Microwave synthesis of high-quality and uniform 4 nm ZnFe₂O₄ nanocrystals for application in energy storage and nanomagnetics

• Christian Suchomski,
• Ben Breitung,
• Ralf Witte,
• Michael Knapp,
• Sondes Bauer,
• Tilo Baumbach,
• Christian Reitz and
• Torsten Brezesinski

Beilstein J. Nanotechnol. 2016, 7, 1350–1360, doi:10.3762/bjnano.7.126

• shape of the ZFO nanoparticles was investigated by means of transmission electron microscopy (TEM). The low-magnification bright-field TEM image in Figure 1a shows that they are spherical in shape with a narrow size distribution around 4 nm. Both high-resolution TEM (HRTEM, Figure 1b) and selected-area

• conclude that the particles are of good quality and thus hold promise for application in various fields of nanotechnology. Electron microscopy of as-prepared ZFO nanoparticles. (a) Bright-field TEM image. (b) HRTEM image and (c) SAED pattern demonstrating the crystallinity. Note that only the most intense

High performance Ce-doped ZnO nanorods for sunlight-driven photocatalysis

• Bilel Chouchene,
• Tahar Ben Chaabane,
• Lavinia Balan,
• Emilien Girot,
• Kevin Mozet,
• Ghouti Medjahdi and
• Raphaël Schneider

Beilstein J. Nanotechnol. 2016, 7, 1338–1349, doi:10.3762/bjnano.7.125

• some irregular cylindrical structures developed. The high crystallinity of the particles is further evident from the HRTEM image (Figure 6) and from the selected area electron diffraction (SAED) patterns shown in the insets of Figure 5. The bright and clear diffraction spots belong to the single

• crystal ZnO rods. From the HRTEM image (Figure 6a), one can clearly observe the crystal planes of ZnO. The interplanar spacing of ZnO is of ca. 0.26 nm, corresponding well to the (002) plane of ZnO. For 5, 7 and 10% doping in Ce, the ZnO rods were found to coexist with a significantly reduced population

• of small ellipsoidal CeO2 particles with an average diameter of ca. 5 nm deposited at the surface of the rods (Figure 6b), forming CeO2/ZnO:Ce heterostructures. The analysis of the interplanar distance calculated from the HRTEM image shows the (111) plane of cubic ceria. The BET surface area of pure

Fabrication and characterization of branched carbon nanostructures

• Sharali Malik,
• Yoshihiro Nemoto,
• Hongxuan Guo,
• Katsuhiko Ariga and
• Jonathan P. Hill

Beilstein J. Nanotechnol. 2016, 7, 1260–1266, doi:10.3762/bjnano.7.116

• MWCNTs, namely Baytubes©. Other workers have shown using high resolution transmission electron microscopy (HRTEM) that Baytubes© are parallel-walled in long closed sections and that they are strong and relatively pure [27]. They form around a catalyst and are supplied as loosely agglomerated pellets

• , which results in the introduction of defects that later act as the “unzipping” points. The procedure has the additional benefit of cleaning the tubes as substantiated from the Raman (Figure 2d) and HRTEM data (Figure 3) confirming the absence of carbon impurities or residual catalyst material. The

• (Renishaw inVia), TEM (Tecnai F20 ST at 200 kV), HRTEM (Jeol ARM at 120 kV), SEM (Zeiss Ultra-Plus at 5 kV), SEM (Zeiss Leo 1530 at 10 kV with Oxford X-Max 50 EDX ) and helium ion microscopy (HeIM, Zeiss Orion at 30 kV). a) SEM overview of a Baytubes agglomerated pellet; b, c) SEM details of the MWCNTs; d

Tunable longitudinal modes in extended silver nanoparticle assemblies

• Serene S. Bayram,
• Klas Lindfors and
• Amy Szuchmacher Blum

Beilstein J. Nanotechnol. 2016, 7, 1219–1228, doi:10.3762/bjnano.7.113

• . Figure 4 presents a HRTEM image for two nanoparticles interacting through their [111] facets. The image reveals two major facets of nanoparticles under study, [111] and [200], with predominance of the former. A HRTEM image showing the [200] facet spacings is presented in Figure S5 (Supporting Information

• nanoparticle facets were determined after HRTEM imaging using the lattice constant of silver (0.408 nm). The as-prepared samples were freshly plated on 200 mesh carbon-coated copper grids (Canemco-Marivac, Lakefield, QC) with a carbon film thickness ranging between 30 and 50 nm for 5 min before wicking using

• the stronger coupling. TEM micrographs of AgNPs modified by increasing ratios r of DTT and cysteamine ligands. Images show typical aggregates formed at the given ligand ratio. HRTEM image of AgNPs ensembles. The distance shown in the image corresponds to 10 × d. Here, d is the inter-planar distance

Fast diffusion of silver in TiO₂ nanotube arrays

• Wanggang Zhang,
• Yiming Liu,
• Diaoyu Zhou,
• Hui Wang,
• Wei Liang and
• Fuqian Yang

Beilstein J. Nanotechnol. 2016, 7, 1129–1140, doi:10.3762/bjnano.7.105

• treatment. From the HRTEM (high-resolution TEM) analysis shown in Figure 3c, a width of 3.52 Å between neighboring lattice fringes is observed in agreement with the (101) lattice spacing of anatase TiO2 [30][31]. This result reveals the highly crystalline nature of the TiO2 nanotubes in accord with the SAED

• . This result suggests that Ag was not oxidized during the heat treatment. The (111), (200), (220) and (311) crystal planes of cubic Ag are observed, in good accord with the XRD analysis. The HRTEM image shown in Figure 7c depicts the characteristic lattice fringe of 3.52 Å for TiO2 nanotubes and 2.36 Å

• image of the pure TiO2 nanotubes, (b) SAED pattern showing the presence of TiO2 nanocrystals, and (c) HRTEM image of a pure TiO2 nanotube. XRD patterns of TiO2 nanotube arrays with Ag nanofilm heat treated at three different temperatures for different periods of time. SEM images of the TiO2 nanotube

Multiwalled carbon nanotube hybrids as MRI contrast agents

• Nikodem Kuźnik and
• Mateusz M. Tomczyk

Beilstein J. Nanotechnol. 2016, 7, 1086–1103, doi:10.3762/bjnano.7.102

• polyelectrolytes could also be observed in the TEM images [33]. High resolution TEM (HRTEM) and X-ray diffraction (XRD) revealed the crystalline structure of the nanoparticles and enabled qualitative identification of the elements (e.g., lanthanides and silicon in EuGdLa/SiO2/PAH/MWCNT#Chen) and their structural

Photocurrent generation in carbon nanotube/cubic-phase HfO₂ nanoparticle hybrid nanocomposites

• Protima Rauwel,
• Augustinas Galeckas,
• Martin Salumaa,
• Frédérique Ducroquet and
• Erwan Rauwel

Beilstein J. Nanotechnol. 2016, 7, 1075–1085, doi:10.3762/bjnano.7.101

• the point-to-point resolution was ≈1 Å in STEM mode. High resolution transmission electron microscopy (HRTEM) carried out on the same microscope at 200 kV provided a point-to-point resolution of 2.4 Å. Electron energy loss spectroscopy (EELS) was acquired in STEM mode with an Enfinium spectrometer at

• at buckled edges of the MWCNT, (f) wall of the nanotube showing defects and irregularities to which nanoparticles are attached, (g) HRTEM images of randomly oriented agglomerates, (h) <110>-oriented, and (i) <001>-oriented nanoparticles indicated by arrows and all attached to curved regions of the

Microscopic characterization of Fe nanoparticles formed on SrTiO₃(001) and SrTiO₃(110) surfaces

• Miyoko Tanaka

Beilstein J. Nanotechnol. 2016, 7, 817–824, doi:10.3762/bjnano.7.73

• ). Some of these structures are aligned along the or the directions of STO and presumably have OR2 orientation. Other nanoparticles just have irregular shapes and are thought to exhibit multiple orientations. HRTEM observation in a profile-view mode disclosed nanoparticles of major and of other

High-resolution noncontact AFM and Kelvin probe force microscopy investigations of self-assembled photovoltaic donor–acceptor dyads

• Benjamin Grévin,
• Pierre-Olivier Schwartz,
• Laure Biniek,
• Martin Brinkmann,
• Nicolas Leclerc,
• Elena Zaborova and
• Stéphane Méry

Beilstein J. Nanotechnol. 2016, 7, 799–808, doi:10.3762/bjnano.7.71

• beam was blanked with a shutter and a nearby area was selected to record the HRTEM image. Image treatment was performed by using the AnalySIS software (Soft Imaging System). Results and Discussion Surface morphology Figure 4a,b shows the surface morphology of AD1 and AD3 films after in situ annealing

Facile synthesis of water-soluble carbon nano-onions under alkaline conditions

• Gaber Hashem Gaber Ahmed,
• Rosana Badía Laíño,
• Josefa Angela García Calzón and
• Marta Elena Díaz García

Beilstein J. Nanotechnol. 2016, 7, 758–766, doi:10.3762/bjnano.7.67

• leaves (acer saccharum), under the same temperature and alkaline conditions did not produce carbon onions. XRD, FTIR, HRTEM, UV–vis spectroscopy, and photoluminescence analyses were performed to characterize the as-synthesized carbon nanomaterials. Preliminary tests demonstrate a capability of the

• characteristics of these structures the formation mechanism of C-onions is proposed. Finally, a preliminary test on the use of such C-onions as sensing materials for metal ions is outlined. Results and Discussion In Figure 1a the HRTEM image reveals that the tomato C-dots synthetized by conventional carbonization

• are mostly spherical, with diameters well below 1 nm as also can be observed for C-dots from tree leaves (Figure 1c). In Figure 1b, the HRTEM image shows that C-dots from carrots are also spherical but with diameters around 5 nm. When using a NaOH 30% (w/v) media the C-NPs exhibited a different

Orientation of FePt nanoparticles on top of a-SiO₂/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size

• Martin Schilling,
• Paul Ziemann,
• Zaoli Zhang,
• Johannes Biskupek,
• Ute Kaiser and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2016, 7, 591–604, doi:10.3762/bjnano.7.52

• electron microscopy (HRTEM) after different annealing steps between 200 and 650 °C. The L10 phase is obtained at annealing temperatures above 550 °C for films and 600 °C for nanoparticles in accordance with previous reports. On the amorphous surface of a-SiO2/Si substrates we find no preferential

• transmission electron microscopy (HRTEM); nanoparticles; reflection high-energy electron diffraction (RHEED); solid-phase epitaxy; texture; Introduction Due to their attractive catalytic properties for oxygen reduction reactions (ORR) [1][2] as well as their high magnetocrystalline anisotropy energy density

• coalescence, growth or Ostwald ripening by annealing can be completely avoided [15]. In the present study we investigate the possibility of a structural (re)orientation of FePt NPs and thin films on a-SiO2/Si(001), MgO(001), and sapphire(0001) after different in situ annealing steps by HRTEM and RHEED

In situ observation of deformation processes in nanocrystalline face-centered cubic metals

• Aaron Kobler,
• Christian Brandl,
• Horst Hahn and
• Christian Kübel

Beilstein J. Nanotechnol. 2016, 7, 572–580, doi:10.3762/bjnano.7.50

• diffracting volume, which is encoded in the diffraction pattern and peak profile. For a local analysis, NC metals are traditionally investigated using bright/dark field transmission electron microscopy (BF/DF-TEM) [31][32][33] or high resolution TEM (HRTEM) [34]. In situ BF/DF-TEM deformation experiments are

• behavior for different alloy compositions [28][48]. In situ XRD studies also showed evidence on the concentration-dependent deformation behavior in the Pd–Au alloy [49]. Despite the good grain statistics of ACOM-TEM in comparison to HRTEM, synchrotron-based in situ XRD studies offer better temporal

Early breast cancer screening using iron/iron oxide-based nanoplatforms with sub-femtomolar limits of detection

• Dinusha N. Udukala,
• Hongwang Wang,
• Sebastian O. Wendel,
• Aruni P. Malalasekera,
• Thilani N. Samarakoon,
• Asanka S. Yapa,
• Gayani Abayaweera,
• Matthew T. Basel,
• Pamela Maynez,
• Raquel Ortega,
• Yubisela Toledo,
• Leonie Bossmann,
• Colette Robinson,
• Katharine E. Janik,
• Olga B. Koper,
• Ping Li,
• Massoud Motamedi,
• Daniel A. Higgins,
• Gary Gadbury,
• Gaohong Zhu,
• Deryl L. Troyer and
• Stefan H. Bossmann

Beilstein J. Nanotechnol. 2016, 7, 364–373, doi:10.3762/bjnano.7.33

• provided in the text. TEM (1a,1b) and HRTEM (1c) images of Fe/Fe3O4-core/shell nanoparticles that are forming the inorganic core of the nanoplatforms for protease detection, with permission from [20], copyright 2014 Royal Society of Chemistry. HRTEM images revealed that the Fe(0) centers are mostly

Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures

• Tuan Anh Pham,
• Andreas Schreiber,
• Elena V. Sturm (née Rosseeva),
• Stefan Schiller and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2016, 7, 351–363, doi:10.3762/bjnano.7.32

• NPs arranged in linear chains (Figure 8C,D). In contrast to the Au NPs, which give a higher TEM contrast, no clear NP separation could be observed between the individual NPs. However, the interparticle distance of the Fe3O4 NPs in the high resolution TEM (HRTEM) image in Figure S6, Supporting

• protein cavity. Additionally, artefacts, such as drying effects during the TEM sample preparation, can also decrease the interparticle distance. In order to evaluate the orientational relationship between the iron oxide NPs within the assembled fiber-like structure, HRTEM images were recorded with a large

• field of view. Figure 9A illustrates one of the HRTEM images (“snapshot”) which was used to determine the orientation of magnetite along the 1D chain by evaluation of fast Fourier transforms (FFT) of individual NPs. Since the synthetic magnetite NPs are quite inhomogeneous in morphology, for

Sonochemical co-deposition of antibacterial nanoparticles and dyes on textiles

• Ilana Perelshtein,
• Anat Lipovsky,
• Nina Perkas,
• Tzanko Tzanov and
• Aharon Gedanken

Beilstein J. Nanotechnol. 2016, 7, 1–8, doi:10.3762/bjnano.7.1

• h under agitation at 100 rpm. The leaching solutions were analyzed by ICP-OES for the presence of ions. The release of NPs into the saline was examined by a high-resolution transmission electron microscope (HRTEM), JEOL, operated at 200 kV. The difference in colorization of the textiles before and

• subjected to HRTEM measurements. The results did not reveal the presence of NPs on the grid, indicating that nanoparticles are not released from the coated surface, confirming their strong adherence onto the surface. A total loss in the range of 2.5–12.2% of the metal oxides was found. This loss is due to

Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver nanoparticles

• Dulce G. Romero-Urbina,
• Humberto H. Lara,
• J. Jesús Velázquez-Salazar,
• M. Josefina Arellano-Jiménez,
• Eduardo Larios,
• Anand Srinivasan,
• Jose L. Lopez-Ribot and
• Miguel José Yacamán

Beilstein J. Nanotechnol. 2015, 6, 2396–2405, doi:10.3762/bjnano.6.246

• induced by AgNPs, which were investigated using various electron microscopy techniques, such as high resolution transmission electron microscopy (HRTEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), scanning electron microscopy (SEM), and energy dispersive X-ray

Surfactant-controlled composition and crystal structure of manganese(II) sulfide nanocrystals prepared by solvothermal synthesis

• Elena Capetti,
• Anna M. Ferretti,
• Vladimiro Dal Santo and
• Alessandro Ponti

Beilstein J. Nanotechnol. 2015, 6, 2319–2329, doi:10.3762/bjnano.6.238

• of both). The rock salt structure of MnS NCs was confirmed by HRTEM: Figure 2a displays lattice fringes separated by 0.258 nm that correspond to the {200} planes of the α-MnS structure. The geometric phase analysis (GPA) [31] showed that the NCs are single crystallites, almost free from lattice

• diffraction patterns. Selected ED patterns and TEM images are displayed in Figure 4. The identification of the crystal structure and the crystalline quality of the MnS NCs was confirmed by HRTEM images (Figure 2b). The crystal structure of the resulting NCs is summarized in Table 1 along with the

• Conventional transmission electron microscopy (TEM) images (medium resolution), high resolution TEM (HRTEM) images and electron diffraction (ED) patterns were recorded by a Zeiss LIBRA 200FE-HR TEM. The samples for microscopy were prepared by evaporating a drop of the nanocrystal dispersion in hexane on a

A single-source precursor route to anisotropic halogen-doped zinc oxide particles as a promising candidate for new transparent conducting oxide materials

• Daniela Lehr,
• Markus R. Wagner,
• Johanna Flock,
• Julian S. Reparaz,
• Clivia M. Sotomayor Torres,
• Alexander Klaiber,
• Thomas Dekorsy and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2015, 6, 2161–2172, doi:10.3762/bjnano.6.222

• HRTEM (scalebar 10 nm) of the ZnO1−xClx material. See also Figure S4 (Supporting Information File 1). (a) Absorption spectra in diffuse reflection modus, room temperature photoluminescence spectra; overview (b) and band gap region (c). (d) PL spectra recorded at T = 7 K. Hashes (blue): ZnO (Dcryst = 22

Selective porous gates made from colloidal silica nanoparticles

• Roberto Nisticò,
• Paola Avetta,
• Paola Calza,
• Debora Fabbri,
• Giuliana Magnacca and
• Dominique Scalarone

Beilstein J. Nanotechnol. 2015, 6, 2105–2112, doi:10.3762/bjnano.6.215

• then calcined using the same conditions applied for the coating preparation (400 °C for 2 h, ramp of 2 °C/min). Silica powders thus obtained were analyzed by HRTEM to verify that their morphology was identical to that of thin spin-coated films obtained from the same micellar solution. Physicochemical

• characterization Transmission electron microscopy (HRTEM) was used to evaluate the morphology of colloidal silica nanoparticle coatings after the removal of the templates. Micrographs were obtained by using a JEOL JEM 2010 instrument (300 kV) equipped with a LaB6 filament. For the specimen preparation a few drops

Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials

• Xiaoxing Ke,
• Carla Bittencourt and
• Gustaaf Van Tendeloo

Beilstein J. Nanotechnol. 2015, 6, 1541–1557, doi:10.3762/bjnano.6.158

• HRTEM is expressed by Equation 1 [25]. A quantitative description of different lens aberrations in electron microscopy has been extensively discussed in the literature [24]. where λ is the wavelength of the electrons and C3 is the third-order spherical aberration coefficient of the objective lens. It

• reduction of the resolving power. Using a multi-walled carbon nanotube (MWCNT) for demonstration, a high resolution TEM (HRTEM) image acquired at 200 kV using a conventional FEI Tecnai G2 microscope is shown in Figure 2a, where the spatial resolution is about 1.5 Å. When the accelerating voltage is lowered

• , HRTEM on defect-free graphene at 100 kV causes damage to the sample, including pentagons, heptagons and octagons [35]. The experimental results clearly show that a Td of 23 eV and 22 eV (corresponding to an incident beam of approx. 110 kV) is overestimated. Such a difference may indicate that the

Thermal treatment of magnetite nanoparticles

• Beata Kalska-Szostko,
• Urszula Wykowska,
• Dariusz Satula and
• Per Nordblad

Beilstein J. Nanotechnol. 2015, 6, 1385–1396, doi:10.3762/bjnano.6.143

• treated as single crystals, have been obtained. This can be seen in HRTEM studies [49]. Therefore, oxide penetration is hampered and becomes much slower. The stepwise decomposition of the Fe(acac)3 complex causes the presence of grain-like growth of each subsequent layer. This introduces many more grain

Influence of the shape and surface oxidation in the magnetization reversal of thin iron nanowires grown by focused electron beam induced deposition

• Luis A. Rodríguez,
• Lorenz Deen,
• Rosa Córdoba,
• César Magén,
• Etienne Snoeck,
• Bert Koopmans and
• José M. De Teresa

Beilstein J. Nanotechnol. 2015, 6, 1319–1331, doi:10.3762/bjnano.6.136

• microstructure were determined by bright field (BF) TEM and high resolution TEM (HRTEM) imaging, and chemical composition of the sections was determined by combining high angle annular dark field (HAADF) imaging and electron energy loss spectroscopy (EELS) in scanning transmission electron microscopy (STEM) mode

• parameters obtained from Figure 3d (half profile) and establishing z0 as the tNom of the nanowires. The HRTEM images of the nanowires, shown in Figure S3 (Supporting Information File 1), indicate that the Fe is nanocrystalline, as previously reported [14][18]. This microstructure will produce negligible

Heterometal nanoparticles from Ru-based molecular clusters covalently anchored onto functionalized carbon nanotubes and nanofibers

• Deborah Vidick,
• Xiaoxing Ke,
• Michel Devillers,
• Claude Poleunis,
• Arnaud Delcorte,
• Pietro Moggi,
• Gustaaf Van Tendeloo and
• Sophie Hermans

Beilstein J. Nanotechnol. 2015, 6, 1287–1297, doi:10.3762/bjnano.6.133

• microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) confirms their bimetal nature on the nanoscale. The obtained bimetal nanoparticles supported on nanocarbon were tested as catalysts in ammonia synthesis and are shown to be active at low temperature

• on the size of nanoparticles obtained than the choice of the initial nanocarbon material. HRTEM and HAADF-STEM studies In order to further study the structure of the supported Ru–Pt nanoparticles, the sample supported on MWNTs derived from Ru5PtC(CO)14(COD) (4) is characterized by high resolution

• transmission electron microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) using aberration-corrected transmission electron microscopy (AC-TEM). HRTEM images of nanoparticles derived from cluster 4 reveal that they are not well crystallized (Figure 4a

High photocatalytic activity of V-doped SrTiO₃ porous nanofibers produced from a combined electrospinning and thermal diffusion process

• Panpan Jing,
• Wei Lan,
• Qing Su and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 1281–1286, doi:10.3762/bjnano.6.132

• SrTiO3 nanofibers, which is consistent with the results from the SEM image. Moreover, Figure 1f displays a HRTEM image of V-doped SrTiO3. The average fringe spacing was measured to be about 1.42 Å which is larger than the 1.38 Å of the (220) plane of standard SrTiO3. Correlating these XRD results, it

• be filled by oxygen, owing to balance between the positive and negative charges. The lattice of the V-doped SrTiO3 increases and is larger than that of pure SrTiO3, which is similar with the result observed from XRD and HRTEM. Hence, it is concluded that V-doped SrTiO3 nanofibers were successfully

• using field emission scanning electron microscopy (FESEM, Hitachi S-4800) and transmission electron microscopy (TEM, TecnaiTM G2F30, FEI), X-ray diffraction (XRD, Cu Kα, λ = 1.5406 Å), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS, Kratos AXIS

The convenient preparation of stable aryl-coated zerovalent iron nanoparticles

• Olga A. Guselnikova,
• Andrey I. Galanov,
• Anton K. Gutakovskii and
• Pavel S. Postnikov

Beilstein J. Nanotechnol. 2015, 6, 1192–1198, doi:10.3762/bjnano.6.121

• a 10 nm thick organic layer to provide long-term protection in air for the highly reactive zerovalent iron core up to 180 °C. The surface-modified iron NPs possess a high grafting density of the aryl group on the NPs surface of 1.23 mmol/g. FTIR spectroscopy, XRD, HRTEM, TGA/DTA, and elemental

• ). In the darkfield image, the nanocrystals are indicated by bright areas. In the high-resolution transmission electron microscopy (HRTEM) image, the atomic planes of the iron crystal lattice are clearly visualized. The NPs are mostly uniform in size with an average core particle diameter of 21 nm with

• °C/min under a flow of air at 80 mL/min. HRTEM observations were performed on a JEM-4000EX (JEOL) electron microscope. Elemental analysis was acquired with a Leco 628 carbon/hydrogen/nitrogen analyzer. The specific surface area was measured using a Micromeritics Tristar II 3020 surface area analyzer