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561. Vacuum technical problems in the food industry
Classified Abstracts
33.
General Physics
and Electronics 33
550. An optically
large-field emission microscope for thermionic research. (Great Britain). A. Sandor, J. Electron & Control, 13 (3), Sept. 1962, 231-247.
33 551. Limitations to resolving power in the thermique emission microscope. (Great Britain). A. Sandor, J. Electron & Control, 13 (4), Oct. 1962, 295-304.
552. Electron instrumentation
microscopy of and techniques.
K. D. Carroll, Div.
Lockhead
LMSD/895033,
metallic surfaces. (U.S.A.).
Aircraft
June
A
Corp.-Missiles
survey
33 of
1960. 33
oscillations have been obtained during the recombination period following a pulsed radio frequency or d.c. discharge in helium mixed with either neon or carbon dioxide at wavelengths of 1 .153r and 1.069~ respectively. The optimum gas pressure for the neon mixtures were 1 torr and 7 x 1O-2 torr respectively and slightly higher for the carbon The authors concluded that dioxide (2 torr and 8 x 1OW torr). the oscillations are produced by a dissociative mechanism and not by direct electron excitation. H. A. H. Boot and D. M. Clume, Nature, 197 (4863), 12 Jan. 173-174.
33 554. Suppression of emission from portions of barium-activated tungsten dispenser cathodes and adjoining electrodes. R. Levi and E. S. Rittner, Proc. Inst. Radio Engrs., 49, Aug. 1961, 1323.
555. Electron trigonometry-a design. U.S.A. Electron trigonometry
new
tool
for
33 : 56 electron-optical
is a new method, to predict image formation in an electron-optical system, which may consist of one, or more, electron lenses of finite length, including electrostatic, magnetic, or mixed lenses. It provides immediate information about the size and position of an electron image, without resort to ray tracing or the determination of cardinal points. (Author, modified) K. Schlesinger, Proc. Inst. Radio Engr., 49, Oct. 1961, 1538-1549. 33 556. Quantitative electron microscopy-a review. (U.S.A.). E. Zeitler and G. F. Bahr, R.C.A. Sci. Znstrum. News, 7 (2), Aug. 1962, 3-l I. 33 for protecting oxide-coated cathodes. and P. Zieske, Rev. Sci. Znstrum., 33 (lo),
557. Vacuum-lock M. J. Kofoid 1962, 1115.
558. Simple gauge for obtaining preselected the electron microscope. (U.S.A.). C. B. Reimer, Rev. Sci. Instrum.,
magnifications
Oct.
33 with
33 (lo), Oct. 1962, 1126-1127. 33
559. Large ultra-high
vacuum
valve.
B. A. Caldwell and D. F. Klemperer, Dec. 1962, 1458.
(U.S.A.). Rev. Sci. Znstrum.,
beam evaporation
in high vacuum.
33 : 30 of vacuum deposited dielectric films.
Electron bombardment apparatus plant. See Abstr. No. 536.
33 : 30 for a high vacuum evaporation
33 : 22 : 37 The theory of a parasitic frequency dependent current in the See Abstr. No. 511. Redhead r.f. mass spectrometer. 33 : 22 : 37 The origin of parasitic meters
and methods
currents in high frequency mass spectroSee Abstr. No. 510. of suppression.
See Abstr.
Phenomena occurring long gaps in vacuum. Duoplasmatron
at electrically stressed See Abstr. No. 499.
as a vacuum
ultraviolet
metallic
light source.
33 : 18 : 56 surfaces in
See
33 : 18 Abstr.
No. 503. 33 : 19 Photo-luminescence and growth defects in ZnS : Cu monocrystals. See Abstr. No. 504.
36.
Drying, Degassing and Concentration 36
560. Vacuum W. Germany.
drying.
The theory on which vacuum drying is based is discussed by considering the various modes of heat transfer and movement of moisture in the matter to be dried. The present state of the art is illustrated by means of a number of typical examples. (in German) (Author, modified) F. Kneule, Vakuum-Tech&, 11 (4), May 1962, 115-121. 36 : 54 561. Vacuum technical problems in the food industry. (Germany). G. Nemitz, Vakuum-Tech&, 11 (6), Sept. 1962, 172-173. 36 : 54 562. Application
of vacuum in medicine
and the pharmaceutical
industry. France.
The article deals mainly with the problems underlying the freeze drying of delicate pharmaceutical products. The freezing of pure water is first discussed and the extraordinary differences in size and shape of ice crystals depending on rate of cooling and lowest temperature reached are pointed out. In the case of solutions, matters are much more complicated due to the formation of eutectics. In many cases the physical state of such mixtures will depend on their thermal history and also on whether a certain state has been reached by heating or cooling the system. Matters can be clarified by taking continuous records of both temperature and electrical resistance of the solution during freezing and thawing. Such exploratory investigations should be carried out on any product before freeze drying is attempted. The author shows how such temperature and resistance records are also useful in controlling the drying process and give warning of any accidental lignefaction in the interior of the material. It is this difficulty of control which limits the freeze drying process at the moment to relatively thin sheets. There is also still some doubt whether the final product should be vacuum packed or sealed under an atmosphere of nitrogen. W. J. S. L. R. Rey, Le Vide, 17 (98), March/April
1962, 134-147.
33 (12),
33 Electron
Temperature characteristics See Abstr. No. 544.
and Space
553. Pulsed gaseous maser. Great Britain. Optical maser
1963,
207
550-563
: 30
No. 546.
36 : 54 563. General principles of the freeze-drying of food. France. The different steps in the freeze-drying process are The freezing period is examined and some freezing described.
33.
General Physics
and Electronics 33
550. An optically
large-field emission microscope for thermionic research. (Great Britain). A. Sandor, J. Electron & Control, 13 (3), Sept. 1962, 231-247.
33 551. Limitations to resolving power in the thermique emission microscope. (Great Britain). A. Sandor, J. Electron & Control, 13 (4), Oct. 1962, 295-304.
552. Electron instrumentation
microscopy of and techniques.
K. D. Carroll, Div.
Lockhead
LMSD/895033,
metallic surfaces. (U.S.A.).
Aircraft
June
A
Corp.-Missiles
survey
33 of
1960. 33
oscillations have been obtained during the recombination period following a pulsed radio frequency or d.c. discharge in helium mixed with either neon or carbon dioxide at wavelengths of 1 .153r and 1.069~ respectively. The optimum gas pressure for the neon mixtures were 1 torr and 7 x 1O-2 torr respectively and slightly higher for the carbon The authors concluded that dioxide (2 torr and 8 x 1OW torr). the oscillations are produced by a dissociative mechanism and not by direct electron excitation. H. A. H. Boot and D. M. Clume, Nature, 197 (4863), 12 Jan. 173-174.
33 554. Suppression of emission from portions of barium-activated tungsten dispenser cathodes and adjoining electrodes. R. Levi and E. S. Rittner, Proc. Inst. Radio Engrs., 49, Aug. 1961, 1323.
555. Electron trigonometry-a design. U.S.A. Electron trigonometry
new
tool
for
33 : 56 electron-optical
is a new method, to predict image formation in an electron-optical system, which may consist of one, or more, electron lenses of finite length, including electrostatic, magnetic, or mixed lenses. It provides immediate information about the size and position of an electron image, without resort to ray tracing or the determination of cardinal points. (Author, modified) K. Schlesinger, Proc. Inst. Radio Engr., 49, Oct. 1961, 1538-1549. 33 556. Quantitative electron microscopy-a review. (U.S.A.). E. Zeitler and G. F. Bahr, R.C.A. Sci. Znstrum. News, 7 (2), Aug. 1962, 3-l I. 33 for protecting oxide-coated cathodes. and P. Zieske, Rev. Sci. Znstrum., 33 (lo),
557. Vacuum-lock M. J. Kofoid 1962, 1115.
558. Simple gauge for obtaining preselected the electron microscope. (U.S.A.). C. B. Reimer, Rev. Sci. Instrum.,
magnifications
Oct.
33 with
33 (lo), Oct. 1962, 1126-1127. 33
559. Large ultra-high
vacuum
valve.
B. A. Caldwell and D. F. Klemperer, Dec. 1962, 1458.
(U.S.A.). Rev. Sci. Znstrum.,
beam evaporation
in high vacuum.
33 : 30 of vacuum deposited dielectric films.
Electron bombardment apparatus plant. See Abstr. No. 536.
33 : 30 for a high vacuum evaporation
33 : 22 : 37 The theory of a parasitic frequency dependent current in the See Abstr. No. 511. Redhead r.f. mass spectrometer. 33 : 22 : 37 The origin of parasitic meters
and methods
currents in high frequency mass spectroSee Abstr. No. 510. of suppression.
See Abstr.
Phenomena occurring long gaps in vacuum. Duoplasmatron
at electrically stressed See Abstr. No. 499.
as a vacuum
ultraviolet
metallic
light source.
33 : 18 : 56 surfaces in
See
33 : 18 Abstr.
No. 503. 33 : 19 Photo-luminescence and growth defects in ZnS : Cu monocrystals. See Abstr. No. 504.
36.
Drying, Degassing and Concentration 36
560. Vacuum W. Germany.
drying.
The theory on which vacuum drying is based is discussed by considering the various modes of heat transfer and movement of moisture in the matter to be dried. The present state of the art is illustrated by means of a number of typical examples. (in German) (Author, modified) F. Kneule, Vakuum-Tech&, 11 (4), May 1962, 115-121. 36 : 54 561. Vacuum technical problems in the food industry. (Germany). G. Nemitz, Vakuum-Tech&, 11 (6), Sept. 1962, 172-173. 36 : 54 562. Application
of vacuum in medicine
and the pharmaceutical
industry. France.
The article deals mainly with the problems underlying the freeze drying of delicate pharmaceutical products. The freezing of pure water is first discussed and the extraordinary differences in size and shape of ice crystals depending on rate of cooling and lowest temperature reached are pointed out. In the case of solutions, matters are much more complicated due to the formation of eutectics. In many cases the physical state of such mixtures will depend on their thermal history and also on whether a certain state has been reached by heating or cooling the system. Matters can be clarified by taking continuous records of both temperature and electrical resistance of the solution during freezing and thawing. Such exploratory investigations should be carried out on any product before freeze drying is attempted. The author shows how such temperature and resistance records are also useful in controlling the drying process and give warning of any accidental lignefaction in the interior of the material. It is this difficulty of control which limits the freeze drying process at the moment to relatively thin sheets. There is also still some doubt whether the final product should be vacuum packed or sealed under an atmosphere of nitrogen. W. J. S. L. R. Rey, Le Vide, 17 (98), March/April
1962, 134-147.
33 (12),
33 Electron
Temperature characteristics See Abstr. No. 544.
and Space
553. Pulsed gaseous maser. Great Britain. Optical maser
1963,
207
550-563
: 30
No. 546.
36 : 54 563. General principles of the freeze-drying of food. France. The different steps in the freeze-drying process are The freezing period is examined and some freezing described.