Single Cell Bioprinting with Ultrashort Laser Pulses

Tissue engineering requires the precise positioning of mammalian cells and biomaterials on substrate surfaces or in preprocessed scaffolds. Although the development of 2D and 3D bioprinting technologies has made substantial progress in recent years, precise, cell-friendly, easy to use, and fast technologies for selecting and positioning mammalian cells with single cell precision are still in need. A new laser-based bioprinting approach is therefore presented, which allows the selection of individual cells from complex cell mixtures based on morphology or fluorescence and their transfer onto a 2D target substrate or a preprocessed 3D scaffold with single cell precision and high cell viability (93–99% cell survival, depending on cell type and substrate). In addition to precise cell positioning, this approach can also be used for the generation of 3D structures by transferring and depositing multiple hydrogel droplets. By further automating and combining this approach with other 3D printing technologies, such as two-photon stereolithography, it has a high potential of becoming a fast and versatile technology for the 2D and 3D bioprinting of mammalian cells with single cell resolution.     

Social information use and the evolution of unresponsiveness in collective systems

Animal groups in nature often display an enhanced collective information-processing capacity. It has been speculated that natural selection will tune this response to be optimal, ensuring that the group is reactive while also being robust to noise. Here, we show that this is unlikely to be the case. By using a simple model of decision-making in a dynamic environment, we find that when individuals behave rationally and are subject to selection based on their accuracy, optimality of collective decision-making is not attained. Instead, individuals overly rely on social information and evolve to be too readily influenced by their neighbours. This is due to a classic evolutionary conflict between individual and collective interest. The result is a sub-optimal system that is poised on the cusp of total unresponsiveness. Individuals in the evolved group exhibit delayed reactions to changes in the environment, before responding with rapid, socially reinforced transitions, reminiscent of familiar human and animal social systems (markets, stampedes, fashions, etc.). Our results demonstrate that behaviour of this type may not be pathological, but instead could represent an evolutionary attractor for such collective systems.     

Phosphoproteomic Analysis of Subcutaneous and Omental Adipose Tissue Reveals Increased Lipid Turnover in Dairy Cows Supplemented with Conjugated Linoleic Acid

Phosphoproteomics is a cutting-edge technique that can be utilized to explore adipose tissue (AT) metabolism by quantifying the repertoire of phospho-peptides (PP) in AT. Dairy cows were supplemented with conjugated linoleic acid (CLA, n = 5) or a control diet (CON, n = 5) from 63 d prepartum to 63 d postpartum; cows were slaughtered at 63 d postpartum and AT was collected. We performed a quantitative phosphoproteomics analysis of subcutaneous (SC) and omental (OM) AT using nanoUPLC-MS/MS and examined the effects of CLA supplementation on the change in the phosphoproteome. A total of 5919 PP were detected in AT, and the abundance of 854 (14.4%) were differential between CON and CLA AT (p ≤ 0.05 and fold change ± 1.5). The abundance of 470 PP (7.9%) differed between OM and SC AT, and the interaction treatment vs. AT depot was significant for 205 PP (3.5% of total PP). The integrated phosphoproteome demonstrated the up- and downregulation of PP from proteins related to lipolysis and lipogenesis, and phosphorylation events in multiple pathways, including the regulation of lipolysis in adipocytes, mTOR signaling, insulin signaling, AMPK signaling, and glycolysis. The differential regulation of phosphosite on a serine residue (S777) of fatty acid synthase (FASN) in AT of CLA-supplemented cows was related to lipogenesis and with more phosphorylation sites compared to acetyl-coenzyme A synthetase (ACSS2). Increased protein phosphorylation was seen in acetyl-CoA carboxylase 1 (ACACA;8 PP), FASN (9 PP), hormone sensitive lipase (LIPE;6 PP), perilipin (PLIN;3 PP), and diacylglycerol lipase alpha (DAGLA;1 PP) in CLA vs. CON AT. The relative gene expression in the SC and OM AT revealed an increase in LIPE and FASN in CLA compared to CON AT. In addition, the expression of DAGLA, which is a lipid metabolism enzyme related to the endocannabinoid system, was 1.6-fold higher in CLA vs. CON AT, and the expression of the cannabinoid receptor CNR1 was reduced in CLA vs. CON AT. Immunoblots of SC and OM AT showed an increased abundance of FASN and a lower abundance of CB1 in CLA vs. CON. This study presents a complete map of the SC and the OM AT phosphoproteome in dairy cows following CLA supplementation and discloses many unknown phosphorylation sites, suggestive of increased lipid turnover in AT, for further functional investigation.     

A New Method to Determine the Number Concentrations of Refractory Black Carbon Ice Nucleating Particles

Ice nucleating particles (INP) initiate heterogeneous ice nucleation in mixed-phase clouds, influencing cloud phase and onset temperatures for ice formation. Determination of particle types contributing to atmospheric INP populations requires isolation of the relatively rare INP from a total particle sample, typically followed by time-consuming single-particle characterization. We propose a method to estimate the contributions of light-absorbing, primarily refractory black carbon (rBC), particles to INP populations by selectively removing them prior to determination of INP concentrations. Absorbing particles are heated to their vaporization temperature using laser induced incandescence in a single particle soot photometer (SP2) and the change in INP number concentrations, compared to unheated samples, is assessed downstream in the CSU Continuous Flow Diffusion Chamber (CFDC). We tested this approach in the laboratory using strongly-absorbing and nonabsorbing aerosol types to confirm effective removal of rBC INP and to explore the impact of the processing on non-light-absorbing INP. An INP-active rBC particle type was efficiently removed, while nonabsorbing kaolinite and a soil-based INP were not affected by laser exposure. Results for the products of wiregrass combustion indicated that absorbing particles, primarily rBC, accounted for about 40% of all INP, consistent with electron microscopy of INP emitted during prescribed burns of this fuel type. However, kaolinite internally mixed with rBC exhibited reduced activity after passing through the SP2, suggesting that the validity of the method for realistic internal mixtures needs additional research. The sensitivity of the CFDC presently limits applicability of the method to relatively high INP number concentration samples.

Copyright 2014 American Association for Aerosol Research     

A pilot study to investigate the effects of combined dehumidification and HEPA filtration on dew point and airborne mold spore counts in day care centers

Meteorological factors such as relative humidity directly correlate with airborne fungal levels outdoors and indoors. While dehumidification alone is effective at reducing moisture necessary for mold growth, it is inadequate as a single intervention as it does not remove viable and non-viable fungal spores that are potentially allergenic. The purpose of this pilot study was to investigate whether dehumidification in combination with high-efficiency particulate arrestance (HEPA) filtration is effective at reducing airborne mold spore levels in day care centers. Two day care centers within a 2-mile radius of each other were selected. Day care center A was 2 years old with eight rooms while day care center B was 15 years old with six rooms. A high efficiency Santa Fe dehumidification unit equipped with a HEPA filter was installed in half the rooms (intervention) of each day care facility. Electronic HOBO data loggers continuously measured outdoor and indoor room dew point and temperature every 2 h throughout the study. Dew point and airborne fungal spore measurements from selected rooms with controlled air conditions were analyzed by comparing baseline measurements to those obtained at subsequent time periods over 1 year. Regression models accounted for correlations between measurements in the same room over time. Intervention resulted in a lowered average dew point from baseline by 8.8 degrees C compared with a decrease of 7.1 degrees C in non-intervention rooms across all time periods in both facilities (P<0.001). Fungal analyses demonstrated lower baseline (P=0.06) and follow-up means in intervention rooms (P<0.05), however the change from baseline to end of follow-up differed between intervention and non-intervention rooms in the two facilities. Log transformation was applied to approximate normality of fungal measurements. Dehumidification with HEPA filtration was effective at controlling indoor dew point in both facilities and at reducing airborne culturable fungal spore levels in one of the two facilities. These preliminary results provide a scientific rationale for using this intervention in future studies designed to investigate the impact of indoor mold exposure on health outcomes. PRACTICAL IMPLICATIONS: Poor indoor air quality is a recognized cause or contributing factor to health effects. Dampness and humidity have been linked to upper and lower respiratory symptoms in children and adults. This study indicates that reducing indoor relative humidity and airborne mold spore levels using high-efficiency dehumidification units equipped with HEPA filtration is feasible even in work facilities such as day care centers where traffic in and out of the building is difficult to regulate. Clinicians should emphasize to their patients the importance of dehumidification and HEPA filtration to improve indoor air quality in the home and workplace.     

Photoelectrochemical Activity of Nanosized Titania,Doped with Bismuth and Lead,in Visible Light Region

Protection of Metals and Physical Chemistry of Surfaces - A method for the preparation of film coatings of titania doped with bismuth (Bi3+) and lead (Pb2+) ions, separately and simultaneously, has...     

Photoelectrocatalytic Oxidation of Formic Acid in the Visible Spectral Region on Films of Nanocrystalline Titanium Oxide Doped by Bismuth

Protection of Metals and Physical Chemistry of Surfaces - A method of formation of film coatings of titanium dioxide doped by bismuth ions (Bi3+) is developed on the basis of sol–gel...     

Optimization in terms of interval uncertainty: The determinization method

The current approaches to the optimization of systems under uncertainty are considered. An exact formulation of the problem of the conditional optimization of the target function parameters and limitations under interval uncertainty is given. A determinization method allowed us to solve the problem by reducing it to two completely determined ones of conditional optimization of the same type is stated and proved.