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Preservation of foods with ionising radiations
VACUUM Classified A b s t r a c t s
I --
General
Science
and
Engineering
--
I
Contd.
each o t h e r a solid precipitate w a s o b t a i n e d . A f t e r r e m o v a l of tile residual m o n o m e r b y freezing a n d v a c u u m s u b l i m a t i o n tile p r e c i p i t a t e w a s q u a l i t a t i v e l y f r a c t i o n a t e d into t h r e e c o m p o n e n t s : (a) Consisting e s s e n t i a l l y of poly acrylonitrile, (b) t h e block polymer, r e p r e s e n t i n g a b o u t one t h i r d of t h e t o t a l a n d c o n t a i n i n g 75 % acrylonitrile, (c) t h e u s u a l d e g r a d a t i o n p r o d u c t of poly m e t h y l v i n y l ketone. T h e e x p e r i m e n t s a p p e a r to confirm t h a t p h o t o l y s i s of poly m e t h y l v i n y l k e t o n e in t h e presence of acrylonitrile is i n s t i u m e n t a l in t h e s y n t h e t i c p r o d u c tion of t w o f u r t h e r p o l y m e r i c s p e c i e s - - p u r e poly acrylonitrile a n d a block p o l y m e r of b o t h materials. Sommaire : O n a t r o u v 6 que la p h o t o l y s e du ' p o l y m e t h y l v i n y l k e t o n e ' en presence d'acrylonitrile c o n d u i t ~ la p r o d u c t i o n de d e u x n o u v e a u x genres de polym6rique.
The Combination of Methyl Radicals: Photolysis of Acetone at Low P r e s s u r e s
O
Canada. T h e m e c h a n i s m w h e r e b y m e t h y l radicals, p r i m a r i l y p r o d u c e d b y t h e d e c o m p o s i t i o n of a c e t o n e e x p o s e d to u l t r a - v i o l e t radiation, c o m b i n e to f o r m e t h a n e h a s b e e n i n v e s t i g a t e d before, d o w n to a c e t o n e p r e s s u r e s of 20 ram. Hg. T h e p r e s e n t i n v e s t i g a t i o n e x t e n d s this s t u d y d o w n to a p r e s s u r e level of 0.2 m m . Hg. T h e r e s u l t s o b t a i n e d c o n f i r m tile p r e v i o u s l y p o s t u l a t e d t h i r d b o d y r e q u i r e m e n t s for e t h a n e f o r m a t i o n , a c e t o n e itself a c t i n g as t h i r d b o d y . T h e e x p e r i m e n t a l reaction vessel was a q u a r t z cylinder 100 cm. long a n d 3.9 cm. in d i a m e t e r . H e a t i n s u l a t i o n was p r o v i d e d b y w r a p p i n g tile cylinder w i t h a l u m i n i u m foil a n d P y r e x t a p e a n d t h e u n i f o r m i t y of t h e t e m p e r a t u r e w i t h i n t h e cylinder was 32 1 ° over its whole l e n g t h a t 250°C. H e a t w a s supplied b y r e s i s t a n c e h e a t i n g . T b e r a d i a t i o n w a s o b t a i n e d f r o m a B . T . H . M E / D 250 W . d.c. q u a r t z w i n d o w l a m p w h i c h gives s t r o n g e m i s s i o n a t 3,130, %660, 3,906 a n d 4,047 A. To facilitate q u a n t u m yield m e a s u r e m e n t s t h e line 3,130 ~_ e m i t t e d b y t h e l a m p w a s isolated. L i g h t a b s o r p t i o n w a s m e a s u r e d b y m e a n s of a G L 935 photo-cell. N o r m a l l y 5 % c o n v e r s i o n of t h e a c e t o n e w a s r e g a r d e d as sufficient. All m a t e r i a l s u s e d in t h e reaction, i.e. r e a g e n t - g r a d e acetone, a c e t a l d e h y d e , benzene, perfluoromethylcyclohexane, p e r f l u o r o b u t a n e a n d c a r b o n dioxide, t h e latter few r e p r e s e n t i n g a d d e d gases, were purified b y distillation a n d o u t g a s s e d prior to use. Separa t i o n a n d a n a l y s i s of t h e r e a c t i o n p r o d u c t s w a s carried o u t b y k n o w n m e t h o d s a n d w a s checked w i t h t h e aid of a m a s s s p e c t r o m e t e r . E t h a n e w a s s e p a r a t e d o u t in a liquid n i t r o g e n t r a p (-210°C). R e s u l t s for v a r i o u s acetone p r e s s u r e s are g i v e n in g r a p h s . A d d i n g t h e gases m e n t i o n e d above increased t h e relative rate of e t h a n e formati(m. Sommaire : E t u d e du m d c a n i s m e de f o r m a t i o n d ' 6 t h a n e k p a r t i r de r a d i c a u x de m e t h y l p r o d u i t s p a r la p h o t o l y s e d ' a c d t o n e h basses pressions.
The Electron Microscopy of Photographic Grains.
Specimen Preparation Techniques and Applications
Abstract No. and References
Artide by J. E. Guillet & R. G. W. Norrish Nature x73 , 3.4.1954 625-627 183/1
Article bv R. E. Dodd & E. W. R. Steaeie Proe. Roy. Soe. 223A, May 1954 283-295 184/I
See A b s t r a c t N o . : l l l / I I
Evacuating Photographic Materials for Use in Electron Optical Apparatus
185/:
See A b s t r a c t No. : l l 0 / I I
O
An! reproved Replica Technique for Electron Microscopy of Paint Films United States. F o r t h e s t u d y of organic films, s u c h as films of soft p a i n t s , it is e s s e n t i a l to e m p l o y replica t e c h n i q u e s w h i c h exclude t h e risk of e x p o s i n g t h e film surface to h i g h t e m p e r a t u r e s . T h e a u t h o r s f o u n d t h a t t h e silver-silica replication t e c h n i q u e i n v o l v e s s u c h a risk a n d r e p o r t on a successful modification of t h a t t e c h n i q u e b y s u b s t i t u t i n g P V A (Elvanol, g r a d e 51-05) for silver for t h e n e g a t i v e replicas. Care h a s to be t a k e n t h a t tile n e g a t i v e is t h i n e n o u g h to o b t a i n a h i g h resolution a n d dissolves w i t h o u t i n j u r y to t h e silica. T h e P V A film is p r o d u c e d b y flooding t h e s p e c i m e n surface, d r a i n i n g off t h e excess a n d d r y i n g in a vertical position of t h e s p e c i m e n for 8 - 1 6 hours. L o n g e r d r y i n g periods result in brittleness. T h e P V A replica strips r e a d i l y f r o m p a i n t film applied to t i n p l a t e and, while f a s t e n e d to a m e t a l holder w i t h a d h e s i v e tape, is coated w i t h silica b y v a c u u m e v a p o r a t i o n . I t is desirable to prolong p u m p i n g at 10 -4 ram. H g u p to 16 h o u r s to e l i m i n a t e all t r a c e s of a b s o r b e d water. 0.8 rag. to 1.4 nag. of silica are e v a p o r a t e d , t h e t h i c k n e s s of t h e silica layer d e p e n d i n g on tile r o u g h n e s s of t h e surface. T h e finished c o m p o s i t e f i h n s are c u t into o n e - e i g h t h i n c h s q u a r e s a n d placed, silica-side up, in distilled water, w h e n t h e P V A dissolves a w a y quickly. T h e silica replicas are t h e n w a s h e d before t r a n s f e r to t h e s p e c i m e n grids. S h a d o w i n g of t h e replicas w i t h c h r o m i u m is r e c o m m e n d e d . T h e n e w m e t h o d h a s been used for t h e s t u d y of t h e u n d e r s i d e of e n a m e l films. E x a m p l e s of t h e a p p l i c a t i o n of t h e t e c h n i q n e s to gloss e n a m e l s a n d l a c q u e r s are g i v e n in illustrations. T h e n e w m e t h o d indicates p i g m e n t d i s t r i b u t i o n a n d related defects m o s t satisfactorily b u t finer details s u c h as molecular c o n f i g u r a t i o n a n d s m a l l d i s t o r t i o n s of t h e p a i n t vehicle are b e t t e r s h o w n b y silver-silica replicas. Sommaire : l)escription d ' u n e t e c h n i q u e de r6plique double, modifi66, p o u r r e m p l a c e r la t e c h n i q u e de rdplique a u silicate d ' a r g e n t d a n s la r6plique de surfaces molles de couche de p e i n t u r e .
186/I
Article by A. S. Powcll L. R. LeBras E. G. Bobalek, & W. Von Fischer J. Appl. Phys. 25, June 1954 757-760
The Electron Microscope with Particular Reference to Its Use in Biological Research. I See A b s t r a c t No. : 108/1I
181/i
Preservation of Foods with Ionising Radiations
i88/I
United Kingdom. A r e p o r t is g i v e n of a s h o r t s y m p o s i u m held a t C a m b r i d g e in F e b r u a r y 1954 on t h e a b o v e subject. T h e powerful sources of ionising r a d i a t i o n s t h a t h a v e r e c e n t l y b e c o m e available o p e n u p possibilities J u l y , 1954
Vacuum Vol I V No 3
366
VACUUM Classified A b s t r a c t s
I --
General
Science
and
Engineering
--
Abstrac~ No. and References
I
Co.td.
O
of preserving food b y killing the o r g a n i s m s tllat cause spoilage. Doses of 2-5 × 10 a r.e.p, have been found to break the r e p r o d u c t i o n cycle of insects in foods (e.g. trichina larvae) and l - S x 10 n r.e.p, are needed to inactivate virus. M a n y foods develop 'radiation' o d o u r s which m a y render t h e m unsuitable for h u m a n c o n s u m p t i o n . This effect can be minimised b y reducing the dose level to 2 × l04 r.e.p, which is still useful for disinfestation. O t h e r m e a s u r e s are de-aeration, deep freezing, and, as an alternative to the latter, the addition of ascorbic acid. E a c h foodstuff h a s to be considered separately. Vegetables and fruit contain enzymes which are active during storage and are n o t n o r m a l l y inactivated b y irradiation. The m o s t serious biological effect of irradiation is a loss of the p r o p e r t y of cell reproduction. Tissue cells s h o w s y m p t o m s indicating t u m o u r development. These adverse effects are a t t r i b u t e d to the f o r m a t i o n of free radicals in the presence of water. This aspect of irradiation effects requires f u r t h e r clarification. Available radiation sources are electrical generators supplying high speed electrons and radioactive sources p r o d u c i n g b e t a or g a m m a rays. I n the former class are \ r a n de Graaft accelerators and travelling wave linear accelerators. W i t h an electron b e a m p o w e r of 4 kXV already obtainable from such generators material a b o u t 1 inch thick, if radiated f r o m b o t h sides, could be sterilised at a rate of a b o u t 1,000 lb. per h o u r at a cost of a few pence per lb. B u t as electrons have a c o m p a r a t i v e l y low p e n e t r a t i o n the use of g a m m a r a y s m a y be preferable. These can be obtained either from s p e n t reactor fuel rods during the cooling period or alternatively from fission p r o d u c t s which remain after chemical processing of t h e fuel rods. A m e d i u m sized, nuclear p o w e r s t a t i o n could sterilise a b o u t 1,000 t o n s per d a y f r o m its s p e n t fuel rods alone. The use of fission p r o d u c t s has the a d v a n t a g e t h a t the radiation sources would be t r a n s p o r t a b l e and it is expected t h a t the cost will be a b o u t the same as in the case of sterilisation b y electrical generators. Sommaire: R a p p o r t sur u n s y m p o s i u m de st~rilisation de p r o d u i t s alimentaires au m o y e n de radiations ionisantes.
Conference Report by R. S. Hannan Nature x73, 24.4.1954 752-754
189/i
Physical Instability and Thermal Shock in Red Cells See A b s t r a c t No. : l l 8 / I I
A Freeze Drying Apparatus for Neurohistochemical Work United Kb,gdom. A freeze d r y i n g a p p a r a t u s is described which employs no diffusion p m n p s or auxiliary heaters and is capable of d r y i n g s i m u l t a n e o u s l y several g r o u p s of brain tissue in the form of slices for histochemical s t u d y of e n z y m e location.
(Authors) Sommaire : Description d ' u n appareil k lyophiliser sans p o m p e s k diffusion ou chauffages auxiliaires, capable de lyophiliser s i m u l t a n ~ m e n t plusieurs g r a m m e s de tissues de cerveau, sous forme de tranches, p o u r localiser les e n z y m e s d u r a n t l'6tude histochimique.
190/1
Letter by
D. Naido & O. E. Pratt Vacuu?n
4, April 1954 195-197
191/I
Lyophilisation of Poliomyelitis Virus, Heat Inactivation of Dry MEFi Virus See A b s t r a c t No. : 5 0 / I V
O
Mechanical Production of Expiratory Flow Rates Surpassing the Capacity of H u m a n Coughing United States. Various a p p a r a t u s which produce an artificial cough in p a t i e n t s suffering f r o m complaints which cause bronchial secretions and o t h e r i m p e d i m e n t s to n o r m a l r e s p i r a t o r y functions (i.e. poliomyelitis, bronchial
192/1
a s t h m a , etc.) are already k n o w n b u t none of these designs e m p l o y s negative pressure which would increase its effectiveness. Details are given of a new a p p a r a t u s of this kind called E . W . N . P . (Exsufflation W i t h Negative
Peak Expiratory Flow Rates During a Cough of Maximal Effort and During E . I V . N . P . ~a88
No.
Diagnosis
Cough
CC./88C.
E.IF.N.P. ce./see.
E.W.N.P.×IO0 Cough per cent.
I 1.
2. 3. 4. 5.
1. 2.
3. 4. 5.
July, 1954
A. NORMAL SUBJECTS 5380 7820 8360 9040 5380 7820 10670 9040 4570 6200
145 108 145 b5 136
B. PATIENTS WITH BRONCHIAL ASTHMA, PULMONARY EMPHYSEMA AND BRONCHIECTASIS Pulmonary Emphysema 3000 7280 243 Pulmonary Emphysema 3000 8910 297 Bronchiectasis 7820 9450 121 Pulmonary emphysema and 3000 6200 207 Bronchial asthma i Pulmonary emphysema 5790 8230 142
Vacuum Vol, I V No. 3
367
I --
General
Science
and
Engineering
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I
Contd.
each o t h e r a solid precipitate w a s o b t a i n e d . A f t e r r e m o v a l of tile residual m o n o m e r b y freezing a n d v a c u u m s u b l i m a t i o n tile p r e c i p i t a t e w a s q u a l i t a t i v e l y f r a c t i o n a t e d into t h r e e c o m p o n e n t s : (a) Consisting e s s e n t i a l l y of poly acrylonitrile, (b) t h e block polymer, r e p r e s e n t i n g a b o u t one t h i r d of t h e t o t a l a n d c o n t a i n i n g 75 % acrylonitrile, (c) t h e u s u a l d e g r a d a t i o n p r o d u c t of poly m e t h y l v i n y l ketone. T h e e x p e r i m e n t s a p p e a r to confirm t h a t p h o t o l y s i s of poly m e t h y l v i n y l k e t o n e in t h e presence of acrylonitrile is i n s t i u m e n t a l in t h e s y n t h e t i c p r o d u c tion of t w o f u r t h e r p o l y m e r i c s p e c i e s - - p u r e poly acrylonitrile a n d a block p o l y m e r of b o t h materials. Sommaire : O n a t r o u v 6 que la p h o t o l y s e du ' p o l y m e t h y l v i n y l k e t o n e ' en presence d'acrylonitrile c o n d u i t ~ la p r o d u c t i o n de d e u x n o u v e a u x genres de polym6rique.
The Combination of Methyl Radicals: Photolysis of Acetone at Low P r e s s u r e s
O
Canada. T h e m e c h a n i s m w h e r e b y m e t h y l radicals, p r i m a r i l y p r o d u c e d b y t h e d e c o m p o s i t i o n of a c e t o n e e x p o s e d to u l t r a - v i o l e t radiation, c o m b i n e to f o r m e t h a n e h a s b e e n i n v e s t i g a t e d before, d o w n to a c e t o n e p r e s s u r e s of 20 ram. Hg. T h e p r e s e n t i n v e s t i g a t i o n e x t e n d s this s t u d y d o w n to a p r e s s u r e level of 0.2 m m . Hg. T h e r e s u l t s o b t a i n e d c o n f i r m tile p r e v i o u s l y p o s t u l a t e d t h i r d b o d y r e q u i r e m e n t s for e t h a n e f o r m a t i o n , a c e t o n e itself a c t i n g as t h i r d b o d y . T h e e x p e r i m e n t a l reaction vessel was a q u a r t z cylinder 100 cm. long a n d 3.9 cm. in d i a m e t e r . H e a t i n s u l a t i o n was p r o v i d e d b y w r a p p i n g tile cylinder w i t h a l u m i n i u m foil a n d P y r e x t a p e a n d t h e u n i f o r m i t y of t h e t e m p e r a t u r e w i t h i n t h e cylinder was 32 1 ° over its whole l e n g t h a t 250°C. H e a t w a s supplied b y r e s i s t a n c e h e a t i n g . T b e r a d i a t i o n w a s o b t a i n e d f r o m a B . T . H . M E / D 250 W . d.c. q u a r t z w i n d o w l a m p w h i c h gives s t r o n g e m i s s i o n a t 3,130, %660, 3,906 a n d 4,047 A. To facilitate q u a n t u m yield m e a s u r e m e n t s t h e line 3,130 ~_ e m i t t e d b y t h e l a m p w a s isolated. L i g h t a b s o r p t i o n w a s m e a s u r e d b y m e a n s of a G L 935 photo-cell. N o r m a l l y 5 % c o n v e r s i o n of t h e a c e t o n e w a s r e g a r d e d as sufficient. All m a t e r i a l s u s e d in t h e reaction, i.e. r e a g e n t - g r a d e acetone, a c e t a l d e h y d e , benzene, perfluoromethylcyclohexane, p e r f l u o r o b u t a n e a n d c a r b o n dioxide, t h e latter few r e p r e s e n t i n g a d d e d gases, were purified b y distillation a n d o u t g a s s e d prior to use. Separa t i o n a n d a n a l y s i s of t h e r e a c t i o n p r o d u c t s w a s carried o u t b y k n o w n m e t h o d s a n d w a s checked w i t h t h e aid of a m a s s s p e c t r o m e t e r . E t h a n e w a s s e p a r a t e d o u t in a liquid n i t r o g e n t r a p (-210°C). R e s u l t s for v a r i o u s acetone p r e s s u r e s are g i v e n in g r a p h s . A d d i n g t h e gases m e n t i o n e d above increased t h e relative rate of e t h a n e formati(m. Sommaire : E t u d e du m d c a n i s m e de f o r m a t i o n d ' 6 t h a n e k p a r t i r de r a d i c a u x de m e t h y l p r o d u i t s p a r la p h o t o l y s e d ' a c d t o n e h basses pressions.
The Electron Microscopy of Photographic Grains.
Specimen Preparation Techniques and Applications
Abstract No. and References
Artide by J. E. Guillet & R. G. W. Norrish Nature x73 , 3.4.1954 625-627 183/1
Article bv R. E. Dodd & E. W. R. Steaeie Proe. Roy. Soe. 223A, May 1954 283-295 184/I
See A b s t r a c t N o . : l l l / I I
Evacuating Photographic Materials for Use in Electron Optical Apparatus
185/:
See A b s t r a c t No. : l l 0 / I I
O
An! reproved Replica Technique for Electron Microscopy of Paint Films United States. F o r t h e s t u d y of organic films, s u c h as films of soft p a i n t s , it is e s s e n t i a l to e m p l o y replica t e c h n i q u e s w h i c h exclude t h e risk of e x p o s i n g t h e film surface to h i g h t e m p e r a t u r e s . T h e a u t h o r s f o u n d t h a t t h e silver-silica replication t e c h n i q u e i n v o l v e s s u c h a risk a n d r e p o r t on a successful modification of t h a t t e c h n i q u e b y s u b s t i t u t i n g P V A (Elvanol, g r a d e 51-05) for silver for t h e n e g a t i v e replicas. Care h a s to be t a k e n t h a t tile n e g a t i v e is t h i n e n o u g h to o b t a i n a h i g h resolution a n d dissolves w i t h o u t i n j u r y to t h e silica. T h e P V A film is p r o d u c e d b y flooding t h e s p e c i m e n surface, d r a i n i n g off t h e excess a n d d r y i n g in a vertical position of t h e s p e c i m e n for 8 - 1 6 hours. L o n g e r d r y i n g periods result in brittleness. T h e P V A replica strips r e a d i l y f r o m p a i n t film applied to t i n p l a t e and, while f a s t e n e d to a m e t a l holder w i t h a d h e s i v e tape, is coated w i t h silica b y v a c u u m e v a p o r a t i o n . I t is desirable to prolong p u m p i n g at 10 -4 ram. H g u p to 16 h o u r s to e l i m i n a t e all t r a c e s of a b s o r b e d water. 0.8 rag. to 1.4 nag. of silica are e v a p o r a t e d , t h e t h i c k n e s s of t h e silica layer d e p e n d i n g on tile r o u g h n e s s of t h e surface. T h e finished c o m p o s i t e f i h n s are c u t into o n e - e i g h t h i n c h s q u a r e s a n d placed, silica-side up, in distilled water, w h e n t h e P V A dissolves a w a y quickly. T h e silica replicas are t h e n w a s h e d before t r a n s f e r to t h e s p e c i m e n grids. S h a d o w i n g of t h e replicas w i t h c h r o m i u m is r e c o m m e n d e d . T h e n e w m e t h o d h a s been used for t h e s t u d y of t h e u n d e r s i d e of e n a m e l films. E x a m p l e s of t h e a p p l i c a t i o n of t h e t e c h n i q n e s to gloss e n a m e l s a n d l a c q u e r s are g i v e n in illustrations. T h e n e w m e t h o d indicates p i g m e n t d i s t r i b u t i o n a n d related defects m o s t satisfactorily b u t finer details s u c h as molecular c o n f i g u r a t i o n a n d s m a l l d i s t o r t i o n s of t h e p a i n t vehicle are b e t t e r s h o w n b y silver-silica replicas. Sommaire : l)escription d ' u n e t e c h n i q u e de r6plique double, modifi66, p o u r r e m p l a c e r la t e c h n i q u e de rdplique a u silicate d ' a r g e n t d a n s la r6plique de surfaces molles de couche de p e i n t u r e .
186/I
Article by A. S. Powcll L. R. LeBras E. G. Bobalek, & W. Von Fischer J. Appl. Phys. 25, June 1954 757-760
The Electron Microscope with Particular Reference to Its Use in Biological Research. I See A b s t r a c t No. : 108/1I
181/i
Preservation of Foods with Ionising Radiations
i88/I
United Kingdom. A r e p o r t is g i v e n of a s h o r t s y m p o s i u m held a t C a m b r i d g e in F e b r u a r y 1954 on t h e a b o v e subject. T h e powerful sources of ionising r a d i a t i o n s t h a t h a v e r e c e n t l y b e c o m e available o p e n u p possibilities J u l y , 1954
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VACUUM Classified A b s t r a c t s
I --
General
Science
and
Engineering
--
Abstrac~ No. and References
I
Co.td.
O
of preserving food b y killing the o r g a n i s m s tllat cause spoilage. Doses of 2-5 × 10 a r.e.p, have been found to break the r e p r o d u c t i o n cycle of insects in foods (e.g. trichina larvae) and l - S x 10 n r.e.p, are needed to inactivate virus. M a n y foods develop 'radiation' o d o u r s which m a y render t h e m unsuitable for h u m a n c o n s u m p t i o n . This effect can be minimised b y reducing the dose level to 2 × l04 r.e.p, which is still useful for disinfestation. O t h e r m e a s u r e s are de-aeration, deep freezing, and, as an alternative to the latter, the addition of ascorbic acid. E a c h foodstuff h a s to be considered separately. Vegetables and fruit contain enzymes which are active during storage and are n o t n o r m a l l y inactivated b y irradiation. The m o s t serious biological effect of irradiation is a loss of the p r o p e r t y of cell reproduction. Tissue cells s h o w s y m p t o m s indicating t u m o u r development. These adverse effects are a t t r i b u t e d to the f o r m a t i o n of free radicals in the presence of water. This aspect of irradiation effects requires f u r t h e r clarification. Available radiation sources are electrical generators supplying high speed electrons and radioactive sources p r o d u c i n g b e t a or g a m m a rays. I n the former class are \ r a n de Graaft accelerators and travelling wave linear accelerators. W i t h an electron b e a m p o w e r of 4 kXV already obtainable from such generators material a b o u t 1 inch thick, if radiated f r o m b o t h sides, could be sterilised at a rate of a b o u t 1,000 lb. per h o u r at a cost of a few pence per lb. B u t as electrons have a c o m p a r a t i v e l y low p e n e t r a t i o n the use of g a m m a r a y s m a y be preferable. These can be obtained either from s p e n t reactor fuel rods during the cooling period or alternatively from fission p r o d u c t s which remain after chemical processing of t h e fuel rods. A m e d i u m sized, nuclear p o w e r s t a t i o n could sterilise a b o u t 1,000 t o n s per d a y f r o m its s p e n t fuel rods alone. The use of fission p r o d u c t s has the a d v a n t a g e t h a t the radiation sources would be t r a n s p o r t a b l e and it is expected t h a t the cost will be a b o u t the same as in the case of sterilisation b y electrical generators. Sommaire: R a p p o r t sur u n s y m p o s i u m de st~rilisation de p r o d u i t s alimentaires au m o y e n de radiations ionisantes.
Conference Report by R. S. Hannan Nature x73, 24.4.1954 752-754
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Physical Instability and Thermal Shock in Red Cells See A b s t r a c t No. : l l 8 / I I
A Freeze Drying Apparatus for Neurohistochemical Work United Kb,gdom. A freeze d r y i n g a p p a r a t u s is described which employs no diffusion p m n p s or auxiliary heaters and is capable of d r y i n g s i m u l t a n e o u s l y several g r o u p s of brain tissue in the form of slices for histochemical s t u d y of e n z y m e location.
(Authors) Sommaire : Description d ' u n appareil k lyophiliser sans p o m p e s k diffusion ou chauffages auxiliaires, capable de lyophiliser s i m u l t a n ~ m e n t plusieurs g r a m m e s de tissues de cerveau, sous forme de tranches, p o u r localiser les e n z y m e s d u r a n t l'6tude histochimique.
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Letter by
D. Naido & O. E. Pratt Vacuu?n
4, April 1954 195-197
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Lyophilisation of Poliomyelitis Virus, Heat Inactivation of Dry MEFi Virus See A b s t r a c t No. : 5 0 / I V
O
Mechanical Production of Expiratory Flow Rates Surpassing the Capacity of H u m a n Coughing United States. Various a p p a r a t u s which produce an artificial cough in p a t i e n t s suffering f r o m complaints which cause bronchial secretions and o t h e r i m p e d i m e n t s to n o r m a l r e s p i r a t o r y functions (i.e. poliomyelitis, bronchial
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a s t h m a , etc.) are already k n o w n b u t none of these designs e m p l o y s negative pressure which would increase its effectiveness. Details are given of a new a p p a r a t u s of this kind called E . W . N . P . (Exsufflation W i t h Negative
Peak Expiratory Flow Rates During a Cough of Maximal Effort and During E . I V . N . P . ~a88
No.
Diagnosis
Cough
CC./88C.
E.IF.N.P. ce./see.
E.W.N.P.×IO0 Cough per cent.
I 1.
2. 3. 4. 5.
1. 2.
3. 4. 5.
July, 1954
A. NORMAL SUBJECTS 5380 7820 8360 9040 5380 7820 10670 9040 4570 6200
145 108 145 b5 136
B. PATIENTS WITH BRONCHIAL ASTHMA, PULMONARY EMPHYSEMA AND BRONCHIECTASIS Pulmonary Emphysema 3000 7280 243 Pulmonary Emphysema 3000 8910 297 Bronchiectasis 7820 9450 121 Pulmonary emphysema and 3000 6200 207 Bronchial asthma i Pulmonary emphysema 5790 8230 142
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