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1.
PLoS Comput Biol ; 19(12): e1011704, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38150484

RESUMO

An influential account of neuronal responses in primary visual cortex is the normalized energy model. This model is often implemented as a multi-stage computation. The first stage is linear filtering. The second stage is the extraction of contrast energy, whereby a complex cell computes the squared and summed outputs of a pair of the linear filters in quadrature phase. The third stage is normalization, in which a local population of complex cells mutually inhibit one another. Because the population includes cells tuned to a range of orientations and spatial frequencies, the result is that the responses are effectively normalized by the local stimulus contrast. Here, using evidence from human functional MRI, we show that the classical model fails to account for the relative responses to two classes of stimuli: straight, parallel, band-passed contours (gratings), and curved, band-passed contours (snakes). The snakes elicit fMRI responses that are about twice as large as the gratings, yet a traditional divisive normalization model predicts responses that are about the same. Motivated by these observations and others from the literature, we implement a divisive normalization model in which cells matched in orientation tuning ("tuned normalization") preferentially inhibit each other. We first show that this model accounts for differential responses to these two classes of stimuli. We then show that the model successfully generalizes to other band-pass textures, both in V1 and in extrastriate cortex (V2 and V3). We conclude that even in primary visual cortex, complex features of images such as the degree of heterogeneity, can have large effects on neural responses.


Assuntos
Orientação , Córtex Visual , Humanos , Orientação/fisiologia , Córtex Visual/diagnóstico por imagem , Córtex Visual/fisiologia , Neurônios/fisiologia , Imageamento por Ressonância Magnética/métodos , Estimulação Luminosa/métodos
2.
ACS Appl Mater Interfaces ; 15(40): 47509-47519, 2023 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-37769329

RESUMO

Liquid crystal elastomers (LCEs) have garnered considerable attention in the field of four-dimensional (4D) printing due to their large, reversible, and anisotropic shape-morphing capabilities. By utilizing direct ink writing, intricate LCE structures with programmable shape morphing can be achieved. However, the maintenance of the actuated state for LCEs requires continuous and substantial external stimuli, presenting challenges for practical applications, particularly under ambient conditions. This study reports a straightforward and effective physical approach to lock the actuated state of LCEs through rapid cooling while preserving their reversible performance. Rapid cooling significantly reduces the mobility of the lightly cross-linked network in LCEs, resulting in a notably slow recovery of mesogen alignment. As a result, the locked LCE structures retain their actuated state even at room temperature. Moreover, we demonstrate the ability to achieve tunable shapes between the original and actuated states by modulating the cooling rate, i.e., varying the temperature and type of cooling medium. The proposed method opens up new possibilities to achieve stable and tunable shape locking of soft devices for engineering applications.

3.
Polymers (Basel) ; 14(9)2022 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-35566921

RESUMO

Although thermosetting polyphenylene oxide- (PPO) based composites with excellent dielectric properties have been widely accepted as superior resin matrices of high-performance copper clad laminate (CCL) for 5G network devices, there has been limited information regarding the composition-process-structure-property relationships of the systems. In this work, the effects of peroxide initiator concentration on the structure and dielectric properties of a free radical cured ultralow loss PPO/Triallyl isocyanate (TAIC) composite system were studied. As expected, the glass transition temperature (Tg) and storage modulus increased with the advancing of crosslinking, whereas the dielectric loss showed an "abnormal" rise with the increase in crosslink density. Extensive studies were carried out by varying the initiator contents and characterizing the structure with spectroscopy, thermal analysis, and positron annihilation lifetime spectrum (PALS) techniques. The results show that the competition of polarity, crosslink density, free volume, and free TAIC are the key factors determining the dielectric properties of the composites.

4.
Ann Transl Med ; 9(18): 1459, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34734011

RESUMO

BACKGROUND: Using bioinformatic methods to explore the differentially expressed genes (DEGs) of human idiopathic pulmonary fibrosis (IPF) and to elucidate the pathogenesis of IPF from the genetic level. METHODS: The GSE110147 gene expression profile was downloaded from the GEO database. The data of lung adenocarcinoma (LUAD) samples, lung squamous cell carcinoma (LUSC) samples and normal samples were downloaded from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. DEGs between IPF patients and healthy donors were analyzed using the GEO2R tool. Use the "clusterprofiler" package in R software to perform gene ontology (GO) and KEGG pathway enrichment analysis, and then perform function annotation and protein-protein interaction (PPI) network construction in the STRING online tool. The Genome Browser tool of the university of california santa cruz (UCSC) online website was used to predict transcription factors (TFs) of genes. In the final, the results were analyzed synthetically. RESULTS: A total of 9,183 DEGs were identified, of which 4,545 genes were down-regulated, and 4638 were up-regulated. MMP1, SPP1, and BPIFB1 were the top three DEGs with the highest significant up-regulation. These DEGs played an important role in the occurrence of IPF through the MAPK (mitogen-activated protein kinase) signaling pathway. Furthermore, 50 DEGs were enriched in the expression of PD-L1 and the PD-1 checkpoint pathway in cancer, of which 11 genes were re-enriched in the pathway of non-small cell lung cancer. The expression of the 11 genes were extensively regulated by CTCFL, SP2 and ZNF341. Most of them were differentially expressed between lung cancers and normal lung tissues. The overall survival (OS) curve of LUAD were significantly stratified by AKT2, KRAS, PIK3R1, meanwhile the OS curve of LUAC was significantly stratified by MAPK3. CONCLUSIONS: Bioinformatics analysis revealed that DEGs including MPP1 might be potential targets and biomarkers of IPF, and the MAPK signaling pathway is related to the occurrence and development of IPF. The development of IPF lung cancer complications may be related to the activation of genes enriched in PD-L1 expression and PD-1 checkpoint pathway, which provides clues to the pathogenesis of IPF combined with lung cancer.

5.
Ann Transl Med ; 9(20): 1570, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34790776

RESUMO

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a highly fatal lung disease of unknown etiology with a median survival after diagnosis of only 2-3 years. Its poor prognosis is due to the limited therapy options available as well as the lack of effective prognostic indicators. This study aimed to construct a novel prognostic signature for IPF to assist in the personalized management of IPF patients during treatment. METHODS: Differentially-expressed genes (DEGs) in IPF patients versus healthy individuals were analyzed using the "limma" package of R software. Immune-related genes (IRGs) were obtained from the ImmPort database. Univariate Cox regression analysis was adopted to screen significantly prognostic IRGs for IPF patients. Multiple Cox regression analysis was used to identify optimal prognostic IRGs and construct a prognostic signature. RESULTS: Compared with healthy individuals, there were a total of 52 prognosis-related DEGs in the bronchoalveolar lavage (BAL) samples of IPF patients, of which 37 genes were identified as IRGs. Of these, five genes (CXCL14, SLC40A1, RNASE3, CCR3, and RORA) were significantly associated with overall survival (OS) in IPF patients, and were utilized for establishment of the prognostic signature. IPF patients were divided into high- and low-risk groups based on the prognostic signature. Marked differences in the OS probability were observed between high- and low-risk IPF patients. The area under curves (AUCs) of the receiver operating characteristic (ROC) curve for the prognostic signature in the training and validation cohorts were 0.858 and 0.837, respectively. The expression levels between RNASE3 and SLC40A1 (P<0.01, r=0.394), between RORA and CXCL14 (P<0.01, r=-0.355), between CCR3 and CXCL14 (P<0.01, r=0.258), as well as between RNASE3 and CCR3 (P<0.01, r=0.293) were significantly correlated. CONCLUSIONS: We developed a validated and reproducible IRG-based prognostic signature that should be helpful in the personalized management of patients with IPF, providing new insights into the relationship between the immune system and IPF.

6.
Polymers (Basel) ; 12(9)2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32878229

RESUMO

The recycling of macromolecular biowastes has been a problem for the agriculture industry. In this study, a novel N, S-codoped activated carbon material with an ultrahigh specific area was produced for the application of a supercapacitor electrode, using tobacco stalk biowastes as the carbon source, KOH as the activating agents and thiourea as the doping agent. Tobacco stalk is mainly composed of cellulose, but also contains many small molecules and inorganic salts. KOH activation resulted in many mesopores, giving the tobacco stem-activated carbon a large specific surface area and double-layer capacitance. The specific surface area of the samples reached up to 3733 m2·g-1, while the maximum specific capacitance of the samples obtained was up to 281.3 F·g-1 in the 3-electrode tests (1 A·g-1). The doping of N and S elements raised the specific capacitance significantly, which could be increased to a value as high as 422.5 F·g-1 at a current density of 1 A·g-1 in the 3-electrode tests, but N, S-codoping also led to instability. The results of this article prove that tobacco stalks could be efficiently reused in the field of supercapacitors.

7.
Arch Sex Behav ; 49(7): 2511-2530, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32588256

RESUMO

People often expect men and women to look, act, and think like typical members of their gender groups. When men and women deviate from gender-stereotypical expectations across various domains, people tend to denigrate them, compared to those who follow stereotypical expectations. This derogatory attitude-termed the backlash effect-has been well supported by psychological research. However, previous studies on the backlash effect have often neglected the fact that men and women can be counter-stereotypical of their gender groups, to varying degrees. This research tried to address this continuous nature of counter-stereotypical characteristics in various domains using six experiments to evaluate individual responses to gendered facial cues, behaviors, and psychological traits. We conducted three studies, with two experiments per study. Most importantly, this research proposed a threshold model of gender stereotype maintenance to explain people's evaluations of gender-counter-stereotypical targets across various domains. The threshold model suggested that appraisal for a target with balanced gender-stereotypical and gender-counter-stereotypical characteristics tends to be more positive than for a target who strictly adheres to gender stereotypes or gender-counter-stereotypical characteristics. The results of all three studies supported the threshold model, which demonstrated a curvilinear pattern of participants' appraisals and targets' gender-counter-stereotypical degrees. The threshold model of stereotype maintenance has enriched the traditional stereotype maintenance theory and enlightened the development of a more effective impression management strategy. Moreover, it provided more ecological validity that treated gender counter-stereotype as a continuum rather than a binary variable.


Assuntos
Identidade de Gênero , Comportamento Estereotipado/fisiologia , Adulto , Feminino , Humanos , Estudos Longitudinais , Masculino , Adulto Jovem
8.
Sheng Wu Gong Cheng Xue Bao ; 34(7): 1156-1168, 2018 Jul 25.
Artigo em Chinês | MEDLINE | ID: mdl-30058314

RESUMO

Trametes versicolor has strong ability to degrade environmental organic pollutants. NADPH-cytochrome P450 reductase (CPR) of T. versicolor transfers electron to cytochrome P450s (CYPs) and participates in the degradation process of organic pollutants. Sequence analysis showed that the genome of T. versicolor contains 1 potential CPR and multiple potential CYP sequences. To further study the molecular mechanism for the involvement of T. versicolor CPR in the cellular degradation of organic pollutants, a CPR gene from T. versicolor was cloned and heterologously expressed in Escherichia coli. Subsequently, the main properties of the recombinant enzyme were investigated. A truncated CPR protein lacking the predicted membrane anchor region (residues 1-24), named CPRΔ24, was overexpressed as a soluble form in E. coli. The recombinant CPRΔ24 protein showed a molecular weight consistent with the theoretical value of 78 kDa. Recombinant CPRΔ24 was purified using a Ni²âº-chelating column followed by size exclusion chromatography. The specific activity of the purified CPRΔ24 was 5.82 U/mg. The CPRΔ24 enzyme displayed the maximum activity at 35 ℃ and pH 8.0. It has different degrees of tolerance against several types of metal ions and organic solvents. The apparent Km and kcat values of recombinant CPRΔ24 for NADPH were 19.7 µmol/L and 3.31/s, respectively, and those for the substrate cytochrome c were 25.9 µmol/L and 10.2/s, respectively, under conditions of 35 ℃ and pH 8.0. The above research provides the basis for exploring the functional mechanism of T. versicolor CPR in the degradation pathway of environmental organic pollutants.


Assuntos
NADPH-Ferri-Hemoproteína Redutase/biossíntese , Trametes/enzimologia , Clonagem Molecular , Sistema Enzimático do Citocromo P-450 , Escherichia coli , Proteínas Fúngicas/biossíntese , Microbiologia Industrial , Proteínas Recombinantes/biossíntese
9.
J Struct Biol ; 196(3): 426-436, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27645700

RESUMO

Here we report the first crystal structure of a secretory α-glucoside hydrolase isolated from Pseudoalteromonas sp. K8, PspAG97A, which belongs to glycoside hydrolase family 97 and exhibits halophilic property. PspAG97A lacks an acidic surface, that is considered essential for protein stability at high salinity. Interestingly, PspAG97A unusually contains a chloride ion coordinated by the guanidinium group of Arg171 and the main chain amide groups of Tyr172 and Glu173 at the active site. The structures of PspAG97A complexed with acarbose and panose demonstrate that residues Glu173, Arg171 and Asn170 for subsite +1 decide the substrate specificity of the enzyme for the α-1,6-glucosidic linkage. Structural alterations observed in the R171K variant and enzyme kinetic experiments focusing on chloride assisted activation suggest that the active site chloride serves to properly orient Glu173, Arg171 and Asn170 to facilitate substrate recognition. Furthermore, the chloride assists the binding of Glu173 to the conserved calcium ion and plays an essential role in properly positioning the base catalyst Glu456. In sum, our results provide valuable insight into the structural basis of protein halophilicity.


Assuntos
Cristalografia por Raios X , Glicosídeo Hidrolases/química , Pseudoalteromonas/química , Acarbose/química , Sequência de Aminoácidos/genética , Sítios de Ligação , Catálise , Domínio Catalítico , Cloretos/química , Glucanos/química , Glicosídeo Hidrolases/ultraestrutura , Cinética , Mutagênese Sítio-Dirigida , Ligação Proteica , Conformação Proteica , Pseudoalteromonas/enzimologia , Especificidade por Substrato
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