Absolute negative resistance and multivaluedness on current-voltage characteristics of tunnel diodes

The effect of external perturbations of large amplitude in the form of a coherent signal or noise on the behavior of dynamic and static current-voltage (I–V) characteristics of tunnel diodes has been experimentally investigated. It is shown that, when an appropriate frequency is chosen, an increase in the amplitude of the external coherent signal leads to the occurrence of multivaluedness and absolute negative resistance on the I–V characteristics of tunnel diodes. The noise effect suppresses the N-type negative differential resistance on the I–V characteristics of tunnel diodes and significantly distorts these characteristics. A possible mechanism of the occurrence of absolute negative resistance is proposed.     

Recombination instability and double S-switching in <Emphasis Type="Italic">p</Emphasis>-Ge(Au)

We report on the experimental investigation of p-Ge(Au) samples and compare the results qualitatively to a one-dimensional theoretical model describing the recombination instability of current in gold-compensated germanium in a two-parameter (voltage-emission) space. Experiments showed the existence of three regimes of the system functioning in the parametric space. The second S-switching region was found on the current-voltage characteristic, which is probably related to a noise-induced nonequilibrium phase transition.     

Comments on “H2-optimal zeros”

It is shown that Theorem 2.1 from the above paper by Kubamba-Meerkov (1994) is the interpretation of the classical result on the Rayleigh quotient     

Updating of equipment for thermochemical treatment of steel parts in a fluidized bed

Results of updating commercial equipment for thermochemical treatment (TCT) of steel parts in a fluidized bed are presented. The updating has led to the creation of an ecologically safe treatment area with mechanized equipment for carburizing and carbonitriding in a fluidized bed with the use of natural gas, ammonia, and compressed air instead of the equipment for pack cyaniding.     

Method of determining the single-domain property of magnetic powder particles

A method of determining the single-domain property of magnetic powder particles based on Mossbauer spectroscopy is proposed and checked experimentally. Pis’ma Zh. Tekh. Fiz. 23, 70–3 (December 26, 1997)     

Deoxyribonuclease treatment improves the homogeneity of single-stranded DNA preparations

The isolation of single-stranded (ss) phagemid DNA using standard protocols often results in impure preparations, which contain undesirable quantities of chromosomal and/or double-stranded (ds) phagemid DNA. Here we report a simple and efficient method for elimination of virtually all dsDNA by incubation of phagemid viral particles with deoxyribonuclease I. In addition to analyzing the ratio of linear-to-circular topological forms of ssDNA after deoxyribonuclease I treatment, we verified that no decrease in transformation efficiency occurred and demonstrated that ssDNA molecules covered by capsid proteins remained intact following such treatment.     

Convective mass exchange between flows in a valve-pulsatory apparatus with permeable partition

A mathematical model of convective mass exchange between flows in a valve-pulsatory apparatus with permeable partition is proposed. The mass exchange between flows of aqueous Na₂CO₃ solution and distilled water, or pearlite suspension in water and aqueous solution of NaCl was studied on a pilot apparatus.     

Specific heat and magnetocaloric effect of Pr1−x Ag x MnO3 manganites

This paper presents experimental results of the specific heat and magnetocaloric effect in Pr_1?x Ag _x MnO₃ (x = 0.05–0.25) manganites. A maximum value of magnetic entropy change for the sample with x = 0.15 was observed in magnetic field of 18 kOe at T _C = 125 K and was ΔS _max ≈ 2.96 J/kg K. In Pr_0.95Ag_0.05MnO₃ sample, a sign inversion of the magnetocaloric effect was observed at low temperatures (~80 K) in low magnetic fields of 750 Oe. The coexistence of ferromagnetic and canted antiferromagnetic phases with closely spaced critical temperatures was found to force the magnetocaloric effect into abrupt sign inversion.