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We prove that the existence spectrum of Mendelsohn triple systems whose associated quasigroups satisfy distributivity corresponds to the Loeschian numbers, and provide some enumeration results. We do this by considering a description of the quasigroups in terms of commutative Moufang loops. In addition we provide constructions of Mendelsohn quasigroups that fail distributivity for asmany combinations of elements as possible. These systems are analogues of Hall triple systems and anti-mitre Steiner triple systems respectively.
Infant formulas lack the complex mixture of oligosaccharides found in human milk. These human milk oligosaccharides (HMO) may be pivotal to the development of the neonatal immune system. Few comprehensive analyses of the effects of HMO on immune cells from neonates have been undertaken. Herein, the direct effects of HMO on immune cells were analysed ex vivo. Peripheral blood mononuclear cells (PBMC) isolated from 10-d-old sow-reared (SR) or colostrum-deprived formula-fed (FF) pigs were stimulated for 72 h with single HMO, mixtures of single HMO or a complex mixture of HMO isolated from human milk (iHMO). T-cell phenotype, cytokine production and proliferation were measured by flow cytometry, immunoassay and [3H]thymidine incorporation, respectively. Stimulation with HMO had direct effects on PBMC. For instance, cells stimulated with iHMO produced more IL-10 than unstimulated cells, and cells stimulated with fucosylated HMO tended to proliferate less than unstimulated cells. Additionally, co-stimulation with HMO mixtures or single HMO altered PBMC responses to phytohaemagglutinin (PHA) or lipopolysaccharide (LPS) stimulation. Compared with PBMC stimulated with PHA alone, cells co-stimulated with iHMO and PHA proliferated more and had fewer detectable CD4+CD8+ T cells. Compared with PBMC stimulated by LPS alone, cells co-stimulated with a mixture of sialylated HMO and LPS proliferated more and tended to have fewer detectable CD4+ T cells. Differences in the baseline responses of PBMC isolated from the SR or FF pigs were observed. In summary, HMO directly affected PBMC populations and functions. Additionally, ex vivo measurements of PBMC phenotype, cytokine production and proliferation were influenced by the neonate's diet.
Antibiotics are one of the most important medical discoveries of the 20th century and will remain an essential tool for treating animal and human diseases in the 21st century. However, antibiotic resistance among bacterial pathogens and concerns over their extensive use in food animals has garnered global interest in limiting antibiotic use in animal agriculture. Yet, limiting the availability of medical interventions to prevent and control animal diseases on the farm will directly impact global food security and safety as well as animal and human health. Insufficient attention has been given to the scientific breakthroughs and novel technologies that provide alternatives to antibiotics. The objectives of the symposium ‘Alternatives to Antibiotics’ were to highlight promising research results and novel technologies that could potentially lead to alternatives to conventional antibiotics, and assess challenges associated with their commercialization, and provide actionable strategies to support development of alternative antimicrobials. The symposium focused on the latest scientific breakthroughs and technologies that could provide new options and alternative strategies for preventing and treating diseases of animals. Some of these new technologies have direct applications as medical interventions for human health, but the focus of the symposium was animal production, animal health and food safety during food-animal production. Five subject areas were explored in detail through scientific presentations and expert panel discussions, including: (1) alternatives to antibiotics, lessons from nature; (2) immune modulation approaches to enhance disease resistance and to treat animal diseases; (3) gut microbiome and immune development, health and diseases; (4) alternatives to antibiotics for animal production; and (5) regulatory pathways to enable the licensure of alternatives to antibiotics.
Human milk (HM) is rich in oligosaccharides (HMO) that exert prebiotic and anti-infective activities. HM feeding reduces the incidence of rotavirus (RV) infection in infants. Herein, the anti-RV activity of oligosaccharides was tested in an established in vitro system for assessing cellular binding and viral infectivity/replication, and also tested in a newly developed, acute RV infection, in situ piglet model. For the in vitro work, crude HMO isolated from pooled HM, neutral HMO (lacto-N-neotetraose, LNnT; 2′-fucosyllactose) and acidic HMO (aHMO, 3′-sialyllactose, 3′-SL; 6′-sialyllactose, 6′-SL) were tested against the porcine OSU strain and human RV Wa strain. The RV Wa strain was not inhibited by any oligosaccharides. However, the RV OSU strain infectivity was dose-dependently inhibited by sialic acid (SA)-containing HMO. 3′-SL and 6′-SL concordantly inhibited 125I-radiolabelled RV cellular binding and infectivity/replication. For the in situ study, a midline laparotomy was performed on 21-d-old formula-fed piglets and six 10 cm loops of ileum were isolated in situ. Briefly, 2 mg/ml of LNnT, aHMO mixture (40 % 6′-SL/10 % 3′-SL/50 % SA) or media with or without the RV OSU strain (1 × 107 focus-forming units) were injected into the loops and maintained for 6 h. The loops treated with HMO treatments+RV had lower RV replication, as assessed by non-structural protein-4 (NSP4) mRNA expression, than RV-treated loops alone. In conclusion, SA-containing HMO inhibited RV infectivity in vitro; however, both neutral HMO and SA with aHMO decreased NSP4 replication during acute RV infection in situ.
We report production of a self-injected, collimated (8 mrad divergence), 600 pC bunch of electrons with energies up to 350 MeV from a petawatt laser-driven plasma accelerator in a plasma of electron density ne = 1017 cm−3, an order of magnitude lower than previous self-injected laser-plasma accelerators. The energy of the focused drive laser pulse (150 J, 150 fs) was distributed over several hot spots. Simulations show that these hot spots remained independent over a 5 cm interaction length, and produced weakly nonlinear plasma wakes without bubble formation capable of accelerating pre-heated (~1 MeV) plasma electrons up to the observed energies. The required pre-heating is attributed tentatively to pre-pulse interactions with the plasma.
Copper-carbon alloy films containing between 7 and 40 at.% carbon, as measured with 6.2 MeV He++ scattering, were deposited by ion beam assisted deposition (IBAD) on pure epitaxial Cu(100) films on Si(100) substrates. The IBAD process involved simultaneous deposition of evaporated copper (0.3 to 2.0 nm/s) and bombardment with 400 eV ions (340 μA/cm2 on target) from a Kaufman ion source fed with methane. Transmission electron microscopy (TEM) showed that an IBAD layer with 15 at.%C was epitaxial with the underlying pure Cu(100) layer. X-ray diffraction (XRD) indicated that the IBAD films were epitaxial at low carbon concentration but polycrystalline at high concentration. The small range of carbon ions in copper and the evidence of sputtering suggest that this loss of epitaxy resulted from increased surface carbon interfering with epitaxy. Although carbon and copper are immiscible, TEM and XRD have revealed no evidence of carbon precipitation, indicating that the carbon may be in solution and that such IBAD layers may be suitable for diamond formation by laser annealing.
Transparent, insulating ZnO thin films have been deposited in-situ by pulsed laser deposition (PLD) from sintered targets. Films were deposited on substrates of fused quartz, <0001> A12O3, polycrystalline and textured (111) Au, at several substrate deposition temperatures (TSubstrate ≤ 700° C) and background oxygen pressures (P ≤ 300 mTorr). Film structure, morphology and electrical properties were characterized by X-ray diffraction, Rutherford backscattering spectrometry, optical properties were characterized by infrared transmission and reflection, and electrical resistivity was measured normal to the films. Films were crystalline, phase pure, and c-axis oriented. ZnO films deposited onto fused quartz and <0001> sapphire showed x-ray rocking curve full width at half maxima of 5° and 0.34°, respectively. The structure of ZnO films deposited on (111) textured Au was sensitive to the degree of texturing in the Au. The resistivity of PLD ZnO films was 61-63 kΩcm which was a factor of three improvement over sputter deposited films. Deposition of Au by both PLD and IBAD showed a negative correlation between the crystalline texturing and film adherence.
The atomic origins of the intrinsic mechanical and thermal properties of the interfaces between niobium and its carbides and silicides are explored using both the layer Korringa-Kohn-Rostoker (LKKR) technique and model cluster calculations. The relative stability of an idealised  interface is predicted from charge transfer arguments.
Damage introduction in III-V nitrides during dry etching can be simulated by exposingthe samples to pure Ar plasmas for study of the physical (ion-bombardment) effects.Changes in conductivity of InN, In0.5Ga 0.5N and In0.5Al0.5N layers exposed to Ar plasmasunder both Electron Cyclotron Resonance and reactive ion etching conditions have beenmeasured as a function of rfpower, pressure and exposure time. The combination of highmicrowave and high rf powers produces large increases (10-_104 times) in sheet resistanceof the nitrides, but conditions more typical of real etching processes (rf power < 150W) donot change the bulk electrical properties. The nitrides are more resistant to damageintroduction than other III-V semiconductors. The removal of damage-related trapsoccurs with an activation energy of ∼2.7eV. High ion currents during ECR etching canproduce substantial conductivity changes, whereas the lower currents under RIEconditions do not affect the nitrides. It is difficult to avoid preferential loss of N in thenear-surface of these materials, which leads to leakage currents in rectifying metal contactsdeposited on these surfaces.
Thin films (∼1000 Å) of LaxCa1−xMnOδ (x=0.67) were deposited onto LaA1O3 (100) substrates at of 600 and 700°C. Varying the oxygen deposition pressure between 15 and 400 mTorr systematically changed the oxygen concentrations in the as deposited films. Asdeposited films exhibited an orthorhombic structure with an oxygen pressure dependent lattice parameter. The films were highly oriented as characterized by narrow x-ray ω-scans (FWHM ≤ 0.16 −0.70°). At low pressures, the films were preferentially (202) oriented while at high pressures deposited films had a (040) preferred orientation. A 900°C anneal in flowing oxygen for a film deposited at low oxygen pressures resulted in a decrease in the lattice parameter (associated with an increase in δ) and a change in the preferred orientation from (202) to (040). The resistivity as a function of temperature (R(T)) showed a significant variation as a function of growth conditions. At 600°C, the peak in the resistivity curve (Tm) varied between 73 and 93 K for P(O2) = 15 to 400 mTorr, while at 700°C, Tm was ∼150 K. For films deposited at 600°C, the resistivity was reduced by a factor of 103 for H = 9T and Tm was shifted to 150 K. The activation energy associated with the semiconducting phase was approximately the same for all as-deposited films (∼100 meV).
Thick films (0.6 and 2.0 μm) of the colossal magnetoresistance (CMR) material, La0.7Ca0.3MnO3 (LCMO), have been grown by pulsed laser deposition (PLD). The films were grown from single-phase LCMO targets in 100 mTorr 02 pressures and the material deposited on (100) LaAlO3 substrates at deposition temperatures of 800°C. The deposited films were characterized by X-ray diffraction (XRD), magnetic field-dependent resistivity, and Rutherford backscattering spectroscopy (RBS). The LCMO films were shown by XRD to adopt an orthorhombic structure. Brief post-deposition annealing led to ~50,000% and ~12,000% MR effect in the 0.6 μm and 2.0 μm films, respectively.
Reproducible fabrication of high performance metal oxide semiconductor field effect transistors (MOSFETs) from compound semiconductors will require both good interfacial electrical characteristics and good thermal stability. While dielectrics such as SiO2, AIN, and GdGaOx have demonstrated low to moderate interface state densities, questions remain about their thermal stability and reliability, particularly for use in high power or high temperature widebandgap devices. In this paper we will compare the utility of two potential gate dielectric materials: GdOx and GaOx. GdOx has been found to produce layers with excellent surface morphologies as evidenced by surface roughness of less than I nm. Stoichiometric films can be easily obtained over a range of deposition conditions, though deposition temperatures of 500°C appear to offer the optimum interfacial electrical quality. By contrast GaOx films are quite rough, polycrystalline and show poor thermal stability. Further they exhibit a range of stoichiometries depending upon deposition temperature, Ga flux and oxygen flux. This paper will describe the relationship between deposition conditions and film characteristics for both materials, and will present electrical characterization of capacitors fabricated from GdOx on Si.
Anisotropic pattern transfer has been performed for GaN, InN and AIN in Cl2/Ar, BI3/Ar and BBr3/Ar Inductively Coupled Plasmas(ICP). Controlled etch rates in the range of 500–1500Å·min−1 are obtained for III-nitride materials in Cl2/Ar chemistry. Etch selectivities of 100:1 were achieved for InN over both GaN and AIN in the BI3 mixtures, while for BBr3 discharges values of 100:1 for InN over AIN and 25:1 for InN over GaN were measured.
InN has been grown in a gas-source MBE system using an RF nitrogen plasma source and standard TMI, solution TMI and solid In. Both solid and solution TMI produce InN with electron and carbon concentrations ≥ 1020 cm−3. Solution TMI-derived material, however, contains significantly less oxygen (8 × 1018 cm−3 vs. ≥ 1020 cm−3 for solid TMI). While the amine used to liquefy the TMI helps to displace the ether believed to be responsible for the oxygen contamination, it also appears to interfere with the growth, resulting in poorer morphology than for standard TMI. While solid In produced the lowest carrier concentration (≤ mid-1018 cm−3), it also produced the worst morphology of the sources examined, presumably due to poor surface mobility. Based on this data, it appears that carbon can play a significant role in the electrical properties of InN, and that the In source is critical in determining the structural quality.
Etch rates up to 7,000Å/min. for GaN are obtained in Cl2/H2/Ar or BCl3/Ar ECR discharges at 1–3mTorr and moderate dc biases. Typical rates with HI/H2 are about a factor of three lower under the same conditions, while CH4/H2 produces maximum rates of only ˜2000Å/min. The role of additives such as SF6, N2, H2 or Ar to the basic chlorine, bromine, iodine or methane-hydrogen plasma chemistries are discussed. Their effect can be either chemical ( in forming volatile products with N) or physical ( in breaking bonds or enhancing desorption of the etch products). The nitrides differ from conventional III-V's in that bondbreaking to allow formation of the etch products is a critical factor. Threshold ion energies for the onset of etching of GaN, InGaN and InAlN are ≥75eV.
In order to maximize the performance of III-Nitride devices, it is necessary to develop thermally stable low resistance Ohmic contacts to III-N based electronic structures. This paper reports on the utility of InN as an aid to contact formation on widegap materials such as InAIN. For n-type materials, several questions relating to the growth conditions have been explored. Specifically, the impact of substrate type (GaAs vs. Sapphire), cap layer growth temperature and V/III ratio on contact resistance has been investigated. It was found that the use of sapphire substrates combined with high growth temperatures (575°C) and high V/III ratios produced acceptable contact resistances (∼10−6Ohm-cm2) to InAIN.
High-density plasma etching has been an effective patterning technique for the group-III nitrides due to ion fluxes which are 2 to 4 orders of magnitude higher than more conventional reactive ion etch (RIE) systems. GaN etch rates exceeding 0.68 μm/min have been reported in Cl2/H2/Ar inductively coupled plasmas (ICP) at -280 V dc-bias. Under these conditions, the etch mechanism is dominated by ion bombardment energies which can induce damage and minimize etch selectivity. High selectivity etch processes are often necessary for heterostructure devices which are becoming more prominent as growth techniques improve. In this study, we will report high-density ICP etch rates and selectivities for GaN, AIN, and InN as a function of cathode power, ICP-source power, and chamber pressure. GaN:AIN selectivities > 8:1 were observed in a Cl2/Ar plasma at 10 mTorr pressure, 500 W ICP-source power, and 130 W cathode rf-power, while the GaN:InN selectivity was optimized at ∼ 6.5:1 at 5 mTorr, 500 W ICP-source power, and 130 W cathode rf-power.
Auger electron spectroscopy was used to examine the nitridation behavior of GaAs, sapphire and lithium aluminate (LAO) substrates exposed to an RF nitrogen plasma. No evidence of nitridation was found for the sapphire and LAO substrates. GaAs substrates did show evidence of nitridation which led to smooth InN surface morphology without the need for a low temperature buffer. Comparable InN films were obtained on sapphire and LAO substrates when a low temperature AlN buffer was used. Hall measurements indicate background carrier concentrations are relatively insensitive to substrate type, though mobilities decreased as surface morphology was improved.