Two-dimensional Fe3O4/MoS2 nanocomposites for a magnetorheological fluid with enhanced sedimentation stability.

Superparamagnetic Fe3O4 nanoparticles were successfully deposited on the surface of MoS2 nanosheets (Fe3O4/MoS2) by a sonochemical method and the obtained Fe3O4/MoS2 nanocomposites were used as a promising candidate for a magnetorheological (MR) fluid. This MR fluid was prepared from the Fe3O4/MoS2 nanocomposites and its corresponding MR performances were examined using a rotational rheometer. The MR fluid based on Fe3O4/MoS2 showed typical MR effects with increasing viscosity, shear stress, yield stress and dynamic shear modulus depending on the applied magnetic fields. Compared with commercial carbonyl iron (CI) particles, the sedimentation stability of the Fe3O4/MoS2-MR fluid was greatly improved because of its unique two-dimensional structure and the reduced fluid-particle density mismatch. Therefore, the prepared Fe3O4/MoS2-based MR fluid with typical MR effects and good sedimentation stability would have great potential in practical applications.

Reliability Evaluation and Robust Design of a Sensor in an Entire Roller-Embedded Shapemeter.

The intermittence of the shape detection signal associated with an entire roller-embedded shapemeter roll, used in a seven-pass cold reversible rolling process, is considered. A transient interference at the sensor top surface and the distance between the sensor top surface and the roll outer surface are developed, and a sensor reliability evaluation model is derived. The reliability of the sensor is evaluated via the random perturbation method, and the reliability sensitivity of design variables is proposed. The analysis reveals that the reliability is smallest in the third rolling pass. Of the design variables considered, the initial interference exhibits the largest reliability sensitivity and has the greatest influence on the sensor reliability. A reliability robust design model of the initial interference is therefore developed. A new shapemeter roll is fabricated and tested in a 1050 reversible cold rolling mill. The test results are consistent with the theoretical results, thereby validating the proposed model. The selection of an appropriate initial interference provides an important means of overcoming the adverse effects associated with the thermal deformation of sensor contact surfaces.

Polymeric membrane potentiometric sensors based on template-removal-free imprinted receptors for determination of antibiotics.

Currently, Nernstian-response-based polymeric membrane potentiometric sensors using molecularly imprinted polymers (MIPs) as receptors have been successfully developed for determination of organic ionic species. However, the preparation of these MIP receptors usually involves tedious and time-consuming template-removal procedures. Herein, a template-removal-free MIP is proposed and used as a receptor for fabrication of a potentiometric sensor. The proposed methodology not only significantly shortens the preparation time of MIP-based potentiometric sensors but also improves the batch-to-batch reproducibility of these sensors. By using antibiotic vancomycin as a model, the new concept offers a linear concentration range of 1.0 × 10-7 to 1.0 × 10-4 mol L-1 with a detection limit of 2.51 × 10-8 mol L-1. It can be expected that the template-removal-free MIP-based sensing strategy could lay the foundation for simple fabrication of electrochemical sensors without the need for template removal such as potentiometric and capacitive sensors and ion-sensitive field-effect transistors.

Potentiometric sensor based on a computationally designed molecularly imprinted receptor.

Molecularly imprinted polymer (MIP)-based polymeric membrane potentiometric sensors are ideal candidates for detection of organic species. The development of such sensors has opened new attractive horizons for potentiometric sensing. However, it should be noted that in the preparation of these MIP receptors, the selection of the functional monomer usually depends on empirical trial- and error-based optimization, which involves tedious and time-consuming experiments. In this work, the computer-aided design and synthesis of an MIP receptor are applied in the fabrication of an MIP-based potentiometric sensor. The density functional theory calculation with the B3LYP model and 6-31G(d) basis set is used to study the interactions between the functional monomer and template molecules. The binding energies of the complexations between the template molecule and different functional monomers are used as a criterion for the selection of the proper monomer. The designed MIP is then synthesized and employed as the receptor for the fabrication of the potentiometric sensor. As a proof-of-concept experiment, the antibiotic sulfadiazine has been selected as a model and 4 functional monomers, 2-hydroxyethyl methacrylate, methyl methacrylate, N-isopropylacrylamide and N-phenylacrylamide, have been chosen. The designed MIP-based sensor exhibits excellent sensitivity with a linear range of 1-10 µM and also shows a good selectivity. We believe that the proposed computer-aided synthesis technique for the MIP receptor selection can provide a general and facile way to replace the traditional empirical MIP preparation method in the fabrication of MIP-based electrochemical and optical sensors.

A generalized predictive control for remote cardiovascular surgical systems.

Robot-assisted cardiovascular surgery is used to avoid surgeon suffering from X-ray radiation and relieve fatigue caused by long-time standing wearing protective clothing. Its remote surgery can alleviate the lack of experienced doctors in remote areas. Due to the existence of time-delay phenomena, flexible deformation and nonlinearity of interventional instruments, it is difficult to ensure system transparency. This paper analyzes the evaluation index of system transparency. A generalized predictive control (GPC) is developed to suppress the effect of time-varying delay and parameter identification error. Moreover, a terminal sliding mode controller (SMC) is designed to improve the robustness of the system under consideration. Simulation results are provided to show that the proposed control strategy can improve transparency of the remote vascular interventional surgery system.

[Effects of anti-CD25 monoclonal antibody on the level of cytokines in aqueous humour after rat penetrating keratoplasty].

OBJECTIVE: To investigate the toxicity of anti-CD25 monoclonal antibody (mAb) to rat cornea and its effects on the cytokines in the aqueous humour after penetrating keratoplasty (PKP), thereby evaluating the effect of anti-CD25 mAb in preventing corneal allograft rejection. METHODS: The corneal toxicity of anti-CD25 mAb at 50, 100 and 200 microg administered via subconjunctival injection was evaluated in 12 SD rats by histological examination and transmission electron microscopy. Another 93 SD rats were randomized into 5 groups, and transplantation of corneal allograft from Wistar rats was performed in 4 groups with the other group as the normal control. The 4 allograft groups were treated with saline, 100 microg anti-CD25 mAb, 100 microg anti-CD25 mAb with 50 microg dexamethasone, and 50 microg dexamethasone, respectively. The graft rejection was observed, the aqueous humour levels of IFN-gamma and IL-4 were measured with ELISA, and IFN-gamma mRNA expressions in the grafts detected with RT-PCR. RESULTS: anti-CD25 mAb at 50 or 100 microg did not show significant toxicity on the cornea, but at 200 microg, the mAb caused swelling of the corneal stromal cells and endothelial cells. After corneal allograft transplantation, a significant delay in allograft rejection was observed in the 3 groups with mAb or dexamethasone treatment as compared with that in saline group (P<0.05). IFN-gamma mRNA expression in the allograft on days 11 after PKP and in the aqueous humour on days 6 and 11 was markedly increased in saline group compared with that in the 3 treatment groups (P<0.05). The mean IL-4 level in the aqueous humour was significantly higher in the mAb group than in saline group (P<0.05), but markedly lower in anti-CD25 mAb+dexamethasone and dexamethasone groups than in anti-CD25 mAb group (P<0.05). CONCLUSIONS: Anti-CD25 mAb at 20 and 100 microg does not obviously affect the rat corneas. Anti-CD25 mAb inhibits IFN-gamma expression and promotes IL-4 the expression to reduce corneal allograft rejection, whereas anti-CD25 mAb with low-dose dexamethasone inhibits both IFN-gamma and IL-4 expressions to more effectively promote the graft survival.