Current Medical Mycology

In the present study, a new model of hybrid deep beams has been proposed and discussed. Six specimens are tested experimentally with two types of loading which are one-point and two-point loading and two hybridization models for concrete section. It is aimed from this study to search for the optimum distribution of the concrete types of the hybrid deep beams such that the lowest cost and weight to be reached with keeping the capacity without significant reduction. All specimens had the same dimensions, overall span of 1700 mm, 180 mm wide and 450 mm overall depth and the same steel reinforcement details. Results showed an increase in the capacity in the horizontal and the arched hybrid model by 27.6% and 39%, respectively, with one-point system. Moreover, toughness, enhanced by 44% and 131% for the two models respectively whereas, stiffness enhanced by 6.5% and 34.2% respectively and ductility enhanced by 0% and 31.2% respectively. For tests under two point loads, capacity enhanced by 34% and 36.9%, respectively, Toughness increased by 188% and 301% respectively. Stiffness enhanced by 7.5% and 29.4% respectively. Ductility enhanced by 40.3% and 95.1% respectively.

In this study, natural dye sensitisers derived from ketum (Mitragyna speciosa-MS), spinach (Spinacia oleracea-SO), curry (Murraya koenigii-MK), papaya (Carica papaya-CP), and henna (Lawsonia inermis-LI) were investigated for dye-sensitised solar cells (DSSCs). Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier Transform Infrared spectroscopy (FTIR), Open-Circuit Voltage Decay (OCVD) and Current to Voltage (I-V) were used to analyse the natural dye and the fabricated DSSC. It was observed that all dye solutions contain the majority of important functional groups of chlorophyll-based sensitisers, which is crucial for the dye-to-TiO2 (Titanium (II) Oxide) attachment, making them suitable sources of energy harvesting pigments. In this regard, the dye pH and chemical bonding of the respective dyes play a significant role that contribute to the overall performance of the DSSCs. It was discovered that a dye based on MK provided the best DSSC performance. This is because MK-based dye has higher content of functional groups, an optimal pH, and the slowest properties of back electron recombination among the OCVD measurements. Because of the combination of these properties, the open-circuit voltage (VOC), short-circuit current density (JSC), and power conversion efficiency (PCE) values have been determined to be 0.58 V, 2.48 mA/cm2, and 0.47%, respectively.

The mechanical properties of natural rubber (NR) vulcanizate depend strongly on several factors, i.e., vulcanization systems and crosslink density. These two parameters are originally from the formulation design of the vulcanizate. To focus more on such details, influences of three different vulcanization systems (sulfur, peroxide, and phenolic resin) with variations in their crosslink densities were studied by focusing on the change of curing properties, crosslink densities, mechanical properties and network structures of the NR vulcanizates. The crosslink density of various vulcanization systems increased with increasing curing promotors, as revealed by temperature scanning stress relaxation measurement. The tensile modulus at 100% strain increased with increasing crosslink density in all systems but the tensile strength varied with the vulcanization systems and degree of crosslink density. At the same crosslink level, the greatest tensile strength was obtained when the sulfur was used as a crosslinker, which was 100% greater than those obtained from peroxide and 200% over phenolic systems. In comparison to the phenolic resin system, sulfur and peroxide crosslink systems had a more uniform distribution of the crosslink network structure. The size of the network structure was found to be independent of the tensile strength. The peroxide system had the most uniform distribution of the crosslink network structure.  

It is reported that the membrane properties can be enhanced by nanomaterials. However, agglomeration will occur due to the overdose of nanomaterials subsequently deteriorating membrane performance. The project aims to investigate the effect of concentration of cabon nanomaterials: multiwalled carbon nanotubes (MWCNTs) and graphene oxide (GO), on nanocomposite membrane for methyl blue (MB) dye removal. The GO/MWCNTs nanocomposite membranes were synthesized using direct blending method with three concentrations (0.2, 0.5, and 1 wt.%). The synthesized membrane was characterized by surface hydrophilicity, pore size and porosity, surface charge, functional group, and surface morphology. Besides, the performance of the synthesized membrane was evaluated by water permeability test, dye rejection test, and antifouling test. The result shows that the surface hydrophilicity was enhanced when the concentration of nanomaterials increased up to 0.2 wt%. However, higher concentration of nanomaterials reduces the membrane hydrophilicity due to the agglomeration of nanomaterials. The membrane with nanomaterials concentration of 0.2 wt.% (M0.2) has the best performance as it showed 6.85% and 32% improvement in water permeability and dye rejection when compared to the pristine membrane. Besides, M0.2 membrane has relatively good antifouling properties indicated by normalized flux (0.8043). This is due to the enhancement of hydrophilicity and zeta potential of M0.2 membrane by carbon nanomaterials. In short, optimum concentration of carbon nanomaterials are essential to enhance the membrane performance as agglomeration of nanomaterials occurs at high concentration.

Spent bleaching earth ash (SBEA) is harmful waste from the oil refining industry that has previously exhibited pozzolanic properties and potential for use as cement replacement. Conventional pozzolanic replacements in cements are typically limited to 30 % only as excessive amounts have detrimental on cement strength. This research aimed to investigate the feasibility of increasing the level of replacement past 30 % through mechanical activation. Preliminary investigations revealed that SBEA contains sufficient silica and alumina oxides to be classified as Class N pozzolan in accordance with ASTM C618. As expected with pozzolans, the use of SBEA in cement mortar improved the 28 and 56-day compressive strengths up to 30 % substitution but at the same time also increased the water requirement. Mechanical activation was able to improve the level of substitution to 50 % through a mix of increasing pozzolanic reactivity of SBEA as well as increasing the specific surface area of its particles.

Kombucha is a fermented beverage that is prepared traditionally by fermenting Symbiotic Culture of Bacteria and Yeast (SCOBY) with sugar and black/green tea, which is known as Camellia sinensis leaves. The previous study analyses the microbial composition that can be obtained in Kombucha production. Study shows that yeast species and acetic acid bacteria (AAB) species are the microorganisms that involve in the fermentation process of Kombucha. Some studies emphasize the chemical composition that was obtained from the production of Kombucha drinks such as organic acids, sugars, ethanol, and polyphenols. However, further review and elucidation regarding the substrates used and metabolic activity in Kombucha fermentation is necessary. Thus, the objective of this study is to review the metabolic pathway and substrates involve in Symbiotic Culture of Bacteria and Yeast (SCOBY) fermentation. This review also collected information related to the symbiosis of fermentation by yeast and AAB pathway in Kombucha fermentation. Several pharmaceutical effects of Kombucha were also discussed to prove the health benefits of Kombucha. To produce good quality and high yield of Kombucha that can provide various health benefits to consumers, it is crucial to understand the connection between the metabolic activity with Symbiotic Culture of Bacteria and Yeast (SCOBY) during the fermentation process of Kombucha. By conducting this review work, it could provide an insightful overview and better understanding of metabolic pathways and substrates involved in SCOBY and Kombucha fermentation.

Cellulose nanocrystasl (CNC) were produced from oil palm empty fruit bunch (EFB) and pineapple leaf fibre (PALF) using double oxidation treatment comprising bleaching and ammonium persulfate (APS) treatments. Different techniques were used to characterise the extracted CNC. Fourier transform infrared (FTIR) spectra confirmed the formation of carboxyl group and decreasing fractions of non-cellulosic components. The CNCs from both fibres show a better crystallinity index than the raw fibre, and the CNCs also conform to the crystalline structure of cellulose I. Morphology analysis using transmission electron microscopy (TEM) reveals that the CNCs of EFB and PALF have different shapes and dimensions. Spherical EFB had a 16.33 ± 8.5 nm diameter, while rod-like PALF had 13.07 ± 6.15 nm and 78.67 ± 38.07 nm diameter and length. However, the thermal stability of both CNCs decreased slightly. Hence, the findings indicate that the double oxidation approach using agricultural biomass wastes can work as an alternative route for the preparation of CNCs.

ABS filament remains an important feeding material for fused deposition manufacturing (FDM). However, ABS tends to experience warping after printing. The current paper investigates the effect of hBN fill on rheology property and diameter of ABS extrudate. ABS filled hBN composite was prepared by a facile solution mixing method. Rheological characterisation by capillary rheometer shows that ABS filled 5 wt% hBN composite exhibited a higher shear viscosity than the pure ABS. hBN addition appears to increase the shear viscosity of ABS by 62% at the shear rate of 200 s-1, but the increase was reduced to 20% at 1000 s-1. ABS-hBN extrudate surface microstructure deteriorated lesser than ABS extrudate when the shear rate increased up to 1000s-1. SEM micrograph of ABS-hBN extrudate’s surface exhibited less sharkskin feature but its swell percentage is 5.4% higher than the ABS extrudate. The addition of hBN fillers resulted in higher shear viscosity and percentage of ABS die swell but exhibited less sharkfin feature (smoother surface) on extrudate surface than the pure ABS.

The placement of tidal turbines in a tidal farm is challenging owing to the flow resistance caused by individual devices. To successfully deploy tidal turbines, the wake interaction between devices, often determined by the array's layout and spacing, must be understood. In this study, the impact of array configuration for shallow water application is examined numerically using computational fluid dynamics (CFD). This is to propose a suitable array structure for possible implementation in Malaysia. This numerical study uses 15 turbines in a staggered and squared array with two sets of lateral and longitudinal spacing combinations. The horizontal axis tidal turbine (HATT) and vertical axis tidal turbine (VATT) are represented using disc and cylindrical models, respectively. The VATT with staggered setup and greater spacing model demonstrates faster wake recovery (between 10% to 21%), compared to the squared arrangement. This meets the far wake criteria and reduces the chance of wake mixing. It is also suitable for shallow depth implementation.

The choice of estimation technique according to geological conditions and mineralization character is the main problem in estimating block grade of nickel laterite. CV (coefficient of variance) and variogram determine the choice of estimation technique for nickel laterite resource classification. This study aims to evaluate various techniques for estimating block grades and to select the appropriate method for the classification of nickel laterite resources. The basic statistical analysis is to find out the description of the data, while the variography is to find out the spatial correlation between the data. Nickel grade estimation results are based on Near Neighbor Polygon (NNP), Inverse Distance Weighting (IDW), and Ordinary Kriging (OK) techniques to determine the classification of nickel resources. Accuracy levels are based on cross-sectional visualization comparisons, plan views, probability plots and linear regression analysis. The OK technique were not superior in grade estimation, especially in nickel laterite deposits. The results showed that the IDW technique was suitable to be applied to the limonite zone, while the NNP technique was suitable to be applied to the saprolite zone. Based on the performance of the estimation technique, the weighted average method can be applied for the classification of inferred, indicated, and measurable resources. The grade-tonnage curve shows the nickel laterite resource potential in the study area.

Crack formation in concrete is inevitable. The cracks allow the penetration of harmful substances which may decrease the durability and the service life of concrete structures. Self-healing concrete is therefore emerging as an innovative construction material to tackle the cracking issues. In recent years, microbial self-healing concrete is garnering interest from many researchers due to its environmentally-friendly nature and the concrete compatibility of microbially-induced calcium carbonate precipitation. Various metabolic mechanisms have been used for microbial self-healing concrete production and urea hydrolysis is the most preferable metabolic pathway due to its fast and high precipitation of calcium carbonate. In this paper, a comprehensive review on the research progress on microbial self-healing concrete is presented together with the numerical modelling of microbial self-healing concrete. The challenges and limitations of microbial self-healing concrete are discussed along with the recommendations for its prospective uses in the construction industry. It is found that the survival of bacteria through direct addition technique is limited and needs further investigation. The immobilization technique gives a promising result in durability properties but doesn’t reach the mechanical requirement. Moreover, a comprehensive assessment of self-healing efficiency is required, and more efforts are needed to improve from laboratory scale to large-scaled application.

Adsorption has been a feasible process to remove dye molecules from water resources. However, some of the proposed adsorbents required high temperature to be synthesized or hard to be separated towards the end of their applications. Realizing this, this study aims to fabricate Fe3O4-decorated sand that does not require high temperature in production. More importantly, the attached Fe3O4 nanoparticles provide intrinsic magnetic properties to ease the subsequent separation. The ability of this adsorbent to remove methylene blue (cationic dye), tartrazine (anionic dye), and disperse yellow 3 (non-ionic dye) at different medium pHs were investigated. Results showed that the Fe3O4-decorated sand performed better in dye removal as compared to the pure sand counterpart. In specific, sand doped with 5000 mg/L of Fe3O4 successfully removed 75.01 % of methylene blue, as compared to the 68.01 % achieved by using pure sand alone. It was also found that the effectiveness of dye adsorption and desorption strongly depends on the medium pH mostly due to the amphoteric nature of the Fe3O4 nanoparticles. The desorption of methylene blue, tartrazine, and disperse yellow 3 from the adsorbent best to be done using 30 % v/v acetone, 0.1 M NaOH, and 30 % v/v ethanol, respectively. Additionally, it was found that this adsorbent can be effectively separated using either high or low gradient magnetic fields.

Glucose is a cheap and readily available substrate for production of large-scale chemicals. Synthesis of xylitol, a high demand chemical in global market is currently done by using xylose, which contributes to its high operational cost. Studies on production of xylitol from glucose have explored several approaches, from sequential fermentation to multiple and single gene expression. Xylitol-5-phosphate dehydrogenase (XPDH), is an enzyme that enables conversion of glucose to xylitol in a single step fermentation. This study explores conversion of xylitol from glucose in E. coli by the expression of xpdh from Clostridium difficile with modifications in metabolic pathways to enhance xylitol production. The xpdh gene was carried by pACYC-Duet-1 expression vector and induced by the addition of IPTG. Initial screening of E. coli expressing xpdh (NA116) was done by shake-flask fermentation for 24 hours and its metabolites were analyzed by HPLC. NA116 was able to produce 0.273 g/L xylitol from 4.33 g/L consumed glucose in 24 hours. Further metabolic pathway modification to eliminate competing pathways yielded four mutants, NA207 (∆rpiA), NA208 (∆rpiB), NA209 (∆pgi) and NA211 (∆rpi∆Apgi). Screening of mutants for xylitol production showed that highest xylitol production from glucose was achieved by NA211 with almost double the amount of the original strain, 0.585 g/L. This showed successful xylitol conversion from glucose in a single fermentation in E. coli with improved yield through metabolic pathway modification.

In order to reduce the continual depletion and exploitation of natural resources, this paper examines the mechanical properties and fracture prediction of sustainable lightweight aggregates concretes comprising agro-industrial waste or/and artificial aggregate, considering a full replacement of conventional coarse aggregate. The fresh and hardened properties are examined, from which three out of the five design mixes can achieve structural concrete specifications. It is observed that compression, tensile, and flexural strengths of the mixes exhibit a similar behaviour trend, as relatively higher values can be obtained from homogenous coarse aggregates compared to heterogeneous aggregates for different proportions of oil palm shell (OPS) and expanded clay replacement. The experimental results showed compression strength of 13 to 32 MPa, splitting tensile strength of 1.32 to 2.97 MPa and flexural strength of 1.67 to 5.24 MPa for the investigated mixes at concrete age of 28 day. Most of the mixes able to achieve structural use. Amongst the mixes, those containing expanded clay lowered the corresponding sorptivity values. Although statistics prove that the prediction models of tensile and flexural strengths can represent existing experimental findings, further investigations are recommended for a better properties forecasting of lightweight aggregate concrete containing OPS and expanded clay.

This study investigated effect of virgin coconut oil (VCO)-derived fatty acids on the alteration of lipid profiles and liver tissues of high fat diet (HFD) fed mice. The initial fatty acids mixture was successfully obtained via hydrolysis process using Candida rugosa lipase (CRL). Enrichment of medium chain fatty acids (MCFA) from the initial fatty acid mixture using distillation process was developed to achieve 3 fractions of fatty acids mixture including Fraction I (MCFA mainly from C8 to C10), Fraction II of lauric acid (C12), and Fraction III (long chain fatty acids from C14 to C20). Among these agents, VCO only diminished ALT level but the initial FFA mixture decreased both ALT and AST levels compared with HFD-induced mice. Moreover, Fraction I and Fraction II showed an obvious difference in decreasing ALT, AST, total cholesterol, and LDL cholesterol levels as well as increasing HDL cholesterol level compared to other agents. It was observed a microvesicular steatosis and mild inflammation in liver section of mice fed with HFD whereas VCO, initial fatty acids, and Fraction II showed the beneficial effect on liver damage.