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Knowledge of the effects of burial depth and burial duration on seed viability and, consequently, seedbank persistence of Palmer amaranth (Amaranthus palmeri S. Watson) and waterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer] ecotypes can be used for the development of efficient weed management programs. This is of particular interest, given the great fecundity of both species and, consequently, their high seedbank replenishment potential. Seeds of both species collected from five different locations across the United States were investigated in seven states (sites) with different soil and climatic conditions. Seeds were placed at two depths (0 and 15 cm) for 3 yr. Each year, seeds were retrieved, and seed damage (shrunken, malformed, or broken) plus losses (deteriorated and futile germination) and viability were evaluated. Greater seed damage plus loss averaged across seed origin, burial depth, and year was recorded for lots tested at Illinois (51.3% and 51.8%) followed by Tennessee (40.5% and 45.1%) and Missouri (39.2% and 42%) for A. palmeri and A. tuberculatus, respectively. The site differences for seed persistence were probably due to higher volumetric water content at these sites. Rates of seed demise were directly proportional to burial depth (α=0.001), whereas the percentage of viable seeds recovered after 36 mo on the soil surface ranged from 4.1% to 4.3% compared with 5% to 5.3% at the 15-cm depth for A. palmeri and A. tuberculatus, respectively. Seed viability loss was greater in the seeds placed on the soil surface compared with the buried seeds. The greatest influences on seed viability were burial conditions and time and site-specific soil conditions, more so than geographical location. Thus, management of these weed species should focus on reducing seed shattering, enhancing seed removal from the soil surface, or adjusting tillage systems.
Despite improvements in the medical and surgical management of infants with CHD, growth failure before surgery in many infants continues to be a significant concern. A nutritional pathway was developed, the aim of which was to provide a structured approach to nutritional care for infants with CHD awaiting surgery.
Materials and methods
The modified Delphi process was development of a nutritional pathway; initial stakeholder meeting to finalise draft guidelines and develop questions; round 1 anonymous online survey; round 2 online survey; regional cardiac conference and pathway revision; and final expert meeting and pathway finalisation.
Paediatric Dietitians from all 11 of the paediatric cardiology surgical centres in the United Kingdom contributed to the guideline development. In all, 33% of participants had 9 or more years of experience working with infants with CHD. By the end of rounds 1 and 2, 76 and 96% of participants, respectively, were in agreement with the statements. Three statements where consensus was not achieved by the end of round 2 were discussed and agreed at the final expert group meeting.
Nutrition guidelines were developed for infants with CHD awaiting surgery, using a modified Delphi process, incorporating the best available evidence and expert opinion with regard to nutritional support in this group.
Maternal diet-induced obesity can cause detrimental developmental origins of health and disease in offspring. Perinatal exposure to a high-fat diet (HFD) can lead to later behavioral and metabolic disturbances, but it is not clear which behaviors and metabolic parameters are most vulnerable. To address this critical gap, biparental and monogamous oldfield mice (Peromyscus polionotus), which may better replicate most human societies, were used in the current study. About 2 weeks before breeding, adult females were placed on a control or HFD and maintained on the diets throughout gestation and lactation. F1 offspring were placed at weaning (30 days of age) on the control diet and spatial learning and memory, anxiety, exploratory, voluntary physical activity, and metabolic parameters were tested when they reached adulthood (90 days of age). Surprisingly, maternal HFD caused decreased latency in initial and reverse Barnes maze trials in male, but not female, offspring. Both male and female HFD-fed offspring showed increased anxiogenic behaviors, but decreased exploratory and voluntary physical activity. Moreover, HFD offspring demonstrated lower resting energy expenditure (EE) compared with controls. Accordingly, HFD offspring weighed more at adulthood than those from control fed dams, likely the result of reduced physical activity and EE. Current findings indicate a maternal HFD may increase obesity susceptibility in offspring due to prenatal programming resulting in reduced physical activity and EE later in life. Further work is needed to determine the underpinning neural and metabolic mechanisms by which a maternal HFD adversely affects neurobehavioral and metabolic pathways in offspring.
Early patterns of gut colonization may predispose children to adult disease. Exposures in utero and during delivery are associated with the infant gut microbiome. Although ~35% of women carry group B strep (GBS; Streptococcus agalactiae) during pregnancy, it is unknown if GBS presence influences the infant gut microbiome. As part of a population-based, general risk birth cohort, stool specimens were collected from infant’s diapers at research visits conducted at ~1 and 6 months of age. Using the Illumina MiSeq (San Diego, CA) platform, the V4 region of the bacterial 16S rRNA gene was sequenced. Infant gut bacterial community compositional differences by maternal GBS status were evaluated using permutational multivariate analysis of variance. Individual operational taxonomic units (OTUs) were tested using a zero-inflated negative binomial model. Data on maternal GBS and infant gut microbiota from either 1 (n=112) or 6-month-old stool (n=150) specimens was available on 262 maternal-child pairs. Eighty women (30.5%) were GBS+, of who 58 (72.5%) were given intrapartum antibiotics. After adjusting for maternal race, prenatal antifungal use and intrapartum antibiotics, maternal GBS status was statistically significantly associated with gut bacterial composition in the 6 month visit specimen (Canberra R2=0.008, P=0.008; Unweighted UniFrac R2=0.010, P=0.011). Individual OTU tests revealed that infants of GBS+ mothers were significantly enriched for specific members of the Clostridiaceae, Ruminococcoceae, and Enterococcaceae in the 6 month specimens compared with infants of GBS- mothers. Whether these taxonomic differences in infant gut microbiota at 6 months lead to differential predisposition for adult disease requires additional study.
We present a novel ZnO:Al fabrication process consisting of room-temperature vacuum sputtering followed by an excimer laser annealing (ELA). The ELA treatment improves the optical transmission of the films, and the film resistivities (<1 mΩ·cm) remain stable or improve with increasing laser fluence up to 0.6 J/cm2, as the carrier density increases but the carrier mobility is degraded. This process is followed by a standard dilute HCl chemical texturing step, and produces substrates with suitable texture, conductivity, and transparency properties for thinfilm photovoltaic applications. Substrates resulting from this process display elevated haze levels (80% at 600 nm and 50% at 800 nm) after the wet-chemical etching step. Such substrates have been used to make single junction hydrogenated nanocrystalline silicon solar cells, and an increase in the short-circuit current of up to 2.2 mA/cm2 is observed compared to a substrate deposited by a standard room-temperature sputtering + wet-etch process. This gain is primarily due to increased photo-response in the red due to improved light-scattering, as at wavelengths greater than 600 nm, a gain in photocurrent of up to 1.7 mA/cm2 is observed.
Over the last three decades Computational Fluid Dynamics (CFD) has gradually joined the
wind tunnel and flight test as a primary flow analysis tool for aerodynamic designers. CFD
has had its most favorable impact on the aerodynamic design of the high-speed cruise
configuration of a transport. This success has raised expectations among aerodynamicists
that the applicability of CFD can be extended to the full flight envelope. However, the
complex nature of the flows and geometries involved places substantially increased demands
on the solution methodology and resources required. Currently most simulations involve
Reynolds-Averaged Navier-Stokes (RANS) codes although Large Eddy Simulation (LES) and
Detached Eddy Suimulation (DES) codes are occasionally used for component analysis or
theoretical studies. Despite simplified underlying assumptions, current RANS turbulence
models have been spectacularly successful for analyzing attached, transonic flows. Whether
or not these same models are applicable to complex flows with smooth surface separation is
an open question. A prerequisite for answering this question is absolute confidence that
the CFD codes employed reliably solve the continuous equations involved. Too often,
failure to agree with experiment is mistakenly ascribed to the turbulence model rather
than inadequate numerics. Grid convergence in three dimensions is rarely achieved. Even
residual convergence on a given grid is often inadequate. This paper discusses issues
involved in residual and especially grid convergence.
High-quality crystalline Si1-xGex (x=0.10 and 0.25)
alloys were implanted with 70 keV Er+ ions at temperatures of
350°C and 550°C to a fluence of 1015 cm−2. In-situ
Rutherford backscattering/channeling (RBS) analysis supplemented with
transmission electron microscopy (TEM) showed that as-implanted alloys were
in form of ternary solid solutions with a peak Er concentration of 1 at.%
without any trace of Er-Si or Er-Ge precipitation.
In the samples implanted at 350°C Er atoms were found to be distributed
randomly in the amorphous host matrix. Post-implantation annealing at
different temperatures up to 600° showed that the solid phase epitaxial
regrowth of the damaged layers strongly depends on both the Ge concentration
in the alloys and the temperature of annealing. Along with the
recrystallization of the damaged matrix, annealing was observed to induce
simultaneous removal of nearly all the implanted Er as the recrystallization
front progresses towards the surface.
In contrast, high temperature implantation at 550°C led to spontaneous
recovery of the alloy crystallinity and incorporation of considerable
fraction of implanted Er atoms on regular tetrahedral interstitial sites in
the host lattice.
The availability of high power high frequency microwave sources of up to tens of kW has opened up important technological and industrial applications of microwave radiation. The particular use of gyrotrons for generating the high power microwaves is considered.
The application of high power microwaves for fusing wear resistant coatings onto refractory materials is discussed, together with the brazing of ceramics, welding together of thick metal parts and the rapid heating and curing of polymers for high reliability long life environmental coatings.
It is shown that the use of high power gyrotron radiation enables considerable improvements to be made on conventional technologies for high temperature processing of materials and enables the development of new and efficient processes.
Systematic differences in pH, cation/proton ion activity ratios, and redox have been observed between solutions produced in rock-water hydrothermal experiments with tuff, granite, and basalt. Stable pH values in tuff-water experiments may be as much as 1.5 pH units more acidic than basalt-water experiments at the same temperature and ionic strength. Redox (log fO2) values in 300°C tuff experiments are 4–7 orders of magnitude more oxidizing than basalt experiments and ca. 4 log units more oxidizing than the magnetite-hematite buffer. Such fluid differences could significantly affect the performance of a high-level nuclear waste repository and should be considered in repository design and siting.
The self-consistent Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method is applied to determine the changes in the Cr electronic structure due to addition of up to 30% Ru. The results provide an interpretation of the coexisting antiferromagnetism and superconductivity in terms of specific pieces of Fermi surface. The strong nesting which occurs for the Cr Fermi surface survives the addition of at least 20% Ru, in agreement with the observed persistence of antiferromagnetism into this region.
We have investigated improving the crystalline quality of epitaxial silicon grown on SIMOX by confining threading dislocations in the original Si top layer using a GeSi strained layer. Epitaxial Si/GeSi/Si structures were grown by CVD on SIMOX and Si substrates with a GeSi alloy layer about 1000 − 1500 angstroms thick with Ge concentrations of about 0−20%. A Ge concentration in the alloy layer of about 5.5% or higher appears to be necessary in order to bend any of the threading dislocations from the original SIMOX top layer. For a higher Ge concentration of about 16%, most of the threading dislocations appear to be bent and confined by the GeSi layer. In addition, the GeSi strained layers grown by CVD (at about 1000°C) appear to be high quality and no misfit dislocations were observed in the regions studied by XTEM and plane view TEM.