Particle formation from droplet containing nanoparticles: Internal bubble growth

ABSTRACT

Modeling spray drying is based on the behavior of individual droplets involved in the process. The drying history of single droplets is generalized to the entire spray by incorporating drying kinetics equations into Euler–Lagrange models of spray drying process. The morphological evolution of single droplet is determined by parameters of the drying agent and properties of solid material in the droplet. In this study, the possible causes for bubble inception are discussed and different morphological evolutions and deformations are examined. A novel mathematical model of single droplet containing insoluble nanoscale particles and internal bubble has been developed and parametrically studied.     

Distribution profiles of endocrine disrupting PAHs/APEOs in river sediments: is there a potential ecotoxicological problem?

The endocrinic/mutagenic potencies of the endocrine disrupting chemicals (EDCs) polycyclic aromatic hydrocarbons (PAHs), alkylphyenol ethoxylates (APEOs) and their metabolites are well documented. Less so is the endocrinic ecotoxicological/health risk potential of these persistent organic pollutants (POPs) in river sediments. From approximately 5 x 10(8) m3/y of sewage produced in Israel, approximately 70% are reused, mainly in agriculture, following a conventional activated sludge treatment (AST). A major related question is: does this practice conform to sustainability? We have found the APEOs concentration profiles of Israel's rivers/streams, Mediterranean Sea coastal water and groundwater, to be 12.5-74.6, 4.5-25.0 and trace-20.2 microg/L, respectively. In two "representative" rivers, in the central coastal region of the country, the total concentrations of the PAHs and APEOs were found to be (in the upper layers of their sediments) 1.02-1.59, 1.78-2.30, 1.48-3.12 and 31.27-376.23, 2.40-91.70, 62.99-63.63 microg/g, respectively. The distribution of the PAHs in the co-presence of APEOs in rivers and their sediments, can be rationalized in terms of the hydrophobicity/nonbiodegradability of the former and the hydrophilicity-CMC/nonbiodegradability of the latter. Based on (a) the zebrafish egg production test (ZFEPT) - a long-term exposure of zebrafish to actually found environmental concentrations of EDCs; and (b) the low effectiveness of POPs removal in AST, our preliminary conclusions are that (1) there is a potential ecotoxicological/health risk problem; and (2) the practice of conventional wastewater treatment plants (WWTPs)-treated water reuse is incompatible with sustainability.     

Determination of band offsets in heterostructured colloidal nanorods using scanning tunneling spectroscopy

The ability to tailor the properties of semiconductor nanocrystals through creating core/shell heterostructures is the cornerstone for their diverse application in nanotechnology. The band-offsets between the heterostructure components are determining parameters for their optoelectronic properties, dictating for example the degree of charge-carrier separation and localization. So far, however, no method was reported for direct measurement of these factors in colloidal nanocrystals and only indirect information could be derived from optical measurements. Here we demonstrate that scanning tunneling spectroscopy along with theoretical modeling can be used to determine band-offsets in such nanostructures. Applying this approach to CdSe/CdS quantum-dot/nanorod core/shell nanocrystals portrays its type I band structure where both the hole and electron ground state are localized in the CdSe core, in contrast to previous reports which predicted electron delocalization. The generality of the approach is further demonstrated in ZnSe/CdS nanocrystals where their type II band alignment, leading to electron-hole separation, is manifested.     

A two-state electronic antigen and an antibody selected to discriminate between these states

Inspired by biology where pathways are triggered and suppressed by specific binding of two molecules, we realize a functional interface between electronics and biology by replacing one of the pair molecules with a two-state "electronic antigen" device comprising a hydroquinone monolayer assembled on gold, and choosing for the pair molecule an antibody that discriminates between the two electrically selected redox states of the monolayer. Application of an oxidative +0.6 V pulse to the antigen switches it to its benzoquinone state where antibodies bind the layer. A subsequent -0.6 V pulse reduces the monolayer back to the unbinding hydroquinone state, releases the specifically bound antibody molecules, and prevents further binding.     

Species Transport from Post-Flashover Fires

A study was performed to determine the use of an equivalence ratio to predict gas levels (CO, CO₂, O₂, and unburned hydrocarbons) transported to locations remote from a post-flashover compartment fire. A series of tests were conducted in a reduced-scale facility to measure the evolution of post-flashover compartment fire gases flowing down a hallway. Test variables included air entrainment into gases in the hallway, stoichiometry of the compartment fire gases entering the hallway, mass flow rate of compartment fire gases, and the presence of a vitiated smoke layer accumulated in the hallway. In cases with no layer accumulated in the hallway, species yields in the hallway were found to correlate with a control volume equivalence ratio. The control volume equivalence ratio is the ratio of the mass loss rate of fuel inside the compartment to the air flow into the compartment plus the air entrained into compartment fire gases flowing along the hallway. Layers that accumulate in the hallway were determined to limit oxidation, which in some cases resulted in CO yields transported to remote locations being 20% higher than those inside the compartment. Based on the experimental data, a methodology was developed for predicting species levels transported to remote locations.     

In defense of diligence: A rejoinder to Pelham and Carvallo (2011).

In Simonsohn (2011) I reported the results from 14 studies that suggest all existing evidence of implicit egotism in marriage, job, and location decisions is spurious. Lack of diligence by Pelham and colleagues explains in great part why the confounds behind their findings were not addressed in time. They almost never included controls, were dismissive of blatant alternative explanations, and on occasion misreported factual information that made confounds appear less important. Their rebuttal is similarly lacking in diligence. The specific empirical concerns it raised are contradicted by evidence, logic, or both. It reported misleading examples and inaccurate facts (some regarding the authors' own data). In this rejoinder I address all specific issues they raised about the empirics of my article. I then provide perhaps the most striking example of lack of diligence in their earlier work. I close on a constructive note, providing 2 concrete suggestions on how to analyze data in future implicit egotism studies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Program Verification and Functioning of Operative Computing Revisited: How about Mathematics Engineering?

The issue of proper functioning of operative computing and the utility of program verification, both in general and of specific methods, has been discussed a lot. In many of those discussions, attempts have been made to take mathematics as a model of knowledge and certitude achieving, and accordingly infer about the suitable ways to handle computing. I shortly review three approaches to the subject, and then take a stance by considering social factors which affect the epistemic status of both mathematics and computing. I use the analogy between mathematics and computing in reverse—that is to say, I consider operative computing as a form of making mathematics, and so attempt to learn from computing to mathematics in general. I conclude that “mathematics engineering” is a field to be both developed for practical improvement of doing mathematics and taken into consideration while philosophizing about mathematics as well.     

Analyzing Morphology and Thermal History of Polybutylene Terephthalate by THz Time-domain Spectroscopy

We have measured the frequency-dependent dielectric function of semi-crystalline polybutylene terephthalate (PBT) in the terahertz region between 100 GHz and approximately 2.8 THz. A characteristic band is observed around 2.38 THz. The intensity of this band is a good indicator of the degree of crystallinity of the different samples. A potential assignment of this band is proposed, based on the comparison with spectroscopic data of the structurally very similar polyethylene terephtalate (PET). Furthermore, the frequency-dependent index of refraction of PBT reveals more insight about the morphology and different thermal history of the samples under investigation.     

Measurement of wavelengths with phosphor storage image plates on a grazing incidence spectrograph

We recorded the spectra emitted by a Ne/Mg Penning discharge and by sliding spark discharges of Y and Mo in the 150-450 A range with phosphor storage image plates on a 10.7 m grazing incidence spectrograph. To obtain better conformance of the image plates to the focal surface of the concave grating, the plates were mounted on the curved surface with a backing of flexible steel plates. The exposed plates were read by a rotary drum scanner. With these techniques we achieved a wavelength accuracy of approximately 0.003 A. This is comparable to what is normally obtained with photographic plates on this instrument.