Heat Capacity and Thermal Conductance Measurements of a Superconducting-Normal Mixed State by Detection of Single 3 eV Photons in a Magnetic Penetration Thermometer

We report on measurements of the detected signal pulses in a molybdenum-gold Magnetic Penetration Thermometer (MPT) in response to absorption of one or more 3 eV photons. We designed and used this MPT sensor for x-ray microcalorimetry. In this device, the diamagnetic response of a superconducting MoAu bilayer is used to sense temperature changes in response to absorbed photons, and responsivity is enhanced by a Meissner transition in which the magnetic flux penetrating the sensor changes rapidly to minimize free energy in a mixed superconducting normal state. We have previously reported on use of our MPT to study a thermal phonon energy loss to the substrate when absorbing x-rays. We now describe results of extracting heat capacity C and thermal conductance G values from pulse height and decay time of MPT pulses generated by 3 eV photons. The variation in C and G at temperatures near the Meissner transition temperature (set by an internal magnetic bias field) allow us to probe the behavior in superconducting normal mixed state of the condensation energy and the electron cooling power resulting from quasi-particle recombination and phonon emission. The information gained on electron cooling power is also relevant to the operation of other superconducting detectors, such as Microwave Kinetic Inductance Detectors

Superconducting Effects in Optimization of Magnetic Penetration Thermometers for X-ray Microcalorimeters

Like MMCs, MPTs enable high energy microcalorimeters with zero bias power dissipation and potential resolution < 1 eV. MPTs can provide d(phi)/dT as large as 1000 (Phi)(sub 0)/K, with no excess noise, thereby reducing the importance of SQUID noise. Long coherence length in a Type-I superconducting MoAu film offers multiple advantages for efficient flux expulsion in MPT. Region of steepest d(phi)/dT is the Meissner effect in the small device; flux is expelled/penetrates to minimize free energy. Steepness of transition can be engineered with choice of film thickness and coil pitch relative to lambda(sub eff)(0), ratio of T/T(sub c), and bias circuit inductance

Performance and Characterization of Magnetic Penetration Thermometer Devices for X-Ray Spectroscopy

We are developing magnetic penetration thermometers (MPTs) for applications in X-ray astronomy. These non-dissipative devices consist of an X-ray absorber in good thermal contact to a superconducting thin film with a transition temperature around T=100mK. A microfabricated superconducting planar inductor underneath is used to store a persistent current and couple the superconductor's diamagnetic response to a readout SQUID. The strong temperature dependence of the diamagnetic response make these devices suitable for highly sensitive macroscopic thermometers that are capable of achieving very high energy resolution. We present results achieved with MPTs consisting of MoAu bilayer sensors attached to overhanging square 250 micron by 250 micron gold absorbers that have demonstrated an energy resolution of delta E_FWHM=2.3eV at an X-ray energy of 5.9keV. A similar device has shown delta E_FWHM=2.0eV at 1.5 keV. Under certain conditions and for specific device geometries, the temperature responsivity of the MPTs can vary on long timescales degrading the spectral performance. We present the characterization of different inductor geometries to optimize the design for the highest possible temperature sensitivity and compare different device designs with respect to responsivity stability

Magnetic Penetration Effects in Small Superconducting Devices

The temperature dependent behavior of a superconducting body in an applied magnetic field involves flux penetration/expulsion both from screening currents (within a magnetic penetration depth) and variations in the superconducting order parameter (locally to form vortices or a mixed state, or globally in the Meissner effect). The temperature dependence of the magnetic penetration depth, in particular, has been used to make highly sensitive macroscopic thermometers. For the microscopic device volumes required in sensitive low temperature photon detectors, properties of actual thin film materials, non-uniformity of applied magnetic fields, and the influence of measurement circuit dynamics are complicating factors. We discuss the various penetration effects as demonstrated in a particularly promising combination of material and geometry that we have used to make sensitive x-ray microcalorimeters

Multiple actions of pifithrin-α on doxorubicin-induced apoptosis in rat myoblastic H9c2 cells

Doxorubicin (Dox) is a chemotherapeutic agent that causes significant cardiotoxicity. We showed previously that Dox activates p53 and induces apoptosis in mouse hearts. This study was designed to elucidate the molecular events that lead to p53 stabilization, to examine the pathways involved in Dox-induced apoptosis, and to evaluate the effectiveness of pifithrin-α (PFT-α), a p53 inhibitor, in blocking apoptosis of rat H9c2 myoblasts. H9c2 cells that were exposed to 5 μM Dox had elevated levels of p53 and phosphorylated p53 at Ser15. Dox also triggered a transient activation of p38, p42/p44ERK, and p46/p54JNK MAP kinases. Caspase activity assays and Western blot analysis showed that H9c2 cells treated with Dox for 16 h had marked increase in the levels of caspases-2, -3, -8, -9, -12, Fas, and cleaved poly(ADP ribose) polymerase (PARP). There was a concomitant increase in p53 binding activity, cytochrome c release, and apoptosis. These results suggest that Dox can trigger intrinsic, extrinsic, and endoplasmic reticulum-associated apoptotic pathways. Pretreatment of cells with PFT-α followed by Dox administration attenuated Dox-induced increases in p53 levels and p53 binding activity and partially blocked the activation of p46/p54JNK and p42/p44ERK. PFT-α also led to decreased levels of caspases-2, -3, -8, -9, -12, Fas, PARP, cytochrome c release, and apoptosis. Our results suggest that p53 stabilization is a focal point of Dox-induced apoptosis and that PFT-α interferes with multiple steps of Dox-induced apoptosis

Tratamiento quirúrgico de la hidrocefalia en un paciente canino: reporte de caso Surgical treatment of hydrocephalus in a dog: a case report

La hidrocefalia es una acumulación excesiva de liquido cefalorraquídeo (LCR) en el sistema ventricular cerebral como consecuencia de una causa primaria. Esta enfermedad puede ser adquirida o congénita, manifestándose con signos clínicos de enfermedad neurológica. Este artículo presenta una revisión sobre la fisiopatología, diagnóstico y tratamiento médico quirúrgico de la hidrocefalia en un paciente canino atendido en el Centro de Medicina Veterinaria y de Zootecnia del CES (Medellín, Colombia). En el paciente se realizó una derivación ventrículo peritoneal como tratamiento quirúrgico de la enfermedad; la cirugía se llevó a cabo sin complicaciones y se obtuvo una recuperación satisfactoria con reversión progresiva de la sintomatología clínica. La derivación ventrículo peritoneal como opción quirúrgica para el tratamiento de la hidrocefalia en caninos se convierte entonces en una herramienta valiosa para el médico veterinario, la cual le permite establecer un pronóstico más esperanzador respecto a la longevidad y calidad de vida del paciente.<br>Hydrocephalus is an excessive accumulation of cerebrospinal fluid (CSF) in the cerebral ventricular system of the brain as a result of a primary cause. This disease can be acquired or congenital, pronouncing itself with clinical signs of neurological disease. This article presents a clinical case with a detailed description of the physiopathology, diagnosis and surgical treatment of hydrocephalus in a canine patient that was attended at the Centro de Medicina Veterinaria y Zootecnia CES (Medellín, Colombia). In this patient a ventricle to peritoneal derivation was practiced as a surgical treatment of the disease; the surgery was carried out without complications and a satisfactory recovery with progressive reversion of the clinical symptomatology was obtained. The ventricle to peritoneal derivation is a surgical option for the treatment of hydrocephalus in canine that becomes a valuable tool for veterinarians, which allows them to establish a more hopeful prognosis regarding longevity and quality of life of the patient

Tratamiento quirúrgico de la hidrocefalia en un paciente canino: reporte de caso

Hydrocephalus is an excessive accumulation of cerebrospinal fluid (CSF) in the cerebral ventricular system of the brain as a result of a primary cause. This disease can be acquired or congenital, pronouncing itself with clinical signs of neurological disease. This article presents a clinical case with a detailed description of the physiopathology, diagnosis and surgical treatment of hydrocephalus in a canine patient that was attended at the Centro de Medicina Veterinaria y Zootecnia CES (Medellín, Colombia). In this patient a ventricle to peritoneal derivation was practiced as a surgical treatment of the disease; the surgery was carried out without complications and a satisfactory recovery with progressive reversion of the clinical symptomatology was obtained. The ventricle to peritoneal derivation is a surgical option for the treatment of hydrocephalus in canine that becomes a valuable tool for veterinarians, which allows them to establish a more hopeful prognosis regarding longevity and quality of life of the patient.La hidrocefalia es una acumulación excesiva de liquido cefalorraquídeo (LCR) en el sistema ventricular cerebral como consecuencia de una causa primaria. Esta enfermedad puede ser adquirida o congénita, manifestándose con signos clínicos de enfermedad neurológica. Este artículo presenta una revisión sobre la fisiopatología, diagnóstico y tratamiento médico quirúrgico de la hidrocefalia en un paciente canino atendido en el Centro de Medicina Veterinaria y de Zootecnia del CES (Medellín, Colombia). En el paciente se realizó una derivación ventrículo peritoneal como tratamiento quirúrgico de la enfermedad; la cirugía se llevó a cabo sin complicaciones y se obtuvo una recuperación satisfactoria con reversión progresiva de la sintomatología clínica. La derivación ventrículo peritoneal como opción quirúrgica para el tratamiento de la hidrocefalia en caninos se convierte entonces en una herramienta valiosa para el médico veterinario, la cual le permite establecer un pronóstico más esperanzador respecto a la longevidad y calidad de vida del paciente

Protective effect of melatonin on myocardial infarction

The dose- and time dependence of melatonin and the effective window of melatonin administration were determined in a mouse model of myocardial infarction. When mouse hearts were subjected to 60 min of occlusion of the left anterior descending artery (LAD) followed by 4 h of reperfusion, melatonin pretreatment for 30 min significantly reduced the infarct size/risk area. The most effective dose was found to be 150 μg/kg intraperitoneally, and the effective period of protection lasted up to 2 h after melatonin administration. Melatonin administration 45 min after LAD ligation or right before reperfusion was as effective as administration 30 min before ligation; however, melatonin administered after the release of occlusion was not protective. Melatonin\u27s effect was still present in mice deficient for the Mel1a melatonin receptor. 8-Methoxy-2-propionamidotetralin, a melatonin receptor agonist with no antioxidant activity, offered no protection, suggesting a lack of involvement of melatonin receptors. Finally, the effects of melatonin were similar in rats and mice. Our results demonstrate that melatonin is an effective cardioprotective agent when administered either before or during coronary occlusion at a very low dose