The future of crystalline silicon technology in the US Department of Energy program

Two basic findings were presented in the outlined report. The first is that silicon has a very high potential efficiency, demonstrated improvement in reliability and a significant potential for cost reductions. The second is that the photovoltaic technology development process is highly uncertain, but crystalline silicon technology has a substantial knowledge base to draw from, improving its chances of success. Several issues to be addressed are outlined

Conformations Of A Model Protein Revealed By An Aggregating Cuᴵᴵ Porphyrin: Sensing The Difference

Aggregated t-CuP binds to poly-L-glutamate through supramolecular interactions, revealing itself to be an extremely sensitive probe for the major conformations of the polymeric scaffold

Effect Of Zinc Cations On The Kinetics Of Supramolecular Assembly And The Chirality Of Porphyrin J-Aggregates

Dilute aqueous solutions of anionic meso-4-sulfonatophenyl-porphyrin (TPPS) extract zinc(ii) ions from glass or quartz surfaces at room temperature and efficiently form the corresponding metal complex (ZnTPPS). The partial or complete formation of ZnTPPS has been probed by UV/Vis spectroscopy and both static and time-resolved fluorescence. The source of zinc(ii) ions has been clearly identified through inductively coupled plasma optical emission spectrometry. The presence of increasing amounts of ZnTPPS slows down the rate of TPPS J-aggregate formation in acid solution. This influences the nucleation step and has a profound impact on the onset of chirality in these species. This evidence indicates the important role of this adventitious metal ion in the interpretation of various spectroscopic and kinetic data for the self-assembly of the TPPS porphyrin and provides some insights into controversial findings on their chirality. The use of this metal derivative as the starting compound for in situ formation of monomeric TPPS is suggested

Management and radiographic outcomes of femoral head fractures.

BackgroundFemoral head fractures are uncommon injuries. Small series constitute the majority of the available literature. Surgical approach and fracture management is variable. The purpose of this study was to evaluate the incidence, method of treatment, and outcomes of consecutive femoral head fractures at a regional academic Level I trauma center.Materials and methodsA retrospective review of a prospective database was performed over a 13-year period. All AO/OTA 31C femoral head fractures were identified. A surgical approach and fixation method was recorded. Clinical and radiographic evaluation was performed for patients with 6 months or greater follow-up. Radiographs were evaluated for fixation failure, heterotopic ossification (HO), avascular necrosis (AVN) and post-traumatic arthritis.ResultsWe identified 164 fractures in 163 patients; 147 fractures were available for review. Treatment was operative reduction and internal fixation (ORIF) in 78 (53.1%), fragment excision in 37 (25.1%) and non-operative in 28 (19%). An anterior approach and mini-fragment screws were used in the majority of patients treated with fixation. Sixty-nine fractures had follow-up greater than 6 months. Sixty-two fractures (89.9%) proceeded to uneventful union. All Pipkin III fractures failed operative fixation. Six patients developed AVN, seven patients had a known conversion to hip arthroplasty; HO developed in 28 (40.6%) patients and rarely required excision.ConclusionsFractures of the femoral head are rare. An anterior approach can be used for fragment excision or fixation using mini-fragment screws. Pipkin III fractures represent catastrophic injuries. Non-bridging, asymptomatic HO is common. AVN and posttraumatic degenerative disease of the hip occur but are uncommon.Level of evidenceIV-prognostic

The true systematic status of Liolaemus misleali Donoso Barros and Cei, 1971, from Northern Patagonia, Argentina (Reptilia, Iguanidae)

The taxonomic status of the poorly known Patagonian Lizard Liolaemus ruizleali has been revised according to its only extant holotype and paratypes. It is a composite species: the holotype and two paratypes belong to Liolaemus rothi Koslowsky, 1898, the other four paratypes to Liolaemus kingi somuncurae Cei and Scolaro, 1981. The synonymic list of these latter species is readjusted.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse

The true systematic status of Liolaemus misleali Donoso Barros and Cei, 1971, from Northern Patagonia, Argentina (Reptilia, Iguanidae)

The taxonomic status of the poorly known Patagonian Lizard Liolaemus ruizleali has been revised according to its only extant holotype and paratypes. It is a composite species: the holotype and two paratypes belong to Liolaemus rothi Koslowsky, 1898, the other four paratypes to Liolaemus kingi somuncurae Cei and Scolaro, 1981. The synonymic list of these latter species is readjusted.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse

A new species of the Patagonian Genus Vilcunia, with remarks on its morphology, ecology and distribution

A new species of the genus Vilcunia from near Lago Belgrano, 47°50' South latitude, Santa Cruz, Argentina, is described. The morphology of the new species, V. periglacialis sp. nov. and the closely related V. silvanao are compared and a redescription of V. silvanae is made. Both species are of biogeographical interest given their distribution in the basaltic mesetas of the slopes of the Patagonian Andes.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse

Mechanism For Copper(II)-Mediated Disaggregation Of A Porphyrin J-Aggregate

J-aggregates of anionic meso-tetrakis(4-sulfonatophenyl)porphyrin form at intermediate pH (2.3–3.1) in the presence of NiSO₄ or ZnSO₄ (ionic strength, I.S. = 3.2 M). These aggregates convert to monomeric porphyrin units via metallation with copper(II) ions. The kinetics for the disassembly process, as monitored by UV/vis spectroscopy, exhibits zeroth-order behavior. The observed zeroth-order rate constants show a two-term dependence on copper(II) ion concentrations: linear and second order. Also observed is an inverse dependence on hydrogen ion concentration. Activation parameters have been determined for the disassembly process leading to ΔH^≠ = (+163 ± 15) kJ·mol⁻¹ and ΔS^≠ = (+136 ± 11) J·K⁻¹. A mechanism is proposed in which copper(II) cation is in pre-equilibrium with a reactive site at the rim of the J-aggregate. An intermediate copper species is thus formed that eventually leads to the final metallated porphyrin either through an assisted attack of a second metal ion or through a direct insertion of the metal cation into the macrocycle core