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1.
ACS Omega ; 9(8): 9702-9713, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38434859

RESUMO

Potassium ion channels are the structural basis for excitation transmission, heartbeat, and other biological processes. The selectivity filter is a critical structural component of potassium ion channels, whose structure is crucial to realizing their function. As biomolecules vibrate and rotate at frequencies in the terahertz band, potassium ion channels are sensitive to terahertz waves. Therefore, it is worthwhile to investigate how the terahertz wave influences the selectivity filter of the potassium channels. In this study, we investigate the structure of the selectivity filter of Kv1.2 potassium ion channels using molecular dynamics simulations. The effect of an electric field on the channel has been examined at four different resonant frequencies of the carbonyl group in SF: 36.75 37.06, 37.68, and 38.2 THz. As indicated by the results, 376GLY appears to be the critical residue in the selectivity filter of the Kv1.2 channel. Its dihedral angle torsion is detrimental to the channel structural stability and the transmembrane movement of potassium ions. 36.75 THz is the resonance frequency of the carbonyl group of 376GLY. Among all four frequencies explored, the applied terahertz electric field of this frequency has the most significant impact on the channel structure, negatively impacting the channel stability and reducing the ion permeability by 20.2% compared to the absence of fields. In this study, we simulate that terahertz waves in the mid-infrared frequency region can significantly alter the structure and function of potassium ion channels and that the effects of terahertz waves differ greatly based on frequency.

2.
Math Biosci Eng ; 21(1): 1394-1412, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38303470

RESUMO

In response to the limited capability of extracting semantic information in knowledge graph completion methods, we propose a model that combines spatial transformation and attention mechanisms (STAM) for knowledge graph embedding. Firstly, spatial transformation is applied to reorganize entity embeddings and relation embeddings, enabling increased interaction between entities and relations while preserving shallow information. Next, a two-dimensional convolutional neural network is utilized to extract complex latent information among entity relations. Simultaneously, a multi-scale channel attention mechanism is constructed to enhance the capture of local detailed features and global semantic features. Finally, the surface-level shallow information and latent information are fused to obtain feature embeddings with richer semantic expression. The link prediction results on the public datasets WN18RR, FB15K237 and Kinship demonstrate that STAM achieved improvements of 8.8%, 10.5% and 6.9% in the mean reciprocal rank (MRR) evaluation metric compared to ConvE, for the respective datasets. Furthermore, in the link prediction experiments on the hydraulic engineering dataset, STAM achieves better experimental results in terms of MRR, Hits@1, Hits@3 and Hits@10 evaluation metrics, demonstrating the effectiveness of the model in the task of hydraulic engineering knowledge graph completion.

3.
Chemphyschem ; 25(3): e202300851, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38088520

RESUMO

As a material with high specific surface area and excellent chemical stability, graphene exhibited remarkable adsorption and separation performance as well as a wide range of potential applications. The graphene layer played a significant role in influencing gas transmission. In this study, we employed molecular dynamics simulation to investigate the diffusion characteristics and local structures of a mixed system consisting of CH4 , CO2 , SO2 and H2 O. Additionally, we further examined the transformation of the behavior of these mixtures within graphene layers. The order of diffusion coefficients of the four molecules without graphene was H2 O>SO2 >CO2 ≫CH4 . However, in the double-layer graphene, the order changed to CH4 >CO2 ≫H2 O>SO2 . Higher temperatures and lower pressures were found to facilitate gas diffusion. Temperature and pressure had great effects on the local structures of CH4 , CO2 and SO2 , while their impact on H2 O was limited due to the extensive network of hydrogen bonds formed by H2 O molecules. The statistical results of average coordination number revealed that CH4 tended to aggregate with itself, whereas CO2 and SO2 exhibited a tendency to aggregate with H2 O. The graphene structure enhanced the separation and transportation of CH4 from mixed systems.

4.
J Acoust Soc Am ; 154(4): 2440-2452, 2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37850838

RESUMO

Topological elastic wave metamaterials have shown significant advantages in manipulating wave propagation and realizing localized modes. However, topological properties of most mechanical metamaterials are difficult to change because of structural limitations. This work proposes the elastic wave metamaterials with double coupled chains and active control, in which band inversion and topological interface modes can be achieved by flexibly tuning negative capacitance circuits. Finite element simulations and experiments are performed to demonstrate the topological interface modes, which show good agreements with the theoretical results. This research seeks to provide effective strategies for the design and application of topological elastic wave metamaterials.

5.
J Chem Phys ; 159(4)2023 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-37486058

RESUMO

As biomolecules vibrate and rotate in the terahertz band, the biological effects of terahertz electromagnetic fields have drawn considerable attention from the physiological and medical communities. Ion channels are the basis of biological electrical signals, so studying the effect of terahertz electromagnetic fields on ion channels is significant. In this paper, the effect of a terahertz electromagnetic field with three different frequencies, 6, 15, and 25 THz, on the Kv1.2 potassium ion channel was investigated by molecular dynamics simulations. The results show that an electromagnetic field with a 15 THz frequency can significantly enhance the permeability of the Kv1.2 potassium ion channel, which is 1.7 times higher than without an applied electric field. By analyzing the behavior of water molecules, it is found that the electromagnetic field with the 15 THz frequency shortens the duration of frozen and relaxation processes when potassium ions pass through the channel, increases the proportion of the direct knock-on mode, and, thus, enhances the permeability of the Kv1.2 potassium ion channel.

6.
RSC Adv ; 13(31): 21633-21642, 2023 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-37476048

RESUMO

In this study, we prepared a polyacrylonitrile (PAN) composite nanofiber membrane comprising Portulaca oleracea L. extract (POE) and a zinc-based metal-organic framework (MOF) by an in situ growth method as a potentially new type of wound dressing with a slow drug-release effect, to solve the problem of the burst release of drugs in wound dressings. The effects of the MOF and POE doping on the nanofiber membranes were examined using scanning electron microscopy (SEM) and FTIR spectroscopy. SEM analysis revealed the dense and uniform attachment of MOF particles to the surface of the nanofiber membrane, while FTIR spectroscopy confirmed the successful fusion of MOF and POE. Furthermore, investigations into the water contact angle and swelling property demonstrated that the incorporation of the MOF and POE enhanced the hydrophilicity of the material. The results of the in vitro release test showed that the cumulative release rate for PAN/MOF/POE60 decreased from 66.5 ± 2.34% to 32.18 ± 1.31% in the initial 4 h and from 90.54 ± 0.79% to 65.92 ± 1.95% in 72 h compared to PAN/POE, indicating a slowing down of the drug release. In addition, the antimicrobial properties of the fiber membranes were evaluated by the disc diffusion method, and it was evident that the PAN/MOF/POE nanofibers exhibited strong inhibition against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The antioxidant properties of the nanofiber membranes loaded with POE were further validated through the DPPH radical scavenging test. These findings highlight the potential application of the developed nanofiber membranes in wound dressings, offering controlled and sustained drug-release capabilities.

7.
Int J Mol Sci ; 24(12)2023 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-37373419

RESUMO

In this paper, the influence of external terahertz electromagnetic fields with different frequencies of 4 THz, 10 THz, 15 THz, and 20 THz on the permeability of the Kv1.2 voltage-gated potassium ion channel on the nerve cell membrane was studied using the combined model of the "Constant Electric Field-Ion Imbalance" method by molecular dynamics. We found that although the applied terahertz electric field does not produce strong resonance with the -C=O groups of the conservative sequence T-V-G-Y-G amino acid residue of the selective filter (SF) of the channel, it would affect the stability of the electrostatic bond between potassium ions and the carbonyl group of T-V-G-Y-G of SF, and it would affect the stability of the hydrogen bond between water molecules and oxygen atoms of the hydroxyl group of the 374THR side chain at the SF entrance, changing the potential and occupied states of ions in the SF and the occurrence probability of the permeation mode of ions and resulting in the change in the permeability of the channel. Compared with no external electric field, when the external electric field with 15 THz frequency is applied, the lifetime of the hydrogen bond is reduced by 29%, the probability of the "soft knock on" mode is decreased by 46.9%, and the ion flux of the channel is activated by 67.7%. Our research results support the view that compared to "direct knock-on", "soft knock-on" is a slower permeation mode.


Assuntos
Campos Eletromagnéticos , Canais de Potássio de Abertura Dependente da Tensão da Membrana , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Simulação de Dinâmica Molecular , Íons/metabolismo , Permeabilidade , Potássio/metabolismo , Canal de Potássio Kv1.2/química , Canal de Potássio Kv1.5/metabolismo
8.
ACS Omega ; 8(23): 20323-20331, 2023 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-37332800

RESUMO

In recent years, medicinal plant extracts have received remarkable attention due to their wound-healing properties. In this study, polycaprolactone (PCL) electrospun nanofiber membranes incorporated with different concentrations of pomegranate peel extract (PPE) were prepared. The results of the SEM and FTIR experiments demonstrated that the morphology of nanofiber is smooth, fine, and bead-free, and the PPE was well introduced into the nanofiber membranes. Moreover, the outcomes of the mechanical property tests demonstrated that the nanofiber membrane made of PCL and loaded with PPE exhibited remarkable mechanical characteristics, indicating that it could fulfill the essential mechanical requisites for wound dressings. The findings of the in vitro drug release investigations indicated that PPE was instantly released within 20 h and subsequently released gradually over an extended period by the composite nanofiber membranes. Meanwhile, the DPPH radical scavenging test confirmed that the nanofiber membranes loaded with PPE exhibited significant antioxidant properties. Antimicrobial experiments showed higher PPE loading, and the nanofiber membranes showed higher antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans. The results of the cellular experiments showed that the composite nanofiber membranes were nontoxic and promoted the proliferation of L929 cells. In summary, electrospun nanofiber membranes loaded with PPE can be used as a wound dressing.

9.
Hum Reprod ; 38(7): 1390-1398, 2023 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-37140151

RESUMO

STUDY QUESTION: What is the effect of defects in the manchette protein IQ motif-containing N (IQCN) on sperm flagellar assembly? SUMMARY ANSWER: Deficiency in IQCN causes sperm flagellar assembly defects and male infertility. WHAT IS KNOWN ALREADY: The manchette is a transient structure that is involved in the shaping of the human spermatid nucleus and protein transport within flagella. Our group recently reported that the manchette protein IQCN is essential for fertilization. Variants in IQCN lead to total fertilization failure and defective acrosome structure phenotypes. However, the function of IQCN in sperm flagellar assembly is still unknown. STUDY DESIGN, SIZE, DURATION: Fifty men with infertility were recruited from a university-affiliated center from January 2014 to October 2022. PARTICIPANTS/MATERIALS, SETTING, METHODS: Genomic DNA was extracted from the peripheral blood samples of all 50 individuals for whole-exome sequencing. The ultrastructure of the spermatozoa was assessed by transmission electron microscopy. Computer-assisted sperm analysis (CASA) was used to test the parameters of curvilinear velocity (VCL), straight-line velocity (VSL), and average path velocity (VAP). An Iqcn knockout (Iqcn-/-) mouse model was generated by CRISPR-Cas9 technology to evaluate sperm motility and the ultrastructure of the flagellum. Hyperactivation and sperm fertilizing ability were assessed in a mouse model. Immunoprecipitation followed by liquid chromatography-mass spectrometry was used to detect IQCN-binding proteins. Immunofluorescence was used to validate the localization of IQCN-binding proteins. MAIN RESULTS AND THE ROLE OF CHANCE: Biallelic variants in IQCN (c.3913A>T and c.3040A>G; c.2453_2454del) were identified in our cohort of infertile men. The sperm from the affected individuals showed an irregular '9 + 2' structure of the flagellum, which resulted in abnormal CASA parameters. Similar phenotypes were observed in Iqcn-/- male mice. VSL, VCL, and VAP in the sperm of Iqcn-/- male mice were significantly lower than those in Iqcn+/+ male mice. Partial peripheral doublet microtubules (DMTs) and outer dense fibers (ODFs) were absent, or a chaotic arrangement of DMTs was observed in the principal piece and end piece of the sperm flagellum. Hyperactivation and IVF ability were impaired in Iqcn-/- male mice. In addition, we investigated the causes of motility defects and identified IQCN-binding proteins including CDC42 and the intraflagellar transport protein families that regulate flagellar assembly during spermiogenesis. LIMITATIONS, REASONS FOR CAUTION: More cases are needed to demonstrate the relation between IQCN variants and phenotypes. WIDER IMPLICATIONS OF THE FINDINGS: Our findings expand the genetic and phenotypic spectrum of IQCN variants in causing male infertility, providing a genetic marker for sperm motility deficiency and male infertility. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Natural Science Foundation of China (81974230 and 82202053), the Changsha Municipal Natural Science Foundation (kq2202072), the Hunan Provincial Natural Science Foundation (2022JJ40658), and the Scientific Research Foundation of Reproductive and Genetic Hospital of CITIC-Xiangya (YNXM-202114 and YNXM-202201). No conflicts of interest were declared. TRIAL REGISTRATION NUMBER: N/A.


Assuntos
Infertilidade Masculina , Espermatozoides , Animais , Humanos , Masculino , Camundongos , Infertilidade Masculina/genética , Infertilidade Masculina/metabolismo , Sêmen/metabolismo , Motilidade dos Espermatozoides/genética , Cauda do Espermatozoide/metabolismo , Espermatozoides/metabolismo , Espermatozoides/patologia
10.
Am Surg ; 89(5): 1654-1660, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-35068200

RESUMO

BACKGROUND: Anastomotic strictures represent a major source of morbidity in colorectal surgery with an incidence reported up to 30%. Despite this, the mechanism by which strictures develop remains unclear. This study aims to determine the incidence of colorectal anastomotic strictures and associated risk factors among a series of diverted patients. MATERIALS AND METHODS: A retrospective chart review was conducted of 142 patients over a 7-year period at a single institution after colorectal resection with anastomosis and diverting ileostomy creation re-examined with postoperative endoscopy. One patient was removed due to anastomotic tumor recurrence. Patient and technical factors were examined for significance using chi-square analysis. Logistic regression was used to perform multivariate analysis to estimate odds ratio (OR) and 95% confidence intervals (CI). RESULTS: Among 141 patients, 14.1% (20 patients) developed strictures detected on endoscopy. Strictures were observed in a greater percentage of women than men (21.2% vs 8%, P = .025). 30.6% of patients who underwent resections for diverticulitis developed strictures while those with neoplastic lesions and other indications had stricture rates of 6.8% and 17.6%, respectively (P = .002). Anastomoses performed during a colostomy reversal were associated with a higher stricture rate (OR 4.23, 95% CI 1.37-13.40, P = .012). Anastomoses performed with a 28/29 mm EEA circular stapler demonstrated a significantly higher stricture rate versus a 31/33 mm stapler (OR 7.21, 95% CI 1.23-155.58, P = .045). DISCUSSION: Our data reveal that female sex, history of diverticulitis, anastomoses performed in the setting of colostomy reversal, and smaller stapler size are associated with a higher rate of anastomotic stricture.


Assuntos
Neoplasias Colorretais , Diverticulite , Masculino , Humanos , Feminino , Constrição Patológica/etiologia , Constrição Patológica/epidemiologia , Ileostomia/efeitos adversos , Estudos Retrospectivos , Anastomose Cirúrgica/efeitos adversos , Fatores de Risco , Diverticulite/complicações , Fístula Anastomótica/etiologia , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia
11.
Int J Mol Sci ; 25(1)2023 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-38203598

RESUMO

Potassium (K) channels show the highest variability and most frequent alterations in expression in many tumor types, and modulation of K+ channels may represent a new window for cancer therapy. In previous work, we found that a terahertz (THz) field incident along the z-axis with a frequency of 51.87 THz increased the ion flux through K+ channels. In practice, it is difficult to ensure that the incident electromagnetic (EM) wave is strictly parallel to the direction of channel ion flow. In this paper, we found by changing the direction of the applied electric field that the EM wave of a specific frequency has the largest ion flux when the incident direction is along the ion flow, and the smallest ion flux when the incident direction is perpendicular to the ion flow, and that overall the EM wave of this frequency enhances the ion flow of the K+ channel. Changes in the direction of the applied field at a specific frequency affect the stability of the φ dihedral angle of the GLY77 residue and alter the ion permeation mechanism in the selectivity filter (SF) region, thus affecting the ion flux. Therefore, this frequency can be used to modulate K+ fluxes by THz waves to cause rapid apoptosis in potassium-overloaded tumor cells. This approach consequently represents an important tool for the treatment of cancer and is expected to be applied in practical therapy.


Assuntos
Apoptose , Eletricidade , Potássio
12.
EMBO Mol Med ; 14(12): e16501, 2022 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-36321563

RESUMO

Total fertilization failure (TFF) is an important cause of infertility; however, the genetic basis of TFF caused by male factors remains to be clarified. In this study, whole-exome sequencing was firstly used to screen for genetic causes of TFF after intracytoplasmic sperm injection (ICSI), and homozygous variants in the novel gene IQ motif-containing N (IQCN) were identified in two affected individuals with abnormal acrosome structures. Then, Iqcn-knockout mice were generated by CRISPR-Cas9 technology and showed that the knockout male mice resembled the human phenotypes. Additionally, we found that IQCN regulates microtubule nucleation during manchette assembly via calmodulin and related calmodulin-binding proteins, which resulted in head deformity with aberrant oocyte activation factor PLCζ. Fortunately, ICSI with assisted oocyte activation can overcome IQCN-associate TFF and male infertility. Thus, our study firstly identified the function of IQCN, highlights the relationship between the manchette assembly and fertilization, and provides a genetic marker and a therapeutic option for male-source TFF.


Assuntos
Infertilidade Masculina , Sêmen , Animais , Camundongos , Masculino , Humanos , Infertilidade Masculina/genética
13.
Front Plant Sci ; 13: 1036254, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36420018

RESUMO

The homeodomain-leucine zipper protein HAT belongs to the homeodomain leucine zipper subfamily (HD-Zip) and is important for regulating plant growth and development and stress tolerance. To investigate the role of HAT5 in tolerance to drought, salt, and low temperature stress, we selected a HAT gene from Pyrus sinkiangensis Yü (Pyrus sinkiangensis T.T. Yu). The sequences were analyzed using ioinformatics, and the overexpressed tomato lines were obtained using molecular biology techniques. The phenotypes, physiological, and biochemical indexes of the wild-type and transgenic tomato lines were observed under different stress conditions. We found that the gene had the highest homology with PbrHAT5. Under drought and NaCl stress, osmotic regulatory substances (especially proline) were significantly accumulated, and antioxidant enzyme activities were enhanced. The malondialdehyde level and relative electrical conductivity of transgenic tomatoes under low temperature (freezing) stress were significantly higher than those of wild-type tomatoes. The reactive oxygen species scavenging system was unbalanced. This study found that PsHAT5 improved the tolerance of tomatoes to drought and salt stress by regulating proline metabolism and oxidative stress ability, reducing the production of reactive oxygen species, and maintaining normal cell metabolism. In conclusion, the PsHAT5 transcription factor has great potential in crop resistance breeding, which lays a theoretical foundation for future excavation of effective resistance genes of the HD-Zip family and experimental field studies.

14.
J Acoust Soc Am ; 151(3): 1449, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35364921

RESUMO

In this work, solitary wave solutions of particle mechanical metamaterials are studied, in which the mass-in-mass structure with local resonators is considered. The Hertzian contact theory is used to describe adjacent particles in a precompressed granular chain. The governing wave equations are decoupled, and the expressions of bright, dark, and peaked solitary waves are derived, respectively. According to the results, both the wave velocity and prestress can affect the propagation of solitary waves. The amplitudes of bright and peaked solitary waves are smaller when a larger prestress is applied, which are different from the dark solitons. Furthermore, the wave widths become larger as the prestress increases.

15.
Int J Mol Sci ; 24(1)2022 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-36613998

RESUMO

Ion transport molecules are involved in many physiological and pathological processes and are considered potential targets for cancer treatment. In the large family of ion transport molecules, potassium (K) ion channels, as surface-expressed proteins, show the highest variability and most frequent expression changes in many tumor types. The key to exploring the permeation of K+ through potassium channels lies in the conserved sequence TVGYG, which is common in the selectivity filter (SF) region of all potassium channels. We found that the K+ flux significantly increased with the help of a specific frequency terahertz electromagnetic wave (51.87 THz) in the KcsA channel using a molecular dynamics combined model through the combined simulation of the constant electric field method and ion imbalance method. This frequency has the strongest absorption peak in the infrared spectrum of -C=O groups in the SF region. With the applied electric field of 51.87 THz, the Y78 residue at the S1 site of the SF has a smaller vibration amplitude and a more stable structure, which enables the K+ to bind closely with the carbonyl oxygen atoms in the SF and realize ion conduction in a more efficient direct Coulomb knock-on.


Assuntos
Simulação de Dinâmica Molecular , Canais de Potássio , Canais de Potássio/metabolismo , Potássio/metabolismo , Proteínas de Bactérias/metabolismo
16.
Nanomaterials (Basel) ; 11(11)2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34835542

RESUMO

Metal-supported catalyst with high activity and relatively simple preparation method is given priority to industrial production. In this work, this study reported an easily accessible synthesis strategy to prepare Mott-Schottky-type N-doped carbon encapsulated metallic Co (Co@Np+gC) catalyst by high-temperature pyrolysis method in which carbon nitride (g-C3N4) and dopamine were used as support and nitrogen source. The prepared Co@Np+gC presented a Mott-Schottky effect; that is, a strong electronic interaction of metallic Co and N-doped carbon shell was constructed to lead to the generation of Mott-Schottky contact. The metallic Co, due to high work function as compared to that of N-doped carbon, transferred electrons to the N-doped outer shell, forming a new contact interface. In this interface area, the positive and negative charges were redistributed, and the catalytic hydrogenation mainly occurred in the area of active charges. The Co@Np+gC catalyst showed excellent catalytic activity in the hydrogenation of phenylacetylene to styrene, and the selectivity of styrene reached 82.4%, much higher than those of reference catalysts. The reason for the promoted semi-hydrogenation of phenylacetylene was attributed to the electron transfer of metallic Co, as it was caused by N doping on carbon.

17.
J Acoust Soc Am ; 150(2): 891, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34470290

RESUMO

In this investigation, the bandgaps and nonreciprocal transmission of the nonlinear piezoelectric phononic crystal and elastic wave metamaterial are studied. Analytical solutions for the wave motion equations with the electro-mechanical coupling are obtained. According to the continuous conditions, the stop bands and transmission coefficients of both fundamental wave and second harmonic are derived by the stiffness matrix method. Some particular examples are presented to show the nonreciprocal transmission of the nonlinear elastic waves. Additionally, nonlinear ultrasonic experiments are applied to verify the theoretical analyses and numerical simulations. This work is intended to be helpful in the design and fabrication of devices of the elastic wave diode with piezoelectric materials.

18.
Proc Math Phys Eng Sci ; 477(2245): 20200357, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33642923

RESUMO

In this investigation, the non-reciprocal transmission in a nonlinear elastic metamaterial with imperfect interfaces is studied. Based on the Bloch theorem and stiffness matrix method, the band gaps and transmission coefficients with imperfect interfaces are obtained for the fundamental and double frequency cases. The interfacial influences on the transmission behaviour are discussed for both the nonlinear phononic crystal and elastic metamaterial. Numerical results for the imperfect interface structure are compared with those for the perfect one. Furthermore, experiments are performed to support the theoretical analysis. The present research is expected to be helpful to design tunable devices with the non-reciprocal transmission and diode behaviour of the elastic metamaterial.

19.
J Acoust Soc Am ; 150(6): 4343, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34972279

RESUMO

Cloaking invisibility is a novel technique that prevents the object from being detected in the background field. The development of new artificial materials and structures promotes the emergence of new achievements in cloaking research. In this work, a broadband square cloaking configuration of elastic wave metamaterial plate is designed and fabricated by the external active control system. The approximate parameters of the flexural wave cloak can be obtained by the coordinate transformation and achieved by alternating layers of the Acrylonitrile Butadiene Styrene (ABS), polydimethylsiloxane (PDMS), and piezoelectric (PZT) patches. With the introduction of active control systems, the square cloak has a wide effective frequency range. The simulation and experimental results show that the square cloak of flexural waves exhibits a good invisible performance in the frequency region of 500-2200 Hz. Compared to the structure without active control systems, the frequency region 2200-2750 Hz is extended for the active cloak. The design and fabrication of the broadband cloak is wished to be helpful during the practical engineering.

20.
Am J Gastroenterol ; 116(Suppl 1): S3, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37461931

RESUMO

BACKGROUND: The prevalence of cannabis use has been increasing in the United States in recent years. We examined the prevalence and predictors of cannabis use disorder among IBD hospitalizations and its effect on length of stay. METHODS: Using the 2017 National Inpatient Sample, cannabis use disorder was identified using ICD-10-CM code F12.xxx in adult IBD patients. Other variables of interest included age, sex, race, Crohn's disease (vs. ulcerative colitis), region, metropolitan status, zip code household income, primary insurance, and length of stay. Multivariate logistic and Poisson regressions were used in statistical analysis. RESULTS: Of the 17,857 IBD hospitalizations, 565 (3.1%) had cannabis use disorder. Patients with cannabis use disorder were younger (mean ± standard deviation [years]: 35.1 ± 11.8 vs. 45.6 ± 18.1), less likely female (32.7% vs. 54.1%), more likely African American (24.8% vs. 13.9%), and more likely Crohn's disease (72.0% vs. 62.2%) (all p < 0.001). There were also significant differences by region, income, and insurance. Multivariate logistic regression confirmed age (odds ratio [95% confidence interval]: 0.964 [0.957, 0.971]), female (0.444 [0.369, 0.531]), African American (1.405 [1.124, 1.750]), and Crohn's disease (1.363 [1.126, 1.657]) as predictors of cannabis use disorder. There was no association between cannabis use disorder and length of stay, confirmed in multivariate Poisson regression. CONCLUSION: Young age, male sex, African American race, and Crohn's disease were positively associated with cannabis use disorder in IBD hospitalizations. There was no effect of cannabis use disorder on length of stay.

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