A comparative study for tension-reducing effect of Type I and Type II keystone perforator island flap in the human back

The keystone perforator island flap (KPIF) is popular in reconstructive surgery. However, despite its versatility, its biomechanical effectiveness is unclear. We present our experience of KPIF reconstruction in the human back and evaluate the tension-reducing effect of the KPIF. Between September 2019 and August 2020, 17 patients (51.82 ± 14.72 years) underwent KPIF reconstruction for back defects. In all cases, we measured wound tension at the defect and donor sites before and after KPIF reconstruction using a tensiometer. All defects occurred after complete excision of complicated epidermoid cysts and debridement of surrounding tissues. The defects were successfully covered with Type IIA KPIFs. All flaps survived, and there were no significant postoperative complications. The mean “tension change at the defect after Type I KPIF” and “tension change at the defect after Type II KPIF” were − 2.97 ± 0.22 N and − 5.59 ± 0.41 N, respectively, (P < 0.001). The mean “rate of tension change at the defect after Type I KPIF” and “rate of tension change at the defect after Type II KPIF” were − 36.54 ± 1.89% and − 67.98 ± 1.63%, respectively, (P < 0.001). Our findings confirm the stepwise tension-reducing effect of KPIF and clarify the biomechanics of this flap.

Self-Loosening Behavior of the Nut Due to Tension Change Considering the Inclination of Bearing Surface

Self-loosening behavior is a topic which many researchers are tackling and the principle is coming clearer. Self-loosening occurs mainly when transverse load is applied to the bolt/nut system and the loosening also occurs when such other loads are applied as impact of the bolt (NAS3350 test type) or temperature difference between bolt and nut. The author reproduced the phenomena by using finite element analyses and found the self-loosening is caused by radial relative displacement between bolt and nut threads. On the other hand, some researchers say the self-loosening occur when the tension changes repeatedly while others say it doesn’t. This axial force phenomenon is not yet clear even in experiment. In this paper, the self-loosening phenomenon by the tension change is examined using Finite Element Analyses. The results show that the self-loosening depends on the inclination of the bearing surface. The loosening does not occur when the inclination of the bearing surface is small enough and it occurs when the inclination is large. As the inclination of the bolt head and nut is allowed within the engineering tolerance and flanges rotate when it fastened making the bolt head or nut bearing surface inclination, the self-loosening may happen for any bolts in nature if tension changes repeatedly.

Surface Activity and Emulsifying Effect of Non-Toxic Starch Nanocrystal

The purpose of this study is to investigate the surface activity of starch nanocrystals (SNC), material derived from starch, and confirm their usefulness as a surfactant. In order to evaluate the surface activity, the surface tension change of suspended SNC solution via the Wilhelmy plate method was measured and the values were compared with various synthetic surfactants. The effect of SNC as emulsifier was evaluated on emulsion formation and physical stability. The surface tension of the SNC-dispersed solution was decreased while its concentration was increased. When the 5.0% (w/v) of SNC was added, the surface tension was decreased from 70.3 to 49.5 mN/m. It was confirmed that the physical stability of the emulsion prepared by adding the SNC was improved compared to that of surface inactivity material (PEG 400). The phase separation was observed within 1 hour after preparation of the emulsion containing PEG 400, but the emulsion containing SNC was stable for 5 hours or more. To summarize this study, SNC, a natural-derived and non-toxic material, exhibits sufficient surface activity, thereby confirming the possibility of being applied to the food and pharmaceutical industry.

Verification of numerical analysis for unwinding cable with time-varying unwinding velocity

In this study, the nonlinear unwinding behavior of cables in a transient state wound in a cylindrical spool package was analyzed using unwinding dynamics. In previous studies, investigations were conducted using constant unwinding velocity. However, this method is limited due to complexities regarding the analysis of the actual behavior where the unwinding velocity increases or decreases. In this paper, to prevent problems, such as twisting, entanglement, and cutting, that occur during the rapid unwinding process, an experimental device that converts unwinding velocity over time was developed. Using a cable unwinding system, high-speed camera, and tension sensor, the equation of motion, which was derived in a previous study using the expanded Hamilton theorem, was experimentally verified. Moreover, the cable’s tension change and behavior in the unwinding process were analyzed, and a method to solve the unwinding problem was studied.

Safety Analysis and Simulation Validation of Hose Whipping Phenomenon in Air Refueling

This paper aims to identify the main cause of the hose whipping phenomenon (HWP) in air refueling, and come up with effective preventive measures. The system-theoretic accident model and process (STAMP), i.e., the system-theoretic process analysis (STPA), was adopted to evaluate the safety of air refueling. Then, the evaluation results were verified with a self-designed simulation validation model. The results show that the HWP is controlled by the docking speed, reel mechanism, and designed hose length; the swing range and tension change of the hose increased under inappropriate speed control; reel control could end the hazardous state of the hose within 50s after docking; the HWP occurred after the hose length was shortened from 22m to 14m. The research findings provide a reference for the prevention of the HWP.

The Hubble Tension: Change in Dark Energy or a Case for Modified Gravity?

Here we propose a modification of the gravitational field on large scales as an alternate explanation for the discrepancy in the value of the Hubble constant as implied by Planck observations of the CMBR in the early Universe and that deduced from other distance indicators in the present epoch.

General Practitioners Are from Mars, Administrators Are from Venus: The Role of Misaligned Occupational Dispositions in Inhibiting Mandated Role Change

Research on mandated occupational role change focuses on jurisdictional conflict to explain change failure. The authors’ study of the English National Health Service highlights the role of occupational dispositions in shaping how mandated role change is implemented by members of multiple occupational groups. The authors find that tension stemming from misaligned dispositions may emerge as members of different occupations interact during their role change implementation efforts. Depending on dispositional responses to tension, change may fail as members of the different occupations avoid interactions. This suggests that effective role change can be elusive even in the initial absence of conflicting occupational interests.