Attrition rate of iron ore in the gas-solid fluidized beds with the wide size distribution

The effects of superficial gas velocity (Ug = 1.25 – 3.00 m/s) and distributor hole size (8.0 – 12.4 mm) on the attrition rate of iron ore in a gas-solid fluidized bed with 0.076 m ID ´ 3.7 m height with or without circulation were investigated. The particle density and the Sauter mean diameter of fresh iron ore were 3,705 kg/m3 and 357 m, respectively. When the kinetic energy rate from the orifice was equal or greater than 180 J/s, the trend of attrition rate could be determined. The attrition rate was determined by measuring the fractional mass of fine particle formation (- 500 m fraction) during 30 min without circulation. In experiments with circulation, the attrition rate was determined by measuring a different threshold size, 63 m. The attrition rate increases with increasing kinetic energy rate from the orifice (J/s). The kinetic energy rate from the orifice was calculated using the mass flow rate and orifice nozzle velocity. The correlation of attrition rate with the kinetic energy rate from the orifice was. When the bed height rapidly decreased below the jet length under very severe conditions, the attrition rate did not follow the correlation

Effects of antidepressants on the conformation of phospholipid headgroups studied by solid-state NMR

The effect of tricyclic antidepressants (TCA) on phospholipid bilayer structure and dynamics was studied to provide insight into the mechanism of TCA-induced intracellular accumulation of lipids (known as lipidosis). Specifically we asked if the lipid–TCA interaction was TCA or lipid specific and if such physical interactions could contribute to lipidosis. These interactions were probed in multilamellar vesicles and mechanically oriented bilayers of mixed phosphatidylcholine–phosphatidylglycerol (PC–PG) phospholipids using 31 P and 14 N solid-state NMR techniques. Changes in bilayer architecture in the presence of TCAs were observed to be dependent on the TCA's effective charge and steric constraints. The results further show that desipramine and imipramine evoke distinguishable changes on the membrane surface, particularly on the headgroup order, conformation and dynamics of phospholipids. Desipramine increases the disorder of the choline site at the phosphatidylcholine headgroup while leaving the conformation and dynamics of the phosphate region largely unchanged. Incorporation of imipramine changes both lipid headgroup conformation and dynamics. Our results suggest that a correlation between TCA-induced changes in bilayer architecture and the ability of these compounds to induce lipidosis is, however, not straightforward as imipramine was shown to induce more dramatic changes in bilayer conformation and dynamics than desipramine. The use of 14 N as a probe was instrumental in arriving at the presented conclusions. Copyright © 2004 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34947/1/1327_ftp.pd

Determination of Α-helix and Β-sheet stability in the solid state: A solid-state NMR investigation of poly( L -alanine)

The relative stability of Α-helix and Β-sheet secondary structure in the solid state was investigated using poly( L -alanine) (PLA) as a model system. Protein folding and stability has been well studied in solution, but little is known about solid-state environments, such as the core of a folded protein, where peptide packing interactions are the dominant factor in determining structural stability. 13 C cross-polarization with magic angle spinning (CPMAS) NMR spectroscopy was used to determine the backbone conformation of solid powder samples of 15-kDa and 21.4-kDa PLA before and after various sample treatments. Reprecipitation from helix-inducing solvents traps the Α-helical conformation of PLA, although the method of reprecipitation also affects the conformational distribution. Grinding converts the secondary structure of PLA to a final steady-state mixture of 55% Β-sheet and 45% Α-helix at room temperature regardless of the initial secondary structure. Grinding PLA at liquid nitrogen temperatures leads to a similar steady-state mixture with 60% Β-sheet and 40% Α-helix, indicating that mechanical shear force is sufficient to induce secondary structure interconversion. Cooling the sample in liquid nitrogen or subjecting it to high pressure has no effect on secondary structure. Heating the sample without grinding results in equilibration of secondary structure to 50% Α-helix/50% Β-sheet at 100°C when starting from a mostly Α-helical state. No change was observed upon heating a Β-sheet sample, perhaps due to kinetic effects and the different heating rate used in the experiments. These results are consistent with Β-sheet approximately 260 J/mol more stable than Α-helix in solid-state PLA. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 246–254, 2002Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34326/1/10180_ftp.pd

Lack of prognostic significance for major adverse cardiac events of soluble suppression of tumorigenicity 2 levels in patients with ST-segment elevation myocardial infarction

Background: Elevation of soluble suppression of tumorigenicity 2 (sST2) is associated with cardiac fibrosis and hypertrophy. Under investigation herein, was whether sST2 level is associated with major adverse cardiac events (MACE) and left ventricular (LV) remodeling after primary percutaneous coronary intervention (PCI) in patients with acute ST-segment elevation myocardial infarction (STEMI). Methods: In total, this study included 184 patients who underwent successful primary PCI. A subsequent guideline-based medical follow-up was included (61.4 ± 11.8 years old, 85% male, 21% with Killip class ≥ I). sST2 concentration correlations with echocardiographic, angiographic, laboratory parameters, and clinical outcomes in STEMI patients were evaluated. Results: The median sST2 level was 60.3 ng/mL; 6 (3.2%) deaths occurred within 1 year. The sST2 level correlated with LV ejection fraction (LVEF) changes from baseline to 6 months (r= –0.273; p = 0.006) after adjustment for echocardiographic parameters including wall motions score index (WMSI). Recovery of LVEF at 6 months was highest in the tertile 1 group (Δ6 months – baseline LVEF; tertile 1, p = 0.001; tertile 2, p = 0.319; tertile 3, p = 0.205). The decrease in WMSI at 6 months was greater in the tertiles 1 and 2 groups than in the tertile 3 group (Δ6 months – baseline WMSI; tertile 1, p = 0.001; tertile 2, p = 0.013; tertile 3, p = 0.055). There was no association between sST2 levels and short-term (log rank p = 0.598) and long-term (p = 0.596) MACE. Conclusions: sST2 concentration have predictive value for LV remodeling on echocardiography in patients with STEMI who underwent primary PCI. However, sST2 concentration was not associated with short-term and long-term MACE

An Evaluation of the Weibull and the Logistic Models for Cox's Proportional Hazards Model

Cox's proportional hazards model has been widely used in medical researches to evaluate the relationship between prognostic factors of a disease and the occurrence of outcome event. On a theoretical basis, regression coefficient estimated from Cox's proportional hazards model could be approximated by using the Weibull and the logistic model. Breast cancer cases (n=86) diagnosed at the Seoul National University Hospital were selected to evaluate the possibility of some accelerated models as an approximate model to Cox's proportional hazards model. Age at operation, tumor size and lymph node metastasis were the variables concerned in this study. Parameter estimates of two variables from the Weibull model, which seemed not to violate the proportionality assumption of Cox's model, showed almost identical values to those from Cox's proportional hazards model. However, there was a substantial degree of discrepancy in the parameter estimate of another variable, which showed an apparent unproportionality. This study confirmed that both the Weibull and the logistic models could be used as approximate methods to the estimates from Cox's proportional hazards model. Particularly noteworthy was the fact that the PC-SAS system could be successfully applied to survival analysis when the parameters were going to be estimated using Cox's model

Assessment of the conventional radial artery with optical coherent tomography after the snuffbox approach

Background: This study aimed to evaluate acute injuries of the radial artery (RA) using optical coherence tomography (OCT) in patients who underwent coronary intervention via the snuffbox approach. Methods: Forty-six patients, who underwent coronary intervention and assessment of the conventional RA using OCT via the snuffbox approach, were enrolled from two university hospitals between August 2018 and August 2019. Results: The mean age of the patients was 65.1 years. In this study population, 6-French (Fr) sheaths were used. The mean diameter of the conventional RA was 2.89 ± 0.33 mm, and the mean lumen area of the conventional RA was 6.68 ± 1.56 mm2. Acute injuries of the conventional RA, after the snuffbox approach, were observed in 5 (10.9%) patients. Intimal tear was observed in the RA in 1 (2.2%) case. Intraluminal thrombi, without vessel injuries, were detected in the RA in 4 (8.7%) cases. However, medial dissection was not observed in the OCT analysis. Conclusions: This retrospective OCT-based study showed that the diameter of the conventional RA was 2.89 mm and acute vessel injury of the conventional RA was rare in patients who underwent coronary intervention via the snuffbox approach

Association between shift work and obesity among female nurses: Korean Nurses’ Survey

Background: Shift work has been hypothesized as a risk factor for obesity. In this study, we investigated the association between current shift work and body mass index (BMI) among female nurses in Korea. The relationship between duration of shift work and BMI of the participants was also evaluated. Methods: This cross-sectional survey evaluated participants in the Korean Nurses’ Survey, conducted from October to December 2011, using web-based self-administered questionnaires. A total of 9,989 nurses were included among 10,000 who registered on the survey web site (5,287 shift workers and 4,702 non-shift workers). Current shift workers were divided into tertiles of shift work duration (0.08–3.00 years, n = 1,732; 3.08–6.75 years, n = 1,731; and 6.83–38.00 years, n = 1,686). The BMI thresholds of overweight and obesity were ≥23 kg/m2 and ≥25 kg/m2, respectively. Data were analyzed using SPSS software. Results: Mean participant age was 33.2 ± 8.6 years and the mean BMI was 20.9 ± 2.5 kg/m2. There were statistically significant differences in current smoking status, regular drinking habit, dietary habits, regular exercise, sleep problems and self-perceived health status according to duration of shift work. The overall prevalence of overweight/obesity (18.6%) and obesity (7.4%) increased significantly as shift work duration increased from the lowest to highest tertile (P for trend <0.001). Multivariate logistic regression analysis revealed no association between current shift work and BMI. However, after adjusting for potential confounders, the participants with the longest duration of shift work were 1.63 (95% CI, 1.22–2.17) times more likely to be overweight or obese than those with the shortest duration. There was a significant positive association between obesity and shift work duration in the unadjusted analysis; however, it was attenuated and no longer significant in the multivariate model. Conclusions: The duration of shift work was positively associated with prevalence of overweight/obesity in nurses in Korea. Although these findings need to be confirmed in prospective studies, they suggest that special attention should be paid to female nurses with a long duration of shift work

Anesthetic management for emergent Cesarean section in a patient with toxic epidermal necrolysis -A case report-

Toxic epidermal necrolysis (TEN) is rare but serious cutaneous reaction with significant mortality and long-term morbidity. Various etiologies, particularly numerous medications and infectious agents have been implicated. It is characterized as inflammatory bullous lesions of the skin and mucous membrane and can develop serious complications such as pneumonia, pneumothorax, sepsis and renal failure. In general, patients with TEN are managed as severe second-degree burn patients with preventing excessive fluid deficit and infections. In this case, we aimed to present anesthetic management of a 26-year-old pregnant woman with TEN who received general anesthesia during emergent cesarean section

Synthesis and Solubility Study of the Polyamides Containing 4,4'-(9- fluorenylidene)dianiline in the Backbone as an Antireflecting Spin-on Hardmask Materials

Due to the continuous demand for smaller microelectronic devices, there exists a need to reduce the size of structural shapes in microelectronics and other related industries. Toward this end, effective lithographic techniques are essential to achieve a reduction in the size of microelectronic structures. Typical lithographic processes involve etch resistant photoresist underlying materials having antireflecting properties at a certain wavelength exposure. In this work, such materials were synthesized by the step-polymerization of diamines 2,2'-bis(3-amino- 4-hydroxyphenyl)hexafluoropropane (6FP) and 4,4'-(9-fluorenylidene)dianiline (BAFL) with a variety of diacid chlorides [terepthaloyl, isophthaloyl, glutaryl, and succinyl chlorides] and characterized by 1H NMR in tetrahydrofuran (THF-d8), and gel permeation chromatography (GPC) using polystyrene standards. The effect of the structure of the components on the copolymer solubility in mixture of propylene glycol monoethylether acetate (PGMEA) and cyclohexanone used in microelectronics processing was studied by UV-visible spectroscopy. The solubility of the copolymers was found to be in trade-off relationship with BAFL content needed for its antireflective properties and high plasma etch resistance. The polymers that were prepared by using the equimolar mixture of isophthaloyl dichloride and glutaryl dichloride equimolar mixture showed the best solubility, processability and functionality and are applicable as spin-on antireflecting hardmask materials for deep ultra violet (DUV) litfhography technology. They showed good coatability, chemical resistance, plasma etch resistance, and plasma etch selectivity