Optimized helical intermedium-period fiber grating for breathing monitoring.

The investigation into the spectral properties and refractive index (RI) sensitivities at low RI region of helical intermedium-period fiber gratings (HIPFGs) with varied periods ranging from 10-48 µm is presented in detail for the first time. The structure of HIPFG is optimized for RI sensing in the RI range of 1.3-1.33 by comparing the optical properties of HIPFGs with different grating periods. The HIPFG with optimized structure is demonstrated to have a high average sensitivity of 302.5 nm/RIU in the RI ranging from 1.3 to 1.33, which is two orders more elevated than the traditional long-period fiber gratings. The improved HIPFG is also experimentally applied to breath monitoring in different states. Normal breath, slow breath, fast breath, and unhealthy breath are distinguished based on breathing rate, intensity, and time of exhalation and inhalation. The fastest response time is determined to be 10 ms. The results demonstrate that the optical fiber's sensitivity in the low RI region can be increased by shortening its period, offering a special strategy for improving detection performance of HIPFGs. By verifying its performance in breathing monitoring, it is proved that the optimized HIPFG sensor has the great potential to expand medical applications.

Structural and signaling mechanisms of TAAR1 enabled preferential agonist design.

Trace amine-associated receptor 1 (TAAR1) senses a spectrum of endogenous amine-containing metabolites (EAMs) to mediate diverse psychological functions and is useful for schizophrenia treatment without the side effects of catalepsy. Here, we systematically profiled the signaling properties of TAAR1 activation and present nine structures of TAAR1-Gs/Gq in complex with EAMs, clinical drugs, and synthetic compounds. These structures not only revealed the primary amine recognition pocket (PARP) harboring the conserved acidic D3.32 for conserved amine recognition and "twin" toggle switch for receptor activation but also elucidated that targeting specific residues in the second binding pocket (SBP) allowed modulation of signaling preference. In addition to traditional drug-induced Gs signaling, Gq activation by EAM or synthetic compounds is beneficial to schizophrenia treatment. Our results provided a structural and signaling framework for molecular recognition by TAAR1, which afforded structural templates and signal clues for TAAR1-targeted candidate compounds design.

Ampere force fiber optic magnetic field sensor using a Fabry-Perot interferometer.

The paper presents a novel fiber-optic vector magnetic field sensor using a Fabry-Perot interferometer, which consists of an optical fiber end face and a graphene/Au membrane suspended on the ceramic ferrule end face. A pair of gold electrodes are fabricated on the ceramic ferrule by femtosecond laser to transmit electrical current to the membrane. Ampere force is generated when an electrical current flows through the membrane in a perpendicular magnetic field. The change in Ampere force causes a shift in the resonance wavelength in the spectrum. In the magnetic field intensity range of 0 ∼ 180 mT and 0 ∼ -180 mT, the as-fabricated sensor exhibits magnetic field sensitivity of 5.71 pm/mT and 8.07 pm/mT. The proposed sensor has great potential application in weak magnetic field measurements due to its compact structure, cost-effectiveness, ease to manufacture, and good sensing performance.

Nano-Optomechanical Resonators Based on Suspended Graphene for Thermal Stress Sensing.

Nanomechanical resonators made from suspended graphene combine the properties of ultracompactness and ultrahigh detection sensitivity, making them interesting devices for sensing applications. However, nanomechanical systems can be affected by membrane stress. The present work developed an optomechanical resonator for thermal stress sensing. The proposed resonator consists of a section of hollow core fiber (HCF) and a trampoline graphene-Au membrane. An all-optical system that integrated optical excitation and optical detection was applied. Then, the resonance frequency of the resonator was obtained through this all-optical system. In addition, this system and the resonator were used to detect the membrane's built-in stress, which depended on the ambient temperature, by monitoring the resonance frequency shift. The results verified that the temperature-induced thermal effect had a significant impact on membrane stress. Temperature sensitivities of 2.2646 kHz/°C and 2.3212 kHz/°C were obtained when the temperature rose and fell, respectively. As such, we believe that this device will be beneficial for the quality monitoring of graphene mechanical resonators.

High-Sensitivity Optical Fiber-Based Glucose Sensor Using Helical Intermediate-Period Fiber Grating.

An all-fiber glucose sensor is proposed and demonstrated based on a helical intermediate-period fiber grating (HIPFG) produced by using a hydrogen/oxygen flame heating method. The HIPFG, with a grating length of 1.7 cm and a period of 35 µm, presents four sets of double dips with low insertion losses and strong coupling strengths in the transmission spectrum. The HIPFG possesses an averaged refractive index (RI) sensitivity of 213.6 nm/RIU nm/RIU in the RI range of 1.33-1.36 and a highest RI sensitivity of 472 nm/RIU at RI of 1.395. In addition, the HIPFG is demonstrated with a low-temperature sensitivity of 3.67 pm/°C, which promises a self-temperature compensation in glucose detection. In the glucose-sensing test, the HIPFG sensor manifests a detection sensitivity of 0.026 nm/(mg/mL) and a limit of detection (LOD) of 1 mg/mL. Moreover, the HIPFG sensor exhibits good stability in 2 h, indicating its capacity for long-time detection. The properties of easy fabrication, high flexibility, insensitivity to temperature, and good stability of the proposed HIPFG endow it with a promising potential for long-term and compact biosensors.

Preparation and Properties of Blended Composite Film Manufactured Using Walnut-Peptide-Chitosan-Sodium Alginate.

In this study, layer-by-layer assembly was performed to prepare sodium alginate (SA) layer and walnut-peptide-chitosan (CS) bilayer composite films. Genipin was adopted to crosslink CS and walnut peptide. The properties of walnut peptide-CS-SA composite film were determined, and the influence of material ratio on the performance of composite film was explored. According to the results, the mechanical tensile property, oil absorption property, and water vapor barrier property of the composite film were improved with the presence of genipin. Moreover, the proportion of CS and walnut peptide had significant effects on color, transmittance, mechanical properties, barrier properties, and antioxidant properties of the composite films. Among them, the composite film containing 1% (w/v) CS, 1% (w/v) walnut peptide, and 0.01% (w/v) genipin showed the best performance, with a tensile strength of 3.65 MPa, elongation at break of 30.82%, water vapor permeability of 0.60 g·mm·m-2·h-1·kPa-1, oil absorption of 0.85%, and the three-phase electrochemistry of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging rate of 25.59%. Under this condition, the tensile property, barrier property, and oxidation resistance of the composite film are good, which can provide a good preservation effect for food, and has great application potential.

Versatile Asymmetric Separator with Dendrite-Free Alloy Anode Enables High-Performance Li-S Batteries.

Lithium-sulfur batteries (LSBs) with extremely-high theoretical energy density (2600 Wh kg-1 ) are deemed to be the most likely energy storage system to be commercialized. However, the polysulfides shuttling and lithium (Li) metal anode failure in LSBs limit its further commercialization. Herein, a versatile asymmetric separator and a Li-rich lithium-magnesium (Li-Mg) alloy anode are applied in LSBs. The asymmetric separator is consisted of lithiated-sulfonated porous organic polymer (SPOP-Li) and Li6.75 La3 Zr1.75 Nb0.25 O12 (LLZNO) layers toward the cathode and anode, respectively. SPOP-Li serves as a polysulfides barrier and Li-ion conductor, while the LLZNO functions as an "ion redistributor". Combining with a stable Li-Mg alloy anode, the symmetric cell achieves 5300 h of Li stripping/plating and the modified LSBs exhibit a long lifespan with an ultralow fading rate of 0.03% per cycle for over 1000 cycles at 5 C. Impressively, even under a high-sulfur-loading (6.1 mg cm-2 ), an area capacity of 4.34 mAh cm-2 after 100 cycles can still be maintained, demonstrating high potential for practical application.

All Fiber-Optic Immunosensors Based on Elliptical Core Helical Intermediate-Period Fiber Grating with Low-Sensitivity to Environmental Disturbances.

An all fiber-optic immunosensor based on elliptical core helical intermediate-period fiber grating (E-HIPFG) is proposed for the specific detection of human immunoglobulin G (human IgG). E-HIPFGs are all-fiber transducers that do not include any additional coating materials or fiber architectures, simplifying the fabrication process and promising the stability of the E-HIPFG biosensor. For human IgG recognition, the surface of an E-HIPFG is functionalized by goat anti-human IgG. The functionalized E-HIPFG is tested by human IgG solutions with a concentration range of 10-100 µg/mL and shows a high sensitivity of 0.018 nm/(µg/mL) and a limit of detection (LOD) of 4.7 µg/mL. Notably, the functionalized E-HIPFG biosensor is found to be insensitive to environmental disturbances, with a temperature sensitivity of 2.6 pm/°C, a strain sensitivity of 1.2 pm/µÎµ, and a torsion sensitivity of -23.566 nm/(rad/mm). The results demonstrate the considerable properties of the immunosensor, with high resistance to environmental perturbations, indicating significant potential for applications in mobile biosensors and compact devices.

Boosting Polysulfide Catalytic Conversion and Facilitating Li+ Transportation by Ion-Selective COFs Composite Nanowire for LiS Batteries.

The large-scale application of lithium-sulfur batteries (LSBs) has been impeded by the shuttle effect of lithium-polysulfides (LiPSs) and sluggish redox kinetics since which lead to irreversible capacity decay and low sulfur utilization. Herein, a hierarchical interlayer constructed by boroxine covalent organic frameworks (COFs) with high Li+ conductivity is fabricated via an in situ polymerization method on carbon nanotubes (CNTs) (C@COF). The as-prepared interlayer delivers a high Li+ ionic conductivity (1.85 mS cm-1 ) and Li+ transference number (0.78), which not only acts as a physical barrier, but also a bidirectional catalyst for LiPSs redox process owing to the abundant heterointerfaces between the inner conductive CNTs and the outer COFs. After coupling such a catalytic interlayer with sulfur cathode, the LSBs exhibit a low decay rate of 0.07% per cycle over 500 cycles at 1 C, and long cycle life at 3 C (over 1000 cycles). More importantly, a remarkable areal capacity of around 4.69 mAh cm-2 can still be maintained after 50 cycles even under a high sulfur loading condition (6.8 mg cm-2 ). This work paves a new way for the design of the interlayer with bidirectional catalytic behavior in LSBs.

Nonporous Gel Electrolytes Enable Long Cycling at High Current Density for Lithium-Metal Anodes.

Lithium-metal anodes with high theoretical capacity and ultralow redox potential are regarded as a "holy grail" of the next-generation energy-storage industry. Nevertheless, Li inevitably reacts with conventional liquid electrolytes, resulting in uneven electrodeposition, unstable solid electrolyte interphase, and Li dendrite formation that all together lead to a decrease in active lithium, poor battery performance, and catastrophic safety hazards. Here, we report a unique nonporous gel polymer electrolyte (NP-GPE) with a uniform and dense structure, exhibiting an excellent combination of mechanical strength, thermal stability, and high ionic conductivity. The nonporous structure contributed to a uniform distribution of lithium ions for dendrite-free lithium deposition, and Li/NP-GPE/Li symmetric cells can maintain an extremely low and stable polarization after cycling at a high current density of 10 mA cm-2. This work provides an insight that the NP-GPE can be considered as a candidate for practical applications for lithium-metal anodes.

Synergy of Sulfur/Polyacrylonitrile Composite and Gel Polymer Electrolyte Promises Heat-Resistant Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries with high theoretical energy density attract great research attention. Although tremendous efforts have been made, heat tolerance capability of Li-S batteries is a topic rarely touched, although it is essential for practical application. At high temperatures, the dissolution of the polysulfides is aggravated, and the safety issue becomes severe. Herein, by using sulfur/polyacrylonitrile (SPAN) composites as positive electrode materials and a gel polymer membrane with carbonate electrolyte, we successfully realized a Li-S battery with remarkable heat-resistant performance at 50°C and 60°C. The SPAN-positive materials allow the Li-S battery operated in safer carbonate-containing electrolyte. The gel polymer electrolyte enhances the charge transfer, maintains the morphology of Li metal during cycling, and suppresses the migration of the soluble polysulfides, which is also observed when SPAN is used as positive electrode material. This contribution would bring new opportunity to extend the application of lithium batteries at high temperatures.

Methods to Improve Lithium Metal Anode for Li-S Batteries.

The lithium-sulfur (Li-S) battery has received a lot of attention because it is characterized by high theoretical energy density (2,600 Wh/kg) and low cost. Though many works on the "shuttle effect" of polysulfide have been investigated, lithium metal anode is a more challenging problem, which leads to a short life, low coulombic efficiency, and safety issues related to dendrites. As a result, the amelioration of lithium metal anode is an important means to improve the performance of lithium sulfur battery. In this paper, improvement methods on lithium metal anode for lithium sulfur batteries, including adding electrolyte additives, using solid, and/or gel polymer electrolyte, modifying separators, applying a protective coating, and providing host materials for lithium deposition, are mainly reviewed. In addition, some challenging problems, and further promising directions are also pointed out for future research and development of lithium metal for Li-S batteries.

Epidemiology, microbiology and therapeutic consequences of chronic osteomyelitis in northern China: A retrospective analysis of 255 Patients.

The study aimed to explore the epidemiology and clinical characteristics of chronic osteomyelitis observed in a northern China hospital. Clinical data of 255 patients with chronic osteomyelitis from January 2007 to January 2014 were collected and analyzed, including general information, disease data, treatment and follow-up data. Chronic osteomyelitis is more common in males and in the age group from 41-50 years of age. Common infection sites are the femur, tibiofibular, and hip joint. More g+ than g- bacterial infections were observed, with S. aureus the most commonly observed pathogenic organism. The positive detection rate from debridement bacterial culture is 75.6%. The detection rate when five samples are sent for bacterial culture is 90.6%, with pathogenic bacteria identified in 82.8% of cases. The two-stage debridement method (87.0%) has higher first curative rate than the one-stage debridement method (71.2%). To improve detection rate using bacterial culture, at least five samples are recommended. Treatment of chronic osteomyelitis with two-stage debridement, plus antibiotic-loaded polymethylmethacrylate (PMMA) beads provided good clinical results in this study and is therefore recommended.

Electroacupuncture alters the expression of genes associated with lipid metabolism and immune reaction in liver of hypercholesterolemia mice.

Acupuncture or electroacupuncture (EA) is effective in treating various metabolism disorders. Previously we found that EA at the acupoint, Fenglong (ST40), had the cholesterol-lowering effect and regulated genes expression in liver of hypercholesterolemia mice (M Li and YZ Zhang, Int J Mol Med 2007, 19: 617-629). To explain gene expression associated with EA, suppression subtractive hybridization (SSH), combined with targeted display (TD), was used and 26 up-regulated and 24 down-regulated genes with known functions were identified in hypercholesterolemia mice liver, some of which are involved in key reactions of lipid metabolism and immune reaction. Promoting lipid metabolism and suppressing inflammation via modulating mRNA expression may be the mechanism of EA inducing modulation of cholesterol concentrations.

Isolation of genes involved in the preventive effect of electroacupuncture at Fenglong acupoint (ST40) on hypercholesterolemia mice by suppression subtractive hybridization (SSH) combined with negative subtraction chain (NSC) technology.

We have shown that electroacupuncture (EA) at Fenglong acupoint (ST40) has the cholesterol-lowering effect in hypercholesterolemia mice. The present study was designed to study preventive effect of EA at ST40 on hypercholesterolemia. C57BL/6j mice were randomly divided into normal group (NG), hypercholesterolemia group (HG) and EA prevention group (EPG). NG were fed chow, HG a hypercholesterolemic diet (HD), and EPG the same HD and received EA treatment simultaneously. Lipid profile of both the plasma and liver indicated that EA at ST40 had preventive effect on hypercholesterolemia. Compared with corresponding values in the HG mice, the levels of the hepatic total cholesterol and total triglyceride in the EPG mice lowered 45% and 23% respectively, and the levels of plasma total-, LDL-, and HDL-cholesterol in the EPG mice lowered 39%, 37% and 39% respectively. Eleven genes whose expressions were up-regulated in EPG mice compared with HG were isolated using suppression subtractive hybridization (SSH) combined with negative subtraction chain (NSC) technology, and then confirmed by dot-blot assay. Except two genes whose functions were still unknown, the others were mainly involved in cholesterol metabolism, lipid metabolism, glucose metabolism and immune response. The potential molecular mechanism of preventive effect was discussed.