Spin-related Cu-Co pair to increase electrochemical ammonia generation on high-entropy oxides

The electrochemical conversion of nitrate to ammonia is a way to eliminate nitrate pollutant in water. Cu-Co synergistic effect was found to produce excellent performance in ammonia generation. However, few studies have focused on this effect in high-entropy oxides. Here, we report the spin-related Cu-Co synergistic effect on electrochemical nitrate-to-ammonia conversion using high-entropy oxide Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O. In contrast, the Li-incorporated MgCoNiCuZnO exhibits inferior performance. By correlating the electronic structure, we found that the Co spin states are crucial for the Cu-Co synergistic effect for ammonia generation. The Cu-Co pair with a high spin Co in Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O can facilitate ammonia generation, while a low spin Co in Li-incorporated MgCoNiCuZnO decreases the Cu-Co synergistic effect on ammonia generation. These findings offer important insights in employing the synergistic effect and spin states inside for selective catalysis. It also indicates the generality of the magnetic effect in ammonia synthesis between electrocatalysis and thermal catalysis.

Development of a novel questionnaire to assess knowledge, attitude and practice towards medical disorders in pregnancy among clinicians

INTRODUCTION

Maternal medicine is important and complex. It focuses on the care of mothers with comorbidities or medical disorders during pregnancy. To date, there are limited tools to assess clinicians' knowledge, attitude and practice (KAP) in this field.

MATERIALS AND METHODS

This study aims to develop and validate a questionnaire measuring the KAP of clinicians towards maternal medicine. Literature reviews, item generation and multiple experts' reviews were conducted during the questionnaire development phase. Convenient sampling was undertaken for this cross-sectional survey. A total of 168 clinicians from one tertiary hospital and three health clinics participated in thepilot testing using the modified questionnaire. In addition, test-retest was performed on 30 participants to examine its reliability, whilst exploratory factor analysis (EFA) was undertaken to determine its construct validity.

RESULTS

This finalised questionnaire contained 36 items with excellent content validity. Pertaining to test-retest reliability, all knowledge domain items showed Kappa values > 0.20, except item K29; attitude domain items overall Cronbach's alpha was 0.787 with corrected item-total correlation > 0.300 and lastly, all items in practice domain achieved intra-class correlation index > 0.700, except P2.5. EFA supported four factor structures, but six items were removed due to the following reasons: cross loading, negative or poor loading factor (< 0.3).

CONCLUSION

Overall, this instrument has an acceptable psychometric property, content validity, internal reliability and construct validity. It is hope that this questionnaire would be validated in other populations and be used in future research to enrich our understanding of clinicians' KAP towards maternal medicine.

First principles-based design of lightweight high entropy alloys

Recently, the design of lightweight high entropy alloys (HEAs) with a mass density lower than 5 g/cm3 has attracted much research interest in structural materials. We applied a first principles-based high-throughput method to design lightweight HEAs in single solid-solution phase. Three lightweight quinary HEA families were studied: AlBeMgTiLi, AlBeMgTiSi and AlBeMgTiCu. By comprehensively exploring their entire compositional spaces, we identified the most promising compositions according to the following design criteria: the highest stability, lowest mass density, largest elastic modulus and specific stiffness, along with highest Pugh's ratio. We found that HEAs with the topmost compositions exhibit a negative formation energy, a low density and high specific Young's modulus, but a low Pugh's ratio. Importantly, we show that the most stable composition, Al0.31Be0.15Mg0.14Ti0.05Si0.35 is energetically more stable than its metallic compounds and it significantly outperforms the current lightweight engineering alloys such as the 7075 Al alloy. These results suggest that the designed lightweight HEAs can be energetically more stable, lighter, and stiffer but slightly less ductile compared to existing Al alloys. Similar conclusions can be also drawn for the AlBeMgTiLi and AlBeMgTiCu. Our design methodology and findings serve as a valuable tool and guidance for the experimental development of lightweight HEAs.

Antifungal susceptibility profile and biofilm-producing capability of Candida tropicalis isolates in a tertiary medical centre

BACKGROUND

Candida tropicalis is a globally distributed yeast that has been popping up in the medical literature lately, albeit for unenviable reasons. C. tropicalis is associated with substantial morbidity, mortality as well as drug resistance. The aims of this study were to ascertain the antifungal susceptibility profile and the biofilm-producing capability of this notorious yeast in our centre.

METHODS

C. tropicalis isolates from sterile specimens were collected over a 12-month period. Conclusive identification was achieved biochemically with the ID 32 C kit. Susceptibility to nine antifungal agents was carried out using the colourimetric broth microdilution kit Sensititre YeastOne YO10. Biofilm-producing capability was evaluated by quantifying biomass formation spectrophotometrically following staining with crystal violet.

RESULTS

Twenty-four non-repetitive isolates of C. tropicalis were collected. The resistance rates to the triazole agents were 29.2% for fluconazole, 16.7% for itraconazole, 20.8% for voriconazole and 8.3% for posaconazole-the pan-azole resistance rate was identical to that of posaconazole. No resistance was recorded for amphotericin B, flucysosine or any of the echinocandins tested. A total of 16/24 (66.7%) isolates were categorized as high biomass producers and 8/24 (33.3%) were moderate biomass producers. None of our isolates were low biomass producers.

CONCLUSION

The C. tropicalis isolates from our centre were resistant only to triazole agents, with the highest resistance rate being recorded for fluconazole and the lowest for posaconazole. While this is not by itself alarming, the fact that our isolates were prolific biofilm producers means that even azole-susceptible isolates can be paradoxically refractory to antifungal therapy.

Pulmonary thromboembolic disease associated with COVID-19 infection: a comparison between geriatric and non-geriatric populations

INTRODUCTION

The magnitude of Coronavirus Disease 2019 (COVID-19) infection among the elderly population is expected to rise. Our study compares the clinical and computed tomographical (CT) features of pulmonary thromboembolic (PTE) disease associated with COVID-19 infection in geriatric and non-geriatric cases, and explores the 60-day mortality rate in these two groups.

MATERIALS AND METHODS

We conducted this retrospective cross-sectional study in Hospital Tengku Ampuan Rahimah, Selangor, Malaysia. Patients admitted in April 2021 and May 2021 with concomitant COVID-19 infection and PTE disease were included. Demographic, clinical and laboratory data were retrieved, whilst CTPA images were analysed by a senior radiologist.

RESULTS

A total of 150 patients were recruited, comprising 45 geriatric patients and 105 non-geriatric patients. The prevalence rate of hypertension, diabetes mellitus and dyslipidaemia were higher among the geriatric cohort. Evidently, the percentage of patients with fever and diarrhoea were significantly higher among the non-geriatric cohort. The geriatric cohort also recorded a significantly lower absolute lymphocyte count at presentation and albumin level during admission. Despite earlier presentation, the geriatric cohort suffered from more severe diseases. Analysis of the CT features demonstrated that the most proximal pulmonary thrombosis specifically limited to the segmental and subsegmental pulmonary arteries in both cohorts. The elderly suffered from a significantly higher inhospital mortality rate and their cumulative probability of survival was significantly lower.

CONCLUSION

Typical COVID-19 symptoms may be absent among the elderly, prompting a lower threshold of suspicion during the COVID-19 pandemic. Additionally, the elderly demonstrated a higher probability of adverse outcomes despite earlier presentation and treatment.

Evaluation of mean neutrophil volume and immature to total neutrophil ratio as a biomarker for bacterial sepsis in adult patients

INTRODUCTION

Mean neutrophil volume (MNV) and immature to total neutrophil ratio (IT Ratio) has been found to support the detection of sepsis in elderly and neonates. This study aimed to assess the diagnostic significance of MNV and IT ratio in adult sepsis population.

MATERIALS AND METHODS

Sixty-four adult patients presented with suspected bacterial sepsis were included in this study. Relevant cultures and/or pertinent serology tests were performed. Full blood counts were analysed for MNV and IT ratio.

RESULTS

Fifty-one patients out of 64 recruited subjects were confirmed sepsis. Twentyfour patients had confirmed bacterial infection by cultivation and two were positive for leptospiral serology. MNV was very good in distinguishing sepsis from non-sepsis group (AUC = 0.80, 95% confidence interval (CI) = 0.69-0.91, Accuracy = 0.72, Kappa = 0.40) with a cut-off value of 153.5 (sensitivity = 67%, specificity = 92%). There was no significant difference in IT ratio between sepsis and non-sepsis group (p-value > 0.05). MNV was superior over IT ratio (AUC = 0.85, 95%CI = 0.76-0.95, and AUC = 0.70, 95% CI = 0.56-0.85, respectively) in diagnosing bacterial infection. The optimum cut-off value for MNV in bacterial infection was 154.5 (sensitivity = 67%, specificity = 89%) and for IT ratio was 0.035 (sensitivity = 45%, specificity = 67%).

CONCLUSION

MNV appears to be a very good marker for diagnosing sepsis and bacterial infection. We recommend including MNV into sepsis workup in ED setting, since it can be determined without additional specimen.

Factors related to prehospital delay and decision delay among acute stroke patients in a district hospital, Malaysia

INTRODUCTION

Time is the greatest challenge in stroke management. This study aimed to examine factors contributing to prehospital delay and decision delay among stroke patients.

MATERIALS AND METHODS

A cross-sectional study involving acute stroke patients admitted to Seri Manjung Hospital was conducted between August 2019 and October 2020 via faceto- face interview. Prehospital delay was defined as more than 120 minutes taken from recognition of stroke symptoms till arrival in hospital, while decision delay was defined as more than 60 minutes taken from recognition of stroke symptoms till decision was made to seek treatment.

RESULTS

The median prehospital delay of 102 enrolled patients was 364 minutes (IQR 151.5, 1134.3) while the median for decision delay was 120 minutes (IQR 30.0, 675.0). No history of stroke (adj. OR 4.15; 95% CI 1.21, 14.25; p=0.024) and unaware of thrombolysis service (adj. OR 17.12; 95% CI 1.28, 229.17; p=0.032) were associated with higher odds of prehospital delay, while Indian ethnicity (adj. OR 0.09; 95% CI 0.02, 0.52; p=0.007) was associated with lower odds of prehospital delay as compared to Malay ethnicity. On the other hand, higher National Institutes of Health Stroke Scale (NIHSS) score (adj. OR 0.86; 95% CI 0.78, 0.95; p=0.002) was associated with lower odds of decision delay.

CONCLUSION

Public awareness is crucial to shorten prehosital delay and decision delay for better patients' outcomes in stroke. Various public health campaigns are needed to improve the awareness for stroke.

Clinical characteristics and computed tomographical features of pulmonary thromboembolic disease associated with COVID-19 infection: A tertiary hospital analysis

INTRODUCTION

The co-existence of coronavirus disease 2019 (COVID-19) and pulmonary thromboembolic (PTE) disease poses a great clinical challenge. To date, few researches have addressed this important clinical issue among the South-East Asian populations. The objectives of this study were as follow: (1) to describe the clinical characteristics and computed tomographical (CT) features of patients with PTE disease associated with COVID-19 infection and (2) to compare these parameters with those COVID-19 patients without PTE disease.

MATERIALS AND METHODS

This cross-sectional study with retrospective record review was conducted in Hospital Tengku Ampuan Rahimah, Selangor, Malaysia. We included all hospitalised patients with confirmed COVID-19 infection who had undergone CT pulmonary angiogram (CTPA) examinations for suspected PTE disease between April 2021 and May 2021. Clinical data and laboratory data were extracted by trained data collectors, whilst CT images retrieved were analysed by a senior radiologist. Data analysis was performed using Statistical Package for the Social Sciences (SPSS) version 20.

RESULTS

We studied 184 COVID-19 patients who were suspected to have PTE disease. CTPA examinations revealed a total of 150 patients (81.5%) suffered from concomitant PTE disease. Among the PTE cohort, the commonest comorbidities were diabetes mellitus (n=78, 52.0%), hypertension (n=66, 44.0%) and dyslipidaemia (n=25, 16.7%). They were generally more ill than the non-PTE cohort as they reported a significantly higher COVID-19 disease category during CTPA examination with p=0.042. Expectedly, their length of both intensive care unit stays (median number of days 8 vs. 3; p=0.021) and hospital stays (median number of days 14.5 vs. 12; p=0.006) were significantly longer. Intriguingly, almost all the subjects had received either therapeutic anticoagulation or thromboprophylactic therapy prior to CTPA examination (n=173, 94.0%). Besides, laboratory data analysis identified a significantly higher peak C-reactive protein (median 124.1 vs. 82.1; p=0.027) and ferritin levels (median 1469 vs. 1229; p=0.024) among them. Evaluation of CT features showed that COVID-19 pneumonia pattern (p<0.001) and pulmonary angiopathy (p<0.001) were significantly more profound among the PTE cohort. To note, the most proximal pulmonary thrombosis was located in the segmental (n=3, 2.0%) and subsegmental pulmonary arteries (n=147, 98.0%). Also, the thrombosis predominantly occurred in bilateral lungs with multilobar involvement (n=95, 63.3%).

CONCLUSION

Overall, PTE disease remains prevalent among COVID-19 patients despite timely administration of thromboprophylactic therapy. The presence of hyperinflammatory activities, unique thrombotic locations as well as concurrent pulmonary parenchyma and vasculature aberrations in our PTE cohort implicate immunothrombosis as the principal mechanism of this novel phenomenon. We strongly recommend future researchers to elucidate this important clinical disease among our post- COVID vaccination populations.

Dynamics of the fcc-to-bcc phase transition in single-crystalline PdCu alloy nanoparticles

Two most common crystal structures in metals and metal alloys are body-centered cubic (bcc) and face-centered cubic (fcc) structures. The phase transitions between these structures play an important role in the production of durable and functional metal alloys. Despite their technological significance, the details of such phase transitions are largely unknown because of the challenges associated with probing these processes. Here, we describe the nanoscopic details of an fcc-to-bcc phase transition in PdCu alloy nanoparticles (NPs) using in situ heating transmission electron microscopy. Our observations reveal that the bcc phase always nucleates from the edge of the fcc NP, and then propagates across the NP by forming a distinct few-atoms-wide coherent bcc-fcc interface. Notably, this interface acts as an intermediate precursor phase for the nucleation of a bcc phase. These insights into the fcc-to-bcc phase transition are important for understanding solid - solid phase transitions in general and can help to tailor the functional properties of metals and their alloys.

Tuning Electronic Structure and Composition of FeNi Nanoalloys for Enhanced Oxygen Evolution Electrocatalysis via a General Synthesis Strategy

Developing low-cost and efficient oxygen evolution electrocatalysts is key to decarbonization. A facile, surfactant-free, and gram-level biomass-assisted fast heating and cooling synthesis method is reported for synthesizing a series of carbon-encapsulated dense and uniform FeNi nanoalloys with a single-phase face-centered-cubic solid-solution crystalline structure and an average particle size of sub-5 nm. This method also enables precise control of both size and composition. Electrochemical measurements show that among Fe_x Ni_{(1- x )} nanoalloys, Fe_0.5 Ni_0.5 has the best performance. Density functional theory calculations support the experimental findings and reveal that the optimally positioned d-band center of O-covered Fe_0.5 Ni_0.5 renders a half-filled antibonding state, resulting in moderate binding energies of key reaction intermediates. By increasing the total metal content from 25 to 60 wt%, the 60% Fe_0.5 Ni_0.5 /40% C shows an extraordinarily low overpotential of 219 mV at 10 mA cm^-2 with a small Tafel slope of 23.2 mV dec^-1 for the oxygen evolution reaction, which are much lower than most other FeNi-based electrocatalysts and even the state-of-the-art RuO₂ . It also shows robust durability in an alkaline environment for at least 50 h. The gram-level fast heating and cooling synthesis method is extendable to a wide range of binary, ternary, quaternary nanoalloys, as well as quinary and denary high-entropy-alloy nanoparticles.

Risk factors and outcome of community onset Pseudomonas aeruginosa bacteraemia in two Malaysian district specialist hospitals

INTRODUCTION

Despite the ever-growing number of community onset (CO) Pseudomonas aeruginosa (P. aeruginosa) bacteraemia, there is a dearth of district hospital-based research examining this significant infection, which is associated with high mortality. The objectives of this study were as following: (1) to determine the risk factors of CO P. aeruginosa bacteraemia, (2) to compare the 30-day mortality rate between P. aeruginosa and Escherichia coli bacteraemia and (3) to identify the predictors of 30-day mortality for CO gram negative bacteraemia.

METHODS

This is a retrospective case control study in Hospital Seri Manjung and Hospital Teluk Intan, Perak, Malaysia. P. aeruginosa bacteraemia cases that occurred between 1st January 2015 to 31st December 2019 were included, whilst E. coli bacteraemia cases that occurred within the same period were recruited successively until 1:2 case control ratio was achieved. Subjects below 12-year-old and those with polymicrobial bacteraemia were excluded. Demographic, clinical and treatment data were collected using pre-tested data collection forms by trained investigators.

RESULTS

A total of 61 patients with P. aeruginosa bacteraemia and 122 patients with E. coli bacteraemia were included. Recent admission in the earlier three months, regular haemodialysis, immunosuppressive therapy in the past 30 days, chronic wound/pressure sore at presentation and indwelling urinary catheter at presentation were identified as independent predictors of CO pseudomonal bacteraemia. Whilst older age was identified as a negative predictor of CO Pseudomonal bacteraemia (all p<0.05). The 30-day mortality rate was 34.4% in subjects with P. aeruginosa bacteraemia and 27.0% in those with E. coli bacteraemia (p=0.302). Predictors of 30-day mortality for community onset gram negative bacteraemia were as follow: older age, underlying solid tumours, neutropaenia at presentation, in-patient mechanical ventilation, and inpatient nasogastric tube insertion. Unexpectedly, receipt of inappropriate empirical antibiotics which was switched later (delayed and non-delayed switching) was identified as the negative predictors of mortality (all p<0.05).

CONCLUSION

It is prudent to restrict the usage of empirical anti-pseudomonal antibiotics among individuals at risk as liberal usage of broad-spectrum antibiotics engenders emergence of drug resistant organism, particularly in district setting where community onset pseudomonal bacteraemia remains scarce. Subjects with elevated risk of mortality should receive early escalation of care as per sepsis management guidelines.

Design of SiC-Doped Piezoresistive Pressure Sensor for High-Temperature Applications

Within these studies the piezoresistive effect was analyzed for 6H-SiC and 4H-SiC material doped with various elements: N, B, and Sc. Bulk SiC crystals with a specific concentration of dopants were fabricated by the Physical Vapor Transport (PVT) technique. For such materials, the structures and properties were analyzed using X-ray diffraction, SEM, and Hall measurements. The samples in the form of a beam were also prepared and strained (bent) to measure the resistance change (Gauge Factor). Based on the results obtained for bulk materials, piezoresistive thin films on 6H-SiC and 4H-SiC substrate were fabricated by Chemical Vapor Deposition (CVD). Such materials were shaped by Focus Ion Beam (FIB) into pressure sensors with a specific geometry. The characteristics of the sensors made from different materials under a range of pressures and temperatures were obtained and are presented herewith.

Pseudomonas aeruginosa bacteraemia: A five-year analysis of epidemiology, clinical profiles, and outcome in a Malaysian district hospital

INTRODUCTION

Pseudomonas aeruginosa is known to be the epitome of nosocomial infections associated with high morbidity and mortality. The dearth of local pseudomonal studies has prompted us to conduct this study with the following objectives: (1) to examine the local pseudomonal bacteraemia (PB) epidemiology and clinical characteristics, (2) to compare the 30-day mortality among PB of different onsets and (3) to determine the predictors of 30-day mortality outcome.

METHODS

This retrospective study was conducted in Hospital Seri Manjung, Perak, Malaysia. All cases of blood culture proven PB that occurred between 1st January 2015 and 31st December 2019 were reviewed. Subjects below 12 year old and whose index blood cultures grew more than one organism were excluded. Demographic, clinical and treatment data were collected using pre-tested data collection forms and analysed using SPSS version 20.0.

RESULTS

Among the 59 subjects included, healthcare associated (HCA) infections were the most prevalent, next to hospital onset (HO) and community onset (CO) infections. The commonest underlying comorbidities were cardiovascular disease, diabetes mellitus, and chronic kidney disease. Respiratory tract was the most frequently implicated source amongst all, while the urinary tract was more frequently implicated as the source of infection among HCA cases. Seventeen patients were admitted to ICU, and they were predominantly from the HO group. Despite having a higher rate of adequate empirical antibiotics administered, the HO group reported the lowest 30-day survival rate. Multiple logistic regression analysis demonstrated the following were independent predictors of 30-day mortality: requiring mechanical ventilator support, requiring central venous line insertion, not requiring surgery, and receiving inappropriate definite antibiotics.

CONCLUSION

The incidence of community onset PB was appreciably low, as cases were predominantly HCA and HO in origin. Significant morbidities were observed among pseudomonal infections, with HO infections portending the worst prognosis. Lastly, prognostic factors for determining the mortality caused by PB depended more on the severity of sepsis than the timeliness of appropriate antibiotics.

Tuning oxygen reduction activity on chromia surface via alloying: a DFT study

Economical electro-catalysts for the oxygen reduction reaction (ORR) are highly desirable for a range of advance energy storage technologies. Chromium compounds have been suggested as one possible source of non-precious metal based catalysts for oxygen reduction reaction (ORR), especially chromia (Cr₂ O₃ ) which is the most stable form of Cr oxide at room temperature. Using density functional theory+U calculations, we investigate the 4-electron ORR on the hydroxylated Cr₂ O₃ surfaces alloyed with 17 different transition metals. On the one hand, we find that the ORR overpotential is lower when the Cr₂ O₃ surface alloyed with elements towards the end of both the first and second rows of transition metals. Among these elements, Cd alloyed Cr₂ O₃ surface is found to promote the ORR the most, but due to its high toxicity and price it loses out to Zn as the recommended alloyant. On the other hand, we find that the ORR overpotential is generally higher and less varied on the Cr₂ O₃ surface alloyed with the early-to-mid row transition metal elements (e. g. Zr, Ti). As Cr₂ O₃ is also a major component in the passive film on stainless steels, where a low ORR rate is desirable to reduce the impact of localized corrosion. This implies that alloying with early-to-mid row transition elements could be beneficial to stainless steels. The difference in oxygen reduction activity is attributed to the tendency of forming stable ORR intermediates during the oxygen reduction process.

Pericardial abscess: The corollary of disseminated Methicillin-resistant Staphylococcus aureus following diabetic foot ulcer infection

Methicillin-resistant Staphylococcus aureus (MRSA) purulent pericarditis, characterised by frank pus collection or microscopic pyogenic effusion in the pericardium represents the most serious form of pericardial infection. The route of MRSA acquisition in pericardial abscess commonly occurs via the blood stream infection and it is more commonly observed among immunocompromised individuals. To date, diabetic foot ulcer infection rarely disseminates and becomes a nidus for pericardial infection. Herein, we report an unusual case of MRSA pericardial abscess in a 44-year-old man who presented at Hospital Seri Manjung, Malaysia with cardiac tamponade. Past medical history indicated that he was recently treated for infected diabetic foot ulcer with MRSA bacteraemia one week earlier. Despite adequate pericardial drainage and extended parenteral vancomycin therapy, this case ended in fatality on day 42 of admission due to nosocomial infection. It is hoped that this report serves to increase the vigilance among clinicians that diabetic foot ulcer infections have the potential to progress to pericardial abscess in the presence of MRSA bacteraemia, although they may appear seemingly innocuous at presentation. Systemic vancomycin must be instituted promptly when MRSA bacteraemia is confirmed in order to circumvent the propagation of MRSA.

Silent microaspirations: The forerunner to the diagnosis of bulbar onset myasthenia gravis in a young woman

Recurrent pneumonia warrants a diligent work-up to identify the underlying cause that perpetuates the disease process. Insidious bulbar dysfunction is arguably the most devastating as it would be diagnosed late after significant pulmonary complications due to chronic micro-aspiration. Bulbar disorder should be considered as the potential aetiology of recurrent pulmonary infections in the young population after excluding immunodeficiency disorder and respiratory anatomical anomaly. This report illustrates a rare case of bulbar onset myasthenia gravis which manifested as focal bronchiolectasis due to recurrent undiagnosed aspiration pneumonia three years earlier. Absence of hallmark features of Myasthenia Gravis (MG) such as ptosis, opthalmoplegia and proximal muscle weakness contributed to the diagnostic delay and challenges in this case. The diagnosis was established with the collaboration of multidisciplinary teams. Subsequent correct therapeutic interventions resulted in remarkable recovery in functional status and prevented her from further aspiration in the long run.

Improved Alignment of PEDOT:PSS Induced by in-situ Crystallization of "Green" Dimethylsulfone Molecules to Enhance the Polymer Thermoelectric Performance

Dimethylsulfone (DMSO2), a small organic molecule, was observed to induce the alignment of poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) via in-situ crystallization in PEDOT:PSS mixture, which was verified by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). A chemically stable dopant, DMSO2, remarkably raised the electrical conductivity of the PEDOT:PSS film, which was fabricated from pre-mixed solution of PEDOT:PSS and DMSO2, up to 1080 S/cm, and more importantly, such a PEDOT:PSS film showed a long-term humidity stability and it retained near 90% electric conductivity after 60 days, suggesting DMSO2 is promising for an eco-friendly alternative to replace dimethyl sulfoxide (DMSO), ethylene glycol (EG) and various acids dopants that have been widely employed to dope and post-treat PEDOT:PSS. Pairwise interaction energies and free energy of solvation between PEDOT:PSS and DMSO2 were calculated by first-principles and molecular mechanics, respectively, revealing the mechanism of DMSO2 in enhancing the electrical conductivity.

Intermediate Structures of Pt-Ni Nanoparticles during Selective Chemical and Electrochemical Etching

Both chemical and electrochemical etching are effective methods for tailoring the surface composition of Pt-based catalytic bimetallic nanoparticles (NPs). However, the detailed nanoscale etching mechanisms, which are needed for achieving fine control over the etch processes, are still not understood. Here, we study selective chemical and electrochemical Ni etching of Pt-Ni rhombic dodecahedron NPs using in situ liquid-phase transmission electron microscopy. Our real-time observations show that the intermediate NP structures evolve differently in the two cases. Chemical etching of Ni starts from localized pits on the NP surface, in contrast to the uniform dissolution of Ni during the electrochemical etching. Our study reveals how oxidative etching participates in the removal of a non-noble metal and the subsequent formation of noble-metal-rich NPs. The mechanistic insights reported here highlight the role of a native surface oxide layer on the etching behavior, which is important for the design of NPs with specific surface composition for applications in electrocatalysis.

2019 John Insall Award: Fructosamine is a better glycaemic marker compared with glycated haemoglobin (HbA1C) in predicting adverse outcomes following total knee arthroplasty: a prospective multicentre study

AIMS

The best marker for assessing glycaemic control prior to total knee arthroplasty (TKA) remains unknown. The purpose of this study was to assess the utility of fructosamine compared with glycated haemoglobin (HbA1c) in predicting early complications following TKA, and to determine the threshold above which the risk of complications increased markedly.

PATIENTS AND METHODS

This prospective multi-institutional study evaluated primary TKA patients from four academic institutions. Patients (both diabetics and non-diabetics) were assessed using fructosamine and HbA1c levels within 30 days of surgery. Complications were assessed for 12 weeks from surgery and included prosthetic joint infection (PJI), wound complication, re-admission, re-operation, and death. The Youden's index was used to determine the cut-off for fructosamine and HbA1c associated with complications. Two additional cut-offs for HbA1c were examined: 7% and 7.5% and compared with fructosamine as a predictor for complications.

RESULTS

Overall, 1119 patients (441 men, 678 women) were included in the study. Fructosamine level of 293 µmol/l was identified as the optimal cut-off associated with complications. Patients with high fructosamine (> 293 µmol/l) were 11.2 times more likely to develop PJI compared with patients with low fructosamine (p = 0.001). Re-admission and re-operation rates were 4.2 and 4.5 times higher in patients with fructosamine above the threshold (p = 0.005 and p = 0.019, respectively). One patient (1.7%) from the elevated fructosamine group died compared with one patient (0.1%) in the normal fructosamine group (p = 0.10). These complications remained statistically significant in multiple regression analysis. Unlike fructosamine, all three cut-offs for HbA1c failed to show a significant association with complications.

CONCLUSION

Fructosamine is a valid and an excellent predictor of complications following TKA. It better reflects the glycaemic control, has greater predictive power for adverse events, and responds quicker to treatment compared with HbA1c. These findings support the screening of all patients undergoing TKA using fructosamine and in those with a level above 293 µmol/l, the risk of surgery should be carefully weighed against its benefit. Cite this article: Bone Joint J 2019;101-B(7 Supple C):3-9.

Optimizing special quasirandom structure (SQS) models for accurate functional property prediction in disordered 2D alloys

2D materials such as MXenes have garnered attention in a wide field of applications ranging from energy to environment to medical. Properties of 2D materials can be tailored via alloying and in some cases, solid-solutions (disordered alloys) are formed. To predict the disordered alloy properties via first-principles, the model structure needs to imitate the random arrangements of alloyants and yet remains computationally tractable. Using density functional theory and the cluster expansion method, we investigate the accuracy of using of special quasirandom structures (SQSs) for predicting disordered 2D alloy properties, evaluating the effect of SQS supercell size on the prediction quality of formation energies, elastic properties, and structural parameters. We illustrate the findings with 5 different disordered binary [Formula: see text] MXene alloy systems (where M  =  Ti and M'  =  Zr, Hf, V, Nb, or Ta), demonstrating that SQSs around 6-8 times the primitive cell (N  =  6-8) are sufficient to attain convergence in the property predictions versus supercell size. For formation energies, SQSs with N  >  4 are found to reproduce the formation energies of the fully disordered phase within ~2.5 meV. For the simulation of the experimentally-synthesized TiNbCO₂, we find convergence in structural parameters and elastic tensors at N ~ 6. We traced the convergence of the predictions to the convergence in the band structure-related properties via analysis of the electronic densities-of-states and the projected crystal overlap Hamilton population. Our findings suggest that modest sized SQSs would reproduce the properties of disordered MXene alloys. The results should help guide the investigations of structure-property relationships in other disordered 2D materials as well.

Fatal Leptospirosis and Escherichia coli co-infection in a post-partum woman

The occurrence of Leptospirosis and Escherichia coli coinfection in the post-partum period is a novel case. This report illustrated a previously well woman from a suburban area presented with acute neurological deterioration following a two days history of fever during her puerperal period. Early interventions with fluids, broad spectrum antibiotics and intensive supportive care were given. Despite that, she deteriorated rapidly and developed pulmonary hemorrhage, disseminated intravascular coagulopathy, and multi-organ failure. She succumbed within 12 hours of admission. The knowledge about such fatal co-infections should be disseminated to medical practitioners encountering Leptospirosis infection and general public.

Enhancing the Photocatalytic Performance of MXenes via Stoichiometry Engineering of Their Electronic and Optical Properties

Combining both density functional theory and the cluster expansion method, we investigate 3 binary MXene alloy systems of semiconducting Ti₂CO₂, Zr₂CO₂, and Hf₂CO₂, where the transition metals substitute one another (i.e., Ti_{2(1- x)}Zr_{2 x}CO₂, Ti_{2(1- x)}Hf_{2 x}CO₂, and Zr_{2(1- x)}Hf_{2 x}CO₂). We show that this group of MXene alloys forms the solid-solution phase across all compositions. Special quasirandom structures are generated to model the solid-solution phase of these alloys, using which we demonstrate how their structural, mechanical, electronic, and optical properties are tuned via stoichiometry engineering. These alloys exhibit outstanding mechanical strength and stability. They possess indirect band gaps of 1.25-1.80 eV. For Ti_{2(1- x)}Zr_{2 x}CO₂ and Ti_{2(1- x)}Hf_{2 x}CO₂, they display higher absorbance in the solar spectrum than their constituent Zr₂CO₂ and Hf₂CO₂, respectively. Most of the MXene alloys also show appropriately aligned band edges for water splitting. We predict the Ti_{2(1- x)}Zr_{2 x}CO₂ alloy with x = 0.2778 to be the most promising water-splitting photocatalyst among the MXenes studied here, outperforming its constituents, Ti₂CO₂ and Zr₂CO₂, when solar absorbance performance and band-edge alignments are simultaneously considered. This work demonstrates that alloying can be used to effectively tune photocatalytic performance.

The crucial role of molecular testing to facilitate the diagnosis of pneumocystis pneumonia during pregnancy

Pneumocystis pneumonia is an important human immunodeficiency virus (HIV)-associated opportunistic infection, and especially so in pregnant HIV-positive patients. We report a case of a 40-year-old woman in her first trimester of pregnancy who initially presented with acute gastroenteritis symptoms but due to a history of high-risk behaviour and the observation of oral thrush, she was worked up for HIV infection. Her retroviral status was positive and her CD4+ T cell count was only 8 cells/µL. She was also worked up for pneumocystis pneumonia due to the presence of mild resting tachypnoea and a notable drop in oxygen saturation (from 100% to 88%) following brief ambulation. Her chest radiograph revealed bilaterally symmetrical lower zone reticular opacities and Giemsa staining of her bronchoalveolar lavage (BAL) was negative for Pneumocystis jirovecii cysts. However, real-time P. jirovecii polymerase chain reaction (PCR) testing on the same BAL specimen revealed the presence of the organism. A course of oral co-trimoxazole plus prednisolone was commenced and her clinical condition improved.

Ruthenium-Tungsten Composite Catalyst for the Efficient and Contamination-Resistant Electrochemical Evolution of Hydrogen

A new catalyst, prepared by a simple physical mixing of ruthenium (Ru) and tungsten (W) powders, has been discovered to interact synergistically to enhance the electrochemical hydrogen evolution reaction (HER). In an aqueous 0.5 M H₂SO₄ electrolyte, this catalyst, which contained a miniscule loading of 2-5 nm sized Ru nanoparticles (5.6 μg Ru per cm² of geometric surface area of the working electrode), required an overpotential of only 85 mV to drive 10 mA/cm² of H₂ evolution. Interestingly, our catalyst also exhibited good immunity against deactivation during HER from ionic contaminants, such as Cu²⁺ (over 24 h). We unravel the mechanism of synergy between W and Ru for catalyzing H₂ evolution using Cu underpotential deposition, photoelectron spectroscopy, and density functional theory (DFT) calculations. We found a decrease in the d-band and an increase in the electron work function of Ru in the mixed composite, which made it bind to H more weakly (more Pt-like). The H-adsorption energy on Ru deposited on W was found, by DFT, to be very close to that of Pt(111), explaining the improved HER activity.

Low Li+ Insertion Barrier Carbon for High Energy Efficient Lithium-Ion Capacitor

Lithium-ion capacitor (LIC) is an attractive energy-storage device (ESD) that promises high energy density at moderate power density. However, the key challenge in its design is the low energy efficient negative electrode, which barred the realization of such research system in fulfilling the current ESD technological inadequacy due to its poor overall energy efficiency. Large voltage hysteresis is the main issue behind high energy density alloying/conversion-type materials, which reduces the electrode energy efficiency. Insertion-type material though averted in most research due to the low capacity remains to be highly favorable in commercial application due to its lower voltage hysteresis. To further reduce voltage hysteresis and increase capacity, amorphous carbon with wider interlayer spacing has been demonstrated in the simulation result to significantly reduce Li⁺ insertion barrier. Hence, by employing such amorphous carbon, together with disordered carbon positive electrode, a high energy efficient LIC with round-trip energy efficiency of 84.3% with a maximum energy density of 133 Wh kg^-1 at low power density of 210 W kg^-1 can be achieved.

Reconfiguring crystal and electronic structures of MoS2 by substitutional doping

Doping of traditional semiconductors has enabled technological applications in modern electronics by tailoring their chemical, optical and electronic properties. However, substitutional doping in two-dimensional semiconductors is at a comparatively early stage, and the resultant effects are less explored. In this work, we report unusual effects of degenerate doping with Nb on structural, electronic and optical characteristics of MoS₂ crystals. The doping readily induces a structural transformation from naturally occurring 2H stacking to 3R stacking. Electronically, a strong interaction of the Nb impurity states with the host valence bands drastically and nonlinearly modifies the electronic band structure with the valence band maximum of multilayer MoS₂ at the Γ point pushed upward by hybridization with the Nb states. When thinned down to monolayers, in stark contrast, such significant nonlinear effect vanishes, instead resulting in strong and broadband photoluminescence via the formation of exciton complexes tightly bound to neutral acceptors.

Substitutional doping is well-established in traditional semiconductors but has not been extensively explored in two-dimensional semiconductors. Here, the authors investigate the structural and electronic effects of Nb doping in MoS₂ crystals.

High-Throughput Survey of Ordering Configurations in MXene Alloys Across Compositions and Temperatures

2D transition metal carbides and nitrides known as MXenes are gaining increasing attention. About 20 of them have been synthesized (more predicted) and their applications in fields ranging from energy storage and electromagnetic shielding to medicine are being explored. To facilitate the search for double-transition-metal MXenes, we explore the structure-stability relationship for 8 MXene alloy systems, namely, (V_1-xMo_x)₃C₂, (Nb_1-xMo_x)₃C₂, (Ta_1-xMo_x)₃C₂, (Ti_1-xMo_x)₃C₂, (Ti_1-xNb_x)₃C₂, (Ti_1-xTa_x)₃C₂, (Ti_1-xV_x)₃C₂, and (Nb_1-xV_x)₃C_2, with 0 ≤ x ≤ 1, using high-throughput computations. Starting from density-functional theory calculated formation energies, we used the cluster expansion method to build quick-to-compute interactions, enabling us to scan through the formation energies of millions of alloying configurations. For the Mo-rich MXenes, (M1_1-xMo_x)₃C₂ (where M1: Ti, V, Nb, Ta) Mo atoms prefer to occupy the surface layers, and ordering persists to high temperatures, based on our Monte Carlo simulations. When Ti is alloyed with Nb or Ta, in the Ti-rich MXenes, Ti atoms prefer the surface layers (e.g., Ti-C-Nb-C-Ti sequence), and in the Nb- or Ta-rich MXenes, Ti occupies only one surface layer and the other two layers are Nb or Ta (e.g., Ti-C-Nb-C-Nb), exhibiting asymmetric ordering. However, alloying Ti with V results in solid solutions across all compositions. (Nb_1-xV_x)₃C₂ phase separates at lower temperatures but forms solid solutions at synthesis temperatures. Postsynthesis annealing at moderate temperatures (800 to 1000 K) increases the ordering for all the compositions. Lastly, by investigating the stability of their precursor MAX phases and surface-terminated MXenes, we discuss the synthesis possibilities of highly ordered MXenes.

A case series of dermatological emergencies - Erythroderma

Erythroderma can be life-threatening, primarily because of its metabolic burden and complications. It is mandatory to establish its etiopathology in order to facilitate precise and definitive management. This disorder may be the morphologic presentation of a variety of cutaneous and systemic diseases. Detailed history and thorough work-up is therefore essential. Management of erythroderma involves multi-disciplines with progress monitoring especially on signs and symptoms suggestive of acute skin failure induced complications. Early diagnosis and referral of erythroderma to centres with dermatological services is crucial and will directly affect the outcome of the patients.

Health promotion board-ministry of health clinical practice guidelines: treating tobacco use and dependence

The Health Promotion Board (HPB) has updated the clinical practice guidelines on Treating Tobacco Use and Dependence to provide health professionals in Singapore with evidence-based interventions for smoking cessation. This article reproduces the introduction and executive summary of key guideline recommendations (with recommendations from the guidelines) from the HPB-MOH Clinical Practice Guidelines on Treating Tobacco Use and Dependence, for the information of SMJ readers. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Health Promotion Board website: http://www.hpb.gov.sg/cpg-smoking-cessation. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Impact of consultant-led care in early pregnancy unit

Early pregnancy complication remains a significant cause of maternal morbidity and mortality. Despite the paucity of evidence to support consultant-led early pregnancy unit over nurse- or sonographer-led services, hospitals have devoted scarce resources to appoint consultants to lead their early pregnancy units. We compared the management and outcomes of confirmed and suspected ectopic pregnancy 1 year before and one year after the transition from a nurse-led to a consultant-led early pregnancy unit in a London hospital. Our study showed improvements in the rates of negative laparoscopy, ruptured ectopic pregnancy during follow-up, need for laparotomy, ITU admission and length of stay and statistically significant reduction in operative intervention, without concomitant rise in morbidity or mortality in women with confirmed or suspected ectopic pregnancies.

Nutritional assessment in an Asian nursing home and its association with mortality

OBJECTIVE

To study the nutritional status of nursing home residents in a multi-racial Asian society and its role in predicting short-term mortality independent of functional status and comorbidities.

DESIGN

Cross-sectional study with prospective collection of mortality data.

SETTING

Nursing home facility in Singapore.

SUBJECTS

A total of 154 patients (mean age 77 +/- 12 years, 53.2% women).

METHODS

We evaluated the demographic details, Mini Nutritional Assessment (MNA) scores, body mass index (BMI) and anthropometric measurements of the participants. Functional status and comorbidities were characterized by the modified Barthel Index and Charlson's comorbidity index respectively.

RESULTS

Prevalence of undernutrition were 52% (n= 80) and 39% (n=60) when determined by BMI < 18.5 kg/m2 and MNA <17 respectively. Mortality was 25.3% (n= 39) over 2 years. Baseline factors associated with mortality include increased age, low Barthel's score, BMI < 18.5 kg/m2 and MNA < 17 (OR= 1.05, 1.01, 3.08 and 3.03 respectively, all p < 0.05). The association between low BMI and mortality remained significant (p=0.027) after adjustment for patient's age, gender, Barthel's and Charlson's scores, and prior nutritional intervention, but the association between MNA and mortality was diminished (p=0.106).

CONCLUSION

There was a high prevalence of undernutrition in this nursing home population, and the diagnosis is an important predictor of mortality. Formal nutritional screening and targeted interventions may improve important clinical outcomes.

Birthweights in sickle cell trait pregnancies

OBJECTIVES

Available evidence on the effect of sickle cell trait (SCT) on birthweight is conflicting, not gestational age specific, and does not account for maternal and infant factors. The objectives of this study are to determine the contemporary mean birthweight, mean customised birthweight centile, and to analyse the risk of small-for-gestational-age (SGA) and large-for-gestational-age (LGA) babies in SCT pregnancies.

DESIGN

Large retrospective cohort study.

SETTING

London hospital.

POPULATION

Singleton pregnancies between 24 and 42 completed weeks delivered between 2000 and 2005 in parturient with body mass index between 18.0 and 35.0 kg/m(2).

METHODS

All qualifying pregnancies were identified on Terra Nova Healthware. Birthweight centiles of these cases were computed with Gardosi customised bulk centile calculator using collected data on maternal height, weight, ethnicity and parity, and the infant's gender, gestational age and birthweight. Birthweight and birthweight centiles of SCT and pregnancies with no haemoglobinopathy (control) were compared. Statistical analysis was performed using Stata version 9.2.

MAIN OUTCOME MEASURES

Birthweight and birthweight centiles.

RESULTS

Five hundred and five SCT and 16 320 controls were analysed. The mean birthweight of SCT pregnancies was 3223 g, 57 g lower than controls (P = 0.024). However, its mean birthweight centile was 49.0% similar to that of controls' 47.5% (P = 0.320). There is an apparent risk of LGA babies in SCT pregnancies, but logistic regression analysis suggests that the odds are related to being an older non-white parturient and a male infant rather than SCT status.

CONCLUSIONS

SCT is not a risk factor for SGA or LGA infants.

High performance thyratron driver with low jitter

We report the design and development of insulated gate bipolar junction transistor based high performance driver for operating thyratrons in grounded grid mode. With careful design, the driver meets the specification of trigger output pulse rise time less than 30 ns, jitter less than +/-1 ns, and time delay less than 160 ns. It produces a -600 V pulse of 500 ns duration (full width at half maximum) at repetition rate ranging from 1 Hz to 1.14 kHz. The developed module also facilitates heating and biasing units along with protection circuitry in one complete package.

Study of a chemically amplified resist for X-ray lithography by Fourier transform infrared spectroscopy

Future applications of microelectromechanical systems (MEMS) require lithographic performance of very high aspect ratio. Chemically amplified resists (CARs) such as the negative tone commercial SU-8 provide critical advantages in sensitivity, resolution, and process efficiency in deep ultraviolet, electron-beam, and X-ray lithographies (XRLs), which result in a very high aspect ratio. In this investigation, an SU-8 resist was characterized and optimized for X-ray lithographic applications by studying the cross-linking process of the resist under different conditions of resist thickness and X-ray exposure dose. The exposure dose of soft X-ray (SXR) irradiation at the average weighted wavelength of 1.20 nm from a plasma focus device ranges from 100 to 1600 mJ/cm(2) on the resist surface. Resist thickness varies from 3.5 to 15 mum. The cross-linking process of the resist during post-exposure bake (PEB) was accurately monitored using Fourier transform infrared (FT-IR) spectroscopy. The infrared absorption peaks at 862, 914, 972, and 1128 cm(-1) in the spectrum of the SU-8 resist were found to be useful indicators for the completion of cross-linking in the resist. Results of the experiments showed that the cross-linking of SU-8 was optimized at the exposure dose of 800 mJ/cm(2) for resist thicknesses of 3.5, 9.5, and 15 microm. PEB temperature was set at 95 degrees C and time at 3 min. The resist thickness was measured using interference patterns in the FT-IR spectra of the resist. Test structures with an aspect ratio 3:1 on 10 microm thick SU-8 resist film were obtained using scanning electron microscopy (SEM).

Impact of a pharmacist consult clinic on a hospital-based geriatric outpatient clinic in Singapore

INTRODUCTION

We study the impact of a pharmacist consult clinic on the care of elderly outpatients based on the Health Belief Model that the perceived benefits (improvement in medication knowledge, clinical status and perception) and attached barriers (cost and number of medication and adverse drug reactions) can influence health behaviour (medication compliance).

MATERIALS AND METHODS

A randomised controlled study of 136 eligible patients with risk factors for non-compliance, using Zelen's design, was conducted in a hospital-based geriatric outpatient clinic from November 2001 to June 2002. All patients were assessed for outcome variables at baseline and 2 months later.

RESULTS

One hundred and twenty-six patients were included in the intention-to-treat analysis. There were 104 pharmacist interventions with a physician acceptance rate of 76%. There was a significant improvement in medication knowledge with regards to indication (P = 0.03) and the composite dose, frequency and indication score (P = 0.06), as well as a decrease in residual adverse drug reactions that persisted at month 2 and cost avoidance of dollars 387.28 over 2 months. There was no significant difference in perception, clinical status or decrease in number of medications. The intervention group showed an improvement in adjusted compliance (odds ration [OR] = 2.52; 90% confidence interval [CI], 1.09 to 5.83) based on the ordered logistic regression model. Perception of severity of illness at baseline (OR = 1.30; 90% CI, 1.04 to 1.62), number of medication remembering methods (OR = 1.87; 90% CI, 1.08 to 3.25) and the use of routine habits (OR = 4.48; 90% CI, 1.51 to 13.28) and medication aids (OR = 3.68; 90% CI, 1.04 to 13.06) significantly affected compliance.

CONCLUSION

The addition of a pharmacist consult clinic to the management of selected geriatric outpatients can improve compliance, with the attendant benefits of improving medication knowledge, cost avoidance and reducing residual adverse drug reactions.

Urinary incontinence in older persons: a simple approach to a complex problem

Urinary incontinence is a major geriatric syndrome with significant morbidity and even mortality. However, it is under-recognised and inadequately managed despite its impact and cost. Continence in the older person is maintained by the fine balance between the integrity of the lower urinary tract, the cognitive ability and motivation to keep dry, and adequate mobility and dexterity to void; impairment of any of the three can result in incontinence. The management of older persons with urinary incontinence involves, i) identifying and reversing transient incontinence, ii) excluding urinary retention, iii) deciding on the need of special tests (imaging, screening for malignancy, magnetic resonance imaging [MRI] for spinal cord, urodynamic assessment) to exclude sinister causes, and iv) deciding on the need to refer the specialist. With careful evaluation, continence in the older persons can be restored in most cases.

FT-IR study of a chemically amplified resist for X-ray lithography

Microelectronic devices for future applications demand lithographic performance that falls within the 0.10 microm region and below. Chemically amplified resists (CARs), such as the positive tone commercial UVIII resist, offer a substantial gain in sensitivity, resolution, and process efficiency in deep ultraviolet, e-beam, and X-ray lithographies. In this work, the UVIII resist is characterized for X-ray lithographic applications by studying the "deprotection" or acid generation-diffusion process of the resist under different conditions of post-exposure bake (PEB) temperature and time, and of X-ray exposure dose. The X-ray irradiation from a copper anode at a wavelength of 1.33 nm was at an intensity of 30 microW/cm2 on the resist surface. The deprotection process of the resist during PEB was accurately monitored by using Fourier transform infrared (FT-IR) spectroscopy. The infrared absorption peaks at 1151, 1369, and 2977 cm(-1) in the spectrum of the UVIII resist were found to be useful indicators for the completion of deprotection. Results of the experiments showed that the performance of UVIII could be optimized at the PEB temperature of 140 degrees C, a time of 2 min, and X-ray exposure dose of 12 mJ/cm2. The change in resist thickness after PEB was also measured. The results were confirmed by scanning electron microscopy (SEM) in which a test structure as small as 0.12 microm was obtained in a 1-microm-thick UVIII resist layer.

Urinary retention in hospitalised older women

INTRODUCTION

Information about urinary retention in women is scarce. We conducted a case-control study to identify the symptoms and risk factors associated with urinary retention in hospitalised older women.

MATERIALS AND METHODS

Targeted history (especially lower urinary tract symptoms) and physical examination of 60 women (65 years or older) who had post-void residual urine volume (PRUV) (determined using a portable ultrasound Bladder Scan BVI-2500) of more than 100 mL were studied and compared with 60 controls.

RESULTS

Symptoms of voiding difficulties had low positive predictive value (PPV) and negative predictive value (NPV), except for poor stream, which has a PPV of 100%. Only one-third of the patients with high PRUV had a palpable bladder. Associated with high PRUV were: 1) constipation [odds ratio (OR), 4.12; 95% confidence interval (CI), 1.90-8.91; P = 0.0004]; 2) urinary tract infection (UTI) (OR, 3.36; 95% CI, 1.58-7.12; P = 0.002); 3) impaired mobility (OR, 2.37; 95% CI, 1.12-4.97; P = 0.02); 4) past history of UTI (OR, 3.5; 95% CI, 1.34-9.14; P = 0.014); 5) past history of urinary retention (OR, 6.33; 95% CI, 1.72-23.33; P = 0.004); 6) stroke (OR, 2.5; 95% CI, 1.24-5.41; P = 0.017); 7) diabetes mellitus with microvascular complications (OR, 2.76; 95% CI, 1.08-7.04; P = 0.042). Applying logistic regression analysis, the three best predictive variables for high PRUV were constipation, UTI and past history of urinary retention.

CONCLUSION

Symptoms (except for positive history of poor stream) and signs were unreliable in diagnosing urinary retention in hospitalised older women. Patients with the above risk factors should have their PRUV ascertained, which can be done reliably non-invasively. Early detection with appropriate intervention can potentially prevent the morbidity and mortality associated with urinary retention.

Characterization of facultative oligotrophic bacteria from polar seas by analysis of their fatty acids and 16S rDNA sequences

One hundred and seventy three bacterial strains, isolated previously after enrichment under oligotrophic, psychrophylic conditions from Arctic (98 strains) and Antarctic seawater (75 strains), were characterized by gas-liquid chromatographic analysis of their fatty acid compositions. By numerical analysis, 8 clusters, containing 2 to 59 strains, could be delineated, and 8 strains formed separate branches. Five clusters contained strains from both poles, two minor clusters were confined to Arctic isolates, and one cluster consisted of Antarctic isolates only. The 16S rRNA genes from 23 strains, representing the different fatty acid profile clusters and including the unclustered strains, were sequenced. The sequences grouped with the alpha and gamma Proteobacteria, the high percent G+C gram positives, and the Cytophaga-Flavobacterium-Bacteroides branch. The sequences of strains from 4 clusters and of 7 unclustered strains were closely related (sequence similarities above 97%) to reference sequences of Sulfitobacter mediterraneus, Halomonas variabilis, Alteromonas macleodii, Pseudoalteromonas species, Shewanella frigidimarina, and Rhodococcus fascians. Strains from the other four clusters and an unclustered strain showed sequence similarities below 97% with nearest named neighbours, including Rhizobium, Glaciecola, Pseudomonas, Alteromonas macleodii and Cytophaga marinoflava, indicating that the clusters which they represent form as yet unnamed taxa.

Impaired mobility in older persons attending a geriatric assessment clinic: causes and management

OBJECTIVES

To study the profile of older persons with impaired mobility.

METHODS

A retrospective observational study that reviewed the case records of patients with impaired mobility at a geriatric assessment clinic. Data on mobility status, duration of decline in mobility, functional status, causes, intervention and short-term outcome (up to 16 weeks) were extracted and analysed.

RESULTS

The study included 78 patients (42 males) with the median age of 78 years (61 to 96). About 80% had independent premorbid mobility. At presentation, this declined to 45%. Delayed consultations (more than 2 years) were found in 17% of patients. One third had associated decline in transfer, dressing, toileting or bathing, while 19% also had decline in feeding. In each patient, cause(s), many which were potentially reversible, were identified to have contributed to the immobility. More than one cause was identified in half of the patients. Interventions were prescribed in 88% of these patients. Short-term follow-up (median 7 weeks) showed that 21 had an improvement, 35 had the same and 8 had decline in mobility. There was a significant trend towards better outcome when patient presented early during their course of decline in mobility (p=0.005, linear by linear association = 0.013).

CONCLUSION

Impaired mobility is a common pathway for many diseases, and is associated with significant functional decline. With proper evaluation, the offending causes can be identified. Early consultation is important for the application of appropriate intervention and can result in better outcome.

High-Resolution FTIR Spectrum of the nu(12) Band of trans-d(2)-Ethylene

The nu(12) band of trans-d(2)-ethylene (trans-C(2)H(2)D(2)) has been recorded with an unapodized resolution of 0.0024 cm(-1) in the frequency range of 1240-1360 cm(-1) by Fourier transform infrared (FTIR) spectroscopy. This band was found to be relatively free from any local frequency perturbations. By fitting a total of 1185 infrared transitions of nu(12) with a standard deviation of 0.00043 cm(-1) using a Watson's A-reduced Hamiltonian in the I(r) representation, a set of accurate rovibrational constants for v(12) = 1 state was derived. The nu(12) band is A type with a band center at 1298.03797 +/- 0.00004 cm(-1). Copyright 2000 Academic Press.

High-Resolution Fourier Transform Infrared Spectrum of the nu(12) Fundamental Band of Ethylene (C(2)H(4))

The infrared spectrum of the nu(12) fundamental band of ethylene (C(2)H(4)) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequency range of 1380-1500 cm(-1) using the Fourier transform technique. By assigning and fitting a total of 1387 infrared transitions using a Watson's A-reduced Hamiltonian in the I(r) representation, rovibrational constants for the upper state (v(12) = 1) up to five quartic and three sextic centrifugal distortions terms were derived. They represent the most accurate constants for the band so far. The rms deviation of the fit was 0.00033 cm(-1). The A-type nu(12) band with a band center at 1442.44299 +/- 0.00003 cm(-1) was found to be relatively free from local frequency perturbations. The inertial defect Delta(12) was found to be 0.24201 +/- 0.00002 u Å(2). Copyright 2000 Academic Press.

High-Resolution FTIR Spectrum of the nu(9) Band of Ethylene-D(4) (C(2)D(4))

The spectrum of the nu(9) fundamental band of ethylene-d(4) (C(2)D(4)) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequency range of 2300-2400 cm(-1) using a Fourier transform infrared spectrometer. A total of 549 transitions have been assigned and fitted using a Watson's A-reduced Hamiltonian in the I(r) representation to derive rovibrational constants for the upper state (v(9) = 1) up to five quartic terms with a standard deviation of 0.00087 cm(-1). They represent the most accurate rovibrational constants for the nu(9) band so far. About 30 transitions of K(a)(') = 0, one transition of nu(9) which were identified to be perturbed possibly by the nearby nu(11) and nu(2) + nu(12) transitions, were not included in the final fit. The nu(9) band of C(2)D(4) was found to be basically B-type with an unperturbed band center at 2341.836 94 +/- 0.000 13 cm(-1). Copyright 2000 Academic Press.

Analysis of the Coriolis Interaction between nu(6) and nu(8) Bands of HCOOH

The Fourier transform infrared (FTIR) spectrum of the nu(6) band of formic acid (HCOOH) has been recorded with a resolution of 0.0024 cm(-1) in the spectral range 1050-1160 cm(-1). The nu(6) band was found to be strongly perturbed by the nearby nu(8) band centered at about 1033.5 cm(-1). Using a Watson's A-reduced Hamiltonian in the I(r) representation, and with the inclusion of a-type Coriolis coupling constant, a simultaneous fit of nu(6) and nu(8) was performed. A total of 2485 infrared transitions including about 700 perturbed transitions of nu(6) and 19 transitions of nu(8) was fitted with an rms uncertainty of 0.0006 cm(-1). Accurate rovibrational constants up to sextic order for both nu(6) and nu(8) were obtained. The nu(6) band was analyzed to be a type AB hybrid with a band center at 1104.852109 +/- 0.000050 cm(-1). The band center for nu(8) was found to be 1033.4647 +/- 0.0021 cm(-1). Copyright 2000 Academic Press.