24 research outputs found
Extensive study of the electron donor 1,1,4,4-tetrathiabutadiene (TTB) and of its charge transfer crystal with TCNQ
No full textIn the spirit of the renewed interest in mixed stack charge-transfer (CT) crystals, made up by alternating π electron-donor and acceptor molecules, we focus attention on a forgotten donor, 1,1,4,4-tetrathiabutadiene (TTB), synthesized more than 35 years ago. We present a spectroscopic and computational characterization of the neutral TTB, and fully characterize the CT crystal with TCNQ. TTB-TCNQ is a mixed stack crystal, with limited degree of CT (about 0.1), despite TTB electron donating strength is only a little smaller than that of the famous TTF. This finding is explained by the small value of the Madelung energy, that we evaluate by a well tested computational approach.We thank the late Prof. Daniel J. Sandman for his help with the synthesis. We acknowledge the support of the EU with ERC StG2012-306826e-GAMES and of the MINECO of the Spanish Government (CTQ2016- 80030-R and SEV-2015-0496).Peer reviewe
High Performance Organic Field-Effect Transistors with Solid and Aqueous Dielectric Based on a Solution Sheared Sulfur-Bridged Annulene Derivative
No full textThin films of the organic semiconductor meso-diphenyl tetrathia[22]annulene[2,1,2,1] (DPTTA) are prepared for the first time employing solution-based techniques to fabricate organic field-effect transistors (OFETs). Homogeneous and crystalline films of this semiconductor are achieved, thanks to the synergic approach of employing blends of this material with polystyrene (PS) and the high throughput technique bar-assisted meniscus shearing (BAMS) with a hydrophobic bar. The resulting active layers exhibit state-of-the-art OFET performance with an average mobility of 1 cm2 V−1 s−1, threshold voltage close to 0 V, high on/off ratio, and sharp switch on. Furthermore, a DPTTA:PS formulation is optimized to prepare films suitable for their integration in electrolyte-gated field effect transistors operating in ultrapure water and 0.5 m NaCl aqueous solution. Such devices also reveal excellent performance with mobility values above 0.1 cm2 V−1 s−1, potentiometric sensitivity ≈200 µV, time response ≈9 ms, and long term stability in ultrapure water. Hence, this work supports the strategy of combining organic semiconductor:polymer blends with BAMS as a powerful route for achieving high performing devices, and also points out DPTTA as a highly promising material to be integrated in organic electronic devices.A.C., Q.Z. and M.R.A. equally contributed to this work. The authors thank the ERC StG2012-306826 e-GAMES project, the DGI (Spain) with project, FANCY CTQ2016-80030-R, the Generalitat de Catalunya (2014-SGR-17), the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496). Q.Z. acknowledges the China Scholarship Council, the National Natural Science Foundation (NSF) of China (11404266), and the Fundamental Research Funds for the Central Universities (Grant No. XDJK2014C081). F.L. gratefully acknowledges the “Juan de la Cierva” programme. A.C. and Q.Z. are enrolled in the Materials Science PhD Program of Universitat Autònoma de Barcelona.Peer reviewe
Light interception and yield response of cotton varieties to high density planting and fertilizers in sub-tropical India
No full textPlant density and optimum fertilization are two important agronomic practices to enhance productivity of cotton (Gossypium hirsutum L.) varieties. The objective of this study was to investigate the effect of high density planting (HDPS) and fertilization rate, especially their interactions, on yield, yield components of cotton varieties in sub-tropical India. Split-split plot design was adopted and replicated thrice. The main plots were assigned to low, medium and high plant densities (16.7, 13.3 and 11.1 plants/m2). Pre released cotton varieties TCH-1705 and LH-2298 were tested in low, moderate and high rates of fertilizers recommended for the region (100, 125 and 150 %) in sub-sub plots. Significantly higher seed cotton yield (1148 kg/ha) was achieved in narrow inter row spaced at 60 cm over normal plant row spacing of 90 cm (1025 kg/ha). Compact genotype TCH-1705 was out yielded (1146 kg/ha) over LH 2298(1044 kg/ha). Application of fertilizers at higher rate improved seed cotton yield (1232 kg/ha) Leaf area index (3.8) and light interception (0.98) over blanket recommendation. The results of the study inferred that seed cotton yield improvement was possible under HDPS production system with compact varieties grown at narrow spacing and higher fertilizer dose
Direct covalent grafting of an organic radical core on gold and silver
No full textThe functionalisation of surfaces with organic radicals, such as perchlorotriphenylmethyl (PTM) radicals or tris(2,4,6-trichloro-phenyl)methyl (TTM) radicals, is appealing for the development of molecular spintronic devices. Conventionally, organic radicals are chemisorbed to metal substrates by using long alkyl or aromatic spacers resulting in a weak spin–electron coupling between the radical and the substrate. To circumvent this problem, here we have employed a new design strategy for the fabrication of radical self-assembled monolayers (r-SAMs). This newly designed radical–anchor (R–A) molecule, a TTM based radical disulfide (1), can be easily synthesized and it was here characterized by electron spin resonance (ESR), cyclic voltammetry (CV) and superconducting quantum interference device magnetometry (SQUID). We have succeeded in fabricating TTM based r-SAMs by using thiolate bonds (Au–S and Ag–S) where the TTM cores are only one-atom distance from the metal surface for the first time. The resultant robust 1/Au and 1/Ag r-SAMs were well characterized, and the electrochemical and the magnetic properties were unambiguously confirmed, proving the persistence of the molecular spin.This work was funded by ERC StG 2012-306826 e-GAMES. The
authors also thank ITN iSwitch 642196 project, the Networking
Research Center on Bioengineering, Biomaterials and Nanomedicine
(CIBER-BBN), DGI (Spain) BE-WELL CTQ2013-40480-
R and FANCY CTQ2016-80030-R, and Generalitat de Catalunya
2014-SGR-17. The authors also acknowledge the Spanish
Ministry of Economy and Competitiveness, through the “Severo
Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-
0496). We thank Dr V. Lloveras for ESR spectroscopy characterization,
Mr A. Bernab´e for MALDI-TOF measurements and Dr
G. Sauthier from ICN2 for XPS and UPS measurements. We also
thank Dr N. Crivillers for useful discussions. S. T. B. and I. A.
acknowledge support from the Spanish MINECO grant
CTQ2015-64618-R grant and, in part, by Generalitat de Catalunya
grants 2014SGR97 and XRQTC. IA acknowledges the
Spanish Ministerio de Educaci´on Cultura y Deporte for a FPU
PhD scholarship. Access to supercomputer resources as provided through grants from the Red Espanola de Supercomputación is also acknowledged.Peer reviewe
Self-Assembly of an Organic Radical Thin Film and its Memory Function Investigated Using a Liquid Metal Electrode
No full textIn this work, the deposition of a persistent organic radical by thermal evaporation on gold, platinum and graphene is performed. The impact of the deposition parameters and the nature of the substrate on the molecular organization within the deposited film are investigated. The non-planarity of the molecule and the role of the molecule-molecule and molecule-substrate interactions are discussed. Ultraviolet photoelectron spectroscopy experiments demonstrate that the radical character, and hence its magnetic and redox properties, is preserved on the three surfaces. The optimized films are electrically characterized by top-contacting the film/substrate system using a liquid metal which permits to achieve a soft-contact avoiding damaging the layer. The hysteretic current versus voltage curves obtained from the electrical characterization points to the potential applicability of the studied system as an organic memory. Moreover, the demonstrated feasibility of using a liquid metal is an appealing approach towards the preparation of flexible devices.We thank Dr. Raphael Pfattner for the fruitful discussions. We thank Dr. Guillaume Sauthier from
the Catalan Institute of Nanoscience and Nanotechnology (ICN2) for the XPS measurements. This
work was supported by MINECO through the “Severo Ochoa” Programme for Centers of
Excellence in R&D (SEV-2015-0496) and the FUNMAT-FIP projects, the European Research
Council (ERC) StG 2012-306826 e-GAMES project. The authors also thank the CIBER-BBN, the
Dirección General de Investigación (DGI) (Spain) project FANCY CTQ2016-80030-R and the
Generalitat de Catalunya (2017-SGR-918).Peer reviewe
Effects of Integrated Weed Management Practices on Weed Parameters and Yield of Bt Cotton (Gossypium hirsutum L.)
No full textAim: To know the effect of integrated weed management on weed parameters and yield of bt cotton.
Study Design: Randomized complete block design.
Place and Duration of Study: College of Agriculture Farm, Bheemaraynagudi between July 2021 and Feb 2022.
Methodology: The field experiment was conducted during Kharif 2021 at Experimental block, College of Agriculture, Bheemarayanagudi. The soil of the experiment field was deep black clayey in texture. The experiment comprises 11 weed management practices viz., T1: Pendimethalin 38.7% CS @ 750 g a.i./ha as PE + Hand weeding @ 20-25 DAS and Intercultivation @ 55-60 DAS, T2: Pendimethalin 38.7 % CS @ 750 g a.i./ha as PE fb Pyrithiobac Sodium 10 EC @ 75g a.i./ha + Quizalofop ethyl 5 EC @ 37.5g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS. (Tank mix), T3 : Pendimethalin 38.7 % CS @ 750 g a.i./ha as PE fb Pyrithiobac Sodium 10 EC @ 50g a.i./ha + Quizalofop ethyl 5 EC @ 25 g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS, T4 :Pendimethalin 38.7 % CS @ 750 g a.i./ha as PE fb Pyrithiobac Sodium 10 EC @ 75g a.i./ha + Quizalofop ethyl 5 EC @ 37.5g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS, T5 : Pendimethalin 38.7 % CS @ 750 g a.i./ha as PE fb Pyrithiobac Sodium 10 EC @ 100g a.i./ha + Quizalofop ethyl 5 EC @ 50g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS, T6 : Pyrithiobac Sodium 10 EC @ 50g a.i./ha + Quizalofop ethyl 5 EC @ 25g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS, T7: Pyrithiobac Sodium 10 EC @ 75g a.i./ha + Quizalofop ethyl 5 EC @ 37.5g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS, T8: Pyrithiobac Sodium 10 EC @ 100g a.i./ha + Quizalofop ethyl 5 EC @ 50g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS, T9: Farmers practice (Hand weeding @ 25 DAS and 2 intercultivations @ 50 and 75 DAS), T10: Weedy check, T11: Weed free check.
Results: Among the treatments, application of pendimethalin 38.7 % CS @ 750 g a.i./ha as PE fb pyrithiobac sodium 10 EC @ 100 g a.i./ha + quizalofop ethyl 5 EC @ 50 g a.i./ha as PoE (combi-product) @ 25 DAS and intercultivation @ 55-60 DAS recorded significantly lower weed density and higher weed control efficiency (82.39 %), also recorded higher seed cotton yield (2495 kg ha-1) and stalk yield (4056 kg ha-1) over other treatments.
Conclusion: Application of Pendimethalin 38.7 % CS @ 750 g a.i./ha as PE fb Pyrithiobac Sodium 10 EC @ 100g a.i./ha + Quizalofop ethyl 5 EC @ 50g a.i./ha as PoE @ 25 DAS and Intercultivation @ 55-60 DAS was found effective in controlling the weeds with coupled with higher seed cotton yield
Significance of Weed Flora Identification and its Management on Bt Cotton (Gossypium hirsutum L.) Growing Tract of Tungabhadra Command Area
No full textAims: To identify the weed species in Bt cotton under Tunga-bhadra project command area and to study the effect of sequential application of pre- emergent (PE) and post- emergent herbicides (PoE) on weed growth and to know the efficiency of different weed control practices on weed species.
Study Design: The experiment was laid in RBD (Randomized Block Design).
Place and Duration of Study: The experiment was conducted at ICAR-Krishi Vigyan Kendra farm, UAS, Raichur situated in TBP command area during kharif season of 2018-19.
Methodology: The design was RBD with 11 treatments and replicated thrice. Gross plot size of the field was 7.2 m × 4.8 m and net plot size was 5.4 m ×3.6 m with spacing of 90 x 30 cm. The certified seeds of Jadoo Bt II Cotton with the test weight of 6.5 g was used for sowing. The crop duration was around 6 month
Results: Weed flora present in the Bt cotton field were identified and classified based on their morphology. It was divulged that; dicotyledonous weeds were dominant in cotton field. The sequential applications of metolachlor 50 % EC @ 1000 g a.i. ha-1 as PE fb pyrithiobac sodium 10 EC @ 125 g a.i. ha-1 as PoE @ 2-5 leaf stage of weeds fb Inter cultivation (IC) @ 60 DAS reported lower weed count and weed dry matter and reported the highest weed control efficiency (90.22 %) at harvest than the application of diuron 80 % WP as PE fb @ 1500 g a.i. and pendimethalin Pendimethalin 30 EC @ 1250 g a.i. ha-1 as PE followed by pyrithiobac sodium 10 EC @ 125 g a.i. ha-1 as PoE @ 2-5 leaf stage of weeds fb Inter cultivation (IC) @ 60 DAS.
Conclusion: Application of pre-emergent followed by post emergent herbicides control the early and later flush of weeds. It avoids the emergence of broad spectrum weed flushes and weed shift. Integrated herbicidal application along with intercultural operations was found better in keeping weeds under a threshold than following a single method
‐Heptacene on a Metallic Surface
No full textThe synthesis of long n-peri-acenes (n-PAs) is challenging as a result of their inherent open-shell radical character, which arises from the presence of parallel zigzag edges beyond a certain n value. They are considered as π-electron model systems to study magnetism in graphene nanostructures; being potential candidates in the fabrication of optoelectronic and spintronic devices. Here, we report the on-surface formation of the largest pristine member of the n-PA family, i.e. peri-heptacene (n=7, 7-PA), obtained on an Au(111) substrate under ultra-high vacuum conditions. Our high-resolution scanning tunneling microscopy investigations, complemented by theoretical simulations, provide insight into the chemical structure of this previously elusive compound. In addition, scanning tunneling spectroscopy reveals the antiferromagnetic open-shell singlet ground state of 7-PA, exhibiting singlet–triplet spin-flip inelastic excitations with an effective exchange coupling (Jeff) of 49 meV. © 2022 Wiley-VCH GmbH.This project has received funding from Comunidad de Madrid [projects QUIMTRONIC-CM (Y2018/NMT-4783), MAD2D,and NanoMagCost (P2018/NMT-4321)], ERC ConsolidatorGrant (ELECNANO, 766555), and Ministerio de Ciencia,Innovacion y Universidades (projects SpOrQuMat (PGC2018-098613-B-C21), CTQ2017-83531-R, PID2019-108532GB-I00,and CTQ2016-81911-REDT). IMDEA Nanociencia is appreciative of support from the “Severo Ochoa” Programme forCenters of Excellence in R&D (MINECO, grant SEV-2016-0686). The EU Graphene Flagship (Graphene Core 3,881603), ERC Consolidator Grant (T2DCP, 819698), the German Research Foundation (DFG) within the Cluster ofExcellence “Center for Advancing Electronics Dresden (cfaed)and the DFG-SNSF Research Project (EnhanTopo, No.429265950) are acknowledged for financial support. Weappreciate funding from the Praemium Academie of the Academy of Science of the Czech Republic and the CzechNa-noLab Research Infrastructure supported by MEYS CR(LM2018110). P.J. thanks the support of the GACR 2013692X. J.I.U. acknowledges the European Union’s Horizon2020 research and innovation programme under the MarieSkłodowska-Curie grant agreement No [886314].Peer reviewe
Modified planting geometry and fertilizer rate on productivity of corn (Zea mays L.) in Vertisols
No full textA field experiment was conducted at Raichur, Karnataka with an objective to find out production potential of grain corn planted in clumps and rate of fertilizer application. Design followed was split plot and repeated thrice with rate of fertilizer application as main factor and planting geometry as sub factor. Treatments consists of planting corn at 2, 3, 4 seeds/hill compared with single seeds/hill (60 cm x 20 cm) and farmers practice uneven spacing. In clumped plants inter row spacing is similar (60 cm) and intra row distance is differ to maintain uniform plant density (83,333 plants/ha) in each treatment. Recommended dose of fertilizers (RDF) was applied in 2 splits and 150% RDF in 3 splits. Results revealed that planting 2 seeds /hill at 60 cm x 40 cm recorded significantly higher yield, economics of corn as compared to 3 and 4 seeds/hill and farmers practice. As increased plant population per hill maintains higher soil moisture at 75 days after planting (7.5-9.4%) and lower dry matter per plant at harvest (236.3 to 185.5 g) as compared to conventional planting. Application of higher (150%) fertilizers in 3 splits recorded higher dry matter production, grain yield, and economic returns over RDF. This may be useful strategy for corn productivity enhancement by clump planting with higher fertilizer rate
Effect of Nano Fertilizers on Growth, Yield, Nutrient Uptake and Soil Microbiology of Kharif Sorghum
No full textAims: Foliar nutrition is aimed to eliminate the problems of fixation and immobilization of nutrients. Hence, foliar nutrition is being recognized as a significant way of fertilizing modern agriculture, especially under rainfed conditions. Nano fertilizers because of smaller size and higher surface area are efficient as compared to conventional and produce better results when used in combined form.
Study Design: The experiment was laid out in Randomized complete block design with three replications.
Place and Duration of Study: A field experiment was conducted in medium black soils at Agricultural Research Station, Hagari, during Kharif 2022.
Methodology: There were ten treatment combinations, consisting of different doses of RDF (50 % RNP, 75 % RNP and 100 % RDF and absolute control) with different doses of nano urea and Dap sprayed at 30 and 45 DAS for CSH-16 hybrid of sorghum.
Results: Application of 75% RNP as basal + nano urea & DAP spray @ 1.5 ml l-1 each at 30 and 45 DAS recorded significantly higher number of leaves, leaf area and leaf area index. It also produced higher earhead length (35.9 cm), number of grains earhead-1 (2207), grain weight (57 g plant-1) and test weight (29.3 g 1000 grains-1). Nutrient content and uptake also showed higher values for the same treatment along with the nutrient use efficiency indices. Whereas, significant reduction in soil microbes was noticed by the application of treatment.
Conclusion: Combined application of conventional and nano fertilizers helped to increase growth, growth attributes like number of leaves, leaf area, leaf area index, yield attributes, nutrient content, nutrient uptake and nutrient use efficiency of sorghum
