Kinetics and mechanism of the oxidation of acetaldehyde by chromic acid in perchloric acid

Summary The oxidation of MeCHO by chromium(VI) has been studied in HClO₄ medium over a wide range of experimental conditions and has been found to obey the rate law;v=k[MeCHO][HCrO ₄ ^– ][H⁺]. The calculated H and-S values for the reaction are 30±2kJ mol^–1 and 171±7J mol^–1deg^–1, respectively. The mechanism is discussed in terms of carbon-hydrogen bond cleavage.     

Kinetics and mechanism of oxidation of methanol by acid bromate

The kinetics of oxidation of methanol by bromate ion in hydrochloric acid medium has been investigated. A mechanism consistent with the experimental observations is suggested.

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Relative reactivities of glycerophosphates towards permanganate in perchloric acid medium

Summary The reactivities of - and -glycerophosphates towards MnO ₄ ^– in HClO₄ medium have been examined. The reactions between glycerophosphates and MnO ₄ ^– are first order with respect to [glycerophosphate], [MnO ₄ ^– ] and [H⁺]. There is no evidence for cleavage of the C–O–P bond rather than the terminal –CH₂OH group being oxidized to the respective phosphoglyceraldehyde.     

Formation of CuCo Alloy From Their Oxide Mixtures Through Reduction by Low-Temperature Hydrogen Plasma

Plasma Chemistry and Plasma Processing - Experimental results of a new method of production of CuCo alloy of composition 95Cu–5Co from the reduction of the mixture of cupric oxide (CuO) and...     

Experimental study of copper leveling additives and their wafer and pattern-scale effect on copper planarization

The impact of Cu leveling additives on electrodeposited Cu topography and subsequent planarization behaviour was studied on both the pattern and wafer scales. The leveling agent significantly reduces as-deposited Cu topography, especially “mounding”. The reduction in topography results in a higher effective Cu removal rate during subsequent Cu planarization, both at the pattern and wafer scales. On the wafer scale, this effect is more evident for lower overburdens as the topography must be eliminated in a shorter total polish time. For Cu electrodeposited from leveler additive-free chemistries, significant pattern-scale topography persists throughout almost the entire planarization process, whereas for Cu deposited using a leveling agent only very wide features (～ > 100 μm) show any significant topography evolution during Cu polish. It is shown that excess electrodeposited Cu topography can lead to poor in-plane Cu wiring leakage performance.     

Assessment of inhalation exposure potential of broken uranium ore piles in low-grade uranium mine

This paper presents the assessment of inhalation exposure potential of broken uranium ore piles in different stopes of Jaduguda uranium mines of India. ²²²Rn emanation coefficient of broken uranium ore was measured in laboratory by collecting air sample from airtight glass jar containing ore sample. An attempt was also made to correlate the emanation coefficient with ²²⁶Ra content of the ore. The ²²²Rn progeny doses estimated based on radon activity concentration of broken ore, occupancy period and equilibrium ratio in different stopes were well below the prescribed limit of International Commission on Radiological Protection. The maximum ²²²Rn progeny dose contribution from broken ore piles was worked out to be 0.22 mSv year^?1. This suggests that the broken ore piles are not the significant contributor of inhalation exposure under the existing ventilation condition of Jaduguda uranium mine.     

Kinetics of oxidation of hypophosphite ion by Au(III) in hydrochloric acid medium

Hypophosphite ion is oxidised by Au(III) in aqueous hydrochloric acid to give phosphorus acid and Au(I). The kinetics of the reaction has been studied spectrophotometrically in the UV region at different temperatures. The oxidation of hypophosphorous acid is first order with respect to both Au(III) and substrate. Hydrogen ion has no effect on the rate in acid media (0.15–1.0)M. The energy and entropy of activations are 128 ± 3.0kJ mol^?1 and 135.8 ± 6.5 JK^?1 mol^?1 respectively. The results are interpreted in terms of the probable formation of intermediate Au(lI).     

The role of the liquid interface agent in mechanical properties improvement of modified chalk filled polyolefins

On the basis of the experimental results described in detail in the following sections an explanation of the mechanism of liquid modifier in chalk filled PP action was proposed. After concluding that liquid modifier does not change the sample morphology and crystallinity it was stated that it facilitates filler particles translocation in polymer matrix during deformation. Such translocations are the necessary condition for saturation of volume increase of the sample due to void formation in the process of polymer filler separation preserving the sample from its premature fracture. The most important physicochemical parameter of liquid modifier seems to be its molecular weight. This parameter determines liquids ability to migrate in micropore structure arising under stress and thus to act as a cracking agent. The possibility of the importance of more efficient heat dissipation in the sample was shown indicating the role of better thermal contacts in the sample in the case of modified chalk used as a filler. Such picture of mechanism of liquid modifier action leads also to two important conclusions:

Due to polymer filler separation by means of liquid layer no further filler particles surface processing, as in some cases, is needed.

The method of modification can be easily generalized for other polymers especially other polyolefins [19], [20] as physicochemical requirements for liquid are known.

     

Parameśvara's rule for the circumradius of a cyclic quadrilateral

The expression for the circumradius of a cyclic quadrilateral in terms of its sides, usually attributed to L'Huilier in 1782, was known in India to Parame?vara (circa 1430). The present paper contains the original Sanskrit text of the rule, its English translation, and a discussion of its derivation as given by Sankara Váriar in his Kriy$\text{a}$kramakar$\text{i}$ (16th Century) along with relevant historical remarks.