Bioavailability of sediment-associated PCDD/Fs and PCDEs: relative importance of contaminant and sediment characteristics and biological factors

Factors that determine accumulation of sediment-associated polychlorinated dibenzo-p-dioxins and furans and polychlorinated diphenyl ethers into semipermeable membrane devices (SPMDs) and benthic oligochaete worms (Lumbriculus variegatus) were examined. These factors included both physical-chemical and structural characteristics of the contaminants (water solubility, lipophilicity, dipole moment, molecular size, and conformation) and sediment characteristics (organic carbon content, particle size, aromaticity, and polarity of organic carbon). The results of partial least squares regression analysis indicated that lipophilicity alone is not a sufficient predictor for contaminant bioaccumulation potential, even though it is a significant contributor. It was shown that contaminant molecular size and conformation (specifically planarity/nonplanarity) as well as sediment characteristics also have a significant role. The studied factors contributed up to 63-88% of the variation in accumulation data for SPMDs and 50-65% for oligochaetes. Comparison of (bio)accumulation factors (BAF28d for oligochaetes and AF28d for SPMDs) revealed that accumulation of contaminants in oligochaetes is largely influenced by biological factors (e.g., feeding habits), while the physical-chemical nature of the process is emphasized for SPMDs.     

Acute effects of Aspergillus versicolor aerosols on murine airways

Mice were exposed to aerosols from Aspergillus versicolor extract by inhalation (for 15-20 min). Changes in respiratory function parameters were monitored during the exposure to evaluate acute effects on the upper and lower respiratory tracts and the conductive airways. The single inhalation exposure to A. versicolor aerosols at the range of 12-151 mg/m3 provoked upper respiratory tract irritation in the airways of mice. The higher the exposure concentration the higher was the increase in the sensory irritation (SI) response. No bronchoconstriction or pulmonary irritation was observed. The causative agents for the SI response in the fungal extract are not known.     

Sorting multisets stably in minimum space

We consider the problem of sorting a multiset of sizen containingm distinct elements, where theith distinct element appearsn _i times. Under the assumption that our model of computation allows only the operations of comparing elements and moving elements in the memory,(n logn – _i=1 ^m n _i logn _i +n) is known to be a lower bound for the computational complexity of the sorting problem. In this paper we present aminimum space algorithm that sortsstably a multiset in asymptoticallyOptimal worst-case time. A Quicksort type approach is used, where at each recursive step the median is chosen as the partitioning element. To obtain a stable minimum space implementation, we develop linear-time in-place algorithms for the following problems, which have interest of their own: Stable unpartitioning: Assume that ann-element arrayA is stably partitioned into two subarraysA ₀ andA ₁. The problem is to recoverA from its constitutentsA ₀ andA ₁. The information available is the partitioning element used and a bit array of sizen indicating whether an element ofA ₀ orA ₁ was originally in the corresponding position ofA. Stable selection: The task is to find thekth smallest element in a multiset ofn elements such that the relative order of identical elements is retained.A preliminary version of this paper was presented at the3rd Scandinavian Workshop on Algorithm Theory, Helsinki, July 1992.     

Exploitation of electric field in controlling of nanofiber spinning process

Nanofibers can be prepared from a polymer solution utilizing electrospinning, a method exploiting an electrostatic field. In this work the electric field of the electrospinning process was modeled for better understanding and controllability of the fiber deposition in the electrospinning process. The model of the electric field was compared with experimental observations. The model of the electric field explained many phenomena in electrospinning, but did not provide an exclusive control tool for the process. POLYM. ENG. SCI., 47:2065–2074, 2007. © 2007 Society of Plastics Engineers     

Black Ultra-Thin Crystalline Silicon Wafers Reach the 4n2 Absorption Limit–Application to IBC Solar Cells

Cutting costs by progressively decreasing substrate thickness is a common theme in the crystalline silicon photovoltaic  industry for the last decades, since drastically thinner wafers would significantly reduce the substrate-related costs. In addition to the technological challenges concerning wafering and handling of razor-thin flexible wafers, a major bottleneck is to maintain high absorption in those thin wafers. For the latter, advanced light-trapping techniques become of paramount importance. Here we demonstrate that by applying state-of-the-art black-Si nanotexture produced by DRIE on thin uncommitted wafers, the maximum theoretical absorption (Yablonovitch's 4n² absorption limit), that is, ideal light trapping, is reached with wafer thicknesses as low as 40, 20, and 10 µm when paired with a back reflector. Due to the achieved promising optical properties the results are implemented into an actual thin interdigitated back contacted solar cell. The proof-of-concept cell, encapsulated in glass, achieved a 16.4% efficiency with an J_SC = 35 mA cm⁻², representing a 43% improvement in output power with respect to the reference polished cell. These results demonstrate the vast potential of black silicon nanotexture in future extremely-thin silicon photovoltaics.     

Role of Brown and Beige Adipose Tissues in Seasonal Adaptation in the Raccoon Dog (Nyctereutes procyonoides)

Brown adipose tissue (BAT) expresses uncoupling protein-1 (UCP1), which enables energy to be exerted towards needed thermogenesis. Beige adipocytes are precursor cells interspersed among white adipose tissue (WAT) that possess similar UCP1 activity and capacity for thermogenesis. The raccoon dog (Nyctereutes procyonoides) is a canid species that utilizes seasonal obesity to survive periods of food shortage in climate zones with cold winters. The potential to recruit a part of the abundant WAT storages as beige adipocytes for UCP1-dependent thermogenesis was investigated in vitro by treating raccoon dog adipocytes with different browning inducing factors. In vivo positron emission tomography/computed tomography (PET/CT) imaging with the glucose analog ¹⁸F-FDG showed that BAT was not detected in the adult raccoon dog during the winter season. In addition, UCP1 expression was not changed in response to chronic treatments with browning inducing factors in adipocyte cultures. Our results demonstrated that most likely the raccoon dog endures cold weather without the induction of BAT or recruitment of beige adipocytes for heat production. Its thick fur coat, insulating fat, and muscle shivering seem to provide the adequate heat needed for surviving the winter.     

Effect of forage conservation method, concentrate level and propylene glycol on the fatty acid composition and vitamin content of cows' milk

Based on potential health benefits, there is a need to develop effective strategies for enhancing milk fat concentrations of cis-9 18:1, 18:3 n-3 and conjugated linoleic (CLA) content in milk without compromising the sensory or storage characteristics of processed milk or dairy products. Sixteen Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 21-d experimental periods and a 4 x 2 x 2 factorial arrangement of treatments to evaluate the effects of forage conservation method, concentrate level and supplements of propylene glycol (PG), and their interactions on milk fatty acid composition and vitamin content. Experimental treatments consisted of four conserved forages offered ad libitum, supplemented with two levels of a standard concentrate (7 or 10 kg/d) and PG (0 and 210 g/d) fed as three equal meals. Primary growths of timothy and meadow fescue sward were conserved by ensiling with none (NA), an inoculant enzyme preparation (IE) or a formic acid based (FORM) additive or as hay 1 week later. Conservation of grass by drying rather than ensiling resulted in lower forage 18:2n-6, 18:3n-3, total fatty acid and fat-soluble vitamin concentrations. In spite of lower intakes, milk fat 18:2n-6 and 18:3n-3 content was higher (P < 0.05) for hay than for silage diets (12.1, 9.6, 9.6 and 9.3 and 5.00, 3.51, 4.27 and 2.93 g/kg total fatty acids, for hay, NA, IE and FORM silages, respectively). Forage conservation method had no clear effects on milk trans 18:1 or CLA content. Compared with silage, hay diets resulted in milk containing lower (P < 0.001) riboflavin, alpha-tocopherol and beta-carotene concentrations, but had no effect on ascorbic acid, thiamine, pyridoxine or retinol content. Feeding more concentrates had no effect on milk fatty acid composition or milk vitamin content, other than lowering (P < 0.001) 16:0 concentrations from 348 to 338 g/kg fatty acids. Supplements of PG led to small (P < 0.05) increases in milk 13:0 anteiso and 15:0 content from 1.06 and 11.3 to 1.22 and 12.6 g/kg fatty acids and reduced (P < 0.05) the concentrations of ascorbic acid (16.1 v. 15.1 g/kg milk).     

Sewage Sludge Electro-Dewatering Treatment—A Review

Purification of municipal wastewater generates huge amounts of sewage sludge, which contains large quantities of water, biomass, and extracellular polymeric substances. It is widely known that sewage sludge usually has a poor dewaterability. A large amount of water in sludge directly translates into high transport and handling costs; therefore, sludge treatment and disposal usually requires over 50% of the operation budget for wastewater treatment plants. The application of a low electric field through the sludge segment, called electro-dewatering, is considered to improve the liquid–solid separation, resulting in low water content in the sludge cake. However, prediction of dewatering enhancement for sewage sludge, in particular, offers a challenge due to variations in sludge pretreatment practices and the lack of harmonized testing methodologies. In this review article, the aspects that have an effect on sewage sludge electro-dewatering and its feasibility are discussed in the light of recent technological developments. It was found that electro-dewatering has several potential benefits, such as removal of pathogens, reduction in energy and transportation costs, and prevention of filter fouling.     

Effects of fungal species,cultivation time,growth substrate,and air exposure velocity on the fluorescence properties of airborne fungal spores

Real‐time bioaerosol monitoring is possible with fluorescence based instruments. This study provides information on major factors that can affect the fluorescence properties of airborne fungal spores. Two fluorescence‐based bioaerosol detectors, BioScout, and ultraviolet aerodynamic particle sizer (UVAPS), were used to study fluorescent particle fractions (FPFs) of released spores of three fungal species (Aspergillus versicolor, Cladosporium cladosporioides, and Penicillium brevicompactum). Two culture media (agar and gypsum board), three ages of the culture (one week, one month, and four months), and three aerosolization air velocities (5, 15, and 27 m/s) were tested. The results showed that the FPF values for spores released from gypsum were typically lower than for those released from agar indicating that poor nutrient substrate produces spores with lower amounts of fluorescent compounds. The results also showed higher FPF values with lower air velocities in aerosolization. This indicates that easily released fully developed spores have more fluorescent compounds compared to forcibly extracted non‐matured spores. The FPFs typically were lower with older samples. The FPF results between the two instruments were similar, except with four‐month‐old samples. The results can be utilized in field measurements of fungal spores to estimate actual concentrations and compare different instruments with fluorescence‐based devices as well as in instrument calibration and testing in laboratory conditions.     

Nonlinear behavior of three-terminal graphene junctions at room temperature

We demonstrate nonlinear behavior in three-terminal T-branch graphene devices at room temperature. A rectified nonlinear output at the center branch is observed when the device is biased by a push-pull configuration. Nonlinearity is assumed to arise from a difference in charge transfer through the metal–graphene contact barrier between two contacts. The sign of the rectification can be altered by changing the carrier type using the back-gate voltage.