In situ Growth of Zeolite Imidazole Frameworks (ZIF-67) on Carbon Cloth for the Application of Oxygen Reduction Reactions and Microbial Fuel Cells.

Developing high surface area catalysts is an effective strategy to enhance the oxygen reduction reaction (ORR) in the application of microbial fuel cells (MFCs). This can be achieved by developing a catalyst based on metal-organic frameworks (MOFs) because they offer a porous active site for ORR. In this work, a novel in situ growth of 2D shell nanowires of ZIF-67 as a template for N-doped carbon (Co/NC) via a carbonization route was developed to enhance the ORR performance. The effects of different reaction times and different annealing temperatures were studied for a better ORR activity. The growth of the MOF template on the carbon cloth was confirmed using scanning electron microscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared. The Co/NC-800 exhibited an enhancement in the ORR activity as evidenced by an onset potential and half-wave potential of 0.0 vs V Ag/AgCl and -0.1 vs V Ag/AgCl, respectively, with a limited current density exceeding the commercial Pt/C. Operating Co/NC-800 on MFC revealed a maximum power density of 30 ± 2.5 mW/m2, a maximum current density of 180 ± 2.5 mA/m2.

Nanoengineered, Pd-doped Co@C nanoparticles as an effective electrocatalyst for OER in alkaline seawater electrolysis.

Water electrolysis is considered one of the major sources of green hydrogen as the fuel of the future. However, due to limited freshwater resources, more interest has been geared toward seawater electrolysis for hydrogen production. The development of effective and selective electrocatalysts from earth-abundant elements for oxygen evolution reaction (OER) as the bottleneck for seawater electrolysis is highly desirable. This work introduces novel Pd-doped Co nanoparticles encapsulated in graphite carbon shell electrode (Pd-doped CoNPs@C shell) as a highly active OER electrocatalyst towards alkaline seawater oxidation, which outperforms the state-of-the-art catalyst, RuO2. Significantly, Pd-doped CoNPs@C shell electrode exhibiting low OER overpotential of ≈213, ≈372, and ≈ 429 mV at 10, 50, and 100 mA/cm2, respectively together with a small Tafel slope of ≈ 120 mV/dec than pure Co@C and Pd@C electrode in alkaline seawater media. The high catalytic activity at the aforementioned current density reveals decent selectivity, thus obviating the evolution of chloride reaction (CER), i.e., ∼490 mV, as competitive to the OER. Results indicated that Pd-doped Co nanoparticles encapsulated in graphite carbon shell (Pd-doped CoNPs@C electrode) could be a very promising candidate for seawater electrolysis.

Membrane processes for environmental remediation of nanomaterials: Potentials and challenges.

Nanomaterials have gained huge attention with their wide range of applications. This is mainly driven by their unique properties. Nanomaterials include nanoparticles, nanotubes, nanofibers, and many other nanoscale structures have been widely assessed for improving the performance in different applications. However, with the wide implementation and utilization of nanomaterials, another challenge is being present when these materials end up in the environment, i.e. air, water, and soil. Environmental remediation of nanomaterials has recently gained attention and is concerned with removing nanomaterials from the environment. Membrane filtration processes have been widely considered a very efficient tool for the environmental remediation of different pollutants. Membranes with their different operating principles from size exclusions as in microfiltration, to ionic exclusion as in reverse osmosis, provide an effective tool for the removal of different types of nanomaterials. This work comprehends, summarizes, and critically discusses the different approaches for the environmental remediation of engineered nanomaterials using membrane filtration processes. Microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) have been shown to effectively remove nanomaterials from the air and aqueous environments. In MF, the adsorption of nanomaterials to membrane material was found to be the main removal mechanism. While in UF and NF, the main mechanism was size exclusion. Membrane fouling, hence requiring proper cleaning or replacement was found to be the major challenge for UF and NF processes. While limited adsorption capacity of nanomaterial along with desorption was found to be the main challenges for MF.

Amplification of Inflammation by Lubricin Deficiency Implicated in Incident, Erosive Gout Independent of Hyperuricemia.

OBJECTIVE: In gout, hyperuricemia promotes urate crystal deposition, which stimulates the NLRP3 inflammasome and interleukin-1ß (IL-1ß)-mediated arthritis. Incident gout without background hyperuricemia is rarely reported. To identify hyperuricemia-independent mechanisms driving gout incidence and progression, we characterized erosive urate crystalline inflammatory arthritis in a young female patient with normouricemia diagnosed as having sufficient and weighted classification criteria for gout according to the American College of Rheumatology (ACR)/EULAR gout classification criteria (the proband). METHODS: We conducted whole-genome sequencing, quantitative proteomics, whole-blood RNA-sequencing analysis using serum samples from the proband. We used a mouse model of IL-1ß-induced knee synovitis to characterize proband candidate genes, biomarkers, and pathogenic mechanisms of gout. RESULTS: Lubricin level was attenuated in human proband serum and associated with elevated acute-phase reactants and inflammatory whole-blood transcripts and transcriptional pathways. The proband had predicted damaging gene variants of NLRP3 and of inter-α trypsin inhibitor heavy chain 3, an inhibitor of lubricin-degrading cathepsin G. Changes in the proband's serum protein interactome network supported enhanced lubricin degradation, with cathepsin G activity increased relative to its inhibitors, SERPINB6 and thrombospondin 1. Activation of Toll-like receptor 2 (TLR-2) suppressed levels of lubricin mRNA and lubricin release in cultured human synovial fibroblasts (P < 0.01). Lubricin blunted urate crystal precipitation and IL-1ß induction of xanthine oxidase and urate in cultured macrophages (P < 0.001). In lubricin-deficient mice, injection of IL-1ß in knees increased xanthine oxidase-positive synovial resident M1 macrophages (P < 0.05). CONCLUSION: Our findings linked normouricemic erosive gout to attenuated lubricin, with impaired control of cathepsin G activity, compounded by deleterious NLRP3 variants. Lubricin suppressed monosodium urate crystallization and blunted IL-1ß-induced increases in xanthine oxidase and urate in macrophages. The collective activities of articular lubricin that could limit incident and erosive gouty arthritis independently of hyperuricemia are subject to disruption by inflammation, activated cathepsin G, and synovial fibroblast TLR-2 signaling.

Recent progress in renewable energy based-desalination in the Middle East and North Africa MENA region.

BACKGROUND: The Middle East and North Africa (MENA) countries are rapidly growing in population with very limited access to freshwater resources. To overcome this challenge, seawater desalination is proposed as an effective solution, as most MENA countries have easy access to saline water. However, desalination processes have massive demand for energy, which is mostly met by fossil fuel-driven power plants. The rapid technological advancements in renewable energy technologies, along with their gradually decreasing cost place renewable energy-driven power plants and processes as a promising alternative to conventional fuel-powered plants. AIM OF REVIEW: In the current work, renewable energy-powered desalination in the MENA region is investigated. Various desalination technologies and renewable energy resources, particularly those available in MENA are discussed. A detailed discussion of suitable energy storage technologies for incorporation into renewable energy desalination systems is also included. KEY SCIENTIFIC CONCEPTS OF REVIEW: The progress made in implementing renewable energy into power desalination plants in MENA countries is summarized and analyzed by describing the overall trend and giving recommendations for the potential amalgamation of available renewable energies (REs) and available desalination technologies. Finally, a case study in the MENA region, the Al Khafji solar seawater reverse osmosis (SWRO) desalination plant in the Kingdom of Saudi Arabia KSA, is used to demonstrate the implementation of REs to drive desalination processes.

Protein phosphatase 2A regulates xanthine oxidase-derived ROS production in macrophages and influx of inflammatory monocytes in a murine gout model.

Background: Gout is a common arthritis, due to deposition of monosodium urate (MSU) crystals which results in IL-1ß secretion by tissue-resident macrophages. Xanthine oxidase (XO) catalyzes uric acid (UA) production and in the process, reactive oxygen species (ROS) are generated which contributes to NLRP3 inflammasome activation. Protein phosphatase 2A (PP2A) may be involved in regulating inflammatory pathways in macrophages. The objective of this study was to investigate whether PP2A regulates gout inflammation, mediated by XO activity modulation. We studied UA and ROS generations in MSU stimulated murine bone marrow derived macrophages (BMDMs) in response to fingolimod phosphate, a PP2A activator, and compared its anti-inflammatory efficacy to that of an XO inhibitor, febuxostat. Methods: BMDMs were stimulated with MSU, GM-CSF/IL-1ß or nigericin ± fingolimod (2.5 µM) or febuxostat (200 µM) and UA levels, ROS, XO, and PP2A activities, Xdh (XO) expression and secreted IL-1ß levels were determined. PP2A activity and IL-1ß in MSU stimulated BMDMs ± N-acetylcysteine (NAC) (10 µM) ± okadaic acid (a PP2A inhibitor) were also determined. M1 polarization of BMDMs in response to MSU ± fingolimod treatment was assessed by a combination of iNOS expression and multiplex cytokine assay. The in vivo efficacy of fingolimod was assessed in a murine peritoneal model of acute gout where peritoneal lavages were studied for pro-inflammatory classical monocytes (CMs), anti-inflammatory nonclassical monocytes (NCMs) and neutrophils by flow cytometry and IL-1ß by ELISA. Results: Fingolimod reduced intracellular and secreted UA levels (p < 0.05), Xdh expression (p < 0.001), XO activity (p < 0.001), ROS generation (p < 0.0001) and IL-1ß secretion (p < 0.0001), whereas febuxostat enhanced PP2A activity (p < 0.05). NAC treatment enhanced PP2A activity and reduced XO activity and PP2A restoration mediated NAC's efficacy as co-treatment with okadaic acid increased IL-1ß secretion (p < 0.05). Nigericin activated caspase-1 and reduced PP2A activity (p < 0.001) and fingolimod reduced caspase-1 activity in BMDMs (p < 0.001). Fingolimod reduced iNOS expression (p < 0.0001) and secretion of IL-6 and TNF-α (p < 0.05). Fingolimod reduced CMs (p < 0.0001), neutrophil (p < 0.001) and IL-1ß (p < 0.05) lavage levels while increasing NCMs (p < 0.001). Conclusion: Macrophage PP2A is inactivated in acute gout by ROS and a PP2A activator exhibited a broad anti-inflammatory effect in acute gout in vitro and in vivo.

Exploratory Analysis of Outpatient Visits for US Adults Diagnosed with Lupus Erythematosus: Findings from the National Ambulatory Medical Care Survey 2006-2016.

The study aims to assess office-based visit trends for lupus patients and evaluate their medication burden, chronic conditions, and comorbidities. This cross-sectional study used data from the National Ambulatory Medical Care Survey (NAMCS), a survey sample weighted to represent national estimates of outpatient visits. Adult patients diagnosed with lupus were included. Medications and comorbidities that were frequently recorded were identified and categorized. Descriptive statistics and bivariate analyses were used to characterize visits by sex, age, race/ethnicity, insurance type, region, and reason for visit. Comorbidities were identified using diagnosis codes documented at each encounter. There were 27,029,228 visits for lupus patients from 2006 to 2016, and 87% them were on or were prescribed medications. Most visits were for female (88%), white (79%), non-Hispanic (88%) patients with private insurance (53%). The majority of patients were seen for a chronic routine problem (75%), and 29% had lupus as the primary diagnosis. Frequent medications prescribed were hydroxychloroquine (30%), prednisone (23%), multivitamins (14%), and furosemide (9%). Common comorbidities observed included arthritis (88%), hypertension (25%), and depression (13%). Prescription patterns are reflective of comorbidities associated with lupus. By assessing medications most frequently prescribed and comorbid conditions among lupus patients, we showcase the complexity of disease management and the need for strategies to improve care.

Impact of COVID-19 on the Renewable Energy Sector and Mitigation Strategies.

This review explores the impact of the COVID-19 pandemic on the renewable energy (RE) sector, especially in countries with the highest RE capacities, e.g., the USA, China, India, and the EU. It highlights stimulus packages put in place by governments worldwide and their sustainability to cushion the RE sector. Commissioning of RE projects has stalled due to lack of funding allocation and interruptions in the supply of equipment and components due to lockdown measures. Despite the need to fund COVID-19 vaccination programs and other related health services, the world must not neglect other sectors of the economy, creating more problems, such as worsening the climate change situation in the long run. This review aims to present the information needed to sustain future energy during the COVID-19 global pandemic.

Quadruped Gait and Regulation of Apoptotic Factors in Tibiofemoral Joints following Intra-Articular rhPRG4 Injection in Prg4 Null Mice.

Camptodactyly-arthropathy-coxa vara-pericarditis (CACP) syndrome leads to diarthrodial joint arthropathy and is caused by the absence of lubricin (proteoglycan 4-PRG4), a surface-active mucinous glycoprotein responsible for lubricating articular cartilage. In this study, mice lacking the orthologous gene Prg4 served as a model that recapitulates the destructive arthrosis that involves biofouling of cartilage by serum proteins in lieu of Prg4. This study hypothesized that Prg4-deficient mice would demonstrate a quadruped gait change and decreased markers of mitochondrial dyscrasia, following intra-articular injection of both hindlimbs with recombinant human PRG4 (rhPRG4). Prg4-/- (N = 44) mice of both sexes were injected with rhPRG4 and gait alterations were studied at post-injection day 3 and 6, before joints were harvested for immunohistochemistry for caspase-3 activation. Increased stance and propulsion was shown at 3 days post-injection in male mice. There were significantly fewer caspase-3-positive chondrocytes in tibiofemoral cartilage from rhPRG4-injected mice. The mitochondrial gene Mt-tn, and myosin heavy (Myh7) and light chains (Myl2 and Myl3), known to play a cytoskeletal stabilizing role, were significantly upregulated in both sexes (RNA-Seq) following IA rhPRG4. Chondrocyte mitochondrial dyscrasias attributable to the arthrosis in CACP may be mitigated by IA rhPRG4. In a supporting in vitro crystal microbalance experiment, molecular fouling by albumin did not block the surface activity of rhPRG4.

All Transition Metal Selenide Composed High-Energy Solid-State Hybrid Supercapacitor.

Transition metal selenides (TMSs) have enthused snowballing research and industrial attention due to their exclusive conductivity and redox activity features, holding them as great candidates for emerging electrochemical devices. However, the real-life utility of TMSs remains challenging owing to their convoluted synthesis process. Herein, a versatile in situ approach to design nanostructured TMSs for high-energy solid-state hybrid supercapacitors (HSCs) is demonstrated. Initially, the rose-nanopetal-like NiSe@Cu2 Se (NiCuSe) positive electrode and FeSe nanoparticles negative electrode are directly anchored on Cu foam via in situ conversion reactions. The complementary potential windows of NiCuSe and FeSe electrodes in aqueous electrolytes associated with the excellent electrical conductivity results in superior electrochemical features. The solid-state HSCs cell manages to work in a high voltage range of 0-1.6 V, delivers a high specific energy density of 87.6 Wh kg-1 at a specific power density of 914.3 W kg-1 and excellent cycle lifetime (91.3% over 10 000 cycles). The innovative insights and electrode design for high conductivity holds great pledge in inspiring material synthesis strategies. This work offers a feasible route to develop high-energy battery-type electrodes for next-generation hybrid energy storage systems.

Solution Combustion Synthesis of Novel S,B-Codoped CoFe Oxyhydroxides for the Oxygen Evolution Reaction in Saline Water.

Green hydrogen presents itself as a clean energy vector, which can be produced by electrolysis of water by utilizing renewable energy such as solar or wind. While current technologies are sufficient to support commercial deployment of fresh water electrolyzers, there remain a few well-defined challenges in the path of commercializing direct seawater electrolyzers, predominantly related to the sluggish oxygen evolution reaction (OER) kinetics and the competing chlorine evolution reaction (CER) at the anode. Herein, we report the facile and swift fabrication of an S,B-codoped CoFe oxyhydroxide via solution combustion synthesis for the OER with apparent CER suppression abilities. The as-prepared S,B-(CoFe)OOH-H attained ultralow overpotentials of 161 and 278 mV for achieving current densities of 10 and 1000 mA cm-2, respectively, in an alkaline saline (1 M KOH + 0.5 M NaCl) electrolyte, with a low Tafel slope of 46.7 mV dec-1. Chronoamperometry testing of the codoped bimetallic oxyhydroxides showed very stable behavior in harsh alkaline saline and in neutral pH saline environments. S,B-(CoFe)OOH-H oxyhydroxide showed a notable decrease in CER production in comparison to the other S,B-codoped counterparts. Selectivity measurements through online FE calculations showed high OER selectivity in alkaline (FE ∼ 97%) and neutral (FE ∼ 91%) pH saline conditions under standard 10 mA cm-2 operation. Moreover, systematic testing in electrolytes at pH values of 14 to 7 yielded promising results, thus bringing direct seawater electrolysis at near-neutral pH conditions closer to realization.

Early Transition-Metal-Based Binary Oxide/Nitride for Efficient Electrocatalytic Hydrogen Evolution from Saline Water in Different pH Environments.

Using abundant seawater can reduce reliance on freshwater resources for hydrogen production from electrocatalytic water splitting. However, seawater has detrimental effects on the stability and activity of the hydrogen evolution reaction (HER) electrocatalysts under different pH conditions. In this work, we report the synthesis of binary metallic core-sheath nitride@oxynitride electrocatalysts [Ni(ETM)]δ+-[O-N]δ-, where ETM is an early transition metal V or Cr. Using NiVN on a nickel foam (NF) substrate, we demonstrate an HER overpotential as low as 32 mV at -10 mA cm-2 in saline water (0.6 M NaCl). The results represent an advancement in saline water HER performance of earth-abundant electrocatalysts, especially under near-neutral pH range (i.e., pH 6-8). Doping ETMs in nickel oxynitrides accelerates the typically rate-determining H2O dissociation step for HER and suppresses chloride deactivation of the catalyst in neutral-pH saline water. Heterointerface synergism occurs through H2O adsorption and dissociation at interfacial oxide character, while adsorbed H* proceeds via Heyrovsky or Tafel step on the nitride character. This electrocatalyst showed stable performance under a constant current density of -50 mA cm-2 for 50 h followed by additional 50 h at -100 mA cm-2 in a neutral saline electrolyte (1 M PB + 0.6 M NaCl). Contrarily, under the same conditions, Pt/C@NF exhibited significantly low performance after a mere 4 h at -50 mA cm-2. The low Tafel slope of 25 mV dec-1 indicated that the reaction is Tafel limited, unlike commercial Pt/C, which is Heyrovsky limited. We close by discussing general principles concerning surface charge delocalization for the design of HER electrocatalysts in pH saline environments.

Proteoglycan-4 is an essential regulator of synovial macrophage polarization and inflammatory macrophage joint infiltration.

BACKGROUND: Synovial macrophages perform a multitude of functions that include clearance of cell debris and foreign bodies, tissue immune surveillance, and resolution of inflammation. The functional diversity of macrophages is enabled by distinct subpopulations that express unique surface markers. Proteoglycan-4 (PRG4) is an important regulator of synovial hyperplasia and fibrotic remodeling, and the involvement of macrophages in PRG4's synovial role is yet to be defined. Our objectives were to study the PRG4's importance to macrophage homeostatic regulation in the synovium and infiltration of pro-inflammatory macrophages in acute synovitis and investigate whether macrophages mediated synovial fibrosis in Prg4 gene-trap (Prg4GT/GT) murine knee joints. METHODS: Macrophage phenotyping in Prg4GT/GT and Prg4+/+ joints was performed by flow cytometry using pan-macrophage markers, e.g., CD11b, F4/80, and surface markers of M1 macrophages (CD86) and M2 macrophages (CD206). Characterizations of the various macrophage subpopulations were performed in 2- and 6-month-old animals. The expression of inflammatory markers, IL-6, and iNOS in macrophages that are CD86+ and/or CD206+ was studied. The impact of Prg4 recombination on synovial macrophage populations of 2- and 6-month-old animals and infiltration of pro-inflammatory macrophages in response to a TLR2 agonist challenge was determined. Macrophages were depleted using liposomal clodronate and synovial membrane thickness, and the expression of fibrotic markers α-SMA, PLOD2, and collagen type I (COL-I) was assessed using immunohistochemistry. RESULTS: Total macrophages in Prg4GT/GT joints were higher than Prg4+/+ joints (p<0.0001) at 2 and 6 months, and the percentages of CD86+/CD206- and CD86+/CD206+ macrophages increased in Prg4GT/GT joints at 6 months (p<0.0001), whereas the percentage of CD86-/CD206+ macrophages decreased (p<0.001). CD86+/CD206- and CD86+/CD206+ macrophages expressed iNOS and IL-6 compared to CD86-/CD206+ macrophages (p<0.0001). Prg4 re-expression limited the accumulation of CD86+ macrophages (p<0.05) and increased CD86-/CD206+ macrophages (p<0.001) at 6 months. Prg4 recombination attenuated synovial recruitment of pro-inflammatory macrophages in 2-month-old animals (p<0.001). Clodronate-mediated macrophage depletion reduced synovial hyperplasia, α-SMA, PLOD2, and COL-I expressions in the synovium (p<0.0001). CONCLUSIONS: PRG4 regulates the accumulation and homeostatic balance of macrophages in the synovium. In its absence, the synovium becomes populated with M1 macrophages. Furthermore, macrophages exert an effector role in synovial fibrosis in Prg4GT/GT animals.

Effects of COVID-19 on the environment: An overview on air, water, wastewater, and solid waste.

The COVID-19 pandemic has hit the world hardly as of the beginning of 2020 and quickly spread worldwide from its first-reported point in early Dec. 2019. By mid-March 2021, the COVID-19 almost hit all countries worldwide, with about 122 and 2.7 million confirmed cases and deaths, respectively. As a strong measure to stop the infection spread and deaths, many countries have enforced quarantine and lockdown of many activities. The shutdown of these activities has resulted in large economic losses. However, it has been widely reported that these measures have resulted in improved air quality, more specifically in highly polluted areas characterized by massive population and industrial activities. The reduced levels of carbon, nitrogen, sulfur, and particulate matter emissions have been reported and confirmed worldwide in association with lockdown periods. On the other hand, ozone levels in ambient air have been found to increase, mainly in response to the reduced nitrogen emissions. In addition, improved water quality in natural water resources has been reported as well. Wastewater facilities have reported a higher level of organic load with persistent chemicals due to the increased use of sanitizers, disinfectants, and antibiotics. The solid waste generated due to the COVID-19 pandemic was found to increase both qualitatively and quantitatively. This work presents and summarizes the observed environmental effects of COVID-19 as reported in the literature for different countries worldwide. The work provides a distinct overview considering the effects imposed by COVID-19 on the air, water, wastewater, and solid waste as critical elements of the environment.

Optimization of Fuel Cell Performance Using Computational Fluid Dynamics.

A low cost bipolar plate materials with a high fuel cell performance is important for the establishment of Proton Exchange Membrane (PEM ) fuel cells into the competitive world market. In this research, the effect of different bipolar plates material such as Aluminum (Al), Copper (Cu), and Stainless Steel (SS) of a single stack of proton exchange membrane (PEM) fuel cells was investigated both numerically and experimentally. Firstly, a three dimensional (3D) PEM fuel cell model was developed, and simulations were conducted using commercial computational fluid dynamics (CFD) ANSYS FLUENT to examine the effect of each bipolar plate materials on cell performance. Along with cell performance, significant parameters distributions like temperature, pressure, a mass fraction of hydrogen, oxygen, and water is presented. Then, an experimental study of a single cell of Al, Cu, and SS bipolar plate material was used in the verification of the numerical investigation. Finally, polarization curves of numerical and experimental results was compared for validation, and the result shows that Al serpentine bipolar plate material performed better than Cu and SS materials. The outcome of the investigation was in tandem to the fact that due to adsorption on metal surfaces, hydrogen molecules is more stable on Al surface than Cu and SS surfaces.

A critical review on environmental impacts of renewable energy systems and mitigation strategies: Wind, hydro, biomass and geothermal.

The annual growth of global energy demand and the associated environmental impacts (EIs) has an important role in the large sustainable and green global energy transition. Renewable energy systems have been attracting substantial economic, environmental, and technical attention throughout the last decade, while some have been in the market for almost a century. However, even renewable energy may negatively affect the environment, which is widely considered much less harsh than fossil energy resources. This, in return, requires more consideration and appropriate precautions to be taken. This work discusses the environmental impacts (EIs) of small and medium-sized wind, hydro, biomass, and geothermal power systems. The approach goes through all stages from planning and conception to construction and installation and throughout service life and decommissioning. For various circumstances and technically and ecologically viable guidelines for their effect on natural resources and wildlife, clear and comprehensive solutions have been given.

Environmental impacts of nanofluids: A review.

Nanofluids (NFs) have been expanding their applications in many areas as high-performance heat transfer fluid (HTF) for heating and cooling purposes. This is mainly due to the improved thermophysical properties relative to the base fluid (BF). The addition of nanoparticles (NPs) to BF, to obtain NFs, increases the thermal conductivity, hence better heat transfer properties and thermal performance. The properties of NFs can be considered somehow intermediate between those of the BF and the added solid NPs. The improved heat transfer using NFs results in increased energy conversion efficiency, which results in reduced energy consumption for heating or cooling applications. BF and their environmental impacts (EIs) have been widely discussed within the scope of their applications as a HTF, with most of the attention given to the improved energy efficiency. The IEs of NPs and their toxicity and other characteristics have been extensively studied due to the widespread applications on newly engineered NPs. However, with the evolution of expanding the applications of NFs, the different EIs were not well addressed. The discussion should consider both the base fluid and NPs added in combination as the NF constitutes. The current work presents a brief discussion on the EIs of NFs. The discussion presented in this work considers the NPs as the primary contributor to the EIs of different NFs. It was found that the EIs of NFs depend significantly on the type of NP used, followed by the BF, and finally, the loading of NPs in BF. The use of non-toxic and naturally occurring NPs at lower NPs loading in water as NF promises a much lower EIs in terms of toxicity energy requirements for production, and other EIs, while still maintaining high thermal performance. The production methods of both NPs, i.e., synthesis route, and NF, i.e., one-step or two-step, were found to have a significant effect on the associated EIs of the produced NF. The simpler NP synthesis route and NF production will result in much lower chemicals and energy requirements, which in turn reduce the EIs.

Evaluation of the nanofluid-assisted desalination through solar stills in the last decade.

Remote areas and poor communities are occasionally deprived of access to freshwater. It is, therefore, critical to providing a cheap and efficient desalination system that encourages the development of those communities and benefiting society at large. Solar stills are an affordable, direct method of water desalination, but its productivity is the critical challenge hindering its application. To ease this, research has focused on the role of nanofluids to improve heat transfer. Other works have focused on improving the design in consort with utilizing the nanofluids. This review reports and discusses the substantial role of nanofluids to enhance the productivity and energy utilization efficiency of the solar stills. Specifically, the mechanism of energy transfer between the nanoparticles and the base fluid. This includes both plasmonic and thermal effects. It is evident that nanofluid utilization in small fraction enhanced the thermal conductivity compared to base fluid alone. Alumina was found to be the most suitable nanoparticle used as nanofluid inside the solar stills due to its availability and lower cost. Still, other competitors such as carbon nanostructures need to be investigated as it provides higher enhancement of thermal conductivity. Also, several aspects of energy utilization enhancement have been discussed, including innovative application techniques. The challenges of such integrated systems are addressed as well.

Environmental impacts of solar energy systems: A review.

The annual increases in global energy consumption, along with its environmental issues and concerns, are playing significant roles in the massive sustainable and renewable global transmission of energy. Solar energy systems have been grabbing most attention among all the other renewable energy systems throughout the last decade. However, even renewable energies can have some adverse environmental repercussions; therefore, further attention and proper precautional procedures should be given. This paper discusses in detail the environmental impacts of several commercial and emerging solar energy systems at both small- and utility-scales. The study expands to some of the related advances, as well as some of the essential elements in their systems. The approach follows all the stages, starting with the designs, then throughout their manufacturing, materials, construction or installation phases, and over operation lifetime and decommissioning. Specific solutions for most systems such as waste minimization and recycling are discussed, alongside with some technically and ecologically favorable recommendations for mitigating the impacts.