Utilizing Joukowsky transformation in the design of optical fiber for elliptical-to-circular mode conversion.

This study addresses the challenge of enhancing coupling efficiency between optical fibers and elliptical Gaussian beams emitted by semiconductor lasers, particularly in fiber communication systems. We introduce a method for fiber design utilizing the Joukowsky transformation to facilitate efficient mode transformation from elliptical to circular, thereby augmenting the coupling efficiency with both single-mode and multimode fibers. Theoretical analysis and numerical simulations demonstrate that the fiber with a structurally transitional core maintains high-efficiency mode transformation across various lengths, and its structure has been optimized accordingly. Additionally, our investigation reveals the designed fiber's ability to preserve polarization states, which could have significant implications in precision optical applications. The proposed design offers an approach to improving performance in optical communication systems, especially in wavelength-division multiplexing (WDM) transmission systems and fiber lasers.

Dish spliced concentrator with both uniform and focused performance through a variable focal length.

We present a dish spliced concentrator (DSC) featuring hexagonal spherical sub-mirrors of uniform size. The DSC offers advantages over traditional parabolic dish concentrators, including a compact layout, cost-effectiveness, higher concentration ratio, and improved light uniformity. Its versatility allows for both uniform and focused light concentration by adjusting parameters like the focal length of the DSC, making it suitable for concentrating photovoltaic (CPV) and concentrating solar thermal (CST) applications. We design the DSC using three-dimensional (3D) vector rotation theory, implementing ray tracing and transmission characteristic analysis based on three-dimensional vector reflection theory. We establish a simulation model to evaluate the impact of geometric parameters on the DSC's optical performance.

Design of a compact off-axis two-mirror freeform optical antenna for shaping and transmitting an elliptical beam emitted by laser diode.

Elliptical Gaussian beams generated by laser diodes (LDs) often exhibit asymmetrical divergence angle distribution, which limits their practical applications. In this study, we propose what we believe is a novel approach to shape and collimate the elliptical output beam from a LD. The design process involves the construction of two freeform reflective surfaces on a reference circle using a three-dimensional point-by-point iterative method, based on the law of conservation of energy, the vector reflection theory, and Fermat's principle. The output beam's maximum divergence angle is effectively compressed to 3.1579 mrad. The design is compact with a folded optical path and antenna size of 368.8c m 3. This paper presents a comprehensive design and optimization process, along with an in-depth analysis of the system's performance, thereby offering novel insights for emerging optical design practitioners.

Global caustic and phase chirality reversal of the focused vortex beam.

We predict the reversal of the phase chirality before and after the focal plane during propagation based on ray tracing. The interference patterns of a focused vortex beam (FVB) and a plane beam during propagation verify the fact of phase chirality reversal through diffraction theoretical simulations and experiments. Also, we deduce an analytical expression for the caustic based on the ray equation, which effectively represents the change of the hollow light field during propagation. Simulation and experimental results demonstrate the effectiveness of the caustic in describing the variation of the global hollow dark spot radius. Furthermore, based on the caustic results at the focal plane, we customize FVBs with the same dark spot radii but different topological charges. Our research results reveal the characteristics of the light field and phase distribution of the FVB during propagation, which will expand our understanding of the properties of the FVB and provide a reference value for applications such as chiral particle manipulation and topological charge recognition.

Multi-focus composite spiral zone plate to generate focused vortices with the comparable intensity based on genetic algorithm.

In this study, we introduce an optical element, named Multi-focus Composite Spiral Zone Plate (MFCSZP), to generate multi focused vortices with approximately equal intensity along the optical axis. The genetic algorithm (GA) is used to optimize the parameters of the MFCSZP, which avoids manual parameter adjustment and improves computational efficiency. We analyze the focusing properties of the constructed MFCSZP theoretically and experimentally. The results provide evidence for its capability to generate multiple focused vortices with comparable peak intensities verified through experiment. This work shows the powerful ability of intelligent algorithms in the optimization of complex optical elements. The proposed optical element showcases potential applications within research areas of optical trapping and laser machining.

The characteristics and alteration of peripheral immune function in patients with multiple system atrophy.

Objective: Multiple system atrophy (MSA) is a degenerative disease. Immune dysfunction found to play a crucial role in the pathogenesis of this disease in the literature, while the characteristics of peripheral immune function remain unclear. This study aimed to investigate the characteristics and alterations of peripheral immune function in patients with MSA. Methods: A case-control study was conducted between January 2021 to December 2022 at SanBo Brain Hospital, Capital Medical University, Beijing, China. A total of 74 participants were recruited, including 47 MSA patients and 27 non-MSA participants. Peripheral blood samples were collected from each participant. A total of 29 types of immune cells were measured using the flow cytometry analysis technology. Single-factor analysis and multiple-factor analysis (multiple linear regression models) were performed to determine the differences and risk factors in immune cells between the MSA and non-MSA groups. Results: Alterations of the count or percentage of CD19+ B lymphocytes and CD3-CD56+ B lymphocytes in MSA patients were found in this study. The reductions of the count and percentage of CD19+ B lymphocytes were still robust after adjusting for variables of age, gender, body mass index, albumin, and hemoglobin. Furthermore, the reductions in the count and percentage of CD19+ B lymphocytes in the MSA patients were more significant in women and individuals aged 60 years old or above than in the non-MSA participants. Conclusion: Our findings suggested that MSA patients may be influenced by B lymphocytes, particularly CD19+ cells. Therefore, the reductions in immune cells should be considered in the diagnosis and treatment of MSA. Further studies are warranted to confirm and expand upon these findings.

Cyclobutanedicarboxylate Metal-Organic Frameworks as a Platform for Dramatic Amplification of Pore Partition Effect.

Ultrafine tuning of MOF structures at subangstrom or picometer levels can help improve separation selectivity for gases with subtle differences. However, for MOFs with a large enough pore size, the effect from ultrafine tuning on sorption can be muted. Here we show an integrative strategy that couples extreme pore compression with ultrafine pore tuning. This strategy is made possible by unique combination of two features of the partitioned acs (pacs) platform: multimodular framework and exceptional tolerance toward isoreticular replacement. Specifically, we use one module (ligand 1, L1) to shrink the pore size to an extreme minimum on pacs. A compression ratio of about 30% was achieved (based on the unit cell c/a ratio) from prototypical 1,4-benzenedicarboxylate-pacs to trans-1,3-cyclobutanedicarboxylate-pacs. This is followed by using another module (ligand 2, L2) for ultrafine pore tuning (<3% compression). This L1-L2 strategy increases the C2H2/CO2 selectivity from 2.6 to 20.8 and gives rise to an excellent experimental breakthrough performance. As the shortest cyclic dicarboxylate that mimics p-benzene-based moieties using a bioisosteric (BIS) strategy on pacs, trans-1,3-cyclobutanedicarboxylate offers new opportunities in MOF chemistry.

Tailoring the catalytic activity and selectivity on CO2 to C1 products by the synergistic effect of reactive molecules: A DFT study.

The conversion of CO2 to CO is one of the crucial pathways in the carbon dioxide reduction reaction (CO2RR). Iron and nitrogen co-doped carbon matrix (FeN4) is a promising catalyst for converting CO2to CO with excellent activity and selectivity. However, the reactive mechanism of CO2RR on the FeN4 catalyst is not fully unveiled. For example, it is still evasive that the obtained C1 product is methanol and/or methane instead of CO in some cases. Herein, DFT calculation is conducted to unravel the effect from both solvent molecules and intermediates as axial groups on the selectivity of C1 products in CO2RR using FeN4 catalyts. Calculation results demonstrate that the FeN4(H), FeN4(OH), FeN4(COOH), and FeN4(CO) configurations are not only beneficial to the removal of CO, but also effectively suppress the hydrogen evolution reaction, whereas the FeN4, FeN4(CO2) and FeN4(H2O) configurations are inclined to produce CH3OH and/or CH4. The mechanism studied in this work provides an inspiration of optimizing the selectivity of C1 products in CO2RR from the perspective of regulating solvent molecules and intermediates as axial groups on FeN4.

Multi-Modular Design of Stable Pore-Space-Partitioned Metal-Organic Frameworks for Gas Separation Applications.

Pore space partition (PSP) is an effective materials design method for developing high-performance small-pore materials for storage and separation of gas molecules. The continued success of PSP depends on broad availability and judicious choice of pore-partition ligands and better understanding of each structural module on stability and sorption properties. Here, by using substructural bioisosteric strategy (sub-BIS), a dramatic expansion of pore-partitioned materials is targeted by using ditopic dipyridyl ligands with non-aromatic cores or extenders, as well as by expanding heterometallic clusters to uncommon nickel-vanadium and nickel-indium clusters rarely known before in porous materials. The dual-module iterative refinement of pore-partition ligands and trimers leads to remarkable enhancement of chemical stability and porosity. Here a family of 23 pore-partitioned materials synthesized from five pore-partition ligands and seven types of trimeric clusters is reported. New materials with such compositionally and structurally diverse framework modules reveal key factors that dictate stability, porosity, and gas separation properties. Among these, materials based on heterometallic vanadium-nickel trimeric clusters give rise to the highest long-term hydrolytic stability and remarkable uptake capacity for CO2 , C2 H2 /C2 H4 /C2 H6 , and C3 H6 /C3 H8 hydrocarbon gases. The breakthrough experiment shows the potential application of new materials for separating gas mixtures such as C2 H2 /CO2 .

Set of mathematical models for Bessel-Gauss beams coupling into the parabolic-index fiber under the influence of atmospheric turbulence and random jitter.

The expression of efficiency for Bessel-Gauss (BG) beams coupling into the parabolic fibers (PF) after passing through the Cassegrain antenna system is first derived. The effects of atmospheric turbulence and random jitter of the coupling lens on the efficiency are also taken into account to improve the practical applicability of our model. This article use a BG beam with a wavelength of 1550 mm and fiber with a core radius RF of 50 µm and a relative refractive index difference ζ of 0.01 for simulation testing. The optimal parameters of the antenna system are determined: the radius of the primary mirror and the secondary mirror is 8.33 cm and 1.25 cm, respectively. The coupling efficiency of BG beams of different orders reaches above 94% simultaneously when the lens's focal length is 7.8 cm. After taking into account the transmission efficiency of the antenna system, the system's total efficiency for BG beams of different orders averages 76.33%, when the transmission distance is 1 km. The results show that the same degree of turbulence and random jitter have different influences on the coupling efficiency of BG beams of different orders, and lower-order BG beams have better resistance to turbulence and jitter during propagation and coupling. Moreover, the effect of the guided mode field on the coupling efficiency and the resistance to turbulence varies for different values of mode radial index in the fiber p. The guided mode with p = 0 not only enables the BG beams of different orders to achieve the highest transmission efficiency in the coupling system almost simultaneously but also the random jitter and turbulence have less influence on the coupling efficiency of this mode. It means that the BG beams can have higher efficiency when coupled to the mode with p = 0 after long-distance transmission. This property of the fiber mode at p = 0 provides conditions for the simultaneous propagation of multiple BG beams in a parabolic fiber, which provides a theoretical basis for higher transmission capacity. This research work provides a theoretical model for the theoretical study of vortex beams and optical communication, which is beneficial for the design and application of vortex beams and has instructive meaning for practical engineering design.

Simultaneous Control of Flexibility and Rigidity in Pore-Space-Partitioned Metal-Organic Frameworks.

Flexi-MOFs are typically limited to low-connected (<9) frameworks. Here we report a platform-wide approach capable of creating a family of high-connected materials (collectively called CPM-220) that integrate exceptional framework flexibility with high rigidity. We show that the multi-module nature of the pore-space-partitioned pacs (partitioned acs net) platform allows us to introduce flexibility as well as to simultaneously impose high rigidity in a tunable module-specific fashion. The inter-modular synergy has remarkable macro-morphological and sub-nanometer structural impacts. A prominent manifestation at both length scales is the retention of X-ray-quality single crystallinity despite huge hexagonal c-axial contraction (≈ 30%) and harsh sample treatment such as degassing and sorption cycles. CPM-220 sets multiple precedents and benchmarks on the pacs platform in both structural and sorption properties. They possess exceptionally high benzene/cyclohexane selectivity, unusual C3H6 and C3H8 isotherms, and promising separation performance for small gas molecules such as C2H2/CO2.

Design of a compact optical antenna system with high transmission efficiency utilizing a ring-like VCSEL array.

Vertical cavity surface-emitting lasers (VCSELs) with gigahertz bandwidth and good beam quality possess great potential for multi-wavelength free-space optical communication. In this Letter, a compact optical antenna system utilizing a ring-like VCSEL array that can realize the parallel transmission of multi-channel and multi-wavelength collimated laser beams and has the advantages of aberration elimination and high transmission efficiency is proposed. Ten different signals can be transmitted simultaneously, greatly increasing the channel capacity. Based on the vector theory of reflection, ray tracing and the performance of the proposed optical antenna system are demonstrated. This design method has a certain reference value for designing complex optical communication systems with high transmission efficiency.

Pancreatic neuroendocrine tumor detected by technetium-99m methoxy-2-isobutylisonitrile single photon emission computed tomography/computed tomography: A case report.

BACKGROUND: Pancreatic neuroendocrine tumors (NETs) account for about 1%-2% of pancreatic tumors and about 8% of all NETs. Computed tomography (CT), magnetic resonance imaging, and endoscopic ultrasound are common imaging modalities for the diagnosis of pancreatic NETs. Furthermore, somatostatin receptor imaging is of great value for diagnosing pancreatic NETs. Herein, we report the efficacy of technetium-99m methoxy-2-isobutylisonitrile (99mTc-MIBI) single photon emission CT (SPECT)/CT for detecting pancreatic NETs. CASE SUMMARY: A 57-year-old woman presented to our hospital with a 1-d history of persistent upper abdominal distending pain. The distending pain in the upper abdomen was aggravated after eating, with nausea and retching. Routine blood test results showed a high neutrophil percentage, low leukomonocyte and monocyte percentages, and low leukomonocyte and eosinophil counts. Amylase, liver and kidney function, and tumor markers alpha-fetoprotein, carcinoembryonic antigen, and cancer antigen (CA) 125, CA72-4, CA19-9, and CA153 were normal. Abdominal CT showed a mass, with multiple calcifications between the pancreas and the spleen. The boundary between the mass and the pancreas and spleen was poorly defined. Contrast-enhanced CT revealed that the upper abdominal mass was unevenly and gradually enhanced. 99mTc-MIBI SPECT/CT revealed that a focal radioactive concentration, with mild radioactive concentration extending into the upper abdominal mass, was present at the pancreatic body and tail. The 99mTc-MIBI SPECT/CT manifestations were consistent with the final pathological diagnosis of pancreatic NET. CONCLUSION: 99mTc-MIBI SPECT/CT appears to be a valuable tool for detecting pancreatic NETs.

Transcutaneous Auricular Vagus Nerve Stimulation (ta-VNS) for Treatment of Drug-Resistant Epilepsy: A Randomized, Double-Blind Clinical Trial.

This study explored the efficacy and safety of transcutaneous auricular vagus nerve stimulation (ta-VNS) in patients with epilepsy. A total of 150 patients were randomly divided into active stimulation group and control group. At baseline and 4, 12, and 20 weeks of stimulation, demographic information, seizure frequency, and adverse events were recorded; at 20 weeks, the patients underwent assessment of quality of life, Hamilton Anxiety and Depression scale, MINI suicide scale, and MoCA scale. Seizure frequency was determined according to the patient's seizure diary. Seizure frequency reduction > 50% was considered effective. During our study, the antiepileptic drugs were maintained at a constant level in all subjects. At 20 weeks, the responder rate was significantly higher in active group than in control group. The relative reduction of seizure frequency in the active group was significantly higher than that in the control group at 20 weeks. Additionally, no significant differences were shown in QOL, HAMA, HAMD, MINI, and MoCA score at 20 weeks. The main adverse events were pain, sleep disturbance, flu-like symptoms, and local skin discomfort. No severe adverse events were reported in active and control group. There were no significant differences in adverse events and severe adverse events between the two groups. The present study showed that ta-VNS is an effective and safe therapy for epilepsy. Furthermore, the benefit in QOL, mood, and cognitive state of ta-VNS needs further validation in the future study although no significant improvement was shown in this study.

Concurrent Enhancement of Acetylene Uptake Capacity and Selectivity by Progressive Core Expansion and Extra-Framework Anions in Pore-Space-Partitioned Metal-Organic Frameworks.

A multi-stage core-expansion method is proposed here as one component of the integrative binding-site/extender/core-expansion (BEC) strategy. The conceptual deconstruction of the partitioning ligand into three editable parts draws our focus onto progressive core expansion and allows the optimization of both acetylene uptake and selectivity. The effectiveness of this strategy is shown through a family of eight cationic pore-partitioned materials containing three different partitioning ligands and various counter anions. The optimized structure, Co3 -cpt-tph-Cl (Hcpt=4-(p-carboxyphenyl)-1,2,4-triazole, H-tph=(2,5,8-tri-(4-pyridyl)-1,3,4,6,7,9-hexaazaphenalene) with the largest surface area and highest C2 H2 uptake capacity (200 cm3 /g at 298 K), also exhibits (desirably) the lowest CO2 uptake and hence the highest C2 H2 /CO2 selectivity. The successful boost in both C2 H2 capacity and IAST selectivity allows Co3 -cpt-tph-Cl to rank among the best crystalline porous materials, ionic MOFs in particular, for C2 H2 uptake and C2 H2 /CO2 experimental breakthrough separation.

Developing Water-Stable Pore-Partitioned Metal-Organic Frameworks with Multi-Level Symmetry for High-Performance Sorption Applications.

A new perspective is proposed in the design of pore-space-partitioned MOFs that is focused on ligand symmetry properties sub-divided here into three hierarchical levels: 1) overall ligand, 2) ligand substructure such as backbone or core, and 3) the substituent groups. Different combinations of the above symmetry properties exist. Given the close correlation between nature of chemical moiety and its symmetry, such a unique perspective into ligand symmetry and sub-symmetry in MOF design translates into the influences on MOF properties. Five new MOFs have been prepared that exhibit excellent hydrothermal stability and high-performance adsorption properties with potential applications such as C3 H6 /C2 H4 and C2 H2 /CO2 selective adsorption. The combination of high stability with high benzene/cyclohexane selectivity of ≈13.7 is also of particular interest.

Cerebral Ischemia/Reperfusion Injury and Pharmacologic Preconditioning as a Means to Reduce Stroke-induced Inflammation and Damage.

Stroke is one of the leading causes of death and long-term serious disability. Current therapeutic strategy is limited to thrombolytic agents, consequently, boosting endogenous neuroprotective mechanisms of the brain to protect itself against harmful stimuli and restore from damages are widely studied. Preconditioned brain to tolerate cerebral ischemia/reperfusion injury could be initiated by several different pharmacological and mechanical strategies, such as ischemic preconditioning, ethanol pharmacological preconditioning and other pre- and post-conditions, such as remote ischemic preconditioning and exercise preconditioning. In this article, we will discuss the major mechanism of ischemia/reperfusion injury and provide an overview of preconditioning in all its various forms, describe the underlying mechanisms and review the recent clinical application of this emerging neuroprotective strategy.

Mapping the neural circuits responding to deep brain stimulation of the anterior nucleus of the thalamus in the rat brain.

Clinical studies have demonstrated that deep brain stimulation of the anterior nucleus of the thalamus (ANT) is a safe and effective treatment for focal epilepsy and drug-resistant epilepsy. However, the mechanism of action of ANT deep brain stimulation, especially in terms of neuromodulatory circuits, is not fully understood. In this study, we evaluated the anatomical and functional connectivity of the ANT in rats. For anatomical connectivity, herpes simplex virus (HSV) and pseudorabies virus (PRV; Bartha stain) were focally injected into the ANT of rats to label the connected brain structures in the retrograde and anterograde directions, respectively. For functional connectivity, we used c-Fos mapping in conjunction with electrical stimulation of the ANT to map the brain structures functionally connected to the ANT. Circuit connectivity mapping revealed that the ANT was connected to the hippocampus, the nucleus accumbens, the dorsal part of the lateral septal nucleus (LSD), the amygdala, the secondary motor cortex (M2), the cingulate cortex, the substantia nigra, the hypothalamus, and other regions. The ipsilateral connections were stronger than the contralateral connections. Deep brain stimulation of the ANT resulted in c-fos expression in the cortex, hippocampus, amygdala, striatum and hypothalamus, with the strongest activation in the hippocampus. These results suggest that the ANT has a wide range of structural and functional connections, which may underlie the effectiveness of deep brain stimulation in treating epilepsy. DATA AVAILABILITY STATEMENT: The datasets generated for this study are available on request to the corresponding author.

In Situ Synthesized Homochiral Spiroborate Ester Metal-Organic Framework with Mono-, Di-, and Trivalent Cations.

We report here a one-step method for synthesizing multi-component and in-situ-formed homochiral spiroborate-ester-based metal-organic framework CPM-B1. This unique material successfully integrates COF fragment spiroborate ester within the MOF and simultaneously incorporate homochirality and helicity. In addition, CPM-B1 is a rare example of framework materials that results from the cooperative assembly of three charge-complementary cations: +1 (lithium), +2 (cobalt), and +3 (boron). The sophistication of the co-assembly is further highlighted by the three structural roles of lithium ions. This unique structure contributes to its multi-functional properties such as ionic conductivity and catalytic activity for oxygen reduction reaction (by CPM-B1 carbonized material) and provides a new path to develop MOF materials with complex secondary building units and multi-functional applications.

Fiber coupling efficiency of a Bessel-Gaussian beam received by a Cassegrain antenna under atmospheric turbulence.

A coupling efficiency calculation method for a Bessel-Gaussian (BG) beam in a free space optical communication system received by a parabolic Cassegrain antenna and coupled into a few-mode fiber is proposed. The system of the antenna and the coupling lens is approximate to a ring-shaped lens. The effect of the antenna in the coupling system is analyzed, and maximum coupling efficiency is increased by 76.25% on average by applying the antenna. With the application of the antenna, the configurations to generate the maximum point of coupling efficiency among BG beams of different topological charges are restricted to being almost the same, which is useful for the simultaneous propagation of multiple BG beams. The effects of radial displacement and atmospheric turbulence on coupling efficiency are researched as well. Coupling efficiency becomes more sensitive to radial displacement, while the influence of turbulence on coupling efficiency remains almost the same after applying the antenna. Our calculation method has an average absolute error of only 0.6625% while increasing the calculation speed greatly, which is practical for further studies of vortex beams.