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Shunt resistance R sh is a critical parameter for photovoltaic cells designed for low light indoor applications because it negatively affects the open circuit voltage, fill factor, and conversion efficiency. Standard CIGS cells are known to have low R sh and are, therefore, unpromising candidates for indoor energy sources. In this paper, we extend the original work of Virtuani et al. by determining the electrical specifications of many CIGS cells with copper contents [Cu]/([Ga]+[In]) as low as 0.33 and gallium contents between 0.28 and 0.81. First, IV data are fitted by a standard single-diode electrical circuit model for each illumination, resulting in light-dependent parameters. Then, we use a procedure based on a single dataset of electrical variables, i.e., independent of light, corrected by the experimental collection function, which captures light-dependent physical mechanisms. In this way, we are able to correctly reproduce the illuminance dependence of the electrical response of the PV cell over three orders of magnitude, in particular with a fixed value of the shunt resistance. The highest R sh is obtained with a low copper composition of 0.5 , regardless of the gallium composition. [ABSTRACT FROM AUTHOR]

Recently, global health has seen an increase in demand for assistance as a result of the COVID-19 pandemic. This has prompted many researchers to conduct different studies looking for variables that are associated with increased clinical risk, and find effective and safe treatments. Many of these studies have been limited by presenting small samples and a large data set. Using machine learning (ML) techniques we can detect parameters that help us to improve clinical diagnosis, since they are a system for the detection, prediction and treatment of complex data. ML techniques can be valuable for the study of COVID-19, especially because they can uncover complex patterns in large data sets. This retrospective study of 150 hospitalized adult COVID-19 patients, of which we established two groups, those who died were called Case group (n = 53) while the survivors were Control group (n = 98). For analysis, a supervised learning algorithm eXtreme Gradient Boosting (XGBoost) has been used due to its good response compared to other methods because it is highly efficient, flexible and portable. In this study, the response to different treatments has been evaluated and has made it possible to accurately predict which patients have higher mortality using artificial intelligence, obtaining better results compared to other ML methods. [ABSTRACT FROM AUTHOR]

We report Second Harmonic Generation (SHG) and Third Harmonic Generation (THG) energy conversion efficiencies up to 59% and 27%, respectively, for laser pulses simultaneously delivering high peak power in the sub-TW range and average powers in the sub-kW range. No damage or efficiency decrease is observed after more than 100 h operation time. The resulting high-energy visible and near-UV pulses are suitable for applications, such as lightning control, material analysis and machining, or OPCPA pumping. [ABSTRACT FROM AUTHOR]

Three alkali metal hydrogen phthalate salts (denoted as XAP, X = K+, Rb+, and Cs+) are chosen as substrates for the growth of quaterthiophene (4T) and hexathiophene (6T) thin films by organic molecular beam epitaxy to study the influence of gradual changes of surface unit cell parameters on the epitaxial growth. The increment of substrate lattice parameters increases the distance between the planes that define the furrows where oligothiophene molecules lie, while keeping unmodified the interactions between the overlayer and the substrate. Atom-atom potential simulations predict the preferential azimuthal orientations of the overlayer, which are compared with those experimentally observed. The agreement between simulations and experiments about contact planes and orientation of the crystalline domains in the films is satisfactory for both 4T/XAP and 6T/XAP. The increasing width of the surface furrows existing on moving from KAP to RbAP and CsAP does not cause any significant variation of the orientation and density of the overlayer domains, demonstrating that the interaction between overlayer and substrate is the key factor guiding organic epitaxial growth. [ABSTRACT FROM AUTHOR]

We report on the growth of 2D layered indium selenide films on (0001)-oriented sapphire substrates by coevaporation. The θ − 2θ x-ray diffractograms reveal that the (00l) planes are preferentially oriented parallel to the substrate with a tendency to deviate from the 2D stacking as a function of the growth time. The ϕ-scans performed for the (107) and (10 10) orientations of the hexagonal (h) and rhombohedral (r) phases, respectively, reveal that both polytypes coexist in the epitaxial films. We show that the merging of the h-(100), r-(101), h-(101), and r-(102) lines results in different spectral shapes in the θ − 2θ scans according to samples, which gives qualitative information about the contribution of each polytype. [ABSTRACT FROM AUTHOR]

The characterization of organic crystalline semiconductors in terms of possible phase transitions with temperature may be very important for the general knowledge of the material but also in view of application in devices: such properties may indeed cause variations in the macroscopic behavior of the material, especially relevant at the operation temperatures of few tens of degrees. Here, phase transitions in α-quaterthiophene single crystals are detected and studied by means of dielectric investigation, a powerful tool to go deeper in this matter. After describing the relative dielectric constant and the ac conductivity of the different solid phases, found to display either an insulating or a semiconducting character, quantitative information is provided on the relative stability of the different phases the active material may transform into, by giving an estimate of their entropy content. [ABSTRACT FROM AUTHOR]

A restricted angular random-walk model to build up polypeptide structures, which encompasses properties of the dihedral-angle Ramachandran map of folded proteins, is proposed to study the role of stochasticity on the compactness of the native state of proteins. Sample structures will be built with lengths ranging from 125 up to 400 amino acids for the different fractions of secondary structure motifs, from which dihedral angles were randomly chosen according to narrow Gaussian probability distributions. Physical properties of these polypeptide protein backbones such as the radius of gyration, the compactness parameter, the number of contacts, and the associated energy were computed and analyzed from an ensemble of thousands of realizations of protein peptide chains built with different rates of α-helix or β-strand motifs. Such geometric and physical parameters are compared to data from several globular proteins extracted from the Protein Data Bank indicating that a certain (small fraction) randomness is an essential ingredient for achieving the folded state of proteins, suggesting that they are neither driven by deterministic nor random-walk processes. [ABSTRACT FROM AUTHOR]

At 191 °C the organic semiconductor α-quaterthiophene is demonstrated to undergo a phase transition from the low temperature to the high temperature polymorph. Calorimetry, x-ray diffraction, optical reflectivity, and ellipsometry measurements were employed to analyze this transition and to show that this can be thermally induced on single crystals preserving the single crystalline nature of the sample over large domains. [ABSTRACT FROM AUTHOR]

Due to the large oscillator strength of the first molecular transition in oligothiophenes, a strong directional dispersion of the bu exciton transition is expected originating from the macroscopic polarization field. Examining such dispersion unambiguously usually requires different faces to be accessible for the optical measurements. Alternatively, measurements carried out at different angles of incidence are met with intrinsic limits due to the peculiarities of wave propagation in such anisotropic systems. In order to demonstrate these limits along with the experimental difficulties involved, we examine refraction and absorption of light in these crystals and discuss the effects of directional dispersion on the absorbance spectra of quaterthiophene crystals. © 2005 American Institute of Physics. [ABSTRACT FROM AUTHOR]

PbZrO[sub 3] (PZ) films of different thicknesses have been grown by metalorganic chemical vapor deposition on SrTiO[sub 3] (STO) substrates. The structure of the films was determined by x-ray diffraction and transmission electron microscopy. At the deposition temperature, the growth is cube on cube and is therefore heteroepitaxial. During cool down, PZ goes through a phase transformation from paraelectric to antiferroelectric at the Curie temperature and its cubic structure is stretched to orthorhombic. This results in domain formation in the PZ films corresponding to the different stretching directions. At room temperature, the thin PZ film consists of at least two different (120) domain variants and the thin-film-substrate relation can be described as (120)[002]PZ//(100) [00&1macr;-] STO for one of these variants. By etching down a thick film, it was observed that ∼260 nm is the threshold thickness, above which two additional different (002) domain variants appear in addition to the (120) domain variants. For one of the (002) domain variants, the thin-film-substrate relation can be described as (002)[100]PZ//(100)[011] STO. The surface morphology of the thick films, studied by scanning electron and atomic force microscopy, is partly covered with pyramids. These pyramids can originate from both (120) or (002) domains and are due to a higher growth rate of these two planes compared to the rest of the layer. A suggestion is made for pyramid-facet indexing for both domains. [ABSTRACT FROM AUTHOR]

Epitaxial PbZr[sub χ]Ti[sub 1-χ]O[sub 3] (PZT) films have been prepared by metalorganic chemical vapor deposition on SrTiO[sub 3] substrates. Two sets of films of thicknesses 50-100 and 700-1400 nm, containing 0%, 40%, 60%, and 100% Zr, were prepared and investigated. The refractive index n was determined by ellipsometry for the thin films and by reflectivity for the thicker films. Results were obtained over the energy range from 1.55 to 3.72 eV, and with a Cauchy-fit extrapolation down to 0.62 eV. The refractive-index curves show a systematic variation with composition. For all compositions, n is close to 3.2 at 3.72 eV (333 nm), while at 1.55 eV (800 nm) n is 2.35 for PZ (χ = 1) and 2.61 for PT (χ = 0). In agreement with previous results we find that the optical band gap is essentially independent of composition for PZT. We obtained 3.6 ± 0.1 eV. The n(E) results were analyzed by a Wemple-DiDomenico dispersion analysis, yielding results for the dispersion region in the ultraviolet. Unlike the band gap, which is insensitive to composition in PZT, the dispersion energy E[sub d] decreases from PT to PZ in the same fashion as the refractive index in the transparent region. [ABSTRACT FROM AUTHOR]

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The ability of the bis(imidazolyl)ketone ligand BMdiPhIK (bis(1-methyl-4,5-diphenylimidazolyl)ketone) to function as a redox active ligand has been investigated. The reduction of [M(BMdiPhIK)Cl2] (M = Fe and Zn) complexes resulted in a pinacol-type coupling to form dinuclear complexes featuring very weak and abnormally elongated C–C bonds (1.729(5) and 1.708(3) Å for Fe and Zn, respectively). Oxidation of these complexes using ferrocenium in the presence of Cl− ions regenerated the original [M(BMdiPhIK)Cl2] complexes, showing the reversibility of the coupling process. This makes it a potentially interesting approach for the storage of electrons and application of the BMdiPhIK ligand as a redox active ligand. [ABSTRACT FROM AUTHOR]

Dengue is a complex public health problem that is common in tropical and subtropical regions. This disease has risen substantially in the last three decades, and the physical symptoms depict the self-affine behavior of the occurrences of reported dengue cases in Bahia, Brazil. This study uses detrended fluctuation analysis (DFA) to verify the scale behavior in a time series of dengue cases and to evaluate the long-range correlations that are characterized by the power law exponent for different cities in Bahia, Brazil. The scaling exponent () presents different long-range correlations, i.e. uncorrelated, anti-persistent, persistent and diffusive behaviors. The long-range correlations highlight the complex behavior of the time series of this disease. The findings show that there are two distinct types of scale behavior. In the first behavior, the time series presents a persistent exponent for a one-month period. For large periods, the time series signal approaches subdiffusive behavior. The hypothesis of the long-range correlations in the time series of the occurrences of reported dengue cases was validated. The observed self-affinity is useful as a forecasting tool for future periods through extrapolation of the exponent behavior. This complex system has a higher predictability in a relatively short time (approximately one month), and it suggests a new tool in epidemiological control strategies. However, predictions for large periods using DFA are hidden by the subdiffusive behavior. [ABSTRACT FROM AUTHOR]

In this study, we have used RF-magnetron sputtering to deposit Al-doped ZnO (AZO) nanostructures thin films on poly-ethylene naphthalate (PEN) substrates. The compacted AZO nanopowders with different Al concentrations (0, 1, 2, 3 and 4 at.%), which were synthesized by sol-gel method combined with a supercritical drying process, have been used as targets. Structural, optical and electrical properties of deposited thin films with different Al concentrations have been investigated. X-ray diffraction results indicated that all the deposited thin films have hexagonal wurzite structure with c-axis orientation without any secondary phases. The SEM cross section image of the films revealed very dense columnar nanostructure. The best electrical properties (ρ = 4 × 10 Ω cm, µ = 22 cm V s, and n = 8 × 10 cm) were obtained for the AZO samples containing 2 at.% of Al. The thin films show an average transmittance of 80 % with the PEN substrate in the visible region. [ABSTRACT FROM AUTHOR]

The main studies on pitting consist in proposing Markovian stochastic models, based on the statistics of extreme values and focused on growing the depth of wells, especially the deepest one. We show that a non-Markovian model, described by a nonlinear Fokker-Planck (nFP) equation, properly depicts the time evolution of a distribution of depth values of pits that were experimentally obtained. The solution of this equation in a steady-state regime is a q-Gaussian distribution, i.e. a long-tail probability distribution that is the main characteristic of a nonextensive statistical mechanics. The proposed model, that is applied to data from four inspections conducted on a section of a line of regular water service in power water reactor (PWR) nuclear power plants, is in agreement with experimental results. [ABSTRACT FROM AUTHOR]

The authors report about accurate monitoring of ultralow La doses inserted in advanced high-k/ metal gate stacks for threshold voltage tuning purposes. Three characterization techniques are implemented for precise and reproducible lanthanum quantification. Low energy electron x-ray emission spectrometry capabilities are highlighted in terms of sensitivity and accuracy, thanks to a comparison with reference results obtained by Rutherford Backscattering Spectrometry. The capabilities of state-of-the-art Auger nanoprobes for depth profiling in the subnanometer range are also illustrated. [ABSTRACT FROM AUTHOR]

The study of a series of rubrene derivatives appropriately designed for limiting oxidation can be a powerful tool for clarifying the role of oxidation in the transport properties of crystalline rubrene, which is still unclear. Here, the synthesis of a series of substituted rubrene derivatives from dimerisation of propargyl alcohols is described together with the analysis of their stability to oxidation and electrochemical properties in solution. Millimetre-sized single crystals of all derivatives are grown and their structure determined from single crystal X-ray diffraction, which shows for all of them crystal packing features closely resembling those of orthorhombic rubrene. Finally, charge transport is studied by means of conductive AFM. The comparison between charge conduction in the crystalline state, oxidation potentials, and photo-oxidation kinetics allows ruling out rubrene endoperoxide as the origin of the high charge conductivity in both rubrene and rubrene derivatives, in agreement with an oxygen-enhanced conductivity model. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: This study assessed oxidative stress in LDL from obese patients with the metabolic syndrome and compared it with that in LDL from type 2 diabetic patients or control volunteers. It also determined the effect on platelets of LDL from the three groups. Methods: The profiles of lipids, fatty acids and fatty acid oxidation products were determined in LDL isolated from plasma of patients with the metabolic syndrome, patients with type 2 diabetes and volunteers ( n = 10 per group). The effects of LDL from the participant groups on the platelet arachidonic acid signalling cascade and aggregation were investigated. Results: Compared with LDL from control volunteers, LDL from obese metabolic syndrome and type 2 diabetic patients had lower cholesteryl ester, higher triacylglycerol and lower ethanolamine plasmalogen levels. Proportions of linoleic acid were decreased in phosphatidylcholine and cholesteryl esters in LDL from both patient groups. Among the markers of lipid peroxidation, oxidation products of linoleic acid (hydroxy-octadecadienoic acids) and malondialdehyde were increased by 59% and twofold, respectively in LDL from metabolic syndrome and type 2 diabetic patients. LDL from metabolic syndrome and type 2 diabetic patients were equally potent in activating the platelet arachidonic acid signalling cascade through increased phosphorylation of p38 mitogen-activated protein kinase and cytosolic phospholipase A, and through increased thromboxane B formation. LDL from patients with the metabolic syndrome and type 2 diabetes potentiated platelet aggregation by threefold and 3.5-fold respectively, whereas control LDL had no activating effects on platelets. Conclusions/interpretation: The metabolic syndrome in obese patients, without or with diabetes, is associated with increased oxidative stress in LDL, which triggers platelet activation. Trial registration:: ClinicalTrials.gov NCT00932087 Funding:: The study was funded by INSERM (Institut National de la Santé et de la Recherche Médicale) and ANR (Agence Nationale de la Recherche). [ABSTRACT FROM AUTHOR]

The article presents research which discussed facts, concepts and perspectives related to organic-organic heteroepitaxy. The researchers mentioned that such heteroepitaxy has the ability to represent the best techniques for growing oriented and crystalline heterostructures of organic semiconductors. They elaborate several paradigmatic examples of organic heteroepitaxy suggesting a possible physical rationale for the development of heterostructure interfaces.

The solid state magnetic properties of two new molecular organic materials based on polyfluoro- acridines functionalised with the 2,2,6,6-tetramethyl piperidine-1-oxyl radical (TEMPO) have been analyzed. After a first characterisation of the two materials by electron paramagnetic resonance and by X-ray diffraction, magnetisation measurements were performed from room temperature down to 2 K and the paramagnetic behaviour due to the unpaired spin on the radical TEMPO observed. Both compounds show some ferro-magnetic interactions down to 40 K, while at lower temperatures an antiferro-magnetic contribution switches on, possibly related to the reduction of intermolecular distances. [ABSTRACT FROM AUTHOR]

The major factor that drives a protein toward collapse and folding is the hydrophobic effect. At the folding process a hydrophobic core is shielded by the solvent-accessible surface area of the protein. We study the behavior of the numbers in 5526 protein structures present in the Brookhaven Protein Data Bank. The first digit of mass, volume, average radius and solvent-accessible surface area are measured independently and we observe that most of these geometric observables obey the Newcomb–Benford law. That is volume, mass and average radius obey the Newcomb–Benford law. Nevertheless, the digits of the solvent-accessible surface area do not agree with the Newcomb–Benford law. The present findings indicate that the hydrophobic effect is responsible for the anomalous first digit behavior of solvent-accessible surface areas. [ABSTRACT FROM AUTHOR]

We demonstrate that a driving ultrashort laser pulse undergoing filamentation can induce a remarkably large birefringence in Argon, resulting in an ultrafast “half-wave plate” for a copropagating non-filamenting probe beam. Such femtosecond birefringence, which originates from the difference between the nonlinear refractive indices induced by the filament on the axes parallel and orthogonal to its own polarization, opens the way to potential ultrafast Kerr-gates whose ultimate time-duration is only restricted by the duration of the driving pulse. We also show that the induced birefringence is transversely inhomogeneous, resulting from to the intensity profile of the driving pulse. [ABSTRACT FROM AUTHOR]

The transportation problems are in evidence due to their importance. This type of problem is usually studied by nonlinear dynamics. In this paper, we study time series of vehicle demand by using the ferry-boat system between Salvador city and Itaparica island, in Bahia, Brazil. We observe an interesting behavior since these time series allow to observe genuine self-affinity effects. The scaling exponent α and the density of crossing points ρ are variables to describe long-range correlations (self-affinity) in time series of the vehicle demand. As the result we show α and ρ variation year by year. [ABSTRACT FROM AUTHOR]

We study the behavior of the numbers in 412 light curves of cataclysmic variables, x-ray binary systems, galaxies, pulsars, supernovae remnants and other x-ray sources present in the public data collected by the instrument All Sky Monitor on board of the satellite Rossi x-ray timing explorer. The temporal light curves were analyzed applying Newcomb-Benford Law. The first digit of the x-ray light curves coming from astrophysical systems obeys the Newcomb-Benford Law as an intrinsic behavior. The nonextensive statistical mechanics behavior of astrophysical sources seem to be the cause for these sources to obey the Newcomb-Benford law. Some x-ray binary systems, however, do not follow this behavior. These systems obey either a gaussian or a bimodal distribution. [ABSTRACT FROM AUTHOR]

A Laponite clay-based lithium iodate nanocomposite has been synthesized for non-linear optical applications. The surface morphology of dip-coated optical waveguides were analysed by Scanning Force Microscopy (SFM) techniques. Individual Laponite particles were first imaged by using Intermittent-Contact Atomic Force Microscopy on pure Laponite layers. Electrostatic Force Microscopy was then used on nanocomposite waveguides in order to obtain a “chemical contrast” of sample surface. The strong electrical contrast observed was attributed to sample topography and not to the different properties of each nanocomposite constituent. Finally, in ambient conditions, dip-coated layers were also shown to be sensitive to humidity which leads to the occurrence of surface lithium iodate crystals with sub-micrometer size. [ABSTRACT FROM AUTHOR]

Within a new class of anthracene-like molecules, namely tetrafluoro-acridines, a systematic study of the structural and optical properties of single crystals of a prototypical member, 1,2,3,4-tetrafluoro-7(N,N)dimethyl-amino-acridine, is illustrated. Single crystals were grown by physical vapour transport using an inert gas flow as carrier, starting from a microcrystalline powder of the pure material. The crystal structure, determined by X ray diffraction, points out that the crystals are monoclinic with molecules stacked along the c axis. The results of atomic force microscopy on the ac face of a single crystal, at both low and molecular resolution, are consistent with the X-ray diffraction data. Preliminary results of the optical properties of the single crystal, in the unique configuration accessible due to the peculiar habit of the samples, are discussed. [ABSTRACT FROM AUTHOR]

In this paper the results of an experiment on soft X-ray contact microscopy using a laser-plasma source are presented. A resolution of 50 nm has been achieved imaging pig sperm cells, while other specimens, such as algae and yeast cells, showed internal details, proving the technique to be a powerful tool for biological investigations. Original biological information has been obtained and the conditions for optimal image formation have been studied. [ABSTRACT FROM AUTHOR]

Soft X-ray contact microscopy (SXCM), using a pulsed X-ray source, offers the possibility of imaging the ultrastructure of living biological systems at sub-100 nm resolution. We have developed a table-top pulsed plasma X-ray source for this application, generated by a large-volume XeCl laser, achieving a good conversion efficiency to 'water-window' X-rays (hν≈280-530 eV). Optimum plasma conditions for SXCM are discussed, including the effect of pulse duration, target material and resist development time on image resolution. Soft X-ray contact images of Chlamydomonas dysosmos (unicellular alga) and of the cyanobacterium Leptolyngbya are shown. [ABSTRACT FROM AUTHOR]