Solidification of liquid metal drops during impact

Hot liquid metal drops impacting onto a cold substrate solidify during their subsequent spreading. Here we experimentally study the influence of solidification on the outcome of an impact event. Liquid tin drops are impacted onto sapphire substrates of varying temperature. The impact is visualised both from the side and from below, which provides a unique view on the solidification process. During spreading an intriguing pattern of radial ligaments rapidly solidifies from the centre of the drop. This pattern determines the late-time morphology of the splat. A quantitative analysis of the drop spreading and ligament formation is supported by scaling arguments. Finally, a phase diagram for drop bouncing, deposition and splashing as a function of substrate temperature and impact velocity is provided

Quantifying Cell Adhesion through Impingement of a Controlled Microjet

The impingement of a submerged, liquid jet onto a cell-covered surface allows assessing cell attachment on surfaces in a straightforward and quantitative manner and in real time, yielding valuable information on cell adhesion. However, this approach is insufficiently characterized for reliable and routine use. In this work, we both model and measure the shear stress exerted by the jet on the impingement surface in the micrometer-domain, and subsequently correlate this to jet-induced cell detachment. The measured and numerically calculated shear stress data are in good agreement with each other, and with previously published values. Real-time monitoring of the cell detachment reveals the creation of a circular cell-free area upon jet impingement, with two successive detachment regimes: 1), a dynamic regime, during which the cell-free area grows as a function of both the maximum shear stress exerted by the jet and the jet diameter; followed by 2), a stationary regime, with no further evolution of the cell-free area. For the latter regime, which is relevant for cell adhesion strength assessment, a relationship between the jet Reynolds number, the cell-free area, and the cell adhesion strength is proposed. To illustrate the capability of the technique, the adhesion strength of HeLa cervical cancer cells is determined ((34 ± 14) N/m2). Real-time visualization of cell detachment in the dynamic regime shows that cells detach either cell-by-cell or by collectively (for which intact parts of the monolayer detach as cell sheets). This process is dictated by the cell monolayer density, with a typical threshold of (1.8 ± 0.2) × 109 cells/m2, above which the collective behavior is mostly observed. The jet impingement method presents great promises for the field of tissue engineering, as the influence of both the shear stress and the surface characteristics on cell adhesion can be systematically studie

Oblique drop impact onto a deep liquid pool

\u3cp\u3eOblique impact of drops onto a solid or liquid surface is frequently observed in nature. Most studies on drop impact and splashing, however, focus on perpendicular impact. Here we study oblique impact of 100μm drops onto a deep liquid pool, where we quantify the splashing threshold, maximum cavity dimensions and cavity collapse by high-speed imaging above and below the water surface. Gravity can be neglected in these experiments. Three different impact regimes are identified: smooth deposition onto the pool, splashing in the direction of impact only, and splashing in all directions. We provide scaling arguments that delineate these regimes by accounting for the drop impact angle and Weber number. The angle of the axis of the cavity created below the water surface follows the impact angle of the drop irrespectively of the Weber number, while the cavity depth and its displacement with respect to the impact position do depend on the Weber number. Weber number dependency of both the cavity depth and displacement is modeled using an energy argument.\u3c/p\u3

One Year of Romosozumab Followed by Two Years of Denosumab Maintains Fracture Risk Reductions: Results of the FRAME Extension Study

Romosozumab, a humanized monoclonal antibody that binds and inhibits sclerostin, has the dual effect of increasing bone formation and decreasing bone resorption. As previously reported in the pivotal FRActure study in postmenopausal woMen with ostEoporosis (FRAME), women with a T-score of ≤ -2.5 at the total hip or femoral neck received subcutaneous placebo or romosozumab once monthly for 12 months, followed by open-label subcutaneous denosumab every 6 months for an additional 12 months. Upon completion of the 24-month primary analysis period, eligible women entered the extension phase and received denosumab for an additional 12 months. Here, we report the final analysis results through 36 months, including efficacy assessments of new vertebral, clinical, and nonvertebral fracture; bone mineral density (BMD); and safety assessments. Of 7180 women enrolled, 5743 (80%) completed the 36-month study (2851 romosozumab-to-denosumab; 2892 placebo-to-denosumab). Through 36 months, fracture risk was reduced in subjects receiving romosozumab versus placebo for 12 months followed by 24 months of denosumab for both groups: new vertebral fracture (relative risk reduction [RRR], 66%; incidence, 1.0% versus 2.8%; p < 0.001), clinical fracture (RRR, 27%; incidence, 4.0% versus 5.5%; p = 0.004), and nonvertebral fracture (RRR, 21%; incidence, 3.9% versus 4.9%; p = 0.039). BMD continued to increase for the 2 years with denosumab treatment in both arms. The substantial difference in BMD achieved through 12 months of romosozumab treatment versus placebo was maintained through the follow-up period when both treatment arms received denosumab. Subject incidence of adverse events, including positively adjudicated serious cardiovascular adverse events, were overall balanced between groups. In conclusion, in postmenopausal women with osteoporosis, 12 months of romosozumab led to persistent fracture reduction benefit and ongoing BMD gains when followed by 24 months of denosumab. The sequence of romosozumab followed by denosumab may be a promising regimen for the treatment of osteoporosis. © 2018 American Society for Bone and Mineral Research.status: publishe