EPA error risked halving India's rice harvest

Methane has attracted particular attention as a greenhouse gas, as once it is formed, mitigation strategies are not easy to devise. The US Environmental Protection Agency (EPA) estimated in 1990 that global methane emission is about 550 Tg (550 million tonnes) per annum, with about 110 Tg of this released from paddy cultivation. This estimate turned out to be wrong, but it could have had devastating consequences for the economy of India

Unusual effect of tellurium doping on the electrical-properties of bulk amorphous selenium

Abstract is not available

Double glass transition phenomena and fractional crystallization in Ge20Te80−Ge_{20}Te_{80}- and Al23Te77−Al_{23}Te_{77}- glasses

The phenomena of double glass transition and the double stage crystallization were observed for bulk $Ge_{20}Te_{80}$ [54742-42-6] and $Al_{23}Te_{77}$ [67676-86-2] glasses. The structural details at each stage of crystallization were examined by x-ray and electron diffraction. The pressure induced crystallization of these alloys was studied

Critical resistivity in impurity doped binary liquid mixtures

The electrical resistance of the critical binary liquid system C6H12+(CH3CO)2O is measured both in the pure form and when the system is doped with small amounts (≈ 100 ppm) of H2O impurities. Near Tc, the resistance varies as dR/dT = A1+A2 (T-Tc)-b with b ≈ 0.35. Neither the critical exponent b nor the amplitude ratio A1/A2 are affected by the impurities. A sign reversal of dR/dT is noticed at high temperatures T much greater-than Tc

Effects of capillary waves on the thickness of wetting layers

The free energy contribution of capillary waves is calculated to show its significant dependence on the thickness of the liquid layer, when the thickness is very small. It is shown that these oscillations can play an important role in determining the thermodynamic stability of a wetting layer, close to the critical point of a binary liquid mixture in the case of both short range and long range forces. In particular, the thickness of the wetting layer goes to zero as the temperature T approaches Tc

Heat-Capacity Measurements - Progress In Experimental-Techniques

The heat capacity of a substance is related to the structure and constitution of the material and its measurement is a standard technique of physical investigation. In this review, the classical methods are first analyzed briefly and their recent extensions are summarized. The merits and demerits of these methods are pointed out. The newer techniques such as the a.c. method, the relaxation method, the pulse methods, the laser flash calorimetry and other methods developed to extend the heat capacity measurements to newer classes of materials and to extreme conditions of sample geometry, pressure and temperature are comprehensively reviewed. Examples of recent work and details of the experimental systems are provided for each method. The introduction of automation in control systems for the monitoring of the experiments and for data processing is also discussed. Two hundred and eight references and 18 figures are used to illustrate the various techniques

Physical ultrasonics: Current scenario and future prospects

Physical ultrasonics is a mature field and in this review some branches of the subject are discussed. After a brief introduction, various ultrasonic transducers like piezoelectric, ceramic, capacitive, electromagnetic and optical methods for generation of ultrasonic waves have been discussed. Some linear and non-linear ultrasonic phenomena are then summarized. In the case of non-linear phenomena, parametric arrays, acoustic cavitation, sonoluminescence and sonochemistry have been presented. A discussion of surface acoustic waves and devices, optical storage cell, acoustooptic effects and underwater acoustics is then given. Finally some special topics such as, acoustic emission, acoustic microscopy, sound amplification by stimulated emission of radiation, medical diagnosis and ultrasonic lithotripsy are discussed briefl

Average lattices and aperiodic structures

Statistically averaged lattices provide a common basis to understand the diffraction properties of structures displaying deviations from regular crystal structures. An average lattice is defined and examples are given in one and two dimensions along with their diffraction patterns. The absence of periodicity in reciprocal space corresponding to aperiodic structures is shown to arise out of different projected spacings that are irrationally related, when the grid points are projected along the chosen coordinate axes. It is shown that the projected length scales are important factors which determine the existence or absence of observable periodicity in the diffraction pattern more than the sequence of arrangement