Physiological and Immunological Changes Associated with Oral Microbiota When Using a Thermoplastic Retainer

Background: The study examined the oral microbiota, physiological and immunological changes in patients using thermoplastic retainers during three months of use. Methods: The study included several steps. Firstly, 10 swabs were collected from the buccal and palatal surfaces of the teeth of the patients, approximately 2 mL of saliva was collected from the same patients and 2 mL of saliva was collected from 10 healthy people to measure the pH and secretory IgA level. This was followed by the isolation and identfication of the bacterial isolates in the patient samples. Then, isolate susceptibility toward chlorhexidine (CHX) and their adhesion ability to thermoplastic retainer surfaces was measured. In addition to that the study estimated the numbers of Lactobacillus and Streptooccus mutans colonies during three months and finally, a comparsion of pH acidity and IgA level between the patients and healthy people was performed. The results showed the predominant bacteria during the three months were Lactobacillus spp. and Streptococcus spp. followed by different rates of other bacteria. Raoultella ornithinolytica showed more resistance to CHX while Lactobacillus spp. showed more sensitivity. Streptococcus mutans colony levels were higher than Lactobacillus spp. colonies during the three months, also S. mutans had the highest value in adherence to retainer thermoplastic. Finally, pH acidity showed a highly significant difference (p ≤ 0.05) in the third month, like IgA levels (p ≤ 0.05). Conclusions: According to the results obtained from the current study, the researchers noted that the thermoplastic retainers helped change the oral cavity environment.     

Kinetic,isotherm, and mechanism investigations of the removal of nitrate and nitrite from water by the synthesized hydrotalcite Mg–Al

Research on Chemical Intermediates - The objective of this work is to test the effectiveness of hydrotalcite as an adsorbent for the retention of nitrate and nitrite ions and to study the influence...     

Plasma-Assisted Reaction Chemical Ionization for Elemental Mass Spectrometry of Organohalogens

We present plasma-assisted reaction chemical ionization (PARCI) for elemental analysis of halogens in organic compounds. Organohalogens are broken down to simple halogen-containing molecules (e.g., HBr) in a helium microwave-induced plasma followed by negative mode chemical ionization (CI) in the afterglow region. The reagent ions for CI originate from penning ionization of gases (e.g., N₂) introduced into the afterglow region. The performance of PARCI-mass spectrometry (MS) is evaluated using flow injection analyses of organobromines, demonstrating 5–8 times better sensitivities compared with inductively coupled plasma MS. We show that compound-dependent sensitivities in PARCI-MS mainly arise from sample introduction biases.

含吡啶的大环席夫碱锰(Ⅱ)配合物:合成、表征及抗菌性质(英文)

在Mn髤模板作用下,2,6-diacetylpyridine(DAP)及合适链状胺化合物通过[1+1]环缩合反应,合成了3个大环席夫碱配合物,并进行了红外、元素分析、质谱及电导率等表征及研究。测得了配合物[MnL1(CH3CN)](ClO4)2的晶体结构,中心离子呈现出稍微扭曲的五角锥配位构型。研究了配合物对S.aureus(ATCC 6633),B.cereus(ATCC 7064),C.xerosis(ATCC 373)(gram-positive bacterial strains),E.coli(PTCC 10009),K.pneuomoniae(MTCC 109),and P.vulgaris(lio)(gram-negative bacterial strains)的抗菌活性。结果显示[MnL3](ClO4)2抗菌活性明显优于[MnL1(CH3CN)](ClO4)2and[MnL2](ClO4)2。在25℃条件下0.1 mol·L-1 KCl溶液中,通过电位计量法测定了化合物的质子化常数。     

Mild,four-component synthesis of 6-amino-4-aryl-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles catalyzed by titanium dioxide nano-sized particles

A convenient and efficient solvent-free procedure is described for preparation of 6-amino-4-aryl-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles by four-component reaction of hydrazine hydrate, ethyl acetoacetate, aryl aldehyde, and malononitrile in the presence of a catalytic amount of titanium dioxide nano-sized particles. Short reaction times, high yields under ambient conditions, simple reaction, clean work-up, and reusability of the nano heterogeneous catalyst are the advantages of this method.     

First-principle investigation of XSrH3 (X = K and Rb) perovskite-type hydrides for hydrogen storage

Hydrogen can be utilized as an energy source; therefore, hydrogen storage has received the most appealing examination interest in recent years. The investigations of hydrogen storage applications center fundamentally around the examination of hydrogen capacity abilities of recently presented compounds. XSrH₃ (X = K and Rb) compounds have been examined by density functional theory (DFT) calculations to uncover their different characteristics, as well as hydrogen capacity properties, for the first time. Studied compounds are optimized in the cubic phase, and optimized lattice constants are obtained as 4.77 and 4.99 Å for KSrH₃ and RbSrH₃, respectively. These hydrides have shown negative values of formation enthalpies as they are stable thermodynamically. XSrH₃ might be used in hydrogen storage applications because of high gravimetric hydrogen storage densities, which are 2.33 and 1.71 wt% for KSrH₃ and RbSrH₃, respectively. Moreover, electronic properties confirm the semiconductor nature of these compounds having indirect band gaps of values 1.41 and 1.23 eV for KSrH₃ and RbSrH₃, respectively. In addition, mechanical properties from elastic constants such as Young modulus and Pugh's ratio, also have been investigated, and these compounds were found to satisfy born stability conditions. Furthermore, Pugh's ratio and Cauchy pressure show that these hydrides have a brittle nature. Furthermore, thermodynamic properties such as entropy and Debye temperature have been examined using the quasiharmonic Debye model for different temperatures and pressures.     

Exo/endo stereocontrolled synthesis of spiroindoloindolizidines by using classical and microwave conditions via the 1,3-dipolar cycloaddition reaction

Using both classical reflux and microwave-mediated conditions, a series of new spiroindoloindolizidines was synthesized by multicomponent 1,3-dipolar cycloaddition of azomethine ylides in unprecedented exo/endo stereocontrolled. Both conditions easily afforded two identical and separable exo/endo diastereomeric ratios of cycloadducts. However, the ratio of two diastereomeric products obtained from conventional conditions was reversed in all examined cases when the reactions were explored under microwave-mediated conditions. As expected, utilizing the microwave-assisted conditions produced higher yields and reaction rates compared to classical conditions. The structure and exact stereochemistry of synthesized cycloadducts were determined by applying various 2D-NMR spectroscopic techniques and single-crystal X-ray diffraction. Finally, the mechanism of the reaction has been briefly investigated by using density functional theory (DFT) calculations.     

4-Oxobenzo[d]1,2,3-triazin-pyridinium-phenylacetamide derivatives as new anti-Alzheimer agents: design,synthesis, in vitro evaluation,molecular modeling,and molecular dynamic study

Structural Chemistry - A new series of 4-oxobenzo[d]1,2,3-triazin-pyridinium-phenylacetamide hybrids 8a–p was designed, synthesized, and screened as the potential cholinesterase inhibitors...     

Brownian motion and thermophoresis effects on unsteady stagnation point flow of Eyring-Powell nanofluid: a Galerkin approach

This article concerns the analysis of an unsteady stagnation point flow of Eyring-Powell nanofluid over a stretching sheet. The influence of thermophoresis and Brownian motion is also considered in transport equations. The nonlinear ODE set is obtained from the governing nonlinear equations via suitable transformations. The numerical experiments are performed using the Galerkin scheme. A tabular form comparison analysis of outcomes attained via the Galerkin approach and numerical scheme (RK-4) is available to show the credibility of the Galerkin method. The numerical exploration is carried out for various governing parameters, namely, Brownian motion, steadiness, thermophoresis, stretching ratio, velocity slip, concentration slip, thermal slip, and fluid parameters, and Hartmann, Prandtl and Schmidt numbers. The velocity of fluid enhances with an increase in fluid and magnetic parameters for the case of opposing, but the behavior is reversed for assisting cases. The Brownian motion and thermophoresis parameters cause an increase in temperature for both cases (assisting and opposing). The Brownian motion parameter provides a drop-in concentration while an increase is noticed for the thermophoresis parameter. All the outcomes and the behavior of emerging parameters are illustrated graphically. The comparison analysis and graphical plots endorse the appropriateness of the Galerkin method. It is concluded that said method could be extended to other problems of a complex nature.     

Magnetic solid-phase extraction using Schiff base ligand supported on magnetic nanoparticles as sorbent combined with dispersive liquid-liquid microextraction for the extraction of phenols from water samples

ABSTRACT

In this work, the magnetic sorbent was developed by covalent binding of a Schiff base ligand, N,N’-bis(3-salicyliden aminopropyl)amine (salpr), on the surface of silica coated magnetic nanoparticles (Salpr@SCMNPs). The core-shell nanoparticle was applied for the magnetic solid-phase extraction (MSPE) combined with dispersive liquid-liquid microextraction (DLLME) of phenolic compounds from water samples prior to gas chromatography-flame ionisation detector (GC?FID). Characterisation of the Salpr@SCMNPs was performed with different physicochemical methods such as Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Variables affecting the performance of both extraction steps such as pH of the water sample, the sorbent amount, the desorption conditions, the extraction time; and extraction solvent were studied. Under the optimised conditions, the analytical performances were determined with a linear range of 0.01–100 ng mL^?1 and a limit of detection at 0.003–0.02 ng mL^?1 for all of the analytes studied. The intra-day (n = 5) and inter-day (n = 3) relative standard deviations (RSD%) of three replicates were each demonstrated in the range of 6.9–8.9% and 7.3–10.1%, respectively. The proposed method was executed for the analysis of real water samples, whereby recoveries in the range of 92.9–99.0% and RSD% lower than 6.1% were attained.