136 research outputs found

    Interface engineering for perovskite solar cells based on 2d‐materials: A physics point of view

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    The last decade has witnessed the advance of metal halide perovskites as a promising low-cost and efficient class of light harvesters used in solar cells (SCs). Remarkably, the efficiency of lab-scale perovskite solar cells (PSCs) reached a power conversion efficiency of 25.5% in just similar to 10 years of research, rivalling the current record of 26.1% for Si-based PVs. To further boost the performances of PSCs, the use of 2D materials (such as graphene, transition metal dichalcogenides and transition metal carbides, nitrides and carbonitrides) has been proposed, thanks to their remarkable optoelectronic properties (that can be tuned with proper chemical composition engineering) and chemical stability. In particular, 2D materials have been demonstrated as promising candidates for (i) accelerating hot carrier transfer across the interfaces between the perovskite and the charge extraction layers; (ii) improving the crystallization of the perovskite layers (when used as additives in the precursor solution); (iii) favoring electronic bands alignment through tuning of the work function. In this mini-review, we discuss the physical mechanisms underlying the increased efficiency of 2D material-based PSCs, focusing on the three aforementioned effects

    Advances in Perovskites for Photovoltaic Applications in Space

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    Perovskites have emerged as promising light harvesters in photovoltaics. The resulting solar cells (i) are thin and lightweight, (ii) can be produced through solution processes, (iii) mainly use low-cost raw materials, and (iv) can be flexible. These features make perovskite solar cells intriguing as space technologies; however, the extra-terrestrial environment can easily cause the premature failure of devices. In particular, the presence of highenergy radiation is the most dangerous factor that can damage space technologies. This Review discusses the status and perspectives of perovskite photovoltaics in space applications. The main factors used to describe the space environment are introduced, and the results concerning the radiation hardness of perovskites toward protons, electrons, neutrons, and gamma-rays are presented. Emphasis is given to the physicochemical processes underlying radiation damage in such materials. Finally, the potential use of perovskite solar cells in extra-terrestrial conditions is discussed by considering the effects of the space environment on the choice of the architecture and components of the devices

    Solar Energy in Space Applications: Review and Technology Perspectives

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    Solar cells (SCs) are the most ubiquitous and reliable energy generation systems for aerospace applications. Nowadays, III-V multijunction solar cells (MJSCs) represent the standard commercial technology for powering spacecraft, thanks to their high-power conversion efficiency and certified reliability/stability while operating in orbit. Nevertheless, spacecraft companies are still using cheaper Si-based SCs to amortize the launching costs of satellites. Moreover, in recent years, new SCs technologies based on Cu(In,Ga)Se-2 (CIGS) and perovskite solar cells (PSCs) have emerged as promising candidates for aerospace power systems, because of their appealing properties such as lightweightness, flexibility, cost-effective manufacturing, and exceptional radiation resistance. In this review the current advancements and future challenges of SCs for aerospace applications are critically discussed. In particular, for each type of SC, a description of the device's architecture, a summary of its performance, and a quantitative assessment of the radiation resistance are presented. Finally, considering the high potential that 2D-materials (such as graphene, transition metal dichalcogenides, and transition metal carbides, nitrides, and carbonitrides) have in improving both performance and stability of SCs, a brief overview of some important results concerning the influence of radiation on both 2D materials-based devices and monolayer of 2D materials is also included

    Evaluation of Different Adiposity Indices and Association with Metabolic Syndrome Risk in Obese Children: Is there a Winner?

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    Body shape index (ABSI) and triponderal mass index (TMI) have been recently associated with cardiovascular risk in adults. A cross-sectional study was conducted to evaluate the relationship between different anthropometric adiposity indexes and metabolic syndrome (MetS) in Caucasian obese children and adolescents. Consecutive obese children aged 657 years have been enrolled. Anthropometric parameters, body composition (by bioelectrical impedance), and systolic and diastolic blood pressure have been measured. Fasting blood samples have been analyzed for lipids, insulin, glucose. A multivariate logistic regression analyses, with body mass index z-score, waist to height ratio, ABSI z-score, TMI, conicity index as predictors for MetS (IDEFICS and IDF criteria according to age) has been performed. Four hundred and three (179 boys and 224 girls) obese children, aged 7\u201320 years, have been evaluated. When we explored the joint contribution of each anthropometric and adiposity index of interest and BMIz on the risk of MetS, we found that the inclusion of ABSIz improved the prediction of MetS compared to BMIz alone. ABSI-BMI can be a useful index for evaluating the relative contribution of central obesity to cardiometabolic risk in clinical management of obese children and adolescents

    Nutritional management and follow up of infants and children with food allergy: Italian Society of Pediatric Nutrition/Italian Society of Pediatric Allergy and Immunology Task Force Position Statement.

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    Although the guidelines on the diagnosis and treatment of food allergy recognize the role of nutrition, there is few literature on the practical issues concerning the nutritional management of children with food allergies. This Consensus Position Statement focuses on the nutritional management and follow-up of infants and children with food allergy.It provides practical advices for the management of children on exclusion diet and it represents an evidence-based consensus on nutritional intervention and follow-up of infants and children with food allergy. Children with food allergies have poor growth compared to non-affected subjects directly proportional to the quantity of foods excluded and the duration of the diet. Nutritional intervention, if properly planned and properly monitored, has proven to be an effective mean to substantiate a recovery in growth. Nutritional intervention depends on the subject's nutritional status at the time of the diagnosis. The assessment of the nutritional status of children with food allergies should follow a diagnostic pathway that involves a series of successive steps, beginning from the collection of a detailed diet-history. It is essential that children following an exclusion diet are followed up regularly. The periodic re-evaluation of the child is needed to assess the nutritional needs, changing with the age, and the compliance to the diet. The follow- up plan should be established on the basis of the age of the child and following the growth pattern

    Change in metabolic profile after 1-year nutritional-behavioral intervention in obese children

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    Research findings are inconsistent about improvement of specific cardio-metabolic variables after lifestyle intervention in obese children. The aim of this trial was to evaluate the effect of a 1-year intervention, based on normocaloric diet and physical activity, on body mass index (BMI), blood lipid profile, glucose metabolism and metabolic syndrome. Eighty-five obese children aged 656 years were analyzed. The BMI z-score was calculated. Fasting blood samples were analyzed for lipids, insulin and glucose. The homeostatic model assessment of insulin resistance (HOMA-IR) was calculated and insulin resistance was defined as HOMA-IR >3.16. HOMA-\u3b2%, quantitative insulin sensitivity check index and triglyceride glucose index were calculated. The metabolic syndrome was defined in accordance with the International Diabetes Federation criteria. At the end of intervention children showed a reduction (mean (95% CI)) in BMI z-score ( 120.58 ( 120.66; 120.50)), triglycerides ( 120.35 ( 120.45; 120.25) mmol/L) and triglyceride glucose index ( 120.29 ( 120.37; 120.21)), and an increase in HDL cholesterol (0.06 (0.01; 0.11) mmol/L). Prevalence of insulin resistance declined from 51.8% to 36.5% and prevalence of metabolic syndrome from 17.1% to 4.9%. Nutritional-behavioral interventions can improve the blood lipid profile and insulin sensitivity in obese children, and possibly provide benefits in terms of metabolic syndrome

    The effect of different formulas in children with cow ' s milk allergy on the occurrence of other allergic manifestations and the time of immune tolerance acquisition: The atopic march II study

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    Background : Recent data suggest that the use of extensively hydrolyzed casein formula containing the probiotic L.rhamnosus GG (LGG) (EHCF+LGG) reduces the incidence of other AMs and hastens the development of immune tolerance in children with IgE- mediated cow ' s milk allergy (CMA). To see whether formula choice for CMA treatment could impact the occurrence of other AMs and the time of immune tolerance acquisition. Method : Prospective open non- randomized trial on a cohort of children with a diagnosis of IgE- mediated CMA in the first year of life, already in follow- up. The patients were treated with one of the following formulas: EHCF+LGG, rice hydrolyzed formula (RHF), soy formula (SF), extensively hydrolyzed whey formula (EHWF) or amino- acid based formula (AAF). All subjects were evaluated during a 36 months follow- up. The occurence of AMs (atopic eczema, allergic urticaria, asthma and oculorhinitis) was diagnosed Immune tolerance acquisition was evaluated every 12 month by the result of oral food challenge. Results : A total of 365 subjects completed the study, 73 per group. All children were from families of middle socio- economic status and lived in urban areas. At enrollment, all subjects were in stable clinical conditions without symptoms related to CMA. Demographic and anamnestic features were similar comparing the study cohorts at enrolment. Binomial regression revealed that the estimates of the incidence of the AMs are: EHCF+LGG: 0.22 (Bonferroni corrected 95%CI: 0.09 to 0.34); RHF: 0.52 (Bonferroni corrected 95%CI: 0.37 to 0.67); SF: 0.58 (Bonferroni corrected 95%CI: 0.43 to 0.72); EHWF : 0.51 (Bonferroni corrected 95%CI: 0.36 to 0.66); AAF: 0.77 (Bonferroni corrected 95%CI: 0.64 to 0.89). The incidence of the main outcome in the RHF, SF, EHWF and AAF groups vs the EHCF+LGG group was always higher than the pre- specified absolute difference of 0.25 and significantly higher at the pre- specified alphalevel of 0.0125 ( P - value <= 0.001 in all cases). The acquisition of immune tolerance was significantly higher in the EHCF+LGG group comparing to the other groups. The rate of immune tolerance acquisition for EHCF+LGG groups was (95%CI): at 12 months = 0.41 (0.30 to 0.52); at 24 months = 0.64 (0.53 to 0.75); at 36 months = 0.81 (0.72 to 0.90). Conclusion : The results of the study suggest that EHCF+LGG is superior to other formulas for the prevention of AMs and for the acquisition of immune tolerance in children with CMA

    Palm Oil and Beta-palmitate in Infant Formula: A Position Paper by the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) Committee on Nutrition

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    Background: Palm oil (PO) is used in infant formulas in order to achieve palmitic acid (PA) levels similar to those in human milk. PA in PO is esterified predominantly at the SN-1,3 position of triacylglycerol (TAG), and infant formulas are now available in which a greater proportion of PA is in the SN-2 position (typical configuration in human milk). As there are some concerns about the use of PO, we aimed to review literature on health effects of PO and SN-2-palmitate in infant formulas. / Methods: PubMed and Cochrane Database of Systematic Reviews were systematically searched for relevant studies on possible beneficial effects or harms of either PO or SN-2-palmitate in infant formula on various health outcomes. / Results: We identified 12 relevant studies using PO and 21 studies using SN-2-palmitate. Published studies have variable methodology, subject characteristics, and some are underpowered for the key outcomes. PO is associated with harder stools and SN-2-palmitate use may lead to softer stool consistency. Bone effects seem to be short-lasting. For some outcomes (infant colic, faecal microbiota, lipid metabolism), the number of studies is very limited and summary evidence inconclusive. Growth of infants is not influenced. There are no studies published on the effect on markers of later diseases. / Conclusions: There is insufficient evidence to suggest that PO should be avoided as a source of fat in infant formulas for health reasons. Inclusion of high SN-2-palmitate fat blend in infant formulas may have short-term effects on stool consistency but cannot be considered essential

    Milk protein intake, the metabolic-endocrine response, and growth in infancy : data from a randomized clinical trial

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    BACKGROUND: Protein intake in early infancy has been suggested to be an important risk factor for later obesity, but information on potential mechanisms is very limited. OBJECTIVE: This study examined the influence of protein intake in infancy on serum amino acids, insulin, and the insulin-like growth factor I (IGF-I) axis and its possible relation to growth in the first 2 y of life. DESIGN: In a multicenter European study, 1138 healthy, formula-fed infants were randomly assigned to receive cow-milk-based infant and follow-on formulas with lower protein (LP; 1.77 and 2.2 g protein/100 kcal) or higher protein (HP; 2.9 and 4.4 g protein/100 kcal) contents for the first year. Biochemical variables were measured at age 6 mo in 339 infants receiving LP formula and 333 infants receiving HP formula and in 237 breastfed infants. RESULTS: Essential amino acids, especially branched-chain amino acids, IGF-I, and urinary C-peptide:creatinine ratio, were significantly (P < 0.001) higher in the HP group than in the LP group, whereas IGF-binding protein (IGF-BP) 2 was lower and IGF-BP3 did not differ significantly. The median IGF-I total serum concentration was 48.4 ng/mL (25th, 75th percentile: 27.2, 81.8 ng/mL) in the HP group and 34.7 ng/mL (17.7, 57.5 ng/mL) in the LP group; the urine C-peptide:creatinine ratios were 140.6 ng/mg (80.0, 203.8 ng/mg) and 107.3 ng/mg (65.2, 194.7 ng/mg), respectively. Most essential amino acids, IGF-I, C-peptide, and urea increased significantly in both the LP and HP groups compared with the breastfed group. Total IGF-I was significantly associated with growth until 6 mo but not thereafter. CONCLUSIONS: HP intake stimulates the IGF-I axis and insulin release in infancy. IGF-I enhances growth during the first 6 mo of life. This trial was registered at clinicaltrials.gov as NCT00338689
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