Low Gap Research Articles

Edge-Decorated Polycyclic Aromatic Hydrocarbons by an Oxidative Coupling Approach.

Oxidative phenol coupling reduces reliance on halo/metalated substrates used in conventional redox neutral couplings. A new strategy for constructing polycyclic aromatic hydrocarbons (PAHs) that incorporates oxidative phenol coupling is outlined in a three-stage approach: oxidative fragment coupling, linking of the two resultant units, and oxidative cyclization. The protocol allows rapid assembly of both planar and helical systems with a high degree of edge functionalization. The incorporation of 12 alkoxy groups on systems with 12 rings gave rise to lower optical gaps compared to systems with a lesser degree of edge functionalization.

From inflation to black hole mergers and back again: Gravitational-wave data-driven constraints on inflationary scenarios with a first-principle model of primordial black holes across the QCD epoch

Recent population studies have searched for a subpopulation of primordial black holes (PBHs) in the gravitational-wave (GW) events so far detected by LIGO/Virgo/KAGRA (LVK), in most cases adopting a phenomenological PBH mass distribution. When deriving such population from first principles in the standard scenario, however, the equation of state of the Universe at the time of PBH formation may strongly affect the PBH abundance and mass distribution, which ultimately depend on the power spectrum of cosmological perturbations. Here we improve on previous population studies on several aspects: (i) we adopt state-of-the-art PBH formation models describing the collapse of cosmological perturbations across the QCD epoch; (ii) we perform the first Bayesian multi-population inference on GW data including PBHs and directly using power spectrum parameters instead of phenomenological distributions; (iii) we critically confront the PBH scenario with LVK phenomenological models describing the GWTC-3 catalog both in the neutron-star and in the BH mass ranges, also considering PBHs as subpopulation of the total events. Our results confirm that LVK observations prevent the majority of the dark matter to be in the form of stellar mass PBHs. We find that the best fit PBH model can comprise a small fraction of the total events, in particular it can naturally explain events in the mass gaps. If the lower mass-gap event GW190814 is interpreted as a PBH binary, we predict that LVK should detect up to a few subsolar mergers and one to $\approx 30$ lower mass gap events during the upcoming O4 and O5 runs. Finally, mapping back the best-fit power spectrum into an ultra slow-roll inflationary scenario, we show that the latter predicts detectable PBH mergers in the LVK band, a stochastic GW background detectable by current and future instruments, and may include the entirety of dark matter in asteroid-mass PBHs.

Geometrical effect of natural convection in an air channel with a cavity at the turning section on thermal behavior and heat removal performance

The geometrical effect of natural convection in an air channel with a cavity at the turning section was investigated experimentally by controlling the vertical upper gap (G, 100–75 mm) and horizontal lower channel gap (B, 100 - 300 mm) and varying the heat load conditions (P, 1.35–6.20 kW). The thermal behavior in the channel was considered in terms of the temperature distributions of the walls, and the air temperature field was estimated from the measured air temperature. Additionally, the heat removal performance was analyzed for changes in each parameter to find the critical design parameter on cooling performance.The heat load condition positively affected the heat removal performance, but it did not affect the trend of the wall temperature distributions or the shape of the temperature field in the channel. A lower channel gap directly affected the cooling in the lower channel (cavity) between the lower curved wall and bottom but did not appreciably affect the cooling in the upper vertical channel between both vertical walls and overall heat removal performance (RSDMax = 3.2 %). As a result, the most critical parameter was the upper vertical channel gap because it affected both lower and upper channels and played a vital role in determining the overall heat transfer performance (RSDMax = 11.0 %). Additionally, it was confirmed that the location where the peak wall temperature appeared changed as the vertical gap size was altered.Interestingly, we found that the transition phenomenon eliminating the entrance effect occurred above the mid-height of the vertical channel in all experimental cases, and it was directly related to the heat removal performance. The temperature profiles developed smoothly along the height in only the G175 cases, which were the maximum heat removal performance cases, owing to the minimized entrance effect in the channel. In contrast, the temperature profiles below the mid-height of the vertical channel changed rapidly due to the entrance effect in other cases.

Dual band symmetry-protected terahertz bound states in the continuum inside the spoof localized surface plasmon induced-transparency windows

A new phenomenon of dual band symmetry-protected bound state in the continuum (BIC) is revealed inside the plasmon-induced transparency (PIT) windows. A metasurface of circular periodically grooved cavity integrated with a complimentary symmetric double-gap split-ring resonator (DSRR) is employed. Intrinsic spoof localized surface plasmon (SLSP) interferes destructively with dipole oscillation of DSRR. A PIT phenomenon is generated between the two bright side-modes (ν 1 = 0.49 THz, ν 2 = 0.79 THz) when the metasurface is in C 2v symmetry. The displacement of upper-gap (while keeping the lower gap fixed) of DSRR results in three dark modes inside the frequency range of induced transparency windows, two of which are quasi-BIC. At a relatively low degree of asymmetry, one anapole dark mode ν 3 = 0.55 THz dominate quasi-BIC I and another magnetic dipole coupled quadrupole dark mode ν 4 = 0.75 THz dominates quasi-BIC II. At a relatively larger degree of asymmetry, one more dark mode ν 5 = 0.75 THz occurs in the frequency spectra as is a tilted SLSP intrinsic mode. Since the dark mode ν 5 is not sensitive to the asymmetric displacement of DRSS. A coupled five oscillators’ model reveal that coupling strength with free space and the damping ratios are attributed to the asymmetry of the structure. The leaky channels of both BICs have a much lower damping ratio than the bright side-mode of PIT. The coupling coefficients indicate that quasi-BIC I is affiliated to the lower frequency bright side-mode ν 1, and quasi-BIC II is affiliated to the higher frequency bright side-mode ν 2. The measured Q factors fit well with the relation function of geometric asymmetry, among which the maximum Q factor measured of the quasi-BIC-II exceeds 20. The realization of above results paves a new way to achieve dual band terahertz quasi-BIC by tuning SLSP-induced transparency window. This provides a feasible solution for the design of multi-band terahertz thin-film sensors.

Designing of gigantic first-order hyperpolarizability molecules via joining the promising organic fragments: a DFT study.

A suitable substitution of carbazole with a π-spacer group like cyanoethynylethene offers exciting future opportunities in terms of smart nonlinear optical material. In the quest of better organic nonlinear optical material, we have designed a series of derivatives based on carbazole and cyanoethynylethene fragment combinations in a unique fashion by employing the density functional (DFT) methods. The calculated time-dependent density functional theory (TD-DFT) calculations infer that the gigantic first static hyperpolarizability (βtot) values are due to a lower energy gap and higher transition dipole moment for the crucial electronic transition. Furthermore, to see the in-depth execution for enhanced second-order nonlinear optics and the structure property relationship on nonlinear optics (NLO) behavior, we have performed frontier molecular orbitals (FMO), density of state (DOS), and transition density matrix (TDM). Furthermore, CAM-B3LYP functional-based calculated results infer that the designed molecule 10 show the first static hyperpolarizability is 923.93 × 10-30 esu which is 69 times larger than that of p-nitroaniline.

Environmentally affable and highly efficient donor material based on cyclopentadithiophene (CPDT) framework for remarkable organic solar cells

The quantum chemical exploration of highly conjugated D-π-A type molecules based on cyclopentadithiophene (CPDT) core is anticipated to recommend novel organic materials for efficient organic solar cells (OSCs). Five new conjugated molecules (C1–C5) were designed by drafting of reference CR through thiophene bridged end caped acceptors and their geometric, as well as optoelectronic properties, were investigated at MPW1PW91/6-31G (d,p) functional. All the newly tailored chromophores (C1–C5) proclaimed lower energy gap values (ranging from 1.95 to 2.19 eV) than the reference CR (3.18 eV). TD-DFT calculations of all the newly designed molecules revealed higher λmax in the range 500–514 nm than the reference CR (483.2 nm) in dichloromethane solvent. Lower excitation energies (1.79–1.94 eV) and higher dipole moment (4.84–18.37 D) for all the drafted compounds (C1–C5) than reference CR were observed which proclaimed efficient charge transfer. Simulations of global reactivity parameters like hardness, chemical potential, softness and electrophilicity manifested all these molecules (C1–C5) to be reactive and thermally stable. The small values of reorganization energies for electron and hole exhibited high electron-hole mobilities and low charge recombination. The power conversion efficiency (PCE) parameters were simulated by scaling the HOMO of designed molecules acting as a donor with LUMO of PC61BM acceptor. All the designed molecules (C1–C5) demonstrated high open circuit voltage (0.67–0.92 V) than the reference (0.49 V) which is favorable for enhancement of PCE. Also, the higher values of fill factor (FF) ranging from 0.8417 to 0.8677 for newly designed chromophores increased the PCE than reference CR (0.8015). The results demonstrated the suitability of these donor molecules designed by deliberated technique, opening a new path for the development of donor's contributors to OSCs and may prove efficient materials for fabrication of future OSCs.

Unveiling the dehydrogenation mechanism of 1,1,6,6-tetracyclohexylhexane: A first-principles study

Liquid organic hydrogen carriers (LOHCs) have been attractive as the technology to decarbonize the mobility sector. In this work, the dehydrogenation of 1,1,6,6-tetracyclohexylhexane (7.29 wt% H2) was explored using various DFT-based approaches. The effect of BN substitution on the dehydrogenation was explored based on the changes in the dehydrogenation energies in response to BN substitution. The BN substitution was shown to clearly lower the dehydrogenation energy. The energy barrier for dehydrogenation was also found to be influenced by the BN substitution. The dehydrogenated system was found to possess a lower HOMO-LUMO gap than the hydrogenated one, showing the chemical reactivity of the dehydrogenated form of the studied LOHC.

Influence of Channel‐Spanning Engineered Logjam Structures on Channel Hydrodynamics

AbstractNature‐based solutions to flood risk management, such as engineered logjams (ELJs), contribute to the reintroduction of wood in rivers. As part of stream restoration, and utilized in tributaries, ELJs increase upstream water levels, causing the flow to spill onto surrounding floodplains, resulting in the desynchronization of peak flows in a river network. To understand the effect of ELJs on local river hydrodynamics, we experimentally investigate the flow field upstream and downstream of six ELJs, using acoustic Doppler velocimetry and flow visualization. We consider channel‐spanning structures designed with a gap (b0) underneath, allowing unhindered baseflow. Our results revealed that upstream of the logjams, flow diverted toward the lower gap, creating a primary jet exiting underneath the structures, whose strength depends on the physical logjam design. Maximum jet velocities remained constant until a downstream distance of 4b0 for all logjams. The upper wake was structure‐dependent, with logjam structures allowing distinct internal flow paths generating secondary jets, which influenced near wake decay (x < 4b0) and turbulent mixing. The highest turbulence in the near wake was found for the non‐porous and short, porous logjam designs, while the upper wake of all long, porous logjams was characterized by low turbulent kinetic energy levels. Far wake decay (x > 4b0) was self‐similar for all logjams and resulted in near flow recovery at downstream streamwise distances greater than 35b0. ELJs are likely to enhance bed shear stress, increasing the risk of local scour and sediment mobilization. Our study expands the current knowledge of ELJ hydrodynamics and highlights potential implications for the riverine ecosystem.

Synthesis, characterization, DFT studies, and molecular modeling of hydrazinelidene‐3‐oxo‐3‐(p‐olyl) propanal derivatives as potential candidate for Hepatitis B and C treatment

AbstractSerious liver conditions including cirrhosis, hepatocellular carcinoma, and liver failure can be brought on by hepatitis B and C (HBV and HCV) infection. In our study, compound H_B and H_E were synthesized, spectroscopically, theoretically characterized, and investigated as potential drug for HBV and HCV. The stability of the investigated compounds as well as their Inter‐ and intramolecular interactions were investigated using the density functional theory with the B3LYP/6‐311+G (d, p) basis set. Lower energy gaps for studied compounds indicate compound ds to be reactive. The maximal absorption wavelengths of the substances under investigation were ascertained using the UV absorption spectrum. The optical property of the compounds under investigation was also calculated. Various vibrational modes displayed by functional groups present in the examined compounds were considered. Thereafter, docking was performed to determine the compatibility of compounds in study with selected hepatitis B and C proteins in comparison to recommended drugs Sofosbuvir and lamivudine. The results of molecular docking were based on binding affinity. Compound H_E, with a binding affinity of ‐7.6 kcal/mol has more potential in treating hepatitis than H_B, which has a binding affinity of ‐7.1 kcal/mol and is also a better anti‐hepatic agent than standard drugs sofosbuvir and lamivudine with lower binding affinities. Hence, H_E has the potential to treat HBV and HCV.

On the Design of Cylindrical Magnetorheological Clutches

Magnetorheological fluids (MRFs) exhibit variable mechanical properties in response to magnetic stimuli. Thanks to their rapid and reversible viscosity changes, MRFs can be utilized in a variety of applications including torque transmission devices such as clutches. In this work, the geometrical design of cylindrical MR clutches is investigated with the aim of optimizing the torque transmission capability. Effects of design parameters such as radius, gap size, effective length, and MRF volume are investigated in the presence of variable magnetic field. Magneto-mechanical behavior of some MR fluids with different particle content are investigated by means of two different constitutive models to simulate the clutch performance in a range of geometrical parameters. It is shown that the transmitted torque increases nonlinearly by inner radius of the clutch, for example, in the studied range, 150% higher torque is achieved for only 40% larger radius. The clutch’s gap size does not much affect the torque, however, since it significantly affects the required volume of MRF, a lower gap size is favorable. The torque is also calculated for constant volumes of the MRFs. At a certain volume, although a higher radius translates to a shorter length, it is still favorable. For example, a 40% increase in the design radius, almost doubles the transmitted torque for both the studied MRFs. Moreover, a clutch filled by an MRF with higher particle content can transmit higher torques. It is also concluded that increasing the clutch’s radii is an easier way to improve the mean torque while altering the applied magnetic field is a better way to adjust the range of achievable torques. The simulations also demonstrate the importance of an accurate and reliable constitutive model in the design of MR devices. It is shown that Bingham model is not reliable at high magnetic fields as it underestimates the transmitted torque though calibrated at each field intensity. However, the employed nonlinear model provides more reliable results by only being calibrated at an arbitrary field.

Simulation Calculation Verification of Graphene Oxide-Decorated Silver Nanoparticles Growing on Titania Nanotube Array as SERS Sensor Substrate

Graphene oxide-decorated silver nanoparticles growing on titania nanotube array (GO/Ag/TiO2 NTA) were designed as active Surface-enhanced Raman scattering (SERS) sensor substrates for sensitive determination of the organic compound bisphenol A. The theoretical simulation calculation and experimental measurements have been adopted to investigate the electronic and sensing properties of GO/Ag/TiO2 NTA SERS substrate. The molecule adsorption and surface energy are applied to investigate the interfacial interaction between the SERS substrate and the organic molecule. The Raman spectrum response intensity and the electron transfer behavior are applied to investigate sensing activity of GO/Ag/TiO2 NTA SERS substrate. The specific adsorption amount of BPA is 3.3, 7.1, and 52.4 nmol cm−2 for TiO2, Ag/TiO2, and GO/Ag/TiO2 NTA, respectively, presenting superior adsorption and aggregation capability. GO/Ag/TiO2 NTA SERS sensor accordingly achieves the low detection limit of 5 × 10−7 M for bisphenol A molecule. The density functional theory simulation calculation proves that GO/Ag/TiO2 reveals a higher density of states, lower HOMO-LUMO gap, stronger electrostatic interaction, and similar band gaps in comparison with Ag/TiO2. Binary-interfaced GO/Ag/TiO2 presents a more declined molecule structure surface energy of 5.87 eV rather than 4.12 eV for mono-interfaced Ag/TiO2. GO/Ag/TiO2 also exhibits a more declined surface adsorption energy of 7.81 eV rather than 4.32 eV for Ag/TiO2 in the adsorption of bisphenol A. The simulation calculation verification results well confirm the superior activity of GO/Ag/TiO2 NTA substrate for sensitive detection and quantitative determination of the organic compound bisphenol A.

Drivers’ gap acceptance during parking maneuvers as a basis for initiating driving actions in automated vehicles

As a social system, traffic requires the coordination between different involved road users, particularly in shared spaces (e.g., parking areas) with fewer statutory regulations and hence more ambiguous encounters. By anticipating the development of driving scenes and adapting own driving actions, drivers maintain individually varying safety margins, such as accepted time gaps, to surrounding traffic participants. However, drivers’ gap acceptance (GA) was shown to be influenced by situational factors and driver characteristics. In order to apply expectable interactions in mixed traffic, involving manual and automated vehicles (AVs), intuitive gaps in traffic flow need to be selected by AVs when initiating parking actions. Derived time gaps of manual drivers could provide a basic orientation for intuitive driving functions in AVs. Thus, the current experimental study assessed manual drivers’ GA in a parking area scenario. Real-world video material was used to investigate the effects of interaction partners, their encountering speeds and drivers’ age and sensation seeking on GA. In the study, 42 participants (including two age groups: 18–30 years vs ≥ 45 years) indicated their GA when initiating a left-turn parking maneuver in front of approaching vehicles. The study examined three interaction partners (motorcycle, passenger car, truck), each approaching at six different speed levels (10–35 km/h). The results revealed that selected time gaps increased as vehicle size increased, with the largest GA for the truck and the smallest gaps for the motorcycle. Moreover, time gaps decreased at higher approaching speeds of the interaction partners. In addition, older participants selected more conservative gaps and participants with higher sensation seeking scores accepted lower time gaps to initiate a parking maneuver. The results of the current study revealed that there is no one single time gap that is always considered as appropriate to initiate parking actions. For intuitive interaction capabilities in AVs and to support smooth encounters in mixed traffic, the speed of the approaching interaction partners should be considered as an essential situational factor when initiating parking maneuvers. To consider individual driving style preferences (e.g., due to driver age) and support user acceptance, selectable driving style profiles should be available in AVs as a form of customization.

Promoting Electrocatalytic CO2 Reduction to CH4 by Copper Porphyrin with Donor-Acceptor Structures.

Molecular catalysts have been receiving increasingly attention in the electrochemical CO2 reduction reaction (CO2 RR) with attractive features such as precise catalytic sites and tunable ligands. However, the insufficient activity and low selectivity of deep reduction products restrain the utilization of molecular catalysts in CO2 RR. Herein, a donor-acceptor modified Cu porphyrin (CuTAPP) is developed, in which amino groups are linked to donate electrons toward the central CuN4 site to enhance the CO2 RR activity. The CuTAPP catalyst exhibited an excellent CO2 -to-CH4 electroreduction performance, including a high CH4 partial current density of 290.5mA cm-2 and a corresponding Faradaic efficiency of 54.8% at -1.63V versus reversible hydrogen electrode in flow cells. Density functional theory calculations indicated that CuTAPP presented a much lower energy gap in the pathway of producing *CHO than Cu porphyrin without amino group modification. This work suggests a useful strategy of introducing designed donor-acceptor structures into molecular catalysts for enhancing electrochemical CO2 conversion toward deep reduction products.

Synthesis of 4-Aminopyrazol-5-ols as Edaravone Analogs and Their Antioxidant Activity.

One of the powerful antioxidants used clinically is Edaravone (EDA). We synthesized a series of new EDA analogs, 4-aminopyrazol-5-ol hydrochlorides, including polyfluoroalkyl derivatives, via the reduction of 4-hydroxyiminopyrazol-5-ones. The primary antioxidant activity of the compounds in comparison with EDA was investigated in vitro using ABTS, FRAP, and ORAC tests. In all tests, 4-Amino-3-pyrazol-5-ols were effective. The lead compound, 4-amino-3-methyl-1-phenylpyrazol-5-ol hydrochloride (APH), showed the following activities: ABTS, 0.93 TEAC; FRAP, 0.98 TE; and ORAC, 4.39 TE. APH and its NH-analog were not cytotoxic against cultured normal human fibroblasts even at 100 μM, in contrast to EDA. According to QM calculations, 4-aminopyrazolols were characterized by lower gaps, IP, and η compared to 4-hydroxyiminopyrazol-5-ones, consistent with their higher antioxidant activities in ABTS and FRAP tests, realized by the SET mechanism. The radical-scavenging action evaluated in the ORAC test occurred by the HAT mechanism through OH bond breaking in all compounds, directly dependent on the dissociation energy of the OH bond. All the studied compounds demonstrated the absence of anticholinesterase activity and moderate inhibition of CES by some 4-aminopyrazolols. Thus, the lead compound APH was found to be a good antioxidant with the potential to be developed as a novel therapeutic drug candidate in the treatment of diseases associated with oxidative stress.

Theoretical study of CO adsorption on FexCuy (x + y = 3) clusters and reactive activity of their carbonyl complexes

In this paper, the adsorption of CO on FexCuy (x + y = 3) clusters was studied by BPW91 method, and all conceivable geometries and electronic states of carbonyl complexes were explored. The results show that bimetallic clusters tend to have higher stepwise CO adsorption energy than corresponding pure clusters, and the adsorption capacity of FeCu2 with CO is substantially larger than that of other carbonyl complexes. The CO bond length and CO stretching indicated that the CO bond is significantly weakened in Fe3(CO)6. In addition, the frontier molecular orbital theory was used to analyze the effect of the second element in the ligand reactions, which also confirmed that the reactions of CO with bimetallic clusters are easier than that of pure cluster systems. Finally, the energy gaps of HOMO and LUMO were used to explore the reactive activity of carbonyl complexes, and it was found that the Fe2Cu(CO)1 has lower energy gap than that of other carbonyl complexes. This suggests that it may be possible to tune bimetallic cluster to get higher activity carbonyl complexes in the reactions.

The influence of current density dependent Li2CO3 properties on the discharge and charge reactions of Li-CO2/O2 battery

As a promising energy storage technology, Li-CO2/O2 batteries not only deliver ultrahigh discharge capacity but also capture and convert CO2 into renewable energy. The exploration into the deposition and decomposition kinetics of discharge product (Li2CO3) is urgent for the high thermodynamic stability. Herein, the influence of current density on the essential characteristics of Li2CO3 has been explored. The results show that the Li2CO3 with poor crystallinity and elliptical disk morphology can be obtained at medium current density, corresponding to the excellent electrochemical performance including ultrahigh capacity of 5800 mA h/g, lower discharge-charge gap of 1.15 V, and long-term cycle life of 80 cycles. In addition, the morphology and crystallinity of Li2CO3 are tailored by the relative energy barriers for electron migration and O2- generation. At a medium current density (500 mA/g), the accelerated electron migration can realize the nucleation rate equivalent to growth one of Li2CO3. At this time, Li2CO3 will uniformly deposit on the cathode surface, forming elliptical disk morphology with poor crystallinity. Obviously, this work provides new sights for promoting the development of Li-CO2/O2 battery through rational design of catalysts to accelerate the deposition and decomposition processes of Li2CO3.

Dielectric response and density functional theory assessment of fluorinated dicationic pyridinium ionic liquids

AbstractThis study represent the synthesis and electrical conductivity of two focused dicationic pyridinium ionic liquids (DiILs) carrying tetrafluoroborate and/or hexafluorophosphate as counter anion. Thus, the synthesis required quaternization of the pyridine nitrogen atoms first, followed by a metathetical exchange reaction to produce the task‐specific ILs bearing tetrafluoroborate and hexafluorophosphate as counter anions. The resulting DiILs were characterized by NMR and MS spectroscopy. The dielectric constant and the conductivity of the targeted DiILs were analyzed in detail, within a frequency‐range of 1 KHz to 0.3 MHz and a temperature range of 25–100°C. Density functional theoretical (DFT) calculations were also carried out at the base site, B3LYP 6–311 g (d,p), for the Syn/E isomers of the investigated ionic liquids (ILs). We found non‐coplanar molecular geometries with a twist angle of the Schiff base, dependent on the type of counter ion present. The energy levels and differences of the frontier molecular orbitals (FMOs) were also predicted using DFT calculations. The results revealed that the ILs incorporating BF4− as counter anions showed high HOMO and LUMO values with a higher energy gap, while low FMOs with a lower energy gap were recorded for the derivative encompassing PF6− counter anions. These findings were used to help explain the dielectric properties of the investigated DiILs.

Zinc(II) complexes of azadipyrromethene: Effect of nature and placement of solubilizing groups on structural, thermal, electrochemical and optical properties

Zinc(II) complexes of azadipyrromethenes are non-planar chromophores with strong absorption in the visible to NIR and are promising n-type materials for organic solar cells. To increase solubility and tune their properties, we incorporated hexyl or hexyloxy solubilizing groups either on the distal or proximal phenyls of bis[2,6-diphenylethynyl-1,3,7,9-tetraphenyl azadipyrromethene] zinc(II) (Zn(WS3)2). Crystal structures confirm the typical distorted tetrahedral geometry for these types of complexes and show that the solubilizing groups on the distal phenyls extend away from the conjugated core whereas groups on proximal phenyls interact with the other ligand. Differential scanning calorimetry measurement indicated that crystals of distal-substituted complexes have two endothermic peaks: solubilizing groups ‘melting’ and complex melting, whereas the proximal-substituted complexes show one exothermic crystallization peak and one endothermic melting peak. Electrochemical and optical properties varied as expected for ADP-based complexes: the presence of electron rich groups at the proximal substitutions resulted in lower oxidation potentials, higher HOMO levels, red-shifted absorption and lower optical gap than distal substitutions, and the effect was greater for hexyloxy than hexyl. Upon thermal annealing, films of the hexyloxy-substituted complexes strongly aggregated and showed crystal features under a polarized microscope, indicating that hexyloxy groups drive ordered self-assembly, especially when placed on distal phenyls. The ability to guide solid-state self-assembly of these non-planar chromophores using solubilizing groups have the potential to improve their charge carrier mobility and performance in opto-electronic applications such as organic solar cells, and photodetectors.

Performance of Pigeonpea (Cajanus cajan L.) Varieties Sown on Ridge under Front Line Demonstration at Farmer’s Field in Deoria District of Uttar Pradesh, India

Aims: The production of pigeon pea is lower than the other pulse crops due to non-adoption of recommended high-yielding varieties and advanced technologies by the farming community in the eastern plains of Uttar Pradesh. To replace this anomalous, we conducted 152 front-line demonstrations (FLDs) at farmers' fields in various adopted villages by Krishi Vigyan Kendra, Deoria.
 Place and Duration of Study: The study was carried out by the Krishi Vigyan Kendra, Malhana, Deoria, under the Indian Institute of Vegetable Research, Varanasi, UP. A total of 90, 12 and 50 FLDs were conducted sown on ridge method with three varieties of pigeon pea (Narendra Arhar 1, Pusa Bahar and Narendra Arhar 2) from 2014-15 to 2018-19 respectively.
 Methodology: Conducted 152 front-line demonstrations (FLDs) at farmers' fields in various adopted villages by Krishi Vigyan Kendra, Deoria. Cultivation practices comprised under FLD viz. improved varieties, sowing methods, irrigation, date of sowing, seed treatment, spacing, balance use of fertilizers, intercultural operations, and plant protection measures etc.
 Results: Showed an increase in yield of pigeon pea varieties sown on ridge from 4.76–39.20% over traditional cultivation practices. As presented in Fig. 3, the technology gap was highest in Narendra Arhar 1 (1680 kg/ha) during 2016-17 and lowest in Narendra Arhar 2 (340 kg/ha) during 2018-19. The analysis of data for extension gap showed that Narendra Arhar 2 had the highest gap (540 kg/ha) during 2017-18 and Narendra Arhar 1 had the lowest gap (60 kg/ha) during 2016-17. The technology index was highest (56%) in Narendra Arhar 1 in 2016-17 and lowest (15%) in Narendra Arhar 2 in 2018-19.
 Conclusion: The lower the value of the technology index, the more feasible the technology is in the eastern plains of UP.

Occupational tasks and wage inequality in West Germany: A decomposition analysis

We study the role of occupational tasks as drivers of West German wage inequality. We match administrative wage data with longitudinal task data, which allow us to account for within-occupation changes in task content over time. We run RIF regression-based decompositions to quantify the contribution of changes in the returns to tasks to overall changes in the wage distribution from 1978 to 2006. We find that changes in the returns to tasks explain up to half of the increase in wage inequality since the 1990s, both at the top and the bottom of the wage distribution. Specifically, abstract tasks drive the upper wage gap, while interactive and routine tasks drive the lower wage gap. Importantly, we find low-wage occupations to have the highest routine task intensity. The association between occupational tasks and West German wage inequality is thus both stronger and different than prior research has found.