Front dynamics and entrainment of finite circular gravity currents on an unbounded uniform slope

We report on the dynamics of circular finite-release Boussinesq gravity currents on a uniform slope. The study comprises a series of highly resolved direct numerical simulations for a range of slope angles between 5∘ and 20∘ . The simulations were fixed at Reynolds number Re=5000 for all slopes considered. The temporal evolution of the front is compared to available experimental data. One of the interesting aspects of this study is the detection of a converging flow towards the centre of the gravity current. This converging flow is a result of the finite volume of the release coupled with the presence of a sloping boundary, which results in a second acceleration phase in the front velocity of the current. The details of the dynamics of this second acceleration and the redistribution of material in the current leading to its development will be discussed. These finite-release currents are invariably dominated by the head where most of the mixing and ambient entrainment occurs. We propose a simple method for defining the head of the current from which we extract various properties including the front Froude number and entrainment coefficient. The Froude number is seen to increase with steeper slopes, whereas the entrainment coefficient is observed to be weakly dependent on the bottom slope

Case Report: An Undiagnosed Bladder Diverticulum Resulting in Foley Catheter Perforation During Cesarean Section

A bladder diverticulum is diagnosed when herniated bladder mucosa forms an outpouching from the bladder. Bladder diverticula are uncommon and are significantly more common in males. The following case presents a patient with an undiagnosed bladder diverticulum which was incidentally perforated during foley catheter placement for a repeat cesarean section. The diagnosis can be difficult in those who are asymptomatic and lack risk factors, such as the following patient

The role of Ru clusters in Fe carbide suppression for the reverse water gas shift reaction over electropromoted Ru/FeOx catalysts

Abstract The formation of an iron carbide phase has been shown to inhibit the efficiency of Fe-based catalysts in the initial step of adsorbing carbon dioxide (CO2). In this study, we evaluate the effect of adding Ru clusters (20% at.) to FeOx nanowires deposited on yttria-stabilized zirconia (YSZ) for the reverse water gas shift (RWGS) reaction carried out at 300–400 °C under atmospheric conditions. STEM shows that Ru-FeOx formed a bi-phase structure with Ru clusters (1.5–2 nm) supported on FeOx nanowires (5 nm) that remain as mixed oxides after the reaction. Open-circuit catalytic measurements demonstrated that addition of Ru increased the catalytic activity and stabilized high selectivity (>99%) towards CO. The synergetic effect of Ru and FeOx was further emphasized through electrochemical polarization, which led to a reversible catalytic activity increase of up to 2.4 times. The addition of Ru inhibits the formation of inactive Fe carbide by acting as the reducing component and stabilizing the FeOx active state. This results in an improved and lasting catalytic performance and makes Ru/FeOx catalysts attractive for industrial applications

A physics-based model for frost buildup under turbulent flow using direct numerical simulations

We present a new model for frost buildup under turbulent (and laminar) flow using direct numerical simulations. The physical model consists of two layers, the air and the frost. The air layer is fully resolved and consists of solving for the velocity, temperature, and vapor mass fraction fields. The frost layer thickness is resolved using conservation of mass and energy. Both phases are dynamically coupled using the immersed boundary method. Three-dimensional simulations are conducted in an open-channel configuration. A number of challenges need to be overcome to make these simulations feasible. First, to enforce far-field conditions of zero gradient and prescribed mean temperature and humidity, a source term is added to the energy and transport equations in the flow solver. Second, the mean frost thickness is subtracted after each time step to ensure a constant mean flow thickness and level of turbulence in the numerical domain. Third, a slow-time acceleration approach, which accelerates the frost buildup by a predetermined factor, is employed to bridge the gap between the fast turbulent and slow frost buildup time scales. Finally, a frost densification scheme is used to overcome the difficulties of vertically varying frost properties. The model is validated by comparing the frost thickness and frost thickness buildup rate over a period of one hour from a cooled flat plate experiment. Both quantities compare favorably with experiments

Front dynamics of elliptical gravity currents on a uniform slope

In the present investigation, we report data from direct numerical simulations of elliptical, finite release, Boussinesq gravity currents propagating down a uniform slope. The study comprises a series of simulations of elliptical gravity currents on a range of slope angles. The shape parameters are varied to study the effects of the initial cross-sectional aspect ratio (Λ0) and mean height to lock radius ratio (Γ) on the dynamics of the gravity current. It is found that the long-time development of the current spatial mass distribution is influenced by its initial shape at smaller slope angles (θ=5∘ and 10∘) whereas the long-time motion of the gravity current is relatively insensitive to its initial shape but is sensitive to the slope angle. The switching of axes are observed for all the noncircular releases studied in the present work. Multiple acceleration phases are observed for the current center of mass in the case of the current with a small or moderate initial cross-sectional aspect ratio (Λ0=0.1, 0.2, 0.5, 1, and 2) whereas one single acceleration phase exists for the current with a large initial cross-sectional aspect ratio (Λ0=5 and 10). The Froude numbers (Fr) for the currents released with the same slope angle but different initial shapes are observed to attain a similar constant value after the second acceleration phase. The mean Froude number (¯¯¯Fr) is seen to increase with increasing slope angles. The mean height to lock radius ratio is found to affect only the early development of the current with little influence on the long-time evolution

Improved guidelines of indoor airborne transmission taking into account departure from the well-mixed assumption

The well-mixed assumption has been widely used in predicting the spread of infectious diseases in indoor spaces. It is to be expected that a perfect well-mixed state will not be achieved in an indoor space at any reasonable level of ventilation. This work evaluates the well-mixed assumption by comparing the theory with results from large eddy simulations. The robustness of the well-mixed theory is established by comparing at four different levels. The comparison also points out systematic departures in pathogen concentration which can be accurately accounted for with an easily implementable correction factor to quantities such as cumulative exposure time. With the well-mixed model as the baseline, the correction factor can be used to account for additional important problem-specific details. We demonstrate that more accurately accounting for variability in pathogen concentration can help obtain improved estimates for enhanced guidelines of indoor airborne transmission. We further demonstrate that at source-sink separation distances smaller than 5 m, the well-mixed theory on average underestimates the risk of contagion, while for distances larger than about 5 m, the well-mixed theory\u27s prediction, on average, is overly restrictive

Case Report on Leiomyosarcoma of the Vulva: A Rare Pathology

Leiomyosarcoma (LMS) of the vulva is rare. However it is the most common histologic subtype of vulvar sarcoma, accounting for approximately 1% of all vulvar malignancies. [1-8] Whether genetics and epigenetics play a role in pathogenesis is unclear. [1] The tumor is slow-growing with non-specific symptoms, has high metastatic potential, and follows a bimodal age distribution. [1-8] Diagnosis and prognosis are based upon immunohistochemical expression and criteria from early literature. [1,3,5-7] The most common therapeutic approach involves radical vulvectomy with lymph node resection. The value of adjuvant chemotherapy and radiation remains unknown. [1,3,5-8] Our case describes a 46-year-old Caucasian G2P2 female with LMS of the left labia

Case Report: An Undiagnosed Bladder Diverticulum Resulting in Foley Catheter Perforation During Cesarean Section

A bladder diverticulum is diagnosed when herniated bladder mucosa forms an outpouching from the bladder. Bladder diverticula are uncommon and are significantly more common in males. The following case presents a patient with an undiagnosed bladder diverticulum which was incidentally perforated during foley catheter placement for a repeat cesarean section. The diagnosis can be difficult in those who are asymptomatic and lack risk factors, such as the following patient

Turmeric and Its Major Compound Curcumin on Health: Bioactive Effects and Safety Profiles for Food, Pharmaceutical, Biotechnological and Medicinal Applications

Curcumin, a yellow polyphenolic pigment from the Curcuma longa L. (turmeric) rhizome, has been used for centuries for culinary and food coloring purposes, and as an ingredient for various medicinal preparations, widely used in Ayurveda and Chinese medicine. In recent decades, their biological activities have been extensively studied. Thus, this review aims to offer an in-depth discussion of curcumin applications for food and biotechnological industries, and on health promotion and disease prevention, with particular emphasis on its antioxidant, anti-inflammatory, neuroprotective, anticancer, hepatoprotective, and cardioprotective effects. Bioavailability, bioefficacy and safety features, side effects, and quality parameters of curcumin are also addressed. Finally, curcumin’s multidimensional applications, food attractiveness optimization, agro-industrial procedures to offset its instability and low bioavailability, health concerns, and upcoming strategies for clinical application are also covered

Phospho-epitope binding by the BRCT domains of hPTIP controls multiple aspects of the cellular response to DNA damage

Human (h)PTIP plays important but poorly understood roles in cellular responses to DNA damage. hPTIP interacts with 53BP1 tumour suppressor but only when 53BP1 is phosphorylated by ATM after DNA damage although the mechanism(s) and significance of the interaction of these two proteins are unclear. Here, we pinpoint a single ATM-phosphorylated residue in 53BP1—Ser25—that is required for binding of 53BP1 to hPTIP. Binding of phospho-Ser25 to hPTIP in vitro and in vivo requires two closely apposed pairs of BRCT domains at the C-terminus of hPTIP and neither pair alone can bind to phospho-Ser25, even though one of these BRCT pairs in isolation can bind to other ATM-phosphorylated epitopes. Mutations in 53BP1 and in hPTIP that prevent the interaction of the two proteins, render cells hypersensitive to DNA damage and weaken ATM signalling. The C-terminal BRCT domains of hPTIP are also required for stable retention of hPTIP at sites of DNA damage but this appears to be independent of binding to 53BP1. Thus, the BRCT domains of hPTIP play important roles in the cellular response to DNA damage