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1.
Plant Signal Behav ; 19(1): 2399429, 2024 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-39229864

RESUMO

Currently, applying lime to cadmium (Cd)-contaminated paddy fields to increase pH and reduce Cd availability is an effective method to control excessive Cd levels in rice grain. However, under hydroponic conditions, the impact of increased pH on Cd accumulation in different rice varieties remains unclear. This study employed three rice varieties (Yuzhenxiang, Shaoxiang 100, Xiangwanxian 12) with different Cd accumulation characteristics under different pH and long-term treatment with 1 µM CdCl2, to study the effect of pH on growth and Cd accumulation in different rice varieties. The result showed that as pH shifted from 5 to 8, the SPAD values, shoot dry weight, and plant height of the three rice varieties significantly decreased. The main root length, root volume, and root dry weight of Yuzhenxiang, and Shaoxiang100 significantly decreased. Conversely, the root architecture indicators of Xiangwanxian 12 did not change significantly. As for element accumulation, increasing the pH significantly increased the content of Mn in both the shoots and roots of all three varieties. Yuzhenxiang significantly reduced Cd content in both the shoots and roots of rice, while Shaoxiang100 significantly increased Cd content in both parts. Xiangwanxian 12 showed a significant increase in Cd content in the shoots but a decrease in the roots. In terms of subcellular distribution, Yuzhenxiang significantly reduced Cd concentrations in the cell wall and organelles of root cells, resulting in lower Cd concentrations in the root tissue. Conversely, Shaoxiang100 significantly increased Cd concentrations in the cell wall, organelles, and soluble fractions of root cells, leading to higher Cd concentrations in the root tissue. Xiangwanxian 12 also exhibited a decrease in Cd concentrations in the cell wall, organelles, and soluble fraction of root cells, resulting in lower Cd concentrations in the root tissue. Additionally, the expression of the OsNRAMP5 and OsHMA3 gene was significantly increased in Shaoxiang 100, while no significantly change in Yuzhenxiang and Xiangwanxian 12. These results provide important guidance on the impact of pH on Cd accumulation during the vegetative growth stage of different rice varieties.


Assuntos
Cádmio , Hidroponia , Oryza , Raízes de Plantas , Oryza/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/efeitos dos fármacos , Cádmio/metabolismo , Concentração de Íons de Hidrogênio , Raízes de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/efeitos dos fármacos , Brotos de Planta/metabolismo , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/efeitos dos fármacos
2.
Front Pediatr ; 12: 1436608, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39165488

RESUMO

Background: Anomalous pulmonary venous connection with malposition of septum primum (MSP) is a rare pediatric cardiovascular malformation. Although reports in the literature are scarce, accurate pre-operative imaging diagnosis is crucial for selecting the appropriate clinical intervention and determining the prognosis for affected children. Case description: In both case reports, the cardiovascular malformations were incidental findings. In the second case, an enlarged cardiac silhouette was observed on chest x-ray due to pneumonia, which was subsequently confirmed by ultrasound. Combined with computed tomography angiography examination, the diagnosis of MSP-type anomalous pulmonary venous connection was established. Conclusions: Comprehensive imaging examinations are essential in reducing misdiagnosis and achieving an accurate diagnosis of MSP-type anomalous pulmonary venous connection. The typical imaging findings for MSP-type anomalous pulmonary venous connection include absence or hypoplasia of the superior limbic band of the septum secundum, leftward displacement of the septum primum, and partial or total pulmonary vein drainage into the anatomical right atrium.

3.
Opt Lett ; 49(17): 5011-5014, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39208021

RESUMO

The fluorescence collection from single atoms and emitters has been extensively utilized in quantum information and quantum optics research. Here, we investigated the collection efficiency of an objective lens by drawing an analogy between the free-space beam (FSB) and a waveguide mode. We explored how efficiency is influenced by their thermal motion within a dipole trap. Furthermore, we introduce an effective energy fraction ratio to quantify potential imperfections in the focusing of the objective lens. Our results provide valuable insights for optimizing the fluorescence collection in single-atom experiments and highlight the importance of considering realistic experimental conditions when estimating achievable efficiencies.

4.
Front Pediatr ; 12: 1442347, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39205664

RESUMO

Background: Congenital pulmonary sequestration is a rare lung anomaly that can be classified as intralobar pulmonary sequestration or extralobar lung sequestration (ELS). Infradiaphragmatic pulmonary sequestration is a rare type of ELS. Furthermore, intrathoracic kidney (ITK) is a rare disease that can be associated with a congenital diaphragmatic hernia (CHD) in 0.25% of cases. We report the first case of infradiaphragmatic pulmonary sequestration and ITK associated with CDH in a child. Case report and management: The patient, male, aged 6 months, visited our hospital 2 months prior due to shortness of breath. Based on chest ultrasonography and enhanced computed tomography (CT) examination, infradiaphragmatic pulmonary sequestration and ITK were considered to be associated with CDH. The patient was admitted to our hospital for treatment. After admission, his blood pressure was 85/61 mmHg, there was no hematuria or proteinuria, creatinine was 14 µmol/L, and urea nitrogen was 2.96 mmol/L, all of which showed no abnormalities. A complete preoperative examination was performed prior to surgical treatment. Thoracoscopy revealed that the right kidney had herniated into the chest cavity on the posterolateral side of the diaphragm. The right kidney was returned to the abdominal cavity, the hernia sac was opened, and a bright red lesion tissue with clear boundaries and an abnormal blood vessel supply was observed. After cutting off the abnormal blood vessels, LigaSure TM was used to remove the diseased tissue, and the renal fat sacs and renal tissue were visible. Intermittent suturing of the hernia ring was performed to seal the diaphragmatic hernia. Postoperative pathological examination revealed infradiaphragmatic pulmonary sequestration. The postoperative recovery of the patient was smooth, and a chest CT scan at 2 months showed that the right kidney had returned to the abdominal cavity and the right diaphragm was in the normal position. Conclusion: Infradiaphragmatic pulmonary sequestration and ITK associated with CDH is extremely rare. A diagnosis and appropriate surgical planning can be developed using enhanced CT. For infradiaphragmatic pulmonary sequestration located at the top of the hernia sac in CHD, thoracoscopic resection of the infradiaphragmatic pulmonary sequestration and repair of the diaphragmatic hernia is feasible and effective.

5.
Chemosphere ; 363: 142903, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39029704

RESUMO

Selenium (Se) fortification is witnessed to simultaneously inhibit absorbing Cadmium (Cd) and Arsenic (As) by rice plants, but the mechanism is unclear. Here, the effects of Se on the root morphology, iron plaque (IP) content, soil Fe2+ content, radial oxygen loss (ROL), and enzyme activities of the rice plants in the soil contaminated by Cd and As were intensively investigated through the hydroponic and soil experiments. Se effectively alleviated the toxic effects of Cd and As on the plants and the dry weight, root length, and root width were increased by 203.18%, 33.41%, and 52.81%, respectively. It also elucidated that ROL was one of the key factors to elevate IP formation by Se and the specific pathways of Se enhancing ROL were identified. ROL of the plants in the experiment group treated by Se was increased 36.76%, and correspondingly IP was magnified 50.37%, compared to the groups with Cd and As. It was owing to Se significantly increased the root porosity (62.11%), facilitating O2 transport to the roots. Additionally, Se enhanced the activities of catalase (CAT) and superoxide dismutase (SOD) to promote the catalytic degradation of ROS induced by Cd and As stress. It indirectly increased O2 release in the rhizosphere, which benefit to form more robust IP serve as stronger barrier to Cd and As. The results of our study provide a novel molecular level insight for Se promoting root IP to block Cd and As uptake by the rice plants.


Assuntos
Arsênio , Cádmio , Ferro , Oryza , Raízes de Plantas , Selênio , Poluentes do Solo , Cádmio/toxicidade , Cádmio/metabolismo , Oryza/metabolismo , Oryza/efeitos dos fármacos , Arsênio/metabolismo , Arsênio/toxicidade , Selênio/farmacologia , Poluentes do Solo/toxicidade , Poluentes do Solo/metabolismo , Ferro/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Solo/química , Catalase/metabolismo , Rizosfera , Espécies Reativas de Oxigênio/metabolismo
6.
Environ Pollut ; 355: 124148, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38735457

RESUMO

Identifying the key influencing factors in soil available cadmium (Cd) is crucial for preventing the Cd accumulation in the food chain. However, current experimental methods and traditional prediction models for assessing available Cd are time-consuming and ineffective. In this study, machine learning (ML) models were developed to investigate the intricate interactions among soil properties, climate features, and available Cd, aiming to identify the key influencing factors. The optimal model was obtained through a combination of stratified sampling, Bayesian optimization, and 10-fold cross-validation. It was further explained through the utilization of permutation feature importance, 2D partial dependence plot, and 3D interaction plot. The findings revealed that pH, surface pressure, sensible heat net flux and organic matter content significantly influenced the Cd accumulation in the soil. By utilizing historical soil surveys and climate change data from China, this study predicted the spatial distribution trend of available Cd in the Chinese region, highlighting the primary areas with heightened Cd activity. These areas were primarily located in the eastern, southern, central, and northeastern China. This study introduces a novel methodology for comprehending the process of available Cd accumulation in soil. Furthermore, it provides recommendations and directions for the remediation and control of soil Cd pollution.


Assuntos
Cádmio , Monitoramento Ambiental , Aprendizado de Máquina , Poluentes do Solo , Solo , Cádmio/análise , Poluentes do Solo/análise , Solo/química , China , Monitoramento Ambiental/métodos , Clima , Teorema de Bayes , Mudança Climática
7.
Phys Rev Lett ; 132(16): 163603, 2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38701459

RESUMO

Phonon-based frequency combs that can be generated in the optical and microwave frequency domains have attracted much attention due to the small repetition rates and the simple setup. Here, we experimentally demonstrate a new type of phonon-based frequency comb in a silicon optomechanical crystal cavity including both a breathing mechanical mode (∼GHz) and flexural mechanical modes (tens of MHz). We observe strong mode competition between two approximate flexural mechanical modes, i.e., 77.19 and 90.17 MHz, resulting in only one preponderant lasing, while maintaining the lasing of the breathing mechanical mode. These simultaneous observations of two-mode phonon lasing state and significant mode competition are counterintuitive. We have formulated comprehensive theories to elucidate this phenomenon in response to this intriguing outcome. In particular, the self-pulse induced by the free carrier dispersion and thermo-optic effects interacts with two approximate flexural mechanical modes, resulting in the repetition rate of the comb frequency-locked to exact fractions of one of the flexural mechanical modes and the mode hopping between them. This phonon-based frequency comb has at least 260 comblines and a repetition rate as low as a simple fraction of the flexural mechanical frequency. Our demonstration offers an alternative optomechanical frequency comb for sensing, timing, and metrology applications.

8.
Opt Lett ; 49(7): 1729-1732, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38560848

RESUMO

Soliton microcombs are regarded as an ideal platform for applications such as optical communications, optical sensing, low-noise microwave sources, optical atomic clocks, and frequency synthesizers. Many of these applications require a broad comb spectrum that covers an octave, essential for implementing the f - 2f self-referencing techniques. In this work, we have successfully generated an octave-spanning soliton microcomb based on a z-cut thin-film lithium niobate (TFLN) microresonator. This achievement is realized under on-chip optical pumping at 340 mW and through extensive research into the broadening of dual dispersive waves (DWs). Furthermore, the repetition rate of the octave soliton microcomb is accurately measured using an electro-optic comb generated by an x-cut TFLN racetrack microresonator. Our results represent a crucial step toward the realization of practical, integrated, and fully stabilized soliton microcomb systems based on TFLN.

9.
Opt Express ; 32(7): 11202-11220, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38570974

RESUMO

On-chip microring resonators (MRRs) have been proposed to construct time-delayed reservoir computing (RC) systems, which offer promising configurations available for computation with high scalability, high-density computing, and easy fabrication. A single MRR, however, is inadequate to provide enough memory for the computation task with diverse memory requirements. Large memory requirements are satisfied by the RC system based on the MRR with optical feedback, but at the expense of its ultralong feedback waveguide. In this paper, a time-delayed RC is proposed by utilizing a silicon-based nonlinear MRR in conjunction with an array of linear MRRs. These linear MRRs possess a high quality factor, providing enough memory capacity for the RC system. We quantitatively analyze and assess the proposed RC structure's performance on three classical tasks with diverse memory requirements, i.e., the Narma 10, Mackey-Glass, and Santa Fe chaotic timeseries prediction tasks. The proposed system exhibits comparable performance to the system based on the MRR with optical feedback, when it comes to handling the Narma 10 task, which requires a significant memory capacity. Nevertheless, the dimension of the former is at least 350 times smaller than the latter. The proposed system lays a good foundation for the scalability and seamless integration of photonic RC.

10.
Opt Lett ; 49(3): 570-573, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38300061

RESUMO

Recently, there has been significant interest in the generation of coherent temporal solitons in optical microresonators. In this Letter, we present a demonstration of dissipative Kerr soliton generation in a microrod resonator using an auxiliary-laser-assisted thermal response control method. In addition, we are able to control the repetition rate of the soliton over a range of 200 kHz while maintaining the pump laser frequency, by applying external stress tuning. Through the precise control of the PZT voltage, we achieve a stability level of 3.9 × 10-10 for residual fluctuation of the repetition rate when averaged 1 s. Our platform offers precise tuning and locking capabilities for the repetition frequency of coherent mode-locked combs in microresonators. This advancement holds great potential for applications in spectroscopy and precision measurements.

11.
Environ Geochem Health ; 46(3): 86, 2024 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-38367055

RESUMO

Biochar adsorption of heavy metals has been a research hotspot, yet there has been limited reports on the effect of heavy metal interactions on adsorption efficiency in complex systems. In this study, the adsorbent was prepared by pyrolysis of rice straw loaded with manganese (BC-Mn). The interactions of Pb, Cd and As adsorption on BC-Mn were systematically studied. The results of the adsorption isotherms for the binary metal system revealed a competitive adsorption between Pb and Cd, resulting in decreased Pb (from 214.38 mg/g to 148.20 mg/g) and Cd (from 165.73 mg/g to 92.11 mg/g). A notable promotion occurred between As and Cd, showing an increase from 234.93 mg/g to 305.00 mg/g for As and 165.73 mg/g to 313.94 mg/g for Cd. In the ternary metal system, Pb inhibition did not counteract the promotion of Cd and As. Furthermore, the Langmuir isotherm effectively described BC-Mn's adsorption process in monometallic, binary, and ternary metal systems (R2 > 0.9294). Zeta and FTIR analyses revealed simultaneous competition between Pb and Cd for adsorption on BC-Mn's -OH sites. XPS analysis revealed that As adsorption by BC-Mn facilitated the conversion of MnO2 and MnO to MnOOH, resulting in increased hydroxyl radical production on BC-Mn's surface. Simultaneously, Cd combined with the adsorbed As to form ternary Cd-As-Mn complexes, which expedited the removal of Cd. These results help to provide theoretical support as well as technical support for the treatment of Pb-Cd-As contaminated wastewater.


Assuntos
Arsênio , Metais Pesados , Poluentes Químicos da Água , Cádmio , Manganês , Compostos de Manganês , Adsorção , Chumbo , Óxidos , Carvão Vegetal
12.
Opt Express ; 32(1): 313-324, 2024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-38175058

RESUMO

Magnetic-free nonreciprocal optical devices have attracted great attention in recent years. Here, we investigated the magnetic-free polarization rotation of light in an atom vapor cell. Two mechanisms of magnetic-free nonreciprocity have been realized in ensembles of hot atoms, including electromagnetically induced transparency and optically-induced magnetization. For a linearly polarized input probe light, a rotation angle up to 86.4° has been realized with external control and pump laser powers of 10 mW and is mainly attributed to the optically-induced magnetization effect. Our demonstration offers a new approach to realize nonreciprocal devices, which can be applied to solid-state atom ensembles and may be useful in photonic integrated circuits.

13.
Opt Express ; 31(23): 37722-37739, 2023 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-38017896

RESUMO

Machine learning-assisted spectroscopy analysis faces a prominent constraint in the form of insufficient spectral samples, which hinders its effectiveness. Meanwhile, there is a lack of effective algorithms to simulate synthetic spectra from limited samples of real spectra for regression models in continuous scenarios. In this study, we introduced a continuous conditional generative adversarial network (CcGAN) to autonomously generate synthetic spectra. The labels employed for generating the spectral data can be arbitrarily selected from within the range of labels associated with the real spectral data. Our approach effectively produced spectra using a small spectral dataset obtained from a self-interference microring resonator (SIMRR)-based sensor. The generated synthetic spectra were subjected to evaluation using principal component analysis, revealing an inability to discern them from the real spectra. Finally, to enhance the DNN regression model, these synthetic spectra are incorporated into the original training dataset as an augmentation technique. The results demonstrate that the synthetic spectra generated by CcGAN exhibit exceptional quality and significantly enhance the predictive performance of the DNN model. In conclusion, CcGAN exhibits promising potential in generating high-quality synthetic spectra and delivers a superior data augmentation effect for regression tasks.

14.
J Child Neurol ; 38(10-12): 617-621, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37700631

RESUMO

Objective: This study aimed to explore diagnostic performance of 3D-NERVE as an adjunct to electromyography for the assessment of brachial plexus injury in infants. Methods: Imaging of infants with brachial plexus injury using 3D-NERVE and/or 3D-STIR from 2019 to 2022 were reviewed. Images were evaluated between the 2 sequences for nerve-to-fat ratio, nerve-to-muscle ratio, muscle-to-fat ratio, fat suppression homogeneity, and display rate of brachial plexus branches. Results: This study included 37 infants who were referred for a clinical diagnosis of brachial plexus injury. A total of 21 infants accepted 3D-NERVE sequence scanning, and 16 infants accepted 3D-NERVE and 3D-STIR sequences scanning. The results of examination were generally consistent with electromyography. The 2 sequences were compared, yielding the following results. There were no pulsation artifacts (0/16), and 1 case with heterogeneous fat saturation (1/16) was seen on 3D-NERVE. There were no pulsation artifacts (0/16), and 5 cases with heterogeneous fat saturation (5/16) were seen on 3D-STIR. 3D-NERVE performed better (P < .05) for nerve-to-fat and nerve-to-muscle ratios compared with 3D-STIR, and no significant difference in the muscle-to-fat ratio (P > .05). The 3D-NERVE and STIR helped depict 100% (16/16) of the brachial roots and brachial plexus trunk. Brachial plexus bundles and brachial plexus branches were observed in 93.75% (15/16) and 68.75% (11/16) of the 3D-NERVE and 93.75% (15/16) and 62.5% (10/16) of the 3D-STIR, respectively. The differences were not statistically significant (P > .05). Conclusion: Nerve trauma was better visualized with the 3D-NERVE, which is an effective adjunct to electromyography for doctors to assess brachial plexus injury and consequently helps in better treatment planning.


Assuntos
Neuropatias do Plexo Braquial , Plexo Braquial , Humanos , Lactente , Eletromiografia , Imageamento por Ressonância Magnética/métodos , Plexo Braquial/diagnóstico por imagem , Plexo Braquial/lesões , Imageamento Tridimensional/métodos , Artefatos , Neuropatias do Plexo Braquial/diagnóstico por imagem
15.
Front Neurol ; 14: 1184864, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37602239

RESUMO

Background: Acute necrotizing encephalopathy (ANE) is a devastating neurologic condition that can arise following a variety of systemic infections, including influenza and SARS-Cov-2. The clinical features of COVID-19-associated ANE in pediatric patients based on multi-case data have not yet been described and remain obscure. We reviewed 12 pediatric patients to better describe the clinical features of ANE with COVID-19. Methods: We retrospectively collected and summarized the clinical features of ANE in children with COVID-19. Clinical data were collected from 12 children, including their general status, clinical symptoms, laboratory tests, and neuroimaging features. Results: Among the subjects, 10 were over 5 years old and they accounted for 83.33%. A large percentage of those affected (66.67%) were females. The major manifestations included fever (100%), impaired consciousness (100%), and convulsions (75%). We determined that increased interleukin (IL)-6 and IL-10, and tumor necrosis factor-α and interferon gamma were not predictive of severe ANE and mortality in children with COVID-19 in this study. All children presented with abnormal neuroimaging with multiple and symmetrically distributed lesions, involving the thalamus, basal ganglia, cerebellum, and brain hemispheres. Eight of the 12 children died, resulting in a mortality rate of 66.67%, and 75% of these children were females. Importantly, we found the timely administration of mannitol after an acute onset of convulsions or disturbance of consciousness may be decreased the high mortality induced by ANE children with COVID-19. Conclusion: COVID-19 associated with ANE in children is characterized by sudden symptom onset, rapid disease progression, and high mortality.

16.
Opt Express ; 31(10): 16781-16794, 2023 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-37157750

RESUMO

Whispering gallery mode (WGM) resonators provide an important platform for fine measurement thanks to their small size, high sensitivity, and fast response time. Nevertheless, traditional methods focus on tracking single-mode changes for measurement, and a great deal of information from other resonances is ignored and wasted. Here, we demonstrate that the proposed multimode sensing contains more Fisher information than single mode tracking and has great potential to achieve better performance. Based on a microbubble resonator, a temperature detection system has been built to systematically investigate the proposed multimode sensing method. After the multimode spectral signals are collected by the automated experimental setup, a machine learning algorithm is used to predict the unknown temperature by taking full advantage of multiple resonances. The results show the average error of 3.8 × 10-3°C within the range from 25.00°C to 40.00°C by employing a generalized regression neural network (GRNN). In addition, we have also discussed the influence of the consumed data resource on its predicted performance, such as the amount of training data and the case of different temperate ranges between the training and test data. With high accuracy and large dynamic range, this work paves the way for WGM resonator-based intelligent optical sensing.

17.
Front Pediatr ; 11: 1149785, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37205220

RESUMO

Background: Renal involvement is rarely reported in juvenile dermatomyositis and may be caused by the toxic effects of myoglobinuria or an autoimmune reaction. We report a case of dermatomyositis and nephrotic syndrome in a child to explore the association between juvenile dermatomyositis and renal involvement. Case presentation: An 8-year-old girl with skin rash, edema, proximal muscle weakness predominantly involving the lower extremities, low-grade fever, and foamy urine was admitted to our hospital. Her laboratory tests met the criteria of nephrotic syndrome. She had elevated creatine kinase and lactate dehydrogenase and was diagnosed with juvenile dermatomyositis after electromyography and muscle MRI. Anti-NXP2 antibodies were positive. Her proteinuria was relieved soon after treatment with prednisone and methotrexate, but her muscle strength progressively decreased. The disease was relieved after pulse methylprednisolone treatment and mycophenolate mofetil, but recurred after drug reduction with mild proteinuria. Adalimumab was used for treatment and helped reduce the doses of glucocorticoid and mycophenolate mofetil. Conclusion: Juvenile dermatomyositis may be one of the rare causes of nephrotic syndrome. The mechanism involved in JDM combined with renal injury may be multifactorial. Autoantibodies may play important roles in both muscle and renal damage.

18.
Opt Express ; 31(3): 4569-4579, 2023 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-36785421

RESUMO

The hybrid microcavity composed of different materials shows unique thermal-optical properties such as resonance frequency shift and small thermal noise fluctuations with the temperature variation. Here, we have fabricated the hybrid Si3N4 - TiO2 microring, which decreases the effective thermo-optical coefficients (TOC) from 23.2pm/K to 11.05pm/K due to the opposite TOC of these two materials. In this hybrid microring, we experimentally study the thermal dynamic with different input powers and scanning speeds. The distorted transmission and thermal oscillation are observed, which results from the non-uniform scanning speed and the different thermal relaxation times of the Si3N4 and the TiO2. We calibrate the distorted transmission spectrum for the resonance measurement at the reverse scanning direction and explain the thermal oscillation with a thermal-optical coupled model. Finally, we analyse the thermal oscillation condition and give the diagram about the oscillation region, which has significant guidance for the occurrence and avoidance of the thermal oscillation in practical applications.

19.
Opt Lett ; 48(4): 1064-1067, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36791011

RESUMO

Single atoms are interesting candidates for studying quantum optics and quantum information processing. Recently, trapping and manipulation of single atoms using tight optical dipole traps has generated considerable interest. Here we report an experimental investigation of the dynamics of atoms in a modified optical dipole trap with a backward propagating dipole trap beam, where a change in the two-atom collision rate by six times has been achieved. The theoretical model presented gives a prediction of high probabilities of few-atom loading rates under proper experimental conditions. This work provides an alternative approach to the control of the few-atom dynamics in a dipole trap and the study of the collective quantum optical effects of a few atoms.

20.
Nat Commun ; 14(1): 169, 2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36631455

RESUMO

The mode-locked microcomb offers a unique and compact solution for photonics applications, ranging from the optical communications, the optical clock, optical ranging, the precision spectroscopy, novel quantum light source, to photonic artificial intelligence. However, the photonic micro-structures are suffering from the perturbations arising from environment thermal noises and also laser-induced nonlinear effects, leading to the frequency instability of the generated comb. Here, a universal mechanism for fully stabilizing the microcomb is proposed and experimentally verified. By incorporating two global tuning approaches and the autonomous thermal locking mechanism, the pump laser frequency and repetition rate of the microcomb can be controlled independently in real-time without interrupting the microcomb generation. The high stability and controllability of the microcomb frequency enables its application in wavelength measurement with a precision of about 1 kHz. The approach for the full control of comb frequency could be applied in various microcomb platforms, and improve their performances in timing, spectroscopy, and sensing.

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