•Thermal model of a PV module from both energy and exergy viewpoints.•Brief review on the impact of temperature rise on PV module performance.•Comprehensive overview on recently developed PV module ...cooling technologies.•Passive cooling technologies including the use of phase change material.•Future countenance in PV cooling research.
Photovoltaic (PV) systems operate in a paradox; sunlight is the essential input to generate electricity with PV, but they suffer a digression in performance as the operating temperature goes higher. This work is a comprehensive compilation and review of the latest literature regarding research works rendered to achieve improved efficiency through appropriate cooling systems. Most of the research goals were twofold, that is to enhance the efficiency of the solar PV systems and to ensure a longer life at the same time. The passive cooling systems are found to achieve a reduction in PV module temperature in the range of 6–20°C with an improvement in electrical efficiency up to 15.5% maximum. On the other side, active cooling systems’ performance are better, as may expected, with a reduction in PV module temperature as high as 30°C with an improvement in electrical efficiency up to 22% maximum along with additional thermal energy output with efficiency reaching as high as 60%. Based on the wide-ranging review, it may be predicted that with the swelling growth of solar PV electricity worldwide, the compatible cooling system is becoming obligatory in order to ensure better energy harvest and utilization.
Global energy demand and environmental concerns are the driving force for use of alternative, sustainable, and clean energy sources. Solar energy is the inexhaustible and CO2-emission-free energy ...source worldwide. The Sun provides 1.4×105TW power as received on the surface of the Earth and about 3.6×104TW of this power is usable. In 2012, world power consumption was 17TW, which is less than 3.6×104TW. Photovoltaic (PV) cells are the basic element for converting solar energy into electricity. PV cell technologies, energy conversion efficiency, economic analysis, energy policies, environmental impact, various applications, prospects, and progress have been comprehensively reviewed and presented in this paper. This work compiles the latest literature (i.e. journal articles, conference proceedings, and reports, among others) on PV power generation, economic analysis, environmental impact, and policies to increase public awareness. From the review, it was found that PV is an easy way to capture solar energy where PV based power generation has also rapidly increased.
•Land cover should not be considered as a static parameter in susceptibility analysis.•Changes in land cover pattern lead to modification in landslide spatial probability.•Simulated land cover ...scenarios for assessing future landslide susceptibility.•Information obtained can be helpful for land management and planning actions.
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Land cover is one of the most important conditioning factors in landslide susceptibility analysis. Usually it is considered as a static factor, but it has proven to be dynamic, with changes occurring even in few decades. In this work the influence of land cover changes on landslide susceptibility are analyzed for the past and for future scenarios. For the application, an area representative of the hilly-low mountain sectors of the Italian Southern Apennines was chosen (Rivo basin, in Molise Region). With this purpose landslide inventories and land cover maps were produced for the years 1954, 1981 and 2007. Two alternative future scenarios were created for 2050, one which follows the past trend (2050-trend), and another one more extreme, foreseeing a decrease of forested and cultivated areas (2050-alternative). The landslide susceptibility analysis was performed using the Spatial Multi-Criteria Evaluation method for different time steps, investigating changes to susceptibility over time.
The results show that environmental dynamics, such as land cover change, affect slope stability in time. In fact there is a decrease of susceptibility in the past and in the future 2050-trend scenario. This is due to the increase of forest or cultivated areas, that is probably determined by a better land management, water and soil control respect to other land cover types such as shrubland, pasture or bareland. Conversely the results revealed by the alternative scenario (2050-alternative), show how the decrease in forest and cultivated areas leads to an increase in landslide susceptibility. This can be related to the assumed worst climatic condition leading to a minor agricultural activity and lower extension of forested areas, possibly associated also to the effects of forest fires. The results suggest that conscious landscape management might contribute to determine a significant reduction in landslide susceptibility.
Wide-neck bifurcating aneurysms are increasingly treated with intracranial stent-assisted coiling by using shape-memory alloy microstents. We sought to investigate the short- and long-term effects of ...intracranial stent implantation on the geometry and angular conformation of the stent-coiled vascular bifurcation.
Thirty patients underwent stent-mediated coiling for 31 bifurcation aneurysms by using 31 self-expanding Neuroform (n = 14) and Enterprise (n = 17) stents (17 women; mean age, 56 years). The angle (δ) between the stented mother and daughter vessels at the bifurcation was measured by using multiplanar imaging of reconstructed rotational conventional angiography volumes and was compared by using matched-pair statistics. Neuroform and Enterprise longitudinal stent stiffness was measured in vitro at an increasing bending angle θ (θ = 180°-δ).
Stent deployment increased the bifurcation angle δ from 101.5° to 119.8° postprocedurally and to 137.3° (P < .0001) at latest follow-up, resulting in effective straightening; the angular remodeling was greater in distal-versus-proximal arteries (anterior cerebral > MCA > BA > ICA), inversely proportional to mother-vessel diameter and proportional to pretreatment bending angle θ. At follow-up, angle δ continued to significantly expand, with remodeling being greater in the early period (1-6 versus >7 months) and more pronounced with the longitudinally stiffer closed-cell Enterprise compared with the open-cell Neuroform stent.
Stent placement across bifurcation aneurysms leads to a significant biphasic angular remodeling related to stent type and vessel caliber, altering morphology to mimic sidewall lesions, a phenomenon needing consideration during procedural planning. Future work is needed to uncover the hemodynamic implications of this structural change and any possible effect on aneurysm-recurrence rates.
Date palms (Phoenix dactylifera) are the most significant perennial crop in arid regions of the Middle East and North Africa. Here, we present a comprehensive catalogue of approximately seven million ...single nucleotide polymorphisms in date palms based on whole genome re-sequencing of a collection of 62 cultivars. Population structure analysis indicates a major genetic divide between North Africa and the Middle East/South Asian date palms, with evidence of admixture in cultivars from Egypt and Sudan. Genome-wide scans for selection suggest at least 56 genomic regions associated with selective sweeps that may underlie geographic adaptation. We report candidate mutations for trait variation, including nonsense polymorphisms and presence/absence variation in gene content in pathways for key agronomic traits. We also identify a copia-like retrotransposon insertion polymorphism in the R2R3 myb-like orthologue of the oil palm virescens gene associated with fruit colour variation. This analysis documents patterns of post-domestication diversification and provides a genomic resource for this economically important perennial tree crop.
•Minimum strain/stress of highly c-axis oriented ZnO was grown at suitable thermal annealing (Ta) temperature.•The ZnO crystal orientation was influenced by strain/stress of the film.•Minimum ...stress/strain of ZnO film leads to lower defects.•Bandgap and defects were closely intertwined with strain/stress.•We report additional optical and electrical properties based on thermal annealing (Ta) temperature.
Nanocrystalline zinc oxide (ZnO) thin films have been deposited on glass substrates using a sonicated sol–gel dip-coating technique at various thermal annealing (Ta) temperatures. The Ta temperature was varied to range from 300 to 600°C in intervals of 50°C in an open atmosphere. To obtain desirable piezoelectric properties, the correlations between Ta and the characteristics of ZnO thin films (crystallisation, optical and electrical behaviour) were investigated. The as-deposited films have large compressive stresses of 0.49GPa, which relaxed to 0.27GPa as the Ta temperature increased to 500°C. Optical parameters, such as optical transmittance, absorption coefficient and energy band gap, have been studied and discussed with respect to Ta. All films exhibit a transmittance above 50% in the visible region. It was found that the compressive stresses in the films cause a decrease in the optical band gap, whereas the tensile stress reveals an incline pattern with the optical band gap. This result corroborated with the crystallinity along the c-axis plane. The highest crystallinity value was achieved at the lowest stress value. An identical trend was observed for the resistivity values from the I–V measurement. Moreover, an increase in the crystallite size from 10 to 39nm as the level of Ta increased was noticed. The thickness of the films also decreased when Ta increased, and denser films were obtained as a result. A qualified ZnO thin film with good piezoelectric properties has been prepared using a sonicated sol–gel dip-coating technique with various Ta. Experimental results show that Ta has the greatest influence on the final properties of the ZnO thin films.
•Minimum stress of highly c-axis oriented ZnO was grown at suitable deposition speed.•The ZnO crystal orientation was influenced by strain/stress of the film.•Minimum stress/strain of ZnO film leads ...to lower defects.•Bandgap and defects were closely intertwined with strain/stress.•We report additional optical and electrical properties based on deposition speed.
Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposition speeds by a sonicated sol–gel dip-coating technique. This work studies the effects of deposition speed on the crystallisation behaviour and optical and electrical properties of the resulting films. X-ray diffraction (XRD) analysis showed that thin films were preferentially oriented along the (002) c-axis direction of the crystal. The transformation sequence of strain and stress effects in ZnO thin films has also been studied. The films deposited at a low deposition speed exhibited a large compressive stress of 0.78GPa, which decreased to 0.43GPa as the deposition speed increased to 40mm/min. Interestingly, the enhancement in the crystallinity of these films led to a significant reduction in compressive stress. All films exhibited an average transmittance of greater than 90% in the visible region, with absorption edges at ∼380nm. The photoluminescence (PL) measurements indicated that the intensity of the emission peaks varied significantly with deposition speed. The optical band gap energy (Eg) was evaluated as 3.276–3.289eV, which increased with decreasing compressive stress along the c-axis. The energy band gap of the resulting ZnO films was found to be strongly influenced by the preferred c-axis (002) orientation.
Background
Pediatric-onset SLE (pSLE) is a multisystem autoimmune disease. Recently, the ficolin-2 (FCN2) gene has emerged as a potential candidate gene for susceptibility to SLE.
Objectives
The ...objective of this study was to evaluate the association of the FCN2 gene polymorphisms at positions −986 (G/A), −602 (G/A), −4 (A/G) and SNP C/T (rs3124954) located in intron 1, with susceptibility to pSLE in Egyptian children and adolescents.
Methods
This was a multicenter study of 280 patients diagnosed with pSLE, and 280 well-matched healthy controls. The FCN2 promoter polymorphisms at –986 G/A (rs3124952), −602 G/A (rs3124953), −4 A/G (rs17514136) and SNP C/T (rs3124954) located in intron 1 were genotyped by polymerase chain reaction, while serum ficolin-2 levels were assessed using enzyme-linked immunosorbent assay.
Results
The frequencies of the FCN2 GG genotype and G allele at −986 and −602 positions were significantly more represented in patients with pSLE than in controls (p < 0.001). Conversely, the FCN2 AA genotype and A allele at position −4 were more common in patients than in controls (p < 0.001). Moreover, patients carrying the FCN2 GG genotype in −986 position were more likely to develop lupus nephritis (odds ratio: 2.6 (95% confidence interval: 1.4–4.78); p = 0.006). The FCN2 AA genotype at position −4 was also identified as a possible risk factor for lupus nephritis (odds ratio: 3.12 (95% confidence interval: 1.25–7.84); p = 0.024).
Conclusion
The FCN2 promoter polymorphisms may contribute to susceptibility to pSLE in Egyptian children and adolescents. Moreover, the FCN2 GG genotype at position −986 and AA genotype at position −4 were associated with low serum ficolin-2 levels and may constitute risk factors for lupus nephritis in pSLE.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Summary Background Diffuse large-B-cell lymphoma is curable, but when treatment fails, outcome is poor. Although imaging can help to identify patients at risk of treatment failure, they are often ...imprecise, and radiation exposure is a potential health risk. We aimed to assess whether circulating tumour DNA encoding the clonal immunoglobulin gene sequence could be detected in the serum of patients with diffuse large-B-cell lymphoma and used to predict clinical disease recurrence after frontline treatment. Methods We used next-generation DNA sequencing to retrospectively analyse cell-free circulating tumour DNA in patients assigned to one of three treatment protocols between May 8, 1993, and June 6, 2013. Eligible patients had diffuse large-B-cell lymphoma, no evidence of indolent lymphoma, and were previously untreated. We obtained serial serum samples and concurrent CT scans at specified times during most treatment cycles and up to 5 years of follow-up. VDJ gene segments of the rearranged immunoglobulin receptor genes were amplified and sequenced from pretreatment specimens and serum circulating tumour DNA encoding the VDJ rearrangements was quantitated. Findings Tumour clonotypes were identified in pretreatment specimens from 126 patients who were followed up for a median of 11 years (IQR 6·8–14·2). Interim monitoring of circulating tumour DNA at the end of two treatment cycles in 108 patients showed a 5-year time to progression of 41·7% (95% CI 22·2–60·1) in patients with detectable circulating tumour DNA and 80·2% (69·6–87·3) in those without detectable circulating tumour DNA (p<0·0001). Detectable interim circulating tumour DNA had a positive predictive value of 62·5% (95% CI 40·6–81·2) and a negative predictive value of 79·8% (69·6–87·8). Surveillance monitoring of circulating tumour DNA was done in 107 patients who achieved complete remission. A Cox proportional hazards model showed that the hazard ratio for clinical disease progression was 228 (95% CI 51–1022) for patients who developed detectable circulating tumour DNA during surveillance compared with patients with undetectable circulating tumour DNA (p<0·0001). Surveillance circulating tumour DNA had a positive predictive value of 88·2% (95% CI 63·6–98·5) and a negative predictive value of 97·8% (92·2–99·7) and identified risk of recurrence at a median of 3·5 months (range 0–200) before evidence of clinical disease. Interpretation Surveillance circulating tumour DNA identifies patients at risk of recurrence before clinical evidence of disease in most patients and results in a reduced disease burden at relapse. Interim circulating tumour DNA is a promising biomarker to identify patients at high risk of treatment failure. Funding National Cancer Institute and Adaptive Biotechnologies.
Although the therapeutic benefit of proteasome inhibition in multiple myeloma remains unchallenged, drug resistance inevitably emerges through mechanisms that remain elusive. Bortezomib provokes ...unwanted protein accumulation and the endoplasmic reticulum stress to activate the unfolded protein response (UPR) and autophagy as compensatory mechanisms that restore protein homeostasis. High-throughput screens to detect pharmacologics that modulated autophagy to enhance the anti-myeloma effect of bortezomib revealed metformin, a widely used antidiabetic agent with proven efficacy and limited adverse effects. Metformin co-treatment with bortezomib suppressed induction of the critical UPR effector glucose-regulated protein 78 (GRP78) to impair autophagosome formation and enhance apoptosis. Gene expression profiling of newly diagnosed myeloma patient tumors further correlated the hyperexpression of GRP78-encoding HSPA5 with reduced clinical response to bortezomib. The effect of bortezomib was enhanced with metformin co-treatment using myeloma patient tumor cells and the chemoresistant, stem cell-like side population that may contribute to disease recurrence. The relevance of the findings was confirmed in vivo as shown by metformin co-treatment with bortezomib that delayed the growth of myeloma xenotransplants. Taken together, our results suggest that metformin suppresses GRP78, a key driver of bortezomib-induced autophagy, and support the pharmacologic repositioning of metformin to enhance the anti-myeloma benefit of bortezomib.
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