Caffeine in Chiang Rai tea infusions: Effects of tea variety,type, leaf form,and infusion conditions

Caffeine in Chiang Rai tea infusions was found to be dependent on infusion conditions (water temperature and infusion time), and leaf form (non-ground or ground) but independent of tea variety and type. For non-ground leaf samples, the higher the water temperature and the longer the infusion time, the higher the caffeine concentrations in tea infusions. After infusing for longer than 15 min, the dissolution rate of caffeine became slower and the concentration was essentially constant. For ground leaves, the caffeine content was not influenced by infusion time. Caffeine concentrations in tea infusions from Camellia sinensis var. sinensis (26.8 ± 0.81 and 22.3 ± 5.55 mg/100 ml for ground and non-ground samples, respectively) were not significantly different from that of Camellia sinensis var. assamica (24.4 ± 0.66 and 20.3 ± 5.07 mg/100 ml for ground and non-ground samples, respectively). The difference in caffeine concentration between green tea (28.1 ± 8.19 mg/100 ml) and oolong tea (20.3 ± 1.52 mg/100 ml) was not statistically significant.     

Rapid antioxidant capacity screening in herbal extracts using a simple flow injection-spectrophotometric system

A simple flow injection (FI)-spectrophotometric system for the screening of antioxidant capacity in herbal extracts was developed. The analysis was based on the color disappearance due to the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical by antioxidant compounds. DPPH and ascorbic acid were used as reagent and antioxidant standard, respectively. Effects of the DPPH concentration, DPPH flow rate, and reaction coil length on sensitivity were studied. The optimized condition provided the linear range of 0.010-0.300 mM ascorbic acid with less than 5%RSD_(n = 10). Detection limit and quantitation limit were 0.004 and 0.013 mM, respectively. Comparison of antioxidant capacity in some herbal extracts determined by the FI system and a standard method was carried out and no significant difference was obtained.     

SV119-gold nanocage conjugates: a new platform for targeting cancer cells via sigma-2 receptors

We have functionalized the surface of gold nanocages with SV119, a synthetic small molecule specific to sigma-2 receptors, and then demonstrated the capability of this new class of conjugates for targeting cancer cells.     

Electrospun poly(L-lactic acid) fiber mats containing a crude Garcinia cowa extract for wound dressing applications

The copolymerization of sodium-2-acrylamido-2-methylpropane sulfonate with acrylonitrile and acrylamide in water has been studied at different concentrations of monomers, the initiator and the external electrolyte (NaCl). It was shown that an increase in the total concentration of the monomers leads to enriching the copolymers with units of the ionic monomer. A decrease in the initiator concentration causes the increase of the nitrile content in the product. Using of reactivity ratios r₁ and r₂ was shown to be invalid for this system as it does not allow one to appropriately predict the copolymer composition or its microstructure. The observed effects of significant dependence of copolymers composition on these factors have been explained by the influence of prepolymerization processes of formation of monomer assemblies and aggregates of monomers with growing macroradicals.     

Use of banana purée from three indigenous Thai cultivars as food matrices for probiotics and application in bio‐set‐type yoghurt production

This research studied the use of banana purée from three indigenous Thai cultivars (Kluai Hom Thong, Kluai Namwa and Kluai Khai) as probiotic carrying agents in food and application in bio‐set‐type yoghurt. Kluai Khai purée had promising indication of prebiotic activity on Lactobacillus paracasei Lpc‐37 with the highest probiotic activity score. When Lpc‐37 cell was incorporated into Kluai Khai purée, its cell counts increased by 0.8 log CFU g^?1 and it adhered to purée, as seen by the proliferating cells. Therefore, Kluai Khai purée mixed with Lpc‐37 was selected for the production of bio‐set‐type yoghurt. The results showed that viable cells increased more than 0.8 log CFU g^?1 during storage. This study reflected the achievement of using Kluai Khai purée as food matrix for carrying ‘active probiotic cells’ in bio‐yoghurt production. This methodologically developed prototype could be an interesting alternative for value adding of indigenous fruits.     

Interaction of trace elements in acid mine drainage solution with humic acid

The release of metal ions from a coal mining tailing area, Lamphun, Northern Thailand, is studied by leaching tests. Considerable amounts of Mn, Fe, Al, Ni and Co are dissolved in both simulated rain water (pH 4) and 10 mg L(-1) humic acid (HA) solution (Aldrich humic acid, pH 7). Due to the presence of oxidizing pyrite and sulfide minerals, the pH in both leachates decreases down to approximately 3 combined with high sulfate concentrations typical to acid mine drainage (AMD) water composition. Interaction of the acidic leachates upon mixing with ground- and surface water containing natural organic matter is simulated by subsequent dilution (1:100; 1:200; 1:300; 1:500) with a 10 mg L(-1) HA solution (ionic strength: 10(-3) mol L(-1)). Combining asymmetric flow field-flow fractionation (AsFlFFF) with UV/Vis and ICP-MS detection allows for the investigation of metal ion interaction with HA colloid and colloid size evolution. Formation of colloid aggregates is observed by filtration and AsFlFFF depending on the degree of the dilution. While the average HA size is initially found to be 2 nm, metal-HA complexes are always found to be larger. Such observation is attributed to a metal induced HA agglomeration, which is found even at low coverage of HA functional groups with metal ions. Increasing the metal ion to HA ratio, the HA bound metal ions and the HA entities are growing in size from <3 to >450 nm. At high metal ion to HA ratios, precipitation of FeOOH phases and HA agglomeration due to colloid charge neutralization by complete saturation of HA complexing sites are responsible for the fact that most of Fe and Al precipitate and are found in a size fraction >450 nm. In the more diluted solutions, HA is more relevant as a carrier for metal ion mobilization.     

Determination of perfluorinated compounds (PFCs) in solid and liquid phase river water samples in Chao Phraya River, Thailand

Perfluorinated compounds (PFCs), especially perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are fully fluorinated organic compounds, which have been used in many industrial applications. These chemicals have contaminated surface water all over the world even in developing countries like Thailand. The previous study showed the contamination in Chao Phraya River in 2006 and 2007. The purposes of this field study were to determine the solid and liquid phase of PFCs contamination in Chao Phraya River and to compare the changes of PFC concentration in 2008. Surveys were conducted in the lower reach of Chao Phraya River in the industrialized area. A solid phase extraction (SPE) coupled with HPLC-ESI-MS/MS were used for the analysis for ten PFCs. Ten PFCs were analyzed to identify the contamination in both solid and liquid phases. PFCs were detected in both the solid and liquid phase in every sample. PFOA was the most dominant PFC while PFPA and PFOS were also highly detected in most samples. The average loadings of PFPA, PFOA and PFOS in Chao Phraya River were 94.3, 284.6 and 93.4 g/d, respectively. PFOS concentrations did not show differences between 2006 and 2008. However, PFOA concentrations were higher in 2008/5/26, while comparing other samplings. The ratio of solid:liquid PFPA (2.1:1.0) [(ng/g)/(ng/L)] was lower than PFOA (13.9:1.0) [(ng/g)/(ng/L)] and PFOS (17.6:1.0) [(ng/g)/(ng/L)]. The shorter chain (more hydrophilic) PFC was better to dissolve in water rather than adsorb onto suspended solids. PFOS also showed more potential to attach in the suspended solids than PFOA.     

Cycling copper flip chip interconnects

Use of flip chip assembly on compound semiconductor circuits is relatively new. Although solder bumping has been around for a while, use of copper bumps is also new. This discussion is intended to provide some initial data on the melding of copper flip chip bumps and compound semiconductor technologies, with respect to thermal excursion testing––cycling. For comparison, it is known that attempts to accelerate degradation caused by thermal excursions on solder bumps can result in irregular failure mechanisms. This work shows that on-chip power cycling can be used to cause identical failure mechanisms to those caused by normal temperature cycling.     

The use of cationic fluoroprobes to characterize ionic pathways in organic coatings

The spatial distribution of pathways by which ions enter and move through organic coatings was examined with the use of molecular fluoroprobes. A bis-phenol-A epoxy coating (10–15 μm thick) on titanium was anodically polarized in an electrolyte containing an activated fluoroprobe. Confocal scanning laser microscopy (CSLM) was used at an excitation/emission of 580/602 nm to characterize the penetration pattern of the Ca²⁺-X-Rhod-1 fluoroprobe. Both discrete fluorescence sites and regional fluoroprobe uptake were observed within a single epoxy coating. The chemical and/or physical reasons for the increased susceptibility of ionic species at these sites and regions are not yet known, but now provide focus to the local material sources for loss of barrier properties. This proof-of-concept experiment provides a means to attain unambiguous evidence for the mode of ion entry and passage through organic coatings. These experiments open a new avenue for the characterization of organic coatings.     

Electrospun poly(l-lactic acid) fiber mats containing crude Garcinia mangostana extracts for use as wound dressings

Poly(l-lactic acid) (PLLA) fiber mats containing two types of crude Garcinia mangostana Linn. (GM) extract [i.e., dichloromethane extract (dGM) and acetone extract (aGM)] were successfully prepared by electrospinning process. Both the neat and the GM-loaded PLLA fibers were smooth, with the average diameters ranging between 0.77 and 1.14 μm. The release characteristics of GM from the GM-loaded PLLA fiber mats were carried out by total immersion method in acetate buffer or simulated body fluid that contained 0.5 % v/v Tween 80 and 3 % v/v methanol (hereafter, A/T/M or S/T/M medium) at either 32 or 37 °C, respectively. The maximum cumulative amounts of GM released from the GM-loaded PLLA fiber mats in the S/T/M medium were greater than those in the A/T/M medium. Moreover, the cumulative amounts of GM released from the aGM-loaded PLLA fiber mats were greater than those from the dGM-loaded PLLA fiber mats in both types of medium. The antibacterial activity of the dGM-loaded PLLA fiber mats was greatest against Staphylococcus aureus DMST 20654, while that of the aGM-loaded PLLA fiber mats was greatest against S. aureus ATCC 25923 and S. epidermidis. Lastly, only the dGM-loaded PLLA fiber mats at extraction ratio of 10 mg mL^?1 were toxic to the human dermal fibroblasts.