Synthesis and characterization of novel cardo-containing copolyimide membranes for gas separation and effect of bulky site in the polymer backbone

A significant issue in environmental science is the climate change caused by global warming. The increase in the global temperature could lead to a range of negative effects that include rising sea levels, changes in ecosystems, loss of biodiversity, and reduction in crop yields. Currently, it is generally accepted that greenhouse gases such as carbon dioxide, methane, nitrous oxide, and fluorinated gases from fossil fuels and industrial wastes are primarily responsible for global warming. One method of slowing the rate of global warming is to reduce carbon dioxide emission into the air and to substitute fossil fuel for alternative energy sources. There are many methods of reducing greenhouse gas emissions, including improvements of energy efficiency, use of non-fossil fuel power sources, improved soil management, and the geological sequestration of carbon dioxide from significant greenhouse gas producing point sources. However, the most feasible and practical method at this moment is to capture the greenhouse gases from the fossil fuel combustion using amine absorption, physical adsorption, and membranes, etc. Membrane technology has been used for more than 50 years, and gas separation using membranes is used in several industrial processes such as the production of nitrogen from air, the separation of CO2 and H2O from natural gas, the purification of H2, and the recovery of vapors from vent gases, because it has various advantages such as low capital investment, ease of operation, and low energy consumption. To overcome the disadvantage of polyimide based materials in manufacturing and processing, researchers have developed various methods such as the introduction of flexible monomers, or chemical and thermal post-modification. One method to improve the properties of the membrane is the post-fabrication and thermal process, i.e. the thermally rearranged (TR) PBO membranes that exhibit excellent separation properties and superior thermal and chemical properties compared with commercialized engineering plastics. TR polymer membranes can be obtained from soluble polyimide containing functional groups such as –OH and –SH. The microcavity structure and distribution of soluble polyimide membranes are evolved during thermal treatment. In this study, we focus on the polyimide syntheses using both strategies of the introduction of bulky monomers and post-thermal treatments, yielding . synthesized 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA)-based copolyimide and hydroxyl monomer via polycondensation. In order to improve the gas separation properties and processability, we used highly CO2 permeable and selective monomers in the synthesis, and then evaluated the effect of the mole ratio monomers of the polymer on the gas separation performance. Finally, the copolyimide membrane was converted to a PBO structure via a thermal treatment in order to increase the rigidity and free volume of the polymer backbone. The degree of thermal conversion was controlled through varying the composition of the copolyimide. Then, the performances of the TR membranes were evaluated regarding their change in chemical structure, mechanical and thermal stability, and gas separation properties

Design and Implementation of Security OS: A Case Study

The importance of a security operating system (OS) with security-enhancing mechanisms at the kernel level, such as a reference monitor and a cryptographic file system, has been increasingly emphasized as the weaknesses and limitation of mechanisms at the user level have been revealed. However, when a system has only a reference monitor, the system is vulnerable to a low-level detour or a physical attack. In addition, when a system has only a cryptographic file system, the file system has a difficulty in protecting itself. To address these problems, we designed and developed a security OS with a reference monitor, a cryptographic file system, authentication limitation, and session limitation. Here we describe the model, its implementation, and its overheads

Key-hole Laminotomy (Translaminar Microsurgical Approach) for Upper Lumbar Herniated Disc

Objective The conventional microsurgical interlaminar approach for upper lumbar disc herniation (LDH) can increase the risk of postoperative spinal instability due to excessive laminectomy and/or facetectomy. The authors present a key-hole laminotomy (microsurgical translaminar approach) for upper LDH, which allows less destructive laminotomy, and review the results of this surgical technique. Methods Between 2007 and 2014, 20 patients underwent single level discectomy in the upper lumbar spine (L1-2 or L2-3) using a microsurgical translaminar approach. Mean patient age was 58.0±12.0 years and minimum follow-up was 1.0 years. A retrospective review of clinical and radiological data was conducted. Results Back pain and leg pain were improved from an average of 4.9±1.1 and 8.3±0.9 to 0.9±0.7 and 0.9±1.6 at 1-year postoperatively (p<0.001). According to Odom’s criteria, symptom improvement was significant at 1-year follow-up visits. Disc height at the operated level was decreased from 8.9±1.9 to 8.2±2.3 mm (p=0.043), and, total lumbar lordotic angle was increased from 26.8±10.8 to 36.6±10.6° (p=0.021). Excepting two case of post-operative additional nerve root block for remnant leg pain and recurrence there were no surgical complications. Conclusion The key-hole laminotomy for upper LDH achieved favorable clinical outcomes without iatrogenic instability. The described key-hole laminotomy provides a safe, effective alternative to the conventional interlaminar approach for upper LDH

EFFECTS OF LIQUID SWIRLING ON GAS-TO-LIQUID MASS TRANSFER IN THREE-PHASE FLUIDIZED BEDS

The swirling flow mode of liquid phase was adopted to promote the gas-to-liquid mass transfer in three-phase(gas-liquid-solid) fluidized beds. Effects of gas(0.01-0.09m/s) and liquid(0.035-0.172m/s) velocities, particle size(1.7-6.0mm) and swirling ratio of liquid phase(0-0.5) on the volumetric gas-to-liquid mass transfer coefficient in the bed were examined. The mass transfer coefficient increased up to 70% by adjusting the swirling flow of liquid phase, especially when the gas velocity is relatively low range. The value of gas-to-liquid mass transfer coefficient was well correlated in terms of dimensionless groups which were derived from the dimensional analysis on the mass transfer system

Inflammatory Polyarthritis in a Patient with Psoriasis: Is It Psoriatic Arthritis or Rheumatoid Arthrirtis?

Psoriatic arthritis (PsA) is an inflammatory arthritis associated with psoriasis. There are no generally accepted diagnostic criteria for PsA. Indeed, the diagnosis of this inflammatory arthritis is made by exclusion of other possible diseases and based upon immunologic, radiologic, and clinical features which are consistent with the diagnosis. Inflammatory arthritis in a patient with psoriasis can be an important clue for the diagnosis of PsA, but the possibility for diagnosis of other inflammatory arthritides ever remains. Herein we report a case of a female patient who was not diagnosed with PsA, but with rheumatoid arthritis, even though she had psoriasis

Multilevel Percutaneous Fenestrated Screw Fixation with Bone Cement Augmentation in Adult Lumbar Spinal Deformity

Objective Fenestrated screw fixation with bone cement augmentation has been demonstrated to increase the pullout strength. Bone cement augmentation is performed to prevent screw failure. The study aimed to investigate the safety and efficacy of multilevel percutaneous fenestrated screw fixation with bone cement augmentation in the adult lumbar spinal deformity. Methods We performed a retrospective study of 15 patients who underwent multilevel percutaneous fenestrated screw fixation (PFSF) with bone cement augmentation between January 2018 and December 2020. Visual analogue scale (VAS) score, Oswestry disability index (ODI), sagittal vertical axis (SVA), and lumbar lordosis (LL) were investigated in the patients. Results Mean BMD was -2.0. The mean percutaneous fenestrated screw fixation level was 6. The mean VAS score changed from 7.14 preoperatively to 4.57 postoperatively, to 3.71 at the last follow-up. The mean ODI changed from 45.21 preoperatively to 32.5 postoperatively, to 27.0 at the last follow-up. The mean LL changed from 23.6 preoperatively to 32.96 postoperatively, to 31.67 at the last follow-up. The mean SVA changed from 76.65 preoperatively to 46.15 postoperatively, to 48.46 at the last follow-up. The bony fusion rate was 73.3%. There were screw loosening in 4 patients and screw fracture in 3 patients. Cement leakage occurred towards the anterior body of the vertebrae in 2 patients but no symptoms were observed. Conclusion Our study results demonstrate that multilevel PFSF with bone cement augmentation can result in good clinical and radiological outcomes for lumbar spinal deformity. However, larger size screws or smaller through-hole screws are required to prevent screw fracture

Rocuronium bromide induced anaphylaxis in a child -A case report-

Anaphylaxis or anaphylactoid reaction in pediatric patient during anesthesia is rare. We report a rocuronium induced anaphylactic reaction in a 33-month-old female. The patient was scheduled to undergo escharectomy due to injuries suffered from a major burn. Shortly after administration of rocuronium, the patient developed severe hypotension, tachycardia, and hypoxia. A similar reaction occurred after administration of rocuronium on subsequent anesthesia. She underwent uneventful anesthesia with volatile induction and maintenance of anesthesia with sevoflurane on her next 7 operations without using of muscle relaxant

Partial Trisomy 1q41 Syndrome Delineated by Whole Genomic Array Comparative Genome Hybridization

Partial trisomy 1q syndrome is a rare chromosomal abnormality. We report on a male infant with 46,XY,der(11)t(1;11)(q41;p15.5) due to unbalanced segregation of the maternal reciprocal balanced translocation 46,XX,t(1;11)(q41;p15.5). The baby presented with a mild phenotype, characterized by a triangular face, almond-shaped eyes, low ears, short stature with relatively long legs, and mild psychomotor retardation. We utilized whole genomic array comparative genome hybridization (CGH) with 4,000 selected bacterial artificial chromosomes (BACs) to define the chromosomal breakpoints and to delineate the extent of the partial trisomy in more detail. To our knowledge, this is the first case of nearly pure "partial trisomy 1q41" defined by whole genomic array CGH