Forest‐based resources as fillers in biobased polyurethane foams

Six fillers from forestry wastes (wood, bark, cones and needles from young pine trees, kraft lignin, and recycled paper sludge from industry wastes) were incorporated into polyurethane (PU)‐based foams prepared via free‐rise pouring method. Variable filler contents (1, 5, and 10 wt %) and NCO/OH ratios (0.6, 0.9, and 1.2) were investigated. A simple mixture (1:3) of castor oil and crude glycerin (byproduct from biodiesel production) was used as biobased polyol. The foam composites were investigated through spectroscopy, morphological, mechanical, and hygroscopic analyses. The addition of fillers decreased water uptake and yielded rigid PU systems with more homogenous cell structure. The 1% and 5% reinforcement wood were the most effective among the studied compositions, with better mechanical and hygroscopic performance, probably due the higher compatibility of the wood with the PU system, which promote urethanic bonds between filler and isocyanate, as indicated by wet chemical results and micrographs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45684.     

Can a Shared-Memory Model Serve as a Bridging Model for Parallel Computation?

A parallel multithreaded program that is ostensibly deterministic may nevertheless behave nondeterministically due to bugs in the code. These bugs are called determinacy races, and they result when one thread updates a location in shared memory while another thread is concurrently accessing the location. We have implemented a provably efficient determinacy-race detector for Cilk, an algorithmic multithreaded programming language. If a Cilk program is run on a given input data set, our debugging tool, which we call the ``Nondeterminator,' either determines at least one location in the program that is subject to a determinacy race, or else it certifies that the program is race free when run on the data set. The core of the Nondeterminator is an asymptotically efficient serial algorithm (inspired by Tarjan's nearly linear-time least-common-ancestors algorithm) for detecting determinacy races in series-parallel directed acyclic graphs. For a Cilk program that runs in T time on one processor and uses v shared-memory locations, the Nondeterminator runs in O(T α(v,v)) time, where α is Tarjan's functional inverse of Ackermann's function, a very slowly growing function which, for all practical purposes, is bounded above by 4 . The Nondeterminator uses at most a constant factor more space than does the original program. On a variety of Cilk program benchmarks, the Nondeterminator exhibits a slowdown of less than 12 compared with the serial execution time of the original optimized code, which we contend is an acceptable slowdown for debugging purposes. Received November 11, 1997, and in final form September 21, 1998.     

Proteolysis of Hispanico cheese manufactured using lacticin 481-producing Lactococcus lactis ssp. lactis INIA 639

Hispánico cheese was manufactured using lacticin 481-producing Lactococcus lactis ssp. lactis INIA 639, bacteriocin-nonproducing L. lactis ssp. lactis INIA 437, or a combination of both strains, as starter cultures. Lactobacillus helveticus LH 92, a culture of high amino-peptidase activity sensitive to lacticin 481, was added to all vats. Milk inoculation with the bacteriocin producer promoted early lysis of Lb. helveticus cells in cheese. Cell-free aminopeptidase activity in cheese made with the 3 lactic cultures was 1.8 times the level reached in cheese made only with L. lactis strain INIA 437 and Lb. helveticus, after 15 d of ripening. Proteolysis (as estimated by the o-phthaldialdehyde method) in cheese made with the 3 lactic cultures was twice as high, and the level of total free amino acids 2.4 times the level found in cheese made only with L. lactis strain INIA 437 and Lb. helveticus, after 25 d of ripening. Hydrophobic and hydrophilic peptides and their ratio were at the lowest levels in cheese made with the 3 lactic cultures, which received the lowest scores for bitterness and the highest scores for taste quality.     

Electrical and thermal characterization of Sm doped ceria electrolytes synthesized by combustion technique

Nanocrystalline samarium doped ceria electrolyte [Ce_0.9Sm_0.1O_1.95] was synthesized by citrate gel combustion technique involving mixtures of cerium nitrate oxidizer (O) and citric acid fuel (F) taken in the ratio of O/F = 1. The as-combusted precursors were calcined at 700 °C/2 h to obtain fully crystalline ceria nano particles. It was further made into cylindrical pellets by compaction and sintered at 1200 °C with different soaking periods of 2, 4 and 6 h. The sintered ceria was characterized for the microstructures, electrical conductivity, thermal conductivity and thermal diffusivity properties. In addition, the combustion derived ceria powder was also analysed for the crystallinity, BET surface area, particle size and powder morphology. Sintered ceria samples attained nearly 98% of the theoretical density at 1200 °C/6 h. The sintered microstructures exhibit dense ceria grains of size less than 500 nm. The electrical conductivity measurements showed the conductivity value of the order of 10⁻² S cm⁻¹ at 600 °C with activation energy of 0.84 eV between the temperatures 100 and 650 °C for ceria samples sintered at 1200 °C for 6 h. The room temperature thermal diffusivity and thermal conductivity values were determined as 0.5 × 10⁻⁶ m² s⁻¹ and 1.2 W m⁻¹ K⁻¹, respectively.     

Electrical Spin Injection from Ferromagnetic Nanocontacts into Nondegenerated Silicon at Low Temperatures

We present results on the magnetoresistance of the system Ni/Al₂O₃/Si/Al₂O₃/Ni fabricated in lateral nanostructures. The substrate n-type Si is a nondegenerated semiconductor with a doping level of 10¹⁵ cm^?3. The results are presented between 11 and 30 K, where the electrical resistivity of the semiconductor varies about 4 orders of magnitude. The reduction of magnetoresistance at 30 K is consistent with the standard theory for spin injection between a metal and a semiconductor. By fitting the data with $e^{ - t_{N} / L_{\mathrm{SD}}}$ , the diffusion condition, as a function of the channel length t _N , where the magnetoresistance takes place, we deduced the values of spin diffusion length L _SD and spin lifetime τ _s .     

Wide optical bandgap p-type μc-Si:Ox:H prepared by Cat-CVD and comparisons to p-type μc-Si:H

Oxygen-impurity boron-doped hydrogenated microcrystalline silicon (p-μc-Si:O_x:H) films have been deposited using catalytic chemical vapor deposition (Cat-CVD). Pure silane (SiH₄), hydrogen (H₂), oxygen (O₂), and diluted diborane (B₂H₆) gases were used. The tungsten catalyst temperature (T_fil) was varied from 1900 to 2100 °C and films were deposited on glass substrates at temperatures of 100 to 300 °C. Different catalyst-to-substrate distances were employed and single- or double-coiled filaments were used. In addition to p-μc-Si:O_x:H deposition, we have also deposited conventional p-type microcrystalline silicon (p-μc-Si:H) in order to compare their electrical and optical properties to p-μc-Si:O_x:H.     

Estimating preferences for local public services using migration data

Using Swedish micro data, the paper examines the impact of local public services on community choice. The choice of community is modelled as a choice between a discrete set of alternatives. It is found that, given taxes, high spending on child care attracts migrants. Less conclusive results are obtained with respect to the role of spending on education and elderly care. High local taxes deter migrants. Relaxing the independence of the irrelevant alternatives assumption, by estimating a mixed logit model, has a significant impact on the results.     

Dihydroazulene Photoswitch Operating in Sequential Tunneling Regime: Synthesis and Single‐Molecule Junction Studies

Molecular switches play a central role for the development of molecular electronics. In this work it is demonstrated that the reproducibility and robustness of a single‐molecule dihydroazulene (DHA)/vinylheptafulvene (VHF) switch can be remarkably enhanced if the switching kernel is weakly coupled to electrodes so that the electron transport goes by sequential tunneling. To assure weak coupling, the DHA switching kernel is modified by incorporating p‐MeSC₆H₄ end‐groups. Molecules are prepared by Suzuki cross‐couplings on suitable halogenated derivatives of DHA. The synthesis presents an expansion of our previously reported bromination–elimination–cross‐coupling protocol for functionalization of the DHA core. For all new derivatives the kinetics of DHA/VHF transition has been thoroughly studied in solution. The kinetics reveals the effect of sulfur end‐groups on the thermal ring‐closure of VHF. One derivative, incorporating a p‐MeSC₆H₄ anchoring group in one end, has been placed in a silver nanogap. Conductance measurements justify that transport through both DHA (high resistivity) and VHF (low resistivity) forms goes by sequential tunneling. The switching is fairly reversible and reenterable; after more than 20 “ON‐OFF” switchings, both DHA and VHF forms are still recognizable, albeit noticeably different from the original states.     

Outgrowth inhibition of Clostridium beijerinckii spores by a bacteriocin-producing lactic culture in ovine milk cheese

In the manufacture of model cheeses, ovine milk was deliberately contaminated with spores of Clostridium beijerinckii INIA 63, a wild isolate from Manchego cheese with late blowing defect, and inoculated with nisin- and lacticin 481-producing Lactococcus lactis subsp. lactis INIA 415 as starter, to test its potential to prevent the late blowing defect, or with L. lactis subsp. lactis INIA 415-2, a spontaneous mutant not producing bacteriocins. Cheeses made individually with the lactococcal strains, without clostridial spores, served as controls. Cheese made with clostridial spores and L. lactis subsp. lactis INIA 415-2 showed late blowing defect after 120 days of ripening. Spoilt cheese also showed lower concentrations of lactic acid, and higher levels of acetic, propionic and butyric acids, and of other volatile compounds such as 2-propanol and 1-butanol, than control cheese. In addition, cheese made with the bacteriocin producer did not show any late blowing symptoms, despite its spore counts similar to those of blown cheese, pointing to outgrowth inhibition of C. beijerinckii spores by bacteriocins. Besides, cheese made with the bacteriocin producer showed similar concentrations of lactic acid and volatile compounds than control cheese. Inclusion of L. lactis subsp. lactis INIA 415 in starter cultures seems a feasible method to prevent late blowing defect in cheese without altering its sensory characteristics.