Study of Gas Permeability and Separation Behaviour for Removal of High Content C02 from CH4 by Using Membrane Modelling

The removal of C02 from natural gas down to the pipeline quality is an important step before the natural gas can be sold to the end users. Typical natural gas treatment's specification requires that the composition of C02 in the treated gas cannot be more than 2 mole%. Currently, amine scrubbing units like Benfield process is extensively used to treat low content of C02 in the natural gas. For high concentration of C02 in the natural gas stream, the use of amine unit is economically restricted, as the recirculation rate needs to be increased to cater the need. The use of membrane separator to treat high content C02 natural gas has matured over the years and is said to work best at high C02 inlet partial pressure, as this results in increased permeation of the acid gas across the membrane. However, in the meantime to achieve low sale gas specification, the natural gas recovery in a membrane separator remains a question that needs to be explored. This modelling work comprises the study of gas permeability of pure C02 and CI-4 and the separation behaviour of C02 I CI-4 mixture under different process influences. The purpose is to predict the capability of membrane separator in separating high content C02 in the natural gas by using mathematical modelling. Data for y -alumina and acetate cellulose membranes, as cited from various references were used in this modelling work. The accuracy of the models developed, which incorporates the main transport mechanisms due to viscous, Knudsen and surface diffusion, was tested using experimental data cited. Simulation results show that the permeability of C02 and CH4 depend strongly on the pore size of the membrane, temperature and feed composition of the mixture. The effect of pressure on gas permeability is only apparent at small pore size. It was found that surface diffusion predominates the other transport mechanisms at small pores, and it poses the most selective transport mechanism to separate the C~ from CH4. However, when the pore size increases, surface diffusion starts to lose its effect as the gas molecules continue to diffuse via Knudsen diffusion mechanism. The results showed that Knudsen diffusion eventually increases the permeability of the gas molecules, but sacrifice in term of separation selectivity was observed at higher pore size. The contribution of viscous diffusion is not apparent as overall. The permeability of pure gas is inversely proportional to the system temperature, and directly proportional to the operating pressure at small pores only. The variation of surface diffusion due to the effects of both pressure and temperature is profound at small pore regions. The permeability of C02 and C~ in C02 I C~ mixture will approach the pure gas permeability as their feed composition increases. The investigation of separation behaviour of this binary system revealed that the performance of the single - stage alumina membrane separator is constant over a range of possible operating pressures. However, the separation factor decreases when the temperature increases. It showed that the separation factor of this binary system can be enhanced to be maximum at temperature near 80°C for separation that takes place in small pore region of the r -alumina membrane used. The separation factor is also a strong function of both the feed composition of C02 and the separation stage cut. Membrane separator becomes more efficient in term of selectivity and removal efficiency at high feed composition of C02 and higher stage cut. The high stage cut used to obtain sharp separation, however decreases the attractiveness of this binary separation due to increased loss of natural gas to the impurities stream

Study of Gas Permeability and Separation Behaviour for Removal of High Content C02 from CH4 by Using Membrane Modelling

The removal of C02 from natural gas down to the pipeline quality is an important step before the natural gas can be sold to the end users. Typical natural gas treatment's specification requires that the composition of C02 in the treated gas cannot be more than 2 mole%. Currently, amine scrubbing units like Benfield process is extensively used to treat low content of C02 in the natural gas. For high concentration of C02 in the natural gas stream, the use of amine unit is economically restricted, as the recirculation rate needs to be increased to cater the need. The use of membrane separator to treat high content C02 natural gas has matured over the years and is said to work best at high C02 inlet partial pressure, as this results in increased permeation of the acid gas across the membrane. However, in the meantime to achieve low sale gas specification, the natural gas recovery in a membrane separator remains a question that needs to be explored. This modelling work comprises the study of gas permeability of pure C02 and CI-4 and the separation behaviour of C02 I CI-4 mixture under different process influences. The purpose is to predict the capability of membrane separator in separating high content C02 in the natural gas by using mathematical modelling. Data for y -alumina and acetate cellulose membranes, as cited from various references were used in this modelling work. The accuracy of the models developed, which incorporates the main transport mechanisms due to viscous, Knudsen and surface diffusion, was tested using experimental data cited. Simulation results show that the permeability of C02 and CH4 depend strongly on the pore size of the membrane, temperature and feed composition of the mixture. The effect of pressure on gas permeability is only apparent at small pore size. It was found that surface diffusion predominates the other transport mechanisms at small pores, and it poses the most selective transport mechanism to separate the C~ from CH4. However, when the pore size increases, surface diffusion starts to lose its effect as the gas molecules continue to diffuse via Knudsen diffusion mechanism. The results showed that Knudsen diffusion eventually increases the permeability of the gas molecules, but sacrifice in term of separation selectivity was observed at higher pore size. The contribution of viscous diffusion is not apparent as overall. The permeability of pure gas is inversely proportional to the system temperature, and directly proportional to the operating pressure at small pores only. The variation of surface diffusion due to the effects of both pressure and temperature is profound at small pore regions. The permeability of C02 and C~ in C02 I C~ mixture will approach the pure gas permeability as their feed composition increases. The investigation of separation behaviour of this binary system revealed that the performance of the single - stage alumina membrane separator is constant over a range of possible operating pressures. However, the separation factor decreases when the temperature increases. It showed that the separation factor of this binary system can be enhanced to be maximum at temperature near 80°C for separation that takes place in small pore region of the r -alumina membrane used. The separation factor is also a strong function of both the feed composition of C02 and the separation stage cut. Membrane separator becomes more efficient in term of selectivity and removal efficiency at high feed composition of C02 and higher stage cut. The high stage cut used to obtain sharp separation, however decreases the attractiveness of this binary separation due to increased loss of natural gas to the impurities stream

Aural myiasis in a neonate in peninsular Malaysia

Myiasis is a pathological condition in humans and animals caused by various species of dipterous larvae. Myiasis which occurs in a newborn baby is referred as neonatal myiasis. It is a rare condition and there are only a few reports to date. A case of neonatal aural myiasis in a two day old infant is reported in this paper

The ‘Singapore Fever’ in China: policy mobility and mutation

The ‘Singapore Model’ has constituted the only second explicit attempt by the Communist Party of China (CPC) to learn from a foreign country following Mao Zedong’s pledge to contour ‘China’s tomorrow’ on the Soviet Union experience during the early 1950s. This paper critically evaluates policy transfers from Singapore to China in the post-Mao era. It re-examines how this Sino-Singaporean regulatory engagement came about historically following Deng Xiaoping’s visit to Singapore in 1978, and offers a careful re-reading of the degree to which actual policy borrowing by China could transcend different state ideologies, abstract ideas and subjective attitudes. Particular focus is placed on the effects of CPC cadre training in Singapore universities and policy mutation within two government-to-government projects, namely the Suzhou Industrial Park and the Tianjin Eco-City. The paper concludes that the ‘Singapore Model’, as applied in post-Mao China, casts institutional reforms as an open-ended process of policy experimentation and adaptation that is fraught with tension and resistance

Clinical Validation of an Ultra High-Throughput Spiral Microfluidics for the Detection and Enrichment of Viable Circulating Tumor Cells

Background: Circulating tumor cells (CTCs) are cancer cells that can be isolated via liquid biopsy from blood and can be phenotypically and genetically characterized to provide critical information for guiding cancer treatment. Current analysis of CTCs is hindered by the throughput, selectivity and specificity of devices or assays used in CTC detection and isolation. Methodology/Principal Findings: Here, we enriched and characterized putative CTCs from blood samples of patients with both advanced stage metastatic breast and lung cancers using a novel multiplexed spiral microfluidic chip. This system detected putative CTCs under high sensitivity (100%, n = 56) (Breast cancer samples: 12–1275 CTCs/ml; Lung cancer samples: 10–1535 CTCs/ml) rapidly from clinically relevant blood volumes (7.5 ml under 5 min). Blood samples were completely separated into plasma, CTCs and PBMCs components and each fraction were characterized with immunophenotyping (Pan-cytokeratin/CD45, CD44/CD24, EpCAM), fluorescence in-situ hybridization (FISH) (EML4-ALK) or targeted somatic mutation analysis. We used an ultra-sensitive mass spectrometry based system to highlight the presence of an EGFR-activating mutation in both isolated CTCs and plasma cell-free DNA (cf-DNA), and demonstrate concordance with the original tumor-biopsy samples. Conclusions/Significance: We have clinically validated our multiplexed microfluidic chip for the ultra high-throughput, low-cost and label-free enrichment of CTCs. Retrieved cells were unlabeled and viable, enabling potential propagation and real-time downstream analysis using next generation sequencing (NGS) or proteomic analysis.Singapore-MIT Alliance for Research and Technolog

The perspectives of health professionals and patients on racism in healthcare: A qualitative systematic review

Objective: To understand racial bias in clinical settings from the perspectives of minority patients and healthcare providers to inspire changes in the way healthcare providers interact with their patients. Methods: Articles on racial bias were searched on Medline, CINAHL, PsycINFO, Web of Science. Full text review and quality appraisal was conducted, before data was synthesized and analytically themed using the Thomas and Harden methodology. Results: 23 articles were included, involving 1,006 participants. From minority patients’ perspectives, two themes were generated: 1) alienation of minorities due to racial supremacism and lack of empathy, resulting in inadequate medical treatment; 2) labelling of minority patients who were stereotyped as belonging to a lower socio-economic class and having negative behaviors. From providers’ perspectives, one theme recurred: the perpetuation of racial fault lines by providers. However, some patients and providers denied racism in the healthcare setting. Conclusion: Implicit racial bias is pervasive and manifests in patient-provider interactions, exacerbating health disparities in minorities. Beyond targeted anti-racism measures in healthcare settings, wider national measures to reduce housing, education and income inequality may mitigate racism in healthcare and improve minority patient care

Perspectives on decision making amongst older people with end‐stage renal disease and caregivers in Singapore: a qualitative study

Background End‐stage renal disease (ESRD) is increasing both globally and in Asia. Singapore has the fifth highest incidence of ESRD worldwide, a trend that is predicted to rise. Older patients with ESRD are faced with a choice of haemodialysis, peritoneal dialysis or conservative management, all of which have their risks and benefits. Objective This study seeks to explore perspectives on decision making amongst older (≥70) Singaporean ESRD patients and their caregivers to undergo (or not to undergo) dialysis. Design Qualitative study design using semi‐structured interviews. Setting and participants Twenty‐three participants were recruited from the largest tertiary hospital in Singapore: seven peritoneal dialysis patients, five haemodialysis patients, four patients on conservative management and seven caregivers. Results While some patients believed that they had made an independent treatment decision, others reported feeling like they had no choice in the matter or that they were strongly persuaded by their doctors and/or family members to undergo dialysis. Patients reported decision‐making factors including loss of autonomy in daily life, financial burden (on themselves or on their families), caregiving burden, alternative medicine, symptoms and disease progression. Caregivers also reported concerns about financial and caregiving burden. Discussion and conclusion This study has identified several factors that should be considered in the design and implementation of decision aids to help older ESRD patients in Singapore make informed treatment decisions, including patients' and caregivers' decision‐making factors as well as the relational dynamics between patients, caregivers and doctors.This research was supported by the National Medical Research Council of Singapore (Grant Number: NMRC/HSRG/0080/2017), the Lien Centre for Palliative Care at Duke NUS Medical School and the National University Health System (NUHS) Singapore Population Health Improvement Centre (SPHERiC)(Grant Number: NMRC/CG/C026/2017_NUHS)

Structural, magnetic and electrical properties of PrMnO3/Pr0.67Ba0.33MnO3 single and bi-layer thin films

The single and bi-layer manganite thin film of PrMnO3 (PMO) and Pr0.67Ba0.33MnO3 (PBMO) were fabricated on single crystal MgO oriented (100) substrate via pulsed laser deposition technique. In this work, the importance of stacking sequence in bi-layer manganite films of PMO and PBMO was reported. The unit cell of PMO experienced negative misfit when growth on PBMO layer and positive misfit for the unit cell of PBMO growth on PMO. Modification of magnetic interaction was observed from the deduction of arrangement in magnetic spins ordering altered by deformation of crystal structure as well as the magnetic pinning effect among PMO and PBMO. The conducting route of PMO/PBMO or PBMO/PMO was follow PBMO layer which is lower in resistance. The highest %MR obtained from bi-layer films are lower compared to single layer PBMO (-50.0 % at 80Kin 10kG magnetic field). The stacking sequence of PMO/PBMO promises higher %MR than PBMO/PMO

Lattice strain effect in structural, magnetoresistance and electrical properties of La0.67Sr0.33MnO3 bulk and thin film system

Polycrystalline La0.67Sr0.33MnO3 (LSMO) powder prepared via conventional solid state reaction was pressed into pellet form. The pellets became target to growth thin films on corning glass (LSMO-C), fused silica (LSMO-FS) and MgO (100) (LSMO-M) substrate via pulsed laser deposition (PLD) method. XRD results showed that all samples were hexagonal structure with R-3C space group. Thin films showed relatively smaller crystallite size compared to bulk samples. From Rietveld Refinement analysis, all thin films experienced lattice strain when deposited on different substrate. LSMO compound deposited in different substrate induced structure distortion and lattice strain. Compression along c-axis occurred when the lattice strain increased thus shifted the metal-insulator transition temperature to lower temperature and increased its resistivity

A review of clinical and surgical outcomes of endoscopic endonasal skull base surgery in a Tertiary Center in Sarawak

Background: Endoscopic endonasal approach (EEA) for skull base tumor has been extensively developed in recent years. Objectives: To review the demographic data, indications, clinical presentations and surgical outcomes of endoscopic endonasal skull base surgeries performed. Methods: A retrospective analysis on all patients who had undergone endoscopic endonasal skull base surgery at the Skull Base Unit (ENT & Neurosurgery) from December 2013 to December 2015. Results: A total 34 cases were operated on during the study period. Female patients account for 44% of patients while 56% were male patients, with ages ranging from 8 to 77 years, with the mean age of 51.88 years. Majority of the cases were pituitary tumors (41%), followed by sinonasal tumors (15%), meningioma (12%), clival tumor (8%), cerebrospinal fluid (CSF) leak repair (8%) and frontal mucocoele (6%). Transsellar approach was the commonest approach (41%) followed by the transclival, transplanum, transfrontal approaches. In about 80% of cases, CSF leak was encountered intraoperatively and was successfully repaired endoscopically with the Hadad-Bassagasteguy flap and with the insertion of a lumbar drain. Only one case (3%) of CSF leak was noted postoperatively which was then successful repaired endoscopically with a nasoseptal flap. Systemic complications and intracranial infections were seen in 3 cases (8%) and were managed accordingly. No cases of epitaxis requiring surgical intervention were noted post operatively