Structure of CdTe/ZnTe superlattices

The structure of CdTe/ZnTe superlattices has been analyzed through θ/2θ x‐ray diffraction, photoluminescence, and in situ reflection high‐energy electron diffraction (RHEED) measurements. Samples are found to break away from Cd_(x)Zn_(1−x)Te buffer layers as a consequence of the 6% lattice mismatch in this system. However, defect densities in these superlattices are seen to drop dramatically away from the buffer layer interface, accounting for the intense photoluminescence and high‐average strain fields seen in each of our samples. Observed variations in residual strains suggest that growth conditions play a role in forming misfit defects. This could explain discrepancies with calculated values of critical thickness based on models which neglect growth conditions. Photoluminescence spectra reveal that layer‐to‐layer growth proceeded with single monolayer uniformity, suggesting highly reproducible growth. Our results give hope for relatively defect‐free Cd_(x)Zn_(1−x)Te/Cd_(y)Zn_(1−y)Te superlattices with the potential for applications to optoelectronics offered by intense visible light emitters

Electrical determination of the valence-band discontinuity in HgTe-CdTe heterojunctions

Current-voltage behavior is studied experimentally in a Hg0.78Cd0.22Te-CdTe-Hg0.78Cd0.22Te heterostructure grown by molecular beam epitaxy. At temperatures above 160 K, energy-band diagrams suggest that the dominant low-bias current is thermionic hole emission across the CdTe barrier layer. This interpretation yields a direct determination of 390±75 meV for the HgTe-CdTe valence-band discontinuity at 300 K. Similar analyses of current-voltage data taken at 190–300 K suggest that the valence-band offset decreases at low temperatures in this heterojunction

Voltage controlled terahertz transmission through GaN quantum wells

We report measurements of radiation transmission in the 0.220--0.325 THz frequency domain through GaN quantum wells grown on sapphire substrates at room and low temperatures. A significant enhancement of the transmitted beam intensity with the applied voltage on the devices under test is found. For a deeper understanding of the physical phenomena involved, these results are compared with a phenomenological theory of light transmission under electric bias relating the transmission enhancement to changes in the differential mobility of the two-dimensional electron gas

Einsatz bioanalytischer Systeme bei der industriellen Produktion von Pharmaaminosäuren

Aminosäuren finden in den verschiedensten Bereichen vielfältigen Einsatz. Hauptanwendungsgebiete sind die Nahrungsmittel- (50%), Futtermittel (30%)- und pharmazeutische (20%) Industrie. In der pharmazeutischen Industrie werden Aminosäuren höchster Reinheit benötigt. Ein sehr wichtiges Beispiel ist die Verwendung für prä- oder postoperative parenterale Ernährung. In der Kosmetikindustrie dienen Aminosäuren als Ausgangssubstanzen für die Herstellung hochwertiger Hautcremes. Für die Gewinnung von Aminosäuren stehen diverse großtechnische Verfahren zur Verfügung: die Extraktion aus nachwachsenden Rohstoffen, die fermentative Gewinnung, die chemische Synthese und die Biotransformation. Über diese Verfahren wird eine geschätzte Jahresproduktion von weltweit ca. 3. Mrd. Tonnen hergestellt. Bei der AMINO GmbH werden Aminosäuren für den pharmazeutischen Markt aus nachwachsenden Rohstoffen wie Zuckerrübenmelasse über chromatographische Verfahren und Biotransformationen (enzymatische Katalyse) gewonnen. Hierbei ist eine On-line-Prozesskontrolle unabdingbar. Durch die optimierte Kontrolle und Führung des Bioprozesses können Ressourcen eingespart werden. Daraus ergeben sich direkt Umweltentlastungen und Kostenersparnisse. Mit den bisher erzielten Ergebnissen kann eine 20% höhere Produktkonzentration erreicht werden. Dieses entspricht – gerechnet auf die nachfolgenden Aufarbeitungsschritte – einer Ersparnis von 200 bis 300 t Dampf pro Jahr (20% der Produkt spezifischen Energiekosten). Ebenfalls einsparen lassen sich bis zu 2000 m3 Abwasser (entsprechend 0,4 t COD) pro Jahr. Letztendlich ist es das Ziel mit Hilfe der bioanalytischen Verfahren pro Jahr 3,5 t Serin und 0,5 t Indol durch eine 30% höhere Produktausbeute einsparen zu können. Es zeigt sich somit, dass der Einsatz moderner bioanalytischer Verfahren wie der 2-D-Fluoreszenzspektroskopie durchaus zu einer Verbesserung der ökonomischen als auch der ökologischen Faktoren eines industriellen Prozesses führen kann

Can pain be self-managed?:Pain change in vulnerable participants to a health education programme

Chronic pain exerts a significant impact on the quality of life, giving rise to both physical and psycho-social vulnerabilities. It not only leads to direct costs associated with treatments, but also results in indirect costs due to the reduced productivity of affected individuals. Chronic conditions can be improved by reducing modifiable risk factors. Various educational programs, including the Chronic Disease Self-Management Programme (CDSMP), have demonstrated the advantages of enhancing patient empowerment and health literacy. Nevertheless, their efficacy in addressing pain symptoms has received limited attention, especially concerning vulnerable populations. This research aims to assess the effectiveness of the CDSMP in alleviating pain among socio-economically vulnerable participants with chronic conditions. By accounting for a wide range of variables, and using data from the EFFICHRONIC project (EU health programme), we investigated the changes in pain levels after the intervention, among 1070 participants from five European countries. Our analyses revealed a significant reduction in pain following the intervention. This finding supports the notion that training programs can effectively ameliorate pain and alleviate its impact on the quality of life, particularly in vulnerable populations. Younger participants, as well as those with higher education levels and individuals experiencing higher levels of pain at baseline, were more likely to experience a reduction in their pain levels. These findings underscore the importance of recognising the social determinants of health. The study was registered at ClinicalTrials.gov (ISRCTN70517103).</p

Raman scattering determination of strain in CdTe/ZnTe superlattices

The strain configuration in CdTe/ZnTe strained-layer superlattices has been measured by Raman scattering near resonance. The ZnTe-like longitudinal optical phonon energy in the superlattice is significantly shifted from the bulk value to lower energies and the shift increases with increasing superlattice CdTe fraction. The observed shifts agree with calculations of strain shifts based on a free-standing strain distribution

Middleborns disadvantaged? testing birth-order effects on fitness in pre-industrial finns

Parental investment is a limited resource for which offspring compete in order to increase their own survival and reproductive success. However, parents might be selected to influence the outcome of sibling competition through differential investment. While evidence for this is widespread in egg-laying species, whether or not this may also be the case in viviparous species is more difficult to determine. We use pre-industrial Finns as our model system and an equal investment model as our null hypothesis, which predicts that (all else being equal) middleborns should be disadvantaged through competition. We found no overall evidence to suggest that middleborns in a family are disadvantaged in terms of their survival, age at first reproduction or lifetime reproductive success. However, when considering birth-order only among same-sexed siblings, first-, middle-and lastborn sons significantly differed in the number of offspring they were able to rear to adulthood, although there was no similar effect among females. Middleborn sons appeared to produce significantly less offspring than first-or lastborn sons, but they did not significantly differ from lastborn sons in the number of offspring reared to adulthood. Our results thus show that taking sex differences into account is important when modelling birth-order effects. We found clear evidence of firstborn sons being advantaged over other sons in the family, and over firstborn daughters. Therefore, our results suggest that parents invest differentially in their offspring in order to both preferentially favour particular offspring or reduce offspring inequalities arising from sibling competition

Melanesian and Asian origins of Polynesians: mtDNA and Y chromosome gradients across the Pacific

The human settlement of the Pacific Islands represents one of the most recent major migration events of mankind. Polynesians originated in Asia according to linguistic evidence or in Melanesia according to archaeological evidence. To shed light on the genetic origins of Polynesians, we investigated over 400 Polynesians from 8 island groups, in comparison with over 900 individuals from potential parental populations of Melanesia, Southeast and East Asia, and Australia, by means of Y chromosome (NRY) and mitochondrial DNA (mtDNA) markers. Overall, we classified 94.1% of Polynesian Y chromosomes and 99.8% of Polynesian mtDNAs as of either Melanesian (NRY-DNA: 65.8%, mtDNA: 6%) or Asian (NRY-DNA: 28.3%, mtDNA: 93.8%) origin, suggesting a dual genetic origin of Polynesians in agreement with the "Slow Boat" hypothesis. Our data suggest a pronounced admixture bias in Polynesians toward more Melanesian men than women, perhaps as a result of matrilocal residence in the ancestral Polynesian society. Although dating methods are consistent with somewhat similar entries of NRY/mtDNA haplogroups into Polynesia, haplotype sharing suggests an earlier appearance of Melanesian haplogroups than those from Asia. Surprisingly, we identified gradients in the frequency distribution of some NRY/mtDNA haplogroups across Polynesia and a gradual west-to-east decrease of overall NRY/mtDNA diversity, not only providing evidence for a west-to-east direction of Polynesian settlements but also suggesting that Pacific voyaging was regular rather than haphazard. We also demonstrate that Fiji played a pivotal role in the history of Polynesia: humans probably first migrated to Fiji, and subsequent settlement of Polynesia probably came from Fiji