The purpose of this study was to produce a novel pH sensitive hydrogel with superior thermal stability, composed of
poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali
and bleaching treatments followed by acid hydrolysis. PAA was then subjected to chemical cross-linking using the crosslinking
agent (N,N-methylenebisacrylamide) in CNC suspension. The mixture was casted onto petri dish to obtain disc
shape hydrogel. PAA/cellulose hydrogel with the same composition ratio were also prepared as control. The effect of
reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH
was studied. The obtained hydrogel was further subjected to different tests such as thermogravimetric analysis (TGA) to
study the thermal behavior, Fourier transform infrared for functional group identification and swelling test for swelling
behavior at different pH. The cross-linking of PAA was verified with FTIR with the absence of C=C double bond. In TGA
test, PAA/CNC hydrogel showed significantly higher thermal stability compared with pure PAA hydrogel. The hydrogel
obtained showed excellent pH sensitivity and experienced maximum swelling at pH7. The PAA/CNC hydrogel can be
developed further as drug carrier
Red mud as industrial waste from bauxite was utilized as a precursor for the synthesis of mesoporous ZSM-5. A high concentration of iron oxide in red mud was successfully removed using alkali fusion treatment. Mesoporous ZSM-5 was synthesized using cetyltrimethylammonium bromide (CTABr) as a template via dual-hydrothermal method, and the effect of crystallization time was investigated towards the formation of mesopores. Characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicated the formation of cubic crystallite ZSM-5 with high surface area and mesopore volume within 6 h of crystallization. Increasing the crystallization time revealed the evolution of highly crystalline ZSM-5; however, the surface area and mesoporosity were significantly reduced. The effect of mesoporosity was investigated on the adsorption of methylene blue (MB). Kinetic and thermodynamic analysis of MB adsorption on mesoporous ZSM-5 was carried out at a variation of adsorption parameters such as the concentration of MB solution, the temperatures of solution, and the amount of adsorbent. Finally, methanol, 1-butanol, acetone, hydrochloric acid (HCl), and acetonitrile were used as desorbing agents to investigate the reusability and stability of mesoporous ZSM-5 as an adsorbent for MB removal.
The use of rice husks (RH) to reinforce polymers in biocomposites are increasing tremendously. However, the incompatibility between the hydrophilic RH fibers and the hydrophobic thermoplastic matrices leads to unsatisfactory biocomposites. Surface modification of the fiber surface was carried out to improve the adhesion between fiber and matrix. In this study, the effect of surface modification of RH via alkali, acid and ultraviolet-ozonolysis (UV/O3) treatments on the properties of composites recycled high density polyethylene (rHDPE) composites was investigated. The untreated and treated RH were characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM). The composites containing 30 wt% of RH (treated and untreated) were then prepared via extrusion and followed by compression molding. As compared to untreated RH, all surface treated RH exhibited rougher surface and showed improved adhesion with rHDPE matrix. Tensile strength of UV/O3-treated RH composites showed an optimum result at 18.37 MPa which improved about 5% in comparison to the composites filled with untreated RH. UV/O3 treatment promotes shorter processing time and lesser raw material waste during treatment process where this is beneficial for commercialization in the future developments of wood plastic composites (WPCs). Therefore, UV/O3 treatment can be served as an alternative new method to modify RH surface in order to improve the adhesion between hydrophilic RH fibre and hydrophobic rHDPE polymer matrix.
Saline-alkali soil has become an important environmental problem for crop productivity. One of the most effective approaches is to cultivate new stress-tolerant plants through genetic engineering. Through RNA-seq analysis and RT-PCR validation, a novel bZIP transcription factor ChbZIP1, which is significantly upregulated at alkali conditions, was obtained from alkaliphilic microalgae Chlorella sp. BLD. Overexpression of ChbZIP1 in Saccharomyces cerevisiae and Arabidopsis increased their alkali resistance, indicating ChbZIP1 may play important roles in alkali stress response. Through subcellular localization and transcriptional activation activity analyses, we found that ChbZIP1 is a nuclear-localized bZIP TF with transactivation activity to bind with the motif of G-box 2 (TGACGT). Functional analysis found that genes such as GPX1, DOX1, CAT2, and EMB, which contained G-box 2 and were associated with oxidative stress, were significantly upregulated in Arabidopsis with ChbZIP1 overexpression. The antioxidant ability was also enhanced in transgenic Arabidopsis. These results indicate that ChbZIP1 might mediate plant adaptation to alkali stress through the active oxygen detoxification pathway. Thus, ChbZIP1 may contribute to genetically improving plants' tolerance to alkali stress.
This paper studied the thermal behaviour of pineapple leaf fibre (PALF) reinforced high impact polystyrene (HIPS) composite. Thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis were used to measure the thermal characteristic of HIPS/PALF composites. In particular, the TGA analysis was utilized to measure the degradation and decomposition of materials in neat polystyrene, pineapple fibre, and the composites. The measurements were carried out in the temperature of 25°C – 800°C, at a heating rate of 20°C min-1 and the nitrogen gas flow was 50 mL min-1. The temperature of the DSC analysis was programmed to be between 25°C – 300°C. The results from TGA analysis show that the addition of pineapple fibre has improved the thermal stability of the composites as compared to neat HIPS. In addition, the effects of compatibilising agent and surface modification of PALF with alkali treated were also determined and compared.
This paper presents the solution to a calculation of the pH of a very dilute solution of a strong acid or base, taking into account the effect of the hydronium or hydroxyl ions generated from the ionisation of the strong acid or base on the ionisation of water, as a second very weak acid. To be solved successfully, this calculation involves the concepts of conservation of charge, pH and the application of the general solution to a quadratic equation. Such an exercise involves the application of skills in basic numeracy, and can provide a core of understanding that can prepare students for
many different sorts of calculations that represent reallife problems in the medical and biological sciences.A programme is presented in C++ which enables the work of students to be individualised so that each student in a class can work through a slightly different pH calculation, in such a way that a class supervisor can quickly check each student’s result for accuracy. This exercise is presented as a potential means of enabling students to undertake and master similar types of calculations involving simple or more complex equilibria.
In this study, the selenium enriched peanuts and the different solubility proteins extracted from them were investigated. The dried defatted selenium enriched peanuts (SeP) powder (0.3147 μg/g) had a 2.5-fold higher mean total selenium concentration than general peanuts (GP) power (0.1233 μg/g). The SeP had higher concentration of selenium, manganese and zinc than that of GP, but less calcium. The rate of extraction of protein was 23.39% for peanuts and alkali soluble protein was the main component of protein in SeP, which accounted for 92.82% of total soluble protein and combined selenium was 77.33% of total selenium protein. In different forms of proteins from SeP, the WSePr due to higher concentration of selenium had higher DPPH free-radical scavenging activity, higher reducing activity and longer induction time than other proteins.
The main focus of this study was to obtain the optimum alkaline treatment for banana fibre and the its effect on the mechanical and chemical properties of banana fibre, its surface topography, its heat resistivity, as well as its interfacial bonding with epoxy matrix. Banana fibre was treated with sodium hydroxide (NaOH) under various treatment conditions. The treated fibres were characterised using FTIR spectroscopy. The morphology of a single fibre observed under a Digital Image Analyser indicated slight reduction in fibre diameter with increasing NaOH concentration. The Scanning Electron Microscope (SEM) results showed the deteriorating effect of alkali, which can be seen from the removal of impurities and increment in surface roughness. The mechanical analysis indicates that 6% NaOH treatment with a two-hour immersion time gave the highest tensile strength. The adhesion between single fibre and epoxy resin was analysed through the micro-droplet test. It was found that 6% NaOH treatment with a two-hour immersion yielded the highest interfacial shear stress of 3.96 MPa. The TGA analysis implies that alkaline treatment improved the thermal and heat resistivity of the fibre.
The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).
Lithium, the lightest natural-occurring alkali metal with an atomic number of three, stabilizes the mood to prevent episodes of acute manic and depression. Multiple lines of evidence point to lithium as an anti-suicidal, anti-viral, anti-cancer, immunomodulatory, neuroprotective and osteoprotective agent. This review article provides a comprehensive review of studies investigating the bone-enhancing effects of lithium and its possible underlying molecular mechanisms. Most of the animal experimental studies reported the beneficial effects of lithium in defective bones but not in healthy bones. In humans, the effects of lithium on bones remain heterogeneous. Mechanistically, lithium promotes osteoblastic activities by activating canonical Wingless (Wnt)/beta (β)-catenin, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and bone morphogenetic protein-2 (BMP-2) transduction pathways but suppresses osteoclastic activities by inhibiting the receptor activator of nuclear factor-kappa B (RANK)/receptor activator of nuclear factor-kappa B ligand (RANKL)/osteoprotegerin (OPG) system, nuclear factor-kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and calcium signaling cascades. In conclusion, lithium confers protection to the skeleton but its clinical utility awaits further validation from human clinical trials.
Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. One of the methods involves using geopolymer technology. On this basis, this current research focuses on the inter-particle effect on the properties of fly ash geopolymer aggregates with different molarities of sodium hydroxide (NaOH). The effects of synthesis parameters (6, 8, 10, 12, and 14 M) on the mechanical and microstructural properties of the fly ash geopolymer aggregate were studied. The fly ash geopolymer aggregate was palletized manually by using a hand to form a sphere-shaped aggregate where the ratio of NaOH/Na2SiO3 used was constant at 2.5. The results indicated that the NaOH molarity has a significant effect on the impact strength of a fly ash geopolymer aggregate. The highest aggregate impact value (AIV) was obtained for samples with 6 M NaOH molarity (26.95%), indicating the lowest strength among other molarities studied and the lowest density of 2150 kg/m3. The low concentration of sodium hydroxide in the alkali activator solution resulted in the dissolution of fly ash being limited; thus, the inter-particle volume cannot be fully filled by the precipitated gels.
Synthetic fibers such as glass fiber and carbon fiber are traditionally used as reinforcement in engineering composites. The increasing of environmental concerns has led to the use of natural fibers as renewable alternatives reinforcement. Among them, coconut meat husk fiber which abundant availability can be used as reinforcement fiber. However, the coconut meat husk fiber, same as other natural fibers, has the issues of fiber/matrix bonding and moisture absorption. Chemical treatments are needed to modify the surface of fiber, aiming at improving the adhesion with polymer matrix and reducing the hydrophilicity of the fiber. Alkalization was used in this study to treat the coconut meat husk fiber. The effects of chemical treatments for 1hr and 24 hr treatment time on the coconut meat husk fibers reinforced composites were investigated. A result showed that the 24 hr alkali treatment gave the highest tensile stenght compared to the 1hr treatment and RO water.
Methyl esters from vegetable oils have attracted a great deal of interest as substitute for petrodiesel to reduce dependence on imported petroleum and provide an alternate and sustainable source for fuel with more benign environmental properties. In the present study biodiesel was prepared from sunflower seed oil by transesterification by alkali-catalyzed methanolysis. The fuel properties of sunflower oil biodiesel were determined and discussed in the light of ASTM D6751 standards for biodiesel. The sunflower oil biodiesel was chemically characterized with analytical techniques like FT-IR, and NMR ((1)H and (13)C). The chemical composition of sunflower oil biodiesel was determined by GC-MS. Various fatty acid methyl esters (FAMEs) were identified by retention time data and verified by mass fragmentation patterns. The percentage conversion of triglycerides to the corresponding methyl esters determined by (1)H NMR was 87.33% which was quite in good agreement with the practically observed yield of 85.1%.
Six new Pd(II) and Ni(II) metal complexes of N, O-bidentate (L1, L2) and ONNO-tetradentate (L3) Schiff base ligands have been synthesized. The compounds were characterized via various physicochemical and spectroscopic techniques namely elemental analysis (CHN), FT-IR, 1H and 13C NMR as well as magnetic susceptibility measurement. All complexes showed diamagnetism indicating that they are square planar complexes. Catalytic performance of Pd(L1)2 and Pd(L2)2 were investigated for Heck cross-coupling reaction under optimum operating parameters, monitored using GC-FID for 6 h of reaction time in inert conditions. High catalytic activities of up to 90% were observed in the presence of triethylamine as base and DMA as solvent at 100oC with 1 mmol% catalyst loading. The mechanism of catalyzed Heck reaction is proposed to go through a series of conversion of Pd(0)/Pd(II).
Pengimejan tradisi mempunyai banyak kekurangan seperti mempunyai jangka hayat yang pendek serta bersaiz besar
kerana sifat pendafluornya tidak tahan lama atau berlakunya pelunturanfoto. Melalui kajian ini, nanohablur kadmium
sulfida dihasilkan dan berfungsi sebagai pengimejan titik kuantum yang sesuai dengan sifat optiknya yang pelbagai
mengikut saiz zarahnya. Sifat optik titik kuantum kadmium sulfida (TK CdS) boleh dipengaruhi oleh saiz dan juga
komposisi kimia TK seperti perubahan pH. Dalam kajian ini, sifat optik TK CdS dikaji terhadap perubahan nilai pH
dengan menghasilkan TK CdS melalui kaedah koloidal. Kadmium asetat dihidrat (C4
H6
CdO4
.2H2
O) dan natrium sulfida
(Na2
S) digunakan sebagai sebagai bahan pemula bagi menghasilkan TK CdS. Nilai pH diubah suai dengan menitiskan
natrium hidroksida (NaOH) ke dalam larutan TK CdS. Lima jenis larutan disediakan iaitu pada nilai pH5, pH7, pH8,
pH9 dan pH10. Masalah penggumpalan sering berlaku semasa proses sintesis CdS. Oleh itu, kajian ini menggunakan
asid tioglikolik (HSCH2
CO2
H) sebagai agen penstabil kepada TK CdS. Spektra keserapan UV memberi anjakan biru
apabila TK CdS pada pH alkali kerana saiz nanohablur mengecil. Hasil daripada spektroskopi pendarfluor mendapati
larutan yang mempunyai nilai pH8 memberi puncak yang tertinggi. Hal ini adalah kerana pada pH ini nanohablur
mampu berubah pada posisi yang tepat dan membentuk TK CdS pada kehabluran yang tinggi. Oleh itu, mekanisme ini
dapat membentuk perangkap lubang dan seterusnya eksiton terbentuk.
This paper presents the findings of a study on solidification/stabilization (S/S) of lead-contaminated soil using ordinary Portland cement (OPC) and rice husk ash (RHA). The effects of varying lead concentrations (in the form of nitrates) in soil samples on the physical properties of their stabilized forms, namely unconfined compressive strength (UCS), setting times of early mixtures and changes in crystalline phases as well as chemical properties such as leachability of lead, pH and alkalinity of leachates are studied. Results have indicated that usage of OPC with RHA as an overall binder system for S/S of lead-contaminated soils is more favorable in reducing the leachability of lead from the treated samples than a binder system with standalone OPC. On the other hand, partial replacement of OPC with RHA in the binder system has reduced the UCS of solidified samples.
This study examined the potential of untreated and alkali-pretreated sugarcane bagasse (SCB) in cellulase, reducing sugar (RS) and fungal biomass production via solid state fermentation (SSF) using Pycnoporus sanguineus. The impact of the composition, structure and cellulase adsorption ability of SCB on the production of cellulase, RS and fungal biomass was investigated. From the morphological and compositional analyses, untreated SCB has relatively more structural changes with a higher percentage of depolymerisation on the cellulose, hemicellulose and lignin content compared to alkali-pretreated SCB. Thus, untreated SCB favoured the production of cellulase and fungal biomass whereas alkali-pretreated SCB yielded a higher amount of RS. The composition and morphology of untreated SCB did not encourage RS production and this suggested that RS produced during SSF might be consumed in a faster rate by the more abundantly grown fungus. Besides that, alkali-pretreated SCB with higher cellulase adsorption ability could have adsorbed the cellulase produced and resulted in a lower cellulase titre. In short, the production of specific bioproducts via SSF is dependent on the structure and composition of the substrate applied.
High alkaline environment can lead to respiratory alkalosis and ammonia toxification to freshwater fish. However, the Amur ide (Leuciscus waleckii), which inhabits an extremely alkaline lake in China with titratable alkalinity up to 53.57 mM (pH 9.6) has developed special physiological and molecular mechanisms to adapt to such an environment. Nevertheless, how the Amur ide can maintain acid-base balance and perform ammonia detoxification effectively remains unclear. Therefore, this study was designed to study the ammonia excretion rate (Tamm), total nitrogen accumulation in blood and tissues, including identification, expression, and localization of ammonia-related transporters in gills of both the alkali and freshwater forms of the Amur ide. The results showed that the freshwater form Amur ide does not have a perfect ammonia excretion mechanism exposed to high-alkaline condition. Nevertheless, the alkali form of Amur ide was able to excrete ammonia better than freshwater from Amur ide, which was facilitated by the ionocytes transporters (Rhbg, Rhcg1, Na+/H+ exchanger 2 (NHE2), and V-type H+ ATPase (VHA)) in the gills. Converting ammonia into urea served as an ammonia detoxication strategy to reduced endogenous ammonia accumulation under high-alkaline environment.
Biodiesel with improved yield was produced from microalgae biomass under simultaneous cooling and microwave heating (SCMH). Nannochloropsis sp. and Tetraselmis sp. which were known to contain higher lipid species were used. The yield obtained using this novel technique was compared with the conventional heating (CH) and microwave heating (MWH) as the control method. The results revealed that the yields obtained using the novel SCMH were higher; Nannochloropsis sp. (83.33%) and Tetraselmis sp. (77.14%) than the control methods. Maximum yields were obtained using SCMH when the microwave was set at 50°C, 800W, 16h of reaction with simultaneous cooling at 15°C; and water content and lipid to methanol ratio in reaction mixture was kept to 0 and 1:12 respectively. GC analysis depicted that the biodiesel produced from this technique has lower carbon components (<19 C) and has both reasonable CN and IV reflecting good ignition and lubricating properties.
Various pretreatments on Ceiba pentandra (L.) Gaertn. (kapok) fiber prior to enzymatic hydrolysis for sugar production were optimized in this study. The optimum conditions for water, acid, and alkaline pretreatments were 170°C for 45 min, 120°C for 45 min in 1.0% (v/v) H2SO4 solution and 120°C for 60 min in 2.0% (v/v) NaOH solution, respectively. Among the three pretreatments, the alkaline pretreatment achieved the highest total glucose yield (glucose yield calculated based on the untreated fiber) (38.5%), followed by the water (35.0%) and acid (32.8%) pretreatments. As a result, the relative effectiveness of the pretreatment methods for kapok fiber was verified as alkali>water>acid at the condition stated.