l. chen

The microchannel heat sink is a commonly used structure in mechanical cooling systems for microelectronics. Based on bionics, a simplified heat sink with a spider-web design is proposed in this paper. Under the condition of bottom heat flux q = 100 W/cm2 and Reynolds number (Re) = 442–884, the influence of three parameters (main channel width, branch width and rib width) on the performance of a spider web microchannel heat sink (SW-MCHS) under different Re conditions was numerically analyzed by computational fluid dynamics. The results showed that the main channel had the greatest influence on the Nusselt number (Nu) and the Euler number (Eu); With the increase of main channel width, Nu increased by 46.97%, and Eu decreased by 31.74%. Rib width had the smallest influence on Nu and Eu; With the increase of rib width, Nu decreased by 7.18%, and Eu decreased by 12.00%. Based on the research results, the correlations for predicting Nu and Eu of the SW-MCHS were fitted; the  values for the two correlations were 0.9523 and 0.9246, respectively. These fitting correlations could be used to predict Nu and Eu for the SW-MCHS. The present study has contributed to advancing the applications of microchannel heat sinks and enhancing the cooling efficiency of mechanical microelectronics cooling systems.

To investigate the effects of laparoscopic ultrasound (LUS)-guided microwave ablation (MWA) combined with surgical resection on liver function and immune function of primary liver cancer (PLC) patients.

Clinical data of 100 patients with PLC after surgery in our hospital from January 2021 to December 2023 were retrospectively analyzed, and divided into laparoscopic hepatectomy (LH group) and laparoscopic ultrasound-guided microwave ablation combined with laparoscopic hepatectomy (LMWA+LH group). Clinical indicators, clinical efficacy, liver function, tumor markers, immune function, incidence of complications, postoperative overall survival rate along with tumor free survival rate between groups were compared.

Compared with the LH group, the intraoperative blood loss and postoperative hospital stay was decreased in the LMWA+LH group (P<0.05). Total effective rate of the LMWA+LH group was 90.00%, higher than the 70.00% in LH group (P<0.05). After therapy, reduction in aspartate alanine aminotransferase (ALT), aminotransferase (AST), total bilirubin (TBIL), and the elevation in albumin (ALB) in the LMWA+LH group were more obvious (P<0.05). The LMWA+LH group showed more obvious elevation in CD4+ and CD4+/CD8+ levels and reduction in CD8+ level relative to the LH group (P<0.05). The complication incidence showed no statistical difference between groups (P>0.05). Postoperative survival and tumor free survival rates in the LMWA+LH group were higher than LH group (P<0.05).

Laparoscopic ultrasound-guided microwave ablation combined with surgical resection promotes the postoperative recovery, improves liver function and immune function and improves patient survival rate, which might provide guidance for clinical practice.

A retrospective cohort study was conducted to analyze the diagnostic value and image features of chest computed tomography (CT) scan in children with lobar pneumonia (LP) before and after treatment.

172 children with lobar pneumonia treated from January 2016 to December 2021 were selected. The patients who underwent plain X-ray scan were divided into control group (n = 72) and the patients who underwent chest CT scan as study group (n = 100). The diagnostic value and image characteristics before and after treatment were compared between the two groups.

After treatment, the lesion area of the patient was absorbed in varying degrees, and the CT plain scan indicated that the solid shadow density decreased until it was completely absorbed. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of chest X-ray were 66.67%, 58.33%, 63.89%, 76.19% and 46.67% respectively; and chest CT scan were 82.98%, 67.92%, 75.00%, 69.64% and 81.82%. The sensitivity, specificity, accuracy, and negative predictive value of chest CT plain scan were higher, and the positive predictive value was lower compared to those of chest X-ray plain film. The results of ROC curve study indicated that the AUC of chest CT plain scan was 0.755 (95%CI=0.657-0.852), and the AUC of chest X-ray film was 0.625 (95%CI= 0.489-0.744).

Chest CT has high sensitivity and specificity in the diagnosis of LP in children, which can clearly demonstrate the imaging features of LP before and after treatment.

A numerical simulation is used to investigate the flow field characteristics of a three-dimensional over-under turbine-based combined cycle circular-to-rectangular transition exhaust nozzle when only the turbojet flowpath is in operation. The effect on the exhaust nozzle performance of there being a secondary injection on the ramp of the expansion section of the turbojet flow path is then examined. Finally, the impact of variations in the secondary injection design parameters is further investigated. The results show that a secondary injection can improve the exhaust nozzle's performance by reducing the axial force on the inner wall of the flow path. However, changes in flight status can undermine this improvement. Under the baseline operating condition, a secondary injection with a larger angle and close to the ramp outlet can produce a more significant improvement in nozzle performance. In this study, the axial thrust coefficient, lift and pitch moment of the nozzle can be improved by a maximum of 9.312%, 66.007% and 10.975%, respectively.

NatuAt present, radioactive seed implantation is a common treatment for prostate cancer, the TPS (treatment planning system) calculates the dose by adding the dose attributed to each source. However, the interseed attenuation effect would result in a difference between the actual dose and the calculated dose. The aim of this study was to identify the factors influencing the interseed attenuation effect.

I-125 seed sources were selected, and MC (Monte Carlo) method was used to simulate the dose distribution around seed sources. The results obtained from the linear addition of a single-source dose were compared with those obtained considering the interseed attenuation effect. The effects of the medium, source arrangement and source number on the dose were evaluated.

The MC simulation results for multiple seed sources are lower than those for linear additive doses in most areas. In different medium, the mean error caused by interseed attenuation effect is the smallest in adipose tissue (0.52%) and the largest in bone (1.41%). Taking four sources as examples, the maximum error is 9.34%, appearing in the plane where the source is located. The error decreases to 1.3% when the source is located 2 mm away from the source plane. The more scattered the sources are in space, the smaller the error will be.

A high atomic number and high-density medium will cause a high error. The area with a high error is mainly observed in the plane where the sources are located, the edge error of the source distribution area is larger.

The cylindrical volute intake structure possesses some advantages including convenient processing, convenient installation & uninstallation and high machining efficiency. The helium turboexpander with this novel intake structure in a superconducting cryogenic device is investigated deeply in this study. Based on the established mathematical model and the corresponding numerical computation methods, the whole flow passage internal flow of the helium turboexpander is numerically simulated. And then the distribution characteristics of total pressure, static pressure, static temperature, relative velocity and total enthalpy in the cylindrical volute, nozzle, impeller and diffuser are explored, and loss mechanism of the internal flow is analyzed. The results indicate that the novel cylindrical volute intake structure has obvious pre-rotation effect on the inlet flow field of the nozzle, and this intake structure has little loss. In addition, the expansion effect in downstream components including nozzle and impeller is obvious, and the flow field changes uniformly. The overall efficiency of the turboexpander is up to 84.8%, which indicates that it is reasonable that the novel cylindrical volute is used as the intake structure of turboexpander.

In head and neck radiotherapy, immobilization devices can affect dose delivery. In this study, a comprehensive end-to-end test was developed to evaluate the accuracy of radiotherapy treatment.

An Alderson Radiation Therapy (ART) anthropomorphic phantom with EBT3 film was used to mimic the actual patient treatment process. Ten patients treated for nasopharyngeal carcinomas with IMRT were retrospectively selected. For each patient, the treatment plan, as well as the targets and OARs was transplanted onto the phantom, and the IMRT plan was subsequently recalculated to the phantom with EBT3 film. Two quality assurance (QA) plans were generated, namely “Plan-with” wherein the immobilization device was contoured and “Plan-without” wherein it was omitted. EBT3 measurements were compared with the results of the TPS calculation.

With different gamma calculation criteria applied, the results obtained for Plan-with were closer to the dose measured with the EBT3 film. Moreover, 1.8% deviation was observed in the posterior neck skin dose for Plan-with when compared to the film measurements while the value was 33.1% lower for Plan-without. When compared to Plan-without, each target volume in Plan-with exhibited a 1–4% reduction in the maximum dose (D2%), minimum dose (D98%) and mean dose (Dmean).

Immobilization devices decrease the radiation dose to target volumes while increasing the skin dose and should be included within the body contour to ensure an accurate planning dose. The end-to-end IMRT test using an ART anthropomorphic phantom is a valuable tool to identify discrepancies between calculated and delivered radiation doses.

High control voltage and low success rate limit the application of droplet cutting on digital microfluidic chip, hence, the traditional square electrode was designed to crescent electrode to solve these problems in this paper. First, the relationship between the EWOD tension of micro-droplet and the chord length of effective Triple Contact Line (TCL) was analyzed based on the theory of electrowetting-on-dielectric. Then, the droplet cutting processes of different electrodes were numerically simulated and the results were analyzed. Finally, the effect of droplet cutting on four kinds of chips were tested. The results revel that the crescent electrode can decrease the applied voltage for droplet cutting and the minimum voltage required for cutting on crescent electrode (A=1.41) was at least 13.9% lower than that of square electrode. In addition, the success rates of droplet cutting on crescent electrode at different channel heights are higher than that of square electrode.