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The purpose of this study is to modify guar gum (GG) into guar gum acetate (GGA) and phthaloyl guar gum (PHGG) by transesterification and phthaloylation, respectively.

GG has been modified into GGA through transesterification reaction between GG and vinyl acetate and PHGG through esterification reaction with phthalic anhydride. The modified GG was characterized by solubility test, Fourier-transform infra-red (FTIR) spectroscopy, proton nuclear magnetic resonance (¹H NMR) spectroscopy, X-ray diffractometry (XRD) and thermogravimetric analysis. Swelling properties of GGA and PHGG hydrogels in water were evaluated.

These two types of modified GG have better solubility such as in dimethyl sulfoxide and N,N-dimethylformamide but no true organosolubility was achieved. The modifications were confirmed through FTIR with new absorption peaks at 1,733 cm⁻¹ for GGA and 1,709 cm⁻¹ for PHGG coupled with observed substitution peaks at 1.80 to 2.20 ppm and 7.40 to 7.90 ppm, respectively, from ¹H NMR spectroscopies. XRD revealed both GGA and PHGG are less crystalline than native GG. GGA was found to be more thermally stable than native GG, whereas PHGG was slightly less thermally stable than native GG. The swelling property in distilled water for native GG, PHGG and GGA was 918.43 ± 46.62%, 537.04 ± 2.87% and 393.04 ± 13.42%, respectively.

The GGA and PHGG hydrogels are expected to be useful for biomedical fields such as tissue engineering and drug-delivery.

Modifications of native GG into GGA using vinyl acetate and PHGG using phthalic anhydride are novel.

Regular monitoring of bacteria, especially Escherichia coli, in wastewater is crucial to ensure the maintenance of public health. Amperometric detection proves to be a fast, sensitive and economically viable solution for E. coli enumeration. This paper reported a prototype amperometric sensor based on PANI-ZnO-NiO nanocomposite thin films prepared by sol–gel method and irradiated with gamma ray. The purpose of this study is to investigate the sensor performance of PANI-ZnO-NiO nanocomposite thin films to detect E. coli in water.

The films were varied with different compositions of ZnO and NiO by using the formula PANI-(ZnO)_1-x-(NiO)_x, with x = 0.2, 0.4, 0.6 and 0.8. PANI-ZnO-NiO nanocomposite thin films were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM) to study the crystallinity and surface morphology of the films. The sensor performance was conducted using the current–voltage (I-V) measurement by testing the films in clean water and E. coli solution.

XRD diffractograms show the peaks of ZnO (1 0 0) and NiO (1 0 2). AFM analysis shows the surface roughness, and the grain size of PANI-ZnO-NiO thin films decreases when the concentration ratios of NiO increased. I-V curves show the difference in current flow, where the current in E. coli solution is higher than the clean water.

PANI-(ZnO)_1-x-(NiO)_x nanocomposite thin film with the highest concentration of ZnO performed the highest sensitivity among the other concentrations, which can be used to indicate the presence of E. coli bacteria in water.

The purpose of this paper is to examine the influence of institutional quality on the export-led growth (ELG) with global evidence of a panel of 119 countries.

The research framework looks at the role of exports in promoting growth via. good institutional quality. The methods of testing are panel data approach of causality, and fixed and random effects models.

Empirical results show that good Institutional quality mediates the ELG relationship in general, and middle income group in specific. The legal institutional quality has significant positive impact, whereas political and economic institutional quality have significant negative impact on ELG for all sampled countries.

The Kuncic’s (2014) institutional quality data are annually available between 1990 and 2010. Therefore, time series analysis for individual country is bias with 21 observations. And, this study ignores other potential variables such as capital, labor, real exchange rate, and so on, may possibly contribute to omitted-variables bias.

Policymakers may well utilize institutional quality reforms either in terms of improving existing institutional quality or enhancing “second-best” institutions as a policy instrument to reap success from export-oriented growth strategies.

Existing studies on ELG have ignored institutional quality as a relevant variable. It looks at the three institutional quality indicators, namely political, economic, and legal in ELG framework.