Search

Interlocking metasurfaces (ILMs) are a newly developed joining technology that relies on arrays of interlocking features that transmit force and constrain motion between adjoining bodies in one or more directions. This study explores harnessing the shape memory effect (SME) in Nickel-Titanium shape memory alloys (NiTi SMAs) in structures fabricated using additive manufacturing (AM) to advance the development of active ILMs by creating unit cells that open or close at specific temperatures. The study encompasses designing and fabricating two distinct interlocking array configurations using near-equiatomic NiTi powder and the laser powder bed fusion (L-PBF) AM technique, following a previously developed AM process optimization framework to manufacture defect-free parts. To guide the design process, finite element analysis (FEA) was employed to predict strain values during engage-disengage cycles. The martensitic transformation characteristics of the ILMs were characterized. Thermomechanical testing revealed that the ILMs demonstrate high locking force once engaged, coupled with complete shape recovery and good cyclic stability. Digital image correlation (DIC) was also employed to validate the FEA predictions during the engage-disengage cycles. The results indicate that NiTi SMA-based ILMs can be designed and fabricated into complex shapes using L-PBF. By leveraging the SME, the functionality of an ILM can be improved upon. The combination of computational modeling, additive manufacturing, and thermomechanical and physical property characterization provides a framework for designing future ILMs out of active materials.

Additive manufacturing (AM) or 3D printing is a manufacturing technique in which complex geometries can be fabricated in a layer-by-layer fashion. Yet the flexibility brought about by AM goes beyond [...]

Objective: To find out how much the temperature in the palm rises after upper thoracic sympathectomy for palmar hyperhidrosis, and correlate the temperature with the outcome. Design: Retrospective study. Setting: University hospital, Spain. Subjects: 73 patients (34 women and 39 men, age range 16-42 years, mean 26) who were operated for palmar hyperhidrosis between 1 January 1995 and 31 December 1997. Interventions: Bilateral thoracic endoscopic sympathectomy during which the temperature was monitored on the skin of both axillae and thenar eminences, and in the oesophagus. Main outcome measures: Morbidity, alleviation of hyperhidrosis, recurrence rate, and differences in temperature post\operatively. Results: There was minor bleeding during operation in 25 cases (34%), but in only 4 was it sufficient to require insertion of a drain; 2 patients developed transient Horner's syndrome; but the most common complication was compensatory hyperhidrosis (n = 52, 71%). In only 5 was this other than mild and required treatment with aluminium chloride in ethanol 25%. Palmar hyperhidrosis was alleviated in all cases, axillary sweating was considerably improved, and there was improvement in the feet in 56 (77%). There were 5 recurrences, all on the right side, during a mean follow up of 9 months (range 2-36), but in no case was the sweating severe. In almost all cases the temperature of the palm was less than that of the axilla before operation by a mean (SD) of 0.9 (0.3)°C. The rise in temperature varied from 1.7 (0.4)°C to 2.6 (0.4)°C. In the 5 patients who developed recurrences the increase was less (0.5 (0.4)°C). Conclusion: Thoracic endoscopic sympathectomy is safe, simple, and effective in treating palmar hyperhidrosis that has not responded to conservative treatment. Intradermal monitoring is an accurate and cost-effective way of monitoring temperature during operation. Although it is essential to achieve a rise in temperature of 1°C, our most important finding was that the final temperature in both hands and axillae should be above 35°C and as near as possible to 36°C. [ABSTRACT FROM AUTHOR]

Objective: To assess the prognosis of cancer patients in an intensive care unit (ICU), to compare the capabilities of severity scoring systems to predict hospital death, and to improve prediction by adding new variables., Patients and Methods: Cohort study in a medical-surgical ICU of a university hospital. Demographic and oncologic characteristics were collected along with death records for all nonsurgical cancer patients admitted between January 1995 and June 2000. Severity scores and risk of death were calculated., Results: In the cohort of 250 patients studied, the hospital mortality rate was 58% and the ICU mortality rate was 38.8%. The best predictions were made with the third version of the Acute Physiology and Chronic Health Evaluation (APACHE III), the total maximum Sequential Organ Failure Assessment (SOFA) score, and the total maximum Multiple Organ Dysfunction Score (MODS). The APACHE II and the Simplified Acute Physiology Score (SAPS), version II, were good predictors, whereas the systems of the International Council on Mining and Metals overestimated hospital mortality and the Modality Prediction Model at 0 and 24 hours (MPM0 and MPM24) and the Logistic Organ Dysfunction System underestimated it. The total maximum SOFA and MODS scores had the greatest discriminating capability and the SOFA0, the MODS0, MPM0, and MPM24 had the poorest. All assessment systems except the APACHE III improved when we added new mortality-associated variables: prior functional status, diabetes, radiographic lung infiltrates, mechanical ventilation, and vasoactive support., Conclusions: Medical oncology patients should not all be denied intensive care. None of the systems assessed offer clinically relevant advantages for predicting hospital mortality in nonsurgical oncology patients in the ICU, although we recommend the SAPS II because it includes oncologic variables, is easy to score, and has good prognostic capability.