Adaptive Parameters for LoRa-Based Networks Physical-Layer.

Sub-GHz communication provides long-range coverage with low power consumption and reduced deployment cost. LoRa (Long-Range) has emerged, among existing LPWAN (Low Power Wide Area Networks) technologies, as a promising physical layer alternative to provide ubiquitous connectivity to outdoor IoT devices. LoRa modulation technology supports adapting transmissions based on parameters such as carrier frequency, channel bandwidth, spreading factor, and code rate. In this paper, we propose SlidingChange, a novel cognitive mechanism to support the dynamic analysis and adjustment of LoRa network performance parameters. The proposed mechanism uses a sliding window to smooth out short-term variations and reduce unnecessary network re-configurations. To validate our proposal, we conducted an experimental study to evaluate the performance concerning the Signal-to-Noise Ratio (SNR) parameter of our SlidingChange against InstantChange, an intuitive mechanism that considers immediate performance measurements (parameters) for re-configuring the network. The SlidingChange is compared with LR-ADR too, a state-of-the-art-related technique based on simple linear regression. The experimental results obtained from a testbed scenario demonstrated that the InstanChange mechanism improved the SNR by 4.6%. When using the SlidingChange mechanism, the SNR was around 37%, while the network reconfiguration rate was reduced by approximately 16%.

Energy Consumption Evaluation of a Routing Protocol for Low-Power and Lossy Networks in Mesh Scenarios for Precision Agriculture.

Sensor nodes are small, low-cost electronic devices that can self-organize into low-power networks and are susceptible to data packet loss, having computational and energy limitations. These devices expand the possibilities in many areas, like agriculture and urban spaces. In this work, we consider an IoT environment for monitoring a coffee plantation in precision agriculture. We investigate the energy consumption under low-power and lossy networks considering three different network topologies and an Internet Engineering Task Force (IETF) standardized Low-power and Lossy Network (LLN) routing protocol, the Routing Protocol for LLNs (RPL). For RPL, each secondary node selects a better parent according to some Objective Functions (OFs). We conducted simulations using Contiki Cooja 3.0, where we considered the Expected Transmission Count (ETX) and hop-count metric (HOP) metrics to evaluate energy consumption for three distinct topologies: tree, circular, and grid. The simulation results show that the circular topology had the best (lowest) energy consumption, being 15% better than the grid topology and 30% against the tree topology. The results help the need to improve the evolution of RPL metrics and motivate the network management of the topology.

Comparative in vitro study of the antimicrobial activities of different commercial antibiotic products of vancomycin.

BACKGROUND: One of the most critical problems about antimicrobial therapy is the increasing resistance to antibiotics. Previous studies have shown that there is a direct relation between erroneous prescription, dosage, route, duration of the therapy and the antibiotics resistance. Other important point is the uncertainty about the quality of the prescribed medicines. Some physicians believe that generic drugs are not as effective as innovator ones, so it is very important to have evidence that shows that all commercialized drugs are suitable for therapeutic use. METHODS: Microbial assays were used to establish the potency, the Minimal Inhibitory Concentrations (MICs), the Minimal Bactericidal Concentration (MBCs), the critical concentrations, and the production of spontaneous mutants that are resistant to vancomycin. RESULTS: The microbial assay was validated in order to determine the Vancomycin potency of the tasted samples. All the products showed that have potency values between 90 - 115% (USP requirement). The products behave similarly because the MICs, The MBCs, the critical concentrations, the critical concentrations ratios between standard and samples, and the production of spontaneous mutants don't have significant differences. CONCLUSIONS: All products analyzed by microbiological tests, show that both trademarks and generics do not have statistical variability and the answer of antimicrobial activity Show also that they are pharmaceutical equivalents.

Pharmacokinetics and Pharmacodynamics of Cefepime in Adults with Hematological Malignancies and Febrile Neutropenia after Chemotherapy.

Patients with chemotherapy-induced febrile neutropenia (CIFN) may have changes in the pharmacokinetics (PK) compared to patients without malignancies or neutropenia. Those changes in antibiotic PK could lead to negative outcomes for patients if the therapy is not adequately adjusted to this. In this, open-label, non-randomized, prospective, observational, and descriptive study, a PK model of cefepime was developed for patients with hematological neoplasms and post-chemotherapy febrile neutropenia. This study was conducted at a cancer referral center, and study participants were receiving 2 g IV doses of cefepime every 8 h as 30-min infusions. Cefepime PK was well described by a two compartment model with a clearance dependent on a serum creatinine level. Using Monte Carlo simulations, it was shown that continuous infusions of 6g q24h could have a good achievement of PK/PD targets for MIC levels below the resistance cut-off point of Enterobacteriaceae. According to the simulations, it is unnecessary to increase the daily dose of cefepime (above 6 g daily) to increase the probability of target attainment (PTA). Cumulative fraction of response (CFR) using interment dosing was suboptimal for empirical therapy regimens against K. pneumoniae and P. aeruginosa, and continuous infusions could be used in this setting to maximize exposure. Patients with high serum creatinine levels were more likely to achieve predefined PK/PD targets than patients with low levels.

Comparative in vitro study of the antimicrobial activities of different commercial antibiotic products for intravenous administration.

BACKGROUND: The antimicrobial resistance is a global problem, probably due to the indiscriminate and irrational use of antibiotics, prescriptions for incorrect medicines or incorrect determinations of dose, route and/or duration. Another consideration is the uncertainty of patients receiving antibiotics about whether the quality of a generic medicine is equal to, greater than or less than its equivalent brand-name drug. The antibiotics behaviors must be evaluated in vitro and in vivo in order to confirm their suitability for therapeutic use. METHODS: The antimicrobial activities of Meropenem and Piperacillin/Tazobactam were studied by microbiological assays to determine their potencies (content), minimal inhibitory concentrations (MICs), critical concentrations and capacity to produce spontaneous drug-resistant mutants. RESULTS: With respect to potency (content) all the products fulfill USP requirements, so they should all be considered pharmaceutical equivalents. The MIC values of the samples evaluated (trade marks and generics) were the same for each strain tested, indicating that all products behaved similarly. The critical concentration values were very similar for all samples, and the ratios between the critical concentration of the standard and those of each sample were similar to the ratios of their specific antibiotic contents. Overall, therefore, the results showed no significant differences among samples. Finally, the production of spontaneous mutants did not differ significantly among the samples evaluated. CONCLUSIONS: All the samples are pharmaceutical equivalents and the products can be used in antimicrobial therapy.

Pharmacokinetics of piperacillin/tazobactam in cancer patients with hematological malignancies and febrile neutropenia after chemotherapy.

INTRODUCTION: Patients with febrile neutropenia (FN) exhibit changes in extracellular fluid that may alter the plasma concentrations of beta-lactams and result in therapeutic failure or toxicity. We evaluated the pharmacokinetics of piperacillin/tazobactam in patients with hematological malignancies and FN after receiving chemotherapy at a primary public cancer center. METHODS: This was an open, nonrandomized, observational, descriptive, and prospective study. Samples from 15 patients with hematological malignancies and FN were evaluated after the administration of chemotherapy. Five blood samples were taken from each patient when the antibiotic level was at steady-state 10, 60, 120, 180, and 350 min after each dose. Antibiotic concentrations were measured using gel diffusion with Bacillus subtilis. All study participants provided written informed consent. RESULTS: We investigated the pharmacokinetics of piperacillin in 14 patients between the ages of 18 years and 59 years and with a mean absolute neutrophil count of 208 cells per mm³ (standard deviation (SD) ± 603.2). The following pharmacokinetic measurements were obtained: maximum concentration, 94.1-1133 mg/L; minimum concentration, 0.47-37.65 mg/L; volume of distribution, 0.08-0.65 L/kg (mean, 0.34 L/kg); drug clearance (CL), 4.42-27.25 L/h (mean, 9.93 L/h); half-life (t(1/2)), 0.55-2.65 h (mean, 1.38 h); and area under the curve, 115.12-827.16 mg · h/L. CONCLUSION: Patients with FN after receiving chemotherapy exhibited significant variations in the pharmacokinetic parameters of piperacillin compared with healthy individuals; specifically, FN patients demonstrated an increase in t1(/2) and decreased CL.

Biodesulfurización de queroseno con células inmovilizadas de Pseudomonas sp. No. 6 (aislado nativo) en un novedoso biorreactor de lecho de tubos con recirculación / Kerosene biodesulfurization by immobilized cells Pseudomonas sp. No. 6 (native isolated) at a new bioreactor of pipe bed with recirculation

En este trabajo se realizó la biodesulfurización de keroseno con células inmovilizadas de Pseudomonas spp. ATCC 39327, en un sistema emulsionado, W/O 30/70 (v/v), con Medio Mínimo de Sales (MMS) como fase dispersa. El sistema de inmovilización consta de dos paneles de 60 tubos cada uno. Los tubos de alta alúmina, tienen 140 mm de largo, 6.6 mm diámetro externo y 3.2 mm de diámetro interno, con una porosidad del 43 porciento y capacidad de retención de 9,5*109 células/g de soporte, colocados dentro de una columna de vidrio enchaquetada, de 80 por 400 mm de zona de reacción, conectada a un tanque de recirculación, y el fluido se mueve con aire a razón de 8.8 pies3/h. Después de 120 horas de proceso a 30 ºC y presión atmosférica se obtuvo una remoción del contenido de azufre de 43 porciento y una pérdida calórica menor del 2 porciento

Producción de fructooligosacaridos (FOS) por tecnología de enzimas. Parte I: Evaluación de aislados nativos de hongos para la producción de FOS / Production of fructooligosaccharides (FOS) by enzymatic technology. Part I: Evaluation of native isolates obtained from fungi for production of FOS

En este trabajo se estudió la influencia de la concentración de sacarosa, extracto de levadura y carbonato de calcio en la producción de FOS y la actividad fructosiltransferasa (FTF) en fermentaciones de 24, 36 y 48 horas usando Aspergillus niger AN166 como modelo biológico. La actividad FTF más alta de A. niger fue obtenida con 20 por ciento de sacarosa y 0.2 por ciento de extracto de levadura. El carbonato de calcio no tiene un efecto significativo en la producción de FOS. Adicionalmente, el medio de cultivo derivado del trabajo anterior fue usado para el aislamiento de hongos nativos de diferentes regiones de Cundinamarca (Colombia). Los aislados fueron evaluados con relación a la producción de FOS y actividad FTF. Solamente cinco aislados mostraron una mayor producción de FOS y actividad FTF que el A. niger AN166

Estudio comparativo de la actividad antimicrobiana de diferentes presentaciones comerciales de antibióticos de administración intravenosa a través de métodos in vitro / Comparative study of the antimicrobial activity of several marketed antibiotic drugs for intravenous administration by in vitro methods

En este trabajo, se desarrollaron bioensayos para la valoración de ceftriaxona, cefotaxima, ceftazidima, ampicilina/sulbactam e imipenem/cilastatina. Se pudo establecer un único microorganismo (esporas de Bacillus subtilis ATCC 6633) para la ejecución del bioensayo. El rango de concentración que tiene la mejor correlación dosis-respuesta es propio de cada antibiótico, al igual que las condiciones del ensayo (pH de la solución de antibiótico, pH de medio de cultivo, tiempo de incubación). Con los bioensayos validados se hizo un estudio de comparación de muestras de productos innovadores, genéricos de marca y genéricos, que dio como resultado que presentan la misma actividad antimicrobiana in vitro, además de confirmar que son equivalentes farmacéuticos

Obtención de mutantes espontáneas de Clostridium acetobutylicum resistentes al butanol / Obtention of spontaneous mutant of Clostridium acetobutylicum of butanol resistant

En este trabajo reporta la obtención de mutantes espontáneas de Clostridium acetobutylicum DSM1732 resistente a altas concentraciones de butanol (25 g/l), que produce 29.41 g/l de solventes totales, con un rendimiento de sustrato en solventes (Ypis) de 0.59 g de solventes totales por g de sustrato consumido y una productividad de 0.196 g de sol. tot./L*h en medio de cultivo "industrial" a base de melaza. El mutante denominado Clostridium acetobutylicum DSM11732 R se obtuvo mediante exposición a concentraciones crecientes de butanol. También se demostró que en realidad es un grupo de mutantes resistentes al butanol que producen diferentes niveles de solventes totales. El grupo esta conformado por nueve mutantes denominados Clostridium acetobutylicum IBUN I, II, III, IV, V, VI, VII, VII y IX las cuales fueron evaluadas en el medio "industrial" a base de melaza. Las mutantes individualmente producen entre 6 y 18 g/l de solventes totales, con rendimientos (Ypis) entre 0,2 y 0,5 y productividades entre 0.09 y 0.27g de solv. tot./l*h. El estudio de los diferentes parámetros de la fermentación acetobutílica desarrollada por los nueve mutantes se ajusta al mdelo de la fermentación acetobutílica (ABE) en relación al consumo de sustrato, la reasimilación de los ácidos, la velocidad específica de crecimiento (µ) y la producción de solventes...

Evaluación de cepas de clostridium acetobutylicum para el desarrollo de la fermentación acetobutílica / Evaluation of strains of Clostridium acetobutylicum for the development of acetobutylic fermentation

En este trabajo se hizo la evaluación de tres cepas de Clostridium acetobutylicum (DSM 1732, DSM 792 y ATCC 824) para la fermentación acetobutílica (ABE). De las tres, la cepa de Clostridium acetobutylicum DSM 1732 fue la cepa seleccionada por que produce la mayor cantidad de solventes totales (8.9 g/L), el mayor rendimiento (Yp/s 0.173) y la mayor productividad (0.205 g de solventes totales /L h). Luego con la cepa seleccionada se evaluó el efecto de la melaza sobre la fermentación ABE dando como resultado que con este sustrato se obtiene mayor concentración de solventes totales (12.30 g/L) y mayor productividad (0.205 g de solventes totales/L h)