Metal-Assisted Etching of Silicon: Activity of Metal Catalysts and Control of Porous Structure

2015 ◽  
Keyword(s):  
Porous Structure ◽  
Metal Catalysts ◽  
And Control ◽  
Silicon Activity

scholarly journals Open porous morphology evolution in poly (butylene succinate)/chitin nanocrystal nanocomposite foams

2021 ◽  
Author(s):  
Hai Fu ◽  
Dexian Yin ◽  
Tianhao Wang ◽  
Wei Gong ◽  
Hongfu Zhou
Keyword(s):  
Porous Structure ◽  
Pore Wall ◽  
Crystalline Polymer ◽  
Butylene Succinate ◽  
Sulfuric Acid Treatment ◽  
Nanocomposite Foams ◽  
Biodegradable Poly ◽  
Open Porous Structure ◽  
Foaming Temperature ◽  
And Control

Abstract In recent decades, biodegradable polymeric open-porous foams have been engaging increasing interests owing to their biodegradability, porosity and biocompatibility. In this work, biodegradable poly (butylene succinate) (PBS)/chitin nanocrystals (ChNCs) nanocomposite foams with open porous structure were successful fabricated by a solid-state batch foaming method. ChNCs were obtained from chitin by using sulfuric acid treatment and then introduced into PBS. The incorporation of ChNCs had a positive effect on the crystallization behaviors, melt viscoelasticity and thermal stability of diverse PBS specimens. Compared with the change of foaming temperature, the addition of ChNCs would cause a prominent influence on the open porous structure of diverse PBS foams. The probable explanation was that during the foaming process, the spherulites and/or ChNCs as the hard region in PBS could be served as pore wall and the amorphous area as the soft region was acted as pore, leading to open porous PBS foams. The reported strategy in this work could provide the guidelines to regulate and control open porous foams in other semi-crystalline polymer matrices.

scholarly journals Energy Divider with Insert for Heat Protection of Fruit Trees

2018 ◽  
Vol 21 (1) ◽  
pp. 8-13
Author(s):  
Alexander Genbach ◽  
Nellya Jamankulova ◽  
Hristo Beloev ◽  
Iliya Iliev
Keyword(s):  
Porous Structure ◽  
Economic Impacts ◽  
Fruit Trees ◽  
Soil Freezing ◽  
Operating Pressure ◽  
Heat Protection ◽  
Ring Channel ◽  
The Republic ◽  
Protection And Control ◽  
And Control

Abstract The method of heat protection and control of phenophases of fruit trees by means of a ring energy divider with insert in the zones of risky agriculture has been developed. This method is performed on the principle of a heat pipe (thermosyphon) or thermopile working in the device of a ring energy divider. The naturally circulating coolant can change the aggregate state, and the presence of a capillary porous structure in the ring channel facilitates the efficient transport of the liquid. The problem of soil freezing was solved as a task of a semi-infinite solid body, when the heat flux passing through the surface of the soil was about 5 W∙m−2, and the driving pressure was −9 °C. The operating pressure is established, the temperature profile is measured, and the coolant consumption and the type of porous structure are optimised. The economic impacts on one tree will make approximately $50, and for a fruit zone of the Republic of Kazakhstan, the economic impacts exceed 500 million dollars per year.

Construction and control of 3D porous structure based on vapor deposition on sublimation solids

2017 ◽  
Vol 7 ◽  
pp. 77-81 ◽  
Author(s):  
Hsing-Ying Tung ◽  
Ting-Pi Sun ◽  
Ho-Yi Sun ◽  
Zhen-Yu Guan ◽  
Shu-Kai Hu ◽  
...  
Keyword(s):  
Porous Structure ◽  
Vapor Deposition ◽  
And Control

Control of Metal Alloy Oxidation with Electric Fields

1973 ◽  
Vol 31 ◽  
pp. 164-165
Author(s):  
R. R. Dils ◽  
P. S. Follansbee
Keyword(s):  
Electric Fields ◽  
Oxidation Process ◽  
Base Alloy ◽  
Oxide Surface ◽  
Platinum Electrodes ◽  
Insulating Layer ◽  
Iron Base Alloy ◽  
Alloy Oxidation ◽  
Aluminum Oxide Layer ◽  
And Control

Electric fields have been applied across oxides growing on a high temperature alloy and control of the oxidation of the material has been demonstrated. At present, three-fold increases in the oxidation rate have been measured in accelerating fields and the oxidation process has been completely stopped in a retarding field.The experiments have been conducted with an iron-base alloy, Pe 25Cr 5A1 0.1Y, although, in principle, any alloy capable of forming an adherent aluminum oxide layer during oxidation can be used. A specimen is polished and oxidized to produce a thin, uniform insulating layer on one surface. Three platinum electrodes are sputtered on the oxide surface and the specimen is reoxidized.

Evidence for a Blood Ganglion Barrier in the Superior Cervical Ganglion of the Rat

1982 ◽  
Vol 40 ◽  
pp. 204-204
Author(s):  
D. M. DePace
Keyword(s):  
Blood Vessels ◽  
Superior Cervical Ganglion ◽  
Peripheral Nerves ◽  
Time Schedule ◽  
Transmission Electron ◽  
Cervical Ganglion ◽  
The Central Nervous System ◽  
Cervical Ganglia ◽  
Capillary Circulation ◽  
And Control

The majority of blood vessels in the superior cervical ganglion possess a continuous endothelium with tight junctions. These same features have been associated with the blood brain barrier of the central nervous system and peripheral nerves. These vessels may perform a barrier function between the capillary circulation and the superior cervical ganglion. The permeability of the blood vessels in the superior cervical ganglion of the rat was tested by intravenous injection of horseradish peroxidase (HRP). Three experimental groups of four animals each were given intravenous HRP (Sigma Type II) in a dosage of.08 to.15 mg/gm body weight in.5 ml of.85% saline. The animals were sacrificed at five, ten or 15 minutes following administration of the tracer. Superior cervical ganglia were quickly removed and fixed by immersion in 2.5% glutaraldehyde in Sorenson's.1M phosphate buffer, pH 7.4. Three control animals received,5ml of saline without HRP. These were sacrificed on the same time schedule. Tissues from experimental and control animals were reacted for peroxidase activity and then processed for routine transmission electron microscopy.

Effects of renovascular hypertension on rat adrenal zona glomerulosa

1978 ◽  
Vol 36 (2) ◽  
pp. 582-583
Author(s):  
G. Mazzocchi ◽  
P. Rebuffat ◽  
C. Robba ◽  
P. Vassanelli ◽  
G. G. Nussdorfer
Keyword(s):  
Renovascular Hypertension ◽  
Left Kidney ◽  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Zona Glomerulosa ◽  
Ultrastructural Changes ◽  
Albino Rats ◽  
Left Renal Artery ◽  
Angiotensin System ◽  
And Control

It is well known that the rat adrenal zona glomerulosa steroidogenic activity is controlled by the renin-angiotensin system. The ultrastructural changes in the rat zona glomerulosa cells induced by renovascular hypertension were described previously, but as far as we are aware no correlated biochemical and morphometric investigations were performed.Twenty adult male albino rats were divided into 2 experimental groups. One group was subjected to restriction of blood flow to the left kidney by the application of a silver clip about the left renal artery. The other group was sham-operated and served as a control. Renovascular hypertension developed in about 10 days: sistolic blood pressure averaged 165 ± 6. 4 mmHg, whereas it was about 110 ± 3. 8 mmHg in the control animals. The hypertensive and control rats were sacrificed 20 days after the operation. The blood was collected and plasma renin activity was determined by radioimmunological methods. The aldosterone concentration was radioimmunologically assayed both in the plasma and in the homogenate of the left capsular adrenal gland.

X-Ray Replication of Submicrometer Linewidth Patterns

1977 ◽  
Vol 35 ◽  
pp. 136-137
Author(s):  
Henry I. Smith ◽  
D.C. Flanders
Keyword(s):  
Electron Beam Lithography ◽  
Cross Sectional ◽  
X Ray ◽  
Electron Backscattering ◽  
Spatial Frequencies ◽  
Cross Sectional Profile ◽  
Carbon Foils ◽  
Sectional Profile ◽  
And Control ◽  
Soft Radiation

Scanning electron beam lithography has been used for a number of years to write submicrometer linewidth patterns in radiation sensitive films (resist films) on substrates. On semi-infinite substrates, electron backscattering severely limits the exposure latitude and control of cross-sectional profile for patterns having fundamental spatial frequencies below about 4000 Å(l),Recently, STEM'S have been used to write patterns with linewidths below 100 Å. To avoid the detrimental effects of electron backscattering however, the substrates had to be carbon foils about 100 Å thick (2,3). X-ray lithography using the very soft radiation in the range 10 - 50 Å avoids the problem of backscattering and thus permits one to replicate on semi-infinite substrates patterns with linewidths of the order of 1000 Å and less, and in addition provides means for controlling cross-sectional profiles. X-radiation in the range 4-10 Å on the other hand is appropriate for replicating patterns in the linewidth range above about 3000 Å, and thus is most appropriate for microelectronic applications (4 - 6).

Ultrastructural changes in sciatic nerve tissue: Effects of passive maternal smoking

1983 ◽  
Vol 41 ◽  
pp. 650-651
Author(s):  
Amankwah K.S. ◽  
A.D. Weberg ◽  
R.C. Kaufmann
Keyword(s):  
Sciatic Nerve ◽  
Maternal Smoking ◽  
Ultrastructural Level ◽  
Uranyl Acetate ◽  
Nerve Tissue ◽  
Ultrastructural Changes ◽  
Cacodylate Buffer ◽  
And Control ◽  
Spontaneous Delivery

Previous research has revealed that passive (involuntary inhalation) tobacco smoking during gestation can have adverse effects upon the developing fetus. These prior investigations did not concentrate on changes in fetal morphology. This study was undertaken to delineate fetal neural abnormalities at the ultrastructural level in mice pups exposed in utero to passive maternal smoking.Pregnant study animals, housed in a special chamber, were subjected to cigarette smoke daily from conception until delivery. Blood tests for determination of carbon monoxide levels were run at 15-18 days gestation. Sciatic nerve tissue from experimental and control animals were obtained following spontaneous delivery and fixed in 2.5% gluteraldehyde in 0.1M cacodylate buffer pH 7.3. The samples were post-fixed in osmium ferrocyanide (1:1 mixture of 1.5% aqueous OSO4 and 2.5% K4 Fe(CN)6). Following dehydration, the tissues were infiltrated with and embedded in Spurr. Sections were stained with uranyl acetate and lead citrate.

A Superconducting Microscope

1971 ◽  
Vol 29 ◽  
pp. 10-11 ◽  
Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson
Keyword(s):  
Liquid Helium ◽  
Focal Length ◽  
Vacuum System ◽  
Objective Lens ◽  
Electrical Instability ◽  
Radiation Shields ◽  
And Control ◽  
Thermal Oscillations ◽  
Flux Pump

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.

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