Updating the study protocol: Insight 46 - a longitudinal neuroscience sub-study of the MRC National Survey of Health and Development - phases 2 and 3.

BACKGROUND: Although age is the biggest known risk factor for dementia, there remains uncertainty about other factors over the life course that contribute to a person's risk for cognitive decline later in life. Furthermore, the pathological processes leading to dementia are not fully understood. The main goals of Insight 46-a multi-phase longitudinal observational study-are to collect detailed cognitive, neurological, physical, cardiovascular, and sensory data; to combine those data with genetic and life-course information collected from the MRC National Survey of Health and Development (NSHD; 1946 British birth cohort); and thereby contribute to a better understanding of healthy ageing and dementia. METHODS/DESIGN: Phase 1 of Insight 46 (2015-2018) involved the recruitment of 502 members of the NSHD (median age = 70.7 years; 49% female) and has been described in detail by Lane and Parker et al. 2017. The present paper describes phase 2 (2018-2021) and phase 3 (2021-ongoing). Of the 502 phase 1 study members who were invited to a phase 2 research visit, 413 were willing to return for a clinic visit in London and 29 participated in a remote research assessment due to COVID-19 restrictions. Phase 3 aims to recruit 250 study members who previously participated in both phases 1 and 2 of Insight 46 (providing a third data time point) and 500 additional members of the NSHD who have not previously participated in Insight 46. DISCUSSION: The NSHD is the oldest and longest continuously running British birth cohort. Members of the NSHD are now at a critical point in their lives for us to investigate successful ageing and key age-related brain morbidities. Data collected from Insight 46 have the potential to greatly contribute to and impact the field of healthy ageing and dementia by combining unique life course data with longitudinal multiparametric clinical, imaging, and biomarker measurements. Further protocol enhancements are planned, including in-home sleep measurements and the engagement of participants through remote online cognitive testing. Data collected are and will continue to be made available to the scientific community.

Biological/metal oxide composite transport layers cast from green solvents for boosting light harvesting response of organic photovoltaic cells indoors.

Organic solar cells with biological/metal-oxide electron transport layers (ETLs), consisting of a ZnO compact layer covered by a thin DNA layer, both of which deposited with green solvents (water or water/alcohols mixtures) are presented for application under low intensity indoor lighting. Under white LED lamp (200, 400 lx), photovoltaic cells with P3HT:PC70BM polymer semiconductor blends delivered an average maximum power density (MPD) of 8.7µW cm-2, corresponding to a power conversion efficiency, PCE, of = 8.56% (PCE of best cell was 8.74%). The ZnO/DNA bilayer boosted efficiency by 68% and 13% in relative terms compared to cells made with DNA-only and ZnO-only ETLs at 400 lx. Photovoltaic cells with ZnO/DNA composite ETLs based on PTB7:PC70BM blends, that absorb a broader range of the indoor lighting spectrum, delivered MPDs of 16.2µW cm-2with an estimated average PCE of 14.3% (best cell efficiency of 15.8%) at 400 lx. The best efficiencies for cells fabricated on flexible plastic substrates were 11.9% at 400 lx. This is the first report in which polymer photovoltaics incorporating biological materials have shown to increment performance at these low light levels and work very efficiently under indoor artificial light illumination. The finding can be useful for the production of more bio-compatible photovoltaics as well as bio-sensing devices based on organic semiconductors.

Luminescent Mechanochromism in a Gold(I)-Copper(I) N-Heterocyclic Carbene Complex.

The silver(I) species [Ag(benzim(CH2py)2)2]PF6 (1) was prepared by refluxing the ligand precursor [H(benzim(CH2py)2)2]PF6 with Ag2O and aqueous sodium hydroxide in dichloromethane. Simple transmetalation of 1 with tetrahydrothiophenegold(I) chloride forms the gold(I) analogue [Au(benzim(CH2py)2)2]PF6 (2). The addition of 2 equiv of [Cu(NCCH3)4]PF6 to 2 in acetonitrile produces a blue-luminescent, trimetallic complex, [AuCu2(benzim(CH2py)2)2(NCCH3)4](PF6)3·2CH3CN (3·2CH3CN). When blue-luminescent 3·2CH3CN is exposed to air, the complex loses four acetonitrile molecules, and the emission of the desolvated complex (4) appears aquamarine. Crystallization of 4 from different solvents produces the complexes [AuCu2(benzim(CH2py)2)2](PF6)3 (5) and [AuCu2(benzim(CH2py)2)2(NCCH2CH3)2](PF6)3 (6). Upon grinding, both 3·2CH3CN and 4 exhibit mechanochromic transformations to a yellow-luminescent powder (ground-4). The reversible mechanochromic transformation of 3·2CH3CN to ground-4 is a crystalline-to-amorphous conversion accompanied by partial desolvation. The luminescent mechanochromism of 4 to ground-4 is an "amorphous-to-amorphous" process and does not require solvent loss. In addition to their mechanochromic properties, both 3·2CH3CN and 4 exhibit luminescent thermochromism through desolvation to form a weak luminescent powder (7).

Solid state perovskite solar modules by vacuum-vapor assisted sequential deposition on Nd:YVO4 laser patterned rutile TiO2 nanorods.

The past few years have witnessed remarkable progress in solution-processed methylammonium lead halide (CH3NH3PbX3, X = halide) perovskite solar cells (PSCs) with reported photoconversion efficiency (η) exceeding 20% in laboratory-scale devices and reaching up to 13% in their large area perovskite solar modules (PSMs). These devices mostly employ mesoporous TiO2 nanoparticles (NPs) as an electron transport layer (ETL) which provides a scaffold on which the perovskite semiconductor can grow. However, limitations exist which are due to trap-limited electron transport and non-complete pore filling. Herein, we have employed TiO2 nanorods (NRs), a material offering a two-fold higher electronic mobility and higher pore-filing compared to their particle analogues, as an ETL. A crucial issue in NRs' patterning over substrates is resolved by using precise Nd:YVO4 laser ablation, and a champion device with η ∼ 8.1% is reported via a simple and low cost vacuum-vapor assisted sequential processing (V-VASP) of a CH3NH3PbI3 film. Our experiments showed a successful demonstration of NRs-based PSMs via the V-VASP technique which can be applied to fabricate large area modules with a pin-hole free, smooth and dense perovskite layer which is required to build high efficiency devices.

Neuropsychiatric scurvy.

BACKGROUND: Scurvy is a disease with well-known peripheral symptoms, such as bleeding and pain. METHODS: The clinical and historical evidence for a distinct form of scurvy affecting the central nervous system, called neuropsychiatric scurvy, is reviewed. Pathophysiologic factors are described, as well as its diagnosis and management.

Ascorbate- and zinc-responsive parkinsonism.

OBJECTIVE: To report a case of Parkinsonism rapidly responsive to intravenous replacement of vitamin C and zinc. CASE SUMMARY: A 66-year-old man with Parkinsonism, pleural effusion, and bipolar disorder was found to have low serum vitamin C and zinc levels. Intravenous replacement of these micronutrients led to resolution of the movement disorder in less than 24 hours. DISCUSSION: Parkinsonism has been associated with vitamin C deficiency, and recent cases of scurvy complicated by Parkinsonism have responded well to intravenous replacement of vitamin C. In this case, deficiency of zinc may have contributed to the development of a movement disorder. The likely pathophysiology of, and treatment recommendations for, Parkinsonism linked to deficiencies of vitamin C and zinc are reviewed. CONCLUSIONS: Whereas vitamin C has a strong link with Parkinsonism, the potential role of zinc has only been suspected. This case report highlights some of the potential links between zinc deficiency and Parkinsonism.

Effect of electrolyte bleaching on the stability and performance of dye solar cells.

Degradation of dye solar cells (DSCs) under severe ageing conditions may lead to loss of the tri-iodide in the electrolyte - a phenomenon known as electrolyte bleaching. Monitoring changes in the tri-iodide concentration as a result of degradation mechanisms and understanding their causes and effects are fundamental for improving the long-term stability of DSCs. In this contribution a strongly accelerated ageing test (1 Sun visible light, 1.5 Suns UV light, T = 110 °C for 12 h) was performed on DSCs in a double-sealed masterplate configuration to purposely induce severe electrolyte bleaching, and its effects on the performance and stability of DSCs with different initial tri-iodide concentrations [I3(-)]0 were investigated. The cells with low [I3(-)]0 suffered a severe loss in short circuit current density JSC (up to 85%). Also a significant loss of open circuit voltage VOC was observed and this loss was proportional to [I3(-)]0 with the highest VOC drop observed with the highest [I3(-)]0. Non-destructive analysis techniques based on the limited current density, JSCvs. light intensity, and photographic image analysis, were used to quantify the [I3(-)] loss, which was found to be ca. 50 mM and independent of [I3(-)]0. Quantitative model based VOC analysis in terms of changing [I3(-)] revealed that the degradation responsible for the VOC drop was dominated by an unknown mechanism that is unrelated to [I3(-)]0. The methods and results reported here help separating and identifying different degradation mechanisms related to electrolyte bleaching in DSCs.

Dispersion forces and counterintuitive steric effects in main group molecules: heavier group 14 (Si-Pb) dichalcogenolate carbene analogues with sub-90° interligand bond angles.

The synthesis and spectroscopic and structural characterization of an extensive series of acyclic, monomeric tetrylene dichalcogenolates of formula M(ChAr)2 (M = Si, Ge, Sn, Pb; Ch = O, S, or Se; Ar = bulky m-terphenyl ligand, including two new acyclic silylenes) are described. They were found to possess several unusual features-the most notable of which is their strong tendency to display acute interligand, Ch-M-Ch, bond angles that are often well below 90°. Furthermore, and contrary to normal steric expectations, the interligand angles were found to become narrower as the size of the ligand was increased. Experimental and structural data in conjunction with high-level DFT calculations, including corrections for dispersion effects, led to the conclusion that dispersion forces play an important role in stabilizing their acute interligand angles.

Interplay between transparency and efficiency in dye sensitized solar cells.

In this paper we analyze the interplay between transparency and efficiency in dye sensitized solar cells by varying fabrication parameters such as the thickness of the nano-crystalline TiO(2) layer, the dye loading and the dye type. Both transparency and efficiency show a saturation trend when plotted versus dye loading. By introducing the transparency-efficiency plot, we show that the relation between transparency and efficiency is linear and is almost independent on the TiO(2) thickness for a certain thickness range. On the contrary, the relation between transparency and efficiency depends strongly on the type of the dye. Moreover, we show that co-sensitization techniques can be effectively used to access regions of the transparency-efficiency space that are forbidden for single dye sensitization. The relation found between transparency and efficiency (T&E) can be the general guide for optimization of Dye Solar Cells in building integration applications.

Stable plumbylene dichalcogenolate monomers with large differences in their interligand angles and the synthesis and characterization of a monothiolato Pb(II) bromide and lithium trithiolato plumbate.

The complexes, Pb(ChAr(Pri4))2 (Ch = O (1), S (2); Ar(Pri4) = C6H3-2,6-(C6H3-2,6-Pr(i)2)2) were synthesized by alcoholysis and salt metathesis routes and represent the first fully characterized monomeric, two-coordinate, lead dichalcogenolates in the solid state. Structural studies showed that the S-Pb-S angle (77.21(4)°) is about 22° narrower than the corresponding O-Pb-O angle. (207)Pb NMR and electronic spectroscopy show that the separation between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) decreases from the bisaryloxo plumbylene to the bisthiolato derivative. Reaction of LiSAr(Me6) with PbBr2 in a 2:1 ratio led not to Pb(SAr(Me6))2, but to a mixture of the monothiolato lead(II) complex, {Pb(Br)(µ-SAr(Me6))}2 (3) and the lithium tristhiolato plumbate, LiPb(SAr(Me6))3 (4). 3 and 4 were isolated and purified by fractional recrystallization, and both were characterized by X-ray crystallography and spectroscopic studies.

Formulations and processing of nanocrystalline TiO2 films for the different requirements of plastic, metal and glass dye solar cell applications.

We carried out a systematic study on the effect of nanocrystalline TiO2 paste formulations and temperature treatment on the performance of dye solar cells (DSCs) over a large temperature range, to provide useful information for the fabrication of both plastic and metal flexible devices. We compared conventional screen-printable and binder-free TiO2 pastes with a new formulation which includes hydroxylethyl cellulose (HEC), enabling the study of the effect of organic materials in the TiO2 layer in the whole 25-600 °C temperature range. Differently from the binder-free formulations where the device efficiency rose monotonically with temperature, the use of cellulose binders led to remarkably different trends depending on their pyrolysis and decomposition thresholds and solubility, especially at those temperatures compatible with plastic foils. Above 325 °C, where metal foil can be used as substrates, the efficiencies become similar to those of the binder-free paste due to effective binder decomposition and inter-nanoparticle bonding. Finally, we demonstrated, for the first time, that the simultaneous application of both temperature (110-150 °C) and pressure (100 MPa) can lead to a large improvement (33%) compared to the same mechanical compression method carried out at room temperature only.

Green solvents, materials, and lead-free semiconductors for sustainable fabrication of perovskite solar cells.

Perovskite materials research has received unprecedented recognition due to its applications in photovoltaics, LEDs, and other large area low-cost electronics. The exceptional improvement in the photovoltaic conversion efficiency of Perovskite solar cells (PSCs) achieved over the last decade has prompted efforts to develop and optimize device fabrication technologies for the industrial and commercial space. However, unstable operation in outdoor environments and toxicity of the employed materials and solvents have hindered this proposition. While their optoelectronic properties are extensively studied, the environmental impacts of the materials and manufacturing methods require further attention. This review summarizes and discusses green and environment-friendly methods for fabricating PSCs, particularly non-toxic solvents, and lead-free alternatives. Greener solvent choices are surveyed for all the solar cell films, (i.e. electron and hole transport, semiconductor, and electrode layers) and their impact on thin film quality, morphology and device performance is explored. We also discuss lead content in perovskites, its environmental impact and sequestration routes, and progress in replacing lead with greener alternatives. This review provides an analysis of sustainable green routes in perovskite solar cell fabrication, discussing the impact of each layer in the device stack, via life cycle analysis.

Isolation of a stable, acyclic, two-coordinate silylene.

The synthesis and characterization of a stable, acyclic two-coordinate silylene, Si(SAr(Me(6)))(2) [Ar(Me(6)) = C(6)H(3)-2,6(C(6)H(2)-2,4,6-Me(3))(2)], by reduction of Br(2)Si(SAr(Me(6)))(2) with a magnesium(I) reductant is described. It features a V-shaped silicon coordination with a S-Si-S angle of 90.52(2)° and an average Si-S distance of 2.158(3) Å. Although it reacts readily with an alkyl halide, it does not react with hydrogen under ambient conditions, probably as a result of the ca. 4.3 eV energy difference between the frontier silicon lone pair and 3p orbitals.

Physical and electrochemical analysis of an indoor-outdoor ageing test of large-area dye solar cell devices.

A long-term life test (3200 h) on large-area dye-sensitized cells is performed both under outdoor conditions, in the sunny Mediterranean climate in Rome (Italy), and under continuous light soaking (1 Sun, 85 °C). Different degradation rates are investigated for the outdoor samples with horizontally and vertically oriented cells (azimuth South, tilt angle 25°). Thirty identical photocells (active area=3.6 cm(2), conversion efficiencies=(4.8±0.2)%) are aged using a robust master-plate configuration. After the first 1000 h of testing in open-circuit conditions, some of the test samples are set near the maximum power point (MPP) and the life test continued further until 3200 h. A detailed analysis of the physical parameters obtained by electrochemical impedance is given together with electrolyte transmittance variation with time as a function of the ageing conditions. Faster degradation in devices working at the MPP is observed, due mainly to a progressive decrease of the triiodide concentration in the electrolyte and a likely alteration at the titania/electrolyte interface. Outdoor devices working with vertically oriented cells show clearly that the orientation of long-striped cells can affect the lifetime. The aged cells suffer an increase of recombination rate, change in the chemical capacitance, and positive shift of the titania conduction band level. A strong correlation between the increase of the electrolyte diffusion resistance and degradation phenomena is found.

Electrochemistry in reverse biased dye solar cells and dye/electrolyte degradation mechanisms.

Mismatched or shadowed individual cells in a module can operate in the reverse bias (RB) regime. We investigate and identify key mechanisms for RB operation and degradation in dye solar cells (DSCs). Current-voltage characteristics in RB are sensitive to the type of dye utilised and to TiCl(4) substrate treatment. Subjecting the cell to a RB of 0.4 V over 740 h has little effect on conversion efficiency whereas a significant lowering is observed for the harsher stress tests at 0.6 V and by forcing a constant current equal to its I(SC). For more prolonged reverse biases at I(SC) (>740 h), we show that depletion of [I(3)(-)] inside the DSC can lead the reverse bias potentials across the cells to considerably increase in time. Electrochemical impedance measurements show that the overpotentials at the counter electrodes (CEs) can eventually reach values high enough to cause hydrogen evolution. Clear evidence of gas bubbles forming inside a complete dye solar cell under reverse bias stress, leading to severe device degradation, is presented. We also show that reactions of iodine with water present in the electrolyte can play an important role in [I(3)(-)] depletion and in the formation of hydrogen at the Pt CE.

Transiting extrasolar planetary candidates in the Galactic bulge.

More than 200 extrasolar planets have been discovered around relatively nearby stars, primarily through the Doppler line shifts owing to reflex motions of their host stars, and more recently through transits of some planets across the faces of the host stars. The detection of planets with the shortest known periods, 1.2-2.5 days, has mainly resulted from transit surveys which have generally targeted stars more massive than 0.75 M(o), where M(o) is the mass of the Sun. Here we report the results from a planetary transit search performed in a rich stellar field towards the Galactic bulge. We discovered 16 candidates with orbital periods between 0.4 and 4.2 days, five of which orbit stars of masses in the range 0.44-0.75 M(o). In two cases, radial-velocity measurements support the planetary nature of the companions. Five candidates have orbital periods below 1.0 day, constituting a new class of ultra-short-period planets, which occur only around stars of less than 0.88 M(o). This indicates that those orbiting very close to more-luminous stars might be evaporatively destroyed or that jovian planets around stars of lower mass might migrate to smaller radii.

Attributes of High-Performance Electron Transport Layers for Perovskite Solar Cells on Flexible PET versus on Glass.

Electron transport layers (ETLs) play a fundamental role in perovskite solar cells (PSCs) through charge extraction. Here, we developed flexible PSCs on 12 different kinds of ETLs based on SnO2. We show that ETLs need to be specifically developed for plastic substrates in order to attain 15% efficient flexible cells. Recipes developed for glass substrates do not typically transfer directly. Among all the ETLs, ZnO/SnO2 double layers delivered the highest average power conversion efficiency of 14.6% (best cell 14.8%), 39% higher than that of flexible cells of the same batch based on SnO2-only ETLs. However, the cells with a single ETL made of SnO2 nanoparticles were found to be more stable as well as more efficient and reproducible than SnO2 formed from a liquid precursor (SnO2-LP). We aimed at increasing the understanding of what makes a good ETL on polyethylene terephthalate (PET) substrates. More so than ensuring electron transport (as seen from on-current and series resistance analysis), delivering high shunt resistances (R SH) and lower recombination currents (I off) is key to obtain high efficiency. In fact, R SH of PSCs fabricated on glass was twice as large, and I off was 76% lower in relative terms, on average, than those on PET, indicating considerably better blocking behavior of ETLs on glass, which to a large extent explains the differences in average PCE (+29% in relative terms for glass vs PET) between these two types of devices. Importantly, we also found a clear trend for all ETLs and for different substrates between the wetting behavior of each surface and the final performance of the device, with efficiencies increasing with lower contact angles (ranging between ∼50 and 80°). Better wetting, with average contact angles being lower by 25% on glass versus PET, was conducive to delivering higher-quality layers and interfaces. This cognizance can help further optimize flexible devices and close the efficiency gap that still exists with their glass counterparts.

Simple and effective deposition method for solar cell perovskite films using a sheet of paper.

Most laboratories employ spin coating with application of antisolvent to achieve high efficiency in perovskite solar cells. However, this method wastes a lot of material and is not industrially usable. Conversely, large area coating techniques such as blade and slot-die require high precision engineering both for deposition of ink and for gas or for electromagnetic drying procedures that replace, out of necessity, anti-solvent engineering. Here we present a simple and effective method to deposit uniform high-quality perovskite films with a piece of paper as an applicator at low temperatures. We fabricated solar cells on flexible PET substrates manually with 11% power conversion efficiency. Deposition after soaking the sheet of paper in a green antisolvent improved the efficiency by 82% compared to when using dry paper as applicator. This new technique enables manual film deposition without any expensive equipment and has the potential to be fully automated for future optimization and exploitation.