We discuss finite element simulations and experiments involving the surface tension-driven self-folding of patterned polyhedra. Two-dimensional (2D) photolithographically patterned templates folded spontaneously when solder hinges between adjacent faces were liquefied. Minimization of interfacial free energy of the molten solder with the surrounding fluidic medium caused the solder to ball up, resulting in a torque that rotated adjacent faces and drove folding. The simulations indicate that the folding process can be precisely controlled, has fault tolerance, and can be used to fold polyhedra composed of a variety of materials, ranging in size from the millimeter scale down to the nanometer scale. Experimentally, we have folded metallic, arbitrarily patterned polyhedra ranging in size from 2 mm to 15 microm.

Correction to Figure 2: The x axis was incorrectly labeled with units of nL (where nL ) nanoliter). The correct units should be (× 10 2 pL) (where pL ) picoliter) (i.e., the solder volume units on the x axis should be a factor of 10 smaller than that labeled in Figure 2 of the original article). The simulations used the proper value for the volume, and the change does not affect the discussion or conclusions but is important from a fabrication standpoint.LA803899K

IntroductionExercise-induced bronchoconstriction (EIB) is a prevalent condition in athletes. EIB screening studies identify many athletes with undiagnosed EIB. Moreover, there is a poor relationship between EIB and dyspnea symptoms recalled from memory.PurposeThis study investigated: (I) the prevalence of EIB in British university field hockey athletes; (II) the effect of sex and diagnostic criteria on EIB prevalence; and (III) the association between EIB and contemporaneous dyspnea symptoms.Methods52 field hockey athletes (age: 20 ± 2 years; height: 173 ± 9 cm; body mass: 72 ± 10 kg; male = 31; female = 22) completed a eucapnic voluntary hyperpnea (EVH) test with multi-dimensional dyspnea scores measured 3–10 mins post-EVH. A test was deemed positive (EIB+) if a fall index (FI) ≥10% in FEV1 occurred at two consecutive time points post-test (FIATS). Two further criteria were used to assess the effect of diagnostic criteria on prevalence: FI≥10%, determined by a pre-to-post-EVH fall in FEV1 of ≥10% at any single time-point; and FI≥10%−NORM calculated as FI≥10% but with the fall in FEV1 normalized to the mean ventilation achieved during EVH.ResultsEIB prevalence was 19% and greater in males (30%) than females (5%). In EIB+ athletes, 66% did not have a previous diagnosis of EIB or asthma and were untreated. Prevalence was significantly influenced by diagnostic criteria (P = 0.002) ranging from 19% (FIATS) to 38% (FI≥10%−NORM). Dyspnea symptoms were higher in EIB+ athletes (P ≤ 0.031), produced significant area under the curve for receive operator characteristics (AUC ≥ 0.778, P ≤ 0.011) and had high negative prediction values (≥96%).ConclusionOverall, 19% of university field hockey athletes had EIB, and most were previously undiagnosed and untreated. EVH test diagnostic criteria significantly influences prevalence rates, thus future studies should adopt the ATS criteria (FIATS). Contemporaneous dyspnea symptoms were associated with bronchoconstriction and had high negative prediction values. Therefore, contemporaneous dyspnea scores may provide a useful tool in excluding a diagnosis of EIB.