An approach for configuring space photovoltaic tandem arrays based on cell layer performance

Meeting solar array performance goals of 300 W/Kg requires use of solar cells with orbital efficiencies greater than 20 percent. Only multijunction cells and cell layers operating in tandem produce this required efficiency. An approach for defining solar array design concepts that use tandem cell layers involve the following: transforming cell layer performance at standard test conditions to on-orbit performance; optimizing circuit configuration with tandem cell layers; evaluating circuit sensitivity to cell current mismatch; developing array electrical design around selected circuit; and predicting array orbital performance including seasonal variations

Confinement induced instability of thin elastic film

A confined incompressible elastic film does not deform uniformly when subjected to adhesive interfacial stresses but with undulations which have a characteristic wavelength scaling linearly with the thickness of the film. In the classical peel geometry, undulations appear along the contact line below a critical film thickness or below a critical curvature of the plate. Perturbation analysis of the stress equilibrium equations shows that for a critically confined film the total excess energy indeed attains a minima for a finite amplitude of the perturbations which grow with further increase in the confinement.Comment: 11 pages, 6 figure

Method of fabricating a photovoltaic module of a substantially transparent construction

A method characterized by the steps of positioning a plurality of uniformly dimensioned photovoltaic cells in registered relation with a plurality of openings formed in a planar tool is disclosed. The method allows acess to the P contact surface of each of the cells. The steps of the method are: (1) connecting the N contact surface of alternate cells to the P contact surface of the cells interposed therebetween, (2) removing therefrom residue of solder flux, (3) applying to the N contact surfaces of the cells a transparent adhesive, (4) placing a common transparent cover plate in engaged relation with the adhesive, (5) placing a film over the circular openings for hermetically sealing the openings, and (6) establishing a vacuum between the film and the cover plate

Development and Characterization of a Recombinant Vesicular Stomatitis Virus (rVSV) for the Treatment of Glioblastoma

Background: Over the past 30 years, little has changed in the treatment modalities and prognosis of patients suffering from Glioblastoma multiforme (GBM), the most common and by far the most devastating adult primary malignant brain tumor. Conventional therapies provide only a marginal increase in survival of GBM patients, post-diagnosis. Therefore, more novel means of treating GBM are needed to increase long-term survival and quality of life for those affected. Replication competent oncolytic viruses (OVs) have recently emerged as a possible option for treatment of high-grade gliomas. Particularly, recombinant vesicular stomatitis virus (rVSV), an enveloped, negative strand RNA virus, has shown promising results in preclinical studies. Tumor selectivity of VSV is thought to be associated with tumor specific defects in the interferon (IFN) pathway. However, largely due to insufficient attention on the role the immune system plays in efficacy of treatment, potential OVs have been obstructed from moving through the clinical trial pipeline past Phase I/II studies. rNCP12.1 is a novel recombinant VSV vector possessing specific mutations in the matrix protein. Thes mutations have been shown to promote viral attenuation in normal cells while maintaining cytotoxicity in a number of tumor cell lines. We aim to characterize and further develop this novel agent for the treatment of GBM. Methods: In order to determine differences between rNCP12.1 and wtVSV and to determine specificity of rNCP12.1 for tumor over normal cells, cell rounding assays, one-step growth curves, and cytotoxicity assays were performed in normal glial and tumor glial cell lines. To understand the basis of this selectivity and whether it correlated with the antiviral responses of IFN, expression levels of IFN and IFN stimulated genes (ISGs) were quantified, production of active IFN was measured, and the ability of cells to inhibit viral infection in response to exogenous IFN was determined. In vivo experiments were designed and carried out to test for oncolytic activity of rNCP12.1 in immunocompetent animal models of intracranial glioma. A single injection of rNCP12.1 was administered into previously implanted F98-GFP tumors. Tumor load and parameters of morbidity were assessed at 15 days following tumor implantation and long term at the time of euthanasia. Viral induced immune responses were assessed by the IFN bioassay and detection of circulating anti-VSV antibodies were achieved by Western blot analysis and a neutralizing antibody assay. Experimental methods of virus administration for treatment of glioma were further tested including multiple injections, injections using different VSV serotypes, continuous infusion of virus using implantable osmotic pumps, and pre-infected autologous carrier cells. These methods were designed to enhance anti-tumor effect by managing the negative effects of the tumor microenvironment and of a functional immune system on viral therapy. Results and Conclusion: rNCP12.1 was shown to be an attenuated strain of VSV that has clear differences in its growth and induction of the IFN response pathway in normal cells. It has a preference for growth in tumor cells as determined by viral titers, cell rounding, and cell viability post infection. This preference varied based on cellular expression of a particular IFN phenotype. The importance of this molecular versus histological cell profile was evident even in the performance of rNCP12.1 on human glioma cell lines that differ in their expression of IFN. In vivo evaluation of rNCP12.1 against a highly IFN resistant rat glioma cell line, F98, demonstrated its ability to decrease tumor size while eliciting a peripheral response to virus that protects normal tissue but also shortens its therapeutic window and the ability to sustain reduction of tumor over time. Several experimental methods in delivery of virus proved to be beneficial, including administering an additional dose of virus using a different serotype to bypass antiviral neutralizing responses and by shielding virus from the immune system through the use of tumor carrier cells. As an additional benefit, the latter was shown to have a unique pattern in eliciting tumor specific antibodies that was different from those increased by therapy with virus alone. This method also increased recovery of virus from brain tissue even after 20 days post treatment. Our data supports the capability of rVSV vectors as treatment for GBM. Specifically rNCP12.1 therapy increased survival while decreasing tumor load, depending on method of administration. When given alone, virus is ultimately immunogenic and prompts anti-viral as well as anti-tumor immune responses. However, when shielded from the immune system, antiviral responses are minimal while anti-tumor responses are sustained. To this end, therapy cannot be fully addressed without addressing the effects the immune system has on therapy and on the host. Future studies, should include not only evaluation of tumor load, morbidity, and side effects of viral therapy but also immune responses especially those that are likely to enhance therapy past the acute stages of disease

Creep and creep rupture of laminated graphite/epoxy composites

An incremental numerical procedure based on lamination theory is developed to predict creep and creep rupture of general laminates. Existing unidirectional creep compliance and delayed failure data is used to develop analytical models for lamina response. The compliance model is based on a procedure proposed by Findley which incorporates the power law for creep into a nonlinear constitutive relationship. The matrix octahedral shear stress is assumed to control the stress interaction effect. A modified superposition principle is used to account for the varying stress level effect on the creep strain. The lamina failure model is based on a modification of the Tsai-Hill theory which includes the time dependent creep rupture strength. A linear cumulative damage law is used to monitor the remaining lifetime in each ply

Numerical solution methods for viscoelastic orthotropic materials

Numerical solution methods for viscoelastic orthotropic materials, specifically fiber reinforced composite materials, are examined. The methods include classical lamination theory using time increments, direction solution of the Volterra Integral, Zienkiewicz's linear Prony series method, and a new method called Nonlinear Differential Equation Method (NDEM) which uses a nonlinear Prony series. The criteria used for comparison of the various methods include the stability of the solution technique, time step size stability, computer solution time length, and computer memory storage. The Volterra Integral allowed the implementation of higher order solution techniques but had difficulties solving singular and weakly singular compliance function. The Zienkiewicz solution technique, which requires the viscoelastic response to be modeled by a Prony series, works well for linear viscoelastic isotropic materials and small time steps. The new method, NDEM, uses a modified Prony series which allows nonlinear stress effects to be included and can be used with orthotropic nonlinear viscoelastic materials. The NDEM technique is shown to be accurate and stable for both linear and nonlinear conditions with minimal computer time

Physical aging and solvent effects on the fracture of LaRC-TPI adhesives

When amorphous materials are quenched below their glass transition temperature, excess enthalpy is trapped in the glassy material because the viscosity is too great to allow the material to remain in volumetric equilibrium. Over time, this excess free volume is reduced as the material slowly approaches its equilibrium configuration. This process, known as physical aging, leads to substantial changes in the constitutive behavior of polymers, as has been widely discussed in the literature. Less is known about the effects of this physical aging process on fracture and fatigue properties of aged materials. The original goal of the summer was to investigate the effects of physical aging on the fracture and fatigue behavior of LaRC-TPI, a thermoplastic polyimide developed at NASA-Langley. Preliminary results are reported, although a lack of equipment availability prevented completion of this task. In the process of making specimens, the current LaRC-TPI was observed to be extremely susceptible to environmental stress cracking. A study of the unique failure patterns resulting from this degradation process in bonded joints was conducted and is also reported herein

Dynamic Change of Awareness during Meditation Techniques: Neural and Physiological Correlates

Recent fndings illustrate how changes in consciousness accommodated by neural correlates and plasticity of the brain advance a model of perceptual change as a function of meditative practice. During the mindbody response neural correlates of changing awareness illustrate how the autonomic nervous system shifts from a sympathetic dominant to a parasympathetic dominant state. Expansion of awareness during the practice of meditation techniques can be linked to the Default Mode Network (DMN), a network of brain regions that is active when the one is not focused on the outside world and the brain is restful yet awake (Chen et al., 2008). A model is presented illustrating the dynamic mindbody response before and after mindfulness meditation, and connections are made with prefrontal cortex activity, the cardiac and respiratory center, the thalamus and amygdala, the DMN and cortical function connectivity. The default status of the DMN changes corresponding to autonomic modulation resulting from meditation practice

Lightweight solar array blanket tooling, laser welding and cover process technology

A two phase technology investigation was performed to demonstrate effective methods for integrating 50 micrometer thin solar cells into ultralightweight module designs. During the first phase, innovative tooling was developed which allows lightweight blankets to be fabricated in a manufacturing environment with acceptable yields. During the second phase, the tooling was improved and the feasibility of laser processing of lightweight arrays was confirmed. The development of the cell/interconnect registration tool and interconnect bonding by laser welding is described

An autobiography of hands: on training in sleight of hand magic

Set in an autobiographical frame, this text describes the intensive process of training in sleight of hand magic, what happened when this training was subsequently abandoned, and how it is now being resumed