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Silver decorated titania nanorod array (Ag/TiO 2 NRA) and nanopore array (Ag/TiO 2 NPA) had been designed as surface-enhanced Raman scattering (SERS) active substrate for a sensitive detection application. TiO 2 NRA grown on glass slide was fabricated through hydrothermal synthesis process. TiO 2 NPA grown on the titanium sheet was fabricated by a two-stepped anodization process. Ag/TiO 2 NRA and Ag/TiO 2 NPA were formed by depositing silver nanoparticles on TiO 2 nanoarray through an electroless deposition process. Ag/TiO 2 NRA had smaller silver interparticle gaps and more hot-spots than Ag/TiO 2 NPA, exhibiting a higher SERS activity. The analytical enhancement factor was accordingly increased from 1.8 × 10 5 for Ag/TiO 2 NPA up to 7.8 × 10 5 for Ag/TiO 2 NRA. Ag/TiO 2 NRA substrate achieved a very low detection limit of 5 × 10 −12 M 4-mercaptobenzoic acid as a probe molecule, showing a sensitive SERS detection performance. Ag/TiO 2 NRA also conducted photocatalysis decomposition of these adsorbed organic molecules to recover a clean surface under UV irradiation, exhibiting a self-cleaning activity. Such an Ag/TiO 2 nanoarray with well-controlled size and shape could be suitably applies as a self-cleaning SERS substrate, showing high reproducibility and cycleability in recycling SERS detection application.

Dextran coated GoldMag nanoparticles (DGMNs) were synthesized, characterized and demonstrated to be effective vehicles for targeted drug delivery. Characterization of DGMNs by Fourier Transform Infrared Spectroscopy showed that their surface contained dextran whereas x-ray diffraction studies revealed that the particles were uniform with the expected crystalline structure. In thermo-gravimetric analysis studies, dextran accounted for 50% of the mass in the DGMN particles. DGMNs had an average diameter of 106 nm which can potentially prevent flocculation via steric stabilization. The blue shift of surface enhanced plasmon resonance absorption peaks observed during UV-Vis studies was indicative that DGMNs were colloidal-dispersed and uniform in size. Lastly, the dextran coating did not affect GoldMag particles' inherent property of magnetism-saturation magnetization of DGMNs was efficient and fast-acting to external magnetic field (23.5 emu/g). In vitro drug studies showed that the cancer drug doxorubicin binds effectively to DGMNs and is steadily/controllably released from the particle surface in physiological conditions when compared to their parental GoldMag particles.

A facile synthesis for novel loperamide analogs as potential#956; opioid receptors is described. The synthetic procedure for compound 5, which contains two 4-phenyl piperidine scaffolds, was optimized, and this compound was synthesized in excellent yield. We also describe a mild and highly efficient protocol for the synthesis of compounds 6 and 7.

Curcumin, a polyphenol extracted from turmeric (Curcuma longa), has emerged as a potent multimodal cancer-preventing agent. It may attenuate the spread of cancer and render chemotherapy more effective. However, curcumin is neither well absorbed nor well retained in the blood, resulting in low efficacy. In an attempt to enhance the potency and to improve the bioavailability of curcumin, new delivery agents, hydroxypropyl-beta-cyclodextrin (HP-β-CD)-modified GoldMag nanoparticles (CD-GMNs) were designed and synthesized to incorporate curcumin. The CD-GMNs were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermo-gravimetric Analysis (TGA), X-ray Diffraction (XRD), Dynamic Light Scattering measurements (DLS), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM) analyses. For the magnetic carrier of CD-GMNs, the content of HP-β-CD was 26.9 wt%. CD-GMNs have a saturation magnetization of 22.7 emu/g with an average hydrodynamic diameter of 80 nm. The curcumin loading, encapsulation efficiency and releasing properties in vitro were also investigated. The results showed that the drug encapsulation ratio was 88% and the maximum curcumin loading capacity of CD-GMNs was 660 μg/5 mg. In vitro drug release studies showed a controlled and pH-sensitive curcumin release over a period of one week. Collectively, our data suggest that HP-β-CD-modified GoldMag nanoparticles can be considered to form a promising delivery system for curcumin to tumor sites. Targeting can be achieved by the combined effects of the application of an external magnetic field and the effect on drug release of lower pH values often found in the tumor microenvironment.

Subharmonic oscillations exist in digital-average-current-controlled switching dc-dc converters with trailing- and leading-edge modulations. To eliminate these subharmonic oscillations, a digital-triangle-compensation (DTC) method is proposed in this letter. The DTC method can easily be implemented in digital way without an extra compensation circuit. Experimental results are given to verify the analysis results.

A new fluorescent chemosensor based on a Rhodamine B and a benzyl 3-aminopropanoate conjugate (RBAP) was designed, synthesized, and structurally characterized. Its single crystal structure was obtained and analyzed by X-ray analysis. In a MeOH/H2O (2:3, v/v, pH 5.95) solution RBAP exhibits a high selectivity and excellent sensitivity for Sn2+ ions in the presence of many other metal cations. The binding analysis using the Job’s plot suggested the RBAP formed a 1:1 complex with Sn2+.

A mathematical model of lead (Pb) transferring in soil-vegetable system was described. In addition, the relationships among irrigating water quality, soil residual rate and plant enrichment coefficients were deduced. Finally, the model was validated at the irrigation district of Zhengzhou. It has been indicated that the simulating value was well in line with the data of measure.

Valley V2 control technique for switching converters is proposed in this paper. By utilizing output voltage ripple as pulse-width modulation ramp and valley voltage of output voltage ripple as additional control variable, valley V2 control technique provides faster load transient response than conventional current-mode control techniques. Steady-state and transient performances of switching converters with valley V2 control, peak V2 control, and current-mode control are compared and verified by experimental results.

Aspergillus Niger and Pseudomonas fluorescens have the ability to absorb heavy metals during the stationary phase of growth. To improve the removal the efficiency of the oxidation ditch, we have introduced Aspergillus Niger and Pseudomonas fluorescens to the traditional Carrousel oxidation ditch process and the comparative experimental study were carried out when the Hydraulic Retention Time (HRT) was 36h. According to the HRT of the oxidation ditch in the criterion, six different HRTs of 12h, 16 h, 20 h, 24 h, 28 h, and 32 h were considered to study the degradation of cadmium (Cd), chromium (Cr), lead (Pb) and copper (Cu) by Aspergillus Niger or Pseudomonas fluorescens which was introduced to the oxidation ditch process, respectively. The results indicated that the removal efficiency of the four heavy metals by each of the two strains compared to the control group was improved significantly, and the removal increased with the increasing HRT. When the HRT was 20h, the removal of the four heavy metals by the Aspergillus Niger was found to be in the range of 52% to 91%, and the removal of Pseudomonas fluorescens reached more than 70%. Most of the heavy metals can be degraded at the HRT of 20h, and this time is exactly the conventional design parameter of oxidation ditch. It can be say that the removal efficiency of heavy metals can be significantly improved after introduced Aspergillus Niger and Pseudomonas fluorescens to the traditional Carrousel oxidation ditch process.

The ro-ro ship loading optimization problem is discussed, in which some realistic restrictions such as vessel stability, loading efficiency and profit of voyage are considered. A 0–1 mixed integer programming model is proposed and a two-phase heuristics algorithm is developed on the basis of a greedy algorithm. Through an empirical research plus large-scale simulation experiments, the validity and practicability of the modeling and optimized algorithm are verified by means of comparisons with the exact solutions of small-sized problems and the loading plans from practical dispatching rules.

Constant on-time (COT) digital peak voltage (DPV) control of switching dc-dc converter is proposed in this paper. The COT-DPV control technique is investigated and compared with pulse width-modulated DPV (PWM-DPV) control technique by taking COT-DPV and PWM-DPV controlled buck converter in continuous conduction mode (CCM) as an example. The steady-state and transient performances of COT-DPV and PWM-DPV controlled buck converters are analyzed and compared in detail. The experimental results are given to verify the analysis results.

Conventional leading-triangle modulation is essentially a symmetrical leading-triangle modulation. To overcome the subharmonic oscillations of improved digital valley current (IDVC) controlled switching dc-dc converters with symmetrical leading-triangle modulation, asymmetrical leading-triangle modulation technique for IDVC controlled switching dc-dc converters is studied in this paper. The subharmonic oscillations of IDVC control with symmetrical leading-triangle modulation can be avoided with asymmetrical leading-triangle modulation. Experimental results show that the control performance of IDVC controlled switching converters with asymmetrical leading-triangle modulation is better than that with symmetrical leading-triangle modulation.

The operation principle of V2 controlled buck converter operating in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are analyzed. It is pointed out that V2 control is essentially a kind of control technique by utilizing peak output voltage as a control variable, quite similar to peak current-mode control. Stabilities of V2 controlled buck converter operating in CCM and DCM are analyzed in detail. It is concluded that V2 controlled buck converter is stable in CCM when duty ratio is less than 0.5 and in DCM for the whole range of duty ratio. When duty ratio is larger than 0.5, subharmonic oscillation of V2 controlled buck converter operating in CCM can be eliminated by using slope compensation. Simulation and experiment results are given to verify analysis results.

Pulse frequency modulation (PFM) includes constant on-time (COT) modulation and constant off-time (CFT) modulation. Digital V2 control technique includes digital peak voltage (DPV) control and digital valley voltage (DVV) control. In this paper, DVV controlled buck converter with COT modulation and DPV controlled buck converter with CFT modulation are studied. Their control algorithms are introduced in detail. Based on which, small-signal models of digital PFM V2 controlled buck converter are derived. Small-signal analysis is subsequently performed and compared between these two control methods.

Improved digital peak current (IDPC) control technique of switching dc-dc converters with single-edge (trailing-edge and leading-edge) and dual-edge (leading-triangle and trailing-triangle) pulse-width modulations is studied in this paper. The control laws by using these four modulation methods are derived and compared with buck converter as an example. Their stabilities are analyzed and small-signal analysis is performed with comparison among these four different modulation methods, and the corresponding Bode-Graphs of transfer functions are also given to show the difference among these different modulation methods.

Sub-harmonic oscillations of digital peak current (DPC) and digital valley current (DVC) controlled switching dc-dc converters operating in the continuous conduction mode (CCM) are analyzed in this paper. The control laws of DPC and DVC control and their corresponding sub-harmonic oscillations are studied. Digital slope compensation (DSC) method is proposed to eliminate the sub-harmonic oscillations of conventional DPC control with trailing-edge modulation and DVC control with leading-edge modulation. It is pointed out that no sub-harmonic oscillations exists in both DPC controlled converters with leading-edge modulation and DVC controlled converters with trailing-edge modulation, and improved transient performance can also be achieved in this case. Experimental results are given to verify the analysis results.

Digital peak current (DPC) control, digital peak voltage (DPV) control, and digital peak voltage/peak current (DPV/DPC) control of buck converter with leading-edge modulation are studied and compared in this paper. The ac small signal transfer functions of control-to-output, input-to-output and output impedance are derived and the corresponding comparison studies are performed. Transient simulation is also performed to verify the analysis results.

Digital peak current (DPC) controlled switching dc-dc converters operating in discontinuous conduction mode (DCM) with four different digital pulse-width modulations are studied in this paper. The control laws by using four modulation methods are derived and compared with buck converter as an example. Their stabilities are also analyzed. Experiment studies are performed to compare the transient performance among four modulation methods. Experimental results show that DPC with trailing-triangle modulation has the fastest transient response to load variation.

In this paper, improved digital peak current (IDPC) controlled boost converter with leading-edge modulation, trailing-edge modulation, leading-triangle modulation, and trailing-triangle modulation is studied. Basing on the control algorithms of IDPC with these four pulse-width modulations, the small-signal models of IDPC controlled boost converter are derived. Small-signal analysis is subsequently performed and compared among these four different modulation methods.

The operation principle and the stability of V2C controlled boost converter operating in continuous conduction mode (CCM) is analyzed in this paper. It is found that V2C control is essentially a kind of control technique utilizing peak capacitor voltage and inductor current, quite similar to peak current control. Its corresponding control waveform and the sub-harmonic oscillation are investigated subsequently. It is shown that sub-harmonic oscillation can be eliminated by slope compensation. Simulation results are given to verify analysis results.

A novel class of H3 receptor antagonists, XB-1 analogues based on benzophenone or oxydibenzene scaffolds were synthesized, and their biological activities were evaluated to determine their in vitro neuroprotective effects against Aβ25–35-induced damage in primary cortical neurons and against glutamate-induced neuronal injury in primary cerebellar granule neurons. The results indicated that all of the tested analogues displayed neuroprotective activity at 0.1 μM or 1 μM. These findings may provide new insights into the development of novel promising H3 receptor antagonists with potential neuroprotective activity.

The synthesis and characterization of a novel Rhodamine B [2]rotaxane is described. This species contains dibenzyl-24-crown-8 (DB24C8) as a wheel, which is threaded onto a sec-ammonium-containing axle. The axle has a Rhodamine B unit and a 2,2-diphenylethanamine unit as two bulky terminal stoppers to prevent unthreading.

In the conventional digital peak current (DPC) predictive controlled switching dc-dc converters, the duty ratio in each switching cycle is usually calculated and predicted based on the status of the previous switching cycles. Therefore at least one-switching-cycle time delay usually exists in such a predictive control technique, which significantly degrades the control performance of digitally controlled switching dc-dc converters. To eliminate this one-switching-cycle time delay and to improve the control performance, an improved digital peak current (IDPC) predictive control technique for switching dc-dc converters is then proposed and studied in this study. The control laws of DPC and IDPC control with different pulse width modulations are derived and their stabilities are analysed. A simple digital slope compensation method is proposed to eliminate the sub-harmonic oscillations of DPC and IDPC control laws. Steady-state and transient performances of DPC- and IDPC-controlled buck converters are investigated and compared by experimental results. The comparison studies between DPC and IDPC control show that transient performance of IDPC is much better than that of DPC.

A method for the two-step synthesis of magnetic composites with a γ-Fe2O3 core, silica inner layer and numerous gold nanoparticles supported on the surface of the silica (γ-Fe2O3/SiO2/Au) is described. First, thiol-functionalized γ-Fe2O3/SiO2 composites and gold colloids are prepared by modifying γ-Fe2O3/SiO2 composites with mercaptosilane and reduction of Au3+ to Au0 with citrate, respectively. Gold nanoparticles are then assembled on the surface of the thiol-functionalized γ-Fe2O3/SiO2 composites to form γFe2O3/SiO2/Au composites. The structure of the composite particles is confirmed by transmission electronic microscopy and powder X-ray diffraction. Immobilization studies with bovine serum albumin (BSA) demonstrate that the γ-Fe2O3/SiO2/Au composites can be used to immobilize BSA, making them useful for biomedical and biological applications.