Wavy Graphene Nanoribbons Containing Periodic Eight-Membered Rings for Light-Emitting Electrochemical Cells.

Precision graphene nanoribbons (GNRs) offer distinctive physicochemical properties that are highly dependent on their geometric topologies, thereby holding great potential for applications in carbon-based optoelectronics and spintronics. While the edge structure and width control has been a popular strategy for engineering the optoelectronic properties of GNRs, non-hexagonal-ring-containing GNRs remain underexplored due to synthetic challenges, despite offering an equally high potential for tailored properties. Herein, we report the synthesis of a wavy GNR (wGNR) embedding periodic eight-membered rings into its carbon skeleton, which is achieved by the A2B2-type Diels-Alder polymerization between dibenzocyclooctadiyne (6) and dicyclopenta[e,l]pyrene-5,11-dione derivative (8), followed by a selective Scholl reaction of the obtained ladder-type polymer (LTP) precursor. The obtained wGNR, with a length of up to 30 nm, is thoroughly characterized by solid-state NMR, FT-IR, Raman, and UV-Vis spectroscopy with the support of DFT calculations. The non-planar geometry of wGNR efficiently prevents the inter-ribbon π-π aggregation, leading to photoluminescence in solution. Consequently, the wGNR can function as an emissive layer for organic light-emitting electrochemical cells (OLECs), offering a proof-of-concept exploration in implementing luminescent GNRs into optoelectronic devices. The fast-responding OLECs employing wGNR will pave the way for advancements in OLEC technology and other optoelectronic devices.

Quantify individual variation of real-time PM2.5 exposure in urban Chinese homes based on a novel method.

Fine particulate matter (PM2.5 ) concentrations show high variations in different microenvironments indoors, which has considerable impact on risk management. However, the real-time variations of PM2.5 exposure associated with per activity/microenvironment and intra-variation among family members remain undefined. In this study, real-time monitors were used to collect real-time PM2.5 data in different microenvironments in 32 households in urban community of China. Peak concentrations of PM2.5 were found in kitchen. The parallel levels of PM2.5 household indoor and outdoor indicated the benefit of clean energies use. To validly assess the health risk of individuals, we proposed a novel method to estimate the real-time exposure of all residents and firstly investigate the intra-variation of PM2.5 exposure among family members. The member who is responsible for cooking in the family had the maximum PM2.5 exposure. The ratios among intraindividual variations demonstrated children usually had lower exposure compared to the adults as they stayed more time in lower polluted microenvironments such as living room and bedroom. The exposure intensity in living room was above 1.0 for most residents, indicating it is warranted to alleviate the air pollution in living room. This study firstly focused on the intra differences of PM2.5 exposure among family members and provided a new insight for indoor air pollution management. The results suggested when adopting measures to reduce exposure, the microenvironments pattern of each member should be taken into consideration. Future work is welcomed to move another big step on this issue to protect the human health.

Detection of Participation and Training Task Difficulty Applied to the Multi-Sensor Systems of Rehabilitation Robots.

In the process of rehabilitation training for stroke patients, the rehabilitation effect is positively affected by how much physical activity the patients take part in. Most of the signals used to measure the patients' participation are EMG signals or oxygen consumption, which increase the cost and the complexity of the robotic device. In this work, we design a multi-sensor system robot with torque and six-dimensional force sensors to gauge the patients' participation in training. By establishing the static equation of the mechanical leg, the man-machine interaction force of the patient can be accurately extracted. Using the impedance model, the auxiliary force training mode is established, and the difficulty of the target task is changed by adjusting the K value of auxiliary force. Participation models with three intensities were developed offline using support vector machines, for which the C and σ parameters are optimized by the hybrid quantum particle swarm optimization and support vector machines (Hybrid QPSO-SVM) algorithm. An experimental statistical analysis was conducted on ten volunteers' motion representation in different training tasks, which are divided into three stages: over-challenge, challenge, less challenge, by choosing characteristic quantities with significant differences among the various difficulty task stages, as a training set for the support vector machines (SVM). Experimental results from 12 volunteers, with tasks conducted on the lower limb rehabilitation robot LLR-II show that the rehabilitation robot can accurately predict patient participation and training task difficulty. The prediction accuracy reflects the superiority of the Hybrid QPSO-SVM algorithm.

Characteristics of rural agritainment sewage in Sichuan, China.

As a new form of rural tourism, agritainment originating from Sichuan food and recreation establishments is now popular all over China. The physico-chemical characteristics of agritainment sewage in Sichuan were surveyed through questionnaires and sample analysis. It was found that 5.3% of agritainment sites discharged black water directly while 25.3% of sites discharged grey water directly in the environment. The annual average ratio of sewage discharge volume to agritainment operating income is 9.24 L/yuan and could be used to predict discharge volume. The annual discharge volume from agritainment in Sichuan was 124 billion litres in 2017 and was 55% higher than that of 2016. The annual sewage discharge volume from agritainment sites in Sichuan ranged from 12 thousand to 38 million litres and the total sewage discharge volume from 24% of agritainment sites represented 77% of the total annual discharge volume. The main pollutants in Sichuan agritainment sewage were total suspended solids (10-2,470 mg/L), total phosphorus (0.07-17.1 mg/L), chemical oxygen demand (144-2,580 mg/L) and anionic surfactant (3.5-411 mg/L) and the percentage of sewage exceeding the standard (Chinese standards GB8918-1996 Class II) of these environmental indicators was up to 45%, 75%, 95% and 80%, respectively. Considering the increasing volume and concentration of agritainment sewage, we urge the public and government to be aware of related water pollution issues. Based on this study, additional surveys of characteristics of agritainment sewage are suggested to be included in the third national pollution source survey in China (2027).

Leaching assessments of toxic metals in waste plasma display panel glass.

UNLABELLED: The plasma display panel (PDP) is rapidly becoming obsolete, contributing in large amounts to the electronic waste stream. In order to assess the potential for environmental pollution due to hazardous metals leached from PDP glass, standardized leaching procedures, chemical speciation assessments, and bioavailability tests were conducted. According to the Toxicity Characteristic Leaching Procedure (TCLP), arsenic in back glass was present at 4.46 ± 0.22 mg/L, close to its regulation limit of 5 mg/L. Zn is not available in the TCLP, but its TCLP leaching concentration in back glass is 102.96 ± 5.34 mg/L. This is because more than 90% of Zn is in the soluble and exchangeable and carbonate fraction. We did not detect significant levels of Ag, Ba, or Cu in the TCLP leachate, and the main fraction of Ag and Ba is residual, more than 95%, while the fraction distribution of Cu changes SEP by SEP. Ethylenediamine tetraacetic acid (EDTA)- and diethylenetriamine pentaacetic acid (DTPA)-extractable Ag, As, Ba, Cu, Zn, and Ni indicate a lower biohazards potential. These results show that, according to the EPA regulations, PDP glass may not be classified as hazardous waste because none of the metals exceeded their thresholds in PDP leachate. However, the concentrations of As and Zn should be lowered in the manufacturing process and finished product to avoid potential pollution problems. IMPLICATIONS: The plasma display panel is rapidly becoming obsolete because of the liquid crystal display. In this study, the leachability of heavy metals contained in the waste plasma display panel glass was first examined by standardized leaching tests, typical chemical speciation assessments, and bioavailability tests, providing fundamental data for waste PDP glass recovery, recycling, and reuse.

Size-Dependent Photocatalytic Reactivity of Conjugated Microporous Polymer Nanoparticles.

Particle size is a critical factor for improving photocatalytic reactivity of conjugated microporous polymers (CMPs) as mass transfer in the porous materials is often the rate-limiting step. However, due to the synthetic challenge of controlling the size of CMPs, the impact of particle size is yet to be investigated. To address this problem, a simple and versatile dispersion polymerization route that can synthesize dispersible CMP nanoparticles with controlled size from 15 to 180 nm is proposed. Leveraging the precise control of the size, it is demonstrated that smaller CMP nanoparticles have dramatically higher photocatalytic reactivity in various organic transformations, achieving more than 1000% enhancement in the reaction rates by decreasing the size from 180 to 15 nm. The size-dependent photocatalytic reactivity is further scrutinized using a kinetic model and transient absorption spectroscopy, revealing that only the initial 5 nm-thick surface layer of CMP nanoparticles is involved in the photocatalytic reactions because of internal mass transfer limitations. This finding substantiates the potential of small CMP nanoparticles to efficiently use photo-generated excitons and improve energy-efficiency of numerous photocatalytic reactions.

Inverted device architecture for high efficiency single-layer organic light-emitting diodes with imbalanced charge transport.

Many wide-gap organic semiconductors exhibit imbalanced electron and hole transport, therefore efficient organic light-emitting diodes require a multilayer architecture of electron- and hole-transport materials to confine charge recombination to the emissive layer. Here, we show that even for emitters with imbalanced charge transport, it is possible to obtain highly efficient single-layer organic light emitting diodes (OLEDs), without the need for additional charge-transport and blocking layers. For hole-dominated emitters, an inverted single-layer device architecture with ohmic bottom-electron and top-hole contacts moves the emission zone away from the metal top electrode, thereby more than doubling the optical outcoupling efficiency. Finally, a blue-emitting inverted single-layer OLED based on thermally activated delayed fluorescence is achieved, exhibiting a high external quantum efficiency of 19% with little roll-off at high brightness, demonstrating that balanced charge transport is not a prerequisite for highly efficient single-layer OLEDs.

Decreasing exciton dissociation rates for reduced voltage losses in organic solar cells.

Enhancing the device electroluminescence quantum efficiency (EQEEL) is a critical factor in mitigating non-radiative voltage losses (VNR) and further improving the performance of organic solar cells (OSCs). While the common understanding attributes EQEEL in OSCs to the dynamics of charge transfer (CT) states, persistent efforts to manipulate these decay dynamics have yielded limited results, with the EQEEL of high-efficiency OSCs typically remaining below 10-2%. This value is considerably lower than that observed in high efficiency inorganic photovoltaic devices. Here, we report that EQEEL is also influenced by the dissociation rate constant of singlet states (kDS). Importantly, in contrast to the traditional belief that advocates maximizing kDS for superior photovoltaic quantum efficiency (EQEPV), a controlled reduction in kDS is shown to enhance EQEEL without compromising EQEPV. Consequently, a promising experimental approach to address the VNR challenge is proposed, resulting in a significant improvement in the performance of OSCs.

Constructing 3D flower-like LaFe bimetal oxides with abundant mesoporous and controllable active sites for high-efficient phosphorus removal: Synthesis, mechanism, and application.

The design of high-performance porous adsorbents for phosphorus removal is a persistently hot topic to maintain a sustainable aquatic ecosystem. In the present study, a self-templating strategy using LaFe cyanometallates (CMs) as precursors was adopted to prepare porous LaFe bimetal oxides with optimizable structure and composition for phosphate adsorption. The results showed that a high supplied LaIII/FeII ratio enabled an adequate coordination polymerization in the preparation of LaFe CM precursor and led to a striking three-dimensional (3D) structure of "twin lotus flower" with high coordinated water content, which resulted in a 3D flower-like LaFe oxide with high surface area and high porosity (mainly in mesopore). The LaFe oxide of LaFe15T possessing the optimal La/Fe ratio (1.5: 1) exhibited the most superior performance of phosphate adsorption, where La was confirmed to be the main active site for phosphate capture via ligand exchange mechanism. The batch and column tests of phosphate adsorption showed that the 3D flower-like LaFe oxides are effective adsorbents for phosphate removal. Therefore, the structure optimization in the template preparation stage is an effective strategy to design porous LaFe bimetal oxides as high-performance phosphorus removal materials.

Potential application of anti-osteoporotic therapy to relieve sarcopenia in the elderly.

Sarcopenia is a progressive and systemic skeletal muscle disorder associated with aging that usually occurs with age in the elderly. Sarcopenia currently lacks effective pharmacological treatment modalities. Multiple pharmacological intervention modalities are available for osteoporosis, a comprehensive disease characterized by decreased systemic bone mass, degradation of bone microarchitecture, and increased bone fragility. Several recent studies have shown an extremely strong correlation between sarcopenia and osteoporosis, leading to the concept of "osteosarcopenia". Therefore, it is possible to alleviate sarcopenia simultaneously by improving osteoporosis.

Enhanced Operational Stability by Cavity Control of Single-Layer Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence.

Highly efficient organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters are realized in recent years, but the device lifetime needs further improvement for practical display or lighting applications. In this work, a device design principle is presented by tuning the optical cavity of single-layer undoped devices, to realize efficient and long-lived TADF OLEDs. Extending the cavity length to the second-order interference maximum by increasing the emissive layer thickness broadens the recombination zone, while the optical outcoupling efficiency remains close to that of the thinner first-order devices. Such a device design leads to efficient and stable single-layer undoped OLEDs with a maximum external quantum efficiency of 16%, an LT90 of 452 h, and an LT50 of 3693 h at an initial luminance of 1000 cd m-2 , which is doubled compared to the first-order counterparts. It is further demonstrated that the widely-used empirical relation between OLED lifetime and light intensity originates from triplet-polaron annihilation, resulting in an extrapolated LT50 at 100 cd m-2 of close to 90 000 h, approaching the demands for practical backlight applications.

Single-Layer Blue Organic Light-Emitting Diodes With Near-Unity Internal Quantum Efficiency.

Efficient organic light-emitting diodes (OLEDs) commonly comprise a multilayer stack including charge-transport and charge- and exciton-blocking layers, to confine charge recombination to the emissive layer. Here, a highly simplified single-layer blue-emitting OLED is demonstrated based on thermally activated delayed fluorescence with the emitting layer simply sandwiched between ohmic contacts consisting of a polymeric conducting anode and a metal cathode. The single-layer OLED exhibits an external quantum efficiency of 27.7% with minor roll-off at high brightness. The internal quantum efficiency approaches unity, demonstrating that highly simplified single-layer OLEDs without confinement layers can achieve state-of-the-art performance, while greatly reducing the complexity of the design, fabrication, and device analysis.

Reduced bimolecular charge recombination in efficient organic solar cells comprising non-fullerene acceptors.

Bimolecular charge recombination is one of the most important loss processes in organic solar cells. However, the bimolecular recombination rate in solar cells based on novel non-fullerene acceptors is mostly unclear. Moreover, the origin of the reduced-Langevin recombination rate in bulk heterojunction solar cells in general is still poorly understood. Here, we investigate the bimolecular recombination rate and charge transport in a series of high-performance organic solar cells based on non-fullerene acceptors. From steady-state dark injection measurements and drift-diffusion simulations of the current-voltage characteristics under illumination, Langevin reduction factors of up to over two orders of magnitude are observed. The reduced recombination is essential for the high fill factors of these solar cells. The Langevin reduction factors are observed to correlate with the quadrupole moment of the acceptors, which is responsible for band bending at the donor-acceptor interface, forming a barrier for charge recombination. Overall these results therefore show that suppressed bimolecular recombination is essential for the performance of organic solar cells and provide design rules for novel materials.

Sorption of chlorophenols onto fruit cuticles and potato periderm.

To better understand the interaction mechanisms of plant surfaces with polar organic compounds, sorption of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol by fruit cuticles (i.e., tomato, apple, and pepper), and potato tuber periderm were investigated. The roles of cuticular components (waxes, cutin, cutan and sugar) on sorption of chlorophenols are quantitatively compared. Cutin and waxes govern the sorption capacity of bulk apple cuticle by hydrophobic interactions. Potato periderm with highest sugar content exhibits the lowest sorption capability for the chlorophenols. With the increase of hydrophobicity (i.e., Kow ) of sorbate, the relative contribution of lipophilic components (wax, cutin and cutan) on total sorption increases, however, the ratios of Koc to Kow decreases due to increasing ionization degree of sorbates.

Well-defined bimetal oxides derived from Prussian blue analogues with regulable active sites for phosphate removal.

Two well-defined CoFe bimetal oxides are prepared from Prussian blue analogues (PBAs) as precursors with designable structures, which are further explored for phosphate removal. A speed-controlled coordination strategy is used to fabricate two CoFe PBA microcrystals with different morphologies, then two regular CoFe oxides are obtained via an intermediate-temperature calcination. CoFeS, a slow-speed coordination product with truncated microcube structure, contains less coordinated water and Fe3+ in its framework, but can create more mesopores and Fe3+ in its oxidative product of CoFeST300. CoFeST300 has been demonstrated to have higher adsorption capacity and affinity for phosphate adsorption compared to that of the fast-speed coordination product, due to its more Fe3+ as effective adsorption sites via ligand exchange. Besides, the inner-sphere complexation mechanism makes CoFeST300 high selectivity for phosphate removal compared to other co-existing anions. The application performance of CoFeST300 is examined by multiple continuous treatment of actual sewage, and the result of all effluent concentrations below 0.5 mg P/L verifies a promising potential of the fabricated adsorbent for phosphorus removal. Thus, design or regulation of the precursors is an efficiency method to fabricate an ideal metal oxide for phosphate adsorption.

Efficiency of Polymer Light-Emitting Diodes: A Perspective.

The various contributions to the external quantum efficiency (EQE) of polymer light-emitting diodes (PLEDs) are discussed. The EQE of an organic light-emitting diode is governed by a number of parameters, such as the electrical efficiency, the photoluminescence quantum yield (PLQY), the optical outcoupling efficiency and the spin statistics for singlet exciton generation. In the last decade, the electrical efficiency has been determined from a numerical PLED device model. More recently, an optical model to simulate the fraction of photons outcoupled to air for PLEDs with a broad recombination zone has been developed. Together with the directly measured PLQY, the EQE of a PLED can then be estimated. However, it has been observed that the measured EQEs of fluorescent PLEDs, including the model system super-yellow poly(p-phenylene vinylene) (SY-PPV) often exceed the expected values. To solve this discrepancy, it is demonstrate that the electrical PLED model has to be expanded by the inclusion of triplet-triplet annihilation (TTA), which is shown to be responsible for a substantial EQE enhancement. Experimentally, it is obtained that TTA contributes to a singlet-exciton generation efficiency of ≈40% in SY-PPV PLEDs, giving rise to an EQE of ≈4% instead of the expected value of 2.5%.

Substantial transition to clean household energy mix in rural China.

The household energy mix has significant impacts on human health and climate, as it contributes greatly to many health- and climate-relevant air pollutants. Compared to the well-established urban energy statistical system, the rural household energy statistical system is incomplete and is often associated with high biases. Via a nationwide investigation, this study revealed high contributions to energy supply from coal and biomass fuels in the rural household energy sector, while electricity comprised ∼20%. Stacking (the use of multiple sources of energy) is significant, and the average number of energy types was 2.8 per household. Compared to 2012, the consumption of biomass and coals in 2017 decreased by 45% and 12%, respectively, while the gas consumption amount increased by 204%. Increased gas and decreased coal consumptions were mainly in cooking, while decreased biomass was in both cooking (41%) and heating (59%). The time-sharing fraction of electricity and gases (E&G) for daily cooking grew, reaching 69% in 2017, but for space heating, traditional solid fuels were still dominant, with the national average shared fraction of E&G being only 20%. The non-uniform spatial distribution and the non-linear increase in the fraction of E&G indicated challenges to achieving universal access to modern cooking energy by 2030, particularly in less-developed rural and mountainous areas. In some non-typical heating zones, the increased share of E&G for heating was significant and largely driven by income growth, but in typical heating zones, the time-sharing fraction was <5% and was not significantly increased, except in areas with policy intervention. The intervention policy not only led to dramatic increases in the clean energy fraction for heating but also accelerated the clean cooking transition. Higher income, higher education, younger age, less energy/stove stacking and smaller family size positively impacted the clean energy transition.

New Rehabilitation Assessment Method of the End-Effector Finger Rehabilitation Robot Based on Multi-Sensor Source.

In the process of rehabilitation, the objectivity and the accuracy of rehabilitation assessment have an obvious impact on the follow-up training. To improve this problem, using a multi-sensor source, this paper attempts to establish a comprehensive assessment method of the finger rehabilitation effect, including three indicators of finger muscle strength, muscle fatigue degree, and range of motion. Firstly, on the basis of the fingertip pressure sensor of the End-Effector Finger Rehabilitation Robot, a mathematical model of finger muscle strength estimation was established, and the estimated muscle strength was scored using the entropy weight method. Secondly, using an sEMG signal sensor, a fatigue monitoring system was designed in the training process, and the fatigue degree was determined on the basis of the change trend of the eigenvalues of MAV and RMS. Lastly, a human-machine motion coupling model was established, and the joint range of motion acquisition and scoring model were obtained on the basis of the motor encoder. According to the above three indicators, using the AHP assessment method to establish a comprehensive rehabilitation assessment method, the effectiveness of the method was verified by experiments. This paper provides a potential new idea and method for objective, accurate, and convenient assessment of finger function rehabilitation, which is of positive significance for alleviating the burden on rehabilitation doctors and improving rehabilitation efficiency.

Removal of phosphorus and ammonium from municipal wastewater treatment plant effluent by manganese ore in a simulated constructed wetland.

Natural manganese ore (NM) is selected as a distinguished constructed wetland (CW) substrate for nutrient pollutants removal, however, the study on municipal wastewater treatment plant (WWTP) effluent treatment remains scarce. The current study was to investigate the sorption characteristics of NM and the removal efficiency of ammonium and phosphorus from one WWTP effluent in a simulated vertical flow NM constructed wetland (NM-VFCW). Results indicated that NM could effectively sorb ammonium and phosphorus within 24 h, and the desorption ratio was less than 7%. The sorption of ammonium and phosphorus enhanced when increasing the particle size of NM, but was not sensitive with temperature. The removal efficiencies for ammonium and phosphorus were 65% and 76% in NM-VFCW, which were 61% and 31% in gravel VFCW. The much higher removal efficiency for phosphorus was mainly attributed to the precipitation of phosphorus which was identified by the SEM and EDS spectrum. Therefore, the manganese ore sand is highlighted as a powerful substrate for simultaneous advanced removal of phosphorus and ammonium in constructed wetland systems.