Novel microcontacts in microwave chip carriers developed by UV-liga process part II

This paper presents the design and development of novel type microcontacts in monolithic microwave integrated circuit (MMIC) chip-carriers to printed circuit board (PCB) assembly. Several new concepts of microcontacts for packaging solutions of microwave and millimeter-wave MMIC are depicted. Simulation and vector network analyzer (VNA) measurement results for these microcontact transitions are discussed. The results show that the electrical parameters are highly dependent on the transition dimensions and substrate features. These contacts are based on male stud (bump) and female (ring) concept. When mating each other, there are clips effect and self-alignment features. Special attention is paid to the shape of the microcontacts in order to facilitate assembly and strengthen the connection. Equivalent electrical circuit is proposed for PSPICE simulation of the dc contact resistance. Finally, the article discusses the technological implementation of the proposed new microcontact stud-ring through low-cost ultraviolet electroplating, lithography, and molding (UV-LIGA) process and the regime influence on the shape, geometry, and mating capabilities. Results from mechanical pull and adhesion tests are also discussed.     

Neutron yields from 1 GeV/nucleon U ion beams on Fe target

Yields of neutrons produced by a ²³⁸U ion beam of 1 GeV/nucleon kinetic energy impinging on a thick Fe target were measured resulting in distributions differential in neutron angle (0° < _n < 20°) and in kinetic energy (T_n > 50 MeV). The data serve in radiation protection planning for next-generation rare-isotope beam facilities. The experimental data are contrasted with predictions from transport codes as currently used in radiation shield design studies.     

Developing a Mathematical Model of Intracellular Calcium Dynamics for Evaluating Combined Anticancer Effects of Afatinib and RP4010 in Esophageal Cancer

Targeting dysregulated Ca²⁺ signaling in cancer cells is an emerging chemotherapy approach. We previously reported that store-operated Ca²⁺ entry (SOCE) blockers, such as RP4010, are promising antitumor drugs for esophageal cancer. As a tyrosine kinase inhibitor (TKI), afatinib received FDA approval to be used in targeted therapy for patients with EGFR mutation-positive cancers. While preclinical studies and clinical trials have shown that afatinib has benefits for esophageal cancer patients, it is not known whether a combination of afatinib and RP4010 could achieve better anticancer effects. Since TKI can alter intracellular Ca²⁺ dynamics through EGFR/phospholipase C-γ pathway, in this study, we evaluated the inhibitory effect of afatinib and RP4010 on intracellular Ca²⁺ oscillations in KYSE-150, a human esophageal squamous cell carcinoma cell line, using both experimental and mathematical simulations. Our mathematical simulation of Ca²⁺ oscillations could fit well with experimental data responding to afatinib or RP4010, both separately or in combination. Guided by simulation, we were able to identify a proper ratio of afatinib and RP4010 for combined treatment, and such a combination presented synergistic anticancer-effect evidence by experimental measurement of intracellular Ca²⁺ and cell proliferation. This intracellular Ca²⁺ dynamic-based mathematical simulation approach could be useful for a rapid and cost-effective evaluation of combined targeting therapy drugs.     

Formal analysis of piecewise affine systems through formula-guided refinement

We present a computational framework for identifying a set of initial states from which all trajectories of a piecewise affine (PWA) system with additive uncertainty satisfy a linear temporal logic (LTL) formula over a set of linear predicates in its state variables. Our approach is based on the construction and refinement of finite abstractions of infinite systems. We derive conditions guaranteeing the equivalence of an infinite system and its finite abstraction with respect to a specific LTL formula and propose a method for the construction of such formula-equivalent abstractions. While provably correct, the overall method is conservative and expensive. A tool for PWA systems implementing the proposed procedure using polyhedral operations and analysis of finite graphs is made available. Examples illustrating the analysis of PWA models of gene networks are included.     

Numerical simulation of multi-species biofilms in porous media for different kinetics

There are bacteria that can form strong biofilms in porous media. These biofilms can be used as biobarriers to restrict the flow of pollutants. For certain contaminants, a second species of bacteria that can actually react with the contaminants can be added to the biobarrier to actually degrade the pollutants. We propose some mathematical models for the formation of these reacting biobarriers under different hypotheses, and numerically solve the resulting equations for the flow, transport and reactions. Qualitative comparisons with some experimental results are also given.