Characteristics of ray patterns and caustic patterns in a nonhomogeneous parabolic layer

1977 ◽  
Vol 20 (11) ◽  
pp. 1148-1153 ◽  
Author(s):  
Yu. I. Orlov
Keyword(s):  
Ray Patterns ◽  
Parabolic Layer

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

scholarly journals Maghemite in Brazilian Iron Ores: Quantification of the Magnetite-Maghemite Isomorphic Series by Χ-ray Diffraction and the Rietveld Method, and Confirmation by Independent Methods

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 346
Author(s):  
Renata Hiraga ◽  
Otávio Gomes ◽  
Reiner Neumann
Keyword(s):  
Solid Solution ◽  
Rietveld Method ◽  
Isomorphic Substitution ◽  
Iron Ores ◽  
Reflected Light ◽  
Magnetite Crystal ◽  
Brazilian Soils ◽  
Isomorphic Series ◽  
Ore Characterization ◽  
Ray Patterns

Maghemite (γ-Fe2O3) is a mineral formed from magnetite oxidation at low temperatures, an intermediate metastable term of the magnetite to hematite oxidation and could be mixed with both. It has magnetic susceptibility similar to magnetite, crystal structure close to magnetite with which it forms a solid solution, while compositionally it equals hematite. Maghemite is thus easily misidentified as magnetite by Χ-ray diffraction and/or as hematite by spot chemical analysis in iron ore characterization routines. Nonstoichiometric magnetite could be quantified in samples of Brazilian soils and iron ores by the Rietveld method using a constrained refinement of the Χ-ray patterns. The results were confirmed by reflected light microscopy and Raman spectroscopy, thus qualitatively validating the method. Χ-ray diffraction with the refinement of the isomorphic substitution of Fe2+ by Fe3+ along the magnetite-maghemite solid solution could help to suitably characterize maghemite in iron ores, allowing for the evaluation of its ultimate influence on mineral processing, as its effect on surface and breakage properties.

HIV-TUBERCULOSIS: A STUDY OF CHEST X-RAY PATTERNS IN RELATION TO CD4 COUNT

2021 ◽  
pp. 10-12
Author(s):  
Abdhesh Kumar ◽  
Naveen Kumar ◽  
Kumar Sourav
Keyword(s):  
Pulmonary Tuberculosis ◽  
Tertiary Hospital ◽  
Hiv Positive ◽  
Who Guidelines ◽  
X Ray ◽  
Ciency Virus ◽  
Chest X Ray ◽  
Radiological Patterns ◽  
High Index Of Suspicion ◽  
Ray Patterns

Background: Fight against human immunodeciency virus (HIV) is incomplete without addressing problems associated with difcult diagnosis of tuberculosis in HIV-Tuberculosis coinfected patients. Chest X-ray is a primary tool to evaluate tuberculosis in HIV. Aim: To assess and compare various radiological patterns of pulmonary tuberculosis in HIV patients and compare these patterns in relation to CD4 counts. Materials and Methods: Prospective cohort study was conducted in a tertiary hospital in J.L.N.M.C.H Bhagalpur from april 2019 to january 2021 with 200 HIV positive patients. WHO guidelines were used for diagnosis of HIV and tuberculosis. Results: 27% of the patients had sputum positive pulmonary tuberculosis, with higher incidence (33%) among CD4 less than 200 as compared to CD4 more than 200 (14%). Inltration (39%) followed by consolidation (30%), cavity (11%), and lymphadenopathy (9%) seen with CD4 less than 200. Inltration (37.5%) followed by cavity (25%) and miliary (25%) with CD4 above 200. Bilateral (68.5%) and mid and lower zones or all zone involvement more commonly seen. Conclusion: In patients with CD4 lower than 200 noncavitory inltration and consolidation predominated. Involvement of lungs was atypical; diffuse or mid and lower zone involvement was higher than classical upper lobe involvement. A high index of suspicion is necessary for the accurate and timely diagnosis of tuberculosis in HIVpositive patients.

scholarly journals X-RAY DIFFRACTION STUDIES ON AMYLOID FILAMENTS

1968 ◽  
Vol 16 (11) ◽  
pp. 673-677 ◽  
Author(s):  
E. D. EANES ◽  
G. G. GLENNER
Keyword(s):  
Polypeptide Chain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Filament Axis ◽  
Adjacent Chain ◽  
Diffuse Halo ◽  
Sheet Structure ◽  
Regular Manner ◽  
Ray Patterns ◽  
Pleated Sheet

The filamentous protein component of amyloid-laden tissue was studied by x-ray diffraction procedures. The principal features of the x-ray pattern from nonoriented amyloid material consist of a sharp, intense ring at 4.75 Å overlaying a diffuse halo at 4.3 Å, and a broad and less intense ring at 9.8 Å. When oriented, the material gives a "cross-β" x-ray pattern. The x-ray findings are interpreted in terms of a "pleated sheet" structure formed by the amyloid polypeptide chain folding in a regular manner on itself such that adjacent chain segments are laterally arranged in an antiparallel manner. The x-ray patterns from oriented amyloid suggest further that the axes of the chain segments run transverse to the filament axis.

Absorption Edges in the X-Ray Patterns of Native and Mercerized Cellulose

1936 ◽  
Vol 58 (9) ◽  
pp. 1635-1638 ◽  
Author(s):  
Wayne A. Sisson ◽  
George L. Clark ◽  
Edward A. Parker
Keyword(s):  
X Ray ◽  
Ray Patterns ◽  
Absorption Edges

scholarly journals Production and Physicochemical Properties of Starch Isolated from Djulis (Chenopodium formosanum)

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 551 ◽  
Author(s):  
Wen-Chien Lu ◽  
Yung-Jia Chan ◽  
Fang-Yu Tseng ◽  
Po-Yuan Chiang ◽  
Po-Hsien Li
Keyword(s):  
Physicochemical Properties ◽  
Amylose Content ◽  
Starch Content ◽  
Isolation Procedure ◽  
Point Of View ◽  
Degree Of Crystallinity ◽  
Morphological Observation ◽  
Scanning Calorimetry ◽  
Transition Range ◽  
Ray Patterns

Djulis (Chenopodium formosanum Koidz.) is an annual fast-growing underutilized pseudo cereal with a high percentage of starch content. In this study, djulis starch was extracted from the flour of dried grains by three different isolation procedures: (1) hydrochloric acid (HCl) isolation procedure (HP); (2) deionized water isolation procedure (WP); and (3) sodium hydroxide (NaOH) isolation procedure (NP), followed by investigation of the physicochemical properties of the isolated djulis starch. The amylose content of HP, WP, and NP was 22.14%, 24.15%, and 22.43%, respectively. For scanning electron microscopy (SEM) morphological observation, djulis starch presented a polygonal shape with granule sizes of 0.56–1.96, 0.74–3.02, and 0.62–2.48 μm, respectively. Djulis starch showed the classification of typical A-type x-ray patterns, and the relative degree of crystallinity for HP, WP, and NP was 33.15%, 36.17%, and 37.42%, respectively. Differential scanning calorimetry (DSC) analysis was used to determine the transition temperatures, transition range, and enthalpies of the gelatinization of starches. HP and WP isolated starch exhibited the highest ΔH 9.24 and 8.51 J/g, respectively, whereas NP starch showed the lowest ΔH of 6.95 J/g. The pasting temperatures of HP, WP, and NP isolated starch, which were analyzed by using a Rapid Visco Analyzer (RVA), were 71.70 °C, 72.80 °C, and 69.53 °C, respectively. The dependence of swelling power for the three isolated starches on temperature was tested at 10 °C with intervals between 60 °C and 90 °C. In short, the NP isolation procedure with a stable reaction is compelling from a technological point of view.

scholarly journals Fin ray patterns at the fin-to-limb transition

2019 ◽  
Vol 117 (3) ◽  
pp. 1612-1620 ◽  
Author(s):  
Thomas A. Stewart ◽  
Justin B. Lemberg ◽  
Natalia K. Taft ◽  
Ihna Yoo ◽  
Edward B. Daeschler ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Structure And Function ◽  
Crown Group ◽  
Cross Sectional ◽  
Pectoral Fins ◽  
The Third ◽  
Fin Ray ◽  
Fin Rays ◽  
And Function ◽  
Ray Patterns

The fin-to-limb transition was marked by the origin of digits and the loss of dermal fin rays. Paleontological research into this transformation has focused on the evolution of the endoskeleton, with little attention paid to fin ray structure and function. To address this knowledge gap, we study the dermal rays of the pectoral fins of 3 key tetrapodomorph taxa—Sauripterus taylori (Rhizodontida), Eusthenopteron foordi (Tristichopteridae), and Tiktaalik roseae (Elpistostegalia)—using computed tomography. These data show several trends in the lineage leading to digited forms, including the consolidation of fin rays (e.g., reduced segmentation and branching), reduction of the fin web, and unexpectedly, the evolution of asymmetry between dorsal and ventral hemitrichia. In Eusthenopteron, dorsal rays cover the preaxial endoskeleton slightly more than ventral rays. In Tiktaalik, dorsal rays fully cover the third and fourth mesomeres, while ventral rays are restricted distal to these elements, suggesting the presence of ventralized musculature at the fin tip analogous to a fleshy “palm.” Asymmetry is also observed in cross-sectional areas of dorsal and ventral rays. Eusthenopteron dorsal rays are slightly larger than ventral rays; by contrast, Tiktaalik dorsal rays can be several times larger than ventral rays, and degree of asymmetry appears to be greater at larger sizes. Analysis of extant osteichthyans suggests that cross-sectional asymmetry in the dermal rays of paired fins is plesiomorphic to crown group osteichthyans. The evolution of dermal rays in crownward stem tetrapods reflects adaptation for a fin-supported elevated posture and resistance to substrate-based loading prior to the origin of digits.

Mixed-layer mica-chlorite in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain)

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 307-324 ◽  
Author(s):  
M. D. Ruiz Cruz
Keyword(s):  
Electron Microscopy ◽  
Mixed Layer ◽  
Analytical Electron Microscopy ◽  
Low Grade ◽  
X Ray ◽  
Betic Cordilleras ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Microscopy Data ◽  
Ray Patterns

AbstractMixed-layered phyllosilicates with composition intermediate between mica and chlorite were identified in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain), and studied by X-ray diffraction, and transmission and analytical electron microscopy. They occur both as small grains in the rock matrix, and associated with muscovitechlorite stacks. Transmission electron microscope observations revealed a transition from chlorite to ordered 1:1 interstratifications through complex 1:2 and 1:3 interstratifications. Analytical electron microscopy data indicate a composition slightly different from the sum of discrete trioctahedral chlorite and dioctahedral mica. The types of layer transitions suggest that mixed-layer formation included two main processes: (1) the replacement of a brucite sheet by a cation sheet in the chlorite structure; and (2) the precipitation of mica-like layers between the chlorite layers. The strongest diffraction lines in oriented X-ray patterns are: 12.60 Å (002), 7.98 Å (003), 4.82 Å (005) and 3.48 Å (007).

STRUCTURAL AND OPTICAL PROPERTIES OF UNDOPED AND SILVER, LITHIUM AND COBALT-DOPED ZnO THIN FILMS

2019 ◽  
Vol 27 (04) ◽  
pp. 1950138
Author(s):  
FATMA MEYDANERİ TEZEL ◽  
İ. AFŞIN KARİPER
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Optical Transmittance ◽  
Refraction Index ◽  
Zno Thin Films ◽  
High Temperature Furnace ◽  
Doped Zno ◽  
Ray Patterns ◽  
Temperature Furnace

Undoped and silver, lithium and cobalt-doped ZnO thin films have been successfully deposited on glass by chemical bath deposition (CBD). The reaction temperature was 50∘C and the films were annealed at 400∘C for 4[Formula: see text]h in a high temperature furnace. UV/VIS spectrum was used to determine optical transmittance, optical band gap ([Formula: see text] and absorbance values of Ag:ZnO, Co:ZnO, Li:ZnO and undoped ZnO thin films. Optical band gap ([Formula: see text] and absorbance values of undoped ZnO, Ag:ZnO, Co:ZnO and Li:ZnO thin films were found as 0.0158, 0.0064, 0.2638, 0.0956 and 3.24, 3.13, 3.27, 2.96 eV, respectively. Extinction coefficients and refraction indexes of the films were found to be 0.0096, 0.0038, 0.0068, 0.019 (extinction coefficient) and 1.26, 1.14, 1.66, 2.33 (refraction index), respectively. X-ray patterns of undoped ZnO, Ag:ZnO, Co:ZnO and Li:ZnO thin films were confirmed as amorphous.

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