Grating-based metasurfaces for ultra-narrow near-infrared bandpass filtering with wide out-of-band suppression.

Here, we present a straightforward strategy for designing silicon grating-based metasurfaces tailored for narrow near-infrared bandpass filtering. By selecting appropriate structural parameters for the grating and including periodic groove perturbations within each grating slit, transverse guided mode resonances (GMRs) propagating perpendicular and parallel to the grating slit are created to provide wide out-of-band suppression and high-Q filter responses, respectively. The destructive and constructive interference between radiations from groove perturbations are then introduced to eliminate all GMRs except one, producing a single-band bandpass filter. Simply adjusting the period of the groove perturbations allows precise tuning of the passband's central wavelength across the operational spectral range from 1350 nm to 1750nm, throughout which the passband exhibits a Q-factor exceeding 9,000 and the attenuation level outside the passband remains below 1%. Furthermore, our proposed narrow bandpass filters are found to be robust against the potential fabrication imperfections, such as variations in groove size and position.

The Causes Behind the Survival Paradox in Non-Metastatic Colorectal Cancer Patients and its Impact on the Treatment Regimen: A Retrospective Cohort Study.

BACKGROUND: The survival paradox (ie, the prognosis of the population at earlier tumor stages is worse than that of the population at later stages) has been observed in colorectal cancer based on the American Joint Committee on Cancer Tumor-Nodes-Metastases staging system. We aimed to clarify the reason for the survival paradox and its impact on patient treatment. METHODS: We conducted a retrospective study analyzing eligible patients with colorectal cancer from the Surveillance, Epidemiology, and End Results database and Zhejiang Cancer Hospital between 2010 and 2019. Adjusting for confounders using propensity score matching allowed confirmation of the effect of staging on the survival paradox. RESULTS: Based on the Surveillance, Epidemiology, and End Results database, the subgroups with survival paradox might be IIB/C versus IIIA, IIA versus IIIA, and T4N0 (IIB/C) versus T3N1 (IIIB). After propensity score matching, stage IIB/C still had a worse prognosis than stage IIIA (5-year overall survival: 69.3% vs 78.5%, P < .001). Interestingly, the proportion of stage IIIA people receiving chemotherapy was higher than that of stage IIB/C (P < .001), and logistic regression models showed that staging was the reason for deciding whether a patient receives chemotherapy or not. These phenomena between stage IIB/C and IIIA were verified in the local database. CONCLUSION: These results suggested that the survival paradox was mainly due to underestimation of stage T4 weights or overestimation of stage N1 weights, and the low proportion of chemotherapy in patients with T4N0M0 colorectal cancer (proven to be more malignant than stage IIIA) might be related to the assignment to earlier stages, resulting in a lack of attention and poor compliance to chemotherapy in these patients.

Metasurfaces enabled polarization-multiplexing heralded single photon imaging.

Quantum imaging has non-negligible advantages in terms of sensitivity, signal-to-noise ratio, and novel imaging schemes. Based on metasurfaces, the information density and stability of the quantum imaging system can be further improved. Here we experimentally demonstrate that two patterns, simultaneously and independently superimposed on a high-efficiency dielectric metasurface, can be remotely switched via polarization-entangled photon pairs. Furthermore, using the time-correlated property of entangled photon pairs, the information carried by quantum light can be remarkably discriminated from background noise. This work confirms that the phase manipulation of quantum light with metasurfaces has a huge potential in the field of quantum imaging, quantum state tomography, and also promises real-world quantum metasurface devices.

Upregulation of HMGB1 in tumor-associated macrophages induced by tumor cell-derived lactate further promotes colorectal cancer progression.

BACKGROUND: Lactate accumulation leads to an acidic tumor microenvironment (TME), in turn promoting colorectal cancer (CRC) progression. Tumor-associated macrophages (TAMs) are the predominant cells in TME. This study aimed to reveal the regulation mechanism of CRC cell-derived lactate on TAMs and explore the mechanism underlying lactate accumulation-induced aggravation in CRC. METHODS: Cell growth and metastasis were evaluated by colony formation, Transwell, and wound healing assays. Western blot and RT-qPCR were applied to determine the protein and mRNA expression. Flow cytometry was used to analyze the polarization state and apoptotic rate of macrophages induced in THP-1 cells. The lactate in the cell supernatant was quantified using an ELISA kit. Immunofluorescence was performed to visualize the location of High Mobility Group Box 1 (HMGB1). H&E and Ki67 staining assays were used to assess tumorigenesis in nude mice bearing ectopic tumors. RESULTS: Cell growth and metastasis were promoted in the hypoxic CRC cells. The hypoxic cell supernatant stimulated the M2-type polarization of macrophages. The lactate level increased in hypoxic cancer cells. However, the inhibition of lactate using 3-hydroxy-butyrate (3-OBA) reversed the effects of hypoxia. Also, macrophages showed no promoting effect on cancer cell growth and migration in the presence of 3-OBA. HMGB1 was secreted into the extracellular space of lactate-induced macrophages, further enhancing the malignant behaviors of cancer cells. ERK, EMT, and Wnt signaling pathways were activated in cancer cells due to HMGB1 upregulation. CONCLUSIONS: The lactate metabolized by cancer cells stimulated M2 polarization and HMGB1 secretion by macrophages, aggravating the carcinogenic behaviors of cancer cells.

High-Q filtering and dynamic modulation in all-dielectric metasurfaces induced by quasi-BIC.

The all-dielectric metasurfaces can significantly reduce the volume of optical components while having low loss and high performance, which has become a research hotspot in recent years. However, due to the complexity of metasurface geometric design, it is challenging to realize dynamic modulation on all-dielectric metasurface optical elements. Here, we propose a high quality factor (high-Q) pass-band filter designed by introducing the quasi-bound states in the continuum (quasi-BIC) into the silicon array phase-gradient metasurfaces. Our simulations show that due to the quasi-BIC effect only a high-Q resonance with the linewidth less than 1 nm and the corresponding Q value of ∼37000 could transmit along the zeroth order direction, which could be used for ultra-narrow linewidth filtering. Furthermore, our simulations present that the near-fields of the waveguide modes supported by the silicon arrays are partially distributed inside the indium tin oxide (ITO) substrate, which makes it possible to dynamically tune the central wavelength of our proposed filter by varying the ITO refractive index.

Computational Dissection of the Role of Trp305 in the Regulation of the Death-Associated Protein Kinase-Calmodulin Interaction.

Death-associated protein kinase 1 (DAPK1), as a calcium/calmodulin (CaM) regulated serine/threonine kinase, functions in apoptotic and autophagy pathways and represents an interesting drug target for inflammatory bowel disease and Alzheimer's disease. The crystal structure of the DAPK1 catalytic domain and the autoregulatory domain (ARD) in complex with CaM provides an understanding of CaM-dependent regulation of DAPK1 activity. However, the molecular basis of how distinct Trp305 (W305Y and W305D) mutations in the ARD modulate different DAPK1 activities remains unknown. Here, we performed multiple, µs-length molecular dynamics (MD) simulations of the DAPK1-CaM complex in three different (wild-type, W305Y, and W305D) states. MD simulations showed that the overall structural complex did not change significantly in the wild-type and W305Y systems, but underwent obvious conformational alteration in the W305D system. Dynamical cross-correlation and principal component analyses revealed that the W305D mutation enhanced the anti-correlated motions between the DAPK1 and CaM and sampled a broader distribution of conformational space relative to the wild-type and W305Y systems. Structural and energetical analyses further exhibited that CaM binding was unfavored in response to the W305D mutation, resulting in the decreased binding of CaM to the W305D mutant. Furthermore, the hydrogen bonds and salt bridges responsible for the loss of CaM binding on the interface of the DAPK1-CaM complex were identified in the W305D mutant. This result may provide insights into the key role of Trp305 in the regulation of CaM-mediated DAPK1 activity.

Dielectric loading method for doubly resonant enhancement of third-harmonic generation from complementary split-ring resonators.

Nonlinear optical response could be greatly enhanced when metasurfaces support plasmonic resonances at both fundamental and harmonic wavelengths. However, it is still challenging to fulfill the doubly resonant condition. Here, we propose a dielectric-loading method, which simply coats a conformal thin dielectric layer onto the plasmonic metasurfaces, to introduce an additional degree of freedom and make the doubly resonant condition easily fulfilled. We demonstrate that by simultaneously tuning the thickness of the coated dielectric layer and the geometrical parameters of the gold complementary split-ring resonators (CSRRs), the doubly resonant enhancement of third harmonic generation (THG) could be achieved for any given fundamental wavelengths. We also experimentally verify this concept and show that the THG intensity in the dielectric-loaded CSRRs under the doubly resonant condition could be further increased about 3 times as compared with the case of the conventional CSRRs.

Enhanced second-harmonic generation from gold complementary split-ring resonators with a dielectric coating.

We experimentally and theoretically investigate the influence of alumina coating on the second-harmonic generation (SHG) from split-ring resonator shaped air apertures engraved in a gold film, which are also termed as complementary split-ring resonators (CSRRs). By coating the CSRR arrays with alumina film of certain thickness, we precisely tune their electric diploe resonances (EDRs) to overlap the fundamental wavelength (FW) and realize the EDR enhanced SHG process. On this basis, by shortening the arm length of the CSRRs and then coating them with a certain thickness of the alumina film, we have achieved an SHG enhancement of nearly 1.2-fold in experiment and 8-fold in simulation compared to the CSRR array with an unshortened arm length. We attributed it to the improvement of the magnitude of the effective nonlinear source due to the realization of a doubly-resonant condition. As a flexible method, dielectric coating not only is beneficial to precisely and dynamically optimize the linear and nonlinear properties of the as-fabricated nanoscale devices but also can play the role of a protective layer, which can partially improve the damage threshold of these plasmonic nanoscale devices.