抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Diamond-like carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This review will describe the deposition methods, deposition mechanisms, characterisation methods, electronic structure, gap states, defects, doping, luminescence, field emission, mechanical properties and some applications of DLCs. The films have widespread applications as protective coatings in areas, such as magnetic storage disks, optical windows and micro-electromechanical devices (MEMs).

/pdf/diamond-like-amorphous-carbon-3pczopr0z7.pdf

Diamond-like amorphous carbon

Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces between materials become increasingly important on small length scales. The thermal conductance of many solid–solid interfaces have been studied experimentally but the range of observed interface properties is much smaller than predicted by simple theory. Classical molecular dynamics simulations are emerging as a powerful tool for calculations of thermal conductance and phonon scattering, and may provide for a lively interplay of experiment and theory in the near term. Fundamental issues remain concerning the correct definitions of temperature in nonequilibrium nanoscale systems. Modern Si microelectronics are now firmly in the nanoscale regime—experiments have demonstrated that the close proximity of interfaces and the extremely small volume of heat dissipation strongly modifies thermal transport, thereby aggravating problems of thermal management. Microelectronic devices are too large to yield to atomic-level simulation in the foreseeable future and, therefore, calculations of thermal transport must rely on solutions of the Boltzmann transport equation; microscopic phonon scattering rates needed for predictive models are, even for Si, poorly known. Low-dimensional nanostructures, such as carbon nanotubes, are predicted to have novel transport properties; the first quantitative experiments of the thermal conductivity of nanotubes have recently been achieved using microfabricated measurement systems. Nanoscale porosity decreases the permittivity of amorphous dielectrics but porosity also strongly decreases the thermal conductivity. The promise of improved thermoelectric materials and problems of thermal management of optoelectronic devices have stimulated extensive studies of semiconductor superlattices; agreement between experiment and theory is generally poor. Advances in measurement methods, e.g., the 3ω method, time-domain thermoreflectance, sources of coherent phonons, microfabricated test structures, and the scanning thermal microscope, are enabling new capabilities for nanoscale thermal metrology.

/pdf/nanoscale-thermal-transport-1frv881kzm.pdf

Nanoscale thermal transport

Nature de la liaison etudiee par calculs chimiques de quantum, liaison delocalisee resultant de la formation d'un complexe de transfert de charges entre le metal et le polyimide

Delocalized bonding at the metal-polymer interface

Electromigration lifetime and failure mechanism have been investigated for Cu/SiLK/spl trade/ interconnects. The activation energies of Cu/SiLK and Cu/oxide were found to be 0.98 eV and 0.81 eV respectively. The activation energy in the range of 0.8 to 1.0 ev suggests a similar mass transport mechanism that can be attributed to interfacial diffusion. The average lifetime of Cu/SiLK was found to be shorter than that of Cu/oxide at test temperatures. The threshold critical length product of Cu/SiLK structures was determined to be about 1/3 of that of Cu/oxide structures. Failure analysis by FIB revealed a distinct failure mode due to lateral Cu extrusion at the low k/oxide etch stop interface. These results together with the increase observed in Joule heating and thermal resistance show that the thermomechanical properties play an important role in controlling the EM reliability of the low k interconnects. Results of this study suggest that the degradation in thermomechanical properties, in particular interfacial adhesion, reduces the back-flow stress, leading to faster mass transport, shorter EM lifetime and Cu extrusion at the anode in the SiLK structures.

Electromigration study of Cu/low k dual-damascene interconnects

Thermally induced stresses play an important role in controlling the structural reliability of flip-chip packages. As the demand for increased performance continues to shrink solder bump pitch and size, it becomes increasingly difficult to experimentally determine thermally induced displacements and strains within these packages. To address this issue, we have developed a high-resolution phase-shifting moire interferometry system to map thermally induced displacements and strains within underfilled flip-chip packages with a resolution up to 16 times greater than conventional moire interferometry. This technique has the capability to map displacement fields with 26 nm resolution, making it possible to accurately determine displacements and strains within features normally contained within one moire interference fringe. This system was demonstrated using a thermally loaded underfilled flip-chip package with 250 /spl mu/m solder bump pitch. Displacement contour maps with 26 nm resolution were obtained to demonstrate the capability to measure thermal displacements within features as small as 30 /spl mu/m. A second flip-chip package was analyzed to extract stress-intensity factors. A quantitative analysis was carried out at the die corner using experimental data and compared to finite element analysis results. A strain singularity analysis was also carried out. It was found that the experimental strains are higher and the strain singularity is lower than the finite element results.

Analysis of flip-chip packages using high resolution moire interferometry

The step-and-flash imprint lithography process requires the clean separation of a quartz template from a polymer, and the force required to create this separation must be minimized to prevent the generation of defects. Fluorinated surfactant additives to the imprint fluid address this problem by migrating to the template-polymer interface and forming a local layer with ideal properties for adhesive fracture. Tensile and four-point bend fracture experiments show that surfactants lower the modulus of the imprint polymer and decrease the fracture energy. The fracture energy is further decreased by using a nonreactive, liquid surfactant versus a surfactant that reacts with the polymer matrix. Angle-resolved X-ray photoelectron spectroscopy results indicate that surfactant migration is more effective with a fluorinated surface treatment compared to an untreated quartz surface. This result shows that the use of fluorinated surfactants must be accompanied by a surface treatment that produces a similar energy or polarity to induce migration and lower the adhesive strength.

Role of surfactants in adhesion reduction for step and flash imprint lithography

The effect of substrate temperature Ts during evaporation on the microstructure of Pd2Si thin films on (111) Si formed by evaporation followed by subsequent higher‐temperature anneal has been investigated by transmission electron microscopy. For Ts of 20 and 100 °C, the Pd2Si grows epitaxially on the substrate. For a Ts of 200 °C the Pd2Si is polycrystalline and grains are uniaxially textured about the [001] axis and there are pinholes in the film. For a Ts of 300 °C, the microstructure of Pd2Si is spongy and grains are much less oriented.

Paul S. Ho

Papers

Delocalized bonding at the metal-polymer interface

Electromigration study of Cu/low k dual-damascene interconnects

Analysis of flip-chip packages using high resolution moire interferometry

Role of surfactants in adhesion reduction for step and flash imprint lithography

Effect of substrate temperature on the microstructure of thin‐film silicide