A discussion about the velocity distribution commonly used as the boundary condition in surface acoustic wave numerical simulations.

Surface acoustic waves in combination with microfluidics has become an attractive research field regarding its various medical and biological applications. It is sometimes preferred to solve just the fluid domain and apply some boundary conditions to represent other components rather than performing a coupled numerical solution. To account for the piezoelectric actuation, a conventional velocity distribution built by superposing the left-going and right-going surface waves is commonly used as the boundary condition, its correctness is assessed here by comparing it to a coupled solution. It was shown that the actual leaky surface acoustic wave in coupled solution has different wavelengths in its real and imaginary parts, sometimes gets out of being sinusoidal, and has a different form compared to the superposed formula. For the phase differences other than 0 and π between the left and right electrodes, the distance between the electrodes affects the streaming and acoustic fields in the microchannel thereby leading to deviations in particle traces. Furthermore, the ratio of the horizontal to vertical components of the surface wave was extracted from the coupled solutions and compared to its previously reported values. The sensitivity analysis showed that for small particles, this ratio does not affect the streaming pattern but changes its velocity magnitude causing a time lag. For larger particles, the ratio altered the movement direction. This study suggests not replacing the piezoelectric actuation with the boundary condition to avoid inaccuracy in resulting fields that are being used in calculations of particle tracing and acoustic radiation forces.

Quantitative assessment of parallel acoustofluidic device.

The advantage of ultrasonic fields in harmless and label-free applications intrigued researchers to develop this technology. The capability of acoustofluidic technology for medical applications has not been thoroughly analyzed and visualized. Toward efficient design, in this research, flowing fluid in a microchannel excited by acoustic waves is fully investigated. To study the behavior of acoustic streaming, the main interfering parameters such as inlet velocity, working frequency, displacement amplitude, fluid buffer material, and hybrid effect in a rectangular water-filled microchannel actuated by standing surface acoustic waves are studied. Governing equations for acoustic field and laminar flow are derived employing perturbation theory. For each set of equations, appropriate boundary conditions are applied. Results demonstrate a parallel device is capable of increasing the inlet flow for rapid operations. Frequency increment raises the acoustic streaming velocity magnitude. Displacement amplitude amplification increases the acoustic streaming velocity and helps the streaming flow dominate over the incoming flow. The qualitative analysis of the hybrid effect shows using hard walls can significantly increase the streaming power without depleting excessive energy. A combination of several effective parameters provides an energy-efficient and fully controllable device for biomedical applications such as fluid mixing and cell lysis.

Carnoy's solution fixation with compression significantly increases the number of lymph nodes yielded from colorectal cancer specimens.

BACKGROUND AND OBJECTIVES: Carnoy's fixation and compression represents a novel technique to enhance lymph node evaluation and accuracy of staging after colorectal cancer resection. METHODS: This study was performed in all adults undergoing colorectal cancer operations by Kaiser Permanente surgeons at two separate facilities. Patients were assigned to either location based upon surgeon and patient availability. One group of patients had their lymph nodes examined with current standard manual technique (MT). The other group had their specimens fixed with Carnoy's solution and then compressed (CT) to assess for lymph nodes. RESULTS: A total of 157 patients were enrolled. Seventy-eight patient specimens underwent MT and 79 patient specimens underwent the new compression technique (CT). CT resulted in a significant increase in total lymph node yield per specimen (37.6 ± 18.5 nodes with CT vs 18.9 ± 8.8 nodes with MT; P < 0.0001). CT also resulted in sufficient lymph node sampling (>12 nodes) in all 79 patients in the group compared with 13 of 78 patients (17%) with an insufficient lymph node evaluation in the MT group ( P = 0.0002). CONCLUSION: This study demonstrated that Carnoy's fixation with compression can significantly increase lymph node yields in colorectal cancer specimens and allow for a higher rate of adequate lymph node sampling.

Five Simultaneous Primary Tumors in a Single Patient: A Case Report and Review of the Literature.

Multiple primary malignancies (MPMs) are present when a patient is diagnosed with more than one primary malignancy and when each tumor is histologically unrelated to the others. MPMs are considered synchronous when they present within 6 months of one another. Here, we report the case of a 57-year-old woman with a past medical history significant for melanoma in 1988, who presented in 2014 with 5 distinct tumors within 4 months: malignant melanoma of the right popliteal fossa, invasive lobular breast carcinoma, diffuse large B cell lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, and a giant cell tumor of tendon sheath/pigmented villonodular synovitis. We discuss her treatment and also present a brief review of the literature. The incidence of MPMs appears to be on the rise, which demands an interdisciplinary, multimodal, and personalized approach to care.