Pre-Extraction of Wood Components Mild hydrothermal methods for a future materials biorefinery

Today there is an increasing urgency in discovering new, and more sustainable, replacements for fossil-based materials and chemicals. The biorefinery concept is promising in this context in that it relies on transforming biomass into a spectrum of commercial products. Wood is the primary bioresource in Scandinavia. It is mostly processed in the kraft pulping process used in the huge and important pulp and paper industry, thereby providing a suitable platform for future material biorefineries. This process allows for the efficient separation of lignin and cellulose, along with the option of adding a pretreatment step for the recovery of hemicelluloses. Among existing pretreatments, mild hydrothermal methods, such as hot water extraction and steam explosion, are promising since they allow recovery of hemicelluloses with minimal degradation. They are based on the acidic hydrolysis (autohydrolysis) of wood components and diffusive transport through the wood tissue. In steam explosion, the latter is enhanced by the advective transport in the pore system of the wood caused by the rapid release of the pressure. The focus of this work was to explore the possibility of using steam explosion and hot water extraction on different types of forest biomass, as well as to improve understanding of the underlying mechanisms. Performed in different experimental set ups, the work included determining the local composition of wood chips pretreated in different ways, continuous extraction of spruce and birch wood meal and a stepwise treatment of forest residues. The influence of autohydrolysis on the wood components, hemicelluloses (decreasing molar weight, deacetylation, cleavage of side groups, extraction and degradation), lignin (partial degradation and extraction) and cellulose (introduction of chain scissions) was analyzed. Moreover, the mechanism of acidification and the contribution of acetic acid were also investigated. The variations in the local composition of the wood chips obtained by steam explosion and hot water extraction were determined and related to the differences in mass transport and severity of the treatment. Finally, it was shown that the impact of steam explosion had a limited effect on refined wood residues, likely due to the relatively small size of the material

Dissolution of wood components during hot water extraction of birch

Autohydrolysis-based pretreatments enable extraction of hemicellulose from wood tissue prior to the paper pulp cooking processes enabling their further use as platform chemicals and in material applications. In this study, hot water extraction of birch meal was conducted in a small flow-through system. The combination of high surface area of the milled material with increased driving force induced by constant flow of freshwater, together with fast evacuation of extract, enabled a detailed study of the dissolution process. Based on the findings, deeper insight into acidification and autohydrolysis progress was obtained

Rola prasy harcerskiej we współczesnej komunikacji Związku Harcerstwa Polskiego

Adrian Wojtasz [[email protected]] – absolwent studiów magisterskich na kierunku nowe media w komunikacji oraz dziennikarstwo i komunikacja społeczna na Wydziale Nauk Politycznych i Dziennikarstwa Uniwersytetu im. Adama Mickiewicza w Poznaniu. Swoje zainteresowania badawcze koncentruje wokół systemów prasowych oraz ich powiązań z organizacjami medialnymi. Instruktor Związku Harcerstwa Polskiego w stopniu przewodnika.Praca w swoim głównym założeniu bada współczesną rolę, jaką pełnią cztery główne tytuły prasowe należące do Związku Harcerstwa Polskiego. W publikacji scharakteryzowano najważniejsze istniejące wydawnictwa ZHP wyodrębniając ich deklarowaną tematykę oraz rzeczywisty profil redakcyjny. Praca zawiera także omówienie sposobu organizacji redakcji poszczególnych tytułów. W toku rozważań i badań przeprowadzonych na obecnie wydawanych czasopismach określono rolę prasy harcerskiej we współczesnej komunikacji Związku Harcerstwa Polskiego

Mild Steam Explosion of Wood and Forest Residues in the Perspective of a Materials Biorefinery

The main objective of this work was to explore the prospects of using mild steam explosion as a pretreatment step in a forest based material biorefinery. During the steam explosion saturated steam is applied to the biomass at elevated pressure leading to an autohydrolysis of the lignocellulosic tissue, which is followed by a rapid pressure discharge, disintegrating and opening up the structure. As a consequence, the pretreatment enables the extraction of the most sensitive hemicelluloses and facilitates further processing, e.g. enzymatic treatment and chemical pulping. To investigate the effects rendered by the pretreatment, it was performed on two different types of forest biomass: Norway spruce wood chips and forest residues of mixed origin. The focus was on investigating the effects on the chemical structure of the material. In order to gain improved understanding of the fundamental mechanisms behind the pretreatment, the local effects on the composition of the wood tissue pretreated using steam explosion were investigated and compared with those accomplished by hot water extraction. Furthermore, cooking experiments were performed on pretreated forest residues to evaluate how the changes rendered by the pretreatment affect further processing of the material. The effects of the steam explosion were evaluated in terms of compositional analysis, molecular weight distribution and structural changes of extracted material (lignin and hemicelluloses). The results show that, due to the advective mass transport during the explosion step, steam explosion accomplishes a more even removal of hemicelluloses from the pretreated wood chips compared to the hot water extraction. Moreover, the impact of the steam explosion was found to be limited when material of a smaller size, namely refined forest residues, was pretreated

Effluents and residues from industrial sites for carbon dioxide capture: a review

The adverse effects of climate change calls for the rapid transformation of manufacturing processes to decrease the emissions of carbon dioxide. In particular, a lower carbon footprint can be achieved by capturing carbon dioxide at the site of emission. Here we review the use of industrial effluents, waste and residues to capture carbon dioxide. Waste include steelmaking slag, municipal solid waste incinerator ashes, combustion fly ash, black liquor, paper mill waste, mining waste, cement waste, construction and demolition waste, waste from the organic industry, and flue gas desulfurization gypsum waste. Capture capacities range from 2 to 800\ua0kg of carbon dioxide per ton of waste, depending on processes, waste type and conditions. Cement waste and flue gas desulfurization gypsum\ua0waste show the highest capture capacity per ton of waste

Observation of Extensive Chromosome Axis Remodeling during the "Diffuse-Phase" of Meiosis in Large Genome Cereals

The production of balanced fertile haploid gametes requires the faithful separation of paired (synapsed) chromosomes toward the end of meiotic prophase I (desynapsis). This involves the timely dissolution of the synaptonemal complex during the pachytene-diplotene transition, a stage traditionally referred to as the "diffuse stage." In species with large genomes such as, barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) we know most about the early stages of meiotic prophase I. There, synapsis initiates at the telomeric ends of chromosomes and progresses toward the centromeric regions through the ordered assembly of the synaptonemal complex (SC). Synapsis is impacted by recombination (crossing over, CO) which locally modifies the extent of chromatin compaction and extension. CO is uneven along the chromosomes, occurring mainly toward the telomeric regions resulting in a highly skewed distribution of recombination events. However, we know very little about the process of desynapsis which occurs during the "diffuse stage," where the synapsed and recombined chromosomes faithfully desynapse and separate into daughter cells. Here, using 3D-SIM super-resolution immuno-cytology combined with the use of antibodies directed against two crucial SC proteins, ASY1 and ZYP1, we followed the whole of meiosis I (i.e., both synapsis and desynapsis) in both barley and wheat. We showed that synapsis forms a characteristic tri-partite SC structure in zygotene (more clearly seen in barley). Toward the end of meiosis I, as the SC starts to disassemble, we show that extensive chromosome axis remodeling results in the formation of characteristic "tinsel-like" structures in both wheat and barley. By using amutant (des10) that is severely compromised in polymerization of ZYP1during synapsis, we show that tinsel structure formation during SC dissolution is not dependant on full synapsis and may relate instead to changes in expansion stress. Our observations highlight a potentially new role for ASYNAPSIS1 (ASY1) in desynapsis, in addition to chromosome synapsis and cohesion

BRCA1 establishes DNA damage signaling and pericentric heterochromatin of the X chromosome in male meiosis

During meiosis, DNA damage response (DDR) proteins induce transcriptional silencing of unsynapsed chromatin, including the constitutively unsynapsed XY chromosomes in males. DDR proteins are also implicated in double strand break repair during meiotic recombination. Here, we address the function of the breast cancer susceptibility gene Brca1 in meiotic silencing and recombination in mice. Unlike in somatic cells, in which homologous recombination defects of Brca1 mutants are rescued by 53bp1 deletion, the absence of 53BP1 did not rescue the meiotic failure seen in Brca1 mutant males. Further, BRCA1 promotes amplification and spreading of DDR components, including ATR and TOPBP1, along XY chromosome axes and promotes establishment of pericentric heterochromatin on the X chromosome. We propose that BRCA1-dependent establishment of X-pericentric heterochromatin is critical for XY body morphogenesis and subsequent meiotic progression. In contrast, BRCA1 plays a relatively minor role in meiotic recombination, and female Brca1 mutants are fertile. We infer that the major meiotic role of BRCA1 is to promote the dramatic chromatin changes required for formation and function of the XY body

The enigmatic meiotic dense body and its newly discovered component, SCML1, are dispensable for fertility and gametogenesis in mice.

Meiosis is a critical phase in the life cycle of sexually reproducing organisms. Chromosome numbers are halved during meiosis, which requires meiosis-specific modification of chromosome behaviour. Furthermore, suppression of transposons is particularly important during meiosis to allow the transmission of undamaged genomic information between generations. Correspondingly, specialized genome defence mechanisms and nuclear structures characterize the germ line during meiosis. Survival of mammalian spermatocytes requires that the sex chromosomes form a distinct silenced chromatin domain, called the sex body. An enigmatic spherical DNA-negative structure, called the meiotic dense body, forms in association with the sex body. The dense body contains small non-coding RNAs including microRNAs and PIWI-associated RNAs. These observations gave rise to speculations that the dense body may be involved in sex body formation and or small non-coding RNA functions, e.g. the silencing of transposons. Nevertheless, the function of the dense body has remained mysterious because no protein essential for dense body formation has been reported yet. We discovered that the polycomb-related sex comb on midleg-like 1 (SCML1) is a meiosis-specific protein and is an essential component of the meiotic dense body. Despite abolished dense body formation, Scml1-deficient mice are fertile and proficient in sex body formation, transposon silencing and in timely progression through meiosis and gametogenesis. Thus, we conclude that dense body formation is not an essential component of the gametogenetic program in the mammalian germ line