RESUMO
Genetic diversity is critical to crop breeding and improvement, and dissection of the genomic variation underlying agronomic traits can both assist breeding and give insight into basic biological mechanisms. Although recent genome analyses in plants reveal many structural variants (SVs), most current studies of crop genetic variation are dominated by single-nucleotide polymorphisms (SNPs). The extent of the impact of SVs on global trait variation, as well as their utility in genome-wide selection, is not yet understood. In this study, we built an SV data set based on whole-genome resequencing of diverse sorghum lines (n = 363), validated the correlation of photoperiod sensitivity and variety type, and identified SV hotspots underlying the divergent evolution of cellulosic and sweet sorghum. In addition, we showed the complementary contribution of SVs for heritability of traits related to sorghum adaptation. Importantly, inclusion of SV polymorphisms in association studies revealed genotype-phenotype associations not observed with SNPs alone. Three-way genome-wide association studies (GWAS) based on whole-genome SNP, SV, and integrated SNP + SV data sets showed substantial associations between SVs and sorghum traits. The addition of SVs to GWAS substantially increased heritability estimates for some traits, indicating their important contribution to functional allelic variation at the genome level. Our discovery of the widespread impacts of SVs on heritable gene expression variation could render a plausible mechanism for their disproportionate impact on phenotypic variation. This study expands our knowledge of SVs and emphasizes the extensive impacts of SVs on sorghum.
Assuntos
Variação Genética , Sorghum , Sorghum/genética , Estudo de Associação Genômica Ampla , Melhoramento Vegetal , Fenótipo , Grão Comestível/genética , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Autophagy is a catabolic cellular process that targets and eliminates superfluous cytoplasmic components via lysosomal degradation. This evolutionarily conserved process is tightly regulated at multiple levels as it is critical for the maintenance of homeostasis. Research in the past decade has established that dysregulation of autophagy plays a major role in various diseases, such as cancer and neurodegeneration. However, modulation of autophagy as a therapeutic strategy requires identification of key players that can fine tune the induction of autophagy without complete abrogation. In this Review, we summarize the recent discoveries on the mechanism of regulation of ATG (autophagy related) gene expression at the level of transcription, post transcription and translation. Furthermore, we briefly discuss the role of aberrant expression of ATG genes in the context of cancer.
Assuntos
Autofagia , Neoplasias , Humanos , Autofagia/genética , Homeostase , Neoplasias/genética , Citoplasma , Expressão GênicaRESUMO
KEY MESSAGE: A total of 389 and 344 QTLs were identified by GWAS and QTL mapping explaining accumulatively 32.2-65.0% and 23.7-63.4% of phenotypic variation for 14 shoot-borne root traits using more than 1300 individuals across multiple field trails. Efficient nutrient and water acquisition from soils depends on the root system architecture (RSA). However, the genetic determinants underlying RSA in maize remain largely unexplored. In this study, we conducted a comprehensive genetic analysis for 14 shoot-borne root traits using 513 inbred lines and 800 individuals from four recombinant inbred line (RIL) populations at the mature stage across multiple field trails. Our analysis revealed substantial phenotypic variation for these 14 root traits, with a total of 389 and 344 QTLs identified through genome-wide association analysis (GWAS) and linkage analysis, respectively. These QTLs collectively explained 32.2-65.0% and 23.7-63.4% of the trait variation within each population. Several a priori candidate genes involved in auxin and cytokinin signaling pathways, such as IAA26, ARF2, LBD37 and CKX3, were found to co-localize with these loci. In addition, a total of 69 transcription factors (TFs) from 27 TF families (MYB, NAC, bZIP, bHLH and WRKY) were found for shoot-borne root traits. A total of 19 genes including PIN3, LBD15, IAA32, IAA38 and ARR12 and 19 GWAS signals were overlapped with selective sweeps. Further, significant additive effects were found for root traits, and pyramiding the favorable alleles could enhance maize root development. These findings could contribute to understand the genetic basis of root development and evolution, and provided an important genetic resource for the genetic improvement of root traits in maize.
Assuntos
Estudo de Associação Genômica Ampla , Zea mays , Humanos , Zea mays/genética , Genômica , Mapeamento Cromossômico , AlelosRESUMO
OBJECTIVE: To analyze the clinical characteristics of laryngomalacia in Chinese children and explore the surgical efficacy and factors influencing severe laryngomalacia. METHODS: Children (0-18 years) diagnosed with laryngomalacia in our hospital from January 2016 to January 2022 were enrolled in this study. Clinical data of patients, including general conditions, clinical symptoms, grading and classification, medical comorbidities, surgical efficacy, and the risk factors influencing severe laryngomalacia were retrospectively analyzed. RESULTS: A total of 1810 children were enrolled (male:female; 2.02:1), among which most were infants under 1 year (77.18%). Inspiratory laryngeal stridor (69.56%) was the most common symptom. Most patients had mild laryngomalacia (79.28%), with type IV laryngomalacia being the most common classification (52.27%). Congenital heart disease (37.85%) was the most common medical comorbidity. A total of 168 severe laryngomalacia cases were treated via supraglottoplasty with an effective rate of 83.93%. Notably, preterm birth (OR = 3.868, 95% CI 1.340 ~ 11.168), low birth weight (OR = 4.517, 95% CI 1.477 ~ 13.819) and medical comorbidities (OR = 7.219, 95% CI 2.534 ~ 20.564) were independent risk factors for poor prognosis (P < 0.05). CONCLUSION: Laryngomalacia is common among infants under the age of one, and it is mostly characterized by inspiratory laryngeal stridor with various medical comorbidity. Supraglottoplasty is the first treatment choice for severe laryngomalacia cases with high success rates. However, premature delivery, low birth weight, and medical comorbidities significantly affect the efficacy of surgery.
Assuntos
Laringomalácia , Laringe , Nascimento Prematuro , Lactente , Criança , Humanos , Recém-Nascido , Masculino , Feminino , Laringomalácia/complicações , Laringomalácia/diagnóstico , Laringomalácia/cirurgia , Estudos Retrospectivos , Sons Respiratórios/etiologia , Resultado do Tratamento , Glote/cirurgiaRESUMO
In this paper, the green synthesis of isoeugenol methyl ether (IEME) from eugenol by O-methylation and isomerization is completed using a one-step green process. In the methylation reaction, dimethyl carbonate (DMC) was used as a green chemistry reagent instead of the traditional harmful methylation reagents, in accordance with the current concept of green chemistry. The phase transfer catalyst (PTC) polyethylene glycol 800 (PEG-800) was introduced into the isomerization reaction to break the barrier of difficult contact between solid and liquid phases and drastically reduce the reaction conditions by shortening the reaction time and reducing the alkalinity of the reaction system. The catalytic systems for the one-step green synthesis of IEME were screened, and it was shown that the catalytic system "K2CO3 + PEG-800" was the most effective. The effects of reaction temperature, n(DMC):n(eugenol) ratio, n(PEG-800):n(eugenol) ratio, and n(K2CO3):n(eugenol) ratio on eugenol conversion, IEME yield, and IEME selectivity were investigated. The results showed that the best reaction was achieved at a reaction temperature of 140 °C, a reaction time of 3 h, a DMC drip rate of 0.09 mL/min, and n(eugenol):n(DMC):n(K2CO3):n(PEG-800) = 1:3:0.09:0.08. As a result of the conversion of 93.1% of eugenol to IEME, a yield of 86.1% IEME as well as 91.6% IEME selectivity were obtained.
RESUMO
The growing concern about migratory birds potentially spreading ticks due to global warming has become a significant issue. The city of Nantong in this study is situated along the East Asia-Australasian Flyway (EAAF), with numerous wetlands serving as roosting sites for migratory birds. We conducted an investigation of hard ticks and determined the phylogenetic characteristics of tick species in this city. We utilized three different genes for our study: the mitochondrial cytochrome oxidase subunit 1 (COX1) gene, the second internal transcribed spacer (ITS2), and the mitochondrial small subunit rRNA (12 S rRNA) gene. The predominant tick species were Haemaphysalis flava (H. flava) and Haemaphysalis longicornis (H. longicornis). Additionally, specimens of Haemaphysalis campanulata (H. campanulata) and Rhipicephalus sanguineus (R. sanguineus) were collected. The H. flava specimens in this study showed a close genetic relationship with those from inland provinces of China, as well as South Korea and Japan. Furthermore, samples of H. longicornis exhibited a close genetic relationship with those from South Korea, Japan, Australia, and the USA, as well as specific provinces in China. Furthermore, R. sanguineus specimens captured in Nantong showed genetic similarities with specimens from Egypt, Nigeria, and Argentina.
Assuntos
Migração Animal , Aves , Complexo IV da Cadeia de Transporte de Elétrons , Ixodidae , Filogenia , Animais , China , Ixodidae/genética , Ixodidae/classificação , Ixodidae/fisiologia , Complexo IV da Cadeia de Transporte de Elétrons/genética , Complexo IV da Cadeia de Transporte de Elétrons/análise , RNA Ribossômico/genética , RNA Ribossômico/análise , Ninfa/crescimento & desenvolvimento , Ninfa/classificação , Ninfa/genética , Ninfa/fisiologia , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/análise , DNA Espaçador Ribossômico/análiseRESUMO
Plant architecture and stress tolerance play important roles in rice breeding. Specific leaf morphologies and ideal plant architecture can effectively improve both abiotic stress resistance and rice grain yield. However, the mechanism by which plants simultaneously regulate leaf morphogenesis and stress resistance remains elusive. Here, we report that SRL10, which encodes a double-stranded RNA-binding protein, regulates leaf morphology and thermotolerance in rice through alteration of microRNA biogenesis. The srl10 mutant had a semi-rolled leaf phenotype and elevated sensitivity to high temperature. SRL10 directly interacted with catalase isozyme B (CATB), and the two proteins mutually increased one other's stability to enhance hydrogen peroxide (H2 O2 ) scavenging, thereby contributing to thermotolerance. The natural Hap3 (AGC) type of SRL10 allele was found to be present in the majority of aus rice accessions, and was identified as a thermotolerant allele under high temperature stress in both the field and the growth chamber. Moreover, the seed-setting rate was 3.19 times higher and grain yield per plant was 1.68 times higher in near-isogenic line (NIL) carrying Hap3 allele compared to plants carrying Hap1 allele under heat stress. Collectively, these results reveal a new locus of interest and define a novel SRL10-CATB based regulatory mechanism for developing cultivars with high temperature tolerance and stable yield. Furthermore, our findings provide a theoretical basis for simultaneous breeding for plant architecture and stress resistance.
Assuntos
Oryza , Termotolerância , Termotolerância/genética , Oryza/metabolismo , Catalase/genética , Catalase/metabolismo , Isoenzimas/metabolismo , Melhoramento Vegetal , Grão Comestível , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Folhas de Planta/genética , Folhas de Planta/metabolismoRESUMO
Stalk lodging, which is generally determined by stalk strength, results in considerable yield loss and has become a primary threat to maize (Zea mays) yield under high-density planting. However, the molecular genetic basis of maize stalk strength remains unclear, and improvement methods remain inefficient. Here, we combined map-based cloning and association mapping and identified the gene stiff1 underlying a major quantitative trait locus for stalk strength in maize. A 27.2-kb transposable element insertion was present in the promoter of the stiff1 gene, which encodes an F-box domain protein. This transposable element insertion repressed the transcription of stiff1, leading to the increased cellulose and lignin contents in the cell wall and consequently greater stalk strength. Furthermore, a precisely edited allele of stiff1 generated through the CRISPR/Cas9 system resulted in plants with a stronger stalk than the unedited control. Nucleotide diversity analysis revealed that the promoter of stiff1 was under strong selection in the maize stiff-stalk group. Our cloning of stiff1 reveals a case in which a transposable element played an important role in maize improvement. The identification of stiff1 and our edited stiff1 allele pave the way for efficient improvement of maize stalk strength.
Assuntos
Elementos de DNA Transponíveis/genética , Regiões Promotoras Genéticas , Zea mays/genética , Alelos , Sistemas CRISPR-Cas , Parede Celular/metabolismo , Mapeamento Cromossômico , Genes de Plantas , Lignina/metabolismo , Fenótipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas , Análise de Sequência , Transformação GenéticaRESUMO
Metalenses have been widely investigated for their features of high design freedom. For practical applications, it is necessary to maximize the efficiency of the metalens. However, it is a great challenge to realize both a high numerical aperture (NA) and high-efficiency metalens in the community. Here, we introduce a method to design a hybrid metalens with a large numerical aperture and high focusing efficiency at terahertz frequency. The hybrid metalens consists of gradient metasurfaces in the central area and metagrating in the peripheral area to achieve high-efficiency beam focusing. To verify this concept, a hybrid metalens with a numerical aperture of 0.95 was designed at λ = 118.8â µm. The simulation results demonstrate that the focusing efficiency of the hybrid metalens is 65.8%. The experimental results show that the designed metalens is able to increase the focusing efficiency from 22.8% to 41.7%. The full widths at half maxima (FWHMs) of the focused spots of the hybrid metalens in the x direction and y direction are 0.72λ and 0.45λ, respectively. The proposed high-efficiency hybrid metalens has promising application prospects in various applications of a complex optical system.
RESUMO
PURPOSE: To provide better evidence of the efficacy and safety of preoperative halo-pelvic traction on the improvements of deformity and pulmonary functions in patients with severe scoliosis. METHODS: Electronic database searches were conducted including the Cochrane Library, PubMed, Web of Science and Embase. All studies of halo-pelvic traction for the management of severe spinal deformity were included. We referred to a list of four criteria developed by the Agency for Healthcare Research and Quality (AHRQ) to assess the quality of included studies. The meta-analysis was performed using RevMan 5.4 software. RESULTS: Based on the study selection criteria, a total of eight articles consisting of a total of 210 patients were included. Statistically significant differences were found in coronal Cobb angle (P < 0.001), sagittal Cobb angle (P < 0.001) and height (P < 0.001) between pre- and post-traction. Sensitivity analysis was conducted, and there were substantial changes in heterogeneity with preoperative thoracoplasty subgroup in coronal Cobb angle (P < 0.001). Three trials including 74 subjects reported FVC and FEV1 predicted value between pre- and post-traction. There were statistically significant differences in FVC, FVC%, FEV1 and FEV1% (P < 0.001). The complication rate was 6.6-26.7%, and symptoms disappeared after reasonable traction strategy and intensive care. CONCLUSIONS: Preoperative halo-pelvic traction achieved significant improvements in spinal deformity and pulmonary functions, with minor and curable complications. Thus, it is an effective and safe solution before surgery and may be the optimal choice for severe scoliosis. In light of the heterogeneity and limitations, future researches are needed to better determine the long-term efficacy on comprehensive assessment and to explore the appropriate traction system.
Assuntos
Escoliose , Toracoplastia , Humanos , Tração , Escoliose/cirurgia , Bases de Dados Factuais , Software , Resultado do Tratamento , Estudos RetrospectivosRESUMO
PURPOSE: To evaluate the feasibility and clarify the appropriate indications for extubation immediately after single-stage laryngotracheal reconstruction (SS-LTR) in pediatric subglottic stenosis (SGS). METHODS: A retrospective study was performed from July 2017 to July 2022. All patients underwent SS-LTR with anterior costal cartilage graft. Information such as demographics, comorbidities, history of intubation or tracheostomy, Classification and grading of airway stenosis, the operation-specific decannulation rate and overall decannulation rate were analyzed. RESULTS: Twenty-two patients with simple SGS were identified. The median age at SS-LTR was 19 months (IQR = 18.5 months). Fourteen patients (63.6%) were intubated prior to the presentation of symptoms. Fourteen patients (63.6%) required preoperative tracheostomy to maintain a secure airway. Eight patients (36.4%) had congenital SGS, 10 patients (45.5%) had acquired SGS, and 4 patients (18.2%) had mixed SGS. Three patients had Grade II stenosis. Nineteen patients had Grade III stenosis. Comorbidities were found in 10 patients (45.5%). Major comorbidities were pneumonia. Congenital airway anomalies were found in 6 patients (27.3%). After anesthesia, all 22 patients were successfully extubated and returned to the general ward. Twenty patients had a satisfactory airway after SS-LTR. Two patients required reintubation or tracheostomy after operation. Operation-specific decannulation rate was 90.9%. The overall decannulation rate is 100%. CONCLUSION: SS-LTR with anterior costal cartilage graft is an effective method to treat simple SGS ranging from Grades I to III in children. Extubation immediately after surgery is safe and feasible.
Assuntos
Extubação , Laringoestenose , Criança , Humanos , Lactente , Estudos Retrospectivos , Constrição Patológica , Resultado do Tratamento , Laringoestenose/cirurgiaRESUMO
One of the key challenges of improving clinical outcomes of antibody drug conjugates (ADCs) is overcoming cancer resistance to the antibody and/or drug components of ADCs, and hence the need for ADC platforms with high combinatory flexibility. Here, we introduce the use of self-assembled left-handed DNA (L-DNA) oligonucleotides to link combinatory single-domain antibodies and toxin payloads for tunable and adaptive delivery of ADCs. We demonstrate that the method allows convenient construction of a library of ADCs with multi-specific targeting, multi-specific payloads, and exact drug-antibody ratio. The newly constructed ADCs with L-DNA scaffold showed favorable properties of in vitro cell cytotoxicity and in vivo suppression and eradication of solid tumors. Collectively, our data suggest that the L-DNA based modular ADC (MADC) platform is a viable option for generating therapeutic ADCs and for potentially expanding ADC therapeutic window via multi-specificity.
Assuntos
Antineoplásicos , Imunoconjugados , Neoplasias , Humanos , Anticorpos , DNA , Antineoplásicos/farmacologiaRESUMO
Leaf morphology is one of the important traits related to ideal plant architecture and is an important factor determining rice stress resistance, which directly affects yield. Wax layers form a barrier to protect plants from different environmental stresses. However, the regulatory effect of wax synthesis genes on leaf morphology and salt tolerance is not well-understood. In this study, we identified a rice mutant, leaf tip rumpled 1 (ltr1), in a mutant library of the classic japonica variety Nipponbare. Phenotypic investigation of NPB and ltr1 suggested that ltr1 showed rumpled leaf with uneven distribution of bulliform cells and sclerenchyma cells, and disordered vascular bundles. A decrease in seed-setting rate in ltr1 led to decreased per-plant grain yield. Moreover, ltr1 was sensitive to salt stress, and LTR1 was strongly induced by salt stress. Map-based cloning of LTR1 showed that there was a 2-bp deletion in the eighth exon of LOC_Os02g40784 in ltr1, resulting in a frameshift mutation and early termination of transcription. Subsequently, the candidate gene was confirmed using complementation, overexpression, and knockout analysis of LOC_Os02g40784. Functional analysis of LTR1 showed that it was a wax synthesis gene and constitutively expressed in entire tissues with higher relative expression level in leaves and panicles. Moreover, overexpression of LTR1 enhanced yield in rice and LTR1 positively regulates salt stress by affecting water and ion homeostasis. These results lay a theoretical foundation for exploring the molecular mechanism of leaf morphogenesis and stress response, providing a new potential strategy for stress-tolerance breeding.
Assuntos
Oryza , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Oryza/metabolismo , Melhoramento Vegetal , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Tolerância ao Sal/genéticaRESUMO
Plasmonic lithography can utilize evanescent waves to produce subdiffraction patterns. However, the high loss and shallow depth of patterns severely obstruct its application in practice. In this work, a large focal depth is achieved for deep subwavelength lithography. It is accomplished by employing radially polarized light to excite surface plasmons on a concentric annular grating and combining designed epsilon-near-zero metamaterial to select a high spatial frequency mode, which can shape an evanescent Bessel beam in a photoresist (PR). Moreover, the intensity distribution of the subdiffraction beam can be further enhanced and uniformized by adding reflective layers. It is shown that a needle-like beam with a focal depth of over 500 nm (1.23λ) is formed in the PR layer, and the full width at half maximum of the beam is widened from only 80 nm (0.2λ) to 94 nm (0.23λ). The analyses indicate that this design is applicable for direct writing lithography to produce super-resolution patterns with small feature size, high aspect ratio, and strong field intensity.
RESUMO
The maize nodal root system plays a crucial role in the development of the aboveground plant and determines the yield via the uptake of water and nutrients in the field. However, the genetic architecture of the maize nodal root system is not well understood, and it has become the 'dark matter' of maize genetics. Here, a large teosinte-maize population was analyzed, and high-resolution mapping revealed that 62 out of 133 quantitative trait loci (QTLs), accounting for approximately half of the total genetic variation in nodal root number, were derived from QTLs for flowering time, which was further validated through a transgenic analysis and a genome-wide association study. However, only 16% of the total genetic variation in nodal root number was derived from QTLs for plant height. These results gave a hint that flowering time played a key role in shaping nodal root number via indirect selection during maize domestication. Our results also supported that more aerial nodal roots and fewer crown roots might be favored in temperate maize, and this root architecture might efficiently improve root-lodging resistance and the ability to take up deep water and nitrogen under dense planting.
Assuntos
Genes de Plantas/genética , Raízes de Plantas/genética , Locos de Características Quantitativas/genética , Zea mays/genética , Mapeamento Cromossômico , Domesticação , Flores/genética , Flores/crescimento & desenvolvimento , Variação Genética , Estudo de Associação Genômica Ampla , Fenótipo , Raízes de Plantas/crescimento & desenvolvimento , Seleção Genética , Fatores de Tempo , Zea mays/crescimento & desenvolvimentoRESUMO
Independent manipulation of phase and polarization of optical fields is of great interest in various applications, including vector-field generation, optical tweezers, and nanolithography. The integration of phase and polarization manipulation on a single optical device may greatly simplify optical systems and eases optical alignment. In this Letter, a family of reflective cross-shaped quarter-wave birefringent metasurfaces is proposed to achieve full control of polarization and phase of reflected waves. Based on the proposed metasurfaces, two meta-mirrors are designed with integrated functions of polarization conversion and sub-diffraction focusing. Numerical investigations also reveal the achromatic focusing performance of the two meta-mirrors. The proposed metasurfaces with independent manipulation of polarization and phase provide flexible building blocks for constructing complicated vector optical fields.
RESUMO
In order to realize the function of subdiffraction focusing using a single flat lens, a special metalens is proposed to modulate the circularly polarized light. Initially, the analyses indicate that the phase shift can cover [0,2π] by changing the rotation angle of a quadrangular-frustum pyramid-shaped structure from 0° to 180°, while the average amplitude transmittance can reach 96% at the wavelength of λ=1550 nm. Then, a flat metalens is designed by carefully arranging the quadrangular-frustum pyramid-shaped structures. The simulated results show that a focal spot could be obtained at the focal length of about f=2.87λ, and the focusing efficiency is â¼14.9%. Meanwhile, the full width at half maximum (FWHM) of the focusing spot is only 0.48λ, which is smaller than the diffraction limit. Furthermore, this designed metalens can function comparatively with a conventional lens in one-to-one imaging.
RESUMO
Sub-diffraction quasi-non-diffracting beams with sub-wavelength transverse size are attractive for applications such as optical nano-manipulation, optical nano-fabrication, optical high-density storage, and optical super-resolution microscopy. In this paper, we proposed an optimization-free design approach and demonstrated the possibility of generating sub-diffraction quasi-non-diffracting beams with sub-wavelength size for different polarizations by a binary-phase Fresnel planar lens. More importantly, the optimization-free method significantly simplifies the design procedure and the generation of sub-diffracting quasi-non-diffracting beams. Utilizing the concept of normalized angular spectrum compression, for wavelength λ0 = 632.8 nm, a binary-phase Fresnel planar lens was designed and fabricated. The experimental results show that the sub-diffraction transverse size and the non-diffracting propagation distances are 0.40λ0-0.54λ0 and 90λ0, 0.43λ0-0.54λ0 and 73λ0, and 0.34λ0-0.41λ0 and 80λ0 for the generated quasi-non-diffracting beams with circular, longitudinal, and azimuthal polarizations, respectively.
RESUMO
A three-dimensional (3D) hollow spot is of great interest for a wide variety of applications such as microscopy, lithography, data storage, optical manipulation, and optical manufacturing. Based on conventional high-numerical-aperture objective lenses, various methods have been proposed for the generation of 3D hollow spots for different polarizations. However, conventional optics are bulky, costly, and difficult to integrate. More importantly, they are diffraction-limited in nature. Owing to their unique properties of small size, light weight, and ease of integration, planar lenses have become attractive as components in the development of novel optical devices. Utilizing the concept of super-oscillation, planar lenses have already shown great potential in the generation of sub-diffraction, or even of super-oscillatory features, in propagating optical waves. In this paper, we propose a binary-phase planar lens with an ultra-long focal length (300λ) for the generation of a 3D hollow spot with a cylindrical vector wave. In addition, we experimentally demonstrate the formation of such a hollow spot with a sub-diffraction transverse size of 0.546λ (smaller than the diffraction limit of 0.5λ/NA, where NA denotes the lens numerical aperture) and a longitudinal size of 1.585λ. The ratio of central minimum intensity to the central ring peak intensity is less than 3.7%. Such a planar lens provides a promising way to achieve tight 3D optical confinement for different uses that might find applications in super-resolution microscopy, nano-lithography, high-density data storage, nano-particle optical manipulation, and nano-optical manufacturing.
RESUMO
Terahertz wave imaging offers promising properties for non-destructive testing applications in the areas of homeland security, medicine, and industrial inspection. However, conventional optical lenses are heavy and bulky and difficult to integrate. An all-dielectric metasurface provides an attractive way to realize a planar lens of light weight that is ultrathin and offers ease of integration. Terahertz lenses based on various metasurfaces have been studied, especially for the application of wave focusing, while there are few experimental demonstrations of terahertz wave imaging lenses based on an all-dielectric metasurface. In the present work, we propose a metalens based on an all-dielectric metasurface with a sub-wavelength unit size of 0.39λ for terahertz wave imaging and experimentally demonstrate its performance in focusing and imaging. A large numerical aperture metalens was fabricated with a focal length of 300λ, radius of 300λ, and numerical aperture of 0.707. The experimental results show that the lens can focus THz waves with an incident angle up to 48°. More importantly, clear terahertz wave images of different objects were obtained for both different cases of forward- and inverse-incident directions, which demonstrate the reversibility of the metalens for imaging. Such a metalens provides a way for realization of all-planar-lens THz imaging system, and might find application in terahertz wave imaging, information processing, microscopy, and others.