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1.
Artigo em Inglês | MEDLINE | ID: mdl-35312418

RESUMO

A graphitic carbon nitride was synthesised and nalidixic acid (NA) based molecularly imprinted microspheres (MIMs) were polymerised on its surface to create a composite material. After characterisation and evaluation of its absorption ability, the composite was used to prepare a solid-phase extraction (SPE) cartridge for purification of fluoroquinolones in chicken muscle, analysed by ultra-performance liquid chromatography. The cartridge showed high absorption capacities (378-559 µg) and high recoveries (92.1-99.4%) for eight fluoroquinolones, and could be reused at least 20 times. The limits of detection for the 8 drugs were 0.2-0.8 ng g-1, and recoveries from standard fortified blank chicken muscle samples were 71.9-96.8%. This is the first study reporting the use of molecularly imprinted graphitic carbon nitride composite to determine the residue of veterinary drug in foods of animal origin.

2.
ACS Appl Mater Interfaces ; 14(8): 9945-9969, 2022 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-35167743

RESUMO

The giant magnetoresistance (GMR) effect has seen flourishing development from theory to application in the last three decades since its discovery in 1988. Nowadays, commercial devices based on the GMR effect, such as hard-disk drives, biosensors, magnetic field sensors, microelectromechanical systems (MEMS), etc., are available in the market, by virtue of the advances in state-of-the-art thin-film deposition and micro- and nanofabrication techniques. Different types of GMR biosensor arrays with superior sensitivity and robustness are available at a lower cost for a wide variety of biomedical applications. In this paper, we review the recent advances in GMR-based biomedical applications including disease diagnosis, genotyping, food and drug regulation, brain and cardiac mapping, etc. The GMR magnetic multilayer structure, spin valve, and magnetic granular structure, as well as fundamental theories of the GMR effect, are introduced at first. The emerging topic of flexible GMR for wearable biosensing is also included. Different GMR pattern designs, sensor surface functionalization, bioassay strategies, and on-chip accessories for improved GMR performances are reviewed. It is foreseen that combined with the state-of-the-art complementary metal-oxide-semiconductor (CMOS) electronics, GMR biosensors hold great promise in biomedicine, particularly for point-of-care (POC) disease diagnosis and wearable devices for real-time health monitoring.


Assuntos
Técnicas Biossensoriais , Sistemas Microeletromecânicos , Dispositivos Eletrônicos Vestíveis , Eletrônica , Magnetismo
3.
J Agric Food Chem ; 70(9): 3023-3032, 2022 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-35225617

RESUMO

In this study, a type of magnetic photoaffinity-labeled activity-based protein profiling probe for sulfonamide drugs was first synthesized for the purpose of capturing the natural dihydropteroate synthase of Escherichia coli by using simple incubation and magnetic separation. After characterization of its identity with LC-ESI-MS/MS, this enzyme was used as a recognition reagent to develop a direct competitive pseudo-ELISA for the determination of the residues of 40 sulfonamides in pork. Because of the use of streptavidin-horseradish peroxidase and biotinylated horseradish peroxidase as a signal-amplified system, the limits of detection for the 40 drugs were in the range of 0.001-0.016 ng/mL. Compared to the steps in a conventional assay formation, the operation steps were the same, but the sensitivities increased 32-88-fold. Furthermore, the assay performances were better than the previously reported immunoassays performances for sulfonamides. Therefore, this method could be used as a practical tool for multiscreening the trace levels of sulfonamides residues in food samples.


Assuntos
Carne de Porco , Carne Vermelha , Animais , Di-Hidropteroato Sintase/química , Di-Hidropteroato Sintase/metabolismo , Imunoensaio/métodos , Carne Vermelha/análise , Sulfonamidas/química , Suínos , Espectrometria de Massas em Tandem
4.
Nano Lett ; 22(2): 622-629, 2022 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-34982564

RESUMO

Perpendicular magnetic tunnel junctions (p-MTJs) switched utilizing bipolar electric fields have extensive applications in energy-efficient memory and logic devices. Voltage-controlled magnetic anisotropy linearly lowers the energy barrier of the ferromagnetic layer via the electric field effect and efficiently switches p-MTJs only with a unipolar behavior. Here, we demonstrate a bipolar electric field effect switching of 100 nm p-MTJs with a synthetic antiferromagnetic free layer through voltage-controlled exchange coupling (VCEC). The switching current density, ∼1.1 × 105 A/cm2, is 1 order of magnitude lower than that of the best-reported spin-transfer torque devices. Theoretical results suggest that the electric field induces a ferromagnetic-antiferromagnetic exchange coupling transition of the synthetic antiferromagnetic free layer and generates a fieldlike interlayer exchange coupling torque, which causes the bidirectional magnetization switching of p-MTJs. These results could eliminate the major obstacle in the development of spin memory devices beyond their embedded applications.

5.
J Neural Eng ; 19(1)2022 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-35030549

RESUMO

Objective.The objective of this study was to measure the effect of micromagnetic stimulation (µMS) on hippocampal neurons, by using single microcoil (µcoil) prototype, magnetic pen (MagPen). MagPen will be used to stimulate the CA3 region magnetically and excitatory post synaptic potential (EPSP) response measurements will be made from the CA1 region. The threshold for micromagnetic neurostimulation as a function of stimulation frequency of the current driving theµcoil will be demonstrated. Finally, the optimal stimulation frequency of the current driving theµcoil to minimize power will be estimated.Approach.A biocompatible, watertight, non-corrosive prototype, MagPen was built, and customized such that it is easy to adjust the orientation of theµcoil and its distance over the hippocampal tissue in anin vitrorecording setting. Finite element modeling of theµcoil design was performed to estimate the spatial profiles of the magnetic flux density (in T) and the induced electric fields (in V m-1). The induced electric field profiles generated at different values of current applied to theµcoil can elicit a neuronal response, which was validated by numerical modeling. The modeling settings for theµcoil were replicated in experiments on rat hippocampal neurons.Main results.The preferred orientation of MagPen over the Schaffer Collateral fibers was demonstrated such that they elicit a neuron response. The recorded EPSPs from CA1 region due toµMS at CA3 region were validated by applying tetrodotoxin (TTX). Application of TTX to the hippocampal slice blocked the EPSPs fromµMS while after prolonged TTX washout, a partial recovery of the EPSP fromµMS was observed. Finally, it was interpreted through numerical analysis that increasing frequency of the current driving theµcoil, led to a decrease in the current amplitude threshold for micromagnetic neurostimulation.Significance.This work reports that micromagnetic neurostimulation can be used to evoke population EPSP responses in the CA1 region of the hippocampus. It demonstrates the strength-frequency curve forµMS and its unique features related to orientation dependence of theµcoils, spatial selectivity and stimulation threshold related to distance dependence. Finally, the challenges related toµMS experiments were studied including ways to overcome them.


Assuntos
Hipocampo , Neurônios , Animais , Estimulação Elétrica , Potenciais Pós-Sinápticos Excitadores , Hipocampo/fisiologia , Fenômenos Magnéticos , Ratos , Sinapses/fisiologia , Transmissão Sináptica
6.
Nanotechnology ; 33(18)2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-35013010

RESUMO

In the treatment of neurodegenerative, sensory and cardiovascular diseases, electrical probes and arrays have shown quite a promising success rate. However, despite the outstanding clinical outcomes, their operation is significantly hindered by non-selective control of electric fields. A promising alternative is micromagnetic stimulation (µMS) due to the high permeability of magnetic field through biological tissues. The induced electric field from the time-varying magnetic field generated by magnetic neurostimulators is used to remotely stimulate neighboring neurons. Due to the spatial asymmetry of the induced electric field, high spatial selectivity of neurostimulation has been realized. Herein, some popular choices of magnetic neurostimulators such as microcoils (µcoils) and spintronic nanodevices are reviewed. The neurostimulator features such as power consumption and resolution (aiming at cellular level) are discussed. In addition, the chronic stability and biocompatibility of these implantable neurostimulator are commented in favor of further translation to clinical settings. Furthermore, magnetic nanoparticles (MNPs), as another invaluable neurostimulation material, has emerged in recent years. Thus, in this review we have also included MNPs as a remote neurostimulation solution that overcomes physical limitations of invasive implants. Overall, this review provides peers with the recent development of ultra-low power, cellular-level, spatially selective magnetic neurostimulators of dimensions within micro- to nano-range for treating chronic neurological disorders. At the end of this review, some potential applications of next generation neuro-devices have also been discussed.


Assuntos
Estimulação Elétrica , Campos Magnéticos , Estimulação Elétrica/instrumentação , Humanos , Neuroestimuladores Implantáveis , Nanopartículas de Magnetita/uso terapêutico , Doenças do Sistema Nervoso/terapia
7.
J Agric Food Chem ; 69(46): 13953-13963, 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34783550

RESUMO

In this study, the dihydropteroate synthase of Staphylococcus aureus was obtained, and its recognition mechanisms for 31 sulfonamide drugs were studied. Results showed that their core structure matched well with the binding pocket of para-aminobenzoic acid, and all the sulfonamide side chains were out of the binding pocket. Hydrogen bonds and hydrophobic interactions were the main intermolecular forces, and the key amino acids were Gly171 and Lys203. The binding sites in sulfonamide molecules were mainly around the para-aminobenzenesulfonamide part. This enzyme was used to develop a fluorescence polarization assay for detection of these drugs in chicken muscles. The change trends of half of inhibition concentrations and cross-reactivities for the 31 drugs were identical with the receptor-ligand affinities. The limits of detection were in the range of 2.0-38.5 ng/g, and one assay could be finished within several minutes. Therefore, this method could be used for multiscreening of sulfonamide residues in meat samples.


Assuntos
Di-Hidropteroato Sintase , Sulfonamidas , Ácido 4-Aminobenzoico , Sítios de Ligação , Di-Hidropteroato Sintase/metabolismo , Polarização de Fluorescência
8.
BMJ Open ; 11(10): e043790, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34598979

RESUMO

OBJECTIVES: As early prediction of severe illness and death for patients with coronavirus disease 2019 (COVID-19) is important, we aim to explore the clinical value of laboratory indicators in evaluating the progression and prognosis of patients with COVID-19. DESIGN: Retrospective cohort study. SETTING: Hospital-based study in China. PARTICIPANTS: Adult patients with COVID-19 from December 15, 2019 to March 15, 2020. END POINT: Disease severity and mortality. METHODS: Clinical data of 638 patients with COVID-19 were collected and compared between severe and non-severe groups. The predictive ability of laboratory indicators in disease progression and prognosis of COVID-19 was analysed using the receiver operating characteristic curve. The survival differences of COVID-19 patients with different levels of laboratory indicators were analysed utilising Kaplan-Meier analysis. RESULTS: 29.8% (190/638) of patients with COVID-19 progressed to severe. Compared with patients with no adverse events, C reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR) and D-dimer were significantly higher in severe patients with adverse events, such as acute myocardial injury, respiratory failure, acute kidney injury, mechanical ventilation, intensive care unit admission, multiple organ dysfunction syndromes and death (all p<0.05). The multivariate logistic analysis suggested that CRP, NLR and D-dimer were independent risk factors for the disease progression of COVID-19 (all p<0.05). The model combining all of them owned the highest area under the receiver operating characteristic curve (AUC) predicting disease progression and death of COVID-19, with AUC of 0.894 (95% CI 0.857 to 0.931) and 0.918 (95% CI 0.873 to 0.962), respectively. Survival analysis suggested that the patients with a high level of CRP, NLR or D-dimer performed shorter overall survival time (all p<0.05). CONCLUSIONS: The combination of CRP, NLR and D-dimer could be an effective predictor for the aggravation and death in patients with COVID-19. The abnormal expression of these indicators might suggest a strong inflammatory response and multiple adverse events in patients with severe COVID-19.


Assuntos
COVID-19 , Laboratórios , Adulto , Progressão da Doença , Humanos , Neutrófilos , Prognóstico , Curva ROC , Estudos Retrospectivos , SARS-CoV-2
9.
ACS Appl Mater Interfaces ; 13(37): 44136-44146, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34499464

RESUMO

With the ongoing global pandemic of coronavirus disease 2019 (COVID-19), there is an increasing quest for more accessible, easy-to-use, rapid, inexpensive, and high-accuracy diagnostic tools. Traditional disease diagnostic methods such as qRT-PCR (quantitative reverse transcription-PCR) and ELISA (enzyme-linked immunosorbent assay) require multiple steps, trained technicians, and long turnaround time that may worsen the disease surveillance and pandemic control. In sight of this situation, a rapid, one-step, easy-to-use, and high-accuracy diagnostic platform will be valuable for future epidemic control, especially for regions with scarce medical resources. Herein, we report a magnetic particle spectroscopy (MPS) platform for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) biomarkers: spike and nucleocapsid proteins. This technique monitors the dynamic magnetic responses of magnetic nanoparticles (MNPs) and uses their higher harmonics as a measure of the nanoparticles' binding states. By anchoring polyclonal antibodies (pAbs) onto MNP surfaces, these nanoparticles function as nanoprobes to specifically bind to target analytes (SARS-CoV-2 spike and nucleocapsid proteins in this work) and form nanoparticle clusters. This binding event causes detectable changes in higher harmonics and allows for quantitative and qualitative detection of target analytes in the liquid phase. We have achieved detection limits of 1.56 nM (equivalent to 125 fmole) and 12.5 nM (equivalent to 1 pmole) for detecting SARS-CoV-2 spike and nucleocapsid proteins, respectively. This MPS platform combined with the one-step, wash-free, nanoparticle clustering-based assay method is intrinsically versatile and allows for the detection of a variety of other disease biomarkers by simply changing the surface functional groups on MNPs.


Assuntos
COVID-19/virologia , Nanopartículas/química , Proteínas do Nucleocapsídeo/química , SARS-CoV-2/química , Análise Espectral/métodos , Glicoproteína da Espícula de Coronavírus/química , Análise por Conglomerados , Humanos
10.
Poult Sci ; 100(10): 101390, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34391965

RESUMO

In this study, 105 broiler chickens were fed with dietary feeds containing different contents of Dichroae Radix extract for 10 consecutive days. Then the residue depletions of its main alkaloids (febrifugine and isofebrifugine) in muscle, kidney and liver samples at different withdrawal times were determined by an ultra-performance liquid chromatography method. Results showed that the 2 alkaloids were mainly at tissue-bound formation. At withdrawal period of 0 d, their concentrations in all samples were high but decreased rapidly after 1 day of cessation (35-91%). After 5 to 7 days of cessation, their residues in muscle and kidney were not detectable, and after at least 10 days of cessation they were not detectable in liver. These results indicated that an appropriate withdrawal time for Dichroae Radix preparation was required if it is licensed as a new drug, and the best target tissue for monitoring its residue was liver.


Assuntos
Galinhas , Resíduos de Drogas , Animais , Resíduos de Drogas/análise , Fígado , Carne/análise , Piperidinas , Quinazolinas
11.
Nat Nanotechnol ; 16(9): 981-988, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34326528

RESUMO

Voltage control of magnetic order is desirable for spintronic device applications, but 180° magnetization switching is not straightforward because electric fields do not break time-reversal symmetry. Ferrimagnets are promising candidates for 180° switching owing to a multi-sublattice configuration with opposing magnetic moments of different magnitudes. In this study we used solid-state hydrogen gating to control the ferrimagnetic order in rare earth-transition metal thin films dynamically. Electric field-induced hydrogen loading/unloading in GdCo can shift the magnetic compensation temperature by more than 100 K, which enables control of the dominant magnetic sublattice. X-ray magnetic circular dichroism measurements and ab initio calculations indicate that the magnetization control originates from the weakening of antiferromagnetic exchange coupling that reduces the magnetization of Gd more than that of Co upon hydrogenation. We observed reversible, gate voltage-induced net magnetization switching and full 180° Néel vector reversal in the absence of external magnetic fields. Furthermore, we generated ferrimagnetic spin textures, such as chiral domain walls and skyrmions, in racetrack devices through hydrogen gating. With gating times as short as 50 µs and endurance of more than 10,000 cycles, our method provides a powerful means to tune ferrimagnetic spin textures and dynamics, with broad applicability in the rapidly emerging field of ferrimagnetic spintronics.

12.
J Asian Nat Prod Res ; : 1-7, 2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34236260

RESUMO

A new pair of enantiomeric isoprenylated chromone derivatives, (±)-pestaloficiol X [(±)-1], along with a known compound pestaloficiol J (2), were isolated from the plant endophytic fungus Pestalotiopsis sp. The racemic mixture 1 was separated through chiral HPLC. The structures of new compounds (±)-1 were elucidated on the basis of extensive spectroscopic data and their absolute configurations were further configured through computational analysis of their electronic circular dichroism (ECD) spectra. Compound (+)-1 showed significant inhibitory potency against HL-60 and HEP-3B cell lines, with IC50 values of 1.35 ± 0.15 and 3.70 ± 0.33 µM, respectively, while compound (-)-1 showed significant inhibitory potency against HL-60 and HEP-3B cell lines, with IC50 values of 2.39 ± 0.26 and 2.99 ± 0.35 µM, respectively.

13.
World J Clin Cases ; 9(20): 5737-5743, 2021 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-34307633

RESUMO

BACKGROUND: Adrenocortical carcinoma (ACC) is a rare malignant epithelial tumor originating from adrenocortical cells that carries a very poor prognosis. Metastatic or inoperable diseases are often considered incurable, and treatment remains a challenge. Especially for advanced cases such as ACC complicated with renal venous cancer thrombus, there are few cumulative cases in the literature. CASE SUMMARY: The patient in this case was a 39-year-old middle-aged male who was admitted to the hospital for more than half a month due to dizziness and chest tightness. Computed tomography (CT) findings after admission revealed a left retroperitoneal malignant space-occupying lesion, but the origin of the formation of the left renal vein cancer thrombus remained to be determined. It was speculated that it originated from the left adrenal gland, perhaps a retroperitoneal source, and left adrenal mass + left nephrectomy + left renal vein tumor thrombus removal + angioplasty were performed under general anesthesia. Postoperative pathology results indicated a diagnosis of ACC. Postoperative steroid therapy was administered. At 3 mo after surgery, abdominal CT reexamination revealed multiple enlarged retroperitoneal lymph nodes and multiple low-density shadows in the liver, and palliative radiotherapy and mitotane were administered, considering the possibility of metastasis. The patient is currently being followed up. CONCLUSION: ACC is a highly malignant tumor. Even if the tumor is removed surgically, there is still the possibility of recurrence. Postoperative mitotane and adjuvant chemoradiotherapy have certain benefits for patients, but they cannot fully offset the poor prognosis of this disease.

14.
Luminescence ; 36(7): 1767-1774, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34270836

RESUMO

In this study, nitrobenzene was used as dummy template to synthesize a type of specific molecularly imprinted microspheres for chloramphenicol, and 4-nitroaniline was coupled with three fluorophores to synthesize three fluorescent tracers. Then a competitive fluorescence method was developed on a conventional microplate for detection of chloramphenicol in chicken and pork samples. This method contained only one sample-loading step, so one assay was finished within 30 min. The IC50 was 1.8 ng/ml, and the limit of detection was 0.06 ng/g. The recoveries from chloramphenicol-fortified blank meat samples were in the range 67.5-96.2%. Furthermore, this method could be recycled three times. The detection results for some real meat samples were identical to that of a LC-MS/MS method. Therefore, this method could be used as a practical tool for routine screening for the residue of chloramphenicol in large number of meat samples.


Assuntos
Cloranfenicol , Impressão Molecular , Cloranfenicol/análise , Cromatografia Líquida , Carne/análise , Microesferas , Espectrometria de Massas em Tandem
15.
Artigo em Inglês | MEDLINE | ID: mdl-33989121

RESUMO

In this study, molecularly imprinted microspheres of a type capable of recognising amantadine and rimantadine were first synthesised, and three fluorescent tracers based on dansyl chloride, fluorescein isothiocyanate and 5-carboxytetramethylrhodamine were also synthesised. These reagents were used to develop and optimise a direct competitive fluorescence method on conventional 96-well microplate for detection of the two analytes. Results showed that this method achieved simple operation procedure, rapid assay process (30 min), high sensitivity (limits of detection 0.04-0.05 ng mL-1) and acceptable recycle performance (five times). After optimisation of several parameters, this method was used to detect amantadine and rimantadine in chicken muscle samples. Their recoveries from standards fortified blank samples were in the range of 62.3-93.7%. The analysis results for some real chicken samples were consistent with a confirmatory LC-MS/MS method. Therefore, this method could be used as a rapid, simple and accurate tool for routine screening the residues of amantadine and rimantadine in a large number of chicken muscle samples.


Assuntos
Amantadina/análise , Microesferas , Impressão Molecular , Rimantadina/análise , Animais , Galinhas , Estrutura Molecular , Músculos/química , Espectrometria de Fluorescência
16.
BMC Med Inform Decis Mak ; 21(1): 121, 2021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33832470

RESUMO

BACKGROUND: The motion capture has been used as the usual method for measuring movement parameters of human, and most of the measuring data are obtained by partial manual process based on commercial software. An automatic kinematics data process was developed by programming on MATLAB software in this paper. METHODS: The motion capture measurement of healthy volunteers was carried out and the MATLAB program was used for data process. Firstly, the coordinate data of markers and anatomical points on human lower limb measured by motion capture system were read and repaired through the usual and the patch program. Meantime, the local coordinate systems of human femur and tibia were established with anatomical points. Then flexion/extension, abduction/adduction and internal/external rotation of human knee tibiofemoral joint were obtained by special coordinate transformation program. RESULTS: Using the above methods, motion capture measurements and batch data processing were carried out on squatting and climbing stairs of 29 healthy volunteers. And the motion characteristics (flexion/extension, internal/external rotation and adduction/abduction) of the knee joint were obtained. For example, the maximum internal/external rotation in squatting and climbing stairs were respectively was 30.5 degrees and 14 degrees, etc. Meantime, the results of this paper also were respectively compared with the results processed by other research methods, and the results were basically consistent, thus the reliability of our research method was verified. After calibration processing, the compiled MATLAB program of this paper can directly be used for efficient batch processing and avoiding manual modeling one by one. CONCLUSION: A novel Patch Program of this paper has been developed, which can make reasonable compensation for missing and noise signals to obtain more complete motion data. At the same time, a universal data processing program has also been developed for obtaining the relative movement of various components of the human body, and the program can be modified for detail special analysis. These motion capture technologies can be used to judge whether the human body functions are abnormal, provide a reference for rehabilitation treatment and design of rehabilitation equipment, and evaluate the effectiveness before and after surgery.


Assuntos
Artroplastia do Joelho , Fenômenos Biomecânicos , Humanos , Articulação do Joelho/cirurgia , Amplitude de Movimento Articular , Reprodutibilidade dos Testes , Rotação
17.
ACS Omega ; 6(9): 6274-6283, 2021 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-33718717

RESUMO

Magnetic nanoparticles (MNPs) have been extensively used as tiny heating sources in magnetic hyperthermia therapy, contrast agents in magnetic resonance imaging, tracers in magnetic particle imaging, carriers for drug/gene delivery, etc. There have emerged many MNP/microbead suppliers since the past decade, such as Ocean NanoTech, Nanoprobes, US Research Nanomaterials, Miltenyi Biotec, micromod Partikeltechnologie GmbH, nanoComposix, and so forth. In this paper, we report the physical and magnetic characterizations on iron oxide nanoparticle products from Ocean NanoTech. Standard characterization tools such as vibrating-sample magnetometry, X-ray diffraction, dynamic light scattering, transmission electron microscopy, and zeta potential analysis are used to provide MNP customers and researchers with an overview of these iron oxide nanoparticle products. In addition, the dynamic magnetic responses of these iron oxide nanoparticles in aqueous solutions are investigated under low- and high-frequency alternating magnetic fields, giving a standardized operating procedure for characterizing the MNPs from Ocean NanoTech, thereby yielding the best of MNPs for different applications.

18.
Gastroenterol Rep (Oxf) ; 9(1): 71-76, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33747528

RESUMO

BACKGROUND: Total mesorectum excision (TME) is considered the standard surgical procedure for rectal-cancer treatment. Transanal TME (taTME) is a new procedure to treat low rectal cancer. Some published studies have proven that taTME can provide a better-quality resected specimen in low-rectal-cancer patients in comparison to the transabdominal procedure, yet long-term outcomes must be investigated. We designed this non-inferiority trial (TaLaR trial) to compare short-term and long-term outcomes between taTME and laparoscopic TME (lapTME) for rectal cancer. METHODS: The TaLaR trial is a phase III open-labeled multicenter randomized-controlled trial. Patients who are diagnosed with rectal cancer with no more than T3N2 stage, and with the tumor location below the peritoneal reflection by magnetic resonance imaging scan, digital rectal examination, or colonoscopy, qualify for this study. After calculating, a total of 1,114 patients (557 per group) will be randomly allocated to either the taTME or the lapTME group. Primary endpoints are the 3-year disease-free survival (DFS) rate and the 5-year overall survival (OS) rate. Secondary endpoints include specimen quality, perioperative results, pelvic and anal function, and quality of life. DISCUSSION: The TaLaR trial is expected to clarify whether taTME can achieve comparable oncological outcomes, as well as improve specimen quality and recovery conditions in rectal-cancer patients compared with lapTME.

19.
Phys Rev Lett ; 126(10): 106601, 2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33784124

RESUMO

We propose a novel approach to achieve a giant anomalous Hall effect (AHE) in materials with flat bands (FBs). FBs are accompanied by small electronic bandwidths, which consequently increases the momentum separation (K) within pair of Weyl points and, thus, the integrated Berry curvature. Starting from a simple model with a single pair of Weyl nodes, we demonstrated the increase of K and the AHE by decreasing the bandwidth. It is further expanded to a realistic pyrochlore lattice model with characteristic double-degenerated FBs, where we discovered a giant AHE while maximizing the K with nearly vanishing band dispersion of FBs. We identify that such a model system can be realized and modulated through strain engineering in both pyrochlore and spinel compounds based on first-principles calculations, validating our theoretical model and providing a feasible platform for experimental exploration.

20.
Hortic Res ; 8(1): 32, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33518702

RESUMO

The aroma of peach fruit is predominantly determined by the accumulation of γ-decalactone and ester compounds. A previous study showed that the biosynthesis of these aroma compounds in peach fruit is catalyzed by PpAAT1, an alcohol acyltransferase. In this work, we investigated the key active site residues responsible for γ-decalactone and ester biosynthesis. A total of 14 candidate amino acid residues possibly involved in internal esterification and 9 candidate amino acid residues possibly involved in esterification of PpAAT1 were assessed via site-directed mutagenesis. Analyses of the in vitro enzyme activities of PpAAT1 and its site-directed mutant proteins (PpAAT1-SMs) with different amino acid residue mutations as well as the contents of γ-decalactone in transgenic tobacco leaves and peach fruits transiently expressing PpAAT1 and PpAAT1-SMs revealed that site-directed mutation of H165 in the conserved HxxxD motif led to lost enzymatic activity of PpAAT1 in both internal esterification and its reactions, whereas mutation of the key amino acid residue D376 led to the total loss of γ-decalactone biosynthesis activity of PpAAT1. Mutations of 9 and 7 other amino acid residues also dramatically affected the enzymatic activity of PpAAT1 in the internal esterification and esterification reactions, respectively. Our findings provide a biochemical foundation for the mechanical biosynthesis of γ-decalactone and ester compounds catalyzed by PpAAT1 in peach fruits, which could be used to guide the molecular breeding of new peach species with more favorable aromas for consumers.

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