Utilization of Pisat temperature-dependency in modelling adsorption on zeolites

In this study, the feasibility of utilizing pure component saturated vapour pressure P_i^sat in representing the temperature-dependency of physisorption of vapours on zeolites is examined. Adsorption data of water, alcohols and aromatic compounds both on hydrophilic on and hydrophobic zeolites has been collected from the literature and represented as a function of P/P_i^sat. It is found that the temperature-dependency of adsorption of a component can be described by the saturated vapour pressure, especially for water adsorption on zeolites. For systems where chemisorption also plays an important role, such as aromatics adsorption on zeolites, P_i^sat alone is not capable of predicting the temperature-dependency accurately enough. It is also observed that contrary to common practice, the maximum adsorption loading q_i^sat on zeolite should be considered independent of temperature. The proposed approach can be used in the modelling and design of industrial processes exploiting adsorption, such as in zeolite membrane systems, where separation is based on both adsorption and diffusion phenomena.     

Power Allocation in a Wireless Network Using Scheduling and Stochastic Programming with Penalty Functions

This paper studies the optimal allocation of transmit power in a wireless communication network. First, a stochastic programming formulation is introduced, based on penalizing violations of quality-of-service constraints. The maximization of the certainty equivalent signal-to-interference ratio under Rayleigh fading corresponds to a penalty model where (max-min) fairness is explicitly taken into consideration. Second, optimum dynamic power allocation is discussed. Efficient dynamic resource allocation under both linear and logarithmic utility functions is addressed. The dynamic model studies the optimal trade-off between instantaneous quality-of-service and a delay-penalized reliable quality-of-service. Related work on optimal stochastic power control is summarized.     

Tailoring surface properties of paper using nanosized precipitated calcium carbonate particles

Pigment particles used in paper coatings are typically of micrometer size and consequently the thickness of the coatings is, even at its lowest, in micrometer scale. Progress in nanotechnology has given way to the development of nanosized materials to be used in coatings, yet their exploitation has not been studied to a great extent. This study examines utilization of nanosized precipitated calcium carbonate (nanoPCC) particles in nanoscale thin coating layers. In contrast to commonly used coatings, a thin nanoparticle-based coating was targeted to change the substrate surface characteristics via controlled surface structure rather than via high coat weight. A novel approach for stabilizing and modifying the nanoPCC particles with pectin and alkenyl succinic anhydride (ASA) was utilized and a nanoparticle coating with uniform particle distribution was created. The coating applied on paper substrate was hydrophobic, having a water contact angle of 125°. Particle surface modification provided dispersion stability, enabling control of the coating layer structure. The introduced concept provides a new approach to paper coatings utilizing controlled deposition of nanoparticles with extremely low coat weight, yet having high impact on substrate surface properties. Additionally, as paper is an environmentally sound product, the approach to form a controllable nanostructure on a green substrate has potential in applications outside the traditional paper products.     

Infrared laser ablation atmospheric pressure photoionization mass spectrometry

In this paper we introduce laser ablation atmospheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass spectrometry. In LAAPPI the analytes are ablated from water-rich solid samples or from aqueous solutions with an infrared (IR) laser running at 2.94 μm wavelength. Approximately 12 mm above the sample surface, the ablation plume is intercepted with an orthogonal hot solvent (e.g., toluene or anisole) jet, which is generated by a heated nebulizer microchip and directed toward the mass spectrometer inlet. The ablated analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 eV vacuum ultraviolet krypton discharge lamp. The effect of operational parameters and spray solvent on the performance of LAAPPI is studied. LAAPPI offers ~300 μm lateral resolution comparable to, e.g., matrix-assisted laser desorption ionization. In addition to polar compounds, LAAPPI efficiently ionizes neutral and nonpolar compounds. The bioanalytical application of the method is demonstrated by the direct LAAPPI analysis of rat brain tissue sections and sour orange (Citrus aurantium) leaves.     

Measuring the thickness swelling and set-recovery of densified and thermally modified Scots pine solid wood

The purpose of this study was to analyse the fundamental phenomena related to the swelling behaviour of densified and thermally modified wood under changing moisture content, as well as to investigate the differences in recovery behaviour between four different methods: (i) soaking–drying cycles, (ii) soaking–drying cycles in hot water, (iii) water-soaking with continuous data logging to measure dynamic changes in thickness and (iv) humid–dry cycles at different relative humidity (RH). Methods were applied to untreated, thermally modified, densified (D) and densified + thermally modified (DTM) Scots pine sap wood samples. Soaking methods were found to produce significantly higher set-recovery results than RH cycling, with higher temperature accelerating the relaxation during soaking. Repeated cycles increased the swelling of the densified samples. The RH thresholds for set-recovery were found to be between 65 and 75 % for the D samples and between 75 and 84 % in the case of DTM samples.     

High-performance real-time quantitative RT-PCR using lanthanide probes and a dual-temperature hybridization assay

We report a time-resolved fluorescence-based, homogeneous approach for multiplex, real-time or end-point detection of PCR products. Signal generation consists of PCR associated digestion of a 5'-labeled oligonucleotide probe, rapid cooling of the reaction mixture, and hybridization of undigested probe oligonucleotides with a complementary, shorter probe that incorporates a quencher at its 3' end. The signal coming from intact fluorescent probe molecules is, thus, quenched. The fluorophores we have used are environmentally sensitive lanthanide chelates. Their signals can be measured in a time-resolved manner that eliminates most of the unspecific fluorescent background. Signal-to-noise ratios are further enhanced by the environmental sensitivity of these chelates; they exhibit a higher fluorescence intensity when free in solution than when coupled to intact probe molecules. Because of the minimal background fluorescence, the signal-to-noise ratios are higher and threshold cycles are lower than those obtained using conventional TaqMan probes. The multiplexing capacity of the assay chemistry is demonstrated through simultaneous amplification and detection of prostate specific antigen (PSA) cDNA and an internal standard mRNA (mmPSA) using probes labeled with terbium and europium. The applicability of the assay chemistry to routine clinical diagnostics is demonstrated through absolute quantification of PSA mRNA in peripheral blood.     

Primary and secondary context in mobile video communication

The new video capabilities of mobile phones are starting to change the field of mobile communication. It is now dramatically easier to publish video in quasi-real time. We discuss how this change will affect the way people perceive video-recording, in terms of privacy, transparency, and the notion of context. We use a model of primary and secondary contexts to analyze usage situations, highlighting newly relevant research issues.     

Respiratory Symptoms and Infections among Children in a Day-Care Center with Mold Problems

The prevalence of irritative symptoms and the incidence of respiratory infections among children in a day-care center affected by mold were compared with those in a reference day-care center. A retrospective pilot study was made in the mold-problem day-care center. Analysis of absenteeism records and a one-year follow-up study were made in both day-care centers. In the pilot study, half of the exposed 41 children had prolonged or frequent symptoms and respiratory infections. In addition, the absenteeism in the mold-problem day-care center was nearly twice as high as in the reference day-care center. After cessation of the exposure, the occurrence of respiratory symptoms decreased and no lower respiratory tract infections appeared.     

Covalent biofunctionalization of cellulose acetate with thermostable chimeric avidin

A stable, bioactive cellulose acetate (CA) surface was developed by functionalizing the surface with highly thermostable avidin form. The CA films were first functionalized with a mixture of 3-aminopropyltrimethoxysilane and tetraethoxysilane to introduce free amino groups onto the surface of CA films. Free amino groups were functionalized with glutaraldehyde to obtain an activated surface for covalent biomolecule immobilization. A genetically engineered, high-affinity biotin-binding protein chimeric avidin, ChiAVD(I117Y), was used for biofunctionalization of the surface. The chimeric avidin protein has an increased stability in chemically harsh conditions and at high temperature when compared to wt (strept)avidin. The biological activity, i.e., biotin-binding capacity, of the immobilized protein was probed by [(3)H]-biotin. The activity of the chimeric avidin on functionalized CA films was fully retained over the three months' study period. The biotin-binding capacity of the immobilized chimeric avidin was compared to that of immobilized streptavidin, chicken avidin, and rhizavidin and significant differences between proteins were detected. The developed material offers a valuable platform for the development of inexpensive in vitro diagnostics and also supports biosensing applications that are required to operate under demanding conditions.