The Failure of Teton Dam – A New Theory Based on State Based Soil Mechanics

Teton Dam failed during its first filling on 5 June 1976. The 405-ft high dam was designed and built using modern standards; therefore its failure received considerable scrutiny from engineering experts. Failure mechanisms suggested, included hydraulic fracture, internal erosion, wet-seam theory, and defects in the abutment rock. None of the investigations, however, were able to explain satisfactorily why the dam breached when the reservoir reached EL.5301.7 ft and only in the vicinity of Sta. 14+00 on the right abutment. The investigation here is focused on this crucial aspect of the failure using the modern framework of fundamental “state based soil mechanics”. According to this framework highly compacted soils of low plasticity in an environment of low liquidity index and low confining stress would crack in the presence of high shear stresses. The impervious core (Zone-1) of Teton was constructed of uniform clayey silt of low plasticity and highly compacted and therefore was prone to such a possibility. This paper describes the details of the theory, the investigation, and the conclusions arrived at regarding the potential initiation of Teton failure. Finite element analysis carried out using state based parameters indicate the presence of deep open transverse vertical crack(s) in the core (Zone-1) to a maximum depth of about 32 ft from the crest only in the right abutment and in the vicinity of Sta. 14+00. We conclude that once the water level in the reservoir rose above El 5300.0 ft in the early hours of 5 June 1976 water flowed through the open vertical crack(s), which slowly eroded the crack into a large tunnel leading to the major breach of the dam hours later

Growth of CZTS Thin Films by Cosputtering of Metal Targets and Sulfurization in H2S

Copper zinc tin sulfide (CZTS) is an emerging thin film photovoltaic material. Chemical composition and phase purity are important factors which decide the quality of the film for photovoltaic applications. In the present work, we report the results of the morphological, structural, optical, and electrical characterizations of Cu2ZnSnS4 thin films, synthesized by sulfurizing magnetron cosputtered Cu2ZnSn thin films in ambient H2S. To the best of our knowledge, this is the first report on CZT deposition by cosputtering from Cu, Zn, and Sn targets and sulfurizing it in ambient H2S for making CZTS thin films. GIXRD and Raman study results showed that the film was kesterite CZTS. Optical absorbance studies revealed a band gap value of similar to 1.5 eV for CZTS thin film. Results of the Hall effect measurements are also reported

Signaling via a CD27-TRAF2-SHP-1 axis during naive T cell activation promotes memory-associated gene regulatory networks.

The interaction of the tumor necrosis factor receptor (TNFR) family member CD27 on naive CD8 <sup>+</sup> T (Tn) cells with homotrimeric CD70 on antigen-presenting cells (APCs) is necessary for T cell memory fate determination. Here, we examined CD27 signaling during Tn cell activation and differentiation. In conjunction with T cell receptor (TCR) stimulation, ligation of CD27 by a synthetic trimeric CD70 ligand triggered CD27 internalization and degradation, suggesting active regulation of this signaling axis. Internalized CD27 recruited the signaling adaptor TRAF2 and the phosphatase SHP-1, thereby modulating TCR and CD28 signals. CD27-mediated modulation of TCR signals promoted transcription factor circuits that induced memory rather than effector associated gene programs, which are induced by CD28 costimulation. CD27-costimulated chimeric antigen receptor (CAR)-engineered T cells exhibited improved tumor control compared with CD28-costimulated CAR-T cells. Thus, CD27 signaling during Tn cell activation promotes memory properties with relevance to T cell immunotherapy

What information and the extent of information research participants need in informed consent forms: a multi-country survey

Background: The use of lengthy, detailed, and complex informed consent forms (ICFs) is of paramount concern in biomedical research as it may not truly promote the rights and interests of research participants. The extent of information in ICFs has been the subject of debates for decades; however, no clear guidance is given. Thus, the objective of this study was to determine the perspectives of research participants about the type and extent of information they need when they are invited to participate in biomedical research. Methods: This multi-center, cross-sectional, descriptive survey was conducted at 54 study sites in seven Asia-Pacific countries. A modified Likert-scale questionnaire was used to determine the importance of each element in the ICF among research participants of a biomedical study, with an anchored rating scale from 1 (not important) to 5 (very important). Results: Of the 2484 questionnaires distributed, 2113 (85.1%) were returned. The majority of respondents considered most elements required in the ICF to be \u27moderately important\u27 to \u27very important\u27 for their decision making (mean score, ranging from 3.58 to 4.47). Major foreseeable risk, direct benefit, and common adverse effects of the intervention were considered to be of most concerned elements in the ICF (mean score = 4.47, 4.47, and 4.45, respectively). Conclusions: Research participants would like to be informed of the ICF elements required by ethical guidelines and regulations; however, the importance of each element varied, e.g., risk and benefit associated with research participants were considered to be more important than the general nature or technical details of research. Using a participant-oriented approach by providing more details of the participant-interested elements while avoiding unnecessarily lengthy details of other less important elements would enhance the quality of the ICF

Growth of CZTS by co-sputtering and sulfurization for solar cell applications

Earth abundant copper-zinc-tin-sulfide (CZTS) is an important class of materials for the development of low cost and sustainable thin film solar cells. Fabrications of CZTS thin film is carried out by magnetron co-sputtering the metallic and sulfide targets and post deposition sulfurization. We sputter Cu using DC power and ZnS and SnS using RF power. In order to study its structured properties and to establish the best growth conditions, Raman spectroscopy and Glazing incidence XRD analysis were carried out. These studies indicated that the grown CZTS film have a kesterite structure with good crystallinity and a strong preferential orientation along (112) plane. SEM analysis revealed a homogeneous, compact surface morphology and large grains throughout the thickness of the film. The grown CZTS film demonstrated an optical absorption coefficient higher than similar to 6x10(4)cm(-1) and optical band gap of 1.45 eV. The sheet resistance, carrier concentration, mobility and activation energy of the CZTS film were 2.52 k Omega, 1.86 x 10(18) cm(-3), 1.92 cm(2)V(-1)s(-1), and 37.8 meV, respectively. These optical and electrical properties are suitable for thin film solar cell fabrication

Electrical characterization of grain boundaries of CZTS thin films using conductive atomic force microscopy techniques

Electrical characterization of grain boundaries (GB) of Cu-deficient CZTS (Copper Zinc Tin Sulfide) thin films was done using atomic force microscopic (AFM) techniques like Conductive atomic force microscopy (CAFM), Kelvin probe force microscopy (KPFM) and scanning capacitance microscopy (SCM). Absorbance spectroscopy was done for optical band gap calculations and Raman, XRD and EDS for structural and compositional characterization. Hall measurements were done for estimation of carrier mobility. CAFM and KPFM measurements showed that the currents flow mainly through grain boundaries (GB) rather than grain interiors. SCM results showed that charge separation mainly occurs at the interface of grain and grain boundaries and not all along the grain boundaries

Effect of temperature on thermal expansion and anharmonicity in Cu2ZnSnS4 thin films grown by co-sputtering and sulfurization

Copper zinc tin sulfide (CZTS, made from the earth abundant and non-toxic materials) is a quaternary semiconducting compound which has received increasing interest for solar cells applications. In this study, CZTS thin film has been grown by co-sputtering Cu, Zn and Sn metal targets and sulfurizing it in H2S. XRD, SEM, EDS, XRF and optical studies show that these films are suitable for solar cell applications. The temperature-dependent Raman spectroscopic study on CZTS thin film was carried out in the temperature range of 80-450 K. A decrease in the intensity of "A" mode Raman peaks, shift of Raman peaks towards lower frequency and increase in the line width have been observed with increase in temperature. Raman "A" mode shifts from 337 cm(-1) at 80 K to 329 cm(-1) at 450 K. The peak at 288 cm(-1) disappears when the measurement was taken at 450 K. Based on experimental results and fittings of anharmonic equation; it has been shown that these effects are due to thermal expansion and interaction of the phonon with other phonons which arise at higher temperature. These phonons interact resulting in damping of the "A" mode phonon intensity. It was concluded that in order to truly analyze multicomponent compounds, Raman studies should be carried out at low temperature