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1.
RSC Adv ; 14(16): 11027-11036, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38586443

RESUMO

Polylactic acid (PLA) is a high-modulus, high-strength bio-based thermoplastic polyester with good biodegradability, which is currently a promising environmentally friendly material. However, its inherent brittleness has hindered its widespread use. In this study, we reported a simple and non-toxic strategy for toughening PLA, using biodegradable materials such as polyethylene glycol (PEG) and citric acid (CA) as precursors. Through reactive melt blending with PLA, PEG and CA form PEGCA copolyesters in situ during blending. At the same time, CA can react with PLA and PEG, forming a copolyester structure at the interface of the two phases, improving the interfacial compatibility between PEG and PEGCA with PLA. Fourier transform infrared spectroscopy confirms this. Experimental results show that when the content of PEG/CA reaches 15% (PLA/PEG/CA-15%) in the blends, the impact strength of the blend was 4.47 kJ m-2, and the maximum elongation at break was as high as 360.1%, which were about 2 and 44 times higher than those of pure PLA, respectively. Moreover, the tensile strength was still maintained at the level of 70%. This work can expand the application of PLA in food packaging and medical supplies.

2.
J Environ Manage ; 356: 120635, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38508001

RESUMO

The transport sector proves a major energy consumer in China, but improving energy-saving performance in China's provincial transport sector from the lifecycle perspective remains unresolved. Thus, this study employs the environmentally extended multi-region input-output (MRIO) method, structural path analysis, and the newest MRIO table of China from 2017, to investigate how to improve the energy-saving performance from final demand structure, supply chain, and pathway perspectives. The relevant results are threefold. (1) Regarding the final demand structure level, the embodied energy consumption of China's transport sector is predominantly driven by investment from the production side, while that of the consumption side is primarily caused by exports. (2) At the supply chain level, production-side embodied energy consumption primarily occurs along a three-echelon supply chain, while that from the consumption side mostly occurs via a two-echelon supply chain. (3) At the pathway level, the production-side energy-saving performance of China's provincial transport sector is dominated by two pathways along the construction sector, including transport sector → construction sector → final demands, and transport sector → intermediate inputs → construction sector → final demands, while that of the consumption side is chiefly determined by three pathways along internal transportation chains.


Assuntos
Desenvolvimento Econômico , Investimentos em Saúde , China , Meios de Transporte , Dióxido de Carbono/análise
3.
Int J Biol Macromol ; 258(Pt 1): 128520, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38040150

RESUMO

In this study, we developed an enhanced heterogeneous interface intelligent conductive hydrogel NH3 sensor for individualized treatment of infected wounds. The sensor achieved monitoring, self-diagnosis, and adaptive gear adjustment functions. The PPY@PDA/PANI(3/6) sensor had a minimum NH3 detection concentration of 50 ppb and a response value of 2.94 %. It also had a theoretical detection limit of 49 ppt for infected wound gas. The sensor exhibited a fast response time of 23.2 s and a recovery time of 42.9 s. Tobramycin (TOB) was encapsulated in a self-healing QCS/OD hydrogel formed by quaternized chitosan (QCS) and oxidized dextran (OD), followed by the addition of polydopamine-coated polypyrrole nanowires (PPY@PDA) and polyaniline (PANI) to prepare electrically conductive drug-loaded PPY@PDA/PANI hydrogels. The drug-loaded PPY@PDA/PANI hydrogel was combined with a PANI/PVDF membrane to form an enhanced heterogeneous interfacial PPY@PDA/PANI/PVDF-based sensor, which could adaptively learn the individual wound ammonia response and adjust the speed of drug release from the PPY@PDA/PANI hydrogel with electrical stimulation. Drug release and animal studies demonstrated the efficacy of the PPY@PDA/PANI hydrogel in inhibiting infection and accelerating wound healing. In conclusion, the gas-sensitive conductive hydrogel sensing system is expected to enable intelligent drug delivery and provide personalized treatment for complex wound management.


Assuntos
Quitosana , Polímeros de Fluorcarboneto , Polímeros , Polivinil , Animais , Hidrogéis/farmacologia , Pirróis
4.
J Glob Antimicrob Resist ; 36: 36-40, 2023 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-38072241

RESUMO

OBJECTIVES: Aquatic ecosystems serve as a dissemination pathway and a reservoir of both antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study aimed to determine the prevalence of colistin-resistant mcr-like genes in Enterobacteriales in aquatic products, which may be contribute to the transfer of ARGs in water environments. METHODS: The mcr-1-positive Escherichia coli were recovered from 123 freshwater fish and 34 cultured crocodile cecum samples from 10 farmers' markets in Guangdong, China. Minimum inhibitory concentration (MIC) was determined using the agar dilution method. Genotyping was performed using pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Conjugation assay was carried out to investigate the transferability of mcr-1. Genomic information was obtained by whole genome sequencing (WGS) and bioinformatic analysis. RESULTS: Forty-four mcr-1 positive isolates showed co-resistance to tetracycline, trimethoprim/sulfamethoxazole, and gentamicin, while they were all sensitive to tigecycline, meropenem, and amikacin. They were typed into sixteen PFGE clusters. ST10 and ST117 were the most popular sequence types, followed by ST1114. S1-PFGE verified the presence of the mcr-1 gene on plasmids in sizes of ∼60 kb (n = 1) and ∼240 kb (n = 3). Whole genome sequencing-based analysis identified mcr-1 integrated in IncHI2 plasmid (n = 3), IncI2 plasmid (n = 2), and bacterial chromosome in two copies (n = 1). In addition to mcr-1, they carried several other antibiotic resistance genes, such as blaCTX-M-14, fosA3, and aac(6')-Ib-cr. CONCLUSION: These data suggest that aquatic products are an important antibiotic resistance reservoir and highlight possible risks regarding food safety.

5.
Biomedicines ; 11(6)2023 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-37371649

RESUMO

Plant-derived exosomes (PLDEs) are small extracellular vesicles that encapsulate proteins, nucleic acids and lipids, and they are usually involved in intercellular communication and molecular transport in plants. PLDEs are widely used in the therapy of diseases due to their abundance and easy availability. The diverse roles of PLDEs, which include transportation of drugs, acting as biomarkers for diagnosis of diseases and their roles in different therapies, suggest that there is a need to fully understand all the mechanisms involved in order to provide the optimum conditions for their therapeutic use. This review summarizes the biogenesis, components and functions of PLDEs and focuses on their use as therapeutic agents in the treatment of inflammatory diseases. It also explores new ideas for novel approaches in which PLDEs could potentially help patients with inflammatory diseases in the future.

6.
Nanoscale ; 15(23): 10050-10056, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-37248968

RESUMO

Memristive synapses compatible with optogenetic techniques allow for the fast and low-power manipulation of memory activities using light in artificial neural systems. However, most of the optoelectronic memristors operate in the hybrid optic-electric mode; the reversible regulation of memristive states solely using light for optogenetic emulation is difficult. In this work, an all-optical controlled optoelectronic memristor (Au/Cs2AgBiBr6/Au) is developed for mimicking optogenetics-tuned memory formation and erasing behaviors in biological synapses. We show that the memristor exhibits positive and negative persistent photoconductivity effects under different light wavelengths, attributed to light-regulated carrier de-trapping/trapping at the Au/Cs2AgBiBr6 interface. This device can emulate both excitatory and inhibitory synaptic plasticity and associated learning and memory effects under light illumination. We constructed a prototype optoelectronic synaptic array and implemented the all-optically controlled memory implantation, erasing, and modification, demonstrating the light-reconfigured cognition capabilities. Our findings will inspire the development of all-optically controlled artificial neural systems with good reconfigurability for efficient neuromorphic computing and machine vision.


Assuntos
Cognição , Optogenética , Eletricidade , Excipientes , Olho
7.
Financ Innov ; 9(1): 75, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37063169

RESUMO

Forecasting returns for the Artificial Intelligence and Robotics Index is of great significance for financial market stability, and the development of the artificial intelligence industry. To provide investors with a more reliable reference in terms of artificial intelligence index investment, this paper selects the NASDAQ CTA Artificial Intelligence and Robotics (AIRO) Index as the research target, and proposes innovative hybrid methods to forecast returns by considering its multiple structural characteristics. Specifically, this paper uses the ensemble empirical mode decomposition (EEMD) method and the modified iterative cumulative sum of squares (ICSS) algorithm to decompose the index returns and identify the structural breakpoints. Furthermore, it combines the least-square support vector machine approach with the particle swarm optimization method (PSO-LSSVM) and the generalized autoregressive conditional heteroskedasticity (GARCH) type models to construct innovative hybrid forecasting methods. On the one hand, the empirical results indicate that the AIRO index returns have complex structural characteristics, and present time-varying and nonlinear characteristics with high complexity and mutability; on the other hand, the newly proposed hybrid forecasting method (i.e., the EEMD-PSO-LSSVM-ICSS-GARCH models) which considers these complex structural characteristics, can yield the optimal forecasting performance for the AIRO index returns.

8.
Adv Sci (Weinh) ; 10(15): e2300471, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36950731

RESUMO

The recent emergence of various smart wearable electronics has furnished the rapid development of human-computer interaction, medical health monitoring technologies, etc. Unfortunately, processing redundant motion and physiological data acquired by multiple wearable sensors using conventional off-site digital computers typically result in serious latency and energy consumption problems. In this work, a multi-gate electrolyte-gated transistor (EGT)-based reservoir device for efficient multi-channel near-sensor computing is reported. The EGT, exhibiting rich short-term dynamics under voltage modulation, can implement nonlinear parallel integration of the time-series signals thus extracting the temporal features such as the synchronization state and collective frequency in the inputs. The flexible EGT integrated with pressure sensors can perform on-site gait information analysis, enabling the identification of motion behaviors and Parkinson's disease. This near-sensor reservoir computing system offers a new route for rapid analysis of the motion and physiological signals with significantly improved efficiency and will lead to robust smart flexible wearable electronics.


Assuntos
Dispositivos Eletrônicos Vestíveis , Humanos , Eletrônica , Marcha , Análise da Marcha , Eletrólitos
9.
Opt Express ; 31(5): 8375-8383, 2023 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-36859952

RESUMO

The integrated optical isolator is an essential building block in photonic integrated chips. However, the performance of on-chip isolators based on the magneto-optic (MO) effect has been limited due to the magnetization requirement of permanent magnets or metal microstrips on MO materials. Here, an MZI optical isolator built on a silicon-on-insulator (SOI) without any external magnetic field is proposed. A multi-loop graphene microstrip operating as an integrated electromagnet above the waveguide, instead of the traditional metal microstrip, generates the saturated magnetic fields required for the nonreciprocal effect. Subsequently, the optical transmission can be tuned by varying the intensity of currents applied on the graphene microstrip. Compared with gold microstrip, the power consumption is reduced by 70.8%, and temperature fluctuation is reduced by 69.5% while preserving the isolation ratio of 29.44 dB and the insertion loss of 2.99 dB at1550 nm.

10.
Comput Biol Med ; 155: 106623, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36809696

RESUMO

In this article, we propose a lightweight and competitively accurate heart rhythm abnormality classification model based on classical convolutional neural networks in deep neural networks and hardware acceleration techniques to address the shortcomings of existing wearable devices for ECG detection. The proposed approach to build a high-performance ECG rhythm abnormality monitoring coprocessor achieves a high degree of data reuse in time and space, which reduces the number of data flows, provides a more efficient hardware implementation and reduces hardware resource consumption than most existing models. The designed hardware circuit relies on 16-bit floating-point numbers for data inference at the convolutional, pooling, and fully connected layers, and implements acceleration of the computational subsystem through a 21-group floating-point multiplicative-additive computational array and an adder tree. The front- and back-end design of the chip was completed on the TSMC 65 nm process. The device has an area of 0.191 mm2, a core voltage of 1 V, an operating frequency of 20 MHz, a power consumption of 1.1419 mW, and requires 5.12 kByte of storage space. The architecture was evaluated using the MIT-BIH arrhythmia database dataset, which showed a classification accuracy of 97.69% and a classification time of 0.3 ms for a single heartbeat. The hardware architecture offers high accuracy with a simple structure, low resource footprint, and the ability to operate on edge devices with relatively low hardware configurations.


Assuntos
Cardiopatias Congênitas , Dispositivos Eletrônicos Vestíveis , Humanos , Algoritmos , Frequência Cardíaca , Processamento de Sinais Assistido por Computador , Redes Neurais de Computação , Eletrocardiografia/métodos
11.
Polymers (Basel) ; 15(3)2023 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-36771863

RESUMO

Utilizing the copolymerization modification of dimethyl diallyl ammonium chloride (DMDAAC), the high positive charge density of the copolymer could be maintained, thereby facilitating the deficiency of its monomer in the application. In this paper, poly (DMDAAC-co-DAMBAC) (9:1) was synthesized with an aqueous polymerization method using DMDAAC and methyl benzyl diallyl ammonium chloride (DAMBAC) as monomers and 2,2'-azobis [2-methylpropionamidine] dihydrochloride (V50) as an initiator. Targeted to the product's weight-average relative molecular mass (Mw), the response surface methodology (RSM) was used to optimize the preparation process. The optimal process conditions were obtained as follows: w (M) = 80.0%, m (V50):m (M) = 0.00700%, m (Na4EDTA):m (M) = 0.00350%, T1 = 50.0 °C, T2 = 60.0 °C, and T3 = 72.5 °C. The intrinsic viscosity ([η]) of the product was 1.780 dL/g, and the corresponding double bond conversion (Conv.) was 90.25 %. Poly (DMDAAC-co-DAMBAC) (9:1) revealed a highest Mw of 5.637 × 105, together with the polydispersity index d (Mw/Mn) as 1.464. For the demulsification performance of simulated crude oil O/W emulsions, the demulsification rate of poly (DMDAAC-co-DAMBAC) (9:1) could reach 97.73%. Our study has illustrated that the copolymerization of DMDAAC and a small amount of DAMBAC with poor reactivity could significantly improve the relative molecular weight of the polymer, enhance its lipophilicity, and thus the application scope of the polymer.

12.
Micromachines (Basel) ; 13(10)2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-36296053

RESUMO

Reservoir Computing (RC) is a network architecture inspired by biological neural systems that maps time-dimensional input features to a high-dimensional space for computation. The key to hardware implementation of the RC system is whether sufficient reservoir states can be generated. In this paper, a laboratory-prepared zinc oxide (ZnO) memristor is reported and modeled. The device is found to have nonlinear dynamic responses and characteristics of simulating neurosynaptic long-term potentiation (LTP) and long-term depression (LTD). Based on this, a novel two-level RC structure based on the ZnO memristor is proposed. Novel synaptic encoding is used to maintain stress activity based on the characteristics of after-discharge and proneness to fatigue during synaptic transmission. This greatly alleviates the limitations of the self-attenuating characteristic reservoir of the duration and interval of the input signal. This makes the reservoir, in combination with a fully connected neural network, an ideal system for time series classification. The experimental results show that the recognition rate for the complete MNIST dataset is 95.08% when 35 neurons are present as hidden layers while achieving low training consumption.

13.
J Chem Phys ; 157(15): 154902, 2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36272789

RESUMO

Lipopolysaccharides (LPSs) are negatively charged molecules covering the surface of Gram-negative bacteria (GNB). Adding divalent cations (DCs) is important to stabilize the LPS bilayer. Thus, DCs are always only considered as membrane stabilizing ions. Here, on the basis of a coarse-grained (CG) Martini force field, we conduct molecular dynamic (MD) simulations to study the divalent cation mediated LPS interaction and the stability of the LPS membrane in a wide range of DC concentrations. By measuring the LPS binding free energy and the LPS-LPS aggregate from the association course between two LPS molecules, we find that the initial addition of DCs may significantly facilitate the aggregation of LPSs into a compact structure, while sequentially adding more DCs only unpacks the LPS aggregate and drives the dissolution of LPSs. With an increasing concentration of DCs, we find a gradual replacement of DCs to monovalent cations as condensed counterions on the LPS, which follows a sign change from negative to positive in terms of the LPS effective charge and a switch of LPSs in solution from undergoing precipitation to resolubilization on adding DCs. This interaction change in the level of two LPSs accounts for the structure variation of the LPS assembly on a larger scale, where the LPS packing rigidity in the assembly bilayer is found with a similar nonmonotonic dependence with the DC concentration. Thus, our results demonstrate for the first time the presence of a re-entrant condensation behavior for LPS molecules, which can be exploited for developing novel membrane-perturbing agents based on multivalent ions as efficient GNB antibiotics.


Assuntos
Bactérias Gram-Negativas , Lipopolissacarídeos , Cátions Bivalentes/química , Lipopolissacarídeos/química , Bactérias Gram-Negativas/química , Cátions Monovalentes , Antibacterianos
14.
Nanoscale Adv ; 4(11): 2412-2419, 2022 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-36134138

RESUMO

Artificial synapses based on electrolyte gated transistors with conductance modulation characteristics have demonstrated their great potential in emulating the memory functions in the human brain for neuromorphic computing. While previous studies are mostly focused on the emulation of the basic memory functions of homo-synapses using single-gate transistors, multi-gate transistors offer opportunities for the mimicry of more complex and advanced memory formation behaviors in biological hetero-synapses. In this work, we demonstrate an artificial hetero-synapse based on a dual-gate electrolyte transistor that can implement in situ spatiotemporal information integration and storage. We show that electric pulses applied on a single gate or unsynchronized electric pulses applied on dual gates only induce volatile conductance modulation for short-term memory emulation. In contrast, the device integrates the electric pulses coincidently applied on the dual gates in a supralinear manner and exhibits nonvolatile conductance modulation, enabling long-term memory emulation. Further studies prove that artificial neural networks based on such hetero-synaptic transistors can autonomously filter the random noise signals in the dual-gate inputs during spatiotemporal integration, facilitating the formation of accurate and stable memory. Compared to the single-gate synaptic transistor, the classification accuracy of MNIST handwritten digits using the hetero-synaptic transistor is improved from 89.3% to 99.0%. These findings demonstrate the great potential of multi-gate hetero-synaptic transistors in simulating complex spatiotemporal information processing functions and provide new platforms for the design of advanced neuromorphic computing systems.

15.
Molecules ; 27(15)2022 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-35897851

RESUMO

Among nitrogen-containing cationic electrolytes, diallyl quaternary ammonium salt is a typical monomer with the highest positive charge density, which has attracted the most attention, especially in the research on homopolymers and copolymers of dimethyl diallyl ammonium chloride (DMDAAC), which occupy a very unique and important position. In order to improve the lipophilicity of substituted diallyl ammonium chloride monomers under the premise of high cationic charge density, the simplest, most direct, and most efficient structure design strategy was selected in this paper. Only one of the substituents on DMDAAC quaternary ammonium nitrogen was modified by alkyl; the substituents were propyl and amyl groups, and their corresponding monomers were methyl propyl diallyl ammonium chloride (MPDAAC) and methyl amyl diallyl ammonium chloride (MADAAC), respectively. The effect of substituent structure on the homopolymerization activity of methyl alkyl diallyl ammonium chloride was illustrated by quantum chemical calculation and homopolymerization rate determination experiments via ammonium persulfate (APS) as the initiator system. The results of quantum chemistry simulation showed that, with the finite increase in substituted alkyl chain length, the numerical values of the bond length and the charge distribution of methyl alkyl diallyl ammonium chloride monomer changed little, with the activation energy of the reactions in the following order: DMDAAC < MPDAAC < MADAAC. The polymerization activities measured by the dilatometer method were in the order DMDAAC > MPDAAC > MADAAC. The activation energies Ea of homopolymerization were 96.70 kJ/mol, 97.25 kJ/mol, and 100.23 kJ/mol, and the rate equation of homopolymerization of each monomer was obtained. After analyzing and comparing these results, it could be easily found that the electronic effect of substituent was not obvious, whereas the effect of the steric hindrance was dominant. The above studies have laid a good foundation for an understanding of the polymerization activity of methyl alkyl diallyl ammonium chloride monomers and the possibility of preparation and application of these polymers with high molecular weight.


Assuntos
Compostos de Amônio , Polímeros , Cloreto de Amônio/farmacologia , Nitrogênio , Polimerização , Polímeros/química
16.
Polymers (Basel) ; 14(14)2022 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-35890587

RESUMO

Poly(3-methacrylamido propyl trimethyl ammonium chloride) (PMAPTAC) is a typical cationic water-soluble polyelectrolyte, which has been widely used in petroleum, papermaking, daily cosmetics and other fields in the form of an aqueous solution. However, the acid-base and thermal stability of PMAPTAC in aqueous solution have not been reported yet, which hinders its further application in high-temperature and acid-base environments. To address these deficiencies, the effects of temperature and pH of PMAPTAC with different intrinsic viscosities on its hydrolysis stability were investigated qualitatively and quantitatively, and the hydrolysis mechanism was studied. Firstly, the qualitative analysis showed that the apparent viscosity of the PMAPTAC solution decreased with hydrolysis time at different temperatures and pH. The higher the temperature and the lower the pH, the greater the viscosity loss of PMAPTAC. The quantitative analysis showed that the hydrolysis rate of the PMAPTAC sample solution increased with the increase in temperature and pH. In addition, the intrinsic viscosity of PMAPTAC samples had little effect on the hydrolytic stability of PMAPTAC. Secondly, by analyzing the viscosity curves at different pH and temperatures by Arrhenius analysis, the Arrhenius equations were found to be 1/τ = 200.34e^((-25.04)/RT), 1/τ = 9127.07e^((-38.90)/RT) and 1/τ = 4683.03e^((-39.89)/RT) for pH 3, pH 7 and pH 11, respectively. Thirdly, the hydrolysis rate of PDMC was the fastest under alkaline conditions. In addition, compared with PDMC, PMAPTAC had better hydrolysis stability under the same conditions. Finally, the mechanism of the hydrolyzed polymer was studied by FTIR and 13CNMR, which showed that the carbonyl group of PMAPTAC was hydrolyzed into a carboxyl group, and the small molecule (3-aminopropyl) trimethylammonium chloride was generated, while the ester group of PDMC was hydrolyzed into a carboxyl group, and choline chloride was released. The above results can provide a theoretical basis for the application of PMAPTAC in some high-temperature and acid-base environments.

17.
Comput Biol Med ; 144: 105366, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35305503

RESUMO

In recent years, low-power and wearable biomedical testing devices have emerged as a key answer to the challenges associated with epilepsy disorders, which are prone to crises and require prolonged monitoring. The feature vector of the electroencephalographic (EEG) signal was extracted using the lifting wavelet transform algorithm, and the hardware of the lifting wavelet transform module was optimized using the canonic signed digit (CSD) coding method. A low-power EEG feature extraction circuit with a power consumption of 0.42 mW was constructed. This article employs the support vector machine (SVM) technique after feature extraction to categorize and identify epilepsy. A parallel SVM processing unit was constructed to accelerate classification and identification, and then a high-speed, low-power EEG epilepsy detection processor was implemented. The processor design was completed using TSMC 65 nm technology. The chip size is 0.98 mm2, operating voltage is 1 V, operating frequency is 1 MHz, epilepsy detection latency is 0.91 s, power consumption is 0.448 mW, and energy efficiency of a single classification is 2.23 µJ/class. The CHB-MIT database test results show that this processor has a sensitivity of 91.86% and a false detection rate of 0.17/h. Compared to other processors, this processor is more suitable for portable/wearable devices.


Assuntos
Epilepsia , Análise de Ondaletas , Algoritmos , Eletroencefalografia/métodos , Epilepsia/diagnóstico , Humanos , Remoção , Processamento de Sinais Assistido por Computador , Máquina de Vetores de Suporte
18.
Molecules ; 27(4)2022 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-35209058

RESUMO

Quaternary ammonium salt polymers, a kind of polyelectrolyte with a quaternary ammonium group, are widely used in traditional and emerging industries due to their good water-solubility, adjustable cationicity and molecular weight, high efficiency and nontoxicity. In this paper, firstly, the properties and several synthesis methods of typical quaternary ammonium salt monomers were introduced. Secondly, the research progress on the synthesis of polymers was summarized from the perspective of obtaining products with high molecular weight, narrow molecular weight distribution and high monomer conversion, and special functional polymers. Thirdly, the relationships between the structures and properties of the polymer were analyzed from the perspectives of molecular weight, charge density, structural stability, and microstructural regulation of the polymer chain unit. Fourthly, typical examples of quaternary ammonium salt polymers in the application fields of water treatment, daily chemicals, petroleum exploitation, papermaking, and textile printing and dyeing were listed. Finally, constructive suggestions were put forward on developing quaternary ammonium salt polymers with high molecular weights, strengthening the research on the relationships between the structures and their properties and pinpointing relevant application fields.

19.
Soft Matter ; 17(48): 10862-10872, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34806740

RESUMO

The charge regulation and the release of counterions are extremely important and substantial in determining the charge state of polyelectrolytes and the interaction between polyelectrolytes and proteins. Going beyond monovalent to multivalent cations, it is well-known that the effects of ions are qualitatively different. Therefore, the well-accepted descriptions of the charge regulation and the counterion release based on monovalent ions do not immediately apply to systems with multivalent ions. Here, we study the key structural and electrostatic features of charged dendrimers at hand of the pharmaceutically important dendritic polyglycerol sulfate (dPGS) macromolecule equilibrated with monovalent and divalent salts by molecular dynamics (MD) simulations. Following a simple but accurate scheme to determine its effective radius, the counterion condensed layer of the dPGS is determined with high accuracy and we observe the sequential replacement of condensed monovalent cations (MCs) to divalent cations (DCs) rendering a smaller dPGS effective charge versus the DC concentration. We resolve and track the release of counterions on the dPGS along its binding pathway with the plasma protein Human Serum Albumin (HSA). We find that the release of MCs remains favorable for the complexation leading to a considerable amount of release entropy as the driving force for complexation. The release of DCs only occurs above a certain DC concentration with a comparably smaller number of released ions than MCs. Its contribution to the binding free energy is small indicating a subtle cancellation between the entropy gain in releasing DCs and the enthalpy penalty from dissociating DCs from the dendrimer.


Assuntos
Simulação de Dinâmica Molecular , Entropia , Humanos , Polieletrólitos , Eletricidade Estática , Termodinâmica
20.
Front Neurosci ; 15: 717222, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34602968

RESUMO

The interference of noise will cause the degradation of image quality, which can have a negative impact on the subsequent image processing and visual effect. Although the existing image denoising algorithms are relatively perfect, their computational efficiency is restricted by the performance of the computer, and the computational process consumes a lot of energy. In this paper, we propose a method for image denoising and recognition based on multi-conductance states of memristor devices. By regulating the evolution of Pt/ZnO/Pt memristor wires, 26 continuous conductance states were obtained. The image feature preservation and noise reduction are realized via the mapping between the conductance state and the image pixel. Furthermore, weight quantization of convolutional neural network is realized based on multi-conductance states. The simulation results show the feasibility of CNN for image denoising and recognition based on multi-conductance states. This method has a certain guiding significance for the construction of high-performance image noise reduction hardware system.

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