bluuebunny/crossref_metadata_2025_split huggingface dataset:
HPLC‐ICP‐MS method development to monitor arsenic speciation changes by human gut microbiota
Authors: Alava Pradeep , Tack Filip , Laing Gijs Du , de Wiele Tom Van 
Published: September 2011

ABSTRACTInorganic arsenic (iAs) has been classified as a type 1 carcinogen and has also been linked to several noncancerous health effects. Prior to 1995, the AsV methylation pathway was generally considered to be a detoxification pathway, but cellular and animal studies involving MMAIII (mono metyl arsonous acid) and DMAIII (dimethyl arsinous acid) have indicated that their toxicities meet or exceed that of iAs, suggesting an activation process. In addition, thiolated arsenic metabolites were observed in urine after oral exposure of inorganic arsenic in some studies, for which the toxicological profile was not yet fully characterized in human cells. Studies have revealed that microorganisms from the gut environment are important contributors to arsenic speciation changes. This presystemic metabolism necessitates the development of protocols that enable the detection of not only inorganic arsenic species, but also pentavalent and trivalent methylated, thiolated arsenicals in a gastrointestinal environment. We aim to study the biotransformation of arsenic (As) using a Simulator of the Human Intestinal Microbial Ecosystem (SHIME). To be able to analyze the arsenicals resulting from biotransformation reactions occurring in this system, a method using liquid chromatography hyphenated to an inductively coupled plasma mass spectrometer (HPLC‐ICP‐MS) was developed. A Hamilton PRP‐X100 anion exchange column was used. The method allowed separation, identification and quantification of AsIII(arsenite), AsV(arsenate), DMAV(dimethylarsinicacid), MMAV(monomethylarsonicacid) and MMMTA (monomethylmonothioarsenate). Attempts to optimize the same method for also separating MMAIII and DMAIII did not succeed. These compounds could be successfully separated using a method based on the use of a Zorbax C18 column. The properties of the column, buffer strength, pH and polar nature of mobile phase were monitored and changed to optimize the developed methods. Linearity, sensitivity, precision, accuracy and resolution of both methods were checked. The combination of the two methods allowed successful quantification of arsenic species in suspensions sampled in vitro from the SHIME reactor or in vivo from the human colon and feces. Copyright © 2011 John Wiley & Sons, Ltd.
The enhancement of neural stem cell survival and growth by coculturing with expanded sertoli cells in vitro
Authors: Shi Bingyang , Deng Lei , Shi Xiaolin , Dai Sheng , Zhang Hu , Wang Yonghong , Bi Jingxiu , Guo Meijin 
Published: September 2011

AbstractSertoli cells (SCs) have been described as the “nurse cells” of testis to provide essential growth factors and to create a proper environment for the development of other cells (e.g., germinal and neural stem cell). However, the physiological functions of the SCs obtained from different culture conditions are different in a coculturing system, and thus the optimal SC culturing condition should be investigated in vitro. In this paper, primary Sertoli cells were isolated from a 12‐day‐old mouse and expanded in two different culture conditions: a two dimensional (2D) plastic tissue disc and a three dimensional (3D) microcarrier culture system. They were then cocultured with neural stem cells (NSCs) isolated from 14‐day‐old mouse embryos. The metabolic activities of SCs2D(SCs in 2D) and SCs3D(SCs in 3D) and the amount of proteins secreted from two culturing systems were compared. The results show that the metabolic activity and the amount of secreted proteins from SCs3Dwere higher than both from SCs2D. Three coculturing groups: NSCs+SC2D, NSCs+SC3D, and NSCs +SC‐conditioned medium (SCCM, control group) were also compared regarding cell morphology and the numbers of neurons, neural outgrowths and neurospheres. The quantity of neurons, neural outgrowths and neurospheres were the highest in the NSCs+SC3Dgroup. SCs cultured in the 3D system had a strong trophic effect on NSCs and enhanced their survival and growth. Besides, the mRNA of trophic and nutritive factors such as Glial‐cell‐line‐derived neurotrophic factor (GDNF) and Interleukin‐1 α (IL‐1 α) secreted by the SCs from both 2D and 3D culture system were analyzed by real time‐PCR and gel assay. The mRNA transcription of GDNF and IL‐1α is more apparent in the 3D culture system than that from the 2D one. The coculturing system of NSCs+SC3Dis a promising candidate for future neural stem cell transplantation. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Metal–Ligand Cooperation in the Catalytic Dehydrogenative Coupling (DHC) of Polyalcohols to Carboxylic Acid Derivatives
Authors: Trincado Mónica , Kühlein Klaus , Grützmacher Hansjörg 
Published: September 2011

AbstractSeveral polyols, which are easily available from sugars through biochemical conversion or hydrogenolytic cleavage, are directly converted into carboxylic acids and amides. This efficient dehydrogenative coupling process, catalyzed by a rhodium(I) diolefin amido complex, is an attractive approach for the production of organic fine chemicals from renewable resources. This method tolerates the presence of several hydroxy groups and can be extended to the direct synthesis of lactams from the corresponding amino alcohols under mild conditions.
Acid‐Catalyzed Reactions of Twisted Amides in Water Solution: Competition between Hydration and Hydrolysis
Authors: Wang Binju , Cao Zexing 
Published: September 2011

AbstractThe acid‐catalyzed reactions of twisted amides in water solution were investigated by using cluster‐continuum model calculations. In contrast to the previous widely suggested concerted hydration of the CO group, our calculations show that the reaction proceeds in a practically stepwise manner, and that the hydration and hydrolysis channels of the CN bond compete. The Eigen ion (H3O+) is the key species involved in the reaction, and it modulates the hydration and hydrolysis reaction pathways. The phenyl substitution in the twisted amide not only activates the NCO bond, but also stabilizes the hydrolysis product through nN→πphenyl delocalization, leading exclusively to the hydrolysis product of the ring‐opened carboxylic acid. Generally, the twisted amides are more active than the planar amides, and such a rate acceleration results mainly from the increase in exothermicity in the first N‐protonation step; the second step of the nucleophilic attack is less affected by the twisting of the amide bond. The present results show good agreement with the available experimental observations.
ChemInform Abstract: A Simple Route for Highly Luminescent Quaternary Cu—Zn—In—S Nanocrystal Emitters.
Authors: Zhang Jie , Xie Renguo , Yang Wensheng 
Published: September 2011

AbstractCuZnInS3 nanocrystals are synthesized from mixtures of Zn(OAc)2, In(OAc)3, CuOAc, 1‐dodecanethiol, oleic acid, octadecene, and sulfur dissolved in oleylamine (150—240 °C for 10 min and 230 °C for 5 min).
ChemInform Abstract: Synthesis and Structure of [C6N4H20]0.5 [B5O6(OH)4]: A New Organically Templated Pentaborate with White‐Light‐Emission.
Authors: Yang Yang , Sun Jiang‐Bo , Cui Miao , Liu Rui‐Bin , Wang Yu , Meng Chang‐Gong 
Published: September 2011

AbstractTitle compound (II) crystallizes in the monoclinic space group P21/c with Z = 4 (single crystal XRD).
ChemInform Abstract: Rapid Self‐Assembly of Uranyl Polyhedra into Crown Clusters.
Authors: Sigmon Ginger E. , Burns Peter C. 
Published: September 2011

AbstractThree chemically distinct clusters built from 32 uranyl peroxide polyhedra, (NH4)40 [(UO2)32(O2)40(OH)24] (I), (NH4)40 [(UO2)32(O2)44(OH)26] (II), and a third one with a composition consistent with coprecipitation of (I) and (II), self‐assemble and crystallize within 15 min from aqueous solutions of uranyl nitrate, ammonium hydroxide, and hydrogen peroxide in different molar ratios under ambient conditions.
ChemInform Abstract: Taking Advantage of the Ambivalent Reactivity of Ynamides in Gold Catalysis: A Rare Case of Alkyne Dimerization.
Authors: Kramer Soeren , Odabachian Yann , Overgaard Jacob , Rottlaender Mario , Gagosz Fabien , Skrydstrup Troels 
Published: September 2011

AbstractThe formation and the nature of the dimeric products depend on the electronic nature of the substituents located on the nitrogen atom and on the alkyne terminus.
ChemInform Abstract: An Efficient Indium‐Mediated 2‐Bromoallylation of Aldehydes at Low Temperature in Aqueous DMF.
Authors: Kim Yu Mi , Lee Sangku , Kim Sung Hwan , Kim Jae Nyoung 
Published: September 2011

AbstractAn efficient synthesis of 2‐bromohomoallylic alcohols (III) is carried out via an In‐mediated Barbier‐type 2‐bromoallylation of aldehydes (I).
ChemInform Abstract: Silicon—(Thio)urea Lewis Acid Catalysis.
Authors: Hrdina Radim , Mueller Christian E. , Wende Raffael C. , Lippert Katharina M. , Benassi Mario , Spengler Bernhard , Schreiner Peter R. 
Published: September 2011

AbstractThe title complex, containing silicon activated by incorporation into a strained cycle and connection with a strongly electron‐withdrawing group, is generated in situ.
ChemInform Abstract: Enantiocontrolled Synthesis of β‐Branched α‐Amino Acids by Using CuI‐Catalyzed 1,4‐Addition of Glycine Imines to β‐Substituted gem‐Diactivated Olefins.
Authors: Hernandez‐Toribio Jorge , Gomez Arrayas Ramon , Carretero Juan C. 
Published: September 2011

AbstractGlutamic, pyroglutamic, and other β‐branched α‐amino acid derivatives are obtained with high levels of both syn‐diastereoselectivity and enantiocontrol, especially those with a β‐aromatic substituent.
ChemInform Abstract: Asymmetric Organocatalytic 1,6‐Conjugate Addition of Aldehydes to Dienic Sulfones.
Authors: Murphy John J. , Quintard Adrien , McArdle Patrick , Alexakis Alexandre , Stephens John C. 
Published: September 2011

AbstractThe process proceeds with complete diastereo‐ and enantioselectivity to afford highly interesting cyclic diene subunits.
ChemInform Abstract: Cinchona Alkaloid Amide Catalyzed Enantioselective Formal [2 + 2] Cycloadditions of Allenoates and Imines: Synthesis of 2,4‐Disubstituted Azetidines.
Authors: Denis Jean‐Baptiste , Masson Geraldine , Retailleau Pascal , Zhu Jieping 
Published: September 2011

AbstractAsymmetric formal [2 + 2] cycloaddition of N‐sulfonylimines (I) and (IV) with allenoates (II) is efficiently catalyzed by a bifunctional glycinamide‐containing quinidine organocatalyst to give azetidines (III) and (V), resp., in high enantioselectivity (up to 98% e.e.).
ChemInform Abstract: Gold(I)‐Catalyzed Formation of Benzo[b]furans from 3‐Silyloxy‐1,5‐enynes.
Authors: Hashmi A. Stephen K. , Yang Weibo , Rominger Frank 
Published: September 2011

AbstractA novel gold(I)‐catalyzed rearrangement of substrates (I) provides an efficient access to ring system (II) under mild conditions.
ChemInform Abstract: Asymmetric Construction of 3‐Vinylidene‐pyrrolidine Derivatives Containing Allene Moiety via Ag(I)/TF‐BiphamPhos‐Catalyzed 1,3‐Dipolar Cycloaddition of Azomethine Ylides with Diethyl 2‐(3,3‐Diphenylpropa‐1,2‐dienylidene) Malonate.
Authors: Xue Zhi‐Yong , Fang Xin , Wang Chun‐Jiang 
Published: September 2011

AbstractThe procedure provides a new and highly enantioselective method to prepare pyrrolidines of type (III).
ChemInform Abstract: Synthesis and in vitro Cytotoxic Evaluation of N‐Alkylbromo and N‐Alkylphthalimido‐isatins.
Authors: Singh Pardeep , Kaur Sharanjeet , Kumar Vipan , Bedi P. M. S. , Mahajan M. P. , Sehar Irum , Pal Harish Chandra , Saxena Ajit Kumar 
Published: September 2011

AbstractSynthesis and in vitro cytotoxic evaluation of a series of N‐alkylbromo (III) and N‐alkylphthalimido‐isatins (V) are reported.
ChemInform Abstract: Synthesis and Fluorescence Properties of 4‐Aminobenzo[f]isoindole Derivatives.
Authors: Levkov Igor V. , Voitenko Zoia V. , Zaporozhets Olga A. , Linnik Rostislav P. , Shishkina Svetalana V. , Shishkin Oleg V. 
Published: September 2011

AbstractThe fluorescence intensity of (II) depends on the water content in organic solvents.
ChemInform Abstract: Studies on the Reduction of the Nitro Group in 4‐Nitroindazoles by Anhydrous SnCl2 in Different Alcohols.
Authors: Abbassi N. , Rakib E. M. , Bouissane L. , Hannioui A. , Khouili M. , El Malki A. , Benchidmi M. , Essassi E. M. 
Published: September 2011

Abstract7‐Alkoxy‐4‐amino‐protected indazole and 4‐amino‐protected indazole derivatives are obtained by reduction of the nitro group in 4‐nitroindazoles using anhydrous stannous chloride in different alcohols.
ChemInform Abstract: Enantioselective Intramolecular Crossed Rauhut—Currier Reactions Through Cooperative Nucleophilic Activation and Hydrogen‐Bonding Catalysis: Scope and Mechanistic Insight.
Authors: Wang Xu‐Fan , Peng Liang , An Jing , Li Chao , Yang Qing‐Qing , Lu Liang‐Qiu , Gu Feng‐Long , Xiao Wen‐Jing 
Published: September 2011

AbstractThe title reaction features simple experimental procedures and is completely atom economical under benign conditions.
ChemInform Abstract: Enantioselective Organocatalytic Michael‐Hemiketalization Catalyzed by a trans‐Bifunctional Indan Thiourea Catalyst.
Authors: Gao Yaojun , Ren Qiao , Ang Swee‐Meng , Wang Jian 
Published: September 2011

AbstractIt is found that the thiourea efficiently promotes asymmetric Michael‐hemiketalization of the naphthoquinone (I) yielding benzochromenes of type (III) with excellent enantioselectivity.
ChemInform Abstract: Synthesis and anti‐HIV‐1 Activity of New Fluoro‐HEPT Analogues: An Investigation on Fluoro versus Hydroxy Substituents.
Authors: Loksha Yasser M. , Pedersen Erik B. , Loddo Roberta , La Colla Paolo 
Published: September 2011

AbstractA variety of new 1‐[(2‐hydroxyethoxy)methyl]‐6‐(phenylthio)thymine (HEPT) analogues is synthesized and evaluated for their activity against HIV‐1 wild type and mutant strains.
ChemInform Abstract: The Pyridyldiisopropylsilyl Group: A Masked Functionality and Directing Group for Monoselective ortho‐Acyloxylation and ortho‐Halogenation Reactions of Arenes.
Authors: Huang Chunhui , Chernyak Natalia , Dudnik Alexander S. , Gevorgyan Vladimir 
Published: September 2011

AbstractThe silyl moiety is an efficient and easily removable directing group for monoselective ortho‐acyloxylation and ortho‐halogenation of arenes.
ChemInform Abstract: Radical Addition Reaction of Bis(naphth‐1,8‐diyl‐8‐oxy)hydrophosphorane to Olefins.
Authors: Kajiyama Kazumasa , Itou Daisuke , Hazama Yuki , Yamamoto Yusuke , Miyamoto Takeshi K. 
Published: September 2011

AbstractThe title reaction is regioselective, and polymerization and reduction of the olefins are suppressed.
ChemInform Abstract: A Novel Mode of Reactivity for Gold(I): The Decarboxylative Activation of (Hetero)Aromatic Carboxylic Acids.
Authors: Cornella Josep , Rosillo‐Lopez Martin , Larrosa Igor 
Published: September 2011

AbstractAuCl(P(tBu)3) (II) AuCl(PPh3), and AuCl(PEt3) efficiently promote the decarboxylation of o‐substituted aromatic and heteroaromatic carboxylic acids to produce stable and isolable aryl‐gold complexes such as (III).
ChemInform Abstract: A Protecting Group‐Free Synthesis of the Antineoplastic Agent Combretastatin A4.
Authors: Guo Xiaotao , Zhang Dan , Yu Zhifang , Liu Tianzhen , Li Dachang , Li Chunbao 
Published: September 2011

AbstractThe presented method does not require protection of the phenolic hydroxy group and is simple and cost‐efficient.
Biophysical Investigations of GBV‐C E1 Peptides as Potential Inhibitors of HIV‐1 Fusion Peptide
Authors: Sánchez‐Martín Maria Jesús , Urbán Patricia , Pujol Montserrat , Haro Isabel , Alsina M. Asunción , Busquets M. Antònia 
Published: September 2011

AbstractFive peptide sequences corresponding to the E1 protein of GBV‐C [NCCAPEDIGFCLEGGCLV (P7), APEDIGFCLEGGCLVALG (P8), FCLEGGCLVALGCTICTD (P10), QAGLAVRPGKSAAQLVGE (P18), and AQLVGELGSLYGPLSVSA (P22)] were synthesized because they were capable of interfering with the HIV‐1 fusion peptide (HIV‐1 FP)–vesicle interaction. In this work the interaction of these peptides with the HIV‐1 FP, as well as with membrane models, was analyzed to corroborate their inhibition ability and to understand if the interaction with the fusion peptide takes place in solution or at the membrane level. Several studies were carried out on aggregation and membrane fusion, surface Plasmon resonance, and conformational analysis by circular dichroism. Moreover, in vitro toxicity assays, including cytotoxicity studies in 3T3 fibroblasts and hemolysis assays in human red blood cells, were performed to evaluate if these peptides could be potentially used in anti‐HIV‐1 therapy.Results show that P10 is not capable of inhibiting membrane fusion caused by HIV‐1 and it aggregates liposomes and fuses membranes, thus we decided to discard it for futures studies. P18 and P22 do not inhibit membrane fusion, but they inhibit the ability of HIV‐1 FP to form pores in bilayers, thus we have not discarded them yet. P7 and P8 were selected as the best candidates for future studies because they are capable of inhibiting membrane fusion and the interaction of HIV‐1 FP with bilayers. Therefore, these peptides could be potentially used in future anti‐HIV‐1 research.
Ultrafast Dynamics of UV‐Excited Imidazole
Authors: Crespo‐Otero Rachel , Barbatti Mario , Yu Hui , Evans Nicholas L. , Ullrich Susanne 
Published: September 2011

AbstractThe ultrafast dynamics of UV‐excited imidazole in the gas phase is investigated by theoretical nonadiabatic dynamics simulations and experimental time‐resolved photoelectron spectroscopy. The results show that different electronic excited‐state relaxation mechanisms occur, depending on the pump wavelength. When imidazole is excited at 239.6 nm, deactivation through the NH‐dissociation conical intersection is observed on the sub‐50 fs timescale. After 200.8 nm excitation, competition between NH‐dissociation and NH‐puckering conical intersections is observed. The NH‐dissociation to NH‐puckering branching ratio is predicted to be 21:4, and the total relaxation time is elongated by a factor of eight. A procedure for simulation of photoelectron spectra based on dynamics results is developed and employed to assign different features in the experimental spectra.
Der Einfluss politischer Rahmenbedingungen auf die Entwicklung des Wohnungsbaus
Authors: Eichener Volker 
Published: September 2011

AbstractTrotz einer minimalen Erholung im Jahr 2010 sinkt die Zahl der Baufertigstellungen beständig, so dass die aus sozial‐ und klimapolitischen Gründen erforderliche Erneuerung des Wohnungsbestands viel zu langsam voranschreitet. Der Rückgang des Wohnungsneubaus ist darauf zurückzuführen, dass die Rentabilität von Investitionen so gering ist, dass eine Förderung unentbehrlich ist, um die Rentabilitätskurve zu glätten, die von hohen Anfangsverlusten geprägt ist, bevor der Break Even erreicht ist. Tatsächlich sind die wohnungspolitischen Förderinstrumente in den vergangenen zwei Jahrzehnten abgebaut worden. Zusätzlich haben sich die mietrechtlichen, energiepolitischen und steuerrechtlichen Rahmenbedingungen für den Wohnungsbau verschlechtert. Eine Belebung des Wohnungsneubaus kann insbesondere erwartet werden, wenn die degressive Abschreibung wieder eingeführt und eine Kombinationsförderung des Bestandsersatzes in ganz Deutschland realisiert würde.Influence of political conditions on residential building. In spite of a minimal recovery in 2010, the number of residential building completions is constantly decreasing. Hence, the replacement of housing stock, which is required in order to meet objectives of social policy and climate policy, proceeds way too slowly. Residential building decreases because the return on investment is so low that subsidizing is required in order to straight the profitability curve which is characterized by high losses in the first years before the break even is reached. To the contrary, the instruments to promote residential building have been cut back in the last two decades. Furthermore, the developments of tenancy law, energy policy and taxation have led to unfavourable conditions for residential building. Residential building could be revived if declining‐balance depreciation and a combined subsidy of stock replacement (demolition and new building) is introduced (again).
Entwicklungsfähigkeit von Mauerwerk aus baustofflicher Sicht
Authors: Brameshuber Wolfgang , Koster Matthias , Graubohm Markus , Saenger Dorothea 
Published: September 2011

AbstractDie Entwicklung des Mauerwerks in den letzten Jahrzehnten wurde maßgeblich geprägt von ökologischen und ökonomischen Faktoren. Die Anforderungen an den Wärmeschutz von Gebäuden sind kontinuierlich gestiegen, was sich in einer stetigen Verbesserung der Wärmedämmeigenschaften des Mauerwerks niederschlägt. Steigende Lohnkosten führen zu einer fortschreitenden Rationalisierung des Mauerwerkbaus, was sich u. a. durch größere Steinformate, schnellere Vermörtelungstechniken oder auch vorgefertigte Wandelemente ausdrückt. Auch rücken ökologische Aspekte vermehrt in den Vordergrund. Die Herstellung der Wandbaustoffe soll möglichst ressourcen‐ und umweltschonend erfolgen. Parallel zu den Entwicklungen auf materieller Seite wird auch das Verhalten des Mauerwerks und seiner Bestandteile unter Lasteinwirkung immer genauer untersucht, in vielen Fällen unter Zuhilfenahme numerischer Modelle. Das Ziel hierbei ist, eine bessere Beschreibung des Tragverhaltens zu erhalten, um dadurch die einzelnen Komponenten des Mauerwerks besser auszunutzen und somit Material einsparen zu können.Development potential of masonry from the vantage point of the building material. The development of masonry during the last decades was mainly influenced by ecological and economical factors. The requirements on the heat protection of buildings were continuously increased which results in a constant improvement of the heat insulation properties of masonry constructions. Increasing labour costs entail a progressing rationalisation of masonry which leads, among other things, to larger masonry units, improved mortar applying techniques or prefabricated wall components. Ecological aspects also come more and more to the fore. The production of wall materials should be resource‐efficient and environmentally friendly. Parallel to the developments on the material side the behaviour of masonry and its components under load action is investigated with increased accuracy often with the use of numerical models. The objectives are a better understanding of the load bearing behaviour for a maximum exploitation of the masonry components, and consequently to save material.
Konstruktiv‐technische Gestaltung von Bauwerken und Bauteilen im Abgleich mit zukünftigen nationalen und europäischen Vorgaben zur Energieeffizienz von Gebäuden
Authors: Vogdt Frank U. , Piesker Julia 
Published: September 2011

AbstractVielfältige nationale und europäische Gesetze, Verordnungen, Richtlinien oder Normen zielen auf die Energieeffizienz von Gebäuden ab. Dabei steht jedoch in den bisherigen Betrachtungen nur die Betriebsphase im Fokus. Diesbezüglich wurde insbesondere im Neubaubereich nicht zuletzt durch die Einführung der Energieeinsparverordnung EnEV 2009 viel erreicht. Die geplante weitere Novellierung der EnEV (EnEV 2012) wirft bereits ihre Schatten voraus. Aus weiter verschärften Anforderungen würden nochmals zusätzliche Aufwendungen für einen erhöhten Standard des baulichen Wärmeschutzes sowie für die Anlagentechnik resultieren – insbesondere auch zur Nutzung regenerativer Energien. Damit gewinnt der Energieaufwand für die Herstellung der Bauprodukte sowie die Errichtung des Bauwerks zunehmend an Bedeutung. Eine Lebenszyklusbetrachtung und eine Bewertung der Aspekte des nachhaltigen Bauens, zum Beispiel gemäß dem Leitfaden des Bundesministeriums für Verkehr, Bau und Stadtentwicklung, erweitern den Bewertungszeitraum auf den gesamten Lebenszyklus des Gebäudes. Anhand von exemplarisch untersuchten Beispielen von Einfamilienhäusern wird dokumentiert, dass eine solche Lebenszyklusanalyse eine sinnvolle Ergänzung zur Optimierung von Planungsvarianten darstellen kann, wenn diese Analyse an konkrete, die Baupraxis weitgehend realistisch abbildende Rahmenbedingungen gebunden ist.