Calcium and microtubule sliding in ciliary axonemes isolated from Paramecium caudatum

Microtubule sliding was induced in axonemes obtained from isolated cilia of Paramecium caudatum when they were exposed to a reactivating solution containing ATP after mild treatment with trypsin. Over a very wide range of concentrations (1 nM-4 mM), Ca2+ in the reactivating solution had no effect on the proportion of axonemes that disintegrated as the result of microtubule sliding. Also, the velocity of sliding, determined by cinematography, and the polarity of the direction of sliding-force generation, determined by electron microscopy with regards to the base-to-tip axis of the cilium, were not affected by Ca2+. The results indicate that the Ca sensitivity, which is responsible for the ciliary reversal response, was removed from the axoneme, possibly as the result of trypsin treatment. It is thus unlikely that Ca sensitivity is attributable to the basic sliding machinery that powers ciliary movement.

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Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070199 ◽

1978 ◽

Vol 36 (3) ◽

pp. 470-482 ◽

Cited By ~ 1

Author(s):

R.W. Horne

Keyword(s):

Electron Microscopy ◽

Image Processing ◽

Analytical Techniques ◽

Staining Technique ◽

High Resolution Electron Microscopy ◽

Optical Diffraction ◽

Full Potential ◽

Virus Particles ◽

Resolution Electron ◽

Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

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Microwaves: Application in Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158248 ◽

1990 ◽

Vol 48 (3) ◽

pp. 140-141

Author(s):

Anthony S-Y Leong ◽

David W Gove

Keyword(s):

Electron Microscopy ◽

Light Microscopy ◽

Chemical Reactions ◽

Electromagnetic Waves ◽

Tissue Fixation ◽

Primary Method ◽

Dipolar Molecules ◽

Wide Range ◽

Time Required ◽

Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

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Recent Progress and Plans in Computer-Controlled High Resolution Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010017952x ◽

1990 ◽

Vol 48 (1) ◽

pp. 154-155

Author(s):

W.J. de Ruijter ◽

Peter Rez ◽

David J. Smith

Keyword(s):

Electron Microscopy ◽

Digital Processing ◽

High Resolution Electron Microscopy ◽

Objective Lens ◽

Linear Filter ◽

Contrast Transfer Function ◽

Image Displacement ◽

Spatially Resolved ◽

Wide Range ◽

On Line

Digital computers are becoming widely recognized as standard accessories for electron microscopy. Due to instrumental innovations the emphasis in digital processing is shifting from off-line manipulation of electron micrographs to on-line image acquisition, analysis and microscope control. An on-line computer leads to better utilization of the instrument and, moreover, the flexibility of software control creates the possibility of a wide range of novel experiments, for example, based on temporal and spatially resolved acquisition of images or microdiffraction patterns. The instrumental resolution in electron microscopy is often restricted by a combination of specimen movement, radiation damage and improper microscope adjustment (where the settings of focus, objective lens stigmatism and especially beam alignment are most critical). We are investigating the possibility of proper microscope alignment based on computer induced tilt of the electron beam. Image details corresponding to specimen spacings larger than ∼20Å are produced mainly through amplitude contrast; an analysis based on geometric optics indicates that beam tilt causes a simple image displacement. Higher resolution detail is characterized by wave propagation through the optical system of the microscope and we find that beam tilt results in a dispersive image displacement, i.e. the displacement varies with spacing. This approach is valid for weak phase objects (such as amorphous thin films), where transfer is simply described by a linear filter (phase contrast transfer function) and for crystalline materials, where imaging is described in terms of dynamical scattering and non-linear imaging theory. In both cases beam tilt introduces image artefacts.

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A Highly Sensitive Room Temperature CO2 Gas Sensor Based on SnO2-rGO Hybrid Composite

Materials ◽

10.3390/ma14030522 ◽

2021 ◽

Vol 14 (3) ◽

pp. 522

Author(s):

Zhi Yan Lee ◽

Huzein Fahmi bin Hawari ◽

Gunawan Witjaksono bin Djaswadi ◽

Kamarulzaman Kamarudin

Keyword(s):

Electron Microscopy ◽

Carbon Dioxide ◽

Gas Sensor ◽

Photoelectron Spectroscopy ◽

Hybrid Composite ◽

Room Temperature ◽

Co2 Gas ◽

X Ray ◽

Wide Range ◽

Co2 Gas Sensor

A tin oxide (SnO2) and reduced graphene oxide (rGO) hybrid composite gas sensor for high-performance carbon dioxide (CO2) gas detection at room temperature was studied. Since it can be used independently from a heater, it emerges as a promising candidate for reducing the complexity of device circuitry, packaging size, and fabrication cost; furthermore, it favors integration into portable devices with a low energy density battery. In this study, SnO2-rGO was prepared via an in-situ chemical reduction route. Dedicated material characterization techniques including field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) were conducted. The gas sensor based on the synthesized hybrid composite was successfully tested over a wide range of carbon dioxide concentrations where it exhibited excellent response magnitudes, good linearity, and low detection limit. The synergistic effect can explain the obtained hybrid gas sensor’s prominent sensing properties between SnO2 and rGO that provide excellent charge transport capability and an abundance of sensing sites.

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Commercial Cokes and Graphites as Anode Materials for Lithium - Ion Cells

MRS Proceedings ◽

10.1557/proc-496-575 ◽

1997 ◽

Vol 496 ◽

Cited By ~ 1

Author(s):

David J. Derwin ◽

Kim Kinoshita ◽

Tri D. Tran ◽

Peter Zaleski

Keyword(s):

Electron Microscopy ◽

Ethylene Carbonate ◽

Average Particle Size ◽

Chemical Properties ◽

Lithium Ion ◽

Reversible Capacity ◽

Bet Surface Area ◽

Average Particle ◽

Electrochemical Characteristics ◽

Wide Range

AbstractSeveral types of carbonaceous materials from Superior Graphite Co. were investigated for lithium ion intercalation. These commercially available cokes, graphitized cokes and graphites have a wide range of physical and chemical properties. The coke materials were investigated in propylene carbonate based electrolytes and the graphitic materials were studied in ethylene carbonate / dimethyl solutions to prevent exfoliation. The reversible capacities of disordered cokes are below 230 mAh / g and those for many highly ordered synthetic (artificial) and natural graphites approached 372 mAh / g (LiC6). The irreversible capacity losses vary between 15 to as much as 200 % of reversible capacities for various types of carbon. Heat treated cokes with the average particle size of 10 microns showed marked improvements in reversible capacity for lithium intercalation. The electrochemical characteristics are correlated with data obtained from scanning electron microscopy (SEM), high resolution transmission electron microscopy (TAM), X - ray diffraction (XRD) and BET surface area analysis. The electrochemical performance, availability, cost and manufacturability of these commercial carbons will be discussed.

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Terbufos-sulfone exacerbates cardiac lesions in diabetic rats: a sub-acute toxicity study

Archives of Industrial Hygiene and Toxicology ◽

10.1515/aiht-2016-67-2776 ◽

2016 ◽

Vol 67 (2) ◽

pp. 126-135 ◽

Cited By ~ 3

Author(s):

Syed M. Nurulain ◽

Mohamed Shafiullah ◽

Javed Yasin ◽

Abdu Adem ◽

Juma Al Kaabi ◽

...

Keyword(s):

Electron Microscopy ◽

Organophosphorus Compounds ◽

Lethal Dose ◽

Density Lipoprotein ◽

Cardiac Effect ◽

Diabetic Rats ◽

Ultrastructural Changes ◽

Biochemical Tests ◽

Wide Range ◽

Cardiac Lesions

AbstractOrganophosphorus compounds (OPCs) have a wide range of applications, from agriculture to warfare. Exposure to these brings forward a varied kind of health issues globally. Terbufos is one of the leading OPCs used worldwide. The present study investigates the cardiac effect of no observable dose of a metabolite of terbufos, terbufos-sulfone (TS), under non-diabetic and streptozotocin-induced diabetic condition. One hundred nanomoles per rat (1/20 of LD50) was administered intraperitoneally to adult male Wister rats daily for fifteen days. The left ventricle was collected for ultrastructural changes by transmission electron microscopy. The blood samples were collected for biochemical tests including RBC acetylcholinesterase, creatinine kinase (CK), lactate dehydrogenase (LDH), cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), triglycerides, ALT, AST, and GGT. The study revealed about 10 % inhibition of RBC-AChE in two weeks of TS treatment in non-diabetic rats whereas RBC-AChE activity was significantly decreased in diabetic TS treated rats. CK, LDH, and triglycerides were significantly higher in diabetic TS treated rats. Electron microscopy of the heart showed derangement and lesions of the mitochondria of cardiomyocytes in the TS treated groups. The present study concludes that a non-lethal dose of TS causes cardiac lesions which exacerbate under diabetic condition. Biochemical tests confirmed the ultrastructural changes. It is concluded that a non-lethal dose of TS may be a risk factor for a cardiovascular disease, which may be fatal under diabetic condition.

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Application of Electron Backscatter Diffraction (EBSD) for Crystallographic Characterization of Aluminum-Doped Zinc Oxide Sputtered Films

Microscopy and Microanalysis ◽

10.1017/s143192761300113x ◽

2013 ◽

Vol 19 (S4) ◽

pp. 103-104

Author(s):

C.B. Garcia ◽

E. Ariza ◽

C.J. Tavares

Keyword(s):

Electron Microscopy ◽

Grain Size ◽

Zinc Oxide ◽

Electron Backscatter Diffraction ◽

Wide Range ◽

Electron Backscatter ◽

Aluminum Doped Zinc Oxide ◽

Ebsd Technique ◽

Backscatter Diffraction

Zinc Oxide is a wide band-gap compound semiconductor that has been used in optoelectronic and photovoltaic applications due to its good electrical and optical properties. Aluminium has been an efficient n-type dopant for ZnO to produce low resistivity films and high transparency to visible light. In addition, the improvement of these properties also depends on the morphology, crystalline structure and deposition parameters. In this work, ZnO:Al films were produced by d.c. pulsed magnetron sputtering deposition from a ZnO ceramic target (2.0 wt% Al2O3) on glass substrates, at a temperature of 250 ºC.The crystallographic orientation of aluminum doped zinc oxide (ZnO:Al) thin films has been studied by Electron Backscatter Diffraction (EBSD) technique. EBSD coupled with Scanning Electron Microscopy (SEM) is a powerful tool for the microstructural and crystallographic characterization of a wide range of materials.The investigation by EBSD technique of such films presents some challenges since this analysis requires a flat and smooth surface. This is a necessary condition to avoid any shadow effects during the experiments performed with high tilting conditions (70º). This is also essential to ensure a good control of the three dimensional projection of the crystalline axes on the geometrical references related to the sample.Crystalline texture is described by the inverse pole figure (IPF) maps (Figure 1). Through EBSD analysis it was observed that the external surface of the film presents a strong texture on the basal plane orientation (grains highlighted in red colour). Furthermore it was possible to verify that the grain size strongly depends on the deposition time (Figure 1 (a) and (b)). The electrical and optical film properties improve with increasing of the grain size, which can be mainly, attributed to the decrease in scattering grain boundaries which leads to an increasing in carrier mobility (Figure 2).The authors kindly acknowledge the financial support from the Portuguese Foundation for Science and Technology (FCT) scientific program for the National Network of Electron Microscopy (RNME) EDE/1511/RME/2005.

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Conserved mechanisms of microtubule-stimulated ADP release, ATP binding, and force generation in transport kinesins

eLife ◽

10.7554/elife.03680 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 69

Author(s):

Joseph Atherton ◽

Irene Farabella ◽

I-Mei Yu ◽

Steven S Rosenfeld ◽

Anne Houdusse ◽

...

Keyword(s):

Electron Microscopy ◽

Conformational Changes ◽

Catalytic Site ◽

Fundamental Question ◽

Force Generation ◽

Atp Binding ◽

Cellular Functions ◽

Microtubule Binding ◽

Cryo Electron Microscopy ◽

Adp Release

Kinesins are a superfamily of microtubule-based ATP-powered motors, important for multiple, essential cellular functions. How microtubule binding stimulates their ATPase and controls force generation is not understood. To address this fundamental question, we visualized microtubule-bound kinesin-1 and kinesin-3 motor domains at multiple steps in their ATPase cycles—including their nucleotide-free states—at ∼7 Å resolution using cryo-electron microscopy. In both motors, microtubule binding promotes ordered conformations of conserved loops that stimulate ADP release, enhance microtubule affinity and prime the catalytic site for ATP binding. ATP binding causes only small shifts of these nucleotide-coordinating loops but induces large conformational changes elsewhere that allow force generation and neck linker docking towards the microtubule plus end. Family-specific differences across the kinesin–microtubule interface account for the distinctive properties of each motor. Our data thus provide evidence for a conserved ATP-driven mechanism for kinesins and reveal the critical mechanistic contribution of the microtubule interface.

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Graphitic Nitrogen in Carbon Catalysts Important for the Reduction of Nitrite Revealed by 15N NMR Spectroscopy at Natural Abundance

10.26434/chemrxiv.12906227.v1 ◽

2020 ◽

Author(s):

Zheng Chen ◽

Aleksander Jaworski ◽

Jianhong Chen ◽

Tetyana Budnyak ◽

Ireneusz Szewczyk ◽

...

Keyword(s):

Electron Microscopy ◽

Photoelectron Spectroscopy ◽

Reduction Reaction ◽

Nitrite Reduction ◽

15N Nmr ◽

Carbon Catalyst ◽

X Ray ◽

Wide Range ◽

Alkaline Conditions

Metal-free nitrogen-doped carbon is considered as a green functional material, but the structural determination of the atomic positions of nitrogen remains challenging. We recently demonstrated that directly-excited solid state 15N NMR (ssNMR) spectroscopy is a powerful tool for the determination of such positions in an N-doped carbon at natural 15N isotope abundance. Here we present a green chemistry approach to the synthesis of N-doped carbon using cellulose as precursor, and a study of the catalytic properties and atomic structures of the related catalyst. The N-doped carbon (NH3) was obtained by oxidation of cellulose with HNO3 followed by ammonolysis at 800°C. It had a N content of 6.5 wt.% and a surface area of 557 m2 g–1, and 15N ssNMR spectroscopy provided evidence for graphitic nitrogen besides of regular pyrrolic and pyridinic nitrogen. This structure determination enabled probing the role of graphitic nitrogen for electrocatalytic reactions, such as the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and nitrite reduction reaction. The N-doped carbon catalyst (NH3) had higher electrocatalytic activities in OER and HER under alkaline conditions and a higher activity for nitrite reduction, as compared with a catalyst prepared by carbonization of the HNO3-treated cellulose in N2. The electrocatalytic selectivity for nitrite reduction of the N-doped carbon catalyst (NH3) was directly related to the graphitic nitrogen functions. Complementary structural analysis by means of 13C and 1H ssNMR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and low-temperature N2 adsorption were preformed and provided support to the findings. The results show that directly-excited 15N ssNMR at natural 15N abundance is generally capable to provide information on N-doped carbon materials, and it is expected that the approach can be applied to a wide range of solids with an intermediate amount of N atoms.

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Delamination Behavior of Cu-Low-k Stack Under Different Slurries

MRS Proceedings ◽

10.1557/proc-767-f7.3 ◽

2003 ◽

Vol 767 ◽

Author(s):

A. K. Sikder ◽

S. Thagella ◽

P. B. Zantye ◽

Ashok Kumar

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Chemical Mechanical Polishing ◽

Wear Behavior ◽

Polished Surface ◽

Cu Metallization ◽

Wide Range ◽

Low K ◽

Delamination Behavior ◽

Scanning Electron

AbstractLower mechanical strength, reduced cohesive strength and lack of compatibility with other interconnect materials, are the major challenges involved in chemical mechanical polishing (CMP) of Cu metallization with ultra low-k materials as interlayer dielectrics. In this study we have investigated the polishing behavior of patterned Cu samples with underneath different low-k materials using two different slurries and a wide range of machine parameters. CMP micro tribometer was used to polish the samples with different rotations of platen (50 to 250 RPM) and down forces (1-6 PSI). Friction co-efficient and wear behavior were also investigated at different conditions. Optical and scanning electron microscopy was used to investigate the polished surface. It was observed that the two different Cu slurries used for polishing have marked effects on the polishing of Cu-low-k stack with respect to wear and delamination.

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