The proper energy band structure and excellent visible-light responses enable halide perovskites as potential photocatalysts for CO 2 reduction, but the conversion efficiency is still low due to the serious radiative recombination, low CO 2 capturing ability, and poor stability. Here we illustrate the design and synthesis of a halide perovskite@metal−organic framework (MOF) composite photocatalyst with enhanced CO 2 reduction activity. A facile in situ synthetic procedure is employed to directly grow a zinc/cobalt-based zeolitic imidazolate framework (ZIF) coating on the surface of CsPbBr 3 quantum dots. The CsPbBr 3 @ZIF composite shows largely improved moisture stability, CO 2 capturing ability, and charge separation efficiency. Moreover, the catalytic active Co centers in ZIF-67 can further accelerate the charge separation process and activate the adsorbed CO 2 molecules, which leads to enhanced catalytic activity for gaseous CO 2 reduction. This work would provide new insight for designing excellent perovskite/MOF-based catalysts.

A chameleon under pressure: The observed piezochromic behavior of the title compound (BP2VA) was found to depend on its molecular aggregation state and specifically on the strength of the π–π interaction between the anthracene rings of adjacent molecules. When BP2VA is ground or placed under pressure, its molecular aggregation state changes, and a red shift in the fluorescence emission from green via orange to red occurs (see picture).

Measuring the energy intake (kcal) of a person in day-to-day life is difficult. The best laboratory tool achieves 95 % accuracy on average, while tools used in daily living typically achieve 60–80 % accuracy. This paper describes a new method for measuring intake via automated tracking of wrist motion. Our method uses a watch-like device with a micro-electro-mechanical gyroscope to detect and record when an individual has taken a bite of food. Two tests of the accuracy of our device in counting bites found that our method has 94 % sensitivity in a controlled meal setting and 86 % sensitivity in an uncontrolled meal setting, with one false positive per every 5 bites in both settings. Preliminary data from daily living indicates that bites measured by the device are positively related to caloric intake illustrating the potential of the device to monitor energy intake. Future research should seek to further explore the relationship between bites taken and kilocalories consumed to validate the device as an automated measure of energy intake.

This paper is motivated by the growing prevalence of obesity, a health problem affecting over 500 million people. Measurements of energy intake are commonly used for the study and treatment of obesity. However, the most widely used tools rely upon self-report and require a considerable manual effort, leading to underreporting of consumption, noncompliance, and discontinued use over the long term. The purpose of this paper is to describe a new method that uses a watch-like configuration of sensors to continuously track wrist motion throughout the day and automatically detect periods of eating. Our method uses the novel idea that meals tend to be preceded and succeeded by the periods of vigorous wrist motion. We describe an algorithm that segments and classifies such periods as eating or noneating activities. We also evaluate our method on a large dataset (43 subjects, 449 total h of data, containing 116 periods of eating) collected during free-living. Our results show an accuracy of 81% for detecting eating at 1-s resolution in comparison to manually marked event logs of periods eating. These results indicate that vigorous wrist motion is a useful indicator for identifying the boundaries of eating activities, and that our method should prove useful in the continued development of body-worn sensor tools for monitoring energy intake.

A novel divinylanthracene derivative 9,10-bis((E)-2-(pyridin-4-yl)vinyl)anthracene (BP4VA) was synthesized and its two polymorphs with different crystal structures were obtained. The introduction of pyridine in BP4VA leads to multi-stimuli responsive fluorescence. An investigation of the photophysical and stimuli responsive luminescent properties of BP4VA, including the piezochromism and protonation effect, demonstrates that the piezochromic luminescence originates from changes in the molecular aggregation state. Additionally, protonation-deprotonation of the pyridine moieties in BP4VA has a significant effect on the frontier molecular orbitals, resulting in distinct green and red emissions under acid and base stimuli. This study on BP4VA provides a comprehensive insight into the mechanisms within this type of stimuli-responsive luminescent material, and suggests that BP4VA may be a potential candidate for applications in sensing, detection and display devices with remarkable color-changing properties.