Amorphous Crystallization Research Articles

Ultra-Fast and In-Depth Reconstruction of Transition Metal Fluorides in Electrocatalytic Hydrogen Evolution Processes.

Hitherto, there are almost no reports on the complete reconstruction in hydrogen evolution reaction (HER). Herein, the authors develop a new type of reconfigurable fluoride (such as CoF2) pre‐catalysts, with ultra‐fast and in‐depth self‐reconstruction, substantially promoting HER activity. By experiments and density functional theory (DFT) calculations, the unique surface structure of fluorides, alkaline electrolyte and bias voltage are identified as key factors for complete reconstruction during HER. The enrichment of F atoms on surface of fluorides provides the feasibility of spontaneous and continuous reconstruction. The alkaline electrolyte triggers rapid F− leaching and supplies an immediate complement of OH− to form amorphous α‐Co(OH)2 which rapidly transforms into β‐Co(OH)2. The bias voltage promotes amorphous crystallization and accelerates the reconstruction process. These endow the generation of mono‐component and crystalline β‐Co(OH)2 with a loose and defective structure, leading to an ultra‐low overpotential of 54 mV at 10 mA cm−2 and super long‐term stability exceeding that of Pt/C. Moreover, DFT calculations confirm that F− leaching optimizes hydrogen and water adsorption energies, boosting HER kinetics. Impressively, the self‐reconstruction is also applicable to other non‐noble transition metal fluorides. The work builds the fundamental comprehension of complete self‐reconstruction during HER and provides a new perspective to conceive advanced catalysts.

Effects of phosphorus substitution on amorphous formation, crystallization behavior and magnetic properties of FeSiBCuNb alloys

Fe-Si-B-Cu-Nb nanocrystalline alloys exhibit excellent soft magnetic properties and have been increasingly applied in high frequencies ranging from several kHz to several hundred kHz, but the magnetic permeability needs further to design to meet the magnetic components under different frequencies. In the present work, the influences of phosphorus substitution on amorphous forming, crystallization behavior and soft magnetic properties of silicon-rich Fe-Si-B-Cu-Nb alloys were systematically investigated. It was found that the suitable addition of 1 at.% of P in Fe-Si-B-Cu-Nb alloy can significantly improve the amorphous forming ability, reduce the coercivity (Hc) of the annealed alloys and elevate the effective magnetic permeability (μe) at frequencies ranging from 1 to 30 kHz in spite of having fractional detriment to the alloy's thermal stability but still remaining a relatively broad annealing temperature region. Besides, the μe in high P-containing alloys becomes insensitive to frequencies at high frequencies region, which can attain frequencies-dependent constant magnetic permeability induced by composition design.

Protocols to Dissolve Amorphous Urate Crystals in Urine.

Amorphous urate crystals can obscure significant findings during a routine urinalysis. There is no standardized protocol to minimize their effect. We tested 210 urine specimens. Three specimens had high red blood cell (RBC) or white blood cell (WBC) counts. Fifty-six specimens formed amorphous urates. Sediment from these specimens was treated with 50 mM sodium hydroxide (NaOH) at a 1:2 and/or 1:4 dilution. We warmed 22 specimens with crystals at various temperatures. Amorphous urate crystals formed in concentrated urine with an acidic pH. Adding 50 mM NaOH dissolved amorphous urates, revealing the presence of underlying bacteria and yeast, but WBC and RBC counts were grossly decreased. Prewarming unspun specimens to 60°C for 90 seconds dissolved most amorphous urates. The protocol to eliminate amorphous urate crystals is to prewarm the specimen before testing. Adding 50 mM NaOH to sediment dissolves amorphous urates to enhance the visibility of bacteria and yeast but has a deleterious effect on WBC and RBC.

Evaluation of hematological and urine parameters of Anoa (Bubalus Spp.) at Environment and Forestry Research and Development Institute of Manado (BP2LHK)

Anoa (Bubalus spp.) is an endemic species found only on Sulawesi Island, Indonesia. The lack of intact review evaluating the physiological condition leads to difficulties in the conservation efforts of this endangered species. This study aimed to examine the hematological and urine parameters of Anoa at the Environment and Forestry Research and Development Institute of Manado (BP2LHK). Four Anoa were used in this study. The physiological conditions were recorded during the study period, while hematological and urine parameters were only examined once and twice, respectively, due to limited access to the animals. The level of hemoglobin was 17.18 ± 0.8 g/dL, packed cell volume of 45.22 ± 3.4 %, total erythrocyte count was 10.46 ± 0.5 ×106/µl and total leukocyte count was 5.65 ± 1.0 ×103/µl. The mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration was 43.38 ± 3.5 fl, 16.48 ± 0.7 gl, and 38.28 ± 1.3 g/dL, respectively. The urine leukocytes were 0-15 leuko/µl, urobilinogen level was 3.50 µmol/L, protein value was 39.50 ± 10.3 mg/dL, and urine pH and urine density were 9.00 and 1.00 g/mL, respectively. The urine sedimentation analysis showed the formation of the urinary crystal (amorphous crystal, calcium carbonate, and struvite). We conclude that hematological and urine parameters were not different among Anoa in this study.

Effect of External Impacts on the Structure and Martensitic Transformation of Rapidly Quenched TiNiCu Alloys

TiNi-TiCu quasibinary system alloys with a high Cu content produced by rapid quenching from liquid state in the form of thin amorphous ribbons exhibit pronounced shape memory effect after crystallization and are promising materials for miniaturized and fast operating devices. There is currently no complete clarity of the mechanisms of structure formation during crystallization from the amorphous state that determine the structure-sensitive properties of these alloys. This work deals with the effect of the initial amorphous state structure and crystallization method of the alloys on their structure and phase transformations. To this end the alloy containing 30 at.% Cu was subjected to thermal and mechanical impact in the amorphous state and crystallized using isothermal or electropulse treatment. We show that after all types of treatment in the amorphous state the structure of the alloy remains almost completely amorphous but the characteristic temperatures and enthalpy of crystallization become slightly lower. Isothermal crystallization of alloy specimens produces a submicrocrystalline structure with an average grain size in the 0.4–1.0 μm range whereas electropulse crystallization generates a bimorphic structure consisting of large 4–6 μm grains and 2–3 μm high columnar crystals in the vicinity of the surface. The grains have nanosized plate-like and subgrain structures. The largest grains are observed in thermally activated samples, meanwhile, mechanical impact in the amorphous state leads to the formation of equiaxed finer grains with a less defective subgrain structure and to the shift of the temperature range of the martensitic transformation toward lower temperatures.

Investigation on cogasification and melting behavior of ash-rich biomass solid waste and Ca-rich petrochemical sludge pyrolysis residue in CO2 atmosphere

The process of gasification coupled with melting is an effective technology that can realize the clean disposal of hazardous solid wastes. In this study, the gasification and melting characteristics of Chinese medicine residue (CMR) and pyrolysis residue of petrochemical sludge (PRPS) blends were investigated. The gasification residues obtained at different gasification temperatures and with variant blend ratios (mass ratio of CMR to PRPS) were evaluated. Results demonstrated that the melting degree of gasification residues was proportional to gasification temperature, presenting as four distinct morphologies: the CaO-rich powder-like (1100 °C), the gehlenite-rich black-gray hemispherical (1200 °C), virid amorphous crystal (1300 °C), and transparent vitrified SiO2 (1400 °C). Especially, as increasing the content of CMR, the gasification and melting characteristic was promoted, which were related to energy resource attributes of CMR and supply of low-melting eutectic constituent elements. In addition, when the gasification temperature was 1300 °C, the mineral composition of gasification residues gradually transformed from Ca–Si–Al compounds into amorphous matter as increasing CMR content. Moreover, while the blend ratio further attained to 3:1, gasification residues appeared as distributed globules and syngas productivity was enhanced to 0.99 L/g. The leachability of heavy metals inside the melting slags could meet the established criteria, indicating the harmless disposal of hazardous wastes.

Oxidation and cracking behaviors of triple-layered Cr2AlC coating

Cr 2 AlC coating has potential applications as high temperature protective coating . However, inevitable interdiffusion at coating/substrate interface promotes Al depletion and deteriorates its oxidation resistance . In the present work, the oxidation behavior of a triple-layered Cr 2 AlC coating, with (Cr,Al) 2 O 3 inner layer, amorphous intermediate layer and crystalline Cr 2 AlC outer layer, was investigated at 900 and 1000 °C in air. The effect of the (Cr,Al) 2 O 3 inner layer as diffusion barrier was evaluated during the oxidation process . It is showed that the triple-layered Cr 2 AlC coating could effectively improve the oxidation resistance of the M38G alloy substrate, due to the Cr 2 AlC outer layer. The (Cr,Al) 2 O 3 inner layer could prohibit internal nitridation and retard interdiffusion at the coating/substrate interface, improving oxidation resistance of the triple-layered Cr 2 AlC coating. Furthermore, cracking of the triple-layered Cr 2 AlC coating was found after oxidation at 900 and 1000 °C, due to the thermal stress and internal stress introduced by intermediate amorphous layer crystallization during oxidation. • The triple-layered coating improves the oxidation resistance of the M38G alloy effectively. • The (Cr,Al) 2 O 3 inner layer prohibits inter diffusion and internal nitridation during oxidation. • Thermal stress and stress due to amorphous layer crystallization lead to cracking of the coating.

Characteristics and Environmental Response of White Secondary Mineral Precipitate in the Acid Mine Drainage From Jinduicheng Mine, Shaanxi, China

The study focuses on the white secondary mineral precipitate and its environmental response formed in acid mine drainage (AMD) at Jinduicheng Mine (Shaanxi, China). The mineral composition of white precipitate was characterized by Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), X-ray photoelectron spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Inductively coupled plasma-atomic emission spectrometer (ICP-AES), chemical quantitative calculation and PHREEQC software. The white precipitate was a kind of amorphous crystal with the characteristics of a fine powder, and its main elements were O, Al, S, F, OH- and SO42- groups. Moreover, by comparing the mole number of chemical elements, the main mineral composition of the white precipitate was closest to basaluminite. The geochemical simulation result of the PHREEQC software verified that the white precipitate was basaluminite. According to the analysis of water quality characteristics of water samples, basaluminite can reduce the ions content in the AMD and enrich Cu, Ni, Mo, Cr and F ions, showing an excellent self-purification capacity of the water body. These results are helpful to improve the understanding of secondary mineral and its environmental response, and are of great significance for the environmental protection and sustainable development of mining area.

Highly Emissive Biological Bilirubin Molecules: Shedding New Light on the Phototherapy Scheme.

Bilirubin (BR) is the main end-product of the hemoglobin catabolism. For decades, its photophysics has been mainly discussed in terms of ultrafast deactivation of the excited state in solution, where, indeed, BR shows a very low green emission quantum yield (EQY), 0.03%, resulting from an efficient nonradiative isomerization process. Herein, we present, for the first time, unique and exceptional photophysical properties of solid-state BR, which amend by changing the type of crystal, from a closely packed α crystal to an amorphous loosely packed β crystal. BR α crystals show a very bright red emission with an EQY of ca. 24%, whereas β crystals present, in addition, a low green EQY of ca. 0.5%. By combining density functional theory (DFT) calculations and time-resolved emission spectroscopy, we trace back this dual emission to the presence of two types of BR molecules in the crystal: a “stiff” monomer, M1, distorted by particularly strong internal H-bonds and a “floppy” monomer, M2, having a structure close to that of BR in solution. We assign the red strong emission of BR crystals to M1 present in both the α and β crystals, while the low green emission, only present in the amorphous (β) crystal, is interpreted as M2 emission. Efficient energy-transfer processes from M2 to M1 in the closely packed α crystal are invoked to explain the absence of the green component in its emission spectrum. Interestingly, these unique photophysical properties of BR remain in polar solvents such as water. Based on these unprecedented findings, we propose a new model for the phototherapy scheme of BR inside the human body and highlight the usefulness of BR as a strong biological fluorescent probe.

Morphological characterization using scanning electron microscopy of fly artifacts deposited by Calliphora vomitoria (Diptera: Calliphoridae) on household materials

Insects found at a crime scene can produce traces referred to as fly artifacts (FA) due to their movement over the corpse and the manner in which they feed upon it. These can be detrimental for carrying out criminal investigations. Confusing a FA with a genuine bloodspot can lead to misinterpretations, also taking into consideration that FA may contain a human DNA profile. The aim of the present study was to employ scanning electron microscopy (SEM) for the analysis of FA produced by Calliphora vomitoria on hard surfaces and fabrics that are commonly present at crime scenes. FA and control bloodstains were produced under experimental conditions on metal, glass, plaster, cotton, and polyester. After macroscopic analysis, FA were examined at standard low (20–40 ×), medium low (300–600 ×), and high ultrastructural (1200 ×) magnification through a SEM Stereoscan 360, Leica, Cambridge. SEM analysis enabled the identification of distinctive features of FA on hard surfaces, namely, amorphous crystals, micro-crystals with a morphology similar to those of uric or micro-crystals with a comparable morphology to cholesterol, absent in controls. Moreover, red blood cells (RBC) were absent in FA but were always present in controls. On cotton, for both FA and controls, the drop was almost completely absorbed and thus indistinguishable from the underlying fabric texture. On polyester, FA showed amorphous/crystal-like deposits and no RBC, as observed on hard surfaces, except for those showing a completely flat surface. SEM analysis appeared to be suitable for differential diagnosis between FA and genuine bloodstains on hard surfaces, although the results may be inconclusive on tested fabrics.

A novel approach to prepare high strength and high porosity reticulated porous ceramics by in-situ synthesis of mullite whiskers

A novel fabrication method for reticulated porous ceramics (RPCs) with high strength and high porosity has been proposed based on polymeric replica method and in-situ synthesis of mullite whiskers. Through the FactSage theoretical prediction, the mullite was produced in A10, A15 and A20 coating slurries and the liquid phase viscosity was decreased with increasing sintering temperature and AlF3 content. The results show that as the AlF3 content in coating slurry increases, the amount of mullite phase increases and the internal pore structure of the struts in the RPCs changed from triangular to rounded. Adding appropriate AlF3 content in the coating slurry facilitated the growth of mullite whiskers, but excessive AlF3 content caused the formation of amorphous crystals. The method used here improved the compressive strength without significantly reducing the porosity. Compared to untreated specimens, the compressive strength and residual strength ratio of sample A15 were increased by 38.24% and 19.75%.

Photonic Plasticines with Uniform Structural Colors, High Processability, and Self-Healing Properties.

Despite the vast variety of colloidal superstructures available in soft matter photonics, it remains challenging to balance the trade-off between their optical microstructures and material processability. By synergizing colloidal photonics and dynamic chemistry, a type of photonic "plasticine" with characteristics of uniform structural colors, high processability, and self-healing is demonstrated. Specifically, a boronate ester bond-based macromonomer is first prepared through complexation between the diols of polyvinyl alcohol and the boronic acid group of 3-(acrylamido) phenylboronic acid in the presence of concentrated silica colloids. Upon photopolymerization, the dynamic photonic plasticine is formed in situ as the result of the crosslinking of the boronate ester bonded networks. The randomly packed colloids inside the plasticine compose the amorphous photonic crystals, giving rise to angle-independent structural colors that would not compromise during subsequent processing steps; the reversible nature of the boronate ester bonds endows the plasticine with self-adaptable and self-healing properties. Further, the plasticine is also compatible with common shaping methods, that is, cutting, molding, and carving, and thus can be facilely processed into 3D structural colored objects, holding great potentials in fields such as bio-encoding, optical filters, anti-counterfeiting, etc.

More reasons to add less salt – NaCl's unfavourable impact on glass transition and moisture sorption of amorphous maltose-NaCl blends

Adding NaCl to maltose depressed the glass transition temperature (T g ) of freeze-dried maltose-(dissociated) NaCl powder (by up to 9.1 °C at 10%mol addition level) but did not impact sorption isotherm in the water activity (a w ) range of 0.1–0.3. Above 2%mol NaCl, moisture and NaCl had an antagonistic effect on T g depression of freeze-dried maltose-NaCl powder. According to linear and Flory-Fox models, T g increased linearly with mixtures’ molecular weight. T g and sorption isotherm curves were then combined to determine the a w at which glass transition occurs at various storage temperatures (i.e. critical a w ). From the combined curve, critical a w decreased linearly with increased NaCl concentration in the mixture. Furthermore, the critical a w depression was steeper at higher temperatures. Finally, neither processing (dry mixing versus freeze drying) nor NaCl concentration affected the crystallization kinetics of amorphous maltose during dynamic humidification (0 to over 90% relative humidity) at 25 °C. • NaCl lowered the temperature and humidity at which amorphous maltose becomes sticky. • Temperature sensitivity can be predicted by amorphous mixtures' molecular weight. • Adding ≤10%mol NaCl did not affect amorphous maltose's crystallization kinetics.

Self-assembly of colloidal particles into amorphous photonic crystals

This review focuses on the introduction, fabrication, and applications of amorphous photonic crystals.

Relationship between crystal shape and unit cell shape: crystal shape modification via co-crystallization toward SXRD-suitable crystals

The relationships between the shape and cell parameters were investigated using 131 crystals of secondary aromatic sulfonamides. And, 11 sulfonamides isolated as oils, amorphous, or needle crystals were co-crystallized to obtain block-like crystals.

Alkaloid compound from Tombili (Caesalpinia bonduc) as biopesticide agent on rice plants

The purpose of these study is to determine the effect of active compound from tombili seed extract as a vegetable pesticide in the prevention of soil pest in rice plants. The method of these researches is isolation to obtain pure isolates, characterization by using infrared spectrophotometer (IR) and UV-VIS spectrophotometer then following biological test. The isolates obtained were tested positive for phytochemical containing alkaloid compounds and characterized as amorphous crystals. Identification of IR spectrophotometer generate a functioning -NH wave group of the wavelengths region of 3423.4 cm-1, bend C-N at wave number 1242.1 cm-1, C-H stretch at wave number 2925.8 and 2854.5 cm-1, bend C-H at 1475 wave numbers 1540 cm-1, carbonyl group (C = O) at the 1720.4 cm-1 wave number which is probably an alkaloid compound. The UV-VIS spectrophotometer results in a maximum absorption at 209.9 nm wavelengths indicated the presence of double bonds between the C = O functional group suspected as a result of the successive electronic transitions to n-π * and n-σ *. The result of biological test showed that methanol extracts of tombili seed can be used as a vegetable pesticide in pest prevention on rice plants, the most effective concentration used in this biological test is at 0.1% concentration, with very high effectiveness in eradicating pest on rice plants.

Phase behavior of ASDs based on hydroxypropyl cellulose

Novel polymeric carriers for amorphous solid dispersions (ASDs) are highly demanded in pharmaceutical industry to improve the bioavailability of poorly-soluble drug candidates. Besides established polymer candidates, hydroxypropyl celluloses (HPC) comes more and more into the focus of ASD production since they have the availability to stabilize drug molecules in aqueous media against crystallization. The thermodynamic long-term stability of HPC ASDs with itraconazole and fenofibrate was predicted in this work with PC-SAFT and compared to three-months enduring long-term stability studies. The glass-transition temperature is a crucial attribute of a polymer, but in case of HPC hardly detectable by differential scanning calorimetry. By investigating the glass transition of HPC blends with a miscible polymer, we were for the first time able to estimate the HPC glass transition. Although both, fenofibrate and itraconazole reveal a very low crystalline solubility in HPC regardless of the HPC molecular weight, we observed that low-molecular weight HPC grades such as HPC-UL prevent fenofibrate crystallization for a longer period than the higher molecular weight HPC grades. As predicted, the ASDs with higher drug load underwent amorphous phase separation according to the differential scanning calorimetry thermograms. This work thus showed that it is possible to predict critical drug loads above which amorphous phase separation and/or crystallization occurs in HPC ASDs.

Spray Synthesis of Photonic Crystal Based Automotive Coatings with Bright and Angular‐Dependent Structural Colors

AbstractIt is a challenge to prepare photonic crystal (PC) automotive coatings via spraying colloidal solutions because the fast fabrication tends to produce amorphous photonic crystals with faint colors. Here, a two‐step spraying process followed by thermal curing is developed to prepare waterproof PC coatings with bright, uniform, and angular‐dependent structural colors. The solvents in PC paint are studied to achieve a quick formation of liquid PC intermediate, which transformed into a highly crystalline PC coating. Thanks to the narrow and intense reflections, the as‐made coatings present colors with high saturation, including the red/yellow/green/blue colors achieved by tuning the particle size, and many spectral/non‐spectral colors via the mixing of base colors. Meanwhile, patterned or fully covered PC coatings with good chemical and mechanical stability can be prepared on different substrates, where the shiny colors changing with the viewing angles or the surface curvatures offer a new choice for personalized automotive coatings.

Adjustable color and emissivity based on amorphous arrays composed of SiO2@ZnO

SiO2@ZnO amorphous photonic crystals (APCs) were mainly manufactured by cladding and self-assembling. In this work, the SiO2 APCs framework are contributed to the desired structural color and the coated ZnO particles are served for reducing the infrared emissivity in 3–5 µm waveband. The effects of SiO2 particle size and ZnO adhesion amount on the visible light properties have been investigated as well as the infrared performance. The results show that with the diminution of SiO2 particles size, the packing quality of SiO2@ZnO is constantly improved since the smaller particle possesses higher electric density and surface energy. In the effects of nuclei size, SiO2@ZnO APCs with different size of building units display different color and low emissivity, and the sample with 250 nm core and 1:2 SiO2/ZnO mass ratio has blue structure and emissivity of 0.303. Meanwhile, the increasing ZnO adhesion amount can also alter the structural color due to the red shift of photonic pseudogap, and the minimum emissivity values keep dropping from 0.496 to 0.236. Finally, the SiO2@ZnO APCs with SiO2 core size of 250 nm and SiO2/ZnO mass ratio of 1:4 exhibit prominent performance with light green and low emissivity of 0.236 which contributes to the compatibility in green vegetation camouflage background and infrared stealth.

Critical point of jamming transition in two-dimensional monodisperse systems.

The existence of amorphous packings in two-dimensional monodisperse system is a classical unsolved problem. We get the energy minimum state by the energy minimization method of enthalpy under constant pressure conditions. Firstly, we find that there are two peaks in the experiment, which demonstrate the interesting features of the coexistence of crystals and amorphous crystals. And then, we confirm the critical point of jamming transition of the two-dimensional monodisperse is [Formula: see text]. Finally, we prove that the jamming scaling is still satisfied in two-dimensional monodispersed system: [Formula: see text] and vanishes as [Formula: see text], and the boson peak shifts to lower frequencies for less compressed systems.