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Recent Modifications and Validation of QuEChERS-dSPE Coupled to LC–MS and GC–MS Instruments for Determination of Pesticide/Agrochemical Residues in Fruits and Vegetables: Review
No full textFruits and vegetables constitute a major type of food consumed daily apart from whole grains. Unfortunately, the residual deposits of pesticides in these products are becoming a major health concern for human consumption. Consequently, the outcome of the long-term accumulation of pesticide residues has posed many health issues to both humans and animals in the environment. However, the residues have previously been determined using conventionally known techniques, which include liquid-liquid extraction, solid-phase extraction (SPE) and the recently used liquidphase microextraction techniques. Despite the positive technological effects of these methods, their limitations include; time-consuming, operational difficulty, use of toxic organic solvents, low selective property and expensive extraction setups, with shorter lifespan of instrumental performances. Thus, the potential and maximum use of these methods for pesticides residue determination has resulted in the urgent need for better techniques that will overcome the highlighted drawbacks. Alternatively, attention has been drawn recently towards the use of quick, easy, cheap, effective, rugged and safe technique (QuEChERS) coupled with dispersive solid-phase extraction (dSPE) to overcome the setback challenges experienced by the previous technologies. Conclusively, the reviewed QuEChERS-dSPE techniques and the recent cleanup modifications justifiably prove to be reliable for routine determination and monitoring the concentration levels of pesticide residues using advanced instruments such as high-performance liquid chromatography, liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry
Panduratin A induces protective autophagy in melanoma via the AMPK and mTOR pathway
No full textBackground: Targeting autophagy is emerging as a promising strategy in cancer therapeutics in recent years. Autophagy can be modulated to drive cancer cell deaths that are notoriously resistant to apoptotic-inducing drugs. In addition, autophagy has been implicated as a prosurvival mechanism in mediating cancer chemoresistance. Our previous study has demonstrated that Panduratin A (PA), a plant-derived active compound exploits ER-stress-mediated apoptosis as its cytotoxic mechanism on melanoma. Purpose: Our previous proteomics analysis revealed that treatment with PA resulted in the upregulation of an autophagy marker, LC3B in melanoma cells. Therefore, the present study sought to investigate the role of PA-induced autophagy in melanoma cells. Methods: Transmission electron microscopy was performed for examination of autophagic ultra-structures in PA-treated A375 cells. Cytoplasmic LC3B and p62/SQSMT1 punctate structures were detected using immunofluorescene staining. Expression levels of LC3B II, p62/SQSMT1, ATG 12, Beclin 1, phospho S6 (ser235/236), phospho AMPK (Thr172) and cleaved PARP were evaluated by western blotting. Results: Autophagosomes, autolysosomes and punctuates of LC3 proteins could be observed in PA-treated A375 cells. PA-induced autophagy in A375 melanoma cells was found to be mediated through the inhibition of mTOR signaling and activation of AMPK pathway. Furthermore, we showed that PA-induced apoptosis was increased in the presence of an autophagy inhibitor, signifying the cytoprotective effect of PA-induced autophagy in melanoma cells. Conclusion: Taken together, results from the present study suggest that the inhibition of autophagy by targeting mTOR and AMPK could potentiate the cytotoxicity effects of PA on melanoma cells
CdSe Species Decorated TiO2 Nanotubes Film Via Chemical Bath Deposition for Enhancing Photoelectrochemical Water Splitting Performance
No full textBackground: The conversion of sunlight to electrical power has been dominated by solidstate junction devices, often made of silicon. However, this dominance is now being challenged by the emergence of the new generation of water splitting cell (integration of photovoltaic system with an electrolyzer to generate clean and portable H2 energy carrier. This cell normally is based on nanocrystalline materials, which offers the prospect of cheap fabrication together with other attractive feature such as high chemical stability and flexibility in aqueous solution under evolving oxygen (O2) gases. However, nanocrystalline materials are facing few drawback such as recombination losses of charge carriers and less response under visible spectrum. Therefore, an effort to minimize the recombination losses of charge carriers and extended the spectral response of TiO2 NTs into visible spectrum by incorporating an optimum amount of lower band gap and suitable band edge position semiconductor (cadmium selenide [CdSe]) into the lattice of TiO2 NTs. Methods: An efficient approach has been demonstrated in this research work to enhance the solardriven photoelectrochemical (PEC) water splitting performance by decorating CdSe species into highly ordered TiO2 nanotubes (NTs) film through a facile and cost-effective chemical bath deposition. Morphology, chemical properties, and electronic structures have been studied. Results: A maximum photocurrent density of ~2.50 mA/cm2 at 0.6V versus Ag/AgCl electrode was exhibited by TiO2 NTs with the presence of approximately 1 at % of CdSe species. The presence of CdSe species offered an improvement of photocurrent density under solar irradiation due to the effective mediators to trap the photo-induced electrons and minimizes the recombination of charge carriers within the lattice of TiO2 NTs. Conclusion: Hybrid CdSe-TiO2 NTs were successfully fabricated through chemical bath deposition method in order to study the synergistic coupling effect of CdSe with TiO2 NTs on the PEC performance. By bathing pure TiO2 NTs film in a 5 mM CdSe precursor solution extensively covered by approximately 1 at % CdSe exhibited the highest jp of 2.50 mA/cm2 among the samples. However, excessive deposition (≥5 mM) was neither negatively affected by the self-organized NTs nor decreased in jp. This condition inferred that higher ionic product (Cd and Se ions) leaded to rapid ion-by-ion condensation or adsorption of colloidal particles clogged the opening pore’s mouth of TiO2 NTs. Thus, an improvement in the photoresponse was observed when optimum amount (~ 1 at %) of the CdSe was deposited on TiO2 NTs film
Truncated and spheroidal Ag nanoparticles: a matter of size transformation
No full textThe ordered arrays of anisotropic mesostructure metal nanoparticle (diameter size in the range of 15 to 200 nm) characteristics are indeed influenced by the combined effect of packing constraints and inter-particle interactions, that is, the two morphological factors that strongly influence the creation of the particles’ shape. In this work, we studied on how the degree of truncation of Ag nanoparticles authorised the mesostructured morphologies and particle orientation preferences within the mesosparticle arrays. The Ag represented the best and most versatile candidate and known for its highest electrical conductivities among other transition metals in periodic table. The interest is motivated by the need to understand the inevitable morphological transformation from mesoscopic to microscopic states evolve within the scope of progressive aggregation of atomic constituents of Ag system. The grazing information obtained from HR-TEM shows that Ag mesosparticles of highly truncated flake are assembled in fcc-type mesostructure, similar to the arrays formed by microscopic quasi-spherical structure, but with significantly reduced packing density and different growth orientations. The detailed information on the size and microstructure transformation have been gathered by fast Fourier transform (FFT) of HR-TEM images, allowing us to figure out the role of Ag defects that anchored the variation in crystallite growth of different mean diameter size particles. The influences on the details of the nanostructures have to be deeply understood to promote practical applications for such outstanding Ag material
Incidence of methicillin resistant Staphylococcus aureus (MRSA) in burn intensive care unit: a systematic review
No full textBackground Burn victims admitted in burn intensive care units (ICU) are at a high risk of nosocomial infections generated by methicillin resistant Staphylococcus aureus (MRSA). This systematic review aims to estimate the incidence of MRSA among burn patients admitted to the ICU setting, with an emphasis on the incidence rate and antibiotic resistance profile of the MRSA strains. Methods A systematic literature search was performed in five electronic databases limited to publication dates from 1 st January 2000 until 31 st August 2017. After screening n=481 articles, n=21 were found to meet the inclusion criteria of this systematic review. Results Results from the meta-analysis revealed that the risk for MRSA isolates in the burn ICU was 55.0% higher (OR 0.55, 95%CI 0.32-0.94). Therefore, timely testing, appropriate hygiene practice and suggested wound care must be practiced while handling such patients. Conclusion Further studies are needed to identify the risk factors of MRSA infections among burn patients and to develop new antimicrobial agents for MRSA infections
VIV study of an elastically mounted cylinder having low mass-damping ratio using RANS model
No full textThis study addresses vortex-induced vibration analysis by an elastic rigid cylinder oscillating free in cross flow direction subject to low mass damping ratio. Two-dimensional Reynold-Averaged Navier-Stokes equations (RAN) for this purpose are simulated. Analysis is carried out for range of reduced velocity = 2–16 which corresponds to Reynolds number 1700–14,000. The mass-ratio is 2.4 and mass-damping ratio 0.0013. Previously, similar studies have been performed numerically but are limited to achieve maximum cylinder response. In the current study, comparatively higher value of maximum amplitude of cylinder is computed. However delay in transition from ‘upper branch’ to ‘lower branch’ is noticed. In addition to maximum amplitude, other hydrodynamic coefficients are also discussed. The results extracted from current simulations are compared with previous experimental studies in literature
Synthesis and characterization of novel binuclear task-specific ionic liquid: an efficient and sustainable sulfonic-functionalized ionic liquid for one-pot synthesis of xanthenes
No full textA new binuclear sulfonic-functionalized ionic liquid was synthesized in two steps and its dual solvent-catalytic activity was studied for the synthesis of a variety of xanthenes under mild conditions. The simple experimental and sustainable procedure, good yield of the desired products within short reaction times, and recyclability of the ionic liquid are some advantages of the present strategy, and the current work shows the great importance of task-specific ionic liquids in organic synthesis
Synthesis and characterization of some novel 4-arylglyoxal-chromene derivatives in the presence of a polymeric catalyst and biological evaluation against Escherichia coli
No full textA poly(N-vinylimidazole)-catalyzed one-pot multicomponent reaction for the synthesis of 2-amino-4H-benzo[g]chromenes containing acyl group on the 4H-chromene ring has been developed. The products were obtained in generally good to excellent yields in the presence of low loading of poly(N-vinylimidazole) as a reusable basic catalyst via this synthetic strategy. Importantly, the catalyst has the unique ability of being easily separated and recycled. The products were screened for their antibacterial activity against Escherichia coli. The results of antibacterial studies showed that three 4-aroylchromene derivatives completely inhibited E. coli at 32 mg cm−3, whereas other derivatives were either moderately active or inactive up to 64 mg cm−3. Highest antimicrobial activity was observed when the phenylglyoxal hydrate was substituted with fluoro, nitro, and methoxy groups at para position
Micropropagation of nucellar embryos and their histological comparative study for regeneration ability with other explants of kinnow mandarin (Citrus reticulata blanco)
No full textPolyembryony is the most beneficial and distinct character in citrus seeds. This characteristic can be beneficial in citrus improvement programs. Nucellar embryos developed from nucellar wall in citrus seeds along with zygotic embryo are found to have high plants regeneration ability in comparison to zygotic embryos. Under In vitro culture conditions, nucellar embryos were detected and multiplied on MT media with 0.5ml of coconut water along with 50g/L sucrose. These nucellar embryonic tissues were also regenerated on MT media supplemented with 0.5 mg/L BAP and 0.5 mg/L kinetin. Many shoots were regenerated from nucellar embryonic tissue; these shoots were rooted on MT media supplemented with IBA 0.5mg/L and NAA 0.1 mg/L in addition to activated charcoal 0.5gm/L. The resulting plantlets were acclimatized in the green house. After micropropagation, histological studies of nucellar embryonic tissues were carried out under fluorescence microscope to examine their high regeneration ability in comparison with usual plant parts, like seeds, shoots as well as with tissue culture stages including embryogenic and non-embryogenic callus. It was found that nucellar embryos have more regeneration ability as compared to usual plant parts and other tissue culture stages
Home blood pressure control status in 2017‐2018 for hypertension specialist centers in Asia: Results of the Asia BP@Home study
No full textA self-measured home blood pressure (BP)-guided strategy is an effective practical approach to hypertension management. The Asia BP@Home study is the first designed to investigate current home BP control status in different Asian countries/regions using standardized home BP measurements taken with the same validated home BP monitoring device with data memory. We enrolled 1443 medicated hypertensive patients from 15 Asian specialist centers in 11 countries/regions between April 2017 and March 2018. BP was relatively well controlled in 68.2% of patients using a morning home systolic BP (SBP) cutoff of <135 mm Hg, and in 55.1% of patients using a clinic SBP cutoff of <140 mm Hg. When cutoff values were changed to the 2017 AHA/ACC threshold (SBP <130 mm Hg), 53.6% of patients were well controlled for morning home SBP. Using clinic 140 mm Hg and morning home 135 mm Hg SBP thresholds, the proportion of patients with well-controlled hypertension (46%) was higher than for uncontrolled sustained (22%), white-coat (23%), and masked uncontrolled (9%) hypertension, with significant country/regional differences. Home BP variability in Asian countries was high, and varied by country/region. In conclusion, the Asia BP@Home study demonstrated that home BP is relatively well controlled at hypertension specialist centers in Asia. However, almost half of patients remain uncontrolled for morning BP according to new guidelines, with significant country/regional differences. Strict home BP control should be beneficial in Asian populations. The findings of this study are important to facilitate development of health policies focused on reducing cardiovascular complications in Asia