Study of Tribochemical Processes on Hard Disks Using Photoemission Electron Microscopy

1999 ◽  
Vol 121 (4) ◽  
pp. 961-967 ◽  
Author(s):  
Simone Anders ◽  
Thomas Stammler ◽  
Walton Fong ◽  
Chao-Yuan Chen ◽  
David B. Bogy ◽  
...  
Keyword(s):  
Hard Disks ◽  
Chemical Modifications ◽  
Hard Carbon ◽  
Carbon Overcoat ◽  
Chemical Changes ◽  
X Ray ◽  
Tribochemical Processes ◽  
Carbon Coated ◽  
Photoemission Electron ◽  
Wear Tests

The interface between hard disk and slider involves mechanical and tribochemical processes between the hard carbon overcoat of the disk, the lubricant, and the carbon coated or uncoated slider surface. These processes have been studied by two related X-ray techniques—Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy and Photoemission Electron Microscopy (PEEM) using X-rays. NEXAFS allows studying the elemented composition and chemical bonding in a material, whereas PEEM combines this ability with imaging of the sample. Lubricated and unlubricated disks were worn under various conditions using carbon coated and uncoated sliders. The wear tracks on the hard disks were investigated using PEEM to find chemical and elemental changes caused by the wear. Local NEXAFS spectra taken in wear tracks using the PEEM microscope show no chemical changes on unlubricated disks, just a reduction of the hard carbon overcoat thickness. On lubricated disks remarkable chemical modifications of the lubricants caused by the wear are observed if the disks failed the wear tests. The chemical changes are manifested in a formation of various new carbon-oxygen (mostly carboxylic) bonds in the wear tracks and in a strong reduction of the amount of fluorine and carbon. The chemical modifications were only found inside the wear tracks and are clearly caused by the wear. It was found that lubricant degradation is not solely a mechanical process of molecule scission but accompanied by oxidation reactions. The chemical changes were strongly correlated to the tribological behavior of the disks: the worse the disks performed in the wear tests, the stronger were the chemical modifications.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

Pyrotechnic Residues in Gunshot Residue Analysis

1985 ◽  
Vol 43 ◽  
pp. 128-129
Author(s):  
H. M. Sagara ◽  
S. A. Schliebe ◽  
M. C. Kong
Keyword(s):  
Law Enforcement ◽  
Residue Analysis ◽  
Gunshot Residue ◽  
Particle Analysis ◽  
Dry Skin ◽  
X Ray ◽  
Skin Cells ◽  
Smokeless Powder ◽  
Carbon Coated ◽  
Detailed List

Particle analysis by scanning electron microscopy with energy-dispersive x- ray analysis is one of the current methods used in crime laboratories to aid law enforcement in identifying individuals who have recently fired or handled a firearm. During the discharge of a firearm, the high pressure caused by the detonation of the cartridge materials forces a portion of the generated gases through leaks in the firing mechanism of the weapon. These gases contain residues of smokeless powder, primer mixture, and contributions from the projectile itself. The condensation of these hot gases form discrete, micrometer-sized particles, which can be collected, along with dry skin cells, salts, and other hand debris, from the hands of a shooter by a simple adhesive lift technique. The examination of the carbon-coated adhesive lifts consist of time consuming systematic searches for high contrast particles of spherical morphology with the characteristic elemental composition of antimony, barium and lead. A detailed list of the elemental compositions which match the criteria for gunshot residue are discussed in the Aerospace report.

scholarly journals Carbon-coated magnetic particles increase tissue temperatures after laser irradiation

2015 ◽  
Vol 08 (05) ◽  
pp. 1550018 ◽  
Author(s):  
Shupeng Liu ◽  
Na Chen ◽  
Fufei Pang ◽  
Zhengyi Chen ◽  
Tingyun Wang
Keyword(s):  
Laser Irradiation ◽  
Magnetic Particles ◽  
Laser Energy ◽  
Thermal Therapy ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fbg Sensor ◽  
Transmission Electron ◽  
Carbon Coated

Purpose: This work focused on the investigation the hyperthermia performance of the carbon-coated magnetic particles (CCMPs) in laser-induced hyperthermia. Materials and methods: We prepared CCMPs using the organic carbonization method, and then characterized them with transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) spectrophotometry, vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). In order to evaluate their performance in hyperthermia, the CCMPs were tested in laser-induced thermal therapy (LITT) experiments, in which we employed a fully distributed fiber Bragg grating (FBG) sensor to profile the tissue's dynamic temperature change under laser irradiation in real time. Results: The sizes of prepared CCMPs were about several micrometers, and the LITT results show that the tissue injected with the CCMPs absorbed more laser energy, and its temperature increased faster than the contrast tissue without CCMPs. Conclusions: The CCMPs may be of great help in hyperthermia applications.

Element-specific structural analysis of Si/B4C using resonant X-ray reflectivity

2015 ◽  
Vol 48 (3) ◽  
pp. 786-796 ◽  
Author(s):  
Maheswar Nayak ◽  
P. C. Pradhan ◽  
G. S. Lodha
Keyword(s):  
Thin Film ◽  
Spatial Distribution ◽  
Structural Analysis ◽  
Chemical Changes ◽  
X Ray ◽  
Buried Interfaces ◽  
Smooth Interface ◽  
Specific Composition ◽  
Applied Fields ◽  
Spatial Modulations

Element-specific structural analysis at the buried interface of a low electron density contrast system is important in many applied fields. The analysis of nanoscaled Si/B4C buried interfaces is demonstrated using resonant X-ray reflectivity. This technique combines information about spatial modulations of charges provided by scattering, which is further enhanced near the resonance, with the sensitivity to electronic structure provided by spectroscopy. Si/B4C thin-film structures are studied by varying the position of B4C in Si layers. Measured values of near-edge optical properties are correlated with the resonant reflectivity profile to quantify the element-specific composition. It is observed that, although Si/B4C forms a smooth interface, there are chemical changes in the sputtered B4C layer. Nondestructive quantification of the chemical changes and the spatial distribution of the constituents is reported.

Sorption and thermodynamic properties of juvenile Pinus sylvestris L. wood after 103 years of submersion

Holzforschung ◽  
2008 ◽  
Vol 62 (6) ◽  
Author(s):  
Luis García Esteban ◽  
Paloma de Palacios ◽  
Francisco García Fernández ◽  
Antonio Guindeo ◽  
Marta Conde ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Pinus Sylvestris ◽  
Integration Method ◽  
Juvenile Wood ◽  
Crystallinity Index ◽  
Isosteric Heat ◽  
Chemical Modifications ◽  
Clapeyron Equation ◽  
X Ray ◽  
Hemicellulose Degradation

Abstract The hygroscopicity and thermodynamic properties of juvenile Pinus sylvestris L. wood taken from the submerged piles of a bridge built in 1903 over the Jiloca River, in Spain, were compared with the corresponding values of juvenile wood of the same species from recently cut trees. The 35°C and 50°C isotherms were plotted and subsequently fitted using the Guggenheim-Anderson-Boer-Dent method, and the isosteric heat of sorption was obtained through the integration method of the Clausius-Clapeyron equation. The isotherms were compared by means of the hysteresis coefficients. Infrared spectra were recorded to study the chemical modifications, and the crystal structure of the cellulose was studied by X-ray diffractograms. The submersion in water resulted in hemicellulose degradation and a decrease in the crystallinity index and the crystallite length, accompanied by a corresponding increase in the proportion of amorphous zones. Owing to this, the equilibrium moisture contents of the water logged wood are higher than in the recent wood, both in adsorption and in desorption. In terms of the thermodynamic properties, the bond energy is higher in the recent wood than in the water logged wood.

HIGH POWER PERFORMANCE OF MULTICOMPONENT OLIVINE CATHODE MATERIAL FOR LITHIUM-ION BATTERIES

2011 ◽  
Vol 04 (03) ◽  
pp. 299-303 ◽  
Author(s):  
ZHUO TAN ◽  
PING GAO ◽  
FUQUAN CHENG ◽  
HONGJUN LUO ◽  
JITAO CHEN ◽  
...  
Keyword(s):  
Transition Metal ◽  
Cathode Material ◽  
High Capacity ◽  
Rate Capability ◽  
Lithium Ion ◽  
Coprecipitation Method ◽  
Homogeneous Distribution ◽  
Power Performance ◽  
X Ray ◽  
Carbon Coated

A multicomponent olivine cathode material, LiMn0.4Fe0.6PO4 , was synthesized via a novel coprecipitation method of the mixed transition metal oxalate. X-ray diffraction patterns indicate that carbon-coated LiMn0.4Fe0.6PO4 has been prepared successfully and that LiMn0.4Fe0.6PO4/C is crystallized in an orthorhombic structure without noticeable impurity. Homogeneous distribution of Mn and Fe in LiMn0.4Fe0.6PO4/C can be observed from the scanning electron microscopy (SEM) and the corresponding energy dispersive X-ray spectrometry (EDS) analysis. Hence, the electrochemical activity of each transition metal in the olivine synthesized via coprecipitation method was enhanced remarkably, as indicated by the galvanostatic charge/discharge measurement. The synthesized LiMn0.4Fe0.6PO4/C exhibits a high capacity of 158.6 ± 3 mAhg-1 at 0.1 C, delivering an excellent rate capability of 122.6 ± 3 mAhg-1 at 10 C and 114.9 ± 3 mAhg-1 at 20 C.

scholarly journals Carbon-Coated SiO2 Composites as Promising Anode Material for Li-Ion Batteries

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4531
Author(s):  
Mihaela-Ramona Buga ◽  
Adnana Alina Spinu-Zaulet ◽  
Cosmin Giorgian Ungureanu ◽  
Raul-Augustin Mitran ◽  
Eugeniu Vasile ◽  
...  
Keyword(s):  
Anode Material ◽  
Photoelectron Spectroscopy ◽  
Coulombic Efficiency ◽  
Cycling Stability ◽  
Li Ion Batteries ◽  
Transfer Resistance ◽  
Promising Alternative ◽  
X Ray ◽  
Carbon Coated ◽  
Li Ion

Porous silica-based materials are a promising alternative to graphite anodes for Li-ion batteries due to their high theoretical capacity, low discharge potential similar to pure silicon, superior cycling stability compared to silicon, abundance, and environmental friendliness. However, several challenges prevent the practical application of silica anodes, such as low coulombic efficiency and irreversible capacity losses during cycling. The main strategy to tackle the challenges of silica as an anode material has been developed to prepare carbon-coated SiO2 composites by carbonization in argon atmosphere. A facile and eco-friendly method of preparing carbon-coated SiO2 composites using sucrose is reported herein. The carbon-coated SiO2 composites were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, cyclic voltammetry, and charge–discharge cycling. A C/SiO2-0.085 M calendered electrode displays the best cycling stability, capacity of 714.3 mAh·g−1, and coulombic efficiency as well as the lowest charge transfer resistance over 200 cycles without electrode degradation. The electrochemical performance improvement could be attributed to the positive effect of the carbon thin layer that can effectively diminish interfacial impedance.

Xps Analysis of the Sapphire Surface as a Function of High Temperature Vacuum Annealing

1989 ◽  
Vol 159 ◽  
Author(s):  
E.D. Richmond
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Xps Analysis ◽  
Chemical Changes ◽  
Cleaning Procedure ◽  
Sapphire Surface ◽  
X Ray ◽  
First Time

ABSTRACTFor the first time the (1102) surface of sapphire has been investigated by X-ray photoelectron spectroscopy to ascertain chemical changes resulting from annealing in vacuum at 1300° C and 1450° C. As received substrates had a substantial surface C contaminant. For substrates that were chemically cleaned before inserting them into the MBE system no trace of carbon is detected. A residual flourine contaminant results from the cleaning procedure and is desorbed by the vacuum annealing. Spectra of annealed substrates are compared to the unannealed chemically cleaned substrates. The annealed substrates exhibit 0.4 to 0.5 eV shift to higher binding energy of the Al peak and a 0.3 eV shift to higher binding energy of the O peak. In addition, a 2% depletion of oxygen from the surface occurs.

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