Structure-activity relationship studies on the immune stimulatory effects of base-modified CpG toll-like receptor 9 agonists

Synthetic oligodeoxynucleotides containing unmethylated deoxycytidylyl-deoxyguanosine dinucleotide (CpG) motifs are able to stimulate potent immune responses through a signaling pathway involving Toll-like receptor 9 (TLR9). We have investigated the structure-activity relationship (SAR) of base-modified CpG oligonucleotides with TLR9 by measuring TLR9 activation by 20-mer oligonucleotides having just a single human recognition motif (5'-GTCGTT-3') in functional cell-based TLR9 assays. Substitution of guanine by hypoxanthine and 6-thioguanine resulted in activity similar to the unmodified parent molecule, whereas purine, 2-aminopurine, 2,6-diaminopurine, and 8-oxo-7,8-dihydroguanine substitution resulted in approximately 40-60 % reduction in activity, and 7-deazaguanine substitution led to the strongest (80 %) reduction in TLR9 stimulation. Furthermore, none of the investigated modifications at C5 and N4 of cytosine were well tolerated with respect to human TLR9 stimulation. Our results are compatible with a SAR model in which guanine is recognized by the Hoogsteen site, and C5 is most critical for recognition of cytosine. In addition, we found significant species-specific differences between human and murine TLR9 recognition, which demonstrates the importance of choosing appropriate assay systems for SAR studies.     

Effect of gadolinium ions on the structure and magnetic properties of zinc-borate glasses and glass ceramics

X-ray diffraction (XRD), electron paramagnetic resonance (EPR), and magnetic susceptibility measurements have been employed to investigate the samples from the (Gd₂O₃) _x ·(B₂O₃)_(60−x)·(ZnO)₄₀ (0 ≤ x ≤ 20 mol%) system. The XRD pattern for the prepared samples shows that the vitreous phase is present only for x ≤ 15 mol%. For the samples containing 20 mol% Gd₂O₃ the presence of a unique crystalline phase, GdBO₃, embedded in a vitreous matrix was evidenced. In this case the XRD patterns show the presence of nanometer sized crystals (64 nm) in a glassy matrix. The EPR spectra of the studied samples exhibit three important features with effective g-values of ≈6, 2.8, 2.0 and a weaker feature at g ≈ 4.8. For low Gd₂O₃ contents (x < 3 mol%), the EPR spectra have the typical ‘‘U’’-type shape. For higher contents of Gd₂O₃ (x ≥ 3 mol%), the spectral features are broadened and finally are dominated by a single broad absorption line located at g ≈ 2.0. This broad EPR line is associated to the Gd³⁺ ions present predominantly as clustered species. Magnetic susceptibility data show that for x > 1 mol% the Gd³⁺ ions are present not only as isolated species but also as species coupled through antiferromagnetic exchange interactions.     

CuInS2-Poly(3-(ethyl-4-butanoate)thiophene) nanocomposite solar cells: Preparation by an in situ formation route, performance and stability issues

In this contribution we present an in situ method for the preparation of CuInS₂-poly(3-(ethyl-4-butanoate)thiophene) (P3EBT) nanocomposite layers and their application in nanocomposite solar cells. A precursor solution containing copper and indium salts, thiourea and the conjugated polymer was prepared in pyridine, which was coated onto glass/ITO substrates followed by a heating step at 180 °C. The heating step induced the formation of the CuInS₂ nanoparticles homogeneously dispersed in the conjugated polymer matrix. The formation of the nanocomposite was investigated in situ by X-ray scattering techniques and TEM methods showing that nano-scaled CuInS₂ was formed. By addition of small amounts of zinc salt to the precursor solution, zinc containing CuInS₂ (ZCIS) was formed. ZCIS-P3EBT active layers exhibited higher V_OC than CuInS₂-P3EBT layers and showed efficiencies of about 0.4%. Additionally the stability of the solar cells was tested over a time scale of 172 h.     

Towards modeling gadolinium-lead-borate glasses

Infrared spectra of gadolinium-lead-borate glasses of the xGd₂O₃·(100 − x)[3B₂O₃·PbO] system, where x = 0, 5, 10, 15, 25, 35 and 50 mol.%, have been recorded to explore the role of content of gadolinium ions behaving as glass modifier.The FTIR spectroscopy data for the xGd₂O₃·(1 − x)[3B₂O₃·PbO] glasses show the structural role of lead ions as a network-formers and of the gadolinium ions network modifiers. Adding of the rare earth ion up to 35 mol.% into the glass matrix, the IR bands characteristic to the studied glasses become sharper and more pronounced.Structural changes, as recognized by analyzing band shapes of IR spectra, revealed that Gd₂O₃ causes a change from the continuous borate network to the continuous lead-borate network interconnected through Pb-O-B and B-O-B bridges and the transformation of some tetrahedral [BO₄] units into trigonal [BO₃] units. Then, gadolinium ions have affinity towards [BO₃] structural units which contain non-bridging oxygens necessary for the charge compensation because the more electronegative [BO₃] structural units were implied in the formation of B-O-Gd bonds and the transformation of glass network into a glass ceramic.We propose a possible structural model of building blocks for the formation of continuous random 3B₂O₃·PbO network glass used by density functional theory (DFT) calculations.DFT calculations show that lead atoms occupy three different sites in the proposed model. The first is coordinated with six oxygen atoms forming distorted octahedral geometries. The second lead atom has an octahedral oxygen environment and the five longer Pb-O bonds are considered as participating in the metal coordination scheme. The third lead atom has ionic character. In agreement with the results offered by the experimental FTIR data, the theoretical IR data confirm that our proposed structure is highly possible.     

Effect of the introduction of vanadium pentaoxide in phospho-tellurite glasses containing gadolinium ions

A range of phospho-tellurite glasses containing gadolinium was prepared and infrared absorption spectra were measured. Structural changes, as recognized by analyzing band shapes of IR spectra, revealed that Gd₂O₃ causes a higher extent of network polymerization as far as x ≤ 15 mol% because the conversion of [TeO₄] to [TeO₃] structural units is supported by the increase of metaphosphate structural groups. While for x between 20 and 30 mol% Gd₂O₃ show some drastic structural modifications which lead to the increase in the glass fragility. Thus the addition of V₂O₅ resulted in gradual depolymerization of the phosphate chains and formation of short phosphate units, which are linked to vanadium through P–O–V bonds. The formation of P–O–V bonds increases the cross-link between the phosphate chains and the bending mode of Te–O–Te or O–Te–O linkages.     

Tip of the tongue selectivity and motor learning in the palatal area

This study assessed the ability of the tongue tip to accurately select intraoral targets embedded in an upper palatal tongue-computer interface, using 18 able-bodied volunteers. Four performance measures, based on modifications to Fitts's Law, were determined for three different tongue-computer interface layouts. The layouts differed with respect to number and location of the targets in the palatal interface. Assessment of intraoral target selection speed and accuracy revealed that performance was indeed dependent on the location and distance between the targets. Performances were faster and more accurate for targets located farther away from the base of the tongue in comparison to posterior and medial targets. A regression model was built, which predicted intraoral target selection time based on target location and movement amplitude better than the predicted by using a standard Fitts's Law model. A 30% improvement in the speed and accuracy over three daily practice sessions of 30 min emphasizes the remarkable motor learning abilities of the tongue musculature and provides further evidence that the tongue is useful for operating computer-interface technologies.     

New super-orthogonal space-time trellis codes using differential M-PSK for noncoherent mobile communication systems with two transmit antennas

In this paper, we develop super-orthogonal space-time trellis codes (SOSTTCs) using differential binary phase-shift keying, quadriphase-shift keying and eight-phase shift keying for noncoherent communication systems with two transmit antennas without channel state information at the receiver. Based on a differential encoding scheme proposed by Tarokh and Jafarkhani, we propose a new decoding algorithm with reduced decoding complexity. To evaluate the performance of the SOSTTCs by way of computer simulations, a geometric two-ring channel model is employed throughout. The simulation results show that the new decoding algorithm has the same decoding performance compared with the traditional decoding strategy, while it reduces significantly the overall computing complexity. As expected the system performance depends greatly on the antenna spacing and on the angular spread of the incoming waves. For fair comparison, we also design SOSTTCs for coherent detection of the same complexity as those demonstrated for the noncoherent case. As in the case of classical single antenna transmission systems, the coherent scheme outperforms the differential one by approximately 3 dB for SOSTTCs as well.     

Note on the effect of thermal radiation in the linearized Rosseland approximation on the heat transfer characteristics of various boundary layer flows

In the latter years the title problem has been examined in a large number of research papers. The present Note emphasizes, however, that the effect of thermal radiation in the linearized Rosseland approximation is quite trivial, both physically and computationally. Namely, it always reduces to a simple rescaling of the Prandtl number by a factor involving the radiation parameter. This implies that a comprehensive study of the Prandtl-number dependence without thermal radiation effects represents per se a detailed study of the radiation effects, too. In other words, the solution of the radiation problem for optically thick media in the linearized Rosseland approximation does not require any additional numerical or analytical effort compared to the same problem without radiation, making in this respect dozens of papers superfluous.     

Structural studies on iron-tellurite glasses prepared by sol-gel method

In this study, we report structural properties of the iron-tellurite glasses obtained using the sol-gel synthesis. The samples were characterized by X-ray diffraction, FTIR, UV-vis and EPR spectroscopy. Our results indicate dominant presence of iron ions in the trivalent state and the existence some Fe²⁺ ions. The analysis of the IR spectra indicates a gradual transformation of iron ions from tetrahedral into octahedral sites when the concentration of Fe(NO₃)₃ is increased beyond 0.64 mol%. EPR studies show that the increase of Fe(NO₃)₃ content in the host matrix induces the growth of the number of effective g values. This can be explained considering that the orbitals of O²⁻ ion with a large spin-orbit interaction constant will interact with the 3d orbital of Fe³⁺ ion bonded to this O²⁻ ion, thus leading to appearance of an orbital angular momentum which contributes to the magnetic moment of Fe³⁺ ion. A strong dipolar interaction, which is more predominant in a glass with higher content of Fe(NO₃)₃, causing a localized magnetic field along the site of the Fe³⁺ ions and the increase the effective g values.