12 research outputs found
for the Synthesis of α,α‐Dialkyl‐α‐Amino Acids
No full textalpha alpha ,-Disubstituted -amino acids are central to biotechnological and biomedical chemical processes for their own sake and as substructures of biologically active molecules for diverse biomedical applications. Structurally, these compounds contain a quaternary stereocenter, which is particularly challenging for stereoselective synthesis. The pyridoxal-5-phosphate (PLP)-dependent L-serine hydroxymethyltransferase from Streptococcus thermophilus (SHMTSth; EC 2.1.2.1) was engineered to achieve the stereoselective synthesis of a broad structural variety of ,-dialkyl--amino acids. This was accomplished by the formation of quaternary stereocenters through aldol addition of the amino acids D-Ala and D-Ser to a wide acceptor scope catalyzed by the minimalist SHMTSth Y55T variant overcoming the limitation of the native enzyme for Gly. The SHMTSth Y55T variant tolerates aromatic and aliphatic aldehydes as well as hydroxy- and nitrogen-containing aldehydes as acceptors
Guarantees of origin for electricity production
No full textU radu napravljen je kratki pregled električne energije, njezinih izvora te posebno su naglašeni obnovljivi izvori energije iz kojih dobivamo zelenu energiju. U različitim grafičkim prikazima dani su pregledi proizvodnje, ekološki utjecaji i prednosti te nedostaci. Obrađene su najznačajnije udruge i dokumenti usko vezani uz sustave jamstva podrijetla električne energije te je prikazano stanje u Republici Hrvatskoj preko udruge HROTE i HEP-ovog programa ZelEn.This work provides a brief overview of the electrical energy, its sources and emphasis on renewable energy sources from which green energy is generated. Overview of generation, environmental impacts, advantages and shortcomings is given throughout different diagrams. The most important associations and documents related to the Guarantee of Origin were processed and the situation in the Republic of Croatia was presented through the HROTE association and HEP ZelEn program
Ideal scale-up of microreactor
No full textMikroreaktorji nudijo izboljšan prenos toplote in snovi, večjo varnost in bolj zelen pristop za pridobivanje številnih kemijskih produktov. Poleg tega nudijo lažje obratovanje in zahtevajo manj stroškov, povezanih s tem. V njih lahko dosežemo različne tokovne pogoje in izdelani so lahko iz raznolikih materialov. Za večje proizvode se jih pogosto uporabi več v seriji ali pa se izvede povečevalni efekt, katerega učinkovitost se preveri s pomočjo dimenzijske analize ali s pomočjo modela. V tej magistrski nalogi sem uporabil mrežno Boltzmannovo metodo z globinskim povprečenjem, da sem pripravil psevdodvodimenzionalen model mikroreaktorja realnih dimenzij z zapleteno vstopno geometrijo. Rezultate modela sem preveril v laboratoriju, kjer sem spremljal redčenje sledilca (vodne raztopine rdečega barvila za živila) po mikrokanalu. Ugotovil sem, da model zanesljivo oblikuje primerljive tokovne profile, vendar pa je pri samih vrednostih hitrosti prišlo do večjega odstopanja. Sklepal sem, da so za večje odstopanje krivi predvsem moj pristop merjenja v laboratoriju in težave pri analizi pridobljenega videa. Za bodočo laboratorijsko preverjanje modelov povečevalnega efekta mikroreaktorjev bi predlagal uporabo boljše snemalne opreme, sledilca temnejše barve, barve z večjim kontrastom, uporabo fluorescentnega sledilca ali pa merjenje hitrosti z mikrodelci.Microreactors produce better transport phenomena, have better safety outcomes and are a greener solution for producing a wide range of chemical compounds. They are also easier and cheaper to manage. They can accommodate a wide range of flow patterns and can be made from a large pool of materials. Numbering-up is a common way to increase their output as well as scaling-up. The effectiveness of scaling-up can be determined by a dimensional analysis or by using a model. In this work I used a lattice Boltzmann model with a depth-averaged approach to model the flow of a microreactor of real dimension. I then compared the model results with the results obtained in a lab setting by a dilution-based characterisation method, in which I measured the flow speed by sending a tracer solution (red food dye diluted in water) through the microchannel. I discovered that the model can reliably predict the flow profile, but the actual values of the flow velocity do differ by a noticeable amount. I concluded that the difference in the value of flow velocity is mainly due to my measuring approach and difficulty in analysing the resulting video. For further experimentation I suggest using better recording equipment, a darker, more contrasting or even a fluorescent tracer or perhaps by using micro image velocimetry
TUNE YOUR RESONANCE AND FIND A NEW ONE: EFFECTS OF ISOTOPIC SUBSTITUTION AND VIBRATIONAL EXCITATION IN HCNO
No full textAuthor Institution: Physikalisch Chemisches Institut, Justus-Liebig-Universit\""{a}t Giessen; Academia Istropolitana Zelen\`{a} 4, 81104, Bratislava, CSFR; Institute of Optoelectronics German Aerospace Research Est. (DLR), W-8031 Oberpfaffenhofen, Germany; Physikalisch Chemisches Institut, Justus-Liebig-Universit\""{a}t Giessen; Sektion Mathematik, Universit\""{a}t LeipzigIsotopic substitution and vibrational excitation shift the energy intervals between analogous sets of interacting states. The effects on the spectrum can be dramatic. In the case of HCNO, new information concerning a Coriolis resonance first became available through such effects. The ``tuning"" we have achieved so far involves the isotopically substituted species , and/or excitation of at least one quantum of , , or
IMPLEMENTING A RIGOROUS WEIGHTING SCHEME FOR FITTING TO ROTATIONALLY RESOLVED SPECTRAL LINE POSITIONS
No full textAuthor Institution: Physikalisch-Chemisches Institut, Justus-Liebig-Universit\""{a}t Giessen, W-6300; Physikalisch-Chemisches Institut, Academia Istropolitana Zelen\acute{a}Independent observations should be weighted according to the inverse of the squares of their uncertainties in any fitting procedure. For many types of spectroscopic experiments, uncertainties are not easy to determine. For rotationally resolved spectral data recorded digitally and presented in the form of a transmittance spectrum, we have devised a procedure which automatically determines the correct relative weights of line positions. This procedure uses a background spectrum to determine the local S/N of each line. It also considers the degree of distortion in the line shape, which becomes important for strong lines, due to Beer’s law. Our program has been implemented to supply statistical weights for data recorded with the Bruker IFS 120 H.R interferometer. Example of applications to current data, such as bands in the infrared spectrum at HCNO, will be presented
The Image of the Ural Nature in Children’s Literature of the 1930s-1950s
No full textThe article is devoted to the formation of the image of the Ural nature in children and teenagers’ literature of the 1930s–1950s. The need for youth literature that tells the growing readers about the specifics of the country’s regions led to the development of the theme of nature in the texts of the Ural authors in cognitive, pragmatic, and aesthetic aspects. Each of these aspects contributes to the formation of children’s understanding of their native region, allowing the reader to become fully acquainted with its unique characteristics. As material for the analysis the author draws upon the texts of various genres published in the Urals in the specified period, including those published in the literary and journalistic magazine «Uralsky Sledopyt» [«Ural Pathfinder»] (1935), in the collections of the «Ural Library of Entertaining Regional Studies» series (1936–1939), in the literary and artistic almanac for teenagers «Boevye Rebiata» [«Fighting Children»] (1942–1958). The stories of I. I. Likstanov «Malyshok» [«The Little Boy»] (1947) and «Zelen kamen» [«Green Stone»] (1949), poems by E. E. Khorinskaya and others are also considered. An attempt is made to identify the characteristic features of the natural «portrait» of the Urals, constructed by the Ural writers «from within» the region. Conclusions are drawn regarding the connection between the theme of nature during this period and the cultivation of regional identity and patriotism. From an early age, kids were sistematically immersed in the local history agenda — from books for little children to serious texts with social issues
Overdiagnosis in breast cancer screening: the importance of length of observation period and lead time
No full textPMCID: PMC3706885This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
ChemInform Abstract: Engineered‐Serine Hydroxymethyltransferase from Streptococcus thermophilus for the Synthesis of α,α‐Dialkyl‐α‐Amino Acids.
No full textCan simply answering research questions change behaviour? Systematic review and meta analyses of brief alcohol intervention trials.
No full textBACKGROUND: Participant reports of their own behaviour are critical for the provision and evaluation of behavioural interventions. Recent developments in brief alcohol intervention trials provide an opportunity to evaluate longstanding concerns that answering questions on behaviour as part of research assessments may inadvertently influence it and produce bias. The study objective was to evaluate the size and nature of effects observed in randomized manipulations of the effects of answering questions on drinking behaviour in brief intervention trials. METHODOLOGY/PRINCIPAL FINDINGS: Multiple methods were used to identify primary studies. Between-group differences in total weekly alcohol consumption, quantity per drinking day and AUDIT scores were evaluated in random effects meta-analyses. Ten trials were included in this review, of which two did not provide findings for quantitative study, in which three outcomes were evaluated. Between-group differences were of the magnitude of 13.7 (-0.17 to 27.6) grams of alcohol per week (approximately 1.5 U.K. units or 1 standard U.S. drink) and 1 point (0.1 to 1.9) in AUDIT score. There was no difference in quantity per drinking day. CONCLUSIONS/SIGNIFICANCE: Answering questions on drinking in brief intervention trials appears to alter subsequent self-reported behaviour. This potentially generates bias by exposing non-intervention control groups to an integral component of the intervention. The effects of brief alcohol interventions may thus have been consistently under-estimated. These findings are relevant to evaluations of any interventions to alter behaviours which involve participant self-report
