High demands on low-voltage electronics have increased the need for zinc oxide (ZnO) varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synthesis mechanism for obtaining praseodymium oxide (Pr(6)O(11)) based ZnO varistor ceramics having breakdown voltages of 2.8 to 13.3 V/mm through employment of direct modified citrate gel coating technique. Precursor powder and its ceramics were examined by means of TG/DTG, FTIR, XRD and FESEM analyses. The electrical properties as a function of Pr(6)O(11) addition were analyzed on the basis of I-V characteristic measurement. The breakdown voltage could be adjusted from 0.01 to 0.06 V per grain boundary by controlling the amount of Pr(6)O(11) from 0.2 to 0.8 mol%, without alteration of the grain size. The non-linearity coefficient, α, varied from 3.0 to 3.5 and the barrier height ranged from 0.56 to 0.64 eV. Breakdown voltage and α lowering with increasing Pr(6)O(11) content were associated to reduction in the barrier height caused by variation in O vacancies at grain boundary.
The partitioning of β-mannanase derived from Bacillus subtilis ATCC 11774 in aqueous two-phase system (ATPS) was studied. The ATPS containing different molecular weight of polyethylene glycol (PEG) and types of salt were employed in this study. The PEG/salt composition for the partitioning of β-mannanase was optimized using response surface methodology. The study demonstrated that ATPS consists of 25% (w/w) of PEG 6000 and 12.52% (w/w) of potassium citrate is the optimum composition for the purification of β-mannanase with a purification fold (PF) of 2.28 and partition coefficient (K) of 1.14. The study on influences of pH and crude loading showed that ATPS with pH 8.0 and 1.5% (w/w) of crude loading gave highest PF of 3.1. To enhance the partitioning of β-mannanase, four ionic liquids namely 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4), 1-butyl-3-methylimidazolium bromide ([Bmim]Br), 1-ethyl-3-methylimidazolium bromide ([Emim]Br) was added into the system as an adjuvant. The highest recovery yield (89.65%) was obtained with addition of 3% (w/w) of [Bmim]BF4. The SDS-PAGE analysis revealed that the β-mannanase was successfully recovered in the top phase of ATPS with the molecular size of 36.7kDa. Therefore, ATPS demonstrated a simple and efficient approach for recovery and purification of β-mannanase from fermentation broth in one single-step strategy.
The effectiveness of sodium citrate and sodium citrate/ranitidine were compared in two randomised groups of elective caesarean patients during the various phases of anaesthesia. The mean pH values (3.5, 3.3, 3.6) were lower in the citrate group compared to the citrate/ranitidine group (6.1, 6.3, 5.9). The percentage of patients with pH values less than 2.5 was 40% in the citrate group compared to 7% in the citrate/ranitidine group. Sodium citrate alone is less effective than sodium citrate/ranitidine for acid aspiration prophylaxis.
Obesity is one of the pandemic chronic diseases commonly associated with health disorders such as heart attack, high blood pressure, diabetes or even cancer. Among the current natural products for obesity and weight control, Garcinia or more specifically hydroxycitric acid (HCA) extracted from Garcinia has been widely used. The evaluation of the potential toxicity of weight control supplement is of the utmost importance as it requires long term continuous consumption in order to maintain its effects. Majority of reports demonstrated the efficacy of Garcinia/HCA without any toxicity found. However, a few clinical toxicity reports on weight-loss diet supplements of which some were combinations that included Garcinia/HCA as an active ingredient showed potential toxicity towards spermatogenesis. Nonetheless, it cannot be concluded that Garcinia/HCA is unsafe. Those products which have been reported to possess adverse effects are either polyherbal or multi-component in nature. To date, there is no case study or report showing the direct adverse effect of HCA. The structure, mechanism of action, long history of the use of Garcinia/HCA and comprehensive scientific evidence had shown "no observed adverse effect level (NOAEL)" at levels up to 2800 mg/day, suggesting its safety for use.
Garcinia is a plant under the family of Clusiaceae that is commonly used as a flavouring agent. Various phytochemicals including flavonoids and organic acid have been identified in this plant. Among all types of organic acids, hydroxycitric acid or more specifically (-)-hydroxycitric acid has been identified as a potential supplement for weight management and as antiobesity agent. Various in vivo studies have contributed to the understanding of the anti-obesity effects of Garcinia/hydroxycitric acid via regulation of serotonin level and glucose uptake. Besides, it also helps to enhance fat oxidation while reducing de novo lipogenesis. However, results from clinical studies showed both negative and positive antiobesity effects of Garcinia/hydroxycitric acid. This review was prepared to summarise the update of chemical constituents, significance of in vivo/clinical anti-obesity effects, and the importance of the current market potential of Garcinia/hydroxycitric acid.
The aims of this study were to fabricate cellulose acetate (CA) film from oil palm empty fruit bunch (OP-EPB), as well as to characterize and evaluate their biocompatibility. Several processes were carried out, and these included prehydrolysis-soda method, chlorine free bleaching method, including oxygen, ozone and peroxide, to produce the cellulose pulp. Then, a liquid phase acetylation method was applied through acetic acid-acetic anhydride-sulphuric acid. Triethyl citrate (TEC) ester was used as additive at different percentages of 10, 20, 30 and 40 wt%. The film produced was characterized by FTIR to identify the functional group of the CA film and their tensile properties were further characterized. Biocompatibility of the film was evaluated using cytotoxicity test. Stem cell derived from human deciduous teeth (SHED) was used with MTS assay. The results showed at 30% of TEC, the tensile strength and elongation of CA (OP-EFB) film was at the optimum and is therefore suitable to be used in dental application. The cytotoxicity evaluated showed that the fabricated CA (OP-EFB) films were non-toxic up to the concentration tested, and are thus compatible with SHED.
The giant freshwater prawn holds a significant position as a valuable crustacean species cultivated in the aquaculture industry, particularly well-known and demanded among the Southeast Asian countries. Aquaculture production of this species has been impacted by Macrobrachium rosenbergii nodavirus (MrNV) infection, which particularly affects the larvae and post-larvae stages of the prawn. The infection has been recorded to cause mortality rates of up to 100% among the affected prawns. A simple, fast, and easy to deploy on-site detection or diagnostic method is crucial for early detection of MrNV to control the disease outbreak. In the present study, novel single-stranded DNA aptamers targeting the MrNV capsid protein were identified using the systematic evolution of ligands by exponential enrichment (SELEX) approach. The aptamer was then conjugated with the citrate-capped gold nanoparticles (AuNPs), and the sensitivity of this AuNP-based aptasensor for the detection of MrNV capsid protein was evaluated. Findings revealed that the aptamer candidate, APT-MrNV-CP-1 was enriched throughout the SELEX cycle 4, 9, and 12 with the sequence percentage of 1.76%, 9.09%, and 12.42%, respectively. The conjugation of APT-MrNV-CP-1 with citrate-capped AuNPs exhibited the highest sensitivity in detecting the MrNV capsid protein, where the presence of 62.5 nM of the viral capsid protein led to a significant agglomeration of the AuNPs. This study demonstrated the practicality of an AuNP-based aptasensor for disease diagnosis, particularly for detecting MrNV infection in giant freshwater prawns.
OBJECTIVES: To investigate the correlations and agreements between the solute/creatinine ratios from the 24-hour and early morning spot urine samples for metabolic evaluation in stone-formers given the various pitfalls with the 24-hour urinary metabolic evaluation in stone-formers.
METHODS: 30 urinary stone-formers out of an initial 62 recruited provided a complete 24-hour urine and early morning spot urine samples for metabolic evaluation. Pearson correlation and Bland and Altman Test were used to assess the correlations and agreements.
RESULTS: Significant correlations were established between the 24-hour urinary solute excretions and the corresponding early morning spot urine solute/creatinine ratios for calcium, magnesium, urate, potassium, oxalate, citrate, and the Differential Gibb's free energy value of calcium oxalate DG(CaOx) values. However, all these solute/creatinine measurements between the 24-hour and early morning spot urine samples were judged to be not within the acceptable limits based on the estimated "limit of agreement" by the Bland and Altman Test of Agreement. Diurnal circadian rhythm and postprandial excretion surge are thought to be responsible for the disagreements.
CONCLUSIONS: Thus, the early morning spot urine is not suitable to be used interchangeably to replace the 24-hour urine collection in the evaluation of urinary metabolic abnormalities in stone-formers. A good correlation does not translate to an agreement between the 2 measurements.
Inorganic nanoparticles are commonly employed as vectors for delivering drugs into cancer cells while decreasing undesired cytotoxicity in healthy tissues. Carbonate apatite is an attractive nonviral vector that releases drugs at acidic environment inside the cells following endocytosis. However, maintaining the smaller particle size is crucial for enhancing cellular uptake of drugs as well as prolonging their systemic circulation time. We aimed to modify carbonate apatite with citrate for reducing the growth kinetics of carbonate apatite particles and enhancing the cellular uptake of cyclophosphamide via endocytosis. Several concentrations of sodium citrate were used to fabricate citrate-modified carbonate apatite (CMCA) particle complexes in absence or presence of cyclophosphamide. The binding affinity of the drug towards the particles and its cellular uptake were measured by high-performance liquid chromatography (HPLC). The nanoparticles' average size and zeta potential were determined by Malvern Zetasizer. Fourier-transform infrared spectroscopy (FTIR) was performed to justify association of citrate with carbonate apatite. MTT assay was performed to evaluate the cell viability. CMCA exhibited 6% more binding efficiency for cyclophosphamide and promoted fast cellular uptake of cyclophosphamide with enhanced cytotoxicity in MCF-7 cells, compared to unmodified carbonate apatite. Therefore, CMCA nanoparticles have a high potential for intracellular delivery of anti-cancer drugs and demand for further investigated in animal models of cancer.
Silver-reduced graphene oxide (Ag-rGO) nanohybrid was synthesized by applying a slight modification to the Turkevich method using trisodium citrate as a reducing and stabilizing agent to catalyze the non-enzymatic electrochemical detection of hydrogen peroxide (H₂O₂). Spherical silver nanoparticles (AgNPs) with an average particle size of 2.2 nm surfaced on reduced graphene oxide (rGO) sheets. Cyclic voltammograms (CV) obtained from glassy carbon (GC) electrode coated with Ag-rGO nanohybrid (4 mM) exhibited a peak at an overpotential of -0.52 V, with a larger faradaic current for the reduction of H₂O₂. Using the modified electrode for the linear sweep voltammetry (LSV) detection of H₂O₂, the detection limit and sensitivity were determined to be 4.8 μM (S/N ═ 3) and 0.0262 μA μM-1, respectively. The sensor appeared selective and stable towards H₂O₂ in the presence of possible interference, and it also demonstrated good recoveries of H₂O₂ concentration in real water samples.
The effectiveness of sodium citrate as a prophylaxis against acid aspiration syndrome was studied in 3 groups of obstetric patients. Group I was the control group which consisted of 20 patients in established labour who were not likely to require caesarean section. No antacid had been given to these patients. Group II consisted of 20 patients who underwent elective caesarean section, while Group III consisted of another 20 patients who underwent emergency caesarean section. Group II and III were given 30ml of 0.3M sodium citrate as soon as they arrived in the operation theatre. The gastric content was aspirated after the induction of anaesthesia and at the end of surgery just before extubation. The volume was measured and a sample sent for pH analysis. Sodium citrate was found to increase the gastric pH significantly in both Group II and III patients when compared with Group I patients who underwent emergency caesarean section. We conclude that 30ml of 0.3M sodium citrate is effective in increasing gastric pH though it tends to be associated with an increase in gastric volume.
The efficacy of a single oral dose of 0.3M of sodium citrate alone as a prophylaxis against acid aspiration syndrome in obstetric patients undergoing LSCS (elective and emergency) was compared with that of intravenous ranitidine. One group of patients was given 30 ml of 0.3M sodium citrate orally just before the induction of anaesthesia while the other group was given 50mg of ranitidine intravenously together with the 30ml of 0.3M sodium citrate. This was done for both the elective and the emergency groups of patients. There was no significant difference in the mean pH of the gastric aspirate obtained from those given sodium citrate alone and those given sodium citrate and ranitidine in either the elective or the emergency group. However, in the emergency group, those who were given sodium citrate alone tend to have a larger volume of gastric aspiration when compared with those given ranitidine together with the sodium citrate. There were significantly more patients with gastric aspirates of more than 25ml in the emergency group to which sodium citrate alone was given. It would appear that supplementing an intravenous dose of ranitidine with the oral dose of sodium citrate is useful in emergency LSCS as a prophylaxis against acid aspiration syndrome.
This study investigated the different thicknesses of TiO2 photoanode films and the effect of surface plasmon resonance (SPR) of Ag-TiO2 nanocomposites on the current-voltage (I-V) performance of dye-sensitized solar cells (DSSC). The TiO2 layer was deposited using the doctor blade technique and the thickness of the TiO2 films was controlled by using a different number of Scotch tape layers. The silver nanoparticles (AgNP) were synthesised using a chemical reduction method and the concentration of sodium citrate as a reducing agent was varied from 4 to 12 mM to study the effect of citrate ion on the size of the nanoparticles. Ag-TiO2 nanopowder was prepared by adding pure anatase TiO2 powder into AgNP colloidal solution. The mixture was left to dry for 24 h to obtain Ag-TiO2 powder for paste preparation. The three-layer Scotch tape, with thickness of 14.38 µm, achieved a high efficiency of 4.14%. This results showed that three layers was the optimal thickness to improve dye loading and to reduce the charge recombination rate. As for the Ag-TiO2 nanocomposites, 10 mM of AgNP, with a mean diameter of 65.23 nm and high efficiency of 6.92%, proved that SPR can enhance the absorption capability of dye and improve the photon-to-electron generation.
The concentration of homocysteine (Hcy) rises rapidly after the collection of blood. This feature requires blood to be collected into the anticoagulants EDTA or heparin and the plasma to then be immediately separated; alternatively, the blood may be kept on ice and centrifuged within 1 hour. The use of chemical preservatives has been proposed as a means of stabilising Hcy levels in whole blood after collection. The objective of this study was to determine whether the commonly available fluoride-oxalate (Fl-Ox) and sodium citrate (Na-Cit) containers could stabilise Hcy levels in blood. Our results showed that when blood was collected into potassium EDTA (K-EDTA) tubes, Hcy levels rose from initial levels, on standing at room temperature (approximately 25 degrees C), by an average of 21% after 3 hours and 32% after 5 hours. The initial Hcy levels of blood collected into Fl-Ox and Na-Cit containers, however, were lower, at averages of 89% and 91%, respectively, compared to that of the same samples when collected into K-EDTA tubes. Hcy in these samples subsequently rose on standing, and after 5 hours was, on the average, 10 and 13% higher, respectively, compared with the initial levels in K-EDTA tubes. We conclude that Fl-Ox and Na-Cit do not stabilise Hcy in blood after collection and should not be used as preservatives.
Two new garcinia acid derivatives, 2-(butoxycarbonylmethyl)-3-butoxycarbonyl-2-hydroxy-3-propanolide and 1',1"-dibutyl methyl hydroxycitrate, were isolated from the fruits of Garcinia atroviridis guided by TLC bioautography against the fungus Cladosporium herbarum. The structures of these compounds were established by spectral analysis. The former compound represents a unique beta-lactone structure and the latter compound is most likely an artefact of garcinia acid (= hydroxycitric acid). Both compounds showed selective antifungal activity comparable to that of cycloheximide (MID: 0.5 microg/spot) only against C herbarum at the MIDs of 0.4 and 0.8 microg/spot but were inactive against bacteria (Bacillus subtilis, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli), other fungi (Alternaria sp., Fusarium moniliforme and Aspergillus ochraceous) including the yeast Candida albicans.
The in vitro antitumour-promoting, cytotoxic, and antioxidant activities of two ester derivatives of garcinia acid, that is, 2-(butoxycarbonylmethyl)-3-butoxycarbonyl-2-hydroxy-3-propanolide (1) and 1',1''-dibutyl methyl hydroxycitrate (2), that had been previously isolated from the fruits of Garcinia atroviridis Griff. ex T. Anders (Guttiferae), were examined. Based on the inhibition of Epstein-Barr virus early antigen (EBV-EA) activation, compound 1 (IC(50): 70 μM) showed much higher (8-fold) antitumour-promoting activity than compound 2 (IC(50): 560 μM). In addition, both compounds were nontoxic towards CEM-SS (human T-lymphoblastic leukemia) cells (CD(50): >100 μM), Raji (human B-lymphoblastoid) cells (CD(50): >600 μM), and brine shrimp (LD(50): >300 μM). Although the antitumour-promoting activity of compound 1 is moderate compared with the known antitumour promoter genistein, its non-toxicity suggests the potential of compound 1 and related structures as chemopreventive agents. The weak antioxidant activity displayed by both compounds also suggested that the primary antitumour-promoting mechanism of compound 1 did not involve oxidative-stress quenching.
Low aqueous solubility is a major problem faced during formulation development of new drug molecules. Lurasidone HCl (LRD) is an antipsychotic agent specially used in the treatments of schizophrenia and is a good example of the problems associated with low aqueous solubility. Lurasidone is practically insoluble in water, has poor bioavailability and slow onset of action and therefore cannot be given in emergency clinical situations like schizophrenia. Hence, purpose of this research was to provide a fast dissolving oral dosage form of Lurasidone. This dosage form can provide quick onset of action by using the concept of mixed hydrotropy. Initially, solubility of LRD was determined individually in nicotinamide, sodium citrate, urea and sodium benzoate at concentration of 10, 20, 30 and 40% w/v solutions using purified water as a solvent. Highest solubility was obtained in 40% sodium benzoate solution. In order to decrease the individual hydrotrope concentration mixed hydrotropic agents were used. Highest solubility was obtained in 15:20:5 ratio of Nicotinamide + sodium benzoate + sodium citrate. This optimized combination was utilized in the preparation of solid dispersions by using distilled water as a solvent. Solid dispersions were evaluated for X-ray diffraction, differential scanning calorimetry and Fourier-transform infrared to show no drug-hydrotropes interaction has occurred. This solid dispersion was compressed to form fast dissolving tablets. Dissolution studies of prepared tablets were done using USP Type II apparatus. The batch L3 tablets show 88% cumulative drug release within 14 min and in vitro dispersion time was 32 min. It was concluded that the concept of mixed hydrotropic solid dispersion is novel, safe and cost-effective technique for enhancing the bioavailability of poorly water-soluble drugs. The miraculous enhancement in solubility and bioavailability of Lurasidone is clear indication of the potential of mixed hydrotropy to be used in future for other poorly water-soluble drugs in which low bioavailability is a major concern.
An aqueous two-phase flotation (ATPF) system based on polyethylene glycol (PEG) and sodium citrate (NaNO3C6H5O7·2H2O) was considered for primary recovery of bacteriocin-like inhibitory substance (BLIS) from Pediococcus acidilactici Kp10. The effects of ATPF parameters namely phase composition, tie-line length (TLL), volume ratio between the two phases (VR), amount of crude load (CL), pH, nitrogen gas flow rate (FR) and flotation time (FT) on the performance of recovery were evaluated. BLIS was mainly concentrated into the upper PEG-rich phase in all systems tested so far. The optimum conditions for BLIS purification, which composed of PEG 8000/sodium citrate, were: TLL of 42.6, VR of 0.4, CL of 22% (w/w), pH 7, average FT of 30min and FR of 20mL/min. BLIS was partially purified up to 5.9-fold with a separation efficiency of 99% under this optimal conditions. A maximum yield of BLIS activity of about 70.3% was recovered in the PEG phase. The BLIS from the top phase was successfully recovered with a single band in SDS-gel with molecular weight of about 10-15kDa. ATPF was found to be an effective technique for the recovery of BLIS from the fermentation broth of P. acidilactici Kp10.
Mild steel is the most common metal used in industry. However, mild steel easily corrodes when exposed to environment. One way to protect mild steel from corrodes is by coating it with more noble metal like copper and its alloys. In this study, copper and Cu-Ni alloys were successfully coated on the mild steel substrate by electrodeposition technique using alkaline citrate solutions containing Cu and Ni ions precursors. The reaction and mechanisms of the electrodeposition of copper and Cu-Ni alloys on the mild steel substrate were investigated by cyclic voltammetry and chronoamperometry methods. Surface morphology of the coatings was examined by FESEM. The elemental compositions of the coatings were confirmed by EDAX analysis. The molar ratios of Cu-Ni solutions have affected the formation of the coatings. Corrosion study shows that copper coated mild steel can improve the corrosion resistance of the mild steel in 0.5 M NaCl. Cu-Ni coating prepared from Cu60-Ni40 showed the highest corrosion resistance. The order of the corrosion resistance of the samples in 0.5 M NaCl at 25 oC is Cu60-Ni40> Cu75- Ni25> Cu90-Ni10> Cu100> mild steel.
The use of T1 lipase in automatic dishwashing detergent (ADD) is well established, but efficiency in hard water is very low. A new enzymatic environmentally-friendly dishwashing was formulated to be efficient in both soft and hard water. Thermostable enzymes such as T1 lipase from Geobacillus strain T1, Rand protease from Bacillussubtilis strain Rand, and Maltogenic amylase from Geobacillus sp. SK70 were produced and evaluated for an automatic dishwashing detergent formulation. The components of the new ADD were optimized for compatibility with these three enzymes. In compatibility tests of the enzymes with different components, several criteria were considered. The enzymes were mostly stable in non-ionic surfactants, especially polyhydric alcohols, Glucopon UP 600, and in a mixture of sodium carbonate and glycine (30:70) buffer at a pH of 9.25. Sodium polyacrylate and sodium citrate were used in the ADD formulation as a dispersing agent and a builder, respectively. Dishwashing performance of the formulated ADDs was evaluated in terms of percent of soil removed using the Leenert's Improved Detergency Tester. The results showed that the combination of different hydrolysis enzymes could improve the washing efficiency of formulated ADD compared to the commercial ADD "Finish" at 40 and 50 C.