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Purpose: The purpose of the paper is to design a nonlinear dynamic inversion (NDI) based robust fault-tolerant control (FTC) for aircraft longitudinal dynamics subject to system nonlinearities, aerodynamic parametric variations, external wind disturbances and fault/failure in actuator. Design/methodology/approach: An uncertainty and disturbance estimator (UDE) technique is used to provide estimate of total disturbance enabling its rejection and thereby achieving robustness to the proposed NDI controller. As needed in the NDI design, the successive derivatives of the output are obtained through an UDE robustified observer making the design implementable. Further, a control allocation scheme consigns control command from primary actuator to the secondary one in the event of fault/failure in the primary actuator. Findings: The robustness is achieved against the perturbations mentioned above in the presence of actuator fault/failure. Practical implications: Lyapunov analysis proves practical stability of the controller–observer structure. The efficacy and superiority of the proposed design has been demonstrated through Monte-Carlo simulation. Originality/value: Unlike in many FTC designs, robustness is provided against system nonlinearities, aerodynamic parametric variations, external wind disturbances and sinusoidal input disturbance using a single control law which caters for fault-free, as well as faulty actuator scenario. [ABSTRACT FROM AUTHOR]

A robust controller for an octocopter is essential for flight stability. The presence of matched and unmatched disturbances can deteriorate a stable performance. This work proposes a robust controller for an octocopter to reject the matched and unmatched disturbances. The effects of fast varying external disturbances and parametric uncertainty on octocopter are considered matched disturbances and sensor measurement noise is modeled as unmatched disturbances. To alleviate the effects of disturbances an alpha uncertainty and disturbance estimator based integral sliding mode (ISMC-Alpha UDE) control law is proposed. The Lyapunov theory is used for stability analysis of the proposed ISMC-Alpha UDE control law. Comparative numerical simulations along with root mean square error (RMSE) analysis are presented to show the better performance of the proposed controller. The proposed controller offers reduced and smooth control efforts to achieve robust state tracking performance by mitigating the effects of matched and unmatched disturbances. The Monte Carlo simulations are performed to validate the efficacy of the proposed design. [ABSTRACT FROM AUTHOR]

Context: Quantum mechanical calculations involving electron correlation, frequency dispersion, and solvent effects were carried out to examine the second-order nonlinear optical response of various acceptor, X (-CF3, -CN, -NO2) substituted in N,N-dimethylaniline (DMA) and julolidine(JLD). Here, both DMA and JLD acts as donor and the three substituted groups, X (-CF3, -CN and -NO2) at the para position of both the ring systems as acceptor. The NLO response (βHRS) of -CF3 and -CN substituted DMA and JLD is relatively lower compared to DMA-NO2 and JLD-NO2. The charge distribution is found higher in case of -NO2 substituted DMA and JLD (±443 and ±449) compared to their -CF3 or –CN substitution. Electronic characteristics such as UV-Vis absorption spectra, crucial excited state parameters and charge transfer contribution to βHRS have been used to explain the NLO parameter of DMA-X and JLD-X. Variation of the incident optical frequency of light shows fluctuation of βHRS value and highest values of βHRS are obtain at the λmax frequency of each compound. Solvent polarity variation study on βHRS shows that βHRS varies linearly with the Kirkwood-Onsagar dielectric factor (D). Methods: All computational studies have been carried out using density functional theory (DFT) based method. Since CAM-B3LYP based hybrid functional improves the asymptotic behavior of the exchange interaction by dividing into short-range and long-range components, first hyperpolarizability values in the present study were computed using DFT/ CAM-B3LYP/ 6-31G+(d,p) level of theory. [ABSTRACT FROM AUTHOR]

Purpose: The requirement of robust cooperative control is essential to achieve consensus between unmanned aerial vehicles (UAVs) operating in swarm formation. Often the performance of these swarm formations is affected by wind gust disturbances. This study proposes an effective robust consensus protocol, which will ensure the UAVs in swam formation to collectively meet the desired objective in real-time scenario. Design/methodology/approach: In this work, the swarm of UAVs are modeled as multiagent systems by using the concepts of algebraic graph theory. To address the challenges of a complex and dynamic environment, an adaptive sliding mode control (SMC)-based consensus protocol is proposed. The closed loop stability analysis is established through Lyapunov theory. Findings: The efficacy of the discussed robust consensus controller is analyzed through numerical simulations. Further, the quantitative analysis using Monte-Carlo simulations validates performance of the proposed robust consensus protocol. The presented consensus protocol can be easily implementable as robust flight controller for swarm of UAVs. Also, as the consensus theory is based on the algebraic graph theory, the proposed design is scalable for a large number of UAVs in swarm formation. Originality/value: The proposed adaptive SMC achieves robust consensus of longitudinal dynamics states between all the UAVs by mitigating the effects of wind gust disturbances. Also, the adaptive SMC offers chattering-free control efforts. [ABSTRACT FROM AUTHOR]

Alkali atom-doped hexalithioborazine (B3N3Li6-M) as a novel class of super-alkali complex has been investigated for their exceptionally high first-order and second-order electrical responsive properties. The stability of resulting complexes, B3N3Li6-M (M = Li, Na, and K), is confirmed by the ADMP simulation and the negative values of thermodynamic parameters such as binding energy (∆Eb) and Gibbs free energy (∆G). The relationship between aromaticity (NICS) and first hyperpolarizability of B3N3Li6-M follows linear relationship. Diffuse electron cloud around the central ring and doped alkali metal in the HOMO of B3N3Li6-M complexes has been attributed to the charge transfer from peripheral Li to the dopant metal (M) atom. The dipole moment of B3N3Li6-M varies between 0.507 D (M = Na) and 1.608 D (M = Li) due to charge transfer in these complexes. The mean polarizabilities (αav) of B3N3Li6-M ranging from 573.08 to 1598.86 a.u are observed. Exceptionally high value of second-order NLO parameter (βav = 5.133 × 105 a.u and βHRS = 2.166 × 106 a.u) are observed in case of Li-doped B3N3Li6 in this series. Thus, the first hyperpolarizability (βav and βHRS) values of the complexes produced by the interactions between alkali metal atoms (M) and B3N3Li6 are strong enough to demonstrate as potential second-order NLO materials. [ABSTRACT FROM AUTHOR]

A designed aggregation-induced emission enhancement (AIEE) active fluorescence probe 2,3-Bis-[(2-hydroxy-napthalen-1-ylmethylene)-amino]-but-2-enedinitrile (L) was synthesized via one step condensation method. The probe shows swift sensitivity and selectivity toward Al3+over other relevant metal ions and also exhibits significant AIEE phenomena in methanol/water mixture. Significant enhancement of fluorescence intensity is triggered via chelation-enhanced fluorescence through complex (Al3+-L) formation. A 2:1 metal to ligand ratio is observed from Job's plot based on UV − Vis absorption titration and detection limit (LOD) is found as low as 31.14 nM. Moreover, 1H NMR titrations and fluorescence reversibility by adding Al3+ and EDTA sequentially had been performed to establish the binding site of sensor complex (Al3+-L). Time-resolved photoluminescence, dynamic light scattering, optical microscopy, and on-site visualization studies have been performed to understand the AIEE mechanism of L in different volume percentage of water and methanol mixture. An INHIBIT molecular logic gate has been constructed utilizing the fluorescence behavior of the probe, L in presence of Al3+ and strong chelating ligand EDTA. [ABSTRACT FROM AUTHOR]

Fluorescent chemosensor, 3-(Anthracen-2-yliminomethyl)-benzene-1,2-diol (ANB) has been synthesized by one-step condensation of 2-aminoanthracene and 2,3-dihydroxybenzaldehyde and characterized using 1H-NMR, FT-IR and Mass spectroscopic techniques. The probe ANB was found to be an efficient 'turn-on' fluorescence chemosensor for the selective detection of Al3+ ion over other metal ions in an aqueous solution. The chemosensor exhibits ~ 27-fold enhancement of emission intensity in presence of Al3+ ion. Fluorescence quantum values for ANB and (Al3+-ANB)-complex are 0.004 and 0.097, respectively. In addition, the binding constant and the limit of detection were found to be 1.22 × 104 M−1 and 0.391 µM, respectively. The chemosensor ANB binds to Al3+ ions in 2:1 stoichiometric ratio which was supported by Job's plot, 1H-NMR titration and florescence titration. Fluorescence reversibility of the sensor complex was well established by adding EDTA in the same condition and a molecular INHIBIT logic gate was fabricated using this reversible nature of the sensor complex. Additionally, the chemosensor ANB shows a novel aggregation-induced enhanced emission phenomenon, where the aggregate hydrosol of ANB shows enhance emission intensity. [ABSTRACT FROM AUTHOR]

A multi responsive fluorescent probe, N',2-bis(E-4-(diethylamino)-2-hydroxybenzylidene)hydrazine-1-carbothiohydrazideV(H2L) has been synthesized through one step condensation method. Probe, H2L shows 'turn-on' dual sensing properties towards Cd2+ and H2AsO4− at two distinct wavelength. The probe (H2L) is spectroscopically characterized and the chemo-sensing mechanism has been demonstrated through 1H NMR, absorption, steady state and time resolved emission study. The most promising advantage of the probe is its application in the one-pot detection of Cd2+ (λem = 462 nm) and H2AsO4−(λem = 492 nm) where intense emission appears at two different wavelengths and the observed limit of detection (LOD) of H2L towards Cd2+ and H2AsO4− are 2.67 × 10–8 M and 5.14 × 10–6 M respectively. Further the 'turn-on' emission property of H2L towards Cd2+ is applied to construct INHIBIT logic gate. [ABSTRACT FROM AUTHOR]

The contrast of the second-order nonlinear optical response between the enol (anti and syn) and keto tautomeric equilibrium of 7-Phenyl-7H-benzo[1,2-b;4,5-b']difuran-2,3,6-trione (PBDT) with donor/acceptor substitution at the para position of phenyl group have been computed involving electron correlation, frequency dispersion, and solvent polarity effects. The Hyper Rayleigh Scattering (HRS) first-hyperpolarisability contrast between the enol and keto forms for PBDT and Nitro-substituted PBDT is 3.5 and 2.8, respectively. However, in NMe2-substituted PBDT, a large contrast (~12 times) of HRS first hyper-polarisability between enol (anti and syn) and keto form is observed. Present study reveals that electron donor group (-NMe2) in PBDT plays a pivotal role for obtaining very high contrast in the first hyper-polarisability (ßHRS and ßvec) values between the enol and keto forms compare to the electron acceptor (-NO2) group substitution at the same position. The solvent effect also plays a significant role in further improving the first hyper-polarisability value and its switching behaviour between the enol and keto forms of NMe2-PBDT. NLO switching contrast between the enol and keto forms of donor/acceptor substituted PBDT is also explained using the electronic features including UV-Vis absorption spectra, HOMO-LUMOelectron densities, optical energy gaps, charge transfer contribution etc. [ABSTRACT FROM AUTHOR]

A Fluorescent chemosensor based on pyrene scaffold, 5-diethylamino-2-(pyren-1-yliminomethyl)-phenol (PDS) is synthesized using condensation method. It displays novel aggregation-induced emission (AIE) phenomena in its aggregated/solid state. The AIE characteristic of PDS is studied in CH3CN/H2O mixtures at different volume percentage of water and morphology of the aggregated particles are investigated by DLS and optical fluorescence microscopic study. The probe is aggregated into ordered one-dimensional (1-D) rod like microcrystals and exhibit high efficiency of solid-state emission with green colour. By taking advantage of its interesting AIE feature, the aggregated hydrosol has been utilized as 'off–on' type fluorescence switching chemosensor with superb selectivity and sensitivity towards Cu2+ions and the limit of detection (LOD) was calculated as low as 6.3 µM. A high Stern–Volmer quenching constant was estimated to be 2.88 × 105 M−1. The proposed chemosensor with AIE feature reveals a prospective view for the on-site visual recognition of Cu2+ ions in fluorescent paper strips and the synthesized probe is also exploited to find out the concentration of Cu2+ions in real water samples. [ABSTRACT FROM AUTHOR]

Potential energy (PE) curves along the proton transfer co-ordinate of ground and excited states of 9-Hydroxy-phenalen-1-one (9HPO) and 6-Hydroxy-benzo[de]anthracen-7-one (6HBAO) have been studied using DFT-CAM-B3LYP/6-311G(d,p) and TD-DFT-CAM-B3LYP/6-31G(d) level of theory, respectively. The choice of these two molecules is based on their symmetric and asymmetric nature for their intramolecular H-bonded six-membered ring systems. Ground and excited states of PE calculations show that due to lower potential energy barrier, 9-Hydroxy-phenalen-1-one (9HPO) and 6-Hydroxy-benzo[de]anthracen-7-one (6HBAO) can be in equilibrium with their enol and keto tautomeric forms. Computed values of global reactivity descriptors, that is, average polarisability (αav) and chemical hardness (η) along the proton transfer co-ordinate of both the molecules are very small although their variations conform with their respective optimum principles. Inspired by the significant variation of the first hyperpolarisabilty along the proton transfer co-ordinate of both the compounds, it is concluded that the first hyperpolarisability can serve as a better parameter to identify enol or keto tautomeric forms in enol keto equilibrium. The variation of average first hyper polarisability (βav) along the proton transfer co-ordinate follows the optical gap rule in both the molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Rhodamine-Quinoline based probe has been synthesized. • It has been used to detect trace amount of Al3+, Cr3+ and HSO 4 − ions in water. • DFT & TD-DFT calculation were done to justify the experimental results. • Turn-on emission property of the probe is utilized to fabricate molecular INHIBIT logic gate. • Cytotoxicity and cell imaging on TPC-1 & HtH-7 cell lines. A designed Rhodamine-B-quinoline based Schiff base chemosensor (RhBQ) has been synthesized and characterized using various spectroscopic techniques. It shows 'turn on' fluorescence emission and also colorimetric sensitivity and selectivity towards trivalent metal ions (Al3+ and Cr3+) and anion (HSO 4 −) present in aqueous medium. Stoichiometry of both metal (Al3+ & Cr3+) - RhBQ complexes are found to be 1:1 using Job's plot. A notable enhancement in emission intensity for RhBQ-Al3+ (∼341 fold), RhBQ-Cr3+ (∼292 fold), and RhBQ-HSO 4 − (∼136 fold) complexes compare to RhBQ are observed. Sensing mechanism i.e. opening of spirolactam ring of RhBQ has been confirmed through various spectroscopic techniques such as; 1H NMR, 13C NMR, ESI-MS, TRPL, FT-IR, and DFT based computational study. The limit of detection (LOD) for Al3+, Cr3+, and HSO 4 − are found to be 2.2 × 10−8 M, 2.12 × 10−8 M and 8.63 × 10−7 M respectively. An advanced level 3 input OR–INHIBIT logic gate are constructed using chelating ligand EDTA. For onsite detection, TLC paper strip spot of the probe, RhBQ is prepared and the detection of Al3+ in few antacid drug are presented. In addition, cell-imaging analysis of Al3+, Cr3+, and HSO 4 − ions in the Human papillary thyroid carcinoma cell line (TPC-1) & Human anaplastic thyroid cancer cell lines (HtH-7) are presented and shows promising concentration and time-dependent detection results. [ABSTRACT FROM AUTHOR]

The original article can be found online at https://doi.org/10.1007/s43630-023-00392-7. The correct name is given below: Rodrigo Ramirez-Tagle Universidad de las Américas, Facultad de Salud y Ciencias Sociales, Santiago, Chile The original article has been corrected. [Extracted from the article]

• A novel Phenolphthalein based probe has been synthesized. • It has been used to detect trace amount of Zn2+ and Al3+ ions in water. • Turn-on emission property of the probe is utilized to fabricate molecular INHIBIT logic gate. • It also displays the novel AIE phenomenon. A phenolphthalein based fluorescent probe, 3, 3-Bis-[4-hydroxy-3-(pyridine-2-yliminomethyl)-phenyl]-3H-isobenzofu ran-1-one (PHPA), has been synthesized. It exhibits high sensitivity and selectivity towards Zn2+ and Al3+over other relevant water soluble metal ions and also display novel aggregation-induced emission enhancement (AIEE) characteristics. Both complexes followed 2:1 metal to ligand stoichiometry calculated from Job's plot. A significant fluorescence enhancement with a turn-on ratio of ∼94-fold was triggered via chelation-enhanced fluorescence through sensor complex (Zn2+-PHPA) and∼245-fold increase for sensor complex Al3+-PHPA. In addition, the binding sites of both sensor complexes (PHPA-Zn2+ & PHPA-Al3+) have been confirmed through 1H NMR, 13C NMR, FT-IR and ESI-MS spectroscopy. The detection limits is found to be 8.5 × 10−8 M for complex PHPA-Zn2+ and 1.88 × 10−7 M for complex PHPA-Al3+, respectively. The reversible detection of Zn2+ and Al3+ complexes in methanol are also ascertained in the presence of Na 2 EDTA, enabling the construction of a molecular Logic gate. An advanced-level NOT-AND-OR logic gate has been constructed from a different chemical combinational input and emission output. Human serum albumin (HSA) binding studies were performed by various spectroscopic methods to expound possible bioactivity of PHPA. Interestingly; the AIEE properties of PHPA may advance its impact as studied in methanol-water mixtures with high water contents. To gain the knowledge into the AIEE mechanism of the PHPA, the size and growth process of particles in different volume percentage of water and methanol mixture were studied using time-resolved photoluminescence, dynamic light scattering, and optical microscopic image. The probe PHPA has also been used to detect intracellular Zn2+ ion in A549 cells. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A multianalyte selective fluorescent probe derived from rhodamine and phenolphthalein is synthesized. • It showed highly selective and sensitive response towards Cu2+, Fe3+ colorimetrically and Al3+, Cr3+ fluorimetrically. • Detection limits for Cu2+, Fe3+, Al3+ and Cr3+ are 1.21 µM, 1.75 µM, 2.27 µM, and 1.29 µM, respectively. • Test paper strips of the probe were prepared for rapid and selective detection for four analytes. • It is also used as a bio-imaging fluorescent probe against A549 cancer cell line. In this study, a novel rhodamine-phenolphthalein derivative (RBPF) was designed, synthesized, and characterized. RBPF exhibited the selective and sensitive colorimetric detection of Cu2+ and Fe3+ and fluorometric detection of Al3+ and Cr3+, thus functioning as a multiple-channel probe in MeOH-H 2 O (v/v = 9/1, 5 µM HEPES, pH 7.2) in the presence of other cations. A strong enhancement of the absorbance at around 555 nm was observed for the four mentioned cations. In contrast, in the presence of Al3+ and Cr3+, emissions were intensified within the red region of the spectra (583 and 586 nm, respectively). The RBPF sensor was found to bind to the metal ions at a 1:2 stoichiometric ratio. The proposed mechanism for the observed sensing behavior is the opening of the spirolactam ring of the rhodamine core in the presence of the four mentioned metal ions. The detection limits for Cu2+, Fe3+, Al3+, and Cr3+ were calculated to be 1.21 µM, 1.75 µM, 2.27 µM, and 1.29 µM, respectively. To test the practical use of the probe, TLC-based paper strips were fabricated. In addition, cell-imaging analysis of Al3+ and Cr3+ ions in the A549 cancer cell line produced promising concentration and time-dependent detection results. [ABSTRACT FROM AUTHOR]

• A phenolphthalein-aminophenol (PFAP)-based chemosensor for Al3+ was synthesized. • PFAP showed a LOD of 1.5 µM and a fast response time of 10 s. • PFAP was used to detect Al3+ in the intracellular region of the A549 cancer cells. Monitoring of excess Al3+ and its selective detection in biological and environmental samples are important tasks for researcher due to its harmful effects. Herein, we present a phenolphthalein-aminophenol derived sensor (PFAP) for the selective fluorescent response of Al3+ in an "OFF-ON" mode over a pool of analytes including eighteen cations with striking greenish emission. It has a prominent limit of detection (LOD) value (1.5 µM), fast response time (10 s) for Al3+ detection. The complexation properties of PFAP with Al3+ ions were clarified by UV–vis, 1H & 13C NMR, HRMS, and FTIR spectroscopic experiments. The recognition mechanism of PFAP for Al3+working with chelation enhanced fluorescence (CHEF) and is verified with two model compounds PF and PFAN in the light of UV–vis, PL, TRPL, and NMR experiment. To check its applicability, easily prepared test paper and TLC strip of PFAP was produced for rapid and selective onsite detection of Al3+ ions. Bio-imaging application of PFAP in human lung cancer cell lines A549 demonstrated excellent results with negligible cytotoxicity and as an excellent marker to detect traces of Al3+ ion in a time-dependent as well as concentration-dependent manner. Actual sample analysis for Al3+ with the probe PFAP produces fruitful result. [Display omitted] [ABSTRACT FROM AUTHOR]