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With the exponential growth in data density and user ends of wireless networks, fronthaul is tasked with supporting aggregate bandwidths exceeding thousands of gigahertz while accommodating high-order modulation formats. However, it must address the bandwidth and noise limitations imposed by optical links and devices in a cost-efficient manner. Here we demonstrate a high-fidelity fronthaul system enabled by self-homodyne digital-analog radio-over-fiber superchannels, using a broadband electro-optic comb and uncoupled multicore fiber. This self-homodyne superchannel architecture not only offers capacity boosting but also supports carrier-recovery-free reception. Our approach achieves a record-breaking 15,000 GHz aggregated wireless bandwidth, corresponding to a 0.879 Pb/s common public radio interface (CPRI) equivalent data rate. Higher-order formats up to 1,048,576 quadrature-amplitude-modulated (QAM) are showcased at a 100 Tb/s class data rate. Furthermore, we employ a packaged on-chip electro-optic comb as the sole optical source to reduce the cost, supporting a data rate of 100.5 Tb/s with the 1024-QAM format. These demonstrations propel fronthaul into the era of Pb/s-level capacity and exhibit the promising potential of integrated-photonics implementation, pushing the boundaries to new heights in terms of capacity, fidelity, and cost.
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Gelatin is a product obtained through partial hydrolysis and thermal denaturation of collagen, belonging to natural biopeptides. With irreplaceable biological functions in the field of biomedical science and tissue engineering, it has been widely applied. The amino acid sequence of recombinant human-like gelatin was constructed through a newly designed hexamer composed of six protein monomer sequences in series, with the minimum repeating unit being the characteristic Gly-X-Y sequence found in type III human collagen α1 chain. The nucleotide sequence was subsequently inserted into the genome of Pichia pastoris to enable soluble secretion expression of recombinant gelatin. At the shake flask fermentation level, the yield of recombinant gelatin is up to 0.057 g/L, and its purity can rise up to 95% through affinity purification. It was confirmed in the molecular weight determination and amino acid analysis that the amino acid composition of the obtained recombinant gelatin is identical to that of the theoretically designed. Furthermore, scanning electron microscopy revealed that the freeze-dried recombinant gelatin hydrogel exhibited a porous structure. After culturing cells continuously within these gelatin microspheres for two days followed by fluorescence staining and observation through confocal laser scanning microscopy, it was observed that cells clustered together within the gelatin matrix, exhibiting three-dimensional growth characteristics while maintaining good viability. This research presents promising prospects for developing recombinant gelatin as a biomedical material.
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We have previously reported that the expression of miR-34c-5p was up-regulated during acupuncture treatment in the setting of a cerebral ischemia/reperfusion injury (CIRI), indicating that miR-34c-5p plays an important role in healing from a CIRI-induced brain injury. This study sought to evaluate the effects of acupuncture on miR-34c-5p expression and autophagy in the forward and reverse directions using a rat focal cerebral ischemia/reperfusion model. After 120â¯minutes of middle cerebral artery occlusion and reperfusion, rats were treated with acupuncture at the "Dazhui" (DU20), "Baihui" (DU26) and "Renzhong" (DU14) points. Neurologic function deficit score, cerebral infarct area ratio, neuronal apoptosis and miR-34c-5p expression were evaluated 72â¯hr after treatment. The autophagy agonist RAPA and the antagonist 3MA were used to evaluate the neuro protective effects of autophagy-mediated acupuncture. We found that acupuncture treatment improved autophagy in the brain tissue of CIRI rats. Acupuncture reversed the negative effects of 3MA on CIRI, and acupuncture combined with RAPA further enhanced autophagy. We also found that acupuncture could increase miR-34c-5p expression in hippocampal neurons after ischemia/reperfusion. Acupuncture and a miR-34c agomir were able to enhance autophagy, improve neurologic deficits, and reduce the cerebral infarct area ratio and apoptosis rate by promoting the expression of miR-34c-5p. Silencing miR-34c resulted in a significantly reduced activating effect of acupuncture on autophagy and increased apoptosis, neurologic deficit symptoms, and cerebral infarct area ratio. This confirms that acupuncture can upregulate miR-34c-5p expression, which is beneficial in the treatment of CIRI.
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Terapia por Acupuntura , Autofagia , Isquemia Encefálica , MicroRNAs , Ratos Sprague-Dawley , Traumatismo por Reperfusão , Animais , MicroRNAs/metabolismo , MicroRNAs/genética , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/terapia , Autofagia/fisiologia , Masculino , Terapia por Acupuntura/métodos , Ratos , Isquemia Encefálica/metabolismo , Isquemia Encefálica/terapia , Infarto da Artéria Cerebral Média/terapia , Infarto da Artéria Cerebral Média/metabolismo , Apoptose/fisiologia , Neurônios/metabolismo , Modelos Animais de Doenças , Encéfalo/metabolismoRESUMO
Using dielectric deflective metasurfaces, we propose a novel, to the best of our knowledge, out-of-plane modulation scheme to realize vertical coupling on a 220â nm silicon-on-insulator platform. The metasurface is used to deflect vertical incident light to an oblique angle with high efficiency in the cladding layer. This deflection introduces a lateral wave vector component, thus preventing bi-directional transmission of traditional vertical coupling due to the second-order Bragg reflection of the grating. Additionally, an apodized design is employed for the subwavelength grating to improve mode matching with a deflection angle incident. The integration of the metasurface and subwavelength grating enables a new vertical coupling scheme with high efficiency. After global optimization, we achieved a simulation coupling efficiency of -2.19â dB. The measured coupling efficiency is -3.36â dB with a center wavelength of 1545.6â nm and a 1-dB bandwidth of 32â nm. The results confirm the feasibility of the proposed new architecture.
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As the optical communication industry advances, metropolitan area networks (MANs) and radio access networks (RANs) are extensively deployed on a large scale, demanding energy-efficient integrated light sources and simplified digital signal processing (DSP) technologies. The emergence of thin-film lithium niobate (TFLN) has given rise to high-performance, energy-efficient on-chip modulators, making on-chip optical frequency comb (OFC) more appealing. Owing to the phase uniformity and stability of this chip-scale device, it has been possible to eliminate the carrier frequency phase estimation (CPE) in DSP stacks using comb-clone-enabled self-homodyne detection. Here we report the first use, to our knowledge, of a TFLN on-chip electro-optic (EO) frequency comb to realize comb cloning and self-homodyne coherent detection. We transmit three optical pilot tones and eight data channels encoded with 20 Gbaud polarization-multiplexed 16-ary quadrature amplitude modulation (PM-16-QAM) over 10 km and 80 km standard single-mode fibers. The bit error ratios (BERs) of the eight channels reach below 10-3, a result made possible by our on-chip comb. The scalability and mass producibility of on-chip EO combs, combined with the simplified DSP, show potential in our proposed fifth-generation (5G) RAN and MAN transmission scheme.
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Neuroinflammation is a key factor in cognitive dysfunction and neurodegenerative diseases such as Alzheimer's disease (AD), so inhibiting neuroinflammation is considered as a potential treatment for AD. Epigallocatechin-3-gallate (EGCG), a polyhydroxyphenol of green tea, has been found to exhibit anti-oxidative, anti-inflammatory and neuroprotective effects. The aim of this study was to investigate the inhibitory effect of EGCG on inflammation and its mechanism. In this study, BV2 cells were simultaneously exposed to lipopolysaccharides (LPS) and the amyloid-ß oligomer (AßO) to induce inflammatory microenvironments. Inflammatory cytokines and NLRP3 inflammasome-related molecules were detected by RT-PCR and Western Blot. The results show that EGCG inhibits LPS/AßO-induced inflammation in BV2 cells through regulating IL-1ß, IL-6, and TNF-α. Meanwhile, EGCG reduces the activation of the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome and levels of intracellular ROS in BV2 cells treated with LPS/AßO by affecting the mitochondrial membrane potential (MMP). Further research found that EGCG inhibited MMP through regulating thioredoxin-interacting protein (TXNIP) in LPS/AßO-induced neuroinflammation. In conclusion, EGCG may alleviate LPS/AßO-induced microglial neuroinflammation by suppressing the ROS/ TXNIP/ NLRP3 pathway. It may provide a potential mechanism underlying the anti-inflammatory properties of EGCG for alleviating AD.
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Peptídeos beta-Amiloides , Proteínas de Transporte , Catequina , Lipopolissacarídeos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Doenças Neuroinflamatórias , Espécies Reativas de Oxigênio , Transdução de Sinais , Catequina/análogos & derivados , Catequina/farmacologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Lipopolissacarídeos/toxicidade , Animais , Peptídeos beta-Amiloides/toxicidade , Camundongos , Espécies Reativas de Oxigênio/metabolismo , Proteínas de Transporte/metabolismo , Transdução de Sinais/efeitos dos fármacos , Doenças Neuroinflamatórias/tratamento farmacológico , Doenças Neuroinflamatórias/metabolismo , Linhagem Celular , Tiorredoxinas/metabolismo , Microglia/efeitos dos fármacos , Microglia/metabolismoRESUMO
In this study, we demonstrate DAC-less PAM-4 signal generation by driving a silicon MZI modulator based on a series push-pull configuration with two independent binary signals of varying amplitudes. Such configuration boosts transfer speed between PAM4 levels, leading to enhanced performance metrics compared to the differential driving scheme. Experimentally, our scheme demonstrated a lower bit-error rate compared to the differential scheme, proving its cost-efficiency and feasibility for PAM4 generation.
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We demonstrated a low-loss O-band grating coupler on an x-cut thin-film lithium niobate substrate by implementing subwavelength and apodized structures. The subwavelength gratings were used to mitigate the refractive index discontinuity between the input taper and grating region, which was the first application of such a structure for grating coupler optimization on a thin-film lithium niobate substrate. The coupling efficiency was measured to be -1.99â dB/coupler at a wavelength of 1312.8â nm, which was the lowest loss among the reported lithium niobate grating couplers that do not use metal mirrors. The proposed design does not require metal mirrors or any additional material layers and can be easily fabricated with a single-step lithography and etching processes.
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OBJECTIVES: To explore the mechanisms of acupuncture against cerebral ischemia/reperfusion injury (CIRI) through observing the expression of circular RNA HDAC2 (circHDAC2) in the hippocampus of rats. METHODS: SD rats were randomly divided into sham-operation, model and acupuncture groups, with 13 rats in each group. The rat model of CIRI was established by middle cerebral artery occlusion. In the acupuncture group, acupuncture was delivvered at "Dazhui" (GV14), "Shuigou" (GV26) and "Baihui" (GV20), and the needles were retained for 30 min each time and acupuncture was conducted once every 12 h for a total of 7 sessions. Before and after intervention, using modified Garcia scale, the neurological function of the rats were evaluated, and TTC staining was employed to determine the cerebral infarct area. Gene chip technology was used to screen the circRNAs with differential expressions in the ischemic hippocampus, and the circRNAs with co-differential expression (co-DE circRNAs) in the model group/sham-operation group, and the acupuncture group/model group separately. Among those circRNAs, the core circRNAs were screened according to P value, fold change (FC) and gene ontology (GO) analysisï¼and their expressions in the ischemic hippocampus were determined using quantitative real-time PCR (qPCR). Based on the verification results, a competing endogenous RNA (ceRNA) prediction network was constructed. The expression levels of microRNA (miRNA) and mRNA with high node centrality in the prediction network were validated by qPCR. RESULTS: Before intervention, compared with the sham-operation group, the modified Garcia score of each modeling group decreased (P<0.01). After intervention, the modified Garcia score was reduced and the cerebral infarct area ratio increased (P<0.01) in the model group when compared with the sham-operation group. In the acupuncture group, the modified Garcia score was higher and the cerebral infarct area ratio lower (P<0.01) than those of the model group. The microarray results of gene chip showed that 16 co-DE circRNAs were down-regulated in the model group and up-regulated in the acupuncture group, and 7 co-DE circRNAs up-regulated in the model group and down-regulated in the acupuncture group. The core circHDAC2 and circNTRK2 were screened according to P value, FC and the enrichment number of GO entries. QPCR results showed that, compared with the sham-operation group, the expression of circHDAC2 and circNTRK2 of the ischemic hippocampal tissue was down-regulated in the model group (P<0.01)ï¼and that of circHDAC2 and circNTRK2 up-regulated in the acupuncture group when compared with the model group (P<0.01). The relevant ceRNA regulatory network was constructed for circHDAC2 and the prediction results showed that the regulatory networks contained 12 miRNAs and 31 mRNAs. Results of verifying miRNA with high network node centrality and mRNA relevant with nerve regulation showed that, when compared with the sham-operation group, the expression levels of miR-29a, miR-29b and the solute carrier family 30 member 3 (SLC30A3) mRNA in the ischemic hippocampus were down-regulated (P<0.01)ï¼and those of miR-3065 and mercaptopyruvate sulfurtransferase (MPST) up-regulated (P<0.01) in the model group. Compared with the model group, the expressions of miR-29a, miR-29b and SLC30A3 mRNA in the ischemic hippocampus were up-regulated (P<0.01, P<0.05), while that of miR-3065 down-regulated (P<0.05) in the acupuncture group. CONCLUSIONS: Acupuncture significantly improves the neurological function and reduces the cerebral infarct area in CIRI rats, which may be related to the regulation of hippocampal circHDAC2/miR-3065/SLC30A3 axis.
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Terapia por Acupuntura , Isquemia Encefálica , MicroRNAs , Traumatismo por Reperfusão , Ratos , Animais , RNA Circular/genética , Ratos Sprague-Dawley , Isquemia Encefálica/genética , Isquemia Encefálica/terapia , Hipocampo/metabolismo , Infarto da Artéria Cerebral Média/metabolismo , MicroRNAs/genética , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/terapia , RNA MensageiroRESUMO
Polarization dependence is an inherent challenge for wavelength-division multiplexing transceivers on silicon photonic platforms, causing severe problems with polarization-dependent losses and hindering the implementation of monolithic integrated receivers. In this study, we developed a polarization-insensitive demultiplexer on a silicon nitride (Si3N4) platform, which provides a promising solution to the polarization challenge. Comprising an etched diffraction grating (EDG) and a polarization beam splitter (PBS), the demultiplexer can achieve polarization insensitivity by introducing an additional optical path difference for polarization compensation. The fabricated demultiplexers were experimentally measured to have minimum insertion losses of 1.5â dB, cross talks of better than -25â dB, and polarization-dependent losses of better than 0.7â dB. This is the first, to the best of our knowledge, proposed solution for a polarization-insensitive EDG demultiplexer combined with a PBS on a Si3N4 platform.
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The establishment and operation of a formal recycling system for waste electrical and electronic equipment is an important measure to reduce environmental hazards and improve the recycling of resources, but how to incorporate self-employed maintainers into the system has formed an important research gap. Based on the perspective of extended producer responsibility, we argue that self-employed maintainers are required to assume the corresponding environmental responsibility for the environmental externality caused by informal maintenance activities. Using qualitative structural analysis techniques of system dynamics approach with quantitative simulation analysis techniques, we construct an incentive model for self-employed maintainers' participation in formal recycling system, based on which we propose four incentive strategies. A simulation analysis is further conducted by using the case of waste mobile phones recycling in Qingdao to verify the effectiveness of our incentive model and strategies.
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Telefone Celular , Resíduo Eletrônico , Gerenciamento de Resíduos , Gerenciamento de Resíduos/métodos , Resíduo Eletrônico/análise , Eletrônica , Reciclagem/métodosRESUMO
This paper presents a monolithic spectrometer based on a plano-convex glass lens and achieves a resolution better than 0.7â nm in the spectral range of 550-720â nm. In the monolithic instrument, all components were fixed in the machined lens, resulting in a much smaller size and more stable assembly than traditional mini spectrometers. Additionally, a dual-band design was proposed and demonstrated to extend the spectral range from the visible band (550-700â nm) to the near-infrared band (800-900â nm), thus allowing more characteristic spectral fingerprints for improved material identification. The feasibility of compensating the residual aberrations caused by structural limitations with a specifically designed aberration-correcting grating is further detailed.
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We propose and experimentally demonstrate a highly parallel photonic acceleration processor based on a wavelength division multiplexing (WDM) system and a non-coherent Mach-Zehnder interferometer (MZI) array for matrix-matrix multiplication. The dimensional expansion is achieved by WDM devices, which play a crucial role in realizing matrix-matrix multiplication together with the broadband characteristics of an MZI. We implemented a 2 × 2 arbitrary nonnegative valued matrix using a reconfigurable 8 × 8 MZI array structure. Through experimentation, we verified that this structure could achieve 90.5% inference accuracy in a classification task for the Modified National Institute of Standards and Technology (MNIST) handwritten dataset. This provides a new effective solution for large-scale integrated optical computing systems based on convolution acceleration processors.
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Dispositivos Ópticos , Aceleração , FótonsRESUMO
We demonstrated a SiN-SiN-Si three-layer silicon waveguide crossing with low-loss crossings and interlayer couplers. The underpass and overpass crossings exhibited ultralow loss (<0.82/1.16 mdB) and cross talk (<-56/-48â dB) in the wavelength range of 1260-1340â nm. To reduce the loss and length of the interlayer coupler, a parabolic interlayer coupling structure was adopted. The measured interlayer coupling loss was less than 0.11â dB from 1260 to 1340â nm, which is, to the best of our knowledge, the lowest loss reported for an interlayer coupler based on a SiN-SiN-Si three-layer platform. The total interlayer coupler length was only 120â µm.
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Frequency-modulated continuous wave (FMCW) light detection and ranging (lidar) is a promising solution for three-dimensional (3D) imaging and autonomous driving. This technique maps range and velocity measurement to frequency counting via coherent detection. Compared with single-channel FMCW lidar, multi-channel FMCW lidar can greatly improve the measurement rate. A chip-scale soliton micro-comb is currently used in FMCW lidar to enable multi-channel parallel ranging and significantly increase the measurement rate. However, its range resolution is limited due to the soliton comb having only a few-GHz frequency sweep bandwidth. To overcome this limitation, we propose using a cascaded modulator electro-optic (EO) frequency comb for massively parallel FMCW lidar. We demonstrate a 31-channel FMCW lidar with a bulk EO frequency comb and a 19-channel FMCW lidar using an integrated thin-film lithium niobate (TFLN) EO frequency comb. Both systems have a sweep bandwidth of up to 15 GHz for each channel, corresponding to a 1-cm range resolution. We also analyze the limiting factors of the sweep bandwidth in 3D imaging and perform 3D imaging for a specific target. The measurement rate achieved is over 12 megapixels per second, which verifies its feasibility for massively parallel ranging. Our approach has the potential to greatly benefit 3D imaging in fields where high range resolution is required, such as in criminal investigation and precision machining.
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Photonic radio frequency (RF) switches are promising to replace conventional electronic RF switches in modern RF communication systems owing to their high switching speed and immunity to electromagnetic interference. However, existing photonic RF switches are generally based on frequency or polarization filtering. Thus, they require more light sources and filters to increase the number of switching channels, consequently limiting scalability. We propose a silicon-integrated photonic RF switch based on optical switching. RF signals are first modulated into the optical domain and switched through phase control of the phase shifters in the optical switch. Switching is not related to the frequency or polarization of the optical carriers, thus reducing the number of light sources required. Experimental results demonstrate 10-GHz switching of two RF signals with frequencies of 20â GHz and 30â GHz. The proposed photonic RF switch can be further expanded to form a large switch matrix, possibly contributing to the development of large-scale RF communication systems.
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Here, a high-linearity dual-drive scheme using a single silicon dual-drive Mach-Zehnder modulator is presented. The bias voltages and RF amplitudes of the two driving arms are adjusted such that the nonlinearity of the transfer function of the Mach-Zehnder interferometer cancels out the nonlinear response of the arms. Using the proposed scheme, the spurious-free dynamic range of the third-order intermodulation distortion is 123.4â dBâ Hz6/7, which is believed to be a record-breaking value for silicon modulators. In comparison, the result obtained using a conventional single-drive scheme is 102.6â dB·Hz2/3. The proposed scheme could simplify the design of modulators and promote high-performance microwave photonic links.
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We demonstrate a low-loss, high-efficiency lithium niobate electro-optic (EO) modulator with optical isolation trenches to achieve stronger field confinement and reduced light absorption loss. The proposed modulator realized considerable improvements, including a low half-wave voltage-length product of 1.2â V·cm, an excess loss of â¼2.4â dB, and a broad 3-dB EO bandwidth of over 40â GHz. We developed a lithium niobate modulator with, to the best of our knowledge, the highest reported modulation efficiency of any Mach-Zehnder interferometer (MZI) modulator.
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OBJECTIVE: To observe the effects of acupuncture on the expression of type â ¢ phosphatidylinositol 3-hydroxykinase (PI3K) and Beclin-1 in hippocampus of rats with cerebral ischemia/reperfusion injury (CI/RI), so as to explore the mechanism of acupuncture in regulating type â ¢ PI3K pathway to activate autophagy in the hippocampal neurons of CI/RI rats. METHODS: SD rats were randomly divided into sham operation group (n=11) and operation group. Then after successful modeling, rats in the operation group were randomly divided into model, acupuncture, model+3-MA and acupuncture+3-MA groups, with 11 rats in each group. The model of CI/RI was established by occlusion of the middle cerebral artery. Rats in the model+3-MA and acupuncture+3-MA groups were injected with 3-MA (400 nmol/ 5 µL) 5 µL into the lateral ventricle 30 min before reperfusion. Rats in the acupuncture and acupuncture+3-MA groups were punctured with filiform needles at "Dazhui" (GV14), "Shuigou" (GV26) and "Baihui" (GV20) and stimulated manually once every 15 min. The acupuncture intervention was conducted for 30 min each time, once every 12 h for a total of 7 times. The degree of neurological impairment was evaluated 2 h after reperfusion and after intervention by Garcia score. After intervention, the percentage of cerebral ischemic area was observed by TTC staining, the protein expression levels of type â ¢ PI3K, Beclin-1, microtubule-associated protein 1 light chain 3B (LC3B), lysosome associated membrane protein 2 (Lamp2) and P62 in ischemic hippocampal tissue were detected by Western blot, the ultrastructure of neurons in ischemic hippocampus was observed by transmission electron microscopy (TEM). RESULTS: Compared with the sham operation group, the Garcia score was decreased (P<0.01), the percentage of cerebral ischemic area was increased (P<0.01), the expression levels of type â ¢ PI3K, Beclin-1, LC3B-â ¡/â , Lamp2 proteins were decreased (P<0.01), and the expression level of P62 protein was increased (P<0.01) in ischemic hippocampal tissue in the model group. Compared with the model group, the Garcia score was increased (P<0.01), the percentage of cerebral ischemic area was decreased (P<0.01), the expression levels of type â ¢ PI3K, Beclin-1, LC3B-â ¡/â , Lamp2 proteins were increased (P<0.01, P<0.05) and the expression level of P62 was decreased (P<0.01) in ischemic hippocampal tissue in the acupuncture groupï¼ the percentage of cerebral ischemic area was increased (P<0.05), the expressions of type â ¢ PI3K and Beclin-1 were decreased (P<0.01) and the expression level of P62 protein was increased (P<0.05) in ischemic hippocampal tissue in the mo-del+3-MA group. Compared with the model +3-MA group, the Garcia score was increased (P<0.05), the percentage of cerebral ischemic area was decreased (P<0.01), the expression levels of type â ¢ PI3K, Beclin-1, LC3B-â ¡/â in ischemic hippo-campal tissue were increased (P<0.01, P<0.05) in the acupuncture+3-MA group. Compared with the acupuncture group, the Garcia score was decreased, the percentage of cerebral ischemic area was increased (P<0.05, P<0.01), the expression levels of type â ¢ PI3K, Beclin-1, Lamp2 proteins were decreased (P<0.01, P<0.05) and P62 protein was increased (P<0.05) in ischemic hippocampal tissue in the acupuncture+3-MA group. The results of TEM showed that the edema of neurons was heavier, and few hypolysosomes existed in the model group; there was no obvious damage to neuronal structure, intracellular matrix was abundant, and a few lysosomes existed in the acupuncture group; the neuronal cells had mild edema and primary lysosomes were present in the acupuncture +3-MA group. CONCLUSION: Acupuncture can improve the symptoms of neurological impairment and reduce the percentage of cerebral ischemic area in rats with CI/RI. The mechanism may be related to regulating type â ¢ PI3K/Beclin-1 pathway, up-regulating the expressions of autophagy related factors LC3B-â ¡ and Lamp2, and down-regulating the expression of P62.
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Terapia por Acupuntura , Isquemia Encefálica , Traumatismo por Reperfusão , Ratos , Animais , Ratos Sprague-Dawley , Proteína Beclina-1/genética , Fosfatidilinositol 3-Quinases/genética , Isquemia Encefálica/genética , Isquemia Encefálica/terapia , Infarto Cerebral , Hipocampo , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/terapia , Neurônios , Autofagia/genética , ReperfusãoRESUMO
Fabrication errors inevitably occur in device manufacturing owing to the limited processing accuracy of commercial silicon photonic processes. For silicon photonic devices, which are mostly processing-sensitive, their performances usually deteriorate significantly. This remains an unsolved issue for mass production, particularly for passive devices, because they cannot be adjusted once fixed in processes. This study presents a post-processing trimming method to compensate for fabrication errors by changing the cladding equivalent refractive indices of devices with femtosecond lasers. The experimental results show that the resonant wavelengths of micro-ring resonators can be regularly shifted within their free spectral range via tuning the illuminating area, focusing position, emitting power, and scanning speed of the trimming femtosecond laser with an acceptable loss increase. These experiments, as well as the trimming experiments in improving the phase balance of Mach-Zehnder interferometer switches, indicate that the femtosecond laser trimming method is an effective and fast method for silicon photonic devices.