Comparison of nitrogen-15 and diaminopimelic acid for estimating bacterial protein synthesis of lactating cows fed diets of varying protein degradability

Three lactating Holstein cows fitted with duodenal cannulae were fed diets containing cottonseed meal, corn gluten meal, or blood meal as protein supplements in a 3 c 3 Latin square experiment. Diets averaged 15% CP and were 60% concentrate, 31% corn silage, and 9% alfalfa hay. The flow marker was Cr2O3; the bacterial protein fraction of digesta CP was estimated by 15N (as ammonium sulfate) and diaminopimelic acid. The undegraded fraction of total feed protein entering the duodenum for respective diets was .52, .57, and .69. The 15N method was less variable than diaminopimelic acid. Based on 15N, percentage of bacterial of total protein differed among treatments (61.5, 59.4, and 55.0, respectively). Ten percent more protein entered the duodenum on blood meal than other diets, but differences were not significant. Protein sources were similar in microbial passage, but degraded protein was used most efficiently for microbial synthesis on blood meal. Incorporation of 15N consumed into bacterial protein ranged from 50 to 83% with numerically highest values on blood meal, suggesting greater efficiency of ammonia, capture. Recoveries of 15N for the 72 h as milk, feces and urine ranged from 54 to 78%.     

Size-exclusive nanosensor for quantitative analysis of fullerene C60

This paper presents the first development of a mass-sensitive nanosensor for the isolation and quantitative analyses of engineered fullerene (C??) nanoparticles, while excluding mixtures of structurally similar fullerenes. Amino-modified beta-cyclodextrin (β-CD-NH?) was synthesized and confirmed by 1HNMR as the host molecule to isolate the desired fullerene C??. This was subsequently assembled onto the surfaces of gold-coated quartz crystal microbalance (QCM) electrodes using N-dicyclohexylcarbodiimide/N-hydroxysuccinimide (DCC/NHS) surface immobilization chemistry to create a selective molecular configuration described as (Au)-S-(CH?)2-CONH-beta-CD sensor. The mass change on the sensor configuration on the QCM was monitored for selective quantitative analysis of fullerene C?? from a C??/C?? mixture and soil samples. About ~101?-101? C?? particles/cm2 were successfully quantified by QCM measurements. Continuous spike of 200 μL of 0.14 mg C?? /mL produced changes in frequency (-Δf) that varied exponentially with concentration. FESEM and time-of-flight secondary-ion mass spectrometry confirmed the validity of sensor surface chemistry before and after exposure to fullerene C??. The utility of this sensor for spiked real-world soil samples has been demonstrated. Comparable sensitivity was obtained using both the soil and purified toluene samples. This work demonstrates that the sensor has potential application in complex environmental matrices.     

Splanchnic and mammary nitrogen metabolism by dairy cows fed dry-rolled or steam-flaked sorghum grain

Objectives were to determine net release or uptake of alpha-amino N, ammonia N, and urea N across portal-drained viscera, liver, splanchnic, and mammary tissues of lactating Holstein cows (n = 8, 86 +/- 8 d in milk) fed alfalfa hay-based total mixed rations containing 40% dry-rolled or steam-flaked sorghum grain. The total mixed rations were offered at 12-h intervals in a crossover design. Blood samples were obtained from indwelling catheters in the portal, hepatic, and mammary veins and mesenteric or costoabdominal arteries, every 2 h for each cow and diet. Steam-flaking increased in vitro rate of starch hydrolysis compared with dry-rolled sorghum (66 vs. 25%). Diet did not alter dry matter intake (18.2 +/- 0.3 kg). Daily milk yield (27.6 +/- 0.8 kg), efficiency of production, and most milk components did not differ between diets, but fat yield was reduced (0.86 vs. 0.91 kg/d) by steam-flaked sorghum, and lactose concentration was increased (4.99 vs. 4.82%). Blood flows in portal and hepatic veins did not differ between diets. Steam-flaking tended to increase urea N cycling to the gut (162 vs. 95 g/d) compared with dry-rolling of sorghum, whereas net absorption of ammonia N and alpha-amino N across portal-drained viscera were decreased. Net mammary uptake of a-amino N increased more than 20% (83 vs. 67 g/d), resulting in a higher mammary extraction ratio (15 vs. 11%) for steam-flaked versus dry-rolled sorghum. Flaking of sorghum improved the efficiency of postabsorptive N metabolism by increasing urea N cycled to the gut and alpha-amino N uptake by the mammary gland.     

Climate changes,biofuels and the sustainable future

Climate change is one of the most dangerous problems of the contemporary world. We can either adapt to the corresponding changes or try to reduce their impact by significantly reducing fossil fuel burning. A hydrogen-based economy using energy from biomass, solar, wind and other renewable sources and/or nuclear energy seems to be a viable alternative. Here we analyse the possibilities of the biofuels to replace fossil fuels and their potential to contribute to hydrogen economy.     

Enzyme-modulated cleavage of dsDNA for supramolecular design of biosensors.

Supramolecular docking and immobilization of biotinylated dsDNA onto a self-assembled monolayer of avidin have been measured using impedance spectroscopy and quartz crystal microbalance technique. The formation of the serial assembly was first achieved by linearizing circular plasmid dsDNA using BamH I endonuclease enzyme. This was followed by a bisulfite-catalyzed transamination reaction in order to biotinylate the dsDNA. The reaction is single-strand specific, and it specifically targets unpaired cytosine bases generated during the enzyme cleavage. The biotinylated dsDNA was then used as a ligand at a gold electrode containing avidin. The process was monitored by ac impedance spectroscopy that was used to probe the changes in interfacial electron-transfer resistance upon binding and a microgravimetric quartz crystal microbalance that reflected in situ mass changes on the dsDNA-functionalized substrates. Our results demonstrated that this approach could be employed for the determination of small-molecular-weight organics such as cisplatin, daunomycin, bisphenol A, chlorinated phenols, and ethidium bromide. A detection limit in the magnitude of ca. 10 nM was achieved. This immobilization technique provides a generic approach for dsDNA-based sensor development and for the monitoring of DNA-analyte interactions.     

Polymer foaming with chemical blowing agents: Experiment and modeling

An experimental and theoretical analysis of the polypropylene foaming process using three different chemical blowing agents (CBA) was performed. A simple experiment was designed to analyze the foaming process of polypropylene (PP)/CO₂ system under two different pressure conditions. The expansion ratio and final foam structure was measured both by direct observation and from optical measurements and image analysis, showing a good agreement. A single bubble simulation based on relevant differential scanning calorimetry and thermo‐gravimetrical analysis experiments, assuming each CBA particles as a nucleation site and accounting for gas diffusion in the surrounding polymer matrix has been built. The sensitivity of the model to physical and processing parameters has been tested. The calculation results are compared to the experiments and open the route to a simplified method for evaluating the efficiency of CBA. POLYM. ENG. SCI., 55:2018–2029, 2015. © 2014 Society of Plastics Engineers     

Harmony search algorithm for minimum cost design of steel frames with semi-rigid connections and column bases

Harmony search-based algorithm is developed to determine the minimum cost design of steel frames with semi-rigid connections and column bases under displacement, strength and size constraints. Harmony search (HS) is recently developed metaheuristic search algorithm which is based on the analogy between the performance process of natural music and searching for solutions of optimum design problems. The geometric non-linearity of the frame members, the semi-rigid behaviour of the beam-to-column connections and column bases are taken into account in the design algorithm. The results obtained by semi-rigid connection and column base modelling are also compared to one developed by rigid connection modelling. The efficiency of HS algorithm, in comparison with genetic algorithms (GAs), is verified with three benchmark examples. The results indicate that HS could obtain lighter frames and less cost values than those developed using GAs.     

Numerical analysis of indirect internal reforming with self-sustained electrochemical promotion catalysts

In this paper, we establish a numerical model for simulating an indirect internal reforming section in a solid oxide fuel cell to demonstrate the effect of the electrochemical promotion and coupling between selective anode catalysts and selective cathode catalysts in the catalyst pack. The model employs a simplified geometrical model of an indirect internal reforming section in the anode chamber of a solid oxide fuel cell. However, the model includes very complicated combination of conventional reforming processes, electrochemical promotion and coupling. The results predict that the electrochemical promotion and coupling in a microscopic scale can enable a significant reforming and production of hydrogen at a relatively low temperature (500 °C).     

DC cancellation in the single-bit domain using ternary filtering

A structure for single-bit DC blocking is presented. This type of DC blocker is useful in practice to improve the stability and dynamic range of single-bit systems. The DC blocker is essentially a ternary filtering structure whose input and output are both assumed to be sigma–delta modulated bitstreams. Two techniques have been utilised to design the ternary filter to allow for implementation and performance comparison. Performance is tested for different kinds of single-bit format input signals, including sinusoidal, FM and AM–FM signals. The proposed DC blocker contains no multipliers and can easily be implemented with FPGA technology.     

Integrating waveguide biosensor

A capillary biosensor is demonstrated which uses the waveguiding properties of the capillary to integrate the signal over an increased surface area without simultaneously increasing the background noise from the detector. This biosensor achieves limits of detection of 30-50 pg/mL in immunoassays using a diode laser for excitation and a PMT for detection. This is approximately 2 orders of magnitude greater sensitivity than was achieved using the same immunoassay reagents in a fiber optic biosensor or a planar array biosensor. Two different approaches to using the capillaries as immunosensors are described, either of which could be adapted for multianalyte sensing.