Search Results (39)

Climate change profoundly impacts the health, productivity, and resilience of forest ecosystems and threatens the sustainability of forest products and wood-based industries. Innovations to enhance tree growth, development, and adaptation offer unprecedented opportunities to strengthen ecosystem resilience and mitigate the effects of climate change. Here, we established a method for protoplast isolation, purification, and CRISPR-Cas ribonucleoprotein (RNP) delivery in Pinus taeda and Abies fraseri as a step towards accelerating the genetic improvement of these coniferous tree species. In this system, purified protoplasts could be isolated from somatic embryos with up to 2 × 10⁶ protoplasts/g of tissue and transfected with proteins and nucleotides, achieving delivery efficiencies up to 13.5%. The delivery of functional RNPs targeting phenylalanine ammonia lyase in P. taeda and phytoene desaturase in A. fraseri yielded gene editing efficiencies that reached 2.1% and 0.3%, respectively. This demonstration of RNP delivery for DNA-free genome editing in the protoplasts of P. taeda and A. fraseri illustrates the potential of CRISPR-Cas to enhance the traits of value in ecologically and economically important tree species. The editing system provides a foundation for future efforts to regenerate genome-edited forest trees to improve ecosystem health and natural resource sustainability. Full article

Subsea wellheads and Christmas trees are commonly utilized in deepwater oil and gas development. However, the special structure of subsea wellheads makes it difficult to monitor casing–casing annular pressure buildup, which in turn poses a greater risk to the integrity of the wellbore. In order to analyze the effect of changes in the casing-free section and the sealed section on the variation in annulus volume, a new annular pressure buildup model of casing-cement sheath-formation deformation was established and verified according to the elastic deformation theory. Furthermore, the influence of casing deformation on annulus pressure buildup was analyzed. Results indicate that the error of annulus pressure buildup predicted by the multi-string mechanical model proposed in this paper that considers the deformation of the casing sealing section is approximately 13% lower than the one that does not consider this factor. This paper provides guidance for the design of casing strings in deepwater oil and gas wells, ensuring safe production. Full article

Common ragweed (Ambrosia artemisiifolia L.) is an extremely competitive broadleaved summer annual weed found in Christmas tree production systems within Michigan. Common ragweed has been reported to have resistance to glyphosate, PSII inhibitors, PPO inhibitors, and ALS herbicides. There have been reports from Michigan Christmas tree growers of common ragweed resistance to clopyralid, a synthetic auxin herbicide, in Montcalm County, Michigan. The objective of this study was to test alternative post-emergence herbicide combinations and organic mulch on clopyralid-resistant common ragweed for weed control efficacy. The following two stages of common ragweed were used: stage 1 (6–9 leaves) and stage 2 (12–14 leaves). For common ragweed in stage 1 in 2021 and 2022, as well as stage 2 in 2022, at all evaluation dates, mulch + clopyralid + oxyfluorfen provided the highest level of weed control. For stage 1 in 2022, this treatment combination provided 100% control from 2 weeks after treatment (WAT) and always showed better or equal weed control compared to all the other treatments. The combination of mulch + clopyralid + glyphosate provided 100% control by 2 WAT when plants were treated at stage 2 in 2022. For the plants treated at stage 1 in 2022, many of the treatments reached a fresh weight of 0 g, but in 2021, those same treatments resulted in a fresh weight of around 20 g. Based on fresh weight, the greatest plant growth occurred with glyphosate treatment in 2021 and clopyralid and mulch alone in 2022. This is likely due to common ragweed’s resistance to these herbicides. Full article

A study was conducted to identify balsam fir (Abies balsamea) for use in Christmas tree breeding programs in Northeastern North America. A total of sixty-four phenotypically good trees were identified from a provincial clonal seed orchard in New Brunswick, a multi-aged natural seed production area in Nova Scotia, and an operational plantation in Quebec, Canada. Trees were selected for good growth and form, numbers, and vigour of internodal branches, acceptable crown taper, needle colour, age class, branch angle, needle configuration, and freedom from insects and diseases or deformities, all traits deemed desirable in a Christmas tree. Three branches from each tree were collected at two harvest dates each year, one early and one late during the normal harvesting season in 2020, 2021, and 2022. Qualitative assessments of colour and branch pliability were performed weekly in conjunction with needle loss rub tests. A quantitative assessment of moisture loss was conducted weekly by measuring branch weights. The combination of qualitative and quantitative assessments was used to identify 7 of the 64 trees for which one or more tested branches consistently remained green and pliable, retained the majority of their needles, and lost moisture at a significantly reduced rate in all six testing periods. Grafts of the seven ‘Select’ trees are currently being integrated into seed orchards in the three participating provinces. These second-generation seed orchards are part of breeding programs designed to develop Christmas trees that will perform well under warm fall conditions, an outcome of climate change. The results from this study combined with the progeny testing of the ‘Select’ trees will be used to test for the heritability of needle retention, a key trait for the next generation of Christmas trees in the Northeast. Full article

The subsea jumper has become an essential part of subsea production systems as a gas–liquid mixing pipeline connecting the pipeline end manifold (PLEM) to the Christmas tree. During oil and gas transportation, as a common flow pattern, the alternating flow characteristics of the slug flow easily cause pipeline vibration, resulting in pipeline instability or fatigue damage. The present study investigates experimentally and numerically the slug flow characteristics in the subsea M-shaped jumper and its induced vibrations of the jumper. The flow pattern evolution and slug characteristics of the inner slug flow under different gas–liquid velocities are obtained: the slug frequency and slug velocity, as well as the pressure fluctuation and vibration characteristics caused by the slug flow. The results show that the pressure fluctuations in the front and rear parts of the M-type jumper are obviously different. With the increase in the air–water mixing, the two characteristics, the slug frequency, and the slug velocity also increase. The gas velocity has a greater influence on the slug frequency than the liquid velocity. The slug length decreases as the slug frequency increases. Furthermore, numerical simulations under various experimental conditions are carried out. The results show that the simulation results of the pressure data, the slug characteristics, and the induced vibration amplitude are in good agreement with the experimental data. Full article

Underwater pressure-bearing structures are produced in practice by means of pressure self-enhancement methods in order to improve the stress distribution and enhance the pressure-bearing performance. On the other hand, the pairs equation shows that stress is an important factor influencing the degradation of the structure. In fact, improving the stress distribution will not only improve the pressure-bearing performance, but will have an impact on the life degradation trend. Thus, pressure self-enhancement affects the structural life by changing the stress distribution. With this in mind, this paper considers the effect of pressure self-enhancement on the service time of subsea structures, and a Bayesian network (BN)-based method that can be used to predict the remaining useful life (RUL) of underwater self-enhanced structures is proposed. The method also takes into account the influence of multiple sources of structural factors in order to predict the RUL of the structure more accurately. The life degradation process of an all-electric Christmas tree valve actuator is used as a case study. The prediction results are compared with data in the literature to verify the validity of the method. The results have implications for guidance on the O&M assurance of underwater production systems. Full article

Weed control is an important aspect during the first few years of Christmas tree establishment, as weed competition directly relates to the rate of Christmas tree growth during this time. The objectives of this study were to evaluate the weed control efficacy of organic mulch and herbicide combinations and to determine their phytotoxic effects on four different species of Christmas trees during the establishment stage: Fraser fir (Abies fraseri (Pursh) Poir), blue spruce (Picea pungens Engelm.), white pine (Pinus strobus L.), and Scotch pine (Pinus sylvestris L.). Twelve weed control treatments were established in a complete randomized block design with four replications in each of five fields. Weed control treatments included cypress bark organic mulch and herbicides applied alone and in combinations as well as an untreated control. Herbicides included clopyralid, oxyfluorfen, and glyphosate. All herbicides were applied at their highest labeled rate. Data collection included visual estimations of weed control and phytotoxicity to trees at 30, 60, and 90 days after treatment (DAT). Tree growth and foliar nitrogen concentration were also measured. Mulch combined with herbicide provided 60%–100% weed control in all cases; at two farms, mulch provided a significant increase in weed control when compared to the same treatments without mulch. Combinations of mulch + clopyralid + glyphosate and clopyralid + oxyfluorfen + glyphosate resulted in the highest phytotoxicity ratings. Tree growth was decreased due to some treatments at Gobles farm, and foliar N did not differ among any of the treatments. Full article

Somatic embryogenesis (SE) cloning techniques for Nordmann fir Christmas tree production have been pursued and refined in Denmark, and three SE clonal trials with 201 SE clones from seeds of 27 Nordmann fir trees and seedlings from bulk harvest seeds in Georgia, Caucasus, were established from 2014 to 2015. This study was the first to evaluate the genetic performance of these SE clones in different sites. In addition, the performance of SE clones and (zygotic) normal seedlings in the field was compared in this study. This study was based on three key groups of traits for Christmas tree production, measured 5 and 6 years after planting: growth, commercial tree quality, and disorder. Seedlings grew faster and had better Christmas tree quality than SE clones. There were significant family effects for all traits, indicating that a good family also produced good clones on average. Growth and disorder traits were under moderate genetic control, with estimated broad-sense heritability (H²) from 0.19 to 0.31 and from 0.20 to 0.28, respectively. Quality traits had low to moderate H², ranging from 0.09 to 0.24. Significant genotype-by-environment interactions were shown for Christmas tree quality, post-harvest needle retention, and branch angle, suggesting the importance of choosing the right clone at each site. There was no significant interaction in height among the years. Superior clones, compared to the unbred seed source, were identified by combining several important traits. Overall, the somatic clones were well established but had slower growth compared to standard seedlings. Full article

Most mechanical components are subject to dynamic loads, which can cause failure in service. This study aims to evaluate the effect of variable amplitude loadings on fatigue crack growth (FCG) in CT specimens produced with the AA2024-T351 aluminum alloy. Specifically, it is intended to predict the FCG rate when the specimen is subjected to a complex loading pattern, named the “Christmas Tree Spectrum”. Crack growth is simulated by node release, which occurs when the cumulative plastic strain at the crack tip reaches a critical value (110%) that is supposed to be a material property. It is therefore assumed that cyclic plastic deformation is the main damage mechanism. The specimen was subjected to four different load patterns: the 6–60 N low-frequency constant amplitude load (CAL); the 6–21 N high-frequency CAL; the Christmas Tree (15–9) and the Christmas Tree (9–3) patterns. The Christmas Tree 15–9 load pattern is defined by nine increments of +15 N and −9 N followed by eight increments of +9 N and −15 N. The results indicate that the Christmas Tree (15–9) pattern increases crack tip damage relative to the constant amplitude loading. This is attributed to small variations in material hardening, particularly during the unloading phase of the load block. On the other hand, the Christmas Tree (9–3) pattern did not show a significant effect, indicating the importance of the range of small-amplitude cycles. The crack closure phenomenon is usually used explain the effect of loading parameters, but this is an exception. Full article

Early cone formation is a consistent issue in Fraser fir Christmas tree plantations in the eastern United States. Growers must remove cones by hand, resulting in significant labor costs, as cones degrade the aesthetic value of Christmas trees. In this study, we conducted two series of experiments in collaboration with several Christmas tree farms to determine the effectiveness of applying plant growth regulators (PGRs), specifically GA-inhibitors, in reducing cone formation and shoot growth in Fraser fir. In the first experiments we investigated the effectiveness of paclobutrazol, applied as a soil injection or as a foliar spray in reducing cone formation. The highest rate of soil application (300 mL of paclobutrazol per tree) reduced cumulative coning by approximately 38%. Leader growth control of soil applied paclobutrazol increased with application rate. In the second set of experiments, we compared four GA-inhibitors (paclobutrazol, chlormequat chloride, uniconazole-p, daminozide) applied as foliar sprays on coning and leader growth. Overall, paclobutrazol was the most effective compound for reducing coning and shoot growth. The results confirm earlier findings that application of GA-inhibitors can reduce, but not eliminate, coning. Likewise, PGR application can reduce shoot growth and possibly increase tree density but will not eliminate the need for shearing. Full article

Microfluidic gradient generators (MGGs) provide a platform for investigating how cells respond to a concentration gradient or different concentrations of a specific chemical. Among these MGGs, those based on Christmas-tree-like structures possess advantages of precise control over the concentration gradient profile. However, in designing these devices, the lengths of channels are often not well considered so that flow rates across downstream outlets may not be uniform. If these outlets are used to culture cells, such non-uniformity will lead to different fluidic shear stresses in these culture chambers. As a result, cells subject to various fluidic stresses may respond differently in aspects of morphology, attachment, alignment and so on. This study reports the rationale for designing Christmas-tree-like MGGs to attain uniform flow rates across all outlets. The simulation results suggest that, to achieve uniform flow rates, the lengths of vertical channels should be as long as possible compared to those of horizontal channels, and modifying the partition of horizontal channels is more effective than elongating the lengths of vertical channels. In addition, PMMA-based microfluidic chips are fabricated to experimentally verify these results. In terms of chemical concentrations, perfect linear gradients are observed in devices with modified horizontal channels. This design rationale will definitely help in constructing optimal MGGs for cell-based applications including chemotherapy, drug resistance and drug screening. Full article

Inductive wireless power transfer systems often incorporate unconventional, irregularly shaped transmitter windings for the purposes of covering a designated area, fitting into special enclosures and enhancing the tolerance of misalignment. To design and optimise the winding structures, the inductive parameters must be extracted and linked to the design objectives. Conventionally, these parameters can be extracted using three-dimensional finite element analysis, which often requires subjective manual tweaks and prolonged trial and error procedures. The efficacy is therefore greatly dependent on the experience of the designer. In this paper, a case study for modelling and optimising the spatial coverage by scuplturing the winding shape is demonstrated via a Christmas tree model, utilising the parametric formation equations and line-integral based numerical solvers. A cone-shaped winding with variable interturn pitches was used as the transmitter and a receiver winding was designed to be fit into a bubble that can be hung on the tree. A two-stage optimisation method with simplified degree-of-freedom parameters and brutal force search was used to find the optimal design candidate. Heatmaps of receiver output voltages were generated in a time-efficient way, intuitively helping the designers to make adjustments for the winding structures. A practical prototype was built to verify the open loop voltage distribution on the receiving winding at various positions and another demonstration was made to show the continuum of power coverage around the Christmas tree. Full article

According to the American Cancer Society, roughly 54,000 new cases of oral cavity or oropharyngeal cancers have been detected in the United States of America in 2021, and they will cause about 10,850 deaths. The main therapies for cancer management, such as surgery and radio- and chemotherapy, have some own benefits, albeit they are often destructive for surrounding tissues; thus, deep investigations into non-surgical treatments for oral cavities are needed. Biologically active compounds (BACs) extracted from European Spruce needles were analyzed to determine the total phenolic and flavonoid content and were used as additional ingredients for oral hygiene products. An anti-proliferation investigation was carried out using extracts containing BACs with the use of several cell lines (cancer and a normal one). ESI-MS studies on BACs showed that luteolin, a natural flavonoid compound with anti-tumorigenic properties against various types of tumors, is the predominant component of the extracts. MTT, BrdU, and LIVE/DEAD studies demonstrated that BAC extracts obtained from Christmas tree needles possess anticancer properties against squamous cell carcinoma (with epithelial origins). We proved that BAC extracts contain high amounts of luteolin, which induces cytotoxicity toward cancer cells; along with their high selectivity, robustness, and nontoxicity, they are very promising materials in oral health applications. Full article

This systematic review aimed to analyze the development and functionality of microfluidic concentration gradient generators (CGGs) for toxicological evaluation of different biological organisms. We searched articles using the keywords: concentration gradient generator, toxicity, and microfluidic device. Only 33 of the 352 articles found were included and examined regarding the fabrication of the microdevices, the characteristics of the CGG, the biological model, and the desired results. The main fabrication method was soft lithography, using polydimethylsiloxane (PDMS) material (91%) and SU-8 as the mold (58.3%). New technologies were applied to minimize shear and bubble problems, reduce costs, and accelerate prototyping. The Christmas tree CGG design and its variations were the most reported in the studies, as well as the convective method of generation (61%). Biological models included bacteria and nematodes for antibiotic screening, microalgae for pollutant toxicity, tumor and normal cells for, primarily, chemotherapy screening, and Zebrafish embryos for drug and metal developmental toxicity. The toxic effects of each concentration generated were evaluated mostly with imaging and microscopy techniques. This study showed an advantage of CGGs over other techniques and their applicability for several biological models. Even with soft lithography, PDMS, and Christmas tree being more popular in their respective categories, current studies aim to apply new technologies and intricate architectures to improve testing effectiveness and reduce common microfluidics problems, allowing for high applicability of toxicity tests in different medical and environmental models. Full article

Balsam fir needle retention and fatty acid profile changes due to cold acclimation throughout autumn, but little is known about the relationship between these two phenomena. The objective was to examine differences in FAs in contrasting needle abscission resistant balsam fir genotypes throughout autumn and early winter. Branches from genotypes with low and high needle abscission resistance (NAR) were collected from September to January and analyzed for FA composition. High NAR genotypes retained needles 120–130% longer than low NAR genotypes and NAR increased through autumn in both genotypes. There was approximately a 3:1 ratio of unsaturated: saturated FAs, which increased by 4% in favor of unsaturated fatty acids through autumn. Palmitic, palmitoleic, and linolenic acid content was significantly higher in high NAR versus low NAR genotypes; arachidic, oleic, linoleic, pinolenic, coniferonic, icosadienoic, and sciadonic acids were lower in high NAR genotypes versus low. Linolenic acid was of particular interest because it tended to decrease throughout autumn, to the point that high NAR genotypes were significantly lower in linolenic acid than low NAR genotypes in January. These changes may be linked to an increase in abscisic acid and/or jasmonic acid synthesis depleting linolenic acid stores and promoting postharvest needle abscission resistance. Full article