CFD Port Flow Simulation of Air Flow Rate in Spark Ignition Engine

In the early stages of development of internal combustion engine (ICE), limitations such as speed, range, and lifespan led to series of researches resulting in the reduction or elimination of these limitations. Combustion in ICE is a rapid and controlled endothermic reaction between air in oxygen and fuel which is accompanied by significant increase in temperature and pressure with the production of heat, flame and carbon particle deposits. This combustion process is a phenomenon that involves turbulence, loss of air-fuel mixture during inflow and outflow into the cylinder. The objection of this study is to perform port flow analysis on ICE to determine flow rate and swirl at different valve lift under stationary engine parts.Methodology employed to analyze and solve the ICE port flow simulation is the use of CFD software that uses the finite volume method of numerical analysis to solve the continuity, Navier-Stokes and energy equations governing the air medium in the internal combustion engine cylinder. The model geometry for the analysis was generated using the Ansys Design Modeller for one cylinder, one suction port and one exhaust port, and two valves. The domain considered is internal combustion engine suction port with 86741 nodes and 263155 elements. Study results revealed that air mass was more concentrated around the valve and inlet port cross-section with swirling motion seen, air stream experienced turbulence as it flowed downwards inside the cylinder, air stream spread was turbulent which will eventually enhance smooth combustion, swirling air stream moves towards the cylinder wall where it experienced tumbling and turbulent which will eventually enhance smooth combustion. From the simulation it was revealed that mass flow rate of inlet air increases with valve lift

Preoperative surgical risk stratification in osteosarcoma based on the proximity to the major vessels

Aims The aim of this study was to determine the risk of local recurrence and survival in patients with osteosarcoma based on the proximity of the tumour to the major vessels. Patients and Methods A total of 226 patients with high-grade non-metastatic osteosarcoma in the limbs were investigated. Median age at diagnosis was 15 years (4 to 67) with the ratio of male to female patients being 1.5:1. The most common site of the tumour was the femur (n = 103) followed by tibia (n = 66). The vascular proximity was categorized based on the preoperative MRI after neoadjuvant chemotherapy into four types: type 1 > 5 mm; type 2 ≤ 5 mm, > 0 mm; type 3 attached; type 4 surrounded. Results Limb salvage rate based on the proximity type was 92%, 88%, 51%, and 0% for types 1 to 4, respectively, and the overall survival at five years was 82%, 77%, 57%, and 67%, respectively (p Conclusion The proximity of osteosarcoma to major blood vessels is a poor prognostic factor for local control and survival. Amputation offers better local control for tumours attached to the blood vessels but does not improve survival. Limb salvage surgery offers similar local control if the tumour attachment to blood vessels is limited

A giant ectopic hidradenoma papilliferum in a Niger delta region of Nigeria

Hidradenoma papilliferum is a known example of adnexal skin tumours with apocrine differentiation. It is a rare benign tumour which tends to arise from areas with rich concentration of aporine glands such as anogenital region, vulval, perineal, axillae, and periumbilical areas. In this report, the tumour was found in the upper outer quadrant of left breast, being one of the ectopic sites for this tumour. Contrary to most reports where male preponderance was popular for ectopic hidradenoma papilliferum, the patient in this report is a 71-year-old female. Considering the location of this tumour in this report, the likely histopathological differential diagnoses such as tubular apocrine adenoma, clear cell (apocrine) adenoma, lipoma, intraductal papilloma and papillary carcinoma of the breast should be considered for exclusion. This is the first reported case of a giant ectopic hidradenoma papilliferum of the breast in a Niger Delta region of Nigeria which also highlights the role of fine needle aspiration and cytology in the diagnosis of breast lesions

Mammalian Atg8 proteins regulate lysosome and autolysosome biogenesis through SNAREs

Mammalian homologs of the yeast Atg8 protein (mAtg8s) are important in autophagy, but their exact mode of action remains to be defined. Recently, syntaxin 17 (Stx17), a SNARE with major roles in autophagy, was shown to bind mAtg8s. Here we broadened the analysis of potential mAtg8-SNARE interactions and identified LC3-interacting regions (LIRs) in several SNAREs. Syntaxin 16 (Stx16), and its cognate SNARE partners all have LIR motifs and bind mAtg8s. A knockout in STX16 caused defects in lysosome biogenesis whereas a double STX16 and STX17 knockout completely blocked autophagic flux and decreased mitophagy, pexophagy, xenophagy, and ribophagy. Mechanistic analyses revealed that mAtg8s and Stx16 maintained several aspects of lysosomal compartments including their functionality as platforms for active mTOR. These findings reveal a broad direct interaction of mAtg8s with SNAREs with impact on membrane remodeling in eukaryotic cells and expand the roles of mAtg8s to lysosome biogenesis.</p

Understanding mechanisms of asphaltene adsorption from organic solvent on mica

The adsorption process of asphaltene onto molecularly smooth mica surfaces from toluene solutions of various concentrations (0.01-1 wt %) was studied using a surface forces apparatus (SFA). Adsorption of asphaltenes onto mica was found to be highly dependent on adsorption time and asphaltene concentration of the solution. The adsorption of asphaltenes led to an attractive bridging force between the mica surfaces in asphaltene solution. The adsorption process was identified as being controlled by the diffusion of asphaltenes from the bulk solution to the mica surface with a diffusion coefficient on the order of 10-10 m2/s at room temperature, depending on the asphaltene bulk concentration. This diffusion coefficient corresponds to a hydrodynamic molecular radius of approximately 0.5 nm, indicating that asphaltene diffuses to mica surfaces as individual molecules at very low concentration (e.g., 0.01 wt %). Atomic force microscopy images of the adsorbed asphaltenes on mica support the results of the SFA force measurements. The results from the SFA force measurements provide valuable insights into the molecular interactions (e.g., steric repulsion and bridging attraction as a function of distance) of asphaltenes in organic media and hence their roles in crude oil and bitumen production

Two Genetic Determinants Acquired Late in Mus Evolution Regulate the Inclusion of Exon 5, which Alters Mouse APOBEC3 Translation Efficiency

Mouse apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like editing complex 3 (mA3), an intracellular antiviral factor, has 2 allelic variations that are linked with different susceptibilities to beta- and gammaretrovirus infections among various mouse strains. In virus-resistant C57BL/6 (B6) mice, mA3 transcripts are more abundant than those in susceptible BALB/c mice both in the spleen and bone marrow. These strains of mice also express mA3 transcripts with different splicing patterns: B6 mice preferentially express exon 5-deficient (Δ5) mA3 mRNA, while BALB/c mice produce exon 5-containing full-length mA3 mRNA as the major transcript. Although the protein product of the Δ5 mRNA exerts stronger antiretroviral activities than the full-length protein, how exon 5 affects mA3 antiviral activity, as well as the genetic mechanisms regulating exon 5 inclusion into the mA3 transcripts, remains largely uncharacterized. Here we show that mA3 exon 5 is indeed a functional element that influences protein synthesis at a post-transcriptional level. We further employed in vitro splicing assays using genomic DNA clones to identify two critical polymorphisms affecting the inclusion of exon 5 into mA3 transcripts: the number of TCCT repeats upstream of exon 5 and the single nucleotide polymorphism within exon 5 located 12 bases upstream of the exon 5/intron 5 boundary. Distribution of the above polymorphisms among different Mus species indicates that the inclusion of exon 5 into mA3 mRNA is a relatively recent event in the evolution of mice. The widespread geographic distribution of this exon 5-including genetic variant suggests that in some Mus populations the cost of maintaining an effective but mutagenic enzyme may outweigh its antiviral function

The Restriction of Zoonotic PERV Transmission by Human APOBEC3G

The human APOBEC3G protein is an innate anti-viral factor that can dominantly inhibit the replication of some endogenous and exogenous retroviruses. The prospects of purposefully harnessing such an anti-viral defense are under investigation. Here, long-term co-culture experiments were used to show that porcine endogenous retrovirus (PERV) transmission from pig to human cells is reduced to nearly undetectable levels by expressing human APOBEC3G in virus-producing pig kidney cells. Inhibition occurred by a deamination-independent mechanism, likely after particle production but before the virus could immortalize by integration into human genomic DNA. PERV inhibition did not require the DNA cytosine deaminase activity of APOBEC3G and, correspondingly, APOBEC3G-attributable hypermutations were not detected. In contrast, over-expression of the sole endogenous APOBEC3 protein of pigs failed to interfere significantly with PERV transmission. Together, these data constitute the first proof-of-principle demonstration that APOBEC3 proteins can be used to fortify the innate anti-viral defenses of cells to prevent the zoonotic transmission of an endogenous retrovirus. These studies suggest that human APOBEC3G-transgenic pigs will provide safer, PERV-less xenotransplantation resources and that analogous cross-species APOBEC3-dependent restriction strategies may be useful for thwarting other endogenous as well as exogenous retrovirus infections