Porous SiC and SiC/Cf Ceramic Microspheres Derived from Polyhydromethylsiloxane by Carbothermal Reduction

A simple and inexpensive method for the preparation of porous SiC microspheres is presented. Polysiloxane microspheres derived from polyhydromethylsiloxane (PHMS) cross-linked with divinylbenzene (DVB) were ceramized under conditions leading to the removal of oxygen from the material. The content of free carbon (Cf) in highly crystalline silicon carbide (SiC) particles can be controlled by using various proportions of DVB in the synthesis of the pre-ceramic material. The chemical structure of the ceramic microspheres was studied by elemental analysis for carbon and oxygen, 29Si MAS NMR, 13C MAS NMR, SEM/EDS, XRD and Raman spectroscopies, and their morphology by SEM, nitrogen adsorption and mercury intrusion porosimetries. The gaseous products of the thermal reduction processes formed during ceramization created a porous structure of the microspheres. In the SiC/Cf microspheres, meso/micro pores were formed, while in carbon-free SiC, microspheres macroporosity dominated

Application of <i>tris</i>-(4,7-Diphenyl-1,10 phenanthroline)ruthenium(II) Dichloride to Detection of Microorganisms in Pharmaceutical Products

tris-[(4,7-diphenyl-1,10-phenanthroline)ruthenium(II)] dichloride (Ru(DPP)3Cl2), a fluorescent sensor which is sensitive to the amount of oxygen in the sample, was applied using the fluorescent optical respirometry (FOR) technique. The oxygen in the samples quenches the fluorescence. The fluorescence intensity depends on the metabolic rate of the viable microorganisms. The effect of DMSO and plant extracts on bacteria was determined by FOR. It was shown that the MIC values obtained by FOR were consistent with the results of the MIC determinations using the method of serial dilutions; at the same time, the effects of concentrations lower than the growth-inhibitory concentrations on microbial cells were demonstrated. The FOR method enables the detection of multiplying bacteria in sterile and non-sterile pharmaceutical preparations in real time, which significantly shortens the time required to obtain results and allows the introduction of repair processes in the production. This method also allows for quick, unambiguous detection and the counting of the viable cells of aerobic microorganisms in non-sterile pharmaceuticals

Quillaja saponaria Saponins with Potential to Enhance the Effectiveness of Disinfection Processes in the Beverage Industry

This study examines the in vitro effect of Quillaja saponaria extracts on Asaia spp. planktonic cells and biofilms, in comparison and combination with two disinfectants: peracetic acid and N-ethyl-N,N-dimethylhexadecylammonium bromide. The growth of six bacterial strains was evaluated spectrophotometrically. Biofilm eradication was determined using the plate count method and luminometry. The planktonic cells were characterized by relatively high resistance to peracetic acid and higher sensitivity to N-ethylo-N,N-dimethylohexadecylioamonium bromide. In almost all the tested strains, growth was inhibited by 0.125% (v/v) peracetic acid and 0.0313% (w/v) quaternary ammonium compound. However, combinations of cell pretreatment using saponin and peracetic acid action were the most efficient against both planktonic and biofilm cells. The minimum inhibitory concentrations for peracetic acid were 4–8 times lower than those for bacterial strains without preliminary saponin action. Eradication of Asaia spp. biofilms reduced the number of living cells by 4–5 logarithmic units. These results demonstrate the synergetic action of saponin extract and disinfectant, and could be useful in the development of industrial strategies against Asaia spp. biofilms

The Usefulness of Vanin-1 and Periostin as Markers of an Active Autoimmune Process or Renal Fibrosis in Children with IgA Nephropathy and IgA Vasculitis with Nephritis—A Pilot Study

This study aimed to evaluate the usefulness of vanin-1 and periostin in urine as markers of the autoimmune process in kidneys and renal fibrosis in IgA nephropathy (IgAN) and IgA vasculitis with nephritis (IgAVN). From a group of 194 patients from the Department of Pediatrics and Nephrology, who were included in the Polish Pediatric Registry of IgAN and IgAVN, we qualified 51 patients (20 with IgAN and 31 with IgAVN) between the ages of 3 and 17, diagnosed based on kidney biopsy, for inclusion in the study. All of the patients received glucocorticosteroids, immunosuppressive drugs, or renoprotective therapy. The control group consisted of 18 healthy individuals. The concentration of vanin was significantly higher in the IgAN and IgAVN groups than in the control group. The concentration of vanin/creatinine correlates positively with the level of IgA and negatively with the serum level of C3 at the end of the observation. Urinary vanin-1 concentration may be useful as a marker of the active autoimmune process in IgAN and IgAVN in children, but the study needs confirmation on a larger group of children, along with evaluation of the dynamics of this marker. Urinary periostin is not a good marker for children with IgAN and IgAVN, especially in stage 1 and 2 CKD

Usefulness of urinary collagen IV excretion for predicting the severity of Henoch-Schönlein nephropathy children

The aim of the study was to evaluate the usefulness of urinary collagen IV (Col IV) excretion for predicting the severity of autoimmune renal inflammation in children with HSN (Henoch-Schönlein nephritis). Material and methods: We studied 26 children, in whom HSN was diagnosed based on kidney biopsy. In all patients, urinalysis was performed and 24-hour urinary protein excretion was measured at the onset of the disease. All kidney biopsies were also scored using the Oxford classification: M – mesangial hypercellularity score (M0 absent, M1 present); E – presence of endocapillary proliferation (E0 absent, E1 present), S – segmental glomerulosclerosis/adhesion (S0 absent, S1 present), T – tubular atrophy/interstitial fibrosis (T0 ≤ 25%, T1 26-50%, T2 > 50%). The MEST score was calculated as the sum of M + E + S + T. Results: Urinary Col IV level was significantly higher in the study group than in control group. Urinary Col IV level was insignificantly higher in group A (nephrotic proteinuria) compared to the B (non-nephrotic proteinuria) and C (without proteinuria).We found no significant differences in the age at the disease onset, severity of proteinuria, and Col IV between groups 1 (S0, T0) and 2.(S1,T1/T2). The MEST score was significantly higher in group 2 than group 1. Conclusions: Urinary Col IV excretion in children with HSN may be related to the lesions severity by the Oxford classification but seems to be associated with the mean value (the MEST score). In younger children, a more aggressive disease course is observed, and thus earlier and more aggressive treatment should be considered in this group

Antibacterial Electroconductive Composite Coating of Cotton Fabric

Graphene oxide (GO) was deposited on a cotton fabric and then thermally reduced to reduced graphene oxide (rGO) with the assistance of L-ascorbic acid. The GO reduction imparted electrical conductivity to the fabric and allowed for electrochemical deposition of Ag° particles using cyclic voltammetry. Only the Ag°/rGO composite coating imparted antibacterial properties to the fabric against Escherichia coli and Staphylococcus aureus. Ag°/rGO-modified fibers were free of bacterial film, and bacterial growth inhibition zones around the material specimens were found. Moreover, Ag°/rGO-modified fabric became superhydrophobic with WCA of 161°

Self-Restructuring of Polyhydromethylsiloxanes by the Hydride Transfer Process: A New Approach to the Cross-Linking of Polysiloxanes and to the Fabrication of Thin Polysiloxane Coatings

The branching and cross-linking of siloxane polymers are important processes in silicone technology. A new type of such a process has been developed, which is a self-restructuring of linear polyhydromethylsiloxane (PHMS). This process involves the reorganization of the PHMS to form a highly branched siloxane polymer or finally a cross-linked siloxane network. It occurs through the transfer of a hydride ion between silicon atoms catalyzed by tris(pentafluoromethyl)borane. Its advantage over existing branching and cross-linking reactions is that it runs at room temperature without a low-molecular-weight cross-linker in the absence of water, silanol groups, or other protic compounds and it does not use metal catalysts. The study of this process was carried out in toluene solution. Its course was followed by 1H NMR, 29Si NMR and FTIR, SEC, and gas chromatography. A general mechanism of this new self-restructuring process supported by quantum calculations is proposed. It has been shown that a linear PHMS self-restructured to a highly branched polymer can serve as a pure methylsiloxane film precursor

Reaction of Silyl Hydrides with Tetrabutoxygermanium in the Presence of B(C₆F₅)₃: Difference between Silicon and Germanium Chemistries and Easy Route to GeH₄

Dehydrocarbonative condensation reaction between alkoxysilanes and hydrosilanes catalyzed by tris­(pentafluorophenyl)­borane has been widely used for the formation of siloxane bonds. Our attempt to extend this chemistry to the preparation of Ge–O–Si bonds produced an unexpected outcome. The reaction of Ge­(OBu)₄ with PhMe₂SiH in the presence of a catalytic amount of B­(C₆F₅)₃ at room temperature proceeded smoothly with the complete consumption of reactants and formation of GeH₄ and PhMe₂SiOBu in high yields. For the first time we have achieved selective exchange of functional groups between Ge–OR and Si–H. The discovered reaction features simple reaction conditions and can be used to prepare GeH₄ in situ from easily available and safe substrates