Automated system for surface photovoltage spectroscopy.

This paper details the development of a lab-made experimental setup for surface photovoltage spectroscopy (SPS) measurements using an open-source and Arduino® microcontroller to control a monochromator and some off-the-shelf electronic components. The experimental setup is interfaced to a computer, where LabVIEW® based software manages system control and data acquisition. We also report the design of a compact sample holder, simple and easy to manufacture and handle. Results of the application of SPS to the characterization of MoO3 thin films and semiconductor laser structures are presented to validate the performance of the setup, highlighting the effectiveness of SPS for the characterization of semiconductor materials and devices.

Differences in resource use lead to coexistence of seed-transmitted microbial populations.

Seeds are involved in the vertical transmission of microorganisms in plants and act as reservoirs for the plant microbiome. They could serve as carriers of pathogens, making the study of microbial interactions on seeds important in the emergence of plant diseases. We studied the influence of biological disturbances caused by seed transmission of two phytopathogenic agents, Alternaria brassicicola Abra43 (Abra43) and Xanthomonas campestris pv. campestris 8004 (Xcc8004), on the structure and function of radish seed microbial assemblages, as well as the nutritional overlap between Xcc8004 and the seed microbiome, to find seed microbial residents capable of outcompeting this pathogen. According to taxonomic and functional inference performed on metagenomics reads, no shift in structure and function of the seed microbiome was observed following Abra43 and Xcc8004 transmission. This lack of impact derives from a limited overlap in nutritional resources between Xcc8004 and the major bacterial populations of radish seeds. However, two native seed-associated bacterial strains belonging to Stenotrophomonas rhizophila displayed a high overlap with Xcc8004 regarding the use of resources; they might therefore limit its transmission. The strategy we used may serve as a foundation for the selection of seed indigenous bacterial strains that could limit seed transmission of pathogens.

Comparación entre el sistema Phoenix y métodos basados en agar para el ensayo de sensibilidad a antibióticos en Streptococcus spp / Comparison between Phoenix system and agar-based methods for antimicrobial susceptibility testing of Streptococcus spp

Introducción. La resistencia a los antibióticos en el grupode los estreptococos es un problema emergente de especialimportancia en las infecciones graves. El sistema automatizadoBD Phoenix para identificación y antibiograma esun instrumento diagnóstico recientemente disponible quepermite obtener resultados en 12 h.Métodos. Se ha llevado a cabo un estudio comparativoentre el sistema BD Phoenix con paneles SMIC/ID-9 y el métododisco-difusión para la realización de estudios de sensibilidada antibióticos. Se utilizaron 200 aislamientos clínicosde estreptococos: betahemolíticos (n=65), viridans (n=87) yStreptococcus pneumoniae (n=48).Resultados. De forma global, en relación con el métododisco-difusión, hubo un acuerdo entre categorías superioral 96,7% (94,8% en betahemolíticos y 97,9% en viridans).Las tasas de errores menores fueron inferiores al 10% paratodos los antibióticos. El mayor porcentaje de errores gravescorrespondió a eritromicina y clindamicina dentro del grupode los betahemolíticos (14,7 %). El porcentaje global deerrores muy graves fue inferior al 0,5%. Los resultados parapenicilina en estreptococos viridans y S. pneumoniae presentaronun acuerdo entre categorías del 89,7 y 91,7% frentea Etest, respectivamente.Conclusiones. El sistema automatizado BD Phoenix esun instrumento diagnóstico de gran utilidad y efectividadpara el ensayo cuantitativo de la sensibilidad a los antibióticosen el grupo de los estreptococos (AU)

Introduction. Antibiotic resistance is an emergingproblem among streptococcal species, especially for severeinfections. Automated diagnostic systems for antimicrobialsusceptibility testing, such as BD Phoenix, is arecently available instruments that makes it possible toobtain results within 12 h.Methods. Antimicrobial susceptibility testing resultsof the BD Phoenix system were compared to those obtainedfrom Clinical Laboratory Standards Institute (CLSI)disk-diffusion method. Two-hundred different clinicalisolates of streptococci were assayed: beta-hemolytic(n=65), viridans (n=87), S. penumoniae (n=48).Results. Overall, there was categorical agreement greaterthan 96.7% (94.8% for beta-hemolytic and 97.9% for viridansgroup) in relationship to the disk-diffusion method.The minor error rates were less than 10% for all the antibiotics.The greatest percentage of serious errors correspondedto erythromycin and clindamycin within the beta-hemolyticgroup (14.7%). Overall percentage of very serious errors wasless 0.5%. The results for penicillin in viridans streptococciand S. pneumoniae results showed 89.7% and 91.7% of categoricalagreement, respectively, using the Etest as reference.Conclusions. The automated BD Phoenix system is avery useful and effective diagnostic tool for quantitativetesting of sensitivity to antibiotics in the streptococci group (AU)

Bacteriemia por Flavimonas oryzihabitans en un paciente no neutropénico con enfermedad cardiaca / Flavimonas oryzihabitans bacteriemia in a non-neutropenic patient with cardiac illness

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Excess prevalence of fasting and postmethionine-loading hyperhomocysteinemia in stable renal transplant recipients.

Hyperhomocysteinemia, either fasting or after methionine loading, may contribute to the increased incidence of cardiovascular disease events experienced by renal transplant recipients. Limited data are available on fasting homocysteine (Hcy) levels, and none on postmethionine-loading Hcy levels, in these patients. We assessed the prevalence and potential determinants of fasting and postmethionine-loading hyperhomocysteinemia in 29 stable renal transplant recipients and 58 age- and sex-matched, population-based controls free of renal disease with serum creatinine levels of 1.5 mg/dL or less. Total (t) plasma Hcy was determined fasting and 2 hours after methionine loading, along with fasting determinations of the B-vitamin cofactors/substrates for Hcy metabolism, ie, pyridoxal 5'-phosphate, B-12, and folate and serum creatinine. Geometric mean fasting (18.1 versus 9.8 microM, P < .001) and postmethionine-loading increase (22.0 versus 15.2, P = .001) in tHcy levels were significantly greater in the renal transplant recipients, as were the prevalence odds (with 95% confidence intervals) for fasting [14.8 (3.4-64.7)], postmethionine loading [6.9 (1.5-32.8)], combined fasting and postmethionine-loading [18.0 (2.3-142.1)] hyperhomocysteinemia, and inadequate circulating folate [4.2 (1.1-16.5)] or pyridoxal 5'-phosphate [3.2 (0.9-11.0) status. Correlation analyses suggested important potential relationships between creatinine and both fasting (+0.64, P < .001) and postmethionine-load increase (+0.38, P = .045) in tHcy, folate and fasting (-0.41, P = .025) tHcy, and pyridoxal 5'-phosphate and postmethionine-loading increase (-0.33, P = .091) in tHcy. We conclude that there is an excess prevalence of fasting and postmethionine-loading hyperhomocysteinemia in stable renal transplant recipients. Renal function is related to both fasting and postmethionine loading-hyperhomocysteinemia, inadequate folate status is associated with fasting hyperhomocysteinemia, and inadequate vitamin B-6 status may be related to postmethionine-loading hyperhomocysteinemia in this patient population.

Generalized electrical analysis of low-pass and high-pass birdcage resonators.

The radio-frequency 'birdcage resonator' has found wide use in MRI/MRS for its field homogeneity and signal-noise characteristics. This paper presents a general analysis, derived from lumped element transmission line theory, of the electrical behavior of unloaded, N-column birdcage resonators applicable to several versions of the basic design including low-pass and high-pass coils. Analytic expressions and computer results are presented for both types of coil describing resonant frequencies, input and characteristic impedances, dispersion relations, pass-bands, resonant peak bandwidth and Q. Theoretical expressions for normalized resonant frequency difference ratios independent of element values and resonator geometry have been developed for generic low- and high-pass coils. Experimental measurements of resonant frequencies were made for six coils, and the average agreement with theoretical predictions was approximately 4%.