Experimental investigation of the impact of elastic turbulence on heat transfer in a serpentine channel

AbstractThe characteristics of convective heat transfer and fluid flow within a square cross-section serpentine channel are experimentally studied for two groups of polymeric viscoelastic fluids, shear-thinning and constant-viscosity Boger solutions. The elastic turbulence can be created by the non-linear interaction between elastic stresses generated within the flowing high-molecular-weight polymer solutions and the streamline curvature. In order to confirm elastic turbulence in this geometry, pressure drop across the serpentine channel was measured. The findings indicate that the measurements of non-dimensional pressure-drop increase approximately from 1.48 to 4.82 for viscoelastic solutions compared with the Newtonian fluid over a range of Weissenberg number from 4 to 211. The convective heat transfer enhances due to elastic turbulence by up to 200% for low polymer concentration (dilute) solutions and reaches up to 380% for higher polymer concentration (semi-dilute) solutions under creeping-flow conditions in comparison to that achieved by the equivalent Newtonian fluid flow at low Graetz number (up to 14.6). We propose a modified Weissenberg number which is able to approximately collapse the mean Nusselt number data for each solution group

Quantification of mesoscale variability and geometrical reconstruction of a textile

Automated image analysis of textile surfaces allowed determination and quantification of intrinsic yarn path variabilities in a 2/2 twill weave during the lay-up process. The yarn paths were described in terms of waves and it was found that the frequencies are similar in warp and weft directions and hardly affected by introduced yarn path deformations. The most significant source of fabric variability was introduced during handling before cutting. These resulting systematic deformations will need to be considered when designing or analysing a composite component. An automated method for three dimensional reconstruction of the analysed lay-up was implemented in TexGen which will allow virtual testing of components in the future

Off-axis digital flash photography: a common cause of artefact leukocoria in children.

Leukocoria, a presenting sign in several significant pediatric ocular conditions, can be artefactually produced by off-axis flash photography in healthy eyes. The authors demonstrate the conditions needed to produce this phenomenon, which is more commonly seen in children due to their larger-sized pupils, photogenicity, and frequent off-axis shots

Longitudinal study of trachomatous trichiasis in The Gambia: barriers to acceptance of surgery.

PURPOSE: Investigation of compliance with surgery for trachomatous trichiasis has become a priority of the World Health Organization. This study was conducted to investigate attitudes toward trichiasis and its treatment and to determine the rate of surgical uptake in The Gambia. METHODS: A 1-year longitudinal study was performed in 190 subjects with trichiasis. Persons with major trichiasis (involving five lashes or more) were referred for surgery, and those with minor trichiasis were advised to epilate. Outcome measures included attitudes toward trichiasis and its treatment, reported barriers to surgical uptake, acceptance rates for surgery, and factors affecting acceptance. RESULTS: Twenty-three percent (95% confidence interval [CI] 16.5%-30.6%) of subjects with major trichiasis attended for surgery during the year. Degree of ignorance about surgery, symptoms impeding work, and a multiple income source for the head of household predicted attendance. Reported lack of time predicted nonattendance. Sixty-eight percent of patients who had undergone surgery were trichiasis free at last follow-up. CONCLUSIONS: Poor attendance for surgery remains a problem in The Gambia. Barriers include ignorance and lack of time and money. Health education and surgical delivery strategies are needed to overcome these barriers. Regular audit of surgical results is necessary, with retraining where indicated

Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes

The nature and extent of past and current hybridization between cultivated potato and wild relatives in nature is of interest to crop evolutionists, taxonomists, breeders and recently to molecular biologists because of the possibilities of inverse gene flow in the deployment of genetically-modified (GM) crops. This research proves that natural hybridization occurs in areas of potato diversity in the Andes, the possibilities for survival of these new hybrids, and shows a possible way forward in case of GM potatoes should prove advantageous in such areas

Deciphering interplay between Salmonella invasion effectors

Bacterial pathogens have evolved a specialized type III secretion system (T3SS) to translocate virulence effector proteins directly into eukaryotic target cells. Salmonellae deploy effectors that trigger localized actin reorganization to force their own entry into non-phagocytic host cells. Six effectors (SipC, SipA, SopE/2, SopB, SptP) can individually manipulate actin dynamics at the plasma membrane, which acts as a ‘signaling hub’ during Salmonella invasion. The extent of crosstalk between these spatially coincident effectors remains unknown. Here we describe trans and cis binary entry effector interplay (BENEFIT) screens that systematically examine functional associations between effectors following their delivery into the host cell. The results reveal extensive ordered synergistic and antagonistic relationships and their relative potency, and illuminate an unexpectedly sophisticated signaling network evolved through longstanding pathogen–host interaction

Surface topography of hydroxyapatite affects ROS17/2.8 cells response

Hydroxyapatite (HA) has been used in orthopedic, dental, and maxillofacial surgery as a bone substitute. The aim of this investigation was to study the effect of surface topography produced by the presence of microporosity on cell response, evaluating: cell attachment, cell morphology, cell proliferation, total protein content, and alkaline phosphatase (ALP) activity. HA discs with different percentages of microporosity (< 5%, 15%, and 30%) were confected by means of the combination of uniaxial powder pressing and different sintering conditions. ROS17/2.8 cells were cultured on HA discs. For the evaluation of attachment, cells were cultured for two hours. Cell morphology was evaluated after seven days. After seven and fourteen days, cell proliferation, total protein content, and ALP activity were measured. Data were compared by means of ANOVA and Duncan’s multiple range test, when appropriate. Cell attachment (p = 0.11) and total protein content (p = 0.31) were not affected by surface topography. Proliferation after 7 and 14 days (p = 0.0007 and p = 0.003, respectively), and ALP activity (p = 0.0007) were both significantly decreased by the most irregular surface (HA30). These results suggest that initial cell events were not affected by surface topography, while surfaces with more regular topography, as those present in HA with 15% or less of microporosity, favored intermediary and final events such as cell proliferation and ALP activity