ALBERT

Description: Background: Workers chronically exposed to manganese in welding fumes may develop an extra-pyramidal syndrome with postural and action tremors. Objectives: To determine the utility of tremor analysis in distinguishing tremors among workers exposed to welding fumes, patients with Idiopathic Parkinson’s Disease (IPD) and Essential Tremor (ET). Methods: Retrospective study of recorded tremor in subjects from academic Movement Disorders Clinics and Welders. Quantitative tremor analysis was performed and associated with clinical status. Results: Postural tremor intensity was increased in Welders and ET and was associated with visibly greater amplitude of tremor with arms extended. Mean center frequencies (Cf) of welders and patients with ET were significantly higher than the mean Cf of PD subjects. Although both the welders and the ET group exhibited a higher Cf with arms extended, welders could be distinguished from the ET subjects by a significantly lower Cf of the rest tremor than that measured in ET subjects. Conclusions: In the context of an appropriate exposure history and neurological examination, tremor analysis may be useful in the diagnosis of manganese-related extra-pyramidal manifestations.

Description: Abstract Using molten‐salt synthetic techniques, NaNbO3 (Space group Pbcm; No. 57) was prepared in high purity at a reaction time of 12 hours and a temperature of 900 °C. All NaNbO3 products were prepared from stoichiometric ratios of Nb2O5 and Na2CO3 together with the addition of a salt flux introduced at a 10:1 molar ratio of salt‐to NaNbO3, i.e., using the Na2SO4, NaF, NaCl, and NaBr salts. A solid‐state synthesis was performed in the absence of a molten salt to serve as a control. The reaction products were all found to be phase pure through powder X‐ray diffraction (PXRD), e.g., with refined lattice constants of a = 5.512(5)Å, b = 5.567(3)Å and c = 15.516(8)Å from the Na2SO4 salt reaction. The products were characterized using UV‐vis diffuse reflectance spectroscopy to have a bandgap size of ~3.5 eV. The particles sizes were analyzed by scanning electron microscopy (SEM) and found to be dependent upon the flux type, from ~〈1μm to 〉10μm in length, with overall surface areas that could be varied from 0.66 m2 g−1 (for NaF) to 1.55 m2 g−1 (for NaBr). Cubic‐shaped particle morphologies were observed for the metal‐halide salts with the set of exposed (100)/(010)/(001) crystal facets, while a truncated octahedral morphology formed in the sodium‐sulfate salt reaction with predominantly the set of (110)/(101)/(011) crystal facets. The products were found to be photocatalytically‐active for hydrogen production under UV‐Vis irradiation, with the aid of a 1 wt% Pt surface cocatalyst. The platinized NaNbO3 particles were suspended in an aqueous 20% methanol solution and irradiated by UV‐vis light (λ 〉 230 nm). After 6 hours of irradiation, the average total hydrogen production varied with the particle morphologies and sizes, with 753 μmol for Na2SO4, 334 μmol for NaF, 290 μmol for NaCl, 81 μmol for NaBr, and 249 μmol for the solid‐state synthesized NaNbO3. These trends show a clear relationship to particle sizes, with smaller particles showing higher photocatalytic activity in the order of NaF 〉 NaCl 〉 NaBr. Further, the particle morphologies obtained from the Na2SO4 flux showed even higher photocatalytic activity, though having a relatively similar overall surface area, owing to the higher activity of the (110) crystal faces. The apparent quantum yield (100 mW cm−2, λ = 230 to 350 nm, pH = 7) measured at 3.7% for NaNbO3 prepared using the NaF flux, but this was doubled to 6.8% when prepared using the Na2SO4 flux. Thus, these results demonstrate the powerful utility of flux synthetic techniques to control particle sizes and to expose higher‐activity crystal facets to boost their photocatalytic activities for molecular hydrogen production. This article is protected by copyright. All rights reserved.

Description: The pervasive shock response spectrum (SRS) and damage boundary methods for evaluating product fragility and designing external cushioning for shock protection are described in detail with references to the best available literature. Underlying assumptions are carefully reviewed and the central message of the SRS is highlighted, particularly as it relates to standardized drop testing. Shortcomings of these methods are discussed, and the results are extended to apply to more general systems. Finally some general packaging and shock-mounting strategies are discussed in the context of protecting a fragile disk drive in a notebook computer, although the conclusions apply to other products as well. For example, exterior only cushioning (with low restitution to reduce subsequent impacts) will provide a slenderer form factor than the next best strategy: interior cushioning with a “dead” hard outer shell.