There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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

Abstract The backbones of biodegradable and bioderived polymers often contain chemical bonds, such as ester and amide that are susceptible to hydrolysis. Here, we show that hydrolysis causes a transition from ductile to brittle fracture in poly(lactic acid) (PLA). Submerged in an aqueous solution and bearing a load, a sample with a precrack undergoes extensive plastic deformation when the crack grows fast, but negligible plastic deformation when the crack grows slowly. In the former, the ductile fracture creates rough and porous crack surfaces, indicating that polymer chains slip before scission. In the latter, the brittle fracture creates flat crack surfaces, indicating that polymer chains slip negligibly before scission. Furthermore, at a low load and over a broad range of pH, the velocity of a crack in PLA correlates with the rate of hydrolysis of lactic acid oligomers. Taken together, these observations demonstrate that PLA suffers hydrolytic embrittlement. The phenomenon should be taken into account in the design of—and with—biodegradable and bioderived polymers. Impact statement In thermoplastics of high molecular weights, repeat units form long polymer chains by chemical bonds, and the long polymer chains form solids by physical interactions. Between neighboring repeat units, the chemical bonds are commonly much stronger than the physical interactions. Polymer chains slip extensively before scission in ductile fracture, but slip negligibly before scission in brittle fracture. In biodegradable and bioderived thermoplastics, repeat units often link by chemical bonds susceptible to hydrolysis. Here, we show that hydrolysis embrittles a leading bioderived thermoplastic, poly(lactic acid). Even a small load exposes a crack tip to water molecules from the environment, hydrolyzing ester bonds and breaking chains with negligible chain slip. The material has a toughness above 10^4 J/m^2. However, submerged in an aqueous solution, the material can grow a crack at an energy release rate as low as 1 J/m^2. Hydrolytic embrittlement should be investigated for biodegradable and bioderived polymers under development for health care and sustainability. Graphical abstract

Hydrolysis embrittles poly(lactic acid)

This paper will focus on reliability study of interconnect structure for two areas. The first area is reliability of interconnect structure in thermal cycling test. Major work includes the fundamental study of ratcheting for passivation cracking. By combination with the upper limit of stress intensity factor for a finite crack in the passivation and the ratcheting failure mechanism, the life of passivation in thermal cycling can be obtained in terms of the lower bound of critical number of cycles of the crack initiation. The passivation crack criterion is established to identify the failure modes: no cracking and delayed cracking. Another area is the reliability of bond paid over active (BPOA) with copper bond pads. Major work includes stress analysis of the dielectric layer under probing with different parameters such as the thickness of the copper bond pad, dielectric, metallization and the passivation under different probing loads. The elastic plastic model in copper bond pad and metal lines are introduced. Finally comparison of the results between copper bond pad and aluminum bond pad will be presented

Reliability Study of Interconnect Structures in IC Packages

Mechanics and chemical thermodynamics of a temperature-sensitive hydrogel

An approach of integrating multiple film bulk acoustic resonators (FBAR) with different frequencies is presented. Conventional FBAR structures were modified by adding a patterned tuning layer on top of Metal/AlN/Metal film stack. By controlling the dimensions of the periodic tuning pattern, resonance frequencies can be modulated due to mass loading effects. As a result, multiple-frequency resonators can be lithographically defined by a single deposition/patterning processing sequence. From finite element analysis, it was found that the pitch of the periodic tuning layer pattern had to be smaller than the characteristic dimension of the resonator, the membrane thickness, to avoid distortion of the resonance peak and to maintain resonator performance. This approach may lead to a viable solution for future integrated multi-mode radio RF front end.

A Novel Approach to Integrate Multiple Film Bulk Acoustic Resonators (FBAR) with Different Frequencies in a Single Chip

This paper outlines the use of the Principle of Virtual Motion and the Galerkin approximation to analyze surface diffusion phenomena. Various ideas are illustrated with an analysis of the evolution of a fiber of bamboo-like grain structure.

Zhigang Suo

Papers

Hydrolysis embrittles poly(lactic acid)

Reliability Study of Interconnect Structures in IC Packages

Mechanics and chemical thermodynamics of a temperature-sensitive hydrogel

A Novel Approach to Integrate Multiple Film Bulk Acoustic Resonators (FBAR) with Different Frequencies in a Single Chip

Using Principle of Virtual Motion and Galerkin Approximation to Analyze Surface Diffusion