Switchable hardening of a ferromagnet at fixed temperature

The intended use of a magnetic material, from information storage to power conversion, depends crucially on its domain structure, traditionally crafted during materials synthesis. By contrast, we show that an external magnetic field, applied transverse to the preferred magnetization of a model disordered uniaxial ferromagnet, is an isothermal regulator of domain pinning. At elevated temperatures, near the transition into the paramagnet, modest transverse fields increase the pinning, stabilize the domain structure, and harden the magnet, until a point where the field induces quantum tunneling of the domain walls and softens the magnet. At low temperatures, tunneling completely dominates the domain dynamics and provides an interpretation of the quantum phase transition in highly disordered magnets as a localization/delocalization transition for domain walls. While the energy scales of the rare earth ferromagnet studied here restrict the effects to cryogenic temperatures, the principles discovered are general and should be applicable to existing classes of highly anisotropic ferromagnets with ordering at room temperature or above.     

Tumor treating fields in combination with gemcitabine or gemcitabine plus nab-paclitaxel in pancreatic cancer: Results of the PANOVA phase 2 study

Background

Tumor Treating Fields (TTFields), low intensity alternating electric fields with antimitotic activity, have demonstrated survival benefit in patients with glioblastoma. This phase 2 PANOVA study was conducted to examine the combination of TTFields plus chemotherapy in patients with pancreatic ductal adenocarcinoma (PDAC).

庆大霉素C组分和有关物质测定的HPLC-柱后衍生化法与脉冲安培电化学法的比较研究

摘 要 目的： 参考《欧洲药典》的HPLC 脉冲安培电化学法建立高效液相色谱 柱后衍生化法测定庆大霉素C组分含量及其有关物质, 同时与电化学法进行比较研究。方法: 采用亲水性HydrosphereC₁₈（250 mm×4.6 mm,5 μm）色谱柱,以含0.7%三氟乙酸及0.025%五氟丙酸的50 mmol·L^-1氢氧化钠溶液（pH2.6）-乙腈（98.5∶1.5）为流动相。衍生化法反应温度30℃,荧光激发波长340 nm,发射波长430 nm。电化学法采用脉冲安培检测器,金电极为工作电极,四电位波形工作模式。结果:两种方法测定的庆大霉素C组分（C_1a, C₂, C_2a和C₁）分别在5.82～233.00,6.92～277.00,4.00～160.00和6.23～249.00 μg·mL^-1的浓度范围内线性关系良好（r均≥0.999 3）,检测限和定量限范围分别为0.92～3.28 ng和1.37～5.19 ng。结论: 两种方法的检测结果无明显差异。     

Nanocomposite Foams of Polypropylene and Carbon Nanotubes: Preparation,Characterization, and Evaluation of their Performance as EMI Absorbers

Highly expanded nanocomposite foams of polypropylene and carbon nanotubes (PP/CNT) are formed using supercritical carbon dioxide (scCO₂) technology. The foaming parameters (temperature, pressure) are investigated to establish their influence on the morphology of the resulting foams and their impact on the electrical conductivity. As promising electromagnetic‐interference (EMI) absorbers, the EMI shielding performance of the foams is determined, and a preliminary relationship is established between foam morphology and the EMI shielding performance. The best candidates are highly expanded foams with a volume expansion of >25, containing 0.1 vol% CNTs; they are able to absorb more than 90% of the incident radiation between 25 and 40 GHz.

     

A three‐dimensional point process model for the spatial distribution of disease occurrence in relation to an exposure source

We study methods for how to include the spatial distribution of tumours when investigating the relation between brain tumours and the exposure from radio frequency electromagnetic fields caused by mobile phone use. Our suggested point process model is adapted from studies investigating spatial aggregation of a disease around a source of potential hazard in environmental epidemiology, where now the source is the preferred ear of each phone user. In this context, the spatial distribution is a distribution over a sample of patients rather than over multiple disease cases within one geographical area. We show how the distance relation between tumour and phone can be modelled nonparametrically and, with various parametric functions, how covariates can be included in the model and how to test for the effect of distance. To illustrate the models, we apply them to a subset of the data from the Interphone Study, a large multinational case‐control study on the association between brain tumours and mobile phone use. Copyright © 2015 John Wiley & Sons, Ltd.     

Combining electromagnetic navigation and 3‐D mapping to reduce fluoroscopy time and achieve optimal CRT response

Implantation of cardiac resynchronization therapy (CRT) devices can be challenging, time consuming, and associated with high‐dose x‐ray exposure. We present the technique in which an electromagnetic navigation system (MediGuideTM, St. Jude Medical) and an electroanatomical three‐dimensional mapping system (EnSite NavX, St Jude Medical) are usefully combined for implanting implantable cardioverter defibrillator CRT devices with strong reduction of x‐ray exposure, and for targeting the most delayed regions in the activation maps avoiding scars for optimal CRT response.     

A case of electromagnetic interference between HeartMate 3 LVAD and implantable cardioverter defibrillator

Implantable cardioverter defibrillators (ICDs) have been shown to have a significant benefit in reducing sudden cardiac death (SCD) in patients with systolic heart failure. Additionally, cardiac devices as a bridge to transplant or destination therapy are often used in patients with end‐stage systolic heart failure. As a result, most patients with left ventricular assist devices (LVADs) also have an ICD. Here, we present an electromagnetic interference (EMI) between HeartMate 3 LVAD and ICD. This issue might be critical for both electrophysiologists and advanced heart failure cardiologists to understand prior to implantation of ICD/LVADs in these patients.     

An unusual source of electromagnetic interference

A 62‐year‐old male presented to his treating cardiologist for routine interrogation of his implantable cardiac defibrillator on the background of severe ischemic cardiomyopathy and end‐stage kidney disease on hemodialysis. The device log revealed multiple paroxysms of atrial fibrillation; however, upon scrutinizing these episodes it was evident that they always corresponded to episodes of hemodialysis while dialyzing through a chronic dialysis catheter, but not while dialyzing via an arteriovenous fistula. We report the novel finding of inappropriate sensing of current leak from the catheter by a lead with a floating atrial dipole.