[Clinical application of retrosigmoid approach for BONEBRIDGE implantation after auricle reconstruction using expanded postauricular flap]

Objective: To explore the safety and reliability of retrosigmoid approach BONEBRIDGE implantation in patients with auricle reconstruction using skin expansion flap. Methods: A retrospective analysis was conducted on 43 congenital aural atresia cases (43 ears) who underwent BONEBRIDGE implantation from September 2019 to January 2023 in Beijing Tongren Hospital. 30 males and 13 females were included in this work. The implantation age was 9-36 years old (median age=10 y/o). All cases underwent auricle reconstruction surgery using the posterior ear flap expansion method, with 36 cases using the single expanded postauricular flap method and 7 cases using two-flap method. BONEBRIDGE implant surgery was performed during the third stage of auricle reconstruction or after all stages. The hearing improvements were evaluated by comparing the changes in pure tone hearing threshold and speech recognition rate of patients before and after BONEBRIDGE implantation. Routine follow-up was conducted to observe the hearing results and complications. SPSS 14.0 software was applied for data statistical analysis. Results: All 43 patients healed well and had no surgical complications when discharge. The average bone conduction hearing threshold after surgery was (8.2±6.6) dBHL, and there was no statistically significant difference compared to the preoperative [(8.1±5.7) dBHL] (P=0.95). After surgery, the threshold of hearing assistance with power on was significantly lower than that without hearing assistance [(32.8±4.6) dBHL vs (60.5±5.5) dBHL], and the difference was statistically significant (P<0.001). The speech recognition rate of monosyllable words, disyllabic words and short sentences in quiet environment increased to 72%, 84%, and 98% respectively. The differences were statistically significant (P<0.001). The speech recognition rate of monosyllabic words, disyllabic words, and short sentences in noise environment was significantly increased by 70%, 80%, and 92% respectively (P<0.001). After a follow-up of 4 to 47 months (median=24 months), the hearing results were stable and the aesthetic outcomes were satisfying. One patient had delayed hematoma around coil of the implant. After aspiration and compressed dressing for one week, hematoma was not recurrent. Conclusion: For patients after auricle reconstruction using expanded postauricular flap, the preference of retrosigmoid approach is a good choice in terms of safety and reliability of operation, as well as aesthetic appearance.

[Comparison the characteristics of serum adrenocortical hormone profile in patients with adrenal cortical carcinoma and adrenal coritcal adenoma]

Objective: To compare the characteristics of serum adrenocortical hormone profiles detected by liquid chromatography tandem mass spectrometry in patients with adrenal cortical carcinoma and adrenal adenoma. Methods: A total of 23 patients with adrenal cortical carcinoma and 119 patients with adrenal cortical adenoma/hyperplasia who visited the Department of Endocrinology and/or the Department of Urology of Peking University First Hospital from January 2018 to June 2022 were analyzed retrospectively. The imaging characteristics and serum adrenal cortical hormone profiles detected by liquid chromatography tandem mass spectrometry were analyzed retrospectively. The independent related factors of adrenal cortical carcinoma were screened by univariate analysis and multivariate logistic regression analysis. Results: The age of patients with adrenal cortical carcinoma was 46 (35, 57) years, and 15 (65.2%) were female; The age of adrenal cortical adenoma patients was 49 (40, 58) years old, and 80 (67.2%) were female. There was no significant difference in age and gender between the two groups (all P values>0.05). The maximum tumor diameter M (Q₁, Q₃) of patients with adrenocortical carcinoma was 7.05 (5.45, 9.78) cm, which was larger than that of patients with adrenocortical adenoma [2.1 (1.6, 3.0) cm] (P<0.001). Compared with patients with adrenal adenoma, the androstenedione (AD) of patients with adrenal cortical carcinoma [4.056 9 (1.619 5, 7.907 9) nmol/L vs 1.517 5 (0.935 1, 2.582 1) nmol/L (P<0.001)] was significantly increased; 11-ketotestosterone/11-ketoandrostenedione [0.034 3 (0.020 6, 0.079 2) vs 0.041 0 (0.028 6, 0.061 5) (P=0.089)] and 11-ketoandrostenedione/11-hydroxyandrostenedione [0.013 0 (0.006 4, 0.086 7) vs 0.063 0 (0.018 2, 0.162 5) (P=0.042)] were significantly decreased. Multivariate analysis found that AD, the largest diameter of the tumor, 11-ketotestosterone/11-ketoandrostenedione and 11-ketoandrostenedione/11-hydroxyandrostenedi-one were related factors for adrenal cortical carcinoma, with OR values (95%CI) of 1.841 (1.093-3.100), 5.130 (2.332-11.285), 0.381 (0.167-0.867) and 0.000 (0.000-0.014), respectively, all P values <0.05. Conclusions: The larger diameter of adrenal cortical tumor and the higher the level of androstenedione are independent risk factors for adrenal cortical carcinoma. The reduction conversion of 11-hydroxyandrostenedione to 11-ketoandrostenedione and 11-ketoandrostenedione to 11-ketotestosterone were independently associated with adrenal cortical carcinoma.

Whispering gallery mode microsphere resonator based on cylindrical air cavity coupling

In this Letter, an optical fiber whispering gallery mode microsphere resonator based on cylindrical air cavity coupling is proposed and demonstrated. The cylindrical air cavity is vertical to the axis of a single-mode fiber and in touch with the fiber core, fabricated by using femtosecond laser micromachining together with hydrofluoric acid etching. A microsphere is inserted into the cylindrical air cavity and in tangential contact with the inner cavity wall, which is in touch with or inside the fiber core. The light traveling in the fiber core is coupled into the microsphere via an evanescent wave when the light path is tangential to the contacting point of the microsphere and the inner cavity wall, resulting in whispering gallery mode resonance when the phase-matching condition is satisfied. Such a device is highly integrated, robust in structure, low in cost, stable in operation, and has a good quality factor (Q) of 1.44 × 10⁴.

All-fiber saturable absorber based on slightly tapered graded index multimode fiber for conventional and bound soliton generation

A slightly tapered graded index multimode fiber (GIMF) is demonstrated as the saturable absorber (SA) for a conventional soliton and tightly bound soliton generation. The SA device is simply a GIMF spliced with single-mode fiber (SMF) at its two ends. The waist diameter of the slightly tapered fiber is ∼23.8µm, located at one of the splicing points of SMF and GIMF. The mode-locked output of conventional solitons and tightly bound solitons can be obtained in a ring fiber laser based on such a SA. The central wavelength of the output conventional solitons is 1563.5 nm, and the pulse width is as short as 473 fs at the fundamental frequency of 19.53 MHz. The central wavelength of the tightly bound solitons is 1563.5 nm, with a pulse width of 636 fs and a separation of 1.89 ps. The device is featured with a simple and robust structure and stable operation capability and can effectively overcome the difficulty in requirement of precise control of the GIMF length, which make it attractive in ultrafast lasers and optical fiber communication systems.

Ultra-short long-period fiber grating based on a micro air-channel structure

A new type of long-period fiber grating is proposed and demonstrated. The structure of the device consists of a few micro air-channels along a single-mode fiber, and is fabricated by using a femtosecond laser to inscribe a few groups of fiber inner waveguide arrays followed by hydrofluoric acid etching. The length of the long-period fiber grating is down to 600 µm, corresponding to only five grating periods. To the best of our knowledge, this is the shortest long-period fiber grating reported. The device has a good refractive index sensitivity of ∼587.08 nm/RIU (refractive index unit) in the refractive index range of 1.34-1.365 and a relatively small temperature sensitivity of ∼12.1 pm/°C, thus reducing the temperature cross-sensitivity. Such a device is expected to have promising photonic applications.

Multimode fiber surface plasmon resonance sensor based on a down-up taper

A multimode fiber surface plasmon resonance sensor based on a down-up taper for refractive index measurement is proposed and demonstrated. The device is fabricated by splicing two multimode fibers in a heating and pushing process to form an up taper, followed by heating and pulling the fiber adjacent to the up-taper area to form a down taper, and then using a magnetron sputtering technique to deposit a Cr + Ag layer of 50 nm on the surface of the down-up taper. Such a structure effectively increases the taper ratio and hence improves the measurement sensitivity. The experimental results obtained show that in the refractive index range of 1.345-1.375, the refractive index sensitivity achieved is ∼3264.01 nm/RIU. The device has a compact size and its entire length is ∼2.75 mm. Moreover, the robustness of the device is better than that of the previously reported fiber surface plasmon resonance sensors due to its relatively large waist diameter of 40 µm for the down taper. The device is expected to have potential applications in biological and chemical sensing.

Structural basis of ion - substrate coupling in the Na+-dependent dicarboxylate transporter VcINDY

The Na+-dependent dicarboxylate transporter from Vibrio cholerae (VcINDY) is a prototype for the divalent anion sodium symporter (DASS) family. While the utilization of an electrochemical Na+ gradient to power substrate transport is well established for VcINDY, the structural basis of this coupling between sodium and substrate binding is not currently understood. Here, using a combination of cryo-EM structure determination, succinate binding and site-directed cysteine alkylation assays, we demonstrate that the VcINDY protein couples sodium- and substrate-binding via a previously unseen cooperative mechanism by conformational selection. In the absence of sodium, substrate binding is abolished, with the succinate binding regions exhibiting increased flexibility, including HPinb, TM10b and the substrate clamshell motifs. Upon sodium binding, these regions become structurally ordered and create a proper binding site for the substrate. Taken together, these results provide strong evidence that VcINDY's conformational selection mechanism is a result of the sodium-dependent formation of the substrate binding site.

The ups and downs of elevator-type di-/tricarboxylate membrane transporters

The divalent anion sodium symporter (DASS) family contains both sodium-driven anion cotransporters and anion/anion exchangers. The family belongs to a broader ion transporter superfamily (ITS), which comprises 24 families of transporters, including those of AbgT antibiotic efflux transporters. The human proteins in the DASS family play major physiological roles and are drug targets. We recently determined multiple structures of the human sodium-dependent citrate transporter (NaCT) and the succinate/dicarboxylate transporter from Lactobacillus acidophilus (LaINDY). Structures of both proteins show high degrees of structural similarity to the previously determined VcINDY fold. Conservation between these DASS protein structures and those from the AbgT family indicates that the VcINDY fold represents the overall protein structure for the entire ITS. The new structures of NaCT and LaINDY are captured in the inward- or outward-facing conformations, respectively. The domain arrangements in these structures agree with a rigid body elevator-type transport mechanism for substrate translocation across the membrane. Two separate NaCT structures in complex with a substrate or an inhibitor allowed us to explain the inhibition mechanism and propose a detailed classification scheme for grouping disease-causing mutations in the human protein. Structural understanding of multiple kinetic states of DASS proteins is a first step toward the detailed characterization of their entire transport cycle.

Long-period fiber grating based on inner microholes in optical fiber

A new, to the best of our knowledge, type of long-period fiber grating based on inner microholes in an optical fiber core is proposed and demonstrated. The device is fabricated by first using a femtosecond laser to write a series of vertical short line structures in the core of a single-mode fiber, followed by discharge of the short line areas with a fusion splicer. Owing to the high temperature generated, the line structure rapidly expands and forms an inner microhole. The device is found to have good high temperature sustainability up to 1000°C, with a sensitivity of approximately 13 pm/°C and its strain and bending sensitivities are approximately -1.57 pm/µɛ and -5.198 dB/m^-1, in the ranges of 0-800 µɛ and 0-0.77 m^-1, respectively. It is expected that the device can contribute to the multi-parameter sensing and detection of high temperature in harsh environments.

Microfiber sensor probe integrated with a cascaded Fabry-Perot interferometer

Developing micrometer-nanometer size optical fiber sensors has promising application prospects in microenvironments, such as biological cells, micro robots, and microfluids. We propose a new strategy to fabricate a microfiber sensor probe (MSP). A femtosecond laser was applied to integrate cascaded Fabry-Perot interferometers (FPIs) into a silica microfiber. And a MSP with diameter of ∼8µm, extinction ratio of 15 dB, fitness of 24.6, and Q-factor of 2310 was demonstrated in the experiment. In addition, the MSP was applied for the refractive index and thermal measurement and the sensitivity was observed to be 10 pm/°C and 18.5 nm/RIU. The two-beam approximation model was applied to analyze the spectrum, and simulations were taken to research the refractive index sensitivity influenced by the fiber size.

[Evaluation of adhesive bone conduction hearing aid in pediatric patients with unilateral congenital aural atresia]

Objective: To evaluate the auditory efficacy and subjective satisfaction of adhesive bone conduction hearing aid in children with unilateral congenital aural atresia (UCAA). Methods: Ten subjects (5 males and 5 females) diagnosed with UCAA with an average age of 8.3 years old (ranged from 5 to 15) were included in Beijing Tongren Hospital, Capital Medical University from January to August 2019. The free sound field hearing threshold, word recognition score in quiet, speech reception threshold in noise and sound localization ability (results were measured by RMS error) tests were performed in unaided and aided situation, respectively. Subjective satisfaction questionnaires were also distributed to subjects. Paired t test and Wilcoxon signed rank test were used as statistical analysis methods. Results: The average hearing threshold in aided condition was improved by (21.9±4.4) dB (t=15.8，P<0.05). Speech recognition abilities were generally improved both under quiet and noise (P<0.05);however, when the binaural summation, squelch and head shadow effects were analyzed respectively, the binaural squelch effect was not statistically improved (P>0.05), while the other effects were improved in aided condition (P<0.05). In sound localization test, there was no significant difference of the RMS error value between the unaided and aided situation (P>0.05). The subjects got high satisfaction rates in three subjective questionnaires. Conclusion: The adhesive bone conduction hearing aid can provide significant audiological benefit for children with UCAA as well as raising the quality of their life.

Coupling scheme for graphene saturable absorber in a linear cavity mode-locked fiber laser

A saturable absorber based on a graphene layer covered single-mode fiber with inner short waveguides is proposed and demonstrated for a linear cavity Er-doped mode-locked fiber laser. A pair of short waveguides is written in the fiber by using femtosecond micromachining technology, and the propagating light is guided by one short waveguide to the cladding-air interface and interacts with the graphene layer in the form of evanescent waves before being collected back to the core by another short waveguide, and, as a result, the saturable absorption is excited. The designed saturable absorber is used in the passively mode-locked fiber laser to generate traditional soliton mode-locked pulse output with the center wavelength of 1564.9 nm and pulse width of 758 fs at the fundamental frequency of 22.58 MHz. The fabricated saturable absorber device is stable in operation, compact in structure, safe for thermal damage, and can effectively overcome the shortcomings of poor robustness of the saturable absorbers based on a tapered fiber and D-shaped fiber. This provides a new optical coupling scheme for saturable absorbers based on 2D materials such as graphene and has great potential application in the field of ultrashort pulse lasers.

[Effect of γ-secretase inhibitor on middle ear ultrastructures in ovalbumin-mediated otitis media with effusion in rats]

Objective: To study the effect of the inhibitor of Notch signaling pathway-γ-secretase inhibitor DAPT on the ultrastructures of middle ear in the ovalbumin (OVA)-mediated allergic OME in vivo. Methods: Male Sprague-Dawley (SD) rats, weighing 250-300 g, were completely and randomly divided into three groups (5 rats, 10 ears in each group):(1)Control group(2)OME group(3)OME+DAPT group. Rats in the OME group underwent systemic and local sensitization by intraperitoneal and intratympanic injection of ovalbumin to make the model of OVA-induced OME. Rats in the control group were sensitized with PBS. On the basis of establishing the OME model, OME+DAPT group were intraperitoneal injected with DAPT (10 mg/kg) for seven consecutive days and were administered before intratympanic injection of ovalbumin. After the model was successfully established, endoscopy,H&E staining and scanning electron microscopy were used to study the histology and mucous-ciliary ultrastructures of the non-ciliated and ciliated mucosa in the middle ear of each group. One-way ANOVA and Tukey methods were used for statistical analysis. Results: H&E staining showed that the three groups had statistically significant differences in submucosal thickness both in non-ciliated and ciliated regions (non-ciliated area:(6.83±1.47)μm, (38.58±9.57)μm, (32.17±11.89)μm, respectively. F=107.9;cilia area:(26.69±3.22)μm, (30.41±6.75)μm, (26.76±4.06)μm, respectively. F=5.62,both P<0.01). The thickness of the submucosa in the non-ciliated area and the cilia area of the OME group were significantly thicker than that of control group (F=42.08 and 4.40,both P<0.05); the thickness of the non-ciliated area and the ciliated area in OME+DAPT group were reduced compared to OME group(F=1.55 and 2.77,both P<0.05). Scanning electron microscopy showed that the array of cilia on the middle ear mucosa was disorderly arranged and inversed, this phenomenon was relieved in the OME+DAPT group. The number of goblet cells in the control group, OME group, and OME+DAPT group were 9.87±1.92; 15.67±5.77; 10.33±1.99 respectively and the difference between them was statistically significant (F=11.43, P<0.01). The number of goblet cells in the OME group were significantly higher than those in the control group (F=9.00,P<0.01) and the number of goblet cells in the OME+DAPT group were decreased compared to those of OME group (F=8.41, P<0.01). Conclusions: The study demonstrates the pathological changes of the ultrastructure in middle ear in OVA-induced OME and the effect of the γ-secretase inhibitor on it. In OME group, the cilia are disorderly arranged and inversed, the number of goblet cell is increased and they are swelled which suggest the hypersecretion of the mucus. DAPT can regulate OVA-induced allergic inflammation and relieve pathological changes of ultrastructure in middle ear mucociliary transport system through alleviating submucosal inflammation, reducing the hypersecretion of goblet cell and the morphological damage of cilia through the Notch signaling pathway.

Ultra-high sensitivity strain sensor based on biconical fiber with a bulge air-bubble

An ultra-high sensitivity Fabry-Perot interferometer (FPI) strain sensor is proposed and experimentally demonstrated. It is composed of a biconical fiber with a bulge air-bubble at its waist. Because of the good stress concentration capability of the tapered fiber, the bulge air-bubble is easily deformed when it is stressed, resulting in an ultra-high strain sensitivity of 101.7 pm/µɛ, which is the highest strain sensitivity among the direct wavelength interrogation-based strain sensors reported so far, to the best of our knowledge. Moreover, the proposed sensor has a low temperature sensitivity of ∼1pm/^∘C; thus an extreme low temperature cross sensitivity of less than 10 nɛ/°C can be achieved.

[Bonebridge implantation combined with simultaneous bilateral auricle reconstruction for bilateral congenital aural atresia]

Objective: To investigate the feasibility and safety of auricle reconstruction combined with Bonebridge implantation for bilateral aural atresia patients. Methods: A retrospective analysis was conducted for 36 cases(72 ears) who underwent Bonebridge implantation combined with bilateral auricle reconstruction from February 1, 2017 to January 15, 2020. All cases were bilateral congenital aural atresia and underwent Nagata auricle reconstruction for both sides simultaneously. Bonebridge implantations were performed during the second stage of auricle reconstruction. Results: All 36 patients healed well and had no surgical complications when discharged. The preoperative average bone conduction threshold of the patients was(8.5±5.8) dB HL and postoperative bone conduction threshold was (8.4±5.2) dB HL. There was no significant change after the implantation (P=0.724). The preoperative average air conduction threshold of was(64.9±7.4)dB HL and postoperative air conduction threshold was (24.0±5.3) dB HL, which had a significant change after the implantation (P<0.001). The hearing threshold with Bonebridge significantly decreased by 40.9 dB HL compared with the preoperative air conduction threshold(P<0.001). The speech recognition rate of monosyllable words, disyllabic words and short sentences in quiet environment increased by 62.5%, 63.5% and 72.2% respectively. The differences were statistically significant (P<0.001). The speech recognition rate of monosyllabic words, disyllabic words and short sentences in noise environment were significantly increased by 55.9%, 58.9% and 69.9% respectively (P<0.001). After a follow-up of 18.3 months in average, the hearing results were stable and the aesthetic outcomes were satisfied. One patient had implant rupture and healed after revision surgery. Conclusions: With an integrated surgical procedure, patients with bilateral congenital aural atresia can complete bilateral auricle reconstruction and hearing implantation within six months. This integrated surgical procedure is safe and efficient, with a stable hearing improvement and good appearance.

Simultaneous refractive index and temperature sensing based on a fiber surface waveguide and fiber Bragg gratings

An optical fiber sensor based on a fiber surface waveguide and Bragg grating is proposed for a simultaneous refractive index (RI) and temperature sensing. The device consists of two fiber Bragg gratings fabricated by a femtosecond laser, one of which is situated in the fiber core for temperature sensing; the other is located in the fiber surface waveguide for both temperature and RI measurements. The RI and temperature sensitivities achieved are 10.3 nm/RIU and 9.94 pm/°C, respectively. The device is featured with a compact structure, high robustness, and convenient operation.

Structure and inhibition mechanism of the human citrate transporter NaCT

Citrate is most well-known as an intermediate in the TCA cycle of the cell. In addition to this essential role in energy metabolism, the tricarboxylate anion also acts as both a precursor and a regulator of fatty acid synthesis ^1–3. Thus, the rate of fatty acid synthesis correlates directly with the cytosolic citrate concentration ^4,5. Liver cells import citrate via the sodium-dependent citrate transporter NaCT (SLC13A5), and as a consequence this protein is a potential target for anti-obesity drugs. To understand the structural basis of its inhibition mechanism, we have determined cryo-electron microscopy structures of human NaCT in complex with citrate and with a small molecule inhibitor. These structures reveal how the inhibitor, bound at the same site as citrate, arrests the protein’s transport cycle. The NaCT-inhibitor structure also explains why the compound selectively inhibits NaCT over two homologous human dicarboxylate transporters, and suggests ways to further improve the affinity and selectivity. Finally, the NaCT structures provide a framework for understanding how various mutations abolish NaCT’s transport activity in the brain and thereby cause SLC13A5-Epilepsy in newborns ^6–8.

High-power synchronous multi-wavelength solitons from a multimode mode-locked fiber laser system

In this Letter, we implement a multimode fiber (MMF) laser system mode-locked by a nonlinear polarization rotation technique for controllable synchronous multi-wavelength soliton generation. The synchronization of the repetition rates for different wavelengths is realized by the special mode transmission in MMF. For dual-wavelength mode-locking at 1566.7 nm and 1617.2 nm, each of the synchronously mode-locked solitons consists of a train of quasi-periodic beat pulses with a pulse width of 84 fs and period of 162 fs. The total output power reaches 532 mW with optimally balanced two-color intensities. Furthermore, switchable dual- and tri-wavelength synchronized femtosecond pulses are also obtained. In contrast to previous reports, this synchronously mode-locked multi-wavelength is output directly from a laser oscillator, which provides a simpler candidate to achieve pulse synchronization.

Optical fiber surface waveguide with Fabry-Perot cavity for sensing

A parallel structured optical fiber Fabry-Perot interferometer sensor is proposed and demonstrated for refractive index and strain sensing with low temperature cross sensitivity. The device consists of two Fabry-Perot cavities fabricated by a femtosecond laser: one is inscribed in the fiber surface waveguide and used for sensing, and the other one is located in the fiber core for referencing. Part of the light propagating in the fiber core can be directed to the fiber surface waveguide via an X coupler. Because of the evanescent field, the light traveling along the fiber surface waveguide interacts with the surrounding medium and enables external refractive index sensing. The measurement sensitivity of the device is enhanced due to the Vernier effect associated with the parallel structured two Fabry-Perot interferometers. The sensitivities of ∼843.3nm/RIU and ∼101.8pm/µε have been obtained for refractive index and strain, respectively, and the corresponding temperature cross sensitivities are ∼9.6×10^-6RIU/^∘C and ∼7.956×10^-2µε/^∘C, respectively. The device is featured with high robustness, compact size, and large sensitivity.

Structural basis for the reaction cycle of DASS dicarboxylate transporters

Citrate, α-ketoglutarate and succinate are TCA cycle intermediates that also play essential roles in metabolic signaling and cellular regulation. These di- and tricarboxylates are imported into the cell by the divalent anion sodium symporter (DASS) family of plasma membrane transporters, which contains both cotransporters and exchangers. While DASS proteins transport substrates via an elevator mechanism, to date structures are only available for a single DASS cotransporter protein in a substrate-bound, inward-facing state. We report multiple cryo-EM and X-ray structures in four different states, including three hitherto unseen states, along with molecular dynamics simulations, of both a cotransporter and an exchanger. Comparison of these outward- and inward-facing structures reveal how the transport domain translates and rotates within the framework of the scaffold domain through the transport cycle. Additionally, we propose that DASS transporters ensure substrate coupling by a charge-compensation mechanism, and by structural changes upon substrate release.

Predicting the optimal growth temperatures of prokaryotes using only genome derived features

MOTIVATION

Optimal growth temperature is a fundamental characteristic of all living organisms. Knowledge of this temperature is central to the study of a prokaryote, the thermal stability and temperature dependent activity of its genes, and the bioprospecting of its genome for thermally adapted proteins. While high throughput sequencing methods have dramatically increased the availability of genomic information, the growth temperatures of the source organisms are often unknown. This limits the study and technological application of these species and their genomes. Here, we present a novel method for the prediction of growth temperatures of prokaryotes using only genomic sequences.

RESULTS

By applying the reverse ecology principle that an organism's genome includes identifiable adaptations to its native environment, we can predict a species' optimal growth temperature with an accuracy of 5.17°C root-mean-square error and a coefficient of determination of 0.835. The accuracy can be further improved for specific taxonomic clades or by excluding psychrophiles. This method provides a valuable tool for the rapid calculation of organism growth temperature when only the genome sequence is known.

AVAILABILITY AND IMPLEMENTATION

Source code, genomes analyzed and features calculated are available at: https://github.com/DavidBSauer/OGT_prediction.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Integrated in-fiber coupler for a whispering-gallery mode microsphere resonator

An integrated in-fiber coupler is proposed and demonstrated, which can excite whispering-gallery mode (WGM) in a microsphere resonator. This device is fabricated firstly by using femtosecond laser micromachining and a fusing splicing technique to create an inner air cavity with a suspended fiber core, then an open micro-channel is drilled on the top of the inner air cavity, and finally a microsphere is placed inside the air cavity, in contact with the suspended fiber core, to excite the WGM through the evanescent field. In the transmission spectrum of the device, the slopes of the two asymmetric Fano resonance lines of 41.12 dB/nm and $ - {18.46}\;{\rm dB/nm}$-18.46dB/nm, respectively, and a symmetrical Lorentz line with a quality factor of ${9.32} \times {{10}^3}$9.32×10³ can be obtained simultaneously. Such an in-fiber WGM microsphere resonator has the advantages of compact structure, convenient operation, and high durability.

Parallel structured optical fiber in-line Fabry-Perot interferometers for high temperature sensing

We propose and demonstrate parallel structured optical fiber in-line Fabry-Perot interferometers for high temperature sensing. The device consists of three Fabry-Perot cavities in parallel connection, which allows three independent fringe patterns superimposed at its output, and, as a result, a number of dominant fringe peaks/dips appear, thus enabling unambiguous measurement in a large range. The device is featured with compact size, robust structure, and excellent high temperature sustainability, which makes it promising in extreme environment monitoring.

Multiresidue Gas Chromatographic Method for Determining Synthetic Pyrethroid Pesticides in Agricultural Products: Collaborative Study

Fourteen laboratories from 6 countries and regions participated in an international collaborative study to evaluate a multiresidue gas chromatographic (GC) method for determining 8 synthetic pyrethroid pesticides in grains, fruits, and vegetables. The study design was based on Youden’s matched-pairs principle for collaborative tests of analytical methods. Each laboratory analyzed 12 collaborative samples of wheat, oranges, and tomatoes as blind samples. Wheat samples were extracted with acetonitrile–water (2 + 1), while orange and tomato samples were extracted with acetone. Residues were partitioned into hexane, evaporated to dryness with a rotary evaporator, and then dissolved in hexane. The hexane extract was partitioned with acetonitrile and cleaned up on a 5% water-deactivated Florisil column with 6% ethyl ether in hexane as eluant. Residue concentrations were determined by GC with electron capture detection with split-less injection by comparison with single-point calibration standards. The appropriate standard concentration was determined by screening sample extracts before analysis. The multiresidue method was tested over the concentration range of 0.0951.909 mg/kg depending on the 8 different of pesticides and agricultural products analyzed in the collaborative study. Statistical analysis of data from 13 laboratories showed weighted average recoveries for 8 pyrethroids in wheat, oranges, and tomatoes at 0.105–1.909,0.095–1.909, and 0.105–0.954 mg/kg, respectively, ranging from 91.8 to 100.2%, from 88.1 to 100.6%, and from 88.2 to 101.5%, respectively. Reproducibility relative standard deviation values ranged from 6.46 to 17.74%, from 5.94 to 18.13%, and from 5.59 to 10.48%, respectively. Repeatability relative standard deviation values ranged from 6.34 to 10.84%, from 5.19 to 11.72%, and from 3.20 to 8.09%, respectively. The multiresidue GC method for determining synthetic pyrethroid pesticides in agricultural products has been adopted first action by AOAC INTERNATIONAL.

Cascaded multiple Fabry-Perot interferometers fabricated in no-core fiber with a waveguide for high-temperature sensing

An optical fiber high-temperature sensor is proposed and demonstrated by use of cascaded multiple Fabry-Perot interferometers in no-core fiber with a waveguide fabricated by femtosecond laser pulse inscription. The device can sustain the high temperature up to 1100°C, and the temperature sensitivity obtained is 8.9 pm/°C within the temperature range 100°C-400°C, and 16.36 pm/°C within the temperature range 400°C-1100°C, respectively. Such a no-core fiber-based device can be fabricated in a simple way and operated reliably, which makes it attractive for extreme environment monitoring.

Highly sensitive PDMS-filled Fabry-Perot interferometer temperature sensor based on the Vernier effect

A highly sensitive temperature sensor is demonstrated experimentally, which is fabricated based on a Fabry-Perot interferometer (FPI) filled with polydimethylsiloxane (PDMS). The sensor's sensitivity is -0.653  nm/°C by utilizing the thermal expansion effect of PDMS, which has been greatly improved compared to that of the traditional FPI temperature sensor. Moreover, in order to further improve the sensitivity, a scheme where two parallel FPI structures are used to form the Vernier effect is proposed, which are a sensing FPI and reference FPI, respectively. Such a temperature sensor based on the FPI filled with PDMS and the Vernier effect exhibits a high temperature sensitivity of 17.758 nm/°C. Meanwhile, the proposed sensors show the advantages of high sensitivity, simplicity, and low cost.

[Congenital microtia with aural atresia or stenosis accompany with first branchial cleft anomaly: report of 5 cases]

Objective: To summarize the experience of the diagnosis, treatment and effects of the cases with coexistence of first branchial cleft anomaly(FBCA) and microtia with congenital aural atresia or stenosis(external auditory canal stenosis, EACS). Method: This was a retrospective study. The clinical data of 5 patients with microtia and EACS in Beijing Tongren Hospital of Capital Medical University from October 2015 to March 2018 were collected, including 3 males and 2 females, aged from 5 to 28 years. The clinical characteristics, imaging findings, treatment methods and effects of 5 patients were analyzed. Result: The 5 cases were all coexistence of EACS and FBCA, three of who associated with cholesteatoma of external auditory canal. CT showed external auditory canal stenosis with soft tissue shadow, sometimes gas or bone septum found inside, filling in the external auditory canal, combined with canal bone destruction irregularly. All patients underwent surgical resection of FBCA, 3 patients accompanied by cholesteatoma resection and canalplasty. The postoperative follow-up ranged from 10 to 39 months, and no recurrence of infection was observed. Conclusions: EACS and FBCA both result from maldevelopment of the first branchial cleft. These two malformations, FBCA and EACS with or without cholesteatoma, can occur simultaneously, in which situation CT shows external auditory canal stenosis with soft tissue shadow inside. These patients underwent surgical resection of FBCA combined with cholesteatoma resection with good result.

[Establishment and evaluation of a triple-color human papillomavirus pseudovirion neutralization assay]

Objective: To establish a triple-color pseudovirion-based neutralization assay (PBNA) and evaluate its capability of detecting immunogenicity of the sera generated by the immunization of HPV 9-valent vaccine. Methods: HPV pseudovirus (PsVs) 6/11/16/18/31/33/45/52/58 with the encapsidated fluorescence expressing red fluorescent plasmid N31-MCHREEY, green fluorescent N31-EGFP or blue fluorescent N31-mTagBFP were generated. The concentration of HPV PsVs and the infection titers of HPV PsVs were detected by double-antibody sandwich ELISA and TCID(50), respectively. The single- and triple color HPV 16/33/45 PsVs were used to detect the neutralization titers of mice sera immunized with HPV 9-valent vaccine and confirmed the accuracy and specificity of the triple-color PBNAs. Then, the single- and triple color HPV 6/11/18/31/33/45/52/58 PsVs were employed to detect the neutralization titers of cynomolgus macaques sera immunized with HPV 9-valent vaccine and determined whether the triple-color PBNAs could be applied to evaluate the immunogenicity of the sera generated by the immunization of HPV9-valent vaccine. Results: The concentration of HPV16 PsVs encapsulating green, red or blue fluorescent plasmid was 5.0 to 6.0 μg/ml and HPV6/11/18/31/33/45/52/59 triple-color HPV PsVs was about 1.0 to 3.0 μg/ml. 9 types HPV PsVs containing EGFP, Mcherry or mTagBFP reporter plasmid were obtained and the concentration can meet the need of neutralization detection. 9 types single-color fluorescent HPV PsVs had similar infectivity against 293FT cells with the infection titer values between 1×10(4) and 1×10(5). The results of PBNAs showed that there was no significant difference in the anti-HPV neutralization titers of mice sera induced by HPV 9-valent vaccine between single-color and triple-color HPV16/33/45 PsVs (P>0.05). Similarly, there was also no significant difference in the anti-HPV neutralization titers of cynomolgus macaques sera induced by HPV 9-valent vaccine between single-color and triple-color HPV6/11/18/31/33/45/52/58 PsVs (P>0.05). Conclusion: We successfully established the triple-color PBNAs and verified the accuracy and specificity of triple-color PBNAs consistent with single-color PBNAs. The triple-color PBNAs can be applied to evaluate the immunogenicity of HPV 9-valent vaccine's immune serum.

Construction of cascaded Fabry-Perot interferometers by four in-fiber mirrors for high-temperature sensing

An optical fiber high-temperature sensor is proposed and demonstrated by use of cascaded Fabry-Perot interferometers based on four in-fiber mirrors fabricated by femtosecond laser inscription. The output fringe pattern of the device exhibits dominant/highly distinguishable dip wavelength, which helps in unambiguous measurement beyond the free spectral range. The device has excellent thermal stability in high temperature up to 1100°C, and the temperature sensitivity obtained is 9.91 pm/°C within the temperature range of 100°C to 400°C, and 15.88 pm/°C within the temperature range of 400°C to 1100°C, respectively. The device features compact size, simple fabrication, and convenient operation, which make it attractive for monitoring of extreme environment.

In-line reflective Mach-Zehnder interferometer based on a tilted in-fiber beam splitter

A fiber in-line reflective Mach-Zehnder interferometer is proposed and experimentally demonstrated, which is based on a tilted in-fiber beam splitter inscribed by a femtosecond laser. The beam splitter splits the incident light beam into two parts; one is directed to the fiber cladding-air interface, where it experiences total internal reflection and is directed to the fiber core. The other part of the light beam keeps traveling in the fiber core. The two parts of the light beams are recombined in the fiber core to generate interference before being reflected at the fiber cut end face. The device proposed is compact in size, robust in mechanical strength, easy in fabrication, and can be used for environmental refractive index sensing in a convenient manner.

Generation of pulse-width controllable dissipative solitons and bound solitons by using an all fiber saturable absorber

A passively mode-locked fiber laser with controllable pulse width is demonstrated by use of an all-fiber saturable absorber based on a hybrid no-core fiber (NCF)-graded index multimode fiber (GIMF) structure incorporated into an Er-doped fiber ring cavity. Such a hybrid NCF-GIMF structure has a tunable intracavity filtering effect. As a result, the mode-locking operation is achieved with controllable pulse width and spectral bandwidth in the normal dispersion regime by only stretching the fiber device. Soliton pulses with the pulse width of 7.7-23 ps are generated, and bound solitons with variable widths are also experimentally demonstrated. The results obtained reveal the versatility and flexibility of the NCF-GIMF structured device in controlling the pulse dynamics for different experimental requirements.

Hollow-Core-Photonic-Crystal-Fiber-Based Miniaturized Sensor for the Detection of Aggregation-Induced-Emission Molecules

A miniature sensor for detection of aggregation-induced-emission (AIE) molecules is proposed in this work. The sensing head is fabricated by use of hollow-core photonic crystal fiber with a core diameter of about 4.8 μm. The cladding holes are sealed with a fusion splicing technique, and the central hole remains open to allow the filtration of solution with AIE molecules. When the solution is excited by an ultraviolet lamp, the fluorescence is received by a fiber-optic spectrometer. The fluorescence intensity is associated with the concentration of AIE molecules and the infiltrated-core length. In the whole process of the experiments, the output-peak wavelength is stable, which indicates that the existing forms of AIE particles are stable, and the fluorescence reabsorption can be neglected. The experimental results obtained are in accordance with traditional microplate-spectrophotometer methods. The most exciting result is that the amount of sample measured can be as low as 0.36 nL, which allows the detection of AIE molecules at only 0.02 pmol. In addition, the miniature sensor was successfully applied to the detection of an AIE-based bioprobe for evaluating the activity of the dipeptidyl-peptidase 4 (DPP-4) inhibitor sitagliptin with an IC₅₀ of 59.80 ± 3.06 nM. The advantages of small device size and nanoliter-scale sample volumes suggest that the proposed sensor is promising for many biosensing applications.

Whispering-gallery-mode excitation in a microsphere by use of an etched cavity on a multimode fiber end

In this Letter, we demonstrate a whispering-gallery-mode (WGM) microsphere resonator. The device is fabricated by fusion splicing a section of no-core fiber with multimode fiber (MMF) and single-mode fiber at its two ends. The open end of the MMF is etched to create an arc-shaped cavity, with a microsphere glued at its bottom. When the arc of the cavity bottom and microsphere surface are tangent, part of the incident light is coupled into the microsphere and travels exactly one circle before being directed back to the MMF core along the tangent line and exciting the WGM. The device has a Q-factor of 1.21×10⁴, and is robust in structure and low in cost.

In-fiber beam splitters for construction of in-line Michelson interferometers

We demonstrate optical fiber in-line Michelson interferometers based on two in-fiber beam splitters crossing the core of a single-mode fiber, fabricated by a femtosecond laser. The in-fiber beam splitter reflects part of the incident light to the air-cladding interface before being reflected back while passing the rest to travel along the fiber core. The two in-fiber beam splitters, air-cladding interfaces, and the cutting fiber end face together form a combined three in-line Michelson interferometers. This Michelson interferometer device is robust in mechanical strength, easy in fabrication, compact in size, and low in cost.

Femtosecond laser inscribed straight waveguide in no-core fiber for in-line Mach-Zehnder interferometer construction

A new fiber in-line Mach-Zehnder interferometer based on a straight waveguide along the central axis of the no-core fiber sandwiched between single mode fibers is fabricated by a femtosecond laser. The device can be used for high temperature sensing with a sensitivity of -278.86  pm/°C and for bending sensing with a sensitivity of 0.28  nm/m^-1. The high mechanical strength, simple fabrication, and precisely controlled free spectral range make the device attractive for potential applications in high temperature monitoring.

[The relationship between core members' individual social capital and performance among HIV/AIDS related community-based organization]

Objective: To investigate the relationship between core members' social capital and performance among HIV/AIDS-related community-based organizations (CBO). Methods: From July to December in 2015, a total of 327 core members from 212 HIV/AIDS-related CBO in 8 provinces were recruited based on the prevalence of HIV/AIDS (e.g., Yunnan, Hunan, and Sichuan are in high epidemic level; Anhui, Hubei, Shandong, and Jilin are in middle epidemic level; and Gansu is in low epidemic level) by multistage stratified cluster sampling and convenient sampling method. A questionnaire was administered in this study, including general demographic information, core members' social capital, individual performance and organizational performance. Multivariate logistic regression model was used to analyze the relationship between core members' social capital and performance among CBO. Results: Among the 327 individuals, the proportion of male was 201(61.47%). The proportion of core members from grassroots CBO was 66.97% (219/327). Core members from non-grassroots organizations were more likely to publish articles, the OR (95%CI) was 2.58 (1.30-5.14); Social network had a positive impact on the AIDS experts, the OR (95%CI) was 2.41(1.47-3.95); Core members from registered CBO were more likely to secure funding for the organization, the OR (95%CI) was 3.42 (1.65-7.10); Social network and the core members from high endemic areas were significantly correlated with the number of HIV/AIDS patients, the OR (95%CI) were 2.79 (1.27-6.14) and 1.99 (1.21-3.27). Conclusions: We should use the core members' social network to establish relationship and communication with organizations and institutions, ultimately accelerating the growth of HIV/AIDS prevention and care.

Stretched graded-index multimode optical fiber as a saturable absorber for erbium-doped fiber laser mode locking

A novel mode-locking method based on the nonlinear multimode interference in the stretched graded-index multimode optical fiber (GIMF) is proposed in this Letter. The simple device geometry, where the light is coupled in and out of the stretched GIMF via single-mode fibers, is demonstrated to exhibit the temporal intensity discrimination required for mode locking. The nonlinear saturable absorber (SA) characteristics of the device are controllable by simply adjusting the strength of the stretching applied. The modulation depth of the device, which consists of ∼23.5  cm GIMF, is tuned from 10.37% to 22.27%. Such a simple SA enables the wavelength-switchable mode-locking operation in a ring Er-doped fiber laser, and ultrafast pulses with a pulse width of 506 fs at 1572.5 nm and 416 fs at 1591.4 nm were generated. The versatility and simplicity of the SA device, together with the possibility of scaling the pulse energy, make it highly attractive in ultrafast photonics.

Fiber in-line Mach-Zehnder interferometer based on a pair of short sections of waveguide

A fiber in-line Mach-Zehnder interferometer based on a pair of femtosecond laser inscribed short sections of waveguide is presented. One short waveguide directs part of the propagating light from the fiber core to the cladding-air interface, and experiences multiple total internal reflections before taking back to the fiber core by the other short waveguide. The device is robust in structure, can be fabricated in a fast way and with a flexible manner, and has the capability of ambient refractive index sensing, which makes it highly desirable for many "lab-in-fiber" applications.

Saturable absorber based on a single mode fiber - graded index fiber - single mode fiber structure with inner micro-cavity

An Er-doped mode-locked fiber laser with a saturable absorber based on single mode - graded index multimode - single mode fiber (SMF-GIMF-SMF) with inner micro-cavity is demonstrated. The modulation depth of the saturable absorber was measured to be 1.9% when the SMF-GIMF-SMF structure is bent to a certain state. Such a simple saturable absorber enables the mode-locking operation in a ring Er-doped fiber laser and ultrafast pulses with pulse energy of 0.026 nJ and pulse width of 528 fs at the fundamental repetition rate of 14.34 MHz can be generated. In addition, the harmonic mode-locking operation can also be achieved.

Fiber inline Mach-Zehnder interferometer based on femtosecond laser inscribed waveguides

A new type of Mach-Zehnder interferometer device based on in-fiber optical waveguides, fabricated by direct femtosecond laser pulse inscription in a single-mode fiber has been demonstrated and successfully employed for temperature and strain measurement. The in-fiber waveguide can couple the light out from the fiber core and guide it along the cladding region before directing it back into the fiber core. Such an inner structured interferometer device is compact and robust, can be constructed in a flexible and precisely controlled manner, and hence is expected to have many potential applications.

[The implantation of Bonebridge in bilateral congenital malformation of external and middle ear]

Objective: To evaluate the auditory efficacy of Bonebridge implantation in patients with bilateral congenital malformation of external and middle ear. Methods: Eleven cases (6 males and 5 females) had unilateral Bonebridge implantation. The age ranged from 8 to 26 and the average age was 16.9. Seven to ten days after operation, the first fitting was undergone. In acoustic sound field, the average auditory thresholds were respectively measured for unaided ears and Bonebridge implanted ears by pure tone auditory (PTA, 0.25, 0.5, 1, 2 and 4 kHz). For the group over 12-year-old, MSTM was applied to evaluate speech discrimination score (SDS). For the other cases, MLNT was used as the test material. The auditory efficacy post Bonebridge implantation would be analyzed and evaluated by comparing the differences between unaided ears and Bonebridge implanted ears. Results: The bone conduction audibility threshold after Bonebridge implantation was as well as the preoperative. The auditory threshold with Bonebridge aided was improved to 25-35 dB HL, when compared to that of the unaided ears in the sound field. The SDS in the group over 12-year-old was improved about 50%; the efficacy was slightly limited for the other two cases (both less than 12 years old). Statistical analysis showed that there were significant differences between unaided ears and Bonebridge implanted ears in the sound field and SDS(P<0.05). Conclusions: The auditory efficacy of Bonebridge is significant and noticeable in patients with bilateral congenital malformation of external and middle ear. Bonebridge provides a new and effective way for patient with congenital malformation of external and middle ear to reconstruct hearing.

Hybrid Fabry-Perot interferometer for simultaneous liquid refractive index and temperature measurement

A compact and high sensitivity sensor with a fiber-tip structure is proposed and demonstrated for simultaneously liquid refractive index (RI) and temperature sensing. The device is fabricated by inserting a tiny segment of capillary tube between single-mode fibers (SMFs) to form two cascaded Fabry-Perot interferometers (FPIs). The theoretical and experimental results demonstrate that the ambient liquid RI and temperature can be simultaneously determined by the intensity and shift of the resonant wavelength in the reflection spectrum. Our proposed device has the highest RI sensitivity of ~216.37 dB/RIU at the RI value of 1.30; a high spatial resolution owing to its compact size (with dimension <400 μm) makes it promising for high precision bio/chemical sensing applications.

[Vibrant soundbridge implantation of congenital atresia of oval window(with summary of nine cases]

Objective:To investigate the surgical effects of round window implantation of vibrant soundbridge(VSB)for patients with congenital oval window atresia.Method:Retrospectively analyze the clinical information of 9 cases of congenital oval window atresia as well as the pre-and post-operative hearing and speech results. Three of them had undergone or attempted the vestibulotomy but obtained poor results. All cases underwent round window implantation of VSB. Result:All patients obtained an improvement of 21-33 dBHL after implantation. In the speech recognition rate test, the average increase of disyllabic words was 62%, and 60% in the sentence test. During the follow-up of 51 months in average, 2 cases had a decline of auditory benefit and finally 1 case regained the improvement after reoperation. Conclusion:Round window implantation can get a fairly good result in congenital oval windows atresia cases.

Multimode fiber tip Fabry-Perot cavity for highly sensitive pressure measurement

We demonstrate an optical Fabry-Perot interferometer fiber tip sensor based on an etched end of multimode fiber filled with ultraviolet adhesive. The fiber device is miniature (with diameter of less than 60 μm), robust and low cost, in a convenient reflection mode of operation, and has a very high gas pressure sensitivity of −40.94 nm/MPa, a large temperature sensitivity of 213 pm/°C within the range from 55 to 85 °C, and a relatively low temperature cross-sensitivity of 5.2 kPa/°C. This device has a high potential in monitoring environment of high pressure.

Six-Transmembrane Epithelial Antigen of Prostate 1 (STEAP1) Has a Single b Heme and Is Capable of Reducing Metal Ion Complexes and Oxygen

STEAP1, six-transmembrane epithelial antigen of prostate member 1, is strongly expressed in several types of cancer cells, particularly in prostate cancer, and inhibition of its expression reduces the rate of tumor cell proliferation. However, the physiological function of STEAP1 remains unknown. Here for the first time, we purified a mammalian (rabbit) STEAP1 at a milligram level, permitting its high-quality biochemical and biophysical characterizations. We found that STEAP1 likely assembles as a homotrimer and forms a heterotrimer when co-expressed with STEAP2. Each STEAP1 protomer binds one heme prosthetic group that is mainly low-spin with a pair of histidine axial ligands, with small portions of high-spin and P450-type heme. In its ferrous state, STEAP1 is capable of reducing transition metal ion complexes of Fe³⁺ and Cu²⁺. Ferrous STEAP1 also reacts readily with O₂ through an outer sphere redox mechanism. Kinetics with all three substrates are biphasic with ∼80 and ∼20% for the fast and slow phases, respectively, in line with its heme heterogeneity. STEAP1 retained a low level of bound FAD during purification, and the binding equilibrium constant, K_D, was ∼30 μM. These results highlight STEAP as a novel metal reductase and superoxide synthase and establish a solid basis for further research into understanding how STEAP1 activities may affect cancer progression.

An Aromatic Cap Seals the Substrate Binding Site in an ECF-Type S Subunit for Riboflavin

ECF transporters are a family of active membrane transporters for essential micronutrients, such as vitamins and trace metals. Found exclusively in archaea and bacteria, these transporters are composed of four subunits: an integral membrane substrate-binding subunit (EcfS), a transmembrane coupling subunit (EcfT), and two ATP-binding cassette ATPases (EcfA and EcfA'). We have characterized the structural basis of substrate binding by the EcfS subunit for riboflavin from Thermotoga maritima, TmRibU. TmRibU binds riboflavin with high affinity, and the protein-substrate complex is exceptionally stable in solution. The crystal structure of riboflavin-bound TmRibU reveals an electronegative binding pocket at the extracellular surface in which the substrate is completely buried. Analysis of the intermolecular contacts indicates that nearly every available substrate hydrogen bond is satisfied. A conserved aromatic residue at the extracellular end of TM5, Tyr130, caps the binding site to generate a substrate-bound, occluded state, and non-conservative mutation of Tyr130 reduces the stability of this conformation. Using a novel fluorescence binding assay, we find that an aromatic residue at this position is essential for high-affinity substrate binding. Comparison with other S subunit structures suggests that TM5 and Loop5-6 contain a dynamic, conserved motif that plays a key role in gating substrate entry and release by S subunits of ECF transporters.

Sagnac interferometer hydrogen sensor based on panda fiber with Pt-loaded WO3/SiO2 coating

A highly sensitive optical fiber Sagnac interferometer hydrogen sensor is proposed and demonstrated. The device is fabricated by inserting a segment of panda fiber coated with Pt-loaded WO₃/SiO₂ into a Sagnac interferometer loop. When Pt/WO₃ film is exposed to hydrogen, the exothermic reaction raises the temperature of the panda fiber, resulting in the resonant wavelength shift of the interferometer, and the resonant dip obtained has a large extinction ratio of ∼25  dB and a narrow linewidth of 2.5 nm. Such a device responds fast to hydrogen, exhibits a high sensitivity of -7.877  nm/% (vol. %) within the range of 0%-1.0% and is robust, low cost, and easy to fabricate.