Microstructure and Electro-Physical Properties of Sn-3.0Ag-0.5Cu Nanocomposite Solder Reinforced with Ni Nanoparticles in the Melting-Solidification Temperature Range

The electrical conductivity of nanocomposite Sn-3.0Ag-0.5Cu alloys with two different weight percentages of Ni nanoparticles (1.0 and 2.0 wt.%) was measured over a wide temperature range. The samples were produced using a cold pressing method: Sn-3.0Ag-0.5Cu powder and Ni nanopowder were mechanically mixed and pressed into 8 mm diameter rods. Ni nanoparticles were synthesized via a chemical reduction method and characterized by a core/shell structure. Temperature dependencies of the electrical conductivity revealed a hysteresis between the heating and cooling curves in a wide temperature range above the melting temperature. This fact is connected with structure transformations accompanied by a dissolution of Ni nanoparticles, which should be retarded due to an oxide/hydroxide shell on the surface of the nanoparticles. A microstructure analysis of the samples in the solid state showed a fine distribution of intermetallic compounds in the Sn-based matrix. The Ni atoms substituted for Cu atoms in the Cu₆Sn₅ compound forming a (Cu,Ni)₆Sn₅ phase.     

Dietary fiber,fructooligosaccharides, and physicochemical properties of homogenized aqueous suspensions of yacon (Smallanthus sonchifolius)

Yacon roots are a promising source of inulin­type fructans (35 g/100 g dry matter) with a total amount of dietary fiber of about 45 g/100 g dry matter. The polydispersity of the particle size distribution of yacon aqueous suspension was reduced with increasing the degree of homogenization due to two phenomena: aggregation of particles, and disruption of large particles. Non­homogenized yacon suspensions exhibited large cell clusters that were disrupted into small cell clusters, single cells, and aggregates. The most concentrated suspension exhibited mainly aggregates.The volume fraction of the suspensions decreased significantly with increasing the degree of homogenization. This was attributed to a denser packing of small particles and aggregates in between large particles thus allowing the water within the structure to be released.Yacon suspensions exhibited high elastic modulus (750 Pa) at low water insoluble solids content (0.9% WIS). Additional results suggested that inulin­type fructans contributed to the elastic properties of yacon suspensions.The yacon suspensions studied in this work can be considered as semi­concentrated suspensions, i.e. the plot elastic modulus of the suspensions versus concentration exhibited a region immediately after the transition region. Particle interactions seem to be of great importance in this region in the particular case of yacon suspension since the elastic modulus (G′) reached 750 Pa at low water insoluble solids content (< 1%).     

New Circulating Circular RNAs with Diagnostic and Prognostic Potential in Advanced Colorectal Cancer

Circular RNAs (circRNAs) are a group of special endogenous long non-coding RNAs which are highly stable in the circulation, and, thus, more suitable as new biomarkers of colorectal cancer (CRC). The aim of our study was to explore the plasma expression levels of four circRNAs: has_circ_0001445, hsa_circ_0003028, hsa_circ_0007915 and hsa_circ_0008717 in patients with CRC and to evaluate their associations with clinicopathological characteristics and the clinical outcome of the patients. CircRNAs were extracted from patients’ plasma obtained prior to chemotherapy. Their expression levels were measured by qPCR and calculated applying the 2^−ΔΔCt method. The levels of all four circRNAs were significantly increased in the plasma of CRC patients. At the optimal cut-off values hsa_circ_0001445 and hsa_circ_0007915 in plasma could significantly distinguish between patients with or without metastatic CRC with 92.56% sensitivity and 42.86% specificity, and with 86.07% sensitivity and 57.14% specificity, respectively. The mean overall survival (OS) of patients with high/intermediate expression of hsa_circ_0001445 was 30 months, significantly higher in comparison with the mean OS of the patients with low expression—20 months (log-rank test, p = 0.034). In multivariate Cox regression analysis, the low levels of hsa_circ_0001445 were also associated with shorter survival (HR = 1.59, 95% CI: 1.02–2.47, p = 0.040). A prognostic significance of hsa_circ_0001445 for patients with metastatic CRC was established.     

Antibacterial poly(vinyl alcohol) film containing silver nanoparticles: Preparation and characterization

The importance of antibacterial materials for biomedical applications is growing nowadays. The presented article deals with the characterization of structural, mechanical and thermal properties and of antibacterial polymeric films based on polyvinyl alcohol (PVA) and silver nitrate, which can find their applicability in wound dressing components and protective coating. The methods of transmission electron microscopy, UV–vis and XRD spectroscopy, optical microscopy, differential scanning calorimetry, stress–strain analysis, and agar diffusion test were used to characterize the polymer films prepared. The results showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus already at the lowest addition level of silver nitrate. An improvement of mechanical properties (Young's modulus) was also noticed due to a modification of PVA with silver nitrate up to 1 wt. % of silver content. Furthermore, the results show a strong effect of the thermal history of the sample preparation on the degree of silver‐ion reduction and formation of nanoparticles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

THE REACTION OF WESTERN U.S. OIL SHALE KEROGEN WITH PHENOL

ABSTRACT

Phenol reacts with Western U.S. oil shale kerogen. The acid–catalyzed reaction gives crude products which incorporate large amounts of phenol. The toluene soluble portion of the crude products was shown by ¹H, ¹³C-NMR, FIMS, and LVHR/mass spectroscopy to consist mainly of condensed phenols. However, about 15% of the carbon in this fraction is derived from kerogen fragments. These results contrast markedly with those found for other systems reacting under similar conditions. To further explore the scope of this reaction, model compounds were allowed to react with acidified phenol. Hydrocarbons were unreactive. Certain aryl ethers and substituted phenols were very reactive. Mineral matter was also found to catalyze the reaction of phenol with the toluenesu l fonic acid catalyst. These data indicate that substituted phenols and/or aryl ethers are probably important cross-linking centers for kerogen. Long straight chain aliphatic groups appear to also be present in kerogen.     

Sphingolipid Catabolism and Glycerophospholipid Levels Are Altered in Erythrocytes and Plasma from Multiple Sclerosis Patients

Multiple sclerosis (MS) is an autoimmune, inflammatory, degenerative disease of the central nervous system. Changes in lipid metabolism have been suggested to play important roles in MS pathophysiology and progression. In this work we analyzed the lipid composition and sphingolipid-catabolizing enzymes in erythrocytes and plasma from MS patients and healthy controls. We observed reduction of sphingomyelin (SM) and elevation of its products—ceramide (CER) and shingosine (SPH). These changes were supported by the detected up-regulation of the activity of acid sphingomyelinase (ASM) in MS plasma and alkaline ceramidase (ALCER) in erythrocytes from MS patients. In addition, Western blot analysis showed elevated expression of ASM, but not of ALCER. We also compared the ratios between saturated (SAT), unsaturated (UNSAT) and polyunsaturated fatty acids and suggest, based on the significant differences observed for this ratio, that the UNSAT/SAT values could serve as a marker distinguishing erythrocytes and plasma of MS from controls. In conclusion, the application of lipid analysis in the medical practice would contribute to definition of more precise diagnosis, analysis of disease progression, and evaluation of therapeutic strategies. Based on the molecular changes of blood lipids in neurodegenerative pathologies, including MS, clinical lipidomic analytical approaches could become a promising contemporary tool for personalized medicine.     

Water-soluble temperature-responsive poly(vinyl alcohol-co-vinyl acetal)s

Summary In order to obtain novel temperature-responsive copolymers, poly(vinyl alcohol) (PVA) was chemically modified by introducing cyclic acetal functionalities in the polymer chain. The acetalization reaction was carried out with acetaldehyde in water The degree of acetalization was controlled in the range 10–25% by the initial aldehyde concentration. The copolymers obtained were characterized by 1D (¹H, ¹³C, DEPT) and 2D (COSY) NMR techniques as well as by viscometry. The thermo-responsive properties were evaluated by measuring the cloud point temperature (T_cp) of the aqueous copolymer solutions.     

THE REACTION OF WESTERN U.S. OIL SHALE KEROGEN WITH PHENOL

Phenol reacts with Western U.S. oil shale kerogen. The acid-catalyzed reaction gives crude products which incorporate large amounts of phenol. The toluene soluble portion of the crude products was shown by ¹H, ¹³C-NMR, FIMS, and LVHR/mass spectroscopy to consist mainly of condensed phenols. However, about 15% of the carbon in this fraction is derived from kerogen fragments. These results contrast markedly with those found for other systems reacting under similar conditions. To further explore the scope of this reaction, model compounds were allowed to react with acidified phenol. Hydrocarbons were unreactive. Certain aryl ethers and substituted phenols were very reactive. Mineral matter was also found to catalyze the reaction of phenol with the toluenesu l fonic acid catalyst. These data indicate that substituted phenols and/or aryl ethers are probably important cross-linking centers for kerogen. Long straight chain aliphatic groups appear to also be present in kerogen.     

Subjective evaluation of terry fabrics handle

Based on a survey among specialists, the impact of criteria such as thickness, bulkiness, smoothness, stiffness, extensibility and elasticity on the handle of terry fabrics is evaluated and ranked. A methodology was developed to determine the weight coefficient of the factors involved in the evaluation. A relation was determined providing a connection between the examined factors and the handle rated on the Kawabata scale. A manual evaluation of terry fabric with different mass per unit area, structural features and finishing treatments was performed. Two methods were used – by ranking and by assigning a numerical score (from 0 to 5). The opinion of the evaluators has proven consistency, as the ranking of the samples, regardless of the method, was the same. The obtained results will be used to create a complex evaluation of terry fabrics handle.