Coagulation in waste water treatment

This paper emphasizes a practical approach to the coagulation of domestic waste water. A portion of the paper is a synopsis of current published literature on the subject. Laboratory studies on the coagulation of raw domestic waste waters were conducted to provide the basis of a practical procedure for the evaluation and design of a coagulation process. Studies included the development of a relationship between the B.O.D. and the soluble and solids portion of two waste tests. The jar test was used for the studies on the coagulation process. The final section of the paper outlines the chemical cost factors involved in process selection

Sequence-based analysis of the genus Ruminococcus resolves its phylogeny and reveals strong host association

It has become increasingly clear that the composition of mammalian gut microbial communities is substantially diet driven. These microbiota form intricate mutualisms with their hosts, which have profound implications on overall health. For example, many gut microbes are involved in the conversion of host-ingested dietary polysaccharides into host-usable nutrients. One group of important gut microbial symbionts are bacteria in the genus Ruminococcus. Originally isolated from the bovine rumen, ruminococci have been found in numerous mammalian hosts, including other ruminants, and non-ruminants such as horses, pigs and humans. All ruminococci require fermentable carbohydrates for growth, and their substrate preferences appear to be based on the diet of their particular host. Most ruminococci that have been studied are those capable of degrading cellulose, much less is known about non-cellulolytic non-ruminant-associated species, and even less is known about the environmental distribution of ruminococci as a whole. Here, we capitalized on the wealth of publicly available 16S rRNA gene sequences, genomes and large-scale microbiota studies to both resolve the phylogenetic placement of described species in the genus Ruminococcus, and further demonstrate that this genus has largely unexplored diversity and a staggering host distribution. We present evidence that ruminococci are predominantly associated with herbivores and omnivores, and our data supports the hypothesis that very few ruminococci are found consistently in non-host-associated environments. This study not only helps to resolve the phylogeny of this important genus, but also provides a framework for understanding its distribution in natural systems

STEM Education Trends: A Content Analysis of Three International STEM Journals

This content analysis adds to STEM Education research by highlighting trends in the subfields of STEM education and identifying at what educational levels this research has been conducted. Since their start, all published articles were analyzed from three international STEM education research journals—IJEMST, IJSE, and J-STEM. After logging the relevant information on a spreadsheet, analyzing the data, and looking at the results, the authors identified that technology and engineering education are still underrepresented in STEM education; that more than 50% of the research focused on only one of the four STEM silos; and that most research occurred in higher education settings

Stability of the boundary layer on a rotating disk for power-law fluids

The stability of the flow due to a rotating disk is considered for non-Newtonian fluids, specifically shear-thinning fluids that satisfy the power-law (Ostwald-de Waele) relationship. In this case the basic flow is not an exact solution of the Navier–Stokes equations, however, in the limit of large Reynolds number the flow inside the three-dimensional boundary layer can be determined via a similarity solution. An asymptotic analysis is presented in the limit of large Reynolds number. It is shown that the stationary spiral instabilities observed experimentally in the Newtonian case can be described for shear-thinning fluids by a linear stability analysis. Predictions for the wavenumber and wave angle of the disturbances suggest that shear-thinning fluids may have a stabilising effect on the flow

Optogenetic Modulation of Neural Circuits that Underlie Reward Seeking

The manifestation of complex neuropsychiatric disorders such as drug and alcohol addiction is thought to result from progressive maladaptive alterations in neural circuit function. Clearly, repeated drug exposure alters a distributed network of neural circuit elements. However, a more precise understanding of addiction has been hampered by an inability to control and, consequently, identify specific circuit components that underlie addictive behaviors. The development of optogenetic strategies for selectively modulating the activity of genetically defined neuronal populations has provided a means for determining the relationship between circuit function and behavior with a level of precision that has been previously unobtainable. Here, we briefly review the main optogenetic studies that have contributed to elucidate neural circuit connectivity within the ventral tegmental area and the nucleus accumbens, two brain nuclei that are essential for the manifestation of addiction-related behaviors. Additional targeted manipulation of genetically defined neural populations in these brain regions as well as afferent and efferent structures promises to delineate the cellular mechanisms and circuit components required for the transition from natural goal-directed behavior to compulsive reward-seeking despite negative consequences

Magnetic Phase Transition of the Perovskite-type Ti Oxides

Properties and mechanism of the magnetic phase transition of the perovskite-type Ti oxides, which is driven by the Ti-O-Ti bond angle distortion, are studied theoretically by using the effective spin and pseudo-spin Hamiltonian with strong Coulomb repulsion. It is shown that the A-type antiferromagnetic(AFM(A)) to ferromagnetic(FM) phase transition occurs as the Ti-O-Ti bond angle is decreased. Through this phase transition, the orbital state is hardly changed so that the spin-exchange coupling along the c-axis changes nearly continuously from positive to negative and takes approximately zero at the phase boundary. The resultant strong two-dimensionality in the spin coupling causes a rapid suppression of the critical temperature as is observed experimentally.Comment: 9 pages, 5 figure