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  • 1
    Language: English
    In: International journal of biometeorology, 2015-07, Vol.59 (7), p.827-835
    Description: Species with transcontinental distribution or spread over wide geographical regions develop populations with growth traits genetically adapted to the local climate. The aim of this study was to investigate the ecotypic sensitivity of bud break, a strong adaptive trait, to a changing environment. Six phenological phases of bud break were monitored daily on black spruce [Picea mariana (Mill.) BSP] seedlings submitted to different temperatures (12, 16 and 20 °C) and photoperiods (14, 18 and 22 h). Six provenances were tested in growth chambers, produced from seeds collected along the whole latitudinal range of the closed boreal forest in Quebec, Canada. Bud break lasted 13.3 days on average and occurred earlier in seedlings from colder sites. The annual temperature of the sites suitably tracked the clinal variation among ecotypes, providing a clear biological explanation for the environmental signal driving the adaptive divergence of populations to the local climate. Increasing temperature induced an earlier bud break according to a non-linear pattern with greater advancements observed between 12 and 16 °C. Photoperiod was significant, but sensitivity analysis indicated that its effect on bud break was marginal with respect to temperature. No interaction of provenance × treatment was observed, demonstrating an ecotypic convergence of the responses to both factors. Changes in the growing conditions could substantially modify the synchronization between bud phenology and climate, thus exposing the developing meristems of black spruce to frost damage. However, similar advancements of bud break could be expected in the different ecotypes subjected to warmer temperatures or longer day lengths.
    Subject(s): Boreal forest ; Temperature ; Environmental Health ; Biophysics and Biological Physics ; Plant Physiology ; Photoperiod ; Environment, general ; Animal Physiology ; Phenology ; Environment ; Ecotype ; Picea mariana ; Meteorology ; Adaptation, Physiological ; Climate Change ; Picea - growth & development ; Seasons ; Seedlings - growth & development ; Analysis ; Greenhouse effect ; Global temperature changes ; Index Medicus
    ISSN: 0020-7128
    E-ISSN: 1432-1254
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 2
    Language: English
    In: Global change biology, 2017-01, Vol.23 (1), p.446-454
    Description: Global warming is diurnally asymmetric, leading to a less cold, rather than warmer, climate. We investigated the effects of asymmetric experimental warming on plant phenology by testing the hypothesis that daytime warming is more effective in advancing bud break than night‐time warming. Bud break was monitored daily in Picea mariana seedlings belonging to 20 provenances from Eastern Canada and subjected to daytime and night‐time warming in growth chambers at temperatures varying between 8 and 16 °C. The higher advancements of bud break and shorter times required to complete the phenological phases occurred with daytime warming. Seedlings responded to night‐time warming, but still with less advancement of bud break than under daytime warming. No advancement was observed when night‐time warming was associated with a daytime cooling. The effect of the treatments was uniform across provenances. Our observations realized under controlled conditions allowed to experimentally demonstrate that bud break can advance under night‐time warming, but to a lesser extent than under daytime warming. Prediction models using daily timescales could neglect the diverging influence of asymmetric warming and should be recalibrated for higher temporal resolutions.
    Subject(s): bud burst ; minimum temperature ; phenology ; ecotype ; Picea mariana ; maximum temperature ; climate change ; Canada ; Climate ; Global Warming ; Temperature ; Seasons ; Picea - growth & development ; Analysis ; Global temperature changes ; Index Medicus
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 3
    Language: English
    In: Oecologia, 2007-05-01, Vol.152 (1), p.1-12
    Description: Temperature is the most important factor affecting growth at high altitudes. As trees use much of the allocated carbon gained from photosynthesis to produce branches and stems, information on the timing and dynamics of secondary wood growth is crucial to assessing temperature thresholds for xylogenesis. We have carried out histological analyses to determine cambial activity and xylem cell differentiation in conifers growing at the treeline on the eastern Alps in two sites during 2002- 2004 with the aim of linking the growth process with temperature and, consequently, of defining thresholds for xylogenesis. Cambial activity occurred from May to July-August and cell differentiation from May-June to September-October. The earliest start of radial enlargement was observed in stone pine in mid-May, while Norway spruce was the last species to begin tracheid differentiation. The duration of wood formation varied from 90 to 137 days, depending on year and site, with no difference between species. Longer durations were observed in trees on the south-facing site because of the earlier onset and later ending of cell production and differentiation. The threshold temperatures at which xylogenesis had a 0.5 probability of being active were calculated by logistic regressions. Xylogenesis was active when the mean daily air temperature was 5.6-8.5°C and mean stem temperature was 7.2-9°C. The similar thresholds among all trees suggested the existence of thermal limits in wood formation that correspond with temperatures of 6-8°C that are supposed to limit growth at the treeline. Different soil temperature thresholds between sites indicated that soil temperature may not be the main factor limiting xylogenesis. This study represents the first attempt to define a threshold through comparative assessment of xylem growth and tissue temperatures in stem meristems at high altitudes.
    Subject(s): Trees ; Cell growth ; Xylem ; Tree growth ; Tracheids ; Timberlines ; Cell differentiation ; Ecophysiology ; Stems ; Growth rings ; Soil temperature ; Life Sciences ; Alps ; Tree ring ; Treeline ; Ecology ; Plant Sciences ; Cambial activity ; Fundamental and applied biological sciences. Psychology ; Biological and medical sciences ; General aspects ; Animal and plant ecology ; Animal, plant and microbial ecology ; Temperature ; Xylem - cytology ; Coniferophyta - growth & development ; Periodicity ; Xylem - growth & development ; Cell Differentiation ; Seasons ; Wood - growth & development ; Altitude ; Index Medicus
    ISSN: 0029-8549
    E-ISSN: 1432-1939
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 4
    Language: English
    In: Global change biology, 2014-07, Vol.20 (7), p.2261-2271
    Description: In cold climates, the expected global warming will lead to earlier cambial resumptions in spring, with a resultant lengthening of the growing season but unknown consequences on forest productivity. The phenological traits of cambium activity and xylem formation were analyzed at a short time scale along a thermal gradient represented by an alti‐latitudinal range from the 48th to 53rd parallels and covering the whole closed black‐spruce [Picea mariana (Mill.) BSP] forest in Quebec, Canada. A hypothesis was tested that warmer temperatures influence cambium phenology, allowing longer duration and higher intensity of growth, and resulting in proportionally increased xylem production. From April to October 2012, cell division in cambium and post‐cambial differentiation of xylem were observed on anatomical sections obtained from microcores collected weekly from the stem of fifty trees. The southern and warmer site was characterized by the highest radial growth, which corresponded to both the highest rates and longest durations of cell production. The differences in terms of xylem phenology and growth were marginal between the other sites. Xylem growth was positively correlated with rate and duration of cell production, with the latter explaining most variability in growth. Within the range analyzed, the relationship between temperature and most phenological phases of xylogenesis was linear. On the contrary, temperature was related with cell production according to an exponential pattern. Periods of xylogenesis of 14 days longer (+13.1%) corresponded to a massive increase in cell production (33 cells, +109%). This disproportionate change occurred at a May–September average temperature of ca. 14 °C and a snow‐free period of 210–235 days. At the lower boundary of the distribution of black spruce, small environmental changes allowing marginal lengthening of the period of cell division could potentially lead to disproportionate increases in xylem cell production, with substantial consequences for the productivity of this boreal species.
    Subject(s): boreal forest ; climate warming ; phenology ; temperature ; black spruce ; growth ; threshold ; Picea mariana ; General forest ecology ; General aspects ; Animal, plant and microbial ecology ; Exact sciences and technology ; External geophysics ; Biological and medical sciences ; Climatology. Bioclimatology. Climate change ; Animal and plant ecology ; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology ; Fundamental and applied biological sciences. Psychology ; Forestry ; Earth, ocean, space ; Meteorology ; Cambium - growth & development ; Temperature ; Climate Change ; Time Factors ; Picea - growth & development ; Quebec ; Xylem - growth & development ; Seasons ; Trees - growth & development ; Analysis ; Global temperature changes ; Index Medicus
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 5
    Language: English
    In: Annals of botany, 2011-09-01, Vol.108 (3), p.429-438
    Description: • Background and Aims Our knowledge about the influences of environmental factors on tree growth is principally based on the study of dominant trees. However, tree social status may influence intra-annual dynamics of growth, leading to differential responses to environmental conditions. The aim was to determine whether withinstand differences in stem diameters of trees belonging to different crown classes resulted from variations in the length of the growing period or in the rate of cell production. • Methods Cambial activity was monitored weekly in 2006 for three crown classes in a 40-year-old silver-fir (Abies alba) plantation near Nancy (France). Timings, duration and rate of tracheid production were assessed from anatomical observations of the developing xylem. • Key Results Cambial activity started earlier, stopped later and lasted longer in dominant trees than in intermediate and suppressed ones. The onset of cambial activity was estimated to have taken 3 weeks to spread to 90 % of the trees in the stand, while the cessation needed 6 weeks. Cambial activity was more intense in dominant trees than in intermediate and suppressed ones. It was estimated that about 75 % of tree-ring width variability was attributable to the rate of cell production and only 25 % to its duration. Moreover, growth duration was correlated to tree height, while growth rate was better correlated to crown area. • Conclusions These results show that, in a closed conifer forest, stem diameter variations resulted principally from differences in the rate of xylem cell production rather than in its duration. Tree size interacts with environmental factors to control the timings, duration and rate of cambial activity through functional processes involving source-sink relationships principally, but also hormonal controls.
    Subject(s): Trees ; Growing seasons ; Social classes ; Xylem ; Tree growth ; Tracheids ; Cell walls ; Tree crowns ; Climate models ; Growth rings ; Abies - cytology ; Xylem - cytology ; Ecosystem ; Abies - growth & development ; Xylem - growth & development ; Trees - growth & development ; France ; Cambium - physiology ; Index Medicus ; Life Sciences ; Botanics ; Vegetal Biology ; tree-ring formation ; social status ; tree-to-tree competition ; xylem cell differentiation ; silver fir (Abies alba) ; forest-stand structure ; Original ; wood anatomy ; Cambial activity
    ISSN: 0305-7364
    E-ISSN: 1095-8290
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
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  • 6
    Language: English
    In: ChemCatChem, 2018-04-09, Vol.10 (7), p.1512-1525
    Description: The manufacturing of a three‐dimensional product from a computer‐driven digital model (3D printing) has found extensive applications in several fields. Additive manufacturing technologies offer the possibility to fabricate ad hoc tailored products on demand, at affordable prices, and have been employed to make customized and complex items for actual sale. However, despite the great progress and the countless opportunities offered by the 3D printing technology, surprisingly a relatively limited number of applications have been documented in organic chemistry. This Minireview will focus specifically on the exploitation of additive manufacturing technologies in the synthesis of organic compounds, and, in particular, on the use of 3D‐printed catalysts and 3D printed reactors, and on the fabrication and use of 3D printed flow reactors. 3D printing has countless possibilities in many industries and areas of life. This Minireview will focus specifically on the exploitation of additive manufacturing technologies in the synthesis of organic compounds, and, in particular, on the use of 3D‐printed catalysts and 3D printed reactors, and on the fabrication and use of 3D printed flow reactors.
    Subject(s): additive manufacturing ; 3D printed catalysts ; microfluidics ; 3D printed devices ; flow reactors ; 3D printing ; Digital computers ; Organic chemistry ; Three dimensional printing ; Reactors ; Three dimensional flow ; Additive manufacturing ; 3-D printers ; Three dimensional models ; Organic compounds
    ISSN: 1867-3880
    E-ISSN: 1867-3899
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 7
    Language: English
    In: Journal of experimental botany, 2012-01-01, Vol.63 (5), p.2117-2126
    Description: Although habitually considered as a whole, xylogenesis is a complex process of division and maturation of a pool of cells where the relationship between the phenological phases generating such a growth pattern remains essentially unknown. This study investigated the causal relationships in cambium phenology of black spruce [ (Mill.) BSP] monitored for 8 years on four sites of the boreal forest of Quebec, Canada. The dependency links connecting the timing of xylem cell differentiation and cell production were defined and the resulting causal model was analysed with d-sep tests and generalized mixed models with repeated measurements, and tested with Fisher’s C statistics to determine whether and how causality propagates through the measured variables. The higher correlations were observed between the dates of emergence of the first developing cells and between the ending of the differentiation phases, while the number of cells was significantly correlated with all phenological phases. The model with eight dependency links was statistically valid for explaining the causes and correlations between the dynamics of cambium phenology. Causal modelling suggested that the phenological phases involved in xylogenesis are closely interconnected by complex relationships of cause and effect, with the onset of cell differentiation being the main factor directly or indirectly triggering all successive phases of xylem maturation.
    Subject(s): Trees ; Cell growth ; Xylem ; Lignification ; Tracheids ; Cell walls ; Phenology ; Cambium ; Cellular differentiation ; Growth rings ; RESEARCH PAPER ; Fundamental and applied biological sciences. Psychology ; Biological and medical sciences ; Plant physiology and development ; Forestry ; Climate ; Picea - physiology ; Quebec ; Cambium - growth & development ; Xylem - cytology ; Models, Biological ; Picea - growth & development ; Cell Wall - metabolism ; Plant Stems - cytology ; Xylem - growth & development ; Cell Differentiation ; Cambium - cytology ; Wood - growth & development ; Picea - cytology ; Plant Stems - growth & development ; Index Medicus ; xylogenesis ; cell production ; d-sep test ; Research Papers ; cell differentiation ; secondary wall formation ; Causal modelling ; Picea mariana
    ISSN: 0022-0957
    E-ISSN: 1460-2431
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 8
    Language: English
    In: Annals of botany, 2015-03-01, Vol.115 (4), p.629-639
    Description: A series of studies have shown that temperature triggers the onset of xylogenesis of trees after winter dormancy. However, little is known about whether and how moisture availability influences xylogenesis in spring in drought-prone areas. Xylogenesis was monitored in five mature Qilian junipers (Juniperus przewalskii) by microcore sampling from 2009 to 2011 in a semi-arid area of the north-eastern Tibetan Plateau. A simple physical model of xylem cell production was developed and its sensitivity was analysed. The relationship between climate and growth was then evaluated, using weekly wood production data and climatic data from the study site. Delayed onset of xylogenesis in 2010 corresponded to a negative standardized precipitation evapotranspiration index (SPEI) value and a continuous period without rainfall in early May. The main period of wood formation was in June and July, and drier conditions from May to July led to a smaller number of xylem cells. Dry conditions in July could cause early cessation of xylem differentiation. The final number of xylem cells was mainly determined by the average production rate rather than the duration of new cell production. Xylem growth showed a positive and significant response to precipitation, but not to temperature. Precipitation in late spring and summer can play a critical role in the onset of xylogenesis and xylem cell production. The delay in the initiation of xylogenesis under extremely dry conditions seems to be a stress-avoidance strategy against hydraulic failure. These findings could thus demonstrate an evolutionary adaptation of Qilian juniper to the extremely dry conditions of the north-eastern Tibetan Plateau.
    Subject(s): ORIGINAL ARTICLES ; Juniperus - growth & development ; Climate ; Rain ; Snow ; Droughts ; Seasons ; Tibet ; Wood - growth & development ; Index Medicus ; standardized precipitation evapotranspiration index ; wood formation ; onset of xylogenesis ; drought ; Juniperus przewalskii ; SPEI ; xylem production rate ; juniper ; Original ; Semi-arid forest ; xylem differentiation
    ISSN: 0305-7364
    E-ISSN: 1095-8290
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 9
    Language: English
    In: Journal of chemical education, 2020-05-12, Vol.97 (5), p.1391-1395
    Description: In this paper, a teaching approach for the comprehension of the symmetry properties of an aperiodic crystal structure was described. Building a continuous-fill (quasi)­crystalline pattern with the support of 3D-printed Penrose tiles, students can grasp the lack of translational symmetry typical of an aperiodic crystal.
    Subject(s): Teaching methods ; Crystal lattices ; Three dimensional printing ; Tiles ; Crystals ; Comprehension ; 3-D printers ; Crystal structure ; Symmetry
    ISSN: 0021-9584
    E-ISSN: 1938-1328
    Source: Hellenic Academic Libraries Link
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 10
    Language: English
    In: Angewandte Chemie (International ed.), 2017-04-03, Vol.56 (15), p.4290-4294
    Description: 3D‐printed flow reactors were designed, fabricated from different materials (PLA, HIPS, nylon), and used for a catalytic stereoselective Henry reaction. The use of readily prepared and tunable 3D‐printed reactors enabled the rapid screening of devices with different sizes, shapes, and channel dimensions, aimed at the identification of the best‐performing reactor setup. The optimized process afforded the products in high yields, moderate diastereoselectivity, and up to 90 % ee. The method was applied to the continuous‐flow synthesis of biologically active chiral 1,2‐amino alcohols (norephedrine, metaraminol, and methoxamine) through a two‐step sequence combining the nitroaldol reaction with a hydrogenation. To highlight potential industrial applications of this method, a multistep continuous synthesis of norephedrine has been realized. The product was isolated without any intermediate purifications or solvent switches. Homemade reactors: Stereoselective catalytic reactions were conducted in tunable homemade 3D‐printed mesoreactors. This method was applied to the continuous‐flow synthesis of biologically active chiral 1,2‐amino alcohols in a two‐step sequencing combining a nitroaldol reaction and hydrogenation.
    Subject(s): nitroaldol reactions ; amino alcohols ; 3D printing ; stereoselective catalysis ; flow reactors ; Hydrogenation ; Usage ; Index Medicus
    ISSN: 1433-7851
    E-ISSN: 1521-3773
    Source: Alma/SFX Local Collection
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