Quantum spin liquid signatures in monolayer 1T-NbSe2

Quantum spin liquids (QSLs) are in a quantum disordered state that is highly entangled and has fractional excitations. As a highly sought-after state of matter, QSLs were predicted to host spinon excitations and to arise in frustrated spin systems with large quantum fluctuations. Here we report on the experimental observation and theoretical modeling of QSL signatures in monolayer 1T-NbSe2, which is a newly emerging two-dimensional material that exhibits both charge-density-wave (CDW) and correlated insulating behaviors. By using scanning tunneling microscopy and spectroscopy (STM/STS), we confirm the presence of spin fluctuations in monolayer 1T-NbSe2 by observing the Kondo resonance as monolayer 1T-NbSe2 interacts with metallic monolayer 1H-NbSe2. Subsequent STM/STS imaging of monolayer 1T-NbSe2 at the Hubbard band energy further reveals a long-wavelength charge modulation, in agreement with the spinon modulation expected for QSLs. By depositing manganese-phthalocyanine (MnPc) molecules with spin S = 3/2 onto monolayer 1T-NbSe2, new STS resonance peaks emerge at the Hubbard band edges of monolayer 1T-NbSe2. This observation is consistent with the spinon Kondo effect induced by a S = 3/2 magnetic impurity embedded in a QSL. Taken together, these experimental observations indicate that monolayer 1T-NbSe2 is a new promising QSL material.

[Response characteristics of tislelizumab combined with chemotherapy in first-line treatment of locally advanced or metastatic non-squamous non-small cell lung cancer]

Objective: To investigate the response characteristics of patients with locally advanced/metastatic non-squamous non-small cell lung cancer (nsq-NSCLC) treated with tislelizumab in combination with chemotherapy in the first line. Methods: Patients with nsq-NSCLC who achieved complete or partial remission after treatment with tislelizumab in combination with chemotherapy or chemotherapy alone in the RATIONALE 304 study, as assessed by an independent review board, were selected to analyze the response characteristics and safety profile of the responders. Time to response (TTR) was defined as the time from randomization to the achievement of first objective response. Depth of response (DpR) was defined as the maximum percentage of tumor shrinkage compared with the sum of the baseline target lesion length diameters. Results: As of January 23, 2020, 128 patients treated with tislelizumab in combination with chemotherapy achieved objective tumor response (responders), representing 57.4%(128/223) of the intention-to-treat population, with a TTR of 5.1 to 33.3 weeks and a median TTR of 7.9 weeks. Of the responders (128), 50.8%(65) achieved first remission at the first efficacy assessment (week 6), 31.3%(40) at the second efficacy assessment (week 12), and 18.0%(23) at the third and subsequent tumor assessments. The percentages of responders who achieved a depth of tumor response of 30% to <50%, 50% to <70% and 70% to 100% were 45.3%(58/128), 28.1%(36/128) and 26.6%(34/128), respectively, with median progression-free survival (PFS) of 9.0 months (95% CI: 7.7 to 9.9 months), 11.5 months (95% CI: 7.7 months to not reached) and not reached (95% CI: 11.8 months to not estimable), respectively. Tislelizumab plus chemotherapy were generally well tolerated in responders with similar safety profile to the overall safety population. Conclusion: Among responders to tislelizumab in combination with chemotherapy for nsq-NSCLC, 82.0%(105/128) achieves response within the first two tumor assessments (12 weeks) and 18.0%(23/128) achieves response at later (18 to 33 weeks) assessments, and there is a trend toward prolonged PFS in responders with deeper tumor response.

[Development of Risk Assessment Index System on HIV infection among young students based on Delphi method]

Objective: To develop a Risk Assessment Index System (RAIS) on HIV infection among young students based on Delphi method and to provide individual HIV infection risk assessment, targeted prevention and control measures. Methods: Delphi method was applied to determine the index system and weight of the assessment tool through three rounds of expert consultation and overall consideration of opinions and suggestions from 19 experts. Results: The positivity coefficients of three rounds of expert consultation were 100%. The authority coefficient of experts was between 0.887 and 0.945. The Kendall's W coefficients through first, second and third round specialist consultation was 0.379, 0.329 and 0.248, respectively (all P<0.001). The coefficients of variation in the third round were all less than 0.25, indicating that experts' opinion tend to be consistent and the results are highly reliable. The HIV infection risk assessment index system among young students consisted of 7 first grade indices and 54 second grade indices, of which weight was calculated. Conclusions: The RAIS on HIV infection for young students was initially established based on Delphi method, and could be used in the development of HIV infection risk assessment tools for personalized prevention and intervention among young students. However, the reliability, validity and effect of this assessment index system need to be further evaluated.

[Design and analysis of testing results of a WeChat applet for sexual health and HIV infection risk assessment in young students]

Objective: To summarize the design and analysis of testing results of a WeChat applet, which is called "Detective Bear", for sexual health and HIV infection risk assessment in young students, and evaluate its feasibility and effectiveness. Methods: Based on self-categorization theory, by using cluster analysis and Delphi expert consulting method, the framework of WeChat applet, risk assessment index system and preventive intervention content were determined. Young students were recruited by student associations for the application test, the results of the repeated tests and the satisfaction survey were collected and analyzed. Results: The study included 393 participants who repeated the test twice and 750 participants who volunteered to participate in the satisfaction questionnaire survey. The applet contains five modules: self-role judgment, self-test, risk assessment, assessment report generation and background management. The risk assessment module contains 6 first-level indicators and 55 second-level indicators. Assessment report generation module includes role diagnosis type, radar chart of HIV sexual health KAP and intervention prescription. In 393 students who repeated the test, the awareness of AIDS to be a serious sexually transmitted disease, the epidemic trend in young students in China, with active seeking HIV testing services and caring the infected improved. The satisfaction survey showed that 75.7% of students (568/750) accepted the applet, 86.5% (649/750) agreed the evaluation report, 83.1%(623/750) thought that there were some problems, but it was easy to use, 93.3% (700/750) said they can learn something from the applet and 84.1% (631/750) satisfied with the page design. Some students thought the questionnaire was too long and somewhat difficult to complete (P<0.05), and some reported that more can be learned (P<0.05). Conclusions: The applet integrates AIDS prevention related knowledge and practice into a challenging, interesting, interactive game and provide individualized, concrete risk assessment and self-intervention for young students, which can effectively help students to improve the awareness of AIDS related knowledge and get links for access to condoms, testing and other intervention services. However, its large-scale application and long-term effect need to be further tested.

[Influence of self-categorized deviation in knowledge, attitude and practice for sexual health on the willingness to seek help for corresponding problems among young students]

Objective: To evaluate the effect of "self-categorization" on decision of health preference and the influence of self-categorized deviation in knowledge, attitude and practice (KAP) on the willingness of seeking help for sexual health among young students. Methods: From March to April 2019, young students who used a WeChat applet for sexual health and HIV infection risk assessment, which is called "Detective Bear" were recruited and investigated. According to the consistency between the self-categorization of KAP for sexual health and the systematic categorization from their honest answers, the participants were allocated into three groups: consistent, low or high status, according to their judgment on sexual information acquisition, sexual attitude, and the actual number of sexual experiences. Logistic regression was used to analyze the differences in the willingness to seek help for sexual health problems between the three groups. Results: 2 009 students with an average age of (19.2±1.1) were included. 54.7% (1 099/2 009) were female, and 98.4% (1 976/2 009) were college, undergraduate or postgraduate students. 49.0% (984/2 009) were in the consistent group, 10.9% (219/2 009) had a lower self-categorization, 40.1% (806/2 009) had a higher self-categorization. Compared with the consistent group, students with lower self-categorization of KAP for sexual health were less likely to assess HIV voluntary counseling and testing (aOR=0.65, 95%CI: 0.43-0.99). However, students with higher self-categorization seemed to dislike seeking help for sexually transmitted diseases (aOR=0.76, 95%CI: 0.59-0.98). Conclusions: Deviation in self-categorization of KAP for sexual health will reduce the young students' willingness to seek help for related problems. Especially those with lower self-categorization, lack of risk consciousness, and refuse to assess counseling and testing may increase the HIV/AIDS epidemic among this population. It is necessary to strengthen the capacity of self-assessment for young students while promoting sex education.

[Analysis on influencing factors of HIV testing services utilization in students with self-assessed high risk of HIV infection based on Andersen's model]

Objective: To analyze the influencing factors for HIV testing services utilization in students with self-assessed high risk of HIV infection. Methods: The research framework of the influencing factors for HIV testing services utilization in students was developed based on Andersen's health services utilization behavioral model and related literature. A cross-sectional survey was performed in students with self-assessed high risk of HIV infection by an online HIV infection risk assessment tool from March to April 2019. Multiple logistic regressions were applied with hierarchical model. Results: A total of 526 students were included in the study (age: 19.30±1.19 years old), in whom 96.2% agreed that HIV testing should be received after high-risk behavior. 56.7% (298/526) had sexual behavior and the HIV testing rate was 11.0% (58/526). The HIV testing rates in students who had and had no sex behavior were 13.42%(40/298) and 7.89% (18/228), respectively. According to the results from multivariate logistic regression analysis, non-heterosexual (compared with heterosexual, OR=7.88, 95%CI: 3.98-15.61) and higher score of AIDS knowledge awareness (compared with lower score, OR=2.05, 95%CI: 1.07-3.93) in propensity factor module, and having risk sexual behavior (compared with having no risk sexual behavior, OR=2.66, 95%CI: 1.41-5.03) and having diagnosis of STD infection in hospital (compared with having no such diagnosis, OR=6.35, 95%CI: 2.21-18.27) in demand factor module, and receiving health education about AIDS prevention in the past year (compared with receiving no such health education, OR=0.29, 95%CI: 0.11-0.76) and receiving health education about AIDS testing service in the past year (compared with receiving no such health education, OR=3.67, 95%CI: 1.71-7.90) in ability factor module were the influencing factors for utilization of HIV testing services. Conclusions: The acceptance of HIV testing in students needs to be improved urgently. Propensity factors, such as their AIDS knowledge awareness and sexual orientation, and demand factors, such as having risk sexual behavior and STD infection, have obvious impacts on the utilization of HIV testing services. However, health education about AIDS prevention and HIV testing service can play a more important role in facilitating the utilization of HIV testing in students. In the future, we should further strengthen the publicity of voluntary HIV counseling and testing service in students with particular attention to girls and those with risk sexual behaviors.

[Cluster analysis on survey of sexual health characteristics and health education demands in young students]

Objective: To explore the difference of sexual health characteristics and demands in students in different groups, and provide the basis for targeted sexual health eduction for AIDS prevention in young students. Methods: A survey was conducted based on the requirement of health education about sexual health and AIDS prevention in young students by the education department of Guangdong province. A two-step cluster analysis was performed on the survey data obtained by convenient sampling, the variables and number of clusters included were determined by combination of analysis results and professional knowledge. The demographic characteristics, the content and form of sexual health education needed were compared among different groups. Results: Survey data of 3 884 students were collected, and six variables were used for classification: cognition or occurrence masturbation, sexual behavior, frequency of sexual information acquisition, number of acceptable sex partners and AIDS knowledge awareness rate. By these variables, the students were classified into three levels of risk groups: high risk group (46.6%), medium risk group (39.9%) and low risk group (13.5%). As for demographic characteristics, high risk group, with a median age of 19 years, had the highest proportions of boys (65.9%), students with non-heterosexuality orientation (15.2%), urban residents (58.2%), only children (30.8%) and undergraduates (54.7%). Medium risk group, with a median age of 19 years, had the highest proportions of girls (82.7%) and vocational college students (34.0%). Low risk group, with a median age of 18 years, had the highest proportions of rural residents (52.4%), non-only child (80.6%), senior high school students (41.3%), non-boarding students (17.5%) and students without internship and part-time job experience (43.2%). In terms of health education demands, high risk group had a higher demand of information about self-identity, sexual safety, sexual decision making, contraception, abortion, and sexually transmitted disease or AIDS prevention. Medium risk group paid more attention to value on love and marriage, sexual assault. Low risk group showed a higher demand of adolescent physiology knowledge. Compared with low risk group, high risk group had a higher demand of peer education, Internet/multimedia, anonymous counseling and other forms of sexual health education. The differences were significant. Conclusion: The characteristics, sexual knowledge awareness, attitude and behavior, and health education demands of young students in different groups are different, so health education materials and methods should be developed according to the characteristics of different groups to enhance the acceptance and enthusiasm of students and improve the quality of sexual health education.

Giant orbital magnetoelectric effect and current-induced magnetization switching in twisted bilayer graphene

Recently, quantum anomalous Hall effect with spontaneous ferromagnetism was observed in twisted bilayer graphenes (TBG) near 3/4 filling. Importantly, it was observed that an extremely small current can switch the direction of the magnetization. This offers the prospect of realizing low energy dissipation magnetic memories. However, the mechanism of the current-driven magnetization switching is poorly understood as the charge currents in graphenes are generally believed to be non-magnetic. In this work, we demonstrate that in TBG, the twisting and substrate induced symmetry breaking allow an out of plane orbital magnetization to be generated by a charge current. Moreover, the large Berry curvatures of the flat bands give the Bloch electrons large orbital magnetic moments so that a small current can generate a large orbital magnetization. We further demonstrate how the charge current can switch the magnetization of the ferromagnetic TBG near 3/4 filling as observed in the experiments.

The mechanism of current-driven magnetization switching in twisted bilayer graphene (TBG) is poorly understood. Here, He et al. show that a small current can generate a large orbital magnetization due to symmetry breaking by the twisting and substrate in TBG, leading to a giant orbital magnetoelectric effect.

Grouting Quality Evaluation in Post-Tensioning Tendon Ducts Using Wavelet Packet Transform and Bayes Classifier

The grouting quality of tendon ducts is very important for post-tensioning technology in order to protect the prestressing reinforcement from environmental corrosion and to make a smooth stress distribution. Unfortunately, various grouting defects occur in practice, and there is no efficient method to evaluate grouting compactness yet. In this study, a method based on wavelet packet transform (WPT) and Bayes classifier was proposed to evaluate grouting conditions using stress waves generated and received by piezoelectric transducers. Six typical grouting conditions with both partial grouting and cavity defects of different dimensions were experimentally investigated. The WPT was applied to explore the energy of received stress waves at multi-scales. After that, the Bayes classifier was employed to identify the grouting conditions, by taking the traditionally used total energy and the proposed energy vector of WPT components as input, respectively. The experimental results demonstrated that the Bayes classifier input with the energy vector could identify different grouting conditions more accurately. The proposed method has the potential to be applied at key spots of post-tensioning tendon ducts in practice.

[Characteristic analysis among MSM-users of the "Online HIV Acquisition Risk Assessment System" in Guangzhou]

Objective: To analyze the characteristics of levels related to the risk through self-evaluation system, among MSM users in Guangzhou, between 2015 and 2017. Methods: Between 2015 and 2017, data was collected from the users of a self-evaluation system network related to HIV infection, based on the previous 'HIV health risk appraisal model'. Information on risk factors was collected to calculate the scores and levels of risks and to estimate the incidence of HIV. Taking the reference of R value on risks as (R=0.9-1.1) in general population. The ones with very low risk, with low risk, moderate risk, high risk and very high risk were set as R≤0.5, 0.5<R≤0.9, 0.9<R≤1.1, 1.1< R≤2.0 and R>2.0, respectively. The scores of modifiable risk factors were compared with different subgroups of MSM. Results: A total of 4 601 MSM were involved in this study, with the following features presented as: aged 16-64 (28.38±7.11) years, proportions of residence from Guangzhou, Guangdong province or other provinces as 38.6%(1 776/4 601)、35.4%(1 629/4 601) and 26.0%(1 197/4 601), 59.6%(2 742/4 601) received bachelor or above degrees. 81.3%(3 741/4 601) of them claimed as having homosexual orientation. R values of risk level on very low risk, low risk level, moderate risk, high risk and very high risk appeared as 12.9%(594/4 601), 50.9%(2 342/4 601), 17.0%(783/4 601), 14.8%(682/4 601) and 4.3%(200/4 601), respectively. Scores of modifiable risk factors decreased year by year (P<0.05), among MSM in this study. In either of the groups that experiencing insertive or receptive sex, the ones with heterosexual orientation presented the highest scores of modifiable risk factors (P<0.05). Conclusions: The risk levels on HIV infections called for special attention among the users of the self-evaluation network system. Among the MSM that carrying either insertive or receptive sex role, the ones with heterosexual orientation had the highest risk levels and scores of modifiable risk factors in Guangzhou. Further study should be explored to better understand the causes of related risks.

[Status quo and characteristic analysis among MSM-users of the "Internet Plus-based AIDS Comprehensive Prevention Service System" in Guangzhou]

Objective: To analyze the characteristics of the "Interner Plus-based AIDS Comprehensive Prevention Service System" among MSM who frequently using the Internet in Guangzhou. Methods: An online survey was conducted among MSM who were recruited through gay-website portals between August and September, 2018 in Guangzhou, to collect information regarding the use of and attitudes on the "Interner Plus-based AIDS Comprehensive Prevention Service System" . Logistic regression was used to explore the association between the use of Internet intervention tools and related behavioral characteristics. Information on the awareness of AIDS, HIV testing, and condomless anal sex behavior were compared between the core or non-core services users. Results: A total of 777 Internet-based MSM were recruited as participants including 638 men (82.1%) as core service users. MSM were satisfied in using the the "Interner Plus-based AIDS Comprehensive Prevention Service System" while more than 80.0% of the users felt that the tools were helpful in: increasing the HIV awareness, promoting test uptake, and reducing those related risk behavior. Comparing with those who did not use the tools, the users showed higher rates in practising condomless anal intercourse (1.50-1.86 times), commercial sex with men (11.60-21.21 times), and unprotected vaginal intercourse (13.62-20.67 times), in the last 6 months. Proportions of core service users appeared as: [96.6% vs. 74.8%, aOR (95%CI): 8.80 (4.85-15.97)] on HIV testing, [56.4% vs. 22.3%, aOR (95%CI): 4.54 (2.94-7.02)] on regular HIV testing and [86.2% vs. 80.6%, aOR (95%CI): 1.75 (1.06-2.89)] on awareness of HIV knowledge respectively, which were all significantly higher than the non-core service users. Conclusions: The frequent Internet using MSM in Guangzhou claimed to have had high acceptance and satisfaction on the local Internet HIV intervention service tools. The "Internet Plus-based AIDS Comprehensive Prevention Service System" had effectively reached the high-risk subgroups of MSM, increasing the awareness on related risk and promoting testing on HIV.

Transport evidence of asymmetric spin-orbit coupling in few-layer superconducting 1Td-MoTe2

Two-dimensional transition metal dichalcogenides MX₂ (M = W, Mo, Nb, and X = Te, Se, S) with strong spin-orbit coupling possess plenty of novel physics including superconductivity. Due to the Ising spin-orbit coupling, monolayer NbSe₂ and gated MoS₂ of 2H structure can realize the Ising superconductivity, which manifests itself with in-plane upper critical field far exceeding Pauli paramagnetic limit. Surprisingly, we find that a few-layer 1T_d structure MoTe₂ also exhibits an in-plane upper critical field which goes beyond the Pauli paramagnetic limit. Importantly, the in-plane upper critical field shows an emergent two-fold symmetry which is different from the isotropic in-plane upper critical field in 2H transition metal dichalcogenides. We show that this is a result of an asymmetric spin-orbit coupling in 1T_d transition metal dichalcogenides. Our work provides transport evidence of a new type of asymmetric spin-orbit coupling in transition metal dichalcogenides which may give rise to novel superconducting and spin transport properties.

[Effects and safety of quadratus lumborum block in analgesia after hip arthroplasty]

Objective: To evaluate the efficacy of ultrasound guided quadratus lumborum block combined with non-steroidal anti-inflammatory drugs for postoperative analgesia in patients undergoing total hip arthroplasty. Methods: From January to June 2017, sixty American Society of Anesthesiologists (ASA) physical status Ⅰ to Ⅲ patients, aged 55-75 yr, scheduled for total hip arthroplasty, were randomly divided into control group(group N) and quadratus lumborum block (group R). Ultrasound guided quadratus lumborum block was implemented on the affected side at the end of operation.Then 30 ml 0.33% ropivacaine were administrated in group R, while the control group did not receive the same block. A sufentanil patient-controlled analgesia pump was connected to the patient. The rest visual analogue score (VAS) were recorded at 0 h(T(0)), 3 h(T(1)), 6 h (T(2)), 12 h(T(3)), 24 h (T(4)), 36 h (T(5)) and 48 h(T(6)) after sugery, the VAS scores on movement were evaluated at T(4), T(5) and T(6) time points.The consumption of sufentanil within each period time were recorded.The maximal flexion and abduction degrees of the hip joint were evaluated at 12, 24, 36 and 48 h after operation. The number of patients for rescue pain relief by intravenous analgesia pump during 24 h and 48 h after surgery were counted in both groups. The postoperative adverse effects and overall satisfaction in the two groups were recorded. Results: The VAS at rest in group R were 0.8±0.4, 1.0±0.3, 1.2±0.5, 2.0±0.5, 1.7±0.4 , 1.6±0.5 at T(1), T(2), T(3), T(4), T(5), T(6) respectively, and those in group N were 3.0±0.7, 3.5±0.9, 3.8±0.9, 3.3±1.1, 3.3±0.7, 3.0±0.7 at the same time points. The VAS at rest were lower in group R than those in control group at all time points (F=203.090, 216.354, 203.956, 35.548, 96.332, 80.577, all P<0.01). The VAS on movement in group R were 2.7±0.9, 2.9±0.7 , 2.0±0.6 at T(4), T(5), T(6) respectively , and those in group N were 6.0±1.5, 5.8±1.1, 4.5±1.0. The VAS on movement were also lower in group R than those in control group(F=154.561, 143.224, 141.479, all P<0.01). The maximum flexion degrees in group R were (61±12)degrees, (64±10)degrees, (69±15)degrees and(78±19)degrees at 12, 24, 36, 48 h after operation, and those were (45±11) degrees, (49±10)degrees, (52±12)degrees and(60±14)degrees at the same time points. The maximum flexion degrees in group R were increased more than control group at 12, 24, 36, 48 h after operation(F=34.981, 35.575, 52.106, 41.681, all P<0.01). The abduction degrees in group R were(22±6)degrees, (26±6)degrees, (27±8)degrees and(28±7)degrees at 12, 24, 36, 48 h after surgery, and those in group N were (14±5) degrees, (17±6)degrees, (20±6)degrees and(20±5)degrees. The abduction degrees in group R were increased more than those in group N(F=58.974, 33.402, 19.151, 20.575, all P<0.01). The rates of rescue analgesia for pain relief were 10% and 16.7% at 24 h and 48 h after operation respectively in group R, and those were 100% and 100% in group N. Compared to group N, the rates of rescue analgesia for pain relief in group R were significantly decreased (χ(2)=49.091, 42.857, all P<0.01). The incidences of postoperative nausea and vomiting, pruritus in group R were 3.3% and 3.3% respectively, and those in group N were 23.3% and 20.0%. The incidences of nausea and vomiting, pruritus in group R were lower than those in group N (χ(2)=5.192, 4.875, all P<0.01). The overall satisfaction scores in group R (3.7 ± 1.0 ) were higher than those (1.9±0.7) in the group N(t=7.841, P<0.01). Conclusion: The quadratus lumborum block combined with parecoxib sodium for multimodal analgesia after total hip arthroplasty is effective and provides satisfactory analgesia.

Spinon Fermi Surface in a Cluster Mott Insulator Model on a Triangular Lattice and Possible Application to 1T-TaS_{2}

1T-TaS_{2} is a cluster Mott insulator on the triangular lattice with 13 Ta atoms forming a star of David cluster as the unit cell. We derive a two-dimensional XXZ spin-1/2 model with a four-spin ring exchange term to describe the effective low energy physics of a monolayer 1T-TaS_{2}, where the effective spin-1/2 degrees of freedom arises from the Kramers degenerate spin-orbital states on each star of David. A large scale density matrix renormalization group simulation is further performed on this effective model and we find a gapless spin liquid phase with a spinon Fermi surface at a moderate to large strength region of the four-spin ring exchange term. All peaks in the static spin structure factor are found to be located on the "2k_{F}" surface of a half-filled spinon on the triangular lattice. Experiments to detect the spinon Fermi surface phase in 1T-TaS_{2} are discussed.

An unusual continuous paramagnetic-limited superconducting phase transition in 2D NbSe 2

Time reversal and spatial inversion are two key symmetries for conventional Bardeen-Cooper-Schrieffer (BCS) superconductivity ¹ . Breaking inversion symmetry can lead to mixed-parity Cooper pairing and unconventional superconducting properties^1-5. Two-dimensional (2D) NbSe₂ has emerged as a new non-centrosymmetric superconductor with the unique out-of-plane or Ising spin-orbit coupling (SOC)^6-9. Here we report the observation of an unusual continuous paramagnetic-limited superconductor-normal metal transition in 2D NbSe₂. Using tunelling spectroscopy under high in-plane magnetic fields, we observe a continuous closing of the superconducting gap at the upper critical field at low temperatures, in stark contrast to the abrupt first-order transition observed in BCS thin-film superconductors^10-12. The paramagnetic-limited continuous transition arises from a large spin susceptibility of the superconducting phase due to the Ising SOC. The result is further supported by self-consistent mean-field calculations based on the ab initio band structure of 2D NbSe₂. Our findings establish 2D NbSe₂ as a promising platform to explore novel spin-dependent superconducting phenomena and device concepts ¹ , such as equal-spin Andreev reflection ¹³ and topological superconductivity^14-16.

The emergence of Dirac points in photonic crystals with mirror symmetry

We show that Dirac points can emerge in photonic crystals possessing mirror symmetry when band gap closes. The mechanism of generating Dirac points is discussed in a two-dimensional photonic square lattice, in which four Dirac points split out naturally after the touching of two bands with different parity. The emergence of such nodal points, characterized by vortex structure in momentum space, is attributed to the unavoidable band crossing protected by mirror symmetry. The Dirac nodes can be unbuckled through breaking the mirror symmetry and a photonic analog of Chern insulator can be achieved through time reversal symmetry breaking. Breaking time reversal symmetry can lead to unidirectional helical edge states and breaking mirror symmetry can reduce the band gap to amplify the finite size effect, providing ways to engineer helical edge states.

Chiral tunneling in a twisted graphene bilayer

The perfect transmission in a graphene monolayer and the perfect reflection in a Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in a twisted graphene bilayer show an adjustable probability of chiral tunneling for normal incidence: they can be changed from perfect tunneling to partial or perfect reflection, or vice versa, by controlling either the height of the barrier or the incident energy. As well as addressing basic physics about how the chiral fermions with different chiralities tunnel through a barrier, our results provide a facile route to tune the electronic properties of the twisted graphene bilayer.

[Two new flavanone glycosides from Glycyrrhizia inflata]

Two new flavanone glycosides having two chains of sugar moeity were isolated from the roots of Glycyrrhizia inflata Bat by repeated CC and HPLC. They were identified to be liquiritigenin-7-O-beta-D-apiofuranosyl-4'-O-beta-D-glucopyranoside(I) and liquiritigenin-7-O-beta-D-(3-O-acetyl)-apiofuranosyl-4'-O-beta-D- glucopyranoside (II) on the basis of chemical and spectroscopic methods.

Cytochalasin D from Hypocrella bambusae

Cytochalasin D which shows marked cytotoxic effects on multi-tumor cells was newly isolated at high content(5.28 mg/g, dry weight) from Fungus Hypocrella bambusae(B.et Br.) Sacc. Its structure was elucidated by spectroscopic methods. Two-dimensional NMR techniques were applied to make complete assignment for the 1H- and 13C-NMR chemical shifts of this compound.

[Use of high-field nulear magnetic resonance spectroscopy for the analysis of stereoselective metabolites of ibuprofen (R)-enantiomer in rat urine]

AIM

To study the metabolic chiral inversion and chiral metabolites of R-(-)-ibuprofen.

METHODS

Following administration of R-(-)-ibuprofen (250 mg.kg-1), analysis was performed on rat urine purified extracts obtained by solid phase extraction onto C-18 bonded silica gel, then the metabolites of ibuprofen were detected and identified by 1HNMR spectroscopy.

RESULTS

Except for a little ibuprofen, there were 2'-hydroxy-ibuprofen and its glucuronide, 1'-carboxy-ibuprofen glucuronide and ibuprofen glucuronide in rat urine. 2'-hydroxy-ibuprofen is the main metabolite. 1'-carboxy-ibuprofen glucuronide and ibuprofen glucuronide were diastereoisomers.

CONCLUSION

There was the phenomenon of metabolic chiral inversion, whereby the R-enantiomer is transformed in vivo to its active S-antipode via an unusual process.

Pharmacology of radioiodinated hexadecenoic acid--a myocardial imaging agent

123I- and 131I-labeled hexadecenoic acid (IHDA, radiochemical purity over 92%, dissolved in 6% bovine serum albumin solution) was investigated in vivo. ICR mice were administered IHDA via the tail vein. Maximum myocardial uptake (27.3 +/- 5.1%) was reached about 0.5 min after the injection. The ratio of uptake in the heart to that in the lungs was 2.3, to that in liver 1.5 and to that in other organs 2.4 to 6.4. The dog myocardium was visualized distinctly within 3-5 min with a gamma camera after i.v. 131I-IHDA, and not interfered with by activities in the lungs, liver and other organs. The low blood levels at 20 min had little effect on the quality of the heart images.