scholarly journals Two-Dimensional Zeolite Materials: Structural and Acidity Properties

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1822 ◽  
Author(s):  
Emily Schulman ◽  
Wei Wu ◽  
Dongxia Liu
Keyword(s):  
Single Unit ◽  
Active Sites ◽  
Three Dimensional ◽  
Total Surface Area ◽  
Unit Cell ◽  
Future Research ◽  
Two Dimensional ◽  
Beneficial Effects ◽  
Surface Areas ◽  
Composition Properties

Zeolites are generally defined as three-dimensional (3D) crystalline microporous aluminosilicates in which silicon (Si4+) and aluminum (Al3+) are coordinated tetrahedrally with oxygen to form large negative lattices and consequent Brønsted acidity. Two-dimensional (2D) zeolite nanosheets with single-unit-cell or near single-unit-cell thickness (~2–3 nm) represent an emerging type of zeolite material. The extremely thin slices of crystals in 2D zeolites produce high external surface areas (up to 50% of total surface area compared to ~2% in micron-sized 3D zeolite) and expose most of their active sites on external surfaces, enabling beneficial effects for the adsorption and reaction performance for processing bulky molecules. This review summarizes the structural properties of 2D layered precursors and 2D zeolite derivatives, as well as the acidity properties of 2D zeolite derivative structures, especially in connection to their 3D conventional zeolite analogues’ structural and compositional properties. The timeline of the synthesis and recognition of 2D zeolites, as well as the structure and composition properties of each 2D zeolite, are discussed initially. The qualitative and quantitative measurements on the acid site type, strength, and accessibility of 2D zeolites are then presented. Future research and development directions to advance understanding of 2D zeolite materials are also discussed.

scholarly journals Three-Dimensional Thematic Map Imaging of the Yacht Port on the Example of the Polish National Sailing Centre Marina in Gdańsk

2021 ◽  
Vol 11 (15) ◽  
pp. 7016
Author(s):  
Pawel S. Dabrowski ◽  
Cezary Specht ◽  
Mariusz Specht ◽  
Artur Makar
Keyword(s):  
Spatial Data ◽  
Convex Surface ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Future Research ◽  
Two Dimensional ◽  
Thematic Maps ◽  
Research Directions ◽  
Future Research Directions ◽  
The Many

The theory of cartographic projections is a tool which can present the convex surface of the Earth on the plane. Of the many types of maps, thematic maps perform an important function due to the wide possibilities of adapting their content to current needs. The limitation of classic maps is their two-dimensional nature. In the era of rapidly growing methods of mass acquisition of spatial data, the use of flat images is often not enough to reveal the level of complexity of certain objects. In this case, it is necessary to use visualization in three-dimensional space. The motivation to conduct the study was the use of cartographic projections methods, spatial transformations, and the possibilities offered by thematic maps to create thematic three-dimensional map imaging (T3DMI). The authors presented a practical verification of the adopted methodology to create a T3DMI visualization of the marina of the National Sailing Centre of the Gdańsk University of Physical Education and Sport (Poland). The profiled characteristics of the object were used to emphasize the key elements of its function. The results confirmed the increase in the interpretative capabilities of the T3DMI method, relative to classic two-dimensional maps. Additionally, the study suggested future research directions of the presented solution.

Three isostructural solvates of a tetrahydrofurochromenone derivative

2017 ◽  
Vol 73 (5) ◽  
pp. 407-413 ◽  
Author(s):  
Balasubramanian Sridhar ◽  
Jagadeesh Babu Nanubolu ◽  
Krishnan Ravikumar ◽  
Govindaraju Karthik ◽  
Basi Venkata Subba Reddy
Keyword(s):  
Three Dimensional ◽  
Unit Cell ◽  
Multicomponent Systems ◽  
Two Dimensional ◽  
The Core ◽  
Cell Dimensions ◽  
Similarity Indices ◽  
Unit Cell Dimensions ◽  
Similar Unit ◽  
Crystal Packings

Isostructurality is more likely to occur in multicomponent systems. In this context, three closely related solvates were crystallized, namely, benzene (C27H21BrO6·C6H6), toluene (C27H21BrO6·C7H8) and xylene (C27H21BrO6·C8H10) with methyl 3a-acetyl-3-(4-bromophenyl)-4-oxo-1-phenyl-3,3a,4,9b-tetrahydro-1H-furo[3,4-c]chromene-1-carboxylate, and their crystal structures determined. All three structures belong to the same space group (P\overline{1}) and display similar unit-cell dimensions and conformations, as well as isostructural crystal packings. The isostructurality is confirmed by unit-cell and isostructural similarity indices. In each solvate, weak C—H...O and C—H...π interactions extend the molecules into two-dimensional networks, which are further linked by C—H...Br and Br...Br interactions into three-dimensional networks. The conformation of the core molecule is predominantly responsible for governing the isostructurality.

scholarly journals Two-dimensional crystals formed from photosynthetic reaction centers.

1983 ◽  
Vol 97 (4) ◽  
pp. 1266-1270 ◽  
Author(s):  
K R Miller ◽  
J S Jacob
Keyword(s):  
Electron Microscopy ◽  
Single Unit ◽  
Reaction Centers ◽  
Unit Cell ◽  
Two Dimensional ◽  
Photosynthetic Reaction Centers ◽  
Photosynthetic Membranes ◽  
Fourier Techniques ◽  
High Degree ◽  
Degree Of Order

Photosynthetic reaction centers from the bacterium Rhodopseudomonas viridis were prepared after detergent solubilization of photosynthetic membranes. The purified reaction centers, in agreement with reports from other laboratories, contain four distinct polypeptides ranging in molecular weight from 28,000 to 41,000. When the detergent was gradually removed by dialysis under appropriate conditions, large two-dimensional sheets of reaction centers were formed, suitable for analysis by electron microscopy. The crystals were rectangular, and the dimensions of a single unit cell were 121 X 129 A. Each unit cell contained four distinct subunits, each with approximate dimensions of 45 X 60 A. The thickness of the sheet was 60 A. Preliminary studies of the sheets with negative staining indicated that the sheets show a high degree of order: as many as six orders are visible in transforms of the images. Because of the fact that in R. viridis the native membrane from which these reaction centers were purified also displays a crystal-like structure, comparative studies between a membrane and one of its components, each analyzed by Fourier techniques, are now possible.

scholarly journals Two-Dimensional Frank-Kasper Z Phase with One Unit-Cell Thickness

2020 ◽  
Author(s):  
Xie Hongbo ◽  
Junyuan Bai ◽  
Haiyan Ren ◽  
Shanshan Li ◽  
Hucheng Pan ◽  
...  
Keyword(s):  
Density Functional ◽  
Three Dimensional ◽  
Volume Ratio ◽  
Dark Field ◽  
Unit Cell ◽  
Two Dimensional ◽  
Cell Height ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

Abstract Z phase is one of the three basic units by which the Frank-Kasper phases are generally assembled. Compared to the other two basic units, i.e., A15 and C15 structures, the Z phase structure is rarely experimentally observed because of a relatively large volume ratio among the constituents to inhibit its formation. Moreover, the discovered Z structures are generally the three-dimensional (3D) ordered Gibbs bulk phases to conform to their thermodynamic stability. Herein, we confirmed the existence of a metastable two-dimensional (2D) Frank-Kasper Z phase with one unit-cell height in the crystallography in a model Mg-Sm-Zn system, by using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) combined with density functional theory (DFT) calculations. This finding is important for understanding the relationship between the traditional crystal structures and the quasicrystals, and it is also expected to provide a new insight to understand the clustering and stacking behavior of atoms in condensed matters.

Fluoride sensing performance of fluorescent NH2-MIL-53(Al): 2D Nanosheets vs. 3D Bulk

2021 ◽  
Author(s):  
Zixuan Li ◽  
Deyi Zhan ◽  
Abdul Saeed ◽  
Nanjing Zhao ◽  
Junfeng Wang ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Active Sites ◽  
Metal Organic Frameworks ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Metal Organic ◽  
2D Nanosheets ◽  
Fluoride Sensing ◽  
Sensing Performance

Due to the ultra-thin morphology, larger specific surface area and more exposed active sites, two-dimensional (2D) metal-organic frameworks (MOFs) nanosheets can break the limitations of three-dimensional (3D) MOFs in sensitivity,...

Mechanical Properties of Open-Cell Cellular Structures With Rhombic Dodecahedron Cells

2010 ◽  
Author(s):  
Sahab Babaee ◽  
Babak Haghpanah Jahromi ◽  
Amin Ajdari ◽  
Hamid Nayeb-Hashemi ◽  
Ashkan Vaziri
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Single Unit ◽  
Cellular Structure ◽  
Three Dimensional ◽  
Small Deformation ◽  
Unit Cell ◽  
Analytical Models ◽  
Open Cell ◽  
Principal Directions

We present a series of analytical models and finite element results (FE) for special 3-D open cellular foam to determine the effective material properties of a 3D rhombic dedecahedron open-cell cellular structure. The analytical approach is based on minimizing the total energy associated with small deformation of a single unit cell of the cellular structure. The finite element models were developed for both a single unit cell and three dimensional foam structure and used to obtain the mechanical properties in all three principal directions.

scholarly journals Analyzing Femorotibial Cartilage Thickness Using Anatomically Standardized Maps: Reproducibility and Reference Data

2021 ◽  
Vol 10 (3) ◽  
pp. 461
Author(s):  
Julien Favre ◽  
Hugo Babel ◽  
Alessandro Cavinato ◽  
Katerina Blazek ◽  
Brigitte M. Jolles ◽  
...  
Keyword(s):  
Reference Data ◽  
Three Dimensional ◽  
Cartilage Thickness ◽  
Future Research ◽  
Two Dimensional ◽  
Resonance Imaging ◽  
Magnetic Resonance Imaging Mri ◽  
Operator Reproducibility ◽  
Mesh Models ◽  
And Cartilage

Alterations in cartilage thickness (CTh) are a hallmark of knee osteoarthritis, which remain difficult to characterize at high resolution, even with modern magnetic resonance imaging (MRI), due to a paucity of standardization tools. This study aimed to assess a computational anatomy method producing standardized two-dimensional femorotibial CTh maps. The method was assessed with twenty knees, processed following three common experimental scenarios. Cartilage thickness maps were obtained for the femorotibial cartilages by reconstructing bone and cartilage mesh models in tree-dimension, calculating three-dimensional CTh maps, and anatomically standardizing the maps. The intra-operator accuracy (median (interquartile range, IQR) of −0.006 (0.045) mm), precision (0.152 (0.070) mm), entropy (7.02 (0.71) and agreement (0.975 (0.020))) results suggested that the method is adequate to capture the spatial variations in CTh and compare knees at varying osteoarthritis stages. The lower inter-operator precision (0.496 (0.132) mm) and agreement (0.808 (0.108)) indicate a possible loss of sensitivity to detect differences in a setting with multiple operators. The results confirmed the promising potential of anatomically standardized maps, with the lower inter-operator reproducibility stressing the need to coordinate operators. This study also provided essential reference data and indications for future research using CTh maps.

scholarly journals Recent Advances in Three-Dimensional Stem Cell Culture Systems and Applications

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xiaowen Wu ◽  
Junxiang Su ◽  
Jizhen Wei ◽  
Nan Jiang ◽  
Xuejun Ge
Keyword(s):  
Cell Culture ◽  
Culture System ◽  
Three Dimensional ◽  
Culture Method ◽  
Future Research ◽  
Two Dimensional ◽  
Culture Methods ◽  
Three Dimensional Culture ◽  
Dimensional Cell

Cell culture is one of the most core and fundamental techniques employed in the fields of biology and medicine. At present, although the two-dimensional cell culture method is commonly used in vitro, it is quite different from the cell growth microenvironment in vivo. In recent years, the limitations of two-dimensional culture and the advantages of three-dimensional culture have increasingly attracted more and more attentions. Compared to two-dimensional culture, three-dimensional culture system is better to realistically simulate the local microenvironment of cells, promote the exchange of information among cells and the extracellular matrix (ECM), and retain the original biological characteristics of stem cells. In this review, we first present three-dimensional cell culture methods from two aspects: a scaffold-free culture system and a scaffold-based culture system. The culture method and cell characterizations will be summarized. Then the application of three-dimensional cell culture system is further explored, such as in the fields of drug screening, organoids and assembloids. Finally, the directions for future research of three-dimensional cell culture are stated briefly.

scholarly journals HDlive in the Assessment of Fetal Intracranial, Intrathoracic and Intra-abdominal Anomalies

2014 ◽  
Vol 8 (4) ◽  
pp. 362-375 ◽  
Author(s):  
Toshiyuki Hata
Keyword(s):  
Obstet Gynecol ◽  
Three Dimensional ◽  
3D Ultrasound ◽  
Future Research ◽  
Cystic Lesions ◽  
Two Dimensional ◽  
Fetal Anomalies ◽  
Inversion Mode ◽  
Innovative Tool

ABSTRACT We present a series of images of different fetal intracranial, intrathoracic and intra-abdominal anomalies reconstructed using HDlive. It is a novel three-dimensional (3D) ultrasound modality that can provide the operator with naturally realistic features of any fetal anomalies. HDlive and its inversion mode are applied in several cases and two-dimensional (2D) sonographic images of different anomalies are also presented clearly to compare the advantages of HDlive in this article. This review focuses on the role of HDlive in the presence of such anomalies. HDlive should be a very useful aid in adjunct to other ultrasound modalities, specifically in cases that warrant detailed information. It can also be useful for the antenatal surveillance of anomalies, such as cystic lesions that may progress to complications. This innovative tool offers many promising advantages in clinical practice and future research on fetal anomalies. How to cite this article Cajusay-Velasco S, Hata T. HDlive in the Assessment of Fetal Intracranial, Intrathoracic and Intraabdominal Anomalies. Donald School J Ultrasound Obstet Gynecol 2014;8(4):362-375.

Sign in / Sign up

Export Citation Format

Share Document