Broadband 2D phase-gradient metasurface for linearly-polarized waves by suppressing Lorentz resonance of meta-atoms.

Metasurfaces have exhibited versatile capacities of controlling electromagnetic (EM) waves due to the high degree of freedom of designing artificially engineered meta-atoms. For circular polarization (CP), broadband phase gradient metasurfaces (PGMs) can be realized based on P-B geometric phase by rotating meta-atoms; while for linear polarization (LP), realization of broadband phase gradients has to resort to P-B geometric phase during polarization conversion and polarization purity has to be sacrificed for broadband properties. It is still challenging to obtain broadband PGMs for LP waves without polarization conversion. In this paper, we propose the design of 2D PGMs by combining the inherently wideband geometric phases and non-resonant phases of meta-atom, under the philosophy of suppressing Lorentz resonances that usually bring about abrupt phase changes. To this end, an anisotropic meta-atom is devised which can suppress abrupt Lorentz resonances in 2D for both x- and y-polarized waves. For y-polarized waves, the central straight wire is in perpendicular to electric vector Ein of incident waves, Lorentz resonance cannot be excited although the electrical length approaches or even exceeds half a wavelength. For x-polarized waves, the central straight wire is in parallel with Ein, a split gap is opened on the center of the straight wire so as to avoid Lorentz resonance. In this way, the abrupt Lorentz resonances are suppressed in 2D and the wideband geometric phase and the gradual non-resonant phase are left for broadband PGM design. As a proof of concept, a 2D PGM prototype for LP waves was designed, fabricated and measured in microwave regime. Both simulated and measured results show that the PGM can achieve broadband beam deflection for reflected waves for both x- and y-polarized waves in broadband, without changing the LP state. This work provides a broadband route to 2D PGMs for LP waves and can be readily extended to higher frequencies such as terahertz and infrared regimes.

Endoscopic anatomical study of the trans-lateral molar approach to the infratemporal fossa.

BACKGROUND: The infratemporal fossa (ITF) is located deep in the skull base. Recently, the endoscopic transoral approach has enabled maxillofacial surgeons to access the ITF using a less invasive approach compared to the traditional transfacial and endonasal endoscopic approaches. OBJECTIVE: The present study aims to provide maxillofacial surgeons with new data concerning direct endoscopic measurement and precise anatomical topography features of the endoscopic trans-lateral molar approach to ITF by comparing the endoscopic and regional anatomy of ITF. A clinical case receiving the proposed surgical approach is used to determine the feasibility of this technique. METHOD: The anatomical data were obtained by measuring the bone anatomical landmarks and analyzing the CT imaging data using GE's Advance Windows 4.1 software on 25 subjects (50 sides). Morphological pictures of the regional anatomy and endoscopic anatomy were obtained from 6 (12 sides) adult cadaver heads, and the anatomical features were described. The present study reports the management of one case using the proposed surgical approach. RESULTS: The proposed surgical approach clearly revealed neurovascular, muscular, and surgical landmarks in the ITF. The surgical case supports the minimally invasive treatment approach, which could rapidly access the ITF and completely excise benign tumors. CONCLUSION: The anatomical studies and surgical case presentation helps us understand the spatial relationship of surgical landmarks of the surgical approach to the ITF for the treatment of benign lesions in the deep cranial base area.

High-efficiency transparent vortex beam generator based on ultrathin Pancharatnam-Berry metasurfaces.

Vortex beam generators are promising to improve the transmission data rate and enlarge the communication capacity due to the fact that they inherently carry the orbital angular momentum (OAM). However, current available devices are limited because of high profiles and low efficiencies, especially for the transmissive case. Here, we propose a new strategy to design an ultrathin (0.07λ0) transmissive Pancharatnam-Berry (PB) metasurface with nearly unit transmittance. The carefully optimized metasurface integrates an anisotropic crossbar structure with positive permittivity and a holey metallic ring resonator with negative permittivity based on certain criterions placed on both sides of a dielectric substrate, which realize an exact π phase difference due to the control of permittivities at both polarizations. As a proof of concept, a microwave vortex beam generator is designed, fabricated and experimentally characterized. Both measured far-field and near-field characterizations are in excellent agreement with numerical simulations, indicating that our transmissive PB meta-device (operating at 10.6 GHz) exhibits a maximum experimental efficiency of 87%. Our findings can motivate the realizations of high-performance transmissive PB meta-devices with a very low profile or operation at other frequency domains.

Cochlea sparing with a stratified scheme of dose limitation employed in intensity-modulated radiotherapy for nasopharyngeal carcinoma: A dosimetry study.

Hearing loss is 1 of the major complications after radiotherapy in nasopharyngeal carcinoma (NPC) patients, how to minimize dose to cochlea in order to reduce the incidence of sensorineural hearing loss is a critical task. This study is to investigate a stratified scheme of cochlea sparing based on T stage in intensity-modulated radiotherapy. We designed a comparison between 2 plans of cochlea sparing plan (C-Plan) and regular noncochlea sparing plan (R-Plan) from 19 NPC patients with 2, 3, 8, and 6 cases of T1, T2, T3, and T4 stage, respectively. The outcomes showed that target coverage parameters and dose-volume histogram features were of no significant difference, with a significant difference in dose distribution between C-Plan and R-Plan in cochlea and eustachian, e.g., ipsilateral cochlea Dmean 4619.75 ± 1134.09 cGy in C-Plan and 5061.03 ± 1121.09 cGy in R-Plan (p = 0.000), contralateral cochlea Dmean 4386.73 ± 945.14 cGy in C-Plan and 4991.38 ± 961.21 cGy in R-Plan (p = 0.000). Meanwhile, there was no significant difference in dose distribution in spinal cord, brainstem, and other OARs. Our dosimetry study showed cochlea sparing in intensity-modulated radiotherapy for NPC reduced cochlea dose to different extent, so we suggested a stratified scheme of cochlea sparing based on T stage could be a useful and practical tool for both physicists and radiation doctors.

High-efficiency dual-modes vortex beam generator with polarization-dependent transmission and reflection properties.

Vortex beam is believed to be an effective way to extend communication capacity, but available efforts suffer from the issues of complex configurations, fixed operation mode as well as low efficiency. Here, we propose a general strategy to design dual-modes vortex beam generator by using metasurfaces with polarization-dependent transmission and reflection properties. Combining the focusing and vortex functionalities, we design/fabricate a type of compact dual-modes vortex beam generator operating at both reflection/transmission sides of the system. Experimental results demonstrate that the designed metadevice can switch freely and independently between the reflective vortex with topological charge m1 = 2 and transmissive vortex with m2 = 1. Moreover, the metadevice exhibits very high efficiencies of 91% and 85% for the reflective and transmissive case respectively. Our findings open a door for multifunctional metadevices with high performances, which indicate wide applications in modern integration-optics and wireless communication systems.

Polarization-independent broadband meta-surface for bifunctional antenna.

Functional integration is crucial and has become a research interest in recent years; however, available efforts suffer from low efficiency and narrow operating bandwidth. Here, we propose a novel strategy to design bifunctional meta-surface with high efficiency and largely enhanced bandwidth in reflection geometry. For demonstration, we designed and fabricated a bifunctional meta-surface which enables both focusing and anomalous reflection under different polarizations. The working bandwidth is significantly extended by using the dual-resonant three-turn meander-line resonator (TMLR) element which provides an almost consistent phase response within a large frequency interval. For potential applications, we engineered a bifunctional antenna by launching the designed meta-surface with proper feed sources. Numerical and experimental results coincide well, indicating bifunctionalities of high gain pencil-beam radiation (reflectarray) and beam steering radiation with comparable performances. Our results can stimulate the realizations of high-performance meta-surfaces and antenna systems.

Study on effectiveness of gemcitabine, dexamethasone, and cisplatin (GDP) for relapsed or refractory AIDS-related non-Hodgkin's lymphoma.

Non-Hodgkin's lymphoma (NHL) remains the second most common malignant complication in patients with human immunodeficiency virus (HIV) infection. Even though NHL is commonly chemosensitive to primary treatment, failure or relapse still occurs in a large number of patients. We conducted this retrospective study to evaluate the efficacy and safety of gemcitabine, dexamethasone, and cisplatin (GDP) for relapsed or refractory AIDS-related NHL (AIDS-NHL). Forty-eight patients with relapsed or refractory AIDS-NHL were treated with intravenous combination chemotherapy with GDP. The overall objective response rate was 54.1% (95% confidence interval, CI, 40.1-68.3%), with 10 complete responses and 16 partial responses. The 2-year overall survival rate (OS) was 70.8% (95% CI 58.0-83.7%), and the 5-year OS was 41.7% (95% CI 27.7-55.6%). The 2-year progression-free survival rate (PFS) was 37.5% (95% CI 23.8-51.2%), and the 5-year PFS was 25.0% (95% CI 12.8-37.3%). The median progression-free survival was 8.8 months (95% CI 0-20.3 months), and the median overall survival was 40.6 months (95% CI 22.6-58.6 months). Patients with B cell tumors who relapsed but had no B symptoms were clinical stage I/II, had infiltration fewer than two extranodal sites, had CD4⁺ counts >200 cells/µL, and had lactate dehydrogenase (LDH) less than the upper limit of normal benefited from GDP. The level of LDH had a significant impact on the response rate to chemotherapy with GDP (P = 0.015). Myelosuppression was the main side effect; the incidence of grade 3-4 anemia was 8.3%; leukopenia, 37.5%; and thrombocytopenia, 48.3%. Univariate and multivariate analyses were performed to determine variables for OS and PFS. This study confirms that GDP is an effective and safe salvage regimen in relapsed or refractory AIDS-NHL, was associated with modest declines in CD4⁺ lymphocyte counts, and did not promote HIV-1 viral replication.

Etoposide, vincristine, doxorubicin and dexamethasone (EVAD) combination chemotherapy as second-line treatment for advanced AIDS-related Kaposi's sarcoma.

OBJECTIVE: To evaluate through retrospective analysis the efficacy and toxicity of combination chemotherapy with etoposide, vincristine, doxorubin and dexamethasone (EVAD) as second-line therapy in patients with advanced AIDS-related Kaposi's sarcoma (AIDS-KS) after failure of first-line chemotherapy. METHODS: Eighty-eight patients with poor-risk AIDS-KS were treated intravenously with combination chemotherapy with EVAD; etoposide at a dose of 100 mg/m(2) on three consecutive days, vincristine 1.4 mg/m(2) with a maximum single dosage of 2.0 mg on day one, doxorubicin 30 mg/m(2) on day one and dexamethasone 40 mg on three consecutive days, with a three week cycle. All eligible patients had relapsed or progressed after prior two to six cycles of combination chemotherapy with doxorubicin, bleomycin and vincristine (ABV) or bleomycin and vincristine (BV). RESULTS: Assessment of the response of all the patients was made. The overall objective response rate was 59.1% (95% CI 48.83-69.37%), with five complete responses and 47 partial responses. Twenty-six cases of stable disease and 10 of progressive disease were observed in the remaining patients. The median follow-up period was 27 months (range 8-52 months). The median time to progression was 6.80 months (95% CI 2.04-11.56 months), and the median overall survival was 14.24 months (95% CI 10.26-18.22 months). Leucopenia was seen in 92.0% of patients, of which 20 patients had grade 3 and 12 had grade 4. Conclusions Combination chemotherapy with EVAD offers a new, active and safe therapeutic approach for the treatment of advanced AIDS-related KS.

[The clinical characteristics of histiocytic necrotizing lymphadenitis: analysis of 11 cases].

OBJECTIVE: To study the clinical features of histiocytic necrotizing lymphadenitis. METHOD: Eleven patients with histiocytic necrotizing lymphadenitis were collected to analyze the clinical features, pathological features of biopsy lymph nodes, diagnosis and treatment. RESULT: Lymph node swelling of neck and persistent fever were detected in all patients. The leukocyte reduction and swiftness of ESR in serum were detected in most patients. The final diagnosis of histiocytic necrotizing lymphadenitis was confirmed by biopsy investigation of the pathology. The pathological features included distinctive necrosis, loss of lymph node structure, infiltration with histiocytes and lymphocytes, absence of neutrophils. All patients were treated with glucocorticoid for 2 to 4 months. The patients improved significantly and were not recurrence during follow up visit. CONCLUSION: There was no specific clinical manifestation of histiocytic necrotizing lymphadenitis and which easy to misdiagnoses. Diagnosis of histiocytic necrotizing lymphadenitis relies on the pathological examination of enlarged lymph nodes.

[Prevention of allograft vasculopathy by transfection of calcitonin gene-related peptide].

OBJECTIVE: To explore suppression of allograft vasculopathy (AV) by transfer of the calcitonin gene-related peptide (CGRP). METHODS: The descending thoracic aortas from 39 Lewis rats were grafted to the abdominal aortas of 39 F344 rats, and then the recipient rats were randomized into 3 groups: Group A transfected with Ad5-CGRP-EGFP, a gene construct containing sequences from the adenoviral oncoprotein, CGRP, and enhanced green fluorescent protein, Group B, transfected with Ad5-EGFP containing sequences from the adenoviral oncoprotein and enhanced green fluorescent protein, and Group C without transfection. Four and 8 weeks later the abdominal aortas of 6 recipient rats from each were collected respectively. The degree of vascular obstruction was observed by microscopy. Frozen tissue sections were made and the inverted phase contrast fluorescence microscopy was used to observe the green fluorescence showing the expression of CGRP and enhanced green fluorescent protein (EGFP). RT-PCR was used to detect the expression of CGRP. Immunohistochemistry was used to examine the expression of inducible nitric oxide synthase (iNOS) and vascular cell adhesion molecule-1 (VCAM-1). The apoptosis index (AI) was detected by TUNEL method. RESULTS: CGRP expression was positive in both Group A and B 4 weeks later and negative in both groups 8 weeks later. Group A is approximately normal in pathological morphology 4 weeks later. The vascular luminal occlusion score of Group A was lower than Groups B and C 4 weeks later, and significantly higher than that I the same group (P < 0.05), however, still lower than those of Groups B and C 8 weeks later. The AI 4 weeks later of Group A was significantly lower than those of Groups B and group C, however, there was no significance in AI among the 3 groups. Four weeks later the VCAM-1 expression levels in the tunicae intima, media, and adventitia of Group A were all significantly lower than those of Group B C 4 weeks later, however, the iNOS expression level of Group A was only significantly lower than those of Groups B and C in the tunica intima 4 weeks later. CONCLUSION: The expression of CGRP effectively suppresses the development of AV 4 weeks after the operation.