Asymmetric magnetization reversal of stripe-patterned exchange bias layer systems for controlled magnetic particle transport

Domain wall movement assisted transport of particles: exchange-biased samples with designed stripe-domains show strong stray fields and an asymmetric magnetization reversal. Using these characteristics superparamagnetic particles can be trapped and transported directly on the sample over large-scale areas. High particle velocities, small external fields, and automatically reduced particle clustering allow broad applicability of this transport method.     

Synthesis of Photopolymerizable Hydrophilic Macromers and Evaluation of Their Applicability as Reactive Resin Components for the Fabrication of Three‐Dimensionally Structured Hydrogel Matrices by 2‐Photon‐Polymerization

Two‐photon polymerization (2‐PP) is a promising new photolithographic technique to fabricate three‐dimensional (3D), micro‐ and nano‐structured tissue engineering scaffolds from photopolymerizable monomers. Although various photo resins are known for the use in 2‐PP, there is currently a need for photo‐curable monomers processable by 2‐PP to generate biocompatible 3D‐structured hydrogel materials for soft or cartilage tissue regeneration. In the present work hydrophilic methacrylate monomers and macromers based on synthetic poly(glycerine) and poly(ethylene glycol) urethanes as well as on the biopolymers dextran and hyaluronan is prepared. The photopolymerization behavior of these substances are investigated and formed hydrogel networks are studied with regard to their mechanical properties, cytocompatibility, and hydrolytic degradation. Based on these examinations simple 3D model structures are fabricated from these photo‐curable monomers and macromers by 2‐PP. It is shown that both the synthetic monomers and the dextran methacrylate macromer are efficient 2‐PP starting materials whereas the hyaluronan methacrylate can be used for 2‐PP only in combination with suitable water‐soluble co‐monomers. No cytotoxic effects are found in preliminary chondrocyte cultivation experiments on 2‐PP‐fabricated scaffolds but initial cell adhesion on the hydrophilic scaffold surfaces is rather low and has to be further improved to apply these structures in tissue engineering.     

Hydrogen underground storage—Petrographic and petrophysical variations in reservoir sandstones from laboratory experiments under simulated reservoir conditions

Fluctuating energy production by renewables is one of the main issues in transition times of energy production from conventional power plants to an energy production by renewables. Using excess produced electricity (windy/sunny periods) to convert water to oxygen and hydrogen and storing the hydrogen in depleted oil-, gas fields or sedimentary aquifer structures would provide the option to recover and convert hydrogen to electricity in periods with an energy demand. Research focus is here the pore space in the geological underground where still few studies exist. In static batch experiments up to six weeks long, under different reservoir-specific conditions; regarding pressure, temperature and formation fluid salinity, sandstones were exposed to 100% hydrogen. Before and after these experiments microscopic, petrophysical and computer tomography analyses are conducted. The preliminary results from different scales (μm to cm) and dimensions (2D and 3D) of 21 samples indicate that hydrogen underground storage is likely possible.     

Organic solid waste originating from the meat processing industry as an alternative energy source

The biosolids originating from the wastewater treatment process of two meat processing plants (LFP and LFG) were characterized as a fuel and their potential for utilization as alternative energy sources was assessed through the combustion of LFP in a pilot scale cyclone combustor. A comparative evaluation of the LFP, LFG and SD (sawdust) properties as well as the emissions during the combustion test was performed. The high energy content of LFP (LHV (lower heating value) equal to 25.77 MJ kg⁻¹) and LFG (LHV = 25.89 MJ kg⁻¹), both dry and ash free (daf), combined with the high volatile matter content (85.29 and 85.61 wt%, daf, respectively) improve the ignition and burning of the solids. Also, the fouling and slagging tendencies of the ashes were predicted based on the fuel ash composition and ash fusibility correlations. The emissions of CO, SO₂, and NO_x and total organic carbon (TOC) were compared to guideline limits established by Brazilian and international legislation. The TOC concentrations were below the emission limits. The high level of nitrogen in LFP (9.24 wt%, daf) led to high levels of NO_x. In this regard, further combustion tests are being performed by the authors.     

A 12-Gb/s high-performance, high-sensitivity monolithic p-i-n/HBTphotoreceiver module for long-wavelength transmission systems

A very high sensitivity, high speed, fiber-pigtailed photoreceiver module is described. The OEIC photoreceiver, composed of a p-i-n photodetector monolithically integrated with an InP-InGaAs heterojunction bipolar transistor (HBT)-based transimpedance amplifier, has measured sensitivity of -20 dBm and -17.6 dBm for data rates of 10 and 12 Gb/s, respectively, at a bit error rate of 1×10^-9. These results are the best ever reported for an OEIC photoreceiver at these speeds. In an optical transmission experiment with a low noise erbium-doped fiber amplifier (EDFA) preceding the OEIC photoreceiver, the measured sensitivities were -35.2 and -32 dBm at 10 and 12 Gb/s respectively     

Effect of monensin on the performance and nitrogen utilization of lactating dairy cows consuming fresh forage

We conducted a lactation trial with a fresh forage diet in order to evaluate 1) the effects of monensin on nitrogen metabolism, and 2) the Cornell Net Carbohydrate and Protein System (CNCPS). Thirty Holstein cows in midlactation (eight fitted with ruminal fistulas) were gradually introduced to a fresh forage diet. A concentrate mix based on corn meal was fed before the a.m. and p.m. milking times 0730 and 1730 h, then the fresh forage was fed at 0830 and 1830 h. Fifteen cows each were allocated to a control (no monensin) and a treatment group receiving 350 mg/cow per day of monensin in the p.m. concentrate feeding. A 7-d fecal and urine collection period and a 3-d rumen sampling period were conducted with the fistulated cows. After the lactation study was concluded, the fistulated cows were fed forage regrowth and a 3-d rumen sampling period was repeated. Monensin increased milk production by 1.85 kg. Milk fat and protein concentrations decreased and milk fat and protein yields increased, but the effects were nonsignificant. Monensin did not significantly affect DMI. Ruminal ammonia and the acetate-to-propionate ratio decreased with the addition of monensin in both fed forages. Monensin decreased fecal N output, and increased apparent N digestibility by 5.4%. Because of the decrease in ruminal ammonia and increase in apparent N digestibility, we concluded monensin was sparing amino acids from wasteful rumen degradation with a fresh forage diet. The precision of the CNCPS in predicting performance was high (r2 = 0.76), and the bias was low (overprediction of 3.6%). These results indicate that the CNCPS can be used for dairy cows consuming fresh forage and gives realistic predictions of performance.     

Progress towards robotic exploration of extreme terrain

A high degree of mobility, reliability, and efficiency are needed for autonomous exploration of extreme terrain. These requirements have guided the development of the Ambler, a six-legged robot designed for planetary exploration. To address issues of efficiency and mobility, the Ambler is configured with a stacked arrangement of orthogonal legs and exhibits a unique circulating gait, where trailing legs recover directly from rear to front. The Ambler is designed to stably traverse a 30 degree slope while crossing meter sized features. The same three principles have provided many constraints on the design of a software system that autonomously navigates the Ambler through natural terrain using 3-D perception and a combined deliberative/reactive architecture. The software system has required research advances in real-time control, perception of rugged terrain, motion planning, task-level control, and system integration. This paper presents many of the factors that influenced the design of the Ambler and its software system. In particular, important assumptions regarding the mechanism, perception, planning, and control are presented and evaluated in light of experimental and theoretical research of this project.     

Prolongation and optimization of Doppler enhancement with a microbubble US contrast agent by using continuous infusion: preliminary experience

The ptp gene of Acinetobacter johnsonii was previously reported to encode a low-molecular-mass protein, Ptp, whose amino acid sequence, predicted from the theoretical analysis of the nucleotide sequence of the gene, exhibits a high degree of similarity with those of different eukaryotic and prokaryotic phosphotyrosine-protein phophatases. We have now overexpressed the ptp gene in Escherichia coli cells, purified the Ptp protein to homogeneity by a single-step chromatographic procedure, and analysed its functional properties. We have shown that Ptp can catalyse the dephosphorylation of p-nitrophenyl phosphate and phosphotyrosine, but has no effect on phosphoserine or phosphothreonine. Its activity is blocked by ammonium molybdate and sodium orthovanadate, which are strong inhibitors of phosphotyrosine-protein phosphatases, as well as by N-ethylmaleimide and iodoacetic acid. Such specificity of Ptp for phosphotyrosine has been confirmed by the observation that it can dephosphorylate endogenous proteins phosphorylated on tyrosine, but not proteins modified on either serine or threonine. In addition, Ptp has been shown to quantitatively dephosphorylate two exogenous peptides, derived respectively from leech hirudin and human gastrin, previously phosphorylated on tyrosine. Moreover, site-directed mutagenesis experiments performed on Cys11 and Arg16, which are both present in the sequence motif (H/V)C(X5)R(S/T) typical of eukaryotic phosphotyrosine-protein phosphatases, have demonstrated that each amino acid residue is essential for the catalytic activity of Ptp. Taken together, these data provide evidence that Ptp is a member of the phosphotyrosine-protein phosphatase family. Furthermore, in search for the biological function of Ptp, we have found that it can specifically dephosphorylate an endogenous protein kinase, termed Ptk, which is known to autophosphorylate at multiple tyrosine residues in the inner membrane of Acinetobacter johnsonii cells. This represents the first identification of a protein substrate for a bacterial phosphotyrosine-protein phosphatase, and therefore constitutes a possible model for analysing the role of reversible phosphorylation on tyrosine in the regulation of microbial physiology.     

Numerical analysis of mixing in block‐head mixing screws

The research reported here used 3D non‐Newtonian flow simulations to investigate the pumping and mixing capability of block‐head mixers. Block‐head mixers are distributive mixing screws that are widely used to homogenize the polymer melt and eliminate thermal gradients. The polymer‐processing industry employs a variety of block‐head mixers, with little consensus on design and distribution of screw flights and mixing blocks. This analysis addresses this issue based on a computational design study in which the influence of three geometrical parameters was examined: (1) the number of flights at a mixing block, (2) the number of blocks along the screw, and (3) the stagger angle between the blocks. To examine the flow behavior of the mixing screws, the pressure consumption and energy dissipation is evaluated. Distributive mixing is analyzed using residence time distribution functions, kinematic stretching parameters, and the scale of segregation. Dispersive mixing is assessed by means of the mixing index and the shear stress. The results of this design study increase the understanding of block‐head mixers and contribute to the design and optimization of such geometries. The findings can further be applied to mixing screws of similar geometry, including pin‐type and knob mixers. POLYM. ENG. SCI., 59:E88–E104, 2019. © 2018 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.     

DETERMINATION OF DIBENZO[A,L]PYRENE AND OTHER FJORD-REGION PAH ISOMERS WITH MW 302 IN ENVIRONMENTAL SAMPLES

Polycyclic aromatic hydrocarbons (PAHs) occur in the environment as complex mixtures including compounds with mutagenic and carcinogenic activity. The PAH profile routinely determined in environmental samples at present encompasses isomers with molecular weight (MW) not greater than 300. However, PAHs with MW >300 have been demonstrated for several matrices to contribute up to 50% of the total activity when tested for carcinogenicity in experimental animals. Recent studies indicate that among the dibenzopyrenes with MW 302 dibenzo[a,l]pyrene, possessing a fjord region, is by far the most carcinogenic PAH hitherto identified. To further elucidate the environmental relevance of this compound we have applied the isotope dilution GC/MS technique as analytical procedure to determine this compound and the related fjord region PAH naphtho[1,2-a]- and naphtho[1,2-e]pyrene in various matrices. Identification was based on comparison of UV and mass spectra as well as retention times of authentic reference materials. Determination of these PAHs was achieved after clean-up by several chromatographic steps including fractionation on a modified TABA-silica gel column. Quantitative data for matrices such as two cigarette smoke condensates, motor vehicle exhaust condensate (Otto-type engines), and tar-cork are reported. Based on toxic equivalent factors the relative contribution of dibenzo[a,l]pyrene (5.4–42.3%) to the total carcinogenic activity of a PAH profile will be discussed comprising 14 selected isomers (benzo[b]naphtho[2,1-d]thiophene; cyclopenta[cd]pyrene; benz[a]anthracene; chrysene/triphenylene; sum of benzo[b]-, benzo[k]-, and benzo[j]fluoranthene; benzo[a]pyrene; indeno[1,2,3-cd]pyrene; dibenz[a,h]anthracene; benzo[ghi]perylene; anthanthrene; dibenzo[a,l]pyrene determined in these matrices.