Bacteriostatic Effects of Apatite-Covered Ag/AgBr/TiO2 Nanocomposite in the Dark: Anomaly in Bacterial Motility

In this paper, we report a unique property of inactivating Gram-positive/negative bacteria in the dark via apatite-covered Ag/AgBr/TiO2 nanocomposites (AAAT). We demonstrate that the inactivation mechanism is bacteriostatic based on the cellular integrity and motility of bacteria, low toxicity and high durability of AAAT. From straight observations, the catalytic loading affects the bacterial replication and cell envelope as well as inducing an anomaly in bacterial motility (continuous rotation) for both types of bacteria. Both simulation and experimental analyses suggest that the anomaly could be due to posterior intracellular signals rather than purely mechanical effects (e.g., size enlargement and motility retardation). Provoked by chemomechanical stimuli, these signals increase the frequency of flagellar tumbling and eventually entangle the bacteria

Spin-Forbidden Formation of Amide Molecules in the Interstellar Medium

In this study, two-state spin-forbidden mechanisms are proposed for the barrierless formation of amide isomers in the C2H5NO family of molecules. This family belongs to the first level of complexity among the molecules with peptide bond that are precursors to proteins, which are building blocks of life, and therefore are highly relevant to astrochemistry and astrobiology. Our density functional theory study demonstrates the significance of spin-forbidden pathways in the formation of acetamide (CH3CONH2), N-methyl-formamide (CH3NHCHO), and acetimidic acid (CH3COHNH) from the acetaldehyde, imidogen, formamide, and methylene reactants. Considering the rate constants of analogous reactions in the interstellar medium (ISM), we anticipate that the detected abundances of acetamide and N-methyl-formamide in the Sagittarius B2 North region can be rationalized by the suggested formation pathways. The proposed mechanism also predicts the synthesis of acetimidic acid, motivating future observational efforts to identify this molecule in the ISM

Second Order Saddle Points Dictate the Products of Electrocyclic Reactions

The conventional understanding of chemical reactions, primarily focused on one-dimensional minimum energy pathways, has been expanded in recent years to include phenomena like second order saddle points or bifurcations. In this study, we explore these intricacies within the context of electrocyclizations and present a novel approach that moves beyond the traditional view of activation barriers, revealing that second order saddle points are crucial in dictating the competition between disrotatory and conrotatory pathways. Our findings suggest opportunities to manipulate the competition between conrotatory and disrotatory pathways through geometric constraints, fundamentally altering the connectivity of the potential energy surface. Through the development of a minimal model Hamiltonian, we illustrate the generality of our findings and highlight the importance of the multi-reference nature of states near the second order saddle point. This study emphasizes the necessity of multi-reference methods and the need to conduct higher-dimensional explorations for competing pathways. It opens new avenues for systematic control of selectivity in electrocyclic reactions and offers a rich perspective on the complex interplay of steric considerations and electronic correlations

Derivation of Morse Potential Function

The Morse potential is widely used in chemistry to describe interatomic interactions. However, there is no explicit derivation for this empirical potential from physically meaningful atomic quan- tities. We show that the Morse potential can be derived from a simple atomic screened charge model, which accounts for the shielded nuclear charge by the electron density and exponentially de- cays with distance. The bond dissociation energy of a diatomic molecule is obtained by combining the quantum mechanical covalent and classical electrostatic interactions. The revealed connec- tions between the parameters of the Morse potential, the Pauling bond order and electronegativity bridge the gap between the classical and quantum mechanical descriptions of chemical bonds. The proposed derivation and interpretation of the Morse potential in terms of atomic quantities such as electron-nuclear attraction energy and orbital exponents will be valuable in helping students to form a simple picture of chemical bond

A Review to Water Treatment Methods in Developed Countries (Case study: USA)

In today world water and water resources are considered as one of the most important properties. The main challenges for societies are to prepare food, water and energy. Among these it is somehow easier to provide food, because there are many ways to prepare it, also energy because of finding new resources, and it is only water that can make troubles for societies if there is no resource left. So planning for economizing the use of it and protection of available resources are of primary priorities. On the other hand occurrence of several droughts and increasing population growth, make the need for healthful drinking water. The water purification, better use of it in industry, water need in agricultural, the technological advances to use industrial, such as analytical methods in water purification and reducing the costs is inevitable. Some examples are chromatographic columns, resins, ion exchangers for softening, and reducing the hardness of water, and other processes such as chlorination, fluoridation, filtering and precipitation via advanced methods by using effective disinfection, advanced industrial methods and use of microprocessors to control the purification. In this connection purification processes in advanced countries are investigated such as United States. The advantages and disadvantages of mentioned methods are reported from different aspects. The result of such studies can provide us to use the new experiences in the world to use water Treatment technologies in Iran in order to prepare healthful drinking water and at the same time to reduce waste of time and expenses

A Review to Water Treatment Methods in Developed Countries

In today world water and water resources are considered as one of the most important properties. The main challenges for societies are to prepare food, water and energy. Among these it is somehow easier to provide food, because there are many ways to prepare it, also energy because of finding new resources, and it is only water that can make troubles for societies if there is no resource left. So planning for economizing the use of it and protection of available resources are of primary priorities. On the other hand occurrence of several droughts and increasing population growth, make the need for healthful drinking water. The water purification, better use of it in industry, water need in agricultural, the technological advances to use industrial, such as analytical methods in water purification and reducing the costs is inevitable. Some examples are chromatographic columns, resins, ion exchangers for softening, and reducing the hardness of water, and other processes such as chlorination, fluoridation, filtering and precipitation via advanced methods by using effective disinfection, advanced industrial methods and use of microprocessors to control the purification. In this connection purification processes in advanced countries are investigated such as United States. The advantages and disadvantages of mentioned methods are reported from different aspects. The result of such studies can provide us to use the new experiences in the world to use water Treatment technologies in Iran in order to prepare healthful drinking water and at the same time to reduce waste of time and expenses

Probiotic mixture of Lactobacillus helveticus R0052 and Bifido bacterium longum R0175 attenuates hippocampal apoptosis induced by lipopolysaccharide in rats

Abstract In recent years, the beneficial impact of targeted gut microbiota manipulation in various neurological disorders has become more evident. Therefore, probiotics have been considered as a promising approach to modulate brain gene expression and neuronal pathways even in some neurodegenerative diseases. The purpose of this study was to determine the effect of probiotic biotherapy with combination of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 on the expression levels of proteins critical to neuronal apoptosis in hippocampus of lipopolysaccharide (LPS)-exposed rats. Four groups of animals (Control, LPS, Probiotic + LPS, and Probiotic) were treated with maltodextrin (placebo) or probiotic (109 CFU/ml/rat) for 2 weeks by gavage. On the 15th day, a single intraperitoneal dose of saline or LPS (1 mg/kg) was injected and 4 h later, protein assessment was performed by western blotting in hippocampal tissues. LPS significantly increased the Bax, Bax/Bcl-2 ratio, and cleaved caspase- 3 expression along with decreased the Bcl-2 and procaspase-3 protein levels. However, probiotic pretreatment (L. helveticusM R0052 + B. longum R0175) significantly downregulated the Bax and Bax/Bcl-2 ratio accompanied with upregulated Bcl-2 expression. Prophylactic treatment with these bacteria also attenuated LPS-induced caspase-3 activation by remarkably increasing the expression of procaspase-3 while reducing the level of cleaved caspase-3 in target tissues. Our data indicate that probiotic formulation (L. helveticus R0052 + B. longum R0175) alleviated hippocampal apoptosis induced by LPS in rats via the gut-brain axis and suggest that this probiotic could play a beneficial role in some neurodegenerative conditions. Keywords Gut microbiota manipulation . Probiotic . Apoptosis . Lipopolysaccharide . Neurodegenerative disease . Gut-brain axi

The Effects of Probiotic Formulation Pretreatment (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) on a Lipopolysaccharide Rat Model.

OBJECTIVE: The role of gut microbiota in the pathogenesis of several neurodegenerative disorders, including Alzheimer's disease (AD), via the gut-brain axis has recently been demonstrated; hence, modification of the intestinal microbiota composition by probiotic biotherapy could be a therapeutic target for these conditions. The aim of this study was to assess the effects of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) on inflammatory and memory processes in lipopolysaccharide (LPS)-induced rats, one of the animal models used in peripherally induced neuroinflammation and neurodegeneration. METHODS: Rats were randomly divided into four groups (Control, LPS, Probiotic + LPS, and Probiotic). All experimental groups were orally administrated maltodextrin (placebo) or probiotic (109 CFU/ml/rat) for 14 consecutive days and then were injected with saline or LPS (1 mg/kg, intraperitoneally [i.p.], single dose) 20 hours later. Memory retention ability and systemic and neuroinflammatory markers were assessed 4 hours after the injections. RESULTS: Systemic exposure to LPS resulted in significant elevation of both the circulating and hippocampal levels of proinflammatory cytokines, which decreased remarkably following probiotic pretreatment. Oral bacteriotherapy with a combination of L. helveticus R0052 and B. longum R0175 also attenuated the decremental effect of LPS on memory through brain-derived neurotrophic factor (BDNF) expression at the molecular level; however, this effect was not significant in the passive avoidance test at the behavioral level. CONCLUSIONS: These results suggest that the management of gut microbiota with this probiotic formulation could be a promising intervention to improve neuroinflammation-associated disorders such as AD