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Er-doped optical fiber (EDF) with ultra-broad gain bandwidth is urgently needed given the rapid advancement of optical communication. However, the weak crystal field of the host silica glass severely restricts the bandwidth of traditional EDF at 1.5 μm. In this study, we theoretically explored the introduction of PbS nanomaterials in the silica network assisted with the non-bridging oxygen. This can significantly increase the crystal field strength of Er3+ ions in the local structure, leading to their energy level splitting and expanding the fluorescence bandwidth. Additionally, the PbS/Er co-doped optical fiber (PEDF) with improved fluorescence and gain characteristics was fabricated using modified chemical vapor deposition combined with the atomic layer deposition technique. The presence of PbS nanomaterials in the fiber core region, which had an average size of 4 nm, causes the 4I13/2 energy level of Er3+ ions to divide, increasing the fluorescence bandwidth from 32 to 39 nm. Notably, the gain bandwidth of PEDF greater than 20 dB increased by approximately 12 nm compared to that of EDF. The obtained PEDF would play an important role in the optical fiber amplifier and laser applications. [ABSTRACT FROM AUTHOR]

• An optical fiber weak magnetic sensing system based on Michelson interferometer is proposed. • A new improved phase-generated carrier demodulation algorithm. • Suitable for optical fiber interference weak signal demodulation. • The sensing unit support frame was fabricated using 3D printing. The detection of weak magnetic fields is integral to applications in geophysical monitoring, biomagnetism, and remote sensing. This paper presents a new sensing unit structure and signal demodulation algorithm for optical fiber weak magnetic sensing system. The system uses a strip-ring sensing unit structure that combines magnetostrictive effects with optical fibers through 3D printing technology. This integration facilitates the conversion of magnetostrictive displacement into optical phase. An improved Phase Generated Carrier (PGC) algorithm is employed to demodulate the phase information, enhancing the signal to noise ratio (SNR) by 4.33 dB compared to the traditional PGC algorithm, and achieving a phase resolution of 29.51 µrad/Hz1/2 at 500 Hz. Experimental results demonstrate that the suggested sensing system can detect a minimum magnetic field of 140 nT, with an AC magnetic field phase resolution of 15.78 nT/Hz1/2 at 500 Hz. The demodulation sensitivity reaches 1.87 × 10−6 rad/nT under a magnetic field of 140–1400 nT. The capability of the proposed system demonstrated great potential as an efficient approach for detecting weak magnetic signals in many practical applications. [ABSTRACT FROM AUTHOR]

• The local structure models of PbS/PbSe co-doped fiber materials are built based on density functional theory. • PbS/PbSe nano-semiconductor co-doped silica fiber exhibites broadband luminescence enhancement at 1000–1380 nm and achieved a net gain of 14.5 dB at 1160 nm. • PbSe co-doping improves the deposition environment of PbS and increases the density distribution of nanoparticles. A PbS/PbSe nano-semiconductor co-doped silica fiber (PbS/PbSe DSF) was prepared and the enhancement mechanism of fluorescence and gain characteristics were investigated. PbS/PbSe DSF showed the broadband luminescence ranging from 1000 nm to 1380 nm, and the fluorescence intensity at 1160 nm and 1300 nm was enhanced by 15.8 dB and 14.6 dB, respectively. The on–off gain of PbS/PbSe DSF is 13.7–18.9 dB in the range of 1100–1350 nm and the net gain is 10.7–14.5 dB under 980 nm pumping. Simultaneously, based on density functional theory (DFT), local structural models of PbS/PbSe co-doped fiber materials were built, and the study showed that the introduction of PbSe increased the absorption at 969 nm and the corresponding emission in the range of 1100–1400 nm. Moreover, microstructural characterization showed the presence of high-density nanoparticle distribution in the core of PbS/PbSe DSF, indicating that the PbSe co-doping may have changed the local field environment of PbS deposition and increased the crystallinity, which finally improved the fiber performance. The results indicate that the proposed PbS/PbSe DSF is a potential gain material with important research value in areas such as active fiber amplifiers. [ABSTRACT FROM AUTHOR]

A novel nanoparticles-quantum dots-based fluorescence sensor array has been developed for sensing proteins and cancer cells. In this study, six types of nanoparticles (NPs, including CuO, ZnO, Eu 2 O 3 , AuNPs, AgNPs, Au-Ag core-shell） conjugated with CdSe quantum dots (QDs) were used as sensing elements to create the multi-sensors of array. The fluorescence of quantum dots was efficiently quenched by nanoparticles. Fluorescence turn-on or further quenching could be observed due to the disruption of the nanoparticles-QDs interaction by proteins, affording distinct fluorescence response patterns. Linear discriminant analysis (LDA) was used to analyze the patterns. Moreover, protein quantification could be performed according to the fluorescence intensity on a specific or single sensing element. The linear dynamic ranges of the sensor array for proteins was in the range of 2–50 μM, and the limits of detection (LODs) was below 2 μM that varied for different proteins. Six cancer cells were also successfully differentiated by their fluorescence response patterns. This work indicates that the nanoparticles-QDs-based sensor array has a great potentials to be used in such fields as proteomics and medical diagnostics. [ABSTRACT FROM AUTHOR]

The effect of heat treatment on the optical properties of a PbS-doped silica optical fibre was investigated. The experimental results showed that the absorption peak of the fibre red shifted from 1032 to 1133 nm when the heat treatment temperatures were carried out at 900, 950, 1000, and 1100 °C for 1 h, respectively. At the same time, when the heat treatment at 900 °C was carried out for 2, 5, 10, 20, and 40 h, the absorption spectra of the fibre showed a red shift from 1074 to 1143 nm. In addition, the intensity of the absorption peak increased from 0.258 to 1.384 dB/m and the full width at half maximum (FWHM) became narrower (from 130 to 50 nm) as the heat treatment proceeded. Moreover, the photoluminescence (PL) intensity in the wavelength range of 1100–1500 nm decreased with an increase in the heat treatment temperature. The theoretical analysis, using an effective mass method, showed that the effective band gap energy and average size of the lead sulphide (PbS) quantum dots (QDs) in the silica fibre core varied from 1.199 to 1.083 eV and from 4.28 to 4.81 nm, respectively. The results indicate that the size of the PbS QDs present in the silica fibre core could be controlled by a proper heat treatment, which is of great interest in optical fibre amplifiers and other fibre optic devices. [ABSTRACT FROM AUTHOR]

Due to the significant advancement of transmission networks and related technologies, optical communication with a large capacity is essential. In this study, a few-mode PbS quantum dot-doped fibre amplifier (FM-PQDFA) was developed and numerically studied. The amplifier can effectively amplify the linear polarisation (LP) signal modes, including LP 01 , LP 11 , and LP 21 , in the range 1100–1350 nm. The influences of the quantum dot (QD) doping concentration, fibre length, and signal power on the gain and noise figure (NF) of FM-PQDFA were investigated. In addition, the pump influenced the gain, NF, and differential mode gain (DMG). The results revealed that the gain, NF, and DMG can be optimised by adopting an appropriate pump light mode. When the signal and pump light modes were both LP 01 , the highest gain of 31.6 dB and lowest NF of 3.25 dB were achieved. LP 11 pump mode was the optimal pumping mode to obtain the high gain, low NF and small DMG simultaneously. • A low-noise broadband few-mode PbS quantum dots-doped fibre amplifier was proposed and numerically analysed. It can amplify LP 01,s and LP 11,s evenly in the band ranging from 1136–1316 nm. The gains were higher than 27 dB, the DMG was less than 1 dB and the NFs were lower than 3.35 dB. • The QD doping concentration, fibre length, and signal power are important parameters that affect the performance of FM-PQDFA. • The pump influenced the gain, NF, and differential mode gain (DMG) by affecting the overlap factor between the pump light mode field, signal light mode field, and the area of the doped material; and the gain, NF, and DMG can be optimised by adopting an appropriate pump light mode. • When the signal and pump light modes were both LP 01 , the highest gain of 31.6 dB and lowest NF of 3.25 dB were achieved. [ABSTRACT FROM AUTHOR]

Herein we report a novel strategy for the detection and identification of proteins using unmodified noble metal nanoparticles. Five gold nanoparticles (AuNPs) and two silver nanoparticles (AgNPs) with different sizes were utilized as sensing elements to create a colorimetric sensor array. In the presence of proteins, the UV-vis absorbance of the noble metal nanoparticles changed due to the interactions between the protein and nanoparticles, producing distinct absorbance response patterns which can be visually detected by the naked eye. The color pattern of the array is a unique “fingerprints” for each protein sample, which can be differentiated by linear discriminant analysis (LDA). Ten different proteins at concentrations of 0.5, 5 and 50 μM have be successfully discriminated. Moreover, the array was also able to discriminate different bacteria at a concentration of 0.05 OD in 200 μL, as well as cancer cells at the level of 5000 cells in 200 μL. This work demonstrates that an unmodified noble metal nanoparticle-based protein detection array has potential for applications in medical diagnostics. [ABSTRACT FROM AUTHOR]

Optical properties of PbS-doped silica optical fiber materials and theoretical simulation are investigated. PbS is deposited on silica optical fiber materials by Atomic Layer Deposition (ALD) technique with Pb(tmhd) 2 and H 2 S as Pb and S precursors, respectively. Its stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence states of S and Pb element are −2 and +2, respectively. The Raman spectra further reveal that PbS has been doped into optical fiber materials almost without destroying irregular rings structure in silica material network. And there are distinct absorption bands at 248 and 352 nm. Fluorescence spectra are obtained with 330 and 350 nm pumping, two fluorescence peaks at 768 and 808 nm, respectively. In addition, the microstructure models for PbS-doped optical fiber materials are built on Gaussian09 platform, and its optical properties of the absorption and emission spectra are calculated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. There are obvious absorption and emission peaks at 325.7 and 769.8 nm, respectively, which are in good agreement with experiments. [ABSTRACT FROM AUTHOR]

To study the performance of the PbS quantum dots (QDs)-doped silica fiber amplifier (PQDFA), here, a model of PQDFA with ultra-broadband gain and low noise is theoretically proposed. Based on this model, the impact of fiber structure, pump/signal power, and PbS QDs properties on the noise figure (NF) of PQDFA is investigated. The simulation results show that pump/signal light power changes the NF of PQDFA by affecting the population inversion level. Besides, the Stokes-shift and doping concentration proportion of QDs also affect the performance of fiber amplifiers. In addition, the gain and NF spectrum of single- and multi-sized PQDFA are simulated and compared. The simulation results show that the working band of PQDFA is determined by the QDs' emission spectra, and wavelength tunability can be achieved by changing the QDs' distribution in fiber. For the multi-sized PQDFA proposed in this paper, under − 10 dBm input signal power, the 3 dB bandwidth, highest gain, and lowest NF in 1300–1500 nm band are 107 nm, 29 dB, and 3.84 dB, respectively. • Theoretical model of PbS quantum dots-doped silica fiber amplifier. • Ultra-broadband gain and low noise multi-sized quantum dots-doped fiber amplifier. • The 3 dB bandwidth in 1300–1500 nm band is 107 nm. • The fluorescence lifetime and Stokes-shift affect the noise figure of amplifiers. • Gain and noise are related to the doping concentration proportion of quantum dots. [ABSTRACT FROM AUTHOR]

• The size of PbS nanocrystals varied with the increase of ALD growth cycles. • Annealing treatment was applied to PbS QDs for regulating PL characteristics. • As-prepared PbS QDs exhibited a tunable broadband wavelength range of 1000–1600 nm. • The PL lifetime variation of PbS QDs prepared by ALD technique was first reported. Lead sulfide (PbS) quantum dots (QDs) were deposited onto silica substrates by atomic layer deposition (ALD). By controlling the number of growth cycles, the average size of the PbS nanocrystals (NCs) changed from approximately 6.3 to 95.4 nm. The crystalline phase of the PbS semiconductor materials was investigated via X-ray diffraction, and it was established that as the size of the NCs increased, the preferred growth orientation of the PbS films was (2 0 0). The obtained nanofilms were compact and continuous polycrystalline films with well-defined grain boundaries. To control the size of PbS QDs further, the temperature-induced characteristics of the ALD-fabricated PbS QD films were studied through annealing. Slow growth of the PbS QDs was observed for the nanofilms annealed at temperatures below 300 °C, whereas the QD size increased significantly at annealing temperatures above 300 °C. The broad near-infrared luminescence wavelength of the PbS nanofilms was tuned from 1000 to 1600 nm. Moreover, the photoluminescence lifetime of the annealed PbS QDs increased from 4.96 to 10.92 μs. The temperature-induced and size-controlled PbS QDs are ideal materials for application in wavelength-tunable optical devices. [ABSTRACT FROM AUTHOR]

• Formation mechanisms for PbS nanomaterials grown on silica substrate are studied by DFT. • PbS are doped into the fiber core via ALD, with nanostructure confirmed by HRTEM. • PbS-doped fiber exhibits fluorescence property at 1060–1370 nm with 1064 nm pumping. • PbS-doped fiber amplifier exhibited a signal gain as 9.4 dB at 1310 nm. The formation mechanisms for lead sulfide (PbS) semiconductor nanomaterials grown on silica substrate were investigated using density functional theory. There are two main reaction processes for the adsorption of Pb(tmhd) 2 on a silica substrate and the reaction with H 2 S to form PbS. The activation barriers of the two reaction processes were quite low at 10.1923 and 20.6778 kcal/mol, which is energetically favorable for PbS deposition by atomic layer deposition (ALD). In addition, PbS nanomaterials were introduced both on silica substrate and into the core of the silica fiber via ALD, with Pb(tmhd) 2 and H 2 S as precursors. The structural properties of the PbS nanomaterials and optical properties of the PbS-doped fiber were characterized. There were obvious absorption peaks at 480, 695, and 1043 nm. The fiber exhibited photoluminescence at 1060–1370 nm with 1064 nm pumping. A gain of 9.4 dB was obtained at 1310 nm, which can be attributed to the PbS nanomaterials in the fiber core. This is crucial for optical fiber communications. [ABSTRACT FROM AUTHOR]

Background Objective Materials and Methods Results Conclusions Temporomandibular joint disorders (TMDs) are common in young adults, and the link between chronotype profile and TMDs is unclear.This study examined TMD prevalence and chronotype distribution and explored the relationship between chronotype and TMDs in young adults.A total of 663 students from Sichuan University completed questionnaires. Chronotype profiles were assessed using the Morningness‐Eveningness Questionnaire, and TMDs were screened using the Fonseca Memory Index. To validate the findings, 68 TMD patients and 136 controls were enrolled.The prevalence of TMDs was 69.7%, with significant differences among chronotype profiles. The intermediate profile was the most common chronotype. Eveningness profile was associated with higher TMDs prevalence and severity. Muscle pain and side movement difficulty scores were higher in eveningness and intermediate profiles. Female gender (OR 2.345; 95% CI 1.668–3.297) was a TMD risk factor, while morningness profile (OR 0.537; 95% CI 0.297–0.970) was protective. Validation with TMD patients and controls supported these findings, showing higher eveningness profile prevalence in the TMD groups.TMDs have a high prevalence in college students, chronotype profiles shown to be associated with TMDs. Morningness is the protection factor in TMDs and PT, eveningness is a risk factor for IT. [ABSTRACT FROM AUTHOR]

Protein identification is very important in the field of clinical medicine and diagnosis. Here, we report a novel and simple sensor array for the detection and identification of proteins using pH buffer solutions as sensing elements. Different proteins in various pH solutions have different net surface charges including positive, negative or no charge. Such differences may allow a pattern recognition-based sensor array for protein identification. When using negatively charged CdSe/ZnS quantum dots as an indicator, the interactions between a charged protein and quantum dots result in fluorescence changes, generating a differential response pattern for the protein. The result shows that proteins with pI ＞ 7, pI = 7 or pI ＜ 7 can be differentiated successfully. Moreover, complex protein mixtures are also able to be identified and the results demonstrate that surface charge may play an important role in protein sensing. The HSA of different concentrations in water and human urine can also be detected by using the sensor array. It is demonstrated that the proposed sensor array has potential applications in clinical diagnosis and proteomics. [ABSTRACT FROM AUTHOR]

We report a simple and novel colorimetric sensor array for rapid identification of microorganisms. In this study, four gold nanoparticles (AuNPs) with diverse surface charges were used as sensing elements. The interactions between AuNPs and microorganisms led to obvious color shifts, which could be observed by the naked eye. A total of 15 microorganisms had their own response patterns and were differentiated by linear discriminant analysis (LDA) successfully. Moreover, microorganism mixtures could also be well discerned. The method is simple, fast (within 5 s), effective, and visual, showing the potential applications in pathogen diagnosis and environmental monitoring. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess the epidemiological features and explore the potential risk factors for early neurological deterioration (END) in patients with acute single small subcortical infarction (SSSI) who underwent antiplatelet therapy without carotid artery stenosis. Materials & methods: Patients with SSSI, as confirmed by cranial magnetic resonance imaging (MRI), who were hospitalized within 48 h after the onset of symptoms were enrolled. END was mainly defined as increment in the National Institutes of Health Stroke Scale (NIHSS) score of ≥ 2 points or any new neurological deficit. Poor functional outcome was defined as modified Rankin Scale (mRS) score of > 2 points at 3-month after the onset. The association of END with multiple indicators was assessed at the early stage of admission using multivariate logistic regression analysis, and adjusted odds ratios (aORs) were calculated. Results: A total of 280 patients were enrolled from June 2020 to May 2021, of whom, END occurred in 44 (15.7%) patients (median age, 64 years; 70.5% male), while END occurred during sleep in 28 (63.6%) patients. History of hypertension (aOR: 4.82, p = 0.001), infarction in internal capsule (aOR: 3.35, p = 0.001), and elevated level of low-density lipoprotein cholesterol (LDL-C; aOR: 0.036, p = 0.0016) were significantly associated with the risk of END. Patients with END (aOR: 5.74, p = 0.002), history of diabetes (aOR: 2.61, p = 0.020), and higher NIHSS scores at discharge (per 1-score increase, aOR: 1.29, p = 0.026) were associated with the poor functional outcome at 3-month after the onset. Conclusion: Patients with a history of hypertension, infarction in internal capsule or a higher level of LDL-C were found to be at a higher risk of END. [ABSTRACT FROM AUTHOR]

A semiconductor PbS quantum-dots-doped is fabricated using modified chemical vapour deposition in combination with atomic layer deposition. Its photoluminescence properties and unsaturable absorption loss are analysed. It exhibits distinct absorption peaks at 586, 738, and 1048 nm and broadband luminescence in the range 1100–1300 nm. Its full-wave at half-maximum (FWHM) is approximately 130 nm, and its saturable and unsaturable absorption values at 980 nm are 3.82 and 0.75 dB/m, respectively. Furthermore, its figure of merit pump absorption is approximately 83.6%. This is a high, useful pump absorption, and this fibre may be used for novel active optical fibre materials. [ABSTRACT FROM AUTHOR]

The Bi/Al-codoped silica optical fibers are fabricated by atomic layer deposition (ALD) doping technique combing with conventional modified chemical vapor deposition (MCVD) process. Bi 2 O 3 and Al 2 O 3 are induced into silica optical fiber core layer by ALD technique, with Bis (2,2,6,6-tetra-methyl-3,5-heptanedionato) Bismuth(III) (Bi(thd) 3 ) and H 2 O as Bi and O precursors, and with Al(CH 3 ) 3 (TMA) as Al precursor, respectively. The structure features and optical properties of Bi/Al-codoped silica optical fibers are investigated. Bi 2 O 3 stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence state of Bi element is +3. Concentration distribution of Si, Ge and O elements is approximately 24–33, 9 and 66 mol%, respectively, in fiber preform core and cladding layer region. Bi and Al ions have been also slightly doped approximately 150–180 and 350–750 ppm in fiber preform core, respectively. Refractive index difference of the Bi/Al-codoped fiber is approximately 0.58% using optical fiber refractive index profiler analyzer. There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. The fluorescence peaks are at 1130 and 1145 nm with 489 and 705 nm excitations, respectively. Their fluorescence lifetimes are 701 and 721 μs, respectively. And then there are obvious fluorescence bands in 600–850 and 900–1650 nm with 532 nm pump exciting. There is a maximum fluorescence intensity peak at 1120 nm, and its full wave at half maximum (FWHM) is approximately 180 nm. These may mainly result from the interaction between Bi and Al ions. The Bi/Al-codoped silica optical fibers would be used in high power or broadly tunable laser sources, and optical fiber amplifier in the optical communication fields. [ABSTRACT FROM AUTHOR]

Abstract: A novel method was designed for the determination of trace protein with high sensitivity. This sensing method combined the principle of biomineralization and the resonance scattering (RLS) assay of gold nanoparticles (AuNPs). AuNPs were synthesized in the presence of polpyropylneimine hexadeacamnie dendrimers (PPIHA). Meanwhile, they were superficially modified with the amine group, which was confirmed by Fourier transform infrared spectra (FTIR). The specific covalent coupling between bovine serum albumin (BSA) and amine-AuNPs assembles a hyperefficient crystal core. Based on the principle of biomineralization, Au3+ ions were reduced to Au at the surface of bioconjugates in the HAuCl4–NH4OH·HCl redox system. Thus, the size of AuNPs–BSA was selectively enhanced. Meanwhile, the concentration signal of BSA was converted to the RLS intensity of AuNPs, which was enhanced through this process. The selective amplification of RLS signal laid the foundation of the detection method, as it intensified with the increase of AuNPs–BSA concentration. Experimental results show that the peak intensity at 548nm is proportional to the concentration gradient of the bioconjugates from 0.268μg/ml to 1.608μg/ml under the optimized conditions. Additionally, the method has high sensitivity with detection limit as low as 0.096μg/ml. The specific coupling with high sensitivity and good stability of this method indicates its possibility for the assay of other proteins. Moreover, the novel method achieves quantitative detection of trace proteins, suggesting the potential of AuNPs-based analytical methods in further application. [Copyright &y& Elsevier]

Sensitive and rapid identification of pathogenic microorganisms is of great importance for clinical diagnosis and treatment. In this study, we developed an ultrasensitive colorimetric sensor array (CSA) based on the interactions between aminoglycoside antibiotics (AMGs) and Ag nanoparticles decorated with β-cyclodextrin (AgNPs@β-CD) to discriminate microorganisms quickly and accurately. Microorganisms can absorb different amounts of AMGs after incubation. Upon the addition of AgNPs@β-CD, the corresponding extracellular AMG residues will bind to AgNPs@β-CD, leading to color changes due to the modifications in localized surface plasmon resonance. The array was developed using 4 AMGs as sensing elements and AgNPs@β-CD as the colorimetric probe to generate a unique colorimetric response pattern for each microorganism. Standard chemometric methods indicated excellent discrimination among 20 microorganisms at low concentrations of 2 × 106 CFU/mL. Therefore, this ultrasensitive CSA can be used for microbial discrimination portably and efficiently. Importantly, the concentration of microbial discrimination by our array is much lower than that of prior CSAs. This method of extracellular residue sensing also provided a new strategy to improve the sensitivity of conventional CSA in the discrimination of microorganisms, to measure the amount of intercellular uptake of AMGs by microorganisms, and to screen drugs that can easily be accumulated by the pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

We fabricated a novel Pb/Bi co-doped silica optical fiber using an atomic layer deposition technique in conjunction with a modified chemical vapour deposition process. The fabricated fiber exhibits distinct absorption peaks at 690, 800, 1000 and 1377 nm. An ultra-broad luminescence band with a 10 dB bandwidth of 600 nm from 1050 nm to 1650 nm was achieved using a dual pumps system. The lifetime of the co-doped fiber at 1150 nm is approximately 740 μs. Additionally, a Pb/Bi co-doped fiber with a length of only 0.2 m, pumped at 980 nm exhibits an optical gain ranging from 1010 to 1190 nm with a maximum peak gain of 12 dB. A theoretical model considering the interaction between Pb and Bi ions is proposed to interpret the observed spectral characteristics. There may be a coupling effect and/or energy transfer between Pb and Bi ions during a deleterious non-radiative quenching process. The Pb/Bi co-doped fiber offers a number of advantages compared to a conventional Bi-doped fiber in terms of broadband luminesce, fluorescence lifetime, and gain. Additionally, it can act as a super fluorescence fiber sources for optical amplifiers and novel fiber lasers in the medical and communication fields. • A novel Pb/Bi co-doped silica optical fiber is fabricated using an atomic layer deposition doping technique. • The 10 dB luminescence bandwidth of Pb/Bi co-doped silica optical fiber is up to 600 nm. • A Pb/Bi co-doped fiber with 0.2 m length shows the optical gain is up to 12 dB range from 1010 to 1190 nm. • A theoretical model is proposed to elucidate the effect of the introduction of Pb ions on Bi-doped fiber. [ABSTRACT FROM AUTHOR]

Integrated atomistic and molecular dynamic simulations are used to characterize the role hydrogen bonding and interchain interactions on structures and phase transitions of novel bent-core-like mesogenic materials that exhibit new self-assembly features, attractive to the development of functional materials. Multi-step simulations were carried out to model phase transitions and various spectra of two complex mesogenic materials formed from acid functionalized azo compounds, 4-[2,3,4-tri(octyloxy)phenylazo] benzoic acid and 4-[2,3,4- tri(heptyloxy)phenylazo] benzoic acid. The simulations contain three consecutive steps, involving molecular quantum chemistry, molecular crystal packing, and super cell molecular dynamics calculations. These two mesogens are supposed to form phasmidic molecular conformers. However, simulations point to the formation of complex discotic bent-core-like liquid crystals with tetramer mesogenic assemblies, in very good agreement with experimental observations. The wide range agreements between simulations and experimental results include transitions of crystal structures to columnar and uniaxial nematic phases, x-ray diffraction patterns of columnar phases, the structure of the two-dimensional complex bent-core-like tetramers, molecular Raman spectra, Raman depolarization spectra, and order parameters of nematic phases. The multi-step simulation methodology and its results shed light on this unique behaviour of plasmids with flexible side chains for simulation design of novel bent-core-like mesogenic materials. [ABSTRACT FROM AUTHOR]

Background: Obesity is a metabolic imbalance characterized by excessive deposition of white fat. The browning of white fat can effectively treat obesity and related diseases. Although Dlgap1 (Discs, Large (Drosophila) Homolog-Associated Protein 1) is suspected to have an effect on this process, no empirical evidence is available. Methods: To understand the role of Dlgap1, we cultured white and brown fat cells, then performed overexpression and knockout experiments. Results: We found that Dlgap1 overexpression in brown adipocytes inhibits brown-fat-related gene expression, promotes white-fat-related genes, while also increasing brown-adipocyte proliferation and apoptosis. However, the gene overexpression has no effect on brown adipocyte maturation. Knocking out Dlgap1 in white fat cells promotes the expression and inhibition of brown-fat-related and white-fat-related genes, respectively. Additionally, the knockout inhibits white fat cell proliferation and apoptosis, while also promoting their maturation. Conclusions: Dlgap1 negatively regulates the browning of white adipocytes by influencing cell proliferation and apoptosis. [ABSTRACT FROM AUTHOR]

• We theoretically propose a type of ring-core quantum dots doped fiber amplifier (QDFA), capable of providing amplification for a number of LP signal modes. • The annular optical fiber doped with PbS quantum dots not only supports transmission for LP (L=0∼6,1) signal mode group, but also provides relatively uniform gain for LP (L=1∼3,1) signal mode over the wavelength range 1500 nm–1630 nm. • For LP (1,1) , LP (2,1) and LP (3,1) signal modes, we explore the differential modal gain (DMG) under 11 pump mode groups (LP (L=0∼10,1)). • Noticing that the highest gain for LP (1,1) signal mode is about 31 dB obtained at the wavelength of 1530 nm and the DMG is less than 0.5 dB with a LP (7,1) pumping mode. Optical fiber amplifier is a vital device in optical communication system, which can directly amplify optical signal. We theoretically propose a type of few-mode quantum dots-doped fiber amplifier (FM-QDFA) in this paper, capable of providing amplification for a number of linear polarization (LP) signal mode groups. The main part of the amplifier is a ring-core fiber doped with PbS quantum dots. And refractive index difference between the annular area and cladding is set to 0.035, which weakens the modal coupling between different LP mode groups. The simulation results show that the ring-core optical fiber not only supports transmission for LP (L=0∼6,1) signal mode group, but also provides relatively uniform gain for LP (L=1∼3,1) signal mode group across the wavelength band 1500 nm–1630 nm that covers the C + L band. For these three signal modes, we explore the differential modal gain (DMG) under 11 pump mode groups (LP (L=0∼10,1)). Noticing that the highest gain for LP (1,1) signal mode is approximately 31 dB obtained at the wavelength of 1530 nm and the DMG is less than 0.5 dB with a LP (7,1) pumping mode. [ABSTRACT FROM AUTHOR]

The genome editors CRISPR/Cas9 (clustered regularly interspaced short palindromicrepeats/Cas9 nuclease-null) and TALENs (transcription activator-like effector nuclease) are popularly used for targeted modification of the mammalian genome. To date, few comparative studies have been carried out to investigate the differences between the use of CRISPR/Cas9 and TALENs in genome editing for goat breeding. Here, we compared CRISPR/Cas9 and TALEN technologies at multiple levels for generating a knock out (KO) of the Alpas cashmere goat myostatin (MSTN) gene, which negatively regulates the proliferation and differentiation of skeletal muscle cells. The electrotransfection efficiency observed using CRISPR/Cas9 was 8.1% more than that observed using TALEN for generating MSTN KO cells. In addition, the cutting efficiency of CRISPR/Cas9 for editing exon 1 of the MSTN gene was higher than that of TALENs. However, the off-target effects of the CRISPR/Cas9 system were also higher than those of TALENs. Further, we found that the frequency of obtaining MSTN −/- mutations by CRISPR/Cas9 was 8.5 times higher than that by TALEN. The CRISPR/Cas9-edited colonies involved longer deletions (up to 117 bp) than the TALEN-edited colonies (up to 13 bp). Remarkably, when embryos used to generate cloned goat via somatic cell nuclear transfer were compared, we found that the TALEN MSTN KO embryos easily developed to 8 cells and their cleavage rate was significantly higher than that of CRISPR/Cas9-edited embryos. Finally, we produced a MSTN KO lamb using CRISPR/Cas9, which suggested that a high level of targeted gene modification could be achieved in goat using CRISPR/Cas9. Taken together, our study indicates that although TALEN enables a variety of genome modifications and may have some advantages over CRISPR/Cas9, the latter provides a significant advantage by permitting precise and efficient gene editing. Thus, CRISPR/Cas9 has more potential to become a robust gene-engineering tool for application in the breeding of farm animals. • We successfully generated an MSTN KO lamb using CRISPR/Cas9. • We compared utility of CRISPR/Cas9 and TALEN for generating Alpas cashmere goats with myostatin (MSTN) gene knockout (KO). • Compared with CRISPR/Cas9 embryos, TALEN MSTN KO embryos reached 8-cell stage at significantly higher cleavage rate. • Compared with TALEN, CRISPR/Cas9 showed greater gene editing efficiency, but with higher number of off-target effects. • CRISPR/Cas9 has high potential to become a robust gene-engineering tool for application farm animal breeding. [ABSTRACT FROM AUTHOR]

Abstract Digital holographic tomography (DHT) technology is efficiently utilized to measure optical fiber structure profile. A Mach-Zender off-axis holographic interferometer is used to get fiber wavefront, an angular spectrum reconstruction algorithm is applied to obtain optical path difference (OPD) curves. With an adaptive simultaneous algebraic reconstruction technique (ASART), we obtain a fiber refractive index profile and non-circularity. In fiber wavefront measuring, errors are inevitably caused by measurement accuracy and fiber position offset as fiber rotating. In order to improve fiber structure profile reconstruction accuracy, we propose a novel algorithm to eliminate measuring errors of OPD curves including value drift and position drift, which obviously improves the reconstruction quality. With ASART, we analyze the structure parameters of single-mode spun fiber with various spinning pitches, including refractive index profiles and the fiber non-circularity. The results show that as the shortening of fiber spinning pitch, the refractive index dip in the fiber core is deeper and both cladding non-circularity and core non-circularity are less. [ABSTRACT FROM AUTHOR]

Multi-level theory simulations have been performed to model a number of important molecular properties of a bent-core nematic liquid crystal (LC) A131. These important properties include molecular conformations, molecular Raman spectra, differential polarisability ratios, molecular crystals packing, atomic LC structures, order parameters, and Raman depolarisation spectra. The simulations contain four theory levels, involving molecular quantum chemistry, molecular crystal packing, super cell density functional based tight binding optimisation, and super cell molecular dynamics calculations. To heat initial optimised super cell structures, molecular dynamics simulations reveal phase transitions to uniaxial and biaxial nematic phases from molecular crystals. LC atomic structures result in direct calculations on order parameters, which can be further applied to computations on Raman depolarisation spectra with differential polarisability ratios, obtained in the molecular quantum chemistry theory level. The good agreement of simulated Raman depolarisation spectra with the experiment provides a detailed analysis on the unusually low values of experimental uniaxial order parameters. [ABSTRACT FROM AUTHOR]

In active silica optical fibers, improving the solubility and uniformity of non-concentration-quenching luminescence centers is a key strategy to achieve high gain fiber amplifiers. Herein, we report a novel Er-doped silica optical fiber (EDF) modified by PbS semiconductor incorporation for the first time. Owing to the bridge role of PbS, Er 2 O 3 nanofilms deposited on the substrate via atomic layer deposition (ALD) have porous and loosely layered network structures with an increasing number of ALD-PbS layers. Subsequently, during the high-temperature fiber preparation process, this loose porous structure aids the dissolution and provides an optimal local environment of Er3+ ions in the silica matrix. As a result, the maximum phonon energy of the silica network for PbS/Er co-doped silica optical fiber (PEDF) is reduced, resulting in an increase of the Er3+ ion fluorescence lifetime, approximately 11.455 ms. Furthermore, we achieved 34 dB maximum gain of PEDF sample with the lowest noise figure of 3.9 dB at 1.5 μm. The gain bandwidth over 20 dB of PEDF is approximately 46 nm, which is nearly 44% higher than that of EDF. These results indicate that the PEDF prepared by structural manipulation has great potentials in optical fiber amplifier and laser applications. • Porous PbS/Er co-doped nanofilms were prepared and characterized. • PbS and Er co-doped silica fibers (PEDF) were fabricated for the first time. • Er3+ ions in PEDF show more uniform distribution and higher fluorescence efficiency. • PEDF has the high gain of 34 dB and low NF of 3.9 dB in the amplification system. • Gain bandwidth of PEDF are increased by 44% compared to the non-PbS doped EDF. [ABSTRACT FROM AUTHOR]

Bacterial biofilms are responsible for many chronic infections because antibacterial agents exhibit poor penetration into the dense matrix barrier and cannot easily reach the internal bacteria. Herein, we reported pH-responsive nanocomposites (PDA@Kana-AgNPs) that could penetrate and disperse biofilms, which were synthesized by the combination of ultrasmall silver nanoparticles (AgNPs) and kanamycin, and then coating with polydopamine. Confocal fluorescence imaging indicated that PDA@Kana-AgNPs could respond to the acidic microenvironment of biofilms, leading to biofilm-triggered on- demand drug release in situ. The zone of inhibition test and Resazurin assay showed that the combination of kanamycin and AgNPs had greater antimicrobial activity against test strains (Staphylococcus aureus , Streptococcus pneumoniae , Pseudomonas aeruginosa , and Escherichia coli BL21) than when applied separately. The crystal violet staining test demonstrated that biofilms were effectively dispersed by the proposed nanocomposites. Biocompatibility was also evaluated, which showed that PDA@Kana-AgNPs were non-toxic to mammalian cells. Therefore, the proposed pH-responsive nanocomposites held great potential for efficient antibiotics delivery and showed synergistic antibacterial and antibiofilm activities. This strategy could also be used to encapsulate a variety of antibiotics in combination with other drugs or materials, thereby showing therapeutic potential in preventing biofilm-related infections and realizing fluorescence imaging in situ. [Display omitted] • pH-responsive polydopamine coated AgNPs-Kana nanocomposites were prepared. • Acidic biofilm microenvironment induced AgNPs-Kana release from nanocomposites. • AgNPs-Kana exhibited synergistic antibacterial effects and antibiofilm abilities. • Nanocomposites had good biocompatibility with human blood cells. [ABSTRACT FROM AUTHOR]

Abstract: Herein, using DNA adenine methylation (Dam) methyltransferase (MTase) as a model analyte, a simple, rapid, and highly sensitive fluorescence sensing platform for monitoring the activity and inhibition of DNA MTase was developed on the basis of methylation-sensitive cleavage and nicking enzyme-assisted signal amplification. In the presence of Dam MTase, an elaborately designed hairpin probe was methylated. With the help of methylation-sensitive restriction endonuclease DpnI, the methylated hairpin probe could be cleaved to release a single-stranded DNA (ssDNA). Subsequently, this released ssDNA would hybridize with the molecular beacon (MB) to open its hairpin structure, resulting in the restoration of fluorescence signal as well as formation of the double-stranded recognition site for nicking enzyme Nt.BbvCI. Eventually, an amplified fluorescence signal was observed through the enzymatic recycling cleavage of MBs. Based on this unique strategy, a very low detection limit down to 0.06U/mL was achieved within a short assay time (60min) in one step, which is superior to those of most existing approaches. Owing to the specific site recognition of MTase toward its substrate, the proposed sensing system was able to readily discriminate Dam MTase from other MTase such as M.SssI and even detect the target in complex biological matrix. Furthermore, the application of the proposed sensing strategy for screening Dam MTase inhibitors was also demonstrated with satisfactory results. This novel method not only provides a promising platform for monitoring activity and inhibition of DNA MTases, but also shows great potentials in biological process researches, drugs discovery and clinical diagnostics. [Copyright &y& Elsevier]

The cerium (Ce)-doped optical fiber materials show great applications in smart lighting, fiber laser, and high-energy ray and particle detection. A major challenge is the efficient prevention of Ce3+ oxidized to Ce4+ ions. Here we report the CO 2 -laser-heated drawing method for fabricating Ce:YAG derived scintillating optical fiber with a concentration of Ce ions (0.21 wt%), and the effective atomic number is 25.4. The estimated ratio of Ce4+/ΣCe is 37% in the raw YAG ceramics, which can be effectively reduced to 3% in the fiber core because of the negative oxygen atmosphere during the fiber drawing process and the formation of non-bridging oxygen. The result is confirmed by the optical absorption spectrum, X-ray absorption fine structure spectra (XAFS), and Raman spectra. These induce a strong emission peak at 401 nm under the X-ray excitation. Moreover, the normalized integral scintillation efficiency of the Ce:YAG derived fiber is up to ~43% of that of Bi 4 Ge 3 O 12 (BGO) scintillating crystal. The Ce:YAG derived optical fiber is believed to be a promising candidate for scintillators in remote fiber-optic radiation detection applications. • Ce:YAG derived fiber was fabricated using the CO 2 -laser-heated method. • The ratio of Ce3+/Ce4+ ions in the fiber was evaluated with the XAFS. • The Ce3+ ions play an important role in the scintillation process of Ce:YAG derived fiber. • High scintillation efficiency of Ce:YAG derived fiber with the excitation of X-ray. • Significant linear RL response of Ce:YAG derived fiber for the X-rays detection. [ABSTRACT FROM AUTHOR]