Unimodal polyethylenes of high linearity and narrow dispersity by using ortho-4,4′-dichlorobenzhydryl-modified bis(imino)pyridyl-iron catalysts

Six different examples of 4,4′-dichlorobenzhydryl-substituted 2,6-bis(arylimino)pyridyl-iron(ii) chloride complex, [2-{{2,6-((p-ClPh)2CH)2-4-MeC6H2}N = CMe}-6-(ArN CMe)C5H3N]FeCl2 (Ar = 2,6-Me2C6H3Fe1, 2,6-Et2C6H3Fe2, 2,6-iPr2C6H3Fe3, 2,4,6-Me3C6H2Fe4, 2,6-Et2-4-MeC6H2Fe5, 2,6-((p-ClPh)2CH)2-4-MeC6H2Fe6), have been synthesized in good yield and characterized by various spectroscopic and analytical techniques. The molecular structures of Fe2 and Fe5 emphasize the uneven steric protection of the ferrous center imposed by the unsymmetrical N,N,N′-chelate. When treated with either MAO or MMAO (modified-MAO) as activators, Fe1-Fe5 exhibited very high productivities at elevated temperature with peak performance of 21.59 × 106 g PE mol−1(Fe) h−1 for Fe5/MMAO at 50 °C and 15.65 × 106 g PE mol−1(Fe) h−1 for Fe1/MAO at 60 °C. By contrast, the most sterically hindered Fe6 was either inactive (using MAO) or displayed very low activity (using MMAO). As a further feature, this class of iron catalyst was capable of displaying long lifetimes with catalytic activities up to 10.77 × 106 g PE mol−1(Fe) h−1 observed after 1 h. In all cases, strictly linear and unimodal polyethylene was formed with narrow dispersity, while the polymer molecular weight was strongly influenced by the aluminoxane co-catalyst (Mw using MAO > MMAO) and also by the steric properties of the second N-aryl group (up to 32.9 kg mol−1 for Fe3/MAO)

Unimodal polyethylenes of high linearity and narrow dispersity by using ortho-4,4′-dichlorobenzhydryl-modified bis(imino)pyridyl-iron catalysts

Six different examples of 4,4′-dichlorobenzhydryl-substituted 2,6-bis(arylimino)pyridyl-iron(ii) chloride complex, [2-{{2,6-((p-ClPh)2CH)2-4-MeC6H2}N = CMe}-6-(ArN CMe)C5H3N]FeCl2 (Ar = 2,6-Me2C6H3Fe1, 2,6-Et2C6H3Fe2, 2,6-iPr2C6H3Fe3, 2,4,6-Me3C6H2Fe4, 2,6-Et2-4-MeC6H2Fe5, 2,6-((p-ClPh)2CH)2-4-MeC6H2Fe6), have been synthesized in good yield and characterized by various spectroscopic and analytical techniques. The molecular structures of Fe2 and Fe5 emphasize the uneven steric protection of the ferrous center imposed by the unsymmetrical N,N,N′-chelate. When treated with either MAO or MMAO (modified-MAO) as activators, Fe1-Fe5 exhibited very high productivities at elevated temperature with peak performance of 21.59 × 106 g PE mol−1(Fe) h−1 for Fe5/MMAO at 50 °C and 15.65 × 106 g PE mol−1(Fe) h−1 for Fe1/MAO at 60 °C. By contrast, the most sterically hindered Fe6 was either inactive (using MAO) or displayed very low activity (using MMAO). As a further feature, this class of iron catalyst was capable of displaying long lifetimes with catalytic activities up to 10.77 × 106 g PE mol−1(Fe) h−1 observed after 1 h. In all cases, strictly linear and unimodal polyethylene was formed with narrow dispersity, while the polymer molecular weight was strongly influenced by the aluminoxane co-catalyst (Mw using MAO > MMAO) and also by the steric properties of the second N-aryl group (up to 32.9 kg mol−1 for Fe3/MAO)

Rotating Objects via in-Hand Pivoting Using Vision, Force and Touch

We propose a robotic manipulation method that can pivot objects on a surface using vision, wrist force and tactile sensing. We aim to control the rotation of an object around the grip point of a parallel gripper by allowing rotational slip, while maintaining a desired wrist force profile. Our approach runs an end-effector position controller and a gripper width controller concurrently in a closed loop. The position controller maintains a desired force using vision and wrist force. The gripper controller uses tactile sensing to keep the grip firm enough to prevent translational slip, but loose enough to allow rotational slip. Our sensor-based control approach relies on matching a desired force profile derived from object dimensions and weight, as well as vision-based monitoring of the object pose. The gripper controller uses tactile sensors to detect and prevent translational slip by tightening the grip when needed. Experimental results where the robot was tasked with rotating cuboid objects 90 degrees show that the multi-modal pivoting approach was able to rotate the objects without causing lift or translational slip, and was more energy-efficient compared to using a single sensor modality or pick-and-place

Scattering Characteristics Guided Network for ISAR Space Target Component Segmentation

No description supplied</p

Comparison between variable displacement and variable speed compressors for electric vehicle heat pumps

Recent developments in electric vehicles have heightened the need for high-efficiency heat pump technology to improve cruising range and cabinet thermal comfort. As the key component for a heat pump system, compressor has a significant impact on heat pump system performance. In this work, a numerical model of a heat pump system consisting of a variable displacement compressor (VDC) model, a variable speed compressor (VSC) model, and a heat exchanger model is presented to compare the two major types of compressor. The simulation is executed across a diverse array of conditions to assess the performance disparity between two variants of compressors, particularly in challenging environments. The proposed model is validated based on the experimental data from a heat pump test rig which compressor section can be replaced with a prototype VDC or VSC based on validation demands. Overall, the modeling results demonstrate a favorable alignment with the measurements. The simulated power input of VDC under heat and cooling mode has a mean absolute percentage error (MPAE) of 4.4% and 6.0%, respectively, while the MAPEs for VSC under heating and cooling modes are 3.2%, and 4.5%. The modelling results indicate that the VDC system shows superior performance in specific mass flow rate, compressor power input, and system efficiency, especially at part load conditions.</p

Machine Learning-based Battery Life Detection and Photoelectrode Materials Selection for Lithium Batteries

Abstract Herein, we developed three-dimensional pristine titanium dioxide (TiO2) photo-electrocatalyst material (PEM) with homogeneous distribution of oxygen vacancies (OV) for lithium-oxygen (Li-O2) battery system (denoted as LOBs) under illumination. This rationally designed OV-TiO2 photoelectrode-catalyst has exhibited excellent capacity, small overpotential, long-term cycle stability, and higher rate capability performance according to our electrochemical experiment study. In short, OV as photoinduced charge separation centers (inert surface atomic modification method) fascinate the effective separation of electrons (e−) and holes (h+). In turn, induced e− and h+ are beneficial to the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) process. More importantly, machine learning (ML) algorithms to analyze and optimize battery performance are innovative in the photoelectrical field. The utility of ML analysis is extensively shown to be effective in learning the in/output connection of interest. Based on ML analysis results, the OV-TiO2 cathode is indeed the key point to extend the LOB life span. More importantly, our brilliant anatase OV-TiO2 revealed the optimization of electrode material for high performance and reversibility in LOBs. We expect that it will bring special OV-TiO2 and some other hierarchical hollow nanomaterials, a big step toward battery technology no matter in cost-effectiveness and environmentally friendly aspects

Precision tuning of rare-earth-doped upconversion nanoparticlesviadroplet-based microfluidic screening

Rare-earth-doped upconversion nanoparticles (UCNPs) show great promise in a range of applications, including biological imaging and sensing, solar cells and security inks. Although their emission color can be tuned widely as a function of host matrix and dopant composition, the high dimensionality of the associated parameter space and the sensitivity of emission to these parameters make optimization and precision tuning difficult. Herein, we present a new time-efficient synthetic route to NaYF4:Yb,Er,Tm UCNPs and a high-throughput microfluidic reactor to synthesize and precisely tune the emission characteristics of the particlesin situand in real time. We synthesize a range of particles with optimized emission intensity and wide color distribution by changing the doping degree of sensitizer Yb to provide for green-orange tunability, and the ratio of Tm-Er to give green-blue tunability. With the two tunable dimensions, we realize true white light emitting UCNPs based on optimized red, green and blue (RGB) emission ratios from a single composition NaYF4:Yb,Er,Tm nanocrystal—a demanding task for such materials—with CIE 1931 coordinates of (0.29, 0.34) and doping degrees of 60% Yb, 0.45% Er, and 1.05% Tm. Finally, we demonstrate the efficacy of these materials in a thin film format through the fabrication of an anti-counterfeit device.</p

Factors determining the efficiency of porcine somatic cell nuclear transfer : data analysis with over 200,000 reconstructed embryos

Data analysis in somatic cell nuclear transfer (SCNT) research is usually limited to several hundreds or thousands of reconstructed embryos. Here, we report mass results obtained with an established and consistent porcine SCNT system (handmade cloning [HMC]). During the experimental period, 228,230 reconstructed embryos and 82,969 blastocysts were produced. After being transferred into 656 recipients, 1070 piglets were obtained. First, the effects of different types of donor cells, including fetal fibroblasts (FFs), adult fibroblasts (AFs), adult preadipocytes (APs), and adult blood mesenchymal (BM) cells, were investigated on the further in vitro and in vivo development. Compared to adult donor cells (AFs, APs, BM cells, respectively), FF cells resulted in a lower blastocyst/reconstructed embryo rate (30.38% vs. 37.94%, 34.65%, and 34.87%, respectively), but a higher overall efficiency on the number of piglets born alive per total blastocysts transferred (1.50% vs. 0.86%, 1.03%, and 0.91%, respectively) and a lower rate of developmental abnormalities (10.87% vs. 56.57%, 24.39%, and 51.85%, respectively). Second, recloning was performed with cloned adult fibroblasts (CAFs) and cloned fetal fibroblasts (CFFs). When CAFs were used as the nuclear donor, fewer developmental abnormalities and higher overall efficiency were observed compared to AFs (56.57% vs. 28.13% and 0.86% vs. 1.59%, respectively). However, CFFs had an opposite effect on these parameters when compared with CAFs (94.12% vs. 10.87% and 0.31% vs. 1.50%, respectively). Third, effects of genetic modification on the efficiency of SCNT were investigated with transgenic fetal fibroblasts (TFFs) and gene knockout fetal fibroblasts (KOFFs). Genetic modification of FFs increased developmental abnormalities (38.96% and 25.24% vs. 10.87% for KOFFs, TFFs, and FFs, respectively). KOFFs resulted in lower overall efficiency compared to TFFs and FFs (0.68% vs. 1.62% and 1.50%, respectively). In conclusion, this is the first report of large-scale analysis of porcine cell nuclear transfer that provides important data for potential industrialization of HMC technology

Reliability of EEG microstate analysis at different electrode densities during propofol-induced transitions of brain states

Electroencephalogram (EEG) microstate analysis is a promising and effective spatio-temporal method that can segment signals into several quasi-stable classes, providing a great opportunity to invertigate short-range and long-range neural dynamics. However, there are still many controversies in terms of reproducibility and reliability when selecting different parameters or datatypes. In this study, five types of electrode configurations (including 91, 64, 32, 19, and 8 channels) , were configured to measure the reliability of microstate analysis at different five electrode densities during the propofol-induced sedation. First, the microstate topography and parameters at different five electrode densities were compared between the baseline (BS) condition and the moderate sedation (MD) condition, respectively. The intraclass correlation coefficient (ICC) and coefficient of variation (CV) were introduced to quantify the consistency of the microstate parameters. Second, the statistical analysis and classification between BS and MD were performed to determine whether the microstate differences between different conditions can remain stable at different electrode densities, and ICC is also calculated between different condition to measure the consistency of the results in a single condition. The results showed that either in BS condition or the MD condition, there were few significant differences of microstate parameters among the configurations of 91, 64, and 32 channels, and the majority differences existed between the configurations of 19 and 8 channels and other channels. The ICC and CV also showed that the consistency among the configurations of 91, 64, and 32 channels was better than that among all 5 types of electrode configurations after involving 19 and 8 channels. Furthermore, the significant differences between the conditions in 91 channels remained stable those in 64 and 32 channels, but it disappeared for the conditions in 19 and 8 channels. In addition, the results of classification and ICC showed that the microstate analysis becomes unreliable with less than 20 electrodes. The findings in this study supports our hypothesis that the microstate analysis of different brain states is more reliable with high electrode densities and it is not recommended to use with a small number of channels for EEG microstate analysis.</p

High Fe^LS(C) electrochemical activity of an iron hexacyanoferrate cathode boosts superior sodium ion storage

Sodium iron hexacyanoferrate (FeHCF) is one of the most promising cathode materials for sodium-ion batteries (SIBs) due to its low cost theoretical capacity. However, the low electrochemical activity of FeLS(C) in FeHCF drags down its practical capacity and potential plateau. Herein, FeHCF with high FeLS(C) electrochemical activity (C-FeHCF) is synthesized via a facile citric acid-assisted solvothermal method. As the cathode of SIBs, C-FeHCF shows superior cycling stability (ca. 87.3% capacity retention for 1000 cycles at 10 C) and outstanding rate performance (ca. 68.5% capacity retention at 50 C). Importantly, the contribution of FeLS(C) to the whole capacity was quantitatively analyzed via combining dQ/dV and discharge curve for the first time, and the index reaches 44.53% for C-FeHCF, close to the theoretical value. In-situ X-ray diffraction proves the structure stability of C-FeHCF during charge–discharge process, ensuring its superior cycling performance. Furthermore, the application feasibility of the C-FeHCF cathode in quasi-solid SIBs is also evaluated. The quasi-solid SIBs with the C-FeHCF cathode exhibit excellent electrochemical performance, delivering an initial discharge capacity of 106.5 mAh g−1 at 5 C and high capacity retention of 89.8% over 1200 cycles. This work opens new insights into the design and development of advanced cathode materials for SIBs and the beyond