Efficiency of Polyphenol Extraction from Artificial Honey Using C18 Cartridges and Amberlite„ XAD-2 Resin: A Comparative Study

A comparative study of the extraction efficiency of nine known polyphenols [phenolic acids (benzoic acid, dihydroxybenzoic acid, gallic acid, trans-cinnamic acid, and vanillic acid) and flavonoids (naringenin, naringin, quercetin, and rutin)] was conducted by deliberately adding the polyphenols to an artificial honey solution and performing solid phase extraction (SPE). Two SPE methods were compared: one using Amberlite XAD-2 resin and another one using a C18 cartridge. A gradient high performance liquid chromatography system with an RP18 column and photodiode array detector was utilized to analyze the extracted polyphenols. The mean percent of recovery from the C18 cartridges was 74.2%, while that from the Amberlite XAD-2 resin was 43.7%. The recoveries of vanillic acid, naringin, and rutin were excellent (>90%); however, gallic acid was not obtained when C18 cartridges were used. Additionally, the reusability of Amberlite XAD-2 resin was investigated, revealing that the mean recovery of polyphenols decreased from 43.7% (1st extraction) to 29.3% (3rd extraction). It was concluded that although Amberlite XAD-2 resin yielded a higher number of compounds, C18 cartridges gave a better extraction recovery. The lower recovery seen for the Amberlite XAD-2 resin also cannot be compensated by repeated extractions due to the gradual decrease of extraction recovery when reused

Light emission, light detection and strain sensing with nanocrystalline graphene

Graphene is of increasing interest for optoelectronic applications exploiting light detection, light emission and light modulation. Intrinsically light matter interaction in graphene is of a broadband type. However by integrating graphene into optical micro cavities also narrow band light emitters and detectors have been demonstrated. The devices benefit from the transparency, conductivity and processability of the atomically thin material. To this end we explore in this work the feasibility of replacing graphene by nanocrystalline graphene, a material which can be grown on dielectric surfaces without catalyst by graphitization of polymeric films. We have studied the formation of nanocrystalline graphene on various substrates and under different graphitization conditions. The samples were characterized by resistance, optical transmission, Raman, X-ray photoelectron spectroscopy, atomic force microscopy and electron microscopy measurements. The conducting and transparent wafer-scale material with nanometer grain size was also patterned and integrated into devices for studying light-matter interaction. The measurements show that nanocrystalline graphene can be exploited as an incandescent emitter and bolometric detector similar to crystalline graphene. Moreover the material exhibits piezoresistive behavior which makes nanocrystalline graphene interesting for transparent strain sensors

Global Prevalence of Zika and Chikungunya Coinfection:A Systematic Review and Meta-Analysis

Zika virus (ZIKV) and chikungunya virus (CHIKV) are arthropod-borne viruses with significant pathogenicity, posing a substantial health and economic burden on a global scale. Moreover, ZIKV-CHIKV coinfection imposes additional therapeutic challenges as there is no specific treatment for ZIKV or CHIKV infection. While a growing number of studies have documented the ZIKV-CHIKV coinfection, there is currently a lack of conclusive reports on this coinfection. Therefore, we performed a systematic review and meta-analysis to determine the true statistics of ZIKV-CHIKV coinfection in the global human population. Relevant studies were searched for in PubMed, Scopus, and Google Scholar without limitation in terms of language or publication date. A total of 33 studies containing 41,460 participants were included in this meta-analysis. The study protocol was registered with PROSPERO under the registration number CRD42020176409. The pooled prevalence and confidence intervals of ZIKV-CHIKV coinfection were computed using a random-effects model. The study estimated a combined global prevalence rate of 1.0% [95% CI: 0.7–1.2] for the occurrence of ZIKV-CHIKV coinfection. The region of North America (Mexico, Haiti, and Nicaragua) and the country of Haiti demonstrated maximum prevalence rates of 2.8% [95% CI: 1.5–4.1] and 3.5% [95% CI: 0.2–6.8], respectively. Moreover, the prevalence of coinfection was found to be higher in the paediatric group (2.1% [95% CI: 0.0–4.2]) in comparison with the adult group (0.7% [95% CI: 0.2–1.1]). These findings suggest that the occurrence of ZIKV-CHIKV coinfection varies geographically and by age group. The results of this meta-analysis will guide future investigations seeking to understand the underlying reasons for these variations and the causes of coinfection and to develop targeted prevention and control strategies

Prevalence and characteristics of fever in adult and paediatric patients with coronavirus disease 2019 (COVID-19):a systematic review and meta-analysis of 17515 patients

BackgroundCoronavirus disease 2019 (COVID-19), a pandemic disease caused by the severe acute respiratory syndrome coronavirus 2 started to spread globally since December 2019 from Wuhan, China. Fever has been observed as one of the most common clinical manifestations, although the prevalence and characteristics of fever in adult and paediatric COVID-19 patients is inconclusive. We aimed to conduct a systematic review and meta-analysis to estimate the overall pooled prevalence of fever and chills in addition to fever characteristics (low, medium, and high temperature) in both adult and paediatric COVID-19 patients.MethodsThe protocol of this systematic review and meta-analysis was registered with PROSPERO (CRD42020176327). PubMed, Scopus, ScienceDirect and Google Scholar databases were searched between 1st December 2019 and 3rd April 2020 without language restrictions. Both adult (≥18 years) and paediatric (ResultsWe identified 2055 studies, of which 197 studies (n = 24266) were included in the systematic review and 167 studies with 17142 adults and 373 paediatrics were included in the meta-analysis. Overall, the pooled prevalence of fever in adult and paediatric COVID-19 patients were 79.43% [95% CI: 77.05-81.80, I2 = 95%] and 45.86% [95% CI: 35.24-56.48, I2 = 78%], respectively. Besides, 14.45% [95% CI: 10.59-18.32, I2 = 88%] of the adult COVID-19 patients were accompanied with chills. In adult COVID-19 patients, the prevalence of medium-grade fever (44.33%) was higher compared to low- (38.16%) and high-grade fever (14.71%). In addition, the risk of both low (RR: 2.34, 95% CI: 1.69-3.22, pConclusionsThe prevalence of fever in adult COVID-19 patients was high, however, 54.14% of paediatric COVID-19 patients did not exhibit fever as an initial clinical feature. Prevalence and risk of low and medium-grade fevers were higher compared to high-grade fever

PROLONGED HEATING OF HONEY INCREASES ITS ANTIOXIDANT POTENTIAL BUT DECREASES ITS ANTIMICROBIAL ACTIVITY

Background: Honey is renowned for its antioxidant, antimicrobial and medicinal properties. It is typically heated and filtered during processing to avoid crystallization. However, few studies have reported its heating effect and the antioxidant and antimicrobial activities of honey. Materials and Methods: In this study, honey samples were collected from eight different honey-producing sites in Bangladesh and heated to 50ºC, 70ºC and 90ºC for 12 hours, while the antioxidant potentials and antimicrobial properties of the heated samples were compared with those of the unheated samples. Antimicrobial properties were investigated against one Gram-positive and eight Gram-negative bacteria. Other physicochemical and biochemical properties were also determined. Results: Interestingly, there was a proportionate increase in the amount of antioxidant compounds (phenolics and flavonoids) as well as antioxidant potentials proportional with the amount of heat introduced, whereas the antimicrobial properties of the honey samples were reduced with increasing heat. Conclusion: In conclusion, though prolonged heat treatment of honey can increase its antioxidant potential, antimicrobial activities are compromised

The Influence of Transition Metals Addition on the Corrosion Resistance of Nanocrystalline Al Alloys Produced by Mechanical Alloying

The corrosion resistance of nanocrystalline Al, Al-10 wt. % Fe and Al-10 wt. % Fe-5 wt. % Cr alloys was investigated in 3.5% NaCl solution using cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) techniques. The alloys were fabricated using mechanical alloying (MA) and heat induction sintering. When compared with the corrosion resistance of pure Al, the experimental results indicated that the addition of 10 wt. % Fe and 10 wt. % Fe-5 wt. % Cr to pure Al has resulted in an enhancement in the corrosion resistance of these newly fabricated alloys. The resistance to corrosion is due to enhanced microstructural stability along with the formation of stable oxide layer