Search

This report presents an analytical approach to the natural frequency analysis of a porous beam consisting of a host porous layer reinforced with graphene platelets (GPLs), namely GPL-reinforced porous core, and two piezoelectric outer layers. In the modelling, symmetric distributions of both porosity and GPLs in the core are supposed. The effective mechanical properties of the GPL-reinforced porous core are estimated by Halpin–Tsai model and the rule of mixture. The electric potential in each piezoelectric layer is assumed to vary linearly across its thickness. Two types of electrical boundary conditions, which are open- and closed-circuits, are considered for the free surfaces of the piezoelectric layers. Parabolic shear deformation beam theory associated with Hamilton’s principle is adopted to derive the governing equations of the free vibration. Afterwards these equations are solved analytically by Navier’s solution. Comparative and comprehensive studies are carried out to examine the accuracy and effects of parameters and conditions, such as GPL weight fraction, porosity coefficient, and electrical boundary conditions on the natural frequencies of the beam.

This paper aims to present thermo-electrical free vibration characteristics of functionally graded material (FGM) sandwich beam placed on the two-parameter elastic foundation. The beam is constructed of a foam core, two middle FGM layers, and two outer piezoelectric layers. It is assumed that the beam is subjected to a constant voltage and a uniform/linear temperature distribution. Physical properties of the core and two middle layers vary smoothly through the thickness according to the cosine and power-law forms, respectively. Lagrange equations in conjunction with the Reddy third-order beam theory is employed to derive the governing equations of motion. A simple polynomial trial function-based Ritz method is adopted for the approximation of the displacement field to obtain the vibration response. The correctness of the study is verified by comparisons with other authors’ published results. Influences of geometry parameters, material property distribution, applied voltage, elastic foundation, temperature distribution, temperature change, porosity coefficient, span-to-height ratio, and boundary conditions are investigated through parametric studies.

A point interpolation meshfree method based on polynomial basic function is employed to analyze static behavior of sandwich beams with functionally graded face sheets and porous core whose mechanical properties vary continuously in the depth-direction. Transverse shear deformation is taken into account with the context of third-order beam theory which satisfies the vanishing of shear stress at the top and bottom surfaces. The equilibrium equations are derived from the principle of virtual work. Polynomial basic function is employed to construct shape functions and approximate the displacement field of computational domain. The accuracy of the computational method is confirmed by comparisons of computed results with those available in the literature. The convergence rate and effect of nodal distribution on the accuracy are examined in details. Numerical examples are performed to investigate the effects of span-to-height ratio, face sheet-core-face sheet thickness ratio, material volume fraction index, porosity coefficient, as well as different boundary conditions on transverse displacement, axial and shear stresses of the beams.

The methanol oxidation reaction (MOR) has recently gained a lot of attention due to its application in fuel cells and electrochemical sensors. To enhance the MOR, noble metal nanoparticles should be homogeneously dispersed on the electrode surface with the aid of one suitable support. In this work, 4-aminothiophenol (4-ATP) molecules which contain simultaneously amine and thiol groups were electro-grafted onto the electrode surface to provide anchoring sites, limit aggregation and ensure good dispersion of metal nanoparticles. The results showed a high density of platinum nanoparticles (PtNPs) with an average size of 25 nm on the glassy electrode modified with a 4-ATP supporting layer. Consequently, the MOR was improved by 2.1 times with the aid of the grafted 4-ATP layer. The electrochemical sensor based on PtNPs/4-ATP/GCE is able to detect MeOH in a linear range from 1.26 to 21.42 mM with a detection limit of 1.21 mM.

In 1953, Victor Thébault conjectured a link between the altitudes of a tetrahedron and the radical center of the four spheres with the centers at the vertices of this tetrahedron and the corresponding tetrahedron altitudes as radii. This conjecture was proved in 2015. In this paper, we propose an analogue of Th\'{e}bault's theorem. We establish a link between the radical center of the four spheres, the insphere, and the Monge point of a tetrahedron.

Bis(3-indolyl)methanes (BIM) are highly valuable and appear in the core structure of many natural products and pharmacologically active compounds (anticancer, anti-inflammatory, antiobesity, antimetastatic, antimicrobial, etc.). Herein, we have disclosed an air stable and highly efficient CuFe2O4 heterogeneous catalyst for alkylation of indoles with alcohols to give bis(3-indolyl)methanes in very good yields. The CuFe2O4 catalyst has been found to be magnetically recycled at least five times without losing significant catalytic activity.

Here we report a new ceasium Brønsted ion-exchanged Al-SBA-15 (Cs/AS15) supported heteropoly acid (HPA) H3PW12O40 (HPA-Cs/AS15) material which can be prepared and used as heterogeneous catalyst for the fructone fragrancy synthesis. It was demonstrated that Cs+ was more effective than NH4+ as counter cation of ion-exchanged AS15 support for preparing HPA/AS15 catalyst with higher acidity and HPA leaching stability. HPA-Cs/AS15 material showed high acidity with the maximum NH3 desorption peak appeared at 759.6 °C in the NH3-TPD spectrum, stronger than pure HPA (635.7 °C) and the ammonium Brønsted ion-exchanged Al-SBA-15 supported HPA (HPA-NH4/AS15) (559.1 °C) materials. The HPA leaching stability test showed that the HPA content of HPA-Cs/AS15 catalyst reduced only by 2.55% after five washing times, much less than that of HPA-NH4/AS15 catalyst (49.22%).The higher acidity helped improve the HPA-Cs/AS15 catalyst performance in the fructone fragrancy synthesis. The ethyl acetoacetate conversion over this catalyst was 94.82%, better than those over HPA-NH4/AS15 (93.49%) and pure HPA (89.52%) catalysts, although HPA-Cs/AS15 catalyst had lower HPA content (23.16 wt%) than HPA-NH4/AS15 (24.28 wt%). In addition, it was shown that the reaction conditions such as ethyl acetoacetate:ethanediol reactant molar ratio of 1:1.5, ethanediol used as the diol reactant, and toluene used as the solvent, the fructone fragrancy synthesis reaction over HPA-Cs/AS15 catalyst reached the highest ethyl acetoacetate conversion (95.58%). The toluene’s boiling temperature of 110.6 °C can promote the dispersion and contact abilities of the reactants with HPA molecules presented inside the pores of HPA-Cs/AS15 catalyst.

Background The majority of infectious diseases of cultured fish is caused by bacteria. Rapid identification of bacterial pathogens is necessary for immediate management. The present study developed a custom Main Spectra Profile (MSP) database and validate the method using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for rapid identification of fish bacterial pathogens. Streptococcus agalactiae, Streptococcus iniae, Aeromonas hydrophila, Aeromonas veronii, and Edwardsiella tarda obtained from diseased fish were used as representative bacterial pathogens in this study. Bacterial peptides were extracted to create a Main Spectra Profile (MSP), and the MSPs of each bacterial species was added into the MALDI Biotyper database. Fifteen additional isolates of each bacterial species were tested to validate the utilized technique. Results The MSPs of all field isolates were clearly distinguishable, and the MSPs of the same species were clustered together. The identification methodology was validated with 75 bacterial isolates. The reliability and specificity of the method were determined with MALDI Biotyper log score values and matching results with 16 s rDNA sequencing. The species identification using the public MALDI Biotyper library (Bruker MALDI Biotyper) showed unreliable results (log score 2.115, and a 100% matching result. Conclusion This study demonstrates an effective identification of fish bacterial pathogens when a complete custom-made MSP database is applied. Further applications require a broad, well-established database to accommodate prudent identification of many fish bacterial pathogens by MALDI-TOF MS.

Accepted manuscript version, licensed CC BY-NC-ND 4.0. An eight-week experiment was performed to assess the effectiveness of watermelon rind powder (WMRP) on growth efficiency, immunity, and disease resistance of Nile tilapia, O. niloticus. Three hundred fish (17.14 ± 0.12 g) were fed five diets; 0 (Diet 1- control), 20 g kg−1 WMRP (Diet 2), 40 g kg−1 WMRP (Diet 3), 80 g kg−1 WMRP (Diet 4), and 160 g kg−1 WMRP (Diet 5). Growth parameters, skin mucus, and serum immunities were analyzed after four and eight weeks of feeding. After eight weeks of the feeding, ten fish were used in the challenge against Streptococcus agalactiae over 15 days. Statistically significant enhancement (P ≤ .05) of skin mucus and serum immune parameters were revealed through the WMRP feeding vs. control fed fish, in which the maximum (P ≤ .05) enhancement of immune parameters was detected in tilapia fed the 40 g kg−1 WMRP diet, followed by the 20, 80, and 160 g kg−1 WMRP diets. Relative percent survival (RSP) in the challenge study of fish fed 20, 40, 80, and 160 g kg−1 WMRP was 57.14%, 76.19%, 61.90%, and 52.38%, respectively. The growth parameters were statistically (P ≤ .05) enhanced in the WMRP feedings, in which the largest increase was revealed in the 40 g kg−1 WMRP treatment. In summary, the 40 g kg−1 WMRP additive increased both the growth efficiency and health status of Nile tilapia.

Around the world, the data assimilation framework has been reported to be of great interest for weather forecasting, oceanography modeling and for shallow water flows particularly for flood model. For flood model this method is a power full tool to identify time-independent parameters (e.g. Manning coefficients and initial conditions) and time-dependent parameters (e.g. inflow). This paper demonstrates the efficiency of the method to identify time-dependent parameter: inflow discharge with a real complex case Red River. Firstly, we briefly discuss about current methods for determining flow rate which encompasses the new technologies, then present the ability to recover flow rate of this method. For the case of very long time series, a temporal strategy with time overlapping is suggested to decrease the amount of memory required. In addition, some different aspects of data assimilation are covered from this case.

A miniaturised array of supercritical angle fluorescence (SAF) micro-optics embedded in a microfluidic chamber was fabricated by injection moulding. The fabricated chip could enhance the fluorescence signal around 46 times compared to a conventional microscope. Collection of the fluorescence signal from the SAF array is almost independent of the numerical aperture, and the limit of detection was improved 36-fold using a simple and inexpensive optical detection system.

In this article, a significant aspect of Brønsted groups in the preparation of HPA/Al-SBA-15 catalyst by immobilising heteropoly acid H3PW12O40 (HPA) to mesoporous Al-SBA-15 support was studied. The crucial factors affected the preparation such as functional groups formed on the support, the use of HPA type for the immobilisation (commercial catalyst or in-situ synthetic HPA), and Si/Al molar ratio of Al-SBA-15 were systematically investigated. The prepared catalysts were tested their performance in polar reagent reactions (fructone synthesis was chosen as an example) to show the effect of HPA after the immobilisaton. Here we tested the HPA content (by Energy-dispersive X-ray method), acidity (by temperature-programmed desorption of ammonia method) and the ethyl acetoacetate conversion in fructone synthesis to prove this concept. The other characterisation methods such as small angle x-ray scattering, Fourier-transform infrared spectroscopy, specific surface area and pore volume also showed the properties change of materials before and after HPA immobilisation. It was shown that the HPA/Al-SBA-15 sample prepared by using HPA commercial catalyst and NH4 + ion-exchanged Brønsted groups of mesoporous Al-SBA-15 support (Si/Al molar ratio of 15) showed the highest acidity and catalytic activity (ethyl acetoacetate conversion of 93.49 wt%) in comparison to HPA commercial catalyst as well as to the other catalysts. In addition, this catalyst also showed good catalytic stability after five reaction cycles with slightly reduction of activity, suggesting the prospect of employing HPA/Al-SBA-15 catalyst for organic synthesis of polar compounds.

Solid-phase PCR (SP-PCR) has attracted considerable interest in different research fields since it allows parallel DNA amplification on the surface of a solid substrate. However, the applications of SP-PCR have been hampered by the low efficiency of the solid-phase amplification. In order to increase the yield of the solid-phase amplification, we studied various parameters including the length, the density, as well as the annealing position of the solid support primer. A dramatic increase in the signal-to-noise (S/N) ratio was observed when increasing the length of solid support primers from 45 to 80 bp. The density of the primer on the surface was found to be important for the S/N ratio of the SP-PCR, and the optimal S/N was obtained with a density of 1.49 × 1011 molecules/mm2. In addition, the use of solid support primers with a short overhang at the 5' end would help improve the S/N ratio of the SP-PCR. With optimized conditions, SP-PCR can achieve amplification efficiency comparable to conventional PCR, with a limit of detection of 1.5 copies/μl (37.5 copies/reaction). These improvements will pave the way for wider applications of SP-PCR in various fields such as clinical diagnosis, high-throughput DNA sequencing, and single-nucleotide polymorphism analysis. Graphical abstract Schematic representation of solid-phase PCR.

Solid-phase PCR (SP-PCR) has become increasingly popular for molecular diagnosis and there have been a few attempts to incorporate SP-PCR into lab-on-a-chip (LOC) devices. However, their applicability for on-line diagnosis is hindered by the lack of sensitive and portable on-chip optical detection technology. In this paper, we addressed this challenge by combining the SP-PCR with super critical angle fluorescence (SAF) microlens array embedded in a microchip. We fabricated miniaturized SAF microlens array as part of a microfluidic chamber in thermoplastic material and performed multiplexed SP-PCR directly on top of the SAF microlens array. Attribute to the high fluorescence collection efficiency of the SAF microlens array, the SP-PCR assay on the LOC platform demonstrated a high sensitivity of 1.6 copies/µL, comparable to off-chip detection using conventional laser scanner. The combination of SP-PCR and SAF microlens array allows for on-chip highly sensitive and multiplexed pathogen detection with low-cost and compact optical components. The LOC platform would be widely used as a high-throughput biosensor to analyze food, clinical and environmental samples.

Objective To investigate the antitumor effect of maesopsin 4-O-β-glucoside (TAT2) isolated from the leaves of Artocarpus tonkinensis (A. tonkinensis) A. Chev. ex Gagnep. Methods The antitumor activity of TAT2 was evaluated in Lewis lung carcinoma (LLC) tumor-bearing mice. BALB/c mice had tumors induced by implantation with 2 × 106 LLC cells into the subcutaneous right posterior flank. Tumor-bearing mice were treated orally with a range of doses of TAT2 and a standard drug, doxorubicin. Animals were observed for tumor growth and mortality rate. Blood was collected to determine hematological and biochemical parameters. Results TAT2 was isolated from an ethanolic extract of A. tonkinensis leaves. Its structure was determined by MS and NMR spectroscopy, and identified as TAT2. The compound did not show acute toxicity at the highest dose tested (2 000 mg/kg body weight). TAT2 exhibited antitumor activity by decreasing tumor growth, increasing the survival rate, and ameliorating some hematological and biochemical parameters at doses of 100 and 200 mg/kg body weight (P Conclusions These results indicate that TAT2 possesses clear antitumor activity. Due to its bioavailability and low toxicity, and the fact that it could be isolated in a large scale from A. tonkinensis leaves, the compound shows promise as a potential anticancer drug.

We have investigated a surfactant-assisted sonochemical approach to produce monodisperse Fe₃O₄ nanoparticles (NPs). The non-ionic surfactant Igepal CO-520 (Poly(oxyethylene)(5) nonylphenyl ether) has been used for the preparation of NPs and the effects on the NP size, size distribution, and magnetic properties have been studied. The Fe₃O₄ NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The results reveal that the NPs prepared by a Igepal CO-520-assisted sonochemical method exhibit a narrow range of size distributions and a high monodispersity compared to the NPs from the conventional sonochemical method. The analysis of NPs prepared in the presence of the surfactant suggested that it could be used not only as a protector to prevent the oxidation of Fe (Ⅱ), but also as a controller to vary the size of the NPs.

We have investigated the planar Hall effect (PHE) in three multilayer structures such as a bilayer, a spin-valve and a weak exchange bias coupling bilayer structure introduced a very thin Cu spacer layer between the antiferromagnetic and ferromagnetic layers. These thin films are Ta(3)/NiFe(10)/IrMn(10)/Ta(3) (nm), Ta(3)/NiFe(10)/Cu(1.2)/NiFe(2)/IrMn(10)/Ta(3) (nm), and Ta(3)/NiFe(10)/Cu(0.2)/IrMn(10)/Ta(3) (nm), respectively. The active layers in all three structures were kept constant. The field-sensitivity of the fabricated PHE sensors obtained for the respected structures are about 1.6 muV middot Oe-1, 5 muV middot Oe-1, and 12 muV middot Oe-1, respectively. The results suggest that the sensor based on a weak exchange bias coupling structure has the highest field-sensitivity compared with the others. The proposed weak exchange bias coupling structure emphasizes for the development of the PHE sensor materials.

Planar Hall effect (PHE) sensors with the junction size of 50 mum times 50 mum were fabricated successfully by using spin-valve thin films Ta(5)/NiFe(x) /Cu(1.2)/NiFe(2)/IrMn(15)/Ta(5) (nm) with x = 4, 8, 10, 12, 16. The magnetic field sensitivity of the PHE sensors increases with increasing thickness of ferromagnetic (FM) free layer. The sensitivity of about 95.5 m Omega/(kA/m) can be obtained when the thickness of the FM-free layer increases up to 16 nm. The enhancement of sensitivity is explained by the shunt current from other layers. The PHE profiles are well described in terms of the Stoner-Wohlfarth energy model. The detection of magnetic micro-beads label Dynabeadsreg M-280 is demonstrated and the results revealed that the sensor is feasible for high-resolution biosensor applications.

This paper deals with the planar Hall effect (PHE) of Ta(5)/NiFe(tF)/Cu(1.2)/NiFe(tP)/IrMn(15)/Ta(5) (nm) spin-valve structures. Experimental investigations are performed for 50 mumtimes50 mum junctions with various thicknesses of free layer (tF = 4, 8, 10, 12, 16, 26 nm) and pinned layer (tP = 1, 2, 6, 8, 9, 12 nm). The results show that the thicker free layers, the higher PHE signal is observed. In addition, the thicker pinned layers lower PHE signal. The highest PHE sensitivity S of 196 muV/(kA/m) is obtained in the spin-valve configuration with tF = 26 nm and tP = 1 nm. The results are discussed in terms of the spin twist as well as to the coherent rotation of the magnetization in the individual ferromagnetic layers. This optimization is rather promising for the spintronic biochip developments.

Foodborne disease is a major public health threat worldwide. Salmonellosis, an infectious disease caused by Salmonella spp., is one of the most common foodborne diseases. Isolation and identification of Salmonella by conventional bacterial culture or molecular-based methods are time consuming andusually take a few hours to days to complete. In response to the demand for rapid on line or at site detection of pathogens, in this study, we describe for the first time an eight-chamber lab-on-a-chip (LOC) system with integrated magnetic beads-based sample preparation and loop-mediated isothermalamplification (LAMP) for rapid and quantitative detection of Salmonella spp. in food samples. The whole diagnostic procedures including DNA isolation, isothermal amplification, and real-time detection were accomplished in a single chamber. Up to eight samples could be handled simultaneously and the system was capable to detect Salmonella at concentration of 50 cells per test within 40 min. The simple design, together with high level of integration, isothermal amplification, and quantitative analysis of multiple samples in short time will greatly enhance the practical applicability of the LOC system for rapid on-site screening of Salmonella for applications in food safety control, environmental surveillance, and clinical diagnostics.

The AlCrN films were grown by RF reactive sputtering method under the selected conditions. The Cr concentration was varied by the number of Cr pieces placed on the Al target. The sample quality has been studied by XRD, Auger spectroscopy, optical absorption and electrical resistant measurements. The XRD and Auger results show that the samples consist of a major phase with the Al 1-x CrxN formula, which has a hexagonal structure, and a few percents at. of oxygen, which may form Al₂O₃. There exist the Cr clusters in the samples with high concentration of Cr. The optical absorption measurement provides the information about the band gap that relates strongly to the quality of samples. The quality of samples is also clearly reflected in electrical measurement, i.e., the temperature dependence of resistance exhibits a semiconductor characteristic only for the samples that have no Cr cluster. In these cases, the values of ionization energies Ea can be derived from R(T) plots by using the function R(T) = Ro exp (Ea/k B T).

International audience; The field sensitivity of a planar Hall effect (PHE) micro-ring type biosensor has been investigated as a function of magnetizing angle of the sensor material, for the sensing of low magnetic moment superparamagnetic labels. The field sensitivity is maximal at a magnetizing angle of α = 20°. At this optimized magnetizing angle, the field sensitivity of a PHE sensor is about 3.6 times higher than that measured at the conventional configuration, α = 90°. This optimization enables the PHE-ring sensor to detect superparamagnetic biolabels with ultra-low magnetic moments down to 4 × 10-13 emu.

A new dimeric pyranocarbazole alkaloid, bisisomahanine (1), was isolated from the roots of Glycosmis stenocarpa (DRAKE) TAN., along with two known monomeric carbazole alkaloids, murrayafoline-A (2) and murrayanine (3). The planar structure of bisisomahanine was determined to be 9,9''-dihydroxy-3,3'',8,8''-tetramethyl-3,3''-bis-(4-methyl-3-pentenyl)-3,3'',11,11''-tetrahydro-10,10''-(bipyrano[3,2-a]carbazole) from the combination of spectroscopic and chemical evidence. Bisisomahanine is the first dimeric prenylated pyranocarbazole alkaloid with a 1,1' type of linkage; the NMR and CD spectroscopic data indicated it to be a mixture of diastereomers having a dominant configuration at the axis of chirality. (1)H- and (13)C-NMR assignments of murrayafoline-A were made on the basis of 2D-experiments.