Iron and virulence in Stenotrophomonas maltophilia: all we know so far

Stenotrophomonas maltophilia is a multi-drug-resistant global opportunistic nosocomial pathogen, which possesses a huge number of virulence factors and antibiotics resistance characteristics. Iron has a crucial contribution toward growth and development, cell growth and proliferation, and pathogenicity. The bacterium found to acquire iron for its cellular process through the expression of two iron acquisition systems. Two distinct pathways for iron acquisition are encoded by the S. maltophilia genome-a siderophore-and heme-mediated iron uptake system. The entAFDBEC operon directs the production of the enterobactin siderophore of catecholate in nature, while heme uptake relies on hgbBC and potentially hmuRSTUV operon. Fur and sigma factors are regulators of S. maltophilia under iron-limited condition. Iron potentially act as a signal which plays an important role in biofilm formation, extracellular polymeric substances (EPS), extracellular enzymes production, oxidative stress response, diffusible signal factor (DSF) and siderophore production in S. maltophilia. This review summarizes the current knowledge of iron acquisition in S. maltophilia and the critical role of iron in relation to its pathogenicity

The 'checkmate' for iron between human host and invading bacteria: chess game analogy

Iron is an essential nutrient for all living organisms with critical roles in many biological processes. The mammalian host maintains the iron requirements by dietary intake, while the invading pathogenic bacteria compete with the host to obtain those absorbed irons. In order to limit the iron uptake by the bacteria, the human host employs numerous iron binding proteins and withholding defense mechanisms that capture iron from the microbial invaders. To counteract, the bacteria cope with the iron limitation imposed by the host by expressing various iron acquisition systems, allowing them to achieve effective iron homeostasis. The armamentarium used by the human host and invading bacteria, leads to the dilemma of who wins the ultimate war for iron

Nano additive enhanced salt hydrate phase change materials for thermal energy storage

Energy storage plays a vital role in sustainable development. Focus on energy storage using phase change materials (PCMs) are of current research hotspot due to high latent heat value. Nevertheless, poor thermal conductivity, supercooling, phase separation, corrosive nature of salt hydrate is of great concern. Distress related to properties of PCM is resolved using nano additives. Major research focus on the dispersion of nano additive with PCM depends on (a) technique of preparing a novel composite PCM; (b) improvement of their thermophysical characteristic; and (c) advanced application for human comfort without polluting the environment. This article presents a critical review of hybridization techniques of metal, carbon and polymer additives on salt hydrate PCMs. To facilitate researchers, the significant variation on thermophysical properties of salt hydrate with nano additives are vitally compared, analysed and critically reviewed. This review article also includes the advanced application of nano additives-based salt hydrate PCMs

Nano-enhanced phase change materials: Fundamentals and applications

Phase Change Materials (PCMs) enable thermal energy storage in the form of latent heat during phase transition. PCMs significantly improve the efficiency of solar power systems by storing excess energy, which can be used during peak demand. Likewise, they also contribute to reduced overall energy demand through passive thermal regulation. Nonetheless, thermal energy charging and discharging are restricted due to the low conducting nature of the energy storage medium. Various research investigations are being carried out to improve the thermal characteristics of PCMs through techniques such as a) dispersion of nanoparticles, b) inserting fins, and c) cascading PCMs. Among the techniques mentioned above, the dispersion of nanoparticles is reliable and economically viable. These materials are so-called nano-enhanced PCMs (NePCMs) that facilitate the charging and discharging processes of the thermal energy storage (TES) units owing to their improved thermo physical properties and long term stability. This paper presents a comprehensive review with implications and inferences on research conducted using nano-enhanced phase change materials (NePCMs) in recent years. Initially, the article discusses the highly preferred synthesis methods of NePCMs in addition to its morphological and thermophysical characterization techniques. Then, an acute focus on the impact of distinct dimensional nano additives like zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) on inclusion with PCMs are elaborately discussed. A deep discussion on emerging and hybrid nanoparticles dispersed PCMs with emphasis on a) the interaction mechanism of nanoparticle & phase change material (PCM) and b) influences on enhancing the thermophysical properties (melting point, thermal conductivity, latent heat capacity, thermal diffusivity, and thermal stability) of NePCMs are discussed. Indeed, including nanomaterials within the PCM matrix resulted in variations in thermal conductivity and heat storage enthalpy. With nanomaterial NePCM displayed 80–150 % increment in organic PCM as their proportion of nanomaterial inclusion is about 1–2 %, whereas for form and shape stable PCM enhancement of 700–900 % in thermal conductivity is noticed; however, there was a drop in heat storage enthalpy owing to the inclusion of nanomaterial in weight fraction of 5–20 %. Furthermore included in this review article are insights on significant advances, challenges, and outlooks for enhancing NePCMs in the field of advanced thermal applications. This review article is expected to have a particular reference value that would provide notable insight to readers to explore the fundamental properties of NePCM further. Additionally, as there is alarming interest in the field of TES late after the framework of sustainable development goals (SDG)s by the United Nations in 2015, this review article is anticipated to make a remarkable impact towards SDG 7-Affordable and Clean Energy, by providing technical insights towards enhancing the renewable energy sources assisted with TES

Investigation of thermal performance and chemical stability of graphene enhanced phase change material for thermal energy storage

Phase change materials (PCMs) have received widespread thermal energy storage (TES) and release properties due to their unique characteristics. However, the PCMs suffer from poor thermal conductivity, resulting in the least thermal performance and heat transfer characteristics. This research focused on enhancing the heat transfer and storage characteristics by developing an organic paraffin wax composite by dispersing highly conductive graphene powder using a two-step technique. The results show that the developed nano enhanced PCM significantly improves the thermal conductivity by 72.2 at 0.6Â wt of graphene powder. Furthermore, the Fourier transform infrared spectrum shows there is no additional peak observed, means physically and chemically stable, and the reduced light transmission capability was enhanced by 32.0 than pure PCM. Due to its extreme characteristics, the developed PCM is an outstanding material for medium temperature solar thermal energy storage applications

Experimental Investigation of Graphene Nanoplatelets Enhanced Low Temperature Ternary Eutectic Salt Hydrate Phase Change Material

A sustainable approach to ensuring the thermal regulation of space is reliable with phase change materials (PCMs) operating at 15–25 °C. Henceforth, there is a need of a search of binary and ternary eutectic PCMs operating at desirable phase transition temperatures of 15–25 °C, high energy storage enthalpy (180–220 J/g), improved thermal conductivity and better absorptivity of solar energy. In this current research, we developed a ternary eutectic inorganic salt hydrate PCM intended for a low-temperature thermal regulation system. Based on the eutectic melting point theory, the phase transition temperature and proportion of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD) and sodium sulphate decahydrate (SSD) were determined. As per the calculated proportion, ternary eutectic PCM was experimentally prepared. Furthermore, to enhance the thermal property, graphene nanoplatelets (GNP) were dispersed at weight concentrations of 0.4%, 0.7% and 1.0%. The prepared nanoparticle-dispersed PCMs were characterized using an optical microscope, Fourier transform infrared (FT-IR) spectroscopy and a thermal conductivity meter, and a differential scanning calorimeter (DSC) was used to evaluate the morphology, chemical stability and thermal properties. The results showed increases in thermal conductivity and optical absorbance by 71.5% and 106.5%, respectively, with GNP at 1.0% weight concentration. Similarly, the degree of supercooling and transmissibility was reduced by 43.5% and 76.2% correspondingly. The prepared composite PCM is expected to contribute towards cooling, with an intention to contribute towards sustainable development

Bovine serum albumin-conjugated ferrimagnetic iron oxide nanoparticles to enhance the biocompatibility and magnetic hyperthermia performance

10.1007/s40820-015-0065-1Nano-Micro Letters8180-9

Experimental Investigation of Graphene Nanoplatelets Enhanced Low Temperature Ternary Eutectic Salt Hydrate Phase Change Material

A sustainable approach to ensuring the thermal regulation of space is reliable with phase change materials (PCMs) operating at 15–25 °C. Henceforth, there is a need of a search of binary and ternary eutectic PCMs operating at desirable phase transition temperatures of 15–25 °C, high energy storage enthalpy (180–220 J/g), improved thermal conductivity and better absorptivity of solar energy. In this current research, we developed a ternary eutectic inorganic salt hydrate PCM intended for a low-temperature thermal regulation system. Based on the eutectic melting point theory, the phase transition temperature and proportion of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD) and sodium sulphate decahydrate (SSD) were determined. As per the calculated proportion, ternary eutectic PCM was experimentally prepared. Furthermore, to enhance the thermal property, graphene nanoplatelets (GNP) were dispersed at weight concentrations of 0.4%, 0.7% and 1.0%. The prepared nanoparticle-dispersed PCMs were characterized using an optical microscope, Fourier transform infrared (FT-IR) spectroscopy and a thermal conductivity meter, and a differential scanning calorimeter (DSC) was used to evaluate the morphology, chemical stability and thermal properties. The results showed increases in thermal conductivity and optical absorbance by 71.5% and 106.5%, respectively, with GNP at 1.0% weight concentration. Similarly, the degree of supercooling and transmissibility was reduced by 43.5% and 76.2% correspondingly. The prepared composite PCM is expected to contribute towards cooling, with an intention to contribute towards sustainable development

Graphene–Silver Hybrid Nanoparticle based Organic Phase Change Materials for Enhanced Thermal Energy Storage

Due to the intermittent nature of solar energy, researchers and scientists are working to develop thermal energy storage (TES) systems for effective utilization of solar energy. Phase change materials (PCMs) are considered to be promising materials for TES. In this study, organic paraffin RT50 and graphene silver (Gr:Ag) nanopowder are adopted as TES material and thermal property enhancers. Microstructure and morphological behavior as well as chemical, optical, and thermal stability of the prepared composite PCM are visually investigated using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, thermal conductivity analyzer, differential scanning calorimeter (DSC). and thermogravimetric analyzer (TGA). Furthermore, based on the outstanding thermal performance of the composite, an extended investigation on the thermal and chemical properties are evaluated for 500 thermal cycles to ensure their reliability. Results show the thermal conductivity of RT50 improved by 53.85% when Gr:Ag nanopowder is dispersed at a weight percent of 0.8 (RT50-0.8Gr:Ag). The change in latent heat value of the composite sample is less than 3%, which is significant for effective thermal energy storage. The thermal decomposition of RT50 is slightly improved from 300 °C to 330 °C. To ensure a reliable and passive technique for thermal energy storage within solar thermal application devices, such as solar air heaters and solar photovoltaic thermal systems, using nanoparticle enhanced PCMs at the range of a 50 °C melting point are a current research hotspot