Magnesiothermic conversion of the silica-mineralizing golden algae Mallomonas caudata and Synura petersenii to elemental silicon with high geometric precision

• Janina Petrack,
• Steffen Jost,
• Jens Boenigk and
• Matthias Epple

Beilstein J. Nanotechnol. 2014, 5, 554–560, doi:10.3762/bjnano.5.65

• and hierarchical forms [8][9][10][11][12]. These porous biominerals can serve as template for chemical conversion reactions, such as the calcium carbonate skeleton of sea urchins or the silica cases of diatoms [8][13]. In 2002, such a conversion reaction was first described in which biominerals were

• template are possible. The deposition of gold or silver coatings on diatom frustules by thermal evaporation has been described [8]. Sandhage et al. have shown that diatom structures can be chemically converted at higher temperature, e.g., with magnesium to magnesium oxide or with calcium to calcium oxide

• spectroscopy (EDX) of the golden algae before the conversion are shown in Figure 4. Besides silicon, a couple of other elements were detected. The carbon and gold signals are due to the carbon sample holder and the gold sputtering, but the elements oxygen, sodium, magnesium, sulfur, calcium, and iron were

Neutral and charged boron-doped fullerenes for CO₂ adsorption

• Suchitra W. de Silva,
• Aijun Du,
• Wijitha Senadeera and
• Yuantong Gu

Beilstein J. Nanotechnol. 2014, 5, 413–418, doi:10.3762/bjnano.5.49

• , heterofullerenes also offer excellent tuneable chemical and physical properties [10]. Gas adsorption on heterofullerenes is an appealing subject. B. Gao et al. [11] studied CO2 adsorption on calcium decorated C60 fullerene and F. Gao et al. [12] studied O2 adsorption on nitrogen-doped fullerene. Boron-doped C60

Change of the work function of platinum electrodes induced by halide adsorption

• Florian Gossenberger,
• Tanglaw Roman,
• Katrin Forster-Tonigold and
• Axel Groß

Beilstein J. Nanotechnol. 2014, 5, 152–161, doi:10.3762/bjnano.5.15

• combination of charge transfer and polarization effects on the adsorbate layer. The results are contrasted to the adsorption of fluorine on calcium, a system in which a decrease in the work function is also observed despite a large charge transfer to the halogen adatom. Keywords: density functional theory

• obtained for fluorine adsorption on calcium, for which an adsorption-induced decrease of the work function is also observed. However, due to the particular geometric conditions in this system, the spillout mechanism [8][22] is operative. Methods For the following calculations, the periodic density

• with increasing adsorption coverage [9][40], similar to the work function plot of F on Pt in the current study. Fluorine on calcium We have shown that the strong polarizability of large atoms such as iodine leads to a considerable buildup of charge in the adatom–surface bonding regions, which is

Exploring the retention properties of CaF₂ nanoparticles as possible additives for dental care application with tapping-mode atomic force microscope in liquid

• Matthias Wasem,
• Joachim Köser,
• Sylvia Hess,
• Enrico Gnecco and
• Ernst Meyer

Beilstein J. Nanotechnol. 2014, 5, 36–43, doi:10.3762/bjnano.5.4

• very interesting for application in science, technology and medical applications including dentistry [18]. In this context calcium fluoride is of high interest in saliva chemistry and in the context of reducing acid dissolution of teeth [19]. The outermost layer of the teeth, also called enamel, has

• upon exposure to a fluorated solution has been observed with AFM in liquid [26]. To the best of our knowledge no manipulation experiment of particles adsorbed on human tooth enamel has been performed so far. The anticaries activity of calcium fluoride nanoparticles is mainly determined by two factors

• adhesion strength of calcium fluoride nanoparticles adsorbed on mica and on tooth enamel in liquid with AM-AFM. Theory As already described above, manipulation experiments in the tapping-mode are difficult to quantify as dynamic and friction processes are involved at the same time. To connect the power

Surface assembly and nanofabrication of 1,1,1-tris(mercaptomethyl)heptadecane on Au(111) studied with time-lapse atomic force microscopy

• Tian Tian,
• Burapol Singhana,
• Lauren E. Englade-Franklin,
• Xianglin Zhai,
• T. Randall Lee and
• Jayne C. Garno

Beilstein J. Nanotechnol. 2014, 5, 26–35, doi:10.3762/bjnano.5.3

• dried with calcium hydride (CaH2) and distillated before use. Pyridinium chlorochromate (PCC) and lithium aluminum hydride (LiAlH4) were purchased from Alfa Aesar. 1-Octadecanol (ReagentPlus®, 99%), formaldehyde (37 wt % in H2O), trifluoromethanesulfonic anhydride (≥99%), 18-crown-6 (≥99.9%), pyridine

Nano-FTIR chemical mapping of minerals in biological materials

• Sergiu Amarie,
• Paul Zaslansky,
• Yusuke Kajihara,
• Erika Griesshaber,
• Wolfgang W. Schmahl and
• Fritz Keilmann

Beilstein J. Nanotechnol. 2012, 3, 312–323, doi:10.3762/bjnano.3.35

• inorganic particles embedded in organic matrices [15][16][17]. Major tissues of interest include the phosphatic (bone) family of materials, and the carbonatic family as found, e.g., in mollusc shells. Within the phylum Brachiopoda, both strategies of hybrid shell architecture have evolved: Calcium carbonate

• crystals in an organic matrix [18][19][20], and laminates of calcium phosphate nanoparticle reinforced chitin fibers [21][22]. FTIR spectroscopic microscopy is a well-established method and has been extensively used to study bone biominerals at several micrometers spatial resolution [23][24][25][26][27][28

• shown in Figure 5). The spectra in Figure 3b and Figure 3c (and also the extracted averaged spectral profiles in Figure 4) are dominated by a single, sharp resonance, which differs in frequency position for orthorhombic aragonite (855 cm−1) and trigonal calcite (873 cm−1), and thus both calcium

Detection of interaction between biomineralising proteins and calcium carbonate microcrystals

• Hanna Rademaker and
• Malte Launspach

Beilstein J. Nanotechnol. 2011, 2, 222–227, doi:10.3762/bjnano.2.26

• brittle calcium carbonate mineral platelets embedded in a mechanically weak organic layer, nature has created a tough material. For recent reviews dealing with biomineralisation and especially nacre consult [2] and [3]. The fracture resistance of the whole shell and especially nacre, which consists of

• unspecific binding seems unlikely, since lanes A and C (Figure 4) show no difference in intensity. Verification of a specific binding would be most interesting, because this would be evidence that protein–mineral interaction guide polymorph selection and morphology of the calcium carbonate crystals. This

• on the molecular to atomic scale and conducting further experiments. Experimental As we stated several times above, the detection of interaction between biomineralising proteins and calcium carbonate microcrystals in this study is based on a modified approach from [1]. The main differences between