19672 research outputs found
Sort by
Synergistic interaction of metal–acid sites for phenol hydrodeoxygenation over bifunctional Ag/TiO2 nanocatalyst
No full textThe use of silver metal for hydrodeoxygenation (HDO) applications is scarce and different studies have indicated of its varying HDO activity. Several computational studies have reported of silver having almost zero turnover frequency for HDO owing to its high C–O bond breaking energy barrier and low carbon and oxygen binding energies. Herein this work, titania supported silver catalysts were synthesized and firstly used to examine its phenol HDO activity via experimental reaction runs. BET, XRD, FESEM, TEM, EDX, ICP–OES, Pyridine-FTIR, NH 3 -TPD and H 2 -TPD analyses were done to investigate its physicochemical properties. Phenomena of hydrogen spillover and metal–acid site synergy were examined in this study. With the aid of TiO 2 reducible support, hydrogen spillover and metal–acid site interactions were observed to a certain extent but were not as superior as other Pt, Pd, Ni-based catalysts used in other HDO studies. The experimental findings showed that Ag/TiO 2 catalyst has mediocre phenol conversion but high benzene selectivity which confirms the explanation from other computational studies. © 2018 Elsevier B.V
Temperature‐programmed reduction of silver(I) oxide using a titania‐supported silver catalyst under a H 2 atmosphere
No full textReduction kinetics of silver(I) oxide using a titania-supported silver catalyst was analyzed using temperature-programmed reduction (TPR) with hydrogen as a reducing gas. Ag2O reduction to Ag was observed in all samples as a single reduction step occurring at two reduction peaks. Observation of these reduction peaks indicates the existence of different lattice oxygen species, that is, surface and bulk, which are, respectively, attributed to surficial and pore-deposited Ag2O aggregates. The powdered samples exhibited high reducibility with average final oxidation states ranging from 0 to +0.18. The apparent activation energies for Ag2O reduction to Ag metal were 73.35 and 81.71 kJ/mol for surficial and pore-deposited Ag2O aggregates, respectively. In this study, a unimolecular decay model was reported to accurately describe the reduction mechanism of Ag/TiO2 catalysts. Hence, this would also infer that the catalyst reduction is rate-limited by the nucleation of Ag metal instead of the topochemical reaction and the diffusion of hydrogen and oxygen molecules. © 2019 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei
Does duration of rest interval affect 1-Rm bench press test?
No full textBench press 1-RM test is a common assessment to measure maximal strength of the upper body musculatures. Most protocols recommend a rest period between the maximum contraction trials to avoid fatigue which may confound the assessment. Factors that influence fatigue are strength level and fatigue recovery rate especially among sedentary population. The objective of this study was to determine the optimal resting period required among sedentary population when assessing upper body strength using the common 1-RM test, and whether gender influenced the findings. In a randomised, cross-over design, thirty (15 males and 15 females) sedentary participants, aged 18 to 24 years underwent 1-RM bench press tests using machine weight and free weight with different rest period between the 1-RM trials (1-min, 3-min, 5-min). The participants lifted a significantly (p < 0.05) heavier weight when given 3-min rest for both machine weight test (47.16 ± 26.86 kg) and free weight test (40.73 ± 22.03 kg), as well as when given 5-min rest for both machine weight test (48.11 ± 26.91 kg) and free weight test (42.00 ± 24.67 kg), compared to the 1-min rest group for both machine weight test (41.30 ± 24.31 kg) and free weight test (37.11 ± 22.06 kg), for both gender. There was no significant difference between 3-min and 5-min rest periods for both types of weights. There was also no significant difference between the rest periods needed for both gender in both types of weights. Three-min rest interval is enough for sedentary people irrespective of gender for 1-RM strength assessment on either machine weight bench press or free weight. © Universiti Putra Malaysia Pres
Can dynamic consent facilitate the protection of biomedical big data in biobanking in Malaysia?
No full textAs with many other countries, Malaysia is also developing and promoting biomedical research to increase the understanding of human diseases and possible interventions. To facilitate this development, there is a significant growth of biobanks in the country to ensure continuous collection of biological samples for future research, which contain extremely important personal information and health data of the participants involved. Given the vast amount of samples and data accumulated by biobanks, they can be considered as reservoirs of precious biomedical big data. It is therefore imperative for biobanks to have in place regulatory measures to ensure ethical use of the biomedical big data. Malaysia has yet to introduce specific legislation for the field of biobanking. However, it can be argued that its existing Personal Data Protection Act 2010 (PDPA) has laid down legal principles that can be enforced to protect biomedical big data generated by the biobanks. Consent is a mechanism to enable data subjects to exercise their autonomy by determining how their data can be used and ensure compliance with legal principles. However, there are two main concerns surrounding the current practice of consent in biomedical big data in Malaysia. First, it is uncertain that the current practice would be able to respect the underlying notion of autonomy, and second, it is not in accordance with the legal principles of the PDPA. Scholars have deliberated on different strategies of informed consent, and a more interactive approach has recently been introduced: dynamic consent. It is argued that a dynamic consent approach would be able to address these concerns. © 2019, National University of Singapore and Springer Nature Singapore Pte Ltd
Failure mode maps of bio-inspired sandwich beams under repeated low-velocity impact
No full textExisting sandwich structures failure maps are confined only to data from the quasi-static bending tests even for describing failure modes due to the impact event. Strengths of the constituent layers, which are not well-described by these maps, can reasonably change especially under the repeated impact load case. Hence, a new series of more realistic failure mode maps have been developed from the experimentally and numerically obtained observations on recently proposed bio-inspired dual-core sandwich beams in the presence of repeated low-velocity impacts of different energy levels. The beams consist of top and bottom carbon fiber reinforced polymer skins sandwiching the rubber and aluminum honeycomb cores. Departing from the modified Gibson model, an actual presentation of skin and core behaviors has been modeled following the trend of strengths variations for the construction of the failure mode maps when subjected to numerous impact numbers and energies. The produced maps offer the flexibility to accommodate the changes in strengths due to deterioration or densification of constituent layers after impact, and hence following more favorably the physical failure description of the sandwich beams. Accompanying these maps, a general set of mathematical expressions have also been produced for practical convenience. It is found that the failures from observations are within the proposed map boundaries with accuracies ranging from 85.7% to 100%. © 2019 Elsevier Lt
A study on the impact of anthropogenic and geogenic factors on groundwater salinization and seawater intrusion in Gaza coastal aquifer, Palestine: An integrated multi-techniques approach
No full textGroundwater salinization and seawater intrusion (SWI) is a widespread issue affecting many arid and semi-arid coastal regions such as the Gaza Strip, Palestine. The aims of this study were to acquire a comprehensive understanding of the role of anthropogenic and geogenic factors on controlling groundwater salinization and to assess the SWI extent and the hydrogeochemical processes involved. To achieve these objectives, an integrated approach of hydrogeological, hydro-geochemical, and statistical techniques combined with geostatistical semi-variogram modeling was applied on a comprehensive dataset using software (Stata/SE 12, ArcGIS 10.4 and Surfer 16 Golden software Inc.). The results indicate that the intensive groundwater exploitation creates a huge cone of depression covering 75% of the study area and reduces the water table to as much as 19 m below mean sea level (BMSL) at 4.3 km from the shoreline, causing SWI. The extension of SWI depends strongly on the lithological characters of the area. It reached to 48.6% with inland encroachment around 3 km in the northern area. Moreover, the spatial distribution and high pumping rates have significantly influenced the spatial pattern of SWI. Hierarchical cluster analysis (HCA) yielded nine distinct hydrogeochemical signature clusters. Factor analysis (FA) approves that the high groundwater salinization was the result of three main factors loadings that account for 83.86% of the total variance These factors are F1 as salinization (mainly SWI), F2 as mixing of sewage invasion and water hardness and F3 as carbonate dissolution. Factors scores clarify the areas which are more impacted by the different hydro-geochemical processes. Ionic deltas and ionic ratios reveal the dominance of reverse ion exchange process. Moreover, the distinct surplus of sulfate along the sea shoreline may indicate the existence of old seawater transgression. This integrated approach should be useful for efficient groundwater management of the Gaza coastal aquifer system as well as for other similar aquifers. © 2019 Elsevier Lt
Outcome of expandable endoprosthesis: A single centre retrospective review
No full textPurpose: Expandable endoprosthesis allows limb salvage in children with an option to leading a better life. However, the revision rate and implant-related complications impose as a limitation in the skeletal immature. This study investigates the functional outcomes and complications related to expandable endoprosthesis in our centre. Materials and Methods: Twenty surviving patients with expandable endoprosthesis from 2006 till 2015 were scored using Musculoskeletal Tumour Society (MSTS) outcomes instrument and reviewed retrospectively for range of motion of respected joints, limb length discrepancy, number of surgeries performed, complications and oncological outcomes. Patients with less than 2 years of follow-up were excluded from this study. Results: Forty-five percentage patients reached skeletal maturity with initial growing endoprosthesis and 25% of patients were revised to adult modular prosthesis. One hundred fifty-seven surgeries were performed over the 9-year period. The average MSTS score was 90.83%. The mortality rate was 10% within 5 years due to advanced disease. Infection and implant failure rate was 15% each. The event-free survival was 50% and overall survival rate was 90%. Conclusion: There is no single best option for reconstruction in skeletally immature. This study demonstrates a favourable functional and survival outcome of paediatric patients with expandable endoprosthesis. The excellent MSTS functional scores reflect that patients were satisfied and adjusted well to activities of daily living following surgery despite the complications. © The Author(s) 2019
Hand-mixed vancomycin versus commercial tobramycin cement revisited: A study on mechanical and antibacterial properties
No full textPurpose: Arthroplasty-related infection has grown worldwide. Revision procedures for infection are associated with longer operating time, superior amounts of blood loss, and substantial economic encumbrance. To overcome cost, many surgeons opt for hand-mixed vancomycin into the bone cement. The objective of this research was to assess the biomechanical strength and antibacterial properties of hand-mixed vancomycin bone cement at different concentrations with commonly used industrial preblended antibiotic bone cement and plain cement. The target was to determine the ideal concentration of antibiotics that can be used in the preparation of hand-mixed vancomycin cement that delivers maximum antibiotics concentration without compromising its biomechanical properties. Materials and Methods: Vancomycin-impregnated polymethyl methacrylate (PMMA) specimen was hand prepared in varying concentrations (1–4 g). The authors tested three-point bending strength to determine ‘maximum bending load’ and stiffness and its antibacterial activity by looking into the zone of inhibition on methicillin-resistant Staphylococcus aureus-impregnated agar plate. These were compared with the industrial preblended Simplex™ P with 1 g tobramycin. Results: This study exhibited that vancomycin-PMMA disk that contained higher concentration of antibiotics had significantly higher antibacterial activity. The control group (plain cement) and industrial PMMA with preblended antibiotic (tobramycin) showed stable mechanical strength, while the hand-mixed antibiotic cement (HMAC) had variable mechanical strength varying on the concentration of antibiotics used. Conclusion: It was effectively concluded that HMAC is advantageous as a cement spacer; however, it is not recommended for primary arthroplasty and second-stage revision arthroplasty. The recommended maximum concentration of vancomycin based on this study is 2 g/pack (40 g) of cement. Industrial preblended antibiotic cement is superior to hand-mixed cement. © The Author(s) 2019
Unlocking the secrets of banded coral snake (Calliophis intestinalis, Malaysia): A venom with proteome novelty, low toxicity and distinct antigenicity
No full textThe Asiatic coral snakes are basal in the phylogeny of coral snakes. Although envenoming by the Asiatic coral snakes is rarely fatal, little is known about their venom properties and variability from the American coral snakes. Integrating reverse-phase high performance liquid chromatography and nano-liquid chromatography-tandem mass spectrometry, we showed that the venom proteome of the Malaysian banded or striped coral snake (Calliophis intestinalis) was composed of mainly phospholipases A2 (PLA2, 43.4%) and three-finger toxins (3FTx, 20.1%). Within 3FTx, the cytotoxins or cardiotoxins (CTX) dominated while the neurotoxins’ content was much lower. Its subproteomic details contrasted with the 3FTx profile of most Micrurus sp., illustrating a unique dichotomy of venom phenotype between the Old and the New World coral snakes. Calliophis intestinalis venom proteome was correlated with measured enzymatic activities, and in vivo it was myotoxic but non-lethal to mice, frogs and geckos at high doses (5–10 μg/g). The venom contains species-specific toxins with distinct sequences and antigenicity, and the antibodies raised against PLA2 and CTX of other elapids showed poor binding toward its venom antigens. The unique venom proteome of C. intestinalis unveiled a repertoire of novel toxins, and the toxicity test supported the need for post-bite monitoring of myotoxic complication. Significance: Malaysian banded or striped coral snake (Calliophis intestinalis) has a cytotoxin (CTX)-predominating venom proteome, a characteristic shared by its congener, the Malayan blue coral snake (Calliophis bivirgata). With little neurotoxins (NTX), it illustrates a CTX/NTX dichotomy of venom phenotype between the Old World and the New World coral snakes. The low toxicity of the venom imply that C. intestinalis bite envenoming can be managed via symptomatic relief of the mild to moderate pain with appropriate analgesia. Systemically, the serum creatine kinase level of patients should be monitored serially for potential complication of myotoxicity. The distinct antigenicity of the venom proteins implies that the empirical use of heterologous antivenom is mostly inappropriate and not recommended
Evaluating the effect of temperature and concentration on the thermal conductivity of ZnO-TiO2/EG hybrid nanofluid using artificial neural network and curve fitting on experimental data
No full textIn this paper, the experimental data on the thermal conductivity of EG based hybrid nanofluid containing zinc oxide and titanium oxide have been used. At the first, three two-variable correlations have been proposed using curve-fitting on experimental data. After that, the best transfer function for training the artificial neural network has been selected. The input variables of neural network were temperature and solid volume fraction, while the output variable was the thermal conductivity enhancement of the nanofluid. Moreover, the correlation outputs, ANN results and experimental data have been compared. The results showed that there is a good agreement between experimental data and neural network results so that the resulting model of the neural network is able to predict the thermal conductivity enhancement of the nanofluid. The findings also indicated that the accuracy of the neural network is much greater than the curve fitting method to predict thermal conductivity enhancement of ZnO-TiO2/EG hybrid nanofluid