Vertical Positioning of Internal Molecular Scaffolding within a Single Molecular Layer

1998 ◽  
Vol 102 (47) ◽  
pp. 9550-9556 ◽  
Author(s):  
Henning Menzel ◽  
Mark D. Mowery ◽  
Mei Cai ◽  
Christine E. Evans
Keyword(s):  
Molecular Layer ◽  
Vertical Positioning ◽  
Single Molecular Layer

The Adsorption Characteristics and Mechanism of Pb(II) onto Corn Straw Biochar

2021 ◽  
Vol 15 (3) ◽  
pp. 287-295
Author(s):  
Liucheng Wang ◽  
Huanhuan Zhao ◽  
Xianglin Song ◽  
Yake Li ◽  
Dong Li
Keyword(s):  
Molecular Layer ◽  
Corn Straw ◽  
Adsorption Characteristics ◽  
Layer Adsorption ◽  
Adsorption Data ◽  
Renewable Material ◽  
Increasing Temperature ◽  
And Diffusion ◽  
Positive Effect ◽  
Single Molecular Layer

Heavy metal pollution has adversely affected the ecological environment. As an eco-friendly and renewable material, biochar has a positive effect on environmental restoration. For study the feasibility of removing lead using corn straw biochar, the adsorption characteristics and mechanism were studied. This work prepared corn straw biochar at 300 °C, and its surface properties were characterized. The adsorption kinetics, isotherm, thermodynamics were determined. The result indicated the mechanism belonged ion exchange and complexation, and the experiment were controlled by comprehensive process, which included reaction rate and diffusion. The Langmuir model had better fitting results for the adsorption data, which indicated that adsorption was chemical adsorption and single molecular layer adsorption, and the maximum adsorption amount of corn straw biochar at 25 °C, 35 °C and 45 °C were 81.63 mg/g, 83.89 mg/g and 89.21 mg/g respectively. The thermodynamic analysis showed that increasing temperature was helpful to adsorption, and the adsorption was spontaneous. The results can be used for comprehensive utilization of straw and treatment of lead pollution.

scholarly journals Solidification and superlubricity with molecular alkane films

2019 ◽  
Vol 116 (51) ◽  
pp. 25418-25423 ◽  
Author(s):  
Alexander M. Smith ◽  
James E. Hallett ◽  
Susan Perkin
Keyword(s):  
Solid Phase ◽  
Molecular Layer ◽  
Friction Coefficients ◽  
Model Studies ◽  
Surface Alignment ◽  
Hydrocarbon Films ◽  
Nanoscale Films ◽  
Alkane Films ◽  
And Control ◽  
Single Molecular Layer

Hydrocarbon films confined between smooth mica surfaces have long provided an experimental playground for model studies of structure and dynamics of confined liquids. However, fundamental questions regarding the phase behavior and shear properties in this simple system remain unsolved. With ultrasensitive resolution in film thickness and shear stress, and control over the crystallographic alignment of the confining surfaces, we here investigate the shear forces transmitted across nanoscale films of dodecane down to a single molecular layer. We resolve the conditions under which liquid–solid phase transitions occur and explain friction coefficients spanning several orders of magnitude. We find that commensurate surface alignment and presence of water at the interfaces each lead to moderate or high friction, whereas friction coefficients down toμ≈0.001are observed for a single molecular layer of dodecane trapped between crystallographically misaligned dry surfaces. This ultralow friction is attributed to sliding at the incommensurate interface between one of the mica surfaces and the laterally ordered solid molecular film, reconciling previous interpretations.

Powder x-ray diffraction of turbostratically stacked layer systems

1996 ◽  
Vol 11 (7) ◽  
pp. 1733-1738 ◽  
Author(s):  
D. Yang ◽  
R. F. Frindt
Keyword(s):  
Special Form ◽  
Molecular Layer ◽  
X Ray Diffraction ◽  
Layer System ◽  
X Ray ◽  
Debye Formula ◽  
Diffraction Patterns ◽  
Single Molecular Layer ◽  
Deposition Conditions

A special form of the Debye formula for calculating the powder x-ray diffraction of a turbostratically stacked layer system is derived, and calculated diffraction patterns for turbostratically stacked graphite and MoS2 layers are presented. Single-molecular-layer MoS2, prepared by exfoliation of lithium-intercalated MoS2 in water or alcohols, has been deposited on various supports, and x-ray diffraction patterns show that the restacking of the MoS2 layers can be perfectly turbostratic. The restacked MoS2 may or may not have water or organic bilayers between them, depending on the deposition conditions.

The remarkable activity and stability of a dye-sensitized single molecular layer MoS2ensemble for photocatalytic hydrogen production

2015 ◽  
Vol 51 (70) ◽  
pp. 13496-13499 ◽  
Author(s):  
Tiantian Jia ◽  
Molly M. J. Li ◽  
Lin Ye ◽  
Sam Wiseman ◽  
Guoliang Liu ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Binding Affinity ◽  
Molecular Layer ◽  
Single Layer ◽  
Eosin Y ◽  
Photocatalytic Hydrogen Production ◽  
Dye Sensitized ◽  
Strong Binding ◽  
Single Molecular Layer ◽  
Dye Molecule

Single layer MoS2synthesized by exfoliation with Li is demonstrated to take up the dye molecule, Eosin Y, with strong binding affinityviasulfur vacancies.

The area of real contact and the shear strength of monomolecular layers of a boundary lubricant

1955 ◽  
Vol 227 (1171) ◽  
pp. 500-515 ◽  
Keyword(s):  
Shear Strength ◽  
Molecular Layer ◽  
Tangential Force ◽  
Surface Damage ◽  
Calcium Stearate ◽  
A Value ◽  
Boundary Lubricant ◽  
Tangential Forces ◽  
Monomolecular Layers ◽  
Single Molecular Layer

A method has been developed by which molecularly smooth surfaces may be placed together and the area of contact formed between them measured. Selected sheets of mica were cleaved to be free from cleavage steps on both sides of the sheets. These were bowed up and mounted as crossed cylinders in an apparatus in which normal and tangential loads could be applied. The area of contact formed between the surfaces has been examined using multiple-beam interference techniques. Examination of the hue and intensity of the central region of the interferograms enables a separation of the mica sheets to be detected even if this is of only a few ångströms. This means that the boundary of the region of contact may be determined with a greater precision than has hitherto been possible. Fringes of equal chromatic order provide a sensitive means for the detection of small particles of accidental contamination and have been used to show when the contact is intimate over the whole region. Normal and tangential forces have been applied to the mica specimens, both when in a clean condition and when covered with a monomolecular layer of calcium stearate. The area of contact was observed simultaneously. The area and the force required to shear it being known, the shear strength of the junctions has been calculated. The damage occurring during the process has been examined using reflexion electron microscopy. At certain values of the tangential force smooth sliding takes place on the lubricated surfaces and no surface damage can be detected. Further increase of the tangential force produces a rapid slip causing fragments to be torn out of the surface and some damage occurs. No smooth sliding was detected on unlubricated surfaces of mica and the damage produced during the slip was extensive. The force required to shear the junction formed between clean smooth mica surfaces is very high. A value of 10 Kg/mm 2 has been obtained. For the monomolecular layers of calcium stearate the value obtained is about forty times lower but is by no means negligible. This means that a considerable force is required to shear a film of boundary lubricant and accounts for the otherwise unexplained observation that when metals are lubricated with a single molecular layer of soap or fatty acid the frictional force is reduced by only a factor of 10 while the wear decreases by a factor of 10000 or more.

scholarly journals Dynamics of propylene glycol and its oligomers confined to a single molecular layer

2005 ◽  
Vol 122 (24) ◽  
pp. 244702 ◽  
Author(s):  
J. Swenson ◽  
D. Engberg ◽  
W. S. Howells ◽  
T. Seydel ◽  
F. Juranyi
Keyword(s):  
Propylene Glycol ◽  
Molecular Layer ◽  
Single Molecular Layer

High-resolution structural analysis of purple membrane

1983 ◽  
Vol 41 ◽  
pp. 418-421
Author(s):  
R. Henderson ◽  
J.M. Baldwin ◽  
D.A. Agard ◽  
D. Leifer
Keyword(s):  
Single Molecule ◽  
Molecular Layer ◽  
Purple Membrane ◽  
Three Dimensions ◽  
Electron Microscopic ◽  
Crystal Forms ◽  
Protein Molecules ◽  
Single Molecular Layer ◽  
Common Shape ◽  
Better Than

Two crystal forms of the purple membrane from Halobacterium halobium are being investigated. One is the native p3 form which occurs naturally, and the other is an orthorhombic p22121 form which is made artificially with detergent.Both forms diffract to better than 3 Å resolution. They have been studied by electron diffraction at high (3 Å) resolution, and at lower resolution (6.5-7 Å) by electron microscopy. Both crystal forms occur as membrane sheets, containing a single molecular layer of protein molecules with a lipid bilayer filling the space between the protein molecules, the whole having a thickness of about 45-50 Å. The electron microscopic and diffraction analyses have been carried out in three dimensions using specimens tilted at angles of up to 60° to the incident electron beam.The resulting Fourier maps of the two structures enable a common shape for a single molecule of bacteriorhodopsin to be determined, which is free of the ambiguity of molecular boundary normally found in crystal structure analyses at lower resolution than that required to trace the path of the polypeptide chain.

Sign in / Sign up

Export Citation Format

Share Document