Docosahexaenoic acid (DHA, C22:6n-3) plays a vital role in the enhancement of human health, particularly for cognitive, neurological, and visual functions. Marine microalgae, such as members of the genus Aurantiochytrium, are rich in DHA and represent a promising source of omega-3 fatty acids. In this study, levels of glucose, yeast extract, sodium glutamate and sea salt were optimized for enhanced lipid and DHA production by a Malaysian isolate of thraustochytrid, Aurantiochytrium sp. SW1, using response surface methodology (RSM). The optimized medium contained 60 g/L glucose, 2 g/L yeast extract, 24 g/L sodium glutamate and 6 g/L sea salt. This combination produced 17.8 g/L biomass containing 53.9% lipid (9.6 g/L) which contained 44.07% DHA (4.23 g/L). The optimized medium was used in a scale-up run, where a 5 L bench-top bioreactor was employed to verify the applicability of the medium at larger scale. This produced 24.46 g/L biomass containing 38.43% lipid (9.4 g/L), of which 47.87% was DHA (4.5 g/L). The total amount of DHA produced was 25% higher than that produced in the original medium prior to optimization. This result suggests that Aurantiochytrium sp. SW1 could be developed for industrial application as a commercial DHA-producing microorganism.
Graphene oxide (GO) was deposited on the surface of a MnO2 air cathode by thermal evaporation at 50°C from a GO colloidal suspension. Fourier transformed infrared spectroscopy and field emission scanning electron microscopy confirmed the presence of GO on the MnO2 air cathode (GO-MnO2). Voltammetry and chrono-amperometry showed increased currents for the oxygen reduction reaction (ORR) in 6 M KOH solution for GO-MnO2 compared to the MnO2 cathode. The GO-MnO2 was used as an air cathode in an alkaline tin-air cell and produced a maximum power density of 13 mW cm(-2), in contrast to MnO2, which produced a maximum power density of 9.2 mW cm(-2). The electrochemical impedance spectroscopy results suggest that the chemical step for the ORR is the rate determining step, as proposed earlier by different researchers. It is suggested that the presence of GO and electrochemically reduced graphene oxide (ERGO) on the MnO2 surface are responsible for the increased rate of this step, whereby GO and ERGO accelerate the process of electron donation to the MnO2 and to adsorbed oxygen atoms.
Emerging of drug resistant influenza A virus (IAV) has been a big challenge for anti-IAV therapy. In this study, we describe a relatively easy and safe cell-based screening system for anti-IAV replication inhibitors using a non-replicative strain of IAV. A nickel (II) complex of polyhydroxybenzaldehyde N4-thiosemicarbazone (NiPT5) was recently found to exhibit anti-inflammatory activity in vivo and in vitro. NiPT5 impedes the signaling cascades that lead to the activation of NF-κB in response to different stimuli, such as LPS and TNFα. Using our cell-based screening system, we report that pretreating cells with NiPT5 protects cells from influenza A virus (IAV) and vesicular stomatitis virus (VSV) infection. Furthermore, NiPT5 inhibits replication of IAV by inhibiting transcription and translation of vRNAs of IAV. Additionally, NiPT5 reduces IAV-induced type I interferon response and cytokines production. Moreover, NiPT5 prevents activation of NF-κB, and IRF3 in response to IAV infection. These results demonstrate that NiPT5 is a potent antiviral agent that inhibits the early phase of IAV replication.
Local heterogeneity in lipid self-assembly is important for executing the cellular membrane functions. In this work, we chemically modified 2-(2'-hydroxyphenyl)benzoxazole (HBO) and attached a C8 alkyl chain in two different locations to probe the microscopic environment of four lipidic phases of dodecyl β-maltoside. The fluorescence change in HBO and the new probes (HBO-1 and HBO-2) shows that in all phases (micellar, hexagonal, cubic and lamellar) three HBO tautomeric species (solvated syn-enol, anionic, and closed syn-keto) are stable. The formation of multi tautomers reflects the heterogeneity of the lipidic phases. The results indicate that HBO and HBO-1 reside in a similar location within the head group region, whereas HBO-2 is slightly pushed away from the sugar-dominated area. The stability of the solvated syn-enol tautomer is due to the formation of a hydrogen bond between the OH group of the HBO moiety and an adjacent oxygen atom of a sugar unit. The detected HBO anions was proposed to be a consequence of this solvation effect where a hydrogen ion abstraction by the sugar units is enhanced. Our results point to a degree of local heterogeneity and ionization ability in the head group region as a consequence of the sugar amphoterism.
Helicobacter pylori, is an invariably commensal resident of the gut microbiome associated with gastric ulcer in adults. In addition, these patients also suffered from a low grade inflammation that activates the immune system and thus increased shunting of energy to host defense mechanisms. To assess whether a H. pylori infection could affect growth in early life, we determined the expression levels of selected metabolic gut hormones in germ free (GF) and specific pathogen-free (SPF) mice with and without the presence of H. pylori. Despite H. pylori-infected (SPFH) mice display alteration in host metabolism (elevated levels of leptin, insulin and peptide YY) compared to non-infected SPF mice, their growth curves remained the same. SPFH mice also displayed increased level of eotaxin-1. Interestingly, GF mice infected with H. pylori (GFH) also displayed increased levels of ghrelin and PYY. However, in contrast to SPFH mice, GFH showed reduced weight gain and malnutrition. These preliminary findings show that exposure to H. pylori alters host metabolism early in life; but the commensal microbiota in SPF mice can attenuate the growth retarding effect from H. pylori observed in GF mice. Further investigations of possible additional side effects of H. pylori are highly warranted.
Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane. A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique. Remarkably, and in spite of the fact that the proposed approach does not require any mechanical probe, such as tips or apertures, we are able to demonstrate the imaging of a terahertz source with deeply sub-wavelength features (<30 μm) directly in its emission plane.
It is an urgent need to develop new drugs for Mycobacterium tuberculosis (Mtb), and the enzyme, dihydrofolate reductase (DHFR) is a recognised drug target. The crystal structures of methotrexate binding to mt- and h-DHFR separately indicate that the glycerol (GOL) binding site is likely to be critical for the function of mt-DHFR selective inhibitors. We have used in silico methods to screen NCI small molecule database and a group of related compounds were obtained that inhibit mt-DHFR activity and showed bactericidal effects against a test Mtb strain. The binding poses were then analysed and the influence of GOL binding site was studied by using molecular modelling. By comparing the chemical structures, 4 compounds that might be able to occupy the GOL binding site were identified. However, these compounds contain large hydrophobic side chains. As the GOL binding site is more hydrophilic, molecular modelling indicated that these compounds were failed to occupy the GOL site. The most potent inhibitor (compound 6) demonstrated limited selectivity for mt-DHFR, but did contain a novel central core (7H-pyrrolo[3,2-f]quinazoline-1,3-diamine), which may significantly expand the chemical space of novel mt-DHFR inhibitors. Collectively, these observations will inform future medicinal chemistry efforts to improve the selectivity of compounds against mt-DHFR.
Engineered aluminum oxide (Al2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2) nanoparticles (NPs) are utilized in a broad range of applications; causing noticeable quantities of these materials to be released into the environment. Issues of how and where these particles are distributed into the subsurface aquatic environment remain as major challenges for those in environmental engineering. In this study, transport and retention of Al2O3, TiO2, and SiO2 NPs through various saturated porous media were investigated. Vertical columns were packed with quartz-sand, limestone, and dolomite grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolet-visible spectrophotometer. It was found that Al2O3 and TiO2 NPs are easily transported through limestone and dolomite porous media whereas NPs recoveries were achieved two times higher than those found in the quartz-sand. The highest and lowest SiO2-NPs recoveries were also achieved from the quartz-sand and limestone columns, respectively. The experimental results closely replicated the general trends predicted by the filtration and DLVO calculations. Overall, NPs mobility through a porous medium was found to be strongly dependent on NP surface charge, NP suspension stability against deposition, and porous medium surface charge and roughness.
This study investigated the dry and aqueous erosion of mild steel using electrochemical and dry sand impact techniques. In dry sand impact experiments, mild steel was eroded with 45 μm and 150 μm sand particles. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-hardness techniques were used to elaborate the surface morphology of the eroded samples. The results revealed significant change in morphology of the eroded samples. In-depth analysis showed that although the metal erosion due to larger particles was significantly higher, the fines also notably damaged the metal surface. The surface damages were appreciably reduced with decrease in impact angle of the accelerated particles. The maximum damages were observed at an impact angle of 90°. The hardness of the samples treated with 45 μm and 150 μm sand remained in the range of 88.34 to 102.31 VHN and 87.7 to 97.55 VHN, respectively. In electrochemical experiments, a triple electrode probe was added into the metal treatment process. The linear polarization resistance (LPR) measurements were performed in slurries having 5% (by weight) of sand particles. LPR of the samples treated with 45 μm and 150 μm sand slurries was calculated about 949 Ω.cm(2) and 809 Ω.cm(2), respectively.
Up to 25% of breast cancer patients in Asia present with de novo metastatic disease. We examined the survival trends of Asian patients with metastatic breast cancer over fifteen years. The impact of changes in patient's demography, tumor characteristics, tumor burden, and treatment on survival trend were examined. Patients with de novo metastatic breast cancer from three hospitals in Malaysia and Singapore (N = 856) were grouped by year of diagnosis: 1996-2000, 2001-2005 and 2006-2010. Step-wise multivariable Poisson regression was used to estimate the contribution of above-mentioned factors on the survival trend. Proportions of patients presenting with metastatic breast cancer were 10% in 1996-2000, 7% in 2001-2005, and 9% in 2006-2010. Patients in 2006-2010 were significantly older, appeared to have higher disease burden, and received more chemotherapy, endocrine therapy, and surgery of primary tumor. The three-year relative survival in the above periods were 20·6% (95% CI: 13·9%-28·2%), 28·8% (95% CI: 23·4%-34·2%), and 33·6% (95% CI: 28·8%-38·5%), respectively. Adjustment for treatment considerably attenuated the relative excess risk of mortality in recent years, compared to other factors. Substantial improvements in survival were observed in patients with de novo metastatic breast cancer in this study.
This paper presents the preparation of in situ electrodeposited rGO/MnO2 nanocomposite as a binder-free electrode for supercapacitor application. The work describes and evaluates the performance of prepared electrode via green and facile electrodeposition technique of in situ rGO/MnO2-glucose carbon nanocomposites. The carbon content in the composite electrode increased after GO and D (+) glucose solution has been added in the deposition electrolyte. This study found that a suitable concentration of D (+) glucose in the deposition electrolyte can slow down the nucleation process of MnO2 particles and lead to uniform and ultrathin nanoflakes structure. The optimize electrode exhibited low transfer resistance and resulted on excellent electrochemical performance in three electrolyte systems viz. Na2SO4, KOH and KOH/K3Fe(CN)6 redox electrolytes. The optimum energy density and power density were 1851 Whkg(-1) and 68 kWkg(-1) at current density of 20 Ag(-1) in mixed KOH/K3Fe(CN)6 electrolyte.
The whole mitochondrial genome of the pest fruit fly Bactrocera arecae was obtained from next-generation sequencing of genomic DNA. It had a total length of 15,900 bp, consisting of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a non-coding region (A + T-rich control region). The control region (952 bp) was flanked by rrnS and trnI genes. The start codons included 6 ATG, 3 ATT and 1 each of ATA, ATC, GTG and TCG. Eight TAA, two TAG, one incomplete TA and two incomplete T stop codons were represented in the protein-coding genes. The cloverleaf structure for trnS1 lacked the D-loop, and that of trnN and trnF lacked the TΨC-loop. Molecular phylogeny based on 13 protein-coding genes was concordant with 37 mitochondrial genes, with B. arecae having closest genetic affinity to B. tryoni. The subgenus Bactrocera of Dacini tribe and the Dacinae subfamily (Dacini and Ceratitidini tribes) were monophyletic. The whole mitogenome of B. arecae will serve as a useful dataset for studying the genetics, systematics and phylogenetic relationships of the many species of Bactrocera genus in particular, and tephritid fruit flies in general.
In this work, the piezoresistive effects of defective graphene used on a flexible pressure sensor are demonstrated. The graphene used was deposited at substrate temperatures of 750, 850 and 1000 °C using the hot-filament thermal chemical vapor deposition method in which the resultant graphene had different defect densities. Incorporation of the graphene as the sensing materials in sensor device showed that a linear variation in the resistance change with the applied gas pressure was obtained in the range of 0 to 50 kPa. The deposition temperature of the graphene deposited on copper foil using this technique was shown to be capable of tuning the sensitivity of the flexible graphene-based pressure sensor. We found that the sensor performance is strongly dominated by the defect density in the graphene, where graphene with the highest defect density deposited at 750 °C exhibited an almost four-fold sensitivity as compared to that deposited at 1000 °C. This effect is believed to have been contributed by the scattering of charge carriers in the graphene networks through various forms such as from the defects in the graphene lattice itself, tunneling between graphene islands, and tunneling between defect-like structures.
Langat virus (LGTV), one of the members of the tick-borne encephalitis virus (TBEV) complex, was firstly isolated from Ixodes granulatus ticks in Malaysia. However, the prevalence of LGTV in ticks in the region remains unknown. Surveillance for LGTV is therefore important and thus a tool for specific detection of LGTV is needed. In the present study, we developed a real-time quantitative reverse-transcription-polymerase chain reaction (qRT-PCR) for rapid detection of LGTV. Our findings showed that the developed qRT-PCR could detect LGTV at a titre as low as 0.1 FFU/ml. The detection limit of the qRT-PCR assay at 95% probability was 0.28 FFU/ml as determined by probit analysis (p ≤ 0.05). Besides, the designed primers and probe did not amplify ORF of the E genes for some closely related and more pathogenic viruses including TBEV, Louping ill virus, Omsk hemorrhagic fever virus (OHFV), Alkhurma virus (ALKV), Kyasanur Forest Disease virus (KFDV) and Powassan virus (POWV) which showed the acceptable specificity of the developed assay. The sensitivity of the developed method also has been confirmed by determining the LGTV in infected tick cell line as well as LGTV- spiked tick tissues.
Gut microbiota plays an important role in mammalian host metabolism and physiological functions. The functions are particularly important in young children where rapid mental and physical developments are taking place. Nevertheless, little is known about the gut microbiome and the factors that contribute to microbial variation in the gut of South East Asian children. Here, we compared the gut bacterial richness and composition of pre-adolescence in Northern Malaysia. Our subjects covered three distinct ethnic groups with relatively narrow range of socioeconomic discrepancy. These included the Malays (n = 24), Chinese (n = 17) and the Orang Asli (indigenous) (n = 20). Our results suggested a strong ethnicity and socioeconomic-linked bacterial diversity. Highest bacterial diversity was detected from the economically deprived indigenous children while the lowest diversity was recorded from the relatively wealthy Chinese children. In addition, predicted functional metagenome profiling suggested an over-representation of pathways pertinent to bacterial colonisation and chemotaxis in the former while the latter exhibited enriched gene pathways related to sugar metabolism.
The application of microfluidic devices in diagnostic systems is well-established in contemporary research. Large specific surface area of microspheres, on the other hand, has secured an important position for their use in bioanalytical assays. Herein, we report a combination of microspheres and microfluidic disk in a unique hybrid platform for highly sensitive and selective detection of dengue virus. Surface engineered polymethacrylate microspheres with carefully designed functional groups facilitate biorecognition in a multitude manner. In order to maximize the utility of the microspheres' specific surface area in biomolecular interaction, the microfluidic disk was equipped with a micromixing system. The mixing mechanism (microballoon mixing) enhances the number of molecular encounters between spheres and target analyte by accessing the entire sample volume more effectively, which subsequently results in signal amplification. Significant reduction of incubation time along with considerable lower detection limits were the prime motivations for the integration of microspheres inside the microfluidic disk. Lengthy incubations of routine analytical assays were reduced from 2 hours to 5 minutes while developed system successfully detected a few units of dengue virus. Obtained results make this hybrid microsphere-microfluidic approach to dengue detection a promising avenue for early detection of this fatal illness.
The paper deals with a stagnation-point boundary layer flow towards a permeable stretching/shrinking sheet in a nanofluid where the flow and the sheet are not aligned. We used the Buongiorno model that is based on the Brownian diffusion and thermophoresis to describe the nanofluid in this problem. The main purpose of the present paper is to examine whether the non-alignment function has the effect on the problem considered when the fluid suction and injection are imposed. It is interesting to note that the non-alignment function can ruin the symmetry of the flows and prominent in the shrinking sheet. The fluid suction will reduce the impact of the non-alignment function of the stagnation flow and the stretching/shrinking sheet but at the same time increasing the velocity profiles and the shear stress at the surface. Furthermore, the effects of the pertinent parameters such as the Brownian motion, thermophoresis, Lewis number and the suction/injection on the flow and heat transfer characteristics are also taken into consideration. The numerical results are shown in the tables and the figures. It is worth mentioning that dual solutions are found to exist for the shrinking sheet.
Cancer is a class of diseases characterized by out-of-control cells' growth which affect DNAs and make them damaged. Many treatment options for cancer exist, with the primary ones including surgery, chemotherapy, radiation therapy, hormonal therapy, targeted therapy and palliative care. Which treatments are used depends on the type, location, and grade of the cancer as well as the person's health and wishes. Chemotherapy is the use of medication (chemicals) to treat disease. More specifically, chemotherapy typically refers to the destruction of cancer cells. Considering the diffusion of drugs in cancer cells and fractality of DNA walks, in this research we worked on modelling and prediction of the effect of chemotherapy on cancer cells using Fractional Diffusion Equation (FDE). The employed methodology is useful not only for analysis of the effect of special drug and cancer considered in this research but can be expanded in case of different drugs and cancers.
With interest in the potential of optical fibres as the basis of next-generation thermoluminescence dosimeters (TLDs), the development of suitable forms of material and their fabrication has become a fast-growing endeavour. Present study focuses on three types of Ge-doped optical fibres with different structural arrangements and/or shapes, namely conventional cylindrical fibre, capillary fibre, and flat fibre, all fabricated using the same optical fibre preform. For doses from 0.5 to 8 Gy, obtained at electron and photon energies, standard thermoluminescence (TL) characteristics of the optical fibres have been the subject of detailed investigation. The results show that in collapsing the capillary fibre into a flat shape, the TL yield is increased by a factor of 5.5, the yield being also some 3.2 times greater than that of the conventional cylindrical fibre fabricated from the same perform. This suggests a means of production of suitably sensitive TLD for in-vivo dosimeter applications. Addressing the associated defects generating luminescence from each of the optical fibres, the study encompasses analysis of the TL glow curves, with computerized glow curve deconvolution (CGCD) and 2(nd) order kinetics.
Molecular detection has overcome limitations of microscopic examination by providing greater sensitivity and specificity in Plasmodium species detection. The objective of the present study was to develop a quantitative real-time polymerase chain reaction coupled with high-resolution melting (qRT-PCR-HRM) assay for rapid, accurate and simultaneous detection of all five human Plasmodium spp. A pair of primers targeted the 18S SSU rRNA gene of the Plasmodium spp. was designed for qRT-PCR-HRM assay development. Analytical sensitivity and specificity of the assay were evaluated. Samples collected from 229 malaria suspected patients recruited from Sabah, Malaysia were screened using the assay and results were compared with data obtained using PlasmoNex(TM), a hexaplex PCR system. The qRT-PCR-HRM assay was able to detect and discriminate the five Plasmodium spp. with lowest detection limits of 1-100 copy numbers without nonspecific amplifications. The detection of Plasmodium spp. in clinical samples using this assay also achieved 100% concordance with that obtained using PlasmoNex(TM). This indicated that the diagnostic sensitivity and specificity of this assay in Plasmodium spp. detection is comparable with those of PlasmoNex(TM). The qRT-PCR-HRM assay is simple, produces results in two hours and enables high-throughput screening. Thus, it is an alternative method for rapid and accurate malaria diagnosis.