Effect of pressure on the flow behavior of polybutene

The rheology of submicron thick polymer melt is examined under high normal pressure conditions by a recently developed photobleached‐fluorescence imaging velocimetry technique. In particular, the validity and limitation of Reynold equation solution, which suggests a linear through‐thickness velocity profile, is investigated. Polybutene (PB) is sheared between two surfaces in a point contact. The results presented in this work suggest the existence of a critical pressure below which the through‐thickness velocity profile is close to linear. At higher pressures however, the profile assumes a sigmoidal shape resembling partial plug flow. The departure of the sigmoidal profile from the linear profile increases with pressure, which is indicative of a second‐order phase/glass transition. The nature of the transition is confirmed independently by examining the pressure‐dependent dynamics of PB squeeze films. The critical pressure for flow profile transition varies with molecular weight, which is consistent with the pressure‐induced glass transition of polymer melt

The magazine´s journalistic construction Caras y Caretas in the repression of the "Semana Trágica" ("Tragic Week") in 1919

La revista Caras y Caretas, como publicación semanal de actualidad, estructuró un discurso acerca de los conflictos obreros durante la época radical (1916-1930), con las cuales ofreció su postura frente a las tensiones sociales y políticas de la época. En ese sentido, se indaga la construcción periodística de la publicación ante el reclamo de los sectores obreros en los hechos de la denominada Semana Trágica de 1919. La investigación toma para el análisis los aportes teórico-metodológicos de Roger Chartier, Miguel Rodrigo Alsina, Roberto Marafioti, Héctor Borrat, entre otros. Entre las conclusiones obtenidas, se demostró la posición del semanario como actor político de cara a los conflictos obreros y en el marco de las relaciones de dominio instituidas. Construyó un discurso que presentó realidades dicotómicas o pares antagónicos entre un “ellos” y un “nosotros”, los cuales además se diferenciaban por principios de superioridad e inferioridad y de la necesidad de asimilar o proscribir a quienes no encajaban en el orden establecido. A través de diversas estrategias discursivas, la revista legitimó prácticas represivas por parte de la policía, el Ejército y del sector parapolicial Liga Patriótica Argentina.The magazine Caras y Caretas, as a current weekly, lead a speech about the workers conflicts during the radical period (1916-1930), through which it offered it position against the social and political tensions of the epoch. In that sense, the publication ́s journalistic construction is inquired due to the workers sectors claims in what is known as “Semana Trágica” (“Tragic week”) in 1919. The research takes into account the theorical-methodological approaches for the analysis, as well as Roger Chartier, Miguel Rodrigo Alsina, Roberto Marafioti, Hector Borrat, among others. It was determined that journal position as a political actor face to the worker issues and with the power relations installed. It structured a speech that showed the dichotomous facts or antagonic pairs between “them” and “us”, who were also distinguised by superiority and inferiority principles and the need of setting aside to the ones that did not fit in the status quo. Through the different discursive strategies, the magazine legitimized repressive practices of the police, the Army and the parapolicial sector Liga Patriótica Argentina (Argentine Patriotic League)

Angular response of hot-wire probes

A new equation for the convective heat loss from the sensor of a hot-wire probe is derived which accounts for both the potential and the viscous parts of the ow past the prongs. The convective heat loss from the sensor is related to the far- eld velocity by an expression containing a term representing the potential ow around the prongs, and a term representing their viscous e ect. This latter term is absent in the response equations available in the literature but is essential in representing some features of the observed response of miniature hot-wire probes. The response equation contains only four parameters but it can reproduce, with great accuracy, the behaviour of commonly used single-wire probes. The response equation simpli es the calibration the angular response of rotated slanted hot-wire probes: only standard King's law parameters and a Reynolds-dependent drag coefficient need to be determined

Small bowel obstruction caused by a fast-growing desmoid tumor.

Desmoid tumors are rare tumors which can cause intestinal obstructions. Surgical wide excision is currently the treatment of choice, with the goal of achieving free resection margins

Robotic-Assisted Surgery Improves the Quality of Total Mesorectal Excision for Rectal Cancer Compared to Laparoscopy: Results of a Case-Controlled Analysis.

BACKGROUND: The use of a robotic surgical system is claimed to allow precise traction and counter-traction, especially in a narrow pelvis. Whether this translates to improvement of the quality of the resected specimen is not yet clear. The aim of the study was to compare the quality of the TME and the short-term oncological outcome between robotic and laparoscopic rectal cancer resections. METHODS: 20 consecutive robotic TME performed in a single institution for rectal cancer (Rob group) were matched 1:2 to 40 laparoscopic resections (Lap group) for gender, body mass index (BMI), and distance from anal verge on rigid proctoscopy. The quality of TME was assessed by 2 blinded and independent pathologists and reported according to international standardized guidelines. RESULTS: Both samples were well matched for gender, BMI (median 25.9 vs. 24.2 kg/m(2), p = 0.24), and level of the tumor (4.1 vs. 4.8 cm, p = 0.20). The quality of the TME was better in the Robotic group (complete TME: 95 vs. 55 %; p = 0.0003, nearly complete TME 5 vs. 37 %; p = 0.04, incomplete TME 0 vs. 8 %, p = 0.09). A trend for lower positive circumferential margin was observed in the Robotic group (10 vs. 25 %, p = 0.1). CONCLUSIONS: These results suggest that robotic-assisted surgery improves the quality of TME for rectal cancer. Whether this translates to better oncological outcome needs to be further investigated

A statistic study on raspberry vesicles: formation and properties

This paper gives a statistic study on the formation of ABC raspberry vesicles under bulk swelling with DPD simulations. All vesicles formed through a disc wrap-up process, i.e. a disc micelle wraps up to form a vesicle. The lifetimes of the disc micelles before they become vesicles can be characterized as short and long (tfast and tslow). Vesicles formed with tfast have a high loading efficiency and a wide size distribution. Most of them have low membrane permeability. They resist structural deformation under shear due to their high bending rigidity. Vesicles formed with tslow have a narrow size distribution. They are small, and have low loading efficiency. A large portion of them have permeable membranes with low bending rigidity and structural defects. Shear could restructure these vesicles, and hence modify their permeability. Adjusting the repulsion between solvophobic polymers and solvents impacts on lifetimes of disc micelles. A reduction in such repulsion favours tslow. The knowledge obtained can be used to design raspberry vesicles of desired size, loading and cargo release properties

Phase-averaged flow statistics in compressors using a rotated hot-wire technique

A technique based on a rotated hot wire has been developed to characterise the unsteady, three-dimensional flow field between compressor blade rows. Data are acquired from a slanted hot wire rotated through a number of orientations at each measurement point. Phase-averaged velocity statistics are obtained by solving a set of sensor response equations using a weighted, non-linear regression algorithm. The accuracy and robustness of the method were verified a priori by conducting a series of tests using synthetic data. The method is demonstrated by acquiring a full set of phase-averaged flow statistics in the wake of a compressor stator blade row. The technique allows three components of phase-averaged velocity, six components of phase-averaged deterministic stress, and six components of phase-averaged Reynolds stress to be recovered using a single rotated hot-wire probe.The authors gratefully acknowledge Rolls-Royce plc and the UK TSB TUFT programme for funding this work and granting permission for its publication

Generalization of particle impact behavior in gas turbine via non-dimensional grouping

Fouling in gas turbines is caused by airborne contaminants which, under certain conditions, adhere to aerodynamic surfaces upon impact. The growth of solid deposits causes geometric modifications of the blades in terms of both mean shape and roughness level. The consequences of particle deposition range from performance deterioration to life reduction to complete loss of power. Due to the importance of the phenomenon, several methods to model particle sticking have been proposed in literature. Most models are based on the idea of a sticking probability, defined as the likelihood a particle has to stick to a surface upon impact. Other models investigate the phenomenon from a deterministic point of view by calculating the energy available before and after the impact. The nature of the materials encountered within this environment does not lend itself to a very precise characterization, consequently, it is difficult to establish the limits of validity of sticking models based on field data or even laboratory scale experiments. As a result, predicting the growth of solid deposits in gas turbines is still a task fraught with difficulty. In this work, two nondimensional parameters are defined to describe the interaction between incident particles and a substrate, with particular reference to sticking behavior in a gas turbine. In the first part of the work, historical experimental data on particle adhesion under gas turbine-like conditions are analyzed by means of relevant dimensional quantities (e.g. particle viscosity, surface tension, and kinetic energy). After a dimensional analysis, the data then are classified using non-dimensional groups and a universal threshold for the transition from erosion to deposition and from fragmentation to splashing based on particle properties and impact conditions is identified. The relation between particle kinetic energy/surface energy and the particle temperature normalized by the softening temperature represents the original non-dimensional groups able to represent a basis of a promising adhesion criterion

End-colostomy diverticulitis with parastomal phlegmon: A case report.

Acute colonic diverticulitis is a well-known surgical emergency, which occurs in about 10 percent of patients known for diverticulosis. The case of a 77-year-old woman is reported, with past history of abdominoperineal resection with end-colostomy for low rectal adenocarcinoma, and who developed an acute colonic diverticulitis in a subcutaneous portion of colostomy with parastomal phlegmon. Initial computed tomography imaging demonstrated a significant submucosal parietal edema with local fat tissues infiltration in regard of 3 diverticula. A two-step treatment was decided: first a nonoperative treatment was initiated with 2 weeks antibiotics administration, followed by, 6 weeks after, a segmental resection of the terminal portion of the colon with redo of a new colostomy by direct open approach. Patient was discharged on the second postoperative day without complications. Follow-up at 2 weeks revealed centimetric dehiscence of the stoma, which was managed conservatively until sixth postoperative week by stomatherapists. Treatment of acute diverticulitis with parastomal phlegmon in a patient with end-colostomy could primary be nonoperative. Delayed surgical treatment with segmental colonic resection was proposed to avoid recurrence and potential associated complications