Revealing Long-Range Order in Brush-like Graft Copolymers Through In Situ Measurements of X-Ray Scattering During Deformation.

Brush-like graft copolymers (A-g-B), in which linear A-blocks are randomly grafted onto the backbone of a brush-like B-block, exhibit intense strain-stiffening and high mechanical strength on par with load-bearing biological tissues such as skin and blood vessels. To elucidate molecular mechanisms underlying this tissue-mimetic behavior, in situ synchrotron X-ray scattering was measured during uniaxial stretching of bottlebrush- and comb-like graft copolymers with varying densities of poly(dimethyl siloxane) and poly(isobutylene) side chains. In an undeformed state, these copolymers revealed a single interference peak corresponding to the average spacing between the domains of linear A-blocks arranged in a disordered, liquid-like configuration.

Effect of Secondary Paper Sludge on Physiological Traits of L. under Heavy-Metal Stress.

To eliminate the negative effect of soil contamination with heavy metals on plant growth and crop yield, different methods and techniques are the subject of discussion and study. In this study, we aimed to evaluate the effect of secondary pulp and paper-mill sludge application to soil on the response of the main physiological processes such as the growth, photosynthesis, and respiration of lettuce ( L.) plants to soil contamination with Pb.

Structure and Mechanical Response of Polybutylcarbosilane Dendrimers Confined in a Flat Slit: Effect of Molecular Architecture and Generation Number.

Due to the absence of specific interactions, carbosilane dendrimers are ideal models to study the effect of a hyperbranched regular structure on the molecular response to external influences. In this work, we have studied the conformational behavior of single polybutylcarbosilane dendrimers under confinement between impermeable flat surfaces using atomistic molecular dynamics simulations. Dendrimers of different generations belonging to two homologous series with a tetra-functional core and three- and four-functional branches were simulated.

Volcanic glass from the 1.8 ka Taupō eruption (New Zealand) detected in Antarctic ice at ~ 230 CE.

Chemical anomalies in polar ice core records are frequently linked to volcanism; however, without the presence of (crypto)tephra particles, links to specific eruptions remain speculative. Correlating tephras yields estimates of eruption timing and potential source volcano, offers refinement of ice core chronologies, and provides insights into volcanic impacts. Here, we report on sparse rhyolitic glass shards detected in the Roosevelt Island Climate Evolution (RICE) ice core (West Antarctica), attributed to the 1.

On electrochemistry of metal-organic framework Zn(EDTA)(HO).

Metal-organic compounds (MOFs) are a class of substances composed of metal ions or clusters coordinated to organic ligands to form one-, two-, or three-dimensional structures. Due to their high porosity, excellent adsorption and catalytic activity, as well as the possibility of simultaneous implementation of various charge accumulation mechanisms, they can be used as electrode materials for metal-ion batteries. However, a significant disadvantage is that most MOFs have a low electrical conductivity, and the production of conductive MOFs is a costly, time-consuming and technically difficult process.

Geochemical ice-core constraints on the timing and climatic impact of Aniakchak II (1628 BCE) and Thera (Minoan) volcanic eruptions.

Decades of research have focused on establishing the exact year and climatic impact of the Minoan eruption of Thera, Greece (c.1680 to 1500 BCE). Ice cores offer key evidence to resolve this controversy, but attempts have been hampered by a lack of multivolcanic event synchronization between records.

Community established best practice recommendations for tephra studies-from collection through analysis.

Tephra is a unique volcanic product with an unparalleled role in understanding past eruptions, long-term behavior of volcanoes, and the effects of volcanism on climate and the environment. Tephra deposits also provide spatially widespread, high-resolution time-stratigraphic markers across a range of sedimentary settings and thus are used in numerous disciplines (e.g.

Application of a conversion electrode based on decomposition derivatives of Ag[Fe(CN)] for aqueous electrolyte batteries.

The lack of stable electrode materials for water-based electrolytes due to the intercalation and conversion reaction mechanisms encourage scientists to design new or renovate existing materials with better cyclability, capacity, and cost-effectiveness. Ag[Fe(CN)] is a material belonging to the Prussian blue family that can be used, as its other family members, as an electrode material with the intercalation/deintercalation reaction or conversion-type mechanism through Ag oxidation/reduction. However, due to the instability of this material in its dry state, it decomposes to AgCN and a Prussian blue residual complex.

Ice core evidence for atmospheric oxygen decline since the Mid-Pleistocene transition.

The history of atmospheric oxygen (O) and the processes that act to regulate it remain enigmatic because of difficulties in quantitative reconstructions using indirect proxies. Here, we extend the ice-core record of O using 1.5-million-year-old (Ma) discontinuous ice samples drilled from Allan Hills Blue Ice Area, East Antarctica.

Hybrid Polycarbosilane-Siloxane Dendrimers: Synthesis and Properties.

A series of carbosilane dendrimers of the 4th, 6th, and 7th generations with a terminal trimethylsilylsiloxane layer was synthesized. Theoretical models of these dendrimers were developed, and equilibrium dendrimer conformations obtained via molecular dynamics simulations were in a good agreement with experimental small-angle X-ray scattering (SAXS) data demonstrating molecule monodispersity and an almost spherical shape. It was confirmed that the glass transition temperature is independent of the dendrimer generation, but is greatly affected by the chemical nature of the dendrimer terminal groups.

Adsorption of Silicon-Containing Dendrimers: Effects of Chemical Composition, Structure, and Generation Number.

We studied the conformational behavior of silicon-containing dendrimers during their adsorption onto a flat impenetrable surface by molecular dynamics (MD) simulations. Four homologous series of dendrimers from the 4th up to the 7th generations were modeled, namely, two types of carbosilane dendrimers differing by the functionality of the core Si atom and two types of siloxane dendrimers with different lengths of the spacers. Comparative analysis of the fractions of adsorbed atoms belonging to various structural layers within dendrimers as well as density profiles allowed us to elucidate not only some general trends but also the effects determined by dendrimer specificity.

The Impact of a Six-Year Climate Anomaly on the "Spanish Flu" Pandemic and WWI.

The H1N1 "Spanish influenza" pandemic of 1918-1919 caused the highest known number of deaths recorded for a single pandemic in human history. Several theories have been offered to explain the virulence and spread of the disease, but the environmental context remains underexamined. In this study, we present a new environmental record from a European, Alpine ice core, showing a significant climate anomaly that affected the continent from 1914 to 1919.

Effects of generation number, spacer length and temperature on the structure and intramolecular dynamics of siloxane dendrimer melts: molecular dynamics simulations.

The structure and properties of polysiloxane dendrimer melts are studied by extensive atomistic molecular dynamics simulations. Two homologous series differing in the spacer length are considered. In the first series the dendrimer spacers are the shortest ones, comprising only one oxygen atom, while in the second series the spacers consist of two oxygen atoms with the silicon atom in between.

Two-million-year-old snapshots of atmospheric gases from Antarctic ice.

Over the past eight hundred thousand years, glacial-interglacial cycles oscillated with a period of one hundred thousand years ('100k world'). Ice core and ocean sediment data have shown that atmospheric carbon dioxide, Antarctic temperature, deep ocean temperature, and global ice volume correlated strongly with each other in the 100k world. Between about 2.

Volcanic glass properties from 1459 C.E. volcanic event in South Pole ice core dismiss Kuwae caldera as a potential source.

A large volcanic sulfate increase observed in ice core records around 1450 C.E. has been attributed in previous studies to a volcanic eruption from the submarine Kuwae caldera in Vanuatu.

Sputtered Porous Li-Fe-P-O Film Cathodes Prepared by Radio Frequency Sputtering for Li-ion Microbatteries.

The increasing demands from micro-power applications call for the development of the electrode materials for Li-ion microbatteries using thin-film technology. Porous Olivine-type LiFePO (LFP) and NASICON-type LiFe(PO) have been successfully fabricated by radio frequency (RF) sputtering and post-annealing treatments of LFP thin films. The microstructures of the LFP films were characterized by X-ray diffraction and scanning electron microscopy.

A Comparative Study of Intramolecular Mobility of Single Siloxane and Carbosilane Dendrimers via Molecular Dynamics Simulations.

A comparative analysis of intramolecular dynamics of four types of isolated dendrimers from the fourth to the seventh generations belonging to the siloxane and carbosilane families, differing in spacer length, core functionality, and the type of chemical bonds, has been performed via atomic molecular dynamics simulations. The average radial and angular positions of all Si branching atoms of various topological layers within the dendrimer interior, as well as their variations, have been calculated, and the distributions of the relaxation times of their radial and angular motions have been found. It has been shown that the dendrons of all the dendrimers elongate from the center and decrease in a solid angle with an increasing generation number.

Electrodeposition of Polymer Electrolyte Into Porous LiNiMnO for High Performance All-Solid-State Microbatteries.

We report the electrodeposition of polymer electrolyte (PMMA-PEG) in porous lithium nickel manganese oxide (LiNiMnO) cathode layer by cyclic voltammetry. The cathode-electrolyte interface of the polymer-coated LNMO electrode has been characterized by scanning electron microscopy and electrochemical techniques. Electrochemical measurements consisting of galvanostatic cycling tests and electrochemical impedance spectroscopy revealed a significant improvement of the capacity values and the increase of the operating voltage.

The Role of Historical Context in Understanding Past Climate, Pollution and Health Data in Trans-disciplinary Studies: Reply to Comments on More et al., 2017.

Understanding the context from which evidence emerges is of paramount importance in reaching robust conclusions in scientific inquiries. This is as true of the present as it is of the past. In a trans-disciplinary study such as More et al.

Molecular dynamics simulations of single siloxane dendrimers: Molecular structure and intramolecular mobility of terminal groups.

Molecular dynamics simulations of two types of isolated siloxane dendrimers of various generations (from the 2nd to the 8th) have been performed for temperatures ranging from 150 K to 600 K. The first type of dendrimer molecules has short spacers consisting of a single oxygen atom. In the dendrimers of the second type, spacers are longer and comprised of two oxygen atoms separated by a single silicon atom.

A New Multielement Method for LA-ICP-MS Data Acquisition from Glacier Ice Cores.

To answer pressing new research questions about the rate and timing of abrupt climate transitions, a robust system for ultrahigh-resolution sampling of glacier ice is needed. Here, we present a multielement method of LA-ICP-MS analysis wherein an array of chemical elements is simultaneously measured from the same ablation area. Although multielement techniques are commonplace for high-concentration materials, prior to the development of this method, all LA-ICP-MS analyses of glacier ice involved a single element per ablation pass or spot.

New Zealand supereruption provides time marker for the Last Glacial Maximum in Antarctica.

Multiple, independent time markers are essential to correlate sediment and ice cores from the terrestrial, marine and glacial realms. These records constrain global paleoclimate reconstructions and inform future climate change scenarios. In the Northern Hemisphere, sub-visible layers of volcanic ash (cryptotephra) are valuable time markers due to their widespread dispersal and unique geochemical fingerprints.

Next-generation ice core technology reveals true minimum natural levels of lead (Pb) in the atmosphere: Insights from the Black Death.

Contrary to widespread assumptions, next-generation high (annual to multiannual) and ultra-high (subannual) resolution analyses of an Alpine glacier reveal that true historical minimum natural levels of lead in the atmosphere occurred only once in the last ~2000 years. During the Black Death pandemic, demographic and economic collapse interrupted metal production and atmospheric lead dropped to undetectable levels. This finding challenges current government and industry understanding of preindustrial lead pollution and its potential implications for human health of children and adults worldwide.

Electrochemical Deposition and Dissolution of Thallium from Sulfate Solutions.

The electrochemical behavior of thallium was studied on glassy carbon electrodes in sulfate solutions. Cyclic voltammetry was used to study the kinetics of the electrode processes and to determine the nature of the limiting step of the cathodic reduction of thallium ions. According to the dependence of current on stirring rate and scan rate, this process is diffusion limited.