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The weeds are becoming a major challenge for cotton production across the world, and the crop is infested by broad leaves, grasses, and sedges. Although the presence of weeds is deleterious for potential yield, the extent of losses depends on weed type, density, duration, and crop growth stage. Some weeds like Datura stramonium L., Amaranthus palmeri L., Amaranthus retroflexus L., and Ambrosia trifida L. cause significant yield losses at very low densities in comparison with Cucumis melo L. and Eleusine indica L. The cotton crop is very sensitive at early growth stages where weed presence during the first 2 months of growth may reduce yield from 10% to 90%. The most common effects of weeds on cotton quality are higher trash contents and lint staining problem. The various weed control options have been used for weed management in cotton; however, the efficacy of weed control methods remains low, probably by practicing weed control out of the critical period of weed-crop competition and selection of inappropriate method. The cost of weed control ranges from 54.5 to 320.6 US$ ha−1 in various cotton-growing countries of the world. The use of herbicides for weed control is common in the world; however, excessive and non-judicious use of herbicides led to the evolution of resistant weed biotypes. It provided the basis for development of glyphosate-tolerant cotton genotypes. The big change has been made for weed management with the advent of genetically modified glyphosate-tolerant cotton. It offers flexibility in herbicide use and time of application and improves weed control efficiency and economic returns. The evolution of herbicide resistance has been reported in Amaranthus palmeri L., Commelina benghalensis L., Conyza bonariensis L., Conyza canadensis L., and Sorghum halepense L. Some new technologies like Roundup Ready Xtend cotton and Enlist technology are being developed to cope to the challenge of glyphosate resistance.

Novel membranes were fabricated with woven Kevlar fabric sandwiched between two isotactic polypropylene layers and with various concentrations of adipic acid as the nucleating agent (NA). A thermally induced phase-separation dip-coating method was adopted to generate and control the microporosity in the developed membranes. Scanning electron microscopy and atomic force microscopy were used to directly observe and confirm the morphologies and micropores in the fabricated membranes. We observed that with an increase in the concentration of the NA in the fabricated membranes, both the pore density and pore size decreased. The average pore sizes were observed to be 1.686, 0.925, 0.372 μm, respectively, for 0.3, 0.5, and 0.7 pphr concentrations of the NA, respectively. The flux characteristics of the prepared membranes were also tested at various pressures with water, methanol, ethanol, and isopropyl alcohol as solvents in a custom-made filtration cell. The results obtained indicate the dependence of the flux on the type of solvent, pressure, and membrane. The flux for the solvents was observed to decrease with increasing concentrations of NA in the prepared membranes and was attributed to the decrease in the pore density and pore size. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2821–2831, 2013

Pristine multiwalled carbon nanotubes (MWCNTs) along with the silane coupling agent were incorporated into ethylene propylene diene monomer (EPDM) rubber using dispersion kneader and two roller mixing mill to fabricate ablative nanocomposites used in hyperthermal environment encountered by space vehicle or rocket motor. The 1 wt% addition of MWCNTS in the rubber matrix has remarkably reduced the backface temperature elevation up to 40°C during the ablation testing of the ablatives. The linear and mass ablation resistances have been diminished up to 125% and 74%, respectively, while insulation indexes at 110°C backface temperature of the composite specimens have been elevated up to 51% with increasing the MWCNTS incorporation into the EPDM matrix. Thermal stability and heat absorbance capability of the polymer composites were progressed with increasing the filler to matrix ratio. Thermal conductivity/impedance of the ablatives have been conducted according to the ASTM E1225-99 and D5470-03, respectively to execute the effect of MWCNTs concentration on the thermal transport characteristics of the tested specimens. Tensile strength of the composite specimen was augmented up to 42% with increasing nanotubes to polymer ratio. Evenly dispersed MWCNTs in the polymer matrix, polymer pyrolysis, and voids formation in the ablated samples can be scrutinized in the scanning electron microscopy images. POLYM. ENG. SCI., 54:255–263, 2014. © 2013 Society of Plastics Engineers

To enhance the ablation performance and mechanical strength of silicone rubber (SR), pristine multiwalled carbon nanotubes (MWNTs) were dispersed in the polymer matrix using dispersion kneader and two roller mixing mill. Electrical resistivity (100–300°C) was reduced with increasing filler concentration in the host matrix due to the presence and even dispersion of the nanofiller in the rubber matrix. The SR nanocomposite (1 wt % filler contents) has 28% better thermal stability and 100% improvement in the ultimate tensile strength is achieved as compared with the pristine polymer matrix counterpart. Oxy-acetylene torch was used to evaluate the ablation rates, % char yield, and backface temperature evolution at the back facet of nanoablators during the flame exposure for a specific duration. Ablation performance of the fabricated ablative nanocomposites was enhanced with increasing nanotubes concentration in the polymer matrix. Thermal stability and heat quenching ability of the SR nanocomposites were gradually augmented with increasing filler loadings in the host matrix. Porous silica char, polymer pyrolysis, char composition, and uniform dispersion of MWNTs in the rubber matrix were also analyzed using scanning electron microscopy and energy dispersive spectroscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The incorporation of silane treated multiwalled carbon nanotubes (S-MWCNTs) is used as an effective path for tailoring thermomechanical properties of ethylene propylene diene monomer (EPDM). In this study, S-MWCNTs were introduced into EPDM using internal dispersion kneader and two roller mixing mill. By altering the mass ratio of S-MWCNTs from 0 to 1, thermal conductivity, thermal stability and phase transition temperatures and their respective enthalpies are discussed of the fabricated nanocomposites. It is observed that silane modification improves their dispersion and increases the interfacial bonding between MWCNTs and polymer matrix. Scanning electron microscopy along energy dispersive spectroscopy analysis is performed to confirm the silane functionalized MWCNTs are selectively distributed in the host polymer. More importantly, an important increase in mechanical properties like ultimate tensile strength and hardness is achieved through introducing silane functionalized MWCNTs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43221.

Phenylethylidenehydrazine (PEH), a proposed metabolite of phenelzine (PLZ), was synthesized in our laboratories and administered to rats in a series of time- and dose–response studies. Phenelzine is a monoamine oxidase (MAO) inhibiting antidepressant/antipanic drug that also causes marked elevations of brain levels of the inhibitory neurotransmitter (γ-aminobutyric acid (GABA). Like PLZ, PEH inhibited GABA transaminase (GABA-T) and caused marked, long-lasting increases in rat brain levels of GABA. The addition of the double bond in PEH caused a marked decrease in its ability to inhibit MAO compared to PLZ. Given the ability of PEH to elevate GABA levels and its lack of significant effect on MAO, it may be a very effective and safe tool with which to study the role of GABA in anxiety disorders and may be a potentially useful compound to test against seizures, ischemia, mania, and stroke. Drug Dev. Res. 54:35–39, 2001. © 2001 Wiley-Liss, Inc.

A group of isopropyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-phenylpyridine-5-carboxylates (13–15) possessing ortho-, meta-, and para-CH2S(O)nMe and –S(O)nMe (n = 0–2) phenyl substituents were synthesized using a modified Hantzsch reaction. Calcium channel (CC) modulating activities were determined using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) in vitro assays. This class of –CH2S(O)nMe and –S(O)nMe (n = 0–2) compounds (13–15a–f) exhibited weaker CC antagonist activity on GPILSM (IC50 = > 1.1 × 10–5 to 4.1 × 10–6 M range) than the reference drug nifedipine (IC50 = 1.4 × 10–8 M). The oxidation state of the sulfur atom was a determinant of smooth muscle CC antagonist activity where the relative activity profile was generally thio (13, -CH2SMe, -SMe) and sulfonyl (15, -CH2SO2Me, -SO2Me) > sulfinyl (14, -CH2SOMe, -SOMe). The point of attachment of the phenyl substituent was a determinant of activity for the –CH2SMe (13a–c), -CH2SOMe (14a–c) and SOMe (14d–f) isomers where the relative potency order was meta and para > ortho. Compounds in this group (13–15), unlike Bay K 8644 (EC50 = 2.3 × 10–7 M on GPILSM), did not exhibit an agonist effect on GPILSM. The meta-CH2SMe (13b), ortho-CH2SMe (13c), meta-SMe (13e), and ortho-CH2SO2Me (15c) C-4 phenyl derivatives exhibited respectable in vitro cardiac positive inotropic activities (EC50 = 1.00 × 10–6 to 7.57 × 10–6 M range) relative to the reference drug Bay K 8644 (EC50 = 7.70 × 10–7 M) in the GPLA assay. In contrast to Bay K 8644, which acts as an undesirable calcium channel agonist on smooth muscle (GPILSM), compounds 13b (IC50 = 4.11 × 10–6 M), 13c (IC50 = 2.29 × 10–5 M), 13e (IC50 = > 1.20 × 10–5 M) and 15c (IC50 = 6.22 × 10–6 M) exhibited a desirable simultaneous calcium channel antagonist effect on smooth muscle at a similar (13b, 15c), or lower (13c, 13e), concentration relative to its cardiac agonist EC50 value. Model compounds such as 13b, 13c, 13e, and 15c, that exhibit dual cardioselective agonist / smooth muscle selective antagonist activities, represent a novel type of 1,4-dihydropyridine CC modulators that offer a potential approach to drug discovery targeted toward the treatment of congestive heart failure and for use as probes to study the structure–function relationship of calcium channels. Drug Dev. Res. 51:177–186, 2000. © 2001 Wiley-Liss, Inc.

A group of methyl 1,4-dihydro-2,6-dimethyl-4-(2-, 3- or 4-NHOH; 3- or 4-N=O)-phenyl-5-pyridinecarboxylates possessing a C-3 CO2Me or NO2 substituent [compounds 5–8, 10–12, below] were synthesized by reduction of the C-4 nitrophenyl precursors [1–4] to the corresponding phenylhydroxylamine [5–8] derivatives using 5% rhodium-on-charcoal with hydrazine hydrate as the hydrogen donor, followed by re-oxidation of the phenylhydroxylamine product [6–8] to the corresponding nitrosophenyl [10–12] derivative using pyridinium chlorochromate. A series of 1,4-dihydro-2,6-dimethyl-4-(2-trifluoromethylphenyl)pyridines [26–34] possessing CO2Me, COMe, CONH2, P(=O)OEt2, CN, NO2 C-3/C-5 substituents were synthesized using a modified Hantzsch reaction involving the condensation of 2-trifluoromethylbenzaldehyde [17] with an aminocrotonate [18–20] and a ketone [21–25] derivative. In vitro calcium channel (CC) activities were determined using a muscarinic-receptor-mediated Ca+2-dependent contraction of guinea pig ileal longitudinal smooth muscle assay. This class of compounds [5–8, 10–12, 26–34] exhibited weak CC antagonist activity [10–4 to 10–7 M range] relative to the reference drug nifedipine [IC50 = 1.4 × 10–8 M]. Structure–activity relationships [SARs] acquired were in agreement with known SARs where the relative potency order for C-4 phenyl substituents is ortho and meta > para. A C-3 nitro substituent decreased CC antagonist activity. Compounds 29–34 possessing C-3 CN or NO2, and a C-5 CO2Me, NO2, CONH2, COMe, or P(=O)OEt2, substituents exhibited weak CC antagonist activity in the 10–4 to 10–5 M range. Although this group of highly functionalized 1,4-dihydropyridines are not useful CC antagonists, they will serve as valuable model compounds to study the structure–function relationships of CC modulation. Drug Dev. Res. 42:120–130, 1997. © 1997 Wiley-Liss, Inc.

In this article, we report the effect of various carbon nanoparticle concentrations on the structural, curing, tan δ, viscosity variation during vulcanization, thermal, and mechanical characteristics of ethylene–propylene–diene monomer polymer sponge composites. The purpose of this study was to develop high-strength, foamy-structure polymer composites with an optimum filler to matrix ratio for advanced engineering applications. We observed that the structural, vulcanization, viscoelastic, and mechanical properties of the fabricated composites were efficiently influenced with the progressive addition of carbon content in the rubber matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39423.

Variant concentrations of ceramic fibers (CerFs) were incorporated into acrylonitrile butadiene rubber (NBR) to fabricate elastomeric ablative composites for ultrahigh temperature applications. The CerFs introduction into the polymer matrix has enhanced the ablation resistance up to 59% and successfully reduced the backface temperature of the polymer composite up to 110oC during the ultrahigh temperature ablation investigation. Thermal decomposition of the polymer composites was diminished up to 10% with increasing fiber concentration in the rubber matrix. Thermal conductivity was reduced equal to 63% while thermal impedance was enhanced up to 84% with the utmost fiber incorporation into the NBR matrix. The CerFs have adversely affected the mechanical properties of NBR matrix due to their brittle/inert nature and weak interface bonding with the host matrix. Scanning electron microscopy along with the energy dispersive x-ray spectroscopy was used to examine the ablated specimens and the fiber dispersion within the host matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4392–4400, 2013

The Hantzsch condensation of 2-azidoethyl acetoacetate with 2,3-dichlorobenzaldehyde and isopropyl 3-aminocrotonate afforded 3-(2-azidoethyl) 5-isopropyl 2,6-dimethyl-1,4-dihydro-4-(2,3-dichlorophenyl)pyridine-3,5-dicarboxylate (7). Reduction of the 3-(2-azidoethyl) moiety of 7 using 5% palladium-on-calcium carbonate and hydrogen gas gave the 3-(2-aminoethyl) derivative 8, which was subjected to guanylation using 1H-pyrazole-1-carboxamidine hydrochloride to yield the target 3-(2-guanidinoethyl) analog 9. The 3-(2-aminoethyl) product 8 was elaborated to the title compound 3-[2-(S-methylisothioureidoethyl)] 5-isopropyl 2,6-dimethyl-1,4-dihydro-4-(2,3-dichlorophenyl)pyridine-3,5-dicarboxylate hydrochloride (12) via the intermediate 3-(2-thioureidoethyl) compound 10. The 3-(2-guanidinoethyl 9 and 3-[2-(S-methylisothioureidoethyl)] 12 compounds were about 116- and 23-fold less potent calcium channel antagonists, respectively relative to the reference drug nifedipine.

A group of racemic alkyl 1,4-dihydro-2,6-dmethyl-4-(pyridinyl or 2-trifluoromethylphenyl)-5-(1H-tetrazol-5-yl)-3-pyridinecarboxylates 11-14 were prepared using the Hantzsch reaction that involved the condensation of 2-, 3- or 4-pyridinecarboxaldehyde, or 2-trifluoromethylbenzaldehyde, 8a-d with isopropyl or methyl 3-aminocrotonate (9a-b) and (5-(2-oxopropyl)-1H-tetrazole (10a) or 5-(2-oxopropyl)-1-methyl-1H-tetrazole (10b). In vitro calcium channel (CC) antagonist and agonist activities were determined using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) assays, respectively. In the series of compounds 11-14, only compounds 14a and 14b exhibited some weak CC antagonist activity (10 -6 M range) relative to the reference drug nifedipine (IC 50 =1.43x10 -8 M). Compounds 11b-14b having a 1-methyl-1H-tetrazol-5-yl substituent were inactive CC agonists on GPLA. In contrast, compounds 12a-14a having a 1H-tetrazol-5-yl substituent exhibited CC agonist activity on GPLA, but the C-4 2-pyridinyl analog 11a exhibited a mild negative inotropic effect. The approximately equipotent CC agonist activity (GPLA) exhibited by the C-4 pyridinyl 13a and 4-(2-tri-fluoromethylphenyl) 14a compounds compared favorably with that of the reference drug (±) Bay K 8644 (EC 50 =7.7x10 -7 M) indicating that the 1H-tetrazol-5-yl moiety is a suitable replacement for the nitro group present in Bay K 8644 with respect to cardiac CC agonist activity. These latter compounds 13a and 14a should serve as useful probes to study the structure-function relationships of calcium channels

5H-Indolo[3,2-a]-6H-phenothiazin-6-one and its regioisomer 1H-Indolo[2,3-a]-6H-phenothiazin-6-one were prepared by the condensation of 2-aminobenzenethiol with carbazole-1, 4-dione or with isomeric mixture of bromo-carbazole-1,4-diones.

A group of racemic alkyl 1,4-dihydro-2,6-dmethyl-4-(pyridinyl or 2-trifluoromethylphenyl)-5-(1H-tetrazol-5-yl)-3-pyridinecarboxylates 11-14 were prepared using the Hantzsch reaction that involved the condensation of 2-, 3- or 4-pyridinecarboxaldehyde, or 2-trifluoromethylbenzaldehyde, 8a-d with isopropyl or methyl 3-aminocrotonate (9a-b) and (5-(2-oxopropyl)-1H-tetrazole (10a) or 5-(2-oxopropyl)-1-methyl-1H-tetrazole (10b). In vitro calcium channel (CC) antagonist and agonist activities were determined using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) assays, respectively. In the series of compounds 11-14, only compounds 14a and 14b exhibited some weak CC antagonist activity (10 -6 M range) relative to the reference drug nifedipine (IC 50 =1.43x10 -8 M). Compounds 11b-14b having a 1-methyl-1H-tetrazol-5-yl substituent were inactive CC agonists on GPLA. In contrast, compounds 12a-14a having a 1H-tetrazol-5-yl substituent exhibited CC agonist activity on GPLA, but the C-4 2-pyridinyl analog 11a exhibited a mild negative inotropic effect. The approximately equipotent CC agonist activity (GPLA) exhibited by the C-4 pyridinyl 13a and 4-(2-tri-fluoromethylphenyl) 14a compounds compared favorably with that of the reference drug (±) Bay K 8644 (EC 50 =7.7x10 -7 M) indicating that the 1H-tetrazol-5-yl moiety is a suitable replacement for the nitro group present in Bay K 8644 with respect to cardiac CC agonist activity. These latter compounds 13a and 14a should serve as useful probes to study the structure-function relationships of calcium channels

A group of racemic 3-[2-nitrooxyethyl (1,3-dinitrooxy-2-propyl or 4-nitrophenylethyl)] 5-isopropyl 1,4-dihydro-2,6-dimethyl-4-[2-trifluoromethylphenyl (2-nitrophenyl or 3-nitrophenyl)]-3,5-pyridinedicarboxylates 13-15 were prepared using the Hantzsch reaction that involved the condensation of 2-nitrooxyethyl 9a, 1,3-dinitrooxy-2-propyl 9b or 4-nitrophenylethyl 9c acetoacetate with isopropyl 3-aminocrotonate 11 and 2-trifluoromethyl 12a, 2-nitro 12b or 3-nitro 12c benzaldehyde. In vitro calcium channel antagonist activities were determined using a guinea pig ileum longitudinal smooth muscle assay. Compounds 13-15 exhibited superior, or equipotent, calcium channel antagonist activity (10 -8 to 10 -10 M range) relative to the reference drug nifedipine (IC 50 = 1.43 x 10 -8 M). The R 1 C-3 ester substituent was a determinant of calcium channel antagonist activity where the potency order was CH 2 CH 2 ONO 2 > CH 2 CH 2 -C 6 H 4 -4-NO 2 ≥ CH(CH 2 ONO 2 ) 2 . In contrast, the C-4 R 2 -aryl substituent (2-CF 3 -C 6 H 4 -, 2-O 2 N-C 6 H 4 -or 3-O 2 N-C 6 H 4 -) was not a major determinant of activity. Compounds 13a-15a which possess a 3-(2-nitrooxyethyl) ester substituent exhibit superior calcium channel antagonist smooth muscle relaxant activity (IC 50 = 10 -10 M range) relative to nifedipine, could serve as potential probes to investigate the in vivo release of nitric oxide (NO) which induces vascular muscle relaxation.

Synthese de la dihydro-2',3' cholestano-5α [5,6,7-bc] [1',5'] benzothiazepine et de ses derives acetoxy-3β et chloro-3β a partir de cholestene-5ones-7 et de l'amino-2benzenethiol