The Effect of Surfactants on the Aggregate Stability of the Aqueous Suspensions of Metal Carbonates.

онатів купруму та ніколу, карбонатів мангану і кобальту. Для регулювання агрегативної стабільності були використані промислові ПАР: неіоногенна TRITON X-100, катіонна HYAMINE 1622 та аніонна ATLAS G-3300. Одержані результати обговорюють у рамках моделі редиспергування порошків у рідких середовищах. Показано, що вплив ПАР на редиспергувальну здатність середовища залежить від дисперсності порошків, а саме зі збільшенням їхньої дисперсності (зменшенням розмірів частинок) вплив ПАР зменшується порівняно з водою. Адсорбція іоногенних ПАР ATLAS G-3300 та HYAMINE 1622 має суттєвий вплив на збереження досягнутого ступеня редиспергування порошків, а вплив неіоногенної ПАР TRITON X-100 на агрегативну стабільність суспензій усіх порошків є незначним і неоднозначним. The effect of surfactants on aggregation-disaggregation processes during the preparation of the suspensions of basic copper and nickel carbonates and manganese and cobalt carbonates was investigated. Industrial surfactants such as non-ionogenic TRITON X-100, cationic HYAMINE 1622 and anionic ATLAS G-3300 were used to regulate the aggregate stability of the aqueous suspensions. Obtained results are discussed within the framework of the model of the powder re-dispersion in liquid media. It was shown that the effect of surfactants on the re-dispersion ability of the medium depends on the powder dispersity degree, namely that the increase of the powder dispersity (smaller particle size) lowers the effect of surfactants compared to water. The absorption of the ionogenic surfactants ATLAS G-3300 and HYAMINE 1622 has a substantial effect on the preservation of the achieved powder re-dispersion degree. The effect of the non-ionogenic surfactant TRITON X-100 on the aggregate stability of the suspensions of all powders is minor and varied

Phonon Raman spectra of colloidal CdTe nanocrystals: effect of size, non-stoichiometry and ligand exchange

Resonant Raman study reveals the noticeable effect of the ligand exchange on the nanocrystal (NC) surface onto the phonon spectra of colloidal CdTe NC of different size and composition. The oleic acid ligand exchange for pyridine ones was found to change noticeably the position and width of the longitudinal optical (LO) phonon mode, as well as its intensity ratio to overtones. The broad shoulder above the LO peak frequency was enhanced and sharpened after pyridine treatment, as well as with decreasing NC size. The low-frequency mode around 100 cm-1 which is commonly related with the disorder-activated acoustical phonons appears in smaller NCs but is not enhanced after pyridine treatment. Surprisingly, the feature at low-frequency shoulder of the LO peak, commonly assigned to the surface optical phonon mode, was not sensitive to ligand exchange and concomitant close packing of the NCs. An increased structural disorder on the NC surface, strain and modified electron-phonon coupling is discussed as the possible reason of the observed changes in the phonon spectrum of ligand-exchanged CdTe NCs

Biological processes, properties and molecular wiring diagrams of candidate low-penetrance breast cancer susceptibility genes

Background: Recent advances in whole-genome association studies (WGASs) for human cancer risk are beginning to provide the part lists of low-penetrance susceptibility genes. However, statistical analysis in these studies is complicated by the vast number of genetic variants examined and the weak effects observed, as a result of which constraints must be incorporated into the study design and analytical approach. In this scenario, biological attributes beyond the adjusted statistics generally receive little attention and, more importantly, the fundamental biological characteristics of low-penetrance susceptibility genes have yet to be determined. Methods: We applied an integrative approach for identifying candidate low-penetrance breast cancer susceptibility genes, their characteristics and molecular networks through the analysis of diverse sources of biological evidence. Results: First, examination of the distribution of Gene Ontology terms in ordered WGAS results identified asymmetrical distribution of Cell Communication and Cell Death processes linked to risk. Second, analysis of 11 different types of molecular or functional relationships in genomic and proteomic data sets defined the 'omic' properties of candidate genes: i/ differential expression in tumors relative to normal tissue; ii/ somatic genomic copy number changes correlating with gene expression levels; iii/ differentially expressed across age at diagnosis; and iv/ expression changes after BRCA1 perturbation. Finally, network modeling of the effects of variants on germline gene expression showed higher connectivity than expected by chance between novel candidates and with known susceptibility genes, which supports functional relationships and provides mechanistic hypotheses of risk. Conclusion: This study proposes that cell communication and cell death are major biological processes perturbed in risk of breast cancer conferred by low-penetrance variants, and defines the common omic properties, molecular interactions and possible functional effects of candidate genes and proteins