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Sample records for bite force measurements

  1. Novel Low-Cost Sensor for Human Bite Force Measurement

    Directory of Open Access Journals (Sweden)

    Jarred Fastier-Wooller

    2016-08-01

    Full Text Available This paper presents the design and development of a low cost and reliable maximal voluntary bite force sensor which can be manufactured in-house by using an acrylic laser cutting machine. The sensor has been designed for ease of fabrication, assembly, calibration, and safe use. The sensor is capable of use within an hour of commencing production, allowing for rapid prototyping/modifications and practical implementation. The measured data shows a good linear relationship between the applied force and the electrical resistance of the sensor. The output signal has low drift, excellent repeatability, and a large measurable range of 0 to 700 N. A high signal-to-noise response to human bite forces was observed, indicating the high potential of the proposed sensor for human bite force measurement.

  2. Bite force and state of dentition.

    Science.gov (United States)

    Helkimo, E; Carlsson, G E; Helkimo, M

    1977-01-01

    The maximal bite force and the strength of the finger-thumb grip of 125 Skolt Lapps, aged 15 to 65, was measured with a specially devised apparatus. The bite force was measured with the biting fork placed between the first molars and between the incisors, respectively. The finger-thumb grip was measured by letting the subject press the prongs of the fork between the thumb and forefinger of each hand as hard as possible. The range of inter-individual variation of the maximal bite force and finger-thumb grip was great. The mean values were higher for the males than for the females. In the males the maximal bite force thus measured in the molar region was 39 kg (382 N) and 18 kg (176 N) in the incisor region. The corresponding values for the females were 22 kg (216 N) and 11 kg (108 N). The finger-thumb grip strength for males was, on the average, 10 kg (98 N); that of the females, 7 KG (69 N). The average difference in bite force between the men and the women was larger in the group with natural teeth than in the one with complete dentures. The values found for the bite force decreased with increasing age, especially for the females. Most of this reduction with increasing age was probably due to the age-dependent deterioration of the dentition. In both sexes the bite force was notably smaller among the denture wearers than among the dentate persons. The number of natural teeth varied closely with the bite force, i.e. the greater number of natural teeth the greater the bite force.

  3. Bite Force and Pattern Measurements for Dental Pain Assessment in the Rat

    Science.gov (United States)

    Khan, Junad; Benoliel, Rafael; Herzberg, Uri; Mannes, Andrew J.; Caudle, Robert M.; Young, Andrew; Eliav, Eli

    2008-01-01

    We present simple method to assess dental pain in the awake rat. Using a sensitive strain gauge we examined changes in bite strength and bite pattern in rats following dental injury. Rats with dental injury displayed a significant reduction in mean peak bite strength and an altered bite-cluster pattern. Both changes in the dental injury rats were reversed by an analgesic dose of morphine, and this could be reversed with naloxone. These changes were not observed in naive control animals. This simple method significantly improves our ability to evaluate dental pain syndromes. PMID:18926882

  4. Can masticatory electromyography be normalised to submaximal bite force?

    Science.gov (United States)

    Crawford, S R; Burden, A M; Yates, J M; Zioupos, P; Winwood, K

    2015-05-01

    The combination of bite force and jaw muscle electromyography (EMG) provides an insight into the performance of the stomatognathic system, especially in relation to dynamic movement tasks. Literature has extensively investigated possible methods for normalising EMG data encapsulating many different approaches. However, bite force literature trends towards normalising EMG to a maximal voluntary contraction (MVC), which could be difficult for ageing populations or those with poor dental health or limiting conditions such as temporomandibular disorder. The objectives of this study were to (i) determine whether jaw-closing muscle activity is linearly correlated with incremental submaximal and maximal bite force levels and (ii) assess whether normalising maximal and submaximal muscle activity to that produced when performing a low submaximal bite force (20 N) improves repeatability of EMG values. Thirty healthy adults (15 men, 15 women; mean age 21 ± 1·2 years) had bite force measurements obtained using a custom-made button strain gauge load cell. Masseter and anterior temporalis muscle activities were collected bilaterally using surface EMG sensors whilst participants performed maximal biting and three levels of submaximal biting. Furthermore, a small group (n = 4 females) were retested for reliability purposes. Coefficients of variation and intra-class correlation coefficients showed markedly improved reliability when EMG data were normalised compared to non-normalised. This study shows that jaw muscle EMG may be successfully normalised to a very low bite force. This may open possibilities for comparisons between at-risk sample groups that may otherwise find it difficult to produce maximal bite force values.

  5. Feeding biomechanics and theoretical calculations of bite force in bull sharks (Carcharhinus leucas) during ontogeny.

    Science.gov (United States)

    Habegger, Maria L; Motta, Philip J; Huber, Daniel R; Dean, Mason N

    2012-12-01

    Evaluations of bite force, either measured directly or calculated theoretically, have been used to investigate the maximum feeding performance of a wide variety of vertebrates. However, bite force studies of fishes have focused primarily on small species due to the intractable nature of large apex predators. More massive muscles can generate higher forces and many of these fishes attain immense sizes; it is unclear how much of their biting performance is driven purely by dramatic ontogenetic increases in body size versus size-specific selection for enhanced feeding performance. In this study, we investigated biting performance and feeding biomechanics of immature and mature individuals from an ontogenetic series of an apex predator, the bull shark, Carcharhinus leucas (73-285cm total length). Theoretical bite force ranged from 36 to 2128N at the most anterior bite point, and 170 to 5914N at the most posterior bite point over the ontogenetic series. Scaling patterns differed among the two age groups investigated; immature bull shark bite force scaled with positive allometry, whereas adult bite force scaled isometrically. When the bite force of C. leucas was compared to those of 12 other cartilaginous fishes, bull sharks presented the highest mass-specific bite force, greater than that of the white shark or the great hammerhead shark. A phylogenetic independent contrast analysis of anatomical and dietary variables as determinants of bite force in these 13 species indicated that the evolution of large adult bite forces in cartilaginous fishes is linked predominantly to the evolution of large body size. Multiple regressions based on mass-specific standardized contrasts suggest that the evolution of high bite forces in Chondrichthyes is further correlated with hypertrophication of the jaw adductors, increased leverage for anterior biting, and widening of the head. Lastly, we discuss the ecological significance of positive allometry in bite force as a possible

  6. Bite force in patients with functional disturbances of the masticatory system.

    Science.gov (United States)

    Helkimo, E; Carlsson, G E; Carmeli, Y

    1975-10-01

    In thirty patients (24 women and 6 men) treated because of dysfunction of the masticatory system at the department of Stomatognathic Physiology, University of Gothenburg, bite force was registered before, during and after treatment had been completed. In the controls, thirty-six dental students and trainee dental nurses, with no dysfunction of the masticatory system, bite force was registered on two occasions. Bite force was measured between the first molars on each side and between the central incisors. Also finger force was registered. The force measurements were made at five different levels, increasing from very weak to maximum force. Repeated tests of bite force in the control group, made at intervals of about 1 week, gave almost identical results. Bite force in the patient group was lower than in the control group at the first registration but increased with palliation of the symptoms during treatment. There was no significant difference in bite force between the affected and the unaffected side.

  7. Clinical significance of isometric bite force versus electrical activity in temporal and masseter muscles

    DEFF Research Database (Denmark)

    Bakke, Merete; Michler, L; Han, K;

    1989-01-01

    significant with respect to unilateral, but not to bilateral force measurements. Only in the masseter muscle was strength of dynamic contractions during chewing significantly correlated to bite force. With the present method it was demonstrated that unilateral bite force is a simple clinical indicator...

  8. Bite force evaluation in subjects with cleft lip and palate

    Directory of Open Access Journals (Sweden)

    Carla Renata Sipert

    2009-04-01

    Full Text Available The purpose of this study was to evaluate the masticatory function of subjects with cleft lip and palate by analyzing the bite force developed by these individuals. Bite force was evaluated in a group of 27 individuals with repaired unilateral cleft lip and palate (14 males and 13 females - aged 18-26 years and compared to the data achieved from a group of 20 noncleft subjects (10 males and 10 females - aged 18-26 years. Measurement was achieved on three positions within the dental arch (incisors, right molars and left molars, three times at each position considering the highest value for each one. Statistical analysis was performed by ANOVA and Mann-Whitney test ( α = 5%. There was a significant deficit in bite force in male individuals with cleft lip and palate compared to the male control group (p=0.02, p=0.004, p=0.003 for incisors, right and left molars, respectively. For the female group, the difference was not statistically significant (p=0.79, p=0.06, p=0.47. In the group of individuals with clefts, 92.6% were under orthodontic treatment, which could be a reason for the present findings, since it can decrease the bite force more remarkably in males than in females. In conclusion, the bite force is significantly reduced in men when comparing the cleft group to the noncleft group. In females, this reduction was not significant in the same way. However, the main reason for this reduction and for the different behavior between genders should be further investigated.

  9. BITE-FORCE ENDURANCE IN PATIENTS WITH TEMPOROMANDIBULAR-JOINT OSTEOARTHROSIS AND INTERNAL DERANGEMENT

    NARCIS (Netherlands)

    STEGENGA, B; BROEKHUIJSEN, ML; DEBONT, LGM; VANWILLIGEN, JD

    1992-01-01

    The aim of this study was to investigate the potential clinical relevance of testing bite force endurance in patients with articular temporomandibular disorders. The endurance of a 50 N bite force was measured in 51 patients with painful temporomandibular joint disorders. The results were compared t

  10. Comparative analysis of methods for determining bite force in the spiny dogfish Squalus acanthias.

    Science.gov (United States)

    Huber, Daniel Robert; Motta, Philip Jay

    2004-01-01

    Many studies have identified relationships between the forces generated by the cranial musculature during feeding and cranial design. Particularly important to understanding the diversity of cranial form amongst vertebrates is knowledge of the generated magnitudes of bite force because of its use as a measure of ecological performance. In order to determine an accurate morphological proxy for bite force in elasmobranchs, theoretical force generation by the quadratomandibularis muscle of the spiny dogfish Squalus acanthias was modeled using a variety of morphological techniques, and lever-ratio analyses were used to determine resultant bite forces. These measures were compared to in vivo bite force measurements obtained with a pressure transducer during tetanic stimulation experiments of the quadratomandibularis. Although no differences were found between the theoretical and in vivo bite forces measured, modeling analyses indicate that the quadratomandibularis muscle should be divided into its constituent divisions and digital images of the cross-sections of these divisions should be used to estimate cross-sectional area when calculating theoretical force production. From all analyses the maximum bite force measured was 19.57 N. This relatively low magnitude of bite force is discussed with respect to the ecomorphology of the feeding mechanism of S. acanthias to demonstrate the interdependence of morphology, ecology, and behavior in organismal design. PMID:14695686

  11. Effect of gender, facial dimensions, body mass index and type of functional occlusion on bite force

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    Duygu Koç

    2011-06-01

    Full Text Available OBJECTIVE: Some factors such as gender, age, craniofacial morphology, body structure, occlusal contact patterns may affect the maximum bite force. Thus, the purposes of this study were to determine the mean maximum bite force in individuals with normal occlusion, and to examine the effect of gender, facial dimensions, body mass index (BMI, type of functional occlusion (canine guidance and group function occlusion and balancing side interferences on it. MATERIAL AND METHODS: Thirty-four individuals aged 19-20 years-old were selected for this study. Maximum bite force was measured with strain-gauge transducers at first molar region. Facial dimensions were defined by standardized frontal photographs as follows: anterior total facial height (ATFH, bizygomathic facial width (BFW and intergonial width (IGW. BMI was calculated using the equation weight/height². The type of functional occlusion and the balancing side interferences of the subjects were identified by clinical examination. RESULTS: Bite force was found to be significantly higher in men than women (p0.05. BMI and bite force correlation was not statistically significant (p>0.05. The average bite force did not differ in subjects with canine guidance or group function occlusion and in the presence of balancing side interferences (p>0.05. CONCLUSIONS: Data suggest that bite force is affected by gender. However, BMI, type of functional occlusion and the presence of balancing side interferences did not exert a meaningful influence on bite force. In addition, transverse facial dimensions showed correlation with bite force in only men.

  12. EMG, bite force, and elongation of the masseter muscle under isometric voluntary contractions and variations of vertical dimension.

    Science.gov (United States)

    Manns, A; Miralles, R; Palazzi, C

    1979-12-01

    The relation EMG activity, bite force, and muscular elongation was studied in eight subjects with complete natural dentition during isometric contractions of the masseter muscle, measured from 7 mm to almost maximum jaw opening. EMG was registered with superficial electrodes and bite force with a gnathodynamometer. In series 1, recordings of EMG activity maintaining bite force constant (10 and 20 kg) show that EMG is high when the bite opening is 7 mm, decreases from 15 to 20 mm, and then increases again as jaw opening approaches maximum opening. In series 2, recordings of bite force maintaining EMG constant show that bite force increases up to a certain range of jaw opening (around 15 to 20 mm) and then decreases as we approach maximum jaw opening. Results show that there is for each experimental subject a physiologically optimum muscular elongation of major efficiency where the masseter develops highest muscular force with least EMG activity.

  13. The effects of biting and pulling on the forces generated during feeding in the Komodo dragon (Varanus komodoensis.

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    Domenic C D'Amore

    Full Text Available In addition to biting, it has been speculated that the forces resulting from pulling on food items may also contribute to feeding success in carnivorous vertebrates. We present an in vivo analysis of both bite and pulling forces in Varanus komodoensis, the Komodo dragon, to determine how they contribute to feeding behavior. Observations of cranial modeling and behavior suggest that V. komodoensis feeds using bite force supplemented by pulling in the caudal/ventrocaudal direction. We tested these observations using force gauges/transducers to measure biting and pulling forces. Maximum bite force correlates with both body mass and total body length, likely due to increased muscle mass. Individuals showed consistent behaviors when biting, including the typical medial-caudal head rotation. Pull force correlates best with total body length, longer limbs and larger postcranial motions. None of these forces correlated well with head dimensions. When pulling, V. komodoensis use neck and limb movements that are associated with increased caudal and ventral oriented force. Measured bite force in Varanus komodoensis is similar to several previous estimations based on 3D models, but is low for its body mass relative to other vertebrates. Pull force, especially in the ventrocaudal direction, would allow individuals to hunt and deflesh with high success without the need of strong jaw adductors. In future studies, pull forces need to be considered for a complete understanding of vertebrate carnivore feeding dynamics.

  14. Chewing side, bite force symmetry, and occlusal contact area of subjects with different facial vertical patterns

    Directory of Open Access Journals (Sweden)

    Simone Guimarães Farias Gomes

    2011-10-01

    Full Text Available Craniofacial dimensions influence oral functions; however, it is not known whether they are associated with function asymmetry. The objective of this study was to evaluate chewing side preference and lateral asymmetry of occlusal contact area and bite force of individuals with different craniofacial patterns. Seventy-eight dentate subjects were divided into 3 groups according to the VERT index as follows: (1 mesofacial, (2 brachyfacial and (3 dolichofacial. Chewing side preference was evaluated using jaw tracking equipment, occlusal contact area was measured by silicon registration of posterior teeth, and bite force was measured unilaterally on molar regions using 2.25 mm-thick sensors. Statistical analysis was performed using ANOVA on Ranks, Student's t-test, and Mann-Whitney tests at a 5% significance level. Mesofacial, brachyfacial, and dolichofacial subjects presented more occlusal contact area on the left side. Only dolichofacial subjects showed lateral asymmetry for bite force, presenting higher force on the left side. No statistically significant differences were found for chewing side preference among all groups. Within the limitations of this study, it can be concluded that craniofacial dimensions play a role in asymmetry of bite force. ClinicalTrials.gov ID: NCT01286363.

  15. Contribution of the digastric muscles to the control of bite force in man

    NARCIS (Netherlands)

    VanWilligen, JD; Slager, GEC; Broekhuijsen, ML

    1997-01-01

    The contribution of the (co-contracting) digastric muscles to the rapid decline in bite-force magnitude after unloading of a static bite was investigated by asking participants to perform two different biting tasks with sudden unloading, and correlating the degree of co-contraction of the digastrics

  16. Risk factors for low molar bite force in adult orthodontic patients

    DEFF Research Database (Denmark)

    Andersen, Malene Krogh; Sonnesen, Ane Liselotte

    2013-01-01

    The aim was to analyse which parameters in a standard orthodontic material are most important for identifying factors for low bite force. Such analyses have not previously been reported in adult orthodontic patients. The sample comprised 95 adults (67 females and 28 males) aged 18-55 years...... sequentially admitted for conventional orthodontic treatment. All subjects had moderate to severe malocclusions. Bite force was measured by a pressure transducer, craniofacial dimensions and head posture were measured on profile radiographs, number of teeth in contact were evaluated with a plastic strip...... showed that gender (P orthodontic patients (R(2) = 0.32). The results showed that particularly women with TMD symptoms and an increased mandibular plane...

  17. Comparative Evaluation of Maximum Bite Force in Dentulous and Edentulous Individuals with Different Facial Forms

    OpenAIRE

    Tripathi, Gaurav; A.A., Ponnanna; Rajwadha, Nishant; Chhaparia, Nidhi; Sharma, Abhishek; Anant, Mahendra

    2014-01-01

    Purpose: The purpose of this study was to evaluate the mean maximum bite force in dentulous and edentulous individuals with Angle’s class-I occlusion and to assess the effect of different facial forms such as Square, Square-tapering, tapering and ovoid on the biting force.

  18. Novel System for Bite-Force Sensing and Monitoring Based on Magnetic Near Field Communication

    Science.gov (United States)

    Lantada, Andres Diaz; Bris, Carlos González; Morgado, Pilar Lafont; Maudes, Jesús Sanz

    2012-01-01

    Intraoral devices for bite-force sensing have several applications in odontology and maxillofacial surgery, as bite-force measurements provide additional information to help understand the characteristics of bruxism disorders and can also be of help for the evaluation of post-surgical evolution and for comparison of alternative treatments. A new system for measuring human bite forces is proposed in this work. This system has future applications for the monitoring of bruxism events and as a complement for its conventional diagnosis. Bruxism is a pathology consisting of grinding or tight clenching of the upper and lower teeth, which leads to several problems such as lesions to the teeth, headaches, orofacial pain and important disorders of the temporomandibular joint. The prototype uses a magnetic field communication scheme similar to low-frequency radio frequency identification (RFID) technology (NFC). The reader generates a low-frequency magnetic field that is used as the information carrier and powers the sensor. The system is notable because it uses an intra-mouth passive sensor and an external interrogator, which remotely records and processes information regarding a patient's dental activity. This permits a quantitative assessment of bite-force, without requiring intra-mouth batteries, and can provide supplementary information to polysomnographic recordings, current most adequate early diagnostic method, so as to initiate corrective actions before irreversible dental wear appears. In addition to describing the system's operational principles and the manufacture of personalized prototypes, this report will also demonstrate the feasibility of the system and results from the first in vitro and in vivo trials. PMID:23112669

  19. Novel System for Bite-Force Sensing and Monitoring Based on Magnetic Near Field Communication

    Directory of Open Access Journals (Sweden)

    Jesús Sanz Maudes

    2012-08-01

    Full Text Available Intraoral devices for bite-force sensing have several applications in odontology and maxillofacial surgery, as bite-force measurements provide additional information to help understand the characteristics of bruxism disorders and can also be of help for the evaluation of post-surgical evolution and for comparison of alternative treatments. A new system for measuring human bite forces is proposed in this work. This system has future applications for the monitoring of bruxism events and as a complement for its conventional diagnosis. Bruxism is a pathology consisting of grinding or tight clenching of the upper and lower teeth, which leads to several problems such as lesions to the teeth, headaches, orofacial pain and important disorders of the temporomandibular joint. The prototype uses a magnetic field communication scheme similar to low-frequency radio frequency identification (RFID technology (NFC. The reader generates a low-frequency magnetic field that is used as the information carrier and powers the sensor. The system is notable because it uses an intra-mouth passive sensor and an external interrogator, which remotely records and processes information regarding a patient’s dental activity. This permits a quantitative assessment of bite-force, without requiring intra-mouth batteries, and can provide supplementary information to polysomnographic recordings, current most adequate early diagnostic method, so as to initiate corrective actions before irreversible dental wear appears. In addition to describing the system’s operational principles and the manufacture of personalized prototypes, this report will also demonstrate the feasibility of the system and results from the first in vitro and in vivo trials.

  20. Ontogenetic Scaling of Theoretical Bite Force in Southern Sea Otters (Enhydra lutris nereis).

    Science.gov (United States)

    Law, Chris J; Young, Colleen; Mehta, Rita S

    2016-01-01

    Sexual dimorphism attributed to niche divergence is often linked to differentiation between the sexes in both dietary resources and characters related to feeding and resource procurement. Although recent studies have indicated that southern sea otters (Enhydra lutris nereis) exhibit differences in dietary preferences as well as sexual dimorphism in skull size and shape, whether these intersexual differences translate to differentiation in feeding performances between the sexes remains to be investigated. To test the hypothesis that scaling patterns of bite force, a metric of feeding performance, differ between the sexes, we calculated theoretical bite forces for 55 naturally deceased male and female southern sea otters spanning the size ranges encountered over ontogeny. We then used standardized major axis regressions to simultaneously determine the scaling patterns of theoretical bite forces and skull components across ontogeny and assess whether these scaling patterns differed between the sexes. We found that positive allometric increases in theoretical bite force resulted from positive allometric increases in physiological cross-sectional area for the major jaw adductor muscle and mechanical advantage. Closer examination revealed that allometric increases in temporalis muscle mass and relative allometric decreases in out-lever lengths are driving these patterns. In our analysis of sexual dimorphism, we found that scaling patterns of theoretical bite force and morphological traits do not differ between the sexes. However, adult sea otters differed in their absolute bite forces, revealing that adult males exhibited greater bite forces as a result of their larger sizes. We found intersexual differences in biting ability that provide some support for the niche divergence hypothesis. Continued work in this field may link intersexual differences in feeding functional morphology with foraging ecology to show how niche divergence has the potential to reinforce sexual

  1. Ontogenetic Scaling of Theoretical Bite Force in Southern Sea Otters (Enhydra lutris nereis).

    Science.gov (United States)

    Law, Chris J; Young, Colleen; Mehta, Rita S

    2016-01-01

    Sexual dimorphism attributed to niche divergence is often linked to differentiation between the sexes in both dietary resources and characters related to feeding and resource procurement. Although recent studies have indicated that southern sea otters (Enhydra lutris nereis) exhibit differences in dietary preferences as well as sexual dimorphism in skull size and shape, whether these intersexual differences translate to differentiation in feeding performances between the sexes remains to be investigated. To test the hypothesis that scaling patterns of bite force, a metric of feeding performance, differ between the sexes, we calculated theoretical bite forces for 55 naturally deceased male and female southern sea otters spanning the size ranges encountered over ontogeny. We then used standardized major axis regressions to simultaneously determine the scaling patterns of theoretical bite forces and skull components across ontogeny and assess whether these scaling patterns differed between the sexes. We found that positive allometric increases in theoretical bite force resulted from positive allometric increases in physiological cross-sectional area for the major jaw adductor muscle and mechanical advantage. Closer examination revealed that allometric increases in temporalis muscle mass and relative allometric decreases in out-lever lengths are driving these patterns. In our analysis of sexual dimorphism, we found that scaling patterns of theoretical bite force and morphological traits do not differ between the sexes. However, adult sea otters differed in their absolute bite forces, revealing that adult males exhibited greater bite forces as a result of their larger sizes. We found intersexual differences in biting ability that provide some support for the niche divergence hypothesis. Continued work in this field may link intersexual differences in feeding functional morphology with foraging ecology to show how niche divergence has the potential to reinforce sexual

  2. INFLUENCE OF VISUAL FEEDBACK ON HUMAN ISOMETRIC BITE-FORCE TREMOR

    NARCIS (Netherlands)

    BROEKHUIJSEN, ML; VANWILLIGEN, JD

    1994-01-01

    In contrast to recent reports, during an isometric short forceful bite, visual feedback had a significant influence on the force tremor spectrum. The value of a 'half-value frequency', being the frequency f1/2 at which, with increasing frequency, the amplitude of the spectrum for the first time drop

  3. Forças de mordida relacionadas a próteses parciais removíveis inferiores Biting forces related to partially removable mandibular dentures

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    Eduardo Piza PELLIZZER

    1998-10-01

    Full Text Available A pesquisa teve como objetivo determinar as forças de mordida de 73 indivíduos, por meio de um gnatodinamômetro. Os pacientes eram portadores de próteses parciais removíveis inferiores classes I, II ou III. A arcada antagonista era prótese, parcial removível ou fixa, ou total. Os resultados permitiram concluir que: as selas de extremidade livre, principalmente em suas posições extremas, conduziram a forças de mordida muito baixas; o envolvimento de prótese total, também, conduziu a forças de mordida baixas; o sexo masculino alcançou valores maiores que o feminino; com prótese parcial removível classe III, os dentes naturais molares e pré-molares desenvolveram valores maiores do que com classes I e II.The purpose of this study was to determine the biting forces of individuals wearing classes I, II or III partially removable mandibular dentures. Upper jaws presented fixed bridges, classes I, II or III partially removable dentures, or complete dentures. Measurements of biting forces were obtained by a gnathodynamometer. The conclusions were: classes I and II presented low biting forces, specially far from the last abutment tooth; when the opposite arcade was a complete denture, biting forces were low; males presented higher biting forces than females; natural molars and bicuspids presented higher biting forces with class III than with classes I or II.

  4. Maximum bite force at age 70 years predicts all-cause mortality during the following 13 years in Japanese men.

    Science.gov (United States)

    Iwasaki, M; Yoshihara, A; Sato, N; Sato, M; Taylor, G W; Ansai, T; Ono, T; Miyazaki, H

    2016-08-01

    There is limited information on the impact of oral function on mortality among older adults. The aim of this prospective cohort study was to examine whether an objective measure of oral function, maximum bite force (MBF), is associated with mortality in older adults during a 13-year follow-up period. Five hundred and fifty-nine community-dwelling Japanese (282 men and 277 women) aged 70 years at baseline were included in the study. Medical and dental examinations and a questionnaire survey were conducted at baseline. Maximum bite force was measured using an electronic recording device (Occlusal Force-Meter GM10). Follow-up investigation to ascertain vital status was conducted 13 years after baseline examinations. Survival rates among MBF tertiles were compared using Cox proportional hazards regression models stratified by sex. There were a total of 111 deaths (82 events for men and 29 for women). Univariable analysis revealed that male participants in the lower MBF tertile had increased risk of all-cause mortality [hazard ratio (HR) = 1·94, 95% confidence interval (CI) = 1·13-3·34] compared with those in the upper MBF tertile. This association remained significant after adjustment for confounders (adjusted HR = 1·84, 95% CI = 1·07-3·19). Conversely, no association between MBF and all-cause mortality was observed in female participants. Maximum bite force was independently associated with all-cause mortality in older Japanese male adults. These data provide additional evidence for the association between oral function and geriatric health. PMID:27084614

  5. Chewing side, bite force symmetry, and occlusal contact area of subjects with different facial vertical patterns

    OpenAIRE

    Simone Guimarães Farias Gomes; William Custodio; Fernanda Faot; Altair Antoninha Del Bel Cury; Renata Cunha Matheus Rodrigues Garcia

    2011-01-01

    Craniofacial dimensions influence oral functions; however, it is not known whether they are associated with function asymmetry. The objective of this study was to evaluate chewing side preference and lateral asymmetry of occlusal contact area and bite force of individuals with different craniofacial patterns. Seventy-eight dentate subjects were divided into 3 groups according to the VERT index as follows: (1) mesofacial, (2) brachyfacial and (3) dolichofacial. Chewing side preference was eval...

  6. Efficacy of aerial spray applications using fuselage booms on Air Force C-130H aircraft against mosquitoes and biting midges.

    Science.gov (United States)

    Breidenbaugh, Mark S; Haagsma, Karl A; Wojcik, George M; De Szalay, Ferenc A

    2009-12-01

    The effectiveness of a novel fuselage boom configuration was tested with flat-fan nozzles on U.S. Air Force C-130H aircraft to create ultra-low volume sprays to control mosquitoes (Culicidae) and biting midges (Ceratopogonidae). The mortality of mosquitoes and biting midges in bioassay cages and natural populations, using the organophosphate adulticide, naled, was measured. Mosquitoes in bioassay cages had 100% mortality at 639 m downwind in all single-pass spray trials, and most trials had >90% mortality up to 1491 m downwind. Mosquito mortality was negatively correlated with distance from the spray release point (r2 = 0.38, P 90%). In wide-area operational applications, numbers of mosquitoes from natural populations 1 wk postspray were 83% (range 55%-95%), lower than prespray numbers (P < 0.05). Biting midge numbers were reduced by 86% (range 53%-97%) on average (P = 0.051) after 7 days. The results of these field trials indicate that the fuselage boom configuration on C-130H aircraft are an effective method to conduct large-scale aerial sprays during military operations and public health emergencies. PMID:20099594

  7. The relationship between skull morphology, masticatory muscle force and cranial skeletal deformation during biting.

    Science.gov (United States)

    Toro-Ibacache, Viviana; Zapata Muñoz, Víctor; O'Higgins, Paul

    2016-01-01

    The human skull is gracile when compared to many Middle Pleistocene hominins. It has been argued that it is less able to generate and withstand high masticatory forces, and that the morphology of the lower portion of the modern human face correlates most strongly with dietary characteristics. This study uses geometric morphometrics and finite element analysis (FEA) to assess the relationship between skull morphology, muscle force and cranial deformations arising from biting, which is relevant in understanding how skull morphology relates to mastication. The three-dimensional skull anatomies of 20 individuals were reconstructed from medical computed tomograms. Maximal contractile muscle forces were estimated from muscular anatomical cross-sectional areas (CSAs). Fifty-nine landmarks were used to represent skull morphology. A partial least squares analysis was performed to assess the association between skull shape and muscle force, and FEA was used to compare the deformation (strains) generated during incisor and molar bites in two individuals representing extremes of morphological variation in the sample. The results showed that only the proportion of total muscle CSA accounted for by the temporalis appears associated with skull morphology, albeit weekly. However, individuals with a large temporalis tend to possess a relatively wider face, a narrower, more vertically oriented maxilla and a lower positioning of the coronoid process. The FEAs showed that, despite differences in morphology, biting results in similar modes of deformation for both crania, but with localised lower magnitudes of strains arising in the individual with the narrowest, most vertically oriented maxilla. Our results suggest that the morphology of the maxilla modulates the transmission of forces generated during mastication to the rest of the cranium by deforming less in individuals with the ability to generate proportionately larger temporalis muscle forces.

  8. Oral Mucous Membrane Irritation Test and Biting Force Measurement of a New Denture Adhesive%义齿稳固剂的口腔黏膜刺激性及对咬合力的影响

    Institute of Scientific and Technical Information of China (English)

    肖亚伟

    2011-01-01

    目的 初步探讨自行研制的纤维素类义齿稳固剂(denture adhesive,DA)对口腔黏膜的刺激性和临床应用效果.方法 健康金黄地鼠10只随机分为2组,麻醉后,其中1组动物口腔左侧黏膜放置DA浸提液,另1组置入阳性对照材料,2组动物口腔右侧黏膜均放置阴性对照材料.分别于1、4、6、8 h后肉眼观察局部黏膜改变,并做组织切片了解组织学改变.临床测定20例患者使用DA前后,新旧全口义齿最大咬合力的变化.结果 实验动物均未出现局部及全身的不良刺激反应.所研制的稳固剂可提高新旧全口义齿的最大咬合力,但仅旧义齿使用前后差异有统计学意义(t=3.584,P<0.01).结论 所研制的DA义齿稳固剂未见对口腔黏膜的不良刺激反应,DA可提高旧义齿的最大咬合力,有较好的临床应用前景.%Objective To evaluate local and systemic response to the developed synthetic denture adhesive( DA), by oral membrane irritation test. Clinical investigation was di~ussed in this article as well. Methods Ten hamsters were used in this research and divided into 2 groups evenly. The eluates of DA and positive control materials were fixed on the left of oral membrane of each 5 hamsters' pouch separately, while the negative materials were put on the right side of all the 10 tested animals. After 1 h, 4 h, 6 h and 8 h of local and systemic observation, the local oral membrane specimens were viewed under microscope. Twenty edentulous patients with complete dentures were selected for this research also.The maximum biting force was recorded before and after application of the adhesive to all the new and old dentures. Results The results showed that there were no local or systemic abnormal response to the test material. The clinical investigation data indicated that significantly greater biting forces were generated with old dentures than with the new dentures.Conclusion The developed DA exhibited no abnormal oral mucous membrane

  9. Morphometry, Bite-Force, and Paleobiology of the Late Miocene Caiman Purussaurus brasiliensis

    Science.gov (United States)

    Aureliano, Tito; Ghilardi, Aline M.; Guilherme, Edson; Souza-Filho, Jonas P.; Cavalcanti, Mauro; Riff, Douglas

    2015-01-01

    Purussaurus brasiliensis thrived in the northwestern portion of South America during the Late Miocene. Although substantial material has been recovered since its early discovery, this fossil crocodilian can still be considered as very poorly understood. In the present work, we used regression equations based on modern crocodilians to present novel details about the morphometry, bite-force and paleobiology of this species. According to our results, an adult Purussaurus brasiliensis was estimated to reach around 12.5 m in length, weighing around 8.4 metric tons, with a mean daily food intake of 40.6 kg. It was capable of generating sustained bite forces of 69,000 N (around 7 metric tons-force). The extreme size and strength reached by this animal seems to have allowed it to include a wide range of prey in its diet, making it a top predator in its ecosystem. As an adult, it would have preyed upon large to very large vertebrates, and, being unmatched by any other carnivore, it avoided competition. The evolution of a large body size granted P. brasiliensis many advantages, but it may also have led to its vulnerability. The constantly changing environment on a large geological scale may have reduced its long-term survival, favoring smaller species more resilient to ecological shifts. PMID:25689140

  10. Bone-breaking bite force of Basilosaurus isis (Mammalia, Cetacea) from the late Eocene of Egypt estimated by finite element analysis.

    Science.gov (United States)

    Snively, Eric; Fahlke, Julia M; Welsh, Robert C

    2015-01-01

    Bite marks suggest that the late Eocence archaeocete whale Basilosaurus isis (Birket Qarun Formation, Egypt) fed upon juveniles of the contemporary basilosaurid Dorudon atrox. Finite element analysis (FEA) of a nearly complete adult cranium of B. isis enables estimates of its bite force and tests the animal's capabilities for crushing bone. Two loadcases reflect different biting scenarios: 1) an intitial closing phase, with all adductors active and a full condylar reaction force; and 2) a shearing phase, with the posterior temporalis active and minimized condylar force. The latter is considered probable when the jaws were nearly closed because the preserved jaws do not articulate as the molariform teeth come into occulusion. Reaction forces with all muscles active indicate that B. isis maintained relatively greater bite force anteriorly than seen in large crocodilians, and exerted a maximum bite force of at least 16,400 N at its upper P3. Under the shearing scenario with minimized condylar forces, tooth reaction forces could exceed 20,000 N despite lower magnitudes of muscle force. These bite forces at the teeth are consistent with bone indentations on Dorudon crania, reatract-and-shear hypotheses of Basilosaurus bite function, and seizure of prey by anterior teeth as proposed for other archaeocetes. The whale's bite forces match those estimated for pliosaurus when skull lengths are equalized, suggesting similar tradeoffs of bite function and hydrodynamics. Reaction forces in B. isis were lower than maxima estimated for large crocodylians and carnivorous dinosaurs. However, comparison of force estimates from FEA and regression data indicate that B. isis exerted the largest bite forces yet estimated for any mammal, and greater force than expected from its skull width. Cephalic feeding biomechanics of Basilosaurus isis are thus consistent with habitual predation. PMID:25714832

  11. Bone-breaking bite force of Basilosaurus isis (Mammalia, Cetacea from the late Eocene of Egypt estimated by finite element analysis.

    Directory of Open Access Journals (Sweden)

    Eric Snively

    Full Text Available Bite marks suggest that the late Eocence archaeocete whale Basilosaurus isis (Birket Qarun Formation, Egypt fed upon juveniles of the contemporary basilosaurid Dorudon atrox. Finite element analysis (FEA of a nearly complete adult cranium of B. isis enables estimates of its bite force and tests the animal's capabilities for crushing bone. Two loadcases reflect different biting scenarios: 1 an intitial closing phase, with all adductors active and a full condylar reaction force; and 2 a shearing phase, with the posterior temporalis active and minimized condylar force. The latter is considered probable when the jaws were nearly closed because the preserved jaws do not articulate as the molariform teeth come into occulusion. Reaction forces with all muscles active indicate that B. isis maintained relatively greater bite force anteriorly than seen in large crocodilians, and exerted a maximum bite force of at least 16,400 N at its upper P3. Under the shearing scenario with minimized condylar forces, tooth reaction forces could exceed 20,000 N despite lower magnitudes of muscle force. These bite forces at the teeth are consistent with bone indentations on Dorudon crania, reatract-and-shear hypotheses of Basilosaurus bite function, and seizure of prey by anterior teeth as proposed for other archaeocetes. The whale's bite forces match those estimated for pliosaurus when skull lengths are equalized, suggesting similar tradeoffs of bite function and hydrodynamics. Reaction forces in B. isis were lower than maxima estimated for large crocodylians and carnivorous dinosaurs. However, comparison of force estimates from FEA and regression data indicate that B. isis exerted the largest bite forces yet estimated for any mammal, and greater force than expected from its skull width. Cephalic feeding biomechanics of Basilosaurus isis are thus consistent with habitual predation.

  12. Lizard Bites

    Science.gov (United States)

    ... and Stings Introduction to Bites and Stings Alligator, Crocodile, and Iguana Bites Animal Bites Bee, Wasp, Hornet, ... and Stings Introduction to Bites and Stings Alligator, Crocodile, and Iguana Bites Animal Bites Bee, Wasp, Hornet, ...

  13. Mechanosensation and maximum bite force in edentulous patients rehabilitated with bimaxillary implant-supported fixed dental prostheses

    OpenAIRE

    Luraschi, Julien; Schimmel, Martin; Bernard, Jean-Pierre; Gallucci, German O; Belser, Urs Christophe; Muller, Frauke

    2012-01-01

    The aim of this study was to compare tactile sensitivity and maximum voluntary bite force (MBF) of edentulous patients with implant-supported fixed dental prostheses (IFDP/IFDPs) to those wearing complete dentures (CG-CC) and fully dentate subjects (CG-DD).

  14. Tooth eruption results from bone remodelling driven by bite forces sensed by soft tissue dental follicles: a finite element analysis.

    Directory of Open Access Journals (Sweden)

    Babak Sarrafpour

    Full Text Available Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true 'eruptive force' is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, 'biological response units' in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner

  15. Tooth eruption results from bone remodelling driven by bite forces sensed by soft tissue dental follicles: a finite element analysis.

    Science.gov (United States)

    Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans

    2013-01-01

    Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true 'eruptive force' is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, 'biological response units' in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of the

  16. Nanonet Force Microscopy for Measuring Cell Forces.

    Science.gov (United States)

    Sheets, Kevin; Wang, Ji; Zhao, Wei; Kapania, Rakesh; Nain, Amrinder S

    2016-07-12

    The influence of physical forces exerted by or felt by cells on cell shape, migration, and cytoskeleton arrangement is now widely acknowledged and hypothesized to occur due to modulation of cellular inside-out forces in response to changes in the external fibrous environment (outside-in). Our previous work using the non-electrospinning Spinneret-based Tunable Engineered Parameters' suspended fibers has revealed that cells are able to sense and respond to changes in fiber curvature and structural stiffness as evidenced by alterations to focal adhesion cluster lengths. Here, we present the development and application of a suspended nanonet platform for measuring C2C12 mouse myoblast forces attached to fibers of three diameters (250, 400, and 800 nm) representing a wide range of structural stiffness (3-50 nN/μm). The nanonet force microscopy platform measures cell adhesion forces in response to symmetric and asymmetric external perturbation in single and cyclic modes. We find that contractility-based, inside-out forces are evenly distributed at the edges of the cell, and that forces are dependent on fiber structural stiffness. Additionally, external perturbation in symmetric and asymmetric modes biases cell-fiber failure location without affecting the outside-in forces of cell-fiber adhesion. We then extend the platform to measure forces of (1) cell-cell junctions, (2) single cells undergoing cyclic perturbation in the presence of drugs, and (3) cancerous single-cells transitioning from a blebbing to a pseudopodial morphology. PMID:27410747

  17. Intraoral conversion of occlusal force to electricity and magnetism by biting of piezoelectric elements.

    Science.gov (United States)

    Kameda, Takashi; Ohkuma, Kazuo; Sano, Natsuki; Ogura, Hideo; Terada, Kazuto

    2012-01-01

    Very weak electrical, magnetic and ultrasound signal stimulations are known to promote the formation, metabolism, restoration and stability of bone and surrounding tissues after treatment and operations. We have therefore investigated the possibility of intraoral generation of electricity and magnetism by occlusal force in an in vitro study. Biting bimorph piezoelectric elements with lead zirconate titanate (PZT) using dental models generated appropriate magnetism for bone formation, i. e. 0.5-0.6 gauss, and lower electric currents and higher voltages, i. e. 2.0-6.0 μA at 10-22 V (appropriate levels are 30 μA and 1.25 V), as observed by a universal testing machine. The electric currents and voltages could be changed using amplifier circuits. These results show that intraoral generation of electricity and magnetism is possible and could provide post-operative stabilization and activation of treated areas of bone and the surrounding tissues directly and/or indirectly by electrical, magnetic and ultrasound stimulation, which could accelerate healing.

  18. Bite force in the extant coelacanth Latimeria: the role of the intracranial joint and the basicranial muscle.

    Science.gov (United States)

    Dutel, Hugo; Herbin, Marc; Clément, Gaël; Herrel, Anthony

    2015-05-01

    The terrestrialization process involved dramatic changes in the cranial anatomy of vertebrates. The braincase, which was initially divided into two portions by the intracranial joint in sarcopterygian fishes, became consolidated into a single unit in tetrapods and lungfishes [1-3]. The coelacanth Latimeria is the only extant vertebrate that retains an intracranial joint, which is associated with a unique paired muscle: the basicranial muscle. The intracranial joint has long been thought to be involved in suction feeding by allowing an extensive elevation of the anterior portion of the skull, followed by its rapid depression driven by the basicranial muscle [4-7]. However, we recently challenged this hypothesis [8, 9], and the role of the basicranial muscle with respect to the intracranial joint thus remains unclear. Using 3D biomechanical modeling, we show here that the basicranial muscle and the intracranial joint are involved in biting force generation. By flexing the anterior portion of the skull at the level of the intracranial joint, the basicranial muscle increases the overall bite force. This likely allows Latimeria to feed on a broad range of preys [10, 11] and coelacanths to colonize a wide range of environments during their evolution [4]. The variation in the morphology of the intracranial joint observed in Devonian lobe-finned fishes would have impacted to various degrees their biting performance and might have permitted feeding specializations despite the stability in their lower jaw morphology [12]. VIDEO ABSTRACT.

  19. Snake bites

    Science.gov (United States)

    Bites - snakes ... Snake bites can be deadly if not treated quickly. Because of their smaller body size, children are ... risk for death or serious complications due to snake bites. The right antivenom can save a person's ...

  20. Masseter muscle thickness, chewing efficiency and bite force in edentulous patients with fixed and removable implant-supported prostheses: a cross-sectional multicenter study

    OpenAIRE

    Muller, Frauke; Hernandez, Marta; Gruetter Faineteau, Linda; Aracil-Kessler, Luis; Weingart, Dieter; Schimmel, Martin

    2012-01-01

    Edentulous patients may be restored with conventional dentures (C/C), implant-supported overdentures (IOD) or implant-supported fixed dental prostheses (IFDP). Null-hypotheses: chewing efficiency, maximum voluntary bite force (MBF) and masseter muscle thickness (MMT) are lower in patients with C/IOD compared with the patients with bimaxillary IFDPs. Both groups perform better than C/C and are inferior to fully dentate controls.

  1. Interfacial forces between silica surfaces measured by atomic force microscopy

    Institute of Scientific and Technical Information of China (English)

    DUAN Jinming

    2009-01-01

    Colloidal particle stability and some other interfacial phenomena are governed by interfacial force interactions. The two well known forces are van der Waals force and electrostatic force, as documented by the classical Derjaguin, Landau, Verwey and Overbeek (DLVO) theory. Moreover, advances in modern instrumentation and colloid science suggested that some short-ranged forces or structure forces are important for relevant colloidal systems. The interfacial and/or molecular forces can be measured as a resultant force as function of separation distance by atomic force microscopy (AFM) colloid probe. This article presents a discussion on AFM colloid probe measurement of silica particle and silica wafer surfaces in solutions with some technical notifications in measurement and data convolution mechanisms. The measured forces are then analyzed and discussed based on the 'constant charge' and 'constant potential' models of DLVO theory. The difference between the prediction of DLVO theory and the measured results indicates that there is a strong short-range structure force between the two hydrophilic surfaces, even at extremely low ionic concentration, such as Milli-Q water purity solution.

  2. Recombinant Salivary Proteins of Phlebotomus orientalis are Suitable Antigens to Measure Exposure of Domestic Animals to Sand Fly Bites

    OpenAIRE

    Michal Sima; Blanka Ferencova; Alon Warburg; Iva Rohousova; Petr Volf

    2016-01-01

    Background Certain salivary proteins of phlebotomine sand flies injected into the host skin during blood-feeding are highly antigenic and elicit strong antibody-mediated immune responses in repeatedly-exposed hosts. These antibodies can be measured by enzyme-linked immuno sorbent assays (ELISAs) using salivary gland homogenates (SGHs) as the source of antigens and serve as a markers for exposure to biting sand flies. Large-scale screening for anti-sand fly saliva antibodies requires replaceme...

  3. Measuring Forces between Oxide Surfaces Using the Atomic Force Microscope

    DEFF Research Database (Denmark)

    Pedersen, Henrik Guldberg; Høj, Jakob Weiland

    1996-01-01

    The interactions between colloidal particles play a major role in processing of ceramics, especially in casting processes. With the Atomic Force Microscope (AFM) it is possible to measure the inter-action force between a small oxide particle (a few micron) and a surface as function of surface...

  4. Dynamic Force Measurement with Strain Gauges

    Science.gov (United States)

    Lee, Bruce E.

    1974-01-01

    Discusses the use of four strain gauges, a Wheatstone bridge, and an oscilloscope to measure forces dynamically. Included is an example of determining the centripetal force of a pendulum in a general physics laboratory. (CC)

  5. Thin film sensors for measuring small forces

    OpenAIRE

    F. Schmaljohann; Hagedorn, D.; LÖffler, F.

    2015-01-01

    Especially in the case of measuring small forces, the use of conventional foil strain gauges is limited. The measurement uncertainty rises by force shunts and is due to the polymer foils used, as they are susceptible to moisture. Strain gauges in thin film technology present a potential solution to overcome these effects because of their direct and atomic contact with the measuring body, omitting an adhesive layer and the polymer foil. For force measurements up to 1 N, a...

  6. Animal Bites

    Science.gov (United States)

    ... and complications from bites Never pet, handle, or feed unknown animals Leave snakes alone Watch your children closely around animals Vaccinate your cats, ferrets, and dogs against rabies Spay or neuter ...

  7. Animal Bites

    Science.gov (United States)

    Wild animals usually avoid people. They might attack, however, if they feel threatened, are sick, or are protecting their ... or territory. Attacks by pets are more common. Animal bites rarely are life-threatening, but if they ...

  8. Tick Bites

    Science.gov (United States)

    ... that go outdoors, you need to beware of ticks. Ticks are small bloodsucking parasites. Many species transmit diseases ... of the diseases you can get from a tick bite are Lyme disease, ehrlichiosis, Rocky Mountain spotted ...

  9. Biomolecular Interactions Measured by Atomic Force Microscopy

    NARCIS (Netherlands)

    Willemsen, Oscar H.; Snel, Margot M.E.; Cambi, Alessandra; Greve, Jan; Grooth, de Bart G.; Figdor, Carl G.

    2000-01-01

    Atomic force microscopy (AFM) is nowadays frequently applied to determine interaction forces between biological molecules. Starting with the detection of the first discrete unbinding forces between ligands and receptors by AFM only several years ago, measurements have become more and more quantitati

  10. Axial force measurement for esophageal function testing

    DEFF Research Database (Denmark)

    Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans;

    2009-01-01

    force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...

  11. Force measurement in a nanomachining instrument

    Science.gov (United States)

    Gao, Wei; Hocken, Robert J.; Patten, John A.; Lovingood, John

    2000-11-01

    Two miniature, high sensitivity force transducers were employed to measure the thrust force along the in-feed direction and the cutting force along the cross-feed direction in a nanomachining instrument. The instrument was developed for conducting fundamental experiments of nanocutting especially on brittle materials. The force transducers of piezoelectric quartz type can measure machining forces ranging from 0.2 mN to 10 N. The submillinewton resolution makes it possible to measure the machining forces in the cutting experiments with depths of cut as small as the nanometer level. The stiffness and resonant frequency of the force transducers are 400 mN/nm and 300 kHz, respectively, which meet the specification of the instrument. A force transducer assembly is designed to provide a mechanism to adjust the preload on the force transducer and to decouple the measurement of forces. The assembly consists of three dual-axis circular flexures and a subframe. The axial stiffness of the flexures is designed to be greater than 6×107 N/m and the lateral stiffness of the flexures is designed to be 1×106 N/m to provide proper decoupling of forces.

  12. Axial force measurement for esophageal function testing

    OpenAIRE

    Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the “golden standard” for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure o...

  13. The influence of gender and bruxism on the human maximum bite force Avaliação da influência do gênero e do bruxismo na força máxima de mordida

    Directory of Open Access Journals (Sweden)

    Patrícia dos Santos Calderon

    2006-12-01

    Full Text Available The objective of this research was to evaluate the influence of gender and bruxism on the maximum bite force. The concordance for the physical examination of bruxism between examiners was also evaluated. One hundred and eighteen individuals, from both genders, bruxists and non-bruxists, with an average age of 24 years, were selected for this purpose. For group establishment, every individual was submitted to a specific physical examination for bruxism (performed by three different examiners. Subjects were then divided into four groups according to gender and the presence of bruxism. The maximum bite force was measured using a gnathodynamometer at the first molar area, three times on each side, performed twice. The two measurements were made with a 10-day interval. The highest value was recorded. The mean maximum bite force was statistically higher for males (587.2 N when compared to females (424.9 N (p0.05. The concordance between examiners for physical examination of bruxism was considered optimal.O objetivo dessa pesquisa foi avaliar a influência do gênero e do bruxismo na força máxima de mordida. A concordância interexaminadores para o exame físico de bruxismo também foi avaliada. Cento e dezoito voluntários, com idade média de 24 anos, divididos por gênero e pela presença de bruxismo, foram selecionados. Para o estabelecimento da amostra todos os voluntários foram submetidos a um exame físico específico para bruxismo (realizado por três examinadores. Então, os voluntários foram divididos em quarto grupos de acordo com o gênero e a presença de bruxismo. A força máxima de mordida foi mensurada, com o auxílio de um gnatodinamômetro, na região de primeiro molar, três vezes de cada lado, em duas sessões distintas. As sessões foram separadas por um intervalo de 10 dias. O maior valor dentre os doze obtidos, foi utilizado como sendo a força máxima. A força máxima de mordida foi estatisticamente maior para o g

  14. Ambulatory Measurement of Ground Reaction Forces

    NARCIS (Netherlands)

    Veltink, Peter H.; Liedtke, Christian; Droog, Ed

    2004-01-01

    The measurement of ground reaction forces is important in the biomechanical analysis of gait and other motor activities. It is the purpose of this study to show the feasibility of ambulatory measurement of ground reaction forces using two six degrees of freedom sensors mounted under the shoe. One se

  15. [Snake bites].

    Science.gov (United States)

    Vincent, J L; Créteur, J

    1995-11-01

    Snake bites are a rare occurrence in Belgium. Nevertheless, all doctors should know how to react to this potentially very dangerous emergency. A snakebite does not necessarily result in poisoning: the effects can range from a little local discomfort to a severe systemic reaction with multiple organ failure. Therefore, all snake bites must be treated as serious and should receive adequate treatment. At the same time, hysterical over reaction must be avoided for this risks complications. This article reviews the principal elements of snake bite treatment: from the emergency stage through to stabilization in the hospital. Key points raised are the necessity to immobilize the affected region, to establish adequate perfusion and to anticipate infectious complications. Serum therapy indications are reviewed together with adjuvant interventions such as corticotherapy and heparin therapy. PMID:7501910

  16. Axial force measurement for esophageal function testing

    Institute of Scientific and Technical Information of China (English)

    Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  17. Axial force measurement for esophageal function testing.

    Science.gov (United States)

    Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

    2009-01-14

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method. PMID:19132762

  18. Expression of TypeⅠCollagen mRNA in Rat Molar Periodontal Ligament Under Normal Bite Force%正常力大鼠磨牙牙周膜Ⅰ型胶原mRNA的表达

    Institute of Scientific and Technical Information of China (English)

    刘飞; 赵云凤; 王华蓉; 李甘地

    2001-01-01

    Objective:The main component of the periodontal ligament(PDL) is collagen fiber, especially typeⅠcollagen, and collagen plays an important role in PDL. The aim of this study is to observe the expression of rat PDL mRNA under normal bite force and to investigate the molecular mechanisms of these changes in type Ⅰ collagen mRNA.Methods: 40 male Wistar rats were used, and animals were intra_cardiac perfused with a solution of 4% polyformaldehyde under anesthesia. Dissected mandibles were immersed in the same fixation for 6 hours and subsequently decalcified in EDTA. The demineralized specimens were embedded in paraffin and cut into slices with thickness 5 μm. The probe was synthesized and labeled with digoxigenin. Expression of typeⅠcollagen mRNA was measured by using in situ hybridization(ISH).Results: Under the normal bite force , the mRNA expression of typeⅠ collagen was very strong on the whole, including the alveolar bone side, the root side and the area between them. Positive signals were located mainly in the cytoplasm and some in the nuclei. But the mRNA expression of typeⅠ collagen still had spatial characteristics. The signals in some fibroblasts were apparently stronger than those in other fibroblasts in the apical 1/3 fragment of the roots. The signal of typeⅠ collagen mRNA was strong near the root sides. The expression signal on the proximal alveolar walls was strong,however, on the distal alveolar wall, there was no expression.Conclusion: The expression of typeⅠcollagen mRNA is closely related with bite force.%目的:初探正常咬合力下大鼠牙周膜Ⅰ型胶原在分子水平的改建情况。方法:选用雄性Wistar大鼠,采用地高辛标记寡核苷酸探针原位杂交法,检测大鼠牙周膜Ⅰ型胶原mRNA的表达情况。结果:大鼠磨牙牙周膜有很强的Ⅰ型胶原信号,分布基本均匀,但仍具有一定的空间特异性:近中侧牙槽骨骨壁上有较多致密信号,而远中侧无信号。结论:

  19. Casimir force measurements from silicon carbide surfaces

    NARCIS (Netherlands)

    Sedighi, M.; Svetovoy, V. B.; Palasantzas, G.

    2016-01-01

    Using an atomic force microscope we performed measurements of the Casimir force between a gold-coated (Au) microsphere and doped silicon carbide (SiC) samples. The last of these is a promising material for devices operating under severe environments. The roughness of the interacting surfaces was mea

  20. Human bites - self-care

    Science.gov (United States)

    Bites - human - self-care ... Human bites can occur in two ways: If someone bites you If your hand comes into contact ... bite to express anger or other negative feelings. Human bites may be more dangerous than animal bites. ...

  1. Correlation Force Spectroscopy for Single Molecule Measurements

    OpenAIRE

    Radiom, Milad

    2014-01-01

    This thesis addresses development of a new force spectroscopy tool, correlation force spectroscopy (CFS), for the measurement of the mechanical properties of very small volumes of material (molecular to �[BULLET]m3) at kHz-MHz time-scales. CFS is based on atomic force microscopy (AFM) and the principles of CFS resemble those of dual-trap optical tweezers. CFS consists of two closely-spaced micro-cantilevers that undergo thermal fluctuations. Measurement of the correlation in thermal fluctu...

  2. Measurement of tool forces in diamond turning

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, J.; Dow, T.A.

    1988-12-01

    A dynamometer has been designed and built to measure forces in diamond turning. The design includes a 3-component, piezoelectric transducer. Initial experiments with this dynamometer system included verification of its predicted dynamic characteristics as well as a detailed study of cutting parameters. Many cutting experiments have been conducted on OFHC Copper and 6061-T6 Aluminum. Tests have involved investigation of velocity effects, and the effects of depth and feedrate on tool forces. Velocity has been determined to have negligible effects between 4 and 21 m/s. Forces generally increase with increasing depth of cut. Increasing feedrate does not necessarily lead to higher forces. Results suggest that a simple model may not be sufficient to describe the forces produced in the diamond turning process.

  3. Casimir force measurements from silicon carbide surfaces

    Science.gov (United States)

    Sedighi, M.; Svetovoy, V. B.; Palasantzas, G.

    2016-02-01

    Using an atomic force microscope we performed measurements of the Casimir force between a gold- coated (Au) microsphere and doped silicon carbide (SiC) samples. The last of these is a promising material for devices operating under severe environments. The roughness of the interacting surfaces was measured to obtain information for the minimum separation distance upon contact. Ellipsometry data for both systems were used to extract optical properties needed for the calculation of the Casimir force via the Lifshitz theory and for comparison to the experiment. Special attention is devoted to the separation of the electrostatic contribution to the measured total force. Our measurements demonstrate large contact potential V0(≈0.67 V ) , and a relatively small density of charges trapped in SiC. Knowledge of both Casimir and electrostatic forces between interacting materials is not only important from the fundamental point of view, but also for device applications involving actuating components at separations of less than 200 nm where surface forces play dominant role.

  4. Insect Bites and Stings

    Science.gov (United States)

    Most insect bites are harmless, though they sometimes cause discomfort. Bee, wasp, and hornet stings and fire ant bites usually hurt. Mosquito and flea bites usually itch. Insects can also spread diseases. In the United States, ...

  5. Dog Bite Emergencies

    Science.gov (United States)

    ... Emergency Care Animal Welfare Veterinary Careers Public Health Dog bite emergencies What do I do if I’ ... vaccination records. What do I do if my dog bites someone? Dog bites are scary for everyone ...

  6. Reality Bites

    OpenAIRE

    Jul, David; Høst, Asger Kring; Licht, Esben Hendriksen; Rasmussen, Mette Løth; Petersen, Nikolaj Porn Sloth; Westergaard, Anna; Oustrup, Mads Damkjær

    2012-01-01

    Nærværende rapport omhandler designet af endagskonferencen Reality Bites, som blev afholdt på Roskilde Universitet torsdag den 10. maj 2012. Formålene med konferencen var at inspirere og provokere deltageren (målgruppen værende universitetsstuderende på 2. til 6. Semester), til at reflektere over egne evner, mål og muligheder og således motivere den studerende til, aktivt at bruge sin studietid som ramme til at udvikle og forme sig selv. Primært med udgangspunkt i Victor Turner og Richard Sch...

  7. Knitting Force Measurement on Flat Knitting Machines

    Directory of Open Access Journals (Sweden)

    A. Fouda

    2014-01-01

    Full Text Available Knittability can be defined as the ability of yarns to run on knitting machines without problems. Knittability can be achieved when less stress is applied on the knitting machine parts by the knitting yarns. This paper presents a novel measuring system for the knitting force needed to perform knitting yarns on flat knitting machine based on data acquisition system (DAS. The proposed system is used to measure the knitting force at different machine settings and different properties of the knitting yarns to determine the optimal production conditions. For this reason, three types of knitted fabric structures (single jersey, Rib 1 × 1, and full cardigan with three different loop lengths and five different twists of ply yarn were produced. The obtained results showed the optimal yarn ply twist factor (αe which gave minimum knitting force (less stress on needles or knitting yarns at different loop lengths for each structure.

  8. A MEMS sensor for microscale force measurements

    Science.gov (United States)

    Majcherek, S.; Aman, A.; Fochtmann, J.

    2016-02-01

    This paper describes the development and testing of a new MEMS-based sensor device for microscale contact force measurements. A special MEMS cell was developed to reach higher lateral resolution than common steel-based load cells with foil-type strain gauges as mechanical-electrical converters. The design provided more than one normal force measurement point with spatial resolution in submillimeter range. Specific geometric adaption of the MEMS-device allowed adjustability of its measurement range between 0.5 and 5 N. The thin film nickel-chromium piezo resistors were used to achieve a mechanical-electrical conversion. The production process was realized by established silicon processing technologies such as deep reactive ion etching and vapor deposition (sputtering). The sensor was tested in two steps. Firstly, the sensor characteristics were carried out by application of defined loads at the measurement points by a push-pull tester. As a result, the sensor showed linear behavior. A measurement system analysis (MSA1) was performed to define the reliability of the measurement system. The measured force values had the maximal relative deviation of 1% to average value of 1.97 N. Secondly, the sensor was tested under near-industrial conditions. In this context, the thermal induced relaxation behavior of the electrical connector contact springs was investigated. The handling of emerging problems during the characterization process of the sensor is also described.

  9. A MEMS sensor for microscale force measurements

    International Nuclear Information System (INIS)

    This paper describes the development and testing of a new MEMS-based sensor device for microscale contact force measurements. A special MEMS cell was developed to reach higher lateral resolution than common steel-based load cells with foil-type strain gauges as mechanical-electrical converters. The design provided more than one normal force measurement point with spatial resolution in submillimeter range. Specific geometric adaption of the MEMS-device allowed adjustability of its measurement range between 0.5 and 5 N. The thin film nickel-chromium piezo resistors were used to achieve a mechanical-electrical conversion. The production process was realized by established silicon processing technologies such as deep reactive ion etching and vapor deposition (sputtering). The sensor was tested in two steps. Firstly, the sensor characteristics were carried out by application of defined loads at the measurement points by a push-pull tester. As a result, the sensor showed linear behavior. A measurement system analysis (MSA1) was performed to define the reliability of the measurement system. The measured force values had the maximal relative deviation of 1% to average value of 1.97 N. Secondly, the sensor was tested under near-industrial conditions. In this context, the thermal induced relaxation behavior of the electrical connector contact springs was investigated. The handling of emerging problems during the characterization process of the sensor is also described. (paper)

  10. Simplified fundamental force and mass measurements

    Science.gov (United States)

    Robinson, I. A.

    2016-08-01

    The watt balance relates force or mass to the Planck constant h, the metre and the second. It enables the forthcoming redefinition of the unit of mass within the SI by measuring the Planck constant in terms of mass, length and time with an uncertainty of better than 2 parts in 108. To achieve this, existing watt balances require complex and time-consuming alignment adjustments limiting their use to a few national metrology laboratories. This paper describes a simplified construction and operating principle for a watt balance which eliminates the need for the majority of these adjustments and is readily scalable using either electromagnetic or electrostatic actuators. It is hoped that this will encourage the more widespread use of the technique for a wide range of measurements of force or mass. For example: thrust measurements for space applications which would require only measurements of electrical quantities and velocity/displacement.

  11. Calibration of lateral force measurements in atomic force microscopy with a piezoresistive force sensor

    International Nuclear Information System (INIS)

    We present here a method to calibrate the lateral force in the atomic force microscope. This method makes use of an accurately calibrated force sensor composed of a tipless piezoresistive cantilever and corresponding signal amplifying and processing electronics. Two ways of force loading with different loading points were compared by scanning the top and side edges of the piezoresistive cantilever. Conversion factors between the lateral force and photodiode signal using three types of atomic force microscope cantilevers with rectangular geometries (normal spring constants from 0.092 to 1.24 N/m and lateral stiffness from 10.34 to 101.06 N/m) were measured in experiments using the proposed method. When used properly, this method calibrates the conversion factors that are accurate to ±12.4% or better. This standard has less error than the commonly used method based on the cantilever's beam mechanics. Methods such of this allow accurate and direct conversion between lateral forces and photodiode signals without any knowledge of the cantilevers and the laser measuring system

  12. Tail biting and feather pecking

    OpenAIRE

    Brunberg, Emma

    2011-01-01

    It is well known that abnormal animal behaviour is affected by both environment and genetics. This thesis aimed to use behavioural observations as well as gene expression measurements to explore how animals that perform and receive tail biting (pigs) and feather pecking (laying hens) differ from individuals that are not involved in these behaviours. In study I, the results suggested that tail biting is related to other abnormal behaviours. Pigs performing a high frequency of tail bi...

  13. Dynamics of gecko locomotion: a force-measuring array to measure 3D reaction forces.

    Science.gov (United States)

    Dai, Zhendong; Wang, Zhouyi; Ji, Aihong

    2011-03-01

    Measuring the interaction between each foot of an animal and the substrate is one of the most effective ways to understand the dynamics of legged locomotion. Here, a new facility - the force-measuring array (FMA) - was developed and applied to measure 3D reaction forces of geckos on different slope surfaces. The FMA consists of 16 3D sensors with resolution to the mN level. At the same time the locomotion behaviour of geckos freely moving on the FMA was recorded by high speed camera. The reaction forces acting on the gecko's individual feet measured by the FMA and correlated with locomotion behaviour provided enough information to reveal the mechanical and dynamic secrets of gecko locomotion. Moreover, dynamic forces were also measured by a force platform and correlated with locomotion behaviour. The difference between the forces measured by the two methods is discussed. From the results we conclude that FMA is the best way to obtain true reaction forces acting on the gecko's individual feet.

  14. Cat and Dog Bites

    Science.gov (United States)

    MENU Return to Web version Cat and Dog Bites Cat and Dog Bites How should I take care of a bite from a cat or a dog? Whether from a family pet or a neighborhood stray, cat and dog bites are common. Here are some things you ...

  15. Spider Bites (For Parents)

    Science.gov (United States)

    ... brown recluse spider bite: red blister in the center with surrounding bluish discoloration around the bite swelling or redness around the bite development of pain around the bite within 2 to 8 hours joint stiffness or pain nausea, vomiting body rash fever and ...

  16. Measurement adhesion force between fine particle and effect of humidity: An study with Atomic Force Microscopy

    International Nuclear Information System (INIS)

    Adhesion force is interaction between particle- particle and particle surface. First Hertz in 1882 calculated adhesion force between spherical particle and planar surface. Adhesion force in interested for scientist and different industries such as paint, foot, pharmaceutical, etc. In this study we measured adhesion force between fine particle such as silica and silicon and mica surface, with Atomic Force Microscopy. The adhesion force measured between particle-planar surfaces with Atomic Force Microscopy on different humidity and simulated results.

  17. Injurious tail biting in pigs

    DEFF Research Database (Denmark)

    D'Eath, R.B.; Amott, G.; Turner, S. P.;

    2014-01-01

    risk, it is important to detect and treat tail biting as soon as it occurs. Early warning signs before the first bloody tails appear, such as pigs holding their tails tucked under, could in future be automatically detected using precision livestock farming methods enabling earlier reaction......Tail biting is a serious animal welfare and economic problem in pig production. Tail docking, which reduces but does not eliminate tail biting, remains widespread. However, in the EU tail docking may not be used routinely, and some ‘alternative’ forms of pig production and certain countries do...... not allow tail docking at all. Against this background, using a novel approach focusing on research where tail injuries were quantified, we review the measures that can be used to control tail biting in pigs without tail docking. Using this strict criterion, there was good evidence that manipulable...

  18. Force measurement of low forces in combination with high dead loads by the use of electromagnetic force compensation

    Science.gov (United States)

    Diethold, Christian; Hilbrunner, Falko

    2012-07-01

    This paper discusses the force measurement of small forces in combination with high dead loads. The measurement force acts perpendicular to gravity, while the dead load is orientated in the direction of gravity. Furthermore, the influence of the dead load on the metrological properties is described. The application is the flow rate measurement of conducting fluids by Lorentz force (Thess et al 2006 Phys. Rev. Lett. 96 164501). The aim is to measure forces with a resolution of FM = 10-6 N. The dead load is mainly due to the mass of the magnet system. It is of the order of magnitude of FG = 10 N. The force measurement system works with the principle of electromagnetic force compensation. The applied force is compensated by a Lorentz force induced by a current in a voice coil and a magnetic field of a permanent magnet. The current is proportional to the applied force.

  19. Force measurement of low forces in combination with high dead loads by the use of electromagnetic force compensation

    International Nuclear Information System (INIS)

    This paper discusses the force measurement of small forces in combination with high dead loads. The measurement force acts perpendicular to gravity, while the dead load is orientated in the direction of gravity. Furthermore, the influence of the dead load on the metrological properties is described. The application is the flow rate measurement of conducting fluids by Lorentz force (Thess et al 2006 Phys. Rev. Lett. 96 164501). The aim is to measure forces with a resolution of FM = 10−6 N. The dead load is mainly due to the mass of the magnet system. It is of the order of magnitude of FG = 10 N. The force measurement system works with the principle of electromagnetic force compensation. The applied force is compensated by a Lorentz force induced by a current in a voice coil and a magnetic field of a permanent magnet. The current is proportional to the applied force. (paper)

  20. Is extreme bite performance associated with extreme morphologies in sharks?

    Science.gov (United States)

    Huber, Daniel R; Claes, Julien M; Mallefet, Jérôme; Herrel, Anthony

    2009-01-01

    As top predators in many oceanic communities, sharks are known to eat large prey and are supposedly able to generate high bite forces. This notion has, however, largely gone untested due to the experimental intractability of these animals. For those species that have been investigated, it remains unclear whether their high bite forces are simply a consequence of their large body size or the result of diet-related adaptation. As aquatic poikilotherms, sharks can grow very large, making them ideal subjects with which to investigate the effects of body size on bite force. Relative bite-force capacity is often associated with changes in head shape because taller or wider heads can, for example, accommodate larger jaw muscles. Constraints on bite force in general may also be released by changes in tooth shape. For example, more pointed teeth may allow a predator to penetrate prey more effectively than blunt, pavementlike teeth. Our analyses show that large sharks do not bite hard for their body size, but they generally have larger heads. Head width is the best predictor of bite force across the species included in our study as indicated by a multiple regression model. Contrary to our predictions, sharks with relatively high bite forces for their body size also have relatively more pointed teeth at the front of the tooth row. Moreover, species including hard prey in their diet are characterized by high bite forces and narrow and pointed teeth at the jaw symphysis. PMID:19006469

  1. Is extreme bite performance associated with extreme morphologies in sharks?

    Science.gov (United States)

    Huber, Daniel R; Claes, Julien M; Mallefet, Jérôme; Herrel, Anthony

    2009-01-01

    As top predators in many oceanic communities, sharks are known to eat large prey and are supposedly able to generate high bite forces. This notion has, however, largely gone untested due to the experimental intractability of these animals. For those species that have been investigated, it remains unclear whether their high bite forces are simply a consequence of their large body size or the result of diet-related adaptation. As aquatic poikilotherms, sharks can grow very large, making them ideal subjects with which to investigate the effects of body size on bite force. Relative bite-force capacity is often associated with changes in head shape because taller or wider heads can, for example, accommodate larger jaw muscles. Constraints on bite force in general may also be released by changes in tooth shape. For example, more pointed teeth may allow a predator to penetrate prey more effectively than blunt, pavementlike teeth. Our analyses show that large sharks do not bite hard for their body size, but they generally have larger heads. Head width is the best predictor of bite force across the species included in our study as indicated by a multiple regression model. Contrary to our predictions, sharks with relatively high bite forces for their body size also have relatively more pointed teeth at the front of the tooth row. Moreover, species including hard prey in their diet are characterized by high bite forces and narrow and pointed teeth at the jaw symphysis.

  2. Atomic force microscopy and direct surface force measurements

    NARCIS (Netherlands)

    Ralston, J.; Larson, I.; Rutland, M.; Feiler, A.; Kleijn, J.M.

    2005-01-01

    The atomic force microscope (AFM) is designed to provide high-resolution (in the ideal case, atomic) topographical analysis, applicable to both conducting and nonconducting surfaces. The basic imaging principle is very simple: a sample attached to a piezoelectric positioner is rastered beneath a sha

  3. Tail-biting: a new perspective.

    Science.gov (United States)

    Taylor, Nina R; Main, David C J; Mendl, Mike; Edwards, Sandra A

    2010-11-01

    Tail-biting data from different studies are difficult to compare because a range of definitions of tail-biting behaviour and tail-biting lesions are used. Although records from abattoirs provide a large database, their usefulness is restricted as tail-biting is under-recorded and environmental and husbandry factors associated with the behaviour are unlikely to be known. Both farm and abattoir data provide no information on the number of pigs biting, only those bitten. Studying individual animals that tail-bite should give a better understanding of the pig's motivation to tail-bite and which of the components of its environment should be adjusted to improve welfare. This review examines the existing literature on tail-biting in pigs but considered from a new perspective using three different descriptive behavioural types, namely, 'two-stage', 'sudden-forceful' and 'obsessive', each of which may have different motivational bases. The article also considers the different environmental and husbandry factors which may affect each type of behaviour and discusses why this is such a complicated field and why it is often difficult to draw conclusions from available research. PMID:19804997

  4. Fighting and Biting

    Science.gov (United States)

    ... excessive or harsh discipline or exposure to physical violence. Parents should remember that children who are teething might also bite. Biting is the most common reason children get expelled from day care. What to ...

  5. Tick Bites (For Parents)

    Science.gov (United States)

    ... Things to Know About Zika & Pregnancy First Aid: Tick Bites KidsHealth > For Parents > First Aid: Tick Bites ... find on the skin. Signs and Symptoms Of Tick-Related Diseases: a red bump ringed by an ...

  6. Human bites (image)

    Science.gov (United States)

    Human bites present a high risk of infection. Besides the bacteria which can cause infection, there is ... the wound extends below the skin. Anytime a human bite has broken the skin, seek medical attention.

  7. A Simple Apparatus for Electrostatic Force Measurement.

    Science.gov (United States)

    Hale, D. P.

    1981-01-01

    Describes the construction of an apparatus that demonstrates that electrostatic forces can be large and also gives some idea of dependence of electrostatic forces between charged parallel discs on potential differences and separation. (CS)

  8. Impact velocities of the teeth after a sudden unloading at various initial bite forces, degrees of mouth opening, and distances of travel

    NARCIS (Netherlands)

    Nagashima, T; Slager, GEC; Broekhuijsen, ML; vanWilligen, JD

    1997-01-01

    A potentially dangerous situation arises when an individual bites on hard and brittle food which suddenly breaks, since the impact velocity of the lower teeth onto the upper teeth after the food is broken can be high and may cause dental damage. The present experiments were designed to study the mag

  9. Measurements for the rotordynamic shroud forces for centrifugal pumps

    OpenAIRE

    Guinzburg, A.; Brennen, C. E.; Acosta, A.J; Caughey, T. K.

    1990-01-01

    An experiment was designed to measure the rotordynamic shroud forces on a centrigual pump impeller. The measurements were doen for various whirl/impeller ratios and for different flow rates. A destabilising tangential force was measured for small positive whirl ratios and this force decreased with increasing flow rate.

  10. Measurements of the rotordynamic shroud forces for centrifugal pumps

    Science.gov (United States)

    Guinzburg, A.; Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1990-01-01

    An experiment was designed to measure the rotordynamic shroud forces on a centrifugal pump impeller. The measurements were done for various whirl/impeller speed ratios and for different flow rates. A destabilizing tangential force was measured for small positive whirl ratios and this force decreased with increasing flow rate.

  11. Recombinant Salivary Proteins of Phlebotomus orientalis are Suitable Antigens to Measure Exposure of Domestic Animals to Sand Fly Bites.

    Directory of Open Access Journals (Sweden)

    Michal Sima

    2016-03-01

    Full Text Available Certain salivary proteins of phlebotomine sand flies injected into the host skin during blood-feeding are highly antigenic and elicit strong antibody-mediated immune responses in repeatedly-exposed hosts. These antibodies can be measured by enzyme-linked immuno sorbent assays (ELISAs using salivary gland homogenates (SGHs as the source of antigens and serve as a markers for exposure to biting sand flies. Large-scale screening for anti-sand fly saliva antibodies requires replacement of SGH with recombinant salivary proteins. In East Africa, Phlebotomus orientalis is the main vector of Leishmania donovani, a trypanosomatid parasite causing visceral leishmaniasis. We tested recombinant salivary proteins derived from Ph. orientalis saliva to study exposure of domestic animals to this sand fly species.Antigenic salivary proteins from Ph. orientalis were identified by immunoblot and mass spectrometry. Recombinant apyrase rPorSP15, yellow-related protein rPorSP24, ParSP25-like protein rPorSP65, D7-related protein rPorSP67, and antigen 5-related protein rPorSP76 were tested using ELISA with sera of domestic animals from L. donovani foci in Ethiopia where Ph. orientalis is present. Our results highlighted recombinant yellow-related protein rPorSP24 as the most promising antigen, displaying a high positive correlation coefficient as well as good sensitivity and specificity when compared to SGH. This recombinant protein was the most suitable one for testing sera of dogs, sheep, and goats. In addition, a different antigen, rPorSP65 was found efficacious for testing canine sera.Recombinant salivary proteins of Ph. orientalis, specifically rPorSP24, were shown to successfully substitute SGH in serological experiments to measure exposure of domestic animals to Ph. orientalis, the vector of L. donovani. The results suggest that rPorSP24 might be a suitable antigen for detecting anti-Ph. orientalis antibody-mediated reactions also in other host species.

  12. Correlation study of the relationship between gravity center movement and bite force during the mixed dentition period%混合牙列期身体重心动摇和咬合力的相关性研究

    Institute of Scientific and Technical Information of China (English)

    杜小沛; 纪莹; 陆海涛; 张婷婷; 邱伟

    2016-01-01

    目的:调查混合牙列期身体重心动摇与咬合力之间的关系。方法56名处于Hellman咬合发育Ⅲ期A阶段的健康小学生纳入研究。通过检查咬合平衡中点与中线的距离( X)关系,X≤5 mm被划分为正中组,X>5 mm被划分为偏移组。使用自动姿态分析系统测定了身体平衡相关开闭眼时的重心动摇距离、重心动摇面积。使用牙齿压力感应装置Dental Prescale®测定了咬合接触面积、平均咬合力、最大咬合压力,咬合力和咬合平衡。结果咬合接触面积和咬合力的测试结果男女分别为18.1 mm2、712.2 N和14.1 mm2、541.8 N,差异均具有统计学意义(P<0.05)。咬合平衡中点正中组与偏移组的咬合接触面积、咬合力之间差异具有统计学意义(P <0.05)。咬合平衡中点正中组开、闭眼时期的重心动摇距离、面积明显小于偏移组,咬合平衡与开、闭眼时期的重心动摇距离、面积有关且具有统计学意义(P<0.05)。重心动摇稳定组的咬合接触面积大于动摇组,两者差异具有统计学意义(P<0.05)。结论 Hellman咬合发育Ⅲ期A阶段儿童咬合平衡和人体重心动摇存在相关性,咬合接触面积与身体重心动摇相互影响。%Objective To investigate the relationship between gravity center movement and bite force during the mixed dentition period. Methods Fifty-six healthy children with Hellman's Dental AgeⅢ A were selected from an ele-mentary school. The body balance, distance and area of gravity center movement ( GCM) were measured with automatic posture analytical devices. Occlusal abilities were measured with pressure-sensitive sheets ( Dental Prescale® ) , including occlusal contacts area, average occlusal pressure, maximum occlusal pressure, occlusal force and occlusal balance. Re-sults The occlusal contact area and bite force test results of male and female group were 18. 1 mm2 , 712. 2 N and 14. 1 mm2, 541. 8 N, The differences were statistically

  13. Cantilevers orthodontics forces measured by fiber sensors

    Science.gov (United States)

    Schneider, Neblyssa; Milczewski, Maura S.; de Oliveira, Valmir; Guariza Filho, Odilon; Lopes, Stephani C. P. S.; Kalinowski, Hypolito J.

    2015-09-01

    Fibers Bragg Gratings were used to evaluate the transmission of the forces generates by orthodontic mechanic based one and two cantilevers used to move molars to the upright position. The results showed levels forces of approximately 0,14N near to the root of the molar with one and two cantilevers.

  14. Rigid two-axis MEMS force plate for measuring cellular traction force

    Science.gov (United States)

    Takahashi, Hidetoshi; Jung, Uijin G.; Kan, Tetsuo; Tsukagoshi, Takuya; Matsumoto, Kiyoshi; Shimoyama, Isao

    2016-10-01

    Cellular traction force is one of the important factors for understanding cell behaviors, such as spreading, migration and differentiation. Cells are known to change their behavior according to the mechanical stiffness of the environment. However, the measurement of cell traction forces on a rigid environment has remained difficult. This paper reports a micro-electromechanical systems (MEMS) force plate that provides a cellular traction force measurement on a rigid substrate. Both the high force sensitivity and high stiffness of the substrate were obtained using piezoresistive sensing elements. The proposed force plate consists of a 70 µm  ×  15 µm  ×  5 µm base as the substrate for cultivating a bovine aortic smooth muscle cell, and the supporting beams with piezoresistors on the sidewall and the surface were used to measure the forces in both the horizontal and vertical directions. The spring constant and force resolution of the fabricated force plate in the horizontal direction were 0.2 N m-1 and less than 0.05 µN, respectively. The cell traction force was measured, and the traction force increased by approximately 1 µN over 30 min. These results demonstrate that the proposed force plate is applicable as an effective traction force measurement.

  15. Capillary-force measurement on SiC surfaces

    NARCIS (Netherlands)

    Sedighi, M.; Svetovoy, V. B.; Palasantzas, G.

    2016-01-01

    Capillary forces have been measured by atomic force microscopy in the sphere-plate geometry, in a controlled humidity environment, between smooth silicon carbide and borosilicate glass spheres. The force measurements were performed as a function of the rms surface roughness similar to 4-14 nm mainly

  16. MEASUREMENT OF ADHESION FORCES IN AIR WITH THE VIBRATION METHOD

    Institute of Scientific and Technical Information of China (English)

    Siegfried; Ripperger; Konrad; Hein

    2005-01-01

    The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally altemating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. For the calculation of the adhesion forces, an approach by Rabinovich was combined with approximations of plastic micro asperity flattening. The Rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces. rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas.

  17. Animal bites - self-care

    Science.gov (United States)

    Bites - animals - self-care ... Most animal bites come from pets. Dog bites are common and most often happen to children. Cat bites are ... which can cause deeper puncture wounds. Most other animal bites are caused by stray or wild animals, ...

  18. Tail biting in pigs.

    Science.gov (United States)

    Schrøder-Petersen, D L; Simonsen, H B

    2001-11-01

    One of the costly and welfare-reducing problems in modern pig production is tail biting. Tail biting is an abnormal behaviour, characterized by one pig's dental manipulation of another pig's tail. Tail biting can be classified into two groups: the pre-injury stage, before any wound on the tail is present, and the injury stage, where the tail is wounded and bleeding. Tail biting in the injury stage will reduce welfare of the bitten pig and the possible spread of infection is a health as well as welfare problem. The pigs that become tail biters may also suffer, because they are frustrated due to living in a stressful environment. This frustration may result in an excessive motivation for biting the tails of pen mates. This review aims to summarize recent research and theories in relation to tail biting. PMID:11681870

  19. Theoretical Models for Surface Forces and Adhesion and Their Measurement Using Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Osvaldo N. Oliveira

    2012-10-01

    Full Text Available The increasing importance of studies on soft matter and their impact on new technologies, including those associated with nanotechnology, has brought intermolecular and surface forces to the forefront of physics and materials science, for these are the prevailing forces in micro and nanosystems. With experimental methods such as the atomic force spectroscopy (AFS, it is now possible to measure these forces accurately, in addition to providing information on local material properties such as elasticity, hardness and adhesion. This review provides the theoretical and experimental background of afs, adhesion forces, intermolecular interactions and surface forces in air, vacuum and in solution.

  20. In Vivo Measurement of Mesokinesis in Gekko gecko: The Role of Cranial Kinesis during Gape Display, Feeding and Biting.

    Directory of Open Access Journals (Sweden)

    Stéphane J Montuelle

    Full Text Available Cranial kinesis refers to movements of skeletal sub-units relative to one another at mobile sutures within the skull. The presence and functional significance of cranial kinesis has been investigated in various vertebrates, with much of our understanding coming from comparative studies and manipulation of ligamentous specimens. Drawing on these studies, cranial kinesis in lizards has been modeled as a four-bar linkage system involving streptostyly (rotation of the quadrate, hypokinesis (dorsoventral flexion and extension of the palato-maxillary sub-unit, mesokinesis (dorsoventral flexion and extension of the snout at the fronto-parietal suture and metakinesis (sliding movements between parietal and supraocciptal bones. In vivo studies, although limited, suggest that cranial kinesis serves an important role during routine behaviors such as feeding. Here, we use X-ray Reconstruction Of Moving Morphology to further quantify mesokinesis in vivo in Gekko gecko during three routine behaviors: gape display, biting and post-ingestion feeding. During gape display, the snout rotates dorsally above rest position, with mesokinesis accounting for a 10% increase in maximum gape over that achieved solely by the depression of the lower jaw. During defensive biting, the snout rotates ventrally below rest position to participate in gape closure. Finally, ventroflexion of the snout also occurs during post-ingestion feeding, accounting for 42% of gape closure during intra-oral transport, 86% during puncture-crushing, and 61% during pharyngeal packing. Mesokinesis thus appears to facilitate prey puncturing by allowing the snout to rotate ventrally so that the upper teeth pierce the prey item, thus limiting the need for large movements of the lower jaw. This is suggested to maintain a firm grip on the prey and reduce the possibility of prey escape. More generally, this study demonstrates that mesokinesis is a key component of defensive biting and gape display

  1. In Vivo Measurement of Mesokinesis in Gekko gecko: The Role of Cranial Kinesis during Gape Display, Feeding and Biting.

    Science.gov (United States)

    Montuelle, Stéphane J; Williams, Susan H

    2015-01-01

    Cranial kinesis refers to movements of skeletal sub-units relative to one another at mobile sutures within the skull. The presence and functional significance of cranial kinesis has been investigated in various vertebrates, with much of our understanding coming from comparative studies and manipulation of ligamentous specimens. Drawing on these studies, cranial kinesis in lizards has been modeled as a four-bar linkage system involving streptostyly (rotation of the quadrate), hypokinesis (dorsoventral flexion and extension of the palato-maxillary sub-unit), mesokinesis (dorsoventral flexion and extension of the snout at the fronto-parietal suture) and metakinesis (sliding movements between parietal and supraocciptal bones). In vivo studies, although limited, suggest that cranial kinesis serves an important role during routine behaviors such as feeding. Here, we use X-ray Reconstruction Of Moving Morphology to further quantify mesokinesis in vivo in Gekko gecko during three routine behaviors: gape display, biting and post-ingestion feeding. During gape display, the snout rotates dorsally above rest position, with mesokinesis accounting for a 10% increase in maximum gape over that achieved solely by the depression of the lower jaw. During defensive biting, the snout rotates ventrally below rest position to participate in gape closure. Finally, ventroflexion of the snout also occurs during post-ingestion feeding, accounting for 42% of gape closure during intra-oral transport, 86% during puncture-crushing, and 61% during pharyngeal packing. Mesokinesis thus appears to facilitate prey puncturing by allowing the snout to rotate ventrally so that the upper teeth pierce the prey item, thus limiting the need for large movements of the lower jaw. This is suggested to maintain a firm grip on the prey and reduce the possibility of prey escape. More generally, this study demonstrates that mesokinesis is a key component of defensive biting and gape display behaviors, as well as

  2. Quantitative measurement of tip sample forces by dynamic force spectroscopy in ambient conditions

    Science.gov (United States)

    Hölscher, H.; Anczykowski, B.

    2005-03-01

    We introduce a dynamic force spectroscopy technique enabling the quantitative measurement of conservative and dissipative tip-sample forces in ambient conditions. In difference to the commonly detected force-vs-distance curves dynamic force microscopy allows to measure the full range of tip-sample forces without hysteresis effects caused by a jump-to-contact. The approach is based on the specific behavior of a self-driven cantilever (frequency-modulation technique). Experimental applications on different samples (Fischer-sample, silicon wafer) are presented.

  3. Towards a Casimir force measurement between micromachined parallel plate structures

    NARCIS (Netherlands)

    Syed Nawazuddin, M.B.; Lammerink, Theo S.J.; Berenschot, Erwin; Boer, de Meint; Ma, Ke-Chun; Elwenspoek, Miko C.; Wiegerink, Remco J.

    2012-01-01

    Ever since its prediction, experimental investigation of the Casimir force has been of great scientific interest. Many research groups have successfully attempted quantifying the force with different device geometries; however, measurement of the Casimir force between parallel plates with sub-micron

  4. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... care & guidelines Clinical guidelines Appropriate use criteria Patient safety Choosing Wisely Quality measures Outcomes in Dermatology Pilot ... Artificial nails Healthy nails Child nail care Manicure safety Nail biting Younger skin Kids’ zone Video library ...

  5. Measuring Agglomeration Forces in a Financial Center

    OpenAIRE

    Bourgain, Arnaud; Pieretti, Patrice

    2006-01-01

    Basing on Scitovsky's (1954) definition of external economies and applying the method of Caballero and Lyons (1990) to macro data of Luxembourg services industry, we find significant agglomeration forces between financial intermediaries (downstream industry) on the one hand and business services and computer industry (upstream industries) on the other.

  6. Measuring the Forces between Magnetic Dipoles

    Science.gov (United States)

    Gayetsky, Lisa E.; Caylor, Craig L.

    2007-01-01

    We describe a simple undergraduate lab in which students determine how the force between two magnetic dipoles depends on their separation. We consider the case where both dipoles are permanent and the case where one of the dipoles is induced by the field of the other (permanent) dipole. Agreement with theoretically expected results is quite good.

  7. Measurement of Laterally Induced Optical Forces at the Nanoscale

    CERN Document Server

    Huang, Fei; Wickramasinghe, Hemanta Kumar

    2016-01-01

    We demonstrate the measurement of laterally induced optical forces using an Atomic Force Microscope (AFM). The lateral electric field distribution between a gold coated AFM probe and a nano-aperture in a gold film is mapped by measuring the lateral optical force between the apex of the AFM probe and the nano-aperture. Torsional eigenmodes of an AFM cantilever probe were used to detect the laterally induced optical forces. We engineered the cantilever shape using a focused ion beam to enhance the torsional eigenmode resonance. The measured lateral optical force agrees well with simulations. This technique can be extended to simultaneously detect both lateral and longitudinal optical forces at the nanoscale by using an AFM cantilever as a multichannel detector. This will enable simultaneous Photon Induced Force Microscopy (PIFM) detection of molecular responses with different incident field polarizations. The technique can be implemented on both cantilever and tuning fork based AFMs.

  8. Maximal bite force in young adults with temporomandibular disorders and bruxism Força de mordida máxima em adultos jovens com disfunção temporomandibular e bruxismo

    Directory of Open Access Journals (Sweden)

    Raquel Aparecida Pizolato

    2007-09-01

    Full Text Available Parafunctional habits, such as bruxism, are contributory factors for temporomandibular disorders (TMD. The aim of this study was to evaluate the maximal bite force (MBF in the presence of TMD and bruxism (TMDB in young adults. Twelve women (mean age 21.5 years and 7 men (mean age 22.4 years, composed the TMDB group. Ten healthy women and 9 men (mean age 21.4 and 22.4 years, respectively formed the control group. TMD symptoms were evaluated by a structured questionnaire and clinical signs/symptoms were evaluated during clinical examination. A visual analogical scale (VAS was applied for stress assessment. MBF was measured with a gnatodynamometer. The subjects were asked to bite 2 times with maximal effort, during 5 seconds, with a rest interval of about one minute. The highest values were considered. The data were analyzed with Shapiro-Wilks W-test, descriptive statistics, paired or unpaired t tests or Mann-Whitney tests when indicated, and Fisher's exact test (p Hábitos parafuncionais, como o bruxismo, podem contribuir para a disfunção temporomandibular (DTM. O objetivo deste trabalho foi avaliar a força de mordida máxima (FMM na presença de DTM e bruxismo (DTMB em adultos jovens. Doze mulheres (idade média de 21,5 anos e sete homens (idade média 22,4 anos compuseram o grupo DTMB. O grupo controle foi formado por 10 mulheres e 9 homens saudáveis, com idades médias de 21,4 e 22,4 anos, respectivamente. Os sintomas de DTM foram avaliados com um questionário estruturado, e os sinais/sintomas clínicos foram avaliados no exame clínico. Para avaliar estresse, utilizou-se a escala analógica visual (VAS. A FMM foi mensurada com gnatodinamômetro, e o participante foi orientado a morder com o máximo esforço durante 5 segundos, duas vezes, com intervalo de aproximadamente 1 minuto, considerando-se os valores máximos. Os dados foram analisados pelo teste de Shapiro-Wilks, estatística descritiva, teste t pareado e independente, Mann

  9. First Aid: Animal Bites

    Science.gov (United States)

    ... Story" 5 Things to Know About Zika & Pregnancy First Aid: Animal Bites KidsHealth > For Parents > First Aid: Animal Bites Print A A A Text Size ... For Kids For Parents MORE ON THIS TOPIC First Aid & Safety Center Infections That Pets Carry Dealing With ...

  10. Insect bites and stings

    Science.gov (United States)

    ... likely to cause itching than pain. Insect and spider bites cause more deaths from venom reactions than bites from snakes. ... are harmless. If possible, bring the insect or spider that bit you with you when you go for medical treatment so it can be identified.

  11. A Novel Device for Measuring Forces in Endoluminal Procedures

    Directory of Open Access Journals (Sweden)

    Tommaso Ranzani

    2015-08-01

    Full Text Available In this paper a simple but effective measuring system for endoluminal procedures is presented. The device allows measuring forces during the endoluminal manipulation of tissues with a standard surgical instrument for laparoscopic procedures. The force measurement is performed by recording both the forces applied directly by the surgeon at the instrument handle and the reaction forces on the access port. The measuring system was used to measure the forces necessary for appropriate surgical manipulation of tissues during transanal endoscopic microsurgery (TEM. Ex-vivo and in-vivo measurements were performed, reported and discussed. The obtained data can be used for developing and appropriately dimensioning novel dedicated instrumentation for TEM procedures.

  12. Vehicle Lateral State Estimation Based on Measured Tyre Forces

    OpenAIRE

    Tuononen, Ari J.

    2009-01-01

    Future active safety systems need more accurate information about the state of vehicles. This article proposes a method to evaluate the lateral state of a vehicle based on measured tyre forces. The tyre forces of two tyres are estimated from optically measured tyre carcass deflections and transmitted wirelessly to the vehicle body. The two remaining tyres are so-called virtual tyre sensors, the forces of which are calculated from the real tyre sensor estimates. The Kalman filter estimator for...

  13. Bite Mark Analysis

    Directory of Open Access Journals (Sweden)

    SK Padmakumar

    2014-07-01

    Full Text Available Bite mark analysis plays an important role in personal identi- fi cation in forensic odontology. They are commonly seen in violent crimes such as sexual assaults, homicides, child abuse, etc. Human bites are common on the face and are usually seen on prominent locations of the face such as the ears, nose and lips. Individual characteristics recorded in the bite marks such as fractures, rotations, attrition, and congenital malformations are helpful in identifying the individual who caused it. We are reporting the case of a 55-year-old lady with bite marks on her left ear, who was allegedly assaulted by the suspect. On the basis of characteristic features of the suspect’s dentition, it was concluded that the bite marks seen on the victim was most probably caused by the suspect.

  14. Displacement and Force Measurements with Quadrant Photodetector in Optical Tweezers

    Institute of Scientific and Technical Information of China (English)

    郭红莲; 刘春香; 李兆霖; 段建发; 韩学海; 程丙英; 张道中

    2003-01-01

    A technique of displacement and force measurements with a photodiode quadrant detector in an optical tweezers system is presented. The stiffness of optical trap is calibrated and the leukemia cell membrane tension is measured.The results show that the optical tweezers combined with the quadrant detector is a very useful tool for detecting the displacement and force with a millisecond-order response.

  15. Force Measurement on the GLAST Delta II Flight

    Science.gov (United States)

    Gordon, Scott; Kaufman, Daniel

    2009-01-01

    This viewgraph presentation reviews the interface force measurement at spacecraft separation of GLAST Delta II. The contents include: 1) Flight Force Measurement (FFM) Background; 2) Team Members; 3) GLAST Mission Overview; 4) Methodology Development; 5) Ground Test Validation; 6) Flight Data; 7) Coupled Loads Simulation (VCLA & Reconstruction); 8) Basedrive Simulation; 9) Findings; and 10) Summary and Conclusions.

  16. Recent Investments by NASA's National Force Measurement Technology Capability

    Science.gov (United States)

    Commo, Sean A.; Ponder, Jonathan D.

    2016-01-01

    The National Force Measurement Technology Capability (NFMTC) is a nationwide partnership established in 2008 and sponsored by NASA's Aeronautics Evaluation and Test Capabilities (AETC) project to maintain and further develop force measurement capabilities. The NFMTC focuses on force measurement in wind tunnels and provides operational support in addition to conducting balance research. Based on force measurement capability challenges, strategic investments into research tasks are designed to meet the experimental requirements of current and future aerospace research programs and projects. This paper highlights recent and force measurement investments into several areas including recapitalizing the strain-gage balance inventory, developing balance best practices, improving calibration and facility capabilities, and researching potential technologies to advance balance capabilities.

  17. Adhesion Force Measurements of Polymer Particles by Detachment Field Method

    Institute of Scientific and Technical Information of China (English)

    Masashi Nagayama; Nobuyasu Sakurai; Tatsuaki Wada; Manabu Takeuchi

    2004-01-01

    The adhesion force distributions of polymer particles to aluminum substrates were measured by the detachment field method. Polymer particles with conducting surface treatment were used for the measurements.Further the conventional detachment field method was modified to be applicable to the adhesion force measurements of a single particle. The adhesion force of the polymer particles increased with an increase in relative humidity. The surface roughness of the substrate influenced the adhesion forces of particles significantly. The influence of the CF4 plasma treatment of the polymer particles and thin layer coating of the substrate surface on the adhesion forces of the polymer particles was also studied, and factors affecting adhesion forces of polymer particles are discussed.

  18. Measurement of inter-particle forces by an interfacial force microscope

    Institute of Scientific and Technical Information of China (English)

    Qing Huang; Asghar Mesbah-Nejad; Seyed M. Tadayyon; Peter Norton; Hui Zhang; Jesse Zhu

    2010-01-01

    An inteffacial force microscope (IFM) was employed to measure the inter-particle forces between two individual glass beads with diameters varying from 8 to 20 μm. With the feedback function of IFM turned off, attractive forces were obtained. The forces varied in the range of 0.1-0.34 μN, and their validity was confirmed by a theoretical analysis of the van der Waals force between the same glass beads. With the feedback function switched on, no attractive forces between particles were detected by the IFM when the probe approached the sample substrate. This may be attributed to the dramatic change of the attractive forces within a very short separation distance and/or the relatively poor signal-to-noise ratio of the IFM.

  19. Friction measurements using force versus distance friction loops in force microscopy

    Science.gov (United States)

    Watson, G. S.; Dinte, B. P.; Blach-Watson, J. A.; Myhra, S.

    2004-07-01

    The atomic force microscope (AFM) allows investigation of the properties of surfaces and interfaces at atomic scale resolution. However, several different operational modes (imaging, force versus distance and lateral force), need to be deployed in order to gain insight into the structure, tribiological and mechanical properties. A new method, based on a variation of the force versus distance mode, has been developed. In essence, a coupling of the deformational modes of the probe is exploited whereby the tip is induced to undergo lateral travel in response to application of an out-of-plane force (and thus normal bending of the force-sensing lever). The lateral travel induces in-plane forces that are then measurable as a consequence of stimulation of the 'buckling' deformational mode of the lever. Outcomes will be demonstrated for atomically flat surfaces of WTe 2 and highly oriented pyrolytic graphite.

  20. A non-integral, axial-force measuring element

    Science.gov (United States)

    Ringel, M.; Levin, D.; Seginer, A.

    1989-10-01

    A new approach to the measurement of the axial force is presented. A nonintegral axial-force measuring element, housed within the wind-tunnel model, avoids the interactions that are caused by nonlinear elastic phenomena characteristic of integral balances. The new design overcomes other problems, such as friction, misalignment and relative motion between metric elements, that plagued previous attempts at separate measurement of the axial force. Calibration and test results prove the ability of the new approach to duplicate and even surpass the results of much more complicated and expensive integral balances. The advantages of the new design make it the best known solution for particular measurement problems.

  1. Micromechanical cohesion force measurements to determine cyclopentane hydrate interfacial properties.

    Science.gov (United States)

    Aman, Zachary M; Joshi, Sanjeev E; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

    2012-06-15

    Hydrate aggregation and deposition are critical factors in determining where and when hydrates may plug a deepwater flowline. We present the first direct measurement of structure II (cyclopentane) hydrate cohesive forces in the water, liquid hydrocarbon and gas bulk phases. For fully annealed hydrate particles, gas phase cohesive forces were approximately twice that obtained in a liquid hydrocarbon phase, and approximately six times that obtained in the water phase. Direct measurements show that hydrate cohesion force in a water-continuous bulk may be only the product of solid-solid cohesion. When excess water was present on the hydrate surface, gas phase cohesive forces increased by a factor of three, suggesting the importance of the liquid or quasi-liquid layer (QLL) in determining cohesive force. Hydrate-steel adhesion force measurements show that, when the steel surface is coated with hydrophobic wax, forces decrease up to 96%. As the micromechanical force technique is uniquely capable of measuring hydrate-surface forces with variable contact time, the present work contains significant implications for hydrate applications in flow assurance. PMID:22484169

  2. SU-8 force sensing pillar arrays for biological measurements.

    Science.gov (United States)

    Doll, Joseph C; Harjee, Nahid; Klejwa, Nathan; Kwon, Ronald; Coulthard, Sarah M; Petzold, Bryan; Goodman, Miriam B; Pruitt, Beth L

    2009-05-21

    The generation and sensation of mechanical force plays a role in many dynamic biological processes, including touch sensation. This paper presents a two-axis micro strain gauge force sensor constructed from multiple layers of SU-8 and metal on quartz substrates. The sensor was designed to meet requirements for measuring tactile sensitivity and interaction forces exerted during locomotion by small organisms such as the nematode Caenorhabditis elegans. The device is transparent and compatible with light microscopes, allowing behavioral experiments to be combined with quantitative force measurements. For the first time, we have characterized the scale of interaction forces generated in wild-type C. elegans in probing and responding to their environment during locomotion. The device features sub-microN force resolution from 1 Hz to 1 kHz, >25 microN range, kHz acquisition rates and biocompatibility. PMID:19417913

  3. Emissivity measurements with an Atomic Force Microscope

    OpenAIRE

    van Zwol, Pieter Jan; Ranno, Laurent; Chevrier, Joel

    2011-01-01

    We show that functionalized micromechanical bilayer levers can be used as sensitive probes to accurately measure radiative heat flux in vacuum between two materials at the micro scale. By means of calibration to one material these measurements can be made quantitative for radiative heat flux or for either temperature or material emissivity. We discuss issues and opportunities for our method and provide ample technical details regarding its implementation and demonstrate good correspondence wi...

  4. A Simple Method for Measuring Tensile Force with Piezoelectric Patch

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-Wen; JIANG Zhong-Wei; Testuya Morisaki

    2007-01-01

    @@ We propose a simple method for monitoring the axial tensile and compressive force in a structure by using a piezoelectric patch with the piezoelectric impedance based measurement. A simple approximate equation for estimating the tensile force in two different conditions, which can be calculated easily if the natural frequencies in two different states are measured, is explained in detail. On another front, the natural frequency can be very easily measured by a piezoelectric element by bonding it on the measuring subject structure, because its electric impedance of piezoelement is related to the structural mechanical impedance. Furthermore, an experiment for measuring a tensile force in a simple supported beam is carried out for validating the proposed method. The results show a good accuracy in estimating the tensile force variation by the natural frequency change measured from the piezoelement.

  5. Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces

    Directory of Open Access Journals (Sweden)

    Adam Sweetman

    2014-04-01

    Full Text Available In principle, non-contact atomic force microscopy (NC-AFM now readily allows for the measurement of forces with sub-nanonewton precision on the atomic scale. In practice, however, the extraction of the often desired ‘short-range’ force from the experimental observable (frequency shift is often far from trivial. In most cases there is a significant contribution to the total tip–sample force due to non-site-specific van der Waals and electrostatic forces. Typically, the contribution from these forces must be removed before the results of the experiment can be successfully interpreted, often by comparison to density functional theory calculations. In this paper we compare the ‘on-minus-off’ method for extracting site-specific forces to a commonly used extrapolation method modelling the long-range forces using a simple power law. By examining the behaviour of the fitting method in the case of two radically different interaction potentials we show that significant uncertainties in the final extracted forces may result from use of the extrapolation method.

  6. Probing Anisotropic Surface Properties of Molybdenite by Direct Force Measurements.

    Science.gov (United States)

    Lu, Zhenzhen; Liu, Qingxia; Xu, Zhenghe; Zeng, Hongbo

    2015-10-27

    Probing anisotropic surface properties of layer-type mineral is fundamentally important in understanding its surface charge and wettability for a variety of applications. In this study, the surface properties of the face and the edge surfaces of natural molybdenite (MoS2) were investigated by direct surface force measurements using atomic force microscope (AFM). The interaction forces between the AFM tip (Si3N4) and face or edge surface of molybdenite were measured in 10 mM NaCl solutions at various pHs. The force profiles were well-fitted with classical DLVO (Derjaguin-Landau-Verwey-Overbeek) theory to determine the surface potentials of the face and the edge surfaces of molybdenite. The surface potentials of both the face and edge surfaces become more negative with increasing pH. At neutral and alkaline conditions, the edge surface exhibits more negative surface potential than the face surface, which is possibly due to molybdate and hydromolybdate ions on the edge surface. The point of zero charge (PZC) of the edge surface was determined around pH 3 while PZC of the face surface was not observed in the range of pH 3-11. The interaction forces between octadecyltrichlorosilane-treated AFM tip (OTS-tip) and face or edge surface of molybdenite were also measured at various pHs to study the wettability of molybdenite surfaces. An attractive force between the OTS-tip and the face surface was detected. The force profiles were well-fitted by considering DLVO forces and additional hydrophobic force. Our results suggest the hydrophobic feature of the face surface of molybdenite. In contrast, no attractive force between the OTS-tip and the edge surface was detected. This is the first study in directly measuring surface charge and wettability of the pristine face and edge surfaces of molybdenite through surface force measurements. PMID:26434695

  7. Direct measurement of the forces generated by an undulatory microswimmer

    Science.gov (United States)

    Schulman, Rafael; Backholm, Matilda; Ryu, William; Dalnoki-Veress, Kari

    2014-11-01

    C. elegans is a millimeter-sized nematode which has served as a model organism in biology for several decades, primarily due to its simple anatomy. Employing an undulatory form of locomotion, this worm is capable of propelling itself through various media. Using a micropipette deflection technique, in conjunction with high speed imaging, we directly measure the time-varying forces generated by C. elegans. We observe excellent agreement between our measured forces and the predictions of resistive force theory, through which we determine the drag coefficients of the worm. We also perform the direct force measurements at controlled distances from a single solid boundary as well as between two solid boundaries. We extract the drag coefficients of the worm to quantify the influence of the boundary on the swimming and the hydrodynamic forces involved.

  8. 咀嚼压力增强对大鼠牙槽骨白细胞介素-1β表达的影响%Effect of increased bite force on the expression of IL-1β in rat alveolar bone osteoblasts

    Institute of Scientific and Technical Information of China (English)

    袁林; 周伟东; 赵云凤

    2001-01-01

    目的检测大鼠牙槽骨成骨细胞中IL-1β在正常及增强咀嚼压力状态下的动态表达,探讨IL-1β在牙槽骨改建中的分子机制。方法采用HE染色和免疫组化的方法,观察牙周形态变化以及牙槽骨成骨细胞中IL-1β蛋白表达。结果生理限度内咀嚼压力增强时,形态学显示大鼠牙周膜增宽、牙槽骨新骨形成;免疫组化观察到成骨细胞中IL-1β表达较正常咀嚼压力时明显增强。结论咀嚼压力增强促使牙周组织产生IL-1β明显增多,诱发了破骨功能,同时,还激活了成骨功能。提示IL-1β在咀嚼压力影响牙槽骨改建的过程中起着重要的调节作用。%Objective To explore the molecular mechanism of alveolar bone remodeling by studying the dynamic changes of IL- 1β expression in rat alveolar bone osteoblasts. Methods Rat models of increased bite force of the back teeth were established, and the expression of IL-1β in the alveolar bone osteoblasts were determined by HE staining and immunohistochemistry. Observation of the changes in the histological morphology of the periodontium was conducted microscopically. Rats with normal bite force served as control. Results The increase of bite force (within the physiological limit) induced the widening of the periodontal ligament and the osteogenesis in the alveolar bone. Significant enhancement of IL-1β expression was observed in the osteoblasts of rats with increased bite force, in comparison with that in the rats with normal bite force. Conclusion Increased bite force causes higher expression levels of IL-1β in the alveolar bone osteoblasts, initiating the destruction process of the bone but simultaneously the activation of the ossification, suggesting that IL-1β plays an important role in the regulation of periodontium remodeling in response to changes in the bite force

  9. Force Measurements in Magnetic Suspension and Balance System

    Science.gov (United States)

    Kuzin, Alexander; Shapovalov, George; Prohorov, Nikolay

    1996-01-01

    The description of an infrared telemetry system for measurement of drag forces in Magnetic Suspension and Balance Systems (MSBS) is presented. This system includes a drag force sensor, electronic pack and transmitter placed in the model which is of special construction, and receiver with a microprocessor-based measuring device, placed outside of the test section. Piezosensitive resonators as sensitive elements and non-magnetic steel as the material for the force sensor are used. The main features of the proposed system for load measurements are discussed and the main characteristics are presented.

  10. Vehicle Lateral State Estimation Based on Measured Tyre Forces

    Directory of Open Access Journals (Sweden)

    Ari J. Tuononen

    2009-10-01

    Full Text Available Future active safety systems need more accurate information about the state of vehicles. This article proposes a method to evaluate the lateral state of a vehicle based on measured tyre forces. The tyre forces of two tyres are estimated from optically measured tyre carcass deflections and transmitted wirelessly to the vehicle body. The two remaining tyres are so-called virtual tyre sensors, the forces of which are calculated from the real tyre sensor estimates. The Kalman filter estimator for lateral vehicle state based on measured tyre forces is presented, together with a simple method to define adaptive measurement error covariance depending on the driving condition of the vehicle. The estimated yaw rate and lateral velocity are compared with the validation sensor measurements.

  11. Thigh-calf contact force measurements in deep knee flexion.

    NARCIS (Netherlands)

    Zelle, J.G.; Barink, M.; Loeffen, R.; Waal Malefijt, M.C. de; Verdonschot, N.J.J.

    2007-01-01

    BACKGROUND: Knee models often do not contain thigh-calf contact which occurs in deep knee flexion. Thigh-calf contact is expected to reduce muscle forces and thereby affects internal stresses in the knee joint. The purpose of this study was to measure thigh-calf contact forces. Two deep knee flexion

  12. Reduction of Liquid Bridge Force for 3D Microstructure Measurements

    Directory of Open Access Journals (Sweden)

    Hiroshi Murakami

    2016-05-01

    Full Text Available Recent years have witnessed an increased demand for a method for precise measurement of the microstructures of mechanical microparts, microelectromechanical systems, micromolds, optical devices, microholes, etc. This paper presents a measurement system for three-dimensional (3D microstructures that use an optical fiber probe. This probe consists of a stylus shaft with a diameter of 2.5 µm and a glass ball with a diameter of 5 µm attached to the stylus tip. In this study, the measurement system, placed in a vacuum vessel, is constructed suitably to prevent adhesion of the stylus tip to the measured surface caused by the surface force resulting from the van der Waals force, electrostatic force, and liquid bridge force. First, these surface forces are analyzed with the aim of investigating the causes of adhesion. Subsequently, the effects of pressure inside the vacuum vessel on surface forces are evaluated. As a result, it is found that the surface force is 0.13 µN when the pressure inside the vacuum vessel is 350 Pa. This effect is equivalent to a 60% reduction in the surface force in the atmosphere.

  13. Measuring Air Force Contracting customer satisfaction

    OpenAIRE

    Davis, Jamie

    2015-01-01

    Approved for public release; distribution is unlimited This research gathers background information to identify which customer satisfaction elements should be included in a standardized tool that measures the level of customer satisfaction for AF Contracting’s external and internal customers. This research conducts a comprehensive literature review of the prominent customer satisfaction trends, while exploring the idiosyncrasies of customer satisfaction that are unique to AF Contracting. F...

  14. Fire Ant Bites

    Science.gov (United States)

    ... Favorite Name: Category: Share: Yes No, Keep Private Fire Ant Bites Share | Fire ants are aggressive, venomous insects that have pinching ... across the United States, even into Puerto Rico. Fire ant stings usually occur on the feet or ...

  15. Rat Bite Fever

    Science.gov (United States)

    ... is followed 3 to 10 days later by: Fever and chills Headache Skin rash (mostly on the arms and ... 21 days later, the following symptoms may surface: Fever and chills Headache Ulceration at the site of the bite ...

  16. Tick Bites, First Aid

    Science.gov (United States)

    ... rashes clinical tools newsletter | contact Share | Tick Bites, First Aid A A A It is important to inspect ... temporary paralysis in their host (called tick paralysis). First Aid Guide To remove an embedded tick: Wash your ...

  17. Topological and geometric measurements of force chain structure

    CERN Document Server

    Giusti, Chad; Owens, Eli T; Daniels, Karen E; Bassett, Danielle S

    2016-01-01

    Developing quantitative methods for characterizing structural properties of force chains in densely packed granular media is an important step toward understanding or predicting large-scale physical properties of a packing. A promising framework in which to develop such methods is network science, which can be used to translate particle locations and force contacts to a graph in which particles are represented by nodes and forces between particles are represented by weighted edges. Applying network-based community-detection techniques to extract force chains opens the door to developing statistics of force chain structure, with the goal of identifying shape differences across packings, and providing a foundation on which to build predictions of bulk material properties from mesoscale network features. Here, we discuss a trio of related but fundamentally distinct measurements of mesoscale structure of force chains in arbitrary 2D packings, including a novel statistic derived using tools from algebraic topology...

  18. Quantum metrology. Optically measuring force near the standard quantum limit.

    Science.gov (United States)

    Schreppler, Sydney; Spethmann, Nicolas; Brahms, Nathan; Botter, Thierry; Barrios, Maryrose; Stamper-Kurn, Dan M

    2014-06-27

    The Heisenberg uncertainty principle sets a lower bound on the noise in a force measurement based on continuously detecting a mechanical oscillator's position. This bound, the standard quantum limit, can be reached when the oscillator subjected to the force is unperturbed by its environment and when measurement imprecision from photon shot noise is balanced against disturbance from measurement back-action. We applied an external force to the center-of-mass motion of an ultracold atom cloud in a high-finesse optical cavity and measured the resulting motion optically. When the driving force is resonant with the cloud's oscillation frequency, we achieve a sensitivity that is a factor of 4 above the standard quantum limit and consistent with theoretical predictions given the atoms' residual thermal disturbance and the photodetection quantum efficiency.

  19. Surface force measurement of ultraviolet nanoimprint lithography materials

    Science.gov (United States)

    Taniguchi, Jun; Hasegawa, Masayuki; Amemiya, Hironao; Kobayashi, Hayato

    2016-02-01

    Ultraviolet nanoimprint lithography (UV-NIL) has advantages such as room-temperature operation, high through-put, and high resolution. In the UV-NIL process, the mold needs a release coating material to prevent adhesion of the transfer resin. Usually, fluorinated silane coupling agents are used as release coating materials. To evaluate the release property, surface force analyzer equipment was used. This equipment can measure the surface forces between release-coated or noncoated mold material surfaces and UV-cured resin surfaces in the solid state. Lower surface forces were measured when a release coating was used on the mold material surface.

  20. Application of Lorentz force techniques for flow rate measurement

    Science.gov (United States)

    Ebert, Reschad Johann; Resagk, Christian

    2014-11-01

    We report on the progress of the Lorentz force velocimetry (LFV): a contactless non-invasive flow velocity measurement technique. This method has been developed and demonstrated for various applications in our institute and in industry. At applications for weakly conducting fluids such as electrolytes with conductivities in the range of 1 - 10 S/m the challenging bottleneck is the detection of the tiny Lorentz forces in the noisy environment of the test channel. For the force measurement a state-of-the-art electromagnetic force compensation balance is used. Due to this device the mass of the Lorentz force generating magnets is limited. For enabling larger magnet systems and for higher force signals we have developed and tested a buoyancy based weight force compensation method which will be presented here. Additionally, results of LFV measurements at non-symmetric fluid profiles will be shown. By that an evaluation of the feasibility of this measurement principle for disturbed fluid profiles that are relevant for developing the LFV for weakly conducting fluids towards industrial applications can be made. Additionally a prospective setup for using the LFV for molten salt flows will be explained.

  1. Does an instrumented treadmill correctly measure the ground reaction forces?

    Directory of Open Access Journals (Sweden)

    Patrick A. Willems

    2013-11-01

    Since the 1990s, treadmills have been equipped with multi-axis force transducers to measure the three components of the ground reaction forces during walking and running. These measurements are correctly performed if the whole treadmill (including the motor is mounted on the transducers. In this case, the acceleration of the treadmill centre of mass relative to the reference frame of the laboratory is nil. The external forces exerted on one side of the treadmill are thus equal in magnitude and opposite in direction to the external forces exerted on the other side. However, uncertainty exists about the accuracy of these measures: due to friction between the belt and the tread-surface, due to the motor pulling the belt, some believe that it is not possible to correctly measure the horizontal components of the forces exerted by the feet on the belt. Here, we propose a simple model of an instrumented treadmill and we demonstrate (1 that the forces exerted by the subject moving on the upper part of the treadmill are accurately transmitted to the transducers placed under it and (2 that all internal forces – including friction – between the parts of the treadmill are cancelling each other.

  2. Flight Force Measurements on a Spacecraft to Launch Vehicle Interface

    Science.gov (United States)

    Kaufman, Daniel S.; Gordon, Scott A.

    2012-07-01

    For several years we had wanted to measure interface forces between a launch vehicle and the Payload. Finally in July 2006 a proposal was made and funded to evaluate the use of flight force measurements (FFM) to improve the loads process of a Spacecraft in its design and test cycle. A NASA/Industry team was formed, the core Team consisted of 20 people. The proposal identified two questions that this assessment would attempt to address by obtaining the flight forces. These questions were: 1) Is flight correlation and reconstruction with acceleration methods sufficient? 2) How much can the loads and therefore the design and qualification be reduced by having force measurements? The objective was to predict the six interface driving forces between the Spacecraft and the Launch Vehicle throughout the boost phase. Then these forces would be compared with reconstructed loads analyses for evaluation in an attempt to answer them. The paper will present the development of a strain based force measurement system and also an acceleration method, actual flight results, post flight evaluations and lessons learned.

  3. The Kilogram and Measurements of Mass and Force.

    Science.gov (United States)

    Jabbour, Z J; Yaniv, S L

    2001-01-01

    This paper describes the facilities, measurement capabilities, and ongoing research activities in the areas of mass and force at the National Institute of Standards and Technology (NIST). The first section of the paper is devoted to mass metrology and starts with a brief historical perspective on the developments that led to the current definition of the kilogram. An overview of mass measurement procedures is given with a brief discussion of current research on alternative materials for mass standards and surface profiles of the U.S. national prototype kilograms. A brief outlook into the future possible redefinition of the unit of mass based on fundamental principles is included. The second part of this paper focuses on the unit of force and describes the realization of the unit, measurement procedures, uncertainty in the realized force, facilities, and current efforts aimed at the realization of small forces.

  4. Video measurements of instantaneous forces of flapping wing vehicles

    Science.gov (United States)

    Jennings, Alan; Mayhew, Michael; Black, Jonathan

    2015-12-01

    Flapping wings for small aerial vehicles have revolutionary potential for maneuverability and endurance. Ornithopters fail to achieve the performance of their biological equivalents, despite extensive research on how animals fly. Flapping wings produce peak forces due to the stroke reversal of the wing. This research demonstrates in-flight measurements of an ornithopter through the use of image processing, specifically measuring instantaneous forces. Results show that the oscillation about the flight path is significant, being about 20% of the mean velocity and up to 10 g's. Results match forces with deformations of the wing to contrast the timing and wing shape of the upstroke and the downstroke. Holding the vehicle fixed (e.g. wind tunnel testing or simulations) structural resonance is affected along with peak forces, also affecting lift. Non-contact, in-flight measurements are proposed as the best method for matching the flight conditions of flapping wing vehicles.

  5. NASA ATP Force Measurement Technology Capability Strategic Plan

    Science.gov (United States)

    Rhew, Ray D.

    2008-01-01

    The Aeronautics Test Program (ATP) within the National Aeronautics and Space Administration (NASA) Aeronautics Research Mission Directorate (ARMD) initiated a strategic planning effort to re-vitalize the force measurement capability within NASA. The team responsible for developing the plan included members from three NASA Centers (Langley, Ames and Glenn) as well as members from the Air Force s Arnold Engineering and Development Center (AEDC). After visiting and discussing force measurement needs and current capabilities at each participating facility as well as selected force measurement companies, a strategic plan was developed to guide future NASA investments. This paper will provide the details of the strategic plan and include asset management, organization and technology research and development investment priorities as well as efforts to date.

  6. Towards a Casimir Force Measurement between Micromachined Parallel Plate Structures

    Directory of Open Access Journals (Sweden)

    Remco J. Wiegerink

    2012-11-01

    Full Text Available Ever since its prediction, experimental investigation of the Casimir force has been of great scientific interest. Many research groups have successfully attempted quantifying the force with different device geometries; however, measurement of the Casimir force between parallel plates with sub-micron separation distance is still a challenging task, since it becomes extremely difficult to maintain sufficient parallelism between the plates. The Casimir force can significantly influence the operation of micro devices and to realize reliable and reproducible devices it is necessary to understand and experimentally verify the influence of the Casimir force at sub-micron scale. In this paper, we present the design principle, fabrication and characterization of micromachined parallel plate structures that could allow the measurement of the Casimir force with tunable separation distance in the range of 100 to 1000 nm. Initially, a gold coated parallel plate structure is explored to measure the Casimir force, but also other material combinations could be investigated. Using gold-silicon eutectic bonding, a reliable approach to bond chips with integrated suspended plates together with a well-defined separation distance in the order of 1–2 μm is developed.

  7. Designing an experiment to measure cellular interaction forces

    Science.gov (United States)

    McAlinden, Niall; Glass, David G.; Millington, Owain R.; Wright, Amanda J.

    2013-09-01

    Optical trapping is a powerful tool in Life Science research and is becoming common place in many microscopy laboratories and facilities. The force applied by the laser beam on the trapped object can be accurately determined allowing any external forces acting on the trapped object to be deduced. We aim to design a series of experiments that use an optical trap to measure and quantify the interaction force between immune cells. In order to cause minimum perturbation to the sample we plan to directly trap T cells and remove the need to introduce exogenous beads to the sample. This poses a series of challenges and raises questions that need to be answered in order to design a set of effect end-point experiments. A typical cell is large compared to the beads normally trapped and highly non-uniform - can we reliably trap such objects and prevent them from rolling and re-orientating? In this paper we show how a spatial light modulator can produce a triple-spot trap, as opposed to a single-spot trap, giving complete control over the object's orientation and preventing it from rolling due, for example, to Brownian motion. To use an optical trap as a force transducer to measure an external force you must first have a reliably calibrated system. The optical trapping force is typically measured using either the theory of equipartition and observing the Brownian motion of the trapped object or using an escape force method, e.g. the viscous drag force method. In this paper we examine the relationship between force and displacement, as well as measuring the maximum displacement from equilibrium position before an object falls out of the trap, hence determining the conditions under which the different calibration methods should be applied.

  8. Deconvolution Kalman filtering for force measurements of revolving wings

    Science.gov (United States)

    Vester, R.; Percin, M.; van Oudheusden, B.

    2016-09-01

    The applicability of a deconvolution Kalman filtering approach is assessed for the force measurements on a flat plate undergoing a revolving motion, as an alternative procedure to correct for test setup vibrations. The system identification process required for the correct implementation of the deconvolution Kalman filter is explained in detail. It is found that in the presence of a relatively complex forcing history, the DK filter is better suited to filter out structural test rig vibrations than conventional filtering techniques that are based on, for example, low-pass or moving-average filtering. The improvement is especially found in the characterization of the generated force peaks. Consequently, more reliable force data is obtained, which is vital to validate semi-empirical estimation models, but is also relevant to correlate identified flow phenomena to the force production.

  9. Fiber optic micro sensor for the measurement of tendon forces

    Science.gov (United States)

    2012-01-01

    A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The metal housings were fabricated by several methods including laser micromachining, swaging, and hydroforming. Designs are presented that allow for simultaneous temperature and force measurements as well as for simultaneous resolution of multi-axis forces. The sensor was experimentally evaluated by hydrostatic loading and in vitro testing. A commercial hydraulic burst tester was used to provide uniform pressures on the sensor in order to establish the linearity, repeatability, and accuracy characteristics of the sensor. The in vitro experiments were performed in excised tendon and in a dynamic gait simulator to simulate biological conditions. In both experimental conditions, the sensor was found to be a sensitive and reliable method for acquiring minimally invasive measurements of soft tissue forces. Our results suggest that this sensor will prove useful in a variety of biomechanical measurements. PMID:23033868

  10. Fiber optic micro sensor for the measurement of tendon forces

    Directory of Open Access Journals (Sweden)

    Behrmann Gregory P

    2012-10-01

    Full Text Available Abstract A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The metal housings were fabricated by several methods including laser micromachining, swaging, and hydroforming. Designs are presented that allow for simultaneous temperature and force measurements as well as for simultaneous resolution of multi-axis forces. The sensor was experimentally evaluated by hydrostatic loading and in vitro testing. A commercial hydraulic burst tester was used to provide uniform pressures on the sensor in order to establish the linearity, repeatability, and accuracy characteristics of the sensor. The in vitro experiments were performed in excised tendon and in a dynamic gait simulator to simulate biological conditions. In both experimental conditions, the sensor was found to be a sensitive and reliable method for acquiring minimally invasive measurements of soft tissue forces. Our results suggest that this sensor will prove useful in a variety of biomechanical measurements.

  11. Dynamic steering beams for efficient force measurement in optical manipulation

    Institute of Scientific and Technical Information of China (English)

    Xiaocong Yuan; Yuquan Zhang; Rui Cao; Xing Zhao; Jing Bu; Siwei Zhu

    2011-01-01

    @@ An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported.Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium.The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force.The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead.The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.%An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported. Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium. The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force. The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead. The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.

  12. A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope

    OpenAIRE

    Manfred Lange; Dennis van Vörden; Rolf Möller

    2012-01-01

    Measurements of the frequency shift versus distance in noncontact atomic force microscopy (NC-AFM) allow measurements of the force gradient between the oscillating tip and a surface (force-spectroscopy measurements). When nonconservative forces act between the tip apex and the surface the oscillation amplitude is damped. The dissipation is caused by bistabilities in the potential energy surface of the tip–sample system, and the process can be understood as a hysteresis of forces between...

  13. Evaluación electromiográfica de los músculos masticadores durante la fuerza máxima de mordedura Electromyography evaluations of the masticator muscles during the maximum bite force

    Directory of Open Access Journals (Sweden)

    M.J.P. Coelho-Ferraz

    2008-12-01

    Full Text Available La actividad de los músculos masetero y de la porción anterior temporal de ambos lados, derecho e izquierdo, respectivamente, durante la fuerza máxima de mordedura fue estudiada en voluntarios sanos. El estudio incluyó a 17 voluntarios adultos de ambos sexos, edad promedia de 25 años, que no evidenciaban ningún indicio de disfunción temporomandibular y eran relacionados con la Facultad de Odontología de Piracicaba. Se registraron los datos electromiográficos en ambos lados de la cara del masetero y de la porción anterior de los músculos temporal y suprahioideo en las posiciones postural e isométrica. Se utilizaron electrodos de superficie pasivos para niños, de Ag/AgCl, con forma circular y descargables de Meditrace® Kendall-LTP, modelo Chicopee MA01. Éstos se conectaron a un preamplificador con una ganancia de 20x que formaba un circuito de diferenciales. Se captaron los registros de las señales eléctricas utilizando un equipo EMG-8OOC de EMG System of Brazil, Ltd., de ocho canales, a una frecuencia de 2 KHz con 16 bitios de resolución y un filtro digital con un paso de banda de 20 a 500 Hz. Se utilizó también un transductor de presión que consistía en un tubo de goma con un sensor de presión (MPX 5700* (Motorola SPS, Austin, TX, EE.UU. para registrar la fuerza máxima de mordedura. El análisis estadístico incluyó la correlación lineal, la prueba t emparejada y el análisis de la varianza. Se consideró estadísticamente significativa una probabilidad de pHealthy individuals were examined in terms of the pattern of activity of the masseter and temporal muscles in their anterior portion of both right and left sides, respectively, with the maximum bite force. The study consisted in seventeen adult volunteers with no sign of apparent temporomandibular dysfunction, of both genders, connected to the School of Dentistry of Piracicaba, with average age of 25 years old. The electromyography data were obtained, bilaterally, of

  14. Optically Measuring Force near the Standard Quantum Limit

    CERN Document Server

    Schreppler, Sydney; Brahms, Nathan; Botter, Thierry; Barrios, Maryrose; Stamper-Kurn, Dan M

    2013-01-01

    The Heisenberg uncertainty principle sets a lower bound on the sensitivity of continuous optical measurements of force. This bound, the standard quantum limit, can only be reached when a mechanical oscillator subjected to the force is unperturbed by its environment, and when measurement imprecision from photon shot-noise is balanced against disturbance from measurement backaction. We apply an external force to the center-of-mass motion of an ultracold atom cloud in a high-finesse optical cavity. The optomechanically transduced response clearly demonstrates the trade-off between measurement imprecision and back-action noise. We achieve a sensitivity that is consistent with theoretical predictions for the quantum limit given the atoms' slight residual thermal disturbance and the photodetection quantum efficiency, and is a factor of 4 above the absolute standard quantum limit.

  15. WP/084 Measuring Industry Agglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Tarp, Finn; Newman, Carol

    Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance of transp...

  16. Capillary-force measurement on SiC surfaces

    Science.gov (United States)

    Sedighi, M.; Svetovoy, V. B.; Palasantzas, G.

    2016-06-01

    Capillary forces have been measured by atomic force microscopy in the sphere-plate geometry, in a controlled humidity environment, between smooth silicon carbide and borosilicate glass spheres. The force measurements were performed as a function of the rms surface roughness ˜4-14 nm mainly due to sphere morphology, the relative humidity (RH) ˜0%-40%, the applied load on the cantilever, and the contact time. The pull-off force was found to decrease by nearly two orders of magnitude with increasing rms roughness from 8 to 14 nm due to formation of a few capillary menisci for the roughest surfaces, while it remained unchanged for rms roughness <8 nm implying fully wetted surface features leading to a single meniscus. The latter reached a steady state in less than 5 s for the smoothest surfaces, as force measurements versus contact time indicated for increased RH˜40%. Finally, the pull-off force increases and reaches a maximum with applied load, which is associated with plastic deformation of surface asperities, and decreases at higher loads.

  17. Capillary-force measurement on SiC surfaces.

    Science.gov (United States)

    Sedighi, M; Svetovoy, V B; Palasantzas, G

    2016-06-01

    Capillary forces have been measured by atomic force microscopy in the sphere-plate geometry, in a controlled humidity environment, between smooth silicon carbide and borosilicate glass spheres. The force measurements were performed as a function of the rms surface roughness ∼4-14 nm mainly due to sphere morphology, the relative humidity (RH) ∼0%-40%, the applied load on the cantilever, and the contact time. The pull-off force was found to decrease by nearly two orders of magnitude with increasing rms roughness from 8 to 14 nm due to formation of a few capillary menisci for the roughest surfaces, while it remained unchanged for rms roughness <8 nm implying fully wetted surface features leading to a single meniscus. The latter reached a steady state in less than 5 s for the smoothest surfaces, as force measurements versus contact time indicated for increased RH∼40%. Finally, the pull-off force increases and reaches a maximum with applied load, which is associated with plastic deformation of surface asperities, and decreases at higher loads. PMID:27415337

  18. [Structural changes in the periodontal tissues under measured exposure to intra- and extraoral orthodontic appliances in the unstable bite].

    Science.gov (United States)

    Panikarovskiĭ, V V; Grigor'ian, A S; Starosvetskiĭ, S I; Antipova, Z P

    1995-01-01

    Study of the histological characteristics of the teeth, dental rudiments, and periodontal tissues of animals during distraction of the maxilla and distal dislocation of the mandible by "minor", "medium", and "strong" force showed that the type and degree of morphological changes are related to the strength of exposure and duration of orthodontist device application. The minor (1.2 H) and medium (2.5 H) force did not injure the studied structural elements of the periodical complex. Exposure of osseous tissues to a strong (5.0 H) force surpassing the compensatory potential of this tissue caused a complex of changes characterized by predominance of the processes of destruction of bone matter, specifically, by its resorption over its regeneration. These processes were the most evident during distal dislocation of the mandible. Appreciable foci of resorption were observed not only in the alveolar process bone, but in hard tissues (dentin and cement) of deciduous teeth as well. These results demonstrate the necessity of a careful approach to the choice of the intensity of force developed by various orthodontist devices.

  19. Combined atomic force microscopy and voltage pulse technique to accurately measure electrostatic force

    Science.gov (United States)

    Inami, Eiichi; Sugimoto, Yoshiaki

    2016-08-01

    We propose a new method of extracting electrostatic force. The technique is based on frequency modulation atomic force microscopy (FM-AFM) combined with a voltage pulse. In this method, the work that the electrostatic field does on the oscillating tip is measured through the cantilever energy dissipation. This allows us to directly extract capacitive forces including the longer range part, to which the conventional FM-AFM is insensitive. The distance-dependent contact potential difference, which is modulated by local charges distributed on the surfaces of the tip and/or sample, could also be correctly obtained. In the absence of local charges, our method can perfectly reproduce the electrostatic force as a function of the distance and the bias voltage. Furthermore, we demonstrate that the system serves as a sensitive sensor enabling us to check the existence of the local charges such as trapped charges and patch charges.

  20. Simulation of a flow around biting teeth

    Science.gov (United States)

    Narusawa, Hideaki; Yamamoto, Eriko; Kuwahara, Kunio

    2008-11-01

    We simulated a flow around biting teeth. The decayed tooth is a disease that a majority of people are annoyed. These are often generated from a deep groove at occlusal surface. It is known that a person who bites well doesn't suffer from a decayed tooth easily. Biting forces reach as much as 60 kg/cm^2 by an adult male, and when chewing, upper and lower teeth approach to bite by those forces. The crushed food mixed with saliva becomes high viscosity fluid, and is pushed out of ditches of teeth in the direction of the cheek or the tongue. Teeth with complex three dimension curved surface are thought to form venturi at this time, and to generate big pressure partially. An excellent dental articulation will possibly help a natural generation of a flow to remove dental plaque, i.e. the cause of the decayed tooth. Moreover, the relation of this flow with the destruction of the filled metal or the polymer is doubted. In this research, we try to clarify the pressure distributions by this flow generation as well as its dynamics when chewing. One of our goals is to enable an objective design of the shape of the dental fillings and the artificial tooth. Tooth has a very small uneven ground and a bluff body. In this case, to calculate a computational numerical simulation to solve the Navier-Stokes equations three dimension Cartesian coordinate system is employed.

  1. Mosquito Bite Prevention For Travelers

    Science.gov (United States)

    Mosquito Bite Prevention for Travelers Mosquitoes spread many types of viruses and parasites that can cause diseases ... be available. Protect yourself and your family from mosquito bites. Here’s how: Keep mosquitoes out of your ...

  2. Animal bite - first aid - slideshow

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/presentations/100214.htm Animal bite - first aid - series To use the sharing ... D.A.M., Inc. Related MedlinePlus Health Topics Animal Bites A.D.A.M., Inc. is accredited ...

  3. Insect bite reactions

    Directory of Open Access Journals (Sweden)

    Sanjay Singh

    2013-01-01

    Full Text Available Insects are a class of living creatures within the arthropods. Insect bite reactions are commonly seen in clinical practice. The present review touches upon the medically important insects and their places in the classification, the sparse literature on the epidemiology of insect bites in India, and different variables influencing the susceptibility of an individual to insect bites. Clinical features of mosquito bites, hypersensitivity to mosquito bites Epstein-Barr virus NK (HMB-EBV-NK disease, eruptive pseudoangiomatosis, Skeeter syndrome, papular pruritic eruption of HIV/AIDS, and clinical features produced by bed bugs, Mexican chicken bugs, assassin bugs, kissing bugs, fleas, black flies, Blandford flies, louse flies, tsetse flies, midges, and thrips are discussed. Brief account is presented of the immunogenic components of mosquito and bed bug saliva. Papular urticaria is discussed including its epidemiology, the 5 stages of skin reaction, the SCRATCH principle as an aid in diagnosis, and the recent evidence supporting participation of types I, III, and IV hypersensitivity reactions in its causation is summarized. Recent developments in the treatment of pediculosis capitis including spinosad 0.9% suspension, benzyl alcohol 5% lotion, dimethicone 4% lotion, isopropyl myristate 50% rinse, and other suffocants are discussed within the context of evidence derived from randomized controlled trials and key findings of a recent systematic review. We also touch upon a non-chemical treatment of head lice and the ineffectiveness of egg-loosening products. Knockdown resistance (kdr as the genetic mechanism making the lice nerves insensitive to permethrin is discussed along with the surprising contrary clinical evidence from Europe about efficacy of permethrin in children with head lice carrying kdr-like gene. The review also presents a brief account of insects as vectors of diseases and ends with discussion of prevention of insect bites and some

  4. Optical Fiber Grating Sensor for Force Measurement of Anchor Cable

    Institute of Scientific and Technical Information of China (English)

    JIANG Desheng; FU Jinghua; LIU Shengchun; SUI Lingfeng; FU Rong

    2006-01-01

    The development of the sensor suitable for measuring large load stress to the anchor cable becomes an important task in bridge construction and maintenance. Therefore, a new type of optical fiber sensor was developed in the laboratory - optical fiber grating sensor for force measurement of anchor cable (OFBFMAC). No similar report about this kind of sensor has been found up to now in China and other countries. This sensor is proved to be an effective way of monitoring in processes of anchor cable installation, cable cutting, cable force regulation, etc, with the accurate and repeatable measuring results. Its successful application in the tie bar cable force safety monitoring for Wuhan Qingchuan bridge is a new exploration of optical fiber grating sensing technology in bridge tie bar monitoring system.

  5. Direct thrust force measurement of pulse detonation engine

    Science.gov (United States)

    Wahid, Mazlan Abdul; Faiz, M. Z. Ahmad; Saqr, Khalid M.

    2012-06-01

    In this paper we present the result of High-Speed Reacting Flow Laboratory (HiREF) pulse detonation engine (PDE) experimental study on direct thrust measurement. The thrust force generated by the repetitive detonation from a 50 mm inner diameter and 600 mm length tube was directly measured using load cell. Shchelkin spiral was used as an accelerator for the Deflagration to Detonation Transition (DDT) phenomenon. Propane-oxygen at stoichiometric condition was used as the combustible fuel-air mixture for the PDE. The PDE was operated at the operation frequency of 3Hz during the test. The amount of thrust force that was measured during the test reaching up to 70N. These values of thrust force were found to be fluctuating and its combustion phenomenon has been analyzed and discussed.

  6. Measurement by load cells of impact force which a human body receives by external force

    Directory of Open Access Journals (Sweden)

    Y. Ito

    2008-05-01

    Full Text Available Purpose: By development of a robotics technique, the assisted living instruments which have intelligent functions are being developed. As a result, there is a possibility that the accident to which the assisted living instrument under actuation contacts a human body may occur. The purpose of this research is for the impact force measurement system which with load cells to build, and to evaluate performance.Design/methodology/approach: The impact force measurement system was built by load cells and a data logger. Evaluation of the performance of the system was carried out to static loads and dynamic loads.Findings: By covering the sensor part of load cells with shock absorbing material, it turned out that it is possible to measure impact load simple. Moreover, as a result of comparing the characteristic of shock absorbing material, it became clear that the impact-absorbing characteristic of cell sponge and organism soft tissue is in agreement.Research limitations/implications: This research estimated the impact-absorbing characteristic of organism soft tissue for the skin, fat, muscles, etc. as a complex.Practical implications: This paper cleared that the load which a bone receives by dynamic external force can be easily measured by load cells.Originality/value: The objective of this research project was to develop the system by which impact force is measured and evaluated based on the damage which a human body receives. And we were able to complete the prototype.

  7. Bite by moray eel

    Directory of Open Access Journals (Sweden)

    JP Barreiros

    2008-01-01

    Full Text Available Injuries caused by moray eels are not a common problem, but are distributed throughout the globe, affecting mainly fishermen while manipulating hooked or netted fish. On a lesser scale, scuba divers and snorkelers, practicing or not spear fishing, are occasional victims of bites. With more than 185 species distributed among 15 genera, mostly in tropical to temperate shallow water, moray eels easily come into contact with humans and occasional injuries are not uncommon. The current study reports one case of moray eel bite and discusses the circumstances in which the accident happened, as well as wound evolution and therapy.

  8. Insect bite prevention.

    Science.gov (United States)

    Moore, Sarah J; Mordue Luntz, Anne Jennifer; Logan, James G

    2012-09-01

    Protection from the bites of arthropod (insect and acarine) vectors of disease is the first line of defense against disease transmission and should be advised in all cases when traveling abroad. Details are described of the main approaches for the prevention of bites, including topical or skin repellents, impregnated clothing, bed nets, and spatial or aerial repellents and aerosols. The bionomics of the main arthropod vectors of disease are described along with photographic plates and tabulated advice to give the traveler. An in-depth treatment of the different protection methodologies provides an up-to-date overview of the technologies involved. PMID:22963776

  9. Phoretic Force Measurement for Microparticles Under Microgravity Conditions

    Science.gov (United States)

    Davis, E. J.; Zheng, R.

    1999-01-01

    This theoretical and experimental investigation of the collisional interactions between gas molecules and solid and liquid surfaces of microparticles involves fundamental studies of the transfer of energy, mass and momentum between gas molecules and surfaces. The numerous applications include particle deposition on semiconductor surfaces and on surfaces in combustion processes, containerless processing, the production of nanophase materials, pigments and ceramic precursors, and pollution abatement technologies such as desulfurization of gaseous effluents from combustion processes. Of particular emphasis are the forces exerted on microparticles present in a nonuniform gas, that is, in gaseous surroundings involving temperature and concentration gradients. These so-called phoretic forces become the dominant forces when the gravitational force is diminished, and they are strongly dependent on the momentum transfer between gas molecules and the surface. The momentum transfer, in turn, depends on the gas and particle properties and the mean free path and kinetic energy of the gas molecules. The experimental program involves the particle levitation system shown. A micrometer size particle is held between two heat exchangers enclosed in a vacuum chamber by means of ac and dc electric fields. The ac field keeps the particle centered on the vertical axis of the chamber, and the dc field balances the gravitational force and the thermophoretic force. Some measurements of the thermophoretic force are presented in this paper.

  10. Força de mordida em crianças com mantenedor de espaço funcional na fase da dentadura mista inicial Bite force in children with functional space maintainer in early mixed dentition

    Directory of Open Access Journals (Sweden)

    Suzane Rodrigues Jacinto-Gonçalves

    2009-08-01

    Full Text Available OBJETIVO: verificar a influência do mantenedor de espaço funcional (MEF na força muscular em crianças com perda prematura de molares decíduos na fase inicial da dentadura mista (5,5 a 6,5 anos de idade com oclusão normal, considerando-se o padrão facial. MÉTODOS: a amostra foi constituída por dois grupos: Grupo MEF (n = 15, com perda precoce de pelo menos um molar decíduo; e Grupo Controle (n = 16. Determinou-se a força de mordida máxima (FM com um tubo transmissor pressurizado, conectado a um circuito eletrônico analógico/digital antes (t0, um mês (t1 e 6 meses (t6 após a instalação do mantenedor. O padrão facial foi determinado pelo índice de Jarabak (FHR. Os dados foram analisados pela estatística descritiva, análise de variância para medidas repetidas, teste t e correlação de Pearson. RESULTADOS:a FM foi significativamente menor em t0 e t1 para o Grupo MEF em relação ao Controle. Em t6 não houve diferença. Os dois grupos apresentaram a FM significativamente maior em t6, em relação a t0, mas o percentual de variação para o Grupo MEF foi significativamente maior. Os valores de FHR não se correlacionaram com a FM, não ocorrendo diferença entre os tipos faciais intragrupos. Os dolicofaciais do Grupo MEF apresentaram a FM significativamente menor que os do Grupo Controle, em t0 e t1, mas não em t6. CONCLUSÃO: o maior aumento na FM para o Grupo MEF após 6 meses foi favorecido pelo maior número de contatos oclusais, devido aos dentes artificiais, melhorando a função e recuperando a força muscular.AIM: To verify the influence of a functional space maintainer (FSM in muscle strength in children with premature loss of primary molars in early mixed dentition (5.5-6.5 years old with normal occlusion, considering the facial pattern. METHODS: The sample was distributed in: FSM Group (n = 15, with premature loss of at least one primary molar and a Control Group (n = 16. It was determined the maximal bite force (BF

  11. A Load Cell for the Measurement of Slack Mooring Forces

    Science.gov (United States)

    Balaji, R.; Sannasiraj, S. A.; Sundar, V.

    2014-07-01

    A load cell for the measurement of mooring forces is designed using the load-strain principles and the same is verified for its efficiency by structural modeling. A model load cell is fabricated and calibrated through laboratory experiments using three axes loading as well as mooring chain catenary principles. Experiments are also conducted in the physical wave tank to measure the mooring forces exerted on a disc shaped data buoy by using the designed load cell. The details of the design concepts, structural modeling, instrumentation, calibration, wave tank experiments and the results are discussed in this paper.

  12. Identification of GMS friction model without friction force measurement

    International Nuclear Information System (INIS)

    This paper deals with an online identification of the Generalized Maxwell Slip (GMS) friction model for both presliding and sliding regime at the same time. This identification is based on robust adaptive observer without friction force measurement. To apply the observer, a new approach of calculating the filtered friction force from the measurable signals is introduced. Moreover, two approximations are proposed to get the friction model linear over the unknown parameters and an approach of suitable filtering is introduced to guarantee the continuity of the model. Simulation results are presented to prove the efficiency of the approach of identification.

  13. Influence of Nanoscale Surface Roughness on Colloidal Force Measurements.

    Science.gov (United States)

    Zou, Yi; Jayasuriya, Sunil; Manke, Charles W; Mao, Guangzhao

    2015-09-29

    Forces between colloidal particles determine the performances of many industrial processes and products. Colloidal force measurements conducted between a colloidal particle AFM probe and particles immobilized on a flat substrate are valuable in selecting appropriate surfactants for colloidal stabilization. One of the features of inorganic fillers and extenders is the prevalence of rough surfaces-even the polymer latex particles, often used as model colloidal systems including the current study, have rough surfaces albeit at a much smaller scale. Surface roughness is frequently cited as the reason for disparity between experimental observations and theoretical treatment but seldom verified by direct evidence. This work reports the effect of nanoscale surface roughness on colloidal force measurements carried out in the presence of surfactants. We applied a heating method to reduce the mean surface roughness of commercial latex particles from 30 to 1 nm. We conducted force measurements using the two types of particles at various salt and surfactant concentrations. The surfactants used were pentaethylene glycol monododecyl ether, Pluronic F108, and a styrene/acrylic copolymer, Joncryl 60. In the absence of the surfactant, nanometer surface roughness affects colloidal forces only in high salt conditions when the Debye length becomes smaller than the surface roughness. The adhesion is stronger between colloids with higher surface roughness and requires a higher surfactant concentration to be eliminated. The effect of surface roughness on colloidal forces was also investigated as a function of the adsorbed surfactant layer structure characterized by AFM indentation and dynamic light scattering. We found that when the layer thickness exceeds the surface roughness, the colloidal adhesion is less influenced by surfactant concentration variation. This study demonstrates that surface roughness at the nanoscale can influence colloidal forces significantly and should be taken

  14. Systematic review of ground reaction force measurements in cats.

    Science.gov (United States)

    Schnabl, E; Bockstahler, B

    2015-10-01

    Although orthopaedic abnormalities in cats are frequently observed radiographically, they remain clinically underdiagnosed, and kinetic motion analysis, a fundamental aspect of orthopaedic research in dogs and horses, is not commonly performed. More information obtained with non-invasive measurement techniques to assess normal and abnormal gait in cats would provide a greater insight into their locomotion and biomechanics and improve the objective measurement of disease alterations and treatment modalities. In this systematic review, 12 previously performed studies that investigated ground reaction force measurements in cats during locomotion were evaluated. The aims of these studies, the measurement methods and equipment used, and the outcomes of parameters used to assess both sound and diseased cats are summarised and discussed. All reviewed studies used pressure sensitive walkways to gain data and all provided an acclimatisation period as a prerequisite for measurements. In sound cats during walking, the forelimb peak vertical force was greater than in the hindlimb and the peak vertical force in the hindlimb was greater in cats than in dogs. This review confirms that ground reaction forces can be used to evaluate lameness and treatment effects in the cat. PMID:26118478

  15. African tick bite fever

    DEFF Research Database (Denmark)

    Johansen, Jakob Aaquist; Thybo, Søren

    2011-01-01

    The incident of spotted fever imported to Denmark is unknown. We present a classic case of African Tick Bite Fever (ATBF) to highlight a disease, which frequently infects wildlife enthusiasts and hunters on vacation in South Africa. ATBF has a good prognosis and is easily treated with doxycyclin...

  16. Mosquito Bites are Bad!

    Centers for Disease Control (CDC) Podcasts

    2016-08-11

    In this podcast for kids, the Kidtastics talk about the dangers of mosquito bites and how to prevent getting them.  Created: 8/11/2016 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/11/2016.

  17. Force-Velocity Measurements of a Few Growing Actin Filaments

    Science.gov (United States)

    Brangbour, Coraline; du Roure, Olivia; Helfer, Emmanuèle; Démoulin, Damien; Mazurier, Alexis; Fermigier, Marc; Carlier, Marie-France; Bibette, Jérôme; Baudry, Jean

    2011-01-01

    The polymerization of actin in filaments generates forces that play a pivotal role in many cellular processes. We introduce a novel technique to determine the force-velocity relation when a few independent anchored filaments grow between magnetic colloidal particles. When a magnetic field is applied, the colloidal particles assemble into chains under controlled loading or spacing. As the filaments elongate, the beads separate, allowing the force-velocity curve to be precisely measured. In the widely accepted Brownian ratchet model, the transduced force is associated with the slowing down of the on-rate polymerization. Unexpectedly, in our experiments, filaments are shown to grow at the same rate as when they are free in solution. However, as they elongate, filaments are more confined in the interspace between beads. Higher repulsive forces result from this higher confinement, which is associated with a lower entropy. In this mechanism, the production of force is not controlled by the polymerization rate, but is a consequence of the restriction of filaments' orientational fluctuations at their attachment point. PMID:21541364

  18. Force-velocity measurements of a few growing actin filaments.

    Directory of Open Access Journals (Sweden)

    Coraline Brangbour

    2011-04-01

    Full Text Available The polymerization of actin in filaments generates forces that play a pivotal role in many cellular processes. We introduce a novel technique to determine the force-velocity relation when a few independent anchored filaments grow between magnetic colloidal particles. When a magnetic field is applied, the colloidal particles assemble into chains under controlled loading or spacing. As the filaments elongate, the beads separate, allowing the force-velocity curve to be precisely measured. In the widely accepted Brownian ratchet model, the transduced force is associated with the slowing down of the on-rate polymerization. Unexpectedly, in our experiments, filaments are shown to grow at the same rate as when they are free in solution. However, as they elongate, filaments are more confined in the interspace between beads. Higher repulsive forces result from this higher confinement, which is associated with a lower entropy. In this mechanism, the production of force is not controlled by the polymerization rate, but is a consequence of the restriction of filaments' orientational fluctuations at their attachment point.

  19. Enclosed Electronic System for Force Measurements in Knee Implants

    Directory of Open Access Journals (Sweden)

    David Forchelet

    2014-08-01

    Full Text Available Total knee arthroplasty is a widely performed surgical technique. Soft tissue force balancing during the operation relies strongly on the experience of the surgeon in equilibrating tension in the collateral ligaments. Little information on the forces in the implanted prosthesis is available during surgery and post-operative treatment. This paper presents the design, fabrication and testing of an instrumented insert performing force measurements in a knee prosthesis. The insert contains a closed structure composed of printed circuit boards and incorporates a microfabricated polyimide thin-film piezoresistive strain sensor for each condylar compartment. The sensor is tested in a mechanical knee simulator that mimics in-vivo conditions. For characterization purposes, static and dynamic load patterns are applied to the instrumented insert. Results show that the sensors are able to measure forces up to 1.5 times body weight with a sensitivity fitting the requirements for the proposed use. Dynamic testing of the insert shows a good tracking of slow and fast changing forces in the knee prosthesis by the sensors.

  20. Measurement of Large Forces and Deflections in Microstructures

    CERN Document Server

    Hals, Kai Axel; Chen, Xuyuan

    2008-01-01

    Properties of typical MEMS materials have been widely investigated. Mechanical properties of MEMS structures depend not only on the bulk material properties, but also structural factors. A measurement system has been made to measure force/deflection on microstructures to examine some of the structural properties. This is a stylus setup integrated with a load cell and a linear actuator. First, the requirements for the measurement system were established. Then the system was built up and characterized. We have successfully made measurements on a typical micromechanical structure, a cantilever accelerometer design. The stylus placement accuracy, the spring constant along the proof mass, analysis of the force/deflection curve shape and destructive tests on the cantilever have been investigated in our experiment and will be presented in this paper.

  1. Laser measurement method of forced vibration in optical systems

    International Nuclear Information System (INIS)

    A forced vibration measurement method by laser combining the laser signal and high frequency CCD in optical systems is introduced. The method solves the conversion problem between the vibration signal and laser signal in optical systems, which can not only measure the impact of vibration on the beam stability, but also acquire the frequency characteristics of vibration signals. Forced vibration in an optical system is measured when the frequencies of vibration signals are 150 Hz and 200 Hz by using the method and the attributes of the vibration signals obtained fits those of the input signals. Test and analysis results demonstrate that the method has a time amplitude uncertainty of 6.25 μm and frequency resolution of 2 Hz. The handy and efficient method, whose measurement is precise, has been applied to the beam pointing stability study of the multiplexing excimer MOPA laser targeting test platform accordingly. (authors)

  2. Effect of permanent-magnet irregularities in levitation force measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Hull, J. R.

    1999-10-14

    In the measurement of the levitation force between a vertically magnetized permanent magnet (PM) and a bulk high-temperature superconductor (HTS), PM domains with horizontal components of magnetization are shown to produce a nonnegligible contribution to the levitation force in most systems. Such domains are typically found in all PMs, even in those that exhibit zero net horizontal magnetic moment. Extension of this analysis leads to an HTS analog of Earnshaw's theorem, in which at the field-cooling position the vertical stiffness is equal to the sum of the horizontal stiffnesses, independent of angular distribution of magnetic moments within the PM.

  3. Aerodynamics of Dragonfly in Hover: Force measurements and PIV results

    Science.gov (United States)

    Deng, Xinyan; Hu, Zheng

    2009-11-01

    We useda pair of dynamically scaled robotic dragonfly model wings to investigate the aerodynamic effects of wing-wing interaction in dragonflies. We follow the wing kinematics of real dragonflies in hover, while systematically varied the phase difference between the forewing and hindwing. Instantaneous aerodynamic forces and torques were measured on both wings, while flow visualization and PIV results were obtained. The results show that, in hovering flight, wing-wing interaction causes force reduction for both wings at most of the phase angle differences except around 0 degree (when the wings are beating in-phase).

  4. Profile of Dog Bite Cases in an Urban Area of Kolkata, India

    Directory of Open Access Journals (Sweden)

    Ayan Ghosh, Ranabir Pal

    2014-01-01

    Results: In the present study of the reported animal bite cases affected all the ages and both genders; the incidence of animal bites decreased with increasing age. Majority of the victims were males except in elderly population; children were more vulnerable. Two thirds of animal bite victims were from socioeconomic class IV and V. Dogs were the most common biting animal followed by Cats. Maximum number of study participants reported to health centre within 24 to 48 hours and very few cases within 24 hours after bite. Late reported cases, especially after 5 days, constituted by younger children or illiterate elderly people were forcefully brought to the hospital by their family members or caregivers. Conclusions:Dog bite is common in males and children less than ten years among our study population with more of third degree bites though health seeking behaviour is far from expectation.

  5. An appraisal of techniques and equipment for cutting force measurement

    Institute of Scientific and Technical Information of China (English)

    AUDY J.

    2006-01-01

    Current research focussed on the assessment of metal machining process parameters and on the development of adaptive control, shows that machine performance, work-piece and tool material selections, tool life, quality of machined surfaces,the geometry of cutting tool edges, and cutting conditions are closely related to the cutting forces. This information is of great interest to cutting tool manufactures and users alike. Over the years there have been significant developments and improvements in the equipment used to monitor such forces. In 1930 mechanical gauges were replaced by resistance strain gauges, and some 30 years later compact air gauge dynamometers were invented. Since this time intensive research has continued being directed towards developing new approaches to cutting force measurement. The Kistler Company, well-known manufacturer of acceleration and piezoelectrical dynamometers, has worked in this field for more than three decades, and developed very sensitive devices.While leading manufacturing research laboratories are often equipped with this technology, classical electrical strain gauges and other dynamometers of individual designs are still commonly used in industry. The present paper presents data obtained using different techniques of force measurement in metal machining processes. In particular, areas of uncertainties, illustrated through results concerning the turning process, are analysed, leading to an appraisal of the current status of these measurements and their significance.

  6. Measurement of the absolute separation for atomic force microscopy measurements in the presence of adsorbed polymer

    OpenAIRE

    McKee, C. T.; Mosse, W. K. J.; Ducker, W. A.

    2006-01-01

    We demonstrate that the absolute separation between an atomic force microscope (AFM) tip and a solid substrate can be measured in the presence of an irreversibly adsorbed polymer film. The separation is obtained from the analysis of a scattered evanescent wave that is generated at the surface of the solid. By comparing our scattering measurements to conventional AFM measurements, we also show an example where a conventional AFM measurement gives the incorrect force-distance profile. We valida...

  7. Photothermally excited force modulation microscopy for broadband nanomechanical property measurements

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Ryan, E-mail: ryan.wagner@nist.gov; Killgore, Jason P. [Material Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2015-11-16

    We demonstrate photothermally excited force modulation microscopy (PTE FMM) for mechanical property characterization across a broad frequency range with an atomic force microscope (AFM). Photothermal excitation allows for an AFM cantilever driving force that varies smoothly as a function of drive frequency, thus avoiding the problem of spurious resonant vibrations that hinder piezoelectric excitation schemes. A complication of PTE FMM is that the sub-resonance cantilever vibration shape is fundamentally different compared to piezoelectric excitation. By directly measuring the vibrational shape of the cantilever, we show that PTE FMM is an accurate nanomechanical characterization method. PTE FMM is a pathway towards the characterization of frequency sensitive specimens such as polymers and biomaterials with frequency range limited only by the resonance frequency of the cantilever and the low frequency limit of the AFM.

  8. Measuring Industry Coagglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Newman, Carol; Tarp, Finn

    2015-01-01

    examine what this index reveals about the importance of transport costs, labour market pooling and technology transfer for agglomeration processes, controlling for overall industry agglomeration. We compare the results based on our new measure to existing measures in the literature and find very different......Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We construct a new coagglomeration index based purely on the location of firms. We...

  9. Bounds on fifth forces from precision measurements on molecules

    CERN Document Server

    Salumbides, E J; Komasa, J; Pachucki, K; Eikema, K S E; Ubachs, W

    2013-01-01

    Highly accurate results from frequency measurements on neutral hydrogen molecules H_2, HD and D_2 as well as the HD^+ ion can be interpreted in terms of constraints on possible fifth-force interactions. Where the hydrogen atom is a probe for yet unknown lepton-hadron interactions, and the helium atom is sensitive for lepton-lepton interactions, molecules open the domain to search for additional long-range hadron-hadron forces. First principles calculations in the framework of quantum electrodynamics have now advanced to the level that hydrogen molecules and hydrogen molecular ions have become calculable systems, making them a search-ground for fifth forces. Following a phenomenological treatment of unknown hadron-hadron interactions written in terms of a Yukawa potential of the form V_5(r)=\\beta exp(-r/\\lambda)/r current precision measurements on hydrogenic molecules yield a constraint \\beta < 1 \\times 10^{-7} eV\\AA for long-range hadron-hadron interactions at typical force ranges commensurate with separat...

  10. Novel parallel plate condenser for single particle electrostatic force measurements in atomic force microscope

    KAUST Repository

    Kwek, Jin Wang

    2011-07-01

    A combination of small parallel plate condenser with Indium Tin Oxide (ITO) glass slides as electrodes and an atomic force microscope (AFM) is used to characterize the electrostatic behavior of single glass bead microparticles (105-150 μm) glued to the AFM cantilever. This novel setup allows measurements of the electrostatic forces acting on a particle in an applied electrical field to be performed in ambient air conditions. By varying the position of the microparticle between the electrodes and the strength of the applied electric field, the relative contributions of the particle net charge, induced and image charges were investigated. When the microparticle is positioned in the middle of the electrodes, the force acting on the microparticle was linear with the applied electric field and proportional to the microparticle net charge. At distances close to the bottom electrode, the force follows a parabolic relationship with the applied electric field reflecting the contributions of induced and image charges. The method can be used for the rapid evaluation of the charging and polarizability properties of the microparticle as well as an alternative to the conventional Faraday\\'s pail technique. © 2011 Elsevier B.V.

  11. Direct force measurement of single DNA-peptide interactions using atomic force microscopy.

    Science.gov (United States)

    Chung, Ji W; Shin, Dongjin; Kwak, June M; Seog, Joonil

    2013-06-01

    The selective interactions between DNA and miniature (39 residues) engineered peptide were directly measured at the single-molecule level by using atomic force microscopy. This peptide (p007) contains an α-helical recognition site similar to leucine zipper GCN4 and specifically recognizes the ATGAC sequence in the DNA with nanomolar affinity. The average rupture force was 42.1 pN, which is similar to the unbinding forces of the digoxigenin-antidigoxigenin complex, one of the strongest interactions in biological systems. The single linear fit of the rupture forces versus the logarithm of pulling rates showed a single energy barrier with a transition state located at 0.74 nm from the bound state. The smaller koff compared with that of other similar systems was presumably due to the increased stability of the helical structure by putative folding residues in p007. This strong sequence-specific DNA-peptide interaction has a potential to be utilized to prepare well-defined mechanically stable DNA-protein hybrid nanostructures.

  12. Diamagnetic Levitation Cantilever System for the Calibration of Normal Force Atomic Force Microscopy Measurements

    Science.gov (United States)

    Torres, Jahn; Yi, Jin-Woo; Murphy, Colin; Kim, Kyung-Suk

    2011-03-01

    In this presentation we report a novel technique for normal force calibration for Atomic Force Microcopy (AFM) adhesion measurements known as the diamagnetic normal force calibration (D-NFC) system. The levitation produced by the repulsion between a diamagnetic graphite sheet and a set of rare-earth magnets is used in order to produce an oscillation due to an unstable mechanical moment produced by a silicon cantilever supported on the graphite. The measurement of the natural frequency of this oscillation allows for the calculation of the stiffness of the system to three-digit accuracy. The D-NFC response was proven to have a high sensitivity for the structure of water molecules collected on its surface. This in turns allows for the study of the effects of coatings on the structure of surface water. This work was supported by the Coatings/Biofouling Program and the Maritime Sensing Program of the Office of Naval Research as well as the ILIR Program of the Naval Undersea Warfare Center DIVNPT.

  13. Measurements of planing forces and cavity shapes on cylindrical afterbodies

    Science.gov (United States)

    Hellum, Aren; Belden, Jesse; Beal, David; Huyer, Stephen; Henoch, Charles; Hrubes, Dana

    2015-11-01

    Supercavitation is a drag reduction technique by which an underwater body is enclosed over a significant portion of its length in a bubble of gas. Hydrodynamic forces act on the body only through contact with the nose and a planing section at the rear. Models of the planing forces typically assume that the body is placed into a cavity which is unchanged by the presence of the body, and the present study was designed to test the validity of this assumption. Measurements were taken of the planing forces for five afterbody lengths over a range of angles concurrently with photographs showing the size and shape of the cavity produced. These observations reveal that the cavity form and growth rate are significantly affected by both the length and angle of attack of the body; the length of the cavity shrinks at the same angle of attack as the body length is reduced past a critical threshold, suggesting a hydrodynamic interaction between the afterbody trailing edge and the cavity. Additionally, the planing forces demonstrate a non-monotonic dependence on attack angle that is not readily explained by existing models, specifically a ``lift crisis'' for short bodies in which the planing lift goes to zero over a range from -1 to -3 degrees.

  14. Food aroma affects bite size

    Directory of Open Access Journals (Sweden)

    de Wijk René A

    2012-03-01

    Full Text Available Abstract Background To evaluate the effect of food aroma on bite size, a semisolid vanilla custard dessert was delivered repeatedly into the mouth of test subjects using a pump while various concentrations of cream aroma were presented retronasally to the nose. Termination of the pump, which determined bite size, was controlled by the subject via a push button. Over 30 trials with 10 subjects, the custard was presented randomly either without an aroma, or with aromas presented below or near the detection threshold. Results Results for ten subjects (four females and six males, aged between 26 and 50 years, indicated that aroma intensity affected the size of the corresponding bite as well as that of subsequent bites. Higher aroma intensities resulted in significantly smaller sizes. Conclusions These results suggest that bite size control during eating is a highly dynamic process affected by the sensations experienced during the current and previous bites.

  15. Thermophoretic force measurements of spherical and non-spherical particles

    Science.gov (United States)

    Zheng, Feng

    An electrodynamic balance (EDB) with three-dimensional force compensation and measurement ability was developed for single particle thermophoretic force measurements. The new EDB had an octopole double-ring electrode. Each electrode ring was split into four equal segments. Different voltages were applied to each segment so that three independent and orthogonal dc fields were superimposed on another ac electric field. The balance constants of the new EDB were determined by both numerical calculations and measurements. Among the various particle size measurement techniques, the oscillation offset method was found to be an accurate and universal method for particle size determination with an EDB. The technique involved partially balancing the gravitational force on a particle to let it oscillate stably in the ac electric field. The oscillation trajectory was recorded using a linescan camera, and the data were fitted to the solution for the particle equation of motion to obtain its size. For aggregate particles of single, two and three polystyrene latex (PSL) spheres (nominal diameter 19.7 mum), the equivalent volume diameters were determined by the oscillation offset method within 3%. The thermophoretic force on these PSL sphere aggregates, with their plane of centers parallel to the temperature gradient, was measured using the octopole double-ring EDB. Thermophoretic force (TF) shape factor kT was defined as the ratio of the TF on a particle of interest to that on a sphere of equal volume. For PSL doublets kT is 1.13 +/- 0.08 at Kn = 0.98 in nitrogen and 1.04 +/- 0.03 at Kn = 0.65 in helium. For PSL triangular triplets kT is 1.20 +/- 0.12 at Kn = 0.98 in nitrogen, and 1.06 +/- 0.06 at Kn = 0.65 in helium. The TF shape factors compare fairly well with the continuum limits predicted by the existing theories. It was found that the TF shape factor only depends on the Knudsen number weakly in the transition regime. The TF shape factor was found to increase with the number

  16. Single Molecule Force Measurement for Protein Synthesis on the Ribosome

    Science.gov (United States)

    Uemura, Sotaro

    2008-04-01

    The ribosome is a molecular machine that translates the genetic code described on the messenger RNA (mRNA) into an amino acid sequence through repetitive cycles of transfer RNA (tRNA) selection, peptide bond formation and translocation. Although the detailed interactions between the translation components have been revealed by extensive structural and biochemical studies, it is not known how the precise regulation of macromolecular movements required at each stage of translation is achieved. Here we demonstrate an optical tweezer assay to measure the rupture force between a single ribosome complex and mRNA. The rupture force was compared between ribosome complexes assembled on an mRNA with and without a strong Shine-Dalgarno (SD) sequence. The removal of the SD sequence significantly reduced the rupture force, indicating that the SD interactions contribute significantly to the stability of the ribosomal complex on the mRNA in a pre-peptidyl transfer state. In contrast, the post-peptidyl transfer state weakened the rupture force as compared to the complex in a pre-peptidyl transfer state and it was the same for both the SD-containing and SD-deficient mRNAs. The results suggest that formation of the first peptide bond destabilizes the SD interaction, resulting in the weakening of the force with which the ribosome grips an mRNA. This might be an important requirement to facilitate movement of the ribosome along mRNA during the first translocation step. In this article, we discuss about the above new results including the introduction of the ribosome translation mechanism and the optical tweezer method.

  17. DIRECT MEASUREMENT OF WEAK DEPLETION FORCE BETWEEN TWO SURFACES*

    Institute of Scientific and Technical Information of China (English)

    Xiang-jun Gong; Xiao-chen Xing; Xiao-ling Wei; To Ngai

    2011-01-01

    In a mixture of colloidal particles and polymer molecules, the particles may experience an attractive “depletion force” if the size of the polymer molecule is larger than the interparticle separation. This is because individual polymer molecules experience less conformational entropy if they stay between the particles than they escape the inter-particle space,which results in an osmotic pressure imbalance inside and outside the gap and leads to interparticle attraction. This depletion force has been the subject of several studies since the 1980s, but the direct measurement of this force is still experimentally challenging as it requires the detection of energy variations of the order of kBT and beyond. We present here our results for applying total internal reflection microscopy (TIRM) to directly measure the interaction between a free-moving particle and a flat surface in solutions consisting of small water-soluble organic molecules or polymeric surfactants. Our results indicate that stable nanobubbles (ca. 150 nm) exist free in the above aqueous solutions. More importantly, the existence of such nanobubbles induces an attraction between the spherical particle and flat surface. Using TIRM, we are able to directly measure such weak interaction with a range up to 100 nm. Furthermore, we demonstrate that by employing thermo-sensitive microgel particles as a depleting agent, we are able to quantitatively measure and reversibly control kBT-scale depletion attraction as function of solution pH.

  18. Interlaboratory comparison of traceable atomic force microscope pitch measurements

    Science.gov (United States)

    Dixson, Ronald; Chernoff, Donald A.; Wang, Shihua; Vorburger, Theodore V.; Tan, Siew Leng; Orji, Ndubuisi G.; Fu, Joseph

    2010-06-01

    The National Institute of Standards and Technology (NIST), Advanced Surface Microscopy (ASM), and the National Metrology Centre (NMC) of the Agency for Science, Technology, and Research (A*STAR) in Singapore have completed a three-way interlaboratory comparison of traceable pitch measurements using atomic force microscopy (AFM). The specimen being used for this comparison is provided by ASM and consists of SiO2 lines having a 70 nm pitch patterned on a silicon substrate. NIST has a multifaceted program in atomic force microscope (AFM) dimensional metrology. One component of this effort is a custom in-house metrology AFM, called the calibrated AFM (C-AFM). The NIST C-AFM has displacement metrology for all three axes traceable to the 633 nm wavelength of the iodine-stabilized He-Ne laser - a recommended wavelength for realization of the SI (Système International d'Unités, or International System of Units) meter. NIST used the C-AFM to participate in this comparison. ASM used a commercially available AFM with an open-loop scanner, calibrated by a 144 nm pitch transfer standard. In a prior collaboration with Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, ASM's transfer standard was calibrated using PTB's traceable optical diffractometry instrument. Thus, ASM's measurements are also traceable to the SI meter. NMC/A*STAR used a large scanning range metrological atomic force microscope (LRM-AFM). The LRM-AFM integrates an AFM scanning head into a nano-stage equipped with three built-in He-Ne laser interferometers so that its measurement related to the motion on all three axes is directly traceable to the SI meter. The measurements for this interlaboratory comparison have been completed and the results are in agreement within their expanded uncertainties and at the level of a few parts in 104.

  19. Esthetic correction in open bite

    Directory of Open Access Journals (Sweden)

    Swapnil Parlani

    2011-01-01

    Full Text Available Deleterious oral habits, which are persistent, can lead to poor esthetics of a beautiful face. Conventional treatment modalities for an open bite usually include orthodontic treatment and/or skeletal surgery. This article focuses on a different treatment modality for an anterior open bite.

  20. Animal Bites of the Hand

    Science.gov (United States)

    ... history of the bite, including the type of animal and its health (behavior and rabies vaccine status), the time and location of the event, circumstances of the bite, whereabouts of the animal, and the pre-hospital treatment will be reviewed. ...

  1. Fundamental aspects of electric double layer force-distance measurements at liquid-solid interfaces using atomic force microscopy

    Science.gov (United States)

    Black, Jennifer M.; Zhu, Mengyang; Zhang, Pengfei; Unocic, Raymond R.; Guo, Daqiang; Okatan, M. Baris; Dai, Sheng; Cummings, Peter T.; Kalinin, Sergei V.; Feng, Guang; Balke, Nina

    2016-09-01

    Atomic force microscopy (AFM) force-distance measurements are used to investigate the layered ion structure of Ionic Liquids (ILs) at the mica surface. The effects of various tip properties on the measured force profiles are examined and reveal that the measured ion position is independent of tip properties, while the tip radius affects the forces required to break through the ion layers as well as the adhesion force. Force data is collected for different ILs and directly compared with interfacial ion density profiles predicted by molecular dynamics. Through this comparison it is concluded that AFM force measurements are sensitive to the position of the ion with the larger volume and mass, suggesting that ion selectivity in force-distance measurements are related to excluded volume effects and not to electrostatic or chemical interactions between ions and AFM tip. The comparison also revealed that at distances greater than 1 nm the system maintains overall electroneutrality between the AFM tip and sample, while at smaller distances other forces (e.g., van der waals interactions) dominate and electroneutrality is no longer maintained.

  2. Fundamental aspects of electric double layer force-distance measurements at liquid-solid interfaces using atomic force microscopy

    Science.gov (United States)

    Black, Jennifer M.; Zhu, Mengyang; Zhang, Pengfei; Unocic, Raymond R.; Guo, Daqiang; Okatan, M. Baris; Dai, Sheng; Cummings, Peter T.; Kalinin, Sergei V.; Feng, Guang; Balke, Nina

    2016-01-01

    Atomic force microscopy (AFM) force-distance measurements are used to investigate the layered ion structure of Ionic Liquids (ILs) at the mica surface. The effects of various tip properties on the measured force profiles are examined and reveal that the measured ion position is independent of tip properties, while the tip radius affects the forces required to break through the ion layers as well as the adhesion force. Force data is collected for different ILs and directly compared with interfacial ion density profiles predicted by molecular dynamics. Through this comparison it is concluded that AFM force measurements are sensitive to the position of the ion with the larger volume and mass, suggesting that ion selectivity in force-distance measurements are related to excluded volume effects and not to electrostatic or chemical interactions between ions and AFM tip. The comparison also revealed that at distances greater than 1 nm the system maintains overall electroneutrality between the AFM tip and sample, while at smaller distances other forces (e.g., van der waals interactions) dominate and electroneutrality is no longer maintained. PMID:27587276

  3. Homicidal Snake Bite in Children.

    Science.gov (United States)

    Paulis, Melad G; Faheem, Ayman L

    2016-03-01

    Snake bites are common in many regions of the world. Snake envenomation is relatively uncommon in Egypt; such unfortunate events usually attract much publicity. Snake bite is almost only accidental, occurring in urban areas and desert. Few cases were reported to commit suicide by snake. Homicidal snake poisoning is so rare. It was known in ancient world by executing capital punishment by throwing the victim into a pit full of snakes. Another way was to ask the victim to put his hand inside a small basket harboring a deadly snake. Killing a victim by direct snake bite is so rare. There was one reported case where an old couple was killed by snake bite. Here is the first reported case of killing three children by snake bite. It appeared that the diagnosis of such cases is so difficult and depended mainly on the circumstantial evidences. PMID:27404632

  4. A voice coil motor based measuring force control system for tactile scanning profiler

    Science.gov (United States)

    Feng, Shengdong; Liu, Xiaojun; Chen, Liangzhou; Zhou, Liping; Lu, Wenlong

    2015-02-01

    In tactile scanning profiler, the measuring force would change in a wide range when it was used for profile measurement in a large range, which could possibly destroy the measured surface. To solve the problem, measuring force control system for tactile scanning profiler was needed. In the paper, a voice coil motor-based measuring force control system for tactile scanning profiler was designed. In the design, a low stiffness coefficient spring was used to provide contact force, while a voice coil motor (VCM) to balance the spring force so that the contact force could be kept for constant measuring force. A VCM was designed specially, and for active measuring force control, a precision current source circuit under the control of a DSP unit was designed to drive the VCM. The performance of voice coil motor based measuring force control system had been tested, and its good characteristics were verified.

  5. New facets of nuclear forces. Three-nucleon forces and precise measurements

    International Nuclear Information System (INIS)

    One of the main interests in nuclear physics is understanding the forces acting nuclear constituents. In the past decade substantial progress was made in descriptions of various phenomena of nuclei, by explicitly taking into account nucleon-nucleon forces. The results of comparison to the experimental data for binding energies of nuclei, equation of state of nuclear matter and three-nucleon scattering, strongly indicate the importance of 3NFs acting in systems with more than two nucleons. Nucleon-deuteron scattering, for which a rigorous formulation in terms of Faddeev equations exists and exact solutions of these equations for any dynamical input can be obtained, offers a good opportunity to study the dynamical aspects of 3NFs, such as momentum, spin, and/or iso-spin dependences. Since the first indication of 3NF effects in Nd elastic scattering around 100 MeV/nucleon precise measurements of proton-deuteron/neutron-deuteron elastic scattering have been extensively performed at 65-400 MeV/nucleon. Direct comparison between the data and the Faddeev calculations draws the following conclusions, (1) the 3NF is definitely needed in Nd elastic scattering, (2) the spin dependent parts of the 3NF are deficient, (3) the short-range components of the 3NF are probably required for high momentum transfer region. (author)

  6. A verification of quantum field theory – measurement of Casimir force

    Indian Academy of Sciences (India)

    Anushree Roy; U Mohideen

    2001-02-01

    Here we review our work on measurement of the Casimir force between a large aluminum coated a sphere and flat plate using an atomic force microscope. The average statistical precision is 1% of the force measured at the closest separation. We have also shown nontrival boundary dependence of the Casimir force.

  7. Kelvin probe force microscopy of metallic surfaces used in Casimir force measurements

    Science.gov (United States)

    Behunin, R. O.; Dalvit, D. A. R.; Decca, R. S.; Genet, C.; Jung, I. W.; Lambrecht, A.; Liscio, A.; López, D.; Reynaud, S.; Schnoering, G.; Voisin, G.; Zeng, Y.

    2014-12-01

    Kelvin probe force microscopy at normal pressure was performed by two different groups on the same Au-coated planar sample used to measure the Casimir interaction in a sphere-plane geometry. The obtained voltage distribution was used to calculate the separation dependence of the electrostatic pressure Pres(D ) in the configuration of the Casimir experiments. In the calculation it was assumed that the potential distribution in the sphere has the same statistical properties as the measured one, and that there are no correlation effects on the potential distributions due to the presence of the other surface. The result of this calculation, using the currently available knowledge, is that Pres(D ) does not explain the magnitude or the separation dependence of the difference Δ P (D ) between the measured Casimir pressure and the one calculated using a Drude model for the electromagnetic response of Au. We discuss in the conclusions the points which have to be checked out by future work, including the influence of pressure and a more accurate determination of the patch distribution, in order to confirm these results.

  8. Force measuring optical tweezers system for long time measurements of P pili stability

    Science.gov (United States)

    Andersson, Magnus; Fällman, Erik; Uhlin, Bernt Eric; Axner, Ove

    2006-02-01

    A force-measuring optical tweezers instrumentation and long time measurements of the elongation and retraction of bacterial fimbriae from Uropathogenic E. coli (UPEC) under strain are presented. The instrumentation is presented in some detail. Special emphasis is given to measures taken to reduce the influence of noise and drifts in the system and from the surrounding, which makes long term force measurements possible. Individual P pili from UPEC bacteria were used as a biological model system for repetitive unfolding and refolding cycles of bacterial fimbriae under equilibrium conditions. P pili have evolved into a three-dimensional helix-like structure, the PapA rod, that can be successively and significantly elongated and/or unfolded when exposed to external forces. The instrumentation is used for characterization of the force-vs.-elongation response of the PapA rod of individual P pili, with emphasis on the long time stability of the forced unfolding and refolding of the helical structure of the PapA rod. The results show that the PapA rod is capable of withstanding extensive strain, leading to a complete unfolding of the helical structure, repetitive times during the life cycle of a bacterium without any noticeable alteration of the mechanical properties of the P pili. This function is believed to be importance for UPEC bacteria in vivo since it provides a close contact to a host cell (which is an initial step of invasion) despite urine cleaning attempts.

  9. Influence of scanning force microscope loading force on measurement of ion—track diameter

    Institute of Scientific and Technical Information of China (English)

    WangYu-Gang; AckermannJ; 等

    1997-01-01

    Scanning force microscope(SFM) was operated in the lateral-force mode with different loading forces.The mica samples were irradiated by Se ions with a kinetic energy of 11.4MeV/u.The"full-height width" and the "half-height width" of track profiles were used to evaluate the ion-track diameter,For the former method,the average track diameter increases slowly with increasing loading force between SFM tip and sample.For the later method,the average diameters of ion track nearly keep a common value as the SFM loading force increases.

  10. Influence of atomic force microscope (AFM) probe shape on adhesion force measured in humidity environment

    Institute of Scientific and Technical Information of China (English)

    阳丽; 涂育松; 谭惠丽

    2014-01-01

    In micro-manipulation, the adhesion force has very important influence on behaviors of micro-objects. Here, a theoretical study on the effects of humidity on the adhesion force is presented between atomic force microscope (AFM) tips and substrate. The analysis shows that the precise tip geometry plays a critical role on humidity depen-dence of the adhesion force, which is the dominant factor in manipulating micro-objects in AFM experiments. For a blunt (paraboloid) tip, the adhesion force versus humidity curves tends to the apparent contrast (peak-to-valley corrugation) with a broad range. This paper demonstrates that the abrupt change of the adhesion force has high correla-tion with probe curvatures, which is mediated by coordinates of solid-liquid-vapor contact lines (triple point) on the probe profiles. The study provides insights for further under-standing nanoscale adhesion forces and the way to choose probe shapes in manipulating micro-objects in AFM experiments.

  11. Directly measuring single molecule heterogeneity using force spectroscopy

    CERN Document Server

    Hinczewski, Michael; Thirumalai, D

    2016-01-01

    One of the most intriguing results of single molecule experiments on proteins and nucleic acids is the discovery of functional heterogeneity: the observation that complex cellular machines exhibit multiple, biologically active conformations. The structural differences between these conformations may be subtle, but each distinct state can be remarkably long-lived, with random interconversions between states occurring only at macroscopic timescales, fractions of a second or longer. Though we now have proof of functional heterogeneity in a handful of systems---enzymes, motors, adhesion complexes---identifying and measuring it remains a formidable challenge. Here we show that evidence of this phenomenon is more widespread than previously known, encoded in data collected from some of the most well-established single molecule techniques: AFM or optical tweezer pulling experiments. We present a theoretical procedure for analyzing distributions of rupture/unfolding forces recorded at different pulling speeds. This re...

  12. Sensor Prototype to Evaluate the Contact Force in Measuring with Coordinate Measuring Arms

    Directory of Open Access Journals (Sweden)

    Eduardo Cuesta

    2015-06-01

    Full Text Available This paper describes the design, development and evaluation tests of an integrated force sensor prototype for portable Coordinate Measuring Arms (CMAs or AACMMs. The development is based on the use of strain gauges located on the surface of the CMAs’ hard probe. The strain gauges as well as their cables and connectors have been protected with a custom case, made by Additive Manufacturing techniques (Polyjet 3D. The same method has been selected to manufacture an ergonomic handle that includes trigger mechanics and the electronic components required for synchronizing the trigger signal when probing occurs. The paper also describes the monitoring software that reads the signals in real time, the calibration procedure of the prototype and the validation tests oriented towards increasing knowledge of the forces employed in manual probing. Several experiments read and record the force in real time comparing different ways of probing (discontinuous and continuous contact and measuring different types of geometric features, from single planes to exterior cylinders, cones, or spheres, through interior features. The probing force is separated into two components allowing the influence of these strategies in probe deformation to be known. The final goal of this research is to improve the probing technique, for example by using an operator training programme, allowing extra-force peaks and bad contacts to be minimized or just to avoid bad measurements.

  13. A technique for conditioning and calibrating force-sensing resistors for repeatable and reliable measurement of compressive force.

    Science.gov (United States)

    Hall, Rick S; Desmoulin, Geoffrey T; Milner, Theodore E

    2008-12-01

    Miniature sensors that could measure forces applied by the fingers and hand without interfering with manual dexterity or range of motion would have considerable practical value in ergonomics and rehabilitation. In this study, techniques have been developed to use inexpensive pressure-sensing resistors (FSRs) to accurately measure compression force. The FSRs are converted from pressure-sensing to force-sensing devices. The effects of nonlinear response properties and dependence on loading history are compensated by signal conditioning and calibration. A fourth-order polynomial relating the applied force to the current voltage output and a linearly weighted sum of prior outputs corrects for sensor hysteresis and drift. It was found that prolonged (>20h) shear force loading caused sensor gain to change by approximately 100%. Shear loading also had the effect of eliminating shear force effects on sensor output, albeit only in the direction of shear loading. By applying prolonged shear loading in two orthogonal directions, the sensors were converted into pure compression sensors. Such preloading of the sensor is, therefore, required prior to calibration. The error in compression force after prolonged shear loading and calibration was consistently industrial design applications where measurements of finger and hand force are needed.

  14. Development of a shear measurement sensor for measuring forces at human-machine interfaces.

    Science.gov (United States)

    Cho, Young Kuen; Kim, Seong Guk; Kim, Donghyun; Kim, Hyung Joo; Ryu, Jeicheong; Lim, Dohyung; Ko, Chang-Yong; Kim, Han Sung

    2014-12-01

    Measuring shear force is crucial for investigating the pathology and treatment of pressure ulcers. In this study, we introduced a bi-axial shear transducer based on strain gauges as a new shear sensor. The sensor consisted of aluminum and polyvinyl chloride plates placed between quadrangular aluminum plates. On the middle plate, two strain gauges were placed orthogonal to one another. The shear sensor (54 mm × 54 mm × 4.1 mm), which was validated by using standard weights, displayed high accuracy and precision (measurement range, -50 to 50 N; sensitivity, 0.3N; linear relationship, R(2)=0.9625; crosstalk error, 0.635% ± 0.031%; equipment variation, 4.183). The shear force on the interface between the human body and a stand-up wheelchair was measured during sitting or standing movements, using two mats (44.8 cm × 44.8 cm per mat) that consisted of 24 shear sensors. Shear forces on the sacrum and ischium were almost five times higher (15.5 N at last posture) than those on other sites (3.5 N on average) during experiments periods. In conclusion, the proposed shear sensor may be reliable and useful for measuring the shear force on human-machine interfaces. PMID:25445984

  15. Forces from highly focused laser beams: modeling, measurement and application to refractive index measurements

    CERN Document Server

    Knoener, G; Nieminen, T A; Heckenberg, N R; Rubinsztein-Dunlop, H

    2007-01-01

    The optical forces in optical tweezers can be robustly modeled over a broad range of parameters using generalsed Lorenz-Mie theory. We describe the procedure, and show how the combination of experimental measurement of properties of the trap coupled with computational modeling, can allow unknown parameters of the particle - in this case, the refractive index - to be determined.

  16. Ticks and Diseases: Bite Fright!

    Science.gov (United States)

    ... of this page please turn Javascript on. Feature: Ticks and Diseases Bite Fright! Past Issues / Spring - Summer ... can bring on serious health problems. What Are Ticks? If you spend any time outdoors, you've ...

  17. A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope.

    Science.gov (United States)

    Lange, Manfred; van Vörden, Dennis; Möller, Rolf

    2012-01-01

    Measurements of the frequency shift versus distance in noncontact atomic force microscopy (NC-AFM) allow measurements of the force gradient between the oscillating tip and a surface (force-spectroscopy measurements). When nonconservative forces act between the tip apex and the surface the oscillation amplitude is damped. The dissipation is caused by bistabilities in the potential energy surface of the tip-sample system, and the process can be understood as a hysteresis of forces between approach and retraction of the tip. In this paper, we present the direct measurement of the whole hysteresis loop in force-spectroscopy curves at 77 K on the PTCDA/Ag/Si(111) √3 × √3 surface by means of a tuning-fork-based NC-AFM with an oscillation amplitude smaller than the distance range of the hysteresis loop. The hysteresis effect is caused by the making and breaking of a bond between PTCDA molecules on the surface and a PTCDA molecule at the tip. The corresponding energy loss was determined to be 0.57 eV by evaluation of the force-distance curves upon approach and retraction. Furthermore, a second dissipation process was identified through the damping of the oscillation while the molecule on the tip is in contact with the surface. This dissipation process occurs mainly during the retraction of the tip. It reaches a maximum value of about 0.22 eV/cycle. PMID:22496993

  18. The management of snake bite*

    OpenAIRE

    Reid, H A; Theakston, R D G

    1983-01-01

    The present article reviews current knowledge on the epidemiology, pathophysiology, and treatment of snake bite, with particular reference to the situation in developing countries. There is little reliable information on the incidence of snake bite in many parts of the world, and epidemiological studies are needed, using enzyme-linked immunosorbent assay to identify and quantify serum levels of venom antigen and antibody. The pathophysiology and clinical features of envenoming by medically im...

  19. Measurement of the complete interaction force curve at the nanoscale

    OpenAIRE

    Rodrigues, Mario S.; Costa, Luca; Chevrier, Joel; Comin, Fabio

    2012-01-01

    The force between two interacting particles as a function of distance is one of the most fundamental curves in science. In this regard, Atomic Force Microscopy (AFM) represents the most powerful tool in nanoscience but with severe limits when it is to probe attractive interactions with high sensitivity. The Force Feedback Microscope (FFM) described here, removes from AFM the well known jump to contact problem that precludes the complete exploration of the interaction curve and the study of as...

  20. [Snake bite injuries].

    Science.gov (United States)

    Turchányi, B; Szalontay, T; Zacher, G

    2000-05-14

    Authors treated five patients who suffered venomous snake-bite injury. Although these snakes are not native in Hungary, this kind of injury is estimated to be more frequent, because of the increasing number of the private collections and illegal import of these reptiles. The local and general symptoms, the therapeutic steps are summarised in this study considering the literature as well. Two patients did not show any systemic or local symptoms at the level of injury, they needed only short observation, and woundcare. The other three patients had serious transient systematic symptoms (vasolability, hypotension/shock, coagulopathy, confusion). Two of them were given specific antivenom. As the third patient did not agree with the serum therapy, plasmapheresis was the choice to treat him, and it seemed to be effective. Few hours later the patients needed surgery because of serious compartment syndrome of their affected upper extremity. Surgical decompression of all the compartments and different possibilities of the secondary skin closure technique are demonstrated. Two patient healed completely, but the right thumb of the third was lost. Authors summarise the effects of the poisons, the symptoms, and the basic therapeutic steps during the first aid and in the primary hospital phase, respectively. They point out the indications of the serum therapy and the correct surgical decompression of the injured extremity. PMID:10851889

  1. A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope

    Directory of Open Access Journals (Sweden)

    Manfred Lange

    2012-03-01

    Full Text Available Measurements of the frequency shift versus distance in noncontact atomic force microscopy (NC-AFM allow measurements of the force gradient between the oscillating tip and a surface (force-spectroscopy measurements. When nonconservative forces act between the tip apex and the surface the oscillation amplitude is damped. The dissipation is caused by bistabilities in the potential energy surface of the tip–sample system, and the process can be understood as a hysteresis of forces between approach and retraction of the tip. In this paper, we present the direct measurement of the whole hysteresis loop in force-spectroscopy curves at 77 K on the PTCDA/Ag/Si(111 √3 × √3 surface by means of a tuning-fork-based NC-AFM with an oscillation amplitude smaller than the distance range of the hysteresis loop. The hysteresis effect is caused by the making and breaking of a bond between PTCDA molecules on the surface and a PTCDA molecule at the tip. The corresponding energy loss was determined to be 0.57 eV by evaluation of the force–distance curves upon approach and retraction. Furthermore, a second dissipation process was identified through the damping of the oscillation while the molecule on the tip is in contact with the surface. This dissipation process occurs mainly during the retraction of the tip. It reaches a maximum value of about 0.22 eV/cycle.

  2. Force measuring valve assemblies, systems including such valve assemblies and related methods

    Science.gov (United States)

    DeWall, Kevin George; Garcia, Humberto Enrique; McKellar, Michael George

    2012-04-17

    Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.

  3. A test program to measure fluid mechanical whirl-excitation forces in centrifugal pumps

    Science.gov (United States)

    Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1980-01-01

    The details of a test program for the measurement of the unsteady forces on centrifugal impellers are discussed. Various hydrodynamic flows are identified as possible contributors to these destabilizing forces.

  4. Lorentz force electrical impedance tomography using magnetic field measurements

    Science.gov (United States)

    Zengin, Reyhan; Güneri Gençer, Nevzat

    2016-08-01

    In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from -{{25}\\circ} to {{25}\\circ} at intervals of {{5}\\circ} . The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 dB. Simulation studies

  5. Lorentz force electrical impedance tomography using magnetic field measurements.

    Science.gov (United States)

    Zengin, Reyhan; Gençer, Nevzat Güneri

    2016-08-21

    In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from [Formula: see text] to [Formula: see text] at intervals of [Formula: see text]. The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 d

  6. Depletion interaction measured by colloidal probe atomic force microscopy

    NARCIS (Netherlands)

    Wijting, W.K.; Knoben, W.; Besseling, N.A.M.; Leermakers, F.A.M.; Cohen Stuart, M.A.

    2004-01-01

    We investigated the depletion interaction between stearylated silica surfaces in cyclohexane in the presence of dissolved polydimethylsiloxane by means of colloidal probe atomic force microscopy. We found that the range of the depletion interaction decreases with increasing concentration. Furthermor

  7. Assessment of open and incomplete bite correction by incisor overlap and optical density of polyvinyl siloxane bite registration.

    Science.gov (United States)

    Shpack, Nir; Einy, Shmuel; Beni, Lea; Vardimon, Alexander D

    2006-04-01

    Open bite (OB) is a generalized term, which could incorporate subgroups that react differently to vertical correction. The objectives of the present study were to detect vertical treatment changes in incomplete bite (IB: inter-incisor overlap with no lower incisor contact with teeth or palate) and OB (no inter-incisor overlap) groups compared with a complete bite (CB: inter-incisor overlap with full lower incisor contact with teeth or palate) control group, to evaluate treatment response of the central and lateral incisors, and to study the vertico-sagittal interaction. Dental casts were taken at three time points, pre-treatment, post-treatment, and after one year of retention, from 54 Class II patients (22 males and 32 females with a mean age of 11 years 6 months) divided into three groups: CB (n = 21), IB (n = 18) and OB (n = 15). Measurements included incisor overlap (mm) and optical density (OD/mm2) of occlusal bite registration made of polyvinl siloxane. Both CB and IB groups demonstrated post-retention bite opening. However, bite opening in the CB group was three times greater than that in the IB group (e.g. lower lateral = -1.42 mm, 118 OD/mm2 versus -0.40 mm, 107 OD/mm2). Conversely, the OB group showed a significant (P < 0.001) bite closure (e.g. lower lateral = 1.30 mm, -377 OD/mm2). Overjet changes affected OD measurements, causing diversity in OD and millimetric measurements of the lateral incisors in the IB group. In conclusion, the OB group demonstrated a significant stable vertical correction; a post-treatment non-contact inter-incisor relationship was determined by a vertico-sagittal relapse; and full compensation of an IB was not possible.

  8. Flow velocimetry for weakly conducting electrolytes based on high resolution Lorentz force measurement.

    Science.gov (United States)

    Resagk, Christian; Ebert, Reschad; Vasilyan, Suren; Wiederhold, Andreas

    2013-11-01

    We demonstrate that a flow velocity measurement can be transformed into a non-invasive force measurement by metering the drag force acting on a system of magnets around a flow channel. This method is called Lorentz force velocimetry and has been developed in the last years in our institute. It is a feasible principle for materials with large conductivity like liquid metals. To evolve this method for weakly conducting fluids like salt water or molten glass the drag force measurement is the challenging bottleneck. Here forces of 10-8 and less of the weight force of the magnet system have to be resolved. In this paper different force measurement techniques get tested and compared. For the current setup the magnet system is attached to a state of the art electromagnetic force compensation balance. Different ways of getting the correct force signal out of the two measurement setups will be presented and discussed. For generalization of the measurement principle the Lorentz force is determined for different fluid profiles. In addition to that we have developed new systematic noise reduction methods to increase the resolution of the force measurement techniques by a factor of ten or larger which we will present here.

  9. High-precision horizontally directed force measurements for high dead loads based on a differential electromagnetic force compensation system

    Science.gov (United States)

    Vasilyan, Suren; Rivero, Michel; Schleichert, Jan; Halbedel, Bernd; Fröhlich, Thomas

    2016-04-01

    In this paper, we present an application for realizing high-precision horizontally directed force measurements in the order of several tens of nN in combination with high dead loads of about 10 N. The set-up is developed on the basis of two identical state-of-the-art electromagnetic force compensation (EMFC) high precision balances. The measurement resolution of horizontally directed single-axis quasi-dynamic forces is 20 nN over the working range of  ±100 μN. The set-up operates in two different measurement modes: in the open-loop mode the mechanical deflection of the proportional lever is an indication of the acting force, whereas in the closed-loop mode it is the applied electric current to the coil inside the EMFC balance that compensates deflection of the lever to the offset zero position. The estimated loading frequency (cutoff frequency) of the set-up in the open-loop mode is about 0.18 Hz, in the closed-loop mode it is 0.7 Hz. One of the practical applications that the set-up is suitable for is the flow rate measurements of low electrically conducting electrolytes by applying the contactless technique of Lorentz force velocimetry. Based on a previously developed set-up which uses a single EMFC balance, experimental, theoretical and numerical analyses of the thermo-mechanical properties of the supporting structure are presented.

  10. Forced excitation and active control for the measurement of fluid-elastic forces

    International Nuclear Information System (INIS)

    The action of a fluid flow on a tubes bundle is commonly decomposed into a random turbulent excitation and a fluid-elastic excitation. The fluid-elastic forces which are coupled to the tubes movement can be experimentally determined from an analysis of the vibratory response of the structure excited by turbulent forces. For low flow velocities, the turbulent excitation can be insufficient to make the tube significantly vibrate and to permit a correct vibratory analysis. On the opposite side, the structure can become unstable for high flow velocities: the fluid-elastic forces make the fluid-structure damping system fall towards zero. Two experimental methods are proposed in order to extend the considered flow rate. An additional excitation force allows to increase the tube vibration level for improving the signal-noise ratio at low velocities. When the tube is submitted to fluid-elastic instability, an artificial damping contribution by active control allows to stabilize it. Methods are implemented on a flexible tube inserted into rigid tubes bundle water and water-air transverse flows. Two actuator technologies are used: an electromagnetic exciter and piezoelectric actuators. The additional excitation method shows that the fluid-elastic forces remain insignificant at low velocity single phase flow. With the active control method, it is possible to carry out tests beyond the fluid-elastic instability. In two-phase flow, the stabilization of the structure is observed for low vacuum rates. The obtained new results are analyzed with the literature expected results in terms of fluid-elastic coupling and turbulent excitation. (author)

  11. Transducer for Tension Force Measuring of Strip Materials

    Directory of Open Access Journals (Sweden)

    Emad S. Addasi

    2005-01-01

    Full Text Available In winding-up motor drive systems, such as that used in textile industry, it is very important to get a constant tension force for the winding strip material (thread and to reduce its oscillations. This study recommends a transducer with a special design to be used in the mentioned motor drive systems. By using a piston damper, spring, levers, slider and other simple components the suggested sensor (transducer can be used to control the motor speed for getting the required thread tension force. Also the suggested transducer avoids the disadvantage of other used conventional transducer: the parasitic (detrimental oscillations of the thread tension force, which affect the quality of the produced strip material.

  12. How to Keep Bug Bites At Bay

    Science.gov (United States)

    ... gov/news/fullstory_160047.html How to Keep Bug Bites at Bay CDC offers advice on thwarting ... 23, 2016 SATURDAY, July 23, 2016 (HealthDay News) -- Bug bites can make you more than itchy. Ticks, ...

  13. Precise force measurement method by a Y-shaped cavity dual-frequency laser

    Institute of Scientific and Technical Information of China (English)

    Guangzong Xiao; Xingwu Long; Bin Zhang; Geng Li

    2011-01-01

    A novel precise force measurement based on a Y-shaped cavity dual-frequency laser is proposed. The principle of force measurement with this method is analyzed, and the analytic relation expression between the input force and the change in the output beat frequency is derived. Experiments using a 632.8-nm Y-shaped cavity He-Ne dual-frequency laser are then performed; they demonstrate that the force measurement is proportional to a high degree over almost five decades of input signal range. The maximum scale factor is observed as 5.02×109 Hz/N, with beat frequency instability equivalent resolution of 10-5 N. By optimizing the optical and geometrical parameters of the laser sensor, a force measurement resolution of 10-6i N could be expected.%A novel precise force measurement based on a Y-shaped cavity dual-frequency laser is proposed.The principle of force measurement with this method is analyzed,and the analytic relation expression between the input force and the change in the output beat frequency is derived.Experiments using a 632.8-nm Y-shaped cavity He-Ne dual-frequency laser are then performed;they demonstrate that the force measurement is proportional to a high degree over almost five decades of input signal range.The maximum scale factor is observed as 5.02× 109 Hz/N,with beat frequency instability equivalent resolution of 10-5 N.By optimizing the optical and geometrical parameters of the laser sensor,a force measurement resolution of 10 -6 N could be expected.Precise measurement of force and force-related nagnitudes,such as acceleration,pressure,and mass,is an often demanded task in modern engineering and science[1-3].In recent decades,some research efforts have been intensified to utilize optical measnrement procedures for obtaining precise force measurement.

  14. Improvement of strain gauges micro-forces measurement using Kalman optimal filtering.

    OpenAIRE

    Haddab, Yassine; Chen, Qiao; Lutz, Philippe

    2009-01-01

    International audience Manipulation of small components and assembly of Microsystems require force measurement. In the microworld (the world of very small components), signal/noise ratio is very low due to the weak amplitude of the signals. To be used in feedback control or in a micromanipulation system, a force sensor must allow static and dynamic measurements. In this paper, we present a micro-force measurement system based on the use of strain gauges and a Kalman optimal filter. Using a...

  15. Data on force-dependent structural changes of chromatin fibers measured with magnetic tweezers

    Directory of Open Access Journals (Sweden)

    Fan-Tso Chien

    2014-12-01

    Full Text Available The compaction of chromatin fibers regulates the accessibility of embedded DNA, highly associated with transcriptional activities [1]. Single molecule force spectroscopy has revealed the great details of the structural changes of chromatin fibers in the presence of external exerted force [2–7]. However, most of the studies focus on a specific force regime [2,3,8,9]. The data here show force-extension (FE traces of chromatin fibers as measured with magnetic tweezers, covering the force regime from 0 pN to 27 pN. Those traces provide information for further studies at varied force regimes.

  16. Heridas por Mordedura / Bites Injuries

    Directory of Open Access Journals (Sweden)

    Coturel A

    2015-11-01

    Full Text Available Injuries for animal bites are a common cause of consultation to emergency services. However there are still controversies about some aspects of their treatment. It is not recommended to brush the wound area but to flush the surface with isoosmolar saline. The primary wound closure is justified when improves the cosmetic outcome and has no increase risk of infection. Antibiotic prophylaxis is allways indicated in cats or humans bites. The drug of choice is amoxicillin clavulanate.The tetanus vaccine should be indicated when the patient has not full vaccination scheme and rabies vaccine in cases of suspected or confirmed infected animals.

  17. The big shift: measuring the forces of change

    DEFF Research Database (Denmark)

    Hagel, John; Brown, John Seely; Davison, Lang

    2009-01-01

    Traditional metrics don't capture many of the challenges and opportunities in store for U.S. companies and the national economy. The authors, from Deloitte, present a framework for understanding the forces that have transformed business over the past 40 years--and an index for gauging their impac...

  18. Weibull analyses of bacterial interaction forces measured using AFM

    NARCIS (Netherlands)

    van der Mei, Henderina; de Vries, Jacob; Busscher, Hendrik

    2010-01-01

    Statistically significant conclusions from interaction forces obtained by AFM are difficult to draw because of large data spreads. Weibull analysis, common in macroscopic bond-strength analyses, takes advantage of this spread to derive a Weibull distribution, yielding the probability of occurrence o

  19. The big shift: measuring the forces of change

    DEFF Research Database (Denmark)

    Hagel, John; Brown, John Seely; Davison, Lang

    2009-01-01

    Traditional metrics don't capture many of the challenges and opportunities in store for U.S. companies and the national economy. The authors, from Deloitte, present a framework for understanding the forces that have transformed business over the past 40 years--and an index for gauging their impact...

  20. Force measurement platform for training and assessment of laparoscopic skills

    NARCIS (Netherlands)

    Horeman, T.; Rodrigues, S.P.; Jansen, F.W.; Dankelman, J.; Van den Dobbelsteen, J.J.

    2010-01-01

    Background - To improve endoscopic surgical skills, an increasing number of surgical residents practice on box or virtual-reality (VR) trainers. Current training is mainly focused on hand–eye coordination. Training methods that focus on applying the right amount of force are not yet available. Metho

  1. Statistical Analysis of Long- and Short-Range Forces Involved in Bacterial Adhesion to Substratum Surfaces as Measured Using Atomic Force Microscopy ▿

    OpenAIRE

    CHEN, YUN; Henk J Busscher; van der Mei, Henny C.; Norde, Willem

    2011-01-01

    Surface thermodynamic analyses of microbial adhesion using measured contact angles on solid substrata and microbial cell surfaces are widely employed to determine the nature of the adhesion forces, i.e., the interplay between Lifshitz-van der Waals and acid-base forces. While surface thermodynamic analyses are often viewed critically, atomic force microscopy (AFM) can also provide information on the nature of the adhesion forces by means of Poisson analysis of the measured forces. This review...

  2. Rope test may indicate efficacy of tail-biting treatments in growing pigs

    NARCIS (Netherlands)

    Bracke, M.B.M.

    2009-01-01

    Tail biting is a most serious welfare problem in pigs raised for slaughter. In instances of an outbreak of tail biting, scientists have recommended that farmers take measures such as removal of affected animals, provision of enrichment materials and application of repellents to the pigs' tails. Howe

  3. Biophysical characterization of DNA binding from single molecule force measurements

    OpenAIRE

    Chaurasiya, Kathy R.; Paramanathan, Thayaparan; McCauley, Micah J.; Williams, Mark C.

    2010-01-01

    Single molecule force spectroscopy is a powerful method that uses the mechanical properties of DNA to explore DNA interactions. Here we describe how DNA stretching experiments quantitatively characterize the DNA binding of small molecules and proteins. Small molecules exhibit diverse DNA binding modes, including binding into the major and minor grooves and intercalation between base pairs of double-stranded DNA (dsDNA). Histones bind and package dsDNA, while other nuclear proteins such as hig...

  4. Food aroma affects bite size

    NARCIS (Netherlands)

    Wijk, de R.A.; Polet, I.A.; Boek, W.; Coenraad, S.; Bult, J.H.F.

    2012-01-01

    Background
    To evaluate the effect of food aroma on bite size, a semisolid vanilla custard dessert was delivered repeatedly into the mouth of test subjects using a pump while various concentrations of cream aroma were presented retronasally to the nose. Termination of the pump, which determined b

  5. The management of snake bite.

    Science.gov (United States)

    Reid, H A; Theakston, R D

    1983-01-01

    The present article reviews current knowledge on the epidemiology, pathophysiology, and treatment of snake bite, with particular reference to the situation in developing countries. There is little reliable information on the incidence of snake bite in many parts of the world, and epidemiological studies are needed, using enzyme-linked immunosorbent assay to identify and quantify serum levels of venom antigen and antibody. The pathophysiology and clinical features of envenoming by medically important snakes are discussed. Antivenom, if used correctly, can reverse systemic poisoning even if given days after the bite. It is therefore wise to wait for the appearance of signs of systemic poisoning before administering antivenom, rather than using it routinely. WHO has designated the Liverpool School of Tropical Medicine as a Collaborating Centre for the Control of Antivenoms, and this Centre now holds a collection of reference venoms from several important snake species. Characterization of these and of standard antivenoms should significantly improve the management of snake bite throughout the world. PMID:6609008

  6. Vertical Magnetic Levitation Force Measurement on Single Crystal YBaCuO Bulk at Different Temperatures

    Science.gov (United States)

    Celik, Sukru; Guner, Sait Baris; Ozturk, Kemal; Ozturk, Ozgur

    Magnetic levitation force measurements of HTS samples are performed with the use of liquid nitrogen. It is both convenient and cheap. However, the temperature of the sample cannot be changed (77 K) and there is problem of frost. So, it is necessary to build another type of system to measure the levitation force high Tc superconductor at different temperatures. In this study, we fabricated YBaCuO superconducting by top-seeding-melting-growth (TSMG) technique and measured vertical forces of them at FC (Field Cooling) and ZFC (Zero Field Cooling) regimes by using our new designed magnetic levitation force measurement system. It was used to investigate the three-dimensional levitation force and lateral force in the levitation system consisting of a cylindrical magnet and a permanent cylindrical superconductor at different temperatures (37, 47, 57, 67 and 77 K).

  7. What is credible and what is incredible in the measurements of the Casimir force

    CERN Document Server

    Klimchitskaya, G L

    2010-01-01

    We comment on progress in measurements of the Casimir force and discuss what is the actual reliability of different experiments. In this connection a more rigorous approach to the usage of such concepts as accuracy, precision, and measure of agreement between experiment and theory, is presented. We demonstrate that all measurements of the Casimir force employing spherical lenses with centimeter-size curvature radii are fundamentally flawed due to the presence of bubbles and pits on their surfaces. The commonly used formulation of the proximity force approximation is shown to be inapplicable for centimeter-size lenses. New expressions for the Casimir force are derived taking into account surface imperfections. Uncontrollable deviations of the Casimir force from the values predicted using the assumption of perfect sphericity vary by a few tens of percent within the separation region from 1 to $3\\,\\mu$m. This makes impractical further use of centimeter-size lenses in experiments on measuring the Casimir force.

  8. Measurement of the gold–gold bond rupture force at 4 K in a single-atom chain using photon-momentum-based force calibration

    International Nuclear Information System (INIS)

    We present instrumentation and methodology for simultaneously measuring force and displacement at the atomic scale at 4 K. The technique, which uses a macroscopic cantilever as a force sensor and high-resolution, high-stability fiber-optic interferometers for displacement measurement, is particularly well-suited to making accurate, traceable measurements of force and displacement in nanometer- and atomic-scale mechanical deformation experiments. The technique emphasizes accurate co-location of force and displacement measurement and measures cantilever stiffness at the contact point in situ at 4 K using photon momentum. We present preliminary results of measurements made of the force required to rupture a single atomic bond in a gold single-atom chain formed between a gold flat and a gold tip. Finally, we discuss the possible use of the gold–gold bond rupture force as an intrinsic force calibration value for forces near 1 nN. (paper)

  9. Estimation of Cable Forces of a Guyed Mast from Dynamic Measurements

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Hansen, Lars Pilegaard

    This paper presents how the tension forces in the cables of a 200 m. high guyed mast have been estimated from natural frequencies obtained from acceleration measurements.The mast is guyed at five levels with three guys at 120 degree intervals at each level. The accelerations in three directions...... were measured in five cables. The relationship between frequencies and cable forces have been establish assuming the cables to behave in linear manner. The results show that estimated cables forces correspond very well to the expected. The results obtained showed that it was possible to obtain reliable...... estimates for cables forces based on measured natural frequencies....

  10. Towards a precision measurement of the Casimir force in a cylinder-plane geometry

    OpenAIRE

    Brown-Hayes, Michael; Dalvit, Diego A. R.; Mazzitelli, Francisco D.; Kim, Woo-Joong; Onofrio, Roberto

    2005-01-01

    We report on a proposal aimed at measuring the Casimir force in a cylinder-plane configuration. The Casimir force is evaluated including corrections due to finite parallelism, conductivity, and temperature. The range of validity of the proximity force approximation is also discussed. An apparatus to test the feasibility of a precision measurement in this configuration has been developed, and we describe both a procedure to control the parallelism and the results of the electrostatic calibrati...

  11. Colored polydimethylsiloxane micropillar arrays for high throughput measurements of forces applied by genetic model organisms

    OpenAIRE

    Khare, Siddharth M.; Awasthi, Anjali; V. Venkataraman; Sandhya P Koushika

    2015-01-01

    Measuring forces applied by multi-cellular organisms is valuable in investigating biomechanics of their locomotion. Several technologies have been developed to measure such forces, for example, strain gauges, micro-machined sensors, and calibrated cantilevers. We introduce an innovative combination of techniques as a high throughput screening tool to assess forces applied by multiple genetic model organisms. First, we fabricated colored Polydimethylsiloxane (PDMS) micropillars where the color...

  12. Temperature and force dependence of electron transport via the copper protein azurin: conductive probe atomic force microscopy measurements

    CERN Document Server

    Li, Wenjie; Amdursky, Nadav; Cohen, Sidney R; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2012-01-01

    We report conducting probe atomic force microscopy (CP-AFM) measurements of electron transport (ETp), as a function of temperature and force, through monolayers of holo-azurin (holo-Az) and Cu-depleted Az (apo-Az) that retain only their tightly bound water, immobilized on gold surfaces. The changes in CP-AFM current-voltage (I-V) curves for holo-Az and apo-Az, measured between 250 - 370K, are strikingly different. While ETp across holo-Az at low force (6 nN) is temperature-independent over the whole examined range, ETp across apo-Az is thermally activated, with calculated activation energy of 600\\pm100 meV. These results confirm our results of macroscopic contact area ETp measurements via holo- and apo-Az, as a function of temperature, where the crucial role of the Cu redox centre has been observed. While increasing the applied tip force from 6 to 12 nN did not significantly change the temperature dependence of ETp via apo-Az, ETp via holo-Az changed qualitatively, namely from temperature-independent at 6 nN ...

  13. Measuring anisotropic friction on WTe2 using atomic force microscopy in the force-distance and friction modes.

    Science.gov (United States)

    Watson, Gregory S; Myhra, Sverre; Watson, Jolanta A

    2010-04-01

    Layered materials which can be easily cleaved have proved to be excellent samples for the study of atomic scale friction. The layered transition metal dichalcogenides have been particularly popular. These materials exhibit a number of interesting properties ranging from superconductivity to low frictional coefficients. In this paper we have investigated the tribology of the dichalcogenide-WTe2. The coefficient of friction is less than 0.040 along the Te rows and increases to over 0.045 across the rows. The frictional forces almost doubled at normal loads of 5000 nN when scanning in the [010] direction in comparison to the [100] direction. The frictional responses of the AFM probe have been monitored in the frictional force and force-versus-distance (f-d) mode. A comparison between the outcomes using the two different modes demonstrates the factors which need to be considered for accurate measurements. PMID:20355449

  14. A protocol for variable-resolution first-order reversal curve (FORC) measurements

    Science.gov (United States)

    Heslop, David; Zhao, Xiang; Roberts, Andrew

    2016-04-01

    High-resolution first-order reversal curve (FORC) diagrams are being increasingly used in rock and environmental magnetism, including for detection of biomagnetic signals in sediments. Resolution can be a major barrier to obtaining high-quality FORC diagrams and timeconsuming measurements that employ small field steps are necessary to resolve the finest features of a FORC distribution. We present a new experimental protocol with irregularly spaced field steps that allow different parts of a FORC diagram to be measured at different resolutions. Larger numbers of measurements can, therefore, be made in key regions of a FORC distribution to resolve diagnostic features at higher resolution. Specification of the field steps in the irregular measurement grid is based on major hysteresis properties; no a priori knowledge concerning the underlying FORC distribution is required. FORC diagrams obtained with conventional measurements and with our new measurement protocol give consistent results. Because of its variable resolution, the irregular protocol provides a clear representation of finescale features produced by quasi-reversible superparamagnetic and non-interacting singledomain particles. Although the proposed irregular measurement protocol is not as efficient at suppressing noise as recently developed post-processing techniques (e.g., VARIFORC, Egli [2013]), it enables efficient high-resolution analysis for relatively strongly magnetized samples where measurement noise is not detrimental to FORC distribution estimation.

  15. A Measurement of the Force between Two Current-Carrying Wires

    Science.gov (United States)

    Straulino, S.; Cartacci, A.

    2014-01-01

    The measurement of the force acting between two parallel, current-carrying wires is known as Ampère's experiment. A mechanical balance was historically employed to measure that force. We report a simple experiment based on an electronic precision balance that is useful in clearly showing students the existence of this interaction and how to…

  16. Complex Squeezing and Force Measurement Beyond the Standard Quantum Limit

    CERN Document Server

    Buchmann, L F; Kohler, J; Spethmann, N; Stamper-Kurn, D M

    2016-01-01

    A continuous quantum field, such as a propagating beam of light, may be characterized by a squeezing spectrum that is inhomogeneous in frequency. We point out that homodyne detectors, which are commonly employed to detect quantum squeezing, are blind to squeezing spectra in which the correlation between amplitude and phase fluctuations is complex. We find theoretically that such complex squeezing is a component of ponderomotive squeezing of light through cavity optomechanics. We propose a detection scheme, called synodyne detection, which reveals complex squeezing and allows its use to improve force detection beyond the standard quantum limit.

  17. Measurement of cell adhesion force by vertical forcible detachment using an arrowhead nanoneedle and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Seunghwan; Hashizume, Yui; Mishima, Mari [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Kawamura, Ryuzo [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562 (Japan); Tamura, Masato; Matsui, Hirofumi [Faculty of Medicine, University of Tsukuba, 1-1-1 Ten-nohdai, Tsukuba, Ibaraki 305-8573 (Japan); Matsusaki, Michiya; Akashi, Mitsuru [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nakamura, Chikashi, E-mail: chikashi-nakamura@aist.go.jp [Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562 (Japan)

    2014-08-15

    Graphical abstract: - Highlights: • We developed a method to measure cell adhesion force by detaching cell using an arrowhead nanoneedle and AFM. • A nanofilm consisting of fibronectin and gelatin was formed on cell surface to reinforce the cell cortex. • By the nanofilm lamination, detachment efficiencies of strongly adherent cell lines were improved markedly. - Abstract: The properties of substrates and extracellular matrices (ECM) are important factors governing the functions and fates of mammalian adherent cells. For example, substrate stiffness often affects cell differentiation. At focal adhesions, clustered–integrin bindings link cells mechanically to the ECM. In order to quantitate the affinity between cell and substrate, the cell adhesion force must be measured for single cells. In this study, forcible detachment of a single cell in the vertical direction using AFM was carried out, allowing breakage of the integrin–substrate bindings. An AFM tip was fabricated into an arrowhead shape to detach the cell from the substrate. Peak force observed in the recorded force curve during probe retraction was defined as the adhesion force, and was analyzed for various types of cells. Some of the cell types adhered so strongly that they could not be picked up because of plasma membrane breakage by the arrowhead probe. To address this problem, a technique to reinforce the cellular membrane with layer-by-layer nanofilms composed of fibronectin and gelatin helped to improve insertion efficiency and to prevent cell membrane rupture during the detachment process, allowing successful detachment of the cells. This method for detaching cells, involving cellular membrane reinforcement, may be beneficial for evaluating true cell adhesion forces in various cell types.

  18. Records of assassin bug species (reduviidae, heteroptera reported biting man

    Directory of Open Access Journals (Sweden)

    E.K. Hartwig

    1977-08-01

    Full Text Available In southern Africa Acanthaspis obscura Stal, Pirates conspurcatus Distant, Rhinocoris segmentarius (Germar and Panto-feistes pnnceps Stal intlict painful bites on humans. Serious consequences can develop. This is unknown to the public in general. Adult A. obscura and P. conspurcatus are responsible for the greatest number of bites because they are positively phototropic. R, segmentarius is not attracted to light but is the most common local species. Bites happen accidentally and could largely be avoided if the bugs could be recognized. The first three species have a wide distribution. Various insects are preyed on. The R. segmentarius female can lay 358 fertile eggs in six batches over a period of 77 days without copulating once in this period. Adults are most active in mid-summer although found throughout the year. These three species are abundant in some years and scarce in others. Preventive measures include screening homes and decoy lights. Control involves spraying with carbaryl.

  19. Force Measurement Services at Kebs: AN Overview of Equipment, Procedures and Uncertainty

    Science.gov (United States)

    Bangi, J. O.; Maranga, S. M.; Nganga, S. P.; Mutuli, S. M.

    This paper describes the facilities, instrumentation and procedures currently used in the force laboratory at the Kenya Bureau of Standards (KEBS) for force measurement services. The laboratory uses the Force Calibration Machine (FCM) to calibrate force-measuring instruments. The FCM derives its traceability via comparisons using reference transfer force transducers calibrated by the Force Standard Machines (FSM) of a National Metrology Institute (NMI). The force laboratory is accredited to ISO/IEC 17025 by the Germany Accreditation Body (DAkkS). The accredited measurement scope of the laboratory is 1 MN to calibrate force transducers in both compression and tension modes. ISO 376 procedures are used while calibrating force transducers. The KEBS reference transfer standards have capacities of 10, 50, 300 and 1000 kN to cover the full range of the FCM. The uncertainty in the forces measured by the FCM were reviewed and determined in accordance to the new EURAMET calibration guide. The relative expanded uncertainty of force W realized by FCM was evaluated in a range from 10 kN-1 MN, and was found to be 5.0 × 10-4 with the coverage factor k being equal to 2. The overall normalized error (En) of the comparison results was also found to be less than 1. The accredited Calibration and Measurement Capability (CMC) of the KEBS force laboratory was based on the results of those intercomparisons. The FCM enables KEBS to provide traceability for the calibration of class ‘1’ force instruments as per the ISO 376.

  20. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams

    Science.gov (United States)

    Spethmann, A.; Trottenberg, T.; Kersten, H.

    2015-01-01

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements.

  1. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Spethmann, A., E-mail: spethmann@physik.uni-kiel.de; Trottenberg, T., E-mail: trottenberg@physik.uni-kiel.de; Kersten, H., E-mail: kersten@physik.uni-kiel.de [Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel (Germany)

    2015-01-15

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements.

  2. Measurement of swimming force generation during flagella regeneration in Chlamydomonas reinhardtii

    Science.gov (United States)

    Yukich, John N.; Shaban, Mona; Clodfelter, Catherine; Bernd, Karen

    2007-11-01

    The green alga Chlamydomonas reinhardtii has been at the forefront of many studies investigating the establishment and function of flagella in facilitating cellular motility. Previously we reported an intriguing pattern during flagella regeneration in which increases in force do not always correspond with increase in flagella length. That work made direct measurement of maximum flagellar swimming force by measuring the cell's ability to escape from an optical trap (optical tweezers). Here, we report on optimization and automation of the force measurement using power spectral density calibration of the trap and distance of periodic displacement from the trap center. This process yields an average value for the swimming force. The intriguing pattern described for maximum swimming force is also evident in the average swimming force data, suggesting that the phenomenon reflects a change in flagella functionality during regeneration.

  3. Adhesion forces in interactive mixtures for dry powder inhalers--evaluation of a new measuring method.

    Science.gov (United States)

    Lohrmann, Maike; Kappl, Michael; Butt, Hans-Juergen; Urbanetz, Nora Anne; Lippold, Bernhard Christian

    2007-09-01

    Dry powder inhalers mostly contain carrier based formulations where micronized drug particles are adhered to coarse carrier particles. The performance of the dry powder inhaler depends on the inhaler device, the inhalation manoeuvre and the formulation. The most important factor influencing the behaviour of the formulation is the adhesion force acting between the active ingredient and the carrier particles, which can be measured using different methods, for example the centrifuge technique or atomic force microscopy. In this study the tensile strength method, usually applied to determine cohesion forces between powder particles of one material, is optimized for adhesion force measurements between powder particles of unlike materials. Adhesion force measurements between the carrier materials lactose or mannitol and the drug substance salbutamol sulphate using the tensile strength method and the atomic force microscopy show higher values with increasing relative humidity. Consequently, the fine particle fraction determined using the Next Generation Impactor decreases with increasing relative humidity as a result of the enhanced interparticle interactions.

  4. A wearable force plate system for the continuous measurement of triaxial ground reaction force in biomechanical applications

    Science.gov (United States)

    Liu, Tao; Inoue, Yoshio; Shibata, Kyoko

    2010-08-01

    The ambulatory measurement of ground reaction force (GRF) and human motion under free-living conditions is convenient, inexpensive and never restricted to gait analysis in a laboratory environment and is therefore much desired by researchers and clinical doctors in biomedical applications. A wearable force plate system was developed by integrating small triaxial force sensors and three-dimensional (3D) inertial sensors for estimating dynamic triaxial GRF in biomechanical applications. The system, in comparison to existent systems, is characterized by being lightweight, thin and easy-to-wear. A six-axial force sensor (Nitta Co., Japan) was used as a verification measurement device to validate the static accuracy of the developed force plate. To evaluate the precision during dynamic gait measurements, we compared the measurements of the triaxial GRF and the center of pressure (CoP) by using the developed system with the reference measurements made using a stationary force plate and an optical motion analysis system. The root mean square (RMS) differences of the two transverse components (x- and y-axes) and the vertical component (z-axis) of the GRF were 4.3 ± 0.9 N, 6.0 ± 1.3 N and 12.1 ± 1.1 N, respectively, corresponding to 5.1 ± 1.1% and 6.5 ± 1% of the maximum of each transverse component and 1.3 ± 0.2% of the maximum vertical component of GRF. The RMS distance between the two systems' CoP traces was 3.2 ± 0.8 mm, corresponding to 1.2 ± 0.3% of the length of the shoe. Moreover, based on the results of the assessment of the influence of the system on natural gait, we found that gait was almost never affected. Therefore, the wearable system as an alternative device can be a potential solution for measuring CoP and triaxial GRF in non-laboratory environments.

  5. Reduction of Liquid Bridge Force for 3D Microstructure Measurements

    OpenAIRE

    Hiroshi Murakami; Akio Katsuki; Takao Sajima; Mitsuyoshi Fukuda

    2016-01-01

    Recent years have witnessed an increased demand for a method for precise measurement of the microstructures of mechanical microparts, microelectromechanical systems, micromolds, optical devices, microholes, etc. This paper presents a measurement system for three-dimensional (3D) microstructures that use an optical fiber probe. This probe consists of a stylus shaft with a diameter of 2.5 µm and a glass ball with a diameter of 5 µm attached to the stylus tip. In this study, the measurement syst...

  6. Evaluation of a Blade Force Measurement System for a Vertical Axis Wind Turbine Using Load Cells

    Directory of Open Access Journals (Sweden)

    Morgan Rossander

    2015-06-01

    Full Text Available Unique blade force measurements on an open site straight-bladed vertical axis wind turbine have been performed. This paper presents a method for measuring the tangential and normal forces on a 12-kW vertical axis wind turbine prototype with a three-bladed H-rotor. Four single-axis load cells were installed in-between the hub and the support arms on one of the blades. The experimental setup, the measurement principle, together with the necessary control and measurement system are described. The maximum errors of the forces and accompanying weather data that can be obtained with the system are carefully estimated. Measured forces from the four load cells are presented, as well as the normal and tangential forces derived from them and a comparison with theoretical data. The measured torque and bending moment are also provided. The influence of the load cells on the turbine dynamics has also been evaluated. For the aerodynamic normal force, the system provides periodic data in agreement with simulations. Unexpected mechanical oscillations are present in the tangential force, introduced by the turbine dynamics. The measurement errors are of an acceptable size and often depend on the measured variable. Equations are presented for the calculation of measurement errors.

  7. On the correct interpretation of measured force and calculation of material stress in biaxial tests.

    Science.gov (United States)

    Nolan, D R; McGarry, J P

    2016-01-01

    Biaxial tests are commonly used to investigate the mechanical behaviour of soft biological tissues and polymers. In the current paper we uncover a fundamental problem associated with the calculation of material stress from measured force in standard biaxial tests. In addition to measured forces, localised unmeasured shear forces also occur at the clamps and the inability to quantify such forces has significant implications for the calculation of material stress from simplified force-equilibrium relationships. Unmeasured shear forces are shown to arise due to two distinct competing contributions: (1) negative shear force due to stretching of the orthogonal clamp, and (2) positive shear force as a result of material Poisson-effect. The clamp shear force is highly dependent on the specimen geometry and the clamp displacement ratio, as consequently, is the measured force-stress relationship. Additionally in this study we demonstrate that commonly accepted formulae for the estimation of material stress in the central region of a cruciform specimen are highly inaccurate. A reliable empirical correction factor for the general case of isotropic materials must be a function of specimen geometry and the biaxial clamp displacement ratio. Finally we demonstrate that a correction factor for the general case of non-linear anisotropic materials is not feasible and we suggest the use of inverse finite element analysis as a practical means of interpreting experimental data for such complex materials. PMID:26327453

  8. A new 3D levitation force measuring device for REBCO bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.L. [School of Physics, Shaanxi Normal University, Xi’an 710062 (China); Yang, W.M., E-mail: yangwm@snnu.edu.cn [School of Physics, Shaanxi Normal University, Xi’an 710062 (China); Li, J.W.; Yuan, X.C. [School of Physics, Shaanxi Normal University, Xi’an 710062 (China); Ma, J. [School of Physics, Shaanxi Normal University, Xi’an 710062 (China); Department of Physics, Qinghai Normal University, Xining 810008 (China); Wang, M. [School of Physics, Shaanxi Normal University, Xi’an 710062 (China)

    2014-01-15

    Highlights: •A new 3D levitation force measuring device has been designed and constructed. •It can measure the 3D real-time interaction force simultaneously and directly. •Performance, accuracy and effectiveness has been demonstrate by tests. -- Abstract: A new 3D levitation force measuring device for ReBa{sub 2}Cu{sub 3}O{sub 7−x} (REBCO) bulk superconductors has been designed and constructed. Three pull pressure load cells are orthogonally set on a fixing bracket to test the interaction force between a bulk superconductor and a magnet in three dimensions. To realize the simple, rapid and accurate measurement of the levitation force, a non-magnetic hollow cylinder flange, three pull pressure load cells, a piece of iron plate, a NbFeB permanent magnet (PM) and some steel balls are elaborately constructed with the fixing bracket, thus the magnet or REBCO bulk superconductor can be well and rigidly connected with the load cells, and the mutual interference from the three pull pressure load cells can be effectively avoided during the levitation force measuring processes. This device can be used to measure the interaction (or levitation) force between a superconductor and a magnet, that between a magnet and a magnet, or the magnetic force among magnetic materials in three dimensions.

  9. Optomechanical Measurement of the Abraham Force in an Adiabatic Liquid Core Optical Fiber Waveguide

    CERN Document Server

    Choi, H; Elliott, D S; Oh, K

    2016-01-01

    We report quantitative experimental measurements of the Abraham force associated with a propagating optical wave. We isolate this force using a guided light wave undergoing an adiabatic mode transformation (AMT) along a liquid-filled hollow optical fiber (HOF). Utilizing this light intensity distribution within the liquid, we were able to generate a time-averaged non-vanishing Abraham force density, while simultaneously suppressing the Abraham-Minkowski force density. The incident laser field induced a linear axial displacement of the air-liquid interface inside the HOF, which provided a direct experimental measure of the Abraham force density. We find good agreement between the experimental results and theoretical determinations of the Abraham force density

  10. Precision measurement of the Casimir-Lifshitz force in a fluid

    CERN Document Server

    Munday, Jeremy N

    2007-01-01

    The Casimir force, which results from the confinement of the quantum mechanical zero-point fluctuations of the electromagnetic fields, has received significant attention in recent years for its effect on micro- and nano-scale mechanical systems. With few exceptions, experimental observations have been limited to conductive bodies interacting separated by vacuum or air. However, interesting phenomena including repulsive forces are expected to exist in certain circumstances between metals and dielectrics when the intervening medium is not vacuum. In order to better understand the effect of the Casimir force in such situations and to test the robustness of the generalized Casimir-Lifshitz theory, we have performed the first precision measurements of the Casimir force between two metals immersed in a fluid. For this situation, the measured force is attractive and is approximately 80% smaller than the force predicted by Casimir for ideal metals in vacuum. We present experimental results and find them to be consist...

  11. Human and other mammalian bite injuries of the hand: evaluation and management.

    Science.gov (United States)

    Kennedy, Stephen A; Stoll, Laura E; Lauder, Alexander S

    2015-01-01

    The hand is the most common site for bite injuries. Because of specific characteristics of hand anatomy, bite mechanics, and organisms found in human and animal saliva, even small wounds can lead to aggressive infections. Failure to recognize and treat hand bites can result in significant morbidity. Human and animal bites most commonly lead to polymicrobial bacterial infections with a mixture of aerobic and anaerobic organisms. Pasteurella species are commonly found in dog and cat bite wounds, and Eikenella is characteristic of human wounds. Staphylococcus, Streptococcus, and anaerobic bacterial species are common to all mammals. Although public health measures in developed countries have been highly effective at reducing rabies transmission, dog bites remain the most common source of rabies infection worldwide. Human bites can transmit HIV, hepatitis B, or hepatitis C, especially when contaminated blood is exposed to an open wound. Appropriate management of any mammal bite requires recognition, early wound cleansing, evaluation of injured structures, and infection prophylaxis. Structural repair is performed as indicated by the severity and contamination of the injury, and wounds may require delayed closure. Wound infections typically require débridement, empiric antibiotics, and delayed repair or reconstruction. PMID:25538130

  12. [Viper bite treatment in Spain].

    Science.gov (United States)

    Estefanía Díez, M; Alonso Peña, D; García Cano, P; López Gamo, A

    2016-01-01

    Viper snake bite is, by far, the most common ophidian accident in Spain. It is responsible for between 100 and 150 hospitalizations per year in this country, although it is difficult to determine the frequency of emergency admissions due to this cause. The cornerstone to their approach rests on the correct evaluation of the possible effects derived from envenomation and the use of anti-venoms. In spite of all the controversies surrounding the use of anti-venoms, they have become a powerful therapeutic weapon ever since the serum has been highly purified and the great decrease of related anaphylactic reactions. The aim of this article is to update the emergency room procedures when viper bites are suspected, and to clarify the main therapeutic recommendations. PMID:25440968

  13. Experimental Measurements of Hydrodynamic Radial Forces and Stiffness Matrices for a Centrifugal Pump-Impeller

    OpenAIRE

    Chamieh, Dmitri S.; Acosta, Allan J.; Brennen, Christopher E.; Caughey, Thomas K.

    1985-01-01

    The present work is an experimental investigation of the possible forces of fluid dynamic origin that can act on a turbomachine rotor particularly when it is situated off its normal center position. An experimental facility, the Rotor Force Test Facility, has been designed and contructed in order to measure these kinds of forces acting on a centrifugal pump impeller when the latter is made to whirl in a slightly eccentric circular orbit. The scope of the present experimental work consists o...

  14. Interrogating Biology with Force: Single Molecule High-Resolution Measurements with Optical Tweezers

    OpenAIRE

    Capitanio, Marco; Pavone, Francesco S.

    2013-01-01

    Single molecule force spectroscopy methods, such as optical and magnetic tweezers and atomic force microscopy, have opened up the possibility to study biological processes regulated by force, dynamics of structural conformations of proteins and nucleic acids, and load-dependent kinetics of molecular interactions. Among the various tools available today, optical tweezers have recently seen great progress in terms of spatial resolution, which now allows the measurement of atomic-scale conformat...

  15. A Noncontact Force Sensor Based on a Fiber Bragg Grating and Its Application for Corrosion Measurement

    OpenAIRE

    Antonio C. Bruno; Clara J. Pacheco

    2013-01-01

    A simple noncontact force sensor based on an optical fiber Bragg grating attached to a small magnet has been proposed and built. The sensor measures the force between the magnet and any ferromagnetic material placed within a few millimeters of the sensor. Maintaining the sensor at a constant standoff distance, material loss due to corrosion increases the distance between the magnet and the corroded surface, which decreases the magnetic force. This will decrease the strain in the optical fiber...

  16. Leptospirosis and an animal bite

    OpenAIRE

    Brenden A Bedard; Kennedy, Byron S.; Anita C Weimer; Anthony Petruso; Richard Magnussen

    2014-01-01

    In October 2013, leptospirosis was identified in a 20-year-old male. The male was bitten on his hand by either his canine or a skunk while breaking up a fight between the two animals. Eight days after the bite, the male developed fever, headache, drowsiness, neck pain, nausea, vomiting, diarrhea, malaise and erythematous rash. Diagnosis was confirmed by amplification of Leptospira by DNA from a urine specimen. Veterinarian serology testing of the canine for Leptospira was negative. Leptospira...

  17. Measurement of strut chordal forces of the tricuspid valve using miniature C ring transducers.

    Science.gov (United States)

    Troxler, Lauren G; Spinner, Erin M; Yoganathan, Ajit P

    2012-04-01

    Tricuspid valve (TV) leaflets, papillary muscles (PM), and tendinous chords must work together to ensure proper coaptation. Alterations in valvular mechanics, including chordal forces, may lead to improper coaptation resulting in tricuspid regurgitation. Little is known about TV mechanics as right-sided heart diseases have been overlooked. We sought to fill this gap by understanding the role of TV strut chords with the objective to understand how strut chordal force varies depending on papillary muscle (PM) origin and leaflet attachment in the normal state. Additionally we investigated how these forces are altered with abnormal geometry. Porcine TVs (n=18) were studied in a right-heart simulator capable of reproducing physiological and pathological conditions. Miniature force transducers were placed on strut chords to measure forces throughout the cardiac cycle. In the normal state, chordal force depended upon PM attachment in which chords branching from the septal PM (SPM) carried significantly less force compared to those branching from the anterior PM (APM) (p≤0.05). Annular dilatation resulted in significant increase in chordal force (p≤0.05) on all strut chords. Severe PM displacement led to increased chordal force in chords attaching the APM to the posterior leaflet as well as chords attaching the PPM to the septal leaflet. Elevated chordal force due to isolated annular dilatation was further increased only with addition of apical displacement of the APM. These results provide initial knowledge of TV chordal force mechanics and may be applied to future studies on TV repair techniques. PMID:22284427

  18. Insecticidal sugar baits for adult biting midges.

    Science.gov (United States)

    Snyder, D; Cernicchiaro, N; Allan, S A; Cohnstaedt, L W

    2016-06-01

    The mixing of an insecticide with sugar solution creates an oral toxin or insecticidal sugar bait (ISB) useful for reducing adult insect populations. The ability of ISBs to kill the biting midge Culicoides sonorensis Wirth and Jones (Diptera: Ceratopogonidae), a vector of bluetongue virus, epizootic hemorrhagic disease and vesicular stomatitis viruses, was tested. The commercial insecticide formulations (percentage active ingredient) tested included bifenthrin, cyfluthrin, deltamethrin, permethrin, dinotefuran, imidacloprid, thiamethoxam and spinosad. Mortality rates were determined for various concentrations of commercial formulations (0.01, 0.05, 0.1, 1, 2 and 3%) and observed at 1, 4, 10 and 24 h post-exposure to the ISB. In the first set of assays, laboratory-reared midges were fed sugar ad libitum and then exposed to insecticide-treated sugar solutions to measure mortality. The second assay assessed competitive feeding: midges were provided with a control sugar solution (10% sucrose) in one vial, and a sugar and insecticide solution in another. Pyrethroid treatments resulted in the greatest mortality in the first hour at the lowest concentrations and spinosad consumption resulted in the least mortality. Biting midges were not deterred from feeding on the 1% ISB solutions despite the presence of an insecticide-free alternative source of sugar. PMID:26789534

  19. 硬措施到底有多硬?%Are Forceful Measures Effective Indeed?

    Institute of Scientific and Technical Information of China (English)

    杜燕鹏

    2003-01-01

    In the “Interconnection Year”, a series of forceful measures are promulgated, aiming at solving the interconnection problems and regulating telecom market. All those measures show that the government and MII are paying great attention to regulation in telecom industry. Those forceful measures are expected to promote telecom industry reform, the competition in telecom market and the development of telecom industry. Then some questions may come into our mind. Are forceful measures effective or not? How to make them effective?…… In order to have a clear answer to those questions, in this issue =New Telecom Salon" focuses on the fulfilling of forceful measures. The specialists in the industry are invited to discuss aU related things about this subject.

  20. Time, tire measurements forces and moments: a new standard for steady state cornering tyre testing

    NARCIS (Netherlands)

    Oosten, J.J.M. van; Savi, C.; Augustin, M.; Bouhet, O.; Sommer, J.; Colinot, J.P.

    1999-01-01

    In order to develop vehicles which have maximum active safety, car manufacturers need information about the so-called force and moment properties of tyres. Vehicle manufacturers, tyre suppliers and automotive research organisations have advanced test equipment to measure the forces between a tyre an

  1. The application of magnetic force differentiation for the measurement of the affinity of peptide libraries

    International Nuclear Information System (INIS)

    A new method has been developed for measuring the binding affinity of phage displayed peptides and a target protein using magnetic particles. The specific interaction between the phage displayed peptides and the target protein was subject to a force generated by the magnetic particle. The binding affinity was obtained by analyzing the force-bond lifetime

  2. For whom the cells pull: Hydrogel and micropost devices for measuring traction forces.

    Science.gov (United States)

    Ribeiro, Alexandre J S; Denisin, Aleksandra K; Wilson, Robin E; Pruitt, Beth L

    2016-02-01

    While performing several functions, adherent cells deform their surrounding substrate via stable adhesions that connect the intracellular cytoskeleton to the extracellular matrix. The traction forces that deform the substrate are studied in mechanotrasduction because they are affected by the mechanics of the extracellular milieu. We review the development and application of two methods widely used to measure traction forces generated by cells on 2D substrates: (i) traction force microscopy with polyacrylamide hydrogels and (ii) calculation of traction forces with arrays of deformable microposts. Measuring forces with these methods relies on measuring substrate displacements and converting them into forces. We describe approaches to determine force from displacements and elaborate on the necessary experimental conditions for this type of analysis. We emphasize device fabrication, mechanical calibration of substrates and covalent attachment of extracellular matrix proteins to substrates as key features in the design of experiments to measure cell traction forces with polyacrylamide hydrogels or microposts. We also report the challenges and achievements in integrating these methods with platforms for the mechanical stimulation of adherent cells. The approaches described here will enable new studies to understand cell mechanical outputs as a function of mechanical inputs and advance the understanding of mechanotransduction mechanisms.

  3. Measurements of normal and frictional forces in a rolling process

    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Wanheim, Tarras

    2006-01-01

    To improve the quality of frictional data and to validate the simulations in rolling, a load transducer for measuring normal and frictional stresses in the deformation zone has been developed. The transducer consists of a strain-gauge-equipped insert embedded in the surface of the roll. The length...... between the transducer and roll. The transducer is tested at laboratory conditions and is expected to be running in industrial conditions in 2004....

  4. Measurements of Normal and Friction Forces in a Rolling Process

    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Wanheim, Tarras

    2004-01-01

    To improve the quality of frictional data and to validate the simulations in rolling, a load transducer for measuring normal and friction stresses in the deformation zone has been developed. The transducer consists of a strain gauge equipped insert embedded in the surface of the roll. The length...... between transducer and roll. The transducer is tested at laboratory conditions and is expected to be running in industrial conditions in 2004....

  5. Bites, stings, and rigors: clinical considerations in African operations.

    Science.gov (United States)

    Lynch, James H; Verlo, April R; Givens, Melissa L; Munoz, Cesar E

    2014-01-01

    The natural health threats in Africa pose daunting clinical challenges for any provider, as evidenced by the current Ebola epidemic in West Africa, but the threat is multiplied for the Special Operations provider on the continent who faces these challenges with limited resources and the tyranny of distance. The majority of operationally significant health risks can be mitigated by strict adherence to a comprehensive force health protection plan. The simplest, yet most effective, technique for preventing mosquito-borne diseases is the prevention of mosquito bites with repellent, bed nets, and appropriate clothing in addition to chemoprophylaxis. Some of the more likely or lethal infectious diseases encountered on the continent include malaria, Chikungunya, dengue, human immunodeficiency virus, and Ebola. Venomous snakes pose a particular challenge since the treatment can be as deadly as the injury. Providers supporting African operations should educate themselves on the clinical characteristics of possible envenomations in their area while promoting snake avoidance as the primary mitigation measure. To succeed in Africa, the Special Operations provider must consider how to meet these challenges in an environment where there may not be reliable evacuation, hospitalization, or logistics channels. PMID:25399379

  6. Micropipette suction for measuring piconewton forces of adhesion and tether formation from neutrophil membranes.

    OpenAIRE

    Shao, J Y; Hochmuth, R M

    1996-01-01

    A new method for measuring piconewton-scale forces that employs micropipette suction is presented here. Spherical cells or beads are used directly as force transducers, and forces as small as 10-20 pN can be imposed. When the transducer is stationary in the pipette, the force is simply the product of the suction pressure and the cross-sectional area of the pipette minus a small correction for the narrow gap that exists between the transducer and the pipette wall. When the transducer is moving...

  7. Design and Analysis of a Sensor System for Cutting Force Measurement in Machining Processes

    OpenAIRE

    Qiaokang Liang; Dan Zhang,; Gianmarc Coppola; Jianxu Mao; Wei Sun; Yaonan Wang; Yunjian Ge

    2016-01-01

    Multi-component force sensors have infiltrated a wide variety of automation products since the 1970s. However, one seldom finds full-component sensor systems available in the market for cutting force measurement in machine processes. In this paper, a new six-component sensor system with a compact monolithic elastic element (EE) is designed and developed to detect the tangential cutting forces Fx, Fy and Fz (i.e., forces along x-, y-, and z-axis) as well as the cutting moments Mx, My and Mz (i...

  8. Colored polydimethylsiloxane micropillar arrays for high throughput measurements of forces applied by genetic model organisms.

    Science.gov (United States)

    Khare, Siddharth M; Awasthi, Anjali; Venkataraman, V; Koushika, Sandhya P

    2015-01-01

    Measuring forces applied by multi-cellular organisms is valuable in investigating biomechanics of their locomotion. Several technologies have been developed to measure such forces, for example, strain gauges, micro-machined sensors, and calibrated cantilevers. We introduce an innovative combination of techniques as a high throughput screening tool to assess forces applied by multiple genetic model organisms. First, we fabricated colored Polydimethylsiloxane (PDMS) micropillars where the color enhances contrast making it easier to detect and track pillar displacement driven by the organism. Second, we developed a semi-automated graphical user interface to analyze the images for pillar displacement, thus reducing the analysis time for each animal to minutes. The addition of color reduced the Young's modulus of PDMS. Therefore, the dye-PDMS composite was characterized using Yeoh's hyperelastic model and the pillars were calibrated using a silicon based force sensor. We used our device to measure forces exerted by wild type and mutant Caenorhabditis elegans moving on an agarose surface. Wild type C. elegans exert an average force of ∼1 μN on an individual pillar and a total average force of ∼7.68 μN. We show that the middle of C. elegans exerts more force than its extremities. We find that C. elegans mutants with defective body wall muscles apply significantly lower force on individual pillars, while mutants defective in sensing externally applied mechanical forces still apply the same average force per pillar compared to wild type animals. Average forces applied per pillar are independent of the length, diameter, or cuticle stiffness of the animal. We also used the device to measure, for the first time, forces applied by Drosophila melanogaster larvae. Peristaltic waves occurred at 0.4 Hz applying an average force of ∼1.58 μN on a single pillar. Our colored microfluidic device along with its displacement tracking software allows us to measure forces

  9. Force measurement using strain-gauge balance in a shock tunnel with long test duration.

    Science.gov (United States)

    Wang, Yunpeng; Liu, Yunfeng; Luo, Changtong; Jiang, Zonglin

    2016-05-01

    Force tests were conducted at the long-duration-test shock tunnel JF12, which has been designed and built in the Institute of Mechanics, Chinese Academy of Sciences. The performance tests demonstrated that this facility is capable of reproducing a flow of dry air at Mach numbers from 5 to 9 at more than 100 ms test duration. Therefore, the traditional internal strain-gauge balance was considered for the force tests use in this large impulse facility. However, when the force tests are conducted in a shock tunnel, the inertial forces lead to low-frequency vibrations of the test model and its motion cannot be addressed through digital filtering because a sufficient number of cycles cannot be found during a shock tunnel run. The post-processing of the balance signal thus becomes extremely difficult when an averaging method is employed. Therefore, the force measurement encounters many problems in an impulse facility, particularly for large and heavy models. The objective of the present study is to develop pulse-type sting balance by using a strain-gauge sensor that can be applied in the force measurement of 100 ms test time, especially for the force test of the large-scale model. Different structures of the S-series (i.e., sting shaped balances) strain-gauge balance are proposed and designed, and the measuring elements are further optimized to overcome the difficulties encountered during the measurement of aerodynamic force in a shock tunnel. In addition, the force tests were conducted using two large-scale test models in JF12 and the S-series strain-gauge balances show good performance in the force measurements during the 100 ms test time. PMID:27250471

  10. Oscillatory and ion-correlation forces observed in direct force measurements between silica surfaces in concentrated CaCl2 solutions

    NARCIS (Netherlands)

    Fielden, ML; Hayes, RA; Ralston, J

    2000-01-01

    The force between silica spheres and naturally oxidised silicon wafer has been measured in calcium chloride solutions at concentrations between 1 and 5 M using an atomic force microscope. An oscillatory force, consistent in periodicity with the expulsion of layers of ions, was found to overlay the e

  11. Linear servo-controlled pressure generator for forced oscillation measurements.

    Science.gov (United States)

    de Melo, P L; Werneck, M M; Giannella-Neto, A

    1998-01-01

    In respiratory input impedance measurements, the low-frequency range contains important clinical and physiological information. However, the patient's spontaneous ventilation can contaminate the data in this range, leading to unreliable results. Unbiased estimators are a good alternative to overcome this problem, provided that the generator is considered linear. This condition is not fulfilled by most existing generators as they are based on loudspeakers, which have strong nonlinearities. The present work aims to contribute to the solution of this problem, and describes a pressure generator that minimises the nonlinearities by an optical sensor placed in a position feedback loop. The static evaluation shows a high linearity for the optical system. The well known frequency response of pressure transducers is used in the dynamic evaluation of the instrument. The analysis of the generator shows that the use of position feedback improved the frequency response. The total harmonic distortion (THD) measurement shows that closed loop resulted in an effective decrease in the nonlinearities. The reduction of THD achieved by the servo-controlled generator can contribute to the practical implementation of the unbiased estimators, increasing the reliability of the impedance data, especially in the low-frequency range. This system is compared with conventional generators and with another servo-controlled system.

  12. CLINICO EPIDEMIOLOGICAL PROFILE OF WILD ANIMAL BITE VICTIMS ATTENDING ANTI RABIES CLINIC AT GOVERNMENT TERTIARY CARE CENTRE IN MANDYA

    Directory of Open Access Journals (Sweden)

    Jahnavi

    2014-11-01

    Full Text Available : INTRODUCTION: Rabies is an acute viral disease that causes fatal encephalitis in virtually all the warm blooded animals including man. In India it is estimated that annually 17.4 million animal bite cases occur and 20, 000 deaths occur due to human rabies. Dogs are responsible for about 97%of the human rabies, followed by cats (2%, jackals, mongoose and others (1%. There is scarcity of literature regarding human rabies due to wild animals. OBJECTIVES: To describe the socio- demographic characteristics of wild animal bite victims attending Anti Rabies Clinic (ARC, Mandya Institute of Medical Sciences (MIMS, Mandya and to describe the circumstances, characteristics of bite and post exposure prophylactic measures taken to prevent rabies. METHODOLOGY: This hospital based case record analysis was done for a period of 3 years from January 2011 to December 2013 at Anti Rabies Clinic (ARC, Mandya Institute of Medical Sciences, Mandya. The details regarding the socio demographic characteristics of bite victims, characteristics of the bite wound and post exposure prophylactic measures taken to prevent rabies were collected using case records of wild animal bite victims. RESULTS: A total of 12, 798 animal bite victims had attended ARC during the study period, of which 67 (0.52% cases were exposed to wild animals. Of these 67 cases, 45 (67.2% of the victims were exposed to monkey and 13 (19.4% were exposed to wild boar. 45 (67.2% of the wild animal bite victims were in the age group of 15 to 60 years, 49 (73.1% were males and 22 (32.8% belonging to class IV socio economic status. Many of the monkey bites happened when the monkey was trying to snatch food from the victims and while other wild animal bites happened when the farmers were guarding their field. 40 (59.7% had bites on upper limb. 51 (76.1% had washed the wound with soap and water before coming to ARC. RIG was advised to all victims but was taken by 49 (73.1% of the bite victims. All four doses

  13. Measurement of Normal and Friction Forces in a Rolling Process

    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Wanheim, Tarras

    2004-01-01

    For the rolling process, knowledge about interface conditions is important since it directly influences the maximum reduction ratio and thereby the num-ber of steps required for a given reduction. The mechanical properties of the produced sheet and the surface quality of it are also influenced...... by the fric-tion conditions. To achieve this important informa-tion, measurements of the normal pressure and friction stresses in the deformation zone are re-quested. The direction of the friction stresses is changing during the rolling gap. At the entrance of the de-formation zone, the peripherical velocity...... of the roll is higher than for the incoming material, which causes frictional stresses at the material acting in the rolling direction. At the outlet of the rolling gap, the velocity of the deformed material exceeds the velocity of the roll, generating frictional stresses contrary to the direction of rolling...

  14. Direct measurements of controlled aerodynamic forces on a wire-suspended axisymmetric body

    Science.gov (United States)

    Abramson, Philip; Vukasinovic, Bojan; Glezer, Ari

    2011-06-01

    A novel in-line miniature force transducer is developed for direct measurements of the net aerodynamic forces and moments on a bluff body. The force transducers are integrated into each of the eight mounting wires that are utilized for suspension of an axisymmetric model in a wind tunnel having minimal wake interference. The aerodynamic forces and moments on the model are altered by induced active local attachment of the separated base flow. Fluidic control is effected by an array of four integrated aft-facing synthetic jet actuators that emanate from narrow, azimuthally segmented slots, equally distributed around the perimeter of the circular tail end. The jet orifices are embedded within a small backward-facing step that extends into a Coanda surface. The altered flow dynamics associated with both quasi-steady and transitory asymmetric activation of the flow control effect is characterized by direct force and PIV measurements.

  15. The influence of bite size and multiple bites on oral texture sensations

    NARCIS (Netherlands)

    Wijk, de R.A.; Engelen, L.; Prinz, J.F.; Weenen, H.

    2003-01-01

    The influence of bite size on sensory mouth- and afterfeel sensations was explored in two studies in which single bites of vanilla custard desserts were varied from 2 to 11 ml (study 1) and in which series of five bites of two different custard desserts were presented consecutively (study 2). In sin

  16. The influence of bite size and multiple bites on oral texture sensations

    NARCIS (Netherlands)

    Wijk, R.A. de; Engelen, L.; Prinz, J.F.; Weenen, H.

    2003-01-01

    The influence of bite size on sensory mouthfeel and afterfeel sensations was explored in two studies in which single bites of vanilla custard desserts were varied from 2 to 11 mL (study 1) and in which series of five bites of two different custard desserts were presented consecutively (study 2). In

  17. Sensitive measurement of forces at the micron scale using Bloch oscillations of ultracold atoms.

    Science.gov (United States)

    Carusotto, I; Pitaevskii, L; Stringari, S; Modugno, G; Inguscio, M

    2005-08-26

    We show that Bloch oscillations of ultracold fermionic atoms in the periodic potential of an optical lattice can be used for a sensitive measurement of forces at the micrometer length scale, e.g., in the vicinity of a dielectric surface. In particular, the proposed approach allows us to perform a local and direct measurement of the Casimir-Polder force which is, for realistic experimental parameters, as large as 10(-4) gravity.

  18. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM

    OpenAIRE

    Dongshi Guan; Zhi Hong Hang; Zsolt Marcet; Hui Liu; I. I. Kravchenko; Chan, C. T.; Chan, H. B.; Penger Tong

    2015-01-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optic...

  19. Possibility of non-invasive blood pressure estimation by measurements of force and arteries diameter

    OpenAIRE

    Veye, Florent; Mestre, Sandrine; Perez-Martin, Antonia; Triboulet, Jean

    2014-01-01

    International audience Ultrasound examination is the first line procedure for the diagnosis and follow-up of cardiovascular diseases. Instrumenting an ultrasound probe with a force sensor may improve the non-invasive measurement of arterial biomechanical parameters (diameter, pulsatility, intima-media thickness and flow-dependent dilation) by measuring and controlling the force exerted by the sonographer. We present here the results obtained with this approach coupled with image processing...

  20. Design and testing of an innovative measurement device for tyre-road contact forces

    Science.gov (United States)

    Cheli, F.; Braghin, F.; Brusarosco, M.; Mancosu, F.; Sabbioni, E.

    2011-08-01

    The measurement of tyre-road contact forces is the first step towards the development of new control systems for improving vehicle safety and performances. Tyre-road contact forces measurement systems are very expensive and significantly modify the unsprung masses of the vehicle as well as the rotational inertia of the tyres. Thus, vehicle dynamics results are significantly affected. As a consequence, the measured contact forces do not correspond to the contact forces under real working conditions. A new low-cost tyre-road contact forces measurement system is proposed in this paper that can be applied to passenger cars. Its working principle is based on the measurement of three deformations of the wheel rim through strain gauges. The tyre-rim assembly is thus turned into a sensor for tyre-road contact forces. The influence of the strain gauges position onto the measurement results has been assessed through finite element simulations and experimental tests. It has been proven that, for a large variety of rims, the strain gauge position that leads to high signal-to-noise ratios is almost the same. A dynamic calibration procedure has been developed in order to allow the reconstruction of contact force and torque components once per wheel turn. The capability of the developed device to correctly estimate tyre-road contact forces has been assessed, in a first stage, through indoor laboratory experimental test on an MTS Flat-Trac ® testing machine. Results show that the implemented measuring system allows to reconstruct contact forces once per wheel turn with a precision that is comparable to that of existing high-cost measurement systems. Subsequently, outdoor tests with a vehicle having all four wheels equipped with the developed measuring device have also been performed. Reliability of the measurements provided by the developed sensor has been assessed by comparing the global measured longitudinal/lateral forces and the product of the measured longitudinal

  1. Bug bites and stings: When to see a dermatologist

    Medline Plus

    Full Text Available ... Biting flies Mites Bees, wasps and hornets Spiders Ticks Fire ants Most bug bites and stings can ... red, donut-shaped rash that develops after a tick bite: This could be a sign of Lyme ...

  2. An Epidemiological Study of Animal Bites and Envenomings in a Rural District of Tamilnadu, India

    Directory of Open Access Journals (Sweden)

    Venkatesan M

    2014-12-01

    Full Text Available Aim: To find out the period prevalence of animal bites and envenomings, its epidemiological risk factors and treatment seeking behaviour. Materials and methods: The present cross sectional study was conducted in the 34 villages of the field practising areas of the Rural Health Training Centre, Thiruvenainallur. Considering the prevalence of bites as 7.4%, and taking 5 members in each household with a non response of 10% the number households studied were 4150 covering a population of 18865 which was calculated using an Open EPI version (2.3 software package. Sampling frame of households was prepared and systemic random sampling method was used to select households from each village. Trained medical interns and social workers collected information on bites in the preceding one year. Data was entered and analyzed in Epi_info (3.4.3 software. Results: In this study, information of 12947 adults was included and the overall period prevalence of bites was 81.8/1000 population. The most common bite is dog bite (22.3 followed by scorpion (22.1 and centipede (17.8 per 1000 population. The dog bites are significantly higher among males, people below the poverty line, farmers and laborers. There is significantly increased risk of snake bites among people working in agriculture fields. Only 35% of the dog bite victims washed their wound with soap and water and 28% applied irritants such as ash, ink, calotropis milk etc. over the wounds. Anti-rabies vaccination was given in 60% of the dog bite victims and life saving measure of Rabies Immunoglobulins (RIGS was given in only in 6.2%. Almost half of the bitten victims of scorpion and centipede follow traditional methods of treatment. Conclusions: Considering the high prevalence of different bites and treatment seeking behavior indicates there is a lack of awareness regarding all forms of bites in the rural community. The existing program of rabies control has to be strengthened and community awareness about

  3. Development and validation of system for measuring poling forces during Nordic walking

    Directory of Open Access Journals (Sweden)

    Jakub Krejčí

    2013-09-01

    Full Text Available BACKGROUND: Recently, the popularity of Nordic walking (NW has been rising steadily. Many scientific studies researched the promising and beneficial effects of this form of physical activity. However, only a few studies provided data about the forces acting on the poles. We did not find a commercially available system that enables the measurement of the poling forces. OBJECTIVE: The objective of this paper was to develop and validate a system for measuring the poling forces during NW. METHODS: Strain gauge force tranducers were mounted below the grips of standard NW poles. The transducer signals were amplified and converted to digital form for transmitting to a personal computer. Special software was developed for processing the measured data and the calculation method of output variables was described. Validation of the system was performed using a Kistler force plate. Poling cycles with peak force of about 150 N were imitated by pressing the pole over a force plate. RESULTS: A function sample of the measurement system was constructed. Validation yielded the mean absolute error of 1.1 N in case of poling cycles without pole impacts or 3.0 N in case of poling cycles with impacts. CONCLUSIONS: The validation result of our system is comparable to the results of similar systems used for measurements during cross-country skiing. The system enables independent measurement of the poling forces on both poles and the duration of measurement can be up to one hour. The system provides a tool that can be used to answer a number of questions that researches raise about NW. Understanding of the biomechanical and physiological aspects of poling action can constitute a scientific basis for promoting, teaching and training of NW.

  4. Pigs suffering from injurious behaviours like flank biting and tail biting are more interested to manipulate a novel rope than uninjured control animals

    NARCIS (Netherlands)

    Bracke, M.B.M.; Ettema, K.

    2014-01-01

    Injurious behaviours in pigs may involve persistent or forceful biting in specific body parts and may result in wounds of the pigs’ tails, ears, flanks and legs. Such behaviours, which may lead to progressive tissue damage, are difficult to counteract. On a commercial farm 22 groups of pigs with wou

  5. Measured and estimated ground reaction forces for multi-segment foot models.

    Science.gov (United States)

    Bruening, Dustin A; Cooney, Kevin M; Buczek, Frank L; Richards, James G

    2010-12-01

    Accurate measurement of ground reaction forces under discrete areas of the foot is important in the development of more advanced foot models, which can improve our understanding of foot and ankle function. To overcome current equipment limitations, a few investigators have proposed combining a pressure mat with a single force platform and using a proportionality assumption to estimate subarea shear forces and free moments. In this study, two adjacent force platforms were used to evaluate the accuracy of the proportionality assumption on a three segment foot model during normal gait. Seventeen right feet were tested using a targeted walking approach, isolating two separate joints: transverse tarsal and metatarsophalangeal. Root mean square (RMS) errors in shear forces up to 6% body weight (BW) were found using the proportionality assumption, with the highest errors (peak absolute errors up to 12% BW) occurring between the forefoot and toes in terminal stance. The hallux exerted a small braking force in opposition to the propulsive force of the forefoot, which was unaccounted for by the proportionality assumption. While the assumption may be suitable for specific applications (e.g. gait analysis models), it is important to understand that some information on foot function can be lost. The results help highlight possible limitations of the assumption. Measured ensemble average subarea shear forces during normal gait are also presented for the first time.

  6. Experimental measurements of hydrodynamic radial forces and stiffness matrices for a centrifugal pump-impeller

    Science.gov (United States)

    Chamieh, D. S.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1985-01-01

    Measurements of the steady-state hydrodynamic forces on a centrifugal pump impeller are presented as a function of position within two geometrically different volutes. These correspond to the forces experienced by the impeller at zero whirl frequency. The hydrodynamic force matrices derived from these measurements exhibit both diagonal and off-diagonal terms of substantial magnitude. These terms are of the form which would tend to excite a whirl motion in a rotordynamic analysis of the pump; this may be the cause of 'rough running' reported in many pumps. Static pressure measurements in the impeller discharge flow show that the hydrodynamic force on the impeller contains a substantial component due to the nonisotropy of the net momentum flux leaving the impeller. A similar breakdown of the contributions to the stiffness matrices reveals that the major component of these matrices results from the nonisotropy of the momentum flux.

  7. Use of force-measuring transducers in manipulator control. I - Theory. II - Implementation

    Science.gov (United States)

    Jansen, John; Kress, Reid

    Two types of control structures for teleoperated manipulators are investigated using force-measuring transducers with each type targeting specific properties of the manipulator. One approach is to measure torque in the drive train of the manipulator to increase backdriveability, sensitivity, and stiffness. The second is to measure the forces and torques at the wrist of the manipulator. This force/torque vector is then employed in a stiffness control algorithm which resolves dissimilar kinematics and increases sensitivity. It is shown that torque feedback can be used to reduce the apparent friction in a manipulator drive train caused by gear boxes, bearings, and transmissions. For teleoperated systems, drive-train torque feedback yields improved backdriveability, better sensitivity, and improved stiffness. Cartesian stiffness control allows the operator to specify the relationship between force and displacement in any direction at the manipulator end effector.

  8. Calibrated atomic force microscope measurements of vickers hardness indentations and tip production and characterisation for scanning tunelling microscope

    DEFF Research Database (Denmark)

    Jensen, Carsten P.

    Calibrated atomic force microscope measurements of vickers hardness indentations and tip production and characterisation for scanning tunelling microscope......Calibrated atomic force microscope measurements of vickers hardness indentations and tip production and characterisation for scanning tunelling microscope...

  9. Evaluation of a Blade Force Measurement System for a Vertical Axis Wind Turbine Using Load Cells

    OpenAIRE

    Morgan Rossander; Eduard Dyachuk; Senad Apelfröjd; Kristian Trolin; Anders Goude; Hans Bernhoff; Sandra Eriksson

    2015-01-01

    Unique blade force measurements on an open site straight-bladed vertical axis wind turbine have been performed. This paper presents a method for measuring the tangential and normal forces on a 12-kW vertical axis wind turbine prototype with a three-bladed H-rotor. Four single-axis load cells were installed in-between the hub and the support arms on one of the blades. The experimental setup, the measurement principle, together with the necessary control and measurement system are described. Th...

  10. Note: Direct force and ionic-current measurements on DNA in a nanocapillary

    Science.gov (United States)

    Otto, O.; Steinbock, L. J.; Wong, D. W.; Gornall, J. L.; Keyser, U. F.

    2011-08-01

    We have developed optical tweezers, with force measurements based on fast video tracking, for analysis and control of DNA translocation through nanocapillaries. Nanocapillaries are single-molecule biosensors with very similar characteristics to solid-state nanopores. Our novel experimental setup allows for ionic-current measurements in which the nanocapillary is oriented perpendicular to the trapping laser. Using video-based particle tracking, we are able to measure the position of DNA coated colloids at sub-millisecond resolution and in real-time. We present the first electrophoretic force and simultaneous ionic-current measurements of a single DNA molecule inside the orifice of a nanocapillary.

  11. Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

    Directory of Open Access Journals (Sweden)

    Luning Shi

    2014-01-01

    Full Text Available A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

  12. Afibrinogenemia following snake bite (Crotalus durissus terrificus

    Directory of Open Access Journals (Sweden)

    C. F. S. Amaral

    1988-08-01

    Full Text Available This paper reports two cases of afibrinogenemia with normal platelet count following Crotalus durissus terrificus, snake bite Both patients presented high output acute renal failure and case two also had increased blood levels of CPK and LDH compatible with the diagnosis of rhabdomyolysis. Case one was given an unknown amount of antivenom and was treated with epsilonaminocaproic acid and a fresh whole blood transfusion and showed recovery of the coagulation disturbance 40 hours following these measures. Case two was given an adequate amount of crotalide antivenom and the coagulation tests performed 12 hours later showed a normal partial thromboplastin time and fibrinogen 86 mg/100ml. Case one presented no haemorrhagic disturbances. Case two presented persistent bleeding following venopuncture and after removal of impetigo crust in the legs. Acute renal failure was treated conservatively and both patients were discharged from the hospital with recovery of the renal function.

  13. Animal Bites Epidemiology in Shahroud City

    Directory of Open Access Journals (Sweden)

    Mohammad Amiri

    Full Text Available Introduction: Rabies is an infectious central nervous system disease that infects all mammals and man. This study aimed at investigating the epidemiology of animal bites in Shahroud. Methods: In this deh1ive study all the data related to animal bite cases in shahroud in 2008-2009 were collected based on the data registration notebooks. Results: A total of 588 cases of animal bite were reported in 2008-2009 the majority of whom (82.1% were male. Of this total 35.7% were urban and 64.3% were rural. Just 2 of the cases were foreigners. The incidence rate of animal bite in the city was 159 (27% compared to 429 cases (73% in villages. Dogs and cats accounted for about 79.1% and 12.6% of the cases respectively. 12 cases were also wolf fox and Reynard bites. All cases have completed vaccination. In 82.3% of animal bites the biter was alive after 10 days and in 2% biters were dead and in 15.6% the biter reported invisible after 10 days. The incidence rate of animal bites in Shahroud was 246 in one hundred thousand. Conclusions: Animal bites are one of the most important problems of public health. Educational activities along with the promotion of out- organizing cooperation can play a significant role in controlling this problem

  14. Talking to Patients about Preventing Tick Bites

    Centers for Disease Control (CDC) Podcasts

    2012-02-14

    This podcast will help health care providers identify patients who are at increased risk of getting tick bites and provide these patients with tick bite prevention and removal tips.  Created: 2/14/2012 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/14/2012.

  15. Contact-flatted measurement of eye stiffness based on force-displacement relationship

    Science.gov (United States)

    Zhang, Jin; Ma, Jianguo; Zhang, Xueyong

    2011-12-01

    This paper presents a noninvasive approach in vivo measurement of eye stiffness based on a force-displacement relationship, which is based on a new contact-probe method of simultaneously measuring the static force and displacement. First, a simple spherical eye model is introduced for deriving analytical eye stiffness when a static force is applied to an eye. Next, a measurement system for simultaneously measuring force and displacement when a probe is pressed onto the eye is presented. Static eye stiffness is defined which based on the measured force-displacement relationship. A photoelectric probe transducer acts as displacement detector. A 16-bit single-chip microprocessor with E2PROM in the electronic circuit played the role of a nucleus, which stored the program instructions and the interrelated data. Laboratory experiments were carried out on a simulated eyeball connected to a hydraulic manometer to obtain intraocular pressure at different levels. The experimental results show that the measured eye stiffness nicely matches the analytical result.

  16. Comparison of the bite mark pattern and intercanine distance between humans and dogs

    Directory of Open Access Journals (Sweden)

    Bina Kashyap

    2015-01-01

    Full Text Available Background: Bite marks show uniqueness due to specific characteristics and arrangement of teeth, but when it comes to bite mark analysis, it is complicated by numerous factors such as animal bite, abuse etc., Humans and pet animals (dog bite marks analysis is by far the most demanding and complicated part of forensic dentistry. Aim: To analyze and compare bite marks of humans and the pet animals (dog using indirect method, so as to assess its usefulness and application in forensic odontology. Materials and Methods: 40 samples including 20 humans (10 males and 10 females and 20 dogs of different breed were included in the study. Bite registration of all the samples were obtained on modeling wax and intercanine distance were measured. Data were analyzed and results were tabulated. Results: Arch size and intercanine distance showed variable differences among humans and on average dogs showed more intercanine distance and arch size. Among dog breeds larger dogs showed larger variables when compared to smaller dogs. Conclusion: Assessment of bite marks evidences made by animals needs further investigation so that it can be a tool to assist the justice system to answer crucial questions.

  17. Prevention of crib-biting: a review.

    Science.gov (United States)

    McGreevy, P D; Nicol, C J

    1998-11-01

    Crib-biting is a common oral stereotype. Because of perceived deleterious effects on the health and appearance of subjects the prevention of crib-biting is regularly attempted. The resourcefulness of horses in satisfying their motivation to perform this behaviour often frustrates owners' efforts at prevention. This paper reviews the efficacy and observable consequences of attempting to prevent crib-biting by a variety of methods. These include attempts to prevent the grasping of objects, to interfere with air-engulfing and to introduce punishment for grasping and neck-flexion. Other approaches include the use of surgery, acupuncture, pharmaceuticals, operant feeding and environmental enrichment. A remedy that is effective for every crib-biter remains elusive. We conclude that, rather than concentrating on remedial prevention, further research should be directed at establishing why horses crib-bite and how the emergence of crib-biting can be avoided. PMID:10485002

  18. Soft colloidal probes for AFM force measurements between water droplets in oil

    KAUST Repository

    Vakarelski, Ivan Uriev

    2014-11-01

    Here we introduce an extension of the atomic force microscopy (AFM) colloidal probe technique, as a simple and reliable experimental approach to measure the interaction forces between small water droplets (~80-160. μm) dispersed in oil. Small water droplets are formed by capillary breakup of a microscale water jet in air, which is forced out of a fine capillary nozzle, and deposited on a superhydrophobic substrate immersed in tetradecane oil medium. In these conditions the water droplets are very loosely attached to the superhydrophobic substrate and are easily picked up with a hydrophobic AFM cantilever to form a soft colloidal probe. Sample force measurements are conducted to demonstrate the capability of the technique.

  19. Construction of force measuring optical tweezers instrumentation and investigations of biophysical properties of bacterial adhesion organelles

    CERN Document Server

    Andersson, Magnus

    2015-01-01

    Optical tweezers are a technique in which microscopic-sized particles, including living cells and bacteria, can be non-intrusively trapped with high accuracy solely using focused light. The technique has therefore become a powerful tool in the field of biophysics. Optical tweezers thereby provide outstanding manipulation possibilities of cells as well as semi-transparent materials, both non-invasively and non-destructively, in biological systems. In addition, optical tweezers can measure minute forces (< 10-12 N), probe molecular interactions and their energy landscapes, and apply both static and dynamic forces in biological systems in a controlled manner. The assessment of intermolecular forces with force measuring optical tweezers, and thereby the biomechanical structure of biological objects, has therefore considerably facilitated our understanding of interactions and structures of biological systems. Adhesive bacterial organelles, so called pili, mediate adhesion to host cells and are therefore crucial...

  20. Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM.

    Science.gov (United States)

    Zhang, Wen; Stack, Andrew G; Chen, Yongsheng

    2011-02-01

    To better understand environmental behaviors of nanoparticles (NPs), we used the atomic force microscopy (AFM) to measure interaction forces between E. coli cells and NPs immobilized on surfaces in an aqueous environment. The results showed that adhesion force strength was significantly influenced by particle size for both hematite (α-Fe(2)O(3)) and corundum (α-Al(2)O(3)) NPs whereas the effect on the repulsive force was not observed. The adhesion force decreased from 6.3±0.7nN to 0.8±0.4nN as hematite NPs increased from 26nm to 98nm in diameter. Corundum NPs exhibited a similar dependence of adhesion force on particle size. The Johnson-Kendall-Roberts (JKR) model was employed to estimate the contact area between E. coli cells and NPs, and based on the JKR model a new model that considers local effective contact area was developed. The prediction of the new model matched the size dependence of adhesion force in experimental results. Size effects on adhesion forces may originate from the difference in local effective contact areas as supported by our model. These findings provide fundamental information for interpreting the environmental behaviors and biological interactions of NPs, which barely have been addressed. PMID:20932723

  1. Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wen [Georgia Institute of Technology; Chen, Yongsheng [Georgia Institute of Technology

    2011-01-01

    To better understand environmental behaviors of nanoparticles (NPs), we used the atomic force microscopy (AFM) to measure interaction forces between E. coli cells and NPs immobilized on surfaces in an aqueous environment. The results showed that adhesion force strength was significantly influenced by particle size for both hematite ( -Fe2 O3 ) and corundum ( -Al2 O3 ) NPs whereas the effect on the repulsive force was not observed. The adhesion force decreased from 6.3 0.7 nN to 0.8 0.4 nN as hematite NPs increased from 26 nm to 98 nm in diameter. Corundum NPs exhibited a similar dependence of adhesion force on particle size. The Johnson Kendall Roberts (JKR) model was employed to estimate the contact area between E. coli cells and NPs, and based on the JKR model a new model that considers local effective contact area was developed. The prediction of the new model matched the size dependence of adhesion force in experimental results. Size effects on adhesion forces may originate from the difference in local effective contact areas as supported by our model. These findings provide fundamental information for interpreting the environmental behaviors and biological interactions of NPs, which barely have been addressed.

  2. Measurement of Breaking Force of Fluorescence Labelled Microtubules with Optical Tweezers

    Institute of Scientific and Technical Information of China (English)

    LIU Chun-Xiang; GUO Hong-Lian; XU Chun-Hua; YUAN Ming; LI Znao-Lin; CHENG Bing-Ying; ZHANG Dao-Zhong

    2005-01-01

    @@ Under illumination of excitation light, the force that can make fluorescent dye-labelled microtubules break up is measured by using dual-beam optical tweezers. It is found that this force is about several piconewtons, which is two orders of magnitude smaller than that without fluorescence label. Microtubules can be elongated about 20% and the increase of the tensile force is nonlinear with the microtubule elongation. Some qualitative explanations are given for the mechanisms about the breakup and elongation of microtubules exposed to excitation light.

  3. Aerodynamics of Dragonfly in Forward Flight: Force measurements and PIV results

    Science.gov (United States)

    Hu, Zheng; Deng, Xinyan

    2009-11-01

    We used a pair of dynamically scaled robotic dragonfly model wings to investigate the aerodynamic effects of wing-wing interaction in dragonflies. We follow the wing kinematics of real dragonflies in forward flight, while systematically varied the phase difference between the forewing and hindwing. Instantaneous aerodynamic forces and torques were measured on both wings, while flow visualization and PIV results were obtained. The results show that, in forward flight, wing-wing interaction always enhances the aerodynamic forces on the forewing through an upwash brought by the hindwing, while reduces the forces on the hindwing through a downwash brought by the forewing.

  4. Biting

    Science.gov (United States)

    ... to a more positive activity, like dancing to music, coloring, or playing a game. Punishment is usually ... a smaller setting. Find alternatives. As your child's language skills develop, you can help him or her ...

  5. Measurement of internal forces in superconducting accelerator magnets with strain gauge transducers

    International Nuclear Information System (INIS)

    An improved method has been developed for the measurement of internal forces in superconducting accelerator magnets, in particular the compressive stresses in coils and the end restraint forces on the coils. The transducers have been designed to provide improved sensitivity to purely mechanical strain by using bending mode deflections for sensing the applied loads. Strain gauge resistance measurements are made with a new system that eliminates sources of errors due to spurious resistance changes in interconnecting wiring and solder joints. The design of the transducers and their measurement system is presented along with a discussion of the method of compensation for thermal and magnetic effects, methods of calibration with typical calibration data, and measured effects in actual magnets of the thermal stress changes from cooldown and the Lorentz forces during magnet excitation

  6. Measurement of friction force between two mica surfaces with multiple beam interferometry

    Directory of Open Access Journals (Sweden)

    Jung J.C.

    2010-06-01

    Full Text Available Friction forces play a crucial role in the tribological behaviour of microcomponents and the application of MEMS products. It is necessary to develop a measurement system to understand and control the material characteristics. In this study, a microscopic measurement system based on multiple beam interferometry is developed to measure the friction force between two mica thin films. Some frictional behaviour between the two mica sheets in contact are reported. The evaluated shear strength of mica agrees well to the existing data. It is possible to use the developed system for micro-tribology study.

  7. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement

    OpenAIRE

    Yu Xie; Yunlei Zhou; Yuzi Lin; Lingyun Wang,; Wenming Xi

    2016-01-01

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real...

  8. Reply to Comment on "Influence of Noise on Force Measurements" [1012.5371

    OpenAIRE

    VOLPE, Giovanni; Helden, Laurent; Brettschneider, Thomas; Wehr, Jan; Bechinger, Clemens

    2011-01-01

    Having a priori knowledge of the force acting on a noisy system it is possible to solve the issue relative to the interpretation of multiplicative noise terms (aka Ito-Stratonovich dilemma). We experimentally show that for a Brownian particle the anti-Ito convention is correct. This permits us to reconcile force measurements based on the equilibrium distribution and on the drift velocity of a Brownian particle in a diffusion gradient.

  9. Spiral Defects in Motility Assays: A Measure of Motor Protein Force

    Science.gov (United States)

    Bourdieu, L.; Duke, T.; Elowitz, M. B.; Winkelmann, D. A.; Leibler, S.; Libchaber, A.

    1995-07-01

    In a commonly used motility assay, cytoskeletal filaments are observed as they glide over a surface coated with motor proteins. Defects in the motion frequently interrupt the flow of filaments. Examination of one such defect, in which a filament adopts a spiral form and rotates about a fixed point, provides a simple measure of the force exerted by the motor proteins. We demonstrate the universality of this approach by estimating the elementary forces of both myosin and kinesin.

  10. A Novel Integrated Multifunction Micro-Sensor for Three-Dimensional Micro-Force Measurements

    OpenAIRE

    Yafei Qin; Weizhong Wang; Yulong Zhao

    2012-01-01

    An integrated multifunction micro-sensor for three-dimensional micro-force precision measurement under different pressure and temperature conditions is introduced in this paper. The integrated sensor consists of three kinds of sensors: a three-dimensional micro-force sensor, an absolute pressure sensor and a temperature sensor. The integrated multifunction micro-sensor is fabricated on silicon wafers by micromachining technology. Different doping doses of boron ion, placement and structure of...

  11. Determination of critical current density in melt-processed HTS bulks from levitation force measurements

    OpenAIRE

    Kordyuk, A. A.; Nemoshkalenko, V.V.; Viznichenko, R. V.; Habisreuther, T.; Gawalek, W.

    1999-01-01

    A simple approach to describe the levitation force measurements on melt-processed HTS bulks was developed. A couple of methods to determine the critical current density $J_c$ were introduced. The averaged $ab$-plane $J_c$ values for the field parallel to this plane were determined. The first and second levitation force hysteresis loops calculated with these $J_c$ values coincide remarkably well with the experimental data.

  12. Measuring the Elasticity of Clathrin-Coated Vesicles via Atomic Force Microscopy

    OpenAIRE

    Jin, Albert J.; Prasad, Kondury; Smith, Paul D.; Lafer, Eileen M.; Nossal, Ralph

    2006-01-01

    Using a new scheme based on atomic force microscopy (AFM), we investigate mechanical properties of clathrin-coated vesicles (CCVs). CCVs are multicomponent protein and lipid complexes of ∼100 nm diameter that are implicated in many essential cell-trafficking processes. Our AFM imaging resolves clathrin lattice polygons and provides height deformation in quantitative response to AFM-substrate compression force. We model CCVs as multilayered elastic spherical shells and, from AFM measurements, ...

  13. Extraction of the Solvation Structure on a Solid Plate from a force curve measured by Surface Force Apparatus in a hard-sphere fluid

    CERN Document Server

    Amano, Ken-ich

    2013-01-01

    Surface force apparatus (SFA) has been utilized to measure the force between arbitrary two surfaces in a solvent. Since the measured force curve contains the solvation force between the two surfaces, there is the oscillation period which corresponds to the diameter of the solvent particle in the force curve. Although the force curve contains information about the intrinsic solvation structure on the one solid plate, a method for extracting the intrinsic solvation structure has not been elucidated for a long time. Thus, in the present paper, we propose the extracting method based on the statistical mechanics of liquids. As a first step, we derive an equation for the extraction in a hard-sphere fluid.

  14. Measurement of attractive forces between single aerogel powder particles and the correlation with powder flow

    Energy Technology Data Exchange (ETDEWEB)

    Weth, M.; Kuhn, J.; Fricke, J. [Bavarian Center for Applied Energy Research, ZAE Bayern, Am Hubland, 97074 Wuerzburg (Germany); Hofmann, M. [Experimentelle Zahnmedizin EZM, Universitaet Wuerzburg, Am Pleicherwall 2, 97070 Wuerzburg (Germany)

    2001-06-01

    An atomic force microscope (AFM), which allows the measurement of forces as low as one tenth of a nano-Newton, was used to determine the attractive forces between single silica aerogel powder particles (100{mu}m diameter) under two different atmospheric conditions. Forces on the order of 10 nN were found to depend mainly on the contact geometry and thus on the surface structure of the powder particles. In a second series of experiments, the surface structure of the silica aerogel powder particles was characterized using the AFM. Smooth surface areas, several micrometers in size, are separated by cliffs and cracks. For comparison, the same measurements were made with precipitated silica powder. Here larger forces and a different surface structure were found. The structure of precipitated silica particles is spheroidal with bumps on it, which are some hundred nanometers in size. In addition to the AFM measurements, powder flow rate from a hopper was measured. The flow of powders depends on the surface structure but also on the atmospheric conditions (e.g. moist atmosphere or vacuum). In contrast to precipitated silica powder, silica aerogel powder showed a significantly higher flow rate under vacuum than in moist air.

  15. Static and dynamic force/moment measurements in the Eidetics water tunnel

    Science.gov (United States)

    Suarez, Carlos J.; Malcolm, Gerald N.

    1994-01-01

    Water tunnels have been utilized in one form or another to explore fluid mechanics and aerodynamics phenomena since the days of Leonardo da Vinci. Water tunnel testing is attractive because of the relatively low cost and quick turn-around time to perform flow visualization experiments and evaluate the results. The principal limitation of a water tunnel is that the low flow speed, which provides for detailed visualization, also results in very small hydrodynamic (aerodynamic) forces on the model, which, in the past, have proven to be difficult to measure accurately. However, the advent of semi-conductor strain gage technology and devices associated with data acquisition such as low-noise amplifiers, electronic filters, and digital recording have made accurate measurements of very low strain levels feasible. The principal objective of this research effort was to develop a multi-component strain gage balance to measure forces and moments on models tested in flow visualization water tunnels. A balance was designed that allows measuring normal and side forces, and pitching, yawing and rolling moments (no axial force). The balance mounts internally in the model and is used in a manner typical of wind tunnel balances. The key differences between a water tunnel balance and a wind tunnel balance are the requirement for very high sensitivity since the loads are very low (typical normal force is 0.2 lbs), the need for water proofing the gage elements, and the small size required to fit into typical water tunnel models.

  16. TheraBite exercises to treat trismus secondary to head and neck cancer

    OpenAIRE

    Kamstra, Jolanda I.; Roodenburg, Jan L. N.; Beurskens, Carien H. G.; Reintsema, Harry; Pieter U Dijkstra

    2013-01-01

    The aim of this study was to evaluate the effect of TheraBite exercises on mouth opening and to analyze factors influencing this effect in a patient record evaluation. Effect of exercises with a TheraBite to treat trismus was evaluated in 69 head and neck cancer patients of two university medical centers. Mouth opening was measured as interincisal distance in millimeters. Patient, tumor, and treatment characteristics were analyzed for their relationship with change in mouth opening. Variables...

  17. Quantitative measurements of electromechanical response with a combined optical beam and interferometric atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Labuda, Aleksander; Proksch, Roger [Asylum Research an Oxford Instruments Company, Santa Barbara, California 93117 (United States)

    2015-06-22

    An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever. The OBD method is easy to implement, has impressive noise performance, and tends to be mechanically robust. However, it represents an indirect measurement of the cantilever displacement, since it is fundamentally an angular rather than a displacement measurement. Here, we demonstrate a metrological AFM that combines an OBD sensor with a laser Doppler vibrometer (LDV) to enable accurate measurements of the cantilever velocity and displacement. The OBD/LDV AFM allows a host of quantitative measurements to be performed, including in-situ measurements of cantilever oscillation modes in piezoresponse force microscopy. As an example application, we demonstrate how this instrument can be used for accurate quantification of piezoelectric sensitivity—a longstanding goal in the electromechanical community.

  18. Mechanostimulation, electrostimulation and force measurement in an in vitro model of the isolated rat diaphragm

    International Nuclear Information System (INIS)

    In an in vitro model of the entire rat diaphragm, diaphragmatic contraction forces at defined preload levels were investigated. A total of 24 excised rat diaphragms were electrically stimulated inside a two-chamber strain-applicator. The resulting contraction forces were determined on eight adjusted preload levels via measuring the elicited pressure in the chamber below the diaphragm. Subsequently, diaphragms were exposed for 6 h to one of four treatments: (1) control, (2) cyclic mechanical stretch, (3) intermittent electrical stimulation or (4) combination of cyclic mechanical stretch and electrical stimulation. Diaphragmatic contraction force increased from 116 ± 21 mN at the lowest preload level to 775 ± 85 mN at the maximal preload level. After 6 h maximal muscle contraction forces were smallest after non-electrostimulated treatment (control: 81 ± 15 mN, mechanical deflection: 94 ± 12 mN) and largest after electrostimulation treatment (mere electrostimulation: 165 ± 20 mN, combined mechano- and electro-stimulation: 164 ± 14 mN). We conclude that our model allows force measurements on isolated rat diaphragms. Furthermore, we conclude that by intermediate electrical stimulation diaphragmatic force generation was better preserved than by mechanical stimulation

  19. Radiation force on absorbing targets and power measurements of a high intensity focused ultrasound (HIFU) source

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the analytic expressions for the radiated field of a circular concave piston given by Hasegawa et al.,an integral for calculation of the radiation force on a plane absorbing target in a spherically focused field is derived.A general relation between acoustic power P and normal radiation force Fn is obtained under the condition of kr 1.Numerical computation is carried out by using the symbolic computation program for practically focused sources and absorbing circular targets.The results show that,for a given source,there is a range of target positions where the radiation force is independent of the target’s position under the assumption that the contribution of the acoustic field behind the target to the radiation force can be neglected.The experiments are carried out and confirm that there is a range of target positions where the measured radiation force is basically independent of the target’s position even at high acoustic power (up to 700 W).It is believed that when the radiation force method is used to measure the acoustic power radiated from a focused source,the size of the target must be selected in such a way that no observable sound can be found in the region behind the target.

  20. Experimental validation of atomic force microscopy-based cell elasticity measurements

    Science.gov (United States)

    Harris, Andrew R.; Charras, G. T.

    2011-08-01

    Atomic force microscopy (AFM) is widely used for measuring the elasticity of living cells yielding values ranging from 100 Pa to 100 kPa, much larger than those obtained using bead-tracking microrheology or micropipette aspiration (100-500 Pa). AFM elasticity measurements appear dependent on tip geometry with pyramidal tips yielding elasticities 2-3 fold larger than spherical tips, an effect generally attributed to the larger contact area of spherical tips. In AFM elasticity measurements, experimental force-indentation curves are analyzed using contact mechanics models that infer the tip-cell contact area from the tip geometry and indentation depth. The validity of these assumptions has never been verified. Here we utilize combined AFM-confocal microscopy of epithelial cells expressing a GFP-tagged membrane marker to directly characterize the indentation geometry and measure the indentation depth. Comparison with data derived from AFM force-indentation curves showed that the experimentally measured contact area for spherical tips agrees well with predicted values, whereas for pyramidal tips, the contact area can be grossly underestimated at forces larger than ~ 0.2 nN leading to a greater than two-fold overestimation of elasticity. These data suggest that a re-examination of absolute cellular elasticities reported in the literature may be necessary and we suggest guidelines for avoiding elasticity measurement artefacts introduced by extraneous cantilever-cell contact.

  1. Experimental validation of atomic force microscopy-based cell elasticity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Andrew R; Charras, G T, E-mail: g.charras@ucl.ac.uk [London Centre for Nanotechnology, University College London, London WC1H 0AH (United Kingdom)

    2011-08-26

    Atomic force microscopy (AFM) is widely used for measuring the elasticity of living cells yielding values ranging from 100 Pa to 100 kPa, much larger than those obtained using bead-tracking microrheology or micropipette aspiration (100-500 Pa). AFM elasticity measurements appear dependent on tip geometry with pyramidal tips yielding elasticities 2-3 fold larger than spherical tips, an effect generally attributed to the larger contact area of spherical tips. In AFM elasticity measurements, experimental force-indentation curves are analyzed using contact mechanics models that infer the tip-cell contact area from the tip geometry and indentation depth. The validity of these assumptions has never been verified. Here we utilize combined AFM-confocal microscopy of epithelial cells expressing a GFP-tagged membrane marker to directly characterize the indentation geometry and measure the indentation depth. Comparison with data derived from AFM force-indentation curves showed that the experimentally measured contact area for spherical tips agrees well with predicted values, whereas for pyramidal tips, the contact area can be grossly underestimated at forces larger than {approx} 0.2 nN leading to a greater than two-fold overestimation of elasticity. These data suggest that a re-examination of absolute cellular elasticities reported in the literature may be necessary and we suggest guidelines for avoiding elasticity measurement artefacts introduced by extraneous cantilever-cell contact.

  2. The indirect measurement of biomechanical forces in the moving human body

    Science.gov (United States)

    Cluss, Melanie; Laws, Kenneth; Martin, Natalie; Nowicki, T. Scott; Mira, Allan

    2006-02-01

    Inexpensive experimental techniques now exist for indirectly measuring forces within the moving human body. These techniques involve nontrivial applications of basic physical principles, have practical uses, and are appropriate for undergraduate experimentation. A two-dimensional video motion analysis is used to find the accelerations of various parts of the body, and anatomical geometry is used to determine specific biomechanical forces and torques. The simple movement of a dancer landing from a vertical jump is analyzed through the use of a theoretical model of the leg to find the forces in the tendons attached to the knee. It is shown that these forces can be sufficiently large to lead to injury if jumps are performed repetitively.

  3. Measurements and analysis of force and moment of caudal fin model in C-start

    Institute of Scientific and Technical Information of China (English)

    ZHAO Liang; JING Jun; LU Xiyun; YIN Xiezhen

    2006-01-01

    The unsteady hydrodynamic forces and moments acting on caudal-fin models of fish with different shapes and different swing durations were experimentally measured to simulate the fish C-starts. The motion of models was characterized by rotating the model to a maximum deflection angle in an excursion time Tu and back to the initial position in a return time Td around its root-axis. Studies show that the caudal-fin plays an important role in fish C-starts and the caudal-fins with different shapes and different swing durations generate different forces and moments. In addition, the hydrodynamic forces and moments acting on the models with different shapes can be normalized by the 2nd and 3rd moments of area, respectively. The forces and moments acting on the models with different swing durations, but the same ratio of Tu to Td can also be scaled.

  4. Sliding mode-based lateral vehicle dynamics control using tyre force measurements

    Science.gov (United States)

    Kunnappillil Madhusudhanan, Anil; Corno, Matteo; Holweg, Edward

    2015-11-01

    In this work, a lateral vehicle dynamics control based on tyre force measurements is proposed. Most of the lateral vehicle dynamics control schemes are based on yaw rate whereas tyre forces are the most important variables in vehicle dynamics as tyres are the only contact points between the vehicle and road. In the proposed method, active front steering is employed to uniformly distribute the required lateral force among the front left and right tyres. The force distribution is quantified through the tyre utilisation coefficients. In order to address the nonlinearities and uncertainties of the vehicle model, a gain scheduling sliding-mode control technique is used. In addition to stabilising the lateral dynamics, the proposed controller is able to maintain maximum lateral acceleration. The proposed method is tested and validated on a multi-body vehicle simulator.

  5. Measurements on hydrophobic and hydrophilic surfaces using a porous gamma alumina nanoparticle aggregate mounted on Atomic Force Microscopy cantilevers

    NARCIS (Netherlands)

    Das, Theerthankar; Becker, Thomas; Nair, Balagopal N.

    2010-01-01

    Atomic Force Microscopy (AFM) measurements are extensively used for a detailed understanding of molecular and surface forces. In this study, we present a technique for measuring such forces, using an AFM cantilever attached with a porous gamma alumina nanoparticle aggregate. The modified cantilever

  6. Thermophoretic forces on DNA measured with a single-molecule spring balance

    DEFF Research Database (Denmark)

    Pedersen, Jonas Nyvold; Lüscher, Christopher James; Marie, Rodolphe;

    2014-01-01

    We stretch a single DNA molecule with thermophoretic forces and measure these forces with a spring balance: the DNA molecule itself. It is an entropic spring which we calibrate, using as a benchmark its Brownian motion in the nanochannel that contains and prestretches it. This direct measurement of...... contour length. We find the Soret coefficient per unit length of DNA at various ionic strengths. It agrees, with novel precision, with results obtained in bulk for DNA too short to shield itself and with the thermodynamic model of thermophoresis....

  7. A method to measure the nonlinear force caused emittance growth in a RF photoinjector

    Institute of Scientific and Technical Information of China (English)

    Li Zheng-Hong; Yang Zhen-Ping

    2006-01-01

    Based on the multi-slit method, a new method is introduced to measure the non linear force caused emittance growth in a RF photoinjector. It is possible to reconstruct the phase space of a beam under some conditions by the multi-slit method. Based on the reconstructed phase space, besides the emittance, the emittance growth from the distortion of the phase space can also be measured. The emittance growth results from the effects of nonlinear force acting on electron, which is very important for the high quality beam in a RF photoinjector.

  8. Temperature-dependent intermolecular force measurement of poly(N-isopropylacrylamide) grafted surface with protein.

    Science.gov (United States)

    Cho, Eun Chul; Kim, Yong Deuk; Cho, Kilwon

    2005-06-15

    We have investigated the temperature dependence of the intermolecular force between poly(N-isopropylacrylamide) (PNiPAM) grafted surface and bovine serum albumin (BSA) in phosphate buffer (pH 7.4) using atomic force microscopy at the nanonewton scale. These observations show that the interaction force is nearly zero below the phase transition temperature of PNiPAM and that it increases steeply during the phase transition. Since the PNiPAM chains are grafted onto the aminosilane (gamma-aminopropyltriethoxysilane)-treated silicon wafer, we measured the force-distance curve of BSA-immobilized tips for the bare and the aminosilane-treated silicon wafer. These surfaces show no temperature dependence and their values are different from those of the PNiPAM-grafted surfaces at 30 degrees C. The results indicate that the measured adhesion force is between the PNiPAM-grafted surface and the BSA-immobilized tip. Our studies on the intermolecular force between other surfaces (CH(3)- and COOH-terminated self-assembled monolayers) and the BSA-immobilized tip indicate that the variation in the intermolecular force between the PNiPAM surface and BSA with temperature can be attributed to the changes in the properties of the PNiPAM chains. From consideration of the PNiPAM phase transition mechanism, it is speculated that the intermolecular force between the PNiPAM-grafted surface and BSA would be affected by changes in the arrangement of the bound water molecules around the PNiPAM chain and by changes in the conformation (i.e., in the chain mobility) of the PNiPAM chain during the phase transition. PMID:15897061

  9. Prospective medical evaluation of 7 dogs presented with fly biting

    OpenAIRE

    Frank, Diane; Bélanger, Marie C.; Bécuwe-Bonnet, Véronique; Parent, Joane

    2012-01-01

    Fly biting describes a syndrome in which dogs appear to be watching something and then snapping at it. Medical work-up of fly biting in dogs has never been reported. The aims of this case series were to characterize fly biting and perform a complete medical evaluation of dogs displaying fly biting.

  10. Factors identifying pigs predisposed to tail biting

    OpenAIRE

    Beattie, V. E.; Breuer, K.; O Connell, N. E.; Sneddon, I. A.; Mercer, J. T.; Rance, K. A.; Sutcliffe, M. E. M.; Edwards, S A

    2005-01-01

    Approximately 5% of pigs slaughtered in the UK have been tail-bitten, leading to welfare and production issues. Tail biting is sporadic and not all pigs tail bite. The aim of this study was to identify factors that are common in pigs that perform tail-biting behaviour, and that might be used in a predictive way to identify such animals. The behaviour of 159 pigs was observed in the post-weaning period. Pigs were weaned at 4 weeks of age. In the week prior to weaning and at 6 weeks of age each...

  11. Statistical Analysis of Long- and Short-Range Forces Involved in Bacterial Adhesion to Substratum Surfaces as Measured Using Atomic Force Microscopy

    NARCIS (Netherlands)

    Chen, Yun; Busscher, Henk J.; van der Mei, Henny C.; Norde, Willem

    2011-01-01

    Surface thermodynamic analyses of microbial adhesion using measured contact angles on solid substrata and microbial cell surfaces are widely employed to determine the nature of the adhesion forces, i.e., the interplay between Lifshitz-van der Waals and acid-base forces. While surface thermodynamic a

  12. Investigating the adsorption of the gemini surfactant "12-2-12" onto mica using atomic force microscopy and surface force apparatus measurements

    NARCIS (Netherlands)

    Fielden, ML; Claesson, PM; Verrall, RE

    1999-01-01

    The adsorption of the cationic gemini surfactant 1,2-bis(n-dodecyldimethylammonium)ethane dibromide on mica was followed by measuring forces between mica surfaces and by atomic force microscopy (AFM) imaging. The surface charge was found to be neutralized at total surfactant concentrations between 8

  13. Statistical analysis of long- and short-range forces involved in bacterial adhesion to substratum surfaces as measured using atomic force microscopy.

    Science.gov (United States)

    Chen, Yun; Busscher, Henk J; van der Mei, Henny C; Norde, Willem

    2011-08-01

    Surface thermodynamic analyses of microbial adhesion using measured contact angles on solid substrata and microbial cell surfaces are widely employed to determine the nature of the adhesion forces, i.e., the interplay between Lifshitz-van der Waals and acid-base forces. While surface thermodynamic analyses are often viewed critically, atomic force microscopy (AFM) can also provide information on the nature of the adhesion forces by means of Poisson analysis of the measured forces. This review first presents a description of Poisson analysis and its underlying assumptions. The data available from the literature for different combinations of bacterial strains and substrata are then summarized, leading to the conclusion that bacterial adhesion to surfaces is generally dominated by short-range, attractive acid-base interactions, in combination with long-range, weaker Lifshitz-van der Waals forces. This is in line with the findings of surface thermodynamic analyses of bacterial adhesion. Comparison with single-molecule ligand-receptor forces from the literature suggests that the short-range-force contribution from Poisson analysis involves a discrete adhesive bacterial cell surface site rather than a single molecular force. The adhesion force arising from these cell surface sites and the number of sites available may differ from strain to strain. Force spectroscopy, however, involves the tedious task of identifying the minor peaks in the AFM retraction force-distance curve. This step can be avoided by carrying out Poisson analysis on the work of adhesion, which can also be derived from retraction force-distance curves. This newly proposed way of performing Poisson analysis confirms that multiple molecular bonds, rather than a single molecular bond, contribute to a discrete adhesive bacterial cell surface site. PMID:21642399

  14. Improved dynamic compensation for accurate cutting force measurements in milling applications

    Science.gov (United States)

    Scippa, A.; Sallese, L.; Grossi, N.; Campatelli, G.

    2015-03-01

    Accurate cutting-force measurements appear to be the key information in most of the machining related studies as they are fundamental in understanding the cutting processes, optimizing the cutting operations and evaluating the presence of instabilities that could affect the effectiveness of cutting processes. A variety of specifically designed transducers are commercially available nowadays and many different approaches in measuring cutting forces are presented in literature. The available transducers, though, express some limitations since they are conditioned by the vibration of the surrounding system and by the transducer's natural frequency. These parameters can drastically affect the measurement accuracy in some cases; hence an effective and accurate tool is required to compensate those dynamically induced errors in cutting force measurements. This work is aimed at developing and testing a compensation technique based on Kalman filter estimator. Two different approaches named "band-fitting" and "parallel elaboration" methods, have been developed to extend applications of this compensation technique, especially for milling purpose. The compensation filter has been designed upon the experimentally identified system's dynamic and its accuracy and effectiveness has been evaluated by numerical and experimental tests. Finally its specific application in cutting force measurements compensation is described.

  15. Lorentz force sigmometry: a novel technique for measuring the electrical conductivity of solid and liquid metals

    International Nuclear Information System (INIS)

    In this paper, a novel method to measure the electrical conductivity of solid and molten metals is described. We term the method ‘Lorentz force sigmometry’, where the term ‘sigmometry’ refers to the letter sigma σ, often used to denote the electrical conductivity. The Lorentz force sigmometry method is based on the phenomenon of eddy currents generation in a moving conductor exposed to a magnetic field. Based on Ampere’s law, the eddy currents in turn generate a secondary magnetic field; as a result, the Lorentz force acts to brake the conductor. Owing to Newton’s third law, a measurable force, which is equal to the Lorentz force and is directly proportional to the electrical conductivity of the conductive fluid or solid, acts on the magnet. We present the results of the measurements performed on solids along with the initial measurements on fluids with a eutectic alloy composition of Ga67In20.5Sn12.5; detailed measurements on molten metals are still in progress and will be published in the future. We conducted a series of experiments and measured the properties of known electrical conductive metals, including aluminum and copper, to compute the calibration factor of the device, and then used the same calibration factor to estimate the unknown electrical conductivity of a brass bar. The predicted electrical conductivity of the brass bar was compared with the conductivity measured with a commercial device called ‘SigmaTest’; the observed error was less than 0.5%. (paper)

  16. Awareness of rabies and response to dog bites in a Bangladesh community

    DEFF Research Database (Denmark)

    Ghosh, Sumon; Chowdhury, Sukanta; Haider, Najmul;

    2016-01-01

    Community awareness regarding rabies and treatment seeking behaviours are critical both for the prevention and control of the disease in human and animals. We conducted a study to explore people's awareness about rabies, their attitudes towards dogs and practices associated with treating dog bites...... or feeding a community dog (OR: 2.1, 95% CI: 1.4–2.9) showed an increased risk of getting a dog bite. Among the bite victims, 3.6% (n = 6) humans and 15.8% (n = 60) animals died. As a measure for dog population management (DPM), 56% preferred sterilization while the rest preferred killing of dogs...... in Satkhira Sadar, a south-western sub-district of Bangladesh. Of the total 3200 households (HHs) surveyed, the majority of the respondents have heard about rabies (73%) and there was a high level of awareness that dog bite is the main cause of rabies (86%), and that rabies can be prevented by vaccination (85...

  17. Pain and instability during biting with mandibular implant-retained overdentures

    NARCIS (Netherlands)

    Fontijn-Tekamp, FA; Slagter, AP; van't Hof, MA; Kalk, W; Jansen, JA

    2001-01-01

    We tested in a randomized controlled clinical trial the effect of pain and instability of dentures on bite force with different degrees of mucosal support. The trial involved 3 groups who had received: 1) a new conventional denture (CD-group), 2) an implant-mucosa-borne overdenture on 2 IMZ implants

  18. A Noncontact Force Sensor Based on a Fiber Bragg Grating and Its Application for Corrosion Measurement

    Directory of Open Access Journals (Sweden)

    Antonio C. Bruno

    2013-08-01

    Full Text Available A simple noncontact force sensor based on an optical fiber Bragg grating attached to a small magnet has been proposed and built. The sensor measures the force between the magnet and any ferromagnetic material placed within a few millimeters of the sensor. Maintaining the sensor at a constant standoff distance, material loss due to corrosion increases the distance between the magnet and the corroded surface, which decreases the magnetic force. This will decrease the strain in the optical fiber shifting the reflected Bragg wavelength. The measured shift for the optical fiber used was 1.36 nm per Newton. Models were developed to optimize the magnet geometry for a specific sensor standoff distance and for particular corrosion pit depths. The sensor was able to detect corrosion pits on a fuel storage tank bottom with depths in the sub-millimeter range.

  19. Force sensing using 3D displacement measurements in linear elastic bodies

    Science.gov (United States)

    Feng, Xinzeng; Hui, Chung-Yuen

    2016-07-01

    In cell traction microscopy, the mechanical forces exerted by a cell on its environment is usually determined from experimentally measured displacement by solving an inverse problem in elasticity. In this paper, an innovative numerical method is proposed which finds the "optimal" traction to the inverse problem. When sufficient regularization is applied, we demonstrate that the proposed method significantly improves the widely used approach using Green's functions. Motivated by real cell experiments, the equilibrium condition of a slowly migrating cell is imposed as a set of equality constraints on the unknown traction. Our validation benchmarks demonstrate that the numeric solution to the constrained inverse problem well recovers the actual traction when the optimal regularization parameter is used. The proposed method can thus be applied to study general force sensing problems, which utilize displacement measurements to sense inaccessible forces in linear elastic bodies with a priori constraints.

  20. [Methodology and Implementation of Forced Oscillation Technique for Respiratory Mechanics Measurement].

    Science.gov (United States)

    Zhang, Zhengbo; Ni, Lu; Liu, Xiaoli; Li, Deyu; Wang, Weidong

    2015-11-01

    The forced oscillation technique (FOT) is a noninvasive method for respiratory mechanics measurement. For the FOT, external signals (e.g. forced oscillations around 4-40 Hz) are used to drive the respiratory system, and the mechanical characteristic of the respiratory system can be determined with the linear system identification theory. Thus, respiratory mechanical properties and components at different frequency and location of the airway can be explored by specifically developed forcing waveforms. In this paper, the theory, methodology and clinical application of the FOT is reviewed, including measure ment theory, driving signals, models of respiratory system, algorithm for impedance identification, and requirement on apparatus. Finally, the future development of this technique is also discussed.

  1. Comment on ``Precision measurement of the Casimir-Lifshitz force in a fluid''

    CERN Document Server

    Geyer, B; Mohideen, U; Mostepanenko, V M

    2007-01-01

    Recently J.N. Munday and F. Capasso [Phys. Rev. A {\\bf 75}, 060102(R) (2007); arXiv:0705.3793] claimed that they have performed a precision measurement of the Casimir force between a sphere and a plate coated with Au, both immersed in ethanol. The measurement results were claimed to be consistent with the Lifshitz theory. We demonstrate that in this paper the Casimir force between the smooth surfaces of the test bodies was computed inaccurately with an error of up to 25%. We show also that the attractive electrostatic force only due to the surface potential differences was underestimated by a factor of 590 and the charge double layer interaction was not taken into account. All this leads to the conclusion that the results of this experiment are in fact uncertain.

  2. Minimising the effect of nanoparticle deformation in intermittent contact amplitude modulation atomic force microscopy measurements

    Science.gov (United States)

    Babic, Bakir; Lawn, Malcolm A.; Coleman, Victoria A.; Jämting, Åsa K.; Herrmann, Jan

    2016-06-01

    The results of systematic height measurements of polystyrene (PS) nanoparticles using intermittent contact amplitude modulation atomic force microscopy (IC-AM-AFM) are presented. The experimental findings demonstrate that PS nanoparticles deform during AFM imaging, as indicated by a reduction in the measured particle height. This deformation depends on the IC-AM-AFM imaging parameters, material composition, and dimensional properties of the nanoparticles. A model for nanoparticle deformation occurring during IC-AM-AFM imaging is developed as a function of the peak force which can be calculated for a particular set of experimental conditions. The undeformed nanoparticle height can be estimated from the model by extrapolation to zero peak force. A procedure is proposed to quantify and minimise nanoparticle deformation during IC-AM-AFM imaging, based on appropriate adjustments of the experimental control parameters.

  3. A bite in the playroom: Managing human bites in child care settings

    OpenAIRE

    2008-01-01

    Young children bite each other frequently in child care settings, but the bites rarely break the skin and the risk of infection is minimal. Nevertheless, parents and child care personnel may be concerned about infection, especially with blood-borne viruses. The present document reviews the literature concerning infections following bites in child care settings, and provides recommendations for prevention and management of such incidents.

  4. Development of a quartz tuning-fork-based force sensor for measurements in the tens of nanoNewton force range during nanomanipulation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Oiko, V. T. A., E-mail: oiko@ifi.unicamp.br; Rodrigues, V.; Ugarte, D. [Instituto de Física “Gleb Wataghin,” Univ. Estadual de Campinas (UNICAMP), Campinas 13083-859 (Brazil); Martins, B. V. C. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada); Silva, P. C. [Laboratório Nacional de Nanotecnologia, CNPEM, Campinas 13083-970 (Brazil)

    2014-03-15

    Understanding the mechanical properties of nanoscale systems requires new experimental and theoretical tools. In particular, force sensors compatible with nanomechanical testing experiments and with sensitivity in the nN range are required. Here, we report the development and testing of a tuning-fork-based force sensor for in situ nanomanipulation experiments inside a scanning electron microscope. The sensor uses a very simple design for the electronics and it allows the direct and quantitative force measurement in the 1–100 nN force range. The sensor response is initially calibrated against a nN range force standard, as, for example, a calibrated Atomic Force Microscopy cantilever; subsequently, applied force values can be directly derived using only the electric signals generated by the tuning fork. Using a homemade nanomanipulator, the quantitative force sensor has been used to analyze the mechanical deformation of multi-walled carbon nanotube bundles, where we analyzed forces in the 5–40 nN range, measured with an error bar of a few nN.

  5. First Pediatric Case of Tularemia after a Coyote Bite

    OpenAIRE

    Chomel, Bruno B.; Jane A. Morton; Kasten, Rickie W.; Chao-chin Chang

    2016-01-01

    Bite-transmitted tularemia is a rare event in humans and most of the cases have been associated with cat bites. We report the first pediatric case of tularemia caused by a coyote (Canis latrans) bite. Coyotes can be healthy carriers of Francisella tularensis and transmit this infectious agent through a bite. Pediatricians should be aware of this risk after a carnivore bite and implement appropriate antibiotic therapy, as amoxicillin/clavulanate potassium (Augmentin) may have prolonged the typ...

  6. Harmonic Force Spectroscopy measures load-dependent kinetics of individual human β-cardiac myosin molecules

    DEFF Research Database (Denmark)

    Sung, Jongmin; Nag, Suman; Mortensen, Kim;

    2015-01-01

    Molecular motors are responsible for numerous cellular processes from cargo transport to heart contraction. Their interactions with other cellular components are often transient and exhibit kinetics that depend on load. Here, we measure such interactions using ‘harmonic force spectroscopy...

  7. Ultrasonic Measurement of Strain Distribution Inside Object Cyclically Compressed by Dual Acoustic Radiation Force

    Science.gov (United States)

    Odagiri, Yoshitaka; Hasegawa, Hideyuki; Kanai, Hiroshi

    2008-05-01

    One possible way to evaluate acupuncture therapy quantitatively is to measure the change in the elastic property of muscle after application of the therapy. Many studies have been conducted to measure mechanical properties of tissues using ultrasound-induced acoustic radiation force. To assess mechanical properties, strain must be generated in an object. However, a single radiation force is not effective because it mainly generates translational motion when the object is much harder than the surrounding medium. In this study, two cyclic radiation forces are simultaneously applied to a muscle phantom from two opposite horizontal directions so that the object is cyclically compressed in the horizontal direction. By the horizontal compression, the object is expanded vertically based on its incompressibility. The resultant vertical displacement is measured using another ultrasound pulse. Two ultrasonic transducers for actuation were both driven by the sum of two continuous sinusoidal signals at two slightly different frequencies [1 MHz and (1 M + 5) Hz]. The displacement of several micrometers in amplitude, which fluctuated at 5 Hz, was measured by the ultrasonic phased tracking method. Increase in thickness inside the object was observed just when acoustic radiation forces increased. Such changes in thickness correspond to vertical expansion due to horizontal compression.

  8. New Constraints on the Yukawa-Type Hypothetical Interaction From The Recent Casimir Force Measurement

    CERN Document Server

    Bordag, M; Mostepanenko, V M

    1997-01-01

    We calculate the constraints on the constants of hypothetical long-range interactions which follow from the recent measurement of the Casimir force. A comparison with previous constraints is given. The new constraints are up to a factor of 3000 stronger in some parameter regions .

  9. Method and system for measuring gate valve clearances and seating force

    Science.gov (United States)

    Casada, Donald A.; Haynes, Howard D.; Moyers, John C.; Stewart, Brian K.

    1996-01-01

    Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner.

  10. Modeling the effect of probe force on length measurements on polymer parts

    DEFF Research Database (Denmark)

    Mohammadi, Ali; Sonne, Mads Rostgaard; Dalla Costa, Giuseppe;

    2016-01-01

    work, Hertzian contact theory was applied to find the deformation analytically, where the measuring force was imposed to the part. Material properties of the polymer and radius of the probe tip were known parameters. The finite element software ABAQUS was then used to model the contact problem...

  11. Determination of Oxygen Transport Properties from Flux and Driving Force Measurements

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas; Søgaard, Martin; Hendriksen, Peter Vang

    2007-01-01

    We demonstrate that an electrolyte probe can be used to measure the difference in oxygen chemical potential across the surface, when an oxygen flux is forced through an oxygen permeable membrane disk. The oxygen flux as well as the total oxygen chemical potential difference is carefully controlle...

  12. The knee adduction moment measured with an instrumented force shoe in patients with knee osteoarthritis

    NARCIS (Netherlands)

    Noort, van den Josien C.; Esch, van der Martin; Steultjens, Martijn P.M.; Dekker, Joost; Schepers, H. Martin; Veltink, Peter H.; Harlaar, Jaap

    2012-01-01

    The external knee adduction moment (KAdM) during gait is an important parameter in patients with knee osteoarthritis (OA). KAdM measurement is currently restricted to instruments only available in gait laboratories. However, ambulatory movement analysis technology, including instrumented force shoes

  13. THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY

    Science.gov (United States)

    THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY. William F. McDonnell Human Studies Division, NHEERL, U.S. Environmental Protection Agency, RTP, NC 27711. Short-term exposure to ozone results in a neurally-mediated decrease in the ab...

  14. Measurement of Levitation Forces of High-"T[subscript c] Superconductors

    Science.gov (United States)

    Becker, M.; Koblischka, M. R.; Hartmann, U.

    2010-01-01

    We show the construction of a so-called levitation balance which is capable of measuring the levitation forces between a permanent magnet and a superconducting high-T[subscript c] thin film sample. The underlying theoretical basis is discussed in detail. The experiment is performed as an introductory physics experiment for school students as well…

  15. Flexible Piezoelectric Tactile Sensor Array for Dynamic Three-Axis Force Measurement

    Science.gov (United States)

    Yu, Ping; Liu, Weiting; Gu, Chunxin; Cheng, Xiaoying; Fu, Xin

    2016-01-01

    A new flexible piezoelectric tactile sensor array based on polyvinylidene fluoride (PVDF) film is proposed for measuring three-axis dynamic contact force distribution. The array consists of six tactile units arranged as a 3 × 2 matrix with spacing 8 mm between neighbor units. In each unit, a PVDF film is sandwiched between four square-shaped upper electrodes and one square-shaped lower electrode, forming four piezoelectric capacitors. A truncated pyramid bump is located above the four piezoelectric capacitors to improve force transmission. A three-axis contact force transmitted from the top of the bump will lead to the four piezoelectric capacitors underneath undergoing different charge changes, from which the normal and shear components of the force can be calculated. A series of dynamic tests have been carried out by exerting sinusoidal forces with amplitudes ranging from 0 to 0.5 N in the x-axis, 0 to 0.5 N in the y-axis, and 0 to 1.5 N in the z-axis, separately. The tactile units show good sensitivities with 14.93, 14.92, and 6.62 pC/N in the x-, y-, and z-axes, respectively. They can work with good linearity, relatively low coupling effect, high repeatability, and acceptable frequency response in the range of 5–400 Hz to both normal and shear load. In addition, dynamic three-axis force measurement has been conducted for all of the tactile units. The average errors between the applied and calculated forces are 10.68% ± 6.84%. Furthermore, the sensor array can be easily integrated onto a curved surface, such as robotic and prosthetic hands, due to its excellent flexibility. PMID:27271631

  16. Impact-force sparse reconstruction from highly incomplete and inaccurate measurements

    Science.gov (United States)

    Qiao, Baijie; Zhang, Xingwu; Gao, Jiawei; Chen, Xuefeng

    2016-08-01

    The classical l2-norm-based regularization methods applied for force reconstruction inverse problem require that the number of measurements should not be less than the number of unknown sources. Taking into account the sparse nature of impact-force in time domain, we develop a general sparse methodology based on minimizing l1-norm for solving the highly underdetermined model of impact-force reconstruction. A monotonic two-step iterative shrinkage/thresholding (MTWIST) algorithm is proposed to find the sparse solution to such an underdetermined model from highly incomplete and inaccurate measurements, which can be problematic with Tikhonov regularization. MTWIST is highly efficient for large-scale ill-posed problems since it mainly involves matrix-vector multiplies without matrix factorization. In sparsity frame, the proposed sparse regularization method can not only determine the actual impact location from many candidate sources but also simultaneously reconstruct the time history of impact-force. Simulation and experiment including single-source and two-source impact-force reconstruction are conducted on a simply supported rectangular plate and a shell structure to illustrate the effectiveness and applicability of MTWIST, respectively. Both the locations and force time histories of the single-source and two-source cases are accurately reconstructed from a single accelerometer, where the high noise level is considered in simulation and the primary noise in experiment is supposed to be colored noise. Meanwhile, the consecutive impact-forces reconstruction in a large-scale (greater than 104) sparse frame illustrates that MTWIST has advantages of computational efficiency and identification accuracy over Tikhonov regularization.

  17. Trial manufacture of rotary friction tester and frictional force measurement of metals

    CERN Document Server

    Abe, T; Kanari, M; Tanzawa, S

    2002-01-01

    In the plasma confinement type fusion reactor, in-vessel structures such as a blanket module slide at the joints each other when plasma disruption occurs, and then frictional heat is generated there. Therefore, for the selection of material and the use as the design data, it is important to understand the frictional characteristics of metals and ceramic films in the vacuum. In the present study, we have manufactured a prototype of rotary friction tester and examined the performances of the tester. The frictional characteristics of metals in the room air was measured using the friction tester, and the results obtained are as follows. A drifting friction force for a constant time and a friction force during the idling were 98 mN and 225 mN, respectively. These values were sufficiently small as compared to pressing load (9.8 - 57.8 N) used in the friction test. In a friction force measurement of stainless steel, dynamic friction force obeyed Amontons' law which indicated that dynamic friction force is not depend...

  18. Design and Analysis of a Sensor System for Cutting Force Measurement in Machining Processes.

    Science.gov (United States)

    Liang, Qiaokang; Zhang, Dan; Coppola, Gianmarc; Mao, Jianxu; Sun, Wei; Wang, Yaonan; Ge, Yunjian

    2016-01-07

    Multi-component force sensors have infiltrated a wide variety of automation products since the 1970s. However, one seldom finds full-component sensor systems available in the market for cutting force measurement in machine processes. In this paper, a new six-component sensor system with a compact monolithic elastic element (EE) is designed and developed to detect the tangential cutting forces Fx, Fy and Fz (i.e., forces along x-, y-, and z-axis) as well as the cutting moments Mx, My and Mz (i.e., moments about x-, y-, and z-axis) simultaneously. Optimal structural parameters of the EE are carefully designed via simulation-driven optimization. Moreover, a prototype sensor system is fabricated, which is applied to a 5-axis parallel kinematic machining center. Calibration experimental results demonstrate that the system is capable of measuring cutting forces and moments with good linearity while minimizing coupling error. Both the Finite Element Analysis (FEA) and calibration experimental studies validate the high performance of the proposed sensor system that is expected to be adopted into machining processes.

  19. Design and Analysis of a Sensor System for Cutting Force Measurement in Machining Processes

    Directory of Open Access Journals (Sweden)

    Qiaokang Liang

    2016-01-01

    Full Text Available Multi-component force sensors have infiltrated a wide variety of automation products since the 1970s. However, one seldom finds full-component sensor systems available in the market for cutting force measurement in machine processes. In this paper, a new six-component sensor system with a compact monolithic elastic element (EE is designed and developed to detect the tangential cutting forces Fx, Fy and Fz (i.e., forces along x-, y-, and z-axis as well as the cutting moments Mx, My and Mz (i.e., moments about x-, y-, and z-axis simultaneously. Optimal structural parameters of the EE are carefully designed via simulation-driven optimization. Moreover, a prototype sensor system is fabricated, which is applied to a 5-axis parallel kinematic machining center. Calibration experimental results demonstrate that the system is capable of measuring cutting forces and moments with good linearity while minimizing coupling error. Both the Finite Element Analysis (FEA and calibration experimental studies validate the high performance of the proposed sensor system that is expected to be adopted into machining processes.

  20. Design and Analysis of a Sensor System for Cutting Force Measurement in Machining Processes.

    Science.gov (United States)

    Liang, Qiaokang; Zhang, Dan; Coppola, Gianmarc; Mao, Jianxu; Sun, Wei; Wang, Yaonan; Ge, Yunjian

    2016-01-01

    Multi-component force sensors have infiltrated a wide variety of automation products since the 1970s. However, one seldom finds full-component sensor systems available in the market for cutting force measurement in machine processes. In this paper, a new six-component sensor system with a compact monolithic elastic element (EE) is designed and developed to detect the tangential cutting forces Fx, Fy and Fz (i.e., forces along x-, y-, and z-axis) as well as the cutting moments Mx, My and Mz (i.e., moments about x-, y-, and z-axis) simultaneously. Optimal structural parameters of the EE are carefully designed via simulation-driven optimization. Moreover, a prototype sensor system is fabricated, which is applied to a 5-axis parallel kinematic machining center. Calibration experimental results demonstrate that the system is capable of measuring cutting forces and moments with good linearity while minimizing coupling error. Both the Finite Element Analysis (FEA) and calibration experimental studies validate the high performance of the proposed sensor system that is expected to be adopted into machining processes. PMID:26751451

  1. Interactions between Rotavirus and Suwannee River Organic Matter: Aggregation, Deposition, and Adhesion Force Measurement

    KAUST Repository

    Gutierrez, Leonardo

    2012-08-21

    Interactions between rotavirus and Suwannee River natural organic matter (NOM) were studied by time-resolved dynamic light scattering, quartz crystal microbalance, and atomic force microscopy. In NOM-containing NaCl solutions of up to 600 mM, rotavirus suspension remained stable for over 4 h. Atomic force microscopy (AFM) measurement for interaction force decay length at different ionic strengths showed that nonelectrostatic repulsive forces were mainly responsible for eliminating aggregation in NaCl solutions. Aggregation rates of rotavirus in solutions containing 20 mg C/L increased with divalent cation concentration until reaching a critical coagulation concentration of 30 mM CaCl2 or 70 mM MgCl2. Deposition kinetics of rotavirus on NOM-coated silica surface was studied using quartz crystal microbalance. Experimental attachment efficiencies for rotavirus adsorption to NOM-coated surface in MgCl2 solution were lower than in CaCl2 solution at a given divalent cation concentration. Stronger adhesion force was measured for virus-virus and virus-NOM interactions in CaCl2 solution compared to those in MgCl2 or NaCl solutions at the same ionic strength. This study suggested that divalent cation complexation with carboxylate groups in NOM and on virus surface was an important mechanism in the deposition and aggregation kinetics of rotavirus. © 2012 American Chemical Society.

  2. Analyzing excitation forces acting on a plate based on measured acoustic pressure.

    Science.gov (United States)

    Wu, Sean F; Zhou, Pan

    2016-07-01

    This paper presents a theoretical study on "seeing" through an elastic structure to uncover the root cause of sound and vibration by using nearfield acoustical holography (NAH) and normal modes expansion. This approach is of generality because vibro-acoustic responses on the surface of a vibrating structure can always be reconstructed, exactly or approximately. With these vibro-acoustic responses, excitation forces acting on the structure can always be determined, analytically or numerically, given any set of boundary conditions. As an example, the explicit formulations for reconstructing time-harmonic excitation forces, including point, line and surface forces, and their arbitrary combinations acting on a rectangular thin plate in vacuum mounted on an infinite baffle are presented. The reason for choosing this example is that the analytic solutions to vibro-acoustic responses are available, and in-depth analyses of results are possible. Results demonstrate that this approach allows one to identify excitation forces based on measured acoustic pressures and reveal their characteristics such as locations, types and amplitudes, as if one could "see" excitation forces acting behind the plate based on acoustic pressure measured on the opposite side. This approach is extendable to general elastic structures, except that in such circumstance numerical results must be sought. PMID:27475174

  3. [Bites of venomous snakes in Switzerland].

    Science.gov (United States)

    Plate, Andreas; Kupferschmidt, Hugo; Schneemann, Markus

    2016-06-01

    Although snake bites are rare in Europe, there are a constant number of snake bites in Switzerland. There are two domestic venomous snakes in Switzerland: the aspic viper (Vipera aspis) and the common European adder (Vipera berus). Bites from venomous snakes are caused either by one of the two domestic venomous snakes or by an exotic venomous snake kept in a terrarium. Snake- bites can cause both a local and/or a systemic envenoming. Potentially fatal systemic complications are related to disturbances of the hemostatic- and cardiovascular system as well as the central or peripheral nervous system. Beside a symptomatic therapy the administration of antivenom is the only causal therapy to neutralize the venomous toxins.

  4. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... information Housing & travel Education FAQs Mobile app Exhibit hall 2017 Annual Meeting Derm Exam Prep Course Essentials ... and can continue through adulthood, and the side effects can be more than cosmetic. Repeated nail biting ...

  5. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... like biting your nails, try playing with a stress ball or silly putty instead. This will help ... of hangnails, or other triggers, such as boredom, stress, or anxiety. By figuring out what causes you ...

  6. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... Common coding issues ICD-10 Audits, fraud, and abuse Test your knowledge Derm Coding Consult AAD coding ... Injured skin Nail care Artificial nails Healthy nails Child nail care Manicure safety Nail biting Younger skin ...

  7. Rat Bite Fever Resembling Rheumatoid Arthritis

    Directory of Open Access Journals (Sweden)

    Ripa Akter

    2016-01-01

    Full Text Available Rat bite fever is rare in Western countries. It can be very difficult to diagnose as blood cultures are typically negative and a history of rodent exposure is often missed. Unless a high index of suspicion is maintained, the associated polyarthritis can be mistaken for rheumatoid arthritis. We report a case of culture-positive rat bite fever in a 46-year-old female presenting with fever and polyarthritis. The clinical presentation mimicked rheumatoid arthritis. Infection was complicated by discitis, a rare manifestation. We discuss the diagnosis and management of this rare zoonotic infection. We also review nine reported cases of rat bite fever, all of which had an initial presumptive diagnosis of a rheumatological disorder. Rat bite fever is a potentially curable infection but can have a lethal course if left untreated.

  8. Beware of Bug Bites and Stings

    Science.gov (United States)

    ... relief. Oral OTC drugs, such as ibuprofen and acetaminophen, can provide relief of pain from bites and ... sneezing, wheezing, hives, nausea, vomiting, diarrhea, sudden anxiety, dizziness, difficulty breathing, chest tightness, and itching or swelling ...

  9. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... Structure Program SPOTme® Skin Cancer Screening Program Volunteer Recognition Program AAD and AADA Historian Leadership Institute Programs ... your fingers and from your nails to your face and mouth. To help you stop biting your ...

  10. Philodryas patagoniensis bite and local envenoming.

    Science.gov (United States)

    Nishioka, S A; Silveira, P V

    1994-01-01

    A 5-year-old boy bitten by a specimen of Philodryas patagoniensis, a colubrid snake currently classified as nonvenomous, developed signs of local envenoming characterized by swelling and warmth on the bitten limb. This is the first time that local envenoming following Philodryas patagoniensis bite is recognized. Based on the clinical findings and misidentification of the snake, the patient was treated as a victim of Bothrops bite, having received unnecessarily the specific antivenom. Educational efforts to make doctors and health workers capable to identify correctly venomous snakes are necessary, to avoid inappropriate indication of antivenom and decrease the risk of its potentially harmful untoward effects. Examination of the bite site can be useful to the differential diagnosis between pit viper and colubrid bites. PMID:7855493

  11. [Bites of venomous snakes in Switzerland].

    Science.gov (United States)

    Plate, Andreas; Kupferschmidt, Hugo; Schneemann, Markus

    2016-06-01

    Although snake bites are rare in Europe, there are a constant number of snake bites in Switzerland. There are two domestic venomous snakes in Switzerland: the aspic viper (Vipera aspis) and the common European adder (Vipera berus). Bites from venomous snakes are caused either by one of the two domestic venomous snakes or by an exotic venomous snake kept in a terrarium. Snake- bites can cause both a local and/or a systemic envenoming. Potentially fatal systemic complications are related to disturbances of the hemostatic- and cardiovascular system as well as the central or peripheral nervous system. Beside a symptomatic therapy the administration of antivenom is the only causal therapy to neutralize the venomous toxins. PMID:27269771

  12. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... hair, and nail care Nail care Nail biting public SPOT Skin Cancer™ Diseases and treatments Skin, hair, ... Member resources Practice Tools Education Meetings & events Advocacy Public & patients AAD Resources For: Dermatologists in the US ...

  13. How to Stop Biting Your Nails

    Medline Plus

    Full Text Available ... Common coding issues ICD-10 Audits, fraud, and abuse Test your knowledge Derm Coding Consult AAD coding ... from biting their nails. Get regular manicures: Spending money to keep your nails looking attractive may make ...

  14. Animal Bites - Multiple Languages: MedlinePlus

    Science.gov (United States)

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Animal Bites URL of this page: https://medlineplus.gov/languages/animalbites.html Other topics A-Z A B ...

  15. Rat Bite Fever Resembling Rheumatoid Arthritis.

    Science.gov (United States)

    Akter, Ripa; Boland, Paul; Daley, Peter; Rahman, Proton; Al Ghanim, Nayef

    2016-01-01

    Rat bite fever is rare in Western countries. It can be very difficult to diagnose as blood cultures are typically negative and a history of rodent exposure is often missed. Unless a high index of suspicion is maintained, the associated polyarthritis can be mistaken for rheumatoid arthritis. We report a case of culture-positive rat bite fever in a 46-year-old female presenting with fever and polyarthritis. The clinical presentation mimicked rheumatoid arthritis. Infection was complicated by discitis, a rare manifestation. We discuss the diagnosis and management of this rare zoonotic infection. We also review nine reported cases of rat bite fever, all of which had an initial presumptive diagnosis of a rheumatological disorder. Rat bite fever is a potentially curable infection but can have a lethal course if left untreated. PMID:27366177

  16. Tarantula bite leads to death and gangrene

    Directory of Open Access Journals (Sweden)

    Banerjee Kalyan

    1997-01-01

    Full Text Available Chilobrachys hardwikii-giant black hairy spider bite produced two deaths, one case of gangrene of the foot and urticarial rashes in another person in a remote village of Churulia 30 km from Asansol.

  17. A method of comparison between a force curve measured on a solvated surface and the solvation structure

    CERN Document Server

    Amano, Ken-ichi

    2012-01-01

    Recent surface force apparatus (SFA) and atomic force microscopy (AFM) can measure force curves between a probe and a sample surface in solvent. The force curve is thought as the solvation structure in some articles, because its shape is generally oscilltive and pitch of the oscillation is about the same as diameter of the solvent. However, it is not the solvation structure. It is just only a mean force between the probe and the sample surface. Therefore, a relation between the mean force and the solvation structure must be elucidated theoretically to deepen understanding of the measured result (the mean force). In this letter, we briefly explain the relation and a method for comparing the measured mean force and the solvation structure (obtained by a simulation or a liquid theory) by using basic statistical mechanics of liquid.

  18. Sub-Kelvin Cooling of a Macroscopic Oscillator and femto-Newton Force Measurement

    OpenAIRE

    Mueller, F.; Heugel, S.; Wang, L. J.

    2007-01-01

    Measuring very small forces, particularly those of a gravitational nature, has always been of great interest, as fundamental tests of our understanding of the physical laws. Ultra-long period mechanical oscillators, typically used in such measurements, will have kT/2 of thermal energy associated with each degree of freedom, owing to the equal-partition of energy. Moreover, additional seismic fluctuations in the low frequency band can raise this equivalent temperature significantly to 10^5 K. ...

  19. Measurement of external forces and torques on a large pointing system

    Science.gov (United States)

    Morenus, R. C.

    1980-01-01

    Methods of measuring external forces and torques are discussed, in general and as applied to the Large Pointing System wind tunnel tests. The LPS tests were in two phases. The first test was a preliminary test of three models representing coelostat, heliostat, and on-gimbal telescope configurations. The second test explored the coelostat configuration in more detail. The second test used a different setup for measuring external loads. Some results are given from both tests.

  20. Modified Thurow appliance: a clinical alternative for correcting skeletal open bite.

    Science.gov (United States)

    Stuani, Maria Bernadete Sasso; Stuani, Andréa Sasso; Stuani, Adriana Sasso

    2005-07-01

    Open bite malocclusion is frequently discussed in orthodontics; diagnosis, treatment, and retention can be difficult because this malocclusion has numerous correlated etiological factors. The earlier this malocclusion is corrected, the better the prognosis will be, especially when the problem is skeletal. This article presents a patient with skeletal open bite who was treated in the mixed dentition with an orthodontic appliance that included an acrylic occlusal splint and an expansion screw, based on the original Thurow appliance, to guide the vertical force against the posterior teeth and the alveolar process.

  1. Etiological aspects of anterior open bite

    Directory of Open Access Journals (Sweden)

    Stojanović Ljiljana

    2007-01-01

    Full Text Available Introduction. Open bite is a multifactorial phenomenon and no single factor can account for open-bite. Etiology plays an important role in diagnosis. Heredity, unfavorable growth patterns, incorrect jaw postoure, are the characteristics of skeletal open bite. Digit sucking. Depending on where the thumb is placed, a number of different types of dental problems can develop. Malocclusions of the late mixed or permanent dentitions, caused by thumb sucking are not self corrected and orthodontic treatment is necessary for their correction. Lymphatic tissue. In order to produce oral respiration, the mandible is postured inferiorly with the tongue protruded and resting against the oral floor. This postural alteration induces dental and skeletal modifications similar to those caused by thumb sucking. This may cause excessive eruption of the posterior teeth, leading to an increase in the vertical dimension of the face and result in development of anterior open bite. Tongue thrust. Tongue habits cause an anterior open bite or they develop secondarily to thumb sucking. In skeletal open bite the tongue habit acts as a secondary factor which helps to maintain or exacerbate the condition. Many orthodontists have had a discouraging experience of completing dental treatment, with what appeared to be good results, only to discover that the case had relapsed because the patient had a tongue thrust swallowing pattern. Conclusion. Dentoalveolar or habitual open bite is caused by habits, which influence the growth and development of dentoalveolar processes and contribute to occlusal disharmonies. Prior to eruption of adult dentition, open bite related to oral habits is usually not a concern as when the habits stop, because the erupting dentition tends to improve spontaneously. Treatment is usually not necessary until permanent teeth erupt (~6 years old. .

  2. Force measurements in positive unipolar wire-to-plane corona discharges in air

    CERN Document Server

    de Haan, V O

    2004-01-01

    Measurements of force generated by a positive unipolar wire-to-plane corona discharge in air are compared with numerical simulations. The generated force does not depend on the ion or electron mobilities, preventing the influence of uncertainty and variation of these parameters. A method is described to simulate the voltage and charge distribution for a wire-to-plane set-up. This method enables the determination of the transition between unipolar and bipolar discharges. In the experimental set-up breakdown electric field of air reduces with increasing discharge current.

  3. Polymer-based flexible capacitive sensor for three-axial force measurements

    Science.gov (United States)

    Dobrzynska, J. A.; Gijs, M. A. M.

    2013-01-01

    We have developed a flexible-substrate-based three-axial force sensor, composed of finger-shaped electrode capacitors, whose operation is based on the measurement of a capacitance change induced upon applying a three-axial load. The electrode design supports high sensitivity to shear forces. An overall flexibility of the sensor and elasticity of the capacitor's dielectric is obtained by integrating three polymers in the sensor's technology process, namely polyimide, parylene-C, and polydimethylsiloxane, combined with standard metallization processes. We have theoretically modeled the sensor's capacitance and its three-axial force sensitivity. The unit capacitors have static capacitances in the range of 20 pF. The electro-mechanical characterization of the capacitors reveals in the normal direction a sensitivity Sz = 0.024 kPa-1 for pressures <10 kPa, whereas for higher pressures the measured sensitivity Sz = 6.6 × 10-4 kPa-1. Typical measured shear force sensitivity Sx = 2.8 × 10-4 kPa-1. These values give our transducer high potential for use in skin-like sensing applications.

  4. Sub-Kelvin Cooling of a Macroscopic Oscillator and femto-Newton Force Measurement

    CERN Document Server

    Müller, F; Wang, L J

    2007-01-01

    Measuring very small forces, particularly those of a gravitational nature, has always been of great interest, as fundamental tests of our understanding of the physical laws. Ultra-long period mechanical oscillators, typically used in such measurements, will have kT/2 of thermal energy associated with each degree of freedom, owing to the equal-partition of energy. Moreover, additional seismic fluctuations in the low frequency band can raise this equivalent temperature significantly to 10^5 K. Recently, various methods using opto-mechanical forces have been reported to decrease this thermal energy for MHz, micro-cantilever oscillators, effectively cooling them. Here we show the direct, dynamical cooling of a gram-size, macroscopic oscillator to 300 mK in equivalent temperature - noise reduction by a factor of 10^6. By precisely measuring the torsional oscillator's position, we dynamically provide an external 'viscous' damping force. Such an added, dissipative force is essentially free of noise, resulting in rap...

  5. Polymer-based flexible capacitive sensor for three-axial force measurements

    International Nuclear Information System (INIS)

    We have developed a flexible-substrate-based three-axial force sensor, composed of finger-shaped electrode capacitors, whose operation is based on the measurement of a capacitance change induced upon applying a three-axial load. The electrode design supports high sensitivity to shear forces. An overall flexibility of the sensor and elasticity of the capacitor's dielectric is obtained by integrating three polymers in the sensor's technology process, namely polyimide, parylene-C, and polydimethylsiloxane, combined with standard metallization processes. We have theoretically modeled the sensor's capacitance and its three-axial force sensitivity. The unit capacitors have static capacitances in the range of 20 pF. The electro-mechanical characterization of the capacitors reveals in the normal direction a sensitivity Sz = 0.024 kPa−1 for pressures <10 kPa, whereas for higher pressures the measured sensitivity Sz = 6.6 × 10−4 kPa−1. Typical measured shear force sensitivity Sx = 2.8 × 10−4 kPa−1. These values give our transducer high potential for use in skin-like sensing applications. (paper)

  6. Partnership for the Revitalization of National Wind Tunnel Force Measurement Capability

    Science.gov (United States)

    Rhew, Ray D.; Skelley, Marcus L.; Woike, Mark R.; Bader, Jon B.; Marshall, Timothy J.

    2009-01-01

    Lack of funding and lack of focus on research over the past several years, coupled with force measurement capabilities being decentralized and distributed across the National Aeronautics and Space Administration (NASA) research centers, has resulted in a significant erosion of (1) capability and infrastructure to produce and calibrate force measurement systems; (2) NASA s working knowledge of those systems; and (3) the quantity of high-quality, full-capability force measurement systems available for use in aeronautics testing. Simultaneously, and at proportional rates, the capability of industry to design, manufacture, and calibrate these test instruments has been eroding primarily because of a lack of investment by the aeronautics community. Technical expertise in this technology area is a core competency in aeronautics testing; it is highly specialized and experience-based, and it represents a niche market for only a few small precision instrument shops in the United States. With this backdrop, NASA s Aeronautics Test Program (ATP) chartered a team to examine the issues and risks associated with the problem, focusing specifically on strain- gage balances. The team partnered with the U.S. Air Force s Arnold Engineering Development Center (AEDC) to exploit their combined capabilities and take a national level government view of the problem. This paper describes the team s approach, its findings, and its recommendations, and the current status for revitalizing the government s balance capability with respect to designing, fabricating, calibrating, and using the instruments.

  7. Jejunal morphology and blood metabolites in tail biting, victim and control pigs.

    Science.gov (United States)

    Palander, P A; Heinonen, M; Simpura, I; Edwards, S A; Valros, A E

    2013-09-01

    Tail biting has several identified feeding-related risk factors. Tail biters are often said to be lighter and thinner than other pigs in the pen, possibly because of nutrition-related problems such as reduced feed intake or inability to use nutrients efficiently. This can lead to an increase in foraging behavior and tail biting. In this study, a total of 55 pigs of different ages were selected according to their tail-biting behavior (bouts/hour) and pen-feeding system to form eight experimental groups: tail-biting pigs (TB), victim pigs (V) and control pigs from a tail-biting pen (Ctb) and control pen (Cno) having either free access to feed with limited feeding space or meal feeding from a long trough. After euthanasia, a segment of jejunal cell wall was cut from 50 cm (S50) and 100 cm (S100) posterior to the bile duct. Villus height, crypt depth and villus : crypt ratio (V : C) were measured morphometrically. Blood serum concentration of minerals and plasma concentration of amino acids (AA) was determined. Villus height was greater in Cno than Ctb pigs in the proximal and mid-jejunum (P pigs, and that of Pi in V compared with all the other pigs. Many non-essential AA were lower in pigs from tail-biting pens, and particularly in victim pigs. Free access feeding with shared feeding space was associated with lower levels of essential AA in blood than meal feeding with simultaneous feeding space. Our data suggest that being a pig in a tail-biting pen is associated with decreased jejunal villus height and blood AA levels, possibly because of depressed absorption capacity, feeding behavior or environmental stress associated with tail biting. Victim pigs had lower concentrations of AA and Pi in plasma, possibly as a consequence of being bitten. PMID:23597306

  8. Endemic mansonellosis in Emohua Local Government Area, Nigeria: human parasitaemia and Culicoides biting patterns

    Directory of Open Access Journals (Sweden)

    E.C. Uttah, S. Etim, C. Okonofua & O.E. Effiom

    2011-03-01

    Full Text Available Background & objectives: The study was aimed at elucidating the prevalence and intensity of Mansonellaperstans microfilaraemia in the Emohua Local Government Area, Nigeria, and ascertaining the abundance,circadian, and the annual biting patterns of the Culicoides vector.Methods: Thick smear of 50 μl finger-prick blood stained with Giemsa was examined microscopically in across-sectional study. Vector landing collection on human bait was employed in a longitudinal study of thevector biting patterns, carried out between July 2005 and August 2006.Results: Of 1486 individuals examined, 11.2% of both males and females were positive for M. perstansmicrofilaraemia. Microfilaraemia appeared early in life. The overall geometric mean intensity among those withpositive microfilaraemia was 117 mf/ml (121 mf/ml for males and 113 mf/ml for females. The differences ingeometric mean intensity between different age groups were statistically significant (one-way analysis of variance;p <0.05, being highest in the oldest age group (266 mf/ml. A total of 1183 female Culicoides sp were caughtfrom September 2005 to August 2006. The abundance of Culicoides sp was seasonal. The circadian bitingactivity had a broad peak between 0700 and 1200 hrs. The monthly biting rates ranged from zero bite per personper month in January 2006 to 1151 bites per person per month in June 2006. The annual biting rate was 7382bites per person per year.Conclusion: Majority of those with positive microfilaraemia were poor socioeconomically, underscoring theneed for health education and application of effective control measures against Culicoides biting midges inEmohua.

  9. Force measurements of TCR/pMHC recognition at T cell surface.

    Directory of Open Access Journals (Sweden)

    Pierre-Henri Puech

    Full Text Available The rupture forces and adhesion frequencies of single recognition complexes between an affinity selected peptide/MHC complex and a TCR at a murine hybridoma surface were measured using Atomic Force Microscopy. When the CD8 coreceptor is absent, the adhesion frequency depends on the nature of the peptide but the rupture force does not. When CD8 is present, no effect of the nature of the peptide is observed. CD8 is proposed to act as a time and distance lock, enabling the shorter TCR molecule to bridge the pMHC and have time to finely read the peptide. Ultimately, such experiments could help the dissection of the sequential steps by which the TCR reads the peptide/MHC complex in order to control T cell activation.

  10. Dynamic force measurement of rearrangements in a 2D network of droplets

    Science.gov (United States)

    Barkley, Solomon; Backholm, Matilda; Dalnoki-Veress, Kari

    2015-03-01

    The interaction between two liquid droplets in an immiscible liquid is well understood. However, the emulsions relevant to biological and industrial processes involve high concentrations of these droplets, and multi-body effects cannot be ignored. As droplets rearrange in response to a disturbance, the importance of individual pair-wise interactions between droplets changes with the geometry of neighbours. Here we report on an experimental setup consisting of a two- dimensional network of monodisperse droplets stabilized with a surfactant. The system is studied with micropipette deflection, which permits direct measurement of forces along with simultaneous imaging of the droplet network. One micropipette is used to apply a tensile or compressive force to the droplet cluster, while a second pipette acts as a force-transducing cantilever, deflecting in response to rearrangements of the droplets.

  11. A scheme for solving the plane-plane challenge in force measurements at the nanoscale.

    Science.gov (United States)

    Siria, Alessandro; Huant, Serge; Auvert, Geoffroy; Comin, Fabio; Chevrier, Joel

    2010-05-19

    Non-contact interaction between two parallel flat surfaces is a central paradigm in sciences. This situation is the starting point for a wealth of different models: the capacitor description in electrostatics, hydrodynamic flow, thermal exchange, the Casimir force, direct contact study, third body confinement such as liquids or films of soft condensed matter. The control of parallelism is so demanding that no versatile single force machine in this geometry has been proposed so far. Using a combination of nanopositioning based on inertial motors, of microcrystal shaping with a focused-ion beam (FIB) and of accurate in situ and real-time control of surface parallelism with X-ray diffraction, we propose here a "gedanken" surface-force machine that should enable one to measure interactions between movable surfaces separated by gaps in the micrometer and nanometer ranges.

  12. Force measurement and design of a torquing high-pull headgear.

    Science.gov (United States)

    Tabash, J W; Sandrik, J L; Bowman, D; Lang, R L; Klapper, L

    1984-07-01

    The dynamic extraoral force analyzer (DEFA) was found to be capable of measuring linear deflection as a function of force created by a headgear. Ten standard nontorqued face-bows with a cervical and a high-pull direction were tested to determine the reliability of the DEFA. Statistical analysis showed the DEFA to be reliable and accurate in differentiating various directions and deflections of maxillary molars. Doubled-over distal ends of the inner bow with 0 degree of torque and a parietal direction of pull were used as controls. The same face-bows with 9 degrees of buccal root torque were tested on the DEFA. These face-bows were tested to determine whether transverse translation without buccal crown tipping of the maxillary first molar will occur. Statistical analysis showed that transverse translation occurred at a force of 200 to 347 gm.

  13. A Scheme for Solving the Plane–Plane Challenge in Force Measurements at the Nanoscale

    Directory of Open Access Journals (Sweden)

    Comin Fabio

    2010-01-01

    Full Text Available Abstract Non-contact interaction between two parallel flat surfaces is a central paradigm in sciences. This situation is the starting point for a wealth of different models: the capacitor description in electrostatics, hydrodynamic flow, thermal exchange, the Casimir force, direct contact study, third body confinement such as liquids or films of soft condensed matter. The control of parallelism is so demanding that no versatile single force machine in this geometry has been proposed so far. Using a combination of nanopositioning based on inertial motors, of microcrystal shaping with a focused-ion beam (FIB and of accurate in situ and real-time control of surface parallelism with X-ray diffraction, we propose here a “gedanken” surface-force machine that should enable one to measure interactions between movable surfaces separated by gaps in the micrometer and nanometer ranges.

  14. Measurement of force sense reproduction in the knee joint: application of a new dynamometric device

    Science.gov (United States)

    Zavieh,, Minoo Khalkhali; Amirshakeri,, Bahram; Rezasoltani,, Asghar; Talebi,, Ghadam Ali; Kalantari,, Khosro Khademi; Nedaey,, Vahab; Baghban,, Alireza Akbarzadeh

    2016-01-01

    [Purpose] The aim of this study was to determine the reliability of a newly designed dynamometric device for use in frequent force producing/reproducing tasks on the knee joint. [Subjects and Methods] In this cross-sectional study (Development & Reliability), 30 young healthy males and females (age 23.4 ± 2.48 years) were selected among students of Tabriz University of Medical Sciences by simple randomized selection. The study instrument was designed to measure any isometric contraction force exerted by the knee joint flexor/extensor muscles, known as the ipsilateral and contralateral methods. Participant knees were fixed in 60° flexion, and each participant completed the entire set of measurements twice, 72 hours apart. [Results] The findings showed a good intraclass correlation coefficient of 0.73 to 0.81 for all muscle groups. The standard error of measurement and smallest detectable difference for flexor muscle groups were 0.37 and 1.02, respectively, while the values increased to standard error of measurement=0.38 and smallest detectable difference=1.05 for extensor muscle groups. [Conclusion] The device designed could quantify the forces producing/reproducing tasks on the knee joint with a high rate of reliability, and can probably be applied for outcome measurements in proprioceptive assessment of the knee joint.

  15. Testing the retention of attachments for implant overdentures - validation of an original force measurement system.

    Science.gov (United States)

    Fromentin, O; Lassauzay, C; Abi Nader, S; Feine, J; de Albuquerque Junior, R F

    2010-01-01

    The aim of this study was to validate an original portable device to measure attachment retention of implant overdentures both in the lab and in clinical settings. The device was built with a digital force measurement gauge (Imada) secured to a vertical wheel stand associated with a customized support to hold and position the denture in adjustable angulations. Sixteen matrix and patrix cylindrical stud attachments (Locator) were randomly assigned as in vitro test specimens. Attachment abutments were secured in an implant analogue hung to the digital force gauge or to the load cell of a traction machine used as the gold standard (Instron Universal Testing Machine). Matrices were secured in a denture duplicate attached to the customized support, permitting reproducibility of their position on both pulling devices. Attachment retention in the axial direction was evaluated by measuring maximum dislodging force or peak load during five consecutive linear dislodgments of each attachment on both devices. After a wear simulation, retention was measured again at several time periods. The peak load measurements with the customized Imada device were similar to those obtained with the gold standard Instron machine. These findings suggest that the proposed portable device can provide accurate information on the retentive properties of attachment systems for removable dental prostheses. PMID:19912482

  16. Testing the retention of attachments for implant overdentures - validation of an original force measurement system.

    Science.gov (United States)

    Fromentin, O; Lassauzay, C; Abi Nader, S; Feine, J; de Albuquerque Junior, R F

    2010-01-01

    The aim of this study was to validate an original portable device to measure attachment retention of implant overdentures both in the lab and in clinical settings. The device was built with a digital force measurement gauge (Imada) secured to a vertical wheel stand associated with a customized support to hold and position the denture in adjustable angulations. Sixteen matrix and patrix cylindrical stud attachments (Locator) were randomly assigned as in vitro test specimens. Attachment abutments were secured in an implant analogue hung to the digital force gauge or to the load cell of a traction machine used as the gold standard (Instron Universal Testing Machine). Matrices were secured in a denture duplicate attached to the customized support, permitting reproducibility of their position on both pulling devices. Attachment retention in the axial direction was evaluated by measuring maximum dislodging force or peak load during five consecutive linear dislodgments of each attachment on both devices. After a wear simulation, retention was measured again at several time periods. The peak load measurements with the customized Imada device were similar to those obtained with the gold standard Instron machine. These findings suggest that the proposed portable device can provide accurate information on the retentive properties of attachment systems for removable dental prostheses.

  17. Mechanics of biting in great white and sandtiger sharks.

    Science.gov (United States)

    Ferrara, T L; Clausen, P; Huber, D R; McHenry, C R; Peddemors, V; Wroe, S

    2011-02-01

    Although a strong correlation between jaw mechanics and prey selection has been demonstrated in bony fishes (Osteichthyes), how jaw mechanics influence feeding performance in cartilaginous fishes (Chondrichthyes) remains unknown. Hence, tooth shape has been regarded as a primary predictor of feeding behavior in sharks. Here we apply Finite Element Analysis (FEA) to examine form and function in the jaws of two threatened shark species, the great white (Carcharodon carcharias) and the sandtiger (Carcharias taurus). These species possess characteristic tooth shapes believed to reflect dietary preferences. We show that the jaws of sandtigers and great whites are adapted for rapid closure and generation of maximum bite force, respectively, and that these functional differences are consistent with diet and dentition. Our results suggest that in both taxa, insertion of jaw adductor muscles on a central tendon functions to straighten and sustain muscle fibers to nearly orthogonal insertion angles as the mouth opens. We argue that this jaw muscle arrangement allows high bite forces to be maintained across a wider range of gape angles than observed in mammalian models. Finally, our data suggest that the jaws of sub-adult great whites are mechanically vulnerable when handling large prey. In addition to ontogenetic changes in dentition, further mineralization of the jaws may be required to effectively feed on marine mammals. Our study is the first comparative FEA of the jaws for any fish species. Results highlight the potential of FEA for testing previously intractable questions regarding feeding mechanisms in sharks and other vertebrates. PMID:21129747

  18. Measurements of elastic modulus for human anterior lens capsule with atomic force microscopy: the effect of loading force.

    Science.gov (United States)

    Tsaousis, Konstantinos T; Karagiannidis, Panagiotis G; Kopsachilis, Nikolaos; Symeonidis, Chrysanthos; Tsinopoulos, Ioannis T; Karagkiozaki, Varvara; Lamprogiannis, Lampros P; Logothetidis, Stergios

    2014-06-01

    The purpose of the study was to appraise the effect of loading force magnitude on the determination of the elastic modulus of the anterior lens capsule through atomic force microscopy. Four human anterior lens capsules taken during phacoemulsification cataract surgery were studied, free of epithelial cells, with atomic force microscopy. For the experiment, five different indentation loading forces were applied to near areas of the specimen. Experimental data was exported and analyzed according to the Hertz model to obtain the Young's modulus with regards to the elastic behavior of the material. Force-distance curves were acquired by applying a load of 2, 5, 10, 20 and 30 nN. When examining the results it was evident that determination of Young's modulus of the anterior lens capsule is dependent on the loading force concerning the examined range. Loading forces of 10 and 20 nN led to results without significant difference (p > 0.05) and more reproducible (coefficients of variation 12.4 and 11.7 %, respectively). PMID:24037592

  19. Nanoscale spatially resolved simultaneous measurement of in-plane and out-of-plane force components on surfaces: a novel operational mode in atomic force microscopy

    Science.gov (United States)

    Watson, Gregory S.; Dinte, Bradley P.; Blach, Jolanta A.; Myhra, Sverre

    2002-11-01

    The atomic force microscope (AFM) allows investigation of the properties of surfaces and interfaces at atomic scale resolution. However, several different operational modes, (imaging, force versus distance and lateral force modes), need to be deployed in order to gain insight into the structure, tribological and mechanical properties. A new method, based on a variation of the force versus distance mode, has been developed. In essence, a coupling of the deformational modes of the probe is exploited whereby the tip is induced to undergo lateral travel in response to application of an out-of-plane force (and thus normal bending of the force-sensing lever). The lateral travel induces in-plane forces that are then measurable as a consequence of stimulation of the 'buckling' deformational mode of the lever. Due to the lever geometry, the technique offers an increase in resolution of an order of magnitude over existing AFM methods for measurement of atomic scale stick-slip events. In addition, the method allows measurement of the lateral deformation of the sample as well as scanner calibration. Outcomes will be demonstrated for atomically flat surfaces such as WTe2 and highly oriented pyrolytic graphite.

  20. Atomic force microscopy measurements of bacterial adhesion and biofilm formation onto clay-sized particles

    Science.gov (United States)

    Huang, Qiaoyun; Wu, Huayong; Cai, Peng; Fein, Jeremy B.; Chen, Wenli

    2015-11-01

    Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of -3.0 ± 0.4 nN and -330 ± 43 aJ (10-18 J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions.

  1. Atomic force microscopy measurements of bacterial adhesion and biofilm formation onto clay-sized particles.

    Science.gov (United States)

    Huang, Qiaoyun; Wu, Huayong; Cai, Peng; Fein, Jeremy B; Chen, Wenli

    2015-11-20

    Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of -3.0 ± 0.4 nN and -330 ± 43 aJ (10(-18) J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions.

  2. Merging Psychophysical and Psychometric Theory to Estimate Global Visual State Measures from Forced-Choices

    Science.gov (United States)

    Massof, Robert W.; Schmidt, Karen M.; Laby, Daniel M.; Kirschen, David; Meadows, David

    2013-09-01

    Visual acuity, a forced-choice psychophysical measure of visual spatial resolution, is the sine qua non of clinical visual impairment testing in ophthalmology and optometry patients with visual system disorders ranging from refractive error to retinal, optic nerve, or central visual system pathology. Visual acuity measures are standardized against a norm, but it is well known that visual acuity depends on a variety of stimulus parameters, including contrast and exposure duration. This paper asks if it is possible to estimate a single global visual state measure from visual acuity measures as a function of stimulus parameters that can represent the patient's overall visual health state with a single variable. Psychophysical theory (at the sensory level) and psychometric theory (at the decision level) are merged to identify the conditions that must be satisfied to derive a global visual state measure from parameterised visual acuity measures. A global visual state measurement model is developed and tested with forced-choice visual acuity measures from 116 subjects with no visual impairments and 560 subjects with uncorrected refractive error. The results are in agreement with the expectations of the model.

  3. Cervical vertebral body fusions in patients with skeletal deep bite.

    Science.gov (United States)

    Sonnesen, Liselotte; Kjaer, Inger

    2007-10-01

    Cervical column morphology was examined in 41 adult patients with a skeletal deep bite, 23 females aged 22-42 years (mean 27.9) and 18 males aged 21-44 years (mean 30.8) and compared with the cervical column morphology in an adult control group consisting of 21 subjects, 15 females, aged 23-40 years (mean 29.2 years) and six males aged 25-44 years (mean 32.8 years) with neutral occlusion and normal craniofacial morphology. None of the patients or control subjects had received orthodontic treatment. For each individual, a visual assessment of the cervical column and measurements of the cranial base angle, vertical craniofacial dimensions, and morphology of the mandible were performed on a profile radiograph. In the deep bite group, 41.5 per cent had fusion of the cervical vertebrae and 9.8 per cent posterior arch deficiency. The fusion always occurred between C2 and C3. No statistically significant gender differences were found in the occurrence of morphological characteristics of the cervical column (females 43.5 per cent, males 38.9 per cent). Morphological deviations of the cervical column occurred significantly more often in the deep bite group compared with the control group (P analysis showed that the vertical jaw relationship (P vertebrae (R(2) = 0.40).

  4. Measuring force transfers in the deep flexors of the musician's hand: theoretical analysis, clinical examples.

    Science.gov (United States)

    Leijnse, J N

    1997-09-01

    In the present paper the anatomical and functional interdependencies which regularly exist between the deep flexor tendons of the different fingers are modelled. The model results are validated by measurements on real hands. The results show that intertendinous force transfers may be caused by (i) coactivation of muscle fibres inserting in different tendons, and (ii) passive connections between tendons or muscle bellies. The coactivation is validated by the measuring results of a hand in which all intertendinous connections were surgically removed. The present models and measurements are currently used for diagnosis of hand problems in musicians at our hand clinic.

  5. Study on the AFM Force Spectroscopy method for elastic modulus measurement of living cells

    Science.gov (United States)

    Demichelis, A.; Pavarelli, S.; Mortati, L.; Sassi, G.; Sassi, M.

    2013-09-01

    The cell elasticity gives information about its pathological state and metastatic potential. The aim of this paper is to study the AFM Force Spectroscopy technique with the future goal of realizing a reference method for accurate elastic modulus measurement in the elasticity range of living cells. This biological range has not been yet explored with a metrological approach. Practical hints are given for the realization of a Sylgard elasticity scale. Systematic effects given by the sample curing thickness and nanoindenter geometry have been found with regards of the measured elastic modulus. AFM measurement reproducibility better than 20% is obtained in the entire investigated elastic modulus scale of 101 - 104 kPa.

  6. Force unfolding kinetics of RNA using optical tweezers. I. Effects of experimental variables on measured results

    CERN Document Server

    Wen, J -D; Li, P T X; Smith, S B; Bustamante, C; Ritort, F; Tinoco, I

    2007-01-01

    Experimental variables of optical tweezers instrumentation that affect RNA folding/unfolding kinetics were investigated. A model RNA hairpin, P5ab, was attached to two micron-sized beads through hybrid RNA/DNA handles; one bead was trapped by dual-beam lasers and the other was held by a micropipette. Several experimental variables were changed while measuring the unfolding/refolding kinetics, including handle lengths, trap stiffness, and modes of force applied to the molecule. In constant-force mode where the tension applied to the RNA was maintained through feedback control, the measured rate coefficients varied within 40% when the handle lengths were changed by 10 fold (1.1 to 10.2 Kbp); they increased by two- to three-fold when the trap stiffness was lowered to one third (from 0.1 to 0.035 pN/nm). In the passive mode, without feedback control and where the force applied to the RNA varied in response to the end-to-end distance change of the tether, the RNA hopped between a high-force folded-state and a low-...

  7. A new method of simultaneously measuring the applanation force and area as applied to tonometer prototype

    Science.gov (United States)

    Zhang, Xueyong; Ma, Jianguo

    2006-11-01

    A new method for simultaneous measuring the applanation force and area and a device based on this method are presented for intraocular pressure measurement. A photoelectric probe transducer acting as applalation area detector converted the diminished quantity of light returned from applanation surface of the cone prism into one electronic signal, and a micro strain gauge acting as applation force detector converted changing load related to the resilient force of the eye into another electronic signal. A 16-bit single-chip microprocessor with E2PROM in the electronic circuit played the role of a nucleus, which stored the program instructions and the interrelated data. Laboratory experiments were carried out on a stimulated cornea clamped in a Perspex chamber connected to a hydraulic manometer to obtain intraocular pressure at different levels. Preliminary trials were carried out comparing the values obtained with those of the Goldmann tonometer. Diminished quantity of the light is directly proportional to the applanation area of the cornea and the changing load detected by strain gauge is equated to the resilient force of the eye. A new kind of tonometer can be constructed based on this principle. Experimental results on a stimulated eyeball showed the present tonometer reading has good agreement with that of the Goldmann tonometer. Further study including clinical trials and application is required to evaluate the accuracy and usefulness of this method.

  8. Inverse combustion force estimation based on response measurements outside the combustion chamber and signal processing

    Science.gov (United States)

    Hosseini Fouladi, Mohammad; Mohd. Nor, Mohd. Jailani; Kamal Ariffin, Ahmad; Abdullah, Shahrir

    2009-11-01

    Exposure to vibration has various physiological effects on vehicle passengers. Engine is one of the main sources of vehicle vibration. The major causes of engine vibration are combustion forces transmitted through the pistons and connection rods. Evaluation of sources is the first step to attenuate this vibration. Assessment of these sources is not an easy task because internal parts of machinery are not accessible. Often, instrumentation for such systems is costly, time consuming and some modifications would be necessary. Aim of the first part of this paper was to validate an inverse technique and carry out mobility analysis on a vehicle crankshaft to achieve matrix of Frequency Response Functions (FRFs). Outcomes were implemented to reconstruct the applied force for single and multiple-input systems. In the second part, the validated inverse technique and FRFs were used to estimate piston forces of an operating engine. Bearings of crankshaft were chosen as nearest accessible parts to piston connecting rods. Accelerometers were connected to the bearings for response measurement during an ideal engine operation. These responses together with FRFs, which were estimated in the previous part, were utilised in the inverse technique. Tikhonov regularization was used to solve the ill-conditioned inverse system. Two methods, namely L-curve criterion and Generalized Cross Validation (GCV), were employed to find the regularization parameter for the Tikhonov method. The inverse problem was solved and piston forces applied to crankpins were estimated. Results were validated by pressure measurement inside a cylinder and estimating the corresponding combustion force. This validation showed that inverse technique and measurement outcomes were roughly in agreement. In presence of various noise, L-curve criterion conduces to more robust results compared to the GCV method. But in the absence of high correlation between sources ( f>600 HzHz), the GCV technique leads to more accurate

  9. The effects of food viscosity on bite size, bite effort and food intake

    NARCIS (Netherlands)

    Wijk, de R.A.; Zijlstra, N.; Mars, M.; Graaf, de C.; Prinz, J.F.

    2008-01-01

    Two studies investigated the effect of a food's viscosity on bite size, bite effort and food intake using a standardized protocol in which subjects sipped through a straw every 20 s for a period of 15 min from one of two products, a chocolate-flavored dairy drink and a chocolate-flavored dairy semi-

  10. Measurement of nonlinear normal modes using multi-harmonic stepped force appropriation and free decay

    Science.gov (United States)

    Ehrhardt, David A.; Allen, Matthew S.

    2016-08-01

    Nonlinear Normal Modes (NNMs) offer tremendous insight into the dynamic behavior of a nonlinear system, extending many concepts that are familiar in linear modal analysis. Hence there is interest in developing methods to experimentally and numerically determine a system's NNMs for model updating or simply to characterize its dynamic response. Previous experimental work has shown that a mono-harmonic excitation can be used to isolate a system's dynamic response in the neighborhood of a NNM along the main backbones of a system. This work shows that a multi-harmonic excitation is needed to isolate a NNM when well separated linear modes of a structure couple to produce an internal resonance. It is shown that one can tune the multiple harmonics of the input excitation using a plot of the input force versus the response velocity until the area enclosed by the force-velocity curve is minimized. Once an appropriated NNM is measured, one can increase the force level and retune the frequency to obtain a NNM at a higher amplitude or remove the excitation and measure the structure's decay down a NNM backbone. This work explores both methods using simulations and measurements of a nominally-flat clamped-clamped beam excited at a single point with a magnetic force. Numerical simulations are used to validate the method in a well defined environment and to provide comparison with the experimentally measured NNMs. The experimental results seem to produce a good estimate of two NNMs along their backbone and part of an internal resonance branch. Full-field measurements are then used to further explore the couplings between the underlying linear modes along the identified NNMs.

  11. Measuring the interaction force between a high temperature superconductor and a permanent magnet

    Science.gov (United States)

    Valenzuela, S. O.; Jorge, G. A.; Rodríguez, E.

    1999-11-01

    Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give rise to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction, which represents a promising field with regard to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt-textured YBa2Cu3O7 superconductor immersed in liquid nitrogen. The simple design of the experiments allows a fast and easy implementation in the advanced physics laboratory with a minimum cost. Actual levitation and suspension demonstrations can be done simultaneously as a help to interpret magnetic force measurements.

  12. Intramolecular Force Contrast and Dynamic Current-Distance Measurements at Room Temperature

    Science.gov (United States)

    Huber, F.; Matencio, S.; Weymouth, A. J.; Ocal, C.; Barrena, E.; Giessibl, F. J.

    2015-08-01

    Scanning probe microscopy can be used to probe the internal atomic structure of flat organic molecules. This technique requires an unreactive tip and has, until now, been demonstrated only at liquid helium and liquid nitrogen temperatures. We demonstrate intramolecular and intermolecular force contrast at room temperature on PTCDA molecules adsorbed on a Ag /Si (111 )-(√{3 }×√{3 }) surface. The oscillating force sensor allows us to dynamically measure the vertical decay constant of the tunneling current. The precision of this method is increased by quantifying the transimpedance of the current to voltage converter and accounting for the tip oscillation. This measurement yields a clear contrast between neighboring molecules, which we attribute to the different charge states.

  13. Effect of cholesterol on the physical properties of pulmonary surfactant films: Atomic force measurements study

    International Nuclear Information System (INIS)

    Atomic force measurements were performed on supported pulmonary surfactant (PS) films to address the effect of cholesterol on the physical properties of lung surfactant films. We recently found that cholesterol in excess of a physiological proportion abolishes surfactant function, and is the reason that surfactant fails to lower the surface tension upon compression. In this study, we investigated how the loss of mechanical stability observed earlier is related to the local mechanical properties of the film by local force measurements. The presence of 20% of cholesterol in bovine lipid extract surfactant (BLES) resulted in a decrease of the observed adhesive interaction, and an increase in rigidity of the film. We discuss the implication the increased rigidity might have on the functional failure of PS

  14. Harmonic force spectroscopy measures load-dependent kinetics of individual human β-cardiac myosin molecules

    Science.gov (United States)

    Sung, Jongmin; Nag, Suman; Mortensen, Kim I.; Vestergaard, Christian L.; Sutton, Shirley; Ruppel, Kathleen; Flyvbjerg, Henrik; Spudich, James A.

    2015-08-01

    Molecular motors are responsible for numerous cellular processes from cargo transport to heart contraction. Their interactions with other cellular components are often transient and exhibit kinetics that depend on load. Here, we measure such interactions using `harmonic force spectroscopy'. In this method, harmonic oscillation of the sample stage of a laser trap immediately, automatically and randomly applies sinusoidally varying loads to a single motor molecule interacting with a single track along which it moves. The experimental protocol and the data analysis are simple, fast and efficient. The protocol accumulates statistics fast enough to deliver single-molecule results from single-molecule experiments. We demonstrate the method's performance by measuring the force-dependent kinetics of individual human β-cardiac myosin molecules interacting with an actin filament at physiological ATP concentration. We show that a molecule's ADP release rate depends exponentially on the applied load, in qualitative agreement with cardiac muscle, which contracts with a velocity inversely proportional to external load.

  15. MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS

    Directory of Open Access Journals (Sweden)

    Mario Dobrilović

    2005-12-01

    Full Text Available Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a pre-condition for operation of the new detonator, and measurement of wave force is the first step in determining the sum of energy. The sum of energy is measured indirectly, based on two principles: movement sensors and strain.

  16. An urban Northeastern United States alligator bite.

    Science.gov (United States)

    Shepherd, Suzanne Moore; Shoff, William H

    2014-05-01

    Individuals who live and work in the Southeastern coastal range of the 3 US crocodilian carnivores, American alligators, American crocodiles, and caiman, understand the risks of reptile-human encounters. Individuals who live in other parts of the country maybe exposed through contact with exotic pets at private homes, small menageries, or petting zoos or from escaped or abandoned animals. During these encounters, individuals may be severely injured.Emergency medical services, law enforcement, and animal welfare workers in nonhabitat areas are usually not trained in the handling and safe removal of injured individuals from the scene when the reptile is present. The emergency management of large crocodilian injuries is similar to that of other major trauma; however, providers also must take into consideration the significant crush component potentially inflicted by the tremendous bite power and shaking inflicting during attacks by these large reptiles, appropriate antibiotic coverage for less common organisms that inhabit their mouths, and management of possible psychological distress, including posttraumatic stress disorder produced by such an unusual attack. Emergency physicians should support the development of a readily available national database of scientifically collect information on attacks to inform appropriate care and support efforts to explore responsible measures that the USDA Animal and Plant Health Inspection Service and other appropriate local, state, and federal agencies can take to ensure ethical and biologically sustainable management of our large reptiles, which also helps to ensure the safety of the public. PMID:24332253

  17. Measuring the interaction force between a high temperature superconductor and a permanent magnet

    OpenAIRE

    Valenzuela, S. O.; Jorge, G. A.; Rodriguez, E.

    1999-01-01

    Repulsive and attractive forces are both possible between a superconducting sample and a permanent magnet, and they can give place to magnetic levitation or free-suspension phenomena, respectively. We show experiments to quantify this magnetic interaction which represents a promising field regarding to short-term technological applications of high temperature superconductors. The measuring technique employs an electronic balance and a rare-earth magnet that induces a magnetic moment in a melt...

  18. Direct Measurement of Local Chromatin Fluidity Using Optical Trap Modulation Force Spectroscopy

    OpenAIRE

    Roopa, T.; Shivashankar, G. V.

    2006-01-01

    Chromatin assembly is condensed by histone tail-tail interactions and other nuclear proteins into a highly compact structure. Using an optical trap modulation force spectroscopy, we probe the effect of tail interactions on local chromatin fluidity. Chromatin fibers, purified from mammalian cells, are tethered between a microscope coverslip and a glass micropipette. Mechanical unzipping of tail interactions, using the micropipette, lead to the enhancement of local fluidity. This is measured us...

  19. Measurements of hydrodynamic forces on the impeller of the HPOTP of the SSME

    OpenAIRE

    Franz, Ron; Arndt, Norbert

    1986-01-01

    The references [1-4] provide a complete description of the facility. Briefly, the dynamometer, composed of two parallel plates connected by four strain gaged posts, is mounted between the impeller and the drive shaft. It measures the six components of a generalized hydrodynamic force vector {F} acting on the impeller. The impeller can be subject to whirling motion in an orbit eccentric to the volute center, in addition to the normal impeller rotation. Since the eccentric motion is in the late...

  20. Validity and reliability of pressure-measurement insoles for vertical ground reaction force assessment in field situations.

    Science.gov (United States)

    Koch, Markus; Lunde, Lars-Kristian; Ernst, Michael; Knardahl, Stein; Veiersted, Kaj Bo

    2016-03-01

    This study aimed to test the validity and reliability of pressure-measurement insoles (medilogic® insoles) when measuring vertical ground reaction forces in field situations. Various weights were applied to and removed from the insoles in static mechanical tests. The force values measured simultaneously by the insoles and force plates were compared for 15 subjects simulating work activities. Reliability testing during the static mechanical tests yielded an average interclass correlation coefficient of 0.998. Static loads led to a creeping pattern of the output force signal. An individual load response could be observed for each insole. The average root mean square error between the insoles and force plates ranged from 6.6% to 17.7% in standing, walking, lifting and catching trials and was 142.3% in kneeling trials. The results show that the use of insoles may be an acceptable method for measuring vertical ground reaction forces in field studies, except for kneeling positions.

  1. Force measurements of flexible tandem wings in hovering and forward flights

    International Nuclear Information System (INIS)

    Aerodynamic forces, power consumptions and efficiencies of flexible and rigid tandem wings undergoing combined plunging/pitching motion were measured in a hovering flight and two forward flights with Strouhal numbers of 0.6 and 0.3. Three flexible dragonfly-like tandem wing models termed Wing I, Wing II, and Wing III which are progressively less flexible, as well as a pair of rigid wings as the reference were operated at three phase differences of 0°, 90° and 180°. The results showed that both the flexibility and phase difference have significant effects on the aerodynamic performances. In both hovering and forward flights at a higher oscillation frequency of 1 Hz (St = 0.6), the Wing III model outperformed the other wing models with larger total horizontal force coefficient and efficiency. In forward flight at the lower frequency of 0.5 Hz (St = 0.3), Wing III, rigid wings and Wing II models performed best at 0°, 90° and 180° phase difference, respectively. From the time histories of force coefficients of fore- and hind-wings, different peak values, phase lags, and secondary peaks were found to be the important reasons to cause the differences in the average horizontal force coefficients. Particle image velocimetry and deformation measurements were performed to provide the insights into how the flexibility affects the aerodynamic performance of the tandem wings. The spanwise bending deformation was found to contribute to the horizontal force, by offering a more beneficial position to make LEV more attached to the wing model in both hovering and forward flights, and inducing a higher-velocity region in forward flight. (paper)

  2. Adhesion force measurements on the two wax layers of the waxy zone in Nepenthes alata pitchers.

    Science.gov (United States)

    Gorb, Elena V; Purtov, Julia; Gorb, Stanislav N

    2014-06-03

    The wax coverage of the waxy zone in Nepenthes alata pitchers consists of two clearly distinguishable layers, designated the upper and lower wax layers. Since these layers were reported to reduce insect attachment, they were considered to have anti-adhesive properties. However, no reliable adhesion tests have been performed with these wax layers. In this study, pull-off force measurements were carried out on both wax layers of the N. alata pitcher and on two reference polymer surfaces using deformable polydimethylsiloxane half-spheres as probes. To explain the results obtained, roughness measurements were performed on test surfaces. Micro-morphology of both surface samples and probes tested was examined before and after experiments. Pull-off forces measured on the upper wax layer were the lowest among surfaces tested. Here, contamination of probes by wax crystals detached from the pitcher surface was found. This suggests that low insect attachment on the upper wax layer is caused primarily by the breaking off of wax crystals from the upper wax layer, which acts as a separation layer between the insect pad and the pitcher surface. High adhesion forces obtained on the lower wax layer are explained by the high deformability of probes and the particular roughness of the substrate.

  3. Thin-film dielectric elastomer sensors to measure the contraction force of smooth muscle cells

    Science.gov (United States)

    Araromi, O.; Poulin, A.; Rosset, S.; Favre, M.; Giazzon, M.; Martin-Olmos, C.; Liley, M.; Shea, H.

    2015-04-01

    The development of thin-film dielectric elastomer strain sensors for the characterization of smooth muscle cell (SMC) contraction is presented here. Smooth muscle disorders are an integral part of diseases such as asthma and emphysema. Analytical tools enabling the characterization of SMC function i.e. contractile force and strain, in a low-cost and highly parallelized manner are necessary for toxicology screening and for the development of new and more effective drugs. The main challenge with the design of such tools is the accurate measurement of the extremely low contractile cell forces expected as a result of SMC monolayer contraction (as low as ~ 100 μN). Our approach utilizes ultrathin (~5 μm) and soft elastomer membranes patterned with elastomer-carbon composite electrodes, onto which the SMCs are cultured. The cell contraction induces an in-plane strain in the elastomer membrane, predicted to be in the order 1 %, which can be measured via the change in the membrane capacitance. The cell force can subsequently be deduced knowing the mechanical properties of the elastomer membrane. We discuss the materials and fabrication methods selected for our system and present preliminary results indicating their biocompatibility. We fabricate functional capacitive senor prototypes with good signal stability over the several hours (~ 0.5% variation). We succeed in measuring in-plane strains of 1 % with our fabricated devices with good repeatability and signal to noise ratio.

  4. Effects of non-Gaussian Brownian motion on direct force optical tweezers measurements of the electrostatic forces between pairs of colloidal particles.

    Science.gov (United States)

    Raudsepp, Allan; A K Williams, Martin; B Hall, Simon

    2016-07-01

    Measurements of the electrostatic force with separation between a fixed and an optically trapped colloidal particle are examined with experiment, simulation and analytical calculation. Non-Gaussian Brownian motion is observed in the position of the optically trapped particle when particles are close and traps weak. As a consequence of this motion, a simple least squares parameterization of direct force measurements, in which force is inferred from the displacement of an optically trapped particle as separation is gradually decreased, contains forces generated by the rectification of thermal fluctuations in addition to those originating directly from the electrostatic interaction between the particles. Thus, when particles are close and traps weak, simply fitting the measured direct force measurement to DLVO theory extracts parameters with modified meanings when compared to the original formulation. In such cases, however, physically meaningful DLVO parameters can be recovered by comparing the measured non-Gaussian statistics to those predicted by solutions to Smoluchowski's equation for diffusion in a potential. PMID:27439853

  5. Measurement of the axial force during primary peristalsis in the oesophagus using a novel electrical impedance technology.

    Science.gov (United States)

    Gravesen, F H; McMahon, B P; Drewes, A M; Gregersen, H

    2008-03-01

    The oesophagus serves to transport food and fluid from the pharynx to the stomach. Oesophageal function is usually evaluated by means of manometry which is a proxy of the force in the radial direction. However, force measurements in the axial direction will provide a better measure of oesophageal transport function. The aim of this study was to develop a probe based on electrical impedance measurements to quantify the axial force generated by oesophageal contractions, i.e. probe elongation was associated with the axial force. Calibration with weights up to 200 g was done. The dispersion, creep, temperature and bending dependence were studied at the bench. Subsequently, the probe was tested in vivo in a healthy human volunteer. The probe showed good reproducibility and the dispersion was measurements (P = 0.038) but not with manometric measurements. In conclusion, the new technique measures axial force in the oesophagus and may in the future provide valuable information about oesophageal function. PMID:18367813

  6. Kinetic peak vertical force measurement in cats afflicted by coxarthritis: data management and acquisition protocols.

    Science.gov (United States)

    Moreau, Maxim; Guillot, Martin; Pelletier, Jean-Pierre; Martel-Pelletier, Johanne; Troncy, Eric

    2013-08-01

    The management of the peak vertical force (PVF) measurement needs to be determined in coxarthritis cats. Six privately-owned coxarthritis cats were conditioned to trot across a floor mat-based plantar force measurement system. Hind limbs PVF was measured on level ground at day one (D1), D8, D42, and D84. Measurements were repeated after 10 min treadmill exercise (D1), trotting on an inclined (13°) plane (D42) and after stair climbing exercise (D84). Test-retest reliability between D1 and D8 was good (intraclass coefficient of correlation of 0.8). Coefficients of dispersion (within-subject and between-subject) were <15% using the lowest hind limb PVF value. Only stair climbing exercise positively affected sample and effect size estimates. To limit the dispersion of data, the measurement of PVF should be managed using the lowest hind limb PVF value. In addition, PVF should be measured following stair climbing to optimise sample and effect sizes and to preserve statistical power.

  7. Measuring the loss tangent of polymer materials with atomic force microscopy based methods

    International Nuclear Information System (INIS)

    Atomic force microscopy (AFM) quantitatively maps viscoelastic parameters of polymers on the nanoscale by several methods. The loss tangent, the ratio between dissipated and stored energy, was measured on a blend of thermoplastic polymer materials by a dynamic contact method, contact resonance, and by a recently developed loss tangent measurement by amplitude modulation AFM. Contact resonance measurements were performed both with dual AC resonance tracking and band excitation (BE), allowing for a reference-free measurement of the loss tangent. Amplitude modulation AFM was performed where a recent interpretation of the phase signal under certain operating conditions allows for the loss tangent to be calculated. The loss tangent measurements were compared with values expected from time–temperature superposed frequency-dependent dynamical mechanical curves of materials and reveal that the loss tangents determined from the BE contact resonance method provide the most accurate values. (paper)

  8. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement

    Science.gov (United States)

    Xie, Yu; Zhou, Yunlei; Lin, Yuzi; Wang, Lingyun; Xi, Wenming

    2016-01-01

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach. PMID:27058545

  9. Measurements of forces produced by the mitotic spindle using optical tweezers.

    Science.gov (United States)

    Ferraro-Gideon, Jessica; Sheykhani, Rozhan; Zhu, Qingyuan; Duquette, Michelle L; Berns, Michael W; Forer, Arthur

    2013-05-01

    We used a trapping laser to stop chromosome movements in Mesostoma and crane-fly spermatocytes and inward movements of spindle poles after laser cuts across Potorous tridactylus (rat kangaroo) kidney (PtK2) cell half-spindles. Mesostoma spermatocyte kinetochores execute oscillatory movements to and away from the spindle pole for 1-2 h, so we could trap kinetochores multiple times in the same spermatocyte. The trap was focused to a single point using a 63× oil immersion objective. Trap powers of 15-23 mW caused kinetochore oscillations to stop or decrease. Kinetochore oscillations resumed when the trap was released. In crane-fly spermatocytes trap powers of 56-85 mW stopped or slowed poleward chromosome movement. In PtK2 cells 8-mW trap power stopped the spindle pole from moving toward the equator. Forces in the traps were calculated using the equation F = Q'P/c, where P is the laser power and c is the speed of light. Use of appropriate Q' coefficients gave the forces for stopping pole movements as 0.3-2.3 pN and for stopping chromosome movements in Mesostoma spermatocytes and crane-fly spermatocytes as 2-3 and 6-10 pN, respectively. These forces are close to theoretical calculations of forces causing chromosome movements but 100 times lower than the 700 pN measured previously in grasshopper spermatocytes. PMID:23485565

  10. Preparation and friction force microscopy measurements of immiscible, opposing polymer brushes.

    Science.gov (United States)

    de Beer, Sissi; Kutnyanszky, Edit; Müser, Martin H; Vancso, G Julius

    2014-01-01

    Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(N-isopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone. PMID:25590429

  11. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement.

    Science.gov (United States)

    Xie, Yu; Zhou, Yunlei; Lin, Yuzi; Wang, Lingyun; Xi, Wenming

    2016-01-01

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach. PMID:27058545

  12. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement.

    Science.gov (United States)

    Xie, Yu; Zhou, Yunlei; Lin, Yuzi; Wang, Lingyun; Xi, Wenming

    2016-04-06

    Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach.

  13. Development of a Microforce Sensor and Its Array Platform for Robotic Cell Microinjection Force Measurement

    Directory of Open Access Journals (Sweden)

    Yu Xie

    2016-04-01

    Full Text Available Robot-assisted cell microinjection, which is precise and can enable a high throughput, is attracting interest from researchers. Conventional probe-type cell microforce sensors have some real-time injection force measurement limitations, which prevent their integration in a cell microinjection robot. In this paper, a novel supported-beam based cell micro-force sensor with a piezoelectric polyvinylidine fluoride film used as the sensing element is described, which was designed to solve the real-time force-sensing problem during a robotic microinjection manipulation, and theoretical mechanical and electrical models of the sensor function are derived. Furthermore, an array based cell-holding device with a trapezoidal microstructure is micro-fabricated, which serves to improve the force sensing speed and cell manipulation rates. Tests confirmed that the sensor showed good repeatability and a linearity of 1.82%. Finally, robot-assisted zebrafish embryo microinjection experiments were conducted. These results demonstrated the effectiveness of the sensor working with the robotic cell manipulation system. Moreover, the sensing structure, theoretical model, and fabrication method established in this study are not scale dependent. Smaller cells, e.g., mouse oocytes, could also be manipulated with this approach.

  14. Reconstruction of Energy Surfaces from Friction Force Microscopy Measurements with the Jarzynski Equality

    Science.gov (United States)

    Berkovich, Ronen; Klafter, Joseph; Urbakh, Michael

    Free energy is one of the most fundamental thermodynamic functions, determining relative phase stability and serving as a generating function for other thermodynamic quantities. The calculation of free energies is a challenging enterprise. In equilibrium statistical mechanics, the free energy is related to the canonical partition function. The partition function itself involves integrations over all degrees of freedom in the system and, in most cases, cannot be easily calculated directly. In 1997, Jarzynski proved a remarkable equality that allows computing the equilibrium free-energy difference between two states from the probability distribution of the nonequilibrium work done on the system to switch between the two states. The Jarzynski equality provides a powerful free-energy difference estimator from a set of irreversible experiments. This method is closely related to free-energy perturbation approach, which is also a computational technique for estimating free-energy differences. The ability to map potential profiles and topologies is of major significance to areas as diverse as biological recognition and nanoscale friction. This capability has been demonstrated for frictional studies where a force between the tip of the scanning force microscope and the surface is probed. The surface free-energy corrugation produces a detectable friction forces. Thus, friction force microscopy (FFM) should be able to discriminate between energetically different areas on the probed surface. Here, we apply the Jarzynski equality for the analysis of FFM measurements and thus obtain a variation of the free energy along a surface.

  15. Note: Measurement system for the radiative forcing of greenhouse gases in a laboratory scale.

    Science.gov (United States)

    Kawamura, Yoshiyuki

    2016-01-01

    The radiative forcing of the greenhouse gases has been studied being based on computational simulations or the observation of the real atmosphere meteorologically. In order to know the greenhouse effect more deeply and to study it from various viewpoints, the study on it in a laboratory scale is important. We have developed a direct measurement system for the infrared back radiation from the carbon dioxide (CO2) gas. The system configuration is similar with that of the practical earth-atmosphere-space system. Using this system, the back radiation from the CO2 gas was directly measured in a laboratory scale, which roughly coincides with meteorologically predicted value. PMID:26827362

  16. Note: Measurement system for the radiative forcing of greenhouse gases in a laboratory scale

    International Nuclear Information System (INIS)

    The radiative forcing of the greenhouse gases has been studied being based on computational simulations or the observation of the real atmosphere meteorologically. In order to know the greenhouse effect more deeply and to study it from various viewpoints, the study on it in a laboratory scale is important. We have developed a direct measurement system for the infrared back radiation from the carbon dioxide (CO2) gas. The system configuration is similar with that of the practical earth-atmosphere-space system. Using this system, the back radiation from the CO2 gas was directly measured in a laboratory scale, which roughly coincides with meteorologically predicted value

  17. Characterization of thermoelectric devices by laser induced Seebeck electromotive force (LIS-EMF) measurement

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Luis-David Patino [Universite de Bordeaux 1, Centre de Physique Moleculaire Optique et Hertzienne, 351, cours de la liberation, 33405 Talence (France); Dilhaire, Stefan [Universite de Bordeaux 1, Centre de Physique Moleculaire Optique et Hertzienne, 351, cours de la liberation, 33405 Talence (France); Grauby, Stephane [Universite de Bordeaux 1, Centre de Physique Moleculaire Optique et Hertzienne, 351, cours de la liberation, 33405 Talence (France); Salhi, M Amine [Universite de Bordeaux 1, Centre de Physique Moleculaire Optique et Hertzienne, 351, cours de la liberation, 33405 Talence (France); Ezzahri, Younes [Universite de Bordeaux 1, Centre de Physique Moleculaire Optique et Hertzienne, 351, cours de la liberation, 33405 Talence (France); Claeys, Wilfrid [Universite de Bordeaux 1, Centre de Physique Moleculaire Optique et Hertzienne, 351, cours de la liberation, 33405 Talence (France); Batsale, Jean-Christophe [Laboratoire TREFLE, Esplanade des Arts et Metiers, 33405 Talence Cedex (France)

    2005-05-21

    An in-depth study related to a new method of characterizing properties in thermoelectrics is proposed in this paper. This technique is appropriate for single or multi-layered thermoelectric devices. A modulated laser beam is used as a heater in order to generate a Seebeck electromotive force (EMF). The laser beam, line shaped, can be focused at any location along the sample surface, allowing spatially resolved measurements. Seebeck EMF measurements, associated with a versatile model based on the thermal quadrupoles method, allow determination of the sample Seebeck EMF profile and identifying of the sample thermal contact resistances, and should be useful for identification of devices and material thermoelectric properties.

  18. Characterization of thermoelectric devices by laser induced Seebeck electromotive force (LIS-EMF) measurement

    Science.gov (United States)

    Patiño Lopez, Luis-David; Dilhaire, Stefan; Grauby, Stéphane; Amine Salhi, M.; Ezzahri, Younès; Claeys, Wilfrid; Batsale, Jean-Christophe

    2005-05-01

    An in-depth study related to a new method of characterizing properties in thermoelectrics is proposed in this paper. This technique is appropriate for single or multi-layered thermoelectric devices. A modulated laser beam is used as a heater in order to generate a Seebeck electromotive force (EMF). The laser beam, line shaped, can be focused at any location along the sample surface, allowing spatially resolved measurements. Seebeck EMF measurements, associated with a versatile model based on the thermal quadrupoles method, allow determination of the sample Seebeck EMF profile and identifying of the sample thermal contact resistances, and should be useful for identification of devices and material thermoelectric properties.

  19. Characterization of thermoelectric devices by laser induced Seebeck electromotive force (LIS-EMF) measurement

    International Nuclear Information System (INIS)

    An in-depth study related to a new method of characterizing properties in thermoelectrics is proposed in this paper. This technique is appropriate for single or multi-layered thermoelectric devices. A modulated laser beam is used as a heater in order to generate a Seebeck electromotive force (EMF). The laser beam, line shaped, can be focused at any location along the sample surface, allowing spatially resolved measurements. Seebeck EMF measurements, associated with a versatile model based on the thermal quadrupoles method, allow determination of the sample Seebeck EMF profile and identifying of the sample thermal contact resistances, and should be useful for identification of devices and material thermoelectric properties

  20. An Activation Force-based Affinity Measure for Analyzing Complex Networks

    OpenAIRE

    Jun Guo; Hanliang Guo; Zhanyi Wang

    2011-01-01

    Affinity measure is a key factor that determines the quality of the analysis of a complex network. Here, we introduce a type of statistics, activation forces, to weight the links of a complex network and thereby develop a desired affinity measure. We show that the approach is superior in facilitating the analysis through experiments on a large-scale word network and a protein-protein interaction (PPI) network consisting of ∼5,000 human proteins. The experiment on the word network verifies tha...

  1. Note: Measurement system for the radiative forcing of greenhouse gases in a laboratory scale.

    Science.gov (United States)

    Kawamura, Yoshiyuki

    2016-01-01

    The radiative forcing of the greenhouse gases has been studied being based on computational simulations or the observation of the real atmosphere meteorologically. In order to know the greenhouse effect more deeply and to study it from various viewpoints, the study on it in a laboratory scale is important. We have developed a direct measurement system for the infrared back radiation from the carbon dioxide (CO2) gas. The system configuration is similar with that of the practical earth-atmosphere-space system. Using this system, the back radiation from the CO2 gas was directly measured in a laboratory scale, which roughly coincides with meteorologically predicted value.

  2. Note: Measurement system for the radiative forcing of greenhouse gases in a laboratory scale

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Yoshiyuki [Department of Intelligent Mechanical Engineering, Fukuoka Institute of Technology, 3-30-1 Wajirohigashi, Higashiku, Fukuoka 811-0295 (Japan)

    2016-01-15

    The radiative forcing of the greenhouse gases has been studied being based on computational simulations or the observation of the real atmosphere meteorologically. In order to know the greenhouse effect more deeply and to study it from various viewpoints, the study on it in a laboratory scale is important. We have developed a direct measurement system for the infrared back radiation from the carbon dioxide (CO{sub 2}) gas. The system configuration is similar with that of the practical earth-atmosphere-space system. Using this system, the back radiation from the CO{sub 2} gas was directly measured in a laboratory scale, which roughly coincides with meteorologically predicted value.

  3. Reliable measurement of elastic modulus of cells by nanoindentation in an atomic force microscope

    KAUST Repository

    Zhou, Zhoulong

    2012-04-01

    The elastic modulus of an oral cancer cell line UM1 is investigated by nanoindentation in an atomic force microscope with a flat-ended tip. The commonly used Hertzian method gives apparent elastic modulus which increases with the loading rate, indicating strong effects of viscoelasticity. On the contrary, a rate-jump method developed for viscoelastic materials gives elastic modulus values which are independent of the rate-jump magnitude. The results show that the rate-jump method can be used as a standard protocol for measuring elastic stiffness of living cells, since the measured values are intrinsic properties of the cells. © 2011 Elsevier Ltd.

  4. Magnetic vortex chirality determination via local hysteresis loops measurements with magnetic force microscopy.

    Science.gov (United States)

    Coïsson, Marco; Barrera, Gabriele; Celegato, Federica; Manzin, Alessandra; Vinai, Franco; Tiberto, Paola

    2016-01-01

    Magnetic vortex chirality in patterned square dots has been investigated by means of a field-dependent magnetic force microscopy technique that allows to measure local hysteresis loops. The chirality affects the two loop branches independently, giving rise to curves that have different shapes and symmetries as a function of the details of the magnetisation reversal process in the square dot, that is studied both experimentally and through micromagnetic simulations. The tip-sample interaction is taken into account numerically, and exploited experimentally, to influence the side of the square where nucleation of the vortex preferably occurs, therefore providing a way to both measure and drive chirality with the present technique. PMID:27426442

  5. Spring constants and adhesive properties of native bacterial biofilm cells measured by atomic force microscopy.

    Science.gov (United States)

    Volle, C B; Ferguson, M A; Aidala, K E; Spain, E M; Núñez, M E

    2008-11-15

    Bacterial biofilms were imaged by atomic force microscopy (AFM), and their elasticity and adhesion to the AFM tip were determined from a series of tip extension and retraction cycles. Though the five bacterial strains studied included both Gram-negative and -positive bacteria and both environmental and laboratory strains, all formed simple biofilms on glass surfaces. Cellular spring constants, determined from the extension portion of the force cycle, varied between 0.16+/-0.01 and 0.41+/-0.01 N/m, where larger spring constants were measured for Gram-positive cells than for Gram-negative cells. The nonlinear regime in the extension curve depended upon the biomolecules on the cell surface: the extension curves for the smooth Gram-negative bacterial strains with the longest lipopolysaccharides on their surface had a larger nonlinear region than the rough bacterial strain with shorter lipopolysaccharides on the surface. Adhesive forces between the retracting silicon nitride tip and the cells varied between cell types in terms of the force components, the distance components, and the number of adhesion events. The Gram-negative cells' adhesion to the tip showed the longest distance components, sometimes more than 1 microm, whereas the shortest distance adhesion events were measured between the two Gram-positive cell types and the tip. Fixation of free-swimming planktonic cells by NHS and EDC perturbed both the elasticity and the adhesive properties of the cells. Here we consider the biochemical meaning of the measured physical properties of simple biofilms and implications to the colonization of surfaces in the first stages of biofilm formation. PMID:18815013

  6. VARIABILITY OF FORCED OSCILLATION (SIEMENS SIREGNOST FD-5) MEASUREMENTS OF TOTAL RESPIRATORY RESISTANCE IN PATIENTS AND HEALTHY-SUBJECTS

    NARCIS (Netherlands)

    GIMENO, F; VANDERWEELE, LT; KOETER, GH; DEMONCHY, JGR; VANALTENA, R

    1993-01-01

    The reproducibility of total respiratory resistance (R(rs)) measured with a simplified forced oscillatory method (Siemens Siregnost FD 5) was measured and compared with that of slow inspiratory vital capacity (IVC) and forced expiratory volume in one second (FEV1). The former technique has the advan

  7. Visualized Multiprobe Electrical Impedance Measurements with STM Tips Using Shear Force Feedback Control

    Directory of Open Access Journals (Sweden)

    Luis Botaya

    2016-05-01

    Full Text Available Here we devise a multiprobe electrical measurement system based on quartz tuning forks (QTFs and metallic tips capable of having full 3D control over the position of the probes. The system is based on the use of bent tungsten tips that are placed in mechanical contact (glue-free solution with a QTF sensor. Shear forces acting in the probe are measured to control the tip-sample distance in the Z direction. Moreover, the tilting of the tip allows the visualization of the experiment under the optical microscope, allowing the coordination of the probes in X and Y directions. Meanwhile, the metallic tips are connected to a current–voltage amplifier circuit to measure the currents and thus the impedance of the studied samples. We discuss here the different aspects that must be addressed when conducting these multiprobe experiments, such as the amplitude of oscillation, shear force distance control, and wire tilting. Different results obtained in the measurement of calibration samples and microparticles are presented. They demonstrate the feasibility of the system to measure the impedance of the samples with a full 3D control on the position of the nanotips.

  8. A precision measurement of the neutron2. Probing the color force

    Energy Technology Data Exchange (ETDEWEB)

    Posik, Matthew R. [Temple Univ., Philadelphia, PA (United States)

    2014-01-01

    The g2 nucleon spin-dependent structure function measured in electron deep inelastic scattering contains information beyond the simple parton model description of the nucleon. It provides insight into quark-gluon correlations and a path to access the confining local color force a struck quark experiences just as it is hit by the virtual photon due to the remnant di-quark. The quantity d2, a measure of this local color force, has its information encoded in an x2 weighted integral of a linear combination of spin structure functions g1 and g2 and thus is dominated by the valence-quark region at large momentum fraction x. To date, theoretical calculations and experimental measurements of the neutron d2 differ by about two standard deviations. Therefore, JLab experiment E06-014, performed in Hall A, made a precision measurement of this quantity at two mean four momentum transfers values of 3.21 and 4.32 GeV2. Double spin asymmetries and absolute cross-sections were measured in both DIS and resonance regions by scattering longitudinally polarized electrons at beam energies of 4.74 and 5.89 GeV from a longitudinally and transversely polarized 3He target. Results for the absolute cross-sections and spin structure functions on 3He will be presented in the dissertation, as well as results for the neutron d2 and extracted color forces.

  9. Formation of an artificial blood vessel: adhesion force measurements with optical tweezers

    Science.gov (United States)

    Knoener, Gregor; Campbell, Julie H.; Heckenberg, Norman R.; Rubinsztein-Dunlop, Halina

    2004-10-01

    We are investigating the formation of a tissue capsule around a foreign body. This tissue capsule can be used as an autologous graft for the replacement of diseased blood vessels or for bypass surgery. The graft is grown in the peritoneal cavity of the recipient and the formation starts with the adhesion of cells to the foreign body. We identify the cell type and measure the adhesion of these cells to foreign materials using optical tweezers. Cell adhesion to macroscopic samples and microspheres is investigated. No difference in the adhesion force was measurable for polyethylene, silicon and Tygon on a scale accessible to optical tweezers. The density of adherent cells was found to vary strongly, being highest on polyethylene. The mean rupture forces for cell-microsphere adhesion ranged from 24 to 39 pN and changed upon preadsorption of bovine serum albumin. For plain microspheres, the highest mean rupture force was found for PMMA, which also showed the highest adhesion probability for the cell-microsphere interaction.

  10. Lock-in technique for concurrent measurement of adhesion and friction with the scanning force microscope

    Science.gov (United States)

    Krotil, H.-U.; Stifter, Th.; Marti, O.

    2001-01-01

    Regardless of all the great progress in new scanning probe microscopy techniques, the concurrent measurement of adhesive and frictional forces with local resolution using scanning force microscopy (SFM) has not been possible until now. In this paper, we present a novel scanning probe microscopy mode, called combined dynamic x mode or CODYMode®. In CODYMode® SFM at least two oscillations with sufficiently different frequencies and amplitudes are superimposed and interact with the sample surface. This enables the concurrent measurement of the topography, adhesive and frictional forces beside further mechanical surface properties of the sample. By means of the characterization of plasma treated biaxially oriented polypropylene foils the benefits of the new modulation technique are pointed out where common SFM techniques are not adequate. As second application high-velocity friction experiments (in the range of several centimeters per second) on silicon under controlled environmental conditions are introduced and the role of the native water film on it is discussed under friction and viscoelastic aspects.

  11. Biophysical Measurements of Cells, Microtubules, and DNA with an Atomic Force Microscope

    CERN Document Server

    Devenica, Luka M; Cabrejo, Raysa; Kurek, Matthew; Deveney, Edward F; Carter, Ashley R

    2015-01-01

    Atomic force microscopes (AFMs) are ubiquitous in research laboratories and have recently been priced for use in teaching laboratories. Here we review several AFM platforms (Dimension 3000 by Digital Instruments, EasyScan2 by Nanosurf, ezAFM by Nanomagnetics, and TKAFM by Thorlabs) and describe various biophysical experiments that could be done in the teaching laboratory using these instruments. In particular, we focus on experiments that image biological materials and quantify biophysical parameters: 1) imaging cells to determine membrane tension, 2) imaging microtubules to determine their persistence length, 3) imaging the random walk of DNA molecules to determine their contour length, and 4) imaging stretched DNA molecules to measure the tensional force.

  12. Torsion pendulum facility for direct force measurements of LISA GRS related disturbances

    CERN Document Server

    Carbone, L; Ciani, G; Dolesi, R; Hüller, M; Tombolato, D; Vitale, S; Weber, W J

    2007-01-01

    A four mass torsion pendulum facility for testing of the LISA GRS is under development in Trento. With a LISA-like test mass suspended off-axis with respect to the pendulum fiber, the facility allows for a direct measurement of surface force disturbances arising in the GRS. We present here results with a prototype pendulum integrated with very large-gap sensors, which allows an estimate of the intrinsic pendulum noise floor in the absence of sensor related force noise. The apparatus has shown a torque noise near to its mechanical thermal noise limit, and would allow to place upper limits on GRS related disturbances with a best sensitivity of 300 fN/Hz^(1/2) at 1mHz, a factor 50 from the LISA goal. Also, we discuss the characterization of the gravity gradient noise, one environmental noise source that could limit the apparatus performances, and report on the status of development of the facility.

  13. Quantitative measurement of void fraction in a forced convective flow boiling by using neutron radiography

    International Nuclear Information System (INIS)

    The void fraction in a forced convective flow boiling is very important information for understanding the characteristics of the boiling two-phase flow. Consequently, many experimental investigations have been carried out to obtain the local void fraction so far, but the detail data among the whole of the test-section has not been enough. Especially, the data under subcooled condition are quite limited. In this study, the void fraction distribution in a forced convective boiling was quantitatively measured by using the thermal neutron radiography. These results were compared with several existing void fraction correlations. Although these correlations show a good agreements with experimental results under low heat flux condition, there is no suitable correlation to estimate the void fraction under non-thermal equilibrium condition. (author)

  14. Electrical resistivity of polypyrrole nanotube measured by conductive scanning probe microscope: The role of contact force

    Science.gov (United States)

    Park, J. G.; Lee, S. H.; Kim, B.; Park, Y. W.

    2002-12-01

    Polypyrrole (PPy) nanotubes were synthesized using the pores of track-etched polycarbonate membrane as a template. Its size depends on the pore diameter of template, range from 50 to 200 nm. Direct I-V measurements of PPy nanotube (diameter of 120 nm) deposited on Au were done using a metal-coated tapping-mode atomic-force-microscope tip. Linear I-V characteristics are observed, and the resistance is decreased as the contact force is increased. Using the Hertz model, the elastic modulus E and electrical resistivity ρ are estimated to be E˜1 GPa and ρ˜1 Ωcm. These values are consistent with those obtained in bulk PPy film.

  15. Bug bites and stings: When to see a dermatologist

    Medline Plus

    Full Text Available ... bug bite or sting could turn into something serious – particularly if you have been bitten or stung ... bite: This could be a sign of Lyme disease, which should be treated with antibiotics. A fever ...

  16. Taking the Bite out of Bruxism (For Kids)

    Science.gov (United States)

    ... Dictionary of Medical Words En Español What Other Kids Are Reading Movie: Digestive System Winter Sports: Sledding, ... Taking the Bite Out of Bruxism KidsHealth > For Kids > Taking the Bite Out of Bruxism Print A ...

  17. Zika's Delivery Via Mosquito Bite May Boost Its Effect

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_159484.html Zika's Delivery Via Mosquito Bite May Boost Its Effect ... The inflammation caused by a mosquito bite helps Zika and other viruses spread through the body more ...

  18. Development of a Hybrid Atomic Force Microscopic Measurement System Combined with White Light Scanning Interferometry

    Directory of Open Access Journals (Sweden)

    Xiaotang Hu

    2011-12-01

    Full Text Available A hybrid atomic force microscopic (AFM measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system’s dynamic response, the frequency modulation (FM mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system’s good measurement performance and feasibility of the hybrid measurement method.

  19. Defect localization in fibre-reinforced composites by computing external volume forces from surface sensor measurements

    International Nuclear Information System (INIS)

    We suggest a prospective method for detecting and visualizing defects in fibre-reinforced composites by computing external volume forces from measurements acquired by sensors that are integrated on the surface of the structure. Anisotropic materials like carbon fibre-reinforced composites are widely used in light weight construction which can exhibit damages that are not optically detectable. The key idea of our method is the interpretation of defects in such structures as if they were induced by an external volume force. This idea is based on the observation that a propagating elastic wave interferes with a damaged area by reflecting the wave. In that sense a damage can be seen as an additional source. Thus identifying the external volume force which has caused this wave is supposed to reveal the location of the defect. This approach leads to the inverse problem of determining the inhomogeneity of a hyperbolic initial-boundary value problem. We tackle this ill-posed problem by minimizing a Tikhonov functional which takes the oberservation points of our surface measurements into account. In the article we address the solvability of the direct problem, state and analyze the PDE-based optimization problem that aims for computing the external force and develop a numerical realization of its solution using the conjugate gradient method. First numerical results for a simple model case with different sensor adjustments show that the defects in fact are detectable. In that sense this article might be seen as starting point of future research which should comprehend deeper numerical studies and analysis of the problem. (paper)

  20. Moments About Body Centered Coordinate Axes At Limb Joints From Force Plate And Biplane Photography Measurements

    Science.gov (United States)

    Balakrishnan, S.; Thornton-Trump, A. B.; Brodland, G. W.

    1983-07-01

    Traditional locomotion analysis considers motion in a translating coordinate frame and the analysis is performed primarily in the sagittal plane. The results of several studies in the present work have shown that the aspect of symmetry is rarely present in pathological gait. Loss of function in one plane of movement gives rise to larger motions in other planes. This brings into focus the necessity for three dimensional measurement for adequately representing pathological gait. Description of quantities associated with gait in the appropriate moving frame of each segment would be closer to joint angulation of limb segments. Although this description has been attempted by a few researchers, the assumption of small angle theory and vectorial addition of rotation angles commonly employed for defining the rotation matrices is not applicable to pathological gait. The present work illustrates the use of biplane photography for displacement measurement in human movement. Transformations based on Eulerian angle rotations are derived based on biplane measurements. From the three dimensional ground reaction forces measured by a force plate, moments about the moving upper body coordinate axes are computed through a three dimensional mathematical model.

  1. Uncertainty compensation methods for quantitative hardness measurement of materials using atomic force microscope nanoindentation technique

    International Nuclear Information System (INIS)

    We suggest uncertainty compensation methods for the quantification of nanoscale indentation using atomic force microscopy (AFM). The main error factors in the force–distance curves originated from the difference between theoretical and real shape of AFM tip during nanoscale indentation measurements. For the uncertainty compensations of tip shapes and misalignment of loading axis, we applied the enhanced tip geometry function and Y-scanner moving to the AFM measurements. Three different materials such as Si wafer, glass, and Au film were characterized with these compensation methods. By applying compensation methods, our results show the decreased values from 167% to 39% below 100 nm indenting depth compared with the literature values. These compensation methods applied to thin films will show the advanced quantitative analysis of hardness measurements using nanoscale indenting AFM. - Highlights: • We suggest uncertainty compensation methods for quantitative hardness measurement. • The main errors during indentation are tip geometry and non-uniform loading. • 3D tip characterization is obtained by using atomic force microscope scan. • The compensation methods perform well in thin films below thickness of 100 nm

  2. Influence of Halide Solutions on Collagen Networks: Measurements of Physical Properties by Atomic Force Microscopy

    Science.gov (United States)

    Kempe, André; Lackner, Maximilian

    2016-01-01

    The influence of aqueous halide solutions on collagen coatings was tested. The effects on resistance against indentation/penetration on adhesion forces were measured by atomic force microscopy (AFM) and the change of Young's modulus of the coating was derived. Comparative measurements over time were conducted with halide solutions of various concentrations. Physical properties of the mesh-like coating generally showed large variability. Starting with a compact set of physical properties, data disperse after minutes. A trend of increase in elasticity and permeability was found for all halide solutions. These changes were largest in NaI, displaying a logical trend with ion size. However a correlation with concentration was not measured. Adhesion properties were found to be independent of mechanical properties. The paper also presents practical experience for AFM measurements of soft tissue under liquids, particularly related to data evaluation. The weakening in physical strength found after exposure to halide solutions may be interpreted as widening of the network structure or change in the chemical properties in part of the collagen fibres (swelling). In order to design customized surface coatings at optimized conditions also for medical applications, halide solutions might be used as agents with little impact on the safety of patients.

  3. Bite Angle Effects in Hydroformylation Catalysis

    Institute of Scientific and Technical Information of China (English)

    van LEEUWEN

    2001-01-01

    Recent advances in rhodium catalyzed hydroformylation using xanthene-based ligands will be reviewed.The calculated natural bite angles of the ligands discussed are in the range 100-123℃ While the general trend is clear-higher 1:b ratios at wider angles, small changes in the bite angle do not exhibit a regular effect on the selectivity of the reaction.The same is true for the rate of CO dissociation;the larger the rate of the CO dissociation, the larger the rate of hydroformylation, but for small changes the effects do not comply with this rule.

  4. Cerebral infarction: an unusual manifestation of viper snake bite

    OpenAIRE

    Jyotirmoy Pal; Sumantro Mondal; Debanjali Sinha; Tony Ete; Atanu Chakraborty; Arijit Nag; Gouranga Sarkar; Bikram Saha

    2014-01-01

    Snake envenomation causes significant mortality and morbidity. Viper bite usually present with local cellulites, renal failure and bleeding disorders. Thrombotic manifestation of snake bite is rarely reported and early administration of Anti-Snake Venom Serum (ASV) also reduces the risk of thrombotic complications. Cerebral infarction in case of viper bite may be due to hypotension, hypercoagulability or direct action of venom on vessel wall. We report a rare case of viper bite, presented wit...

  5. Bacteremia with Bacteroides pyogenes after a cat bite

    DEFF Research Database (Denmark)

    Madsen, Ida Ringsborg; Justesen, Ulrik Stenz

    2011-01-01

    Animal bite wounds are often infected with bacteria from the animal's oral flora. We report what we believe to be the first case of bacteremia with Bacteroides pyogenes resulting from an infected cat bite.......Animal bite wounds are often infected with bacteria from the animal's oral flora. We report what we believe to be the first case of bacteremia with Bacteroides pyogenes resulting from an infected cat bite....

  6. The effect of lower anterior high pull headgear on treatment of moderate open bite in adults

    Directory of Open Access Journals (Sweden)

    Rahman Showkatbakhsh

    2012-01-01

    Full Text Available Background and Aims: Various methods are used for treatment of open bite. The objective of this study was to investigate the effects of Lower Anterior High Pull Headgear (LAHPH appliance in Class I subjects with moderate open bite and high lower lip line.Materials and Methods: The study group was composed of 10 subjects with a mean age of 15.8±2.5 years and 3.05 ± 0.07 mm moderate open bite. All the patients rejected orthognathic surgery. The treatment included extraction of upper and lower second premolars followed by leveling, banding, bonding, posterior space closure, and anterior retraction. After these procedures, the open bite was reduced to 2.04±1.17 mm. Afterwards, LAHPH was applied for 18 hours per day for 8±2 months. LAHPH appliance was composed of High Pull Headgear and two hooks mounted on its inner bow. Two elastics (1.8, light, Dentaurum connected the upper hooks on the inner bow to the lower hooks on the mandibular canines vertically. The forces produced by the prescribed elastics were 10 and 60 g during mouth closing and opening, respectively. Paired T-test was used to evaluate pre-andpost-treatment outcomes.Results: The pre-and post-treatment cephalometric evaluations showed that the LAHPH reduced effectively the open bite of the patients to 0.15±1.7 mm (P<0.001.Conclusion: This appliance can be used as an acceptable method for closing the open bite in Class I subjects.

  7. Proximity effect on hydrodynamic interaction between a sphere and a plane measured by Force Feedback Microscopy at different frequencies

    CERN Document Server

    Carpentier, Simon; Charlaix, Elisabeth; Chevrier, Joel

    2015-01-01

    In this article, we measure the viscous damping $G'',$ and the associated stiffness $G',$ of a liquid flow in sphere-plane geometry in a large frequency range. In this regime, the lubrication approximation is expected to dominate. We first measure the static force applied to the tip. This is made possible thanks to a force feedback method. Adding a sub-nanometer oscillation of the tip, we obtain the dynamic part of the interaction with solely the knowledge of the lever properties in the experimental context using a linear transformation of the amplitude and phase change. Using a Force Feedback Microscope (FFM)we are then able to measure simultaneously the static force, the stiffness and the dissipative part of the interaction in a broad frequency range using a single AFM probe. Similar measurements have been performed by the Surface Force Apparatus with a probe radius hundred times bigger. In this context the FFM can be called nano-SFA.

  8. Proximity effect on hydrodynamic interaction between a sphere and a plane measured by force feedback microscopy at different frequencies

    Science.gov (United States)

    Carpentier, Simon; Rodrigues, Mario S.; Charlaix, Elisabeth; Chevrier, Joël

    2015-07-01

    In this article, we measure the viscous damping G″, and the associated stiffness G', of a liquid flow in sphere-plane geometry over a large frequency range. In this regime, the lubrication approximation is expected to dominate. We first measure the static force applied to the tip. This is made possible thanks to a force feedback method. Adding a sub-nanometer oscillation of the tip, we obtain the dynamic part of the interaction with solely the knowledge of the lever properties in the experimental context using a linear transformation of the amplitude and phase change. Using a Force Feedback Microscope (FFM), we are then able to measure simultaneously the static force, the stiffness, and the dissipative part of the interaction in a broad frequency range using a single AFM probe. Similar measurements have been performed by the Surface Force Apparatus (SFA) with a probe radius hundred times bigger. In this context, the FFM can be called nano-SFA.

  9. Verification of joint input-state estimation for force identification by means of in situ measurements on a footbridge

    Science.gov (United States)

    Maes, K.; Nimmen, K. Van; Lourens, E.; Rezayat, A.; Guillaume, P.; Roeck, G. De; Lombaert, G.

    2016-06-01

    This paper presents a verification of a joint input-state estimation algorithm using data obtained from in situ experiments on a footbridge. The estimation of the input and the system states is performed in a minimum-variance unbiased way, based on a limited number of response measurements and a system model. A dynamic model of the footbridge is obtained using a detailed finite element model that is updated using a set of experimental modal characteristics. The joint input-state estimation algorithm is used for the identification of two impact, harmonic, and swept sine forces applied to the bridge deck. In addition to these forces, unknown stochastic forces, such as wind loads, are acting on the structure. These forces, as well as measurement errors, give rise to uncertainty in the estimated forces and system states. Quantification of the uncertainty requires determination of the power spectral density of the unknown stochastic excitation, which is identified from the structural response under ambient loading. The verification involves comparing the estimated forces with the actual, measured forces. Although a good overall agreement is obtained between the estimated and measured forces, modeling errors prohibit a proper distinction between multiple forces applied to the structure for the case of harmonic and swept sine excitation.

  10. Vine snake (Thelotornis capensis bite in a dog : clinical communication

    Directory of Open Access Journals (Sweden)

    J. Otto

    2003-06-01

    Full Text Available A vine snake bite in a dog is reported. There was continued minor bleeding from the assumed nose bite site for 4 days. Currently manufactured snakebite antivenom is not effective against vine snake bites and treatment is supportive.

  11. Using Risk Group Profiles as a Lightweight Qualitative Approach for Intervention Development: An Example of Prevention of Tick Bites and Lyme Disease

    NARCIS (Netherlands)

    Beaujean, Desirée; Velsen, van L.; Gemert-Pijnen, van J.E.; Maat, a; Steenbergen, van Jim; Crutzen, R

    2013-01-01

    Background: Many public health campaigns use a one-size-fits-all strategy to achieve their desired effect. Public health campaigns for tick bites and Lyme disease (LD) in many countries convey all relevant preventive measures to all members of the public. Although preventing tick bites (eg, by weari

  12. Application of magnetic resonance force microscopy cyclic adiabatic inversion for a single-spin measurement

    CERN Document Server

    Berman, G P; Chapline, G; Gurvitz, S A; Hammel, P C; Pelekhov, D V; Suter, A; Tsifrinovich, V I

    2003-01-01

    We consider the process of a single-spin measurement using magnetic resonance force microscopy (MRFM) with a cyclic adiabatic inversion (CAI). This technique is also important for different applications, including a measurement of a qubit state in quantum computation. The measurement takes place through the interaction of a single spin with a cantilever modelled by a quantum oscillator in a coherent state in a quasi-classical range of parameters. The entire system is treated rigorously within the framework of the Schroedinger equation. For a many-spin system our equations accurately describe conventional MRFM experiments involving CAI of the spin system. Our computer simulations of the quantum spin-cantilever dynamics show that the probability distribution for the cantilever position develops two asymmetric peaks with the total relative probabilities mainly dependent on the initial angle between the directions of the average spin and the effective magnetic field, in the rotating frame. We show that each of th...

  13. Repeatability of measurements: Non-Hermitian observables and quantum Coriolis force

    Science.gov (United States)

    Gardas, Bartłomiej; Deffner, Sebastian; Saxena, Avadh

    2016-08-01

    A noncommuting measurement transfers, via the apparatus, information encoded in a system's state to the external "observer." Classical measurements determine properties of physical objects. In the quantum realm, the very same notion restricts the recording process to orthogonal states as only those are distinguishable by measurements. Therefore, even a possibility to describe physical reality by means of non-Hermitian operators should volens nolens be excluded as their eigenstates are not orthogonal. Here, we show that non-Hermitian operators with real spectra can be treated within the standard framework of quantum mechanics. Furthermore, we propose a quantum canonical transformation that maps Hermitian systems onto non-Hermitian ones. Similar to classical inertial forces this map is accompanied by an energetic cost, pinning the system on the unitary path.

  14. Measurement of Elastic Properties of Tissue by Shear Wave Propagation Generated by Acoustic Radiation Force

    Science.gov (United States)

    Tabaru, Marie; Azuma, Takashi; Hashiba, Kunio

    2010-07-01

    Acoustic radiation force (ARF) imaging has been developed as a novel elastography technology to diagnose hepatic disease and breast cancer. The accuracy of shear wave speed estimation, which is one of the applications of ARF elastography, is studied. The Young's moduli of pig liver and foie gras samples estimated from the shear wave speed were compared with those measured the static Young's modulus measurement. The difference in the two methods was 8%. Distance attenuation characteristics of the shear wave were also studied using finite element method (FEM) analysis. We found that the differences in the axial and lateral beam widths in pressure and ARF are 16 and 9% at F-number=0.9. We studied the relationship between two branch points in distance attenuation characteristics and the shape of ARF. We found that the maximum measurable length to estimate shear wave speed for one ARF excitation was 8 mm.

  15. A review of measurement-based assessments of the aerosol direct radiative effect and forcing

    Directory of Open Access Journals (Sweden)

    H. Yu

    2006-01-01

    Full Text Available Aerosols affect the Earth's energy budget directly by scattering and absorbing radiation and indirectly by acting as cloud condensation nuclei and, thereby, affecting cloud properties. However, large uncertainties exist in current estimates of aerosol forcing because of incomplete knowledge concerning the distribution and the physical and chemical properties of aerosols as well as aerosol-cloud interactions. In recent years, a great deal of effort has gone into improving measurements and datasets. It is thus feasible to shift the estimates of aerosol forcing from largely model-based to increasingly measurement-based. Our goal is to assess current observational capabilities and identify uncertainties in the aerosol direct forcing through comparisons of different methods with independent sources of uncertainties. Here we assess the aerosol optical depth (τ, direct radiative effect (DRE by natural and anthropogenic aerosols, and direct climate forcing (DCF by anthropogenic aerosols, focusing on satellite and ground-based measurements supplemented by global chemical transport model (CTM simulations. The multi-spectral MODIS measures global distributions of aerosol optical depth (τ on a daily scale, with a high accuracy of ±0.03±0.05τ over ocean. The annual average τ is about 0.14 over global ocean, of which about 21%±7% is contributed by human activities, as estimated by MODIS fine-mode fraction. The multi-angle MISR derives an annual average AOD of 0.23 over global land with an uncertainty of ~20% or ±0.05. These high-accuracy aerosol products and broadband flux measurements from CERES make it feasible to obtain observational constraints for the aerosol direct effect, especially over global the ocean. A number of measurement-based approaches estimate the clear-sky DRE (on solar radiation at the top-of-atmosphere (TOA to be about -5.5±0.2 Wm-2 (median ± standard error from various methods over the global ocean. Accounting for thin cirrus

  16. A photoresponse-compensated parallel piezoresistive cantilever for cellular force measurements

    International Nuclear Information System (INIS)

    This paper describes a parallel piezoresistive cantilever that is composed of a force-sensing cantilever in addition to a reference cantilever for photoresponse compensation. Piezoresistive cantilevers have been applied in many cellular mechanical measurement studies because of their high sensitivity, high time resolution and ease of handling. However, the electrical resistance changes in response to the excitation light of the fluorescence microscope, which affects the cell measurements. We measured the I–V characteristics of a piezoresistive layer. These photoresponses occurred due to the internal photoelectric effect. We canceled the photoresponses using the reference cantilever. This paper demonstrates compensation of the cantilever photoresponse under irradiation at different angles, wavelengths and light intensities. As a result, the photoresponse could be decreased by 87%. (paper)

  17. Sonic booms produced by US Air Force and US Navy aircraft: Measured data

    Science.gov (United States)

    Lee, R. A.; Downing, J. M.

    1991-01-01

    A sonic measurement program was conducted at Edwards Air Force Base. Sonic boom signatures, produced by F-4, F-14, F-15, F-16, F-18, F-111, SR-71, and T-38 aircraft, were obtained under the flight track and at various lateral sites which were located up to 18 miles off-track. Thirteen monitors developed by Det 1 AL/BBE were used to collect full sonic boom waveforms, and nine modified dosimeters were used to collect supplemental peak overpressures and the C-weighted Sound Exposure Levels (CSEL) for 43 near steady supersonic flights of the above United States Air Force and United States Navy aircraft. This report describes the measured database (BOOMFILE) that contains sonic boom signatures and overpressures, aircraft tracking, and local weather data. These measured data highlight the major influences on sonic boom propagation and generation. The data from this study show that a constant offset of 26 from the peak overpressure expressed in dB gives a good estimate of the CSEL of a sonic boom.

  18. Frequency, amplitude, and phase measurements in contact resonance atomic force microscopies

    Directory of Open Access Journals (Sweden)

    Gheorghe Stan

    2014-03-01

    Full Text Available The resonance frequency, amplitude, and phase response of the first two eigenmodes of two contact-resonance atomic force microscopy (CR-AFM configurations, which differ in the method used to excite the system (cantilever base vs sample excitation, are analyzed in this work. Similarities and differences in the observables of the cantilever dynamics, as well as the different effect of the tip–sample contact properties on those observables in each configuration are discussed. Finally, the expected accuracy of CR-AFM using phase-locked loop detection is investigated and quantification of the typical errors incurred during measurements is provided.

  19. Inter-atomic force constants of BaF{sub 2} by diffuse neutron scattering measurement

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Takashi, E-mail: sakuma@mx.ibaraki.ac.jp; Makhsun,; Sakai, Ryutaro [Institute of Applied Beam Science, Ibaraki University, Mito 310-8512 (Japan); Xianglian [College of Physics and Electronics Information, Inner Mongolia University for the Nationalities, Tongliao 028043 (China); Takahashi, Haruyuki [Institute of Applied Beam Science, Ibaraki University, Hitachi 316-8511 (Japan); Basar, Khairul [Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132 (Indonesia); Igawa, Naoki [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Danilkin, Sergey A. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Kirrawee DC NSW 2232 (Australia)

    2015-04-16

    Diffuse neutron scattering measurement on BaF{sub 2} crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF{sub 2} was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. The force constants among neighboring atoms in BaF{sub 2} were determined and compared to those in ionic crystals and semiconductors.

  20. Work function of few layer graphene covered nickel thin films measured with Kelvin probe force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Eren, B. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Material Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Gysin, U.; Marot, L., E-mail: Laurent.marot@unibas.ch; Glatzel, Th.; Steiner, R.; Meyer, E. [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)

    2016-01-25

    Few layer graphene and graphite are simultaneously grown on a ∼100 nm thick polycrystalline nickel film. The work function of few layer graphene/Ni is found to be 4.15 eV with a variation of 50 meV by local measurements with Kelvin probe force microscopy. This value is lower than the work function of free standing graphene due to peculiar electronic structure resulting from metal 3d-carbon 2p(π) hybridization.