Structural Performance of Cold Formed Sections Portal Frames Eave Connections with Different Fasteners (Screws / Bolts)

Recently, there is a growing interest for cold formed sections to be used in low- to mid-rise buildings as primary load carrying structural elements as well as portal frames with short spans. This paper studies the structural behavior of cold formed sections portal frames eave connections under vertical static loads. In the connection details, the beams and columns are connected together via tapered gusset plates. Two types of fasteners are studied which are self-drilling screws and bolts. The beam and column sections are back-to-back lipped channels with web, flange, and lip dimensions are 200mm, 60mm, and 20mm; respectively. Thickness of the sections is kept constant equal to 2mm. Parameters studied are thickness of the gusset plate (2mm, and 3mm). The connections are investigated experimentally as well as numerically using ABAQUS software. In the finite element simulation, 4-noded reduced integration shell elements (S4R) are used for modelling the steel sections, and a bi-linear stress-strain curve is adopted. The material properties are defined based on a tensile coupon test result. Moreover, both bolts and screws are modeled as elastic-rigid fasteners. Mechanical properties of the screw fasteners were defined according to direct shear tests of lap joint with single screw. Results reveal that, experimental as well as numerical findings are comparable. In addition, failure modes are either bearing and screw tilting in the gusset plates or local buckling in the gusset plates. Further, for thick gusset plates, bolted connections exhibit high strength accompanied with small vertical displacements compared with the screw connections.I would like to express my profound thanks to EMCON for their great assistance in the fabrication and installation of the specimens, as well as to HBRC, where all the experimental studies were carried out

Characterization of and structural insight into struvite-K, MgKPO4·6H2O, an analogue of struvite

Struvite-K (MgKPO4·6H2O) is a magnesium potassium phosphate mineral with naturally cementitious properties, which is finding increasing usage as an inorganic cement for niche applications including nuclear waste management and rapid road repair. Struvite-K is also of interest in sustainable phosphate recovery from wastewater and, as such, a detailed knowledge of the crystal chemistry and high-temperature behavior is required to support further laboratory investigations and industrial applications. In this study, the local chemical environments of synthetic struvite-K were investigated using high-field solid-state 25Mg and 39K MAS NMR techniques, alongside 31P MAS NMR and thermal analysis. A single resonance was present in each of the 25Mg and 39K MAS NMR spectra, reported here for the first time alongside the experimental and calculated isotropic chemical shifts, which were comparable to the available data for isostructural struvite (MgNH4PO4·6H2O). An in situ high-temperature XRD analysis of struvite-K revealed the presence of a crystalline–amorphous–crystalline transition that occurred between 30 and 350 °C, following the single dehydration step of struvite-K. Between 50 and 300 °C, struvite-K dehydration yielded a transient disordered (amorphous) phase identified here for the first time, denoted δ-MgKPO4. At 350 °C, recrystallization was observed, yielding β-MgKPO4, commensurate with an endothermic DTA event. A subsequent phase transition to γ-MgKPO4 was observed on further heating, which reversed on cooling, resulting in the α-MgKPO4 structure stabilized at room temperature. This behavior was dissimilar from that of struvite exposed to high temperature, where NH4 liberation occurs at temperatures >50 °C, indicating that struvite-K could potentially withstand high temperatures via a transition to MgKPO4

Cultivation of forage maize in boreal conditions – assessment of trade-offs between increased productivity and environmental impact

The cultivation of whole crop forage maize (Zea mays L.) for cattle feed has a potential for increased forage yield while reducing nitrogen (N) fertilization compared to perennial grass-based systems. However, the possible environmental trade-offs of forage maize cultivation remain unknown in the boreal region due to the short growing season which limits cultivation practices. The aim of this study was to compare the environmental impact of forage maize with more widely cultivated forage crops in Finland that include perennial silage grass mixtures and whole crop spring cereal harvested as silage. The use of plastic mulch film in forage maize cultivation was included in the assessment as well. A life cycle assessment (LCA) was conducted including impact categories for global warming potential; marine and freshwater eutrophication; terrestrial acidification; freshwater, marine and terrestrial ecotoxicity; land use; and fossil resource depletion. Additionally, soil organic carbon (SOC) stock changes under long-term cultivation of the studied forage crops were simulated with the C-TOOL and Yasso20 models with methodological comparisons. The only clear differences between the studied crops were that the land use was lower (-26–48%) for forage maize, and the freshwater eutrophication (+59–67%) and terrestrial acidification (+10–57%) were higher for perennial grasses compared with other forages. A risk for decreased SOC stock under continuous forage maize cultivation was observed. Forage maize could be used to supplement perennial grass cultivation without major associated environmental risks. Future research shall be conducted on the effect of forage choices on the environmental impact of boreal dairy milk production and on decreasing the current high uncertainty associated with nitrous oxide (N2O) emission factors and SOC stock modelling choices

Tephritid fruit fly species composition, seasonality, and fruit infestations in two central African agro-ecological zones

Open Access Journal; Published online: 13 Nov 2022Bactrocera dorsalis and several Africa-native Ceratitis species are serious constraints to fruit production in sub-Saharan Africa. A long-term trapping and fruit collection study was conducted (2011–2016) in two contrasting agro-ecological zones (AEZs) of Cameroon to determine fruit fly species composition, seasonality, attraction to various lures and baits, and fruit infestation levels. Ten tephritid species from genera Bactrocera, Ceratitis, Dacus, and Perilampsis were captured in traps. Bactrocera dorsalis was the most dominant of the trapped species and persisted throughout the year, with peak populations in May–June. Ceratitis spp. were less abundant than B. dorsalis, with Ceratitis anonae dominating in the western highland zone and Ceratitis cosyra in the humid forest zone. Methyl eugenol and terpinyl acetate captured more B. dorsalis and Ceratitis spp., respectively than Torula yeast. The latter was the most effective food bait on all tephritid species compared with Bio- Lure and Mazoferm. Bactrocera dorsalis was the dominant species emerging from incubated fruits, particularly mango, guava, and wild mango. Four plant species—I. wombolu, Dacryodes edulis, Voacanga Africana and Trichoscypha abut—were new host records for B. dorsalis. This study is the first long-duration and comprehensive assessment of frugivorous tephritid species composition, fruit infestations, and seasonality in Central Africa

Dietary Intervention in Infancy and Cognitive Function in Young Adulthood: The Special Turku Coronary Risk Factor Intervention Project

Objective: Consumption of saturated fatty acids (SAFAs), polyunsaturated fatty acids (PUFAs), cholesterol, and fiber have been linked with cognitive function in adults. We evaluated these associations from childhood by leveraging data from the Special Turku Coronary Risk Factor Intervention Project (STRIP).Study design: STRIP recruited children aged 5 months and randomly assigned them into intervention/control groups. The intervention introduced a heart-healthy diet, characterized mainly by low consumption of SAFAs and cholesterol, through counseling at least biannually between age 7 months and 20 years. Diet was assessed repeatedly using food diaries. Six years after the end of the intervention phase, at age 26 years, the participants were invited to the first postintervention follow-up, which included cognitive testing that covered learning and memory, verbal memory, short-term working memory, reaction time, information processing, and cognitive flexibility and inhibitory control. We studied the associations of the STRIP intervention and the consumptions of SAFAs, PUFAs, cholesterol, and fiber within these cognitive domains.Results: Participants in the STRIP intervention group had better cognitive flexibility and inhibitory control and were better able to manage conflicting information and ignore task-irrelevant information (0.18 SD higher in the intervention group, adjusted for sex and socioeconomic status). No associations were observed with the dietary components studied.Conclusions: The infancy-onset STRIP intervention, which promoted a heart-healthy diet, was favorably associated with cognitive flexibility and inhibitory control at age 26 years. No associations were found for the intervention targets studied, indicating that these specific dietary components did not underlie the observed effect of the intervention.</p

Spin-Charge Separation in the t−Jt-J Model: Magnetic and Transport Anomalies

A real spin-charge separation scheme is found based on a saddle-point state of the $t-J$ model. In the one-dimensional (1D) case, such a saddle-point reproduces the correct asymptotic correlations at the strong-coupling fixed-point of the model. In the two-dimensional (2D) case, the transverse gauge field confining spinon and holon is shown to be gapped at {\em finite doping} so that a spin-charge deconfinement is obtained for its first time in 2D. The gap in the gauge fluctuation disappears at half-filling limit, where a long-range antiferromagnetic order is recovered at zero temperature and spinons become confined. The most interesting features of spin dynamics and transport are exhibited at finite doping where exotic {\em residual} couplings between spin and charge degrees of freedom lead to systematic anomalies with regard to a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic fluctuation with a small, doping-dependent energy scale is found, which is characterized in momentum space by a Gaussian peak at ($\pi/a$, $\pi/a$) with a doping-dependent width ($\propto \sqrt{\delta}$, $\delta$ is the doping concentration). This commensurate magnetic fluctuation contributes a non-Korringa behavior for the NMR spin-lattice relaxation rate. There also exits a characteristic temperature scale below which a pseudogap behavior appears in the spin dynamics. Furthermore, an incommensurate magnetic fluctuation is also obtained at a {\em finite} energy regime. In transport, a strong short-range phase interference leads to an effective holon Lagrangian which can give rise to a series of interesting phenomena including linear-$T$ resistivity and $T^2$ Hall-angle. We discuss the striking similarities of these theoretical features with those found in the high-$T_c$ cuprates and give aComment: 70 pages, RevTex, hard copies of 7 figures available upon request; minor revisions in the text and references have been made; To be published in July 1 issue of Phys. Rev. B52, (1995

D* Production in Deep Inelastic Scattering at HERA

This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+$ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.Comment: 17 pages including 4 figure

Observation of Scaling Violations in Scaled Momentum Distributions at HERA

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of $x$ and $Q^2$ using the ZEUS detector. The evolution of the scaled momentum, $x_p$, with $Q^2,$ in the range 10 to 1280 $GeV^2$, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of $Q^2$.Comment: 21 pages including 4 figures, to be published in Physics Letters B. Two references adde

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Attainment of Targets of the 20-Year Infancy-Onset Dietary Intervention and Blood Pressure Across Childhood and Young Adulthood The Special Turku Coronary Risk Factor Intervention Project (STRIP)

We examined whether success in achieving the key targets of an infancy-onset 20-year dietary intervention was associated with blood pressure (BP) from infancy to young adulthood. In the prospective randomized STRIP (Special Turku Coronary Risk Factor Intervention Project; n=877 children), dietary counseling was provided biannually based on the Nordic Nutrition Recommendations primarily to improve the quality of dietary fat in children's diets and secondarily to promote intake of vegetables, fruits, and whole grains. Dietary data and BP were accrued annually from the age of 13 months to 20 years. The dietary targets for fat quality were defined as the ratio of saturated fatty acids to monounsaturated and polyunsaturated fatty acids <1:2 and intake of saturated fatty acids <10 E%, dietary fiber intake in the top age-specific quintile, and dietary sucrose intake as being in the lowest age-specific quintile. Attaining a higher number of the dietary targets was associated with lower systolic BP (mean [SE] systolic BP, 107.3 [0.3], 107.6 [0.3], 106.8 [0.3], and 106.7 [0.5] mm Hg in participants meeting 0, 1, 2, and 3 to 4 targets, respectively;P=0.03) and diastolic BP (mean [SE] diastolic BP, 60.4 [0.2], 60.5 [0.2], 59.9 [0.2], and 59.9 [0.3] mm Hg;P=0.02). When the lowest age-specific quintile of dietary cholesterol was added as an additional target, the association with systolic BP remained significant (P=0.047), but the association with diastolic BP attenuated (P=0.13). Achieving the key targets of an infancy-onset 20-year dietary intervention, reflecting dietary guidelines, was favorably albeit modestly associated with systolic and diastolic BP from infancy to young adulthood