The dipeptide H-Aib-l-Ala-OH ligand in copper(II) chemistry: Variation of product identity as a function of pH

A systematic investigation of the influence of “pH” on the product identity from the Cu^II/H-Aib-l-Ala-OH (LH) reaction system is described, where H-Aib-l-Ala-OH is α-aminoisobutyryl-l-alanine. The pH variation has led to the synthesis of two discrete complexes, the structures of which have been determined by single-crystal X-ray crystallography. The “low pH” complex {[CuClL](H₂O)_2.5}_n (1) is a 3D coordination polymer, in which the dipeptide monoanion L⁻ behaves as a η¹:η¹:η¹:μ₂ ligand binding one Cu^II atom through its amino nitrogen and neutral peptide oxygen, and an adjacent Cu^II atom through one of its carboxylate oxygen. The “higher pH” complex {[Cu(H₋₁L)(EtOH)](EtOH)}_n (2) is a chain (1D) compound, in which the dipeptide dianion H₋₁L²⁻ uses its amino nitrogen, deprotonated peptide nitrogen and both carboxylate oxygens to bridge two metal centres.     

Diagnosing and acting on student affect: the tutor’s perspective

In this paper we explore human tutors’ inferences in relation to learners’ affective states and the relationship between those inferences and the actions that tutors take as their consequence. At the core of the investigations presented in this paper lie fundamental questions associated with the role of affective considerations in computer-mediated educational interactions. Theory of linguistic politeness is used as the basis for determining the contextual factors relevant to human tutors’s actions, with special attention being dedicated to learner affective states. A study was designed to determine what affective states of the learners are relevant to tutoring mathematics and to identify the mechanisms used by tutors to predict such states. Logs of tutor-student dialogues were recorded along with contextual factors taken into consideration by tutors in relation to their specific tutorial dialogue moves. The logs were annotated in order to determine the types and range of student and tutor actions. Machine learning techniques were then applied to those actions to predict the values of three factors: student confidence, interest and effort. Whilst due to limited size and sparsity of data the results are not conclusive, they are very valuable as the basis for empirically derived hypotheses to be tested in further studies. The potential implications of the hypotheses, if they were confirmed by further studies, are discussed in relation to the impact of tutor’s ability to diagnose student affect on the nature of computer-mediated tutorial interactions.     

Integration of carbon nanotubes as hole transport electrode in polymer/fullerene bulk heterojunction solar cells

Transparent and conductive single-walled carbon nanotube (SWNT) thin films were fabricated onto glass substrates and their optical and electrical properties were evaluated. Particular attention was given to the dependence of the conductivity and optical transparency on the thickness of the films. Furthermore, the SWNT thin films were integrated in organic photovoltaic devices as the hole transport electrode. The best photovoltaic performance was observed for the devices utilizing 80 nm SWNT films with a sheet resistance of 362 Ω/sq, and a transmittance of 64% at 520 nm. The experiments reveal that SWNTs films can be used as transparent electrodes for efficient, flexible organic photovoltaic devices.     

Three-dimensional BEM for transient elastodynamics based on the velocity reciprocal theorem

The conventional way for formulating a time domain boundary element method (TD-BEM) in linear elastodynamics is to utilize Graffi's reciprocal theorem. This theorem may either be the starting point in formulating a numerical methodology or the endpoint, if one starts directly from the governing equations of motion and follows various manipulations. The literature abounds with evidence of serious instability problems that accompany these formulations. Thus, research effort has been devoted on reducing this undesirable behavior. In this paper, we utilize a reciprocal theorem that relates velocities and tractions of two different elastodynamic states of the same body, in order to establish a well behaved TD-BEM formulation for 3D transient problems. It is shown that regarding stability, this straightforward formulation is capable of not only reducing instabilities compared to the conventional formulation, but also seems to eliminate the “intermittent” as well as the “sudden” instability problem.     

EDM electrode manufacture using rapid tooling: a review

Electrical discharge machining (EDM) is a non-conventional process for the manufacture of complex or hard material parts that are difficult to machine by conventional machining processes. During EDM, the electrode shape is mirrored in the workpiece. As a result, problems are transferred on the electrode manufacturing process. Rapid tooling (RT) is a new technology which uses rapid prototyping (RP) models to reduce the time and cost of tool manufacture. The various methods of manufacturing RT electrodes, with respect to different materials and the incorporated supplementary processes, are classified in the present work. Recent international research work on RT electrodes is reviewed and the results on the performance of RT electrodes are tabulated.     

Pretreatment with aspirin and ticlopidine confers lower thrombogenic potential of radiofrequency catheter ablation

One male of a group of seven Pacific white-sided dolphins (Lagenorhynchus obliquidens) died after a brief period of nonspecific clinical signs. Four beluga whales (Delphinapterus leucas) and four harbor seals (Phoca vitulina) were managed in the same water system. Gross examination of the dolphin revealed only moderately enlarged mesenteric lymph nodes. Histopathology revealed small to massive numbers of gram-positive bacilli, usually intravascular, in all tissues. Bacteria were both extracellular and present in macrophages, monocytes, and neutrophils. Aerobic bacterial culture of lung, liver, kidney, and spleen yielded pure cultures of Erysipelothrix rhusiopathiae. Based on clinical course, histopathology, and bacteriology, a diagnosis of acute erysipelas septicemia was made. None of the other cetaceans or pinnipeds exhibited clinical signs.     

Functionalized Graphene as an Electron‐Cascade Acceptor for Air‐Processed Organic Ternary Solar Cells

Functionalized graphene nanoflakes (GNFs) are used as an electron‐cascade acceptor material in air‐processed organic ternary bulk heterojunction solar cells. The functionalization is realized via the attachment of the ethylenedinitrobenzoyl (EDNB) molecule to the GNFs. Simulation and experimental results show that such nanoscale modification greatly influences the density of states near the Fermi level. Consequently, the GNF‐EDNB blend presents favorable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels to function as a bridge structure between the poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] (PCDTBT) and the [6,6]‐phenyl‐C71‐butyric‐acid‐methyl‐ester (PC₇₁BM). The improved exciton dissociation and charge transport are associated with the better energy level alignment of the ternary blend and the high electrical conductivity of the GNFs, which act as additional electron transport channels within the photoactive layer. The resulting PCDTBT/GNF‐EDNB/PC₇₁BM ternary organic solar cells, fabricated entirely under ambient conditions, exhibit an average power conversion efficiency enhancement of ≈18% as compared with the binary blend PCDTBT/PC₇₁BM.     

Reduced Graphene Oxide Micromesh Electrodes for Large Area,Flexible, Organic Photovoltaic Devices

A laser‐based patterning technique—compatible with flexible, temperature‐sensitive substrates—for the production of large area reduced graphene oxide micromesh (rGOMM) electrodes is presented. The mesh patterning can be accurately controlled in order to significantly enhance the electrode transparency, with a subsequent slight increase in the sheet resistance, and therefore improve the tradeoff between transparency and conductivity of reduced graphene oxide (rGO) layers. In particular, rGO films with an initial transparency of ≈20% are patterned, resulting in rGOMMs films with a ≈59% transmittance and a sheet resistance of ≈565 Ω sq^?1, that is significantly lower than the resistance of ≈780 Ω sq^?1, exhibited by the pristine rGO films at the same transparency. As a proof‐of‐concept application, rGOMMs are used as the transparent electrodes in flexible organic photovoltaic (OPV) devices, achieving power conversion efficiency of 3.05%, the highest ever reported for flexible OPV devices incorporating solution‐processed graphene‐based electrodes. The controllable and highly reproducible laser‐induced patterning of rGO hold enormous promise for both rigid and flexible large‐scale organic electronic devices, eliminating the lag between graphene‐based and indium–tin oxide electrodes, while providing conductivity and transparency tunability for next generation flexible electronics.     

Maastricht essential fatty acid birth cohort

The Maastricht Essential Fatty Acid Birth cohort (MEFAB) was established in 1989 to study the changes in fatty acid concentration during pregnancy and how this related to the fatty acid concentrations of the neonate. The original sample contains data of 1203 subjects. Some participants whom participated in the original MEFAB study also participated in follow‐up studies at age 4, 7 or 12; 41%, 52% and 35% of eligible participants, respectively. Collected data include maternal fatty acid concentrations at multiple points during pregnancy and at birth and at age 7 for the child, but also anthropometric measurements during development, assessments of cognitive development, asthma, atopy and cardiovascular risk factors. Data of MEFAB have been used in 37 articles in peer‐reviewed journals and 4 doctoral theses have been completed. Data of MEFAB is upon request available for new research questions.