Polyhydroxyalkanoates (PHAs) has been investigated for more than eighty years. Ever since then, the scientists are kept on synthesizing and developing new polymers and application to suit human interests nowadays. The resourcefulness of PHAs has made them a good candidates for the study of their potential in a variety of areas from biomedical/medical fields to food, packaging, textile and household material. In medical field (specifically in tissue engineering application), producing a biocompatible 3-D scaffold with adaptable physical properties are essential. However, to the best of our knowledge, scaffolds from PHB and PHBV with thickness greater than 1 mm have not been produced yet. In this work, PHB and PHBV porous 3-D scaffolds with an improved thickness greater than 4 mm was fabricated using conventional method of solvent-casting particulate-leaching (SCPL). A preliminary assessment on the improved thickness 3-D scaffolds was carried out to examine its pore interconnectivity by using non-invasive color staining method. The vertical cross sections image of the stained scaffolds was analyzed by image analyzer software. This technique was considered simple, fast and cost effective method prior to the usage of super accurate analytical instruments (micro-computed tomography). The results showed that over 80% of the pores have been interconnected with the adjacent pores. Moreover, there was a good correlation between the predicted pore interconnectivity and porosity. These results indicated how well a simple technique can do by giving an overview of the internal morphology of a porous 3-D structure material.
Bio-pesticides are becoming increasingly important as pest management tools in various cropping systems in the tropics essentially to remedy problems associated with the indiscriminate use of ‘hard’ and non-environmental friendly inorganic pesticide. In these past few decades, many bio-pesticidal products, both microbial-based (bacteria, fungi, microsprodia, entomopathogenic nematodes and viruses) and plant-based botanicals (rotenone and azadiracthin) have been studied for their use against insect pests in the tropics. In this study, the effects of the concentration process with respect to the yield of rotenone (mg) and its concentration (mg/mL) are presented extensively. The raw plants were collected from Kota Johor Lama, Johor and sorted to obtain the roots and stems. Only the roots and stems were utilized as raw materials of the extraction process. The rotenone from roots and stems was extracted using the normal soaking extraction (NSE) at 28 to 30oC with 95% (v/v) of acetone as a solvent and the solvent-to-solid ratio of 10 mL/g. The extraction was carried out for 24 h. Next, the liquid crude extract was concentrated using the rotary evaporator at 50oC and 80 mbar of vacuum pressure to remove approximately 90% of solvent. The fractions of the liquid crude extract were collected (15 min/mL/fraction), diluted (1/100 with acetone) and cleaned up (to remove any fine debris) prior to determination of rotenone content (mg) and concentration (mg/mL) by using the reverse-phase high performance liquid chromatography (RP-HPLC). Finally, the results showed that there was a significant effect of thermal degradation or dissipation of rotenone content at higher operating temperature (greater than 40oC) with a rapid rotenone reduction for the first 15 min of exposure. The possibilities for better exploitation and identification of the effective operating parameters based on the above mentioned results will be perhaps discussed in the future.
Ultra-high temperature is a process that involves heating of milk to a very high temperature to produce sterile milk products.
However, food poisoning due to consumption of UHT milk still happen in Malaysia. This study was done to develop a
film that is made by poly(L-lactic acid) (PLLA) to detect the presence of microorganisms in UHT milk products. UHT milk
that was used in this study was full cream milk. Contaminated milk that contained Bacillus cereus was made to conduct
a model system on the relationship between colony forming unit of microorganisms and contact angle. Contaminated
milk was also used as a control sample to study the difference of milk properties between fresh and contaminated milk.
Physicochemical analysis (Brix, colour, pH and contact angle) and microbiological analysis (total plate count) were
done to UHT milk sample as soon as the packaging of the milk was unsealed. Analysis was done with 30 min time interval
until 4 h and 30 min since the unsealing of packaging. The results showed that presence of microorganisms in UHT milk
was detected after the milk product was unsealed and exposed to environment for 3 h and 30 min. Contact angle resulted
from the presence of microorganisms in UHT milk was 64.34 - 65.44° with its colony forming unit, 2.1 – 3.9 cfu/mL.
Therefore, the potential usage of contact angle on PLLA thin film with respect to colony forming unit (cfu) in detecting
the presence of microorganisms in UHT milk product was attained and well modelled.
[BMIM]OTf and alcohol-based DES combination with a selected organic solvent (acetone and acetonitrile) have
been proven to efficiently extracting rotenone (isoflavonoid biopesticide) compound compared to individual organic
solvents. Their efficiency builds up interest to study the solvent-solute interaction that occurs between both selected
solvent systems with rotenone. The interaction study was analyzed using FTIR, 1D-NMR and 2D- NMR (NOESY, HMBC).
Correlation portrayed by NOESY and HMBC of [BMIM]OTf - standard rotenone mixture predicted probable hydrogen
bonding between the oxygen of rotenone with acidic proton C2-H of [BMIM]OTf. While for the alcohol-based DESrotenone
mixture, the correlation shows probable interaction to occur between methyl and methoxy group rotenone
with the hydroxyl group of 1,4-butanediol. In conclusion, potential hydrogen bonding that occurs between solvent
and solute aid towards the solvent efficiency in extracting rotenone compound while emphasizing on the low cost and
green mediated solvent systems.
A 50Hz glow discharge He/CH4
plasma was generated and applied for the glass surface modification to reduce the powder
adhesion on wall of spray dryer. The hydrophobicity of the samples determined by the water droplet contact angle and
adhesion weight on glass, dependent on the CH4 flow rate and plasma exposure time. The presence of CH3
groups and
higher surface roughness of the plasma treated glass were the factors for its hydrophobicity development. Response
surface methodology (RSM) results using central composite rotatable design (CCRD) showed that optimal responses
were obtained by the combination of parameters, CH4
gas flow rate = 3 sccm and exposure time = 10 min. In optimum
conditions, the contact angle increased by 47% and the weight of the adhesion reduced by 38% (w/w). The plasma
treatment could enhance the value of the contact angle and thus reduced the adhesion on the spray dryer glass surface.