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1.
Appl Ergon ; 98: 103555, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34425517

RESUMO

PURPOSE: Although firefighters are required to perform various high-intensity critically essential tasks, the influence of neuromuscular function on firefighter occupational performance is unclear. The primary aim of the current study was to identify the key neuromuscular determinants of stair climb (SC) performance in firefighters. METHODS: Leg extension isometric peak torque (PT), peak power (PP), torque steadiness at 10% (Steadiness10%) and 50% (Steadiness50%) of PT, fatigability following 30 repeated isotonic concentric contractions at 40% of PT, percent body fat (%BF), and a weighted and timed SC task were examined in 41 (age: 32.3 ± 8.2 yrs; %BF: 24.1 ± 7.9%) male career firefighters. RESULTS: Faster SC times (74.7 ± 13.4 s) were associated with greater PT and PP, less fatigability, younger age, and lower %BF (r = -0.530-0.629; P ≤ 0.014), but not Steadiness10% or Steadiness50% (P ≥ 0.193). Stepwise regression analyses indicated that PP and Steadiness50% were the strongest predictors of SC time (R2 = 0.442, P < 0.001). However, when age and %BF were included in the model, these variables became the only significant predictors of SC time (R2 = 0.521, P < 0.001) due to age and %BF being collectively associated with all the neuromuscular variables (excluding Steadiness10%). CONCLUSIONS: Lower extremity neuromuscular function, specifically PP and steadiness, and %BF are important modifiable predictors of firefighter SC performance, which becomes increasingly important in aging firefighters.


Assuntos
Bombeiros , Adulto , Envelhecimento , Humanos , Extremidade Inferior , Masculino , Força Muscular , Torque , Adulto Jovem
2.
J Indian Prosthodont Soc ; 21(4): 366-374, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34810364

RESUMO

Aim: Successful functional and esthetic rehabilitation of edentulous jaws with implants depends on the optimal timing of placement, surgical protocol, materials used, cost-effectiveness, and satisfying patient needs. Increasing demand for shorter treatment times necessitates the immediate placement protocol. However, researchers have demonstrateda higher failure rate. A-PRF (Advanced platelet-rich fibrin) has exhibited accelerated bone regeneration potential. Early implant placement with a limited healing period, along with A-PRF, can be beneficial over conventional and immediate implant placement. Settings and Design: This prospective randomized clinical trial aims to assess the outcome of early implant placement in sockets preserved using A-PRF at six weeks and eight weeks of post-extraction. Two groups of 10 participantseach were formed. All patients underwent atraumatic extraction and socket preservation using A-PRF. Materials and Methods: A Partial-thickness pedicle graft was raised, and the extraction socket wasclosed. Implants wereplaced in at six and eight weeks of post-extraction in group A group B, respectively. The histomorphometric analysisassessedthe bone quality present at the timeof surgery. The insertion torque values were recorded during implant placement. Statistical Analysis Used: The obtained data were statistically analyzed using parametric tests, namely independent T-test for intergroup comparison. Results: T-test for torque values indicated a significantly higher torque value at eight weeks. The meanhistomorphometric value showeda significantly higher percentage of bone formation at eight weeks than at six weeks (P = 0.03). Conclusion: Within the study's limitations, early implant placement in extraction sockets preserved with A-PRF had significantly higher insertion torque values and predictable bone at eight weeks compared to six weeks.


Assuntos
Fibrina Rica em Plaquetas , Implantes Absorvíveis , Humanos , Estudos Prospectivos , Extração Dentária , Alvéolo Dental/cirurgia , Torque , Resultado do Tratamento
3.
Artigo em Inglês | MEDLINE | ID: mdl-34770202

RESUMO

BACKGROUND: The present study analyzes the associations between the muscle contractile properties (MCP) measured at different neuromuscular electrical stimulation amplitudes (NMESa) and the performance or transient fatigue after a bout of repeated sprints. METHODS: Seventeen physically active male subjects performed six repeated sprints of 30 m with 30 s of passive recovery. Capillary blood creatine kinase (CK) concentration, knee extension or flexion isometric peak torque, tensiomyography, and repeated sprint performance were assessed. RESULTS: Muscle displacement and contraction time were different in relation to the NMESa used in the rectus femoris and biceps femoris muscles. At rest, significant (p < 0.05) associations were found between muscle displacement and the loss of time in the repeated sprints (sprint performance) at 20 or 40 mA in the rectus femoris. At post +24 h or +48 h, the highest significant associations were found between the muscle displacement or the contraction time and CK or peak torques also at submaximal amplitudes (20 mA). The NMESa which elicits the peak muscle displacement showed lack of practical significance. CONCLUSION: Although MCP are typically assessed in tensiomyography using the NMESa that elicit peak muscle displacement, a submaximal NMESa may have a higher potential practical application to assess neuromuscular fatigue in response to repeated sprints.


Assuntos
Fadiga Muscular , Músculo Esquelético , Eletromiografia , Humanos , Joelho , Masculino , Contração Muscular , Torque
4.
Am J Orthod Dentofacial Orthop ; 160(5): 641-642, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34752248

Assuntos
Movimento , Humanos , Torque
5.
Prog Orthod ; 22(1): 42, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34778924

RESUMO

BACKGROUND: The current study aimed to evaluate factors affecting the long-term stability of microimplants using removal torque and the correlation between removal torque and clinical variables. MATERIALS AND METHODS: This research evaluated 703 microimplants placed in 354 patients (mean age: 30.4 ± 12.1 years). The removal torque was evaluated according to various clinical variables including sex, age, placement site, microimplant size, and placement method (self-drilling versus pre-drilling). Pearson correlation and stepwise multiple linear regression analyses were performed to investigate different variables and their association with removal torque. RESULTS: The mean removal torque was significantly higher in the mandible (4.46 N cm) than in the maxilla (3.73 N cm). The values in the posterior teeth/retromolar areas were significantly higher than those in the anterior teeth area. There were no significant difference in terms of sex. Teenagers had a lower removal torque than older adults in the mandible, but not in the maxilla. Microimplants with a greater length and diameter, except for those with a greater diameter in the maxilla, was associated with a higher removal torque. Regardless of placement torque, the removal torque convergently reached approximately 4 N cm in both placement methods. The removal torque was significantly correlated with screw length in the self-drilling group and with diameter in the pre-drilling group. CONCLUSIONS: Removal torque was related with placement site, age, placement method, and length and diameter of microimplants.


Assuntos
Implantes Dentários , Procedimentos de Ancoragem Ortodôntica , Adolescente , Adulto , Idoso , Humanos , Mandíbula/cirurgia , Maxila/cirurgia , Torque , Adulto Jovem
6.
Sensors (Basel) ; 21(19)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34640867

RESUMO

With the emerging of wearable robots, the safety and effectiveness of human-robot physical interaction have attracted extensive attention. Recent studies suggest that online measurement of the interaction force between the robot and the human body is essential to the aspects above in wearable exoskeletons. However, a large proportion of existing wearable exoskeletons monitor and sense the delivered force and torque through an indirect-measure method, in which the torque is estimated by the motor current. Direct force/torque measuring through low-cost and compact wearable sensors remains an open problem. This paper presents a compact soft sensor system for wearable gait assistance exoskeletons. The contact force is converted into a voltage signal by measuring the air pressure within a soft pneumatic chamber. The developed soft force sensor system was implemented on a robotic hip exoskeleton, and the real-time interaction force between the human thigh and the exoskeleton was measured through two differential soft chambers. The delivered torque of the hip exoskeleton was calculated based on a characterization model. Experimental results suggested that the sensor system achieved direct force measurement with an error of 10.3 ± 6.58%, and torque monitoring for a hip exoskeleton which provided an understanding for the importance of direct force/torque measurement for assistive performance. Compared with traditional rigid force sensors, the proposed system has several merits, as it is compact, low-cost, and has good adaptability to the human body due to the soft structure.


Assuntos
Exoesqueleto Energizado , Procedimentos Cirúrgicos Robóticos , Marcha , Humanos , Monitorização Fisiológica , Torque
7.
Sensors (Basel) ; 21(19)2021 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-34640917

RESUMO

Joint torques of lower extremity are important clinical indicators of gait capability. This parameter can be quantified via hybrid neuromusculoskeletal modelling that combines electromyography-driven modelling and static optimisation. The simulations rely on kinematics and external force measurements, for example, ground reaction forces (GRF) and the corresponding centres of pressure (COP), which are conventionally acquired using force plates. This bulky equipment, however, hinders gait analysis in real-world environments. While this portability issue could potentially be solved by estimating the parameters through machine learning, the effect of the estimation errors on joint torque prediction with biomechanical models remains to be investigated. This study first estimated GRF and COP through feedforward artificial neural networks, and then leveraged them to predict lower-limb sagittal joint torques via (i) inverse dynamics and (ii) hybrid modelling. The approach was evaluated on five healthy subjects, individually. The predicted torques were validated with the measured torques, showing that hip was the most sensitive whereas ankle was the most resistive to the GRF/COP estimates for both models, with average metrics values being 0.70 < R2 < 0.97 and 0.069 < RMSE < 0.15 (Nm/kg). This study demonstrated the feasibility of torque prediction based on personalised (neuro)musculoskeletal modelling using statistical ground reaction estimates, thus providing insights into potential real-world mobile joint torque quantification.


Assuntos
Análise da Marcha , Marcha , Articulação do Tornozelo , Fenômenos Biomecânicos , Humanos , Torque
8.
Artigo em Inglês | MEDLINE | ID: mdl-34682378

RESUMO

The different effects of intermittent and continuous stretching on the mechanical properties of the musculotendinous complex have been unclear. This study aimed to compare the effects of intermittent and continuous stretching for the same duration on the range of motion (ROM), passive resistive torque (PRT), and musculotendinous stiffness (MTS) of ankle plantar flexors. Eighteen healthy young men participated in the study. Intermittent (four sets × 30 s) and continuous stretching (one set × 120 s) were performed in random orders on two separate days. Both stretching protocols were conducted using a dynamometer with a constant torque applied. ROM and PRT were determined using a dynamometer, and MTS was calculated using the torque-angle relationship measured before and after stretching. Two-way repeated measures analysis of variance was performed for all parameters. Both intermittent and continuous stretching significantly increased ROM and decreased PRT and MTS (p < 0.05). Intermittent stretching led to greater changes in ROM and PRT than continuous stretching. However, the reduction in MTS did not differ between the two conditions. These results suggest that intermittent stretching is more effective in increasing ROM and changing the mechanical properties of the musculotendinous complex.


Assuntos
Exercícios de Alongamento Muscular , Humanos , Masculino , Músculo Esquelético , Amplitude de Movimento Articular , Tendões , Torque
9.
Int J Implant Dent ; 7(1): 98, 2021 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-34604929

RESUMO

PURPOSE: The aim of this study was to compare removal torque values after mechanical cyclic loading and bending moment after the static compression testing of customized titanium abutment compared with prefabricated and hybrid abutments. MATERIALS AND METHODS: The study was developed according to ISO 14801:2016. Sixty implants were divided into three groups equally: Straight titanium abutment group, Customized titanium abutment group, and Hybrid zirconia abutment group. Abutments were fabricated with zirconia restoration. Forty five implants underwent for cyclic loading. The removal torque values were measured after a fatigue test was conducted at 0 cycles (control), 50,000 cycles and 1,000,000 cycles. In the second experiment, 15 implants were divided into the same groups. Then, bending moments were investigated. RESULTS: The mean initial removal torque value was significantly higher than 50,000 cycles and 1,000,000 cycles (P < 0.001). The comparison of mean removal torque value between types of abutments was not significantly different (P > 0.05), and the bending moments of all abutments were not significantly different (P > 0.05). CONCLUSIONS: From the boundary of this in-vitro study, it could be concluded that customized titanium abutment and hybrid abutment were not significantly different in terms of removal torque values after the fatigue test. The bending moment between types of abutment were not significantly different. Thus, it could be concluded that abutment type does not significantly influence abutment stability or fracture strength.


Assuntos
Parafusos Ósseos , Titânio , Teste de Materiais , Torque , Zircônio
10.
PLoS One ; 16(10): e0257985, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34618848

RESUMO

OBJECTIVES: The aims of this study were to compare the initial implant stability obtained using four different osteotomy techniques in low-density synthetic bone, to evaluate the instrument design in comparison to the implant design, and to determinate a possible correlation between the insertion torque and initial stability quotient (ISQ). MATERIALS AND METHODS: Four groups were identified in accordance with the osteotomy technique used (n = 10 implants per group): group G1, osteotomy using the recommended drilling sequence; group G2, osteotomy using an undersized compactor drill; group G3, osteotomy using an undersized drill; and group G4, osteotomy using universal osseodensification drills. Two polyurethane blocks were used: block 1, with a medullary portion of 10 pounds per cubic foot (PCF 10) and with a 1 mm cortical portion of PCF 40, and block 2, with a medullary of PCF 15 and with a 2 mm cortical portion of PCF 40. Tapered implants of 4 mm in diameter and 11 mm in length were used. The insertion torque (IT) and ISQ were measured. The dimensions of the final instrument used in each group and the dimensions of the implant were used to calculate the total area of each part, and these data were compared. RESULTS: Differences between the four groups were found for IT and ISQ values depending on the technique used for the osteotomy in the two synthetic bone models (p < 0.0001). All groups showed lower values of initial stability in block 1 than in block 2. CONCLUSIONS: Undersized osteotomies with instruments designed according to the implant body significantly increased the initial stability values compared to beds prepared with universal drills and using the drilling sequence standardized by the manufacturer.


Assuntos
Osso e Ossos/cirurgia , Implantação Dentária Endo-Óssea/instrumentação , Osteotomia/instrumentação , Próteses e Implantes , Densidade Óssea , Doenças Ósseas Metabólicas , Osso e Ossos/fisiopatologia , Brasil , Humanos , Projetos Piloto , Poliuretanos/química , Poliuretanos/uso terapêutico , Torque
11.
Nutrients ; 13(10)2021 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-34684368

RESUMO

The present study uniquely examined the effect of 3 mg·kg-1 chronic caffeine consumption on training adaptations induced by 7-weeks resistance training and assessed the potential for habituation to caffeine's ergogenicity. Thirty non-specifically resistance-trained university standard male rugby union players (age (years): 20 ± 2; height (cm): 181 ± 7; body mass (kg): 92 ± 17) completed the study), who were moderate habitual caffeine consumers (118 ± 110 mg), completed the study. Using a within-subject double-blind, placebo-controlled experimental design, the acute effects of caffeine intake on upper and lower limb maximal voluntary concentric and eccentric torque were measured using isokinetic dynamometry (IKD) prior to and immediately following a resistance training intervention. Participants were split into strength-matched groups and completed a resistance-training program for seven weeks, consuming either caffeine or a placebo before each session. Irrespective of group, acute caffeine consumption improved peak eccentric torque of the elbow extensors (p < 0.013), peak concentric torque of the elbow flexors (p < 0.005), total eccentric work of the elbow flexors (p < 0.003), total concentric work of the knee extensors (p < 0.001), and total concentric and eccentric work of the knee flexors (p < 0.046) following repeated maximal voluntary contractions. Many of these acute caffeine effects were still prevalent following chronic exposure to caffeine throughout the intervention. The training intervention resulted in significant improvements in upper and lower body one-repetition maximum strength (p < 0.001). For the most part, the effect of the training intervention was equivalent in both the caffeine and placebo groups, despite a small but significant increase (p < 0.037) in the total work performed in the participants that consumed caffeine across the course of the intervention. These results infer that caffeine may be beneficial to evoke acute improvements in muscular strength, with acute effects prevalent following chronic exposure to the experimental dose. However, individuals that consumed caffeine during the intervention did not elicit superior post-intervention training- induced adaptations in muscular strength.


Assuntos
Cafeína/farmacologia , Suplementos Nutricionais , Futebol Americano , Treinamento de Força , Nível de Alerta , Cotovelo/fisiologia , Humanos , Joelho/fisiologia , Masculino , Esforço Físico/fisiologia , Placebos , Amplitude de Movimento Articular/fisiologia , Torque , Adulto Jovem
12.
Clin Oral Implants Res ; 32(11): 1274-1287, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34658084

RESUMO

OBJECTIVE: A novel implant design, the rectangular block implant (RBI), was investigated as a possible solution to the restoration of the posterior resorbed ridge. AIM: To maximally load test the osseo-integrated RBI in shear and tensile loads and relate these findings to known human masticatory loads as biomechanical proof of the study concept. MATERIALS AND METHODS: Twelve RBIs were design-manufactured and placed into posterior mandibular saddles in 3 mature greyhound dogs.-2 per left and right. After 12 weeks of healing, osseo-integration was confirmed using resonance frequency analysis (RFA) and wrench torque tests. Three bone blocks each with two RBIs were dissected and mounted in acrylic. Micro-computerized tomography (µ-CT) was performed to assess bone to implant contact (BIC), and load analysis was performed using a Universal Test System. Three force applications were conducted until failure: pull-out (tensile), buccal push from the lingual (shear) and distal push from the mesial (shear). The osteotomy sites were examined using light magnification and scanning electron microscopy (SEM). RESULTS: Pull-out, buccal and distal force failures occurred at differing levels. Post-detachment sites showed complex patterns of bone failure, including trabecular and cortical fracture, as well as shearing at varying distances from the BIC. Interfacial shear strength was calculated at 14.4 MPa. CONCLUSION: The osseo-integrated RBIs were able to withstand simulations of the demanding axially, bucco-lingually and mesio-distally oriented biomechanical challenges of the posterior saddle, under conditions of reduced bone volume. These values exceeded equivalent force components of maximal masticatory loads in humans.


Assuntos
Prótese Ancorada no Osso , Implantes Dentários , Animais , Fenômenos Biomecânicos , Cães , Mandíbula/cirurgia , Torque
13.
Am J Dent ; 34(5): 245-249, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34689446

RESUMO

PURPOSE: To determine the prevalence of non-carious cervical lesions (NCCLs) in maxillary premolars of different torques and simulated cervical stress profiles of the premolars under coincident loadings using finite element analysis (FEA). METHODS: The CBCT scans of 616 maxillary premolars from 154 subjects were retrospectively evaluated. The premolars were ascribed into low torque group (LTG) <-10.9°, medium torque group (MTG) -10.9° to -3.9°, and high torque group (HTG) >-3.9°, when the torque was referring to the occlusion plane. The prevalence of NCCLs in each group was evaluated. Then finite element models of a maxillary first premolar, its adjacent teeth and alveolar bone were established. The models were prepared with ANSYS software generating the premolars presenting different torques. The mastication scenario for the premolars in maximum intercuspation position was simulated. RESULTS: The prevalence of NCCLs was 15.7% in LTG, 7.9% in MTG and 5.5% in HTG. The prevalence of LTG was significantly higher than that of MTG (P< 0.05) and HTG (P< 0.01). As for FEA, the stresses at the buccal necks of the premolars basically increased with decrease of the torque. The tensile stress peaks were in the cemento-enamel junction in most premolars of the LTG, while in the middle of the crowns in premolars of MTG and HTG. CLINICAL SIGNIFICANCE: Low torque with excessive lingual inclination is a risk factor for NCCLs of maxillary premolars, and excessive tensile stress concentration in buccal necks during mastication may be responsible for that.


Assuntos
Colo do Dente , Dente Pré-Molar/diagnóstico por imagem , Humanos , Estudos Retrospectivos , Fatores de Risco , Colo do Dente/diagnóstico por imagem , Torque
14.
J Int Soc Sports Nutr ; 18(1): 60, 2021 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-34503541

RESUMO

BACKGROUND: Numerous studies have demonstrated the efficacy of creatine supplementation for improvements in exercise performance. Few studies, however, have examined the effects of phosphocreatine supplementation on exercise performance. Furthermore, while polyphenols have antioxidant and anti-inflammatory properties, little is known regarding the influence of polyphenol supplementation on muscular strength, power, and endurance. Thus, the purpose of the present study was to compare the effects of 28 days of supplementation with phosphocreatine disodium salts plus blueberry extract (PCDSB), creatine monohydrate (CM), and placebo on measures of muscular strength, power, and endurance. METHODS: Thirty-three men were randomly assigned to consume either PCDSB, CM, or placebo for 28 days. Peak torque (PT), average power (AP), and percent decline for peak torque (PT%) and average power (AP%) were assessed from a fatigue test consisting of 50 maximal, unilateral, isokinetic leg extensions at 180°·s- 1 before and after the 28 days of supplementation. Individual responses were assessed to examine the proportion of subjects that exceeded a minimal important difference (MID). RESULTS: The results demonstrated significant (p < 0.05) improvements in PT for the PCDSB and CM groups from pre- (99.90 ± 22.47 N·m and 99.95 ± 22.50 N·m, respectively) to post-supplementation (119.22 ± 29.87 N·m and 111.97 ± 24.50 N·m, respectively), but no significant (p = 0.112) change for the placebo group. The PCDSB and CM groups also exhibited significant improvements in AP from pre- (140.18 ± 32.08 W and 143.42 ± 33.84 W, respectively) to post-supplementation (170.12 ± 42.68 W and 159.78 ± 31.20 W, respectively), but no significant (p = 0.279) change for the placebo group. A significantly (p < 0.05) greater proportion of subjects in the PCDSB group exceeded the MID for PT compared to the placebo group, but there were no significant (p > 0.05) differences in the proportion of subjects exceeding the MID between the CM and placebo groups or between the CM and PCDSB groups. CONCLUSIONS: These findings indicated that for the group mean responses, 28 days of supplementation with both PCDSB and CM resulted in increases in PT and AP. The PCDSB, however, may have an advantage over CM when compared to the placebo group for the proportion of individuals that respond favorably to supplementation with meaningful increases in muscular strength.


Assuntos
Força Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Fosfocreatina/farmacologia , Resistência Física/efeitos dos fármacos , Extratos Vegetais/farmacologia , Mirtilos Azuis (Planta)/química , Creatina , Suplementos Nutricionais , Método Duplo-Cego , Humanos , Masculino , Torque , Adulto Jovem
16.
BMC Musculoskelet Disord ; 22(1): 829, 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34579696

RESUMO

BACKGROUND: In aging, muscle stiffness is considered as one of the factors associated with the reduction of force generation capability. There have been inconsistent findings on age-related alteration in the passive stiffness of quadriceps muscle in the female adults. Thus, the aim of this study was to determine the effect of aging on the shear moduli of the superficial muscle heads of the quadriceps and to explore its relationship with knee extension force. METHODS: Passive shear moduli of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) were measured at rest using shear wave elastography in 20 young and 20 senior female adults. Measurements were repeated at four knee joint positions, that is, 30°, 60°, 90°, and 105° of knee flexion. Maximal isometric voluntary knee extension force was assessed at 30°, 60°, and 90° of knee flexion. RESULTS: As per our findings, senior adults were determined to have significantly higher passive muscle shear moduli in the RF (by 34% - 68%; all p < 0.05) and the VL muscle heads (by 13%-16%, all p < 0.05) at and beyond 60° of knee flexion. Age-related increase in the VM was evident at 105° knee flexion (by11%, p = 0.020). The RF shear modulus was negatively correlated to the maximal isometric voluntary contraction force measured at 60° (r = - 0.485, p = 0.030) in senior adults. CONCLUSIONS: Senior female adults had greater passive stiffness at the superficial muscle heads of the quadriceps muscles when measured at long muscle length. Among the senior female adults, the passive stiffness of RF has been determined to have a negative association with the knee extensor force only at 60° knee flexion. No significant association was noted for other angles and muscles.


Assuntos
Contração Isométrica , Músculo Quadríceps , Adulto , Eletromiografia , Feminino , Humanos , Joelho , Articulação do Joelho/diagnóstico por imagem , Músculo Esquelético/diagnóstico por imagem , Músculo Quadríceps/diagnóstico por imagem , Torque
17.
Soft Matter ; 17(39): 8858-8866, 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34541594

RESUMO

Bacterial biofilms cost an enormous amount of resources in the health, medical, and industrial sectors. To understand early biofilm formation, beginning from planktonic states of active suspensions (such as Escherichia coli) to micro-colonization, it is vital to study the mechanics of cell accumulation near surfaces and subsequent deposition. Variability in bacterial motion strategies and the presence of taxis fields make the problem even more multifaceted. In this study, analytical expressions for the density and angular distributions, mean orientation, and deposition rates in such bacterial suspensions are derived, with and without the effects of external guiding or taxis fields. The derived results are closely verified by simulations of confined active particles using run-and-tumble statistics from multiple past experiments and utilizing a preferential sticking probability model for deposition. The behavioral changes in cell running strategies are modeled by varying the run-time distribution from an exponential to a heavy-tailed one. It is found that the deposition rates can be altered significantly by a guiding torque but are less affected by a change in the cell running behavior. However, both the mechanisms alter the pair correlation function of the deposited structures. The factor behind the changes in the architecture of deposited biomass under a torque generating guiding field turns out to be an asymmetrical rotational drift of planktonic cells, which can be an important physical mechanism behind the organization in confined active particle suspensions.


Assuntos
Escherichia coli , Corrida , Movimento (Física) , Suspensões , Torque
18.
J Prosthodont Res ; 65(4): 489-494, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34470982

RESUMO

Purpose This in vitro study aimed to evaluate the effectiveness of a sealing agent in sealing the abutment/implant interface and the preload maintenance of retaining screws after mechanical cycling.Methods Six groups (n = 12) were evaluated according to the abutment/implant system (external-hexagon implant and UCLA abutments, EHU; Morse taper implant and UCLA abutments, MTU; and Morse taper implant and flexcone abutments, MTF) and the presence of an anaerobic gel sealing agent (control group, no sealing agent; experimental group, sealing agent). Toluidine blue (0.7 µL) was inserted into each implant and the abutments were attached to the implants using a digital torque wrench to evaluate the sealing of the abutment/implant interface. The specimens were tested through mechanical cycling (1 × 106 cycles, 2 Hz, and 130 N). Dye release from the abutment/implant interface was analyzed using a spectrophotometer, and the reverse torque values were obtained using a digital wrench. Reverse torque and dye release data were measured after mechanical cycling and analyzed using ANOVA and Tukey's test (α =.05).Results All experimental groups showed higher reverse torque values than the control groups (P <.05). In general, the MTU and MTF experimental groups, as well as the MTF control group, showed no significant dye release at different periods (P >.05).Conclusions The use of a sealing agent improved the preload maintenance of screw-retained implant-supported prostheses. The sealing agent was effective in sealing the Morse taper connection.


Assuntos
Dente Suporte , Implantes Dentários , Prótese Dentária Fixada por Implante , Análise do Estresse Dentário , Torque
19.
J Vis Exp ; (175)2021 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-34542541

RESUMO

Reliable assessment of skeletal muscle strength is arguably the most important outcome measure in neuromuscular and musculoskeletal disease and injury studies, particularly when evaluating regenerative therapies' efficacy. Additionally, a critical aspect of translating many regenerative therapies is the demonstration of scalability and effectiveness in a large animal model. Various physiological preparations have been established to evaluate intrinsic muscle function properties in basic science studies, primarily in small animal models. The practices may be categorized as: in vitro (isolated fibers, fiber bundles, or whole muscle), in situ (muscle with intact vascularization and innervation but distal tendon attached to a force transducer), and in vivo (structures of the muscle or muscle unit remain intact). There are strengths and weaknesses to each of these preparations; however, a clear advantage of in vivo strength testing is the ability to perform repeated measurements in the same animal. Herein, the materials and methods to reliably assess isometric torque produced by the hindlimb dorsiflexor muscles in vivo in response to standard peroneal electrical stimulation in anesthetized pigs are presented.


Assuntos
Força Muscular , Músculo Esquelético , Animais , Membro Posterior , Contração Isométrica , Extremidade Inferior , Suínos , Torque
20.
Artigo em Inglês | MEDLINE | ID: mdl-34501883

RESUMO

The purpose of this study is to establish the absolute reliability between hand-held dynamometers (HHDs) and concurrent validity between HHDs and isokinetic dynamometers (IDs) in shoulder rotator strength assessment. The Medline, CINAHL, and Central databases were searched for relevant studies up to July 2020. Absolute reliability was determined by test-retest studies presenting standard error of measurement (SEM%) and/or minimal detectable change (MDC%) expressed as percentage of the mean. Studies considering intra-class correlation coefficient (ICC) between IDs and HHDs were considered for concurrent validity. The risk of bias and the methodological quality were evaluated according to COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN). Thirteen studies were included in the meta-analysis. Shoulder internal rotator strength assessment MDC% was 0.78%, 95% confidence interval (CI) -5.21 to 3.66, while shoulder external rotators MDC% was 3.29%, CI -2.69 to 9.27. ICC between devices was 0.94, CI (0.91 to 0.96) for shoulder internal rotators and 0.92, IC (0.88 to 0.97) for shoulder external rotators. Very high correlation was found for shoulder rotator torque assessment between HHDs and IDs. The COSMIN checklist classified the selected studies as adequate and inadequate.


Assuntos
Gerenciamento de Dados , Ombro , Humanos , Dinamômetro de Força Muscular , Reprodutibilidade dos Testes , Torque
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