Vapor-Liquid-Solid Growth of Site-Controlled Monolayer MoS2 Films Via Pressure-Induc ed Supercritical Phase Nucleation.

In this study, a novel pressure-induced supercritical phase nucleation method is proposed to synthesize monolayer MoS2 films, which is promoter free and can avoid contamination of films derived from these heterogeneous promoters in most of the existing techniques. The low-crystallinity and size-controlled MoO2(acac)2 particles are recrystallized on the substrate via the pressure-sensitive solvent capacity of supercritical CO2 and these particles are used as growth sites. The size of single-crystal MoS2 on the substrate is found to be dependent on the wetting area of the pyrolyzed precursor droplets (MoO2) on the surface, and the formation of continuous films with high coverage is mainly controlled by the coalescence of MoO2 droplets. It is enhanced by the increase of the nucleation site density, which can be adjusted by the supersaturation of the supercritical fluid solution. Our findings pave a new way for the controllable growth of MoS2 and other two-dimensional materials and provide sufficient and valuable evidence for vapor-liquid-solid growth.

Microscopic properties and stabilization mechanism of a supercritical carbon dioxide microemulsion with extremely high water content.

HYPOTHESIS: Developing the supercritical carbon dioxide microemulsion with a broad water content (W0) window can provide more possibility for designing highly efficient chemical processes, which is challenging due to the lack of comprehension about its formation mechanism. Molecular dynamics simulation method is expected to reveal the microscopic stabilization mechanism of high-W0 microemulsions. SIMULATIONS: All-atom molecular dynamics simulations of the ternary systems with varied W0 stabilized by 4FG(EO)2 surfactant were designed according to phase behavior experiments. A systematic investigation was performed concerning the self-assembling, equilibrium morphology and detailed microstructure of the microemulsion droplet. An in-depth comparative study about the distribution of both H2O and CO2, the interfacial behaviors of 4FG(EO)2, as well as the microscopic interactions was conducted. FINDINGS: For the first time, direct evidence was provided for the formation of water-in-carbon dioxide microemulsion with extremely high W0 (80) under the effect of 4FG(EO)2. Furthermore, a unique interfacial phenomenon, i. e. CO2 accumulating at the interface, was revealed to be responsible for the formation and enhanced stability of the nanosized droplet with high W0. This should set a new guiding star for synthesizing and selecting effective interfacial modifiers to create high-W0 microemulsions.

The production of graphene using impinging jet exfoliation in a binary system of CO2 and N-methyl pyrrolidone.

High quality and high quantity few-layer graphene was successfully prepared using a new impinging jet method. Natural graphite flakes were first agitated in N-methyl pyrrolidone (NMP) with the assistance of supercritical CO2, then the half-exfoliated graphite was further stripped using the shear stress derived from the impinging jets. After the energy conversion and stress analysis of the graphite particles during the whole exfoliation process, it was revealed that the size of the target mesh, the distance between the nozzle and the target, the decompression rate, and the size of the raw materials had a significant influence on the exfoliation process. Additionally, a microscopic view of the exfoliation and dispersion mechanism of graphene in the CO2-NMP system was investigated using molecular dynamics simulation, and CO2 was found to be beneficial for the penetration of NMP into the graphite sheets. Finally, the concentration and quality characteristics of the prepared graphene were characterized using ultraviolet-visible spectroscopy, transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. The maximum concentration was as high as 0.689 mg ml-1, the thickness of 68% of the product was less than 2.5 nm, and the lateral dimension was from 0.5 to 3.0 µm. These results indicate that this impinging jet method is promising for large-scale industrial production.

Melatonin attenuates nicotine-induced autophagy and neurological changes by decreasing the production of reactive oxygen species.

Purpose: The aim of this study was to explore the mechanism of neurological changes underlying the toxicity of nicotine.Materials and methods: Rat pheochromocytoma 12 (PC12) cells and human neuroglia (HM) cells were used. The ROS levels of the cells were detected by the FACScan. Autophagy flux was monitored by a tandem monomeric RFP-GFP-tagged LC3 lentivirus. The autophagic proteins LC3, SQSTM1/p62 and Beclin1 were detected by western blot assay. In order to evaluate the effects of nicotine and melatonin on the morphological changes of neurons, primary cortical neurons were obtained and immunocytochemistry of TUBB3 tubulin were conducted.Results: Nicotine increased the levels of reactive oxygen species (ROS) in PC12 and HM cells in a concentration-dependent manner. Microscopy showed increased autophagic flux in nicotine-treated PC12 cells. Subsequent western blotting results showed that nicotine induced increase in the levels of LC3B-II and Beclin1, and decreased SQSTM1/p62 in a concentration-dependent manner. Finally, nicotine treatment reduced the length of TUBB3-positive axons and dendrites. Melatonin, a mitochondrially targeted antioxidant, reduced the ROS level, and blocked autophagy activation and the morphologic structural changes induced by nicotine.Conclusions: Our results suggested that the role of nicotine in neuronal toxicity maybe through the induction of ROS and the subsequent activation of autophagy. These effects could be restored by melatonin.

Pretreatment of corn cob in [EMIM][OAc] and [EMIM][OAc]/ethanol (water).

High cost and high viscosity of ionic liquid restricted its commercial application in pretreatment of lignocellulose. Water and ethanol were used as additive in [EMIM][OAc] to pretreat corn cob at moderate temperature (< 100 °C). It was found that enzyme hydrolysis (EH) sugar yield was increased with the increase of IL content. The largest EH sugar yield of 68.8% was obtained when pure IL was used. However, for [EMIM][OAc]/ethanol, the EH sugar yield as high as 66.9% was gained when the IL content was 80%, which was comparable to that for pure IL pretreatment. In addition, Kamlet-Taft parameter was calculated to characterize the polarity solvency of binary liquid phase, to illustrate the underlying reason for the increase of EH sugar and the lignin removal. Finally, to demonstrate the crystalline and microstructure change after pretreatment, XRD and SEM were performed for the raw materials and the pretreated samples.

Process enhancement of supercritical methanol biodiesel production by packing beds.

Continuous fixed bed reactors filled by three kinds of packing which were glass bead, glass spring and Dixon rings were investigated. The effect of temperature, pressure, the molar ratio of methanol to oil, flow rate, the size and shape of the packing were researched. The highest yield 90.84% of FAME was obtained by filling Dixon rings as packing with the condition of the temperature was 350°C, the pressure was 22MPa, the molar ratio of methanol to oil was 42:1. In addition, the reusability of Dixon rings was perfect. Numerical simulation was researched to provide theoretical basis for experimental results, besides the kinetics and thermodynamics behavior were investigated to explore the reaction mechanism.

Evaluation of renal allografts function early after transplantation using intravoxel incoherent motion and arterial spin labeling MRI.

PURPOSE: To evaluate renal allografts function early after transplantation using intravoxel incoherent motion (IVIM) and arterial spin labeling (ASL) MRI. METHODS: This prospective study was approved by the local ethics committee, and written informed consent was obtained from all participants. A total of 82 participants with 62 renal allograft recipients (2-4weeks after kidney transplantation) and 20 volunteers were enrolled to be scanned using IVIM and ASL MRI on a 3.0T MR scanner. Recipients were divided into two groups with either normal or impaired function according to the estimated glomerular filtration rate (eGFR) with a threshold of 60ml/min/1.73m(2). The apparent diffusion coefficient (ADC) of pure diffusion (ADCslow), the ADC of pseudodiffusion (ADCfast), perfusion fraction (PF), and renal blood flow (RBF) of cortex were compared among three groups. The correlation of ADCslow, ADCfast, PF and RBF with eGFR was evaluated. The receiver operating characteristic (ROC) curve and binary logistic regression analyses were performed to assess the diagnostic efficiency of using IVIM and ASL parameters to discriminate allografts with impaired function from normal function. P<0.05 was considered statistically significant. RESULTS: In allografts with normal function, no significant difference of mean cortical ADCslow, ADCfast, and PF was found compared with healthy controls (P>0.05). Cortical RBF in allografts with normal function was statistically lower than that of healthy controls (P<0.001). Mean cortical ADCslow, ADCfast, PF and RBF were lower for allografts with impaired function than that with normal function (P<0.05). Mean cortical ADCslow, ADCfast, PF and RBF showed a positive correlation with eGFR (all P<0.01) for recipients. The combination of IVIM and ASL MRI showed a higher area under the ROC curve (AUC) (0.865) than that of ASL MRI alone (P=0.02). CONCLUSION: Combined IVIM and ASL MRI can better evaluate the diffusion and perfusion properties for allografts early after kidney transplantation.

Assessment of the Cadmium Exposure in the Blood, Diet, and Water of the Pumi People in Yunnan, China.

Cadmium (Cd) is considered as one of the most toxic and carcinogenic heavy metals. Accumulation of Cd in the human body can cause multiorgan dysfunction. Long-term irrational mining activities have led to serious Cd pollution in soil, water, and even agricultural products. Therefore, evaluating the Cd exposure levels of people living in mining areas is of great importance. In the current study, we chose the Pumi people who lived in Jinding and Tongdian towns of Lanping county in Yunnan province, China, to do the on-site nutritional epidemiology investigation and laboratory detection. We analyzed the content of the Cd in peripheral blood and mixed dietary, as well as water samples in the Pumi residents of the two towns. Results showed that the blood Cd levels of people in Jinding town, which is nearer the mining district, were statistically significantly higher than those in Tongdian town. The P 50 of blood Cd level of the two towns was 0.64 ng/mL. In addition, the P 50 of the mixed diet of the two towns was 8.32 µg/kg. There was a weak correlation between blood Cd levels and Cd exposure in the mixed diet, PTDI, and PTWI of the Pumi people. In addition, higher concentrations of Cd were observed in the water of Jinding town, indicating people in Jinding town risking more Cd exposure. These results indicated that diet and water are critical factors of Cd exposure for the residents and the nearer people living to mining district risking the more Cd exposure.

Background rhythm frequency and theta power of quantitative EEG analysis: predictive biomarkers for cognitive impairment post-cerebral infarcts.

In clinical settings, cerebral infarct is a common disease of older adults, which usually increases the risk of cognitive impairment. This study aims to assess the quantitative electroencephalography (qEEG) as a predictive biomarker for the development of cognitive impairment, post-cerebral infarcts, in subjects from the Department of Neurology. They underwent biennial EEG recording. Cerebral infarct subjects, with follow-up cognitive evaluation, were analyzed for qEEG measures of background rhythm frequency (BRF) and relative δ, θ, α, and ß band power. The relationship between cognitive impairment and qEEG, and other possible predictors, was assessed by Cox regression. The results showed that the risk hazard of developing cognitive impairment was 14 times higher for those with low BRF than for those with high BRF (P < .001). Hazard ratio (HR) was also significant for more than median θ band power (HR = 5, P = .002) compared with less than median θ band power. The HRs for δ, α, and ß bands were equal to the baseline demographic, and clinical characteristics were not significantly different. In conclusion, qEEG measures of BRF, and relative power in θ band, are potential predictive biomarkers for cognitive impairment in patients with cerebral infarcts. These biomarkers might be valuable in early prediction of cognitive impairment in patients with cerebral infarcts.

[Treatment with antibiotics for uncomplicated acute appendicitis: strategy and its value].

OBJECTIVE: To establish the characteristics of uncomplicated acute appendicitis (UAA) and assess the efficacy of antibiotics by comparison with emergency appendicectomy for treatment. METHODS: A retrospective clinical analysis was made on 742 cases of acute appendicitis. Several characteristics of UAA were identified. Following these rules 46 UAA patients were enrolled to receive antibiotic treatment for at least 48 h.follow-up was carried out for 6 months. RESULTS: Statistical analysis indicated that high level white blood cell count (>20×10(9)/L,P=0.000, OR=2.717), local or diffuse muscle guarding (P=0.031, OR=1.649), intraluminal stercolith (P=0.000, OR=2.939) and periappendiceal fluid (P=0.005, OR=3.273) were independent risk factors of complicated acute appendicitis. With none of these factors we enrolled 46 UAA patients. Of the 46 patients, 44(95.65%) were treated successfully with antibiotics. 2(4.35%) patients were unexpectedly identified to have complicated appendicitis at surgery. Recurrent appendicitis occurred in 5(11.36%) patients after 6 months. There was no difference in duration of pain and duration of hospital stay between antibiotic treatment group and appendicectomy group. CONCLUSION: Although antibiotic treatment may fail in some UAA cases, and there is a risk of recurrence, antibiotic treatment still appears to be a safe first-line therapy for UAA patients.

Assessment of the iodine status of the Wa national boarding school students in Southwest China.

Iodine deficiency disorder (IDD) has been recognized as a major public health problem worldwide and has serious detrimental effects on the growth and development of the children. Therefore, monitoring the iodine status of the school-aged children is of great importance. We randomly recruited 159 boarding school students (aged from 6 to 14) from 10 primary schools in Lincang County, Yunnan Province. The dietary iodine level of the students was measured by the new mixed meal method and chemical analysis. Fifty-seven daily water samples and 32 salt samples were collected from the same surveyed area to determine the iodine content using the sulfate cerium catalytic spectrophotometric method and the hyposulphite quantitative titration method, respectively. The iodine level of each water sample was ranged from 0.611 to 1.473 µg/L. The median and the mean value of the iodine content in water were 0.972 and 0.979 ± 0.189 µg/L. The average iodine intake of each age group was higher that the recommended nutrient intakes (RNI) but lower than the tolerable upper intake level (UL). The median and the mean value of the iodine content in salt were 25.53 and 25.62 ± 1.70 mg/kg. Taken together, the present study investigated the iodine intake status of Wa school-aged children through examination of their dietary iodine intake, the environment, and the salt iodine status. Results showed that the status of the iodine uptake of the Wa children were higher than the RNI, but lower than the UL.

[Preparation and identification of a recombinant hepatitis C virus (HCV) based on sindbis virus vector].

OBJECTIVE: To construct the recombinant virus-like particles containing HCV envelope glycoprotein E1E2 based on sindbis virus vector. METHODS: The gene encoding HCV envelope glycoprotein E1E2 was cloned into sindbis virus vector to construct recombinant plasmids pBR-XJE1E2 and pVA-XJE1E2, and transfect them into BHK-21 cells to obtain recombinant virus-like particles. The expression of E1 and E2 protein were verified by Western Blot and indirect immunofluorescent assay (IFA). RESULTS: The results of restriction enzyme digestion, PCR and sequencing analysis showed that the recombinant plasmids were constructed successfully. And the results of RT-PCR, Western blotting and IFA detection showed that the transfect cells could package HCV-like particles of expressing structural proteins E1E2. CONCLUSION: The recombinant expression plasmids pBR-XJE1E2 and pVA-XJE1E2 based on sindbis virus vector could package HCV-like particles in eukaryotic cell, which provides a foundation for further study of its in vivo animal immune response.

[FMRI study of linguistic cortex in healthy Chinese individuals].

OBJECTIVE: To study the linguistic-functional cortex and identify the effect of age and sex on normal language processing by ER-fMRI and to observe whether a left or right predominance for linguistic-functional cortex exits or not. METHODS: A total of 50 healthy Chinese volunteers with right-hand dominance were divided into 4 groups according to gender and age: Group A, young male (< or =50 yr); Group B, young female ( < OR =50 yr); Group C, old male ( >50 yr); Group D, old female ( >50 yr). Each group finished 2 tasks of reading Chinese words loudly and silently. RESULTS: There were no statistical differences of activated voxel and intensity changes in linguistically functional cortex between healthy male and female individuals of different decades. The activated areas include bilateral frontal lobe, temporal lobe, parietal lobe, occipital lobe and bilateral cerebellar hemisphere. And there were no statistical difference of activated voxel and intensity changes in bilateral activated areas. Although the activated areas were not quite the same between two tasks and more activation elicited by overt-reading, but there was no statistical difference of activated voxel and intensity changes in the same activated areas. CONCLUSION: There is no age and gender difference in linguistic-function regions of healthy individual whose native language is Chinese. It is bilateral-equilibrium and no linguistic hemisphere's predominance exits. This characteristic is different from the left-hemisphere dominance of western languages. Although there is no statistical difference of activated voxel and intensity change between overt-reading and covert-reading, the activated areas of covert-reading are so unreliable that the way of covert-reading to study the linguistic-function regions of human brain is improper to some extent.

Metabolic changes of anterior cingulate cortex in patients with hepatic cirrhosis: A magnetic resonance spectroscopy study.

AIM: The anterior cingulate cortex (ACC) plays an important role in cognitive functions. The purpose of this study is to compare metabolite concentrations in the ACC of cirrhotic patients with normal controls, and to correlate metabolite changes with Child-Pugh class and with severity of hepatic encephalopathy (HE). METHODS: Fifty-two cirrhotic patients and 30 healthy volunteers were included in this study. All subjects performed the number connection test type A (NCT-A) and digital symbol test (DST) before multiple resonance (MR) examinations. Single-voxel proton MR spectroscopy (MRS) data in the ACC were acquired on a 1.5-T scanner. The ratios of all metabolites to creatine and phosphocreatine (Cr) were obtained. Statistical analysis was performed to evaluate the difference between control and cirrhotic patients, with respect to metabolite ratios. The correlation between metabolite ratios and Child-Pugh scale, severity of HE, venous ammonia and neuropsychiatric test results was analyzed. RESULTS: The ratios of choline (Cho)/Cr and myo-inositol (mIns)/Cr were significantly lower, and the ratio of glutamine- glutamate (Glx)/Cr was significantly higher in cirrhotic patients than those in controls (P < 0.001). mIns/Cr correlated negatively with Child-Pugh scale (r = -0.496, P < 0.001) and HE degree (r = -0.313, P < 0.05). Venous ammonia had a significant correlation with Cho/Cr (r = -0.329, P < 0.05) and mIns/Cr (r = -0.347, P < 0.05). No statistical correlation between metabolite ratios and neuropsychological tests was found for cirrhotic patients, but mIns/Cr did have a statistical correlation with NCT-A (r = -0.270, P < 0.05) and DST (r = 0.463, P < 0.001) when all subjects were included in the analysis. CONCLUSION: Significant metabolite changes were seen in the ACC in cirrhotic patients. Of the metabolites examined, the mIns/Cr level in the ACC was most closely associated with the severity of HE and hepatic functional reserve reflected by Child-Pugh scale.