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Sample records for forceps tweezers hooks

  1. The history and evolution of surgical instruments. VII. Spring forceps (tweezers), hooks and simple retractors.

    PubMed Central

    Kirkup, J.

    1996-01-01

    Instruments manufactured by bending a basic metal strip or rod, either about its middle to create spring forceps (tweezers), or towards one extremity to create hooks and retractors are related structures. Spring forceps depend on tension mediated at the bend (hoop) or fixed end which is transmitted as dynamic 'spring' to the jaws, whereas the bend of hooks and retractors remains fixed and static. If such instruments refine the digital postures of pinch, pincer and retraction during surgery, they have not supplanted these manual actions entirely. After a brief historical introduction, the structure, modifications, functions and controls of spring forceps are analysed. Importantly, this instrument enjoys both right and left-handed functions, some of which are ancient, some transient as haemostats and needle-holders, and some, including left-handed dissection, surprisingly recent. Hooks are sharp or blunt and, among other functions, pre-date the left-handed spring forceps for dissection; in general hooks function as retractors. Hand-held retractors are enlarged blunt hooks, the wide retracting contact surface reducing trauma to wound margins and viscera. The physical effort of employing these retractors deep in body cavities is abated by applying them autostatically around a square or circular frame. Images Figure 1 PMID:8943642

  2. Forceps Delivery

    MedlinePlus

    ... provider might limit the amount of time you push. Your baby is facing the wrong direction. A forceps delivery might be needed if your baby is facing up (occiput posterior position) rather than down (occiput anterior ...

  3. Assisted delivery with forceps

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000509.htm Assisted delivery with forceps To use the sharing features on ... called vacuum assisted delivery . When is a Forceps Delivery Needed? Even after your cervix is fully dilated ( ...

  4. Optical Tweezer Assembly and Calibration

    NASA Technical Reports Server (NTRS)

    Collins, Timothy M.

    2004-01-01

    An Optical Tweezer, as the name implies, is a useful tool for precision manipulation of micro and nano scale objects. Using the principle of electromagnetic radiation pressure, an optical tweezer employs a tightly focused laser beam to trap and position objects of various shapes and sizes. These devices can trap micrometer and nanometer sized objects. An exciting possibility for optical tweezers is its future potential to manipulate and assemble micro and nano sized sensors. A typical optical tweezer makes use of the following components: laser, mirrors, lenses, a high quality microscope, stage, Charge Coupled Device (CCD) camera, TV monitor and Position Sensitive Detectors (PSDs). The laser wavelength employed is typically in the visible or infrared spectrum. The laser beam is directed via mirrors and lenses into the microscope. It is then tightly focused by a high magnification, high numerical aperture microscope objective into the sample slide, which is mounted on a translating stage. The sample slide contains a sealed, small volume of fluid that the objects are suspended in. The most common objects trapped by optical tweezers are dielectric spheres. When trapped, a sphere will literally snap into and center itself in the laser beam. The PSD s are mounted in such a way to receive the backscatter after the beam has passed through the trap. PSD s used with the Differential Interference Contrast (DIC) technique provide highly precise data. Most optical tweezers employ lasers with power levels ranging from 10 to 100 miliwatts. Typical forces exerted on trapped objects are in the pico-newton range. When PSDs are employed, object movement can be resolved on a nanometer scale in a time range of milliseconds. Such accuracy, however, can only by utilized by calibrating the optical tweezer. Fortunately, an optical tweezer can be modeled accurately as a simple spring. This allows Hook s Law to be used. My goal this summer at NASA Glenn Research Center is the assembly and

  5. [Parametrial hematoma after forceps delivery].

    PubMed

    Winkler, M; Gans, A; Fendel, H

    1991-01-01

    We report on a large intraligamentous haematoma developed after low forceps delivery. The diagnosis was made from symptoms and signs, rectal examination, and sonographic findings. The haematoma was incised and clots were evacuated by laparotomy. The bleeding vessel could be ligated. The 31-year-old woman left our hospital on the 12th postoperative day.

  6. Composite redesign of obstetrical forceps

    NASA Technical Reports Server (NTRS)

    Lawson, Seth W.; Smeltzer, Stan S.

    1994-01-01

    Due to the increase in the number of children being born recently, medical technology has struggled to keep pace in certain areas. In these areas, particular needs have arisen to which the subject of this paper is directed. In the area of obstetrics, the forceps design and function has remained relatively unchanged for a number of years. In an effort to advance the technology, NASA Marshall Space Flight Center has been asked by the obstetrical community to help in a redesign of the obstetric forceps. Traditionally the forceps design has been of tubular stainless steel, constructed in two halves which interlock and hinge to provide the gripping force necessary to aid in the delivery of an infant. The stainless steel material was used to provide for ease of cleaning and sterilization. However, one of the drawbacks of the non-flexible steel design is that excessive force can be placed upon an infants head which could result in damage or injury to the infant. The redesign of this particular obstetric tool involves applying NASA's knowledge of advanced materials and state of the art instrumentation to create a tool which can be used freely throughout the obstetrics community without the fear of injury to an infant being delivered.

  7. 21 CFR 868.5780 - Tube introduction forceps.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tube introduction forceps. 868.5780 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5780 Tube introduction forceps. (a) Identification. Tube introduction forceps (e.g., Magill forceps) are a right-angled device used to grasp...

  8. 21 CFR 868.5780 - Tube introduction forceps.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Tube introduction forceps. 868.5780 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5780 Tube introduction forceps. (a) Identification. Tube introduction forceps (e.g., Magill forceps) are a right-angled device used to grasp...

  9. 21 CFR 868.5780 - Tube introduction forceps.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Tube introduction forceps. 868.5780 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5780 Tube introduction forceps. (a) Identification. Tube introduction forceps (e.g., Magill forceps) are a right-angled device used to grasp...

  10. 21 CFR 868.5780 - Tube introduction forceps.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Tube introduction forceps. 868.5780 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5780 Tube introduction forceps. (a) Identification. Tube introduction forceps (e.g., Magill forceps) are a right-angled device used to grasp...

  11. 21 CFR 868.5780 - Tube introduction forceps.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Tube introduction forceps. 868.5780 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5780 Tube introduction forceps. (a) Identification. Tube introduction forceps (e.g., Magill forceps) are a right-angled device used to grasp...

  12. Femtosecond Optical Tweezers

    NASA Astrophysics Data System (ADS)

    Peng, Jiahui; Wang, Lei; Sokolov, Alexei

    2004-10-01

    Optical tweezers has drawn much attention of people since recent years, which shows great advantages on biological applications due to quite straightforward ideas and simple configurations. Optical tweezers rely upon the extremely high gradient in the electric field produced near the beam waist of a tightly focused laser beam, which creates a force sufficient to trap micron-sized dielectric particles in three dimensions.(J.E. Molloy and M.J. Padgett, Light, Action: Optical Tweezers, Contemporary P)hysics, 43 241 (2002). We applied a femtosecond laser on optical tweezers as light source and got successfully ``optical trapping'' and ``optical tweezers.'' Further, due to the characters of short pulse width and extremely high intensity of laser, femtosecond optical tweezers may direct us to new optics field. Under such strong intensity many non-linear optical phenomena could be observable, such like optical Kerr effect, stimulated Raman effect and so on. Our work will shows that it may be applied into the recently proposed FAST CAR (Femtosecond Adaptive Spectroscopic Techniques for Coherent Anti-Stokes Raman Spectroscopy) by M. Scully et. al.(M. O. Scully, G. W. Kattawar, R. P. Lucht, T. Opatrny, H. Pilloff, A. Rebane, A. V. Sokolov, and M. S. Zubairy, ``FAST CARS: Engineering a Laser Spectroscopic Technique for Rapid Identification of Bacterial Spores,'' Proceedings of NASE (2002).)

  13. Automation of optical tweezers

    NASA Astrophysics Data System (ADS)

    Hsieh, Tseng-Ming; Chang, Bo-Jui; Hsu, Long

    2000-07-01

    Optical tweezers is a newly developed instrument, which makes possible the manipulation of micro-optical particles under a microscope. In this paper, we present the automation of an optical tweezers which consists of a modified optical tweezers, equipped with two motorized actuators to deflect a 1 W argon laser beam, and a computer control system including a joystick. The trapping of a single bead and a group of lactoacidofilus was shown, separately. With the aid of the joystick and two auxiliary cursers superimposed on the real-time image of a trapped bead, we demonstrated the simple and convenient operation of the automated optical tweezers. By steering the joystick and then pressing a button on it, we assign a new location for the trapped bead to move to. The increment of the motion 0.04 (mu) m for a 20X objective, is negligible. With a fast computer for image processing, the manipulation of the trapped bead is smooth and accurate. The automation of the optical tweezers is also programmable. This technique may be applied to accelerate the DNA hybridization in a gene chip. The combination of the modified optical tweezers with the computer control system provides a tool for precise manipulation of micro particles in many scientific fields.

  14. Video-optic cable endoscopy forceps.

    PubMed

    Weiss, Markus; Holzmann, David; Gerber, Andreas Ch

    2003-03-01

    We present a video-endoscopic technology for foreign body extractions with forceps. This can easily be followed and is recordable on video monitor in excellent quality. Instead of a rigid rod lens telescope, a fiberoptic video endoscope is inserted into the optical channel of a bronchoscopic forceps. This keeps the endoscopic device lightweight and easily maneuverable in different angles. The principle can be applied to other rigid diagnostic and therapeutic endoscopic equipment and represents a potential alternative technology to the use of cameras attached to rigid telescopes.

  15. Lunar crane hook

    NASA Technical Reports Server (NTRS)

    Cash, John Wilson, III; Cone, Alan E.; Garolera, Frank J.; German, David; Lindabury, David Peter; Luckado, Marshall Cleveland; Murphey, Craig; Rowell, John Bryan; Wilkinson, Brad

    1988-01-01

    The base and ball hook system is an attachment that is designed to be used on the lunar surface as an improved alternative to the common crane hook and eye system. The design proposed uses an omni-directional ball hook and base to overcome the design problems associated with a conventional crane hook. The base and ball hook is not sensitive to cable twist which would render a robotic lunar crane useless since there is little atmospheric resistance to dampen the motion of an oscillating member. The symmetric characteristics of the ball hook and base eliminates manual placement of the ball hook into the base; commonly associated with the typical hook and eye stem. The major advantage of the base and ball hook system is it's ease of couple and uncouple modes that are advantages during unmanned robotic lunar missions.

  16. Split-mouth comparison of physics forceps and extraction forceps in orthodontic extraction of upper premolars.

    PubMed

    Hariharan, Samyuktha; Narayanan, Vinod; Soh, Chen Loong

    2014-12-01

    We compared outcome variables (operative complications, inflammatory complications, and operating time) in patients being treated by orthodontic extraction of upper premolars with the Physics forceps or the universal extraction forceps. We organised a single blind, split-mouth clinical trial to compare the outcomes of the 2 groups (n=54 premolars). The Physics forceps group had lower mean (SD) visual analogue scores (VAS) for pain (0.59 (0.57)) on the first postoperative day than the other group (1.04 (0.85)) (p=0.03). There were no other significant differences between the 2 groups in any other variable studied.

  17. Obstetrical Forceps Would Limit Force On An Infant's Head

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stan; Lawson, Seth

    1995-01-01

    Improved obstetrical forceps proposed to reduce injuries to newborn infants. Fabricated mostly of thermoplastic material. Reinforcing fibers added in hinge region of forceps. Combination of material, size, and shape chosen to make forceps yield elastically by amount keeping applied force from rising beyond maximum allowable value. Fiber-optic sensors for measuring strains embedded in forceps. Strain measurements used to compute tensile and compressive forces applied to infant's head.

  18. Combined forceps and catheter extraction of an oesophageal foreign body.

    PubMed

    al-Shahi, R; O'Connell, M; Huchzermeyer, P; Moore-Gillon, V

    1997-06-01

    The extraction of impacted foreign bodies from the oesophagus is frequently performed using forceps under endoscopic guidance. We report the case of a 23-year-old prisoner who ingested a lump of cannabis resin which could not be removed from the upper oesophagus with forceps alone. We recommend the use of a Fogarty balloon catheter in conjunction with toothed forceps in such cases.

  19. 21 CFR 884.4400 - Obstetric forceps.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Obstetric forceps. 884.4400 Section 884.4400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... delivery. (b) Classification. Class II (performance standards)....

  20. Design of a new instrumented forceps: application to safe obstetrical forceps blade placement.

    PubMed

    Moreau, Richard; Pham, Minh Tu; Silveira, Ruimark; Redarce, Tanneguy; Brun, Xavier; Dupuis, Olivier

    2007-07-01

    Today, medical simulators are increasingly gaining appeal in clinical settings. In obstetrics childbirth simulators provide a training and research tool for comparing various techniques that use obstetrical instruments or validating new methods. Especially in the case of difficult deliveries, the use of obstetrical instruments-such as forceps, spatulas, and vacuum extractors-has become essential. However, such instruments increase the risk of injury to both the mother and fetus. Only clinical experience acquired in the delivery room enables health professionals to reduce this risk. In this context, we have developed, in collaboration with researchers and physicians, a new type of instrumented forceps that offers new solutions for training obstetricians in the safe performance of forceps deliveries. This paper focuses on the design of this instrumented forceps, coupled with the BirthSIM simulator. This instrumented forceps allows to study its displacement inside the maternal pelvis. Methods for analyzing the operator repeatability and to compare forceps blade placements to a reference one are developed. The results highlight the need of teaching tools to adequately train novice obstetricians.

  1. Getting Hooked on Physics!

    ERIC Educational Resources Information Center

    McHugh, M.; McCauley, V.

    2016-01-01

    A number of papers in this journal have dealt with the idea of using hooks in physics instruction. A hook, as the name suggests, engages students in learning by triggering their attention and interest. Hooks can be any type of pedagogical approach--a question, a demonstration, a puzzle or video. They are generally short and center on the most…

  2. Interferometer Control of Optical Tweezers

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2002-01-01

    This paper discusses progress in using spatial light modulators and interferometry to control the beam profile of an optical tweezers. The approach being developed is to use a spatial light modulator (SLM) to control the phase profile of the tweezers beam and to use a combination of the SLM and interferometry to control the intensity profile. The objective is to perform fine and calculable control of the moments and forces on a tip or tool to be used to manipulate and interrogate nanostructures. The performance of the SLM in generating multiple and independently controllable tweezers beams is also reported. Concurrent supporting research projects are mentioned and include tweezers beam scattering and neural-net processing of the interference patterns for control of the tweezers beams.

  3. CP-OCT sensor guided SMART micro-forceps

    NASA Astrophysics Data System (ADS)

    Song, Cheol; Gehlbach, Peter L.; Kang, Jin U.

    2014-02-01

    Even the most stable hands have unintended movements on the order of 50-100 microns within 0-15 Hz. Micro-forceps are one of the frequently used microsurgical tools used to grasp thin layers of tissue during microsurgery. Here, a handheld Smart Micromanipulation Aided Robotic-surgery Tool (SMART) micro-forceps is developed by integrating a fiber-optic common-path optical coherence tomography (CP-OCT) sensor into the micro-forceps. This forceps design could significantly improve performance by canceling unwanted hand tremor during the moment of a grasping. The basic grasping and peeling functions of the micro-forceps are evaluated in dry phantoms and in a biological tissue model.

  4. Are electron tweezers possible?

    PubMed

    Oleshko, Vladimir P; Howe, James M

    2011-11-01

    Positively answering the question in the title, we demonstrate in this work single electron beam trapping and steering of 20-300nm solid Al nanoparticles generated inside opaque submicron-sized molten Al-Si eutectic alloy spheres. Imaging of solid nanoparticles and liquid alloy in real time was performed using energy filtering in an analytical transmission electron microscope (TEM). Energy-filtering TEM combined with valence electron energy-loss spectroscopy enabled us to investigate in situ nanoscale transformations of the internal structure, temperature dependence of plasmon losses, and local electronic and optical properties under melting and crystallization of individual binary alloy particles. For particles below 20nm in size, enhanced vibrations of the dynamic solid-liquid interface due to instabilities near the critical threshold were observed just before melting. The obtained results indicate that focused electron beams can act as a tool for manipulation of metal nanoparticles by transferring linear and angular mechanical momenta. Such thermally assisted electron tweezers can be utilized for touchless manipulation and processing of individual nano-objects and potentially for fabrication of assembled nanodevices with atomic level sensitivity and lateral resolution provided by modern electron optical systems. This is by three orders of magnitude better than for light microscopy utilized in conventional optical tweezers. New research directions and potential applications of trapping and tracking of nano-objects by focused electron beams are outlined.

  5. Comparative Evaluation of Efficacy of Physics Forceps versus Conventional Forceps in Orthodontic Extractions: A Prospective Randomized Split Mouth Study

    PubMed Central

    Managutti, Anil M; Menat, Shailesh; Agarwal, Arvind; Shah, Dishan; Patel, Jigar

    2016-01-01

    Introduction Tooth extraction is one of the most commonly performed procedures in dentistry. It is usually a traumatic procedure often resulting in immediate destruction and loss of alveolar bone and surrounding soft tissues. Various instruments have been described to perform atraumatic extractions which can prevent damage to the paradental structures. Recently developed physics forceps is one of the instruments which is claimed to perform atraumatic extractions. Aim The aim of the present study was to compare the efficacy of physics forceps with conventional forceps in terms of operating time, prevention of marginal bone loss & soft tissue loss, postoperative pain and postoperative complications following bilateral premolar extractions for orthodontic purpose. Materials and Methods In this prospective split-mouth study, outcomes of the 2 groups (n = 42 premolars) requiring extraction of premolars for orthodontic treatment purpose using Physics forceps and Conventional forceps were compared. Clinical outcomes in form of time taken, loss of buccal soft tissue and buccal cortical plate based on extraction defect classification system, postoperative pain and other complication associated with extraction were recorded and compared. Results Statistically significant reduction in the operating time was noted in physics forceps group. Marginal bone loss and soft tissue loss was also significantly lesser in physics forceps group when compared to conventional forceps group. However, there was no statistically significant difference in severity of postoperative pain between both groups. Conclusion The results of the present study suggest that physics forceps was more efficient in reducing operating time and prevention of marginal bone loss & soft tissue loss when compared to conventional forceps in orthodontically indicated premolar extractions. PMID:27630951

  6. Optical tweezers on biaxial crystal

    NASA Astrophysics Data System (ADS)

    Angelsky, Oleg V.; Maksimyak, Andrew P.; Maksimyak, Peter P.

    2009-10-01

    In this paper, we propose optical tweezers based on a biaxial crystal. To control the movement of opaque particles, we use the shift polarization interferometer. The results of experimental study of laser tweezers are shown. We demonstrates movement of a microparticle of toner using singular-optical trap, rotate a particle due to orbital momentum, conversion of two traps when changing the plane of polarizer transmission and converging of two traps.

  7. Force Feedback Control of Robotic Forceps for Minimally Invasive Surgery

    NASA Astrophysics Data System (ADS)

    Ishii, Chiharu; Kamei, Yusuke

    2008-06-01

    Recently, the robotic surgical support systems are in clinical use for minimally invasive surgery. For improvement in operativity and safety of minimally invasive surgery, the development of haptic forceps manipulator is in demand to help surgeon's immersion and dexterity. We have developed a multi-DOF robotic forceps manipulator using a novel omni-directional bending mechanism, so far. In this paper, in order to control the developed robotic forceps as a slave manipulator, joy-stick type master manipulator with force feedback mechanism for remote control is designed and built, and force feedback bilateral control system was constructed for grasping and bending motions of the robotic forceps. Experimental works were carried out and experimental results showed the effectiveness of the proposed control system.

  8. Getting Hooked on Physics!

    NASA Astrophysics Data System (ADS)

    McHugh, M.; McCauley, V.

    2016-12-01

    A number of papers in this journal have dealt with the idea of using hooks in physics instruction. A hook, as the name suggests, engages students in learning by triggering their attention and interest. Hooks can be any type of pedagogical approach—a question, a demonstration, a puzzle or video. They are generally short and center on the most interesting aspects of a topic. Here we focus on using Conceptual Change (CC) teacher-led demonstrations as the pedagogical hook approach. Conceptual Change is an instructional method mentioned by a number of authors to stimulate interest among learners. This is where an educator presents an issue or topic that has associated misconceptions. As the teacher explains the truth behind the concept, cognitive conflict occurs and the students' initial perceptions are challenged and ideas start to change. However, the instruction used in association with the demonstrations must provide intelligible, plausible, relevant explanations so that students are convinced by the new ideas. The gap between prior knowledge and new knowledge has the potential to provide a strong stimulus for augmenting interest, engagement, and attention among students. Thus, CC can act as a hook in itself.

  9. Naegele Forceps Delivery and Association between Morbidity and the Number of Forceps Traction Applications: A Retrospective Study

    PubMed Central

    Matsumoto, Naoki; Takenaka, Toshifumi; Ikeda, Nobuyuki; Yazaki, Satoshi; Sato, Yuichi

    2015-01-01

    Objective. To present the method of Naegele forceps delivery clinically practiced by the lead author, its success rate, and morbidity and to evaluate the relationship between morbidity and the number of forceps traction applications. Methods. Naegele forceps delivery was performed when the fetal head reached station +2 cm, the forceps were applied in the maternal pelvic application, and traction was slowly and gently performed. In the past two years, Naegele forceps delivery was attempted by the lead author in 87 cases, which were retrospectively reviewed. Results. The numbers of traction applications were one in 64.7% of cases, two in 24.7%, and three or more in 10.7%. The success rate was 100%. No severe morbidity was observed in mothers or neonates. Neonatal facial injury occurred most commonly in cases with fetal head malrotation, elevated numbers of traction applications, and maternal complications. Umbilical artery acidemia most commonly occurred in cases with nonreassuring fetal status. The significant crude odds ratio for three or more traction applications was 20 in cases with malrotation. Conclusion. Naegele forceps delivery has a high success rate, but multiple traction applications will sometimes be required, particularly in cases with malrotation. Malrotation and elevated numbers of traction applications may lead to neonatal head damage. PMID:26425369

  10. Undergraduate Construction of Optical Tweezers

    NASA Astrophysics Data System (ADS)

    Hubbell, Lawrence

    2012-10-01

    I will present a poster on the construction of optical tweezers. This will demonstrate the full process one must go through when working on a research project. First I sifted through the internet for papers and information pertaining to the tweezers. Afterwards I discussed the budget with the lab manager. Next I made purchases, however some items, such as the sample mount, needed to be custom made. These I built in the machine shop. Once the tweezers were operational I spent some time ensuring that the mirrors and lenses were adjusted just right, so that the trap performed at full strength. Finally, I used video data of the Brownian motion of trapped silica microspheres to get a reasonable estimate of the trapping stiffness with such particles. As a general note, all of this was done with the intent of leaving the tweezers for future use by other undergraduates. Because of this extra effort was taken to ensure the tweezers were as safe to use as possible. For this reason a visible LASER was chosen over an infrared LASER, in addition, the LASER was oriented parallel to the surface of the table in order to avoid stray upwards beams.

  11. Reflections on Sandy Hook

    ERIC Educational Resources Information Center

    Trump, Kenneth S.

    2013-01-01

    In this article, the author shares his thoughts for district administrators regarding the Sandy Hook Elementary school tragedy. Administrators heard a lot of potential solutions or attempts at solutions. However, these proposals raise lengthy lists of implementation questions and issues that illustrate a lack of understanding of school operations,…

  12. Plasmon nano-optical tweezers

    NASA Astrophysics Data System (ADS)

    Juan, Mathieu L.; Righini, Maurizio; Quidant, Romain

    2011-06-01

    Conventional optical tweezers, formed at the diffraction-limited focus of a laser beam, have become a powerful and flexible tool for manipulating micrometre-sized objects. Extending optical trapping down to the nanometre scale would open unprecedented opportunities in many fields of science, where such nano-optical tweezers would allow the ultra-accurate positioning of single nano-objects. Among the possible strategies, the ability of metallic nanostructures to control light at the subwavelength scale can be exploited to engineer such nano-optical traps. This Review summarizes the recent advances in the emerging field of plasmon-based optical trapping and discusses the details of plasmon tweezers along with their potential applications to bioscience and quantum optics.

  13. Optical tweezers: 20 years on.

    PubMed

    McGloin, David

    2006-12-15

    In 1986, Arthur Ashkin and colleagues published a seminal paper in Optics Letters, 'Observation of a single-beam gradient force optical trap for dielectric particles' which outlined a technique for trapping micrometre-sized dielectric particles using a focused laser beam, a technology which is now termed optical tweezers. This paper will provide a background in optical manipulation technologies and an overview of the applications of optical tweezers. It contains some recent work on the optical manipulation of aerosols and concludes with a critical discussion of where the future might lead this maturing technology.

  14. Successful endoscopic fragmentation of large hardened fecaloma using jumbo forceps

    PubMed Central

    Matsuo, Yasumasa; Yasuda, Hiroshi; Nakano, Hiroyasu; Hattori, Miki; Ozawa, Midori; Sato, Yoshinori; Ikeda, Yoshiko; Ozawa, Shun-Ichiro; Yamashita, Masaki; Yamamoto, Hiroyuki; Itoh, Fumio

    2017-01-01

    We present a rare case of fecaloma, 7 cm in size, in the setting of systemic scleroderma. A colonoscopy revealed a giant brown fecaloma occupying the lumen of the colon and a colonic ulcer that was caused by the fecaloma. The surface of the fecaloma was hard, large and slippery, and fragmentation was not possible despite the use of various devices, including standard biopsy forceps, an injection needle, and a snare. However, jumbo forceps were able to shave the surface of the fecaloma and break it successfully by repeated biting for 6 h over 2 d. The ability of the jumbo forceps to collect large mucosal samples was also appropriate for achieving fragmentation of the giant fecaloma. PMID:28250902

  15. Successful endoscopic fragmentation of large hardened fecaloma using jumbo forceps.

    PubMed

    Matsuo, Yasumasa; Yasuda, Hiroshi; Nakano, Hiroyasu; Hattori, Miki; Ozawa, Midori; Sato, Yoshinori; Ikeda, Yoshiko; Ozawa, Shun-Ichiro; Yamashita, Masaki; Yamamoto, Hiroyuki; Itoh, Fumio

    2017-02-16

    We present a rare case of fecaloma, 7 cm in size, in the setting of systemic scleroderma. A colonoscopy revealed a giant brown fecaloma occupying the lumen of the colon and a colonic ulcer that was caused by the fecaloma. The surface of the fecaloma was hard, large and slippery, and fragmentation was not possible despite the use of various devices, including standard biopsy forceps, an injection needle, and a snare. However, jumbo forceps were able to shave the surface of the fecaloma and break it successfully by repeated biting for 6 h over 2 d. The ability of the jumbo forceps to collect large mucosal samples was also appropriate for achieving fragmentation of the giant fecaloma.

  16. Optical tweezers for confocal microscopy

    NASA Astrophysics Data System (ADS)

    Hoffmann, A.; Meyer zu Hörste, G.; Pilarczyk, G.; Monajembashi, S.; Uhl, V.; Greulich, K. O.

    2000-11-01

    In confocal laser scanning microscopes (CLSMs), lasers can be used for image formation as well as tools for the manipulation of microscopic objects. In the latter case, in addition to the imaging lasers, the light of an extra laser has to be focused into the object plane of the CLSM, for example as optical tweezers. Imaging as well as trapping by optical tweezers can be done using the same objective lens. In this case, z-sectioning for 3D imaging shifts the optical tweezers with the focal plane of the objective along the optical axis, so that a trapped object remains positioned in the focal plane. Consequently, 3D imaging of trapped objects is impossible without further measures. We present an experimental set-up keeping the axial trapping position of the optical tweezers at its intended position whilst the focal plane can be axially shifted over a distance of about 15 μm. It is based on fast-moving correctional optics synchronized with the objective movement. First examples of application are the 3D imaging of chloroplasts of Elodea densa (Canadian waterweed) in a vigorous cytoplasmic streaming and the displacement of zymogen granules in pancreatic cancer cells (AR42 J).

  17. Hooke's figurations: a figural drawing attributed to Robert Hooke.

    PubMed

    Hunter, Matthew C

    2010-09-20

    The experimental philosopher Robert Hooke (1635-1703) is known to have apprenticed to the leading painter Peter Lely on his first arrival in London in the late 1640s. Yet the relevance of Hooke's artistic training to his mature draughtsmanship and identity has remained unclear. Shedding light on that larger interpretive problem, this article argues for the attribution to Hooke of a figural drawing now in Tate Britain (T10678). This attributed drawing is especially interesting because it depicts human subjects and bears Hooke's name functioning as an artistic signature, both highly unusual features for his draughtsmanship. From evidence of how this drawing was collected and physically placed alongside images by leading artists in the early eighteenth century, I suggest how it can offer new insight into the reception of Hooke and his graphic work in the early Enlightenment.

  18. Force Sensing Micro-Forceps for Robot Assisted Retinal Surgery

    PubMed Central

    Kuru, İsmail; Gonenc, Berk; Balicki, Marcin; Handa, James; Gehlbach, Peter; Taylor, Russell H.; Iordachita, Iulian

    2014-01-01

    Membrane peeling is a standard vitreoretinal procedure, where the surgeon delaminates a very thin membrane from retina surface using surgical picks and forceps. This requires extremely delicate manipulation of the retinal tissue. Applying excessive forces during the surgery can cause serious complications leading to vision loss. For successful membrane peeling, most of the applied forces need to be very small, well below the human tactile sensation threshold. In this paper, we present a robotic system that combines a force sensing forceps tool and a cooperatively-controlled surgical robot. This combination allows us to measure the forces directly at the tool tip and use this information for limiting the applied forces on the retina. This may prevent many iatrogenic injuries and allow safer maneuvers during vitreoretinal procedures. We show that our system can successfully eliminate hand-tremor and excessive forces in membrane peeling experiments on the inner shell membrane of a chicken embryo. PMID:23366162

  19. Absolute calibration of optical tweezers

    SciTech Connect

    Viana, N.B.; Mazolli, A.; Maia Neto, P.A.; Nussenzveig, H.M.; Rocha, M.S.; Mesquita, O.N.

    2006-03-27

    As a step toward absolute calibration of optical tweezers, a first-principles theory of trapping forces with no adjustable parameters, corrected for spherical aberration, is experimentally tested. Employing two very different setups, we find generally very good agreement for the transverse trap stiffness as a function of microsphere radius for a broad range of radii, including the values employed in practice, and at different sample chamber depths. The domain of validity of the WKB ('geometrical optics') approximation to the theory is verified. Theoretical predictions for the trapping threshold, peak position, depth variation, multiple equilibria, and 'jump' effects are also confirmed.

  20. Optoelectronic tweezers for medical diagnostics

    NASA Astrophysics Data System (ADS)

    Kremer, Clemens; Neale, Steven; Menachery, Anoop; Barrett, Mike; Cooper, Jonathan M.

    2012-01-01

    Optoelectronic tweezers (OET) allows the spatial patterning of electric fields through selected illumination of a photoconductive surface. This enables the manipulation of micro particles and cells by creating non-uniform electrical fields that then produce dielectrophoretic (DEP) forces. The DEP responses of cells differ and can produce negative or positive (repelled or attracted to areas of high electric field) forces. Therefore OET can be used to manipulate individual cells and separate different cell types from each other. Thus OET has many applications for medical diagnostics, demonstrated here with work towards diagnosing Human African Trypanosomiasis, also known as sleeping sickness.

  1. Microcrystal manipulation with laser tweezers

    SciTech Connect

    Wagner, Armin Duman, Ramona; Stevens, Bob; Ward, Andy

    2013-07-01

    Optical trapping has successfully been applied to select and mount microcrystals for subsequent X-ray diffraction experiments. X-ray crystallography is the method of choice to deduce atomic resolution structural information from macromolecules. In recent years, significant investments in structural genomics initiatives have been undertaken to automate all steps in X-ray crystallography from protein expression to structure solution. Robotic systems are widely used to prepare crystallization screens and change samples on synchrotron beamlines for macromolecular crystallography. The only remaining manual handling step is the transfer of the crystal from the mother liquor onto the crystal holder. Manual mounting is relatively straightforward for crystals with dimensions of >25 µm; however, this step is nontrivial for smaller crystals. The mounting of microcrystals is becoming increasingly important as advances in microfocus synchrotron beamlines now allow data collection from crystals with dimensions of only a few micrometres. To make optimal usage of these beamlines, new approaches have to be taken to facilitate and automate this last manual handling step. Optical tweezers, which are routinely used for the manipulation of micrometre-sized objects, have successfully been applied to sort and mount macromolecular crystals on newly designed crystal holders. Diffraction data from CPV type 1 polyhedrin microcrystals mounted with laser tweezers are presented.

  2. Molecular clips and tweezers hosting neutral guests.

    PubMed

    Hardouin-Lerouge, Marie; Hudhomme, Piétrick; Sallé, Marc

    2011-01-01

    Intense current interest in supramolecular chemistry is devoted to the construction of molecular assemblies displaying controlled molecular motion associated to recognition. On this ground, molecular clips and tweezers have focused an increasing attention. This tutorial review points out the recent advances in the construction of always more sophisticated molecular clips and tweezers, illustrating their remarkably broad structural variety and focusing on their binding ability towards neutral guests. A particular attention is brought to recent findings in dynamic molecular tweezers whose recognition ability can be regulated by external stimuli. Porphyrin-based systems will not be covered here as this very active field has been recently reviewed.

  3. Quantum limited particle sensing in optical tweezers

    SciTech Connect

    Tay, J.W.; Hsu, Magnus T. L.; Bowen, Warwick P.

    2009-12-15

    Particle sensing in optical tweezers systems provides information on the position, velocity, and force of the specimen particles. The conventional quadrant detection scheme is applied ubiquitously in optical tweezers experiments to quantify these parameters. In this paper, we show that quadrant detection is nonoptimal for particle sensing in optical tweezers and propose an alternative optimal particle sensing scheme based on spatial homodyne detection. A formalism for particle sensing in terms of transverse spatial modes is developed and numerical simulations of the efficacies of both quadrant and spatial homodyne detection are shown. We demonstrate that 1 order of magnitude improvement in particle sensing sensitivity can be achieved using spatial homodyne over quadrant detection.

  4. Bacteriological Evaluation of Antiseptic Solutions Used to Keep Cheattle's Forceps.

    PubMed

    Agarwal, Pawan; Singh, Mahendra; Sharma, D

    2015-12-01

    There is little information available on the bacteriological contamination of Cheattle's forceps during routine use and the effects of antiseptic solutions. This study was conducted to detect infection in various antiseptics and disinfections in-use used for keeping the Cheattle's forceps in surgical wards. An aqueous solution of 0.5 and 1 % cetrimide/chlorhexidine, 2.4 % glutaraldehyde, 5 % povidone iodine, and 10 % chloroxylenol were compared using the normal saline as control. The samples from each bottle were sent for culture on the 3rd, 5th, and 7th day. All the culture reports were analyzed and statistically compared. A total of 2,160 samples were sent for culture from solutions including control over a period of 7 days. A total of 360 samples were sent for culture from each antiseptic solution. Out of 2,160 samples, 240 (11.11 %) were positive over a period of 7 days for contamination with microbial organisms. The most common organism isolated was Pseudomonas present in 140 samples followed by E. coli in 71 samples. S. aureus was present in seven samples, bacillus in ten samples, and Coaglase -ve Streptococcus and Klebsiella in six samples each. Number of positive culture consistently increased in normal saline and cetrimide/chlorhexidine, but povidone iodine, chloroxylenol, and glutaraldehyde did not show any positive culture on the 3rd day. Povidone iodine and glutaraldehyde showed positive culture on the 5th and 7th day, respectively., but they were statistically insignificant. On the 7th day, glutaraldehyde was the only solution which did not show any positive culture. We strongly recommend that the Cheattle's forceps should be kept in a bottle containing glutaraldehyde or chloroxylenol.

  5. Steerable optical tweezers for ultracold atom studies.

    PubMed

    Roberts, K O; McKellar, T; Fekete, J; Rakonjac, A; Deb, A B; Kjærgaard, N

    2014-04-01

    We report on the implementation of an optical tweezer system for controlled transport of ultracold atoms along a narrow, static confinement channel. The tweezer system is based on high-efficiency acousto-optic deflectors and offers two-dimensional control over beam position. This opens up the possibility for tracking the transport channel when shuttling atomic clouds along it, forestalling atom spilling. Multiple clouds can be tracked independently by time-shared tweezer beams addressing individual sites in the channel. The deflectors are controlled using a multichannel direct digital synthesizer, which receives instructions on a submicrosecond time scale from a field-programmable gate array. Using the tweezer system, we demonstrate sequential binary splitting of an ultracold 87Rb cloud into 2(5) clouds.

  6. Optical tweezers based on polarization interferometer

    NASA Astrophysics Data System (ADS)

    Angelsky, Oleg V.; Maksimyak, Andrew P.; Maksimyak, Peter P.; Dominikov, Mykola M.

    2013-06-01

    In this paper, we propose optical tweezers based on a biaxial crystal. To control the movement of opaque particles, we use the shift polarization interferometer. The results of experimental study of laser tweezers are shown. We demonstrates movement of a microparticle of toner using singular-optical trap, rotate a particle due to orbital momentum, conversion of two traps when changing the plane of polarizer transmission and converging of two traps.

  7. Data-glove-based fuzzy control of piezoelectric forceps actuator

    NASA Astrophysics Data System (ADS)

    Susanto, Ken; Yang, Bingen

    2004-07-01

    This paper discusses a novel concept idea of utilizing smart structure in biomedical, minimum invasive surgery (MIS), MEMS manufacturing assembly line and also as a miniature robotic gripper system. The proposed prototype of a miniature piezoelectric forceps actuator (PFA) is composed of two symmetric slightly curved composite beams which each bonded with piezoelectric ceramic layer. The PFA is an innovative forceps actuator that comes with a data glove. The data glove is simply a custom-made glove with two embedded resistance-bending sensors located on thumb and index fingers. Any users can control opening and closing of the PFA by just wearing the data glove. A thin curved beam theory bonded with piezoelectric ceramic will be derived based on Hamilton's principle and its deflection behavior will be simulated based on distributed transfer function method (DTFM). A feasibility study of simulation open loop data glove-based fuzzy logic controller allows the user to open and close the PFA remotely. The bending movement of the thumb and index finger will be formulated in a table of rules based to produce the necessary output controller gain to control the PFA.

  8. Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy

    PubMed Central

    Neuman, Keir C.; Nagy, Attila

    2012-01-01

    Single-molecule force spectroscopy has emerged as a powerful tool to investigate the forces and motions associated with biological molecules and enzymatic activity. The most common force spectroscopy techniques are optical tweezers, magnetic tweezers and atomic force microscopy. These techniques are described and illustrated with examples highlighting current capabilities and limitations. PMID:18511917

  9. Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy.

    PubMed

    Neuman, Keir C; Nagy, Attila

    2008-06-01

    Single-molecule force spectroscopy has emerged as a powerful tool to investigate the forces and motions associated with biological molecules and enzymatic activity. The most common force spectroscopy techniques are optical tweezers, magnetic tweezers and atomic force microscopy. Here we describe these techniques and illustrate them with examples highlighting current capabilities and limitations.

  10. Compact forceps manipulator using friction wheel mechanism and gimbals mechanism for laparoscopic surgery.

    PubMed

    Suzuki, Takashi; Katayama, Youichi; Kobayashi, Etsuko; Sakuma, Ichiro

    2005-01-01

    This paper reports evaluation of compact forceps manipulator designed for assisting laparoscopic surgery. The manipulator consists of two miniaturized parts; friction wheel mechanism which rotates and translates forceps (62 x 52 x 150[mm3], 0.6 [kg]), and gimbals mechanism which provides pivoting motion of forceps around incision hole on the abdomen (135 x 165 x 300 [mm3], 1.1 [kg]). The four-DOF motion of forceps around the incision hole on the abdomen in laparoscopic surgery is realized. By integration with robotized forceps or a needle insertion robot, it will work as a compact robotic arm in a master-slave system. It can also work under numerical control based on the computerized surgical planning. This table-mounted miniaturized manipulator contributes to the coexistence of clinical staffs and manipulators in the today's crowded operating room. As the results of mechanical performance evaluation with load of 4 [N], positioning accuracy was less than 1.2 [deg] in pivoting motion, less than 4 [deg] in rotation of forceps, less than 1.2 [mm] in longitudinal translation of forceps. As future works, we will modify mechanism for sterilization and safety improvement, and also integrate this manipulator with robotized forceps to build a surgery assisting robotic system.

  11. The first picture of a dental forceps in a printed book.

    PubMed

    Ring, Malvin E

    2004-03-01

    Niccolo Leonico Tomeo authored numerous volumes on a variety of themes, and was principally responsible for reintroducing the works of Aristotle in the original Greek. In one of Tomeo's works, he included a picture of forceps holding an extracted tooth. This was the first time a forceps was pictured in a printed book.

  12. 21 CFR 868.5420 - Ether hook.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ether hook. 868.5420 Section 868.5420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5420 Ether hook. (a) Identification. An ether hook is a...

  13. 21 CFR 878.5360 - Tweezer-type epilator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... (a) Identification. The tweezer-type epilator is an electrical device intended to remove hair. The energy provided at the tip of the tweezer used to remove hair may be radio frequency, galvanic...

  14. 21 CFR 878.5360 - Tweezer-type epilator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    .... (a) Identification. The tweezer-type epilator is an electrical device intended to remove hair. The energy provided at the tip of the tweezer used to remove hair may be radio frequency, galvanic...

  15. 21 CFR 878.5360 - Tweezer-type epilator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... (a) Identification. The tweezer-type epilator is an electrical device intended to remove hair. The energy provided at the tip of the tweezer used to remove hair may be radio frequency, galvanic...

  16. 21 CFR 878.5360 - Tweezer-type epilator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... (a) Identification. The tweezer-type epilator is an electrical device intended to remove hair. The energy provided at the tip of the tweezer used to remove hair may be radio frequency, galvanic...

  17. 21 CFR 878.5360 - Tweezer-type epilator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... (a) Identification. The tweezer-type epilator is an electrical device intended to remove hair. The energy provided at the tip of the tweezer used to remove hair may be radio frequency, galvanic...

  18. "Red Tweezers": Fast, customisable hologram generation for optical tweezers

    NASA Astrophysics Data System (ADS)

    Bowman, Richard W.; Gibson, Graham M.; Linnenberger, Anna; Phillips, David B.; Grieve, James A.; Carberry, David M.; Serati, Steven; Miles, Mervyn J.; Padgett, Miles J.

    2014-01-01

    Holographic Optical Tweezers (HOT) are a versatile way of manipulating microscopic particles in 3D. However, their ease of use has been hampered by the computational load of calculating the holograms, resulting in an unresponsive system. We present a program for generating these holograms on a consumer Graphics Processing Unit (GPU), coupled to an easy-to-use interface in LabVIEW (National Instruments). This enables a HOT system to be set up without writing any additional code, as well as providing a platform enabling the fast generation of other holograms. The GPU engine calculates holograms over 300 times faster than the same algorithm running on a quad core CPU. The hologram algorithm can be altered on-the-fly without recompiling the program, allowing it to be used to control Spatial Light Modulators in any situation where the hologram can be calculated in a single pass. The interface has also been rewritten to take advantage of new features in LabVIEW 2010. It is designed to be easily modified and extended to integrate with hardware other than our own.

  19. Hooke, Robert (1635-1703)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Scientist, born in Freshwater, Isle of Wight, England, educated at Christ Church College, Oxford where he met Boyle and was employed by him to construct his air pump, became professor of geometry at Gresham College, London. Discovered Hooke's law of elasticity. Worked on optics, simple harmonic motion and elasticity in strings. Published a monograph called Micrographia, containing beautiful pict...

  20. Covariant Formulation of Hooke's Law.

    ERIC Educational Resources Information Center

    Gron, O.

    1981-01-01

    Introducing a four-vector strain and a four-force stress, Hooke's law is written as a four-vector equation. This formulation is shown to clarify seemingly paradoxical results in connection with uniformly accelerated motion, and rotational motion with angular acceleration. (Author/JN)

  1. Magnetic tweezers for the measurement of twist and torque.

    PubMed

    Lipfert, Jan; Lee, Mina; Ordu, Orkide; Kerssemakers, Jacob W J; Dekker, Nynke H

    2014-05-19

    Single-molecule techniques make it possible to investigate the behavior of individual biological molecules in solution in real time. These techniques include so-called force spectroscopy approaches such as atomic force microscopy, optical tweezers, flow stretching, and magnetic tweezers. Amongst these approaches, magnetic tweezers have distinguished themselves by their ability to apply torque while maintaining a constant stretching force. Here, it is illustrated how such a "conventional" magnetic tweezers experimental configuration can, through a straightforward modification of its field configuration to minimize the magnitude of the transverse field, be adapted to measure the degree of twist in a biological molecule. The resulting configuration is termed the freely-orbiting magnetic tweezers. Additionally, it is shown how further modification of the field configuration can yield a transverse field with a magnitude intermediate between that of the "conventional" magnetic tweezers and the freely-orbiting magnetic tweezers, which makes it possible to directly measure the torque stored in a biological molecule. This configuration is termed the magnetic torque tweezers. The accompanying video explains in detail how the conversion of conventional magnetic tweezers into freely-orbiting magnetic tweezers and magnetic torque tweezers can be accomplished, and demonstrates the use of these techniques. These adaptations maintain all the strengths of conventional magnetic tweezers while greatly expanding the versatility of this powerful instrument.

  2. Forceps or vacuum extraction? A comparison of effects on the newborn infant.

    PubMed

    Fall, O; Rydén, G; Finnström, K; Finnström, O; Leijon, I

    1986-01-01

    Sixteen women delivered by forceps and 20 women delivered by vacuum extraction (VE) owing to secondary uterine inertia were compared with a control group of 11 women who gave birth spontaneously. The cord arterial pH was lower in the VE group than in the forceps and control groups. Base deficit in both arterial and venous cord blood was greater in the VE group than in the forceps group, probably owing to the longer application and extraction times in VE than in forceps delivery. The incidence of retinal hemorrhage did not differ between the forceps and VE groups. The incidence of cephalhematomata was greater among VE infants than in the forceps and control groups. All infants were examined on the 1st and 5th day by standardized neurological and behavioural examination. There were no significant differences in neurological status between the forceps and VE groups. Thus, in low extraction with no signs of fetal asphyxia, either method can be used with safety if the obstetrician is familiar with both methods of operative vaginal delivery.

  3. Cytological Sampling Versus Forceps Biopsy During Percutaneous Transhepatic Biliary Drainage and Analysis of Factors Predicting Success

    SciTech Connect

    Tapping, C. R.; Byass, O. R.; Cast, J. E. I.

    2012-08-15

    Purpose: To assess the accuracy of cytological sampling and forceps biopsy in obstructing biliary lesions and to identify factors predictive of success. Methods: Consecutive patients (n = 119) with suspected malignant inoperable obstructive jaundice treated with percutaneous transhepatic biliary drainage during 7 years were included (60 male; mean age 72.5 years). All patients underwent forceps biopsy plus cytological sampling by washing the forceps device in cytological solution. Patient history, procedural and pathological records, and clinical follow-up were reviewed. Statistical analysis included chi-square test and multivariate regression analysis. Results: Histological diagnosis after forceps biopsy was more successful than cytology: Sensitivity was 78 versus 61%, and negative predictive value was 30 versus 19%. Cytology results were never positive when the forceps biopsy was negative. The cytological sample was negative and forceps sample positive in 2 cases of cholangiocarcinoma, 16 cases of pancreatic carcinoma, and 1 case of benign disease. Diagnostic accuracy was predicted by low bilirubin (p < 0.001), aspartate transaminase (p < 0.05), and white cell count (p {<=} 0.05). Conclusions: This technique is safe and effective and is recommended for histological diagnosis during PTBD in patients with inoperable malignant biliary strictures. Diagnostic yield is greater when bilirubin levels are low and there is no sepsis; histological diagnosis by way of forceps biopsy renders cytological sampling unnecessary.

  4. Quantum computation architecture using optical tweezers

    SciTech Connect

    Weitenberg, Christof; Kuhr, Stefan; Moelmer, Klaus; Sherson, Jacob F.

    2011-09-15

    We present a complete architecture for scalable quantum computation with ultracold atoms in optical lattices using optical tweezers focused to the size of a lattice spacing. We discuss three different two-qubit gates based on local collisional interactions. The gates between arbitrary qubits require the transport of atoms to neighboring sites. We numerically optimize the nonadiabatic transport of the atoms through the lattice and the intensity ramps of the optical tweezer in order to maximize the gate fidelities. We find overall gate times of a few 100 {mu}s, while keeping the error probability due to vibrational excitations and spontaneous scattering below 10{sup -3}. The requirements on the positioning error and intensity noise of the optical tweezer and the magnetic field stability are analyzed and we show that atoms in optical lattices could meet the requirements for fault-tolerant scalable quantum computing.

  5. Micro-objective manipulated with optical tweezers

    SciTech Connect

    Sasaki, M.; Kurosawa, T.; Hane, K.

    1997-02-01

    A microscope is described that uses a {mu}m-sized ball lens, which is here termed micro-objective, manipulated with optical tweezers to image the side view of the arbitrary region of a sample. Since this micro-objective is small in size, it can go into a concave region to produce a local image of the inside which the conventional microscope cannot observe. Preliminary results show good lens performance from the micro-objective when combined with optical tweezers. {copyright} {ital 1997 American Institute of Physics.}

  6. Origin and Future of Plasmonic Optical Tweezers

    PubMed Central

    Huang, Jer-Shing; Yang, Ya-Tang

    2015-01-01

    Plasmonic optical tweezers can overcome the diffraction limits of conventional optical tweezers and enable the trapping of nanoscale objects. Extension of the trapping and manipulation of nanoscale objects with nanometer position precision opens up unprecedented opportunities for applications in the fields of biology, chemistry and statistical and atomic physics. Potential applications include direct molecular manipulation, lab-on-a-chip applications for viruses and vesicles and the study of nanoscale transport. This paper reviews the recent research progress and development bottlenecks and provides an overview of possible future directions in this field. PMID:28347051

  7. Transverse arrest: a review of outcomes of rotational forceps and cesarean delivery at a single center.

    PubMed

    Leo; Odibo; Ling; Rodis; Borgida; Campbell

    1998-07-01

    Objective: To assess whether Kielland forceps rotational delivery causes a significant increase in maternal or perinatal morbidity in comparison with cesarean delivery in the clinical situation of transverse arrest. Rotational forceps delivery has been reported to have unacceptably high maternal and neonatal complication rates when compared with either spontaneous vaginal delivery or non-rotational forceps delivery. Clinically, however, we considered the more relevant comparison between Kielland rotational forceps delivery and cesarean delivery as these are generally the two modes of delivery for the fetus in transverse arrest.Study Design: The charts of all the mothers delivered by Kielland forceps or cesarean delivery for the main indication of transverse arrest between July 1995 and June 1996 were reviewed. The following were evaluated: Apgar scores at 1 and 5 minutes, cord pH, birth weight, neonatal superficial facial laceration or bruising, bone or nerve injuries, maternal injuries, 3rd and 4th degree perineal or vaginal lacerations, post-partum fever. Statistical analysis was by chi(2) (for Apgar scores), two-tailed Fisher Exact test (for post-partum fever), and t test (for birth weight and cord pH). A P value <.05 was considered statistically significant.Results: Fifty-two Kielland forceps and 30 cesarean deliveries were performed. One-minute Apgar scores of less than or equal to 7 were noted in 11.5% and 6.7% of the forceps and cesarean section groups, respectively (P = NS); mean arterial cord pH was 7.26 for both groups; no cases of post-partum fever were noted in the forceps versus 16% in the cesarean group (P <.05); the mean weight was 3,316 and 3,569 g for the forceps and cesarean group, respectively (P <.05). The Kielland group was also characterized by the following: 19 facial bruising and 2 temporary facial nerve injury (resolved by the time of discharge), 3 perineal lacerations, and 3 vaginal tears. No blood transfusions were required for either

  8. Molecular tweezers targeting transthyretin amyloidosis.

    PubMed

    Ferreira, Nelson; Pereira-Henriques, Alda; Attar, Aida; Klärner, Frank-Gerrit; Schrader, Thomas; Bitan, Gal; Gales, Luís; Saraiva, Maria João; Almeida, Maria Rosário

    2014-04-01

    Transthyretin (TTR) amyloidoses comprise a wide spectrum of acquired and hereditary diseases triggered by extracellular deposition of toxic TTR aggregates in various organs. Despite recent advances regarding the elucidation of the molecular mechanisms underlying TTR misfolding and pathogenic self-assembly, there is still no effective therapy for treatment of these fatal disorders. Recently, the "molecular tweezers", CLR01, has been reported to inhibit self-assembly and toxicity of different amyloidogenic proteins in vitro, including TTR, by interfering with hydrophobic and electrostatic interactions known to play an important role in the aggregation process. In addition, CLR01 showed therapeutic effects in animal models of Alzheimer's disease and Parkinson's disease. Here, we assessed the ability of CLR01 to modulate TTR misfolding and aggregation in cell culture and in an animal model. In cell culture assays we found that CLR01 inhibited TTR oligomerization in the conditioned medium and alleviated TTR-induced neurotoxicity by redirecting TTR aggregation into the formation of innocuous assemblies. To determine whether CLR01 was effective in vivo, we tested the compound in mice expressing TTR V30M, a model of familial amyloidotic polyneuropathy, which recapitulates the main pathological features of the human disease. Immunohistochemical and Western blot analyses showed a significant decrease in TTR burden in the gastrointestinal tract and the peripheral nervous system in mice treated with CLR01, with a concomitant reduction in aggregate-induced endoplasmic reticulum stress response, protein oxidation, and apoptosis. Taken together, our preclinical data suggest that CLR01 is a promising lead compound for development of innovative, disease-modifying therapy for TTR amyloidosis.

  9. MatLab program for precision calibration of optical tweezers

    NASA Astrophysics Data System (ADS)

    Tolić-Nørrelykke, Iva Marija; Berg-Sørensen, Kirstine; Flyvbjerg, Henrik

    2004-06-01

    Optical tweezers are used as force transducers in many types of experiments. The force they exert in a given experiment is known only after a calibration. Computer codes that calibrate optical tweezers with high precision and reliability in the ( x, y)-plane orthogonal to the laser beam axis were written in MatLab (MathWorks Inc.) and are presented here. The calibration is based on the power spectrum of the Brownian motion of a dielectric bead trapped in the tweezers. Precision is achieved by accounting for a number of factors that affect this power spectrum. First, cross-talk between channels in 2D position measurements is tested for, and eliminated if detected. Then, the Lorentzian power spectrum that results from the Einstein-Ornstein-Uhlenbeck theory, is fitted to the low-frequency part of the experimental spectrum in order to obtain an initial guess for parameters to be fitted. Finally, a more complete theory is fitted, a theory that optionally accounts for the frequency dependence of the hydrodynamic drag force and hydrodynamic interaction with a nearby cover slip, for effects of finite sampling frequency (aliasing), for effects of anti-aliasing filters in the data acquisition electronics, and for unintended "virtual" filtering caused by the position detection system. Each of these effects can be left out or included as the user prefers, with user-defined parameters. Several tests are applied to the experimental data during calibration to ensure that the data comply with the theory used for their interpretation: Independence of x- and y-coordinates, Hooke's law, exponential distribution of power spectral values, uncorrelated Gaussian scatter of residual values. Results are given with statistical errors and covariance matrix. Program summaryTitle of program: tweezercalib Catalogue identifier: ADTV Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland. Program Summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTV Computer for

  10. Surgical treatment of incarcerated calculi via laparoscopic bile duct exploration using laparotomy biliary lithotomy forceps

    PubMed Central

    Jiang, H.; Wang, S. Y.; Jin, X. L.; Jin, J. C.; Gu, H. B.; Zhang, F. M.

    2016-01-01

    The present study aimed to investigate the practicability and clinical value of applying laparotomy biliary lithotomy forceps to laparoscopic bile duct exploration (LCBDE) for the surgical treatment of incarcerated calculi. A total of 63 patients were diagnosed with cholecystolithiasis and choledocholithiasis. The present study performed a retrospective analysis of clinical samples from 16 of these patients who had incarcerated calculi at the terminus of the common bile duct, and who had been treated with laparoscopic cholecystectomy and LCBDE. During the procedure, laparotomy biliary lithotomy forceps were used to gently remove the calculi from the common bile duct. Of the surgical procedures that used laparotomy biliary lithotomy forceps, one case was unsuccessful and 15 cases were successful. The results of the present study suggested that it may be clinically advisable to use laparotomy biliary lithotomy forceps to remove incarcerated calculi from the common bile duct during a laparoscopy, since it is easy, economical and effective. PMID:27698730

  11. A force calibration standard for magnetic tweezers

    NASA Astrophysics Data System (ADS)

    Yu, Zhongbo; Dulin, David; Cnossen, Jelmer; Köber, Mariana; van Oene, Maarten M.; Ordu, Orkide; Berghuis, Bojk A.; Hensgens, Toivo; Lipfert, Jan; Dekker, Nynke H.

    2014-12-01

    To study the behavior of biological macromolecules and enzymatic reactions under force, advances in single-molecule force spectroscopy have proven instrumental. Magnetic tweezers form one of the most powerful of these techniques, due to their overall simplicity, non-invasive character, potential for high throughput measurements, and large force range. Drawbacks of magnetic tweezers, however, are that accurate determination of the applied forces can be challenging for short biomolecules at high forces and very time-consuming for long tethers at low forces below ˜1 piconewton. Here, we address these drawbacks by presenting a calibration standard for magnetic tweezers consisting of measured forces for four magnet configurations. Each such configuration is calibrated for two commonly employed commercially available magnetic microspheres. We calculate forces in both time and spectral domains by analyzing bead fluctuations. The resulting calibration curves, validated through the use of different algorithms that yield close agreement in their determination of the applied forces, span a range from 100 piconewtons down to tens of femtonewtons. These generalized force calibrations will serve as a convenient resource for magnetic tweezers users and diminish variations between different experimental configurations or laboratories.

  12. Redundant Toggle/Hook Release Mechanism

    NASA Technical Reports Server (NTRS)

    Graves, Thomas J.; Brown, Christopher W.

    1991-01-01

    Release mechanism ensures reliable separation of structural members while imparting minimal impulse to members. Includes set of three hooks and pistons holding toggle and thereby clamp plate to body of mechanism. In locked position, pistons down, and hooks held against toggle. In unlocked position, pistons up. Notches in pistons let hook swivel on pivot pins. Functions even when two of its three key elements fail.

  13. Comparison of thermal coagulation profiles for bipolar forceps with different cooling mechanisms in a porcine model of spinal surgery

    PubMed Central

    Chen, Roland K.; Than, Khoi D.; Wang, Anthony C.; Park, Paul; Shih, Albert J.

    2013-01-01

    Background: Coagulation accomplished using bipolar forceps is common in neurosurgery. Control of thermal spread from the forceps tips into surrounding neural tissues is a persistent concern, as neural tissues are especially vulnerable to heat injury. The purpose of our investigation was to compare the efficacy of cooling mechanisms for four different bipolar forceps and to understand thermal spread when coagulating vessels on the spinal cord. Methods: Immediately following euthanasia, the dura mater of an ex vivo porcine model was opened to expose vessels on the spinal cord for coagulation. Temperature profiles were measured at generator power of 25 W and at fixed 5-second activation times. The bipolar forceps used in this study included regular stainless steel, titanium, heat-pipe embedded, and SILVERGlide forceps. Temperature was measured by micro-thermistor at the midpoint between the bipolar tips, and 1 and 2 mm away from the midpoint along the centerline. Statistical analysis was performed to evaluate temperature differences. Results: Temperature profiles indicated that heat-pipe embedded forceps create the least amount of temperature increase and the highest normalized temperature decreasing slope after activation. The decreasing slope of SILVERGlide forceps is slightly higher than that of regular stainless steel forceps. Conclusions: Bipolar forceps incorporating either heat-pipe embedded technology or SILVERGlide coating can effectively limit excessive thermal spread, thus decreasing potential injury to adjacent tissues when compared with standard stainless steel and titanium bipolar forceps. Of the two, heat-pipe embedded technology appeared safest, having better cooling efficiency at higher temperature. PMID:24083049

  14. The Twin Forceps: A New Instrument for SILS

    PubMed Central

    Rizzuto, Antonia; Donnici, Mario; Nudo, Paola; Sinopoli, Basilio; Sacco, Rosario; Danieli, Guido

    2015-01-01

    In the last ten years, the single incision laparoscopic surgery (SILS) is gaining more interest than the traditional laparoscopic surgery (LAP). Many studies make a comparison between the performances of the SILS and the LAP. The results show that the single incision laparoscopic surgery reduces pain, length of period of postoperative hospitalization, and loss of blood. This technique is also able to reduce the infection sites. In spite of many advantages, SILS reveals some problems: laparoscopic instruments triangulation and small workspace. The surgeon has to be more skillful to make a surgery in SILS because the surgeon has only three laparoscopic instruments and only one hole in the abdomen cavity. In this paper, a novel laparoscopic instrument to help the surgeon during a SILS operation is presented. This instrument is innovative forceps with double graspers. Different designs of this instrument are presented, with the final one which greatly simplifies both construction and operation. The initial experience in the laboratory with the innovative instrument is presented. The surgeon experienced in laparoscopic surgery and with the help of assistants performed a training program based on predetermined task performed in simulation box (laparoscopic box-trainer). PMID:26346966

  15. Instability of hooks during bacterial flagellar swimming

    NASA Astrophysics Data System (ADS)

    Jabbarzadeh, Mehdi; Fu, Henry C.; Henry Fu Team

    2016-11-01

    In bacteria, a flexible hook transmits torque from the rotary motor at the cell body to the flagellum. Previously, the hook has been modeled as a Kirchhoff rod between the cell body and rotating flagellum. To study effects of the hook's flexibility on the bacteria's swimming speed and trajectory for wide range hook stiffnesses and flagellum configurations, we develop an efficient simplified spring model for the hook by linearizing the Kirchhoff rod. We treat the hydrodynamics of the cell body and helical flagellum using resistance matrices calculated by the method of regularized Stokeslets. We investigate flagellar and swimming dynamics for a range of hook flexibilities and flagellar orientations relative to the cell body and compare the results to models without hook flexibility. We investigate in detail parameters corresponding to E. coli and Vibrio alginolyticus. Generally, the flagellum changes orientation relative to the cell body, undergoing an orbit with the period of the motor rotation. We find that as the hook stiffness decreases, steady-state orbits of the flagellum first become unstable before the hook buckles, which may suggest a new mechanism of flick initiation in run-reverse-flick motility. We also find that for some parameter ranges, there are multiple stable steady state orbits, which may have implications for the tumbling and turning of bacteria.

  16. Two new cave rnicolous genera of Julidae (Diplopoda, Julida), with notes on the tribe Brachyiulini and on julid subanal hooks and anchors.

    PubMed

    Akkari, Nesrine; Stoev, Pavel; Enghoff, Henrik

    2011-01-01

    Two remarkable genera and species of the millipede family Julidae, Titanophyllum spiliarumgen. n., sp. n. and Mammamia profugagen. n. sp., n., are described from caves in Greece and Italy, respectively. The presence of a flagellum and the absence of a 'pro-mesomerital forceps' on the gonopods place them in the tribe Brachyiulini Verhoeff, 1909, an unnatural grouping based on plesiomorphic characters. Both are outstanding in being the only hitherto known blind julidans having such gonopodal features. A dichotomous key to the nine valid brachyiulinine genera based on peripheral and gonopodal characters is presented. Moreover, notes on subanal hooks and anchors in Julida are provided with hypotheses on their possible function.

  17. Survival of foul-hooked largemouth bass (Micropterus salmoides)

    USGS Publications Warehouse

    Pope, K.L.; Wilde, G.R.

    2010-01-01

    We conducted a field experiment to determine the survival rate of foul-hooked (hooked external to the oral cavity) largemouth bass (Micropterus salmoides) caught and released by recreational anglers. Of 42 largemouth bass caught with hard-plastic baits containing three treble hooks, 15 were hooked only within the mouth and 27 had at least one hook penetrating the external surface of the fish (i.e., foul-hooked). There was no difference in survival of mouth-hooked (100%), foul-hooked (100%), or control (100%) largemouth bass.

  18. What is Hooking Up? Examining Definitions of Hooking Up in Relation to Behavior and Normative Perceptions

    PubMed Central

    Lewis, Melissa A.; Atkins, David C.; Blayney, Jessica A.; Dent, David V.; Kaysen, Debra L.

    2012-01-01

    Research has demonstrated ambiguity about the definition of hooking up among college students. The current research examined whether there were multiple hooking up definitions among college students and how different definitions might be associated with participant's own hooking up behavior and normative perceptions of peer hooking up behavior. A random sample (N = 1,468) of undergraduates (56.4% female) completed a Web-based survey that was comprised of measures of drinking and sexual behavior. Open-ended definitions of hooking up were content coded and analyzed using a mixture model to explore discrete definitions of hooking up among college students. Findings indicated three clusters of student definitions of hooking up. Cluster 1 had the broadest definition, referring to sex in general, not specific sexual acts, and to making out. Cluster 2 placed an emphasis on interpersonal and social aspects. Cluster 3 defined hooking up as sex with notable references to specific sexual acts. Results further indicated that hooking up behavior and normative perceptions differentiated these three groups of definitions. Clinical implications regarding the inconsistency of student definitions of hooking up and how they may impact negative consequences associated with hooking up are discussed. PMID:23057805

  19. Parachute Line Hook Includes Integral Loop Expander

    NASA Technical Reports Server (NTRS)

    Bayless, G. B.

    1983-01-01

    Parachute packing simplified with modified line hook. One person packs parachutes for test recovery vehicles faster than previously two-person team. New line hook includes expander that opens up two locking loops so parachute lines are pulled through them. Parachutes are packed at high pressure to be compressed into limited space available in test vehicles.

  20. Relationship between Religiosity and "Hooking Up" Behavior

    ERIC Educational Resources Information Center

    Penhollow, Tina; Young, Michael; Bailey, William

    2007-01-01

    Background: "Hooking up" behaviors, or sexual activities without commitment or emotional attachment, are occurring among college students. Purpose: This study examined the relationship between hooking up and two measures of religiosity. Methods: Data was obtained from students at a mid-southern university (n=459). Results: Most respondents…

  1. Independent trapping and manipulation of microparticles using dexterous acoustic tweezers

    NASA Astrophysics Data System (ADS)

    Courtney, Charles R. P.; Demore, Christine E. M.; Wu, Hongxiao; Grinenko, Alon; Wilcox, Paul D.; Cochran, Sandy; Drinkwater, Bruce W.

    2014-04-01

    An electronically controlled acoustic tweezer was used to demonstrate two acoustic manipulation phenomena: superposition of Bessel functions to allow independent manipulation of multiple particles and the use of higher-order Bessel functions to trap particles in larger regions than is possible with first-order traps. The acoustic tweezers consist of a circular 64-element ultrasonic array operating at 2.35 MHz which generates ultrasonic pressure fields in a millimeter-scale fluid-filled chamber. The manipulation capabilities were demonstrated experimentally with 45 and 90-μm-diameter polystyrene spheres. These capabilities bring the dexterity of acoustic tweezers substantially closer to that of optical tweezers.

  2. Independent trapping and manipulation of microparticles using dexterous acoustic tweezers

    SciTech Connect

    Courtney, Charles R. P.; Demore, Christine E. M.; Wu, Hongxiao; Cochran, Sandy; Grinenko, Alon; Wilcox, Paul D.; Drinkwater, Bruce W.

    2014-04-14

    An electronically controlled acoustic tweezer was used to demonstrate two acoustic manipulation phenomena: superposition of Bessel functions to allow independent manipulation of multiple particles and the use of higher-order Bessel functions to trap particles in larger regions than is possible with first-order traps. The acoustic tweezers consist of a circular 64-element ultrasonic array operating at 2.35 MHz which generates ultrasonic pressure fields in a millimeter-scale fluid-filled chamber. The manipulation capabilities were demonstrated experimentally with 45 and 90-μm-diameter polystyrene spheres. These capabilities bring the dexterity of acoustic tweezers substantially closer to that of optical tweezers.

  3. Flagellar hook protein from Salmonella SJ25.

    PubMed

    Kagawa, H; Owaribe, K; Asakura, S; Takahashi, N

    1976-01-01

    From acid-disintegrated flagellar hooks of Salmonella SJ25 an immunochemically pure preparation of hook protein was obtained by column chromatography. The molecular weight of the protein determined by sodium dodecyl sulfate-gel electrophoresis was 43,000, whereas that of SJ25 flagellin was 56,000. The amino-terminal residue of the hook protein was determined to be seryl. The amino acid composition of the protein was determined, the results being very similar to that for an Escheria coli hook protein reported by Silverman and Simon (1972). Within a wavelength range of 200 to 250 nm, our purified preparation of hook protein gave a circular dichroism spectrum with unusually small amplitudes, suggesting that the alpha-helix content of the protein was very low.

  4. Cooling system for three hook ring segment

    DOEpatents

    Campbell, Christian X.; Eng, Darryl; Lee, Ching-Pang; Patat, Harry

    2014-08-26

    A triple hook ring segment including forward, midsection and aft mounting hooks for engagement with respective hangers formed on a ring segment carrier for supporting a ring segment panel, and defining a forward high pressure chamber and an aft low pressure chamber on opposing sides of the midsection mounting hook. An isolation plate is provided on the aft side of the midsection mounting hook to form an isolation chamber between the aft low pressure chamber and the ring segment panel. High pressure air is supplied to the forward chamber and flows to the isolation chamber through crossover passages in the midsection hook. The isolation chamber provides convection cooling air to an aft portion of the ring segment panel and enables a reduction of air pressure in the aft low pressure chamber to reduce leakage flow of cooling air from the ring segment.

  5. Designing physics video hooks for science students

    NASA Astrophysics Data System (ADS)

    McHugh, M.; McCauley, V.

    2016-01-01

    This paper offers an insight into the design structure of physics video hooks that were developed by the Science Education Resource design team in the school of education (SOE) in National University of Ireland, Galway (NUI Galway). A hook, is an instructional technique used to stimulate student attention (Hunter 1994, Lemov 2010), interest (Jewett 2013) and engagement (McCrory 2011, Riendeau 2013). The physics video hooks followed a design framework that is illustrated below by breaking down the centre of gravity (COG) hook. Various design principles and elements embedded within the COG hook are presented with examples and the time they occur within the video. The intention of this article is that the design can be replicated and modified to aid teachers and designers in the development of a multitude of classroom based multimedia resources.

  6. Pipe lifting hook having clamp assembly

    SciTech Connect

    Codner, J.A.

    1984-06-12

    A pipe lifting hook is provided having a generally ''C'' shaped hook member having an elongated lower portion being insertable within the end of a joint of pipe and having an upper portion positionable above the pipe and provided with lifting connection means. The hook member is frictionally clamped to the pipe by grip shoe means that is movably supported by the upper portion of the hook member and is selectably movable from a released position out of contact with said pipe to a locked position in frictional locking engagement with the outer surface of the pipe. A ratchet mechanism couples said grip shoe means to the upper portion of the hook member and is manually positionable to lock said grip shoe means at said locked position or release said grip shoe means for movement toward said released position thereof.

  7. Optoelectronic tweezers for microparticle and cell manipulation

    NASA Technical Reports Server (NTRS)

    Wu, Ming Chiang (Inventor); Chiou, Pei Yu (Inventor); Ohta, Aaron T. (Inventor)

    2009-01-01

    An optical image-driven light induced dielectrophoresis (DEP) apparatus and method are described which provide for the manipulation of particles or cells with a diameter on the order of 100 .mu.m or less. The apparatus is referred to as optoelectric tweezers (OET) and provides a number of advantages over conventional optical tweezers, in particular the ability to perform operations in parallel and over a large area without damage to living cells. The OET device generally comprises a planar liquid-filled structure having one or more portions which are photoconductive to convert incoming light to a change in the electric field pattern. The light patterns are dynamically generated to provide a number of manipulation structures that can manipulate single particles and cells or groups of particles/cells. The OET preferably includes a microscopic imaging means to provide feedback for the optical manipulation, such as detecting position and characteristics wherein the light patterns are modulated accordingly.

  8. Optoelectronic Tweezers for Microparticle and Cell Manipulation

    NASA Technical Reports Server (NTRS)

    Wu, Ming Chiang (Inventor); Chiou, Pei-Yu (Inventor); Ohta, Aaron T. (Inventor)

    2014-01-01

    An optical image-driven light induced dielectrophoresis (DEP) apparatus and method are described which provide for the manipulation of particles or cells with a diameter on the order of 100 micromillimeters or less. The apparatus is referred to as optoelectric tweezers (OET) and provides a number of advantages over conventional optical tweezers, in particular the ability to perform operations in parallel and over a large area without damage to living cells. The OET device generally comprises a planar liquid-filled structure having one or more portions which are photoconductive to convert incoming light to a change in the electric field pattern. The light patterns are dynamically generated to provide a number of manipulation structures that can manipulate single particles and cells or group of particles/cells. The OET preferably includes a microscopic imaging means to provide feedback for the optical manipulation, such as detecting position and characteristics wherein the light patterns are modulated accordingly.

  9. Exploring unconventional capabilities of holographic tweezers

    NASA Astrophysics Data System (ADS)

    Hernandez, R. J.; Pagliusi, P.; Provenzano, C.; Cipparrone, G.

    2011-06-01

    We report an investigation of manipulation and trapping capabilities of polarization holographic tweezers. A polarization gradient connected with a modulation of the ellipticity shows an optical force related to the polarization of the light that can influence optically isotropic particles. While in the case of birefringent particles an unconventional trapping in circularly polarized fringes is observed. A liquid crystal emulsion has been adopted to investigate the capabilities of the holographic tweezers. The unusual trapping observed for rotating bipolar nematic droplets has suggested the involvement of the lift hydrodynamic force responsible of the Magnus effect, originating from the peculiar optical force field. We show that the Magnus force which is ignored in the common approach can contribute to unconventional optohydrodynamic trapping and manipulation.

  10. The Smallest Tweezers in the World

    ERIC Educational Resources Information Center

    Lewalle, Alexandre

    2008-01-01

    A pair of fine tweezers and a steady hand may well be enough to pick up a grain of sand, but what would you use to hold something hundreds of times smaller still, the size of only one micron? The answer is to use a device that is not mechanical in nature but that relies instead on the tiny forces that light exerts on small particles: "optical…

  11. Tweezers for Chimeras in Small Networks

    NASA Astrophysics Data System (ADS)

    Omelchenko, Iryna; Omel'chenko, Oleh E.; Zakharova, Anna; Wolfrum, Matthias; Schöll, Eckehard

    2016-03-01

    We propose a control scheme which can stabilize and fix the position of chimera states in small networks. Chimeras consist of coexisting domains of spatially coherent and incoherent dynamics in systems of nonlocally coupled identical oscillators. Chimera states are generally difficult to observe in small networks due to their short lifetime and erratic drifting of the spatial position of the incoherent domain. The control scheme, like a tweezer, might be useful in experiments, where usually only small networks can be realized.

  12. Fractal zone plate beam based optical tweezers

    PubMed Central

    Cheng, Shubo; Zhang, Xinyu; Ma, Wenzhuo; Tao, Shaohua

    2016-01-01

    We demonstrate optical manipulation with an optical beam generated by a fractral zone plate (FZP). The experimental results show that the FZP beam can simultaneously trap multiple particles positioned in different focal planes of the FZP beam, owing to the multiple foci and self-reconstruction property of the FZP beam. The FZP beam can also be used to construct three-dimensional optical tweezers for potential applications. PMID:27678305

  13. New approaches in the design of magnetic tweezers-current magnetic tweezers

    NASA Astrophysics Data System (ADS)

    Bessalova, Valentina; Perov, Nikolai; Rodionova, Valeria

    2016-10-01

    The main advantages of the magnetic tweezers are the low price and simplicity of use. However the range of their application is reduced due to shortcomings like, for example, the remanent induction of the core and interaction between ferromagnetic cores. We present the new design of magnetic tweezers-Current Magnetic Tweezers (CMT) that allow particle manipulation by means of the magnetic field generated by the electric currents flowing through the non-magnetic wires. Arranging wires in different geometric shapes allows the particle movement either in two or three dimensions. Forces acting on the magnetic particles with the magnetic moment of 2·10-11 A m2 at distances up to 1 mm had been experimentally measured. It is established that a current of about 1 A at a 1 mm distance generates force of (approximately) 3 pN which is consistent with theoretical estimates.

  14. The Smallest Tweezers in the World

    NASA Astrophysics Data System (ADS)

    Lewalle, Alexandre

    2008-11-01

    A pair of fine tweezers and a steady hand may well be enough to pick up a grain of sand, but what would you use to hold something hundreds of times smaller still, the size of only one micron? The answer is to use a device that is not mechanical in nature but that relies instead on the tiny forces that light exerts on small particles: "optical tweezers." In recent years, this technique has become central to nanotechnology for the manipulation of small particles, even individual molecules. It is also an ideal illustration of how classroom physics is applied to cutting-edge research, combining concepts such as the vector nature of momentum and force, Newton's laws, optics, the wave-particle duality of light, and thermodynamics. The physics behind optical tweezers has many layers of complexity, but it can be reduced to a basic principle: the conservation of momentum. This paper guides the reader through a much simplified demonstration of this "tweezing effect" using a question-answer approach, leaving the reader with the choice to treat each step as a problem exercise.

  15. Analysis of voluntary opening Ottobock Hook and Hosmer Hook for upper limb prosthetics: a preliminary study.

    PubMed

    Hashim, Nur Afiqah; Abd Razak, Nasrul Anuar Bin; Gholizadeh, Hossein; Osman, Noor Azuan Abu

    2016-11-19

    There are a number of prosthetic terminal devices which offer functional restoration to individuals with upper limb deficiencies. Hosmer and Ottobock are major commercial hook providers for prosthetic terminal devices. The concern of this paper is to analyse the voluntary opening (VO) Ottobock model 10A18 and Hosmer model 99P hooks (one band) during opening operation and to find out favourable features in the design. Two tests were conducted to analyse the performance of both hooks. The first test used a simple bench tool to investigate cable excursion and hook opening angle and the second test used force sensor to find out the force supplied at a different hook opening angle. The study found that the average cable excursion for both hooks is approximately 30% less than the hook's opening span with the force at the hook's tip section being inversely proportional to the force at the lateral section. Ottobock 10A18 has a better control for grasping larger objects, while Hosmer 99P has the highest average force at the tip section but yet less efficient in generating adequate force for activities of daily living. Favourable features identified are low cable excursion per hook opening span and balance lateral to hook tip pinch force.

  16. The art of performing a safe forceps delivery: a skill to revitalise.

    PubMed

    Rather, Henna; Muglu, Javaid; Veluthar, Luxmi; Sivanesan, K

    2016-04-01

    The number of forceps deliveries is globally falling possibly due to Obstetricians gaining more experience and competence in the use of Ventouse deliveries. The declining use of traction forceps can increase the rate of second stage caesarean sections, which may have a long-term impact on the overall rate of vaginal births, despite the efforts of improving uptake of vaginal births after caesarean sections. The failures in forceps deliveries are commonly related to inaccurate assessment of the foetal position and station, which can be addressed by gaining sound clinical experience and applying intra-partum scanning to determine the fetal head position in the second stage, and should be part of the core curriculum in obstetric training. The alternate techniques of rotation, like digital and manual rotation, should be taught and encouraged in cases where rotation is required, which will significantly increase the success rate of instrumental deliveries.

  17. Evaluation of microsurgical tasks with OCT-guided and/or robot-assisted ophthalmic forceps.

    PubMed

    Yu, Haoran; Shen, Jin-Hui; Shah, Rohan J; Simaan, Nabil; Joos, Karen M

    2015-02-01

    Real-time intraocular optical coherence tomography (OCT) visualization of tissues with surgical feedback can enhance retinal surgery. An intraocular 23-gauge B-mode forward-imaging co-planar OCT-forceps, coupling connectors and algorithms were developed to form a unique ophthalmic surgical robotic system. Approach to the surface of a phantom or goat retina by a manual or robotic-controlled forceps, with and without real-time OCT guidance, was performed. Efficiency of lifting phantom membranes was examined. Placing the co-planar OCT imaging probe internal to the surgical tool reduced instrument shadowing and permitted constant tracking. Robotic assistance together with real-time OCT feedback improved depth perception accuracy. The first-generation integrated OCT-forceps was capable of peeling membrane phantoms despite smooth tips.

  18. Evaluation of microsurgical tasks with OCT-guided and/or robot-assisted ophthalmic forceps

    PubMed Central

    Yu, Haoran; Shen, Jin-Hui; Shah, Rohan J.; Simaan, Nabil; Joos, Karen M.

    2015-01-01

    Real-time intraocular optical coherence tomography (OCT) visualization of tissues with surgical feedback can enhance retinal surgery. An intraocular 23-gauge B-mode forward-imaging co-planar OCT-forceps, coupling connectors and algorithms were developed to form a unique ophthalmic surgical robotic system. Approach to the surface of a phantom or goat retina by a manual or robotic-controlled forceps, with and without real-time OCT guidance, was performed. Efficiency of lifting phantom membranes was examined. Placing the co-planar OCT imaging probe internal to the surgical tool reduced instrument shadowing and permitted constant tracking. Robotic assistance together with real-time OCT feedback improved depth perception accuracy. The first-generation integrated OCT-forceps was capable of peeling membrane phantoms despite smooth tips. PMID:25780736

  19. Writers Draw Visual Hooks: Children's Inquiry into Writing

    ERIC Educational Resources Information Center

    Leigh, S. Rebecca

    2012-01-01

    Drawing and writing in response to picturebook read-alouds, elementary children construct varying "visual hooks" in their sketches as effective visual devices for extending ideas for writing: the bubble hook, the zoom hook, and the group hook. This article reports on a 12-week qualitative study in which children in second grade develop as writers…

  20. Optical Tweezers Array and Nimble Tweezers Probe Generated by Spatial- Light Modulator

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.; Jassemnejad, Baha; Seibel, Robin E.; Weiland, Kenneth E.

    2003-01-01

    An optical tweezers is being developed at the NASA Glenn Research Center as a visiblelight interface between ubiquitous laser technologies and the interrogation, visualization, manufacture, control, and energization of nanostructures such as silicon carbide (SiC) nanotubes. The tweezers uses one or more focused laser beams to hold micrometer-sized particles called tools (sometimes called tips in atomic-force-microscope terminology). A strongly focused laser beam has an associated light-pressure gradient that is strong enough to pull small particles to the focus, in spite of the oppositely directed scattering force; "optical tweezers" is the common term for this effect. The objective is to use the tools to create carefully shaped secondary traps to hold and assemble nanostructures that may contain from tens to hundreds of atoms. The interaction between a tool and the nanostructures is to be monitored optically as is done with scanning probe microscopes. One of the initial efforts has been to create, shape, and control multiple tweezers beams. To this end, a programmable spatial-light modulator (SLM) has been used to modify the phase of a laser beam at up to 480 by 480 points. One program creates multiple, independently controllable tweezer beams whose shapes can be tailored by making the SLM an adaptive mirror in an interferometer (ref. 1). The beams leave the SLM at different angles, and an optical Fourier transform maps these beams to different positions in the focal plane of a microscope objective. The following figure shows two arrays of multiple beams created in this manner. The patterns displayed above the beam array control the intensity-to-phase transformation required in programming the SLM. Three of the seven beams displayed can be used as independently controllable beams.

  1. Kinematics of Hooke universal joint robot wrists

    NASA Technical Reports Server (NTRS)

    Mckinney, William S., Jr.

    1988-01-01

    The singularity problem associated with wrist mechanisms commonly found on industrial manipulators can be alleviated by redesigning the wrist so that it functions as a three-axis gimbal system. This paper discussess the kinematics of gimbal robot wrists made of one and two Hooke universal joints. Derivations of the resolved rate motion control equations for the single and double Hooke universal joint wrists are presented using the three-axis gimbal system as a theoretical wrist model.

  2. Reusable acoustic tweezers for disposable devices

    PubMed Central

    Guo, Feng; Xie, Yuliang; Li, Sixing; Lata, James; Ren, Liqiang; Mao, Zhangming; Ren, Baiyang; Wu, Mengxi; Ozcelik, Adem

    2015-01-01

    We demonstrate acoustic tweezers used for disposable devices. Rather than forming an acoustic resonance, we locally transmitted standing surface acoustic waves into a removable, independent polydimethylsiloxane (PDMS)-glass hybridized microfluidic superstrate device for micromanipulation. By configuring and regulating the displacement nodes on a piezoelectric substrate, cells and particles were effectively patterned and transported into said superstrate, accordingly. With the label-free and contactless nature of acoustic waves, the presented technology could offer a simple, accurate, low-cost, biocompatible, and disposable method for applications in the fields of point-of-care diagnostics and fundamental biomedical studies. PMID:26507411

  3. Absolute calibration of forces in optical tweezers

    NASA Astrophysics Data System (ADS)

    Dutra, R. S.; Viana, N. B.; Maia Neto, P. A.; Nussenzveig, H. M.

    2014-07-01

    Optical tweezers are highly versatile laser traps for neutral microparticles, with fundamental applications in physics and in single molecule cell biology. Force measurements are performed by converting the stiffness response to displacement of trapped transparent microspheres, employed as force transducers. Usually, calibration is indirect, by comparison with fluid drag forces. This can lead to discrepancies by sizable factors. Progress achieved in a program aiming at absolute calibration, conducted over the past 15 years, is briefly reviewed. Here we overcome its last major obstacle, a theoretical overestimation of the peak stiffness, within the most employed range for applications, and we perform experimental validation. The discrepancy is traced to the effect of primary aberrations of the optical system, which are now included in the theory. All required experimental parameters are readily accessible. Astigmatism, the dominant effect, is measured by analyzing reflected images of the focused laser spot, adapting frequently employed video microscopy techniques. Combined with interface spherical aberration, it reveals a previously unknown window of instability for trapping. Comparison with experimental data leads to an overall agreement within error bars, with no fitting, for a broad range of microsphere radii, from the Rayleigh regime to the ray optics one, for different polarizations and trapping heights, including all commonly employed parameter domains. Besides signaling full first-principles theoretical understanding of optical tweezers operation, the results may lead to improved instrument design and control over experiments, as well as to an extended domain of applicability, allowing reliable force measurements, in principle, from femtonewtons to nanonewtons.

  4. The Topic Is Sandy Hook: A Program for Gifted and Talented Students at Sandy Hook.

    ERIC Educational Resources Information Center

    Grant, David

    "The Topic Is Sandy Hook" is an experiential 10-week program designed to provide special opportunities and educational experiences for 6th to 10th grade gifted and talented students. Sandy Hook, a natural resource in Monmouth County, New Jersey, is unique in its physical and historical features and provides an exceptionally rich environment in…

  5. Two fault tolerant toggle-hook release

    NASA Technical Reports Server (NTRS)

    Graves, Thomas Joseph (Inventor); Brown, Christopher William (Inventor)

    1991-01-01

    A coupling device is disclosed which is mechanically two fault tolerant for release. The device comprises a fastener plate and fastener body, each of which is attachable to a different one of a pair of structures to be joined. The fastener plate and body are coupled by an elongate toggle mounted at one end in a socket on the fastener plate for universal pivotal movement thereon. The other end of the toggle is received in an opening in the fastener body and adapted for limited pivotal movement therein. The toggle is adapted to be restrained by three latch hooks arranged in symmetrical equiangular spacing about the axis of the toggle, each hook being mounted on the fastener body for pivotal movement between an unlatching non-contact position with respect to the toggle and a latching position in engagement with a latching surface of the toggle. The device includes releasable lock means for locking each latch hook in its latching position whereby the toggle couples the fastener plate to the fastener body and means for releasing the lock means to unlock each said latch hook from the latch position whereby the unlocking of at least one of the latch hooks from its latching position results in the decoupling of the fastener plate from the fastener body.

  6. Investigating the potential applications of a Raman tweezer system

    NASA Astrophysics Data System (ADS)

    Wray, John Casey

    This thesis describes the construction of an Optical Tweezer apparatus to be used in conjunction with a confocal Raman spectrometer. The tweezer utilizes an infrared (e=1064 nm) laser directed into an inverted microscope with NA=1.4 oil immersion 100x objective lens that strongly focuses the laser light into a sample to function as a single-beam gradient force trap. The long term goal of this research program is to develop a single molecule Raman tweezers apparatus that allows one to control the position of a Raman nanoplasmonic amplifier. This thesis describes the construction of the Raman tweezer apparatus along with several Raman spectra obtained from optically trapped samples of polystyrene fluorescent orange, amine-modified latex beads. In addition, I explored the Raman spectra of bulk cytochrome c mixed with or injected onto Ag aggregates for SERs enhancement.

  7. Subpiconewton dynamic force spectroscopy using magnetic tweezers.

    PubMed

    Kruithof, M; Chien, F; de Jager, M; van Noort, J

    2008-03-15

    We introduce a simple method for dynamic force spectroscopy with magnetic tweezers. This method allows application of subpiconewton force and twist control by calibration of the applied force from the height of the magnets. Initial dynamic force spectroscopy experiments on DNA molecules revealed a large hysteresis that is caused by viscous drag on the magnetic bead and will conceal weak interactions. When smaller beads are used, this hysteresis is sufficiently reduced to reveal intramolecular interactions at subpiconewton forces. Compared with typical quasistatic force spectroscopy, a significant reduction of measurement time is achieved, allowing the real-time study of transient structures and reaction intermediates. As a proof of principle, nucleosome-nucleosome interactions on a subsaturated chromatin fiber were analyzed.

  8. Multiplexed spectroscopy with holographic optical tweezers

    NASA Astrophysics Data System (ADS)

    Cibula, Matthew A.; McIntyre, David H.

    2014-09-01

    We have developed a multiplexed holographic optical tweezers system with an imaging spectrometer to manipulate multiple optically trapped nanosensors and detect multiple fluorescence spectra. The system uses a spatial light modulator (SLM) to control the positions of infrared optical traps in the sample so that multiple nanosensors can be positioned into regions of interest. Spectra of multiple nanosensors are detected simultaneously with the application of an imaging spectrometer. Nanosensors are capable of detecting changes in their environment such as pH, ion concentration, temperature, and voltage by monitoring changes in the nanosensors' emitted fluorescence spectra. We use streptavidin labeled quantum dots bound to the surface of biotin labeled polystyrene microspheres to measure temperature changes by observing a corresponding shift in the wavelength of the spectral peak. The fluorescence is excited at 532 nm with a wide field source.

  9. Drawings of fossils by Robert Hooke and Richard Waller

    PubMed Central

    Kusukawa, Sachiko

    2013-01-01

    The drawings of fossils by Robert Hooke and Richard Waller that were the basis of the engravings in Hooke's Posthumous works (1705) are published here for the first time. The drawings show that both Hooke and Waller were proficient draftsmen with a keen eye for the details of petrified objects. These drawings provided Hooke with a polemic edge in making the case for the organic origins of ‘figured stones’.

  10. Synthetic Minor NSR Permit: Van Hook Crude Terminal, LLC - Van Hook Crude Terminal/Rail Loading Facility

    EPA Pesticide Factsheets

    This page contains the current effective synthetic minor NSR permit for the Van Hook Crude Terminal, LLC, Van Hook Crude Terminal/Rail Loading Facility, located on the Fort Berthold Indian Reservation in Mountrail County, ND.

  11. 46 CFR 173.007 - Location of the hook load.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Location of the hook load. 173.007 Section 173.007... PERTAINING TO VESSEL USE Lifting § 173.007 Location of the hook load. When doing the calculations required in this subpart, the hook load must be considered to be located at the head of the crane....

  12. 29 CFR 1915.113 - Shackles and hooks.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... record which includes the date of such tests, the signature of the person who performed the test and an... and Materials Handling § 1915.113 Shackles and hooks. The provisions of this section shall apply to... various sizes and types of specific and identifiable hooks. All hooks for which no applicable...

  13. Education as a Practice of Freedom: Reflections on bell hooks

    ERIC Educational Resources Information Center

    Specia, Akello; Osman, Ahmed A.

    2015-01-01

    This paper critically analyses the conceptions of bell hooks on education. It focuses on the relevance of hook's ideas to the classroom. It is a theoretical paper based on secondary data that seeks to contribute to the growing body of knowledge in education. The paper is a reflection of hook's reaction to education as a practice of freedom, the…

  14. Primary esophageal mucosa-associated lymphoid tissue lymphoma diagnosed by using stacked forceps biopsy.

    PubMed

    Lee, D S; Ahn, Y C; Eom, D W; Lee, S J

    2016-10-01

    Non-Hodgkin lymphoma involving the esophagus is very rare. Only a few cases have been reported in the English literature to date, and it accounts for less than 1% of all cases of gastrointestinal lymphoma. As this malignancy manifests as a submucosal tumor, pathological diagnosis by using a simple endoscopic biopsy alone is difficult. Therefore, surgical biopsy, endoscopic mucosal resection, and endoscopic ultrasound-guided fine-needle aspiration have been used in most cases. Herein, we report a case of esophageal mucosa-associated lymphoid tissue lymphoma in a 49-year-old man, which involved the use of a stacked forceps biopsy to obtain adequate samples for pathological analysis; the use of the stacked forceps biopsy method is unlike those used in previous cases. The patient received cyclophosphamide, vincristine, and prednisolone chemotherapy; he achieved a complete response. In addition, we review the literature relevant to this case.

  15. Forceps insertion supporting system in laparoscopic surgery: image projection onto the abdominal surface

    NASA Astrophysics Data System (ADS)

    Koishi, Takeshi; Ushiki, Suguru; Nakaguchi, Toshiya; Hayashi, Hideki; Tsumura, Norimichi; Miyake, Yoichi

    2007-03-01

    Laparoscopic surgery without ventrotomy has been widely used in recent years for quick recovery and out of pain of patients. However, surgeons are required to accumulate various experiences for this surgery since the difficulty in perceiving the positions of tissues by the limited field of view (FOV) of laparoscopes and the operational difficulties of forceps. In this paper, we propose a new laparoscopic surgery supporting system using projected images. The image of the FOV of a laparoscope is projected directly onto the abdominal surface of a patient. The shape distortion of the projected images produced by the unevenness of the abdominal surface is corrected by grating projection. The distortion due to the viewing angle of the surgeon is also corrected by using an electromagnetic tracking sensor. It is shown that the proposed system is significant to laparoscopic surgery, particularly for forceps insertion, by experiments using a model of the abdomen made with a dry box.

  16. Improvement of tactile sensitivity by stochastic resonance effect--applications to surgical grasping forceps.

    PubMed

    Sueda, Yamato; Hattori, Minoru; Sawada, Hiroyuki; Egi, Hiroyuki; Ohdan, Hideki; Ueda, Jun; Tsuji, Toshio; Kurita, Yuichi

    2013-01-01

    This paper reports experimental results on a surgical grasping forceps with a vibration actuator that enhances a tactile perception ability. A short-time exposure of tactile receptors to sub-sensory white-noise vibration is known to improve perception ability. This phenomenon, called stochastic resonance (SR) in the somatosensory system, is expected to enhance the sense of touch when the weak vibration is applied to a fingertip, and thereby improve associated motor skills. A lead zirconate titanate (PZT) actuator was attached on the grip of surgical grasping forceps. A passive sensory test has been conducted for healthy subjects to confirm the efficacy of the device. Statistical significance has been observed when appropriate noise is applied. To investigate the effect of the noise intensity, a summing network of FitzHugh-Nagumo model neurons was built. The simulation results showed that a network with relatively large units can improve the detection capability of the input signal.

  17. Forceps, Actual Use, and Potential Cesarean Section Prevention: Study in a Selected Mexican Population

    PubMed Central

    Ayala-Yáñez, Rodrigo; Bayona-Soriano, Paulette; Hernández-Jimenez, Arturo; Contreras-Rendón, Alejandra; Chabat-Manzanera, Paulina; Nevarez-Bernal, Roberto

    2015-01-01

    Objective. Assessment of the frequency of complications observed with various forceps and operative vaginal delivery (OVD) techniques performed at the ABC Medical Center (Mexico City) to evaluate their safety, bearing in mind the importance of decreasing our country's high cesarean section incidence. Methods. We reviewed 5,375 deliveries performed between the years 2007 and 2012, only 146 were delivered by OVD.  Results. Only 1.0% of the cases had a serious, life-threatening situation (uterine rupture). The Simpson forceps was the most favored instrument (46%) due to its simplicity of use, effectiveness, and familiarity. Prophylactic use was the most common indication (30.8%) and significant complications observed were vaginal lacerations (p = 0.016), relative risk (RR) of 3.4 (95% confidence interval [CI]: 1.15–10.04), and fourth degree perineal tear (p = 0.016), RR of 3.4 (95% CI: 1.15–10.04). Conclusions. Forceps use and other OVD techniques are a safe alternative to be considered, diminishing C-section incidence and its complications. PMID:26380111

  18. Role of the Dc domain of the bacterial hook protein FlgE in hook assembly and function.

    PubMed

    Moriya, Nao; Minamino, Tohru; Ferris, Hedda U; Morimoto, Yusuke V; Ashihara, Masamichi; Kato, Takayuki; Namba, Keiichi

    2013-01-01

    The bacterial flagellar hook acts as a universal joint to smoothly transmit torque produced by the motor to the filament. The hook protein FlgE assembles into a 55 nm tubular structure with the help of the hook cap (FlgD). FlgE consists of four domains, D0, Dc, D1 and D2, arranged from the inner to the outer part of the tubular structure of the hook. The Dc domain contributes to the structural stability of the hook, but it is unclear how this Dc domain is responsible for the universal joint mechanism. Here, we carried out a deletion analysis of the FlgE Dc domain. FlgEΔ4/5 with deletion of residues 30 to 49 was not secreted into the culture media. FlgEΔ5 and FlgEΔ6 with deletions of residues 40 to 49 and 50 to 59, respectively, still formed hooks, allowing the export apparatus to export the hook-filament junction proteins FlgK and FlgL and flagellin FliC. However, these deletions inhibited the replacement of the FlgD hook cap by FlgK at the hook tip, thereby abolishing filament formation. Deletion of residues 50 to 59 significantly affected hook morphology. These results suggest that the Dc domain is responsible not only for hook assembly but also for FlgE export, the interaction with FlgK, and the polymorphic supercoiling mechanism of the hook.

  19. Laser tweezers Raman spectroscopy of single cells

    NASA Astrophysics Data System (ADS)

    Chen, De

    Raman scattering is an inelastic collision between the vibrating molecules inside the sample and the incident photons. During this process, energy exchange takes place between the photon and the scattering molecule. By measuring the energy change of the photon, the molecular vibration mode can be probed. The vibrational spectrum contains valuable information about the disposition of atomic nuclei and chemical bonds within a molecule, the chemical compositions and the interactions between the molecule and its surroundings. In this dissertation, laser tweezers Raman spectroscopy (LTRS) technique is applied for the analysis of biological cells and human cells at single cell level. In LTRS, an individual cell is trapped in aqueous medium with laser tweezers, and Raman scattering spectra from the trapped cell are recorded in real-time. The Raman spectra of these cells can be used to reveal the dynamical processes of cell growth, cell response to environment changes, and can be used as the finger print for the identification of a bacterial cell species. Several biophysical experiments were carried out using LTRS: (1) the dynamic germination process of individual spores of Bacillus thuringiensis was detected via Ca-DPA, a spore-specific biomarker molecule; (2) inactivation and killing of Bacillus subtilis spores by microwave irradiation and wet heat were studied at single cell level; (3) the heat shock activation process of single B. subtilis spores were analyzed, in which the reversible transition from glass-like state at low temperature to liquid-like state at high temperature in spore was revealed at the molecular level; (4) the kinetic processes of bacterial cell lysis of E. coli by lysozyme and by temperature induction of lambda phage were detected real-time; (5) the fixation and rehydration of human platelets were quantitatively evaluated and characterized with Raman spectroscopy method, which provided a rapid way to quantify the quality of freeze-dried therapeutic

  20. Learning From Experience: Qualitative Analysis to Develop a Cognitive Task List for Kielland Forceps Deliveries.

    PubMed

    Simpson, Andrea N; Hodges, Ryan; Snelgrove, John; Gurau, David; Secter, Michael; Mocarski, Eva; Pittini, Richard; Windrim, Rory; Higgins, Mary

    2015-05-01

    Objectif : La malposition fœtale constitue une indication courante menant à la tenue d’une césarienne au cours du deuxième stade du travail. Les forceps de Kielland sont un outil utile dans certaines situations pour assurer la réussite de l’accouchement vaginal; toutefois, les occasions d’en apprendre l’utilisation se font rares. Nous avions pour objectif d’identifier les composantes verbales et non verbales de la tenue en toute sûreté d’un accouchement au moyen de forceps de Kielland en filmant des démonstrations menées par des praticiens spécialisés sur des modèles, et ce, dans le but de rédiger une liste de tâches à des fins pédagogiques. Méthodes : Les infirmières du service d’obstétrique de trois hôpitaux universitaires ont identifié les cliniciens qu’elles considéraient comme étant compétents en ce qui concerne les accouchements par forceps de Kielland. Ces médecins ont consenti à l’entreprise et ont été filmés pendant l’exécution d’un accouchement par forceps de Kielland sur un modèle; pendant cette simulation, ils ont pris soin de décrire leur évaluation et leur technique, en plus de partager des conseils cliniques fondés sur leur expérience. Deux cliniciens ont passé en revue les vidéos de façon indépendante et ont consigné les composantes verbales et non verbales de l’évaluation; une analyse thématique a été menée et une liste de tâches de base a été élaborée. L’algorithme a été distribué aux participants afin d’assurer un consensus. Résultats : Onze cliniciens ont été identifiés; huit d’entre eux ont consenti à participer au projet. Les thèmes communs ont été la prévention de la malposition persistante (dans la mesure du possible), une évaluation exhaustive visant à déterminer la pertinence de la tenue d’un accouchement par forceps, les rôles de l’équipe multidisciplinaire, la description des forceps de Kielland et les aspects techniques associés

  1. How safe is gamete micromanipulation by laser tweezers?

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Tromberg, Bruce J.; Tadir, Yona; Berns, Michael W.

    1998-04-01

    Laser tweezers, used as novel sterile micromanipulation tools of living cells, are employed in laser-assisted in vitro fertilization (IVF). For example, controlled spermatozoa transport with 1064 nm tweezers to human egg cells has been performed in European clinics in cases of male infertility. The interaction of approximately 100 mW near infrared (NIR) trapping beams at MW/cm2 intensity with human gametes results in low mean less than 2 K temperature increases and less than 100 pN trapping forces. Therefore, photothermal or photomechanical induced destructive effects appear unlikely. However, the high photon flux densities may induce simultaneous absorption of two NIR photons resulting in nonlinear interactions. These nonlinear interactions imply non-resonant two-photon excitation of endogenous cellular chromophores. In the case of less than 800 nm tweezers, UV- like damage effects may occur. The destructive effect is amplified when multimode cw lasers are used as tweezer sources due to longitudinal mode-beating effects and partial mode- locking. Spermatozoa damage within seconds using 760 nm traps due to formation of unstable ps pulses in a cw Ti:Sa ring laser is demonstrated. We recommend the use of greater than or equal to 800 nm traps for optical gamete micromanipulation. To our opinion, further basic studies on the influence of nonlinear effects of laser tweezers on human gamete are necessary.

  2. Systems approach to identification of feedback enhanced optical tweezers

    NASA Astrophysics Data System (ADS)

    Sehgal, Hullas; Aggarwal, Tanuj; Salapaka, Murti V.

    2008-08-01

    Feedback enhanced optical tweezers, based on Proportional and Integral (PI) control, are routinely used for increasing the stiffness of optical traps. Digital implementation of PI controller, using DSP or FPGA, enables easy maneuverability of feedback gains. In this paper, we report occurrence of a peak in the thermal noise power spectrum of the trapped bead as the proportional gain is cranked up, which imposes a limit on how stiff a trap can be made using position feedback. We explain the reasons for the deviant behavior in the power spectrum and present a mathematical formula to account for the anomaly, which is in very good agreement with the experimental observations. Further, we present a new method to do the closed loop system identification of feedback enhanced optical tweezers by applying a frequency chirp. The system model thus obtained greatly predicts the closed loop behavior of our feedback based optical tweezers system.

  3. A Plasma Tweezer Concept to De-spin an Asteroid

    NASA Astrophysics Data System (ADS)

    Vereen, Keon; Datta, Iman; You, Setthivoine

    2014-10-01

    The Plasma Tweezer is a new concept for controlled de-spinning and deflection of space bodies without mechanical contact. The method shoots plasma jets or beams at the target from a pair of plasma thrusters located at the end of each lever arm of a ``tweezer'' structure. The main spacecraft body is at the fulcrum point of the tweezer and the target is located between the thrusters. This arrangement cancels out the impulse of two plasma jets on the spacecraft and applies forces on opposite sides of the target. Careful timing and orientation of the jets can then provide the necessary forces to despin and redirect the target. This concept is more efficient than the Ion Beam Shepherd method [C. Bombardelli and J. Pelaez, J. Guid. Control Dyn. (2011)] because it does not require a secondary thruster to cancel momentum and can benefit from angular momentum stored in the spacecraft's initial spin stabilization.

  4. Hook Region Represented in a Cochlear Model

    NASA Astrophysics Data System (ADS)

    Steele, Charles R.; Kim, Namkeun; Puria, Sunil

    2009-02-01

    The present interest is in discontinuities. Particularly the geometry of the hook region, with the flexible round window nearly parallel with the basilar membrane, is not represented by a standard box model, in which both stapes and round window are placed at the end. A better model represents the round window by a soft membrane in the wall of scala tympani, with the end closed. This complicates the analysis considerably. Features are that the significant compression wave, i.e., the fast wave, is of negligible magnitude in this region, and that significant evanescent waves occur because of the discontinuities at the beginning and end of the simulated round window. The effect of this on both high frequency, with maximum basilar membrane response in the hook region, and lower frequencies are determined.

  5. Magnetic tweezers for manipulation of magnetic particles in single cells

    NASA Astrophysics Data System (ADS)

    Ebrahimian, H.; Giesguth, M.; Dietz, K.-J.; Reiss, G.; Herth, S.

    2014-02-01

    Magnetic tweezers gain increasing interest for applications in biology. Here, a setup of magnetic tweezers is introduced using micropatterned conducting lines on transparent glass slides. Magnetic particles of 1 μm diameter were injected in barley cell vacuoles using a microinject system under microscopic control. Time dependent tracking of the particles after application of a magnetic field was used to determine the viscosity of vacuolar sap in vivo relative to water and isolated vacuolar fluid. The viscosity of vacuolar sap in cells was about 2-fold higher than that of extracted vacuolar fluid and 5 times higher than that of water.

  6. Control and manipulation of cold atoms in optical tweezers

    NASA Astrophysics Data System (ADS)

    Muldoon, Cecilia; Brandt, Lukas; Dong, Jian; Stuart, Dustin; Brainis, Edouard; Himsworth, Matthew; Kuhn, Axel

    2012-07-01

    Neutral atoms trapped by laser light are among the most promising candidates for storing and processing information in a quantum computer or simulator. The application certainly calls for a scalable and flexible scheme for addressing and manipulating the atoms. We have now made this a reality by implementing a fast and versatile method to dynamically control the position of neutral atoms trapped in optical tweezers. The tweezers result from a spatial light modulator (SLM) controlling and shaping a large number of optical dipole-force traps. Trapped atoms adapt to any change in the potential landscape, such that one can rearrange and randomly access individual sites within atom-trap arrays.

  7. Dynamic optical tweezers based assay for monitoring early drug resistance

    NASA Astrophysics Data System (ADS)

    Wu, Xiaojing; Zhang, Yuquan; Min, Changjun; Zhu, Siwei; Feng, Jie; Yuan, X.-C.

    2013-06-01

    In this letter, a dynamic optical tweezers based assay is proposed and investigated for monitoring early drug resistance with Pemetrexed-resistant non-small cell lung cancer (NSCLC) cell lines. The validity and stability of the method are verified experimentally in terms of the physical parameters of the optical tweezers system. The results demonstrate that the proposed technique is more convenient and faster than traditional techniques when the capability of detecting small variations of the response of cells to a drug is maintained.

  8. Tunable optical tweezers for wavelength-dependent measurements.

    PubMed

    Hester, Brooke; Campbell, Gretchen K; López-Mariscal, Carlos; Filgueira, Carly Levin; Huschka, Ryan; Halas, Naomi J; Helmerson, Kristian

    2012-04-01

    Optical trapping forces depend on the difference between the trap wavelength and the extinction resonances of trapped particles. This leads to a wavelength-dependent trapping force, which should allow for the optimization of optical tweezers systems, simply by choosing the best trapping wavelength for a given application. Here we present an optical tweezer system with wavelength tunability, for the study of resonance effects. With this system, the optical trap stiffness is measured for single trapped particles that exhibit either single or multiple extinction resonances. We include discussions of wavelength-dependent effects, such as changes in temperature, and how to measure them.

  9. Protective effect of policosanol on endothelium and intimal thickness induced by forceps in rabbits.

    PubMed

    Noa, Miríam; Más, Rosa; Lariot, Carlos

    2007-09-01

    Policosanol is a cholesterol-lowering drug isolated from sugar cane wax with concomitant antiplatelet effects that prevents lipofundin-induced atherosclerotic lesions in rabbits and rats, including foam cell formation, and also reduces foam cell formation in carrageenan-induced granulomas in rats, while it inhibits proliferation of smooth muscle cells induced in rabbit cuffed artery. This study was undertaken to determine whether policosanol prevents endothelium damage and increase in arterial wall thickness in rabbits with arterial walls damaged with a forceps. Artery forceps were placed over the central artery of the right ear of all rabbits, and each artery was injured eight times. Animals were randomly distributed into four groups: a positive control group treated with Tween 20/H2O vehicle, two groups treated with policosanol (5 and 25 mg/kg, respectively), and a group treated with aspirin (8 mg/kg). Treatments were given for 30 days. Damaged arteries were examined by light and electron (transmission and scanning) microscopy. To evaluate intimal thickening, areas of intima were measured, and a significant reduction in policosanol-treated animals was observed. The endothelial surface, studied with scanning electron microscopy, revealed several types of damage. In control group, the endothelial surface was severely damaged. De-endothelialized areas were reduced in policosanol-treated animals. Platelet adhesion to subendothelium was seen in all animals of the control group, whereas policosanol-treated groups exhibited significantly reduced platelet adhesion. Policosanol also reduced, dose-dependently, the platelet sequestration induced in the damaged vessel wall, partially preventing the reduction in platelet count. It is concluded that policosanol prevents endothelium injury and reduces significantly intimal thickness of rabbit arteries damaged with forceps.

  10. Optical tweezers reveal how proteins alter replication

    NASA Astrophysics Data System (ADS)

    Chaurasiya, Kathy

    Single molecule force spectroscopy is a powerful method that explores the DNA interaction properties of proteins involved in a wide range of fundamental biological processes such as DNA replication, transcription, and repair. We use optical tweezers to capture and stretch a single DNA molecule in the presence of proteins that bind DNA and alter its mechanical properties. We quantitatively characterize the DNA binding mechanisms of proteins in order to provide a detailed understanding of their function. In this work, we focus on proteins involved in replication of Escherichia coli (E. coli ), endogenous eukaryotic retrotransposons Ty3 and LINE-1, and human immunodeficiency virus (HIV). DNA polymerases replicate the entire genome of the cell, and bind both double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) during DNA replication. The replicative DNA polymerase in the widely-studied model system E. coli is the DNA polymerase III subunit alpha (DNA pol III alpha). We use optical tweezers to determine that UmuD, a protein that regulates bacterial mutagenesis through its interactions with DNA polymerases, specifically disrupts alpha binding to ssDNA. This suggests that UmuD removes alpha from its ssDNA template to allow DNA repair proteins access to the damaged DNA, and to facilitate exchange of the replicative polymerase for an error-prone translesion synthesis (TLS) polymerase that inserts nucleotides opposite the lesions, so that bacterial DNA replication may proceed. This work demonstrates a biophysical mechanism by which E. coli cells tolerate DNA damage. Retroviruses and retrotransposons reproduce by copying their RNA genome into the nuclear DNA of their eukaryotic hosts. Retroelements encode proteins called nucleic acid chaperones, which rearrange nucleic acid secondary structure and are therefore required for successful replication. The chaperone activity of these proteins requires strong binding affinity for both single- and double-stranded nucleic

  11. Assembling silver nanowires using optoelectronic tweezers

    NASA Astrophysics Data System (ADS)

    Zhang, Shuailong; Cooper, Jonathan M.; Neale, Steve L.

    2016-03-01

    Light patterned dielectrophoresis or optoelectronic tweezers (OET) has been proved to be an effective micromanipulation technology for cell separation, cell sorting and control of cell interactions. Apart from being useful for cell biology experiments, the capability of moving small objects accurately also makes OET an attractive technology for other micromanipulation applications. In particular, OET has the potential to be used for efficiently and accurately assembling small optoelectronic/electronic components into circuits. This approach could produce a step change in the size of the smallest components that are routinely assembled; down from the current smallest standard component size of 400×200 μm (0402 metric) to components a few microns across and even nanostructured components. In this work, we have demonstrated the use of OET to manipulate conductive silver nanowires into different patterns. The silver nanowires (typical diameter: 60 nm; typical length: 10 μm) were suspended in a 15 mS/m solution of KCL in water and manipulated by positive dielectrophoresis force generated by OET. A proof-of-concept demonstration was also made to prove the feasibility of using OET to manipulate silver nanowires to form a 150-μm-long conductive path between two isolated electrodes. It can be seen that the resistance between two electrodes was effectively brought down to around 700 Ω after the silver nanowires were assembled and the solution evaporated. Future work in this area will focus on increasing the conductivity of these tracks, encapsulating the assembled silver nanowires to prevent silver oxidation and provide mechanical protection, which can be achieved via 3D printing and inkjet printing technology.

  12. Airy acoustical-sheet spinner tweezers

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2016-09-01

    The Airy acoustical beam exhibits parabolic propagation and spatial acceleration, meaning that the propagation bending angle continuously increases before the beam trajectory reaches a critical angle where it decays after a propagation distance, without applying any external bending force. As such, it is of particular importance to investigate its properties from the standpoint of acoustical radiation force, spin torque, and particle dynamics theories, in the development of novel particle sorting techniques and acoustically mediated clearing systems. This work investigates these effects on a two-dimensional (2D) circular absorptive structure placed in the field of a nonparaxial Airy "acoustical-sheet" (i.e., finite beam in 2D), for potential applications in surface acoustic waves and acousto-fluidics. Based on the characteristics of the acoustic field, the beam is capable of manipulating the circular cylindrical fluid cross-section and guides it along a transverse or parabolic trajectory. This feature of Airy acoustical beams could lead to a unique characteristic in single-beam acoustical tweezers related to acoustical sieving, filtering, and removal of particles and cells from a section of a small channel. The analysis developed here is based on the description of the nonparaxial Airy beam using the angular spectrum decomposition of plane waves in close association with the partial-wave series expansion method in cylindrical coordinates. The numerical results demonstrate the ability of the nonparaxial Airy acoustical-sheet beam to pull, propel, or accelerate a particle along a parabolic trajectory, in addition to particle confinement in the transverse direction of wave propagation. Negative or positive radiation force and spin torque causing rotation in the clockwise or the anticlockwise direction can occur depending on the nondimensional parameter ka (where k is the wavenumber and a is the radius) and the location of the cylinder in the beam. Applications in

  13. Application of calibrated forceps for assessing mechanical nociception with high time resolution in mice

    PubMed Central

    Kashiwadani, Hideki; Kanmura, Yuichi; Kuwaki, Tomoyuki

    2017-01-01

    In order to investigate the basic physiological mechanisms of pain and the anti-nociceptive effects of analgesics, development of pain assays in mice is critical due to the advances of genetic manipulation techniques. The von Frey hairs/Semmes-Weinstein monofilaments test (von Frey test) has long been applied to examine mechanical nociception in mice. Though the von Frey test is a well-established and standardized method, it is inappropriate to assess a rapid change in the nociceptive threshold because voluntary resting/sleeping states are necessary to examine the response. In this study, we assessed the effectiveness of calibrated forceps to determine the mechanical nociceptive threshold in mice. Repeated daily measurements of the threshold over 5 days indicated that the device obtained stable and reliable values. Furthermore, repeated measurements with 5 minute intervals revealed that the device detected the rapid change of the threshold induced by remifentanil, a short-acting μ-receptor agonist. These results indicate that the calibrated forceps are well-suited for measuring the mechanical nociceptive threshold in mice, and are useful in assessing the effects of short-acting analgesics on mechanical nociception. PMID:28212389

  14. Development of Multi Degrees-of-Freedom Bilateral Forceps Robot System Using FPGA

    NASA Astrophysics Data System (ADS)

    Ishii, Ena; Katsura, Seiichiro; Nishi, Hiroaki; Ohnishi, Kouhei

    In recent days, minimally invasive surgery by using endoscope has spread and robots that support endoscopic surgery are being focused on. However, existing surgery robots could not transmit information of tactile sensation to operators. To improve the safety of robotic surgery, it is required to transmit the tactile sensation to the operator. To attain that need, a teleoperation method called bilateral has developed and we have achieved to transmit keen tactile sensation with one degree-of-freedom forceps robots. In this paper, multi degrees-of-freedom bilateral forceps robot system will be developed to make surgery robot adaptable to actual situation of the surgery. In bilateral teleoperation of multi degrees-of-freedom robots, environmental information of master and slave should be exchanged in common coordinates. In this paper, mode coordinates is used as common coordinates. Mode coordinates are closely related to the motion of the robot. Method to decouple the mechanical interference on mode coordinate is proposed. The paper also proposes a controller implemented on FPGA to achieve short processing time and hard-realtime control. As a result, multi-degrees-of freedom force feedback is attained. The experimental results show the viability of the proposed method.

  15. Using Forceps Biopsy after Small Submucosal Dissection in the Diagnosis of Gastric Subepithelial Tumors.

    PubMed

    Jung, Yoon Suk; Lee, Hyuk; Kim, Kyungeun; Sohn, Jin Hee; Kim, Hong Joo; Park, Jung Ho

    2016-11-01

    The current tissue sampling techniques for subepithelial tumors (SETs) of the gastrointestinal (GI) tract have limited diagnostic efficacy. We evaluated the diagnostic yield and safety of forceps biopsies after small endoscopic submucosal dissection (SESD biopsies) in the diagnosis of gastric SETs. A total of 42 patients with gastric SETs > 10 mm were prospectively enrolled between May 2013 and October 2014. A dual knife was used to incise the mucosa and submucosa and forceps biopsies were then introduced deep into the lesion. To compare SESD biopsies with EUS-FNA, we used the retrospective data of 30 EUS-FNA cases. The diagnostic yield of SESD biopsies was comparable to that of EUS-FNA (35/42, 83.3% vs. 24/30, 80.0%, P = 0.717). The mean procedure time of SESD biopsies was shorter than that of EUS-FNA (10 vs. 37 minutes, P < 0.001). There were no procedure-related adverse events in the both group. The pathological diagnoses in SESD biopsies group included 15 leiomyomas, 7 GISTs, 10 heterotopic pancreases, 2 lipomas, and one other lesion. SESD biopsies are an easy, effective and safe technique for the diagnosis of gastric SETs and its diagnostic yield is comparable to that of EUS-FNA. This technique may be a reliable alternative to conventional EUS-FNA (Clinical trial registration No. KCT0000730).

  16. Using Forceps Biopsy after Small Submucosal Dissection in the Diagnosis of Gastric Subepithelial Tumors

    PubMed Central

    2016-01-01

    The current tissue sampling techniques for subepithelial tumors (SETs) of the gastrointestinal (GI) tract have limited diagnostic efficacy. We evaluated the diagnostic yield and safety of forceps biopsies after small endoscopic submucosal dissection (SESD biopsies) in the diagnosis of gastric SETs. A total of 42 patients with gastric SETs > 10 mm were prospectively enrolled between May 2013 and October 2014. A dual knife was used to incise the mucosa and submucosa and forceps biopsies were then introduced deep into the lesion. To compare SESD biopsies with EUS-FNA, we used the retrospective data of 30 EUS-FNA cases. The diagnostic yield of SESD biopsies was comparable to that of EUS-FNA (35/42, 83.3% vs. 24/30, 80.0%, P = 0.717). The mean procedure time of SESD biopsies was shorter than that of EUS-FNA (10 vs. 37 minutes, P < 0.001). There were no procedure-related adverse events in the both group. The pathological diagnoses in SESD biopsies group included 15 leiomyomas, 7 GISTs, 10 heterotopic pancreases, 2 lipomas, and one other lesion. SESD biopsies are an easy, effective and safe technique for the diagnosis of gastric SETs and its diagnostic yield is comparable to that of EUS-FNA. This technique may be a reliable alternative to conventional EUS-FNA (Clinical trial registration No. KCT0000730). PMID:27709855

  17. Trapping and patterning of biological objects using photovoltaic tweezers

    NASA Astrophysics Data System (ADS)

    Jubera, M.; Elvira, I.; García-Cabañes, A.; Bella, J. L.; Carrascosa, M.

    2016-01-01

    Photovoltaic tweezers are a recently proposed technique for manipulation and patterning of micro- and nano-objects. It is based in the dielectrophoretic forces associated to the electric fields induced by illumination of certain ferroelectrics due to the bulk photovoltaic effect. The technique has been applied to the patterning of dielectric and metal micro- and nano-particles. In this work, we report the use of photovoltaic tweezers to pattern biological objects on LiNbO3:Fe. Specifically, spores and pollen grains and their nanometric fragments have been trapped and patterned. 1D and 2D arrangements have been achieved by deposition in air or from a hexane suspension. The quality of patterns obtained with nanometric fragments is even better than previous results using photovoltaic tweezers with inorganic micro- and nano-particles. In fact, 1D patterns with a period of 2 μm, almost half of the minimum reported period achieved with photovoltaic tweezers, have been obtained with pollen fragments.

  18. Ultrahigh Frequency Lensless Ultrasonic Transducers for Acoustic Tweezers Application

    PubMed Central

    Hsu, Hsiu-Sheng; Li, Ying; Lee, Changyang; Lin, Anderson; Zhou, Qifa; Kim, Eun Sok; Shung, Kirk Koping

    2014-01-01

    Similar to optical tweezers, a tightly focused ultrasound microbeam is needed to manipulate microparticles in acoustic tweezers. The development of highly sensitive ultrahigh frequency ultrasonic transducers is crucial for trapping particles or cells with a size of a few microns. As an extra lens would cause excessive attenuation at ultrahigh frequencies, two types of 200-MHz lensless transducer design were developed as an ultrasound microbeam device for acoustic tweezers application. Lithium niobate single crystal press-focused (PF) transducer and zinc oxide self-focused transducer were designed, fabricated and characterized. Tightly focused acoustic beams produced by these transducers were shown to be capable of manipulating single microspheres as small as 5 μm two-dimensionally within a range of hundreds of micrometers in distilled water. The size of the trapped microspheres is the smallest ever reported in the literature of acoustic PF devices. These results suggest that these lensless ultrahigh frequency ultrasonic transducers are capable of manipulating particles at the cellular level and that acoustic tweezers may be a useful tool to manipulate a single cell or molecule for a wide range of biomedical applications. PMID:23042219

  19. Spin dynamics and Kondo physics in optical tweezers

    NASA Astrophysics Data System (ADS)

    Lin, Yiheng; Lester, Brian J.; Brown, Mark O.; Kaufman, Adam M.; Long, Junling; Ball, Randall J.; Isaev, Leonid; Wall, Michael L.; Rey, Ana Maria; Regal, Cindy A.

    2016-05-01

    We propose to use optical tweezers as a toolset for direct observation of the interplay between quantum statistics, kinetic energy and interactions, and thus implement minimum instances of the Kondo lattice model in systems with few bosonic rubidium atoms. By taking advantage of strong local exchange interactions, our ability to tune the spin-dependent potential shifts between the two wells and complete control over spin and motional degrees of freedom, we design an adiabatic tunneling scheme that efficiently creates a spin-singlet state in one well starting from two initially separated atoms (one atom per tweezer) in opposite spin state. For three atoms in a double-well, two localized in the lowest vibrational mode of each tweezer and one atom in an excited delocalized state, we plan to use similar techniques and observe resonant transfer of two-atom singlet-triplet states between the wells in the regime when the exchange coupling exceeds the mobile atom hopping. Moreover, we argue that such three-atom double-tweezers could potentially be used for quantum computation by encoding logical qubits in collective spin and motional degrees of freedom. Current address: Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.

  20. Plasmon enhanced optical tweezers with gold-coated black silicon

    NASA Astrophysics Data System (ADS)

    Kotsifaki, D. G.; Kandyla, M.; Lagoudakis, P. G.

    2016-05-01

    Plasmonic optical tweezers are a ubiquitous tool for the precise manipulation of nanoparticles and biomolecules at low photon flux, while femtosecond-laser optical tweezers can probe the nonlinear optical properties of the trapped species with applications in biological diagnostics. In order to adopt plasmonic optical tweezers in real-world applications, it is essential to develop large-scale fabrication processes without compromising the trapping efficiency. Here, we develop a novel platform for continuous wave (CW) and femtosecond plasmonic optical tweezers, based on gold-coated black silicon. In contrast with traditional lithographic methods, the fabrication method relies on simple, single-step, maskless tabletop laser processing of silicon in water that facilitates scalability. Gold-coated black silicon supports repeatable trapping efficiencies comparable to the highest ones reported to date. From a more fundamental aspect, a plasmon-mediated efficiency enhancement is a resonant effect, and therefore, dependent on the wavelength of the trapping beam. Surprisingly, a wavelength characterization of plasmon-enhanced trapping efficiencies has evaded the literature. Here, we exploit the repeatability of the recorded trapping efficiency, offered by the gold-coated black silicon platform, and perform a wavelength-dependent characterization of the trapping process, revealing the resonant character of the trapping efficiency maxima. Gold-coated black silicon is a promising platform for large-scale parallel trapping applications that will broaden the range of optical manipulation in nanoengineering, biology, and the study of collective biophotonic effects.

  1. Plasmon enhanced optical tweezers with gold-coated black silicon

    PubMed Central

    Kotsifaki, D. G.; Kandyla, M.; Lagoudakis, P. G.

    2016-01-01

    Plasmonic optical tweezers are a ubiquitous tool for the precise manipulation of nanoparticles and biomolecules at low photon flux, while femtosecond-laser optical tweezers can probe the nonlinear optical properties of the trapped species with applications in biological diagnostics. In order to adopt plasmonic optical tweezers in real-world applications, it is essential to develop large-scale fabrication processes without compromising the trapping efficiency. Here, we develop a novel platform for continuous wave (CW) and femtosecond plasmonic optical tweezers, based on gold-coated black silicon. In contrast with traditional lithographic methods, the fabrication method relies on simple, single-step, maskless tabletop laser processing of silicon in water that facilitates scalability. Gold-coated black silicon supports repeatable trapping efficiencies comparable to the highest ones reported to date. From a more fundamental aspect, a plasmon-mediated efficiency enhancement is a resonant effect, and therefore, dependent on the wavelength of the trapping beam. Surprisingly, a wavelength characterization of plasmon-enhanced trapping efficiencies has evaded the literature. Here, we exploit the repeatability of the recorded trapping efficiency, offered by the gold-coated black silicon platform, and perform a wavelength-dependent characterization of the trapping process, revealing the resonant character of the trapping efficiency maxima. Gold-coated black silicon is a promising platform for large-scale parallel trapping applications that will broaden the range of optical manipulation in nanoengineering, biology, and the study of collective biophotonic effects. PMID:27195446

  2. Multipoint viscosity measurements in microfluidic channels using optical tweezers.

    PubMed

    Keen, Stephen; Yao, Alison; Leach, Jonathan; Di Leonardo, Roberto; Saunter, Chris; Love, Gordon; Cooper, Jonathan; Padgett, Miles

    2009-07-21

    We demonstrate the technique of multipoint viscosity measurements incorporating the accurate calibration of micron sized particles. We describe the use of a high-speed camera to measure the residual motion of particles trapped in holographic optical tweezers, enabling us to calculate the fluid viscosity at multiple points across the field-of-view of the microscope within a microfluidic system.

  3. Successful Treatment of Carcinomatous Central Airway Obstruction with Bronchoscopic Electrocautery Using Hot Biopsy Forceps during Mechanical Ventilation.

    PubMed

    Ugajin, Motoi; Kani, Hisanori

    2017-01-01

    We report the case of a 72-year-old man with occlusion of the left main bronchus due to squamous cell carcinoma of the lung. He required tracheal intubation and mechanical ventilation because of the aggravation of atelectasis and obstructive pneumonia. Electrocautery using hot biopsy forceps was performed during mechanical ventilation with a 40% fraction of inspired oxygen. He was extubated following improvement in the atelectasis and obstructive pneumonia and discharged with shrinkage of the tumor after chemotherapy. We describe a safe electrocautery procedure using hot biopsy forceps during mechanical ventilation with reference to previous reports.

  4. Successful Treatment of Carcinomatous Central Airway Obstruction with Bronchoscopic Electrocautery Using Hot Biopsy Forceps during Mechanical Ventilation

    PubMed Central

    Kani, Hisanori

    2017-01-01

    We report the case of a 72-year-old man with occlusion of the left main bronchus due to squamous cell carcinoma of the lung. He required tracheal intubation and mechanical ventilation because of the aggravation of atelectasis and obstructive pneumonia. Electrocautery using hot biopsy forceps was performed during mechanical ventilation with a 40% fraction of inspired oxygen. He was extubated following improvement in the atelectasis and obstructive pneumonia and discharged with shrinkage of the tumor after chemotherapy. We describe a safe electrocautery procedure using hot biopsy forceps during mechanical ventilation with reference to previous reports. PMID:28373918

  5. Unraveling chromatin structure using magnetic tweezers

    NASA Astrophysics Data System (ADS)

    van Noort, John

    2010-03-01

    The compact, yet dynamic organization of chromatin plays an essential role in regulating gene expression. Although the static structure of chromatin fibers has been studied extensively, the controversy about the higher order folding remains. The compaction of eukaryotic DNA into chromatin has been implicated in the regulation of all DNA processes. To understand the relation between gene regulation and chromatin structure it is essential to uncover the mechanisms by which chromatin fibers fold and unfold. We used magnetic tweezers to probe the mechanical properties of individual nucleosomes and chromatin fibers consisting of a single, well-defined array of 25 nucleosomes. From these studies five major features appeared upon forced extension of chromatin fibers: the elastic stretching of chromatin's higher order structure, the breaking of internucleosomal contacts, unwrapping of the first turn of DNA, unwrapping of the second turn of DNA, and the dissociation of histone octamers. These events occur sequentially at the increasing force. Neighboring nucleosomes stabilize DNA folding into a nucleosome relative to isolated nucleosomes. When an array of nucleosomes is folded into a 30 nm fiber, representing the first level of chromatin condensation, the fiber stretched like a Hookian spring at forces up to 4 pN. Together with a nucleosome-nucleosome stacking energy of 14 kT this points to a solenoid as the underlying topology of the 30 nm fiber. Surprisingly, linker histones do not affect the length or stiffness of the fibers, but stabilize fiber folding up to forces of 7 pN. The stiffness of the folded chromatin fiber points at histone tails that mediate nucleosome stacking. Fibers with a nucleosome repeat length of 167 bp instead of 197 bp are significantly stiffer, consistent with a two-start helical arrangement. The extensive thermal breathing of the chromatin fiber that is a consequence of the observed high compliance provides a structural basis for understanding the

  6. Development and biological applications of optical tweezers and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Xie, Chang'an

    Optical tweezers is a three-dimensional manipulation tool that employs a gradient force that originates from the single highly focused laser beam. Raman spectroscopy is a molecular analytical tool that can give a highly unique "fingerprint" for each substance by measuring the unique vibrations of its molecules. The combination of these two optical techniques offers a new tool for the manipulation and identification of single biological cells and microscopic particles. In this thesis, we designed and implemented a Laser-Tweezers-Raman-Spectroscopy (LTRS) system, also called the Raman-tweezers, for the simultaneous capture and analysis of both biological particles and non-biological particles. We show that microparticles can be conveniently captured at the focus of a laser beam and the Raman spectra of trapped particles can be acquired with high quality. The LTRS system overcomes the intrinsic Brownian motion and cell motility of microparticles in solution and provides a promising tool for in situ identifying suspicious agents. In order to increase the signal to noise ratio, several schemes were employed in LTRS system to reduce the blank noise and the fluorescence signal coming from analytes and the surrounding background. These techniques include near-infrared excitation, optical levitation, confocal microscopy, and frequency-shifted Raman difference. The LTRS system has been applied for the study in cell biology at the single cell level. With the built Raman-tweezers system, we studied the dynamic physiological processes of single living cells, including cell cycle, the transcription and translation of recombinant protein in transgenic yeast cells and the T cell activation. We also studied cell damage and associated biochemical processes in optical traps, UV radiations, and evaluated heating by near-infrared Raman spectroscopy. These studies show that the Raman-tweezers system is feasible to provide rapid and reliable diagnosis of cellular disorders and can be

  7. Hook nozzle arrangement for supporting airfoil vanes

    DOEpatents

    Shaffer, James E.; Norton, Paul F.

    1996-01-01

    A gas turbine engine's nozzle structure includes a nozzle support ring, a plurality of shroud segments, and a plurality of airfoil vanes. The plurality of shroud segments are distributed around the nozzle support ring. Each airfoil vane is connected to a corresponding shroud segment so that the airfoil vanes are also distributed around the nozzle support ring. Each shroud segment has a hook engaging the nozzle support ring so that the shroud segments and corresponding airfoil vanes are supported by the nozzle support ring. The nozzle support ring, the shroud segments, and the airfoil vanes may be ceramic.

  8. 29 CFR 1915.113 - Shackles and hooks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... tests, the signature of the person who performed the test and an identifier for the hook which was... and Materials Handling § 1915.113 Shackles and hooks. The provisions of this section shall apply to... recommendations shall be followed in determining the safe working loads of the various sizes and types of...

  9. Personality as a predictor of hooking up among college students.

    PubMed

    Gute, Gary; Eshbaugh, Elaine M

    2008-01-01

    Hookups--casual sexual encounters that may or may not include intercourse - are common on college campuses. Previous research has suggested that these casual sexual encounters may have serious health-related consequences. Understanding the relationships among multiple predictors of hooking up is important if high-risk prevention programming among college students is to be effective. This study considers each of the Big Five personality traits as predictors of hooking-up behaviors in a sample of Midwestern undergraduates (N = 247). Fifty-six percent of women and 63% of men reported engaging in a hookup. In general, Extraversion was positively associated with hooking up behaviors; Conscientiousness was negatively associated with hooking up. Relationships between personality and hooking up were significant while controlling for alcohol use. Implications for prevention programming on college campuses are discussed.

  10. Endoscopic ultrasound-guided forceps biopsy from upper gastrointestinal subepithelial lesions using a forward-viewing echoendoscope

    PubMed Central

    Matsuzaki, Ippei; Miyahara, Ryoji; Hirooka, Yoshiki; Funasaka, Kohei; Yamamura, Takeshi; Ohno, Eizaburo; Nakamura, Masanao; Kawashima, Hiroki; Watanabe, Osamu; Kobayashi, Makoto; Shimoyama, Yoshie; Nakamura, Shigeo; Goto, Hidemi

    2016-01-01

    Background and study aims: Endoscopic tissue acquisition techniques using needle-knife and biopsy forceps allow abundant tissue acquisition from upper gastrointestinal subepithelial lesions; however, these techniques cannot capture real-time intratumor information. The aim of this study was to evaluate the feasibility of endoscopic ultrasound-guided forceps biopsy (EUS-FB) from upper gastrointestinal subepithelial lesions using a forward-viewing echoendoscope. Patients and methods: This study was a prospective case series. After mucosal cuts, several specimens were taken using a hot biopsy forceps under real-time EUS visualization. The incision was closed using hemoclips. Diagnostic yield, rate of diagnosable samples obtained under EUS visualization, procedure time, and adverse events were assessed. Results: Ten patients (median lesion size 16 mm, range 15 – 44 mm) underwent EUS-FB. The overall rate of histological diagnosis by EUS-FB was 100 % (10/10). The rate of diagnosable samples among all cases was 97.6 % (41/42). The median procedure times for EUS-FB and complete closure were 28.5 and 4.5 minutes, respectively. No adverse events occurred. Conclusions: This newly developed EUS-FB is feasible and allowed forceps biopsy from upper gastrointestinal subepithelial lesions. Study registration: UMIN000015364 PMID:27556070

  11. Single-sided lateral-field and phototransistor-based optoelectronic tweezers

    NASA Technical Reports Server (NTRS)

    Ohta, Aaron (Inventor); Chiou, Pei-Yu (Inventor); Hsu, Hsan-Yin (Inventor); Jamshidi, Arash (Inventor); Wu, Ming-Chiang (Inventor); Neale, Steven L. (Inventor)

    2011-01-01

    Described herein are single-sided lateral-field optoelectronic tweezers (LOET) devices which use photosensitive electrode arrays to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the device. In addition, phototransistor-based optoelectronic tweezers (PhOET) devices are described that allow for optoelectronic tweezers (OET) operation in high-conductivity physiological buffer and cell culture media.

  12. Simultaneous calibration of optical tweezers spring constant and position detector response.

    PubMed

    Le Gall, Antoine; Perronet, Karen; Dulin, David; Villing, André; Bouyer, Philippe; Visscher, Koen; Westbrook, Nathalie

    2010-12-06

    We demonstrate a fast and direct calibration method for systems using a single laser for optical tweezers and particle position detection. The method takes direct advantage of back-focal-plane interferometry measuring not an absolute but a differential position, i.e. the position of the trapped particle relative to the center of the optical tweezers. Therefore, a fast step-wise motion of the optical tweezers yields the impulse response of the trapped particle. Calibration parameters such as the detector's spatial and temporal response and the spring constant of the optical tweezers then follow readily from fitting the measured impulse response.

  13. Nanoscopy of bacterial cells immobilized by holographic optical tweezers

    PubMed Central

    Diekmann, Robin; Wolfson, Deanna L.; Spahn, Christoph; Heilemann, Mike; Schüttpelz, Mark; Huser, Thomas

    2016-01-01

    Imaging non-adherent cells by super-resolution far-field fluorescence microscopy is currently not possible because of their rapid movement while in suspension. Holographic optical tweezers (HOTs) enable the ability to freely control the number and position of optical traps, thus facilitating the unrestricted manipulation of cells in a volume around the focal plane. Here we show that immobilizing non-adherent cells by optical tweezers is sufficient to achieve optical resolution well below the diffraction limit using localization microscopy. Individual cells can be oriented arbitrarily but preferably either horizontally or vertically relative to the microscope's image plane, enabling access to sample sections that are impossible to achieve with conventional sample preparation and immobilization. This opens up new opportunities to super-resolve the nanoscale organization of chromosomal DNA in individual bacterial cells. PMID:27958271

  14. Probing DNA with micro- and nanocapillaries and optical tweezers

    NASA Astrophysics Data System (ADS)

    Steinbock, L. J.; Otto, O.; Skarstam, D. R.; Jahn, S.; Chimerel, C.; Gornall, J. L.; Keyser, U. F.

    2010-11-01

    We combine for the first time optical tweezer experiments with the resistive pulse technique based on capillaries. Quartz glass capillaries are pulled into a conical shape with tip diameters as small as 27 nm. Here, we discuss the translocation of λ-phage DNA which is driven by an electrophoretic force through the nanocapillary. The resulting change in ionic current indicates the folding state of single λ-phage DNA molecules. Our flow cell design allows for the straightforward incorporation of optical tweezers. We show that a DNA molecule attached to an optically trapped colloid is pulled into a capillary by electrophoretic forces. The detected electrophoretic force is in good agreement with measurements in solid-state nanopores.

  15. Synthesis and Characterization of Carbazole-Linked Porphyrin Tweezers.

    PubMed

    Chang, Yi; Michelin, Clément; Bucher, Léo; Desbois, Nicolas; Gros, Claude P; Piant, Sébastien; Bolze, Frédéric; Fang, Yuanyuan; Jiang, Xiaoqin; Kadish, Karl M

    2015-08-17

    Herein the synthesis, spectroscopic characterization, two-photon absorption and electrochemical properties of 3,6-disubstituted carbazole tweezers is reported. A dimer resulting from a Glaser homocoupling was isolated during a Sonogashira coupling reaction between a diethynyl-carbazole spacer and a 5-bromo-triarylporphyrin and the properties of this original compound were compared with the 3,6-disubstituted carbazole bisporphyrin tweezers. The dyads reported herein present a two-photon absorption maximum at 920 nm with two-photon absorption cross-section in the 1200 GM range. Despite a strong linear absorption in the Soret region and moderate fluorescence quantum yield, they both lead to a high brightness reaching 30 000 M(-1)  cm(-1) .

  16. A guide to magnetic tweezers and their applications

    NASA Astrophysics Data System (ADS)

    Sarkar, Rupa; Rybenkov, Valentin

    2016-12-01

    Magnetic force spectroscopy is a rapidly developing single molecule technique that found numerous applications at the interface of physics and biology. Since the invention of the first magnetic tweezers, a number of modifications were incorporated into the approach that helped relieve the limitations of the original design and amplified its strengths. Inventive molecular biology solutions further advanced the technique by expanding its possible applications. In its present form, the method can be applied to single molecules and live cells without resorting to intense sample irradiation, can be easily multiplexed, accommodates multiple DNAs, displays impressive resolution, and allows a remarkable ease in stretching and twisting macromolecules. In this review, we describe the architecture of magnetic tweezers, key requirements to the experimental design and analysis of data, and outline several applications of the method that illustrate its versatility.

  17. A microscopic steam engine implemented in an optical tweezer

    NASA Astrophysics Data System (ADS)

    Quinto-Su, Pedro A.

    2014-12-01

    The introduction of improved steam engines at the end of the 18th century marked the start of the industrial revolution and the birth of classical thermodynamics. Currently, there is great interest in miniaturizing heat engines, but so far traditional heat engines operating with the expansion and compression of gas have not reached length scales shorter than one millimeter. Here, a micrometer-sized piston steam engine is implemented in an optical tweezer. The piston is a single colloidal microparticle that is driven by explosive vapourization of the surrounding liquid (cavitation bubbles) and by optical forces at a rate between a few tens of Hertz and one kilo-Hertz. The operation of the engine allows to exert impulsive forces with optical tweezers and induce streaming in the liquid, similar to the effect of transducers when driven at acoustic and ultrasound frequencies.

  18. A microscopic steam engine implemented in an optical tweezer.

    PubMed

    Quinto-Su, Pedro A

    2014-12-19

    The introduction of improved steam engines at the end of the 18th century marked the start of the industrial revolution and the birth of classical thermodynamics. Currently, there is great interest in miniaturizing heat engines, but so far traditional heat engines operating with the expansion and compression of gas have not reached length scales shorter than one millimeter. Here, a micrometer-sized piston steam engine is implemented in an optical tweezer. The piston is a single colloidal microparticle that is driven by explosive vapourization of the surrounding liquid (cavitation bubbles) and by optical forces at a rate between a few tens of Hertz and one kilo-Hertz. The operation of the engine allows to exert impulsive forces with optical tweezers and induce streaming in the liquid, similar to the effect of transducers when driven at acoustic and ultrasound frequencies.

  19. Determination of motility forces on isolated chromosomes with laser tweezers.

    PubMed

    Khatibzadeh, Nima; Stilgoe, Alexander B; Bui, Ann A M; Rocha, Yesenia; Cruz, Gladys M; Loke, Vince; Shi, Linda Z; Nieminen, Timo A; Rubinsztein-Dunlop, Halina; Berns, Michael W

    2014-10-31

    Quantitative determination of the motility forces of chromosomes during cell division is fundamental to understanding a process that is universal among eukaryotic organisms. Using an optical tweezers system, isolated mammalian chromosomes were held in a 1064 nm laser trap. The minimum force required to move a single chromosome was determined to be ≈ 0.8-5 pN. The maximum transverse trapping efficiency of the isolated chromosomes was calculated as ≈ 0.01-0.02. These results confirm theoretical force calculations of ≈ 0.1-12 pN to move a chromosome on the mitotic or meiotic spindle. The verification of these results was carried out by calibration of the optical tweezers when trapping microspheres with a diameter of 4.5-15 µm in media with 1-7 cP viscosity. The results of the chromosome and microsphere trapping experiments agree with optical models developed to simulate trapping of cylindrical and spherical specimens.

  20. Mechanical force characterization in manipulating live cells with optical tweezers.

    PubMed

    Wu, Yanhua; Sun, Dong; Huang, Wenhao

    2011-02-24

    Laser trapping with optical tweezers is a noninvasive manipulation technique and has received increasing attentions in biological applications. Understanding forces exerted on live cells is essential to cell biomechanical characterizations. Traditional numerical or experimental force measurement assumes live cells as ideal objects, ignoring their complicated inner structures and rough membranes. In this paper, we propose a new experimental method to calibrate the trapping and drag forces acted on live cells. Binding a micro polystyrene sphere to a live cell and moving the mixture with optical tweezers, we can obtain the drag force on the cell by subtracting the drag force on the sphere from the total drag force on the mixture, under the condition of extremely low Reynolds number. The trapping force on the cell is then obtained from the drag force when the cell is in force equilibrium state. Experiments on numerous live cells demonstrate the effectiveness of the proposed force calibration approach.

  1. Sensing interactions in the microworld with optical tweezers

    NASA Astrophysics Data System (ADS)

    Pacoret, Cécile; Bowman, Richard; Gibson, Graham; Sinan, Haliyo D.; Bergander, Arvid; Carberry, David; Régnier, Stéphane; Padgett, Miles

    2009-08-01

    Optical Tweezers have become a widespread tool in Cell Biology, microengineering and other fields requiring delicate micromanipulation. But for those sensitive tasks, it remains difficult to handle objects without damaging them. As the precision in position and force measurement increase, the richness of information cannot be fully exploited with simple interfaces such as a mouse or a common joystick. For this reason, we propose a haptic force-feedback optical tweezer command and a force-feedback system controlled by one hand. The system combines accurate force measurement using a fast camera and the coupling of these measured forces with a human operator. The overall transparency allows even the feeling of the Brownian motion.

  2. Active-passive calibration of optical tweezers in viscoelastic media.

    PubMed

    Fischer, Mario; Richardson, Andrew C; Reihani, S Nader S; Oddershede, Lene B; Berg-Sørensen, Kirstine

    2010-01-01

    In order to use optical tweezers as a force measuring tool inside a viscoelastic medium such as the cytoplasm of a living cell, it is crucial to perform an exact force calibration within the complex medium. This is a nontrivial task, as many of the physical characteristics of the medium and probe, e.g., viscosity, elasticity, shape, and density, are often unknown. Here, we suggest how to calibrate single beam optical tweezers in a complex viscoelastic environment. At the same time, we determine viscoelastic characteristics such as friction retardation spectrum and elastic moduli of the medium. We apply and test a method suggested [M. Fischer and K. Berg-Sørensen, J. Opt. A, Pure Appl. Opt. 9, S239 (2007)], a method which combines passive and active measurements. The method is demonstrated in a simple viscous medium, water, and in a solution of entangled F-actin without cross-linkers.

  3. A Hooke׳s law-based approach to protein folding rate.

    PubMed

    Ruiz-Blanco, Yasser B; Marrero-Ponce, Yovani; Prieto, Pablo J; Salgado, Jesús; García, Yamila; Sotomayor-Torres, Clivia M

    2015-01-07

    Kinetics is a key aspect of the renowned protein folding problem. Here, we propose a comprehensive approach to folding kinetics where a polypeptide chain is assumed to behave as an elastic material described by the Hooke׳s law. A novel parameter called elastic-folding constant results from our model and is suggested to distinguish between protein with two-state and multi-state folding pathways. A contact-free descriptor, named folding degree, is introduced as a suitable structural feature to study protein-folding kinetics. This approach generalizes the observed correlations between varieties of structural descriptors with the folding rate constant. Additionally several comparisons among structural classes and folding mechanisms were carried out showing the good performance of our model with proteins of different types. The present model constitutes a simple rationale for the structural and energetic factors involved in protein folding kinetics.

  4. Multispectral optical tweezers for molecular diagnostics of single biological cells

    NASA Astrophysics Data System (ADS)

    Butler, Corey; Fardad, Shima; Sincore, Alex; Vangheluwe, Marie; Baudelet, Matthieu; Richardson, Martin

    2012-03-01

    Optical trapping of single biological cells has become an established technique for controlling and studying fundamental behavior of single cells with their environment without having "many-body" interference. The development of such an instrument for optical diagnostics (including Raman and fluorescence for molecular diagnostics) via laser spectroscopy with either the "trapping" beam or secondary beams is still in progress. This paper shows the development of modular multi-spectral imaging optical tweezers combining Raman and Fluorescence diagnostics of biological cells.

  5. Structural insights into bacterial flagellar hooks similarities and specificities

    PubMed Central

    Yoon, Young-Ho; Barker, Clive S.; Bulieris, Paula V.; Matsunami, Hideyuki; Samatey, Fadel A.

    2016-01-01

    Across bacteria, the protein that makes the flagellar hook, FlgE, has a high variability in amino acid residue composition and sequence length. We hereby present the structure of two fragments of FlgE protein from Campylobacter jejuni and from Caulobacter crescentus, which were obtained by X-ray crystallography, and a high-resolution model of the hook from Caulobacter. By comparing these new structures of FlgE proteins, we show that bacterial hook can be divided in two distinct parts. The first part comprises domains that are found in all FlgE proteins and that will make the basic structure of the hook that is common to all flagellated bacteria. The second part, hyper-variable both in size and structure, will be bacteria dependent. To have a better understanding of the C. jejuni hook, we show that a special strain of Salmonella enterica, which was designed to encode a gene of flgE that has the extra domains found in FlgE from C. jejuni, is fully motile. It seems that no matter the size of the hook protein, the hook will always have a structure made of 11 protofilaments. PMID:27759043

  6. Hooked: Habits of the Chinese Permian gigantopterid Gigantonoclea

    NASA Astrophysics Data System (ADS)

    Seyfullah, Leyla J.; Glasspool, Ian J.; Hilton, Jason

    2014-04-01

    Based upon anatomical evidence, Permian aged gigantopterid fossils are in general reconstructed as climbing or scrambling plants. Gigantonoclea, a genus of adpressed gigantopterid foliage from the Permian of northern China, has been reported to co-occur with hook-like organs that were interpreted as indicating a scrambling/climbing habit. We reinvestigated these hook-like structures and re-evaluated the nature of the co-occurrences in context with the flora preserved in each plant-bearing fossil 'bed' in the North China sedimentary succession. New findings show that the species Gigantonoclea hallei probably climbed using specially adapted clusters of compound grappling hook-like shoots borne on the stems. This structural arrangement comprising shoots of hooks is new to the scrambling/climbing concept in gigantopterids. However, a key figured specimen previously reported as showing intermediate hook-tipped leaf morphology on a sole pinnule tip is discounted as such and is reinterpreted as a 'normal' pinnule partially hidden under sediment that results in an unusual appearance to this pinnule tip. Adaptations for climbing or scrambling based upon 'hooked leaves' observed in Gigantonoclea lagrelii are no longer supported and are reinterpreted as incompletely expanded leaves where the vernation process was interrupted. These data weaken prior interpretations of G. lagrelii as a climber/scrambler and raise doubts about the ubiquity of hooks amongst the gigantopterids as structures enabling them to climb or scramble their way through the Permian world.

  7. Measurement of angular momentum flux in optical tweezers

    NASA Astrophysics Data System (ADS)

    Rubinsztein-Dunlop, Halina; Asavei, Theodor; Preece, Daryl; Stilgoe, Alexander B.; Heckenberg, Norman R.; Nieminen, Timo A.

    2011-03-01

    It is well established that a light beam can carry angular momentum and therefore when using optical tweezers it is possible to exert torques to twist or rotate microscopic objects. Both spin and orbital angular momentum can be transferred. This transfer can be achieved using birefringent particles exposed to a Gaussian circularly polarized beam. In this case, a transfer of spin angular momentum will occur. The change in spin, and hence the torque, can be readily measured optically. On the other hand, it is much more challenging to measure orbital angular momentum and torque. Laguerre-Gauss mode decomposition, as used for orbital angular momentum encoding for quantum communication, and rotational frequency shift can be used, and are effective methods in a macro-environment. However, the situation becomes more complicated when a measurement is done on microscale, especially with highly focused laser beams. We review the methods for the measurement of the angular momentum of light in optical tweezers, and the challenges faced when measuring orbital angular momentum. We also demonstrate one possible simple method for a quantitative measurement of the orbital angular momentum in optical tweezers.

  8. Magnetic tweezers: micromanipulation and force measurement at the molecular level.

    PubMed Central

    Gosse, Charlie; Croquette, Vincent

    2002-01-01

    Cantilevers and optical tweezers are widely used for micromanipulating cells or biomolecules for measuring their mechanical properties. However, they do not allow easy rotary motion and can sometimes damage the handled material. We present here a system of magnetic tweezers that overcomes those drawbacks while retaining most of the previous dynamometers properties. Electromagnets are coupled to a microscope-based particle tracking system through a digital feedback loop. Magnetic beads are first trapped in a potential well of stiffness approximately 10(-7) N/m. Thus, they can be manipulated in three dimensions at a speed of approximately 10 microm/s and rotated along the optical axis at a frequency of 10 Hz. In addition, our apparatus can work as a dynamometer relying on either usual calibration against the viscous drag or complete calibration using Brownian fluctuations. By stretching a DNA molecule between a magnetic particle and a glass surface, we applied and measured vertical forces ranging from 50 fN to 20 pN. Similarly, nearly horizontal forces up to 5 pN were obtained. From those experiments, we conclude that magnetic tweezers represent a low-cost and biocompatible setup that could become a suitable alternative to the other available micromanipulators. PMID:12023254

  9. Electromagnetic tweezers with independent force and torque control

    NASA Astrophysics Data System (ADS)

    Jiang, Chang; Lionberger, Troy A.; Wiener, Diane M.; Meyhofer, Edgar

    2016-08-01

    Magnetic tweezers are powerful tools to manipulate and study the mechanical properties of biological molecules and living cells. In this paper we present a novel, bona fide electromagnetic tweezer (EMT) setup that allows independent control of the force and torque applied via micrometer-sized magnetic beads to a molecule under study. We implemented this EMT by combining a single solenoid that generates force (f-EMT) with a set of four solenoids arranged into a symmetric quadrupole to generate torque (τ-EMT). To demonstrate the capability of the tweezers, we attached optically asymmetric Janus beads to single, tethered DNA molecules. We show that tension in the piconewton force range can be applied to single DNA molecules and the molecule can simultaneously be twisted with torques in the piconewton-nanometer range. Furthermore, the EMT allows the two components to be independently controlled. At various force levels applied to the Janus bead, the trap torsional stiffness can be continuously changed simply by varying the current magnitude applied to the τ-EMT. The flexible and independent control of force and torque by the EMT makes it an ideal tool for a range of measurements where tensional and torsional properties need to be studied simultaneously on a molecular or cellular level.

  10. Theory of optical-tweezers forces near a plane interface

    NASA Astrophysics Data System (ADS)

    Dutra, R. S.; Neto, P. A. Maia; Nussenzveig, H. M.; Flyvbjerg, H.

    2016-11-01

    Optical-tweezers experiments in molecular and cell biology often take place near the surface of the microscope slide that defines the bottom of the sample chamber. There, as elsewhere, force measurements require force-calibrated tweezers. In bulk, one can calculate the tweezers force from first principles, as recently demonstrated. Near the surface of the microscope slide, this absolute calibration method fails because it does not account for reverberations from the slide of the laser beam scattered by the trapped microsphere. Nor does it account for evanescent waves arising from total internal reflection of wide-angle components of the strongly focused beam. In the present work we account for both of these phenomena. We employ Weyl's angular spectrum representation of spherical waves in terms of real and complex rays and derive a fast-converging recursive series of multiple reflections that describes the reverberations, including also evanescent waves. Numerical simulations for typical setup parameters evaluate these effects on the optical force and trap stiffness, with emphasis on axial trapping. Results are in good agreement with available experimental data. Thus, absolute calibration now applies to all situations encountered in practice.

  11. Hooking-Up, Religiosity, and Sexting Among College Students.

    PubMed

    Hall, Michael; Williams, Ronald D; Ford, M Allison; Cromeans, Erin Murphy; Bergman, Randall J

    2016-07-28

    The purpose of this study was to evaluate the mediation effect of sexting, and taking sexually suggestive photos on religiosity and hooking-up with three separate sexual outcomes. A web-based survey examined the relationship between religiosity and the three hooking-up outcomes among students reporting sexting or taking a sexually suggestive photo in the last 30 days (n = 231). Sexting, as well as taking sexually suggestive photos mediated the relationship between religiosity and hooking-up among females. Sexting may be initiated by females as a way to engage in a nonphysical sexual interaction, which ultimately predisposes them to a physical sexual outcome.

  12. Fractures of the hook of hamate: radiographic signs

    SciTech Connect

    Norman, A.; Nelson, J.; Green, S.

    1985-01-01

    Isolated fractures of the hamulus, formerly considered rare, are being seen more frequently. Many of these injuries are sports related, particularly in golf, tennis, racquetball and baseball players. Failure to make an early diagnosis can result in severe pain and sometimes incapacitating disability. The authors studied the clinical and radiological findings in 12 patients who had fracture of the hook of the hamate. The proposed three radiographic signs of fracture that are readily seen on routine PA projections: absence of the hook of the hamate; sclerosis of the hook; and lack of cortical density, i.e., barely visible outline, of the hamulus.

  13. 4. VIEW FROM NORTH SIDE UP TO CRANE, SHOWING HOOK ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW FROM NORTH SIDE UP TO CRANE, SHOWING HOOK FOR LIFTING HEAD GATES AND OPERATOR DECK - Cabot Station Electric Generating Plant, Gantry Crane, Montague City Road, Turners Falls vicinity, Montague, Franklin County, MA

  14. Relationship between tornadoes and hook echoes on April 3, 1974

    NASA Technical Reports Server (NTRS)

    Forbes, G. S.

    1975-01-01

    Radar observations of tornado families occurring on April 3, 1974 are discussed. Of the 93 tornadoes included in the sample, 81% were associated with hook-like echoes with appendages at least 40 deg to the south of the echo movement. At least one tornado was associated with 62% of the hook-like echoes observed. All of the tornadoes with intensities of F 4 and F 5 were produced by hook-like echoes; the mean intensity of all tornadoes associated with this type of echo was F 3, while the mean intensity of the remaining tornadoes was F1. The tornadic hook-like echoes moved to the right of the non-tornadic echoes forming a tornado line in advance of the squall line. Some tornadoes were associated with 'spiral' echoes.

  15. Construction of supramolecular hyperbranched polymers via the "tweezering directed self-assembly" strategy.

    PubMed

    Tian, Yu-Kui; Yang, Zhi-Shuai; Lv, Xiao-Qin; Yao, Ri-Sheng; Wang, Feng

    2014-08-28

    A bis-alkynylplatinum(II) terpyridine tweezer-alkynylgold(III) diphenylpyridine guest is shown to maintain the specific complexation in the presence of a B21C7-secondary ammonium salt recognition motif, which facilitates the formation of supramolecular hyperbranched polymers via the "tweezering directed self-assembly" strategy.

  16. Linear microrheology with optical tweezers of living cells 'is not an option'!

    PubMed

    Tassieri, Manlio

    2015-08-07

    Optical tweezers have been successfully adopted as exceptionally sensitive transducers for microrheology studies of complex fluids. Despite the general trend, in this article I explain why a similar approach should not be adopted for microrheology studies of living cells. This conclusion is acheived on the basis of statistical mechanics principles that indicate the unsuitability of optical tweezers for such purpose.

  17. Performance of barbed and barbless hooks in a marine recreational fishery

    USGS Publications Warehouse

    Schaeffer, Jeffrey S.; Hoffman, Elizabeth M.

    2002-01-01

    We used an angling study to examine catch per unit effort (CPUE), bait loss, and total landings by anglers fishing with natural bait on barbed and barbless hooks in a nearshore marine sport fishery located in the Gulf of Mexico near St. Petersburg, Florida. Anglers fished half the day with a barbed hook and half the day with a barbless hook. We also recorded anatomical hook placement, severity of injury or bleeding, and hook extraction times for each landed fish. Bait loss, CPUE, and mean length of catch did not differ between gears, but anglers landed 22% more fish with barbed hooks. Loss of hooked fish was significantly higher with barbless hooks, and efficiency appeared to vary among species. Mean unhooking times were significantly shorter with barbless hooks. Anatomical hook placement did not differ between gears and most fish were hooked in the jaws. Bleeding did not differ between gears because bleeding was influenced strongly by hook placement, but barbless hooks reduced unhooking injuries. In this fishery, barbless hooks probably did not reduce hooking mortality and conferred only slight benefits at the expense of reduced catches.

  18. Properties of crimpable archwire hooks: a laboratory investigation.

    PubMed

    Johal, A; Harper, C R; Sherriff, M

    1999-12-01

    The aim of the present study was to utilize a strain gauge, which enabled the force applied to produce firmly attached crimpable hooks to rectangular stainless steel arch wires, to be measured. In vitro testing of two hooks, American Orthodontic (AO) and TP Orthodontic (TP), and two dimensions of stainless steel archwire, 0.019 x 0.025 and 0.018 x 0.025-inch, was carried out using an Instron Universal Testing machine. The results demonstrate that there was a significant difference in the behaviour of the two types of crimpable hooks, with almost twice the force needed to dislodge the TP hooks compared with the AO hooks (11.7 and 6.22 N, respectively). When using TP hooks attached to either 0.019 x 0.025 or 0.018 x 0.025-inch stainless steel wires, the archwire size makes little difference to the force required to produce movement. The clinical significance of these findings is discussed.

  19. Debakey forceps crushing technique for hepatic parenchymal transection in liver surgery: a review of 100 cases and ergonomic advantages.

    PubMed

    Jain, Sundeep; Sharma, Bharat; Kaushik, Mitesh; Jain, Lokendra

    2014-01-01

    Introduction and Objective. Bleeding is an important complication in liver transections. To determine the safety and efficacy of Debakey forceps for liver parenchymal transection and its ergonomic advantages over clamp crushing method we analysed our data. Methods. We used Debakey crushing technique in 100 liver resections and analysed data for transection time, transfusion rate, morbidity, mortality, hospital stay, influence of different types of liver conditions, and ergonomi features of Debakey forceps. Results. Mean age, transection time and hospital stay of 100 patients were 52.38 ± 17.44 years, 63.36 ± 33.4 minutes, and 10.27 ± 5.7 days. Transection time, and hospital stay in patients with cirrhotic liver (130.4 ± 44.4 mins, 14.6 ± 5.5 days) and cholestatic liver (75.8 ± 19.7 mins, 16.5 ± 5.1 days) were significantly greater than in patients with normal liver (48.1 ± 20.1 mins, 6.7 ± 1.8 days) (P < 0.01). Transection time improved significantly with experience (first fifty versus second fifty cases-70.2 ± 31.1 mins versus 56.5 ± 34.5 mins, P < 0.04). Qualitative evaluation revealed that Debakey forceps had ergonomic advantages over Kelly clamp. Conclusions. Debakey forceps crushing technique is safe and effective for liver parenchymal transection in all kinds of liver. Transection time improves with surgeon's experience. It has ergonomic advantages over Kelly clamp and is a better choice for liver transection.

  20. Debakey Forceps Crushing Technique for Hepatic Parenchymal Transection in Liver Surgery: A Review of 100 Cases and Ergonomic Advantages

    PubMed Central

    Jain, Sundeep; Sharma, Bharat; Kaushik, Mitesh; Jain, Lokendra

    2014-01-01

    Introduction and Objective. Bleeding is an important complication in liver transections. To determine the safety and efficacy of Debakey forceps for liver parenchymal transection and its ergonomic advantages over clamp crushing method we analysed our data. Methods. We used Debakey crushing technique in 100 liver resections and analysed data for transection time, transfusion rate, morbidity, mortality, hospital stay, influence of different types of liver conditions, and ergonomi features of Debakey forceps. Results. Mean age, transection time and hospital stay of 100 patients were 52.38 ± 17.44 years, 63.36 ± 33.4 minutes, and 10.27 ± 5.7 days. Transection time, and hospital stay in patients with cirrhotic liver (130.4 ± 44.4 mins, 14.6 ± 5.5 days) and cholestatic liver (75.8 ± 19.7 mins, 16.5 ± 5.1 days) were significantly greater than in patients with normal liver (48.1 ± 20.1 mins, 6.7 ± 1.8 days) (P < 0.01). Transection time improved significantly with experience (first fifty versus second fifty cases—70.2 ± 31.1 mins versus 56.5 ± 34.5 mins, P < 0.04). Qualitative evaluation revealed that Debakey forceps had ergonomic advantages over Kelly clamp. Conclusions. Debakey forceps crushing technique is safe and effective for liver parenchymal transection in all kinds of liver. Transection time improves with surgeon's experience. It has ergonomic advantages over Kelly clamp and is a better choice for liver transection. PMID:25009367

  1. pH-stimulated concurrent mechanical activation of two DNA "tweezers". A "SET-RESET" logic gate system.

    PubMed

    Elbaz, Johann; Wang, Zhen-Gang; Orbach, Ron; Willner, Itamar

    2009-12-01

    A DNA tweezer consisting of C-rich arms is kept in the "closed" form by hybridization of the arms with a nucleic acid cross-linker. At acidic pH (pH = 5.2), the arms are stabilized through the formation of the i-motif, C-quadruplex structures, releasing the cross-linking nucleic acid and transforming the tweezer to its "opened" state. At neutral pH (pH = 7.2), the C-quadruplex structures are dissociated, resulting in the capturing of the cross-linking nucleic acid and the closure of the tweezer. By the reversible treatment of the tweezer at pH = 5.2 and at pH = 7.2, the tweezer system is cycled between the open and closed states, respectively, followed by a FRET process between a fluorophore-quencher pair that labels the tweezer. Also the concurrent activation of two DNA tweezers by pH stimuli is described. The pH-induced opening of one tweezer (tweezer A) by the formation of C-quadruplex (pH = 5.2) and the release of the cross-linking nucleic acid result in the closure of a second tweezer (tweezer B) by the hybridization of the released strand with the arms of tweezer B. The dissociation of the C-quadruplex structures (pH = 7.2) results in the favored translocation of the cross-linking nucleic acid from tweezer B to A. By the cycling of the pH of the system between pH = 5.2 and pH = 7.2, the concurrent opening and closure of the two tweezers are accomplished. The two tweezers system performs a SET-RESET logic gate operation, where the pH stimuli act as inputs.

  2. Asymmetric forceps increase fighting success among males of similar size in the maritime earwig

    PubMed Central

    Munoz, Nicole E.; Zink, Andrew G.

    2012-01-01

    Extreme asymmetric morphologies are hypothesized to serve an adaptive function that counteracts sexual selection for symmetry. However direct tests of function for asymmetries are lacking, particularly in the context of animal weapons. The weapon of the maritime earwig, Anisolabis maritima, exhibits sizeable variation in the extent of directional asymmetry within and across body sizes, making it an ideal candidate for investigating the function of asymmetry. In this study, we characterized the extent of weapon asymmetry, characterized the manner in which asymmetric weapons are used in contests, staged dyadic contests between males of different size classes and analyzed the correlates of fighting success. In contests between large males, larger individuals won more fights and emerged as the dominant male. In contests between small males, however, weapon asymmetry was more influential in predicting overall fighting success than body size. This result reveals an advantage of asymmetric weaponry among males that are below the mean size in the population. A forceps manipulation experiment suggests that asymmetry may be an indirect, correlate of a morphologically independent factor that affects fighting ability. PMID:22984320

  3. Novel modular 2-DOF microsurgical forceps for transoral laser microsurgeries: Ergonomic design and preliminary evaluation.

    PubMed

    Chauhan, Manish; Barresi, Giacinto; Deshpande, Nikhil; Caldwell, Darwin G; Mattos, Leonardo S

    2016-08-01

    Transoral Laser Microsurgeries (TLM) demand a great level of control and precision in intraoperative tissue manipulation. The optimal eradication of the diseased tissue is possible only with coordinated control of the laser aiming for incision and the microsurgical tools for orienting and stretching the tissue. However, the traditional microsurgical tools are long, single purpose, one degree-of-freedom (DOF), rigid tools with small range of motion and a normal grasping handle inducing non-ergonomic usage. This paper presents a novel, modular microsurgical tool to overcome the challenges of the traditional tools and improve the surgeon-tool usage experience. The novel design adds a rotational DOF to expand the reach and functionality of the tool. The device is provided with an ergonomic grasping handle that avoids extreme wrist excursions and is capable of adapting to the variety of tools used in TLM within the same design. The performance of the new microsurgical tool was evaluated through a subjective assessment with both medical students and expert surgeons. The evaluation demonstrated a general acceptance of the new forceps tool, with the expert surgeons providing positive appraisals for the improved functionality and user experience with the tool, which indicates towards the potential suitability of the device for TLM. The parameters assessed in the preliminary evaluation not only provide a sense of the advantages of the novel design, but also guide future evolution of the tool design.

  4. Robot-assisted microsurgical forceps with haptic feedback for transoral laser microsurgery.

    PubMed

    Deshpande, Nikhil; Chauhan, Manish; Pacchierotti, Claudio; Prattichizzo, Domenico; Caldwell, Darwin G; Mattos, Leonardo S

    2016-08-01

    In this paper, a novel, motorized, multi-degrees-of-freedom (DoF), microsurgical forceps tool is presented, which is based on a master-slave teleoperation architecture. The slave device is a 7-DoF manipulator with: (i) 6-DoF positioning and orientation, (ii) 1 open/close gripper DoF; and (iii) an integrated force/torque sensor for tissue grip-force measurement. The master device is a 7-DoF haptic interface which teleoperates the slave device, and provides haptic feedback in its gripper interface. The combination of the device and the surgeon interface replaces the manual, hand-held device providing easy-to-use and ergonomic tissue control, simplifying the surgical tasks. This makes the system suitable to real surgical scenarios in the operating room (OR). The performance of the system was analysed through the evaluation of teleoperation control and characterization of gripping force. The new system offers an overall positioning error of less than 400 μm demonstrating its safety and accuracy. Improved system precision, usability, and ergonomics point to the potential suitability of the device for the OR and its ability to advance haptic-feedback-enhanced transoral laser microsurgeries.

  5. Clathrin-Mediated Auxin Efflux and Maxima Regulate Hypocotyl Hook Formation and Light-Stimulated Hook Opening in Arabidopsis.

    PubMed

    Yu, Qinqin; Zhang, Ying; Wang, Juan; Yan, Xu; Wang, Chao; Xu, Jian; Pan, Jianwei

    2016-01-04

    The establishment of auxin maxima by PIN-FORMED 3 (PIN3)- and AUXIN RESISTANT 1/LIKE AUX1 (LAX) 3 (AUX1/LAX3)-mediated auxin transport is essential for hook formation in Arabidopsis hypocotyls. Until now, however, the underlying regulatory mechanism has remained poorly understood. Here, we show that loss of function of clathrin light chain CLC2 and CLC3 genes enhanced auxin maxima and thereby hook curvature, alleviated the inhibitory effect of auxin overproduction on auxin maxima and hook curvature, and delayed blue light-stimulated auxin maxima reduction and hook opening. Moreover, pharmacological experiments revealed that auxin maxima formation and hook curvature in clc2 clc3 were sensitive to auxin efflux inhibitors 1-naphthylphthalamic acid and 2,3,5-triiodobenzoic acid but not to the auxin influx inhibitor 1-naphthoxyacetic acid. Live-cell imaging analysis further uncovered that loss of CLC2 and CLC3 function impaired PIN3 endocytosis and promoted its lateralization in the cortical cells but did not affect AUX1 localization. Taken together, these results suggest that clathrin regulates auxin maxima and thereby hook formation through modulating PIN3 localization and auxin efflux, providing a novel mechanism that integrates developmental signals and environmental cues to regulate plant skotomorphogenesis and photomorphogenesis.

  6. Interferometer-Controlled Optical Tweezers Constructed for Nanotechnology and Biotechnology

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2002-01-01

    A new method to control microparticles was developed in-house at the NASA Glenn Research Center in support of the nanotechnology project under NASA's Aerospace Propulsion and Power Base Research Program. A prototype interferometer-controlled optical tweezers was constructed to manipulate scanning probe microscope (SPM) tips. A laser beam passed through a Mach-Zehnder interferometer, and a microscope objective then produced an optical trap from the coaxial beams. The trap levitated and generated the coarse motion of a 10-mm polystyrene sphere used to simulate a SPM tip. The interference between the beams provided fine control of the forces and moments on the sphere. The interferometer included a piezoelectric-scanned mirror to modulate the interference pattern. The 10-mm sphere was observed to oscillate about 1 mm as the mirror and fringe pattern oscillated. The prototype tweezers proved the feasibility of constructing a more sophisticated interferometer tweezers to hold and manipulate SPM tips. The SPM tips are intended to interrogate and manipulate nanostructures. A more powerful laser will be used to generate multiple traps to hold nanostructures and SPM tips. The vibrating mirror in the interferometer will be replaced with a spatial light modulator. The modulator will allow the optical phase distribution in one leg of the interferometer to be programmed independently at 640 by 480 points for detailed control of the forces and moments. The interference patterns will be monitored to measure the motion of the SPM tips. Neuralnetwork technology will provide fast analysis of the interference patterns for diagnostic purposes and for local or remote feedback control of the tips. This effort also requires theoretical and modeling support in the form of scattering calculations for twin coherent beams from nonspherical particles.

  7. A simple optical tweezers for trapping polystyrene particles

    NASA Astrophysics Data System (ADS)

    Shiddiq, Minarni; Nasir, Zulfa; Yogasari, Dwiyana

    2013-09-01

    Optical tweezers is an optical trap. For decades, it has become an optical tool that can trap and manipulate any particle from the very small size like DNA to the big one like bacteria. The trapping force comes from the radiation pressure of laser light which is focused to a group of particles. Optical tweezers has been used in many research areas such as atomic physics, medical physics, biophysics, and chemistry. Here, a simple optical tweezers has been constructed using a modified Leybold laboratory optical microscope. The ocular lens of the microscope has been removed for laser light and digital camera accesses. A laser light from a Coherent diode laser with wavelength λ = 830 nm and power 50 mW is sent through an immersion oil objective lens with magnification 100 × and NA 1.25 to a cell made from microscope slides containing polystyrene particles. Polystyrene particles with size 3 μm and 10 μm are used. A CMOS Thorlabs camera type DCC1545M with USB Interface and Thorlabs camera lens 35 mm are connected to a desktop and used to monitor the trapping and measure the stiffness of the trap. The camera is accompanied by camera software which makes able for the user to capture and save images. The images are analyzed using ImageJ and Scion macro. The polystyrene particles have been trapped successfully. The stiffness of the trap depends on the size of the particles and the power of the laser. The stiffness increases linearly with power and decreases as the particle size larger.

  8. Analysis of micro-fluidic tweezers in the Stokes regime

    NASA Astrophysics Data System (ADS)

    Zhao, Longhua; Ding, Yang

    2016-11-01

    Nanowire fluidic tweezers have been developed to capture and manipulate micro objects. The fluidic trapping force and the fluid field are important to achieve accurate control, but have not been fully understood yet. Utilizing singularity method, we construct the exact velocity field to analyze flows induced by a spheroid nanowire tumbling in the Stokes regime. To further explore the trapping, we analyze the trajectories of rigid or deformable microspheres near the tumbling nanowire using regularized Stokeslet method. The fluid structure, the trapping phenomenon and mechanism, and precise relation about trapping with the geometry will be presented. YD is sponsored by the Recruitment Program of Global Young Experts (China).

  9. Optical Tweezers for Sample Fixing in Micro-Diffraction Experiments

    SciTech Connect

    Amenitsch, H.; Rappolt, M.; Sartori, B.; Laggner, P.; Cojoc, D.; Ferrari, E.; Garbin, V.; Di Fabrizio, E.; Burghammer, M.; Riekel, Ch.

    2007-01-19

    In order to manipulate, characterize and measure the micro-diffraction of individual structural elements down to single phospholipid liposomes we have been using optical tweezers (OT) combined with an imaging microscope. We were able to install the OT system at the microfocus beamline ID13 at the ESRF and trap clusters of about 50 multi-lamellar liposomes (< 10 {mu}m large cluster). Further we have performed a scanning diffraction experiment with a 1 micrometer beam to demonstrate the fixing capabilities and to confirm the size of the liposome cluster by X-ray diffraction.

  10. Advances in magnetic tweezers for single molecule and cell biophysics.

    PubMed

    Kilinc, Devrim; Lee, Gil U

    2014-01-01

    Magnetic tweezers (MTW) enable highly accurate forces to be transduced to molecules to study mechanotransduction at the molecular or cellular level. We review recent MTW studies in single molecule and cell biophysics that demonstrate the flexibility of this technique. We also discuss technical advances in the method on several fronts, i.e., from novel approaches for the measurement of torque to multiplexed biophysical assays. Finally, we describe multi-component nanorods with enhanced optical and magnetic properties and discuss their potential as future MTW probes.

  11. Single molecule studies of helicases with magnetic tweezers.

    PubMed

    Hodeib, Samar; Raj, Saurabh; Manosas, M; Zhang, Weiting; Bagchi, Debjani; Ducos, Bertrand; Allemand, Jean-François; Bensimon, David; Croquette, Vincent

    2016-08-01

    Helicases are a broad family of enzymes that perform crucial functions in DNA replication and in the maintenance of DNA and RNA integrity. A detailed mechanical study of helicases on DNA and RNA is possible using single molecule manipulation methods. Among those, magnetic tweezers (or traps) present a convenient, moderate throughput assay (tens of enzymes can be monitored simultaneously) that allow for high resolution (single base-pair) studies of these enzymes in various conditions and on various substrates (double and single stranded DNA and RNA). Here we discuss various implementation of the basic assay relevant for these studies.

  12. Optical tweezers studies of transcription by eukaryotic RNA polymerases.

    PubMed

    Lisica, Ana; Grill, Stephan W

    2017-02-21

    Transcription is the first step in the expression of genetic information and it is carried out by large macromolecular enzymes called RNA polymerases. Transcription has been studied for many years and with a myriad of experimental techniques, ranging from bulk studies to high-resolution transcript sequencing. In this review, we emphasise the advantages of using single-molecule techniques, particularly optical tweezers, to study transcription dynamics. We give an overview of the latest results in the single-molecule transcription field, focusing on transcription by eukaryotic RNA polymerases. Finally, we evaluate recent quantitative models that describe the biophysics of RNA polymerase translocation and backtracking dynamics.

  13. Engineering Evaluation of International Low Impact Docking System Latch Hooks

    NASA Technical Reports Server (NTRS)

    Martinez, J.; Patin, R.; Figert, J.

    2013-01-01

    The international Low Impact Docking System (iLIDS) provides a structural arrangement that allows for visiting vehicles to dock with the International Space Station (ISS) (Fig 1). The iLIDS docking units are mechanically joined together by a series of active and passive latch hooks. In order to preserve docking capability at the existing Russian docking interfaces, the iLIDS latch hooks are required to conform to the existing Russian design. The latch hooks are classified as being fail-safe. Since the latch hooks are fail-safe, the hooks are not fracture critical and a fatigue based service life assessment will satisfy the structural integrity requirements. Constant amplitude fatigue testing to failure on four sets of active/passive iLIDS latch hooks was performed at load magnitudes of 10, 11, and 12 kips. Failure analysis of the hook fatigue failures identified multi-site fatigue initiation that was effectively centered about the hook mid-plane (consistent with the 3D model results). The fatigue crack initiation distribution implies that the fatigue damage accumulation effectively results in a very low aspect ratio surface crack (which can be simulated as thru-thickness crack). Fatigue damage progression resulted in numerous close proximity fatigue crack initiation sites. It was not possible to determine if fatigue crack coalescence occurs during cyclic loading or as result of the fast fracture response. The presence of multiple fatigue crack initiation sites on different planes will result in the formation of ratchet marks as the cracks coalesce. Once the stable fatigue crack becomes unstable and the fast fracture advances across the remaining ligament and the plane stress condition at a free-surface will result in failure along a 45 deg. shear plane (slant fracture) and the resulting inclined edge is called a shear lip. The hook thickness on the plane of fatigue crack initiation is 0.787". The distance between the shear lips on this plane was on the order of 0

  14. Optical tweezers: Characterization and systems approach to high bandwidth force estimation

    NASA Astrophysics Data System (ADS)

    Sehgal, Hullas

    In recent times, the hard boundaries between classical fields of sciences have almost disappeared. There is a cross-pollination of ideas between sciences, engineering and mathematics. This work investigates a modern tool of micro-manipulation of microscopic particles that is used primarily by bio-physicists and bio-chemists for single cell, single molecule studies. This tool called the Optical Tweezers can trap microscopic dielectric particles using radiation pressure of light. Optical tweezers is increasingly being used in bio-assays as it provides a means to observe bio-molecules non invasively and offers a spatial resolution in nanometers and force resolution in femto-Newtons at millisecond timescales. In this work, physics governing the operating principle behind optical tweezers is presented, followed by a step by step procedure to build an optical tweezers system having measurement and actuation capability along with a controller logic for feedback implementation. The working of optical tweezers system is presented using a spring mass damper model and the traditional methods of optical tweezers characterization are discussed. A comprehensive view of Optical tweezers is then presented from a system theoretic perspective, underlying the limitations of traditional methods of tweezers characterization that are based on the first principle. The role of feedback in Optical tweezers is presented along with the fundamental limitations that the plant model imposes on optical tweezers performance to be used as a force sensor for fast dynamics input force. The purpose of optical tweezers as a pico-newton force probe is emphasized and a classical controls based method to improve the bandwidth of force estimation using an ad-hoc approach of system inversion is presented. The efficacy of system inversion based method in improving the force probe capability of feedback enhanced optical tweezers is validated by experimental results. It is shown experimentally that the system

  15. Invited article: a review of haptic optical tweezers for an interactive microworld exploration.

    PubMed

    Pacoret, Cécile; Régnier, Stéphane

    2013-08-01

    This paper is the first review of haptic optical tweezers, a new technique which associates force feedback teleoperation with optical tweezers. This technique allows users to explore the microworld by sensing and exerting picoNewton-scale forces with trapped microspheres. Haptic optical tweezers also allow improved dexterity of micromanipulation and micro-assembly. One of the challenges of this technique is to sense and magnify picoNewton-scale forces by a factor of 10(12) to enable human operators to perceive interactions that they have never experienced before, such as adhesion phenomena, extremely low inertia, and high frequency dynamics of extremely small objects. The design of optical tweezers for high quality haptic feedback is challenging, given the requirements for very high sensitivity and dynamic stability. The concept, design process, and specification of optical tweezers reviewed here are focused on those intended for haptic teleoperation. In this paper, two new specific designs as well as the current state-of-the-art are presented. Moreover, the remaining important issues are identified for further developments. The initial results obtained are promising and demonstrate that optical tweezers have a significant potential for haptic exploration of the microworld. Haptic optical tweezers will become an invaluable tool for force feedback micromanipulation of biological samples and nano- and micro-assembly parts.

  16. Round-tip dielectrophoresis-based tweezers for single micro-object manipulation.

    PubMed

    Kodama, Taiga; Osaki, Toshihisa; Kawano, Ryuji; Kamiya, Koki; Miki, Norihisa; Takeuchi, Shoji

    2013-09-15

    In this paper, we present an efficient methodology to manipulate a single micro-object using round-tip positive dielectrophoresis-based tweezers. The tweezers consist of a glass needle with a round-tip and a pair of thin gold-film electrodes. The round-tip, which has a radius of 3µm, is formed by melting a finely pulled glass needle and concentrates the electric field at the tip of the tweezers, which allows the individual manipulation of single micro-objects. The tweezers successfully captured, conveyed, and positioned single cell-sized liposomes with diameters of 5-23µm, which are difficult to manipulate with conventional manipulation methodologies, such as optical tweezers or glass micropipettes, due to the similarities between their optical properties and those of the media, as well as the ease with which they are deformed or broken. We used Stokes' drag theory to experimentally evaluate the positive dielectrophoresis (pDEP) force generated by the tweezers as a function of the liposome size, the content of the surrounding media, and the applied AC voltage and frequency. The results agreed with the theoretically deduced pDEP force. Finally, we demonstrated the separation of labeled single cells from non-labeled cells with the tweezers. This device can be used as an efficient tool for precisely and individually manipulating biological micro-objects that are typically transparent and flexible.

  17. Developments of pulse laser assist optical tweezers (PLAT) for in vivo manipulation

    NASA Astrophysics Data System (ADS)

    Maeda, Saki; Sugiura, Tadao; Minato, Kotaro

    2011-02-01

    Optical tweezers is a technique to trap and to manipulate micron sized objects under a microscope by radiation pressure force exerted by a laser beam. Optical tweezers has been utilized for single-molecular measurements of force exerted by molecular interactions and for cell palpation. To extend applications of optical tweezers we have developed a novel optical tweezers system combined with a pulse laser. We utilize a pulsed laser (Q-switched Nd: YAG laser, wavelength of 1064 nm) to assist manipulations by conventional optical tweezers achieved by a continuous wave (CW) laser. The pulsed laser beam is introduced into the same optics for conventional optical tweezers. In principle, instantaneous radiation force is proportional to instantaneous power of laser beam. As a result, pulsed laser beam generates strong instantaneous force on an object to be manipulated. If the radiation force becomes strong enough to get over an obstacle structure and/or to be released from adhesion, the object will be free from these difficulties. We have named this technique as Pulse Laser beam Assisted optical Tweezers (PLAT). We have successfully demonstrated to manipulate objects surface on a living cell for "in vivo manipulation."

  18. Use of optical tweezers to probe epithelial mechanosensation

    NASA Astrophysics Data System (ADS)

    Resnick, Andrew

    2010-01-01

    Cellular mechanosensation mechanisms have been implicated in a variety of disease states. Specifically in renal tubules, the primary cilium and associated mechanosensitive ion channels are hypothesized to play a role in water and salt homeostasis, with relevant disease states including polycystic kidney disease and hypertension. Previous experiments investigating ciliary-mediated cellular mechanosensation have used either fluid flow chambers or micropipetting to elicit a biological response. The interpretation of these experiments in terms of the ``ciliary hypothesis'' has been difficult due the spatially distributed nature of the mechanical disturbance-several competing hypotheses regarding possible roles of primary cilium, glycocalyx, microvilli, cell junctions, and actin cytoskeleton exist. I report initial data using optical tweezers to manipulate individual primary cilia in an attempt to elicit a mechanotransduction response-specifically, the release of intracellular calcium. The advantage of using laser tweezers over previous work is that the applied disturbance is highly localized. I find that stimulation of a primary cilium elicits a response, while stimulation of the apical surface membrane does not. These results lend support to the hypothesis that the primary cilium mediates transduction of mechanical strain into a biochemical response in renal epithelia.

  19. Multiplexed single-molecule force proteolysis measurements using magnetic tweezers.

    PubMed

    Adhikari, Arjun S; Chai, Jack; Dunn, Alexander R

    2012-07-25

    The generation and detection of mechanical forces is a ubiquitous aspect of cell physiology, with direct relevance to cancer metastasis(1), atherogenesis(2) and wound healing(3). In each of these examples, cells both exert force on their surroundings and simultaneously enzymatically remodel the extracellular matrix (ECM). The effect of forces on ECM has thus become an area of considerable interest due to its likely biological and medical importance(4-7). Single molecule techniques such as optical trapping(8), atomic force microscopy(9), and magnetic tweezers(10,11) allow researchers to probe the function of enzymes at a molecular level by exerting forces on individual proteins. Of these techniques, magnetic tweezers (MT) are notable for their low cost and high throughput. MT exert forces in the range of ~1-100 pN and can provide millisecond temporal resolution, qualities that are well matched to the study of enzyme mechanism at the single-molecule level(12). Here we report a highly parallelizable MT assay to study the effect of force on the proteolysis of single protein molecules. We present the specific example of the proteolysis of a trimeric collagen peptide by matrix metalloproteinase 1 (MMP-1); however, this assay can be easily adapted to study other substrates and proteases.

  20. Multiplying optical tweezers force using a micro-lever.

    PubMed

    Lin, Chih-Lang; Lee, Yi-Hsiung; Lin, Chin-Te; Liu, Yi-Jui; Hwang, Jiann-Lih; Chung, Tien-Tung; Baldeck, Patrice L

    2011-10-10

    This study presents a photo-driven micro-lever fabricated to multiply optical forces using the two-photon polymerization 3D-microfabrication technique. The micro-lever is a second class lever comprising an optical trapping sphere, a beam, and a pivot. A micro-spring is placed between the short and long arms to characterize the induced force. This design enables precise manipulation of the micro-lever by optical tweezers at the micron scale. Under optical dragging, the sphere placed on the lever beam moves, resulting in torque that induces related force on the spring. The optical force applied at the sphere is approximately 100 to 300 pN, with a laser power of 100 to 300 mW. In this study, the optical tweezers drives the micro-lever successfully. The relationship between the optical force and the spring constant can be determined by using the principle of leverage. The arm ratio design developed in this study multiplies the applied optical force by 9. The experimental results are in good agreement with the simulation of spring property.

  1. Precision Assembly of Complex Cellular Microenvironments using Holographic Optical Tweezers

    PubMed Central

    Kirkham, Glen R.; Britchford, Emily; Upton, Thomas; Ware, James; Gibson, Graham M.; Devaud, Yannick; Ehrbar, Martin; Padgett, Miles; Allen, Stephanie; Buttery, Lee D.; Shakesheff, Kevin

    2015-01-01

    The accurate study of cellular microenvironments is limited by the lack of technologies that can manipulate cells in 3D at a sufficiently small length scale. The ability to build and manipulate multicellular microscopic structures will facilitate a more detailed understanding of cellular function in fields such as developmental and stem cell biology. We present a holographic optical tweezers based technology to accurately generate bespoke cellular micro-architectures. Using embryonic stem cells, 3D structures of varying geometries were created and stabilized using hydrogels and cell-cell adhesion methods. Control of chemical microenvironments was achieved by the temporal release of specific factors from polymer microparticles positioned within these constructs. Complex co-culture micro-environmental analogues were also generated to reproduce structures found within adult stem cell niches. The application of holographic optical tweezers-based micromanipulation will enable novel insights into biological microenvironments by allowing researchers to form complex architectures with sub-micron precision of cells, matrices and molecules. PMID:25716032

  2. Use of optical tweezers to probe epithelial mechanosensation.

    PubMed

    Resnick, Andrew

    2010-01-01

    Cellular mechanosensation mechanisms have been implicated in a variety of disease states. Specifically in renal tubules, the primary cilium and associated mechanosensitive ion channels are hypothesized to play a role in water and salt homeostasis, with relevant disease states including polycystic kidney disease and hypertension. Previous experiments investigating ciliary-mediated cellular mechanosensation have used either fluid flow chambers or micropipetting to elicit a biological response. The interpretation of these experiments in terms of the "ciliary hypothesis" has been difficult due the spatially distributed nature of the mechanical disturbance-several competing hypotheses regarding possible roles of primary cilium, glycocalyx, microvilli, cell junctions, and actin cytoskeleton exist. I report initial data using optical tweezers to manipulate individual primary cilia in an attempt to elicit a mechanotransduction response-specifically, the release of intracellular calcium. The advantage of using laser tweezers over previous work is that the applied disturbance is highly localized. I find that stimulation of a primary cilium elicits a response, while stimulation of the apical surface membrane does not. These results lend support to the hypothesis that the primary cilium mediates transduction of mechanical strain into a biochemical response in renal epithelia.

  3. Eos Interviews Robert Van Hook, Former AGU Interim Executive Director

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2010-08-01

    Robert Van Hook, who served as AGU's interim executive director since January 2009, led the organization during a transition period that began with the retirement of long-serving executive director A. F. (“Fred”) Spilhaus Jr. Van Hook's tenure concluded on 30 August when Christine McEntee assumed her position as AGU's new executive director (see Eos, 91(17), 153, 156, 2010). During his tenure at AGU, which overlapped with a global economic recession, Van Hook helped to guide the organization through key structural governance changes, strategic planning, and upgrades in technology, human resources, and accounting. He also helped to revitalize public outreach and member services, among many other efforts. Van Hook, president of Transition Management Consulting, recently reflected upon his tenure, the transition period, and the future of AGU. Van Hook credits AGU's strong volunteer leadership—including past presidents Tim Killeen and Tim Grove, current president Mike McPhaden, and president-elect Carol Finn—for courage in moving the organization through a successful transition. “They were the ones who shoved the boat off from the shore. I was lucky enough to be invited into the boat,” he said. He also credits the staff for their resiliency and commitment to supporting AGU's science.

  4. Interdependence of the rad50 hook and globular domain functions.

    PubMed

    Hohl, Marcel; Kochańczyk, Tomasz; Tous, Cristina; Aguilera, Andrés; Krężel, Artur; Petrini, John H J

    2015-02-05

    Rad50 contains a conserved Zn(2+) coordination domain (the Rad50 hook) that functions as a homodimerization interface. Hook ablation phenocopies Rad50 deficiency in all respects. Here, we focused on rad50 mutations flanking the Zn(2+)-coordinating hook cysteines. These mutants impaired hook-mediated dimerization, but recombination between sister chromatids was largely unaffected. This may reflect that cohesin-mediated sister chromatid interactions are sufficient for double-strand break repair. However, Mre11 complex functions specified by the globular domain, including Tel1 (ATM) activation, nonhomologous end joining, and DNA double-strand break end resection were affected, suggesting that dimerization exerts a broad influence on Mre11 complex function. These phenotypes were suppressed by mutations within the coiled-coil and globular ATPase domains, suggesting a model in which conformational changes in the hook and globular domains are transmitted via the extended coils of Rad50. We propose that transmission of spatial information in this manner underlies the regulation of Mre11 complex functions.

  5. Interdependence of the Rad50 hook and globular domain functions

    PubMed Central

    Hohl, Marcel; Kochańczyk, Tomasz; Tous, Cristina; Aguilera, Andrés; Krężel, Artur; Petrini, John H J

    2015-01-01

    SUMMARY Rad50 contains a conserved Zn2+ coordination domain (the Rad50 hook) that functions as a homodimerization interface. Hook ablation phenocopies Rad50 deficiency in all respects. Here we focused on rad50 mutations flanking the Zn2+-coordinating hook cysteines. These mutants impaired hook-mediated dimerization, but recombination between sister chromatids was largely unaffected. This may reflect that cohesin-mediated sister chromatid interactions are sufficient for double strand break repair. However, Mre11 complex functions specified by the globular domain, including Tel1 (ATM) activation, nonhomologous end-joining, and DNA double strand break end resection were affected, suggesting that dimerization exerts a broad influence on Mre11 complex function. These phenotypes were suppressed by mutations within the coiled coil and globular ATPase domain, suggesting a model in which conformational changes in the hook and globular domains are transmitted via the extended coils of Rad50. We propose that transmission of spatial information in this manner underlies the regulation of Mre11 complex functions. PMID:25601756

  6. Multi-size, Multi-angle Microbipolar Forceps for Skull Base Surgery: Technical Note

    PubMed Central

    Borghei-Razavi, Hamid; Schick, Uta

    2015-01-01

    Objective Hemorrhage control in skull base surgery is critical but hindered by the lack of instruments suitable for coagulating structural curves and corners. The main impediment is that most of the instruments currently used are right-angled and unsuitable because anatomical and pathologic structures are three-dimensional objects having complex curves and corners. In this article, we present a solution: the use of angled bipolar microforceps having a range of small diameters and angles for dissection and coagulation. Methods Utilizing modern design software and up-to-date synthetic and metallic materials, a variety of nonstick bipolar microforceps with different angles and very fine tips (0.2–1.2 mm) were designed and constructed for use on different anatomical and pathologic curves. The tips of the forceps were made very fine to improve coagulation precision as well as to improve microdissection dexterity. The blades were made long and thin to improve visibility during coagulation and dissection procedures. As a result, these multi-size, multiangle micro instruments can be used not only for coagulation but also for microdissection or tumor removal in most anatomical areas accessed during the course of skull base surgery Results The research, design, and construction of a new bipolar microforceps with different angles and sizes represents a technical innovation that can lead to improved surgical outcomes. Conclusion The new micro-instruments enhance the quality and quantity of tumor and tissue resection and dissection in skull base surgery and open the possibility of new surgical approaches to microscopic tumor resection and hemorrhage coagulation in the anatomical areas of the skull base. PMID:26251793

  7. Inducing trauma into neuroblastoma cells and synthetic neural networks using optical tweezers

    NASA Astrophysics Data System (ADS)

    Schneider, Patrick William

    The laser tweezers have become a very useful tool in the fields of physics, chemistry, and biology. My intent is to use the laser tweezers to induce trauma into neuroblastoma cells, cells that resemble neural cells when treated with retinoic acid, to try to surmise what happens when neural cells and networks are disrupted or destroyed. The issues presented will deal with the obtaining, maintenance, and differentiation of the cells, as well as the inner operations of the laser tweezers themselves, and what kind of applications it has been applied to, as well as to my work in this project.

  8. Optical tweezers assisted quantitative phase imaging led to thickness mapping of red blood cells

    NASA Astrophysics Data System (ADS)

    Cardenas, Nelson; Mohanty, Samarendra K.

    2013-07-01

    Quantitative phase microscopy (QPM) allows dynamic mapping of optical path length of microscopic samples with high temporal and axial resolution. However, decoupling of the geometric thickness from the refractive index in phase measurements is challenging. Here, we report use of optical tweezers combined with QPM for decoupling geometric thickness from the refractive index. This is demonstrated by orienting the microscopic sample (red blood cell) by optical tweezers and imaging the phase at various orientations. Since optical tweezers can orient wide variety of micro and nanoscopic objects, this integrated method can be employed to accurately determine their physical properties.

  9. A simple method for evaluating the trapping performance of acoustic tweezers

    NASA Astrophysics Data System (ADS)

    Li, Ying; Lee, Changyang; Ho Lam, Kwok; Kirk Shung, K.

    2013-02-01

    The purpose of this paper is to present a rapid and simple method to evaluate the trapping performance of high frequency focused ultrasonic transducers for acoustic tweezer applications. The method takes into consideration the friction between the particle to be trapped and the surface that it resides on. As a result it should be more reliable and accurate than the methods proposed previously. The trapping force produced by a 70-MHz press-focused transducer was measured to evaluate the performance of this approach. This method demonstrates its potential in optimizing the excitation conditions for acoustic tweezer applications and the design of acoustic tweezers.

  10. A simple method for evaluating the trapping performance of acoustic tweezers.

    PubMed

    Li, Ying; Lee, Changyang; Ho Lam, Kwok; Kirk Shung, K

    2013-02-25

    The purpose of this paper is to present a rapid and simple method to evaluate the trapping performance of high frequency focused ultrasonic transducers for acoustic tweezer applications. The method takes into consideration the friction between the particle to be trapped and the surface that it resides on. As a result it should be more reliable and accurate than the methods proposed previously. The trapping force produced by a 70-MHz press-focused transducer was measured to evaluate the performance of this approach. This method demonstrates its potential in optimizing the excitation conditions for acoustic tweezer applications and the design of acoustic tweezers.

  11. Newton–Hooke-type symmetry of anisotropic oscillators

    SciTech Connect

    Zhang, P.M.; Horvathy, P.A.; Andrzejewski, K.; Gonera, J.; Kosiński, P.

    2013-06-15

    Rotation-less Newton–Hooke-type symmetry, found recently in the Hill problem, and instrumental for explaining the center-of-mass decomposition, is generalized to an arbitrary anisotropic oscillator in the plane. Conversely, the latter system is shown, by the orbit method, to be the most general one with such a symmetry. Full Newton–Hooke symmetry is recovered in the isotropic case. Star escape from a galaxy is studied as an application. -- Highlights: ► Rotation-less Newton–Hooke (NH) symmetry is generalized to an arbitrary anisotropic oscillator. ► The orbit method is used to find the most general case for rotation-less NH symmetry. ► The NH symmetry is decomposed into Heisenberg algebras based on chiral decomposition.

  12. EAARL Coastal Topography - Sandy Hook 2007

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Stevens, Sara; Yates, Xan; Bonisteel, Jamie M.

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Northeast Coastal and Barrier Network, Kingston, RI; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of Gateway National Recreation Area's Sandy Hook Unit in New Jersey, acquired on May 16, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL) was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then

  13. BOOK REVIEW: Robert Hooke and the Royal Society

    NASA Astrophysics Data System (ADS)

    Brown, Neil

    2000-01-01

    Many physics students only come across Hooke when they learn his law of stretching springs, which is a pity because it is just one of his contributions to progress in science, and a minor one at that. His, Micrographia, the first great book of microscopical observations, arouses admiration to this day. He was also active in horology, astronomy, geology and surveying, and he took part in biological experiments, transfusing blood between animals. Much of his work was done while he was curator of experiments for the Royal Society, in which he was involved almost from its foundation. This was by no means a full-time occupation, however. After the Great Fire of London, Hooke was appointed one of the three surveyors for the rebuilding of the city. One of the others was Christopher Wren, a lifelong friend. In this role Hooke was responsible for the design of several buildings, including the Monument. Nichols writes about all these activities, as well as Hooke's childhood, his education at Westminster School, the University of Oxford when Hooke was an undergraduate, and the founding of the Royal Society. The book draws on research for a master's degree. Turning a dissertation into a popular book is risky. The author has avoided the pitfall of making it too academic, but the result is not satisfying. Nichols seems overawed by Hooke and his work, frequently seeming to credit Hooke with a far-reaching influence that he did not necessarily have. There may be a case for lauding Hooke as the father of English microscopy, the father of English meteorology, and the founder of English geology and earth sciences, but it needs to be made much more critically, even in a popular work. Hooke was full of good ideas, but he rarely continued long enough to put them into practice. There is no doubt that Hooke proposed using a balance wheel and spring to improve the timekeeping of a watch, for example, but he did not have a watch made to his design until after Christiaan Huygens had

  14. The Clavicular Hook Plate: Consequences in Three Cases.

    PubMed

    Chandrasenan, Jeevan; Badhe, Sachin; Cresswell, Timothy; De Beer, Joe

    2007-10-01

    The small fragment AO clavicular hook plate is indicated for certain fractures of the lateral end of clavicle and for symptomatic acromio-clavicular joint dislocations where there is rupture of the stabilizing ligaments. The complex anatomy and biomechanics of the acromio-clavicular joint can lead to complications that result in damage to the joint itself or acromial erosion. In addition, the rotator cuff complex is at risk of injury when inserting the plate. We report three cases where patients who underwent hook plate fixation subsequently required removal of the implant due to complications previously unreported in current literature.

  15. TweezPal - Optical tweezers analysis and calibration software

    NASA Astrophysics Data System (ADS)

    Osterman, Natan

    2010-11-01

    Optical tweezers, a powerful tool for optical trapping, micromanipulation and force transduction, have in recent years become a standard technique commonly used in many research laboratories and university courses. Knowledge about the optical force acting on a trapped object can be gained only after a calibration procedure which has to be performed (by an expert) for each type of trapped objects. In this paper we present TweezPal, a user-friendly, standalone Windows software tool for optical tweezers analysis and calibration. Using TweezPal, the procedure can be performed in a matter of minutes even by non-expert users. The calibration is based on the Brownian motion of a particle trapped in a stationary optical trap, which is being monitored using video or photodiode detection. The particle trajectory is imported into the software which instantly calculates position histogram, trapping potential, stiffness and anisotropy. Program summaryProgram title: TweezPal Catalogue identifier: AEGR_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGR_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 44 891 No. of bytes in distributed program, including test data, etc.: 792 653 Distribution format: tar.gz Programming language: Borland Delphi Computer: Any PC running Microsoft Windows Operating system: Windows 95, 98, 2000, XP, Vista, 7 RAM: 12 Mbytes Classification: 3, 4.14, 18, 23 Nature of problem: Quick, robust and user-friendly calibration and analysis of optical tweezers. The optical trap is calibrated from the trajectory of a trapped particle undergoing Brownian motion in a stationary optical trap (input data) using two methods. Solution method: Elimination of the experimental drift in position data. Direct calculation of the trap stiffness from the positional

  16. Automated transportation of single cells using robot-tweezer manipulation system.

    PubMed

    Hu, Songyu; Sun, Dong

    2011-08-01

    Manipulation of biological cells becomes increasingly important in biomedical engineering to address challenge issues in cell-cell interaction, drug discovery, and tissue engineering. Significant demand for both accuracy and productivity in cell manipulation highlights the need for automated cell transportation with integrated robotics and micro/nano manipulation technologies. Optical tweezers, which use highly focused low-power laser beams to trap and manipulate particles at micro/nanoscale, have emerged as an essential tool for manipulating single cells. In this article, we propose to use a robot-tweezer manipulation system to solve the problem of automatic transportation of biological cells, where optical tweezers function as special robot end effectors. Dynamics equation of the cell in optical tweezers is analyzed. A closed-loop controller is designed for transporting and positioning cells. Experiments are performed on live cells to demonstrate the effectiveness of the proposed approach in effective cell positioning.

  17. Problem in Two Unknowns: Robert Hooke and a Worm in Newton's Apple.

    ERIC Educational Resources Information Center

    Weinstock, Robert

    1992-01-01

    Discusses the place that Robert Hooke has in science history versus the scientific contributions he made. Examines the relationship between Hooke and his contemporary, Isaac Newton, and Hooke's claims that Newton built on his ideas without receiving Newton's recognition. (26 references) (MDH)

  18. Manipulation and spectroscopy of a single particle by use of white-light optical tweezers

    NASA Astrophysics Data System (ADS)

    Li, Peng; Shi, Kebin; Liu, Zhiwen

    2005-01-01

    We demonstrate, for the first time to our knowledge, three-dimensional (3D) trapping and manipulation of microscopic objects by use of supercontinuum white light generated from photonic crystal fibers. Furthermore, we show that the supercontinuum white-light optical tweezers used have the unique capability to perform optical scattering spectroscopy of a single 3D trapped object over a broad wavelength range. These novel tweezers can potentially open a promising avenue toward simultaneous manipulation and characterization of microscopic objects.

  19. Chromosomal analysis and identification based on optical tweezers and Raman spectroscopy: comment

    NASA Astrophysics Data System (ADS)

    Bak, Jimmy; Jørgensen, Thomas M.

    2007-05-01

    The authors of the work: ‘Chromosomal analysis and identification based on optical tweezers and raman spectroscopy’ [Opt. Express 14, 5385 (2006], claim that they have been able to identify and differentiate between three human chromosomes with an optical-tweezer Raman Spectroscopic experimental (LTRS) set-up. The results and conclusions as they are presented in the paper are questionable, however, when the spectral data and data analysis are studied in greater detail.

  20. Measurement of interaction forces between red blood cells in aggregates by optical tweezers

    SciTech Connect

    Maklygin, A Yu; Priezzhev, A V; Karmenian, A; Nikitin, Sergei Yu; Obolenskii, I S; Lugovtsov, Andrei E; Kisun Li

    2012-06-30

    We have fabricated double-beam optical tweezers and demonstrated the possibility of their use for measuring the interaction forces between red blood cells (erythrocytes). It has been established experimentally that prolonged trapping of red blood cells in a tightly focused laser beam does not cause any visible changes in their shape or size. We have measured the interaction between red blood cells in the aggregate, deformed by optical tweezers.

  1. Peculiarities of RBC aggregation studied by double trap optical tweezers

    NASA Astrophysics Data System (ADS)

    Khokhlova, Maria D.; Lyubin, Evgeny V.; Zhdanov, Alexander G.; Rykova, Sofia Yu.; Krasnova, Tatyana N.; Sokolova, Irina A.; Fedyanin, Andrey A.

    2010-04-01

    Aggregation peculiarities of red blood cells (RBCs) in autologous plasma are studied using double trap optical tweezers technique. The positions of RBCs are controlled with submicrometer accuracy by two optical traps formed by strongly focused laser beams (λ=1064 nm). Quantitative measurements of interaction forces between RBCs in pair aggregates are performed. Depending on the RBCs aggregation force, four different end-points of disaggregation induced by optical trap movement are revealed. Analysis of experimental force dependence on the distance between two RBCs during disaggregation is in a good agreement with the model of ring-shaped interaction surfaces of RBCs in pair aggregate. Aggregation velocities measured are shown to be strongly different for healthy and pathologic (System Lupus Erythematosis - SLE) blood samples.

  2. Probing multiscale mechanics of collagen with optical tweezers

    NASA Astrophysics Data System (ADS)

    Shayegan, Marjan; Rezaei, Naghmeh; Lam, Norman H.; Altindal, Tuba; Wieczorek, Andrew; Forde, Nancy R.

    2013-09-01

    How the molecular structure of the structural, extracellular matrix protein collagen correlates with its mechanical properties at different hierarchical structural levels is not known. We demonstrate the utility of optical tweezers to probe collagen's mechanical response throughout its assembly hierarchy, from single molecule force-extension measurements through microrheology measurements on solutions of collagen molecules, collagen fibrillar gels and gelatin. These experiments enable the determination of collagen's flexibility, mechanics, and timescales and strengths of interaction at different levels of hierarchy, information critical to developing models of how collagen's physiological function and stability are influenced by its chemical composition. By investigating how the viscoelastic properties of collagen are affected by the presence of telopeptides, protein domains that strongly influence fibril formation, we demonstrate that these play a role in conferring transient elasticity to collagen solutions.

  3. Automated analysis of single cells using Laser Tweezers Raman Spectroscopy.

    PubMed

    Casabella, S; Scully, P; Goddard, N; Gardner, P

    2016-01-21

    In recent years, significant progress has been made into the label-free detection and discrimination of individual cancer cells using Laser Tweezers Raman Spectroscopy (LTRS). However, the majority of examples reported have involved manual trapping of cells, which is time consuming and may lead to different cell lines being analysed in discrete batches. A simple, low-cost microfluidic flow chamber is introduced which allows single cells to be optically trapped and analysed in an automated fashion, greatly reducing the level of operator input required. Two implementations of the flow chamber are discussed here; a basic single-channel device in which the fluid velocity is controlled manually, and a dual-channel device which permits the automated capture and analysis of multiple cell lines with no operator input. Results are presented for the discrimination of live epithelial prostate cells and lymphocytes, together with a consideration of the consequences of traditional 'batch analysis' typically used for LTRS of live cells.

  4. Kinect the dots: 3D control of optical tweezers

    NASA Astrophysics Data System (ADS)

    Shaw, Lucy; Preece, Daryl; Rubinsztein-Dunlop, Halina

    2013-07-01

    Holographically generated optical traps confine micron- and sub-micron sized particles close to the center of focused light beams. They also provide a way of trapping multiple particles and moving them in three dimensions. However, in many systems the user interface is not always advantageous or intuitive especially for collaborative work and when depth information is required. We discuss and evaluate a set of multi-beam optical tweezers that utilize off the shelf gaming technology to facilitate user interaction. We use the Microsoft Kinect sensor bar as a way of getting the user input required to generate arbitrary optical force fields and control optically trapped particles. We demonstrate that the system can also be used for dynamic light control.

  5. Combined holographic-mechanical optical tweezers: Construction, optimization, and calibration

    SciTech Connect

    Hanes, Richard D. L.; Jenkins, Matthew C.; Egelhaaf, Stefan U.

    2009-08-15

    A spatial light modulator (SLM) and a pair of galvanometer-mounted mirrors (GMM) were combined into an optical tweezers setup. This provides great flexibility as the SLM creates an array of traps, which can be moved smoothly and quickly with the GMM. To optimize performance, the effect of the incidence angle on the SLM with respect to phase and intensity response was investigated. Although it is common to use the SLM at an incidence angle of 45 deg., smaller angles give a full 2{pi} phase shift and an output intensity which is less dependent on the magnitude of the phase shift. The traps were calibrated using an active oscillatory technique and a passive probability distribution method.

  6. Dynamic excitations in membranes induced by optical tweezers.

    PubMed Central

    Bar-Ziv, R; Moses, E; Nelson, P

    1998-01-01

    We present the phenomenology of transformations in lipid bilayers that are excited by laser tweezers. A variety of dynamic instabilities and shape transformations are observed, including the pearling instability, expulsion of vesicles, and more exotic ones, such as the formation of passages. Our physical picture of the laser-membrane interaction is based on the generation of tension in the bilayer and loss of surface area. Although tension is the origin of the pearling instability, it does not suffice to explain expulsion of vesicles, where we observe opening of giant pores and creeping motion of bilayers. We present a quantitative theoretical framework to understand most of the observed phenomenology. The main hypothesis is that lipid is pulled into the optical trap by the familiar dielectric effect, is disrupted, and finally is repackaged into an optically unresolvable suspension of colloidal particles. This suspension, in turn, can produce osmotic pressure and depletion forces, driving the observed transformations. PMID:9649388

  7. Using Optical Tweezers to Study Cell Mechanics during Airway Reopening

    NASA Astrophysics Data System (ADS)

    Yalcin, Huseyin; Wang, Jing; Ghadiali, Samir; Ou-Yang, H. Daniel

    2006-03-01

    Patients suffering from the acute respiratory distress syndrome (ARDS) must be mechanically ventilated in order to survive. However, these ventilation protocols may generate injurious hydrodynamic stresses especially during low tidal volume (VT) ventilation when the flow of micron-sized air bubbles displace the surrounding liquid. In-vitro studies in our lab revealed that microbubble flows can severally damage lung epithelial cells (EC). The degree of injury was elevated for sub-confluent monolayers in small channel heights. Under these conditions, the micromechanics of individual EC may influence the degree of cellular injury. To investigate the role of cell mechanics, we used an oscillating Optical Tweezers (OT) technique to measure the intrinsic mechanical properties of EC before and after the flow of microbubbles. Knowledge of how the EC's micromechanical properties influence cell viability may lead to the development of novel treatment therapies that enhance the EC's ability to withstand injurious hydrodynamic stresses during ventilation treatment.

  8. The effect of immersion oil in optical tweezers.

    PubMed

    Mahmoudi, Ali; Reihani, S Nader S

    2011-08-01

    Optimized optical tweezers are of great importance for biological micromanipulation. In this paper, we present a detailed electromagnetic-based calculation of the spatial intensity distribution for a laser beam focused through a high numerical aperture objective when there are several discontinuities in the optical pathway of the system. For a common case of 3 interfaces we have shown that 0.01 increase in the refractive index of the immersion medium would shift the optimal trapping depth by 3-4 μm (0.2-0.6 μm) for aqueous (air) medium. For the first time, We have shown that the alteration of the refractive index of the immersion medium can be also used in aerosol trapping provided that larger increase in the refractive index is considered.

  9. Investigating collagen self-assembly with optical tweezers microrheology

    NASA Astrophysics Data System (ADS)

    Forde, Nancy; Shayegan, Marjan; Altindal, Tuba

    Collagen is the fundamental structural protein in vertebrates. Assembled from individual triple-helical proteins to make strong fibres, collagen is a beautiful example of a hierarchical self-assembling system. Using optical tweezers to perform microrheology measurements, we explore the dynamics of interactions between collagens responsible for their self-assembly and examine the development of heterogeneous mechanics during assembly into fibrillar gels. Telopeptides, short non-helical regions that flank the triple helix, have long been known to facilitate fibril self-assembly. We find that their removal not only slows down fibril nucleation but also results in a significant frequency-dependent reduction in the elastic modulus of collagens in solution. We interpret these results in terms of a model in which telopeptides facilitate transient intermolecular interactions, which enhance network connectivity in solution and lead to more rapid assembly in fibril-forming conditions. Current address: Department of Physics, McGill University.

  10. Extending the Range for Force Calibration in Magnetic Tweezers

    PubMed Central

    Daldrop, Peter; Brutzer, Hergen; Huhle, Alexander; Kauert, Dominik J.; Seidel, Ralf

    2015-01-01

    Magnetic tweezers are a wide-spread tool used to study the mechanics and the function of a large variety of biomolecules and biomolecular machines. This tool uses a magnetic particle and a strong magnetic field gradient to apply defined forces to the molecule of interest. Forces are typically quantified by analyzing the lateral fluctuations of the biomolecule-tethered particle in the direction perpendicular to the applied force. Since the magnetic field pins the anisotropy axis of the particle, the lateral fluctuations follow the geometry of a pendulum with a short pendulum length along and a long pendulum length perpendicular to the field lines. Typically, the short pendulum geometry is used for force calibration by power-spectral-density (PSD) analysis, because the movement of the bead in this direction can be approximated by a simple translational motion. Here, we provide a detailed analysis of the fluctuations according to the long pendulum geometry and show that for this direction, both the translational and the rotational motions of the particle have to be considered. We provide analytical formulas for the PSD of this coupled system that agree well with PSDs obtained in experiments and simulations and that finally allow a faithful quantification of the magnetic force for the long pendulum geometry. We furthermore demonstrate that this methodology allows the calibration of much larger forces than the short pendulum geometry in a tether-length-dependent manner. In addition, the accuracy of determination of the absolute force is improved. Our force calibration based on the long pendulum geometry will facilitate high-resolution magnetic-tweezers experiments that rely on short molecules and large forces, as well as highly parallelized measurements that use low frame rates. PMID:25992733

  11. Extending the range for force calibration in magnetic tweezers.

    PubMed

    Daldrop, Peter; Brutzer, Hergen; Huhle, Alexander; Kauert, Dominik J; Seidel, Ralf

    2015-05-19

    Magnetic tweezers are a wide-spread tool used to study the mechanics and the function of a large variety of biomolecules and biomolecular machines. This tool uses a magnetic particle and a strong magnetic field gradient to apply defined forces to the molecule of interest. Forces are typically quantified by analyzing the lateral fluctuations of the biomolecule-tethered particle in the direction perpendicular to the applied force. Since the magnetic field pins the anisotropy axis of the particle, the lateral fluctuations follow the geometry of a pendulum with a short pendulum length along and a long pendulum length perpendicular to the field lines. Typically, the short pendulum geometry is used for force calibration by power-spectral-density (PSD) analysis, because the movement of the bead in this direction can be approximated by a simple translational motion. Here, we provide a detailed analysis of the fluctuations according to the long pendulum geometry and show that for this direction, both the translational and the rotational motions of the particle have to be considered. We provide analytical formulas for the PSD of this coupled system that agree well with PSDs obtained in experiments and simulations and that finally allow a faithful quantification of the magnetic force for the long pendulum geometry. We furthermore demonstrate that this methodology allows the calibration of much larger forces than the short pendulum geometry in a tether-length-dependent manner. In addition, the accuracy of determination of the absolute force is improved. Our force calibration based on the long pendulum geometry will facilitate high-resolution magnetic-tweezers experiments that rely on short molecules and large forces, as well as highly parallelized measurements that use low frame rates.

  12. Investigation of inclined dual-fiber optical tweezers for 3D manipulation and force sensing.

    PubMed

    Liu, Yuxiang; Yu, Miao

    2009-08-03

    Optical tweezers provide a versatile tool in biological and physical researches. Optical tweezers based on optical fibers are more flexible and ready to be integrated when compared with those based on microscope objectives. In this paper, the three-dimensional (3D) trapping ability of an inclined dual-fiber optical tweezers is demonstrated. The trapping efficiency with respect to displacement is experimentally calibrated along two dimensions. The system is studied numerically using a modified ray-optics model. The spring constants obtained in the experiment are predicted by simulations. It is found both experimentally and numerically that there is a critical value for the fiber inclination angle to retain the 3D trapping ability. The inclined dual-fiber optical tweezers are demonstrated to be more robust to z-axis misalignment than the counter-propagating fiber optical tweezers, which is a special case of th former when the fiber inclination angle is 90 masculine. This inclined dual-fiber optical tweezers can serve as both a manipulator and a force sensor in integrated systems, such as microfluidic systems and lab-on-a-chip systems.

  13. Antimicrobial properties of star anise (Illicium verum Hook f).

    PubMed

    De, Minakshi; De, Amit Krishna; Sen, Parimal; Banerjee, Arun Baran

    2002-02-01

    Star anise (Illicium verum Hook f) has been shown to possess potent antimicrobial properties. Chemical studies indicate that a major portion of this antimicrobial property is due to anethole present in the dried fruit. Studies with isolated anethole (compared with standard anethole) indicated that it is effective against bacteria, yeast and fungal strains.

  14. 3. This machine in building #7 plated the hooks used ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. This machine in building #7 plated the hooks used on the cross chains in tire chains, by the 'pean' or mechanical process. This process was replaced when coated wire was introduced. - American Chain & Cable Company, East Princess Street (400 Block), York, York County, PA

  15. The Sandy Hook Elementary School shooting as tipping point

    PubMed Central

    Shultz, James M; Muschert, Glenn W; Dingwall, Alison; Cohen, Alyssa M

    2013-01-01

    Among rampage shooting massacres, the Sandy Hook Elementary School shooting on December 14, 2012 galvanized public attention. In this Commentary we examine the features of this episode of gun violence that has sparked strong reactions and energized discourse that may ultimately lead toward constructive solutions to diminish high rates of firearm deaths and injuries in the United States. PMID:28228989

  16. CAMERA IS ON CATWALK ABOVE MTR. CRANE HOOK LOWERS TOP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CAMERA IS ON CATWALK ABOVE MTR. CRANE HOOK LOWERS TOP PLUG ONTO REACTOR. NOTE PLANK-LIKE BRIDGE (WALKWAY) TO BALCONY AT UPPER RIGHT. INL NEGATIVE NO. 4502. Unknown Photographer, probable date 3/31/1952 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  17. School Safety in a Post-Sandy Hook World

    ERIC Educational Resources Information Center

    Trump, Kenneth S.

    2014-01-01

    In this report the author, who is a school safety expert, provides information about school safety in a post-Sandy Hook world. He presents the following: (1) Continuum of Threats and Responses; (2) The role social media plays; (3) Reliable Best Practices; (4) Policy and Funding--Climate and Context; (5) Policy and Funding--Things to Avoid; and (6)…

  18. Development of an externally powered prosthetic hook for amputees

    NASA Technical Reports Server (NTRS)

    Karchak, A., Jr.; Allen, J. R.; Bontrager, E. L.

    1973-01-01

    The powered hook with trigger finger appears to be a useful adaptation of a terminal device for an amputee when performing vocational activities involving the use of a powered tool requiring a trigger control. The proportional control system includes transducers and amplifiers and appears to have widespread application for control of any external power, whether it be in the orthotic or prosthetic field.

  19. Anharmonic Vibrations of an "Ideal" Hooke's Law Oscillator

    ERIC Educational Resources Information Center

    Thomchick, John; McKelvey, J. P.

    1978-01-01

    Presents a model describing the vibrations of a mass connected to fixed supports by "ideal" Hooke's law springs which may serve as a starting point in the study of the properties of irons in a crystal undergoing soft mode activated transition. (SL)

  20. Automated multi-parametric sorting of micron-sized particles via multi-trap laser tweezers

    NASA Astrophysics Data System (ADS)

    Kaputa, Daniel S.

    The capabilities of laser tweezers have rapidly expanded since the first demonstration by Ashkin and co-workers in 1970 of the ability to trap particles using optical energy. Laser tweezers have been used to measure piconewton forces in many biological and material science application, sort bacteria, measure DNA bond strength, and even perform microsurgery. The laser tweezers system developed for this dissertation foreshadows the next generation of laser tweezer systems that provide automated particle sorted based upon multiple criteria. Many laser tweezer sorting applications today entail the operator sorting cells from a bulk sample, one by one. This dissertation demonstrates the technologies of pattern recognition and image processing that allow for an entire microscope slide to be sorted without any operator intervention. We already live in an automated world where the cars we drive are built by machines instead of humans. The technology is there, and the only factors limiting the advancements of fully automated biological instrumentation is the lack of developers with the appropriate knowledge sets. This dissertation introduces the concept of sorting particles via a multi-parametric approach where several parameters such as size, fluorescence, and Raman spectra are used as sorting criteria. Since the advent of laser tweezers, several groups have demonstrated the ability to sort cells and other particle by size, or by fluorescence, or by any other parameter, but to our knowledge there does not exist a laser tweezer sorting system that can sort particles based upon multiple parameters. Sorting via a single parameter can be a severe limitation as the method lacks the robustness and class specificity that exists when sorting based upon multiple parameters. Simply put, it makes more sense to determine the worth of a baseball card by considering it's condition as well as it's age, rather then solely upon its condition. By adding another parameter such as the name of

  1. The value of forceps biopsy and core needle biopsy in prediction of pathologic complete remission in locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy.

    PubMed

    Tang, Jing-Hua; An, Xin; Lin, Xi; Gao, Yuan-Hong; Liu, Guo-Chen; Kong, Ling-Heng; Pan, Zhi-Zhong; Ding, Pei-Rong

    2015-10-20

    Patients with pathological complete remission (pCR) after treated with neoadjuvant chemoradiotherapy (nCRT) have better long-term outcome and may receive conservative treatments in locally advanced rectal cancer (LARC). The study aimed to evaluate the value of forceps biopsy and core needle biopsy in prediction of pCR in LARC treated with nCRT. In total, 120 patients entered this study. Sixty-one consecutive patients received preoperative forceps biopsy during endoscopic examination. Ex vivo core needle biopsy was performed in resected specimens of another 43 consecutive patients. The accuracy for ex vivo core needle biopsy was significantly higher than forceps biopsy (76.7% vs. 36.1%; p < 0.001). The sensitivity for ex vivo core needle biopsy was significantly lower in good responder (TRG 3) than poor responder (TRG ≤ 2) (52.9% vs. 94.1%; p = 0.017). In vivo core needle biopsy was further performed in 16 patients with good response. Eleven patients had residual cancer cells in final resected specimens, among whom 4 (36.4%) patients were biopsy positive. In conclusion, routine forceps biopsy was of limited value in identifying pCR after nCRT. Although core needle biopsy might further identify a subset of patients with residual cancer cells, the accuracy was not substantially increased in good responders.

  2. Fiber optical tweezers for microscale and nanoscale particle manipulation and force sensing

    NASA Astrophysics Data System (ADS)

    Liu, Yuxiang

    2011-12-01

    Optical tweezers have been an important tool in biology and physics for studying single molecules and colloidal systems. Most of current optical tweezers are built with microscope objectives, which are: i) expensive, ii) bulky and hard to integrate, iii) sensitive to environmental fluctuations, iv) limited in terms of working distances from the substrate, and v) rigid with the requirements on the substrate (transparent substrate made with glass and with a fixed thickness). These limitations of objective-based optical tweezers prevent them from being miniaturized. Fiber optical tweezers can provide a solution for cost reduction and miniaturization, and these optical tweezers can be potentially used in microfluidic systems. However, the existing fiber optical tweezers have the following limitations: i) low trapping efficiency due to weakly focused beams, ii) lack of the ability to control the positions of multiple particles simultaneously, and iii) limited functionalities. The overall objective of this dissertation work is to further the fundamental understanding of fiber optical tweezers through experimental study and modeling, and to develop novel fiber optical tweezers systems to enhance the capability and functionalities of fiber optical tweezers as microscale and nanoscale manipulators/sensors. The contributions of this dissertation work are summarized as follows. i) An enhanced understanding of the inclined dual-fiber optical tweezers (DFOTs) system has been achieved. Stable three dimensional (3D) optical trapping of a single micron-sized particle has been experimentally demonstrated. This is the first time that the trapping efficiency has been calibrated and the stiffness of the trap has been obtained in the experiments, which has been carried out by using two methods: the drag force method and power spectrum analysis. Such calibration enables the system to be used as a picoNewton-level force sensor in addition to a particle manipulator. The influence of

  3. The effects of flagellar hook compliance on motility of monotrichous bacteria: A modeling study

    NASA Astrophysics Data System (ADS)

    Shum, H.; Gaffney, E. A.

    2012-06-01

    A crucial structure in the motility of flagellated bacteria is the hook, which connects the flagellum filament to the motor in the cell body. Early mathematical models of swimming bacteria assume that the helically shaped flagellum rotates rigidly about its axis, which coincides with the axis of the cell body. Motivated by evidence that the hook is much more flexible than the rest of the flagellum, we develop a new model that allows a naturally straight hook to bend. Hook dynamics are based on the Kirchhoff rod model, which is combined with a boundary element method for solving viscous interactions between the bacterium and the surrounding fluid. For swimming in unbounded fluid, we find good support for using a rigid model since the hook reaches an equilibrium configuration within several revolutions of the motor. However, for effective swimming, there are constraints on the hook stiffness relative to the scale set by the product of the motor torque with the hook length. When the hook is too flexible, its shape cannot be maintained and large deformations and stresses build up. When the hook is too rigid, the flagellum does not align with the cell body axis and the cell "wobbles" with little net forward motion. We also examine the attraction of swimmers to no-slip surfaces and find that the tendency to swim steadily close to a surface can be very sensitive to the combination of the hook rigidity and the precise shape of the cell and flagellum.

  4. The extended AT-hook is a novel RNA binding motif.

    PubMed

    Filarsky, Michael; Zillner, Karina; Araya, Ingrid; Villar-Garea, Ana; Merkl, Rainer; Längst, Gernot; Németh, Attila

    2015-01-01

    The AT-hook has been defined as a DNA binding peptide motif that contains a glycine-arginine-proline (G-R-P) tripeptide core flanked by basic amino acids. Recent reports documented variations in the sequence of AT-hooks and revealed RNA binding activity of some canonical AT-hooks, suggesting a higher structural and functional variability of this protein domain than previously anticipated. Here we describe the discovery and characterization of the extended AT-hook peptide motif (eAT-hook), in which basic amino acids appear symmetrical mainly at a distance of 12-15 amino acids from the G-R-P core. We identified 80 human and 60 mouse eAT-hook proteins and biochemically characterized the eAT-hooks of Tip5/BAZ2A, PTOV1 and GPBP1. Microscale thermophoresis and electrophoretic mobility shift assays reveal the nucleic acid binding features of this peptide motif, and show that eAT-hooks bind RNA with one order of magnitude higher affinity than DNA. In addition, cellular localization studies suggest a role for the N-terminal eAT-hook of PTOV1 in nucleocytoplasmic shuttling. In summary, our findings classify the eAT-hook as a novel nucleic acid binding motif, which potentially mediates various RNA-dependent cellular processes.

  5. On the reliability of hook echoes as tornado indicators

    NASA Technical Reports Server (NTRS)

    Forbes, G. S.

    1981-01-01

    A study of radar echoes associated with the tornadoes of the 3 April 1974 outbreak was performed to evaluate the usefulness of echo shape as an indicator of tornadic thunderstorms. The hook shape was usually successful in characterizing an echo as tornadic, with a false alarm rate of 16%. Because hook echoes were relatively rare, however, a less restrictive shape called distinctive was more successful at detecting tornadic thunderstorms, identifying 65% of the tornadic echoes. An echo had a distinctive shape if it possessed a marked appendage on its right rear flank or was in the shape of a spiral, comma or line echo wave pattern (LEWP). Characteristics of the distinctive echo are given.

  6. Quantitative guidelines for force calibration through spectral analysis of magnetic tweezers data.

    PubMed

    te Velthuis, Aartjan J W; Kerssemakers, Jacob W J; Lipfert, Jan; Dekker, Nynke H

    2010-08-09

    Single-molecule techniques are powerful tools that can be used to study the kinetics and mechanics of a variety of enzymes and their complexes. Force spectroscopy, for example, can be used to control the force applied to a single molecule and thereby facilitate the investigation of real-time nucleic acid-protein interactions. In magnetic tweezers, which offer straightforward control and compatibility with fluorescence measurements or parallel tracking modes, force-measurement typically relies on the analysis of positional fluctuations through video microscopy. Significant errors in force estimates, however, may arise from incorrect spectral analysis of the Brownian motion in the magnetic tweezers. Here we investigated physical and analytical optimization procedures that can be used to improve the range over which forces can be reliably measured. To systematically probe the limitations of magnetic tweezers spectral analysis, we have developed a magnetic tweezers simulator, whose outcome was validated with experimental data. Using this simulator, we evaluate methods to correctly perform force experiments and provide guidelines for correct force calibration under configurations that can be encountered in typical magnetic tweezers experiments.

  7. Bulky melamine-based Zn-porphyrin tweezer as a CD probe of molecular chirality.

    PubMed

    Petrovic, Ana G; Vantomme, Ghislaine; Negrón-Abril, Yashira L; Lubian, Elisa; Saielli, Giacomo; Menegazzo, Ileana; Cordero, Roselynn; Proni, Gloria; Nakanishi, Koji; Carofiglio, Tommaso; Berova, Nina

    2011-10-01

    The transfer of chirality from a guest molecule to an achiral host is the subject of significant interest especially when, upon chiral induction, the chiroptical response of the host/guest complex can effectively report the absolute configuration (AC) of the guest. For more than a decade, dimeric metalloporphyrin hosts (tweezers) have been successfully applied as chirality probes for determination of the AC for a wide variety of chiral synthetic compounds and natural products. The objective of this study is to investigate the utility of a new class of melamine-bridged Zn-porphyrin tweezers as sensitive AC reporters. A combined approach based on an experimental CD analysis and a theoretical prediction of the prevailing interporphyrin helicity demonstrates that these tweezers display favorable properties for chiral recognition. Herein, we discuss the application of the melamine-bridged tweezer to the chiral recognition of a diverse set of chiral guests, such as 1,2-diamines, α-amino-esters and amides, secondary alcohols, and 1,2-amino-alcohols. The bulky periphery and the presence of a rigid porphyrin linkage lead, in some cases, to a more enhanced CD sensitivity than that reported earlier with other tweezers.

  8. Automatic real time evaluation of red blood cell elasticity by optical tweezers

    NASA Astrophysics Data System (ADS)

    Moura, Diógenes S.; Silva, Diego C. N.; Williams, Ajoke J.; Bezerra, Marcos A. C.; Fontes, Adriana; de Araujo, Renato E.

    2015-05-01

    Optical tweezers have been used to trap, manipulate, and measure individual cell properties. In this work, we show that the association of a computer controlled optical tweezers system with image processing techniques allows rapid and reproducible evaluation of cell deformability. In particular, the deformability of red blood cells (RBCs) plays a key role in the transport of oxygen through the blood microcirculation. The automatic measurement processes consisted of three steps: acquisition, segmentation of images, and measurement of the elasticity of the cells. An optical tweezers system was setup on an upright microscope equipped with a CCD camera and a motorized XYZ stage, computer controlled by a Labview platform. On the optical tweezers setup, the deformation of the captured RBC was obtained by moving the motorized stage. The automatic real-time homemade system was evaluated by measuring RBCs elasticity from normal donors and patients with sickle cell anemia. Approximately 150 erythrocytes were examined, and the elasticity values obtained by using the developed system were compared to the values measured by two experts. With the automatic system, there was a significant time reduction (60 × ) of the erythrocytes elasticity evaluation. Automated system can help to expand the applications of optical tweezers in hematology and hemotherapy.

  9. Numerical study of the properties of optical vortex array laser tweezers.

    PubMed

    Kuo, Chun-Fu; Chu, Shu-Chun

    2013-11-04

    Chu et al. constructed a kind of Ince-Gaussian modes (IGM)-based vortex array laser beams consisting of p x p embedded optical vortexes from Ince-Gaussian modes, IG(e)(p,p) modes [Opt. Express 16, 19934 (2008)]. Such an IGM-based vortex array laser beams maintains its vortex array profile during both propagation and focusing, and is applicable to optical tweezers. This study uses the discrete dipole approximation (DDA) method to study the properties of the IGM-based vortex array laser tweezers while it traps dielectric particles. This study calculates the resultant force exerted on the spherical dielectric particles of different sizes situated at the IGM-based vortex array laser beam waist. Numerical results show that the number of trapping spots of a structure light (i.e. IGM-based vortex laser beam), is depended on the relation between the trapped particle size and the structure light beam size. While the trapped particle is small comparing to the beam size of the IGM-based vortex array laser beams, the IGM-based vortex array laser beams tweezers are suitable for multiple traps. Conversely, the tweezers is suitable for single traps. The results of this study is useful to the future development of the vortex array laser tweezers applications.

  10. Learning From Experience: Development of a Cognitive Task List to Perform a Safe and Successful Non-Rotational Forceps Delivery.

    PubMed

    Simpson, Andrea N; Gurau, David; Secter, Michael; Mocarski, Eva; Pittini, Richard; Snelgrove, John; Hodges, Ryan; Windrim, Rory; Higgins, Mary

    2015-07-01

    Objectif : La hausse des taux d’accouchement par césarienne a entraîné une baisse des taux d’accouchement instrumental. Cette situation a donné lieu à un nouveau défi sur le plan pédagogique en ce qui concerne l’enseignement et l’acquisition de compétences. Dans le cadre de l’enseignement offert aux stagiaires, certaines tâches menées par le subconscient pourraient passer inaperçues (car elles sont automatiques) et donc ne pas être abordées par le personnel de supervision. Cette étude avait pour but de créer un nouvel outil pour relever ce défi : identifier les étapes de base requises pour la réussite d’un accouchement par forceps non rotationnels en toute sûreté. Méthodes : Les membres du personnel infirmier de la salle de travail et d’accouchement de trois hôpitaux universitaires d’envergure ont identifié les cliniciens qu’ils considéraient comme étant particulièrement compétents en matière d’accouchements par forceps non rotationnels. Les obstétriciens dont les noms revenaient les plus souvent ont été conviés à participer à l’étude. Après avoir offert leur consentement par écrit, les participants ont été filmés pendant l’exécution d’un accouchement par forceps non rotationnels sur un modèle. Deux cliniciens ont passé en revue toutes les vidéos et ont documenté toutes les composantes verbales et non verbales de l’évaluation. Une analyse thématique a combiné les résultats en un résumé intégré. Le résumé initial a par la suite été distribué aux participants pour que l’on obtienne leur approbation. Résultats : Dix-sept cliniciens ont ainsi été identifiés et ont consenti à participer à l’étude. Les thèmes identifiés ont été les suivants : la nécessité de procéder à une évaluation rigoureuse de l’admissibilité de la patiente à un accouchement opératoire, le rôle de l’équipe multidisciplinaire, la nécessité d’une communication rigoureuse et adapt

  11. Studying Hooke's Law by Using a Pogo Stick

    ERIC Educational Resources Information Center

    Silva, Nicolas

    2011-01-01

    Perhaps the pogo stick was little Robert Hooke's favorite childhood toy, consisting of a stiff spring inserted in a tube fixed at the upper end and connected to a moveable rod at the other. Hand grips and a foot rest are connected to the tube. The idea is to jump on it taking advantage of the force provided by the spring when it is compressed.…

  12. Probing DNA helicase kinetics with temperature-controlled magnetic tweezers.

    PubMed

    Gollnick, Benjamin; Carrasco, Carolina; Zuttion, Francesca; Gilhooly, Neville S; Dillingham, Mark S; Moreno-Herrero, Fernando

    2015-03-18

    Motor protein functions like adenosine triphosphate (ATP) hydrolysis or translocation along molecular substrates take place at nanometric scales and consequently depend on the amount of available thermal energy. The associated rates can hence be investigated by actively varying the temperature conditions. In this article, a thermally controlled magnetic tweezers (MT) system for single-molecule experiments at up to 40 °C is presented. Its compact thermostat module yields a precision of 0.1 °C and can in principle be tailored to any other surface-coupled microscopy technique, such as tethered particle motion (TPM), nanopore-based sensing of biomolecules, or super-resolution fluorescence imaging. The instrument is used to examine the temperature dependence of translocation along double-stranded (ds)DNA by individual copies of the protein complex AddAB, a helicase-nuclease motor involved in dsDNA break repair. Despite moderately lower mean velocities measured at sub-saturating ATP concentrations, almost identical estimates of the enzymatic reaction barrier (around 21-24 k(B)T) are obtained by comparing results from MT and stopped-flow bulk assays. Single-molecule rates approach ensemble values at optimized chemical energy conditions near the motor, which can withstand opposing loads of up to 14 piconewtons (pN). Having proven its reliability, the temperature-controlled MT described herein will eventually represent a routinely applied method within the toolbox for nano-biotechnology.

  13. Improved antireflection coated microspheres for biological applications of optical tweezers

    NASA Astrophysics Data System (ADS)

    Ferro, Valentina; Sonnberger, Aaron; Abdosamadi, Mohammad K.; McDonald, Craig; Schäffer, Erik; McGloin, David

    2016-09-01

    The success of optical tweezers in cellular biology1 is in part due to the wide range of forces that can be applied, from femto- to hundreds of pico-Newtons; nevertheless extending the range of applicable forces to the nanoNewton regime opens access to a new set of phenomena that currently lie beyond optical manipulation. A successful approach to overcome the conventional limits on trapping forces involves the optimization of the trapped probes. Jannasch et al.2 demonstrated that an anti-reflective shell of nanoporous titanium dioxide (aTiO2, nshell = 1.75) on a core particle made out of titanium dioxide in the anatase phase (cTiO2, ncore = 2.3) results in trappable microspheres capable to reach forces above 1 nN. Here we present how the technique can be further improved by coating the high refractive index microspheres with an additional anti-reflective shell made out of silica (SiO2). This external shell not only improves the trap stability for microspheres of different sizes, but also enables the use of functionalization techniques already established for commercial silica beads in biological experiments. We are also investigating the use of these new microspheres as probes to measure adhesion forces between intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 1 (LFA-1) in effector T-Cells and will present preliminary results comparing standard and high-index beads.

  14. A holographic optical tweezers module for the International Space Station

    NASA Astrophysics Data System (ADS)

    Shane, J.; Serati, R.; Masterson, H.; Serati, Steve

    2016-09-01

    The International Space Station (ISS) is an unparalleled laboratory for studying colloidal suspensions in microgravity. The first colloidal experiments on the ISS involved passive observation of suspended particles, and current experiments are now capable of observation under controlled environmental conditions; for example, under heating or under externally applied magnetic or electric fields. Here, we describe the design of a holographic optical tweezers (HOT) module for the ISS, with the goal of giving ISS researchers the ability to actively control 3D arrangements of particles, allowing them to initialize and perform repeatable experiments. We discuss the design's modifications to the basic HOT module hardware to allow for operation in a high-vibration, microgravity environment. We also discuss the module's planned particle tracking and routing capabilities, which will enable the module to remotely perform pre-programmed colloidal and biological experiments. The HOT module's capabilities can be expanded or upgraded through software alone, providing a unique platform for optical trapping researchers to test new tweezing beam configurations and routines in microgravity.

  15. Application of laser tweezers to passive microrheology of collagen solutions

    NASA Astrophysics Data System (ADS)

    Shayegan, Marjan; Forde, Nancy R.

    2009-05-01

    Rheology is the field that can describe both viscous and elastic properties of a material in response to applied force or deformation. Passive microrheology (PMR) is a technique in which motion of a particle arising from thermal fluctuations is measured on nanometer length scales. One experimental approach to PMR uses optical tweezers, which trap and probe μm-sized particles, located within the material, at a high bandwidth. In this study, viscoelastic properties of solutions of collagen are characterized. To do this, we have probed the power spectral density of fluctuations of 1-μm-diameter microspheres optically trapped in acidic solutions of varying concentration of collagen type I (0, 0.5, and 1 mg/ml). The results show evidence that the behaviour of the solutions becomes increasingly non-Newtonian at high protein concentration. We attribute this to the presence of the viscoelastic polymer. This introduces frequency dependence to the complex modulus of the solution which is used to characterize the elasticity and viscosity of these systems.

  16. Use of shape induced birefringence for rotation in optical tweezers

    NASA Astrophysics Data System (ADS)

    Asavei, Theodor; Nieminen, Timo A.; Heckenberg, Norman R.; Rubinsztein-Dunlop, Halina

    2010-08-01

    Since a light beam can carry angular momentum (AM) it is possible to use optical tweezers to exert torques to twist or rotate microscopic objects. The alignment torque exerted on an elongated particle in a polarized light field represents a possible torque mechanism. In this situation, although some exchange of orbital angular momentum occurs, scattering calculations show that spin dominates, and polarization measurements allow the torque to be measured with good accuracy. This phenomenon can be explained by considering shape birefringence with an induced polarizability tensor. Another example of a shape birefringent object is a microsphere with a cylindrical cavity. Its design is based on the fact that due to its symmetry a sphere does not rotate in an optical trap, but one could break the symmetry by designing an object with a spherical outer shape with a non spherical cavity inside. The production of such a structure can be achieved using a two photon photo-polymerization technique. We show that using this technique, hollow spheres with varying sizes of the cavity can be successfully constructed. We have been able to demonstrate rotation of these spheres with cylindrical cavities when they are trapped in a laser beam carrying spin angular momentum. The torque efficiency achievable in this system can be quantified as a function of a cylinder diameter. Because they are biocompatible and easily functionalized, these structures could be very useful in work involving manipulation, control and probing of individual biological molecules and molecular motors.

  17. Bio-syncretic tweezers actuated by microorganisms: modeling and analysis.

    PubMed

    Zhang, C; Xie, S X; Wang, W X; Xi, N; Wang, Y C; Liu, L Q

    2016-09-28

    Advancements in micro-/nano-technology have led to the development of micro-manipulators. However, some challenges remain; for instance, the efficiency, precision and flexibility of micro-manipulators restrain their applications. This paper proposes a bio-tweezer system to flexibly manipulate micro-objects with bio-actuation via local light-induced high-concentration microorganisms in two different manipulation modes: light-spot induced mode and geometric shape-induced mode. Depending on the shape of micro-objects, either 2-dimensional translation or 1-dimensional rotation can be achieved. Based on the Langevin equation, a mathematical model considering both hydrodynamics and mimicked Brownian motion is proposed to analyze the bio-manipulation performance of the microorganisms; the model was validated by experiments to translate micro-particles in a two-dimensional plane and to rotate a micro-gear structure around its axis. This paper will aid in the development of micro-manipulators and the quantitative understanding of micro-/nano-manipulation actuated by microorganisms.

  18. Magnetic tweezers force calibration for molecules that exhibit conformational switching

    NASA Astrophysics Data System (ADS)

    Jacobson, David R.; Saleh, Omar A.

    2016-09-01

    High spatial and temporal resolution magnetic tweezers experiments allow for the direct calibration of pulling forces applied to short biomolecules. In one class of experiments, a force is applied to a structured RNA or protein to induce an unfolding transition; when the force is maintained at particular values, the molecule can exhibit conformational switching between the folded and unfolded states or between intermediate states. Here, we analyze the degree to which common force calibration approaches, involving the fitting of model functions to the Allan variance or power spectral density of the bead trajectory, are biased by this conformational switching. We find significant effects in two limits: that of large molecular extension changes between the two states, in which alternative fitting functions must be used, and that of very fast switching kinetics, in which the force calibration cannot be recovered due to the slow diffusion time of the magnetic bead. We use simulations and high-resolution RNA hairpin data to show that most biophysical experiments do not occur in either of these limits.

  19. Probing DNA Helicase Kinetics with Temperature‐Controlled Magnetic Tweezers

    PubMed Central

    Gollnick, Benjamin; Carrasco, Carolina; Zuttion, Francesca; Gilhooly, Neville S.; Dillingham, Mark S.

    2015-01-01

    Motor protein functions like adenosine triphosphate (ATP) hydrolysis or translocation along molecular substrates take place at nanometric scales and consequently depend on the amount of available thermal energy. The associated rates can hence be investigated by actively varying the temperature conditions. In this article, a thermally controlled magnetic tweezers (MT) system for single‐molecule experiments at up to 40 °C is presented. Its compact thermostat module yields a precision of 0.1 °C and can in principle be tailored to any other surface‐coupled microscopy technique, such as tethered particle motion (TPM), nanopore‐based sensing of biomolecules, or super‐resolution fluorescence imaging. The instrument is used to examine the temperature dependence of translocation along double‐stranded (ds)DNA by individual copies of the protein complex AddAB, a helicase‐nuclease motor involved in dsDNA break repair. Despite moderately lower mean velocities measured at sub‐saturating ATP concentrations, almost identical estimates of the enzymatic reaction barrier (around 21–24 k B T) are obtained by comparing results from MT and stopped‐flow bulk assays. Single‐molecule rates approach ensemble values at optimized chemical energy conditions near the motor, which can withstand opposing loads of up to 14 piconewtons (pN). Having proven its reliability, the temperature‐controlled MT described herein will eventually represent a routinely applied method within the toolbox for nano‐biotechnology. PMID:25400244

  20. Particle interaction measurements using laser tweezers optical trapping.

    SciTech Connect

    Koehler, Timothy P.; Brinker, C. Jeffrey; Brotherton, Christopher M.; Grillet, Anne M.; Molecke, Ryan A.

    2008-08-01

    Laser tweezers optical trapping provides a unique noninvasive capability to trap and manipulate particles in solution at the focal point of a laser beam passed through a microscope objective. Additionally, combined with image analysis, interaction forces between colloidal particles can be quantitatively measured. By looking at the displacement of particles within the laser trap due to the presence of a neighboring particle or looking at the relative diffusion of two particles held near each other by optical traps, interparticle interaction forces ranging from pico- to femto-Newtons can be measured. Understanding interaction forces is critical for predicting the behavior of particle dispersions including dispersion stability and flow rheology. Using a new analysis method proposed by Sainis, Germain, and Dufresne, we can simultaneously calculate the interparticle velocity and particle diffusivity which allows direct calculation of the interparticle potential for the particles. By applying this versatile tool, we measure difference in interactions between various phospholipid bilayers that have been coated onto silica spheres as a new type of solid supported liposome. We measure bilayer interactions of several cell membrane lipids under various environmental conditions such as pH and ionic strength and compare the results with those obtained for empty liposomes. These results provide insight into the role of bilayer fluctuations in liposome fusion, which is of fundamental interest to liposome based drug delivery schemes.

  1. Temperature control and measurement with tunable femtosecond optical tweezers

    NASA Astrophysics Data System (ADS)

    Mondal, Dipankar; Goswami, Debabrata

    2016-09-01

    We present the effects of wavelength dependent temperature rise in a femtosecond optical tweezers. Our experiments involve the femtosecond trapping laser tunable from 740-820 nm at low power 25 mW to cause heating in the trapped volume within a homogeneous solution of sub micro-molar concentration of IR dye. The 780 nm high repetition rate laser acts as a resonant excitation source which helps to create the local heating effortlessly within the trapping volume. We have used both position autocorrelation and equipartion theorem to evaluate temperature at different wavelength having different absorption coefficient. Fixing the pulse width in the temporal domain gives constant bandwidth at spatial domain, which makes our system behave as a tunable temperature rise device with high precision. This observation leads us to calculate temperature as well as viscosity within the vicinity of the trapping zone. A mutual energy transfer occurs between the trapped bead and solvents that leads to transfer the thermal energy of solvents into the kinetic energy of the trap bead and vice-versa. Thus hot solvated molecules resulting from resonant and near resonant excitation of trapping wavelength can continuously dissipate heat to the trapped bead which will be reflected on frequency spectrum of Brownian noise exhibited by the bead. Temperature rise near the trapping zone can significantly change the viscosity of the medium. We observe temperature rise profile according to its Gaussian shaped absorption spectrum with different wavelength.

  2. Manipulating and assembling metallic beads with Optoelectronic Tweezers

    NASA Astrophysics Data System (ADS)

    Zhang, Shuailong; Juvert, Joan; Cooper, Jonathan M.; Neale, Steven L.

    2016-09-01

    Optoelectronic tweezers (OET) or light-patterned dielectrophoresis (DEP) has been developed as a micromanipulation technology for controlling micro- and nano-particles with applications such as cell sorting and studying cell communications. Additionally, the capability of moving small objects accurately and assembling them into arbitrary 2D patterns also makes OET an attractive technology for microfabrication applications. In this work, we demonstrated the use of OET to manipulate conductive silver-coated Poly(methyl methacrylate) (PMMA) microspheres (50 μm diameter) into tailored patterns. It was found that the microspheres could be moved at a max velocity of 3200 μm/s, corresponding to 4.2 nano-newton (10‑9 N) DEP force, and also could be positioned with high accuracy via this DEP force. The underlying mechanism for this strong DEP force is shown by our simulations to be caused by a significant increase of the electric field close to the particles, due to the interaction between the field and the silver shells coating the microspheres. The associated increase in electrical gradient causes DEP forces that are much stronger than any previously reported for an OET device, which facilitates manipulation of the metallic microspheres efficiently without compromise in positioning accuracy and is important for applications on electronic component assembling and circuit construction.

  3. Membrane tether formation from outer hair cells with optical tweezers.

    PubMed Central

    Li, Zhiwei; Anvari, Bahman; Takashima, Masayoshi; Brecht, Peter; Torres, Jorge H; Brownell, William E

    2002-01-01

    Optical tweezers were used to characterize the mechanical properties of the outer hair cell (OHC) plasma membrane by pulling tethers with 4.5-microm polystyrene beads. Tether formation force and tether force were measured in static and dynamic conditions. A greater force was required for tether formations from OHC lateral wall (499 +/- 152 pN) than from OHC basal end (142 +/- 49 pN). The difference in the force required to pull tethers is consistent with an extensive cytoskeletal framework associated with the lateral wall known as the cortical lattice. The apparent plasma membrane stiffness, estimated under the static conditions by measuring tether force at different tether length, was 3.71 pN/microm for OHC lateral wall and 4.57 pN/microm for OHC basal end. The effective membrane viscosity was measured by pulling tethers at different rates while continuously recording the tether force, and estimated in the range of 2.39 to 5.25 pN x s/microm. The viscous force most likely results from the viscous interactions between plasma membrane lipids and the OHC cortical lattice and/or integral membrane proteins. The information these studies provide on the mechanical properties of the OHC lateral wall is important for understanding the mechanism of OHC electromotility. PMID:11867454

  4. Manipulating and assembling metallic beads with Optoelectronic Tweezers

    PubMed Central

    Zhang, Shuailong; Juvert, Joan; Cooper, Jonathan M.; Neale, Steven L.

    2016-01-01

    Optoelectronic tweezers (OET) or light-patterned dielectrophoresis (DEP) has been developed as a micromanipulation technology for controlling micro- and nano-particles with applications such as cell sorting and studying cell communications. Additionally, the capability of moving small objects accurately and assembling them into arbitrary 2D patterns also makes OET an attractive technology for microfabrication applications. In this work, we demonstrated the use of OET to manipulate conductive silver-coated Poly(methyl methacrylate) (PMMA) microspheres (50 μm diameter) into tailored patterns. It was found that the microspheres could be moved at a max velocity of 3200 μm/s, corresponding to 4.2 nano-newton (10−9 N) DEP force, and also could be positioned with high accuracy via this DEP force. The underlying mechanism for this strong DEP force is shown by our simulations to be caused by a significant increase of the electric field close to the particles, due to the interaction between the field and the silver shells coating the microspheres. The associated increase in electrical gradient causes DEP forces that are much stronger than any previously reported for an OET device, which facilitates manipulation of the metallic microspheres efficiently without compromise in positioning accuracy and is important for applications on electronic component assembling and circuit construction. PMID:27599445

  5. Toward automated formation of microsphere arrangements using multiplexed optical tweezers

    NASA Astrophysics Data System (ADS)

    Rajasekaran, Keshav; Bollavaram, Manasa; Banerjee, Ashis G.

    2016-09-01

    Optical tweezers offer certain advantages such as multiplexing using a programmable spatial light modulator, flexibility in the choice of the manipulated object and the manipulation medium, precise control, easy object release, and minimal object damage. However, automated manipulation of multiple objects in parallel, which is essential for efficient and reliable formation of micro-scale assembly structures, poses a difficult challenge. There are two primary research issues in addressing this challenge. First, the presence of stochastic Langevin force giving rise to Brownian motion requires motion control for all the manipulated objects at fast rates of several Hz. Second, the object dynamics is non-linear and even difficult to represent analytically due to the interaction of multiple optical traps that are manipulating neighboring objects. As a result, automated controllers have not been realized for tens of objects, particularly with three dimensional motions with guaranteed collision avoidances. In this paper, we model the effect of interacting optical traps on microspheres with significant Brownian motions in stationary fluid media, and develop simplified state-space representations. These representations are used to design a model predictive controller to coordinate the motions of several spheres in real time. Preliminary experiments demonstrate the utility of the controller in automatically forming desired arrangements of varying configurations starting with randomly dispersed microspheres.

  6. Optical tweezers as manufacturing and characterization tool in microfluidics

    NASA Astrophysics Data System (ADS)

    Köhler, J.; Ghadiri, R.; Ksouri, S. I.; Gurevich, E. L.; Ostendorf, A.

    2014-09-01

    Pumping and mixing of small volumes of liquid samples are basic processes in microfluidic applications. Among the number of different principles for active transportation of the fluids microrotors have been investigated from the beginning. The main challenge in microrotors, however, has been the driving principle. In this work a new approach for a very simple magnetic driving principle has been realized. More precisely, we take advantage of optical grippers to fabricate various microrotors and introduce an optical force method to characterize the fluid flow generated by rotating the structures through magnetic actuation. The microrotors are built of silica and magnetic microspheres which are initially coated with Streptavidin or Biotin molecules. Holographic optical tweezers (HOT) are used to trap, to position, and to assemble the microspheres with the chemical interaction of the biomolecules leading to a stable binding. Using this technique, complex designs of microrotors can be realized. The magnetic response of the magnetic microspheres enables the rotation and control of the structures through an external magnetic field. The generated fluid flow around the microrotor is measured optically by inserting a probe particle next to the rotor. While the probe particle is trapped by optical forces the flow force leads to a displacement of the particle from the trapping position. This displacement is directly related to the flow velocity and can be measured and calibrated. Variations of the microrotor design and rotating speed lead to characteristic flow fields.

  7. Calibration of holographic optical tweezers for force measurements on biomaterials

    NASA Astrophysics Data System (ADS)

    van der Horst, Astrid; Forde, Nancy

    2009-05-01

    Holographic optical tweezers (HOTs) modify the phase of a laser beam to create and dynamically position multiple optical traps independently in 3D; refractive micrometer-sized particles can be held in these traps to function as probing handles. HOTs offer the flexibility needed to probe the mechanics of complex systems such as cells or protein networks. Thus far, however, HOTs have not found wide use in biophysics, in large part due to lack of evidence as to how exerted forces vary as the positions of HOT traps are changed. To perform quantitative force measurements, parameters such as trap stiffness, range of trap steering, and minimum step size are of key importance. We find for our HOT setup that stiffness does not change significantly over a range of ˜25μm. In addition, we control and detect, using high-speed (>kHz) camera imaging, trap displacements to ˜1nm. Our results suggest that after full characterization HOTs can be successfully employed in quantitative experiments on biomaterials, e.g., probing elastomeric properties of structural protein networks.

  8. Triaxial Atomic Force Microscope Contact-Free Tweezers for Nanoassembly

    PubMed Central

    Brown, Keith A; Westervelt, Robert M

    2010-01-01

    We propose a Traixial Atomic Force Microscope (AFM) Contact-free Tweezer (TACT) for the controlled assembly of nanoparticles suspended in a liquid. The TACT overcomes four major challenges faced in nanoassembly: (1) The TACT can hold and position a single nanoparticle with spatial accuracy smaller than the nanoparticle size (~ 5 nm). (2) The nanoparticle is held away from the surface of the TACT by negative dielectrophoresis (nDEP) to prevent van der Waals forces from sticking it to the TACT. (3) The TACT holds nanoparticles in a trap that is size-matched to the particle and surrounded by a repulsive region so that it will only trap a single particle at a time. (4) The trap can hold a semiconductor nanoparticle in water with a trapping energy greater than thermal energy. For example, a 5 nm radius silicon nanoparticle is held with 10 kBT at room temperature. We propose methods for using the TACT as a nanoscale pick-and-place tool to assemble semiconductor quantum dots, biological molecules, semiconductor nanowires, and carbon nanotubes. PMID:19713582

  9. Calibration of femtosecond optical tweezers as a sensitive thermometer

    NASA Astrophysics Data System (ADS)

    Mondal, Dipankar; Goswami, Debabrata

    2015-08-01

    We present cumulative perturbation effects of femtosecond laser pulses on an optical tweezer. Our experiments involve a dual wavelength high repetition rate femtosecond laser, one at the non-heating wavelength of 780 nm while the other at 1560 nm to cause heating in the trapped volume under low power (100-800 μW) conditions. The 1560 nm high repetition rate laser acts as a resonant excitation source for the vibrational combination band of the hydroxyl group (OH) of water, which helps create the local heating effortlessly within the trapping volume. With such an experimental system, we are the first to observe direct effect of temperature on the corner frequency deduced from power spectrum. We can, thus, control and measure temperature precisely at the optical trap. This observation has lead us to calculate viscosity as well as temperature in the vicinity of the trapping zone. These experimental results also support the well-known fact that the nature of Brownian motion is the response of the optically trapped bead from the temperature change of surroundings. Temperature rise near the trapping zone can significantly change the viscosity of the medium. However, we notice that though the temperature and viscosity are changing as per our corner frequency calculations, the trap stiffness remains the same throughout our experiments within the temperature range of about 20 K.

  10. Hooking up and penetrative hookups: correlates that differentiate college men.

    PubMed

    Olmstead, Spencer B; Pasley, Kay; Fincham, Frank D

    2013-05-01

    One prominent pathway to sexual intimacy among college student populations is hooking up. Past research has largely compared men and women, with limited attention given to how men differ regarding involvement in hookups and their hookup behaviors. This study used a sample of 412 college men to examine the individual, social, relational, and family background correlates of (1) hooking up during a semester and (2) penetrative hookup encounters (e.g., oral sex, intercourse). Overall, 69% reported a hookup during the semester, with 73% of those who hooked up reporting penetrative hookups. Using logistic regression, men were more likely to hookup if they had an extraverted personality, were consuming more alcohol, and had previous hookup experience. They were less likely to hookup if they were more thoughtful about their relationship decisions and if they were in a stable, committed romantic relationship. Men also were more likely to engage in penetrative hookups only if they held more permissive attitudes towards sex and if they had previous penetrative hookup experience. Implications for intervention and research are discussed.

  11. Fracture of the hook of the hamate in athletes.

    PubMed

    Stark, H H; Jobe, F W; Boyes, J H; Ashworth, C R

    1977-07-01

    During an eight-year period, four tennis players, seven golfers, and nine baseball players were seen with a fracture of the hook of the hamate. Eighteen of these twenty patients were disabled by pain and after the fracture fragment was removed, all eighteen were relieved so that they returned to their athletic pursuits. Two patients were asymptomatic, their old fracture being discovered accidentally when they were treated for other injuries. Nineteen of the twenty patients had been examined before coming under our care, but the correct diagnosis had been made in only two. Conservative treatment, including rest, physical therapy, and injections of steroids into the wrist and hand, had not been beneficial. From the history and findings, we believe that these fractures were caused by a direct blow against the hook of the hamate caused by the handle of the tennis racket, golf club, or bat during a swing, and not by indirect force produced by the ligaments and muscles attached to the hook. The fracture was demonstrated in all twenty patients by a roentgenogram (profile view) of the carpal tunnel.

  12. Fiber based optical tweezers for simultaneous in situ force exertion and measurements in a 3D polyacrylamide gel compartment.

    PubMed

    Ti, Chaoyang; Thomas, Gawain M; Ren, Yundong; Zhang, Rui; Wen, Qi; Liu, Yuxiang

    2015-07-01

    Optical tweezers play an important role in biological applications. However, it is difficult for traditional optical tweezers based on objective lenses to work in a three-dimensional (3D) solid far away from the substrate. In this work, we develop a fiber based optical trapping system, namely inclined dual fiber optical tweezers, that can simultaneously apply and measure forces both in water and in a 3D polyacrylamide gel matrix. In addition, we demonstrate in situ, non-invasive characterization of local mechanical properties of polyacrylamide gel by measurements on an embedded bead. The fiber optical tweezers measurements agree well with those of atomic force microscopy (AFM). The inclined dual fiber optical tweezers provide a promising and versatile tool for cell mechanics study in 3D environments.

  13. Thermal gradient induced tweezers for the manipulation of particles and cells

    NASA Astrophysics Data System (ADS)

    Chen, Jiajie; Cong, Hengji; Loo, Fong-Chuen; Kang, Zhiwen; Tang, Minghui; Zhang, Haixi; Wu, Shu-Yuen; Kong, Siu-Kai; Ho, Ho-Pui

    2016-11-01

    Optical tweezers are a well-established tool for manipulating small objects. However, their integration with microfluidic devices often requires an objective lens. More importantly, trapping of non-transparent or optically sensitive targets is particularly challenging for optical tweezers. Here, for the first time, we present a photon-free trapping technique based on electro-thermally induced forces. We demonstrate that thermal-gradient-induced thermophoresis and thermal convection can lead to trapping of polystyrene spheres and live cells. While the subject of thermophoresis, particularly in the micro- and nano-scale, still remains to be fully explored, our experimental results have provided a reasonable explanation for the trapping effect. The so-called thermal tweezers, which can be readily fabricated by femtosecond laser writing, operate with low input power density and are highly versatile in terms of device configuration, thus rendering high potential for integration with microfluidic devices as well as lab-on-a-chip systems.

  14. Thermal gradient induced tweezers for the manipulation of particles and cells

    PubMed Central

    Chen, Jiajie; Cong, Hengji; Loo, Fong-Chuen; Kang, Zhiwen; Tang, Minghui; Zhang, Haixi; Wu, Shu-Yuen; Kong, Siu-Kai; Ho, Ho-Pui

    2016-01-01

    Optical tweezers are a well-established tool for manipulating small objects. However, their integration with microfluidic devices often requires an objective lens. More importantly, trapping of non-transparent or optically sensitive targets is particularly challenging for optical tweezers. Here, for the first time, we present a photon-free trapping technique based on electro-thermally induced forces. We demonstrate that thermal-gradient-induced thermophoresis and thermal convection can lead to trapping of polystyrene spheres and live cells. While the subject of thermophoresis, particularly in the micro- and nano-scale, still remains to be fully explored, our experimental results have provided a reasonable explanation for the trapping effect. The so-called thermal tweezers, which can be readily fabricated by femtosecond laser writing, operate with low input power density and are highly versatile in terms of device configuration, thus rendering high potential for integration with microfluidic devices as well as lab-on-a-chip systems. PMID:27853191

  15. Manipulation of cells with laser microbeam scissors and optical tweezers: a review

    NASA Astrophysics Data System (ADS)

    Greulich, Karl Otto

    2017-02-01

    The use of laser microbeams and optical tweezers in a wide field of biological applications from genomic to immunology is discussed. Microperforation is used to introduce a well-defined amount of molecules into cells for genetic engineering and optical imaging. The microwelding of two cells induced by a laser microbeam combines their genetic outfit. Microdissection allows specific regions of genomes to be isolated from a whole set of chromosomes. Handling the cells with optical tweezers supports investigation on the attack of immune systems against diseased or cancerous cells. With the help of laser microbeams, heart infarction can be simulated, and optical tweezers support studies on the heartbeat. Finally, laser microbeams are used to induce DNA damage in living cells for studies on cancer and ageing.

  16. Optical disassembly of cellular clusters by tunable ‘tug-of-war’ tweezers

    PubMed Central

    Bezryadina, Anna S; Preece, Daryl C; Chen, Joseph C; Chen, Zhigang

    2016-01-01

    Bacterial biofilms underlie many persistent infections, posing major hurdles in antibiotic treatment. Here we design and demonstrate ‘tug-of-war’ optical tweezers that can facilitate the assessment of cell–cell adhesion—a key contributing factor to biofilm development, thanks to the combined actions of optical scattering and gradient forces. With a customized optical landscape distinct from that of conventional tweezers, not only can such ‘tug-of-war’ tweezers stably trap and stretch a rod-shaped bacterium in the observing plane, but, more importantly, they can also impose a tunable lateral force that pulls apart cellular clusters without any tethering or mechanical movement. As a proof of principle, we examined a Sinorhizobium meliloti strain that forms robust biofilms and found that the strength of intercellular adhesion depends on the growth medium. This technique may herald new photonic tools for optical manipulation and biofilm study, as well as other biological applications. PMID:27818838

  17. Thermal gradient induced tweezers for the manipulation of particles and cells.

    PubMed

    Chen, Jiajie; Cong, Hengji; Loo, Fong-Chuen; Kang, Zhiwen; Tang, Minghui; Zhang, Haixi; Wu, Shu-Yuen; Kong, Siu-Kai; Ho, Ho-Pui

    2016-11-17

    Optical tweezers are a well-established tool for manipulating small objects. However, their integration with microfluidic devices often requires an objective lens. More importantly, trapping of non-transparent or optically sensitive targets is particularly challenging for optical tweezers. Here, for the first time, we present a photon-free trapping technique based on electro-thermally induced forces. We demonstrate that thermal-gradient-induced thermophoresis and thermal convection can lead to trapping of polystyrene spheres and live cells. While the subject of thermophoresis, particularly in the micro- and nano-scale, still remains to be fully explored, our experimental results have provided a reasonable explanation for the trapping effect. The so-called thermal tweezers, which can be readily fabricated by femtosecond laser writing, operate with low input power density and are highly versatile in terms of device configuration, thus rendering high potential for integration with microfluidic devices as well as lab-on-a-chip systems.

  18. Temperature-dependent conformations of a membrane supported zinc porphyrin tweezer by 2D fluorescence spectroscopy.

    PubMed

    Widom, Julia R; Lee, Wonbae; Perdomo-Ortiz, Alejandro; Rappoport, Dmitrij; Molinski, Tadeusz F; Aspuru-Guzik, Alán; Marcus, Andrew H

    2013-07-25

    We studied the equilibrium conformations of a zinc porphyrin tweezer composed of two carboxylphenyl-functionalized zinc tetraphenyl porphyrin subunits connected by a 1,4-butyndiol spacer, which was suspended inside the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) liposomes. By combining phase-modulation two-dimensional fluorescence spectroscopy (2D FS) with linear absorbance and fluorimetry, we determined that the zinc porphyrin tweezer adopts a mixture of folded and extended conformations in the membrane. By fitting an exciton-coupling model to a series of data sets recorded over a range of temperatures (17-85 °C) and at different laser center wavelengths, we determined that the folded form of the tweezer is stabilized by a favorable change in the entropy of the local membrane environment. Our results provide insights toward understanding the balance of thermodynamic factors that govern molecular assembly in membranes.

  19. Growth in solution of hooked Ni-Fe fibers by oriented rotation and attachment approaches

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Liu, Fang; Zhang, Wei-ze

    2016-04-01

    Inspired by the curved branches of fractal trees, hooked Ni-Fe fibers were grown in situ in Ni-Fe composite coatings on a spheroidal graphite cast iron substrate. These hooked Ni-Fe fibers exhibited inclination angles of about 39°, which was in accordance with the theoretical prediction of 37°. Ni-Fe nanostructures self-assembled to form dendrites and evolved into hooked fibers by an oriented attachment reaction. The orientation rotation of Ni-Fe nanostructures played an important role in the growth of curved hooked Ni-Fe fibers. During sliding wear tests, the volume loss of the spheroidal graphite cast iron substrate was 2.2 times as large as that of the Ni-Fe coating reinforced by hooked fibers. The good load-transferring ability of hooked Ni-Fe fibers led to an improvement in their wear properties during wear tests.

  20. RBCs under optical tweezers as cellular motors and rockers: microfluidic applications

    NASA Astrophysics Data System (ADS)

    Mohanty, Samarendra; Mohanty, Khyati; Gupta, Pradeep

    2006-08-01

    Recently, we have reported self-rotation of normal red blood cells (RBC), suspended in hypertonic buffer, and trapped in unpolarized laser tweezers. Here, we report use of such an optically driven RBC-motor for microfluidic applications such as pumping/centrifugation of fluids. Since the speed of rotation of the RBC-motor was found to vary with the power of the trapping beam, the flow rate could be controlled by controlling the laser power. In polarized optical tweezers, preferential alignment of trapped RBC was observed. The aligned RBC (simulating a disk) in isotonic buffer, could be rotated in a controlled manner for use as a microfluidic valve by rotation of the plane of polarization of the trapping beam. The thickness of the discotic RBC could be changed by changing the osmolarity of the solution and thus the alignment torque on the RBC due to the polarization of the trapping beam could be varied. Further, in polarized tweezers, the RBCs in hypertonic buffer showed rocking motion while being in rotation. Here, the RBC rotated over a finite angular range, stopped for some time at a particular angle, and then started rotating till it was back to the aligned position and this cycle was found repetitive. This can be attributed to the fact that though the RBCs were found to experience an alignment torque to align with plane of polarization of the tweezers due to its form birefringence, it was smaller in magnitude as compared to the rotational torque due to its structural asymmetry in hypertonic solution. Changes in the laser power caused a transition from/to rocking to/from motor behavior of the RBC in a linearly polarized tweezers. By changing the direction of polarization caused by rotation of an external half wave plate, the stopping angle of rocking could be changed. Further, RBCs suspended in intermediate hypertonic buffer and trapped with polarized tweezers showed fluttering about the vertical plane.

  1. Pulse laser assist optical tweezers (PLAT) with long-duration pulse laser

    NASA Astrophysics Data System (ADS)

    Maeda, Saki; Sugiura, Tadao; Minato, Kotaro

    2011-07-01

    Optical tweezers is a technique to trap and to manipulate micron sized objects under a microscope by radiation pressure force exerted by a laser beam. Optical tweezers has been utilized for single-molecular measurements of force exerted by molecular interactions and for cell palpation. To extend applications of optical tweezers we have developed a novel optical tweezers system combined with a pulse laser. We utilize a pulse laser (Q-switched Nd: YAG laser, wavelength of 1064 nm) to assist manipulations by conventional optical tweezers with a continuous wave (CW) laser. The pulse laser beam is introduced into the same optics for conventional optical tweezers. In principle, instantaneous radiation force is proportional to instantaneous power of laser beam. As a result, pulse laser beam generates strong instantaneous force on an object to be manipulated. If the radiation force becomes strong enough to get over an obstacle structure and/or to be released from adhesion, the object will be free from these difficulties. We investigate the effect of pulse laser assistance with changing pulse duration of the laser. We report optimum pulse duration of 100 ns to 200 ns deduced from motion analysis of a particle in a beam spot. Our goal is to realize in-vivo manipulation and operation of a cell. For this purpose we need to reduce light energy of pulse laser beam and to avoid laser induced breakdown caused by strong light field. So we have developed a pulse laser with 160-ns pulse duration and have confirmed that availability on manipulation of living cells.

  2. Two-particle quantum interference in tunnel-coupled optical tweezers.

    PubMed

    Kaufman, A M; Lester, B J; Reynolds, C M; Wall, M L; Foss-Feig, M; Hazzard, K R A; Rey, A M; Regal, C A

    2014-07-18

    The quantum statistics of atoms is typically observed in the behavior of an ensemble via macroscopic observables. However, quantum statistics modifies the behavior of even two particles. Here, we demonstrate near-complete control over all the internal and external degrees of freedom of two laser-cooled (87)Rb atoms trapped in two optical tweezers. This controllability allows us to observe signatures of indistinguishability via two-particle interference. Our work establishes laser-cooled atoms in optical tweezers as a promising route to bottom-up engineering of scalable, low-entropy quantum systems.

  3. Near-field enhanced optical tweezers utilizing femtosecond-laser nanostructured substrates

    SciTech Connect

    Kotsifaki, D. G. Kandyla, M.; Lagoudakis, P. G.

    2015-11-23

    We present experimental evidence of plasmonic-enhanced optical tweezers, of polystyrene beads in deionized water in the vicinity of metal-coated nanostructures. The optical tweezers operate with a continuous wave near-infrared laser. We employ a Cu/Au bilayer that significantly improves dissipation of heat generated by the trapping laser beam and avoid de-trapping from heat convection currents. We investigate the improvement of the optical trapping force and the effective trapping quality factor, and observe an exponential distance dependence of the trapping force from the nanostructures, indicative of evanescent plasmonic enhancement.

  4. Shape deformations of giant unilamellar vesicles with a laser tweezer array

    NASA Astrophysics Data System (ADS)

    Losert, Wolfgang; Poole, Cory; Bradford, Peter; English, Doug

    2004-10-01

    Vesicles are phospholipid bilayers that form a surface enclosing a volume of water or solution. They are of importance as model systems to study cells, as well as having practical applications such as containers for performing nanochemistry and facilitating drug delivery. Their properties have been studied for decades. Using a holographic laser tweezer array (LTA), which converts a single laser beam into many laser tweezer points, we stretch the vesicles in controlled ways from several points at once, measuring each force applied. Here, we present data on shape deformations of simple, spherical vesicles and on membrane fracture.

  5. Manipulating multiparticles simultaneously with tapered-tip single fiber optical tweezers

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Wu, Zhongfu; Liu, Zhihai; Yang, Jun; Yuan, Libo

    2008-12-01

    We present a single-core tapered-tip single fiber optical tweezers, which can trap multi-particle simultaneously. In order to test and verify its new function, finite difference time domain (FDTD) method is used to calculate and simulate. The relationship between the trapping force and the particle-parameters, such as the size, refractive index and others of particle are studied. By experimental validation, the tapered-tip single optic fiber tweezers can trap Particle 2nd after the Particle 1st trapped firmly, but can not trap Particle 3rd, which just verifies the theoretical simulation results to be right.

  6. Ethylene Is Not Responsible for Phytochrome-Mediated Apical Hook Exaggeration in Tomato

    PubMed Central

    Takahashi-Asami, Miki; Shichijo, Chizuko; Tsurumi, Seiji; Hashimoto, Tohru

    2016-01-01

    The apical hook of tomato seedlings is exaggerated by phytochrome actions, while in other species such as bean, pea and Arabidopsis, the hook is exaggerated by ethylene and opens by phytochrome actions. The present study was aimed to clarify mainly whether ethylene is responsible for the phytochrome-mediated hook exaggeration of tomato seedlings. Dark-grown 5-day-old seedlings were subjected to various ways of ethylene application in the dark as well as under the actions of red (R) or far-red light (FR). The ethylene emitted by seedlings was also quantified relative to hook exaggeration. The results show: Ambient ethylene, up-to about 1.0 μL L-1, suppressed (opened) the hooks formed in the dark as well as the ones exaggerated by R or FR, while at 3.0–10 μL L-1 it enhanced (closed) the hook only slightly as compared with the most-suppressed level at about 1.0 μL L-1. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene biosynthesis, did not enhance the hook, only mimicking the suppressive effects of ambient ethylene. The biosynthesis inhibitor, CoCl2 or aminoethoxyvinylglycine, enhanced hook curvature, and the enhancement was canceled by supplement of ethylene below 1.0 μL L-1. Auxin transport inhibitor, N-1-naphthylphthalamic acid, by contrast, suppressed curvature markedly without altering ethylene emission. The effects of the above-stated treatments did not differentiate qualitatively among the R-, FR-irradiated seedlings and dark control so as to explain phytochrome-mediated hook exaggeration. In addition, ethylene emission by seedlings was affected neither by R nor FR at such fluences as to cause hook exaggeration. In conclusion, (1) ethylene suppresses not only the light-exaggerated hook, but also the dark-formed one; (2) ethylene emission is not affected by R or FR, and also not correlated with the hook exaggerations; thus ethylene is not responsible for the hook exaggeration in tomato; and (3) auxin is

  7. Characterisation of coated aerosols using optical tweezers and neutron reflectometry

    NASA Astrophysics Data System (ADS)

    Jones, S. H.; Ward, A.; King, M. D.

    2013-12-01

    Thin organic films are believed to form naturally on the surface of aerosols [1,2] and influence aerosol properties. Cloud condensation nuclei formation and chemical reactions such as aerosol oxidation are effected by the presence of thin films [3]. There is a requirement to characterise the physical properties of both the core aerosol and its organic film in order to fully understand the contribution of coated aerosols to the indirect effect. Two complementary techniques have been used to study the oxidation of thin organic films on the surface of aerosols; laser optical tweezers and neutron reflectometry. Micron sized polystyrene beads coated in oleic acid have been trapped in air using two counter propagating laser beams. Polystyrene beads are used as a proxy for solid aerosol. The trapped aerosol is illuminated with a white LED over a broadband wavelength range and the scattered light collected to produce a Mie spectrum [4]. Analysis of the Mie spectrum results in determination of the core polystyrene bead radius, the oleic acid film thickness and refractive index dispersion of the core and shell [5]. A flow of ozone gas can then be introduced into the aerosol environment to oxidise the thin film of oleic acid and the reaction followed by monitoring the changes in the Mie spectrum. The results demonstrate complete removal of the oleic acid film. We conclude that the use of a counter propagating optical trap combined with white light Mie spectroscopy can be used to study a range of organic films on different types of aerosols and their oxidation reactions. Neutron reflectometry has been used as a complementary technique to study the oxidation of monolayer films at the air-water interface in order to gain information on reaction kinetics. The oxidation of an oleic acid film at the air-water interface by the common tropospheric oxidant ozone has been studied using a Langmuir trough. Results indicate complete removal of the oleic acid film with ozone in agreement

  8. Investigating intermolecular forces associated with thrombus initiation using optical tweezers

    NASA Astrophysics Data System (ADS)

    Arya, Maneesh; Lopez, Jose A.; Romo, Gabriel M.; Dong, Jing-Fei; McIntire, Larry V.; Moake, Joel L.; Anvari, Bahman

    2002-05-01

    Thrombus formation occurs when a platelet membrane receptor, glycoprotein (GP) Ib-IX-V complex, binds to its ligand, von Willebrand factor (vWf), in the subendothelium or plasma. To determine which GP Ib-IX-V amino acid sequences are critical for bond formation, we have used optical tweezers to measure forces involved in the binding of vWf to GP Ib-IX-V variants. Inasmuch as GP Ib(alpha) subunit is the primary component in human GP Ib-IX-V complex that binds to vWf, and that canine GP Ib(alpha) , on the other hand, does not bind to human vWf, we progressively replaced human GP Ib(alpha) amino acid sequences with canine GP Ib(alpha) sequences to determine the sequences essential for vWf/GP Ib(alpha) binding. After measuring the adhesive forces between optically trapped, vWf-coated beads and GP Ib(alpha) variants expressed on mammalian cells, we determined that leucine- rich repeat 2 of GP Ib(alpha) was necessary for vWf/GP Ib-IX- V bond formation. We also found that deletion of the N- terminal flanking sequence and leucine-rich repeat 1 reduced adhesion strength to vWf but did not abolish binding. While divalent cations are known to influence binding of vWf, addition of 1mM CaCl2 had no effect on measured vWf/GP Ib(alpha) bond strengths.

  9. Dynamic properties of bacterial pili measured by optical tweezers

    NASA Astrophysics Data System (ADS)

    Fallman, Erik G.; Andersson, Magnus J.; Schedin, Staffan S.; Jass, Jana; Uhlin, Bernt Eric; Axner, Ove

    2004-10-01

    The ability of uropathogenic Escherichia coli (UPEC) to cause urinary tract infections is dependent on their ability to colonize the uroepithelium. Infecting bacteria ascend the urethra to the bladder and then kidneys by attaching to the uroepithelial cells via the differential expression of adhesins. P pili are associated with pyelonephritis, the more severe infection of the kidneys. In order to find means to treat pyelonephritis, it is therefore of interest to investigate the properties P pili. The mechanical behavior of individual P pili of uropathogenic Escherichia coli has recently been investigated using optical tweezers. P pili, whose main part constitutes the PapA rod, composed of ~1000 PapA subunits in a helical arrangement, are distributed over the bacterial surface and mediate adhesion to host cells. We have earlier studied P pili regarding its stretching/elongation properties where we have found and characterized three different elongation regions, of which one constitute an unfolding of the quaternary (helical) structure of the PapA rod. It was shown that this unfolding takes place at an elongation independent force of 27 +/- 2 pN. We have also recently performed studies on its folding properties and shown that the unfolding/folding of the PapA rod is completely reversible. Here we present a study of the dynamical properties of the PapA rod. We show, among other things, that the unfolding force increases and that the folding force decreases with the speed of unfolding and folding respectively. Moreover, the PapA rod can be folded-unfolded a significant number of times without loosing its characteristics, a phenomenon that is believed to be important for the bacterium to keep close contact to the host tissue and consequently helps the bacterium to colonize the host tissue.

  10. Mechanical properties of stored red blood cells using optical tweezers

    NASA Astrophysics Data System (ADS)

    Fontes, Adriana; Alexandre de Thomaz, Andre; de Ysasa Pozzo, Liliana; de Lourdes Barjas-Castro, Maria; Brandao, Marcelo M.; Saad, Sara T. O.; Barbosa, Luiz Carlos; Cesar, Carlos Lenz

    2005-08-01

    We have developed a method for measuring the red blood cell (RBC) membrane overall elasticity μ by measuring the deformation of the cells when dragged at a constant velocity through a plasma fluid by an optical tweezers. The deformability of erythrocytes is a critical determinant of blood flow in the microcirculation. We tested our method and hydrodynamic models, which included the presence of two walls, by measuring the RBC deformation as a function of drag velocity and of the distance to the walls. The capability and sensitivity of this method can be evaluated by its application to a variety of studies, such as, the measurement of RBC elasticity of sickle cell anemia patients comparing homozygous (HbSS), including patients taking hydroxyrea (HU) and heterozygous (HbAS) with normal donors and the RBC elasticity measurement of gamma irradiated stored blood for transfusion to immunosupressed patients as a function of time and dose. These studies show that the technique has the sensitivity to discriminate heterozygous and homozygous sickle cell anemia patients from normal donors and even follow the course of HU treatment of Homozygous patients. The gamma irradiation studies show that there is no significant change in RBC elasticity over time for up to 14 days of storage, regardless of whether the unit was irradiated or not, but there was a huge change in the measured elasticity for the RBC units stored for more than 21 days after irradiation. These finds are important for the assessment of stored irradiated RBC viability for transfusion purposes because the present protocol consider 28 storage days after irradiation as the limit for the RBC usage.

  11. Substrate-dependent cell elasticity measured by optical tweezers indentation

    NASA Astrophysics Data System (ADS)

    Yousafzai, Muhammad S.; Ndoye, Fatou; Coceano, Giovanna; Niemela, Joseph; Bonin, Serena; Scoles, Giacinto; Cojoc, Dan

    2016-01-01

    In the last decade, cell elasticity has been widely investigated as a potential label free indicator for cellular alteration in different diseases, cancer included. Cell elasticity can be locally measured by pulling membrane tethers, stretching or indenting the cell using optical tweezers. In this paper, we propose a simple approach to perform cell indentation at pN forces by axially moving the cell against a trapped microbead. The elastic modulus is calculated using the Hertz-model. Besides the axial component, the setup also allows us to examine the lateral cell-bead interaction. This technique has been applied to measure the local elasticity of HBL-100 cells, an immortalized human cell line, originally derived from the milk of a woman with no evidence of breast cancer lesions. In addition, we have studied the influence of substrate stiffness on cell elasticity by performing experiments on cells cultured on two substrates, bare and collagen-coated, having different stiffness. The mean value of the cell elastic modulus measured during indentation was 26±9 Pa for the bare substrate, while for the collagen-coated substrate it diminished to 19±7 Pa. The same trend was obtained for the elastic modulus measured during the retraction of the cell: 23±10 Pa and 13±7 Pa, respectively. These results show the cells adapt their stiffness to that of the substrate and demonstrate the potential of this setup for low-force probing of modifications to cell mechanics induced by the surrounding environment (e.g. extracellular matrix or other cells).

  12. Robert Hooke: early respiratory physiologist, polymath, and mechanical genius.

    PubMed

    West, John B

    2014-07-01

    Robert Hooke (1635-1703) was a polymath who made important contributions to respiratory physiology and many other scientific areas. With Robert Boyle, he constructed the first air pump that allowed measurements on small animals at a reduced atmospheric pressure, and this started the discipline of high-altitude physiology. He also built the first human low-pressure chamber and described his experiences when the pressure was reduced to the equivalent of an altitude of ∼2,400 m. Using artificial ventilation in an animal preparation, he demonstrated that movement of the lung was not essential for life. His book Micrographia describing early studies with a microscope remains a classic. He produced an exquisite drawing of the head of a fly, showing the elaborate compound eye. There is also a detailed drawing of a flea, and Hooke noted how the long, many-jointed legs enable the insect to jump so high. For 40 years, he was the curator of experiments for the newly founded Royal Society in London and contributed greatly to its intellectual ferment. His mechanical inventions covered an enormous range, including the watch spring, the wheel barometer, and the universal joint. Following the Great Fire of London in 1666, he designed many of the new buildings in conjunction with Christopher Wren. Unfortunately, Hooke had an abrasive personality, which was partly responsible for a lack of recognition of his work for many years. However, during the last 25 years, there has been renewed interest, and he is now recognized as a brilliant scientist and innovator.

  13. An experimental 'Life' for an experimental life: Richard Waller's biography of Robert Hooke (1705).

    PubMed

    Moxham, Noah

    2016-03-01

    Richard Waller's 'Life of Dr Robert Hooke', prefixed to his edition of Hooke's Posthumous Works (1705), is an important source for the life of one of the most eminent members of the early Royal Society. It also has the distinction of being one of the earliest biographies of a man of science to be published in English. I argue that it is in fact the first biography to embrace the subject's natural-philosophical work as the centre of his life, and I investigate Waller's reasons for adopting this strategy and his struggle with the problem of how to represent an early experimental philosopher in print. I suggest that Waller eschews the 'Christian philosopher' tradition of contemporary biography - partly because of the unusually diverse and fragmentary nature of Hooke's intellectual output - and draws instead upon the structure of the Royal Society's archive as a means of organizing and understanding Hooke's life. The most quoted phrase from Waller's biography is that Hooke became 'to a crime close and reserved' in later life; this essay argues that Waller's biographical sketch was fashioned in order to undo the effects of that reserve. In modelling his approach very closely on the structure of the society's records he was principally concerned with making Hooke's work and biography accessible, intelligible and useful to the fellowship in a context familiar to them, a context which had provided the institutional framework for most of Hooke's adult life. I argue that Waller's 'Life' was also intended to make the largest claims for Hooke's intellectual standing that the author dared in the context of the enmity between Hooke and Isaac Newton once the latter became president of the Royal Society. However, I also adduce fresh manuscript evidence that Waller actually compiled, but did not publish, a defence of Hooke's claim to have discovered the inverse square law of gravity, allowing us to glimpse a much more assertive biography of Hooke than the published version.

  14. The influence of hook type, angler experience, and fish size on injury rates and the duration of capture in an Alaskan catch-and-release rainbow trout fishery

    USGS Publications Warehouse

    Meka, Julie M.

    2004-01-01

    Owing to concerns about the high incidence of past hooking injuries in Alagnak River rainbow trout Oncorhynchus mykiss, fish were captured with spin- and fly-fishing gear with barbed and barbless circle and "J" hooks to determine gear types contributing to injury. Landing and hook removal times were measured for a portion of fish captured, and the anatomical hooking location, hooking scar locations, bleeding intensity, angler experience, and fish size were recorded for all captured fish. Approximately 62% of fish captured experienced at least one new hooking injury, and 29% of fish had at least one past hooking injury. Small fish sustained higher new injury and bleeding rates, but large fish had higher past injury rates. Injury rates were higher for barbed J hooks, barbed J hooks took longer to remove, and fish caught by spin-fishing were injured more frequently than fish caught by fly-fishing. Fewer fly-fishing-caught fish were injured using circle hooks, and circle hooks tended to hook fish in only one location, generally in the jaw. Barbed J hooks were more efficient at landing fish, and J hooks were more efficient at landing fish than circle hooks. Novice anglers injured proportionally more fish than experienced anglers, primarily during hook removal. Landing time was positively correlated with fish size, and experienced anglers took longer to land fish than novices because they captured larger fish. These results suggest that a reduction in hooking injuries may be achieved by using circle hooks as an alternative to J hooks and barbless J hooks to reduce injury and handling time, yet catch efficiency for both methods would be reduced. Although fish captured with barbless J hooks and circle hooks had fewer injuries, it is important to note that each hook type also caused significant injury, and angler education is recommended to promote proper hook removal techniques.

  15. Neurotropic components from star anise (Illicium verum Hook. fil.)

    PubMed

    Nakamura, T; Okuyama, E; Yamazaki, M

    1996-10-01

    Three new neurotropic sesquiterpenoids, veranisatins A, B and C, were isolated from star anise (Illicium verum Hook. fil., Illiciaceae). Veranisatins showed convulsion and lethal toxicity in mice at a dose of 3 mg/kg (p.o.), and at lower doses they caused hypothermia. Veranisatin A and the related compound, anisatin, were tested for the other pharmacological activities such as locomotor activity and analgesic effect. Both compounds decreased the locomotion enhanced by methamphetamine at oral doses of 0.1 and 0.03 mg/kg, respectively, and demonstrated the analgesia on acetic acid-induced writhing and tail pressure pain at almost similar doses.

  16. Red blood cell micromanipulation with elliptical laser beam profile optical tweezers in different osmolarity conditions

    NASA Astrophysics Data System (ADS)

    Spyratou, E.; Makropoulou, M.; Serafetinides, A. A.

    2011-07-01

    In this work optical tweezers with elliptical beam profiles have been developed in order to examine the effect of optical force on fresh red blood cells (RBC) in isotonic, hypertonic and hypotonic buffer solutions. Considering that the optical force depends essentially on the cell surface and the cytoplasmic refractive index, it is obvious that biochemical modifications associated with different states of the cell will influence its behaviour in the optical trap. Line optical tweezers were used to manipulate simultaneously more than one red blood cell. After we have been manipulated a RBC with an elliptical laser beam profile in an isotonic or hypertonic buffer, we noticed that it rotates by itself when gets trapped by optical tweezers and undergoes folding. Further shape deformations can be observed attributed to the competition between alignment and rotational torque which are transferred by laser light to the cell. In hypotonic buffer RBCs become spherical and do not rotate or fold since the resultant force due to rays emerging from diametrically opposite points of the cell leads to zero torque. Manipulation of fresh red blood cells in isotonic solution by line optical tweezers leads to folding and elongation of trapped RBCs. Membrane elasticity properties such as bending modulus can be estimated by measuring RBC's folding time in function with laser power.

  17. Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

    PubMed Central

    van Oene, Maarten M.; Dickinson, Laura E.; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H.

    2017-01-01

    The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor’s response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor’s performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level. PMID:28266562

  18. Listening to proteins and viruses with nanoaperture optical tweezers (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Gordon, Reuven

    2015-08-01

    This talk will present a nanoaperture tweezer approach to measure the acoustic spectra of viruses and single proteins. The approach, termed extraordinary optical Raman (EAR), shows promise for uncovering the structure and mechanical properties of nanoparticles as well as the effects of their interactions.

  19. High Spatiotemporal-Resolution Magnetic Tweezers: Calibration and Applications for DNA Dynamics

    PubMed Central

    Dulin, David; Cui, Tao Ju; Cnossen, Jelmer; Docter, Margreet W.; Lipfert, Jan; Dekker, Nynke H.

    2015-01-01

    The observation of biological processes at the molecular scale in real time requires high spatial and temporal resolution. Magnetic tweezers are straightforward to implement, free of radiation or photodamage, and provide ample multiplexing capability, but their spatiotemporal resolution has lagged behind that of other single-molecule manipulation techniques, notably optical tweezers and AFM. Here, we present, to our knowledge, a new high-resolution magnetic tweezers apparatus. We systematically characterize the achievable spatiotemporal resolution for both incoherent and coherent light sources, different types and sizes of beads, and different types and lengths of tethered molecules. Using a bright coherent laser source for illumination and tracking at 6 kHz, we resolve 3 Å steps with a 1 s period for surface-melted beads and 5 Å steps with a 0.5 s period for double-stranded-dsDNA-tethered beads, in good agreement with a model of stochastic bead motion in the magnetic tweezers. We demonstrate how this instrument can be used to monitor the opening and closing of a DNA hairpin on millisecond timescales in real time, together with attendant changes in the hairpin dynamics upon the addition of deoxythymidine triphosphate. Our approach opens up the possibility of observing biological events at submillisecond timescales with subnanometer resolution using camera-based detection. PMID:26588570

  20. Research Advances: Nanoscale Molecular Tweezers; Cinnamon as Pesticide?; Recently Identified Dietary Sources of Antioxidants

    NASA Astrophysics Data System (ADS)

    King, Angela G.

    2004-12-01

    This Report from Other Journals surveys articles of interest to chemists that have been recently published in other science journals. Topics surveyed include reports that receptors have been designed to act as molecular tweezers; cinnamon has potential in the fight against mosquitoes; and high levels of antioxidants are found in some surprising foods. See Featured Molecules .

  1. Stress response in Caenorhabditis elegans caused by optical tweezers: wavelength, power, and time dependence.

    PubMed Central

    Leitz, Guenther; Fällman, Erik; Tuck, Simon; Axner, Ove

    2002-01-01

    Optical tweezers have emerged as a powerful technique for micromanipulation of living cells. Although the technique often has been claimed to be nonintrusive, evidence has appeared that this is not always the case. This work presents evidence that near-infrared continuous-wave laser light from optical tweezers can produce stress in Caenorhabditis elegans. A transgenic strain of C. elegans, carrying an integrated heat-shock-responsive reporter gene, has been exposed to laser light under a variety of illumination conditions. It was found that gene expression was most often induced by light of 760 nm, and least by 810 nm. The stress response increased with laser power and irradiation time. At 810 nm, significant gene expression could be observed at 360 mW of illumination, which is more than one order of magnitude above that normally used in optical tweezers. In the 700-760-nm range, the results show that the stress response is caused by photochemical processes, whereas at 810 nm, it mainly has a photothermal origin. These results give further evidence that the 700-760-nm wavelength region is unsuitable for optical tweezers and suggest that work at 810 nm at normal laser powers does not cause stress at the cellular level. PMID:11916877

  2. Inversion of product selectivity in an enzyme-inspired metallosupramolecular tweezer catalyzed epoxidation reaction†

    PubMed Central

    Ulmann, Pirmin A.; Braunschweig, Adam B.; Lee, One-Sun; Wiester, Michael J.

    2014-01-01

    This study describes a heteroligated, hemilabile PtII–P,S tweezer coordination complex that combines a chiral Jacobsen–Katsuki MnIII-salen epoxidation catalyst with an amidopyridine receptor, which leads to an inversion of the major epoxide product compared to catalysts without a recognition group. PMID:20448966

  3. Multifunctional single beam acoustic tweezer for non-invasive cell/organism manipulation and tissue imaging

    PubMed Central

    Lam, Kwok Ho; Li, Ying; Li, Yang; Lim, Hae Gyun; Zhou, Qifa; Shung, Koping Kirk

    2016-01-01

    Non-contact precise manipulation of single microparticles, cells, and organisms has attracted considerable interest in biophysics and biomedical engineering. Similar to optical tweezers, acoustic tweezers have been proposed to be capable of manipulating microparticles and even cells. Although there have been concerted efforts to develop tools for non-contact manipulation, no alternative to complex, unifunctional tweezer has yet been found. Here we report a simple, low-cost, multifunctional single beam acoustic tweezer (SBAT) that is capable of manipulating an individual micrometer scale non-spherical cell at Rayleigh regime and even a single millimeter scale organism at Mie regime, and imaging tissue as well. We experimentally demonstrate that the SBAT with an ultralow f-number (f# = focal length/aperture size) could manipulate an individual red blood cell and a single 1.6 mm-diameter fertilized Zebrafish egg, respectively. Besides, in vitro rat aorta images were collected successfully at dynamic foci in which the lumen and the outer surface of the aorta could be clearly seen. With the ultralow f-number, the SBAT offers the combination of large acoustic radiation force and narrow beam width, leading to strong trapping and high-resolution imaging capabilities. These attributes enable the feasibility of using a single acoustic device to perform non-invasive multi-functions simultaneously for biomedical and biophysical applications. PMID:27874052

  4. Multifunctional single beam acoustic tweezer for non-invasive cell/organism manipulation and tissue imaging

    NASA Astrophysics Data System (ADS)

    Lam, Kwok Ho; Li, Ying; Li, Yang; Lim, Hae Gyun; Zhou, Qifa; Shung, Koping Kirk

    2016-11-01

    Non-contact precise manipulation of single microparticles, cells, and organisms has attracted considerable interest in biophysics and biomedical engineering. Similar to optical tweezers, acoustic tweezers have been proposed to be capable of manipulating microparticles and even cells. Although there have been concerted efforts to develop tools for non-contact manipulation, no alternative to complex, unifunctional tweezer has yet been found. Here we report a simple, low-cost, multifunctional single beam acoustic tweezer (SBAT) that is capable of manipulating an individual micrometer scale non-spherical cell at Rayleigh regime and even a single millimeter scale organism at Mie regime, and imaging tissue as well. We experimentally demonstrate that the SBAT with an ultralow f-number (f# = focal length/aperture size) could manipulate an individual red blood cell and a single 1.6 mm-diameter fertilized Zebrafish egg, respectively. Besides, in vitro rat aorta images were collected successfully at dynamic foci in which the lumen and the outer surface of the aorta could be clearly seen. With the ultralow f-number, the SBAT offers the combination of large acoustic radiation force and narrow beam width, leading to strong trapping and high-resolution imaging capabilities. These attributes enable the feasibility of using a single acoustic device to perform non-invasive multi-functions simultaneously for biomedical and biophysical applications.

  5. Force Spectroscopy with Dual-Trap Optical Tweezers: Molecular Stiffness Measurements and Coupled Fluctuations Analysis

    PubMed Central

    Ribezzi-Crivellari, M.; Ritort, F.

    2012-01-01

    Dual-trap optical tweezers are often used in high-resolution measurements in single-molecule biophysics. Such measurements can be hindered by the presence of extraneous noise sources, the most prominent of which is the coupling of fluctuations along different spatial directions, which may affect any optical tweezers setup. In this article, we analyze, both from the theoretical and the experimental points of view, the most common source for these couplings in dual-trap optical-tweezers setups: the misalignment of traps and tether. We give criteria to distinguish different kinds of misalignment, to estimate their quantitative relevance and to include them in the data analysis. The experimental data is obtained in a, to our knowledge, novel dual-trap optical-tweezers setup that directly measures forces. In the case in which misalignment is negligible, we provide a method to measure the stiffness of traps and tether based on variance analysis. This method can be seen as a calibration technique valid beyond the linear trap region. Our analysis is then employed to measure the persistence length of dsDNA tethers of three different lengths spanning two orders of magnitude. The effective persistence length of such tethers is shown to decrease with the contour length, in accordance with previous studies. PMID:23199920

  6. Adhesion of nanoparticles to polymer brushes studied with the ghost tweezers method.

    PubMed

    Cheng, Jianli; Vishnyakov, Aleksey; Neimark, Alexander V

    2015-01-21

    Mechanisms of interactions between nanoparticles (NPs) and polymer brushes (PBs) are explored using dissipative particle dynamics simulations and an original "ghost tweezers" method that emulates lab experiments performed with optical or magnetic tweezers. The ghost tweezers method is employed to calculate the free energy of adhesion. Ghost tweezers represents a virtual harmonic potential, which tethers NP with a spring to a given anchor point. The average spring force represents the effective force of NP-PB interaction as a function of the NP coordinate. The free energy landscape of NP-PB interactions is calculated as the mechanical work needed to transfer NP from the solvent bulk to a particular distance from the substrate surface. With this technique, we explore the adhesion of bare and ligand-functionalized spherical NPs to polyisoprene natural rubber brush in acetone-benzene binary solvent. We examine two basic mechanisms of NP-PB interactions, NP adhesion at PB exterior and NP immersion into PB, which are governed by interplay between entropic repulsive forces and enthalpic attractive forces caused by polymer adsorption at the NP surface and ligand adsorption at the substrate. The relative free energies of the equilibrium adhesion states and the potential barriers separating these states are calculated at varying grafting density, NP size, and solvent composition.

  7. RBC aggregation dynamics in autologous plasma and serum studied with double-channel optical tweezers

    NASA Astrophysics Data System (ADS)

    Lee, Kisung; Danilina, Anna; Potkin, Anton; Kinnunen, Matti; Priezzhev, Alexander; Meglinski, Igor

    2016-04-01

    Red blood cells aggregating and disaggregating forces were measured in the autologous plasma and serum using the double-channeled optical tweezers. A significant, three-fold decrease of the both forces was observed in the serum compared to the plasma. The results of this study help to better assess the RBC aggregation mechanism.

  8. Development of high frequency focused transducers for single beam acoustic tweezers

    NASA Astrophysics Data System (ADS)

    Hsu, Hsiu-Sheng

    Contactless particle trapping and manipulation have found many potential applications in diverse fields, especially in biological and medical research. Among the various methods, optical tweezers is the most well-known and extensively investigated technique. However, there are some limitations for particle manipulation based on optical tweezers. Due to the conceptual similarity with the optical tweezers and recent advances in high frequency ultrasonic transducer, a single beam acoustic tweezer using high frequency (≥ 20 MHz) focused transducer has recently been considered, and its feasibility was theoretically and experimentally investigated. This dissertation mainly describes the development of high frequency focused ultrasonic transducers for single beam acoustic tweezers applications. Three different types of transducers were fabricated. First, a 60 MHz miniature focused transducer (<1 mm) was made using press-focusing technique. The single beam acoustic trapping experiment was performed to manipulate 15 microm polystyrene microspheres using this transducer. In vitro ultrasonic biomicroscopy imaging on the rabbit eye was also obtained with this device. Second approach is to build a 200 MHz self-focused ZnO transducer by sputtering ZnO film on a curved surface of the aluminum backing material. An individual 10 microm microsphere was effectively manipulated in two dimensions by this type of transducer. Another ultrahigh frequency focused transducer based on silicon lens design has also been developed, where a 330 MHz silicon lens transducer was fabricated and evaluated. Microparticle trapping experiment was carried out to demonstrate that silicon lens transducer can manipulate a single microsphere as small as 5 microm. The realization of single beam acoustic tweezers using high frequency focused transducers can offer wide range of applications in biomedical and chemical sciences including intercellular kinetics studies and cell stimulation. Additionally, we

  9. Are College Students Replacing Dating and Romantic Relationships with Hooking Up?

    ERIC Educational Resources Information Center

    Siebenbruner, Jessica

    2013-01-01

    This study assessed female college students' ("N" = 197) participation in dating, romantic relationships, hooking up behaviors, and the intersection of these activities. Hooking up was prevalent among students ("n" = 78; 39.6%), but dating ("n" = 139; 70.6%) and romantic relationship ("n" = 147; 74.6%)…

  10. 33 CFR 165.130 - Sandy Hook Bay, New Jersey-security zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Sandy Hook Bay, New Jersey... Hook Bay, New Jersey—security zone. (a) Naval Ammunition Depot Piers. The navigable waters within the... at Leonardo, New Jersey. (3) Vessels may enter or cross the security zone, except as provided...

  11. When Teachers Aren't Nice: bell hooks and Feminist Pedagogy.

    ERIC Educational Resources Information Center

    Buffington, Nancy

    The recent "feminization" of composition theory and pedagogy has replaced the classroom figure of the authoritative father with an image of a nurturing mother. But as bell hooks and others insist, the classroom is inherently a place of struggle and conflict and the "real world" is even more so. Hooks offers concrete…

  12. 33 CFR 80.170 - Sandy Hook, NJ to Tom's River, NJ.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Sandy Hook, NJ to Tom's River, NJ. 80.170 Section 80.170 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Atlantic Coast § 80.170 Sandy Hook, NJ to Tom's...

  13. Collaborative Lesson Hook Design in Science Teacher Education: Advancing Professional Practice

    ERIC Educational Resources Information Center

    McCauley, Veronica; Davison, Kevin; Byrne, Corinna

    2015-01-01

    This article documents the process of collaboratively developing lesson hook e-resources for science teachers to establish a community of inquiry and to strengthen the pedagogy of science teaching. The authors aim to illustrate how the development and application of strategic hooks can bridge situational interest and personal interest so that…

  14. Building Prior Knowledge and Vocabulary in Science in the Intermediate Grades: Creating Hooks for Learning

    ERIC Educational Resources Information Center

    Rupley, William H.; Slough, Scott

    2010-01-01

    Vocabulary knowledge is a salient factor influencing success both in and out of school. The specialized vocabulary knowledge in science represents the concept-laden hooks on which learning is hung and enables students to build prior knowledge through the expansion of these conceptual hooks. We have identified four levels of learners--struggling…

  15. 33 CFR 165.130 - Sandy Hook Bay, New Jersey-security zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Hook Bay, New Jersey—security zone. (a) Naval Ammunition Depot Piers. The navigable waters within the... at Leonardo, New Jersey. (3) Vessels may enter or cross the security zone, except as provided in... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Sandy Hook Bay, New...

  16. 77 FR 76510 - Prime Hook National Wildlife Refuge, Sussex County, DE; Final Comprehensive Conservation Plan and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-28

    ...-4311-K9-S3] Prime Hook National Wildlife Refuge, Sussex County, DE; Final Comprehensive Conservation... conservation plan (CCP) and environmental impact statement (EIS) for Prime Hook National Wildlife Refuge (NWR... should be consistent with sound principles of fish and wildlife management, conservation, legal...

  17. 77 FR 47435 - Prime Hook National Wildlife Refuge, Sussex County, DE; Draft Comprehensive Conservation Plan and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-08

    ... Fish and Wildlife Service Prime Hook National Wildlife Refuge, Sussex County, DE; Draft Comprehensive Conservation Plan and Environmental Impact Statement AGENCY: Fish and Wildlife Service, Interior. ACTION... conservation plan and draft environmental impact statement (draft CCP/EIS) for Prime Hook National...

  18. Interactions of light and ethylene in hypocotyl hook maintenance in Arabidopsis thaliana seedlings

    NASA Technical Reports Server (NTRS)

    Knee, E. M.; Hangarter, R. P.; Knee, M.

    2000-01-01

    Etiolated seedlings frequently display a hypocotyl or epicotyl hook which opens on exposure to light. Etylene has been shown to be necessary for maintenance of the hook in a number of plants in darkness. We investigated the interaction of ethylene and light in the regulation of hypocotyl hook opening in Arabidopsis thaliana. We found that hooks of Arabidopsis open in response to continuous red, far-red or blue light in the presence of up to 100 microliters l-1 ethylene. Thus a change in sensitivity to ethylene is likely to be responsible for hook opening in Arabidopsis, rather than a decrease in ethylene production in hook tissues. We used photomorphogenic mutants of Arabidopsis to demonstrate the involvement of both blue light and phytochrome photosensory systems in light-induced hook opening in the presence of ethylene. In addition we used ethylene mutants and inhibitors of ethylene action to investigate the role of ethylene in hook maintenance in seedlings grown in light and darkness.

  19. Definition of Metrics to Evaluate Cochlear Array Insertion Forces Performed with Forceps, Insertion Tool, or Motorized Tool in Temporal Bone Specimens

    PubMed Central

    Ferrary, Evelyne; Sterkers, Olivier

    2014-01-01

    Introduction. In order to achieve a minimal trauma to the inner ear structures during array insertion, it would be suitable to control insertion forces. The aim of this work was to compare the insertion forces of an array insertion into anatomical specimens with three different insertion techniques: with forceps, with a commercial tool, and with a motorized tool. Materials and Methods. Temporal bones have been mounted on a 6-axis force sensor to record insertion forces. Each temporal bone has been inserted, with a lateral wall electrode array, in random order, with each of the 3 techniques. Results. Forceps manual and commercial tool insertions generated multiple jerks during whole length insertion related to fits and starts. On the contrary, insertion force with the motorized tool only rose at the end of the insertion. Overall force momentum was 1.16 ± 0.505 N (mean ± SD, n = 10), 1.337 ± 0.408 N (n = 8), and 1.573 ± 0.764 N (n = 8) for manual insertion with forceps and commercial and motorized tools, respectively. Conclusion. Considering force momentum, no difference between the three techniques was observed. Nevertheless, a more predictable force profile could be observed with the motorized tool with a smoother rise of insertion forces. PMID:25126565

  20. Oscillating optical tweezer-based 3-D confocal microrheometer for investigating the intracellular micromechanics and structures

    NASA Astrophysics Data System (ADS)

    Ou-Yang, H. D.; Rickter, E. A.; Pu, C.; Latinovic, O.; Kumar, A.; Mengistu, M.; Lowe-Krentz, L.; Chien, S.

    2005-08-01

    Mechanical properties of living biological cells are important for cells to maintain their shapes, support mechanical stresses and move through tissue matrix. The use of optical tweezers to measure micromechanical properties of cells has recently made significant progresses. This paper presents a new approach, the oscillating optical tweezer cytorheometer (OOTC), which takes advantage of the coherent detection of harmonically modulated particle motions by a lock-in amplifier to increase sensitivity, temporal resolution and simplicity. We demonstrate that OOTC can measure the dynamic mechanical modulus in the frequency range of 0.1-6,000 Hz at a rate as fast as 1 data point per second with submicron spatial resolution. More importantly, OOTC is capable of distinguishing the intrinsic non-random temporal variations from random fluctuations due to Brownian motion; this capability, not achievable by conventional approaches, is particular useful because living systems are highly dynamic and often exhibit non-thermal, rhythmic behavior in a broad time scale from a fraction of a second to hours or days. Although OOTC is effective in measuring the intracellular micromechanical properties, unless we can visualize the cytoskeleton in situ, the mechanical property data would only be as informative as that of "Blind men and the Elephant". To solve this problem, we take two steps, the first, to use of fluorescent imaging to identify the granular structures trapped by optical tweezers, and second, to integrate OOTC with 3-D confocal microscopy so we can take simultaneous, in situ measurements of the micromechanics and intracellular structure in living cells. In this paper, we discuss examples of applying the oscillating tweezer-based cytorheometer for investigating cultured bovine endothelial cells, the identification of caveolae as some of the granular structures in the cell as well as our approach to integrate optical tweezers with a spinning disk confocal microscope.

  1. Fullerene recognition with molecular tweezers made up of efficient buckybowls: a dispersion-corrected DFT study.

    PubMed

    Josa, Daniela; Rodríguez-Otero, Jesús; Cabaleiro-Lago, Enrique M

    2015-05-28

    In 2007, Sygula and co-workers introduced a novel type of molecular tweezers with buckybowl pincers that have attracted the substantial interest of researchers due to their ideal architecture for recognizing fullerenes by concave-convex π∙∙∙π interactions (A. Sygula et al., J. Am. Chem. Soc., 2007, 129, 3842). Although in recent years some modifications have been performed on these original molecular tweezers to improve their ability for catching fullerenes, very few improvements were achieved to date. For that reason, in the present work a series of molecular tweezers have been devised and their supramolecular complexes with C60 studied at the B97-D2/TZVP//SCC-DFTB-D and B97-D2/TZVP levels. Three different strategies have been tested: (1) changing the corannulene pincers to other buckybowls, (2) replacing the tetrabenzocyclooctatetraene tether by a buckybowl, and (3) adding methyl groups on the molecular tweezers. According to the results, all the three approaches are effective, in such a way that a combination of the three strategies results in buckycatchers with complexation energies (with C60) up to 2.6 times larger than that of the original buckycatcher, reaching almost -100 kcal mol(-1). The B97-D2/TZVP//SCC-DFTB-D approach can be a rapid screening tool for testing new molecular tweezers. However, since this approach does not reproduce correctly the deformation energy and this energy represents an important contribution to the total complexation energy of complexes, subsequent higher-level re-optimization is compulsory to achieve reliable results (the full B97-D2/TZVP level is used herein). This re-optimization could be superfluous when quite rigid buckycatchers are studied.

  2. Hooking tomorrow's geoscientists: Authentic field inquiry as a compelling pedagogy

    NASA Astrophysics Data System (ADS)

    Wallstrom, Erica

    2015-04-01

    Engaging high school students in the geosciences without providing them with opportunities to directly explore, understand, and question the natural world is like trying to catch a fish without a hook. How can educators hope to inspire youth to pursue a career in the geosciences when the subject is first introduced to teenagers within the confines of a classroom? Regardless of the content and activities employed by the teacher, the synthetic classroom setting is unable to recreate the organic richness of an authentic outdoor learning environment. A new course offering at Rutland High School in Rutland, Vermont, USA shifts away from the traditional classroom based pedagogy by focusing the learning on exploring the temporal changes occurring in the region's geologic features. Numerous visits to local quarries, outcrops, overlooks, and universities guide the course curriculum. Students use their new understandings and personal observations to complete a culminating independent investigation. This alternate learning model is made possible through collaboration with local universities, businesses, and government agencies. If the geosciences is to remain competitive in the recruitment of exemplary STEM candidates, than the focus of high school earth science programs must be considered. This course offers one alternative to improve engagement and understanding of the geoscience standards. While not the only option, it offers one possibility for hooking students on geosciences.

  3. THE BLUE HOOK POPULATIONS OF MASSIVE GLOBULAR CLUSTERS

    SciTech Connect

    Brown, Thomas M.; Smith, Ed; Sweigart, Allen V.; Lanz, Thierry; Landsman, Wayne B.; Hubeny, Ivan E-mail: edsmith@stsci.ed E-mail: lanz@astro.umd.ed E-mail: hubeny@aegis.as.arizona.ed

    2010-08-01

    We present new Hubble Space Telescope ultraviolet color-magnitude diagrams of five massive Galactic globular clusters: NGC 2419, NGC 6273, NGC 6715, NGC 6388, and NGC 6441. These observations were obtained to investigate the 'blue hook' (BH) phenomenon previously observed in UV images of the globular clusters {omega} Cen and NGC 2808. Blue hook stars are a class of hot (approximately 35,000 K) subluminous horizontal branch stars that occupy a region of the HR diagram that is unexplained by canonical stellar evolution theory. By coupling new stellar evolution models to appropriate non-LTE synthetic spectra, we investigate various theoretical explanations for these stars. Specifically, we compare our photometry to canonical models at standard cluster abundances, canonical models with enhanced helium (consistent with cluster self-enrichment at early times), and flash-mixed models formed via a late helium-core flash on the white dwarf cooling curve. We find that flash-mixed models are required to explain the faint luminosity of the BH stars, although neither the canonical models nor the flash-mixed models can explain the range of color observed in such stars, especially those in the most metal-rich clusters. Aside from the variation in the color range, no clear trends emerge in the morphology of the BH population with respect to metallicity.

  4. Wound healing of true vocal cord squamous epithelium after CO2 laser ablation and cup forceps stripping.

    PubMed

    Durkin, G E; Duncavage, J A; Toohill, R J; Tieu, T M; Caya, J G

    1986-10-01

    A study was conducted on the effect of deepithelization of the true vocal cords; microcup forceps were used, as opposed to CO2 laser ablation. A CO2 laser, coupled to an operating microscope, was used to ablate the surface epithelium of the right true vocal cords in eight canines, while conventional microlaryngeal stripping was performed on the left true cords in the same animals. Photographs were taken immediately after injury and again before the animals were killed. Histologically, the series of true vocal cords ablated by the CO2 laser revealed granulation formation at day 5, whereas those treated with conventional stripping developed granulation at day 3, thus indicating delayed healing. Charred carbonaceous debris of CO2 laser ablation was found to cause a giant cell reaction that persisted after reepithelization. Despite the precise control offered by the laser, many of the laser-injured true vocal cords revealed vocalis muscle edema and muscle destruction. After healing occurred, dense fibrosis was found in the vocal muscle injured during CO2 laser ablation of the overlying squamous epithelium.

  5. Motorized Force-Sensing Micro-Forceps with Tremor Cancelling and Controlled Micro-Vibrations for Easier Membrane Peeling*

    PubMed Central

    Gonenc, Berk; Gehlbach, Peter; Handa, James; Taylor, Russell H.; Iordachita, Iulian

    2014-01-01

    Retinal microsurgery requires the manipulation of extremely delicate tissues by various micron scale maneuvers and the application of very small forces. Among vitreoretinal procedures, membrane peeling is a standard procedure requiring the delamination of a very thin fibrous membrane on the retina surface. This study presents the development and evaluation of an integrated assistive system for membrane peeling. This system combines a force-sensing motorized micro-forceps with an active tremor-canceling handheld micromanipulator, Micron. The proposed system (1) attenuates hand-tremor when accurate positioning is needed, (2) provides auditory force feedback to keep the exerted forces at a safe level, and (3) pulsates the tool tip at high frequency to provide ease in delaminating membranes. Experiments on bandages and raw chicken eggs have revealed that controlled micro-vibrations provide significant ease in delaminating membranes. Applying similar amount of forces, much faster delamination was observed when the frequency of these vibrations were increased (up to 50 Hz). PMID:25544965

  6. Prevalence of ingested fish hooks in freshwater turtles from five rivers in the southeastern United States.

    PubMed

    Steen, David A; Hopkins, Brittney C; Van Dyke, James U; Hopkins, William A

    2014-01-01

    Freshwater turtles may ingest baited fish hooks because many are opportunistic scavengers. Although the ingestion of fish hooks is known to be a source of mortality in multiple vertebrate groups, the prevalence of hook ingestion by freshwater turtles has not been well studied. We trapped turtles from five rivers in the southeastern United States and used radiographs to examine over 600 individuals of four species. Depending on the species, sex, and age class, 0-33% of turtles contained ingested fish hooks. For some species, larger turtles were more likely to contain a fish hook than smaller individuals. Freshwater turtle demography suggests that even small increases in adult mortality may lead to population declines. If our study areas are representative of other aquatic systems that receive fishing pressure, this work likely identifies a potential conflict between a widespread, common recreational activity (i.e., fishing) and an imperiled taxonomic group.

  7. Prevalence of Ingested Fish Hooks in Freshwater Turtles from Five Rivers in the Southeastern United States

    PubMed Central

    Steen, David A.; Hopkins, Brittney C.; Van Dyke, James U.; Hopkins, William A.

    2014-01-01

    Freshwater turtles may ingest baited fish hooks because many are opportunistic scavengers. Although the ingestion of fish hooks is known to be a source of mortality in multiple vertebrate groups, the prevalence of hook ingestion by freshwater turtles has not been well studied. We trapped turtles from five rivers in the southeastern United States and used radiographs to examine over 600 individuals of four species. Depending on the species, sex, and age class, 0–33% of turtles contained ingested fish hooks. For some species, larger turtles were more likely to contain a fish hook than smaller individuals. Freshwater turtle demography suggests that even small increases in adult mortality may lead to population declines. If our study areas are representative of other aquatic systems that receive fishing pressure, this work likely identifies a potential conflict between a widespread, common recreational activity (i.e., fishing) and an imperiled taxonomic group. PMID:24621919

  8. Extracapsular hip fractures: fixation with a twin hook or a lag screw?

    PubMed

    Olsson, O; Ceder, L; Lunsjö, K; Hauggaard, A

    2000-01-01

    The twin hook, which has 2 oppositely directed apical hooks, is an alternative to the lag screw for use with a 'dynamic plate' in the fixation of trochanteric hip fractures. In this prospective study lasting 1 year, 102 consecutive patients with trochanteric hip fractures were treated by 19 surgeons with either a twin hook or a lag screw combined with a conventional sliding hip screw plate or a Medoff sliding plate. Seven intraoperative errors were made with the twin hook but postoperative migration did not differ significantly between the 2 groups. Postoperative fixation failures were equally distributed between the 2 groups. The twin hook provides adequate fixation, which is comparable to that produced by a lag screw.

  9. 77 FR 20571 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod by Catcher Vessels Using Hook...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-05

    ... Economic Zone Off Alaska; Pacific Cod by Catcher Vessels Using Hook-and-Line Gear in the Western Regulatory... directed fishing for Pacific cod by catcher vessels (CVs) using hook-and-line gear in the Western... allowance of the 2012 Pacific cod total allowable catch apportioned to CVs using hook-and-line gear in...

  10. 78 FR 25004 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod by Catcher Vessels Using Hook...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-29

    ... Economic Zone Off Alaska; Pacific Cod by Catcher Vessels Using Hook-and-Line Gear in the Western Regulatory... directed fishing for Pacific cod by catcher vessels (CVs) using hook-and-line gear in the Western... allowance of the 2013 Pacific cod total allowable catch apportioned to CVs using hook-and-line gear in...

  11. 78 FR 23864 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod by Catcher/Processors Using Hook...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-23

    ... Economic Zone Off Alaska; Pacific Cod by Catcher/Processors Using Hook-and-line Gear in the Western... directed fishing for Pacific cod by catcher/processors (C/Ps) using hook-and-line gear in the Western... allowance of the 2013 Pacific cod total allowable catch apportioned to C/Ps using hook-and-line gear in...

  12. 77 FR 11776 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod by Catcher/Processors Using Hook...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-28

    ... Economic Zone Off Alaska; Pacific Cod by Catcher/Processors Using Hook-and-Line Gear in the Central... directed fishing for Pacific cod by catcher/processors (C/Ps) using hook-and-line gear in the Central... allowance of the 2012 Pacific cod total allowable catch apportioned to C/Ps using hook-and-line gear in...

  13. Molecular and Cellular Characterization of an AT-Hook Protein from Leishmania

    PubMed Central

    Kelly, Ben L.; Singh, Gyanendra; Aiyar, Ashok

    2011-01-01

    AT-rich DNA, and the proteins that bind it (AT-hook proteins), modulate chromosome structure and function in most eukaryotes. Unlike other trypanosomatids, the genome of Leishmania species is unusually GC-rich, and the regulation of Leishmania chromosome structure, replication, partitioning is not fully understood. Because AT-hook proteins modulate these functions in other eukaryotes, we examined whether AT-hook proteins are encoded in the Leishmania genome, to test their potential functions. Several Leishmania ORFs predicted to be AT-hook proteins were identified using in silico approaches based on sequences shared between eukaryotic AT-hook proteins. We have used biochemical, molecular and cellular techniques to characterize the L. amazonensis ortholog of the L. major protein LmjF06.0720, a potential AT-hook protein that is highly conserved in Leishmania species. Using a novel fusion between the AT-hook domain encoded by LmjF06.0720 and a herpesviral protein, we have demonstrated that LmjF06.0720 functions as an AT-hook protein in mammalian cells. Further, as observed for mammalian and viral AT-hook proteins, the AT-hook domains of LmjF06.0720 bind specific regions of condensed mammalian metaphase chromosomes, and support the licensed replication of DNA in mammalian cells. LmjF06.0720 is nuclear in Leishmania, and this localization is disrupted upon exposure to drugs that displace AT-hook proteins from AT-rich DNA. Coincidentally, these drugs dramatically alter the cellular physiology of Leishmania promastigotes. Finally, we have devised a novel peptido-mimetic agent derived from the sequence of LmjF06.0720 that blocks the proliferation of Leishmania promastigotes, and lowers amastigote parasitic burden in infected macrophages. Our results indicate that AT-hook proteins are critical for the normal biology of Leishmania. In addition, we have described a simple technique to examine the function of Leishmania chromatin-binding proteins in a eukaryotic context

  14. Complete structure of the bacterial flagellar hook reveals extensive set of stabilizing interactions

    PubMed Central

    Matsunami, Hideyuki; Barker, Clive S.; Yoon, Young-Ho; Wolf, Matthias; Samatey, Fadel A.

    2016-01-01

    The bacterial flagellar hook is a tubular helical structure made by the polymerization of multiple copies of a protein, FlgE. Here we report the structure of the hook from Campylobacter jejuni by cryo-electron microscopy at a resolution of 3.5 Å. On the basis of this structure, we show that the hook is stabilized by intricate inter-molecular interactions between FlgE molecules. Extra domains in FlgE, found only in Campylobacter and in related bacteria, bring more stability and robustness to the hook. Functional experiments suggest that Campylobacter requires an unusually strong hook to swim without its flagella being torn off. This structure reveals details of the quaternary organization of the hook that consists of 11 protofilaments. Previous study of the flagellar filament of Campylobacter by electron microscopy showed its quaternary structure made of seven protofilaments. Therefore, this study puts in evidence the difference between the quaternary structures of a bacterial filament and its hook. PMID:27811912

  15. Absorption of metals in mulloway (Argyrosomus japonicus) after ingesting nickel-plated carbon-steel hooks.

    PubMed

    McGrath, Shane P; Reichelt-Brushett, Amanda J; Butcher, Paul A; Cairns, Stuart C

    2014-08-01

    Previous research has alluded to the potential of metals being absorbed by fish after ingesting fishing hooks, which may have adverse effects on fish health and the organisms that consume them. Subsequently, this study aimed to quantify the potential of mulloway (Argyrosomus japonicus) to absorb metals during the decay of ingested nickel-plated carbon-steel hooks. Twenty-five treatment fish were allowed to ingest nickel-plated carbon-steel hooks during angling and then monitored with 25 controls (untreated fish) for up to 42 days for hook ejection and mortality. Blood, liver and muscle samples were collected from treatment, control and 14 wild-caught individuals to determine the concentrations of chromium, cobalt, copper, iron, manganese and nickel. The results showed that increased oxidation influenced hook ejection, and that hook-ingested fish had significantly elevated concentrations of nickel in their liver and blood, but not muscle. This research has shown that there is an avenue for metal absorption from ingested hooks.

  16. A biomechanical study on fixation stability with twin hook or lag screw in artificial cancellous bone.

    PubMed

    Olsson, O; Tanner, K E; Ceder, L; Ryd, L

    2002-01-01

    The twin hook has been developed as an alternative to the conventional lag screw to be combined with a barrelled side-plate in the treatment of trochanteric hip fractures. With two oppositely directed apical hooks introduced into the subchondral bone of the femoral head, the twin hook provides different stabilising properties to the lag screw. The femoral head purchase of the twin hook and the lag screw were compared in a biomechanical study using artificial cancellous bone, and responses to axial and torsional loading was determined. A distinct yield point in load and torque was noted for the lag screw, representing failure of the laminas supporting the threads. For the twin hook, gradual increase of load and torque occurred during impaction of the bone supporting the hooks. The peak loads and torques were higher for the lag screw, but were similar for both devices after 8 mm deformation. The stiffness was higher for the lag screw, but in counter-clockwise rotation the stiffness for the lag screw was negligible. The twin hook appeared to provide fixation stability comparable to that offered by the lag screw, but with conceivable advantages in terms of a deformation response involving bone impaction and gradually increasing stability.

  17. Fracture of the hook of the hamate: radiographic visualization.

    PubMed Central

    Carroll, R. E.; Lakin, J. F.

    1993-01-01

    The diagnosis of fracture of the hook of the hamate is rarely made at the time of the initial injury. Routine roentgenograms of the hand in the standard three positions do not visualize this structure. The carpal tunnel view (CTV) with hyperextension of the wrist may be too painful to position. A computerized tomography of the wrist in the transverse or axial plane will clearly and painlessly identify the fracture. Placing both hands and wrists in the praying position gives excellent comparison and documents any developmental bone abnormality. Scintigraphy, when positive, must be followed by tomography or a carpal tunnel view. Images Figure 1 Figure 2 Figure 3 Figure 4 A-B Figure 4C PMID:7820740

  18. [Margaret Cavendish vs Robert Hooke: An impossible duel].

    PubMed

    Aït-Touati, Frédérique

    2016-12-01

    In 1665, Robert Hooke published his major work in microscopy, Micrographia, a defense of experimental philosophy. The following year, Margaret Cavendish, Duchess of Newcastle, published at her own expense a treatise and a novel that undermined the basis of this new science. The dispute broke out at the initiative of the Duchess, in the context of a vast controversy about the legitimacy and the efficiency of optical instruments in natural philosophy. All the figures of the dual are used, except one: the counterattack. Cavendish, indeed, was alone on the battlefield. Is it possible to call a dual a battle with only one combatant? This particular case of dispute that stops owing to the shortage of combatants is the subject of this article.

  19. Cytotoxic bibenzyl dimers from the stems of Dendrobium fimbriatum Hook.

    PubMed

    Xu, Feng-Qing; Xu, Fang-Cheng; Hou, Bo; Fan, Wei-Wei; Zi, Cheng-Ting; Li, Yan; Dong, Fa-Wu; Liu, Yu-Qing; Sheng, Jun; Zuo, Zhi-Li; Hu, Jiang-Miao

    2014-11-15

    The bioassay-guided chemical investigation of the stems of Dendrobium fimbriatum Hook led to the isolation of seven first reported bibenzyl dimers with a linkage of a methylene moiety, fimbriadimerbibenzyls A-G (1-7), together with a new dihydrophenanthrene derivative (S)-2,4,5,9-tetrahydroxy-9,10-dihydrophenanthrene (8) and thirteen known compounds (9-21). The structure of the new compound was established by spectroscopic analysis. Biological evaluation of bibenzyl derivatives against five human cell lines indicated that seven of those compounds exhibited broad-spectrum and cytotoxic activities with IC50 values ranging from 2.2 to 21.2 μM. Those rare bibenzyl dimers exhibited cytotoxic activities in vitro and the cytotoxicity decreased as the number of oxygen-containing groups in the structure decreases.

  20. Removal of diminutive colorectal polyps: A prospective randomized clinical trial between cold snare polypectomy and hot forceps biopsy

    PubMed Central

    Komeda, Yoriaki; Kashida, Hiroshi; Sakurai, Toshiharu; Tribonias, George; Okamoto, Kazuki; Kono, Masashi; Yamada, Mitsunari; Adachi, Teppei; Mine, Hiromasa; Nagai, Tomoyuki; Asakuma, Yutaka; Hagiwara, Satoru; Matsui, Shigenaga; Watanabe, Tomohiro; Kitano, Masayuki; Chikugo, Takaaki; Chiba, Yasutaka; Kudo, Masatoshi

    2017-01-01

    AIM To compare the efficacy and safety of cold snare polypectomy (CSP) and hot forceps biopsy (HFB) for diminutive colorectal polyps. METHODS This prospective, randomized single-center clinical trial included consecutive patients ≥ 20 years of age with diminutive colorectal polyps 3-5 mm from December 2014 to October 2015. The primary outcome measures were en-bloc resection (endoscopic evaluation) and complete resection rates (pathological evaluation). The secondary outcome measures were the immediate bleeding or immediate perforation rate after polypectomy, delayed bleeding or delayed perforation rate after polypectomy, use of clipping for bleeding or perforation, and polyp retrieval rate. Prophylactic clipping after polyp removal wasn’t routinely performed. RESULTS Two hundred eight patients were randomized into the CSP (102), HFB (106) and 283 polyps were evaluated (CSP: 148, HFB: 135). The en-bloc resection rate was significantly higher with CSP than with HFB [99.3% (147/148) vs 80.0% (108/135), P < 0.0001]. The complete resection rate was significantly higher with CSP than with HFB [80.4% (119/148) vs 47.4% (64/135), P < 0.0001]. The immediate bleeding rate was similar between the groups [8.6% (13/148) vs 8.1% (11/135), P = 1.000], and endoscopic hemostasis with hemoclips was successful in all cases. No cases of perforation or delayed bleeding occurred. The rate of severe tissue injury to the pathological specimen was higher HFB than CSP [52.6% (71/135) vs 1.3% (2/148), P < 0.0001]. Polyp retrieval failure was encountered CSP (7), HFB (2). CONCLUSION CSP is more effective than HFB for resecting diminutive polyps. Further long-term follow-up study is required. PMID:28127206

  1. Casual hook up sex during the first year of college: Prospective associations with attitudes about sex and love relationships.

    PubMed

    Katz, Jennifer; Schneider, Monica E

    2013-11-01

    This study examined bidirectional relationships among emerging adults' involvement in casual hook up sex and attitudes about sex and love relationships. At the start and end of their first year in college, undergraduates (N = 163) responded to measures of sexual behavior, sexual attitudes, and attitudes about love relationships. In cross-sectional analyses, attitudes about sex and love both were associated with involvement in casual hook up sex. In prospective analyses, initial attitudes about sexual instrumentality uniquely predicted involvement in later hook up sex, even after controlling for past hook up sex. Furthermore, involvement in hook up sex during the first year of college predicted greater sexual permissiveness and comfort with casual genital contact, even after controlling for initial sexual attitudes and hook up behaviors. None of the associations between attitudes and behavior were qualified by gender. Experiences of causal hook up sex appear to have implications primarily for emerging adults' attitudes about sexual interactions rather than their attitudes about love relationships.

  2. Simultaneous fracture of the waist of the scaphoid and the hook of the hamate.

    PubMed

    Komura, Shingo; Suzuki, Yasushi; Ikehata, Tatsuya

    2010-01-01

    A case of simultaneous fracture of the waist of the scaphoid and the hook of the hamate is presented. The scaphoid fracture was treated surgically with a headless compression screw, while the hook fracture was treated conservatively with cast immobilisation for eight weeks. Both fractures achieved bone union and the patient returned to work without any symptoms or complications. Only two cases of fractures of the scaphoid and hamate have been reported previously. However, both of them involved fracture of the body of the hamate. This is the first report of simultaneous fracture of the scaphoid and the hook of the hamate.

  3. A new iterative Fourier transform algorithm for optimal design in holographic optical tweezers

    NASA Astrophysics Data System (ADS)

    Memmolo, P.; Miccio, L.; Merola, F.; Ferraro, P.; Netti, P. A.

    2012-06-01

    We propose a new Iterative Fourier Transform Algorithm (IFTA) capable to suppress ghost traps and noise in Holographic Optical Tweezers (HOT), maintaining a high diffraction efficiency in a computational time comparable with the others iterative algorithms. The process consists in the planning of the suitable ideal target of optical tweezers as input of classical IFTA and we show we are able to design up to 4 real traps, in the field of view imaged by the microscope objective, using an IFTA built on fictitious phasors, located in strategic positions in the Fourier plane. The effectiveness of the proposed algorithm is evaluated both for numerical and optical reconstructions and compared with the other techniques known in literature.

  4. Identification of individual biofilm-forming bacterial cells using Raman tweezers.

    PubMed

    Samek, Ota; Bernatová, Silvie; Ježek, Jan; Šiler, Martin; Šerý, Mojmir; Krzyžánek, Vladislav; Hrubanová, Kamila; Zemánek, Pavel; Holá, Veronika; Růžička, Filip

    2015-05-01

    A method for in vitro identification of individual bacterial cells is presented. The method is based on a combination of optical tweezers for spatial trapping of individual bacterial cells and Raman microspectroscopy for acquisition of spectral “Raman fingerprints” obtained from the trapped cell. Here, Raman spectra were taken from the biofilm-forming cells without the influence of an extracellular matrix and were compared with biofilm-negative cells. Results of principal component analyses of Raman spectra enabled us to distinguish between the two strains of Staphylococcus epidermidis. Thus, we propose that Raman tweezers can become the technique of choice for a clearer understanding of the processes involved in bacterial biofilms which constitute a highly privileged way of life for bacteria, protected from the external environment.

  5. Evolution of Nanoflowers and Nanospheres of Zinc Bisporphyrinate Tweezers at the Air/water Interface.

    PubMed

    Xie, Fan; Zhuo, Congcong; Hu, Chuanjiang; Liu, Ming Hua

    2017-03-22

    While the sophisticated Langmuir and Langmuir-Blodgett technique facilitates the fabrication of uniform ultrathin monolayer and films, it is also revealed as a powerful tool for the bottom-up constructions of the nanostructures through the air/water interface. In this paper, unique nanoflowers or nanospheres were constructed based on the synthesized m-phthalic diamide-linked Zinc bis-porphyrinate tweezers using the Langmuir and Langmuir-Blodgett (LB) technique. It was found that both the two tweezer type Zinc bisporphyrinates could form stable two-dimensional spreading films at the air/water interface, which could be subsequently transferred onto solid substrates by the vertical lifting method. The atomic force microscope (AFM) revealed that at the initial spreading stage the compound formed flat disk-like domains and then hierarchically evolved into nanoflowers or nanospheres upon compressing the floating film. Such nanostructures have not been reported before and cannot be fabricated using the other self-assembly methods.

  6. Multiple Optical Traps with a Single-Beam Optical Tweezer Utilizing Surface Micromachined Planar Curved Grating

    NASA Astrophysics Data System (ADS)

    Kuo, Ju-Nan; Chen, Kuan-Yu

    2010-11-01

    In this paper, we present a single-beam optical tweezer integrated with a planar curved diffraction grating for microbead manipulation. Various curvatures of the surface micromachined planar curved grating are systematically investigated. The planar curved grating was fabricated using multiuser micro-electro-mechanical-system (MEMS) processes (MUMPs). The angular separation and the number of diffracted orders were determined. Experimental results indicate that the diffraction patterns and curvature of the planar curved grating are closely related. As the curvature of the planar curved grating increases, the vertical diffraction angle increases, resulting in the strip patterns of the planar curved grating. A single-beam optical tweezer integrated with a planar curved diffraction grating was developed. We demonstrate a technique for creating multiple optical traps from a single laser beam using the developed planar curved grating. The strip patterns of the planar curved grating that resulted from diffraction were used to trap one row of polystyrene beads.

  7. Exact Theory of Optical Tweezers and Its Application to Absolute Calibration.

    PubMed

    Dutra, Rafael S; Viana, Nathan B; Neto, Paulo A Maia; Nussenzveig, H Moysés

    2017-01-01

    Optical tweezers have become a powerful tool for basic and applied research in cell biology. Here, we describe an experimentally verified theory for the trapping forces generated by optical tweezers based on first principles that allows absolute calibration. For pedagogical reasons, the steps that led to the development of the theory over the past 15 years are outlined. The results are applicable to a broad range of microsphere radii, from the Rayleigh regime to the ray optics one, for different polarizations and trapping heights, including all commonly employed parameter domains. Protocols for implementing absolute calibration are given, explaining how to measure all required experimental parameters, and including a link to an applet for stiffness calculations.

  8. Neural Network for Image-to-Image Control of Optical Tweezers

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.; Anderson, Robert C.; Weiland, Kenneth E.; Wrbanek, Susan Y.

    2004-01-01

    A method is discussed for using neural networks to control optical tweezers. Neural-net outputs are combined with scaling and tiling to generate 480 by 480-pixel control patterns for a spatial light modulator (SLM). The SLM can be combined in various ways with a microscope to create movable tweezers traps with controllable profiles. The neural nets are intended to respond to scattered light from carbon and silicon carbide nanotube sensors. The nanotube sensors are to be held by the traps for manipulation and calibration. Scaling and tiling allow the 100 by 100-pixel maximum resolution of the neural-net software to be applied in stages to exploit the full 480 by 480-pixel resolution of the SLM. One of these stages is intended to create sensitive null detectors for detecting variations in the scattered light from the nanotube sensors.

  9. Design of Fresnel Lens-Type Multi-Trapping Acoustic Tweezers

    PubMed Central

    Tu, You-Lin; Chen, Shih-Jui; Hwang, Yean-Ren

    2016-01-01

    In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers use an ultrasound beam produced by a lead zirconate titanate (PZT) transducer operating at 2.4 MHz and 100 Vpeak-to-peak in a water medium. The design of the Fresnel lens (zone plate) is based on air reflection, acoustic impedance matching, and the Fresnel half-wave band (FHWB) theory. This acoustic Fresnel lens can produce gradient force and acoustic potential wells that allow the capture and manipulation of single particles or clusters of particles. Simulation results strongly indicate a good trapping ability, for particles under 150 µm in diameter, in the minimum energy location. This can be useful for cell or microorganism manipulation. PMID:27886050

  10. Thermophoretic Tweezers for Low-Power and Versatile Manipulation of Biological Cells.

    PubMed

    Lin, Linhan; Peng, Xiaolei; Wei, Xiaoling; Mao, Zhangming; Xie, Chong; Zheng, Yuebing

    2017-03-28

    Optical manipulation of biological cells and nanoparticles is significantly important in life sciences, early disease diagnosis, and nanomanufacturing. However, low-power and versatile all-optical manipulation has remained elusive. Herein, we have achieved light-directed versatile thermophoretic manipulation of biological cells at an optical power 100-1000 times lower than that of optical tweezers. By harnessing the permittivity gradient in the electric double layer of the charged surface of the cell membrane, we succeed at the low-power trapping of suspended biological cells within a light-controlled temperature gradient field. Furthermore, through dynamic control of optothermal potentials using a digital micromirror device, we have achieved arbitrary spatial arrangements of cells at a resolution of ∼100 nm and precise rotation of both single and assemblies of cells. Our thermophoretic tweezers will find applications in cellular biology, nanomedicine, and tissue engineering.

  11. Studying taxis in real time using optical tweezers: applications for Leishmania amazonensis parasites.

    PubMed

    Pozzo, L Y; Fontes, A; de Thomaz, A A; Santos, B S; Farias, P M A; Ayres, D C; Giorgio, S; Cesar, C L

    2009-01-01

    Beads trapped by an optical tweezers can be used as a force transducer for measuring forces of the same order of magnitude as typical forces induced by flagellar motion. We used an optical tweezers to study chemotaxis by observing the force response of a flagellated microorganism when placed in a gradient of attractive chemical substances. This report shows such observations for Leishmania amazonensis, responsible for leishmaniasis, a serious disease. We quantified the movement of this protozoan for different gradients of glucose. We were able to observe both the strength and the directionality of the force. The characterization of the chemotaxis of these parasites can help to understand the mechanics of infection and improve the treatments employed for this disease. This methodology can be used to quantitatively study the taxis of any kind of flagellated microorganisms under concentration gradients of different chemical substances, or even other types of variable gradients such as temperature and pressure.

  12. Design of Fresnel Lens-Type Multi-Trapping Acoustic Tweezers.

    PubMed

    Tu, You-Lin; Chen, Shih-Jui; Hwang, Yean-Ren

    2016-11-23

    In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers use an ultrasound beam produced by a lead zirconate titanate (PZT) transducer operating at 2.4 MHz and 100 Vpeak-to-peak in a water medium. The design of the Fresnel lens (zone plate) is based on air reflection, acoustic impedance matching, and the Fresnel half-wave band (FHWB) theory. This acoustic Fresnel lens can produce gradient force and acoustic potential wells that allow the capture and manipulation of single particles or clusters of particles. Simulation results strongly indicate a good trapping ability, for particles under 150 µm in diameter, in the minimum energy location. This can be useful for cell or microorganism manipulation.

  13. An Improved Optical Tweezers Assay for Measuring the Force Generation of Single Kinesin Molecules

    PubMed Central

    Nicholas, Matthew P.; Rao, Lu; Gennerich, Arne

    2014-01-01

    Numerous microtubule-associated molecular motors, including several kinesins and cytoplasmic dynein, produce opposing forces that regulate spindle and chromosome positioning during mitosis. The motility and force generation of these motors are therefore critical to normal cell division, and dysfunction of these processes may contribute to human disease. Optical tweezers provide a powerful method for studying the nanometer motility and piconewton force generation of single motor proteins in vitro. Using kinesin-1 as a prototype, we present a set of step-by-step, optimized protocols for expressing a kinesin construct (K560-GFP) in Escherichia coli, purifying it, and studying its force generation in an optical tweezers microscope. We also provide detailed instructions on proper alignment and calibration of an optical trapping microscope. These methods provide a foundation for a variety of similar experiments. PMID:24633799

  14. Identification of individual biofilm-forming bacterial cells using Raman tweezers

    NASA Astrophysics Data System (ADS)

    Samek, Ota; Bernatová, Silvie; Ježek, Jan; Šiler, Martin; Šerý, Mojmir; Krzyžánek, Vladislav; Hrubanová, Kamila; Zemánek, Pavel; Holá, Veronika; Růžička, Filip

    2015-05-01

    A method for in vitro identification of individual bacterial cells is presented. The method is based on a combination of optical tweezers for spatial trapping of individual bacterial cells and Raman microspectroscopy for acquisition of spectral "Raman fingerprints" obtained from the trapped cell. Here, Raman spectra were taken from the biofilm-forming cells without the influence of an extracellular matrix and were compared with biofilm-negative cells. Results of principal component analyses of Raman spectra enabled us to distinguish between the two strains of Staphylococcus epidermidis. Thus, we propose that Raman tweezers can become the technique of choice for a clearer understanding of the processes involved in bacterial biofilms which constitute a highly privileged way of life for bacteria, protected from the external environment.

  15. Low cost optical tweezers systems using double coil driving stepping motor to controlling sample stage

    NASA Astrophysics Data System (ADS)

    Laowattanatham, N.; Cheamanunkul, N.; Plaipichit, S.; Buranasiri, P.; Nuansri, R.

    2013-06-01

    In this research, the low cost optical tweezers systems using X-Y stage has been developed by using 5-phase stepping motor. By using sequential double coil driving, we can obtain the driving torque larger than using the single coil driving. The moving scale is fine resolution at 0.2 micrometer. The overall systems based on microcontroller PIC18F458 and joystick controller with LabView® graphical user interface (GUI). The mechanical damping has been included in the system for decreasing the vibrational noise. By using this method, our optical tweezers system is cheaper than the other commercial system that has been used the piezoelectric driving, and still has the same efficiency.

  16. Red blood cell membrane viscoelasticity, agglutination and zeta potential measurements with double optical tweezers

    NASA Astrophysics Data System (ADS)

    Fontes, Adriana; Fernandes, Heloise P.; Barjas-Castro, Maria L.; de Thomaz, André A.; de Ysasa Pozzo, Liliana; Barbosa, Luiz C.; Cesar, Carlos L.

    2006-02-01

    The red blood cell (RBC) viscoelastic membrane contains proteins and glycolproteins embedded in, or attached, to a fluid lipid bilayer and are negatively charged, which creates a repulsive electric (zeta) potential between the cells and prevents their aggregation in the blood stream. There are techniques, however, to decrease the zeta potential to allow cell agglutination which are the basis of most of the tests of antigen-antibody interactions in blood banks. This report shows the use of a double optical tweezers to measure RBC membrane viscosity, agglutination and zeta potential. In our technique one of the optical tweezers trap a silica bead that binds strongly to a RBC at the end of a RBCs rouleaux and, at the same time, acts as a pico-Newton force transducer, after calibration through its displacement from the equilibrium position. The other optical tweezers trap the RBC at the other end. To measure the membrane viscosity the optical force is measured as a function of the velocity between the RBCs. To measure the adhesion the tweezers are slowly displaced apart until the RBCs disagglutination happens. The RBC zeta potential is measured in two complimentary ways, by the force on the silica bead attached to a single RBC in response to an applied electric field, and the conventional way, by the measurement of terminal velocity of the RBC after released from the optical trap. These two measurements provide information about the RBC charges and, also, electrolytic solution properties. We believe this can improve the methods of diagnosis in blood banks.

  17. Optical tweezers and surface plasmon resonance combination system based on the high numerical aperture lens

    NASA Astrophysics Data System (ADS)

    Shan, Xuchen; Zhang, Bei; Lan, Guoqiang; Wang, Yiqiao; Liu, Shugang

    2015-11-01

    Biology and medicine sample measurement takes an important role in the microscopic optical technology. Optical tweezer has the advantage of accurate capture and non-pollution of the sample. The SPR(surface plasmon resonance) sensor has so many advantages include high sensitivity, fast measurement, less consumption of sample and label-free detection of biological sample that the SPR sensing technique has been used for surface topography, analysis of biochemical and immune, drug screening and environmental monitoring. If they combine, they will play an important role in the biological, chemical and other subjects. The system we propose use the multi-axis cage system, by using the methods of reflection and transmiss ion to improve the space utilization. The SPR system and optical tweezer were builtup and combined in one system. The cage of multi-axis system gives full play to its accuracy, simplicity and flexibility. The size of the system is 20 * 15 * 40 cm3 and thus the sample can be replaced to switch between the optical tweezers system and the SPR system in the small space. It means that we get the refractive index of the sample and control the particle in the same system. In order to control the revolving stage, get the picture and achieve the data stored automatically, we write a LabVIEW procedure. Then according to the data from the back focal plane calculate the refractive index of the sample. By changing the slide we can trap the particle as optical tweezer, which makes us measurement and trap the sample at the same time.

  18. Light-induced rotations of chiral birefringent microparticles in optical tweezers

    PubMed Central

    Donato, M. G.; Mazzulla, A.; Pagliusi, P.; Magazzù, A.; Hernandez, R. J.; Provenzano, C.; Gucciardi, P. G.; Maragò, O. M.; Cipparrone, G.

    2016-01-01

    We study the rotational dynamics of solid chiral and birefringent microparticles induced by elliptically polarized laser light in optical tweezers. We find that both reflection of left circularly polarized light and residual linear retardance affect the particle dynamics. The degree of ellipticity of laser light needed to induce rotations is found. The experimental results are compared with analytical calculations of the transfer of angular moment from elliptically polarized light to chiral birefringent particles. PMID:27601200

  19. A feasibility study of in vivo applications of single beam acoustic tweezers

    SciTech Connect

    Li, Ying Lee, Changyang; Chen, Ruimin; Zhou, Qifa; Shung, K. Kirk

    2014-10-27

    Tools that are capable of manipulating micro-sized objects have been widely used in such fields as physics, chemistry, biology, and medicine. Several devices, including optical tweezers, atomic force microscope, micro-pipette aspirator, and standing surface wave type acoustic tweezers have been studied to satisfy this need. However, none of them has been demonstrated to be suitable for in vivo and clinical studies. Single beam acoustic tweezers (SBAT) is a technology that uses highly focused acoustic beam to trap particles toward the beam focus. Its feasibility was first theoretically and experimentally demonstrated by Lee and Shung several years ago. Since then, much effort has been devoted to improving this technology. At present, the tool is capable of trapping a microparticle as small as 1 μm, as well as a single red blood cell. Although in comparing to other microparticles manipulating technologies, SBAT has advantages of providing stronger trapping force and deeper penetration depth in tissues, and producing less tissue damage, its potential for in vivo applications has yet been explored. It is worth noting that ultrasound has been used as a diagnostic tool for over 50 years and no known major adverse effects have been observed at the diagnostic energy level. This paper reports the results of an initial attempt to assess the feasibility of single beam acoustic tweezers to trap microparticles in vivo inside of a blood vessel. The acoustic intensity of SBAT under the trapping conditions that were utilized was measured. The mechanical index and thermal index at the focus of acoustic beam were found to be 0.48 and 0.044, respectively, which meet the standard of commercial diagnostic ultrasound system.

  20. Amyloid β-Protein Assembly: The Effect of Molecular Tweezers CLR01 and CLR03

    PubMed Central

    2015-01-01

    The early oligomerization of amyloid β-protein (Aβ) has been shown to be an important event in the pathology of Alzheimer’s disease (AD). Designing small molecule inhibitors targeting Aβ oligomerization is one attractive and promising strategy for AD treatment. Here we used ion mobility spectrometry coupled to mass spectrometry (IMS-MS) to study the different effects of the molecular tweezers CLR01 and CLR03 on Aβ self-assembly. CLR01 was found to bind to Aβ directly and disrupt its early oligomerization. Moreover, CLR01 remodeled the early oligomerization of Aβ42 by compacting the structures of dimers and tetramers and as a consequence eliminated higher-order oligomers. Unexpectedly, the negative-control derivative, CLR03, which lacks the hydrophobic arms of the tweezer structure, was found to facilitate early Aβ oligomerization. Our study provides an example of IMS as a powerful tool to study and better understand the interaction between small molecule modulators and Aβ oligomerization, which is not attainable by other methods, and provides important insights into therapeutic development of molecular tweezers for AD treatment. PMID:25751170

  1. Grating-flanked plasmonic coaxial apertures for efficient fiber optical tweezers.

    PubMed

    Saleh, Amr A E; Sheikhoelislami, Sassan; Gastelum, Steven; Dionne, Jennifer A

    2016-09-05

    Subwavelength plasmonic apertures have been foundational for direct optical manipulation of nanoscale specimens including sub-100 nm polymeric beads, metallic nanoparticles and proteins. While most plasmonic traps result in two-dimensional localization, three-dimensional manipulation has been demonstrated by integrating a plasmonic aperture on an optical fiber tip. However, such 3D traps are usually inefficient since the optical mode of the fiber and the subwavelength aperture only weakly couple. In this paper we design more efficient optical-fiber-based plasmonic tweezers combining a coaxial plasmonic aperture with a plasmonic grating coupler at the fiber tip facet. Using full-field finite difference time domain analysis, we optimize the grating design for both gold and silver fiber-based coaxial tweezers such that the optical transmission through the apertures is maximized. With the optimized grating, we show that the maximum transmission efficiency increases from 2.5% to 19.6% and from 1.48% to 16.7% for the gold and silver structures respectively. To evaluate their performance as optical tweezers, we calculate the optical forces and the corresponding trapping potential on dielectric particles interacting with the apertures. We demonstrate that the enahncement in the transmission translates into an equivalent increase in the optical forces. Consequently, the optical power required to achieve stable optical trapping is significantly reduced allowing for efficient localization and 3D manipulation of sub-30 nm dielectric particles.

  2. Stable optical trapping and sensitive characterization of nanostructures using standing-wave Raman tweezers

    NASA Astrophysics Data System (ADS)

    Wu, Mu-Ying; Ling, Dong-Xiong; Ling, Lin; Li, William; Li, Yong-Qing

    2017-02-01

    Optical manipulation and label-free characterization of nanoscale structures open up new possibilities for assembly and control of nanodevices and biomolecules. Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped particle, but is generally less effective for individual nanoparticles. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints.

  3. Stable optical trapping and sensitive characterization of nanostructures using standing-wave Raman tweezers

    PubMed Central

    Wu, Mu-ying; Ling, Dong-xiong; Ling, Lin; Li, William; Li, Yong-qing

    2017-01-01

    Optical manipulation and label-free characterization of nanoscale structures open up new possibilities for assembly and control of nanodevices and biomolecules. Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped particle, but is generally less effective for individual nanoparticles. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints. PMID:28211526

  4. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    SciTech Connect

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-15

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  5. Quantitation of malaria parasite-erythrocyte cell-cell interactions using optical tweezers.

    PubMed

    Crick, Alex J; Theron, Michel; Tiffert, Teresa; Lew, Virgilio L; Cicuta, Pietro; Rayner, Julian C

    2014-08-19

    Erythrocyte invasion by Plasmodium falciparum merozoites is an essential step for parasite survival and hence the pathogenesis of malaria. Invasion has been studied intensively, but our cellular understanding has been limited by the fact that it occurs very rapidly: invasion is generally complete within 1 min, and shortly thereafter the merozoites, at least in in vitro culture, lose their invasive capacity. The rapid nature of the process, and hence the narrow time window in which measurements can be taken, have limited the tools available to quantitate invasion. Here we employ optical tweezers to study individual invasion events for what we believe is the first time, showing that newly released P. falciparum merozoites, delivered via optical tweezers to a target erythrocyte, retain their ability to invade. Even spent merozoites, which had lost the ability to invade, retain the ability to adhere to erythrocytes, and furthermore can still induce transient local membrane deformations in the erythrocyte membrane. We use this technology to measure the strength of the adhesive force between merozoites and erythrocytes, and to probe the cellular mode of action of known invasion inhibitory treatments. These data add to our understanding of the erythrocyte-merozoite interactions that occur during invasion, and demonstrate the power of optical tweezers technologies in unraveling the blood-stage biology of malaria.

  6. Scanning a DNA Molecule for Bound Proteins Using Hybrid Magnetic and Optical Tweezers

    PubMed Central

    van Loenhout, Marijn T. J.; De Vlaminck, Iwijn; Flebus, Benedetta; den Blanken, Johan F.; Zweifel, Ludovit P.; Hooning, Koen M.; Kerssemakers, Jacob W. J.; Dekker, Cees

    2013-01-01

    The functional state of the genome is determined by its interactions with proteins that bind, modify, and move along the DNA. To determine the positions and binding strength of proteins localized on DNA we have developed a combined magnetic and optical tweezers apparatus that allows for both sensitive and label-free detection. A DNA loop, that acts as a scanning probe, is created by looping an optically trapped DNA tether around a DNA molecule that is held with magnetic tweezers. Upon scanning the loop along the λ-DNA molecule, EcoRI proteins were detected with ∼17 nm spatial resolution. An offset of 33±5 nm for the detected protein positions was found between back and forwards scans, corresponding to the size of the DNA loop and in agreement with theoretical estimates. At higher applied stretching forces, the scanning loop was able to remove bound proteins from the DNA, showing that the method is in principle also capable of measuring the binding strength of proteins to DNA with a force resolution of 0.1 pN/. The use of magnetic tweezers in this assay allows the facile preparation of many single-molecule tethers, which can be scanned one after the other, while it also allows for direct control of the supercoiling state of the DNA molecule, making it uniquely suitable to address the effects of torque on protein-DNA interactions. PMID:23755219

  7. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    NASA Astrophysics Data System (ADS)

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-01

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  8. Micro-rheology and interparticle interactions in aerosols probed with optical tweezers

    NASA Astrophysics Data System (ADS)

    Reid, Jonathan P.; Power, Rory M.; Cai, Chen; Simpson, Stephen H.

    2014-09-01

    Using optical tweezers for micro-rheological investigations of a surrounding fluid has been routinely demonstrated. In this work, we will demonstrate that rheological measurements of the bulk and surface properties of aerosol particles can be made directly using optical tweezers, providing important insights into the phase behavior of materials in confined environments and the rate of molecular diffusion in viscous phases. The use of holographic optical tweezers to manipulate aerosol particles has become standard practice in recent years, providing an invaluable tool to investigate particle dynamics, including evaporation/ condensation kinetics, chemical aging and phase transformation. When combined with non-linear Raman spectroscopy, the size and refractive index of a particle can be determined with unprecedented accuracy <+/- 0.05%). Active control of the relative positions of pairs of particles can allow studies of the coalescence of particles, providing a unique opportunity to investigate the bulk and surface properties that govern the hydrodynamic relaxation in particle shape. In particular, we will show how the viscosity and surface tension of particles can be measured directly in the under-damped regime at low viscosity. In the over-damped regime, we will show that viscosity measurements can extend close to the glass transition, allowing measurements over an impressive dynamic range of 12 orders of magnitude in relaxation timescale and viscosity. Indeed, prior to the coalescence event, we will show how the Brownian trajectories of trapped particles can yield important and unique insights into the interactions of aerosol particles.

  9. Acoustic tweezers via sub–time-of-flight regime surface acoustic waves

    PubMed Central

    Collins, David J.; Devendran, Citsabehsan; Ma, Zhichao; Ng, Jia Wei; Neild, Adrian; Ai, Ye

    2016-01-01

    Micrometer-scale acoustic waves are highly useful for refined optomechanical and acoustofluidic manipulation, where these fields are spatially localized along the transducer aperture but not along the acoustic propagation direction. In the case of acoustic tweezers, such a conventional acoustic standing wave results in particle and cell patterning across the entire width of a microfluidic channel, preventing selective trapping. We demonstrate the use of nanosecond-scale pulsed surface acoustic waves (SAWs) with a pulse period that is less than the time of flight between opposing transducers to generate localized time-averaged patterning regions while using conventional electrode structures. These nodal positions can be readily and arbitrarily positioned in two dimensions and within the patterning region itself through the imposition of pulse delays, frequency modulation, and phase shifts. This straightforward concept adds new spatial dimensions to which acoustic fields can be localized in SAW applications in a manner analogous to optical tweezers, including spatially selective acoustic tweezers and optical waveguides. PMID:27453940

  10. Mechanics of the human red blood cell deformed by optical tweezers*1

    NASA Astrophysics Data System (ADS)

    Dao, M.; Lim, C. T.; Suresh, S.

    2003-11-01

    The mechanical deformation characteristics of living cells are known to influence strongly their chemical and biological functions and the onset, progression and consequences of a number of human diseases. The mechanics of the human red blood cell (erythrocyte) subjected to large deformation by optical tweezers forms the subject of this paper. Video photography of the cell deformed in a phosphate buffered saline solution at room temperature during the imposition of controlled stretching forces, in the tens to several hundreds picoNewton range, is used to assess experimentally the deformation characteristics. The mechanical responses of the cell during loading and upon release of the optical force are then analysed to extract the elastic properties of the cell membrane by recourse to several different constitutive formulations of the elastic and viscoelastic behavior within the framework of a fully three-dimensional finite element analysis. A parametric study of various geometric, loading and structural factors is also undertaken in order to develop quantitative models for the mechanics of deformation by means of optical tweezers. The outcome of the experimental and computational analyses is then compared with the information available on the mechanical response of the red blood cell from other independent experimental techniques. Potential applications of the optical tweezers method described in this paper to the study of mechanical deformation of living cells under different stress states and in response to the progression of some diseases are also highlighted.

  11. Measurement of macrophage adhesion using optical tweezers with backward-scattered detection

    NASA Astrophysics Data System (ADS)

    Wei, Sung-Yang; Su, Yi-Jr; Shih, Po-Chen; Yang, Shih-Mo; Hsu, Long

    2010-08-01

    Macrophages are members of the leukocyte family. Tissue damage causes inflammation and release of vasoactive and chemotactic factors, which trigger a local increase in blood flow and capillary permeability. Then, leukocytes accumulate quickly to the infection site. The leukocyte extravasation process takes place according to a sequence of events that involve tethering, activation by a chemoattractant stimulus, adhesion by integrin binding, and migrating to the infection site. The leukocyte extravasation process reveals that adhesion is an important part of the immune system. Optical tweezers have become a useful tool with broad applications in biology and physics. In force measurement, the trapped bead as a probe usually uses a polystyrene bead of 1 μm diameter to measure adhesive force between the trapped beads and cell by optical tweezers. In this paper, using the ray-optics model calculated trapping stiffness and defined the linear displacement ranges. By the theoretical values of stiffness and linear displacement ranges, this study attempted to obtain a proper trapped particle size in measuring adhesive force. Finally, this work investigates real-time adhesion force measurements between human macrophages and trapped beads coated with lipopolysaccharides using optical tweezers with backscattered detection.

  12. New biodiagnostics based on optical tweezers: typing red blood cells, and identification of drug resistant bacteria

    NASA Astrophysics Data System (ADS)

    Chen, Jia-Wen; Lin, Chuen-Fu; Wang, Shyang-Guang; Lee, Yi-Chieh; Chiang, Chung-Han; Huang, Min-Hui; Lee, Yi-Hsiung; Vitrant, Guy; Pan, Ming-Jeng; Lee, Horng-Mo; Liu, Yi-Jui; Baldeck, Patrice L.; Lin, Chih-Lang

    2013-09-01

    Measurements of optical tweezers forces on biological micro-objects can be used to develop innovative biodiagnostics methods. In the first part of this report, we present a new sensitive method to determine A, B, D types of red blood cells. Target antibodies are coated on glass surfaces. Optical forces needed to pull away RBC from the glass surface increase when RBC antigens interact with their corresponding antibodies. In this work, measurements of stripping optical forces are used to distinguish the major RBC types: group O Rh(+), group A Rh(+) and group B Rh(+). The sensitivity of the method is found to be at least 16-folds higher than the conventional agglutination method. In the second part of this report, we present an original way to measure in real time the wall thickness of bacteria that is one of the most important diagnostic parameters of bacteria drug resistance in hospital diagnostics. The optical tweezers force on a shell bacterium is proportional to its wall thickness. Experimentally, we determine the optical tweezers force applied on each bacteria family by measuring their escape velocity. Then, the wall thickness of shell bacteria can be obtained after calibrating with known bacteria parameters. The method has been successfully applied to indentify, from blind tests, Methicillinresistant Staphylococcus aureus (MRSA), including VSSA (NCTC 10442), VISA (Mu 50), and heto-VISA (Mu 3)

  13. Acoustic tweezers for studying intracellular calcium signaling in SKBR-3 human breast cancer cells.

    PubMed

    Hwang, Jae Youn; Yoon, Chi Woo; Lim, Hae Gyun; Park, Jin Man; Yoon, Sangpil; Lee, Jungwoo; Shung, K Kirk

    2015-12-01

    Extracellular matrix proteins such as fibronectin (FNT) play crucial roles in cell proliferation, adhesion, and migration. For better understanding of these associated cellular activities, various microscopic manipulation tools have been used to study their intracellular signaling pathways. Recently, it has appeared that acoustic tweezers may possess similar capabilities in the study. Therefore, we here demonstrate that our newly developed acoustic tweezers with a high-frequency lithium niobate ultrasonic transducer have potentials to study intracellular calcium signaling by FNT-binding to human breast cancer cells (SKBR-3). It is found that intracellular calcium elevations in SKBR-3 cells, initially occurring on the microbead-contacted spot and then eventually spreading over the entire cell, are elicited by attaching an acoustically trapped FNT-coated microbead. Interestingly, they are suppressed by either extracellular calcium elimination or phospholipase C (PLC) inhibition. Hence, this suggests that our acoustic tweezers may serve as an alternative tool in the study of intracellular signaling by FNT-binding activities.

  14. Efficacy and safety of cryobiopsy versus forceps biopsy for interstitial lung diseases and lung tumours: A systematic review and meta-analysis.

    PubMed

    Ganganah, Oormila; Guo, Shu Liang; Chiniah, Manu; Li, Yi Shi

    2016-07-01

    Forceps biopsy (FB) is the most commonly used diagnostic tool for lung pathologies. FB is associated with a high diagnostic failure rate. Cryobiopsy (CB) is a novel technique providing a larger specimen size, few artefacts, more alveolar parts and superior diagnostic yield. CB, however, has drawbacks such as higher bleeding and pneumothorax rate. We conducted a meta-analysis to investigate the specimen area, diagnostic rate and bleeding severity in CB versus FB in interstitial lung diseases (ILDs) and lung tumours. A systematic literature search of PUBMED, BIOSIS PREVIEW and OVID databases was conducted using specific search terms. Eligible studies including RCTs and non-RCTs comparing cryobiopsy/cryotransbronchial biopsy (CB/CTBB) and forceps biopsy/forceps transbronchial biopsy (FB/FTBB) for specimen area, diagnostic rate and bleeding rate in ILDs and lung tumours were analysed. Two reviewers independently extracted data and evaluated the quality of the studies. Eight studies involving 916 patients were analysed. Specimen area (mm(2) ) was significantly larger in CB/CTBB than FB/FTBB (standard mean difference = 1.21, 95% confidence interval (0.94, 1.48), P < 0.00001). The diagnostic rate was significantly higher in CB/CTBB than FB/FTBB (Risk ratio 1.36, 95% confidence interval (1.16, 1.59), P = 0.0002). Three studies compared the bleeding severity with only one showing significantly more bleeding in CB. Cryobiopsy/cryotransbronchial shows superiority to FB/FTBB for specimen area and diagnostic rate. CB/CTBB has better efficacy over FB/FTBB.

  15. VISIT BY CONGRESSIONAL REPRESENTATIVES - HONORABLE FRANK E HOOK MICHIGAN - HONORABLE THAD E WASIELEW

    NASA Technical Reports Server (NTRS)

    1946-01-01

    VISIT BY CONGRESSIONAL REPRESENTATIVES - HONORABLE FRANK E HOOK MICHIGAN - HONORABLE THAD E WASIELEWSKI WISCONSIN - R SESSIONS NACA - HONORABLE MICHAEL A FEIGHAN OHIO - CAPTAIN VICTOR H HARDING CHIEF DEPUTY SARGEANT AT ARMS FOR THE

  16. Structural study and geochronology in the Hook Batholith, Central Zambia

    NASA Astrophysics Data System (ADS)

    Naydenov, K.; Lehmann, J.; Saalmann, K.; Milani, L.; Kinnaird, J.; Charlesworth, G.; Frei, D.

    2013-12-01

    The Pan-African Hook batholith is emplaced N of the Mwembeshi dislocation, a regional scale structure at the contact between Zambezi Belt and Lufilian Arc in Central Zambia. Exposed over 12000 km2 the batholith is composed mainly of fine-grained and coarse-grained porphyritic granites and leucogranites affected by solid-state deformation along high-strain zones. Two main zones of deformation were investigated - the Itezhi-Tezhi Zone (ITZ) in the SW part of the batholith and the Nalusanga Zone (NZ) to the NE. The 2.5 km wide, N-S trending, subvertical ITZ is a medium-grade, pure shear dominated structure, reflecting probably regional scale E-W shortening. In the central part of the zone, augen-gneiss textures developed. Mineral lineations plunging ~40° S are recorded occasionally. The deformed feldspar porphyroclasts show symmetrical tails and rarely sinistral stair-stepping. In the SE part of the Hook batholith the continuation of the ITZ trends E-W. This orientation can be explained by rotation of the original ITZ trend by N-S shortening that also has been recorded in the siliciclastic metasediments S of the contact. S dipping, up to 15 cm wide thrust zones observed in the ITZ area were probably formed during this tectonic event. The 3 km wide NZ is a subvertical to steeply SSW dipping structure, parallel to the NE contact of the batholith, with well-developed foliation and mineral stretching lineations. Field and microstructural analyses defined the NZ as a medium-grade, non-coaxial, sinistral strike-slip shear zone. The transition from weak foliated granite to S-C mylonites and ultramylonites was observed. The sinistral shearing is consistent with E-W shortening in agreement with the tectonic framework of the ITZ. The low grade metasediments to the E of the granite are folded in N to NNW trending structures also implying E-W shortening. Temperature conditions during the deformation in ITZ and NZ inferred from microstructural analyses are about 500°-550°C. The

  17. HookA is a novel dynein–early endosome linker critical for cargo movement in vivo

    PubMed Central

    Zhang, Jun; Qiu, Rongde; Arst, Herbert N.; Peñalva, Miguel A.

    2014-01-01

    Cytoplasmic dynein transports membranous cargoes along microtubules, but the mechanism of dynein–cargo interaction is unclear. From a genetic screen, we identified a homologue of human Hook proteins, HookA, as a factor required for dynein-mediated early endosome movement in the filamentous fungus Aspergillus nidulans. HookA contains a putative N-terminal microtubule-binding domain followed by coiled-coil domains and a C-terminal cargo-binding domain, an organization reminiscent of cytoplasmic linker proteins. HookA–early endosome interaction occurs independently of dynein–early endosome interaction and requires the C-terminal domain. Importantly, HookA interacts with dynein and dynactin independently of HookA–early endosome interaction but dependent on the N-terminal part of HookA. Both dynein and the p25 subunit of dynactin are required for the interaction between HookA and dynein–dynactin, and loss of HookA significantly weakens dynein–early endosome interaction, causing a virtually complete absence of early endosome movement. Thus, HookA is a novel linker important for dynein–early endosome interaction in vivo. PMID:24637327

  18. A Model of Differential Growth-Guided Apical Hook Formation in Plants.

    PubMed

    Žádníková, Petra; Wabnik, Krzysztof; Abuzeineh, Anas; Gallemi, Marçal; Van Der Straeten, Dominique; Smith, Richard S; Inzé, Dirk; Friml, Jiří; Prusinkiewicz, Przemysław; Benková, Eva

    2016-10-01

    Differential cell growth enables flexible organ bending in the presence of environmental signals such as light or gravity. A prominent example of the developmental processes based on differential cell growth is the formation of the apical hook that protects the fragile shoot apical meristem when it breaks through the soil during germination. Here, we combined in silico and in vivo approaches to identify a minimal mechanism producing auxin gradient-guided differential growth during the establishment of the apical hook in the model plant Arabidopsis thaliana Computer simulation models based on experimental data demonstrate that asymmetric expression of the PIN-FORMED auxin efflux carrier at the concave (inner) versus convex (outer) side of the hook suffices to establish an auxin maximum in the epidermis at the concave side of the apical hook. Furthermore, we propose a mechanism that translates this maximum into differential growth, and thus curvature, of the apical hook. Through a combination of experimental and in silico computational approaches, we have identified the individual contributions of differential cell elongation and proliferation to defining the apical hook and reveal the role of auxin-ethylene crosstalk in balancing these two processes.

  19. Hormonal networks involved in apical hook development in darkness and their response to light

    PubMed Central

    Mazzella, Maria A.; Casal, Jorge J.; Muschietti, Jorge P.; Fox, Ana R.

    2013-01-01

    In darkness, the dicot seedlings produce an apical hook as result of differential cell division and extension at opposite sides of the hypocotyl. This hook protects the apical meristem from mechanical damage during seedling emergence from the soil. In darkness, gibberellins act via the DELLA-PIF (PHYTOCHROME INTERACTING FACTORs) pathway, and ethylene acts via the EIN3/EIL1 (ETHYLENE INSENSITIVE 3/EIN3 like 1)-HLS1 (HOOKLESS 1) pathway to control the asymmetric accumulation of auxin required for apical hook formation and maintenance. These core pathways form a network with multiple points of connection. Light perception by phytochromes and cryptochromes reduces the activity of PIFs and (COP1) CONSTITUTIVE PHOTOMORPHOGENIC 1—both required for hook formation in darkness—, lowers the levels of gibberellins, and triggers hook opening as a component of the switch between heterotrophic and photoautotrophic development. Apical hook opening is thus a suitable model to study the convergence of endogenous and exogenous signals on the control of cell division and cell growth. PMID:24616725

  20. Identical folds used for distinct mechanical functions of the bacterial flagellar rod and hook

    PubMed Central

    Fujii, Takashi; Kato, Takayuki; Hiraoka, Koichi D.; Miyata, Tomoko; Minamino, Tohru; Chevance, Fabienne F. V.; Hughes, Kelly T.; Namba, Keiichi

    2017-01-01

    The bacterial flagellum is a motile organelle driven by a rotary motor, and its axial portions function as a drive shaft (rod), a universal joint (hook) and a helical propeller (filament). The rod and hook are directly connected to each other, with their subunit proteins FlgG and FlgE having 39% sequence identity, but show distinct mechanical properties; the rod is straight and rigid as a drive shaft whereas the hook is flexible in bending as a universal joint. Here we report the structure of the rod and comparison with that of the hook. While these two structures have the same helical symmetry and repeat distance and nearly identical folds of corresponding domains, the domain orientations differ by ∼7°, resulting in tight and loose axial subunit packing in the rod and hook, respectively, conferring the rigidity on the rod and flexibility on the hook. This provides a good example of versatile use of a protein structure in biological organisms. PMID:28120828

  1. Determining the structure-mechanics relationships of dense microtubule networks with confocal microscopy and magnetic tweezers-based microrheology.

    PubMed

    Yang, Yali; Valentine, Megan T

    2013-01-01

    The microtubule (MT) cytoskeleton is essential in maintaining the shape, strength, and organization of cells. Its spatiotemporal organization is fundamental for numerous dynamic biological processes, and mechanical stress within the MT cytoskeleton provides an important signaling mechanism in mitosis and neural development. This raises important questions about the relationships between structure and mechanics in complex MT structures. In vitro, reconstituted cytoskeletal networks provide a minimal model of cell mechanics while also providing a testing ground for the fundamental polymer physics of stiff polymer gels. Here, we describe our development and implementation of a broad tool kit to study structure-mechanics relationships in reconstituted MT networks, including protocols for the assembly of entangled and cross-linked MT networks, fluorescence imaging, microstructure characterization, construction and calibration of magnetic tweezers devices, and mechanical data collection and analysis. In particular, we present the design and assembly of three neodymium iron boron (NdFeB)-based magnetic tweezers devices optimized for use with MT networks: (1) high-force magnetic tweezers devices that enable the application of nano-Newton forces and possible meso- to macroscale materials characterization; (2) ring-shaped NdFeB-based magnetic tweezers devices that enable oscillatory microrheology measurements; and (3) portable magnetic tweezers devices that enable direct visualization of microscale deformation in soft materials under applied force.

  2. Quantum Hooke's Law to classify pulse laser induced ultrafast melting

    DOE PAGES

    Hu, Hao; Ding, Hepeng; Liu, Feng

    2015-02-03

    Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material's behavior manifesting the complexity of light-matter interaction. There exist two types of such phase transitions: one occurs at a time scale shorter than a picosecond via a nonthermal process mediated by electron-hole plasma formation; the other at a longer time scale via a thermal melting process mediated by electron-phonon interaction. However, it remains unclear what material would undergo which process and why? Here, by exploiting the property of quantum electronic stress (QES) governed by quantum Hooke's law, we classify the transitions by two distinct classes ofmore » materials: the faster nonthermal process can only occur in materials like ice having an anomalous phase diagram characterized with dTm/dP < 0, where Tm is the melting temperature and P is pressure, above a high threshold laser fluence; while the slower thermal process may occur in all materials. Especially, the nonthermal transition is shown to be induced by the QES, acting like a negative internal pressure, which drives the crystal into a “super pressing” state to spontaneously transform into a higher-density liquid phase. Our findings significantly advance fundamental understanding of ultrafast crystal-to-liquid phase transitions, enabling quantitative a priori predictions.« less

  3. Quantum Hooke's Law to classify pulse laser induced ultrafast melting

    SciTech Connect

    Hu, Hao; Ding, Hepeng; Liu, Feng

    2015-02-03

    Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material's behavior manifesting the complexity of light-matter interaction. There exist two types of such phase transitions: one occurs at a time scale shorter than a picosecond via a nonthermal process mediated by electron-hole plasma formation; the other at a longer time scale via a thermal melting process mediated by electron-phonon interaction. However, it remains unclear what material would undergo which process and why? Here, by exploiting the property of quantum electronic stress (QES) governed by quantum Hooke's law, we classify the transitions by two distinct classes of materials: the faster nonthermal process can only occur in materials like ice having an anomalous phase diagram characterized with dTm/dP < 0, where Tm is the melting temperature and P is pressure, above a high threshold laser fluence; while the slower thermal process may occur in all materials. Especially, the nonthermal transition is shown to be induced by the QES, acting like a negative internal pressure, which drives the crystal into a “super pressing” state to spontaneously transform into a higher-density liquid phase. Our findings significantly advance fundamental understanding of ultrafast crystal-to-liquid phase transitions, enabling quantitative a priori predictions.

  4. Automation Hooks Architecture Trade Study for Flexible Test Orchestration

    NASA Technical Reports Server (NTRS)

    Lansdowne, Chatwin A.; Maclean, John R.; Graffagnino, Frank J.; McCartney, Patrick A.

    2010-01-01

    We describe the conclusions of a technology and communities survey supported by concurrent and follow-on proof-of-concept prototyping to evaluate feasibility of defining a durable, versatile, reliable, visible software interface to support strategic modularization of test software development. The objective is that test sets and support software with diverse origins, ages, and abilities can be reliably integrated into test configurations that assemble and tear down and reassemble with scalable complexity in order to conduct both parametric tests and monitored trial runs. The resulting approach is based on integration of three recognized technologies that are currently gaining acceptance within the test industry and when combined provide a simple, open and scalable test orchestration architecture that addresses the objectives of the Automation Hooks task. The technologies are automated discovery using multicast DNS Zero Configuration Networking (zeroconf), commanding and data retrieval using resource-oriented Restful Web Services, and XML data transfer formats based on Automatic Test Markup Language (ATML). This open-source standards-based approach provides direct integration with existing commercial off-the-shelf (COTS) analysis software tools.

  5. Three-dimensional image and spatial spectrum analysis of behavior of small animal erythrocytes in optical tweezers

    NASA Astrophysics Data System (ADS)

    Chen, Hui Chi; Shen, Wen-Tai; Kong, Yu-Han; Chuang, Chun-Hao

    2008-02-01

    Because of the softness of membrane, erythrocytes (red blood cell, RBC) have different shapes while being immersed in buffer with different osmotic pressure. While affecting by different viruses and illnesses, RBC may change its shape, or its membrane may become rigid. Moreover, RBC will ford and stretch when it is trapped by optical tweezers. Therefore, the behaviors of RBC in optical tweezers raise more discussion. In this report, we set up an optical tweezers to trap RBC of small animals like feline and canine. By adding a long working distance objective to collect the side-viewing image, a 3-D image system was constructed to detect the motion of trapped RBC. To improve the image quality for side-view, an aperture and narrow glass plate were used. From the video of these images and their spatial spectrum, the shape of trapped RBC was studied.

  6. The design and biological applications of dual-beam oscillating optical tweezer-based imaging cytorheometer

    NASA Astrophysics Data System (ADS)

    Ou-Yang, H. D.; Wang, J.

    2006-08-01

    Because of its non-invasive nature, optical tweezers have emerged as a popular tool for the studies of complex fluids and biological cells and tissues. The capabilities of optical tweezer-based experimental instruments continue to evolve for better and broader applications, through new apparatus designs and integrations with microscopic imaging techniques. In this paper, we present the design, calibration and applications of a powerful microrheometer that integrates a novel high temporal and spatial resolution dual-beam oscillating optical tweezer-based cytorheometer (DOOTC) with spinning disk confocal microscopy. The oscillating scheme detects the position of micron-size probe particles via a phase-sensitive lock-in amplifier to greatly enhance sensitivity. The dual-beam scheme ensures that the cytorheometer is insensitive to sample specimen background parameter variances, and thus enables the investigation of micromechanical properties of biological samples, which are intrinsically inhomogeneous. The cytorheometer system is demonstrated to be capable of measuring dynamic local mechanical moduli in the frequency range of 0.1-150 Hz at up to 2 data point per second and with nanometer spatial resolutions, while visualizing and monitoring structural properties in situ. We report the results of system applications in the studies of bovine skin gelatin gel, purified microtubule assemblies, and human alveolar epithelial cells. The time evolution of the storage moduli G' and the loss moduli G'' of the gel is recorded for undisturbed gel-forming process with high temporal resolution. The micromechanical modulus G* of polymerized microtubule network as a function of frequency are shown to be both inhomogeneous and anisotropic consistent with local structures revealed by confocal imaging. The mechanical properties of A549 human lung cells as a function of temperature will be reported showing significant decrease in cell stiffness at higher temperature.

  7. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads

    SciTech Connect

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim

    2015-04-15

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm{sup 2}, a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle’s position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

  8. Optical macro-tweezers: trapping of highly motile micro-organisms

    NASA Astrophysics Data System (ADS)

    Thalhammer, G.; Steiger, R.; Bernet, S.; Ritsch-Marte, M.

    2011-04-01

    Optical micromanipulation stands for contact-free handling of microscopic particles by light. Optical forces can manipulate non-absorbing objects in a large range of sizes, e.g., from biological cells down to cold atoms. Recently much progress has been made going from the micro- down to the nanoscale. Less attention has been paid to going the other way, trapping increasingly large particles. Optical tweezers typically employ a single laser beam tightly focused by a microscope objective of high numerical aperture to stably trap a particle in three dimensions (3D). As the particle size increases, stable 3D trapping in a single-beam trap requires scaling up the optical power, which eventually induces adverse biological effects. Moreover, the restricted field of view of standard optical tweezers, dictated by the use of high NA objectives, is particularly unfavorable for catching actively moving specimens. Both problems can be overcome by traps with counter-propagating beams. Our 'macro-tweezers' are especially designed to trap highly motile organisms, as they enable three-dimensional all-optical trapping and guiding in a volume of 2 × 1 × 2 mm3. Here we report for the first time the optical trapping of large actively swimming organisms, such as for instance Euglena protists and dinoflagellates of up to 70 µm length. Adverse bio-effects are kept low since trapping occurs outside high intensity regions, e.g., focal spots. We expect our approach to open various possibilities in the contact-free handling of 50-100 µm sized objects that could hitherto not be envisaged, for instance all-optical holding of individual micro-organisms for taxonomic identification, selective collecting or tagging.

  9. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads.

    PubMed

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim

    2015-04-01

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm(2), a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle's position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

  10. Closeup of QF-106 release hook for Eclipse program

    NASA Technical Reports Server (NTRS)

    1997-01-01

    View of the release hook on the QF-106 that allowed the pilot to release the tow rope extending from the C-141A tow plane in the Eclipse project. In 1997 and 1998, the Dryden Flight Research Center at Edwards, California, supported and hosted a Kelly Space & Technology, Inc. project called Eclipse, which sought to demonstrate the feasibility of a reusable tow-launch vehicle concept. The project goal was to successfully tow, inflight, a modified QF-106 delta-wing aircraft with an Air Force C-141A transport aircraft. This would demonstrate the possibility of towing and launching an actual launch vehicle from behind a tow plane. Dryden was the responsible test organization and had flight safety responsibility for the Eclipse project. Dryden provided engineering, instrumentation, simulation, modification, maintenance, range support, and research pilots for the test program. The Air Force Flight Test Center (AFFTC), Edwards, California, supplied the C-141A transport aircraft and crew and configured the aircraft as needed for the tests. The AFFTC also provided the concept and detail design and analysis as well as hardware for the tow system and QF-106 modifications. Dryden performed the modifications to convert the QF-106 drone into the piloted EXD-01 (Eclipse eXperimental Demonstrator-01) experimental aircraft. Kelly Space & Technology hoped to use the results gleaned from the tow test in developing a series of low-cost, reusable launch vehicles. These tests demonstrated the validity of towing a delta-wing aircraft having high wing loading, validated the tow simulation model, and demonstrated various operational procedures, such as ground processing of in-flight maneuvers and emergency abort scenarios.

  11. Programmable manipulation of motile cells in optoelectronic tweezers using a grayscale image

    NASA Astrophysics Data System (ADS)

    Choi, Wonjae; Nam, Seong-Won; Hwang, Hyundoo; Park, Sungsu; Park, Je-Kyun

    2008-10-01

    This paper describes a grayscale optoelectronic tweezers (OET) which allows adjustment of the electric field strength at each position of OET. A grayscale light image was used to pattern vertical electric field strength on an OET. As an electric field depends on the brightness at each point, the brighter light patterns generate the stronger electric field in the OET. Its feasibility for application to cell manipulation was demonstrated by aligning highly motile protozoan cells in vertical direction. Depending on the brightness of each pixel, the behaviors of aligned cells varied due to the different electric field strength to each cell.

  12. Raman tweezers spectroscopy study of free radical induced oxidative stress leading to eryptosis

    NASA Astrophysics Data System (ADS)

    Barkur, Surekha; Bankapur, Aseefhali; Chidangil, Santhosh

    2016-11-01

    Raman tweezers spectroscopy study of effect of free radicals was carried out on erythrocytes. We prepared hydroxyl radicals using Fenton reaction (which yields hydroxyl radicals). Raman spectra were acquired from single, trapped erythrocytes after supplementing with these free radicals. The changes in the Raman bands such as 1211 cm-1, 1224 cm-1, 1375 cm-1 indicate deoxygenation of red blood cells (RBCs). Our study shows that free radicals can induce oxidative stress on erythrocytes. The changes in the Raman spectra as well as shape of erythrocytes indicate that oxidative stress can trigger eryptosis in erythrocytes.

  13. Temporal response of three-dimensional biological cells to high-frequency optical jumping tweezers

    NASA Astrophysics Data System (ADS)

    Yu, Lingyao; Sheng, Yunlong

    2015-01-01

    We analyzed the temporal responses of biological cells in the jumping optical tweezers for tugging, wiggling, and stretching the cells in the time-sharing regime with the finite-element method. We showed that the jumping of local stress and local strain is independently omnipresent on the recovery time of the viscoelastic material and the jumping frequency of the load. We demonstrated that the elongation of a three-dimensional (3-D) viscoelastic object under a jumping load cannot be evaluated using the one-dimensional spring-dashpot material model without considering its 3-D structure.

  14. Temporal response of biological cells to high-frequency optical jumping and vibrating tweezers

    NASA Astrophysics Data System (ADS)

    Yu, Lingyao; Sheng, Yunlong

    2014-09-01

    We analyzed the temporal responses of biological cells in the jumping and vibrating optical tweezers for tugging, wiggling and stretching the cells with the finite element method. Some new concepts were established, which might be investigated in the future experiments, such as the jumping of local stress and local strain, independently on the recovery time of the viscoelastic material and on the jumping frequency, the energy dissipation in the hysteresis cycles, the cytoplasm fluid field and its interaction with the cell membrane. The cell was modeled with full 3D structure and viscoelastic continuum materials.

  15. Simultaneous Single-Molecule Force and Fluorescence Sampling of DNA Nanostructure Conformations Using Magnetic Tweezers.

    PubMed

    Kemmerich, Felix E; Swoboda, Marko; Kauert, Dominik J; Grieb, M Svea; Hahn, Steffen; Schwarz, Friedrich W; Seidel, Ralf; Schlierf, Michael

    2016-01-13

    We present a hybrid single-molecule technique combining magnetic tweezers and Förster resonance energy transfer (FRET) measurements. Through applying external forces to a paramagnetic sphere, we induce conformational changes in DNA nanostructures, which are detected in two output channels simultaneously. First, by tracking a magnetic bead with high spatial and temporal resolution, we observe overall DNA length changes along the force axis. Second, the measured FRET efficiency between two fluorescent probes monitors local conformational changes. The synchronized orthogonal readout in different observation channels will facilitate deciphering the complex mechanisms of biomolecular machines.

  16. Optical tweezers study of red blood cell aggregation and disaggregation in plasma and protein solutions.

    PubMed

    Lee, Kisung; Kinnunen, Matti; Khokhlova, Maria D; Lyubin, Evgeny V; Priezzhev, Alexander V; Meglinski, Igor; Fedyanin, Andrey A

    2016-03-01

    Kinetics of optical tweezers (OT)-induced spontaneous aggregation and disaggregation of red blood cells (RBCs) were studied at the level of cell doublets to assess RBC interaction mechanics. Measurements were performed under in vitro conditions in plasma and fibrinogen and fibrinogen + albumin solutions. The RBC spontaneous aggregation kinetics was found to exhibit different behavior depending on the cell environment. In contrast, the RBC disaggregation kinetics was similar in all solutions qualitatively and quantitatively, demonstrating a significant contribution of the studied proteins to the process. The impact of the study on assessing RBC interaction mechanics and the protein contribution to the reversible RBC aggregation process is discussed.

  17. Optical tweezers study of red blood cell aggregation and disaggregation in plasma and protein solutions

    NASA Astrophysics Data System (ADS)

    Lee, Kisung; Kinnunen, Matti; Khokhlova, Maria D.; Lyubin, Evgeny V.; Priezzhev, Alexander V.; Meglinski, Igor; Fedyanin, Andrey A.

    2016-03-01

    Kinetics of optical tweezers (OT)-induced spontaneous aggregation and disaggregation of red blood cells (RBCs) were studied at the level of cell doublets to assess RBC interaction mechanics. Measurements were performed under in vitro conditions in plasma and fibrinogen and fibrinogen + albumin solutions. The RBC spontaneous aggregation kinetics was found to exhibit different behavior depending on the cell environment. In contrast, the RBC disaggregation kinetics was similar in all solutions qualitatively and quantitatively, demonstrating a significant contribution of the studied proteins to the process. The impact of the study on assessing RBC interaction mechanics and the protein contribution to the reversible RBC aggregation process is discussed.

  18. The Cryptococcus neoformans capsule: lessons from the use of optical tweezers and other biophysical tools

    PubMed Central

    Pontes, Bruno; Frases, Susana

    2015-01-01

    The fungal pathogen Cryptococcus neoformans causes life-threatening infections in immunocompromised individuals, representing one of the leading causes of morbidity and mortality in AIDS patients. The main virulence factor of C. neoformans is the polysaccharide capsule; however, many fundamental aspects of capsule structure and function remain poorly understood. Recently, important capsule properties were uncovered using optical tweezers and other biophysical techniques, including dynamic and static light scattering, zeta potential and viscosity analysis. This review provides an overview of the latest findings in this emerging field, explaining the impact of these findings on our understanding of C. neoformans biology and resistance to host immune defenses. PMID:26157436

  19. A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

    PubMed Central

    2016-01-01

    Summary This review summarizes part of the author’s research in the area of supramolecular chemistry, beginning with his early life influences and early career efforts in molecular recognition, especially molecular tweezers. Although designed to complex DNA, these hosts proved more applicable to the field of host–guest chemistry. This early experience and interest in intercalation ultimately led to the current efforts to develop small molecule therapeutic agents for myotonic dystrophy using a rational design approach that heavily relies on principles of supramolecular chemistry. How this work was influenced by that of others in the field and the evolution of each area of research is highlighted with selected examples. PMID:26877815

  20. Laser-induced fusion of human embryonic stem cells with optical tweezers

    SciTech Connect

    Chen Shuxun; Wang Xiaolin; Sun Dong; Cheng Jinping; Han Cheng, Shuk; Kong, Chi-Wing; Li, Ronald A.

    2013-07-15

    We report a study on the laser-induced fusion of human embryonic stem cells (hESCs) at the single-cell level. Cells were manipulated by optical tweezers and fused under irradiation with pulsed UV laser at 355 nm. Successful fusion was indicated by green fluorescence protein transfer. The influence of laser pulse energy on the fusion efficiency was investigated. The fused products were viable as gauged by live cell staining. Successful fusion of hESCs with somatic cells was also demonstrated. The reported fusion outcome may facilitate studies of cell differentiation, maturation, and reprogramming.

  1. Optoelectronic Tweezers as a Tool for Parallel Single-Cell Manipulation and Stimulation

    PubMed Central

    Valley, Justin K.; Ohta, Aaron T.; Hsu, Hsan-Yin; Neale, Steven L.; Jamshidi, Arash; Wu, Ming C.

    2010-01-01

    Optoelectronic tweezers (OET) is a promising approach for the parallel manipulation of single cells for a variety of biological applications. By combining the manipulation capabilities of OET with other relevant biological techniques (such as cell lysis and electroporation), one can realize a true parallel, single-cell diagnostic and stimulation tool. Here, we demonstrate the utility of the OET device by integrating it onto single-chip systems capable of performing in-situ, electrode-based electroporation/lysis, individual cell, light-induced lysis, and light-induced electroporation. PMID:20543904

  2. Effect of Surface Layer on Electromechanical Stability of Tweezers and Cantilevers Fabricated from Conductive Cylindrical Nanowires

    NASA Astrophysics Data System (ADS)

    Keivani, Maryam; Koochi, Ali; Sedighi, Hamid M.; Abadyan, Mohamadreza; Farrokhabadi, Amin; Shahedin, Abed Moheb

    2016-12-01

    Herein, the impact of surface layer on the stability of nanoscale tweezers and cantilevers fabricated from nanowires with cylindrical cross section is studied. A modified continuum based on the Gurtin-Murdoch surface elasticity is applied for incorporating the presence of surface layer. Considering the cylindrical geometry of the nanowire, the presence of the Coulomb attraction and dispersion forces are incorporated in the derived formulations. Three different approaches, i.e. numerical differential quadrature method (DQM), an approximated homotopy perturbation method (HPM) and developing lumped parameter model (LPM) have been employed to solve the governing equations. The impact of surface layer on the instability of the system is demonstrated.

  3. Measuring stall forces in vivo with optical tweezers through light momentum changes

    NASA Astrophysics Data System (ADS)

    Mas, J.; Farré, A.; López-Quesada, C.; Fernández, X.; Martín-Badosa, E.; Montes-Usategui, M.

    2011-10-01

    The stall forces of processive molecular motors have been widely studied previously in vitro. Even so, in vivo experiments are required for determining the actual performance of each molecular motor in its natural environment. We report the direct measurement of light momentum changes in single beam optical tweezers as a suitable technique for measuring forces inside living cells, where few alternatives exist. The simplicity of this method, which does not require force calibration for each trapped object, makes it convenient for measuring the forces involved in fast dynamic biological processes such us intracellular traffic. Here we present some measurements of the stall force of processive molecular motors inside living Allium cepa cells.

  4. Quantitative characterization for dielectrophoretic behavior of biological cells using optical tweezers

    NASA Astrophysics Data System (ADS)

    Park, In Soo; Hee Park, Se; Woo Lee, Sang; Sung Yoon, Dae; Kim, Beop-Min

    2014-02-01

    We report a method to precisely quantify dielectrophoretic (DEP) forces and cutoff frequencies (fc) of viable and nonviable yeast cells. The method consists of a two-step process in which generated DEP forces act upon a cell through a micro-electrode device, followed by direct measurement of DEP forces using optical tweezers. DEP behaviors of viable and nonviable yeast cells are monitored as a function of AC frequency. We believe that the proposed method can be used as a powerful platform for cell-based assays to characterize the DEP behavior of various cell types including cancer and normal cells.

  5. Polymeric optical fiber tweezers as a tool for single cell micro manipulation and sensing

    NASA Astrophysics Data System (ADS)

    Rodrigues Ribeiro, R. S.; Soppera, O.; Guerreiro, A.; Jorge, P. A...

    2015-09-01

    In this paper a new type of polymeric fiber optic tweezers for single cell manipulation is reported. The optical trapping of a yeast cell using a polymeric micro lens fabricated by guided photo polymerization at the fiber tip is demonstrated. The 2D trapping of the yeast cells is analyzed and maximum optical forces on the pN range are calculated. The experimental results are supported by computational simulations using a FDTD method. Moreover, new insights on the potential for simultaneous sensing and optical trapping, are presented.

  6. Laser-induced fusion of human embryonic stem cells with optical tweezers

    NASA Astrophysics Data System (ADS)

    Chen, Shuxun; Cheng, Jinping; Kong, Chi-Wing; Wang, Xiaolin; Han Cheng, Shuk; Li, Ronald A.; Sun, Dong

    2013-07-01

    We report a study on the laser-induced fusion of human embryonic stem cells (hESCs) at the single-cell level. Cells were manipulated by optical tweezers and fused under irradiation with pulsed UV laser at 355 nm. Successful fusion was indicated by green fluorescence protein transfer. The influence of laser pulse energy on the fusion efficiency was investigated. The fused products were viable as gauged by live cell staining. Successful fusion of hESCs with somatic cells was also demonstrated. The reported fusion outcome may facilitate studies of cell differentiation, maturation, and reprogramming.

  7. Applications of Optical Tweezers and an Integrated Force Measurement Module for Biomedical Research

    DTIC Science & Technology

    2000-07-01

    away from the bead trapped in the tweezers by moving the DC motor -driven microscope stage rightward. The bead (A) and its diffraction pattern (B...the cell by moving the DC motor -driven stage rightward at a constant velocity of -I micron/sec. There was a membrane tether (not shown at this focal...motion driven by the DC - motor . Using fluid flow assay, we estimated that the maximal force our experimental configuration could exert was -12pN on a

  8. Surface-enhanced resonance Raman scattering in optical tweezers using co-axial second harmonic generation.

    PubMed

    Jordan, Pamela; Cooper, Jon; McNay, Graeme; Docherty, Frances; Graham, Duncan; Smith, W; Sinclair, Gavin; Padgett, Miles

    2005-05-30

    Silica particles were partially coated with silver, and a suitable chromophore, such that they could be simultaneously trapped within an optical tweezers system, and emit a surface-enhanced resonance Raman scattering (SERRS) response. A standard 1064 nm TEM00 mode laser was used to trap the bead whilst a frequency doubling crystal inserted into the beam gave several microwatts of 532 nm co-linear light to excite the SERRS emission. The con fi guration has clear applications in providing apparatus that can simultaneously manipulate a particle whilst obtaining surface sensitive sensory information.

  9. No evidence of sperm conjugate formation in an Australian mouse bearing sperm with three hooks

    PubMed Central

    Firman, Renée C; Bentley, Blair; Bowman, Faye; Marchant, Fernando García-Solís; Parthenay, Jahmila; Sawyer, Jessica; Stewart, Tom; O'Shea, James E

    2013-01-01

    Sperm conjugation occurs when two or more sperm physically unite for motility or transport through the female reproductive tract. In many muroid rodent species, sperm conjugates have been shown to form by a single, conspicuous apical hook located on the sperm head. These sperm “trains” have been reported to be highly variable in size and, despite all the heads pointing in roughly the same direction, exhibit a relatively disordered arrangement. In some species, sperm “trains” have been shown to enhance sperm swimming speed, and thus have been suggested to be advantageous in sperm competition. Here, we assessed the behavior of sperm in the sandy inland mouse (Pseudomys hermannsburgensis), a muroid rodent that bears sperm with three apical hooks. First, we accrued genetic evidence of multiple paternity within “wild” litters to unequivocally show that sperm competition does occur in this species. Following this we utilized both in vitro and in vivo methodologies to determine whether sandy inland mouse sperm conjugate to form motile trains. Our observations of in vitro preparations of active sperm revealed that sandy inland mouse sperm exhibit rapid, progressive motility as individual cells only. Similarly, histological sections of the reproductive tracts of mated females revealed no in vivo evidence of sperm conjugate formation. We conclude that the unique, three-hooked morphology of the sandy inland mouse sperm does not facilitate the formation of motile conjugates, and discuss our findings in relation to the different hypotheses for the evolution of the muroid rodent hook/s. PMID:23919134

  10. The influence of pornography on sexual scripts and hooking up among emerging adults in college.

    PubMed

    Braithwaite, Scott R; Coulson, Gwen; Keddington, Krista; Fincham, Frank D

    2015-01-01

    The explosive growth in access to the Internet has led to a commensurate increase in the availability, anonymity, and affordability of pornography. An emerging body of research has shown associations between pornography and certain behaviors and attitudes; yet, how pornography actually influences these outcomes has not been documented. In two studies (Study 1 N = 969; Study 2 N = 992) we examined the hypothesis that pornography influences potentially risky sexual behavior (hooking up) among emerging adults via sexual scripts. Our results demonstrate that more frequent viewing of pornography is associated with a higher incidence of hooking up and a higher number of unique hook up partners. We replicated these effects both cross-sectionally and longitudinally while accounting for the stability of hook ups over the course of an academic semester. We also demonstrated that more frequent viewing of pornography is associated with having had more previous sexual partners of all types, more one occasion sexual partners ("one night stands"), and plans to have a higher number of sexual partners in the future. Finally, we provided evidence that more permissive sexual scripts mediated the association between more frequent pornography viewing and hooking up. We discuss these findings with an eye toward mitigating potential personal and public health risks among emerging adults.

  11. Elimination of "hook-effect" in two-site immunoradiometric assays by kinetic rate analysis.

    PubMed

    Hoffman, K L; Parsons, G H; Allerdt, L J; Brooks, J M; Miles, L E

    1984-09-01

    Two-site or sandwich immunoradiometric assays (IRMAs) offer theoretical advantages over competitive immunoassay systems for sensitivity, precision, and rapid incubation. The practical realization of these advantages has been limited by the phenomenon of the "high-dose hook effect," such that high concentrations of an analyte give similar responses to those of much lower concentrations. We have developed a kinetic rate monitoring IRMA system for use with the Kineti-Count 48TM, an automated kinetic radioassay analyzer, which eliminates "hook-effect" interference, thereby permitting optimal assay design for increasing sensitivity and reducing incubation time. Practical illustration of these concepts is demonstrated by a 10-min, automated, quantitative assay we developed for human choriogonadotropin. The assay can detect as little as 1.2 int. units/L and kinetically screens for the hook effect. Kinetic rate analysis of the two-site IRMA and potentially of nonisotopic counterparts permits improvements in the speed and reliability of these immunoassays.

  12. Crafting the microworld: how Robert Hooke constructed knowledge about small things

    PubMed Central

    Lawson, Ian

    2016-01-01

    This paper investigates the way in which Robert Hooke constructed his microscopical observations. His Micrographia is justifiably famous for its detailed engravings, which communicated Hooke's observations of tiny nature to his readers, but less attention has been paid to how he went about making the observations themselves. In this paper I explore the relationship between the materiality of his instrument and the epistemic images he produced. Behind the pictures lies an array of hidden materials, and the craft knowledge it took to manipulate them. By investigating the often counter-theoretical and conflicting practices of his ingenious microscope use, I demonstrate the way in which Hooke crafted the microworld for his readers, giving insight into how early modern microscopy was understood by its practitioners and audience. PMID:27017680

  13. The discovery of microorganisms by Robert Hooke and Antoni Van Leeuwenhoek, fellows of the Royal Society.

    PubMed

    Gest, Howard

    2004-05-01

    The existence of microscopic organisms was discovered during the period 1665-83 by two Fellows of The Royal Society, Robert Hooke and Antoni van Leeuwenhoek. In Micrographia (1665), Hooke presented the first published depiction of a microganism, the microfungus Mucor. Later, Leeuwenhoek observed and described microscopic protozoa and bacteria. These important revelations were made possible by the ingenuity of Hooke and Leeuwenhoek in fabricating and using simple microscopes that magnified objects from about 25-fold to 250-fold. After a lapse of more than 150 years, microscopy became the backbone of our understanding of the roles of microbes in the causation of infectious diseases and the recycling of chemical elements in the biosphere.

  14. Toward a more complete understanding of reactions to hooking up among college women.

    PubMed

    Owen, Jesse; Quirk, Kelley; Fincham, Frank

    2014-01-01

    Hooking up, a relatively common behavior among young adults, refers to a casual sexual encounter, ranging from kissing to sexual intercourse, without an expectation of ongoing physical encounters or relational commitment. Reactions to hooking up have examined psychosocial outcomes as a proxy for specific reactions. The present study examined the reactions of 190 college women, with a specific focus on the effect of hooking up on their social/peer network, their sexual/romantic sense of self, and their academic performance. Results demonstrated large positive effects for sexual/romantic reactions and social/academic engagement reactions in comparison with negative personal reactions. In addition, higher ratings of anxious attachment, loneliness, and relational/intimacy sex motives were related to less positive reactions, highlighting the importance of attachment and motivations behind hookup experiences. Implications for educational practice and future research are offered.

  15. Application of optical tweezers and excimer laser to study protoplast fusion

    NASA Astrophysics Data System (ADS)

    Kantawang, Titirat; Samipak, Sompid; Limtrakul, Jumras; Chattham, Nattaporn

    2015-07-01

    Protoplast fusion is a physical phenomenon that two protoplasts come in contact and fuse together. Doing so, it is possible to combine specific genes from one protoplast to another during fusion such as drought resistance and disease resistance. There are a few possible methods to induce protoplast fusion, for example, electrofusion and chemical fusion. In this study, chemical fusion was performed with laser applied as an external force to enhance rate of fusion and observed under a microscope. Optical tweezers (1064 nm with 100X objective N.A. 1.3) and excimer laser (308 nm LMU-40X-UVB objective) were set with a Nikon Ti-U inverted microscope. Samples were prepared by soaking in hypertonic solution in order to induce cell plasmolysis. Elodea Canadensis and Allium cepa plasmolysed leaves were cut and observed under microscope. Concentration of solution was varied to induce difference turgor pressures on protoplasts pushing at cell wall. Free protoplasts in solution were trapped by optical tweezers to study the effect of Polyethylene glycol (PEG) solution. PEG was diluted by Ca+ solution during the process to induced protoplast cell contact and fusion. Possibility of protoplast fusion by excimer laser was investigated and found possible. Here we report a novel tool for plant cell fusion using excimer laser. Plant growth after cell fusion is currently conducted.

  16. Counter-propagating dual-trap optical tweezers based on linear momentum conservation

    SciTech Connect

    Ribezzi-Crivellari, M.; Huguet, J. M.; Ritort, F.

    2013-04-15

    We present a dual-trap optical tweezers setup which directly measures forces using linear momentum conservation. The setup uses a counter-propagating geometry, which allows momentum measurement on each beam separately. The experimental advantages of this setup include low drift due to all-optical manipulation, and a robust calibration (independent of the features of the trapped object or buffer medium) due to the force measurement method. Although this design does not attain the high-resolution of some co-propagating setups, we show that it can be used to perform different single molecule measurements: fluctuation-based molecular stiffness characterization at different forces and hopping experiments on molecular hairpins. Remarkably, in our setup it is possible to manipulate very short tethers (such as molecular hairpins with short handles) down to the limit where beads are almost in contact. The setup is used to illustrate a novel method for measuring the stiffness of optical traps and tethers on the basis of equilibrium force fluctuations, i.e., without the need of measuring the force vs molecular extension curve. This method is of general interest for dual trap optical tweezers setups and can be extended to setups which do not directly measure forces.

  17. Measuring integrated cellular mechanical stress response at focal adhesions by optical tweezers

    NASA Astrophysics Data System (ADS)

    Bordeleau, François; Bessard, Judicael; Marceau, Normand; Sheng, Yunlong

    2011-09-01

    The ability of cells to sustain mechanical stress is largely modulated by the cytoskeleton. We present a new application of optical tweezers to study cell's mechanical properties. We trap a fibronectin-coated bead attached to an adherent H4II-EC3 rat hepatoma cell in order to apply the force to the cell surface membrane. The bead position corresponding to the cell's local mechanical response at focal adhesions is measured with a quadrant detector. We assessed the cell response by tracking the evolution of the equilibrium force for 40 cells selected at random and selected a temporal window to assess the cell initial force expression at focal adhesions. The mean value of the force within this time window over 40 randomly selected bead/cell bounds was 52.3 pN. Then, we assessed the responses of the cells with modulation of the cytoskeletons, namely the ubiquitous actin-microfilaments and microtubules, plus the differentiation-dependent keratin intermediate filaments. Notably, a destabilization of the first two networks led to around 50 and 30% reductions in the mean equilibrium forces, respectively, relative to untreated cells, whereas a loss of the third one yielded a 25% increase. The differences in the forces from untreated and treated cells are resolved by the optical tweezers experiment.

  18. A combined double-tweezers and wavelength-tunable laser nanosurgery microscope

    NASA Astrophysics Data System (ADS)

    Zhu, Qingyuan; Parsa, Shahab; Shi, Linda Z.; Harsono, Marcellinus; Wakida, Nicole M.; Berns, Michael W.

    2009-08-01

    In two previous studies we have conducted combined laser subcellular microsurgery and optical trapping on chromosomes in living cells1, 2. In the latter study we used two separate microscopes, one for the trap and one for the laser scissors, thus requiring that we move the cell specimen between microscopes and relocate the irradiated cells. In the former paper we combined the 1064 nm laser trap and the 532 nm laser scissors into one microscope. However, in neither study did we have multiple traps allowing for more flexibility in application of the trapping force. In the present paper we describe a combined laser scissors and tweezers microscope that (1) has two trapping beams (both moveable via rapid scanning mirrors (FSM- 300, Newport Corp.), (2) uses a short pulsed tunable 200 fs 710-990 nm Ti:Sapphire laser for laser microsurgery, and (3) also has the option to use a 337 nm 4 ns UV laser for subcellular surgery. The two laser tweezers and either of the laser ablation beams can be used in a cell surgery experiment. The system is integrated into the robotic-controlled RoboLase system3. Experiments on mitotic chromosomes of rat kangaroo PTK2 cells are described.

  19. Optical tweezers and cell biomechanics in macro- and nano-scale

    NASA Astrophysics Data System (ADS)

    Serafetinides, Alexander A.; Makropoulou, Mersini; Spyratou, Ellas

    2013-03-01

    The mechanical properties of cells, as well as their dysfunction, have been implicated in many aspects of human physiology and patho-physiology. Hence, new biophysical techniques, as optical tweezers, are of great importance for biomechanical measurements in both cells and cell simulators (e.g. liposomes). Liposomes are used, among other applications, as drug delivery nanosystems in cancer therapy. In this work, experimental measurements of the optical forces exerted by line optical tweezers on trapped cells (erythrocytes) and liposomes, using the dielectrophoresis method for calibration, are presented. Folding and elongation of trapped red blood cells was observed, in the direction of the electric field of incident beam, while, upon removal of the optical trap, the red blood cells were observed to unfold to their original biconcave shape. By measuring the folding and unfolding times, membrane elasticity properties such as bending modulus were estimated. Shear and bending modulus of liposomes were also estimated by measuring the liposome deformations, induced by optical forces along the beam long axis. The optical force is quasi-linearly increased with the increase of liposome diameter. In the elasticity regime, when the laser was turned off, the liposome acquired gradually its initial shape without any hysteresis.

  20. Analysis of cell mechanics in single vinculin-deficient cells using a magnetic tweezer

    NASA Technical Reports Server (NTRS)

    Alenghat, F. J.; Fabry, B.; Tsai, K. Y.; Goldmann, W. H.; Ingber, D. E.

    2000-01-01

    A magnetic tweezer was constructed to apply controlled tensional forces (10 pN to greater than 1 nN) to transmembrane receptors via bound ligand-coated microbeadswhile optically measuring lateral bead displacements within individual cells. Use of this system with wild-type F9 embryonic carcinoma cells and cells from a vinculin knockout mouse F9 Vin (-/-) revealed much larger differences in the stiffness of the transmembrane integrin linkages to the cytoskeleton than previously reported using related techniques that measured average mechanical properties of large cell populations. The mechanical properties measured varied widely among cells, exhibiting an approximately log-normal distribution. The median lateral bead displacement was 2-fold larger in F9 Vin (-/-) cells compared to wild-type cells whereas the arithmetic mean displacement only increased by 37%. We conclude that vinculin serves a greater mechanical role in cells than previously reported and that this magnetic tweezer device may be useful for probing the molecular basis of cell mechanics within single cells. Copyright 2000 Academic Press.

  1. Binding mechanism of PicoGreen to DNA characterized by magnetic tweezers and fluorescence spectroscopy.

    PubMed

    Wang, Ying; Schellenberg, Helene; Walhorn, Volker; Toensing, Katja; Anselmetti, Dario

    2017-03-01

    Fluorescent dyes are broadly used in many biotechnological applications to detect and visualize DNA molecules. However, their binding to DNA alters the structural and nanomechanical properties of DNA and, thus, interferes with associated biological processes. In this work we employed magnetic tweezers and fluorescence spectroscopy to investigate the binding of PicoGreen to DNA at room temperature in a concentration-dependent manner. PicoGreen is an ultrasensitive quinolinium nucleic acid stain exhibiting hardly any background signal from unbound dye molecules. By means of stretching and overwinding single, torsionally constrained, nick-free double-stranded DNA molecules, we acquired force-extension and supercoiling curves which allow quantifying DNA contour length, persistence length and other thermodynamical binding parameters, respectively. The results of our magnetic tweezers single-molecule binding study were well supported through analyzing the fluorescent spectra of stained DNA. On the basis of our work, we could identify a concentration-dependent bimodal binding behavior, where, apparently, PicoGreen associates to DNA as an intercalator and minor-groove binder simultaneously.

  2. In situ microparticle analysis of marine phytoplankton cells with infrared laser-based optical tweezers

    NASA Astrophysics Data System (ADS)

    Sonek, G. J.; Liu, Y.; Iturriaga, R. H.

    1995-11-01

    We describe the application of infrared optical tweezers to the in situ microparticle analysis of marine phytoplankton cells. A Nd:YAG laser (lambda=3D 1064 nm) trap is used to confine and manipulate single Nannochloris and Synechococcus cells in an enriched seawater medium while spectral fluorescence and Lorenz-Mie backscatter signals are simultaneously acquired under a variety of excitation and trapping conditions. Variations in the measured fluorescence intensities of chlorophyll a (Chl a) and phycoerythrin pigments in phytoplankton cells are observed. These variations are related, in part, to basic intrasample variability, but they also indicate that increasing ultraviolet-exposure time and infrared trapping power may have short-term effects on cellular physiology that are related to Chl a photobleaching and laser-induced heating, respectively. The use of optical tweezers to study the factors that affect marine cell physiology and the processes of absorption, scattering, and attenuation by individual cells, organisms, and particulate matter that contribute to optical closure on a microscopic scale are also described. (c)1995 Optical Society of America

  3. Optical tweezers and non-ratiometric fluorescent-dye-based studies of respiration in sperm mitochondria

    NASA Astrophysics Data System (ADS)

    Chen, Timothy; Shi, Linda Z.; Zhu, Qingyuan; Chandsawangbhuwana, Charlie; Berns, Michael W.

    2011-04-01

    The purpose of this study is to investigate how the mitochondrial membrane potential affects sperm motility using laser tweezers and a non-ratiometric fluorescent probe, DiOC6(3). A 1064 nm Nd:YVO4 continuous wave laser was used to trap motile sperm at a power of 450 mW in the trap spot. Using customized tracking software, the curvilinear velocity (VCL) and the escape force from the laser tweezers were measured. Human (Homo sapiens), dog (Canis lupis familiaris) and drill (Mandrillus leucophaeus) sperm were treated with DiOC6(3) to measure the membrane potential in the mitochondria-rich sperm midpieces. Sperm from all three species exhibited an increase in fluorescence when treated with the DiOC6(3). When a cyanide inhibitor (CCCP) of aerobic respiration was applied, sperm of all three species exhibited a reduction in fluorescence to pre-dye levels. With respect to VCL and escape force, the CCCP had no effect on dog or human sperm, suggesting a major reliance upon anaerobic respiration (glycolysis) for ATP in these two species. Based on the preliminary study on drill sperm, CCCP caused a drop in the VCL, suggesting potential reliance on both glycolysis and aerobic respiration for motility. The results demonstrate that optical trapping in combination with DiOC6(3) is an effective way to study sperm motility and energetics.

  4. Laser scanning confocal microscopy and laser tweezers based experiments to understand dentine-bacteria interactions

    NASA Astrophysics Data System (ADS)

    Peng, Sum Chee; Mohanty, Samarendra; Gupta, P. K.; Kishen, Anil

    2007-02-01

    Failure of endodontic treatment is commonly due to Enterococcal infection. In this study influence of chemical treatments of type-I collagen membrane by chemical agents commonly used in endodontic treatment on Enterococcus faecalis cell adherence was evaluated. In order to determine the change in number of adhering bacteria after chemical treatment, confocal laser scanning microscopy was used. For this, overnight culture of E faecalis in All Culture broth was applied to chemically treated type-I collagen membrane. It was found that Ca(OH) II treated groups had statistically significant (p value=0.05) increase in population of bacteria adherence. The change in adhesion force between bacteria and collagen was determined by using optical tweezers (1064 nm). For this experiment, Type-I collagen membrane was soaked for 5 mins in a media that contained 50% all culture media and 50% saturated Ca(OH) II . The membrane was spread on the coverslip, on which diluted bacterial suspension was added. The force of laser tweezers on the bacteria was estimated at different trap power levels using viscous drag method and trapping stiffness was calculated using Equipartition theorem method. Presence of Ca(OH) II was found to increase the cell-substrate adherence force from 0.38pN to >2.1pN. Together, these experiments show that it was highly probable that the increase in adherence to collagen was due to a stronger adhesion in the presence of Ca (OH) II.

  5. Chemotaxis study using optical tweezers to observe the strength and directionality of forces of Leishmania amazonensis

    NASA Astrophysics Data System (ADS)

    Pozzo, Liliana d. Y.; Fontes, Adriana; de Thomaz, André A.; Barbosa, Luiz C.; Ayres, Diana C.; Giorgio, Selma; Cesar, Carlos L.

    2006-08-01

    The displacements of a dielectric microspheres trapped by an optical tweezers (OT) can be used as a force transducer for mechanical measurements in life sciences. This system can measure forces on the 50 femto Newtons to 200 pico Newtons range, of the same order of magnitude of a typical forces induced by flagellar motion. The process in which living microorganisms search for food and run away from poison chemicals is known is chemotaxy. Optical tweezers can be used to obtain a better understanding of chemotaxy by observing the force response of the microorganism when placed in a gradient of attractors and or repelling chemicals. This report shows such observations for the protozoa Leishmania amazomenzis, responsible for the leishmaniasis, a serious tropical disease. We used a quadrant detector to monitor the movement of the protozoa for different chemicals gradient. This way we have been able to observe both the force strength and its directionality. The characterization of the chemotaxis of these parasites can help to understand the infection mechanics and improve the diagnosis and the treatments employed for this disease.

  6. Counter-propagating dual-trap optical tweezers based on linear momentum conservation.

    PubMed

    Ribezzi-Crivellari, M; Huguet, J M; Ritort, F

    2013-04-01

    We present a dual-trap optical tweezers setup which directly measures forces using linear momentum conservation. The setup uses a counter-propagating geometry, which allows momentum measurement on each beam separately. The experimental advantages of this setup include low drift due to all-optical manipulation, and a robust calibration (independent of the features of the trapped object or buffer medium) due to the force measurement method. Although this design does not attain the high-resolution of some co-propagating setups, we show that it can be used to perform different single molecule measurements: fluctuation-based molecular stiffness characterization at different forces and hopping experiments on molecular hairpins. Remarkably, in our setup it is possible to manipulate very short tethers (such as molecular hairpins with short handles) down to the limit where beads are almost in contact. The setup is used to illustrate a novel method for measuring the stiffness of optical traps and tethers on the basis of equilibrium force fluctuations, i.e., without the need of measuring the force vs molecular extension curve. This method is of general interest for dual trap optical tweezers setups and can be extended to setups which do not directly measure forces.

  7. Application of laser tweezers Raman spectroscopy techniques to the monitoring of single cell response to stimuli

    NASA Astrophysics Data System (ADS)

    Chan, James W.; Liu, Rui; Matthews, Dennis L.

    2012-06-01

    Laser tweezers Raman spectroscopy (LTRS) combines optical trapping with micro-Raman spectroscopy to enable label-free biochemical analysis of individual cells and small biological particles in suspension. The integration of the two technologies greatly simplifies the sample preparation and handling of suspension cells for spectroscopic analysis in physiologically meaningful conditions. In our group, LTRS has been used to study the effects of external perturbations, both chemical and mechanical, on the biochemistry of the cell. Single cell dynamics can be studied by performing longitudinal studies to continuously monitor the response of the cell as it interacts with its environment. The ability to carry out these measurements in-vitro makes LTRS an attractive tool for many biomedical applications. Here, we discuss the use of LTRS to study the response of cancer cells to chemotherapeutics and bacteria cells to antibiotics and show that the life cycle and apoptosis of the cells can be detected. These results show the promise of LTRS for drug discovery/screening, antibiotic susceptibility testing, and chemotherapy response monitoring applications. In separate experiments, we study the response of red blood cells to the mechanical forces imposed on the cell by the optical tweezers. A laser power dependent deoxygenation of the red blood cell in the single beam trap is reported. Normal, sickle cell, and fetal red blood cells have a different behavior that enables the discrimination of the cell types based on this mechanochemical response. These results show the potential utility of LTRS for diagnosing and studying red blood cell diseases.

  8. Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

    SciTech Connect

    Ott, Dino; Oddershede, Lene B.; Reihani, S. Nader S.

    2014-05-15

    In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Here we present a simple and easy-to-implement method to efficiently eliminate crosstalk. The method is based on spatial filtering by simply inserting a pinhole at the correct position and is highly compatible with standard back focal plane photodiode based detection of position and force. Our spatial filtering method reduces crosstalk up to five times better than polarization filtering alone. The effectiveness is dependent on pinhole size and distance between the traps and is here quantified experimentally and reproduced by theoretical modeling. The method here proposed will improve the accuracy of force-distance measurements, e.g., of single molecules, performed by dual-beam optical traps and hence give much more scientific value for the experimental efforts.

  9. A modular assembling platform for manufacturing of microsystems by optical tweezers

    NASA Astrophysics Data System (ADS)

    Ksouri, Sarah Isabelle; Aumann, Andreas; Ghadiri, Reza; Prüfer, Michael; Baer, Sebastian; Ostendorf, Andreas

    2013-09-01

    Due to the increased complexity in terms of materials and geometries for microsystems new assembling techniques are required. Assembling techniques from the semiconductor industry are often very specific and cannot fulfill all specifications in more complex microsystems. Therefore, holographic optical tweezers are applied to manipulate structures in micrometer range with highest flexibility and precision. As is well known non-spherical assemblies can be trapped and controlled by laser light and assembled with an additional light modulator application, where the incident laser beam is rearranged into flexible light patterns in order to generate multiple spots. The complementary building blocks are generated by a two-photon-polymerization process. The possibilities of manufacturing arbitrary microstructures and the potential of optical tweezers lead to the idea of combining manufacturing techniques with manipulation processes to "microrobotic" processes. This work presents the manipulation of generated complex microstructures with optical tools as well as a storage solution for 2PP assemblies. A sample holder has been developed for the manual feeding of 2PP building blocks. Furthermore, a modular assembling platform has been constructed for an `all-in-one' 2PP manufacturing process as a dedicated storage system. The long-term objective is the automation process of feeding and storage of several different 2PP micro-assemblies to realize an automated assembly process.

  10. A study of red blood cell deformability in diabetic retinopathy using optical tweezers

    NASA Astrophysics Data System (ADS)

    Smart, Thomas J.; Richards, Christopher J.; Bhatnagar, Rhythm; Pavesio, Carlos; Agrawal, Rupesh; Jones, Philip H.

    2015-08-01

    Diabetic retinopathy (DR) is a microvascular complication of diabetes mellitus (DM) in which high blood sugar levels cause swelling, leaking and occlusions in the blood vessels of the retina, often resulting in a loss of sight. The microvascular system requires red blood cells (RBCs) to undergo significant cellular deformation in order to pass through vessels whose diameters are significantly smaller than their own. There is evidence to suggest that DM impairs the deformability of RBCs, and this loss of deformability has been associated with diabetic kidney disease (or nephropathy) - another microvascular complication of DM. However, it remains unclear whether reduced deformability of RBCs correlates with the presence of DR. Here we present an investigation into the deformability of RBCs in patients with diabetic retinopathy using optical tweezers. To extract a value for the deformability of RBCs we use a dual-trap optical tweezers set-up to stretch individual RBCs. RBCs are trapped directly (i.e. without micro-bead handles), so rotate to assume a `side-on' orientation. Video microscopy is used to record the deformation events, and shape analysis software is used to determine parameters such as initial and maximum RBC length, allowing us to calculate the deformability for each RBC. A small decrease in deformability of diabetes cells subject to this stretching protocol is observed when compared to control cells. We also report on initial results on three dimensional imaging of individual RBCs using defocussing microscopy.

  11. Optical Tweezers as a New Biomedical Tool to Measure Zeta Potential of Stored Red Blood Cells

    PubMed Central

    Silva, Carlos A. L.; Fernandes, Heloise P.; Filho, Milton M.; Lucena, Sheyla C.; Costa, Ana Maria D. N.; Cesar, Carlos L.; Barjas-Castro, Maria L.; Santos, Beate S.; Fontes, Adriana

    2012-01-01

    During storage, red blood cells (RBCs) for transfusion purposes suffer progressive deterioration. Sialylated glycoproteins of the RBC membrane are responsible for a negatively charged surface which creates a repulsive electrical zeta potential. These charges help prevent the interaction between RBCs and other cells, and especially among each RBCs. Reports in the literature have stated that RBCs sialylated glycoproteins can be sensitive to enzymes released by leukocyte degranulation. Thus, the aim of this study was, by using an optical tweezers as a biomedical tool, to measure the zeta potential in standard RBCs units and in leukocyte reduced RBC units (collected in CPD-SAGM) during storage. Optical tweezers is a sensitive tool that uses light for measuring cell biophysical properties which are important for clinical and research purposes. This is the first study to analyze RBCs membrane charges during storage. In addition, we herein also measured the elasticity of RBCs also collected in CPD-SAGM. In conclusion, the zeta potential decreased 42% and cells were 134% less deformable at the end of storage. The zeta potential from leukodepleted units had a similar profile when compared to units stored without leukoreduction, indicating that leukocyte lyses were not responsible for the zeta potential decay. Flow cytometry measurements of reactive oxygen species suggested that this decay is due to membrane oxidative damages. These results show that measurements of zeta potentials provide new insights about RBCs storage lesion for transfusion purposes. PMID:22363729

  12. Measurement of particle motion in optical tweezers embedded in a Sagnac interferometer.

    PubMed

    Galinskiy, Ivan; Isaksson, Oscar; Salgado, Israel Rebolledo; Hautefeuille, Mathieu; Mehlig, Bernhard; Hanstorp, Dag

    2015-10-19

    We have constructed a counterpropagating optical tweezers setup embedded in a Sagnac interferometer in order to increase the sensitivity of position tracking for particles in the geometrical optics regime. Enhanced position determination using a Sagnac interferometer has previously been described theoretically by Taylor et al. [Journal of Optics 13, 044014 (2011)] for Rayleigh-regime particles trapped in an antinode of a standing wave. We have extended their theory to a case of arbitrarily-sized particles trapped with orthogonally-polarized counter-propagating beams. The working distance of the setup was sufficiently long to optically induce particle oscillations orthogonally to the axis of the tweezers with an auxiliary laser beam. Using these oscillations as a reference, we have experimentally shown that Sagnac-enhanced back focal plane interferometry is capable of providing an improvement of more than 5 times in the signal-to-background ratio, corresponding to a more than 30-fold improvement of the signal-to-noise ratio. The experimental results obtained are consistent with our theoretical predictions. In the experimental setup, we used a method of optical levitator-assisted liquid droplet delivery in air based on commercial inkjet technology, with a novel method to precisely control the size of droplets.

  13. Optical Tweezers Studies on Notch: Single-molecule Interaction Strength is Independent of Ligand Endocytosis

    PubMed Central

    Shergill, Bhupinder; Meloty-Kapella, Laurence; Musse, Abdiwahab A.; Weinmaster, Gerry; Botvinick, Elliot

    2012-01-01

    SUMMARY Notch signaling controls diverse cellular processes critical to development and disease. Cell surface ligands bind Notch on neighboring cells yet require endocytosis to activate signaling. The role ligand endocytosis plays in Notch activation has not been established. Here we integrate optical tweezers with cell biological and biochemical methods to test the prevailing model that ligand endocytosis facilitates recycling to enhance ligand interactions with Notch necessary to trigger signaling. Specifically, single-molecule measurements indicate that interference of ligand endocytosis and/or recycling does not alter the force required to rupture bonds formed between cells expressing the Notch ligand Delta-like1 (Dll1) and laser-trapped Notch1-beads. Together, our analyses eliminate roles for ligand endocytosis and recycling in Dll1-Notch1 interactions, and indicate that recycling indirectly affects signaling by regulating the accumulation of cell-surface ligand. Importantly, our study demonstrates the utility of optical tweezers to test a role for ligand endocytosis in generating cell-mediated mechanical force. PMID:22658935

  14. A novel single fiber optical tweezers based on light-induced thermal effect

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Liu, Zhihai; Liang, Peibo; Zhang, Yaxun; Zhao, Enming; Yang, Jun; Yuan, Libo

    2015-07-01

    We present and demonstrate a novel single fiber optical tweezers which can trap and launch (clean) a target polystyrene (PS) microsphere (diameter~10μm) with independent control by using two wavelengths beams: 980nm and 1480nm. We employ 980nm laser beam to trap the target PS microsphere by molding the fiber tip into a special tapered-shape; and we employ 1480nm laser beam to launch the trapped PS microsphere with a certain velocity by using the thermophoresis force generated from the thermal effect due to the high absorption of the 1480nm laser beams in water. When the launching force is smaller than the trapping force, the PS microsphere will be trapped near the fiber tip, and the launching force will blow away other PS microspheres in the workspace realizing the cleaning function; When the launching force is larger than the trapping force, the trapped PS microsphere will be launched away from the fiber tip with a certain velocity and towards a certain direction, realizing the launching function. This PS microsphere launching and cleaning functions expanded new features of single fiber optical tweezers, providing for the possibility of more practical applications in the micro manipulation research fields.

  15. Understanding local forces in electrophoretic ink systems: utilizing optical tweezers to explore electrophoretic display devices

    NASA Astrophysics Data System (ADS)

    Wei, David L.; Dickinson, Mark R.; Smith, N.; Gleeson, Helen F.

    2016-09-01

    Optical tweezers can be used as a valuable tool to characterize electrophoretic display (EPD) systems. EPDs are ubiquitous with e-readers and are becoming a commonplace technology where reflective, low-power displays are required; yet the physics of some features crucial to their operation remains poorly defined. We utilize optical tweezers as a tool to understand the motion of charged ink particles within the devices and show that the response of optically trapped electrophoretic particles can be used to characterize electric fields within these devices. This technique for mapping the force can be compared to simulations of the electric field in our devices, thus demonstrating that the electric field itself is the sole governor of the particle motion in an individual-particle regime. By studying the individual-particle response to the electric field, we can then begin to characterize particle motion in `real' systems with many particles. Combining optical tweezing with particle tracking techniques, we can investigate deviations in many particle systems from the single-particle case.

  16. Design of hybrid optical tweezers system for controlled three-dimensional micromanipulation

    NASA Astrophysics Data System (ADS)

    Tanaka, Yoshio; Tsutsui, Shogo; Kitajima, Hiroyuki

    2013-04-01

    Three-dimensional (3D) micro/nano-manipulation using optical tweezers is a significant technique for various scientific fields ranging from biology to nanotechnology. For the dynamic handling of multiple/individual micro-objects in a true 3D working space, we present an improved hybrid optical tweezers system consisting of two multibeam techniques. These two techniques include the generalized phase contrast method with a spatial light modulator and the time-shared scanning method with a two-axis steering mirror and an electrically focus-tunable lens. Unlike our previously reported system that could only handle micro-objects in a two and half dimensional working space, the present system has high versatility for controlled manipulation of multiple micro-objects in a true 3D working space. The controlled rotation of five beads forming a pentagon, that of four beads forming a tetrahedron about arbitrary axes, and the fully automated assembly and subsequent 3D translation of micro-bead arrays are successfully demonstrated as part of the 3D manipulation experiment.

  17. Natural user interface as a supplement of the holographic Raman tweezers

    NASA Astrophysics Data System (ADS)

    Tomori, Zoltan; Kanka, Jan; Kesa, Peter; Jakl, Petr; Sery, Mojmir; Bernatova, Silvie; Antalik, Marian; Zemánek, Pavel

    2014-09-01

    Holographic Raman tweezers (HRT) manipulates with microobjects by controlling the positions of multiple optical traps via the mouse or joystick. Several attempts have appeared recently to exploit touch tablets, 2D cameras or Kinect game console instead. We proposed a multimodal "Natural User Interface" (NUI) approach integrating hands tracking, gestures recognition, eye tracking and speech recognition. For this purpose we exploited "Leap Motion" and "MyGaze" low-cost sensors and a simple speech recognition program "Tazti". We developed own NUI software which processes signals from the sensors and sends the control commands to HRT which subsequently controls the positions of trapping beams, micropositioning stage and the acquisition system of Raman spectra. System allows various modes of operation proper for specific tasks. Virtual tools (called "pin" and "tweezers") serving for the manipulation with particles are displayed on the transparent "overlay" window above the live camera image. Eye tracker identifies the position of the observed particle and uses it for the autofocus. Laser trap manipulation navigated by the dominant hand can be combined with the gestures recognition of the secondary hand. Speech commands recognition is useful if both hands are busy. Proposed methods make manual control of HRT more efficient and they are also a good platform for its future semi-automated and fully automated work.

  18. Simultaneous Multiple Preoperative Localizations of Small Pulmonary Lesions Using a Short Hook Wire and Suture System

    SciTech Connect

    Iguchi, Toshihiro Hiraki, Takao Gobara, Hideo Fujiwara, Hiroyasu Matsui, Yusuke; Sugimoto, Seiichiro Toyooka, Shinichi Oto, Takahiro Miyoshi, Shinichiro; Kanazawa, Susumu

    2015-08-15

    PurposeThe aim of the study was to retrospectively evaluate simultaneous multiple hook wire placement outcomes before video-assisted thoracoscopic surgery (VATS).Materials and MethodsThirty-eight procedures were performed on 35 patients (13 men and 22 women; mean age, 59.9 years) with 80 lung lesions (mean diameter 7.9 mm) who underwent simultaneous multiple hook wire placements for preoperative localizations. The primary endpoints were technical success, complications, procedure duration, and VATS outcome; secondary endpoints included comparisons between technical success rates, complication rates, and procedure durations of the 238 single-placement procedures performed. Complications were also evaluated.ResultsIn 35 procedures including 74 lesions, multiple hook wire placements were technically successful; in the remaining three procedures, the second target placement was aborted because of massive pneumothorax after the first placement. Although complications occurred in 34 procedures, no grade 3 or above adverse event was observed. The mean procedure duration was 36.4 ± 11.8 min. Three hook wires dislodged during patient transport to the surgical suite. Seventy-four successfully marked lesions were resected. Six lesions without hook wires were successfully resected after detection by palpation with an additional mini-thoracotomy or using subtle pleural changes as a guide. The complication rates and procedure durations of multiple-placement procedures were significantly higher (P = 0.04) and longer (P < 0.001) than those in the single-placement group, respectively, while the technical success rate was not significantly different (P = 0.051).ConclusionsSimultaneous multiple hook wire placements before VATS were clinically feasible, but increased the complication rate and lengthened the procedure time.

  19. 75 FR 7403 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod by Catcher/Processors Using Hook...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-19

    ... Economic Zone Off Alaska; Pacific Cod by Catcher/Processors Using Hook-and-Line Gear in the Bering Sea and... directed fishing for Pacific cod by catcher/processors using hook-and-line gear in the Bering Sea and... allowance of the 2010 Pacific cod total allowable catch (TAC) allocated to catcher/processors using...

  20. The hooked element in the pes of turtles (Testudines): a global approach to exploring primary and secondary homology.

    PubMed

    Joyce, Walter G; Werneburg, Ingmar; Lyson, Tyler R

    2013-11-01

    The hooked element in the pes of turtles was historically identified by most palaeontologists and embryologists as a modified fifth metatarsal, and often used as evidence to unite turtles with other reptiles with a hooked element. Some recent embryological studies, however, revealed that this element might represent an enlarged fifth distal tarsal. We herein provide extensive new myological and developmental observations on the hooked element of turtles, and re-evaluate its primary and secondary homology using all available lines of evidence. Digital count and timing of development are uninformative. However, extensive myological, embryological and topological data are consistent with the hypothesis that the hooked element of turtles represents a fusion of the fifth distal tarsal with the fifth metatarsal, but that the fifth distal tarsal dominates the hooked element in pleurodiran turtles, whereas the fifth metatarsal dominates the hooked element of cryptodiran turtles. The term 'ansulate bone' is proposed to refer to hooked elements that result from the fusion of these two bones. The available phylogenetic and fossil data are currently insufficient to clarify the secondary homology of hooked elements within Reptilia.

  1. 33 CFR 334.102 - Sandy Hook Bay, Naval Weapons Station EARLE, Piers and Terminal Channel, restricted area...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Sandy Hook Bay, Naval Weapons... DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.102 Sandy Hook Bay, Naval Weapons Station EARLE, Piers..., shall be enforced by the Commanding Officer, Naval Weapons Station Earle, and/or other persons...

  2. 33 CFR 334.102 - Sandy Hook Bay, Naval Weapons Station EARLE, Piers and Terminal Channel, restricted area...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Sandy Hook Bay, Naval Weapons... DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.102 Sandy Hook Bay, Naval Weapons Station EARLE, Piers..., shall be enforced by the Commanding Officer, Naval Weapons Station Earle, and/or other persons...

  3. 33 CFR 334.102 - Sandy Hook Bay, Naval Weapons Station EARLE, Piers and Terminal Channel, restricted area...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Sandy Hook Bay, Naval Weapons... DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.102 Sandy Hook Bay, Naval Weapons Station EARLE, Piers..., shall be enforced by the Commanding Officer, Naval Weapons Station Earle, and/or other persons...

  4. 33 CFR 334.102 - Sandy Hook Bay, Naval Weapons Station EARLE, Piers and Terminal Channel, restricted area...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Sandy Hook Bay, Naval Weapons... DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.102 Sandy Hook Bay, Naval Weapons Station EARLE, Piers..., shall be enforced by the Commanding Officer, Naval Weapons Station Earle, and/or other persons...

  5. 33 CFR 334.102 - Sandy Hook Bay, Naval Weapons Station EARLE, Piers and Terminal Channel, restricted area...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Sandy Hook Bay, Naval Weapons... DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.102 Sandy Hook Bay, Naval Weapons Station EARLE, Piers..., shall be enforced by the Commanding Officer, Naval Weapons Station Earle, and/or other persons...

  6. Automation Hooks Architecture for Flexible Test Orchestration - Concept Development and Validation

    NASA Technical Reports Server (NTRS)

    Lansdowne, C. A.; Maclean, John R.; Winton, Chris; McCartney, Pat

    2011-01-01

    The Automation Hooks Architecture Trade Study for Flexible Test Orchestration sought a standardized data-driven alternative to conventional automated test programming interfaces. The study recommended composing the interface using multicast DNS (mDNS/SD) service discovery, Representational State Transfer (Restful) Web Services, and Automatic Test Markup Language (ATML). We describe additional efforts to rapidly mature the Automation Hooks Architecture candidate interface definition by validating it in a broad spectrum of applications. These activities have allowed us to further refine our concepts and provide observations directed toward objectives of economy, scalability, versatility, performance, severability, maintainability, scriptability and others.

  7. Anterior cruciate ligament rupture secondary to a 'heel hook': a dangerous martial arts technique.

    PubMed

    Baker, Joseph F; Devitt, Brian M; Moran, Ray

    2010-01-01

    The 'heel hook' is a type of knee lock used in some forms of martial arts to stress the knee and cause opponent to concede defeat. While the knee is in a flexed and valgus disposition, an internal rotation force is applied to the tibia. Reports are lacking on serious knee trauma as a result of this technique. We report the case of a 32-year-old Mixed Martial Arts exponent who sustained complete anterior cruciate ligament rupture and an medial collateral ligament injury from the use of a 'heel hook'.

  8. Purification and characterization of the flagellar hook-basal body complex of Bacillus subtilis.

    PubMed

    Kubori, T; Okumura, M; Kobayashi, N; Nakamura, D; Iwakura, M; Aizawa, S I

    1997-04-01

    The flagellar hook-basal body (HBB) complex of the Gram-positive bacterium Bacillus subtilis was purified and analysed by electron microscopy, gel electrophoresis, and amino acid sequencing of the major component proteins. The purified HBB complex consisted of the inner (M and S) rings, a rod and a hook. There were no outer (P and L) rings that are found in Gram-negative bacteria. The hook was 15 nm in thickness and 70 nm in length, which is thinner and longer than the hook of Salmonella typhimurium. The hook protein had an apparent molecular mass of 29 kDa, and its N-terminal sequence was identical to that of B. subtilis FIgG, which was previously reported as a rod protein. The sequence of the reported FIgG protein of B. subtilis is more closely related to that of FIgE (the hook protein) rather than FIgG (the rod protein) of S. typhimurium, in spite of the difference of the apparent molecular masses between the two hook proteins (29 kDa versus 42 kDa). The hook-basal body contained six major proteins (with apparent molecular masses of 82, 59, 35, 32, 29 and 20 kDa) and two minor proteins (23 kDa and 13 kDa), which consistently appeared from preparation to preparation. The N-terminus of each of these proteins was sequenced. Comparison with protein databases revealed the following polypeptide-gene correspondences: 82 kDa, fIiF; 59 kDa, fIgK; 35 kDa, orfF; 32 kDa, yqhF; 23 kDa, orf3 of the fIaA locus; 20 kDa, fIgB and fIgC; 13 kDa, not determined. The band at 20 kDa was a mixture of FIgB and FIgC, as revealed by two-dimensional gel analysis. Characteristic features of B. subtilis HBB are discussed in comparison with those of S. typhimiurium.

  9. Optical trapping of a spherically symmetric sphere in the ray-optics regime: a model for optical tweezers upon cells

    SciTech Connect

    Chang Yiren; Hsu Long; Chi Sien

    2006-06-01

    Since their invention in 1986, optical tweezers have become a popular manipulation and force measurement tool in cellular and molecular biology. However, until recently there has not been a sophisticated model for optical tweezers on trapping cells in the ray-optics regime. We present a model for optical tweezers to calculate the optical force upon a spherically symmetric multilayer sphere representing a common biological cell. A numerical simulation of this model shows that not only is the magnitude of the optical force upon a Chinese hamster ovary cell significantly three times smaller than that upon a polystyrene bead of the same size, but the distribution of the optical force upon a cell is also much different from that upon a uniform particle, and there is a 30% difference in the optical trapping stiffness of these two cases. Furthermore, under a small variant condition for the refractive indices of any adjacent layers of the sphere, this model provides a simple approximation to calculate the optical force and the stiffness of an optical tweezers system.

  10. Energy Landscape of Alginate-Epimerase Interactions Assessed by Optical Tweezers and Atomic Force Microscopy

    PubMed Central

    Håti, Armend Gazmeno; Aachmann, Finn Lillelund; Stokke, Bjørn Torger; Skjåk-Bræk, Gudmund; Sletmoen, Marit

    2015-01-01

    Mannuronan C-5 epimerases are a family of enzymes that catalyze epimerization of alginates at the polymer level. This group of enzymes thus enables the tailor-making of various alginate residue sequences to attain various functional properties, e.g. viscosity, gelation and ion binding. Here, the interactions between epimerases AlgE4 and AlgE6 and alginate substrates as well as epimerization products were determined. The interactions of the various epimerase–polysaccharide pairs were determined over an extended range of force loading rates by the combined use of optical tweezers and atomic force microscopy. When studying systems that in nature are not subjected to external forces the access to observations obtained at low loading rates, as provided by optical tweezers, is a great advantage since the low loading rate region for these systems reflect the properties of the rate limiting energy barrier. The AlgE epimerases have a modular structure comprising both A and R modules, and the role of each of these modules in the epimerization process were examined through studies of the A- module of AlgE6, AlgE6A. Dynamic strength spectra obtained through combination of atomic force microscopy and the optical tweezers revealed the existence of two energy barriers in the alginate-epimerase complexes, of which one was not revealed in previous AFM based studies of these complexes. Furthermore, based on these spectra estimates of the locations of energy transition states (xβ), lifetimes in the absence of external perturbation (τ0) and free energies (ΔG#) were determined for the different epimerase–alginate complexes. This is the first determination of ΔG# for these complexes. The values determined were up to 8 kBT for the outer barrier, and smaller values for the inner barriers. The size of the free energies determined are consistent with the interpretation that the enzyme and substrate are thus not tightly locked at all times but are able to relocate. Together with the

  11. Spirochete flagella hook protein self-catalyze a lysinoalanine covalent cross-link for motility

    PubMed Central

    Miller, Michael R.; Miller, Kelly A.; Bian, Jiang; James, Milinda E.; Zhang, Sheng; Lynch, Michael; Callery, Patrick S.; Hettick, Justin M.; Cockburn, Andrew; Liu, Jun; Li, Chunhao; Crane, Brian R.; Charon, Nyles W.

    2016-01-01

    Spirochetes are bacteria responsible for several serious diseases that include Lyme disease (Borrelia burgdorferi), syphilis (Treponema pallidum), leptospirosis (Leptospira interrogans), and contribute to periodontal diseases (Treponema denticola)1. These spirochetes employ an unusual form of flagella-based motility necessary for pathogenicity; indeed, spirochete flagella (periplasmic flagella, PFs) reside and rotate within the periplasmic space2–11. The universal joint or hook that links the rotary motor to the filament is composed of approximately 120–130 FlgE proteins, which in spirochetes form an unusually stable, high-molecular weight complex (HMWC)9,12–17. In other bacteria, the hook can be readily dissociated by treatments such as heat18. In contrast, spirochete hooks are resistant to these treatments, and several lines of evidence indicate that the HMWC is the consequence of covalent cross-linking12,13,17. Here we show that T. denticola FlgE self-catalyzes an interpeptide cross-linking reaction between conserved lysine and cysteine resulting in the formation of an unusual lysinoalanine adduct that polymerizes the hook subunits. Lysinoalanine cross-links are not needed for flagellar assembly, but they are required for cell motility, and hence infection. The self-catalytic nature of FlgE cross-linking has important implications for protein engineering, and its sensitivity to chemical inhibitors provides a new avenue for the development of antimicrobials targeting spirochetes. PMID:27670115

  12. 46 CFR 7.35 - Sandy Hook, NJ to Cape May, NJ.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Atlantic Coast § 7.35 Sandy Hook, NJ to Cape May, NJ. (a) A line drawn from Shark River Inlet North Breakwater Light “2” to Shark River Inlet South Breakwater Light “1”. (b) A line drawn from Manasquan...

  13. 46 CFR 7.35 - Sandy Hook, NJ to Cape May, NJ.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Atlantic Coast § 7.35 Sandy Hook, NJ to Cape May, NJ. (a) A line drawn from Shark River Inlet North Breakwater Light “2” to Shark River Inlet South Breakwater Light “1”. (b) A line drawn from Manasquan...

  14. Spirochaete flagella hook proteins self-catalyse a lysinoalanine covalent crosslink for motility.

    PubMed

    Miller, Michael R; Miller, Kelly A; Bian, Jiang; James, Milinda E; Zhang, Sheng; Lynch, Michael J; Callery, Patrick S; Hettick, Justin M; Cockburn, Andrew; Liu, Jun; Li, Chunhao; Crane, Brian R; Charon, Nyles W

    2016-08-08

    Spirochaetes are bacteria responsible for several serious diseases, including Lyme disease (Borrelia burgdorferi), syphilis (Treponema pallidum) and leptospirosis (Leptospira interrogans), and contribute to periodontal diseases (Treponema denticola)(1). These spirochaetes employ an unusual form of flagella-based motility necessary for pathogenicity; indeed, spirochaete flagella (periplasmic flagella) reside and rotate within the periplasmic space(2-11). The universal joint or hook that links the rotary motor to the filament is composed of ∼120-130 FlgE proteins, which in spirochaetes form an unusually stable, high-molecular-weight complex(9,12-17). In other bacteria, the hook can be readily dissociated by treatments such as heat(18). In contrast, spirochaete hooks are resistant to these treatments, and several lines of evidence indicate that the high-molecular-weight complex is the consequence of covalent crosslinking(12,13,17). Here, we show that T. denticola FlgE self-catalyses an interpeptide crosslinking reaction between conserved lysine and cysteine, resulting in the formation of an unusual lysinoalanine adduct that polymerizes the hook subunits. Lysinoalanine crosslinks are not needed for flagellar assembly, but they are required for cell motility and hence infection. The self-catalytic nature of FlgE crosslinking has important implications for protein engineering, and its sensitivity to chemical inhibitors provides a new avenue for the development of antimicrobials targeting spirochaetes.

  15. A double standard for "Hooking Up": How far have we come toward gender equality?

    PubMed

    Allison, Rachel; Risman, Barbara J

    2013-09-01

    While sexual attitudes have liberalized in the past half century, research is mixed as to whether attitudes have become less gendered over time. Recent studies on college students' sexual and romantic relationships suggest that a sexual double standard continues to organize sexuality on many campuses. Data from the Online College Social Life Survey shed light on students' evaluation of casual sex, or "hooking up." In addition to exploring gendered attitudinal patterns, we use gender structure theory to explore how individual characteristics and normative expectations of campus group affiliations shape attitudes. While three quarters of students do not hold different standards for men and women's hooking up, attitudes are more conservative than liberal, with almost half of students losing respect for men and women who hook up "a lot." However, men are more likely to hold a traditional double standard, while women are more likely to espouse egalitarian conservative attitudes. Individual characteristics, including age, religion, race, social class and sexual orientation are frequently related to sexual attitudes, as are number of hook ups, fraternity/sorority affiliation and varsity athletic participation.

  16. 46 CFR 7.35 - Sandy Hook, NJ to Cape May, NJ.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Atlantic Coast § 7.35 Sandy Hook, NJ to Cape May, NJ. (a) A line drawn from Shark River Inlet North Breakwater Light “2” to Shark River Inlet South Breakwater Light “1”. (b) A line drawn from Manasquan...

  17. 50 CFR 660.716 - Surface hook-and-line fishery. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Surface hook-and-line fishery. 660.716 Section 660.716 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES...

  18. Expression and functional characterization of Xhmg-at-hook genes in Xenopus laevis.

    PubMed

    Macrì, Simone; Sgarra, Riccardo; Ros, Gloria; Maurizio, Elisa; Zammitti, Salvina; Milani, Ornella; Onorati, Marco; Vignali, Robert; Manfioletti, Guidalberto

    2013-01-01

    High Mobility Group A proteins (HMGA1 and HMGA2) are architectural nuclear factors involved in development, cell differentiation, and cancer formation and progression. Here we report the cloning, developmental expression and functional analysis of a new multi-AT-hook factor in Xenopus laevis (XHMG-AT-hook) that exists in three different isoforms. Xhmg-at-hook1 and 3 isoforms, but not isoform 2, are expressed throughout the entire development of Xenopus, both in the maternal and zygotic phase. Localized transcripts are present in the animal pole in the early maternal phase; during the zygotic phase, mRNA can be detected in the developing central nervous system (CNS), including the eye, and in the neural crest. We show evidence that XHMG-AT-hook proteins differ from typical HMGA proteins in terms of their properties in DNA binding and in protein/protein interaction. Finally, we provide evidence that they are involved in early CNS development and in neural crest differentiation.

  19. Symposium of Hope: Recovery and Resiliency after the Sandy Hook Tragedy. Crisis Management

    ERIC Educational Resources Information Center

    Zenere, Frank J.

    2013-01-01

    On February 27 and 28, 2013, The Symposium of Hope: Recovery and Resilience after the Sandy Hook Tragedy, was held in Danbury, Connecticut. The event was hosted by the United Way of Western Connecticut and Western Connecticut State University. Frank J. Zenere, school psychologist and crisis team member in the Division of Student Services of the…

  20. The Sandy Hook Elementary School shooting as tipping point: "This Time Is Different".

    PubMed

    Shultz, James M; Muschert, Glenn W; Dingwall, Alison; Cohen, Alyssa M

    2013-01-01

    Among rampage shooting massacres, the Sandy Hook Elementary School shooting on December 14, 2012 galvanized public attention. In this Commentary we examine the features of this episode of gun violence that has sparked strong reactions and energized discourse that may ultimately lead toward constructive solutions to diminish high rates of firearm deaths and injuries in the United States.

  1. Assessing College Students' Autonomy over Smoking with the Hooked on Nicotine Checklist

    ERIC Educational Resources Information Center

    Wellman, Robert; McMillen, Robert; DiFranza, Joseph

    2008-01-01

    Objective, Participants, and Methods: In this study, the authors explored the psychometric properties of the Hooked on Nicotine Checklist (HONC) among 300 college students who were current smokers. The HONC is a 10-item survey instrument designed to measure diminished autonomy over smoking, a key aspect of dependence. Autonomy is diminished when…

  2. Failure Analysis of a Missile Locking Hook from the F-14 Jet

    DTIC Science & Technology

    1989-09-01

    Stress Corrosion Cracking and Hydrogen Embrittlement ........................ 38 Corrosion Fatigue ................................................. 38...reaction which was the cleaning mechanism in this process. Many of the cracks had initiated at stress concentration areas (such as corrosion pits) along the... stress corrosion cracking , hydrogen embrittlement, and corrosion fatigue, which will be discussed later in further detail in regard to the missile hook

  3. Cheating, Hooking Up, and Attention to Romantic Alternatives among College Students

    ERIC Educational Resources Information Center

    Buri, John R.; Cromett, Cristina E.; Pappas, Sarah J.

    2014-01-01

    While numerous studies have emphasized more situational factors related to cheating, hooking up, and attention to romantic alternatives (e.g., alcohol use, need fulfillment, opportunity), the present findings support Finkel el al.'s (2012) argument for greater attentiveness to personal factors intrinsic to the individual that may influence…

  4. Diagnostic Value of Hook Wire Localization Technique for Non-Palpable Breast Lesions

    PubMed Central

    Demiral, Gokhan; Senol, Metin; Bayraktar, Baris; Ozturk, Hasan; Celik, Yahya; Boluk, Salih

    2016-01-01

    Background The aim of this study was to investigate the validity of hook wire localization biopsy for non-palpable breast lesions which were detected by ultrasonography (USG) or mammography (MMG). Methods In this retrospective study, USG or MMG-guided hook wire localization technique was performed on 83 patients who had non-palpable breast lesions. Then histopathological examination was performed on surgically removed specimens. All patients’ mammograms or ultrasonograms were categorized using Breast Imaging-Reporting and Data System (BI-RADS) classification. Results Radiologically, 27 (32.53%) patients were classified as BI-RADS 3, 49 (59.04%) BI-RADS 4, one (1.2%) BIRADS 5 and six (7.23%) BI-RADS 0. Histopathological results were benign in 68 (81.9%) and malignant in 15 (18.1%) patients. Twenty-seven patients were classified as BI-RADS 3 and definitive diagnoses for all were benign. Besides, 49 patients were classified as BI-RADS 4 and histopathologically 14 of them were reported as malignant, and 35 as benign. Sensitivity of MMG was 93% and specificity was 55%. For USG, the sensitivity was 100% and the specificity was 73%. Conclusion In early diagnosis of breast cancer, the validity of the imaging-guided hook wire localization biopsy of non-palpable breast lesions has been proved. The cooperation of surgeon, radiologist and pathologist increases the successfull results of hook wire localization technique. PMID:27081425

  5. Tracks in the Sand: Hooke's Pendulum "Cum Grano Salis"

    ERIC Educational Resources Information Center

    Babovic, Vukota; Babovic, Miloš

    2014-01-01

    The history of science remembers more than just formal facts about scientific discoveries. These side stories are often inspiring. One of them, the story of an unfulfilled death wish of Jacob Bernoulli regarding spirals, inspired us to look around ourselves. And we saw natural spirals around us, which led to the creation of a Hooke's…

  6. Risk Factors and Consequences of Unwanted Sex among University Students: Hooked up, Alcohol, and Stress Response

    ERIC Educational Resources Information Center

    Flack, William F., Jr.; Daubman, Kimberly A.; Caron, Marcia L.; Asadorian, Jenica A.; D'Aureli, Nicole R.; Gigliotti, Shannon N.; Hall, Anna T.; Kiser, Sarah; Stine, Erin R.

    2007-01-01

    This is the first study of unwanted sexual experiences in the collegiate "hooking-up" culture. In a representative sample of 178 students at a small liberal arts university. Twenty-three percent of women and 7% of men surveyed reported one or more experiences of unwanted sexual intercourse. Seventy-eight percent of unwanted vaginal, anal, and oral…

  7. Hooke and Jeeves based multilevel coordinate search to globally solving nonsmooth problems

    NASA Astrophysics Data System (ADS)

    Costa, M. Fernanda P.; Rocha, Ana Maria A. C.; Fernandes, Edite M. G. P.

    2013-10-01

    In this paper, we present a derivative-free multilevel coordinate search (MCS) approach, that relies on the Hooke and Jeeves local search, for globally solving bound constrained optimization problems. Numerical experiments show that the proposed algorithm is effective in solving benchmark problems, when compared with the well-known solvers MCS and DIRECT.

  8. 50 CFR 660.716 - Surface hook-and-line fishery. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Surface hook-and-line fishery. 660.716 Section 660.716 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES...

  9. Rose Prickles and Asparagus Spines--Different Hook Structures as Attachment Devices in Climbing Plants.

    PubMed

    Gallenmüller, Friederike; Feus, Amélie; Fiedler, Kathrin; Speck, Thomas

    2015-01-01

    Functional morphology and biomechanical properties of hook structures functioning as attachment devices in the leaning climbers Rosa arvensis, Rosa arvensis 'Splendens', Asparagus falcatus and Asparagus setaceus are analysed in order to investigate the variability in closely related species as well as convergent developments of hook structure and properties in distant systematic lineages (monocots and dicots). Prickles and spines were characterised by their size, orientation and the maximum force measured at failure in mechanical tests performed with traction forces applied at different angles. In Rosa arvensis and Rosa arvensis 'Splendens' three types of prickles differing largely in geometrical and mechanical properties are identified (prickles of the wild species and two types of prickles in the cultivar). In prickles of Rosa arvensis no particular orientation of the prickle tip is found whereas in the cultivar Rosa arvensis 'Splendens' prickles gradually gain a downward-orientation due to differential growth in the first weeks of their development. Differences in mechanical properties and modes of failure are correlated to geometrical parameters. In Asparagus falcatus and Asparagus setaceus spines are composed of leaf tissue, stem tissue and tissue of the axillary bud. Between species spines differ in size, orientation, distribution along the stem, tissue contributions and mechanical properties. The prickles of Rosa arvensis and its cultivar and the spines of the studied Asparagus species have several traits in common: (1) a gradual change of cell size and cell wall thickness, with larger cells in the centre and smaller thick-walled cells at the periphery of the hooks, (2) occurrence of a diversity of shape and geometry within one individual, (3) failure of single hooks when submitted to moderate mechanical stresses (Fmax/basal area < 35 N/mm²) and (4) failure of the hooks without severe stem damage (at least in the tested wild species).

  10. Rose Prickles and Asparagus Spines – Different Hook Structures as Attachment Devices in Climbing Plants

    PubMed Central

    Fiedler, Kathrin

    2015-01-01

    Functional morphology and biomechanical properties of hook structures functioning as attachment devices in the leaning climbers Rosa arvensis, Rosa arvensis ‘Splendens‘, Asparagus falcatus and Asparagus setaceus are analysed in order to investigate the variability in closely related species as well as convergent developments of hook structure and properties in distant systematic lineages (monocots and dicots). Prickles and spines were characterised by their size, orientation and the maximum force measured at failure in mechanical tests performed with traction forces applied at different angles. In Rosa arvensis and Rosa arvensis ‘Splendens‘ three types of prickles differing largely in geometrical and mechanical properties are identified (prickles of the wild species and two types of prickles in the cultivar). In prickles of Rosa arvensis no particular orientation of the prickle tip is found whereas in the cultivar Rosa arvensis ‘Splendens‘ prickles gradually gain a downward-orientation due to differential growth in the first weeks of their development. Differences in mechanical properties and modes of failure are correlated to geometrical parameters. In Asparagus falcatus and Asparagus setaceus spines are composed of leaf tissue, stem tissue and tissue of the axillary bud. Between species spines differ in size, orientation, distribution along the stem, tissue contributions and mechanical properties. The prickles of Rosa arvensis and its cultivar and the spines of the studied Asparagus species have several traits in common: (1) a gradual change of cell size and cell wall thickness, with larger cells in the centre and smaller thick-walled cells at the periphery of the hooks, (2) occurrence of a diversity of shape and geometry within one individual, (3) failure of single hooks when submitted to moderate mechanical stresses (Fmax/basal area < 35 N/mm²) and (4) failure of the hooks without severe stem damage (at least in the tested wild species). PMID

  11. Measurement of PLGA-NP interaction with single smooth muscle cells using optical tweezers

    NASA Astrophysics Data System (ADS)

    Gu, Ling; Mondal, Argha; Homayoni, Homa; Nguyen, Kytai; Mohanty, Samarendra

    2012-10-01

    For intervention of cardiovascular diseases, biodegradable and biocompatible, poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NP) are emerging as agents of choice for controlled and targeted drug delivery. Therefore development of PLGA-NP with optimal physico-chemical properties will allow efficient binding and thus delivery of drug to targeted cells under various patho-physiological conditions. The force kinetics and its dependence on size of the NPs will be crucial for designing the NPs. Since optical tweezers allow non-contact, highly sensitive force measurement with high spatial and temporal resolution, we utilized it for studying interaction forces between magnetic PLGA nanoparticles with smooth muscle cells (SMC). In order to investigate effect of size, interaction force for 200 to 1100nm PLGA NP was measured. For similar interaction duration, the force was found to be higher with increase in size. The rupture force was found to depend on time of interaction of SMC with NPs.

  12. Optically-driven red blood cell rotor in linearly polarized laser tweezers

    NASA Astrophysics Data System (ADS)

    Khan, Manas; Mohanty, Samarendra K.; Sood, A. K.

    2005-11-01

    We have constructed a dual trap optical tweezers set-up around an inverted microscope where both the traps can be independently controlled and manipulated in all the three dimensions. Here we report our observations on rotation of red blood cells (RBCs) in a linearly polarized optical trap. Red blood cells deform and become twisted in hypertonic phosphate buffer saline and when trapped, experience an unbalanced radiation pressure force. The torque generated from the unbalanced force causes the trapped RBC to rotate. Addition of Ca^{++} ions in the solution, keeping the osmolarity same, makes the cell membranes stiffer and the cells deform less. Thus the speed of rotation of the red blood cells can be controlled, as less deformation and in turn less asymmetry in shape produces less torque under the radiation pressure resulting in slower rotation at the same laser power.

  13. Inhibition of Huntingtin Exon-1 Aggregation by the Molecular Tweezer CLR01.

    PubMed

    Vöpel, Tobias; Bravo-Rodriguez, Kenny; Mittal, Sumit; Vachharajani, Shivang; Gnutt, David; Sharma, Abhishek; Steinhof, Anne; Fatoba, Oluwaseun; Ellrichmann, Gisa; Nshanian, Michael; Heid, Christian; Loo, Joseph A; Klärner, Frank-Gerrit; Schrader, Thomas; Bitan, Gal; Wanker, Erich E; Ebbinghaus, Simon; Sanchez-Garcia, Elsa

    2017-04-13

    Huntington's disease is a neurodegenerative disorder associated with the expansion of the polyglutamine tract in the exon-1 domain of the huntingtin protein (htt(e1)). Above a threshold of 37 glutamine residues, htt(e1) starts to aggregate in a nucleation-dependent manner. A 17-residue N-terminal fragment of htt(e1) (N17) has been suggested to play a crucial role in modulating the aggregation propensity and toxicity of htt(e1). Here we identify N17 as a potential target for novel therapeutic intervention using the molecular tweezer CLR01. A combination of biochemical experiments and computer simulations shows that binding of CLR01 induces structural rearrangements within the htt(e1) monomer and inhibits htt(e1) aggregation, underpinning the key role of N17 in modulating htt(e1) toxicity.

  14. Detection of doxorubicin-induced apoptosis of leukemic T-lymphocytes by laser tweezers Raman spectroscopy

    PubMed Central

    Moritz, Tobias J.; Taylor, Douglas S.; Krol, Denise M.; Fritch, John; Chan, James W.

    2010-01-01

    Laser tweezers Raman spectroscopy (LTRS) was used to acquire the Raman spectra of leukemic T lymphocytes exposed to the chemotherapy drug doxorubicin at different time points over 72 hours. Changes observed in the Raman spectra were dependent on drug exposure time and concentration. The sequence of spectral changes includes an intensity increase in lipid Raman peaks, followed by an intensity increase in DNA Raman peaks, and finally changes in DNA and protein (phenylalanine) Raman vibrations. These Raman signatures are consistent with vesicle formation, cell membrane blebbing, chromatin condensation, and the cytoplasm of dead cells during the different stages of drug-induced apoptosis. These results suggest the potential of LTRS as a real-time single cell tool for monitoring apoptosis, evaluating the efficacy of chemotherapeutic treatments, or pharmaceutical testing. PMID:21258536

  15. Micro-particle manipulation by single beam acoustic tweezers based on hydrothermal PZT thick film

    PubMed Central

    Zhu, Benpeng; Xu, Jiong; Li, Ying; Wang, Tian; Xiong, Ke; Lee, Changyang; Yang, Xiaofei; Shiiba, Michihisa; Takeuchi, Shinichi; Zhou, Qifa; Shung, K. Kirk

    2016-01-01

    Single-beam acoustic tweezers (SBAT), used in laboratory-on-a-chip (LOC) device has promising implications for an individual micro-particle contactless manipulation. In this study, a freestanding hydrothermal PZT thick film with excellent piezoelectric property (d33 = 270pC/N and kt = 0.51) was employed for SBAT applications and a press-focusing technology was introduced. The obtained SBAT, acting at an operational frequency of 50MHz, a low f-number (∼0.9), demonstrated the capability to trap and manipulate a micro-particle sized 10μm in the distilled water. These results suggest that such a device has great potential as a manipulator for a wide range of biomedical and chemical science applications. PMID:27014504

  16. Studies of cochlear outer hair cell membrane mechanics using optical tweezers

    NASA Astrophysics Data System (ADS)

    Murdock, David R.; Ermilov, Sergey A.; Brownell, William E.; Anvari, Bahman

    2003-06-01

    An optical tweezers system was used to study the mechanical characteristics of outer hair cell (OHC) and human embryonic kidney (HEK) cell plasma membranes. The effect of the cationic amphipath chlorpromazine (CPZ) on the equilibrium tethering force, (Feq) force relaxation time constant,(τ) and effective membrane viscosity (ηeff) was measured. The Feq for the OHC lateral wall plasma membrane was ~60 pN and was unchanged by addition of CPZ. A significantly greater τ value was observed in CPZ-treated OHCs (30.5 +/- 12.6 s) than in control OHCs (19.0 +/- 13.2 s). The Feq and τ values for control HEK cells were >60% lower than the respective OHC values but increased by ~3 times following CPZ addition. Effective viscosity ranged between 1.49-1.81 pN•s/μm for CPZ-treated OHCs. This represents a decrease from reported control OHC membrane viscosities.

  17. Optical tweezers study of viscoelastic properties in the outer hair cell plasma membrane

    NASA Astrophysics Data System (ADS)

    Murdock, David R.; Ermilov, Sergey A.; Qian, Feng; Brownell, William E.; Anvari, Bahman

    2004-06-01

    An optical tweezers system was used to study the mechanical characteristics of the outer hair cell (OHC) lateral wall by forming plasma membrane tethers. A 2nd order generalized Kelvin model was applied to describe the viscoelastic behavior of OHC membrane tethers. The measured parameters included equilibrium tethering force, (Feq), force relaxation times (τ), stiffness values (κ), and coefficients of friction (μ). An analysis of force relaxation in membrane tethers indicated that the force decay is a biphasic process containing both an elastic and a viscous phase. In general, we observed an overall negative trend in the measured parameters upon application of the cationic amphipath chlorpromazine (CPZ). CPZ was found to cause up to a 40 pN reduction in Feq in OHCs. A statistically significant reduction in relaxation times and coefficients of friction was also observed, suggesting an increase in rate of force decay and a decrease in plasma membrane viscosity.

  18. Freely orbiting magnetic tweezers to directly monitor changes in the twist of nucleic acids

    PubMed Central

    Lipfert, Jan; Wiggin, Matthew; Kerssemakers, Jacob W.J.; Pedaci, Francesco; Dekker, Nynke H.

    2011-01-01

    The double-stranded nature of DNA links its replication, transcription and repair to rotational motion and torsional strain. Magnetic tweezers (MT) are a powerful single-molecule technique to apply both forces and torques to individual DNA or RNA molecules. However, conventional MT do not track rotational motion directly and constrain the free rotation of the nucleic acid tether. Here we present freely orbiting MT (FOMT) that allow the measurement of equilibrium fluctuations and changes in the twist of tethered nucleic acid molecules. Using a precisely aligned vertically oriented magnetic field, FOMT enable tracking of the rotation angle from straight forward (x,y)-position tracking and permits the application of calibrated stretching forces, without biasing the tether's free rotation. We utilize FOMT to measure the force-dependent torsional stiffness of DNA from equilibrium rotational fluctuations and to follow the assembly of recombination protein A filaments on DNA. PMID:21863006

  19. Optical levitation and manipulation of stuck particles with pulsed optical tweezers.

    PubMed

    Ambardekar, Amol Ashok; Li, Yong-Qing

    2005-07-15

    We report on optical levitation and manipulation of microscopic particles that are stuck on a glass surface with pulsed optical tweezers. An infrared pulse laser at 1.06 microm was used to generate a large gradient force (up to 10(-9) N) within a short duration (approximately 45 micros) that overcomes the adhesive interaction between the particles and the glass surface. Then a low-power continuous-wave diode laser at 785 nm was used to capture and manipulate the levitated particle. We have demonstrated that both stuck dielectric and biological micrometer-sized particles, including polystyrene beads, yeast cells, and Bacillus cereus bacteria, can be levitated and manipulated with this technique. We measured the single-pulse levitation efficiency for 2.0 microm polystyrene beads as a function of the pulse energy and of the axial displacement from the stuck particle to the pulsed laser focus, which was as high as 88%.

  20. Microfluidic platform combining droplets and magnetic tweezers: application to HER2 expression in cancer diagnosis

    PubMed Central

    Ferraro, Davide; Champ, Jérôme; Teste, Bruno; Serra, Marco; Malaquin, Laurent; Viovy, Jean-Louis; de Cremoux, Patricia; Descroix, Stephanie

    2016-01-01

    The development of precision medicine, together with the multiplication of targeted therapies and associated molecular biomarkers, call for major progress in genetic analysis methods, allowing increased multiplexing and the implementation of more complex decision trees, without cost increase or loss of robustness. We present a platform combining droplet microfluidics and magnetic tweezers, performing RNA purification, reverse transcription and amplification in a fully automated and programmable way, in droplets of 250nL directly sampled from a microtiter-plate. This platform decreases sample consumption about 100 fold as compared to current robotized platforms and it reduces human manipulations and contamination risk. The platform’s performance was first evaluated on cell lines, showing robust operation on RNA quantities corresponding to less than one cell, and then clinically validated with a cohort of 21 breast cancer samples, for the determination of their HER2 expression status, in a blind comparison with an established routine clinical analysis. PMID:27157697

  1. Characterization of the mechanical properties of HL-1 cardiomyocytes with high throughput magnetic tweezers

    SciTech Connect

    Chen, La; Maybeck, Vanessa; Offenhäusser, Andreas; Krause, Hans-Joachim

    2015-08-03

    We characterized the mechanical properties of cardiomyocyte-like HL-1 cells using our recently developed multi-pole magnetic tweezers. With the optimized design, both high force and high throughput are achieved at the same time. Force up to 100 pN can be applied on a 1 μm diameter superparamagnetic bead in a workspace with 60 μm radius, which is encircled symmetrically by 3 sharp magnetic tips. By adjusting the coil currents, both the strength and direction of force can be controlled. The result shows that both viscosity and shear elastic modulus of HL-1 cells exhibit an approximately log-normal distribution. The cells became stiffer as they matured, consistent with a transition from proliferating cells to contractile muscle tissue. Moreover, the mechanical properties of HL-1 cells show high heterogeneity, which agrees well with their physiological structure.

  2. 3D Manipulation of Protein Microcrystals with Optical Tweezers for X-ray Crystallography

    NASA Astrophysics Data System (ADS)

    Hikima, T.; Hashimoto, K.; Murakami, H.; Ueno, G.; Kawano, Y.; Hirata, K.; Hasegawa, K.; Kumasaka, T.; Yamamoto, M.

    2013-03-01

    In some synchrotron facilities such as SPring-8, X-ray microbeams have been utilized for protein crystallography, allowing users to collect diffraction data from a protein microcrystal. Usually, a protein crystal is picked up manually from a crystallization droplet. However it is very difficult to manipulate the protein microcrystals which are very small and fragile against a shock and changes of temperature and solvent condition. We have been developing an automatic system applying the optical tweezers with two lensed fiber probes to manipulate the fragile protein microcrystal. The system succeeded in trapping a crystal and levitating it onto the cryoloop in the solvent. X-ray diffraction measurement for the manipulated protein microcrystals indicated that laser irradiation and trap with 1064nm wavelength hardly affected the result of X-ray structural analysis.

  3. Identification of volume phase transition of a single microgel particle using optical tweezers

    NASA Astrophysics Data System (ADS)

    Karthickeyan, D.; Gupta, Deepak K.; Tata, B. V. R.

    2016-10-01

    Poly (N-isopropyl acrylamide-co-acrylic acid) (PNIPAM-co-Aac) microgel particles are pH responsive and exhibit volume phase transition (VPT) upon variation of pH. Dynamic light scattering (DLS) is used conventionally to identify VPT and requires a dilute suspension with particle concentration ˜107 particles cm-3 and if particles are polydisperse in nature, DLS data interpretation is relatively difficult. Here we show that optical tweezers allow one to measure the VPT of a single microgel particle by measuring the optical trap stiffness, κ of trapped particle as a function of pH. We report here a sudden change in κ at VPT, which is shown to arise from a sudden decrease in particle diameter with a concomitant increase in the refractive index of the particle at VPT.

  4. Optical tweezers based active microrheology of sodium polystyrene sulfonate (NaPSS).

    PubMed

    Chiang, Chia-Chun; Wei, Ming-Tzo; Chen, Yin-Quan; Yen, Pei-Wen; Huang, Yi-Chiao; Chen, Jun-Yeh; Lavastre, Olivier; Guillaume, Husson; Guillaume, Darsy; Chiou, Arthur

    2011-04-25

    We used oscillatory optical tweezers to investigate the microrheological properties of Sodium polystyrene sulfonate (NaPSS; Mw = 70 kDa) polymer solutions with different concentrations from 0.001 mM to 10 mM in terms of elastic modulus G'(ω) and loss modulus G"(ω) as a function of angular frequency (ω) in the range of 6 rad/s to 6000 rad/s. The viscoelastic properties (including zero-shear-rate viscosity, crossing frequency and transition frequency) as a function of polymer concentration, deduced from our primary data, reveal the subtle structural changes in the polymer solutions as the polymer concentration increases from dilute to semi-dilute regimes, passing through the critical micelle formation concentration and the polymer overlapping concentration. The experimental results are consistent with the Maxwell model in some regime, and with the Rouse model in other, indicating the transient network character and the micelles formation in different regimes.

  5. Surface modes of a sessile water drop: An optical tweezer based study

    NASA Astrophysics Data System (ADS)

    Ghosh, Shankar; Sharma, Prerna; Bhattacharya, S.

    2007-11-01

    A high-precision method to study the dynamics of two-fluid interfaces using an optical tweezer and a phase-sensitive detection technique are described. The disturbances set up at the interface are studied by analyzing the motion of an optically trapped particle in the bulk of the fluid, i.e., away from the interface. The usefulness of the technique is demonstrated for the well-known problem of a horizontally vibrated sessile liquid drop. The vibrational modes of the liquid drop excited by sinusoidally vibrating the support in a horizontal plane appear as resonances in the motion of the trapped particle. The nature of the resonance is studied in detail by measuring the real part, the imaginary part, and the phase response of the motion of the particle as a function of the "effective" size of the liquid drop. Excellent quantitative agreement with the theoretically predicted values of the eigenfrequencies and damping of the surface modes is obtained.

  6. Surface modes of a sessile water drop: an optical tweezer based study.

    PubMed

    Ghosh, Shankar; Sharma, Prerna; Bhattacharya, S

    2007-11-01

    A high-precision method to study the dynamics of two-fluid interfaces using an optical tweezer and a phase-sensitive detection technique are described. The disturbances set up at the interface are studied by analyzing the motion of an optically trapped particle in the bulk of the fluid, i.e., away from the interface. The usefulness of the technique is demonstrated for the well-known problem of a horizontally vibrated sessile liquid drop. The vibrational modes of the liquid drop excited by sinusoidally vibrating the support in a horizontal plane appear as resonances in the motion of the trapped particle. The nature of the resonance is studied in detail by measuring the real part, the imaginary part, and the phase response of the motion of the particle as a function of the "effective" size of the liquid drop. Excellent quantitative agreement with the theoretically predicted values of the eigenfrequencies and damping of the surface modes is obtained.

  7. Controlled modulation of laser beam and dynamic patterning of colloidal particles using optical tweezers

    NASA Astrophysics Data System (ADS)

    Singh, Brijesh Kumar; Singh Mehta, Dalip; Kumar, Ranjeet; Senthilkumaran, Paramasivam

    2016-02-01

    We present controlled generation of complex-structured beam profiles using diffractive optical element and demonstrate multiple dynamic trapping of colloidal particles. The phase element is programmed to generate various tailored optical fields having structures, similar to that of number three, spiral, and circle but in a tractable manner. Thus, the generated spatially tailored optical fields are confined to focal volume in optical tweezers. This enabled real-time trapping of multiple microscopic objects whereby its transverse organization was controlled in a dynamic manner from one structure to another with the help of spatial light modulator. Such a controlled beam shaping finds potential applications in biophotonics, super resolution imaging, and measurement of biophysical parameters, cell sorting, and micro-manipulation of colloidal particles.

  8. Coherence and Raman sideband cooling of a single atom in an optical tweezer.

    PubMed

    Thompson, J D; Tiecke, T G; Zibrov, A S; Vuletić, V; Lukin, M D

    2013-03-29

    We investigate quantum control of a single atom in a tightly focused optical tweezer trap. We show that inevitable spatially varying polarization gives rise to significant internal-state decoherence but that this effect can be mitigated by an appropriately chosen magnetic bias field. This enables Raman sideband cooling of a single atom close to its three-dimensional ground state (vibrational quantum numbers n(x)=n(y)=0.01, n(z)=8) even for a trap beam waist as small as w=900  nm. The small atomic wave packet with δx=δy=24  nm and δz=270  nm represents a promising starting point for future hybrid quantum systems where atoms are placed in close proximity to surfaces.

  9. Stretching single DNA molecules to demonstrate high-force capabilities of holographic optical tweezers.

    PubMed

    Farré, Arnau; van der Horst, Astrid; Blab, Gerhard A; Downing, Benjamin P B; Forde, Nancy R

    2010-04-01

    The well calibrated force-extension behaviour of single double-stranded DNA molecules was used as a standard to investigate the performance of phase-only holographic optical tweezers at high forces. Specifically, the characteristic overstretch transition at 65 pN was found to appear where expected, demonstrating (1) that holographic optical trap calibration using thermal fluctuation methods is valid to high forces; (2) that the holographic optical traps are harmonic out to >250 nm of 2.1 mum particle displacement; and (3) that temporal modulations in traps induced by the spatial light modulator (SLM) do not affect the ability of optical traps to hold and steer particles against high forces. These studies demonstrate a new high-force capability for holographic optical traps achievable by SLM technologies.

  10. Study of a colloidal sphere near flat walls using oscillating optical tweezers

    NASA Astrophysics Data System (ADS)

    Ha, Chungil; Ou-Yang, H. Daniel; Pak, Hyuk Kyu

    2009-11-01

    We study the dynamics of a micron-sized colloidal sphere in two cases; one is for a particle near a single flat wall and the other is for a particle confined between two parallel flat walls. In this geometry, the force felt by a moving particle is quite different from that of a moving particle in unbounded space. Even though the presence of wall(s) complicates the flow field surrounding the colloidal sphere, the dynamics of a colloidal sphere near flat walls provides a model system with which to understand the phenomenon of more complex systems whose boundaries can be modeled as effective walls.[1] In this work, hydrodynamic interactions of colloidal sphere with nearby plat wall(s) are studied by using oscillating optical tweezers and compared with known theories and other experimental results using different techniques.

  11. Evaluating cell matrix mechanics using an integrated nonlinear optical tweezer-confocal imaging system

    NASA Astrophysics Data System (ADS)

    Peng, Berney; Alonzo, Carlo A. C.; Xia, Lawrence; Speroni, Lucia; Georgakoudi, Irene; Soto, Ana M.; Sonnenschein, Carlos; Cronin-Golomb, Mark

    2013-09-01

    Biomechanics plays a central role in breast epithelial morphogenesis. In this study we have used 3D cultures in which normal breast epithelial cells are able to organize into rounded acini and tubular ducts, the main structures found in the breast tissue. We have identified fiber organization as a main determinant of ductal organization. While bulk rheological properties of the matrix seem to play a negligible role in determining the proportion of acini versus ducts, local changes may be pivotal in shape determination. As such, the ability to make microscale rheology measurements coupled with simultaneous optical imaging in 3D cultures can be critical to assess the biomechanical factors underlying epithelial morphogenesis. This paper describes the inclusion of optical tweezers based microrheology in a microscope that had been designed for nonlinear optical imaging of collagen networks in ECM. We propose two microrheology methods and show preliminary results using a gelatin hydrogel and collagen/Matrigel 3D cultures containing mammary gland epithelial cells.

  12. Mechanism of termination of bacteriophage DNA packaging investigated with optical tweezers

    NASA Astrophysics Data System (ADS)

    delToro, Damian J.; Smith, Douglas E.

    2012-10-01

    The genomes of many dsDNA viruses are replicated by a mechanism that produces a long concatemer of multiple genomes. These viruses utilize multifunctional molecular motor complexes referred to as "terminases" that can excise a unit genome length of DNA and package it into preformed viral shells. Remarkably, the terminase motor can initiate packaging at the appropriate start point, translocate DNA, sense when a sufficient length has been packaged, and then switch into a mode where it arrests and cleaves the DNA to release a filled virus particle. We have recently developed an improved method to measure single phage lambda DNA packaging using dual-trap optical tweezers and pre-stalled motor-DNA-procapsid complexes. We are applying this method to test proposed mechanisms for the sensor that triggers termination; specifically a velocity-monitor model vs. energy-monitor model vs. capsid-filling monitor model.

  13. Microfluidic platform combining droplets and magnetic tweezers: application to HER2 expression in cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Ferraro, Davide; Champ, Jérôme; Teste, Bruno; Serra, Marco; Malaquin, Laurent; Viovy, Jean-Louis; de Cremoux, Patricia; Descroix, Stephanie

    2016-05-01

    The development of precision medicine, together with the multiplication of targeted therapies and associated molecular biomarkers, call for major progress in genetic analysis methods, allowing increased multiplexing and the implementation of more complex decision trees, without cost increase or loss of robustness. We present a platform combining droplet microfluidics and magnetic tweezers, performing RNA purification, reverse transcription and amplification in a fully automated and programmable way, in droplets of 250nL directly sampled from a microtiter-plate. This platform decreases sample consumption about 100 fold as compared to current robotized platforms and it reduces human manipulations and contamination risk. The platform’s performance was first evaluated on cell lines, showing robust operation on RNA quantities corresponding to less than one cell, and then clinically validated with a cohort of 21 breast cancer samples, for the determination of their HER2 expression status, in a blind comparison with an established routine clinical analysis.

  14. Implementation and Tuning of an Optical Tweezers Force-Clamp Feedback System.

    PubMed

    Bugiel, Michael; Jannasch, Anita; Schäffer, Erik

    2017-01-01

    Feedback systems can be used to control the value of a system variable. In optical tweezers, active feedback is often implemented to either keep the position or tension applied to a single biomolecule constant. Here, we describe the implementation of the latter: an optical force-clamp setup that can be used to study the motion of processive molecular motors under a constant load. We describe the basics of a software-implemented proportional-integral-derivative (PID) controller, how to tune it, and how to determine its optimal feedback rate. Limitations, possible feed-forward applications, and extensions into two- and three-dimensional optical force clamps are discussed. The feedback is ultimately limited by thermal fluctuations and the compliance of the involved molecules. To investigate a particular mechanical process, understanding the basics and limitations of the feedback system will be helpful for choosing the proper feedback hardware, for optimizing the system parameters, and for the design of the experiment.

  15. Rapid feedback control and stabilization of an optical tweezers with a budget microcontroller

    NASA Astrophysics Data System (ADS)

    Nino, Daniel; Wang, Haowei; Milstein, Joshua N.

    2014-09-01

    Laboratories ranging the scientific disciplines employ feedback control to regulate variables within their experiments, from the flow of liquids within a microfluidic device to the temperature within a cell incubator. We have built an inexpensive, yet fast and rapidly deployed, feedback control system that is straightforward and flexible to implement from a commercially available Arduino Due microcontroller. This is in comparison with the complex, time-consuming and often expensive electronics that are commonly implemented. As an example of its utility, we apply our feedback controller to the task of stabilizing the main trapping laser of an optical tweezers. The feedback controller, which is inexpensive yet fast and rapidly deployed, was implemented from hacking an open source Arduino Due microcontroller. Our microcontroller based feedback system can stabilize the laser intensity to a few tenths of a per cent at 200 kHz, which is an order of magnitude better than the laser's base specifications, illustrating the utility of these devices.

  16. Use of optoelectronic tweezers in manufacturing—accurate solder bead positioning

    NASA Astrophysics Data System (ADS)

    Zhang, Shuailong; Liu, Yongpeng; Juvert, Joan; Tian, Pengfei; Navarro, Jean-Claude; Cooper, Jonathan M.; Neale, Steven L.

    2016-11-01

    In this work, we analyze the use of optoelectronic tweezers (OETs) to manipulate 45 μm diameter Sn62Pb36Ag2 solder beads with light-induced dielectrophoresis force and we demonstrate high positioning accuracy. It was found that the positional deviation of the solder beads increases with the increase of the trap size. To clarify the underlying mechanism, simulations based on the integration of the Maxwell stress tensor were used to study the force profiles of OET traps with different sizes. It was found that the solder beads felt a 0.1 nN static friction or stiction force due to electrical forces pulling them towards the surface and that this force is not dependent on the size of the trap. The stiction limits the positioning accuracy; however, we show that by choosing a trap that is just larger than the solder bead sub-micron positional accuracy can be achieved.

  17. Semi-automated sorting using holographic optical tweezers remotely controlled by eye/hand tracking camera

    NASA Astrophysics Data System (ADS)

    Tomori, Zoltan; Keša, Peter; Nikorovič, Matej; Kaůka, Jan; Zemánek, Pavel

    2016-12-01

    We proposed the improved control software for the holographic optical tweezers (HOT) proper for simple semi-automated sorting. The controller receives data from both the human interface sensors and the HOT microscope camera and processes them. As a result, the new positions of active laser traps are calculated, packed into the network format and sent to the remote HOT. Using the photo-polymerization technique, we created a sorting container consisting of two parallel horizontal walls where one wall contains "gates" representing a place where the trapped particle enters into the container. The positions of particles and gates are obtained by image analysis technique which can be exploited to achieve the higher level of automation. Sorting is documented on computer game simulation and the real experiment.

  18. An active one-particle microrheometer: incorporating magnetic tweezers to total internal reflection microscopy.

    PubMed

    Gong, Xiangjun; Hua, Li; Wu, Chi; Ngai, To

    2013-03-01

    We present a novel microrheometer by incorporating magnetic tweezers in the total internal reflection microscopy (TIRM) that enables measuring of viscoelastic properties of materials near solid surface. An evanescent wave generated by a solid∕liquid interface in the TIRM is used as the incident light source in the microrheometer. When a probe particle (of a few micrometers diameter) moves near the interface, it can interact with the evanescent field and reflect its position with respect to the interface by the scattered light intensity. The exponential distance dependence of the evanescent field, on the one hand, makes this technique extremely sensitive to small changes from z-fluctuations of the probe (with a resolution of several nanometers), and on the other, it does not require imaging of the probe with high lateral resolution. Another distinct advantage is the high sensitivity in determining the z position of the probe in the absence of any labeling. The incorporated magnetic tweezers enable us to effectively manipulate the distance of the embedded particle from the interface either by a constant or an oscillatory force. The force ramp is easy to implement through a coil current ramp. In this way, the local viscous and elastic properties of a given system under different confinements can therefore be measured by resolving the near-surface particle motion. To test the feasibility of applying this microrheology to soft materials, we measured the viscoelastic properties of sucrose and poly(ethylene glycol) solutions and compared the results to bulk rheometry. In addition, we applied this technique in monitoring the structure and properties of deformable microgel particles near the flat surface.

  19. Optoelectronic tweezers for the measurement of the relative stiffness of erythrocytes

    NASA Astrophysics Data System (ADS)

    Neale, Steven L.; Mody, Nimesh; Selman, Colin; Cooper, Jonathan M.

    2012-10-01

    In this paper we describe the first use of Optoelectronic Tweezers (OET), an optically controlled micromanipulation method, to measure the relative stiffness of erythrocytes in mice. Cell stiffness is an important measure of cell health and in the case of erythrocytes, the most elastic cells in the body, an increase in cell stiffness can indicate pathologies such as type II diabetes mellitus or hypertension (high blood pressure). OET uses a photoconductive device to convert an optical pattern into and electrical pattern. The electrical fields will create a dipole within any polarisable particles in the device, such as cells, and non-uniformities of the field can be used to place unequal forces onto each side of the dipole thus moving the particle. In areas of the device where there are no field gradients, areas of constant illumination, the force on each side of the dipole will be equal, keeping the cell stationary, but as there are opposing forces on each side of the cell it will be stretched. The force each cell will experience will differ slightly so the stretching will depend on the cells polarisability as well as its stiffness. Because of this a relative stiffness rather than absolute stiffness is measured. We show that with standard conditions (20Vpp, 1.5MHz, 10mSm-1 medium conductivity) the cell's diameter changes by around 10% for healthy mouse erythrocytes and we show that due to the low light intensities required for OET, relative to conventional optical tweezers, multiple cells can be measured simultaneously.

  20. CD-sensitive Zn-porphyrin tweezer host-guest complexes, part 1: MC/OPLS-2005 computational approach for predicting preferred interporphyrin helicity.

    PubMed

    Petrovic, Ana G; Chen, Yihui; Pescitelli, Gennaro; Berova, Nina; Proni, Gloria

    2010-01-01

    This article describes a computational study on dimeric zinc porphyrin tweezer complexes with primary/secondary amines and secondary alcohols that validates the use of Optimized Potential for Liquid Simulations (OPLS-2005) as the lead computational choice for assisting the tweezer methodology in the absolute configurational assignment of organic compounds. A supramolecular, microscale approach known as the tweezer method has been widely applied in the past decade for determining the absolute configuration of chiral substrates that are difficult to study by other readily available methods. The method relies on a host/guest complexation mechanism between a porphyrin tweezer moiety and a substrate, after its conversion into a bidentate conjugate. The formation of 1:1 complexes is a stereodifferentiating process: upon complexation, the originally achiral tweezer adopts a preferential interporphyrin helicity, dictated by the absolute configuration of the chiral substrate. By correctly predicting the sign of the interporphyrin helicity in the complex, OPLS-2005 provides a correlation between the observed circular dichroism (CD) signal and the absolute configuration of the substrate. It also offers a great degree of insight into the structural factors responsible for chiral recognition and the amplitude of exciton couplets. Moreover, the preferential binding sites between the Zn-tweezer and secondary amine conjugates were revealed by using the new computational approach.