Using Brillouin scattering, we measured the single-crystal elastic constants (C ij 's) of a prototypical metal-organic framework (MOF): zeolitic imidazolate framework (ZIF)-8 [Znð2-methylimidazolateÞ 2 ], which adopts a zeolitic sodalite topology and exhibits large porosity. Its C ij 's under ambient conditions are (in GPa) C 11 ¼ 9:522ð7Þ, C 12 ¼ 6:865ð14Þ, and C 44 ¼ 0:967ð4Þ. Tensorial analysis of the C ij 's reveals the complete picture of the anisotropic elasticity in cubic ZIF-8. We show that ZIF-8 has a remarkably low shear modulus G min & 1 GPa, which is the lowest yet reported for a single-crystalline extended solid. Using ab initio calculations, we demonstrate that ZIF-8's C ij 's can be reliably predicted, and its elastic deformation mechanism is linked to the pliant ZnN 4 tetrahedra. Our results shed new light on the role of elastic constants in establishing the structural stability of MOF materials and thus their suitability for practical applications.

S U M M A R YWe examine a variety of mechanisms that have been proposed as contributors to the stress fields expressed as intermediate-depth seismicity in subducting slabs. To this end, we study principal stress orientations for a global data set of 1900 intermediate-depth focal solutions, determining the patterns of events characterized primarily by downdip compression, downdip tension, or neither. In regions dominated by downdip principal stresses, we find that conjugate stress axes exhibit preferential slab-normal orientations. Furthermore, we observe a clear trend of thermal control, in which colder slabs exhibit greater components of downdip compression while warmer slabs display greater downdip tension. In those regions not dominated by downdip principal stresses, a significant number of events exhibit lateral stresses in the form of subhorizontal principal axes in the plane of the slab. We conclude that the evidently complementary roles played by lithospheric age and subduction rate in constraining stress regimes support thermomechanical and petrological buoyancy models for control of intermediate-depth stresses. Moreover, observed lateral stresses support the traditional model of a squeezed ping-pong ball and stress patterns overall are consistent with some influence by reactivated fossil faults.

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Background: Healthcare workers in the front line of diagnosis, treatment, and care of patients with coronavirus disease 2019 (COVID-19) are at great risk of both infection and developing mental health symptoms. This study aimed to investigate the following: (1) whether healthcare workers in general hospitals experience higher mental distress than those in psychiatric hospitals; (2) the role played by religion and alexithymic trait in influencing the mental health condition and perceived level of happiness of healthcare workers amidst the stress of the COVID-19 pandemic; and (3) factors that influence the resilience of healthcare workers at 6 weeks' follow-up.Methods: Four-hundred and fifty-eight healthcare workers were recruited from general and psychiatric hospitals, and 419 were followed-up after 6 weeks. All participants filled out the 20-item Toronto Alexithymia Scale, five-item Brief-Symptom Rating Scale, and the Chinese Oxford Happiness Questionnaire.Results: Under the stress of the COVID-19 pandemic, 12.3% of frontline healthcare workers in general hospitals reported having mental distress and perceived lower social adaptation status compared with those working in psychiatric hospitals. Christians/Catholics perceived better psychological well-being, and Buddhists/Taoists were less likely to experience mental distress. The results at 6 weeks of follow-up showed that the perceived lower social adaptation status of general hospital healthcare workers was temporary and improved with time. Christian/Catholic religion and time had independent positive effects on psychological well-being; however, the interaction of Christian/Catholic religion and time had a negative effect.Conclusions: Collectivism and individualism in the cultural context are discussed with regard to alexithymic trait and Buddhist/Taoist and Christian/Catholic religious faiths. Early identification of mental distress and interventions should be implemented to ensure a healthy and robust clinical workforce for the treatment and control of the COVID-19 pandemic.

The subducting Nazca Plate shows a high degree of along‐strike heterogeneity in terms of intermediate‐depth seismicity (∼70–300 km), orientations of slab stress, and volcanism. We compile the intermediate‐depth earthquakes of South America from the Harvard Centroid Moment Tensor (CMT) catalogue to determine along‐strike dip variations, and we explore the variable level of correlation between these observations. Primary results are three‐fold: (1) Consistency among orientation of tension axes, highest level seismicity, and occurrence of volcanism is associated with steeply‐dipping regions (20°–30°). (2) Volcanism and intermediate‐depth seismicity exhibit no direct correlation, suggesting that earthquake faulting is not a necessary condition for transport of dehydrated fluids out to the mantle wedge for initiation of melting. (3) Comparison of slab thermal structures between regions with and without volcanism suggests that for certain wedge widths, the maximum temperature in the mantle wedge is higher for the former than for the latter.