Material optimization of carbon/epoxy composite rotor for spacecraft energy storage

An investigation to optimize the carbon/epoxy composite rotor is performed for the spacecraft energy storage application. A high speed multi-layer rotor design is proposed and different composite materials are tested to achieve the most suitable recipe. First, the analytical rotor evaluation is performed to establish a reliable numerical rotor model. Then, finite element analysis (FEA) is employed in order to optimise the multi-layer composite rotor design. Subsequently, the modal analysis is carried out to determine the rotor natural frequencies and mode shapes for a safe operational regime below 50, 000 rpm

Rational Mutagenesis of Cyclodextrin Glucanotransferase at the Calcium Binding Regions for Enhancement of Thermostability

Studies related to the engineering of calcium binding sites of CGTase are limited. The calcium binding regions that are known for thermostability function were subjected to site-directed mutagenesis in this study. The starting gene-protein is a variant of CGTase Bacillus sp. G1, reported earlier and denoted as “parent CGTase” herein. Four CGTase variants (S182G, S182E, N132R and N28R) were constructed. The two variants with a mutation at residue 182, located adjacent to the Ca-I site and the active site cleft, possessed an enhanced thermostability characteristic. The activity half-life of variant S182G at 60 °C was increased to 94 min, while the parent CGTase was only 22 min. This improvement may be attributed to the formation of a shorter α-helix and the alleviation of unfavorable steric strains by glycine at the corresponding region. For the variant S182E, an extra ionic interaction at the A/B domain interface increased the half-life to 31 min, yet it reduced CGTase activity. The introduction of an ionic interaction at the Ca-I site via the mutation N132R disrupted CGTase catalytic activity. Conversely, the variant N28R, which has an additional ionic interaction at the Ca-II site, displayed increased cyclization activity. However, thermostability was not affected

Effects of physiochemical factors on prokaryotic Biodiversity in Malaysian circumneutral hot springs

Malaysia has a great number of hot springs, especially along the flank of the Banjaran Titiwangsa mountain range. Biological studies of the Malaysian hot springs are rare because of the lack of comprehensive information on their microbial communities. In this study, we report a cultivation-independent census to describe microbial communities in six hot springs. The Ulu Slim (US), Sungai Klah (SK), Dusun Tua (DT), Sungai Serai (SS), Semenyih (SE), and Ayer Hangat (AH) hot springs exhibit circumneutral pH with temperatures ranging from 43°C to 90°C. Genomic DNA was extracted from environmental samples and the V3-V4 hypervariable regions of 16S rRNA genes were amplified, sequenced, and analyzed. High-throughput sequencing analysis showed that microbial richness was high in all samples as indicated by the detection of 6,334-26,244 operational taxonomy units. In total, 59, 61, 72, 73, 65, and 52 bacterial phyla were identified in the US, SK, DT, SS, SE, and AH hot springs, respectively. Generally, Firmicutes and Proteobacteria dominated the bacterial communities in all hot springs. Archaeal communities mainly consisted of Crenarchaeota, Euryarchaeota, and Parvarchaeota. In beta diversity analysis, the hot spring microbial memberships were clustered primarily on the basis of temperature and salinity. Canonical correlation analysis to assess the relationship between the microbial communities and physicochemical variables revealed that diversity patterns were best explained by a combination of physicochemical variables, rather than by individual abiotic variables such as temperature and salinity.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Impact of cardiac arrest centers on the survival of patients with nontraumatic out‐of‐hospital cardiac arrest : a systematic review and meta‐analysis

Background The role of cardiac arrest centers (CACs) in out‐of‐hospital cardiac arrest care systems is continuously evolving. Interpretation of existing literature is limited by heterogeneity in CAC characteristics and types of patients transported to CACs. This study assesses the impact of CACs on survival in out‐of‐hospital cardiac arrest according to varying definitions of CAC and prespecified subgroups. Methods and Results Electronic databases were searched from inception to March 9, 2021 for relevant studies. Centers were considered CACs if self‐declared by study authors and capable of relevant interventions. Main outcomes were survival and neurologically favorable survival at hospital discharge or 30 days. Meta‐analyses were performed for adjusted odds ratio (aOR) and crude odds ratios. Thirty‐six studies were analyzed. Survival with favorable neurological outcome significantly improved with treatment at CACs (aOR, 1.85 [95% CI, 1.52–2.26]), even when including high‐volume centers (aOR, 1.50 [95% CI, 1.18–1.91]) or including improved‐care centers (aOR, 2.13 [95% CI, 1.75–2.59]) as CACs. Survival significantly increased with treatment at CACs (aOR, 1.92 [95% CI, 1.59–2.32]), even when including high‐volume centers (aOR, 1.74 [95% CI, 1.38–2.18]) or when including improved‐care centers (aOR, 1.97 [95% CI, 1.71–2.26]) as CACs. The treatment effect was more pronounced among patients with shockable rhythm ( P =0.006) and without prehospital return of spontaneous circulation ( P =0.005). Conclusions were robust to sensitivity analyses, with no publication bias detected. Conclusions Care at CACs was associated with improved survival and neurological outcomes for patients with nontraumatic out‐of‐hospital cardiac arrest regardless of varying CAC definitions. Patients with shockable rhythms and those without prehospital return of spontaneous circulation benefited more from CACs. Evidence for bypassing hospitals or interhospital transfer remains inconclusive

Domain replacement to elucidate the role of B domain in cgtase thermostability and activity

The B domain of CGTase has been generally accepted as a domain involved in thermostability. However, limited work has been performed in which entire B domain is substituted with the thermostable counterpart. Using overlap extension PCR, we replaced the B domain of a variant of CGTase Bacillus sp. G1 by six other B domains from thermostable CGTases. Likely due to distortion in the substrate-binding cleft adjacent to the active site, variants with the domain replacements from Thermoanaerobacter, Thermococcus, Thermococcus kodakarensis, Anaerobranca gottschalkii and Pyrococcus furiosus completely lost their catalytic function. A mutant designated Cgt_ET1 with a domain replacement from a Bacillus stearopthermophilus ET1 CGTase was the only variant that retained activity after domain exchange. Both the parental enzyme and the mutant Cgt_ET1 had an identical optimum temperature at 60 °C. The activity half-life was 22 min for the parental CGTase, whereas a marked increase to 57 min was observed for the mutant. Further mutagenesis on Cgt_ET1 was performed at residue 188 by replacing a Phe residue with Tyr. The mutant Cgt_ET1_F188Y displayed a decreased activity half-life of 28 min. Both mutants exhibited a better cyclodextrin-forming ability and a faster turnover rate (kcat) than the parental CGTase

Mechanism of adipocyte hormone secretion (leptin and resistin)

Adipose, which was regarded as a passive storage of excess energy (fat), have recently been recognized as a highly active endocrine organ secreting several signal molecules called adipokines. These included leptin and resistin which are critically involved in metabolic disorders. The functions and secretion of leptin and resistin are intimately linked. Both were being controlled by diet. Fasting reduced the serum levels of both adipokines while food intake achieved the opposite [1, 2, 3, 4]. Both adipokines inhibited differentiation of adipocytes [5, 6] and thus development of adipose tissue. They also encouraged angiogenesis [7, 8] and regulated immune responses [9, 10]. However, in some cases, they antagonized with each other such as increased insulin sensitivity by leptin [11] whereas resistin decreased it [3, 12, 13]; leptin reduced gluconeogenesis [14] whereas resistin promoted it [4, 15]; leptin enhanced JAK/Stat3 mediated signal transduction while resistin decreased it [16, 17]. Despite numerous studies, the secretion mechanisms and crosstalks between leptin and resistin remained poorly elucidated. Using TIRFM (total internal reflection fluorescence microscopy) and confocal microscopy on living adipocytes differentiated from 3T3-L1 fibroblasts, evidences pointed that both adipokines were compartmentalized into seperate vesicles. These vesicles did not co-localize with rab5 (marker of early endosomes) or Glut-4 (glucose transporter-4) containing vesicles. In addition, it was found that the secretion of leptin and resistin and the trafficking of leptin and resistin vesicles were oppositely regulated by insulin and protein kinase A. And interestingly, these adipokines adversely influence each other on their secretion and vesicle trafficking.Bachelor of Engineering (Chemical and Biomolecular Engineering

Vesicular storage, vesicle trafficking, and secretion of leptin and resistin : the similarities, differences and interplays

Adipose tissue is a highly active endocrine organ secreting a variety of signaling molecules called adipokines. Leptin and resistin are two adipokines critically involved in metabolic homeostasis. Nevertheless, the secretory pathways of these adipokines and their interplays are poorly elucidated. In this work, we have comparatively studied several key aspects of leptin and resistin secretion from 3T3-L1 adipocytes. It was found that leptin and resistin molecules are compartmentalized into different secretory vesicles. The trafficking of leptin and resistin vesicles, and the secretion of leptin and resistin are oppositely regulated by insulin/glycolytic substrates and cAMP/protein kinase A. Interestingly, these two adipokines adversely influence each other on secretion and vesicle trafficking. Finally, we demonstrated that both leptin and resistin secretion are Ca2+ dependent.Accepted versio

Application of statistical experimental design for optimization of novel α-amylase production by anoxybacillus species

Anoxybacillus sp. DT3-1 is a newly isolated bacterium with amylolytic activity. The gene that encodes the α-amylase was recently cloned and expressed in E. coli system. However, the expression level was far too low to be used for further analysis. The main objective of this study is to enhance the recombinant α-amylase (ADTA) expression level extracellularly. In medium comparison, LB/amp medium was found to be the best medium to support the cell growth and extracellular ADTA production. Subsequently, three factors that affect the ADTA expression which are cells absorbance during induction, concentrations of IPTG and yeast extract were screened using 23 full factorial design. Cells absorbance during induction and IPTG concentration were found to be the significant variables that affected the ADTA production. In the consequently Central Composite Rotatable Design (CCRD), the optimized condition for maximum extracellular ADTA production was determined as OD600 nm 1.52, 0.01 mM IPTG and 0.30% (w/v) yeast extract. The extracellular ADTA production was successfully increased from 30 U in the original medium to 82.29 U

Satellite Images for Monitoring Mangrove Cover Changes in a Fast Growing Economic Region in Southern Peninsular Malaysia

Effective monitoring is necessary to conserve mangroves from further loss in Malaysia. In this context, remote sensing is capable of providing information on mangrove status and changes over a large spatial extent and in a continuous manner. In this study we used Landsat satellite images to analyze the changes over a period of 25 years of mangrove areas in Iskandar Malaysia (IM), the fastest growing national special economic region located in southern Johor, Malaysia. We tested the use of two widely used digital classification techniques to classify mangrove areas. The Maximum Likelihood Classification (MLC) technique provided significantly higher user, producer and overall accuracies and less “salt and pepper effects” compared to the Support Vector Machine (SVM) technique. The classified satellite images using the MLC technique showed that IM lost 6740 ha of mangrove areas from 1989 to 2014. Nevertheless, a gain of 710 ha of mangroves was observed in this region, resulting in a net loss of 6030 ha or 33%. The loss of about 241 ha per year of mangroves was associated with a steady increase in urban land use (1225 ha per year) from 1989 until 2014. Action is necessary to protect the existing mangrove cover from further loss. Gazetting of the remaining mangrove sites as protected areas or forest reserves and introducing tourism activities in mangrove areas can ensure the continued survival of mangroves in IM