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Powerful synergies between phosphonate, zinc oxide, and acrylamido-tert-butyl-sulfonate (ATBS) copolymer chemical additives render superior performance in a high-temperature retarder system for oil well grade Portland cement. The phosphonate retarder and ATBS-based retarders establish a two-tiered strength development where amorphous C-S-H converts to crystalline dicalcium silicate hydrate (C2SH) in the first (low compressive strength) tier prior to the reaction of Portlandite with quartz. The three additive retarder system can be tuned with nanosilica to eliminate the two-tiered strength development effect leading to a smooth transition from the cement in the slurry form directly to its highest compressive strength.
Acoustic streaming generated by a plane standing wave between two infinite plates or inside a cylindrical tube is considered, under the isentropic flow assumption. A two-dimensional analysis is performed in the linear case of slow streaming motion, based on analytical formal solutions of separate problems, each associated with a specific source term (Reynolds stress term). In order to obtain these analytical solutions, a necessary geometrical hypothesis is that
are the guide half-width (or radius) and length. The effect of the two source terms classically taken into account is quantified in order to derive the dependence of the maximum axial streaming velocity on the axis as a function of the ratio
is the acoustic boundary layer thickness. The effect of two other source terms that are usually neglected, is then analysed. It is found that one of these terms can generate a counter-rotating streaming flow. While negligible for very narrow guides, this term can become important for some values of the aspect ratio
Despite being classed as an asocial species, aggregations of sea anemones can be common in abundant species. UK populations of the geographically common aggressive intertidal sea anemone Actinia equina, form clustered aggregations notwithstanding a violent nature towards neighbours and relatives. Smaller in body size, and more abundant than those found in warmer climates, little research has been undertaken to discover what factors affect body size. This study investigates whether aggregation, distance to neighbour, submergence at low tide or pH in rock pools affect body size of A. equina in their natural habitat. Populations were investigated at five sites on the Yorkshire coast during August and September 2016. A total of 562 anemones were recorded revealing that solitary anemones were significantly larger than those found in clustered aggregations. In addition, anemones found submerged in rock pools at low tide were significantly larger than those found on emergent rock, and smaller anemones were found in significantly higher pH conditions (8.5+) than larger anemones. Anemones submerged at low tide are constantly able to feed and not subject to harsh conditions such as wind exposure and temperature, hence they can achieve larger sizes. Consequently, the size of the anemones may reflect a trade-off between the benefits of aggregating in exposed environments and the costs of competition for a reduced food resource.
In the current manuscript we discuss the response of dynamic metallogels that display reversion to the liquid state when exposed to phosphines. The metallogels are formed through the condensation of formaldehyde and poly(alkyloxide)amines in polar aprotic solvents. The gel formation can be catalyzed with trivalent metals (Al(III and Fe(III)) with concomitant enhanced dynamism (gelation/degelation). When various phosphines are introduced, the metallogel is irreversibly liquefied. This process adds a new vector for controlling the bulk properties of this class of materials. Here, we explore the mechanism in detail for the reaction of tris(carboxyethyl)phosphine with N,N,N-triethoxylethyl-1,3,5-hexahydro-1,3,5-triazine (HEHT, 1) a stable derivative of the active hexahydrotriazine (HT) core in dimethylformamide in the presence or absence of Al(III). Additionally, density functional theory is used on the model N,N,N-trimethyl system (MHT, 2) to estimate reaction parameters and predict nuclear magnetic resonance spectra.
By 2050, the number of people aged sixty years and older with schizophrenia is expected to double and affect about 10 million people worldwide. Psychoses are among the most common experiences in later life, with a lifetime risk of 23 percent. As a result, there is a looming crisis in mental health care. Schizophrenia and Psychoses in Later Life is the first major multidisciplinary reference on these important disorders. The book provides guidelines for clinical care, research and policy that are consistent with the emerging paradigmatic changes occurring with respect to schizophrenia in later life. This book features multidisciplinary contributions from experts in the fields of biological psychiatry, social psychiatry, sociology, anthropology, social work, psychology, and neuropsychology that will help professionals to integrate services and attain the best outcomes. The text will guide psychiatrists, psychologists, gerontologists, policymakers, and social scientists in creating innovative new programs to help this underserved and growing population.
This essay examines the theory of individual agency that propels the central thesis in Kenneth Mack's Representing the Race: The Creation of the Civil Rights Lawyer (2012)—namely, that an important yet understudied means by which African American civil rights lawyers changed conceptions of race through their work was through their very performance of the professional role of lawyer. Mack shows that this performance was inevitably fraught with tension and contradiction because African American lawyers were called upon to act both as exemplary representatives of their race and as performers of a professional role that traditionally had been reserved for whites only. Mack focuses especially on the tensions of this role in courtrooms, where African American lawyers were necessarily called upon to act as the equals of white judges, opposing counsel, and witnesses. Mack's thesis, focused on the contradictions and tensions embodied in the performance of a racially loaded identity, reflects the influence of postmodern identity performance theory as articulated by Judith Butler and others. Mack and others belong to a new generation of civil rights history scholars who are asking new questions about contested identities related to race, gender, sexuality, and class. This essay offers an evaluation of this new direction for civil rights scholarship, focusing especially on its implicit normative orientation and what it contributes to the decade‐old debate over how to conceive of agency in social movement scholarship.