scholarly journals Effects of external surface charges on the enhanced piezoelectric potential of ZnO and AlN nanowires and nanotubes

AIP Advances ◽  
2012 ◽  
Vol 2 (4) ◽  
pp. 042174 ◽  
Author(s):  
Seong Min Kim ◽  
Hyeok Kim ◽  
Youngmin Nam ◽  
Sungjin Kim
Keyword(s):  
External Surface ◽  
Surface Charges ◽  
Piezoelectric Potential

Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra

1971 ◽  
Vol 29 ◽  
pp. 410-411 ◽  
Author(s):  
Jane A. Westfall ◽  
S. Yamataka ◽  
Paul D. Enos
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Osmium Tetroxide ◽  
External Surface ◽  
Three Dimensional ◽  
Surface Structures ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Scanning Electron

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).

High-resolution gold labeling

1993 ◽  
Vol 51 ◽  
pp. 330-331
Author(s):  
James F. Hainfeld ◽  
Frederic R. Furuya ◽  
Kyra Carbone ◽  
Martha Simon ◽  
Beth Lin ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Polypeptide Chain ◽  
External Surface ◽  
Gold Cluster ◽  
Macromolecular Complex ◽  
Gold Compound ◽  
Central Cavity ◽  
Chain Folding ◽  
E Coli ◽  
Chaperonin Groel

A recently developed 1.4 nm gold cluster has been found to be useful in labeling macromolecular sites to 1-3 nm resolution. The gold compound is organically derivatized to contain a monofunctional arm for covalent linking to biomolecules. This may be used to mark a specific site on a structure, or to first label a component and then reassemble a multicomponent macromolecular complex. Two examples are given here: the chaperonin groEL and ribosomes.Chaperonins are essential oligomeric complexes that mediate nascent polypeptide chain folding to produce active proteins. The E. coli chaperonin, groEL, has two stacked rings with a central hole ∽6 nm in diameter. The protein dihydrofolate reductase (DHFR) is a small protein that has been used in chain folding experiments, and serves as a model substrate for groEL. By labeling the DHFR with gold, its position with respect to the groEL complex can be followed. In particular, it was sought to determine if DHFR refolds on the external surface of the groEL complex, or whether it interacts in the central cavity.

ELECTROHYDRODYNAMIC INSTABILITY OF LIQUID SHEET SATURATING POROUS MEDIUM WITH INTERFACIAL SURFACE CHARGES

2013 ◽  
Vol 23 (2) ◽  
pp. 165-191
Author(s):  
Mohamed F. El-Sayed ◽  
M. H. M. Moussa ◽  
Ahmed A. A. Hassan ◽  
N. M. Hafez
Keyword(s):  
Porous Medium ◽  
Liquid Sheet ◽  
Surface Charges ◽  
Electrohydrodynamic Instability ◽  
Interfacial Surface

Kerusakan Pada Material Pipa Air Bersih Akibat General Corrosion

2019 ◽  
Vol 16 (2) ◽  
Author(s):  
M. N. Setia Nusa
Keyword(s):  
Chemical Composition ◽  
Failure Analysis ◽  
External Surface ◽  
Internal Surface ◽  
General Corrosion ◽  
Water Pipe ◽  
Corrosion Attack ◽  
Corrosion Failure ◽  
Environment Factor

Water pipe of 4.5” diameter and has been operated for 8 year having failure due to corrosion attack on its external and internal surface. It is conducted failure analysis to find out the cause of corrosion by having testing examination of visual fractography, metalography,, SEM EDAX, hardness and chemical composition. Testing and examination results show that the failure / corroded pipe has a for in of general corrosion on the external surface due to environment factor or ground factor arround the pipe and on the internal surface was influenced by excessive root weld creating protrude which then causing turbolens and deposite to accelerate corrosion attack.Pipa berdiameter 4.5” yang berfungsi mengalirkan air bersih dan telah beroperasi selama 8 tahun, terjadi kerusakan berbentuk korosi pada permukaan luar pipa dan permukaan dalam. Untuk itu dilakukan analisa kerusakan untuk mengetahui penyebab terjadinya korosi dengan pengujian dan pemeriksaan secara visual,Fractography, Metallography, SEM, EDAX, Uji Kekerasan dan Uji Komposisi Kimia. Hasil pemeriksaan dan pengujian pada pipa yang rusak / korosi berbentuk jenis general korosi pada permukaan luar pipa yang diakibatkan faktor lingkungan atau tanah disekitar pipa, sedangkan pada bagian dalam pipa dipengaruhi oleh adanya lelehan pengelasan yang kurang sempurna sehingga menimbulkan benjolan yang mengakibatkan aliran air didalam pipa tidak lancar sehingga terjadi turbolensi yang menimbulkan endapan dan mengakibatkan percepatan terjadinya korosi.Keywords: Pipe, environtment, turbolens, corrosion, failure

TECHNOLOGICAL CONTROL OF THE CONTACT PRESSURE ON THE CYLINDRICAL SUBSTRATE FROM THE SIDE OF THE COATING ADDITIVELY FORMED ON ITS EXTERNAL SURFACE

2020 ◽  
Author(s):  
Dmitriy Parshin
Keyword(s):  
Stress State ◽  
Contact Pressure ◽  
Mechanical Model ◽  
External Surface ◽  
Layer By Layer ◽  
Layer Formation ◽  
Technological Control ◽  
Manufactured Products ◽  
Arbitrary Thickness

The article gives an example of controlling the stress state parameters of additively manufactured products. The study was carried out on the basis of a developed non-classical mechanical model of the process of layer-by-layer formation of a coating of arbitrary thickness on a cylindrical substrate. The model is based on modern concepts of the mechanics of continuously growing bodies and allows one to obtain fairly simple analytical dependencies. On the basis of the latter, the problem of technological control of the evolution of contact pressure at the substrate – coating interface is solved in the article. A number of practically significant conclusions have been made.

Carboxymethyl-hexanoyl Chitosan Nanodroplets for Ultrasonic Imaging and Drug Delivery to Tumor

2018 ◽  
Vol 24 (15) ◽  
pp. 1682-1688 ◽  
Author(s):  
Yu Jinsui ◽  
Situ Bing ◽  
Luo Muhua ◽  
Li Yue ◽  
Liao Jianyi ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
Tumor Therapy ◽  
Carboxymethyl Chitosan ◽  
Great Promise ◽  
Ovarian Cancer Cells ◽  
Mechanical Index ◽  
Surface Charges ◽  
Particle Structure ◽  
Drug Release Profile ◽  
Hexanoyl Chitosan

Introduction: Although a great many strategies have been proposed for tumor-targeted chemotherapy, current delivery methods of anticancer drugs present limited success with inevitable systemic toxicity. The aim of this study was to develop a new kind of theranostic carrier for targeted tumor therapy. Methods: Prior to prepare CHC-PFP-DOX, carboxymethyl-hexanoyl chitosan (CHC) was synthesized by acylation of carboxymethyl chitosan. To develop CHC-PFP, perfluoropentane (PFP), an ultrasound gas precursor, was simultaneously encapsulated into the hydrophobic inner cores of pre-formulated CHC micelle in aqueous phase via using the oil in water (O/W) emulsion method. The size distribution and surface charges of these nanodroplets were measured and the morphology was observed by transmission electron microscopy (TEM). For ultrasound imaging application, in vitro model was established to evaluate the imaging of CHC-PFP-DOX under different concentration and mechanical index. After that, the anti-tumor effect of ultrasound combined with CHC-PFPDOX on ovarian cancer cells was investigated. Results: The resulting CHC-PFP-DOX had a nano-sized particle structure, with hydrophobic anticancer DOX/PFP inner cores and a hydrophilic carboxymethyl chitosan polymer outer shell. The favorable nano-scaled size offers the potential to extravagate from veins and accumulate in tumor tissues via enhanced permeation and retention (EPR) effect. Additionally, CHC-PFP-DOX showed the ability to serve as ultrasound imaging agent at body temperature. Notably, it exhibited an ultrasound-triggered drug release profile through the external ultrasound irradiation. Further study demonstrated that ultrasound combined with CHC-PFP-DOX can improve the killing effect of chemotherapy for tumor. Conclusion: CHC-PFP-DOX holds great promise in simultaneous cancer-targeting ultrasound imaging and ultrasound- mediated delivery for cancer chemotherapy.

Evaluation of Surface-modified Superparamagnetic Iron Oxide Nanoparticles to Optimize Bacterial Immobilization for Bio-separation with the Least Inhibitory Effect on Microorganism Activity

2020 ◽  
Vol 10 (2) ◽  
pp. 166-174
Author(s):  
Mehdi Khoshneviszadeh ◽  
Sarah Zargarnezhad ◽  
Younes Ghasemi ◽  
Ahmad Gholami
Keyword(s):  
Iron Oxide ◽  
Amino Acid ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Surface Coating ◽  
Superparamagnetic Iron Oxide ◽  
Superparamagnetic Iron Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Surface Charges ◽  
Surface Modified

Background: Magnetic cell immobilization has been introduced as a novel, facile and highly efficient approach for cell separation. A stable attachment between bacterial cell wall with superparamagnetic iron oxide nanoparticles (SPIONs) would enable the microorganisms to be affected by an outer magnetic field. At high concentrations, SPIONs produce reactive oxygen species in cytoplasm, which induce apoptosis or necrosis in microorganisms. Choosing a proper surface coating could cover the defects and increase the efficiency. Methods: In this study, asparagine, APTES, lipo-amino acid and PEG surface modified SPIONs was synthesized by co-precipitation method and characterized by FTIR, TEM, VSM, XRD, DLS techniques. Then, their protective effects against four Gram-positive and Gram-negative bacterial strains including Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were examined through microdilution broth and compared to naked SPION. Results: The evaluation of characterization results showed that functionalization of magnetic nanoparticles could change their MS value, size and surface charges. Also, the microbial analysis revealed that lipo-amino acid coated magnetic nanoparticles has the least adverse effect on microbial strain among tested SPIONs. Conclusion: This study showed lipo-amino acid could be considered as the most protective and even promotive surface coating, which is explained by its optimizing effect on cell penetration and negligible reductive effects on magnetic properties of SPIONs. lipo-amino acid coated magnetic nanoparticles could be used in microbial biotechnology and industrial microbiology.

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