Hyperspectral interference tomography of nacre

Structural characterization of biologically formed materials is essential for understanding biological phenomena and their enviro-nment, and for generating new bio-inspired engineering concepts. For example, nacre—the inner lining of some mollusk shells—encodes local environmental conditions throughout its formation and has exceptional strength due to its nanoscale brick-and-mortar structure. This layered structure, comprising alternating transparent aragonite (CaCO3) tablets and thinner organic polymer layers, also results in stunning interference colors. Existing methods of structural characterization of nacre rely on some form of cross-sectional analysis, such as scanning or transmission electron microscopy or polarization-dependent imaging contrast (PIC) mapping. However, these techniques are destructive and too time- and resource-intensive to analyze large sample areas. Here, we present an all-optical, rapid, and nondestructive imaging technique—hyperspectral interference tomography (HIT)—to spatially map the structural parameters of nacre and other disordered layered materials. We combined hyperspectral imaging with optical-interference modeling to infer the mean tablet thickness and its disorder in nacre across entire mollusk shells from red and rainbow abalone (Haliotis rufescens and Haliotis iris) at various stages of development. We observed that in red abalone, unexpectedly, nacre tablet thickness decreases with age of the mollusk, despite roughly similar appearance of nacre at all ages and positions in the shell. Our rapid, inexpensive, and nondestructive method can be readily applied to in-field studies.

Download Full-text

Chemical and Structural Characterization of Maize Stover Fractions in Aspect of Its Possible Applications

Materials ◽

10.3390/ma14061527 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1527

Author(s):

Magdalena Woźniak ◽

Izabela Ratajczak ◽

Dawid Wojcieszak ◽

Agnieszka Waśkiewicz ◽

Kinga Szentner ◽

...

Keyword(s):

Structural Characterization ◽

Biogas Production ◽

Structural Parameters ◽

C:N Ratio ◽

Crystallinity Index ◽

Degree Of Crystallinity ◽

Cellulose Content ◽

X Ray Diffraction ◽

Maize Stover

In the last decade, an increasingly common method of maize stover management is to use it for energy generation, including anaerobic digestion for biogas production. Therefore, the aim of this study was to provide a chemical and structural characterization of maize stover fractions and, based on these parameters, to evaluate the potential application of these fractions, including forbiogas production. In the study, maize stover fractions, including cobs, husks, leaves and stalks, were used. The biomass samples were characterized by infrared spectroscopy (FTIR), X-ray diffraction and analysis of elemental composition. Among all maize stover fractions, stalks showed the highest C:N ratio, degree of crystallinity and cellulose and lignin contents. The high crystallinity index of stalks (38%) is associated with their high cellulose content (44.87%). FTIR analysis showed that the spectrum of maize stalks is characterized by the highest intensity of bands at 1512 cm−1 and 1384 cm−1, which are the characteristic bands of lignin and cellulose. Obtained results indicate that the maize stover fraction has an influence on the chemical and structural parameters. Moreover, presented results indicate that stalks are characterized by the most favorable chemical parameters for biogas production.

Download Full-text

Crystallographic and structural characterization of heterometallic platinum compounds Part VII. Heterohepta- and heterooctanuclear clusters

Open Chemistry ◽

10.1515/chem-2015-0035 ◽

2014 ◽

Vol 13 (1) ◽

Author(s):

Milan Melnik ◽

Peter Mikuš ◽

Clive E. Holloway

Keyword(s):

Structural Characterization ◽

Structural Parameters ◽

Bond Distance ◽

Point Of View ◽

Platinum Compounds ◽

Metal Atoms ◽

Platinum Clusters ◽

Structural Point

AbstractThis review classifies and analyzes over fifty heterohepta- and heterooctanuclear platinum clusters. There are eight types of metal combinations in heteroheptanuclear: Pt6M, Pt5M2, Pt4M3, Pt3M4, Pt2M5, PtM6, Pt3Hg2Ru2 and Pt2Os3Fe2. The seven metal atoms are in a wide variety of arrangements, with the most common being one in which the central M atom (mostly M(I)) is sandwiched by two M3 triangles. Another arrangement often found is an octahedron of M6 atoms asymmetrically capped by an M atom. The shortest Pt-M bond distances (non-transition and transition) are 2.326(1) Å (M = Ga) and 2.537(6) Å (M = Fe). The shortest Pt-Pt bond distance is 2.576(2) Å.In heterooctanuclear platinum clusters there are eight types of metal combinations: Pt6M2, Pt4M4, Pt3Ru5, Pt2M6, PtM7, Pt2W4Ni2, PtAu6Hg and PtAu5Hg2. From a structural point of view, the clusters are complex with bicapped octahedrons of eight metal atoms prevailing. The shortest Pt-M bond distances (non-transition and transition) are 2.651(3) Å (M = Hg) and 2.624(1) Å (M = Os). The shortest Pt-Pt bond distance is 2.622(1) Å. These values are somewhat longer than those in the heteroheptanuclear clusters. Several relationships between the structural parameters were found, and are discussed and compared with the smaller heterometallic platinum clusters

Download Full-text

Crystallographic and structural characterization of heterometallic platinum complexes Part V. Heteropentanuclear complexes

Open Chemistry ◽

10.2478/s11532-013-0382-5 ◽

2014 ◽

Vol 12 (3) ◽

pp. 283-306 ◽

Cited By ~ 2

Author(s):

Milan Melník ◽

Peter Mikuš ◽

Clive Holloway

Keyword(s):

Structural Characterization ◽

Structural Parameters ◽

Bond Distance ◽

Platinum Complexes ◽

Trigonal Bipyramidal ◽

Metal Atoms ◽

Independent Molecules

AbstractThis review classifies and analyzes over eighty heteropentanuclear Pt complexes. There are eight types of metal combinations: Pt4M, Pt3M2, Pt2M3, PtM4, Pt3MM′, Pt2M2M′, PtM2M′2 and PtM3M′. The five metal atoms are in a wide variety of arrangements: trigonal-bipyramidal (most common), square-pyramidal, spike-triangular, butterfly, cubane, linear and one unique. Platinum bonds to a variety of triad partner metal atoms, soft, through borderline to hard. The shortest Pt-M bond distances for non-transition and transition M are 2.406(4) Å (M = Ge) and 2.30(1) Å (M = Co). The shortest Pt-Pt bond distance is 2.580(1) Å. Several relationships between the structural parameters were found and are discussed. Several complexes exist in two isomeric forms and others contain two crystallographically independent molecules. Both the isomers as well as independent molecules are examples of distortion isomerism.

Download Full-text

Solvothermal synthesis and structural characterization of a three-dimensional metal–organic polymer [NaZn(1,2,4-BTC)] (1,2,4-BTC=1,2,4-benzenetricarboxylate)

Solid State Sciences ◽

10.1016/j.solidstatesciences.2003.11.002 ◽

2004 ◽

Vol 6 (1) ◽

pp. 85-90 ◽

Cited By ~ 27

Author(s):

Lei Wang ◽

Zhan Shi ◽

Guanghua Li ◽

Yong Fan ◽

Wensheng Fu ◽

...

Keyword(s):

Structural Characterization ◽

Solvothermal Synthesis ◽

Three Dimensional ◽

Organic Polymer ◽

Metal Organic

Download Full-text

Expert System for Structural Characterization of Phyllosilicates: II. Application to Mixed-Layer Minerals

Clay Minerals ◽

10.1180/claymin.1994.029.1.05 ◽

1994 ◽

Vol 29 (1) ◽

pp. 39-45 ◽

Cited By ~ 4

Author(s):

V. A. Drits ◽

A. Plançon

Keyword(s):

Expert System ◽

Mixed Layer ◽

Structural Characterization ◽

Structural Parameters ◽

Margin Of Error ◽

Xrd Patterns

AbstractThe expert system described in the first part of this paper has been applied to the identification of mixed-layer phyllosilicates (mica-smectite, mica-vermiculite, chlorite-smectite, chlorite-vermiculite, chlorite-swelling chlorite, chlorite-mica, chlorite-talc, kaolinite-smectite, talc-smectite), and to the determination of their structural parameters (Reichweite, R, and proportions of constituting layers, Wi). The expert system has been run utilizing the data extracted from (1) experimental XRD patterns for which structural parameters had been evaluated by comparison with calculated patterns, or (2) patterns calculated using pre-selected values of the structural parameters. In all cases examined, the expert system provided correct conclusions concerning the identification of a mixed-layer phyllosilicate and the value of the Reichweite, while the abundances of the component layers were evaluated with a margin of error usually <5%.

Download Full-text

STRUCTURAL CHARACTERIZATION OF CO-PRECIPITATED Cd1-xZnxS:Cu CRYSTALS

International Journal of Modern Physics B ◽

10.1142/s0217979202008099 ◽

2002 ◽

Vol 16 (03) ◽

pp. 481-496 ◽

Cited By ~ 4

Author(s):

ABDUL NAYEEM ◽

K. YADAIAH ◽

G. VAJRALINGAM ◽

P. MAHESH ◽

M. NAGABHOOSHANAM

Keyword(s):

Grain Size ◽

Dislocation Density ◽

Internal Stress ◽

Lattice Constant ◽

Structural Characterization ◽

Structural Parameters ◽

Size Variation ◽

Preferred Orientation ◽

Average Internal Stress

Structural characterization of Cd 1-x Zn x S : Cu solid solutions were carried out with 0≤x≤1. XRD studies have revealed that the compounds are polycrystalline in nature having either Hexagonal (wurtzite) or Cubic (Zincblende) structure irrespective of their composition. Also the compounds have shown the most preferred reflections due to the plane [101] of CdS(H) and [111] of ZnS(C) in addition to other prominent reflections. The various structural parameters such as lattice constant, average internal stress, micro strain, dislocaion density, grain size, and preferred orientation were correlated with the composition. The lattice constant decreased linearly with the increase in Zn concentration. The sign of internal stress indicated elongational and compressional natures corresponding to hexagonal and cubic phases of CdS respectively. The variation of micro strain appeared to be conjugate when compared to grain size variation, and the variation of dislocation density with the composition showed a higher dislocation density till x=0.4 and then decreased till x=0.8 and then increased. The degree of preferred orientation in mixed Cd 1-x Zn x S : Cu crystals as observed by the maximum peak intensity of CdS(H) and ZnS(C) reflection showed that the degree of preferred orientation remained almost constant till x=0.6 and then increased. The results were explained on the basis of different phases of the compound and the defects related to Zn atoms.

Download Full-text

Structural Characterization of GaP/GaAs/GaP Heterostructure by TEM

MRS Proceedings ◽

10.1557/proc-280-449 ◽

1992 ◽

Vol 280 ◽

Author(s):

G. Aragón ◽

S. I. Molina ◽

R. García

Keyword(s):

Buffer Layer ◽

Structural Characterization ◽

Defect Structure ◽

Gaas Substrate ◽

Density Difference ◽

Interface Plane ◽

Cross Sectional ◽

Fringe Contrast ◽

Gaas Buffer Layer

ABSTRACTThe defect structure in a GaP/GaAs/GaP heterostructure deposited on a (001) GaAs substrate with a GaAs buffer layer has been characterized by cross sectional TEM. The buffer layer presents dislocations and (α-δ)-fringe contrast parallel to (001) interface plane. HREM study reveals uniformly distributed amorphous capsules in the first GaP/GaAs buffer layer interface. The dominant defects are microtwins which are propagated into the overall heterostructure. Microtwin density is different in the GaP and GaAs layers.The different stress signs may explain the density difference.

Download Full-text

Crystallographic and structural characterization of heterometallic platinum compounds part IV: heterotetranuclear clusters

Open Chemistry ◽

10.2478/s11532-013-0320-6 ◽

2013 ◽

Vol 11 (12) ◽

pp. 1902-1953 ◽

Cited By ~ 3

Author(s):

Milan Melník ◽

Peter Mikuš ◽

Clive Holloway

Keyword(s):

Structural Characterization ◽

Structural Parameters ◽

Platinum Compounds ◽

Metal Atoms ◽

Platinum Clusters

AbstractThis review includes over two hundred heterotetranuclear platinum clusters. The clusters are of the compositions Pt3M, Pt3M2, PtM3, Pt′2MM′, PtM2M′ and PtMM′M”. There are twenty five different M atoms (transition and non-transition) as a partner(s) of platinum. The four metal atoms are found in a tetrahedral, planar-rhombohedral, butterfly, spited-triangular, cubane, eight — and oligo-membered rings and a unique structures. There is wide variety of the ligands from uni to- undecadentate, with the most common P and C donor sites. The shortest Pt-M (transition) versus Pt-M (non-transition) bond distances are 2.4833(8)Å (M=Pd) vs. 2.4365(5)Å (Ge). Several relationships between the various structural parameters were found and are discussed.

Download Full-text

Cross‐sectional structural characterization of the surface of exfoliated HOPG using HRTEM‐EELS

Surface and Interface Analysis ◽

10.1002/sia.6875 ◽

2020 ◽

Vol 53 (1) ◽

pp. 84-89

Author(s):

Kun'ichi Miyazawa ◽

Takuro Nagai ◽

Koji Kimoto ◽

Masaru Yoshitake ◽

Yumi Tanaka

Keyword(s):

Structural Characterization ◽

Cross Sectional

Download Full-text

Crystallographic and structural characterization of heterometallic platinum clusters Part VIII. Heteronona- and heterodecanuclear clusters

Open Chemistry ◽

10.1515/chem-2015-0053 ◽

2014 ◽

Vol 13 (1) ◽

Author(s):

Milan Melník ◽

Peter Mikuš ◽

Clive E. Holloway

Keyword(s):

Structural Characterization ◽

Structural Parameters ◽

Platinum Atom ◽

Metal Bond ◽

Metal Atoms ◽

Metal Metal ◽

Platinum Clusters ◽

Metal Composition ◽

Independent Molecules

AbstractThis review classifies and analyses fifty heteronona- and heterodecanuclear Pt clusters of metal composition: Pt4Ru5, Pt3Ru6, Pt20sr PtRh8, PtAu8; Pt6M4, Pt5M5, Pt4M6, Pt3M2, Pt2M8, PtM9, Pt3Ru6M and PtAu8M. There are nine different heterometals: M = Ru, Au, Ag, Cu, Hg, Os, Rh, Ir and Fe, of which Ru and Au are the most frequent. The clusters crystallize mostly into two crystal classes, monoclinic (74%) and triclinic (18%), and their structures are complex. Three triangular layers of nine metal atoms arranged in the form of a face-shared bioctahedron are common in the series of heterononanuclear clusters. In the series of heterodecanuclear clusters distorted skeletal icosahedrons, where a central platinum atom is surrounded by nine metal atoms, and face (edge) shared (fused) bioctahedral cluster of the metal atoms are the most common. The most frequent ligands are CO and PPh3. The shortest metal-metal bond distances are: 2.540(4) Å (Pt-Fe), 2.580(2) Å (Ru-Ru), 2.584 Å (Pt-Pt) and 2.629(4) Å (Cu-Au). Several relationships between the structural parameters were found and are discussed. Some clusters contain two crystallographically independent molecules within the same crystal and are examples of distortion isomerism.

Download Full-text