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This article deals with thermal postbuckling of sandwich beams caused by uniform temperature rise and resting on elastic foundations. The sandwich beam is composed of auxetic graphene-reinforced me...

Present investigation deals with the nonlinear vibration of a sandwich plate with a homogeneous core and graphene-reinforced composite (GRC) face sheets supported by an elastic foundation under thermal environmental conditions. The material properties of GRC face sheets are assumed to be piece-wise functionally graded by changing the volume fraction of graphene in the thickness direction. The material properties of both the homogeneous core and the GRC face sheets are assumed to be temperature-dependent, and are estimated by the extended Halpin-Tsai micromechanical model . Reddy’s higher order shear deformation plate theory and the von Karman-type kinematic nonlinearity are used to derive the motion equations which account for the plate-foundation interaction and the thermal effects. The nonlinear vibration solutions for the sandwich plate can be obtained by using a two-step perturbation technique . The effects of distribution type of reinforcements, core-to-face sheet thickness ratio , temperature variation, foundation stiffness and in-plane boundary conditions on the nonlinear vibration characteristics of sandwich plates with piece-wise functionally graded GRC face sheets are discussed in detail.

The present work focuses on vibration characteristics of damaged laminated composite plates. Damage is considered as a local reduction of anisotropic plate stiffness, and three damage factors (representing the damage severity, damage anisotropy, and damage location/area, respectively) are defined to describe damage status in the laminated composite plates. The analytical solutions are obtained by the perturbation method. A numerical analysis is conducted on the vibration of damaged laminated composited plates, and the effect of damage factors on the vibration characteristics is discussed. Results indicate that three damage factors have different influences on the vibration characteristics. Also, the modal curvatures and strain energy show higher damage sensitivity than the natural frequencies and displacement mode shapes. The perturbation-based vibration analysis developed in this study can be used to effectively evaluate the effect of damage on the vibration behavior of anisotropic plates and potentially identify the damage in the laminated plates.

This paper deals with the large amplitude vibration, nonlinear bending and thermal postbuckling of functionally graded material (FGM) beams resting on an elastic foundation in thermal environments. Two kinds of micromechanics models, namely, Voigt model and Mori-Tanaka model, are considered. The motion equations are based on a higher order shear deformation beam theory that includes beam–foundation interaction. The thermal effects are also included and the material properties of FGMs are assumed to be temperature-dependent. The numerical illustrations concern the nonlinear vibration, nonlinear bending and thermal postbuckling of FGM beams resting on Pasternak elastic foundations under different thermal environmental conditions. It is found that the FGM beam with intermediate material properties does not necessarily have intermediate nonlinear frequencies. The thermal postbuckling path of simply supported FGM beams is no longer of the bifurcation type for both uniform and non-uniform temperature fields.

A nonlinear analysis is presented for impact response of carbon nanotube-reinforced composite (CNTRC) structures under thermal conditions. Two plate configurations (i.e., single-layer and sandwich plates) are considered, and the nanotube reinforcement is either uniformly-distributed or functionally-graded in the plate thickness direction. The material properties of nanotube reinforced composites are estimated using micromechanical models. The equations of motion are based on a higher-order shear deformation theory with a von Karman-type of kinematic nonlinearity, and the thermal effects are included by considering the nanotube reinforced composites as temperature-dependent. The equations of motion are solved with a two-step perturbation technique, and the initial stresses caused by either the thermal or in-plane edge loads as in-plane boundary conditions are introduced. The influences of material property gradient, volume fraction distribution, temperature change, initial stress, initial velocity of the impactor, and core-to-face sheet thickness ratio on impact response of plate structures are discussed. The analysis presented can help better understand the nonlinear impact response of functionally-graded materials and facilitate design and optimization of nanocomposite structures against impact and under thermal and other environments.

This paper presents an investigation on the nonlinear dynamic response of sandwich plates with FGM face sheets resting on elastic foundations in thermal environments. The material properties of FGM layer are assumed to be graded in the thickness direction according to the Mori–Tanaka scheme. The governing equations of the plate that includes plate–foundation interaction are solved by a two-step perturbation technique. The thermal effects are also included and the material properties of both FGM face sheets and homogeneous core layer are assumed to be temperature-dependent. Two cases of the in-plane boundary conditions are considered. Initial stresses caused by thermal loads or in-plane edge loads are introduced. The numerical illustrations concern the nonlinear dynamic response of sandwich plates resting on Pasternak elastic foundations under different sets of thermal environmental conditions, from which results for single-layer FGM plates are also obtained for comparison purposes. The numerical results show that foundation stiffness and initial stress have a significant effect on the dynamic response of both single-layer and sandwich FGM plates. They also show that the core-to-face sheet thickness ratio has a significant effect on the dynamic response of sandwich FGM plates. The results reveal that the volume fraction distribution of FGM layer has a significant effect on the dynamic response of single-layer FGM plates, whereas this effect is less pronounced for the sandwich plate with FGM face sheets.

This paper deals with large amplitude vibration of hybrid laminated plates containing piezoelectric layers resting on an elastic foundation in thermal environments. The motion equation of the plate that includes plate-foundation interaction is based on a higher order shear deformation plate theory and solved by a two-step perturbation technique. The thermo-piezoelectric effects are also included and the material properties of both orthotropic layers and piezoelectric layers are assumed to be temperature-dependent. The numerical illustrations concern nonlinear vibration characteristics of unsymmetric cross-ply and antisymmetric angle-ply laminated plates with fully covered or embedded piezoelectric actuators under different sets of thermal and electrical loading conditions. The results show that the foundation stiffness and stacking sequence have a significant effect on the nonlinear vibration characteristics of the hybrid laminated plate. The results also reveal that the temperature rise reduces the natural frequency, but it only has a small effect on the nonlinear to linear frequency ratios of the hybrid laminated plate. The results confirm that the effect of the applied voltage on the natural frequency and the nonlinear to linear frequency ratios of the hybrid laminated plate is marginal except the plate is sufficiently thin.

A novel tetra-substituted zinc phthalocyanine 4 [ZnPcNHCOCH2(PEG)5NH2] was synthesized from 4-nitrophthalonitrile by using a four-step procedure. The compound has been characterized by UV–Visible, fluorescence, IR, 1H NMR spectra and MALDI-TOF MS, and the satisfactory result has been obtained. Most importantly, this compound is soluble in many solvents including CHCl3, CH2Cl2, DMF, DMSO, THF and water.

This paper presents an investigation on the nonlinear dynamic response of carbon nanotube-reinforced composite (CNTRC) plates resting on elastic foundations in thermal environments. Two configurations, i.e., single-layer CNTRC plate and three-layer plate that is composed of a homogeneous core layer and two CNTRC surface sheets, are considered. The single-walled carbon nanotube (SWCNT) reinforcement is either uniformly distributed (UD) or functionally graded (FG) in the thickness direction. The material properties of FG-CNTRC plates are assumed to be graded in the thickness direction, and are estimated through a micromechanical model. The motion equations are based on a higher-order shear deformation theory with a von Karman-type of kinematic nonlinearity. The thermal effects are also included and the material properties of CNTRCs are assumed to be temperature-dependent. The equations of motion that includes plate-foundation interaction are solved by a two-step perturbation technique. Two cases of the in-plane boundary conditions are considered. Initial stresses caused by thermal loads or in-plane edge loads are introduced. The effects of material property gradient, the volume fraction distribution, the foundation stiffness, the temperature change, the initial stress, and the core-to-face sheet thickness ratio on the dynamic response of CNTRC plates are discussed in detail through a parametric study.

This paper studied the large amplitude vibration and the nonlinear bending of a sandwich plate with carbon nanotube-reinforced composite (CNTRC) face sheets resting on an elastic foundation in thermal environments. The material properties of CNTRC face sheets are assumed to be graded in the thickness direction, and are estimated through a micromechanical model. The governing equation of the plate that includes plate-foundation interaction is solved by a two-step perturbation technique. The thermal effects are also included and the material properties of both CNTRC face sheets and homogeneous core layer are assumed to be temperature-dependent. A detailed parametric study is conducted to study the effects of nanotube volume fraction, core-to-face sheet thickness ratio, temperature change, foundation stiffness and in-plane boundary conditions on the nonlinear vibration characteristics and nonlinear bending behaviors of sandwich plates with functionally graded CNTRC face sheets. The results for the same plate with uniformly distributed CNTRC face sheets are also provided for comparison.

Nonlinear vibration, nonlinear bending and postbuckling analyses are presented for a sandwich plate with FGM face sheets resting on an elastic foundation in thermal environments. The material properties of FGM face sheets are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The governing equation of the plate that includes plate-foundation interaction is solved by a two-step perturbation technique. The thermal effects are also included and the material properties of both FGM face sheets and homogeneous core layer are assumed to be temperature-dependent. The numerical results reveal that the foundation stiffness and temperature rise have a significant effect on the natural frequency, buckling load, postbuckling and nonlinear bending behaviors of sandwich plates. The results also reveal that the core-to-face sheet thickness ratio and the volume fraction distribution of FGM face sheets have a significant effect on the natural frequency, buckling load and postbuckling behavior of the sandwich plate, whereas this effect is less pronounced for the nonlinear bending, and is marginal for the nonlinear to linear frequency ratios of the same sandwich plate.

This paper deals with the large amplitude vibration of nanocomposite plates reinforced by single-walled carbon nanotubes (SWCNTs) resting on an elastic foundation in thermal environments. The SWCNTs are assumed aligned, straight and a uniform layout. Two kinds of carbon nanotube-reinforced composite (CNTRC) plates, namely, uniformly distributed (UD) and functionally graded (FG) reinforcements, are considered. The material properties of FG-CNTRC plates are assumed to be graded in the thickness direction, and are estimated through a micromechanical model. The motion equations are based on a higher-order shear deformation plate theory that includes plate-foundation interaction. The thermal effects are also included and the material properties of CNTRCs are assumed to be temperature-dependent. The equations of motion are solved by an improved perturbation technique to determine nonlinear frequencies of CNTRC plates. Numerical results reveal that the natural frequencies as well as the nonlinear to linear frequency ratios are increased by increasing the CNT volume fraction. The results also show that the natural frequencies are reduced but the nonlinear to linear frequency ratios are increased by increasing the temperature rise or by decreasing the foundation stiffness. The results confirm that a functionally graded reinforcement has a significant effect on the nonlinear vibration characteristics of CNTRC plates.

During the last decade, gold nanoparticles (AuNPs)-based assays have been well developed and widely used in biological analysis and biomedical detections because AuNPs have unique physical and chemical properties, which are extremely sensitive to environmental conditions (e.g., size, shape, ligand, and degree of aggregation). In particular, the AuNPs-based assays have already been used for detecting practical samples with high simplicity and selectivity. This review discusses the recent development of the synthesis and biological molecular functionalization of AuNPs and their applications on cellular analysis and detections of the heavy metallic cations, small organic compounds, nucleic acids, and proteins.

We present a newly designed colorimetric sensor sensitive to pH value based on a gold nanocomposite composed of gold nanoparticles and pH-sensitive polymer{dodecylthioether end functionalized poly[2-(diethylamino) ethyl methacrylate], poly(DEAEMA)-DDT}. We have shown that this design can produce stable GNP precipitate under weakly basic condition(pH=7.5) and this precipitate can be dispersed in acidic solution(pH=4.0), due to the 2-(diethylamino) ethyl methacrylate protonated by H+. The precipitation-dispersion process is reversible and accompanied by distinct color change that are clearly visible to the naked eye. This development may have application in the controlled fabrication of reversible pH-sensitive nanostructures and/or devices.

Fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography imaging can be used to assess the treatment efficacy of chemotherapy and prognosis. The aim of this study was to determine the uptake rate of (18)F-FDG in colon cancer HCT-116 cells, and to evaluate the treatment efficacy of chemotherapy, hyperthermia and thermo-chemotherapy through the uptake inhibition rate of (18)F-FDG.The uptake rate of (18)F-FDG in HCT-116 cells was determined at various experimental conditions. The inhibition rate of cell growth, uptake rate of (18)F-FDG and uptake inhibition rate of (18)F-FDG in HCT-116 cells treated with 5-fluorouracil (5-FU) at various concentrations were determined. In HCT-116 cells subjected to chemotherapy (5-FU, 100 µg/ml), hyperthermia (43°C, 40 minutes) and thermo-chemotherapy for 24 hours, the inhibition rate of cell growth and uptake inhibition rate of (18)F-FDG were determined; early apoptosis, the morphology and ultrastructure of HCT-116 cells were examined; and the contents of glucose and lactate dehydrogenase (LDH) in the cell culture medium of HCT-116 cells were determined. One-way analysis of variance (ANOVA) and correlation analyses were conducted by using SPSS 16.0 software.The uptake rate of (18)F-FDG in HCT-116 cells was (44.25 ± 2.19)%. Under the condition of adding 5-FU at various concentrations for 24 hours, the uptake rate of (18)F-FDG was negatively correlated with 5-FU dosage (r = -0.879, P0.01); the inhibition rate of cell growth revealed a positive correlation with the uptake inhibition rate of (18)F-FDG (r = 0.831, P0.01). In HCT-116 cells subjected to hyperthermia, chemotherapy, and thermo-chemotherapy for 24 hours, the uptake inhibition rates of (18)F-FDG were (12.94 ± 2.80)%, (28.25 ± 4.59)%, and (21.60 ± 3.68)%, respectively. The early apoptotic rates of HCT-116 cells were (9.80 ± 0.16)%, (19.80 ± 2.40)%, and (15.70 ± 1.80)%, respectively. Moreover, the contents of glucose and LDH in cell culture medium of HCT-116 cells after treatments were higher than those before treatment.The uptake inhibition rate of (18)F-FDG can be used for early evaluation of hyperthermia and 5-FU treatment efficacy on cancer cells although hyperthermia (43°C, 40 minutes) does not reveal the synergistic effect on 5-FU at the low dosage.

To evaluate the clinic value of (18)F-FDG PET/CT imaging in differentiation of malignant from benign disease in lung.188 patients underwent (18)F-FDG 45 min early and 2 h delayed PET/CT imaging after intravenous injection of (18)F-FDG. The standardized uptake value (SUV) and retention index (RI) of region of interesting were calculated. The histological diagnosis or clinical findings in a 12 months follow-up period served as the standard of truth.In 114 patients with malignant disease and 74 patients with benign disease, the sensitivity, speciality and accuracy of (18)F-FDG PET/CT imaging in differentiation of malignant from benign lung nodules (diameter more than 10 mm) were 98.2%, 80.0%, and 96.6%, in mediastinal lymph nodes and were 95.7%, 41.7%, and 84.8%, respectively. The sensitivity of (18)F-FDG PET imaging for lung nodules (diameter less than 10 mm) was lower than CT.Integrated PET/CT imaging provides high sensitivity, specificity and reasonably high accuracy for lung cancer.

Application of controlled-release nitrogenous fertilizers can improve the efficiency of fertilizers and reduce the environmental pollution. Controlled-release urea (coated urea) is one of the controlled-release nitrogenous fertilizers developed quickly in the recent years. The rate of controlled-release urea pervasion through membrane is the most important index of the capacity of controlled release. There is a maximum absorption at lambda=426 nm with complex in acidic solution, using p-dimethylaminozenzaldehyde as color reagent, and the absorbance exhibits a linear reponses to the urea concentration over the range of 7.5-210 microg x mL(-1). The method for determining the rate of controlled-release urea pervasion through membrane was realized through determining the content of urea in the liquor, the recovery efficiency of the method is 96.1%-103.9%.