Search

The dynamic response of a 5 MW floating wind turbine is examined using the coupled finite element simulations, and the dynamic effects of the catenary is considered, while the coupling between flex...

With the development of deep-sea oil and gas resources, the aspect ratio of deep-sea flexible riser has reached the order of 102–103, which makes the experimental model of the equal scale of deep-sea flexible risers challenging to achieve under typical experimental conditions. Alternatively, the non-scale experiment is sometimes used. However, the dynamic response of the prototype may not be exactly modeled. To solve the problem, this paper expands the distortion similarity method to consider the pretension and designs a distortion model of the deep-sea flexible riser based on the improved distortion similarity method. Applying the governing equation and dimensional analysis method to analyze the prototype and experimental model, the design method of the distortion model is obtained. In the numerical analysis, the design of the distortion model of a top tensioned riser (TTR) is carried out, and the selection criteria and range of the aspect ratio are proposed. The three parts of the natural frequency similarity, the pretension non-satisfaction similarity, and the error analysis are studied. This analytical study indicates that the transverse direction of the distortion model satisfies the similarity of the dynamics, and the longitudinal direction satisfies the static similarity. The selection of the aspect ratio of the distortion model should satisfy three factors.

Herein, we present a new strategy that for the first time achieved chemo- and enantio-selective hydrogenation of alkenes over arylhalides. Key to the success is that instead of using external poisons, we use the composition of the bimetallic nanocrystal catalysts to control chemoselectivity (hydrogenation of C=C bonds without cleavage of Ar-X bonds). We further show that this system combined with surface modifying chiral ligands can control the enantioselectivity. Thus, after synthesizing and screening a series of easily accessible MxAuy (M = Pd, Pt; x, y = 1, 3, 5) bimetallic nanocrystals (9-10 nm) supported on activated carbon, we identified that Pt1Au1/C is a recyclable and generally applicable catalyst for the chemoselective hydrogenation of alkenes without cleaving aryl halogen bonds. Furthermore, cinchonidine modified Pt1Au1/C is shown to be capable of enantioselective hydrogenation, as illustrated by the rapid and enantio-enriched synthesis of RIP1 inhibitor analogue 7-Br-O-Nec1.

Flexible structures are common in nature and engineering. Under the action of fluid, the flexible structure bends to reduce drag. The study of this phenomenon has important scientific and engineering significance, so this article conducts research. Firstly, the differential equations are established, then solved by numerical methods, and finally numerically simulated.

Deep-sea minerals such as polymetallic nodule, hydrothermal sulphides and ferro-manganese crusts have for long attracted attention as an alternative source of metals to terrestrial deposits. To bring these minerals up to the land, flexible risers are needed. As the mining industry developing towards deep sea area, the conveying system is usually designed as a combination of steel riser and flexible riser. According to different transport requirements, various flexible riser configurations, such as steel catenary riser, lazy-wave riser and saddle-shaped riser, have been proposed. During mining operation, the riser bears gravity, buoyancy, wave and current force, therefore the assessment of structural safety and reliability is quite challenging. In addition, the riser response caused by the mining vehicle motion during working process in a large area should also be considered. To guarantee a safe operation and service life of the riser, it is necessary to carefully design its configuration and to analyze its performance. In this study, taking the saddle-shaped riser as our model, the influences of main design parameters on the riser configuration, tension and stress are examined. These parameters include the installation position of buoyancy modules, the buoyancy ratio and motion of mining vehicle. Firstly, the analysis model of the riser response is established based on FEM in which the nonlinear large displacement and deformation of the structure are considered. Secondly, through our FEM simulation, the distribution and variation of tension and stress along the axial length of risers with different configurations are presented. Finally, the impacts of the mining vehicle motion on riser response are discussed. Our numerical results show that a small change of the buoyancy position and buoyancy ratio may lead to a significant change of the riser configuration, but a little change of riser tension/stress. And the saddle-shaped riser has a good tolerance performance to the bottom-end excitation.

Multi-frequency vortex-induced vibration of flexible riser in lineally sheared fluid fields with different shearing parameters is explored by using the numerical approach. By combining the finite element method with a hydrodynamic model, the approach can consider mode competition based on modal energy and can carry out nonlinearly simultaneously dynamic response in time domain. Our analysis shows that multi-frequency VIV may occur both in non-uniform and uniform fluid fields. And, the behaviors of multi-frequency VIV are different from single-frequency VIV. Because several modes are involved and compete with each other, and consequently the determination of modal excitation region become more complicated. As the towing speed (or the shearing parameter) increases in sheared flow, the average RMS displacement does not regularly rise (or drop), but slightly fluctuates owing to changes of the participating mode and its excitation region. On the other hand, the average RMS stress gradually rises owing to higher-order modes being included. Moreover, it is found that the dominant frequency distributing along structural span significantly changes with the towing speed, and the length of the first dominant frequency gets smaller due to larger shearing parameter along with more intense competition between the participating modes.

Si–H bond activation is an important process implicated in many useful synthetic applications including silylation and transfer hydrogenation reactions. Herein we discovered homolytic activation of Si–H bonds on the surface of nanoporous gold (NPG), forming hydrogen radicals and [Au]–[Si] intermediates. By virtue of this new reactivity, we achieved highly selective mono and sequential alcoholysis of dihydrosilane. In addition, the amphiphilic nature of the [Au]–[Si] intermediate allows for a new bis-silylation reaction of cyclic ethers. The present work showcased that the surface reactivity of nanocatalysts may provide exciting opportunity for new reaction discovery.

Under the actions of ocean currents and/or waves, deep-sea flexible risers are often subject to vortex-induced vibration (VIV). The VIV can lead to severe fatigue and structural safety issues caused by oscillatory periodic stress and large-amplitude displacement. As flexible risers have natural modes with lower frequency and higher density, a multimode VIV is likely to occur in risers under the action of ocean currents, which is considered as shear flow. To decrease the response level of the VIV of the riser actively, a multimode control approach that uses a bending moment at the top end of the riser via an LQR optimal controller is developed in this study. The dynamic equations of a flexible riser including the control bending moment in shear flow are established both in the time and state-space domains. The LQR controllers are then designed to optimize the objective function, which indicates the minimum cost of the riser's VIV response and control input energy based on the Riccati equation of the closed-loop system under the assumption that the lift coefficient distribution is constant. Finally, the VIV responses of both the original and closed-loop systems under different flow velocities are examined through numerical simulations. The results demonstrate that the designed active control approaches can effectively reduce the riser displacement/angle by approximately 71%–89% compared with that of the original system. Further, for multimode control, the presented mode-weighted control is more effective than the mode-averaged control; the decrease in displacement is approximately 1.13 times than that of the mode-averaged control. Owing to the increase in flow velocity as more and higher-order modes are excited, the VIV response of the original system decreases slightly while the frequency response gradually increases. For the closed-loop system, the response becomes smaller and more complicated, and the efficiency of the controller becomes lower at a certain flow velocity.

The aerobic oxidation of diaryl and aryl(hetero) methylenes into ketones, catalyzed by Ag/C nanoparticles under mild conditions, was successfully developed. This method features a wide scope of substrates, good yields, and uncomplicated recycling of the catalyst.

Catenary is increasingly used as mooring-line and riser system as the water depth gets larger due to its lower cost and easier installment. Its dynamic response and restoring performance become more complicated, as the length of the mooring-line become larger, and the structural and fluid dynamics the mooring-line become consequently more obvious. Compared to the quasi-static method where the static restoring force is mainly involved, the dynamic behaviors and its hysteresis of the catenary mooring-line are considered here so as to comprehensively examine the non-linearly restoring performance of mooring-lines. Based on the 3d dynamic vector equations along with the modified FEM simulations, the hysteresis character of the restoring stiffness and the influences of the catenary dynamics on its restoring performance are presented and discussed. It is found that, principally owing to the damping and inertial effect coming from the fluid and structural dynamics, the restoring force of the mooring-line depends on both the structural displacement and velocity. Moreover, the dynamic stiffness behaves as a hysteresis loop, instead of a curve. Our numerical results show that the energy consumption during one period rises nonlinearly with the increase of the body frequency ωd and amplitude A0. And, the influence of nonlinear restoring stiffness on the structural response along with the slack-taut phenomenon caused by structural /hydrodynamic inertia and damping is discussed.

As offshore wind turbine is developed toward larger water depth, the dynamics coming from structural and fluid inertia and damping effects of the mooring-line gets more obvious, that makes the response analysis of the large floating wind turbine under wind&wave load more challenging. In this study, the dynamic response of a spar floating wind turbine under random wind and wave loads is examined by the modified FEM simulations. Here an integrated system including flexible multi-bodies such as blades, tower, spar and mooring-lines is considered while the catenary dynamics is involved. The dynamic restoring performance of the catenary mooring-line is analyzed based on the vector equations of 3D curved flexible beam and its numerical simulations. Then the structural responses, e.g. the top tension, structural displacements and stress of the tower and the blade, undergoing random wind&wave loads, are examined. Morevoer, the influences of the catenary dynamics on its restoring performance and the hysteresis behavior are presented. Our numerical results show: the dynamics of mooring-line may significantly increase the top tension, and, particularly, the snap tension could be more than 3 times larger than the quasi-static one. Moreover, the structural response under random wind&wave load gets smaller mainly because of the hysteresis effect coming from the mooring-line dynamics. The floating body displacement at surge frequency is around 20% smaller, and the tower root stress at bending frequency is about 30% smaller than the quasi-static values respectively.

Enterovirus 71 (EV71) always induces severe hand, foot, and mouth disease with neurological complications, such as encephalitis. Interleukin (IL)-7 augments CD8

As oil and gas industry is developing towards deeper ocean area, the length and flexibility of ocean pipes become larger, which may induce larger-amplitude displacement of flexible pipe response due to lower structural stiffness against environmental and operational loads. Moreover, these pipes also convey internal flow. In other words, the dynamic characteristics and response of the flow-conveying pipe face great challenge, such as bucking and flutter. In this study, the dynamic characteristics and response of a flexible pipe, under internal flow and, particularly, axially-varying tension, are examined through our FEM numerical simulations. First, the governing equations and FEM models of a flexible pipe with axially-varying tension and internal flow are developed. Then the dynamic characteristics, including the coupled frequency and modal shape, are presented. At last, the dynamic response and corresponding stability behaviors are discussed and compared with the cases of pipe with uniform tension. Our FEM results show that the stability and response are quite different from pipe with uniform tension. And, the time-spatial evolution of pipe displacement exhibits a profound wave propagation effect, e.g. the wave length and peak value/position significantly change along structural length and the mechanism is discussed based on the WKB solutions.

MicroRNAs (miRs) are a class of endogenous small non-coding RNAs that have been revealed to negatively mediate the expression of their target genes at the post-transcriptional level. Recently, particular miRs have demonstrated an involvement in the pathogenesis of Alzheimer's disease (AD). However, the specific role of miR-135b in AD has yet to be elucidated. The present study aimed to investigate the neuroprotective role of miR-135b, in addition to its underlying mechanism. Herein, reverse transcription-quantitative polymerase chain reaction was conducted to determine miR-135b expression levels in the peripheral blood samples of patients with AD and age-matched normal controls. The data of the present study revealed that the expression levels of miR-135b were significantly reduced in the peripheral blood of AD patients compared with normal controls (P

Most of the floating tunnel and supporting tendon or cable of submerged floating tunnel (SFT) are essentially cylindrical body. Multi-mode vortex- induced vibration (VIV) of these flexible bodies frequently happens in non-uniform flow due to structural flexibility and non-uniform distribution of fluid velocity. One of the challenging issues of multi-mode VIV is about mode competition. And the mechanism and its quantitively measurement of mode competition, in terms of excitation region and length of potentially participating modes along with modal weights, become more complicated than single-mode VIV. In this study, mode competition and multi-mode VIV of flexible body in lineally sheared current is explored based on our numerical simulations which combine finite element approach with a hydrodynamic model so as to carry out nonlinearly simultaneously dynamic response in time domain. Our numerical results show that multi-mode VIV may occur both in non-uniform and uniform fluid profiles. In sheared current, as the towing speed (or the maximum speed) increases, because more modes with higher modal order number participate into the dynamic response, the average RMS displacement just change a little while the average RMS stress progressively rises. Moreover, there are different dominant frequencies distributing along cylinder span, and the length of the first dominant frequency gets smaller due to larger shearing parameter along with more intense competition between all participating modes. (C) 2016 The Authors. Published by Elsevier Ltd.

In deeper ocean area, more and more floating oil/gas production platforms or wind turbine have been in operation instead of the fixed truss in shallow water. These floaters need to be located among a range of position by its mooring system, e.g. tension tendon and catenary mooring-line, so as to guarantee structural safety and stability under environmental loads. Catenary mooring-line is increasingly used due to its lower cost and easier installation. Its dynamics coming from structure and fluid flow becomes more obvious with the increase of structural length, which may introduce significant impact on restoring performance of mooring-line. In this study, the non-linearly restoring performance and the hysteresis behavior of mooring-line's stiffness are studied. The nonlinear dynamic model of the mooring-line is established based on the improved FEM simulations. It is found that the restoring stiffness of the catenary mooring-line presents a hysteresis characteristic, principally owing to the damping effect of the catenary dynamics, which gets more obvious with the increase of motion amplitude/frequency. And, the mooring-line dynamics has significant impacts on the tension (related to its restoring stiffness) and displacement response, e.g. the maximum tension amplitude is up to 5.2 times of the quasi-static value if slack happens.

As the output power of wind turbine increasingly gets larger, the structural flexibility of elastic bodies, such as rotor blades and tower, gets more significant owing to larger structural size. In that case, the dynamic interaction between these flexible bodies become more profound and may significantly impact the dynamic response of the whole wind turbine. In this study, the integrated model of a 5-MW wind turbine is developed based on the finite element simulations so as to carry out dynamic response analysis under random wind load, in terms of both time history and frequency spectrum, considering the interactions between the flexible bodies. And, the load evolution along its transmitting route and mechanical energy distribution during the dynamic response are examined. And, the influence of the stiffness and motion of the supporting tower on the integrated system is discussed. The basic dynamic characteristics and responses of 3 models, i.e. the integrated wind turbine model, a simplified turbine model (blades, hub and nacelle are simplified as lumped masses) and a rigid supported blade, are examined, and their results are compared in both time and frequency domains. Based on our numerical simulations, the dynamic coupling mechanism are explained in terms of the load transmission and energy consumption. It is found that the dynamic interaction between flexible bodies is profound for wind turbine with large structural size, e.g. the load and displacement of the tower top gets around 15% larger mainly due to the elastic deformation and dynamic behaviors (called inertial-elastic effect here) of the flexible blade; On the other hand, the elastic deformation may additionally consume around 10% energy (called energy-consuming effect) coming from external wind load and consequently decreases the displacement of the tower. In other words, there is a competition between the energy-consuming effect and inertial-elastic effect of the flexible blade on the overall dynamic response of the wind turbine. And similarly, the displacement of the blade gets up to 20% larger because the elastic-dynamic behaviors of the tower principally provides a elastic and moving support which can significantly change the natural mode shape of the integrated wind turbine and decrease the natural frequency of the rotor blade.

For case of oil/gas exploitation and mining in deep water, the length of riser is pretty large and, consequently, it brings huge challenges in both offshore installation and production operations and results in significant cost elevation due to the factors such as extreme tension loads induced from riser suspended self-weight and large structural flexibility. Therefore, there are several alternative riser configurations, e.g. lazy wave, hybrid tower and lazy-wave riser beside free hanging catenary, which have been proposed. In this paper, the dynamic characteristics and responses of several risers with typical configurations are considered and compared with each other based on our numerical simulations. Firstly, the nonlinear dynamic model of the riser systems are developed based on our 3d dynamic riser equations along with the modified FEM simulations. Then the dynamic response is analyzed based on our 3d curved flexible beam approach where the structural curvature changes with its spatial position and time in terms of vector equations. Compared with the linear approach, the nonlinear FEM method is used so as to consider large displacement/deformation, configuration geometry and structural stiffness changing with body motion. Moreover, the hydrodynamic force is considered as being related to body motion too. Based on the FEM numerical simulations, the influences of the amplitude/frequency of the top vessel motion along with the buoyancy modules/tower distribution along structural length on riser’s dynamic responses, in terms of the temporal-spatial evolution of displacement, curvature/bending stress and dynamic tension, are studied for different riser’s configurations. Our results show that the dynamic responses, particularly the maximum top tension, of different riser systems significantly change. Among the examined riser configurations, the response of the riser with more buoyancy modules may have lower value, and buoyancy distribution along structural length can influence the top tension and curvature.

Si-H bond activation is an important process implicated in many useful synthetic applications including silylation and transfer hydrogenation reactions. Herein we discovered homolytic activation of Si-H bonds on the surface of nanoporous gold (NPG), forming hydrogen radicals and [Au]-[Si] intermediates. By virtue of this new reactivity, we achieved highly selective mono and sequential alcoholysis of dihydrosilane. In addition, the amphiphilic nature of the [Au]-[Si] intermediate allows for a new bis-silylation reaction of cyclic ethers. The present work showcased that the surface reactivity of nanocatalysts may provide exciting opportunity for new reaction discovery.

The mechanisms of epilepsy remain incompletely understood. Rac1 (ras-related C3 botulinum toxin substrate 1) belongs to the Rho family of small GTPases. Rac1 play important roles in cytoskeleton rearrangement and neuronal synaptic plasticity, which had also been implicated in epilepsy. However, little is known regarding the expression of Rac1 in the epileptic brain or whether Rac1-targeted interventions affect the progression of epilepsy. The aim of this study was to investigate the expression profile of Rac1 in brain tissues from patients suffering from temporal lobe epilepsy (TLE) and experimental epileptic rats and determine the possible role of Rac1 in epilepsy. We demonstrated that the expression of Rac1 is significantly increased in TLE patients and in lithium-pilocarpine epilepsy model animals compared to the corresponding controls. Rac1 inhibitor NSC23766 reduced the severity of status epilepticus during the acute stage in a lithium-pilocarpine animal model. Consistent with these results, the latent period of a PTZ kindling animal model also increased. Our results demonstrated that the increased expression of Rac1 may contribute to pathophysiology of epilepsy.

The dynamic coupling between moving top-end vessel and submarine riser becomes more remarkable for floating platform in deep water due to its larger amplitude of top-end motion, compared to fixed platform in shallow water. The impacts of top-end motion on the riser undergoing vortex-induced vibration (VIV) are explored in this study. A coupled hydrodynamic force approach, involving the vortex-induced lift force along with the fluid drag force, is developed, which takes into account the interaction between fluid dynamic force and instantaneous riser motion. Then the dynamic behaviors of the riser suffering both top-end motion and VIV are examined by means of finite element simulations. The effects of the amplitude and frequency of top-end vessel sway on riser's VIV are studied. During the riser's dynamic responses, an interesting phenomenon, called nonlinear response amplification, is observed, which demonstrates that top-end motion may be amplified as the motion propagates along riser length. Our numerical results show that the riser's displacement becomes several times larger than that of the case without top-end motion. Moreover, the nonlinear amplification gets more pronounced as the number of mode order drops, but the amplification factor just slightly changes with the increase of sway amplitude. (C) 2015 Elsevier Ltd. All rights reserved.

Floating bodies such as oil rig/production platform and wind turbine in ocean need to be fixed or controlled at expected position by its supporting system which includes tension tendon and catenary mooring-line. Recently, the later one, catenary mooring-line, is increasingly used in deeper water due to its lower cost and easier installment. As the floating platform are developed toward deeper water depth, the length of the mooring-line become larger and consequently the dynamic behaviors such as the structural inertia and hydrodynamic inertia/damping of the mooring-line become more obvious. In this paper, the dynamic behaviors of the mooring-line are considered, and compared with the traditional quasi-static method where only the static restoring force is involved, so as to comprehensively examine the non-linearly restoring performance of catenary mooring-lines. Firstly, the nonlinear dynamic model of the mooring system is developed based on our 3d dynamic catenary equations along with the modified finite element simulations. Compared with the static restoring force, essentially depending on structural gravity and overall shape based on static catenary theory, the dynamic restoring force is analyzed based on our 3d curved flexible beam approach where the structural curvature changes with its spatial position and time in terms of vector equations. In our modified finite element simulations, the rotation degree of freedom between neighboring beam elements is released and bending stiffness of individual element is set to be zero, and the statically original shape and top tension according to the traditional static catenary theory are used as the initial conditions. Moreover, the hydrodynamic force is loaded as depending on structural motion. Based on our numerical simulations, the influences of the amplitude and frequency of the catenary’s top-end motion, along with the structural parameters (including the mass density and initial tension ratio), on mooring line’s temporal-spatial evolution of displacement and dynamic tension are studied. Also, the slack-taut phenomenon caused by structural /hydrodynamic inertia and damping are presented. Our results show: 1) Generally, the displacement distribution along the mooring-line is characterized as a stable stand wave. The additional part of restoring tension due to the dynamic effects is up to 20% of the quasi-static method, and the tension amplitude difference (between the maximum tension and minimum tension) is around three times of the quasi-static value. Particularly, as the mooring-line becomes slack, the response is characterized as travelling wave, the maximum tension amplitude is up to 9 times of the static method. 2) As the amplitude/frequency of the catenary’s top-end motion increases, the value of catenary displacement firstly drops and then rises. The displacement distribution along catenary length changes with the motion of top end. Interestingly, the maximum displacements occur at the middle point of the catenary for case of surge while the maximum displacement moves up along the catenary as the top end motion gets larger for case of heave. 3) The magnification factor of top tension drops with increase of mooring-line mass density but rises with the increase of the initial tension ratio. It is also noted the velocity amplitude at higher frequency in the velocity spectrum may increase as the top end motion increases.

Recently, wind turbine has been developed from onshore area to offshore area because of more powerful available wind energy in ocean area and more distant and less harmful noise coming from turbine. As it is approaching toward deeper water depth, the dynamic response of the large floating wind turbine experiencing various environmental loads becomes more challenge. For examples, as the structural size gets larger, the dynamic interaction between the flexible bodies such as blades, tower and catenary mooring-lines become more profound, and the dynamic behaviors such as structural inertia and hydrodynamic force of the mooring-line get more obvious. In this paper, the dynamic response of a 5MW floating wind turbine undergoing different ocean waves is examined by our FEM approach in which the dynamic behaviors of the catenary mooring-line are involved and the integrated system including flexible multi-bodies such as blades, tower, spar platform and catenaries can be considered. Firstly, the nonlinear dynamic model of the integrated wind turbine is developed. Different from the traditional static restoring force, the dynamic restoring force is analyzed based on our 3d curved flexible beam approach where the structural curvature changes with its spatial position and the time in terms of vector equations. And, the modified finite element simulation is used to model a flexible and moving catenary of which the hydrodynamic load depending on the mooring-line’s motion is considered. Then, the nonlinear dynamic governing equations is numerically solved by using Newmark-Beta method. Based on our numerical simulations, the influences of the dynamic behaviors of the catenary mooring-line on its restoring performance are presented. The dynamic responses of the floating wind turbine, e.g. the displacement of the spar and top tower and the dynamic tension of the catenary, undergoing various ocean waves, are examined. The dynamic coupling between different spar motions, i.e. surge and pitch, are discussed too. Our numerical results show: the dynamic behaviors of mooring-line may significantly increase the top tension, particularly, the peak-trough tension gap of snap tension may be more than 9 times larger than the quasi-static result. When the wave frequency is much higher than the system, the dynamic effects of the mooring system will accelerate the decay of transient items of the dynamic response; when the wave frequency and the system frequency are close to each other, the displacement of the spar significantly reduces by around 26%. Under regular wave condition, the coupling between the surge and pitch motions are not obvious; but under extreme condition, pitch motion may get about 20% smaller than that without consideration of the coupling between the surge and pitch motions.

The dynamic coupling between floating top and submarine riser becomes more remarkable owing to larger fluctuation amplitude of floating platform in deeper water, compared to fixed platform in shallow water. In this study, the impacts of top-end vertical motion (heave) on riser's vortex-induced vibration (VIV) are explored by means of finite element simulations. A coupled hydrodynamic force approach, regarding vortex-induced lift force along with fluid drag force, is developed, which takes into account of the interaction between instantaneous structure motion and fluid dynamics. Then the dynamic responses of the integrate system including both floating top-end and a riser undergoing VIV are examined based on our numerical simulations. The influences of platform heave, in terms of heave frequencies and tension ratios, on riser's VIV are presented. Our numerical results show that the dynamic response displacement of riser becomes several times larger than the displacement for the case without top-end motion. The impact of top heave on riser's VIV gets larger as the modal order number drops. Moreover, an interesting phenomenon, called the mode transition, is observed particularly at lower vibration frequencies due to the natural dynamic characteristics of the slender riser. We suggest that, in practices of riser design, a combined excitation needs to be considered for the accurate dynamic analysis of slender marine structures subjected to a top-end motion and VIV. (C) 2014 Elsevier Ltd. All rights reserved.

Oxytocin (OXT), a nonapeptide posterior hormone of the pituitary, is mainly synthesized and secreted in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). The present study was to investigate in which level, brain or periphery, OXT effecting on the behavioral activity in the behavioral despair depression rat model. The results showed that (1) either the forced swimming or the tail suspension significantly increased OXT concentration in the brain (PVN, SON, frontal cortex, hippocampus, amygdala, lumbar spinal cord) and in the periphery (posterior pituitary and serum); (2) intraventricular injection (icv) of OXT decreased the animal immobility time, whereas OXT receptor antagonist-desGly-NH2, d(CH2)5[D-Tyr2, Thr-sup-4]OV (icv) increased the animal immobility time in a dose-dependent manner in forced swimming test (FST) and in tail suspension test (TST); (3) neither OXT nor OXT receptor antagonist (intravenous injection) influenced the animal immobility time in FST and in TST. OXT levels were increased in several areas of the brain and in the periphery following the behavioral despair, one stressor, yet pre-treatment with OXT appeared to be beneficial in term of reducing immobility time. The data suggested that behavioral despair could enhance OXT synthesis and secretion not only in the brain but also in the periphery, and OXT in the brain rather than the periphery played a role in the behavioral despair depression.

Enterovirus 71 (EV71) always induces severe hand, foot, and mouth disease with neurological complications, such as encephalitis. Interleukin (IL)-7 augments CD8+ T cells activity in chronic viral infection and cancers. However, few studies have focused on common γ-chain (γc) cytokine expression and regulatory function of IL-7 to CD8+ T cells in EV71 associated encephalitis. In this study, twenty-one patients with EV71 associated encephalitis, twenty-seven patients with febrile convulsion (FC), and twenty healthy individuals were enrolled. γc cytokine (IL-2, IL-4, IL-7 and IL-15) concentration was measured by ELISA. IL-7 receptor α chain (membrane/soluble CD127) expression was also investigated. Purified CD8+ T cells were stimulated with recombinant human IL-7 in vitro. The regulatory activity of IL-7 to CD8+ T cells from peripheral blood and cerebrospinal fluids (CSF) was investigated in direct and indirect contact co-culture with U-87MG cells. IL-7 in the serum and CSF, but not IL-2, IL-4, or IL-15, was significant increased in EV71 associated encephalitis. Both total CD127 mRNA relative level and membrane/soluble CD127 expression was comparable among three groups. IL-7 stimulation promoted CD8+ T cells proliferation, up-regulated perforin/granzyme B level, but reduced programmed death-1 expression in CD8+ T cells from EV71 associated encephalitis patients. Cytotoxicity and interferon-γ production of CD8+ T cells from peripheral blood and CSF was also augmented in response to IL-7 stimulation in both direct and indirect co-culture systems in EV71 associated encephalitis. The present data indicated that IL-7 induced cytolytic and non-cytolytic functions of CD8+ T cells in EV71 associated encephalitis. IL-7 might be considered as one of the immunomodulatory therapeutic candidates for EV71 infection.

Despite recent advances in phosphoproteomics, an efficient and simple enrichment protocol is still a challenge and of high demand aiming at large-scale plant phosphoproteomics studies. Here, we developed a novel loading buffer system for synthesized immobilized metal affinity chromatography material targeting plant samples, which was prepared by a simple one-step esterification between polyvinyl alcohol and phosphoric acid and then was subjected to immobilize Ti(4+). SEM and Fourier transform IR spectroscopy were used to assure the synthesis protocol of the polyvinyl alcohol-based Ti(4+) immobilized material, and the specific surface areas and pore volumes of the polymers were measured. The selectivity for phosphopeptide enrichment from α-casein was improved by optimizing the pH and components of the loading buffer. By using potassium hydrogen phthalate/hydrochloric acid with pH at 2.50 as the loading buffer, 19 phosphopeptides with high intensity were identified. The final optimized protocol was adapted to salt-stressed maize leaves for phosphoproteome analysis. A total of 57 phosphopeptides containing 59 phosphorylated sites from 50 phosphoproteins were identified in salt-stressed maize leaf. The research was meaningful to obtain much more information about phosphoproteins leading to the comprehension of salt resistance and salt-inducible phosphorylated processes of maize leaves.

Salinity is one of the most common abiotic stresses encountered by plants. Reversible protein phosphorylation is involved in plant defense processes against salinity stress. Here, we performed global phosphopeptide mapping through enrichment by our synthesized PVA-phosphate-Ti(4+) IMAC coupled with subsequent identification by ESI-Q-TOF MS. A total of 104 peptide sequences containing 139 phosphorylation sites were determined from 70 phosphoproteins of the control leaves. In contrast, 124 phosphopeptides containing 143 phosphorylated sites from 92 phosphoproteins were identified in salt-stressed maize leaves. Compared with the control, 47 proteins were phosphorylated, 25 were dephosphorylated, and 45 overlapped. Among the 72 differential phosphoproteins, 35 were known salt stress response proteins and the rest had not been reported in the literature. To dissect the differential phosphorylation, gene ontology annotations were retrieved for the differential phosphoproteins. The results revealed that cell signaling pathway members such as calmodulin and 14-3-3 proteins were regulated in response to 24-h salt stress. Multiple putative salt-responsive phosphoproteins seem to be involved in the regulation of photosynthesis-related processes. These results may help to understand the salt-inducible phosphorylation processes of maize leaves.

Silacyclobutane was discovered to be an efficient C−H bond silylation reagent. Under the catalysis of RhI/TMS-segphos, silacyclobutane undergoes sequential C−Si/C−H bond activations, affording a series of π-conjugated siloles in high yields and regioselectivities. The catalytic cycle was proposed to involve a rarely documented endocyclic β-hydride elimination of five-membered metallacycles, which after reductive elimination gave rise to a Si−RhI species that is capable of C−H activation.

An oxidative cyclization of o-alkyl substituted benzoic acids through a Ritter-type reaction with acetonitrile is described to provide N-acetyl substituted lactams in moderate to good yields.

Silacyclobutane was discovered to be an efficient C-H bond silylation reagent. Under the catalysis of Rh(I) /TMS-segphos, silacyclobutane undergoes sequential C-Si/C-H bond activations, affording a series of π-conjugated siloles in high yields and regioselectivities. The catalytic cycle was proposed to involve a rarely documented endocyclic β-hydride elimination of five-membered metallacycles, which after reductive elimination gave rise to a Si-Rh(I) species that is capable of C-H activation.

We report a Cu/Fe co-catalyzed Ritter-type C-H activation/amination reaction that allows efficient and selective intermolecular functionalization of benzylic C-H bonds. This new reaction is featured by simple reaction conditions, readily available reagents and general substrate scope, allowing facile synthesis of biologically interesting nitrogen containing heterocycles. The Cu and Fe salts were found to play distinct roles in this cooperative catalysis.

Activated microglia are capable of facilitating amyloid-β (Aβ) accumulation via the release of inflammatory factors, thus resulting in the exacerbation of Alzheimer's disease (AD). MicroRNAs (miRs) participate in the activation of microglia, which is associated with AD. Insulin-like growth factor 1 (IGF1) is a neuroprotective, anti-inflammatory factor, which is able to accelerate clearance of Aβ peptides. The present study aimed to investigate the precise role of miR‑206 and IGF1 in lipopolysaccharide (LPS)‑induced microglial inflammation. The expression levels of miR‑206 and IGF1 were detected in 60 peripheral blood samples from patients with AD and matched age subjects using quantitative polymerase chain reaction. A dual luciferase reporter gene assay was used to indicate the relationship between miR‑206 and IGF1. In addition, the role of miR‑206 was determined by gain and loss of function experiments in LPS‑treated microglia. The results demonstrated that miR‑206 upregulation enhanced LPS‑induced inflammation and Aβ release in microglia by directly targeting the 3'-untranslated region of IGF1. These effects were attenuated following treatment with exogenous IGF1, thus indicating that the miR‑206/IGF1 signaling pathway may be considered a novel therapeutic target for the treatment of AD‑associated microglial inflammation.

The dynamic coupling between moving top-end vessel and submarine riser becomes more remarkable for a floating platform in deeper water due to the larger top-end motion amplitude, compared with the fixed platform in shallow water. In this study the impacts of top-end heave on the riser undergoing vortex-induced vibration (VIV) are explored in terms of the parametric excitation and the consequent dynamic behaviors. By using finite element simulations based on a coupled hydrodynamic force approach, the dynamic responses of the integrated system including both a floating top-end and the riser experiencing VIV are examined. Our numerical results show that the riser displacement becomes several times larger than the displacement for the case without top-end motion, and the impact of heave on riser VIV response gets larger as the modal order number dropping. Riser VIV amplitude becomes, almost linearly, more profound when the tension ratio, as one of critical parameters that influence the riser dynamic response, gets larger. Moreover, an interesting phenomenon called mode transition is observed, particularly at lower frequency, during modal dynamics response.

The impacts of top-end motion on the riser undergoing vortex-induced vibration (VIV) are explored in this study, because the dynamic coupling between moving top-end vessel and submarine riser becomes more remarkable for a floating platform in deeper water due to the larger top-end motion amplitude, compared with the fixed platform in shallow water. A coupled hydrodynamic force approach, involving the vortex-induced lift force along with the fluid drag force, is developed. The dynamic responses of the system including a floating top-end and a riser experiencing VIV are examined by means of finite element simulations. The effects of amplitude and frequency of top-end vessel sway on riser VIV are examined. Our numerical results show that the riser displacement becomes several times larger than the displacement for the case without top-end motion. Moreover, the nonlinear response amplification is observed, and the nonlinear amplification gets more pronounced as the number of mode order dropping, while the amplification factor just slightly changes with the increase of sway amplitude.

Despite recent advances in phosphoproteomics, an efficient and simple enrichment protocol is still a challenge and of high demand aiming at large-scale plant phosphoproteomics studies. Here, we developed a novel loading buffer system for synthesized immobilized metal affinity chromatography material targeting plant samples, which was prepared by a simple one-step esterification between polyvinyl alcohol and phosphoric acid and then was subjected to immobilize Ti(4+). SEM and Fourier transform IR spectroscopy were used to assure the synthesis protocol of the polyvinyl alcohol-based Ti(4+) immobilized material, and the specific surface areas and pore volumes of the polymers were measured. The selectivity for phosphopeptide enrichment from α-casein was improved by optimizing the pH and components of the loading buffer. By using potassium hydrogen phthalate/hydrochloric acid with pH at 2.50 as the loading buffer, 19 phosphopeptides with high intensity were identified. The final optimized protocol was adapted to salt-stressed maize leaves for phosphoproteome analysis. A total of 57 phosphopeptides containing 59 phosphorylated sites from 50 phosphoproteins were identified in salt-stressed maize leaf. The research was meaningful to obtain much more information about phosphoproteins leading to the comprehension of salt resistance and salt-inducible phosphorylated processes of maize leaves.