Shape-dependent antibacterial activity of silver nanoparticles on Escherichia.coli and Enterococcus.faecium bacterium

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Silver nanoparticles (AgNPs) have been shown to exhibit strong antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria including antibiotic resistant strains. The antibacterial activity of AgNPs against Escherichia coli and Streptococcus mutans (S. Mutans) has been reported and found to be size dependent. This study aims to compare the bactericidal effect of different shaped AgNPs (spherical and truncated octahedral) against E.coli and E.faecium. The antimicrobial activity of a range of concentrations (50, 100, 1000μg/ml) was determined over 24 hours using both optical density and viable counts. Truncated octahedral AgNPs (AgNoct) were found to be more active when compared with spherical AgNPs (AgNS). The difference in shape resulted in differences in efficacy which may be due to the higher surface area of AgNOct compared to AgNS, and differences in active facets and surface energies, with AgNPs having a bacteriostatic effect and AgNOct is being bactericidal after 4 hours. The results suggest that AgNPs can be used as effective growth inhibitors in different microorganisms, rendering them applicable tovarious medical devices and antimicrobial control systems

Electrically Small Particles for Energy Harvesting in the Infrared and Microwave Regimes

Harnessing energy from clean and sustainable resources is of crucial importance to our planet. Several attempts through different technologies have been pursued to achieve efficient and sustainable energy production systems. However, having systems with a high energy harvesting efficiency and at the same time low energy production cost are challenging with the existing technologies. In this research, several novel structures based on electrically small particles are proposed for harvesting the microwave and infrared energy efficiently. First, a proof of concept demonstrates a metamaterial unit cell's ability to harness the ambient electromagnetic energy. A split-ring resonator (SRR) representing the metamaterial unit cell is designed at a microwave frequency (5.8 GHz) and then fabricated by using printed circuit board technology to prove this concept. A bow-tie antenna, operating at the above frequency, is also designed to show the power efficiency improvement achieved by utilizing the SRR. More than 37% of power efficiency is achieved using SRRs-based structure compared to the 13% of the bow-tie antenna. A new efficiency term is also proposed to take into account the size reduction and efficiency advancement resulting from SRR structures. To this end, two comparable arrays of SRRs and bow-tie antennas are made. Power efficiency of 63.2% and 15.3% for the SRRs and bow-tie arrays, respectively, are achieved. Another structure composed of an ensemble of electrically small resonators for harvesting microwave energy is presented. A flower-like structure composed of four electrically small SRRs arranged in a cruciate pattern, each with a maximum dimension of less than ʎo/10, is shown to achieve more than 43% microwave-to-alternating current (AC) conversion efficiency at 5.67 GHz. Even- and odd-mode currents are realized in the proposed harvester to improve the efficiency and concurrently reduce the dielectric loss in the substrate. An experimental validation is conducted to prove the harvesting capability. To extend the work to operate at the far-infrared regime, a novel structure based on electrically small resonators is proposed for harvesting the infrared energy and yielding more than 80% harvesting efficiency. The dispersion effects of the dielectric and conductor materials of the resonators are taken into account by applying the Drude model. A new scheme to channel the infrared waves from an array of SRRs is proposed, whereby a wide-bandwidth collector is utilized by employing this new channeling concept. With the same pattern of the flower-like harvester operating in microwave regime, a new structure composed of electrically small SRRs, each of whose greatest length is less than ʎo/21, is proven to achieve more than 85% of power harvesting efficiency at 0.348 THz. Furthermore, the infrared energy harvesters are fabricated using nano-fabrication tools. At last, the infrared harvesters are experimentally validated with the numerical findings using THz time-domain spectroscopy (THz-TDS).1 yea

Three-stage pyrolysis–steam reforming–water gas shift processing of household, commercial and industrial waste plastics for hydrogen production

Five common single plastics and nine different household, commercial and industrial waste plastics were processed using a three-stage (i) pyrolysis, (ii) catalytic steam reforming and (iii) water gas shift reaction system to produce hydrogen. Pyrolysis of plastics produces a range of different hydrocarbon species which are subsequently catalytically steam reformed to produce H2 and CO and then undergo water gas shift reaction to produce further H2. The process mimics the commercial process for hydrogen production from natural gas. Processing of the single polyalkene plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP)) produced similar H2 yields between 115 mmol and 120 mmol per gram plastic. Even though PS produced an aromatic product slate from the pyrolysis stage, further stages of reforming and water gas shift reaction produced a gas yield and composition similar to that of the polyalkene plastics (115 mmol H2 per gram plastic). PET gave significantly lower H2 yield (41 mmol per gram plastic) due to the formation of mainly CO, CO2 and organic acids from the pyrolysis stage which were not conducive to further reforming and water gas shift reaction. A mixture of the single plastics typical of that found in municipal solid waste produced a H2 yield of 102 mmol per gram plastic. Knowing the gas yields and composition from the single plastics enabled an estimation of the yields from a simulated waste plastic mixture and a ‘real-world’ waste plastic mixture to be determined. The different household, commercial and industrial waste plastic mixtures produced H2 yields between 70 mmol and 107 mmol per gram plastic. The H2 yield and gas composition from the single waste plastics gave an indication of the type of plastics in the mixed waste plastic samples

Chemical Synthesis of Copper Nanospheres and Nanocubes and Their Antibacterial Activity Against Escherichia coli and Enterococcus sp.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. The fulltext can also be viewed at this link: http://rdcu.be/mVXDThe interest in synthesising inorganic nanomaterials for biological applications has increased in recent years, especially for antibacterial purposes. In the present study, spherical and cube-shaped copper nanoparticles were synthesised by a chemical reduction method and their efficacy as antimicrobial agents against both Gram-negative (Escherichia coli) and Gram-positive (Enterococcus sp.) organisms investigated. The nanoparticles were characterised using ultraviolet/visible spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. Copper nanocubes were found to be more antimicrobial when compared with copper nanospheres, and it is postulated that whilst both sets of nanoparticles have similar total surface areas, the different shapes have different active facets and surface energies, which may lead to differing bactericidal behaviour

Optimizing technical and economic aspects of off-grid hybrid renewable systems: A case study of Manoka Island, Cameroon

The lack of accessible and reliable electrical energy in Cameroon has become a pervasive obstacle to the nation\u27s progress, with energy availability, quality, and cost identified as key hindrances to development over the past 15 years. Conventional solutions that rely on combustion engines and electrochemical storage systems have proven to be cost-prohibitive, limited in power output, and constrained in capacity. The dependence on traditional diesel generators has perpetuated maintenance challenges and a continuous demand for fuel supply, while the accompanying noise and pollution have restricted their use in residential areas. Recognizing the imperative of reducing dependence on fossil fuels and curbing greenhouse gas emissions, the need for clean and sustainable energy sources has emerged as a critical concern for the advancement of civilization. Against this backdrop, this research endeavors to identify the most cost-effective and efficient blend of renewable energy sources capable of meeting the power requirements of three small communities on Manoka Island, a district of Douala, Cameroon. Through a comprehensive technical, environmental, and economic analysis, this study addresses the substantial energy needs of 334 households, with an average daily power consumption of 1082.90 kWh and a peak electrical load of 183.99 kW. Leveraging the Hybrid Optimization Model for Electric Renewables (HOMER) program, this investigation assesses the feasibility of implementing Hybrid Renewable Energy Systems (HRES) to meet the region\u27s energy demands. The research highlights the most optimal scenario integrating solar panels, wind turbines, battery cells, fuel cell generators, biogas, and an electrolyzer within an off-grid HRES system. Notably, the study demonstrated an absence of idle load, resulting in remarkably low unit energy costs of { \ } $0.1981 and a compelling net present value of$ { \ } 2,209,741. The cost-effective arrangement featured 201 batteries, yielding a project profit of { \ } $ 57,387, with an impressive Internal Rate of Return (IRR) of 9.09%, Return on Investment (ROI) of 6.19%, and a payback period of 8.76 years over a 25-year term. In essence, the insights gleaned from this exploration of hybrid energy systems represent a pioneering case study in sustainable electricity provision. This research significantly contributes to the knowledge base on renewable energy within the nation, underscoring its tremendous potential for sustainable development and energy security

The metabolomic analysis of five Mentha species: cytotoxicity, anti-Helicobacter assessment, and the development of polymeric micelles for enhancing the anti-Helicobacter activity

Mentha species are medicinally used worldwide and remain attractive for research due to the diversity of their phytoconstituents and large therapeutic indices for various ailments. This study used the metabolomics examination of five Mentha species (M. suaveolens, M. sylvestris, M. piperita, M. longifolia, and M. viridis) to justify their cytotoxicity and their anti-Helicobacter effects. The activities of species were correlated with their phytochemical profiles by orthogonal partial least square discriminant analysis (OPLS-DA). Tentatively characterized phytoconstituents using liquid chromatography high-resolution electrospray ionization mass spectrometry (LC-HR-ESI-MS) included 49 compounds: 14 flavonoids, 10 caffeic acid esters, 7 phenolic acids, and other constituents. M. piperita showed the highest cytotoxicity to HepG2 (human hepatoma), MCF-7 (human breast adenocarcinoma), and CACO2 (human colon adenocarcinoma) cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. OPLS-DA and dereplication studies predicted that the cytotoxic activity was related to benzyl glucopyranoside-sulfate, a lignin glycoside. Furthermore, M. viridis was effective in suppressing the growth of Helicobacter pylori at a concentration of 50 mg mL−1. OPLS-DA predicted that this activity was related to a dihydroxytrimethoxyflavone. M. viridis extract was formulated with Pluronic® F127 to develop polymeric micelles as a nanocarrier that enhanced the anti-Helicobacter activity of the extract and provided minimum inhibitory concentrations and minimum bactericidal concentrations of 6.5 and 50 mg mL−1, respectively. This activity was also correlated to tentatively identified constituents, including rosmarinic acid, catechins, carvone, and piperitone oxide

The Association between Body Dysmorphic Disorder (BDD) and Acceptance of Cosmetic Surgery Scale (ACSS): A nationwide study from 25 medical schools

Background: Body dysmorphic disorder (BDD) is a psychological condition that is characterized by obsessive thinking about a perceived flaw in one's appearance that may eventually cause significant distress and impairment in life.Methods: A cross-sectional study was conducted between January 2021 and August 2021 using a previously validated and published questionnaires — The Body Image Disturbance Questionnaire (BIDQ) and Acceptance of Cosmetic Surgery Scale (ACSS).  Distributed to all medical students from 25 universities across all regions of Saudi Arabia. Results: A total of 1,776 respondents completed the questionnaire. Females represented 57.1% of the study population.More than half of the respondents were concerned and preoccupied with their body appearance (59.4% and 52.8%, respectively). The average of the BIDQ and ACSS scores was significantly higher in females compared to males, while higher socioeconomic status and higher educational level were also significantly related with higher BIDQ and ACSS scores. Furthermore, a higher BIDQ score was associated with higher scores on the ACSS

Management of multi-language business processes with "AProMoRe"

International audienceAPROMORE (Advanced PROocess MOdel REpository) is an open and extensible plat- form meant to face the challenge of how to deal with an increasing number of business process models within or accross organisations

Management of multi-language business processes with "AProMoRe"

International audienceAPROMORE (Advanced PROocess MOdel REpository) is an open and extensible plat- form meant to face the challenge of how to deal with an increasing number of business process models within or accross organisations