On the quantization of the electromagnetic field in conducting media

In this work we investigate the quantization of electromagnetic waves propagating through homogeneous conducting linear media with no charge density. We use Coulomb's gauge to reduce the problem to that of a time-dependent harmonic oscillator, which is described by the Caldirola–Kanai Hamiltonian. Furthermore, we obtain the corresponding exact wave functions with the help of quadratic invariants and of the dynamic invariant method. These wave functions are written in terms of a particular solution of the Milne–Pinney equation. We also construct coherent and squeezed states for the quantized electromagnetic waves and evaluate the quantum fluctuations in coordinates and momentum as well as the uncertainty product for each mode of the electromagnetic field.     

Towards an autonomous fall detection and alerting system on a mobile and pervasive environment

In recent years, the use of sensors on mobile devices is highly desirable. In particular, an accelerometer can be used for numerous applications such as tracking object or monitoring of the elderly. This paper presents an application tool based on an accelerometer, call SensorFall to detect and report the acceleration caused by a fall, which allows sending alerts in the form of SMS, phone call, or by location using the GPS. We have implemented and verified the SensorFall in various environments, such as a hospital or a normal daily life for the elderly, also implemented the system calibration in order to adapt better the living conditions of each person. The results show that it performs well.     

Effects of a Westernized Diet on the Reflexes and Physical Maturation of Male Rat Offspring During the Perinatal Period

This study evaluates the effects of a westernized diet during the perinatal period on the maternal performance and growth and development of rat offspring. Female Wistar rats were fed with either a control (C) diet, with casein as the protein source or a westernized (W) diet, during pregnancy and lactation. The pups were divided, eight per group, into the same diet groups as their dams. During lactation, the body weight (day 1, W = 6.85 ± 0.62 g, C = 5.81 ± 0.49, p < 0.05; day 21, W = 55.42 ± 3.78, C = 47.75 ± 3.45, p < 0.001) and somatic growth (body length day 1, W = 53.24 ± 2.16, C = 50.641 ± 1.79, p < 0.05; day 21, W = 124.8, C = 119.903 ± 3.71, p < 0.001) in the male offspring showed significant differences among the groups. The physical appearance and reflex maturation showed differences between day 1 and day 3. With the westernized diet, during the perinatal period, no alterations in maternal weight gain, gestation or performance were observed; however, changes in the coefficients of feed efficiency and energy during lactation were noted. Besides, blood glucose was found to be elevated at the end of lactation (C = 3.67 ± 0.35 mmol/l, W = 5.2 0 ± 0.49 mmol/l). At 21 days, the male pups from the dams on the westernized diet were 15 % heavier, and the maturation of the neural reflexes and physical characteristics were found to occur earlier. Therefore, the consumption of a westernized diet during the perinatal period was independent of maternal energy intake, and influenced the growth and development of offspring.     

Force Curve Measurements with the AFM: Application to the In Situ Determination of Grafted Silicon-Wafer Surface Energies

The atomic force microscope (AFM) can be used to perform surface force measurements in the quasi-static mode (cantilever is not oscillating) to investigate nanoscale surface properties. Nevertheless, there is still a lack of literature proposing a complete systematic and rigorous experimental procedure that enables one to obtain reproducible and significant quantitative data. This article focuses on the fundamental experimental difficulties arising when making force curve measurements with the AFM in air. On the basis of this AFM calibration procedure, quantitative assessment values were used to determine, in situ, SAM (or Self Assembled Monolayer)-tip thermodynamic work of adhesion at a local scale, which have been found to be in good agreement with quoted values. Finally, determination of surface energies of functionalised silicon wafers (as received, CH₃, OH functionalised silicon wafers) with the AFM (at a local scale) is also proposed and compared with the values obtained by wettability (at a macroscopic scale). In particular, the effect of the capillary forces is discussed.     

Structural Investigation of the Surface of Bioglass 45S5 Enriched with Calcium Ions

In this article the changes on the surface of the 45S5 bioglass submitted to an enrichment with calcium ions were investigated. The method employed was the immersion of bioglass in calcium molten salt bath at 450°C. Changes in composition were probed by different techniques of chemical analysis. The use of SEM‐EDS allowed estimating the thickness modified, as being about 10 μm. X‐ray photoelectron spectroscopy enabled to infer over the structural changes on the surface of 45S5 bioactive glass. The entry of calcium in the vitreous network promoted the phase separation of microdomains rich in silica and phosphate on the surface of the glass. The formation of immiscibility region was attributed a depolymerization of silica network and also, to a possible migration of phosphate species from the bulk. The results of this study indicate a great change in the surface properties of this biomaterial. In addition, the method proposed in this study proved to be very promising in the possibility of designing the surface of bioactive glasses, to modulate the desired properties, keeping the bulk unchanged.     

Determination of Sugarcane Bagasse Lignin S/G/H Ratio by Pyrolysis GC/MS

Abstract

In this work, analytical pyrolysis (Py-GC-MS) was employed to identify lignin markers derived from H, S, and G phenylpropanoid units in sugarcane bagasse. Temperatures of 450 and 500°C allowed the detection of key products that were informative on the bagasse lignin composition. The method was validated by comparing the S/G ratio as determined by the nitrobenzene oxidation (NBO) standard method for five sugarcane varieties. The S/G ratio as determined by Py-GC-MS, taking into consideration all known lignin markers in the analysis, resulted in a correlation coefficient of 0.85 with a linear regression coefficient of 0.74. When a group of selected markers (M2) was used, the correlation coefficient between methods was improved to 0.95 and the linear regression coefficient was adjusted to 0.92. M2 markers consisted of five syringyl markers (syringol, 4-methylsyringol, 4-ethylsyringol, 4-vinylsyringol, and trans-4-propenylsyringol) and four guaiacyl markers (guaiacol, 4-vinylguaiacol, 4-methylguaiacol, and vanillin). Importantly, Py-GC-MS allowed for the study of lignin composition in sugarcane bagasse without the need to remove the extractives, minimizing the work with sample preparations.     

Freshwater Plants Synthesize Sulfated Polysaccharides: Heterogalactans from Water Hyacinth (Eicchornia crassipes)

Sulfated polysaccharides (SP) are found mainly in seaweeds and animals. To date, they have only been found in six plants and all inhabit saline environments. Furthermore, there are no reports of SP in freshwater or terrestrial plants. As such, this study investigated the presence of SP in freshwaters Eichhornia crassipes, Egeria densa, Egeria naja, Cabomba caroliniana, Hydrocotyle bonariensis and Nymphaea ampla. Chemical analysis identified sulfate in N. ampla, H. bonariensis and, more specifically, E. crassipes. In addition, chemical analysis, FT-IR spectroscopy, histological analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA), as well as agarose gel electrophoresis detected SP in all parts of E. crassipes, primarily in the root (epidermis and vascular bundle). Galactose, glucose and arabinose are the main monosaccharides found in the sulfated polysaccharides from E. crassipes. In activated partial thromboplastin time (APTT) test, to evaluate the intrinsic coagulation pathway, SP from the root and rhizome prolonged the coagulation time to double the baseline value, with 0.1 mg/mL and 0.15 mg/mL, respectively. However, SP from the leaf and petiole showed no anticoagulant activity. Eichornia SP demonstrated promising anticoagulant potential and have been selected for further studies on bioguided fractionation; isolation and characterization of pure polysaccharides from this species. Additionally in vivo experiments are needed and are already underway.     

Computed tomography: evaluation of stability tests and indirect tensile strength of field asphaltic mixtures

This work applies the computed tomography technique to the study of asphaltic mixtures. After analyzing Marshall stability and indirect tensile strength (IDT) tests, this technique was used for NonDestructive Testing (NDT) structural evaluations of field specimens. By analyzing the tomograms of the asphaltic mixtures it is possible to compare quality and physical conditions of field specimens, and also helps to interpret the distributions of tensions and deformations which occur in several types of solicitations imposed to the mixtures. The performance of asphaltic mixture could be more accurately predicted when all properties are known. The CT results of this work will be grouped with older and earlier data acquisition in order to compose a more complete database beyond years. Then these investigations could be used to increase the asphaltic mixtures quality by improving design and manufacturing procedures.     

Quality grading of cork planks with classification models based on defect characterisation

Coroebus undatus (F.) and Crematogaster scutellaris Ol.). A discriminant analysis was used to construct the classification model: the variable with the highest discriminant power was the total porosity in the transverse section, and the other variables were transformations of the specific width in the tangential section and the aspect ratio in the transverse section. The model classified two thirds of the samples in accordance with the manual classification currently used in the industry and all cases of disagreement referred to changes between contiguous quality classes.

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Use of Micronized Polyethylene Terephthalate (Pet) Waste in Asphalt Binder

The increase in living standards and social and economic development over the past three decades has increased the demand of waste discarded in the environment. In the last five years due to the widespread application of polyethylene terephthalate (PET) waste, improper disposal has become a serious problem in the maintenance of an environmental balance. Some additives have been developed during the last decades in order to improve the mechanical properties of asphalt binder according the rheological properties. This research aims to evaluate the implementation of PET in a modified binder. PET was mixed with the percentage of 4, 5, and 6 wt% within a binder. It was found that progressive addition PET increased pulp consistency and improved its elastic response. Addition of PET showed promise in antiaging action, as the higher oxidation levels decrease modified binders.