Sporopollenin Nanostructure of Ilex paraguariensis A.St.Hil Pollen Grains

2005 ◽  
Vol 11 (S03) ◽  
pp. 78-81
Author(s):  
R. P. Santos ◽  
L. M. Rebelo ◽  
E. F. Costa ◽  
A. A. X. Santiago ◽  
V. N. Freire ◽  
...  
Keyword(s):  
Pollen Grains ◽  
Point Of View ◽  
Ilex Paraguariensis ◽  
Spores And Pollen ◽  
Coarse Powder ◽  
Force Microscopy ◽  
Male Gametes ◽  
Atomic Force ◽  
Ideal Method ◽  
Pollen Grain Wall

Pollens appear like a fine to coarse powder that is liberated by the microsporangia of Gimnosperms and Angiosperms. The pollen grain wall, the sporoderm, envelopes the microgametophytes (male gametophytes), which produce the male gametes of seed plants. Pollen grains are interesting from the material science point of view since the native polymer, the sporopollenin, found in the sporoderm outer layer (exine), is one of the toughest known materials which is degraded by oxidation but is resistant to reduction. This property permits the sporopollenin persistence as an unaltered polymer in sediments of great age, e.g the Ordovician period, 400 million years ago. Sporopollenin is a mixture of fatty acids, phenyl-derivatives as p-coumaric acid, and carotenes [1]. Its nanostructure is not yet completed revealed. Therefore, more studies must be performed. A number of models have been proposed for the sporopollenin nanostructure of spores and pollen grains [2]. Rowley et al. [3-4] interpret exine structure as being formed by helical subunits, based on transmission and scanning electron microscope (TEM and SEM) studies. The atomic force microscopy (AFM) is the ideal method to study the sporopollenin nanostructure [5] since the arrangement of components is not visualized easily through other microscope techniques (e.g. TEM and SEM). In the present work, we used AFM to study the sporopollenin nanostructure of the Ilex paraguariensis A.St.Hil. exine, an Angiosperm (Aquifoliaceae).

scholarly journals Detection Limits of DLS and UV-Vis Spectroscopy in Characterization of Polydisperse Nanoparticles Colloids

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Emilia Tomaszewska ◽  
Katarzyna Soliwoda ◽  
Kinga Kadziola ◽  
Beata Tkacz-Szczesna ◽  
Grzegorz Celichowski ◽  
...  
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Point Of View ◽  
Spectroscopy Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
The One

Dynamic light scattering is a method that depends on the interaction of light with particles. This method can be used for measurements of narrow particle size distributions especially in the range of 2–500 nm. Sample polydispersity can distort the results, and we could not see the real populations of particles because big particles presented in the sample can screen smaller ones. Although the theory and mathematical basics of DLS technique are already well known, little has been done to determine its limits experimentally. The size and size distribution of artificially prepared polydisperse silver nanoparticles (NPs) colloids were studied using dynamic light scattering (DLS) and ultraviolet-visible (UV-Vis) spectroscopy. Polydisperse colloids were prepared based on the mixture of chemically synthesized monodisperse colloids well characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), DLS, and UV-Vis spectroscopy. Analysis of the DLS results obtained for polydisperse colloids reveals that several percent of the volume content of bigger NPs could screen completely the presence of smaller ones. The presented results could be extremely important from nanoparticles metrology point of view and should help to understand experimental data especially for the one who works with DLS and/or UV-Vis only.

scholarly journals Physics Comes to the Aid of Medicine—Clinically-Relevant Microorganisms through the Eyes of Atomic Force Microscope

Pathogens ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 969
Author(s):  
Mateusz Cieśluk ◽  
Piotr Deptuła ◽  
Ewelina Piktel ◽  
Krzysztof Fiedoruk ◽  
Łukasz Suprewicz ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Antimicrobial Agents ◽  
Antimicrobial Treatment ◽  
Point Of View ◽  
Diagnostic Methods ◽  
Drug Resistant ◽  
Bacterial Strains ◽  
Force Microscopy ◽  
Atomic Force ◽  
Recent Developments

Despite the hope that was raised with the implementation of antibiotics to the treatment of infections in medical practice, the initial enthusiasm has substantially faded due to increasing drug resistance in pathogenic microorganisms. Therefore, there is a need for novel analytical and diagnostic methods in order to extend our knowledge regarding the mode of action of the conventional and novel antimicrobial agents from a perspective of single microbial cells as well as their communities growing in infected sites, i.e., biofilms. In recent years, atomic force microscopy (AFM) has been mostly used to study different aspects of the pathophysiology of noninfectious conditions with attempts to characterize morphological and rheological properties of tissues, individual mammalian cells as well as their organelles and extracellular matrix, and cells’ mechanical changes upon exposure to different stimuli. At the same time, an ever-growing number of studies have demonstrated AFM as a valuable approach in studying microorganisms in regard to changes in their morphology and nanomechanical properties, e.g., stiffness in response to antimicrobial treatment or interaction with a substrate as well as the mechanisms behind their virulence. This review summarizes recent developments and the authors’ point of view on AFM-based evaluation of microorganisms’ response to applied antimicrobial treatment within a group of selected bacteria, fungi, and viruses. The AFM potential in development of modern diagnostic and therapeutic methods for combating of infections caused by drug-resistant bacterial strains is also discussed.

Palynostratigraphy and palaeoclimate of the Valanginian– Cenomanian subsurface succession in Hamza-1X well, Matruh Basin, Egypt

2020 ◽  
Vol 297 (2) ◽  
pp. 173-191 ◽  
Author(s):  
Ibrahim M. Ied ◽  
Sameh S. Tahoun ◽  
Walid A. Makled
Keyword(s):  
Age Determination ◽  
Pollen Grains ◽  
Point Of View ◽  
Western Desert ◽  
Dinoflagellate Cysts ◽  
Spores And Pollen ◽  
Dinoflagellate Cyst ◽  
The North ◽  
Assemblage Zone ◽  
Stratigraphic Succession

Diverse palynomorph assemblages of spores, pollen grains and dinoflagellate cysts have been yielded from the palynological analyses of 115 ditch cutting samples covering the Valanginian– Cenomanian succession encountered in Hamza-1X well, Matruh Basin, north Egypt. The complex sit- uations in the north Western Desert requires more revisited palynozones for better understanding of the subsurface successions therein. Consequently, the first downhole palyno-events will be very helpful in solving some issues concerning the age determination and correlation. Seventy palynomorph species (47 spores and pollen grains; 23 dinoflagellate cyst species) were identified from all the productive samples which used to divide the studied succession into numerous sporomorph and dinoflagellate biozones based on the last occurrence datum for the recovered marker taxa. Four sporomorph inter- val biozones and six dinoflagellate cyst interval biozones were differentiated from the same studied stratigraphic succession. The four sporomorph biozones are presented, in ascending order as follows: Aequitriradites spinulosus and Impardecispora apiverrucata Interval Zone (late Valanginian– early Barremian), Pilosisporites trichopapillosus I. Z. (late Barremian), Murospora florida I. Z. (early Aptian–late Aptian), and Elaterosporites klaszii I. Z. (early Albian– early Cenomanian). The seven dinoflagellate cysts biozones are Muderongia simplex I. Z. (late Valanginian–early Barremian), Pseudoceratium anaphrissum I. Z. (late Barremian– early Aptian), Cribroperidinium edwardsii I. Z. (early Aptian), Subtilisphaera perlucida I. Z. (late Aptian), Oligosphaerdium complex I. Z. (early– late Albian), Dinopterygium cladoides and Coronifera oceanica Assemblage Zone (early Cenomanian). From the palaeoclimatic point of view, the studied interval could be differentiated into two climatic intervals; the lower arid interval that comprises the Alam El Bueib Formation and dominated by the arid xerophyte elements like Sphaeripollenites and Classopollis. The upper humid interval represents the Alamein, Dahab, Kharita and Bahariya formations that is dominated by the humid hygrophyte elements, such as Murospora, Crybeolsporites, Elaterosporites, Afropollis and Deltoidospora.

High Resolution DNA Imaging by Dynamic Atomic Force Microscopy: The Effect of the Substrate and Sample Preparation

2014 ◽  
Vol 1652 ◽  
Author(s):  
Tzu-Chieh Tang ◽  
Carlo A. Amadei ◽  
Matteo Chiesa
Keyword(s):  
Atomic Force Microscopy ◽  
Metal Ions ◽  
Physicochemical Characteristics ◽  
Temporal Variations ◽  
Point Of View ◽  
Ion Distribution ◽  
Nickel Ion ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Profile

ABSTRACTAdsorption of charged biomolecules onto atomically flat mica substrates is facilitated by the deposition of metal ions. Despite successfully acting as preferential anchoring sites, the presence of ions on the mica surface also changes its physicochemical characteristics something that is rarely quantified from a nanoscale point of view. In this study the nanoscale physicochemical properties of nickel-functionalized Muscovite mica are investigated by reconstructing the conservative force profile between an atomic force microscopy (AFM) tip and the surface. Various nickel ion concentrations (i.e. 1.0 mM to 20.0 mM) along with different incubation times (30 seconds and 5 minutes) are directly analyzed. Details in the spatial and temporal variations in surface properties due to the ion mediated adsorption of water are presented in details and in light of the binding efficiency of the metal ions. This insight benefits our understanding in the behavior of ion distribution that plays a crucial role in biomolecule imaging using AFM.

Non-Thermal Plasma Aided Soil Decontamination

2013 ◽  
Vol 16 (1) ◽  
Author(s):  
Henryka D. Stryczewska ◽  
Joanna Pawłat ◽  
Kenji Ebihara
Keyword(s):  
Point Of View ◽  
Treatment Technique ◽  
Soil Decontamination ◽  
Chemical Methods ◽  
Force Microscopy ◽  
Atomic Force ◽  
Biological Phenomena ◽  
Dna Strands ◽  
Non Thermal Plasma ◽  
Short Time

AbstractLow temperature atmospheric pressure plasmas (LTPs) together with advanced oxidation processes (AOPs) are alternative to conventional chemical methods of soil decontamination. The processing of soil itself depends on several factors, like type of soil and pollutants, treatment technique, geological and atmospheric circumstances. In the paper problems of soil, water, buildings, farms, land, and housing contaminations after floods and ecological disasters have been introduced. Plasma aided techniques together with AOPs have been presented from the point of view of decontamination potential as well as their impact on soil properties and fertility. Additionally, nanosize biological phenomena occurring in DNA strands during ozonation were visualized. The reaction of ozone with DNA is essential to understand the sterilization in agricultural soil. The structural images of the DNA samples were taken with the atomic force microscopy (AFM). It was shown that highly concentrated ozone broke hydrogen bonding of nuclei bases of DNA in relatively short time.

scholarly journals Study of the Electrical Properties of Porous Silicon Prepared by Electrochemical Etching Technique

2019 ◽  
Vol 54 (5) ◽  
Author(s):  
Warood Kream Alaarage ◽  
Luma Hafedh Abed Oneiza ◽  
Mohanad Ghulam Murad Alzubaidi
Keyword(s):  
Electrical Properties ◽  
Porous Silicon ◽  
Ideality Factor ◽  
Thermal Emission ◽  
Electrochemical Etching ◽  
Point Of View ◽  
Etching Technique ◽  
Force Microscopy ◽  
Atomic Force ◽  
P Type

In our work, a P-type porous silicon (PSi) with orientation (100) have been prepared using the chemical etching method; the goal is to study the electrical properties of PSi samples prepared with completely different etching current (7, 9, 11 and 13) mA and glued for (15 min) anodization time. Depending on the atomic force microscopy (AFM) investigation, we notice the roughness of Si surface increases with increasing etching current because of increases within the dimension (diameter) of surface pits. The electrical and optoelectronic properties of prepared PSi, specifically capacitance-voltage (C-V), current-voltage (I-V), responsivity and detectivity, are analyzed. It had been found that electrical characteristics of porous Si samples measured in dark (Id) and below illumination (IPh) will be fitted well by the equations of thermal emission. From this point of view, Schottky barrier height (ɸB) and ideality factor (n) of made-up photodetectors were calculated. We tended to determine from I-V characteristics of a dark, and illuminations that the pass current through the PSi layer reduced by increasing the etching current, as a result of increasing the electrical resistance of PSi layer and therefore the optimum value of ideality factor is (2.7), whereas from C-V characteristic we determined that in-built potential accumulated with increasing etching current. The results show that there are clear results for better performance of photodetectors.

scholarly journals The atypically high modulus of pollen exine

2018 ◽  
Vol 15 (146) ◽  
pp. 20180533 ◽  
Author(s):  
Zihao Qu ◽  
J. Carson Meredith
Keyword(s):  
Elastic Modulus ◽  
Poa Pratensis ◽  
Pollen Grains ◽  
Kentucky Bluegrass ◽  
Ambrosia Artemisiifolia ◽  
Ragweed Pollen ◽  
Force Microscopy ◽  
Pollen Exine ◽  
Atomic Force ◽  
Reinforcing Fillers

Sporopollenin, the polymer comprising the exine (outer solid shell) of pollen, is recognized as one of the most chemically and mechanically stable naturally occurring organic substances. The elastic modulus of sporopollenin is of great importance to understanding the adhesion, transport and protective functions of pollen grains. In addition, this fundamental mechanical property is of significant interest in using pollen exine as a material for drug delivery, reinforcing fillers, sensors and adhesives. Yet, the literature reports of the elastic modulus of sporopollenin are very limited. We provide the first report of the elastic modulus of sporopollenin from direct indentation of pollen particles of three plant species: ragweed ( Ambrosia artemisiifolia ), pecan ( Carya illinoinensis ) and Kentucky bluegrass ( Poa pratensis ). The modulus was determined with atomic force microscopy by using direct nanomechanical mapping of the pollen shell surface. The moduli were atypically high for non-crystalline organic biomaterials, with average values of 16 ± 2.5 GPa (ragweed), 9.5 ± 2.3 GPa (pecan) and 16 ± 4.0 GPa (Kentucky bluegrass). The amorphous pollen exine has a modulus exceeding known non-crystalline biomaterials, such as lignin (6.7 GPa) and actin (1.8 GPa). In addition to native pollen, we have investigated the effects of exposure to a common preparative base–acid chemical treatment and elevated humidity on the modulus. Base–acid treatment reduced the ragweed modulus by up to 58% and water vapour exposure at 90% relative humidity reduced the modulus by 54% (pecan) and 72% (Kentucky bluegrass). These results are in agreement with recently published estimates of the modulus of base–acid-treated ragweed pollen of 8 GPa from fitting to mechanical properties of ragweed pollen–epoxy composites.

Nanodynamics of Vapor-Phase Organophosphates on Silicon and OTS for MEMS Lubrication Purposes

2005 ◽  
Author(s):  
W. Neeyakorn ◽  
S. M. Lee ◽  
O. Parker ◽  
J. E. Burnette ◽  
L. S. Bilbro ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Polycrystalline Silicon ◽  
Quartz Crystal ◽  
Point Of View ◽  
Morphological Properties ◽  
Deposition Method ◽  
Mems Devices ◽  
Gold Surfaces ◽  
Force Microscopy ◽  
Atomic Force

We have performed a quartz crystal microbalance (QCM) study of the nanotribological properties of organophosphate (tricresylphosphate and t-butyl phenylphosphate) layers adsorbed from the vapor phase onto silicon (amorphous silicon and MEMS-like polysilicon), and octadecyltrichlorosilane (OTS) treated silicon and gold surfaces. The latter systems have been studied in order to explore whether organophosphates and OTS in combination might prove synergistic from a tribological point of view [1]. There is a strong possibility that this combination will also exhibit synergistic tribological behaviors when tested on actual MEMS devices. Therefore, it is important to perform QCM measurement on silicon that is as close to that of MEMS devices. In order to perform this study, we have developed a deposition method involving a Si-Ge layer that enables the growth of polycrystalline silicon on top of Cu QCM electrodes. The structural and morphological properties of these samples have been characterized with Raman spectroscopy and atomic force microscopy (AFM), confirming that they are similar in nature to the silicon in actual MEMS devices.

scholarly journals Quest for improving service life of asphalt roads

2020 ◽  
Vol 4 ◽  
pp. 154-162
Author(s):  
Manfred N. Partl
Keyword(s):  
Service Life ◽  
Building Materials ◽  
Phase Change Materials ◽  
Material Design ◽  
Point Of View ◽  
Asphalt Pavements ◽  
Force Microscopy ◽  
The Road ◽  
Atomic Force ◽  
Materials Recycling

Selected results and initiatives in modern asphalt pavement research for increasing service life of asphalt pavements under the aspect of sustainability and multifunctional use of roads are summarized. Focus lies on innovative approaches and own experience, jointly elaborated during the last decades within the road engineering/sealing components lab at Empa and both the highway/railways engineering and building materials group at KTH. This includes material concepts and design as well as pavement system and construction aspects from an experimental and modelling point of view. It includes also the application of powerful experimental and computational tools, such as Atomic-Force-Microscopy (AFM), X-Ray-Computer-Tomography (CT), Digital-Imaging-Correlation (DIC) and Discrete-Element-Method (DEM). As for materials, recycling issues and the use of Phase-Change-Materials (PCM) or metallic ingredients for inductive thermal crack healing are addressed. In order to remind that material design must also account for the workability during the process of compaction, the new Compaction-Flow-Test (CFT) developed at KTH is shortly presented. Innovative ideas for structural material composition are also mentioned, such as “artificial aggregates” or “additive manufacturing”, being aware that there is still a long way to go. Regarding pavement systems, ideas for multifunctional road applications are proposed. Focus is also put on special issues, such as construction joints.

Stressed States and Self-Organized Structuring of W/C Multilayers

2001 ◽  
Vol 695 ◽  
Author(s):  
D.C. Meyer ◽  
A. Klingner ◽  
T. Leisegang ◽  
Th. Holz ◽  
R. Dietsch ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Mechanical Stability ◽  
Point Of View ◽  
Mountain Range ◽  
X Ray ◽  
Force Microscopy ◽  
Additional Information ◽  
Mechanical Constraints ◽  
Self Organized ◽  
Atomic Force

ABSTRACTCharacterization and quantitative analysis of stressed states of a series of W/C multilayers (10-40 periods prepared by pulsed laser deposition on Si (111) substrates of different thickness) were carried out by means of X-ray reflectometry, wide angle diffractometry and a novel laser mapping device. As the W/C multilayers were dedicated to technical applications as X-ray optics and subjected to optimization of stacking parameters (thickness and number of layers) for a long term (mechanical) stability also further investigations will be discussed. Comparison of wafer distortion as evaluated by laser scanning and strain of the W layer as deduced from X-ray diffraction let us conclude that W layers are under compressive and C layers under tensile stress. The investigation of the thermally stimulated relaxation behavior of the multilayers provided a confirmation of these results. Additional information could be obtained by comparative relaxation experiments under external mechanical constraints. Furthermore, we report on a self-organized process of structuring of the multilayers under investigation, which might be of interest also from a technical point of view. The entire surface area (diameter 2') could be converted from the smooth (as-deposited) to a structured (relaxed) state stable at room temperature. Investigations using optical and atomic force microscopy showed that the topology of the surface consists of a mountain range where the valleys are on the level of the as-deposited non-debonded surface and that long wrinkled ridges of about the same height run along arbitrary directions.

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