Core–Shell Microfiber Encapsulation Enables Glycerol‑Free Cryopreservation of RBCs with High Hematocrit

Cryopreservation of red blood cells(RBCs)provides great potential benefits for providing transfusion timely in emergencies.High concentrations of glycerol(20%or 40%)are used for RBC cryopreservation in current clinical practice,which results in cytotoxicity and osmotic injuries that must be carefully controlled.However,existing studies on the low-glycerol cryopreservation of RBCs still suffer from the bottleneck of low hematocrit levels,which require relatively large storage space and an extra concentration process before transfusion,making it inconvenient(time-consuming,and also may cause injury and sample lose)for clinical applications.To this end,we develop a novel method for the glycerol-free cryopreservation of human RBCs with a high final hematocrit by using trehalose as the sole cryoprotectant to dehydrate RBCs and using core–shell alginate hydrogel microfibers to enhance heat transfer during cryopreservation.Different from previous studies,we achieve the cryopreservation of human RBCs at high hematocrit(>40%)with high recovery(up to 95%).Additionally,the washed RBCs post-cryopreserved are proved to maintain their morphology,mechanics,and functional properties.This may provide a nontoxic,high-efficiency,and glycerol-free approach for RBC cryopreservation,along with potential clinical transfusion benefits.

Eco-friendly aqueous foam stabilized by cellulose microfibers with great salt tolerance and high temperature resistance

A low-cost eco-friendly aqueous foam,especially the robust foam with great tolerance to high salinity and high temperature,is in great demand in the oil industry,e.g.,oil and gas well or geothermal well drilling.Herein,an ultra-stable aqueous foam was developed using the biodegradable cellulose microfiber(CMF)as a foam stabilizer.The foam stabilized by CMF shows excellent tolerance to the high concentration of NaCl(6.0 wt%)and CaCl_(2)(0.25 wt%)and the related drainage half-life times(T_(0.5))reach 1750 and 2340 s respectively.By contrast,the foams without CMF are completely drained(T_(0.5)=0 s)when NaCl concentration is greater than 6.0 wt%or CaCl_(2) concentration is greater than 0.20 wt%.Notably,T0.5 of the foams stabilized by CMF at these saline concentrations still can maintain above 1000 s even after aging at 120℃ for 16 h,exhibiting an outstanding foam-stabilizing performance at high temperature.Experimental results suggest that the salt and high-temperature tolerance of CMF in foam stabilization is attributed to the electrically uncharged surfaces,the formation of a gel-like structure and the excellent thermal stability.This work not only provides a promising candidate of aqueous foam stabilizer to deal with high temperature and high salinity but also presents a natural-based solution for an environmentally friendly drilling industry in the future.

The Study on Bamboo Microfibers Isolated by Steam Explosion and Their Comprehensive Properties

To overcome the shortage of wood resources as well as to develop novel natural fibers materials,the Chimonobambusa quadrangularis(CQ)and Qiongzhuea tumidinoda(QT)planted in Southwest China were effectively isolated by the steam explosion(SE).The fine and uniform bamboo microfibers derived from CQ and QT were obtained,and their smallest average widths were 12.62μm and 16.05μm,respectively.The effects of steam explosion on the micro-morphology,chemical composition,thermal stability,crystallinity,surface wettability,and mechanical properties of bamboo microfibers were comprehensively investigated.The results showed that the relative content of cellulose in bamboo microfibers increased but the hemicellulose and lignin contents decreased after SE.The degrees of crystallinity for CQ and QT increased from 40.49%and 39.46%to 68.90%and 55.78%,respectively.The thermal stability and surface hydrophilicity were also improved.The CQ microfibers had a maximum decomposition temperature of 2.79°C,a tensile strength of 58.54 MPa,an elongation at break of 0.6%,and a water contact angle of 2.7°higher than those of the QT microfibers.

Spatiotemporal hemodynamic monitoring via configurable skin-like microfiber Bragg grating group

Systemic blood circulation is one of life activity’s most important physiological functions.Continuous noninvasive hemodynamicmonitoring is essential for the management of cardiovascular status.However,it is difficult to achieve systemichemodynamic monitoring with the daily use of current devices due to the lack of multichannel and time-synchronized operationcapability over the whole body.Here,we utilize a soft microfiber Bragg grating group to monitor spatiotemporalhemodynamics by taking advantage of the high sensitivity,electromagnetic immunity,and great temporal synchronizationbetween multiple remote sensor nodes.A continuous systemic hemodynamic measurement technique is developedusing all-mechanical physiological signals,such as ballistocardiogram signals and pulse waves,to illustrate the actualmechanical process of blood circulation.Multiple hemodynamic parameters,such as systemic pulse transit time,heartrate,blood pressure,and peripheral resistance,are monitored using skin-like microfiber Bragg grating patches conformallyattached at different body locations.Relying on the soft microfiber Bragg grating group,the spatiotemporal hemodynamicmonitoring technique opens up new possibilities in clinical medical diagnosis and daily health management.

Broadband and continuous wave pumped second-harmonic generation from microfiber coated with layered GaSe crystal

The conversion-efficiency for second-harmonic(SH)in optical fibers is significantly limited by extremely weak second-order nonlinearity of fused silica,and pulse pump lasers with high peak power are widely employed.Here,we propose a simple strategy to efficiently realize the broadband and continuous wave(CW)pumped SH,by transferring a crystalline GaSe coating onto a microfiber with phase-matching diameter.In the experiment,high efficiency up to 0.08%W-1mm-1 is reached for a C-band pump laser.The high enough efficiency not only guarantees SH at a single frequency pumped by a CW laser,but also multi-frequencies mixing supported by three CW light sources.Moreover,broadband SH spectrum is also achieved under the pump of a superluminescent light-emitting diode source with a 79.3 nm bandwidth.The proposed scheme provides a beneficial method to the enhancement of various nonlinear parameter processes,development of quasi-monochromatic or broadband CW light sources at new wavelength regions.

Synthesis of Hyperbranched Polymers and Its Effect on Water Vapor Permeability of Microfiber Synthetic Leather

A series of hyperbranched poly(amine-ester)polyols were synthesized by the polycondensation of N,N-diethylol-3-amine-methylpropionate(prepared by Michael addition reaction of methyl acrylate with diethanolamine)as an AB2-type monomer with trimethylol propane as the core moiety,proceeding in one-step procedure in the melt with p-toluenesulfonic acid as catalyst.The obtained monomer and polymers were characterized by FTIR and 1H-NMR spectroscopy.The solubility and surface activity in aqueous solution of the polymers were also examined.The gas permeability,water vapor permeability,and moisture absorption of microfiber synthetic leather treated by hyperbranched polymer were studied.The optimum conditions were that the dosage of dye and hyperbranched polymer was 5% and 10%,respectively.The water vapor permeability and moisture absorption of microfiber synthetic leather reached to 0.525 4 mg/(10 cm2·24 h)and 0.046 7 mg/(10 cm2·24 h).Compared with blank samples,they increased by 15% and 35%,respectively.However,the dosage of hyperbranched polymer has little influence on gas permeability of microfiber synthetic leather.SEM results show that the fiber of microfiber synthetic leather treated by hyperbranched polymer is incompact.

Generation and evolution of multiple operation states in passively mode-locked thulium-doped fiber laser by using a graphene-covered-microfiber

Using graphene-covered-microfiber （GCM） as a saturable absorber, the generation and evolution of multiple operation states are proposed and demonstrated in passively mode-locked thulium-doped fiber laser. The microfiber was fabricated using the flame brushing method to an interaction length of - 1.2 cm with a waist diameter of -10 μm. Graphene layers were grown on copper foils by chemical vapor deposition and transferred onto the polydimethylsiloxane （PDMS） to form a PDMS/graphene film, which allowed light-graphene interaction via evanescent field. With the increase of the pump power from 1.25 W to 2.15 W, five different lasing regimes, including continuous-wave, conventional soliton mode-locking, multi- soliton mode-locking, a period of transition, and noise-like mode-locking, were achieved in a fiber ring cavity. To the best of our knowledge, it is the first report of the generation and evolution of multiple operation states by covering graphene on the microfiber in the 2-μ.m region. The results demonstrate that GCM can be a promising method for fabricating all fiber SA, and the switchable operation states can provide more portability in complex application domain.

Enhancement of microwave absorption of nanocomposite BaFe_(12)O_(19)/α-Fe microfibers

Nanocomposite BaFe12019/a-Fe microfibers with diameters of about 1-5 μm are prepared by the organic gel- thermal selective reduction process. The binary phase of BaFe12019 and a-Fe is formed after reduction of the precursor BaFel2019/a-Fe203 microfibers at 350 ℃ for 1 h. These nanocomposite microfibers are fabricated from a-Fe （16-22 nm in diameter） and BaFe12019 particles （36--42 nm in diameter） and basically exhibit a single-phase-like magnetization be- havior, with a high saturation magnetization and coercive force arising from the exchange--coupling interactions of soft a-Fe and hard BaFe12019. The microwave absorption characteristics in a 2-18 GHz frequency range of the nanocomposite BaFe12O19/a-Fe microfibers are mainly influenced by their mass ratio of a-Fe/BaFe12019 and specimen thickness. It is found that the nanocomposite BaFelzO19/a-Fe microfibers with a mass ratio of 1：6 and specimen thickness of 2.5 mm show an optimal reflection loss （RL） of -29.7 dB at 13.5 GHz and the bandwidth with RL exceeding -10 dB covers the whole Ku-band （12.4-18.0 GHz）. This enhancement of microwave absorption can be attributed to the heterostruc- ture of soft, nano, conducting a-Fe particles embedded in hard, nano, semiconducting barium ferrite, which improves the dipolar polarization, interfacial polarization, exchange--coupling interaction, and anisotropic energy in the nanocomposite BaFe12O19/a-Fe microfibers.

Two-dimensional materials-decorated microfiber devices for pulse generation and shaping in fiber lasers

Two-dimensional（2D） materials have been regarded as a promising nonlinear optical medium for fabricating versatile optical and optoelectronic devices. Among the various photonic applications, the employment of 2D materials as nonlinear optical devices such as saturable absorbers for ultrashort pulse generation and shaping in ultrafast lasers is one of the most striking aspects in recent years. In this paper, we review the recent progress of 2D materials based pulse generation and soliton shaping in ultrafast fiber lasers, and particularly in the context of 2D materials-decorated microfiber photonic devices. The fabrication of 2D materials-decorated microfiber photonic devices, high performance mode-locked pulse generation, and the nonlinear soliton dynamics based on pulse shaping method are discussed. Finally, the challenges and the perspective of the 2D materials-based photonic devices as well as their applications are also discussed.

Highly sensitive and miniature microfiber-based ultrasound sensor for photoacoustic tomography

A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interaction between optical signal and ultrasound wave,exhibiting a high sensitivity of 3.5 mV/kPa,which is approximately 10 times higher than the single-mode fiber sensor.Meanwhile,a phase feedback stabilization module is introduced into the coherent demodulation system for long-term stable measurement.In addition,a photoacoustic tomography experiment with the microfiber ultrasound sensor is implemented to verify the excellent performance on imaging,with the depth of 12 mm,the highest lateral resolution of 65μm and axial resolution of 250μm,respectively.The highly sensitive microfiber ultrasound sensor provides a competitive alternative for various applications,such as industrial non-destructive testing,biomedical ultrasound and photoacoustic imaging.

Double-layer microwave absorber of nanocrystalline strontium ferrite and iron microfibers

Microwave absorption properties of the nanocrystalline strontium ferrite （SrFe12O19） and iron （α-Fe） microfibers for single-layer and double-layer structures are investigated in a frequency range of 2 GHz 18 GHz. For the singlelayer absorbers, the nanocrystalline SrFe12O19 microfibers show some microwave absorptions at 6 GHz 18 GHz, with a minimum reflection loss （RL） value of -11.9 dB at 14.1 GHz for a specimen thickness of 3.0 mm, while for the nanocrystalline α-Fe microfibers, their absorptions largely take place at 15 GHz-18 GHz with the RL value exceeding -10 dB, with a minimum .RL value of about -24 dB at 17.5 GHz for a specimen thickness of 0.7 mm. For the doublelayer absorber with an absorbing layer of α-Fe microfibers with a thickness of 0.7 mm and matching layer of SrFe12O19 microfibers with a thickness of 1.3 ram, the minimum RL value is about -63 dB at 16.4 GHz and the absorption band width is about 6.7 GHz ranging from 11.3 GHz to 18 GHz with the RL value exceeding -10 dB which covers the whole Ku-band （12.4 GHz 18 GHz） and 27% of X-band （8.2 GHz 12.4 GHz）.

Wavelength and sensitivity tunable long period gratings fabricated in fluid-cladding microfibers

We report the fabrication of long period gratings in fluid-cladding microfibers by directly focusing a femtosecond laser beam on the microfibers surface to induce periodical modification a long one side of the microfibers.A long period grating is fabricated in a water-cladding microfiber with a diameter of~5μm,which demonstrates a resonant attenuation of 28.53 dB at wavelength of 1588.1 nm with 10 pitches.When water cladding is changed to be refractive index oil of n=1.33 and alcohol solution with concentration of 5%,the resonance wavelength shifts to 1575.1 nm with resonant attenuation of 24.91 dB and 1594.1 nm with resonant attenuation of 35.9 dB,respectively.The long period grating demonstrates different temperature sensitivities of-0.524 nm/℃,-0.767 nm/℃and-1.316 nm/℃for water,alcohol solution and refractive index oil cladding microfibers,respectively,which means the alterable liquid cladding allows the availability of tunable wavelength and sensitivity.The fluid-cladding protects the microfibers from external disturbance and contamination and allows more flexibility in controlling the transmission property and sensing characteristics of long period gratings,which can be used as fiber devices and sensors for chemical,biological,and environmental applications.

Improved Fibroblast Adhesion and Proliferation by Controlling Multi-level Structure of Polycaprolactone Microfiber

Improving wound healing efficiency is a key issue for high performance dressings.The surface topology of fibers in wound dressings plays an important role in regulating cell behaviors during the regeneration.Herein,a polycaprolactone(PCL)scaffold with a shish-kebab structure was prepared by electrospinning and solution-induced crystallization.L929 cells were used to investigate the behavior of fibroblasts on the multi-level microfiber.The results showed that the shish-kebab fiber-based scaffold enhanced the cell proliferation when compared with the normal fiber and the fiber with a porous structure.Protein absorption,cell adhesive force,and cell modulus also increased by the shish-kebab fiber.The shish-kebab fiber-based scaffold with improved fibroblast-regulation ability can be applied in rapid wound healing.

Numerical Calculation of Seawater Temperature Sensing Based on Polydimethylsiloxane-Coated Microfiber Knot Resonator

A seawater temperature sensing method based on polydimethylsiloxane-coated (PDMS-coated) microfiber knot resonator (MKR) is proposed, which has the advantages of high sensitivity and weak salinity dependence. The dependences of the temperature sensitivity on fiber diameter, coating thickness and probing wavelength are theoretically investigated and the range of coating thickness for weak salinity dependence is obtained. By optimizing the parameters of the seawater temperature sensing system, when the probing wavelength is 1550 nm, the fiber diameter is 1 μm, and the coating thickness is 5 μm, the sensitivity can reach to 0.197 nm/°C. Results shown here are beneficial to find the optimal parameters for the temperature sensors with high sensitivity and weak salinity dependence.

Adding microfiber glass to increase the magnetic alignment of bonded magnets

To investigate the effect of adding microfiber glass on the magnetic and mechanic properties of anisotropic Nd-Fe-B magnets, the Nd-Fe-B magnets with epoxy resin lubricant were prepared by calendering and magnetic alignment steps with heating. The effect of heating during magnetic alignment process on magnetic and mechanic properties of the prepared Nd-Fe-B magnets was investigated and optimized. As a result, heating unaligned flexible bonded magnets to 100 °C for 30 min during magnetic alignment resulted in the largest (BH)_(max), which increased to over 61.5% with DOA increasing and to over 38% compared with unaligned Nd-Fe-B magnets prepared by one step method.

Microwave absorption properties of a double-layer absorber based on nanocomposite BaFe_(12)O_(19)/α-Fe and nanocrystalline α-Fe microfibers

The nanocomposite BaFe12O19/α-Fe and nanocrystalline α-Fe microfibers with diameters of 1-5 μm, high aspect ratios and large specific areas are prepared by the citrate gel transformation and reduction process. The nanocomposite BaFe12O19/α-Fe microfibers show some exchange-coupling interactions largely arising from the magnetization hard （BaFe12019） and soft （a-Fe） nanoparticles. For the microwave absorptions, the double-layer structures consisting of the nanocomposite BaFe12O19/α-Fe and α-Fe microfibers each exhibit a wide band and strong absorption behavior. When the nanocomposite BaFel2O19/α-Fe microfibers are used as a matching layer of 2.3 mm in thickness and a-Fe microfibers as an absorbing layer of 1.2 mm in thickness, the optimal reflection loss （RL） achieves -47 dB at 15.6 GHz, the absorption bandwidth is about 12.7 GHz ranging from 5.3 to 18 GHz, exceeding -20 dB, which covers 72.5% C-band （4.2-8.2 GHz） and whole X-band （8.2-12.4 GHz） and Ku-band （12.4-18 GHz）. The enhanced absorption properties of these double-layer absorbers are mainly ascribed to the improvement in impedance matching ability and microwave multi-reflection largely resulting from the dipolar polarization, interfacial polarization, exchange-coupling interaction, and small size effect.

Effect of Ecotype Carrier for Disperse Dye on Dyeing of Polyester Microfiber

The effect of "Eco" carrier SML for disperse dye on dyeing of polyester microfiber was studied. With respect of the result of effects of SML on dyeing rate curve, dye build - up, migration of dyed polyester microfiber and K/S, color property, color fastness of dyed polyester microfiber fabrics, SML has a significant application perspective, deserving practical uses.

Numerical and experimental analysis of long period gratings in wavelength scale elliptical microfibers

We report the fabrication of long-period gratings （LPGs） in elliptical microfibers with femtosecond laser. Based on the numerical analysis of the modes and the mode coupling condition of elliptical microfibers, an LPG is fabricated with a very short pitch of 10 μm by periodically modifying the fiber surface, which demonstrates very strong polarization-dependent resonances, a very low temperature sensitivity of a few picometers in air, and high temperature sensitivity of -1.62 nm/℃ in refractive index oil.

Bond Durability of Carbon-Microfiber-Reinforced Alkali-Activated High-Temperature Cement Adhering to Carbon Steel

The study aims at evaluating the bond durability of a carbon microfiber (CMF)-reinforced alkali-activating calcium aluminate cement (CAC)/fly ash F (FAF) blend cementitious material adhering to carbon steel (CS) under stresses induced by a 350℃ heat-25℃ water cooling cycle. This cementitious material/CS joint sample was originally prepared in an autoclave at 300℃ under a pressure of 8.3 MPa. For comparison, two reference geothermal well cements, Class G modified with silica (G) and calciumaluminum phosphate (CaP), were employed as well reinforced with CMF. In the CAC/FAF blending cement systems, the CAC-derived cementitious reaction products preferentially adhered to CS surfaces, rather than that of FAF-related reaction products. CMF played a pivotal role in creating tough interfacial bond structure of cement layer adhering to CS. The bond toughness also was supported by the crystalline cementitious reaction products including sodalite, brownmillerite, and hedenbergite as major phases, and aragonite, boehmite, and garronite as minor ones. The brownmillerite as an interfacial reaction product between cement and CS promoted the chemical bonding of the cement to CS, while the other phases served in providing the attractive bonding of the cement to CS. The post-stress-test joint samples revealed the formation of additional brown-millerite, aragonite, and garronite, in particular brownmillerite as the major one. The combination of chemical bonding and self-advancing adherence behavior of the cement was essential for creating a better interfacial bond structure. A similar interfacial bond structure was observed with CaP. The crystalline phase composition of the autoclaved cement revealed apatite, zeolite, and ferrowyllieite as major reaction products, and aragonite and al-katoite as the minor ones. Ferrowyllieite was identified as cement/CS interfacial reaction product contributing to the chemical bond of cement, while the other phases aided in providing the attractive bond of cement. After a stress test, two phases, ferrowyllieite and aragonite, promoted the self-advancing adherence of cement to CS. However, the effectiveness of these phases in improving adherence performance of cement was less than that of CAC/FAF blend cement, reflecting the fact that the bond durability of CAC/FAF blend cement was far better than that of the CaP. In contrast, the autoclaved silica-modified G cement consisting of xonotlite, and 0.9 nm-to-bermorite and riversideite, with calcite as the crystalline reaction products, had no significant effect on improving the shear bond strength and the bond’s toughness. No interaction product with CS was found in the cement adhering to CS. After a stress test, the calcite phase acted only to promote the self-advancing adherence of cement, but its extent was minimal compared with that of the other cements, thereby resulting in poor bond durability.

Temperature and strain sensitivities of surface and hybrid acoustic wave Brillouin scattering in optical microfibers

Temperature and strain sensitivities of surface acoustic wave(SAW)and hybrid acoustic wave(HAW)Brillouin scat-tering(BS)in 1μm-1.3μm diameter optical microfibers are simulated.In contrast to stimulated Brillouin scattering(SBS)from bulk acoustic wave in standard optical fiber,SAW and HAW BS,due to SAWs and HAWs induced by the coupling of longitudinal and shear waves and propagating along the surface and core of microfiber respectively,facilitate innovative detection in optical microfibers sensing.The highest temperature and strain sensitivities of the hybrid acoustic modes(HAMs)are 1.082 MHz/℃and 0.0289 MHz/με,respectively,which is suitable for microfiber sensing applica-tion of high temperature and strain resolutions.Meanwhile,the temperature and strain sensitivities of the SAMs are less affected by fiber diameter changes,ranging from 0.05 MHz/℃/μm to 0.25 MHz/℃/μm and 1×10^(-4) MHz/με/μm to 5×10^(-4) MHz/με/μm,respectively.It can be found that that SAW BS for temperature and strain sensing would put less stress on manufacturing constraints for optical microfibers.Besides,the simultaneous sensing of temperature and strain can be realized by SAW and HAW BS,with temperature and strain errors as low as 0.30℃-0.34℃and 14.47με-16.25με.