Direct evidence for a magnetic f-electron–mediated pairing mechanism of heavy-fermion superconductivity in CeCoIn5

To identify the microscopic mechanism of heavy-fermion Cooper pairing is an unresolved challenge in quantum matter studies; it may also relate closely to finding the pairing mechanism of high-temperature superconductivity. Magnetically mediated Cooper pairing has long been the conjectured basis of heavy-fermion superconductivity but no direct verification of this hypothesis was achievable. Here, we use a novel approach based on precision measurements of the heavy-fermion band structure using quasiparticle interference imaging to reveal quantitatively the momentum space (k-space) structure of the f-electron magnetic interactions of CeCoIn₅. Then, by solving the superconducting gap equations on the two heavy-fermion bands Ekα,β with these magnetic interactions as mediators of the Cooper pairing, we derive a series of quantitative predictions about the superconductive state. The agreement found between these diverse predictions and the measured characteristics of superconducting CeCoIn₅ then provides direct evidence that the heavy-fermion Cooper pairing is indeed mediated by f-electron magnetism.Superconductivity of heavy fermions is of abiding interest, both in its own right (1–7) and because it could exemplify the unconventional Cooper pairing mechanism of high-temperature superconductors (8–11). Heavy-fermion compounds are intermetallics containing magnetic ions in the 4f- or 5f-electronic state within each unit cell. At high temperatures, each f-electron is localized at a magnetic ion (Fig. 1A). At low temperatures, interactions between f-electron spins (red arrows Fig. 1A) lead to the formation of a narrow but the subtly curved f-electron band εkf near the chemical potential (red curve, Fig. 1B), and Kondo screening hybridizes this band with the conventional c-electron band εkc of the metal (black curve, Fig. 1B). As a result, two new heavy-fermion bands Ekα,β (Fig. 1C) appear within a few millielectron volts of the Fermi energy. Their electronic structure is controlled by the hybridization matrix element s_k for interconversion of conduction c-electrons to f-electrons and vice-versa, such thatEkα,β=εkc+εkf2±(εkc−εkf2)2+sk2.[1]The momentum structure of the narrow bands of hybridized electronic states (Eq. 1 and Fig. 1C, blue curves at left) near the Fermi surface then directly reflects the form of magnetic interactions encoded within the parent f-electron band εkf. It is these interactions that are conjectured to drive the Cooper pairing (1–5) and thus the opening up of a superconducting energy gap (Fig. 1C, yellow curves at right).Open in a separate windowFig. 1.Effects of f-electron magnetism in a heavy-fermion material. (A) The magnetic subsystem of CeCoIn₅ consists of almost localized magnetic f-electrons (red arrows) with a weak hopping matrix element yielding a very narrow band with strong magnetic interactions between the f-electron spins. (B) The heavy f-electron band is shown schematically in red and the light c-electron band in black. (C) On the left, schematic of the result of hybridizing the c- and f-electrons in B into new composite electronic states referred to as heavy fermions (blue). On the right, the opening of a superconducting energy gap is schematically shown by back-bending bands near the chemical potential. The microscopic interactions driving Cooper pairing of these states, and thus of heavy-fermion superconductivity, have not been identified unambiguously for any heavy-fermion compound.     

山药饮片中外源性有害物质残留情况分析

目的：了解山药饮片中外源性有害物质的残留状况。方法：依据《中华人民共和国药典》和探索性研究方法对不同来源的山药饮片中的二氧化硫残留量、脱硫剂、重金属及有害元素、农药残留进行分析和评价。结果：168批样品中检出11批二氧化硫残留量超标,检出1批使用了脱硫剂;37批样品中检出2批汞元素超标;38批样品中检出5批含有国家禁用和限用农药残留（涕灭威砜、3-羟基克百威、甲拌磷砜、氟虫腈、杀虫脒）,检出15批含有植物生长调节剂残留。结论：山药饮片中外源性有害物质以二氧化硫和农药残留为主,需要进一步加强生产监管,建议完善现行质量标准对农药残留进行限量控制。     

Analysis of six heavy metals in Ortho mineral trioxide aggregate and ProRoot mineral trioxide aggregate by inductively coupled plasma–optical emission spectrometry

Ortho mineral trioxide aggregate (MTA) is a mineral aggregate newly developed for perforation repair, root end filling and pulp capping. The aim of this study was to investigate the levels of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) in Ortho MTA and ProRoot MTA. A total of 0.2 g of each MTA was digested using a mixture of hydrochloric and nitric acids and filtered. Six heavy metals in the resulting filtrates were analyzed by inductively coupled plasma–optical emission spectrometry (n = 5). The results were statistically analyzed using the Mann–Whitney U‐test. The concentrations of Cd, Cu, Fe, Mn, Ni and Zn in Ortho MTA were 0.10, 7.73, 49.51, 2.58, 0.82 and 10.09 p.p.m., respectively. The concentrations of Cd, Cu, Fe, Mn, Ni and Zn in ProRoot MTA were 0.16, 9.38, 1438.11, 74.51, 18.98 and 4.05 p.p.m., respectively. In conclusion, Ortho MTA had lower levels of Cd, Cu, Fe, Mn and Ni than ProRoot MTA.     

The outcome of endometrial ablation in women with inherited bleeding disorders

There are currently limited data on the use of endometrial ablation in the treatment of heavy menstrual bleeding (HMB) in women with inherited bleeding disorders (IBDs). A retrospective review of prospectively collected data was performed. Twelve women with IBDs who had received endometrial ablation for the treatment of HMB were identified and their records reviewed. Details of their menstrual history; quality of life (QOL) and amount of menstrual blood loss [as assessed by pictorial blood-loss assessment chart (PBAC) and haemoglobin (Hb) concentration] pre and post-ablation were collected. Twelve women were included. The median duration of follow-up post-ablation was 32 months (range, 6-76). The median duration of menstruation decreased from 11 to 0 days after treatment (P = 0.004). Median PBAC scores decreased from 1208 preop to 0 post-ablation (P = 0.002).The median Hb concentrations (10.5-13.1 g dL(-1)) and QOL scores (median, 17-54) improved significantly after endometrial ablation (P < 0.01). Endometrial ablation appears to be a safe and effective long-term treatment for HMB in women with IDBs. It significantly decreases menstrual blood loss and improves QOL.     

Structural effects of the slow/b-cardiac myosin heavy chain R453C mutation in cardiac and skeletal muscle

Objectives. Hypertrophic cardiomyopathy (HCM) represents an important cause of sudden cardiac death particularly in otherwise healthy young individuals. In some families, HCM is caused by distinct mutations of the cardiac beta myosin heavy chain gene (MYH7). Design. We have analyzed the expression of the malignant MYH7Arg453Cys mutation, in cardiac and skeletal muscle, and related it to morphological alterations. Results. Morphological investigation revealed hypertrophic cardiomyocytes but regularly arranged myofibrils. Skeletal muscle showed no sign of structural alterations. Conclusions. Our results indicate that cardiomyocyte hypertrophy is secondary, due to impaired function, and that the mutation causes no structural alteration in myofibrillar structure in cardiac or skeletal muscle.     

中药外源性污染物检测技术的现代研究

中药外源性污染物残留现已成为引起中药不良反应的重要原因之一,按照其来源不同主要包括农/兽药残留、重金属污染、真菌毒素残留、病原微生物污染及其他有机污染物残留。对中药的主要外源性污染物的检查对象及检测方法的现代研究进行综述,为补充、完善、提升中药质量安全体系提供参考和依据。     

ICP-MS法测定喜炎平注射液中重金属及有害元素

目的 建立喜炎平注射液中17种重金属及有害元素的含量测定方法。方法 样品经消解后采用电感耦合等离子体质谱（ICP-MS）法测定,射频功率1 550 W;蠕动泵转速0.3 r/s;等离子气体积流量15 L/min;辅助气体积流量0.2 L/min;载气体积流量1 L/min;采样深度10 mm,重复次数为3次。结果 该方法下Li、Al、V、Cr、Fe、Co、Ni、Cu、As、Ag、Cd、Sn、Sb、Ba、Hg、Pb、Bi的检测限分别为9.584、49.858、0.504、3.016、51.209、0.142、1.116、0.675、0.924、1.421、0.403、2.770、0.711、3.584、0.590、0.411、0.169 ng/mL,定量限分别为28.933、151.085、1.528、9.139、155.179、0.429、3.381、2.046、2.799、4.312、1.220、8.394、2.155、10.861、1.965、1.244、0.513 ng/mL,各元素在一定质量浓度范围内,响应值与质量浓度的线性关系良好（r>0.999 1）,进样精密度RSD在0.8%~3.8%（n=12）,重复性RSD在0.7%~2.0%（n=6）,17种元素的加样回收率在95.7%~104.8%。20批大生产样品检测结果：Ag为未检出,Li和V为检出但低于定量限,Al、Ni、Cu、As、Ba、Hg、Pb最大质量浓度分别为0.685、0.013、0.007、0.006、0.208、0.070、0.027 μg/mL,Cr、Fe、Co、Cd、Sn、Sb、Bi为未检出或检出但低于定量限。结论 方法的专属性、线性、灵敏度、精密度、准确度、耐用性等均良好,可用于喜炎平注射液中Li、Al、V、Cr、Fe、Co、Ni、Cu、As、Ag、Cd、Sn、Sb、Ba、Hg、Pb、Bi 17种元素的含量测定,20批大生产样品中17种元素检测结果均小于限度要求,符合规定。     

红杆菌YIM93620和台湾红杆菌BCRC17173培养基优化及~(12)C~(6+)重离子生物学效应研究

目的缩短红杆菌(Rubrobacter sp.)YIM93620和台湾红杆菌(Rubrobacter taiwanensis)BCRC17173培养时间,加快试验进度,更方便研究其耐辐射水平;确定这两株菌对重离子照射后的生物学效应,为航天辐射防护提供理论支持。方法比较这两株菌在TSB、CYC、Thermus、ISP2这四种培养基上的生长情况,并测定添加不同浓度的丙酮酸钠和甜菜碱对生长的促进情况;选E.coli K-12作为阴性对照,分别对这两株菌进行不同剂量的~(12)C~(6+)重离子照射,并绘制致死率曲线研究生物学效应。结果 YIM93620和BCRC17173在Thermus培养基中生长状态最好;分别在添加0.125%甜菜碱和0.1%丙酮酸钠的Thermus培养基中培养时间从10~15 d缩短到6 d;YIM93620在160 Gy时达到最高致死率93.3%,而BCRC17173在320 Gy时致死率仅35.7%,对~(12)C~(6+)重离子都具有强的抗性。结论筛选到这2株菌生长状态都较好的培养基Thermus,添加0.125%甜菜碱和0.1%丙酮酸钠分别可显著促进菌株YIM93620和BCRC17173的生长;这两株菌均有强的耐~(12)C~(6+)重离子辐射特性。