Novel SrO-Containing Glass-Ceramic Sealants for Solid Oxide Electrolysis Cells (SOEC): Their Design and Characterization under Relevant Conditions.

This study presents results on the development of strontium oxide (SrO) containing glass sealants used to join Crofer22APU to yttria-stabilized zirconia (3YSZ), in which the main glass components, that is, silicon oxide (SiO2), strontium oxide (SrO), calcium oxide (CaO) and aluminum oxide (Al2O3), have been varied appropriately. Certain properties, such as the crystallization behavior, the coefficient of thermal expansion, adhesion, and reactivity of the sealants in contact with Crofer22APU, have been reviewed and discussed. The optimized glass composition (with CTE in the 9.8-10.3 × 10-6 K-1 range) results in a good joining behavior by hindering the formation of undesirable strontium chromate (SrCrO4) on contact with the Crofer22APU steel after 1000 h. at 850 °C. High specific resistivity values of about 106 Ohm.cm have been obtained, thus demonstrating good insulating properties at 850 °C under an applied voltage of 1.6 V. A negligible degradation in the electrical resistivity trend was measured during the test up to 1000 h, thus excluding the presence of detrimental reactions of the glass-ceramic sealant in contact with Crofer22APU under a dual atmosphere, as confirmed using SEM-EDS post-mortem analyses.

Structural Model for Transient Pt Oxidation during Fuel Cell Start-up Using Electrochemical X-ray Photoelectron Spectroscopy.

Potential spikes during the start-up and shutdown of fuel cells are a major cause of platinum electrocatalyst degradation, which limits the lifetime of the device. The electrochemical oxidation of platinum (Pt) that occurs on the cathode during the potential spikes plays a key role in this degradation process. However, the composition of the oxide species formed as well as their role in catalyst dissolution remains unclear. In this study, we employ a special arrangement of XPS (X-ray photoelectron spectroscopy), in which the platinum electrocatalyst is covered by a graphene spectroscopy window, making the in situ examination of the oxidation/reduction reaction under wet conditions possible. We use this assembly to investigate the change in the oxidation states of Pt within the potential window relevant to fuel cell operation. We show that above 1.1 VRHE (potential vs reversible hydrogen electrode), a mixed Ptδ+/Pt2+/Pt4+ surface oxide is formed, with an average oxidation state that gradually increases as the potential is increased. By comparing a model based on the XPS data to the oxidation charge measured during potential spikes, we show that our description of Pt oxidation is also valid during the transient conditions of fuel cell start-up and shutdown. This is due to the rapid Pt oxidation kinetics during the pulses. As a result of the irreversibility of Pt oxidation, some remnants of oxidized Pt remain at typical fuel cell operating potentials after a pulse.

Facile synthesis, spectroscopic evaluation and antimicrobial screening of metal endowed triazole compounds.

The scientific interest in developing new complexes as inhibitors of bacterial biofilm related infections is constantly rising. The present work describes the chemical synthesis, structural and biological scrutiny of a triazole Schiff base ligand and its corresponding complexes. Triazole Schiff base, (2-methoxy-4-[(1H-1,2,4-triazol-3-ylimino)methyl]phenol) was synthesized from the condensation reaction of 3-amino-1,2,4-triazole and 4-hydroxy-3-methoxybenzaldehyde in an equimolar ratio. The triazole ligand (H2L) was characterized by physical (solubility, color, melting point), spectroscopic [UV-visible (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR) and mass spectra (MS)] and micro analysis to evaluate their elemental composition. The bidentate ligand was complexed with transition metal [VO(IV), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] in 1:2 molar ratio. The complexes were characterized by physical (color, solubility, decomposition temperature, conductance and magnetic moment), FT-IR, UV-Vis and elemental analysis. Thermal stability and fluorescence properties of the compounds were also determined. Density functional theory based theoretical calculations were accomplished to gain more insight into spectroscopic properties. The frontier molecular orbital analysis revealed that the ligand was less reactive with reduced electron donating capability and more kinetic stability than complexes. The as-synthesized compounds were scrutinized for anti-bacterial and anti-fungal activity against selected strains. Cobalt complex exhibited highest antibacterial activity against Escherichia coli and nickel complex has shown highest antifungal activity against Aspergillus niger. All the compounds also showed good antioxidant activity. The theoretical results reflect consistency with the experimental findings signifying that such compounds could be the promising chemical scaffolds in the near future against microbial infectious.

Synthesis of mesoporous carbon spheres via a soft-template route for catalyst supports in PEMFC cathodes.

Synthesis of carbon spheres via a soft-template route should be further improved for industrial applications especially in terms of time, cost and scalability. The present work reports on the relatively fast production of mesoporous carbon via an ammonia-catalyzed hydrothermal soft-template one-pot route denoted as CFAH with m-aminophenol as the carbon source and triblock copolymer Pluronic® F127 as the template. For comparison, an acidic route with resol as the carbon precursor (CFRH) was evaluated as well. The best results regarding particle size and pore distribution of the as-prepared CFRH and CFAH samples were obtained in 2 M HCl and 6 M NH4OH at 120 °C for 12 h and 700 °C pyrolysis temperature, respectively. GDE with CFRH and CFAH supported platinum showed excellent ECSA retention of about 60-70% during accelerated degradation testing under half-cell conditions compared to only 13% for GDE with Pt/CVulcan reference material.

Two-Stage Flexor Tendon Reconstruction in Zone II Using Paediatric Silicon Catheter at Mayo Hospital Lahore: A Case Series.

The aim of the study was to assess the functional outcomes after two stage flexor tendon reconstruction in zone II tendon injury of the hand using paediatric silicon catheter. A prospective case series of total 22 digits of 21 patients having Boyes grades I, II and III neglected flexor tendon injury, for a mean time of 10 months since injury were included. Two stage reconstructive procedure was performed. A final follow-up was done at one year to assess the functional outcome using Buck-Gramcko scale. Out of 22 digits, there were 06 (27.27%) Boyes grades I digits, 11 (50%) grades II and 5 (22.72%) grades III. At final follow-up thirteen (59.09%) digits had excellent, five (22.72%) had good while three (13.63%) had satisfactory result and one (4.54%) had poor result. We concluded that two stage flexor tendon reconstruction using silicon catheter yields good results and is cost effective.

Selective Adsorption and Photocatalytic Degradation of Extracellular Antibiotic Resistance Genes by Molecularly-Imprinted Graphitic Carbon Nitride.

There is a growing need to mitigate the discharge of extracellular antibiotic resistance genes (ARGs) from municipal wastewater treatment systems. Here, molecularly-imprinted graphitic carbon nitride (MIP-C3N4) nanosheets were synthesized for selective photocatalytic degradation of a plasmid-encoded ARG (blaNDM-1, coding for multidrug resistance New Delhi metallo-ß-lactamase-1) in secondary effluent. Molecular imprinting with guanine enhanced ARG adsorption, which improved the utilization of photogenerated oxidizing species to degrade blaNDM-1 rather than being scavenged by background nontarget constituents. Consequently, photocatalytic removal of blaNDM-1 in secondary effluent with MIP-C3N4 (k = 0.111 ± 0.028 min-1) was 37 times faster than with bare graphitic carbon nitride (k = 0.003 ± 0.001 min-1) under UVA irradiation (365 nm, 3.64 × 10-6 Einstein/L·s). MIP-C3N4 can efficiently catalyze the fragmentation of blaNDM-1, which decreased the potential for ARG repair by transformed bacteria. Molecular imprinting also changed the primary degradation pathway; electron holes (h+) were the predominant oxidizing species responsible for blaNDM-1 removal with MIP-C3N4 versus free radicals (i.e., ·OH and O2-) for coated but nonimprinted C3N4. Overall, MIP-C3N4 efficiently removed blaNDM-1 from secondary effluent, demonstrating the potential for molecular imprinting to enhance the selectivity and efficacy of photocatalytic processes to mitigate dissemination of antibiotic resistance from sewage treatment systems.

Discerning the inefficacy of hydroxyl radicals during perfluorooctanoic acid degradation.

Perfluorooctanoic acid (PFOA) is a recalcitrant contaminant of emerging concern, and there is growing interest in advanced oxidation processes to degrade it. However, there is ambiguity in the literature about the efficacy of hydroxyl radicals (OH) for degrading PFOA. Here, we resolve this controversy by comparing PFOA degradation by UV photolysis (254 nm, 6 × 10-6 E/L.s) versus UV + H2O2, which produces OH. We optimized OH production in a UV + H2O2 system using nitrobenzene (NB) as a OH probe, but even under optimized conditions (i.e., 5 g/L H2O2), no significant difference occurred in PFOA removal by UV photolysis (21.1 ± 0.4%) versus UV + H2O2 (19.7 ± 0.7%) after 1-day treatment. Both treatments also resulted in similar daughter by-product concentrations and defluorination efficiencies (9.5 ± 1.7% for UV photolysis and 6.8 ± 1.0% for UV + H2O2), which indicates that OH is ineffective towards PFOA degradation and infers that other degradation mechanisms that are independent of OH production should be explored.

Uremic Pruritus: Prevalence and Impact on Quality of Life and Depressive Symptoms in Hemodialysis Patients.

Background End-stage renal disease (ESRD) is a major public health problem with many associated symptoms. Uremic pruritus (UP) develops in 40% of patients on hemodialysis and has major effects on the patient's life. It is also an independent risk factor for increased mortality, and its psychiatric implications remain poorly characterized in our local setup, where it tends to be underdiagnosed and undertreated. Objectives and rationale The study aims to report the prevalence of uremic pruritus in our study population and associate it with various patient parameters, which may define a subset of patients at high risk for this pruritus. We also assess the effects of uremic pruritus on the patient's quality of life (by using the Dermatology Life Quality Index; DLQI) and depressive symptoms (by using the Public Health Questionnaire; PHQ-9). Materials and methods It was a descriptive, cross-sectional study conducted in the nephrology unit of the multi-organ failure (MOF) center of the Holy Family Hospital (HFH), Rawalpindi, Pakistan, from February 2019 to June 2019, during which 173 male patients on hemodialysis were selected. Informed consent was taken from patients and other skin-related causes of pruritis were excluded. Uremic pruritus was defined as pruritis lasting for at least three months after the onset of ESRD. The 5-D, PHQ-9, and DLQI questionnaires were used to assess pruritis, depressive symptoms, and quality of life, respectively. Their Cronbach's Alpha values for 73 responses were 0.83, 0.81, and 0.71, respectively. The descriptive analysis was performed using SPSS v23.0 (IBM Corp, Armonk, NY, US). Spearman's rank-order correlation, independent samples t-test, and one-way analysis of variance (ANOVA) were used to analyze study variables. Results The prevalence of uremic pruritus was 49.1%, with many patients having generalized itching. Unemployment and longer disease duration predisposed the patients towards uremic pruritus, as the mean 5-D score in this subset were greater (p<0.05 in the independent samples t-test). The results of one-way ANOVA were significant (p<0.05), indicating higher 5-D scores in worsening categories of depressive symptoms and quality of life. Spearman's correlation matrix showed that 5-D, PHQ-9, and DLQI scores were strongly correlated with each other. Conclusions The prevalence of uremic pruritus among male hemodialysis patients is high, at 49.1%. It significantly contributes to depressive symptoms and a lower quality of life, which are associated with worse prognosis in hemodialysis patients. Thus, a clinician must keep in mind the psychiatric implications of uremic pruritus and treat it effectively to optimize the patient's medical care.

Association of Physical Activity and Sleep Quality with Academic Performance Among Fourth-year MBBS Students of Rawalpindi Medical University.

Background Medical students face greater academic stress and devote more time to their studies due to the tough nature of medical education, at the cost of sleep and physical activity. Good sleep quality and physical activity improve the mental ability and academic performance of the students. Objectives and rationale The study aims to assess sleep quality and physical activity levels among fourth-year MBBS students of Rawalpindi Medical University. We compare these levels with gender and boarding status and correlate them with the academic performance of the students. This may provide new target areas to improve the academics of students performing below average. Materials and methods It was a descriptive, cross-sectional study conducted in March 2019 on 344 medical students enrolled in the fourth-year MBBS class of Rawalpindi Medical University. Sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI), physical activity levels by the Global Physical Activity Questionnaire (GPAQ), and academic performance by the marks attained in the most recent pathology class test. The students who could not prepare for the test in the usual manner were excluded from the study. Two-hundred nineteen (219) students were part of the final study sample. Data analysis was performed using SPSS v.22.0 (IBM Corp, Armonk, NY, US). A chi-squared test, independent samples t-test, Pearson's correlation, and a multiple linear regression model were used to assess the variables. Results Sleep quality and physical activity were significantly correlated with academic performance (p-values of the chi-square and t-test were <0.000). Pearson's correlation coefficient was -0.69 for PSQI (p<0.000) and 0.62 for GPAQ (p 0.003) with test scores. Gender showed significant association with sleep and physical activity levels (male students had better physical activity level and poorer sleep quality than female students) but no association with test scores. Boarding status was significantly associated with all three variables. Boarders had lower mean test scores and poorer sleep and physical activity indices as compared to non-boarders. The multiple linear regression model was valid (p-value of the F test was <0.000), with beta coefficients of -2.53 ( p=0.002) for sleep quality and 1.37 (p=0.01) for physical activity. The R2 value was 0.84 (84%). Conclusions Our study indicates an overall poor sleep quality and physical activity level among fourth-year medical students, particularly boarding students, who have lower test scores and worse sleep and physical activity levels. In general, male students have better GPAQ scores and female students have better PSQI scores. Both the PSQI and GPAQ scores are significantly correlated with test scores and provide potential target areas to improve the exam performance of the students.

Shear Performance at Room and High Temperatures of Glass⁻Ceramic Sealants for Solid Oxide Electrolysis Cell Technology.

To provide a reliable integration of components within a solid oxide electrolysis cell stack, it is fundamental to evaluate the mechanical properties of the glass⁻ceramic sealing materials, as well as the stability of the metal⁻glass⁻ceramic interface. In this work, the mechanical behavior of two previously developed glass⁻ceramic sealants joined to Crofer22APU steel is investigated at room temperature, 650 °C, and 850 °C under shear load. The mechanical properties of both the glass⁻ceramics showed temperature dependence. The shear strength of Crofer22APU/glass⁻ceramic/Crofer22APU joints ranged from 14.1 MPa (20 °C) to 1.8 MPa (850 °C). The elastic modulus of both glass⁻ceramics also reduced with temperature. The volume fraction of the crystalline phases in the glass⁻ceramics was the key factor for controlling the mechanical properties and fracture, especially above the glass-transition temperature.

Increased trend of unnecessary use of radiological diagnostic modalities in Pakistan: radiologists perspective.

BACKGROUND: Over the past few years, a significant overuse of radiological investigations influenced the quality and cost of healthcare of the country as it may lead to non-compliance of the patient due to non-affordability and also may harm the patient in terms of radiation hazards. Pakistan, being a low-income, resource-constraint country, is facing financial impact on families as well as health system due to multiple reasons. OBJECTIVES: The purpose of study is to identify reasons of unnecessary use of radiological diagnostic modalities in Pakistani hospitals as perceived by radiologists. METHODS: A cross-sectional study was conducted on a total of all 105 radiologists, having at least 1 year experience of working in radiology, working in five tertiary care hospitals in Lahore. A self-constructed, self-administered, pretested 5-point Likert scale opinion-based questionnaire was administered after taking informed consent. It includes questions about excessive radiological use that may be attributed to the physicians, investigations, patients and other non-categorized causes. Results were analyzed using SPSS version 23. RESULTS: Since the assessment forms were handed over and collected from the radiologists in person, the response rate was 100%. Of a total of 105 respondents, 78 (74.28%) respondentsagreed that there is an actual increase, 25 (23.80%) respondents disagreed and 2 (1.90%) respondents were unsure. Most important reasons for increased usage of radiological investigations are 'need of accuracy of diagnosis' (P = 0.009), 'trend of physicians to repeat tests in order to confirm preset diagnoses' (P-value = 0.03), 'lack of knowledge about proper usage of radiological advances' (P-value = 0.005) and 'lack of proper clinical examination' (P-value = 0.04). CONCLUSION: Unnecessary use of radiological investigations is actually there as perceived by radiologists, which is attributed to inadequate knowledge, attitude and training of physicians to refer patients to radiological resources. This research can be a stepping stone for future researchers as it can be used for elaborating these causes individually and finding ways as to how each of these causes can be controlled and minimized to bring about a decline in excessive usage of these modalities for the betterment of the patients.

Easily Recoverable, Micrometer-Sized TiO2 Hierarchical Spheres Decorated with Cyclodextrin for Enhanced Photocatalytic Degradation of Organic Micropollutants.

Micrometer-sized titanium dioxide hierarchical spheres (TiO2-HS) were assembled from nanosheets to address two common limitations of photocatalytic water treatment: (1) inefficiency associated with scavenging of oxidation capacity by nontarget water constituents and (2) energy-intensive separation and recovery of the photocatalyst slurry. These micrometer-sized spheres are amenable to low-energy separation, and over 99% were recaptured from both batch and continuous flow reactors using microfiltration. Using nanosheets as building blocks resulted in a large specific surface area-3 times larger than that of commercially available TiO2 powder (Evonik P25). Anchoring food-grade cyclodextrin onto TiO2-HS (i.e., CD-TiO2-HS) provided hydrophobic cavities to entrap organic contaminants for more effective utilization of photocatalytically generated reactive oxygen species. CD-TiO2-HS removed over 99% of various contaminants with dissimilar hydrophobicity (i.e., bisphenol A, bisphenol S, 2-naphthol, and 2,4-dichlorophenol) within 2 h under a low-intensity UVA input (3.64 × 10-6 einstein/L/s). As with other catalyst (including TiO2 slurry), periodic replacement or replenishment would be needed to maintain high treatment efficiency (e.g., we demonstrate full reactivation through simple reanchoring of CD). Nevertheless, this task would be offset by significant savings in photocatalyst separation. Thus, CD-TiO2-HS is an attractive candidate for photocatalytic water and wastewater treatment of recalcitrant organic pollutants.

Porous Electrospun Fibers Embedding TiO2 for Adsorption and Photocatalytic Degradation of Water Pollutants.

Using a bipolymer system consisting of polyvinylpyrrolidone (PVP) and poly(vinylidene fluoride) (PVDF), P25-TiO2 was immobilized into thin film mats of porous electrospun fibers. Pores were introduced by dissolving sacrificial PVP to increase surface area and enhance access to TiO2. The highest photocatalytic activity was achieved using a PVDF:PVP weight ratio of 2:1. Methylene blue (MB) was used to visualize contaminant removal, assess the sorption capacity (5.93 ± 0.23 mg/g) and demonstrate stable removal kinetics ( kMB > 0.045 min-1) under UVA irradiation (3.64 × 10-9 einstein/cm2/s) over 10 cycles. Treatment was also accomplished via sequential MB sorption in the dark and subsequent photocatalytic degradation under UVA irradiation, to illustrate that these processes could be uncoupled to overcome limited light penetration. The photocatalytic mat degraded bisphenol A and 17α-ethynylestradiol in secondary wastewater effluent (17 mg TOC/L), and (relative to TiO2 slurry) immobilization of TiO2 in the mat mitigated performance inhibition by co-occurring organics that scavenge oxidation capacity. This significantly lowered the electrical energy-per-order of reaction (EEO) needed to remove such endocrine disruptors in the presence of oxidant scavenging/inhibitory organics. Thus, effective TiO2 immobilization into polymers with affinity toward specific priority pollutants could both increase the efficiency and reduce energy requirements of photocatalytic water treatment.

Visual outcome and complications after removal of posterior segment intraocular foreign bodies through pars plana approach.

OBJECTIVE: To assess the visual outcome and complications after removal of posterior segment retained intraocular foreign bodies through pars plana approach. STUDY DESIGN: Case series. PLACE AND DURATION OF STUDY: Department of Ophthalmology, Jinnah Postgraduate Medical Centre, Karachi, from May 2005 to May 2006. METHODOLOGY: Fifty patients with history of ocular foreign body were admitted through outpatient department and emergency. History, visual acuity, ocular and general examination was done. The foreign body was localized with the radiograph of the skull and ultrasonography. Primary repair was done in patients with open wounds. Pars plana vitrectomy, magnetic or forceps extraction of foreign body was done as required visual outcomes and complications were noted. RESULTS: Among the 50 patients, there were 45 (90%) males and 5 (10%) females. Average age of the patients was 31.52 +9.52 (ranging from 20 to 50) years. The pre-operatively visual acuity finger counting to perception of light was 78% cases. The best corrected final visual acuity was 6/6 in 1 (2%) patient, 6/9 in 5 (10%) patients, 6/12 in 5 (10%) patients, 6/18 in 3 (6%) patients, 6/24 and 6/36 in 4 (8%) patients each, 6/60 in 4 (8%) patients, finger counting in 8 (16%) patients, hand movement in 4 (8%) patients, projection of light in 9 (18%) patients and no projection of light in 3 (6%) patients. The postoperative complications were corneal opacity in 8 (16%) patients, anterior chamber inflammatory reaction in 6 (12%) patients, increased intraocular pressure in 1 (2%) patient, silicone oil in anterior chamber in 1 (2%) patient, macular scar in 7 (14%) patients, cystoid macular edema in 1 (2%) patient, endophthalmitis in 4 (8%) patients, retinal detachment in 11 (22%) patients and phthisis bulbi in 3 (6%) patients. CONCLUSION: Acceptable visual results were achieved after the removal of posterior segment intraocular foreign bodies by vitrectomy. However, multiple complications can be encountered which require meticulate postoperative care.

Analysis of primary benign orbital lesions / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To study the pattern of presentation and to highlight the common causes of primary benign orbital lesions.of Jinnah Postgraduate Medical Centre Karachi from July 1997 to August 2001 and then from September 2001 to date (Continued) at the Department of Ophthalmology of Chandka Medical College & Hospital Larkana. Only patients with primary benign orbital lesions were included in this study. All the patients were admitted in eye ward from the out patients department. The diagnosis of the disease was based on the presentation, clinical examination, investigations and histopathology of excised mass. A total of 68 patients were included in this study. The age range was from 2 months to 60 years. Out of 68, 27 (39.7%) patients were male and 41 (60.3%) were female. The left orbit was involved in 35 (51.5%) and right orbit was involved in 33 (48.5%).revealed that superficial capillary hemangiomas of the eye lid were the most common lesion 26 (38.2%) followed by deep orbital cavernous hemangiomas 5 (7.4%), lymphangiomas 5 (7.4%), orbital varices 4 (5.9%), gliomas 7 (10.3%), meningiomas 5 (7.4%), neurofibromas 5 (7.4%), neurofibromatosis 4 (5.9%), schwannomas 2 (2.9%), and pleomorphic adenoma (benign mixed cell tumor) of lacrimal gland 5 (7.4%) cases.treatment can prevent the patient from visual and life threatening complications.