bluuebunny/crossref_metadata_2025 huggingface dataset:
A microscopic perspective of a microreactor
Authors: Carvalho F. , Paradiso P. , Fernandes P.
Published: August 2013

The use of microreactors in (bio)chemical processes has been gaining relevance in the last decade. The low consumption of reagents, the possibility of continuous operation and the faster translation from lab- to production scale are some of the several advantages of these devices. The whole results in cost reductions in process development. Enzyme catalyzed reactions have proved to be an excellent alternative to the use of chemicals due to its ability to catalyze the most complex chemical processes under benign experimental and environmental conditions. In this way, enzymes may be crucial to the implementation of a much more sustainable chemical industry.

The present work is within such scope, using as model system the immobilization of invertase in glass (silica) microchannels, for the production of fructose syrups through sucrose hydrolysis. The immobilization of the enzyme was achieved through treatment of the substrate with a sequence of coatings (Figure 1). Activation of the inner surface of the microchannels with 3-aminopropyltriethoxysilane (APTES) was followed by the introduction of a spacer, glutaraldehyde. Lastly the enzyme solution was introduced in the presence of sodium cyanoborohydride, in order to enhance the stability of the support-enzyme binding.

The characterization of the coatings at each stage of the immobilization protocol was carried out to confirm the change of the microchannel surface. Such studies were performed using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) analysis (Figure 1).

The results obtained, namely the shifts on the surface roughness corroborate that the several coatings were successfully applied and the enzyme immobilized. Moreover, the immobilization approach used proved to be highly effective, resulting on successful continuous use of the microreactor for a period of 30 days with roughly constant full conversion of a sucrose solution of 50g/l, at a flow rate of 7µl/minute (Figure 2).

Future work will involve a more extensive characterization of the several coatings by Quartz Crystal Microbalance which will be decisive to achieve a better comprehension of the coating phenomena and hence optimize the immobilization process.

The authors would like to thank Fundação para a Ciência e a Tecnologia, Portugal, for financial support through contracts under the program Ciência 2007 awarded to P. Fernandes, for the doctoral grant SFRH/BD/74818/2010 awarded to F. Carvalho and for the doctoral grant SFRH/BD/71990 /2010 awarded to Patrizia Paradiso.
Membranoproliferative glomerulonephritis with C3 and intramembranous dense deposits
Authors: Carvalho F. , Viana H. , Alves de Matos A.P. , Amoedo M.
Published: August 2013

Membranoproliferative glomerulonephritis (MPGN) encompasses 7 to 10% of all biopsied glomerulonephritis. They are divided in: MPGN type I; MPGN type II and MPGN type III, being primary or secondary. MPGN type I are the most frequent, MPGN types II and III are very rare and difficult to diagnose without clinical and morphologic findings integration. MPGN type II or Dense Deposit Disease has a varied morphologic appearance with a few numbers of cases showing a membranoproliferative pattern by Light microscopy (LM). Electron microscopy (EM) is pivotal to confirm the diagnosis.

We present a case of 35 years old man, with nephrotic proteinuria and mild renal insufficiency since 2 years. The only relevant clinical data is facial lipodystrophy. Complement 3 (C3) was low and C3 nephritic factor negative. There were not other relevant abnormalities. Renal biopsy was fixed in buffered formaldehyde 10% and performed for LM. The frozen fragment, prepared for observation by fluorescence microscopy - immunofluorescence (IMF) -, was prepared to be stained with florescent anti-serums, against immunoglobulines (IgG, IgA and IgM) and complement factors (C3, C4, and C1q). EM was later done on tissue formaldehyde fixed reprocessed from paraffin-embebbed for LM, because there was no tissue fragment fixed in glutaraldehyde.

LM showed variable endocapillary hypercelullarity, with neutrophils infiltration. Capillary walls were thickened due to the deposition of elongate and ribbon-like deposits. Few double contours were visible (Figure 1a). IMF demonstrated the presence of C3 deposits in the capillary walls and mesangium (Figure 1b). EM confirmed the presence of an intramembranous dense deposit along basement membrane which was thickened (Figure 1c). LM and IMF findings favored the diagnosis of MPGN type II with C3 deposits and thickening of basement membrane. Nevertheless EM was essential to confirm intramembranous unequivocally dense deposits.

MPGN type II is a rare glomerulonephritis mediated by complement deregulation. The integration of clinical and morphologic findings is essential to get a correct diagnosis. In this setting EM is highly distinctive and required for a definitive diagnosis.
Light microscopy studies on mice testis after the nutritional supplement chromium(III)-tris(picolinate)
Authors: Ferreira M. , Santos T.M. , Pereira M.L.
Published: August 2013

Cr(III)-tris(picolinate), [Cr(pic)3], is a very common dietary supplement, recommended for humans, cattle and swine. Chromium is considered an essential trace element, when in oxidation state +3, with some of its compounds seeming to have a beneficial effect on blood sugar regulation mechanisms. However, the safety of the use of a particularly popular Cr(III) compound, ie [Cr(pic)3], remains debatable. Clastogenic, and mutagenic features have been reported by Stearns and co-workers, although surrounded by a controversial and contradictory multitude of publications on this subject. The present work aims to study the effects of [Cr(pic)3] on mice spermatogenesis.

Cr(III)-tris(picolinate) was synthesized and characterized according to the literature. Its composition as a mononuclear complex was tested by ESI-MS and by X-ray powder diffraction followed by single-crystal simulation calculations.

Male adult CDI mice from Harlan (Spain) were divided in groups and orally given 25 mg/kg and 50 mg/kg/body weigh/daily of [Cr(pic)3] for two weeks. Controls were also done. Behaviour and body weight were monitored throughout the experiments. After sacrifice, testis were collected, weighed, and fixed in Bouin´s solution. Organs were then prepared for histology using routine techniques. Animal experiments were conducted according to ethics procedures. Histological sections of control group evidenced normal regular features (Fig. 1a). However considerable damage was observed in both experimental groups in a dose dependent manner. In fact, seminiferous tubules showed degenerative changes within epithelium, namely vacuolation and sloughing of immature germ cells into the lumen in the group given the lowest dose (Fig.1 b,c). The high dosed group displayed more conspicuous injury within testis, namely strongly atrophic seminiferous tubules devoid of germs cells and strong vacuolation (Figs.1d-f).

The results of this study have shown an increased risk of adverse events in mice receiving 50 mg/kg/body weight of [Cr(pic)3]. However, little potential for adverse reproductive and developmental effects namely on progeny was recently described for male mice fed a diet containing 200 mg/kg/day [Cr(pic)3]. In conclusion, concerns about using dietary supplements based on [Cr(pic)3] remain to be elucidated in future work.

This work was financed by CICECO, Aveiro University, Portugal.
Histological staining approaches for high-quality imaging of Actinia equina and Anemonia sulcata anatomy
Authors: Gadelha J. , Morgado F. , Soares A.M.V.M.
Published: August 2013

Sea anemones species identification of can be difficult, especially in the field. The taxonomic keys currently utilised are based mainly on histological differences and therefore require collection of whole animals. Furthermore, histological analysis of sea anemones requires considerable expertise and worldwide sea anemones histological descriptions are still limited. Here it is reported a detailed histological description of the internal structure of the two most conspicuous species in tidal pool communities in European shores, Actinia equina and Anemonia sulcata. This species description makes them excellent models for studying reproductive strategies that are instrumental in establishing and maintaining new populations. Therefore they are potential indicator species important both for micro and macro scale monitoring programs. The anatomy and histology of main organs of the studied sea anemones were described. The different colour morphs of the species were studied. Fine histological details of their muscular and digestive systems and appendages, down to the cellular level, were studied. They are two-germinal layer animals and possess radial symmetry in body form. Samples of the main organs of sea anemones including epidermis, tentacles, mesentery, gonads and digestive tract (mouth, stomodaeum and gastrovascular cavity) were processed for histological examination according to procedures described elsewhere [1,2]. The epithelia were composed of epithelio-muscular cells, in which many gland cells were distributed. Three types of cnidoblasts (nematooysts) were observed in the epithelioma of the tentacles, mesentery filament and stomodaeum. Cnidoblasts in different places have different functions. The gonads were of the follicular type and were composed of germ cells and nutritional cells. The investigation of the internal organization of invertebrate communities provides important information on the organism’s biology with special interest for the study of ecological processes to evaluate their reproductive modes in order to understand how they may reflect their dispersal strategies [1, 2]. Traits that influence reproduction in animal and plant species have been a central focus of evolutionary biology. Therefore, considering their basal position in evolution, the Anthozoa (Cnidaria) provide important models for further understanding processes affecting reproductive strategies in the eumetazoan (i.e., cnidarian-bilaterian) ancestor and in modern vertebrates.

This work was supported by the Portuguese Foundation for the Science and Technology – Portugal and FEDER funds, through the Projects: PTDC/MAR/464729/2006 and FCT/CNPq (Brazil), Project 6818, Programme 19/ 004.
Histopathology of Zinc exposition in Actinia equina L. (Anthozoa, Actiniaria)
Authors: Gadelha J. , Ferreira C. , Soares A.M.V.M. , Pereira M.L. , Morgado F.
Published: August 2013

Zinc is a trace metal that is regularly found at pollution sites, amongst other metals and pollutants, contributing to the toxicity of marine ecosystems. In this study zinc acute toxicity tests were conducted on the sea anemone Actinia equina. This sea anemone presents a wide geographic distribution on rocky shore marine habitats, is quite resistant to some degree of various forms of contaminants and plays an important ecological key role in the marine environments.

After a period of acclimatising on a flow through system, organisms of the same average size were exposed to different concentrations of zinc solution during a period of 96 hours (0 µg/l, 10 µg/l, 50 µg/l, 100 µg/l, and 200µg/l). The histological processing of the specimens was performed using standard procedures, slightly modified due to the peculiar nature of the biological material.

The general effects exhibited necrosis of tentacles, mesenterial filaments, and in the gastrodermal regions (Figures 1, 2 and 3). It were observed tentacular cysts, black particulate accumulations in the gastrodermis, hypertrophied cells in the lobes of the mesenteries filaments, and spirocyst and associated necrosis (Fig. 2-3). All anemones exhibited extensive areas of tissue necrosis, degeneration of the epidermis in various stages, with loss of mucous cells, vacuolation, necrosis and ptychocysts from the epidermis, necrosis of retractor muscles and ducts (Figures 2-3). Neoplasms of the gastrointestinal tract and gonads were observed in internal structures. In the former, modifications of the mesenteries such as intensive fragmentation, vacuolization and epithelial thinning and in the latter abnormal gonad development and necrosis were noted (Figures 2-3).

The data suggests that Actinia equina may be adversely affected by acute exposures to high levels of zinc as seen during laboratory exposures of other invertebrates and is also probably sensitive to acute exposures to metal’s toxic sediments in the marine environment. The loss of mucous secretory cells and ptychocysts from the epidermis suggest that energy reserves for cell replenishment were adversely affected. Mucus production in benthic cnidarians is necessary to prevent burial by sedimentation and to protect against toxins or invading microorganisms. The serious effects on the gastrodermis integrity indicate that sea water in the coelenteron is no longer circulated. The observed modifications could be considered as a general cnidarians response to stress.

Further investigations of bioaccumulation, physiology, and histopathology in this anemone and other anthozoans from polluted environments should prove to be valuable in pollution monitoring studies, as they have for other benthic invertebrates

Acknowledgments

This work was supported by the Portuguese Foundation for the Science and Technology – Portugal and FEDER funds, through the Projects: PTDC/MAR/464729/2006 and FCT/CNPq (Brazil), Project 6818, Programme 19/ 004.
The importance of structural diversity of spores in the taxonomy of Aspergillus (section Nigri)
Authors: Simões M.F. , Santos C. , Lima N.
Published: August 2013

Species of Aspergillus from section Nigri, also known as black aspergilli, are distributed worldwide and have been widely used for purposes of various types such as: biotechnological, industrial, medical, among others. They have been extensively studied for being the causing agents of biodeterioration of commodities and food.

Within this section, new species have been recently described and among them Aspergillus ibericus and Aspergillus uvarum were both isolated from grapes. The polyphasic approach used in the analysis of these species, either by morphological techniques as well as by molecular methods, allowed not only their characterisation but also their consequent separation from all others in the section. Microbial taxonomy has the identification of species as one of its fundamental goals. Data such as: morphological characteristics description, physiological and biochemical properties, ecological roles, and societal risks or benefits, are key elements in any fungal identification process. But, this process is subjected to periodic changes due to frequent revisions of the taxonomic schemes, therefore becoming time consuming and more demanding and difficult, even for skilled specialists. Furthermore, each taxonomic group has specialised literature, terminology and characters. This takes place since identifications have difficulties of consensual naming, depending on the criteria used and the amount of information available when producing all data. It is increasingly becoming clear that, to better achieve a more accurate concept of species, microbial identification and authentication require a polyphasic approach to produce consistent, useful and quality data.

Characterisation of morphologic and structural aspects of spores from Aspergillus strains, section Nigri, has been carried out using scanning electron microscopy (SEM) and intends to contribute to the associated data of the strains from this section.

Colonies from 13 Aspergillus from section Nigri, from the Micoteca da Universidade do Minho (MUM), were grown at 25 ºC for 3 or 4 days in malt extract agar directly mounted in a sterilised SEM stub. The samples were covered with a mixture of gold and platinum (80/20%) and then examined in the SEM [NanoSEM - FEI NovaTM 200 (FEG/SEM); EDAX - Pegasus X4M (EDS/EBSD)]. A stereomicroscope (Leica MZ12.5) was used to have a clear image comparison of the size of the conidial head.

Although the analysed strains presented dimensional, morphological and structural diversity, common or typical features could be inferred and related to each taxon like those represented in Fig 1.

From the SEM analysis we were able to conclude that in the section Nigri of genus Aspergillus the spore wall ornamentation, and its size and shape continue to present themselves as important primary diagnostic traits for species differentiation.
Investigation of elemental distribution in cat femoral head by nuclear microprobe and SEM for Paget disease of bone studies
Authors: Santos C. , Fonseca M. , Corregidor V. , Alves L.C. , Luis H. , Capelão M. , Branco J.C. , Carvalho P.A. , Jesus A.P.
Published: August 2013

Paget Disease of Bone is a disorder characterized by abnormal bone remodeling, associated with morphological and functional abnormalities of osteoclasts although its etiology remains unproven. Ion beam analysis (IBA) techniques may be useful to characterize the abnormal distribution and concentration of the major and trace elements that can be associated topagetic bone condition. In order to access the viability of this approach, healthy femoral head of cat has been investigated by Particle Induced X-Ray Emission (PIXE),Rutherford Backscattering Spectrometry (RBS) and Scanning Electron Microscopy (SEM).

The bone section was irradiated, under vacuum conditions, with a 2.0 MeV alpha particle beam produced by the 2.5 MV Van de Graaff Accelerator of CTN/IST (Lisbon, Portugal). An Oxford Microbeams-type nuclear microprobe was used (OM150 triplet system), which allowed the proton beam to be focused on the bone section with a spatial resolution of 3x4 µm2 and a mean beam current of ~90pA. The X-rays generated by the bone were recorded using an 80 mm2 Link X-ray detector (with a 145 eV energy resolution), that is positioned at 135º to the beam direction. The backscattered particles were collected by a 200 mm2 silicon surface barrier radiation detector with a 15 keV energy resolution that is positioned at 40º to the beam direction in a cornell geometry. SEM observations have been carried out with backscattered electrons (BSE) using a JEOL JSM 7001F microscope equipped with an INCA Oxford Instruments EDS spectrometer for point analyses and X-ray mapping. Standard petrographic procedures have been employed to prepare the samples for SEM observation: the specimens were partly encapsulated in epoxy resin, ground with 800 and 1000-grit SiC paper, polished with 6 μm and 1 μm diamond suspensions and coated with carbon.

A selected area of the sample has been scanned with the proton beam, allowing to generateelemental distribution maps for Ca and P (Figure 1). From X-line scans it was possible to extractline profiles of these elements. RBS and PIXE were used to determine the matrix and trace element composition in order to normalize the elemental concentrations. The results are shown in Table 1.Structural information on the Haversian Systems, includingbone lacunaeandosteocytes localization have been obtained by SEM (Figure 2).

The combination of these techniques proved to be a viable approach for the Pagetic bone characterization and will be used to analyze the structure of trabecular and cortical bones as well as the distribution and morphology of the pagetic bone cells, which can contribute to clarify the differences between pagetic and healthy bone.

V. Corregidor acknowledges the support from FCT-Ciência program. The work was also supported by FCT PEST-OE/CTM-UI0084/2011 grant.
Microscopy: A tool for quantitative pozzolanic activity in blended cements
Authors: Costa C. , Laginha I. , Carvalho P.A.
Published: August 2013

The reuse of waste fluid catalytic cracking (FCC) catalyst, from oil-refinery industry, as a partial substitute of cement is a promising way of reducing the environmental impact of cement production and, therefore, contributes for industrial sustainability. On the other hand partial replacement of cement by oil-cracking catalysts up to 10-15% (w/w) results in improved mechanical properties as the waste catalyst tends to react with Ca(OH)2 - liberated upon cement hydration - and forms additional strength-providing reaction products. Nevertheless, the pozzolanic reaction mechanisms between cement and the waste FCC catalyst, which involve Ca migration from the cementitious matrix into the FCC particles is still not well understood.

In the present study waste FCC catalyst has been incorporated in cement paste mortars with a 15:85 weight ratio. The microstructural evolution of the blended materials has been investigated by X-ray diffraction and scanning electron microscopy coupled with X-ray energy dispersive spectroscopy after curing times of 2, 7 and 28 days. Namely, the evolutions of the catalyst crystal structure and of the calcium content in the dispersed catalyst particles have been evaluated.

The results show that the Ca/(Si,Al) ratio in the catalyst particles tends to increase during the cure. However, the inward migration does not occur in a continuous front but rather tends to follow high-diffusivity paths resulting in Ca depleted rims (Fig. 1). On the other hand the presence of heavy metals resulting from oil-cracking (such as La) remains essentially unaltered after a cure of 28 days. The present study demonstrates that the diffusion of Ca from the surrounding cementitious matrix into the dispersed catalyst particles plays an important role in the pozzolanic activity of the system.

The authors acknowledge the funding by Fundação para a Ciência e Tecnologia through PTDC/ECM/113115/2009 and PEST-OE/CTM-UI0084/2011 grants.
Salt weathering of limestones: susceptibility of petrographical features (SEM study)
Authors: Alves C. , Figueiredo C. , Maurício A. , Aires-Barros L.
Published: August 2013

Salt weathering is one of the main processes affecting rock materials applied in the built environment. Scanning electron microscopy (SEM) studies can contribute to the understanding of the susceptibility of petrographic features of rocks to salt weathering.

SEM studies were performed in limestones (grainstones with the commercial designations of Semi-rijo and Moca Creme and a travertine) submitted to salt weathering tests (EN 12370 using sodium sulphate solutions and cubic specimens) consisting of 15 cycles of immersion/drying followed by water washing after the 15th cycle. Fragments from small cubes of the grainstones subjected to salt weathering cycles without the final water cleaning were also studied. SEM observation before and after the tests allows the discussion of the petrographical characteristics of these rocks that contribute to erosive decay under salt weathering.

In the case of the grainstones specimens the texture can be described in general as allochemical particles cemented by sparry calcite (Figure 1 a) and it is visible from the preparation of the polished surfaces the interface between the sparry cement and the allochemical components. After the salt weathering tests, SEM studies show (Figure 1 b) extensive fissuring in the sparry cement and separation between grains and sparry cement. Observations of disaggregation products showed an important amount of apparently intact grains. These results are similar to those observed by with the sparry cement being affect by salt crystallisation and lesser impact on the grains. Studies in the unwashed specimens showed the presence of sodium sulphate in the interface between allochemical grains and the sparry cement (Figure 1 c,d). Travertine specimens show heterogeneous patterns of erosion attributed to the heterogeneous texture of this rock, with more terrigenous (especially clay-rich) portions that favour a higher erosive susceptibility and the presence of clays has been frequently connected with salt weathering susceptibility in limestones. In Figure 1e can be observed the heterogeneity of a polished surface, with the more irregular portions showing a chemical spectra (Figure 1 f) indicative of the terrigenous component and the presence of sodium and sulphate (resulting from the solutions used in these weathering tests).

The authors acknowledge the support of the Fundação para a Ciência e Tecnologia (POCTI/CTA/44940/2002; PEst-OE/CTE/UI0697/2011 and Pest-OE/CTE/UI0098/2011, funding by the European Union and national budget of the Portuguese Republic). Acknowledgments to Eng. Teresa Luís, Eng. Sónia Pereira and Enterprise Mármores Galrão for the rock blocks.
Applications of Nuclear Techniques, Computer Simulation and Microscopy to Surface Analysis of Materials
Authors: Pacheco de Carvalho J. , Pacheco C.F.R. , Reis A.D.
Published: August 2013

There is a wide range of surface analysis techniques which are, generally, complementary. Nuclear and non-nuclear techniques have been available. Nuclear techniques, which are non-destructive, provide for analysis over a few microns close to the surface of the sample, giving absolute values of concentrations of isotopes and elements. They have been applied in areas such as scientific, technologic, industry, arts and medicine, using MeV ion beams. Nuclear reactions permit tracing of isotopes with high sensitivities. We use ion-ion nuclear reactions, elastic scattering and the energy analysis method where, at a chosen energy of the incident ion beam, an energy spectrum is recorded of ions from nuclear events, coming from several depths in the target. Such spectra are computationally predicted, giving target composition and concentration profile information. A computer program has been developed in this context, mainly for flat targets. The non-flat target situation arises as an extension. Successful applications of the method are given using the 18O(p,α0)15N reaction and elastic scattering of (4He)+ ions. SEM and TEM are used as useful complementary techniques.

Two types of samples were prepared containing thick and thin oxides, respectively. The first sample (S1) was obtained by high temperature oxidation of austenitic steel in C 18O2 gas. Weight gain measurements had given a 4.2 μm thick oxide. SEM has shown a reasonably flat oxide (Figure 1 (a)). The second sample (S2, also labelled Al/Al2O3) was obtained by anodization of high purity aluminium at 100V in an aqueous solution of ammonium citrate. An oxide thickness of 0.1370 μm was expected. TEM has given an oxide film thickness of 0.1340 μm (Figure 1 (b)). The 18O(p,α0)15N reaction at Ep=1.78 MeV and 165º was used to analyse sample S1. Figure 2 (a) shows a good computed fit to data. A 18O step concentration profile was found, corresponding to a thick 18O oxide with thickness X1=4.4 μm. Sample S2 was analysed by elastic scattering of α particles at Eα=2.0 MeV and 165º. Figure 2 (b) shows a good computed fit to data. A thin oxide film thickness of X1=0.1350 μm was found, close to the TEM value. The fit also shows a ratio of atomic densities of O and Al slightly above 1.5. The combined use of nuclear techniques, SEM and TEM microscopy has proved to be very important for surface analysis of materials. The reported results would be difficult to obtain by other techniques.

Supports from University of Beira Interior and FCT (Fundação para a Ciência e a Tecnologia)/PEst-OE/FIS/UI0524/2011 (Projecto Estratégico-UI524-2011-2012) are acknowledged.
SEM characterization of gelatin-ionic liquid functional polymers
Authors: Carvalho R.N.L. , Matias S.C. , Lourenço N.M.T. , Fonseca L.P.
Published: August 2013

ION JELLY® patented technology is based on the cross-linking of Ionic Liquids (ILs) with Gelatin that results in a viscous gel that can be molded into a film or a block, and solidifies by cooling below 35 ºC . The outcome of this combination is a transparent, light and flexible conductive polymer that adapts perfectly to a great variety of surfaces. Some of the key properties of ION JELLY® are: high stability up to 180ºC, large electrochemical window and bio-compatibility. Taking in consideration the attractive attributes of ILs, that provide a stable and friendly environment for the enzymes, where they retain their catalytic activity, combined with the morphologic advantage of gelatin, we have decided to study this new protein-ionic-based material regarding water content, swelling behaviour, and structural morphology by scanning electron microscopy (SEM).

The properties of [emim][EtSO4] and [bmim][N(CN)2] ION JELLY® films were compared with those of solely gelatin. Thin films were prepared with different amounts of water or phosphate buffer and left to maturate in a controlled atmosphere for 4 days. Swelling was carried out in water at 4ºC and films were lyophilized afterwards. SEM images of ION JELLY® and gelatin films were obtained prior and after these steps.

ION JELLY® films were rubbery while gelatin films were glassy. Water-made ION JELLY® had completely smooth surfaces, just like gelatin, but buffer-made ION JELLY® exhibited salt crystals on the surface, as well as some superficial pores (Figure 1). Free water content in [emim][EtSO4] ION JELLY® was found to be greater than [bmim][N(CN)2] ION JELLY® and gelatin.

The swelling ratio of both types of ION JELLY® was close to 100%, while gelatin swelled 8 times more. The swollen lyophilized gelatin films formed a heterogeneous and highly porous network (Figure 2), while ION JELLY® films were more homogeneous with a lower degree of porosity (Figure 3).

These results showed that ION JELLY® is a polymer with a more tightly bound structure than gelatin. This material allows water to penetrate, but possesses a higher rigidity that prevents too much mobility of the polymeric chains. Considering that it’s a biocompatible polymer, lyophilized swollen ION JELLY® could have potential applications as a scaffold for biological material.

Financial support received from the Portuguese Science and Technology foundation (Fundação para a Ciência e Tecnologia) under the grants SFRH/BD/77568/2011, PTDC/EBB-BIO/114288/2009, PTDC/EBB-BI/099237/2008 and SFRH/BPD/41175/2007 and Projecto Estratégico IBB: PEst – OE/EQB/LA0023/2011
Quantitative Analysis of Carbon in Silicon Carbide Coated with Carbon
Authors: Lee Hongrim , Kim Junsu , Yun Jondo
Published: August 2013

Nonconductive specimens for scanning electron microscopy or X-ray microanalysis are coated with conductive carbon in order to reduce charging. But carbon film absorbs X-ray fluxes causing errors in measuring chemical composition. Especially when the carbon content is measured, carbon coating not only blocks X-rays but also becomes a source of carbon X-rays. It is thus necessary to determine how much errors are induced by carbon coating, and how thick coating is allowed for the accurate measurement. In this study, quantitative analysis of carbon on silicon carbide with carbon coating films was attempted by electron probe microanalyzer. It was found that measured carbon content increased in a nonlinear manner up to 40% with a film thickness, whereas silicon content decreased slightly. Carbon X-ray intensity was determined by computer simulation, which increased in a linear manner with the thickness. The discrepancy was due to a nucleation and growth of islands and thus a change of density with a thickening of coating film.
Microstructure Characterization of ZK60 Magnesium Alloys Using TEM and HR-EBSD
Authors: Cho Jae-Hyung , Kim Soo-Hyun , Han Sang-Ho , Kang Suk-Bong
Published: August 2013

ZK60 (Mg–Zn–Zr) alloys exhibited a variation in precipitates with aging, and their mechanical properties also changed. Microindentation tests were carried out on two types of ZK60 alloys of solid solution (T4) and peak aging (T6). Microstructure and texture evolution during indentation was investigated using electron backscatter diffraction. Twinning occurred near the indentation marks in most grains. It was found that tensile twinning was dominant, and two twin variants were usually observed. Texture and microstructure evolution by twinning and slip activation was further examined by uniaxial compression test with strain. The initial random orientation gradually changed into basal fibers with strain. Some grains with nonbasal orientations aligned with the loading direction easily underwent twinning followed by slip deformation. Other grains near basal orientations revealed only slip deformation.
Phase Analysis on Dual-Phase Steel Using Band Slope of Electron Backscatter Diffraction Pattern
Authors: Kang Jun-Yun , Park Seong-Jun , Moon Man-Been
Published: August 2013

A quantitative and automated phase analysis of dual-phase (DP) steel using electron backscatter diffraction (EBSD) was attempted. A ferrite–martensite DP microstructure was produced by intercritical annealing and quenching. An EBSD map of the microstructure was obtained and post-processed for phase discrimination. Band slope (BS), which was a measure of pattern quality, exhibited much stronger phase contrast than another conventional one, band contrast. Owing to high sensitivity to lattice defect and little orientation dependence, BS provided handiness in finding a threshold for phase discrimination. Its grain average gave a superior result on the discrimination and volume fraction measurement of the constituent phases in the DP steel.
Statistical Analysis on Static Recrystallization Texture Evolution in Cold-Rolled AZ31 Magnesium Alloy Sheet
Authors: Park Jun-Ho , Ahn Tae-Hong , Choi Hyun-Sik , Chung Jung-Man , Kim Dong-Ik , Oh Kyu Hwan , Han Heung Nam
Published: August 2013

Cast AZ31B-H24 magnesium alloy, comprising Mg with 3.27 wt% Al and 0.96 wt% Zn, was cold rolled and subsequently annealed. Global texture evolutions in the specimens were observed by X-ray diffractometry after the thermomechanical processing. Image-based microstructure and texture for the deformed, recrystallized, and grown grains were observed by electron backscattered diffractometry. Recrystallized grains could be distinguished from deformed ones by analyzing grain orientation spread. Split basal texture of ca. ±10–15° in the rolling direction was observed in the cold-rolled sample. Recrystallized grains had widely spread basal poles at nucleation stage; strong {0001} basal texture developed with grain growth during annealing.
Amorphization Induced by Focused Ion Beam Milling in Metallic and Electronic Materials
Authors: Huh Yoon , Hong Ki Jung , Shin Kwang Soo
Published: August 2013

Focused ion beam (FIB) milling using high-energy gallium ions is widely used in the preparation of specimens for transmission electron microscopy (TEM). However, the energetic ion beam induces amorphization on the edge of specimens during milling, resulting in a mischievous influence on the clearness of high-quality transmission electron micrographs. In this work, the amorphization induced by the FIB milling was investigated by TEM for three kinds of materials, metallic materials in bulk shape, and semiconductive and electronic ceramic materials as a substrate for the deposition of thin films.
In Situ Transmission Electron Microscopy Imaging of Electromigration in Platinum Nanowires
Authors: Rudneva Maria , Gao Bo , Prins Ferry , Xu Qiang , van der Zant Herre S.J. , Zandbergen Henny W.
Published: August 2013

In situ transmission electron microscopy was performed on the electromigration in platinum (Pt) nanowires (14 nm thick, 200 nm wide, and 300 nm long) with and without feedback control. Using the feedback control mode, symmetric electrodes are obtained and the gap usually forms at the center of the Pt nanowire. Without feedback control, asymmetric electrodes are formed, and the gap can occur at any position along the wire. The three-dimensional gap geometries of the electrodes in the Pt nanowire were determined using high-angle annular dark-field scanning transmission electron microscopy; the thickness of the nanowire is reduced from 14 nm to only a few atoms at the edge with a gap of about 5–10 nm.
In Situ Heating Transmission Electron Microscopy Observation of Nanoeutectic Lamellar Structure in Sn–Ag–Cu Alloy on Au Under-Bump Metallization
Authors: Seo Jong-Hyun , Yoon Sang-Won , Kim Kyou-Hyun , Chang Hye-Jung , Lee Kon-Bae , Seong Tae-Yeon , Fleury Eric , Ahn Jae-Pyoung
Published: August 2013

We investigated the microstructural evolution of Sn96.4Ag2.8Cu0.8 solder through in situ heating transmission electron microscopy observations. As-soldered bump consisted of seven layers, containing the nanoeutectic lamella structure of AuSn and Au5Sn phases, and the polygonal grains of AuSn2 and AuSn4, on Au-plated Cu bond pads. Here, we found that there are two nanoeutectic lamellar layers with lamella spacing of 40 and 250 nm. By in situ heating above 140°C, the nanoeutectic lamella of AuSn and Au5Sn was decomposed with structural degradation by sphering and coarsening processes of the lamellar interface. At the third layer neighboring to the lamella layer, on the other hand, Au5Sn particles with a zig-zag shape in AuSn matrix became spherical and were finally dissipated in order to minimize the interface energy between two phases. In the other layers except both lamella layers, polycrystal grains of AuSn2 and AuSn4 grew by normal grain growth during in situ heating. The high interface energy of nanoeutectic lamella and polygonal nanograins, which are formed by rapid solidification, acted as a principal driving force on the microstructural change during the in situ heating.
Electron Holography Study of the Charging Effect in Microfibrils of Sciatic Nerve Tissues
Authors: Kim Ki Hyun , Akase Zentaro , Shindo Daisuke , Ohno Nobuhiko , Fujii Yasuhisa , Terada Nobuo , Ohno Shinichi
Published: August 2013

The charging effects of microfibrils of sciatic nerve tissues due to electron irradiation are investigated using electron holography. The phenomenon that the charging effects are enhanced with an increase of electron intensity is visualized through direct observations of the electric potential distribution around the specimen. The electric potential at the surface of the specimen could be quantitatively evaluated by simulation, which takes into account the reference wave modulation due to the long-range electric field.
The Effects of Maintaining Temperature in Annealing Heat Treatment for an FSWed 6061-T6 Al Alloy
Authors: Lee Seung-Jun , Han Min-Su , Kim Seong-Jong
Published: August 2013

The technological development of all kinds of lightweight transportation devices including vehicles, aircraft, ships, etc. has progressed markedly with the demand for energy saving and environmental protection. Aluminum alloy is in the spotlight as it is a suitable environmentally friendly material. However, deformation is a major problem during the welding process because aluminum alloy has a large thermal expansion coefficient. In addition, it is known that its corrosion resistance is excellent; nevertheless, in practice, considerable corrosion is generated and this is a major problem. To solve this problem, the friction stir welding (FSW) technology is applied extensively at various industrial fields as a new welding technique. This method involves a process in which materials are joined by frictional heat and physical force. Therefore, we evaluated improvements in mechanical properties and corrosion resistance through annealing heat treatment after FSW. The electrochemical experiment did not show a significant difference. However, the microstructure observation showed defectless, fine crystal particles, indicating excellent properties at 200–225°C.
An Investigation on the Optimum Corrosion Protection Potential for Minimization of Cavitation Damage Using the Potentiostatic Method in Seawater
Authors: Kim Seong-Jong , Jang Seok-Ki , Park Jae-Cheul
Published: August 2013

In this study, we replaced the expensive blade material with an aluminum–bronze alloy that has excellent corrosion resistance and cavitation characteristics and developed the corrosion protection method to improve durability using an electrochemical method. The objective of this study was to identify the electrochemical corrosion protection conditions to minimize cavitation damage due to generating hydrogen gas (2H2O + 2e− → 2OH− + H2) by means of hydrogen overvoltage before the impact pressure of the cavity is transferred to the surface. In the constant potential experiment under the cavitation environment, the energy was reflected or cancelled out by collision of the cavities with the hydrogen gas generated by the hydrogen overvoltage. As a result, the optimal corrosion prevention potential in the dynamic state is assumed to be the range of −1.4 to −1.7 V, which is the range at which active polarization took place.
Scale-Bridging Analysis on Deformation Behavior of High-Nitrogen Austenitic Steels
Authors: Lee Tae-Ho , Ha Heon-Young , Hwang Byoungchul , Kim Sung-Joon , Shin Eunjoo , Lee Jong Wook
Published: August 2013

Scale-bridging analysis on deformation behavior of high-nitrogen austenitic Fe–18Cr–10Mn–(0.39 and 0.69)N steels was performed by neutron diffraction, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM). Two important modes of deformation were identified depending on the nitrogen content: deformation twinning in the 0.69 N alloy and strain-induced martensitic transformation in the 0.39 N alloy. The phase fraction and deformation faulting probabilities were evaluated based on analyses of peak shift and asymmetry of neutron diffraction profiles. Semi in situ EBSD measurement was performed to investigate the orientation dependence of deformation microstructure and it showed that the variants of ε martensite as well as twin showed strong orientation dependence with respect to tensile axis. TEM observation showed that deformation twin with a {111}⟨112⟩ crystallographic component was predominant in the 0.69 N alloy whereas two types of strain-induced martensites (ε and α′ martensites) were observed in the 0.39 N alloy. It can be concluded that scale-bridging analysis using neutron diffraction, EBSD, and TEM can yield a comprehensive understanding of the deformation mechanism of nitrogen-alloyed austenitic steels.
Microstructural Study on Kirkendall Void Formation in Sn-Containing/Cu Solder Joints During Solid-State Aging
Authors: Liu Zhi-Quan , Shang Pan-Ju , Tan Feifei , Li Douxing
Published: August 2013

Kirkendall void formation at the solder/metallization interface is an important reliability concern for Cu conductors and under-bump metallization in microelectronic packaging industry, whose mechanism is still hard to be understood for different individual cases. In the present work, two typical solder/Cu-diffusing couples, eutectic SnIn/Cu and SnBi/Cu, were studied by scanning/transmission electron microscopy to investigate the microstructural evolution and voiding process after soldering and then solid-state aging. It was concluded that Kirkendall voids formed between two sublayers within Cu2(In,Sn) phase in eutectic SnIn/Cu solder joint, whereas they appeared at the Cu3Sn/Cu interface or within Cu3Sn for eutectic SnBi/Cu solder joint. Besides the effect of impurity elements, the morphological difference within one intermetallic compound layer could change the diffusing rates of reactive species, hence resulting in void formation in the reaction zone.
Identification of Local Phase of Nanoscale BaTiO3 Powders by High-Resolution Electron Energy Loss Spectroscopy
Authors: Moon Sun-Min , Wang Xiaohui , Cho Nam-Hee
Published: August 2013

The electron energy loss spectroscopy (EELS) technique was applied to investigate the local variation in the phase of barium titanate (BaTiO3) ceramics. It was found that the fine structure of the titanium L2,3 edge and their satellite peaks were sensitively varied with the tetragonal–cubic phase transition. The peak splitting of Ti-L3 edge of tetragonal-phased BaTiO3 ceramics was widened because of the increased crystal field effect compared with that of cubic-phased BaTiO3. In case of nanoscale BaTiO3 powders, the L3 edge splitting of the core region was found to be smaller than that of the shell region. The energy gap between peaks t2g and eg varied from 2.36 to 1.94 eV with changing the probe position from 1 to 20 nm from the surface. These results suggest that the EELS technique can be used to identify the local phase of sintered BaTiO3 ceramics.
Interfacial Structure and Electrical Properties of Transparent Conducting ZnO Thin Films on Polymer Substrates
Authors: Lim Young Soo , Kim Dae Wook , Kang Jong-Ho , Seo Seul Gi , Kim Bo Bae , Choi Hyoung-Seuk , Seo Won-Seon , Cho Yong Soo , Park Hyung-Ho
Published: August 2013

The effects of polymer substrates on the interfacial structure and the thermal stability of Ga-doped ZnO (GZO) thin films were investigated. The GZO thin films were deposited on polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrates by rf-magnetron sputtering at room temperature, and thermal stability tests of the GZO thin films on the polymer substrates were performed at 150°C up to 8 h in air. Electrical and structural characterizations of the GZO thin films on the PET and the PEN substrates were carried out, and the origins of the stable interfacial structure and the improved thermal stability of the GZO thin film on the PEN substrate were discussed.
Analytical Electron Microscopy of W-Core β-SiC Fibers for Use in an SiC-Based Composite Material for Fusion Applications
Authors: Toplišek Tea , Gec Medeja , Iveković Aljaž , Novak Saša , Kobe Spomenka , Dražić Goran
Published: August 2013

In this work, the interactions between tungsten (W) and silicon carbide (SiC) in SigmaTM SiC fibers at high temperatures were characterized using scanning and transmission electron microscopy. These fibers could have the potential for use in fusion-related applications owing to their high thermal conductivity compared with pure SiC-based fibers. The as-received fibers were composed of a 100-μm-thick shell of radially textured β-SiC grains and a 15-μm-thick tungsten core, composed of a few hundreds of nm-sized elongated tungsten grains. The interfaces between the tungsten and the SiC and the SiC and the outer coatings were sharp and smooth. After heat treatment at 1,600°C for 3 h in Ar, the tungsten core reacted with SiC to form a rough interface surface. Inside the core, W5Si3, W3Si, and W2C phases were detected using energy-dispersive X-ray spectroscopy and electron-diffraction techniques. The mechanical properties of the fibers deteriorate after the heat treatment.
Provenance Study through Analysis of Microstructural Characteristics Using an Optical Microscope and Scanning Electron Microscopy for Goryeo Celadon Excavated from the Seabed
Authors: Min-su Han
Published: August 2013

This paper aims at identifying the provenance of Goryeo celadons by understanding its microstructural characteristics, such as particles, blisters, forms and amount of pores, and the presence of crystal formation, bodies, and glazes and its boundary, using an optical microscope and scanning electron microscopy (SEM). The analysis of the reproduced samples shows that the glazed layer of the sherd fired at higher temperatures has lower viscosity and therefore it encourages the blisters to be combined together and the layer to become more transparent. In addition, the result showed that the vitrification and melting process of clay minerals such as feldspars and quartzs on the bodies was accelerated for those samples. To factor such characteristics of the microstructure and apply it to the sherds, the samples could be divided into six categories based on status, such as small particles with many small pores or mainly large and small circular pores in the bodies, only a limited number of varied sized blisters in the glazes, and a few blisters and needle-shaped crystals on the boundary surface. In conclusion, the analysis of the microstructural characteristics using an optical microscope and SEM have proven to be useful as a categorizing reference factor in a provenance study on Goryeo celadons.