Properties of biodegradable blend films based on fish myofibrillar protein and polyvinyl alcohol as influenced by blend composition and pH level

Effects of the ratios of fish myofibrillar protein (FMP) from bigeye snapper (Priacanthus tayenus) to polyvinyl alcohol (PVA) (FMP:PVA; 10:0, 8:2, 6:4, 5:5, 4:6, 2:8, 0:10) and pH levels (3 and 11) on the properties of resulting films were investigated. Both tensile strength (TS) and elongation at break (EAB) of films increased with increasing PVA content (p < 0.05). When PVA was incorporated up to 40%, films prepared at pH 11 had the higher TS than did those prepared at pH 3 (p < 0.05). However, as PVA content was greater than 40%, films prepared at pH 3 exhibited the higher TS than did those prepared at pH 11 (p < 0.05). Water vapor permeability (WVP) of the films prepared at pH 3 increased when PVA content increased up to 40% and decreased with further increases in PVA content (p < 0.05). PVA films had the higher TS, EAB and WVP than did FMP films and FMP/PVA blend films prepared at both pHs. Films exhibited the increased L∗ and a∗ values but decreased b∗ value with increasing PVA content at both pHs. Films prepared at pH 11 showed higher b∗ value than did those prepared at pH 3 when PVA content was greater than 40% (p < 0.05). FMP/PVA blend films exhibited the negligible transmission to the UV light. At pH 3, light transmission of the films increased as PVA content increased (p < 0.05). At all FMP/PVA ratios, films prepared at pH 11 were less transparent than those prepared at pH 3 (p < 0.05). Therefore, blend composition and pH level influenced the properties of FMP/PVA blend films.     

Biodiesel Synthesis from Palm Fatty Acid Distillate Using Tungstophosphoric Acid Supported on Cesium-Containing Niobia

Tungstophosphoric acid supported on cesium-containing niobia (TPA/Cs _x /Nb₂O₅, x = 1.0–2.5) catalysts were prepared by a two-step impregnation method, and their physico-chemical properties were investigated. The initial studies on the esterification of oleic acid with methanol revealed that TPA/Cs ratio affected the acidity as well as the activity of the catalysts. Among the catalysts tested, TPA/Cs_1.0/Nb₂O₅ exhibited the best performance. In addition, the efficiency of TPA/Cs_1.0/Nb₂O₅ for biodiesel synthesis from palm fatty acid distillate (PFAD), a by-product from palm oil industry, was demonstrated, and the reaction parameters were also evaluated. Over 90% yield of FAME was achieved, and the properties of the biodiesel obtained from PFAD met the standard requirements for biodiesel fuel. However, deactivation of the catalysts was observed, possibly due to structural transformation or organic residues blocking the active sites.     

Identification of auxotrophic mutants of the yeast Kluyveromyces marxianus by non‐homologous end joining‐mediated integrative transformation with genes from Saccharomyces cerevisiae

The isolation and application of auxotrophic mutants for gene manipulations, such as genetic transformation, mating selection and tetrad analysis, form the basis of yeast genetics. For the development of these genetic methods in the thermotolerant fermentative yeast Kluyveromyces marxianus, we isolated a series of auxotrophic mutants with defects in amino acid or nucleic acid metabolism. To identify the mutated genes, linear DNA fragments of nutrient biosynthetic pathway genes were amplified from Saccharomyces cerevisiae chromosomal DNA and used to directly transform the K. marxianus auxotrophic mutants by random integration into chromosomes through non‐homologous end joining (NHEJ). The appearance of transformant colonies indicated that the specific S. cerevisiae gene complemented the K. marxianus mutant. Using this interspecific complementation approach with linear PCR‐amplified DNA, we identified auxotrophic mutations of ADE2, ADE5,7, ADE6, HIS2, HIS3, HIS4, HIS5, HIS6, HIS7, LYS1, LYS2, LYS4, LYS9, LEU1, LEU2, MET2, MET6, MET17, TRP3, TRP4 and TRP5 without the labour‐intensive requirement of plasmid construction. Mating, sporulation and tetrad analysis techniques for K. marxianus were also established. With the identified auxotrophic mutant strains and S. cerevisiae genes as selective markers, NHEJ‐mediated integrative transformation with PCR‐amplified DNA is an attractive system for facilitating genetic analyses in the yeast K. marxianus. Copyright © 2013 John Wiley & Sons, Ltd.     

Investigation of spring-go phenomenon using finite element method

Bending is an application used in the sheet metal forming processes in many industries. One of the main problems of the bending process is the occurrence of spring-back/spring-go. Past research has investigated the spring-back problem. However, the spring-go problem was rarely investigated. In this study, the spring-go phenomenon was investigated using the finite element method (FEM) on the V-bending process. The FEM simulation results clearly and theoretically clarified the spring-go phenomenon on the material flow analysis and stress distribution. The comparison between the spring-back and spring-go phenomena was also clarified.     

Influences of degree of hydrolysis and molecular weight of poly(vinyl alcohol) (PVA) on properties of fish myofibrillar protein/PVA blend films

Biodegradable blend films based on fish myofibrillar protein (FMP) and poly(vinyl alcohol) (PVA) were prepared and characterized. PVA with different degrees of hydrolysis (DH) and molecular weights (MW) had the impact on properties of FMP/PVA (1:1, w/w) blend film. The blend films with higher MW of PVA were more tensile resistant, as indicated by the greater tensile strength (TS) and elongation at break (EAB), while the films with PVA of lower DH were more flexible. The blend film with PVA-BP26 (DH: 86–98% mol; MW: 124,000–130,000 g/mol) exhibited the greatest tensile performance and the lowest water vapor permeability (p < 0.05), compared with other films. SEM and FTIR results revealed that FMP and PVA were compatible and their intermolecular interaction was enhanced, providing the blend film with desirable properties. Therefore, incorporation of PVA with appropriated DH and MW could improve the properties of the FMP-based film.     

Advanced HiCTE flip chip packaging of 90-nm Cu/Low-K chips: Underfill,novel terminal pad structures,and processing optimization

Packaging of 90-nm Cu/Low-K chips presents a serious challenge, which requires an advanced ceramic flip chip solution. Finer Cu interconnects are expected to interact differently with the current underfill-to-die passivation stack-up structures used for Al or previous Cu technology nodes especially in system level applications. Furthermore, the more porous and brittle-proned advanced Low-K (K<3) dielectrics present additional process incompatibility problems such as stress-induced crackings and delaminations. These reliability issues in various stress-relieving passivation structures and materials (i.e., Benzocyclobutene (BCB) and single versus double SiOxNy passivations) have not been extensively studied. This study analyzes the effect of the eight metal layer 90-nm Cu/Low-K flip chip devices through designed experiments using two relatively different underfill materials, standard terminal pad and novel passivation structures, and JEDEC Level-3 reliability stressings: temperature cycling (TC), highly accelerated stress testing (HAST), and high-temperature storage (HTS). Black Diamond Low-K and HiCTE ceramic substrates are employed for the large package form factor. The active Si uses eutectic stencil-pasted SnPb bump and BGA balls with Ti/Ni-V/Al-Cu reflectory thin film-deposited under bump metallurgy (UBM). It is found that the double passivation pad structures are less susceptible to reliability damage for various types of underfills, although a single passivation with BCB coating combined with an optimal underfill can also yield a similar favorable result. The metallurgical effect of delamination cracking, HiCTE flip chip and stress-relieving passivation structures, and the underfill interface failure mode mechanism are examined by functional testing, chemical deprocessings, scanning acoustic microscope (SAM), and scanning electron microscope (SEM)/energy-dispersive x-ray (EDX). The presented results are significant for the development of flip chip packaging technologies for future advanced Cu/Low-K generations.     

Devise of a W serpentine shape tube heat exchanger in a hard chromium electroplating process

In a hard chromium electroplating process, a heat exchanger is employed to remove the heat produced from the high current intensity in an electroplating bath.Normally, a conventional U shape heat exchanger is installed in the bath, but it provides low heat removal.Thus, this study designs a novel W serpentine shape heat exchanger with identical heat transfer area to the conventional one for increasing heat removal performance.The performance of the heat exchange is tested with various flow velocities in a cross-section in range of 1.6 to 2.4 m·s~(-1).Mathematical models of this process have been formulated in order to simulate and evaluate the heat exchanger performance.The results show that the developed models give a good prediction of the plating solution and cooling water temperature, and the novel heat exchanger provides better results at any flow velocity.In addition, the W serpentine shape heat exchanger has been implemented in a real hard chromium electroplating plant.Actual data collected have shown that the new design gives higher heat removal performance compared with the U shape heat exchanger with identical heat transfer area; it removes more heat out of the process than the conventional one of about 23%.