Determinação quantitativa de TNT e HNS por TG e FT-IR

2,4,6-trinitrotoluene (TNT) is an energetic material that shows scarce crystalline properties that can be improved by addition of 2,2',4,4',6,6'-hexanitrostilbene (HNS) in the crystallization process. HNS is a very important high explosive used in a variety of military, aerospace and industrial formulations owing to its suitable properties. It is an insensitive and thermal stable explosive that can be produced from 2,4,6-trinitrotoluene (TNT). The purpose of this work is the quantitative determination of HNS and TNT in explosives by thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR).

Sensores ópticos com detecção no infravermelho próximo e médio

Optical chemical sensors with detection in the near and mid infrared region are reviewed. Fundamental concepts of infrared spectroscopy and optical chemical sensors are briefly described, before presenting some aspects on optical chemical sensors, such as synthesis of NIR and IR reagents, preparation of new materials as well as application in determinations of species of biological, industrial and environmental importance.

Discrimination of native wood charcoal by infrared spectroscopy

Brazil is one of the largest producers and consumers of charcoal in the world. About 50% of its charcoal comes from native forests, with a large part coming from unsustainable operations. The anatomic identification of charcoal is subjective; an instrumental technique would facilitate the monitoring of forests. This study aimed to verify the feasibility of using medium and near infrared reflectance spectroscopy to discriminate native (ipê) from plantation charcoals (eucalyptus). Principal Components Analysis, followed by Discriminant Factorial Analysis formed two different groups indicated by Mahalanobis distances of 40.6 and 80.3 for near and mid infrared, respectively. Validation of the model showed 100% efficacy.

Preliminary data on Brazilian monofloral honey from the northeast region using FT-IR ATR spectroscopic, palynological, and color analysis

Fourier transform infrared attenuated total reflectance (FT-IR ATR) spectroscopy was used to determine 14 different measurands in northeast Brazilian honey samples. Nine different honey samples (six monofloral and three polyfloral) from 2009 obtained from the company CEARAPI underwent FT-IR ATR, palynological, color, and sensorial analysis to obtain preliminary results for these types of honey. The results showed that there are five monofloral, three bifloral, and one extrafloral honey, and also that mid-infrared spectrometry can be used as a screening method for the routine analysis of Brazilian honey, with the advantages of being rapid, nondestructive, and accurate.

White mold detection in common beans through leaf reflectance spectroscopy

ABSTRACT This study aimed to identify wavelengths based on leaf reflectance (400-1050 nm) to estimate white mold severity in common beans at different seasons. Two experiments were carried out, one during fall and another in winter. Partial Least Squares (PLS) regression was used to establish a set of wavelengths that better estimates the disease severity at a specific date. Therefore, observations were previously divided in two sub-groups. The first one (calibration) was used for model building and the second subgroup for model testing. Error measurements and correlation between measured and predicted values of disease severity index were employed to provide the best wavelengths in both seasons. The average indexes of each experiment were of 5.8% and 7.4%, which is considered low. Spectral bands ranged between blue and green, green and red, and red and infrared, being most sensitive for disease estimation. Beyond the transition ranges, other spectral regions also presented wavelengths with potential to determine the disease severity, such as red, green, and near infrared.

IR - spectroscopic characterization of biominerals in marattiaceaeus ferns

(IR - spectroscopic characterization of biominerals in marattiaceaeus ferns). Frond samples of the eusporangiate ferns Marattiaceae genera Angiopteris, Christensenia, Danaea and Marattia were investigated by infrared spectroscopy, under different experimental conditions. The results confirmed the previously reported accumulation of biogenic silica (SiO2) in tissues of these ferns and also showed, for the first time, the presence of calcium oxalate in this group of plants, probably as weddellite. The ability to biomineralize SiO2, to produce and accumulate biogenic silica, is suggested now to be a general family trait of the Marattiaceae.

High pressure near infrared study of the mutated light-harvesting complex LH2

The pressure sensitivities of the near infrared spectra of the light-harvesting (LH2) complex and a mutant complex with a simplified BChl-B850 binding pocket were compared. In the mutant an abrupt change in the spectral properties occurred at 250 MPa, which was not observed with the native sample. Increased disorder due to collapse of the chromophore pocket is suggested.

Scanning electron microscopy and X-ray spectroscopy applied to mycelial phase of sporothrix schenckii

Scanning electron microscopy applied to the mycelial phase of Sporothrix schenckii shows a matted mycelium with conidia of a regular pattern. X-Ray microanalysis applied in energy dispersive spectroscopy and also in wavelength dispersive spectroscopy reveals the presence of several elements of Mendeleef's classification.

Proton magnetic resonance spectroscopy of the frontal lobe in schizophrenics: a critical review of the methodology

Schizophrenic patients undergoing proton magnetic resonance spectroscopy show alterations in N-acetyl aspartate levels in several brain regions, indicating neuronal dysfunction. The present review focuses on the main proton magnetic resonance spectroscopy studies in the frontal lobe of schizophrenics. A MEDLINE search, from 1991 to March 2004, was carried out using the key-words spectroscopy and schizophrenia and proton and frontal. In addition, articles cited in the reference list of the studies obtained through MEDLINE were included. As a result, 27 articles were selected. The results were inconsistent, 19 papers reporting changes in the N-acetyl aspartate levels, while 8 reported no change. Methodological analysis led to the conclusion that the discrepancy may be due the following factors: (i) number of participants; (ii) variation in the clinical and demographic characteristics of the groups; (iii) little standardization of the acquisition parameters of spectroscopy. Overall, studies that fulfill strict methodological criteria show N-acetyl aspartate decrease in the frontal lobe of male schizophrenics.

Vegetation near Santa Teresinha, NE Mato Grosso.

The Santa Tenesinha region in northeaster Mato Grosso has a varied vegetation which is principally hammock pantanal. The flat clayey alluvial ground between the hummocks is coveted with a continuous non-cerrado ground cover dominated by grasses but which harbors sedges and a lange herb flora. No woody plants grow in it. The tops of the 10-20m wide, slightly elliptical hummocks, 1.5-2 m high, 10-40 per hectare, are covered with cerrado plants: herbs, semlshrubs, thin- and thick-stemmed shrubs and low trees. For 4-5 months during the latter part of the rainy season, the regional water table rises to the surface and the ground between the hummocks becomes saturated or floods up to 1.5-2 m deep. The tops of the hummocks almost always remain above high water level. In the dry season the surface soil dries out completely. This alternation of saturation or shallow flooding and dryness, prevents woody plant, growth between the hummocks, and except for a few tolerant species, also prevents woody plant. growth on the lower part of the hummochs. The gallery forests in the pantanal are seasonally flooded more deeply but their soil does not dry out so thonoughly in the dry season so woody plant growth is not prevented.

Small mammal abundances in isolated and non-isolated primary forest reserves near Manaus, Brazil

Abundances of msmall terrestrial mammals were estimated in 10 and 100-ha, isolated and non-isolated primary forest reserves near, Manaus, Brazil between October 1983 and March 1984. The smalt mammal abundance pattern In a 10 ha reserve isolated fan appoximately three years differed significantly from that in othen reserves, primarily due to higher capture rates of Marmosa cinerea, Rhipidomys mastacalis, and Onyzomys paricola in the isolated reserve. Viet type and re-invasion potential may be important factors the small mammal communities in forest patches. Variation the small mammal community among othen reserves was pnimanlty due to variatton In the abundances of Proechimys and 0. capito. At least pant of this vantation was attributable to temporal efects, but variation due to reserve effects also was suggested. Small mammals were much more abundant in the reserves during the present study than in 1982.

EARTHWORM ACTIVITY IN FOREST AND SAVANNA SOILS NEAR BOA VISTA, RORAIMA, BRAZIL

From May to December, 1992 we studied the earthworm activity, as part of the ECOFIT Program at Surrão ( 30km from Boa Vista), verifying the duration of the activity and quantifying it through the casts deposited on the soil surface. Three transects were stablished: a 100m long in the savanna, a 40m in the transitional area and 100m long in the forest. Specimens were collected monthly along the transects according to the method proposed by TSBF and the casts were collected from the squares previously placed on the transects. Two earthworm species were found in the three areas: Pontoscolex roraìmensis and Pontoscolex corethrurus. The first species depositing its casts on the soil surface. Rainy season wich usually occurs from April to August, determined the duration of activity for the two species (however, 1992 was atypical in that rainy season, only started in May). P. roraìmensis produced casts in the three areas from May to August followed by aestivation. In the savanna, P. corethrurus started aestivation in the same period as P. roraìmensis but remained active until November in the two other areas. P. roraìmensiswas found up 50m from the forest border, being associated to the presence of Curatella americana and Byrsonima sp, two typical savanna bushes.

On occurrence, habitat specificity and natural history of adult tiger beetles (Coleoptera: Carabidae: Cicindelinae) near Manaus, Central Amazonia, and key to the larvae of tiger beetle genera

Over a seven year period from 1991 to 1997, 22 species of tiger beetles, representing nine genera, were recorded near Manaus, Brazil. In the Whitewaterfloodplains along the Rio Solimões-Amazonas (Ilha de Marchantaria), three diurnal species inhabit inundation forests and six species (two diurnal, four nocturnal) live in open areas. Data on their natural history and adaptation to living conditions in floodplains are presented. Fifteen species were located on non-flooded uplands (Reserva Florestal A. Ducke). Five diurnal species inhabit the forest floor, two species are canopy dwellers, and eight species (seven diurnal, one nocturnal) live in open areas on whitesand or laterite. Only one species, Pentacomia lacordairei, was found in both floodplain and upland forests. A key to the larvae of tiger beetle genera located near Manaus is presented.

Spatial and temporal distribution of a tiger beetle guild (Coleoptera: Carabidae: Cicindelinae) along a 105m long transect in the reserva florestal A. Ducke near Manaus (Central Amazonia)

The spatial and temporal distribution of a guild of eight diurnal tiger beetle species was studied on a 105 m long transect near the field station of the Reserva Florestal A. Ducke near Manaus (AM), Brazil. The transect followed a path that included both shaded and an open areas. Five of the species, restricted to primary forest, occurrred only in shaded areas of the transect, and three species occurred in open areas. Of all eight species only two of the open habitat species showed no clear seasonality in adult activity. In six species the activity of adults was limited to the rainy season. The most pronounced annual rhythm was found in Pentacomia ventralis, an open habitat species. Activity of adults was limited to October/November. First in-star larvae appeared shortly thereafter. Larval development mainly took place from January to May. The third instar larva entered a dormancy which lasted up to 10 months, and which enabled the synchronisation of emerging adults with annual seasons.