Free Rotation Research Articles

Attachment of -tBu groups to aza-BODIPY core at 3,5-sites with ultra-large Stokes shift to enhance photothermal therapy through apoptosis mechanism.

By the introduction of the −tBu groups into aza-BODIPY core, di-tert-butyl-substituted aza-BODIPYs at 3,5-sites (tBuazaBDPs) were prepared for the first time. Based on the X-ray analysis of CN-tBuazaBDP, this molecular structure is twisted. Near-infrared dye SMe-tBuazaBDP has the ultra-large Stokes shift (152 ​nm) in aza-BODIPY system, combining with the twisted intramolecular charge transfer and the free rotation of the −tBu groups at 3,5-sites. Although the barrier-free rotors of the distal −tBu groups in SMe-tBuazaBDP result in low fluorescence quantum yield, the photothermal conversion efficiency is markedly enhanced. SMe-tBuazaBDP nanoparticles with low power laser irradiation were proven to block cancer cell cycle, inhibit cancer cell proliferation, and induce cancer cell apoptosis in photothermal therapy (PTT). The strategy of “direct attachment of −tBu groups to aza-BODIPY core” gives a new design platform for a photothermal therapy agent.

Прикладные задачи статического поперечного изгиба и устойчивости листа графена

In the paper, based on the previously developed continuous moment-membrane theory which describes the deformations of two-dimensional nanomaterials (including graphene), two applied problems are considered for a rectangular graphene sheet: 1) the problem of the static transverse bend, 2) the problem of stability of its initial compressed state. The functions of displacement and free rotations are determined for the problem of the static transverse bend of the graphene sheet. In the case of the problem of stability of the initially compressed state of a graphene sheet, the critical load is determined.

Design and Fabrication of Soft 3D Printed Sensors and Performance Analysis of the Soft Sensors in a C-leg as Sensing Element

In soft robotics, a recent challenge is to decrease the number of rigid components used tocreate entirely soft robots. A common rigid component used in soft robots is the rigid encoder, which should be replaced with a soft counterpart if possible. In this work, we de-sign and manufacture a soft sensor, which is embedded into a C-shaped leg of a soft, legged, miniature robot. Our main goal is to show that we can embed a soft sensor into and receive contact feedback from a soft C-shaped leg of our soft miniature quadruped. We test various sensor parameters using custom test setups to analyze the soft sensor performance. Our soft sensor design is iterated by experimentally investigating several sensor shape options. For the C-leg of the soft miniature quadruped, optimal sensor geometry and position for the sensor implementation are found from a discrete design space as the outcome of this work. We received feedback from the soft sensor and compared commercial encoder data to the soft sensor embedded C-leg data. We managed to detect the rotation speed of the C-leg with the accuracy of 87.5% on a treadmill and with the accuracy of %86.7 under free rotation of the C-leg. However, if connection loss occurs in the miniature slipring mechanism, the error percentage in estimating the rotational speed increases significantly.

Mitochondria targeted dual-fluorescent probe for bio-imaging viscosity and F− with different fluorescence signals

The F− ion and viscosity both affect the physiological state of mitochondria and to the best of our knowledge no fluorescent probe is reported for the dual detection of mitochondrial viscosity and F− ion through different signals. DMAS-Si is weakly red fluorescent due to free intramolecular rotation between dimethylaminophenyl and pyridinium moieties and PET from silyloxy to the pyridinium moiety. In viscous medium (glycerol 90 %), the rotation is restricted and 18-fold increase in red-fluorescence (λem 637 nm) is observed. On reaction with F− ion, the desilylations followed by release of quinone-methide from DMAS-Si gives intense green fluorescence (λem 515 nm) due to formation of DMAS. DMAS-Si can detect as low as 50 nM F−. DMAS-Si shows good permeability to HeLa cells and preferably targets mitochondria. It has been used for imaging of increased viscosity in mitochondria of HeLa cells in the presence of nystatin through red fluorescence and exogenous F− ion by appearance of green fluorescence.

An Incidental Discovery of a Serious Complication

An Incidental Discovery of a Serious Complication

Versatility of unilateral propeller groin flap for coverage of large scrotal defects and its impact on testicular function

BackgroundThere are many options for scrotal reconstruction, each having its own benefits and drawbacks. In the last years, the introduction of the propeller flaps gained great popularity, while the use of groin flap as propeller in scrotal reconstruction remains anecdotal, with only a few cases reported in the literature.ObjectivesIn this research, we study the versatility of unilateral propeller groin flaps in the reconstruction of large scrotal defects.Patients and MethodsThis study was done on 10 patients with scrotal defects who were admitted to the plastic unit of the general surgery department at Benha University Hospital from 2019 to 2021 for scrotal reconstruction.ResultsAll surgeries were successful with a mean operative time of 103.5 min, ranging from 90 to 130 min. All flaps survived well with no flap necrosis, and only one case showed flap congestion. Donor site healed well with the scar hidden in a natural crease, with no affection on the testicular functions.ConclusionsThe use of groin flap as a propeller allows for free movement and rotation of the flap, which allows for better coverage of a large scrotal defect with good vascularity, lesser complications, no need for further operations to separate the pedicle, and the lowest donor site morbidity.Level of evidenceLevel IV, therapeutic study

New ruthenium complexes containing salicylic acid and derivatives induce triple-negative tumor cell death via the intrinsic apoptotic pathway

In this work we present the synthesis and characterization of six new ruthenium compounds with general formulae [Ru(L)(dppb)(bipy)]PF6 and [Ru(L)(dppe)2]PF6 where L = salicylic acid (Sal), 4-aminosalicylic acid (AmSal) or 2,4-dihydroxybenzoic acid (DiSal), dppb = 1,4-bis(diphenylphosphino)butane, dppe = 1,2-bis(diphenylphosphino)ethane and bipy = 2,2′-bipyridine. The complexes were characterized by elemental analysis, molar conductivity, cyclic voltammetry, NMR, UV–vis and IR spectroscopies, and two by X-ray crystallography. The 31P{1H} NMR spectra of the complexes with the general formula [Ru(L)(dppe)2]PF6 showed that the phosphorus signals are solvent-dependent. Aprotic solvents, which form strong hydrogen bonds with the complexes, inhibit the free rotation of the salicylic acid-based, modifying the diphosphine cone angles, leading to distortion of the phosphorus signals in the NMR spectra. The cytotoxicity of the complexes was evaluated in MCF-7, MDA-MB-231, SKBR3 human breast tumor cells, and MCF-10 non-tumor cell lines. The complexes with the structural formula [Ru(L)(dppe)2]PF6 were the most cytotoxic, and the complex [Ru(AmSal)(dppe)2]PF6 with L = 4-aminosalicylic acid ligand was the most selective for the MDA-MB-231 cell line. This complex interacts with the transferrin and induces apoptosis through the intrinsic pathway, as demonstrated by increased levels of proteins involved in apoptotic cell death.

Development of novel near-infrared GFP chromophore-based fluorescent probes for imaging of amyloid-β plaque and viscosity

Alzheimer's disease (AD) is closely associated with abnormal deposition of amyloid β (Aβ) peptides and formation of plaques. Green fluorescent protein (GFP) chromophores with a high-quality biomimetic fluorophore skeleton, have been extensively explored in biomedical diagnosis. However, its applications in intact animals were highly limited due to their short excitations and emissions owing to the absorption, scattering and auto-fluorescence by endogenous substances. In this work, through π-extension of the double bond bridge between the aromatic and imidazolidinone rings of the GFP chromophore, the emission of CX1 reached NIR window (over 702 nm) and what’s more interesting, the affinity of CX1 with Aβ aggregates was obviously improved. CX1 effectively avoided the limit in vivo imaging due to short excitation and emission and showed higher selectivity and signal-to-noise ratio towards Aβ plaques. In the hydrophobic cavity of Aβ aggregates or increased viscosity, the free rotation of CX1 was efficiently limited due to inhibition of twisted intramolecular charge transfer and thus the fluorescence emission exhibited a significant increase. Furthermore, CX1 can clearly image Aβ aggregates in the brain of transgenic mice and viscosity in living cells, which could serve as an effective tool for monitoring the pathological process of AD.

Design of a More Efficient Rotating-EM Energy Floor with Lead-Screw and Clutch Mechanism

There is an interest in harvesting energy from people’s footsteps in crowded areas to power smart electronic devices with low consumption. The average power consumption of these devices is approximately 10 μW. The energy from our footsteps is green and free, because walking is a routine activity in everyday life. The energy floor is one of the most efficient pieces of equipment in vibration-based energy harvesting. The paper aims to improve the previous design of the energy floor—called Genpath—which uses a rotational electromagnetic (EM) technique to generate electricity from human footsteps. The design consists of two main parts of (1) the EM generator, including the lead-screw mechanism for translation-to-rotation conversion, and (2) the Power Management and Storage (PMS) circuit. The improvement was focused on the part of the EM generator. A thorough investigation of the design components reveals that the EM generator shaft in the previous Genpath design cannot continuously rotate when the floor-tile reaches the bottom end, resulting in no energy gain. Therefore, a one-way clutch is implemented to the system to disengage the generator shaft from the lead-screw motion when the floor-tile reaches the allowable displacement. During the disengagement, the EM generator shaft still proceeds with a free rotation and could generate more power. In our analysis, the dynamic model of the electro-mechanical systems with the one-way clutch was successfully developed and used to predict the energy performances of the VEH floors and fine-tune the design parameters. The analytical result is shown that the spring stiffness mainly affects the force transmitted to the EM generator, and then the induced voltage and power of the generator, thus, the value of the stiffness is one of the critical design parameters to optimize. Finally, the new prototype consisting of 12-V-DC generator, mechanisms of lead-screw and clutch, as well as coil springs with the optimal stiffness of 1700 N/m was built and tested. The average energy produced by the new prototype is 3637 mJ (or average power of 3219 mW), per footstep which is 2935 mJ greater than that of the previous design. Moreover, to raise the social awareness about energy usage, the sets of Genpath have been used to organize an exhibition, “Genpath Empower our Journey”. The people who stroll forward on the paths can realize how much energy they gain from their footsteps.

Chemical reaction thresholds according to classical-limit quantum dynamics.

Classical-limit quantum dynamics is used to explain the origin of the quantum thresholds of chemical reactions from their classical dynamics when these are vibrationally nonadiabatic across the interaction region. This study is performed within the framework of an elementary model of chemical reaction that mimics the passage from the free rotation of the reagents to the bending vibration at the transition state to the free rotation of the products.

Nonlinear dynamic model for the free rotor of the swash plate-rotating hydraulic transformer

Hydraulic transformer (HT) is an energy conservation component used in the common pressure rail system and achieves an excellent energy-saving effect in construction machinery and vehicle transmission. This paper reports a complete nonlinear dynamic model and validation for the free rotor in a swash plate-rotating hydraulic transformer (SPRHT), accounting for various time-varying effects. A parameter characterization model for the oil properties considering gas-liquid phase and pressure is described. Based on the lumped element method, the fluid dynamic model for the working chambers is established, taking account of the variation of the control volume/flow area in the working chambers and leakage. The dynamic model for the free rotor is constructed, accounting for the piston distribution and nonlinear friction. Combining the above models, the speed of the free rotor is solved by the Runge-Kutta method. The SPRHT is simulated in the AMESim. Particularly, a prototype is developed, and the dynamic test is carried out. Then the potential of the nonlinear model for the free rotor is verified. The proposed nonlinear dynamic model of the free rotor can be used for the dynamic behavior analysis and energy efficiency optimization of the HT.

Experimental and Numerical Investigations on the Moment Capacity and Stability of Z‐shaped Steel Piles

AbstractHarbour structures like quay walls or construction pit walls in civil engineering are often built up with steel sheet piles. Aside of U‐steel sheet piles also Z‐shaped piles with interlocks are widely used in such structures. The pressure on costs and efficiency and the competition in this field lead to the necessity of increased efficiency in design. To benefit from the potentials in the bending moment capacity of semi‐compact Z‐shaped steel sheet piles forming the infills of combined walls, four‐point‐bending tests were carried out by the Institute of Structural Design at the Materials Testing Institute in Stuttgart in 2019. A FE‐model was validated by back‐calculating the tests, followed by an extensive parametric study (GMNIA) with different Z‐piles. Among others the different geometries, which lead to different b/t‐ratios and the steel grade were varied leading to a different compression flange slenderness. In addition, the lock state was varied to investigate the impact on the bending moment capacity as: Free lock rotation, crimped interlocks with different crimping densities and fully welded over the entire length. Three resistance models were investigated and evaluated for further development of Eurocode 3 Part 5. The FE model was simplified and further developed for stability analyses. This was followed by a parametric study aimed to investigate the stability of Z‐shaped steel sheet piles under axial loads.

A robot hand with free-rotating grips for switching three different grasping modes

ABSTRACT The automation of the display and disposal of products on shelves has attracted widespread attention because it is the most time-consuming task in convenience store operations. However, robots find it difficult to perform store operations because products vary in shapes and sizes and must be displayed in specific positions on narrow shelves. In this study, we developed a robot hand that can grasp various products and easily change its posture. The hand has two free rotating grips that allows the robot to change position between the following three grasping modes: (i) grasp mode: prevents the free rotation of an object, (ii) rotation mode: changes the posture of the object due to its weight, and (iii) scoop mode: allows the robot to grasp a flat object. A performance evaluation experiment was conducted using the robot hand. Subsequently, three results were obtained. First, the robot hand successfully grabbed a cork block, a rice ball, and a sandwich in the grasp and rotation mode, and the gripper behavior changed depending on the grasping mode. Second, the robot hand successfully grasped a lunch box in the scoop mode. Third, the robot hand switched from the grasp to the rotation mode while grasping the object. These results indicate that the hand can change its posture owing to gravity at any time.

Highly Efficient Aggregation-Induced Electrochemiluminescence of Al(III)-Cbatpy Metal-Organic Gels Obtained by Ultrarapid Self-Assembly for a Biosensing Application.

Aggregation-induced electrochemiluminescence (AIECL) has attracted extensive interest due to the significant increase in ECL response by restricting free intramolecular rotation and torsion, but traditional AIECL emitters suffer from limited ECL efficiency, high cost, and complex synthetic steps, dramatically limiting their applications. Herein, novel Al(III)-Cbatpy metal-organic gels (Al(III)-Cbatpy-MOGs) with nanofiber morphology and ultrarapid coordination of Al3+ and 4'-carboxylic acid-2,2':6',2″-terpyridine (Cbatpy) are developed, which demonstrates an excellent AIECL enhancement behavior far beyond that reported in ECL supramolecular gels. In view of the strong affinity of N and O atoms in Cbatpy toward Al3+, Al(III)-Cbatpy-MOGs with high viscosity and stability can be assembled in one step within about 15 s, easily conquering the main predicaments of current AIECL emitters: complicated synthesis steps and poor film formation. Impressively, the ECL efficiency of Al(III)-Cbatpy-MOGs with superemission is about 20 times higher than that of individual Cbatpy molecules, which is attributed to the aggregation of the organic ligand Cbatpy restricting intramolecular rotation and torsion to reduce nonradiative relaxation. Furthermore, compared with traditional metal complexes, Al(III)-Cbatpy-MOGs show the benefits of remarkable biocompatibility and low cost without the involvement of any organic solvents, noble metals, and rare metals. As proof, a "signal-off" sensing platform based on an Al(III)-Cbatpy-MOGs/S2O82- system was constructed for the sensitive detection of dopamine (DA) with a low detection limit of 0.34 nM. This strategy provides a novel method to prepare cheap metal-organic gels as a highly efficient AIECL emitter, which is promising as a luminescent molecular device and biosensor for clinical diagnostic applications.

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ ЕЛЕКТРИЧНОЇ МАШИНИ З ТРИСТУПЕНЕВИМ ГІРОСТАБІЛІЗОВАНИМ РОТОРОМ

A retrospective review of the development of the theory and practical structures of electric machines with a three-degree-of-freedom rotor (EMTR) at the Institute of Electrodynamics of the National Academy of Sciences of Ukraine. The applications of EMTR in surveillance, tracking and stabilization systems on moving objects are listed. The relevance of the development of such machines is shown. The disadvantages of the classical mathematical model of EMTR are noted and the need to develop a refined mathematical model due to the need to develop new technology, the emergence of new materials and electronic components, as well as the growth of computing capabilities. The two main known structures of EMTR are described and the advantages of the perspective structure chosen as the basic one are listed. The model of static three-dimensional magnetic field of EMTP and the associated dynamic model in the COMSOL Multiphisics environment are substantiated and constructed for the basic structure of EMTR. The connection between the magnetostatic problem and the rotor motion dynamics problem is ensured by the fact that the data of the calculated instantaneous characteristics are transmitted in the form of approximated dependences to the dynamic problem. In the mode of free rotation without losses, the dependences of the precession angle on time, amplitude and phase of the sinusoidal current of the control winding are calculated. High accuracy of observance of the direction of precession of the axis of the rotor at observance of the corresponding initial phase of sinusoidal current of a control winding is noted. The influence of rotation windings on the moment created by the control winding is investigated. References 3, figures 8.

ПУТИ СНИЖЕНИЯ ИЗНОСА ГРЕБНЕЙ КОЛЕСНЫХ ПАР В ТЕЛЕЖКАХ ГРУЗОВЫХ ВАГОНОВ

The study objective is to reduce the number of cases of current uncoupling repairs and operational costs associated with defects in wheel flanges of freight cars in conditions of increasing linear and axial loads and speeds. The paper is devoted to solving the problem of improving the interaction of the friction-mechanical system "wheel-rail" in curved sections of the track by reducing the anti-torque in the places of the supports of the car body on bogies. Computational and experimental research methods are used. The novelty of the work is that rational friction pairs in the unit of center plate – female center plate, friction and strength characteristics of composite polymer materials for installation in the support units of the car are experimentally determined; there are also calculated the moments of resistance forces to the bogie turning from the real values of the friction factors for different variants of supporting the car body, simulating the passage of transition and circular curves. As a result, the following is found: the lowest friction factor of 0.11 is shown by a pair of friction – metal-glass-filled polyamide 6, which reduces the moment of resistance to rotation when fully supported by a female center plate by 2.91 times, and when implemented on a side bearing, the total anti-torque also decreases by 2.91 times; the wearing of glass–filled polyamides by 2.5 two times lower than for other modifications, and hardness increases with an increase of glass fiber in the structure. This leads to making the following conclusions: a rational pair of friction in the unit of center plate – female center plate is metal - glass–filled polyamide 6; to reduce the wear of flanges in curved sections of the track, it is advisable to implement a simultaneous reduction in friction factor in the areas of female centre plate and side bearings for free rotation of the bogie in curves; Currently developed composite polymer materials, which simultaneously have high strength and anti-friction properties (polyamides modified with fiber glass, molybdenum disulfide, fullerene fillers), can have a positive effect on solving the problem of wear of wheel flanges.

Concentric-Coil Hybrid IPT System With Improved Tolerance to Coupling and Load Variations

Hybrid tuning topologies had been proposed with polarized magnetic couplers to improve the alignment tolerance of inductive power transfer (IPT) systems. However, the technologies are mainly applicable to IPT systems with directional coupling and relatively low inductance variations. This article proposes an IPT system with a dual-concentric-coil transmitting (Tx) and single-coil receiving (Rx) coupling configuration with hybrid tuning networks for improving the output voltage characteristics over a wide range of coupling and load variations. The concentric coils allow free rotation while integrated hybrid tuning networks help reduce the output voltage fluctuation under varying horizontal and spatial misalignments. A design procedure is proposed using finite-element method (FEM) and circuit simulations to select tuning parameters accounting for varying self and mutual inductances. Simulation and experimental results show that the self-inductance of the proposed coil can change by 48%, and the coupling coefficient varies between 0.43 and 0.74 under misalignments, leading to over 100% change of the unregulated output voltage if the system is series–series tuned. In contrast, a laboratory prototype of the proposed system demonstrates a stable output voltage within ±9% of fluctuation around 13.25 VDC.

Quantum mechanical analysis of the geared rotation of a model molecule

The quantum chemical calculations of a model molecule for the molecular spur gear at the M06-2X/6-31++G(d,p) level of theory have been carried out to obtain the potential energy surface for the two-dimensional internal rotations. The energy levels, the wavefunctions and the time evolution of the wave packets have been calculated to evaluate the performance of the molecule as a gear. It was confirmed that the geared rotation of the two rotors is a hindered rotation, not a free rotation. It has been also revealed that the molecule can undergo the “slippage” of the gear mesh because of the tunneling.

Fluid Layered Ferroelectrics with Global C∞v Symmetry.

Ferroelectricity in fluid materials, which allows free rotation of molecules, is an unusual phenomenon raising cutting‐edge questions in science. Conventional ferroelectric liquid crystals have been found in phases with low symmetry that permit the presence of spontaneous polarization. Recently, the discovery of ferroelectricity with high symmetry in the nematic phase has attracted considerable attention. However, the physical mechanism and molecular origin of ferroelectricity are poorly understood and a large domain of macroscopically oriented spontaneous polarization is difficult to fabricate in the ferroelectric nematic phase. This study reports new fluid layered ferroelectrics with the C∞v symmetry in which nearly complete orientation of the spontaneous polarization remains stable under zero electric field without any orientation treatment. These ferroelectrics are obtained by simplifying the molecular structure of a compound with a known ferroelectric nematic phase, although the simplification reduced the dipole moment. The results provide useful insights into the mechanism of ferroelectricity due to dipole–dipole interactions in molecular assemblies. The new ferroelectric materials are promising for a wide range of applications as soft ferroelectrics.

Axial Chirality and Antiviral Activity Evaluation of Arylnaphthalene Lignan Glycosides from Justicia procumbens

AbstractOne of the structural uniqueness of arylnaphthalene lignans (ANLs) is their potential atropoisomerism, which may result in bioactivity discrepancy. However, the stable ANL atropisomers rarely exist in nature. In the course of our phytochemical study of Justicia procumbens, we isolated nine ANL glycosides (1–9) with four of them (1–4) being identified as new stable atropisomers. Their absolute configurations were determined based on the analysis of the circular dichroism (CD) and electronic circular dichroism (ECD) data. The ANL compounds were evaluated for their antiviral potential as entry inhibitors against the infections of H5N1 influenza virus, vesicular stomatitis virus (VSV) and severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) with 5 being the most potent one with IC50 values ranging from 0.0063–1.13 μM. The atropisomers did not display significant antiviral activity, indicating that a free rotation of the biphenyl aryl‐aryl bond could play a significant role in the antiviral activity of ANL compounds.