Parallel and Cross-Sectional Hamstring Injuries in Sprint Running

This issue of Journal of Sport and Health Science contains a point-counterpoint discussion of hamstring injuries in sprint running by the groups of Drs. Liu and Yu.1–4 They propose different mechanisms of muscle injuries in general, and hamstring injuries in sprint running specifically. Yu et al.2,4 present evidence suggesting that hamstring injuries are primarily caused by excessive muscle strain during eccentric contraction. In maximal effort sprint running, excessive muscle strains occur at the end of the swing phase. In contrast, Liu et al.1,3 point out that, in addition to excessive hamstring strain, high stresses in the late swing and early stance phase and the transition between swing and stance may also contribute to hamstring injuries when the hamstrings actively assist hip extension and knee flexion. Both groups provide supporting published, scientific evidence for their contention. Yet, the entire discussion is based on the assumption that the hamstring muscles contract uniformly in all phases of sprint running. However, the different heads of the hamstring muscles have different insertion sites, structure, and fiber type distributions. Therefore, it is safe to assume that the individual heads fulfill different functions and that they do not elongate at the same rate and that stress across them is not uniform. Using magnetic resonance imaging in combination with finite element modeling, Fiorentino and colleagues5 reported that non-uniformity in fiber strains may also be a contributing factor for hamstring injuries, especially when sprinting at high speeds. We propose that this fiber strain and strain rate non-uniformity at fast sprint speeds could lead to “parallel injury”, tissue separation, and misalignment of myofibrils along the muscle fibers (e.g., see Lee and Healy, 2012, for a detailed image6). Along these lines, Morgan7 proposed the so-called “Popping Sarcomeres Hypothesis”, which is based on the idea that repeated high stresses during eccentric contractions leads to “tearing” of sarcomeres, and the local damage of sarcomeres leads to more damage in adjacent sarcomeres and neighboring myofibrils due to the sudden increase in localized stress. We propose that the “Popping Sarcomeres” phenomenon could lead to “cross-sectional” hamstring injuries in which the damage occurs tangential to the fiber orientation and produces disruptions of the Z-lines and misaligned A-bands (see Morgan, 1990, for exemplar image7). Parallel and cross-sectional hamstring injuries may have different underlying causes and may provide a post hoc possibility for evaluating how the injury occurred. In severe hamstring injuries (Grade II or more), one might expect simultaneous parallel and cross-sectional injuries. The detailed mechanisms of hamstring injuries in sprint running remain a question of debate, and it might be time to look at this issue from an altogether different point of view. Considering that hamstring strains and strain rates might be non-uniform across the different heads, it appears feasible that the non-uniform strains and strain rates may lead to “parallel” injuries, whereas non-uniform stresses might lead to “cross-sectional” injuries. Considering different and multiple hamstring muscle injury mechanisms in sprint running may lead to more targeted training strategies and provide new insights into the prevention and rehabilitation of hamstring injuries

Torrefaction of Conservation Reserve Program biomass: a techno-economic evaluation

The Conservation Reserve Program (CRP), which was initiated to prevent soil erosion, provides a large amount of cellulosic biomass that is potentially useful for bioenergy production. We investigated the effects of torrefaction conditions on the physicochemical properties of CRP biomass using an elemental analyzer, a thermogravimetric analyzer, and a calorimeter. Results suggest that the upgraded biomass is a hydrophobic, high-energy density, and low-moisture-content material. The study on biomass polymer composition showed how polymer components changed with processing conditions. The polysaccharides in biomass were degraded significantly at 300 °C, suggesting that processing conditions should be managed properly for sugar or energy recovery. Our economic analysis suggested that the processing cost for a torrefaction plant with an annual capacity of 100,000 tons of CRP biomass is $16.3 per ton of feedstock. Further analysis of the effects of torrefaction on the biomass supply chain suggested that processing could save pelletization and transportation costs

Lattice Boltzmann Simulations of Thermal Convective Flows in Two Dimensions

In this paper we study the lattice Boltzmann equation (LBE) with multiple-relaxation-time (MRT) collision model for incompressible thermo-hydrodynamics with the Boussinesq approximation. We use the MRT thermal LBE (TLBE) to simulate the following two flows in two dimensions: the square cavity with differentially heated vertical walls and the Rayleigh-Benard convection in a rectangle heated from below. For the square cavity, the flow parameters in this study are the Rayleigh number Ra = 103-106, and the Prandtl number Pr = 0.71; and for the Rayleigh-Benard convection in a rectangle, Ra = 2 . 103, 104 and 5 . 104, and Pr = 0.71 and 7.0

The Effect of Gasification Conditions on the Surface Properties of Biochar Produced in a Top-Lit Updraft Gasifier

The effect of airflow rate, biomass moisture content, particle size, and compactness on the surface properties of biochar produced in a top-lit updraft gasifier was investigated. Pine woodchips were studied as the feedstock. The carbonization airflow rates from 8 to 20 L/min were found to produce basic biochars (pH > 7.0) that contained basic functional groups. No acid functional groups were presented when the airflow increased. The surface charge of biochar at varying airflow rates showed that the cation exchange capacity increased with airflow. The increase in biomass moisture content from 10 to 14% caused decrease in the pH from 12 to 7.43, but the smallest or largest particle sizes resulted in low pH; therefore, the carboxylic functional groups increased. Similarly, the biomass compactness exhibited a negative correlation with the pH that reduced with increasing compactness level. Thus, the carboxylic acid functional groups of biochar increased from 0 to 0.016 mmol g−1, and the basic functional group decreased from 0.115 to 0.073 mmol g−1 when biomass compactness force increased from 0 to 3 kg. BET (Brunauer-Emmett-Teller) surface area of biochar was greater at higher airflow and smaller particle size, lower moisture content, and less compactness of the biomassThe effect of airflow rate, biomass moisture content, particle size, and compactness on the surface properties of biochar produced in a top-lit updraft gasifier was investigated. Pine woodchips were studied as the feedstock. The carbonization airflow rates from 8 to 20 L/min were found to produce basic biochars (pH > 7.0) that contained basic functional groups. No acid functional groups were presented when the airflow increased. The surface charge of biochar at varying airflow rates showed that the cation exchange capacity increased with airflow. The increase in biomass moisture content from 10 to 14% caused decrease in the pH from 12 to 7.43, but the smallest or largest particle sizes resulted in low pH; therefore, the carboxylic functional groups increased. Similarly, the biomass compactness exhibited a negative correlation with the pH that reduced with increasing compactness level. Thus, the carboxylic acid functional groups of biochar increased from 0 to 0.016 mmol g−1, and the basic functional group decreased from 0.115 to 0.073 mmol g−1 when biomass compactness force increased from 0 to 3 kg. BET (Brunauer-Emmett-Teller) surface area of biochar was greater at higher airflow and smaller particle size, lower moisture content, and less compactness of the biomas

Control of antiviral innate immune response by protein geranylgeranylation

The mitochondrial antiviral signaling protein (MAVS) orchestrates host antiviral innate immune response to RNA virus infection. However, how MAVS signaling is controlled to eradicate virus while preventing self-destructive inflammation remains obscure. Here, we show that protein geranylgeranylation, a posttranslational lipid modification of proteins, limits MAVS-mediated immune signaling by targeting Rho family small guanosine triphosphatase Rac1 into the mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) at the mitochondria-ER junction. Protein geranylgeranylation and subsequent palmitoylation promote Rac1 translocation into MAMs upon viral infection. MAM-localized Rac1 limits MAVS\u27 interaction with E3 ligase Trim31 and hence inhibits MAVS ubiquitination, aggregation, and activation. Rac1 also facilitates the recruitment of caspase-8 and cFLIPL to the MAVS signalosome and the subsequent cleavage of Ripk1 that terminates MAVS signaling. Consistently, mice with myeloid deficiency of protein geranylgeranylation showed improved survival upon influenza A virus infection. Our work revealed a critical role of protein geranylgeranylation in regulating antiviral innate immune response

Adhesive performance of camelina protein affected by extraction conditions

Citation: Qi, G., Li, N., Sun, X. S., & Wang, D. (2016). Adhesive performance of camelina protein affected by extraction conditions. Transactions of the Asabe, 59(3), 1083-1090. doi:10.13031/trans.59.11686Camelina protein (CP) adhesives were prepared from de-hulled camelina meal using alkaline solubilization (CP 8, CP 9, CP 10, CP 11, CP 12) and isolelectric precipitation. CP 12 had the highest protein yield with 46.22%, more than twice that of CP 8 (22.71%), indicating that extreme alkaline pH is necessary for high camelina protein solubility and protein yield. Extreme alkalinization resulted in severe molecular dissociation of camelina protein, as indicated by the appearance of a low molecular weight band (20 kDa). Compared to CP 8, CP 9, CP 10, and CP 11, CP 12 had a completely denatured protein structure with greater amounts of exposed functional groups, which is beneficial to the adhesion strength of CP 12. CP 12 with 9% sodium chloride treatment demonstrated optimum adhesion performance with dry and wet strengths of 4.36 and 1.36 MPa, respectively, compared to 3.37 and 1.05 MPa for CP 12 without sodium chloride treatment. © 2016 American Society of Agricultural and Biological Engineers

Bioconversion of industrial hemp biomass for bioethanol production: A review

Industrial hemp (Cannabis sativa L.) with robust drought-resistant features has excellent agronomic and pharmaceutical characteristics. As the federal prohibition on hemp cultivation was lifted, its valorization in various aspects is highly required. This review aims to summarize the potential of hemp biomass for bioethanol production. Chemical compositions of hemp biomass were evaluated as compared with those of corn fiber, corn stover, and sorghum bagasse. Several representative pretreatment technologies used for hemp biomass were summarized in terms of sugar recoveries, lignin removal, and sugar and ethanol yields. This review presents numerous technical barriers attributed to insufficient fermentable sugar and ethanol concentration during the conversion processes. Also, innovative research approaches (pretreatment optimization, co-fermentation of hexose and pentose, increasing potential sugar loading) in overcoming these challenges were critically reviewed. This review would promote future research on the utilization of hemp biomass for biofuel applications