Resistance measurements and vortex fluctuations in two-dimensional superconducting films

Recently theories of vortex fluctuations in two-dimensional superconducting films have been compared to the experimentally determined power law dependence of voltage on current and to the temperature-dependent resistance in small applied fields. Here an alternative interpretation of the power law and a practical difficulty of flux pinning for measurements in small fields are pointed out. To illustrate these points, experimental examples are presented for very homogeneous granular aluminum films.     

The morphology of MoS2, WS2, Co–Mo–S, Ni–Mo–S and Ni–W–S nanoclusters in hydrodesulfurization catalysts revealed by HAADF-STEM

HAADF-STEM studies have provided detailed morphological insight regarding MoS₂, WS₂, Co–Mo–S, Ni–Mo–S and Ni–W–S nanostructures in graphite-supported catalysts. It is found that the technique allows the catalytically active edges to be imaged even for single layer metal sulfide structures. Unpromoted MoS₂ and WS₂ are predominantly present as slightly truncated triangular clusters containing only a single S–M–S layer (M = Mo, W). The addition of promoter atoms results in more heavy truncations consistent with the expected tendency for the Co–Mo–S structures to expose promoted S-type edges at the expense of unpromoted Mo-type edges. However, the HAADF-STEM (High-Angle Annular Dark-field Scanning Transmission Electron Microscopy) results show for the first time that Co–Mo–S and Ni–W–S may also expose extended high index truncations.     

Antigen detection on resin sections and methods for improving the immunogold labeling by manipulating the resin

Considering the importance of immunolocalization of cellular substances combined with good ultrastructure and ease of use, this review is focused on the use of resin and the possibilities of manipulating the resin before and after embedding in order to improve the immunolabeling of resin sections for electron microscopy. The qualities of acrylic resins and conventional epoxy resin for immunoelectron microscopy are discussed. Acrylic sections are usually more suited for immunoelectron microscopy than conventional epoxy sections. Different etching procedures (sodium ethoxide or sodium metaperiodate) may be applied to conventional epoxy sections to enhance the yield of immunolabeling. Lately, a method which does not involve any kind of etching has been developed for enhancing the immunogold labeling of epoxy sections up to about 8 times. This method involves increased concentration of accelerator in the epoxy resin mixture when processing the tissue. The ultrastructural preservation of the tissue is important in immunoelectron microscopical procedures, and not only the intensity of the immunolabeling; in this respect no resin may compete with the widely used epoxy resins.     

Liposuction reduces arm lymphedema without significantly altering the already impaired lymph transport

In a prospective study, 20 patients with arm lymphedema after breast cancer treatment underwent liposuction combined with Controlled Compression Therapy (CCT) or CCT alone. Indirect lymphoscintigraphy (ILS) was used to study lymph kinetics before and after intervention. Lymphoscintigrams from the contralateral, non-edematous arm were characterized by prompt transit of the radiotracer (99mTc-albumin nanocolloid) to the axillary nodes, whereas tracer accumulation as dermal backflow characterized tracer transport in the lymphedematous arm. Neither liposuction with CCT nor CCT alone, changed this ILS profile. Liposuction combined with CCT reduced arm edema volume by (median) 115% (range 92-179%), whereas CCT alone decreased arm edema volume by only 54% (range 7-81%) (p = 0.008). Because liposuction in conjunction with CCT was not associated with further impairment to an already restricted lymph transport, we recommend this therapy (liposuction with external compression) for chronic arm lymphedema, as it reduces edema volume safely, rapidly, and more efficiently than external compression alone. Moreover, it does not worsen an already impaired lymph transport in the lymphedematous upper extremity.     

In vitro conversion of Borrelia burgdorferi to cystic forms in spinal fluid, and transformation to mobile spirochetes by incubation in BSK-H medium

An opportunist infection (OI) is understood to be an infection produced by microorganisms that invade a host with impaired immune capacity, such as children with HIV infection. The adequate treatment and chemoprophylaxis of these infections has improved the prognosis of their evolution, although they still present a high morbidity and mortality when they occur. In this sense, the introduction of triple therapy (new antiretroviral inhibitors and protease inhibitors) is likely to produce a prompt decrease in the incidence of OI because of the regression in the degree of immunosuppression that it induces. The degree of immunosuppression is determined by the number of CD4 lymphocytes, the most reliable marker for assessment. Normal CD4 lymphocytes values are different for each age group and have important connotations for the prophylactic measures to be used at each moment depending on the CD4 lymphocyte count. Opportunist infections influence the quality of life of patients. More than 100 microorganisms, including bacteria, viruses, fungi and protozoa, cause OI. This paper describes primary and secondary prophylaxis as well as the treatment of the most frequent opportunist infections (Pneumocystis carinii pneumonia, bacterial infections, Cryptococcus neoformans, Cytomegalovirus, Herpes simple, Varicella-zoster virus. Toxoplasmosis, Mycobacterium tuberculosis, M. avium-intracellulare, M. kansasii).     

What is the confocal parameter?

A novel derivation is presented of the Gaussian beam as a limit of the solution to the full wave equation. Usually, the functional form of the Gaussian beam is found by a two-step process. First, the Green's function of the paraxial wave equation is identified. Then, since the paraxial wave equation is invariant under translation, the z-axis variable is replaced by z+jb. It is shown that when starting with a solution of the full three-dimensional Helmholtz equation in spherical coordinates, performing the transformation z→z+jb corresponds physically to causing the phase fronts of the solution to become ellipsoids. The separation of the foci of the ellipsoids is 2b, where b is the confocal parameter of the beam. In the paraxial limit the ellipsoidal solution becomes a Gaussian beam. Adopting this approach to Gaussian beams allows a simple, geometrical interpretation of the optical resonator stability criterion     

Real time monitoring of bioreactor mAb IgG3 cell culture process dynamics via Fourier transform infrared spectroscopy: Implications for enabling cell culture process analytical technologyŽ 

Compared to small molecule process analytical technology (PAT) applications, biotechnology product PAT applications have certain unique challenges and opportunities. Understanding process dynamics of bioreactor cell culture process is essential to establish an appropriate process control strategy for biotechnology product PAT applications. Inline spectroscopic techniques for real time monitoring of bioreactor cell culture process have the distinct potential to develop PAT approaches in manufacturing biotechnology drug products. However, the use of inline Fourier transform infrared (FTIR) spectroscopic techniques for bioreactor cell culture process monitoring has not been reported. In this work, real time inline FTIR Spectroscopy was applied to a lab scale bioreactor mAb IgG3 cell culture fluid biomolecular dynamic model. The technical feasibility of using FTIR Spectroscopy for real time tracking and monitoring four key cell culture metabolites (including glucose, glutamine, lactate, and ammonia) and protein yield at increasing levels of complexity (simple binary system, fully formulated media, actual bioreactor cell culture process) was evaluated via a stepwise approach. The FTIR fingerprints of the key metabolites were identified. The multivariate partial least squares (PLS) calibration models were established to correlate the process FTIR spectra with the concentrations of key metabolites and protein yield of in-process samples, either individually for each metabolite and protein or globally for all four metabolites simultaneously. Applying the 2^nd derivative pre-processing algorithm to the FTIR spectra helps to reduce the number of PLS latent variables needed significantly and thus simplify the interpretation of the PLS models. The validated PLS models show promise in predicting the concentration profiles of glucose, glutamine, lactate, and ammonia and protein yield over the course of the bioreactor cell culture process. Therefore, this work demonstrated the technical feasibility of real time monitoring of the bioreactor cell culture process via FTIR spectroscopy. Its implications for enabling cell culture PAT were discussed.     

Characterization of wavelength chirping in modelocked monolithicCPM lasers

A new method to measure the chirp of pulses emitted from repetitively driven lasers is described. The technique relies on spectrally filtering the output of the laser, detecting it, and then measuring its phase with respect to a reference signal via a mixing technique. We demonstrate the method by measuring the chirp of pulses emitted from monolithic CPM lasers. The measured chirp agrees with that predicted by a newly developed model of the CPM lasers     

Disrupted [Ca2+]i homeostasis contributes to the toxicity of nitric oxide in cultured hippocampal neurons

Nitric oxide (NO) has been shown to be an important mediator in several forms of neurotoxicity. We previously reported that NO alters intracellular Ca2+ concentration ([Ca2+]i) homeostasis in cultured hippocampal neurons during 20-min exposures. In this study, we examine the relationship between late alterations of [Ca2+]i homeostasis and the delayed toxicity produced by NO. The NO-releasing agent S-nitrosocysteine (SNOC; 300 microM) reduced survival by about one half 1 day after 20-min exposures, as did other NO-releasing agents. SNOC also was found to produce prolonged elevations of [Ca2+]i, persisting at 2 and 6 h. Hemoglobin, a scavenger of NO, blocked both the late [Ca2+]i elevation and the delayed toxicity of SNOC. Removal of extracellular Ca2+ during the 20-min SNOC treatment failed to prevent the late [Ca2+]i elevations and did not prevent the delayed toxicity, but removal of extracellular Ca2+ for the 6 h after exposure as well blocked most of the toxicity. Western blots showed that SNOC exposure resulted in an increased proteolytic breakdown of the structural protein spectrin, generating a fragment with immunoreactivity suggesting activity of the Ca2+-activated protease calpain. The spectrin breakdown and the toxicity of SNOC were inhibited by treatment with calpain antagonists. We conclude that exposures to toxic levels of NO cause prolonged disruption of [Ca2+]i homeostatic mechanisms, and that the resulting persistent [Ca2+]i elevations contribute to the delayed neurotoxicity of NO.