Continuous flow actuation between external reservoirs in small-scale devices driven by surface acoustic waves

We have designed and characterized a surface acoustic wave (SAW) fluid actuation platform that significantly improves the transmission of sound energy from the SAW device into the fluid in order to obtain enhanced performance. This is in distinct contrast to previous SAW microfluidic devices where the SAW substrate is simply interfaced with a microchannel without due consideration given to the direction in which the sound energy is transmitted into the fluid, thus resulting in considerable reflective and dissipative losses due to reflection and absorption at the channel walls. For the first time, we therefore demonstrate the ability for continuous fluid transfer between independent reservoirs driven by the SAW in a miniature device and report the associated pressure-flow rate relationship, in which a maximum flow rate of 100 μl min-1 and pressure of 15 Pa were obtained. The pumping efficiency is observed to increase with input power and, at peak performance, offers an order-of-magnitude improvement over that of existing SAW micropumps that have been reported to date

Frequency effects on the scale and behavior of acoustic streaming

Acoustic streaming underpins an exciting range of fluid manipulation phenomena of rapidly growing significance in microfluidics, where the streaming often assumes the form of a steady, laminar jet emanating from the device surface, driven by the attenuation of acoustic energy within the beam of sound propagating through the liquid. The frequencies used to drive such phenomena are often chosen ad hoc to accommodate fabrication and material issues. In this work, we seek a better understanding of the effects of sound frequency and power on acoustic streaming. We present and, using surface acoustic waves, experimentally verify a laminar jet model that is based on the turbulent jet model of Lighthill, which is appropriate for acoustic streaming seen at micro-to nanoscales, between 20 and 936 MHz and over a broad range of input power. Our model eliminates the critically problematic acoustic source singularity present in Lighthill's model, replacing it with a finite emission area and enabling determination of the streaming velocity close to the source. At high acoustic power P (and hence high jet Reynolds numbers Re-J associated with fast streaming), the laminar jet model predicts a one-half power dependence (U similar to P-1/2 similar to Re-J) similar to the turbulent jet model. However, the laminar model may also be applied to jets produced at low powers-and hence low jet Reynolds numbers Re-J-where a linear relationship between the beam power and streaming velocity exists: U similar to P similar to Re-J(2). The ability of the laminar jet model to predict the acoustic streaming behavior across a broad range of frequencies and power provides a useful tool in the analysis of microfluidics devices, explaining peculiar observations made by several researchers in the literature

Substrate dependent drop deformation and wetting under high frequency vibration

We explore the peculiar steady component of a sessile drop response to MHz order vibration, found to be dependent on its initial wettability. Placed on a vibrating hydrophobic substrate, the drop elongates vertically in the direction of the incident sound wave while remaining hydrophobic. In contrast, the drop is seen to spread on a slightly hydrophilic substrate. We elucidate this discrepancy by revealing the competing effects between the radiation pressure exerted at the bulk air/water interface and the acoustic streaming force on the contact line, revealing the critical role of the flow in the viscous boundary layer

Reflections on recovery, rehabilitation and reintegration of injured service members and veterans from a bio-psychosocial-spiritualperspective

Story of rehabilitation program for soldiers seriously injury in Afghanistan WarMedical interventions regarding trauma resuscitation have increased survivorship to levels not previously attained. Multiple examples from recent conflicts illustrate the potential return to high-level function of severely injured service members following medical and rehabilitative interventions. This review addresses the goals of rehabilitation, distills hard-won lessons of the last decade of military trauma and rehabilitation, and recommends the use of a bio-psychosocial-spiritual approach to care that can be applied at all tiers of the health care system. Questions on enabling participation in meaningful life activities include the following: Why do some patients do well and others do not? What elements contribute to positive outcomes? What factors relate to suboptimal results? Lessons learned revolve around the importance of considering the physical, psychosocial and spiritual aspects of a person’s well-being; empowering patients by fostering self-efficacy; and helping patients find meaning in life events and set high-level goals. A bio-psychosocial-spiritual model from the rehabilitation medicine literature — the Canadian Model of Occupational Performance and Engagement — is proposed as a guide to the provision of person-centred care and the maximization of a person’s functioning posttrauma

Use of computed radiography in the study of an historic painting.

The authors demonstrate the use of radiography in the investigation of an historic painting and describe the potential benefits of computed radiography compared with conventional screen-film radiography. The subject for the comparison was a 16 x 19-foot oil-on-canvas painting, Scipio Africanus Freeing Massiva, by Giovanni Battista Tiepolo. Radiographs of the painting were obtained by using a portable, industrial radiographic unit and both conventional screen-film and photostimulable phosphor plate cassettes. For this investigation, computed radiography had a number of advantages over screen-film radiography, largely due to its wider dynamic range and its capabilities for enhancing the digital images with image processing tools such as magnification, edge enhancement, colorization, and airbrushing. The ability to electronically combine images from the large painting into a single composite image file was extremely valuable, as this technique was much less cumbersome and resulted in much higher quality composite images than could be achieved with conventional radiography. An additional advantage of computed radiography includes the capability to easily archive and transmit these images in a digital format for subsequent review

A new mechanism of allostery in a G protein-coupled receptor dimer

SB269652 is to our knowledge the first drug-like allosteric modulator of the dopamine D2 receptor (D2R), but it contains structural features associated with orthosteric D2R antagonists. Using a functional complementation system to control the identity of individual protomers within a dimeric D2R complex, we converted the pharmacology of the interaction between SB269652 and dopamine from allosteric to competitive by impairing ligand binding to one of the protomers, indicating that the allostery requires D2R dimers. Additional experiments identified a 'bitopic' pose for SB269652 extending from the orthosteric site into a secondary pocket at the extracellular end of the transmembrane (TM) domain, involving TM2 and TM7. Engagement of this secondary pocket was a requirement for the allosteric pharmacology of SB269652. This suggests a new mechanism whereby a bitopic ligand binds in an extended pose on one G protein–coupled receptor protomer to allosterically modulate the binding of a ligand to the orthosteric site of a second protomer

Lead Extraction in the Contemporary Setting: The LExICon Study An Observational Retrospective Study of Consecutive Laser Lead Extractions

ObjectivesThis study sought to examine the safety and efficacy of laser-assisted lead extraction and the indications, outcomes, and risk factors in a large series of consecutive patients.BackgroundThe need for lead extraction has been increasing in direct relationship to the increased numbers of cardiovascular implantable electronic devices.MethodsConsecutive patients undergoing transvenous laser-assisted lead extraction at 13 centers were included.ResultsBetween January 2004 and December 2007, 1,449 consecutive patients underwent laser-assisted lead extraction of 2,405 leads (20 to 270 procedures/site). Median implantation duration was 82.1 months (0.4 to 356.8 months). Leads were completely removed 96.5% of the time, with a 97.7% clinical success rate whereby clinical goals associated with the indication for lead removal were achieved. Failure to achieve clinical success was associated with body mass index <25 kg/m2and low extraction volume centers. Procedural failure was higher in leads implanted for >10 years and when performed in low volume centers. Major adverse events in 20 patients were directly related to the procedure (1.4%) including 4 deaths (0.28%). Major adverse effects were associated with patients with a body mass index <25 kg/m2. Overall all-cause in-hospital mortality was 1.86%; 4.3% when associated with endocarditis, 7.9% when associated with endocarditis and diabetes, and 12.4% when associated with endocarditis and creatinine ≥2.0. Indicators of all-cause in-hospital mortality were pocket infections, device-related endocarditis, diabetes, and creatinine ≥2.0.ConclusionsLead extraction employing laser sheaths is highly successful with a low procedural complication rate. Total mortality is substantially increased with pocket infections or device-related endocarditis, particularly in the setting of diabetes, renal insufficiency, or body mass index <25 kg/m2. Centers with smaller case volumes tended to have a lower rate of successful extraction