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Anisotropy of mechanical property is an important feature influencing the service performance of titanium (Ti) alloy tube component. In this work, it is found that the hot flow formed Ti alloy tube exhibits higher yield strength along circumferential direction (CD), and larger elongation along rolling direction (RD), presenting significant anisotropy. Subsequently, the quantitative characteristics and underlying mechanism of the property anisotropy were revealed by analyzing the slip, damage and fracture behavior under the combined effects of the spun {0002} basal texture and fibrous microstructure for different loading directions. The results showed that the prismatic slip in primary α grain is the dominant deformation mechanism for both loading directions at the yielding stage. The prismatic slip is harder under CD loading, which makes CD loading present higher yield strength than RD loading. Additionally, the yield anisotropy can be quantified through the inverse ratio of the averaged Schmid Factor of the activated prismatic slip under different loading directions. As for the plasticity anisotropy, the harder and slower slip development under CD loading causes that the CD loading presents larger external force and normal stress on slip plane, thus leading to more significant cleavage fracture than RD loading. Moreover, the micro-crack path under RD loading is more tortuous than CD loading because the fibrous microstructure is elongated along RD, which may suppress the macro fracture under RD loading. These results suggest that weakening the texture and fibrous morphology of microstructure is critical to reduce the differences in slip, damage and fracture behavior along different directions, alleviate the property anisotropy and optimize the service performance of Ti alloy tube formed by hot flow forming.

In order to establish a degumming damage identification method for hidden frame glass curtain wall (HFSGCW) which can be used in engineering practice. In this paper, a damage identification method based on discrete wavelet analysis (DWT) combined with vibration transmissibility is proposed to detect structural adhesive of HFSGCW. The vibration transmissibility is used as damage parameter to characterize the damage degree of structural adhesive. The results show that rubber hammer is an effective method to obtain accurate vibration spectrum of glass plate. In order to obtain accurate vibration transmissivity, it is suggested to select the edge of glass plate as the measuring point. Under six different structural adhesive damage conditions, the damage parameters of vibration transfer rate increase with the increase of structural adhesive damage degree. The damage parameters of vibration transmissibility obtained by DWT can identify the initial small damage of structural adhesive. A safety state evaluation model of HFSGCW glass plate based on vibration transfer rate is proposed. It is of great significance to evaluate the safety state of HFSGCW glass plate.

The poor conductivity of metal-organic frameworks (MOFs) has greatly restricted their widespread application in water splitting. Herein, the Ni-MOF is used to be a precursor to support a stable three-dimensional structure, high surface areas and to prepare various contents of Pd doped Ni alloys (Pd/Ni-1, Pd/Ni-2 and Pd/Ni-3). The hydrogen evolution reaction (HER) activity of samples is compared in alkaline electrolyte (1.0 M KOH). As-prepared catalysts exhibit uniform dispersion, good crystallinity, high purity and a small particle size according to the physical characterization. What is more, based on the electrochemical characterization, Pd/Ni-3 has an exclellent HER performances with a lower overpotential (50 mV in base at 10 mA·cm−2), smaller Tafel slope (102 mV·dec−1) and more positive initial potential (ƞ at 1 mA·cm−2; Δ ƞ = 660 mV) than that of Ni-MOF. The reduction percentage of resistance charge transfer (Rct) relative to Ni-MOF of Pd/Ni-3 is up to 95.6%. This work may offer guidance to make up the low conductivity of MOF for HER in alkaline electrolyte.

Revealing the development of microstructural inhomogeneity in the multi-pass flow forming of titanium alloy components is of great significance to the microstructure control and property tailoring. To this end, the microstructural inhomogeneity of TA15 alloy spun cylindrical parts was analyzed based on the deformation history. The results indicate that the material underwent significant compressive strain in the normal direction (ND), tension strain in the rolling and circumferential directions (RD and CD), while tension strain in the CD is slightly small due to the limited material flow in this direction. These strain characteristics make the microstructure, especially the primary α (αp), present different morphologies in the different planes of the part. Meanwhile, the combined effects of inhomogeneous deformation and temperature distribution in the ND also cause the inhomogeneity of microstructure morphology and parameters in this direction. Quantitative analyses show that with the forming pass increasing, the aspect ratio of αp increases most in the normal-rolling plane, then in the normal-circumferential plane and least in the circumferential-rolling plane, whereas αp content decreases in an opposite trend. Along the ND, the aspect ratio and content of αp is relatively high in the outer and inner surface areas but lowest in the central area, and these inhomogeneous characteristics can be gradually diminished with the forming pass increasing. Furthermore, the variation of hardness inhomogeneity factor indicates that a four-pass forming with the total reduction ratio of 63% could obtain a homogenous microstructure along the ND of the TA15 alloy spun cylindrical part.

A sensor was fabricated based on optical gas sensing, the sensitivity of tin oxide to methane via surface adsorption and electromagnetic theory. A 62.5/125 μm standard multimode fibre (MMF) and a 9/125 μm standard single-mode fibre (SMF) were spliced to fabricate a core diameter mismatch-based optical fibre methane sensor with an MM-SM-MM structure. The exposed fibre core areas were coated with graphene-doped tin oxide such that a novel graphene-based optical fibre methane sensor was fabricated. The experimental results show that the sensor exhibited a better linear fitting for greater reproducibility in the detection of low concentrations of methane than did the D-type gas sensor reported previously by the same authors.

How to form high-quality transverse inner ribs through power spinning is a key issue for complicated integrated curved generatrix parts with transverse inner ribs. In this study, the forming characteristics and laws during the power spinning process were investigated using a finite element simulation based on the orthogonal design method. The results show that the transverse inner rib distributes homogeneously along the circumferential direction but inhomogeneously along the generatrix direction. Depressions occur easily in the middle zone of the rib (MZR). The roller nose radius is the most significant parameter of the MZR underfill degree. A larger roller nose radius is helpful to decrease the MZR underfill degree. Furthermore, the preformed billet thickness also plays a vital role in the underfill degree of the front zone of the rib and the back zone of the rib, as well as the depression degree of the outer surface of the rib. By combining the rib-filling characteristics and laws, the optimized forming process window for obtaining high-quality inner ribs was obtained by regression analysis, thus laying a basis for improving the forming quality of curved generatrix parts with transverse inner ribs in power spinning.

A combination of scanning electron microscopy and electron backscatter diffraction is used to investigate the deformation in the fatigue crack tip plastic zone and its role in the crack propagation of Ti-6Al-2Zr-1Mo-1V alloy with a tri-modal microstructure. The results show that heterogenous slip and secondary micro-cracks are the main features of the fatigue crack tip plastic zone. These features play important roles in fatigue crack propagation. In particular, the unique lamellar α in the tri-modal microstructure can deflect and delay the crack propagation effectively, thus, improving the fatigue life.

Multi-pass flow forming processes are one of the major approaches to producing thin-walled titanium cylindrical parts with large cross-sections in which microstructure characteristics have a significant effect on the tailoring of desirable properties. In this study, the microstructure evolution of the Ti-6Al-2Zr-1Mo-1V alloy and its mechanism in a multi-pass flow forming process are systematically studied based on the deformation characteristics during the process. The results show that waved grains formed in the process are due to the compressive stress in the rolling direction (RD) and the non-uniform stress field in the deformation area. With the compression and shear deformation induced in multi-pass flow forming, non-standard {0002} basal plane texture is formed whose {0002} poles are tilted from the normal direction (ND) to the RD and the circumferential direction (CD) with an angle of 20° and 30°, respectively. It is found that α grains are refined by two mechanisms, viz., continuous dynamic recrystallization (CDRX) and deformation-induced intense and localized shearing (DILS). CDRX mainly promotes secondary α grain refinement, while DILS has significant effects on primary α grain refinement under the larger deformation and on secondary α grain refinement during the entire process. Meanwhile, the grains refined by DILS with different orientations facilitate further deformation. This effect of grain refinement leads to improvement of the yield strength in the RD and the CD by 12.42% and 19.05%, respectively, compared annealed samples of the cylindrical part with the original one. These findings provide a basis for microstructure control and property tailoring of Ti-6Al-2Zr-1Mo-1V cylindrical parts in flow forming processes.

High solid anaerobic digestion (HSAD) was an emerging bioconversion technology which had the advantages of small digester, less digestate and low heating energy. A one-stage anaerobic system in CSTR by inoculating activated sludge of simultaneous propionate degradation and methanogenesis was proposed to improve the high-solid digestion performance and to stabilize the reaction process. Semi-continuous mode was successfully used to perform HSAD from cellulosic ethanol whole stillage at an initial substrate loading of 15.4% (w/w) dry matter content with different OLRs from 1.5 to 5.0 gVS·L−1 d−1 at an HRT of 30 days. The average methane yield during whole digestion reached 349.9 mL⋅gVS−1 with a total VS removal rate of 61.3%. The acclimation mechanism of multifunctional activated sludge was also explored by analyzing the functional property, physiological activity and microbial community structure. The results indicated the feasibility and efficiency of multifunctional activated sludge in a semi-continuous high-solid stirred tank reactor system.

Vitamin A is easily degraded by environmental factors. Therefore, it is very important to add antioxidants during Vitamin A production. In the past, ethoxyquin (EQ) was widely used, but recent studies have found that it has potential toxicity. Therefore, in this study, we evaluated the antioxidant activities of 4 antioxidants in vitro: EQ, butylated hydroxytoluene, α-tocopherol and L-ascorbic acid sodium salt (Vitamin C sodium). In vitro experiments showed that Vitamin C sodium had better antioxidant capacity. Then, we explored the effects of different antioxidant types of Vitamin A on the growth performance, immune function and antioxidant capacity of weaned pigs. In total, 288 weaned piglets with an initial mean BW of 8.34 ± 0.02 kg at 30 days old were randomly divided into three groups with four replicates and 24 piglets per replicate for 35 days of feeding. The experimental diets were as follows: i) basal diet without external Vitamin A (NC); ii) basal diet supplemented with 12000 IU/kg EQ Vitamin A and iii) basal diet supplemented with 12000 IU/kg Vitamin C sodium Vitamin A. On day 36, two pigs from each replicate were selected to collect serum samples. The in vivo results showed that pigs in the EQ Vitamin A and Vitamin C sodium Vitamin A groups had significantly higher final weight and average daily gain (P

The ATLAS experiment at CERN is scheduled to replace the innermost station of its Muon Spectrometer in the forward region during its Phase-I upgrade in order to enhance the capabilities on triggering and tracking of high transverse momentum muons towards high luminosity LHC runs. The New Small Wheel (NSW), a completely new detector system to be built, is composed of two novel gaseous detectors: Micro-mesh Gaseous Structure (Micromegas) and the small-strip Thin Gap Chamber (sTGC). The sTGC sub-system is the primary trigger detector. It will be equipped with radiation-tolerant, low-latency electronics for reading out over 400,000 channels to identify the bunch crossing time of proton-proton collisions spaced by 25 ns, as well as to collect fine strip charge information for the charged track reconstruction. In this paper, we present the design and development of a set of Front-End Boards (FEBs) for the sTGC detector system. The major challenges in the design will be discussed. These include the accommodation of a few hundred readout channels per single board in a very constrained space, a tight requirement for the Electrostatic Discharge (ESD) protection of 130 nm ASICs, and customized analog input circuits to handle the high rate and high charge signals from the sTGC detectors. Moreover, the FEBs have to incorporate a few hundred parallel inter-chip links at 320 Mbps and several low-latency serial links operating at 4.8 Gbps for the Level-1 and trigger data readout. The characterization of the FEBs performance, both off-detector and on-detector, will be shown.

Energy-efficient and environment-friendly solid-state magnetic refrigeration requires materials with extraordinary magnetocaloric properties. We report the plateau-like magnetocaloric effect activated by tripled magnetic cell in layered intermetallic TbMn2-xCoxSi2 compounds, and the consequent large refrigerant capacity. Substitution of Mn with Co significantly modified the magnetic properties evidenced by two successive ferromagnetic first-order transitions and strong magneto-elasticity as well as significant contraction of the unit cell. Detailed neutron diffraction investigations have established the formation of a tripled magnetic unit cell structure at the temperature range between two magnetic transitions. The overlapping entropy curves near the two transition temperatures results in a plateau-like magnetocaloric effect and enhanced refrigerant capacity. Existence of this special magnetic cell also leads to a variety of interesting physical properties, including a significant drop in resistance and pronounced anomalies in the heat capacity, as well as different responses of the two transition temperatures to an applied magnetic field. The impact of the formation of a tripled magnetic cell on the physical properties is highly unusual for magnetic alloys and merits expanded investigation of this class of magnetic materials to explore for novel applications.

We analyze the mechanism by which tin oxide can be utilized for the optical sensing of methane gas via surface adsorption and electromagnetic theory. Single-mode optical fibers with core diameters of 9 μm and cladding diameters of 12 μm were used. A 15 mm-long segment of each optical fiber was polished to the core via wheel side-polishing; the exposed fiber core areas were coated with graphene-doped tin oxide such that a novel graphene-based optical fiber methane sensor was fabricated. The experimental results show that the sensor exhibits excellent linear fitting and reproducibility, making it useful for the detection of low concentrations of methane.

The effect of initial tempers with different characteristics of precipitates and contents of supersaturated solute atoms, including the homogenized, peak–aged and over–aged conditions, on the tensile creep behavior of WE43 alloy has been investigated at 523 K. Results show that the peak–aged alloy at 523 K obtained superior creep resistance than the homogenized, peak–aged at 498 K and over–aged at 523 K alloy. A uniform dispersion of β precipitates was dynamically formed within steady–stage creep microstructure of the homogenized WE43 alloy after creep deformation of 200 h. It is found that the precipitate size and distribution is similar with the alloy aged equal time without the applied stress. In addition, the WE43 alloy in all tempers obtains similar precipitate size and distribution in their steady–stage creep microstructures. Therefore, it is inferred that the various initial tempers mainly affect the primary creep stage. Furthermore, numerous dislocations were detected between precipitates and the stress exponent n is 4.5, which is close to 5. Thereby, dislocation climb is suggested to be the creep mechanism. The reason for the peak–aged alloy at 523 K obtained superior creep resistance is that the initial uniform dispersion of β″ and β′ precipitates have smaller precipitate size and higher precipitate density than that of the homogenized and over–aged alloy, which are more effectively to hider dislocation climb. However, a deterioration of creep resistance was occurred in the peak−aged alloy at 498 K due to precipitate recovery when crept at 523 K. As a consequence, WE43 alloy in peak–aged temper at 523 K achieves the highest creep resistance.

The effect of cold plastic deformation by multi-directional forging prior to artificial aging treatment on the microstructure and mechanical properties of WE43 alloy was investigated. The results show that the pre-deformation produced high density of dislocations and deformation twins. After peak-aging treatment at 200 °C, the pre-deformation reduced the average size of fine β″ and β′ precipitates and promoted the formation of β 1 phase. Additionally, spheroid–shaped precipitates formed at twin boundaries and the deformation twins were thermally stable during the aging treatment. Mechanical properties reveal that the tensile yield and ultimate strength is significantly enhanced from 191±3 MPa to 270±15 MPa and 278±5 MPa to 320±18 MPa, respectively.

Supplemental material, DS_10.1177_0022034519864519 for MiR-361-3p/Nfat5 Signaling Axis Controls Cementoblast Differentiation by H.Q. Liao, H. Liu, H.L. Sun, J.B. Xiang, X.X. Wang, C.X. Jiang, L. Ma and Z.G. Cao in Journal of Dental Research

Aluminum alloy thin sheets are widely used to produce light-weight high-strength components and the sheets are generally quenched before forming (Q-F) to improve the final mechanical properties of components. However, the distortion in quenching will significantly affect the quality and stability of the following forming process. In this study, the distortion behavior of 2219 aluminum alloy thin sheets and its forming mechanism in quenching process were investigated through experiments and finite element analysis (FEA). The results indicate that, the quenched thin sheets basically present three distortion modes, namely saddle-shape, shovel-shape and arch-shape. The distortion modes of the quenched thin sheets are determined by the bending modes of distortion zone which is the zone of the thin sheet near the water surface. When the bending mode is one-half sine wave, the quenching thin sheets always show saddle-shape. However, for the cases where the bending mode changes to three-half sine wave and the bending of distortion zone is suppressed, the quenching thin sheets show shovel-shaped and arch-shaped distortion modes, respectively. The reasons behind the variations of the bending mode are finally analyzed based on a buckling criterion under laterally constrained conditions. These results will provide an in-depth understanding of quenching distortion behavior and lay a basic guidance for controlling the distortion of thin sheets in quenching process.

Dynamic recrystallization (DRX) plays great roles in the microstructure refinement and property improvement during hot working of titanium alloys. Various deformation modes in hot working may greatly affect the DRX mechanism and kinetics, but which has not attracted enough attention. In this work, the DRX mechanism and kinetics of titanium alloy in hot compression deformation (CD) and shear deformation (SD) were comparatively investigated by combining the electron backscatter diffraction technique and crystal plastic finite element models. The results show that discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) coexist in both of CD and SD, while their dominant mechanism and kinetics of DRX are quite different. These differences are found to be strongly dependent on the slip behavior and resulting misorientation development in each deformation mode. In CD, the smaller contribution ratios of basal and pyram as well as the gradual formation of {0002} basal texture suppress the lattice rotation and reduce the long-range misorientation gradient (MOG). As a result, the dominant DRX mechanism changes from CDRX to DDRX with strain in CD. However, SD presents much higher contribution ratios of basal and pyram compared with CD, and the c-axes of most grains are perpendicular to the direction of shear stress. These greatly improve the lattice rotation and long-range MOG, which makes CDRX always prevail and present larger driving force in SD. Moreover, higher contribution ratio of pyram slip in SD also improves the kernel average misorientation, and thus provides larger driving force for DDRX in SD than in CD. These factors make SD present faster DRX kinetics and thus raising the DRX fraction by 10% and grain size homogeneity by 32% compared with CD. These results suggest that the deformation condition and mode should be well designed for obtaining more refined and homogeneous microstructure in the hot working of titanium alloy components.

Compared with conventional identification methods, DNA-based genetic approaches such as single nucleotide polymorphisms (SNPs) and satellites are much more reliable for pig identification and meat traceability. In this study, multiallelic amplification fragments with multiple SNPs, incorporating the advantages of both SNPs and microsatellites, were explored for the first time for pig identification and meat traceability. Primer pairs for multiallelic fragments and their optimal SNPs were successfully selected and used for identification of individuals from Suzhong and Duroc populations. Meanwhile, the combined panel of the above mentioned primer pairs together with their optimal SNPs for Suzhong and/or Duroc pigs were validated for identification of the hybrids (Suzhong×Duroc). Therefore, we have successfully selected multiallelic amplification fragments with multiple SNPs to identify pigs and their meat samples from Suzhong, Duroc or their hybrids. Our study demonstrates that our method is more powerful for pig identification or meat traceability than SNPs or microsatellites.

Cotton is an important economic crop worldwide; its fiber, commonly known as cotton lint, is the main natural source for the textile industry. Sixty chloroplast microsatellites were identified and characterized from the complete sequence of the Gossypium hirsutum chloroplast genome using a bioinformatic approach. Twenty chloroplast microsatellite loci were polymorphic in the 66 Gossypium germplasm accessions. A total of 85 alleles were detected, with allele numbers varying from 2-7 per locus. Polymorphism information content varied from 0.02-0.66, with a mean of 0.48. Additionally, transferability of the 20 polymorphic chloroplast microsatellite primers was evaluated in other 31 Gossypium species. Sixteen markers were successfully amplified across all species tested, while the remaining 4 markers cross-amplified in most species tested. These polymorphic chloroplast microsatellite markers may be useful tool for studies of individual identification, genetic diversity, evolution, conservation genetics, and molecular breeding in Gossypium.

Planarians, which have a large population of stem cells called neoblasts, are molecularly tractable model systems used in the study of regeneration. However, planarians have strong resistance to hunger and have developed growth arrest strategies. For example, they can change their size and undergo growth regression during starvation periods. The results of the current study show that the microRNA, miR-71b, and the insulin/IGF-1 signaling pathway have important functions in the development of starvation-induced planarians. We demonstrate tissue-specific expression of miR-71b using in situ hybridization. By employing real-time polymerase chain reaction, we provide evidence that miR-71b is upregulated in starvation-induced planarians. Furthermore, we validate and verify the target genes of miR-71b.

Summary Objective Previous studies have shown that Transforming growth factor-β (TGF-β)/TGFβRII-Smad3 signaling is involved in articular cartilage homeostasis. However, the role of TGF-β/ALK5 signaling in articular cartilage homeostasis has not been fully defined. In this study, a combination of in vitro and in vivo approaches was used to elucidate the role of ALK5 signaling in articular cartilage homeostasis and the development of osteoarthritis (OA). Design Mice with inducible cartilage-specific deletion of Alk5 were generated to assess the role of ALK5 in OA development. Alterations in cartilage structure were evaluated histologically. The expressions of genes associated with articular cartilage homeostasis and TGF-β signaling were analyzed by qRT-PCR, western blotting and immunohistochemistry. The chondrocyte apoptosis was detected by TUNEL staining and immunohistochemistry. In addition, the molecular mechanism underlying the effects of TGF-β/ALK5 signaling on articular cartilage homeostasis was explored by analyzing the TGF-β/ALK5 signaling-induced expression of proteoglycan 4 (PRG4) using specific inhibitors. Results Postnatal cartilage-specific deletion of Alk5 induced an OA-like phenotype with degradation of articular cartilage, synovial hyperplasia, osteophyte formation, subchondral sclerosis, as well as enhanced chondrocyte apoptosis, overproduction of catabolic factors, and decreased expressions of anabolic factors in chondrocytes. In addition, the expressions of PRG4 mRNA and protein were decreased in Alk5 conditional knockout mice. Furthermore, our results showed, for the first time, that TGF-β/ALK5 signaling regulated PRG4 expression partially through the protein kinase A (PKA)-CREB signaling pathway. Conclusions TGF-β/ALK5 signaling maintains articular cartilage homeostasis, in part, by upregulating PRG4 expression through the PKA-CREB signaling pathway in articular chondrocytes.

Eurytrema pancreaticum is one of the most common trematodes of cattle and sheep, and also infects humans occasionally, causing great economic losses and medical costs. In this study, the sequences of the complete nuclear ribosomal DNA (rDNA) repeat units of five E. pancreaticum individuals were determined for the first time. They were 8306–8310 bp in length, including the small subunit (18S) rDNA, internal transcribed spacer 1 (ITS1), 5.8S rDNA, internal transcribed spacer 2 (ITS2), large subunit (28S) rDNA and intergenic spacer (IGS). There were no length variations in any of the investigated 18S (1996 bp), ITS1 (1103 bp), 5.8S (160 bp), ITS2 (231 bp) or 28S (3669 bp) rDNA sequences, whereas the IGS rDNA sequences of E. pancreaticum had a 4-bp length variation, ranging from 1147 to 1151 bp. The intraspecific variations within E. pancreaticum were 0–0.2% for 18S rDNA, 0–0.5% for ITS1, 0% for 5.8S rDNA and ITS2, 0–0.2% for 28S rDNA and 2.9–20.2% for IGS. There were nine types of repeat sequences in ITS1, two types in 28S rDNA, but none in IGS. A phylogenetic analysis based on the 18S rDNA sequences classified E. pancreaticum in the family Dicrocoeliidae of Plagiorchiata, closely related to the suborder Opisthorchiata. These results provide useful information for the further study of Dicrocoeliidae trematodes.

A 2D forward model driven by advection-diffusion equation in plane and linear stack model in vertical direction was designed to simulate fluvial-dominated delta system in North-Sea area. Two techniques are applied as an attempt to close the gap between stratigraphic forward simulation and observation. First, the discharge model for basin (DMB) was utilized to generate a reasonable initial guess of discharge and sediment concentration parameters. Discharge was described as a function of catchment area, volatility, and the precipitation that falls within the area. Sediment concentration is calculated based on a relationship of liquid discharge, large-scale relief and basin temperature. Second, an integrated inverse workflow was applied to calibrate the forward model to hard data. Geomorphological information extracted from seismic data, porosity, thickness and stacking pattern extracted from well data are utilized to build objective function. The simulation result was converted to acoustic impedance profile and compared with seismic inversion result. Remarkable resemblance between forward simulation and seismic inversion had been found. This research demonstrates the potential of integrated quantitative geological and geophysical interpretation and paves the road for future stratigraphic modeling optimization. It also provides some clues of reducing gap between geological concepts and geophysical observation.

Phosphorus (P) is a main limiting factor for agricultural production, but overusing P fertilizer has brought serious environmental damages in China. Improving P acquisition efficiency of agricultural crops is an urgent topic. It has been proven repeatedly that arbuscular mycorrhizal fungi (AMF) and genetic diversity within one crop plant can play important roles in P uptake by crops. The main objective of this thesis was to understand the role of the arbuscular mycorrhizal symbiosis in P acquisition efficiency of different maize varieties. The specific objectives were to test: 1) how P uptake by maize varieties responds to colonization by the native AMF community in the field; and 2) whether AMF hyphae take up P for plants from phytate which is the most abundant organic P form in soil; 3) whether mixing maize cultivars can improve maize productivity and whether AMF can play a role in this system; and 4) how AMF species (or community) legacy affects successional maize growth. In this thesis, I combined field experiments and greenhouse experiments and made use of maize genetic diversity and (native) AMF to improve P (including inorganic and organic P) acquisition. The effects of one single AMF species on maize growth and nutrient uptake have been well studied, but how maize varieties respond to the native AMF community has been insufficiently studied. In Chapter 2, I focused on how maize varieties responded to the native AMF community by using rotated cores in the field, to compare mycorrhizal responsiveness among 20 maize varieties and the difference of the AMF native community of four maize varieties (two old landraces and two modern hybrids). The results indicated that, 1) increased P fertilizer significantly reduced mycorrhizal responsiveness in the field; 2) a complicated relationship exists between mycorrhizal responsiveness in the field and pot experiment; 3) there was no significant difference between old and modern maize varieties in terms of mycorrhizal responsiveness and colonization; 4) there were only small differences in AMF community composition among the four maize varieties. By comparing mycorrhizal responsiveness of maize varieties between in the pot experiment and in the field experiment (with in-growth cores), I found mycorrhizal responsiveness of maize varieties in the pot experiment was significantly larger than that in the field experiment. Thus, mycorrhizal responsiveness of varieties within one cereal plant species tested classically in pots may not present their realistically mycorrhizal responsiveness in field. Phytate is the most abundant form of organic P in soil. To explore the potential of phytate utilization by plants is agriculturally and environmentally essential. Increased P nutrition of mycorrhizal plants derived from phytate has been reported, indicating that phytate can be a potential P source. However, earlier studies assessed phytate use by using acid phosphatase rather than phytase, and did not consider that phytate adsorption could lead to phosphate release. Thus, I investigated the effect of mycorrhizal hyphae-mediated phytase activity on P uptake by maize in Chapter 3. I conducted a rhizobox experiment to explore phytate use by mycorrhizal hyphae for two maize varieties. The results showed that: 1) phytate addition increased phytase and acid phosphatase activity, and resulted in increased P uptake and plant biomass; 2) the increase in P uptake and biomass were correlated with the increase of phytase activity but not with the increase of acid phosphatase activity; 3) lower phytate addition rate increased, but higher addition rates decreased hyphal length density. I conclude that P from phytate can be used by mycorrhizal plants, but that the phytate contribution to plant nutrition is likely limited. Phytase activity is a more relevant indicator to assess phytate use. In addition, there was a significant interaction between maize varieties and AMF species in taking up P from phytate, which implies there is a possibility to combine different maize varieties to increase total yield using phytate. Besides, I used an empirical relationship to assess phosphate release due to phytate addition. My calculation implies that phosphate desorption cannot be ignored when assessing phytate use, particularly when a large amount of phytate is applied as a P source. In multispecies natural ecosystems, AMF can play a key role in enhancing plant productivity. However, their role in enhancing crop productivity in mixed cropping systems is still poorly understood. In Chapter 4, I conducted both greenhouse and field experiments to investigate whether mixing maize varieties with different P acquisition strategies could lead to overyielding, and what roles AMF play in this system with two maize varieties. The results showed that mixing maize varieties resulted in overyielding, both in P uptake and shoot biomass, but only when plants were mycorrhizal. At the same time, I found higher hyphal length density and higher AMF diversity in mixtures compared to the monocultures in the field experiment, and higher colonization rate and higher hyphal length density in mixtures in the pot experiment. Thus, I propose that overyielding by mixing maize varieties might be due to increased mycorrhizal performance leading to more P uptake. I also used the partitioning formula to calculate the contribution through the selection effect and complementarity effect to overyielding. I found that the increase of the total yield and P uptake in mixtures was largely due to complementarity effect, implying that relative overyielding and enhanced P uptake were not due to enhanced competitive ability by the larger variety. The results of Chapter 4 suggest that mixing mycorrhizal maize varieties might be beneficial for enhancing productivity and P uptake efficiency. Plant - soil feedback experiments have shown that AMF can play a crucial role in determining the direction and magnitude of that feedback. Most studies investigated plant - soil feedback dynamics between different plant species. However, it is unknown to what extent one variety of an agricultural crop can affect the performance of another variety of that same crop through plant - soil feedback. In Chapter 5, I carried out a two-phase experiment in a greenhouse, including conditioning phase and test phase to determine plant - soil feedbacks in the absence and presence of AMF species or community, to test the effects of AMF on feedback dynamics. The results in Chapter 5 showed that: 1) in the conditioning phase, both maize varieties were differentially influenced by different AMF species compared to non-mycorrhizal control; 2) in the feedback phase, non-mycorrhizal maize exhibited negative feedback dynamics for biomass and P-uptake; 3) on the feedback phase, mycorrhizal maize generally exhibited positive feedback dynamics for biomass and P-uptake. The interaction coefficient was largest with the mixture of three different AMF species. The interaction coefficient for shoot and P uptake were significantly correlated with the coefficient for mycorrhizal colonization. These results imply that different maize varieties are affected differently by different AMF species, thereby influencing the productivity of the subsequent maize variety. The results also raise questions how AMF influence rhizosphere biota and how maize varieties may select more beneficial AMF. In Chapter 6, I integrate the results from previous chapters. I discuss possible relationships between (negative) plant - soil feedback effect (due to pathogen) and the mycorrhizal effect on overyielding and improved P uptake due to mixing maize varieties (compared to the monoculture). I also discuss the linkage between phosphorus acquisition efficiency and mycorrhizal responsiveness within one crop species, and the relationship between plant genetic diversity and plant - soil feedback effects, and try to come up with a conceptual model how mixing maize varieties in the presence of AMF could be beneficial.

Gossypium tomentosum is a wild allotetraploid species with the (AD)5 genome. It is characterized by many useful traits including finer fiber fineness, drought tolerance, and Fusarium and Verticillium resistance. We constructed the first bacterial artificial chromosome library for Gossypium tomentosum. With high quality and broad coverage, this library includes 200,832 clones, with an average insert size of about 122 kb and fewer than 3% empty clones. Our library is approximately 10-fold the size of the (AD)5-genome (2400 Mb) and provides a 99.7% probability of isolating genes of interest or their sequences. Seven of eight simple sequence repeats markers that are located on five different chromosomes and linked with resistance to Verticillium wilt could amplify the 50 superpools and obtained one to five hits. This high capacity library will be an important genomic resource for classifying and analyzing the evolution of allotetraploid cotton species as well as for isolating disease-resistance and drought-tolerance genes.

Simple sequence repeat techniques were used to identify the genetic diversity of 101 Gossypium arboreum accessions collected from India, Vietnam, and the southwest of China (Guizhou, Guangxi, and Yunnan provinces). Twenty-six pairs of SSR primers produced a total of 103 polymorphic loci with an average of 3.96 polymorphic loci per primer. The average of the effective number of alleles, Nei's gene diversity, and Shannon's information index were 0.59, 0.2835, and 0.4361, respectively. The diversity varied among different geographic regions. The result of principal component analysis was consistent with that of unweighted pair group method with arithmetic mean clustering analysis. The 101 G. arboreum accessions were clustered into 2 groups.

This study characterized CXC chemokine receptor 4 (CXCR4) expression in patients with mitral valve disease and chronic atrial fibrillation (AF). Forty-eight patients with chronic AF formed two groups based on whether they were treated with or without renin–angiotensin system (RAS) blockers (AF + RAS group; n = 25, or AF – RAS group; n = 23). The controls comprised 17 mitral valve disease patients with sinus rhythm (SR group). CXCR4 mRNA and protein levels in the left atria were significantly higher in the AF – RAS and AF + RAS groups than in the SR group. CXCR4 expression was significantly lower in the AF + RAS group than the AF – RAS group. More CD34+ cells expressed CXCR4 in the AF – RAS and AF + RAS groups than in the SR group. Angiotensin II, collagen I and left atrial diameter significantly positively correlated with CXCR4 expression in the AF – RAS group. These results suggest that CXCR4 expression is up-regulated in chronic AF patients with mitral valve disease, is associated with atrial remodelling, and that these effects are attenuated by RAS blockers.

Nutrient availability may control muscle growth directly and indirectly through its influence on regulatory factors. We analyzed the effects of nutrient availability on the breast muscle insulin-like growth factor system. Real time RT-PCR was used to quantify the level of transcription in breast muscle from Langshan (LS) layer and Arbor Acres (AA) broiler chickens subjected to different feeding regimens during embryonic and postnatal development. The AA chickens were fed AA diet (AA, control group) while the LS chickens were either fed LS diet (LL) or AA diet (LA). According to our results, insulin-like growth factor (IGF)-II (embryonic day 16 (E16) - postnatal day 42 (P42)), IGF-I receptor (IGF-IR, E18-P42), and IGF binding protein (IGFBP)-2 (E18-P42), -5 (E16-P14), -7 (E12-P0), and -3 (E12-P0) were positively correlated with IGF-I, while IGFBP-3 (P0-P28) was negatively correlated with IGF-I. In comparison, IGF-IR (E18-P42), IGFBP-2 (E18-P42), IGFBP-5 (E14-P0), and IGFBP-3 (E16-P0) were positively correlated with IGF-II, while IGF-IR (E10-E16) and IGFBP-3 (P0-P28) were negatively correlated with IGF-II. Moreover, IGFBP-2 (E16-P42), -7 (E10-E16), and -3 (E10-E16) were positively correlated with IGF-IR, while IGFBP-3 (P0-P28) was negatively correlated with IGF-IR. Finally, IGFBP-7 (E12-P0) was positively correlated with IGFBP-3, while IGFBP-2 (P0-P28) and -7 (P0-P42) were negatively correlated with IGFBP-3. Overall, the AA chickens exhibited higher levels of IGF-I, IGF-IR, and IGFBP-2 mRNA expression than the LL chickens, while the opposite was true for IGFBP-7. No strain differences in IGF-I, IGF-IR, and IGFBP-7 mRNA expression were detected between LA and AA chickens; however, a strain difference was observed for IGFBP-2. LA chickens exhibited higher levels of IGFBP-2 than LL chickens, while the opposite was true for IGFBP-7. Our data show the first evidence that certain genes may be correlated during specific developmental periods and that strain differences in the expression of those genes in LS and AA chickens are due to differential responses to the same diet.

Experimental data suggest that transplantation of EPCs attenuates monocrotaline-induced pulmonary hypertension in rats and dogs. In addition, our previous studies suggested that autologous EPC transplantation was feasible, safe, and might have beneficial effects on exercise capacity and pulmonary hemodynamics in adults with IPAH. Thus, we hypothesized that transplantation of EPCs would improve exercise capacity and pulmonary hemodynamics in children with IPAH. Thirteen children with IPAH received intravenous infusion of autologous EPCs. The right-sided heart catheterization and 6-MWD test were performed at baseline and at the time of 12 wk after cell infusion. At the time of 12 wk, mPAP decreased by 6.4 mmHg from 70.3 +/- 19.0 to 63.9 +/- 19.3 mmHg (p = 0.015). PVR decreased by approximately 19% from 1118 +/- 537 to 906 +/- 377 dyn s/cm(5) (p = 0.047). CO increased from 3.39 +/- 0.79 to 3.85 +/- 0.42 L/min (p = 0.048). The 6-MWD increased by 39 m from 359 +/- 82 to 399 +/- 74 m (p = 0.012). NYHA functional class also improved. There were no severe adverse events with cell infusion. The small pilot study suggested that intravenous infusion of autologous EPCs was feasible, safe, and associated with significant improvements in exercise capacity, NYHA functional class, and pulmonary hemodynamics in children with IPAH. Confirmation of these results in a randomized controlled trial are essential.

An orthogonal least squares technique for basis hunting (OLS-BH) is proposed to construct sparse radial basis function (RBF) models for NARX-type nonlinear systems. Unlike most of the existing RBF or kernel modelling methods, which places the RBF or kernel centers at the training input data points and use a fixed common variance for all the regressors, the proposed OLS-BH technique tunes the RBF center and diagonal covariance matrix of individual regressor by minimizing the training mean square error. An efficient optimization method is adopted for this basis hunting to select regressors in an orthogonal forward selection procedure. Experimental results obtained using this OLS-BH technique demonstrate that it offers a state-of-the-art method for constructing parsimonious RBF models with excellent generalization performance.