Expression Of Hydrophobicity Research Articles

Alkyl-terminated PEG suppressors for copper electroplating and their hydrophilic and hydrophobic properties

This study explores the structure-activity relationship of copper electroplating suppressors, with a focus on alkyl-terminated polyethylene glycols (PEGs), to better understand their efficacy in electronic interconnect fabrication. Electrochemical analysis demonstrated that an increase in the molecular weight of PEG suppressors significantly raises the electrochemical polarization overpotential during copper electrodeposition. Additionally, alkyl terminal capping was observed to amplify this polarization effect, with the extent of overpotential increase directly correlating with the alkyl chain length. However, the advantageous impact of molecular weight on overpotential diminishes at higher molecular weights. In contrast to the electrochemical results, through-hole electroplating experiments revealed that a suppressor with a molecular weight of 1 k and butyl termination exhibits superior through-hole throwing power. Further analysis indicated that a greater proportion of alkyl functional groups within the suppressor's molecular chain enhances uniform electroplating capabilities. The study also suggests that measuring contact angles, as an expression of hydrophobicity, could provide a more efficient and precise method for evaluating suppressor performance.

THE SURFACE CHARACTER OF Staphylococcus aureus ISOLATED FROM SUBCLINICAL MASTITIS OF DAIRY COW SUPPORTING ADHERENCE TO UDDER EPITHELIAL CELL

Staphylococcus aureus (S. aureus) is one among pathogen bacteria that caused mastitis in dairycow in Indonesia. Its ability to initiate infection depends on the surface character of the bacteria. Thesurface character of S. aureus is determined by the corelation of red blood cell hemagglutination activity,hydrophobicity, production of protein A, and bacterial adherence to the mammary epithelial cells of thehost. This research was designed to characterize the surface of S.aureus, which correlates to bacterialadherence. Four isolates of S. aureus were taken from subclinical mastitis milk of dairy farm in Malang,East Java. The surface character of S.aureus was determined by performing the red blood cellhemagglutination test using the dairy cow erythrocyte suspension with concentration of 0.5%, 1%, and2%. The hydrophobicity expression was determined by Salt Aggregation Test (SAT) method using theAmmonium Sulfate suspension with concentration of 1.2 M, 1.6 M, 2.0 M, 2.4M, and 3.2 M. Serum softagar (SSA) test was used to indicate the production of protein A; Ability of adhesion was done byadhering the S.aureus, which were already labelled by Fluorescent Ichtiocyanate (FITC) to themammary epithelial cell of post-calving mice. Result of this this research showed that the surfacecharacters of S.aureus, which correlates to the adherence, comprise of erythrocytes hemagglutinationability, hydrophobicity, and protein A production. Isolates of S.aureus, which is hydrophobic, possesshaemagglutinine, and protein A were able to adhere to mammary epithelial cell with higher quantity

A novel method for identifying hydrophobicity on fungal surfaces

Fungal surface hydrophobicity has many ecological functions and water contact angles measurement is a direct and simple approach for its characterization. The objective of this study was to evaluate if in-vitro growth conditions coupled with versatile image analysis allows for more accurate fungal contact angle measurements. Fungal cultures were grown on agar slide media and contact angles were measured utilizing a modified microscope and digital camera setup. Advanced imaging software was adopted for contact angle determination. Contact angles were observed in hydrophobic, hydrophilic and a newly created chronoamphiphilic class containing fungi taxa with changing surface hydrophobicity. Previous methods are unable to detect slight changes in hydrophobicity, which provide vital information of hydrophobicity expression patterns. Our method allows for easy and efficient characterization of hydrophobicity, minimizing disturbance to cultures and quantifying subtle variation in hydrophobicity.

Influence of cell surface hydrophobicity on attachment ofCandida albicansto extracellular matrix proteins

Cell surface hydrophobicity expression by Candida albicans facilitates a diffuse binding distribution of yeast cells to host tissues ex vivo. One possibility for the receptor site responsible for the binding pattern of hydrophobic cells is the extracellular matrix (ECM). In this study, we evaluated the interaction of hydrophobic and hydrophilic C. albicans with ECM proteins immobilized onto wells of microtitre tissue. Culture plates, and the ability of ECM proteins to block the binding of hydrophobic cells to splenic tissue ex vivo. Hydrophobic C. albicans bound in greater numbers than hydrophilic cells to the immobilized proteins, particularly fibrinogen, fibronectin, collagen type IV and laminin. Similar results were obtained regardless of C. albicans strains or of growth medium. Collagen and fibronectin blocked the binding of hydrophobic cells to the white pulp but not to the marginal zones in splenic tissues when tested with the ex vivo assay. These results suggests that the diffuse binding pattern of hydrophobic cells in the ex vivo assay may be due to their enhanced ability over hydrophilic cells to bind to ECM proteins, particularly fibronectin and collagen type IV.

Solvent deuteration enhancement of hydrophobicity: DSC study of the inverse temperature transition of elastin-based polypeptides

As previously shown, the polypentapeptide of elastin, (Val{sup 1}-Pro{sup 2}-Gly{sup 3}-Val{sup 4}-Gly{sup 5}){sub n} or simply poly(VPGVG), undergoes an inverse temperature transition which is seen macroscopically as a phase separation with a dense viscoelastic phase of about 60% water, 40% peptide by weight and which is characterized molecularly by increase in intra- and intermolecular order as evidenced by formation of specific hydrophobic contacts. Furthermore, from an extensive study of polypentapeptides of the composition poly(f{sub x}(VPGXG), f{sub v}(VPGVG)), where f{sub x} + f{sub v} = 1 and X is any of the amino acid residues with apolar (hydrophobic) side chains, it has been shown that the temperature of the transition decreases and the heat of the transition increases with increased hydrophobicity. In the present paper differential scanning calorimetry has been utilized to determine the effect of D{sub 2}O on the temperature and heats of the inverse temperature transitions for poly(VPGVG), poly(IPGVG), poly(LPGVG), and poly(VPAVG) and in the latter case in the presence of 0.5 and 1.0 N NaCl and of 1,2, and 3 M urea. In all cases, the effect of D{sub 2}O as compared to H{sub 2}O is to lower the transition temperature about 2 C and to increase themore » heat of the transition about 10%, and this occurs also in the presence of NaCl, which itself lowers the temperature and increases the heat, and in the presence of urea, which itself raises the temperature and decreases the heat of the transition. It is concluded that the effect of replacement of H{sub 2}O by D{sub 2}O by D{sub 2}O in these polypeptides is to effect a small but consistent increase in the expression of hydrophobicity.« less