Two-step Mode Research Articles

Glycerol Additive Boosts 100-fold Sensitivity Enhancement for One-Pot RPA-CRISPR/Cas12a Assay.

CRISPR/Cas12, a highly efficient and specific nucleic acid recognition system, has been broadly employed to detect amplified DNA products. However, most reported methods adopt a two-step detection mode that needs a liquid transfer step, thus complicating the detection procedure and posing a risk of aerosol contamination. A one-pot detection method can obviate these problems, but it suffers from poor detection efficiency due to the loss of amplification templates elicited by CRISPR/Cas12 cleavage. In this study, we discovered that a glycerol additive dramatically promoted the detection efficiency of the one-pot recombinase polymerase amplification (RPA)-CRISPR/Cas12a method. Compared with the glycerol-free version, its sensitivity was nearly 100-fold higher and was close to that of the canonical two-step method. Further investigation displayed that the enhanced detection efficiency was attributed to the phase separation of the RPA and CRISPR/Cas12a system during the initial phase of the RPA reaction caused by the glycerol viscosity. This highly efficient one-pot method has been triumphantly harnessed for the detection of African swine fever virus (ASFV) and SARS-CoV-2, achieving naked-eye readout through a smartphone-equipped device. The currently developed glycerol-enhanced one-pot RPA-CRISPR/Cas12a method can be an advantageous point-of-care nucleic acid detection platform on account of its simplicity, high sensitivity, and universality.

Optimization of Fenton process for concurrent COD removal and lower sludge production: Process intensification and impact of reagents dosing mode

The versatile applications of the advanced oxidation processes (AOPs) are considered promising options for wastewaters treatment. Among AOPs, the classical Fenton process (CFP) is well recognized in literature due to its notable advantages. But the drawbacks associated with the CFP are the main barrier to its extensive applications. The primary process's drawbacks are the high sludge production and high reagents requirement, making the process unsustainable. Hence, the present study aims to overcome these drawbacks and improve the process's performance. The reagents (Fe2+ and H2O2) dosage were adopted as the variable parameters and varied throughout the experiments at fixed pH 3 and a reaction time of 45 min. The experiments were performed in three different stages; stage I (S–I: single-step reagents dosing mode), stage II (S-II: two-step reagents dosing mode), and stage III (S-III: three-step reagents dosing mode) and landfill leachate was taken as a sample. The dosing mode of reagents was found to be a crucial influencing factor to improve the overall Fenton process's performance by effectively utilizing the hydroxyl radicals (•OH) and avoiding the scavenging reactions. The two-step reagents dosing mode was found better, i.e., 52 ± 2% chemical oxygen demand (COD) removal and 40 ± 2 mL sludge production compared to S–I and S-III with approximately 10–15% extra COD removal and low sludge production at fewer reagents dosage (Fe2+ dosage 798 mg/L and H2O2 dosage 2098 mg/L). The lesser sludge production reduces secondary environmental pollution, and low reagents dosage makes the process cost-effective. The optimization conditions were obtained by response surface methodology (RSM), and high coefficient of determination (R2 > 0.95) values confirm the adequacy of the models obtained. Furthermore, few experiments were performed on the sludge reusability, and valuable remarks were highlighted. Overall, the purpose of this study is to enhance the CFP's performance by overcoming its drawbacks.

Development of nodal diffusion code RAST-V for Vodo–Vodyanoi Energetichesky reactor analysis

This paper presents the development of a nodal diffusion code, RAST-V, and its verification and validation for VVER (vodo–vodyanoi energetichesky reactor) analysis. A VVER analytic solver has been implemented in an in-house nodal diffusion code, RAST-K. The new RAST-K version, RAST-V, uses the triangle-based polynomial expansion nodal method. The RAST-K code provides stand-alone and two-step computation modes for steady-state and transient calculations. An in-house lattice code (STREAM) with updated features for VVER analysis is also utilized in the two-step method for cross-section generation. To assess the calculation capability of the formulated analysis module, various verification and validation studies have been performed with Rostov-II, and X2 multicycles, Novovoronezh-4, and the Atomic Energy Research benchmarks. In comparing the multicycle operation, rod worth, and integrated temperature coefficients, RAST-V is found to agree with measurements with high accuracy which RMS differences of each cycle are within ±47 ppm in multicycle operations, and ±81 pcm of the rod worth of the X2 reactor. Transient calculations were also performed considering two different rod ejection scenarios. The accuracy of RAST-V was observed to be comparable to that of conventional nodal diffusion codes (DYN3D, BIPR8, and PARCS).

A new approach for daily life Blood-Pressure estimation using smart watch

Hypertension has become a major factor affecting people’s health. Timely monitoring and prevention of hypertension are of great significance. Most blood-pressure monitoring devices have redundant accessories and complex operations, which are not suitable for daily life applications. To solve these problems, we designed an application-level smart watch that can calculate the PAT feature using simultaneously collected ECG and PPG signals. By fusing the time–frequency-domain features of PPG and the correlation matrix between pulses, the information related to blood pressure in physiological signals was comprehensively extracted. Most of unstable signal segments can be eliminated and the impact of signal disturbances on overall accuracy will be reduced. This paper proposed two blood-pressure estimation modes: a two-step calib-free mode and a personal calibration mode based on transfer learning. The results on our self-established dataset (36 normotensive subjects and 40 hypertensive subjects) indicated that the two-step calib-free mode could estimate blood pressure with accuracy of 0.23 ± 6.1 mmHg and 0.63 ± 9.35 mmHg for DBP and SBP respectively, which was better than previous calib-free methods. Through the personal calibration mode, the estimation accuracy reached 0.02 ± 5.94 mmHg for DBP and 0.3 ± 7.69 mmHg for SBP, which complied with the Association for the Advancement of Medical Instrumentation standard.

Covalent organic framework based WO3@COF/rGO for efficient visible-light-driven H2 evolution by two-step separation mode

Covalent organic framework based Z-scheme heterostructure for efficient visible-light-driven hydrogen evolution. • A WO 3 @TpPa-1-COF core–shell Z-scheme heterojunction was firstly reported. • Bulk WO 3 was etched into ultra-small nanostructurer in the synthesis of composite. • WO 3 @TpPa-1-COF/rGO(30%) exhibits a high H 2 evolution rate of 26.73 mmol·g −1 ·h −1 . • The rGO facilitates the separation of charge carriers in the Z-scheme heterojunction. Covalent organic frameworks (COFs) are a new type of visible-light-driven photocatalysts, while effectively improving the separation and transfer of light-induced charges is of the key point to further enhance their activity. In this work, a new COF-based core–shell Z-scheme heterojunction WO 3 @TpPa-1-COF was firstly synthesized by in-situ etching bulk WO 3 into ultra-small nanostructure. Further, a ternary WO 3 @TpPa-1-COF/rGO composite with rGO attached on the surface of TpPa-1-COF was prepared by a facile one-pot photoreduction of GO solution containing as-synthesized WO 3 @TpPa-1-COF. The results of photocatalytic measurements show that the WO 3 @TpPa-1-COF/rGO(30%) composite material possesses a hydrogen evolution rate of 26.73 mmol·g −1 ·h −1 under visible-light irradiation, which is 11.73 and 1.6 times higher than that of TpPa-1-COF and WO 3 @TpPa-1-COF, respectively. Further study demonstrate a Z-Scheme charge transfer pathway exists in WO 3 @TpPa-1-COF/rGO composite which promote the separation of photogenerated charge carriers from COF, while the rGO attached on COF serves as electron collector in photocatalytic process further facilitating the transfer of photogenerated electrons to active sites. The reported strategy of building core–shell COF-base heterostructure and the resulting architecture with rGO as electron collector in Z-Scheme for facilitating the separation and transfer of charge carriers may open a new way for the design of highly efficient photocatalysts.

In situ observation of the electrochemical lithiation of a single MnO@C nanorod electrode with core/shell structure.

Transition metal oxides (TMOs) play a crucial role in lithium-ion batteries (LIBs) due to their high theoretical capacity, natural abundance, and benign environmental impact, but they suffer from limitations such as cyclability and high-rate discharge ability. One leading cause is the lithiation-induced volume expansion (LIVE) for "conversion"-type TMOs, which can result in high stress, fracture and pulverization. Using carbon layers is an effective strategy to provide effective volumetric accommodation for lithium-ion (Li+) insertion; however, the detailed mechanism is unknown. In order to clarify the working mechanism of nanoscale LIBs, herein, the discharge reactions in a nanoscale LIB were investigated through in situ environmental transmission electron microscopy (ETEM). Visualization of the Li+ insertion process of MnO@C nanorods (NRs) with core/shell structure (CSS) and internal void space (IVS) was achieved. The LIVE occurred in a consecutive two-step mode, i.e., a LIVE of the carbon layer followed by a co-LIVE of the carbon layer and MnO. No volume contraction of the IVS was observed. The IVS acted as a buffer relieving the stress of the carbon layer. The carbon layer with IVS simultaneously improved the cyclability and the high-rate discharge ability of the electrode, pointing to a promising route for building better TMO electrode materials.

Quality analysis of CMT lap welding based on welding electronic parameters and welding sound

Monitoring of weld joint quality is a significant issue in Cold Metal Transfer (CMT) lap welding. In this paper, CMT lap welding experiment of low carbon steel sheet was carried out, the sound characteristics of CMT are studied. Further analysis of the “special two-step mode” of welding sound shows that the faster the change of arc energy, the greater the corresponding sound pressure value. Furthermore, the feature extraction and fusion methods of welding electrical parameters and welding sound signals were investigated based on the two abnormal welding states: gas feeding error and welding wear. In the aspect of electric signal, welding current, welding voltage, line energy were studied, and in the aspect of sound signal, MFCC is extracted after de-framing and windowing. BiLSTM-CTC algorithm has been used to identify welding process gas feeding error and welding wear. For the recognition model the classification error rate based on sound feature is the lowest at 0.389, and the classification error rate based on electrical signal and acoustic signal fusion feature is at 0.295.

Preparation of Transparent MgAl2O4 Spinel by Pulsed Electric Current Sintering Using Two-step Heating Method

Transparent MgAl2O4 ceramics were fabricated by pulsed electric current sintering (PECS) employing two-step sintering mode. First, nanoscale MgAl2O4 powders were produced by solution combustion synthesis from hydrated nitrate compounds and urea. Subsequently, the synthesized powders were sintered by PECS with a heating rate of 100oC/min under an applied pressure of 100 MPa. The sintering process was conducted according to two-step heating profile. At the first step, the temperature increased to 1050, 1100, and 1150oC, followed by a dwell time of 60 min. The second-step sintering was carried out at 1300, 1350, and 1400oC for 20 min. The transparent ceramics sintered at 1050oC/ 60 min – 1400oC/ 20 min exhibited transmittance over 80% in infrared range. In addition, transparent samples presented a Vickers hardness up to 30 GPa for sintering mode of 1150oC/ 60 min – 1400oC/ 20 min.

Implementation of in vitro glycoengineering of monoclonal antibodies into downstream processing of industrial production.

In vitro glycoengineering using exoenzymes for specific modification is recognized as appropriate method to tailor sugar moieties of glycan structures during the recombinant production of monoclonal antibodies (mAbs). This report describes enhanced in vitro glycoengineering approaches using β1,4-galactosyltransferase and α2,6-sialyltransferase to improve the efficiency of galactosylation and sialylation with the aim to implement in vitro glycoengineering into common mAb purification processes. Feasibility studies tested the potential of different in vitro glycoengineering protocols (two-step vs. one-step) to facilitate the overall procedure. Scalability of the reactions was demonstrated for mAb amounts ranging from 1mg to 1g. Additionally, the reactions of β1,4-galactosyltransferase and α2,6-sialyltransferase were shown to work on column during affinity chromatography using Protein A or KappaSelect, the latter providing more efficient galactosylation and sialylation of IgG1 and IgG4 mAbs. Performing in vitro glycoengineering on column enabled the use of cell culture harvest that yielded results comparable to those of purified bulk. Based thereon, an optimized two-step mixed mode approach was found most appropriate to integrate in vitro glycoengineering of the IgG1 mAb into the overall manufacturing process. Using harvest for on-column reaction of β1,4-galactosyltransferase combined with in-solution reaction of α2,6-sialyltransferase, this approach yielded 100% biantennary galactosylation and 61% biantennary sialylation. Moreover, the enzymes applied in in vitro glycoengineering could be separated, recycled and reused in further reactions to improve economic efficiency. Overall, the study provides a toolbox for in vitro glycoengineering and presents an optimized easy-to-handle workflow to implement this method into the downstream processing of industrial mAb production.

Applications of one-Step environmentally-friendly fermentation method to produce fumaric acid with immobilized Rhizopus arrhizus in stirred-tank reactor

The traditional two-step cultivation mode for fungal cultivation is commonly divided into the seed stage (usually 24 to 48 h) and the production stage (usually 96 to 144 h). The use of two stages prolongs the total production cycle and generates excess wastewater. In this work, an efficient and environmentally friendly one-step fermentation method was applied for the production of fumaric acid by immobilized Rhizopus arrhizus in a stirred-tank reactor. The nitrogen source content and the agitation speed of the reactor were optimized as the two critical factors in the one-step fermentation process; the fumaric acid production of 51 g/L with a yield of 0.42 g/g glucose was comparable with the product from the traditional two-step fermentation process. Furthermore, the total production cycle was shortened to 96 h, and the amount of wastewater was reduced due to the avoidance of the seed culture process. Thus, utilization of the one-step fermentation method to produce fumaric acid was shown to be preferable feasibility and environmental-friendliness. This is a promising method for industrial production of fumaric acid and other high-value biochemicals by fungus.

PSIC-Net: Pixel-Wise Segmentation and Image-Wise Classification Network for Surface Defects

Recent years have witnessed the widespread research of the surface defect detection technology based on machine vision, which has spawned various effective detection methods. In particular, the rise of deep learning has allowed the surface defect detection technology to develop further. However, these methods based on deep learning still have some drawbacks. For example, the size of the sample data is not large enough to support deep learning; the location and recognition of surface defects are not accurate enough; the real-time performance of segmentation and classification is not satisfactory. In the context, this paper proposes an end-to-end convolutional neural network model: the pixel-wise segmentation and image-wise classification network (PSIC-Net). With the innovative design of a three-stage network structure, improved loss function and a two-step training mode, PSIC-Net can accurately and quickly segment and classify surface defects with a small dataset of training data. This model was evaluated with three public datasets, and compared with the most advanced defect detection methods. All the performance metrics prove the effectiveness and advancement of PSIC-Net.

Cascade temperature-arising strategy for xylo-oligosaccharide production from lignocellulosic biomass with acetic acid catalyst recycling operation

Acetic acid acidolysis had so far been performed as a green technology to produce high value-added xylo-oligosaccharide from lignocellulosic residues while around 30% inert xylan-constitute is still retained. For improving economic and environmental benefits, a cascade temperature-arising technical strategy was designed and developed for the co-production of xylo-oligosaccharide and enzymatic-hydrolyzed glucose by a continuous two-step acidolysis mode with the recyclable acetic acid catalyst. The combined process was optimized by uniform design experiments and temperature plays the key factor for xylo-oligosaccharide yield and xylose-chemicals degradation. We obtained respectively 63.41% and 61.44% xylo-oligosaccharide yield from corncob and wheat straw during continuous two-step acidolysis with acetic acid recycling operation at 140 °C and 190 °C, which increased by 52.03% and 76.55% than the one-step process. Meanwhile, the corresponding enzymatic hydrolysis yield was increased to 100% and 98.2%. In short, the two-step cascade temperature-rising acidolysis technology can maximize the utilization of hemicellulose and cellulose constitutes and fully explore the value-added utilization of lignocellulosic biomass. The cascade temperature-arising technical strategy does therefore demonstrate something for the more efficient and green utilization of lignocellulosic biomass.

Retail dynamic pricing strategy design considering the fluctuations in day-ahead market using integrated demand response

The imbalance between fixed retail prices and fluctuating wholesale prices imposes enormous stresses on the profits of residential retailers. Dynamic pricing (DP) can be regarded as an effective measure for retailers to motivate demand resources and reduce their market risks. However, existing DP programs cannot be adapted to all residents, as these programs can bring financial risk to some groups, influencing their marketability to some extent. In this study, a DP model is proposed considering the fluctuation in the day-ahead market from the view of retailers. This model consists of two parts: (i) the fixed price, representing the existing price, and (ii) the floating price, which is a real-time reflection of the fluctuating day-ahead price. Then, a two-step settlement mode is adopted for this DP to ensure that there is no expenditure supplement of residents compared with the existing price. Further, in a community energy system, an integrated demand response strategy for profit maximization of the retailer is proposed to determine the optimal DP, in which the response behavior of residents is established using the demand price elasticity matrix on the whole. A detailed case study is conducted in three price scenarios to verify its applicability and effectiveness. The results show that DP strategies are beneficial for both the retailer and all residents. In addition, this approach can benefit residents who use more energy in valley hours but less energy during peak hours.

Advantages of continuous Fenton reaction over the traditional batch process in wastewater treatment in a single and two-step mode

Advantages of continuous Fenton reaction over the traditional batch process in wastewater treatment in a single and two-step mode

Two-Step Adaptive Chirp Mode Decomposition for Time-Varying Bearing Fault Diagnosis

Fault diagnosis of rolling bearing has always been the focus of research in the engineering field. Due to the nonstationary conditions, this work has suffered huge challenges. The adaptive chirp mode decomposition (ACMD) is a signal decomposition method developed recently. By using a recursive framework embedded with an iterative algorithm, it can decompose signals one by one. Although this scheme has strong adaptability, the accuracy of reconstructed signals is very rough. Moreover, the estimated components will even deviate from the true results as the iteration progresses when two components are very close. In order to solve the above problems, a novel two-step ACMD is proposed in this article. Specifically, the recursive scheme without an iterative algorithm is only used to decompose signals first, which can determine the number of components. Then, the joint-estimation framework using an iterative algorithm is used to achieve high-resolution component reconstruction. The main idea of this two-step method is to let different schemes do what they do best. Subsequently, we proposed a new fault diagnosis method for rolling bearing under variable speeds based on the proposed two-step ACMD. Finally, both simulation and actual bearing diagnosis cases verify the potential of the proposed method and successfully diagnosed different kinds of rolling bearing faults.

Kinetics-Limited Two-Step Growth of van der Waals Puckered Honeycomb Sb Monolayer.

Puckered honeycomb Sb monolayer, the structural analog of black phosphorene, has been recently successfully grown by means of molecular beam epitaxy. However, little is known to date about the growth mechanism for such a puckered honeycomb monolayer. In this study, by using scanning tunneling microscopy in combination with first-principles density functional theory calculations, we unveil that the puckered honeycomb Sb monolayer takes a kinetics-limited two-step growth mode. As the coverage of Sb increases, the Sb atoms first form the distorted hexagonal lattice as the half layer, and then the distorted hexagonal half-layer transforms into the puckered honeycomb lattice as the full layer. These results provide the atomic-scale insight in understanding the growth mechanism of puckered honeycomb monolayer and can be instructive to the direct growth of other monolayers with the same structure.

Prediction With Multicross Component for Future Video Coding

There has been a consensus of cross-component prediction in video compression that the interchannel redundancies can be effectively removed through a linear prediction model. To fully explore the similarities existing in different color components, we propose prediction with multicross component (PMC) as a new chroma intracoding mode for the emerging video coding standard AVS3. The proposed PMC enjoys extremely low operational complexity and high flexibility, which advocates to reuse and reform the linear prediction model of conventional two-step cross-component prediction mode. Moreover, dual-prediction patterns of PMC are exploited to enhance the prediction efficiency. Experimental results on AVS3 test model HPM-6.0 show that PMC brings 0.32%, 1.60%, and 2.39% BD-rate savings for Y, Cb, and Cr components, respectively, under all intraconfiguration with natural-scene videos. Moreover, 0.91%, 2.24%, and 2.82% BD-rate gains can be observed on screen-content videos. Subset modes of PMC have been adopted by AVS3.

Magnetoelectric Effect in Two-Layer Composites with a Graded Magnetic Phase

Samples of a homogeneous (x = 0, 0.1, and 0.2) and multilayer ceramics with a gradient composition (x = 0.2 → 0.1 → 0 → 0.1 → 0.2) based on solid solutions of (Ni1 − xZnx)Fe2O4 nickel–zinc ferrites have been manufactured using the thick-film technology. After sintering in a two-step mode, the gradient samples exhibited a smooth non-uniform distribution of chemical elements (Zn, Ni) over the thickness. The longitudinal (αE33) and transverse (αE31) magnetoelectric effects in two-layer PZT–nickel ferrite composites have been studied. In the absence of an external magnetostatic field, the values of magnetoelectric coefficients were negligible. The maximum value of the longitudinal magnetoelectric coefficient for composites with the gradient magnetic phase was practically two times higher than value of αE33 for homogeneous structures.

Bioprocessing of spent lithium ion batteries for critical metals recovery – A review

The increasing demand for metals and the concomitant depletion of the primary metallic resources is one of the most important environmental and societal challenges nowadays. Critical metals, rare earth elements, base and precious metals demand is growing day-by-day and driving many metals towards the edge of supply risk. On the other hand, the problems linked to waste generation (especially waste electrical and electronic equipment (WEEE)) are also increasing globally. These end-of-life electronic wastes contain significant concentration of critical raw materials accompanied by harmful substances. Spent Li ion batteries is a kind of WEEE stream, bearing considerable concentrations of valuable metals (like Co, Li, Mn and Ni). If the end-of-life Li ion batteries are not managed properly, there is a high risk that these valuable metals and toxic substances could end into the environment. In order to address the environmental complications, sustainable resource management and boost circular economy, it is important to properly manage and recycle these spent Li ionbatteries. Conventional methods based on high-temperature pyro-metallurgical routes together with hydro-metallurgical processing have been widely studied for the recovery of metals from spent LiBs. However, bio-metallurgical approaches have an edge over their counter parts because of their environmentally friendly nature. Microbe-metal interactions have received special attention both in terms of leaching metals from WEEE and also in recovering metal ions from aqueous streams. Microbial technologies are promising for removing metal ions because of less cost, technical feasibility for large scale applications and no need for addition of toxic chemicals thereby avoiding generation of toxic or hazardous byproducts. In this study, particular emphasis is placed on reviewing the progress made in biohydrometallurgy (i.e. bacterial and fungal leaching practices as one and two-step mode) for the leaching of critical metals from waste lithium ion batteries. Biotechnological methods (e.g. biosorption, bioprecipitation and bioelectrochemical treatment) for the recovery of critical metals from pregnant leachates and aqueous streams are also discussed.

Piezoelectric inertial rotary actuator operating in two-step motion mode for eliminating backward motion

The backward motion phenomenon is widespread in inertial impact, stick-slip, and parasitic piezoelectric actuators, and seriously limits the development of these actuators for micro-manipulation applications. To solve this problem, a piezoelectric inertial rotary actuator based on a special wiring scheme is proposed. By changing the pair of piezoelectric vibrators in the traditional actuator to have opposite connection modes, the proposed actuator implements a two-step operating mode over one cycle and suffers no backward motion. Thus, the proposed actuator essentially eliminates the backward motion phenomenon under all conditions. Compared with other methods for controlling backward motion, which typically require additional friction-control or complex signal-control systems, the proposed wiring method has the advantages of simplicity of structure, ease of control, and high stability.