Transport of microsporidium Encephalitozoon intestinales spores in sandy porous media

The retention and transport of microsporidium Encephalitozoon intestinales spores in two water-saturated sandy porous media was investigated in this study. The initial breakthrough of the spores in the column effluent occurred essentially simultaneously with that of a non-reactive tracer, indicating no significant velocity enhancement. A large fraction (45-73%) of the spores injected into the columns was not recovered in the effluent, indicating removal from solution through colloid retention processes of attachment and/or straining. The relative significance of attachment and straining to total retention was evaluated in additional experiments. An experiment was conducted with a sieved coarse fraction of porous media for which straining is unlikely to be of significance based on the relative diameters of the spores and porous-medium pores. The spore recovery for this experiment was similar to the recoveries obtained for microsporidia transport in the un-sieved parent porous medium. An additional experiment was conducted with a subsample of the coarse fraction that was acid-washed to reduce potential surface attachment sites. Spore recovery was complete for this experiment. These results suggest surface deposition was the primary removal mechanism in our system. This conclusion is supported by the results of an experiment wherein deionized water was flushed through a column that was previously flushed with electrolyte solution. The effluent spore concentrations were observed to increase upon injection of deionized water, indicating re-mobilization of spores upon a change in water chemistry. The measured data were successfully simulated using a mathematical model incorporating colloid filtration. The results of this study suggest that the transport of microspordia in sandy porous media is governed by established colloid-transport processes.     

对家庭自营企业负面影响的探讨

对于第三世界城市中的家庭而言，家庭自营企业是一种必要的缓解贫困的对策。本文使用的数据来自英国国际开发部资助的关于4个国家的家庭自营企业(HBEs)比较研究报告，从中总结了若干定量数据和定性数据作为补充，由此证明许多有关禁止在家庭内部办生产性企业的政策是基于对HBEs本质的误解。政府应采取机动灵活的干预政策来扶持HBEs，同时解决他们造成的若干问题。     

The Control of Shrinkage and Thermal Instability in SU‐8 Photoresists for Holographic Lithography

The negative‐tone epoxy photoresist, SU‐8, expands ≈1% by volume after postexposure baking. However, if the maximum optical fluence is comparable to that at the insolubility threshold, as in a holographic exposure, the developed resist shrinks (≈35% by volume) due to the removal of light oligomers not incorporated into the polymeric network. IR spectroscopy shows that, at this level of exposure, only 15% of the epoxy groups in the insoluble polymer have reacted; consequently microstructural elements soften and collapse at >100 °C. When the light oligomers are removed, the sensitivity of the resist is unchanged, provided that 5% (w/w) of a high‐molecular‐weight reactive plasticizer (glycidoxy‐terminated polyethylene glycol) is added, but it shrinks less on development and, when used as a photonic crystal template, shows improved uniformity with less cracking and buckling. Reinforcing the polymer network by reaction with the polyfunctional amine (bis‐N,N′‐(3‐aminopropyl)ethylenediamine) increases the extent of cross‐linking and the thermal stability, allowing inverse replicas of photonic crystal templates to be fabricated from both Al:ZnO and Zr₃N₄ using atomic layer deposition at temperatures up to 200 °C.     

Hydrogen storage in dinuclear Pt(II) metallacycles

Hydrogen gas physisorption in two distinct dinuclear Pt(II) metallacycles was investigated with ²H nuclear magnetic resonance (NMR) spectroscopy. Hydrogen adsorption isotherm data and ²H NMR spectroscopy indicated that hydrogen storage occurs via condensation within the cavities of one of the macrocycles and at the interstitial sites in the other. In addition, this study further supports the notion that heat of adsorption and pore size play critical roles in hydrogen storage.     

Carbide Precipitation in 2.25 Cr-1 Mo Bainitic Steel: Effect of Heating and Isothermal Tempering Conditions

The effect of the tempering heat treatment, including heating prior to the isothermal step, on carbide precipitation has been determined in a 2.25 Cr-1 Mo bainitic steel for thick-walled applications. The carbides were identified using their amount of metallic elements, morphology, nucleation sites, and diffraction patterns. The evolution of carbide phase fraction, morphology, and composition was investigated using transmission electron microscopy, X-ray diffraction, as well as thermodynamic calculations. Upon heating, retained austenite into the as-quenched material decomposes into ferrite and cementite. M₇C₃ carbides then nucleate at the interface between the cementite and the matrix, triggering the dissolution of cementite. M₂C carbides precipitate separately within the bainitic laths during slow heating. M₂₃C₆ carbides precipitate at the interfaces (lath boundaries or prior austenite grain boundaries) and grow by attracting nearby chromium atoms, which results in the dissolution of M₇C₃ and, depending on the temperature, coarsening, or dissolution of M₂C carbides, respectively.     

The value of technological advance in decarbonizing the U.S. economy

This paper examines the role of technology in managing the costs of a carbon constraint on the U.S. economy. Two portfolios of technology are examined. One reflects modest investments in climate-friendly technologies, the other more aggressive development. The analysis indicates that the development of a broad range of low- to zero-carbon emitting technologies can substantially reduce (but not eliminate) the economic cost of decarbonization. By enabling large-scale emission reductions on the supply-side, costly reductions in demand are avoided. In particular, the emergence of electricity as a low-carbon fuel provides a powerful lever for achieving reductions in other sectors of the economy at lower cost. While the analysis suggests that there is no “free lunch,” the bill, which may indeed be well worth paying, can be greatly reduced through an accelerated R&D program and successful diffusion of new technology throughout the economy.     

Specific sleepiness symptoms are indicators of performance impairment during sleep deprivation

Drivers are not always aware that they are becoming impaired as a result of sleepiness. Using specific symptoms of sleepiness might assist with recognition of drowsiness related impairment and help drivers judge whether they are safe to drive a vehicle, however this has not been evaluated. In this study, 20 healthy volunteer professional drivers completed two randomized sessions in the laboratory – one under 24 h of acute sleep deprivation, and one with alcohol. The Psychomotor Vigilance Task (PVT) and a 30 min simulated driving task (AusEdTM) were performed every 3–4 h in the sleep deprivation session, and at a BAC of 0.00% and 0.05% in the alcohol session, while electroencephalography (EEG) and eye movements were recorded. After each test session, drivers completed the Karolinska Sleepiness Scale (KSS) and the Sleepiness Symptoms Questionnaire (SSQ), which includes eight specific sleepiness and driving performance symptoms. A second baseline session was completed on a separate day by the professional drivers and in an additional 20 non-professional drivers for test–retest reliability. There was moderate test–retest agreement on the SSQ (r = 0.59). Significant correlations were identified between individual sleepiness symptoms and the KSS score (r values 0.50–0.74, p < 0.01 for all symptoms). The frequency of all SSQ items increased during sleep deprivation (χ² values of 28.4–80.2, p < 0.01 for all symptoms) and symptoms were related to increased subjective sleepiness and performance deterioration. The symptoms “struggling to keep your eyes open”, “difficulty maintaining correct speed”, “reactions were slow” and “head dropping down” were most closely related to increased alpha and theta activity on EEG (r values 0.49–0.59, p < 0.001) and “nodding off to sleep” and “struggling to keep your eyes open” were related to slow eye movements (r values 0.67 and 0.64, p < 0.001). Symptoms related to visual disturbance and impaired driving performance were most accurate at detecting severely impaired driving performance (AUC on ROC curve of 0.86–0.91 for detecting change in lateral lane position greater than the change at a BAC of 0.05%). Individual sleepiness symptoms are related to impairment during acute sleep deprivation and might be able to assist drivers in recognizing their own sleepiness and ability to drive safely.