Preparation and characterization of nickel hydroxide microspheres assembled by nanoribbons

Abstract  

This article describes a facile green strategy for preparing the Ni(OH)₂ microsphere assembled by nanoribbons by the template of the squama inner coat of onion at mild condition. The method is simple and effective. The results of SEM show the products are Ni(OH)₂ microspheres with diameters in the range of 500–2,500 nm. The results of TEM show the microsphere is assembly by nanoribbons, with thickness in the range of 30–50 nm. The products were characterized by powder X-ray diffraction, IR, and thermogravimetric analysis. A possible formation mechanism was also proposed.     

One-step synthesis and antibacterial property of water-soluble silver nanoparticles by CGJ bio-template

In this article, a new synthetic method of nanoparticles with fresh Chinese gooseberry juice (CGJ) as bio-template was developed. One-step synthesis of highly water-soluble silver nanoparticles at room temperature without using any harmful reducing agents and special capping agent was fulfilled with this method. In the process, the products were obtained by adding AgNO₃ to CGJ, which was used as reducing agent, capping agent, and the bio-template. The products of silver nanoparticles with diameter of 10–30 nm have strong water solubility and excellent antibiotic function. With the same concentration 0.047 μg mL⁻¹, the antibacterial effect of water-soluble silver particles by fresh CGJ was 53%, whereas only 27% for silver nanoparticles synthesized using the template method of fresh onion inner squama coat (OISC). The excellent water solubility of the products would enable them have better applications in the bio-medical field. The synthetic method would also have potential application in preparing other highly water-soluble particles, because of its simple apparatus, high yield, mild conditions, and facile operation.     

Reducing the formation of six-membered ring ester during thermal degradation of biodegradable PHBV to enhance its thermal stability

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has attracted the attention of academia and industry because of its biodegradability, biocompatibility, thermoplasticity and plastic-like properties. However, PHBV is unstable above 160 °C during melt processing at a temperature above the melting temperature, which restricts practical applications as a commodity material. It is widely believed that thermal degradation of PHBV occurs almost exclusively via a random chain scission mechanism involving a six-membered ring transition state. Here, 2,2′-bis(2-oxazoline) (BOX) was selected to modify PHBV to control the formation of six-membered ring ester during thermal degradation. The resulting hydroxyl-terminated PHBVs (HT-PHBVs) had improved thermal stability due to a decrease in the negative inductive effect of the neighboring group of methylene groups at the β-position to the ester oxygen, and a decrease in the electron-denoting effect of substituent group of carbon atoms at α-position to the ester oxygen. The optimal reaction temperature and time were determined to be 95 °C and 6 h, respectively. Compared with those of original PHBV, the temperature determined at 5% weight loss (T_5%), the initial decomposition temperature (T₀), the maximum decomposition temperature (T_max), the complete decomposition temperature (T_f) of HT-PHBV prepared under the optimal conditions increased by 31, 24, 19 and 19.1 °C, respectively.     

Antiviral Effects of Green Tea EGCG and Its Potential Application against COVID-19

(–)-Epigallocatechin-3-O-gallate (EGCG), the most abundant component of catechins in tea (Camellia sinensis (L.) O. Kuntze), plays a role against viruses through inhibiting virus invasiveness, restraining gene expression and replication. In this paper, the antiviral effects of EGCG on various viruses, including DNA virus, RNA virus, coronavirus, enterovirus and arbovirus, were reviewed. Meanwhile, the antiviral effects of the EGCG epi-isomer counterpart (+)-gallocatechin-3-O-gallate (GCG) were also discussed.     

Theory studies of the local lattice distortions and the EPR parameters for Cu2+, Mn2+ and Fe3+ centres in ZnWO4

The local lattice distortions and the electron paramagnetic resonance (EPR) parameters (g factors, hyperfine structure constants and zero-field splittings) for Cu²⁺, Mn²⁺ and Fe³⁺ in ZnWO₄ are theoretically studied based on the perturbation calculations for rhombically elongated octahedral 3d⁹ and 3d⁵ complexes. The impurity centres on Zn²⁺ sites undergo the local elongations of 0.01, 0.002 and 0.013 Å along the C₂ axis and the planar bond angle variations of 8.1°, 8.0° and 8.6° for Cu²⁺, Mn²⁺ and Fe³⁺, respectively, due to the Jahn–Teller effect and size and charge mismatch. In contrast to the host Zn²⁺ site with obvious axial elongation (～0.31 Å) and perpendicular (angular) rhombic distortion, all the impurity centres demonstrate more regular octahedral due to the above local lattice distortions. The copper centre exhibits significant Jahn–Teller reductions for the spin-orbit coupling and orbital angular momentum interactions, characterised by the Jahn–Teller reduction factor J (≈0.29 ? 1). The calculated EPR parameters agree well with the experimental results. The local structures of the impurity centres are analysed in view of the corresponding lattice distortions.     

Preparation, structures and photoluminescent enhancement effect of PbWO4–TiO2 composite nanofilms

A novel route for preparing PbWO₄–TiO₂ nanofilms on a glass substrate is firstly proposed. The collodion is used as a dispersant and film-forming agent. The nanofilms are characterized through SEM, XRD, TG/DTA, PL and IR, respectively. The results of XRD indicate PbWO₄ particles with tetragonal scheelite structure and TiO₂ particles with Anatase phase, and SEM shows they are well dispersed in the substrate. Compared with nanoparticles, when TiO₂ nanoparticles are added in 5% ratio, the PL intensities at 395 nm of PbWO₄ nanofilms are enhanced obviously. IR spectrum reveals a large absorption band between 750 and 870 cm⁻¹, which is the W–O stretching vibration in WO₄ tetrahedron.     

Cu/SO42-/La2O3-ZrO2-Al2O3催化剂的制备及其对C3H6选择还原NO的催化性能

以Al₂O₃为基质，添加ZrO₂和La₂O₃，制成La₂O₃-ZrO₂-Al₂O₃复合载体，然后采用SO₄^2-进行改性，再负载上Cu²⁺，制备了铜基SO₄^2-改性的复合载体催化剂(Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃)。考察了它在富氧条件下对丙烯选择还原NO的催化性能，并借助XRD、SEM、TG、Py-IR、NH₃-TPD、FTIR和TPR等方法研究了Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃的结构和性能的关系。结果表明，ZrO₂的加入主要有利于提高催化剂的低温活性；La₂O₃的加入则主要有利于提高催化剂的热稳定性和还原性能；SO₄^2-能够与Zr形成螯合双配位结构，大幅度促使催化剂表面酸量增加并且酸性增强；因此，有效地提高了Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃在富氧条件下对丙烯选择还原NO的催化活性和水热稳定性。在无水条件下，Cu/SO₄^2-/La₂O₃-ZrO₂-Al₂O₃能使NO的最大转化率高达84.3%，即使在275 ℃ 10%水蒸气存在的情况下，仍能使NO的转化率高达81.2%。     

Synthesis and Design of MnCO<Subscript>3</Subscript> Crystals with Different Morphologies by Supported Liquid Membrane

Abstract  A biomimetic supported liquid membrane (SLM) system was employed to control the morphology of manganese carbonate. Some interesting morphologies including nanowire/hollow spheres/twinborn spheres could be readily generated by using EDA (ethylenediamine), EDTA (ethylenediaminetetracid) or NTA (nitrilotriacetic acid) as cooperative modifiers in the mineralization process, under the conditions of pH 10, 0.01% of crystal modifier and ambient temperature. The key factor in this system was the cooperative template effect of SLM and the crystal modifiers. The clarification of fantastic morphogenesis of them could be valuable for understanding of biomineralization processes. Index Abstract  A biomimetic supported liquid membrane (SLM) system was employed to control the morphology of manganese carbonate. Some interesting results including nanowires/hollow spheres/twinborn spheres/etc. could be readily generated by using EDA (ethylenediamine), EDTA (ethylenediaminetetracid) or NTA (nitrilotriacetic acid) as cooperative modifiers in the mineralization process. The clarification of fantastic morphogenesis of them could be valuable for the understanding of biomineralization processes..      

分布式冷热电三联供系统的单耗分析模型研究

基于"单耗分析"理论,建立了针对燃料为天然气的分布式冷、热、电三联产系统的常见运行模式下的多热源、多冷源的燃料单耗模型和成本单耗模型.利用该模型进行了案例计算,结果清楚地表明了系统各个环节燃料附加单耗的分布.通过对计算结果的分析,得出了一些有益的结论.     

Facile synthesis of monodisperse silver nanoparticles by bio-template of squama inner coat of onion

This paper describes a facile sy]nthetic method for preparing monodisperse silver nanoparticles by bio-template of the squama inner coat of onion. The method is able to make silver nanoparticles with average diameters in the range of 4.6–7.9 nm with narrow size distribution. The important factors in the synthesis of monodisperse silver nanoparticles were discussed. The nanoparticles were characterized by transmission electron microscope, Powder X-ray diffraction and UV-Vis spectroscopy. A possible formation mechanism was also proposed. Because of its simple apparatus, high yield, convenient operation and mild conditions, this synthetic method will have potential application in preparing nanoparticles.