A size-dependent functionally graded piezoelectric beam model is developed using a variational formulation. It is based on the modified strain gradient theory and Timoshenko beam theory. The material ...properties of functionally graded piezoelectric beam are assumed to vary through the thickness according to a power law. The new model contains three material length scale parameters and can capture the size effect, unlike the classical beam theory. To illustrate the new functionally graded piezoelectric beam model, the static bending and free vibration problems of a simply supported beam are numerical solved. These results may be useful in the analysis and design of smart structures constructed from piezoelectric materials.
BACKGROUND: Lateral spinous process deviation (LSPD) is a commonly used morphologicalparameter in the anatomical study of the cervical spinous process.However, quantitative studies on this issue are ...still lacking. In this study we aimedto establish reference intervals of C2-C7 LSPD in the adult Chinese population andprovide decision-making information for clinical practitioners. MATERIALS AND METHODS: This was a retrospective study of 92 adult patientswho received neck computed tomography scans, including 42 females and50 males meeting the inclusion criteria. Three-dimensional reconstruction andanatomical measurements were performed using Mimics Research 19.0 and3-Matic Research 11.0. RESULTS: The inter-observer reliability of LSPD measurement in this study wasexcellent (intraclass correlation coefficient value > 0.93). Only 2 cases of LSPDangles of 90 degrees were found, which means most cervical spinous process existdeviation. The reference interval for the C2-C7 LSPD angle was (85.11, 94.75)degrees. The C2 LSPD showed the different directions to C5 and C7 (p < 0.05).In the C4 vertebrae, the male tends to have greater LSPD angles than the female(T = –2.013, p = 0.047). In the C2 vertebrae, there was a statistically significant butweak correlation between age and LSPD angles (r = 0.24, p = 0.029). There wasno statistically significant effect of sex or age on other levels of cervical vertebrae. CONCLUSIONS: Cervical spinous process deviation of less than 5 degrees on eitherside is a common morphological manifestation in Chinese adults. Thus, LSPD maynot be an indicator for clinical care. Moreover, the vertebrae may have oppositedirections of LSPD in the upper levels (C2-C4) and lower levels (C5-C7).
Abstract
Objectives
To compare the short-term outcomes of unilateral biportal endoscopic lumbar interbody fusion (BLIF) and uniportal endoscopic lumbar interbody fusion (ULIF).
Methods
Sixty patients ...diagnosed with L4/5 spinal stenosis who underwent BLIF and ULIF were included (30 in each group). Clinical evaluation was performed preoperatively and postoperatively in the 1st week, 1st month, and 1st year. Factors such as the visual analogue score (VAS), Oswestry Disability Index (ODI), operative time, surgical complications, and radiological outcomes (fusion rate, screw loosening, and cage subsidence) were compared between the two groups.
Results
All patients showed improved mean VAS and ODI at all three postoperative follow-ups, and no statistically significant differences were detected between the BLIF and ULIF groups. The mean operative time in the BLIF group was shorter than that in the ULIF group. Nerve root injury occurred in two patients in the BLIF group, while leakage of cerebrospinal fluid occurred in one patient in the ULIF group. All adverse events were treated adequately prior to discharge. The fusion rates with definite and probable grades were significantly higher in the BLIF group than that in the ULIF group. One case of cage subsidence with no screw loosening occurred in each group.
Conclusion
Both BLIF and ULIF are safe and effective surgical techniques. Compared with ULIF, BLIF has the advantages of shorter operative time and a higher fusion rate. Other merits of BLIF include a wider surgical field, greater maneuverability of instruments, visibility during cage implantation, and transverse orientation of the cage.
We study the process e^{+}e^{-}→Λ_{c}^{+}Λover ¯_{c}^{-} at twelve center-of-mass energies from 4.6119 to 4.9509 GeV using data samples collected by the BESIII detector at the BEPCII collider. The ...Born cross sections and effective form factors (|G_{eff}|) are determined with unprecedented precision after combining the single and double-tag methods based on the decay process Λ_{c}^{+}→pK^{-}π^{+}. Flat cross sections around 4.63 GeV are obtained and no indication of the resonant structure Y(4630), as reported by Belle, is found. In addition, no oscillatory behavior is discerned in the |G_{eff}| energy dependence of Λ_{c}^{+}, in contrast to what is seen for the proton and neutron cases. Analyzing the cross section together with the polar-angle distribution of the Λ_{c}^{+} baryon at each energy point, the moduli of electric and magnetic form factors (|G_{E}| and |G_{M}|) are extracted and separated. For the first time, the energy dependence of the form factor ratio |G_{E}/G_{M}| is observed, which can be well described by an oscillatory function.
Mirror‐mode structures are widely observed in space plasma environments. Although plasma features within the structures have been extensively investigated in theoretical models and numerical ...simulations, relatively few observational studies have been made, due to a lack of high‐cadence measurements of particle distributions in previous space missions. In this work, electron dynamics associated with mirror‐mode structures are studied based on Magnetospheric Multiscale observations of electron pitch angle distributions. We define mirror‐mode peaks/troughs as the region where the magnetic field strength is greater/smaller than the mean field. The observations show that most electrons are trapped inside the mirror‐mode troughs and display a donut‐like pitch angle distribution configuration. Besides the trapped electrons in mirror‐mode troughs, we find that electrons are also trapped between ambient mirror‐mode peaks and coexisting untrapped electrons within the mirror‐mode structure. Analysis shows that the observed donut‐like electron distributions are the result of betatron cooling and the spatial dependence of electron pitch angles within the structure.
Key Points
Electron PADs of magnetosheath mirror modes are observed by MMS
The PADs display a characteristic donut‐like configuration
Betatron cooling and spatial dependence of electron pitch angle are able to produce such a distribution
Protected tomato cultivation is often subjected to low temperature stress in early spring season in north China. While low soil temperature returns slowly then low air temperature and causes damage ...to development of tomatoes, thereby reducing the growth of tomatoes, which seriously reduces the yield and quality of tomatoes. This study aimed to explore the effect of low root-zone temperature (LRT, i.e., 7 and 13℃) on the photosynthesis, root architecture, mineral use efficiency and aquaporins genes of tomato. Our findings indicated that LRT decreased the photosynthetic capacity accompanying with the reduction of CO2 assimilation. Meanwhile, a decrease in stomatal density and size occurred under low root-zone temperature. Stomatal conductance tended to reduce, which was unbeneficial to the diffusion of carbon dioxide and thus decreased photosynthesis. And there have the highest enzyme activity, and sucrose content compared to control. Root traits were remarkably affected by environment temperature. LRT delay root development processes and reduce the number and diameters of ducts in root and stem, thereby limiting mineral absorption and transport. Moreover, Under low root-zone temperature, the genes related to the aquaporin and element transport all showed varying degrees of response. Collectively, these results indicate that LRT may reduces the normal physiological activity of shoots by inhibiting the water transport, which inhibits the growth of tomato seedlings. Our research can provide detailed data to clarify the response characteristics of tomato to low root-zone temperature, and provide reference for low root-zone temperature response of tomato in practice.
This study investigated the effect of pH on cadmium toxicity to three aquatic organisms: Photobacterium phosphoreum, Daphnia magna and Carassius auratus. The acute toxicity of Cd2+ to P. phosphoreum ...and D. magna at five pH values (5.0, 6.0, 7.0, 8.0, and 9.0) was assessed by calculating EC50 values. We determined that Cd2+ was least toxic under acidic conditions, and D. magna was more sensitive to the toxicity of Cd than P. phosphoreum. To evaluate Cd2+-induced hepatic oxidative stress in C. auratus at three pH levels (5.0, 7.25, 9.0), the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase), the level of glutathione and the malondialdehyde content in the liver were measured. Oxidative damage was observed after 7d Cd exposure at pH 9.0. An important finding of the current research was that Cd2+ was generally more toxic to the three test organisms in alkaline environments than in acidic environments.
•The effect of pH on Cd toxicity to three aquatic organisms was investigated.•D. magna was more sensitive to the toxicity of Cd than P. phosphoreum.•Oxidative stress was induced in C. auratus in pH 9.0 water after 7d exposure.•Cd2+ was more toxic to three test organisms in alkaline environments.
This study investigated the effects of constant and cyclic heat stress on muscle metabolism and meat quality of broiler breast fillet and thigh meat from 4 to 6 wk of age. Male Arbor Acres (AA) ...broilers (n = 270, 4 wk old) were raised under different temperature conditions: standard (temperature was 23°C); constant high temperature (temperature was 34°C); and cyclic high temperature (temperature was 36°C from 1000 h to 1600 h and 23°C from 1600 h to 1000 h). On d 42, broilers were stunned and sampled. The results showed that chronic high temperature significantly decreased the proportion of breast muscle and significantly increased the proportion of thigh muscle (P < 0.05). The moisture concentration was significantly higher in the breast muscle of the birds exposed to constant high temperature (P < 0.05), whereas the protein content was significantly lower (P < 0.05) and fat deposition was significantly higher (P < 0.05) in the breast muscle of the birds exposed to constant or diurnal cyclic high temperature than those grown under standard temperature. The breast and thigh muscle of the birds grown under constant high temperature had significantly higher lightness, cook loss, and shear force (P < 0.05) and significantly lower initial pH (pH(i)), ultimate pH (pH(u)), and redness compared with those grown under standard temperature (P < 0.05). The pH(i), pH(u), and redness were significantly lower (P < 0.05) while the lightness and shear force were significantly higher for the breast muscle of the chickens raised under diurnal cyclic high temperature (P < 0.05) than those grown under standard temperature. In contrast, lightness and yellowness of thigh muscle were significantly higher (P < 0.05) in the chickens grown under diurnal cyclic high temperature than under standard temperature. Breast and thigh muscle of broilers exposed to constant high temperature produced higher (P < 0.05) lactic acid and pyruvate kinase activities than those exposed to the standard temperature. These results indicated that chronic heat stress significantly increased lactate production, reduced meat pH value by accelerating meat glycolysis, and eventually reduced meat quality.
The physical and chemical properties of cold and dense molecular clouds are key to understanding how stars form. Using the IRAM 30 m and NRO 45 m telescopes, we carried out a Multiwavelength ...line-Imaging survey of the 70 m-dArk and bright clOuds (MIAO). At a linear resolution of 0.1-0.5 pc, this work presents a detailed study of parsec-scale CO depletion and HCO+ deuterium (D-) fractionation toward four sources (G11.38+0.81, G15.22-0.43, G14.49-0.13, and G34.74-0.12) included in our full sample. In each source with T < 20 K and nH ∼ 104-105 cm−3, we compared pairs of neighboring 70 m bright and dark clumps and found that (1) the H2 column density and dust temperature of each source show strong spatial anticorrelation; (2) the spatial distribution of CO isotopologue lines and dense gas tracers, such as 1-0 lines of H13CO+ and DCO+, are anticorrelated; (3) the abundance ratio between C18O and DCO+ shows a strong correlation with the source temperature; (4) both the C18O depletion factor and D-fraction of HCO+ show a robust decrease from younger clumps to more evolved clumps by a factor of more than 3; and (5) preliminary chemical modeling indicates that chemical ages of our sources are ∼8 × 104 yr, which is comparable to their free-fall timescales and smaller than their contraction timescales, indicating that our sources are likely dynamically and chemically young.
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