Ladder Type Research Articles

Ladder-type π-conjugated metallophthalocyanine covalent organic frameworks with boosted oxygen reduction reaction activity and durability for zinc-air batteries

π-Conjugated two-dimensional covalent organic frameworks (COFs) represent a family of rising oxygen electrocatalysts due to their controllable architectures, outstanding electrical conductivity and highly exposed molecular active sites. Herein, we report a novel ladder type π-conjugated two-dimensional benzoimidazobenzophenanthroline-linked iron-phthalocyanine COF (denoted as FePc-BBL COF) via solvothermal synthesis between 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato iron (Fe-OCAP) and 1,2,4,5-tetramino-benzoquinone (TABQ). Due to the robust fused aromatic backbone, the porous framework structure, and the natural Fe-N4 high active sites, the newly developed FePc-BBL COF exhibits unusual oxygen reduction reaction (ORR) activities and fast kinetics with a remarkable half-wave potential of 0.933 V and an ultralow Tafel slope of 24.8 mV dec-1 in alkaline media. In addition, the FePc-BBL COF also exhibits an ultrahigh turnover frequency (TOF) of 78.1 e- site-1 s−1 at 0.85 V vs. RHE and mass activity of 26.5 A mgFe-1, represents 16.4- and 57.2-fold enhancements compare to Pt/C. Furthermore, when employed as a cathode electrocatalyst for zinc-air batteries, FePc-BBL COF delivered superior maximum power density (181.4 mW cm−2), specific capacity (773 mAh g−1), and long-term durability compared with Pt/C as air electrodes. This work provided a promising strategy in engineering reticular materials to design highly stable and efficient pyrolysis-free electrocatalyst for practical value sustainable energy conversion and storage devices.

Spin filtration in an antiferromagnetic ladder

In this work we explore how a two-stranded magnetic ladder with vanishing net magnetization can be utilized to generate polarized spin current from a completely unpolarized one. Considering three different types (A-, C- and G-type) of antiferromagnetic ladders within a tight-binding framework, we make a comparative study to find the best suitable ladder for spin filtration. Our analysis can be implemented to design efficient spintronic devices with the help of antiferromagnetic materials, circumventing the use of conventional ferromagnetic systems.

Weight optimization of heavy-duty truck chassis by optimal space fill design using light weight Graphite Al GA 7-230 MMC

Heavy duty vehicles e.g., trucks are one of the important mediums of ground transportation in every sector like defence, road transport etc. which provides immediate support whenever required. Innovative technological development in the area of automobile has been growing very rapidly, especially in the developing scenario. This development leads to the requirement of reducing the weight of the vehicle specially the chassis frame which serves as a skeleton to provide the proper structural safety to a vehicle & hence affects the vehicle’s performance along with the requirement of fuel consumption. It is a critical part in the vehicle, and various sorts of failures happen because of static loading conditions. Decreasing the heaviness of the vehicle parts is an ideal answer for the issue. The presented work focuses on optimizing a heavy-duty TATA 1612 truck chassis (ladder type frame) by substituting its material from conventional steel with potential metal matrix composite light weight Graphite Al GA 7–230 MMC material without compromising the safety and strength. CAD modelling & structural analysis is accomplished on the modelled frame using ANSYS and optimal space filling design scheme of response surface method respectively. Analysis shows around 70% reduction in mass of chassis and thus subsequently affect the functioning of the vehicle in a positive approach.

Design and Analysis of Chassis of Four-Seater Car

Abstract: The initial dimensions and weight for the vehicle is considered from the Audi A8 vehicle as a reference. The specifications for the motor and battery are considered for the Mahindra e2o electric vehicle of similar dimensions. The main objective of this paper is to model and perform static analysis on the chassis of a four-seater car. The initial design for the chassis was a space frame body which is very rigid and had very less deflection. The second and final chassis is a ladder type chassis which is most common chassis type being used in Nepal and India. The difference in deflection between both the chassis type is very less, which is about 0.3235 mm for a reasonable reduction in weight which is about 120 Kg. The simulation part is carried out in ANSYS software. The result is selection of best suitable material for chassis on the basis of ANSYS and theoretically calculated result. Keywords: Chassis, Structural Analysis, Optimization, Four seater car

A second law analysis on flow of a nanofluid in a shell-and-tube heat exchanger equipped with new unilateral ladder type helical baffles

The irreversibility characteristics of a shell and tube heat exchanger (STHE) fitted with the unilateral ladder type helical baffle are investigated. A boehmite nanofluid having different nanoparticle shapes is used as the hot fluid in the tube-side with a constant Reynolds number. The pure water is applied for the cold fluid, which passes inside the shell with various Reynolds numbers. The thermal and frictional entropy productions of both fluids intensify by the Reynolds number amplification. Thereby, the plural entropy production rates of the hot fluid and cold fluid, in the condition of utilizing the platelet nanoparticles, respectively demonstrate 8.4% and 20.9% increases by the Reynolds number variation from 5000 to 20,000. The nanofluid containing the platelet nanoparticles causes the maximum thermal entropy production. All in all, the minimum irreversibility for the whole STHE occurs for the nanofluid containing the oblate spheroid particles, which is recommended for use in this STHE.

Dynamic feed spacer for fouling minimization in forward osmosis process

In this study, a dynamic feed spacer is used to minimize the fouling problem of forward osmosis (FO) membrane process. The conceptual design of the spacer consists of a series of microturbines assembled in ladder type filament cells and termed as turbospacer. It exploits the kinetic energy of the flowing feed solution to rotate the turbines and creates high flow turbulence in the feed channel to prevent the accumulation of foulants and related performance decline. This proof of concept study employed a 3D printed prototype of the proposed spacer in a lab-scale FO experimental setup to compare their performances with a symmetric non-woven spacer of the same thickness under the same operating condition as a reference. Primary effluent from municipal wastewater treatment plant was used as feed solution for a short term (6 days) fouling experiment in this study. Outcomes of the FO fouling experiment revealed that the turbospacer resulted in (i) a factor 2 lower spacer channel pressure drop built-up, and (ii) a 15% reduction in flux decline compared to the reference symmetric spacer. Almost 2.5 times lower foulant resistance was obtained by using the turbospacer at the end of the fouling experiment. In addition, the analysis of the foulant layer growth over a particular position of the membrane surface captured by an optical coherence tomography (OCT) device at different stages of the experiment exhibited that the turbospacer produced a thinner foulant layer. In summary, the turbospacer demonstrated better fouling prevention and control in the FO process.

Ladder Type of Leaky Surface Acoustic Waves Filters on Substrate of Lithium Niobate

High requirements on the electrical parameters of the filters are made in wireless radio communication systems. A number of tasks require bandpass filters with relative bandwidths of 8-12 %. In this case, the filter must have insertion losses of not more than 10 dB, have a rejection is not worse than 40 dB, unevenness in the bandwidth of not more than 1 dB. In addition, the amplitude frequency responses of the filter must have steep slopes due to the closely spaced frequency bands of neighboring communication systems. Due to its small size and other advantages, ladder resonator filters on surface acoustic waves are widely used in communication systems. To realize the high requirements of this type of filters, it is necessary not only to select all the topology parameters of the individual resonators included in the filter very accurately, but also to have a good computational theory and the necessary material parameters for the selected model at the design stage. Purpose: to show on the example of comparison of calculated and experimental frequency responses of ladder filters the validity of the method of extraction of the necessary parameters obtained for an infinite periodic structure by the finite element method for calculating of finite structures of real inter digital transducer and reflective gratings. Results: the method of extraction of parameters necessary for calculation by the method of connected modes on the basis of P-matrices is offered. The technique is based on the analysis of infinite periodic electrodes by the finite element method. Bandpass filters with a relative bandwidth 8-12 % on a piezosubstrate 49° YX LiNbO3 were designed and manufactured based on the proposed theory. It is shown that for this material, the calculation must take into account the direct radiation of bulk acoustic waves, since the design of ladder type filters, the radiation falls into the projected bandwidth of the filters. These calculations are confirmed by the results of experiments.

A CFD study on thermohydraulic characteristics of a nanofluid in a shell-and-tube heat exchanger fitted with new unilateral ladder type helical baffles

The present study aims to research the thermohydraulic characteristics and performance index for flow of the nanofluids containing varied particle shapes including cylinder, blade, brick, platelet, and Oblate Spheroid (OS) in a shell and tube heat exchanger (STHX). The STHX is equipped with new unilateral ladder-type helical baffles to develop spiral stream inside the shell side. The nanofluid is assumed as the hot fluid that passes inside the tube side. Water is selected for the cold fluid that flows within the shell side with Reynolds numbers of 5000 to 20,000. The flow pattern developed by the baffles has noticeable impacts on the STHX performance. By the rise in the Reynolds number of the shell side, the heat transfer rate, overall heat transfer coefficient, effectiveness, Number of Transfer Unit (NTU), and pressure drop increase, whereas the performance index decreases. Moreover, the highest heat transfer rate, overall coefficient, and pressure loss belong to the nanofluid containing the platelet additives, while the greatest effectiveness, NTU, and performance index happen for the nanofluid with the OS additives. The severe cross and secondary flows are completely obvious in the shell side due to the existence of the new baffles, specially at high Reynolds numbers.

A Simple PCR-Based Method for the Preparation of DNA Size Markers

DNA size markers are widely used in molecular biology laboratories as DNA molecular weight standards. In this paper, I report a simple and convenient method for the preparation of DNA ladders using PCR technique. DNA ladders usually range from 100 bp to 10 kb, and many such 100 bp and 1 kb DNA ladders are commercially available. Conventionally, 100 bp to 5 kb DNA fragments were amplified using standard PCR with Taq DNA polymerase, and the large DNA fragments exceeding 5 kb were amplified using long-range PCR with a special thermostable polymerase. In this study, several types of DNA ladders were prepared by mixing the amplified DNA fragments in different combinations, which can be used as DNA size standards in agarose gel electrophoresis.

Titanicking the Clamshell. Anchoring the Bilateral Thoracosternotomy Incision with Titanium Plates, Screws and Sternal Band. Our Experience in Fifty Consecutive Patients of Double Lung Transplantation

Purpose Clamshell incision for double lung transplantation offers unmatched advantages . But prolonged immunosuppresion therapy along with corticosteroids can lead to sternal healing abnormalities, overriding, gaping and cut through injuries on usage of sternal wires for closure . We have modified sternal closure technique using H shaped titanium plates, screws and sternal bands. The review of data on such closure of sternum in fifty consecutive lung transplant shows reduced healing complications of the sternum. Methods Our thoracic organ transplant services team has done 142 double lung transplantation from february 2017 to till date. We have been using H shapped ladder type titanium plates with 2.4 mm cancellous self tapping screws and a single sternal band. We retrospectively reviewed and compared data between fifty conventional closure (stainless steel wire technique) versus titanium plate and sternal band closure in fifty recipients. Results We observed that 15 patients (30%) in conventional Closure group had some sternal healing complications such as over riding(4 patients 8%), complete dehiscence(3 patients 6%), wire cut through(3 patients 6%)wire protruberance (3 patients 6%)and sternal mobility (2 patients 4%). Only one patient (2%)in titanium plate closure had sternal mobility, there were no other complications in the latter subset. Conclusion Titanium plate closure, has lesser healing complications of sternum, making this method a regular closure strategy for all our double lung transplantation recipients.

Addition of angled rungs to the horizontal ladder walking task for more sensitive probing of sensorimotor changes.

One method for the evaluation of sensorimotor therapeutic interventions, the horizontal ladder walking task, analyzes locomotor changes that may occur after disease, injury, or by external manipulation. Although this task is well suited for detection of large effects, it may overlook smaller changes. The inability to detect small effect sizes may be due to a neural compensatory mechanism known as “cross limb transfer”, or the contribution of the contralateral limb to estimate an injured or perturbed limb’s position. The robust transfer of compensation from the contralateral limb may obscure subtle locomotor outcomes that are evoked by clinically relevant therapies, in the early onset of disease, or between higher levels of recovery. Here, we propose angled rungs as a novel modification to the horizontal ladder walking task. Easily-adjustable angled rungs force rats to locomote across a different locomotion path for each hindlimb and may therefore make information from the contralateral limb less useful. Using hM3Dq (excitatory) Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) expressed in large diameter peripheral afferents of the hindlimb in the intact animal, we characterized the sensitivity of our design to detect stepping differences by comparing locomotor changes observed on angled rungs to those observed on a standard horizontal ladder. On our novel asymmetrical ladder, activation of DREADDs resulted in significant differences in rung misses (p = 0.000011) and weight-supporting events (p = 0.049). By comparison, on a standard ladder, we did not observe differences in these parameters (p = 0.86 and p = 0.98, respectively). Additionally, no locomotor differences were detected in baseline and inactivated DREADDs trials when we compared ladder types, suggesting that the angled rungs do not change animal gait behavior unless intervention or injury is introduced. Significant changes observed with angled rungs may demonstrate more sensitive probing of locomotor changes due to the decoupling of cross limb transfer.

Investigation through analytical studies and experimental validation of ladder type resonant converter based constant current charger (>20 kW) for charging applications

As the world is moving towards green transportation, an effective charging infrastructure is needed to meet the demand of electric vehicles (EVs) with different power ratings. High power DC charging will facilitate EVs to charge quickly and reduce the wait time of a customer. As present charging infrastructure is limited to low power and is not compatible with different rated modular battery packs of EVs, this paper demonstrates Resonant Converter (RC) based high power constant current DC Fast charger. Owing to its inherent sensitivity, RCs suffer and fail to maintain rated load current when subjected to deviation in switching frequency and this has been the limiting feature for which they are not explored much in the automobile sector. In light of it, a topology study of about 25 RCs under lumped T, π, Ladder, and branch type structures is reported and examined the frequency dependence of different characteristic parameters in a range of frequencies encompassing the resonant frequency. This investigation conceived a novel RC that has adequate immunity in dealing with frequency sensitivity and also capable of pumping high DC power. The proposed converter is verified with a prototype and results are in close agreement with design.

Structures with different supramolecular interactions and spectral properties of monomeric, dimeric and polymeric benzoatocopper(II) complexes

Three new monomeric benzoatocopper(II) complexes [Cu(3-MeObz)2(4-PM)2] (1), [Cu(3-Mebz)2(4-PM)2] (2) and [Cu(4-Mebz)2(4-PM)2] (3), two polymers [Cu2(2-Mebz)4(4-PM)]n (4) and [Cu2(3-Mebz)4(4-PM)]n (5), and the dimeric complex [Cu2(2-Fbz)4(4-PM)2] (6) (where 4-PM = 4-pyridylmethanol, 2-Fbz = 2-fluorobenzoate anion, 3-MeObz = 3-methoxy-benzoate anion and x-Mebz = 2-,3- or 4-methylbenzoate) have been synthesized and characterized by elemental analysis as well as by single-crystal diffraction. All the complexes have been studied by infrared, UV–vis and EPR spectroscopy. The neutral ligand 4-PM acts as a terminal ligand in 1–3 and 6, and as a bridging ligand in 4 and 5. The structural motives are evident in the EPR spectra, which have shown axial symmetric features for 1–3, whilst the polymers as well as the dimer (4–6) have exhibited an acetate-type feature. The monomeric complex molecules of 1–3 and the dimeric molecules of 6 are linked by terminal 4-PM H-bonds to create 2D supramolecular square-grid hydrogen-bonded networks. On the other hand, the 1D polymeric chains of 4 are linked into a 2D supramolecular network, while two coordination chains of 5 come together to generate a ladder type double chain.

Isotope selective three-step photoionization of 176Lu

Numerical computations of ionization efficiency and isotope selectivity of 176 L u have been carried out for the following three-step ladder type photoionization scheme, 5 d 6 s 2 2 D 3 / 2 ( 0.0 c m − 1 ) − − − ⟶ 540.4068 n m ⁡ 5 d 6 s 6 p 4 F 5 / 2 o ( 18504.58 c m − 1 ) − − − ⟶ 535.0626 n m 5 d 6 s 7 s 4 D 3 / 2 ( 37193.98 c m − 1 ) − − − ⟶ 618.0061 n m 53375 c m − 1 A u t o i o n i z a t i o n S t a t e → L u + , by invoking the density matrix formalism for the laser–atom interactions. Equations of motion have been derived for the odd isotopes by inclusion of hyperfine levels. The line shapes and their effect on the ionization efficiency and isotope selectivity have been discussed in detail. The effects of power of excitation and ionization lasers, spectral bandwidths, pulse delays, Doppler broadening of the atomic ensemble on the ionization efficiency, and degree of enrichment have been presented. Optimum conditions for the power of excitation, detunings, and other system parameters for the selective yet efficient photoionization of 176 L u have been identified.

Performance analysis of reduced switch ladder type multilevel inverter using various modulation control strategies

Multi-Level Inverters (MLI) are finding applications in UPS, drives, Grid interfaces because of dynamic output voltage control capability. In this paper a nine level single phase MLI topology with optimized switches is proposed. Increased output level helps in smoothening the output waveform along with reduced THD and eliminates need of filtering circuits. Proposed Reduced Switch Ladder Type MLI (RSL-MLI) topology consists of four DC power sources and nine switches for single phase inverter. When compared to conventional MLIs for same nine output levels, this topology has less number of devices making it cost effective. Both, high frequency switching pulse width modulation and fundamental frequency switching modulation methods are used for simulation of proposed nine level RSL-MLI topology. Output voltage waveform, THD are analysed using Simulink and equated to validate the performance of planned topology. Further, simulation is carried for five and seven levels of output voltages and THD are analysed.

Hydraulic calculation of fish ladders, Sebesel River, Romania

Sebesel 1 hydropower development is located on the Sebesel River, in the outskirts of Borlova, Caraş-Severin County. The realization of the fish ladder will not influence the flow regime of the surface or groundwater in the neighboring area. The fish ladder is dimensioned so as to allow the migration of the ichthyofauna upstream during the spawning period and the partial transit of the alluviums as well as the downstream provision of a servitude flow Q = 0.059 mc / s. The Sebeşel 1 hydroelectric power plant is a hydropower arrangement by shunt without accumulation lake. The plant has two power groups equipped with Pelton turbines. The power delivered by MHC Sebesel 1 is 876.03 kW. The installed flow rate is 0.90 m3 / s; gross fall: 131 m; capture rate 814 mdMN. The fish ladders are of the technical ladder type with pools. The objectives of the studies were: to describe the qualitative and quantitative structure of benthic invertebrate and fish macro communities; assessment of the ecological status of the rivers in the areas of hydropower development; highlighting the presence of fish species of conservative interest and assessing the status of their populations. The methodology was carried out in accordance with the provisions of the Water Framework Directive, Annex V used took into account the following: Assessment of the status of aquatic communities; description of the structure of fish communities; assessment of the ecological status of the river sectors. The study led to obtaining some essential information for the exploitation and maintenance of the micro-hydroelectric plant as well as the fish ladder.

Near-infrared light-mediated Er3+ and Yb3+ co-doped CaTi4O9 for optical temperature sensing behavior

In present report, CaTi4O9: 1 at% Er3+, 1 at% Yb3+ phosphors have been synthesized via sol-gel method and reported herein for its temperature sensing performance. XRD spectra confirms high crystallinity and successful inclusion of rare earth (RE) ions into CaTi4O9 as the dopant ions do no induce any change in the peak position. The X-ray diffraction analysis indicates that the host calcium titanate exhibits hexagonal crystal structure. The green up-conversion (UC) emission observed using 980 nm diode laser excitation. Since, Er3+ ion has ladder type energy levels, thereby it receives energy from Yb3+ ion by excited state absorption and energy-transfer up-conversion processes. Furthermore, the Er3+ ion has two temperature sensing levels 4S3/2→4I15/2 (550 nm) and 2H11/2→4I15/2 (525 nm). Therefore, temperature dependent up-conversion spectra illustrate good temperature sensitivity for present phosphor. The sensitivity of above mentioned phosphor has been evaluated with temperature from 300K to 500K, which shows the suitability of the phosphor for developments in temperature thermometry.

Measurement of multi-frequency dispersions of Electromagnetically Induced Transparency windows using Spatial Light Modulator in rubidium vapor

In this letter, we have measured the dispersive profile of the multi window Electromagnetically Induced Transparency(EIT) signals in Rubidium (Rb) atomic medium at room temperature. Weak probe laser light and strong coupling light in counter propagating direction are used to excite the atomic medium via ladder type configuration of87Rb D2 line to obtain multiple EIT peaks. The uniqueness of our work is in the experimental setup which is used for the measurement of dispersion. We have used transmissive Spatial Light Modulator(SLM) in one arm of the Mach–Zehnder(M–Z) interferometer to obtain the desired phase shift between two interfering arms for the measurement of dispersive properties of multi window EIT in Rb vapor medium. One can easily obtain the phase shift without disturbing the alignment of the M-Z interferometer by using this setup.

Highly non-resonant lasing without inversion gain in a ladder scheme

We show that it is possible to get gain without inversion at high frequency in a three-level ladder type scheme driven by a single driving laser. The transition from the ground state to first excited state is driven by a low-frequency resonant laser field. The next excited state lies far above the first one; therefore its resonant frequency can be much higher than that of the lower transition, and hence one should go beyond the most commonly used rotating wave approximation consisting of retaining only resonant terms (slowly oscillating) in the Hamiltonian. We solve the master equation, both analytically (under proper approximations) and numerically, with the full Hamiltonian keeping counter-rotating highly non-resonant terms. We show a dressed state picture explaining spectral features of gain-absorption profiles. Also we present a kind of phase diagram in the plane γ–Λ, where γ and Λ are spontaneous emission rate and incoherent pumping rate, respectively. The whole γ–Λ plane is divided into four areas: gain-inversion, absorption-no inversion, gain without inversion and absorption with inversion. The first two are usual regimes of incoherently pumped lasers, while the last two stem from the quantum interference phenomena. We analyse the parameter areas where such quantum regimes are possible. The exact numerical solution of the time-dependent master equation shows that keeping counter-rotating terms (no rotating wave approximation) gives rise to new spectral features in the form of additional peaks at combination frequencies. Actually the considered system works as a coherent frequency up-converter.

Design of multilayer microfluidic paper chip and its visual detection of pesticide residues

With the increase of China's grain production, the use of pesticides is gradually increasing. Traditional pesticide detection takes a long time and requires expensive experimental instruments, which is not conducive to the rapid and accurate detection of pesticide residues in the field. To solve this problem, this paper proposes a visual detection method of pesticide residues based on multi-layer microfluidic paper chips. The internal channel structure of paper chip is designed from the perspective of efficient mixing. Through the simulation of the mixed effect of three kinds of staggered channel structures, which are arc type, triangle type, and ladder type, the "ladder-type h-0.3, s-2.6" is selected as the best-staggered structure, and the mixing strength is 0.91534. The best simulation structure was tested by a colored reagent, and the image processing of 15 test results was carried out with MATLAB. The average mixing strength was 0.84, and the and the standard deviation was 0.022. The visual detection experiment of acetamiprid and profenofos in cabbage samples was carried out by using the device，The detection range of acetamiprid was 4~72 μg/kg, and the detection range of profenofos was 3~54 μg/kg . The recovery of acetamiprid was 75%~85%, and the recovery of profenofos was 80%~90%. The detection range and recovery rate indicate that the device has high repeatability and accuracy in the actual sample detection