Muhammad Z. Ahmad

Self-Assembled 3D ZnO Porous Structures with Exposed Reactive {0001} Facets and Their Enhanced Gas Sensitivity

Complex three-dimensional structures comprised of porous ZnO plates were synthesized in a controlled fashion by hydrothermal methods. Through subtle changes to reaction conditions, the ZnO structures could be self-assembled from 20 nm thick nanosheets into grass-like and flower-like structures which led to the exposure of high proportions of ZnO {0001} crystal facets for both these materials. The measured surface area of the flower-like and the grass, or platelet-like ZnO samples were 72.8 and 52.4 m2·g−1, respectively. Gas sensing results demonstrated that the porous, flower-like ZnO structures exhibited enhanced sensing performance towards NO2 gas compared with either grass-like ZnO or commercially sourced ZnO nanoparticle samples. The porous, flower-like ZnO structures provided a high surface area which enhanced the ZnO gas sensor response. X-ray photoelectron spectroscopy characterization revealed that flower-like ZnO samples possessed a higher percentage of oxygen vacancies than the other ZnO sample-types, which also contributed to their excellent gas sensing performance.

Reflectance Response of Optical Fiber Coated With Carbon Nanotubes for Aqueous Ethanol Sensing

Ethanol is a highly flammable chemical and is widely used for medical and industrial applications. In this paper, optical sensing performance of aqueous ethanol with different concentrations is investigated using multimode fiber coated with carbon nanotubes (CNT). The multimode optical fiber tip is coated with CNT via a drop-casting technique and is annealed at 70 °C to improve the binding of the nanomaterial to the silica fiber. The optical fiber tip and the CNT sensing layer are microcharacterized using field emission scanning electron microscopy, Raman spectroscopy, and X-ray diffraction techniques. The reflectance response of the developed fiber sensor is measured using a spectrophotometer in the optical wavelength range of 500-800 nm. Upon exposure to ethanol with concentration ranges of 5%-80%, the sensor reflectance reduced proportionally. The dynamic response decreased by 4% when the sensor is exposed to ethanol with concentration of 80% in distilled water. It is found that the sensor shows fast response and recovery as low as 38 and 49 s, respectively.

Goniothalamus: Phytochemical and Ethnobotanical Review

Goniothalamus species are used in widespread medicines for abortion, anti-aging, body pains, rheumatism, skin complaints, typhoid fever, tympanites, stomach ache and fever. The present study reviews the distribution of species along with their synonyms, their traditional usage, and correlated chemical compounds of Goniothalamus species with stress on the authentication of their ethnobotanical uses. The findings in some Goniothalamus species suggest that the chemical nature of their derivatives, such as acetogenins and styryl-lactones, may justify the use of these species against cancer in Asian traditional medicines due to their cytotoxic potential.

FAST DEVELOPMENT OF RP-HPLC METHOD FOR ESTIMATION OF RUTIN FROM AQUEOUS FRACTION OF NEW POLYHERBAL FORMULATION CONTAINING CLINACANTHUS NUTANS AND ELEPHANTOPUS SCABER

Herbal medicinal products contain a blend of phytochemicals; each of these contains many chemical compounds that may give the anticipated activity. Therefore, it is very vital to analyse and evaluate the quality of various active constituents and markers. Objective of the study was to develop and validate stability indicating RP-HPLC gradient method for simultaneous estimation of rutin as biomarker from an Aqueous fraction of the new polyherbal formulation of Clinacanthus nutans and Elephantopus scaber. A Shimadzu HPLC was utilized to perform the analysis which was equipped with anautosampler, column oven, and UV/VIS detector. An HPLC column used was Merck Licrochart Purospher Start RP 18 column (250mm, 4.6 mm i.d, 5μm pore size).The temperature was maintained at 40.0 oC throughout the study. The mobile phase was a binary mixture of methanol–water, 1:1 (v/v), adjusted to pH 3.0 with glacial acetic acid. The flow rate was 1 mL min. Absorbance was monitored at λ = 360 nm. Average Retention time, variance and standard deviation of rutin from aqueous fraction of the polyherbal formulation at different concentration was found 4.1327, 0.00157 and 0.0396 respectively. Coefficient correlation of standard and sample was found linear R=0.9991 and R= 0.998 respectively. The P value of standard and sample was found significant (P <0.0001). The proposed analytical method was found to be fast and stable. It is recommended as a part of more reliable qualitative and quantitative analysis of new herbal formulation in the treatment of the wound.

Non-aqueous synthesis of In2O3 nanoparticles and its NO2 gas sensing properties

An indium trioxide (In2O3) nanoparticle based conductometric sensor has been fabricated and tested towards NO2 gas. Novel chemical synthesis method was developed, in which benzylamine was mixed with indium acetate to form In(OH)3 as a precursor to form In2O3. Micro-characterization results revealed that the average size of the In2O3 nanoparticles is 8 nm and the particles have a cubic crystalline phase. Sensors exhibited very high sensitivities towards NO2 at an operating temperature of 150°C. Fast response and recovery with good repeatability along with stable baseline were observed.