Ahmed Jalal Khan Chowdhury

Impact of chitosan composites and chitosan nanoparticle composites on various drug delivery systems: A review

Chitosan is a promising biopolymer for drug delivery systems. Because of its beneficial properties, chitosan is widely used in biomedical and pharmaceutical fields. In this review, we summarize the physicochemical and drug delivery properties of chitosan, selected studies on utilization of chitosan and chitosan-based nanoparticle composites in various drug delivery systems, and selected studies on the application of chitosan films in both drug delivery and wound healing. Chitosan is considered the most important polysaccharide for various drug delivery purposes because of its cationic character and primary amino groups, which are responsible for its many properties such as mucoadhesion, controlled drug release, transfection, in situ gelation, and efflux pump inhibitory properties and permeation enhancement. This review can enhance our understanding of drug delivery systems particularly in cases where chitosan drug-loaded nanoparticles are applied.

Synthesis, spectroscopic and chromatographic studies of sunflower oil biodiesel using optimized base catalyzed methanolysis

Methyl esters from vegetable oils have attracted a great deal of interest as substitute for petrodiesel to reduce dependence on imported petroleum and provide an alternate and sustainable source for fuel with more benign environmental properties. In the present study biodiesel was prepared from sunflower seed oil by transesterification by alkali-catalyzed methanolysis. The fuel properties of sunflower oil biodiesel were determined and discussed in the light of ASTM D6751 standards for biodiesel. The sunflower oil biodiesel was chemically characterized with analytical techniques like FT-IR, and NMR (1H and 13C). The chemical composition of sunflower oil biodiesel was determined by GC–MS. Various fatty acid methyl esters (FAMEs) were identified by retention time data and verified by mass fragmentation patterns. The percentage conversion of triglycerides to the corresponding methyl esters determined by 1H NMR was 87.33% which was quite in good agreement with the practically observed yield of 85.1%.

Environmental characteristics of clay and clay-based minerals

Abstract Clay is an inherently occurring material constituted with fined-grained mineral. The minerals are generally less than 2 microns and occur to be plastic in water content which solidify when dried. In the earth surface, clay represents the most available mineral and forms rocks known as shale and is the major component of sedimentary rocks. The small size of the particles and their unique crystal structures give clay materials special properties. These properties include: cation exchange capabilities, plastic behaviour when wet, catalytic abilities, swelling behaviour, and low permeability. They give to clay and clay-based minerals higher application in many industries and processes. To acknowledge all the features of clay and clay-based minerals, the understanding of their properties especially the cation exchange capability which affects the mechanical and physical properties of the clay is important, and also to acquire information about the crystal structure of clay mineral in general and montmorillonite especially. The purpose of this laboratory is to illustrate the importance of chemistry on the physical properties of montmorillonite, the clay mineral most often used to isolate dangerous waste materials from the environment.

Assessing Nesting Status of Green Turtles, Chelonia Mydas in Perak, Malaysia

The nesting of green turtle (Chelonia mydas) was monitored from 1998 untill 2013 along the beaches of Pasir Panjang, Segari, Perak. The objective of the study is to assess the nesting status of green turtles in Perak, Peninsular Malaysia in terms of total nests, eggs, survival hatchings, and density of visitors. A total number of green turtle nests found for 16 years were 1,019 nests and varied from 10 to 220 nests per year. Meanwhile, the sum of eggs collected for 16 years were 107,820 eggs, and varied from 553 to 20,881 eggs per year. The temporal pattern of nesting indicates year-round nesting in Perak in most years within the 16 years period. The peak season of nesting was estimated to occur between May and June. Survival hatchlings varied from 23.33% (2,071 hatchlings) to 55.03% (5,018 hatchlings) from 1998 to 2013. The density of visitors was not uniformly distributed among the years, and shows a sign of decline especially from 2006 onwards. This publication provides basic knowledge of green turtle nesting population in Perak, and would be helpful in upgrading the conservation program in Malaysia. In future, we hope 1) for an increase in manpower to obtain accurate nesting records along the nesting beaches during nocturnal survey and, 2) to include the breeding biology data such as nest placement, emergence hour, and morphological characteristics of green turtle.

Biological Activities and Extraction Technologies of Pheonix dactylifera: A Review

Date palm (Pheonix dactylifera L.) has long been known for its medical benefits. In this review, the therapeutic properties of P. dactylifera are presented in light of the analysis of huge past reviews that reported the bioactivities of both flesh and seed of this fruit. The reported bioactivities of P. dactylifera included antioxidants, anti-cancer, aphrodisiac, antimicrobial, and anti-diabetic properties. This review additionally highlights the extraction technologies (Soxhlet, maceration, heat under reflux, supercritical fluid extraction (SFE) and microwave assisted extraction) that were utilized as part of the extraction of P. dactylifera. This is because the quality and amount of the extraction yield depend on the extraction technology used. Accordingly, this review aims for underlining the potentials of P. dactylifera by compiling available data on the bioactivities and extraction technologies used to set the directions for the improvement of future research of this fruit.

Importance of Sand Particle Size and Temperature for Nesting Success of Green Turtles in Penang Island, Malaysia

Abstract The microhabitats of green turtle (Chelonia mydas) nests were investigated to identify key factors influencing nesting success by monitoring both successful nests (n = 43) and aborted nests (n = 106) created by the same individuals (n = 9) from September 2013 to September 2014 on Penang Island, Malaysia. The effect of sand particle size on nesting success was significant, suggesting that green turtles tend to abort nesting at sites with sands of particle sizes < 1 mm. In addition, nests were successful at superficial sand temperatures less than 32.95°C.

Review on antibacterial biocomposites of structural laminated veneer lumber.

In this review, the characteristics and applications of structural laminated veneer lumber made from planted forest wood is introduced, and its preparation is explained, including various tree species and slab qualities, treatments for multiple effects and reinforced composites. The relevant factors in the bonding technology and pressing processes as well as the mechanical properties, research direction and application prospects of structural laminated veneer lumber made from planted forest wood are discussed.

Selective isolation and antagonistic activity of actinomycetes from mangrove forest of Pahang, Malaysia

This study aimed to isolate and evaluate the antagonistic potential of actinomycetes from mangrove forest of Pahang, Malaysia. Sediment samples from seven different sites were pretreated using wet heat and dry heat methods followed by dilution plating on eight isolation media. In total, 4850 isolates were successfully recovered, with inorganic salt–starch agar displaying the highest percentage of recovery (31.7%), followed by actinomycete isolation agar (24.1%). The wet heat pretreatment was found to be more effective in the enumeration of actinomycetes, since 81.4% of total isolates were yielded using this technique, whereas dry heat treatment was better in the enumeration of spore-forming actinomycetes. After both pretreatments, Streptomyces-like and Micromonospora-like isolates were the most predominant. The antagonistic activities of the representative isolates were evaluated using the cross-streak method. In total, 78 isolates were active against at least one of the test organisms. Among them, 28.2% exhibited antibacterial activity, 23.1% exhibited antifungal activity and 48.7% displayed both. Nine isolates demonstrated broad antagonism by inhibiting the growth of all test organisms. The presence of a relatively large number of bioactive isolates suggests that Pahang mangrove forest is a potential source of actinomycetes with biosynthetic capabilities.