We herein designed and synthesized allenyl benzoxazinones of a novel type, which were then involved in a Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition ...reaction with 1-azadienes. A broad range of chiral C2-functionalized quinoline derivatives were afforded in moderate to good yields (up to 93%) with high enantioselectivities (up to 93% ee) in this reaction.
A wideband integrated antenna is proposed with realization of radiation and dual polarized absorption in same frequency band. The novelty of the proposed integrated structure lies in the ...share-aperture of frequency-selective absorber and magnetoelectric dipole, which remain mutually independent and orthogonal operating characteristics. In the share-structure, each array element can be selectively connected to an excitation port or a resistor loading (50 Ω) to re-use the antenna port impedance for receiving and absorbing co-polarized waves. While the cross-polarized waves are reflected by antenna ground and absorbed by mounted resistors on the symmetric patches at the top layer of the antenna array. Consequently, the proposed antenna exhibits both wideband radiation and dual polarized absorption simultaneously with low profile (0.22λ0). Finally, a prototype 2×2 antenna array is fabricated and measured, demonstrating an impedance bandwidth of 92.7% for |S11| < −10 dB from 2.2 to 6 GHz. Moreover, the proposed antenna has 10 dB RCS reduction bandwidth of 100% (2-6 GHz) for x- and y-polarized normally incident waves.
A new method for frequency selective surface (FSS) with high selectivity, namely, filtenna-filtenna (FA-FA)-based technique, is proposed, which consists of two filtering antennas and impedance ...matching network. Based on the reciprocity theorem, the radiation null of filtenna can provide a stopband of the proposed FSS. In this work, it is validated by using a periodic array of back-to-back magnetoelectronic (ME)-dipole antennas with split-ring resonators (SRRs), and a slotted GND plane is used to connect the two ME-dipole antennas for impedance matching. Bandpass response of the proposed FSS is realized by the intrinsic high-pass characteristic of ME-dipole antennas and the bandstop characteristic of SRRs. Four transmission zeros (TZs) and three transmission poles (TPs) are generated, exhibiting a high-order filtering response. TZs and TPs are analyzed by equivalent circuit model and current distributions. The 3 dB fractional bandwidth (<inline-formula> <tex-math notation="LaTeX">{\mathrm {FBW}}_{\mathrm {3\,dB}} </tex-math></inline-formula>) of 38.5% in the passband and the 20 dB fractional bandwidths <inline-formula> <tex-math notation="LaTeX">({\mathrm {FBW}}_{\mathrm {20\,dB}}) </tex-math></inline-formula> of 8.7% in the lower rejection band and 13.8% in upper rejection band are obtained in this design. Finally, a prototype is fabricated and measured to further validate the proposed FA-FA-based technique. Simulated and measured results show that the proposed FA-FA-based FSS is with the distinct advantages, including wide passband, low profile, tunable TZs, and dual-polarized application, which verifies the proposed method of FSSs.
To compare the effects of exercise training under hypoxia versus normoxia on cognitive function in clinical and non-clinical populations.
From inception to June 13th, 2022, a systematic search was ...performed on PubMed, Web of Science, Embase, Scopus, and Cochrane Central Register of Controlled Trials.
Randomized controlled trials comparing the effects of exercise under hypoxic vs normoxic on cognition in clinical and non-clinical populations were included. The systematic search generated 14,894 relevant studies, of which 12 were finally included.
Two reviewers independently extracted data from included studies. Results were expressed as standardized mean difference (SMD). Each included study was assessed using the Cochrane Risk of Bias 1.0 (RoB1.0) tool. Finally, the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system was used to rate the certainty of evidence for each outcome.
Overall, 12 studies with a total of 338 participants met the inclusion criteria. The pooled results suggested that hypoxia exercise had a small but not statistically significant positive effect on overall cognitive function (SMD=0.064, 95% confidence interval (CI): -0.156-0.284, P=.567, very low-certainty evidence), when compared with normoxic exercise. Regarding the domain-specific cognitive functions, there was a medium and significant positive effect on memory (SMD=0.594, 95% CI: 0.068 to 1.120, P=.027, very low-certainty evidence), while effects on visuospatial function (SMD=0.490, 95% CI: -0.030 to 1.010, P=.065, very low-certainty evidence), attention (SMD=0.037, 95% CI: -0.340 to 0.414, P=.847, very low-certainty evidence), executive function (SMD=0.096, 95% CI: -0.268 to 0.460, P=.605, very low-certainty evidence), and processing speed (SMD=-0.145, 95% CI: -0.528 to 0.239, P=.459, very low-certainty evidence) were not statistically significant.
The current pooled results revealed that hypoxic exercise was related to improved cognitive performance. Nevertheless, exercise under hypoxia did not have a significant advantage in cognitive promotion when compared with exercise under normoxia.
Based on the theory of interhemispheric inhibition and the bimodal balance–recovery model in stroke, we explored the effects of excitation/inhibition (E/I) of parvalbumin (PV) neurons in the ...contralateral primary motor cortex (cM1) connecting the ipsilateral M1 (iM1) via the corpus callosum (cM1-CC-iM1) of ischemic stroke rats by optogenetic stimulation.
We tested this by injecting anterograde and retrograde virus in rats with middle cerebral artery occlusion (MCAO), and evaluated the neurological scores, motor behavior, volume of cerebral infarction and the E/I balance of the bilateral M1 two weeks after employing optogenetic treatment.
We found that concentrations of Glu and GABA decreased and increased, respectively, in the iM1 of MCAO rats, and that the former increased in the cM1, suggesting E/I imbalance in bilateral M1 after ischemic stroke. Interestingly, optogenetic stimulation improved M1 E/I imbalance, as illustrated by the increase of Glu in the iM1 and the decrease of GABA in both iM1 and cM1, which were accompanied by an improvement in neurological deficit and motor dysfunction. In addition, we observed a reduced infarct volume, an increase in the expression of the NMDAR and AMPAR, and a decrease in GAD67 in the iM1 after intervention.
Optogenetic modulation of PV neurons of the iM1-CC-cM1 improve E/I balance, leading to reduced neurological deficit and improved motor dysfunction following ischemic stroke in rats.
•iM1-CC-cM1 PV neurons play a key role in the IHI theory.•Optogenetic stimulation of iM1-CC-cM1 PV neurons promotes stroke rehabilitation.•Activation of iM1-CC-cM1 PV neurons improves the excitation/inhibition balance.•IHI theory better predicts stroke recovery in cases with high structural retention.
A new filtenna-to-filtenna (FA-T-FA) cross-polarization converter (CPC) is proposed using multimode resonance (MMR) techniques. The CPC unit cell comprises two identical filtennas and two matching ...vias. Each filtenna consists of a magneto-electric (ME) dipole antenna and a ground plane with four L-shaped resonators. The matching vias not only match the two filtennas but also enable a 1-bit phase resolution of the CPC. First, modes of the filtennas and the matching vias are investigated independently. Afterward, the filtennas are arranged back-to-back and orthogonal, and connected using the matching vias, forming an FA-T-FA CPC. This configuration allows linearly polarized waves to be transformed into their orthogonal counterparts upon passing through the CPC. Four transmission modes of the CPC are generated, leading to a −3 dB fractional bandwidth of 17.9%, a polarization conversion ratio (PCR) of 99%, and an energy conversion ratio (ECR) of 94% in the passband. The lower and upper rejection bands of the CPC benefit from the ME dipole antennas and the L-shaped resonators, respectively. Moreover, the proposed CPC can maintain a stable response under the incidence angle of 55°. To validate its efficacy, the FA-T-FA CPC is fabricated and measured. Simulation and measurement results demonstrate a reasonable agreement, affirming the practical viability of the proposed CPC. With its wide passband, high selectivity, high PCR and ECR, 1-bit phase resolution, and good angular stability, the FA-T-FA CPC emerges as a promising candidate for high-performance and multifunctional metasurfaces.
Alzheimer's disease (AD) is a progressive neurodegenerative disorder with clinical, biological, and pathological features occurring along a continuum from normal to end-stage disease. Currently, the ...diagnosis of AD depends on clinical assessments and post-mortem neuropathology, which is unbenefited early diagnosis and progressive monitoring. In recent years, clinical studies have reported that the level of cerebrospinal fluid (CSF) and blood neurogranin (Ng) are closely related to the occurrence and subsequent progression of AD. Therefore, the study used meta-analysis to identify the CSF and blood Ng levels for the development of diagnosis biomarker of patients with AD and mild cognitive impairment (MCI). We searched the Pubmed, Embase, Cochrane Library, and Web of Science databases. A total of 24 articles eligible for inclusion and exclusion criteria were assessed, including 4661 individuals, consisting of 1518 AD patients, 1501 MCI patients, and 1642 healthy control subjects. The level of CSF Ng significantly increased in patients with AD and MCI compared with healthy control subjects (SMD: 0.84 95% CI: 0.70-0.98, P < 0.001; SMD: 0.53 95% CI: 0.40-0.66, P = 0.008), and higher in AD patients than in MCI patients (SMD: 0.18 95% CI: 0.07-0.30, P = 0.002), and CSF Ng level of patients with MCI-AD who progressed from MCI to AD was significantly higher than that of patients with stable MCI (sMCI) (SMD: 0.71 95% CI: 0.25-1.16, P = 0.002). Moreover, the concentration of Ng in blood plasma exosomes of patients with AD and MCI was lower than that of healthy control subjects (SMD: -6.657 95% CI: -10.558 to -2.755, P = 0.001; and SMD: -3.64 95% CI: -6.50 to -0.78, P = 0.013), and which in patients with AD and MCI-AD were also lower than those in patients with sMCI (P < 0.001). Furthermore, regression analysis showed a negative relationship between MMSE scores and CSF Ng levels in MCI patients (slope = -0.249 95% CI: -0.003 to -0.495, P = 0.047). Therefore, the Ng levels increased in CSF, but decreased in blood plasma exosomes of patients with AD and MCI-AD, and highly associated with cognitive declines. These findings provide the clinical evidence that CSF and blood exosomes Ng can be used as a cognitive biomarker for AD and MCI-AD, and further studies are needed to define the specific range of Ng values for diagnosis at the different stages of AD.
BACKGROUNDAstrocytes have been demonstrated to undergo conversion into functional neurons, presenting a promising approach for stroke treatment. However, the development of small molecules capable of ...effectively inducing this cellular reprogramming remains a critical challenge.METHODSInitially, we introduced a glial cell marker gene, GFaABC1D, as the promoter within an adeno-associated virus vector overexpressing miR-124 into the motor cortex of an ischemia-reperfusion model in rats. Additionally, we administered NeuroD1 as a positive control. Lentiviral vectors overexpressing miR-124 were constructed and transfected into primary rat astrocytes. We assessed the cellular distribution of GFAP, DCX, and NeuN on days 7, 14, and 28, respectively.RESULTSIn rats with ischemic stroke, miR-124-transduced glial cells exhibited positive staining for the immature neuron marker doublecortin (DCX) and the mature neuron marker NeuN after 4 weeks. In contrast, NeuroD1-overexpressing model rats only expressed NeuN, and the positive percentage was higher in co-transfection with miR-124 and NeuroD1. Overexpression of miR-124 effectively ameliorated neurological deficits and motor functional impairment in the model rats. In primary rat astrocytes transduced with miR-124, DCX was not observed after 7 days of transfection, but it appeared at 14 days, with the percentage further increasing to 44.6% at 28 days. Simultaneously, 15.1% of miR-124-transduced cells exhibited NeuN positivity, which was not detected at 7 and 14 days. In vitro, double fluorescence assays revealed that miR-124 targeted Dll4, and in vivo experiments confirmed that miR-124 inhibited the expression of Notch1 and DLL4.CONCLUSIONSThe overexpression of miR-124 in astrocytes demonstrates significant potential for improving neurological deficits following ischemic stroke by inhibiting DLL4 expression, and it may facilitate astrocyte-to-neuronal transformation.
The metal-free DBU catalyzed 3+2 cycloaddition of 3-homoacyl coumarins with cyclic 1-azadienes proceeded smoothly to furnish the corresponding highly functionalized cyclopentane-fused coumarins with ...excellent diastereoselectivity and complete chemoselectivity and in good yields under mild conditions.
A novel filtenna-filter-filtenna (FA-F-FA)-based frequency-selective surface (FSS) technique is proposed using multiple-mode resonators (MMRs). Based on this method, a bandpass FSS with simultaneous ...wide passband and wide out-of-band rejection is validated. The MMR unit cell consists of two back-to-back magnetoelectric (ME)-dipole antennas and a filter-embedded GND plane. Four modes are analyzed and used to acquire a wide passband of the FSS. At the same time, wide out-of-band rejections in both lower and upper bands are controlled by the filter-embedded GND plane with four rotationally symmetric quarter-wavelength transmission lines (QWTLs). Moreover, the GND plane plays a crucial role in the impedance matching of the proposed FSS. As a result, four transmission poles (TPs) and three transmission zeros (TZs) of the proposed FSS can be obtained, leading to a fourth-order filtering response and wide out-of-band rejection. An equivalent circuit model, current distributions, and electric field distributions are introduced to illustrate the working mechanism of the FSS. Finally, the proposed FA-F-FA-based FSS with a 50.2% 3-dB fractional bandwidth (FBW<inline-formula> <tex-math notation="LaTeX">_{\mathrm {3 dB}} </tex-math></inline-formula>) in the passband and 53.5% and 119.2% of the 20-dB fractional bandwidth (FBW<inline-formula> <tex-math notation="LaTeX">_{\mathrm {20 dB}} </tex-math></inline-formula>), respectively, in the lower and upper rejection bands is achieved. The S-parameters are stable under an oblique incident angle of 50°. The measured and simulated results are in good agreement. In addition, the proposed FSS has the advantages of low profile, assembly free, and dual-polarization application, which verify the versatility of the FA-F-FA-based MMR FSS.
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