Water Pain Research Articles

Evaluation of the pathogenicity of Pseudomonas aeruginosa isolates to strains of mice under stressful conditions

Pseudomonas aeruginosa (Pa) is an opportunistic pathogen that threatens the health, especially in immunocompromised individuals. Pseudomonas aeruginosa survives everywhere, including in a shuttle of spaceflights. Survival and starvation of Pa in water probably increase or decrease the degree of pathogenicity or virulence, but it is not well discovered. To promote our understanding of the mechanisms of Pa long-term survival in water, investigations on survival kinetics and its pathogenicity to mice are under investigation in our laboratory. Data has shown that under starvation conditions in water, Pa can lead to (i) survival for over 15 years in water; (ii) distinct changes in colony morphology, including loss of pigmentation. This study also aimed to determine the pathogenicity of clinical and environmental isolates of Pa in water under starved conditions. We hypothesized that the starvation of Pa isolates in water results in different survival curves, morphological, that may enhance pathogenicity in mice. Mice infected with starved isolates showed a lesser death rate than non-starved isolates. This project compared the susceptibility of BALB/c, C57BL/6J, and DBA/2 J in lung infection. Our data shows the vulnerability of DBA/2J was high compared to BALB/c or C57BL/6J. Hindlimb-unloading increased the death rate in DBA/2J compared to BALB/c strains. Lung infection of different Pa isolates shows a differential death rate, with the highest death rate caused by non-starved isolates in mice. Overall, long-term starvation of Pa isolates exits may lead to a reduced mortality rate of mice.

Synthesis of samarium orthoferrite-based perovskite nanoparticles as a turn-on fluorescent probe for trace level detection of picric acid

Picric acid (2,4,6-trinitrophenol, PA) is a common constituent of many powerful explosives, thus, development of the chemical probes for trace level detection of PA is a crucial current challenge in both public security and environmental protection. In this work, the applicability of the new perovskite-type oxide SmFeO3 nanoparticles as an inorganic fluorescence turn-on probe for the selective and sensitive recognition of PA in organic and aqueous media was investigated. The synthesis of nanoparticles SmFeO3 was carried out using the surfactant-assisted templating approach which proceeds through the sol–gel process based on nonionic surfactant Triton X-100. The synthesized SmFeO3 nanoparticles exhibited strong solvent-dependent emission at 330 nm wavelength with absorption maxima at 225 nm. Among the tested explosives, the probe showed the highest sensitivity and selectivity for detecting PA in water and water/acetonitrile mixture. The response time for detecting PA was less than 5 s. The limits of detection for PA in acetonitrile and water/acetonitrile mixture were 2.1 µM and 1.1 µM, respectively. Furthermore, to investigate the nature of the fluorescence turn-on sensing mechanism, the experimental data of the dynamic light scattering (DLS) technique and zeta-potential were used. Both techniques confirmed the aggregation-induced emission (AIE) mechanism for detection of PA with the synthesized turn-on probe. The results of the present work will have a considerable impact on the development and applications of a new class of inorganic fluorescence turn-on probes for the detection of PA.

Poly(acrylamide/vinylsulfonic acid) hydrogel for invertase immobilization.

Poly (acrylamide/vinylsulfonic acid) PA/VSA and poly (acrylamide) PA hydrogels were prepared by free radical polymerization in the presence of a crosslinker, to be used as a support for the invertase enzyme. Spectrophotometric, thermal analysis methods, swelling, and diffusion experiments were used for the characterization of hydrogels. SEM images show that the hydrogels have a smooth, homogeneous, highly porous and spongy morphology. The swelling of PA/VSA was higher than that of PA in water. The diffusion of water within the hydrogel was found to be non-Fickian. Invertase was immobilized onto PA and PA/VSA (immobilized invertases named PA-I and PA/VSA-I, respectively). The optimum pH values were found to be; 5.0, 3.0, and 3.0 for free invertase, PA-I, and PA/VSA-I, respectively. The optimum temperature values were 40°C, 50°C, and 60°C for free invertase, PA-I and PA/VSA-I respectively. Michaelis Constant, Km ; for free invertase and PA-I and PA/VSA-I were found to be 11.80, 21.40, and 18.42 mM, respectively. Maximum reaction rate; Vmax value for free invertase and PA-I and PA/VSA-I were found to be 7.46 μmol min-1 , 5.91 μmol min-1 , and 6.35 μmol min-1 , respectively. PA/VSA-I showed excellent thermal, operational, storage, and pH stability.

Self-assembly induced hydrogelation approach as novel means of selective and visual sensing toward picric acid

Picric acid is a kind of dangerous and toxic nitroaromatic explosive chemicals and causes great concern in safety, health and environment issues. However, the visual and selective sensing of picric acid in pure water is still a challenge in recent years. In this work, two novel isomeric sugar-based derivatives denoted as NGs (NG1 and NG2) with different terminal groups (pyridyl segments) have been designed and synthesized. We demonstrate the preparation of picric acid assisted supramolecular hydrogels driven by hydrogen bonding interaction, which endows the visual and direct recognition for picric acid via fast and selective gelation approach without expensive equipment. The binding mechanism of NGs with PA both in solutions and gels and the isomeric effect on the gelation properties are studied in detail by several techniques. At last, NG2 based test strips are also developed to detect tiny amount of PA in water in a contact mode.

ADSORPTION MECHANISM AND STRUCTURAL INVESTIGATION OF DOPED C60 FULLERENES WİTH PENTYLAMINE

Interaction mechanisms of doped fullerenes and various types of molecules have been paid increasing attention. In this research, absorption mechanism, structural and electronic properties, natural bond orbital analysis between pentylamine (pa) and doped (Si or Al) C 60 fullerenes were investigated by quantum mechanical calculations. Bond order and binding energy results suggest that a chemisorption occur between nitrogen atom of pa and silicon/aluminum atoms of fullerene cages, examined complexes yielded with higher binding energy in water media and the system of AlC 59 …pa in water was found as having the highest binding energy.

Aqueous or solvent based surface modification: The influence of the combination solvent – organic functional group on the surface characteristics of titanium dioxide grafted with organophosphonic acids

To alter the versatility of interactions at its surface, TiO2 is modified with organophosphonic acids (PA). A thorough understanding of the role of all synthesis conditions is necessary to achieve controlled functionalization. This study reports on the effect of using water, toluene and their mixtures when performing the modification of TiO2 with PA. Sorption and calorimetry measurements of surface interactions with various probing species clearly indicate that, by grafting PA in water, clear differences appear in the distribution of organic groups on the surface. Also the functional group of the PA determines the impact of using water as solvent. Modification in toluene results in a higher modification degree for propylphosphonic acid (3PA), as the solvent–solute interaction may hinder the grafting with phenylphosphonic acid (PhPA) in toluene. Water is preferred as solvent for PhPA modification as stabilizing π—OH interactions enhance surface grafting overcoming the competitive interaction of water at the surface as observed with 3PA. By using water in toluene mixtures for the functionalization of TiO2 with 3PA, the degree of functionalization is higher than when only water or toluene is used. Furthermore, adding small amounts of water leads to the formation of titanium propylphosphonates, next to surface grafting.

Yield stress measurements and microstructure of colloidal kaolin powders clusterized and dispersed in different liquids

Rheological measurements of four colloidal kaolin powders dispersed in water, paraffinic oil and liquid rubber have been done at solid concentration θ ( V S/ V L) in the range 8–33%. In quasi-static conditions the yield stress τ° values were derived. An S-shaped relationship between τ° and θ exists, that allows to evaluate the percolation threshold θ c values. In water θ c ranges between 29% and 33%, while it is between 17% and 21% in oil and in liquid rubber. In water the microstructure units, i.e. the primary clusters among kaolin crystallites, are denser and bigger than the ones in the two other liquids. Furthermore, in quasi-static condition, the aqueous microstructure units have less tendency to cling together to form a network that can span all over the liquid phase. The different kaolin dispersions at θ equal to 22% are characterized by yield stress ranging between 7.5 Pa and 59 Pa in water, 66–250 Pa in oil and 230–770 Pa in liquid rubber. It has been found that for any kaolin types the ∂log τ°/∂ θ evaluated near to the percolation threshold is a conservative parameter of the three different liquids. These results are useful to design colloidal dispersions with selected microstructure.