Single-crystal growth, structure and thermal transport properties of the metallic antiferromagnet Zintl-phase ß-EuIn2As2.

Zintl-phase materials have attracted significant research interest owing to the interplay of magnetism and strong spin-orbit coupling, providing a prominent material platform for axion electrodynamics. Here, we report the single-crystal growth, structure, magnetic and electrical/thermal transport properties of the antiferromagnet layer Zintl-phase compound ß-EuIn2As2. Importantly, the new layered structure of ß-EuIn2As2, in rhombohedral (R3̄m) symmetry, contains triangular layers of Eu2+ ions. The in-plane resistivity ρ(H, T) measurements reveal metal behavior with an antiferromagnetic (AFM) transition (TN ∼ 23.5 K), which is consistent with the heat capacity Cp(H, T) and magnetic susceptibility χ(H, T) measurements. Negative MR was observed in the temperature range from 2 K to 20 K with a maximum MR ratio of 0.06. Unique 4f7J = S = 7/2 Eu2+ spins were supposed magnetically order along the c-axis. The Seebeck coefficient shows a maximum thermopower |Smax| of about 40 µV K-1. The kink around 23 K in the Seebeck coefficient originates from the effect of the antiferromagnetic phase on the electron band structure, while the pronounced thermal conductivity peak at around 10 K is attributed to the phonon-phonon Umklapp scattering. The results suggest that the Eu2+ spin arrangement plays an important role in the magnetic, electrical, and thermal transport properties in ß-EuIn2As2, which might be helpful for future potential technical applications.

[Adrenal hemorrhage in a patient with systemic lupus erythematosus].

A 58-year-old female was referred to our department with intermittent suffocation for 1.5 years, aggravated for a month. 1.5 years before she developed oral ulcer, raynaud phenomenon, proteinuria, bilateral pleural effusion, ANA and anti-dsDNA positive. This patient was diagnosed with systemic lupus erythematosus (SLE). After given hormones, hydroxychloroquine sulfate (HCQ), her symptom relieved soon. The patient stopped her pills 1 year ago. One month ago, she had chest tightness, increased urine foam, and suffered from oliguria. Her admission medical examination: blood pressure (BP) 130/80 mmHg, conjunctiva pale, and lower lung breath sounds reduced. There was no tenderness, rebound pain and abdominal muscle tension in the abdomen. Liver and spleen rib inferior, mobile dullness negative, and lower extremity edema. Blood routine tests were performed with hemoglobin (HGB) 57 g/L. Urine routine: BLD (3+). 24-hour urinary protein 3.2 g. serum albumin 20.5 g/L, C-reactive protein (CRP) 12.85 mg/L, erythrocyte sedimentation rate (ESR) 140 mm/h. Antinuclear antibody (ANA) (H)1:10 000, anti-dsDNA antibody 1:3 200; anti-Smith antibody, anti-U1-snRNP/Sm antibody were positive, blood complement 3(C3) 0.43 g/L, complement 4(C4) 0.07 g /L. Anticardiolipin antibody (ACL), anti-ß2-GP1, lupus anticoagulant (LA) were negative; HRCT suggested bilateral medial pleural cavity product liquid. Admission diagnosis: SLE lupus nephritis, anemia, pleural effusion, and hypoproteinemia. We treated her with methylprednisolone 1 000 mg×3 d, late to 48 mg/d and cyclophosphamide 1.0 g, HCQ 0.2 g bid, gamma globulin 10 g×5 d. Day 2 of treatment, this patient developed acute right upper quadrant pain, not accompanied by nausea, vomiting, blood stool and diarrhea. Antipyretic antispasmodic treatment was invalid, after the morning to ease their own abdominal pain. Day 4 of treatment, daytime blood HGB 77 g/L. Bilateral renal vascular ultrasound: bilateral renal artery blood flow velocity was reduced. The abdominal pain of the above symptoms recurred at night, BP was 120/80 mmHg, and no positive signs were found on abdominal examination. No abnormality was found in the vertical abdominal plain film. Blood routine examination: HGB 53 g/L, Plasma D dimer 2 515 µg/L, amylase in hematuria was normal, the stool occult blood was negative. Abdominal computed tomography (CT): normal structure of right adrenal gland disappeared, irregular mass shadow could be seen in adrenal region, CT value was about 50 HU. Morphological density of left adrenal gland was not abnormal. The retroperitoneum descended along the inferior vena cava to the right iliac blood vessel and showed a bolus shadow. The density of some segments increased. The lesion involved the right renal periphery and reached the left side of abdominal aorta. Most lesions surrounded the inferior vena cava, the right renal vein and part of the small intestine. The boundary between the upper lesion and the vena cava was unclear. Iodinecontaining contrast agent was taken orally. No sign of contrast agent overflowing was found in the abdominal cavity. Hematoma and exudative changes were considered in retroperitoneum. CONCLUSION of contrast-enhanced ultrasound of blood vessels: The retroperitoneal inferior vena cava (volume 3.5 cm×3.5 cm×1.5 cm) was hypoechoic and had no blood flow lesion. The adrenal gland had a high possibility of origin. Left renal vein thrombosis extended to inferior vena cava. According to the above data, it was analyzed that the cause of retroperitoneal hematoma of the patient was left adrenal vein thrombosis caused by hypercoagulable state, which led to vascular rupture and hemorrhage caused by increased vascular pressure in adrenal gland. Therefore, on the basis of continuing to actively treat the primary disease, and on the basis of dynamic observation of no active hemorrhage for 3 days, the anticoagulant therapy was continued with 10 mg/d of apixaban. Clinical symptoms were gradually eased, HGB did not decrease. Two weeks later, the ultrasonic examination showed that the irregular cluster hypoechoic range behind the inferior vena cava was significantly smaller than that before (1.8 cm×1.2 cm×0.7 cm). Abdominal CT examination after 1 month showed that there was no abnormal morphological density of bilateral adrenal glands and basic absorption of retroperitoneal exudation. Adrenal hemorrhage is uncommon. SLE with adrenal hemorrhage is rarer. In SLE patients, especially those complicated with APS, if abdominal pain accompanied by HGB decrease occurs, except after gastrointestinal hemorrhage, the possibility of adrenal hemorrhage should be warned.

[Clinical characteristic of 74 cases of malignant tumor in rheumatoid arthritis].

OBJECTIVE: To investigate the clinical characteristics of rheumatoid arthritis (RA) patients with malignant tumor. METHODS: Retrospective summary was made of 1 562 in patients of RA from January 2011 to June 2017. In the study, 74 RA patients with malignant tumor were reviewed and analyzed, and the general conditions, tumor types, RA and tumor onset sequence, and the medication situation were analyzed. RESULTS: The incidence of malignant tumor in the patients with rheumatoid arthritis in our center was 4.16%. The 74 patients were complicated with malignant tumor, of whom 53 were female, and 21 male. The age of RA at presentation was (52.6±17.8) years. The average disease duration of malignant tumor was (63.4 ± 12.7) years. The onset time of rheumatoid arthritis was earlier than that of malignant tumors in 51 cases (51/74), with an average of (17.2±14.2) years between 2 and 60 years. The incidence of malignant tumor was earlier than that of rheumatoid arthritis in 16 cases (16/74), with an average of (6.2±5.9) years between 1 and 21 years, of which 10 cases were sex hormone related tumors. Seven cases (7/74) were diagnosed with RA at the same time, and the time interval between the two diseases was within 1 year. All the patients were over 60 years old with digestive tract tumors. All the 7 patients showed polyarthritis, significantly increased erythrocyte sedimentation rate and C-reactive protein, including 4 rheumatoid factor positive cases and 2 anti-CCP antibody positive cases. The effect of non-steroidal anti-inflammatory drugs and traditional drugs to improve the condition of the disease was poor in the 7 patients, and the condition was relieved after using low-dose glucocorticoids. Gastrointestinal tumors, breast and reproductive system tumors were the most common, followed by respiratory, urological and blood system tumors. CONCLUSION: The risk in patients of rheumatoid arthritis complicated with malignant tumor is higher than that of the general population. A variety of factors play an important role in cancer risk of RA, including disease activity, some estrogen metabolites, the use of drugs and so on. Therefore, all RA patients should be screened for malignant tumor during diagnosis, and malignant tumor surveillance is mandatory for all rheumatoid arthritis patients after diagnosis.

A Preliminary Study of the Value of Plasma microRNA-193b and Soluble Urokinase-Type Plasminogen Activator Receptor in Identifying Patients with Early-Stage Colorectal Cancer and.

BACKGROUND: Early detection and management of colorectal cancer (CRC) and colorectal adenoma (CRA) reduces the mortality and morbidity of CRC, but there is a lack of ideal circulation biomarkers. METHODS: A total of 80 patients with early-stage CRC and CRA and 30 healthy controls were included in this preliminary study. Plasma samples were collected before colonoscopy and prepared for measurement of microRNA193b and soluble uPAR. RESULTS: Plasma level of miR-193b was decreased through the normal-adenoma-carcinoma sequence with no significant difference between patients with CRC and advanced CRA. The AUC of ROC curve evaluating the value of miR-193b in discriminating patients with early stage CRC or advanced CRA from patients with non-advanced CRA or normal control subjects was 0.849 (95% CI 0.773 - 0.923, p < 0.001). Significant alteration of plasma suPAR is only observed in CRC group (p < 0.001). CONCLUSIONS: Plasma miR-193b may be a novel candidate biomarker for screening patients with early-stage CRC and advanced CRA.

Compensated Semimetal LaSb with Unsaturated Magnetoresistance.

By combining angle-resolved photoemission spectroscopy and quantum oscillation measurements, we performed a comprehensive investigation on the electronic structure of LaSb, which exhibits near-quadratic extremely large magnetoresistance (XMR) without any sign of saturation at magnetic fields as high as 40 T. We clearly resolve one spherical and one intersecting-ellipsoidal hole Fermi surfaces (FSs) at the Brillouin zone (BZ) center Γ and one ellipsoidal electron FS at the BZ boundary X. The hole and electron carriers calculated from the enclosed FS volumes are perfectly compensated, and the carrier compensation is unaffected by temperature. We further reveal that LaSb is topologically trivial but shares many similarities with the Weyl semimetal TaAs family in the bulk electronic structure. Based on these results, we have examined the mechanisms that have been proposed so far to explain the near-quadratic XMR in semimetals.

Pressure induced superconductivity on the border of magnetic order in MnP.

We report the discovery of superconductivity on the border of long-range magnetic order in the itinerant-electron helimagnet MnP via the application of high pressure. Superconductivity with T(sc)≈1 K emerges and exists merely near the critical pressure P(c)≈8 GPa, where the long-range magnetic order just vanishes. The present finding makes MnP the first Mn-based superconductor. The close proximity of superconductivity to a magnetic instability suggests an unconventional pairing mechanism. Moreover, the detailed analysis of the normal-state transport properties evidenced non-Fermi-liquid behavior and the dramatic enhancement of the quasiparticle effective mass near P(c) associated with the magnetic quantum fluctuations.

Nearly isotropic superconductivity in (Ba,K)Fe(2)As(2).

Superconductivity was recently observed in iron-arsenic-based compounds with a superconducting transition temperature (T(c)) as high as 56 K, naturally raising comparisons with the high-T(c) copper oxides. The copper oxides have layered crystal structures with quasi-two-dimensional electronic properties, which led to speculation that reduced dimensionality (that is, extreme anisotropy) is a necessary prerequisite for superconductivity at temperatures above 40 K (refs 8, 9). Early work on the iron-arsenic compounds seemed to support this view. Here we report measurements of the electrical resistivity in single crystals of (Ba,K)Fe(2)As(2) in a magnetic field up to 60 T. We find that the superconducting properties are in fact quite isotropic, being rather independent of the direction of the applied magnetic fields at low temperature. Such behaviour is strikingly different from all previously known layered superconductors, and indicates that reduced dimensionality in these compounds is not a prerequisite for 'high-temperature' superconductivity. We suggest that this situation arises because of the underlying electronic structure of the iron-arsenic compounds, which appears to be much more three dimensional than that of the copper oxides. Extrapolations of low-field single-crystal data incorrectly suggest a high anisotropy and a greatly exaggerated zero-temperature upper critical field.

Initial conditions for dark soliton generation in normal-dispersion fiber lasers.

We report results of numerical simulations on the various initial conditions for dark soliton generation in an all-normal-dispersion fiber laser. All the dark solitons generated are odd dark solitons. Differently from the dark soliton generation in fibers, where an arbitrary dip could evolve into a dark soliton, it is found that the dark soliton can originate only from an initial dip with a certain parameter requirement. A bright pulse with either a hyperbolic secant square, Gaussian, or Lorentz profile can be developed into a dark soliton, provided that the parameters of the initial bright pulse are selected. Dark solitons can be generated in fiber lasers only if there is a phase jump, and this phase jump can be maintained and evolve to π during the pulse evolution.

Magnetic order close to superconductivity in the iron-based layered LaO1-xFxFeAs systems.

Following the discovery of long-range antiferromagnetic order in the parent compounds of high-transition-temperature (high-T(c)) copper oxides, there have been efforts to understand the role of magnetism in the superconductivity that occurs when mobile 'electrons' or 'holes' are doped into the antiferromagnetic parent compounds. Superconductivity in the newly discovered rare-earth iron-based oxide systems ROFeAs (R, rare-earth metal) also arises from either electron or hole doping of their non-superconducting parent compounds. The parent material LaOFeAs is metallic but shows anomalies near 150 K in both resistivity and d.c. magnetic susceptibility. Although optical conductivity and theoretical calculations suggest that LaOFeAs exhibits a spin-density-wave (SDW) instability that is suppressed by doping with electrons to induce superconductivity, there has been no direct evidence of SDW order. Here we report neutron-scattering experiments that demonstrate that LaOFeAs undergoes an abrupt structural distortion below 155 K, changing the symmetry from tetragonal (space group P4/nmm) to monoclinic (space group P112/n) at low temperatures, and then, at approximately 137 K, develops long-range SDW-type antiferromagnetic order with a small moment but simple magnetic structure. Doping the system with fluorine suppresses both the magnetic order and the structural distortion in favour of superconductivity. Therefore, like high-T(c) copper oxides, the superconducting regime in these iron-based materials occurs in close proximity to a long-range-ordered antiferromagnetic ground state.

Abrupt change reflected by the van Hove singularity in the optical spectra of CaMn2P2.

The trigonal CaAl2Si2-type structure CaMn2P2has been reported undergoing an exotic first order phase transition at the critical temperatureTN=69.5K. In this paper, we present the optical spectra for theab-plane of CaMn2P2single crystal from 300 K to 10 K for the first time. In the real part of the optical conductivity spectraσ1(ω), a direct gap could be determined at all temperatures without any Drude term visible, i.e., the sample goes through the first order phase transition from one insulator state to the other insulator state. At higher energy, an asymmetric sharp interband transition peak appears in allσ1(ω) spectra, which indicates a divergence of the joint density of states. This sharp peak could be well described by the two dimensional van Hove singularity function. In particular, this peak is very sensitive to the first order phase transition, especially the peak positionEtwhose the most prominent blue shift occurs only when the first order transition happens. Our data and analysis reveal that the first order phase transition leads to a weak partial re-normalization of the band structure. Our study will be useful in further investigations about the mechanism of the first order phase transition in the insulator.

[Efficacy of cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy for pseudomyxoma peritonei].

Objective: To evaluate the efficacy and safety of cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) in the treatment of pseudomyxoma peritonei (PMP). Methods: In this descriptive case series study, we retrospective analyzed the records of PMP patients treated with CRS and HIPEC between January 2013 and June 2023 at Affiliated Cancer Hospital and Institute of Guangzhou Medical University. The inclusion criteria were as follows: (1) Aged 18 to 75 years and nonpregnant women. (2) Histologically confirmed diagnosis of pseudomyxoma peritonei. (3) Karnofsky Performance Scale (KPS)>70. (4) The functions of major organs such as the heart, liver, lungs, and kidneys can tolerate major surgery for long periods of time. (5) No evidence of extra-abdominal metastasis. Patients with extensive intra-abdominal adhesions or severe infectious diseases were excluded. The main outcomes were overall survival (OS) and postoperative major complications. The postoperative major complications were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (version 5.0). We used the peritoneal cancer index (PCI) score to quantitatively assess the peritoneal metastases and the completeness of cytoreduction (CCR) score at the end of surgery (CCR-0 and CCR-1 considered to be complete CRS). Results: A total of the 186 PMP patients with a median age of 56 (interquartile range extremes (IQRE), 48-64) years were included, 65 (34.9%) males and 121 (65.1%) females. The median peritoneal cancer index (PCI) score was 28 (20-34). Appendiceal origin accounted for 91.4%. Histological types were low grade in 99 patients (53.2%), high grade in 57 patients (30.6%), and 55 patients (29.6%) received complete cytoreduction (CCR-0/1). The median operative duration was 300 (211-430) minutes for all patients. Treatment-related 30-day mortality was 2.7%; 90-day mortality 4.3%; reoperation 1.6%; and severe morbidity 43.0%. Within the entire series, anemia(27.4%), electrolyte disturbance(11.6%), and hypoalbuminemia(7.5%) were the most frequent major complications (grade 3-4). The incidences of gastrointestinal anastomotic leakage, abdominal bleeding, and abdominal infection were 2.2%, 2.2%, and 4.3%, respectively. After a median follow-up of 38.1 (95%CI:31.2-45.1) months, the 5-year OS was 50.3% (95%CI: 40.7%-59.9%) with a median survival time of 66.1 (95%CI: 43.1-89.1) months. The survival analysis showed that patients with pathological low grade, low PCI, and low CCR score had better survival with statistically significant differences (all P<0.05). Further stratified into complete and incomplete CRS subgroups, the 5-year OS of the CCR-0 and CCR-1 subgroups was 88.9% (95%CI: 68.3%-100.0%) and 77.6% (95%CI: 62.7%-92.5%), respectively; and 42.0% (95%CI: 29.5%-54.5%) in the CCR-2/3 subgroup. Conclusions: CRS and HIPEC may result in a long-term survival benefit for PMP patients with acceptable perioperative morbidity and mortality. This strategy, when complete CRS is possible, could significantly prolong survival for strictly selected patients at experienced centers.

Demonstrating the pharmacogenetic effects of angiotensin-converting enzyme inhibitors on long-term prognosis of diastolic heart failure.

The objective of this study was to evaluate the effects of angiotensin-converting enzyme (ACE) inhibitors and pharmacogenetic interaction on the survival of the patients with diastolic heart failure (DHF). A total of 285 subjects with DHF confirmed by echocardiography were recruited in the period between 1995 and 2003. Baseline characteristics (age, sex, prior history, medication, and echocardiographic findings) and genetic polymorphisms (ACE gene insertion/deletion (I/D) polymorphism; T174M, M235T, G-6A, A-20C, G-152A, and G-217A polymorphisms of the angiotensinogen (AGT) gene; and A1166C polymorphisms of the angiotensin II type I receptor (AT1R)) were collected and matched (by propensity score) in those who received and those who did not receive ACE inhibitors. The patients were followed up to 10 years. Kaplan-Meier curves and Cox regression models were used to demonstrate the survival trend. The 85 patients who received ACE inhibitors and the other 85 patients who did not were found to have comparable baseline characteristics and polymorphism distribution. Prescription of ACE inhibitors was associated with a significant decrease in overall mortality (hazard ratio (HR), 0.45; 95% confidence interval (CI), 0.24-0.83; P=0.01), and a lower rate of cardiovascular events at 4000 days (HR, 0.53; 95% CI, 0.32-0.90; P=0.02). In addition, ACE I/D gene D allele was associated with higher overall mortality as compared with the I allele (HR, 2.04; P=0.003). This effect was diminished in those who received ACE inhibitors. The use of ACE inhibitor was associated with a significant decrease in long-term mortality and cardiovascular events in the patients with DHF. Genetic variants in the renin-angiotensin system genes were also associated, but their effects could be modified by the use of ACE inhibitors.

Band-dependent quasiparticle dynamics in single crystals of the Ba(0.6)K(0.4)Fe2As2 superconductor revealed by pump-probe spectroscopy.

We report on band-dependent quasiparticle dynamics in Ba(0.6)K(0.4)Fe2As2 (Tc=37 K) measured using ultrafast pump-probe spectroscopy. In the superconducting state, we observe two distinct relaxation processes: a fast component whose decay rate increases linearly with excitation density and a slow component with an excitation density independent decay rate. We argue that these two components reflect the recombination of quasiparticles in the two hole bands through intraband and interband processes. We also find that the thermal recombination rate of quasiparticles increases quadratically with temperature. The temperature and excitation density dependence of the decays indicates fully gapped hole bands and nodal or very anisotropic electron bands.

Ultrafast pump-probe study of phase separation and competing orders in the underdoped (Ba,K)Fe2As2 superconductor.

We report measurements of quasiparticle relaxation dynamics in the high-temperature superconductor (Ba,K)Fe2As2 in optimally doped, underdoped, and undoped regimes. In the underdoped sample, spin-density wave (SDW) order forms at approximately 85 K, followed by superconductivity at approximately 28 K. We find the emergence of a normal-state order that suppresses SDW at a temperature T{*} approximately 60 K and argue that this normal-state order is a precursor to superconductivity.

Angle-resolved photoemission spectroscopy of the iron-chalcogenide superconductor Fe1.03Te0.7Se0.3: strong coupling behavior and the universality of interband scattering.

We have performed angle-resolved photoemission spectroscopy of the iron-chalcogenide superconductor Fe1.03Te0.7Se0.3 to investigate the electronic structure relevant to superconductivity. We observed a holelike Fermi surface (FS) and an electronlike FS at the Brillouin zone center and corner, respectively, which are nearly nested by the Q∼(π,π) wave vector. We do not find evidence for the nesting instability with Q∼(π+δ,0) reminiscent of the antiferromagnetic order in the parent compound Fe1+yTe. We have observed an isotropic superconducting (SC) gap along the holelike FS with the gap size Δ of ∼4 meV (2Δ/kBTc ∼ 7), demonstrating the strong-coupling superconductivity. The observed similarity of low-energy electronic excitations between iron-chalcogenides and iron-arsenides strongly suggests that common interactions which involve Q∼(π,π) scattering are responsible for the SC pairing.

Observation of Dirac cone electronic dispersion in BaFe2As2.

We performed an angle-resolved photoemission spectroscopy study of BaFe2As2, which is the parent compound of the so-called 122 phase of the iron-pnictide high-temperature superconductors. We reveal the existence of a Dirac cone in the electronic structure of this material below the spin-density-wave temperature, which is responsible for small spots of high photoemission intensity at the Fermi level. Our analysis suggests that the cone is slightly anisotropic and its apex is located very near the Fermi level, leading to tiny Fermi surface pockets. The bands forming the cone show an anisotropic leading edge gap away from the cone that suggests a nodal spin-density-wave description.

Effect of therapeutic immunization using Ad5/35 and MVA vectors on SIV infection of rhesus monkeys undergoing antiretroviral therapy.

Antiretroviral therapy (ART) effectively slows the progression of AIDS. However, drug resistance and/or toxicity can limit the utility of ART in many patients. In this study, we assessed whether a viral vector-based vaccine can be used as a therapeutic vaccine in simian immunodeficiency virus (SIV)-infected monkeys. The effect of vaccinating SIVmac239-infected rhesus monkeys with an SIV gag and gp120-expressing adenovirus (Ad) vector vaccine and a modified vaccinia Ankara (MVA) vaccine was explored while being treated with ART. Rhesus monkeys were intravenously infected with 10 and 1000 TCID(50) (50% tissue culture infectious dose) of SIVmac239. Two months after SIV infection, the monkeys received a 4-month treatment with ART. Some of the monkeys were immunized with adenovirus-based vaccine and MVA-based vaccine with 2 months interval during ART. Viral load, CD4 count and SIV-specific immune responses were observed for 7 months after interruption of ART. The vaccinated animals had higher (i) CD4 counts, (ii) SIV-specific cell-mediated immune responses and (iii) anti-SIV-neutralizing antibody (Ab) titers than monkeys treated with ART alone. More importantly, the vaccination significantly reduced the SIV RNA load from animals infected with a low dose of SIV (10 TCID(50)). The anti-SIV cell-mediated and humoral responses induced by the vaccination was inversely correlated with a reduction in SIV viral load and positively correlated with an increase in CD4(+) T cell counts. These results suggest that vaccination can improve antiviral cell-mediated and humoral immunity, which may contribute to controlling viral replication.

Structural and magnetic phase diagram of CeFeAsO(1- x)F(x) and its relation to high-temperature superconductivity.

Recently, high-transition-temperature (high-Tc) superconductivity was discovered in the iron pnictide RFeAsO(1-x)F(x) (R, rare-earth metal) family of materials. We use neutron scattering to study the structural and magnetic phase transitions in CeFeAsO(1-x)F(x) as the system is tuned from a semimetal to a high-Tc superconductor through fluorine (F) doping, x. In the undoped state, CeFeAsO develops a structural lattice distortion followed by a collinear antiferromagnetic order with decreasing temperature. With increasing fluorine doping, the structural phase transition decreases gradually and vanishes within the superconductivity dome near x=0.10, whereas the antiferromagnetic order is suppressed before the appearance of superconductivity for x>0.06, resulting in an electronic phase diagram remarkably similar to that of the high-Tc copper oxides. Comparison of the structural evolution of CeFeAsO(1-x)F(x) with other Fe-based superconductors suggests that the structural perfection of the Fe-As tetrahedron is important for the high-Tc superconductivity in these Fe pnictides.

Transport properties and the large anisotropic magnetoresistance of Cu(x)NbS(2) single crystals.

The transport properties of Cu(x)NbS(2) (x = 0.09, 0.44 and 0.55) single crystals were systematically studied. The in-plane and out-of-plane resistivities decrease with increasing Cu content, and a transition with hysteresis shows up for the crystals with x = 0.44 and 0.55. The thermopower and Hall coefficient of Cu(x)NbS(2) show opposite signs, indicating that there are two kinds of carriers in this system. The angular dependences of the in-plane magnetoresistance (MR(ab) = (ρ(ab)(H)-ρ(ab)(0))/ρ(ab)(0) × 100%) at different temperatures were also studied. The single crystals with x = 0.44 and 0.55 show a strong anisotropic MR(ab). For the x = 0.55 sample, MR(ab) reaches 80% with a magnetic field of 14 T applied along the c-axis, while MR(ab) is less than 5% for the magnetic field applied within the ab-plane. These results can be well understood in the light of the anisotropic Fermi surface in the multiband system.