Near-Monochromatic Tuneable Cryogenic Niobium Electron Field Emitter

Creating, manipulating, and detecting coherent electrons is at the heart of future quantum microscopy and spectroscopy technologies. Leveraging and specifically altering the quantum features of an electron beam source at low temperatures can enhance its emission properties. Here, we describe electron field emission from a monocrystalline, superconducting niobium nanotip at a temperature of 5.9 K. The emitted electron energy spectrum reveals an ultranarrow distribution down to 16 meV due to tunable resonant tunneling field emission via localized band states at a nanoprotrusion's apex and a cutoff at the sharp low-temperature Fermi edge. This is an order of magnitude lower than for conventional field emission electron sources. The self-focusing geometry of the tip leads to emission in an angle of 3.7°, a reduced brightness of 3.8×10^{8}  A/(m^{2} sr V), and a stability of hours at 4.1 nA beam current and 69 meV energy width. This source will decrease the impact of lens aberration and enable new modes in low-energy electron microscopy, electron energy loss spectroscopy, and high-resolution vibrational spectroscopy.

Pharmacokinetics of tildipirosin in porcine plasma, lung tissue, and bronchial fluid and effects of test conditions on in vitro activity against reference strains and field isolates of Actinobacillus pleuropneumoniae

The pharmacokinetics of tildipirosin (Zuprevo(®) 40 mg/mL solution for injection for pigs), a novel 16-membered-ring macrolide for the treatment for swine respiratory disease (SRD), was investigated in studies collecting blood plasma and postmortem samples of lung tissue and bronchial fluid (BF) from swine. In view of factors influencing the in vitro activity of macrolides, and for the interpretation of tildipirosin pharmacokinetics in relation to minimum inhibitory concentrations (MIC), additional experiments were conducted to study the effects of pH, carbon dioxide-enriched atmosphere, buffers, and serum on tildipirosin MICs for various reference strains and Actinobacillus (A.) pleuropneumoniae field isolates. After single intramuscular (i.m.) injection at 4 mg/kg body weight, maximum plasma concentration (Cmax) was 0.9 μg/mL observed within 23 min (Tmax ). Mean residence time from the time of dosing to the time of last measurable concentration (MRTlast) and terminal half-life (T1/2) both were about 4 days. A dose-response relationship with no significant sex effect is observed for area under the plasma concentration-time curve from time 0 to the last sampling time with a quantifiable drug concentration (AUClast) over the range of doses up to 6 mg/kg. However, linear dose proportionality could not be proven with statistical methods. The time-concentration profile of tildipirosin in BF and lung far exceeded that in blood plasma. In lung, tildipirosin concentrations reached 3.1 μg/g at 2 h, peaked at 4.3 μg/g at day 1, and slowly declined to 0.8 μg/g at day 17. In BF, tildipirosin levels were 14.3, 7.0, and 6.5 μg/g at days 5, 10, and 14. T1/2 in lung was ∼7 days. Tildipirosin is rapidly and extensively distributed to the respiratory tract followed by slow elimination. Culture media pH and carbon dioxide-enriched atmosphere (CO2 -EA) had a marked impact on in vitro activity of tildipirosin in reference strains of various rapidly growing aerobic and fastidious bacteria including Histophilus (H.) somni ATCC 700025 and A. pleuropneumoniae ATCC 27090. For A. pleuropneumoniae ATCC 27090 testing conditions without CO2 -EA resulted in reduced acidification of culture media pH and a reduction in the minimum inhibitory concentrations compared to standard in vitro test conditions by 2 log2 dilution steps (4-fold) from 8 to 2 μg/mL. Supplementary buffering of standard culture media resulted in a reduction in the A. pleuropneumoniae (n = 8) MIC range by 4 log2 dilution steps (16-fold) from 8-16 to 0.5-1 μg/mL. Incremental supplementation of culture media with 50% serum resulted in noticeable shifts to lower minimum or maximum MICs by at least 2 log2 dilution steps (≥4-fold) in all aerobic and fastidious reference strains tested except for Pasteurella (P.) multocida. The MIC of A. pleuropneumoniae ATCC 27090 decreased by 2-4 log2 dilution steps (4 to 16-fold) from 8 to 0.5-2 μg/mL when 50% serum was added to the standard assay. Considering a higher presence of serum and the rather neutral pH conditions maintained in vivo, it is suggested to take the influence of these factors on in vitro activity into account when interpreting tildipirosin MICs for A. pleuropneumoniae in relation to pharmacokinetics.

Effects of somatotropin treatment on growth performance, carcass traits, and the endocrine system in finishing beef heifers

The objectives of this study were to investigate the effects of exogenous somatotropin on growth performance and carcass traits and on concentrations of somatotropin (ST), IGF-I, insulin, glucagon, free fatty acids (FFA), and glucose in plasma of finishing Simmental beef heifers. Three treatment groups, which included 12 heifers each, received a subcutaneous injection of a slowly released recombinant bovine somatotropin (rbST) at two doses (320 and 640 mg, respectively) or a placebo at 2-wk intervals. Treatments began at an average BW of 286 kg and continued until the animals were slaughtered at approximately 520 kg. Heifers had ad libitum access to corn silage and received 1.8 kg/d of concentrate. A before-feeding blood sample was collected from the jugular vein immediately before and 1 wk after each injection during treatment. Treatment tended to increase ADG and to reduce energy consumption per kilogram of gain, whereas feed and energy intake were not altered. Dressing percentage and conformation did not seem to be affected by treatment. Treatment led to a dose-dependent reduction of fat tissue in carcass as well as in kidney fat and to a simultaneous increase of lean tissue (P < .05). Furthermore, treatment caused moderate increases of ST in both treated groups, whereas IGF-I concentrations increased markedly soon after the beginning of the treatment. Insulin and FFA concentrations were elevated in treated groups compared with controls. Glucagon concentrations were not altered by treatment. Effects on growth performance and carcass characteristics are discussed in view of metabolic and endocrine changes.

Localization and concentration of a new bioactive acetic seminal fluid protein (aSFP) in bulls (Bos taurus)

The concentration of the new bioactive acetic seminal fluid protein (aSFP) was determined in body fluids of bulls. An aSFP-specific radioimmunoassay was elaborated and established for routine measurement. No crossreaction of the aSFP antibody was found with other seminal plasma proteins and known growth factors. The 14 kDa aSFP was detected in secretions of ampulla and seminal vesicles by immunoblot analysis, but not in testis, epididymis or blood. Large quantities of aSFP were measured by radioimmunoassay in the fluid from the ampulla (2.6 +/- 0.3 mg ml-1) and seminal vesicles (3.0 +/- 0.4 mg ml-1). Immunohistochemistry techniques demonstrated that aSFP was localized mainly in the secretory epithelium of ampulla and seminal vesicles. Large amounts of aSFP (4.0 +/- 0.4 mg ml-1) were present in seminal plasma of bulls within a range of 1-7 mg ml-1, but aSFP could not be found on membranes of spermatozoa. Concentrations vary considerably among individuals, suggesting that aSFP may have a role in bovine reproduction.