Mechanical Transduction of a Single Cell: Possible Applications for 3D Printed Lab-on-a-Chip

Mechanical signalling plays an important role in cell morphology, communication, migration, adhesion and differentiation. It is essential for the cell to translate mechanical forces into biochemical signals; known as mechanical transduction. This research offers a platform called 3D ‘lab-on-a-chip’ for investigating the effects of mechanical confinement in cells growth, gene expressions, motility, stress and diffusion. Lab-on-a-chip devices are miniature device that can shrink a conventional bench-top laboratory into a small chip. Compared to existing glass/semiconductor based platforms for cell mechanical transduction, our aim is to develop an alternate cost-effective platform using 3D printed lab-on-a-chip. Such a platform is reconfigurable, adaptable with rapid manufacturing and cost effective. The 3D microfluidic devices allow for mechanical transduction of a single cell within three dimensional micro channels designed specifically to the researchers needs. It is crucial to understand the mechanical transduction of the cell to be analyzed as the amount of stress exerted should be moderated to avoid destroying valuable cellular components. An application of this research is isolation of cancer cells. As cancer cells progress, cytoskeletal proteins transform leading to a change in deformability, contraction and elasticity as compared to a regular cell. By understanding the differences between different types of cell morphology and deformability, a 3D printable lab on a chip device can be designed to isolate the cell and mechanically transduce it to release its components for analysis. Our research utilizes finite element based analysis to design such a 3D lab-on-chip. Based on the amount of stress required to break the cell into components, the state of the cell can be determined. Understanding the kinetics and components of the cell cytoskeleton is important in the use of lab-on-a-chip devices which can also allow for a wide variety of other applications such as cell isolation, cell lysis, genomics, and cell state detection

Development of A Robust, Soft and Flexible Selfhealing Polymer Based on Dynamic Coordinate Metallig and Bonds

Herein, an intrinsic autonomous self-healing polymer system has been developed and explored leading to new materials that are easily able to be fine-tuned both mechanically and chemically. Through an easy condensation reaction, the system explored incorporates dynamic and reversible bonds within polydimethylsiloxane monomer chains, namely dynamic imine and metal-coordinated bonds, to enable autonomous self-healing while also allowing for simple alteration of the system through manipulation of the metal salt used to coordinate the ligands of the monomer units. In addition to the autonomous self-healing of the system, controlled degradability at mild pH and ultra-high stretchability (up to 800% strain) are possible through alteration of the metal to ligand ratio and type of metal used in the coordination. Characterization of this dynamic system was performed through a variety of techniques such as tensile-pull strain testing, atomic force microscopy, UV-Vis spectroscopy, dynamic mechanical analysis, and shear rheology which showed that the highly dynamic imine bonds combined with the coordination with various transition metal salts allowed for the material to regenerate up to 88 % of its mechanical strength after physical damage while also being able to generate materials that ranged in their Young’s modulus from approximately 0.2 MPa to 10 MPa through simply altering the bonds formed through the metal ligand coordination interaction. Results suggest the mechanical properties of the system under investigation is directly related to its ability to regenerate upon damage. The new soft polymer has also been used as a dielectric layer in a capacitive based pressure sensor that is able to regenerate its mechanical and electrical properties upon damage, proving the possibility of our self-healing polymer for use in the next generation of self-healing electronics

Fuga de capitales: un debate actual en el marco del intercambio del flujo de fondos internacional

Con el desembarco de las nuevas tecnologías y el auge de la concentración de la riqueza, cobra cada vez mayor relevancia el volumen de excedente económico que escapa de las fronteras nacionales, en países como Argentina. A nivel global han surgido mecanismos de intercambio de información tributaria con el fin de detectar la elusión y evasión tributaria de nacionales en otras jurisdicciones. Adicionalmente en Argentina hemos tenido desequilibrios macroeconómicos que nos han llevado a un estricto control de cambios.Instituto de Relaciones Internacionale

A Comparative Analysis of Capacitive Based Flexible Pressure Sensors

A Comparative Analysis of Capacitive Based Flexible Pressure Sensors Julia Pignanelli1, Dr. Simon Rondeau-Gagne2 and Dr. Jalal Ahamed3 Department of Biology, University of Windsor Department of Chemistry & Biochemistry, University of Windsor Mechanical, Automotive and Materials Engineering Department, University of Windsor This paper presents the material characterization of a flexible polymer for potential biomedical pressure sensing applications. The emergence of flexible, capacitive based pressure sensors with similar tactile sensing properties as human skin are highly desirable in many applications such as continuous cardiovascular monitoring, electronic skin and rehabilitation technologies [2,3]. Most of these sensors require high sensitivity, fast response time, flexibility and low cost. Due to flexible and foldable nature of the sensor, it can be integrated to artificial skin or imposed on the body surface. Among different sensing technologies, one promising method is through the use of micro-structured, flexible, dielectric polymers, for example PDMS (Polydimethylsiloxane). Micro-structures increase the sensitivity of the device. Current methods for constructing micro-patterns into the PDMS requires expensive and labor intensive methods such as photolithographic techniques and chemical etching, which lack low-cost and large-area compatible alternatives. The objective of this work is to construct and characterize a flexible capacitor pressure sensing device by using a simple, cost effective method of PDMS microstructuring as described by previously by Grzybowki et al. [1]. The PDMS was prepared by mixing 20 parts elastomer and 1 part curing agent. The rough structured PDMS is prepared by simply curing the polymer within an epoxy mold that incorporates a micro – pattern like design found within a commercially available tape [1]. The sample was placed in a vacuum for one hour at room temperature and then cured for another 24 hours at room temperature. Flexibility of the sensors is a key parameter related to sensor sensitivity. Flexibility can be measured by measuring the modulus of elasticity. Our test reveals the rough structured 20:1 PDMS modulus to be 1.29 MPa whereas the non-structured 20:1 PDMS modulus was found to be 2.90 MPa. The difference in moduli was not determined to be significant as expected since the structures are not changing the material property of PDMS. Through characterization and preparation of rough structured capacitive based PDMS pressure sensors, we hope to produce a capacitive sensing device with excellent detection sensitivity at a low cost and with a simple method of production. Refrences: Grzybowski, B., Qin, D., Haag, R., & Whitesides, G. (2000). Elastomeric optical elements with deformable surface topographies: applications to force measurements, tunable light transmission and light focusing. Sensors And Actuators A: Physical, 86(1-2), 81-85. Boutry, C., Nguyen, A., Lawal, Q., Chortos, A., Rondeau-Gagné, S., & Bao, Z. (2015). A Sensitive and Biodegradable Pressure Sensor Array for Cardiovascular Monitoring. Advanced Materials, 27(43), 6954-6961. Mannsfeld, S., Tee, B., Sltengerg, R, Chen, C.,,, Barman, S., Muir, B., Sokiloy, A., Reese, C. and Bao, Z. (2010). Highly sensitive flexible pressure sensors with microstrucutred rubber dielectric layers. Nature Materials, 9(10), 859-864

The effect of mTOR inhibitor rapamycin on a dietary Drosophila melanogaster model of calcium oxalate nephrolithiasis

Impaired cellular tolerance of reactive oxygen species (ROS) has been suggested as a common mechanistic link associated with aging in both metabolic syndrome and nephrolithiasis. The mechanistic (mammalian) target of rapamycin (mTOR) activity is characteristic of metabolic syndrome. When nutrients are abundant, mTOR is active. Conversely, fasting inhibits mTOR. Metabolic syndrome is correlated with an increased risk of self-reported or imaging findings of nephrolithiasis. At the individual level, patients with a higher BMI have an increased prevalence of recurrent symptomatic nephrolithiasis, 24-hour urinary excretion of oxalate, sodium, uric acid, calcium, and phosphorous as well as lower pH. Calcium oxalate crystals produce ROS in renal epithelial cells and upregulate ROS and also mTOR activity. Rapamycin pharmacologically inhibits mTOR leading to autophagy – a natural defense mechanism against ROS – and drives sub-cellular recycling machinery to a net catabolic state. Ideally, inhibiting mTOR limits the duration and degree of damage done by ROS and subsequent inflammatory process. Additionally, improved clearance of damaged organelles prevents runaway generation of ROS by mitochondrial dysfunction associated with calcium oxalate crystal adherence and internalization. Taken together, this may prevent the progression of calcium oxalate urolithiasis. In this study, we examined the effect of short-term intermittent rapamycin treatment on the area of calcium oxalate concretion in the Malpighian tubules of a Drosophila melanogaster fed a lithogenic diet containing 0.1% sodium oxalate

Los procesos de licitación privada y su óptima aplicación en empresas petroleras junior de capital nacional

El propósito de esta tesis fue proporcionar un procedimiento de licitación privada que optimice las contrataciones de equipos y servicios de perforación, ajustadas a las necesidades específicas de empresas petroleras de pequeño tamaño (menos de 400 empleados), fortaleciendo los controles necesarios para asegurar un proceso confiable, evitando asimetrías de información y conflicto de intereses como principal objetivo. La tesis tuvo como objeto de estudio a una empresa PyME, joven, de capitales nacionales: MSA

Excitation of the 21+ and 22+ states in the 88Sr(p, p′) reaction at 25 and 31 MeV:A look behind the nuclear surface

Data for the excitation of the 21+ and 22+ states in the 88Sr(p, p′) reaction at 25 and 31 MeV indicate substantial contributions from the interior of the nucleus, Microscopic DWBA calculations reproduce this and yield a fair description of the data. A detailed description, especially of the 22+ state, is sensitive to the effective nucleon-nucleon interaction used and the non-locality of the optical potential, which are insufficiently known at present

Angular distribution of photons from the delay of the GDR in hot and rotating light Yb nuclei from exclusive experiments

Abstract Angular distributions of photons associated with the damping of excited-state giant dipole resonances (GDR) in hot and rotating 161,162 Yb nuclei have been measured in exclusive experiments using the HECTOR array. In reactions with heavy ions ( 48 T) angular distributions are determined as a function of the angular momentum of the compound nuclei. In reactions with lighter ions ( 17,18 O) a difference method is applied to isolate GDR decays originating from specific excitation regions. The systematics of the measured angular distributions as a function of excitation energy and angular momentum are compared to theories taking into account fluctuations of the shape and orientation of the excited nuclei

Evaluating the Anti-cancer Efficacy of a Synthetic Curcumin Analog on Human Melanoma Cells and Its Interaction with Standard Chemotherapeutics

Melanoma is the leading cause of skin-cancer related deaths in North America. Metastatic melanoma is difficult to treat and chemotherapies have limited success. Furthermore, chemotherapies lead to toxic side effects due to nonselective targeting of normal cells. Curcumin is a natural product of Curcuma longa (turmeric) and has been shown to possess anti-cancer activity. However, due to its poor bioavailability and stability, natural curcumin is not an effective cancer treatment. We tested synthetic analogs of curcumin that are more stable. One of these derivatives, Compound A, has shown significant anti-cancer efficacy in colon, leukemia, and triple-negative inflammatory breast cancer cells. However, the effects of Compound A against melanoma cells have not been studied before. In this study, for the first time, we demonstrated the efficacy of Compound A for the selective induction of apoptosis in melanoma cells and its interaction with tamoxifen, taxol, and cisplatin. We found that Compound A induced apoptosis selectively in human melanoma cells by increasing oxidative stress. The anti-cancer activity of Compound A was enhanced when combined with tamoxifen and the combination treatment did not result in significant toxicity to noncancerous cells. Additionally, Compound A did not interact negatively with the anti-cancer activity of taxol and cisplatin. These results indicate that Compound A could be developed as a selective and effective melanoma treatment either alone or in combination with other non-toxic agents like tamoxifen

Angular momentum dependence of the GDR width in Sn nuclei at fixed excitation energy

Abstract High-energy γ-rays from the decay of the giant-dipole resonance (GDR) in the hot 106Sn compound nucleus and its daughters were measured in coincidence with heavy recoiling evaporation residues. The compound nucleus was formed at excitation energy E ∗ = 80 MeV using the reaction 56Ni+48Ti at a bombarding energy of 260 MeV. The analysis yields the GDR width for two different intervals of angular momentum 〈J〉 = 24 and 36ℏ. The present data, combined with previous data at higher angular momentum permit a study of the angular momentum dependence of the GDR width for 10 ⩽ J ⩽ 60ℏ at approximately fixed temperature. The width of the GDR is found to be roughly constant for