The goal of this study is to develop a high magnetic flux density and low iron loss powder magnetic core with insulated layer coating on pure iron powders of varying sizes. After processing the ...phosphate treatment, the insulated layer Zn3(PO4)2 was coated onto the iron powder surface. It not only maintained the magnetic flux density of pure iron, but also enhanced the electrical resistivity of the magnetic core by reducing eddy current loss, which allowed a wider frequency range. In addition, the annealing treatment after the compression process raised the magnetic flux density of the magnetic core; however, an annealing temperature above 200°C caused the binder to decompose, resulting in decreased electrical resistivity. Experimental results indicate that the best magnetic performances were achieved with a powder magnetic core of fine and coarse iron powder proportion of 2:1, phosphate treatment of 90s, and an annealing temperature of 200°C.
•Two iron powders of different sizes were mixed together to fabricate the powder magnetic core in this study.•The resistivity of the powder magnetic core increased with an increasing phosphate treatment duration.•The influence of annealing temperature on the magnetic performance of the magnetic core was discussed.•A high magnetic flux density and low iron loss powder magnetic core was developed.
An efficient method was developed for the one-pot construction of C-B and C-I
via
visible light-induced transformation of nitroarenes. This protocol relies on the photochemical properties of ...nitroarenes under visible light, followed by reduction with B
2
pin
2
and diazotization with
t
BuONO. An array of arylboronates and iodobenzenes were constructed smoothly after excitation with purple LEDs at room temperature. In addition, the synthetic utility of this method was further demonstrated in the late-stage modification of a drug molecule. The advantages of this strategy include metal-free system, mild reaction conditions and acceptable substrate scope.
A simple, efficient, green method for converting nitroarenes into haloarenes and arylboronates under light irradiation.
A flame-retardant and superhydrophobic coating was applied to cotton textiles by a conventional pad-dry-cure method, which involved the deposition of branched poly(ethylenimine), polyacrylate ...soap-free latex and ammonium polyphosphate. The as-coated fabrics showed superhydrophobicity with a self-cleaning effect, and the fibers could generate a char layer in the flame-burning test, giving the fabrics a self-extinguishing property. Importantly, the resulting fabrics remained superhydrophobic after 75 commercial laundering cycles. The advantages of this method are being simple, affordable and easy to use in the factory production of large quantities of multifunctional textiles.
The present work critically investigates the fabrication of metal contacts to advanced applications of bismuth-based oxide glass and screen-printed silver contacts for use in integrated circuits ...(I.C.s), solar cells, and sensors. Electrode contacts were fabricated by screen printing composite pastes composed of mainly silver powder, Bi2O3 glass powder, and acyclic binder, and then firing the pastes in a belt furnace. The composite films' microstructures after firing at 830–890 °C were observed under various corrosion conditions, and the resulting layers were analyzed with X-ray diffraction (XRD) and the transfer length method (TLM). A series of investigations to determine the influence of Bi2O3 glass in silver paste involved differential thermal analysis (DTA), scanning electron microscopy (SEM), electron probe X-ray microanalysis (EPMA), secondary ion mass spectrometry (SIMS), and transmission electron microscopy (TEM), to determine the effects of Bi2O3 mixed with silver and the efficacy of the resulting metal contacts in I.C. fabrications. Results show that increasing firing temperature and the additive of Bi2O3 glass controlled the silver's melting into the glass and influenced Ag crystallites' precipitation.
Display omitted
•The influence of the Ag crystallites' size in Bi2O3 glass are studied.•The contact resistance of the silver layer and a single silver crystal is measured.•The coated layer by layer microstructure was identified.
Hydrophobic polydimethylsiloxane based coatings were self-roughened on textiles viaa nonsolvent-induced phase-separation method. The self-roughened coatings have superior durability in ...superhydrophobicity. The obtained superhydrophobic and superoleophilic materials were demonstrated as excellent filters for continuous oil-water separation. The work showed large-scale and practical application for consecutive collection of oil from water.
The development of a novel environmental benign and sustainable synthetic method for highly efficient construction and direct C–H functionalization of N-heterocycles remains a pivotal central ...research topic for organic and medicinal chemistry. Herein, a novel visible-light-enabled biomimetic aza-6π electrocyclization for efficient assembly of diverse pyridines and further tandem Minisci-type reaction were developed. A broad spectrum of polysubstituted picolinaldehydes were readily constructed with high efficacy and good functional group tolerance under metal- and oxidant-free conditions.
► Optimizing the silver paste in 80–85wt.%. ► Optimizing its particle size in 1–1.5μm spherical powder. ► The sheet resistance is 4mΩ/sq during the 860°C sintering process. ► Redox reaction cause Ag ...crystallites to grow on the interface. ► A thin layer of silicon oxide (75–150nm) was formed.
Since the silver paste plays a major role in the mass production of silicon solar cells, this work has succeeded in optimizing the silver paste in 80–85 wt.% and optimizing its particle size in 1–1.5μm spherical powder. As the firing temperature is increased, the growth trend of silver grain is improved. The result of this work has showed that the lowest sheet resistance is 4mΩ/sq during the 860°C sintering process. The scanning electron microscope (SEM) observation has showed that the formation of silver oxide is formed during the melting process of glass and triggered redox reaction of Ag crystallites to grow on the interface. It has proven by transmission electron microscope (TEM) that a thin layer of silicon oxide (75–150nm) was formed, respectively.
In this study, we synthesized standing 2D δ‐Cu2Te flakes (δ‐CTFs) via a facile post‐tellurization process, which served as the current collector to accommodate zinc (Zn) for AZIBs. These flakes ...exhibited low nucleation overpotential and low interfacial impedance, facilitating the plating/stripping of Zn ions. Interestingly, the hydrophilicity and standing structure of δ‐CTFs guided the electrodeposited Zn to laterally grow on the surface of δ‐CTFs, effectively suppressing Zn dendrite formation. The Zn@δ‐CTFs anode exhibited a long‐term cycling duration of 510 hours in a symmetric cell, which is far superior to previous reports. Even under high current density of 10 mA cm−2, the anode was able to perform stably with a cycle life of 110 hours. The machine learning model was exploited to predict the effective charge value, discovering that Zn migrated in Cu2Te were subject to the larger driving force of migration under applied field. Finally, the Zn@δ‐CTFs//MnO2 full battery exhibited excellent rate‐dependent capacity and maintained a capacity of 100 mAh g−1 after 1000 cycles at a current density of 1 A g−1, without Zn dendrite formation. This research provides a new strategy for regulating Zn deposition to address dendrite issues toward long lifespan AZIBs.
Zincophilic δ‐Cu2Te flakes (δ‐CTFs) synthesized via the post‐tellurization process is exploited as a current collector for aqueous zinc‐ion batteries (AZIB). Benefitting from the zincophilicity and 3D structuring surface, Zn@δ‐CTFs symmetric cells delivered the long lifespan up to 510 hours under the the ZUR of 10 %. Finally, the full cells displayed the initial specific capacity of 210 mAh g−1 and retained 170 mAh g−1 after 300 cycles. The work provides a new strategy for guiding the Zn electrodeposition to suppress the dendrite growth toward the high‐performance AZIB.
To explore the diagnostic performance of blood urea nitrogen-to-creatinine (BUN/Cr) ratio in differentiating the site of gastrointestinal bleeding, and to assess the predictive value of early ...elevated BUN/Cr ratio for clinical outcomes in patients with acute nonvariceal upper gastrointestinal bleeding (ANVUGIB).
The adult patients diagnosed with gastrointestinal bleeding who were hospitalized in the Department of Gastroenterology, Zhongshan Hospital, Xiamen University between May 2020 and May 2021 were retrospectively enrolled. According to the site of gastrointestinal bleeding, the patients were divided into the upper gastrointestinal tract group, the proximal small intestinal bleeding group, and the distal small intestinal and colonic bleeding group. According to the early dynamic changes of BUN/Cr ratio within 6-48 hours after admission, patients with ANVUGIB were divided into early dynamic elevated BUN/Cr ratio group and non-early dynamic elevated BUN/Cr ratio group. Receiver operating characteristic (ROC
PDF
