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A phytochemical investigation on 90% methanol extract from the leaves of

Objective To study the value of the subjective visual vertical (SVV) in the diagnosis of vestibular migraine (VM). Methods This study recruited 128 VM patients and 64 age-matched normal subjects. We detected the SVV during the interval between attacks in both groups, in sitting upright, and the head tilted at 45° to the left or right. We then examined the correlation between the SVV results with the vestibular evoked myogenic potential (VEMP) and canal paresis (CP). Results It was found there was a significant difference in SVV at the upright position between VM patients and normal controls (P=0.006) and no significant difference was found at the tilts of 45° to the left or right between the two groups. The SVV results at the upright position were significantly correlated with cervical VEMP (P=0.042) whereas not significantly correlated with CP and VEMP. There existed no significant difference in the conformity to the Müller effect (M effect) between the two groups. ROC analysis exhibited that the sensitivity, specificity of SVVs at the upright were 67.200% and 62.500% respectively. The diagnostic value of SVV at the upright position was significantly higher than that at tilts of 45° to the left and right (P=0.006). Nonetheless the diagnostic accuracy was relatively low. Conclusion Abnormality in SVV possibly stems from the lasting functional disorder of cerebellar or high-level cortical centers in VM patients or is linked to the vestibular compensation. The SVV is of low diagnostic value for VM and the value of SVV in VM warrants further study.

Symmetries, due to their fundamental importance to dynamical processes on networks, have attracted a great deal of current research. Finding all symmetric nodes in large complex networks typically relies on automorphism groups from algebraic-group theory, which are solvable in quasipolynomial time. We articulate a conceptually appealing and computationally extremely efficient approach to finding and characterizing all symmetric nodes by introducing a structural position vector (SPV) for each node in networks. We establish the mathematical result that symmetric nodes must have the same SPV value and demonstrate, using six representative complex networks from the real world, that all symmetric nodes in these networks can be found in linear time. Furthermore, the SPVs not only characterize the similarity of nodes but also quantify the nodal influences in propagation dynamics. A caveat is that the proved mathematical result relating the SPV values to nodal symmetries is not sufficient; i.e., nodes having the same SPV values may not be symmetric, which arises in regular networks or networks with a dominant regular component. We point out with an analysis that this caveat is, in fact, shared by the known existing approaches to finding symmetric nodes in the literature. We further argue, with the aid of a mathematical analysis, that our SPV method is generally effective for finding the symmetric nodes in real-world networks that typically do not have a dominant regular component. Our SPV-based framework, therefore, provides a physically intuitive and computationally efficient way to uncover, understand, and exploit symmetric structures in complex networks arising from real-world applications.

Non-used clinical information has negative implications on healthcare quality. Clinicians pay priority attention to clinical information relevant to their specialties during routine clinical practices but may be insensitive or less concerned about information showing disease risks beyond their specialties, resulting in delayed and missed diagnoses or improper management. In this study, we introduced an electronic health record (EHR)-oriented knowledge graph system to efficiently utilize non-used information buried in EHRs. EHR data were transformed into a semantic patient-centralized information model under the ontology structure of a knowledge graph. The knowledge graph then creates an EHR data trajectory and performs reasoning through semantic rules to identify important clinical findings within EHR data. A graphical reasoning pathway illustrates the reasoning footage and explains the clinical significance for clinicians to better understand the neglected information. An application study was performed to evaluate unconsidered chronic kidney disease (CKD) reminding for non-nephrology clinicians to identify important neglected information. The study covered 71,679 patients in non-nephrology departments. The system identified 2,774 patients meeting CKD diagnosis criteria and 10,377 patients requiring high attention. A follow-up study of 5,439 patients showed that 82.1% of patients who met the diagnosis criteria and 61.4% of patients requiring high attention were confirmed to be CKD positive during follow-up research. The application demonstrated that the proposed approach is feasible and effective in clinical information utilization. Additionally, it's valuable as an explainable artificial intelligence to provide interpretable recommendations for specialist physicians to understand the importance of non-used data and make comprehensive decisions.

Modern diesel engines are struggling to enhance the power density. This is usually realized by being equipped with a turbocharger, which demands higher performances on exhaust flow and exhaust waste energy recovery (WER). In the present study, we investigated the variations of exhaust flow and exhaust energy recovery performance with different geometrical parameters of exhaust system and proposed an evaluation and optimal design method of the exhaust system for a turbocharging diesel engine with a module pulse converter (MPC) system. The macro engine performances and the micro flow fields in exhaust system are obtained from the one/three dimensional (1D-3D) coupling simulation, and the energy of exhaust gas is quantified and analyzed with a concept of air power. It can be concluded that with a view to the exhaust performance and exhaust energy utilization, the diameter of the exhaust pipe should be set equal to the outlet diameter of the manifold and there is an optimized value of the contraction rate of the exhaust manifold. Besides, a parameter of the exhaust system called power potential coefficient is proposed to qualitatively evaluate the exhaust performance and exhaust energy.

Hydraulic support plays a key role in ground control of longwall mining. The smart prediction methods of support load are important for achieving intelligent mining. In this paper, the hydraulic support load data is decomposed into trend term, cycle term, and residual term, and it is found that the data has clear trend and period features, which can be called time series data. Based on the autoregression theory and weighted moving average method, the time series model is built to analyze the load data and predict its evolution trend, and the prediction accuracy of the sliding window model, ARIMA (Autoregressive Integrated Moving Average) model, and SARIMA (Seasonal Autoregressive Integrated Moving Average) model to the hydraulic support load under different parameters are evaluated, respectively. The results of single-point and multipoint prediction test with various sliding window values indicate that the sliding window method has no advantage in predicting the trend of the support load. The ARIMA model shows a better short-term trend prediction than the sliding window model. To some extent, increasing the length of the autoregressive term can improve the long-term prediction accuracy of the model, but it also increases the sensitivity of the model to support load fluctuation, and it is still difficult to predict the load trend in one support cycle. The SARIMA model has better prediction results than the sliding window model and the ARIMA model, which reveals the load evolution trend accurately during the whole support cycle. However, there are many external factors affecting the support load, such as overburden properties, hydraulic support moving speed, and worker’s operation. The smarter model of SARIMA considering these factors should be developed to be more suitable in predicting the hydraulic support load.

Axially chiral biaryls are common structural motifs in functional materials, bioactive natural products, pharmaceuticals and chiral catalysts/ligands. As such, efficient preparation of these privileged scaffolds is an important endeavour in organic chemistry. Herein we report a general and modular platform technology for the construction of axial chirality via palladium/chiral norbornene cooperative catalysis. It is a three-component cascade process that involves widely available aryl iodides, 2,6-substituted aryl bromides and olefins (or alkynes, boronic acids and so on) as the reactants. A wide variety of substrates bearing an assortment of functional groups (88 examples) are compatible with this method. Other features include a distinct stereoinduction model, excellent enantioselectivities, step economy and scalability. This method is also amenable for the synthesis of chiral fluorenols through axial-to-central chirality transfer in high stereochemical fidelity. We anticipate that this work will have broad synthetic utilities in chiral ligands and catalyst-design for asymmetric catalysis. Axial chirality is found in many important compounds, such as bioactive molecules and catalytic components. Now palladium and chiral norbornene cooperative catalysis is reported for the construction of atropisomeric biaryls and chiral fluorenols.

Alpine meadows, comprising the main ecosystem of the Three-River Source Region, play an important role in the economic development of western pastoral areas. To determine whether the grazing level was too intense or the nutrient-carrying capacity of the meadows was overloaded, and to offer solutions in Maqin County, Qinghai Province, China, the meadows carrying capacity was determined by combining grass-yield and nutrients data for different seasons across different meadows. The results showed that the levels of crude protein (CP), ether extract (EE), ash, soluble sugars (SS), gas production, and energy value of forage in the summer–autumn grazing meadows were higher than those of the winter–spring meadows. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) of forage in the summer–autumn grazing meadows were lower than those of the winter–spring meadows. We found that no pastures were overloaded with metabolizable energy (ME) for the whole year but digestible crude protein (DCP) was overloaded in winter–spring. And there were differences in the amount carrying capacity (forage yield) of seasonal grazing meadows for the different herds, the overload types were annual overloading (herd A), overloaded in summer–autumn (herd B), overloaded in winter–spring (herd C), and not overloaded (herd D). Compared with the previous grazing mode, theoretical carrying capacity, DCP carrying capacity, and ME carrying capacity of herd A increased by 20, 19, and 27 sheep units, respectively, after optimization; herd B: 36, 31, and 45 sheep units, respectively; herd C: 28, 23, and 44 sheep units, respectively; and herd D: 43, 40, and 61 sheep units, respectively. In the Three-River Source Region and similar alpine pastoral areas, the grassland-livestock structure should be optimized to improve grassland vegetation status and increase the theoretical carrying capacity.

The influence of blades assembly, i.e., the blade number on the solidification process, heat exchange and grain structure on a directionally solidified Ni-based superalloy DZ125 was investigated by combining the experimental and simulation results. The casting process was simulated thermodynamically by ProCAST software, where the interface heat transfer coefficient was precisely determined by a measurement with thermocouples. There is a good agreement between experimental and simulation results. It was interestingly found that with the number of blades increasing from 6 to 10, due to the decrease in radiation absorption efficiency, the maximum temperature and the heating rate decrease in the mold, during the preheat process. During the withdrawal procedure, increased assembly numbers reduce the radiation exchange from mold to the enclosure, resulting in the decrease in cooling rate and temperature gradient of the blades. At the end of withdrawal, the slower cooling rate of the outside balances the temperature distribution of internal and external surfaces on the rabbet of blade. The interface heat transfer coefficient (IHTC) values of DZ125 casting system were investigated by inverse method. Then, a series of assembly blade groups were designed and being cast and calculated. Values of IHTC are proved to be suitable for different assembly groups of casting in this case. Based on simulation and experimental results, it was interestingly found that: In the preheating process, with the number of blades increased, the maximum temperature on the mold becomes lower and the heating rate becomes slower, which result from the decrease in radiation efficiency between the mold and graphite heater. During the withdrawal, increasing assembly blade number reduced the radiation exchange from the mold to the enclosure, and it results in the cooling rate and temperature gradient on the blades getting decreased. At the end of withdrawal, the slower cooling rate leads to the temperature distribution maintaining uniformity for internal and external surfaces on the rabbet of the blade.

In the field of low temperature co-fired ceramic (LTCC), it remains a challenge to design the performance of LTCC with low permittivity less than 5. Here, the K2O– B2O3–SiO2–Al2O3 composites are prepared without the preparation of prior glass. Meanwhile, the factors of the CaO content on microstructure, phase structure and properties of the composites are considered systematically. The crystal structure measured by X-ray diffraction (XRD) shows that there are quartz and alumina as the crystal phases. The results reveals that the tailoring CaO content benefits sintering densification, low dielectric loss, great mechanical properties and low thermal expansion coefficient. As CaO content increases up to 2.8 wt%, the composites sintered at 850∘C have a dielectric constant of 4.94 and tanδ of 8 × 10−4 at 1 MHz, thermal expansion coefficient (CTE) of 8.5 ppm/∘C, and flexural strength of 150 MPa. As the mass fraction of CaO increases up to 3.2 wt%, the maximum flexural strength of 173MPa is achieved. The above study provides an effective approach for preparing the novel composites as a promising candidate for LTCC applications.

Synchronous measurement of full-field temperature and deformation at high temperature especially more than 1273 K is of much significance especially for part applications of turbine structures and materials. Non-contact optical methods attract more and more attention, however, current methods all face different challenges, such as strong light reflection on the surface of the specimen, disturbing radiation from environment, complex equipment setup, limited measured temperature not higher than 900 ℃ and so on. In this work, we develop an innovative technique to overcome some current problems. The measurement system employing an ultraviolet (UV) imaging system is composed of a scientific complementary metal oxide semiconductor (sCMOS) camera, a lens and a UV bandpass filter. The UV bandpass filter was used for thermal radiation elimination to acquire high quality images at elevated temperatures for deformation field calculation suitable for digital image correlation (DIC) method. The UV sensitive sCMOS camera without using active illumination was employed to collect enough UV radiation energy and eliminate the interference of the external ambient light, which is applicable for high accuracy temperature field measurement. Our system can realize the synchronous capture of image and temperature acquisition with passive UV imaging system at temperature not lower than 1473K. The feasibility of the method was verified through heating molybdenum (Mo) and Ni-based superalloy IC21 materials. The temperature fields of Mo measured by the established imaging system up to 1835 K with error less than 0.25% showed the effectiveness for temperature measurement. The estimated deformation and temperature field of Ni-based superalloy IC21 up to 1473 K with measured temperature error less than 0.5% demonstrated well the great potential of the UV imaging system in simultaneous measurement of temperature and deformation fields at elevated temperatures.

Herein we report an asymmetric two-component vinylogous Catellani reaction for the construction of C-N axial chirality through a palladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer process. Various partially aromatic iodinated 2-pyridones, quinolones, coumarin and uracil substrates react with 2,6-disubstituted aryl bromides with a tethered amide group, to afford a wide variety of polycyclic C-N atropisomers (39 examples, up to 97% ee ). The obtained C-N axial chirality is originated from the preformed transient C-C axial chirality with high fidelity. The synthetic utility of this chemistry is demonstrated by facile preparation of complex quinoline and pyridine based C-N atropisomers through a N -deprotection and aromatization sequence. In addition, a remote axial-to-central diastereoinduction process dictated by C-N axial chirality is observed with excellent diastereocontrol. This research opens a new avenue for asymmetric synthesis.

Heterocycles 2-pyridone and uracil are privileged pharmacophores. Diversity-oriented synthesis of their derivatives is in urgent need in medicinal chemistry. Herein, we report a palladium/norbornene cooperative catalysis enabled dual-functionalization of iodinated 2-pyridones and uracils. The success of this research depends on the use of two unique norbornene derivatives as the mediator. Readily available alkyl halides/tosylates and aryl bromides are utilized as ortho-alkylating and -arylating reagents, respectively. Widely accessible ipso-terminating reagents, including H/DCO2Na, boronic acid/ester, terminal alkene and alkyne are compatible with this protocol. Thus, a large number of valuable 2-pyridone derivatives, including deuterium/CD3-labeled 2-pyridones, bicyclic 2-pyridones, 2-pyridone-fenofibrate conjugate, axially chiral 2-pyridone (97% ee), as well as uracil and thymine derivatives, can be quickly prepared in a predictable manner (79 examples reported), which will be very useful in new drug discovery., Diversity-oriented synthesis of 2-pyridone and uracil derivatives is in urgent need in medicinal chemistry as they are useful pharmacophores. Here the authors show that palladium/norbornene cooperative catalysis enabled dual-functionalization of iodinated 2- pyridones and uracils.

Reported is a modular strategy for the preparation of the unique benzofused dioxabicycle scaffolds involving a Catellani reaction of aryl iodides, epoxides, and terminal alkynes and an oxa-cyclizat...

In the field of low temperature co-fired ceramic (LTCC), it remains a challenge to design the performance of LTCC with low permittivity less than 5. Here, a novel glass mixture of K-Al-B-Si-O (KABS) and Zn-B-Si-O (ZBS) is introduced as a sintering aid of alumina to obtain ultralow-permittivity glass/Al2O3 composite. Meanwhile, the factors of glass mixture component on microstructure, phase structure and dielectric properties of the composites are considered systematically. The crystal structure measured by X-ray diffraction (XRD) shows that pure crystalline phase of ZnAl2O4 spinel can be attained by tailoring the component of the glass mixture. In case of mass ratio of KABS: ZBS equal to 6:4, it favors to efficiently increase the sintering densification of composite, and significantly benefit the low dielectric loss, good mechanical and thermal performances. In detail, the optimal glass/ceramic composites sintered at 850 °C for 2 h exhibit the bulk density of 2.89 g/cm3, er of 4.92 at 14 GHz and Q × f of 6873 GHZ, flexural strength of 202 MPa, thermal expansion coefficient of 5.5 ppm/°C. The above study provides an effective approach for preparing the novel composites as a promising candidate for LTCC applications.

The high temperature tensile behavior for film-hole plates of a Ni based single-crystal superalloy has been investigated. Both the hole and the drill-produced recast layer are detrimental to tensile properties. During yielding, the strain distribution obtained in-situ by digital image correlation technique exhibits an X-like concentration at directions around the hole. The crack initiates on the hole's edge with different crystallographic directions, depending on the recast layer. The fracture mechanism for 980 °C tensile exhibits a necking-dimple process, where plastic deformation is originated from the a/2 [ 101 ] ( 1 1 ¯ 1 ¯ ) dislocation's by-passing. The Peierls-Nabarro force on [ 101 ] ( 1 1 ¯ 1 ¯ ) slip system is 258.7 MPa, leading to the yielding of plate-type specimen. The finite-element method results indicate an X-like concentration of the resolved shear stress for such slip system around the hole, where the stress exceeds the Peierls-Nabarro force. This results in an X-like plastic deformation during yield, which explains the in-situ experimental results. The different chemical compositions and phase structures result in the softer nature of recast layer and the special stress/strain concentrated in it. The crack initiation and propagation around the hole also investigated in detail, via combining the experimental and computational results.

The increased demand for high-speed, high-precision, stable, and long-life machine tools has made high-precision spindles an important topic of research. The key component of the machine tool spindle that supports the shaft is the ball bearing, whose characteristics are closely related to the spindle preload. In this study, a spindle preload control mechanism is designed using a piezoelectric actuator and a beveled spacer ring. Mechanical effects of the spindle preload are analyzed and controlled, and an experimental full-sized model is fabricated and tested. Results show that increased preload reduces vibration amplitude and raises the bearing temperature. All the measured mechanical effects are positively correlated with the controlled spindle preload.

Objective To explore the change of serum sex hormones and 25-hydroxycholecalciferol [25-(OH)-D3 ] level in postmenopausal female patients with benign paroxysmal positional vertigo (BPPV). Methods Electrochemiluminescence (ECL) assay was employed to detect the serum levels of estradiol (E2), progesterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), and 25-(OH)-D3 in 63 female postmenopausal BPPV patients with age 50-80 years from September 1, 2015 to February 1, 2017. Spearman rank correlation analysis was used to analyze the relation between age and E2 , E2 and 25-(OH)-D3. Univariate and multivariate stepwise Logistic regression analysis were used to screen the risk factors for BPPV. Results The serum levels of E2 [15.67 (10.96, 22.15) pg/ml] and 25-(OH)-D3 [(24.24 ± 1.05) ng/ml] in BPPV group were lower than those in control group [E2: 31.78 (25.60, 39.50) pg/ml, 25-(OH)-D3: (27.62 ± 0.76) ng/ml], and the differences were statistically significant (Z = -6.768, P = 0.000; t = -2.605, P = 0.010). There was no significant difference on progesterone, LH and FSH between 2 groups. Correlation analysis showed there was no relation between E2 and 25-(OH)-D3 levels in both groups. There was a negative correlation between age and E2 in control group (rs = -0.263, P = 0.038), but no correlation in BPPV group. Multivariate Logistic regression analysis showed decreased serum E2 and 25-(OH)-D3 levels maybe the risk factors for postmenopausal female BPPV patients. Conclusions E2 and 25-(OH)-D3 deficiency are independent risk factors for BPPV in postmenopausal female patients. DOI: 10.3969/j.issn.1672-6731.2019.01.007

OBJECTIVE To compare the performances among three different systems for video head impulse test (vHIT), and to identify an optimal target angle for precisely evaluating the function of vertical semicircular canals in vHIT. METHODS A two-center prospective study was done. Participants were sit 1.2 m away from the wall in a noise-proved room that dedicated for vHIT experiments. During the comparison experiments, similar settings were ensured in both hospitals, with the same distance to wall and angle of staring. For each equipment, the procedures followed the developers' recommendations. The same examiner performed the comparison between two systems in one location. For the eye-position projects, targets were placed on the wall sequentially at the pre-marked lines for different angles. For the comparison projects, 9 and 13 participants were recruited, respectively. Any participant with otologic or vestibular disorders was excluded. A total of 26 healthy participants were recruited in the eye-position experiments, 16 of which were further involved in inter-examiner tests. RESULTS Our evaluations of three different systems showed that a new vHIT system, VertiGoggles® ZT-VNG-I (VG) performed as good as the long-tested Otometrics® ICS impulse (Oto) and EyeSeeCam® (ESC). During the comparison, we validated 25-degree, instead of right ahead at 0 degree, is a better place to set the targets when torsion was applied at vertical semicircular canal planes. CONCLUSION The new VG system is good for clinical practices. Furthermore, we proposed a new protocol to set the targets 25 degrees from right ahead after tilting head 45 degrees to evaluate vertical canals during vHIT.

In the background of ultra-dense network (UDN), with the increasingly densification of network structure, the distance between base stations becomes closer, and one user may be in the service range of multiple small base stations, thus forming a user-centered virtual cell system. In this system, with more and more unlimited devices accessed to the network, spectrum resources are becoming more and more tense. Compared with orthogonal multiple access (OMA), non-orthogonal multiple access (NOMA) can make better use of spectrum resources to meet the access requests of more access devices. In recent years, more and more attentions are drawn to information security issues, so it is important to use physical layer security (PLS) technology to ensure the safe access of users in the presence of eavesdropping nodes. This paper discusses the user access issue in UDN considering PLS and NOMA, and proposes a non-cooperative game theory method to maximize sum of the User’s communication rate in the system through multi-round dynamic games. Through simulation analysis, we proved the effectiveness of our proposed method.

According to the official report, the first case of COVID-19 and the first death in the United States occurred on January 20 and February 29, 2020, respectively On April 21, California reported that the first death in the state occurred on February 6, implying that community spreading of COVID-19 might have started earlier than previously thought Exactly what is time zero, i e , when did COVID-19 emerge and begin to spread in the U S and other countries? We develop a comprehensive predictive modeling framework to address this question Using available data of confirmed infections to obtain the optimal values of the key parameters, we validate the model and demonstrate its predictive power We then carry out an inverse inference analysis to determine time zero for 10 representative states in the U S , plus New York City, United Kingdom, Italy, and Spain The main finding is that, in both the U S and Europe, COVID-19 started around the new year day

We uncover a phenomenon in coupled nonlinear networks with a symmetry: as a bifurcation parameter changes through a critical value, synchronization among a subset of nodes can deteriorate abruptly, and, simultaneously, perfect synchronization emerges suddenly among a different subset of nodes that are not directly connected. This is a synchronization metamorphosis leading to an explosive transition to remote synchronization. The finding demonstrates that an explosive onset of synchrony and remote synchronization, two phenomena that have been studied separately, can arise in the same system due to symmetry, providing another proof that the interplay between nonlinear dynamics and symmetry can lead to a surprising phenomenon in physical systems.