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Hydroxyapatite nanoparticles: electrospinning and calcination of hydroxyapatite/polyvinyl butyral nanofibers and growth kinetics

Zakaria SM, Sharif Zein SH, Othman MR, Jansen JA

J Biomed Mater Res A, 2013 Jul;101(7):1977-85.
PMID: 23225849 DOI: 10.1002/jbm.a.34506

Electrospinning of hydroxyapatite (HA)/polyvinyl butyral solution resulted in the formation of fibers with average diameter of 937-1440 nm. These fibers were converted into HA nanoparticles with size <100 nm after undergoing calcination treatment at 600°C. The diameter of the fiber was found to be influenced by applied voltage and spinning distance. The injection flowrate did not affect the diameter significantly. The electrospinning method successfully reduced the commercial HA particle size in the range of 400-1100 nm into <100 nm. The dispersion of the finally calcined HA nanoparticles was improved significantly after anionic sodium dodecyl sulfate surfactant was introduced. The experimental data of HA growth kinetics were subjected to the integral method of analysis, and the rate law of the reaction was found to follow the first order reaction.

Matched MeSH terms: Indicators and Reagents
Electrochemical-assisted photodegradation of dye on TiO2 thin films: investigation on the effect of operational parameters

Zainal Z, Lee CY, Hussein MZ, Kassim A, Yusof NA

J Hazard Mater, 2005 Feb 14;118(1-3):197-203.
PMID: 15721544

Electrochemical-assisted photodegradation of methyl orange has been investigated using TiO2 thin films. The films were prepared by sol-gel dip-coating method. Several operational parameters to achieve optimum efficiency of this electrochemical-assisted photodegradation system have been tested. Photoelectrochemical degradation was studied using different light sources and light intensity. The light sources chosen ranged from ultraviolet to visible light. The effect of agitation of the solution at different speeds has also been studied. Slight improvement of photodegradation rate was observed by applying higher agitation speed. Investigation on the electrode after repeated usages show the electrode can be reused up to 20 times with percentage of deficiency less than 15%. The study on the effect of solution temperature indicated that the activation energy of the methyl orange degradation is 18.63 kJ mol(-1).

Matched MeSH terms: Indicators and Reagents/chemistry*
Fulltext Differentiation of dental pulp stem cells into neuron-like cells in serum-free medium

Zainal Ariffin SH, Kermani S, Zainol Abidin IZ, Megat Abdul Wahab R, Yamamoto Z, Senafi S, et al.

Stem Cells Int, 2013;2013:250740.
PMID: 24348580 DOI: 10.1155/2013/250740

Dental pulp tissue contains dental pulp stem cells (DPSCs). Dental pulp cells (also known as dental pulp-derived mesenchymal stem cells) are capable of differentiating into multilineage cells including neuron-like cells. The aim of this study was to examine the capability of DPSCs to differentiate into neuron-like cells without using any reagents or growth factors. DPSCs were isolated from teeth extracted from 6- to 8-week-old mice and maintained in complete medium. The cells from the fourth passage were induced to differentiate by culturing in medium without serum or growth factors. RT-PCR molecular analysis showed characteristics of Cd146(+) , Cd166(+) , and Cd31(-) in DPSCs, indicating that these cells are mesenchymal stem cells rather than hematopoietic stem cells. After 5 days of neuronal differentiation, the cells showed neuron-like morphological changes and expressed MAP2 protein. The activation of Nestin was observed at low level prior to differentiation and increased after 5 days of culture in differentiation medium, whereas Tub3 was activated only after 5 days of neuronal differentiation. The proliferation of the differentiated cells decreased in comparison to that of the control cells. Dental pulp stem cells are induced to differentiate into neuron-like cells when cultured in serum- and growth factor-free medium.

Matched MeSH terms: Indicators and Reagents
Restoration of engraved marks on steel surfaces by etching technique

Zaili MA, Kuppuswamy R, Harun H

Forensic Sci Int, 2007 Aug 24;171(1):27-32.
PMID: 17088038

It is known that restoration of erased engraved identification marks on the engine and the chassis of a car or on a firearm has low success rate. Unlike stamping, engraving on a metal surface leaves no pronounced, permanent subsurface deformation in the crystalline structure, also called dislocation that can be revealed by suitable methods. Hence, the current research work investigated whether metallographic reagents used in the restoration of stamp (compression) marks could be applied to recover engraved marks on steel surfaces and also to establish the sensitivity and effectiveness of some of these reagents for the restoration of the marks. Experiments were conducted by mechanically engraving alphanumeric characters on several steel plates using a computer controlled engraving machine called Gravograph. The markings were later erased from the above steel plates by removing the metal in stages of 0.01 mm through 0.04 mm below the bottom of the engraving. Several plates were thus prepared wherein each one had been abraded to a specific depth. Then eight metallographic reagents were tested on each one of the above erased plates using a swabbing technique. The results had shown that while most of the reagents were able to restore marks up to certain levels of erasure, the reagent 5 g copper sulphate, 60 ml water, 30 ml concentrated ammonium hydroxide and 60 ml concentrated hydrochloric acid restored marks erased to a depth of 0.04 mm below the engraving depth, thus presenting itself the most sensitive reagent. Quite significantly, the above reagent was also able to decipher successfully the original engraved marks that had been erased and engraved with a new number, or obliterated by centre punching. The results of this research work should benefit the forensic practitioners engaged in the serial number recovery on vehicles, firearms and other objects.

Matched MeSH terms: Indicators and Reagents
Fulltext Arene diazonium saccharin intermediates: a greener and cost-effective alternative method for the preparation of aryl iodide

Zaharani L, Ghaffari Khaligh N, Shahnavaz Z, Rafie Johan M

Turk J Chem, 2020;44(3):535-542.
PMID: 33488175 DOI: 10.3906/kim-2002-26

In the current protocol, the arene diazonium saccharin derivatives were initially produced from various substituted aromatic amines; subsequently, these intermediates were treated with a greener organic iodide for the preparation of the aryl iodide. We tried to choose low-cost, commercially available, biodegradable, recoverable, ecofriendly, and safe reagents and solvents. The arene diazonium saccharin intermediates could be stored in the liquid phase into a refrigerator for a long time with no significant loss activity. The outstanding merits of the current protocol (a) included the partial recovering of saccharin and tetraethylammonium salt, (b) reduce the use of solvents and the reaction steps due to eliminating separation and purification of intermediates, (c) good yield of the sterically hindered substrates, and (d) avoid the generation of heavy metal or corrosive waste.

Matched MeSH terms: Indicators and Reagents
Enzymatic electrochemical detection of epidemic-causing Vibrio cholerae with a disposable oligonucleotide-modified screen-printed bisensor coupled to a dry-reagent-based nucleic acid amplification assay

Yu CY, Ang GY, Chan KG, Banga Singh KK, Chan YY

Biosens Bioelectron, 2015 Aug 15;70:282-8.
PMID: 25835520 DOI: 10.1016/j.bios.2015.03.048

In this study, we developed a nucleic acid-sensing platform in which a simple, dry-reagent-based nucleic acid amplification assay is combined with a portable multiplex electrochemical genosensor. Preparation of an amplification reaction mix targeting multiple DNA regions of interest is greatly simplified because the lyophilized reagents need only be reconstituted with ultrapure water before the DNA sample is added. The presence of single or multiple target DNAs causes the corresponding single-stranded DNA (ssDNA) amplicons to be generated and tagged with a fluorescein label. The fluorescein-labeled ssDNA amplicons are then analyzed using capture probe-modified screen-printed gold electrode bisensors. Enzymatic amplification of the hybridization event is achieved through the catalytic production of electroactive α-naphthol by anti-fluorescein-conjugated alkaline phosphatase. The applicability of this platform as a diagnostic tool is demonstrated with the detection of toxigenic Vibrio cholerae serogroups O1 and O139, which are associated with cholera epidemics and pandemics. The platform showed excellent diagnostic sensitivity and specificity (100%) when challenged with 168 spiked stool samples. The limit of detection was low (10 colony-forming units/ml) for both toxigenic V. cholerae serogroups. A heat stability assay revealed that the dry-reagent amplification reaction mix was stable at temperatures of 4-56 °C, with an estimated shelf life of seven months. The findings of this study highlight the potential of combining a dry-reagent-based nucleic acid amplification assay with an electrochemical genosensor in a more convenient, sensitive, and sequence-specific detection strategy for multiple target nucleic acids.

Matched MeSH terms: Indicators and Reagents
On the sensitivity of some common metallographic reagents to restoring obliterated marks on medium carbon (0.31% C) steel surfaces

Yin SH, Kuppuswamy R

Forensic Sci Int, 2009 Jan 10;183(1-3):50-3.
PMID: 19041202 DOI: 10.1016/j.forsciint.2008.10.009

Chemical etching, which is the most sensitive method to recover obliterated serial numbers on metal surfaces, has been practised quite successfully in forensic science laboratories all over the world. A large number of etchants suitable for particular metal surfaces based on empirical studies is available in the literature. This article reviews the sensitivity and efficacy of some popular etchants for recovering obliterated marks on medium carbon steel (0.31% C with ferrite-pearlite microstructure) used in automobile parts. The experiments involved engraving these carbon steel plates with some alphanumeric characters using a computer controlled machine "Gravograph" and erasing them to several depths below the bottom of their engraving depth. Seven metallographic reagents of which most of them were copper containing compounds were chosen for etching. The erased plates were etched with every one of these etchants using swabbing method. The results have revealed that Fry's reagent comprising cupric chloride 90 g, hydrochloric acid 120 mL and water 100mL provided the necessary contrast and was concluded to be the most sensitive. The same reagent was recommended by earlier workers for revealing strain lines in steel surfaces. Earlier, another reagent containing 5 g copper sulphate, 60 mL water, 30 mL (conc.) ammonium hydroxide, and 60 mL (conc.) hydrochloric acid was proved to be more sensitive to restore erased marks on low carbon steel (0.1% C with ferrite-pearlite structure) [M.A.M. Zaili, R. Kuppuswamy, H. Harun, Restoration of engraved marks on steel surfaces by etching technique, Forensic Sci. Int. 171 (2007) 27-32]. Thus the sensitivity of the etching reagent on steel surfaces appeared to be dependent on the content of carbon in the steel.

Matched MeSH terms: Indicators and Reagents
A survey of some metallographic etching reagents for restoration of obliterated engraved marks on aluminium-silicon alloy surfaces

Uli N, Kuppuswamy R, Amran MF

Forensic Sci Int, 2011 May 20;208(1-3):66-73.
PMID: 21145675 DOI: 10.1016/j.forsciint.2010.11.005

A brief survey to assess the sensitivity and efficacy of some common etching reagents for revealing obliterated engraved marks on Al-Si alloy surfaces is presented. Experimental observations have recommended use of alternate swabbing of 10% NaOH and 10% HNO(3) on the obliterated surfaces for obtaining the desired results. The NaOH etchant responsible for bringing back the original marks resulted in the deposition of some dark coating that has masked the recovered marks. The coating had been well removed by dissolving it in HNO(3) containing 10-20% acid. However, the above etching procedure was not effective on aluminium (99% purity) and Al-Zn-Mg-Cu alloy surfaces. Also the two reagents (i) immersion in 10% aq. phosphoric acid and (ii) alternate swabbing of 60% HCl and 40% NaOH suggested earlier for high strength Al-Zn-Mg-Cu alloys [23] were quite ineffective on Al-Si alloys. Thus different aluminium alloys needed different etching treatments for successfully restoring the obliterated marks. Al-Si alloys used in casting find wide applications especially in the manufacture of engine blocks of motor vehicles. Hence, the results presented in this paper are of much relevance in serial number restoration problems involving this alloy.

Matched MeSH terms: Indicators and Reagents
Evaluation of filter paper eluates for seroepidemiological studies on malaria in peninsular Malaysia

Thomas V, Chan WC

Trop Geogr Med, 1982 Jun;34(2):145-9.
PMID: 6750883
Matched MeSH terms: Indicators and Reagents*
Application of the artificial neural network in quantitative structure-gradient elution retention relationship of phenylthiocarbamyl amino acids derivatives

Tham SY, Agatonovic-Kustrin S

J Pharm Biomed Anal, 2002 May 15;28(3-4):581-90.
PMID: 12008137

Quantitative structure-retention relationship(QSRR) method was used to model reversed-phase high-performance liquid chromatography (RP-HPLC) separation of 18 selected amino acids. Retention data for phenylthiocarbamyl (PTC) amino acids derivatives were obtained using gradient elution on ODS column with mobile phase of varying acetonitrile, acetate buffer and containing 0.5 ml/l of triethylamine (TEA). Molecular structure of each amino acid was encoded with 36 calculated molecular descriptors. The correlation between the molecular descriptors and the retention time of the compounds in the calibration set was established using the genetic neural network method. A genetic algorithm (GA) was used to select important molecular descriptors and supervised artificial neural network (ANN) was used to correlate mobile phase composition and selected descriptors with the experimentally derived retention times. Retention time values were used as the network's output and calculated molecular descriptors and mobile phase composition as the inputs. The best model with five input descriptors was chosen, and the significance of the selected descriptors for amino acid separation was examined. Results confirmed the dominant role of the organic modifier in such chromatographic systems in addition to lipophilicity (log P) and molecular size and shape (topological indices) of investigated solutes.

Matched MeSH terms: Indicators and Reagents
Fulltext Determination of ammonium ion using a reagentless amperometric biosensor based on immobilized alanine dehydrogenase

Tan LL, Musa A, Lee YH

Sensors (Basel), 2011;11(10):9344-60.
PMID: 22163699 DOI: 10.3390/s111009344

The use of the enzyme alanine dehydrogenase (AlaDH) for the determination of ammonium ion (NH(4)(+)) usually requires the addition of pyruvate substrate and reduced nicotinamide adenine dinucleotide (NADH) simultaneously to effect the reaction. This addition of reagents is inconvenient when an enzyme biosensor based on AlaDH is used. To resolve the problem, a novel reagentless amperometric biosensor using a stacked methacrylic membrane system coated onto a screen-printed carbon paste electrode (SPE) for NH(4)(+) ion determination is described. A mixture of pyruvate and NADH was immobilized in low molecular weight poly(2-hydroxyethyl methacrylate) (pHEMA) membrane, which was then deposited over a photocured pHEMA membrane (photoHEMA) containing alanine dehydrogenase (AlaDH) enzyme. Due to the enzymatic reaction of AlaDH and the pyruvate substrate, NH(4)(+) was consumed in the process and thus the signal from the electrocatalytic oxidation of NADH at an applied potential of +0.55 V was proportional to the NH(4)(+) ion concentration under optimal conditions. The stacked methacrylate membranes responded rapidly and linearly to changes in NH(4)(+) ion concentrations between 10-100 mM, with a detection limit of 0.18 mM NH(4)(+) ion. The reproducibility of the amperometrical NH(4)(+) biosensor yielded low relative standard deviations between 1.4-4.9%. The stacked membrane biosensor has been successfully applied to the determination of NH(4)(+) ion in spiked river water samples without pretreatment. A good correlation was found between the analytical results for NH(4)(+) obtained from the biosensor and the Nessler spectrophotometric method.

Matched MeSH terms: Indicators and Reagents
Comparison of solvent extraction and solid-phase extraction for the determination of organochlorine pesticide residues in water

Tan GH

Analyst, 1992 Jul;117(7):1129-32.
PMID: 1524230

Solid-phase extraction (SPE) of organochlorine pesticide residues from environmental water samples was evaluated using octadecyl (C18)-bonded porous silica. The efficiency of SPE of these pesticide residues from reagent water samples at 1-5 micrograms dm-3 levels was compared with those obtained by solvent extraction with hexane and Freon TF (trichlorotrifluoroethane). Average recoveries exceeding 80% for these organochlorine pesticides were obtained via the SPE method using small cartridges containing 100 mg of 40 microns C18-bonded porous silica. The average recovery by solvent extraction with hexane and Freon TF exceeded 90% in both instances. It was concluded that the recoveries and precision for the SPE of organochlorine pesticides were poorer than those for the solvent extraction method. Organochlorine pesticide residue levels in environmental water samples from two major rivers flowing through predominantly rice-growing areas were monitored by gas chromatography using the solvent extraction method with hexane. Exceptionally high levels of organochlorine pesticide residues such as BHC, DDT, heptachlor, endosulfan and dieldrin were found in these water samples.

Matched MeSH terms: Indicators and Reagents
Fulltext cNTnC and fYTnC2, Genetically Encoded Green Calcium Indicators Based on Troponin C from Fast Animals

Subach OM, Vlaskina AV, Agapova YK, Korzhenevskiy DA, Nikolaeva AY, Varizhuk AM, et al.

Int J Mol Sci, 2022 Nov 23;23(23).
PMID: 36498942 DOI: 10.3390/ijms232314614

NTnC-like green fluorescent genetically encoded calcium indicators (GECIs) with two calcium ion binding sites were constructed using the insertion of truncated troponin C (TnC) from Opsanus tau into green fluorescent proteins (GFPs). These GECIs are small proteins containing the N- and C-termini of GFP; they exert a limited effect on the cellular free calcium ion concentration; and in contrast to calmodulin-based calcium indicators they lack undesired interactions with intracellular proteins in neurons. The available TnC-based NTnC or YTnC GECIs had either an inverted response and high brightness but a limited dynamic range or a positive response and fast kinetics in neurons but lower brightness and an enhanced but still limited dF/F dynamic range. Here, we solved the crystal structure of NTnC at 2.5 Å resolution. Based on this structure, we developed positive NTnC2 and inverted iNTnC2 GECIs with a large dF/F dynamic range in vitro but very slow rise and decay kinetics in neurons. To overcome their slow responsiveness, we swapped TnC from O. tau in NTnC2 with truncated troponin C proteins from the muscles of fast animals, namely, the falcon, hummingbird, cheetah, bat, rattlesnake, and ant, and then optimized the resulting constructs using directed molecular evolution. Characterization of the engineered variants using purified proteins, mammalian cells, and neuronal cultures revealed cNTnC GECI with truncated TnC from Calypte anna (hummingbird) to have the largest dF/F fluorescence response and fast dissociation kinetics in neuronal cultures. In addition, based on the insertion of truncated TnCs from fast animals into YTnC2, we developed fYTnC2 GECI with TnC from Falco peregrinus (falcon). The purified proteins cNTnC and fYTnC2 had 8- and 6-fold higher molecular brightness and 7- and 6-fold larger dF/F responses to the increase in Ca2+ ion concentration than YTnC, respectively. cNTnC GECI was also 4-fold more photostable than YTnC and fYTnC2 GECIs. Finally, we assessed the developed GECIs in primary mouse neuronal cultures stimulated with an external electric field; in these conditions, cNTnC had a 2.4-fold higher dF/F fluorescence response than YTnC and fYTnC2 and was the same or slightly slower (1.4-fold) than fYTnC2 and YTnC in the rise and decay half-times, respectively.

Matched MeSH terms: Indicators and Reagents
Fulltext Evaluation of female Aedes aegypti proteome via LC-ESI-MS/MS using two protein extraction methods

Shettima A, Ishak IH, Abdul Rais SH, Abu Hasan H, Othman N

PeerJ, 2021;9:e10863.
PMID: 33717682 DOI: 10.7717/peerj.10863

Background: Proteomic analyses have broadened the horizons of vector control measures by identifying proteins associated with different biological and physiological processes and give further insight into the mosquitoes' biology, mechanism of insecticide resistance and pathogens-mosquitoes interaction. Female Ae. aegypti ingests human blood to acquire the requisite nutrients to make eggs. During blood ingestion, female mosquitoes transmit different pathogens. Therefore, this study aimed to determine the best protein extraction method for mass spectrometry analysis which will allow a better proteome profiling for female mosquitoes.
Methods: In this present study, two protein extractions methods were performed to analyze female Ae. aegyti proteome, via TCA acetone precipitation extraction method and a commercial protein extraction reagent CytoBusterTM. Then, protein identification was performed by LC-ESI-MS/MS and followed by functional protein annotation analysis.
Results: The CytoBusterTM reagent gave the highest protein yield with a mean of 475.90 µg compared to TCA acetone precipitation extraction showed 283.15 µg mean of protein. LC-ESI-MS/MS identified 1,290 and 890 proteins from the CytoBusterTM reagent and TCA acetone precipitation, respectively. When comparing the protein class categories in both methods, there were three additional categories for proteins identified using CytoBusterTM reagent. The proteins were related to scaffold/adaptor protein (PC00226), protein binding activity modulator (PC00095) and intercellular signal molecule (PC00207). In conclusion, the CytoBusterTM protein extraction reagent showed a better performance for the extraction of proteins in term of the protein yield, proteome coverage and extraction speed.

Matched MeSH terms: Indicators and Reagents
A Green Alternative for Aryl Iodide Preparation from Aromatic Amines

Shahnavaz Z, Zaharani L, Johan MR, Khaligh NG

Curr Org Synth, 2020;17(2):131-135.
PMID: 32013833 DOI: 10.2174/1570179417666200203121437

BACKGROUND: In continuation of our previous work and the applications of saccharin, we encouraged to investigate the one-pot synthesis of the aryl iodides by the diazotization of the arene diazonium saccharin salts.
OBJECTIVE: Arene diazonium salts play an important role in organic synthesis as intermediate and a wide variety of aromatic compounds have been prepared using them. A serious drawback of arene diazonium salts is their instability in a dry state; therefore, they must be stored and handled carefully to avoid spontaneous explosion and other hazard events.
METHODS: The arene diazonium saccharin salts were prepared as active intermediates in situ through the reaction of various aryl amines with tert-butyl nitrite (TBN) in the presence of saccharin (Sac-H). Then, in situ obtained intermediates were used into the diazotization step without separation and purification in the current protocol.
RESULTS: A variety of aryl iodides were synthesized at a greener and low-cost method in the presence of TBN, Sac-H, glacial acetic acid, and TEAI.
CONCLUSION: In summary, a telescopic reaction is developed for the synthesis of aryl iodides. The current methodology is safe, cost-effective, broad substrate scope, and metal-free. All used reagents are commercially available and inert to moisture and air. Also, the saccharine and tetraethylammonium cation could be partially recovered from the reaction residue, which reduces waste generation, energy consumption, raw material, and waste disposal costs.

Matched MeSH terms: Indicators and Reagents
Fulltext Accelerated nucleophilic substitution reactions of dansyl chloride with aniline under ambient conditions via dual-tip reactive paper spray

Sarih NM, Romero-Perez D, Bastani B, Rauytanapanit M, Boisdon C, Praneenararat T, et al.

Sci Rep, 2020 12 09;10(1):21504.
PMID: 33299034 DOI: 10.1038/s41598-020-78133-4

Paper spray ionization (PSI) mass spectrometry (MS) is an emerging tool for ambient reaction monitoring via microdroplet reaction acceleration. PSI-MS was used to accelerate and monitor the time course of the reaction of dansyl chloride with aniline, in acetonitrile, to produce dansyl aniline. Three distinct PSI arrangements were explored in this study representing alternative approaches for sample loading and interaction; conventional single tip as well as two novel setups, a dual-tip and a co-axial arrangement were designed so as to limit any on-paper interaction between reagents. The effect on product abundance was investigated using these different paper configurations as it relates to the time course and distance of microdroplet travel. It was observed that product yield increases at a given distance and then decreases thereafter for all PSI configurations. The fluorescent property of the product (dansyl aniline) was used to visually inspect the reaction progress on the paper substrate during the spraying process. Amongst the variety of sample loading methods the novel dual-tip arrangement showed an increased product yield and microdroplet density, whilst avoiding any on-paper interaction between the reagents.

Matched MeSH terms: Indicators and Reagents
Comparison of signal-to-noise, blank determination, and linear regression methods for the estimation of detection and quantification limits for volatile organic compounds by gas chromatography

Sanagi MM, Ling SL, Nasir Z, Hermawan D, Ibrahim WA, Abu Naim A

J AOAC Int, 2010 2 20;92(6):1833-8.
PMID: 20166602

LOD and LOQ are two important performance characteristics in method validation. This work compares three methods based on the International Conference on Harmonization and EURACHEM guidelines, namely, signal-to-noise, blank determination, and linear regression, to estimate the LOD and LOQ for volatile organic compounds (VOCs) by experimental methodology using GC. Five VOCs, toluene, ethylbenzene, isopropylbenzene, n-propylbenzene, and styrene, were chosen for the experimental study. The results indicated that the estimated LODs and LOQs were not equivalent and could vary by a factor of 5 to 6 for the different methods. It is, therefore, essential to have a clearly described procedure for estimating the LOD and LOQ during method validation to allow interlaboratory comparisons.

Matched MeSH terms: Indicators and Reagents
Superior photoelectrocatalytic performance of ternary structural BiVO4/GQD/g-C3N4 heterojunction

Samsudin MFR, Ullah H, Tahir AA, Li X, Ng YH, Sufian S

J Colloid Interface Sci, 2021 Mar 15;586:785-796.
PMID: 33198982 DOI: 10.1016/j.jcis.2020.11.003

Herein, we performed an encyclopedic analysis on the photoelectrocatalytic hydrogen production of BiVO4/g-C3N4 decorated with reduced graphene oxide (RGO) or graphene quantum dots (GQDs). The differences between RGO and GQDs as an electron mediator was revealed for the first time in the perspective of theoretical DFT analysis and experimental validation. It was found that the incorporation of GQDs as an electron mediator promotes better photoelectrocatalytic hydrogen performance in comparison to the RGO. The addition of GQD can significantly improve the activity by 25.2 and 75.7% in comparison to the BiVO4/RGO/g-C3N4 and binary composite samples, respectively. Correspondingly, the BiVO4/GQD/g-C3N4 attained the highest photocurrent density of 19.2 mA/cm2 with an ABPE of 0.57% without the presence of any sacrificial reagents. This enhancement is stemming from the low photocharge carrier transfer resistance which was further verified via DFT study. The DFT analysis revealed that the BiVO4/GQD/g-C3N4 sample shared their electronic cloud density through orbital hybridization while the BiVO4/RGO/g-C3N4 sample show less mutual sharing. Additionally, the charge redistribution of the GQDs-composite at the heterostructure interface articulates a more stable and stronger heterojunction than the RGO-composite. Notably, this study provides new insights on the effect of different carbonaceous materials (RGO and GQDs) which are often used as an electron mediator to enhance photocatalytic activity.

Matched MeSH terms: Indicators and Reagents
Chemical compositions, antioxidant and antimicrobial activity of the essential oils of Piper officinarum (Piperaceae)

Salleh WM, Ahmad F, Yen KH, Sirat HM

Nat Prod Commun, 2012 Dec;7(12):1659-62.
PMID: 23413576

This study was designed to investigate the antioxidant and antimicrobial activities of the essential oils from Piper officinarum C. DC. GC and GC/MS analysis of the leaf and stem oils showed forty one components, representing 85.6% and 93.0% of the oil, respectively. The most abundant components in the leaf oil were beta-caryophyllene (11.2%), alpha-pinene (9.3%), sabinene (7.6%), beta-selinene (5.3%) and limonene (4.6%), while beta-caryophyllene (10.9%), alpha-phellandrene (9.3%), linalool (6.9%), limonene (6.7%) and alpha-pinene (5.0%) were the main components of the stem oil. The antioxidant activities were determined by using complementary tests: namely beta-carotene-linoleic acid, DPPH radical scavenging and total phenolic assays. The stems oil showed weak activity (IC50 = 777.4 microg/mL) in the DPPH system, but showed moderate lipid peroxidation inhibition in the beta-carotene-linoleic acid system (88.9 +/- 0.35%) compared with BHT (95.5 +/- 0.30%). Both oils showed weak activity against P. aeruginosa and E. coli with M IC values of 250 microg/mL.

Matched MeSH terms: Indicators and Reagents
Solvent extraction of lanthanum(III), europium(III) and lutetium(III) with fluorinated 1-phenyl-3-methyl-4-benzoyl-5-pyrazolones into chloroform

Saleh MI, Ahmad M, Darus H

Talanta, 1990 Jul;37(7):757-9.
PMID: 18965016

A series of chelating reagents, 1-phenyl-3-methyl-4-(2-fluorobenzoyl)-5-pyrazolone, 1-phenyl-3-methyl-4-(3-fluorobenzoyl)-5-pyrazolone and 1-phenyl-3-methyl-4-(4-fluorobenzoyl)-5-pyrazolone, has been synthesized. The extraction of Ln(III), (Ln = La, Eu and Lu) into chloroform with these reagents at 30 +/- 1 degrees has been studied. The composition of the complexes extracted has been determined by the slope method, and the extraction constants K(ex), were measured. The presence of the fluorine atom in the reagents does not make the K(ex), values much different from those obtained with the parent pyrazolone.

Matched MeSH terms: Indicators and Reagents

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