using univariate and multivariate analyses. Based on these independent risk factors, a nomogram was established using the data of patients in the first institution, and was validated using data from an external independent cohort from the second institution., Results: The nomogram was established using data from 309 patients, whereas the validation cohort used data from 331 patients. The operation duration, serum albumin level, repeat hepatectomy, and ASA score were identified as independent risk factors. The concordance index (C-index) of the nomogram for SSI prediction in the training cohort was 0.86; this nomogram also performed well in the external validation cohort, with a C-index of 0.84. Accordingly, we stratified patients into three groups, with a distinct risk range based on the nomogram prediction, to guide clinical practice., Conclusion: Our novel nomogram offers good preoperative prediction for SSIs in patients undergoing hepatectomy., Competing Interests: Conflict-of-interest statement: All authors declare no conflicts of interest related to this article.

Objective: To evaluate the influence of antiretroviral prophylaxis on the growth and development of HIV-exposed uninfected infants in Guangzhou. Methods: Data were from the national information system for prevention of mother-to-child transmission of HIV infection, syphilis and hepatitis B. After excluding death and perinatal HIV infection cases, 564 HIV-exposed uninfected infants were included. The infants were divided into three groups, nevirapine (NVP) group, zidovudine (AZT) group and untreated group. The influences of antiretroviral prophylaxis on the body weight and height of the HIV-exposed uninfected infants were analyzed by using generalized estimating equations. Results: The HIV-exposed uninfected infants at 1-month old had lower Z scores of body weight-for-age and body height-for-age than the World Health Organization's reference standard. The prevalence of wasting in AZT group (17.5 % ) was higher than that in NVP group (6.2 % ) for 1-month old infants. Taking NVP or AZT was a protective factor for Z score of body length-for-age ( P <0.05). Intrauterine exposure to triple antiviral drugs was a risk factor for the Z scores of body weight-for-age and body length-for-age ( P <0.05). Conclusion: The physical growth and development of HIV-exposed uninfected infants at 1-month old was not well, and HIV-exposed uninfected infants who taking AZT had a higher incidence of wasting. Attention should be paid to these infants.

A new dimeric naphtho- γ -pyrone, asperpyrone F ( 1 ), along with six known ones, asperpyrones B ( 2 ) and C ( 3 ), fonsecinones A ( 4 ) and B ( 5 ), aurasperones A ( 6 ) and E ( 7 ), have been isolated from the solid culture of the edible fungus Pleurotus ostreatus. The structures of 1-7 were determined mainly by NMR and MS experiments. The absolute configuration of compound 1 was assigned via the circular dichroism (CD) data analysis. Compounds 1-7 showed modest antioxidant and immunomodulatory activities. All compounds were isolated from the fungus P. ostreatus for the first time.

With the continuous progress of virtual simulation technology, medical surgery visualization system has been developed from two-dimensional to three-dimensional, from digital to network and intelligentization. The visualization system with mixed reality technology will also be used in all stage of medical surgery, such as case discussion, surgical planning, intraoperative guidance, post-operative evaluation, rehabilitation, so as to further promote high intelligence, high precision of medical surgery, and consequently improve effectiveness of treatment and quality of medical service. This paper discusses the composition and technical characteristics of medical operation visualization system based on mixed reality technology, and introduces some typical applications of mixed reality technology in medical operation visualization, which provides a new perspective for the application of mixed technology in medical surgery.

Urea transporters (UTs) are transmembrane proteins that transport urea molecules across cell membranes and play a crucial role in urea excretion and water balance. Modeling the functional characteristics of UTs helps us understand how their structures accomplish the functions at the atomic level, and facilitates future therapeutic design targeting the UTs. This study was based on the crystal structure of Desulfovibrio vulgaris urea transporter (dvUT). To model the binding behavior of urea molecules in dvUT, we constructed a cooperative binding model. To model the substitution of urea by the urea analogue N,N'-dimethylurea (DMU) in dvUT, we calculated the occupation probability of DMU along the urea pore and the ratio of the occupation probabilities of DMU at the external (S ext ) and internal (S int ) binding sites, and we established the mutual substitution rule for binding and substitution of urea and DMU. Based on these calculations and modelings, together with the use of the Monte Carlo (MC) method, we further modeled the urea flux in dvUT, equilibrium urea binding to dvUT, and the substitution of urea by DMU in the dvUT. Our modeling results are in good agreement with the existing experimental functional data. Furthermore, the modelings have discovered the microscopic process and mechanisms of those functional characteristics. The methods and the results would help our future understanding of the underlying mechanisms of the diseases associated with impaired UT functions and rational drug design for the treatment of these diseases., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Chemical toxicity is an important reason for late-stage failure in drug R&D. However, it is time-consuming and expensive to identify the multiple toxicities of compounds using the traditional experiments. Thus, it is attractive to build an accurate prediction model for the toxicity profile of compounds., Materials and Methods: In this study, we carried out a research on six types of toxicities: (I) Acute Toxicity; (II) Mutagenicity; (III) Tumorigenicity; (IV) Skin and Eye Irritation; (V) Reproductive Effects; (VI) Multiple Dose Effects, using local lazy learning (LLL) method for multi-label learning. 17,120 compounds were split into the training set and the test set as a ratio of 4:1 by using the Kennard-Stone algorithm. Four types of properties, including molecular fingerprints (ECFP&#95;4 and FCFP&#95;4), descriptors, and chemical-chemical-interactions, were adopted for model building., Results: The model 'ECFP&#95;4+LLL' yielded the best performance for the test set, while balanced accuracy (BACC) reached 0.692, 0.691, 0.666, 0.680, 0.631, 0.599 for six types of toxicities, respectively. Furthermore, some essential toxicophores for six types of toxicities were identified by using the Laplacian-modified Bayesian model., Conclusion: The accurate prediction model and the chemical toxicophores can provide some guidance for designing drugs with low toxicity., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Platinum group elements (PGEs) can be naturally found only at very low concentration in the earth crust. However, the increasing usage of PGEs in vehicle exhaust catalysts, and some other applications cause their anthropogenic emission and spread in the environment. Currently，the accumulation of PGEs in the environment has increased over the time. Catalytic converters of modern vehicles are considered to be the main sources of PGE pollution. In order to survey PGEs contamination at residential districts in the urban areas of Beijing City, roadside dust samples were collected. The roadside dust samples were digested with aqua regia and separated and purified with cation exchange resin (Dowex AG50W-X8), and then the resulting solutions were analyzed with inductively coupled plasma mass spectrometry (ICP-MS). PGEs pollution degree in dusts was analyzed using Geoaccumulation Index. The results showed that the concentrations of Pd, Pt and Rh in roadside dusts ranged from 14.20～161.80 ng·g-1 (50.76 ng·g-1), 9.39～70.80 ng·g-1(23.82 ng·g-1), 3.18～17.05 ng·g-1(7.54 ng·g-1), respectively. It indicated that concentrations of PGEs in dusts of residential areas were obviously higher than those values in Beijing soil background. The results of Geoaccumulation Index assessment indicated that the roadside dusts in residential areas were obviously polluted by the PGEs in Beijing city. The order of average pollution level of the PGEs is: Pd＞Pt＞Rh.

The mer operon confers bacterial resistance to inorganic mercury (Hg(2+)) and organomercurials by encoding proteins involved in sensing, transport and detoxification of these cytotoxic agents. Expression of the mer operon is under tight control by the dual-function transcriptional regulator MerR. The metal-free, apo MerR binds to the mer operator/promoter region as a repressor to block transcription initiation, but is converted into an activator upon Hg(2+)-binding. To understand how MerR interacts with Hg(2+) and how Hg(2+)-binding modulates MerR function, we report here the crystal structures of apo and Hg(2+)-bound MerR from Bacillus megaterium, corresponding respectively to the repressor and activator conformation of MerR. To our knowledge, the apo-MerR structure represents the first visualization of a MerR family member in its intact and inducer-free form. And the Hg(2+)-MerR structure offers the first view of a triligated Hg(2+)-thiolate center in a metalloprotein, confirming that MerR binds Hg(2+) via trigonal planar coordination geometry. Structural comparison revealed the conformational transition of MerR is coupled to the assembly/disassembly of a buried Hg(2+) binding site, thereby providing a structural basis for the Hg(2+)-mediated functional switching of MerR. The pronounced Hg(2+)-induced repositioning of the MerR DNA-binding domains suggests a plausible mechanism for the transcriptional regulation of the mer operon., (© The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Urea transporters are a family of membrane proteins that transport urea molecules across cell membranes and play important roles in a variety of physiological processes. Although the crystal structure of bacterial urea channel dvUT has been solved, there lacks an understanding of the dynamics of urea transport in dvUT. In this study, by using molecular dynamics simulations, Monte Carlo methods, and the adaptive biasing force approach, we built the equilibrium structure of dvUT, calculated the variation in the free energy of urea, determined the urea-binding sites of dvUT, gained insight into the microscopic process of urea transport, and studied the water permeability in dvUT including the analysis of a water chain in the pore. The strategy used in this work can be applied to studying transport behaviors of other membrane proteins.

Fibroblastic rheumatism (FR) is a rare condition characterized by symmetrical polyarthritis and multiple cutaneous nodules. Approximately 30 cases have been reported worldwide to date. Laboratory tests are not particular useful to confirm the disease. Diagnosis is mainly dependent on the characteristic histopathological features: thickened collagen fibres with spindle-shaped cell proliferation in the skin lesion. We report a case of a 48-year-old Chinese man with typical clinical features of FR. In addition to the characteristic histopathological findings, multinuclear giant cell infiltration in skin lesions was detected, in this case. The evaluation of microelements revealed a raised blood lead level) of 129 μg/L (normal range 0-99 μg/L) These two features have never been described in the previous medical literature on FR. Thus, we propose that examining the infiltrated cells in detail in histopathological studies and inspecting the levels of lead and other microelements in the blood may increase our understanding of the pathogenesis of FR., (© 2014 British Association of Dermatologists.)

The present study was designed to isolate the polyphenol constituents of cultured cells of Saussurea involucrata. The polyphenol type constituents were isolated using chromatography methods, and then characterized by spectral analysis. 1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl)-hydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radical scavenging were assayed using Vitamin C as the positive control. One new polyphenol 18, 1, 3-di-O-caffeoyl-5-O-(1-methoxyl-2-O-caffeoyl-4-maloyl)-quinic acid, together with 17 known compounds, was isolated and characterized. In conclusion, Compound 18 was a new caffeoyl maloyl quinic acid type polyphenol and showed desired vitro anti-oxidant activity. Compounds 1-5, 9, 10, 14, 15, and 17 were isolated from cultured cells of Saussurea involucrata for the first time., (Copyright © 2015 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.)

In biological systems, methylation is most commonly performed by methyltransferases (MTs) using the electrophilic methyl source S-adenosyl-L-methionine (SAM) via the S(N)2 mechanism. (2S,3S)-β-Methylphenylalanine, a nonproteinogenic amino acid, is a building unit of the glycopeptide antibiotic mannopeptimycin. The gene product of mppJ from the mannopeptimycin-biosynthetic gene cluster is the MT that methylates the benzylic C atom of phenylpyruvate (Ppy) to give βMePpy. Although the benzylic C atom of Ppy is acidic, how its nucleophilicity is further enhanced to become an acceptor for C-methylation has not conclusively been determined. Here, a structural approach is used to address the mechanism of MppJ and to engineer it for new functions. The purified MppJ displays a turquoise colour, implying the presence of a metal ion. The crystal structures reveal MppJ to be the first ferric ion SAM-dependent MT. An additional four structures of binary and ternary complexes illustrate the molecular mechanism for the metal ion-dependent methyltransfer reaction. Overall, MppJ has a nonhaem iron centre that bind, orients and activates the α-ketoacid substrate and has developed a sandwiched bi-water device to avoid the formation of the unwanted reactive oxo-iron(IV) species during the C-methylation reaction. This discovery further prompted the conversion of the MT into a structurally/functionally unrelated new enzyme. Through stepwise mutagenesis and manipulation of coordination chemistry, MppJ was engineered to perform both Lewis acid-assisted hydration and/or O-methyltransfer reactions to give stereospecific new compounds. This process was validated by six crystal structures. The results reported in this study will facilitate the development and design of new biocatalysts for difficult-to-synthesize biochemicals.

The six heavy metal concentrations (Cr, Cr, As, Cd, Cu, Zn and Pb) in water samples collected from five reservoirs of Liao River Basin were studied. The health risk assessment for heavy metals pollution in reservoirs was conducted based on the environmental health risk assessment model recommended by U. S. Environmental Protection Agency. The results showed that the average concentrations of Cr, Cu, Zn, As, Cd and Pb in five reservoirs of Liao River Basin were 3.36, 1.03, 2. 70, 1.23, 0. 02 and 0. 03 microg L-1, respectively. In fact, these heavy metals concentrations were obviously lower than the Standard of National Drinking Water in China (GB 5749-2006). The results also showed that the metal carcinogenic risk was relatively high in this region. The order of the risk level of carcinogenic metals was Cr>As>Cd. The highest carcinogenic risk was from Cr, with the risk for adults ranging from 4. 50 X 10(-5) approximately 7. 53 X 10(-5) a-1' and the risk for children ranging from 6. 29 X 10(-5) to 1. 05 X 10(-4) a-1. The health risk levels caused by non-carcinogenic metals ranging from 10-13 to 10(-10) a-1 were lower than the acceptable range suggested by International Commission on Radiological Protection (ICRP) and the order of the risk level of non-carcinogenic metals was Cu>Zn>Pb. The total health risk of heavy metals for adults ranging from 1. 07X 10(-4) to 1. 72X 10(-4) a-1 and for children ranging from 1. 49 X 10(-4) to 2. 40 X 10(-4) a-1 exceeded the accepted level of 5 X 10(-5) a-1 as suggested by ICRP. The health risk levels of carcinogenic metals were significantly higher than those of non-carcinogenic metals in the reservoirs for Liao River Basin.

Mutations in ClC channel proteins may cause serious functional changes and even diseases. The function of ClC proteins mainly manifests as Cl(-) transport, which is related to the binding free energies of chloride ions. Therefore, the influence of a mutation on ClC function can be studied by investigating the mutational effect on the binding free energies of chloride ions. The present study provides quantitative and systematic investigations on the influences of residue mutations on the electrostatic binding free energies in Escherichia coli ClC (EcClC) proteins, using all-atom molecular dynamics simulations. It was found that the change of the electrostatic binding free energy decreases linearly with the increase of the residue-chloride ion distance for a mutation. This work reveals how changes in the charge of a mutated residue and in the distance between the mutated residue and the binding site govern the variations in the electrostatic binding free energies and therefore influence the transport of chloride ions and conduction in EcClC. This work would facilitate our understanding of the mutational effects on transport of chloride ions and functions of ClC proteins and provide a guideline to estimate which residue mutations will have great influences on ClC functions.

A three-state, multiion kinetic model was proposed to enable the conduction properties of the mammalian channel ClC-0 to be well characterized. Using this rate-theory based model, the current-voltage and conductance-concentration relations were obtained. The five parameters needed were determined by fitting the data of conduction experiments of the wild-type ClC-0 and its K519C mutant. The model was then tested against available calculation and simulation data, and the energy differences between distinct chloride-occupancy states computed agreed with an independent calculation on the binding free energies solved by using the Poisson-Boltzmann equation. The average ion number of conduction and the ion passing duration calculated closely resembled the values obtained from Brownian dynamics simulations. According to the model, the decrease of conductance caused by mutating residue K519 to C519 can be attributed to the effect of K519C mutation on translocation rate constants. Our study sets up a theoretical model for ion permeation and conductance in ClC-0. It provides a starting point for experimentalists to test the three-state model, and would help in understanding the conduction mechanism of ClC-0., (Copyright (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Solvolysis is one of the important processes of biomass liquefaction. To produce superior quality liquid biofuel from biomass under mild conditions, it is essential to exploit novel reactive liquid solvent. Furthermore, the evaluation of liquefaction efficiency is carried out mainly by the means of analysis of the products derived from biomass liquefaction. In the present study, liquefaction of poplar wood powder in acidified 1-octanol was investigated with a stainless steel autoclave. Residue, heavy oil and light oil were separated from the liquefaction products by extraction with acetone and n-hexane successively. FTIR analysis was carried out on these liquefaction compositions to illuminate the liquefaction regularities and mechanisms of cellulose, hemicellulose and lignin of wood. The results showed that liquefaction oils were complex mixture containing hydroxide, carbonyl, methoxyl, aromatic and aether. Liquefactions of cellulose and hemicellulose were easier than that of lignin. Cellulose and hemicellulose were converted to light oil, however, lignin was mainly converted to heavy oil. At 150 degrees C, lignin was depolymerized and degraded into micromolecular aromatic compounds, among which condensation reactions took place when reaction temperature increased.

An increasing attention has been dedicated to the characterization of complex networks within the protein world. Before now most investigations about protein structures were only considered where the interactive cutoff distance R(c)=5 or 7A. It is noteworthy that the length of peptide bond is about 1.5A, the length of hydrogen bond is about 3A, the range of London-van der Waals force is about 5A and the range of hydrophobic effect can reach to 12A in protein molecule. Present work reports a study on the topological properties of the amino acid network constructed by different interactions above. The results indicate that the small-world property of amino acid network constructed by the peptide and hydrogen bond, London-van der Waals force and the hydrophobic effect is strong, very strong and relatively weak, respectively. Besides, there exists a precise exponential relation C is proportional to k(-0.5) at R(c)=12A. It means that the amino acid network constructed by the hydrophobic effect tend to be hierarchical. Functional modules could be the cause for hierarchical modularity architecture in protein structures. This study on amino acid interactive network for different interactions facilitates the identification of binding sites which is strongly linked with protein function, and furthermore provides reasonable understanding of the underlying laws of evolution in genomics and proteomics.

Two types of alternating morphology transitions have been observed in crystallization of NH4Cl on agar plates. One is the alternating morphology transitions between dense branching morphology and sparse branching morphology, and the other is the alternating morphology transitions between dense branching morphology and zigzag branching morphology. The appearance of them is found to depend on the mass proportion of agar to NH4Cl in the initial solution and the relative humidity. It is suggested that both the two alternating morphology transitions result from the oscillation of solute concentration in front of the growing interface caused by the competition of crystal growth and solute transfer at a moderate mass proportion. Which one of them occurs depends on the relative humidity, which controls the supersaturation.

We demonstrate highly efficient avalanche multiphoton luminescence (MPL) from ordered-arrayed gold nanowires (NWs) with low time-average excitation intensity, Iexc (5.0-9.1 kW/cm2). The intensity of avalanche MPL, IMPL, is about 10(4) times larger than that of three-photon luminescence, the slope partial differential log IMPL/ partial differential log Iexc of avalanche MPL reaches as high as 18.3, and the corresponding polarization dependence of IMPL has a form of cos50 phip. The emission dynamics of avalanche MPL and three-photon luminescence are also studied comparatively. These observations indicate that the highly efficient avalanche MPL is attributed to the giant enhancement and coupling of longitudinal surface plasmon resonance of ordered-arrayed gold NWs.

To describe the aggregation behaviors on substrates with long-range jump paths, a model of particle-cluster aggregation on a two-dimensional small-world network is presented. This model is characterized by two parameters: the clustering exponent alpha and the long-range connection rate phi. The results show that there exists an asymptotic fractal dimension D(max)(f) that depends upon alpha. With decrement of alpha, D(max)(f) varies from 1.7 to 2.0, which corresponds to a crossover from diffusion-limited-aggregation-like to dense growth. The change of the aggregation pattern results from the long-range connection in the network, which reduces the effect of screening during the aggregation. When the system size is not large enough, the effective fractal dimension D(f) depends upon phi because of the finite-size effect. With primitive analysis, we obtain the expression of the effective fractal dimension D(f) with the network parameters alpha and phi.

Morphological evolution in the electrodeposition of Pb-Sn binary system is studied. As the second component increases, the morphology of the codeposit changes from dendrite to ramification, to dense branch, and finally to fractal structure, respectively. The evolution arises from the influence of crystallographic texture, which leads to a splitting of dendritic tips and the formation of ramified morphology. This work provides direct evidence to explore the crystallographic influence on the morphological evolution in electrodeposition.

Some dynamical processes in a small-world network shows a critical transition at a finite disorder phi(c) of the network, in contrast with the geometrical properties that exhibit the critical behavior at phi(c)=0. Although it has been pointed out in previous works that the transition is related to the structural properties of the network, it is still not very clear why the transition occurs at phi(c) not equal 0. In this paper we present a simple social model of efficiency dynamics in small-world networks, which also shows a transition at phi(c)>0. We obtain the critical point with phi(c) approximately equal 0.098 from the finite-size analysis. It is found that both the geometrical properties of the network and the specific dynamical characters of the model contribute to the critical transition. This work is useful for understanding this kind of transition occurring in many dynamical processes in small-world networks.

A cellular automation model of the "game of Life" on a two-dimensional small-world network is presented in order to count in long-range interactions among living individuals in social or biological systems. The density of the life and its fluctuation are calculated, respectively. The present model exhibits a nonequilibrium phase transition from an "inactive-sparse" state to an "active-dense" one at a certain intermediate value of the network disorder. Employing finite-size scaling analysis, we estimate the location of the critical point with p(c)( infinity ) approximately 0.3685. The transition is of the "second-order" type with power-law diverging length. We obtain the critical exponents 1/nu approximately 1.70, beta approximately 0.50, and beta/nu approximately 0.85. The calculated results indicate that the present model may belong to the universality class of directed percolation.

Multiparticle random walks on a deformable medium have been investigated in (2+1) dimensions. The time evolution of the particle distribution is studied. The results show that the randomly distributed particles in the beginning will be self-organized into a cluster pattern in the intermediate stage, and then return to the random distribution pattern in the late stage. The dependence of the clustering degree on the stiffness parameter of medium alpha, stability parameter of systems beta, and average particle density rho(0) is also investigated. There exists an optimal clustering stability beta(p), at which the system has the strongest clustering ability and corresponds to a maximum clustering coefficient Gamma(*)(p). The dependence of the optimal clustering coefficient Gamma(*)(p) on the stiffness alpha and particle density rho(0) is obtained, and the landscape of the medium generated by particles is also investigated.

The effects of the solvent-surfactant interaction, chain length and stiffness of surfactants on the formation of aggregates and the aggregation degree of surfactants in the two-dimension solution have been investigated using discontinuous molecular-dynamics simulations. When the tail-water repulsion increases or the head-water attraction decreases, the aggregation degree increases. Increasing the chain length and raising the stiffness of surfactants lead to the increment of the aggregation degree.

We investigate the pattern of particle distribution and its evolution with time in multiparticle systems using the model of random walks with memory enhancement and decay. This model describes some biological intelligent walks. With decrease in the memory decay exponent alpha, the distribution of particles changes from a random dispersive pattern to a locally dense one, and then returns to the random one. Correspondingly, the fractal dimension D(f,p) characterizing the distribution of particle positions increases from a low value to a maximum and then decreases to the low one again. This is determined by the degree of overlap of regions consisting of sites with remanent information. The second moment of the density rho(2) was introduced to investigate the inhomogeneity of the particle distribution. The dependence of rho(2) on alpha is similar to that of D(f,p) on alpha. rho(2) increases with time as a power law in the process of adjusting the particle distribution, and then rho(2) tends to a stable equilibrium value.

The investigation on diffusion with directed motion in a two-dimensional continuous space is completed by using the model of the continuous directed random walks. The average square end-to-end distance approximately t(2nu) is calculated. The results show that this type of walks belongs asymptotically to the same class (nu=1.0) as the ballistic motions. For short time, we observe a crossover from purely random walks (nu=0.5) to ballistic motions (nu=1.0). The dependence of the crossover on the direction parameter theta is studied. There exists a scaling relation of the form approximately tf(t/theta(-2)). The return probability P00(t) is also investigated and the scaling form similar to is obtained.

The pattern formation on nonuniform surfaces by correlated-random sequential absorption (CRSA) process has been investigated by computer simulations. The nonuniform surfaces are represented by percolation clusters with probabilities p(s) and p(s) stands for the nonuniform degree of surfaces. The interactions between the particles and the defects in surfaces are involved by introducing a sticking coefficient s. When s-->0, the CRSA process is controlled by the absorption of surfaces and the correlation between particles. With the correlation increasing from a weak limit to a strong one, the cluster consisting of absorbed particles changes from the dispersed pattern of site percolation to correlated percolation, and then to Leath percolation clusters. When s-->1 and p(s)-->p(c), the CRSA process is dominated by the absorption of the defects, where p(c) is the threshold of percolations. The patterns appear randomly dispersed in spite of the correlation. With the decrease of s and increase of p(s), the interaction controlling the CRSA process changes from the absorption of defects to that of surface and the correlation between particles gradually. For the system s-->0, the transition correlation exponent alpha(c)=d(s), where d(s) is the fractal dimension of the percolation surfaces.

A model of random walk with memory enhancement and decay was presented on the basis of the characteristics of the biological intelligent walks. In this model, the movement of the walker is determined by the difference between the remaining information at the jumping-out site and jumping-in site. The amount of the memory information s(i)(t) at a site i is enhanced with the increment of visiting times to that site, and decays with time t by the rate e(-beta(t)), where beta is the memory decay exponent. When beta=0, there exists a transition from Brownian motion (BM) to the compact growth of walking trajectory with the density of information energy u increasing. But for beta>0, this transition does not appear and the walk with memory enhancement and decay can be considered as the BM of the mass center of the cluster composed of remembered sites in the late stage.

A model of random walks on a deformable medium is proposed in 2+1 dimensions. The behavior of the walk is characterized by the stability parameter beta and the stiffness exponent alpha. The average square end-to-end distance l approximately equals (2nu) and the average number of visited sites approximately equals (k) are calculated. As beta increases, for each alpha there exists a critical transition point beta(c) from purely random walks ( nu = 1/2 and k approximate to 1) to compact growth ( nu = 1/3 and k = 2/3). The relationship between beta(c) and alpha can be expressed as beta(c) = e(alpha). The landscape generated by a walk is also investigated by means of the visit-number distribution N(n)(beta). There exists a scaling relationship of the form N(n)(beta)approximately n(-2)f(n/beta(z)).

A percolation model with long-range correlations was introduced to investigate the phenomena of epidemic spreading by Monte Carlo simulations. The correlation exponent alpha and pathogenic ratio s correspond to different spreading methods and pathogenicity of variant epidemics. As the correlation changes from a weak one to a strong one, the patterns change from site percolation to Eden cluster when pathogenic ratio s=1, or Leath percolation cluster when s<1. Corresponding to change of patterns, the fractal dimension increases up to space dimension. The critical behavior in epidemic spreading has been examined based on the model. It is found that correlation has a great influence on the threshold of spreading percolation.

The structure transition in cluster-cluster aggregation (CCA) under different external electric fields has been investigated by computer simulations. The aggregates are generated from off-lattice CCA models involving the field-induced dipolar interactions and temperatures by means of a Metropolis algorithm. When the parameter K increases from 0 to infinity, the clusters gradually change from a diffusion-limited CCA to a chainlike pattern, where K stands for the relative strength of the field-induced dipolar interaction with thermal energy. The relation of fractal dimension D(f) to parameter K can be approximately expressed as D(f)=D(E)+(D(DLCA)-D(E))e(-betaK) with beta=0.64, where D(E) and D(DLCA) stand for the fractal dimensions of the CCA when K-->infinity and K-->0, respectively. This structure transition is a transition between a prototype disorder structure and a relative order one. The transition is attributed to the variation of the dominating interaction of systems from thermal disorder to field-induced dipolar interaction with K rising.

The influence of particle size on diffusion-limited aggregation (DLA) has been investigated by computer simulations. For DLA clusters consisting of two kinds of particles with different sizes, when large particles are in the minority, the patterns of clusters appear asymmetrical and nonuniform, and their fractal dimensions D(f) increase compared with one-component DLA. With increasing size of large particles, D(f) increases. This increase can be attributed to two reasons: one is that large particles become new growth centers; the other is the big masses of large particles. As the concentration ratio x(n) of large particles increases, D(f) will reach a maximum value D(f(m)) and then decrease. When x(n) exceeds a certain value, the morphology and D(f) of the two-component DLA clusters are similar to those of one-component DLA clusters.