Status of flexible CIS research at ISET

Polycrystalline thin film solar cells fabricated on light-weight, flexible substrates are very attractive for space applications. In this work CulnSe2 (CIS) based thin film devices were processed on metallic foil substrates using the selenization technique. CIS deposition method involved reaction of electron-bean evaporated Cu-In precursor layers with a selenizing atmosphere at around 400 C. Several metallic foils such as Mo, Ti, Al, Ni, and Cu were evaluated as possible substrates for these devices. Solar cells with AM1.5 efficiencies of 9.0-9.34 percent and good mechanical integrity were demonstrated on Mo and Ti foils. Monolithic integration of these devices was also demonstrated up to 4 in x 4 in size

Efficient CuInSe 2 Solar Cells Fabricated by a Novel Ink Coating Approach

A novel technique is developed for the deposition of CuInSe 2 (CIS) thin films for solar cell applications. The technique uses an ink formulation that contains Cu-In metallic pigments. A precursor layer is first formed coating this ink onto the selected substrate. The precursor film is then reacted with Se to form the CIS compound. Solar cells were fabricated on CIS absorber layers prepared by this low cost ink coating approach and devices with a conversion efficiency of over 9.0% were demonstrated. © 1998 The Electrochemical Society. S1099-0062(98)08-063-8. All rights reserved. Manuscript submitted August 14, 1998; revised manuscript received September 9, 1998. Available electronically October 1, 1998. Group I-III-VI materials are considered to be highly promising as absorber layers in high-efficiency thin film solar cell structures. In fact, the highest efficiency thin film device to date was produced on a Cu(In,Ga)Se 2 (CIGS) absorber film grown by a vacuum evaporation technique. The demonstrated conversion efficiency of 17.7% confirmed the capability of this material to yield highly efficient active devices when employed in thin film solar cell structures. High-efficiency solar cells have commonly been fabricated on CuInSe 2 (CIS) or CIGS absorbers deposited by costly vacuum deposition techniques such as coevaporation 1 and two-stage processes utilizing evaporation or sputtering. 2 There is presently great interest in the development of new lower cost processing methods for the growth of high quality CIS-type absorbers for thin film solar cell applications. Slurry or ink deposition by large area nonvacuum coating methods such as screen printing, spraying, curtain coating, roll coating, or doctor blading are attractive low-cost approaches for the growth of thin film solar cell absorbers, provided that the precursor layers obtained by these deposition techniques can be converted into high quality semiconductor films that are required for solar cell fabrication. There have been several attempts to deposit CIS absorbers using the screen printing technique. For example, Arita et al. described a method that involved (i) mixing pure Cu, In, and Se powders in the compositional ratio of 1:1:2, (ii) milling these powders in a ball mill and forming a screen printable paste, (iii) screen printing the paste on a substrate, and (iv) sintering this precursor film to form the compound layer. As can be seen from the review of previous work, the nature of the ingredients in the formulation of a paste or an ink is very important for the formation of a precursor layer which can later be converted into a high quality CIS-type compound film with properties that are desirable for solar cell applications. In this article we report a low-cost ink coating technique that was successfully employed for the deposition of CIS absorbers that could be used for the fabrication of over 9% efficient thin film solar cells. Experimental The general steps of the low-cost process used in this work for the growth of thin film CIS absorbers are schematically shown in The source of Cu and In in this work was a Cu-In alloy powder with a preselected and fixed Cu/In stoichiometric ratio. The Cu-In alloy powder was obtained by the melt atomization technique. To prepare the powder, 99.99% pure Cu and 99.99% pure In were melted under a hydrogen curtain at above 900°C. The Cu/In ratio of the melt corresponded to the targeted value range of 0.87-0.9. The melted alloy was transformed into powder in a gas atomizer employing Ar as the quenching gas. Quenched powder was collected at the bottom of the reactor and sieved to separate the particles that were smaller than 20 µm in size which were used in this work as the pigment. About 10 g of the Cu-In pigment was mixed with 23 g of water. A small amount (about 1.5 wt %) of a wetting agent and dispersant were added to this aqueous formulation. The mixture was milled in a ball mill for 42 h. The resulting metallic ink was water-thin. Particle size analysis was done on a sample of this ink using

A phase 1b open-label dose-finding study of ustekinumab in young adults with type 1 diabetes

Aim We assessed the safety of ustekinumab (a monoclonal antibody used in psoriasis to target the IL-12 and IL-23 pathways) in a small cohort of recent-onset (<100 days of diagnosis) adults with type 1 diabetes (T1D) by conducting a pilot open-label dose-finding and mechanistic study (NCT02117765) at the University of British Columbia. Methods We sequentially enrolled 20 participants into four subcutaneous dosing cohorts: i) 45mg loading-weeks 0/4/16, ii) 45mg maintenance-weeks 0/4/16/28/40, iii) 90mg loading-weeks 0/4/16 and iv) 90mg maintenance-weeks 0/4/16/28/40. The primary endpoint was safety as assessed by an independent data and safety monitoring board (DSMB) but we also measured mixed meal tolerance test C-peptide, insulin use/kg, and HbA1c. Immunophenotyping was performed to assess immune cell subsets and islet antigen-specific T cell responses. Results Although several adverse events were reported, only two (bacterial vaginosis and hallucinations) were thought to be possibly related to drug administration by the study investigators. At 1 year, the 90mg maintenance dosing cohort had the smallest mean decline in C-peptide AUC (0.1pmol/mL). Immunophenotyping showed that ustekinumab reduced the percentage of circulating Th17, Th1 and Th17.1 cells and proinsulin-specific T cells that secreted IFN-γ and IL-17A. Conclusion Ustekinumab was deemed safe to progress to efficacy studies by the DSMB at doses used to treat psoriasis in adults with T1D. A 90mg maintenance dosing schedule reduced proinsulin-specific IFN-γ and IL-17A-producing T cells. Further studies are warranted to determine if ustekinumab can prevent C-peptide AUC decline and induce a clinical response

Facilitating the Recruitment of Minority Ethnic People into Research: Qualitative Case Study of South Asians and Asthma

Aziz Sheikh and colleagues report on a qualitative study in the US and the UK to investigate ways to bolster recruitment of South Asians into asthma studies, including making inclusion of diverse populations mandatory

CIS-Type PV Device Fabrication by Novel Techniques; Phase I Annual Technical Report, 1 July 1998 - 30 June 1999

This report describes work performed by International Solar Electric Technology, Inc. (ISET) during phase I of the R&amp;D partnership subcontract titled ''CIS-Type PV Device Fabrication by Novel Techniques.'' The objective of this program is to bring ISET's novel non-vacuum CIS technology closer to commercialization by concentrating on issues such as device-efficiency improvement, larger-bandgap absorber growth, and module fabrication. Advances made in CIS and related compound solar cell fabrication processes have clearly shown that these materials and device structures can yield power conversion efficiencies in the 15%-20% range. However, many of the laboratory results on CIS-type devices have been obtained using relatively high-cost vacuum-based deposition techniques. The present project was specifically geared toward developing a low-cost, non-vacuum ''particle deposition'' method for CIS-type absorber growth. There are four major processing steps in this technique: (i) preparation of a starting powder containing all or some of the chemical species constituting CIS, (ii) preparation of an ink using the starting powder, (iii) deposition of the ink on a substrate in the form of a thin precursor layer, and (iv) conversion of the precursor layer into a fused photovoltaic absorber through annealing steps. During this Phase I program, ISET worked on tasks that were geared toward the following goals: (i) elimination of back-contact problems, (ii) growth of large-bandgap absorbers, and (iii) fabrication of mini-modules. As a result of the Phase I research, a Mo back-contact structure was developed that eliminated problems that resulted in poor mechanical integrity of the absorber layers. Sulfur inclusion into CIS films through high-temperature sulfurization in H{sub 2}S gas was also studied. It was determined that S diffusion was a strong function of the stoichiometry of the CIS layer. Sulfur was found to diffuse rapidly through the Cu-rich films, whereas the diffusion constant was at least three orders of magnitude smaller in Cu-poor layers. Additionally, S profiles in sulfurized CIS films were correlated with the distribution of the grain size through the film. Absorbers containing large concentrations of Ga near the Mo contact interface also had large S content in that same region due to the small grain size of the Ga-containing material. New work on monolithic integration procedures overcame the problem of low shunt resistance and yielded CuIn(S,Se){sub 2} (CISS) mini-modules of about 64-cm{sup 2} area with close to 7% efficiency

Global Vipassana Pagoda: Exterior Geometry Envelope Extraction Using UAV Photogrammetry

The Global Vipassana Pagoda is the largest meditation hall in the world, located near Gorai, north west of Mumbai, Maharashtra, India. Although the monument's artistic integrity is still somewhat intact, material degradation and structural deformations are observed. The visual inspections of such monuments are the primary and most important practice subject to both natural hazards and deterioration over time. Therefore, the geometry envelope, dimension, and size of the monument have to be monitored and digitally captured in order to evaluate this structural deformation. In this paper, in order to acquire Global Vipassana Pagoda monument's efficient visual inspections and a 3D model of a historic masonry, advanced survey procedures UAV photogrammetry survey is used. But, due to its complex geometry and substantial dimensions, the exterior geometry envelope of the monument is difficult to generate. As a result, while conducting UAV surveys it's important to correctly design the flight plan, the photogrammetric parameters and the georeferencing configuration. The research aims to generate external geometry envelopes that serve as an input for an analyst to monitor the structural deformations of the monuments. The intended results were achieved after carrying out various trials of UAV surveys for Global Vipassana Pagoda monuments. Finally, the study enlists the factors and approach required to generate the external geometry envelope of complex monuments using UAV survey

MLH1 germline epimutations as a factor in hereditary nonpolyposis colorectal cancer

Copyright © 2005 American Gastroenterological Association Published by Elsevier Inc.Background & aimsHereditary nonpolyposis colorectal cancer (HNPCC) is caused by heterozygous germline sequence mutations of DNA mismatch repair genes, most frequently MLH1 or MSH2. A novel molecular mechanism for HNPCC has recently been suggested by the finding of individuals with soma-wide monoallelic hypermethylation of the MLH1 gene promoter. In this study, we determined the frequency and role of germline epimutations of MLH1 in HNPCC.MethodsA cohort of 160 probands from HNPCC families who did not harbor germline sequence mutations in the mismatch repair genes were screened for methylation of the MLH1 and EPM2AIP1 promoters by combined bisulfite and restriction analyses. Allelic expression and family transmission of MLH1 were determined using polymorphisms in intron 4 and the 3' untranslated region.ResultsOne of 160 individuals had monoallelic MLH1 hypermethylation in peripheral blood, hair follicles, and buccal mucosa, indicative of a soma-wide alteration. Monoallelic transcription of the paternal MLH1 allele was shown using a heterozygous expressed polymorphism within the 3' untranslated region. The hypermethylated allele was maternally transmitted, however, the mother and siblings who inherited the same maternal homologue were unmethylated at MLH1, suggesting the epimutation arose as a de novo event.ConclusionsGermline MLH1 epimutations are functionally equivalent to an inactivating mutation and produce a clinical phenotype that resembles HNPCC. Inheritance of epimutations is weak, so family history is not a useful guide for screening. Germline epimutations should be suspected in younger individuals without a family history who present with a microsatellite unstable tumor showing loss of MLH1 expression.Megan Hitchins, Rachel Williams, Kayfong Cheong, Nimita Halani, Vita A.P. Lin, Deborah Packham, Sue Ku, Andrew Buckle, Nicholas Hawkins, John Burn, Steven Gallinger, Jack Goldblatt, Judy Kirk, Ian Tomlinson, Rodney Scott, Allan Spigelman, Catherine Suter, David Martin, Graeme Suthers, Robyn War