Role of Central Atom on the Pressure Response of 2D Perovskites Containing a Long Alkyl Chain (Decylammonium, DA): DA2PbI4 and DA2GeI4

The application of an external pressure on Metal Halide Perovskite (MHPs) has become a fascinating way of tuning their optical properties, achieving also novel features. Here, the pressure response of 2D MHPs including a long alkyl chain made of ten carbon atoms, namely decylammonium (DA), has been investigated as a function of the central atom in DA2PbI4 and DA2GeI4. The two systems share a common trend in the phase stability, displaying a transition from an orthorhombic to a monoclinic phase around 2 GPa, followed by a phase separation in two monoclinic phases characterized by different c-axis. The optical properties show rather different behavior due to the presence of Pb or Ge. DA2PbI4 shows a progressive red shift of the band gap from 2.28 eV at ambient conditions, to 1.64 eV at 11.5 GPa, with a narrow PL emission composed by two components, with the second one appearing in concomitance with the phase separation and significantly shifted to lower energy. On the other hand, DA2GeI4, changes from a non-PL system at ambient pressure, to a clear broadband emitter centered around 730 nm (FWHM ~ 170 nm), with a large stoke shift, and an intensity maximum at about 3.7 GPa. This work sheds light on the structural stability of 2D perovskites characterized by extended alkyl chains, to date limited to four carbon atoms, and shows the pressure-induced emergence of broad emission in a novel lead-free perovskite, DA2GeI4. The evidence of wide emission by a moderate pressure in a germanium-based 2D MHP represents a novel result which may open the design, by chemical pressure, of efficient wide or even white lead-free emitters.

A combination of invasive and non-invasive techniques for the study of the palette and painting structure of a copy of Raphael's Transfiguration of Christ

The main objective of this study is to establish an appropriate method for the characterization of the pigments, materials and structure of the paint layers in a copy of the painting the Transfiguration of Christ by Raffaello Sanzio. A multi-technique approach that combines elemental, molecular and structural analyses and involves optical microscopy (OM), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM–EDX), μ-Attenuated Total Reflection–Fourier Transform InfraRed (µATR-FTIR), μ-Raman spectrometry (µRS) and non-invasive portable diffractometer (pXRD) was used. Our results revealed that this copy of the Transfiguration was executed with a palette, which includes white lead (cerussite and hydrocerussite), lazurite from lapis lazuli pigment, red and yellow earths (goethite, hematite and lepidocrocite), lead tin yellow, cinnabar, red lake, smalt and bone black, and fillers such as calcite, baryte (an impurity associated to some pigments), and traces of colorless powdered glass. A secondary objective of this research was the application of non-invasive in situ pXRD measurements, which do not require painting sampling and helped to confirm some inconclusive results obtained with other techniques regarding the artist's palette. The results showed the crystalline nature of all the pigments identified, which were known from ancient times and available during the 16th and 17th. Lastly, the used of 14C accelerator mass spectrometry determined that the canvas date was 1451–1633 AD (with a 95% confidence level). Although the main focus of the work was to improve the analytical methodology to better understand the artist’s palette, our results will further help us to explore the authorship of the copy or the school that executed it. Graphical Abstract

Analysis of pigments and damages for the 19th century White-robed Water-moon Avalokitesvara Painting in Gongju Magoksa Temple, Republic of Korea

The White-Robed Water-Moon Avalokiteshvara painting displayed on the rear wall of Daegwangbojeon (main hall) in Magoksa temple, is one of the representative Buddhist paintings in the late nineteenth century of Korea, and a valuable resource for understanding the coloring techniques and characteristics of Buddhist paintings in terms of expression and description in landscape painting. In this painting, the contours and colored surface remain undamaged, but blistering and exfoliation appear on some pigment layers. Furthermore, the partial decomposition of wooden materials due to wood-decay fungi and insect damage were found on the rear wall requiring proper treatment for long-term conservation. As the results of chromaticity and P-XRF analysis regarding the color pigment layer of the painting, the pigments were classified into ten types. The results suggest that the colors other than blue, green, yellow, red, black, and white were prepared by mixing two or more pigments. The types of pigments according to colors, were determined as traditional pigments with azurite; emerald green or clinoatacamite; 0 massicot; minium or hematite; Chinese ink; and kaolin, white lead, and gypsum, respectively. Violet and pink colors were assumed to have been prepared by mixing white with blue and red. In most of these pigments, small amounts of synthetic compositions from the modern era were detected at many points.

Effect of protein content on the thermal effusivity of foods

The availability of thermophysical properties of both foods and their constituents is of considerable importance to the industry. The thermal effusivity is one of the less explored thermophysical parameters. It governs the penetration of heat into materials and is defined as the square root of the product of thermal conductivity of the material, volume-specific heat capacity, and density. This paper describes the application of a relatively new inverse photopyroelectric method (IPPE) to determine thermal effusivity of dehydrated whey protein isolate and egg white powder versus protein content. In both cases the effusivity values decreased linearly with increasing protein content. One percent increase in protein content of whey protein isolate and egg white lead to 6.5 and 7.2 Ws1/2 m−2 K−1 decrease in effusivity values, respectively.

Analysis of Pigments and Damages for the 19th Century White-Robed Water-Moon Avalokitesvara Painting in Gongju Magoksa Temple, Korea

The White-Robed Water-Moon Avalokiteshvara painting displayed on the rear wall of Daegwangbojeon (main hall) in Magoksa temple, is one of the representative Buddhist paintings in the late 19th century of Korea, and a valuable resource for understanding the coloring techniques and characteristics of Buddhist paintings in terms of expression and description in landscape painting. In this painting, the contours and colored surface remain undamaged, but blistering and exfoliation appear on some pigment layers. Furthermore, the partial decomposition of wooden materials due to wood-decay fungi and insect damage were found on the rear wall requiring proper treatment for long-term conservation. As the results of chromaticity and P-XRF analysis regarding the color pigment layer of the painting, the pigments were classified into ten types. The results suggest that the colors other than blue, green, yellow, red, black, and white were prepared by mixing two or more pigments. The types of pigments according to colors, were determined as traditional pigments with azurite; emerald green or clinoatacamite; massicot; minium or hematite; Chinese ink; and kaolin, white lead, and gypsum, respectively. Violet and pink colors were assumed to have been prepared by mixing white with blue and red. In most of these pigments, small amounts of synthetic compositions from the modern era were detected at many points.

Revealing time’s secrets at the National Theatre of Costa Rica via innovative software for cultural heritage research

Establishing affordable, efficient, accessible, innovative, and multidisciplinary methodologies to the diagnosis of the conservation state of an artwork is key to carry out appropriate strategies of conservation and consequently to the creation of modern public policies on cultural heritage. Limited access to large-format paintings is a challenge to restoration scientists seeking to obtain information quickly, in a non-destructive and non-invasive manner, and identify regions of interest. Therefore, we put forward two unique software tools based on multispectral imaging techniques, with the long-term aim to assess the artist’s intentions, creative process, and colour palette. This development paves the way for a comprehensive and multidisciplinary understanding of the mysteries encompassed in each pictorial layer, through the study of their physical and chemical characteristics. We conducted the first ever study on Musas I and Musas II, two large-format paintings by Italian artist Carlo Ferrario, located in the National Theatre of Costa Rica. In this study, we used our novel imaging techniques to choose regions of interest in order to study sample layers; while also assessing the works’ state of conservation and possible biodeterioration. We explored the applications of our two versatile software tools, RegionOfInterest and CrystalDistribution, and confirmed paint stratigraphies by means of microscopy and spectroscopy analyses (OM, SEM-EDX, Fluorescent microscopy, FTIR-ATR and micro-Raman). In a pilot study, we identified the artist’s main colour palette: zinc white, lead white, chrome yellow, lead read, viridian, along with artificial vermilion and ultramarine pigments. We were able to identify artificial vermilion and ultramarine and distinguish them from the natural pigments using CrystalDistribution to map the average size and diameter of the pigment crystals within the paint layers. This study demonstrated that software-based multidisciplinary imaging techniques are novel in establishing preventive and non-invasive methods for historical painting conservation studies, in addition, this study provides tools with great potential to be used in the future in applications such as virtual restoration.

Beyond Behavior: Prevalences, Penalties, and Ethno-racial Inequalities in Poverty

Ethno-racial differences in poverty are substantial and persistent in the US. To explain these differences, scholars have relied largely on behavioral explanations, which argue that poverty is the result of high prevalences of problematic behaviors or “risks.” Given substantial differences in the prevalence of risks, scholars intuit that ethno-racial differences in poverty are explained by disproportionately high prevalences of risks in Black and Latino populations. However, these approaches rely heavily on untested assumptions regarding the relationship between risks and poverty rates. Using the 1993-2016 Current Population Survey and the Urban Institute’s TRIM3 model to derive high-quality estimates of income and poverty, I confirm persistent and substantial ethno-racial differences in poverty. Next, I employ a prevalences and penalties framework to compare risks in Black, Latino, and white-lead households. This framework is then leveraged to estimate counterfactual models to predict Black and Latino poverty rates given alternative prevalences of risks. The findings demonstrate that if the prevalence of risks for Black and Latino Americans was equal that of whites, poverty rates would remain over twice as high for Black and Latino individuals compared to whites. Furthermore, even when risks are eliminated for Black and Latino Americans, poverty remains substantially higher compared to whites. These findings undermine behavioral approaches to understanding poverty and point to the need for scholars to pursue alternatives, including structural and political explanations.

Effects of processing on amino acids composition of Leucaena leucocephala (Lam De Wit) leaf meal

The high cost of animal protein sources has made it necessary to evaluate the use of alternative plant protein sources especially unconventional plant proteins. Leucaena leucocephala (white lead tree) is a leguminous plant, the leaves of which have the potential of being used as a plant protein source. Leucaena leaf has been analysed to have a crude protein value of 15.2-34.3%. The plant leaves were collected from the forage section of the College of Agriculture and Animal Sciences (CAAS) Mando, Kaduna. The first group of the leaves was divided into three and sun-dried for 24 hours, 48 hours and 72 hours respectively. The second group was further divided into three subgroups which were soaked in water for 24 hours, 48 hours and 72 hours then sun-dried. The two groups of the leaves were ground into leaf powder. The effects of sun-drying and soaking on amino acid composition of L. leucocephala leaves was investigated. The amino acid analysis was done by ion-exchange chromatography (IEC) using the Technicon Sequential Multisample Amino Acid Analyser (TSM) Technicon Instruments Corporation, New York. The essential amino acids detected in L. leucocephala leaf were arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine and valine. Alanine, cysteine, tyrosine, aspartic acid, glutamic acid, glycine, serine and proline were the non-essential amino acids detected. Sun-drying and soaking led to significant (P≤0.05) losses in the concentration of all the amino acids in the leaf samples (Sundried for 24 hours - SD1, Sundried for 48 hours - SD2, Sundried for 72 hours - SD3, soaked in water for 24 hours – SW1, soaked in water for 48 hours - SW2, soaked in water for 72 hours - SW3) when compared with the raw leaf samples (SU). Soaking caused higher reduction in the amino acid levels when compared to sun-drying in the test leaf meals which was significant at P≤0.05. The amino acid scores revealed that lysine and methionine were the limiting amino acids in L. leucocephala leaves relative to WHO/FAO/UNU standard for preschool aged children. Therefore, processed L. leucocephala leaves should be supplemented with other feed ingredients rich in these amino acids for animal feed production. Keywords: Leucaena leucocephala leaf, sun-drying, soaking, amino acid composition.

Analytical study and structural treatment for a thin panel painting

Purpose This paper aims to provide a deeper understanding of the painting techniques, materials used and deterioration phenomena in a thin panel painting. As well as, straightening buckling in a thin panel painting and reinforcement have been used by an auxiliary support system. Design/methodology/approach This requires using several scientific and analytical techniques to provide a deeper understanding of the painting techniques, materials used, deterioration phenomena and a greater awareness of how well treatment the panel painting is. Visual observation and multispectral imaging (Visible Ultraviolet-induced luminescence, as well as Ultraviolet reflected and Infrared [IR]), optical Microscopy (OM), handheld X-ray fluorescence spectroscopy (XRF), X-ray diffraction, Fourier transform IR spectroscopy (FTIR) and gas chromatography were used in this case study. Findings The analytical study of a thin panel with different methods allowed defining that the thin panel painting consists of plywood panel, ground layer (white lead and animal glue) and painted layer (lead red, cobaltic black, chrome yellow, Venetian red, iron black and white lead and poppy oil). Also, these determined that a convex buckling was the main form of deterioration. The structure treatment was executed by using a wet compress to straighten the thin panel painting and followed by fixing a new special design of the second auxiliary support system on the back of the thin panel painting. Originality/value The importance of analytical study to determine the painting techniques, materials used, deterioration phenomena and how well treatment the panel painting is. As well as, using a wet compress to straightening of warping or buckling wooden panel painting. Also, the Plexiglas second auxiliary support system could use to reinforcement the wooden panel and control the wooden panel movements.