Separate Systems Research Articles

Determination of the hydrogen-bond basicity descriptor by reversed-phase liquid chromatography

Except for alkanes, most organic compounds are hydrogen-bond bases. The B° descriptor of the solvation parameter model provides a convenient measure of the effective (or summation) hydrogen-bond basicity of organic compounds. A fast and convenient method to assign the B° descriptor is required to support studies of hydrogen-bonding in separation systems. A two-column system with acetonitrile-water mobile phase compositions and the measurement of up to eleven isocratic retention factors is proposed for this purpose. Several reversed-phase column chemistries and mobile phases were evaluated with the two-column system consisting of a pentafluorophenylpropylsiloxane-bonded and octadecylsiloxane-bonded silica columns recommended for this purpose. To assess the accuracy of the method values for B° were taken from the Wayne State University (WSU) compound descriptor database, which were assigned using conventional multi-technique methods and large datasets. The two-column systems provided an unbiased assignment of B° with an average deviation of 0.008 and an average absolute deviation of 0.021 compared with the target value for 55 varied compounds. The two-column system is unsuitable for assigning the other descriptors used in the solvation parameter model and results in erroneous assignments of B° for nitrogen-containing compounds capable of electrostatic interactions on silica-based reversed-phase columns.

Development of composite ceramic/polymeric hollow fibre membrane for water separation at low pressure and ambient temperature

This study proposed an enhanced water purification separation that was carried out at ambient temperature and low-pressure system. ZnO and PVA layers were deposited on the outer surface of Al2O3 hollow fibre membrane, and this composite membrane was used to separate synthetic salt solutions with a concentration of 40,000 ppm. The salt solution was introduced on the outer surface of PVA–ZnO–Al2O3 hollow fibre membrane, and distilled water was flowed through the lumen as draw solution. The PVA–ZnO–Al2O3 hollow fibre membrane showed a water flux of 25.70 kg m2 h−1 with 93.9 % NaCl rejection. Al2O3 hollow fibre used in this work possessed asymmetric structure with permeability of 11.6 mD and was identified as a medium that cause a significant pressure drop within the separation system. A considerable pressure drop occurred in the porous region of the ceramic hollow fibre, causing water to vaporise. This phenomenon resulted in water evaporation at the interface between the dense sponge-like region of Al2O3 hollow fibre and PVA–ZnO membrane, thus created a positive flux for enhanced salt separation.

Thinkings on the reform of medical education system in China

Thinkings on the reform of medical education system in China

Development of advanced hybrid computational model for description of molecular separation in liquid phase via polymeric membranes

Separation of molecules using membranes has been computationally studied in this work for understanding the separation process and also assessment of integrating machine learning (ML) techniques to computational fluid dynamics (CFD) techniques. We initially performed CFD computations to simulate mass transfer in a membrane-based molecular separation system, and then exported the mass transfer data for training ML models. Indeed, a hybrid model was developed and employed for membrane process in separating a solute from a solution. We have modeled a data set containing more than 14 thousand data rows, which has two inputs r (m) and z (m) and single response, i.e., C (mol/m3) that is solute’ content in the solution. Decision tree-based models are used in this modeling. Simple Decision Tree (DT), Boosted Decision Tree (BDT) that is DT alongside AdaBoost, and Random Forest (RF) are the selected models for this research. The ML techniques were further optimized via a novel HHO algorithm. Final assessments show the R2 scores of 0.9991, 0.9874, and 0.9997 respectively for BDT, DT, and RF models. Based on this result and other analysis, RF is selected as the best method in this study for simulation of membrane process. This model has an RMSE error rate of 2.22 × 103.

Design and multi-objective optimization of combined air separation and ORC system for harnessing LNG cold energy considering variable regasification rates

Regasification of liquefied natural gas (LNG) releases significant cooling potential, but improper usage can easily lead to wastage of resources and environmental pollution. The study developed an integrated air separation system and Organic Rankine Cycle (ORC) power generation system to effectively harness the inherent cold energy within LNG. Two distinct optimization algorithms, the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) and the Particle Swarm Optimization (PSO), were employed to determine the optimal operational parameters. The results showed the superior performance of PSO over NSGA-II, as demonstrated by the exergy efficiency, net output power, and levelized cost of energy at 78.12 %, 2.29*1011 kW, and 0.0665 $/kWh, respectively. Additionally, an assessment of various factors influencing the system's performance was conducted. The performance of both conventional and proposed systems was studied under varying regasification rates. The findings indicated that incorporating the cold recovery and storage unit enhanced the efficient utilization of LNG cold energy, resulting in an increased valley-to-peak ratio of the total power output from 0.03 in the conventional system to 0.5. The proposed system exhibits alignment with the energy consumption demands of users, and this study is anticipated to furnish a theoretical foundation for harnessing the cooling capacity of liquid hydrogen.

Optimal design of a clamp band system based on genetic algorithm and experimental verification

As one of the most common separation systems, the clamp band system (CBS) is widely used in the process of connection and release of spacecraft with the launch vehicle. An optimal design method and a separation shock response estimation method were proposed for a large-diameter CBS in this paper. First, a new application based on the parameter modeling method of MSC.Patran and genetic algorithm (GA) was proposed to design the CBS. Finite element techniques for 2D axisymmetric analysis of the CBS were developed, including the modeling of V-clamp, strap pre-tension, and loads, then the optimizing constraints and objectives were also defined. Secondly, a CBS with a diameter of 3 m was designed via the proposed method, which is verified by the 3D finite element analysis under MSC.Marc and a stiffness experiment. Thirdly, the separation process of the CBS and its high-frequency and high-amplitude shock response were calculated by an explicit dynamic solver, and the differences between the model and experimental results were discussed. Finally, a single degree of freedom (SDOF) spring-mass system was constructed to predict the weakening effect of the delay time on the shock response. The slow-release device was designed and the experiment was completed to verify the effectiveness of the method.

Experimental investigation on the characteristics of a controllable separate heat pipe-based cold storage temperature control system

PCM cold storage systems have been widely employed in household refrigerators due to their economy and efficiency. However, the PCM heat transfer process is out of effective control, limiting the accurate temperature control ability of the system. Herein, a controllable separated heat pipe that can regulate heat transfer is introduced into the PCM cold storage system to resolve its issues. A novel controllable separate heat pipe-based cold storage temperature control system is proposed. The dynamic temperature control ability and cold storage characteristics of the system under various operating conditions are revealed through experiments. As a result, the spatial inhomogeneity of the temperature field of the PCM is discovered which is related to the unsteady heat transfer between the PCMs in different regions and to the on–off state of the controllable separate heat pipe. In the discharging mode, the stable temperature control time of the compartment decreases by 53% when the temperature decreases from 7 °C to 1 °C. In addition, a lower inlet temperature of the ethylene glycol solution results in faster cold storage rates and greater temperature differences of the PCMs in different regions (the maximum temperature difference is 3.47 °C when the inlet temperature is −26 °C). Moreover, the results of door opening experiments show that the temperature can be controlled within an accuracy of 2.5 °C when the door opening time is 60 s, demonstrating the temperature regulation ability of the system. The results verify the feasibility of the technical route and provide a valuable reference for the optimization of precise temperature control systems.

Adaptive fuzzy sliding-mode control of under-actuated systems with unknown input gain function

This research addresses the design of an Adaptive Fuzzy Sliding-Mode Control (AFSMC) for a group of nonlinear under-actuated systems with unknown input gain functions. In the proposed approach, to provide a structure for controlling the under-actuated subsystem, the sliding manifold corresponding to the whole dynamic system is derived based on the backstepping technique. In addition, two separate fuzzy inference systems are utilized for approximating the system’s internal dynamics and the unknown input gain function. In order to derive the robust part of the controller, a novel method is proposed to define the upper bound of the uncertain term in the form of a state-dependent second-degree polynomial. It should be mentioned that the output vectors of the fuzzy systems and the coefficients of the robust part of the controller are obtained by the designed adaptation laws. The asymptotic stability analysis for the proposed AFSMC structure is provided by the second theorem of Lyapunov and Barbalat’s lemma. In the end, the AFSMC effectuality is confirmed by the depth control of a REMUS Autonomous Underwater Vehicle (AUV).

Liquid-solid phase separation and recycling of permalloys in liquid Mg

Liquid-solid phase separation of permalloy in liquid Mg results in selectively dissolved Ni, which provides a unique opportunity for the design of immiscible heterogeneous composite materials and the comprehensive metal recycling of permalloy scraps. A guideline of the alloy design for the liquid-solid phase separation system was proposed. The effects of immersion temperature and time on the Ni extraction were studied by an experimental method. The diffusion behavior of Ni from the permalloy to liquid Mg and the microstructure evolution in the permalloy during the liquid-solid phase separation were discussed. The results show that the Ni in the permalloy was quickly extracted into the liquid Mg and formed an Mg-Ni alloy, while the other components such as Fe, Co, and Mn were held back in the phase-separated permalloy. The phase-separated permalloy with the solidified Mg exhibits a three-dimensional (3D) Fe/Mg bicontinuous composite structure. Furthermore, simple treatments were carried out for the reaction products such as the Fe/Mg bicontinuous composite and the Mg-Ni alloy, and the recycling strategies for functionalization of these treated reaction products were provided. A 3D porous Fe-based alloy with electromagnetic interference (EMI) shielding efficiency of 52 dB can be obtained if Mg is removed from the Fe/Mg bicontinuous composite. Instead of the complete separation of pure Ni from the recycled Mg-Ni alloy by vacuum distilling, the Mg-Ni alloy can be enriched into Mg2Ni as an initial hydrogen storage material.

Table-top numbering-up 3D-printed miniaturized hydrocyclone for high-efficiency and high-throughput separation of oil-in-water emulsions

Oily wastewater from home and industrial effluents, as well as marine oil spills, poses significant environmental problems, such as water and soil contamination and ecosystem devastation. We here developed a parallelized miniaturized hydrocyclone (mHC) system consisting of multiple mHCs and a flow distributor for high-efficiency and high-throughput separation of oil-in-water emulsions. From a manufacturing perspective, our system can be easily and rapidly created using 3D printing technology. It was also specifically designed to provide simple and durable connections between tubes and components, eliminating the need for a time-consuming bonding process. Direct visualization of primary and secondary vortex flows generated within the mHC device was achieved, allowing the variation of the vortex flows as a function of the feed flow rates to be analyzed. Furthermore, we demonstrated that a single mHC was capable of separating six types of oil-in-water emulsions with different oil phases and a separation efficiency greater than 90 %, with olive oil-based emulsions achieving a remarkable separation efficiency of 98.3 % at the optimal feed rate of 200 mL/min. By numbering-up a single mHC and incorporating a 3D-printed flow distributor to ensure a uniform flow distribution into each individual mHC, we can construct a parallelized mHC system. The separation system can process an estimated 3,168 L (837 US gallons) of mineral oil-based emulsion per day with a separation efficiency of approximately 97 %. The results of this study can be further enhanced by modifying the flow distributor, increasing the number of single mHCs, and introducing high-performance pumps.

Sustainable development and multi-aspect analysis of a novel polygeneration system using biogas upgrading and LNG regasification processes, producing power, heating, fresh water and liquid CO2

Considering biogas upgrading to feed energy systems and its significant impact on the biogas energy density, a novel polygeneration system utilizing biogas from landfill waste is designed, simulated, and studied in this paper. The primary innovation is to design a biogas upgrading technology for a novel multigeneration system using a thermal matching approach. This system is capable of simultaneously generating power, providing heating, producing fresh water, and extracting liquid carbon dioxide in an environmentally sustainable manner, thus resulting in reduced environmental impacts. For this purpose, a cryogenic separation system based on liquefied natural gas cold utilization is employed for biogas upgrading and biomethane separation. The proposed process also consists of a Kalina cycle, an organic Rankine cycle, a multi-effect desalination technology, and a heating provider unit. This system is simulated within the Aspen HYSYS software and is undergone a comprehensive analysis from the viewpoints of energy, exergy, environmental, and economic. The results indicate that the proposed structure achieves energy and exergy efficiencies of 80.91% and 43.76%, respectively. Environmental assessment reveals that the emission intensity is 90.43% lower in polygeneration mode compared to power generation mode, and the system’s net emission is equal to 23,041.51 kg/h. The economic evaluation demonstrates that the total unit cost of products is minimized in polygeneration operation (1.84 $/GJ), while it is highest in power generation condition (7.564 $/GJ). The investigations show that when a system is modified from a single generation to polygeneration, all thermodynamic, economic, and environmental indicators face an improvement.

Dynamic fluorescence imaging and controllable capture/release of guests based on thermo-responsive perylene-cyclodextrin conjugates

In view of the fact that multivalent intermolecular noncovalent interactions are the main elements for the formation of phase separation, supramolecular entities are a type of multivalent system. However, the phase separation system based on single supramolecular molecules was limited. In this paper, two permethyl-β-cyclodextrin modified perylene monoamide derivatives (PMI-B-CD and PMI-N-CD) with modification of benzene and naphthalene groups at the bay position of perylene backbone were synthesized. Of interest, PMI-B-CD and PMI-N-CD showed a LCST effect due to a self-inclusion interaction between PMCD and the benzene or naphthalene groups in the bay position of perylene monoamide backbone. Dynamic confocal fluorescence imaging of PMI-B-CD and PMI-N-CD showed thermo-responsive phase separation process. It is surprised that PMI-B-CD and PMI-N-CD achieved thermo-responsive capture and release of aromatic guests. Dynamic phase separation and controllable capture and release of guests with thermo-responsive phase transition process are found, which opens a novel supramolecular principle of liquid-liquid transition.

Dry particle size separation using electrostatic traveling wave methods

Electrostatic traveling wave (ETW) methods have grown in popularity as a method to manipulate and separate fine particles. This is of interest to mineral processing and In-situ Space Resource Utilization. Here, we demonstrate that ETW can be used to separate particles by size. First, our numerical calculation and simulation results show the competing effect of DEP and Coulomb force on particle motion direction, which depends on the frequency, particle size and charge. Then we define the “crossover frequency” allowing prediction of operating parameters to separate particles. At the “crossover frequency” – a particle is equally likely to move forward or backward. The crossover frequency decreases as particle size increases, and the proportion of particles moving backward increases as frequency increases. Four size groups of ballotini particles (glass) were transported and collected at different wave field frequencies. Finally, we have demonstrated experimentally the separation of particles between 30–50 µm and 75–110 µm. Simulation and experiment results revealed the effects of frequency, particle size and charge on particle motions. And the model can be used to guide the design of separation systems.

Na10Zn(NO3)4(SO3S)4: a nonlinear optical crystal combining inorganic π-conjugated and non-π-conjugated heteroanion groups

Combining non-π-conjugated heteroanionic groups and π-conjugated groups is an effective strategy for obtaining crystals with excellent optical properties.

Integrable Magnetic Fluid Hyperthermia Systems for 3D Magnetic Particle Imaging.

Background: Combining magnetic particle imaging (MPI) and magnetic fluid hyperthermia (MFH) offers the ability to perform localized hyperthermia and magnetic particle imaging-assisted thermometry of hyperthermia treatment. This allows precise regional selective heating inside the body without invasive interventions. In current MPI-MFH platforms, separate systems are used, which require object transfer from one system to another. Here, we present the design, development and evaluation process for integrable MFH platforms, which extends a commercial MPI scanner with the functionality of MFH. Methods: The biggest issue of integrating magnetic fluid hyperthermia platforms into a magnetic particle imaging system is the magnetic coupling of the devices, which induces high voltage in the imaging system, and is harming its components. In this paper, we use a self-compensation approach derived from heuristic algorithms to protect the magnetic particle imaging scanner. The integrable platforms are evaluated regarding electrical and magnetic characteristics, cooling capability, field strength, the magnetic coupling to a replica of the magnetic particle imaging system's main solenoid and particle heating. Results: The MFH platforms generate suitable magnetic fields for the magnetic heating of particles and are compatible with a commercial magnetic particle imaging scanner. In combination with the imaging system, selective heating with a gradient field and steerable heating positioning using the MPI focus fields are possible. Conclusion: The proposed MFH platforms serve as a therapeutic tool to unlock the MFH functionality of a commercial magnetic particle imaging scanner, enabling its use in future preclinical trials of MPI-guided, spatially selective magnetic hyperthermia therapy.

Numerical analysis of superoleophilic-superhydrophobic filtration system for emulsions separation using lattice Boltzmann method

Numerical analysis of superoleophilic-superhydrophobic filtration system for emulsions separation using lattice Boltzmann method

Canadian Journalism: Two Centuries of Missed Opportunities (1608–1806)

The article analyzes how the events of the distant communication past affect the current information situation in the country based on the specific material of the two-century formation of a Canadian journalism. Under French rule, there were no printing houses and no press in Canada. Under the British regime, newspapers finally appeared, but English became the official language of the colony with a French-speaking population, and periodicals involuntarily, contrary to the proclamation of George III, chose “unofficial bilingualism”. However, the division of Canada by the political decision of the new metropolis into French-speaking and English-speaking ones in 1791 left its mark on all the subsequent development of journalism in the country: today two separate media systems continue to coexistt.

Design and Evaluation of Haptic Guidance in Ultrasound-Based Needle-Insertion Procedures.

This article presents two haptic guidance systems designed to help a clinician keep an ultrasound probe steady when completing ultrasound-assisted needle insertion tasks. These procedures demand spatial reasoning and hand-eye coordination because the clinician must align a needle with the ultrasound probe and extrapolate the needle trajectory using only a 2D ultrasound image. Past research has shown that visual guidance helps the clinician align the needle, but does not help the clinician keep the ultrasound probe steady, sometimes resulting in a failed procedure. We created two separate haptic guidance systems to provide feedback if the user tilts the ultrasound probe away from the desired setpoint using (1) vibrotactile stimulation provided by a voice coil motor or (2) distributed tactile pressure provided by a pneumatic mechanism. Both systems significantly reduced probe deviation and correction time to errors during a needle insertion task. We also tested the two feedback systems in a more clinically relevant setup and showed that the perceptibility of the feedback was not affected by the addition of a sterile bag placed over the actuators and gloves worn by the user. These studies show that both types of haptic feedback are promising for helping the user keep the ultrasound probe steady during ultrasound-assisted needle insertion tasks. Survey results indicated that users preferred the pneumatic system over the vibrotactile system. Haptic feedback may improve user performance in ultrasound-based needle-insertion procedures and shows promise in training for needle-insertion tasks and other medical procedures where guidance is required.

Dynamics and Stability of Interconnected Systems: A Graph-Theoretic Neuromorphic Approach

We investigate the stability of huge, linked subsystems in separate nonlinear dynamical systems. These systems' properties depend on both their dynamics and their link structure. We examine two concepts of stability. The initial one is connection stability, where a complete system is robust in the meaning of Lyapunov given the uncertainty and temporal fluctuations in the linking lengths among systems. The next is the widely accepted idea of asymptotic stability of the entire system, which is predicated on the premise that all linkages are set at the nominal values. We propose graph-based characteristics of two types of a stable for the situation of homogenous subsystems by making linkages to spectrum graph theory, in particular the spectrum of the sign adjacency matrix. We also obtain constraints on the highest amplitude of the sign adjacency matrix of independent relevance via this method.

Lubricin (PRG-4) anti-fouling coating for surface-enhanced Raman spectroscopy biosensing: towards a hierarchical separation system for analysis of biofluids.

Surface-enhanced Raman Spectroscopy (SERS) is a powerful optical sensing technique that amplifies the signal generated by Raman scattering by many orders of magnitude. Although the extreme sensitivity of SERS enables an extremely low limit of detection, even down to single molecule levels, it is also a primary limitation of the technique due to its tendency to equally amplify 'noise' generated by non-specifically adsorbed molecules at (or near) SERS-active interfaces. Eliminating interference noise is thus critically important to SERS biosensing and typically involves onerous extraction/purification/washing procedures and/or heavy dilution of biofluid samples. Consequently, direct analysis within biofluid samples or in vivo environments is practically impossible. In this study, an anti-fouling coating of recombinant human Lubricin (LUB) was self-assembled onto AuNP-modified glass slides via a simple drop-casting method. A series of Raman spectra were collected using rhodamine 6G (R6G) as a model analyte, which was spiked into NaCl solution or unprocessed whole blood. Likewise, we demonstrate the same sensing system for the quantitative detection of L-cysteine spiked in undiluted milk. It was demonstrated for the first time that LUB coating can mitigate the deleterious effect of fouling in a SERS sensor without compromising the detection of a target analyte, even in a highly fouling, complex medium like whole blood or milk. This feat is achieved through a molecular sieving property of LUB that separates small analytes from large fouling species directly at the sensing interface resulting in SERS spectra with low background (i.e., noise) levels and excellent analyte spectral fidelity. These findings indicate the great potential for using LUB coatings together with an analyte-selective layer to form a hierarchical separation system for SERS sensing of relevant analytes directly in complex biological media, aquaculture, food matrix or environmental samples.