Cellaca® PLX image cytometer as an alternative for immunophenotyping, GFP/RFP transfection efficiencies, and apoptosis analysis.

Cell and gene therapy is a fast-growing field for cancer therapeutics requiring reliable instrumentation and technologies. Key parameters essential for satisfying Chemistry Manufacturing and Controls criteria standards are routinely performed using flow cytometry. Recently, image cytometry was developed for cell characterization and cell-based assays but had not yet demonstrated sufficient sensitivity for surface marker detection. We developed the Cellaca® PLX image cytometry system and the respective methodologies required for immunophenotyping, GFP and RFP transfection/transduction efficiencies, and cell health analyses for routine cell characterization. All samples tested were compared directly to results from the CytoFLEX flow cytometer. PBMCs were stained with T-cell surface markers for immunophenotyping, and results show highly comparable CD3, CD4, and CD8 populations (within 5 %). GFP- or RFP-expressing cell lines were analyzed for transfection/transduction efficiencies, and the percentage positive cells and respective viabilities were equivalent on both systems. Staurosporine-treated Jurkat cells were stained for apoptotic markers, where annexin V and caspase-3 positive cells were within 5 % comparing both instruments. The proposed system may provide a complementary tool for performing routine cell-based experiments with improved efficiency and sensitivity compared to prior image cytometers, which may be significantly valuable to the cell and gene therapy field.

Mean Free Path Suppression of Low-Frequency Phonons in SiGe Nanowires.

Accurate measurements of the size-dependent lattice thermal conductivity (κl) of alloy nanostructures are challenging but help to address outstanding questions on the effects of atomic disorder and surface roughness on low-frequency vibrational modes in functional materials. Here, we report sensitive κl measurements of multiple segments of the same individual SiGe nanowires. In contrast to a previous report of ballistic thermal transport over several microns in SiGe nanowires, the obtained κl are nearly independent of the segment length from 2 to 10 µm and the temperature between 150 and 300 K. The results are in agreement with a theoretical calculation based on the virtual crystal approximation of the vibrational modes as phonons with mean free paths suppressed by purely diffuse surface scattering. The findings inform continuing theoretical efforts for understanding the roles of different types of vibrational modes in thermal transport in disordered thermoelectric and electronic materials.

Modifying the thermal conductivity of small molecule organic semiconductor thin films with metal nanoparticles.

Thermal properties of organic semiconductors play a significant role in the performance and lifetime of organic electronic devices, especially for scaled-up large area applications. Here we employ silver nanoparticles (Ag NPs) to modify the thermal conductivity of the small molecule organic semiconductor, dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT). The differential 3-ω method was used to measure the thermal conductivity of Ag-DNTT hybrid thin films. We find that the thermal conductivity of pure DNTT thin films do not vary with the deposition temperature over a range spanning 24 °C to 80 °C. The thermal conductivity of the Ag-DNTT hybrid thin film initially decreases and then increases when the Ag volume fraction increases from 0% to 32%. By applying the effective medium approximation to fit the experimental results of thermal conductivity, the extracted thermal boundary resistance of the Ag-DNTT interface is 1.14 ± 0.98 × 10(-7) m(2)-K/W. Finite element simulations of thermal conductivity for realistic film morphologies show good agreement with experimental results and effective medium approximations.

Microsecond-sustained lasing from colloidal quantum dot solids.

Colloidal quantum dots have grown in interest as materials for light amplification and lasing in view of their bright photoluminescence, convenient solution processing and size-controlled spectral tunability. To date, lasing in colloidal quantum dot solids has been limited to the nanosecond temporal regime, curtailing their application in systems that require more sustained emission. Here we find that the chief cause of nanosecond-only operation has been thermal runaway: the combination of rapid heat injection from the pump source, poor heat removal and a highly temperature-dependent threshold. We show microsecond-sustained lasing, achieved by placing ultra-compact colloidal quantum dot films on a thermally conductive substrate, the combination of which minimizes heat accumulation. Specifically, we employ inorganic-halide-capped quantum dots that exhibit high modal gain (1,200 cm(-1)) and an ultralow amplified spontaneous emission threshold (average peak power of ∼50 kW cm(-2)) and rely on an optical structure that dissipates heat while offering minimal modal loss.

The effect of a voice assist manikin (VAM) system on CPR quality among prehospital providers.

UNLABELLED: Numerous studies have documented poor cardiopulmonary resuscitation (CPR) performance among prehospital providers during both simulated and actual resuscitations. Previous studies have shown that a real-time, voice assist manikin (VAM) system may improve CPR performance. OBJECTIVE: To determine whether VAM prompting would improve CPR performance by prehospital providers during simulated resuscitation. METHODS: In this prospective, randomized, crossover design, 114 prehospital providers performed two 3-minute sessions of one-rescuer CPR on a VAM-resuscitation manikin: one round with the VAM feature turned on and one with the feature turned off. The primary outcomes were measured at 15-second intervals and included the fraction of correct compressions, the mean compression depth, the fraction of correct ventilations, and the mean ventilation tidal volume. Generalized estimating equations were used to analyze the repeated measures. RESULTS: The VAM prompting was not directly associated with correct compressions during one-rescuer CPR in a cohort of subjects naïve to the system. However, the general decay in correct compressions seen over 3 minutes was attenuated with VAM prompting. Neither the compression depth nor the decay in compression depth over time was affected by VAM prompting. In contrast, VAM prompting did affect the fraction of correct ventilations and attenuated the time-dependent decline in correct ventilations in tidal volume. CONCLUSIONS: Use of VAM did not directly improve compression or ventilation rate or quality in this cohort of prehospital providers. However, use of VAM did prevent decay of compression and ventilation performance over time.