The Road traveled to becoming a safe high school

Many urban school districts share a common profile of high dropout rates, low graduation rates, high discipline statistics and acts of school violence, and low student achievement on assessments. Researchers have argued high schools are teaching students in ways that are not only ineffective but also fail to provide the requisite tools for students to achieve success in the 21st century (Gates Foundation, 2010). Additional voices claim urban high schools are not adequately preparing students to become successful citizens for a knowledge-based society (Cuban, 2007). Using qualitative methodology, this naturalistic study revealed five factors that contribute to creating a safe urban high school in a large school district. Open, Axial and selective coding were used to generate understandings and linkages from the interviews, observations, artifacts and literature related to high school reform and school safety. Five research questions anchored the basis for this study. Findings from this study revealed that principal leadership and learning proved to be two significant factors that characterize a safe school. Findings also revealed internal and external factors that appear to have contributed to the development of a previously unsafe high school to being a safe one. Specifically - resources, administrative support and community context contributed to one urban high school becoming safe. The study report concludes with the introduction of an organizing framework related to factors that contribute to a safe school

Base-Catalyzed Depolymerization of Lignin: History, Challenges and Perspectives

Bio-based phenolic compounds available from lignin are promising candidates for industrial application, e.g., within polymer resins or as biogenic fuel substitutes. Among numerous conversion methods for the valorization of lignin, the base-catalyzed depolymerization (BCD) has considerable advantages with respect to other processes. By this method, lignin and lignin-containing biorefinery streams can be catalytically transferred to valuable, defined products with tailored specifications. Continuous process operation allows conversions at short residence times and, thus, enables its industrial implementation more easily due to economic reasons. This review reflects the development in the field of BCD on various types of lignin. A historical overview will be given and the principal application of the method is shown. Challenges for operations are addressed, mainly to the development of efficient and selective methods for product separation and purification of the alkylphenolic moieties and the reduction of char formation during the process. An outlook will be given by showing trends and perspectives, especially in the field of industrial applications. Here, hydrotreatment methods for refining BCD intermediates for fuel and platform chemical production are shown. Furthermore, the application of BCD for the conversion of woody biomass and black liquor is discussed

Kupfervermittelte oxidative Heterocyclisierungen

Einfache und effiziente Synthesen neuartiger Heterocyclen sind von großem synthesechemischen Interesse. Kupfervermittelte oxidative Cyclisierungsreaktionen bieten eine elegante Möglichkeit zur Knüpfung von Kohlenstoff-Stickstoff-Bindungen und ermöglichen somit den Zugang zu zahlreichen stickstoffhaltigen Heterocyclen. Eine Reihe verschiedener heterocyclisch substituierter Hydrazone (1 und 3) wurden kupferassistiert zu den entsprechenden 1,2,4-Triazolo[4,3-a]pyridinen 2 und 1,2,4-Triazolo[4,3-a]quinoxalinen 4 oxidiert. Durch Einführung unterschiedlicher Funktionalitäten in das Substratmolekül wurde eine breite Produktvielfalt erhalten. Am Beispiel der Verbindung 5 wurde außerdem gezeigt, dass auch 3-Aminoacrylate in einer Zweielektronen-Oxidation mittels stöchiometrischer Mengen an Kupfer(II)-chlorid zu Imidazo[1,5-a]pyridin-2H-ylidenen (6) reagieren. Bei der kupferassistierten Umsetzung der heterocyclischen Aldimine (10 und 13) von 1-Pyridin-2-ylethanamin (9a) sowie 1-(1-Methyl-1H-imidazol-2-yl)ethanamin (9b) wurden neben den Imidazo[1,5-a]pyridinen 11 und 14 auch heterocyclisch substituierte Pyridine (12 und 15) gebildet. Diese entstehen in der Koordinationssphäre des Kupfers durch aufeinanderfolgende Sequenzen von Oxidations- und [4+2]-Cycloadditionsreaktionen zweier Aldiminmoleküle. Durch Einsatz des 1-Pyridin-2-ylpropanamins (9c) im Substratmolekül wurde zudem die Bildung des 1,4-Diazatricyclo-[3.2.1.02,7]oct-3-ens 18 beobachtet, dessen tricyclische Grundstruktur bisher noch nicht beschrieben wurde. Die exakte Analyse sowie Strukturuntersuchungen an Kupferkomplexen führten zu Mechanismusvorschlägen. Einige der dargestellten Pyridinderivate wurden pharmakologisch untersucht und wiesen zytostatische Wirkung auf. Dabei stellten sich 12a sowie die Platin(II)-Komplexe 23 und 24 als besonders wirksam gegenüber einzelnen Tumorzelllinien heraus. In Anlehnung an den postulierten Reaktionsmechanismus der Pyridinbildung wurde die kupferassistierte Umsetzung von heterocyclisch substituierten Aldiminen mit verschiedenen Dienophilen untersucht. Bei der Reaktion mit Dimethylacetylendicarboxylat, 1,4-Naphthochinon und 1,4-Benzochinon erhielt man Produkte, die infolge oxidativer [3+2]-Cycloadditionsreaktionen entstanden. Die 2H-Pyrrole (25), Isoindol-4,9-diole (29) und Benzo[f]isoindol-4,9-diole (30) konnten zudem auch kupferkatalysiert in Gegenwart von Luftsauerstoff selektiv und in guten Ausbeuten erhalten werden

Expression of gibberellin 20-oxidase1 (AtGA20ox1) in Arabidopsis seedlings with altered auxin status is regulated at multiple levels

Bioactive gibberellins (GAs) affect many biological processes including germination, stem growth, transition to flowering, and fruit development. The location, timing, and level of bioactive GA are finely tuned to ensure that optimal growth and development occur. The balance between GA biosynthesis and deactivation is controlled by external factors such as light and by internal factors that include auxin. The role of auxin transport inhibitors (ATIs) and auxins on GA homeostasis in intact light-grown Arabidopsis thaliana (L.) Heynh. seedlings was investigated. Two ATIs, 1-N-naphthylthalamic acid (NPA) and 1-naphthoxyacetic acid (NOA) caused elevated expression of the GA biosynthetic enzyme AtGA20-oxidase1 (AtGA20ox1) in shoot but not in root tissues, and only at certain developmental stages. It was investigated whether enhanced AtGA20ox1 gene expression was a consequence of altered flow through the GA biosynthetic pathway, or was due to impaired GA signalling that can lead to enhanced AtGA20ox1 expression and accumulation of a DELLA protein, Repressor of ga1-3 (RGA). Both ATIs promoted accumulation of GFP-fused RGA in shoots and roots, and this increase was counteracted by the application of GA4. These results suggest that in ATI-treated seedlings the impediment to DELLA protein degradation may be a deficiency of bioactive GA at sites of GA response. It is proposed that the four different levels of AtGA20ox1 regulation observed here are imposed in a strict hierarchy: spatial (organ-, tissue-, cell-specific) > developmental > metabolic > auxin regulation. Thus results show that, in intact auxin- and auxin transport inhibitor-treated light-grown Arabidopsis seedlings, three other levels of regulation supersede the effects of auxin on AtGA20ox1

Neue Strategien - Holz als Rohstoff für die chemische Industrie

Industriezweige wie die chemische Industrie, die stark vom Erdöl ­abhängen, suchen nach alternativen Rohstoffquellen. Holz, nachhaltig­ und in relevanten Mengen verfügbar, bietet eine Basis ­für eine alternative Herstellung von Plattformchemikalien. Nach dem Konzept der Bioraffinerie wird es ähnlich wie in einer erdöl­basierten Raffinerie in seine Grundbestandteile Cellulose, Hemi­cellulose und Lignin fraktioniert und zu Grundstoffen oder komplexen Zwischenstoffen für die chemische Industrie umgewandelt. Hierfür sind neu­artige biotechnologische und chemische Synthese- und Prozess­strategien notwendig

Production of Bio-Phenols for Industrial Application: Scale-Up of the Base-Catalyzed Depolymerization of Lignin

Objective of this study was the investigation on the up-scaling of base-catalyzed depolymerization (BCD) of lignin to pilot plant dimension. The cleavage process was carried out in dilute alkaline solution at temperatures up to 340°C and a pressure of 25 MPa in a continuously operated tubular flow reactor with throughputs up to 20 kg/h. Investigations included the proof of the feasibility of the scale-up as well as a parameter study on the cleavage of hardwood Organosolv lignin and softwood Kraft lignin within the established pilot plant. Yields and molecular compositions of the isolated product fractions BCD-oil (liquid phenolic fraction) and BCD-oligomers (solid phenolic fraction) are similar to those described in technical lab scale, showing a good scalability. Here, BCD-oils rich in phenolic monomers such as guaiacol, catechol and/or syringol were obtained with a content of up to 13.3 wt% and 14.5 wt% from Organosolv lignin and Kraft lignin, respectively. Formation of BCD-oligomers strongly depends on temperature and residence times within the reactor