Crystal Size
Recently Published Documents


TOTAL DOCUMENTS

1774
(FIVE YEARS 587)

H-INDEX

80
(FIVE YEARS 26)

Author(s):  
Liliana Yanet López-Velázquez ◽  
Sergio Salgado-García ◽  
Samuel Cordova-Sánchez ◽  
Cintya Valerio-Cardenas ◽  
Gloria Ivette Bolio-Lopez ◽  
...  

Objective: The aim of this study was to determine the cellulose content and characteristics of sugarcane straw from the cultivars MEX 69-290, MEX 68-P-23, CO-997, SP 70-1284 and CP 72-2086. Design/methodology/approach: A completely random experimental design with six replicates was conducted; the study factor was the sugarcane straw from the five evaluated cultivars. For cellulose extraction, the sodium hydroxide (soda) method was used on dried sugarcane straw of 2 mm. The crystallinity and crystal size were determined with x-ray diffraction (XRD); the fiber length had achieved a measurement with a DMRE optical microscope.   Results: Among the results, it can be noted that the cultivars MEX 69-290 and SP 70-1284, which presented less cellulose content (8.4 g and 8.5 g) and lower yields (42.1% and 42.6%), while the cultivar CO-997, presented higher cellulose content and yield which ranged from 9.8 g to 49.8%. The crystallinity of cellulose was higher in the sugarcane straw from the cultivars SP 70-1284 and MEX 68-P23. The crystal size of cellulose was 2.3 nm. The length of cellulose fibers was small (<945.7 µm). Study limitations/implications: The collection of samples in the field, as well as selected materials for digestion. Findings/conclusions: The sugarcane straw is a potential source of cellulose for the paper industry.  


Photonics ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 436
Author(s):  
Yuhe Wang ◽  
Yudong Lian ◽  
Shiwei Han ◽  
Yang Yu ◽  
Xuan Qi ◽  
...  

A scheme for controlling the frequency difference of output pulse pair with double frequency shift loops is proposed. The frequency shift system includes two loop elements of 20 and 200 MHz. The first one carries out a single selective positive frequency shift of 1–20 MHz, and the second one can satisfy a single fixed positive frequency shift of 200 MHz. The reverse cascade technology of two acousto-optic crystals is introduced to solve the limitation of the small frequency shift of crystal size. A multichannel synchronization signal completes the time domain control of each acousto-optic modulator. Finally, the frequency shift difference of the output pulse pair ranges of 0–2 GHz, and the frequency shift accuracy is 5 MHz.


2021 ◽  
Vol 83 (11) ◽  
Author(s):  
Aristle Monteiro ◽  
Raymond A. Duraiswami ◽  
Tushar Mittal ◽  
Shrishail Pujari ◽  
Upananda Low ◽  
...  

2021 ◽  
Vol 900 ◽  
pp. 172-179
Author(s):  
Mohammed Abdul Nebi Thejeel ◽  
Rihab Nassr Fadhil ◽  
Shatha H. Mahdie ◽  
Kareem Ali Jasim ◽  
Auday H. Shaban

In this manuscript, the effect of substituting strontium with barium on the structural properties of Tl0.8Ni0.2Sr2-xBrxCa2Cu3O9-δ compound with x= 0, 0.2, 0.4, have been studied. Samples were prepared using solid state reaction technique, suitable oxides alternatives of Pb2O3, CaO, BaO and CuO with 99.99% purity as raw materials and then mixed. They were prepared in the form of discs with a diameter of 1.5 cm and a thickness of (0.2-0.3) cm under pressures 7 tons / cm2, and the samples were sintered at a constant temperature of 860 ° C. The structural properties were studied using X-ray diffraction for all samples, and the results showed that the samples have tetragonal structure and the change of the parameters structure with the change of the barium concentration. Full Width Half Maximum (FWHM) was calculated by Orange Pro using X-RAY data. The crystal size was calculated using Scherrer and Willeamson-Heall methods, where the results showed that the crystal size, compliance and degree of crystallinity changed with the change of barium concentration, and the highest average for the crystal size was 70.0271nm at x=0, and crystallization at 61.46% at x=0.6, and the strain decreased to 0.0037 when barium concentration equals 0.4.


Author(s):  
Peter Strogen

Pyrite-bearing unbound fills, widely used in eastern Ireland have heaved, causing serious structural damage to thousands of buildings. This study compares calcareous mudstones that degenerated rapidly, causing severe structural damage, with argillaceous limestones that did not. Framboidal pyrite in the mudstones is widely dispersed – every aggregate particle contains abundant framboidal pyrite. Oxidation of this produced sulfuric acid that reacted with calcite producing supersaturated solutions of CaSO4 and CO2 gas. It is suggested that the latter exerted pressures approaching 5 MPa within rock particles, creating micro-fractures into which gypsum crystallised. Antitaxial growth of gypsum continued expansion, a process analogous to the formation of mineral veins in rocks. Heave of the fill took place since all the loadbearing particles expanded. The limestones have a lower pyrite content, which occurs mainly in the shaly seams and is concentrated in the fines; limestones suffered similar oxidation, but the coarser aggregate remains unaltered, and gypsum is mainly pore-filling; little expansive force was generated. It is concluded that the actual amount of pyrite present is a less important factor controlling expansion of unbound fills than its crystal size, and its distribution throughout the aggregate.


Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1584
Author(s):  
María E. Eugenio ◽  
Mercedes Ruiz-Montoya ◽  
Raquel Martín-Sampredro ◽  
David Ibarra ◽  
Manuel J. Díaz

Cellulose is the most abundant component of biomass and the one that requires the most activation energy (Ea) for pyrolysis. In this study, the dependence of Ea on the intrinsic cellulose characteristics, such as the degree of polymerization (DP), crystallinity, and crystal size, was studied in different cellulose samples, including samples from Eucalyptus globulus, Ulmus minor, Linun usitatissimum, Olea europaea, Robinia pseudoacacia, and Populus alba. Then, to describe the pyrolytic degradation of cellulose, the Ozawa–Flynn–Wall kinetic method was the most appropriate among the isoconversional models studied. An acceptable quadratic relationship of R2 > 0.9 between the Ea values of the different cellulose samples with their corresponding DP, crystallinity index, and crystal size values was found. Therefore, low crystallinity and low-to-medium crystal size values are desired to obtain lower Ea values for cellulose pyrolysis. On the other hand, DP did not present a clear effect on Ea in the studied DP range.


Sign in / Sign up

Export Citation Format

Share Document