Synthesis of 3-stannyl and 3-silyl propargyl phosphanes and the formation of a phosphinoallene

The group 14 chloropropargyls R3ECCCH2Cl (R3E = Bu3Sn, Ph3Sn, Me2PhSi, iPr3Si, nPr3Si, nBu3Si), obtained by a modified literature procedure, react with LiPPh2 to afford the novel propargyl phosphanes Ph2PCH2CCER3 in high yield, as viscous oils; (Me3Si)2PCH2CCSiPhMe2 is similarly obtained from LiP(SiMe3)2. In contrast, the reaction of PhCCCH2MgCl with ClP(NEt2)2 fails to produce a comparable propargyl phosphane, but generates preferentially (>70%) the novel phosphinoallene (Et2N)2PC(Ph)=C=CH2, which is characterised spectroscopically, and through its reaction with HCl. The coordination chemistry of representative phosphanes is explored with respect to platinum and palladium for the first time

Exploring Flood Response Challenges, Training Needs, and the Impact of Online Flood Training for Lifeguards and Water Safety Professionals in South Africa

Flooding is a significant cause of human and economic loss in the African region, including in South Africa. Flood mitigation and response in South Africa is challenging due to a range of environmental, infrastructure, and policy constraints. Lifeguards represent a potential additional workforce to bolster flood mitigation and response. This study aimed to explore the feasibility and acceptability of online flood safety training for water safety professionals in South Africa, as well as assess the current flood response capacity and future needs of this group. Online surveys were completed by a convenience sample of South African water safety professionals (including lifeguards) pre-and post a series of four online flood training workshops. Free text responses were thematically coded and flood knowledge was compared between the pre-and post-workshop survey respondents. Sixty-eight responses were analysed (64.7% pre-workshop phase; 63.2% male, 29.4% aged 50–59 years). A range of challenges in flood mitigation and response were identified including equipment, training, and a lack of government support. However, positives were also identified including respondents’ willingness to assist in flood emergencies and good cooperation with neighbouring countries and across the region. Opportunities for better cross-municipal and government communication were discussed. In times of crisis, or in resource poor settings, water safety professionals can bolster traditional flood mitigation and response capacity. Opportunities exist to harness this willingness, but also improve cross-governmental and municipal knowledge sharing to improve future flood mitigation and response efforts in South Africa

The Heart of the Matter: The Coaching Model in America's Choice Schools

The Consortium for Policy Research in Education (CPRE) at the University of Pennsylvania was contracted by the National Center on Education and the Economy (NCEE) in 1998 to conduct the external evaluation of the America's Choice school design. CPRE designed and conducted a series of targeted studies on the implementation and impacts of the America's Choice design. This report coincides with the publication of three separate studies by CPRE on the impact of America's Choice in a number of districts across the country using a variety of quantitative and analytic approaches. Those impact analyses and a stand-alone piece on classroom observations conducted in Cohort 4 schools can be viewed as separate pieces or as complements to the information presented in this report. Another recent CPRE publication from fall 2001 is a widely distributed report entitled, Instructional Leadership in a Standards-based Reform, a companion piece to both the impact reports and this report

The Heart of the Matter: The Coaching Model in America\u27s Choice Schools

The Consortium for Policy Research in Education (CPRE) at the University of Pennsylvania was contracted by the National Center on Education and the Economy (NCEE) in 1998 to conduct the external evaluation of the America’s Choice school design. CPRE designed and conducted a series of targeted studies on the implementation and impacts of the America’s Choice design. This report coincides with the publication of three separate studies by CPRE on the impact of America’s Choice in a number of districts across the country using a variety of quantitative and analytic approaches. Those impact analyses and a stand-alone piece on classroom observations conducted in Cohort 4 schools can be viewed as separate pieces or as complements to the information presented in this report. Another recent CPRE publication from fall 2001 is a widely distributed report entitled, Instructional Leadership in a Standards-based Reform, a companion piece to both the impact reports and this report

Small heat-shock proteins interact with a flanking domain to suppress polyglutamine aggregation

Small heat-shock proteins (sHsps) are molecular chaperones that play an important protective role against cellular protein misfolding by interacting with partially unfolded proteins on their off-folding pathway, preventing their aggregation. Polyglutamine (polyQ) repeat expansion leads to the formation of fibrillar protein aggregates and neuronal cell death in nine diseases, including Huntington disease and the spinocerebellar ataxias (SCAs). There is evidence that sHsps have a role in suppression of polyQ-induced neurodegeneration; for example, the sHsp alphaB-crystallin (αB-c) has been identified as a suppressor of SCA3 toxicity in a Drosophila model. However, the molecular mechanism for this suppression is unknown. In this study we tested the ability of αB-c to suppress the aggregation of a polyQ protein. We found that αB-c does not inhibit the formation of SDS-insoluble polyQ fibrils. We further tested the effect of αB-c on the aggregation of ataxin-3, a polyQ protein that aggregates via a two-stage aggregation mechanism. The first stage involves association of the N-terminal Josephin domain followed by polyQ-mediated interactions and the formation of SDS-resistant mature fibrils. Our data show that αB-c potently inhibits the first stage of ataxin-3 aggregation; however, the second polyQ-dependent stage can still proceed. By using NMR spectroscopy, we have determined that αB-c interacts with an extensive region on the surface of the Josephin domain. These data provide an example of a domain/region flanking an amyloidogenic sequence that has a critical role in modulating aggregation of a polypeptide and plays a role in the interaction with molecular chaperones to prevent this aggregation

Isolation of an Asymmetric RNA Uncoating Intermediate for a Single-Stranded RNA Plant Virus

AbstractWe have determined the three-dimensional structures of both native and expanded forms of turnip crinkle virus (TCV), using cryo-electron microscopy, which allows direct visualization of the encapsidated single-stranded RNA and coat protein (CP) N-terminal regions not seen in the high-resolution X-ray structure of the virion. The expanded form, which is a putative disassembly intermediate during infection, arises from a separation of the capsid-forming domains of the CP subunits. Capsid expansion leads to the formation of pores that could allow exit of the viral RNA. A subset of the CP N-terminal regions becomes proteolytically accessible in the expanded form, although the RNA remains inaccessible to nuclease. Sedimentation velocity assays suggest that the expanded state is metastable and that expansion is not fully reversible. Proteolytically cleaved CP subunits dissociate from the capsid, presumably leading to increased electrostatic repulsion within the viral RNA. Consistent with this idea, electron microscopy images show that proteolysis introduces asymmetry into the TCV capsid and allows initial extrusion of the genome from a defined site. The apparent formation of polysomes in wheat germ extracts suggests that subsequent uncoating is linked to translation. The implication is that the viral RNA and its capsid play multiple roles during primary infections, consistent with ribosome-mediated genome uncoating to avoid host antiviral activity

The Heart of the Matter: The Coaching Model in America's Choice Schools

The Consortium for Policy Research in Education (CPRE) at the University of Pennsylvania was contracted by the National Center on Education and the Economy (NCEE) in 1998 to conduct the external evaluation of the America's Choice school design. CPRE designed and conducted a series of targeted studies on the implementation and impacts of the America's Choice design. This report coincides with the publication of three separate studies by CPRE on the impact of America's Choice in a number of districts across the country using a variety of quantitative and analytic approaches. Those impact analyses and a stand-alone piece on classroom observations conducted in Cohort 4 schools can be viewed as separate pieces or as complements to the information presented in this report. Another recent CPRE publication from fall 2001 is a widely distributed report entitled, Instructional Leadership in a Standards-based Reform, a companion piece to both the impact reports and this report

Millimeter-scale exfoliation of hBN with tunable flake thickness

As a two-dimensional (2D) dielectric material, hexagonal boron nitride (hBN) is in high demand for applications in photonics, nonlinear optics, and nanoelectronics. Unfortunately, the high-throughput preparation of macroscopic-scale, high-quality hBN flakes with controlled thickness is an ongoing challenge, limiting device fabrication and technological integration. Here, we present a metal thin-film exfoliation method to prepare hBN flakes with millimeter-scale dimension, near-unity yields, and tunable flake thickness distribution from 1-7 layers, a substantial improvement over scotch tape exfoliation. The single crystallinity and high quality of the exfoliated hBN are demonstrated with optical microscopy, atomic force microscopy, Raman spectroscopy, and second harmonic generation. We further explore a possible mechanism for the effectiveness and selectivity based on thin-film residual stress measurements, density functional theory calculations, and transmission electron microscopy imaging of the deposited metal films. We find that the magnitude of the residual tensile stress induced by thin film deposition plays a key role in determining exfoliated flake thickness in a manner which closely resembles 3D semiconductor spalling. Lastly, we demonstrate that our exfoliated, large-area hBN flakes can be readily incorporated as encapsulating layers for other 2D monolayers. Altogether, this method brings us one step closer to the high throughput, mass production of hBN-based 2D photonic, optoelectronic, and quantum devices.Comment: 21 pages, 5 figures, work completed at Stanford Universit