Progress in emitter wrap-through solar cell fabrication on boron doped Czochralski-grown silicon

We report on RISE-EWT (Rear Interdigitated Single Evaporation-Emitter Wrap-Through) solar cells on full area (12.5×12.5 cm²) pseudo square boron doped Czochralski-grown silicon wafers. We investigate the main efficiency optimisation factors of these cells by investigating the dependence of RISE-EWT cell parameters on the base dopant concentration N_A. We furthermore detail the effects of large feature sizes in base and emitter regions at the rear of the solar cell and investigate these effects with particular attention to the edge regions. EWT solar cells typically exhibit rather low fill factors. However, our results show that the improved fill factors can be achieved by increasing N_A, which in return leads to optimised efficiency values. For our RISE-EWT solar cells made from boron doped Cz-Si wafers, this benefit is maintained even after light-induced degradation. Our investigation of edge area related effects shows the importance of proper cell design in these areas, leading to a further 2.8% absolute improvement in the fill factor. Combining increased base dopant concentration with optimised edge design, we achieve 19.0% efficiency on (12.5×12.5 cm²) boron doped Cz silicon wafers before light-induced degradation, resulting in 18.1% efficiency in the light-degraded state.     

Biomechanical aspects of occupational neck postures during dental work

A typical occupational risk factor for developing neck symptoms is prolonged flexion of the cervical spine. The present aim was to determine joint moments and muscle activity of the neck during forward flexion of the cervical spine to evaluate the load in the neck region. Three dimensional video (3-D) and surface electromyography (EMG) from the splenius muscles were recorded in two common work postures. Using a 3-D static link segment model, moments at the atlanto-occipital (A-O) joint and the seventh cervical-first thoracal (C7-T1) joint were estimated. Maximal extension moments were estimated from maximal neck extension strength. Extension moments at the C7-T1 joint were significantly higher for a highly flexed position (45% of max) compared to a moderately flexed position (32% of max), but remained unchanged at the A-O joint (40% of max). The mean RMS amplitude was 9% of maximal EMG in both positions (no bilateral differences). This difference between mechanical load and muscle load indicates that EMG may seriously underestimate the total loads of the tissue. Lateral flexion influenced the lateral flexion moment while rotation did not influence the rotation moment. The study demonstrates the importance of quantification of joint loads in occupational risk assessment of the neck.

Relevance to industry

3-D biomechanical calculations provide information on the mechanical load during work. Because EMG may underestimate total tissue load, calculations of joint moments in combination with information on muscle activity and strength are necessary to estimate different tissue loading of significance for overall risk identification.     

Signal strength versus cuff length in nerve cuff electrode recordings

When a nerve cuff electrode is used for the recording of signals from peripheral nerves, cuff dimensions have to be chosen. Traditionally, the peak-to-peak amplitude of the single-fiber action potential (SFAP) is optimized through the choice of cuff diameter and cuff length. In this paper, the dependency of the root-mean-square (RMS) value of the nerve signal on the cuff dimensions was studied and compared with the peak-to-peak value of the SFAP. A simple approximation for signal optimization by cuff dimensioning is suggested. The results were obtained from modeled SFAPs and from the electroneurogram (ENG) created by superimposed SFAPs, obtained from an inhomogeneous volume conductor model. The results show that the RMS value of the nerve signal is considerably more sensitive to the cuff length than the SFAP peak-to-peak amplitude, and that the RMS of the ENG is a linear function of the fiber diameter.     

Affinity and Specificity for Binding to Glycosaminoglycans Can Be Tuned by Adapting Peptide Length and Sequence

Although glycosaminoglycan (GAG)–protein interactions are important in many physiological and pathological processes, the structural requirements for binding are poorly defined. Starting with GAG-binding peptide CXCL9(74-103), peptides were designed to elucidate the contribution to the GAG-binding affinity of different: (1) GAG-binding motifs (i.e., BBXB and BBBXXB); (2) amino acids in GAG-binding motifs and linker sequences; and (3) numbers of GAG-binding motifs. The affinity of eight chemically synthesized peptides for various GAGs was determined by isothermal fluorescence titration (IFT). Moreover, the binding of peptides to cellular GAGs on Chinese hamster ovary (CHO) cells was assessed using flow cytometry with and without soluble GAGs. The repetition of GAG-binding motifs in the peptides contributed to a higher affinity for heparan sulfate (HS) in the IFT measurements. Furthermore, the presence of Gln residues in both GAG-binding motifs and linker sequences increased the affinity of trimer peptides for low-molecular-weight heparin (LMWH), partially desulfated (ds)LMWH and HS, but not for hyaluronic acid. In addition, the peptides bound to cellular GAGs with differential affinity, and the addition of soluble HS or heparin reduced the binding of CXCL9(74-103) to cellular GAGs. These results indicate that the affinity and specificity of peptides for GAGs can be tuned by adapting their amino acid sequence and their number of GAG-binding motifs.     

Efficient solutions for Mastermind using genetic algorithms

We present a new genetic algorithm for playing the game of Mastermind. The algorithm requires low run-times and results in a low expected number of guesses. Its performance is comparable to that of other meta-heuristics for the standard setting with four positions and six colors, while it outperforms the existing algorithms when more colors and positions are examined. The central idea underlying the algorithm is the creation of a large set of eligible guesses collected throughout the different generations of the genetic algorithm, the quality of each of which is subsequently determined based on a comparison with a selection of elements of the set.     

Modern Meal Patterns: Tensions Between Bodily Needs and the Organization of Time and Space

This article argues that a sound understanding of eating must include analyses of the relation between the experienced body and different dimensions of eating patterns, such as the rhythm of eating, the quality of the meal, and its social context. In a qualitative interview study carried out in Copenhagen, Denmark, the relationship between eating habits and immediate bodily experiences of hunger, satiety, and appetite was investigated through open-ended, in-depth interviews with 20 individuals representing a variety of socio-economic backgrounds. In everyday life, most interviewees had problems accommodating what they considered to be an ideal meal pattern, i.e. an eating routine meeting their cultural and bodily needs simultaneously. We argue that the prevailing cultural model of meal patterns is detached from, and in conflict with, modern social organization of time and space. The individual body has become the place where conflicting structures and demands in society are experienced; it is also the place where these conflicts are supposed to be solved.     

Artefact reduction with alternative cuff configurations

In nerve cuff electrode recordings of neural signals, the pick-up of interfering signals can be reduced by choosing appropriate cuff configurations. In the traditionally used tripolar configuration, short circuiting of the end electrodes is expected to reduce the field inside the cuff from interfering signals. A model study suggests that moving the end electrodes toward the center of the cuff reduces the pick-up of interfering signals. In this paper, these properties are studied in more detail using a rabbit model. In addition, a new cuff configuration is suggested, which has an additional set of short circuited end electrodes. The total improvement of signal-to-noise ratio in the new configuration as compared with the traditionally used tripolar configuration was 73% for muscle signals and 127% for the stimulus pulse.     

One-Sided Chronic Intervillositis of Unknown Etiology in Dizygotic Twins: A Description of 3 Cases

Chronic intervillositis of unknown etiology (CIUE) is a rare, poorly understood, histopathological diagnosis of the placenta that is frequently accompanied by adverse pregnancy outcomes including miscarriage, fetal growth restriction, and intrauterine fetal death. CIUE is thought to have an immunologically driven pathophysiology and may be related to human leukocyte antigen mismatches between the mother and the fetus. Dizygotic twins with one-sided CIUE provide an interesting context to study the influence of immunogenetic differences in such cases. The main immune-cell subsets were investigated using immunohistochemistry. We identified three dizygotic twin pregnancies in which CIUE was present in only one of the two placentas. Two of the pregnancies ended in term delivery and one ended in preterm delivery. Presence of CIUE was correlated with lower placental weight and lower birthweight. Relative number of CD68, CD56, CD20, and CD3 positive cells were comparable between co-twins. The presence of one-sided CIUE in dizygotic twin pregnancy was associated with selective growth restriction in the affected twin. This suggests a unique fetal immunogenetic contribution to the pathogenesis of CIUE. Further study of dizygotic and monozygotic placentas affected by CIUE could identify new insights into its pathophysiology and into the field of reproductive immunology.     

Combining confinement and NO calcination to arrive at highly dispersed supported nickel and cobalt oxide catalysts with a tunable particle size

Control over the size and size distribution of supported nanoparticles is key to their efficient use in catalysis. In the preparation of nanoparticles by impregnation using nitrate precursors, the support pore diameter can be used to influence the average crystallite size. However, the particle size distributions obtained via this method are generally broad and the dispersions relatively low. Higher dispersions and narrow particle size distributions are obtained via thermal decomposition of the metal nitrate precursor in 1% (v/v) NO in Ar instead of air. Here we will show that by combining the confinement effect of ordered mesoporous silica with a decomposition step of metal nitrates in NO, silica supported nickel and cobalt oxides with a tunable particle size (2–4 nm) can be obtained at high loadings (10–20 wt%).     

Physical properties of mammary secretions in relation to chemical changes during transition from colostrum to milk

We examined the physical and chemical changes in milk during early lactation, and how these changes were affected by leaving one quarter unmilked in either the first or second milking, with the purpose of discriminating between colostrum and normal milk. Milk samples were collected from each quarter of 17 cows during the first 5 d after calving and then after about 7 d and 14d. Samples were analysed for somatic cell count (SCC), fat, protein, casein, lactose, IgG1, colour, plasmin, pH and coagulation properties. Large variations occurred in both chemical and physical properties throughout the study period. Within six milkings, the concentration of casein decreased by 60%, IgG1 by 94%, and lactose increased by 34%. At milking number 6, rennet coagulation time was lowest and curd firmness was highest. The pH increased from 6.4 to 6.7 over the period of the experiment, and the colour changed from yellow (reddish) to white. Coagulation properties and the pH fell within the range of normal milk after five milkings. Measurement of colour and density appeared to be a potential method for detection of milk unsuitable for the dairy factory. Effects of omitting one quarter in one milking differed between milk components, but seemed to be of little importance to the physical properties.