Time-/dose- series transcriptome data analysis and traditional Chinese medicine treatment of pneumoconiosis.

Pneumoconiosis' pathogenesis is still unclear and specific drugs for its treatment are lacking. Analysis of series transcriptome data often uses a single comparison method, and there are few reports on using such data to predict the treatment of pneumoconiosis with traditional Chinese medicine (TCM). Here, we proposed a new method for analyzing series transcriptomic data, series difference analysis (SDA), and applied it to pneumoconiosis. By comparison with 5 gene sets including existing pneumoconiosis-related genes and gene set functional enrichment analysis, we demonstrated that the new method was not inferior to two existing traditional analysis methods. Furthermore, based on the TCM-drug target interaction network, we predicted the TCM corresponding to the common pneumoconiosis-related genes obtained by multiple methods, and combined them with the high-frequency TCM for its treatment obtained through literature mining to form a new TCM formula for it. After feeding it to pneumoconiosis modeling mice for two months, compared with the untreated group, the coat color, mental state and tissue sections of the mice in the treated group were markedly improved, indicating that the new TCM formula has a certain efficacy. Our study provides new insights into method development for series transcriptomic data analysis and treatment of pneumoconiosis.

Designing dynamic coordination bonds in polar hybrid crystals for a high-temperature ferroelastic transition.

Ferroelastic materials have gained widespread attention as promising candidates for mechanical switches, shape memory, and information processing. Their phase-transition mechanisms usually originate from conventional order-disorder and/or displacive types, while those involving dynamic coordination bonds are still scarce. Herein, based on a strategic molecular design of organic cations, we report three new polar hybrid crystals with a generic formula of AA'RbBiCl6 (A = A' = Me3SO+ for 1; A = Me3SO+ and A' = Me4N+ for 2; A = A' = Me3NNH2+ for 3). Their A-site cations link to the [RbBiCl6]n2n- inorganic framework with lon topology through Rb-O/N coordination bonds, while their significantly different interactions between A'-site cations and inorganic frameworks provide distinct phase-transition behaviour. In detail, the strongly coordinative A'-site Me3SO+ cations prevent 1 from a structural phase transition, while coordinatively free A'-site Me4N+ cations trigger a conventional order-disorder ferroelastic transition at 247 K in 2, accompanied by a latent heat of 0.63 J g-1 and a usual "high → low" second-harmonic-generation (SHG) switch. Interestingly, the A'-site Me3NNH2+ cations in 3 reveal unusual dynamic coordination bonds, driving a high-temperature ferroelastic transition at 369 K with a large latent heat of 18.34 J g-1 and an unusual "low → high" SHG-switching behaviour. This work provides an effective molecular assembly strategy to establish dynamic coordination bonds in a new type of host-guest model and opens an avenue for designing advanced ferroelastic multifunctional materials.

Pd-CeO2 catalyst facilely derived from one-pot generated Pd@Ce-BTC for low temperature CO oxidation.

Due to the capacity to offer abundant catalytic sites within porous solids featuring high surface areas, metal-organic frameworks (MOFs) and their derivatives have garnered considerable attention as prospective catalysts in environmental catalysis. To promote the industrial application of MOFs, there is an urgent need for an effective and environmental-friendly preparation approach. Breaking through the limitation of the traditional two-step preparation method that Pd was introduced to the already prepared Ce-BTC (Pd/Ce-BTC, BTC = 1, 3, 5 benzenetricarboxylate), in this work, we present a novel one-pot solvothermal method for synthesizing the Pd material supported by Ce-BTC (Pd@Ce-BTC). After pyrolysis in N2 flow or air flow, Pd-CeO2 catalysts derived from Pd@Ce-BTC exhibited much higher CO oxidation activity than those from Pd/Ce-BTC. Moreover, Pd/Ce-BTC and Pd@Ce-BTC pyrolyzed in N2 flow (Pd/Ce-BTC-N and Pd@Ce-BTC-N) could better catalyze the oxidation of CO than Pd/Ce-BTC and Pd@Ce-BTC pyrolyzed in air flow (Pd/Ce-BTC-A and Pd@Ce-BTC-A). Further characterizations revealed that the abundant surface Ce3+ species, rich surface adsorbed oxygen species and superior redox properties were the main reasons for the superior CO oxidation activity of Pd@Ce-BTC-N.

Can a Nomogram Predict Survival After Treatment for an Ankylosing Spondylitis Cervical Fracture in a Patient With Neurologic Impairment? A National, Multicenter Study.

BACKGROUND: Ankylosing spondylitis-related cervical spine fracture with neurologic impairment (ASCF-NI) is a rare but often lethal injury. Factors independently associated with survival after treatment remain poorly defined, and identifying patients who are likely to survive the injury remains challenging. QUESTIONS/PURPOSES: (1) What factors are independently associated with survival after treatment among patients with ASCF-NI? (2) Can a nomogram be developed that is sufficiently simple for clinicians to use that can identify patients who are the most likely to survive after injury? METHODS: This retrospective study was conducted based on a multi-institutional group of patients admitted and treated at one of 29 tertiary hospitals in China between March 1, 2003, and July 31, 2019. A total of 363 patients with a mean age of 53 ± 12 years were eventually included, 343 of whom were male. According to the National Household Registration Management System, 17% (61 of 363) died within 5 years of injury. Patients were treated using nonsurgical treatment or surgery, including procedures using the anterior approach, posterior approach, or combined anterior and posterior approaches. Indications for surgery included three-column injury, unstable fracture displacement, neurologic impairment or continuous progress, and intervertebral disc incarceration. By contrast, patients generally received nonsurgical treatment when they had a relatively stable fracture or medical conditions that did not tolerate surgery. Demographic, clinical, and treatment data were collected. The primary study goal was to identify which factors are independently associated with death within 5 years of injury, and the secondary goal was the development of a clinically applicable nomogram. We developed a multivariable Cox hazards regression model, and independent risk factors were defined by backward stepwise selection with the Akaike information criterion. We used these factors to create a nomogram using a multivariate Cox proportional hazards regression analysis. RESULTS: After controlling for potentially confounding variables, we found the following factors were independently associated with a lower likelihood of survival after injury: lower fracture site, more-severe peri-injury complications, poorer American Spinal Injury Association (ASIA) Impairment Scale, and treatment methods. We found that a C5 to C7 or T1 fracture (ref: C1 to C4 and 5; hazard ratio 1.7 [95% confidence interval 0.9 to 3.5]; p = 0.12), moderate peri-injury complications (ref: absence of or mild complications; HR 6.0 [95% CI 2.3 to 16.0]; p < 0.001), severe peri-injury complications (ref: absence of or mild complications; HR 30.0 [95% CI 11.5 to 78.3]; p < 0.001), ASIA Grade A (ref: ASIA Grade D; HR 2.8 [95% CI 1.1 to 7.0]; p = 0.03), anterior approach (ref: nonsurgical treatment; HR 0.5 [95% CI 0.2 to 1.0]; p = 0.04), posterior approach (ref: nonsurgical treatment; HR 0.4 [95% CI 0.2 to 0.8]; p = 0.006), and combined anterior and posterior approach (ref: nonsurgical treatment; HR 0.4 [95% CI 0.2 to 0.9]; p = 0.02) were associated with survival. Based on these factors, a nomogram was developed to predict the survival of patients with ASCF-NI after treatment. Tests revealed that the developed nomogram had good performance (C statistic of 0.91). CONCLUSION: The nomogram developed in this study will allow us to classify patients with different mortality risk levels into groups. This, coupled with the factors we identified, was independently associated with survival, and can be used to guide more appropriate treatment and care strategies for patients with ASCF-NI. LEVEL OF EVIDENCE: Level III, therapeutic study.

Formaldehyde oxidation on Pd/USY catalysts at room temperature: The effect of acid pretreatment on supports.

The complete catalytic oxidation of formaldehyde (HCHO) to CO2 and H2O at room temperature is a green route for indoor HCHO removal. Zeolite is an excellent carrier material for HCHO oxidation due to its large surface area, intricate pores and high adsorption capacity. However, the zeolite-supported noble metal catalysts have currently shown relatively low activity especially at room temperature. In this work, we present a facile acid treatment strategy for zeolite catalysts to improve the hydroxyl concentration and further enhance their catalytic activity for HCHO oxidation. Activity tests illustrated that HCHO could be completely oxidized to CO2 and H2O at a nearly 100% conversion rate with a weight hourly space velocity (WHSV) of 150,000 mL/(g∙hr) at 25°C, when the support of Pd/USY catalysts was pretreated by hydrochloric acid with a concentration of 0.20 mol/L. The characterization results revealed that the active hydroxyl groups originated from the dealumination in the acid treatment play a key role in the HCHO oxidation reaction. The deduced reaction mechanism suggests that bridging hydroxyl groups may oxidize HCHO to dioxymethylene (DOM) species and terminal hydroxyl groups are responsible for the transformation of DOM groups to formate (HCOO) species.

Effects of the nitrogen form ratios on photosynthetic productivity of poplar under condition of phenolic acids.

Phenolic acids can reduce nitrogen utilization rate of poplar, which seriously restrict the productivity of poplar plantation. In this study, three phenolic acid concentrations (T0, T1, and T2) and three ratios of nitrogen forms (NH4+-N to NO3--were 1:3, 1:7, and 1:14) were chosen for orthogonal experiment on poplar (Populus × euramericana "Neva") seedlings to study the effects of the nitrogen form ratios on photosynthetic productivity of poplar under environment of phenolic acids. Results showed that photosynthetic physiology parameters were influenced by both phenolic acid concentration and nitrogen form ratio. The order of net photosynthetic rate (PN) values obtained from 9 treatments were T1-1:3, T0-1:3, T2-1:3, T0-1:7, T1-1:7, T0-1:14, T2-1:7, T1-1:14, and T2-1:14 (from high to low). Under environment of phenolic acids, when poplar were treated with NH4+-N to NO3--N ratio of 1:14, the major limitation factor of photosynthesis was non stomatal factor. When poplar were treated with NH4+-N to NO3-N ratio of 1:3, the major limitation factor of photosynthesis changed to stomatal factor. The leaf nitrogen content and total biomass were obviously positively related with PN (p < 0.05). Phenolic acid inhibited photosynthetic productivity of poplar in a major way and this effect decreased with increase of the content of NH4+-N.

Increasing the ratio of ammonia nitrogen fertilizer in soil can effectively reduce the toxic effect of phenolic acids on poplar and improve the photosynthetic productivity of poplar.

Subtly tuning intermolecular hydrogen bonds in hybrid crystals to achieve ultrahigh-temperature molecular ferroelastic.

Molecular-based ferroic phase-transition materials have attracted increasing attention in the past decades due to their promising potential as sensors, switches, and memory. One of the long-term challenges in the development of molecular-based ferroic materials is determining how to promote the ferroic phase-transition temperature (T c). Herein, we present two new hexagonal molecular perovskites, (nortropinonium)[CdCl3] (1) and (nortropinium)[CdCl3] (2), to demonstrate a simple design principle for obtaining ultrahigh-T c ferroelastic phase transitions. They consist of same host inorganic chains but subtly different guest organic cations featuring a rigid carbonyl and a flexible hydroxyl group in 1 and 2, respectively. With stronger hydrogen bonds involving the carbonyl but a relatively lower decomposition temperature (T d, 480 K), 1 does not exhibit a crystalline phase transition before its decomposition. The hydroxyl group subtly changes the balance of intermolecular interactions in 2via reducing the attractive hydrogen bonds but increasing the repulsive interactions between adjacent organic cations, which finally endows 2 with an enhanced thermal stability (T d = 570 K) and three structural phase transitions, including two ferroelastic phase transitions at ultrahigh T c values of 463 K and 495 K, respectively. This finding provides important clues to judiciously tuning the intermolecular interactions in hybrid crystals for developing high-T c ferroic materials.

Pt Atomic Single-Layer Catalyst Embedded in Defect-Enriched Ceria for Efficient CO Oxidation.

The local coordination structure of metal sites essentially determines the performance of supported metal catalysts. Using a surface defect enrichment strategy, we successfully fabricated Pt atomic single-layer (PtASL) structures with 100% metal dispersion and precisely controlled local coordination environment (embedded vs adsorbed) derived from Pt single-atoms (Pt1) on ceria-alumina supports. The local coordination environment of Pt1 not only governs its catalytic activity but also determines the Pt1 structure evolution upon reduction activation. For CO oxidation, the highest turnover frequency can be achieved on the embedded PtASL in the CeO2 lattice, which is 3.5 times of that on the adsorbed PtASL on the CeO2 surface and 10-70 times of that on Pt1. The favorable CO adsorption on embedded PtASL and improved activation/reactivity of lattice oxygen within CeO2 effectively facilitate the CO oxidation. This work provides new insights for the precise control of the local coordination structure of active metal sites for achieving 100% atomic utilization efficiency and optimal intrinsic catalytic activity for targeted reactions simultaneously.

Optimal Compensation of MEMS Gyroscope Noise Kalman Filter Based on Conv-DAE and MultiTCN-Attention Model in Static Base Environment.

Errors in microelectromechanical systems (MEMS) inertial measurement units (IMUs) are large, complex, nonlinear, and time varying. The traditional noise reduction and compensation methods based on traditional models are not applicable. This paper proposes a noise reduction method based on multi-layer combined deep learning for the MEMS gyroscope in the static base state. In this method, the combined model of MEMS gyroscope is constructed by Convolutional Denoising Auto-Encoder (Conv-DAE) and Multi-layer Temporal Convolutional Neural with the Attention Mechanism (MultiTCN-Attention) model. Based on the robust data processing capability of deep learning, the noise features are obtained from the past gyroscope data, and the parameter optimization of the Kalman filter (KF) by the Particle Swarm Optimization algorithm (PSO) significantly improves the filtering and noise reduction accuracy. The experimental results show that, compared with the original data, the noise standard deviation of the filtering effect of the combined model proposed in this paper decreases by 77.81% and 76.44% on the x and y axes, respectively; compared with the existing MEMS gyroscope noise compensation method based on the Autoregressive Moving Average with Kalman filter (ARMA-KF) model, the noise standard deviation of the filtering effect of the combined model proposed in this paper decreases by 44.00% and 46.66% on the x and y axes, respectively, reducing the noise impact by nearly three times.

Effect of Hydroxyl Groups on Metal Anchoring and Formaldehyde Oxidation Performance of Pt/Al2O3.

Pt/Al2O3 catalysts showing excellent activity and stability have been used in various reactions, including HCHO oxidation. Herein, we prepared Pt-Na/Al2O3 catalysts with a Pt content of 0.05 wt % to reveal the key factors determining the anchoring of Pt as well as the catalytic activity and mechanism of HCHO oxidation. Pt-Na/nano-Al2O3 (denoted as Pt-Na/nAl2O3) catalysts with 0.05 wt % Pt content could completely oxidize HCHO to CO2 at room temperature, which is the lowest Pt content used in HCHO catalytic oxidation to our knowledge. After Na addition, terminal hydroxyl groups (denoted as HO-µter) on nano-Al2O3 were transformed to doubly bridging hydroxyl groups between Na and Al (denoted as HO-µbri(Na-Al)), which atomically dispersed Pt species. Pt anchoring further promoted the regeneration of HO-µbri(Na-Al) by activating O2 and H2O, oxidizing HCHO to CO2 directly by the fast reaction step ([HCOO-] + [OH]a → CO2 + H2O). Our study revealed that the HO-µbri(Na-Al) synergistically generated by HO-µter and Na species provided anchoring sites for Pt species.

Design and Integrated Analysis of a Flexible Support Microstructure with a Honeycomb Sandwich for the Optical Window of a Hypersonic Remote Sensor.

In order to reduce the influence of the optical window on the image quality of a hypersonic visible light optical remote sensor, we propose a method of adding a double-layer semicircular honeycomb core microstructure with flexible support of a high temperature elastic alloy between a window glass and a frame to reduce the influence of complex thermal stress on the surface accuracy of the optical window. An equivalent model of a semicircular honeycomb structure was established, the elastic parameters of the semicircular honeycomb sandwich microstructure were derived by an analytical method, and a numerical verification and finite element simulation were carried out. The results show that the equivalent model is in good agreement with the detailed model. The optical-mechanical-thermal integrated simulation analysis of the optical window assembly with flexible supporting microstructure proves that the semicircular honeycomb sandwich flexible supporting structure has a positive effect on stress attenuation of the window glass and ensures the wave aberration accuracy of the transmitted optical path difference of the optical window (PV < 0.665 λ, RMS < 0.156 λ, λ = 632.8 nm). Combined with the actual optical system, the optical performance of the window assembly under the flexible support structure is verified. The simulation results show that the spatial frequency of the modulation transfer function (MTF) of the optical system after focusing is not less than 0.58 in the range of 0-63 cycle/mm and the relative decline of MTF is not more than 0.01, which meet the imaging requirements of a remote sensor. The study results show that the proposed metal-based double-layer semicircular honeycomb sandwich flexible support microstructure ensures the imaging quality of the optical window under ultra-high temperature conditions.

Revealing the effect of paired redox-acid sites on metal oxide catalysts for efficient NOx removal by NH3-SCR.

Understanding the nature of active sites on metal oxide catalysts in the selective catalytic reduction (SCR) of NO by NH3 (NH3-SCR) is a crucial prerequisite for the development of novel efficient NH3-SCR catalysts. In this work, two CeO2-based SCR catalyst systems with diverse acidic metal oxides-CeO2 interfaces, i.e., Nb2O5-CeO2 (Nb2O5/CeO2 and CeO2/Nb2O5) and WO3-CeO2 (WO3/CeO2 and CeO2/WO3), were prepared and used to reveal the relationship between NH3-SCR activity and surface acidity/redox properties. In combination with the results of the NH3-SCR activity test and various characterizations, it was found that the NH3-SCR performance of Nb2O5-CeO2 and WO3-CeO2 catalysts was highly dependent on the strong interactions between the redox component (CeO2) and acidic component (Nb2O5 or WO3), as well as the amount of paired redox-acid sites. From a quantitative perspective, an activity-surface acidity/redox property relationship was proposed. For both Nb2O5-CeO2 and WO3-CeO2 catalysts systems operated at the more concerned low-temperature range (200 °C), the NH3-SCR activity in low NOx conversion region (< 40%) was mainly dominated by the surface acidity of catalysts, while the NH3-SCR activity in high NOx conversion region (> 40%) was more determined by redox properties.

Ultrasensitive polarized-light photodetectors based on 2D hybrid perovskite ferroelectric crystals with a low detection limit.

Polarized-light photodetectors are the indispensable elements for practical optical and optoelectronic device applications. Two-dimensional (2D) hybrid perovskite ferroelectrics, in which the coupling of spontaneous polarization (Ps) and light favors the dissociation of photo-induced carriers, have taken a booming position within this portfolio. However, polarized-light photodetectors with a low detection-limit remain unexplored in this 2D ferroelectric family. In this work, the high-quality individual crystals of a 2D perovskite ferroelectric, BA2CsPb2Br7 (1, where BA+ is n-butylammonium), were used to fabricate ultrasensitive polarized-light detectors. Its unique bilayered structural motif results in quite strong electric and optical anisotropy with a large absorption ratio of αc/αa ≈ 3.2 (λ = 405 nm). Besides, the presence of ferroelectric Ps also endows high built-in electric field along the polar c-axis that favors photoelectric activities. Under an extremely low detectable limit of 40 nW/cm2, the detector of 1 exhibits a notable dichroism ratio (Iphc/Ipha ≈ 1.5), a large responsivity of ~39.5 mA/W and a specific detectivity of ~1.2 × 1012 Jones. Moreover, crystal-based devices of 1 also exhibit a fast response speed (~300 µs) and excellent anti-fatigue merits. This work highlights great potentials of hybrid perovskite ferroelectrics toward polarized-light photodetection.

3D-to-2D Dimensional Reduction for Exploiting a Multilayered Perovskite Ferroelectric toward Polarized-Light Detection in the Solar-Blind Ultraviolet Region.

Polarized-light detection in solar-blind ultraviolet region is indispensable for optoelectronic applications, whereas new 2D candidates targeted at solar-blind UV range remain extremely scarce. 2D hybrid perovskite ferroelectrics that combine polarization and semiconducting properties are of increasing interest. Here, using the 3D-to-2D dimensional reduction of CH3 NH3 PbCl3 , we designed a multilayered hybrid perovskite ferroelectric, (CH3 CH2 NH3 )2 (CH3 NH3 )2 Pb3 Cl10 , which shows spontaneous polarization and a high Curie temperature (390 K) comparable with that of BaTiO3 (393 K). The wide band gap (ca. 3.35 eV) and anisotropic absorbance stemming from its intrinsic 2D motif, greatly favor its polarization-sensitive activity in UV region. The device displays excellent polarization-sensitive behavior under 266 nm, along with a large dichroic ratio (ca. 1.38) and high on/off current ratio (ca. 2.3×103 ).

A Lead-free Organicnorganic Halide Perovskite Absorber with Photoconductive Response.

Perovskite hybrids of lead organometal halides, (e. g., CH3 NH3 PbX3 , X=Cl, Br, I) have gained wide attention since their spectacular progress on optoelectronic technologies in recent years. However, it still remains the fundamental problem, namely, the existence of the toxic, bioaccumulative, polluting element Pb and the instability of humidity. In particular, the use of toxic Pb severely limits the broad applications and commercialization of lead-containing optoelectronic devices, and finding an alternative that preserves the unique optoelectronic properties of the lead halide perovskite is highly urgent. Bi3+ exhibits isoelectronic behavior similar to that of Pb2+ in terms of ion radius and electronegativity, which is expected as an environmentally friendly alternative for lead. However, 1D Bi-based hybrid organic-inorganic light-absorbing materials with pyridinium are not numerous. Although great progress has been made, the research on photoresponse behavior are still rarely reported. Here, we present a lead-free organic-inorganic hybrid absorber with photoconductive response, (C5 H7 N2 )BiI4 (1, C5 H7 N2 + is 2-aminopyridinium), which displays a narrow optical bandgap of ∼1.8 eV. Equally importantly, 1 not only features highly applicable properties, but is also able to absorb across most of the UV/Vis region of the solar spectrum. Furthermore, high-quality single crystal with sizes up to 7×6×4 mm3 was successfully grown. In addition, 1 exhibited extremely low dark current (2×10-11  A) at the bias of 10 V, which indicates that the indicator of 1 is an order of magnitude lower than other reported perovskite photodetectors. Moreover, photocurrent on/off switches is faster (∼670 ms), indicating that 1 can be a promising photosensitive switch. These intriguing properties, namely the lead-free composition, a small band gap, and the fast photoconductive response, suggest promising applications in the field of optoelectronics.

Surgical Management of Degenerative Lumbar Scoliosis Associated With Spinal Stenosis: Does the PI-LL Matter?

STUDY DESIGN: Retrospective observational cohort study. OBJECTIVES: To compare the benefits of long and short fusion treatments, and to identify factors potentially aiding surgeons' decision making about the surgical management of degenerative lumbar scoliosis associated with spinal stenosis (DLSS). SUMMARY OF BACKGROUND DATA: The comparative effectiveness of long and short segment fusion for the treatment of DLSS remains controversial. METHODS: Fifty-three patients with symptomatic DLSS managed by posterior-only fusion surgery were enrolled in this study. Twenty patients underwent short fusion (fewer than two segments), and 33 patients had more than three segments fused. The radiological outcomes were assessed by radiography. Health-related quality of life data, including visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, were collected at all preoperative and follow-up visits. RESULTS: The short and long fusion groups showed significant differences in the change in the Cobb angle (4.2° vs. 11.2°), lumbar lordosis (3.9° vs. 11.5°), and pelvic incidence minus the lumbar lordosis angle (PI - LL; 3.2° vs. 11.2°). Both the short and long fusion achieved significant changes in low back pain and leg pain. Patients with PI -LLs > 10° had more relief of low back pain after long fusion (VAS 4.0 ±â€Š2.0) than after short fusion (VAS 2.6 ±â€Š1.7). Patients with PI - LLs > 10° showed significantly improved walking ability after long fusion (ODI 1.0 ±â€Š0.8). The improvement in standing ability after short fusion was greater when PI - LL ≤ 10°(ODI 0.9 ±â€Š0.6). CONCLUSION: Long segment fusion can relieve low back pain better and improve walking ability when PI-LL is mismatched, whereas short segment fusion is more advantageous in improving standing ability in cases of more balanced sagittal spinopelvic alignment. LEVEL OF EVIDENCE: 3.

Highly-Anisotropic Dion-Jacobson Hybrid Perovskite by Tailoring Diamine into CsPbBr3 for Polarization-Sensitive Photodetection.

2D materials with inherent attributes of structural anisotropy have been well applied in the field of polarization-sensitive photodetection. However, to explore new 2D members with strong polarized-light responses still remains a challenge. Herein, by alloying diamine molecule into the 3D prototype of CsPbBr3 , a new Dion-Jacobson (DJ) type 2D perovskite of (HDA)CsPb2 Br7 (1, where HDA2+ is 1,6-hexamethylenediammonium), containing both inorganic Cs metal and organic cations is designed. The natural anisotropy characteristics of 1 are solidly elucidated by analyzing crystal structure, electric conductivity, and optical properties. Strikingly, distinct polarization-sensitive responses are observed in 1, owing to its strong anisotropy of optical absorption (the ratio of αc /αb ≈ 2.2). Consequently, crystal-based detectors of 1 exhibit fascinating photo-activities to polarized-light, including high detectivity (1.5 × 109 Jones), large dichroism ratio (Iph c /Iph b ≈ 1.6) and fast responding rate (200 µs). All these polarization-sensitive performances along with intriguing phase stability make 1 a potential candidate for polarized-light detection. This work paves a pathway toward new functionalities of DJ-type 2D hybrid perovskites for their future optoelectronic device applications.

Exploring a lead-free organic-inorganic semiconducting hybrid with above-room-temperature dielectric phase transition.

Recently, organic-inorganic hybrid lead halide perovskites have attracted great attention for optoelectronic applications, such as light-emitting diodes, photovoltaics and optoelectronics. Meanwhile, the flexible organic components of these compounds give rise to a large variety of important functions, such as dielectric phase transitions. However, those containing Pb are harmful to the environment in vast quantities. Herein, a lead-free organic-inorganic hybrid, (C6H14N)2BiCl5 (CHA; C6H14N+ is cyclohexylaminium), has been successfully developed. As expected, CHA exhibits an above-room-temperature solid phase transition at 325 K (T c), which was confirmed by the differential scanning calorimetry measurement and variable temperature single crystal X-ray diffraction analyses. Further analyses indicate the phase transition is mainly governed by the order-disorder transformation of organic cyclohexylaminium cations. Interestingly, during the process of phase transition, the dielectric constant (ε') of CHA shows an obvious step-like anomaly, which displays a low dielectric constant state below T c and a high dielectric constant state above T c. Furthermore, variable temperature conductivity combined with theoretical calculations demonstrate the notable semiconducting feature of CHA. It is believed that our work will provide useful strategies for exploring lead-free organic-inorganic semiconducting hybrid materials with above room temperature dielectric phase transitions.

Distal Adding-On Phenomenon in Lenke IA and Lenke IIA: Risk Analysis and Selection of the Lowest Instrumented Vertebra.

OBJECTIVE: To analyze the risks of the distal adding-on phenomenon and identify the ideal lowest instrumented vertebra (LIV) for Lenke IA and IIA. METHODS: A total of 84 patients with Lenke IA or Lenke IIA treated with posterior all-pedicle-screw instrumentation were enrolled in this cohort study. Radiographs that were obtained before, immediately after, and 2 years after the operation were measured. Patients were grouped based on the occurrence of the adding-on phenomenon. Independent risk factors were evaluated between these 2 groups via univariate analysis and logistic regression analysis. RESULTS: All patients obtained optimal correction of the main thoracic curve and lumbar curve after selective thoracic fusion. Eighteen patients among a total of 84 patients suffered from the distal adding-on phenomenon during the 2-year follow-up. Multivariable analysis revealed that the primary factors were preoperative thoracolumbar or lumbar curve size in supine side-bending films (odds ratio 0.75, P = 0.008), preoperative thoracic kyphosis (T5-T12) (odds ratio 0.743, P = 0.022), and the difference between the LIV and the LSTV (lowest substantial touched vertebra). All 7 (100%) patients whose LIVs were proximal to the LSTV suffered from distal adding-on phenomenon, whereas 7 of 40 (17.5%) suffered from distal adding-on phenomenon when the LIV was distal to the LSTV. Patients whose LIV was distal to the LSTV had the lowest incidence of the distal adding-on phenomenon (10.8%). CONCLUSIONS: An LIV located proximal to the LSTV should be avoided during selective thoracic fusion for Lenke IA and IIA to prevent the distal adding-on phenomenon. For patients who have a small thoracolumbar or lumbar curve size in bending films or a small T5-T12 angle before surgery, the next vertebra distal to the LSTV may be an optimal choice.

Dimensional Reduction of Cs2 AgBiBr6 : A 2D Hybrid Double Perovskite with Strong Polarization Sensitivity.

By dimensional reduction of the 3D motif of Cs2 AgBiBr6 , a lead-free 2D hybrid double perovskite, (i-PA)2 CsAgBiBr7 (1, i-PA=isopentylammonium), was successfully designed. It adopts a quantum-confined bilayered structure with alternating organic and inorganic sheets. Strikingly, the unique 2D architecture endows it highly anisotropic nature of physical properties, including electric conductivity and optical absorption (the ratio αb /αc =1.9 at 405 nm). Such anisotropy attributes result in the strong polarization-sensitive responses with large dichroic ratios up to 1.35, being comparable to some 2D inorganic materials. This is the first study on the hybrid double perovskites with strong polarization sensitivity. A crystal device of 1 also exhibits rapid response speed (ca. 200 µs) and excellent stabilities. The family of 2D hybrid double perovskites are promising optoelectronic candidates, and this work paves a new pathway for exploring new green polarization-sensitive materials.