Alginate/PVA Polymer Electrolyte Membrane Modified by Hydrophilic Montmorillonite for Structure and Selectivity Enhancement for DMFC Application.

Nafion is a commercial membrane that is widely used in direct methanol fuel cells (DMFC) but has critical constraints such as being expensive and having high methanol crossover. Efforts to find alternative membranes are actively being carried out, including in this study, which looks at producing a Sodium Alginate/Poly (Vinyl Alcohol) (SA/PVA) blended membrane with modification by montmorillonite (MMT) as an inorganic filler. The content of MMT in SA/PVA-based membranes varied in the range of 2.0-20 wt% according to the solvent casting method implemented. The presence of MMT was seen to be most optimal at a content of 10 wt%, achieving the highest proton conductivity and the lowest methanol uptake of 9.38 mScm-1 and 89.28% at ambient temperature, respectively. The good thermal stability, optimum water absorption, and low methanol uptake of the SA/PVA-MMT membrane were achieved with the presence of MMT due to the strong electrostatic attraction between H+, H3O+, and -OH ions of the sodium alginate and PVA polymer matrices. The homogeneous dispersion of MMT at 10 wt% and the hydrophilic properties possessed by MMT contribute to an efficient proton transport channel in SA/PVA-MMT membranes. The increase in MMT content makes the membrane more hydrophilic. This shows that the loading of 10 wt% MMT is very helpful from the point of view of sufficient water intake to activate proton transfer. Thus, the membrane produced in this study has great potential as an alternative membrane with a much cheaper cost and competent future performance.

Body composition reference values in Singaporean adults using dual-energy X-ray absorptiometry-The Yishun study.

OBJECTIVES: This study establishes age- and sex-specific reference values for fat mass index (FMI), lean mass index (LMI), appendicular LMI (aLMI), and body fat distribution indices including Android/Gynoid % fat ratio and Trunk/Limb % fat ratio in multi-ethnic Singaporean adults. METHODS: A population-based cross-sectional study using dual-energy X-ray absorptiometry (Hologic Discovery Wi) was carried out to measure whole body and regional fat and lean mass in community-dwelling adults. A total of 537 adults (57.5% women), aged from 21 to 90 years, were recruited from the large north-eastern residential town of Yishun. Age- and sex-specific percentile reference values were generated for FMI, LMI, aLMI, Android/Gynoid % fat ratio and Trunk/Limb % fat ratio using the Lambda-Mu-Sigma method. The relationship between the parameters and age were assessed through the Pearson's correlation coefficient. RESULTS: All parameters demonstrated significant correlation with age (p < 0.05) for both men and women, except for LMI in women, with the strength of r ranging from 0.12 (weak correlation) to 0.54 (strong correlation). LMI (r = -0.45) and appendicular LMI (r = -0.54) were negatively associated with age in men while none (r = -0.06) to weak correlation (r = -0.14) were shown in women for the same parameters respectively. The Android/Gynoid % fat ratio and Trunk/Limb % fat ratio were positively related to age for both men (r = 0.37 & 0.43, p < 0.001) and women (r = 0.52 & 0.48, p < 0.001). CONCLUSION: We have established DXA-based body composition reference data for the Singapore adult population. These reference data will be particularly useful in geriatric, obesity and oncology clinics, enabling the prescription of appropriate therapy to individuals at risk of morbidity from unfavorable body composition phenotypes. It also adds on to the limited reference database on Southeast Asian body composition.

Proton Conductivity Enhancement at High Temperature on Polybenzimidazole Membrane Electrolyte with Acid-Functionalized Graphene Oxide Fillers.

Graphene oxide (GO) and its acid-functionalized form are known to be effective in enhancing the proton transport properties of phosphoric-acid doped polybenzimidazole (PA-doped PBI) membranes utilized in high-temperature proton exchange membrane fuel cells (HTPEMFC) owing to the presence of proton-conducting functional groups. This work aims to provide a comparison between the different effects of GO with the sulfonated GO (SGO) and phosphonated GO (PGO) on the properties of PA-doped PBI, with emphasis given on proton conductivity to understand which functional groups are suitable for proton transfer under high temperature and anhydrous conditions. Each filler was synthesized following existing methods and introduced into PBI at loadings of 0.25, 0.5, and 1 wt.%. Characterizations were carried out on the overall thermal stability, acid doping level (ADL), dimensional swelling, and proton conductivity. SGO and PGO-containing PBI exhibit better conductivity than those with GO at 180 °C under anhydrous conditions, despite a slight reduction in ADL. PBI with 0.5 wt.% SGO exhibits the highest conductivity at 23.8 mS/cm, followed by PBI with 0.5 wt.% PGO at 19.6 mS/cm. However, the membrane with PGO required a smaller activation energy for proton conduction, thus less energy was needed to initiate fast proton transfer. Additionally, the PGO-containing membrane also displayed an advantage in its thermal stability aspect. Therefore, considering these properties, it is shown that PGO is a potential filler for improving PBI properties for HTPEMFC applications.

Nata de Cassava Type of Bacterial Cellulose Doped with Phosphoric Acid as a Proton Exchange Membrane.

This work aims to encourage the use of natural materials for advanced energy applications, such as proton exchange membranes in fuel cells. Herein, a new conductive membrane produced from cassava liquid waste was used to overcome environmental pollution and the global crisis of energy. The membrane was phosphorylated through a microwave-assisted method with different phosphoric acid, (H3PO4) concentrations (10-60 mmol). Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), dynamic mechanical analysis (DMA), swelling behavior test, and contact angle measurement were carried out on the membrane doped with different H3PO4 levels. The phosphorylated NdC (nata de cassava) membrane doped with 20 mmol (NdC20) H3PO4 was successfully modified and significantly achieved proton conductivity (maximum conductivity up to 7.9 × 10-2 S cm-1 at 80 °C). In addition, the fabricated MEA was assembled using an NdC20 membrane with 60 wt% Pt/C loading of 0.5 mg cm-2 for the anode and cathode. Results revealed that a high power density of 25 mW cm-2 was obtained at 40 °C operating temperature for a single-cell performance test. Thus, this membrane has the potential to be used as a proton exchange membrane because it is environment-friendly and inexpensive for fuel cell applications.

Hybrid Composite Membrane of Phosphorylated Chitosan/Poly (Vinyl Alcohol)/Silica as a Proton Exchange Membrane.

Chitosan is one of the natural biopolymers that has been studied as an alternative material to replace Nafion membranes as proton change membranes. Nevertheless, unmodified chitosan membranes have limitations including low proton conductivity and mechanical stability. The aim of this work is to study the effect of modifying chitosan through polymer blending with different compositions and the addition of inorganic filler on the microstructure and physical properties of N-methylene phosphonic chitosan/poly (vinyl alcohol) (NMPC/PVA) composite membranes. In this work, the NMPC biopolymer and PVA polymer are used as host polymers to produce NMPC/PVA composite membranes with different compositions (30-70% NMPC content). Increasing NMPC content in the membranes increases their proton conductivity, and as NMPC/PVA-50 composite membrane demonstrates the highest conductivity (8.76 × 10-5 S cm-1 at room temperature), it is chosen to be the base membrane for modification by adding hygroscopic silicon dioxide (SiO2) filler into its membrane matrix. The loading of SiO2 filler is varied (0.5-10 wt.%) to study the influence of filler concentration on temperature-dependent proton conductivity of membranes. NMPC/PVA-SiO2 (4 wt.%) exhibits the highest proton conductivity of 5.08 × 10-4 S cm-1 at 100 °C. In conclusion, the study shows that chitosan can be modified to produce proton exchange membranes that demonstrate enhanced properties and performance with the addition of PVA and SiO2.

Radiation-Grafted Anion-Exchange Membrane for Fuel Cell and Electrolyzer Applications: A Mini Review.

This review discusses the roles of anion exchange membrane (AEM) as a solid-state electrolyte in fuel cell and electrolyzer applications. It highlights the advancement of existing fabrication methods and emphasizes the importance of radiation grafting methods in improving the properties of AEM. The development of AEM has been focused on the improvement of its physicochemical properties, including ionic conductivity, ion exchange capacity, water uptake, swelling ratio, etc., and its thermo-mechano-chemical stability in high-pH and high-temperature conditions. Generally, the AEM radiation grafting processes are considered green synthesis because they are usually performed at room temperature and practically eliminated the use of catalysts and toxic solvents, yet the final products are homogeneous and high quality. The radiation grafting technique is capable of modifying the hydrophilic and hydrophobic domains to control the ionic properties of membrane as well as its water uptake and swelling ratio without scarifying its mechanical properties. Researchers also showed that the chemical stability of AEMs can be improved by grafting spacers onto base polymers. The effects of irradiation dose and dose rate on the performance of AEM were discussed. The long-term stability of membrane in alkaline solutions remains the main challenge to commercial use.

Risk perception in paranoia and anxiety: Two investigations across clinical and non-clinical populations.

OBJECTIVES: It is common, among clinical and non-clinical populations alike, for paranoia and anxiety to co-occur. It has been suggested that anxiety and its related appraisal styles may contribute to development of paranoia. We aimed to evaluate different aspects of risk perception in relation to paranoia and anxiety and to identify specific aspects that may differentiate paranoia from anxiety. This paper consists of two inter-related studies. METHODS: Study 1 compared 30 patients with persecutory delusions, 21 patients with generalized anxiety disorder and 52 healthy controls. Study 2 compared 30 non-clinical individuals with high levels of paranoia and anxiety, 28 individuals with high anxiety only and 36 healthy controls. Within each study, the two symptomatic groups were matched on level of anxiety. Four dimensions of risk perception (i.e. likelihood, harm, controllability, and intentionality) were compared across groups, as measured by the locally validated Risk Perception Questionnaire. RESULTS: In both studies, the paranoia and the anxiety groups reported an elevated perceived likelihood of negative events than controls respectively. Only the paranoia groups reported an elevated perceived harm of neutral events than controls. In Study 2, the two at-risk groups attributed more harm and intentionality to negative events than controls. CONCLUSION: Although perception of negative events was characteristic in anxiety (with or without paranoia), a biased perception of neutral events as risky was unique to the addition of paranoia. Implications to the transdiagnostic and continual view of psychopathology, and mechanism-based interventions were discussed.

Facing a disruptive threat: how can a nuclear medicine service be prepared for the coronavirus outbreak 2020?

PURPOSE: The aim of this short communication is to outline our experience in policies and processes of a nuclear medicine service during the COVID-19 outbreak in Singapore. METHODS: We describe the key considerations of policies and processes that have been implemented in our nuclear medicine service since the first case of COVID-19 was confirmed in Singapore General Hospital on 23 January 2020, up to the present time. RESULTS: Infection control, screening of patients and visitors, segregation of risk groups, segregation of staff and service continuity plans, communication and staff welfare, using electronic platforms for multi-disciplinary meetings and tele-reporting are discussed. CONCLUSION: Since our hospital received the first patient with COVID-19 in Singapore, our centre has managed 16 COVID-19 cases to date. There has not been any healthcare worker in our institution who has contracted COVID-19 through patient contact. We have highlighted for discussion some of the policies and processes to prepare a nuclear medicine service for the COVID-19 threat.

Review of Chitosan-Based Polymers as Proton Exchange Membranes and Roles of Chitosan-Supported Ionic Liquids.

Perfluorosulphonic acid-based membranes such as Nafion are widely used in fuel cell applications. However, these membranes have several drawbacks, including high expense, non-eco-friendliness, and low proton conductivity under anhydrous conditions. Biopolymer-based membranes, such as chitosan (CS), cellulose, and carrageenan, are popular. They have been introduced and are being studied as alternative materials for enhancing fuel cell performance, because they are environmentally friendly and economical. Modifications that will enhance the proton conductivity of biopolymer-based membranes have been performed. Ionic liquids, which are good electrolytes, are studied for their potential to improve the ionic conductivity and thermal stability of fuel cell applications. This review summarizes the development and evolution of CS biopolymer-based membranes and ionic liquids in fuel cell applications over the past decade. It also focuses on the improved performances of fuel cell applications using biopolymer-based membranes and ionic liquids as promising clean energy.

Subacute Thyroiditis-An Often Overlooked Sonographic Diagnosis: Report of 3 Cases.

The characteristic sonographic finding of subacute thyroiditis of a heterogeneous poorly defined hypoechoic area in the thyroid gland may mimic that of thyroid malignancy. This finding needs to be interpreted in the correct clinical context to avoid an unnecessary biopsy. We describe 3 patients who underwent thyroid biopsy on the basis of suspicious sonographic findings but who subsequently had a diagnosis of subacute thyroiditis.

Gender, Race, and Age at Diagnosis as Risk Factors for Metastasis or Recurrence among 1,657 Thyroid Cancer Patients Treated with Radioiodine across 40 Years in Singapore.

BACKGROUND: To obtain descriptive data on Singaporean thyroid cancer patients treated with radioiodine and to assess gender, race, and age at diagnosis as risk factors for metastasis or recurrence. METHODS: This is a retrospective study of all thyroid cancer patients treated with radioiodine of any prescribed activity at our institution. Data collected included: age at diagnosis, gender, race, histopathological type, duration of follow-up, and metastasis at diagnosis (locoregional or distant) or recurrence at any time. Gender, race, and age at diagnosis were analyzed for possible associations with metastasis or recurrence. RESULTS: A total of 1,657 thyroid cancer patients were treated with radioiodine across a 40-year period; mean follow-up 6.4 ± 6.9 years (median 4.2 years). 656 (39.6%) patients had metastasis or recurrence over the duration of their follow-up. Male gender (odds ratio (OR) 1.38; p = 0.006), Malay race (OR 1.71; p < 0.0001), and age at diagnosis of > 46 years (OR 1.31; p = 0.007) were significantly associated with metastasis or recurrence. CONCLUSION: Male gender, Malay race, and age at diagnosis of > 46 years were significant risk factors for metastasis or recurrence in Singaporean thyroid cancer patients treated with radioiodine.

Post-thyroidectomy neck ultrasonography in patients with thyroid cancer and a review of the literature.

The importance of routine neck ultrasonography for the detection of unsuspected local or nodal recurrence of thyroid cancer following thyroidectomy (with or without neck dissection) is well documented in many journal articles and international guidelines. Herein, we present a pictorial summary of the sonographic features of benign and malignant central neck compartment nodules and cervical lymph nodes via a series of high-quality ultrasonographic images, with a review of the literature.

Unusual presentation of extraosseous metastases on bone scintigraphy.

Osteosarcoma metastases frequently occur in the lungs or the skeleton. Bone scans play an important role in disease staging by identifying other skip areas of skeletal involvement as well as extraosseous metastases. We report a case of aggressive osteosarcoma, with bone metastases and extraosseous areas of involvement in the lungs, distant lymph nodes, and peritoneal and subcutaneous metastasis seen in a preoperative Tc-99m methylene diphosphonate bone scan. These findings were confirmed with histology and correlative cross-sectional imaging.

Promising role of [18F] fluorocholine PET/CT vs [18F] fluorodeoxyglucose PET/CT in primary brain tumors-early experience.

Primary brain tumors (PBT), in particular gliomas, are among the most difficult neoplasms to treat, necessitating good quality imaging to guide clinicians at many junctures. Current imaging modalities, including [18F] fluorodeoxyglucose (FDG) PET/CT, MRI and MR spectroscopy (MRS), have various limitations, particularly with regard to differentiating tumor from radiation induced necrosis (RIN) and from normal cerebral metabolic uptake. [18F] fluorocholine (FCH) is an analog of choline with potentially optimal imaging characteristics, as pharmacokinetic studies with FCH conducted in patients showed minimal FCH uptake by normal brain parenchyma, whereas high-grade tumors are known to have increased choline uptake. We present two cases of our early experience with FCH PET/CT for patients with PBT and discuss the potential use and comparative limitations of this imaging modality.

Smart garment for trunk posture monitoring: A preliminary study.

BACKGROUND: Poor postures of the spine have been considered in association with a number of spinal musculoskeletal disorders, including structural deformity of the spine and back pain. Improper posturing for the patients with spinal disorders may further deteriorate their pain and deformities. Therefore, posture training has been proposed and its rationale is to use the patient's own back muscles to keep the spine within the natural curvature. A posture training device may help to facilitate this therapeutic approach by providing continuous posture monitoring and feedback signals to the patient when "poor" posture is detected. In addition, the users of the device may learn good postural habits that could carry over into their whole life. METHODS: A smart garment with integrated accelerometers and gyroscopes, which can detect postural changes in terms of curvature variation of the spine in the sagittal and coronal planes, has been developed with intention to facilitate posture training. The smart garment was evaluated in laboratory tests and with 5 normal subjects during their daily activities. RESULTS: Laboratory tests verified that the accuracy of the system is < 1 degrees and < 1.5 degrees in static and dynamic tilting measurements respectively. The results showed that the smart garment could facilitate subjects to prevent prolonged poor postures of the spine, especially the posture of the lumbar spine in which at least 40% of the time in poor posture were reduced. CONCLUSION: The smart garment has been developed to be a portable and user-friendly trunk posture monitoring system and it could be used for collection of the trunk posture information and provision of instant feedback to the user if necessary for posture training purpose. The current pilot study demonstrated that the posture of normal subjects could be monitored and trained via this smart garment. With further clinical investigations, this system could be considered in some flexible spinal deformities such as scoliosis and kyphosis.