scholarly journals SYNTHESIS AND STUDY OF THE PROPERTIES OF XEROGELS DERIVED FROM SULFATED PINE ETHANOL LIGNIN

2021 ◽  
pp. 45-54
Author(s):  
Nadezhda Mikhaylovna Mikova ◽  
Vladimir Aleksandrovich Levdansky ◽  
Yelena Valentinovna Mazurova ◽  
Boris Nikolayevich Kuznecov
Keyword(s):  
Electron Microscopy ◽  
Furfuryl Alcohol ◽  
Pore Diameter ◽  
Polymer Chains ◽  
Gel Structure ◽  
Average Pore ◽  
Bet Method ◽  
First Time ◽  
Sulfur Containing ◽  
Scanning Electron

Organic xerogels based on lignin and tannins isolated from pine bark and wood were first obtained by condensation with formaldehyde and furfuryl alcohol in the presence of hydrochloric acid. The use of pine sulfated ethanol lignin made it possible for the first time to obtain sulfur-containing (up to 1.3% wt.) lignin-(tannin)-formaldehyde and lignin-(tannin)-furfuryl xerogels. The density of the obtained gels increases with the addition of tannins to lignin and varies in the range 0.13–0.39 g/cm3. Xerogels synthesized by condensation with furfuryl alcohol are stronger than those obtained using formaldehyde. The presence of sulfur in xerogels was confirmed by elemental and chemical analysis and IR spectroscopy. It was shown by scanning electron microscopy, that lignin-formaldehyde xerogels are formed from large polymer chains, consisting of interconnected aggregates of micron-sized particles and have large pores. The addition of tannins to the polycondensation system is accompanied by the formation of a more compact spatially crosslinked gel structure. BET method showed that all xerogels have low porosity, and lignin-furfuryl samples have a larger average pore diameter (7.2–14.5 nm) compared to lignin-formaldehyde samples (3.03–6.80 nm).

Preparation and Characterization TiO2 Aerogel Fibers

2013 ◽  
Vol 743-744 ◽  
pp. 434-437
Author(s):  
Miao Lv ◽  
Guo Tong Qin ◽  
Wei Wei
Keyword(s):  
Electron Microscopy ◽  
Pore Diameter ◽  
Supercritical Drying ◽  
Mass Ratio ◽  
Composite Fibers ◽  
X Ray Diffraction ◽  
Average Pore ◽  
X Ray ◽  
Adsorption Desorption ◽  
Scanning Electron

TiO2aerogel fibers have been fabricated by electron span combined supercritical drying technique. Polyvinylpyrrolidone (PVP)/TiO2composite fibers are prepared by electrospinning PVP and TiO2precursor Ti (OC4H9)4. TiO2aerogel fibers are obtained by supercritical drying PVP/TiO2composite fibers using ethanol as media. Structural of the aerogel fibers was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2adsorption at 77 K. The effect of mass ratio of PVP/TiO2was investigated. SEM shows that pore structure of nanofibers was well developed, with the diameter of nanofibers about 2 μm. N2adsorption/desorption data show that the highest surface area of aerogel fibers reached 241.6 m2/g with the average pore diameter about 10 nm. The aerogel fibers were anatase type TiO2.

scholarly journals INFLUENCE OF ACTIVE ACIDITY OF THE MEDIUM ON THE STABILITY OF MNO NANOPARTICLES

2020 ◽  
pp. 33-41
Author(s):  
Андрей Владимирович Блинов ◽  
Давид Гурамиевич Маглакелидзе ◽  
Александр Александрович Кравцов ◽  
Анастасия Александровна Блинова ◽  
Алексей Алексеевич Гвозденко ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Amino Acids ◽  
Scanning Electron Microscopy ◽  
Manganese Dioxide ◽  
Mass Ratios ◽  
Manganese Dioxide Nanoparticles ◽  
The Stability ◽  
First Time ◽  
Sulfur Containing ◽  
Scanning Electron

В работе впервые представлены результаты исследования микроструктуры наночастиц диоксида марганца, стабилизированных серосодержащими аминокислотами. По результатам сканирующей электронной микроскопии обнаружено наличие в образцах наночастиц диаметром 15 - 30 нм. С помощью спектрофотомерии установлены оптимальные массовые соотношения прекурсоров для получения стабильных золей наночастиц диоксида марганца, которые составляют KMnO: метионин - 1:1 и KMnO: цистеин - 3:1. Исследование влияния активной кислотности среды на стабильность наночастиц диоксида марганца показало, что образцы MnO, полученные с использованием метионина, стабильны при 4 ≤ pH ≤ 11, а с использованием цистеина стабильны при 5 ≤ pH ≤ 8. In this work, for the first time the results of studying the microstructure of manganese dioxide nanoparticles stabilized with sulfur-containing amino acids are presented. According to the results of scanning electron microscopy, nanoparticles with a diameter of 15 - 30 nm were presented in the samples. The optimal mass ratios of precursors were established by means of spectrophotometry, to obtain stable sols of manganese dioxide nanoparticles. The optimal mass ratios were: KMnO : methionine - 1:1 and KMnO : cysteine - 3:1. Investigation of the effect of the medium active acidity on the stability of manganese dioxide nanoparticles showed that MnO samples obtained with methionine are stable at 4 ≤ pH ≤ 11, and with cysteine - at 5 ≤ pH ≤ 8 .

Green Approach for the Reduction of Graphene Oxide by Thai Shallot

2016 ◽  
Vol 675-676 ◽  
pp. 696-699 ◽  
Author(s):  
Voranuch Thongpool ◽  
Akapong Phunpheok ◽  
Veeradate Piriyawong ◽  
Supanee Limsuwan
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Visible Spectroscopy ◽  
Green Approach ◽  
Reduced Graphene ◽  
Uv Visible ◽  
First Time ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds ◽  
Scanning Electron

In this paper, we used shallots in the reduction of graphene oxide for the first time. Flavone, sulfur-containing compounds, and polyphenolic derivatives in the bulb of shallot acted as good reducing agent for the reduction of GO. The GO and reduced graphene oxide (RGO) were characterized by scanning electron microscopy (SEM), ultraviolet (UV)-visible spectroscopy, thermogravimetric analysis (TGA) and Raman spectroscopy. GO and RGO were the transparent sheets with the sheet edges tend to scroll and fold slightly. RGO showed a maximum absorption peak at 267 nm and had better thermal stability than graphene oxide. Raman spectra indicated removal of oxygen at the surface of GO and formation of the defect in the graphene sheet.

Study of the fouling of inorganic membranes by acidified milks using scanning electron microscopy and electrophoresis. I. Membrane with pore diameter 0·2 μm

1991 ◽  
Vol 58 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Hamadi Attia ◽  
Michel Bennasar ◽  
Blas Tarodo De La Fuente
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pore Diameter ◽  
High Porosity ◽  
Inorganic Membranes ◽  
Protein Aggregate ◽  
Average Pore ◽  
Protein Film ◽  
Static Conditions ◽  
Scanning Electron

SummaryThe fouling of an inorganic microfiltration membrane with an average pore diameter of 0·2 μm obtained in static conditions with milk, acidified milk and acid coagulum was examined using scanning electron microscopy. The structure and porosity of external fouling related to the pH of the milk accounts for the performance and efficiency obtained in microfiltration. Electrophoretic analysis of permeate, characterized by lack of casein, shows that the deposit plays a fundamental role in mass transfer through filter layers. Variations in the physicochemical properties of casein as a function of pH at 50 °C were used to account for the development of the structure of fouling, which comprised three main states: (i) dense deposit of juxtaposed micelles, (ii) loose network formed by chains made up of bonded protein aggregate, (iii) irregular protein aggregate leading to high-porosity deposits. The presence of a protein film strongly adsorbed on the membrane layer of alumina particles is demonstrated.

Study of the fouling of inorganic membranes by acidified milks using scanning electron microscopy and electrophoresis. II. Membrane with pore diameter 0·8 μm

1991 ◽  
Vol 58 (1) ◽  
pp. 51-65 ◽  
Author(s):  
Hamadi Attia ◽  
Michel Bennasar ◽  
Blas Tarodo De la Fuente
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pore Diameter ◽  
Retention Rate ◽  
Operating Conditions ◽  
Low Flow ◽  
Inorganic Membranes ◽  
Average Pore ◽  
Static Conditions ◽  
Scanning Electron

SummaryThe functioning of an inorganic microfiltration membrane (Membralox-SCT) with an average pore diameter of 0·8 μm, used for processing milk, acidified milk and lactic coagulum, was studied using dynamic and static conditions. Milk processing (pH 6·62) gave acceptable rates of protein retention but at low flow rates. Study of the effect of operating parameters during microfiltration of coagulum led to determination of optimal operating conditions leading to satisfactory performance and adequate retention rate. The results are explained using a model of the formation and development of internal and external fouling of a mineral membrane. Observations using scanning electron microscopy related to the pH of milk were used to verify the model by showing that internal fouling occurred only when the pH was higher than 5·50. This internal fouling was closely linked with the physicochemical state of milk proteins. Indeed, the fouling particles visualized at the alumina grains of the membrane support changed progressively from individual micelles (pH 6·62) to a chain or clustered structure (pH 5·60). Electrophoretic study confirmed this observation and showed that casein was present in milk permeates (pH 6·62) but not in coagulum permeates (pH 4·40).

scholarly journals Influence of Chitin Source and Polymorphism on Powder Compression and Compaction: Application in Drug Delivery

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5269
Author(s):  
Linda Al-Hmoud ◽  
Deeb Abu Fara ◽  
Iyad Rashid ◽  
Babur Z. Chowdhry ◽  
Adnan A. Badwan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pore Diameter ◽  
Polymorphic Form ◽  
Polymer Chains ◽  
Crushing Strength ◽  
Polymorphic Forms ◽  
Fast Dissolution ◽  
Compaction Properties ◽  
Scanning Electron

The objective of the research reported herein is to compare the compaction properties of three different chitin extracts from the organisms most used in the seafood industry; namely crabs, shrimps and squids. The foregoing is examined in relation to their polymorphic forms as well as compression and compaction behavior. Chitin extracted from crabs and shrimps exhibits the α-polymorphic form whilst chitin extracted from squid pins displays a β-polymorphic form. These polymorphs were characterized using FTIR, X-ray powder diffraction and scanning electron microscopy. Pore diameter and volume differ between the two polymorphic powder forms. The β form is smaller in pore diameter and volume. Scanning electron microscopy of the two polymorphic forms shows clear variation in the arrangement of chitin layers such that the α form appears more condensed due to the anti-parallel arrangement of the polymer chains. True, bulk and tapped densities of these polymorphs and their mixtures indicated poor flowability. Nevertheless, compression and compaction properties obtained by applying Heckle and Kawakita analyses indicated that both polymorphs are able to be compacted with differences in the extent of compaction. Chitin compacts, regardless of their origin, showed a very high crushing strength with very fast dissolution which makes them suitable for use as fast mouth dissolving tablets. Moreover, when different chitin powders are granulated with two model drugs, i.e., metronidazole and spiramycin they yielded high crushing strength and their dissolution profiles were in accordance with compendial requirements. It is concluded that the source of chitin extraction is as important as the polymorphic form when compression and compaction of chitin powders is carried out.

SCANNING ELECTRON MICROSCOPE: POSSIBILITIES FOR STUDYING KIDNEY DISEASES

2020 ◽  
pp. 176-182
Author(s):  
Mamaeva S.N. ◽  
Vinokurov R.R. ◽  
Munkhalova Ya.A. ◽  
Dyakonova D.P. ◽  
Platonova V.A. ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Filtration Rate ◽  
Kidney Diseases ◽  
First Time ◽  
Scanning Electron

Currently, due to the intensive development of high-tech science-intensive medical and research devices, more and more attention is paid to the development of diagnostics of rare and difficult to diagnose diseases. It is known that among numerous nephropathies, hematuria may be the only symptom of kidney and urinary tract diseases, which complicates their diagnosis and treatment. In order to develop new approaches for the diagnosis of nephropathies, the authors have been studying the morphology of red blood cells in the blood and urine of children and adults using a scanning electron microscope for several years. The paper presents the results of studies of children with various kidney diseases, including IgA-nephropathy, and chronic glomerulonephritis. Scanning electron microscopy was used for the first time to detect nanoparticles on the surface of red blood cells, the size of which is comparable to the size of viruses, which became the basis for one of the authors ' assumptions, namely, the possible transport of certain types of viruses by red blood cells. Thus, some kidney diseases could be considered virus-associated. This paper presents for the first time the results of determining the glomerular filtration rate of both kidneys separately in the study of separate kidney function and of the study of urine smears obtained during catheterization of the ureters in patients with hydronephrosis of one of the kidneys by scanning electron microscopy. As in previous studies, nanoparticles were found on the surface of red blood cells, which leads to the conclusion about the possible viral nature of the disease of the considered patient. In addition, smear images obtained using a microscope showed a significant difference in the elements of the right and left kidneys urine, which did not contradict the data on the study of glomerular filtration rate. According to the authors, the capabilities of the scanning electron microscope can be applied in fundamental research of kidney diseases at the cellular and molecular levels, forming new ideas about their origin, as well as on the basis of which new methods of non-invasive diagnostics can be built.

scholarly journals Labellum and gynostemium micromorphology in Polystachya (Orchidaceae)

2020 ◽  
Vol 307 (1) ◽  
Author(s):  
Mytnik Joanna ◽  
Davies L. Kevin ◽  
Narajczyk Magdalena ◽  
Łuszczek Dorota ◽  
Kubiak Joanna ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Sub Saharan Africa ◽  
Capitate Trichomes ◽  
Sub Saharan ◽  
First Time ◽  
Scanning Electron

AbstractPolystachya is a large, pantropical orchid genus of 200 species, most of which occur as epiphytes in sub-saharan Africa. The three-lobed labellum of most Polystachya species possesses a fleshy callus and various types of trichomes and papillae. In this paper, we present the results of micromorphological studies on the labellum of 20 species, representing eight of the 13 sections in the genus, using scanning electron microscopy (SEM). Our results show the scale of infrageneric diversity of trichomes and papillae relative to the sampled sections. They also demonstrate the taxonomic value of labellar micromorphology at the sectional level. The study revealed seven types of papillae and five types of trichomes (uni- and multi-cellular) in Polystachya, some of which, are described here for the first time. Clavate trichomes are the most common and are present in 60% of the species studied. Moniliform trichomes mainly occur in sect. Polystachya and are strongly characteristic of the section. Pseudopollen is formed by fragmentation of moniliform trichomes or the detachment of other trichomes as bicellular units. We provide, for the first time, evidence for the detachment of the terminal cells of capitate trichomes.

Scanning Electron Microscopy Coupled with Energy Dispersive Spectrometric Analysis Reveals for the First Time Weddellite and Sylvite Crystals on the Surface of Involucral Bracts and Petals of two Xeranthemum L. (Compositae) Species

2017 ◽  
Vol 23 (3) ◽  
pp. 679-686 ◽  
Author(s):  
Milan Gavrilović ◽  
Suzana Erić ◽  
Petar D. Marin ◽  
Núria Garcia-Jacas ◽  
Alfonso Susanna ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Glandular Trichomes ◽  
Energy Dispersive ◽  
Spectrometric Analysis ◽  
Eds Analysis ◽  
Taxonomic Studies ◽  
First Time ◽  
Tetragonal Bipyramid ◽  
Scanning Electron

AbstractIn this work, weddellite and sylvite crystals are identified for the first time on the involucral bracts and petals of Xeranthemum annuum and Xeranthemum cylindraceum using scanning electron microscopy coupled with energy dispersive spectrometric (SEM-EDS) analysis. Well-developed crystals of weddellite (CaC2O4·2H2O) occur in the form of a tetragonal bipyramid (hhl), rarely in combination of a bipyramid and tetragonal prism (h00). Indumentum of involucral bracts of X. cylindraceum consists of nonglandular and glandular trichomes. Sylvite (KCl) crystals are observed only on the petal surface of X. cylindraceum. The crystals of sylvite occur in the form of perfect cubes (hexahedrons), but some crystals are deformed, i.e., partially elongated. Taxonomic significance of investigated microcharacters as well as the use of SEM-EDS analysis in taxonomic studies of plants are discussed.

scholarly journals Capture and scanning electron microscopy of individual snow crystals

1994 ◽  
Vol 40 (134) ◽  
pp. 195-197
Author(s):  
E. W. Wolff ◽  
A. P. Reid
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Liquid Nitrogen Temperature ◽  
Experimental Methods ◽  
Snow Crystal ◽  
Snow Crystals ◽  
First Time ◽  
Scanning Electron

AbstractA snow crystal has been successfully collected on to a scanning electron microscope (SEM) stub in central Greenland. It was preserved at liquid-nitrogen temperature for 5 months, prior to examination in the SEM. This is believed to be the first time a snow crystal has been observed directly in the SEM and offers some new experimental methods for understanding crystals and their chemistry.

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