Simulation and experimental study of a K-band extended interaction oscillator for microwave processing systems.

High-power microwave sources have been widely applied for material processing in scientific research and manufacturing. The development of stable, high-frequency, high-power microwave sources is essential for achieving efficient microwave processing. This study proposes using a square doubly reentrant coupled-cavity as the slow-wave resonant structure in a K-band extended interaction oscillator (EIO). This design allows for ease of fabrication and high-power capability. The EIO is designed to operate in single 0-mode. The simulation results show that the competing π/5-mode can be effectively suppressed by properly choosing the width and location of the output coupler. The simulation and experiments successfully demonstrate stable, single-mode, tunable, high-performance operation of the EIO. The experimental measurements show a maximum output power of 1.776 kW (18.56% electronic efficiency), and a wave frequency of 24.324 GHz at a beam voltage of 17.4 kV and beam current of 550 mA. The EIO microwave source is suitable for interdisciplinary applications that require higher heating rates and greater uniformity.

[Expression of ALK protein in 7 371 pulmonary adenocarcinoma samples, with analysis of clinicopathologic features].

OBJECTIVE: To study the expression of ALK protein in pulmonary adenocarcinoma as detected by Ventana immunohistochemistry, with correlation of clinicopathologic features. METHODS: Immunohistochemical study for ALK protein using Ventana ALK (D5F3) kit was carried in 7 371 pulmonary adenocarcinoma samples. The clinicopathologic features were subsequently analyzed. RESULTS: ALK fusion protein was detected in 446 of the 7 371 lung adenocarcinoma samples studied (6.05%). The ALK positivity rate in small biopsy samples was higher than that in surgical specimens [9.02% (153/1 696) versus 5.16% (293/5 675); P<0.01]. ALK fusion protein expression correlated with patient age, sample type and smoking history. ALK positivity rate in each age group increased with younger patient age. ALK positivity rate was 45.45% (10/22) in patients younger than 30 years old. The positivity rate of ALK fusion protein in adenocarcinoma in-situ, minimally invasive adenocarcinoma and invasive adenocarcinoma was 0, 0.48% (2/418) and 5.63% (291/5 165), respectively. The differences of ALK positivity rate amongst different subtypes had statistical significance (P<0.01). Invasive mucinous adenocarcinoma had highest ALK positivity rate, followed by invasive adenocarcinoma with predominantly solid pattern. CONCLUSIONS: ALK fusion protein is more often found in young patients with pulmonary adenocarcinoma, especially in those younger than 30 years old. ALK fusion protein is rarely expressed in early-stage pulmonary adenocarcinoma. Invasive mucinous adenocarcinoma and invasive adenocarcinoma with solid pattern have higher ALK positivity rate than other adenocarcinoma subtypes.

A microwave applicator for uniform irradiation by circularly polarized waves in an anechoic chamber.

Microwave applicators are widely employed for materials heating in scientific research and industrial applications, such as food processing, wood drying, ceramic sintering, chemical synthesis, waste treatment, and insect control. For the majority of microwave applicators, materials are heated in the standing waves of a resonant cavity, which can be highly efficient in energy consumption, but often lacks the field uniformity and controllability required for a scientific study. Here, we report a microwave applicator for rapid heating of small samples by highly uniform irradiation. It features an anechoic chamber, a 24-GHz microwave source, and a linear-to-circular polarization converter. With a rather low energy efficiency, such an applicator functions mainly as a research tool. This paper discusses the significance of its special features and describes the structure, in situ diagnostic tools, calculated and measured field patterns, and a preliminary heating test of the overall system.

Comparison of NMOSFET and PMOSFET devices that combine CESL stressor and SiGe channel.

Strained-Si technology could enhance the carrier mobility and improve the device performance. Contact-etch-stop-layer (CESL) structure with different stress and SiGe channel was fabricated with 90-nm technology. The electrical properties of N and PMOSFET devices combining CESL and SiGe channel were investigated. The short channel effects (SCE), such as drain-induced barrier lowering (DIBL), were also studied. Moreover, the stress contour in the SiGe channel has been simulated with TCAD to understand the relationship between stress distribution and device performance for different CESL structures. It is observed that the stress in the channel region was independent of the type of N or PMOSFET devices, but it was dependent on the CESL type and channel length. Based on the experimental and simulation results, it is confirmed that the device performance is associated with the stress in the channel, and the approach of CESL stressor and SiGe channel is shown to effectively improve the mobility of NMOSFETs and PMOSFETs.

Formation of chiral morphologies through selective binding of amino acids to calcite surface steps.

Many living organisms contain biominerals and composites with finely tuned properties, reflecting a remarkable level of control over the nucleation, growth and shape of the constituent crystals. Peptides and proteins play an important role in achieving this control. But the general view that organic molecules affect mineralization through stereochemical recognition, where geometrical and chemical constraints dictate their binding to a mineral, seems difficult to reconcile with a mechanistic understanding, where crystallization is controlled by thermodynamic and kinetic factors. Indeed, traditional crystal growth models emphasize the inhibiting effect of so-called 'modifiers' on surface-step growth, rather than stereochemical matching to newly expressed crystal facets. Here we report in situ atomic force microscope observations and molecular modelling studies of calcite growth in the presence of chiral amino acids that reconcile these two seemingly divergent views. We find that enantiomer-specific binding of the amino acids to those surface-step edges that offer the best geometric and chemical fit changes the step-edge free energies, which in turn results in macroscopic crystal shape modifications. Our results emphasize that the mechanism underlying crystal modification through organic molecules is best understood by considering both stereochemical recognition and the effects of binding on the interfacial energies of the growing crystal.

In vitro degradation and dissolution behaviours of microspheres prepared by three low molecular weight polyesters.

Three low-molecular weight polyesters, poly(L-lactic acid) (PLA), copoly(lactic acid/glycolic acid) (PLGA) and poly(delta-valerolactone) (PV), were used to prepare water-soluble sodium diclofenac-loaded microspheres by using the oil-in-oil (o/o) emulsification-solvent evaporation method. Their micromeritic and physicochemical properties, and degradation and dissolution behaviours were determined in vitro. The results indicate that high encapsulation efficiency and better monodispersity might be achieved by the o/o emulsification-solvent evaporation method, depending on the amount of drug loading used. The slower evaporation of organic solvent from the system during microencapsulation seemed to modify the crystallinity of drug and polyester in the microspheres, determined by powder x-ray diffractometry and differential scanning calorimetry. The in vitro degradation rate of all the microspheres in pH7.4 phosphate buffer solution showed first-order kinetics and ranked in the order of PLGA > PLA > PV microspheres. Furthermore, the first-order release rate was also found in all the microspheres after an initial drug burst and ranked in the order of PLGA> PLA > PV microspheres, too. The relationship between degradation and dissolution behaviours of these microspheres is discussed.

Protective colloids and polylactic acid co-affecting the polymorphic crystal forms and crystallinity of indomethacin encapsulated in microspheres.

The co-effect of protective colloids and polylactic acid (PLA) on the polymorphic crystal forms and crystallinity of indomethacin (IMC) in IMC-loaded PLA microspheres was investigated with differential scanning calorimetry, infrared spectroscopy and x-ray diffractometry, to evaluate the polymorphic crystal forms and crystallinity of IMC encapsulated in PLA microspheres. The surfactant, sodium dodecyl sulphate (SDS), was also used as a dispersing agent. The results indicate that the polymorphism and crystallinity of IMC encapsulated in IMC-loaded PLA microspheres was dependent on the type of protective colloid and PLA used. The amorphous state and alpha-form of IMC were found in the IMC-loaded PLA microspheres prepared using polysaccharide (pectin or beta-cyclodextrin) as a protective colloid or SDS as a dispersing agent. However, the amorphous and methylene chloride solvate of IMC seemed to exist in the IMC-loaded PLA microspheres prepared with the proteins (gelatin or albumin), synthetic cellulose derivative (methyl cellulose or hydroxylpropyl methylcellulose) or the synthetic nonionic polymer (polyvinyl alcohol, polyvinyl pyrrolidone or biosoluble polymer) as a protective colloid. PLA was found to express a certain crystallinity in microspheres and not be affected by the protective colloids, but it played a more important role in influencing the crystallization of IMC during microencapsulation than the protective colloids. No interaction occurred in the physical mixture of IMC and PLA, nor in the IMC-loaded PLA microspheres.

Functionality of protective colloids affecting the formation, size uniformity and morphology of drug-free polylactic acid microspheres.

Drug-free polylactic acid (PLA) microspheres were prepared by an emulsification-solvent evaporation technique using different types of protective colloids. The influence of five types of hydrophilic prolymers (polysaccharides, proteins, synthetic cellulose derivatives, synthetic nonionic polymers and surfactants) on the formation, size uniformity and morphology of PLA microspheres was investigated. Four characteristic functions (surface activity, viscosity, electric charge and interfacial film formation) of the hydrophilic polymer aqueous solutions were used to evaluate the efficacy of these protective colloids used. The results indicate that these four functions were the key parameters to achieve the formation of PLA microspheres. The best protective colloid should have high surface activity, optimum viscosity, adequate electric charge, and form an interfacial film to give a higher recovery, better size uniformity and smoother topography of the PLA microspheres.