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Acid fracturing is a technique to enhance productivity in carbonate formations. In this work, a thermal–hydraulic–mechanical–chemical (THMC) coupling model for acid fracture propagation is proposed based on a phase-field approach. The phase-field variable is utilized as an indicator function to distinguish the fracture and the reservoir, and to track the propagation of the fracture. The resulting system is a nonstationary, nonlinear, variational inequality system in which five different physical modules for the displacement, the phase-field, the pressure, the temperature, and the acid concentration are coupled. This multi-physical system includes numerical challenges in terms of nonlinearities, solution coupling algorithms, and computational cost. To this end, high fidelity physics-based discretizations, parallel solvers, and mesh adaptivity techniques are required. The model solves the phase-field and the displacement variables by a quasi-monolithic scheme and the other variables by a partitioned schemes, where the resulting overall algorithm is of iterative coupling type. In order to maintain the computational cost low, the adaptive mesh refinement technique in terms of a predictor-corrector method is employed. The error indicators are obtained from both the phase-field and concentration approximations. The proposed model and the computational robustness were investigated by studying fourteen cases as well as some mesh refinement studies. It is observed that the acid and thermal effect increase the fracture volume and fracture width. Moreover, the natural fractures and holes affect the acid fracture propagation direction. Highlights: thermal–hydraulic–mechanical–chemical coupling system was established for acid fracture propagation based on a phase-field method. The acid fluid equations including diffusion, transport and reaction were derived. The penalization method was introduced based on physical reality. Acid fracture problem is a kind of dynamic heterogeneous problem. The adaptive mesh refinement was extended to help researchers get smooth simulation results and save computation costs. [ABSTRACT FROM AUTHOR]

The synthesis of high‐entropy alloys (HEAs) with ultra‐small particle sizes has long been a challenging task. The complex and time‐consuming synthesis process hinders their practical application and widespread adoption. This study presents the novel synthesis of TiO2 nanoparticles loaded with a quinary high‐entropy alloy through flame spray pyrolysis (FSP) for the first time. The extremely fast heating rate of flame combustion makes the precursor fast pyrolysis gasification, high temperature in the flame field promotes the metal vapor mixing uniformly, and the fast quenching process can reduce the particle aggregation sintering, the ultra‐small particle size of HEA firmly attached to the TiO2 surface. The catalysts prepared via this gas‐to‐particle pathway exhibit excellent performance in CO2 hydrogenation, achieving a conversion rate of 62% at 450 °C, and maintaining their activity for over 220 h without significant particle agglomeration. This finding provides valuable insights for the future design of catalytically active materials with enhanced activity and long‐term stability. [ABSTRACT FROM AUTHOR]

Optical Music Recognition (OMR) is an important way to digitize score images and has broad application prospects in fields such as the storage of music documents, music education and digital creation. As a new paradigm for object detection, DETR (detection transformer) has the ability to associate contextual information, which can be exploited to resolve the OMR task. However, the original DETR does not fit OMR well due to its high computational complexity and numerous parameters. To address the DETR defects and improve the recognition accuracy of OMR, we propose a novel multi-scale DETR (M-DETR) with a multi-scale feature fusion mechanism and improved attention mechanisms. First, a new multi-scale feature fusion mechanism is designed to let the backbone network of M-DETR get rich multi-scale information. Then, a key-region attention mechanism is incorporated based on the character that the key information is concentrated on a score image. Finally, the pre-context attention mechanism is introduced to make better use of the contextual association between recognition notes in music scores. Experiment results show that M-DETR achieves recognition accuracy of 90.6% for 7 typical small-sized notes, which is better than Faster R-CNN and YOLO v5, and the improvement rate is 10.02% compared to the original DETR algorithm. The results indicate that M-DETR is an effective way for the OMR task, which also provides a new solution for the detection of small-sized objects with contextual association. • A backbone network with a feature fusion mechanism. • A key-region attention mechanism on the information of the head regions. • A pre-context attention mechanism with correlation among the targets in music scores. • A novel M-DETR algorithm to improve the recognition accuracy for OMR. [ABSTRACT FROM AUTHOR]

Polycrystalline Al workpieces go through a complex surface atom sputtering and surface/subsurface atom diffusion throughout the ion beam machining process that plays a critical role in determining machining quality of optical mirror surfaces. Here, we leverage molecular dynamics method for the first time to reveal the machining mechanism and the polycrystalline effect of aluminum during ion beam sputtering, in term of cascade collision, atom trajectory, sputtering yield, and surface characteristic. Polycrystalline Al presents a significant low potential energy state, leading to milder cascade collision and weaker sputtering effects than monocrystalline Al during ion beam machining. The atom trajectory demonstrates irregular variation as the atom diffusion is blocked by grain boundary (GB) in polycrystalline Al, leading to the relief microstructure and poor surface quality. With incident ions increasing, the GBs are broken and atom diffusion enhancing, as well as lower subsurface defects and better finishing surface quality. The microscopic morphology evolves into gravel microstructure. Simulation results also reveal that atom diffusion will benefit from high ion concentration and low ion energy. Sputtering yield variation is more sensitive to ion energy. To acquiring better finishing surface quality of Al without influencing machining efficiency, ion concentration must be increased while the ion energy needs to be decreased appropriately but a large number of cascading collisions need to be ensured. • The machining mechanism and polycrystalline effect of Al during ion beam sputtering are investigated via molecular dynamics simulation. • Cascade collision is milder in polycrystalline Al, and atom trajectory demonstrates irregular variation as the atom diffusion blocked by grain boundary. • Impeding effect of grain boundaries induces the relief microstructure. With incident ions increasing, the grain boundaries are broken, and the gravel structure dominates the surface morphology. • Lower ion energy and higher ion concentration will benefit atomic diffusion, inducing a better finishing surface roughness. [ABSTRACT FROM AUTHOR]

Carbon market is the most effective market tool for carbon emission reduction. China, the largest carbon emitter in the world, established the national carbon market in 2021, covering over 2000 key units in the power sector. Therefore, the forecasting of carbon price has profound implications for environmental and energy policies. In this paper, two traditional econometric model and three kinds of machine learning (ML) algorithms are used to predict carbon returns in the Chinese carbon trading market based on carefully selected predictors. Among all forecasting models, the Random Forest (RF) has the best forecasting performance, followed by some GARCH models using various factors. Compared with the traditional benchmark of ARMA model, the BP neural network (BP) and the GA improved BP method (GA-BP) are less competitive in predicting carbon returns in China because of their large forecasting errors. According to the optimal model, social attention to the carbon market, the international crude oil returns and the overall performance of the stock market are the most important predictors. The findings are robust to the change in the sample set. Overall, the ML approach shows an advantage in forecasting carbon returns, but the selection of predictors is also important. • Machine learning and econometric models are used to forecast carbon returns in China. • The selection of predictors is based on economic analysis. • The Random Forest (RF) outperforms the other ML and econometric methods. • The energy market is extremely important for predicting carbon returns. • Social concerns and stock market performance improve forecasting accuracy. [ABSTRACT FROM AUTHOR]

Table 1 contains crystallographic data and Table 2 contains the list of the atoms including atomic coordinates and displacement parameters. Generally, the 1,5-dione molecules were achieved by the Aldol and Michael addition cascade reactions using the inorganic and organic base as catalysts and the preparation of 1,5-dione derivatives has received considerable attention because they could facilitate the efficient construction of complex bioactive molecules in an atom/step economic manner [[5]]. [Extracted from the article]

The surface quality and subsurface damage (SSD) distribution achieved with a fine-grained grinding wheel under different depth-of-cut and cutting speed is experimentally studied. The ground surface roughness (SR) is investigated via white light interferometry and expressed in terms of four typical roughness values (PV, RMS, Rz, and Ra). The SSD is characterized by the magnetorheological finishing (MRF) spot method and transmission electron microscopy. The results show that brittle-ductile surfaces and ductile-like surfaces are generated during ultra-precision grinding. Largely due to plastic flow removal, fracture defects such as fractured pits and grinding streaks on the ground surface can be mitigated. Instead, a ductile-like surface covered with grinding streaks is found. When the depth-of-cut decreases from 4 to 1 μm, the SR and SSD depth decreases from PV 1.34 μm, Ra 15.23 nm, Rz 0.94 μm, RMS 22.24 nm, and SSD 6.1 μm to PV 0.51 μm, Ra 5.07 nm, Rz 0.24 μm, RMS 6.70 nm, and SSD 1.2 μm. In addition, when the cutting speed increases from 3.9 to 23.4 m/s, the SR and SSD depth decreases from PV 1.03 μm, Ra 15.01 nm, Rz 0.82 μm, RMS 21.43 nm, and SSD 5.6 μm to PV 0.12 μm, Ra 3.17 nm, Rz 0.07 μm, RMS 4.65 nm, and SSD 0.003 μm. Moreover, the material removal mechanism under different grinding parameters is revealed by calculating undeformed chip thickness, and the mechanism of surface morphology and subsurface crack produced in brittle-ductile mode is analyzed. A linear relationship between the SR and SSD depth is in accord with the formula SSD = 0.41Ra−0.68 for brittle-ductile surfaces. [ABSTRACT FROM AUTHOR]

Steering acid fracturing is a technique that improves the conductivity of carbonate reservoir. It is widely used in a carbonate reservoir. However, due to the lack of comparative experiments, the application of steering acid to improve the fracturing results is still unknown. Therefore, a series of true triaxial acid fracturing experiments were conducted to study steering acid fracturing in carbonate reservoir. The carbonate specimens used in the experiment were from the Qixia group and Dengsi Member in Sichuan, China. In this study, slick water, cross-linked gel, and self-generating acid were used as ahead fluid to cooperate with steering acid. Experimental results show that (1) the low-viscosity ahead fluid with steering acid can result in more complex fractures; (2) the complexity of fractures is influenced by natural fracture and the viscosity of the ahead fluid; and (3) based on the 3D scanning results of the fracture surface, different ahead fluids will lead to different corrosion results. This study provides useful suggestions on steering acid fracturing design and physical simulation experiments. [ABSTRACT FROM AUTHOR]

Recent advances in CRISPR based biotechnologies have greatly expanded our capabilities to repurpose CRISPR for the development of biomolecular sensors for diagnosing diseases and understanding cellular pathways. The key attribute that allows CRISPR to be widely utilized is the programmable and highly selective mechanism. In this Minireview, we first illustrate the molecular principle of CRISPR functioning process from sensing to actuating. Next, the CRISPR based biosensing strategies for nucleic acids, proteins and small molecules are summarized. We highlight some of recent advances in applications for in vitro detection of biomolecules and in vivo imaging of cellular networks. Finally, the challenges with, and exciting prospects of, CRISPR based biosensing developments are discussed. [ABSTRACT FROM AUTHOR]

Recent advances in CRISPR based biotechnologies have greatly expanded our capabilities to repurpose CRISPR for the development of biomolecular sensors for diagnosing diseases and understanding cellular pathways. The key attribute that allows CRISPR to be widely utilized is the programmable and highly selective mechanism. In this Minireview, we first illustrate the molecular principle of CRISPR functioning process from sensing to actuating. Next, the CRISPR based biosensing strategies for nucleic acids, proteins and small molecules are summarized. We highlight some of recent advances in applications for in vitro detection of biomolecules and in vivo imaging of cellular networks. Finally, the challenges with, and exciting prospects of, CRISPR based biosensing developments are discussed. [ABSTRACT FROM AUTHOR]

Modular construction of an autonomous and programmable multi‐functional heterogeneous biochemical circuit that can identify, transform, translate, and amplify biological signals into physicochemical signals based on logic design principles can be a powerful means for the development of a variety of biotechnologies. To explore the conceptual validity, we design a CRISPR‐array‐mediated primer‐exchange‐reaction‐based biochemical circuit cascade, which probes a specific biomolecular input, transform the input into a structurally accessible form for circuit wiring, translate the input information into an arbitrary sequence, and finally amplify the prescribed sequence through autonomous formation of a signaling concatemer. This upstream biochemical circuit is further wired with a downstream electrochemical interface, delivering an integrated bioanalytical platform. We program this platform to directly analyze the genome of SARS‐CoV‐2 in human cell lysate, demonstrating the capability and the utility of this unique integrated system. [ABSTRACT FROM AUTHOR]

Modular construction of an autonomous and programmable multi‐functional heterogeneous biochemical circuit that can identify, transform, translate, and amplify biological signals into physicochemical signals based on logic design principles can be a powerful means for the development of a variety of biotechnologies. To explore the conceptual validity, we design a CRISPR‐array‐mediated primer‐exchange‐reaction‐based biochemical circuit cascade, which probes a specific biomolecular input, transform the input into a structurally accessible form for circuit wiring, translate the input information into an arbitrary sequence, and finally amplify the prescribed sequence through autonomous formation of a signaling concatemer. This upstream biochemical circuit is further wired with a downstream electrochemical interface, delivering an integrated bioanalytical platform. We program this platform to directly analyze the genome of SARS‐CoV‐2 in human cell lysate, demonstrating the capability and the utility of this unique integrated system. [ABSTRACT FROM AUTHOR]

DNA has many unique properties beyond encoding genetic information, one of which is its physicochemical stability based on Watson–Crick base pairing. Differences in sequence complementarity between multiple DNA strands can lead to the strand displacement reaction (SDR). SDRs have been regularly applied in synthetic biology, drug delivery, and, importantly, biosensing. SDR-based biosensors have high controllability, high sensitivity, and low interference, and can be used for multiplexed detection. Such biosensors have been demonstrated to detect nearly every class of biomolecule. As the field continues to mature, such platforms can be used as an integral tool for the manipulation of biomolecular reactions, bringing biosensors one step closer to the ultimate goal of point-of-care systems. SDRs directly connect a biosensing recognition event to its signaling event, producing simple, integrated platforms. Combining SDRs into cascades provides inherent amplification of target signals, thus boosting the sensitivity of the biosensing system. The incorporation of orthogonal strand displacement cascades allows multiplexed detection of multiple targets in one sample. SDRs can be applied universally to a diverse type of targets, including nucleic acids, proteins, and small molecules. [ABSTRACT FROM AUTHOR]

An accurate, rapid, and cost‐effective biosensor for the quantification of disease biomarkers is vital for the development of early‐diagnostic point‐of‐care systems. The recent discovery of the trans‐cleavage property of CRISPR type V effectors makes CRISPR a potential high‐accuracy bio‐recognition tool. Herein, a CRISPR‐Cas12a (cpf1) based electrochemical biosensor (E‐CRISPR) is reported, which is more cost‐effective and portable than optical‐transduction‐based biosensors. Through optimizing the in vitro trans‐cleavage activity of Cas12a, E‐CRIPSR was used to detect viral nucleic acids, including human papillomavirus 16 (HPV‐16) and parvovirus B19 (PB‐19), with a picomolar sensitivity. An aptamer‐based E‐CRISPR cascade was further designed for the detection of transforming growth factor β1 (TGF‐β1) protein in clinical samples. As demonstrated, E‐CRISPR could enable the development of portable, accurate, and cost‐effective point‐of‐care diagnostic systems. [ABSTRACT FROM AUTHOR]

An accurate, rapid, and cost‐effective biosensor for the quantification of disease biomarkers is vital for the development of early‐diagnostic point‐of‐care systems. The recent discovery of the trans‐cleavage property of CRISPR type V effectors makes CRISPR a potential high‐accuracy bio‐recognition tool. Herein, a CRISPR‐Cas12a (cpf1) based electrochemical biosensor (E‐CRISPR) is reported, which is more cost‐effective and portable than optical‐transduction‐based biosensors. Through optimizing the in vitro trans‐cleavage activity of Cas12a, E‐CRIPSR was used to detect viral nucleic acids, including human papillomavirus 16 (HPV‐16) and parvovirus B19 (PB‐19), with a picomolar sensitivity. An aptamer‐based E‐CRISPR cascade was further designed for the detection of transforming growth factor β1 (TGF‐β1) protein in clinical samples. As demonstrated, E‐CRISPR could enable the development of portable, accurate, and cost‐effective point‐of‐care diagnostic systems. [ABSTRACT FROM AUTHOR]

A number of very recently developed electrochemical biosensing strategies are promoting electrochemical biosensing systems into practical point‐of‐care applications. The focus of research endeavors has transferred from detection of a specific analyte to the development of general biosensing strategies that can be applied for a single category of analytes, such as nucleic acids, proteins, and cells. In this Minireview, recent cutting‐edge research on electrochemical biosensing strategies are described. These developments resolved critical challenges regarding the application of electrochemical biosensors to practical point‐of‐care systems, such as rapid readout, simple biosensor fabrication method, ultra‐high detection sensitivity, direct analysis in a complex biological matrix, and multiplexed target analysis. This Minireview provides general guidelines both for scientists in the biosensing research community and for the biosensor industry on development of point‐of‐care system, benefiting global healthcare. [ABSTRACT FROM AUTHOR]

A number of very recently developed electrochemical biosensing strategies are promoting electrochemical biosensing systems into practical point‐of‐care applications. The focus of research endeavors has transferred from detection of a specific analyte to the development of general biosensing strategies that can be applied for a single category of analytes, such as nucleic acids, proteins, and cells. In this Minireview, recent cutting‐edge research on electrochemical biosensing strategies are described. These developments resolved critical challenges regarding the application of electrochemical biosensors to practical point‐of‐care systems, such as rapid readout, simple biosensor fabrication method, ultra‐high detection sensitivity, direct analysis in a complex biological matrix, and multiplexed target analysis. This Minireview provides general guidelines both for scientists in the biosensing research community and for the biosensor industry on development of point‐of‐care system, benefiting global healthcare. [ABSTRACT FROM AUTHOR]

• MnO 2 structures affected activation of peroxymonosulfate for BPA degradation. • Three crystalline MnO 2 were more reactive than less crystalline δ-MnO 2. • Reactivity of crystalline MnO 2 correlated with Mn AOS, Mn(III)%, and conductivity. • Direct oxidation by MnO 2 was important in BPA degradation in acidic conditions. • Both radical and non-radical mechanisms were involved in the catalytic oxidation. MnO 2 with various structures, including three tunnel structures (α-, β-, γ-MnO 2) and a layered structure (δ-MnO 2), were synthesized and investigated for peroxymonosulfate (PMS) activation. The effects of different structured MnO 2 on PMS activation in contaminant degradation, as quantified by the pseudo-first order rate constants of bisphenol A (BPA) oxidation, followed the order: α-MnO 2 > γ-MnO 2 > β-MnO 2 > δ-MnO 2. Results showed that under acidic conditions, BPA was degraded by both catalytic oxidation by PMS-MnO 2 and direct oxidation by MnO 2 , and the relative importance of the two mechanisms differed for different MnO 2. The direct oxidation accounted for 25.2, 7.4, 34.1, and 94.5% of the total reactivity of α-, β-, γ-, and δ-MnO 2 , respectively. Physicochemical properties of MnO 2 including crystal structure, morphology, surface Mn oxidation states, surface area, oxygen species and conductivity were characterized and correlated with the catalytic reactivity. The results demonstrated that the crystallinity of MnO 2 was the dominant factor in the catalytic reactivity, resulting in the lowest reactivity for the least crystalline δ-MnO 2. For the crystalline MnO 2 , the catalytic reactivity linearly correlated with Mn average oxidation state, Mn(III) content, and conductivity. Electron spin resonance (ESR) and quenching experiments with ethanol and tert -butanol suggested that sulfate radicals (SO 4 −) were the dominant radicals in the systems, while hydroxyl radicals (OH) played a minor role. In addition, nonradical mechanisms such as singlet oxygen (1O 2) also contributed to the BPA degradation, especially when δ-MnO 2 was the catalyst. These findings offered new insights into the contaminant degradation mechanisms in PMS-MnO 2 and provided guidance to develop cost-effective catalysts for water/wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract The analysis of protein-nucleic acid interactions is essential for biophysics related research. However, simple, rapid, and accurate methods for quantitative analysis of biomolecular interactions are lacking. We herein establish an electrochemical biosensor approach for protein-nucleic acid binding analysis. Nanoparticle based sensors are fabricated by highly-controlled inkjet printing followed by plasma conversion. A novel bioconjugation method is demonstrated as a simple and rapid approach for protein-based biosensor fabrication. As a proof of concept, we analyzed the binding interaction between unwinding protein 1 (UP1) and SL3ESS3 RNA, confirming the accuracy of this nanoparticle based electrochemical biosensor approach with traditional biophysical methods. We further accurately profiled and differentiated a unique binding interaction pattern of multiple G-tract nucleic acid sequences with heterogeneous nuclear ribonucleoprotein H1. Our study provides insights into a potentially universal platform for in vitro biomolecule interaction analysis using a nanoparticle based electrochemical biosensor approach. Graphical abstract fx1 Highlights • Simple, rapid, and accurate general electrochemical method for biomolecules binding affinity analysis. • Plasma produced gold nanoparticle sensor. • Detail analysis of G-tract nucleic acids interaction with heterogeneous nuclear ribonucleoprotein H1 (hnRNP H1). [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Different tunnel structured MnO 2 nanoparticles were synthesized and characterized. • The first investigation on the effect of tunnel structured MnO 2 on electrochemical oxidation of nitrite. • α-MnO 2 found to be the most reactive structure for electrochemical sensing. Abstract Three MnO 2 nanoparticles with different tunnel structures, α-, β-, and γ-MnO 2 , were synthesized and characterized. We demonstrated and compared their capabilities on the electrochemical oxidation of nitrite, providing a new perspective for MnO 2 or MnO 2 based materials on sensing application. α-MnO 2 exhibited higher electrochemical reactivity than β- or γ-MnO 2 , which was ascribed to its higher conductivity, more exposure to MnO 6 edges, longer average Mn O bond length, and lower Mn average oxidation state(AOS). We hereby reported the first α-MnO 2 nanoparticle-based electrochemical sensor for nitrite sensing. A highly controlled micro-plotter was used to deposit the MnO 2 nanoparticles for the sensor fabrication, providing a micro-pattern of the sensing surface area of MnO 2 and ensuring the reproducibility and sensitivity of this MnO 2 based sensor. Using differential pulse voltammetry, a detection range of 10–800 μM of nitrite was accomplished along with a sensitivity of 17.1 μA μM−1 and a detection limit of 0.5 μM. [ABSTRACT FROM AUTHOR]

A simple-prepare, single-use and cost-effective, in vitro biosensor for the detection of TAR DNA-binding protein 43 (TDP-43), a biomarker of neuro-degenerative disorders, was designed, manufactured and tested. This study reports the first biosensor application for the detection of TDP-43 using a novel biosensor fabrication methodology. Bioconjugation mechanism was applied by conjugating anti-TDP 43 with N-succinimidyl S-acetylthioacetate (SATA) producing a thiol-linked anti-TDP 43, which was used to directly link with gold electrode surface, minimizing the preparation steps for biosensor fabrication and simplifying the biosensor surface. The effectiveness of this bioconjugation mechanism was evaluated and confirmed by FqRRM12 protein, using nuclear magnetic resonance (NMR). The surface coverage of the electrode was analyzed by Time-of-Flight-Secondary Ion Mass Spectrometry (TOF-SIMS). Differential pulse voltammetry (DPV) was acted as the detection transduction mechanism with the use of [Fe(CN) 6 ] 3-/4- redox probe. Human TDP-43 peptide of 0.0005 µg/mL to 2 µg/mL in undiluted human serum was analyzed using this TDP-43 biosensor. Interference study of the TDP-43 biosensor using β-amyloid 42 protein and T-tau protein confirmed the specificity of this TDP-43 biosensor. This bioconjugation chemistry based approach for biosensor fabrication circumvents tedious gold surface modification and functionalization while enabling specific detection of TDP-43 in less than 1 h with a low fabrication cost of a single biosensor less than $3. [ABSTRACT FROM AUTHOR]

As the thickness of the adhesive layer between the mirror and the actuator decreases and the performance requirements of the unimorph deformable mirror (DM) increase, stricter control on the adhesive layer thickness and Young’s modulus is necessary. In this paper, a finite element model (FEM) for the unimorph DM with an adhesive layer is obtained. Based on the model, the influence of adhesive layer thickness and Young’s modulus on the deformation is studied. Also their influence on the adhesive’s maximum shear stress is analyzed. In the meantime, the design principles of the adhesive layer thickness and Young’s modulus are established with the restrictions of shear failure and the maximum displacement. As a result, different adhesive Young’s modulus has corresponding requirements for the upper and lower thicknesses (<20 μm) to obtain 85% maximum displacement. Then, DMs with four different mirror thicknesses are fabricated for verification experiments. The experiments results can be matched with the simulation results. Finally, the thickness in the spin coating process of adhesive layer is explored. The adhesive layer thickness can be controlled within 12.1 μm, and the deviation of uniformity is better than ±2%. [ABSTRACT FROM AUTHOR]

To realize the quasi-quantitative Schlieren measurement of the shock train structure across the cylindrical isolator in the supersonic flow field, based on the theory of Schlieren measurement and light transmission, we propose the design scheme of conformal windows and discuss the machining feasibility with the window's parameters. The relationship between the Schlieren imaging effect, the deflection of parallel light in the Schlieren apparatus, and the conformal optical window aberrations was researched, putting forward the optical simulation model of the conformal optical windows and the quasi-quantitative Schlieren measurement. Moreover, considering the actual wind tunnel test conditions, under the speed of Mach 2 at the isolator's inlet, the distortion brought by conformal optical windows in the Schlieren observation region was simulated by the computational fluid dynamics method. Finally, the image correction algorithm for the distorted picture caused by the conformal windows was presented, and the quasi-quantitative Schlieren measurement through the conformal optical window pair was conducted for the experimental verification. The results reveal the quasi-quantitative Schlieren measurement effect across the high-precision conformal optical window pair of the cylindrical isolator, providing guidance on maintaining the balance between the manufacturing feasibility and the observation performance of conformal windows. [ABSTRACT FROM AUTHOR]

Atmosphere plasma etching methods have been applied to the machining of optics. However, due to the high chemical stability and inertness of silicon carbide (SiC) ceramics, it seems difficult to improve the material removal rate (MRR) for conventional etching methods. We have found MRR will be significantly improved while arc forms between the inductively coupled plasma and SiC ceramic surface. This etching method is called arc-enhanced plasma machining (AEPM) technology. Arc-enhanced plasma (AEP) is represented as the secondary of a high-frequency transformer considering capacitive coupling in this paper. Radio frequency (RF) voltage in AEP is measured. The RF voltage of plasma is extremely high to form arc when plasma is close to the SiC ceramic surface. The measurement results of RF voltage at the metal-plasma interface show that the arc formation is related to the distance between source jet and workpiece ( D ). When D is small, a nonconductive layer of cooled argon forms over the workpiece surface, preventing arcing. Trenches are etched on SiC ceramic surface with different D , finding that the MRR is improved under the arcing action and the optimal D is obtained. [ABSTRACT FROM AUTHOR]

Because of finite stiffness of grinding system, grinding force will cause the tool deflection (the difference between actual cutting depth and nominal cutting depth). During helix path contour grinding, the grinding condition are variable at different grinding point which will bring forward different tool deflection and result in dimensional errors. This paper presents an error analysis model during multi-pass grinding, which can predict the accumulation process of surface profile error induced by tool deflection. It establishes the relationship between profile error and grinding parameters. The estimation method of key model parameters is described in the proposed model through series of experiments. According to the error analysis model, we can implement the varied feed rate and varied cutting depth method for compensating the profile error. The grinding experimentation and compensation grinding verifies the validity of error analysis model and effectiveness of compensation method, and the profile error reduced by 82.1% comparing with grinding process without compensation. [ABSTRACT FROM AUTHOR]

Surface characteristics have great influence on the optical properties especially the laser radiation resistivity of optics. In this paper, the surface characteristics evolutions of fused silica during ion-beam sputtering and their effects on the laser damage performance were investigated. The results show that roughness change is strongly removal depth dependent and a super-smooth surface (0.25 nm RMS) can be obtained by the ion-induced smoothing effect. The concentration of metal impurities (especially Ce element) in subsurface can be effectively decreased after the removal of polishing re-deposition layer. During ion-beam sputtering process, the plastic scratches can be removed while the brittle cracks can be broadened and passivated without increase in the depth direction. Laser damage threshold of fused silica improved by 36% after ion-beam sputtering treatment. Research results have a guiding significance for ion-beam sputtering process technology of fused silica optics. [ABSTRACT FROM AUTHOR]

Aiming to develop a prototype swing arm profilometer for several meter-class aspheres, we first present detailed error analysis including error motions of the swing rotary table and the part rotary table, and misalignment of the axes of the two rotary tables. The induced probing error in the normal direction of the reference sphere is calculated by considering the error motions in the coordinate transformation. A surface reconstruction algorithm is then proposed to separate the error motions of the part rotary table by stitching multiple traces. The error motions are optimally recognized and then removed from the trace measurement based on the least squares principle. We model the objective function by relating the normal error to the rigid body transformation of each trace. The basic idea is to minimize the inconsistency of all intersection points of different traces simultaneously. Finally the algorithm is verified through simulations. It shows that error motions of sub-milliradian scale are even tolerant with the surface reconstruction algorithm. [ABSTRACT FROM AUTHOR]

According to forming principle of line contact spherical generating by cup-shaped wheel, the sources of grinding error were analyzed, and a new method for error analysis and compensation was proposed in this paper. In a certain grinding condition, the grinding error caused by the pose errors between wheel and workpiece was simulated, the corresponding curve fitting of grinding error was carried out, and an appropriate parametric model was established. If the actual grinding error is known, the model can identify the corresponding pose error as well as compensate the grinding error. The simulation and experiment processes of compensation validate the efficient and workability of parametric model, and improve the grinding precision. [ABSTRACT FROM AUTHOR]

3D object detection using point cloud is an essential task for autonomous driving. With the development of infrastructures, roadside perception can extend the view range of the autonomous vehicles through communication technology. Computation time and power consumption are two main concerns when deploying object detection tasks, and a light-weighted detection model applied in an embedded system is a convenient solution for both roadside and vehicleside. In this study, a 3D Point cLoud Object deTection (PLOT) network is proposed to reduce heavy computing and ensure real-time object detection performance in an embedded system. First, a bird's eye view representation of the point cloud is calculated using pillar-based encoding method. Then a cross-stage partial network-based backbone and a feature pyramid network-based neck are implemented to generate the high-dimensional feature map. Finally, a multioutput head using a shared convolutional layer is attached to predict classes, bounding boxes, and the orientations of the objects at the same time. Extensive experiments using the Waymo Open Dataset and our own dataset are conducted to demonstrate the accuracy and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

It is necessary to quantitatively compare two measurement results which are typically in the form of error maps of the same surface figure for the purpose of cross test. The error maps are obtained by different methods or even different instruments. Misalignment exists between them including the tip-tilt, lateral shift, clocking and scaling. A fast registration algorithm is proposed to correct the misalignment before we can calculate the pixel-to-pixel difference of the two maps. It is formulated as simply a linear least-squares problem. Sensitivity of registration error to the misalignment is simulated with low-frequency features and mid-frequency features in the surface error maps represented by Zernike polynomials and spatially correlated functions, respectively. Finally by applying it to two cases of real datasets, the algorithm is validated to be comparable in accuracy to general non-linear optimization method based on sequential quadratic programming while the computation time is superiorly incomparable. [ABSTRACT FROM AUTHOR]

Ion beam figuring (IBF) provides a deterministic figuring method for fabricating ultra-high precision optical components such as lithographic objective lenses. But in the previous IBF process, the convergence of surface accuracy is often uncertain. Therefore, the iterative processing methods are mostly adopted. In the iterative process, the convergence ratio (the ratio of root mean square before and after figuring) of single figuring is relatively low. With the improvement of machining accuracy, the convergence ratio continues to decrease. The study analyzes the factors that limit the convergence ratio of single processing and the influence form and degree of each element on the convergence ratio. Furthermore, we present an IBF strategy with a high convergence ratio based on an optimized removal function. Based on this strategy, we complete the figuring experiment. The convergence ratio is much higher than the previous level. Compared with the surface of iterative figuring, the surface is simple and more favorable to figuring to sub-nanometer precision. The experimental results show that we can optimize the removal function to achieve rapid optical surface fabrication with nanometer precision. • A rapid manufacturing method with a high convergence ratio for nanometer precision optical elements is explored. • A more comprehensive analysis of the factors affecting the single IBF processing convergence ratio. • The method is based on the dynamic adjustment of equipments' performance to pursue the best convergence effect. • Evaluation of equipment processing capability while improving processing efficiency. [ABSTRACT FROM AUTHOR]

To improve the material removal efficiency and surface quality of single-crystal silicon after magnetorheological finishing, a novel green chemical-mechanical magnetorheological finishing (CMMRF) fluid was developed. The main components of the CMMRF fluid are nano-Fe3O4, H2O2, CH3COOH, nanodiamond, carbonyl iron powder, and deionized water. The novel CMMRF fluid can simultaneously achieve Ra 0.32 nm (0.47 mm × 0.35 mm measurement area), Ra 0.22 nm (5 μm × 5 μm measurement area), and 1.91 × 10−2 mm3/min material removal efficiency. Comprehensive studies utilizing a scanning electron microscope and a magnetic rheometer show that the CMMRF fluid has a high mechanical removal effect due to the well-dispersed nanodiamond and nano-Fe3O4 particles. The results of Fourier transform infrared spectra and Young's modulus test reveal the mechanism of the chemical reaction and the mechanical characteristics deterioration of the modified layer. Under co-enhanced chemical and mechanical effects, an ultra-smooth and highly efficient MRF technology for single-crystal silicon is realized. [ABSTRACT FROM AUTHOR]

When fabricating optical cantilever parts with single-point diamond turning (SPDT) technique, chatter phenomenon happens and degenerates the surface quality. This paper studies the chatter phenomenon and proposes a scheme to solve the problem. A kind of viscoelastic material is presented as the auxiliary supporter under the vibration location of optical cantilever parts to suppress chatter. Mirror surfaces can be generated and surface shape can be maintained after uninstalling the supporter because of the special features of viscoelastic material which acts like solid to enhance the rigidity of the cantilevers when cutting forces act on it and acts like liquid to avoid distortion of the surface shape during setting and unsetting the supporter. The effect of the viscoelastic material is discussed by virtue of finite element simulation on the basis of elasticity theory. Cutting experiments are carried out and the cutting forces as well as the surface quality with and without viscoelastic supporter are compared. The results show that chatter is suppressed effectively by using viscoelastic supporter, and surface roughness average (Ra) of around 5 nm is obtained on the whole surface with no obvious distortion on machined surface shape. [ABSTRACT FROM AUTHOR]

Abstract: Single point diamond face flycutting technique is widely applied to fabricate potassium dihydrogen phosphate (KDP) crystals because of their characteristics of softness, brittleness, deliquescence and anisotropy. This paper studies the feasibility of machining KDP crystals through spiral turning method based on the ductile cutting mechanism of brittle materials. The spiral scratch method is employed to analyze various conditions of achieving brittle–ductile transition in different cutting directions where the critical depth of cut is obtained. The cutting forces and surface formation processes within different cutting parameters are discussed and the parameters ensuring full-aperture ductile turning are acquired. White light interferometer and Atomic Force Microscope (AFM) are used to evaluate the coherence of machined surface qualities in different cutting directions. The results indicate that the critical depth of cut varies from cutting directions significantly and fluctuates from about 200nm to 1000nm under the experimental condition. Cutting forces display periodical variation with the change of cutting direction and the periodical trend blurs, even ultimately disappears, with the decrease of the cutting parameters. Root-Mean-Square (RMS) value of the fabricated surface roughness fluctuates from 1.3nm to 1.7nm on the whole surface with no distinct anisotropic distribution of the surface morphology according to the results observed by AFM. Compared with face flycutting method, spiral turning method has capability to generate complex surface profiles such as aspheric or freeform surfaces and can also be used to compensate the deformation error of KDP crystals caused by vacuum suction during fabrication. [Copyright &y& Elsevier]

Abstract: Stitching test of large optical flats is still quite challenging. In this paper, aiming to reduce the 2nd order error accumulation effect, separation of the reference surface error from the subaperture measurements is proposed in stitching of large flats. The reference error is decomposed into power and astigmatism, residual Zernike polynomial surface and high frequency component, which are estimated or calibrated, respectively. The error separation procedure is then incorporated into the subaperture stitching algorithm. Finally experiments are presented to show the effect of error reductions in stitching test of a 600mm-aperture flat, with reference surface separated and verified by the factory report of the transmission flat. [Copyright &y& Elsevier]

Optical components with complex surfaces are more and more widely applied, but it is very difficult to manufacture these components by using traditional mechanical fabricating methods. Fast tool servo system can manufacture these complex surfaces or microstructures efficiently and accurately. The relative position between the tool and workpiece surface will vary continuously in the fast tool servo machining process, owing to the height change of workpiece profile in the same circle, and this will worsen the cutting conditions and debase the machining accuracy. In this paper, the cutting characteristics are studied in the fast tool servo machining process of complex workpiece, including the varying rule of cutting angle, and its influences on the rake angle and back angle, and the choice of machining parameters. Furthermore, the conditions for identifying tool interference are given. On the basis of the above work, two kinds of typical complex workpieces are manufactured by using fast tool servo system, including radial sinusoidal workpieces and lens array. The measuring results indicate that surface accuracy can reach 0.14 μm (peak-to-valley value) and the roughness is less than 10 nm (mean value). [ABSTRACT FROM AUTHOR]

In order to investigate the influence of material anisotropy in ductile cutting of Potassium Dihydrogen Phosphate (KDP) crystals, experiments of face cutting of (001) plane of KDP crystals are carried out by using an ultra-precision lathe with a single point diamond tool. The cutting forces, surface finish, and surface roughness in all crystallographic orientations of the machined surface are measured, and a power spectrum analysis method is used to reveal the cutting force patterns. The experimental results show that the cutting forces and surface roughness vary greatly with different crystallographic orientations of KDP crystal, and that amplitude variation of cutting forces and surface finish is closely related with the cutting parameter of the maximum undeformed chip thickness. With the maximum undeformed chip thickness below 30 nm, the amplitude variation of cutting force and surface finish is minimized, and a super-smooth surface with consistent surface finish in all the crystallographic orientations can be achieved. The surface roughness is 2.698 nm (Ra) measured by Atomic Force Microscope (AFM). These findings provide criteria for achieving a large-scale KDP crystal with consistent super-smooth surface using ductile cutting technology. [ABSTRACT FROM AUTHOR]

Abstract: In an ion-beam figuring (IBF) process, the desired material removal, which is specified to the contour algorithm to calculate dwell time, decides the calculated process time and the resulted residual surface figure error. Usually, an IBF process with more removal consumes a longer process time, although the resulted residual error is smaller, whereas an IBF process with less removal needs only a shorter process time, but the resulted residual error is greater. Therefore, in order to balance the process time and the residual error, an optimum removal should be determined. In this study, the characteristic relationship between the process time and the residual error on different specified removals is investigated first. The investigation shows that for smaller removals, the residual error decreases rapidly while the process time increases slowly, and for larger removals, the process time increases rapidly without much decrease in residual error. This characteristic makes the figure-prediction curve (process times vs. rediual errors (RMS)) often in the shape of the letter “L”. Therefore, the optimum removal can be determined at the corner of the curve. Finaly, experiments are performed to verify the proposed method. [Copyright &y& Elsevier]

Galactose-α1,3-galactose (α1,3Gal) is the major xenoantigen causing hyperacute rejection in pig-to-human xenotransplantation. Disruption of the gene encoding pig (α1,3-galactosyltransferase (α1,3GT) by homologous recombination is a means to completely remove the α1,3Gal epitopes from xenografts. Here we report the disruption of one allele of the pig α1,3GT gene in both male and female porcine primary fetal fibroblasts. Targeting was confirmed in 17 colonies by Southern blot analysis, and 7 of them were used for nuclear transfer. Using cells from one colony, we produced six cloned female piglets, of which five were of normal weight and apparently healthy. Southern blot analysis confirmed that these five piglets contain one disrupted pig α1,3GT allele. [ABSTRACT FROM AUTHOR]

Currently, meter-long guideways rarely achieve an accuracy of dozens of nanometers due to processing difficulties such as the material and the edge effect. In this paper, we focus on this problem and propose a set of optimization processing methods to cope with it. In the grinding stage, a grinding tool is designed to improve the reciprocating processing and address the problem of warping; in the polishing stage, three different processes are compared, and the combination of magnetorheological finishing technology and the polyurethane disc technology process is purposed to reduce the polishing cycle and improve the surface figure accuracy. Moreover, through the combined process of magnetorheological finishing and smoothing, the edge effect and medium- and high-frequency error are essentially suppressed. The meter-long guideway is achieved with an accuracy of dozens of nanometers. Although the sizes of surface A/C and B/D are 1000 mm × 240 mm and 1000 mm × 160 mm, the surface figures are 20.33 nm, 22.78 nm, 39.23 nm and 26.58 nm RMS (Root Mean Square), respectively. The nanometer accuracy guideway is critical to an ultra-precision machine tool. Finally, the X-axis straightness of the profile measurement system formed by the guideway reaches 200 nm/600 mm. [ABSTRACT FROM AUTHOR]

• Ion beam polishing is investigated using atomic simulation. • Material removal and surface evolution during ion beam polishing are studied. • Higher ion dose leads to better machined surface quality, but increases thickness of amorphous layer. • Surface roughness depends on the Ar ion kinetic energy. The ion beam polishing techniques for silicon wafers play a key role in the fabrication of optical element. However, the dynamical ion beam polishing process at nanoscale time and space is very difficult to be recorded and observed, which most directly affects the quality of the machined surface. Here, the material removal and surface generation process during ion beam polishing are investigated using atomic simulation. In order to reveal the effects of the Ar ion dose, surface roughness, and Ar ion energy on surface integrity and subsurface damage, the surface topography, stress distribution, material removal rate, and radial distribution function are calculated and analyzed. As a result, the higher ion dose would generate the better machined surface quality, but increases the thickness of the amorphous layer. The initial surface roughness, including hill height and diameter, strongly affects the surface quality, due to the ion implantation depth to fall behind the maximum roughness value. Moreover, the average surface roughness, the material removing rate, and amorphous structure are significantly related to the Ar ion kinetic energy. This work demonstrates the potential of reasonable parameter optimization to prepare the ion beam polishing sample with high precision and few defects for optics applications. [ABSTRACT FROM AUTHOR]

Introduction: Integrated knowledge regarding pre‐exposure prophylaxis (PrEP) awareness and willingness to use PrEP can be useful for HIV prevention in high incidence groups. This review summarizes the awareness of PrEP and willingness to use PrEP among men who have sex with men (MSM). Methods: Online electronic databases were searched before 31 August 2021. A meta‐analysis was conducted to pool studies analysing PrEP awareness and willingness to use PrEP. LOESS regression and linear regression were applied to fit the trends over time for the proportion of MSM aware of PrEP and willing to use PrEP. Dose–response meta‐analysis (DRMA) was conducted by a restricted cubic spline model to explore the relationship between willingness to use PrEP and selected factors. Results and Discussion: A total of 156 articles involving 228,403 MSM were included. The pooled proportions of MSM aware of PrEP and willing to use PrEP were 50.0 (95% CI: 44.8–55.2) and 58.6% (95% CI: 54.8–62.4), respectively. PrEP awareness varied among countries with different economic status and different WHO regions, among different publication and research years, PrEP types and support policies. PrEP willingness differed among countries with different economic status and groups with different risks of HIV. The awareness of PrEP increased from 2007 to 2019 with a slope of 0.040260 (p<0.0001), while the proportion of MSM willing to use PrEP decreased from 2007 to 2014 (slope = –0.03647, p = 0.00390) but increased after 2014 (slope = 0.04187, p = 0.03895). The main facilitators of willingness to use PrEP were PrEP awareness, condomless sexual behaviours, high perceived risk of HIV infection and influence of social network. The main barriers were doubts about the efficacy and side effects of PrEP. DRMA results indicated that MSM with more sexual partners and lower level of education were more willing to use PrEP. No publication bias was observed. Conclusions: The proportions of PrEP awareness and willingness to use PrEP among MSM have increased since 2014, although the awareness was low and the willingness was moderate. Improving awareness of PrEP through increasing access to PrEP‐related health education and enhancing risk perceptions of HIV infection could have positive effects on the willingness to use PrEP among MSM. [ABSTRACT FROM AUTHOR]

The application of ultra-precision shaft parts is widely used, such as the spindle core of the air bearing spindle in ultra-precision machine tools. The precision of the spindle core is extremely high, and it is very difficult to obtain directly by traditional Computer Numerical Control (CNC) machine tools but is mostly obtained by manual grinding, whose machining efficiency is greatly limited. Based on the deterministic figuring theory, this paper focuses on the ultra-precision roundness, optimizing the filtering parameters of the measurement error data and studying the generation mechanism of the removal function morphology; the shape of the removal function is adjusted by combining the analysis of the figuring ability and positioning error. Finally, the optimized removal function is used on an experimental steel shaft, the average roundness convergence ratio is 72% higher than that of the original removal function, and the roundness reaches a 0.1 μm level. The result shows that a reasonable filtering of measured data and the removal function adjusted for the surface feature can improve the efficiency and precision of deterministic figuring on shaft parts. [ABSTRACT FROM AUTHOR]

Nanoscale laser damage precursors generated from fabrication have emerged as a new bottleneck that limits the laser damage resistance improvement of fused silica optics. In this paper, ion beam etching (IBE) technology is performed to investigate the evolutions of some nanoscale damage precursors (such as contamination and chemical structural defects) in different ion beam etched depths. Surface material structure analyses and laser damage resistance measurements are conducted. The results reveal that IBE has an evident cleaning effect on surfaces. Impurity contamination beneath the polishing redeposition layer can be mitigated through IBE. Chemical structural defects can be significantly reduced, and surface densification is weakened after IBE without damaging the precision of the fused silica surface. The photothermal absorption on the fused silica surface can be decreased by 41.2%, and the laser-induced damage threshold can be raised by 15.2% after IBE at 250 nm. This work serves as an important reference for characterizing nanoscale damage precursors and using IBE technology to increase the laser damage resistance of fused silica optics. [ABSTRACT FROM AUTHOR]

Innentitelbild: Exploring the Trans-Cleavage Activity of CRISPR-Cas12a (cpf1) for the Development of a Universal Electrochemical Biosensor (Angew. B Ein elektrochemischer Biosensor (E-CRISPR), b der auf CRISPR-Cas12a (cpf1) basiert, wird von Y. Dai, A. I. Caplan, C. C. Liu et al. in ihrem Forschungsartikel auf S. 17560 vorgestellt. Bioanalytische Chemie, Biosensoren, CRISPR Cas12a (cpf1), Elektrochemie, Trans-Spaltung. [Extracted from the article]

Inkjet printing is rapidly emerging as a means to fabricate low‐cost electronic devices; however, its widespread adoption is hindered by the complexity of the inks and the relatively high processing temperatures, limiting it to only a few metals and substrates. A new approach for inkjet printing is described, based on commercially available, particle‐free inks formulated from inorganic metal salts and their subsequent low‐temperature conversion to metallic structures by a non‐equilibrium, inert gas plasma. This single, general method is demonstrated for a library of metals including gold (Au), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt), lead (Pb), bismuth (Bi), and tin (Sn). As one figure of merit, the resistivities of the printed metals are measured to be between 2× and 10× of the respective bulk metals. Uniquely, it is found that the printed metal films exhibit a very large surface area because of the plasma‐initiated nucleation and growth process, making this technique attractive for sensing device applications. A Bi‐based trace Pb sensor, an Au‐based amyloid‐β42 sensor, and an Au‐based strain gauge are fabricated as representative chemical, biological, and mechanical sensors, and are found to exhibit enhanced sensitivity compared to analogues made with conventional methods. [ABSTRACT FROM AUTHOR]

A deterministic figuring method for cylindrical surface based on abrasive belt polishing is proposed in this study in order to improve the geometric accuracy of metal shaft parts. The principal motion of material removal is performed through the axial oscillation of the abrasive belt, and the different material removal at different positions can be obtained through servo control of the machine tool spindle by removing high error spots on the cylindrical surface and finally deterministically corrects the roundness error. An abrasive belt-based deterministic figuring device was built, and the figuring experiments were performed on the surface of steel workpieces 100 mm in diameter and 130 mm in effective length. The roundness errors of the entire workpiece after twice figuring iterations decreased nearly from the initial 3 μm to 1 μm, which preliminary verified the feasibility of this method. This deterministic figuring method is expected to break the machining accuracy limit and improve the rotation precision of the precision shaft parts such as the aerostatic spindle. [ABSTRACT FROM AUTHOR]