Chemical Environment Research Articles

Robust Optical Physical Unclonable Function Based on Total Internal Reflection for Portable Authentication.

Physical unclonable functions (PUFs) utilize uncontrollable manufacturing randomness to yield cryptographic primitives. Currently, the fabrication of the most generally employed optical PUFs mainly depends on fluorescent, Raman, or plasmonic materials, which suffer inherent robustness issues. Herein, we construct an optical PUF with high environmental stability via total internal reflection (TIR-PUF) perturbed by randomly distributed polymer microspheres. The response image is transformed into encoded keys via an iterative binning procedure. The concentration of the polymer solution is optimized to debias the bit nonuniformity and maximize encoding capacity. The constructed TIR-PUF shows significantly high encoding capacity (2370) and markedly low total authentication error probability (1.614 × 10-23). The intra-Hamming distance is as low as 0.068, indicating the excellent readout reliability of TIR-PUF. The environmental stability of TIR-PUF has demonstrated promising results under a range of challenging conditions such as ultrasonic washing, high temperature, ultraviolet irradiation, and severe chemical environments. Moreover, the challenge-response pairs of our TIR-PUFs are demonstrated on an authentication system with low-power dissipation, lightweight components, and wireless imaging capture, rendering the possibility of portable authentication for practical applications.

Ion and Molecular Sieving with Ultrathin Polydopamine Nanomembranes.

In contrast to biological cell membranes, it is still a major challenge for synthetic membranes to efficiently separate ions and small molecules, due to their similar sizes in the sub-nanometer range. Inspired by biological ion channels with their unique channel wall chemistry that facilitates ion sieving by ion-channel interactions, we report here the first free-standing, ultrathin (10-17nm) nanomembranes composed entirely of polydopamine (PDA) as ion and molecular sieves. These nanomembranes are obtained via an easily scalable electropolymerization strategy and provide nanochannels with various amine and phenolic hydroxyl groups that offer a favorable chemical environment for ion-channel electrostatic and hydrogen bond interactions. They exhibit remarkable selectivity for monovalent ions over multivalent ions and larger species with K+/Mg2+ of ≈4.2, K+/[Fe(CN)6]3- of ≈10.3, and K+/Rhodamine B of ≈273.0 in a pressure-driven process, as well as cyclic reversible pH-responsive gating properties. Infrared spectra reveal hydrogen bond formation between hydrated multivalent ions and PDA, which prevents the transport of multivalent ions and facilitates high selectivity. We propose chemically rich, free-standing, and pH-responsive PDA nanomembranes with specific interaction sites as customizable high-performance sieves for a wide range of challenging separation requirements. This article is protected by copyright. All rights reserved.

Templated Synthesis of Copper Nanoclusters with a Hybrid Lysozyme-Polymer Material for Enhanced Fluorescence.

Hybrid materials that combine organic polymers and biomacromolecules offer unique opportunities for precisely controlling 3D chemical environments. Although biological or organic templates have been separately used to control the growth of inorganic nanoclusters, hybrid structures represent a relatively unexplored approach to tailoring nanocluster properties. Here, we demonstrate that a molecularly defined lysozyme-polymer resin material acts as a structural scaffold for the synthesis of copper nanoclusters (CuNCs) with well controlled size distributions. The resulting CuNCs have significantly enhanced fluorescence compared with syntheses based on polymeric or biological templates alone. The synergistic approach described here is appealing for the synthesis of biocompatible fluorescent labels with improved photostability.

LoCoHD: a metric for comparing local environments of proteins

Protein folds and the local environments they create can be compared using a variety of differently designed measures, such as the root mean squared deviation, the global distance test, the template modeling score or the local distance difference test. Although these measures have proven to be useful for a variety of tasks, each fails to fully incorporate the valuable chemical information inherent to atoms and residues, and considers these only partially and indirectly. Here, we develop the highly flexible local composition Hellinger distance (LoCoHD) metric, which is based on the chemical composition of local residue environments. Using LoCoHD, we analyze the chemical heterogeneity of amino acid environments and identify valines having the most conserved-, and arginines having the most variable chemical environments. We use LoCoHD to investigate structural ensembles, to evaluate critical assessment of structure prediction (CASP) competitors, to compare the results with the local distance difference test (lDDT) scoring system, and to evaluate a molecular dynamics simulation. We show that LoCoHD measurements provide unique information about protein structures that is distinct from, for example, those derived using the alignment-based RMSD metric, or the similarly distance matrix-based but alignment-free lDDT metric.

A new laboratory‐based method to experimentally induce diagenetic modifications in human bone tissue using archaeological gravesoils

AbstractThe conditions of the burial environment trigger microstructural modifications and physical‐chemical changes in the bone, such as chemical dissolution, increase of crystallinity, chemical exchanges, collagen degradation and changes in porosity, hence to reproduce these patterns is a challenging task. This work presents a new method to accelerate the diagenetic processes in the laboratory. Artificial aging is obtained by immersion at 80°C in “enriched” solutions derived from the leaching of gravesoils, maintaining the same pH, for 1 month, on modern bones collected from an autopsy. Two distinct solutions from two graves of the necropolis of Travo (IT) (7th–8th century AD) were adopted. The induced damage patterns, on the bone microstructure and the organo‐mineral fraction, have been compared with those observed on buried skeletal elements from the same graves, by providing a multi‐analytical approach (BSE‐SEM, EMPA, FT‐IR, MP‐AES). Bioapatite parameters, such as crystallinity index and Ca/P molar ratio, evolved similarly and, in some cases, reached the same values of buried bones. Conversely, in the absence of microbial activity, the organic fraction better survived the artificial aging. For the same reason, the porosity due to bioerosion was absent in the artificially aged samples, whereas the biological pores and the post‐mortem fractures exhibited the same histomorphology. It is believed that the opportunity of reproducing the diagenetic changes by replicating the chemical environment of the burial site at the laboratory scale is of great interest to forensic science and archaeology (e.g., to reconstruct the burial environment).

Oxygen Vacancy-Laden Confinement Impact on Degradation of Metal Complexes.

Oxygen vacancies (Vo) have been recognized as the superior active site for PS-mediated environmental remediation; however, the formation and activation of Vo associated with the effects of chemical and spatial environments remain ambiguous. Herein, attributing to the low defect-formation energy of Vo in the presence of sulfonate groups, an in situ nucleating Vo-laden CuO nanosheet was deliberately fabricated inside the phase of a sulfonated mesoporous polystyrene substrate (Vo-CuO@SPM). The as-prepared nanocomposite demonstrated an excellent treatment efficiency toward metal complexes [Cu-EDTA as a case] with ignorable Cu(II) leaching, and it can be repeatedly employed for 25 recycles (not limited). Mechanistically, the electron transfer and the mass transport for PDS nonradical activation were proved to be substantially enhanced by the delocalized electrons and with the assistance of the microchannel environment. This work not only establishes insight into the formation of oxygen vacancies but also reveals the PS activation mechanism in the spatially confined sites.

Hydrogel/MOF Dual-Modified Photoelectrochemical Biosensor for Antibiofouling and Biocompatible Dopamine Detection.

For accurate in vivo detection, nonspecific adsorption of biomacromolecules such as proteins and cells is a severe issue. The adsorption leads to electrode passivation, significantly compromising both the sensitivity and precision of sensing. Meanwhile, common antibiofouling modifications, such as polymer coatings, still grapple with issues related to biocompatibility, electrode passivation, and miniaturization. Herein, we propose a composite antibiofouling coating strategy based on zwitterionic metal-organic frameworks (Z-MOFs) and a combination of acrylamide hydrogels. On a well-designed TiO2/Z-MOF/hydrogel photoelectrode, we achieve highly sensitive and selective detection of dopamine in complex biological environments. The hydrogel's three-dimensional porous structure combined with unique microporous architecture of Z-MOF ensures effective sieving of interfering macromolecules while preserving efficient small molecules and electron transport. This innovative approach paves the way for constructing miniature, in vivo antibiofouling sensors for molecule monitoring in living organisms with complicated chemical environments.

Prediction of 3D RNA Structures from Sequence Using Energy Landscapes of RNA Dimers: Application to RNA Tetraloops.

Access to the three-dimensional structure of RNA enables an ability to gain a more profound understanding of its biological mechanisms, as well as the ability to design RNA-targeting drugs, which can take advantage of the unique chemical environment imposed by a folded RNA structure. Due to the dynamic and structurally complex properties of RNA, both experimental and traditional computational methods have difficulty in determining RNA's 3D structure. Herein, we introduce TAPERSS (Theoretical Analyses, Prediction, and Evaluation of RNA Structures from Sequence), a physics-based fragment assembly method for predicting 3D RNA structures from sequence. Using a fragment library created using discrete path sampling calculations of RNA dinucleoside monophosphates, TAPERSS can sample the physics-based energy landscapes of any RNA sequence with relatively low computational complexity. We have benchmarked TAPERSS on 21 RNA tetraloops, using a combinatorial algorithm as a proof-of-concept. We show that TAPERSS was successfully able to predict the apo-state structures of all 21 RNA hairpins, with 16 of those structures also having low predicted energies as well. We demonstrate that TAPERSS performs most accurately on GNRA-like tetraloops with mostly stacked loop-nucleotides, while having limited success with more dynamic UNCG and CUYG tetraloops, most likely due to the influence of the RNA force field used to create the fragment library. Moreover, we show that TAPERSS can successfully predict the majority of the experimental non-apo states, highlighting its potential in anticipating biologically significant yet unobserved states. This holds great promise for future applications in drug design and related studies. With discussed improvements and implementation of more efficient sampling algorithms, we believe TAPERSS may serve as a useful tool for a physics-based conformational sampling of large RNA structures.

Neural network kinetics for exploring diffusion multiplicity and chemical ordering in compositionally complex materials

Diffusion involving atom transport from one location to another governs many important processes and behaviors such as precipitation and phase nucleation. The inherent chemical complexity in compositionally complex materials poses challenges for modeling atomic diffusion and the resulting formation of chemically ordered structures. Here, we introduce a neural network kinetics (NNK) scheme that predicts and simulates diffusion-induced chemical and structural evolution in complex concentrated chemical environments. The framework is grounded on efficient on-lattice structure and chemistry representation combined with artificial neural networks, enabling precise prediction of all path-dependent migration barriers and individual atom jumps. To demonstrate the method, we study the temperature-dependent local chemical ordering in a refractory NbMoTa alloy and reveal a critical temperature at which the B2 order reaches a maximum. The atomic jump randomness map exhibits the highest diffusion heterogeneity (multiplicity) in the vicinity of this characteristic temperature, which is closely related to chemical ordering and B2 structure formation. The scalable NNK framework provides a promising new avenue to exploring diffusion-related properties in the vast compositional space within which extraordinary properties are hidden.

A novel Pd-doped perovskite-based LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst enhances NOx to ammonia reaction

The effect of Pd doping on the NOx removal efficiency and NH3 selectivity was studied over lean NOx trap LaCo1-xPdxO3-Ba/Al2O3-type catalysts. Two catalysts were prepared by the sequential impregnation of 15 wt% of LaCo1-xPdxO3-type perovskites and 20 wt% of barium over alumina. The results of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, temperature programmed techniques, UV–vis diffuse reflection absorption spectroscopy, and X-ray photoelectron spectroscopy demonstrated that perovskite and barium grains uniformly distribution over the alumina surface. Cobalt partial substitution by palladium changed the chemical coordination environment, thus leading to the redox properties of perovskites getting different. Moreover, the LaCoO3–Ba/Al2O3 catalyst exhibited a high reduction on NOx by H2 between 450 and 550 °C. Whereas Pd-doped LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst decreased the best activity interval around 100 °C, as well as improved the NH3 selectivity. The NOx reduction conversion of the LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst increased significantly from 72.9% to around 100% at H2/NO ratio = 1, and the production of NH3 was increased from 20.1% to 58.6% at H2/NO ratio = 3.

Precipitation of oxide dispersion strength steels after long-term annealing at temperature of 475 °C

Oxide dispersion strengthened steels are key alloys used in nuclear installations. Steels with chromium content of up to 10 wt % are suitable due to their advantageous properties and these alloys are used for the construction of technological devices in the primary circuit of nuclear power plants. From other studies, it can be concluded that chromium has anti-corrosive properties due to the formation of a passivation layer, which results in reduced activation of the material by thermal neutrons. Macroscopic properties are determined by their microstructure, and therefore, the description of the microstructure is important. Transmission Mössbauer spectroscopy and atom probe tomography were used to characterise the material. This provides information about the physical and/or chemical environment of the resonant atoms can be obtained. Obtained spectral parameters reach saturation values from which the solubility limit of chromium in iron can be determined. In Cr-rich phase, the solubility limit can be estimated from the value of spectral parameters of the single-line in the spectrum annealed for the longest time. The suggested procedures are subsequently applied to the case studies of stainless steels suitable for the construction of various components of the III+/IVth generation of nuclear reactors (including fast and fusion reactors).

Rational Design of Ultrafine Pt Nanoparticles with Strong Metal‐Support Interaction for Efficient Hydrogen Evolution

AbstractHydrogen evolution reaction (HER) plays an indispensable role in hydrogen economy. However, the development of highly active and durable Pt catalysts remains a great challenge. A homogenously‐dispersed, ultrafine and chemically anchored Pt‐based catalyst is successfully synthesized with the regulation of ‐SH groups tethered to SBA‐15 template. The ‐SH not only regulates the particle size of Pt, but also modifies the chemical environment of the carbon support by converting itself into heteroatom—S. The obtained catalyst (Pt/OMCSH) exhibits superior HER catalytic activity (15.4 mV at 10 mA cm−2; 28.4 mV dec−1; 1.0 M KOH) and stability to benchmark samples and most of the previously reported Pt‐based electrocatalysts. First‐principles calculations reveal that the presence of S in the carbon support regulates the electronic structure of Pt and strengthens the metal‐support interaction, thus boosting the reaction kinetics and enhancing the stability of Pt/OMCSH catalyst for HER.

Impact of defect concentration on piezoelectricity in Mn/Fe-doped KTN crystals

Defect engineering via doping exhibits considerable potential for improving the performance of environment-friendly lead-free piezoelectric materials. Owing to the susceptibility to lattice vibrations and the micro-local chemical environment, the readily available Mn/Fe transition metal elements (TMEs) facilitate the construction of defect structures. However, the role of TMEs in shaping the domain structures and the corresponding promotional mechanism of piezoelectricity need to be further decoded. Herein, we propose the different influence mechanisms of Mn and Fe ions on the ferroelectric domain and piezoelectric properties. Different concentrations of (MnNb/Ta′-VO••)• and (FeNb/Ta″-VO••)× defect dipoles are obtained based on the synergy of Mn/Fe ions with oxygen vacancies. Diverse ferroelectric behaviors resulting from (MnNb/Ta′-VO••)• and (FeNb/Ta″-VO••)× defect dipoles are observed. Furthermore, the variation of the dielectric diffusiveness with the defect dipole concentration is investigated. Trace concentration of (MnNb/Ta′-VO••)• generates strong diffusiveness. With the characterization of the ferroelectric domain, this strong diffusiveness is attributed to the lattice-like domain structure. Thereafter, the mechanisms of Mn/Fe defect dipoles on the formation of domain structures are clarified. Macroscopically, the dielectric and piezoelectric properties are measured with Mn/Fe ion components. Trace Mn doping and the resulting lattice-like domain significantly enhance the piezoelectric coefficient, resulting in an increase of nearly 50% for K(Ta,Nb)O3 single crystals. This work highlights the tremendous potential of TME-induced defect dipoles for modifying the ferroelectric domain and provides a reference paradigm for improving piezoelectricity through defect engineering.

Direct Work Function Measurement Using In-situ APXPS and Its Application on Copper Oxidation Process.

The work function (WF) measurement plays a critical role in engineering energy materials and energy devices. However, the ultra-high vacuum (UHV) environments of photoemission method limit the practical application for absolute work function measurements of materials, especially under complex working conditions. To understand the energy level of materials under complex chemical environments, the in-situ measurements of work function is necessary in complex metal/semiconductor system for various application. In this paper, we describe the utilization of ambient pressure X-ray photoemission spectroscopy (APXPS) with utilization of low photon energy X-ray for absolute WF measurements at BL02B of the Shanghai Synchrotron Radiation Facility. We herein present the WF measurement during oxygen adsorption on Pt(111) and oxidation of Cu(111) in ambient oxygen environment as demonstration of the APXPS capability for WF measurement. After oxygen chemisorption on Pt and formation of Cu2O, the WF will increase. This is due to charge transfer from metal to chemisorbed oxygen atoms. After the formation of bulk Cu2O and CuO, the WF value almost remain at ~5.5 eV. We believe the direct measurement of absolute work function via APXPS could help bridge the gap between the physical properties and the surface chemical species for metal/semiconductor materials.

Self-reconstructed ZIF-L/Co(OH)2 heterointerface modulates electronic structure of Ru and boosts electrocatalytic hydrogen evolution

Understanding the self-reconstruction behavior and activity modulation mechanism of MOFs in alkaline electrocatalysis is important for developing efficient Ru-based catalysts. As Co-based MOFs, leaf-shaped zeolitic imidazolate framework (ZIF-L) crystals can be partially self-reconstructed to Co(OH)2 by in situ alkaline electrochemical methods. In this regard, two models of ZIF@Ru/NF and Co(OH)2-ZIF@Ru/NF were fabricated, and calculated by DFT. The results showed that the Co(OH)2-ZIF heterointerface generated by self-reconstruction effectively modulated the chemical and electronic environment of Ru, leading to enhanced HER performance. Therefore, Co(OH)2-ZIF@Ru/NF was in situ grown on nickel foam (NF), using ZIF@Ru/NF as a precursor. After LSV activation, the leaf-shaped ZIF-L transformed into finely fragmented nanosheets of Co(OH)2. As anticipated, the Co(OH)2-ZIF@Ru/NF catalyst demonstrated superior electrocatalytic performance compared to numerous reported counterparts, exhibiting an overpotential of 22 mV at a current density of 10 mA cm−2 and a Tafel slope of 16.9 mV dec−1. This study presents a viable method for the preparation of HER electrocatalysts using electrochemical in situ self-reconstruction.

Fluorinated Surface Engineering towards High‐rate and Durable Potassium‐ion Battery

Solid electrolyte interphase (SEI) crucially affects the rate performance and cycling lifespan, yet to date more extensive research is still needed in potassium‐ion batteries. We report an ultra‐thin and KF‐enriched SEI triggered by tuned fluorinated surface design in electrode. Our results reveal that fluorination engineering alters the interfacial chemical environment to facilitate inherited electronic conductivity, enhance adsorption ability of potassium, induce localized surface polarization to guide electrolyte decomposition behavior for SEI formation, and especially, enrich the KF crystals in SEI by self‐sacrifice from C‐F bond cleavage. Hence, the regulated fluorinated electrode with generated ultra‐thin, uniform, and KF‐enriched SEI shows improved capacity of 439.3 mAh g‐1 (3.82 mAh cm­‐2), boosted rate performance (202.3 mAh g‐1 at 8.70 mA cm‐2) and durable cycling performance (even under high loading of ~8.7 mg cm‐2). We expect this practical engineering principle to open up new opportunities for upgrading the development of potassium‐ion batteries.

Fluorinated Surface Engineering towards High-rate and Durable Potassium-ion Battery.

Solid electrolyte interphase (SEI) crucially affects the rate performance and cycling lifespan, yet to date more extensive research is still needed in potassium-ion batteries. We report an ultra-thin and KF-enriched SEI triggered by tuned fluorinated surface design in electrode. Our results reveal that fluorination engineering alters the interfacial chemical environment to facilitate inherited electronic conductivity, enhance adsorption ability of potassium, induce localized surface polarization to guide electrolyte decomposition behavior for SEI formation, and especially, enrich the KF crystals in SEI by self-sacrifice from C-F bond cleavage. Hence, the regulated fluorinated electrode with generated ultra-thin, uniform, and KF-enriched SEI shows improved capacity of 439.3 mAh g-1 (3.82 mAh cm--2), boosted rate performance (202.3 mAh g-1 at 8.70 mA cm-2) and durable cycling performance (even under high loading of ~8.7 mg cm-2). We expect this practical engineering principle to open up new opportunities for upgrading the development of potassium-ion batteries.

Color morphing surfaces with effective chemical shielding

Color morphing refers to color change in response to an environmental stimulus. Photochromic materials allow color morphing in response to light, but almost all photochromic materials suffer from degradation when exposed to moist/humid environments or harsh chemical environments. One way of overcoming this challenge is by imparting chemical shielding to the color morphing materials via superomniphobicity. However, simultaneously imparting color morphing and superomniphobicity, both surface properties, requires a rational design. In this work, we systematically design color morphing surfaces with superomniphobicity through an appropriate combination of a photochromic dye, a low surface energy material, and a polymer in a suitable solvent (for one-pot synthesis), applied through spray coating (for the desired texture). We also investigate the influence of polymer polarity and material composition on color morphing kinetics and superomniphobicity. Our color morphing surfaces with effective chemical shielding can be designed with a wide variety of photochromic and thermochromic pigments and applied on a wide variety of substrates. We envision that such surfaces will have a wide range of applications including camouflage soldier fabrics/apparel for chem-bio warfare, color morphing soft robots, rewritable color patterns, optical data storage, and ophthalmic sun screening.

Effect of Novel pH Regulators on Copper film Chemical Mechanical Polishing for Ruthenium-Based Copper Interconnect under Weak Alkalinity Conditions

Abstract For Ruthenium (Ru)-based copper (Cu) interconnects Cu film chemical mechanical polishing (CMP), it is crucial to select appropriate pH regulators in the slurry to ensure the chemical reactions and maintain the stability of the polishing chemical environment. In this study, the effects of inorganic pH regulator KOH, organic pH regulator diethanolamine (DEA), and 2-amino-2-methyl-1-propanol (AMP) on CMP and slurry properties of Cu film were compared. It was found when using AMP as a pH regulator, the Cu/Ru removal rate selectivity (RRS) can reach 598:1, the surface roughness of Cu film decreased to 0.76 nm, and the slurry can remain stable for at least 7 days. The performance order of the three pH regulators is AMP＞KOH＞DEA. Meanwhile, through experimental results and test analysis, it has been confirmed that AMP can also play a multifunctional role as a complexing agent, dispersant, and surfactant. Therefore, AMP can replace KOH as a new pH regulator in weak alkaline slurries. This result plays an important role in guiding the selection of organic pH regulators in the optimization of Cu film CMP slurry.

High-throughput approach for investigating interdiffusion in medium- and high-entropy alloys

Interdiffusion experiments are usually time-consuming and tedious since diffusion couples must be annealed at several temperatures for a long time. The efforts required to study interdiffusion in multicomponent alloys increase dramatically as multiple diffusion couples are required to cover broad composition ranges and determine the diffusivities of individual elements in different chemical environments. To circumvent this challenge, we present a high-throughput approach applicable to single-phase and compositionally complex alloys, which are assumed to approximate ideal solid solutions. Here, a simple diffusion-multiple experiment combined with a physically based kinetic model is proposed to efficiently determine the diffusion coefficients of the constituent elements in quaternary CrFeCoNi alloys. Compared with tracer diffusivities reported in the literature, the results, thus, obtained do not differ by more than a factor of 2 and were obtained from a single interdiffusion experiment. In contrast, the diffusivities simulated with commercial mobility and thermodynamic databases are strongly overestimated by a factor ranging from 1 to 16. Therefore, our approach enables high-throughput determination of diffusivities and can help in the design of alloys for high-temperature applications where diffusion plays a key role.