Time Required for Gross Examination of Routine Second and Third Trimester Singleton Placentas by Pathologists' Assistants.

INTRODUCTION: In both Canada and the United States, workload measurement for anatomic pathology is mainly based on complexity and clinical significance of specimens, with gross examination being a considerable contributor. While Pathologists' Assistants (PAs) play an increasing role in gross examination, there is little known regarding the time required for PAs to complete grossing tasks. This information is essential for effective staffing and workload management in pathology laboratories. The objective of our study was to determine the time required for PAs to gross second and third trimester singleton placentas in a large tertiary hospital with a significant perinatal pathology service. MATERIALS AND METHODS: For our study, 7 certified PAs each grossed a minimum of 10 second and third trimester singleton placentas using a standard placental grossing protocol, an electronic laboratory information system, and voice recognition dictation software. Placental specimens requiring photography, sampling for ancillary studies, or immediate pathologist's consultation were excluded. We calculated average and standard deviation of grossing times for each PA, overall average grossing time, and 95% confidence interval using a mixed linear regression model. We analyzed the impact of PA job experience, degree obtained, and number of blocks prepared on overall average in a multivariate analysis. RESULTS: The mean grossing times for each PA ranged from 11.0 (standard deviation [sd] = 2.0) to 17.8 (sd = 4.5) minutes. The overall average grossing time was 14.5 minutes, with a 95% confidence interval of 11.7 to 17.3 minutes. In multivariate analysis, an increase in the number of blocks prepared was significantly associated with longer overall average grossing time. If 4 blocks were prepared consistently, the model predicted a slightly lower overall average of 13.3 minutes, with a 95% confidence interval of 10.9 to 15.7 minutes. DISCUSSION: To our knowledge, our study is the first to objectively report time required for PAs to perform gross examinations of routine second and third trimester singleton placentas. The methodology of our study is replicable and can be applied to other specimen types and laboratory settings. Previously, estimated grossing times for specimens were primarily based on retrospective surveys, which were susceptible to recall errors and subjectivity. However, our study demonstrates objective data collection is achievable. Furthermore, the data collected from this study offer valuable insights into the accuracy of previous and current pathology workload models for second and third trimester singleton placentas.

Phase-Selective Solution Synthesis of Perovskite-Related Cesium Cadmium Chloride Nanoparticles.

All-inorganic metal halide perovskite-related phases are semiconducting materials that are of significant interest for a wide range of applications. Nanoparticles of these materials are particularly useful because they permit solution processing while offering unique and tunable properties. Of the many metal halide systems that have been studied extensively, cesium cadmium chlorides remain underexplored, and synthetic routes to access them as nanoscale materials have not been established. Here we demonstrate that a simple solution-phase reaction involving the injection of a cesium oleate solution into a cadmium chloride solution produces three distinct cesium cadmium chlorides: hexagonal CsCdCl3 and the Ruddlesden-Popper layered perovskites Cs2CdCl4 and Cs3Cd2Cl7. The phase-selective synthesis emerges from differences in reagent concentrations, temperature, and injection rates. A key variable is the rate at which the cesium oleate solution is injected into the cadmium chloride solution, which is believed to influence the local Cs:Cd concentration during precipitation, leading to control over the phase that forms. Band structure calculations indicate that hexagonal CsCdCl3 is a direct band gap semiconductor while Cs2CdCl4 and Cs3Cd2Cl7 have indirect band gaps. The experimentally determined band gap values for CsCdCl3, Cs2CdCl4, and Cs3Cd2Cl7 are 5.13, 4.91, and 4.70 eV, respectively, which places them in a rare category of ultrawide-band-gap semiconductors.

Interface-mediated noble metal deposition on transition metal dichalcogenide nanostructures.

Functionalizing the surfaces of transition metal dichalcogenide (TMD) nanosheets with noble metals is important for electrically contacting them to devices, as well as improving their catalytic and sensing capabilities. Solution-phase deposition provides a scalable approach to the creation of metal-TMD hybrid systems, but controlling such processes remains challenging. Here we elucidate the different pathways by which gold and silver deposit at room temperature onto colloidal 1T-WS2, 2H-WS2, 2H-MoSe2, 2H-WSe2, 1T'-MoTe2 and Td-WTe2 few-layer nanostructures to produce several distinct classes of 0D-2D and 2D-2D metal-TMD hybrids. Uniform gold nanoparticles form on all of the TMDs. By contrast, silver deposits as nanoparticles with a bimodal size distribution on the disulfides and diselenides, and as atomically thin layers on the ditellurides. The various sizes and morphologies of these surface-bound metal species arise from the relative strengths of the interfacial metal-chalcogen bonds during the reduction of Au3+ or Ag+ by the TMDs.

Multi-Step Topochemical Pathway to Metastable Mo2AlB2 and Related Two-Dimensional Nanosheet Heterostructures.

The rational synthesis of metastable inorganic solids, which is a grand challenge in solid-state chemistry, requires the development of kinetically controlled reaction pathways. Topotactic strategies can achieve this goal by chemically modifying reactive components of a parent structure under mild conditions to produce a closely related analogue that has otherwise inaccessible structures and/or compositions. Refractory materials, such as transition metal borides, are difficult to structurally manipulate at low temperatures because they generally are chemically inert and held together by strong covalent bonds. Here, we report a multistep low-temperature topotactic pathway to bulk-scale Mo2AlB2, which is a metastable phase that has been predicted to be the precursor needed to access a synthetically elusive family of 2-D metal boride (MBene) nanosheets. Room-temperature chemical deintercalation of Al from the stable compound MoAlB (synthesized as a bulk powder at 1400 °C) formed highly strained and destabilized MoAl1-xB, which was size-selectively precipitated to isolate the most reactive submicron grains and then annealed at 600 °C to deintercalate additional Al and crystallize Mo2AlB2. Further heating resulted in topotactic decomposition into bulk-scale Mo2AlB2-AlOx nanolaminates that contain Mo2AlB2 nanosheets with thickness of 1-3 nm interleaved by 1-3 nm of amorphous aluminum oxide. The combination of chemical destabilization, size-selective precipitation, and low-temperature annealing provides a potentially generalizable kinetic pathway to metastable variants of refractory compounds, including bulk Mo2AlB2 and Mo2AlB2-AlOx nanosheet heterostructures, and opens the door to other previously elusive 2-D materials such as 2-D MoB (MBene).

Defect-mediated selective hydrogenation of nitroarenes on nanostructured WS2.

Transition metal dichalcogenides (TMDs) are well known catalysts as both bulk and nanoscale materials. Two-dimensional (2-D) TMDs, which contain single- and few-layer nanosheets, are increasingly studied as catalytic materials because of their unique thickness-dependent properties and high surface areas. Here, colloidal 2H-WS2 nanostructures are used as a model 2-D TMD system to understand how high catalytic activity and selectivity can be achieved for useful organic transformations. Free-standing, colloidal 2H-WS2 nanostructures containing few-layer nanosheets are shown to catalyze the selective hydrogenation of a broad scope of substituted nitroarenes to their corresponding aniline derivatives in the presence of other reducible functional groups. Microscopic and computational studies reveal the important roles of sulfur vacancy-rich basal planes and tungsten-terminated edges, which are more abundant in nanostructured 2-D materials than in their bulk counterparts, in enabling the functional group selectivity. At tungsten-terminated edges and on regions of the basal planes having high concentrations of sulfur vacancies, vertical adsorption of the nitroarene is favored, thus facilitating hydrogen transfer exclusively to the nitro group due to geometric effects. At lower sulfur vacancy concentrations on the basal planes, parallel adsorption of the nitroarene is favored, and the nitro group is selectively hydrogenated due to a lower kinetic barrier. These mechanistic insights reveal how the various defect structures and configurations on 2-D TMD nanostructures facilitate functional group selectivity through distinct mechanisms that depend upon the adsorption geometry, which may have important implications for the design of new and enhanced 2-D catalytic materials across a potentially broad scope of reactions.

Intermetallic Ni2Ta Electrocatalyst for the Oxygen Evolution Reaction in Highly Acidic Electrolytes.

The identification of materials capable of catalyzing the oxygen evolution reaction (OER) in highly acidic electrolytes is a critical bottleneck in the development of many water-splitting technologies. Bulk-scale solid-state compounds can be readily produced using high-temperature reactions and therefore used to expand the scope of earth-abundant OER catalysts capable of operating under strongly acidic conditions. Here, we show that high temperature arc melting and powder metallurgy reactions can be used to synthesize electrodes consisting of intermetallic Ni2Ta that can catalyze the OER in 0.50 M H2SO4. Arc melted Ni2Ta electrodes evolve oxygen at a current density of 10 mA/cm2 for >66 h with corrosion rates 2 orders of magnitude lower than that of pure Ni. The overpotential required for pellets of polycrystalline Ni2Ta to produce a current density of 10 mA/cm2 is 570 mV. This strategy can be generalized to include other first-row transition metals, including intermetallic Fe2Ta and Co2Ta systems.

General Strategy for the Synthesis of Transition Metal Phosphide Films for Electrocatalytic Hydrogen and Oxygen Evolution.

Transition metal phosphides recently have been identified as promising Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we present a general and scalable strategy for the synthesis of transition metal phosphide electrodes based on the reaction of commercially available metal foils (Fe, Co, Ni, Cu, and NiFe) with various organophosphine reagents. The resulting phosphide electrodes were found to exhibit excellent electrocatalytic HER and OER performance. The most active electrodes required overpotentials of only -128 mV for the HER in acid (Ni2P), -183 mV for the HER in base (Ni2P), and 277 mV for the OER in base (NiFeP) to produce operationally relevant current densities of 10 mA cm(-2). Such HER and OER performance compares favorably with samples prepared using significantly more elaborate and costly procedures. Furthermore, we demonstrate that the approach can also be utilized to obtain highly active and conformal metal phosphide coatings on photocathode materials, such as highly doped Si, that are relevant to solar fuels production.