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.

Ring focus reflector design for topological charge multiplexing based on a perfect vortex beam.

A ring focus reflector is proposed for transmitting a perfect vortex (PV) beam, and the transmission characteristics of the PV beam with different topological charges in free space after passing through the reflector are studied. The reflector parameters can be determined by fitting the structural formula, and PV beams of different orders transmit with small spot sizes at the same time. The transmission trajectory calculated by the diffraction formula is consistent with the ray tracing results. The research results show that the reflector can achieve a high level of transmission efficiency of beams with different topological charges, which is conducive to the multiplexing of PV beams.

Design of a high-Q dark hollow beam cavity based on a one-dimensional topological photonic crystal.

Dark hollow beams (DHBs) possess great potential for material processing, holography, and vortex beams, and thus designing a high-Q DHB cavity is significant for these applications. In this Letter, a method of designing and optimizing a high-Q DHB cavity based on a one-dimensional topological photonic crystal (TPhC) is proposed. Furthermore, how the structural parameters control the performance of the cavity is analyzed with the help of finite-element-method (FEM) simulation. According to the simulation results, the Q factor of the designed cavity can reach the order of 105 with only 19 periods of layers. It is critical to mention that, although increasing the layers can improve the average Q of the cavity, it will cause serious fluctuation of both the Q factor and the divergence angle of the output beam. The design method proposed in this Letter may not only help designers of future DHB lasers but also promote the applications of DHBs in various fields.

Optimization method for low-loss single-mode bending negative curvature anti-resonant hollow-core fiber designed by mode modification.

A method of designing negative curvature anti-resonant hollow-core fibers (NC-AR-HCFs) with bending resistance is proposed, by which the fundamental mode (FM) and higher-order mode (HOM) can be adjusted. An asymmetric double-ring negative curvature hollow-core fiber (ADR-NC-HCF) is proposed to verify the method. The ADR-NC-HCF achieves the FM loss of 0.8 dB/km at 1550 nm under the bending radius of 20 mm. The coupling relation between the modes in ADR-NC-HCFs is analyzed revealing the physical principle of the design method. Based on the principle, the fiber can be directionally optimized to achieve a lower loss of the FM or higher-order mode extinction ratio.

Fast analysis of selected compounds in inhaled and exhaled vapor phase of cigarette smoke to evaluate components retained in the upper respiratory tract.

RATIONALE: The aim of this work is to use a new design of online sampling photoionization mass spectrometer to analyze chemical ingredients in inhaled and exhaled cigarette smoke directly without separation. METHODS: Based on vacuum ultraviolet photoionization time-of-flight mass spectrometry (VUV-PI-TOFMS) and a sampling system, a newly developed rapid online sampling design approach was used for the upper respiratory tract retention study of gaseous mainstream cigarette smoke components during smoking. The cigarette smoke inhaled or exhaled by seven subjects who displayed three different smoking patterns was directly sampled into a vacuum chamber, photoionized, and analyzed using TOFMS. RESULTS: Fourteen species, comprising aldehydes, ketones, phenol, methanethiol, nitrogen-containing heterocyclic compounds and unsaturated hydrocarbons, were identified in the cigarette smoke obtained from Virginia-type cigarettes. The upper respiratory tract results for these compounds were similar for smokers with the three different smoking patterns: aldehyde and ketone constituents had a high retention level of more than 60%; phenol, methanethiol, and nitrogen-containing heterocyclic compounds were retained at between 30% and 70%; and the retention of unsaturated hydrocarbons was about 20%-60%. The retention trend of the same smoke components in Virginia-type cigarettes by subjects from the three smoking patterns (A, B, and C) was consistent, and the retentions all increased with increased smoking age (A < B < C). CONCLUSIONS: This is the first report of a new online sampling design approach to the study of cigarette smoke components in inhaled and exhaled breath, to evaluate components retained in the upper respiratory tract by subjects with different smoking patterns. This method has good repeatability, and the results indicated that this is a very promising tool for the study of the retention of cigarette smoke constituents.

Polyethylenimine-based nanovector grafted with mannitol moieties to achieve effective gene delivery and transfection.

Polyethylenimine (PEI), a kind of cationic non-viral gene delivery vector, is capable of stable and efficient transgene expression for gene delivery. However, low transfection efficiency in vivo along with high toxicity limited the further application of gene therapy in the clinic. To enhance gene transfection performance and reduce cytotoxicity of polyethylenimine, branched polyethylenimine-derived cationic polymers BPEI25 k-man-S/L/M/H with different grafting degree with mannitol moieties were prepared and the transfection efficiency was evaluated. Among them, BPEI25 k-man-L showed the best transfection efficiency, lower toxicity, and significantly enhanced long-term systemic transgene expression for 96 h in vivo even at a single-dose administration. The results of cellular uptake mechanism and western-blot experiments revealed that the mannitol modification of BPEI25 k induced and up-regulated the phosphorylation of caveolin-1 and thus enhanced the caveolae-mediated cellular uptake. This class of gene delivery system highlights a paradigmatic approach for the development of novel and safe non-viral vectors for gene therapy.

Construction of α-Cyclodextrin-Based Stimuli-Responsive Gene Delivery Nanovectors: In Vitro, Ex Vivo, and In Vivo Investigations.

Stimuli-responsive materials are promising paradigm applied to construct diagnostic and therapeutic intracellular controlled release vectors, while highlighting many challenges and opportunities. In this paper, six α-cyclodextrin-based supramolecular nanovectors were constructed and the efficacy of amine groups, stimuli-responsive profiles and endocytic mechanisms were investigated. The results indicated that the designed supermolecules can compact DNA to form stable complexes and display low cytotoxicity. Among them, PRPEI-2 with suitable PEI amine group exhibited enhanced transfecting performance, high dilution stability, nice serum compatibility, and good acid-responsive profiles to enable endosome escape, significantly higher than commercially available transfecting agent PEI25000, the most effective vector studied to date. The endocytic uptake mechanisms involved in the transfection was mainly through clathrin-mediated pathway, which is closely associated with and can be improved by endosome escape. Moreover, PRPEI-2/DNA polyplex can be effectively expressed in vivo even after 48 h via only single tail-vein injection, and the gene expression and main tissue distribution appeared in the testis, liver, brain and spleen. These excellent characteristics demonstrated that the supramolecular PRPEI-2 represents an excellent prospect as stimuli-responsive nanovectors for gene diagnosis and therapy.

Enhancing performance of Ag-ZnO-Ag UV photodetector by piezo-phototronic effect.

In this work, an ultraviolet (UV) photodetector based on a ZnO nanowires (NWs) array with metal-semiconductor-metal Schottky junction structure was successfully fabricated on a flexible polyester fibre substrate by a low-temperature hydrothermal method. Subjected to a 0.2% tensile strain at -1 V, the I light and sensitivity of the as-prepared UV photodetector are lifted by 82% and 130%, respectively. Furthermore, the response speed and recovery speed are significantly raised under the same tensile strain. The working principle can be explained as that the Schottky barrier height (SBH) is effectively improved by the negative strain-induced polarization at the metal-ZnO interface which is favorable for the separation of photogenerated electron-hole pairs. This work not only provides a facile and promising means to optimize the performance of a ZnO based MSM photodetector by applying a tensile strain but also opens up the way for fabrication and integration of ZnO photodetectors on flexible polyester fiber substrates.

Wearable triboelectric nanogenerators based on hybridized triboelectric modes for harvesting mechanical energy.

In this paper, we demonstrate a newly designed hybridized triboelectric nanogenerator (TENG) fabric incorporating multiple working modes, which can effectively harvest ambient mechanical energy for conversion into electric power by working in a hybridization of a contact-separation mode, a sliding mode and a freestanding triboelectric layer mode. The power generation of each mode of the TENG fabric was systematically investigated and compared along different directions, under different frequencies and at different locations. Owing to the advanced structural design, the as-fabricated TENG fabric could be switched between multiple working modes according to its real working situation. High output voltage and current of about 140 V and 0.6 µA, respectively, were obtained from a larger size of TENG fabric, which could be used to light up 120 LEDs in series. Compared to the previously reported TENGs, such a hybridized TENG fabric based on hybridized modes has much better adaptability for harvesting energy (such as human walking, running, and other human motion) in different directions. This work presents the promising potential of hybridized TENG fabric for power generation and self-powered wearable devices.

The light-induced pyro-phototronic effect improving a ZnO/NiO/Si heterojunction photodetector for selectively detecting ultraviolet or visible illumination.

In this work, we fabricate a ZnO/NiO/Si heterojunction photodetector, which successfully realizes selective detection of UV or visible light in a single photodetector. In addition, the pyro-phototronic effect has been confirmed as an effective approach for enhancing the performance of photodetectors based on ZnO. The pyro-phototronic effect is carefully studied by comparing with a ZnO/Si heterojunction photodetector under UV and visible illumination at different bias voltages. To enhance the photodetector's wavelength selectivity, the parameters and structure are further optimized for the ZnO/NiO/SiO2/Si heterojunction photodetector. The newly designed photodetector may be used to selectively detect and distinguish UV and visible illumination in a single photodetector.

Enhanced gene transfection performance and biocompatibility of polyethylenimine through pseudopolyrotaxane formation with α-cyclodextrin.

Polyethylenimine (PEI), a commercially available gene transfection reagent, is a promising nonviral vector due to its inherent ability to efficiently condense genetic materials and its successful transfection performance in vitro. However, its low transfection efficiency in vivo, along with its high cytotoxicity, limit any further applications in gene therapy. To enhance the gene transfection performance and reduce the cytotoxicity of linear polyethylenimine, pseudopolyrotaxane PEI25k/CD and the polyrotaxanes PEI25k/CD-PA and PEI25k/CD-PB were prepared and their transfection efficiencies were then evaluated. The pseudopolyrotaxane PEI25k/CD exhibited better transfection efficiency and lower cytotoxicity than the transfection reagent linear PEI25k, even in the presence of serum. It also showed a remarkably higher cell viability, similar DNA protecting capability, and better DNA decondensation and release ability, and could be useful for the development of novel and safe nonviral gene delivery vectors for gene therapy.

Flexible piezoelectric nanogenerators based on ZnO nanorods grown on common paper substrates.

Nanogenerators capable of harvesting energy from environmental mechanical energy are attractive for many applications. In this paper, we present a simple, low-cost approach to convert low-frequency mechanical energy into electric power using piezoelectric ZnO nanorods grown on a common paper substrate. This energy conversion device has ultrahigh flexibility and piezoelectric sensitivity and can produce an output voltage of up to 10 mV and an output current of about 10 nA. It is demonstrated that the device's electric output behavior can be optionally changed between four types of mode simply by controlling the straining rate. Furthermore, it is also shown that the electric output can be enhanced by scaling the size of the device. This energy-harvesting technology provides a simple and cost-effective platform to capture low-frequency mechanical energy, such as body movements, for practical applications.

Investigation of dry eye disease and analysis of the pathogenic factors in patients after cataract surgery.

PURPOSE: To study dry eye and analyze pathogenic factors in patients after cataract surgery. METHODS: A total of 37 patients (50 eyes) were studied by using a 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ25) and Ocular Surface Disease Index (OSDI) 3 days before and 1 week, 1 month, and 3 months after cataract surgery. Slit-lamp microscope examination, cornea and conjunctiva fluorescein staining, tear breakup time (BUT), Schirmer test I (STI), and impression cytology (IC) were carried out at the same time. Cytologic specimens for IC were obtained from the upper lid-covered region, explosive region, and lower lid-covered region of the globe conjunctiva. The average density of goblet cells on these 3 regions was measured, and the pathogenic factors of dry eye after cataract surgery were analyzed. RESULTS: After cataract surgery, the incidence of dry eye increased dramatically; NEI-VFQ25 and OSDI indicated that most patients developed this symptom after surgery. The lacrimal river line became narrow, and BUT and STI decreased in patients after cataract surgery. IC suggested the presence of serious squamous metaplasia in the epithelial layer of the globe conjunctiva, especially the lower lid region. CONCLUSIONS: Dry eye can develop or deteriorate after cataract surgery if not treated in time. Misuse of eyedrops is one of the major pathogenic factors that causes dry eye after cataract surgery. Eyedrops should be carefully administered before and after cataract surgery to avoid or reduce the occurrence of dry eye postoperatively.

[Clinical observation of dry eye in patients before and after cataract surgery].

OBJECTIVE: To investigate dry eye in patients before and after cataract surgery. METHODS: 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ25) and Ocular Surface Disease Index (OSDI) were used for the study in 37 patients (50 eyes) 3 days before cataract surgery and repeated after surgery 1 week, 1 month and 3 months. Slit lamp microscope examination, cornea and conjunctiva fluorescein staining, tear break-up time (BUT), Schirmer test I (STI), impression cytology (IC) were carried out at the same time. RESULTS: After cataract surgery, the incidence of dry eye increased dramatically. Tear river was narrowed, BUT and STI were decreased and shorted in patients after cataract surgery. IC examination showed there was serious squamous metaplasia in epithelial layer of conjunctiva. NEI-VFQ25 was increased from 27.66 +/- 22.08 (before cataract surgery) to 74.69 +/- 11.67 (3 months after cataract surgery). All items of OSDI were remarkable increased, ocular surface abnormal was increased from 2.60 +/- 2.91 (before cataract surgery) to 12.66 +/- 11.40 (3 months after cataract surgery) and environmental trigger was increased from 3.57 +/- 2.67 (before cataract surgery) to 11.40 +/- 10.24 (3 months after cataract surgery). CONCLUSION: Dry eye can be induced or deteriorated after cataract surgery, if it can not be treated on time.