DFT calculations were carried out in order to study the second-order nonlinear optical (NLO) response of a series of proposed 2D polyoxometalate-based terpyridine-substituted compounds. These compounds can be formulated as [Mo 6 O 17 {N 4 C 25 H 16 (X) 2 }{N 4 C 25 H 16 (X) 2 }] 2-(X = H, F, Cl, Br, I, CF 3 , or CN), which has a wedge Λ-shaped acceptor--π-conjugated bridge--donor--π-conjugated bridge--acceptor (A-π-D-π-A) configuration. The calculations showed that these compounds possess significantly large molecular secondorder polarizabilities that range from approximately 1000 ϫ 10 -30 to 4300 ϫ 10 -30 esu. The combination of trifluoromethyl (CF 3 ) and cyanide (CN) groups at the end of the terpyridine ligand strengthens the bridge conjugation, which is useful for the enhancement of the NLO response.

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Field crops are subjected to numerous inconsiderate climatic hazards that negatively affect physiological processes, growth and yield. Drought is one of the major abiotic factors that limits the agricultural productivity especially in the arid and semi-arid areas of the globe. Silicon (Si) is a naturally occurring beneficial nutrient which modulates plant growth and development events and has been known to improve the crop tolerance to abiotic stresses. With the objective to investigate the role of silicon nutrition on maize hybrids under limited moisture supply, a two year field study was conducted during 2010-11 at Post Graduate Research Station (PARS), University of Agriculture Faisalabad, Pakistan. We evaluated growth of two maize hybrids P-33H25 and FH-810 under well watered (100% field capacity) and water deficit situation (60% field capacity) as affected by Si application. Silicon was added in soil @ 100 mg/kg using Calcium Silicate as source. Water deficit condition significantly reduced agro-morphological and physiological attributes of maize plants. Silicon application significantly increased the plant height, leaf area index, yield and related attributes along with improvement in photosynthetic rate, leaf water status and osmotic adjustment under limited moisture supply. It was concluded that silicon application to droughtstressed maize enhanced its growth and yield owing to improved photosynthetic rate, higher osmotic adjustment, increased water status and lowered transpiration.

W heat is a major grain crop and primary staple food of Pakistan and it is a major source of carbohydrates and energy (Chattha et al., 2017a(Chattha et al., , 2018. The seed of wheat contains 2.11% minerals, 68% carbohydrate, 2.9% fat, 15.4% proteins and an important source of calories and micro-nutrients Abstract | Delayed wheat sowing is the main factor responsible for the lower yield of wheat owing to low temperature during emergence and early growth. Seed size has an appreciable potential to improve stand establishment, growth, and yield under late sowing conditions. Therefore, the present study was performed to assess the impact of diverse seed sizes (SS) on the growth and yield of wheat crop under late sowing conditions. The study was comprised of different sowing dates (SD), SD 1 : 15 th December, SD 2 : and 30 th December and different seed size classes i.e. bold (having a diameter of > 2.7 mm), medium (having a diameter of > 2.3 mm to 2.7 mm), small (having a diameter of ≤ 2.3 mm) and mixed seeds. The results indicated that different sowing dates and seed size classes had a significant effect on germination, growth, and yield of wheat crop. The crop sown on 15 th December took less time to start emergence (7.8 days) and resulted in maximum plant height (81 cm), grains per spike (44.5), productive tillers (321.5), spike length (10.2 cm), 1000 grain weight (37.2 g), and grain yield (3.83 t ha -1 ) and maximum time to start emergence (11 days) and minimum plant height (60 cm), grains per spike (35.7), productive tillers (273), spike length (8.6 cm), 1000 grain weight (32 g), and grain yield (2.7 t ha -1 ) was recorded in the crop sown on 30 th December. In the case of seed size classes, bold seed performed appreciably well and took less time to start emergence (8.5 days) and had more plant height (74.7 cm), productive tillers (326), spike length (10.1 cm), grains per spike (45), 1000 grain weight (37 g), and grain yield (3.67 t ha -1 ) compared to other seed size classes. In conclusion, bold seed size can significantly improve the wheat production under late sown conditions due to better stand establishment, vigorous germination, and increase in yield related traits.

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This study involves elucidation of spatial and temporal influences on horizontal and vertical distribution and fate of contaminants of emerging concerns (CECs) in riverain systems. In total, 23 CECs encompassing antibiotics, nonantibiotic drugs, and bisphenol analogues were detected. The antibiotic concentrations were relatively higher in deep water than in surface water. Spatial connectivity and spatial autocorrelation suggested the occurrence and concentration of the majority of the CECs devoid of neighboring site influences, owing to shorter correlation lengths than the average distances between the sampling sites, hence indicating the localized distribution of CECs in surface water. The PCA biplot indicated that bisphenol A and methyl paraben were mainly responsible for the seasonal variations. Both negative and positive correlations existed between CECs and the environmental parameters to cause temporal variations in CEC contaminants. Spatial structure analysis by singular vector decomposition (SVD) analysis was used to measure the sitewise contribution of CECs. The results indicated relatively higher CEC contaminants and deteriorated water quality in the downstream sites rather than in the upstream sites. This study effectively demonstrated the use of different chemometric techniques for in-depth understanding of various spatial and temporal influences on the fate and horizontal and depth distribution of CECs in riverain systems.

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