Exploiting the Marangoni Effect To Initiate Instabilities and Direct the Assembly of Liquid Metal Filaments.

Utilization of the Marangoni effect in a liquid metal is investigated, focusing on initiating instabilities to direct material assembly via the Rayleigh-Plateau instability. Thin (2 nm) copper (Cu) films are lithographically patterned onto thick (12 nm) nickel (Ni) strips to induce a surface energy gradient at the maximum wavelength of the filament instability predicted by Rayleigh-Plateau instability analysis. The pattern is irradiated with an 18 ns pulsed laser such that the pattern melts and the resultant Ni-Cu surface tension gradient induces Marangoni flows due to the difference in surface energies. The experimental results, supported by extensive direct numerical simulations, demonstrate that the Marangoni flow exceeds the capillary flow induced by the initial geometry, guiding instabilities such that final nanoparticle location is directed toward the regions of higher surface energy (Ni regions). Our work shows a route for manipulation, by means of the Marangoni effect, to direct the evolution of the surface instabilities and the resulting pattern formation.

The emerging age of endovascular treatment of acute ischaemic stroke and the role of CT angiography in patient work-up: a guide for the radiologist.

Recent trial evidence suggests that for patients suffering large-vessel occlusive stroke, endovascular therapy based on the stent-retriever technique is associated with superior clinical outcomes when compared to intravenous thrombolysis alone. The challenge now is how this service is to be delivered. This may involve both centralisation of services around large cities and development of robust networks to receive patients from district general hospitals situated further afield. Both diagnostic and interventional neuroradiology will need to expand. Furthermore, we suggest that it would be advantageous for radiology departments in those hospitals receiving hyperacute stroke patients to perform computed tomography (CT) angiography in addition to non-contrast CT, which also has implications for service delivery in these units. This could swiftly aid identification of patients who might benefit from thrombectomy and improve decision-making through demonstration of occlusive thrombus and of collateral status.

Instability of Nano- and Microscale Liquid Metal Filaments: Transition from Single Droplet Collapse to Multidroplet Breakup.

We carry out experimental and numerical studies to investigate the collapse and breakup of finite size, nano- and microscale, liquid metal filaments supported on a substrate. We find the critical dimensions below which filaments do not break up but rather collapse to a single droplet. The transition from collapse to breakup can be described as a competition between two fluid dynamic phenomena: the capillary driven end retraction and the Rayleigh-Plateau type instability mechanism that drives the breakup. We focus on the unique spatial and temporal transition region between these two phenomena using patterned metallic thin film strips and pulsed-laser-induced dewetting. The experimental results are compared to an analytical model proposed by Driessen et al. and modified to include substrate interactions. In addition, we report the results of numerical simulations based on a volume-of-fluid method to provide additional insight and highlight the importance of liquid metal resolidification, which reduces inertial effects.

Hierarchical nanoparticle ensembles synthesized by liquid phase directed self-assembly.

A liquid metal filament supported on a dielectric substrate was directed to fragment into an ordered, mesoscale particle ensemble. Imposing an undulated surface perturbation on the filament forced the development of a single unstable mode from the otherwise disperse, multimodal Rayleigh-Plateau instability. The imposed mode paved the way for a hierarchical spatial fragmentation of the filament into particles, previously seen only at much larger scales. Ultimately, nanoparticle radius control is demonstrated using a micrometer scale switch.

The role of CT and staging laparoscopy in the staging of gastric cancer.

AIM: To assess the relative roles of computed tomography (CT) and diagnostic laparoscopy in the staging process of patients with potentially curable gastric cancer. MATERIALS AND METHODS: Fifty-two patients underwent laparoscopy and CT as part of staging; 36 patients underwent surgery without laparoscopy. Pathological findings at laparoscopy or surgery were compared with initial CT reports, and analysis of the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) was performed. RESULTS: Of the patients who underwent laparoscopy and CT, six were staged as positive for peritoneal disease (PD), of which five (83%) were positive for PD at laparoscopy. Forty-six patients were reported at CT as negative for PD, of which 40 (87%) were negative at laparoscopy. Of 36 patients with no advanced disease at CT, who had surgery without diagnostic laparoscopy, nine (25%) were positive at surgery for PD. The overall sensitivity of CT for PD was therefore 25%, the specificity was 99%, the PPV was 86%, and the NPV was 83%. CONCLUSION: CT is not sufficiently sensitive to detect or exclude PD in patients with gastric cancer, although is highly specific. Staging laparoscopy is an essential adjunct to imaging in all patients being considered for curative surgery for gastric cancer.

Spontaneous regression of metastatic melanoma - clinical evidence of the abscopal effect.

INTRODUCTION: Metastatic melanoma is poorly understood. Regression of primary lesions has been associated with poor prognosis, but spontaneous regression of all metastatic disease is clearly beneficial. A patient's own immune responses occasionally appear to stimulate spontaneous regression of metastatic disease in melanoma. PATIENTS AND METHODS: We present six interesting cases of complete or nearly complete spontaneous regression of metastatic melanoma, suggest possible causes and review the literature. RESULTS AND CONCLUSIONS: These cases show clear radiological, pathological or clinical evidence of spontaneous regression of metastatic melanoma. This remains a poorly understood phenomena warranting further investigation and may prove useful in the development of immune mediated solutions.