Application of active heat pulse method with fiber optic temperature sensing for estimation of wetting bulbs and water distribution in drip emitters.

Through the use of the Distributed Fiber Optic Temperature Measurement (DFOT) method, it is possible to measure the temperature in small intervals (on the order of centimeters) for long distances (on the order of kilometers) with a high temporal frequency and great accuracy. The heat pulse method consists of applying a known amount of heat to the soil and monitoring the temperature evolution, which is primarily dependent on the soil moisture content. The use of both methods, which is called the active heat pulse method with fiber optic temperature sensing (AHFO), allows accurate soil moisture content measurements. In order to experimentally study the wetting patterns, i.e. shape, size, and the water distribution, from a drip irrigation emitter, a soil column of 0.5 m of diameter and 0.6 m high was built. Inside the column, a fiber optic cable with a stainless steel sheath was placed forming three concentric helixes of diameters 0.2 m, 0.4 m and 0.6 m, leading to a 148 measurement point network. Before, during, and after the irrigation event, heat pulses were performed supplying electrical power of 20 W/m to the steel. The soil moisture content was measured with a capacitive sensor in one location at depths of 0.1 m, 0.2 m, 0.3 m and 0.4 m during the irrigation. It was also determined by the gravimetric method in several locations and depths before and right after the irrigation. The emitter bulb dimensions and shape evolution was satisfactorily measured during infiltration. Furthermore, some bulb's characteristics difficult to predict (e.g. preferential flow) were detected. The results point out that the AHFO is a useful tool to estimate the wetting pattern of drip irrigation emitters in soil columns and show a high potential for its use in the field.

Inorganic Nanoparticle-Modified Poly(Phenylene Sulphide)/ Carbon Fiber Laminates: Thermomechanical Behaviour

Carbon fiber (CF)-reinforced high-temperature thermoplastics such as poly(phenylene sulphide) (PPS) are widely used in structural composites for aerospace and automotive applications. The porosity of CF-reinforced polymers is a very important topic for practical applications since there is a direct correlation between void content and mechanical properties. In this study, inorganic fullerene-like tungsten disulphide (IF-WS2) lubricant nanoparticles were used to manufacture PPS/IF-WS2/CF laminates via melt-blending and hot-press processing, and the effect of IF-WS2 loading on the quality, thermal and mechanical behaviour of the hybrid composites was investigated. The addition of IF-WS2 improved fiber impregnation, resulting in lower degree of porosity and increased delamination resistance, compression and flexural properties; their reinforcement effect was greater at temperatures above the glass transition (Tg). IF-WS2 contents higher than 0.5 wt % increased Tg and the heat deflection temperature while reduced the coefficient of thermal expansion. The multiscale laminates exhibited higher ignition point and notably reduced peak heat release rate compared to PPS/CF. The coexistence of micro- and nano-scale fillers resulted in synergistic effects that enhanced the stiffness, strength, thermal conductivity and flame retardancy of the matrix. The results presented herein demonstrate that the IF-WS2 are very promising nanofillers to improve the thermomechanical properties of conventional thermoplastic/CF composites.

Photonic liquid crystal fiber intermodal interferometer

In this work, we present a novel interferometer based on liquid crystal and photonic crystal fiber technology. The objective of this project is the development of a tunable (switchable) modal (Mach-Zehnder) interferometer for optical communications or sensing. This interferometer has been manufactured splicing a short portion (between 15 and 30 mm) of photonic crystal fiber with two single mode fiber pigtails. The study shows a high sensitivity of the interferometer to the polarization of the launching light.

Polyolefin fiber-reinforced concrete enhanced with steel-hooked fibers in low proportions

Over the past few years, polyolefin fiber reinforced self-compacting concrete has shown high performance in both fresh and hardened state. Its fracture behavior for small deformations could be enhanced with a small amount of steel-hooked fibers, obtaining a hybrid fiber-reinforced concrete well suited for structural use. Four types of conventional fiber-reinforced concrete with steel and polyolefin fibers were produced on the basis of the same self-compacting concrete also manufactured as reference. These concrete mixtures were manufactured separately with the same fiber contents being subsequently used for two more hybrid mixtures. Fracture properties, in addition to fresh and mechanical properties, were assessed. The research showed both synergies (with the two types of fibers working together in the fracture processes) and an improvement of the orientation and distribution of the fibers on the fracture surface

Mapping variability of soil water content and flux across 1¿1000 m scales using the actively heated fiber optic method

The Actively Heated Fiber Optic (AHFO) method is shown to be capable of measuring soil water content several times per hour at 0.25 m spacing along cables of multiple kilometers in length. AHFO is based on distributed temperature sensing (DTS) observation of the heating and cooling of a buried fiber-optic cable resulting from an electrical impulse of energy delivered from the steel cable jacket. The results presented were collected from 750 m of cable buried in three 240 m colocated transects at 30, 60, and 90 cm depths in an agricultural field under center pivot irrigation. The calibration curve relating soil water content to the thermal response of the soil to a heat pulse of 10 W m−1 for 1 min duration was developed in the lab. This calibration was found applicable to the 30 and 60 cm depth cables, while the 90 cm depth cable illustrated the challenges presented by soil heterogeneity for this technique. This method was used to map with high resolution the variability of soil water content and fluxes induced by the nonuniformity of water application at the surface.

Infiltration of a photonic crystal fiber with cholesteric liquid crystal and blue phase

Photonic crystal fibers (PCF) have been selectively filled with a cholesteric liquid crystal (ChLC) with special interest in the blue phase (BP) of the liquid crystal. It has been observed thermal tuning of the guided light in the visible region. A dramatically enhance appears when the phase of the liquid crystal changes from cholesteric to blue phase I (BPI). When a thermal range of the blue phase I is achieved, no changes are observed while increasing temperature from BPI through BPII and to the isotropic phase.

DPSK signals demodulation based on a multimode fiber with a central dip

Differential Phase Shift Keying (DPSK) modulation format has been shown as a robust solution for next-generation optical transmission systems. One key device enabling such systems is a delay interferometer, converting the phase modulation signal into the intensity modulation signal to be detected by the photodiodes. Usually, a standard Mach-Zehnder interferometer (MZI) is used for demodulating a DPSK signal. In this paper, we develop an MZI which is based on all-fiber Multimode Interference (MI) structure: a multimode fiber (MMF) with a central dip, located between two single-mode fibers (SMFs) without any transition zones. The MI based MZI (MI-MZI) is more stable than the standard MZI as the two arms share the same MMF, reducing the impact of the external effects, such as temperature and others. Performance of this MI-MZI is analyzed theoretically and experimentally from transmission spectrum. Experimental results shows that high interference extinction ratio is obtained, which is far higher than that obtained from a normal graded-index based MI-MZI. Finally, by software simulation, we demonstrate that our proposed MI-MZI can be used for demodulating a 40 Gbps DPSK signal. The performance of the MI-MZI based DPSK receiver is analyzed from the sensitivity. Simulation results show that sensitivity of the proposed receiver is about -22.3 dBm for a BER of 10-15 and about -23.8 dBm for a BER of 10-9.

Multiscale-fiber-reinforced thermoplastic composites incorporating carbon nanotubes: A review

This article reviews recent literature on hierarchical thermoplastic-based composites that simultaneously incorporate carbon nanotubes (CNTs) and conventional microscale fibers, and discusses the structure?property relationships of the resulting hybrids. The mixing of multiple and multiscale constituents enables the preparation of materials with new or improved properties due to synergistic effects. By exploiting the outstanding mechanical, thermal and electrical properties of CNTs, a new generation of multifunctional high-performance composites suitable for a wide variety of applications can be developed.

Thermally tunable polarization by nanoparticle plasmonic resonance in photonic crystal fibers

A photonic crystal fiber selectively filled with silver nanoparticles dispersed in polydimethylsiloxane has been numerically studied via finite elements analysis. These nanoparticles possess a localized surface plasmon resonance in the visible region which depends on the refractive index of the surrounding medium. The refractive index of polydimethylsiloxane can be thermally tuned leading to the design of polarization tunable filters. Filters found with this setup show anisotropic attenuation of the x-polarization fundamental mode around ?x = 1200dB/cm remarkably higher than the y-polarization mode. Moreover, high fiber birefringence and birefringence reversal is observed in the spectral region of the plasmon.

Scalable high-order UWB pulse generation employing an FBG-based photonic superstructure

In this letter, we propose and experimentally demonstrate a compact, flexible, and scalable ultrawideband (UWB) generator based on the merge of phase-to-intensity conversion and pulse shaping employing an fiber Bragg Grating-based superstructure. Our approach offers the capacity for generating high-order UWB pulses by means of the combination of various low-order derivatives. Moreover, the scheme permits the implementation of binary and multilevel modulation formats. Experimental measurements of the generated UWB pulses, in both time and frequency domain, are presented revealing efficiency and a proper fit in terms of Federal Communications Commission settled standards.

Effect of level of fiber of the rearing phase diets on egg production, digestive tract traits, and body measurements of brown egg-laying hens fed diets differing in energy concentration

This research studied the effects of additional fiber in the rearing phase diets on egg production, gastrointestinal tract (GIT) traits, and body measurements of brown egg-laying hens fed diets varying in energy concentration from 17 to 46 wk of age. The experiment was completely randomized with 10 treatments arranged as a 5 × 2 factorial with 5 rearing phase diets and 2 laying phase diets. During the rearing phase, treatments consisted of a control diet based on cereals and soybean meal and 4 additional diets with a combination of 2 fiber sources (cereal straw and sugar beet pulp, SBP) at 2 levels (2 and 4%). During the laying phase, diets differed in energy content (2,650 vs. 2,750 kcal AMEn/kg) but had the same amino acid content per unit of energy. The rearing diet did not affect any production trait except egg production that was lower in birds fed SBP than in birds fed straw (91.6 and 94.1%, respectively; P < 0.05). Laying hens fed the high energy diet had lower feed intake (P < 0.001), better feed conversion (P < 0.01), and greater BW gain (P < 0.05) than hens fed the low energy diet but egg production and egg weight were not affected. At 46 wk of age, none of the GIT traits was affected by previous dietary treatment. At this age, hen BW was positively related with body length (r = 0.500; P < 0.01), tarsus length (r = 0.758; P < 0.001), and body mass index (r = 0.762; P < 0.001) but no effects of type of diet on these traits were detected. In summary, the inclusion of up to 4% of a fiber source in the rearing diets did not affect GIT development of the hens but SBP reduced egg production. An increase in the energy content of the laying phase diet reduced ADFI and improved feed efficiency but did not affect any of the other traits studied.

Physically-sound simulation of low-velocity impact on fiber reinforced laminates

A high-fidelity virtual tool for the numerical simulation of low-velocity impact damage in unidirectional composite laminates is proposed. A continuum material model for the simulation of intraply damage phenomena is implemented in a numerical scheme as a user subroutine of the commercially available Abaqus finite element package. Delaminations are simulated using of cohesive surfaces. The use of structured meshes, aligned with fiber directions allows the physically-sound simulation of matrix cracks parallel to fiber directions, and their interaction with the development of delaminations. The implementation of element erosion criteria and the application of intraply and interlaminar friction allow for the simulation of fiber splits and their entanglement, which in turn results in permanent indentation in the impacted laminate. It is shown that this simulation strategy gives sound results for impact energies bellow and above the Barely Visible Impact Damage threshold, up to laminate perforation conditions

Metabolic pathway engineering in cotton: Biosynthesis of polyhydroxybutyrate in fiber cells

Alcaligenes eutrophus genes encoding the enzymes, β-ketothiolase (phaA), acetoacetyl-CoA reductase (phaB), and polyhydroxyalkanoate synthase (phaC) catalyze the production of aliphatic polyester poly-d-(−)-3-hydroxybutyrate (PHB) from acetyl-CoA. PHB is a thermoplastic polymer that may modify fiber properties when synthesized in cotton. Endogenous β-ketothiolase activity is present in cotton fibers. Hence cotton was transformed with engineered phaB and phaC genes by particle bombardment, and transgenic plants were selected based on marker gene, β-glucuronidase (GUS), expression. Fibers of 10 transgenic plants expressed phaB gene, while eight plants expressed both phaB and phaC genes. Electron microscopy examination of fibers expressing both genes indicated the presence of electron-lucent granules in the cytoplasm. High pressure liquid chromatography, gas chromatography, and mass spectrometry evidence suggested that the new polymer produced in transgenic fibers is PHB. Sixty-six percent of the PHB in fibers is in the molecular mass range of 0.6 × 106 to 1.8 × 106 Da. The presence of PHB granules in transgenic fibers resulted in measurable changes of thermal properties. The fibers exhibited better insulating characteristics. The rate of heat uptake and cooling was slower in transgenic fibers, resulting in higher heat capacity. These data show that metabolic pathway engineering in cotton may enhance fiber properties by incorporating new traits from other genetic sources. This is an important step toward producing new generation fibers for the textile industry.

Phospholipase Cβ4 is specifically involved in climbing fiber synapse elimination in the developing cerebellum

Elimination of excess climbing fiber (CF)–Purkinje cell synapses during cerebellar development involves a signaling pathway that includes type 1 metabotropic glutamate receptor, Gαq, and the γ isoform of protein kinase C. To identify phospholipase C (PLC) isoforms involved in this process, we generated mice deficient in PLCβ4, one of two major isoforms expressed in Purkinje cells. PLCβ4 mutant mice are viable but exhibit locomotor ataxia. Their cerebellar histology, parallel fiber synapse formation, and basic electrophysiology appear normal. However, developmental elimination of multiple CF innervation clearly is impaired in the rostral portion of the cerebellar vermis, in which PLCβ4 mRNA is predominantly expressed. By contrast, CF synapse elimination is normal in the caudal cerebellum, in which low levels of PLCβ4 mRNA but reciprocally high levels of PLCβ3 mRNA are found. These results indicate that PLCβ4 transduces signals that are required for CF synapse elimination in the rostral cerebellum.

GTPase Activity and Biochemical Characterization of a Recombinant Cotton Fiber Annexin1

A cDNA encoding annexin was isolated from a cotton (Gossypium hirsutum) fiber cDNA library. The cDNA was expressed in Escherichia coli, and the resultant recombinant protein was purified. We then investigated some biochemical properties of the recombinant annexin based on the current understanding of plant annexins. An “add-back experiment” was performed to study the effect of the recombinant annexin on β-glucan synthase activity, but no effect was found. However, it was found that the recombinant annexin could display ATPase/GTPase activities. The recombinant annexin showed much higher GTPase than ATPase activity. Mg2+ was essential for these activities, whereas a high concentration of Ca2+ was inhibitory. A photolabeling assay showed that this annexin could bind GTP more specifically than ATP. The GTP-binding site on the annexin was mapped into the carboxyl-terminal fourth repeat of annexin from the photolabeling experiment using domain-deletion mutants of this annexin. Northern-blot analysis showed that the annexin gene was highly expressed in the elongation stages of cotton fiber differentiation, suggesting a role of this annexin in cell elongation.