Effect of salt concentration on production of polyunsaturated fatty acids in <Emphasis Type="Italic">Thraustochytrium aureum</Emphasis> ATCC 34304

This study attempted to characterize the effects of NaCl and MgSO₄ as the primary components of sea salt affecting the yields of production of polyunsaturated fatty acids (PUFAs) by Thraustochytrium aureum ATCC 34304. Reductions in the NaCl concentration of the culture medium suppressed the formation of palmitic acid (PA, C16: 0) but enhanced the production of PUFAs, which induced an increase of the concentration of docosahexaenoic acid (DHA, C22: 6) up to 46.65% from 44.26%. MgSO₄ revealed a similar, yet more highly significant, effect on the fatty acids profile than NaCl. The yields of PUFAs and DHA showed maximum values such as 67.10% and 49.47%, respectively, at the concentration of 10 g L⁻¹ for NaCl and 0 g L⁻¹ for MgSO₄. However, the quantities of mono-and diunsaturated fatty acids, oleic acid (OA, C18: 1) and linoleic acid (LA, C18: 2) at the same concentrations, were compared with those of normal culture medium. Additionally, it was investigated that the increase of culture temperature reduced PUFAs contents but the reductions were recovered by the removal of MgSO₄ form the culture medium, which showed that concentration of salts and culture temperature affected independently the production of PUFAs in T. aureum.     

Synthesis of Ultrafine and Spherical Barium Titanate Powders Using a Titania Nano-Sol

A novel synthetic method for the preparation of spherical, homogeneous, and ultrafine barium titanate (BaTiO₃) powders is described. An aqueous titania nano-sol was prepared by peptizing coarse aggregate of hydrous titania with nitric acid. BaTiO₃ powders could be synthesized through a simple reflux method using the titania nano-sol and barium hydroxide. As decreasing the titanium concentration, the particle size of the resulting spherical BaTiO₃ powder was increased from 40 to 130 nm and the porosity also increased. It was revealed that the smaller as-prepared BaTiO₃ powder was less porous and became more tetragonal with less intragranular pores after annealing. With this method, a highly tetragonal BaTiO₃ powder ( c / a ∼1.008) with a particle size of 120.0 nm was successfully prepared and would be very suitable for the thinner dielectrics in higher capacitance multilayer ceramic capacitors.     

Polymer property control in a continuous styrene polymerization reactor using model-on-demand predictive controller

The model-on-demand (MoD) framework was extended to the model predictive control (MPC) to design a multiple variable model-on-demand predictive controller (MoD-PC). This control algorithm was applied to the property control of polymer product in a continuous styrene polymerization reactor. For this purpose, a local auto-regressive exogenous input (ARX) model was constructed with a small portion of data located in the region of interest at every sample time. With this model an output prediction equation was formulated to calculate the optimal control input sequence. Jacket inlet temperature and conversion were chosen as the elements of regressor state vector in data searching step. Simulation studies were conducted by applying the MoD-PC to MIMO control problems associated with the continuous styrene polymerization reactor. The control performance of the MoD-PC was then compared with that of a nonlinear MPC based on the polynomial auto-regressive moving average (ARMA) model for disturbance rejection as well as for setpoint-tracking. As a result, the MoD-PC was found to be an effective strategy for the production of polymers with desired properties.     

Electroless copper electrolytes and its surface characteristics for semiconductor interconnects

In this research, to develop proper electroless copper electrolytes for semiconductor interconnects, the concentration and amount of additives are varied. Then, the stability, reactivity, deposition rate, leveling effect, and surface structure are examined. After a virgin makeup solution with suitable deposition characteristics is obtained, an electroless copper coating layer of high uniformity and adhesion strength was achieved using the stabilizer, catalyst, buffer, and pH adjuster as additives and surfactant on Ru diffusion barriers. Through annealing, resistance characteristics could be enhanced. Moreover, by measuring the cyclic voltammetry stripping and mixed potential of the electroless Cu electrolyte, its surface reactivity is electrochemically evaluated, and the result is in agreement with the deposition reaction. When the electrolyte developed in this study is applied on a trench pattern wafer with A/R 3.5 and a line width of 30 nm, it is possible to observe immaculate filling with improved leveling.     

Defect Control of the WC Hardmetal by Mixing Recycled WC Nano Powder and Tungsten Powder

Tungsten metal powder was added to recycled WC nano powder to control the macro and micro defects of WC hardmetal. The macro and micro defects caused by the excess carbon in the recycled WC powder were markedly removed after the addition of tungsten metal powder ranging from 2 to 6 wt%. The density and hardness of the WC hardmetals also increased due to the removal of defects after adding the tungsten metal powder. The density and hardness of WC hardmetals with the addition of W metal powder ranged from 8 to 12 wt% increased linearly as the W metal powder content increased due to the formation of a new (Co- and W-rich WC) composition. The surface morphology of the WC hardmetals was observed via field emission scanning electron microscopy, and a quantitative elemental analysis was conducted via X-ray fluorescence spectrometry and energy dispersive X-ray analysis. The density and hardness of the WC hardmetals were respectively measured using an analytical balance and a Vikers hardness tester. The effect on the defects in the recycled WC hardmetals through the addition of the tungsten metal powder was discussed in detail.     

Diversity analysis of Saccharomyces cerevisiae isolated from natural sources by multilocus sequence typing (MLST)

Food Science and Biotechnology - We used multilocus sequence typing (MLST) to analyze the diversity of natural isolates of Saccharomyces cerevisiae, the most important microorganism in alcoholic...     

Ex Vivo Live Full-Thickness Porcine Skin Model as a Versatile In Vitro Testing Method for Skin Barrier Research

Since the European Union (EU) announced their animal testing ban in 2013, all animal experiments related to cosmetics have been prohibited, creating a demand for alternatives to animal experiments for skin studies. Here, we investigated whether an ex vivo live porcine skin model can be employed to study the safety and skin barrier-improving effects of hydroxyacids widely used in cosmetics for keratolytic peels. Glycolic acid (1–10%), salicylic acid (0.2–2%), and lactobionic acid (1.2–12%) were used as representative substances for α-hydroxyacid (AHA), β-hydroxyacid (BHA), and polyhydroxyacid (PHA), respectively. When hydroxyacids were applied at high concentrations on the porcine skin every other day for 6 days, tissue viability was reduced to 50–80%, suggesting that the toxicity of cosmetic ingredients can be evaluated with this model. Based on tissue viability, the treatment scheme was changed to a single exposure for 20 min. The protective effects of a single exposure of hydroxyacids on skin barrier function were evaluated by examining rhodamine permeability and epidermal structural components of barrier function using immunohistochemistry (IHC) and immunofluorescence (IF) staining. Lactobionic acid (PHAs) improved skin barrier function most compared to other AHAs and BHAs. Most importantly, trans-epidermal water loss (TEWL), an important functional marker of skin barrier function, could be measured with this model, which confirmed the significant skin barrier-protective effects of PHAs. Collectively, we demonstrated that the ex vivo live full-thickness porcine skin model can be an excellent alternative to animal experiments for skin studies on the safety and efficacy of cosmetic ingredients.     

Antimicrobial resistance of Salmonella isolated from food animals: A review

Salmonella enterica is recognized as one of the most common causes of bacterial foodborne illness worldwide. The majority of Salmonella infections are attributed to consumption of contaminated food of animal origin such as eggs, chicken, pork, etc. Severe Salmonella infections often require antimicrobial therapy to aid in the elimination of the infection. A potential problem that has been developing for many decades is the development of antimicrobial resistance. There has been an increasing concern over the past 30 years regarding the worldwide emergence of multidrug-resistant phenotypes among Salmonella serotypes such as S. Typhimurium, S. Enteritidis and S. Newport. A special concern is the emergence of resistance to quinolones, fluoroquinolones or extended-spectrum cephalosporins such as ceftiofur and ceftriaxone. Recently, the occurrence of Salmonella isolates resistant to these antibiotics has increased. Therefore, continuous monitoring of its prevalence and resistance in the food supply is necessary because of the public health implications of a potential spread of resistant microorganisms. Furthermore, a holistic animal management approach such as stringent control of antimicrobial agents in the livestock industry, early clinical and microbiological diagnosis, appropriate treatment, and implementation of strict sanitary standards in the food industry are also needed to significantly reduce the overall burden of salmonellosis on human health.     

Poly-γ-Glutamic Acid Induces Apoptosis via Reduction of COX-2 Expression in TPA-Induced HT-29 Human Colorectal Cancer Cells

Poly-γ-glutamic acid (PGA) is one of the bioactive compounds found in cheonggukjang, a fast-fermented soybean paste widely utilized in Korean cooking. PGA is reported to have a number of beneficial health effects, and interestingly, it has been identified as a possible anti-cancer compound through its ability to promote apoptosis in cancer cells, although the precise molecular mechanisms remain unclear. Our findings demonstrate that PGA inhibits the pro-proliferative functions of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a known chemical carcinogen in HT-29 human colorectal cancer cells. This inhibition was accompanied by hallmark apoptotic phenotypes, including DNA fragmentation and the cleavage of poly (ADP-ribose) polymerase (PARP) and caspase 3. In addition, PGA treatment reduced the expression of genes known to be overexpressed in colorectal cancer cells, including cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS). Lastly, PGA promoted activation of 5'' adenosine monophosphate-activated protein (AMPK) in HT-29 cells. Taken together, our results suggest that PGA treatment enhances apoptosis in colorectal cancer cells, in part by modulating the activity of the COX-2 and AMPK signaling pathways. These anti-cancer functions of PGA make it a promising compound for future study.