نتایج جستجو برای: pumps
تعداد نتایج: 11990 فیلتر نتایج به سال:
The mechanisms by which NaCl raises blood pressure (BP) in hypertension are unresolved, but much evidence indicates that endogenous ouabain is involved. In rodents, arterial smooth muscle cell (ASMC) Na(+) pumps with an α(2)-catalytic subunit (ouabain EC(50) ≤1.0 nM) are crucial for some hypertension models, even though ≈80% of ASMC Na(+) pumps have an α(1)-subunit (ouabain EC(50) ≈ 5 μM). Huma...
OBJECTIVES Intrathecal drug delivery systems represent an important component of interventional strategies for refractory chronic pain syndromes. Continuous intrathecal administration of opioids results in higher subarachnoid drug concentrations, improved pain scores, and less frequent side effects when compared with systemic opioid administration. Substantial costs arise at the time of surgica...
Micromachined vacuum pumps are one of the key components in miniature systems for chemical and biological analysis. Miniature sensors and analyzers are normally operated at the pressure range lower than a few millitorr. We are developing a micromachined vacuum pump that is comprised of a mechanical rough pump integrated with micromachined ion-pumps. The rough pump generates a low vacuum of tens...
Now a day centrifugal pumps are vital components of industries. Certainly, one of the most important specifications of centrifugal pumps are the performance curves. In the present work, performance curves of a centrifugal pumps are obtained by Computational fluid dynamics (CFD) and as an outcome, CFD results compare by practical curves. At the first step impeller and volute are designed with tw...
The Micro pump is an essential component in a Micro Total Analysis System (μTAS). A feasible and reliable design of the micro pump is a key for the development of the μTAS. The Valve-less Rectification Micro Pump (VRMP) has many advantages, such as: non-moving parts, independent of fluids and channels properties, reliable, and easy to fabricate. Fluid diodicity is an essential parameter of the ...
Patient controlled analgesia (PCA) and Patient-controlled epidural analgesia (PCEA) pumps are methods of pain control with complex smart infusion devices and are widely used in hospitals. Smart PCA/PCEA pumps can be programmed with the dose and rate of medications within pre-set ranges. However, adverse effects have been reported associated with these pumps' use. In this paper, we describe a pr...
We show that graphene-based quantum pumps can tap into evanescent modes, which penetrate deeply into the device as a consequence of Klein tunneling. The evanescent modes dominate pumping at the Dirac point, and give rise to a universal response under weak driving for short and wide pumps, in close analogy to their role for the minimal conductivity in ballistic transport. In contrast, evanescent...
Transfer of intensity noise from pumps to signal in dual-pump fiber-optic parametric amplifiers is simulated numerically for a realistic configuration in which both pumps are amplified and filtered before they enter the fiber. The walk-off effects induced by different group velocities of pumps, signal, and idler are fully taken into account. It is found that the optical signal-to-noise ratio ca...
This paper presents a review of some of the recent developments in our understanding of the dynamics and instabilities caused by cavitation in pumps. Focus is placed on presently available data for the transfer functions for cavitating pumps and inducers, particularly on the compliance and mass flow gain factor, which are so critical for pump and system stability. The resonant frequency for cav...
In the recent decades, due to the development of the pressurized irrigation systems, the relationship between the water and energy has been extended more than ever. So, according to problems due to the water shortage, energy saving is considered as one of the most important challenges in the agriculture section. In this study, by considering the capabilities of the pumping systems, variable spe...
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