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  1. Linear chains in polymeric dicyclohexylammonium tributyl(4-oxo-4H-pyran-2,6-dicarboxylato)stannate and methylphenylammonium tributyl(pyridine-2,6-dicarboxylato)stannate containing trigonal bipyramidal tin
    Ng SW, Shanmuga Sundara Raj S, Fun HK, Razak IA, Hook JM
    Acta Crystallogr C, 2000 Aug;56 ( Pt 8):966-8.
    PMID: 10944291
    catena-Poly[dicyclohexylammonium [tributyltin-mu-(4-oxo-4H-pyran-2,6-dicarboxylato-O(2):O( 6))]], (C(12)H(24)N)[Sn(C(7)H(2)O(6))(C(4)H(9))(3)], consists of 4-oxo-4H-pyran-2,6-dicarboxylato groups that axially link adjacent tributyltin units into a linear polyanionic chain. The ammonium counter-ions surround the chain, and each cation forms a pair of hydrogen bonds to the double-bond carbonyl O atoms of the same dianionic group. The chain propagates in a zigzag manner along the c axis of the monoclinic cell. In catena-poly[methyl(phenyl)ammonium [tributyltin-mu-(pyridine-2,6-dicarboxylato-O(2):O(6))]], (C(7)H(10)N)[Sn(C(7)H(3)NO(4))(C(4)H(9))(3)], the pyridine-2, 6-dicarboxylato groups also link the tributyltin groups into a chain, but the hydrogen-bonded chain propagates linearly on the ac face of the monoclinic cell.
    Matched MeSH terms: Organotin Compounds/chemistry*; Polyesters/chemistry*
  2. Recent advances in thermal properties of hybrid cellulosic fiber reinforced polymer composites
    Krishnasamy S, Thiagamani SMK, Muthu Kumar C, Nagarajan R, R M S, Siengchin S, et al.
    Int J Biol Macromol, 2019 Dec 01;141:1-13.
    PMID: 31472211 DOI: 10.1016/j.ijbiomac.2019.08.231
    Bio-composites are easy to manufacture and environmentally friendly, could reduce the overall cost and provide lightweight due to the low density of the natural fibers. In a bid to compete with the synthetic fiber reinforced composites, a single natural fiber composite may not be a good choice to obtain optimal properties. Hence, hybrid composites are produced by adding two or more natural fibers together to obtain improved properties, such as mechanical, physical, thermal, water absorption, acoustic and dynamic, among others. Regarding thermal stability, the composites showed a significant change by varying the individual fiber compositions, fiber surface treatments, addition of fillers and coupling agents. The glass transition temperature and melting point obtained from the thermomechanical analysis and differential scanning calorimetry are not the same values for several hybrid composites, since the volume variation was not always parallel with the enthalpy change. However, the difference between the temperature calculated from the thermomechanical analysis and differential scanning calorimetry was lower. Significantly, this critical reviewed study has a potential of guiding all composite designers, manufacturers and users on right selection of composite materials for thermal applications, such as engine components (covers), heat shields and brake ducts, among others.
    Matched MeSH terms: Cellulose/chemistry*; Glass/chemistry*
  3. Environmental significance and geochemical speciation of trace elements in Lower Baram River sediments
    Prabakaran K, Nagarajan R, Eswaramoorthi S, Anandkumar A, Franco FM
    Chemosphere, 2019 Mar;219:933-953.
    PMID: 30572242 DOI: 10.1016/j.chemosphere.2018.11.158
    The geochemistry and distribution of major, trace and rare earth elements (REE's) was studied in the surface sediments of the Lower Baram River during two seasons: the Monsoon (MON) and Post - monsoon (POM). The major geochemical processes controlling the distribution and mobility of major, trace and REE's in the Lower Baram River surface sediments was revealed through factor analysis. The risk assessment of major and trace element levels was studied at three specific levels; i.e. the enrichment level [Contamination Factor (Cf), with the geo-accumulation index (Igeo)], the availability level [metals bound to different fractions, risk assessment code (RAC)], and the biological toxicity level [effect range low (ERL) and effect range medium (ERM)]. The results of all the indices indicate that Cu is the element of concern in the Lower Baram River sediments. The geochemical fractionation of major and trace elements were studied through sequential extraction and the results indicated a higher concentration of Mn in the exchangeable fraction. The element of concern, Cu, was found to be highly associated in the organic bound (F4) fraction during both seasons and a change in the redox, possibly due to storms or dredging activities may stimulate the release of Cu into the overlying waters of the Lower Baram River.
    Matched MeSH terms: Trace Elements/chemistry*; Geologic Sediments/chemistry*
  4. Preparation and characterization of imprinted zeolite-Y for p-cresol removal in haemodialysis
    Raharjo Y, Ismail AF, Othman MHD, Malek NANN, Santoso D
    Mater Sci Eng C Mater Biol Appl, 2019 Oct;103:109722.
    PMID: 31349515 DOI: 10.1016/j.msec.2019.05.007
    In this work, the novel imprinted zeolite (IZ) was synthesized, and its properties and performance in terms of adsorption of p-Cresol, which represent the protein-bounded uremic toxins in aqueous phase under phosphate buffer saline, were studied and compared with the synthesized zeolite-Y (ZeoY-S) and commercial CBV 100 zeolite-Y (ZeoY-C). The ZeoY-S was synthesized from sodium aluminate, NaOH, H2O and SiO2 under aging for 24 h at room temperature and hydrothermal condition for 24 h at 100 °C, with an initial composition of 10SiO2:Al2O3:4Na2O:180H2O. The ZeoY-S has been modified by using the imprinting technology to produce the IZ via the use of p-Cresol as a template. The p-Cresol successfully imprinted on the zeolite-Y was proved through the multipoint Brunauer-Emmett-Teller (BET) and the performance of IZ that was compared to ZeoY-S and ZeoY-C. Based on the BET results, it proves that the pore size of IZ is in accordance with the target compound, which is p-Cresol at 0.79 nm. This modification was able to adsorb p-Cresol 2.5 and 3.5 times higher than ZeoY-S and ZeoY-C can, respectively. Langmuir and Freundlich adsorption isotherm models, together with the pseudo-first and -second order and intra-particle diffusion kinetics models, were used to investigate the adsorption behavior of p-Cresol on the zeolites. The IZ has 4.30 times greater competitive molecules than ZeoY-S and the properties of IZ were not influenced by the content of other phenolic group uremic toxins as competitive molecules. It can be concluded that the micropores of zeolite as adsorbent can be modified using the imprinting technology in order to increase its sensitivity and selectivity towards p-Cresol.
    Matched MeSH terms: Cresols/chemistry*; Zeolites/chemistry*
  5. Fulltext Synthesis, characterization and advanced sustainable applications of titanium dioxide nanoparticles: A review
    Irshad MA, Nawaz R, Rehman MZU, Adrees M, Rizwan M, Ali S, et al.
    Ecotoxicol Environ Saf, 2021 Apr 01;212:111978.
    PMID: 33561774 DOI: 10.1016/j.ecoenv.2021.111978
    Nanotechnology is capturing great interest worldwide due to their stirring applications in various fields. Among nanoparticles (NPs), titanium dioxide (TiO2) NPs have been widely used in daily life and can be synthesized through various physical, chemical, and green methods. Green synthesis is a non-toxic, cost-effective, and eco-friendly route for the synthesis of NPs. Plenty of work has been reported on the green, chemical, physical and biological synthesis of TiO2 NPs and these NPs can be characterized through high tech. instruments. In the present review, dense data have been presented on the comparative synthesis of TiO2 NPs with different characteristics and their wide range of applications. Among the TiO2 NPs synthesis techniques, the green methods have been proven to be efficient than chemical synthesis methods because of the less use of precursors, time-effectiveness, and energy-efficiency during the green synthesis procedures. Moreover, this review describes the types of plants (shrubs, herbs and trees), microorganisms (bacteria, fungi and algae), biological derivatives (proteins, peptides, and starches) employed for the synthesis of TiO2 NPs. The TiO2 NPs can be effectively used for the treatment of polluted water and positively affected the plant physiology especially under abiotic stresses but the response varied with types, size, shapes, doses, duration of exposure, metal species along with other factors. This review also highlights the regulating features and future standpoints for the measurable enrichment in TiO2 NPs product and perspectives of TiO2 NPs reliable application.
    Matched MeSH terms: Plants/chemistry; Metal Nanoparticles/chemistry
  6. Cytotoxic xanthones from Garcinia penangiana Pierre
    Jabit ML, Khalid R, Abas F, Shaari K, Hui LS, Stanslas J, et al.
    Z Naturforsch C J Biosci, 2008 2 16;62(11-12):786-92.
    PMID: 18274278
    Two new xanthones, characterized as 4-(1,1-dimethylprop-2-enyl)-1,3,5,8-tetrahydroxyxanthone (1) and penangianaxanthone (2), with three known xanthones, cudratricusxanthone H (3), macluraxanthone C (4) and gerontoxanthone C (5), as well as friedelin and stigmasterol were isolated from the leaves of Garcinia penangiana. Their structures were elucidated by analysis of spectroscopic data and comparison of the NMR data with the literature ones. Significant cytotoxicity against DU-145, MCF-7 and NCI-H460 cancer cell lines was demonstrated by compounds 1-5, with IC50 values ranging from 3.5 to 72.8 microM.
    Matched MeSH terms: Garcinia/chemistry*; Xanthones/chemistry
  7. Fulltext Selective Arylation of 2-Bromo-4-chlorophenyl-2-bromobutanoate via a Pd-Catalyzed Suzuki Cross-Coupling Reaction and Its Electronic and Non-Linear Optical (NLO) Properties via DFT Studies
    Nazeer U, Rasool N, Mujahid A, Mansha A, Zubair M, Kosar N, et al.
    Molecules, 2020 Jul 31;25(15).
    PMID: 32752125 DOI: 10.3390/molecules25153521
    In the present study, 2-bromo-4-chlorophenyl-2-bromobutanoate (3) was synthesized via the reaction of 2-bromo-4-chlorophenol with 2-bromobutanoyl bromide in the presence of pyridine. A variety of 2-bromo-4-chlorophenyl-2-bromobutanoate derivatives (5a-f) were synthesized with moderate to good yields via a Pd-catalyzed Suzuki cross-coupling reaction. To find out the reactivity and electronic properties of the compounds, Frontier molecular orbital analysis, non-linear optical properties, and molecular electrostatic potential studies were performed.
    Matched MeSH terms: Hydrocarbons, Halogenated/chemistry*; Palladium/chemistry*
  8. Enantiomeric pair of copper(II) polypyridyl-alanine complexes: Effect of chirality on their interaction with biomolecules
    Ng CH, Chan CW, Lai JW, Ooi IH, Chong KV, Maah MJ, et al.
    J Inorg Biochem, 2016 07;160:1-11.
    PMID: 27105312 DOI: 10.1016/j.jinorgbio.2016.04.003
    Like chiral organic drugs, the chemical and biological properties of metal complexes can be dependent on chirality. Two pairs of [Cu(phen)(ala)(H2O)]X·xH2O (phen=1.10-phenanthroline: X=NO3(-); ala: l-alanine (l-ala), 1 and d-alanine (d-ala) 2; and (X=Cl(-); ala: l-ala, 3 and d-ala, 4) complex salts (x=number of lattice water molecules) have been synthesized and characterized. The crystal structure of 3 has been determined. The same pair of enantiomeric species, viz. [Cu(phen)(l-ala)(H2O)](+) and [Cu(phen)(d-ala)(H2O)](+), have been identified to be present in the aqueous solutions of both 1 and 3, and in those of both 2 and 4 respectively. Both 3 and 4 bind more strongly to ds(AT)6 than ds(CG)6. There is no or insignificant effect of the chirality of 3 and 4 on the production of hydroxyl radicals, binding to deoxyribonucleic acid from calf thymus (CT-DNA), ds(CG)6, G-quadruplex and 17-base pair duplex, and inhibition of both topoisomerase I and proteasome. Among the three proteasome proteolytic sites, the trypsin-like site is inhibited most strongly by these complexes. However, the chirality of 3 and 4 does affect the number of restriction enzymes inhibited, and their binding constants towards ds(AT)6 and serum albumin.
    Matched MeSH terms: Alanine/chemistry*; Copper/chemistry*; DNA/chemistry*; DNA Topoisomerases, Type I/chemistry; Phenanthrolines/chemistry; Pyridines/chemistry*; Serum Albumin/chemistry; Hydroxyl Radical/chemistry; Proteasome Endopeptidase Complex/chemistry*; Coordination Complexes/chemistry*; Topoisomerase I Inhibitors/chemistry
  9. Processing of coconut sap into sugar syrup using rotary evaporation, microwave, and open-heat evaporation techniques
    Asghar MT, Yusof YA, Mokhtar MN, Yaacob ME, Ghazali HM, Varith J, et al.
    J Sci Food Agric, 2020 Aug;100(10):4012-4019.
    PMID: 32337729 DOI: 10.1002/jsfa.10446
    BACKGROUND: Coconut sugar has a caramel color with a taste like brown sugar. It is commonly used as natural sweetener. However, coconut sugar has been produced from coconut sap using a traditional method that involves heating the sap at high temperature (>100 °C) in an open pan for a long period (3-5 h). This conventional method results in an over-cooked sugar, which leads to quality deterioration in terms of both its physical and chemical properties. The current study aimed to investigate the processing of coconut sap into sugar syrup using alternative processing techniques such as rotary vacuum evaporation (RE) and microwave evaporation (ME), comparing them with open-heat evaporation (OHE) technique.

    RESULTS: Coconut sugar syrup produced by rotary evaporation at 60 °C and 250 mbar vacuum (RE-60) required the shortest production time (12.2 min) and the lowest processing temperature (54.8 °C) when compared with ME (13 min and 103.2 °C) and OHE (46.8 min and 101.6 °C). It also had a light brownish color with a higher L* value (35.17) than the ME (29.84) and OHE (23.84) methods. It was found to contain higher amounts of monosaccharides (fructose and glucose) and lower amounts of disaccharides (sucrose). Furthermore, the amount of energy required for RE-60 (0.35 kWh) was much less than for OHE (0.83 kWh).

    CONCLUSION: This study provided an alternative processing method for the sugar processing industry to produce coconut sugar using the rotary evaporation method at 60 °C under 250 mbar vacuum with better physicochemical qualities, shorter processing time, and minimum input energy. © 2020 Society of Chemical Industry.

    Matched MeSH terms: Cocos/chemistry*; Fruit/chemistry
  10. Engineering pyrolysis biochar via single-step microwave steam activation for hazardous landfill leachate treatment
    Lam SS, Yek PNY, Ok YS, Chong CC, Liew RK, Tsang DCW, et al.
    J Hazard Mater, 2020 05 15;390:121649.
    PMID: 31753673 DOI: 10.1016/j.jhazmat.2019.121649
    Improving the sustainability and cost-effectiveness of biochar production is crucial to meet increased global market demand. Here, we developed a single-step microwave steam activation (STMSA) as a simplified yet efficient method to produce microwave activated biochar (MAB) from waste palm shell (WPS). The STMSA recorded a higher heating rate (70 °C/min) and higher conversion (45 wt%) of WPS into highly microporous MAB (micropore surface area of 679.22 m2/g) in contrast with the conventional heating approach (≤ 12-17 wt%). The MAB was then applied as biosorbent for hazardous landfill leachate (LL) treatment and the adsorption performance was compared with commercial activated carbon under different pH, adsorbent quantity, adsorbate concentrations, and contact times. The MAB demonstrated high adsorption capacity, achieving maximum adsorption efficiency at 595 mg/g and 65 % removal of chemical oxygen demand (COD) with 0.4 g/L of adsorbent amount under optimal acidic conditions (pH ≈ 2-3) after 24 h of contact time. The Freundlich isotherm and pseudo second-order kinetic models were well-fitted to explain the equilibrium adsorption and kinetics. The results indicate the viability of STMSA as a fast and efficient approach to produce activated biochar as a biosorbent for the treatment of hazardous landfill leachate.
    Matched MeSH terms: Charcoal/chemistry*; Water Pollutants, Chemical/chemistry*
  11. The phytochemical analysis and pharmacological potentials of husk and straw as paddy waste products
    Murtey MD, Seeni A
    J Sci Food Agric, 2020 Sep;100(12):4347-4352.
    PMID: 32248531 DOI: 10.1002/jsfa.10406
    Rice serves as a staple food for one-half of the global population. However, rice production, particularly the rice milling process, results in a substantial amount of paddy waste products (e.g. bran, husk and straw) annually. Because the potentials of bran have been extensively explored in prior studies, the present review focuses exclusively on the phytochemical analysis and pharmacological potentials of husk and straw. This comprehensive review establishes a solid foundation for promoting husk and straw as medicinal substances given their promising pharmacological potentials as bioactive compound sources with therapeutic functions. © 2020 Society of Chemical Industry.
    Matched MeSH terms: Oryza/chemistry*; Phytochemicals/chemistry*
  12. Isolation and identification of N6-isopentenyladenosine as the cytotoxic constituent of a marine sponge Oceanapia sp
    Nakamukai S, Ise Y, Ohtsuka S, Okada S, Matsunaga S
    Biosci Biotechnol Biochem, 2019 Nov;83(11):1985-1988.
    PMID: 31250707 DOI: 10.1080/09168451.2019.1630258
    N6-Isopentenyladenosine (i6A) was isolated from a marine sponge Oceanapia sp. as the major cytotoxic constituent along with N6-isopentenyladenosine 5'-monophosphate (i6AP) which was inactive. The structures of i6A and i6AP were assigned by a combination of the analysis of NMR spectroscopy and mass spectrometry. This is the first isolation of i6A and i6AP from a marine sponge.
    Matched MeSH terms: Isopentenyladenosine/chemistry*; Porifera/chemistry*
  13. Fulltext Green Synthesized Montmorillonite/Carrageenan/Fe3O4 Nanocomposites for pH-Responsive Release of Protocatechuic Acid and Its Anticancer Activity
    Yew YP, Shameli K, Mohamad SE, Lee KX, Teow SY
    Int J Mol Sci, 2020 Jul 09;21(14).
    PMID: 32659939 DOI: 10.3390/ijms21144851
    Discovery of a novel anticancer drug delivery agent is important to replace conventional cancer therapies which are often accompanied by undesired side effects. This study demonstrated the synthesis of superparamagnetic magnetite nanocomposites (Fe3O4-NCs) using a green method. Montmorillonite (MMT) was used as matrix support, while Fe3O4 nanoparticles (NPs) and carrageenan (CR) were used as filler and stabilizer, respectively. The combination of these materials resulted in a novel nanocomposite (MMT/CR/Fe3O4-NCs). A series of characterization experiments was conducted. The purity of MMT/CR/Fe3O4-NCs was confirmed by X-ray diffraction (XRD) analysis. High resolution transmission electron microscopy (HRTEM) analysis revealed the uniform and spherical shape of Fe3O4 NPs with an average particle size of 9.3 ± 1.2 nm. Vibrating sample magnetometer (VSM) analysis showed an Ms value of 2.16 emu/g with negligible coercivity which confirmed the superparamagnetic properties. Protocatechuic acid (PCA) was loaded onto the MMT/CR/Fe3O4-NCs and a drug release study showed that 15% and 92% of PCA was released at pH 7.4 and 4.8, respectively. Cytotoxicity assays showed that both MMT/CR/Fe3O4-NCs and MMT/CR/Fe3O4-PCA effectively killed HCT116 which is a colorectal cancer cell line. Dose-dependent inhibition was seen and the killing was enhanced two-fold by the PCA-loaded NCs (IC50-0.734 mg/mL) compared to the unloaded NCs (IC50-1.5 mg/mL). This study highlights the potential use of MMT/CR/Fe3O4-NCs as a biologically active pH-responsive drug delivery agent. Further investigations are warranted to delineate the mechanism of cell entry and cancer cell killing as well as to improve the therapeutic potential of MMT/CR/Fe3O4-NCs.
    Matched MeSH terms: Antineoplastic Agents/chemistry*; Bentonite/chemistry*; Carrageenan/chemistry*; Drug Carriers/chemistry; Ferric Compounds/chemistry*; Ferrosoferric Oxide/chemistry; Nanocomposites/chemistry*; Green Chemistry Technology/methods; Magnetite Nanoparticles/chemistry; Hydroxybenzoates/chemistry*
  14. Effect of Purification Methods on the Physicochemical and Thermodynamic Properties and Crystallization Kinetics of Medium-Chain, Medium-Long-Chain, and Long-Chain Diacylglycerols
    Wang S, Lee WJ, Wang Y, Tan CP, Lai OM, Wang Y
    J Agric Food Chem, 2020 Aug 05;68(31):8391-8403.
    PMID: 32511921 DOI: 10.1021/acs.jafc.0c01346
    Medium-chain diacylglycerol (MCD), medium-long-chain diacylglycerol (MLCD), and long-chain diacylglycerol (LCD) were prepared through enzymatic esterification using different conditions at temperatures of 55-70 °C and reaction times of 1.5-5 h and in the presence of 5-6% Novozym 435. Subsequently, purification was performed using three different techniques, namely, molecular distillation (MD), deodorization (DO), and silica gel column chromatography (SGCC). Variations in terms of the physicochemical and thermodynamic properties, crystallization properties, and kinetics of the diacylglycerols (DAGs) before and after purification were determined. Irrespective of the DAG chain lengths, SGCC was able to produce samples with high DAG purity (96-99 wt %), followed by MD (58-79 wt %) and DO (39-59 wt %). A higher 1,3-DAG/1,2-DAG ratio was recorded for all samples, with the highest ratio recorded for SGCC purified samples. Regardless of the purification techniques used, the solid fat content (SFC) profiles of crude samples with steep curves were altered post-purification, showing a gradual increment in SFC along with increasing temperature. Modification of the Avrami constant and coefficient suggested the modification of the crystal growth mechanism post-purification. Crystallization and melting temperatures of products with a higher DAG purity were shifted to a higher temperature region. Variations were also reflected in terms of the crystal polymorphism, whereby the α and β' crystals transitioned into the more stable β form in purified samples accompanied by modification in the microstructures and crystal sizes. However, there was insignificant change in the morphology of MLCD crystal after purification, except for the decrease in crystal sizes. In conclusion, synthesis of MCD, MLCD, and LCD comprising different DAG purities had distinctive SFC profiles, thermodynamic properties, crystallization kinetics, and crystal morphologies, which can be further incorporated into the preparation of a variety of fat products to obtain end products with desired characteristics.
    Matched MeSH terms: Diglycerides/chemistry*; Lipase/chemistry
  15. Nanoporous biomaterials for uremic toxin adsorption in artificial kidney systems: A review
    Cheah WK, Ishikawa K, Othman R, Yeoh FY
    J Biomed Mater Res B Appl Biomater, 2017 07;105(5):1232-1240.
    PMID: 26913694 DOI: 10.1002/jbm.b.33475
    Hemodialysis, one of the earliest artificial kidney systems, removes uremic toxins via diffusion through a semipermeable porous membrane into the dialysate fluid. Miniaturization of the present hemodialysis system into a portable and wearable device to maintain continuous removal of uremic toxins would require that the amount of dialysate used within a closed-system is greatly reduced. Diffused uremic toxins within a closed-system dialysate need to be removed to maintain the optimum concentration gradient for continuous uremic toxin removal by the dialyzer. In this dialysate regenerative system, adsorption of uremic toxins by nanoporous biomaterials is essential. Throughout the years of artificial kidney development, activated carbon has been identified as a potential adsorbent for uremic toxins. Adsorption of uremic toxins necessitates nanoporous biomaterials, especially activated carbon. Nanoporous biomaterials are also utilized in hemoperfusion for uremic toxin removal. Further miniaturization of artificial kidney system and improvements on uremic toxin adsorption capacity would require high performance nanoporous biomaterials which possess not only higher surface area, controlled pore size, but also designed architecture or structure and surface functional groups. This article reviews on various nanoporous biomaterials used in current artificial kidney systems and several emerging nanoporous biomaterials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1232-1240, 2017.
    Matched MeSH terms: Biocompatible Materials/chemistry*; Toxins, Biological/chemistry*
  16. Fabrication and characterization of DLC coated microdimples on hip prosthesis heads
    Choudhury D, Ay Ching H, Mamat AB, Cizek J, Abu Osman NA, Vrbka M, et al.
    J Biomed Mater Res B Appl Biomater, 2015 Jul;103(5):1002-12.
    PMID: 25220737 DOI: 10.1002/jbm.b.33274
    Diamond like carbon (DLC) is applied as a thin film onto substrates to obtain desired surface properties such as increased hardness and corrosion resistance, and decreased friction and wear rate. Microdimple is an advanced surface modification technique enhancing the tribological performance. In this study, DLC coated microdimples were fabricated on hip prosthesis heads and their mechanical, material and surface properties were characterized. An Electro discharge machining (EDM) oriented microdrilling was utilized to fabricate a defined microdimple array (diameter of 300 µm, depth of 70 µm, and pitch of 900 µm) on stainless steel (SS) hip prosthesis heads. The dimpled surfaces were then coated by hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) layers by using a magnetron sputtering technology. A preliminary tribology test was conducted on these fabricated surfaces against a ceramic ball in simulated hip joint conditions. It was found that the fabricated dimples were perpendicular to the spherical surfaces and no cutting-tools wear debris was detected inside the individual dimples. The a-C:H and Ta-C coatings increased the hardness at both the dimple edges and the nondimpled region. The tribology test showed a significant reduction in friction coefficient for coated surfaces regardless of microdimple arrays: the lowest friction coefficient was found for the a-C:H samples (µ = 0.084), followed by Ta-C (µ = 0.119), as compared to the SS surface (µ = 0.248).
    Matched MeSH terms: Carbon/chemistry*; Coated Materials, Biocompatible/chemistry*
  17. QSPR prediction of the hydroxyl radical rate constant of water contaminants
    Borhani TN, Saniedanesh M, Bagheri M, Lim JS
    Water Res, 2016 07 01;98:344-53.
    PMID: 27124124 DOI: 10.1016/j.watres.2016.04.038
    In advanced oxidation processes (AOPs), the aqueous hydroxyl radical (HO) acts as a strong oxidant to react with organic contaminants. The hydroxyl radical rate constant (kHO) is important for evaluating and modelling of the AOPs. In this study, quantitative structure-property relationship (QSPR) method is applied to model the hydroxyl radical rate constant for a diverse dataset of 457 water contaminants from 27 various chemical classes. The constricted binary particle swarm optimization and multiple-linear regression (BPSO-MLR) are used to obtain the best model with eight theoretical descriptors. An optimized feed forward neural network (FFNN) is developed to investigate the complex performance of the selected molecular parameters with kHO. Although the FFNN prediction results are more accurate than those obtained using BPSO-MLR, the application of the latter is much more convenient. Various internal and external validation techniques indicate that the obtained models could predict the logarithmic hydroxyl radical rate constants of a large number of water contaminants with less than 4% absolute relative error. Finally, the above-mentioned proposed models are compared to those reported earlier and the structural factors contributing to the AOP degradation efficiency are discussed.
    Matched MeSH terms: Water/chemistry; Hydroxyl Radical/chemistry*
  18. Current regulatory requirements and practical approaches for stability analysis of pharmaceutical products: A comprehensive review
    Sengupta P, Chatterjee B, Tekade RK
    Int J Pharm, 2018 May 30;543(1-2):328-344.
    PMID: 29635054 DOI: 10.1016/j.ijpharm.2018.04.007
    Different regulatory guidelines recommend establishing stability profile of pharmaceuticals at the time of drug development. The expiry date, retesting period and storage conditions of active drugs or products are established through stability analysis. Several regulatory guidelines exist for stability testing of pharmaceuticals. Mostly, ICH stability guidelines are followed in practice. This guideline recommends to validate stability indicating method using forced degradation samples that contains all possible degradation impurities. ICH guidelines provide general recommendations for inclusion of stability indicating parameters in a stability testing protocol. However, those guidelines do not provide specific requirements and experimental methodology to be followed for stability studies. Due to this gap, often confusion arises in the scientific community in designing stability testing protocol. Therefore, significant variations are observed in reported literature in selection of stability indicating parameters. Procedural dissimilarity amongst reported stability studies is also evident. This review discusses the regulatory guidelines and procedures to follow in performing stability testing of pharmaceuticals. Scope of this review also includes recommendations on practical approaches for designing stability testing protocol to fulfill current regulatory requirements for drug substances and their formulations.
    Matched MeSH terms: Chemistry, Pharmaceutical/legislation & jurisprudence*; Chemistry, Pharmaceutical/methods
  19. Fulltext Macrolactin A as a Novel Inhibitory Agent for SARS-CoV-2 Mpro: Bioinformatics Approach
    Bharadwaj KK, Sarkar T, Ghosh A, Baishya D, Rabha B, Panda MK, et al.
    Appl Biochem Biotechnol, 2021 Oct;193(10):3371-3394.
    PMID: 34212286 DOI: 10.1007/s12010-021-03608-7
    COVID-19 is a disease that puts most of the world on lockdown and the search for therapeutic drugs is still ongoing. Therefore, this study used in silico screening to identify natural bioactive compounds from fruits, herbaceous plants, and marine invertebrates that are able to inhibit protease activity in SARS-CoV-2 (PDB: 6LU7). We have used extensive screening strategies such as drug likeliness, antiviral activity value prediction, molecular docking, ADME, molecular dynamics (MD) simulation, and MM/GBSA. A total of 17 compounds were shortlisted using Lipinski's rule in which 5 compounds showed significant predicted antiviral activity values. Among these 5, only 2 compounds, Macrolactin A and Stachyflin, showed good binding energy of -9.22 and -8.00 kcal/mol, respectively, within the binding pocket of the Mpro catalytic residues (HIS 41 and CYS 145). These two compounds were further analyzed to determine their ADME properties. The ADME evaluation of these 2 compounds suggested that they could be effective in developing therapeutic drugs to be used in clinical trials. MD simulations showed that protein-ligand complexes of Macrolactin A and Stachyflin with the target receptor (6LU7) were stable for 100 nanoseconds. The MM/GBSA calculations of Mpro-Macrolactin A complex indicated higher binding free energy (-42.58 ± 6.35 kcal/mol). Dynamic cross-correlation matrix (DCCM) and principal component analysis (PCA) on the residual movement in the MD trajectories further confirmed the stability of Macrolactin A bound state with 6LU7. In conclusion, this study showed that marine natural compound Macrolactin A could be an effective therapeutic inhibitor against SARS-CoV-2 protease (6LU7). Additional in vitro and in vivo validations are strongly needed to determine the efficacy and therapeutic dose of Macrolactin A in biological systems.
    Matched MeSH terms: Cysteine Proteinase Inhibitors/chemistry*; Macrolides/chemistry*
  20. Production of new cellulose nanomaterial from red algae marine biomass Gelidium elegans
    Chen YW, Lee HV, Juan JC, Phang SM
    Carbohydr Polym, 2016 Oct 20;151:1210-1219.
    PMID: 27474672 DOI: 10.1016/j.carbpol.2016.06.083
    Nanocellulose was successfully isolated from Gelidium elegans red algae marine biomass. The red algae fiber was treated in three stages namely alkalization, bleaching treatment and acid hydrolysis treatment. Morphological analysis was performed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). TEM results revealed that the isolated nanocellulose had the average diameter and length of 21.8±11.1nm and of 547.3±23.7nm, respectively. Fourier transform infrared (FTIR) spectroscopy proved that the non-cellulosic polysaccharides components were progressively removed during the chemically treatment, and the final derived materials composed of cellulose parent molecular structure. X-ray diffraction (XRD) study showed that the crystallinity of yielded product had been improved after each successive treatments subjected to the treated fiber. The prepared nano-dimensional cellulose demonstrated a network-like structure with higher crystallinity (73%) than that of untreated fiber (33%), and possessed of good thermal stability which is suitable for nanocomposite material.
    Matched MeSH terms: Cellulose/chemistry*; Nanostructures/chemistry*
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