Influence of the Pressure on the Product Distribution in the Oxidative Dehydrogenation of Propane over a Ga2O3/MoO3 Catalyst

The yields and selectivities in both the catalyzed and non-catalyzed oxidative dehydrogenation of propane were found to increase with increasing pressure. The results showed that the maximum yields of valuable ODH products could be obtained by adjusting only reactants' partial pressure, while keeping their ratio constant

Surface Associated Amoebae on the Ctenophore, Mnemiopsis sp.

Previous work by Moss et al. (2001) reported surface associated protists on the ctenophore Mnemiopsis sp. They frequently observed the ciliate Trichodina ctenophorii and a Flabellula-like amoeba attached to the comb plate surface. They noted that the ciliate and the amoeba were found on the subsagittal, subtentacular, and the auricular comb plates. The amoeba had a maximum width of about 15 μm and cells were crescent shaped. Ultrastructural evidence suggested that these protists were parasites although the exact nature of the association remained to be determined. This was the background for the present study. The present investigation documented the frequency of occurrence of gymnamoebae on ctenophores around Florida to assess the universality of this association. In addition, the study estimated the number of Flabellula-like comb plate amoebae per comb surface. The study also set out to isolate all surface associated amoebae, including the Flabellula-like amoeba ‘symbiont’, using a variety of media formulations. The goal was to provide material to facilitate the identification and characterization of this amoeba. Over the 2 year duration of the project, 140 Mnemiopsis sp. were collected from 16 locations around Florida and surface tissue was processed for attached gymnamoebae. Eleven morphotypes of amoebae were isolated from 52 of the 140 Mnemiopsis sp. The Flabellula-like gymnamoeba was present on 85% of the specimens, and the greatest concentration on Florida ctenophores was 946 amoebae mm-2 of comb plate surface. One isolated amoeba closely resembled the Flabellula-like amoeba described by Moss et al. (2001). It is interesting to note that although most ctenophores harbored the ‘symbiont’ it was only isolated into culture 2% of the time. No geographic factors appeared to favor the presence of amoebae on ctenophores. The shortest generation time (ie. fastest growth) calculated for the flabellulid amoeba was 20.9 hours at a salinity of 10 ppt and a temperature of 23°C. The amoeba grew best in seawater supplemented with malt/yeast extract to stimulate the growth of attendant prey bacteria. The results suggest that this amoeba, which was numerous on the surface, was predisposed to life on the ctenophore surface and could only be switched to laboratory conditions with difficulty. The amoeba had an unusual stage in the life cycle forming large fused, multinucleate cells in old cultures. This, together with its unique appearance (not resembling any published species) and the problems in amplifying its DNA by PCR (encountered by collaborators at Wood’s Hole Oceanographic Center) suggest that it an interesting amoeba new to science

Mass transfer characteristics in structured packing for CO2 emission reduction processes

Acid gas treating and CO2 capture from flue gas by absorption have gained wide importance over the past few decades. With the implementation of more stringent environmental regulations and the awareness of the greenhouse effect, the need for efficient removal of acid gases such as CO2 (carbon dioxide) has increased significantly. Therefore, additional effort for research in this field is inevitable. For flue gas processes the ratio of absorption solvent to gas throughput is very different compared to acid gas treating processes owing to the atmospheric pressures and the dilution effect of combustion air. Moreover, in flue gas applications pressure drop is a very important process parameter. Packing types are required that allow for low pressure drop in combination with high interfacial areas at low liquid loading per square meter. The determination of interfacial areas in gas-liquid contactors by means of the chemical method (Danckwerts, P. V. Gas-liquid reactions; McGraw-Hill: London, 1970) has been very frequently applied. Unfortunately, many of the model systems proposed in the literature are reversible and therefore this condition possibly is not met. Versteeg et al. (Versteeg, G. F.; Kuipers, J. A. M.; Beckum, F. P. H.; van Swaaij, W. P. M. Chem. Eng. Sci. 1989, 44, 2292) have demonstrated that for reversible reactions the conditions for the determination of the interfacial area by means of the chemical method are much more severe. In a study by Raynal et al. (Raynal, L.; Ballaguet, J. P.; Berrere-Tricca, C. Chem. Eng. Sci. 2004, 59, 5395), it has been shown that there is a dependency of the interfacial area on the packing height. Unfortunately, most model systems used, e.g., CO2-caustic soda (as used by Raynal et al.), are much more complex and consist of (a set of) reversible reaction(s). The natures of these systems make the conditions at which the interfacial area can be determined much more severe and put more limitations on the process conditions and experimental equipment than a priori can be expected. Therefore, an extended absorption model is required to determine the conditions at which the interfacial area can be measured without detailed knowledge of the values of the liquid-side mass transfer coefficient, k1, beforehand.

The Inefficacy of Constitutional Torture Prohibitions

The prohibition of torture is one of the most emblematic norms of the modern human rights movement, and its prevalence in national constitution has increased steeply in the past three decades. Yet little is known about whether constitutional torture proh

Function length as a tool for malware classification

The proliferation of malware is a serious threat to computer and information systems throughout the world. Antimalware companies are continually challenged to identify and counter new malware as it is released into the wild. In attempts to speed up this identification and response, many researchers have examined ways to efficiently automate classification of malware as it appears in the environment. In this paper, we present a fast, simple and scalable method of classifying Trojans based only on the lengths of their functions. Our results indicate that function length may play a significant role in classifying malware, and, combined with other features, may result in a fast, inexpensive and scalable method of malware classification.<br /

Mobile phones in Africa: how much do we really know?

Mobile phones are a crucial mode of communication and welfare enhancement in poor countries, especially those lacking an infrastructure of fixed lines. In recent years much has been written about how mobile telephony in Africa is rapidly reducing the digital divide with developed countries. Yet, when one examines the evidence it is not at all clear what is really happening. In one country, Tanzania, for example, some observers point to the fact that 97% of the population lives under the mobile footprint, while others show that ownership is very limited. These extreme values prompted us to review the situation in Africa as a whole, in an effort to discover what is really going on

Optically probing symmetry breaking in the chiral magnet Cu2OSeO3

We report on the linear optical properties of the chiral magnet Cu2OSeO3, specifically associated with the absence of inversion symmetry, the chiral crystallographic structure, and magnetic order. Through spectroscopic ellipsometry, we observe local crystal-field excitations below the charge-transfer gap. These crystal-field excitations are optically allowed due to the lack of inversion symmetry at the Cu sites. Optical polarization rotation measurements were used to study the structural chirality and magnetic order. The temperature dependence of the natural optical rotation, originating in the chiral crystal structure, provides evidence for a finite magneto-electric effect in the helimagnetic phase. We find a large magneto-optical susceptibility on the order of V(540nm)~10^4 rad/(T*m) in the helimagnetic phase and a maximum Faraday rotation of ~165deg/mm in the ferrimagnetic phase. The large value of V can be explained by considering spin cluster formation and the relative ease of domain reorientation in this metamagnetic material. The magneto-optical activity allows us to map the magnetic phase diagram, including the skyrmion lattice phase. In addition to this, we probe and discuss the nature of the various magnetic phase transitions in Cu2OSeO3.Comment: 9 pages, 10 figure