Reduction Of Radius Research Articles

The Hydrophobic Surfactant Proteins Strongly Induce Lipid Curvature

The hydrophobic surfactant proteins, SP‐B and SP‐C, greatly accelerate adsorption by vesicles of the surfactant lipids to form a film that lowers the surface tension in the lungs. Pulmonary surfactant enters the interface by a process analogous to the fusion of two vesicles. Like fusion, several factors affect adsorption according to how they alter the curvature of lipid leaflets, and suggest that adsorption proceeds via a rate‐limiting structure with negative curvature, in which the hydrophilic face of the phospholipid leaflets is concave. The studies reported here tested whether the surfactant proteins might promote adsorption by inducing the lipids to adopt more negative curvature, closer to the configuration of the hypothetical intermediate. We used X‐ray diffraction to determine how the proteins in their physiological ratio affect the radius of cylindrical monolayers in the negatively curved, inverse hexagonal phase. With binary mixtures of dioleoyl phosphatidylethanolamine (DOPE) and dioleoyl phosphatidylcholine (DOPC), the proteins produced a dose‐related effect on curvature that depended on the phospholipid composition. With DOPE alone, the proteins produced no change. With increasing amounts of DOPC, the response to the proteins increased, reaching a maximum 50% reduction in cylindrical radius at 5% (w:w) protein. This change represented a doubling of curvature at the outer cylindrical surface. The change in spontaneous curvature, defined at approximately the level of the glycerol group, would be greater. Our findings show that the surfactant proteins can promote negative curvature, and support the possibility that they facilitate adsorption by that mechanism.

Tracking Anatomical Variation of the Bifurcation of the Radial Nerve: Clinical Implication for Physicians

Regional nerve blocks of the upper limb are usually performed in the brachial plexus, specifically in the supra- or infra-clavicular or axillary nerve regions, in cases where minor surgical procedures are required in the distal portion of the extremity. These approaches may not be optimal due to the close proximity of major vascular structures to the needle entry site. This quantitative study measured the site of the radial nerve bifurcation using calipers and ultrasound (US) to determine whether minor surgical procedures (i.e., wound exploration, laceration repair and distal radius reduction) could rely on nerve blocks within a single nerve distribution, in a defined region of the cubital fossa. A metal cylinder was aligned along the medial and lateral epicondyles of 59 donor body arms. A digital caliper, perpendicular to the cylinder, allowed for measurement above (+) or below (-) the epicondylar line (0mm). The average bifurcation occurred at -13.84mm, with 85% of bifurcations arising in the forearm below 0mm. US digital data from a cross-sectional sample of live patients were included in our analysis. US guided needle nerve blocks are presently used by physicians for cases involving injury distal to the elbow. Our results indicate that it is possible to establish “safe zone” parameters in regional nerve blocks to maximize functional recovery while minimizing collateral vascular damage.

Spring-in of curved CFRP/foam-core sandwich structures

This paper reports on a comprehensive study on process-induced distortions (PID) of curved CFRP/foam-core sandwich panels. The study’s aim is to validate the prediction quality of two existing analytical models and a novel straightforward simulation technique, which utilizes measured spring-in distortions of representative monolithic samples as input. Sandwich specimens with a radius of approximately 350mm are manufactured with three different core thicknesses and two different core run-out geometries.The manufactured parts show a significant radius reduction which declines for increasing core thickness which is satisfactorily predicted by both, the analytical models and the simulation. The effect of the run-out shape turned out to be of inferior relevance for the investigated specimen configurations. However, it is found to be essential to use plane-stress assumptions and to capture the stiffness ratio between the skins and the core. Therefore, an extension of the Fernlund model is proposed whose predictions match excellently with the measured distortion of the specimens. Given the simplicity of the simulation approach in combination with the limited number of inputs makes it a tool of great value, particularly early on in the design cycle.

Influence of notch radius on the fracture load of piezoelectric ceramics

The influence of root radius of notch applied fracture load on piezoelectric ceramics under various conditions of electric fields was studied using the three-point bending test. And the linear finite element analysis associated with energy density of crack as a feasible parameter of fracture was performed with piezoelectricity. It was found that the fracture load is decreased according to reduction of the curvature radius of notch but the finite element analysis showed reverse result, the fracture load in case of the crack is increased. The energy density of crack as the governing fracture parameter was finally introduced and discussed.

Structures and properties of polyimide fibers containing ether units

Copolyimide (co-PI) fibers containing 4,4′-oxydiphthalic anhydride (ODPA) moiety into the 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)/p-phenylenediamine backbone were prepared via a two-step wet-spinning method. The processability and mechanical properties were improved significantly after the incorporation of ODPA, and the fibers exhibited an optimum tensile strength of 10.94 cN dtex−1 and modulus of 470.52 cN dtex−1 with elongation of 2.75 % at a BPDA/ODPA molar ratio of 7/3. Two-dimensional wide angle X-ray diffraction indicated that highly oriented structures and ordered molecular packing regions were formed in the fibers. Two-dimensional small angle X-ray scattering revealed that the incorporation of ODPA resulted in the reduction in radius, length, misorientation, and internal surface roughness of the microvoids in the fibers simultaneously, which was supposed to be mainly dominated for the drastically improved mechanical properties of PI fibers. Moreover, the co-PI fibers exhibited excellent thermal and thermal-oxidative stability, and the 5 % weight loss temperature was above 572 and 535 °C under nitrogen and air, respectively.

Spherical bubble dynamics in a bubbly medium using an Euler–Lagrange model

For applications involving large bubble volume changes such as in cavitating flows and in bubbly two-phase flows involving shock and pressure wave propagation, the dynamics, relative motion, deformation, and interaction of bubbles with the surrounding medium play crucial roles and require accurate modeling. We present in this paper a fundamental study of the dynamic oscillations of a “primary” bubble in a bubbly mixture using a two-way coupled Euler–Lagrange model. It addresses a simplified spherical configuration while using the full three-dimensional code. A main objective of the study is to investigate how the dynamics of a “primary” bubble is affected by the presence of a surrounding bubbly medium and how it differs from its behavior in a pure liquid. This helps elucidate the physics at play for this relatively simple configuration. The model simulates the mixture as a continuum and solves the corresponding Navier Stokes equations with grids moving with the interface of the primary bubble wall. The surrounding microbubbles are tracked in a Lagrangian fashion accounting for their volume evolution. The two-way coupling between the bubbly medium and the primary bubble dynamics is realized through the local density of the mixture obtained from the tracking of the microbubbles and the determination of their volumes and spatial distribution.The simulations clearly indicate that the surrounding microbubbles absorb energy emitted from the primary bubble during its oscillations. This results in a reduction of the maximum radius and the period of oscillations of the primary bubble as compared to the dynamics in the pure liquid. Also, accounting for the dynamics of the field bubbles brings out the presence in the two-phase medium of a phase shift between density and pressure distributions. Such a shift is not captured by two-phase homogeneous medium models. These effects increase with increase in the mixture void fraction and in the initial bubble sizes in the mixture. The numerical observations are found to be in good qualitative agreements with previously published experimental data (Jayaprakash et al., 2011) investigating spark generated bubble dynamics in a bubbly medium.

On the diameter dependence of metal-nanowire Schottky barrier height

Bardeen's model for the non-ideal metal-semiconductor interface was applied to metal-wrapped cylindrical nanowire systems of 30–400 nm in diameter; a significant effect of the nanowire diameter on the non-ideal Schottky barrier height was found. The calculations were performed by solving Poisson's equation in the nanowire, self-consistently with the constraints set by the non-ideal interface conditions; in these calculations, the barrier height is obtained from the solution, and it is not a boundary condition for Poisson's equation. The main finding is that thin nanowires are expected to have O(10−100) meV higher Schottky barriers compared to their thicker counterparts; an effect 3–4 times stronger than the diameter dependence of image-force barrier lowering in similar systems. What lies behind this effect is the electrostatic properties of metal-wrapped nanowires; in particular, since depletion charge is reduced with nanowire radius, the potential drop on the interfacial layer is reduced—leading to the increase of the barrier height with nanowire radius reduction.

Geometry and respiratory-induced deformation of abdominal branch vessels and stents after complex endovascular aneurysm repair

This study quantified the geometry and respiration-induced deformation of abdominal branch vessels and stents after fenestrated (F-) and snorkel (Sn-) endovascular aneurysm repair (EVAR). Twenty patients (80% male; mean age, 75.2 ± 7.4 years; mean aneurysm diameter, 6.2 ± 1.8 cm) underwent computed tomography angiography during inspiratory and expiratory breath hold protocols after F-EVAR (n = 11) or Sn-EVAR (n = 9). Centerlines for the aorta and visceral vessels were extracted from three-dimensional models. Branch angles were computed relative to the orthogonal plane at the branch ostia, and end-stent angles of the left renal artery (LRA) and right renal artery (RRA) were computed relative to the distal stent orientation. The radius of peak curvature was defined by the circumscribed circle at the highest curvature. Sn-renal branches were more downward-angled than F-renal branches (P < .04). At the distal ends of the RRA stents, Sn-RRAs were angled greater than F-RRAs (P < .03) and had a smaller radius of peak curvature (P < .03). With expiration, the end-stent angle of Sn-LRAs increased by 4° ± 4° (P < .02) and exhibited a significant reduction of radius of curvature (P < .04). The unstented celiac arteries were more downward-angled (P < .02, inspiration), with a smaller radius of curvature (P < .00001), than the unstented superior mesenteric arteries. With expiration, the celiac arteries angled upwards by 9° ± 9° (P < .0005), which was greater than the superior mesenteric arteries (P < .03). At a median postoperative follow-up of 12.6 months (range, 1.0-37.1 months), branch vessel patency was 100%, serum creatinine levels remained stable, and one reintervention was required for a type III endoleak at the main body-LRA stent interface. Sn-renals were angled more inferiorly at the branch and more angulated at the stent end than F-renals due to stent placement strategies. Sn-LRAs exhibited a significant change in end-stent angle and curvature during respiration, a finding that may compromise long-term durability for parallel stent graft configurations. Further investigation is warranted to better optimize anatomic, patient, and branch vessel stent selection between fenestrated and snorkel strategies and their relationship to long-term patency.

曲げ加工された冷間圧延鋼板の面外曲げ疲労強度

Fatigue tests were conducted on 90°V-shape bending-worked cold rolled steel sheet specimens under fully-reversed out-of-plane bending to investigate the fatigue strength of bending-worked plates. The tests were also performed on low-temperature annealed specimens with no work-hardened layer formed by the bending-work. For annealed specimens, the fatigue strength decreased with reduction in radius of curvature of bending. The fatigue life can be estimated with sufficient accuracy taking account of the influence of elastic-plastic stress concentration at critical location. For bending-worked specimens without annealing, the fatigue strength was relatively higher than those of annealed bent specimens in relation to the existence of work-hardened layer. The increase of fatigue strength due to work-hardening was estimated based on the difference in S-N diagrams of both specimens. Consequently, the fatigue life of bending-worked specimens without annealing can be evaluated taking the effects of stress concentration and work-hardening into consideration.

Outcomes of long-arm casting versus double-sugar-tong splinting of acute pediatric distal forearm fractures.

The traditional treatment after closed reduction of distal radius (DR) and distal both bone (DBB) forearm fractures has been application of a long-arm cast (LAC) or a short-arm cast (SAC). Splinting is another option that avoids the potential complications associated with casting. The purpose of this study is to evaluate the maintenance of reduction of DR or DBB fractures placed in a double-sugar-tong splint (DSTS) compared with a LAC in a pediatric population. This is an IRB-approved, prospective, randomized trial. Patients aged 4 to 12 years with DR or DBB fractures treated at a single institution between 2010 and 2012 were enrolled. After reduction, fractures were placed into either a LAC or a DSTS. Radiographs were reviewed at initial injury, postreduction, and at set intervals for angulation, displacement, and apposition, as well as cast index and 3-point index. The DSTS was overwrapped into a cast after week 1. The immobilization device was changed to a SAC at week 4 or 6. Total duration of immobilization was 6 to 8 weeks. Seventy-one patients were enrolled with 37 in the LAC and 34 in the DSTS. Average age was 8.73 years (range, 4 to 12) with 43 being males. There were 28 isolated DR and 43 DBB fractures. There were no week-to-week differences between the 2 groups in regards to sagittal alignment, coronal alignment, apposition, or displacement. Sagittal alignment at immediate postreduction and week 2 showed that the DSTS was slightly better (average 2.0 vs. 5.0 degrees, respectively, P=0.04). For the entire treatment period there was an increased risk of loss of reduction of ≥10 degrees in the LAC group versus the DSTS group (7 patients vs. 2 patients, respectively, P=0.0001), and of meeting the criteria for remanipulation (10 patients vs. 5 patients, respectively, P=0.01). At cast removal, there was no difference between groups. Although there were significant differences between the 2 groups with regards to risk of reduction loss, the DSTS and LAC were comparable in maintenance of reduction at the time of cast removal. Both the DSTS and LAC are appropriate immobilization devices for these pediatric fractures. Level II-prospective, comparative study.

Arthroscopy for Galeazzi fractures, a way to demonstrate TFCC damage in extra-articular radius fracture: A series of 7 cases

Galeazzi fracture is a trauma associating diaphysal radius fracture and dislocation or subluxation of the distal radio-ulnar joint (DRUJ). Despite an anatomic reduction of the radius, DRUJ impairment, especially injury of triangular fibrocartilage complex (TFCC) may lead to partial instability with secondary pain and stiffness. This prospective case series proposes to perform wrist arthroscopy for Galeazzi fractures in order to diagnose ligamentous injuries and to enable their reparations. Over a period of 18 months, 7 recent Galeazzi closed fractures were operated on with wrist arthroscopy. We used a locking compression plate, a 1.9 mm arthroscope with 3 radio-carpal portals: 3-4, 4-5 and 6U. A dorsal forearm splint was kept for 3 weeks followed by an active/passive physiotherapy. Physical examination and X-ray were performed after 3, 6 and 12 weeks. Analysis criteria were: – perioperative: ligament impairment, duration of surgery; – postoperative: pain, wrist motion (flexion/extension; prono/suppination), grasp strength, time off work and sports, X-ray analysis (reduction, consolidation, secondary displacement). All patients were reviewed 3 times. The triangular ligament was injured in all cases, 3 cases in the radial part, 3 cases in the ulnar part and one both side. All ulnar injuries were repaired systematically. The radial TFCC injuries were only repaired when DRUJ instability persisted despite good reduction of the radius. After osteosynthesis of the radius, DRUJ remained instable in 3 cases, one ulnar lesion, one radial and one both side. The reparation of the triangular ligament improved stability of the DRUJ in 2 cases, one case remained instable despite TFCC reparation. About strength and mobility: – after 3 weeks: F/E: 50/60°, P/S 45°/45°, grasp 20%; – after 6 weeks: F/E: 80/80°, P/S 70°/60°, grasp 45%; – after 12 weeks: F/E: 85/80°, P/S 80°/75°, grasp 80%. We noticed 7 anatomic radius reductions and no secondary displacement. A dorsal DRUJ subluxation was noticed despite the ulnar TFCC repair; none nonunion was reported. Time off work was 7 weeks (4–10). Functional mobility was regained after 6 weeks, accompanied by good strength. TFCC reparation participate in DRUJ stabilization but was not always sufficient to fully stabilize the DRUJ. A next study with DRUJ MRI and prono-supination strength measurement should participate to demonstrate further benefits of TFCC reparation in Galeazzi fractures. A lesion of the TFCC was noticed in all cases suggesting that TFCC lesion could occur in some other extra-articular distal radius fractures.

Treatment of distal radius fractures with wrist arthroscope-assisted closed reduction and external fixation

Objective To introduce the technique and treatment outcomes of arthroscope-assisted closed reduction and external fixation of distal radius fractures.Methods Twenty-five cases of distal radius fractures were treated arthroscopically with closed reduction and external fixation between November 2011 and October 2013.Sarmiento score modified by Stewart was used for assessment of fracture reduction and healing.Cooney score was applied to evaluate postoperative wrist function.Results All the patients were follow-up for an average of 10.6 months.All the fractures healed well.Postoperative X-ray showed 11.9° of palmar tilt and 20.1° of ulnar inclination on average.According to the modified Sarmiento score,the surgical results were rated as excellent in 22 cases,good in 2 cases and fair in 1 case.According to Cooney wrist score,the function of the wrist was rated as excellent in 20 cases,good in 4 cases,and fair in 1 case.Conclusion Arthroscope-assisted closed reduction and external fixation is a less invasive and more effective treatment for distal radius fractures. Key words: Arthroscopy; External fixators; Distal radius fracture; Closed reduction; Minimally invasive

Radius of Curvature Effects on Throat Thermochemical Erosion in Solid Rocket Motors

Ablative materials are commonly used to protect the nozzle housing and to provide the internal contour to expand the exhaust gases in solid rocket motors. However, thermochemical erosion of nozzle thermal protection material results in a throat area enlargement that reduces the chamber pressure and the thrust as well as the thrust coefficient. The resulting specific impulse loss can be significant, especially for small-scale systems. To understand if throat erosion can be limited by suitable shaping of the nozzle contour, the present work addresses the study of the effect of the throat radius of curvature on the thermochemical erosion behavior of graphite nozzles for a typical metallized solid propellant. The adopted approach relies on a validated full Navier–Stokes flow solver coupled with a thermochemical ablation model based on finite-rate chemistry. A shape change analysis is also conducted to determine how different nozzle contours are modified during the advancement of the erosion process. Results allow the quantification of the overall performance increase that can be obtained by a suitable reduction of the throat radius of curvature.

Aging of fullerene C60 nanoparticle suspensions in the presence of microbes

Despite the growing use of carbon nanomaterials in commercial applications, very little is known about the fate of these nanomaterials once they are released into the environment. The carbon–carbon bonding of spherical sp2 hybridized fullerene (C60) forms a strong and resilient material that resists biodegradation. Moreover, C60 is widely reported to be bactericidal. Here however, we observe the changing properties of fullerene nanoparticle aggregates aged in the presence of microbes. C60 aggregates were observed to decrease in size with aging, while hydroxylation and photosensitized reactivity measured by the production of reactive oxygen species (ROS) increased, suggesting that chemically and/or biologically-mediated activity is capable of partially transforming fullerene structure and reactivity in the environment. However, stable-isotope-labeling C60 aggregates incubated with microbial cultures from aged suspensions for 203 days did not produce significant labeled carbon dioxide, despite significant reduction in aggregate radius for biological samples. These results suggest that either the rate of biodegradation of these particles is too slow to quantify or that the biologically-enhanced transformation of these particles does not occur through microbial biodegradation to carbon dioxide.

Design of pseudo-symmetric high bit rate, bend insensitive optical fiber applicable for high speed FTTH

In this paper, with sophisticated modification on modal-field distribution and introducing new design procedure, the single-mode fiber with ultra-low bending-loss and pseudo-symmetric high bit-rate of uplink and downlink, appropriate for fiber-to-the-home (FTTH) operation is presented. The bending-loss reduction and dispersion management are done by the means of Genetic Algorithm. The remarkable feature of this methodology is designing a bend-insensitive fiber without reduction of core radius and MFD. Simulation results show bending loss of 1.27×10−2dB/turn at 1.55μm for 5mm curvature radius. The MFD and Aeff are 9.03µm and 59.11µm2. Moreover, the upstream and downstream bit-rates are approximately 2.38Gbit/s-km and 3.05Gbit/s-km.

Recess swaging method for manufacturing the internal helical splines

With the advantages of minimized stress concentration and allowing a combination of rotation and axial motion, internal helical splines have been widely used in automotive and aeronautic industries. However, this type of splines can only be manufactured using machining or extrusion method. This paper studied the recess swaging method, a net-shape forming process, for manufacturing the internal helical splines. In order to investigate the deformation tendency of workpiece along the thickness direction, Finite Element (FE) simulations and experiments were firstly performed on the recess swaging of tube without mandrel. Results show that the stress state in the forging zone is triaxial compressive except for the tensile axial stress at the inner surface of the tube. Moreover, during the recess swaging process material mainly flows along the axial and thickness direction, but the axial flow dominates. With increasing the reduction in outer radius and the wall thickness, metal flow along the axial direction increases but along the thickness direction decreases. Furthermore, based on the fundamental research on recess swaging experiments and FE simulations on the recess swaging method for manufacturing the internal helical splines were conducted. After the recess swaging, the hardness at the bottom of the tooth improved approximately 56.9%, while that at other zones increased 41%. The strength and the wear resistance of tooth were also improved. In summary, the recess swaging process provides an effective method for manufacturing the internal helical splines.

A computational and experimental study of coflow laminar methane/air diffusion flames: Effects of fuel dilution, inlet velocity, and gravity

The influences of fuel dilution, inlet velocity, and gravity on the shape and structure of laminar coflow CH4–air diffusion flames were investigated computationally and experimentally. A series of nitrogen-diluted flames measured in the Structure and Liftoff in Combustion Experiment (SLICE) on board the International Space Station was assessed numerically under microgravity (μg) and normal gravity (1g) conditions with CH4 mole fraction ranging from 0.4 to 1.0 and average inlet velocity ranging from 23 to 90cm/s. Computationally, the MC-Smooth vorticity–velocity formulation was employed to describe the reactive gaseous mixture, and soot evolution was modeled by sectional aerosol equations. The governing equations and boundary conditions were discretized on a two-dimensional computational domain by finite differences, and the resulting set of fully coupled, strongly nonlinear equations was solved simultaneously at all points using a damped, modified Newton’s method. Experimentally, flame shape and soot temperature were determined by flame emission images recorded by a digital color camera. Very good agreement between computation and measurement was obtained, and the conclusions were as follows. (1) Buoyant and nonbuoyant luminous flame lengths are proportional to the mass flow rate of the fuel mixture; computed and measured nonbuoyant flames are noticeably longer than their 1g counterparts; the effect of fuel dilution on flame shape (i.e., flame length and flame radius) is negligible when the flame shape is normalized by the methane flow rate. (2) Buoyancy-induced reduction of the flame radius through radially inward convection near the flame front is demonstrated. (3) Buoyant and nonbuoyant flame structure is mainly controlled by the fuel mass flow rate, and the effects from fuel dilution and inlet velocity are secondary.

Genesis of Hurricane Julia (2010) within an African Easterly Wave: Developing and Nondeveloping Members from WRF–LETKF Ensemble Forecasts

Abstract In this study, the predictability of and parametric differences in the genesis of Hurricane Julia (2010) are investigated using 20 mesoscale ensemble forecasts with the finest resolution of 1 km. Results show that the genesis of Julia is highly predictable, with all but two members undergoing genesis. Despite the high predictability, substantial parametric differences exist between the stronger and weaker members. Notably, the strongest-developing member exhibits large upper-tropospheric warming within a storm-scale outflow during genesis. In contrast, the nondeveloping member has weak and more localized warming due to inhibited convective development and a lack of a storm-scale outflow. A reduction in the Rossby radius of deformation in the strongest member aids in the accumulation of the warmth, while little contraction takes place in the nondeveloping member. The warming in the upper troposphere is responsible for the development of meso-α-scale surface pressure falls and a meso-β surface low in the strongest-developing member. Such features fail to form in the nondeveloping member as weak upper-tropospheric warming is unable to induce meaningful surface pressure falls. Cloud ice content is nearly doubled in the strongest member as compared to its nondeveloping counterparts, suggesting the importance of depositional heating of the upper troposphere. It is found that the stronger member undergoes genesis faster due to the lack of convective inhibition near the African easterly wave (AEW) pouch center prior to genesis. This allows for the faster development of a mesoscale convective system and storm-scale outflow, given the already favorable larger-scale conditions.

Numerical study of the effect of anthropogenic aerosols on spring persistent rain over Eastern China

The effect of anthropogenic aerosols on the spring persistent rain (SPR) over eastern China is investigated by using a high-resolution Community Atmosphere Model version 5.1 (CAM5.1). The results show that the SPR starts later due to anthropogenic aerosols, with a shortened duration and reduced rainfall amount. A reduction in air temperature over the low latitudes in East Asia is linked to anthropogenic aerosols; so is a weakened southwesterly on the north side of the subtropical high. Meanwhile, air temperature increases significantly over the high latitudes. This north-south asymmetrical thermal effect acts to reduce the meridional temperature gradient, weakening the upper-level westerly jet over East Asia and the vertical motion over southeastern China. As a result, the SPR is reduced and has a much shorter duration. The indirect effect of anthropogenic aerosols also plays an important role in changing the SPR. Cloud droplet number concentration increases due to anthropogenic aerosols acting as cloud condensation nuclei, leading to a reduction in cloud effective radius over eastern China and a reduced precipitation efficiency there.

Theoretical investigation on the temperature characteristics of liquid-cladding micro/nanofiber Bragg grating

Based on the functions of the effective refractive index of fundamental mode in step-index fiber, a theoretical mode about the Bragg wavelength shift of micro/nanofiber Bragg grating (MNFBG) is presented. The numerical simulation results demonstrate, for a MNFBG with given radius, the Bragg wavelength shifts to short wavelength as ambient temperature increases, and the reason results from the effective index decreasing with the increase of ambient temperature. Moreover, with the reduction of fiber-core radius, as well as the increase of ambient index and its thermo-optic coefficient, the temperature sensitivity, linearity and linear response range of the temperature-dependent Bragg wavelength shift are improved obviously. Especially for a MNFBG with fiber radius smaller than 0.5 μm, the linearity of Bragg wavelength shifting with temperature will be close to the theoretical limit, and the temperature sensitivity is proportional to the thermo-optic coefficient of the ambient liquid. Compared with the temperature properties of conventional fiber Bragg grating (FBG), all the results will provide much theoretical guides for FBG applied in fiber sensing and communication.