Synthesis, Characterization, and Antifungal Activity of Silver Nanoparticles Embedded in Pullulan Matrices

Steady developments made in nanotechnology-based products have facilitated new perspectives for combating drug-resistant fungi. Silver nanoparticles represent one of the most attractive nanomaterials in biomedicine due to their exclusive optical, electromagnetic, and catalytic properties and antifungal potency compared with other metal nanoparticles. Most studies show that the physicochemical parameters affecting the antifungal potential of AgNPs include the shape, size, surface charge, and concentration and colloidal state. For the present study, pullulan (P) and its oxidized counterpart (PO) have been selected as matrices for the silver nanoparticles’ generation and stabilization (AgNPs). The TEMPO (2,2,6,6-tetramethylpiperidin-1-yl radical)–sodium hypochlorite–sodium bromide system was used for the C6 selective oxidation of pullulan in order to introduce negatively charged carboxylic groups in its structure. The structure and morphology of the synthesized AgNPs were analyzed using FTIR and EDX. The main objective of this study was to elucidate the antifungal activity of AgNPs on the clinical yeasts isolates and compare the performance of AgNPs with the conventional antifungals. In this study, different concentrations of AgNPs were tested to examine antifungal activity on various clinical isolates.

Study on the Preparation of Nanocellulose Powder and Its Formation Mechanism

Nanocellulose is a kind of cellulose based nano material with fantastic properties and numerous potential applications. However, due to the fact that nanocellulose exhibits colloidal properties when its concentration is high, the drying of nanocellulose has always been an urgent problem to be solved. To address this problem, the precipitation and drying mechanism of cellulose nanocrystal (CNC), one of the most common types of nanocellulose, was studied in this paper. The CNC was precipitated from the aqueous suspension by salting out to avoid the CNC colloidal state when concentrated in water. The obtained CNC precipitation with a small amount of water and the actively added electrolyte was dehydrated and purified by solvent displacement with volatile organic. Then CNC powder can be taken shape by drying the mixture of CNC and organic solvent with different drying methods. The mechanism of CNC precipitation from aqueous suspension and CNC powder formation from volatile organic solvent was studied. After comprehensive consideration, a method for preparing re-dispersible CNC powder was established, and the properties of this powder were studied, that provided a solution for the industrial preparation and application of nanocellulose.

Study of homeostasis of the body of pigs with the addition of asparaginates to feed

The article presents the results of studying the effect of different doses of trace-elements combined with L-aspartic acid (asparaginase) on the overall homeostasis of the body of piglets. Traceelements play the main part in the composition of many organic compounds that maintain the stability of the buffer system of the colloidal state of the liquid and the osmotic pressure in the body. Scientists have proven that metal compounds in the inorganic form, in the composition of feed, are little absorbed by the body. Moreover, the increase of their doses in order to improve the level of assimilation in the body of animals, most often, causes the development of toxicosis. Therefore, the aim of the work was to study the effect of different amounts of trace-elements (Zn, Fe, Cu, Mn, Co) in the organic form combined with L-aspartic acid on the overall homeostasis of the body of piglets. In order to achieve this goal, we conducted an experiment on large white pigs in the conditions of a pig farm in the Saratov region. We have proved that in order to normalize the overall homeostasis, as well as to increase the productive indicators of fattening piglets, it is recommended to use a mineral complex based on L-aspartic acid in the amount of 10% of the daily norm of requirements for inorganic trace elements. This topic has not been sufficiently studied in the literature to date.

INVESTIGATION OF RHEOLOGICAL PROPERTIES OF HYDROXYAPATITE AND FLUORAPATITE IN COLLOIDAL STATE

В статье обсуждается возможность практического применения суспензии гидроксиапатита и фторапатита в качестве компонентов лекарственных средств, фармацевтических композиций и биоматериалов. С использованием физикохимических методов анализа оценены их вязкость, плотность и степень дисперсности. Определены концентрационные интервалы, в которых исследуемые системы обладают свойствами, необходимыми для создания фармацевтических композиций и биоматериалов. Биологическая активность апатитов во многом зависит от степени дисперсности и проявляется тем больше, чем меньше размер их частиц, а полученные в данной работе наночастицы гидроксиапатита и фторапатита в суспензиях имеют размер частиц порядка менее 100 нм, и, следовательно, реологические свойства у них проявятся наиболее полно. The article discusses the possibility of practical application of a suspension of hydroxyapatite and fluorapatite as components of medicines, pharmaceutical compositions, and biomaterials. Their viscosity, density and degree of dispersion were estimated by using the physical and chemical analysis methods. The concentration intervals in which the studied systems have the properties necessary for creating pharmaceutical compositions and biomaterials are determined. The biological activity of apatites largely depends on the degree of dispersion and manifests itself the more, the smaller the size of their particles, and the obtained in this work nanoparticles of hydroxyapatite and fluorapatite in suspensions have a particle size of the order of less than 100 nm, and, consequently, their rheological properties will be most fully manifested.

2. Milkiness, muddiness, and inkiness

‘Milkiness, muddiness, and inkiness’ discusses the phenomena of ‘muddiness’ and ‘inkiness’, which are both examples of ‘colloids’—the fundamental class of soft matter constituted by dispersing very small particles of solid matter in a liquid environment. The colloidal state provided the final evidence that atoms existed. Michael Faraday gave a well-known lecture on the ‘Brownian Motion’ and he also researched gold colloids which show how small particles disperse. Albert Einstein came up with a theory of thermal noise, and Charles Perrin carried out a famous experiment in 1908 on this topic. Both Einstein and Perrin showed that colloidal particles can do everything that molecules do, but at a thousand times the size, and equally more slowly.

The nanostructured or colloidal state is the fifth aggregate state of substance

The article shows that the basis of nanotechnology is the discovery in the early 20th century of a colloidal (ultradispersed) or nanostructured state of substance, in which the dimensions of physical and/or chemical dispersed phases distributed in the dispersion medium of a substance have dimensions less than 100 nanometers, at least in one coordinate. Since any substance, regardless of its chemical composition, can be converted to a nanostructured state, this state should be considered the fifth aggregate state of substance, along with the solid, liquid, gaseous and plasma states. The transfer of substances and / or materials to the nanostructured state can be carried out by numerous different methods, which defines a wide range of nanotechnologies. And since the nanostructured state is a new aggregate state of substance, it has unique physical and chemical properties compared to the usual solid substance.

Preparation and Properties of Wood Tar-based Rejuvenated Asphalt

In order to explore the applicability of the rejuvenated asphalt with wood tar as the main raw material, the orthogonal test was used to determine the optimal ratio of wood tar-based rejuvenator. The physical properties, rheological properties and components of matrix asphalt, aged asphalt, wood tar-based rejuvenated asphalt and commercial RA-102# rejuvenated asphalt were tested and compared. The results show that the optimal ratio of wood tar-based rejuvenator is 15wt% wood tar, 0.3wt% biomass fiber, 5wt% plasticizer, 0.3wt% compatibilizer, and 1wt% stabilizer of the mass of aged asphalt. Wood tar-based rejuvenator can restore the physical properties of the aged asphalt to meet the specification requirements. The synergistic effect of biomass fiber and plasticizer make the wood tar-based rejuvenated asphalt has good resistance to accumulated permanent deformation, but its low-temperature cracking resistance needs to be further improved. During the rejuvenation process of aged asphalt, the colloidal state changes from gel-state to sol-state, characterizing that the viscosity of asphalt decreased and the fluidity increased. Wood tar-based rejuvenator can react with aged asphalt to weaken the vibration strength of carbonyl and sulfoxide groups, so as to realize the recovery of service performance. Wood tar-based rejuvenator has better environmental protection and applicability, which is worthy of further study and promotion.

Autoperforation of Two-Dimensional Materials to Generate Colloidal State Machines Capable of Locomotion

A central ambition of the robotics field has been to increasingly miniaturize such systems, with perhaps the ultimate achievement being the synthetic microbe or cell sized machine. To this end,...