Isotropic negative thermal expansion and its mechanism in tetracyanidoborate salt CuB(CN)4

The control of thermal expansion is essential in applications where thermal stability is required from fiber optics coatings, high performance fuel cell cathodes to tooth fillings. Negative thermal expansion (NTE) materials, although rare, are fundamental for this purpose. This work focuses on studying tetracyanidoborate salt CuB(CN)4, an interesting cubic-structure material that displays large isotropic NTE. A joint study of synchrotron X-ray diffraction, temperature-dependent Raman spectroscopy, and lattice dynamics calculations was conducted, showing that not only low-frequency optical modes (transverse thermal vibrations of N and C atoms) but also the acoustic modes (the vibrations of Cu atoms as a collective torsion of the neighboring atoms), contribute to NTE. As a result, new insights were gained into the NTE mechanism of CuB(CN)4 and related framework materials

Effects of microalgae as diets on the survival, development and fecundity of a pelagic cyclopoid copepod Apocyclops borneoensis

It has been proposed that the feeding habit of cyclopoids is different from that of calanoid copepods in that they feed mainly on microalgae during early development but become carnivorous later. However, a different view also exists, believing that microalgae are the prime food for some cyclopoid copepods. In the present study, microalgae from various taxonomic groups, including a dinoflagellate (Prorocentrum micans), three diatoms (Chaetoceros muelleri, Skeletonema costatum and Nitzschia closterium f. minutissima), and a prymnesiod (Isochrysis galbana), were offered at different concentrations to the cyclopoid copepod, Apocyclops borneoensis, with survival, development and reproduction of the copepod closely monitored. The results showed that A. borneoensis is capable of utilizing any of the microalgae species tested for development and reproduction, but significant differences in survival, development rates of both nauplii and copepodites, and fecundity were detected among species. The results also showed that within a same algal species, food concentration also significantly affected various biological parameters measured. Overall, C. muelleri and I. galbana were the better diets for A. borneoensis and their optimal food concentration ranged from 8.50 to 17.00 mg C ml21. The optimal food concentration of P. micans was also found to be 8.50–17.00 mg C ml21, however for the other two algae, S. costatum and N. closterium f. minutissima, it was lower at 1.70–8.50 mg Cml21. The present study provides novel information on the feeding habit of A. borneoensis and the effects of both quality and quantity of microalgae diets on a range of biological parameters are described

Effects of microalgae as diets on the survival, development and fecundity of a pelagic cyclopoid copepod Apocyclops borneoensis

It has been proposed that the feeding habit of cyclopoids is different from that of calanoid copepods in that they feed mainly on microalgae during early development but become carnivorous later. However, a different view also exists, believing that microalgae are the prime food for some cyclopoid copepods. In the present study, microalgae from various taxonomic groups, including a dinoflagellate (Prorocentrum micans), three diatoms (Chaetoceros muelleri, Skeletonema costatum and Nitzschia closterium f. minutissima), and a prymnesiod (Isochrysis galbana), were offered at different concentrations to the cyclopoid copepod, Apocyclops borneoensis, with survival, development and reproduction of the copepod closely monitored. The results showed that A. borneoensis is capable of utilizing any of the microalgae species tested for development and reproduction, but significant differences in survival, development rates of both nauplii and copepodites, and fecundity were detected among species. The results also showed that within a same algal species, food concentration also significantly affected various biological parameters measured. Overall, C. muelleri and I. galbana were the better diets for A. borneoensis and their optimal food concentration ranged from 8.50 to 17.00 mg C ml21. The optimal food concentration of P. micans was also found to be 8.50–17.00 mg C ml21, however for the other two algae, S. costatum and N. closterium f. minutissima, it was lower at 1.70–8.50 mg Cml21. The present study provides novel information on the feeding habit of A. borneoensis and the effects of both quality and quantity of microalgae diets on a range of biological parameters are described

Pelagic microalgae as suitable diets for the benthic harpacticoid copepod Tigriopus japonicus

It has been reported that certain microalgae have the ability to cause various negative effects on pelagic calanoid copepods. However, whether such pelagic microalgae have similar negative effects on benthic copepods has had little attention. The results of the present study indicated that both benthic naupliar and copepodite stages of the harpacticoid copepod Tigriopus japonicus could effectively utilize five species of pelagic microalgae to complete their development. The effects of different concentrations of various microalgae species on naupliar survival were significant; however, no significant effects on copepodite survival were detected. When fed with two diatoms Chaetoceros muelleri and Skeletonema costatum as well as the dinoflagellate Prorocentrum micans and the chrysophyte Isochrysis galbana at high concentrations (≥8.50 μgC ml⁻¹), the survival of both naupliar and copepodite stages of T. japonicus was more than 90%. However, when the diatom Nitzschia closterium f. minutissima was fed at the high concentrations of 8.50 μgC ml⁻¹, the naupliar survival was 76.3 ± 3.2 %. Interestingly, the negative effects of N. closterium f. minutissima as a diet in the naupliar stage did not affect the survival of the copepodites, which may be explained by increased mobility of copepodites

Analysis on Spatial Characteristics of Supply–Demand Relationship of Amenities in Expanding Central Urban Areas—A Case Study of Huai’an, China

Supply and demand for amenities in expanding urban areas undergo continuous adjustment. In this study, we explored the relationship between supply of and demand for amenities in expanding urban areas to evaluate the rationality and effectiveness of amenity distribution, improve urban governance, and promote urban accessibility and justice, thereby facilitating sustainable urban development. We selected the central urban area of Huai’an City, China as the research area. We used point-of-interest data, Baidu population heatmap data, and residential housing prices to develop supply and demand indices for amenities and analyze the spatial characteristics of the supply of and demand for amenities in expanding urban areas. The results revealed that (1) the supply–demand relationship in the study area was mainly balanced, followed by relationships in which supply was lower than demand, and the relationships of supply exceeding demand is less, accounting for 68.35%, 26.06%, and 5.59%, respectively. (2) The core of the old urban area and the areas surrounding the old urban area had high supply–demand balance, the transitional and new urban areas had less supply than demand, and the developing urban areas had low supply–demand balance; the supply–demand relationship of amenities followed a clear circular distribution pattern. (3) The Chinese government’s continuous renewal of old urban areas has made the quantitative proportion of supply and demand components be positively correlated with the oldness of urban development, which has enlightening effects on the construction of other cities. Finally, we developed suggestions for adjusting the distribution of amenities in the central urban area of Huai’an to facilitate high-quality development in this area

Mechanical and Electromagnetic Wave Absorption Performance of Carbonyl Iron Powder-Modified Nonwoven Materials

In order to develop carbonyl iron-enhanced electromagnetic wave-absorbing composites, this paper utilizes two different morphologies of carbonyl iron powder (CIP), spherical and flake-like, which are blended with aqueous polyurethane (PU) in three different ratios to prepare impregnating solutions. Polyester (PET) needle-punched nonwoven materials are impregnated with these solutions to produce electromagnetic wave-absorbing composites. First, electromagnetic parameters of the two CIP particle types, spherical carbonyl iron (SCIP) and flake-like carbonyl iron (FCIP), are tested with the coaxial method, followed by calculation of the results of their electromagnetic wave absorption performance. Next, the composites are subjected to microscopic morphology observation, tensile testing, and arched frame method electromagnetic wave absorption performance testing. The results indicate that the microwave absorption performance of FCIP is significantly better than that of SCIP. The minimum reflection loss value for F3, a kind of FCIP-modified nonwoven fabric, at the thickness of 1 mm, at 18 GHz is −17 dB. This value is even better than the calculated RL value of CIP at the thickness of 1 mm. The anisotropic shape of flake-like magnetic materials is further strengthened when adhering to the surface of PET fiber material. Additionally, the modified composites with carbonyl iron exhibit higher tensile strength compared with pure PET. The addition of fibrous skeletal materials is expected to enhance the impedance matching of flake-like magnetic particles, forming a wearable and microwave-absorbing composite

Assessment of Right Ventricular-Arterial Coupling by Echocardiography in Patients with Right Ventricular Pressure and Volume Overload

Background: Right ventricle-pulmonary arterial (RV-PA) coupling is considered the gold standard for assessing right ventricular (RV) function and can be evaluated noninvasively by echocardiography. The ratios of tricuspid annular plane systolic excursion/pulmonary artery systolic pressure (TAPSE/PASP), RV global longitudinal strain (G-RVLS)/PASP, and stroke volume/end-systolic volume (SV/ESV) have been proposed as surrogates of RV-PA coupling. The relationship of these parameters remains incompletely understood in patients with volume and pressure loading conditions. We aimed to compare these parameters and evaluate their relationship with 3D RV data in patients with RV pressure and volume overload. Methods: This study was performed on 110 individuals who underwent 2D and 3D echocardiography. Fifty-four patients had RV volume overload (atrial septal defect (ASD) group), 34 patients had RV pressure overload (pulmonary hypertension (PH) group), and 22 were controls. TAPSE/PASP, G-RVLS/PASP and SV/ESV ratios were calculated. Correlations between parameters of RV-PA coupling and 3D data were assessed using general linear mixed models. Results: Compared with the ASD group, the PH group had lower TAPSE/PASP and G-RVLS/PASP ratios. The SV/ESV ratio had a strong correlation with right ventricle ejection fraction (RVEF) in both ASD and PH patients (r = 0.8703, p < 0.001 and r = 0.9388, p < 0.001, respectively). The G-RVLS/PASP ratio showed a strong or moderately negative relationship with end-diastolic volume (EDV), ESV and SV (r = –0.7768, p = 0.001; r = –0.7327, p = 0.0005 and r = –0.6816, p = 0.0018, respectively) in PH patients. The TAPSE/PASP ratio showed moderately negative correlations with EDV and ESV (r = –0.5712, p = 0.0012 and r = –0.5594, p = 0.0016, respectively) in PH patients. Conclusions: Non-invasive RV-PA coupling parameters derived from echocardiography appear similar, but not identical to profiles in pressure-overloaded and volume-overloaded patients. The correlations between non-invasive RV-PA coupling parameters and 3D data displayed various degrees of correlation

Iridium-based electrocatalysts for the acidic oxygen evolution reaction: engineering strategies to enhance the activity and stability

Proton exchange membrane water electrolyzers (PEMWEs) for water electrolysis have received tremendous attention due to their immediate response, high proton conductivity, and low ohmic losses and gas crossover rate. The design of high-performance, economical and long-term durable electrocatalysts in an acidic environment is still the bottleneck to realize the large-scale commercialization of PEMWEs. Iridium-based materials represent one of the most promising classes of oxygen evolution reaction (OER) catalysts due to their intrinsic stability in acid media over ruthenium-based counterparts. However, only a few innovative approaches have been developed for synthesizing iridium-based catalysts (IBCs) in the past decade, possibly due to achieving high activity is detrimental to the stability of IBCs. Accordingly, various engineering strategies of optimizing IBCs have been proposed to address this issue, including doping engineering, morphology engineering, crystal phase engineering and support engineering. Herein, a critical overview focusing on different synthesis and modulation strategies of IBCs is presented, based on an in-depth understanding of the relationship between electronic structures, charge redistribution and activity as well as stability of the electrocatalysts. In addition, the unprecedented achievements in PEMWEs are summarized. The reaction mechanisms and future perspectives are critically discussed to inspire more rational design of IBCs toward practical applications