Preparation and characterization of biodegradable poly(vinyl alcohol)/starch blends

Poly(vinylalcohol) was blended with a fairly acetylated cassava starch and made into film of various percentages. Their mechanical properties, biodegradability and surface morphology were estimated and studied. The poly(vinyl alcohol)/starch blends show good modulus and biodegradability that make it suitable for disposable packaging applications in which 50 percent starch/Poly(vinyl alcohol) blends shows a modulus of approximately 199100Nm-2 and 59.25 percent weight lost after 18 days of standard biodegradation test.Keywords: Starch, Acetylation, Biodegradation, Poly(vinyl alcohol), Polymer blend

New liquid crystals in the series of 1, 3, 5-triazine compounds containing azobenzene at the peripheral arms

Novel liquid crystal materials whose molecular structures consist of disc-like 1,3,5-triazine unit as a central core and three rod-like azobenzenes as the peripheral arms unit has been prepared and characterized by spectroscopic methods, and X-ray diffraction. The Series of compounds were prepared by nucleophilic addition of the primary amino nucleophile to 1,3,5-triazine electrophilic ring via alkyl spacers in presence of potassium carbonate as hydrochloride acceptor. Differencial scanning calorimetry (DSC), polarizing optical microscopy and x-ray diffraction confirmed Smectic mesophase textures of the materials. Increase in the polymethylene spacer length influence the thermal and phase stability of the compounds studied

Synthesis and characterization of a star-shaped nematic discotic liquid crystal containing 1, 3, 5-triazine core and bisazobenzene at the peripheral arms

A new three arm liquid crystalline material containing bisazobenzene and linked by flexible spacers (4-propyloxy-[4-biphenyloxyalkyl]-4`-(4-phenylazo)azobenzene has been synthesized and characterized by spectroscopic methods. The transition temperatures and phase behaviors were studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The synthesized compounds exhibited nematic discotic phase and the stability of the layer depends on the spacer length for the compounds

The use of castor oil as a flame retardant in polyurethane foam

Thirteen polyurethane foam samples were prepared with varying quantity of castor oil as a reactant with polyisocyanate and their flammability test was carried out using various flame test procedures. Physical properties of the foam samples were found to increase with the increasing in the quantity of castor oil. Results of flammability test shows that the flame propagation rate and the after-glow time are relatively reduced with the corresponding increase in the quantity of castor oil. The add-on test and the ignition time increases with increase in the quantity of castor oil as flame retardant. Foam with 8cm3 and 10cm3 quantity of castor oil as flame retardant seems to be perfect and required for good quality and quantity of polyurethane foam.Keywords: Castor oil, Polyurethane forms, Flame retardant. Polyol, Polyisocyanat

A firm-level analysis of the upstream-downstream dichotomy in the oil-stock nexus

In this paper, we query whether the stock prices of nonintegrated firms in the upstream and downstream sectors of the global oil supply chain respond symmetrically to changes in oil prices. This inquiry relates to the “homogenous expectation” assumption among investors and fund managers pertaining to the returns and variances of assets of specialized firms operating in upstream and downstream sectors of the supply chain. Motivated by the Arbitrage Pricing Theory, we formulate a Panel Autoregressive Distributed Lag (PARDL) model, which explains the possible macroeconomic factors in the oil-stock nexus as well as any inherent persistence and heterogeneity effects due to large cross-sections and time. In accordance with the Shin et al. (2014) approach, a Nonlinear Panel ARDL model is also formulated to test for possible asymmetric responses of the nonintegrated oil firms to positive and negative changes in the oil price. Our findings indicate that the stock prices of upstream and downstream firms move in contrasting directions in response to changes in the benchmark crude oil prices in the long-run. Specifically, we show that the stock prices of upstream sector firms increased in response to an increase in oil prices, while the reverse holds for the stock prices of downstream firms. In the short run, returns on the stock of firms in both sectors increase following an increase in oil prices; however, downstream firms’ stock returns decreased in response to negative oil price shocks. The findings further show that both sectors respond differently to episodic changes in market conditions that emanated from the global financial crisis. However, upstream firms show a stronger response to changing market conditions than their downstream counterparts

PALM OIL PRICE–EXCHANGE RATE NEXUS IN INDONESIA AND MALAYSIA

In this study, we extend the literature analyzing the predictive content of commodity prices for exchange rates by examining the role of palm oil price. Our analysis focuses on Indonesia and Malaysia, the two top producers and exporters of palm oil, and utilizes daily data covering the period from December 12, 2011 to March 29, 2021, which is partitioned into two sub-samples based on the COVID-19 pandemic. Relying on a methodology that accommodates some salient features of the variables of interest, we find that on average the in-sample predictability of palm oil price for exchange rate movements is stronger for Indonesia than for Malaysia. While Indonesia’s exchange rate appreciates due to a rise in palm oil price regardless of the choice of predictive model, Malaysia’s exchange rate only appreciates after adjusting for oil price. However, both exchange rates do not seem to be resilient to the COVID-19 pandemic as they depreciate amidst dwindling palm oil price. Similar outcomes are observed for the out-of-sample predictability analysis. We highlight avenues for future research and the implications of our results for portfolio diversification strategies.In this study, we extend the literature analyzing the predictive content of commodity prices for exchange rates by examining the role of palm oil price. Our analysis focuses on Indonesia and Malaysia, the two top producers and exporters of palm oil, and utilizes daily data covering the period from December 12, 2011 to March 29, 2021, which is partitioned into two sub-samples based on the COVID-19 pandemic. Relying on a methodology that accommodates some salient features of the variables of interest, we find that on average the in-sample predictability of palm oil price for exchange rate movements is stronger for Indonesia than for Malaysia. While Indonesia’s exchange rate appreciates due to a rise in palm oil price regardless of the choice of predictive model, Malaysia’s exchange rate only appreciates after adjusting for oil price. However, both exchange rates do not seem to be resilient to the COVID-19 pandemic as they depreciate amidst dwindling palm oil price. Similar outcomes are observed for the out-of-sample predictability analysis. We highlight avenues for future research and the implications of our results for portfolio diversification strategies

In vitro comparative activity of ciprofloxacin and enrofloxacin against clinical isolates from chickens in Benue State, Nigeria

This study compares the in vitro activities of enrofloxacin and its main metabolite ciprofloxacin against clinical Escherichia coli and non-lactose fermenting enterobacteria isolates from chickens. Ten (10) Escherichia coli and 8 non lactose fermenting enterobacteriaceae species isolated from a pool of clinical cases at the Microbiology Laboratory of the Veterinary Teaching Hospital, University of Agriculture Makurdi were used in this study. Ten-fold serial dilution of 10 varying concentrations (0.1-50μg/mL) of enrofloxacin and ciprofloxacin were tested against the isolates in vitro by Bauer’s disc-diffusion method to determine and compare their antimicrobial activities against the isolates. The 18 isolates tested were susceptible to both enrofloxacin and ciprofloxacin, and their mean values in the susceptibility of Escherichia coli and non-lactose fermenters were significantly different (p < 0.01). The study concluded that the clinical isolates are susceptible to both enrofloxacin and ciprofloxacin though ciprofloxacin exhibit higher activity. Comparatively, ciprofloxacin was found to be more potent than enrofloxacin and the difference statistically significant. Ciprofloxacin was recommended as a better choice in the treatment of bacterial infections of chicken in this area compared to enrofloxacin. It was also recommended that proper steps should be taken in the administration of antimicrobials so as to reduce the incidences of bacterial resistance.Keywords:  Escherichia coli, Non-lactose fermenter, Antimicrobials, Ciprofloxacin. Enrofloxacin, Chicke

Acute effects of Hibiscus sabdariffa calyces on postprandial blood pressure, vascular function, blood lipids, biomarkers of insulin resistance and inflammation in humans

The acute impact of Hibiscus sabdariffa calyces (HSC) extract on postprandial vascular function and other cardiometabolic risk factors have not been studied previously. This study investigated the acute impact of HSC extract consumption on blood pressure (BP), vascular function and other cardiometabolic risk markers. Twenty-five men with 1% to 10% cardiovascular disease (CVD) risk (determined by QRISK 2) were randomised to consume either 250 mL of the aqueous extract of HSC or water with breakfast in a randomised, controlled, single-blinded, 2-meal cross-over study (ClinicalTrials.gov, NTC02165553) with a two weeks washout period between study days. BP was measured at baseline and hourly for 4 h. Flow mediated dilatation (FMD) of the branchial artery was measured at baseline, 2 and 4 h post intervention drink consumption. Acute consumption of aqueous extract of HSC caused a significant increase in % FMD ( < 0.001), a non-significant decrease in systolic BP (SBP) and diastolic BP (DBP); non-significant increase in urinary and plasma nitric oxide (NOx) and reduced response of serum glucose, plasma insulin, serum triacylglycerol and C-reactive protein (CRP) levels; significant ( = 0.026) improvement in the area under systemic antioxidant response curve (0 to 2 h); no significant changes in arterial stiffness following the acute consumption of the extract of HSC. Gallic acid, 4-O-methylgallic acid, 3-O-methylgallic acid and hippuric acid reached a maximum plasma concentration at 1 to 2 h post consumption of the extract of HSC. The extract of HSC improved postprandial vascular function and may be a useful dietary strategy to reduce endothelial dysfunction and CVD risk, although this requires confirmation

MULTIBAND MILLIMETER WAVE T-SHAPED ANTENNA WITH OPTIMIZED PATCH PARAMETER USING PARTICLE SWARM OPTIMIZATION

This paper proposed a simple T-shaped patch antenna for millimeter waveband frequency operation. Millimeter wave is a frequency ranges between 30GHz to 300GHz in an electromagnetic spectrum. The proposed antenna consists of T-shape radiating patch mounted on rectangular substrate (FR4-4) and microstrip line for antenna feeding. An evolutionary algorithm called particle swarm optimization was used to optimize the length and width of the proposed antenna patch. The proposed antenna gives triple bands with central frequencies at 42GHz, 51.5GHz and 60GHz. The antenna offers minimum return loss of -19db, -24db and -19.5db at 42GHz, 51.5GHz and 60GHz respectively. The return loss impedance bandwidth of 5GHz for the first band, 8.4GHz for the second band and 5GHz for the third band was obtained. The proposed antenna was analyzed using Ansoft High Frequency Structure Simulator (HFSS) and MATLAB 2013. Radiation characteristics of this patch antenna are observed at various resonating frequencies.  http://dx.doi.org/10.4314/njt.v36i3.3