Sealed Vacuum Tubes Research Articles

Growth of silica nanowires in vacuum

Silica nanowires were grown on a Pt-coated Si substrate in flowing Ar, dynamic vacuum, and sealed vacuum tubes.

Selective Synthesis of Magnetic Fe2P/C and FeP/C Core/Shell Nanocables

Composite core−shell nanostructures have greatly extended the properties of single-component counterparts, and display new bi- or multifunctionality in optical, electric, magnetic, catalytic, and biological performances. In this letter, we described the selective synthesis of uniform magnetic Fe2P/C and FeP/C core/shell nanocables via an organometallic route by thermolysis reactions of ferrocene (Fe(C5H5)2) with triphenylphosphine (PPh3) in sealed vacuum tubes at ∼400 °C. The selective synthesis was readily accessed by controlling the heating rate and the molar ratio of reactants, and the Fe2P/C and FeP/C nanocables exhibited interesting ferromagnetic−paramagnetic transition with high blocking temperatures. Our method enriches core species and carbon sources for carbon shells, which can be widely extended to prepare new types of inorganic/carbon core−shell nanostructures, and the resulting magnetic nanocables may be used as components in nanomagnetic devices.

A developed Ullmann reaction to III–V semiconductor nanocrystals in sealed vacuum tubes

Group III-V (13-15, III = Ga, In, and V = P, As) semiconductor nanocrystals were effectively obtained via a developed Ullmann reaction route through the reactions of preformed nanoscale metallic indium or commercial gallium with triphenylphosphine (PPh(3)) and triphenylarsine (AsPh(3)) in sealed vacuum quartz tubes under moderate conditions at 320-400 degrees C for 8-24 h. The developed synthetic strategy in sealed vacuum tubes extends the synthesis of III-V semiconductor materials, and the air-stable PPh(3) and AsPh(3) with low toxicity provide good alternative pnicogen precursors for the synthesis of III-V nanocrystals. The analysis of XRD, ED and HRTEM established the production of one-dimensional (1D) metastable wurtzite (W) InP, InAs and GaP nanostructures in the zinc blende (ZB) products. Further investigations showed that 1D W nanostructures resulted from kinetic effects under the moderate synthetic conditions employed and the steric effect of PPh(3) and AsPh(3), and that the tendency for the synthesis of III-V nanocrystals was in the orders of IIIP > IIIAs and GaV > InV on the basis of experiments and thermodynamic calculations. Meanwhile, the microstructures and growth mechanism of the III-V nanocrystals were investigated.

On the temporal development of erythrocyte sedimentation rate using sealed vacuum tubes

The temporal development of the erythrocyte sedimentation rate (ESR) was studied in wide, short vacuum tubes. It was found that in about 3% of the specimens arriving in the laboratory the ESR developed in three different phases during 60 min, whereas the other showed only two. The specimens with three phases behaved similarly in the Westergren method. It was shown that the Westergren ESR can be estimated with an acceptable accuracy already from measurements obtained after 30 min. Reproducibility and precision were improved by using a special instrument. Several advantages by this procedure were recognized, e.g., quicker results, identification of several otherwise missed rapid ESR. Accurate timing of the readings further improves accuracy and precision, and permits estimation of ESR (Westergren) up to 100 mm. In view of the obvious phases in the development of the ESR, it is proposed that this abbreviation is interpreted as erythrocyte sedimentation reaction and that the kind of quantity that is length is expressed in mm.

Attaining ultrahigh vacuum in sealed vacuum tubes by means of oil-free pumps with low pumping speed: S Fleischer et al, Exper Tech Phys, 18 (1–2), 1970, 69–74 ( in German)

Attaining ultrahigh vacuum in sealed vacuum tubes by means of oil-free pumps with low pumping speed: S Fleischer et al, Exper Tech Phys, 18 (1–2), 1970, 69–74 ( in German)

Properties and structure of glasses in the system AsS

In obtaining the glass, at first, the raw materials were mixed up and melted by using porcelain crucible, but in this case it was found by infra-red absorption method that the glass contains some oxygen impurities. Then a range of glasses was prepared by melting elementary pure As and S in definite proportions in a sealed vacuum tube. The infra-red absorption, molecular volume, molecular refraction, hardness, thermal expansion and viscosity of sample glasses with various compositions were investigated and, additionally, solubility of these glasses into CS 2 was measured. The structure of glasses in the system AsS was studied by X-ray diffraction and a structural model was set up. From the measurements the following conclusions were made. The structure of As 2S 3 glass is a distorted form of the crystalline orpiment structure. With increasing S content above As 2S 3, S is likely to exist in the chain-like form, but when the S content is greater than that in As 2S 8–10, both chain-like and ring type forms co-exist. With decreasing S content below As 2S 3, S between As and As is eliminated and AsAs bonds are formed. Consequently a deformation of layer occurs and an expansion of the layer distance was observed.

Replacement of arterial segments utilizing flexible orlon prostheses.

BEGINNING in 1944 and in the ensuing years we have been active in the investigation of the problems of arterial homografts. Early in this work we felt the need for some method for preserving such grafts for use at a time considerably after their removal. Initially, we advocated the use of rapidly frozen grafts and showed that such grafts could be kept for prolonged periods of time at temperatures of -70 C.* Later the rapid freezing process was supplemented by drying in the frozen state, 3 and after this we devised the method for the sterilization of such grafts with the use of ethylene oxide, both as a liquid and as a gas. 4 The culmination of this process has therefore been the use of freeze-dried grafts which can be kept indefinitely in sealed vacuum tubes after being taken without aseptic precautions. For the past two years all the homografts

Further Development in Supervoltage Therapy Apparatus

THIS paper is the continuation, and, to some extent, an enlargement, of a similar one presented elsewhere (7) on the same subject about two years ago. It deals in the first instance with the latest development of supervoltage roentgen therapy apparatus, but also considers briefly certain other medical possibilities of extremely high voltages. Whereas it may be said that the general principles of engineering design in the high voltage field have been laid down in a most satisfactory way from the beginning, during the past two years numerous technical detail developments have been added which make a review of the entire question of construction worth while. (A) Supervoltage Technic for the Production of Very Hard Roentgen Rays (Acceleration of Electrons) (a) Emitting Source (Tube Design) (1) Sealed Vacuum Tubes —The development of sealed vacuum tubes for increasingly higher voltages has long formed a most intriguing problem of engineering research. From the point of view of therapeutic application, such a t...