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- Mishra, A, et al.
(författare)
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Diminishing benefits of urban living for children and adolescents' growth and development
- 2023
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 615:7954, s. 874-883
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Tidskriftsartikel (refereegranskat)abstract
- Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified.
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| 2. |
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| 3. |
- Lin, Na, 1981-
(författare)
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Theoretical Studies on Electronic and Vibrationally Resolved Multi-Photon Absorption and Dichroism
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents time-dependent density functional theory studies on electronic and vibronically resolved linear and nonlinear optical absorption and dichroism spectra of organic molecules. Special attention has been paid to the influence of solvent environment and molecular vibrations on one-, two- and three-photon absorption and one- and two-photon circular dichroism. It is found that dielectric medium as described by polarizable continuum model can enhance remarkably three-photon absorption cross section of a highly conjugated fluorene derivative, for which the simplified two-state model is shown to be largely inadequate. Origin-invariant density functional calculations on one- and two-photon circular dichroisms of a chiral molecule confirm that the recently developed CAMB3LYP functional performs better than the popular B3LYP functional for Rydberg-states. The first experimental measurement of TPCD spectra is performed on an axial chiral system in tetrahydrofunan, where the double L-scan technique is applied. Theoretical calculations well reproduce the experimental profiles when both the electron correlation and the solvent effect are taken into account. Vibronically resolved one- and two-photon absorption spectra of charge-transfer molecules have been obtained using a Linear Coupling model, where the 'borrowing mechanism' for the so-called Herzberg-Teller contribution is analyzed in detail. It is shown that Herzberg-Teller contribution can introduce a change of sign to the chiral responses of a molecule without the involvement of different electronic states, which has important consequences for the assignment of absolute configurations of chiral molecules. Adiabatic harmonic Franck-Condon model is also applied to simulate vibronically resolved one- and two-photon circular dichroism spectra of the same chiral system, where the sign-inversion and the interference between Franck-Condon and Herzberg-Teller contributions are also observed.
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| 4. |
- Zhang, Liang, et al.
(författare)
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Deep Learning for Additive Screening in Perovskite Light-Emitting Diodes
- 2022
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 61:37
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Tidskriftsartikel (refereegranskat)abstract
- Additive engineering with organic molecules is of critical importance for achieving high-performance perovskite optoelectronic devices. However, experimentally finding suitable additives is costly and time consuming, while conventional machine learning (ML) is difficult to predict accurately due to the limited experimental data available in this relatively new field. Here, we demonstrate a deep learning method that can predict the effectiveness of additives in perovskite light-emitting diodes (PeLEDs) with a high accuracy up to 96 % by using a small dataset of 132 molecules. This model can maximize the information of the molecules and significantly mitigate the duplicated problem that usually happened with previous models in ML for molecular screening. Very high efficiency PeLEDs with a peak external quantum efficiency up to 22.7 % can be achieved by using the predicated additive. Our work opens a new avenue for further boosting the performance of perovskite optoelectronic devices.
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