Atributos de Latossolos remanescentes em áreas onde atualmente ocorre o processo de bissialitização, em Búzios (RJ).

Os sedimentos da formação Barreiras (Terciário) ocorrem numa faixa ao longo do litoral brasileiro, ocupando extensas áreas, do norte do Rio de Janeiro aos estados da região nordeste, constituindo os Tabuleiros Costeiros. Ao sul de Campos (RJ), a ocorrência da formação Barreiras no Estado, é descontínua, ocorrendo na forma de bolsões isolados, dentre os quais um está situado a 125 km de distância, em Armação de Búzios (RJ), local selecionado para este estudo. Partindo-se de alguns atributos de dois perfis representativos desses solos como referência, localizados em Campos (RJ) e desenvolvidos a partir dos sedimentos da formação Barreiras, procurou-se determinar as transformações que eles teriam passado, sob condições mais secas. Os dois perfis foram caracterizados do ponto de vista morfológico (macro e micro), analítico (físico, químico e mineralógico) e comportamento físico-hídrico

EMOTIONAL ELEMENTS ON LEARNING STYLE PREFERENCE OF HIGH AND LOW PERFORMING JUNIOR MARINE TRANSPORTATION STUDENTS

ABSTRACT This study aimed to determine the learning style of the Marine Transportation students in a private Asian university in terms of emotional elements as to motivation, persistence, responsibility and structure; and to compare the learning styles of high and low performing Marine Transportation students. Descriptive type of research was utilized in the study. Results showed that high and low performing students strongly agree that they enjoy learning and they get a sense of accomplishment from achieving and they like to learn most of the time especially when the subject is interesting. The high performing students have significantly higher persistence in completing the things they begun as well as in enjoying working on several tasks simultaneously. Both groups of marine students strongly agree that they feel best when they do things they know they should do while high performing students have significantly higher responsibility on doing conventional things depends on the tasks and on how they feel about the circumstances compared to the low performing students. Marine students wanted to be instructed completely in order for them to perform the activities accurately with the help of other members of the group through teamwork

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Calibration of electrospray mass spectrometers with rccc-2,8,14,20-tetra-n-octyl-5,11,17,23-tetrahydroxyresorc[4]arene in the high mass range up to m/z 6000

Letzel M, Agena C, Mattay J. Calibration of electrospray mass spectrometers with rccc-2,8,14,20-tetra-n-octyl-5,11,17,23-tetrahydroxyresorc[4]arene in the high mass range up to m/z 6000. EUROPEAN JOURNAL OF MASS SPECTROMETRY. 2001;7(1):35-38.rccc-2,8,14,20-Tetra-n-octyl-5,11,17,23-tetrahydroxyresorc[4]arene has the property to form cluster ions in both positive- and negative-ion mode with good intensity without the addition of any modifiers such as cesium. These cluster ions may be used for the calibration of electrospray mass spectrometers in the mass range up to m/z 6000

Interfacial electrostatics guiding the crystallization of CaCO3 underneath monolayers of calixarenes and resorcarenes

Volkmer D, Fricke M, Agena C, Mattay J. Interfacial electrostatics guiding the crystallization of CaCO3 underneath monolayers of calixarenes and resorcarenes. JOURNAL OF MATERIALS CHEMISTRY. 2004;14(14):2249-2259.The amphiphilic octaacids rccc-4,6,10,12,16,18,22,24-octakis-O-(carboxymethyl)-2,8,14,20-tetra(n-u ndecyl) resorc[4] arene (1) and 5,11,17,23,29,35,41,47-octakis(1,1,3,3-tetramethylbutyl)-49,50,51,52,53, 54,55,56-octa( carboxymethoxy) calix[8] arene (2) form stable monolayers at the air - water interface which induce growth of CaCO3 crystals at the monolayer-solution interface. Uniformly (012) oriented rhombohedral calcite single crystals grow underneath a monolayer of 2, whereas crystallization under a monolayer of 1 preferentially leads to formation of acicular aggregates of aragonite crystals. While polymorph selection and orientations of the CaCO3 crystals critically depend on the average charge density of the monolayer, the molecular shape and the particular Ca coordination behaviour of the amphiphiles that form the monolayer are of minor importance. CaCO3 crystal growth underneath monolayers of macrocyclic amphiphiles is briefly reviewed and the present experimental observations are compared to previous related investigations on "template-induced'' biomimetic mineralization

Chiral discrimination on the host-guest complexation of resorc[4]arenes with quarternary amines

Mehdizadeh A, Letzel M, Klaes M, Agena C, Mattay J. Chiral discrimination on the host-guest complexation of resorc[4]arenes with quarternary amines. EUROPEAN JOURNAL OF MASS SPECTROMETRY. 2004;10(1):649-655.The interaction of inherently chiral resorc[4]arenes with different chiral ammonium ions was measured by electrospray ionization mass spectrometry. For this purpose, one enantiomer of the ammonium guests was labeled with deuterium to distinguish the enantiomers by their mass. We synthesized the ammonium salts by the reaction of chiral primary amines with either CH3I or CD3I and analyzed the resulting ammonium iodides by nuclear magnetic resonance and optical rotation. The complexation experiments were performed by mixing the chiral host with various ratios of the unlabeled guest and its labeled enantiomer. By analyzing the integrals of the host-guest complexes, we observed a chiral discrimination effect and a secondary isotope effect as well

Synthesis and structural studies of 5, 11, 17, 23-tetrahydroxyresorc[4]arenes

Gerkensmeier T, Agena C, Iwanek W, et al. Synthesis and structural studies of 5, 11, 17, 23-tetrahydroxyresorc[4]arenes. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES. 2001;56(10):1063-1073.Hydroxyresorc[4]arenes are bowl-shaped calixarene compounds. Herein we report the synthesis and the results of X-ray diffraction examinations of six hydroxyresorc[4]arenes, one of them could be crystallized in two conformations. All compounds co-crystallize with different solvent molecules, linked together by hydrogen bonds. It is known that hydroxyresorc[4]arenes are capable of forming large aggregates, a number of different compounds have been prepared, some of them could be crystallized and investigated by single crystal methods. Most of the compounds tend to form polarity-induced double layers

Self-assembly of 2,8,14,20-tetraisobutyl-5,11,17,23-tetrahydroxyresorc[4]arene

Gerkensmeier T, Iwanek W, Agena C, et al. Self-assembly of 2,8,14,20-tetraisobutyl-5,11,17,23-tetrahydroxyresorc[4]arene. EUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 1999;(9):2257-2262.We report herein the observation of a hexameric structure of a hydroxyresorc[4]arene in the solid state, enclosing a large interior space. This artificial molecular container is stabilized only by hydrogen bonds. The tendency to form aggregates in solution is demonstrated mainly by means of ESI-MS methods

First synthesis, isolation and characterization of enantiomerically pure and inherently chiral resorc[4]arenes by Lewis acid cyclization of a resorcinol monoalkyl ether

Klaes M, Agena C, Kohler M, et al. First synthesis, isolation and characterization of enantiomerically pure and inherently chiral resorc[4]arenes by Lewis acid cyclization of a resorcinol monoalkyl ether. EUROPEAN JOURNAL OF ORGANIC CHEMISTRY. 2003;(8):1404-1409.Cyclization of resorcinol monoalkyl ethers with aliphatic aldehydes leads to the corresponding racemic mixtures of C-4-symmetric rccc-resorc[4]arenes. Separation of these isomers was achieved by mono-O-functionalization of the rccc-2,8,14,20-tetramethylresorc[4]arene (2) with (S)-(+)-10-camphorsulfonyl chloride leading to a diastereomeric mixture of (+)-5a and (-)-5b. After removal of the chiral auxiliary the inherently chiral pure enantiomers (+)-2 and (-)-2 were obtained. Further enantiomerically pure rccc-resorc[4]arenes were obtained by cyclization of (+)-3-[(2S)-2-methylbutoxy]-phenol (6) followed by chromatographic separation. The resulting diastereomeric resorc[4]arenes (+)-7a and (-)-7b were examined by CD spectroscopy, showing a perfect mirror image in all solvents examined. This indicates that the resorcarene cavities of (+)-7a and (-)-7b are essentially enantiomers of each other. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)