Surface Passivation of Layered MoSe2 via van der Waals Stacking of Amorphous Hydrocarbon.

Development of efficient surface passivation methods for semiconductor devices is crucial to counter the degradation in their electrical performance owing to scattering or trapping of carriers in the channels induced by molecular adsorption from the ambient environment. However, conventional dielectric deposition involves the formation of additional interfacial defects associated with broken covalent bonds, resulting in accidental electrostatic doping or enhanced hysteretic behavior. In this study, centimeter-scaled van der Waals passivation of transition metal dichalcogenides (TMDCs) is demonstrated by stacking hydrocarbon (HC) dielectrics onto MoSe2 field-effect transistors (FETs), thereby enhancing the electric performance and stability of the device, accompanied with the suppression of chemical disorder at the HC/TMDCs interface. The stacking of HC onto MoSe2 FETs enhances the carrier mobility of MoSe2 FET by over 50% at the n-branch, and a significant decrease in hysteresis, owing to the screening of molecular adsorption. The electron mobility and hysteresis of the HC/MoSe2 FETs are verified to be nearly intact compared to those of the fabricated HC/MoSe2 FETs after exposure to ambient environment for 3 months. Consequently, the proposed design can act as a model for developing advanced nanoelectronics applications based on layered materials for mass production.

Quantitation of propionic acid in emmental cheese products by direct solvent extraction.

Propionic acid (PA) is commonly present in Emmental cheese (EM) with relatively high concentration. Even though PA is allowed as GRAS in the USA, it may cause neurological disorders if it is consumed excessively. The maximum level of the preservative PA in cheese is set at 3.0 g/kg by the Korean Food Code. Also, the minimum level of PA in EM (150 mg / 100 g) was set by Codex in 1967. Therefore, PA monitoring in EM, with relatively high level of intrinsic PA, is necessary to recommend the sound use of the PA in the EM ripened. The current official PA analysis method consisting of steam distillation and solvent extraction / evaporation, is too cumbersome to be handled in sample preparation process. In this study, acidic acetone-based direct extraction method was successfully applied to 12 EM samples for the determination of PA level.

Serum Lactate Could Predict Mortality in Patients With Spontaneous Subarachnoid Hemorrhage in the Emergency Department.

Background: Serum lactate is a useful biomarker for prediction of mortality in critically ill patients. The purpose of this study was to identify if serum lactate could be used as a biomarker for predicting mortality in patients with subarachnoid hemorrhage (SAH) in the emergency department. Methods: This retrospective study enrolled 189 patients. Baseline demographic data and clinical characteristics of patients were obtained from medical record review. Multiple logistic regression analysis was performed to determine predictor variables significantly associated with mortality. Receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of variables for mortality prediction in SAH. Results: Using multivariate logistic regression analysis, age [OR 1.05; 95% confidence interval (CI) 1.00-1.10; p = 0.037], Hunt and Hess scale score (OR 3.29; 95% CI 1.62-6.70; p = 0.001), serum lactate level (OR 1.33; 95% CI 1.03-1.74; p = 0.032), and serum glucose level (OR 1.01; 95% CI 1.00-1.02; p = 0.049) predicted overall mortality in SAH. The area under the ROC curve (AUC) value for the use of serum lactate level to predict mortality in SAH was 0.815 (95% CI 0.753-0.868) (p < 0.001). Conclusion: Serum lactate may be a useful biomarker for the early prediction of mortality in SAH patients in the emergency department.

Production of a fermented organic rice syrup with higher isomalto-oligosaccharide using Lactobacillus plantarum.

Isomalto-oligosaccharide (IMO) syrup was prepared from organic rice, in which Lactobacillus plantarum as a starter was inoculated to raise its purity and also produce a fermented rice beverage. Of the five strains of lactic acid bacteria tested, L. plantarum was preferentially selected in terms of a viable cells (7.3 × 108 colony forming unit (CFU/mL) and higher dry cell weight (13 mg/mL). The fermented syrup-based medium did not affect the growth of L. plantarum. As expected, the residual sugar content gradually decreased by 1.34% compared with the initial concentration. It was apparent that the residual sugars but not oligosaccharides were removed during the L. plantarum fermentation period. The production of lactic acid was the highest (8125.78 mg/kg) among the organic acids produced in the fermented IMO syrup.

Galactooligosaccharide and Sialyllactose Content in Commercial Lactose Powders from Goat and Cow Milk.

The most commonly used infant formulas contain lactose originating from cow milk. Goat milk has recently been claimed to be nutritionally more effective for infants than other milks. In baby foods, much emphasis is placed on the concentrations of intestinal microflora-promoting oligosaccharides, which are generally transferred into lactose from milk during crystallization process. Here we show that higher level of free sialic acid is present in goat lactose powder compared to cow lactose powder. Without proteinase K treatment, the amount of 3-sialyllactose and 6-sialyllactose were similar in goat and cow lactose powders. However, after proteolysis, 6-sialyllactose was present at higher levels in goat than in cow lactose powder. Galactooligosaccharides, a group of prebiotics, are present in milk in the form of glycoproteins. Galactooligosaccharide content was also higher in goat lactose powder than in cow lactose powder.

2nd dimensional GC-MS analysis of sweat volatile organic compounds prepared by solid phase micro-extraction.

The characteristics of an individual's odor from sweat, breath and skin provide important information for criminal tracking in field of forensic science. Solid phase micro-extraction gas chromatography/mass spectrometry (SPME-GC/MS) was used to determine human sweat volatile organic compounds (VOCs) profiles. The mass spectrometric analysis (with electron impact mode) followed by 2nd dimensional separation with two different GC columns (one polar and one relatively nonpolar) connected in parallel were used to identify the 574 compounds from sweat samples. The components included alcohols, aldehydes, aliphatics/aromatics, carboxylic acids, esters, ketones, and other organic compounds (amides/amines, thio/thioesters, oxide, sulfides, nitro compounds). Of these compounds, 1-tridecanol, 1,3-bis(1,1-dimethyl ethyl)-benzene, 4,4'-(1-methylethylidene) bis-phenol and 7-acetyl-6-ethyl-1,1,4,4,-tetramethyl-tetraline were common components in all donor's sweat volatile samples. Age-related specific compounds were also detected. The results suggest that characteristic volatile profiles of human sweat emanations could provide the valuable information to forensic scientists.

Investigation of the cyanuric acid contamination caused by acetonitrile and alkali detergent for the LC-ESI MS/MS analysis.

During the replicate analysis of melamine and cyanuric acid by LC-ESI MS/MS for the method development, recurring cyanuric acid contamination was observed. The high concentration (6,950 mg/kg) of cyanuric acid was found in the strong alkali detergent used in a glassware washing machine. However, only small concentration of cyanuric acid (0.002-0.004 mg/kg) was detected in the glassware washed with the above alkali detergent. The major contamination source of cyanuric acid was some specific lot of acetonitrile (0.093 mg/kg) that increased the background level of the ion chromatogram.

Butyl and phenyl tin compounds in fish and shellfish on the Korean market.

The degree of organotin contamination was determined in samples of ten species of fish and shellfish that were representative of the Korean fish market. Shellfish and fish samples were collected in the fish markets of eight big cities in Korea (Gangneung, Ulsan, Pusan, Daegu, Guangju, Daejun, Incheon and Seoul). The edible portion of total 160 samples were analyzed for organotin compounds such as monobutltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPT), diphenyltin (DPT) and TPT (triphenyltin) by GC-MSD SIM mode after propylation and Florisil clean-up. Generally organotin levels of fish were higher than shellfish. The highest concentration of TBT was found in mackerel (average 67.02 ng/g-wet wt.) among fish and shellfish. TBT usually accounted higher percentage than that of MBT and DBT in most samples. However, the average concentration order of PTs in the tested samples was MPT > TPT > DPT except saury.

Monitoring of residual pesticides in herbal drug materials of Korea and China.

The information of the pesticide residues in herbal drug materials (HDMs) is not sufficient to support the scientific risk management so far. Therefore, 30 types of HDMs such as the herba of Artemisia montana were analyzed for 47 different pesticides. Among 292 samples, eight Chinese and one Korean HDMs were contaminated with five pesticides such as methoxychlor, DDT, gamma-BHC, endosulfan, and procymidone (0.044-0.501 mg/kg). The detection rate of pesticides in the tested HDMs was determined as 3.1%. On critical observation of the detected amount of procymidone (0.501 mg/kg) and methoxychlor (0.382 and 0.312 mg/kg), further intensive monitoring of the pesticides might be necessary for HDMs.

Multi residual pesticide monitoring in commercial herbal crude drug materials in South Korea.

In order to reduce health risks from residual pesticides in herbal drug products, the residue information of pesticides should be acquired. Therefore, 38 commodities (229 herbal crude drug materials) were analyzed for 44 different pesticides. Among the 229 samples (36 types of herbal crude drugs), seven imported and two domestic drug materials were contaminated with eight pesticides (0.034-0.579 mg/kg) such as BHC, procymidone, endosulfan, etc. Among the eight detected pesticides, four were fungicides, which were found in underground crude drug materials such as rhizoma or radix.