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1.
A somatic protein from adult Haemonchus contortus (Hc23), the most abundant component in a low molecular weight fraction with known immunizing effect against experimental haemonchosis, has been purified by immunochromatography. The immunoprophylactic value of Hc23 was tested in groups of 5–6 months old Assaf lambs using Al(OH)3 or Escherichia coli lipopolysaccharide + inactivated Propionibacterium acnes as adjuvant and the results compared with uninfected control, uninfected and challenged or infected and challenged lambs. Immunization with Hc23 in either adjuvant elicited significant reductions in fecal egg counts after challenge with 15,000 L3s (70.67%–85.64%, respectively) and reduced (67.1% and 86%) abomasal worm counts (45 days post-challenge). Immunized lambs displayed higher peripheral eosinophil counts, were less anaemic and had weight gains than challenged controls. The results suggest that the Hc23 antigen can induce a partially protective response against haemonchosis in lambs.  相似文献   

2.
The head is kinematically constrained to the torso through the spine and thus, the spine dictates the amount of output head angular motion expected from an input impact. Here, we investigate the spinal kinematic constraint by analyzing the head instantaneous center of rotation (HICOR) with respect to the torso in head/neck sagittal extension and coronal lateral flexion during mild loads applied to 10 subjects. We found the mean HICOR location was near the C5-C6 intervertebral joint in sagittal extension, and T2-T3 intervertebral joint in coronal lateral flexion. Using the impulse-momentum relationship normalized by subject mass and neck length, we developed a non-dimensional analytical ratio between output angular velocity and input linear impulse as a function of HICOR location. The ratio was 0.65 and 0.50 in sagittal extension and coronal lateral flexion respectively, implying 30% greater angular velocities in sagittal extension given an equivalent impulse. Scaling to subject physiology also predicts larger required impulses given greater subject mass and neck length to achieve equivalent angular velocities, which was observed experimentally. Furthermore, the HICOR has greater motion in sagittal extension than coronal lateral flexion, suggesting the head and spine can be represented with a single inverted pendulum in coronal lateral flexion, but requires a more complex representation in sagittal extension. The upper cervical spine has substantial compliance in sagittal extension, and may be responsible for the complex motion and greater extension angular velocities. In analyzing the HICOR, we can gain intuition regarding the neck’s role in dictating head motion during external loading.  相似文献   

3.
For rigid body POSE estimation, any relative movement of the tracking markers on a segment is often referred to as an artefact; however this may be an important part of the signal within breast biomechanics. This study aimed to quantify differences in breast range of motion when calculated relative to the torso segment using either direct or segment optimised POSE estimation algorithms. Markers on the torso and right nipple were tracked using infrared cameras (200 Hz) during five running gait cycles in three breast support conditions (no bra, everyday bra and sports bra). Multiplanar breast range of motion was calculated relative to the torso segment using two POSE estimation algorithms. First, the torso segment was defined using direct POSE estimation (direct). Second, while standing stationary in the anatomical position; the positional data of the torso markers were used to construct the torso using segment optimised POSE estimation (optimised). The torso segment length defined using direct POSE estimation changed significantly by 3.4 cm compared to that of the segment optimisation POSE estimation in the no bra condition. Subsequently, superioinferior breast range of motion was significantly greater (p<0.017) when calculated using direct POSE estimation, within each of the three breast support conditions. Segment optimisation POSE estimation is recommended to minimise any differences in breast motion associated with intra segment deformation between physical activity types. However, either algorithm is recommended when evaluating different breast support garments, as a correctly fitted bra does not cause the torso markers to move relative to each other.  相似文献   

4.
The effect of carazolol on the ease of penetrating the cervix during artificial insemination, lambing rate and litter size was studied using 1.5–4.0-year old Kivircik ewes in an incomplete 3 × 2 × 2 experimental design. All of the ewes in this study were synchronized for oestrus by insertion of a progesterone impregnated vaginal sponge for 12 days and administration of 400 IU PMSG at sponge withdrawal. Three methods of service were compared: natural service, artificial insemination (AI) with fresh semen, or AI with frozen semen. Two times of insemination (fixed time AI versus AI at observed oestrus) were compared on the fresh and frozen AI treatments. The absence (control) or use of carazolol (carazolol; 0.5 mg/ewe i.m. 30 min before mating) was the third factor in the design and penetration of the cervix by the insemination pipette was assessed as shallow (<10 mm), middle (10–20 mm) or deep (>20 mm). Natural service ewes were only mated at observed oestrus. Consequently, the factorial design was incomplete and there were a total of 10 treatments each represented by 30 ewes. Natural service resulted in a significantly (P < 0.05) higher lambing rate and litter size (86%; 2.0 ± 0.05 lambs/ewe) than AI using fresh (65%; 1.6 ± 0.1 lambs/ewe) or frozen (40%; 1.4 ± 0.14 lambs/ewe) semen. For AI animals the lambing rate and litter size were not significantly different when service was at a fixed time (50%; 1.5 ± 0.12 lambs/ewe) or at observed oestrus (56%; 1.5 ± 0.12 lambs/ewe). Carazolol did not permit complete cervical penetration in any ewe. Deep penetration of the cervix at AI was achieved in 33% of untreated (control) and 48% of carazolol treated ewes (P < 0.05). However, the proportion of ewes in which penetration of the cervix and semen deposition was greater than shallow was similar for control (82%) and carazolol (85%), and lambing rate and litter size were similar for both treatments. Over the three service methods, the lambing rate was 56% for control and 63% for carazolol (NS) and litter size was similar for both treatments. It was concluded that the carazolol treatment used prior to natural mating or AI in this experiment did not improve lambing rate or litter size in Kivircik ewes.  相似文献   

5.
The aerodynamic drag of a cyclist in time trial (TT) position is strongly influenced by the torso angle. While decreasing the torso angle reduces the drag, it limits the physiological functioning of the cyclist. Therefore the aims of this study were to predict the optimal TT cycling position as function of the cycling speed and to determine at which speed the aerodynamic power losses start to dominate. Two models were developed to determine the optimal torso angle: a ‘Metabolic Energy Model’ and a ‘Power Output Model’. The Metabolic Energy Model minimised the required cycling energy expenditure, while the Power Output Model maximised the cyclists? power output. The input parameters were experimentally collected from 19 TT cyclists at different torso angle positions (0–24°). The results showed that for both models, the optimal torso angle depends strongly on the cycling speed, with decreasing torso angles at increasing speeds. The aerodynamic losses outweigh the power losses at cycling speeds above 46 km/h. However, a fully horizontal torso is not optimal. For speeds below 30 km/h, it is beneficial to ride in a more upright TT position. The two model outputs were not completely similar, due to the different model approaches. The Metabolic Energy Model could be applied for endurance events, while the Power Output Model is more suitable in sprinting or in variable conditions (wind, undulating course, etc.). It is suggested that despite some limitations, the models give valuable information about improving the cycling performance by optimising the TT cycling position.  相似文献   

6.
Studies on Caulerpa prolifera rhizoids were carried out to determine the possibility of mass culture, because the rhizoids produce a bio-adhesive. Rhizoids can be induced by cutting the base of a blade and floating it in a media or planting it in sand. Measurement of rhizoid production included determination of number, length, and the weight of attached sand grains. The growth experiments were for 1–2 weeks and fronds growth was compared to rhizoid production. Optimal conditions for rhizoid growth included low levels of nitrogen and phosphate (less than 5 and 2 μM, respectively), low irradiance (30 μmol photon m−2 s−1), moderate temperature (22–28°), continuous shaking, addition of microelements and auxin (1 ppm) and initially detached fronds followed by attachment. Under these optimal conditions maximal weekly growth reached 70–170 rhizoids per blade, 7–11 mm length and maximal attachment to sand grains. Blade growth of C. prolifera responded similarly to rhizoid production and reached a weekly growth rate of 30–130%.  相似文献   

7.
BackgroundForward head posture is a head-on-trunk malalignment, which results in musculoskeletal dysfunction and neck pain. To improve forward head posture, both the craniocervical flexion exercise and the suboccipital release technique have been used. Objectives: The purpose of this study was to compare the immediate effects of craniocervical flexion exercise and suboccipital release combined with craniocervical flexion exercise on craniovertebral angle, cervical flexion and extension range of motion, and the muscle activities of the sternocleidomastoid, anterior scalene, and splenius capitis during craniocervical flexion exercise in subjects with forward head posture.MethodsIn total, 19 subjects (7 males, 12 females) with forward head posture were recruited using G-power software. Each subject performed craniocervical flexion exercise and suboccipital release combined with craniocervical flexion exercise in random order. After one intervention was performed, the subject took a 20 min wash out period to minimize any carry-over effect between interventions. Craniovertebral angle, cervical flexion and extension range of motion, and the muscle activities of the sternocleidomastoid, anterior scalene, and splenius capitis were measured. A one-way, repeated-measures ANOVA was used to assess differences between the effects of the craniocervical flexion exercise and suboccipital release combined with craniocervical flexion exercise interventions in the same group.ResultsCraniovertebral angle (p < 0.05), cervical flexion range of motion (p < 0.05), and cervical extension range of motion (p < 0.001) were significantly greater after suboccipital release combined with craniocervical flexion exercise compared to craniocervical flexion exercise alone. The muscle activities of the sternocleidomastoid, anterior scalene, and splenius capitis were significantly lower during suboccipital release combined with craniocervical flexion exercise than during craniocervical flexion exercise alone across all craniocervical flexion exercise phases except the first (all p < 0.05).ConclusionThe addition of suboccipital release to craniocervical flexion exercise provided superior benefits relative to craniocervical flexion exercise alone as an intervention for subjects with forward head posture.  相似文献   

8.
The adsorption behavior of drin pesticides from aqueous solution onto acid treated olive stones (ATOS) was investigated using stir bar sorptive extraction and gas chromatography coupled with mass spectroscopy. The effects of sorbent particle size, adsorbent dose, contact time, concentration of pesticide solution and temperature on the adsorption processes were systematically studied in batch shaking sorption experiments. Maximum removal efficiency (94.8%) was reached for aldrin (0.5 mg L−1) using the fraction 63–100 μm of ATOS (solid/liquid ratio: 1 g L−1). Experimental data were modeled by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherms. The Freundlich isotherm model (R2 = 0.98–0.99) fitted the equilibrium data better than the Langmuir and D–R isotherm models, with low sum of error values (SE = 1.4–9.2%). The mean adsorption free energy derived from the D–R isotherm model (R2 = 0.95–0.99) showed that the adsorption of drin pesticides was taken place by weak physical forces, such as van der Waals forces and hydrogen bonding. The calculated thermodynamic parameters, ΔH, ΔS and ΔG prove that drin pesticides adsorption on ATOS was feasible, spontaneous and exothermic under examined conditions. The pseudo first order, pseudo second order kinetic and the intra-particle diffusion models were used to describe the kinetic data and rate constants were evaluated.  相似文献   

9.
Using the method of Orne and Liu (1971) a discrete-parameter model of the head, neck and torso has been developed to allow investigation of the ‘whiplash’ problem. Following a 5g acceleration pulse applied to the seat base it was found that some degree of initial flexion of the head relative to the torso occurred prior to rapid hyperextension. The degree of initial flexion was found to increase with decreasing seatback stiffness. Head, horizontal and rotational acceleration profiles revealed that the peak values reached displayed a similar relationship to seatback stiffness. An examination of the loading distribution in the cervical spine showed that maximums were reached during the hyperextension phase and were of greatest magnitude in the low cervical region. These forces were larger and consequently more damaging for seatbacks of decreasing stiffness characteristics.  相似文献   

10.
Joint moments help us understand joint loading and muscle function during movement. However, the interpretation depends on the choice of reference frame, but the different reference frames have not been compared in dynamic, high-impact sporting movements. We have compared the magnitude and the resulting ranking of hip and knee joint moments expressed in the laboratory coordinate system, the local system of the distal segment and projected or decomposed to the Joint Coordinate System (JCS) axes. Hip and knee joint moments of drop jumps and sidestep cutting in 70 elite female handball players were calculated based on recordings from an eight-camera 240 Hz system and two force platforms and expressed with the four methods. The greatest variations in magnitude between conditions were seen for drop jump hip internal rotation (range: 0.31–0.71 Nm/kg) and sidestep cutting knee flexion (2.87–3.39 Nm/kg) and hip internal rotation (0.87–2.36 Nm/kg) and knee internal rotation (0.10–0.40 Nm/kg) moments. The rank correlations were highest between conditions for flexion moments (0.88–1.00) and sidestep cutting abduction moments (0.71–0.98). The rank correlations ranged from 0.64 to 0.73 for drop jump knee abduction moments and between −0.17 and 0.67 for hip and knee internal rotation moments. Expression of joint moments in different reference systems affects the magnitude and ranking of athletes. This lack of consistency may complicate the comparison and combination of results. Projection to the JCS is the only method where joint moments correspond to muscle and ligament loading. More widespread adoption of this convention could facilitate comparison of studies and ease the interpretation of results.  相似文献   

11.
An increased knee abduction angle during jump-landing has been identified as a risk factor for anterior cruciate ligament injuries. Activation of the hip abductors may decrease the knee abduction angle during jump-landing. The purpose of this study was to examine the effects of a resistance band on the internal hip abduction moment and gluteus medius activation during the pre-landing (100 ms before initial contact) and early-landing (100 ms after initial contact) phases of a jump–landing–jump task. Thirteen male and 15 female recreational athletes (age: 21.1±2.4 yr; mass: 73.8±14.6 kg; height: 1.76±0.1 m) participated in the study. Subjects performed jump–landing–jump tasks with or without a resistance band applied to their lower shanks. During the with-band condition, subjects were instructed to maintain their movement patterns as performing the jump-landing task without a resistance band. Lower extremity kinematics, kinetics, and gluteus medius electromyography (EMG) were collected. Applying the band increased the average hip abduction moment during pre-landing (p<0.001, Cohen?s d (d)=2.8) and early-landing (p<0.001, d=1.5), and the average gluteus medius EMG during pre-landing (p<0.001, d=1.0) and early-landing (p=0.003, d=0.55). Applying the band decreased the initial hip flexion angle (p=0.028, d=0.25), initial hip abduction angle (p<0.001, d=0.91), maximum knee flexion angle (p=0.046, d=0.17), and jump height (p=0.004, d=0.16). Applying a resistance band provides a potential strategy to train the strength and muscle activation for the gluteus medius during jump-landing. Additional instructions and feedback regarding hip abduction, hip flexion, and knee flexion may be required to minimize negative changes to other kinematic variables.  相似文献   

12.
The enzyme-linked immunosorbent assay (ELISA) constitutes an important clinical diagnostic approach. However, the prolonged incubation times involved lead to turnaround times of typically ?1 day, potentially delaying a definitive diagnosis or an adequate treatment plan for individual patients. Here cold-microwave technology (CMT) was employed to significantly reduce the times required for diagnostic ELISAs. The new approach was validated and compared to a conventional ELISA setup measuring canine calprotectin (cCP). Canine serum and fecal specimens were used for the analytical validation of cCP ELISA by conventional and CMT–ELISA. Cross-validation of both ELISA methods consisted of the determination of analytic sensitivity, linearity, accuracy, precision, and reproducibility. The long-term stability of antibody-coated ELISA plates was also evaluated up to 33 days. The ELISA approaches were comparable to each other. The observed-to-expected ratios for linearity and accuracy were 100.2 ± 11.8 and 98.1 ± 10.8% (mean ± standard deviation), respectively. Precision and reproducibility were ?17.2%. For samples run on precoated ELISA plates over 33 days %CVs were ?12.5%. While both ELISA approaches were analytically sensitive, linear, accurate, precise, and reproducible with measurements of cCP concentrations, CMT–ELISA offered a reduction in incubation times by 90–95%, facilitating a very fast turnaround time and suggesting CMT–ELISA for improved human and veterinary clinical diagnostics.  相似文献   

13.

Background

Gene polymorphisms of the chemokine receptors CCR2 and CCR5 (CCR2V64I, CCR5-59029G>A and CCR5Δ32) have been shown to be associated with renal allograft rejection. The aim of this study was to investigate the association of these polymorphisms with allograft rejection among Pakistani transplant patients.

Method

A total of 606 renal transplant patients and an equal number of their donors were included in this study. DNA samples were used to amplify polymorphic regions of CCR2V64I, CCR5-59029G>A and CCR5Δ32 by polymerase chain reaction using sequence specific primers. The amplified products of CCRV64I and CCR5-59029G>A were digested with restriction enzymes (BsaB1 and Bsp12861) respectively. The CCR5Δ32 genotypes were determined by sizing the PCR amplicons. The association of these polymorphisms with the biopsy proven rejection and other clinical parameters was evaluated using the statistical software SPSS v.17.

Results

In this study, the G/G genotype of CCR2V64I was associated with a high frequency of allograft rejection (p = 0.009; OR = 2.14; 95% CI = 1.2–3.7). Rejection episode(s) in the GA + AA genotypes were found to be significantly lower as compared to the GG genotype (p = 0.009; OR = 0.4; 95% CI = 0.2–0.8). The Kaplan–Meier curve also indicated a reduced overall allograft survival for patients with the G/G genotype of CCR2V64I (59.2 ± 1.4 weeks, log p = 0.008). There was a significant association with rejection by female donors possessing the CCR2 GG genotype (p = 0.02; OR = 2.6; CI = 1.1–6.3) and male donors with the CCR5-59029 GG genotype (p = 0.004; OR = 1.7; CI = 1.03–3.01).

Conclusion

This study shows an association of the CCR2V64I (G/G) genotype with renal allograft rejection. However, no such association was found for the CCR5 gene polymorphisms. Therapeutic interventions such as blocking the CCR2 receptor (especially G polymorphism) may yield better survival of renal allograft in this patient group. Further, chemokine receptors may be added to the spectrum of the immunogenetic factors that are known to be associated with renal allograft rejection.  相似文献   

14.
Experimental studies have found significant variation in cervical intervertebral kinematics (IVK) among healthy subjects, but the effect of this variation on biomechanical properties, such as neck strength, has not been explored. The goal of this study was to quantify variation in model predictions of extension strength, flexion strength and gravitational demand (the ratio of gravitational load from the weight of the head to neck muscle extension strength), due to inter-subject variation in IVK. IVK were measured from sagittal radiographs of 24 subjects (14F, 10M) in five postures: maximal extension, mid-extension, neutral, mid-flexion, and maximal flexion. IVK were defined by the position (anterior-posterior and superior-inferior) of each cervical vertebra with respect to T1 and its angle with respect to horizontal, and fit with a cubic polynomial over the range of motion. The IVK of each subject were scaled and incorporated into musculoskeletal models to create models that were identical in muscle force- and moment-generating properties but had subject-specific kinematics. The effect of inter-subject variation in IVK was quantified using the coefficient of variation (COV), the ratio of the standard deviation to the mean. COV of extension strength ranged from 8% to 15% over the range of motion, but COV of flexion strength was 20–80%. Moreover, the COV of gravitational demand was 80–90%, because the gravitational demand is affected by head position as well as neck strength. These results indicate that including inter-individual variation in models is important for evaluating neck musculoskeletal biomechanical properties.  相似文献   

15.
T3801C is a common polymorphism in CYP1A1, showing differences in its biological functions. Case–control studies have been performed to elucidate the role of T3801C in cancer, although the results are conflicting and heterogeneous. Hence, we performed a meta-analysis to investigate the association between cancer susceptibility and T3801C (55,963 cases and 76,631 controls from 268 studies) polymorphism in different inheritance models. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, significantly increased cancer risk was observed in any genetic model (dominant model: odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.09–1.19; recessive model: OR = 1.23, 95% CI = 1.12–1.34; CC vs. TT: OR = 1.31, 95% CI = 1.19–1.45; TC vs. TT: OR = 1.12, 95% CI = 1.07–1.18; additive model: OR = 1.14, 95% CI = 1.09–1.19) when all eligible studies were pooled into the meta-analysis. In further stratified and sensitivity analyses, the elevated risk remained for subgroups of cervical cancer, head and neck cancer, hepatocellular cancer, leukemia, lung cancer, prostate cancer and breast cancer. In addition, significantly decreased colorectal cancer risk was also observed. In summary, this meta-analysis suggests that the participation of CYP1A1 T3801C is a genetic susceptibility for some cancer types. Moreover, our work also points out the importance of new studies for T3801C association in some cancer types, such as gallbladder cancer, Asians of acute myeloid leukemia, and thyroid cancer, where at least some of the covariates responsible for heterogeneity could be controlled, to obtain a more conclusive understanding about the function of the CYP1A1 T3801C polymorphism in cancer development.  相似文献   

16.

Aims

Epidemiological studies have assessed the association between xeroderma pigmentosum group D (XPD) Lys751Gln and acute leukemia risk with conflicting results. We performed this meta-analysis to derive a more precise estimation of the relationship. Pooled odds ratio (OR) with 95% confidence interval (95% CI) was used to assess the strength of the association.

Results

Ten published case–control studies including a total of 1494 cases and 2259 controls were identified. Overall, significant risk effects of Lys751Gln genotype was found under the dominant model (OR = 1.16; 95% CI = 1.01–1.34; P = 0.032). When stratified by clinical types, the variant genotype was associated with the acute myeloid leukemia (AML) risk under the heterozygote comparison (OR = 1.20; 95% CI = 1.00–1.43; P = 0.048), the homozygote comparison (OR = 1.35; 95% CI = 1.05–1.74; P = 0.019) and the dominant model (OR = 1.23; 95% CI = 1.04–1.45; P = 0.015), respectively. Furthermore, significantly increased risks were also pronounced in Caucasian AML patients (the homozygote comparison: OR = 1.38; 95% CI = 1.07–1.78; P = 0.013; the dominant model: OR = 1.23; 95% CI = 1.03–1.46; P = 0.020; and the recessive model: OR = 1.26; 95% CI = 1.00–1.60; P = 0.050). No evident heterogeneities were observed for the overall data under all genetic models. In addition, no statistical evidence for publication bias was found using the method of Begg's and Egger's tests.

Conclusion

This meta-analysis suggested that XPD Lys751Gln polymorphism might be a risk factor for AML and Caucasian acute leukemia patients.  相似文献   

17.
18.
The aim of this study was first to search for isofolliculia in right and left ovaries during postnatal development of Ouled Djellel ewe lambs, a non-seasonal breed of sheep. In addition, the contribution of different sizes of large antral follicles to this phenomenon was studied, and finally the variations in both plasma FSH and LH levels during this period of life were determined. Plasma was collected from groups of four ewe lambs at 0 (<24 h), 1 week, and every 2 weeks from 4 to 14 weeks of age. Thereafter, each group was slaughtered, right and left ovaries recovered, weighed and their length and width measured. One ovary was fixed in Bouin–Holland's solution and prepared for histological study. The other one was immediately frozen and cut in a cryostat and prepared for histochemical study. This latter method was used to detect the activity of alkaline phosphatase, lactate dehydrogenase, NADH2-tetrasolium reductase, and glucose-6-phosphate dehydrogenase enzymes. Number and size of antral follicles and their contribution to isofolliculia were determined from ovarian sections of both studies. Isofolliculia was seen in right and left ovaries of Ouled Djellel ewe lambs at 4, 6, 8, and 10 weeks of age. This phenomenon was characterized by the presence of large antral follicles almost equal in size and total enzymatic inactivity in the interstitium. Weight and dimensions of right and left ovaries increased rapidly from birth to 4 weeks of age, and then rose gradually to week 8 and then rising again to week 10, followed by a decline at 12 and 14 weeks of age. All large antral follicles contributed to isofolliculia in right and left ovaries but, the percentage of antral follicles <2 mm at 4, 6, 8, and 10 weeks of age were significantly greater than the percentage of follicles ≥2 and <3 mm and the contribution of follicles ≥3 mm was the lowest. FSH levels increased slowly from birth to 6 weeks of age then, increased rapidly to week 10, followed by a decline at weeks 12 and 14. LH was low at birth and the level increased slowly to 8 weeks of age, followed by a further rapid increase at 10 weeks of age. All parameters studied did not show any significant differences between the right and left ovary. It was concluded that isofolliculia occurred between 4 and 10 weeks of age in left and right ovaries of Ouled Djellel ewe lambs. This phenomenon was characterized by the increase of both ovarian weights and dimensions, and of plasma FSH and LH levels. All large antral follicles ≥1 mm in diameter contributed to isofolliculia but the contribution of antral follicles <2 mm was greater than the contribution of antral follicles ≥2.  相似文献   

19.
This work describes the potential applicability of chemically and thermally treated date stones for removing drin pesticides (aldrin, dieldrin and endrin) from aqueous solutions. The effect of several parameters, such as sorbent particle size, adsorbent dose, shaking speed, shaking time, concentration of pesticide solution and temperature, was evaluated by batch experiments. Pesticide determination was carried out using stir bar sorptive extraction and gas chromatography coupled with mass spectroscopy. Maximum removal efficiency (93%) was reached using 0.1 g of acid-treated date stones (ATDS) (63–100 μm) and 100 mL of aldrin (0.5 mg L−1). The removal efficiency of drin pesticides decreased in the order of aldrin, dieldrin and endrin, and decreased as the temperature rose. Adsorption data were processed according to various kinetic models. Lagergren and Morris-Weber equations were applied to fit the kinetic results. The second order model was the most suitable on the whole, and intra-particle diffusion was found to be the rate-controlling the adsorption process. According to adsorption kinetic data, 3.5 h were considered as the equilibrium time for determining adsorption isotherms. Adsorption data were analyzed by the Langmuir, Freundlich and Dubinin–Radushkevich adsorption approaches. Experimental results showed that the Freundlich isotherm model best described the adsorption process. In addition, thermodynamic parameters such as ΔH, ΔS and ΔG were calculated. Negative values of ΔH and ΔG indicate the exothermic and spontaneous nature of pesticide adsorption on ATDS.  相似文献   

20.
A repeatable method for in vivo and in vitro measurement of polyethylene wear in total knee replacement (TKA) is needed. This research examines the model-based radiostereometric analysis’ (MBRSA) in vitro precision under different patient-radiograph orientations and flexion angles of the knee using a TKA phantom. Anterior–posterior and medial–lateral imaging orientations showed the highest precision; better than 0.036 mm (3-dimensional translation) and 0.089° (3-dimensional rotation). Flexion of the knee did not affect MBRSA precision. Medial–lateral imaging is advantageous as it allows for flexion of the knee joint during an RSA examination, thus providing greater information for wear measurement.  相似文献   

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