W1-Net: a highly scalable ptychography convolutional neural network

X-ray ptychography is a coherent diffraction imaging technique that allows for the quantitative retrieval of both the amplitude and phase information of a sample in diffraction-limited resolution. However, traditional reconstruction algorithms require a large number of iterations to obtain phase and amplitude images exactly, and the expensive computation precludes real-time imaging. To solve the inverse problem of ptychography data, PtychoNN uses deep convolutional neural networks for real-time imaging. However, its model is relatively simple, and its accuracy is limited by the size of the training dataset, resulting in lower robustness. To address this problem, a series of W-Net neural network models have been proposed which can robustly reconstruct the object phase information from the raw data. Numerical experiments demonstrate that our neural network exhibits better robustness, superior reconstruction capabilities and shorter training time with high-precision ptychography imaging

Organophosphorus Compounds. Part 43. A Molecular Mechanics Study: the Structural Effect of Cyclic Esters of Phosphorus-based Acids in Hydrolytic Reaction

Hydrolytic reactions of some cyclic esters of alkylphosphates and phosphonates have been studied using molecular mechanics calculations A great deal of attention has been devoted to the hydrolytic behaviour of cyclic esters of phosphorus acids. Interest in this reaction has been largely associated with the understanding of the mechanism of enzymatic hydrolysis'-3 and the pseudorotation process4,' of these physiologically active phosphorus Unfortunately, there are few reports concerned with quantitative or semiquantitative studies of the hydrolytic reaction of cyclic organophosphorus esters. ' The electronegativity and HMO investigations provide a good explanation of the observed product ratio of the ring opening and retention in the hydrolysis of 2-methoxy-2-0x0-1,3,2-dioxaphospholane (1) and 2-methoxy-2-0x0-1,2-oxaphospholane (2), but these methods are unable to rationalize the effects of ring size and endocyclic substituent on the hydrolytic rate constant. The substituent effect on the alkaline hydrolysis of both cyclic and acyclic phosphonyl chlorides has been investigated successfully by us12-14 using Allinger's 1977 force field, MM2 1985 program. However, the effect of the ring size and endocyclic substituents has not been considered in that treatment. In this paper, molecular mechanics calculations (MM2 1985) are used to investigate the hydrolysis reaction of the following cyclic phosphorus compounds including (l), (2), 2-ethoxy-2-oxo-1,2-oxaphospholane (3), 2-ethoxy-2-0x0-1,2-oxaphosphorinane (4), 2-ethoxy-2-oxo-1,2-oxaphosphepane (5), diethyl ethylphosphonate (6), l-methoxy-l-oxo-2,2,3-trimethylphosphetane (7), and 1-methoxy-1-oxo-2,2,3,4,4-pentamethylphosphetane (8). The calculation results indicate that the ratio of the ring opening and retention products in the hydrolysis of (1) and (2), and the effect of the ring size and the endocyclic substituents are mainly controlled by the steric energy difference (AE or AAE) between the substrate and its pentaco-ordinated transition state. Calculations Allinger's 1977 force field and MM2 1985 program" were used and all calculations were carried out on a Vax-780 computer at Shanghai Institute of Organic Chemistry, Chinese Academy of Science. Since only van der Waals parameters are used in the program, the other parameters for the tetraco-ordinated and pentaco-ordinated phosphorus compounds were calibrated in our laboratory. ' For the calculations of pentaco-ordinated phosphorus compounds the MM2 force field was modified by us.12 In order to evaluate the difference in stability of trigonal bipyramid (TBP) and square pyramid (SP), 1,3-van der Waals (VDW) interactions between the atoms directly bonded to the pentaco-ordinated phosphorus atom were added into the MM2 force field. A similar method has been used to modify the MM1 force field by Holmes.'6 In the present treatment the VDW radius for 1,3-VDW interactions is different and larger than that for 1,4-or longer VDW interactions. This not only gives a reliable energy difference value between TBP and SPY but also the correct bond angles around the pentaco-ordinated phosphorus atom bonding with different atoms. If the initial conformation is assigned as trigonal bipyramidal or square pyramidal, after minimization the structure will basically remain TBP or SP because different natural bond length and bond angle parameters for TBP and SP are assigned in the program. However, the minimization structure may deviate slightly from the standard TBP or SP owing to steric interactions. In the present case only TBP or SP were considered since they are two well studied geometries in crystal structures. Also the leaving group in the alkaline hydrolysis reaction of phosphorus esters is usually considered to be located in the axial position of a trigonal bipyramid. Some parameters for particular groups are so far not available owing to a lack of experimental data. In such cases some approximation was made, for example, the calculation parameters for the bonds P-0-and P-OH2 were replaced by these for P-OH. The geometry of each compound and transition state was optimized by using the MM2 1985 program, and the most stable conformation was selected for comparison purposes. However, the general molecular mechanics calculations are only representative of the gas-phase conditions. In order to study the reactions in solution, the solvent effect should be taken into consideration, but this effect is very difficult to evaluate in a simple way. Fortunately, in the present investigation the reactions proceed through the TBP intermediates from the same substrate and in the same solvent and the difference is onl

Cerebellar ependymal cyst: a case report

RationaleIntracranial ependymal cysts are relatively rare. The current case report focuses on a patient who was diagnosed with an ependymal cyst and underwent surgical treatment. Postoperative pathological examination confirmed the presence of this lesion in the cerebellum.Chief complaintA 32-year-old female patient presented with a chief complaint of dizziness and headache with no triggers for the past 1 year. She also reported an increase in the frequency and intensity of symptoms in the past 2 weeks.DiagnosisCranial magnetic resonance imaging (MRI) showed a rounded long T1 and T2 abnormal signal foci in the left posterior part of the brainstem under the cerebellar pallidum. The lesion had a clear boundary, was approximately 4.0 × 3.1 × 3.2 cm in size, and did not exhibit any definitive enhancement.InterventionsTotal resection of the lesion was carried out after completion of the preoperative examination.Treatment outcomes. The patient was discharged from the hospital on postoperative day 11 once their symptoms had disappeared. The sensory and motor functions of the limbs remained unaffected by treatment.ExperiencesCerebellum ependymal cysts are rare, and most patients only experience discomfort due to cerebral edema. These lesions are also often difficult to differentiate from other intracranial cysts using imaging alone. The aim of this study was to report a rare case of ependymal cyst so that it may serve as a reference for diagnosis and treatment in the future

Two-Stage Adaptive Network for Semi-Supervised Cross-Domain Crater Detection under Varying Scenario Distributions

Crater detection can provide valuable information for humans to explore the topography and understand the history of extraterrestrial planets. Due to the significantly varying scenario distributions, existing detection models trained on known labelled crater datasets are hardly effective when applied to new unlabelled planets. To address this issue, we propose a two-stage adaptive network (TAN) for semi-supervised cross-domain crater detection. Our network is built on the YOLOv5 detector, where a series of strategies are employed to enhance its cross-domain generalisation ability. In the first stage, we propose an attention-based scale-adaptive fusion (ASAF) strategy to handle objects with significant scale variances. Furthermore, we propose a smoothing hard example mining (SHEM) loss function to address the issue of overfitting on hard examples. In the second stage, we propose a sort-based pseudo-labelling fine-tuning (SPF) strategy for semi-supervised learning to mitigate the distributional differences between source and target domains. For both stages, we employ weak or strong image augmentation to suit different cross-domain tasks. Experimental results on benchmark datasets demonstrate that the proposed network can enhance domain adaptation ability for crater detection under varying scenario distributions

Structural evolution and thermal runaway of refractory W and Mo nanotips in the vacuum under high electric field from PIC-ED-MD simulations

We performed multiscale-multiphysics simulations for W, Mo and Cu nanotips under high electric field to investigate their structural evolution and thermal runaway process. The critical electric field values for the electric prebreakdown condition are predicted to be 311 MV m(-1), 570 MV m(-1) and 675 MV m(-1) for Cu, Mo and W nanotips respectively (R (0) = 1 nm, H (0) = 100 nm). The boiling point of the metal is found to be a good predictor of the critical electric field strength for the initiation of thermal runaway. For metal nanotips made of refractory metals such as W and Mo, the structural thermal runaway process is determined by the rapid growth of small protrusions and their subsequent sharpening and thinning under the high electric stress on the apex region. On the other hand, the more intense atomic evaporation of Cu metal nanotips is caused by the ejection of large droplets generated by recrystallization and necking of the molten region at the apex of the nanotip. The differences in the observed structural evolutions of nanotips between refractory metals and the Cu during the thermal runaway event clearly show the strong influence of melting and boiling points on the electric prebreakdown process in nanoscale.Peer reviewe

An integrated ecosystem monitoring technology for coal mining subsidence areas and its application in the Shendong mining area

BackgroundThe ecosystem monitoring of arid and semi-arid coal mining subsidence areas acts as a significant prerequisite for regional ecosystem conservation and management, holding critical significance for accelerating green mine construction. MethodsBased on the Chinese government's regulatory requirements for mine ecosystems, this study analyzed the difficulties in ecosystem monitoring in the coal mining subsidence area of the Shendong mining area (also referred to as the Shendong coal mining subsidence area). By detailing the integrated coal-rock-water-soil-air-vegetation-carbon monitoring technology system, this study determined the factors, principal methods, and technology roadmap for the integrated ecosystem monitoring in the Shendong coal mining subsidence area. Accordingly, this study delved into the spatiotemporal synergistic relationships of the space-air-tower-ground-laboratory multi-platform observations and then developed the Shendong ecosystem monitoring platform, which was applied to the integrated ecosystem monitoring in the Shendong coal mining subsidence area. Results and Conclusions The results indicate that the integrated ecosystem monitoring technology system, combined with the space-air-tower-ground-laboratory multi-platform observations, comprehensively accounts for the requirements of various regulatory authorities and the advantages of different observation platforms, achieves the synergistic analysis of multiple ecological factors and the coordination of various regulatory authorities, and fulfills the requirements of multiple regulatory authorities for indicator coverage and monitoring efficiency. The Shendong ecosystem monitoring platform, integrating models including the efficient organization and management model of multi-source data and the intelligent decision-making model, enables the management and spatiotemporal collaborative processing of multi-source heterogeneous big data, as well as the intelligent decision-making for ecological restoration based on the big data from multi-source monitoring, facilitating the ecological restoration engineering and routine plant care in the Shendong coal mining subsidence area. The integrated ecosystem monitoring technology has been applied in the green mine construction of the Shendong mining area, achieving encouraging outcomes in the decision-making for the optimization of plant types and planting density, the assessment of vegetation growth and soil moisture content, and the intelligent monitoring and acceptance check of plant quantities and survival rates in the restoration engineering. This study provides a typical case for ecosystem monitoring and management in arid and semi-arid coal mining subsidence areas