Age related changes in the elastic fiber system of the interfoveolar ligament

In order to evaluate age related changes of the elastic fiber system in the interfoveolar ligament, we studied the deep inguinal ring from 33 male cadavers aged from stillborn to 76 years. Selective and alternated staining methods for elastic fibers were performed to differentiate oxytalan, elaunin, and mature elastic fibers. We confirmed quantitative changes of the elastic fiber system with aging. There was a significant and progressive reduction of the oxytalan fibers (responsible for tissue resistance) and a significant increment in the mature elastic and elaunin fibers (responsible for tissue elasticity). Furthermore, there were structural changes in the thickness, shortness and curling of these mature elastic fibers. These changes induced loss of the elastic fiber function and loss of the interfoveolar ligament compliance. These factors predispose individuals to the development of indirect inguinal hernias that frequently emerge in adults and aged individuals, especially above the fifth decade.

Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method.

Sistema para realização de medidas de luminescência com excitação por Raios X

In this work is presented a versatile system for X-ray excited optical luminescence (XEOL) measurements. The apparatus was assembled from a sample holder connected to an optical fiber responsibly for the acquisition of the scintillation signal. The spectrum is registered with a CCD coupled in a spectrograph provided with diffraction gratings. The system performance was analyzed by exciting GdAlO3:Eu3+ 3.0 at.% with X-rays from a diffractometer and measuring the emission spectra. The system can be used to obtain precise and reliable spectroscopic properties of samples with various conformations without the loss of the required safety when dealing with ionizing radiations.

Sorption kinetics and intrapaticulate diffusivity of As(III) bioremediation from aqueous solution, using modified and unmodified coconut fiber

The pollution and toxicity problems posed by arsenic in the environment have long been established. Hence, the removal and recovery remedies have been sought, bearing in mind the efficiency, cost effectiveness and environmental friendliness of the methods employed. The sorption kinetics and intraparticulate diffusivity of As (III) bioremediation from aqueous solution using modified and unmodified coconut fiber was investigated. The amount adsorbed increased as time increased, reaching equilibrium at about 60 minutes. The kinetic studies showed that the sorption rates could be described by both pseudo-first order and pseudo-second order process with the later showing a better fit with a value of rate constant of 1.16 x 10-4 min-1 for the three adsorbent types. The mechanism of sorption was found to be particle diffusion controlled. The diffusion and boundary layer effects were also investigation. Therefore, the results show that coconut fiber, both modified and unmodified is an efficient sorbent for the removal of As (III) from industrial effluents with particle diffusion as the predominant mechanism.

Design of an adsorbent employing activated carbon fiber to remove lead

Zorflex® activated carbon fibers (ACF), reference FM100 198B, are used before and after an oxidizing procedure with H3PO4 to study the adsorption of Pb2+. The point of zero charge was determined for the modified and unmodified fiber giving values of 2.3 and 4.3, respectively. After oxidizing the ACF, the fiber showed to have a greater Pb2+ adsorption capacity in comparison with the unmodified fiber, which is related with the acid sites increase, where lead was mainly adsorbed. Determination of the BET area was carried out by nitrogen physisorption at 77K. ACFs presented superficial areas between 1000 and 1500 m²/g showing mostly, a microporous structure. The preliminary design of an adsorbent using the modified fiber is presented where the fiber superior physicochemical properties over the unmodified one are observed.

Characterization and treatment of sisal fiber residues for cement-based composite application

Sisal fiber is an important agricultural product used in the manufacture of ropes, rugs and also as a reinforcement of polymeric or cement-based composites. However, during the fiber production process a large amount of residues is generated which currently have a low potential for commercial use. The aim of this study is to characterize the agricultural residues by the production and improvement of sisal fiber, called field bush and refugo and verify the potentiality of their use in the reinforcement of cement-based composites. The residues were treated with wet-dry cycles and evaluated using tensile testing of fibers, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Compatibility with the cement-based matrix was evaluated through the fiber pull-out test and flexural test in composites reinforced with 2 % of sisal residues. The results indicate that the use of treated residue allows the production of composites with good mechanical properties that are superior to the traditional composites reinforced with natural sisal fibers.

Stereological study of the elastic fiber and smooth muscle cell system in the bovine and buffalo penis

Samples of ten penises of Mediterranean buffaloes and ten penises of Red Sindhi cattle were used. The thickness of the tunica albuginea (TA), distribution of smooth muscle cells (SMC) and volume density (Vv) of elastic system fibers in TA, corpus cavernosum (CC) and corpus spongiosum (CS) were evaluated. The Vv of elastic system fibers in buffalo and bovine penis was respectively 4.07% ±0.88% and 3.36% ±1.21% in TA; 17.32% ±2.21% and 13.14% ±1.27% (CC), 26.58% ±4.31% and 31.36% ±3.67% (CS). The CC of buffalo presented higher Vv of elastic fibers than bovine, while in the CS the Vv of elastic fibers in buffaloes was smaller than in cattle. The TA thickness showed a significant difference among the species studied. The arrangement of SMC in the bovine penises and in the water buffalo suggests that this pattern is common to animals that have fibroelastic penises.

Contrast sensitivity to angular frequency stimuli is higher than that for sinewave gratings in the respective middle range

This study compares contrast thresholds for sinewave gratings, or spatial frequencies (1/CSF) with contrast thresholds for angular frequencies (1/aCSF) and for radial frequencies, or J0 targets (1/rCSF). Observers had to differentiate between one of these frequency stimuli and a stimulus at mean luminance within a forced-choice procedure. All measurements were made with the same equipment, methods and subjects. Our results show higher sensitivity to, or lower thresholds for, angular frequencies when compared to either sinewave gratings or J0 targets. Contrast values in arbitrary units, in the lower threshold range for angular frequencies, were about half those required to differentiate sinewave gratings from mean luminance in its most sensitive range

Inhibitory effects in the detection of 1 cpd jo targets superimposed to angular frequency stimuli or sinewave gratings

Independence among channels processing different aspects of spatial information, including orthogonal stimuli, has been generally assumed in the literature. We tested independence between the processing of jo targets and the processing of either vertical sinusoidal gratings or angular frequency stimuli with suprathreshold summation. We found the detection of a jo target at 1 cpd to be affected in an inhibitory fashion by either background angular frequencies in the range of 3-96 cycles or sinewave gratings in the range of 0.8-3.0 cpd. These results demonstrate interactions both among orthogonal stimuli and among channels processing vertical sinewave gratings and jo target stimuli. Our discussion focuses on the hypothesis of frequency decomposition in polar coordinates

Glass pipette-carbon fiber microelectrodes for evoked potential recordings

Current methods for recording field potentials with tungsten electrodes make it virtually impossible to use the same recording electrode also as a lesioning electrode, for example for histological confirmation of the recorded site, because the lesioning procedure usually wears off the tungsten tip. Therefore, the electrode would have to be replaced after each lesioning procedure, which is a very high cost solution to the problem. We present here a low cost, easy to make, high quality glass pipette-carbon fiber microelectrode that shows resistive, signal/noise and electrochemical coupling advantages over tungsten electrodes. Also, currently used carbon fiber microelectrodes often show problems with electrical continuity, especially regarding electrochemical applications using a carbon-powder/resin mixture, with consequent low performance, besides the inconvenience of handling such a mixture. We propose here a new method for manufacturing glass pipette-carbon fiber microelectrodes with several advantages when recording intracerebral field potentials

Collagen arrangement in hepatic granuloma in mice infected with Schistosoma mansoni: dependence on fiber radiation centers

The collagen structure of isolated and in situ liver granuloma from Swiss Webster mice infected with Schistosoma mansoni was sequentially and three-dimensionally analyzed during different times of infection (early acute, acute, transitional acute-chronic, and chronic phases) by laser scanning confocal microscopy and electron scanning variable vacuum microscopy. The initial granuloma structure is characterized by vascular collagen residues and by anchorage points (or fiber radiation centers), from where collagenous fibers are angularly shed and self-assembled. During the exudative-productive stage, the self-assembly of these fibers minimizes energy and mass through continuous tension and focal compression. The curvature or angles between collagen fibers probably depends on the fibroblastic or myofibroblastic organization of stress fibers. Gradually, the loose unstable lattice of the exudative-productive stage transforms into a highly packed and stable architecture as a result of progressive compactness. The three-dimensional architecture of granulomas provides increased tissue integrity, efficient distribution of soluble compounds and a haptotactic background to the cells.

A comparative study of aging of the elastic fiber system of the diaphragm and the rectus abdominis muscles in rats

In the present study the age-related changes of the striated muscle elastic fiber system were investigated in the diaphragm and rectus abdominis muscles of 1-, 4-, 8- and 18-month-old rats. The activation patterns of these muscles differ in that the diaphragm is regularly mobilized tens of times every minute during the entire life of the animal whereas the rectus abdominis, although mobilized in respiration, is much less and more irregularly activated. The elastic fibers were stained by the Verhoeff technique for mature elastic fibers. Weigert stain was used to stain mature and elaunin elastic fibers, and Weigert-oxone to stain mature, elaunin and oxytalan elastic fibers. The density of mature and elaunin elastic fibers showed a progressive increase with age, whereas the amount of oxytalan elastic fibers decreased in both diaphragm and rectus abdominis muscles and their muscular fascias. These age-related quantitative and structural changes of the elastic fiber system may reduce the viscoelastic properties of the diaphragm and rectus abdominis muscles, which may compromise the transmission of tensile muscle strength to the tendons and may affect maximum total strength.

Dietary fiber intake, stool frequency and colonic transit time in chronic functional constipation in children

The objective of the present study was to evaluate associations between fiber intake, colonic transit time and stool frequency. Thirty-eight patients aged 4 to 14 years were submitted to alimentary evaluation and to measurement of colonic transit time. The median fiber intake of the total sample was age + 10.3 g/day. Only 18.4% of the subjects presented a daily dietary fiber intake below the levels recommended by the American Health Foundation. In this group, the median left colonic transit time was shorter than in the group with higher dietary fiber intake (11 vs 17 h, P = 0.067). The correlation between stool frequency and colonic transit time was negative and weak for left colon (r = -0.3, P = 0.04), and negative and moderate for rectosigmoid and total colon (r = -0.5, P<0.001 and r = -0.5, P<0.001, respectively). The stool frequency was lower in the group with slow transit time (0.8 vs 2.3 per week, P = 0.014). In conclusion, most patients with chronic functional constipation had adequate dietary fiber intake. The negative correlation between stool frequency and colonic transit time increased progressively from proximal segments to distal segments of the colon. Patients with normal and prolonged colonic transit time differ in terms of stool frequency.

Dietary fiber, energy intake and nutritional status during the treatment of children with chronic constipation

The present prospective study was carried out to determine dietary fiber and energy intake and nutritional status of children during the treatment of chronic constipation. Twenty-five patients aged 2 to 12 years with chronic constipation were submitted to clinical evaluation, assessment of dietary patterns, and anthropometry before and after 45 and 90 days of treatment. The treatment of chronic constipation included rectal disimpaction, ingestion of mineral oil and diet therapy. The standardized diet prescribed consisted of regular food without a fiber supplement and met the nutrient requirements according to the recommended daily allowance. The fiber content was 9.0 to 11.9 g for patients aged less than 6 years and 12.0 to 18.0 g for patients older than 6 years. Sixteen patients completed the 90-day follow-up and all presented clinical improvement. The anthropometric variables did not change, except midarm circumference and triceps skinfold thickness which were significantly increased. Statistically significant increases were also found in percent calorie intake adequacy in terms of recommended daily allowance (55.5 to 76.5% on day 45 and to 68.5% on day 90; P = 0.047). Percent adequacy of minimum recommended daily intake of dietary fiber (age + 5 g) increased during treatment (from 46.8 to 52.8% on day 45 and to 56.3% on day 90; P = 0.009). Food and dietary fiber intake and triceps skinfold thickness increased during follow-up. We conclude that the therapeutic program provided a good clinical outcome.

Contrast sensitivity to angular frequency gratings is not higher than to Cartesian gratings

When contrast sensitivity functions to Cartesian and angular gratings were compared in previous studies the peak sensitivity to angular stimuli was reported to be 0.21 log units higher. In experiments carried out to repeat this result, we used the same two-alternative forced-choice paradigm, but improved experimental control and precision by increasing contrast resolution from 8 to 12 bits, increasing the screen refresh rate from 30 Hz interlaced to 85 Hz non-interlaced, linearizing the voltage-luminance relation, modulating luminance in frequencies that minimize pixel aliasing, and improving control of the subject's exposure to the stimuli. The contrast sensitivity functions to Cartesian and angular gratings were similar in form and peak sensitivity (2.4 cycles per visual degree (c/deg) and 32 c/360º, respectively) to those reported in a previous study (3 c/deg and 32 c/360º, respectively), but peak sensitivity to angular stimuli was 0.13 log units lower than that to Cartesian stimuli. When the experiment was repeated, this time simulating the experimental control level used in the previous study, no difference between the peak sensitivity to Cartesian and angular stimuli was found. This result agrees with most current models that assume Cartesian filtering at the first visual processing stage. The discrepancy in the results is explained in part by differences in the degree of experimental control.