75 research outputs found
The Aims of the Criminal Law
Cu2ZnSnS4(CZTS) is an interesting material for sustainable photovoltaics, but efficiencies are limitedby the low open-circuit voltage. A possible cause of this is disorder among the Cu and Zn cations, aphenomenon which is difficult to detect by standard techniques. We show that this issue can beovercome using near-resonant Raman scattering, which lets us estimate a critical temperature of 533±10 K for the transition between ordered and disordered CZTS. These findings have deepsignificance for the synthesis of high-quality material, and pave the way for quantitative investigationof the impact of disorder on the performance of CZTS-based solar cells.kestCa
Surfactant-free CZTS nanoparticles as building blocks for low-cost solar cell absorbers
A process route for the fabrication of solvent-redispersible, surfactant-free Cu2ZnSnS4 (CZTS) nanoparticles has been designed with the objective to have the benefit of a simple sulfide source which advantageously acts as (i) a complexing agent inhibiting crystallite growth, (ii) a surface additive providing redispersion in low ionic strength polar solvents and (iii) a transient ligand easily replaced by an carbon-free surface additive. This multifunctional use of the sulfide source has been achieved through a fine tuning of((Cu2+)a(Zn2+)b(Sn4+)c(Tu)d(OH?)e)t+, Tu = thiourea) oligomers, leading after temperature polycondensation and S2- exchange to highly concentrated (c > 100 g l-1), stable, ethanolic CZTS dispersions. The good electronic properties and low-defect concentration of the sintered, crack-free CZTSe films resulting from these building blocks was shown by photoluminescence investigation, making these building blocks interesting for low-cost, high-performance CZTSe solar cells
Surfactant-free CZTS nanoparticles as building blocks for low-cost solar cell absorbers
A process route for the fabrication of solvent-redispersible, surfactant-free Cu2ZnSnS4 (CZTS) nanoparticles has been designed with the objective to have the benefit of a simple sulfide source which advantageously acts as (i) a complexing agent inhibiting crystallite growth, (ii) a surface additive providing redispersion in low ionic strength polar solvents and (iii) a transient ligand easily replaced by an carbon-free surface additive. This multifunctional use of the sulfide source has been achieved through a fine tuning of((Cu2+)a(Zn2+)b(Sn4+)c(Tu)d(OH?)e)t+, Tu = thiourea) oligomers, leading after temperature polycondensation and S2- exchange to highly concentrated (c > 100 g l-1), stable, ethanolic CZTS dispersions. The good electronic properties and low-defect concentration of the sintered, crack-free CZTSe films resulting from these building blocks was shown by photoluminescence investigation, making these building blocks interesting for low-cost, high-performance CZTSe solar cells
Effi cacy of a Russian-backbone live attenuated infl uenza vaccine among children in Senegal: a randomised, double-blind, placebo-controlled trial
Background Live attenuated infl uenza vaccines have been shown to signifi cantly reduce infl uenza in diverse
populations of children, but no effi cacy studies have been done in resource-poor tropical settings. In Senegal, we
assessed the effi cacy and safety of a live attenuated infl uenza vaccine based on Russian-derived master donor viruses
and licensed as a single dose.
Methods In this double-blind, placebo-controlled, parallel group, single-centre trial done near Niakhar, Senegal,
generally healthy children aged 2–5 years were randomly allocated (2:1) to receive a single intranasal dose of masked
trivalent live attenuated infl uenza vaccine or placebo. The allocation sequence was computer-generated by PATH with
block sizes of three. The manufacturer provided vaccine and placebo in coded vials to preserve blinding. Participants
were monitored through the predictable infl uenza season in Senegal for adverse events and signs and symptoms of
infl uenza using weekly home visits and surveillance in clinics. The primary outcome was symptomatic laboratoryconfi
rmed infl uenza caused by any strain and occurring from 15 days post-vaccination to the end of the study. The
primary analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT01854632.
Findings Between May 23, and July 1, 2013, 1761 children were randomly assigned, 1174 to receive live attenuated
infl uenza vaccine and 587 to receive placebo. The per-protocol set included 1173 vaccinees and 584 placebo recipients
followed up to Dec 20, 2013. Symptomatic infl uenza was laboratory-confi rmed in 210 (18%) of 1173 recipients of live
attenuated infl uenza vaccine and 105 (18%) of placebo recipients, giving a vaccine effi cacy of 0·0% (95% CI –26·4 to 20·9).
Adverse events were balanced between the study groups. Two girls who had received live attenuated infl uenza vaccine
died, one due to anasarca 12 days postvaccination and one due to malnutrition 70 days postvaccination.
Interpretation Live attenuated infl uenza vaccine was well tolerated in young children in Senegal, but did not provide
protection against infl uenza. Further study in such populations, which might experience extended periods of
infl uenza circulation, is warranted
Who interacts with whom?:Social mixing insights from a rural population in India
Acute lower respiratory infections (ALRI) are a leading cause of morbidity and mortality globally, with most ALRI deaths occurring in children in developing countries. Computational models can be used to test the efficacy of respiratory infection prevention interventions, but require data on social mixing patterns, which are sparse in developing countries. We describe social mixing patterns among a rural community in northern India. During October 2015-February 2016, trained field workers conducted cross-sectional face-to-face standardized surveys in a convenience sample of 330 households in Faridabad District, Haryana State, India. Respondents were asked about the number, duration, and setting of social interactions during the previous 24 hours. Responses were compared by age and gender. Among the 3083 residents who were approached, 2943 (96%) participated, of whom 51% were male and the median age was 22 years (interquartile range (IQR) 9-37). Respondents reported contact (defined as having had a face-to-face conversation within 3 feet, which may or may not have included physical contact) with a median of 17 (IQR 12-25) people during the preceding 24 hours. Median total contact time per person was 36 person-hours (IQR 26-52). Female older children and adults had significantly fewer contacts than males of similar age (Kruskal-Wallis χ2 = 226.59, p<0.001), but spent a longer duration in contact with young children (Kruskal-Wallis χ2 = 27.26, p<0.001), suggesting a potentially complex pattern of differential risk of infection between genders. After controlling for household size and day of the week, respondent age was significantly associated with number and duration of contacts. These findings can be used to model the impact of interventions to reduce lower respiratory tract infections in India
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