Although topological mechanical metamaterials have been extensively studied from a theoretical perspective, their experimental characterization has been lagging. To address this shortcoming, we present a systematic, laser-assisted experimental characterization of topological kagome lattices, aimed at elucidating their in-plane phononic and topological characteristics. We specifically explore the continuum elasticity limit, which is established when the ideal hinges that appear in the theoretical models are replaced by ligaments capable of supporting bending deformation, as observed for instance in realistic physical lattices. We reveal how the zero-energy floppy edge modes predicted for ideal configurations morph into finite-frequency phonon modes that localize at the edges. By probing the lattices with carefully designed excitation signals, we are able to extract and characterize all the features of a complex, low-frequency acoustic regime in which bulk modes and topological edge modes overlap and entangle in response. The experiments provide unequivocal evidence of the existence of strong asymmetric wave transport regimes at finite frequencies.

Dislocations significantly influence the physical properties of nanomaterials. Nonequilibrium molecular dynamics simulations uncover significant reductions in thermal conductivity when <110> Si nanowires contain axial screw dislocations. The effect can act in combination with other known thermal conductivity limiting mechanisms, and thus can enable the further optimization of the figure of merit for a new family of complex thermoelectric nanomaterials.

Background Diabetes mellitus can occur after acute pancreatitis (AP), but there are currently no tools for evaluating the risk of developing diabetes after an attack of AP. The aim of the study was to develop a nomogram for prediction of new-onset diabetes mellitus after the first attack of AP. Patients and methods We enrolled 616 patients with first-attack AP. We collected and statistically analyzed demographic data (age, BMI, and duration of hospitalization) and laboratory data (glucose, low-density lipoprotein cholesterol, triglyceride, and cholesterol). Results Univariate analysis suggested duration of hospitalization ( P =0.0003), BMI ( P =0.0059), cholesterol ( P =0.0005), triglyceride ( P =0.0005), hemoglobin ( P =0.0229), and glucose ( P <0.001) at admission were significantly associated with newly developed diabetes after the first-attack AP. Multivariate analysis showed that age [odds ratio (OR)=1.01; 95% confidence interval (CI): 1.00–1.03; P =0.045], BMI (OR=1.06; 95% CI: 1.01–1.12; P =0.018), glucose (OR=1.07; 95% CI: 1.02–1.12; P =0.008), triglyceride (OR=1.03; 95% CI: 1.00–1.06; P =0.035), and low-density lipoprotein-cholesterol (OR=1.18; 95% CI: 1.00–1.38; P =0.044) at admission were important predictors. Conclusion The nomogram is a potentially clinically useful tool for predicting new-onset diabetes, which is currently clinically unprecedented. This finding is not confined to the patients with severe AP but is also for patients who have recovered from mild AP. The nomogram must to be validated externally.

Recent progress in topological mechanics have revealed a family of Maxwell lattices that exhibit topologically protected floppy edge modes. These modes lead to a strongly asymmetric elastic wave response. In this paper, we show how topological Maxwell lattices can be used to realize nonreciprocal transmission of elastic waves. Our design leverages the asymmetry associated with the availability of topological floppy edge modes and the geometric nonlinearity built in the mechanical systems response to achieve the desired non-reciprocal behavior, which can be further turned into strongly one-way phonon transport via the addition of on-site pinning potentials. Moreover, we show that the non-reciprocal wave transmission can be switched on and off via topological phase transitions, paving the way to the design of cellular metamaterials that can serve as tunable topologically protected phonon diodes. arXiv:1908.05716v1 [cond-mat.soft]

In this work, we investigate theoretically and demonstrate experimentally the existence of valley-Hall edge states in the in-plane dynamics of honeycomb lattices with bi-valued strut thickness. We exploit these states to achieve non-trivial waveguiding of optical modes that is immune to backscattering from sharp corners. We also present how different types of interfaces can be combined into multi-branch junctions to form complex waveguide paths and realize a variety of structural logic designs with unconventional wave transport capabilities. We illustrate this potential with two applications. The first is a direction-selective energy-splitting waveguide tree featuring a pronounced asymmetric wave transport behavior. The second is an internal waveguide loop along which the energy can be temporarily trapped and periodically released, effectively working as a signal delayer. The modal complexity of in-plane elasticity has important consequences on the regime of manifestation of the edge states, as the availability of viable total bandgaps is shifted to higher frequencies compared to the out-of-plane counterpart problem. It also poses additional experimental challenges, associated with proper acquisition and deciphering of the in-plane modes, the solution of which requires a systematic use of in-plane laser vibrometry.

The carbon nanotubes' resilience to mechanical deformation is a potentially important feature for imparting tunable properties at the nanoscale. Using nonequilibrium molecular dynamics and empirical interatomic potentials, we examine the thermal conductivity variations with bending in the thermal transport regime where both ballistic and diffusive effects coexist. These simulations are enabled by the realistic atomic-scale descriptions of uniformly curved and buckled nanotube morphologies obtained by imposing objective boundary conditions. We uncover a contrasting behavior. At shorter lengths, the phonon propagation is affected significantly by the occurrence of localized structural buckling. As the nanotube length becomes comparable with the phonon mean free path, heat transport becomes insensitive to the buckling deformations. Our result settles the controversy around the differences between the current experimental and molecular-dynamics measurements of the thermal transport in bent nanotubes.

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Sequential invasive-noninvasive ventilation (NIV) improves the outcomes of patients with respiratory failure caused by acute exacerbation of chronic obstructive pulmonary disease (AECOPD); however, there is no clear consensus on the optimal timing of the switch to sequential invasive-NIV in these patients. In the present study, a potential role for the modified Glasgow Coma Scale (GCS) score to guide sequential weaning was investigated. Patients with AECOPD and respiratory failure were prospectively recruited from three study centers (Wenling Hospital Affiliated to Wenzhou Medical University, the First Affiliated Hospital of Wenzhou Medical University and Changsha Central Hospital) between January 1st 2016 and December 31st 2018. Patients were randomly assigned to group A and B, with the switching point for sequential weaning strategy in the two groups being a modified GCS score ≥13 and 10 points, respectively. Each group included 240 patients. Baseline demographic characteristics were comparable in the two groups. The duration of invasive mechanical ventilation (IMV) in group A was significantly shorter than that in group B. However, there were no significant between-group differences with respect to the incidence of re-intubation, ventilator-associated pneumonia, in-hospital mortality or the length of hospital stay. Use of a modified GCS score ≥13 as the switching point for sequential invasive-NIV may help decrease the duration of IMV in patients with AECOPD and respiratory failure.