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Utilization of nanohydroxyapatite-kaolin composites as a slow-release materials of urea

Materials Chemistry and Physics 2025年 342卷

作者： Noviyanti, Atiek Rostika Fajrina, Yulia Eddy, Diana Rakhmawaty Irkham Hartati, Yeni Wahyuni Rupaedah, Bedah Suryana Permana, Muhamad Diki Karnjanakom, Surachai Guan, Guoqing Kurnia, Irwan Department of Chemistry Faculty of Mathematics and Natural Sciences Universitas Padjadjaran Jl. Raya Bandung-Sumedang Km 21 Jatinangor West Java Sumedang45363 Indonesia Research Center for Applied Microbiology National Research and Innovation Agency Jl. Raya Jakarta-Bogor Km. 46 Cibinong West Java Bogor16911 Indonesia Department of Biology Faculty of Mathematics and Natural Sciences Universitas Padjadjaran Jl. Raya Bandung-Sumedang Km 21 Jatinangor West Java Sumedang45363 Indonesia Special Educational Program for Green Energy Conversion Science and Technology Integrated Graduate School of Medicine Engineering and Agricultural Sciences University of Yamanashi Kofu400-8511 Japan Center for Crystal Science and Technology University of Yamanashi Kofu400-8511 Japan Department of Chemistry Faculty of Science Rangsit University 52/347 Phahonyothin Road Pathum Thani 12000 Thailand Institute of Regional Innovation Hirosaki University 3-Bunkyocho Hirosaki036-8561 Japan

Urea is widely used as a nitrogen-source fertilizer in agriculture, but its leaching due to rainwater leads to eutrophication and environmental pollution. To address this, urea was incorporated into nanohydroxyapatite (nHA)–kaolin (KA) composites (HKs) that were synthesized via a two-step hydrothermal method as a slow-release materials (SRMs). Among the composites, HK1 (nHA:KA 75:25) is the most promising slow-release material with a urea release rate of 57.0 μgurea min−1 (20.3 % for 240 min), which is 4.6 times slower than urea release rate of nHA-urea for 262.9 μgurea min−1 (93.5 %, 240 min). This enhanced slow-release behavior is attributed to synergistic interactions between nHA and KA, as reflected on their zeta potentials. These findings suggest that HKs are promising slow-release materials for improving fertilizer efficiency and mitigating environmental impact in agricultural applications. © 2025 Elsevier B.V.

关键词： Urea fertilizers

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Exact Periodic Solitary Solutions to the Shallow Water Wave Equation

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Chinese Physics Letters 2009年第5期26卷 151-153页

作者：李栋龙赵俊霄 Department of Information and Computation Science Guangxi University of Technology Liuzhou 545006 Institute of Applied Physics and Computational Mathematics Beijing 100088 School of Mathematical Sciences Graduate University of Chinese Academy of Sciences Beijing 100049

Exact solutions to the shallow wave equation are studied based on the idea of the extended homoclinic test and bilinear method. Some explicit solutions, such as the one soliton solution, the doubly-periodic wave solution and the periodic solitary wave solutions, are obtained. In addition, the properties of the solutions are investigated.

关键词： gamma-ray bursts gamma-rays relativity

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An Iterative Thresholding Method for the Minimum Compliance Problem

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Communications in computational Physics 2023年第4期33卷 1189-1216页

作者： Luyu Cen Wei Hu Dong Wang Xiaoping Wang Department of Mathematics Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina The Program in Applied and Computational Mathematics Princeton UniversityPrincetonNew JerseyUSA School of Science and Engineering The Chinese University of Hong KongShenzhenGuangdong 518172China Shenzhen International Center for Industrial and Applied Mathematics Shenzhen Research Institute of Big DataGuangdong 518172China

In this paper,we propose a simple energy decaying iterative thresholding algorithm to solve the two-phase minimum compliance *** material domain is implicitly represented by its characteristic function,and the problem is formulated into a minimization problem by the principle of minimum complementary *** prove that the energy is decreasing in each *** effective continuation schemes are proposed to avoid trapping into the local *** results on 2D isotropic linear material demonstrate the effectiveness of the proposed methods.

关键词： Minimum compliance convolution thresholding linear elasticity

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DeePKS + ABACUS as a Bridge between Expensive Quantum Mechanical Models and Machine Learning Potentials

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Journal of Physical Chemistry A 2022年第49期126卷 9154-9164页

作者： Li, Wenfei Ou, Qi Chen, Yixiao Cao, Yu Liu, Renxi Zhang, Chunyi Zheng, Daye Cai, Chun Wu, Xifan Wang, Han Chen, Mohan Zhang, Linfeng AI for Science Institute Beijing100080 China Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States HEDPS CAPT College of Engineering School of Physics Peking University Beijing100871 China Department of Physics Temple University PhiladelphiaPA19122 United States Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Huayuan Road 6 Beijing100088 China DP Technology Beijing100080 China

Recently, the development of machine learning (ML) potentials has made it possible to perform large-scale and long-time molecular simulations with the accuracy of quantum mechanical (QM) models. However, for different levels of QM methods, such as density functional theory (DFT) at the meta-GGA level and/or with exact exchange, quantum Monte Carlo, etc., generating a sufficient amount of data for training an ML potential has remained computationally challenging due to their high cost. In this work, we demonstrate that this issue can be largely alleviated with Deep Kohn-Sham (DeePKS), an ML-based DFT model. DeePKS employs a computationally efficient neural network-based functional model to construct a correction term added upon a cheap DFT model. Upon training, DeePKS offers closely matched energies and forces compared with high-level QM method, but the number of training data required is orders of magnitude less than that required for training a reliable ML potential. As such, DeePKS can serve as a bridge between expensive QM models and ML potentials: one can generate a decent amount of high-accuracy QM data to train a DeePKS model and then use the DeePKS model to label a much larger amount of configurations to train an ML potential. This scheme for periodic systems is implemented in a DFT package ABACUS, which is open source and ready for use in various applications. © 2022 The Journal of Physical Chemistry A. All right reserved.

关键词： Density functional theory

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SURREAL-GAN:SEMI-SUPERVISED REPRESENTATION LEARNING VIA GAN FOR UNCOVERING HETEROGENEOUS DISEASE-RELATED IMAGING PATTERNS 10

SURREAL-GAN:SEMI-SUPERVISED REPRESENTATION LEARNING VIA GAN ...

引用

10th International Conference on Learning Representations, ICLR 2022

作者： Yang, Zhijian Wen, Junhao Davatzikos, Christos Center for Biomedical Image Computing and Analytics University of Pennsylvania United States Graduate Group in Applied Mathematics and Computational Science University of Pennsylvania United States

A plethora of machine learning methods have been applied to imaging data, enabling the construction of clinically relevant imaging signatures of neurological and neuropsychiatric diseases. Oftentimes, such methods do not explicitly model the heterogeneity of disease effects, or approach it via nonlinear models that are not interpretable. Moreover, unsupervised methods may parse heterogeneity that is driven by nuisance confounding factors that affect global brain structure or function, rather than heterogeneity relevant to a pathology of interest. On the other hand, semi-supervised clustering methods seek to derive a pathology-related dichotomous subtypes, ignoring the truth that disease heterogeneity spatially and temporally extends along a continuum. To address the aforementioned limitations, herein, we propose a novel method, termed Surreal-GAN (Semi-SUpeRvised ReprEsentAtion Learning via GAN). Using cross-sectional imaging data, Surreal-GAN dissects underlying disease-related heterogeneity under the principle of semi-supervised clustering [cluster mappings from the normal control (CN) to patient (PT) domain], proposes a continuously dimensional representation, and infers the disease severity of patients at individual level along each dimension. The model first learns a transformation function from the CN domain to the PT domain with latent variables controlling transformation directions. An inverse mapping function together with regularization on function continuity, pattern orthogonality and monotonicity was also imposed to make sure that the transformation function captures necessarily meaningful imaging patterns with clinical significance. We first validated the model through semi-synthetic experiments, and then demonstrated its potential in capturing biologically plausible imaging patterns in Alzheimer's disease (AD). © 2022 ICLR 2022 - 10th International Conference on Learning Representationss. All rights reserved.

关键词： Pathology

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Simulation of Hydrogen Emission Spectrum in Debye Plasmas

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Chinese Physics Letters 2011年第5期28卷 84-87页

作者： DING Qi-Yong ZHANG Song-Bin WANG Jian-Guo The Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009Beijing 100088 Graduate School of China Academy of Engineering Physics P.O.Box 2101Beijing 100088 Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics University of Science and Technology of ChinaHefei 230026

We investigate the screening effects on the spectrum of spontaneous radiation and radiative recombination to the 1s,2s and 2p states of hydrogen with total atom density N=1.7×10^(19)cm^(-3)and electron temperatures 1eV,2eV and 5eV under the local thermodynamic equilibrium(LTE)*** needed atomic energy levels,the radiative transition probabilities and radiative recombination cross sections are calculated by solving the Schr(o)dinger equation numerically incorporating the Debye-Hückel model in *** plasma emission spectrum is simulated for the first time by using the screened atomic *** red shift and the cutoff of Rydberg spectra are observed and it is also found that the 2 eV electron temperature case has the strongest screening effects and the emission spectra to the 2s and 2p states are more likely affected by screening effects than that of the ls state.

关键词： Debye radiative spectrum

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Deep learning with Gaussian differential privacy

arXiv

引用

arXiv 2019年

作者： Bu, Zhiqi Dong, Jinshuo Long, Qi Su, Weijie J. Graduate Group in Applied Mathematics and Computational Science Graduate Group in Applied Mathematics and Computational Science Department of Biostatistics Epidemiology and Informatics Department of Statistics

Deep learning models are often trained on datasets that contain sensitive information such as individuals' shopping transactions, personal contacts, and medical records. An increasingly important line of work therefore has sought to train neural networks subject to privacy constraints that are specified by differential privacy or its divergence-based relaxations. These privacy definitions, however, have weaknesses in handling certain important primitives (composition and subsampling), thereby giving loose or complicated privacy analyses of training neural networks. In this paper, we consider a recently proposed privacy definition termed f-differential privacy [17] for a refined privacy analysis of training neural networks. Leveraging the appealing properties of f-differential privacy in handling composition and subsampling, this paper derives analytically tractable expressions for the privacy guarantees of both stochastic gradient descent and Adam used in training deep neural networks, without the need of developing sophisticated techniques as [3] did. Our results demonstrate that the f-differential privacy framework allows for a new privacy analysis that improves on the prior analysis [3], which in turn suggests tuning certain parameters of neural networks for a better prediction accuracy without violating the privacy budget. These theoretically derived improvements are confirmed by our experiments in a range of tasks in image classification, text classification, and recommender systems. Copyright © 2019, The Authors. All rights reserved.

关键词： Text processing

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Scattering for 3D Cubic Focusing NLS on the Domain Outside a Convex Obstacle Revisited

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Acta Mathematica Sinica,English Series 2022年第6期38卷 1054-1068页

作者： Cheng Bin XU Teng Fei ZHAO Ji Qiang ZHENG The Graduate School of China Academy of Engineering Physics Beijing 100088P.R.China School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083P.R.China Institute of Applied Physics and Computational Mathematics P.O.Box 8009Beijing 100088P.R.China

In this article,we consider the focusing cubic nonlinear Schr?dinger equation(NLS)in the exterior domain outside of a convex obstacle in R3with Dirichlet boundary *** revisit the scattering result below ground state in Killip-Visan-Zhang[The focusing cubic NLS on exterior domains in three ***,1,146-180(2016)]by utilizing the method of Dodson and Murphy[A new proof of scattering below the ground state for the 3d radial focusing cubic ***.,145,4859-4867(2017)]and the dispersive estimate in Ivanovici and Lebeau[Dispersion for the wave and the Schr?dinger equations outside strictly convex obstacles and ***.,355,774-779(2017)],which avoids using the concentration *** conquer the difficulty of the boundary in the focusing case by establishing a local smoothing effect of the *** on this effect and the interaction Morawetz estimates,we prove that the solution decays at a large time interval,which meets the scattering criterion.

关键词： Schrodinger equation exterior domain global well-posedness scattering criterion

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Large amplitude electromagnetic solitons in intense laser plasma interaction

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Chinese Physics B 2006年第9期15卷 2046-2052页

作者：李百文 Ishiguro S Skoric M M Institute of Applied Physics and Computational Mathematics Beijing 100088 China The Graduate University/or Advanced Studies and National Institute/or Fusion Science Toki 509-5292 Japan

This paper shows that the standing, backward- and forward-accelerated large amplitude relativistic electromagnetic solitons induced by intense laser pulse in long underdense collisionless homogeneous plasmas can be observed by particle simulations. In addition to the inhomogeneity of the plasma density, the acceleration of the solitons also depends upon not only the laser amplitude but also the plasma length. The electromagnetic frequency of the solitons is between about half and one of the unperturbed electron plasma frequency. The electrostatic field inside the soliton has a one-cycle structure in space, while the transverse electric and magnetic fields have half-cycle and one-cycle structure respectively. Analytical estimates for the existence of the solitons and their electromagnetic frequencies qualitatively coincide with our simulation results.

关键词： particle-in-cell (PIC) Raman cascade photon-condensation relativistic EM soliton

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Multifunctional resonant wavefront-shaping meta-optics based on multilayer and multi-perturbation nonlocal metasurfaces

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Light(science & Applications) 2022年第9期11卷 2194-2206页

作者： STEPHANIE CMALEK ADAM COVERVIG ANDREA ALÙ NANFANG YU Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY 10027USA Photonics Initiative Advanced Science Research CenterCity University of New YorkNew YorkNY 10031USA Physics Program Graduate CenterCity University of New YorkNew YorkNY 10016USA

Photonic devices rarely provide both elaborate spatial control and sharp spectral control over an incoming *** optical metasurfaces,for example,the localized modes of individual meta-units govern the wavefront shape over a broad bandwidth,while nonlocal lattice modes extended over many unit cells support high quality-factor ***,we experimentally demonstrate nonlocal dielectric metasurfaces in the near-infrared that offer both spatial and spectral control of light,realizing metalenses focusing light exclusively over a narrowband resonance while leaving off-resonant frequencies *** devices attain this functionality by supporting a quasi-bound state in the continuum encoded with a spatially varying geometric *** leverage this capability to experimentally realize a versatile platform for multispectral wavefront shaping where a stack of metasurfaces,each supporting multiple independently controlled quasi-bound states in the continuum,molds the optical wavefront distinctively at multiple wavelengths and yet stay transparent over the rest of the *** a platform is scalable to the visible for applications in augmented reality and transparent displays.

关键词： spectrum resonant supporting

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