Preliminary experiments on keyboard design for semiautomatic mail sorting.

Mail sorting by keyboards will require operatives either to remember digitation for each address (memory encoding) or key certain selected characters from the address (extraction encoding). Keyboards may be chord (multiple depressions per stroke) or sequential (single keys in succession), 3 preliminary experiments indicated (a) in sequential keying a key stroke takes approximately 0.3 sec., hence keyboards with many keys and requiring few key strokes per encoding are preferable; (b) for memory encoding a chord keyboard with many keys (24) is superior to a smaller chord keyboard and a sequential keyboard, (c) for extraction encoding a typewriter and a 24-key chord keyboard are equal in performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization and control of plastic deformation in mesoscale premolded components to realize in‐mold assembled mesoscale revolute joints

This article reports a mold design strategy and a detailed mechanics‐based modeling approach to characterize and control the plastic deformation of premolded components during in‐mold assembly of mesoscale revolute joints. The following new results are reported in this article. First, a mesoscale mold design with varying cavity shape is described to perform in‐mold assembly of the mesoscale revolute joint. Second, a transient computational fluid dynamics (CFD) modeling approach to determine the forces experienced by the mesoscale parts due to injection molding is described. Finally, a mechanics‐based model approach developed using a combination of experimental materials property data and the CFD results as input to a finite element simulation of the deformation response of the mesoscale part is presented for the determination of critical mold design parameters that are necessary for repeatable fabrication of articulating mesoscale revolute joints. Using the advances reported in this article a mesoscale revolute joint has been successfully molded. To the best of our knowledge, this is the first demonstration of in‐mold assembly process using a varying cavity shape mold tocreate an articulating mesoscale revolute joint. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

An investigation of the aerodynamic admittances and aerodynamic weighting functions of trains

Increasing train speeds combined with the predicted reduction in the weight of new trains ensure that the effect of crosswinds on train stability is of continued interest to the rail industry. Changes in the approaching wind velocity can in turn lead to changes in both the lift and side force on a vehicle. Calculations of the wind induced force can either be undertaken in the frequency domain with knowledge of aerodynamic admittance characteristics or in the time domain using aerodynamic weighting functions. This paper investigates the applicability of developing a universal aerodynamic admittance function and a corresponding analytical weighting function for a variety of train types based on a range of experimental data. It is suggested that only two variables are required to parameterise both the admittance and weighting functions. It is also argued that for certain train types one of these variables can be considered as a constant across a wide range of yaw angles.     

Measuring gas hold-up in gas–liquid/gas–solid–liquid stirred tanks with an electrical resistance tomography linear probe

An electrical resistance tomography (ERT) linear probe was used to measure gas hold-up in a two-phase (gas–liquid) and three phase (gas–solid–liquid) stirred-tank system equipped with a Rushton turbine. The ERT linear probe was chosen rather than the more commonly used ring cage geometry to achieve higher resolution in the axial direction as well as its potential for use on manufacturing plant. Gas-phase distribution was measured as a function of flow regime by varying both impeller speed and gas flow rate. Global and local gas hold-up values were calculated using ERT data by applying Maxwell's equation for conduction through heterogeneous media. The results were compared with correlations, hard-field tomography data, and computational fluid dynamic simulations available in the literature, showing good agreement. This study thus demonstrates the capability of ERT using a linear probe to offer, besides qualitative tomographic images, reliable quantitative data regarding phase distribution in gas–liquid systems.     

Real-time cellular uptake of serotonin using fluorescence lifetime imaging with two-photon excitation

The real-time uptake of serotonin, a neurotransmitter, by rat leukemia mast cell line RBL-2H3 and 5-hydroxytryptophan by Chinese hamster V79 cells has been studied by fluorescence lifetime imaging microscopy (FLIM), monitoring ultraviolet (340 nm) fluorescence induced by two-photon subpicosecond 630 nm excitation. Comparison with two-photon excitation with 590 nm photons or by three-photon excitation at 740 nm shows that the use of 630 nm excitation provides optimal signal intensity and lowered background from auto-fluorescence of other cellular components. In intact cells, we observe using FLIM three distinct fluorescence lifetimes of serotonin and 5-hydroxytryptophan according to location. The normal fluorescence lifetimes of both serotonin (3.8 ns) and 5-hydroxytryptophan (3.5 ns) in solution are reduced to approximately 2.5 ns immediately on uptake into the cell cytosol. The lifetime of internalized serotonin in RBL-2H3 cells is further reduced to approximately 2.0 ns when stored within secretory vesicles.     

Implementation of design of experiments approach for the micronization of a drug with a high brittle–ductile transition particle diameter

Objective: To optimize air-jet milling conditions of ibuprofen (IBU) using design of experiment (DoE) method, and to test the generalizability of the optimized conditions for the processing of another non-steroidal anti-inflammatory drug (NSAID).

Methods: Bulk IBU was micronized using an Aljet mill according to a circumscribed central composite (CCC) design with grinding and pushing nozzle pressures (GrindP, PushP) varying from 20 to 110?psi. Output variables included yield and particle diameters at the 50th and 90th percentile (D₅₀, D₉₀). Following data analysis, the optimized conditions were identified and tested to produce IBU particles with a minimum size and an acceptable yield. Finally, indomethacin (IND) was milled using the optimized conditions as well as the control.

Results: CCC design included eight successful runs for milling IBU from the ten total runs due to powder “blowback” from the feed hopper. DoE analysis allowed the optimization of the GrindP and PushP at 75 and 65?psi. In subsequent validation experiments using the optimized conditions, the experimental D₅₀ and D₉₀ values (1.9 and 3.6?μm) corresponded closely with the DoE modeling predicted values. Additionally, the optimized conditions were superior over the control conditions for the micronization of IND where smaller D₅₀ and D₉₀ values (1.2 and 2.7?μm vs. 1.8 and 4.4?μm) were produced.

Conclusion: The optimization of a single-step air-jet milling of IBU using the DoE approach elucidated the optimal milling conditions, which were used to micronize IND using the optimized milling conditions.     

Highly Efficient Perovskite–Perovskite Tandem Solar Cells Reaching 80% of the Theoretical Limit in Photovoltage

Organic–inorganic hybrid perovskite multijunction solar cells have immense potential to realize power conversion efficiencies (PCEs) beyond the Shockley–Queisser limit of single‐junction solar cells; however, they are limited by large nonideal photovoltage loss (V _oc,loss) in small‐ and large‐bandgap subcells. Here, an integrated approach is utilized to improve the V _oc of subcells with optimized bandgaps and fabricate perovskite–perovskite tandem solar cells with small V _oc,loss. A fullerene variant, Indene‐C₆₀ bis‐adduct, is used to achieve optimized interfacial contact in a small‐bandgap (≈1.2 eV) subcell, which facilitates higher quasi‐Fermi level splitting, reduces nonradiative recombination, alleviates hysteresis instabilities, and improves V _oc to 0.84 V. Compositional engineering of large‐bandgap (≈1.8 eV) perovskite is employed to realize a subcell with a transparent top electrode and photostabilized V _oc of 1.22 V. The resultant monolithic perovskite–perovskite tandem solar cell shows a high V _oc of 1.98 V (approaching 80% of the theoretical limit) and a stabilized PCE of 18.5%. The significantly minimized nonideal V _oc,loss is better than state‐of‐the‐art silicon–perovskite tandem solar cells, which highlights the prospects of using perovskite–perovskite tandems for solar‐energy generation. It also unlocks opportunities for solar water splitting using hybrid perovskites with solar‐to‐hydrogen efficiencies beyond 15%.     

Achieving Biocompatible SABRE: An in vitro Cytotoxicity Study

Production of a biocompatible hyperpolarized bolus for signal amplification by reversible exchange (SABRE) could open the door to simple clinical diagnosis via magnetic resonance imaging. Essential to successful progression to preclinical/clinical applications is the determination of the toxicology profile of the SABRE reaction mixture. Herein, we exemplify the cytotoxicity of the SABRE approach using in vitro cell assays. We conclude that the main cause of the observed toxicity is due to the SABRE catalyst. We therefore illustrate two catalyst removal methods: one involving deactivation and ion‐exchange chromatography, and the second using biphasic catalysis. These routes produce a bolus suitable for future in vivo study.     

Differential Effects of Estrogen and Progestin on Apolipoprotein B100 and B48 Kinetics in Postmenopausal Women

The distinct effects of the estrogen and progestin components of hormonal therapy on the metabolism of apolipoprotein (apo) B‐containing lipoproteins have not been studied. We enrolled eight healthy postmenopausal women in a placebo‐controlled, randomized, double‐blind crossover study. Each subject received placebo, conjugated equine estrogen (CEE, 0.625 mg/day) and CEE plus medroxyprogesterone acetate (MPA, 2.5 mg/day) for 8 weeks in a randomized order, with a 4‐week washout between phases. Main outcomes were the fractional catabolic rate (FCR) and production rate (PR) of apo B100 in triglyceride‐rich lipoproteins (TRL), intermediate‐density lipoproteins (IDL) and low ‐density lipoprotein (LDL) and of apo B48 in TRL. Compared to placebo, CEE increased TRL apo B100 PR (p = 0.04). CEE also increased LDL apo B100 FCR (p = 0.02), but this effect was offset by a significant increase in LDL apo B100 PR (p = 0.04). Adding MPA to CEE negated the CEE effects resulting in no significant changes in TRL apo B100 PR and LDL apo B100 FCR and PR relative to placebo. Relative to placebo, during CEE there was a trend toward a reduction in plasma apo B48 concentrations and PR (p = 0.07 and p = 0.12, respectively). Compared with CEE, CEE + MPA significantly increased TRL apo B48 FCR (p = 0.02) as well as apo B48 PR (p = 0.01), resulting in no significant changes in apo B48 concentration. Estrogen and progestin have independent and opposing effects on the metabolism of the atherogenic apo B100‐ and apo B48‐containing lipoproteins.