Fiber Spacing Research Articles

Characterization of muscle development and gene expression in early embryos of chicken, quail, and their hybrids.

Myogenesis is a complex, regulated process that involves myoblast proliferation, migration, adhesion, and fusion into myotubes. To investigate early development of embryonic muscles and the expression of regulatory genes during myogenesis in chicken, quail and their hybrids, meat-breeding cocks and egg-breeding cocks were selected as male parents, quails were used as female parents. Their offspring were meat and egg hybrids via Artificial insemination. We measured expression of MUSTN1, IGF-1, and PDK4 using qRT-PCR. We examined muscle fiber diameter using scanning electron microscopy. The results showed that muscle development was two days slower in chicken, egg hybrid, and meat hybrid than in quail. Muscle fiber spacing was the largest in chicken, followed by meat hybrid, egg hybrid, and quail. A similar trend was obtained for muscle fiber diameter. Additionally, muscle fiber diameter increased with embryogenesis. The sarcomere was present on day 17 of incubation in quail, but not in the other species. MUSTN1 could up-regulated IGF-1 by activating PI3K/Akt. IGF-1 expression was consistent with myoblast proliferation and myotube fusion. PDK4 was expressed from E7 to E17. The first peak was reached on E10, egg hybrid and meat hybrid reached their peak at E15. PDK4 is involved in the early proliferation and differentiation of muscle, thereby affecting muscle growth and development. Our findings demonstrated that MUSTN1, IGF-1 and PDK4 genes are expressed to varying levels in breast muscle of chicken, quail, egg hybrid and meat hybrid during the embryonic period. Interestingly, with increasing embryonic age, muscle development was approximately 48h faster in quail than in other species. We speculated that MUSTN1, IGF-1 and PDK4 genes may be the main candidate genes that cause differences in poultry muscle traits, but the molecular regulation mechanisms need to be further studied. Our findings shed some light on the avian embryo muscle formation and molecular breeding of poultry muscle traits, which provide theoretical basis for poultry breeding.

Some global, analytical, and topological properties of regular black holes

In this work we study regular black holes from a global perspective looking for evading some of the well-known singularity theorems by using their "reverses". Then, model geometries for the slices of typical spherically symmetric, (locally) static four dimensional regular black hole solutions are described from both an analytical and a topological point of view. While the finiteness of both the scalar and Kretchmann curvature of the slices around the regular center determines the geometry of the core, the positive answer to the Poincar\'e conjecture assures that, under two assumptions, its topology is that of a three-sphere. However, in general, the cores are shown to be $S^3$, $H^3$, $\mathbb{R}\times S^1$ or $S^1\times S^2$, depending whether a de Sitter, anti de Sitter, Nariai or Bertotti-Robinson geometries are employed to describe the slices at the regular center. Then, a description of the aforementioned slices in terms of Seifert fibre spaces is given in order to show that the Euler characteristic of the bundle can be used to track the transition between the core of the regular black hole and the rest of the slices in most of the cases considered in the literature. After Geroch and Tipler's theorems are employed to study the consequences of topology change on regular black hole spacetimes, we show that Borde and Vilenkin's singularity theorem is used to restrict their possible types. We end by noting that Nariai cores can be safely used to construct regular black holes without topology changes.

Geometry of Twisted Kähler–Einstein Metrics and Collapsing

We prove that the twisted Kahler-Einstein metrics that arise on the base of certain holomorphic fiber space with Calabi-Yau fibers have conical-type singularities along the discriminant locus. These fiber spaces arise naturally when studying the collapsing of Ricci-flat Kahler metrics on Calabi-Yau manifolds, and of the Kahler-Ricci flow on compact Kahler manifolds with semiample canonical bundle and intermediate Kodaira dimension. Our results allow us to understand their collapsed Gromov-Hausdorff limits when the base is smooth and the discriminant has simple normal crossings.

High selectivity of CO2 conversion to formate by porous copper hollow fiber: Microstructure and pressure effects

Electrochemical reduction of CO2 by Cu hollow fibers to CO with high selectivity has previously been reported but selective conversion of CO2 to formic acid at high current densities, although highly desirable, is still challenging. Herein, a Cu hollow fiber with an interconnected pore structure is fabricated via a facile method and used as a stand-alone cathode for highly efficient electrochemical reduction of CO2 to formate. We obtain a high selectivity for CO2 reduction to formate with a maximum FE of 77.1% at a high current density of 34.7 mA cm−2, one of the highest FE on Cu-based materials. Our results suggest that delivering the CO2 gas into the inner space of the hollow fiber leads to a higher CO2 partial pressure in the pores due to the pressure drop across the wall of the Cu hollow fiber. As both the CO2 and H+ ions (from the electrolyte) compete for adsorption on the Cu hollow fiber active sites, the higher CO2 partial pressure makes CO2 adsorption more favorable, thereby reducing the concentration of the H+ on the active sites. This effectively suppresses the major competing reaction, hydrogen evolution reaction (HER), from 46.9% Faradaic efficiency (FE) to 15.0%. Furthermore, our studies reveals the impotency of the co-existence of Cu(100) and Cu(110) active site facets towards excellent selectivity of formate formation under high CO2 partial pressure. Additionally, the designed catalyst also exhibits out-standing long-term stability at high current density, demonstrating potential for large-scale practical applications.

Protective mechanism of tea polyphenols against muscle quality deterioration of shrimp (Penaeus vannamei) induced by aflatoxin B1

Tea polyphenols (TP), as common antioxidants, have been widely used to mitigate for the protection and preservation of aquatic animals, but the protective effect of TP against the deterioration of shrimp muscle quality induced by aflatoxin B1 (AFB1) has not been reported. This study was designed to analyse the root cause of AFB1 induced declines in shrimp muscle quality and the protective mechanisms of TP at the molecular level. Shrimp were exposed to AFB1 and TP for 20 d following a dose-escalating trial, and changes to the muscle histopathology, basic nutrient composition, and protein composition were determined. Non-labelled quantitative proteomics was used to screen and identify differential marker proteins associated with AFB1 and TP. After 20 d of AFB1 exposure, the water content, crude protein content and crude fat content of the shrimp muscle decreased to 68.66%, 18.27% and 1.01%, respectively, while the ash content was positively correlated with AFB1 dose (R2 = 0.955). AFB1 caused damage to the shrimp muscle microstructure in a dose-dependent manner, such as significant enlargement of muscle fibre spaces, rupture of the sarcomere, inflammation and so on. AFB1 induced changes in muscle protein composition, resulting in a decrease in the content of myofibrillar, sarcoplasmic and stroma proteins, while the alkali-soluble protein content increased significantly. TP can effectively protect against the damage to shrimp muscle caused by AFB1 by inhibiting the expansion of muscle fibre spaces and inflammation. TP (0.04–0.16% feed) also had a significant protective effect against the decrease of muscle nutrients and changes in protein composition of shrimp caused by exposure to AFB1 (1.2–2.7 mg/kg feed) in the early and middle period (4–12 d), but the protective effect was weak or not noticeable in the late period (16–20 d). Eleven proteins were identified and screened as biomarker proteins of AFB1 induced quality decline and TP protection, which were involved in energy metabolism (fructose 1,6-bisphosphatase; transaldolase; fructose-bisphosphate aldolase; arginine kinase), redox reaction (hydroxyphenylpyruvate reductase; prostaglandin reductase 1; protein arginine N-methyltransferase 8), anti-inflammatory responses (5′-nucleotidase; actin-depolymerizing factor) and protein translation/folding (eukaryotic translation initiation factor 3; peptidyl-prolyl cis-trans isomerase). This study provides a better understanding of AFB1 induced damage to shrimp quality and technical guidance for the use of TP to prevent the damage during the culture and processing of Penaeus vannamei.

Effect of the muscle nanostructure changes during post-mortem aging on tenderness of different beef breeds.

ObjectiveTenderness is a very complex feature, and the process of its formation is very complicated and not fully understood. Its diversification is one of the most important problems of beef production, as a result beef aging is widely used to improve tenderness as it is believed to provide a homogeneous product to consumers. While few studies have evaluated the muscle structure properties in relation to tenderness from early post-mortem, there little to no information available on how the muscle nanostructure of beef carcasses changes during post-mortem ageing to determine the appropriate aging time for acceptable tenderness.MethodsMuscle nanostructure (myofibril diameter [MYD], myofibril spacing [MYS], muscle fibre diameter [MFD], muscle fibre spacing [MFS], and sarcomere length [SL]), meat tenderness and cooking loss [CL]) were measured on 20 A2 longissimus muscles of Bonsmara, Beefmaster, Hereford, and Simbra at 45mins, 1, 3, and 7 days post-slaughter. Muscle nanostructure was measured using a scanning electron microscope, while tenderness was measured using Warner Bratzler shear force.ResultsAt 45 minutes post-slaughter, breed affected MYD and MYS only, while at 24hrs it also affected MFD and MFS. On day 3 breed effected MFS and SL, while on day 7 breed effected tenderness only. As the muscles matured, both MYD and MYS decreased while CL increased, and the muscles became tender. There was no uniformity on muscle texture features (surface structure, fibre separation, muscle contraction, and relaxation) throughout the ageing period.ConclusionMeat tenderness can be directly linked to breed related myofibril structure changes during aging in particular the MYD, spacing between myofibrils and their interaction; while the MFD, spacing between muscle fibres, SL, and CL explain the non-uniformity in beef tenderness.

Teichmüller spaces and coefficient problems for univalent holomorphic functions

We show that the features of Teichmuller spaces give rise to a completely new powerful tool for solving the classical coefficient problems in geometric function theory. Here we concern the univalent functions. Using the Bers isomorphism theorem for Teichmuller spaces of punctured Riemann surfaces and some of their other complex geometric features, we prove a general theorem on maximization of homogeneous polynomial (in fact, more general holomorphic) coefficient functionals $$J(f) = J(a_{m_1}, a_{m_2},\dots , a_{m_n}) $$ on some classes of univalent functions in the unit disk naturally connected with the canonical class S. The given functional J is lifted to the Teichmuller space $$\mathbf{T}_1$$ of the punctured disk $$\mathbb {D}_{*} = \{0< |z| < 1\}$$ which is biholomorphically equivalent to the Bers fiber space over the universal Teichmuller space. This generates a positive subharmonic function on the disk $$\{|t| < 4\}$$ with $$\sup _{|t|<4} u(t) = \max _{{\mathbf {T}}_1} |J|$$ attaining this maximal value only on the boundary circle, which correspond to rotations of the Koebe function. This theorem implies new sharp distortion estimates for univalent functions giving explicitly the extremal functions, and creates a new bridge between Teichmuller space theory and geometric complex analysis. In particular, it provides an alternate and direct proof of the Bieberbach conjecture.

F-theory and heterotic duality, Weierstrass models from Wilson lines

We present how to construct elliptically fibered K3 surfaces via Weierstrass models which can be parametrized in terms of Wilson lines in the dual heterotic string theory. We work with a subset of reflexive polyhedras that admit two fibers whose moduli spaces contain the ones of the E_{8}times E_{8} or frac{Spin(32)}{{mathbb {Z}}_{2}} heterotic theory compactified on a two torus without Wilson lines. One can then interpret the additional moduli as a particular Wilson line content in the heterotic strings. A convenient way to find such polytopes is to use graphs of polytopes where links are related to inclusion relations of moduli spaces of different fibers. We are then able to map monomials in the defining equations of particular K3 surfaces to Wilson line moduli in the dual theories. Graphs were constructed developing three different programs which give the gauge group for a generic point in the moduli space, the Weierstrass model as well as basic enhancements of the gauge group obtained by sending coefficients of the hypersurface equation defining the K3 surface to zero.

Subadditivity of generalized Kodaira dimensions and extension theorems

In this paper, we introduce the notion of generalized Kodaira dimension with multiplier ideal sheaves, and prove the subadditivity of these generalized Kodaira dimensions for certain Kähler fibrations, which was originally obtained for Kodaira dimensions of algebraic fiber spaces by Kawamata and Viehweg. Our method is analytic and based on some new results in recent years. The crucial step in our proof is to prove an [Formula: see text] extension theorem for twisted pluricanonical sections on compact Kähler manifolds. Moreover, we also discuss the relation between two previous optimal [Formula: see text] extension theorems with singular weights on weakly pseudoconvex Kähler manifolds.

An isogeometric finite element approach to fibre-reinforced composites with fibre bending stiffness

In the modelling of fibre-reinforced composites, it is well established to consider the fibre direction in the stored energy in order to account for the transverse isotropy of the overall material, induced by a single family of fibres. However, this approach does not include any length scale and therefore lacks in the prediction of size effects that may occur from the fibre diameter or spacing. By making use of a generalised continuum model including non-symmetric stresses and couple-stresses, the gradient of the fibre direction vector can be taken into account as an additional parameter of the stored energy density function. As a consequence, the enhanced model considers the bending stiffness of the fibres and includes information on the material length scale. Along with additional material parameters, increased continuity requirements on the basis functions follow in the finite element analysis. The isogeometric finite element method provides a framework which can fulfil these requirements of the corresponding weak formulation. In the present contribution, the method is applied to two representative numerical examples. At first, the bending deformation of a cantilever beam is studied in order to analyse the influence of the fibre properties. An increasingly stiff response is observed as the fibre bending stiffness increases and as the fibre orientation aligns with the beam’s axis. Secondly, a fibre-reinforced cylindrical tube under a pure azimuthal shear deformation is considered. The corresponding simulation results are compared against a semi-analytical solution. It is shown that the isogeometric analysis yields highly accurate results for the boundary value problem under consideration.

Analytical determination of viscous permeability of hybrid fibrous reinforcements

• Transverse and longitudinal permeability models are developed for hybrid composites. • Permeability models are able to predict values in a wide range of cell porosity. • The model is valid for symmetrical and hybrid type cells and only depends on geometric parameters but not of fluid rheology. • Above 0.6 porosity value the models behave as symmetric. Transverse and longitudinal permeability for hybrid fibrous porous media were determined by solving Stokes and Darcy–Weisbach equations, respectively. A rectangular representative unit hybrid-cell with two sizes of fibre was used for solving one dimensional fluid flow to obtain velocity profile, flux, pressure drop and finally permeability. Both models were validated by using analytical models for permeability in symmetric cells reported in literature. Numerical simulations were performed using computational fluid dynamics to assess the permeability behaviour of several hybrid cells. Interesting results were found for several fibre radii ratios where the permeability changes differently for transverse and longitudinal models, so this model is based on fibre spacing and the change in diameter. It is notorious that for low porosity values and low fibre radii ratios, the transverse permeability decreases with respect to the constant fibre radii cell. It can be concluded that the permeability only depends on geometric variables, and the hybrid effect is more relevant in the permeability for porosities lower than 0.65.

Design and analysis of a 32 × 5 Gbps passive optical network employing FSO based protection at the distribution level☆

A cost efficient and reliable single mode fiber and free space optics based hybrid 32×5Gbps ultra dense wavelength division multiplexed-passive optical network architecture employing optical comb and polarization multiplexing is proposed. The proposed architecture is a step forward towards shifting the next generation wireless network traffic over existing passive optical network to achieve the optimum bandwidth, capacity, quality of service and cost efficiency for mobile subscribers. Self-restorable passive optical networks having fiber based feeder and distribution paths are widely researched in various studies in the past. However, to the best of our knowledge, a self-restorable passive optical network architecture employing free space optics based protection path has not been proposed so-far. The effect of varying polarization mode dispersion from 0.02 to 0.06ps.km-0.5 and the refractive index structure parameter of the Gamma-Gamma channel model from 5×10-16 to 5×10-12m-2/3 is evaluated. A techno-economic performance analysis of the architecture for downstream is performed by considering both the distribution and protection paths. It has been shown that the receiver sensitivity for a polarization mode dispersion of 0.06ps.km-0.5 is around -22dBm and for strong turbulence is around -20dBm.

ALGEBRAIC FIBER SPACES AND CURVATURE OF HIGHER DIRECT IMAGES

AbstractLet$p:X\rightarrow Y$be an algebraic fiber space, and let$L$be a line bundle on$X$. In this article, we obtain a curvature formula for the higher direct images of$\unicode[STIX]{x1D6FA}_{X/Y}^{i}\otimes L$restricted to a suitable Zariski open subset of$X$. Our results are particularly meaningful if$L$is semi-negatively curved on$X$and strictly negative or trivial on smooth fibers of$p$. Several applications are obtained, including a new proof of a result by Viehweg–Zuo in the context of a canonically polarized family of maximal variation and its version for Calabi–Yau families. The main feature of our approach is that the general curvature formulas we obtain allow us to bypass the use of ramified covers – and the complications that are induced by them.

WITHDRAWN: Beef tenderness evaluation using early post-mortem muscle nanostructure.

Ahead of Print article withdrawn by publisher.

Evaluation of the postmortem ageing process of beef M. semitendinosus based on ultrasound-assisted l-histidine treatment

This paper aimed to investigate the postmortem ageing process of beef M. semitendinosus (ST, just slaughtered muscles) using ultrasound-assisted l-histidine treatment. The treatments with different concentrations of l-histidine solutions (0.1%, 0.15%, and 0.2%, w/v) at 4 °C for 60 min were labeled “LH”, “MH” and “HH”, respectively. Furthermore, the corresponding treatments with the above l-histidine solutions for 55 min after ultrasound pretreatment for 5 min were labeled “ULH”, “UMH” and “UHH”, respectively. The results showed that the UMH group had the lowest Warner-Bratzler shear stress. The pH value of the HH and UHH groups was higher than that of the other groups (HH: 6.39 ± 0.02, UHH: 6.52 ± 0.03, P < 0.05). The MH and UMH groups showed large fiber spacing, cavities and fractures as well as obviously damaged myofibrils. In the UMH group, the soluble protein concentration (SPC) and caspase-3 activity were the highest, and the turbidity of actomyosin was the lowest. Surprisingly, the Ca2+-ATPase activity of actomyosin increased gradually with increasing concentrations of l-histidine solution. Therefore, the UMH treatment promoted the process of meat ageing, exhibiting the potential to be used by beef or other meat manufacturers to improve the production efficiency.

Angular sensing system based on Y-type twin-core fiber and reflective varied-line spacing grating fabricated by electron beam lithography

A varied-line spacing grating (VLSG) inscribed by electron beam lithography was proposed and used for an experimental demonstration of angular sensing. The designed VLSG central groove density was 655 L/mm, and it had an aluminized surface to reflect light. A Y-type twin-core fiber of 600 μm diameter cores connected with a collimator lens was used to input and collect reflected light from the VLSG. The Y-type fiber input and output paths were connected to a white light source and an optical spectrum analyzer, respectively. The fabricated quasi-continuous VLSG size was 70 × 30 mm, with a fixed 23° input angle. The reflected wavelength changed from 917.3 to 1656.9 nm as the incident light spot moved to different grating positions, with a displacement sensitivity of 14.812 nm/mm. As the input angle was adjusted from 23° to 35° in 1° increments, the spot location on the VLSG changed simultaneously, and the reflection wavelength peak positions changed from 917.3 to 1584.5 nm, with a sensitivity of 57.544 nm/° and linearity of 0.993.

Simulation studies on polarization modulated vertical cavity surface emitting laser for combined fiber and free space optical links

In this work, polarization property of Vertical Cavity Surface Emitting Laser (VCSEL) is investigated for 5 Gbps optical data transmission in a combined link comprising of Single Mode Fiber (SMF) and Free Space Optic (FSO) channel. The VCSEL considered for simulation is biased just above threshold with RZ current pulses to emit narrow polarized optical pulses. After 20 km SMF link, the received power is launched into two different paths using an optical splitter. It is received by an InGaAs PIN photodiode in one path and a coupling lens in other. A split ratio of 2%, provides the minimum power required for the SMF link to maintain a BER ≤10−12, based on the VCSEL considered in the study. The remaining 98 % of power is utilised for FSO transmission beyond the SMF link. The maximum FSO link distances under various loss combinations were found for the two polarized optical pulses, separately. For BER≤10−12, under the combined influence of all losses, an FSO link length of 130 m and 119 m, for x and y polarizations are predicted.

Investigation on the mechanical behavior of fiber-metal laminates based on polyvinyl chloride reinforced by 3D glass fibers

Fiber-Metal Laminates (FMLs) are new hybrid materials with a lightweight structure, excellent tensile and bending forces properties, as well as high impact resistance. In this paper, production and mechanical properties are investigated in FMLs made from the aluminum sheet as the core and polyvinyl chloride (PVC) thermoplastic reinforced by 3D glass fibers. The inside space of 3D glass fibers is filled with PVC powder and PVC films has been used for adherence layers to each other. FMLs produced under different temperatures, pressures, and processing time. The mechanical properties of FMLs, including their tensile and flexural strength, were investigated and evaluated. Based on the results, the temperature had the greatest influence on the mechanical properties of the samples. The highest tensile and flexural strengths were achieved for the FMLs that produced at 180 °C, 20 min, and pressure of 2.5 MPa, respectively equal to 112.8 MPa and 78.3 MPa. Scanning Electron Microscope (SEM) imaging of the fracture surfaces of the tensile and bending area of the flexural test shows that the best impregnation and bonding between the matrix material and fibers was established at 180 °C.

Development of light-transmitting concrete – A review

This paper provides an overview on the development of Light-transmitting Concrete (LTC). Concrete is improved in terms of transparency by installing optical fibres into the concrete. The application of LTC in building enables light transmission, which reduces light energy consumptions and carbon footprint, providing a more sustainable living environment. This paper also discusses the current development and application of LTC. Some of the previous research regarding the microstructure and mechanical properties of LTC in terms of compressive strength and light transmittance properties are also discussed. LTC has greater light transmittance with higher fibre volumetric fraction, smaller fibre diameter and spacing. However, the relationship between the factors and the light transmitting properties of LTC is yet to be investigated. Besides the fibre parameters, other environmental factors should also be considered to investigate the applicability and durability of LTC. There is still lack of investigation on the physical and mechanical properties of LTC especially in the applications for structural performance. Further research is required to investigate the fibre–matrix interfacial bond strength of LTC and measures should be taken to improve the mechanical strength of LTC. Besides buildings, there is also a research potential on the application of LTC on civil and infrastructure in terms of traffic safety.

How ultrasound combined with potassium alginate marination tenderizes old chicken breast meat: Possible mechanisms from tissue to protein

The combined effects of ultrasound (intensity of 15.6 W/cm2 and sonication for 5 min) with potassium alginate (PA) marination (UPA) on tenderizing old chicken breast meat, and possible mechanisms from tissue to protein, were investigated. UPA-treated meat exhibited the lowest moisture loss and shear force (optimized tenderness). The increased fiber space benefited PA invasion to form a heat-induced barrier for harder muscle contraction and avoid moisture withdrawal. Special scale-like structures of dried myofibrillar protein (MP) and the three-dimensional network induced by interactions between PA and MP increased the tenderness. UPA treatment induced stronger electrostatic repulsion between PA molecules and more β-sheet structures of MP, accompanied by a smallest size. The more easily heat-denatured myosin and looser myofibrils accelerated the temperature rise. More immobilized water restricted to myofibrils and moisture captured in the gel network promoted water retention. UPA treatment could be a promising technology to tenderize old chicken breast meat.