Proximity effect on the general base catalysed hydrolysis of amide linkage: the role of cationic surfactant, CTABr

The bis phenoxide forms of (1,2)bis(2-hydroxybenzamido)ethane(I), (1,5)bis(2-hydroxybenzamido) 3-azapentane(II), (1,3)bis(2-hydroxybenzamido)propane(III), and (1,8)bis(2-hydroxybenzamido)3,6- diazaoctane(IV) undergo facile hydrolysis of one of the amide groups (0.02 ≤ [OH−]T (mol dm−3) ≤ 0.5, 10% MeOH (v/v) + H2O medium) without exhibiting [OH−] dependence. The reactivity trend follows I ~ II > > III ~ IV with low activation enthalpy {25.7±2.8 ≤ ΔH≠(kJ mol−1) ≤ 64.8 ± 7.0}. The high negative and comparable values of activation entropy{−234 ± 8 ≤ ΔSΔ (J K−1 mol−1) ≤ −127 ± 20} are consistent with closely similar, and ordered transition states which can be assembled by favourably oriented phenoxide groups. The solvent kinetic isotope effect for I, kH2O/kD2O+H2O ~ 1 (20 and 50 volume% D2O), indicates that proton transfer is not involved as a part of the rate controlling process. The observed slowing down of the rate of this reaction for I in the micellar pseudo phase of CTABr also supports the proposed mechanism. Under premicellar conditions, however, rate acceleration is observed, a consequence believed to be associated with the capping effect of the hydrophobic tail of the surfactant cation forming the reactive ion-pair, CTA+, (I-2H)2− exclusively in the aqueous pseudo phase

Foliar feeding of boron influencing biochemical attributes and enzyme activity in dragon fruit (Selenicereus monacanthus)

Boron plays crucial role in metabolic processes during fruit ripening and in turn ensures better fruit quality. However limited studies have been conducted to assess the influence of boron on fruit quality of dragon fruit. In the present study, the efficacy of boron was investigated on red-fleshed dragon fruit (Selenicereus monacanthus). Four levels of boron (100 mgL-1, 200 mgL-1, 300 mgL-1 and 400 mgL-1) were applied on 7- and 14-day-old flower buds. The highest pollen germinability, seed weight, fruit weight (274.32 ± 36.72g), pulp content (70.80 ± 1.79%) and pulp firmness (2.74 ± 0.18 N) were recorded when B was applied@300 mg L-1 on 7-day old flower bud. The same treatment also manifested higher soluble solid contents (17.42 ± 0.62 °Brix), sugar content, total carbohydrate (15.92 ± 1.12%), protein (1.33±0.11%), ascorbic acid (112.66 ± 4.98 µg/g), betacyanin (32.86±2.52 µg/g), total phenol (95.26 ± 3.72 µg GAE/ 100g), total flavonoid (37.65 ±2.14 mg QE/100g) and anti-oxidative activity (27.71±2.14 mM Fe II/100g). Correlation studies elucidated significant positive influence of pollen germinability on fruit weight, pulp content and pulp firmness. The activities of α-amylase, invertase and sucrose synthase enzymes were significantly upregulated with the application of B 300 mg L-1 on 7-day old flower bud. On the other hand, the activities of cell wall degrading enzymes such as cellulase, polygalacturonase and pectin methyl esterase were reduced with increasing levels of boron. The principal component analysis (PCA) illustrated the maximal proximity of most of the quality attributes with B 300 mgL-1, applied at 7-day old flower bud stage, thus exemplifying it as the best treatment

Performance of GCMs for seasonal prediction over India—a case study for 2009 monsoon

The 2009 drought in India was one of the major droughts that the country faced in the last 100 years. This study describes the anomalous features of 2009 summer monsoon and examines real-time seasonal predictions made using six general circulation models (GCMs). El Niño conditions evolved in the Pacific Ocean, and sea surface temperatures (SSTs) over the Indian Ocean were warmer than normal during monsoon 2009. The observed circulation patterns indicate a weaker monsoon in that year over India with weaker than normal convection over the Bay of Bengal and Indian landmass. Skill of the GCMs during hindcast period shows that neither these models simulate the observed interannual variability nor their multi-model ensemble (MME) significantly improves the skill of monsoon rainfall predictions. Except for one model used in this study, the real-time predictions with longer lead (2- and 1-month lead) made for the 2009 monsoon season did not provide any indication of a highly anomalous monsoon. However, with less lead time (zero lead), most of the models as well as the MME had provided predictions of below normal rainfall for that monsoon season. This study indicates that the models could not predict the 2009 drought over India due to the use of less warm SST anomalies over the Pacific in the longer lead runs. Hence, it is proposed that the uncertainties in SST predictions (the lower boundary condition) have to be represented in the model predictions of summer monsoon rainfall over India