\u3ci\u3eR\u3c/i\u3e-Curve Behavior of \u3ci\u3eIn Situ\u3c/i\u3e Toughened alpha-SiAlON Ceramics

R-curves of single-phase Y- and Ca-containing α-SiAlON ceramics have been measured. They range from flat ones for fine-grain ceramics to pronounced rising ones when large elongated grains are present. The highest toughness measured reached 11.5 MPa∙m1/2 over a crack extension of about 1000 μm

Effect of Seeding on the Microstructure and Mechanical Properties of alpha-SiAlON: I, Y-SiAlON

The effect of seeding on the microstructure and mechanical properties of single-phase Y-α-SiAlON ceramics with elongated grains has been studied. Seeds of the intended α-SiAlON compositions but with different size, shape, and number of grains have been compared for their effects. The microstructure, resistance (R-curve) behavior, and Weibull modulus are strongly correlated to the number density of the seeds. The highest fracture toughness reached is ~12 MPa∙m1/2 and can be obtained with as little as 1% seeding. The thermodynamic stability of seeds has been examined and is attributed to their chemical composition

Synthesis of alpha-SiAlON Seed Crystals

Single-phase seed crystals of Ca- and Y-α-SiAlONs have been synthesized for tailoring microstructure of α-SiAlON ceramics. The influence of composition, sintering temperature, and nitrogen pressure on the size and morphology of seeds has been explored. Guidelines for α-SiAlON seed preparation and morphology control are provided

Effect of Long-Range Interactions in the Conserved Kardar-Parisi-Zhang Equation

The conserved Kardar-Parisi-Zhang equation in the presence of long-range nonlinear interactions is studied by the dynamic renormalization group method. The long-range effect produces new fixed points with continuously varying exponents and gives distinct phase transitions, depending on both the long-range interaction strength and the substrate dimension $d$. The long-range interaction makes the surface width less rough than that of the short-range interaction. In particular, the surface becomes a smooth one with a negative roughness exponent at the physical dimension d=2.Comment: 4 pages(LaTex), 1 figure(Postscript

Effect of gauge boson mass on the phase structure of QED3_{3}

Dynamical chiral symmetry breaking (DCSB) in QED$_{3}$ with finite gauge boson mass is studied in the framework of the rainbow approximation of Dyson-Schwinger equations. By adopting a simple gauge boson propagator ansatz at finite temperature, we first numerically solve the Dyson-Schwinger equation for the fermion self-energy to determine the chiral phase diagram of QED$_3$ with finite gauge boson mass at finite chemical potential and finite temperature, then we study the effect of the finite gauge mass on the phase diagram of QED$_3$. It is found that the gauge boson mass $m_{a}$ suppresses the occurrence of DCSB. The area of the region in the chiral phase diagram corresponding to DCSB phase decreases as the gauge boson mass $m_{a}$ increases. In particular, chiral symmetry gets restored when $m_{a}$ is above a certain critical value. In this paper, we use DCSB to describe the antiferromagnetic order and use the gauge boson mass to describe the superconducting order. Our results give qualitatively a physical picture on the competition and coexistence between antiferromagnetic order and superconducting orders in high temperature cuprate superconductors.Comment: 10 pages, 2 figure

First-Generation College Students' Information Seeking: Their Personality Traits and Source Use Behavior in Coursework-Related Context

ABSTRACT This study examines first-generation college (FGC) students' information seeking in coursework-related situations and the relationship between personality and source use behavior. A web survey was used to collect data. Four-hundred and fifty FGC students participated in the study. A two-step cluster analysis was used to identify three subgroups of personality profiles from the sample. Multivariate analyses of variance (MANOVA) and multiple regression analyses were used to analyze the data. Results show that extroverts used human sources more frequently across all coursework-related situations and tended to consult peers in the same course in their information seeking processes. Conscientious students tended to consult professors and advisors in their coursework-related information seeking processes. Calm and open-minded extroverts consulted human sources (both experts and nonexperts) more often and used more diverse sources than nervous and close-minded introverts. The study enriches FGC student literature in information behavior and further incorporates personality traits as predictors of information use. The study also implies that universities and academic libraries should support orientation programs and organizations that can help FGC students, especially introverts, develop their social networks and have an easy transition into college

Generation of angular-momentum-dominated electron beams from a photoinjector

Various projects under study require an angular-momentum-dominated electron beam generated by a photoinjector. Some of the proposals directly use the angular-momentum-dominated beams (e.g. electron cooling of heavy ions), while others require the beam to be transformed into a flat beam (e.g. possible electron injectors for light sources and linear colliders). In this paper, we report our experimental study of an angular-momentum-dominated beam produced in a photoinjector, addressing the dependencies of angular momentum on initial conditions. We also briefly discuss the removal of angular momentum. The results of the experiment, carried out at the Fermilab/NICADD Photoinjector Laboratory, are found to be in good agreement with theoretical and numerical models.Comment: 8 pages, 7 figures, submitted to Phys. Rev. ST Accel. Beam

High Fidelity Tape Transfer Printing Based On Chemically Induced Adhesive Strength Modulation

Transfer printing, a two-step process (i.e. picking up and printing) for heterogeneous integration, has been widely exploited for the fabrication of functional electronics system. To ensure a reliable process, strong adhesion for picking up and weak or no adhesion for printing are required. However, it is challenging to meet the requirements of switchable stamp adhesion. Here we introduce a simple, high fidelity process, namely tape transfer printing(TTP), enabled by chemically induced dramatic modulation in tape adhesive strength. We describe the working mechanism of the adhesion modulation that governs this process and demonstrate the method by high fidelity tape transfer printing several types of materials and devices, including Si pellets arrays, photodetector arrays, and electromyography (EMG) sensors, from their preparation substrates to various alien substrates. High fidelity tape transfer printing of components onto curvilinear surfaces is also illustrated