Peristaltic Pumping of Blood Through Small Vessels of Varying Cross-section

The paper is devoted to a study of the peristaltic motion of blood in the micro-circulatory system. The vessel is considered to be of varying cross-section. The progressive peristaltic waves are taken to be of sinusoidal nature. Blood is considered to be a Herschel-Bulkley fluid. Of particular concern here is to investigate the effects of amplitude ratio, mean pressure gradient, yield stress and the power law index on the velocity distribution, streamline pattern and wall shear stress. On the basis of the derived analytical expression, extensive numerical calculations have been made. The study reveals that velocity of blood and wall shear stress are appreciably affected due to the non-uniform geometry of blood vessels. They are also highly sensitive to the magnitude of the amplitude ratio and the value of the fluid index.Comment: Accepted for publication in ASME journal of Applied Mechanics. arXiv admin note: text overlap with arXiv:1108.1285v

Measurements of D0-D0bar Mixing and Searches for CP Violation: HFAG Combination of all Data

We present world average values for D0-D0bar mixing parameters x and y, CP violation parameters |q/p| and Arg(q/p), and strong phase differences \delta and \delta_{K\pi\pi}. These values are calculated by the Heavy Flavor Averaging Group (HFAG) by performing a global fit to relevant experimental measurements. The results for x and y differ significantly from zero and are inconsistent with no mixing at the level of 6.7 sigma. The results for |q/p| and Arg(q/p) are consistent with no CP violation. The strong phase difference \delta is less than 45 degrees at 95% C.L.Comment: 8 pages, 5 figures, 4 tables, presented at the BES-Belle-CLEO-Babar Joint Workshop on Charm Physics, November 26-27, 2007 in Beijing China. To appear in Chinese Physics C (HEP & NP). v2: typo correcte

Granular Assembly of α-Synuclein Leading to the Accelerated Amyloid Fibril Formation with Shear Stress

α-Synuclein participates in the Lewy body formation of Parkinson's disease. Elucidation of the underlying molecular mechanism of the amyloid fibril formation is crucial not only to develop a controlling strategy toward the disease, but also to apply the protein fibrils for future biotechnology. Discernable homogeneous granules of α-synuclein composed of approximately 11 monomers in average were isolated in the middle of a lag phase during the in vitro fibrillation process. They were demonstrated to experience almost instantaneous fibrillation during a single 12-min centrifugal membrane-filtration at 14,000×g. The granular assembly leading to the drastically accelerated fibril formation was demonstrated to be a result of the physical influence of shear force imposed on the preformed granular structures by either centrifugal filtration or rheometer. Structural rearrangement of the preformed oligomomeric structures is attributable for the suprastructure formation in which the granules act as a growing unit for the fibril formation. To parallel the prevailing notion of nucleation-dependent amyloidosis, we propose a double-concerted fibrillation model as one of the mechanisms to explain the in vitro fibrillation of α-synuclein, in which two consecutive concerted associations of monomers and subsequent oligomeric granular species are responsible for the eventual amyloid fibril formation

Slip and hall current effects on Jeffrey fluid suspension flow in a peristaltic hydromagnetic blood micropump

The magnetic properties of blood allow it to be manipulated with an electromagnetic field. Electromagnetic blood flow pumps are a robust technology which provide more elegant and sustainable performance compared with conventional medical pumps. Blood is a complex multi-phase suspension with non-Newtonian characteristics which are significant in micro-scale transport. Motivated by such applications, in the present article a mathematical model is developed for magnetohydrodynamic (MHD) pumping of blood in a deformable channel with peristaltic waves. A Jeffery’s viscoelastic formulation is employed for the rheology of blood. A twophase fluid-particle (“dusty”) model is utilized to better simulate suspension characteristics (plasma and erythrocytes). Hall current and wall slip effects are incorporated to achieve more realistic representation of actual systems. A two-dimensional asymmetric channel with dissimilar peristaltic wave trains propagating along the walls is considered. The governing conservation equations for mass, fluid and particle momentum are formulated with appropriate boundary conditions. The model is simplified using of long wavelength and creeping flow approximations. The model is also transformed from the fixed frame to the wave frame and rendered non-dimensional. Analytical solutions are derived. The resulting boundary value problem is solved analytically and exact expressions are derived for the fluid velocity, particulate velocity, fluid/particle fluid and particulate volumetric flow rates, axial pressure gradient, pressure rise and skin friction distributions are evaluated in detail. Increasing Hall current parameter reduces bolus growth in the channel, particle phase velocity and pressure difference in the augmented pumping region whereas it increases fluid phase velocity, axial pressure gradient and pressure difference in the pumping region. Increasing the hydrodynamic slip parameter accelerates both particulate and fluid phase flow at and close to the channel walls, enhances wall skin friction, boosts pressure difference in the augmented pumping region and increases bolus magnitudes. Increasing viscoelastic parameter (stress relaxation time to retardation time ratio) decelerates the fluid phase flow, accelerates the particle phase flow, decreases axial pressure gradient, elevates pressure difference in the augmented pumping region and reduces pressure difference in the pumping region. Increasing drag particulate suspension parameter decelerates the particle phase velocity, accelerates the fluid phase velocity, strongly elevates axial pressure gradient and reduces pressure difference (across one wavelength) in the augmented pumping region. Increasing particulate volume fraction density enhances bolus magnitudes in both the upper and lower zones of the channel and elevates pressure rise in the augmented pumping region

A next generation, pilot-scale continuous sterilization system for fermentation media

A new continuous sterilization system was designed, constructed, started up, and qualified for media sterilization for secondary metabolite cultivations, bioconversions, and enzyme production. An existing Honeywell Total Distributed Control 3000-based control system was extended using redundant High performance Process Manager controllers for 98 I/O (input/output) points. This new equipment was retrofitted into an industrial research fermentation pilot plant, designed and constructed in the early 1980s. Design strategies of this new continuous sterilizer system and the expanded control system are described and compared with the literature (including dairy and bio-waste inactivation applications) and the weaknesses of the prior installation for expected effectiveness. In addition, the reasoning behind selection of some of these improved features has been incorporated. Examples of enhancements adopted include sanitary heat exchanger (HEX) design, incorporation of a “flash” cooling HEX, on-line calculation of F(o) and R(o), and use of field I/O modules located near the vessel to permit low-cost addition of new instrumentation. Sterilizer performance also was characterized over the expected range of operating conditions. Differences between design and observed temperature, pressure, and other profiles were quantified and investigated

Orthokeratology: clinical utility and patient perspectives

Jessie Charm Sight Enhancement Center, Hong Kong Special Administrative Region Abstract: Orthokeratology (ortho-k) is a special rigid contact lens worn at night to achieve myopic reduction and control. This review provides an overview on prescribing ortho-k, including clinical consideration on patient aspect and lens design; its clinical outcomes; and clinical efficacy and safety. Patient satisfaction was summarized. In order to achieve long-term healthy ortho-k treatment, it requires both patient and practitioners’ care and rapport to maintain good ocular health and lens conditions. Keywords: orthokeratology, efficacy, patient satisfaction, myopic reduction, myopic contro

Do Protein Molecules Unfold in a Simple Shear Flow?

Protein molecules typically unfold (denature) when subjected to extremes of heat, cold, pH, solvent composition, or mechanical stress. One might expect that shearing forces induced by a nonuniform fluid flow would also destabilize proteins, as when a protein solution flows rapidly through a narrow channel. However, although the protein literature contains many references to shear denaturation, we find little quantitative evidence for the phenomenon. We have investigated whether a high shear can destabilize a small globular protein to any measurable extent. We study a protein (horse cytochrome c, 104 amino acids) whose fluorescence increases sharply upon unfolding. By forcing the sample through a silica capillary (inner diameter 150–180 μm) at speeds approaching 10 m/s, we subject the protein to shear rates dv(z)/dr as large as ∼2 × 10(5) s(−1) while illuminating it with an ultraviolet laser. We can readily detect fluorescence changes of <1%, corresponding to shifts of <∼0.01 kJ/mol in the stability of the folded state. We find no evidence that even our highest shear rates significantly destabilize the folded protein. A simple model suggests that extraordinary shear rates, ∼10(7) s(−1), would be required to denature typical small, globular proteins in water

Ergonomic Design of Public Bus in The Philippines with Provision for Senior Citizens and Persons with Disability

Comfortability in buses for commuters particularly those with special needs such as senior citizen and person with disability is a concern, which requires attention. Public buses are highly used mode of transportation in the Philippines, both provincial and city. In this work, the researchers aim to determine the design factors that affect the comfortability of commuters and eventually come up with an ergonomic design of public bus to be used in the Philippines with provision for senior citizen and persons with disability. The study covers and mainly focused on designing bus doors and its interior for the accessibility of the senior citizens and persons with mobility aid such as wheelchairs, crutches and canes ergonomically. The researchers have conducted review of related literature, direct observation, surveys, interviews and actual measurements of bus dimensions in order to describe factually and accurately the current design of buses in the Philippines. The researchers have improved the current design of provincial public buses having trips from Cavite to Manila (vice versa) with consideration of the issues and needs of the commuters in riding a bus