Formation mechanisms of sub-micron pharmaceutical composite particles derived from far-and near-field Raman microscopy

Surface enhanced Raman spectroscopy(SERS) and confocal Raman microscopy are applied to investigate the structure and the molecular arrangement of sub-micron furosemide and polyvinylpyrrolidone(furosemide/PVP) particles produced by spray flash evaporation(SFE). Morphology, size and crystallinity of furosemide/PVP particles are analyzed by scanning electron microscopy(SEM) and X-ray powder diffraction(XRPD). Far-field Raman spectra and confocal far-field Raman maps of furosemide/PVP particles are interpreted based on the far-field Raman spectra of pure furosemide and PVP precursors.Confocal far-field Raman microscopy shows that furosemide/PVP particles feature an intermixture of furosemide and PVP molecules at the sub-micron scale. SERS and surface-enhanced confocal Raman microscopy(SECo RM) are performed on furosemide, PVP and furosemide/PVP composite particles sputtered with silver(40 nm). SERS and SECo RM maps reveal that furosemide/PVP particle surfaces mainly consist of PVP molecules. The combination of surface and bulk sensitive analyses reveal that furosemide/PVP sub-micron particles are formed by the agglomeration of primary furosemide nanocrystals embedded in a thin PVP matrix. Interestingly, both far-field Raman microscopy and SECo RM provide molecular information on a statistically-relevant amount of sub-micron particles in a single microscopic map;this combination is thus an effective and time-saving tool for investigating organic sub-micron composites.

Microstructure and Strength of Laser Welds of Sub-micron Particulate-reinforced Aluminum Matrix Composite Al_2O_(3p)/6061Al

The microstructure of laser welds of sub-micron particulate-reinforced aluminum matrix composite Al_2O_(3p)/6061Al and the weldability of the material were studied. Experimental results indicated that because of the huge specific surface area of the reinforcement, the interfacial reaction between the matrix and the reinforcement was re- strained intenslvely at elevated temperature and pulsed laser beam. The main factor affecting the weldability of the com- posite was the reinforcement segregation in the weld resulting from the push of the liquid/solid interface during the soli- dification of the molten pool. The laser pulse frequency directly affected the reinforcement segregation and the reinfor- cement distribution in the weld, so that the weldability of the composite could be improved by increasing the laser pulse frequency. On the basis of this, a satisfactory welded joint of sub-micron paniculate-reinforced aluminum matrix com- posite Al_2O_(3p)/6061Al was obtained by using appopriate welding parameters.

A novel solution-based self-assembly approach to preparing ultralong titanyl phthalocyanine sub-micron wires

Ultralong titanyl phthalocyanine （TiOPc） sub-micron wires have been synthesized by a novel solution-based self- assembly method. By using different solvents, changing the mass concentration and the solvent vapor pressure, the length and the shape of the wires can be adjusted. The mixed-phase properties of the TiOPc sub-micron wires were investigated by the ultraviolet-visible （UV-vis） absorption spectrum and X-ray diffraction. Organic transistors based on these wires were studied, which show the typical p-channel characteristics.

Effect of flow field distribution on the synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system

Scale-up synthesis of sub-micron ZSM-5 molecular sieve in a quasi-solid system was investigated. Compared with traditional hydrothermal synthesis, the synthesis in a quasi-solid system has the advantages of high yield, short crystallization time, low energy consumption as well as low emissions. However, the high solid content in the quasi-solid system can cause the mass and heat transfer problems and make scalable production difficult. In order to solve the problem, we have developed a method for the optimization of the mass and heat transfer. By this method one can vary the flow field in the reactor by changing the stirrer speed. Scale-up synthesis of the sub-micron ZSM-5 molecular sieve in a quasi-solid system was carried out in a 5 L reactor with double propeller-type agitators. The process was investigated with product characterization using X-ray diffraction （XRD） and scanning electron microscopy （SEM） and the flow field information was collected using laser Doppler velocimetry （LDV）. The results showed that the flow field patterns can be tuned by using different stirrer speeds, the morphology and size of assynthesized of ZSM-5 can be effectively controlled.

Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

Pattem imprinting in deep sub-micron static random access memories （SRAMs） during total dose irradiation is inves- tigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell＇s static noise margin （SNM） and the background data, and study the influence of irradiation on the probability density function of ASNM, which is the difference between two data sides＇ SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation （STI） oxide rather than from the gate oxide of the micron-device.

STUDY ON THE RELATION BETWEEN STRUCTURE AND HOT CARRIER EFFECT IMMUNITY FOR DEEP SUB-MICRON GROOVED GATE NMOSFET's

Grooved gate structure Metal-Oxide-Semiconductor (MOS) device is consideredas the most promising candidate used in deep and super-deep sub-micron region, for it cansuppress hot carrier effect and short channel effect deeply. Based on the hydrodynamic energytransport model, using two-dimensional device simulator Medici, the relation between structureparameters and hot carrier effect immunity for deep-sub-micron N-channel MOSFET's is studiedand compared with that of counterpart conventional planar device in this paper. The examinedstructure parameters include negative junction depth, concave corner and effective channel length.Simulation results show that grooved gate device can suppress hot carrier effect deeply even indeep sub-micron region. The studies also indicate that hot carrier effect is strongly influencedby the concave corner and channel length for grooved gate device. With the increase of concavecorner, the hot carrier effect in grooved gate MOSFET decreases sharply, and with the reducingof effective channel length, the hot carrier effect becomes large.

Δ<i>I_DDQ</i>Testing of a CMOS Digital-to-Analog Converter Considering Process Variation Effects

In this paper, we present the implementation of a built-in current sensor (BICS) which takes into account the increased background current of defect-free circuits and the effects of process variation on ΔIDDQ testing of CMOS data converters. A 12-bit digital-to-analog converter (DAC) is designed as the circuit under test (CUT). The BICS uses frequency as the output for fault detection in CUT. A fault is detected if it causes the output frequency to deviate more than ±10% from the reference frequency. The output frequencies of the BICS for various (MOSIS) model parameters are simulated to check for the effect of process variation on the frequency deviation. A set of eight faults simulating manufacturing defects in CMOS data converters are injected using fault-injection transistors and tested successfully.

Photoelectrochemical performance of a sub-micron structured film with poly(3-methylthiophene) (P3MT)-modified CdTe/ZnO shell-core sub-micron tube arrays

A sub-micron structured film with a poly(3-methylthiophene) (P3MT)-modified CdTe/ZnO shell-core sub-micron tube array has been prepared by a series of electrodeposition processes, and a semiconductor-sensitized solar cell based on this structure was also fabricated. Vertically oriented ZnO sub-micron tubes were obtained on an indium tin oxide (ITO) substrate, and then CdTe nanocrystals and a thin P3MT layer were electrodeposited sequentially onto the walls of the ZnO sub-micron tubes. A suitable thickness of CdTe and P3MT could improve the photovoltaic properties of the solar cell, which was attributed to the enhancement in the light absorption and the decrease in the recombination of photogenerated carriers. In addition, a p–n heterojunction formed between the interface of CdTe and P3MT played an important part in the efficient separation and fast transport of photogenerated carriers in the sub-micron structure. A power conversion efficiency of 1.20% was obtained with this type of solar cell.

Strontium-substituted sub-micron bioactive glasses inhibit ostoclastogenesis through suppression of RANKL-induced signaling pathway

Strontium-substituted bioactive glass(Sr-BG)has shown superior performance in bone regeneration.Sr-BG-induced osteogenesis has been extensively studied;however,Sr-BG-mediated osteoclastogenesis and the underlying molecular mechanism remain unclear.It is recognized that the balance of osteogenesis and osteoclastogenesis is closely related to bone repair,and the receptor activators of nuclear factor kappaB ligand(RANKL)signaling pathway plays a key role of in the regulation of osteoclastogenesis.Herein,we studied the potential impact and underling mechanism of strontium-substituted sub-micron bioactive glass(Sr-SBG)on RANKL-induced osteoclast activation and differentiation in vitro.As expected,Sr-SBG inhibited RANKL-mediated osteoclastogenesis significantly with the experimental performance of decreased mature osteoclasts formation and downregulation of osteoclastogenesis-related gene expression.Furthermore,it was found that Sr-SBG might suppress osteoclastogenesis by the combined effect of strontium and silicon released through inhibition of RANKL-induced activation of p38 and NF-κB pathway.These results elaborated the effect of Sr-SBG-based materials on osteoclastogenesis through RANKLinduced downstream pathway and might represent a significant guidance for designing better bone repair materials.

Surface plasmon interference pattern on the surface of a silver-clad planar waveguide as a sub-micron lithography tool

A new sub-micron photolithography tool has been realized by utilizing the interference of surface plasmon waves(SPWs) on the near surface of a silver(Ag)-clad ultraviolet(UV) planar waveguide.A laser beam with a wavelength of 325 nm was incident into the waveguide core,and suffered a series of total internal reflections on the interfaces between the waveguide core and the cladding layers.The incident light and the reflected light induced two beams of SPWs traveling in contrary directions,which interfered with each other and formed a standing wave as a sub-micron photolithography tool.A near-field scanning optical microscope(NSOM) was employed to measure the intensity distribution of the stationary wave field of the near surface of the Ag layer of the waveguide,anastomosed with theoretical values acquired by use of finite difference time domain(FDTD) simulations.And with this sub-micron photolithography tool a SMG with a period of 79.3 nm,in good agreement with the theoretical value of 80.1 nm,was inscribed on the surface of a self-processing hybrid SiO2/ZrO2 solgel film for the first time.

Low-Temperature and Surfactant-Free Synthesis of Mesoporous TiO_2 Sub-Micron Spheres for Efficient Dye-Sensitized Solar Cells

Dye-sensitized solar cells （DSSCs） are one of the most promising next-generation solar cells due to their advantages over other counterparts. The photoanode of DSSCs has a great effect on the photovoltaic per- formance. Traditional photoanode includes a bottom nanoparticle layer and an upper scattering layer for better light capture in longer wavelength. Mesoporous nanostructures with size comparable to the wavelength of visible light are considered to be excellent light scattering centers by providing extra places for dye loading. Developing a green synthetic method is of great importance. Herein we report a facile and surfactant-free synthesis of mesoporous futile TiO2 submicrometer-sized spheres at temperature as low as 70 ℃. DSSCs based on photoanodes with an upper scattering layer composed of as-obtained mesoporous spheres on nanoparticle dense layer demonstrate an 18.0% improvement of power conver- sion efficiency. This simple approach may offer an energy-efficient and environmentally friendly alternative for DSSCs fabrication.

Characterization analysis of UDSM LVTSCR under TLP stress

The characteristics of a low-voltage triggering silicon-controlled rectifier （LVTSCR） under a transmission line pulse （TLP） and the characteristics of high frequency are analyzed. The research results show that the anode series resistance has a significant effect on the key points of the snapback curve. The device characteristics can fit the requirements of a electrostatic discharge （ESD） design window by adjusting the anode series resistance. Furthermore, the set-up time of the ESD has an influence on the turn-on voltage of the LVTSCR. A steep rising edge will cause the turn-on voltage to increase. The parasitic capacitance of the device for different voltage biases and frequencies determines the capacitive impedance, and its accuracy calculation is very important to the ESD design of high frequency circuits. Our research results provide a theoretical basis for the design of an ultra-deep sub-micron （UDSM） LVTSCR structure under ESD stress and the improvement of TLP test technology.

Gate leakage current reduction in IP3 SRAM cells at 45 nm CMOS technology for multimedia applications

We have presented an analysis of the gate leakage current of the IP3 static random access memory （SRAM） cell structure when the cell is in idle mode（performs no data read/write operations） and active mode （performs data read/write operations）,along with the requirements for the overall standby leakage power,active write and read powers.A comparison has been drawn with existing SRAM cell structures,the conventional 6T,PP, P4 and P3 cells.At the supply voltage,V_（DD） = 0.8 V,a reduction of 98%,99%,92%and 94%is observed in the gate leakage current in comparison with the 6T,PP,P4 and P3 SRAM cells,respectively,while at V_（DD） = 0.7 V,it is 97%,98%,87%and 84%.A significant reduction is also observed in the overall standby leakage power by 56%〉, the active write power by 44%and the active read power by 99%,compared with the conventional 6T SRAM cell at V_（DD）= 0.8 V,with no loss in cell stability and performance with a small area penalty.The simulation environment used for this work is 45 nm deep sub-micron complementary metal oxide semiconductor（CMOS） technology,t_（ox） = 2.4 nm,K_（thn） = 0.22 V,K_（thp） = 0.224 V,V_（DD） = 0.7 V and 0.8 V,at T = 300 K.