Search

Promoting safe tires with low external rolling noise increases the environmental efficiency of road transport. Although tire builders have been striving to reduce emitted noise, the issue's sophisticated nature has made it difficult. This article aims to make the problem straightforward, relying on recent significant improvements in statistical science. In this regard, the prediction ability of new methods in this field, including support vector machine, relevance vector machine, and convolutional neural network, along with the new architecture of the neural network is compared. Tire noise is measured under the coast-by condition. Two training strategies are proposed: extracting features from a tread pattern image and directly importing an image to the model. The relevance vector method, which is trained using the first strategy, has provided the most accurate results with an error of 0.62 dB(A) in predicting the total noise level. This precise model is used instead of experimentation to analyze the sensitivity of tire noise to its parameters using a small central composite design. The parametric study reveals striking tips for reducing noise, especially in terms of interactions between parameters that have not previously been shown. Finally, a novel two-stage approach for reducing noise by tread pattern optimization is proposed, inspired by two regression models derived from statistical investigation and variance analysis. Changes in tread pattern specifications of two case studies and their randomization have resulted in a reduction of 3.2 dB(A) for a high-noise tire and 0.4 dB(A) decrement for a quieter tire. [ABSTRACT FROM AUTHOR]

In the present study, a hollow MgO/SiO2 nanocatalyst with high alkaline properties was prepared. This heterogeneous catalyst was prepared in several steps to create a great active area and decrease the density of the catalyst. The alkaline hollow catalyst framework was applied for the reaction of cyclohexanone, malononitrile and benzaldehyde for synthesis of 1 H-isocromene therough the Michael addition and aldol condensation reaction at room temperature. In this method, all of the done reactions were excellent in the yields of products and reaction times. At the end of the reaction, the nanocatalyst separated by simple filtration and reuse in several runs elsewhere. In the present study, hollow MgO/SiO2 nanocatalyst with great base properties was made. Thisheterogeneous catalyst was a synthesis in several steps to create a great active area and decreasethe density of the catalyst [ABSTRACT FROM AUTHOR]

Prediction and reduction of tire noise are some of the main concerns of tire designers nowadays. Due to tire noise's sophisticated nature, low-noise tire design is like a maze path improbable to achieve without a scientific understanding of the underlying causes. This paper develops a knowledge-based hybrid model, incoherent summation of sounds generated and amplified by texture impact, tread impact, air-pumping, Helmholtz resonance, pipe resonance, horn effect, and air cavity resonance. The required data have been carried out by measuring C1 radial tires' noise levels in a semi-anechoic chamber. The developed model [with about a 1.7 dB(A) error on total noise prediction] presents mechanisms' contributions to the overall sound. The model is substituted with a fast-computing statistical model employing data generated based on Taguchi design. Machine learning methods are implemented for this aim, and the support vector machine provides the most accurate model. The proposed fast-computing hybrid model, developed based on a scientific description of underlying mechanisms, is applicable for noise reduction. The model's sensitivity to 21 tire parameters is analyzed, leading to valuable tips on lower tire noise. The results show the critical role of tread pattern characteristics, especially groove angle, in tire noise. [ABSTRACT FROM AUTHOR]

(6R)-1-((3S)-3'-Amino-6-chloro-2',2'-dicyano-2-oxo-7'-propyl-6',7',8',8a'-tetrahydro-2'h-spir... 0.73 g, 88% yield, 35 min, white solid; m.p.: 237-239 °C, IR (KBr): v = 3663, 3553, 3372, 3216, 2908, 2856, 2216, 1743, 1662, 1589, 1475, 1431, 1289, 1184, 1098, 1015, 832, 651, 606 cm SP -1 sp ; SP 1 sp H NMR (400 MHz, DMSO-d6) 10.84 (s, 2H, NH,NH), 8.34 (s, 1H, NH), 7.87 (s, 2H, CH, NH), 7.28 (s, 2H, NH2), 6.76-7.14 (m, 6H), 5.77 (s, 1H), 4.12 (s, 1H), 2.50 (s, 3H), 1.50 (s, 6H), 1.05-1.18 (d, J = 53.6 Hz, 9H), 0.79 (s, 6H), 0.16 (s, 2H); SP 13 sp C{ SP 1 sp H} NMR (100 MHz, DMSO I d i SB 6 sb ) 173.9, 173.70, 158.4, 156.8, 156.8, 148.8, 147.1, 141.2, 131.0, 129.5, 129.1, 127.0, 126.7, 126.2, 126.0, 125.9, 125.75, 122.7, 121.3, 120.7, 116.8, 116.6, 115.6, 114.8, 110.9, 110.6, 81.3, 80.6, 54.8, 53.8, 52.85, 39.8, 39.6, 38.6, 38.4, 38.1, 38.1, 37.4, 29.8, 19.2, 14.0; MS (EI), m/z (%) = 835 ([M] SP + sp , 0.8), 834 (1.5), 444 (24), 412 (67),392 (26), 323 (36), 308 (38), 187 (50), 166 (64), 114 (45), 77 (30), 58 (60), 41 (100). [Extracted from the article]

In this research, it was displayed an efficient method for the one‐pot reaction of cyclohexanone, benzaldehyde and malononitrile for the synthesis of 4H‐chromenes by using CoFe2O4/lamellar mesopore silica anchored to melamine as a magnetic nanocatalyst. This nanocatalyst was prepared in several steps and discriminated by XRD, FT‐IR, SEM, VSM, TGA and BET techniques. The catalyst has a large active base site that has functionalized in both the surface and the pore of nanostructure. The advantages of magnetic nanocatalyst were simple accessible, heterogeneous nanocatalyst, easy work up and reusability. The various derivatives of 4H‐chromenes were synthesized in the presence of CoFe2O4/lamellar mesopore silica/melamine magnetic nanocatalyst with the excellent yields and appropriate times. The products were identified by the melting point, FT‐IR, 1H NMR, 13C NMR and C.H.N techniques. [ABSTRACT FROM AUTHOR]

Designing protocols for the preparation of nanocatalyst in order to increase the yield of an organic reaction is a challenging task in modern chemistry. CaMgFe2O4 is a base nanocatalyst that prepared through sol‐gel method. This nanocatalyst has used for the synthesis of 1H‐isocromenes, 4H‐chromenes and ortho‐aminocarbonitrile tetrahydronaphthalenes through the multi‐component reactions. The starting materials for all of the reactions are cyclohexanone, benzaldehyde and malononitrile and the reaction followed with Michael addition and cyclization. Therefore, the different multicomponent reactions from the same materials arranged by using CaMgFe2O4 base nanocatalyst. The catalyst identified with XRD, EDX, SEM, VSM and XPS techniques and the organic compounds recognized with melting point, FT‐IR, 1H NMR and 13C NMR analyses. [ABSTRACT FROM AUTHOR]

A facile and rapid multicomponent synthesis of pharmaceutically diverse 1H‐isochromenes, 4H‐chromenes, and ortho‐aminocarbonitrile tetrahydronaphthalenes has been developed from benzaldehyde, malononitrile, and cyclohexanone. Three different methods from the same reactants, solvent, temperature, and catalyst lead to three products with excellent yields. All the reactions were followed with the Michael addition and cyclization. In this study, morpholine was used as an active metal‐free base catalyst that increases the yields of products and decreases the time of reactions. [ABSTRACT FROM AUTHOR]

Aim: To investigate the relation between the circadian rhythm amplitude and stability, and occupational stress with burnout syndrome and job dissatisfaction among shift working nurses. Background: Irregular shift working nurses are prone to burnout syndrome (BS) and job dissatisfaction (JD). circadian rhythm difference and occupational stress might be effective in causing burnout syndrome and dissatisfaction. Design: In total, 684 nurses who worked in four teaching hospitals were selected by stratified random sampling in a cross‐sectional design based on STROBE guidelines. Methods: The data were collected by the Circadian Type Inventory, Job Content Questionnaire, Minnesota Satisfaction Questionnaire and the Maslach Burnout Inventory. Multiple linear regression, one‐way ANOVA and independent t test were used for statistical analysis by SPSS v24. Results: About 15% of the nurses suffered from high levels of burnout syndrome. Psychological demand (β = 0.022, CI 95% = 0.003‒0.047 and β = 0.016, CI 95% = 0.001‒0.032) and workplace support (β = −0.043, CI 95% = −0.097–0.003 and β = −0.025, CI 95% = −0.046–0.006) were significant predictors of BS and JD. Male nurses reported lower BS and higher JD compared to female nurses. Irregular shift working schedule was also related to a significantly higher odd of BS (p = 0.009) and JD (p = 0.011). Nurses classified as languid experienced significantly more BS and JD than vigorous nurses. Conclusion: This study shows that BS and JD were strongly associated with psychological demand and workplace support; and vigorous nurses were less prone to BS and JD, and were more suitable for irregular shift work. Relevance to clinical practice: In order to reduce burnout syndrome and job dissatisfaction among irregular shift working nurses, we need to identify the effect of risk factors such as individual differences on the circadian rhythm and job demand which can affect nurses who work in irregular schedules. [ABSTRACT FROM AUTHOR]

A mononuclear complex of Zn(II), [Zn(DIP)2 (DMP)] (NO3)2⋅2H2O in which DIP is 4,7-diphenyl-1,10-phenanthroline and DMP is 4,4'-dimethyl-2,2'-bipyridine has been prepared and characterized by ¹HNMR spectroscopy, FT-IR, UV-Vis and elemental analysis techniques. DNA-binding properties of the complex were studied using UV-vis spectra, circular dichroism (CD) spectra, ?uorescence, cyclic voltammetry (CV), and viscosity measurements. The results indicate that this zinc(II) complex can intercalate into the stacked base pairs of DNA and compete with the strong intercalator ethidium bromide for the intercalative binding sites. [ABSTRACT FROM AUTHOR]

A new mononuclear Pt(II) complex, [Pt(DMP)(DIP)]Cl2.H2O, in which DMP is 4,4-dimethyl-2,2-bipyridine and DIP is 4,7-diphenyl-1,10-phenantroline, has been synthesized and characterized by physicochemical and spectroscopic methods. The binding interaction of this complex with calf thymus DNA (CT-DNA) was investigated using fluorimetry, spectrophotometry, circular dichroism, viscosimetry and cyclic voltametry (CV). UV-VIS spectrum showed 4 nm bathochromic shift of the absorption band at 280 nm along with significant hypochromicity for the absorption band of the complex. The intrnisic binding constant (Kb = 2 x 104 M-1) is more in keeping with intercalators and suggests this binding mode. The viscosity measurements showed that the complex- DNA interaction can be hydrophobic and confirm intercalation. Moreover, the complex induced detectable changes in the CD spectrum of CT-DNA. The fluorescence studies revealed that the probable quenching mechanism of fluorescence of the complex by CT-DNA is static quenching. The thermodynamic parameters (ΔH > 0 and ΔS > 0) showed that main interaction with hydrogenic forces occurred that is intercalation mode. Also, CV results confirm this mode because, with increasing the CT-DNA concentration, shift to higher potential was observed. [ABSTRACT FROM AUTHOR]

Guanidine supported on magnetic YSN P s MgFe 2 O 4 nanoparticles was created and estimated as a recoverable nanocatalyst for the synthesis of spirooxindole compounds in excellent yields. This nanocatalyst has two active base sites which one of them was Lewis base on the core such as nanoreactor and the other was organic functional base on the shell. • The Guanidine supported on magnetic YSNPs MgFe2O4 nanocatalyst was prepared via simple chemical process. • The catalyst was characterized using FT-IR, SEM, XRD, EDX, VSM, BET and TGA analyses. • The catalyst can be recovered six cycles without any loss of catalytic activity. • The YSNPs MgFe2O4@gunidine nanocatalyst was employed in synthesis of spirooxindole compounds. Guanidine supported on magnetic YSN P s MgFe 2 O 4 nanoparticles was created and estimated as a recoverable nanocatalyst for the synthesis of spirooxindole compounds in excellent yields. This nanocatalyst has two active base sites one of which them is Lewis base on the core such as nanoreactor and the other is organic base on the shell. This novel nanocatalyst was prepared and characterized by using FT-IR spectra, X-ray diffraction (XRD), TPD analysis, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermo gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and vibrating sample magnetometer (VSM). The catalyst can be recovered and recycled 6 times without marked loss of activity. [ABSTRACT FROM AUTHOR]