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11.
12.
Alpha-phenylethanol (PE) is an essential chemical in the field of medicine and synthetic perfumery. Therefore, in this work, we used a supported Ni–B–P amorphous alloy catalyst (Ni–B–P/SiO2) in the hydrogenation of acetophenone (AP) to α-PE, which demonstrated excellent catalytic activity and selectivity, compared with Ni–B/SiO2 (KBH4 reduction of nickel salt). Ni–B–P/SiO2 exhibited a high AP hydrogenation conversion of approximately 99%, whereas the PE selectivity reached up to 94%, which is approximately 1.4-fold higher than that of Ni–B/SiO2 (about 69%), thereby directly proving the unique inhibition of AP hydrogenation over hydrogenation of P in the Ni–B catalytic system. The doped P in Ni–B–P/SiO2 enhances the oxidation resistance and maintains the valence stability of Ni and B. Furthermore, sufficient experimental data were collected to determine the kinetic parameters. Based on the Langmuir–Hinshelwood model, we assumed that (i) AP and H2 compete for adsorption on Ni–B–P/SiO2; (ii) AP has strong adsorptive capacity on Ni–B–P/SiO2; and (iii) PE coverage on the catalyst was negligible. Then, the dynamic equation was derived, which indicated that experimental data agree well with the dynamic model. Finally, the activation energy was confirmed to be 50.73 KJ/mol. This report will open up an avenue for the industrialization of amorphous alloy catalysts. 相似文献
13.
基于Lagoudas形状记忆合金(SMA)三维本构模型,假设材料为各向同性,推导了SMA平面应力状态的增量型本构方程,继而编写了ABAQUS用户自定义材料(UMAT)子程序,研究了在双向拉伸情况下,外载荷、温度、椭圆孔口长短轴之比对超弹性SMA椭圆孔口板中应力诱发马氏体相变区的影响。数值结果表明:应力诱发马氏体相变首先发生在椭圆孔口长轴端点部位,在外加载荷作用下逐渐扩展到板内,并由内向外形成马氏体相区、相变混合区和奥氏体相区;SMA板内应力诱发马氏体完全相变区面积与施加外载荷成正相关,与温度成负相关;随着椭圆孔口长短轴之比增大,SMA板内应力诱发马氏体完全相变区面积呈现出先减小后增大的趋势;拉应力差值相同时,相较于拉应力沿椭圆孔口长轴方向较大的情况,当拉应力沿椭圆孔口短轴方向较大时,SMA板内完全相变区面积较大,椭圆孔口周边应力集中现象更明显。 相似文献
14.
Recent research has focused on increasing the evidentiary value of latent fingerprints through chemical analysis. Although researchers have optimized the use of organic and metal matrices for matrix‐assisted laser desorption/ionization‐mass spectrometry imaging (MALDI‐MSI) of latent fingerprints, the use of development powders as matrices has not been fully investigated. Carbon forensic powder (CFP), a common nonporous development technique, was shown to be an efficient one‐step matrix; however, a high‐resolution mass spectrometer was required in the low mass range due to carbon clusters. Titanium oxide (TiO2) is another commonly used development powder, especially for dark nonporous surfaces. Here, forensic TiO2 powder is utilized as a single‐step development and matrix technique for chemical imaging of latent fingerprints without the requirement of a high‐resolution mass spectrometer. All studied compounds were successfully detected when TiO2 was used as the matrix in positive mode, although, generally, the overall ion signals were lower than the previously studied CFP. TiO2 provided quality mass spectrometry (MS) images of endogenous and exogenous latent fingerprint compounds. The subsequent addition of traditional matrices on top of the TiO2 powder was ineffective for universal detection of latent fingerprint compounds. Forensic TiO2 development powder works as an efficient single‐step development and matrix technique for MALDI‐MSI analysis of latent fingerprints in positive mode and does not require a high‐resolution mass spectrometer for analysis. 相似文献
15.
Niloofar Seydi Behnam Mahdavi Sogand Paydarfard Akram Zangeneh Mohammad Mahdi Zangeneh Fariba Najafi Ali R. Jalalvand Elham Pirabbasi 《应用有机金属化学》2019,33(9)
In recent decades, nanotechnology is growing rapidly owing to its widespread application in science and industry. The aim of the experiment was chemical characterization and evaluation of cytotoxicity, antioxidant, antibacterial, antifungal, and cutaneous wound healing activities of titanium nanoparticles using aqueous extract of Ziziphora clinopodioides Lam leaves (TiNPs@Ziziphora). These nanoparticles were characterized by fourier transformed infrared spectroscopy (FT‐IR), field emission scanning electron microscopy (FE‐SEM), energy dispersive X‐ray spectroscopy (EDS), and UV–visible spectroscopy. The synthesized TiNPs@Ziziphora had great cell viability dose‐dependently (Investigating the effect of the plant on human umbilical vein endothelial cells (HUVECs) cell line) and revealed this method was nontoxic. Then, 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical scavenging test was done to assess the antioxidant properties, which indicated similar antioxidant potentials for TiNPs@Ziziphora and butylated hydroxytoluene. Agar diffusion tests were applied to determine the antibacterial and antifungal characteristics. Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Minimum Fungicidal Concentration (MFC) were specified by macro‐broth dilution assay. The data were analyzed by SPSS 21 software (Duncan post‐hoc test). TiNPs@Ziziphora indicated higher antibacterial and antifungal effects than all standard antibiotics (p ≤ 0.01). Also, TiNPs@Ziziphora inhibited the growth of all bacteria at 2‐16 mg/ml concentrations and removed them at 2‐32 mg/ml concentrations (p ≤ 0.01). In case of antifungal properties of TiNPs@Ziziphora, they prevented the growth of all fungi at 2‐8 mg/ml concentrations and destroyed them at 2‐16 mg/ml concentrations (p ≤ 0.01). In vivo experiment, after creating the cutaneous wound, the rats were randomly divided into six groups: untreated control, treatment with Eucerin basal ointment, treatment with 3% tetracycline ointment, treatment with 0.2% TiO2 ointment, treatment with 0.2% Z. clinopodioides ointment, and treatment with 0.2% TiNPs@Ziziphora ointment. These groups were treated for 10 days. For histopathological and biochemical analysis of the healing trend, a 3 × 3 cm section was prepared from all dermal thicknesses at day 10. Use of TiNPs@Ziziphora ointment in the treatment groups substantially reduced (p ≤ 0.01) the wound area, total cells, neutrophil, and lymphocyte and remarkably raised (p ≤ 0.01) the wound contracture, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte, and fibrocytes/fibroblast rate compared to other groups. In conclusion, the results revealed the useful non‐cytotoxic, antioxidant, antibacterial, antifungal, and cutaneous wound healing effects of TiNPs@Ziziphora. 相似文献
16.
Franziska Kühn 《Mathematische Nachrichten》2019,292(2):358-376
We present an existence result for Lévy‐type processes which requires only weak regularity assumptions on the symbol with respect to the space variable x. Applications range from existence and uniqueness results for Lévy‐driven SDEs with Hölder continuous coefficients to existence results for stable‐like processes and Lévy‐type processes with symbols of variable order. Moreover, we obtain heat kernel estimates for a class of Lévy and Lévy‐type processes. The paper includes an extensive list of Lévy(‐type) processes satisfying the assumptions of our results. 相似文献
17.
Jamil Chaker 《Mathematische Nachrichten》2019,292(11):2316-2337
We consider systems of stochastic differential equations of the form for with continuous, bounded and non‐degenerate coefficients. Here are independent one‐dimensional stable processes with . In this article we research on uniqueness of weak solutions to such systems by studying the corresponding martingale problem. We prove the uniqueness of weak solutions in the case of diagonal coefficient matrices. 相似文献
18.
Mohammad Nasir Uddin Zainul Abedin Siddique Nobuyuki Mase Monir Uzzaman Wahhida Shumi 《应用有机金属化学》2019,33(6)
A number of oxotitanium(IV) complexes of the type TiOL with bis‐unsymmetric dibasic tetradentate Schiff base (LH2) containing ONNO donor atoms have been synthesized. Mono‐Schiff base (OPD‐HNP) was prepared by the condensation of 1:3 molar ratio of 2‐hydroxy‐1‐naphthaldehyde (HNP) with o‐phenylenediamine (OPD). Dibasic unsymmetric tetradentate diamine Schiff bases were prepared by the reaction of OPD‐HNP with 2‐hydroxyacetophenone, 2‐hydroxypropeophenone, benzoylacetone, acetylacetone and ethylacetoacetate. Further, titanylacetylacetonate was reacted with these ligands to obtain their metal complexes. On the basis of analytical and physiochemical data, the formation of complexes as TiOL was suggested having square pyramidal geometry. Quantum mechanical approach also confirmed this geometry. The assessment of the synthesized ligands and their complexes showed that some behave as good inhibitors of mycelial growth against selected phytopathogic fungi but weak inhibitors against some selected bacteria. A few of them also showed antioxidant properties. 相似文献
19.
We provide new closed‐form approximations for the pricing of spread options in three specific instances of exponential Lévy markets, ie, when log‐returns are modeled as Brownian motions (Black‐Scholes model), variance gamma processes (VG model), or normal inverse Gaussian processes (NIG model). For the specific case of exchange options (spread options with zero strike), we generalize the well‐known Margrabe formula (1978) that is valid in a Black‐Scholes model to the VG model under a homogeneity assumption. 相似文献
20.
For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates. 相似文献