Differences in branch characteristics of Scots pine (Pinus sylvestris L.) genetic entries grown at different spacing

• We studied the differences in branch characteristics along the stems of six different genetic entries of 20 year old Scots pines (Pinus sylvestris L.) grown at different spacing (current stand density range 2000–4000 trees ha−1) in central Finland. Furthermore, we studied the phenotypic correlations between yield, wood density traits and branch characteristics. All the genetic entries had Kanerva pine (plus tree S1101) as a father tree, whereas the mother tree represented Finnish plus trees from southern, central and northern Finland. • Spacing affected all yield traits, wood density and living branch characteristics such as relative average branch diameter and relative cumulative branch area (p < 0.05). As a comparison, genetic entry affected height, while origin group (southern, central and northern ones) affected most of the studied traits. Regardless of spacing, the northern origin had, on average, the largest stem diameter and highest wood density, while the central one was the tallest one. Furthermore, average branch diameter along the stem was affected by branch age, origin group and spacing, while average branch angle was affected by branch age and genetic entry (p < 0.05). • In general the average branch size could be decreased especially in lower tree canopy by denser spacing during the early phase of the rotation, but only at the expense of tree growth. Correspondingly differences between origins are mainly related to their differences in stem growth

Water and nitrogen processes along a typical water flowpath and streamwater exports from a forested catchment and changes after clear-cutting: a modelling study

International audienceA two dimensional model, FEMMA, to describe water and nitrogen (N) fluxes within and from a forested first-order catchment (Kangasvaara in Eastern Finland) was constructed by linking the most significant processes affecting the fluxes of water, ammonium, nitrate and dissolved organic nitrogen along a hillslope from the water divide to the stream. The hillslope represents the average flowpath of water in the catchment and the model was used to estimate the N fluxes for a catchment in eastern Finland before and after clear-cutting. The simulated results were in reasonable agreement with the nitrate, dissolved organic N and dissolved total N measurements from the study catchment and with other results in the literature. According to the simulations, the major sinks of N after clear-cutting were immobilisation by soil microbes, uptake by ground vegetation and sorption to soil. These sinks increased downslope from the clear-cut area, indicating the importance of an uncut buffer zone between the stream and the clear-cut area in reducing N exports. The buffer zone retained 76% of the N flux coming from the clear-cut area. Nitrification was a key process in controlling the N export after clear-cutting and N increases were mainly as nitrate. Most of the annual N export took place during the spring flood, when uptake of N by plants was minimal

Non-universality of elastic exponents in random bond-bending networks

We numerically investigate the rigidity percolation transition in two-dimensional flexible, random rod networks with freely rotating cross-links. Near the transition, networks are dominated by bending modes and the elastic modulii vanish with an exponent f=3.0\pm0.2, in contrast with central force percolation which shares the same geometric exponents. This indicates that universality for geometric quantities does not imply universality for elastic ones. The implications of this result for actin-fiber networks is discussed.Comment: 4 pages, 3 figures, minor clarifications and amendments. To appear in PRE Rap. Com

CHARACTERISATION AND IN VITRO AND IN VIVO EVALUATION OF SUPERCRITICAL-CO2-FOAMED B-TCP/PLCL COMPOSITES FOR BONE APPLICATIONS

Most synthetic bone grafts are either hard and brittle ceramics or paste-like materials that differ in applicability from the gold standard autologous bone graft, which restricts their widespread use. Therefore, the aim of the study was to develop an elastic, highly porous and biodegradable beta-tricalciumphosphate/poly(L-lactide-co-epsilon-caprolactone) (beta-TCP/PLCL) composite for bone applications using supercritical CO2 foaming. Ability to support osteogenic differentiation was tested in human adipose stem cell (hASC) culture for 21 d. Biocompatibility was evaluated for 24 weeks in a rabbit femur-defect model. Foamed composites had a high ceramic content (50 wt%) and porosity (65-67 %). After 50 % compression, in an aqueous environment at 37 degrees C, tested samples returned to 95 % of their original height. Hydrolytic degradation of beta-TCP/PLCL composite, during the 24-week follow-up, was very similar to that of porous PLCL scaffold both in vitro and in vivo. Osteogenic differentiation of hASCs was demonstrated by alkaline phosphatase activity analysis, alizarin red staining, soluble collagen analysis, immunocytochemical staining and qRT-PCR. In vitro, hASCs formed a pronounced mineralised collagen matrix. A rabbit femur defect model confirmed biocompatibility of the composite. According to histological Masson-Goldner's trichrome staining and micro-computed tomography, beta-TCP/PLCL composite did not elicit infection, formation of fibrous capsule or cysts. Finally, native bone tissue at 4 weeks was already able to grow on and in the beta-TCP/PLCL composite. The elastic and highly porous beta-TCP/PLCL composite is a promising bone substitute because it is osteoconductive and easy-to-use and mould intraoperatively.Peer reviewe

Monitoring the gelation of gellan gum with torsion rheometry and brightness-mode ultrasound

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Gas-foamed poly(lactide-co-glycolide) and poly(lactide-co-glycolide) with bioactive glass fibres demonstrate insufficient bone repair in lapine osteochondral defects

Deep osteochondral defects may leave voids in the subchondral bone, increasing the risk of joint structure collapse. To ensure a stable foundation for the cartilage repair, bone grafts can be used for filling these defects. Poly(lactide-co-glycolide) (PLGA) is a biodegradable material that improves bone healing and supports bone matrix deposition. We compared the reparative capacity of two investigative macroporous PLGA-based biomaterials with two commercially available bone graft substitutes in the bony part of an intra-articular bone defect created in the lapine femur. New Zealand white rabbits (n = 40) were randomized into five groups. The defects, 4 mm in diameter and 8 mm deep, were filled with neat PLGA; a composite material combining PLGA and bioactive glass fibres (PLGA-BGf); commercial beta-tricalcium phosphate (beta-TCP) granules; or commercial bioactive glass (BG) granules. The fifth group was left untreated for spontaneous repair. After three months, the repair tissue was evaluated with X-ray microtomography and histology. Relative values comparing the operated knee with its contralateral control were calculated. The relative bone volume fraction ( increment BV/TV) was largest in the beta-TCP group (pPeer reviewe