Apparatus for Precise Indium-Bump Bonding of Microchips

An improved apparatus has been designed and built for use in precise positioning and pressing of a microchip onto a substrate (which could, optionally, be another microchip) for the purpose of indium-bump bonding. The apparatus (see figure) includes the following: A stereomicroscope, A stage for precise positioning of the microchip in rotation angle (theta) about the nominally vertical pressing axis and in translation along two nominally horizontal coordinate axes (x and y), and An actuator system that causes a bonding tip to press the microchip against the substrate with a precisely controlled force. In operation, the microscope and the stage are used to position the microchip under the bonding tip and to align the indium bumps on the chip and the substrate, then the actuator system is used to apply a prescribed bonding force for a prescribed time. The improved apparatus supplants a partly similar prior apparatus that operated with less precision and repeatability, producing inconsistent and unreliable bonds. Results of the use of the prior apparatus included broken microchips, uneven bonds, and bonds characterized, variously, by overcompression or undercompression. In that apparatus, the bonding force was generated and controlled by use of a micrometer head positioned over the center of a spring-loaded scale, and the force was applied to the microchip via the scale, which was equipped for digital readout of the force. The inconsistency of results was attributed to the following causes: It was not possible to control the bonding force with sufficient precision or repeatability. Particularly troublesome was the inability to control the force at levels less than the weight of 150 g. Excessive compliance in the spring-loaded scale, combined with deviations from parallelarity of the substrate and bonding-tip surfaces, gave rise to nonuniformity in the pressure applied to the microchip, thereby generating excessive stresses and deformations in the microchip. In the improved apparatus, the bonding tip and the components that hold the substrate and the microchip are more rigid and precise than in the prior apparatus, so as to ensure less deviation from parallelarity of the bonding-tip and substrate surfaces, thereby ensuring more nearly uniform distribution of bonding force over the area of the microchip. The bonding force is now applied through, and measured by, a load cell that makes it possible to exert finer control over the force. The force can be set at any value between 0 and the weight of 800 g in increments of 0.2 g

Modeling and Inspection Applications of a Coastal Distributed Autonomous Sensor Network

Real time in-situ measurements are essential for monitoring and understanding physical and biochemical changes within ocean environments. Phenomena of interest usually display spatial and temporal dynamics that span different scales. As a result, a combination of different vehicles, sensors, and advanced control algorithms are required in oceanographic monitoring systems. In this study our group presents the design of a distributed heterogeneous autonomous sensor network that combines underwater, surface, and aerial robotic vehicles along with advanced sensor payloads, planning algorithms and learning principles to successfully operate across the scales and constraints found in coastal environments. Examples where the robotic sensor network is used to localize algal blooms and collect modeling data in the coastal regions of the island nation of Singapore and to construct 3D models of marine structures for inspection and harbor navigation are presented. The system was successfully tested in seawater environments around Singapore where the water current is around 1-2m/s. Topics: Inspection , Modeling , Sensor networks , ShorelinesSingapore. National Research Foundation (Singapore-MIT Alliance for Research and Technology (SMART)

Fully Self-Contained, Enclosed, Mobile Welding Trailer

The Purpose of this project was to create a fully self contained, enclosed, mobile welding trailer for Alvarado Land and Cattle in Shandon, CA. The trailer was created to help bridge the financial gap between growing seasons. The added income from the mobile welding operation would provide much needed financial support to allow for more investment and expansion. Alvarado Land and Cattle reasoned that diversifying their operations by adding a mobile welding operation would be a smart step towards the success of the company. This trailer when completed will fulfill the need generated by the diversification

Impact of AMPA (Aminomethylphosphonic Acid) on the Fertility of Live Bearing Fish

Increases in metabolic disorders, fertility issues, and population numbers have led researchers to begin investigations into pesticides for the likelihood that their introduction into the agricultural industry as well as the permeation of these chemicals into natural habitats has been a contributing factor to the prevalence of these issues. Aminomethylphosphonic acid (AMPA) has been one of the dominant prospective chemicals for investigation for its prevalence and infiltration into both food products as well as within environmental reservoirs. As the research into whether these pesticide breakdown products have the potential to act as metabolic inhibitors or hormonal disruptors further research is needed. P. reticulata is a live-bearing fish model, making it ideal for research of this nature. P. reticulata live-bearing reproduction allows for the investigation into both short-term direct contact study as well as generational permeation of the fish, this being researching the capability to impact the fish bred by mothers exposed to the chemicals but not themselves directly. This may also give insight into mammalian models such as humans as the live-bearing model closely mimics the reproduction of mammalians. Using the P. reticulata model we developed methods for researching the impact of food spiked with the AMPA on the fertility of the mothers. Spiking the food directly better models the infiltration and accumulation of the AMPA within the trophic system of the aquatic environments. In addition to these preliminary runs, we developed methods for further runs as well as new testing parameters for further quantification of the impact of the AMPA on the fish’s fertility. Keywords: Aminomethylphosphonic acid, P. reticulata, fertility, live-bearing fish, hormonal disruptors, metabolic inhibitors

Quantifying Inactive Lithium in Lithium Metal Batteries

Inactive lithium (Li) formation is the immediate cause of capacity loss and catastrophic failure of Li metal batteries. However, the chemical component and the atomic level structure of inactive Li have rarely been studied due to the lack of effective diagnosis tools to accurately differentiate and quantify Li+ in solid electrolyte interphase (SEI) components and the electrically isolated unreacted metallic Li0, which together comprise the inactive Li. Here, by introducing a new analytical method, Titration Gas Chromatography (TGC), we can accurately quantify the contribution from metallic Li0 to the total amount of inactive Li. We uncover that the Li0, rather than the electrochemically formed SEI, dominates the inactive Li and capacity loss. Using cryogenic electron microscopies to further study the microstructure and nanostructure of inactive Li, we find that the Li0 is surrounded by insulating SEI, losing the electronic conductive pathway to the bulk electrode. Coupling the measurements of the Li0 global content to observations of its local atomic structure, we reveal the formation mechanism of inactive Li in different types of electrolytes, and identify the true underlying cause of low Coulombic efficiency in Li metal deposition and stripping. We ultimately propose strategies to enable the highly efficient Li deposition and stripping to enable Li metal anode for next generation high energy batteries

Establishing the First Student-Run Clinic to Provide Free Health Care to a South Texas Colonia

The University of Texas Rio Grande Valley School of Medicine (UTRGVSoM) opened its student-run clinic (SRC) in March 2018 to provide free health care for the residents of Pueblo de Palmas colonia in Hidalgo County. Located along the United States-Mexico border near some of the country\u27s poorest and most medically underserved communities, UTRGVSoM has the unique opportunity to extend quality primary care to those who otherwise would go without. The physical location of the clinic was determined by a partnership with Proyecto Desarrollo Humano, a nonprofit organization within the Pueblo de Palmas colonia. The free clinic, located in the town’s community center, opens its doors to the public every month on a chosen Saturday. This article hopes to detail the experience of being the first SRC to operate inside a Texas colonia

Competing Supramolecular Forces: Boron Coordination vs π-π Stacking

This study explores the impact of fluorination levels in azopyridine Lewis bases on their ability to direct the formation of B←N coordination adducts or cocrystals with phenylboronic ester. We hypothesize that the degree of fluorination can be used as a tool to control the outcome of supramolecular bonding competition, thus influencing complex self-assembly. A series of azopyridines with varying degrees of fluorination were synthesized and reacted with phenylboronic ester. Their structures were analyzed using Hartree-Fock calculations, Hirshfeld surface analyses, and single crystal X-ray diffraction to assess the impact of fluorination on supramolecular interactions. The study reveals that azopyridines with up to two fluorine atoms form B←N coordination complexes, while perfluorinated azopyridine leads to cocrystal formation through π-stacking interactions. The outcome depends on the electronic properties of the pyridyl nitrogens, influenced by the level of fluorination. Fluorination in azopyridine Lewis bases serves as an effective strategy to modulate supramolecular bonding competition between boron coordination and π-stacking. This approach enables the selective formation of desired supramolecular structures, highlighting the utility of fluorination in guiding the self-assembly process. The findings have implications for the development of functional materials and 2D devices, offering a novel method for controlling the architecture of supramolecular assemblies

Engineering Lipophilic Aggregation of Adapalene and Adamantane-Based Cocrystals via van der Waals Forces and Hydrogen Bonding

Lipophilic aggregation using adamantanes is a widely exploited molecular property in medicinal and materials chemistry. Adamantanes are traditionally installed to molecular units via covalent bonds. However, the noncovalent installation of adamantanes has been relatively underexplored and presents the potential to bring properties associated with adamantanes to molecules without affecting their intrinsic properties (e.g., pharmacophores). Here, we systematically study a series of adamantanecarboxylic acids with varying substitution levels of methyl groups and their cocrystals with bipyridines. Specifically, single-crystal X-ray diffraction shows that while the directionality of single-component adamantanes is notably sensitive to changes in methyl substitution, hydrogen-bonded cocrystals with bipyridines show consistent and robust packing due to π-stacking predominance. Our observations are supported by Hirshfeld surface and energy framework analyses. The applicability of cocrystal formation of adamantanes bearing carboxylic acids was used to generate the first cocrystals of adapalene, an adamantane-bearing retinoid used for treating acne vulgaris. We envisage our study to inspire noncovalent (i.e., cocrystal) installation of adamantanes to generate lipophilic aggregation in multicomponent systems

Confinement and Separation of Benzene from an Azeotropic Mixture Using a Chlorinated B←N Adduct

Separations of azeotropic mixtures are typically carried out using energy-demanding processes (e.g., distillation). Here, we report the capacity of a self-assembled chlorinated boronic ester-based adduct to confine acetonitrile and benzene in channels upon crystallization. The solvent confinement occurs via a combination of hydrogen bonding and [π···π] interactions. Quantitative separation of benzene from an azeotropic 1:1 mixture of a benzene/acetonitrile (v/v), and methanol is achieved through crystallization with the chlorinated adduct by complementary [C–H···O] and [C–H···π] interactions. Inclusion behavior is rationalized by molecular modeling and crystallographic analysis. The chlorinated boronic ester adduct shows the potential of modularity via isosteric substitution for the separation of challenging chemical mixtures (e.g., azeotropes)

Multivisceral resection of pancreatic neuroendocrine tumours: a report of two cases

Pancreatic neuroendocrine tumours (pNETs) are rare and surgical resection offers the only possibility of cure for localised disease. The role of surgery in the setting of locally advanced and metastatic disease is more controversial. Emerging data suggests that synchronous surgical resection of pancreas and liver may be associated with increased survival. We report two cases of synchronous, one stage multivisceral resections for pNET and associated reconstruction. We highlight the technical issues involved in such extensive resections and demonstrate that one stage multivisceral operations can be achieved safely