Efficacy and safety of preoperative immunotherapy in patients with mismatch repair-deficient or microsatellite instability-high gastrointestinal malignancies.

BACKGROUND: Programmed death protein (PD)-1 blockade immunotherapy significantly prolongs survival in patients with metastatic mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) gastrointestinal malignancies such gastric and colorectal cancer. However, the data on preoperative immunotherapy are limited. AIM: To evaluate the short-term efficacy and toxicity of preoperative PD-1 blockade immunotherapy. METHODS: In this retrospective study, we enrolled 36 patients with dMMR/MSI-H gastrointestinal malignancies. All the patients received PD-1 blockade with or without chemotherapy of CapOx regime preoperatively. PD1 blockade 200 mg was given intravenously over 30 min on day 1 of each 21-d cycle. RESULTS: Three patients with locally advanced gastric cancer achieved pathological complete response (pCR). Three patients with locally advanced duodenal carcinoma achieved clinical complete response (cCR), followed by watch and wait. Eight of 16 patients with locally advanced colon cancer achieved pCR. All four patients with liver metastasis from colon cancer reached CR, including three with pCR and one with cCR. pCR was achieved in two of five patients with non-liver metastatic colorectal cancer. CR was achieved in four of five patients with low rectal cancer, including three with cCR and one with pCR. cCR was achieved in seven of 36 cases, among which, six were selected for watch and wait strategy. No cCR was observed in gastric or colon cancer. CONCLUSION: Preoperative PD-1 blockade immunotherapy in dMMR/MSI-H gastrointestinal malignancies can achieve a high CR, especially in patients with duodenal or low rectal cancer, and can achieve high organ function protection.

KRAS, NRAS, BRAF signatures, and MMR status in colorectal cancer patients in North China.

We assessed the clinicopathological features and prognostic values of KRAS, NRAS, BRAF, and DNA mismatch repair status in colorectal cancer (CRC) to provide real-world data in developing countries. We enrolled 369 CRC patients and analyzed the correlation between RAS/BRAF mutation, mismatch repair status with clinicopathological features, and their prognostic roles. The mutation frequencies of KRAS, NRAS, and BRAF were 41.7%, 1.6%, and 3.8%, respectively. KRAS mutations and deficient mismatch repair (dMMR) status were associated with right-sided tumors, aggressive biological behaviors, and poor differentiation. BRAF (V600E) mutations are associated with well-differentiated and lymphovascular invasion. The dMMR status predominated in young and middle-aged patients and tumor node metastasis stage II patients. dMMR status predicted longer overall survival in all CRC patients. KRAS mutations indicated inferior overall survival in patients with CRC stage IV. Our study showed that KRAS mutations and dMMR status could be applied to CRC patients with different clinicopathological features.

Single-cell profiling reveals differences between human classical adenocarcinoma and mucinous adenocarcinoma.

Colorectal cancer is a highly heterogeneous disease. Most colorectal cancers are classical adenocarcinoma, and mucinous adenocarcinoma is a unique histological subtype that is known to respond poorly to chemoradiotherapy. The difference in prognosis between mucinous adenocarcinoma and classical adenocarcinoma is controversial. Here, to gain insight into the differences between classical adenocarcinoma and mucinous adenocarcinoma, we analyse 7 surgical tumour samples from 4 classical adenocarcinoma and 3 mucinous adenocarcinoma patients by single-cell RNA sequencing. Our results indicate that mucinous adenocarcinoma cancer cells have goblet cell-like properties, and express high levels of goblet cell markers (REG4, SPINK4, FCGBP and MUC2) compared to classical adenocarcinoma cancer cells. TFF3 is essential for the transcriptional regulation of these molecules, and may cooperate with RPS4X to eventually lead to the mucinous adenocarcinoma mucus phenotype. The observed molecular characteristics may be critical in the specific biological behavior of mucinous adenocarcinoma.

Thymol Edible Coating Controls Postharvest Anthracnose by Regulating the Synthesis Pathway of Okra Lignin.

Okra has received extensive attention due to its high nutritional value and remarkable functional characteristics, but postharvest diseases have severely limited its application. It is important to further explore the methods and potential methods to control the postharvest diseases of okra. In this study, Colletotrichum fioriniae is the major pathogen that causes okra anthracnose, which can be isolated from naturally decaying okra. The pathogenicity of C. fioriniae against okra was preliminarily verified, and the related biological characteristics were explored. At the same time, an observational study was conducted to investigate the in vitro antifungal effect of thymol edible coating (TKL) on C. fioriniae. After culturing at 28 °C for 5 days, it was found that TKL showed an obvious growth inhibition effect on C. fioriniae. The concentration for 50% of the maximal effect was 95.10 mg/L, and the minimum inhibitory concentration was 1000 mg/L. In addition, it was found that thymol edible coating with a thymol concentration of 100 mg/L (TKL100) may cause different degrees of damage to the cell membrane, cell wall, and metabolism of C. fioriniae, thereby inhibiting the growth of hyphae and causing hyphal rupture. Refer to the results of the in vitro bacteriostatic experiment. Furthermore, the okra was sprayed with TKL100. It was found that the TKL100 coating could significantly inhibit the infection of C. fioriniae to okra, reduce the rate of brown spots and fold on the okra surface, and inhibit mycelium growth. In addition, the contents of total phenols and flavonoids of okra treated with TKL100 were higher than those of the control group. Meanwhile, the activities of phenylalaninammo-nialyase, cinnamic acid-4-hydroxylase, and 4-coumarate-CoA ligase in the lignin synthesis pathway were generally increased, especially after 6 days in a 28 °C incubator. The lignin content of TKL-W was the highest, reaching 65.62 ± 0.68 mg/g, which was 2.24 times of that of CK-W. Therefore, TKL may promote the synthesis of total phenols and flavonoids in okra, then stimulate the activity of key enzymes in the lignin synthesis pathway, and finally regulate the synthesis of lignin in okra. Thus, TKL could have a certain controlling effect on okra anthracnose.

Weak genetic structure of flower thrips Frankliniella intonsa in China revealed by mitochondrial genomes.

Human activities facilitate long-distance dispersal of insects beyond their native range. In particular, the transportation of live plants offers diffusion opportunities for some insects with weak flight abilities. The increase in urban afforestation also help insect reside in urban habitats. The flower thrips, Frankliniella intonsa, is a widespread pest that causes serious damage to many economically important plants. Human activities are likely to facilitate the dispersal of this pest, however, the population genetic structure of this pest remains unclear. Herein, high-throughput sequencing was used to obtain 149 whole mitochondrial genomes of flower thrips from 28 geographic populations in China. Population genetic analyses, phylogenetic reconstruction, and inference of demographic history were then performed. A weak genetic structure was found among all populations across large geographic distance in China, in which five mitochondrial haplotype lineages were resolved. One of the lineages was identified to be shared among most samples collected from central city areas, which may be derived from the surrounding areas. Demographic history analyses suggested a recent population expansion of F. intonsa. Overall, the present population genetic structure of flower thrips in China may be promoted by human-mediated urban afforestation across the country.

Practical synchronization of neural networks with delayed impulses and external disturbance via hybrid control.

This paper studies the problem of practical synchronization for delayed neural networks via hybrid-driven impulsive control in which delayed impulses and external disturbance are taken into account. Firstly, a switching method which establishes the relationship between error signals and a threshold function is introduced, which determines whether time-driven control or event-driven control is activated. Secondly, the effects of delayed impulses and external disturbance on impulsive systems are considered, and the corresponding comparison lemma is proposed. Thirdly, whenever the norm of the initial value of the error system state is less than or greater than the initial value of the threshold function, under the proposed hybrid-driven impulsive control scheme, the practical synchronization of the delayed neural networks with delayed impulses and external disturbance can be achieved by synchronizing impulses. Moreover, the Zeno behavior can be excluded under the proposed hybrid-driven impulsive control. Finally, two numerical examples are presented to verify the effectiveness of the theoretical results.

Exponential Bipartite Synchronization of Fractional-Order Multilayer Signed Networks via Hybrid Impulsive Control.

This article investigates the problem of exponential bipartite synchronization of fractional-order multilayer signed networks via hybrid impulsive control. First, the mathematical model of the networks is established by integrating the fractional dynamics of nodes, the multilayer network edges, and the positive and negative weights (antagonistic relationship), which is more pluralistic and practical. Second, a hybrid impulsive controller is designed, which is composed of the feedback control part and the impulsive control part to realize the exponential bipartite synchronization objective. Both positive and negative impulsive effects are considered and the ranges of the impulsive control gain related to the order of Caputo fractional derivative are discussed. In addition, some sufficient conditions for exponential bipartite synchronization of fractional-order multilayer signed networks are obtained by using the signed graph theory, Lyapunov method, and average impulsive interval method. Furthermore, in order to illustrate the practicability of the theoretical results, fractional-order coupled Chua's circuits model and fractional-order power systems built on multilayer signed networks are established and the exponential bipartite synchronization issues are analyzed. Numerical examples and simulations are provided to show the effectiveness of the obtained results.

Finite-Time Synchronization of Complex Dynamical Networks via a Novel Hybrid Controller.

The issue of finite-time synchronization (FTS) of complex dynamical networks (CDNs) is investigated in this article. A new control strategy coupling weak finite-time control and finite times of impulsive control is proposed to realize the FTS of CDNs, where the impulses are synchronizing and restricted by maximal impulsive interval (MII), differing from the existing results. In this framework, several global and local FTS criteria are established by using the concept of impulsive degree. The times of impulsive control in the controllers and the settling time, which are all dependent on initial values, are derived optimally. A technical lemma is developed, reflecting the core idea of this article. A simulation example is given to demonstrate the main results finally.

MRI measurements predict major low anterior resection syndrome in rectal cancer patients.

PURPOSE: Current low anterior resection syndrome (LARS) score is lagging behind and only based on clinical symptoms patient described. Preoperative imaging indicators which can be used to predict LARS is unknown. We proposed preoperative MRI parameters for identifying major LARS. METHODS: Patients receiving curative restorative anterior resection from Sept. 2007 to Sept. 2015 were collected to complete LARS score (median 75.7 months since surgery). MRI measurements associated with LARS were tested, and a multivariate logistic model was conducted for predicting LARS. Receiver operating characteristic curve was used to evaluate the model. RESULTS: Two hundred fifty-five patients undergoing neoadjuvant chemoradiotherapy and 72 patients undergoing direct surgery were enrolled. The incidence of major LARS in NCRT group was significantly higher (53.3% vs.34.7%, P = 0.005). In patients with neoadjuvant chemoradiotherapy, the thickness of ARJ (TARJ), the distance between the tumor's lower edge and anal rectal joint (DTA), and sex were independent factors for predicting major LARS; ORs were 0.382 (95% CI, 0.198-0.740), 0.653 (95% CI, 0.565-0.756), and 0.935 (95% CI, 0.915-0.955). The AUC of the multivariable model was 0.842 (95% CI, 0.794-0.890). In patients with direct surgery, only DTA was the independent factor for predicting major LARS; OR was 0.958 (95% CI, 0.930-0.988). The AUC was 0.777 (95% CI: 0.630-0.925). CONCLUSIONS: Baseline MRI measurements have the potential to predict major LARS in rectal cancer, which will benefit the decision-making and improve patients' life quality.

Compressed feature vector-based effective object recognition model in detection of COVID-19.

To better understand the structure of the COVID-19, and to improve the recognition speed, an effective recognition model based on compressed feature vector is proposed. Object recognition plays an important role in computer vison aera. To improve the recognition accuracy, most recent approaches always adopt a set of complicated hand-craft feature vectors and build the complex classifiers. Although such approaches achieve the favourable performance on recognition accuracy, they are inefficient. To raise the recognition speed without decreasing the accuracy loss, this paper proposed an efficient recognition modeltrained witha kind of compressed feature vectors. Firstly, we propose a kind of compressed feature vector based on the theory of compressive sensing. A sparse matrix is adopted to compress feature vector from very high dimensions to very low dimensions, which reduces the computation complexity and saves enough information for model training and predicting. Moreover, to improve the inference efficiency during the classification stage, an efficient recognition model is built by a novel optimization approach, which reduces the support vectors of kernel-support vector machine (kernel SVM). The SVM model is established with whether the subject is infected with the COVID-19 as the dependent variable, and the age, gender, nationality, and other factors as independent variables. The proposed approach iteratively builds a compact set of the support vectors from the original kernel SVM, and then the new generated model achieves approximate recognition accuracy with the original kernel SVM. Additionally, with the reduction of support vectors, the recognition time of new generated is greatly improved. Finally, the COVID-19 patients have specific epidemiological characteristics, and the SVM recognition model has strong fitting ability. From the extensive experimental results conducted on two datasets, the proposed object recognition model achieves favourable performance not only on recognition accuracy but also on recognition speed.

Hybrid Event-Triggered and Impulsive Control Strategy for Multiagent Systems With Switching Topologies.

This article investigates the hybrid event-triggered and impulsive consensus problems for leaderless and leader-following multiagent systems (MASs) with switching topologies. Based on the state information of neighboring agents at event-triggered moments and impulsive instants, a hybrid event-triggered and impulsive control strategy (HETICS) is designed to reduce the communication frequency between neighboring agents and to ensure consensus of leaderless and leader-following MASs. By utilizing the Lyapunov direct method, some consensus criteria are obtained for leaderless and leader-following MASs with switching topologies. It is shown that the HETICS excludes the Zeno behavior. Several numerical examples and simulations are given to illustrate the effectiveness of the proposed consensus strategy and a comparison with previous consensus control methods is given.

Event-based master-slave synchronization of complex-valued neural networks via pinning impulsive control.

This paper investigates the synchronization problem of complex-valued neural networks via event-triggered pinning impulsive control (ETPIC). A time-delayed pinning impulsive controller is proposed based on three levels of event-triggered conditions. By employing the Lyapunov functional method and differential inequality technique, sufficient delay-dependent synchronization criteria are derived under the proposed ETPIC scheme. The obtained result shows that synchronization of master and slave complex-valued neural networks can be achieved even if the sizes of delays exceed the length of intervals between any two consecutive impulsive instants determined by Lyapunov-based event-triggered conditions in the proposed control strategy. Moreover, the linear matrix inequality approach is utilized to exclude Zeno behavior. Numerical examples are provided to illustrate the effectiveness of the theoretical results.

A second-order accelerated neurodynamic approach for distributed convex optimization.

Based on the theories of inertial systems, a second-order accelerated neurodynamic approach is designed to solve a distributed convex optimization with inequality and set constraints. Most of the existing approaches for distributed convex optimization problems are usually first-order ones, and it is usually hard to analyze the convergence rate for the state solution of those first-order approaches. Due to the control design for the acceleration, the second-order neurodynamic approaches can often achieve faster convergence rate. Moreover, the existing second-order approaches are mostly designed to solve unconstrained distributed convex optimization problems, and are not suitable for solving constrained distributed convex optimization problems. It is acquired that the state solution of the designed neurodynamic approach in this paper converges to the optimal solution of the considered distributed convex optimization problem. An error function which demonstrates the performance of the designed neurodynamic approach, has a superquadratic convergence. Several numerical examples are provided to show the effectiveness of the presented second-order accelerated neurodynamic approach.

IGAGCN: Information geometry and attention-based spatiotemporal graph convolutional networks for traffic flow prediction.

In this study, a novel spatiotemporal graph convolutional networks model is proposed for traffic flow prediction in urban road networks by fully considering an information geometry approach and attention-based mechanism. Accurate traffic flow prediction in real urban road networks is challenging due to the presence of dynamic spatiotemporal data and external factors in the urban environment. Moreover, the dynamic spatial and temporal dependencies of urban traffic flow data are very important for predicting traffic flow, and it has been shown that a recent attention mechanism has a relatively good ability to capture these dynamic dependencies, which are not fully considered by most existing algorithms. Therefore, in the novel model abbreviated as IGAGCN, the information geometry method is utilized to determine the dynamic data distribution difference between different sensors. The attention mechanism is employed with the information geometry method, in which a matrix is derived by analyzing the distributions of sensor data, and the spatiotemporal dynamic connections in traffic flow data features are better at capturing the spatial dependencies of traffic between different sensors in urban road networks. Furthermore, a parallel sub-model architecture is proposed to consider long time spans, where each dilated causal convolution sub-model is applied to short time spans. Two well-known data sets were employed to demonstrate that our proposed method obtains better performance and is better at capturing the dynamic spatial dependencies of traffic than the existing only-attention-based models. In addition a real-world urban road network in Shenzhen, China, was studied to test and verify the proposed model.

Effect of digestion on bound phenolic content, antioxidant activity and hypoglycemic ability of insoluble dietary fibre from four Triticeae crops.

To assess the physiological functions of bound phenols in insoluble dietary fiber (IDF) from different Triticeae crops, bound phenols in IDF were extracted from wheat, triticale, barley and quinoa. In addition, model in vitro was established and used in evaluating the release of bound phenols and changes in their physiological functions after simulated digestion. Results showed that bound phenol content in IDF from Triticeae crops before digestion was higher than which during digestion, and its physiological functions were also better (p < .05). Moreover, barley extracted before digestion, its bound phenolic content in IDF was higher than those in other three Triticeae crops, besides,its bound phenol also showed better antioxidant ability. Before digestion, bound phenols in IDF from triticale showed the best hypoglycemic ability (the inhibition rate of α-glucosidase was 95%; the inhibition rate of α-amylase was 97%). In the simulated digestion model, the bound phenols were mainly released during the intestinal digestion stage, they showed better physiological functions than which released at the gastric digestion stage. The bound phenol content in triticale was higher and its physiological functions was better than those in the other crops. PRACTICAL APPLICATIONS: The results of this experiment showed that the release of bound phenols measured by chemical extraction (i.e., before digestion) was higher than that by simulated gastrointestinal digestion. Compared with the chemical extraction method, in vitro gastro-intestinal digestion simulates the pH value and enzyme environment of food in the human body gastrointestinal digestion process more effectively. This study can provide reference for selecting Triticeae crops feeding in the future. To be more precise, bound phenol content in the insoluble dietary fiber of barley was the highest before digestion. The bound phenol in the insoluble dietary fiber of triticale had the best hypoglycemic ability. The bound phenolic compounds are mainly released during intestinal digestion, and their physiological functions are better than that in gastric digestion.

Secure consensus of multi-agent systems with redundant signal and communication interference via distributed dynamic event-triggered control.

This paper studies a class of multi-agent systems (MASs) subject to deception signal and communication interference. The objective of the present work is to establish a flexible and generalized distributed dynamic event-triggered control (DDETC) with impulsive signal to make the investigated MASs achieve secure consensus under redundant signal and communication interference. It is shown that Zeno behavior can be precluded with such a DDETC. The challenging but valuable new designed DDETC scheme shows the trigger is developed to achieve itself away from exceeding the data transmission load through parameter adjustment, to reduce redundant triggering, to flexibly adjust the triggered frequency, and even to replace sampled-data scheme as special cases. By the impulsive DDETC, anti-deception and anti-interference techniques, the secure consensus criteria of MASs are constructed cleverly. Numerical examples with simulations are given to illustrate the effectiveness of the proposed scheme and control protocol.

Clinical Decision Support for High-Risk Stage II Colon Cancer: A Real-World Study of Treatment Concordance and Survival.

BACKGROUND: Prognostic and pathologic risk factors typically guide clinicians and patients in their choice of surveillance or adjuvant chemotherapy when managing high-risk stage II colon cancer. However, variations in treatment and outcomes in patients with stage II colon cancer remain. OBJECTIVE: This study aimed to assess the survival benefits of treatments concordant with suggested therapeutic options from Watson for Oncology, a clinical decision support system. DESIGN: This is a retrospective observational study of concordance between actual treatment and Watson for Oncology therapeutic options. SETTING: This study was conducted at a top-tier cancer center in China. PATIENTS: Postoperative treatment data were retrieved from the electronic health records of 306 patients with high-risk stage II colon adenocarcinoma. MAIN OUTCOME MEASURES: The primary outcomes measured were the treatment patterns plus 3- and 5-year overall and disease-free survival for concordant and nonconcordant cases. RESULTS: Overall concordance was 90%. Most nonconcordant care resulted from adjuvant chemotherapy use (rather than surveillance) in patients with high-level microsatellite instability and ≥70 years old. No difference in overall survival (p = 0.56) or disease-free survival (p = 0.19) was observed between concordance groups. Patients receiving adjuvant chemotherapy had significantly higher 5-year overall survival than those undergoing surveillance (94% vs 84%, p = 0.01). LIMITATIONS: This study was limited by the use of retrospective cases drawn from patients presenting for surgery, the lack of complete follow-up data for 58% of patients who could not be included in the analysis, and a survival analysis that assumes no unmeasured correlation between survival and censoring. CONCLUSIONS: Watson for Oncology produced therapeutic options highly concordant with human decisions at a top-tier cancer center in China. Treatment patterns suggest that Watson for Oncology may be able to guide clinicians to minimize overtreatment of patients with high-risk stage II colon cancer with chemotherapy. Survival analyses suggest the need for further investigation to specifically assess the association between surveillance, single-agent and multiagent chemotherapy, and survival outcomes in this population. See Video Abstract at http://links.lww.com/DCR/B291. APOYO A LA DECISIÓN CLÍNICA DEL CÁNCER DE COLON EN ESTADIO II DE ALTO RIESGO: UN ESTUDIO DEL MUNDO REAL SOBRE LA CONCORDANCIA DEL TRATAMIENTO Y LA SUPERVIVENCIA: Los factores de riesgo pronósticos y patológicos generalmente guían a los médicos y pacientes en su elección de vigilancia o quimioterapia adyuvante cuando se trata el cáncer de colon en estadio II de alto riesgo. Sin embargo, las variaciones en el tratamiento y los resultados en pacientes con cáncer de colon en estadio II permanecen.Evaluar los beneficios de supervivencia de los tratamientos concordantes con las opciones terapéuticas sugeridas por "Watson for Oncology" (Watson para la oncología), un sistema de apoyo a la decisión clínica.Estudio observacional retrospectivo de concordancia entre el tratamiento real y las opciones terapéuticas de Watson para oncología.Un centro oncológico de primer nivel en China.Datos de tratamiento postoperatorio de registros de salud electrónicos de 306 pacientes con adenocarcinoma de colon en estadio II de alto riesgo.Patrones de tratamiento más supervivencia global y libre de enfermedad a 3 y 5 años para casos concordantes y no concordantes.La concordancia general fue del 90%. La mayoría de la atención no concordante resultó del uso de quimioterapia adyuvante (en lugar de vigilancia) en pacientes de alto nivel con inestabilidad de microsatélites y pacientes ≥70 años. No se observaron diferencias en la supervivencia global (p = 0,56) o la supervivencia libre de enfermedad (p = 0,19) entre los grupos de concordancia. Los pacientes que recibieron quimioterapia adyuvante tuvieron una supervivencia global a los 5 años significativamente más alta que los que fueron sometidos a vigilancia (94% frente a 84%, p = 0,01).Uso de casos retrospectivos extraídos de pacientes que se presentan para cirugía, falta de datos de seguimiento completos para el 58% de los pacientes que no pudieron ser incluidos en el análisis, y análisis de supervivencia que asume que no exite una correlación no medida entre supervivencia y censura.Watson para Oncología produjo opciones terapéuticas altamente concordantes con las decisiones humanas en un centro oncológico de primer nivel en China. Los patrones de tratamiento sugieren que Watson para Oncología puede guiar a los médicos para minimizar el sobretratamiento de pacientes con cáncer de colon en estadio II de alto riesgo con quimioterapia. Los análisis de supervivencia sugieren la necesidad de realizar mas investigaciónes para evaluar específicamente la asociación entre la vigilancia, la quimioterapia con uno solo o múltiples agentes y los resultados de supervivencia en esta población. Consulte Video Resumen en http://links.lww.com/DCR/B291. (Traducción-Dr. Gonzalo Hagerman).

Release characteristics of potassium and chlorine for torrefied wheat straw during a combined pyrolysis-combustion system.

The objective is to investigate the release characteristics of potassium (K) and chlorine (Cl) for torrefied wheat straw during a combined pyrolysis-combustion system. Powder and flake wheat straw samples were torrefied at different temperature of 200-300 ℃. The basic characteristics of torrefied samples and the K and Cl release rates of torrefied samples and their char samples derived from pyrolysis at 400-800 ℃ were analyzed and characterized. The results indicated that release rate of Cl was significantly higher than that of K under the same torrefaction conditions. In order to keep most of K and Cl remaining in biochar as well as the volatiles were completely released, the pyrolysis temperature of 700 ℃ for pyrolysis-combustion system was suitable. The total release rate of K and Cl at the pyrolysis temperature of 700 ℃ both exhibited a change trend of decreasing first and then increasing with the increase of torrefaction severity.

Strong Second Harmonic Generation in a Tungsten Bronze Oxide by Enhancing Local Structural Distortion.

To discover the nonlinear optical (NLO) materials with strong second harmonic generation (SHG), the design of NLO-active molecular units with large polarization is considered as a common strategy. Herein, we propose that the local structural distortion induced with vacancies, apart from the NLO-active units, can be employed to improve the NLO effect in solids as well. Accordingly, a new tungsten bronze (TB) oxide, Pb2(Pb0.15Li0.7□0.15)Nb5O15 (□ representing vacancies), is successfully designed and prepared, which exhibits a strong SHG response of 39 times that of KH2PO4. The detailed analysis reveals that the local structural distortions enhanced by the vacancies in PLN strengthen the local dipole moments of neighboring NbO6 octahedra, and thus significantly prompt the SHG effect. Moreover, a series of new TB compounds with large NLO effects are discovered by this molecular design strategy, which are perspectives for new NLO materials synthesis.

Manipulating Spin Alignments of (Y,Lu)1.7Fe17 Intermetallic Compounds via Unusual Thermal Pressure.

External pressure has been successfully employed to achieve desirable spin alignments in the field of materials science but is seriously restricted by the difficulty of reaching high pressure with conventional methods. The search for simple and effective ways to apply pressure on the lattice is challenging but intriguing. Here we report a new strategy to manipulate the spin alignments of (Y,Lu)1.7Fe17 intermetallic compounds through unusual thermal pressure. The spin alignments of Fe initially lie parallel inside the basal plane and then turn spirally between adjacent layers with a zone axis along the c direction under higher Lu concentration. The synchrotron and neutron powder diffraction investigations clearly reveal that the direction of spin alignments is highly correlated to large lattice contraction induced by negative thermal expansion (NTE), an unusual thermal pressure, along the c direction. The critical lattice parameter c to form spiral spin alignments is determined unambiguously. This work presents a feasible way to adjust spin alignments through NTE, which might be conducive to the future design of particular spin alignments instead of physical pressure for functional magnetic materials.