Low water pH depressed growth and early development of giant freshwater prawn Macrobrachium rosenbergii larvae

Macrobrachium rosenbergii is one of the shellfish species with high aquaculture value due to its increasing market demand. However, the comparatively low production volume compared to demand coupled with the rapid decline of the natural environment, consequently, drives the potential depletion of the wild population. The decrease in water pH related to anthropogenic pollution is one of the most critical factors affecting the early life performances of M. rosenbergii. Therefore, this study was designed to examine the effect of low water pH on feeding, growth and development of M. rosenbergii early life stages. Experimental water pH was set as neutral (7.7 ± 0.4); mild-acidic (6.4 ± 0.5) and acidic (5.4 ± 0.2) with triplication at a stocking density of 2 larvae/L for 30 days. As expected, M. rosenbergii larvae were highly sensitive to acidic pH with no larvae survived beyond 48 h of exposure. Feeding, survival and growth of larvae were adversely affected by mild-acidic pH exposure as compared to neutral pH. Larvae exposed to mild-acidic water pH experienced a prolonged larval period and only metamorphosed to the post-larval stage at day-30. Whilst under neutral water pH, larval that metamorphosed to post-larval was first observed on day-23. The negative impact of decreased pH, even in mild-acidic pH exposure, on the feeding, survival, growth and development of M. rosenbergii larvae highlights the urgency of periodic pH monitoring during M. rosenbergii larviculture

Effects of shear-thickening polymer on force attenuation capacities in hip protectors

Many elderly people use hip protectors to prevent hip fractures from sideways falls. These hip protectors absorb or shunt away the energy applied to the greater trochanter. Herein, shear-thickening polymer (STP)-based hip protectors composed of STP and polyurethane foam are studied. The purpose of this study was to identify the main factor that reduces the impact force directly applied to the femoral neck region and to determine the optimal thickness of STP in hip protectors. Seven hip protectors of different thicknesses were prepared, and two sets of free-fall mechanical tests with a low impact energy of 25.1 J and moderate impact energy of 44.1 J were conducted for each hip protector. When the thickness of STP exceeded 8 mm, the resultant peak force tended to plateau under both impact conditions, and the force attenuation capacity decreased even under low impact energy conditions. Thus, a hip protector with a 6 mm or 8 mm STP and 5 mm foam was recommended. The STP was the key factor affecting force attenuation capacity, not the polyurethane foam. However, the foam also played an important role in helping the STP function and improving compliance for users.N

Two-Dimensional Dion-Jacobson Tin Perovskite Transistors with Enhanced Ambient Stability

Two-dimensional (2D) layered perovskites have garnered significant research interest within the perovskite community due to their potential as semiconducting materials characterized by high structural stability and favorable optoelectrical properties. Among various contenders, 2D Dion–Jacobson (DJ) perovskites featuring diammonium organic spacers stand out for their exceptional stability. This stability is attributed to the robust hydrogen bonding of the spacer, which leads to a shorter distance between the inorganic octahedral cage layers. In this study, we highlight the remarkable structural stability of 2D DJ perovskite in Sn2+ perovskite thin-film transistors, achieved through the incorporation of 3-(aminomethyl)piperidinium tin iodide (3AMPSnI4) and 4-(aminomethyl)piperidinium tin iodide (4AMPSnI4). The varying positions of the aminomethyl group determine the distortion of the crystal lattice, impacting their respective optical and electrical properties. The relatively low distortion 3AMPSnI4 demonstrates transistor performance with a 10-fold increase in field-effect mobility and 2 orders of magnitude improvement in the on/off current ratio through high film quality with grain size exceeding 10 μm and narrower bandgap. Moreover, the stability of both the film and device under ambient air exposure is markedly improved, with 2D DJ perovskites retaining their crystal structure for over 24 h, presenting a notable enhancement compared to 2D Ruddlesden–Popper perovskites