Droplet impact on immiscible liquid pool: Multi-scale dynamics of entrapped air cushion at short timescales

We have detected unique hydrodynamic topology in thin air film surrounding the central air dimple formed during drop impact on an immiscible liquid pool. The pattern resembles spinodal and finger-like structures typically found in various thin condensed matter systems. However, similar structures in thin entrapped gas films during drop impacts on solids or liquids have not been reported to date. The thickness profile and the associated dewetting dynamics in the entrapped air layer are investigated experimentally and theoretically using high-speed reflection interferometric imaging and linear stability analysis. We attribute the formation of multiscale thickness perturbations, associated ruptures, and finger-like protrusions in the draining air film as a combined artifact of thin-film and Saffman-Taylor instabilities. The characteristic length scales depend on the impact Weber number, the ratio of the liquid pool to droplet viscosity, and the ratio of air-water to air-oil surface tension

Total mercury and methylmercury in commercial marine species from the Goa coast: Constraints on risk assessment and environmental issues

1925-1932Mercury (Hg) is a toxic element which accumulates in fish and other aquatic organisms from various sources and poses potential risk to the consumers. Methylmercury (MeHg), the common organic species of mercury, usually forms in aquatic environments and is known for neurotoxicity. In this study, the concentration of total Hg and MeHg in 12 commercial species of fish, shellfish, prawn, and crab from coastal areas of Goa were investigated. The total Hg contents varied between 18.5 -260 µg/kg; while the concentration of MeHg had a range of 7.2 -129 µg/kg. Both the ranges were well below the values recorded at other polluted coastal sites and also meet the permissible limits for human consumption. The interspecies comparison shows species from pelagic and benthic habitats with different food habits have significant difference in body loads of total Hg and MeHg, which increases across the trophic levels. The exposure to higher level of Hg in sediment is likely responsible for enhanced bio-concentration of Hg in benthic species as compared to the values in pelagic fishes

The impact of immediate breast reconstruction on the time to delivery of adjuvant therapy: the iBRA-2 study

Background: Immediate breast reconstruction (IBR) is routinely offered to improve quality-of-life for women requiring mastectomy, but there are concerns that more complex surgery may delay adjuvant oncological treatments and compromise long-term outcomes. High-quality evidence is lacking. The iBRA-2 study aimed to investigate the impact of IBR on time to adjuvant therapy. Methods: Consecutive women undergoing mastectomy ± IBR for breast cancer July–December, 2016 were included. Patient demographics, operative, oncological and complication data were collected. Time from last definitive cancer surgery to first adjuvant treatment for patients undergoing mastectomy ± IBR were compared and risk factors associated with delays explored. Results: A total of 2540 patients were recruited from 76 centres; 1008 (39.7%) underwent IBR (implant-only [n = 675, 26.6%]; pedicled flaps [n = 105,4.1%] and free-flaps [n = 228, 8.9%]). Complications requiring re-admission or re-operation were significantly more common in patients undergoing IBR than those receiving mastectomy. Adjuvant chemotherapy or radiotherapy was required by 1235 (48.6%) patients. No clinically significant differences were seen in time to adjuvant therapy between patient groups but major complications irrespective of surgery received were significantly associated with treatment delays. Conclusions: IBR does not result in clinically significant delays to adjuvant therapy, but post-operative complications are associated with treatment delays. Strategies to minimise complications, including careful patient selection, are required to improve outcomes for patients

On the dynamics of air craters observed on droplet surface during impact on immiscible liquid pool

We study drop impacts on immiscible liquid pools and investigate the formation of air craters on droplet surface during penetration through the pool using experimental and theoretical analysis. We attribute the formation of air craters to the sudden deceleration of the droplet. Viscous force is the primary contributor to the rapid deceleration that leads to the formation of air craters on the droplet's surface. The droplet response to the external impulsive decelerating force induces oscillatory modes on the droplet surface exposed to the air forming capillary waves that superimpose to form air craters of various shapes and sizes. A critical Weber number based on the diameter exists ($We_c=10$), beyond which significant depth air craters during the penetration process are detectable. We introduce a non-dimensional parameter (${\Gamma}$) that is the ratio of drag force to the capillary force acting on the droplet. We show that droplets forming air craters of significant depths have ${\Gamma}>1$. Further, we also demonstrate that Legendre polynomials can locally approximate the central air crater jet profile. We also decipher that the air crater response time scale ($T$) varies as the square root of impact Weber number ($T{\sim}We^{1/2}$)

Dynamics of droplet impingement on bioinspired surface: insights into spreading, anomalous stickiness and break-up

Inspired by the self-cleaning ability of lotus leaves and stickiness (towards water) of rose petals, we investigate the droplet impact dynamics on such bioinspired substrates. Impact studies are carried out with water droplets for a range of impact velocities on glass, PDMS and soft lithographically fabricated replicas of the lotus leaf and rose petals, which exhibit near identical wetting properties as that of the original biological entities. In this work, we investigate the spreading, dewetting and droplet break-up mechanisms subsequent to impact. Surprisingly, the rose petal and lotus leaf replicas manifest similar impact dynamics. The observation is extremely intriguing and counterintuitive, as rose petal and its replicas are sticky in contrast to lotus leaves. However, these observations are based on experiments performed with sessile water droplets. By contrast, in the current study, we find that rose petal replicas exhibit non-sticky behaviour at the short time scale similar to(O(10(-3)))s similar to that exhibited by lotus leaf replicas. Air entrapment in the micrometre features of bioinspired surfaces prevent frictional dissipation of droplet kinetic energy, leading to contact edge recession. We have also unveiled interesting universal physics that govern the spreading, recession of the contact edge and subsequent break-up modes (ligament or bulb-ligament) of the droplet

Therapeutic mammaplasty is a safe and effective alternative to mastectomy with or without immediate breast reconstruction

Background: Therapeutic mammaplasty (TM) may be an alternative to mastectomy, but few well designed studies have evaluated the success of this approach or compared the short-term outcomes of TM with mastectomy with or without immediate breast reconstruction (IBR). Data from the national iBRA-2 and TeaM studies were combined to compare the safety and short-term outcomes of TM and mastectomy with or without IBR. Methods: The subgroup of patients in the TeaM study who underwent TM to avoid mastectomy were identified, and data on demographics, complications, oncology and adjuvant treatment were compared with those of patients undergoing mastectomy with or without IBR in the iBRA-2 study. The primary outcome was the percentage of successful breast-conserving procedures in the TM group. Secondary outcomes included postoperative complications and time to adjuvant therapy. Results: A total of 2916 patients (TM 376; mastectomy 1532; mastectomy and IBR 1008) were included in the analysis. Patients undergoing TM were more likely to be obese and to have undergone bilateral surgery than those having IBR. However, patients undergoing mastectomy with or without IBR were more likely to experience complications than the TM group (TM: 79, 21·0 per cent; mastectomy: 570, 37·2 per cent; mastectomy and IBR: 359, 35·6 per cent; P < 0·001). Breast conservation was possible in 87·0 per cent of patients who had TM, and TM did not delay adjuvant treatment. Conclusion: TM may allow high-risk patients who would not be candidates for IBR to avoid mastectomy safely. Further work is needed to explore the comparative patient-reported and cosmetic outcomes of the different approaches, and to establish long-term oncological safety