21 CFR 864.9125 - Vacuum-assisted blood collection system.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Vacuum-assisted blood collection system. 864.9125... Blood and Blood Products § 864.9125 Vacuum-assisted blood collection system. (a) Identification. A vacuum-assisted blood collection system is a device intended for medical purposes that uses a vacuum to...

21 CFR 864.9125 - Vacuum-assisted blood collection system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Vacuum-assisted blood collection system. 864.9125... Blood and Blood Products § 864.9125 Vacuum-assisted blood collection system. (a) Identification. A vacuum-assisted blood collection system is a device intended for medical purposes that uses a vacuum to...

21 CFR 864.9125 - Vacuum-assisted blood collection system.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Vacuum-assisted blood collection system. 864.9125... Blood and Blood Products § 864.9125 Vacuum-assisted blood collection system. (a) Identification. A vacuum-assisted blood collection system is a device intended for medical purposes that uses a vacuum to...

21 CFR 864.9125 - Vacuum-assisted blood collection system.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Vacuum-assisted blood collection system. 864.9125... Blood and Blood Products § 864.9125 Vacuum-assisted blood collection system. (a) Identification. A vacuum-assisted blood collection system is a device intended for medical purposes that uses a vacuum to...

Resin impregnation process for producing a resin-fiber composite

NASA Technical Reports Server (NTRS)

Palmer, Raymond J. (Inventor); Moore, William E. (Inventor)

1994-01-01

Process for vacuum impregnation of a dry fiber reinforcement with a curable resin to produce a resin-fiber composite, by drawing a vacuum to permit flow of curable liquid resin into and through a fiber reinforcement to impregnate same and curing the resin-impregnated fiber reinforcement at a sufficient temperature and pressure to effect final curing. Both vacuum and positive pressure, e.g. autoclave pressure, are applied to the dry fiber reinforcement prior to application of heat and prior to any resin flow to compact the dry fiber reinforcement, and produce a resin-fiber composite of reduced weight, thickness and resin content, and improved mechanical properties. Preferably both a vacuum and positive pressure, e.g. autoclave pressure, are also applied during final curing.

Fast MRI-guided vacuum-assisted breast biopsy: initial experience.

PubMed

Liberman, Laura; Morris, Elizabeth A; Dershaw, D David; Thornton, Cynthia M; Van Zee, Kimberly J; Tan, Lee K

2003-11-01

The purpose of this study was to evaluate a new method for performing MRI-guided vacuum-assisted breast biopsy in a study of lesions that had subsequent surgical excision. SUBJECTS AND METHODS. Twenty women scheduled for MRI-guided needle localization and surgical biopsy were prospectively entered in the study. MRI-guided biopsy was performed with a vacuum-assisted probe, followed by placement of a localizing clip, and then needle localization for surgical excision. Vacuum-assisted biopsy and surgical histology were correlated. Vacuum-assisted biopsy was successfully performed in 19 (95%) of the 20 women. The median size of 27 MRI-detected lesions that had biopsy was 1.0 cm (range, 0.4-6.4 cm). Cancer was present in eight (30%) of 27 lesions and in six (32%) of 19 women; among these eight cancers, five were infiltrating and three were ductal carcinoma in situ (DCIS). Among these 27 lesions, histology was benign at vacuum-assisted biopsy and at surgery in 19 (70%), cancer at vacuum-assisted biopsy in six (22%), atypical ductal hyperplasia at vacuum-assisted biopsy and DCIS at surgery in one (4%), and benign at vacuum-assisted biopsy with surgery showing microscopic DCIS that was occult at MRI in one (4%). The median time to perform vacuum-assisted biopsy of a single lesion was 35 min (mean, 35 min; range, 24-48 min). Placement of a localizing clip, attempted in 26 lesions, was successful in 25 (96%) of 26, and the clip was retrieved on specimen radiography in 22 (96%) of 23. One complication occurred: a hematoma that resolved with compression. MRI-guided vacuum-assisted biopsy is a fast, safe, and accurate alternative to surgical biopsy for breast lesions detected on MRI.

Vacuum-jacketed transfer line installation technique

NASA Technical Reports Server (NTRS)

Bowers, W. M.

1968-01-01

Rolling-type spacers in the form of steel balls retained in appropriate sleeves affixed at intervals to the exterior of the transfer line facilitate the installation of a vacuum-jacketed line. They act as standoffs to position the transfer line concentrically within the vacuum jacket line.

PETI-298 Prepared by Microwave Synthesis: Neat Resin and Composite Properties

NASA Technical Reports Server (NTRS)

Smith, Joseph G.; Connell, John W.; Li, Chao-Jun; Wu, Wei; Criss, Jim M., Jr.

2004-01-01

PETI-298 is a high temperature/high performance matrix resin that is processable into composites by resin transfer molding (RTM), resin infusion and vacuum assisted RTM techniques. It is typically synthesized in a polar aprotic solvent from the reaction of an aromatic anhydride and a combination of diamines and endcapped with phenylethynylphthalic anhydride. Microwave synthesis of PETI-298 was investigated as a means to eliminate solvent and decrease reaction time. The monomers were manually mixed and placed in a microwave oven for various times to determine optimum reaction conditions. The synthetic process was subsequently scaled-up to 330g. Three batches were synthesized and combined to give 1 kg of material that was characterized for thermal and rheological properties and compared to PETI-298 prepared by the classic solution based synthetic method. The microwave synthesized PETI-298 was subsequently used to fabricate flat laminates on T650 carbon fabric by RTM. The composite panels were analyzed and mechanical properties determined and compared with those fabricated from PETI-298 prepared by the classic solution method. The microwave synthesis process and characterization of neat resin and carbon fiber reinforced composites fabricated by RTM will be presented. KEY WORDS: Resin Transfer Molding, High Temperature Polymers, Phenylethynyl Terminated Imides, Microwave Synthesis

The benefits of using a vacuum-assisted socket system to improve balance and gait in elderly transtibial amputees.

PubMed

Samitier, C Beatriz; Guirao, Lluis; Costea, Maria; Camós, Josep M; Pleguezuelos, Eulogio

2016-02-01

Lower limb amputation leads to impaired balance, ambulation, and transfers. Proper fit of the prosthesis is a determining factor for successful ambulation. Vacuum-assisted socket systems extract air from the socket, which decreases pistoning and probability of soft-tissue injuries and increases proprioception and socket comfort. To investigate the effect of vacuum-assisted socket system on transtibial amputees' performance-based and perceived balance, transfers, and gait. Quasi-experimental before-and-after study. Subjects were initially assessed using their prosthesis with the regular socket and re-evaluated 4 weeks after fitting including the vacuum-assisted socket system. We evaluated the mobility grade using Medicare Functional Classification Level, Berg Balance Scale, Four Square Step Test, Timed Up and Go Test, the 6-Min Walk Test, the Locomotor Capabilities Index, Satisfaction with Prosthesis (SAT-PRO questionnaire), and Houghton Scale. A total of 16 unilateral transtibial dysvascular amputees, mean age 65.12 (standard deviation = 10.15) years. Using the vacuum-assisted socket system, the patients significantly improved in balance, gait, and transfers: scores of the Berg Balance Scale increased from 45.75 (standard deviation = 6.91) to 49.06 (standard deviation = 5.62) (p < 0.01), Four Square Step Test decreased from 18.18 (standard deviation = 3.84) s to 14.97 (3.9) s (p < 0.01), Timed Up and Go Test decreased from 14.3 (standard deviation = 3.29) s to 11.56 (2.46) s (p < 0.01). The distance walked in the 6-Min Walk Test increased from 288.53 (standard deviation = 59.57) m to 321.38 (standard deviation = 72.81) m (p < 0.01). Vacuum-assisted socket systems are useful for improving balance, gait, and transfers in over-50-year-old dysvascular transtibial amputees. This study gives more insight into the use of vacuum-assisted socket systems to improve elderly transtibial dysvascular amputees

Vacuum transfer system increases sugar maple sap yield

Treesearch

Russell S. Walters

1978-01-01

Yields of sugar maple sap collected from three plastic pipeline systems by gravity, vacuum pump, and a vacuum pump with a transfer tank were compared during 2 years in northern Vermont. The transfer system yielded 27 percent more sap one year and 17 percent more the next year. Higher vacuum levels at the tapholes were observed in the transfer system.

The effect of woven roving fiberglass total layers on resin infusion time in vacuum infusion

NASA Astrophysics Data System (ADS)

Saputra, A. H.; Ibrahim, R. H.

2018-04-01

Composite material consists of reinforcement materials and resin as a matrix. Vacuum infusion isone of composite material manufacturing process. This process is to minimize the air cavity on composite material. The composite material will have good mechanical properties. There is a problem in vacuum infusion related to resin gelling time that must be considered. In this study, the area as well as the reinforcement layers are variated. Unsaturated polyester was used as resin and woven roving fiberglass was used as reinforcement. This study was obtained that resin infusion time data for woven roving, 15x20 cm of size, in two until six layers are 55 seconds to 78 seconds; whereas, the infusion times for 15x25 cm of size,in two until six layers are 119 seconds to 235 seconds; whereas the infusion time for 15x35 cm of size, in two until six layers are 181 seconds to 303 seconds. By data processing, the maximum fiber area that resin still can flow, for 6 layers, is 0,4391 m2 (or 15 cm x 2.92m). Maximum fiber total layers for the specimen with 15x20cm2, 15x25cm2 and 15x35 cm2 of areaare 147, 145 and 125 layers respectively.

Low Melt Viscosity Resins for Resin Transfer Molding

NASA Technical Reports Server (NTRS)

Harris, Frank W.

2002-01-01

In recent years, resin transfer molding (RTM) has become one of the methods of choice for high performance composites. Its cost effectiveness and ease of fabrication are major advantages of RTM. RTM process usually requires resins with very low melt viscosity (less than 10 Poise). The optimum RTM resins also need to display high thennal-oxidative stability, high glass transition temperature (T(sub g)), and good toughness. The traditional PMR-type polyimides (e.g. PMR-15) do not fit this requirement, because the viscosities are too high and the nadic endcap cures too fast. High T(sub g), low-melt viscosity resins are highly desirable for aerospace applications and NASA s Reusable Launch Vehicle (RLV) program. The objective of this work is to prepare low-melt viscosity polyimide resins for RTM or resin film infusion (RFI) processes. The approach involves the synthesis of phenylethynyl-terminated imide oligomers. These materials have been designed to minimize their melt viscosity so that they can be readily processed. During the cure, the oligomers undergo both chain extension and crosslinking via the thermal polymerization of the phenylethynyl groups. The Phenylethynyl endcap is preferred over the nadic group due to its high curing temperature, which provides broader processing windows. This work involved the synthesis and polymerization of oligomers containing zig-zag backbones and twisted biphenyl structures. Some A-B type precursors which possessed both nitro and anhydride functionality, or both nitro and amine functionality, were also synthesized in order to obtain the well defined oligomers. The resulting zig-zag structured oligomers were then end-capped with 4-phenylethynylphthalic anhydride (PEPA) for further cure. The properties of these novel imide oligomers are evaluated.

Resin Permeation Through Compressed Glass Insulation for Iter Central Solenoid

NASA Astrophysics Data System (ADS)

Reed, R.; Roundy, F.; Martovetsky, N.; Miller, J.; Mann, T.

2010-04-01

Concern has been expressed about the ability of the resin system to penetrate the compressed dry glass of the turn and layer insulation during vacuum-pressure impregnation of ITER Central Solenoid (CS) modules. The stacked pancake layers of each module result in compression loads up to 9×104 kg (100 tons) on the lowest layers of each segment. The objective of this program was to assess the effects of this compressive load on resin permeation under resin-transfer conditions and with materials identical to that expected to be used in actual coil fabrication [45-50 °C, vacuum of 133 Pa (1 torr), DGEBF/anhydride epoxy resin system, E-glass satin weave, applied pressure of 125 kPa]. The experimental conditions and materials are detailed and the permeation results presented in this paper.

Curing Effects on Interfacial Adhesion between Recycled Carbon Fiber and Epoxy Resin Heated by Microwave Irradiation

PubMed Central

Shimamoto, Daisuke; Hotta, Yuji

2018-01-01

The interfacial adhesion of recycled carbon fiber (CF) reinforced epoxy composite heated by microwave (MW) irradiation were investigated by changing the curing state of the epoxy resin. The recycled CF was recovered from the composite, which was prepared by vacuum-assisted resin transfer molding, by thermal degradation at 500 or 600 °C. Thermogravimetric analysis showed that the heating at 600 °C caused rough damage to the CF surface, whereas recycled CF recovered at 500 °C have few defects. The interfacial shear strength (IFSS) between recycled CF and epoxy resin was measured by a single-fiber fragmentation test. The test specimen was heated by MW after mixing the epoxy resin with a curing agent or pre-curing, in order to investigate the curing effects on the matrix resin. The IFSSs of the MW-irradiated samples were significantly varied by the curing state of the epoxy resin and the surface condition of recycled CF, resulting that they were 99.5 to 131.7% of oven heated samples Furthermore, rheological measurements showed that the viscosity and shrinking behaviors of epoxy resin were affected based on the curing state of epoxy resin before MW irradiation. PMID:29587422

Curing Effects on Interfacial Adhesion between Recycled Carbon Fiber and Epoxy Resin Heated by Microwave Irradiation.

PubMed

Tominaga, Yuichi; Shimamoto, Daisuke; Hotta, Yuji

2018-03-26

The interfacial adhesion of recycled carbon fiber (CF) reinforced epoxy composite heated by microwave (MW) irradiation were investigated by changing the curing state of the epoxy resin. The recycled CF was recovered from the composite, which was prepared by vacuum-assisted resin transfer molding, by thermal degradation at 500 or 600 °C. Thermogravimetric analysis showed that the heating at 600 °C caused rough damage to the CF surface, whereas recycled CF recovered at 500 °C have few defects. The interfacial shear strength (IFSS) between recycled CF and epoxy resin was measured by a single-fiber fragmentation test. The test specimen was heated by MW after mixing the epoxy resin with a curing agent or pre-curing, in order to investigate the curing effects on the matrix resin. The IFSSs of the MW-irradiated samples were significantly varied by the curing state of the epoxy resin and the surface condition of recycled CF, resulting that they were 99.5 to 131.7% of oven heated samples Furthermore, rheological measurements showed that the viscosity and shrinking behaviors of epoxy resin were affected based on the curing state of epoxy resin before MW irradiation.

A pin-assisted retention technique for resin-bonded restorations.

PubMed

Miara, P; Touati, B

1992-09-01

The value of pins for auxiliary retention has been demonstrated many times. The use of pins with resin-bonded restorations allows for improved aesthetics and less tooth reduction while increasing resistance to dislodging forces. Clinical and technical procedures for resin-bonded bridges with pin-assisted retention are presented.

Vacuum-assisted drainage in cardiopulmonary bypass: advantages and disadvantages

PubMed Central

de Carvalho Filho, Élio Barreto; Marson, Fernando Augusto de Lima; da Costa, Loredana Nilkenes Gomes; Antunes, Nilson

2014-01-01

Systematic review of vacuum assisted drainage in cardiopulmonary bypass, demonstrating its advantages and disadvantages, by case reports and evidence about its effects on microcirculation. We conducted a systematic search on the period 1997-2012, in the databases PubMed, Medline, Lilacs and SciELO. Of the 70 selected articles, 26 were included in the review. Although the vacuum assisted drainage has significant potential for complications and requires appropriate technology and professionalism, prevailed in literature reviewed the concept that vacuum assisted drainage contributed in reducing the rate of transfusions, hemodilutions, better operative field, no significant increase in hemolysis, reduced complications surgical, use of lower prime and of smaller diameter cannulas. PMID:25140478

Vacuum-assisted drainage in cardiopulmonary bypass: advantages and disadvantages.

PubMed

Carvalho Filho, Elio Barreto de; Marson, Fernando Augusto de Lima; Costa, Loredana Nilkenes Gomes da; Antunes, Nilson

2014-01-01

Systematic review of vacuum assisted drainage in cardiopulmonary bypass, demonstrating its advantages and disadvantages, by case reports and evidence about its effects on microcirculation. We conducted a systematic search on the period 1997-2012, in the databases PubMed, Medline, Lilacs and SciELO. Of the 70 selected articles, 26 were included in the review. Although the vacuum assisted drainage has significant potential for complications and requires appropriate technology and professionalism, prevailed in literature reviewed the concept that vacuum assisted drainage contributed in reducing the rate of transfusions, hemodilutions, better operative field, no significant increase in hemolysis, reduced complications surgical, use of lower prime and of smaller diameter cannulas.

Co-Curing of CFRP-Steel Hybrid Joints Using the Vacuum Assisted Resin Infusion Process

NASA Astrophysics Data System (ADS)

Streitferdt, Alexander; Rudolph, Natalie; Taha, Iman

2017-10-01

This study focuses on the one-step co-curing process of carbon fiber reinforced plastics (CFRP) joined with a steel plate to form a hybrid structure. In this process CFRP laminate and bond to the metal are realized simultaneously by resin infusion, such that the same resin serves for both infusion and adhesion. For comparison, the commonly applied two-step process of adhesive bonding is studied. In this case, the CFRP laminate is fabricated in a first stage through resin infusion of Non Crimp Fabric (NCF) and joined to the steel plate in a further step through adhesive bonding. For this purpose, the commercially available epoxy-based Betamate 1620 is applied. CFRP laminates were fabricated using two different resin systems, namely the epoxy (EP)-based RTM6 and a newly developed fast curing polyurethane (PU) resin. Results show comparable mechanical performance of the PU and EP based CFRP laminates. The strength of the bond of the co-cured samples was in the same order as the samples adhesively bonded with the PU resin and the structural adhesive. The assembly adhesive with higher ductility showed a weaker performance compared to the other tests. It could be shown that the surface roughness had the highest impact on the joint performance under the investigated conditions.

Resin transfer molding of textile composites

NASA Technical Reports Server (NTRS)

Falcone, Anthony; Dursch, Harry; Nelson, Karl; Avery, William

1993-01-01

The design and manufacture of textile composite panels, tubes, and angle sections that were provided to NASA for testing and evaluation are documented. The textile preform designs and requirements were established by NASA in collaboration with Boeing and several vendors of textile reinforcements. The following four types of preform architectures were used: stitched uniweave, 2D-braids, 3D-braids, and interlock weaves. The preforms consisted primarily of Hercules AS4 carbon fiber; Shell RSL-1895 resin was introduced using a resin transfer molding process. All the finished parts were inspected using ultrasonics.

Window-assisted nanosphere lithography for vacuum micro-nano-electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Nannan; Institute of Electronic Engineering, Chinese Academy of Engineering Physics, Mianyang, 621900; Pang, Shucai

2015-04-15

Development of vacuum micro-nano-electronics is quite important for combining the advantages of vacuum tubes and solid-state devices but limited by the prevailing fabricating techniques which are expensive, time consuming and low-throughput. In this work, window-assisted nanosphere lithography (NSL) technique was proposed and enabled the low-cost and high-efficiency fabrication of nanostructures for vacuum micro-nano-electronic devices, thus allowing potential applications in many areas. As a demonstration, we fabricated high-density field emitter arrays which can be used as cold cathodes in vacuum micro-nano-electronic devices by using the window-assisted NSL technique. The details of the fabricating process have been investigated. This work provided amore » new and feasible idea for fabricating nanostructure arrays for vacuum micro-nano-electronic devices, which would spawn the development of vacuum micro-nano-electronics.« less

DGEBF epoxy blends for use in the resin impregnation of extremely large composite parts

DOE PAGES

Madhukar, M. S.; Martovetsky, N. N.

2015-01-16

Large superconducting electromagnets used in fusion reactors utilize a large amount of glass/epoxy composite for electrical insulation and mechanical and thermal strengths. Moreover, the manufacture of these magnets involves wrapping each superconducting cable bundle with dry glass cloth followed by the vacuum-assisted resin transfer molding of the entire magnet. Due to their enormous size (more than 100 tons), it requires more than 40 h for resin impregnation and the subsequent pressure cycles to ensure complete impregnation and removal of any trapped air pockets. Diglycidyl ether of bisphenol F epoxy resin cross-linked with methyltetrahydrophthalic anhydride with an accelerator has been shownmore » to be a good candidate for use in composite parts requiring long impregnation cycles. Viscosity, gel time, and glass transition temperature of four resin-blends of diglycidyl ether of bisphenol F resin system were monitored as a function of time and temperature with an objective to find the blend that provides a working window longer than 40h at low viscosity without lowering its glass transition temperature. A resin-blend in the weight ratios of resin:hardener:accelerator=100:82:0.125 is shown to provide more than 60h at low resin viscosity while maintaining the same glass transition temperature as obtained with previously used resin-blends, based on the results.« less

Management of hidradenitis suppurativa wounds with an internal vacuum-assisted closure device.

PubMed

Chen, Y Erin; Gerstle, Theodore; Verma, Kapil; Treiser, Matthew D; Kimball, Alexandra B; Orgill, Dennis P

2014-03-01

Hidradenitis suppurativa is a chronic, debilitating disease that is difficult to treat. Once medical management fails, wide local excision offers the best chance for cure. However, the resultant wound often proves too large or contaminated for immediate closure. The authors performed a retrospective chart review of hidradenitis cases managed surgically between 2005 and 2010. Data collected included patient characteristics, management method, and outcomes. Approximately half of the patients received internal vacuum-assisted closure therapy using the vacuum-assisted closure system and delayed closure and half of the patients received immediate primary closure at the time of their excision. Delayed closure consisted of closing the majority of the wound in a linear fashion following internal vacuum-assisted closure while accepting healing by means of secondary intention for small wound areas. Patients managed with internal vacuum-assisted closure had wounds on average four times larger in area than patients managed without internal vacuum-assisted closure. In both groups, all wounds were eventually closed primarily. Healing times averaged 2.2 months with internal vacuum-assisted closure and 2.7 months without. At an average follow-up time of 2.3 months, all patients with internal vacuum-assisted closure had no recurrence of their local disease. Severe hidradenitis presents a treatment challenge, as surgical excisions are often complicated by difficult closures and unsatisfactory recurrence rates. This study demonstrates that wide local excision with reasonable outcomes can be achieved using accelerated delayed primary closure. This method uses internal vacuum-assisted closure as a bridge between excision and delayed primary closure, facilitating closure without recurrence in large, heavily contaminated wounds. Therapeutic, III.

High Temperature VARTM of Phenylethynyl Terminated Imides (PETI) Resins

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Cano, Roberto J.; Britton, Sean M.; Watson, Kent A.; Jensen, Brian J.; Connell, John W.

2010-01-01

Fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications a void fraction of less than 2% is desired. In the current study, two PETI resins, LARCTM PETI-330 and LARCTM PETI-8 have been used to fabricate test specimens using HT-VARTM. The resins were infused into carbon fiber preforms at 260 C and cured between 316 C and 371 C. Modifications to the thermal cycle used in the laminate fabrication have reduced the void content significantly (typically < 3%) for carbon fiber biaxially woven fabric. Photomicrographs of the panels were taken and void contents were determined by acid digestion. For carbon fiber uniaxial fabric, void contents of less than 2% have been obtained using both PETI-8 and PETI-330. Mechanical properties of the panels were determined at both room and elevated temperatures. These include short beam shear and flexure tests. The results of this work are presented herein.

HEPA filter encapsulation

DOEpatents

Gates-Anderson, Dianne D.; Kidd, Scott D.; Bowers, John S.; Attebery, Ronald W.

2003-01-01

A low viscosity resin is delivered into a spent HEPA filter or other waste. The resin is introduced into the filter or other waste using a vacuum to assist in the mass transfer of the resin through the filter media or other waste.

Indirect resin composite restorations bonded to dentin using self-adhesive resin cements applied with an electric current-assisted method.

PubMed

Gotti, Valeria Bisinoto; Feitosa, Victor Pinheiro; Sauro, Salvatore; Correr-Sobrinho, Lourenço; Correr, Americo Bortolazzo

2014-10-01

To evaluate the effects of an electric current-assisted application on the bond strength and interfacial morphology of self-adhesive resin cements bonded to dentin. Indirect resin composite build-ups were luted to prepared dentin surfaces using two self-adhesive resin cements (RelyX Unicem and BisCem) and an ElectroBond device under 0, 20, or 40 μA electrical current. All specimens were submitted to microtensile bond strength test and to interfacial SEM analysis. The electric current-assisted application induced no change (P > 0.05) on the overall bond strength, although RelyX Unicem showed significantly higher bond strength (P < 0.05) than BisCem. Similarly, no differences were observed in terms of interfacial integrity when using the electrical current applicator.

Resin transfer molding speeds composite making

NASA Astrophysics Data System (ADS)

Valenti, Michael

1992-11-01

Fabrication resin transfer molding (RTM) composite parts for different industrial applications is discussed. These applications include composite aerospace parts, sports car components, and high performance sporting equipment. It is pointed out that RTM parts are lighter than metals and can be formulated to have superior durability. But like all composite parts, they are expensive and are made in limited runs.

Heat transfer in a liquid helium cooled vacuum tube following sudden vacuum loss

NASA Astrophysics Data System (ADS)

Dhuley, R. C.; Van Sciver, S. W.

2015-12-01

Condensation of nitrogen gas rapidly flowing into a liquid helium (LHe) cooled vacuum tube is studied. This study aims to examine the heat transfer in geometries such as the superconducting RF cavity string of a particle accelerator following a sudden loss of vacuum to atmosphere. In a simplified experiment, the flow is generated by quickly venting a large reservoir of nitrogen gas to a straight long vacuum tube immersed in LHe. Normal LHe (LHe I) and superfluid He II are used in separate experiments. The rate of condensation heat transfer is determined from the temperature of the tube measured at several locations along the gas flow. Instantaneous heat deposition rates in excess of 200 kW/m2 result from condensation of the flowing gas. The gas flow is then arrested in its path to pressurize the tube to atmosphere and estimate the heat transfer rate to LHe. A steady LHe I heat load of ≈25 kW/m2 is obtained in this scenario. Observations from the He II experiment are briefly discussed. An upper bound for the LHe I heat load is derived based on the thermodynamics of phase change of nitrogen.

Influence of temperature on styrene emission from a vinyl ester resin thermoset composite material.

PubMed

Crawford, Shaun; Lungu, Claudiu T

2011-08-15

Composite materials made with vinyl ester resins are lighter, stronger and corrosion resistant compared to most metals, and are increasingly being used as building materials and in public transportation. Styrene monomer is used as both a diluent and strengthener in the production of vinyl ester resin (VER) composites. Some researchers contend that free styrene in VER composites is available to diffuse out of the material into air, perhaps leading to adverse health effects via inhalation exposures in humans, yet there is no known data on styrene emissions from these materials in the literature. In this study, a typical VER composite made with resin containing 38% by weight styrene, reinforced with E-glass fiber and formed using a vacuum assisted resin transfer method was characterized for styrene emissions by environmental test chamber (ETC) methodology. Styrene concentrations in the ETC were measured over a temperature range of 10 to 50 °C. Initial evaporative styrene emissions increase with increasing temperature. There is a nearly linear relationship in the total mass of styrene emitted and emission factor as emissions increase with increasing temperature. Styrene emission factors appear to vary for different materials, which could indicate more complex processes or the influence of material physical properties on emission rates. These results can be used to validate and improve mass transfer emission models for the prediction of volatile organic compound concentrations in indoor environments. Published by Elsevier B.V.

High Temperature Transfer Molding Resins

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

2000-01-01

High temperature resins containing phenylethynyl groups that are processable by transfer molding have been prepared. These phenylethynyl containing oligomers were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynlphthalic anhydride in glacial acetic acid to form a mixture of imide compounds in one step. This synthetic approach is advantageous since the products are a mixture of compounds and consequently exhibit a relatively low melting temperature. In addition, these materials exhibit low melt viscosities which are stable for several hours at 210-275 C, and since the thermal reaction of the phenylethynyl group does not occur to any appreciable extent at temperatures below 300 C, these materials have a broad processing window. Upon thermal cure at approximately 300-350 C, the phenylethynyl groups react to provide a crosslinked resin system. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

Vacuum infusion method for woven carbon/Kevlar reinforced hybrid composite

NASA Astrophysics Data System (ADS)

Hashim, N.; Majid, D. L.; Uda, N.; Zahari, R.; Yidris, N.

2017-12-01

The vacuum assisted resin transfer moulding (VaRTM) or Vacuum Infusion (VI) is one of the fabrication methods used for composite materials. Compared to other methods, this process costs lower than using prepregs because it does not need to use the autoclave to cure. Moreover, composites fabricated using this VI method exhibit superior mechanical properties than those made through hand layup process. In this study, the VI method is used in fabricating woven carbon/Kevlar fibre cloth with epoxy matrix. This paper reports the detailed methods on fabricating the hybrid composite using VI process and several precautions that need to be taken to avoid any damage to the properties of the composite material. The result highlights that the successfully fabricated composite has approximately 60% of fibres weight fraction. Since the composites produced by the VI process have a higher fibre percentage, this process should be considered for composites used in applications that are susceptible to the conditions where the fibres need to be the dominant element such as in tension loading.

Emergent Embolization of Arterial Bleeding after Vacuum-Assisted Breast Biopsy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischman, Aaron M., E-mail: aaron.fischman@mountsinai.org; Epelboym, Yan, E-mail: yan.epelboym@mssm.edu; Siegelbaum, Robert H., E-mail: rhsiegelbaum@gmail.com

2012-02-15

Vacuum-assisted core breast biopsy has become important in evaluating patients with suspicious breast lesions. It has proven to be a relatively safe procedure that in rare cases can result in vascular complications. These are the first reported cases of transcatheter embolization of uncontrolled breast hemorrhage after vacuum-assisted breast biopsy. With increased use of biopsy and larger-gauge devices, breast imaging groups may consider embolotherapy as a safe alternative for treatment of hemorrhage in a select group of patients.

Infiltration/cure modeling of resin transfer molded composite materials using advanced fiber architectures

NASA Technical Reports Server (NTRS)

Loos, Alfred C.; Weideman, Mark H.; Long, Edward R., Jr.; Kranbuehl, David E.; Kinsley, Philip J.; Hart, Sean M.

1991-01-01

A model was developed which can be used to simulate infiltration and cure of textile composites by resin transfer molding. Fabric preforms were resin infiltrated and cured using model generated optimized one-step infiltration/cure protocols. Frequency dependent electromagnetic sensing (FDEMS) was used to monitor in situ resin infiltration and cure during processing. FDEMS measurements of infiltration time, resin viscosity, and resin degree of cure agreed well with values predicted by the simulation model. Textile composites fabricated using a one-step infiltration/cure procedure were uniformly resin impregnated and void free. Fiber volume fraction measurements by the resin digestion method compared well with values predicted using the model.

Influence of the vacuum resin process, on the ballistic behaviour of lightweight armouring solutions

NASA Astrophysics Data System (ADS)

Lefebvre, M.; Boussu, F.; Coutellier, D.; Vallee, D.

2012-08-01

classical vacuum resin infusion; the second used a press in order to reach a resin ratio near to the existing protection. The existing protection is a prepreg structure with a fibre content of 88%. It has been revealed that a resin rate less than 35% inside the warp interlocks composite material leads to have equivalent ballistics performances than existing protection.

Vacuum-assisted closure therapy in the management of lung abscess.

PubMed

Sziklavari, Zsolt; Ried, Michael; Hofmann, Hans-Stefan

2014-09-06

Despite significant advances in the treatment of thoracic infections, complex lung abscess remains a problem in modern thoracic surgery. We describe the novel application of vacuum-assisted closure for the treatment of a lung abscess. The technical details and preliminary results are reported. After the initial failed conservative treatment of an abscess, minimally invasive surgical intervention was performed with vacuum-assisted closure. The vacuum sponges were inserted in the abscess cavity at the most proximal point to the pleural surface. The intercostal space of the chest wall above the entering place was secured by a soft tissue retractor. The level of suction was initially set to 100 mm Hg, with a maximum suction of 125 mm Hg. The sponge was changed once on the 3rd postoperative day. The abscess cavity was rapidly cleaned and decreased in size. The mini-thoracotomy could be closed on the 9th postoperative day. Closure of the cavity was simple, without any short- or long-term treatment failure. This technique reduced the trauma associated with the procedure. The patient was discharged on the 11th postoperative day. Vacuum-assisted closure systems should be considered for widespread use as an alternative option for the treatment of complicated pulmonary abscess in elderly, debilitated, immunocompromised patients after failed conservative treatment.

Transfer orbit stage mechanisms thermal vacuum test

NASA Technical Reports Server (NTRS)

Oleary, Scott T.

1990-01-01

A systems level mechanisms test was conducted on the Orbital Sciences Corp.'s Transfer Orbit Stage (TOS). The TOS is a unique partially reusable transfer vehicle which will boost a satellite into its operational orbit from the Space Shuttle's cargo bay. The mechanical cradle and tilt assemblies will return to earth with the Space Shuttle while the Solid Rocket Motor (SRM) and avionics package are expended. A mechanisms test was performed on the forward cradle and aft tilting assemblies of the TOS under thermal vacuum conditions. Actuating these assemblies under a 1 g environment and thermal vacuum conditions proved to be a complex task. Pneumatic test fixturing was used to lift the forward cradle, and tilt the SRM, and avionics package. Clinometers, linear voltage displacement transducers, and load cells were used in the thermal vacuum chamber to measure the performance and characteristics of the TOS mechanism assembly. Incorporation of the instrumentation and pneumatic system into the test setup was not routine since pneumatic actuation of flight hardware had not been previously performed in the facility. The methods used are presented along with the problems experienced during the design, setup and test phases.

Homogenization-assisted cavitation hybrid rotation extraction and macroporous resin enrichment of dihydroquercetin from Larix gmelinii.

PubMed

Xia, Yu; Wang, Yinhang; Li, Wei; Ma, Chunhui; Liu, Shouxin

2017-12-01

Cavitation hybrid rotation, which was and is still looked upon as an unavoidable nuisance in the flow systems, for extraction processing intensification of active chemical compounds from natural products. In this study, a homogenization-assisted cavitation hybrid rotation extraction method was applied to extract dihydroquercetin (DHQ) from larch (Larix gmelinii) wood root. The extraction parameters were optimized in single factor experiments with the DHQ extraction yields as the response values. The optimum conditions were as follows: number of extractions, three; ethanol volume fraction for the extraction, 60%; liquid-solid ratio for homogenization, 10mL/g; homogenization time, 8min; liquid-solid ratio for cavitation extraction, 9mL/g, and cavitation extraction time, 35min. Under these conditions, the DHQ content in extract was 4.50±0.02mg/g, and the extraction efficiency was higher than those of traditional techniques. Cavitation can be effectively used to improve the extraction rate by increasing the mass transfer rates and possible rupture of cell wall due to formation of microcavities leading to higher product yields with reduced processing time and solvent consumption. After the extraction process, macroporous resin column chromatography was used to concentrate and purify the DHQ. Three resins were selected from fifteen macroporous resins for further investigation of their performance. Among these resins, AB-8 resin exhibited relatively better adsorption capacities and desorption ratios for DHQ. The ethanol volume fraction of the solutions for sample loading and desorption, and flow rates for loading and desorption were optimized for the macroporous resin column chromatography. Copyright © 2017 Elsevier B.V. All rights reserved.

Risk factors for anal sphincter tears in vacuum-assisted delivery.

PubMed

Ryman, P; Ahlberg, M; Ekéus, C

2015-10-01

The aim of the present study was to describe the prevalence of anal sphincter tears (AST) in relation to obstetric management and technique during vacuum extraction deliveries (VE) (re: indications, the station of the fetal head at application of the cup, number of tractions, the length for the extraction, cup detachments, pain relief, episiotomy, fetal presentation, and experience of the operator) as well as maternal and infant anthropometrics. Descriptive study. Data on six hundred vacuum extraction deliveries were consecutively collected from six different delivery units in Sweden. Each unit contributed with data on 100 deliveries. The final study population included 596 women who delivered by vacuum extraction. There was no correlation between the management of the vacuum extraction and risk for anal sphincter tear. Women from Africa had nearly a fourfold risk for anal sphincter tear during vacuum-assisted delivery compared with Swedish-born women (OR 3.82 CI 1.47-9.89). Compared with infants with birth weight less than 4000 g, birth weight above 4000 g was associated with increased risk of AST (OR 1.87 CI 1.06-3.28). In this study, the obstetric management in VE-assisted deliveries did not impact the risk of AST. Copyright © 2015 Elsevier B.V. All rights reserved.

The cost effectiveness of vacuum-assisted versus core-needle versus surgical biopsy of breast lesions.

PubMed

Fernández-García, P; Marco-Doménech, S F; Lizán-Tudela, L; Ibáñez-Gual, M V; Navarro-Ballester, A; Casanovas-Feliu, E

To determine the cost effectiveness of breast biopsy by 9G vacuum-assisted guided by vertical stereotaxy or ultrasonography in comparison with breast biopsy by 14G core-needle biopsy and surgical biopsy. We analyzed a total of 997 biopsies (181 vacuum-assisted, 626 core, and 190 surgical biopsies). We calculated the total costs (indirect and direct) of the three types of biopsy. We did not calculate intangible costs. We measured the percentage of correct diagnoses obtained with each technique. To identify the most cost-effective option, we calculated the mean ratios for the three types of biopsies. Total costs were €225.09 for core biopsy, €638.90 for vacuum-assisted biopsy, and €1780.01 for surgical biopsy. The overall percentage of correct diagnoses was 91.81% for core biopsy, 94.03% for vacuum-assisted biopsy, and 100% for surgical biopsy; however, these differences did not reach statistical significance (p=0.3485). For microcalcifications, the percentage of correct diagnoses was 50% for core biopsy and 96.77% for vacuum-assisted biopsy (p<0.0001). For nodules, there were no significant differences among techniques. The mean cost-effectiveness ratio considering all lesions was 2.45 for core biopsy, 6.79 for vacuum-assisted biopsy, and 17.80 for surgical biopsy. Core biopsy was the dominant option for the diagnosis of suspicious breast lesions in general. However, in cases with microcalcifications, the low percentage of correct diagnoses achieved by core biopsy (50%) advises against its use in this context, where vacuum-assisted biopsy would be the technique of choice because it is more cost-effective than surgical biopsy, the other technique indicated for biopsying microcalcifications. Copyright © 2016 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

High Temperature VARTM of Phenylethynyl Terminated Imides

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Watson, Kent A.; Cano, Roberto J.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.

2009-01-01

LaRC phenylethynyl terminated imide (PETI) resins were processed into composites using high temperature vacuum assisted resin transfer molding (VARTM). Although initial runs yielded composites with high void content, process modifications reduced voids to <3%. Photomicrographs were taken and void contents and T(sub g)s of the panels were determined.

Resection of giant right atrial lymphoma using vacuum-assisted cardiopulmonary bypass without snaring the inferior vena cava.

PubMed

Shin, Hankei; Mori, Mitsuharu; Matayoshi, Toru; Suzuki, Ryo; Yozu, Ryohei

2004-08-01

A 53-year-old man sustained hemodynamic collapse due to a huge right atrial tumor and was transferred to our hospital and underwent a life-saving emergency operation. The tumor arose from the inferolateral wall of the right atrium, occupying almost the whole right atrial cavity and obstructing not only the inflow of the right ventricle but also the orifice of the inferior vena cava. Venous cannulation via the right atrial wall and placing a snare around the inferior vena cava were impossible. With a cardiopulmonary bypass using vacuum-assisted venous drainage, the tumor was successfully resected and the tricuspid valve was replaced with a bioprosthetic valve without snaring the inferior vena cava. Postoperative histological examination demonstrated the tumor to be a large B-cell non-Hodgkin type malignant lymphoma. When the tumor is large and it is difficult to establish total cardiopulmonary bypass, the vacuum-assisted cardiopulmonary bypass is a useful option. This can achieve a bloodless operative field and is not blocked by the incoming air, due to the venous drainage being continually pressure-regulated.

21. Engine identified as a 'single cylinder vacuum assist engine ...

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

21. Engine identified as a 'single cylinder vacuum assist engine for Tod tandem compound engine' showing compressor. - Carnegie Steel-Ohio Works, Steam Engines, 912 Salt Springs Road, Youngstown, Mahoning County, OH

An effective vacuum assisted extraction method for the optimization of labdane diterpenoids from Andrographis paniculata by response surface methodology.

PubMed

Wang, Ya-Qi; Wu, Zhen-Feng; Ke, Gang; Yang, Ming

2014-12-31

An effective vacuum assisted extraction (VAE) technique was proposed for the first time and applied to extract bioactive components from Andrographis paniculata. The process was carefully optimized by response surface methodology (RSM). Under the optimized experimental conditions, the best results were obtained using a boiling temperature of 65 °C, 50% ethanol concentration, 16 min of extraction time, one extraction cycles and a 12:1 liquid-solid ratio. Compared with conventional ultrasonic assisted extraction and heat reflux extraction, the VAE technique gave shorter extraction times and remarkable higher extraction efficiency, which indicated that a certain degree of vacuum gave the solvent a better penetration of the solvent into the pores and between the matrix particles, and enhanced the process of mass transfer. The present results demonstrated that VAE is an efficient, simple and fast method for extracting bioactive components from A. paniculata, which shows great potential for becoming an alternative technique for industrial scale-up applications.

20. Engine identified as a 'single cylinder vacuum assist engine ...

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

20. Engine identified as a 'single cylinder vacuum assist engine for the Tod tandem compound engine' showing crank end. - Carnegie Steel-Ohio Works, Steam Engines, 912 Salt Springs Road, Youngstown, Mahoning County, OH

19. Engine identified as a single cylinder vacuum assist engine ...

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

19. Engine identified as a single cylinder vacuum assist engine for the Filer and Stowell 15-inch continuous mill. - Carnegie Steel-Ohio Works, Steam Engines, 912 Salt Springs Road, Youngstown, Mahoning County, OH

Evaluation of shrinkage polymerization and temperature of different acrylic resins used to splinting transfer copings in indirect impression technique

NASA Astrophysics Data System (ADS)

Franco, Ana Paula G. O.; Karam, Leandro Z.; Galvão, José R.; Kalinowski, Hypolito J.

2015-09-01

The aim of the present study was evaluate the shrinkage polymerization and temperature of different acrylic resins used to splinting transfer copings in indirect impression technique. Two implants were placed in an artificial bone, with the two transfer copings joined with dental floss and acrylic resins; two dental resins are used. Measurements of deformation and temperature were performed with Fiber Braggs grating sensor for 17 minutes. The results revealed that one type of resin shows greater values of polymerization shrinkage than the other. Pattern resins did not present lower values of shrinkage, as usually reported by the manufacturer.

High Temperature Transfer Molding Resins Based on 2,3,3',4'-Biphenyltetracarboxylic Dianhydride

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Yokota, R.; Criss, J. M.

2002-01-01

As part of an ongoing effort to develop materials for resin transfer molding (RTM) processes to fabricate high performance/high temperature composite structures, phenylethynyl containing imides have been under investigation. New phenylethynyl containing imide compositions were prepared using 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) and evaluated for cured glass transition temperature (Tg), melt flow behavior, and for processability into flat composite panels via RTM. The a-BPDA imparts a unique combination of properties that are desirable for high temperature transfer molding resins. In comparison to its symmetrical counterpart (i.e. 3,3',4,4'-biphenyltetracarboxylic dianhydride), a-BPDA affords oligomers with lower melt viscosities and when cured, higher Tgs. Several candidates exhibited the appropriate combination of properties such as a low and stable melt viscosity required for RTM processes, high cured Tg, and moderate toughness. The chemistry, physical, and composite properties of select resins will be discussed.

[Vacuum-assisted therapy for various wound types including diabetic foot ulcer].

PubMed

Farah, Raymond; Gantus, Maher; Kogan, Leonid

2011-03-01

Vacuum is a noninvasive system that creates a localized controlled negative pressure environment. In this study, vacuum was provided by the V.A.C. Therapy system, which promotes wound healing by delayed primary or secondary intention through creating a moist wound environment, preparing the wound bed for closure, reducing edema, and promoting formation and perfusion of granulation tissue. Vacuum-assisted closure therapy is indicated for use in all care settings and for a variety of wound types including diabetic foot ulcers. The purpose of this study was to evaluate safety and clinical efficacy of negative pressure wound therapy (NPWT) compared with advanced moist wound therapy and standard treatment to treat foot ulcers in diabetic patients. This trial enrolled 43 patients; most of them were diabetic patients at any age with various skin ulcers and diabetic foot. These patients were divided into two groups, 17 patients were treated with vacuum and the 26 patients in the control group were treated with standard therapy including debridement. A greater proportion of foot and skin ulcers achieved complete ulcer closure with vacuum-assisted therapy p<0.001 compared with the standard therapy. Vacuum therapy significantly decreased the duration and frequency of admission p=0.032 and decreased the rate of amputation p<0.001. Results of our trial support other studies and demonstrate that vacuum is as safe as and more efficacious than standard therapy in the treatment of diabetic foot ulcers. A significantly greater number of patients achieved complete ulcer closure and granulation tissue formation with this therapy. The study group showed a significant reduction in the median time needed to heal ulcers, reduction of the number of admissions and amputation frequency.

Resin transfer molding of textile preforms for aircraft structural applications

NASA Technical Reports Server (NTRS)

Hasko, Gregory H.; Dexter, H. Benson; Weideman, Mark H.

1992-01-01

The NASA LaRC is conducting and supporting research to develop cost-effective fabrication methods that are applicable to primary composite aircraft structures. One of the most promising fabrication methods that has evolved is resin transfer molding (RTM) of dry textile material forms. RTM has been used for many years for secondary structures, but has received increased emphasis because it is an excellent method for applying resin to damage-tolerant textile preforms at low cost. Textile preforms based on processes such as weaving, braiding, knitting, stitching, and combinations of these have been shown to offer significant improvements in damage tolerance compared to laminated tape composites. The use of low-cost resins combined with textile preforms could provide a major breakthrough in achieving cost-effective composite aircraft structures. RTM uses resin in its lowest cost form, and storage and spoilage costs are minimal. Near net shape textile preforms are expected to be cost-effective because automated machines can be used to produce the preforms, post-cure operations such as machining and fastening are minimized, and material scrap rate may be reduced in comparison with traditional prepreg molding. The purpose of this paper is to discuss experimental and analytical techniques that are under development at NASA Langley to aid the engineer in developing RTM processes for airframe structural elements. Included are experimental techniques to characterize preform and resin behavior and analytical methods that were developed to predict resin flow and cure kinetics.

Modeling of process-induced residual stresses and resin flow behavior in resin transfer molded composites with woven fiber mats

NASA Astrophysics Data System (ADS)

Golestanian, Hossein

This research focuses on modeling Resin Transfer Molding process for manufacture of composite parts with woven fiber mats. Models are developed to determine cure dependent stiffness matrices for composites manufactured with two types of woven fiber mats. Five-harness carbon and eight-harness fiberglass mats with EPON 826 resin composites are considered. The models presented here take into account important material/process parameters with emphasis on; (1) The effects of cure-dependent resin mechanical properties, (2) Fiber undulation due to the weave of the fiber fill and warp bundles, and (3) Resin interaction with the fiber bundles at a microscopic scale. Cure-dependent mechanical properties were then used in numerical models to determine residual stresses and deformation in the composite parts. The complete cure cycle was modeled in these analyses. Also the cool down stage after the composite cure was analyzed. The effect of 5% resin shrinkage on residual stresses and deformations was also investigated. In the second part of the study, Finite Element models were developed to simulate mold filling in RTM processes. Resin flow in the fiber mats was modeled as flow through porous media. Physical models were also developed to investigate resin flow behavior into molds of rectangular and irregular shapes. Silicone fluids of 50 and 100 centistoke viscosities as well as EPON 826 epoxy resin were used in the mold filling experiments. The reinforcements consisted of several layers of woven fiberglass and carbon fiber mats. The effects of injection pressure, fluid viscosity, type of reinforcement, and mold geometry on mold filling times were investigated. Fiber mat permeabilities were determined experimentally for both types of reinforcements. Comparison of experimental and numerical resin front positions indicated the importance of edge effects in resin flow behavior in small cavities. The resin front positions agreed well for the rectangular mold geometry.

Resin transfer molding for advanced composite primary aircraft structures

NASA Technical Reports Server (NTRS)

Markus, Alan; Palmer, Ray

1991-01-01

Resin Transfer Molding (RTM) has been identified by Douglas Aircraft Company (DAC) and industry to be one of the promising processes being developed today which can break the cost barrier of implementing composite primary structures into a commercial aircraft production environment. The RTM process developments and scale-up plans Douglas Aircrart will be conducting under the NASA ACT contract are discussed.

Use of the 2-chlorotrityl chloride resin for microwave-assisted solid phase peptide synthesis.

PubMed

Ieronymaki, Matthaia; Androutsou, Maria Eleni; Pantelia, Anna; Friligou, Irene; Crisp, Molly; High, Kirsty; Penkman, Kirsty; Gatos, Dimitrios; Tselios, Theodore

2015-09-01

A fast and efficient microwave (MW)-assisted solid-phase peptide synthesis protocol using the 2-chlorotrityl chloride resin and the Fmoc/tBu methodology, has been developed. The established protocol combines the advantages of MW irradiation and the acid labile 2-chlorotrityl chloride resin. The effect of temperature during the MW irradiation, the degree of resin substitution during the coupling of the first amino acids and the rate of racemization for each amino acid were evaluated. The suggested solid phase methodology is applicable for orthogonal peptide synthesis and for the synthesis of cyclic peptides. © 2015 Wiley Periodicals, Inc.

VARTM Model Development and Verification

NASA Technical Reports Server (NTRS)

Cano, Roberto J. (Technical Monitor); Dowling, Norman E.

2004-01-01

In this investigation, a comprehensive Vacuum Assisted Resin Transfer Molding (VARTM) process simulation model was developed and verified. The model incorporates resin flow through the preform, compaction and relaxation of the preform, and viscosity and cure kinetics of the resin. The computer model can be used to analyze the resin flow details, track the thickness change of the preform, predict the total infiltration time and final fiber volume fraction of the parts, and determine whether the resin could completely infiltrate and uniformly wet out the preform.

Evaluation of a Prototype Hybrid Vacuum Pump to Provide Vacuum-Assisted Suspension for Above-Knee Prostheses

PubMed Central

Major, Matthew J.; Caldwell, Ryan; Fatone, Stefania

2015-01-01

Vacuum-assisted suspension (VAS) of prosthetic sockets utilizes a pump to evacuate air from between the prosthetic liner and socket, and are available as mechanical or electric systems. This technical note describes a hybrid pump that benefits from the advantages of mechanical and electric systems, and evaluates a prototype as proof-of-concept. Cyclical bench testing of the hybrid pump mechanical system was performed using a materials testing system to assess the relationship between compression cycles and vacuum pressure. Phase 1 in vivo testing of the hybrid pump was performed by an able-bodied individual using prosthesis simulator boots walking on a treadmill, and phase 2 involved an above-knee prosthesis user walking with the hybrid pump and a commercial electric pump for comparison. Bench testing of 300 compression cycles produced a maximum vacuum of 24 in-Hg. In vivo testing demonstrated that the hybrid pump continued to pull vacuum during walking, and as opposed to the commercial electric pump, did not require reactivation of the electric system during phase 2 testing. The novelty of the hybrid pump is that while the electric system provides rapid, initial vacuum suspension, the mechanical system provides continuous air evacuation while walking to maintain suspension without reactivation of the electric system, thereby allowing battery power to be reserved for monitoring vacuum levels. PMID:27462383

Surface Flashover on Epoxy-Resin Printed Circuit Boards in Vacuum under Electron Irradiation

NASA Astrophysics Data System (ADS)

Fujii, Haruhisa; Hasegawa, Taketoshi; Osuga, Hiroyuki; Matsui, Katsuaki

This paper deals with the surface flashover characteristics of dielectric material in vacuum during electron beam irradiation in order to design adequately the conductive patterns on printed circuit boards used inside a spacecraft. The dielectric material, glass-fiber reinforced epoxy resin, and the electrodes printed on it were irradiated with electrons of the energy of 3-10 keV. DC high voltage was applied between the two electrodes during electron irradiation. The voltage was increased stepwise until the surface flashover occurred on the dielectric material. We obtained the results that the surface flashover voltage increased with the insulation distance between the electrodes but electron irradiation made the flashover voltage lower. The flashover voltage characteristics were obtained as parameters of the electrode distance and the energy of the electron beam.

Nano-Composites: Relationships Between Nano-Structure and Mechanical Properties: Phase II

DTIC Science & Technology

2006-01-01

was pre-reacted with the DEGBA resin to give a 40 wt.% CTBN -epoxy adduct: ‘Albipox 1000’ from Hanse Chemie, Geesthacht, Germany. The curing agent was...not lead to a decrease in the modulus of the composite. Nor does it lead to a significant increase in the viscosity of the epoxy resin , which would...preclude the use of low-cost manufacturing routes, such as a vacuum-assisted resin -transfer moulding (VARTM) process. Keywords Epoxy

Verification of a three-dimensional resin transfer molding process simulation model

NASA Technical Reports Server (NTRS)

Fingerson, John C.; Loos, Alfred C.; Dexter, H. Benson

1995-01-01

Experimental evidence was obtained to complete the verification of the parameters needed for input to a three-dimensional finite element model simulating the resin flow and cure through an orthotropic fabric preform. The material characterizations completed include resin kinetics and viscosity models, as well as preform permeability and compaction models. The steady-state and advancing front permeability measurement methods are compared. The results indicate that both methods yield similar permeabilities for a plain weave, bi-axial fiberglass fabric. Also, a method to determine principal directions and permeabilities is discussed and results are shown for a multi-axial warp knit preform. The flow of resin through a blade-stiffened preform was modeled and experiments were completed to verify the results. The predicted inlet pressure was approximately 65% of the measured value. A parametric study was performed to explain differences in measured and predicted flow front advancement and inlet pressures. Furthermore, PR-500 epoxy resin/IM7 8HS carbon fabric flat panels were fabricated by the Resin Transfer Molding process. Tests were completed utilizing both perimeter injection and center-port injection as resin inlet boundary conditions. The mold was instrumented with FDEMS sensors, pressure transducers, and thermocouples to monitor the process conditions. Results include a comparison of predicted and measured inlet pressures and flow front position. For the perimeter injection case, the measured inlet pressure and flow front results compared well to the predicted results. The results of the center-port injection case showed that the predicted inlet pressure was approximately 50% of the measured inlet pressure. Also, measured flow front position data did not agree well with the predicted results. Possible reasons for error include fiber deformation at the resin inlet and a lag in FDEMS sensor wet-out due to low mold pressures.

Investigations of Heat Transfer in Vacuum between Room Temperature and 80 K

NASA Astrophysics Data System (ADS)

Hooks, J.; Demko, J. A.; E Fesmire, J.; Matsumoto, T.

2017-12-01

The heat transfer between room temperature and 80 K is controlled using various insulating material combinations. The modes of heat transfer are well established to be conduction and thermal radiation when in a vacuum. Multi-Layer Insulation (MLI) in a vacuum has long been the best approach. Typically this layered system is applied to the cold surface. This paper investigates the application of MLI to both the cold and warm surface to see whether there is a significant difference. In addition if MLI is on the warm surface, the cold side of the MLI may be below the critical temperature of some high temperature superconducting (HTS) materials. It has been proposed that HTS materials can serve to block thermal radiation. An experiment is conducted to measure this effect. Boil-off calorimetry is the method of measuring the heat transfer.

Ionic-liquid-impregnated resin for the microwave-assisted solid-liquid extraction of triazine herbicides in honey.

PubMed

Wu, Lijie; Song, Ying; Hu, Mingzhu; Yu, Cui; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

2015-09-01

Microwave-assisted ionic-liquid-impregnated resin solid-liquid extraction was developed for the extraction of triazine herbicides, including cyanazine, metribuzin, desmetryn, secbumeton, terbumeton, terbuthylazine, dimethametryn, and dipropetryn in honey samples. The ionic-liquid-impregnated resin was prepared by immobilizing 1-hexyl-3-methylimidazolium hexafluorophosphate in the microspores of resin. The resin was used as the extraction adsorbent. The extraction and enrichment of analytes were performed in a single step. The extraction time can be shortened greatly with the help of microwave. The effects of experimental parameters including type of resin, type of ionic liquid, mass ratio of resin to ionic liquid, extraction time, amount of the impregnated resin, extraction temperature, salt concentration, and desorption conditions on the extraction efficiency, were investigated. A Box-Behnken design was applied to the selection of the experimental parameters. The recoveries were in the range of 80.1 to 103.4% and the relative standard deviations were lower than 6.8%. The present method was applied to the analysis of honey samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mass transfer parameters of celeriac during vacuum drying

NASA Astrophysics Data System (ADS)

Beigi, Mohsen

2017-04-01

An accurate prediction of moisture transfer parameters is very important for efficient mass transfer analysis, accurate modelling of drying process, and better designing of new dryers and optimization of existing drying process. The present study aimed to investigate the influence of temperature (e.g., 55, 65 and 75 °C) and chamber pressure (e.g., 0.1, 3, 7, 10, 13 and 17 kPa) on effective diffusivity and convective mass transfer coefficient of celeriac slices during vacuum drying. The obtained Biot number indicated that the moisture transfer in the celeriac slices was controlled by both internal and external resistance. The effective diffusivity obtained to be in the ranges of 7.5231 × 10-10-3.8015 × 10-9 m2 s-1. The results showed that the diffusivity increased with increasing temperature and decreasing pressure. The mass transfer coefficient values varied from 4.6789 × 10-7 to 1.0059 × 10-6 m s-1, and any increment in drying temperature and pressure caused an increment in the coefficient.

Resin transfer molding for advanced composite primary wing and fuselage structures

NASA Technical Reports Server (NTRS)

Markus, Alan

1992-01-01

The stitching and resin transfer molding (RTM) processes developed at Douglas Aircraft Co. are successfully demonstrating significant cost reductions with good damage tolerance properties. These attributes were identified as critical to application of advanced composite materials to commercial aircraft primary structures. The RTM/stitching developments, cost analyses, and test results are discussed of the NASA Advanced Composites Technology program.

Development of Subischial Prosthetic Sockets with Vacuum-Assisted Suspension for Highly Active Persons with Transfemoral Amputations

DTIC Science & Technology

2012-10-01

materials to facilitate dissemination of this technique. 15. SUBJECT TERMS Transfemoral amputation, sub-ischial socket, prosthesis , vacuum-assisted...an appropriate mechanical pump to create suitable vacuum for suspension of the prosthesis ...sockets of highly active prosthesis users

Development of Subischial Prosthetic Sockets with Vacuum-Assisted Suspension for Highly Active Persons with Transfemoral Amputations

DTIC Science & Technology

2014-10-01

Award Number: W81XWH-10-1-0744 TITLE: Development of Subischial Prosthetic Sockets with Vacuum...REPORT TYPE Annual 3. DATES COVERED 15 Sep 2013 – 14 Sep 2014 4. TITLE AND SUBTITLE Development of Subischial Prosthetic Sockets with Vacuum...to develop a highly flexible sub-ischial prosthetic socket with assisted-vacuum suspension for highly active persons with transfemoral amputation. The

Protection of polyphenols in blueberry juice by vacuum-assisted block freeze concentration.

PubMed

Orellana-Palma, Patricio; Petzold, Guillermo; Pierre, Lissage; Pensaben, José Manuel

2017-11-01

Block freeze concentration allows produces high-quality cryoconcentrates with important protection of valuable components from fresh fruit juices. The aim of this study was to investigate the use of vacuum-assisted block freeze concentration under different experimental conditions to protect polyphenols in the elaboration of concentrated blueberry juice. Fresh blueberry juice was radial or unidirectional frozen at -20 and -80 °C for 12 h and vacuum process was performed at 80 kPa during 120 min. Results showed a significant solute increased in the concentrated fraction in all treatments, and the best treatment was - 20 °C/unidirectional with a value of ≈63 °Brix, equivalent to an increase of 3.8 times in the total polyphenol content (76% of retention). The color of concentrated samples was darker than the initial sample, with ΔE* values of >25 CIELab units in all treatments. The vacuum-assisted block freeze concentrations was an effective technology for protecting polyphenols and obtain a concentrated with a higher concentration of solids from blueberry juice, as well as interesting values of process parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Assessment of vacuum-assisted vaginal delivery in a frank breech presentation].

PubMed

Bleu, G; Deruelle, P; Demetz, J; Michel, S; Dufour, P; Depret, S; Subtil, D

2015-02-01

After verification of the eligibility criteria and with an obstetrician familiar with the specific maneuvers likely to be needed, vaginal delivery of breech presentations is possible. If problems arise during the active pushing phase of labor, vacuum extraction has been described in the literature for this uncommon condition with limited series. The aim of this study is to assess retrospectively vacuum extraction in frank breech presentation in our center. This retrospective study of trials of vaginal delivery of fetuses in breech presentation at term compares cases according to whether they did or did not use a vacuum extraction. During a two-year period, 83 patients, whom had trials of vaginal delivery in breech presentations, reached the active pushing/bearing down stage after complete cervical dilatation. Vacuum assistance was applied in six of these (7.2 %). The failure rate for vaginal delivery was significantly higher in the group with compared to without vacuum extraction (33.3 % versus 6.5 %, P<0.05). Moreover, the mean pH at birth was significantly lower in the group with vacuum extraction (7.12±0.11 versus 7.20±0.08, P<0.05), and these infants more frequently had deep cutaneous injuries (66.7 % versus 26.0 %, P<0.05). In fetuses in breech presentation, when vaginal delivery failed, it seems to be safer for the fetuses to perform caesarean section rather than attempt vacuum extraction. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Vacuum-assisted fluid flow in microchannels to pattern substrates and cells.

PubMed

Shrirao, Anil B; Kung, Frank H; Yip, Derek; Cho, Cheul H; Townes-Anderson, Ellen

2014-09-01

Substrate and cell patterning are widely used techniques in cell biology to study cell-to-cell and cell-substrate interactions. Conventional patterning techniques work well only with simple shapes, small areas and selected bio-materials. This paper describes a method to distribute cell suspensions as well as substrate solutions into complex, long, closed (dead-end) polydimethylsiloxane (PDMS) microchannels using negative pressure. Our method builds upon a previous vacuum-assisted method used for micromolding (Jeon et al 1999 Adv. Mater 11 946) and successfully patterned collagen-I, fibronectin and Sal-1 substrates on glass and polystyrene surfaces, filling microchannels with lengths up to 120 mm and covering areas up to 13 × 10 mm(2). Vacuum-patterned substrates were subsequently used to culture mammalian PC12 and fibroblast cells and amphibian neurons. Cells were also patterned directly by injecting cell suspensions into microchannels using vacuum. Fibroblast and neuronal cells patterned using vacuum showed normal growth and minimal cell death indicating no adverse effects of vacuum on cells. Our method fills reversibly sealed PDMS microchannels. This enables the user to remove the PDMS microchannel cast and access the patterned biomaterial or cells for further experimental purposes. Overall, this is a straightforward technique that has broad applicability for cell biology.

Vacuum-assisted Fluid Flow in Microchannels to Pattern Substrates and Cells

PubMed Central

Shrirao, Anil B.; Kung, Frank H.; Yip, Derek; Cho, Cheul H.; Townes-Anderson, Ellen

2014-01-01

Substrate and cell patterning are widely used techniques in cell biology to study cell-to-cell and cell-to-substrate interactions. Conventional patterning techniques work well only with simple shapes, small areas and selected bio-materials. This paper describes a method to distribute cell suspensions as well as substrate solutions into complex, long, closed (dead-end) polydimethylsiloxane (PDMS) microchannels using negative pressure. Our method builds upon a previous vacuum-assisted method used for micromolding (Jeon, Choi et al. 1999) and successfully patterned collagen-I, fibronectin and Sal-1 substrates on glass and polystyrene surfaces, filling microchannels with lengths up to 120 mm and covering areas up to 13 × 10 mm2. Vacuum-patterned substrates were subsequently used to culture mammalian PC12 and fibroblast cells and amphibian neurons. Cells were also patterned directly by injecting cell suspensions into microchannels using vacuum. Fibroblast and neuronal cells patterned using vacuum showed normal growth and minimal cell death indicating no adverse effects of vacuum on cells. Our method fills reversibly sealed PDMS microchannels. This enables the user to remove the PDMS microchannel cast and access the patterned biomaterial or cells for further experimental purposes. Overall, this is a straightforward technique that has broad applicability for cell biology. PMID:24989641

Acid etching of titanium for bonding with veneering composite resins.

PubMed

Ban, Seiji; Taniki, Toshio; Sato, Hideo; Kono, Hiroshi; Iwaya, Yukari; Miyamoto, Motoharu

2006-06-01

Commercially pure titanium (cpTi) was etched using three concentrated acids: 18% HCl, 43% H3PO4, and 48% H2SO4. The bond strengths between five types of veneering composite resin and eight cpTi treatments (involving combinations of sandblasting, acid etching in 48% H2SO4, and vacuum firing) were determined before and after 10,000 and 20,000 thermal cycles. There were no significant differences in the bond strength of resin to cpTi after etching in 48% H2SO4 at 90 degrees C for 15 minutes, at 60 degrees C for 15, 30, or 60 minutes, and after sandblasting with and without vacuum firing (p > 0.05); moreover, these treatments yielded the highest values. As for vacuum firing, it had no significant effect on resin bond strength to cpTi before or after 10,000 and 20,000 thermal cycles. We therefore concluded that acid etching in concentrated H2SO4 is a simple and effective surface modification method of titanium for bonding to veneering composite resins.

Orbital-angular-momentum transfer to optically levitated microparticles in vacuum

NASA Astrophysics Data System (ADS)

Mazilu, Michael; Arita, Yoshihiko; Vettenburg, Tom; Auñón, Juan M.; Wright, Ewan M.; Dholakia, Kishan

2016-11-01

We demonstrate the transfer of orbital angular momentum to an optically levitated microparticle in vacuum. The microparticle is placed within a Laguerre-Gaussian beam and orbits the annular beam profile with increasing angular velocity as the air drag coefficient is reduced. We explore the particle dynamics as a function of the topological charge of the levitating beam. Our results reveal that there is a fundamental limit to the orbital angular momentum that may be transferred to a trapped particle, dependent upon the beam parameters and inertial forces present.

Resin-assisted Enrichment of N-terminal Peptides for Characterizing Proteolytic Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jong Seo; Dai, Ziyu; Aryal, Uma K.

2013-06-17

Proteolytic processing is a ubiquitous, irreversible posttranslational modification that plays an important role in cellular regulation in all living organisms. Herein we report a resin-assisted positive selection method for specifically enriching protein N-terminal peptides to facilitate the characterization of proteolytic processing events by liquid chromatography-tandem mass spectrometry. In this approach, proteins are initially reduced and alkylated and their lysine residues are converted to homoarginines. Then, protein N-termini are selectively converted to reactive thiol groups. We demonstrate that these sequential reactions were achieved with nearly quantitative efficiencies. Thiol-containing N-terminal peptides are then captured (>98% efficiency) by a thiol-affinity resin, a significantmore » improvement over the traditional avidin/biotin enrichment. Application to cell lysates of Aspergillus niger, a filamentous fungus of interest for biomass degradation, enabled the identification of 1672 unique protein N-termini and proteolytic cleavage sites from 690 unique proteins.« less

Evaluation of Double-Vacuum-Bag Process For Composite Fabrication

NASA Technical Reports Server (NTRS)

Hou, T. H.; Jensen, B. J.

2004-01-01

A non-autoclave vacuum bag process using atmospheric pressure alone that eliminates the need for external pressure normally supplied by an autoclave or a press is an attractive method for composite fabrication. This type of process does not require large capital expenditures for tooling and processing equipment. In the molding cycle (temperature/pressure profile) for a given composite system, the vacuum application point has to be carefully selected to achieve the final consolidated laminate net shape and resin content without excessive resin squeeze-out. The traditional single-vacuum- bag (SVB) process is best suited for molding epoxy matrix based composites because of their superior flow and the absence of reaction by-products or other volatiles. Other classes of materials, such as polyimides and phenolics, generate water during cure. In addition, these materials are commonly synthesized as oligomers using solvents to facilitate processability. Volatiles (solvents and reaction byproducts) management therefore becomes a critical issue. SVB molding, without additional pressure, normally fails to yield void-free quality composites for these classes of resin systems. A double-vacuum- bag (DVB) process for volatile management was envisioned, designed and built at the NASA Langley Research Center. This experimental DVB process affords superior volatiles management compared to the traditional SVB process. Void-free composites are consistently fabricated as measured by C-scan and optical photomicroscopy for high performance polyimide and phenolic resins.

Vacuum-Assisted, Constant-Force Exercise Device

NASA Technical Reports Server (NTRS)

Hansen, Christopher P.; Jensen, Scott

2006-01-01

The vacuum-assisted, constant-force exercise device (VAC-FED) has been proposed to fill a need for a safe, reliable exercise machine that would provide constant loads that could range from 20 to 250 lb (0.09 to 1.12 kN) with strokes that could range from 6 to 36 in. (0.15 to 0.91 m). The VAC-FED was originally intended to enable astronauts in microgravity to simulate the lifting of free weights, but it could just as well be used on Earth for simulated weight lifting and other constant-force exercises. Because the VAC-FED would utilize atmospheric/vacuum differential pressure instead of weights to generate force, it could weigh considerably less than either a set of free weights or a typical conventional exercise machine based on weights. Also, the use of atmospheric/ vacuum differential pressure to generate force would render the VAC-FED inherently safer, relative to free weights and to conventional exercise machines that utilize springs to generate forces. The overall function of the VAC-FED would be to generate a constant tensile force in an output cable, which would be attached to a bar, handle, or other exercise interface. The primary force generator in the VAC-FED would be a piston in a cylinder. The piston would separate a volume vented to atmosphere at one end of the cylinder from an evacuated volume at the other end of the cylinder (see figure). Hence, neglecting friction at the piston seals, the force generated would be nearly constant equal to the area of the piston multiplied by the atmospheric/vacuum differential pressure. In the vented volume in the cylinder, a direct-force cable would be looped around a pulley on the piston, doubling the stroke and halving the tension. One end of the direct-force cable would be anchored to a cylinder cap; the other end of the direct-force cable would be wrapped around a variable-ratio pulley that would couple tension to the output cable. As its name suggests, the variable-ratio pulley would contain a mechanism that

Development of Sub-Ischial Prosthetic Sockets with Vacuum-Assisted Suspension for Highly Active Persons with Transfemoral Amputations

DTIC Science & Technology

2013-10-01

15. SUBJECT TERMS Transfemoral amputation, sub-ischial socket, prosthesis , vacuum-assisted suspension 16. SECURITY CLASSIFICATION OF: 17...vacuum for suspension of the prosthesis ...14 Task 6 Determine range of volumes to be evacuated from transfemoral sockets of highly active prosthesis users

Automated Fabrication Technologies for High Performance Polymer Composites

NASA Technical Reports Server (NTRS)

Shuart , M. J.; Johnston, N. J.; Dexter, H. B.; Marchello, J. M.; Grenoble, R. W.

1998-01-01

New fabrication technologies are being exploited for building high graphite-fiber-reinforced composite structure. Stitched fiber preforms and resin film infusion have been successfully demonstrated for large, composite wing structures. Other automatic processes being developed include automated placement of tacky, drapable epoxy towpreg, automated heated head placement of consolidated ribbon/tape, and vacuum-assisted resin transfer molding. These methods have the potential to yield low cost high performance structures by fabricating composite structures to net shape out-of-autoclave.

Analytical modeling and sensor monitoring for optimal processing of advanced textile structural composites by resin transfer molding

NASA Technical Reports Server (NTRS)

Loos, Alfred C.; Macrae, John D.; Hammond, Vincent H.; Kranbuehl, David E.; Hart, Sean M.; Hasko, Gregory H.; Markus, Alan M.

1993-01-01

A two-dimensional model of the resin transfer molding (RTM) process was developed which can be used to simulate the infiltration of resin into an anisotropic fibrous preform. Frequency dependent electromagnetic sensing (FDEMS) has been developed for in situ monitoring of the RTM process. Flow visualization tests were performed to obtain data which can be used to verify the sensor measurements and the model predictions. Results of the tests showed that FDEMS can accurately detect the position of the resin flow-front during mold filling, and that the model predicted flow-front patterns agreed well with the measured flow-front patterns.

Cleaner Vacuum-Bag Curing

NASA Technical Reports Server (NTRS)

Clemons, J. M.; Penn, B. G.; Ledbetter, Frank E., III; Daniels, J. G.

1987-01-01

Improvement upon recommended procedures saves time and expense. Autoclave molding in vacuum bag cleaner if adhesive-backed covering placed around caul plate as well as on mold plate. Covering easy to remove after curing and leaves caul plate free of resin deposits.

PETIs as High-Temperature Resin-Transfer-Molding Materials

NASA Technical Reports Server (NTRS)

Connell, John N.; Smith, Joseph G., Jr.; Hergenrother, Paul M.

2005-01-01

Compositions of, and processes for fabricating, high-temperature composite materials from phenylethynyl-terminated imide (PETI) oligomers by resin-transfer molding (RTM) and resin infusion have been developed. Composites having a combination of excellent mechanical properties and long-term high-temperature stability have been readily fabricated. These materials are particularly useful for the fabrication of high-temperature structures for jet-engine components, structural components on highspeed aircraft, spacecraft, and missiles. Phenylethynyl-terminated amide acid oligomers that are precursors of PETI oligomers are easily made through the reaction of a mixture of aromatic diamines with aromatic dianhydrides at high stoichiometric offsets and 4-phenylethynylphthalic anhydride (PEPA) as an end-capper in a polar solvent such as N-methylpyrrolidinone (NMP). These oligomers are subsequently cyclodehydrated -- for example, by heating the solution in the presence of toluene to remove the water by azeotropic distillation to form low-molecular-weight imide oligomers. More precisely, what is obtained is a mixture of PETI oligomeric species, spanning a range of molecular weights, that exhibits a stable melt viscosity of less than approximately 60 poise (and generally less than 10 poise) at a temperature below 300 deg C. After curing of the oligomers at a temperature of 371 deg C, the resulting polymer can have a glass-transition temperature (Tg) as high as 375 C, the exact value depending on the compositions.

A Versatile High-Vacuum Cryo-transfer System for Cryo-microscopy and Analytics

PubMed Central

Tacke, Sebastian; Krzyzanek, Vladislav; Nüsse, Harald; Wepf, Roger Albert; Klingauf, Jürgen; Reichelt, Rudolf

2016-01-01

Cryogenic microscopy methods have gained increasing popularity, as they offer an unaltered view on the architecture of biological specimens. As a prerequisite, samples must be handled under cryogenic conditions below their recrystallization temperature, and contamination during sample transfer and handling must be prevented. We present a high-vacuum cryo-transfer system that streamlines the entire handling of frozen-hydrated samples from the vitrification process to low temperature imaging for scanning transmission electron microscopy and transmission electron microscopy. A template for cryo-electron microscopy and multimodal cryo-imaging approaches with numerous sample transfer steps is presented. PMID:26910419

Recovery of materials from waste printed circuit boards by vacuum pyrolysis and vacuum centrifugal separation.

PubMed

Zhou, Yihui; Wu, Wenbiao; Qiu, Keqiang

2010-11-01

In this research, a two-step process consisting of vacuum pyrolysis and vacuum centrifugal separation was employed to treat waste printed circuit boards (WPCBs). Firstly, WPCBs were pyrolysed under vacuum condition at 600 °C for 30 min in a lab-scale reactor. Then, the obtained pyrolysis residue was heated under vacuum until the solder was melted, and then the molten solder was separated from the pyrolysis residue by the centrifugal force. The results of vacuum pyrolysis showed that the type-A of WPCBs (the base plates of which was made from cellulose paper reinforced phenolic resin) pyrolysed to form an average of 67.97 wt.% residue, 27.73 wt.% oil, and 4.30 wt.% gas; and pyrolysis of the type-B of WPCBs (the base plates of which was made from glass fiber reinforced epoxy resin) led to an average mass balance of 72.20 wt.% residue, 21.45 wt.% oil, and 6.35 wt.% gas. The results of vacuum centrifugal separation showed that the separation of solder was complete when the pyrolysis residue was heated at 400 °C, and the rotating drum was rotated at 1200 rpm for 10 min. The pyrolysis oil and gas can be used as fuel or chemical feedstock after treatment. The pyrolysis residue after solder separation contained various metals, glass fibers and other inorganic materials, which could be recycled for further processing. The recovered solder can be reused directly and it can also be a good resource of lead and tin for refining. Copyright © 2010 Elsevier Ltd. All rights reserved.

Fiber Metal Laminates Made by the VARTM Process

NASA Technical Reports Server (NTRS)

Jensen, Brian J.; Cano, Roberto J.; Hales, Stephen J.; Alexa, Joel A.; Weiser, Erik S.; Loos, Alfred; Johnson, W.S.

2009-01-01

Fiber metal laminates (FMLs) are multi-component materials utilizing metals, fibers and matrix resins. Tailoring their properties is readily achievable by varying one or more of these components. Established FMLs like GLARE utilize aluminum foils, glass fibers and epoxy matrices and are manufactured using an autoclave. Two new processes for manufacturing FMLs using vacuum assisted resin transfer molding (VARTM) have been developed at the NASA Langley Research Center (LaRC). A description of these processes and the resulting FMLs are presented.

Integrated cooling-vacuum-assisted 1540-nm erbium:glass laser is effective in treating mild-to-moderate acne vulgaris.

PubMed

Politi, Y; Levi, A; Enk, C D; Lapidoth, M

2015-12-01

Acne treatment by a mid-infrared laser may be unsatisfactory due to deeply situated acne-affected sebaceous glands which serve as its target. Skin manipulation by vacuum and contact cooling may improve laser-skin interaction, reduce pain sensation, and increase overall safety and efficacy. To evaluate the safety and efficacy of acne treatment using an integrated cooling-vacuum-assisted 1540-nm erbium:glass laser, a prospective interventional study was conducted. It included 12 patients (seven men and five women) suffering from mild-to-moderate acne vulgaris. The device utilizes a mid-infrared 1540-nm laser (Alma Lasers Ltd. Caesarea, Israel), which is integrated with combined cooling-vacuum-assisted technology. An acne lesion is initially manipulated upon contact by a vacuum-cooling-assisted tip, followed by three to four stacked laser pulses (500-600 mJ, 4 mm spot size, and frequency of 2 Hz). Patients underwent four to six treatment sessions with a 2-week interval and were followed-up 1 and 3 months after the last treatment. Clinical photographs were taken by high-resolution digital camera before and after treatment. Clinical evaluation was performed by two independent dermatologists, and results were graded on a scale of 0 (exacerbation) to 4 (76-100 % improvement). Patients' and physicians' satisfaction was also recorded. Pain perception and adverse effects were evaluated as well. All patients demonstrated a moderate to significant improvement (average score of 3.6 and 2.0 within 1 and 3 months, respectively, following last treatment session). No side effects, besides a transient erythema, were observed. Cooling-vacuum-assisted 1540-nm laser is safe and effective for the treatment of acne vulgaris.

[Interhospital transfer of ECMO-assisted patients in Martinique].

PubMed

Roger, D; Dudouit, J-M; Résière, D; Mehdaoui, H; Courcier, D; Villain, L; Léonard, C; Roques, F; Lebreton, G

2013-05-01

The transportation of critically ill patients in the French West Indies represents a real challenge; in order to ensure territorial continuity of health care provision, the cardiac surgical department of the Fort-de-France Hospital created a mobile ECMO/ECLS unit. The aim of our work is to describe the logistical, technical and financial aspects of the interhospital transfer of ECMO/ECLS-assisted patients in the French Caribbean. All ECMO/ECLS-assisted patients in the French Antilles-Guyane area subsequently repatriated towards the Fort-de-France Hospital were included from December 29th, 2009 to September 30th, 2011. Indication and type of the extracorporeal assistance used, location of departure, type of transport vehicle, complications during transfer, survival after hospital discharge and direct costs were collected. Nineteen patients were supported by our mobile unit far away from our centre (sex-ratio 0.63, median age 34years old [16-64]). Twelve were assisted by ECMO for a refractory ARDS, and seven were assisted by ECLS for a refractory cardiogenic shock. Four patients were transferred by ambulance (7-29km), seven by helicopter (190-440km), and eight by plane (440-1430km). No patient died during transfer. No major adverse event occurred during these transfers. Fifteen patients survived. An economic assessment was conducted. Interhospital transfer of ECMO/ECLS-assisted patients by land or air is technically feasible under perfectly secure conditions in our area. Prior coordination of this activity has helped to make it affordable. Copyright © 2013 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

Investigation of the shear thinning behavior of epoxy resins for utilization in vibration assisted liquid composite molding processes

NASA Astrophysics Data System (ADS)

Meier, R.; Kirdar, C.; Rudolph, N.; Zaremba, S.; Drechsler, K.

2014-05-01

Efficient production and consumption of energy are of greatest importance for contemporary industries and their products. This has led to an increasing application of lightweight materials in general and of Carbon Fiber Reinforced Plastics (CFRP) in particular. However, broader application of CFRP is often limited by high costs and manual labor production processes. These constraints are addressed by Liquid Composite Molding (LCM) processes. In LCM a dry fibrous preform is placed into a cavity and infiltrated mostly by thermoset resins; epoxy resins are wide spread in CFRP applications. One crucial parameter for a fast mold filling is the viscosity of the resin, which is affected by the applied shear rates as well as temperature and curing time. The work presented focuses on the characterization of the shear thinning behavior of epoxy resins. Furthermore, the correlation with the conditions in vibration assisted LCM processes, where additional shear rates are created during manufacture, is discussed. Higher shear rates result from high frequencies and/or high amplitudes of the vibration motions which are created by a vibration engine mounted on the mold. In rheological investigations the shear thinning behavior of a representative epoxy resin is studied by means of rotational and oscillatory experiments. Moreover, possible effects of shear rates on the chemical curing reaction are studied. Here, the time for gelation is measured for different levels of shear rates in a pre-shearing phase. Based on the rheological studies, the beneficial effect of vibration assistance in LCM processes with respect to mold filling can further be predicted and utilized.

Occiput posterior fetal head position increases the risk of anal sphincter injury in vacuum-assisted deliveries.

PubMed

Wu, Jennifer M; Williams, Kathryn S; Hundley, Andrew F; Connolly, AnnaMarie; Visco, Anthony G

2005-08-01

The purpose of this study was to determine whether an occiput posterior (OP) fetal head position increases the risk for anal sphincter injury when compared with an occiput anterior (OA) position in vacuum-assisted deliveries. We conducted a retrospective cohort study of 393 vacuum-assisted singleton vaginal deliveries. Maternal demographics and obstetric and neonatal data were collected from an obstetric database and chart review. Within the OP group, 41.7% developed a third- or fourth-degree laceration compared with 22.0% in the OA group (OR 2.5, 95% CI 1.4-4.7). In a logistic regression model that controlled for BMI, race, nulliparity, length of second stage, episiotomy, birth weight, head circumference, and fetal head position, OP position was 4.0 times (95% CI 1.7-9.6) more likely to be associated with an anal sphincter injury than OA position. Among vacuum deliveries, an OP head position confers an incrementally increased risk for anal sphincter injury over an OA position.

Composite Structures and Materials Research at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, roberto J.

2003-01-01

A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI), Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

Composite Structures and Materials Research at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Starnes, James H., Jr.; Dexter, H. Benson; Johnston, Norman J.; Ambur, Damodar R.; Cano, Roberto J.

2001-01-01

A summary of recent composite structures and materials research at NASA Langley Research Center is presented. Fabrication research to develop low-cost automated robotic fabrication procedures for thermosetting and thermoplastic composite materials, and low-cost liquid molding processes for preformed textile materials is described. Robotic fabrication procedures discussed include ply-by-ply, cure-on-the-fly heated placement head and out-of-autoclave electron-beam cure methods for tow and tape thermosetting and thermoplastic materials. Liquid molding fabrication processes described include Resin Film Infusion (RFI) Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). Results for a full-scale composite wing box are summarized to identify the performance of materials and structures fabricated with these low-cost fabrication methods.

Mechanical characterization and structural analysis of recycled fiber-reinforced-polymer resin-transfer-molded beams

NASA Astrophysics Data System (ADS)

Tan, Eugene Wie Loon

1999-09-01

The present investigation was focussed on the mechanical characterization and structural analysis of resin-transfer-molded beams containing recycled fiber-reinforced polymers. The beams were structurally reinforced with continuous unidirectional glass fibers. The reinforcing filler materials consisted entirely of recycled fiber-reinforced polymer wastes (trim and overspray). The principal resin was a 100-percent dicyclo-pentadiene unsaturated polyester specially formulated with very low viscosity for resin transfer molding. Variations of the resin transfer molding technique were employed to produce specimens for material characterization. The basic materials that constituted the structural beams, continuous-glass-fiber-reinforced, recycled-trim-filled and recycled-overspray-filled unsaturated polyesters, were fully characterized in axial and transverse compression and tension, and inplane and interlaminar shear, to ascertain their strengths, ultimate strains, elastic moduli and Poisson's ratios. Experimentally determined mechanical properties of the recycled-trim-filled and recycled-overspray-filled materials from the present investigation were superior to those of unsaturated polyester polymer concretes and Portland cement concretes. Mechanical testing and finite element analyses of flexure (1 x 1 x 20 in) and beam (2 x 4 x 40 in) specimens were conducted. These structurally-reinforced specimens were tested and analyzed in four-point, third-point flexure to determine their ultimate loads, maximum fiber stresses and mid-span deflections. The experimentally determined load capacities of these specimens were compared to those of equivalent steel-reinforced Portland cement concrete beams computed using reinforced concrete theory. Mechanics of materials beam theory was utilized to predict the ultimate loads and mid-span deflections of the flexure and beam specimens. However, these predictions proved to be severely inadequate. Finite element (fracture propagation

Comparison of resin film infusion, resin transfer molding, and consolidation of textile preforms for primary aircraft structure

NASA Technical Reports Server (NTRS)

Suarez, J.; Dastin, S.

1992-01-01

Innovative design concepts and cost effective fabrication processes were developed for damage tolerant primary structures that can perform at a design ultimate strain level of 6000 micro inch/inch. Attention focused on the use of textile high performance fiber reinforcement concepts that provide improved damage tolerance and out-of-plane load capability, low cost resin film infusion (RFI) and resin transfer molding (RTM) processes, and thermoplastic forming concepts. The fabrication of wing 'Y' spars by four different materials and/or processes methods is described: fabricated using IM7 angle interlock 0 to 90 deg woven preforms with + or - 45 deg plies stitched with Toray high strength graphite thread and processed using RFI and 3501-6 epoxy; fabricated using G40-800 knitted/stitched preforms and processed using RFI and 3501-6 epoxy; fabricated using G40-800 knitted/stitched preforms using RTM and Tactix 123/H41 epoxy; and fabricated preforms using AS4(6K)/PEEK 150 g commingled angle interlock 0 to 90 deg woven preforms with + or - 45 deg commingled plies stitched using high strength graphite thread and processed by consolidation. Structural efficiency, processability, and acquisition cost are compared.

Flat epithelial atypia in directional vacuum-assisted biopsy of breast microcalcifications: surgical excision may not be necessary.

PubMed

McCroskey, Zulfia; Sneige, Nour; Herman, Carolyn R; Miller, Ross A; Venta, Luz A; Ro, Jae Y; Schwartz, Mary R; Ayala, Alberto G

2018-02-21

The aim of this study was to analyze the clinicopathological features of patients with flat epithelial atypia, diagnosed in directional vacuum-assisted biopsy targeting microcalcifications, to identify upgrade rate to in situ ductal or invasive breast carcinoma, and determine factors predicting carcinoma in the subsequent excision. We retrospectively evaluated the histological, clinical, and mammographic features of 69 cases from 65 women, with directional vacuum-assisted biopsy-diagnosed flat epithelial atypia with or without atypical ductal hyperplasia or atypical lobular hyperplasia, which underwent subsequent surgical excision. The extent and percentage of microcalcifications sampled by directional vacuum-assisted biopsy were evaluated by mammography. All biopsy and surgical excision slides were reviewed. The age of the women ranged from 40 to 85 years (mean 57 years). All patients presented with mammographically detected microcalcifications only, except in one case that had associated architectural distortion. Extent of calcifications ranged from <1 cm (n = 47), 1-3 cm (n = 15) to > 3 cm (n = 6), and no measurement (n = 1). A mean of 11 cores (range 6-25) was obtained from each lesion. Post-biopsy mammogram revealed >90% removal of calcifications in 81% of cases. Pure flat epithelial atypia represented nearly two-thirds of directional vacuum-assisted biopsy specimens (n = 43, 62%), while flat epithelial atypia coexisted with atypical ductal hyperplasia (18 cases, 26%), or atypical lobular hyperplasia (8 cases, 12%). Upon excision, none of the cases were upgraded to in situ ductal or invasive breast cancer. In one case, however, an incidental, tubular carcinoma (4 mm) was found away from biopsy site. Excluding this case, the upgrade rate was 0%. Our study adds to the growing evidence that diagnosis of flat epithelial atypia on directional vacuum-assisted biopsy for microcalcifications as the only imaging finding is not associated

Effects of Amine and Anhydride Curing Agents on the VARTM Matrix Processing Properties

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Hubert, Pascal; Song, Xiaolan; Cano, Roberto J.; Loos, Alfred C.; Pipes, R. Byron

2002-01-01

To ensure successful application of composite structure for aerospace vehicles, it is necessary to develop material systems that meet a variety of requirements. The industry has recently developed a number of low-viscosity epoxy resins to meet the processing requirements associated with vacuum assisted resin transfer molding (VARTM) of aerospace components. The curing kinetics and viscosity of two of these resins, an amine-cured epoxy system, Applied Poleramic, Inc. VR-56-4 1, and an anhydride-cured epoxy system, A.T.A.R.D. Laboratories SI-ZG-5A, have been characterized for application in the VARTM process. Simulations were carried out using the process model, COMPRO, to examine heat transfer, curing kinetics and viscosity for different panel thicknesses and cure cycles. Results of these simulations indicate that the two resins have significantly different curing behaviors and flow characteristics.

Ultrasound-Guided Core-Needle Versus Vacuum-Assisted Breast Biopsy: A Cost Analysis Based on the American Society of Breast Surgeons' Mastery of Breast Surgery Registry.

PubMed

Grady, Ian; Vasquez, Tony; Tawfik, Sara; Grady, Sean

2017-03-01

To evaluate the cost-efficacy of vacuum-assisted ultrasound-guided breast biopsy instruments compared to ultrasound-guided 14-gauge spring-loaded core-needle biopsy. The American Society of Breast Surgeons' Mastery of Breast Surgery Registry was reviewed. Biopsy findings, any rebiopsy, and the instrument used were abstracted for 31,451 ultrasound-guided biopsy procedures performed between 2001 and July 2014. Rates of cancer diagnosis and rebiopsy were calculated for each instrument. A linear mathematical model was developed to calculate total cost per cancer diagnosis, including procedural costs and the costs of any additional surgical rebiopsy procedures. Mean cost per cancer diagnosis with confidence limits was then determined for 14-gauge spring-loaded core-needle biopsy and 14 different vacuum-assisted instruments. For 14-gauge spring-loaded core-needle biopsy, mean cost per cancer diagnosis was $4346 (4327-$4366). For the vacuum-assisted instruments, mean cost per cancer diagnosis ranged from a low of $3742 ($3732-$3752) to a high of $4779 ($4750-$4809). Vacuum-assisted instruments overall were more cost-effective than core with a mean cost per cancer diagnosis of $4052 ($4038-$4067) (p < 0.05). Tethered vacuum-assisted instruments performed best with a mean cost per cancer diagnosis of $3978 ($3964-$3991) (p < 0.05). Nontethered devices had a mean cost per cancer diagnosis of $4369 ($4350-$4388), a result no better than core (p < 0.05). Ultrasound-guided vacuum-assisted breast biopsy had a lower mean cost per cancer diagnosis than 14-gauge spring-loaded core-needle biopsy. This advantage was only seen in tethered vacuum-assisted instruments. Within device families, larger instruments tended to outperform smaller instruments.

Surface oxidation of GaN(0001): Nitrogen plasma-assisted cleaning for ultrahigh vacuum applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gangopadhyay, Subhashis; Schmidt, Thomas, E-mail: tschmidt@ifp.uni-bremen.de; Kruse, Carsten

The cleaning of metal-organic vapor-phase epitaxial GaN(0001) template layers grown on sapphire has been investigated. Different procedures, performed under ultrahigh vacuum conditions, including degassing and exposure to active nitrogen from a radio frequency nitrogen plasma source have been compared. For this purpose, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning tunneling microscopy have been employed in order to assess chemical as well as structural and morphological surface properties. Initial degassing at 600 °C under ultrahigh vacuum conditions only partially eliminates the surface contaminants. In contrast to plasma assisted nitrogen cleaning at temperatures as low as 300 °C, active-nitrogen exposure at temperaturesmore » as high as 700 °C removes the majority of oxide species from the surface. However, extended high-temperature active-nitrogen cleaning leads to severe surface roughening. Optimum results regarding both the removal of surface oxides as well as the surface structural and morphological quality have been achieved for a combination of initial low-temperature plasma-assisted cleaning, followed by a rapid nitrogen plasma-assisted cleaning at high temperature.« less

Vacuum-assisted closure as a surgical assistant in life-threatening necrotizing fasciitis in children

PubMed Central

Al-Subhi, FS; Zuker, RM; Cole, WG

2010-01-01

Necrotizing fasciitis is a severe soft tissue infection that can involve skin, subcutaneous fat, fascia and muscle. It can result in devastating sequelae including tissue necrosis, sepsis, toxic shock syndrome, cardiopulmonary collapse and death. To control rapidly spreading necrosis, early diagnosis and aggressive surgical treatment with extensive radical debridement of the affected areas is necessary, as well as systemic administration of broad-spectrum antimicrobials and, very often, intensive care support. The subatmospheric negative pressure dressing has been previously used in acute and complex wounds management. The concept of using vacuum-assisted closure dressing as another management component is presented in the current article. PMID:22131841

Acetylene-chromene terminated resins as high temperature thermosets

NASA Technical Reports Server (NTRS)

Godschalx, J. P.; Inbasekaran, M. N.; Bartos, B. R.; Scheck, D. M.; Laman, S. A.

1990-01-01

A novel phase transfer catalyzed process for the preparation of propargyl ethers has been developed. The propargyl ethers serve as precursors to a new class of thermosetting resins called acetylene-chromene terminated (ACT) resins. Heat treatment of a solution of propargyl ethers with various catalysts, followed by removal of solvent leads to the ACT resins via partial conversion of the propargyl ether groups to chromenes. This process reduces the energy content of the resin systems and reduces the amount of shrinkage found during cure. Due to the presence of the solvent the process is safe and gives rise to low viscosity products suitable for resin transfer molding and filament winding type applications. Due to the high glass transition temperature, high modulus, and low moisture uptake the cured resins display better than 232 C/wet performance. The thermal stability of the ACT resins in air at 204 C is superior to that of conventional bismaleimide resins. The resins also display excellent electrical properties.

Prospective cohort study of a new vacuum delivery device to assist with complicated labour in low-resource settings.

PubMed

Khan, Mishal; Hashmani, Farah Naz; Ahmed, Sajjad; Ahmed, Owais; Asim, Shabnam S; Wajahat, Yasmin; Sobani, Shoaib; Syed, Shershah; Qazi, Fahad

2015-02-01

Currently available vacuum devices used to assist women undergoing complicated labour are unsuitable for use in low-resource settings. The objective of this study was to evaluate the safety and feasibility of a new low-cost vacuum device, named Koohi Goth Vacuum Delivery System (KGVDS), designed for use in low-resource settings. A hospital-based, multicentre, prospective cohort study with no control group was conducted in Karachi, Pakistan. After training, KGVDS devices were made available for use by labour room staff at their discretion when instrumental delivery was indicated. Women to whom KGVDS was applied were followed from the start of labour until discharge. Feasibility was assessed in terms of successful expulsion of the foetal head following application of KGVDS and ease of use ratings. Safety was assessed by observing maternal and newborn post-delivery outcomes prior to discharge. Koohi Goth Vacuum Delivery System was applied to 137 women requiring instrumental delivery, of whom 111 (81%; 95% CI = 74-88%) successfully expelled the foetal head assisted by KGVDS and 103 (75%) stated that they would agree to use KGVDS again. There were no serious maternal or neonatal injuries or infections related to KGVDS use. The mean score for 'ease of use' given by doctors and midwives using the device was 8 of 10. Koohi Goth Vacuum Delivery System was feasible and safe to use for assisting complicated deliveries in low-resource hospitals in this initial evaluation. Our results indicate that this new device may have the potential to improve birth outcomes in settings where most mortality occurs and that further evaluations should be conducted. © 2014 John Wiley & Sons Ltd.

Vacuum-assisted wound closure and mesh-mediated fascial traction for open abdomen therapy - a systematic review.

PubMed

Acosta, Stefan; Björck, Martin; Petersson, Ulf

2017-01-01

The aim of this paper was to review the literature on vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM) in open abdomen therapy. It was designed as systematic review of observational studies. A Pub Med, EMBASE and Cochrane search from 2007/01-2016/07 was performed combining the Medical Subject Headings "vacuum", "mesh-mediated fascial traction", "temporary abdominal closure", "delayed abdominal closure", "open abdomen", "abdominal compartment syndrome", "negative pressure wound therapy" or "vacuum assisted wound closure". Eleven original studies were found including patients numbering from 7 to 111. Six studies were prospective and five were retrospective. Nine studies were on mixed surgical (n = 9), vascular (n = 6) and trauma (n = 6) patients, while two were exclusively on vascular patients. The primary fascial closure rate per protocol varied from 80-100%. The time to closure of the open abdomen varied between 9-32 days. The entero-atmospheric fistula rate varied from 0-10.0%. The in-hospital survival rate varied from 57-100%. In the largest prospective study, the incisional hernia rate among survivors at 63 months of median follow-up was 54% (27/50), and 16 (33%) repairs out of 48 incisional hernias were performed throughout the study period. The study patients reported lower short form health survey (SF-36) scores than the mean reference population, mainly dependent on the prevalence of major co-morbidities. There was no difference in SF-36 scores or a modified ventral hernia pain questionnaire (VHPQ) at 5 years of follow up between those with versus those without incisional hernias. A high primary fascial closure rate can be achieved with the vacuum-assisted wound closure and meshmediated fascial traction technique in elderly, mainly non-trauma patients, in need of prolonged open abdomen therapy.

Papilloma diagnosed at MRI-guided vacuum-assisted breast biopsy: is surgical excision still warranted?

PubMed

Brennan, Sandra B; Corben, Adriana; Liberman, Laura; Dershaw, D David; Brogi, Edi; Van Zee, Kimberly J; Morris, Elizabeth

2012-10-01

The objective of our study was to determine the frequency of cancer at surgery in breast lesions yielding papilloma at MRI-guided 9-gauge vacuum-assisted biopsy (VAB) and to determine whether any features are associated with cancer upgrade. For this study, 1487 MRI-guided vacuum-assisted biopsies performed from January 2004 to March 2011 were reviewed. Lesions yielding papilloma were identified and classified as papilloma with or without atypia. Surgical findings were reviewed to determine the cancer rate. Statistical analysis was performed and 95% CIs were calculated. Papilloma was identified in 75 of the 1487 MRI-guided vacuum-assisted biopsies (5%). These 75 papillomas occurred in 73 women with a median age of 49 years (age range, 27-70 years). Of the 75 papillomas, 25 (33%) had atypia and 50 (67%) did not on core needle biopsy. Subsequent surgery of 67 of the 75 papillomas (89%) yielded ductal carcinoma in situ (DCIS) in four (6%; 95% CI, 2-15%). Surgery yielded DCIS in two of 23 papillomas with atypia (9%; 95% CI, 1-28%) at MRI-guided VAB and in two of 44 papillomas without atypia (5%; 95% CI, 0.4-16%) at MRI-guided VAB; these cancer rates did not differ significantly (p=0.6). Postmenopausal status (p=0.04) and histologic size of less than 0.2 cm (p=0.04) had a significant association with the cancer upgrade rate. Papilloma with or without atypia was found in 5% of patients who underwent MRI-guided VAB during the study period. Surgery revealed cancer in 6%. DCIS was found at surgery in 9% of lesions yielding papilloma with atypia versus 5% of lesions yielding papilloma without atypia. For lesions yielding papilloma with or without atypia at MRI-guided VAB, surgical excision is warranted.

Matrix Assisted Ionization Vacuum (MAIV), a New Ionization Method for Biological Materials Analysis Using Mass Spectrometry*

PubMed Central

Inutan, Ellen D.; Trimpin, Sarah

2013-01-01

The introduction of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) for the mass spectrometric analysis of peptides and proteins had a dramatic impact on biological science. We now report that a wide variety of compounds, including peptides, proteins, and protein complexes, are transported directly from a solid-state small molecule matrix to gas-phase ions when placed into the vacuum of a mass spectrometer without the use of high voltage, a laser, or added heat. This ionization process produces ions having charge states similar to ESI, making the method applicable for high performance mass spectrometers designed for atmospheric pressure ionization. We demonstrate highly sensitive ionization using intermediate pressure MALDI and modified ESI sources. This matrix and vacuum assisted soft ionization method is suitable for the direct surface analysis of biological materials, including tissue, via mass spectrometry. PMID:23242551

Effect of mesh-peel ply variation on mechanical properties of E-glas composite by infusion vacuum method

NASA Astrophysics Data System (ADS)

Abdurohman, K.; Siahaan, Mabe

2018-04-01

Composite materials made of glass fiber EW-135 with epoxy lycal resin with vacuum infusion method have been performed. The dried glass fiber is arranged in a mold then connected to a vacuum machine and a resin tube. Then, the vacuum machine is turned on and at the same time the resin is sucked and flowed into the mold. This paper reports on the effect of using mesh- peel ply singles on upper-side laminates called A and the effect of using double mesh-peel ply on upper and lower-side laminates call B with glass fiber arrangement is normal and ± 450 in vacuum infusion process. Followed by the manufacture of tensile test specimen and tested its tensile strength with universal test machine 100kN Tensilon RTF 2410, at room temperature with constant crosshead speed. From tensile test results using single and double layers showed that double mesh-peel ply can increase tensile strength 14% and Young modulus 17%.

Modeling the VARTM Composite Manufacturing Process

NASA Technical Reports Server (NTRS)

Song, Xiao-Lan; Loos, Alfred C.; Grimsley, Brian W.; Cano, Roberto J.; Hubert, Pascal

2004-01-01

A comprehensive simulation model of the Vacuum Assisted Resin Transfer Modeling (VARTM) composite manufacturing process has been developed. For isothermal resin infiltration, the model incorporates submodels which describe cure of the resin and changes in resin viscosity due to cure, resin flow through the reinforcement preform and distribution medium and compaction of the preform during the infiltration. The accuracy of the model was validated by measuring the flow patterns during resin infiltration of flat preforms. The modeling software was used to evaluate the effects of the distribution medium on resin infiltration of a flat preform. Different distribution medium configurations were examined using the model and the results were compared with data collected during resin infiltration of a carbon fabric preform. The results of the simulations show that the approach used to model the distribution medium can significantly effect the predicted resin infiltration times. Resin infiltration into the preform can be accurately predicted only when the distribution medium is modeled correctly.

Nontoxic Resins Advance Aerospace Manufacturing

NASA Technical Reports Server (NTRS)

2009-01-01

The 2008 NASA Commercial Invention of the Year, PETI-330, is a polyimide matrix resin that performs well at high temperatures and is easily processed into composites in a simple, short curing cycle. Invented by scientists at Langley Research Center, PETI-330 is now licensed to Ube Industries, based in Japan with its American headquarters in New York. In addition to being durable and lightweight, the resin is also nontoxic, which makes it safe for workers to handle. PETI-330 was created specifically for heat-resistant composites formed with resin transfer molding and resin infusion, which formerly could only be used with low temperature resin systems.

Comparison of resin film infusion, resin transfer molding, and consolidation of textile preforms for primary aircraft structure

NASA Technical Reports Server (NTRS)

Suarez, J.; Dastin, S.

1992-01-01

Under NASA's Novel Composites for Wing and Fuselage Applications (NCWFA) Program, Grumman is developing innovative design concepts and cost-effective fabrication processes for damage-tolerant primary structures that can perform at a design ultimate strain level of 6000 micro-inch/inch. Attention has focused on the use of textile high-performance fiber-reinforcement concepts that provide improved damage tolerance and out-of-plane load capability, low-cost resin film infusion (RFI) and resin transfer molding (RTM) processes, and thermoplastic forming concepts. The fabrication of wing 'Y' spars by four different materials/processes methods is described: 'Y' spars fabricated using IM7 angle interlock 0/90 deg woven preforms with +/- 45 deg plies stitched with Toray high-strength graphite thread and processed using RFI and 3501-6 epoxy; 'Y' spars fabricated using G40-800 knitted/stitched preforms and processed using RFI and 3501-6 epoxy; 'Y' spars fabricated using G40-800 knitted/stitched preforms and processed using RTM and Tactix 123/H41 epoxy; and 'Y' spars fabricated using AS4(6k)/PEEK 150-g commingled angle interlock 0/90 deg woven preforms with +/- 45 deg commingled plies stitched using high-strength graphite thread and processed by consolidation. A comparison of the structural efficiency, processability, and projected acquisition cost of these representative spars is presented.

Reactivity study on thermal cracking of vacuum residues

NASA Astrophysics Data System (ADS)

León, A. Y.; Díaz, S. D.; Rodríguez, R. C.; Laverde, D.

2016-02-01

This study focused on the process reactivity of thermal cracking of vacuum residues from crude oils mixtures. The thermal cracking experiments were carried out under a nitrogen atmosphere at 120psi between 430 to 500°C for 20 minutes. Temperature conditions were established considering the maximum fractional conversion reported in tests of thermogravimetry performed in the temperature range of 25 to 600°C, with a constant heating rate of 5°C/min and a nitrogen flow rate of 50ml/min. The obtained products were separated in to gases, distillates and coke. The results indicate that the behaviour of thermal reactivity over the chemical composition is most prominent for the vacuum residues with higher content of asphaltenes, aromatics, and resins. Finally some correlations were obtained in order to predict the weight percentage of products from its physical and chemical properties such as CCR, SARA (saturates, aromatics, resins, asphaltenes) and density. The results provide new knowledge of the effect of temperature and the properties of vacuum residues in thermal conversion processes.

Homogeneous Liquid Phase Transfer of Graphene Oxide into Epoxy Resins.

PubMed

Amirova, Lyaysan; Surnova, Albina; Balkaev, Dinar; Musin, Delus; Amirov, Rustem; Dimiev, Ayrat M

2017-04-05

The quality of polymer composite materials depends on the distribution of the filler in the polymer matrix. Due to the presence of the oxygen functional groups, graphene oxide (GO) has a strong affinity to epoxy resins, providing potential opportunity for the uniform distribution of GO sheets in the matrix. Another advantage of GO over its nonoxidized counterpart is its ability to exfoliate to single-atomic-layer sheets in water and in some organic solvents. However, these advantages of GO have not yet been fully realized due to the lack of the methods efficiently introducing GO into the epoxy resin. Here we develop a novel homogeneous liquid phase transfer method that affords uniform distribution, and fully exfoliated condition of GO in the polymer matrix. The most pronounced alteration of properties of the cured composites is registered at the 0.10%-0.15% GO content. Addition of as little as 0.10% GO leads to the increase of the Young's modulus by 48%. Moreover, we demonstrate successful introduction of GO into the epoxy matrix containing an active diluent-modifier; this opens new venues for fabrication of improved GO-epoxy-modifier composites with a broad range of predesigned properties. The experiments done on reproducing the two literature methods, using alternative GO introduction techniques, lead to either decrease or insignificant increase of the Young's modulus of the resulting GO-epoxy composites.

Stability analysis of electrical powered wheelchair-mounted robotic-assisted transfer device.

PubMed

Wang, Hongwu; Tsai, Chung-Ying; Jeannis, Hervens; Chung, Cheng-Shiu; Kelleher, Annmarie; Grindle, Garrett G; Cooper, Rory A

2014-01-01

The ability of people with disabilities to live in their homes and communities with maximal independence often hinges, at least in part, on their ability to transfer or be transferred by an assistant. Because of limited resources and the expense of personal care, robotic transfer assistance devices will likely be in great demand. An easy-to-use system for assisting with transfers, attachable to electrical powered wheelchairs (EPWs) and readily transportable, could have a significant positive effect on the quality of life of people with disabilities. We investigated the stability of our newly developed Strong Arm, which is attached and integrated with an EPW to assist with transfers. The stability of the system was analyzed and verified by experiments applying different loads and using different system configurations. The model predicted the distributions of the system's center of mass very well compared with the experimental results. When real transfers were conducted with 50 and 75 kg loads and an 83.25 kg dummy, the current Strong Arm could transfer all weights safely without tip-over. Our modeling accurately predicts the stability of the system and is suitable for developing better control algorithms to enhance the safety of the device.

Post-Vacuum-Assisted Stereotactic Core Biopsy Clip Displacement: A Comparison Between Commercially Available Clips and Surgical Clip.

PubMed

Yen, Peggy; Dumas, Sandra; Albert, Arianne; Gordon, Paula

2018-02-01

The placement of localization clips following percutaneous biopsy is a standard practice for a variety of situations. Subsequent clip displacement creates challenges for imaging surveillance and surgical planning, and may cause confusion amongst radiologists and between surgeons and radiologists. Many causes have been attributed for this phenomenon including the commonly accepted "accordion effect." Herein, we investigate the performance of a low cost surgical clip system against 4 commercially available clips. We retrospectively reviewed 2112 patients who underwent stereotactic vacuum-assisted core biopsy followed by clip placement between January 2013 and June 2016. The primary performance parameter compared was displacement >10 mm following vacuum-assisted stereotactic core biopsy. Within the group of clips that had displaced, the magnitude of displacement was compared. There was a significant difference in displacement among the clip types (P < .0001) with significant pairwise comparisons between pediatric surgical clips and SecureMark (38% vs 28%; P = .001) and SenoMark (38% vs 27%; P = .0001) in the proportion displaced. The surgical clips showed a significant magnitude of displacement of approximately 25% greater average distance displaced. As a whole, the commercial clips performed better than the surgical clip after stereotactic vacuum-assisted core biopsy suggesting the surrounding outer component acts to anchor the central clip and minimizes clip displacement. The same should apply to tomosynthesis-guided biopsy. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

The effects of aircraft fuel and fluids on the strength properties of Resin Transfer Molded (RTM) composites

NASA Technical Reports Server (NTRS)

Falcone, Anthony; Dow, Marvin B.

1993-01-01

The resin transfer molding (RTM) process offers important advantages for cost-effective composites manufacturing, and consequently has become the subject of intense research and development efforts. Several new matrix resins have been formulated specifically for RTM applications in aircraft and aerospace vehicles. For successful use on aircraft, composite materials must withstand exposure to the fluids in common use. The present study was conducted to obtain comparative screening data on several state-ofthe-art RTM resins after environmental exposures were performed on RTM composite specimens. Four graphite/epoxy composites and one graphite/bismaleimide composite were tested; testing of two additional graphite epoxy composites is in progress. Zero-deg tension tests were conducted on specimens machined from eight-ply (+45-deg, -45-deg) laminates, and interlaminar shear tests were conducted on 32-ply 0-deg laminate specimens. In these tests, the various RTM resins demonstrated widely different strengths, with 3501-6 epoxy being the strongest. As expected, all of the matrix resins suffered severe strength degradation from exposure to methylene chloride (paint stripper). The 3501-6 epoxy composites exhibited about a 30 percent drop in tensile strength in hot, wet tests. The E905-L epoxy exhibited little loss of tensile strength (less than 8 percent) after exposure to water. The CET-2 and 862 epoxies as well as the bismaleimide exhibited reduced strengths at elevated temperature after exposure to oils and fuel. In terms of the percentage strength reductions, all of the RTM matrix resins compared favorably with 3501-6 epoxy.

Development of a low-cost, modified resin transfer molding process using elastomeric tooling and automated preform fabrication

NASA Technical Reports Server (NTRS)

Doane, William J.; Hall, Ronald G.

1992-01-01

This paper describes the design and process development of low-cost structural parts made by a modified resin transfer molding process. Innovative application of elastomeric tooling to increase laminate fiber volume and automated forming of fiber preforms are discussed, as applied to fabrication of a representative section of a cruise missile fuselage.

Radiative heat transfer exceeding the blackbody limit between macroscale planar surfaces separated by a nanosize vacuum gap

NASA Astrophysics Data System (ADS)

Bernardi, Michael P.; Milovich, Daniel; Francoeur, Mathieu

2016-09-01

Using Rytov's fluctuational electrodynamics framework, Polder and Van Hove predicted that radiative heat transfer between planar surfaces separated by a vacuum gap smaller than the thermal wavelength exceeds the blackbody limit due to tunnelling of evanescent modes. This finding has led to the conceptualization of systems capitalizing on evanescent modes such as thermophotovoltaic converters and thermal rectifiers. Their development is, however, limited by the lack of devices enabling radiative transfer between macroscale planar surfaces separated by a nanosize vacuum gap. Here we measure radiative heat transfer for large temperature differences (~120 K) using a custom-fabricated device in which the gap separating two 5 × 5 mm2 intrinsic silicon planar surfaces is modulated from 3,500 to 150 nm. A substantial enhancement over the blackbody limit by a factor of 8.4 is reported for a 150-nm-thick gap. Our device paves the way for the establishment of novel evanescent wave-based systems.

Fluid Structure Interaction Effects on Composites Under Low Velocity Impact

DTIC Science & Technology

2012-06-01

Nanotubes ( MWCNTs ) and the second had no reinforcements at the interface layer in front of the pre-cracks. Output from both tests was recorded using...these samples were tested. The first was reinforced with Multi-Walled Carbon Nanotubes ( MWCNTs ) and the second had no reinforcements at the interface...Ethyl Ketone Peroxide MWCNT Multi-Walled Carbon Nanotube VARTM Vacuum-Assisted Resin Transfer Molding xiv THIS PAGE INTENTIONALLY LEFT BLANK

Ultrasound-assisted extraction coupled with under vacuum distillation of flavour compounds from spearmint (carvone-rich) plants: Comparison with conventional hydrodistillation.

PubMed

Da Porto, Carla; Decorti, Deborha

2009-08-01

Ultrasonically assisted extraction of flavour compounds from different varieties of Mentha spicata, using 70% ethanol, have been carried out for 5, 10 and 15min and coupled with under vacuum distillation. The ultrasound distilled extracts have been analysed by GC-MS and compared with essential oils obtained by hydrodistillation. The results have showed that ultrasonically assisted extraction in combination with under vacuum distillation have provided extracts with higher flavouring strength due to the increased concentration of desirable oxygenated compounds (from 5 to 8 times) compared with hydrodistillation. Extraction yields of flavour volatiles have been calculated giving a range 0.04-0.13% by ultrasound and 0.01-0.02% by hydrodistillation.

Vacuum-sealed microcavity formed from suspended graphene by using a low-pressure dry-transfer technique

NASA Astrophysics Data System (ADS)

Takahashi, K.; Ishida, H.; Sawada, K.

2018-01-01

We report the development of a microcavity drum sealed by suspended graphene. The drum is fabricated by using a low-pressure dry-transfer technique, which involves vacuum de-aeration between a graphene sheet and a substrate and raising the temperature to above the glass transition of the supporting poly(methyl methacrylate) film, which serves to increase the real contact area. The result is a suspended graphene sheet with a maximum diameter of 48.6 μm. The Raman spectrum of the suspended graphene has a 2D/G ratio of 1.79 and a few D peaks, which suggests that the material is high-quality single-layer graphene. The dry-transfer technique yields a vacuum-sealed microcavity drum 1.1 μm deep up to 4.5 μm in diameter. The Raman shift indicates that the suspended graphene is subjected to a tensile strain of 0.05%, which is attributed to the pressure difference between the evacuated cavity and the exterior gas.

High pressure reaction cell and transfer mechanism for ultrahigh vacuum spectroscopic chambers

NASA Astrophysics Data System (ADS)

Nelson, A. E.; Schulz, K. H.

2000-06-01

A novel high pressure reaction cell and sample transfer mechanism for ultrahigh vacuum (UHV) spectroscopic chambers is described. The design employs a unique modification of a commercial load-lock transfer system to emulate a tractable microreactor. The reaction cell has an operating pressure range of <1×10-4 to 1000 Torr and can be evacuated to UHV conditions to enable sample transfer into the spectroscopic chamber. Additionally, a newly designed sample holder equipped with electrical and thermocouple contacts is described. The sample holder is capable of resistive specimen heating to 400 and 800 °C with current requirements of 14 A (2 V) and 25 A (3.5 V), respectively. The design enables thorough material science characterization of catalytic reactions and the surface chemistry of catalytic materials without exposing the specimen to atmospheric contaminants. The system is constructed primarily from readily available commercial equipment allowing its rapid implementation into existing laboratories.

Drying based on temperature-detection-assisted control in microwave-assisted pulse-spouted vacuum drying.

PubMed

Cao, Xiaohuang; Zhang, Min; Qian, He; Mujumdar, Arun S

2017-06-01

An online temperature-detection-assisted control system of microwave-assisted pulse-spouted vacuum drying was newly developed. By using this system, temperature control can be automatically and continuously adjusted based on the detection of drying temperature and preset temperature. Various strategies for constant temperature control, linear temperature control and three-step temperature control were applied to drying carrot cubes. Drying kinetics and the quality of various temperature-controlled strategies online are evaluated for the new drying technology as well as its suitability as an alternative drying method. Drying time in 70 °C mode 1 had the shortest drying time and lowest energy consumption in all modes. A suitable colour, highest re-hydration ratio and fracture-hardness, and longest drying time occurred in 30-40-50 °C mode 3. The number of hot spots was reduced in 40-50-60 °C mode 3. Acceptable carrot snacks were obtained in 50-60-70 °C mode 3 and 70 °C mode 2. All temperature curves showed that the actual temperatures followed the preset temperatures appropriately. With this system, a linear temperature-controlled strategy and a three-step temperature-controlled strategy can improve product quality and heating non-uniformity compared to constant temperature control, but need greater energy consumption and longer drying time. A temperature-detection-assisted control system was developed for providing various drying strategies as a suitable alternative in making a snack product. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

A generalized analytical model for radiative transfer in vacuum thermal insulation of space vehicles

NASA Astrophysics Data System (ADS)

Krainova, Irina V.; Dombrovsky, Leonid A.; Nenarokomov, Aleksey V.; Budnik, Sergey A.; Titov, Dmitry M.; Alifanov, Oleg M.

2017-08-01

The previously developed spectral model for radiative transfer in vacuum thermal insulation of space vehicles is generalized to take into account possible thermal contact between a fibrous spacer and one of the neighboring aluminum foil layers. An approximate analytical solution based on slightly modified two-flux approximation for radiative transfer in a semi-transparent fibrous spacer is derived. It was shown that thermal contact between the spacer and adjacent foil may decrease significantly the quality of thermal insulation because of an increase in radiative flux to/from the opposite aluminum foil. Theoretical predictions are confirmed by comparison with new results of laboratory experiments.

A study of LC-39 cryogenic systems. Part 1: A study of the vacuum insulated transfer lines at Kennedy Space Center. Part 2: Cooldown pressure surges

NASA Technical Reports Server (NTRS)

Ludtke, P. R.; Voth, R. O.

1971-01-01

The vacuum liquid hydrogen and liquid oxygen transfer lines at Kennedy Space Center were studied to evaluate the feasibility of using a condensing gas such as CO2 inside the vacuum spaces to achieve a condensing-vacuum. The study indicates that at ambient temperature, a maximum vacuum hyphen space pressure of 4000 microns is acceptable for the LH2 transfer lines. In addition, the cooldown procedures for the 14-inch cross-country liquid oxygen line was studied using a simplified mathematical model. Preliminary cooldown times are presented for various heat leak rates to the line and for two vent configurations.

Advanced patient transfer assist device with intuitive interaction control.

PubMed

Humphreys, Heather C; Choi, Young Mi; Book, Wayne J

2017-10-24

This research aims to improve patient transfers by developing a new type of advanced robotic assist device. It has multiple actuated degrees of freedom and a powered steerable base to maximize maneuverability around obstacles. An intuitive interface and control strategy allows the caregiver to simply push on the machine in the direction of desired patient motion. The control integrates measurements of both force and proximity to mitigate any potential large collision forces and provides operators information about obstacles with a form of haptic feedback. Electro-hydraulic pump controlled actuation provides high force density for the actuation. Nineteen participants performed tests to compare transfer operations (transferring a 250-lb mannequin between a wheelchair, chair, bed, and floor) and interaction control of a prototype device with a commercially available patient lift. The testing included a time study of the transfer operations and subjective rating of device performance. The results show that operators perform transfer tasks significantly faster and rate performance higher using the prototype patient transfer assist device than with a current market patient lift. With further development, features of the new patient lift can help facilitate patient transfers that are safer, easier, and more efficient for caregivers.

Electron transfer from a carbon nanotube into vacuum under high electric fields

NASA Astrophysics Data System (ADS)

Filip, L. D.; Smith, R. C.; Carey, J. D.; Silva, S. R. P.

2009-05-01

The transfer of an electron from a carbon nanotube (CNT) tip into vacuum under a high electric field is considered beyond the usual one-dimensional semi-classical approach. A model of the potential energy outside the CNT cap is proposed in order to show the importance of the intrinsic CNT parameters such as radius, length and vacuum barrier height. This model also takes into account set-up parameters such as the shape of the anode and the anode-to-cathode distance, which are generically portable to any modelling study of electron emission from a tip emitter. Results obtained within our model compare well to experimental data. Moreover, in contrast to the usual one-dimensional Wentzel-Kramers-Brillouin description, our model retains the ability to explain non-standard features of the process of electron field emission from CNTs that arise as a result of the quantum behaviour of electrons on the surface of the CNT.

Vacuum-bag-only processing of composites

NASA Astrophysics Data System (ADS)

Thomas, Shad

Ultrasonic imaging in the C-scan mode in conjunction with the amplitude of the reflected signal was used to measure flow rates of an epoxy resin film penetrating through the thickness of single layers of woven carbon fabric. Assemblies, comprised of a single layer of fabric and film, were vacuum-bagged and ultrasonically scanned in a water tank during impregnation at 50°C, 60°C, 70°C, and 80°C. Measured flow rates were plotted versus inverse viscosity to determine the permeability in the thin film, non-saturated system. The results demonstrated that ultrasonic imaging in the C-scan mode is an effective method of measuring z-direction resin flow through a single layer of fabric. The permeability values determined in this work were consistent with permeability values reported in the literature. Capillary flow was not observed at the temperatures and times required for pressurized flow to occur. The flow rate at 65°C was predicted from the linear plot of flow rate versus inverse viscosity. The effects of fabric architecture on through-thickness flow rates during impregnation of an epoxy resin film were measured by ultrasonic imaging. Multilayered laminates comprised of woven carbon fabrics and epoxy films (prepregs) were fabricated by vacuum-bagging. Ultrasonic imaging was performed in a heated water tank (65°C) during impregnation. Impregnation rates showed a strong dependence on fabric architecture, despite similar areal densities. Impregnation rates are directly affected by inter-tow spacing and tow nesting, which depend on fabric architecture, and are indirectly affected by areal densities. A new method of predicting resin infusion rates in prepreg and resin film infusion processes was proposed. The Stokes equation was used to derive an equation to predict the impregnation rate of laminates as a function of fabric architecture. Flow rate data previously measured by ultrasound was analyzed with the new equation and the Kozeny-Carman equation. A fiber

Rheological characterization of geopolymer binder modified by organic resins

NASA Astrophysics Data System (ADS)

Cekalová, M.; Kovárík, T.; Rieger, D.

2017-01-01

The purpose of this study is going to investigate properties of alkali-activated powder (calcined kaoilinitic clay and granulated blast furnace slag) prepared as a geopolymer paste and modified by various amount of organic resin. Hybrid organic-inorganic binders were prepared as a mix of organic resin and geopolymer inorganic paste under vacuum conditions. The process of solidification was investigated by measurements of storage (G’) and loss modulus ( G’) in torsion. The measurement was conducted in oscillatory mode by constant strain of 0.01 %. This strain is set in linear visco-elastic region for minimization influence of paste structure. The effect of organic resin is presented and determined by changes of viscosity (‘n*), modules in torsion and tangent of loss angle (tan 8). Results indicate that addition of organic resin significantly affects the initial viscosity and hardening kinetics.

7 CFR 3560.259 - Transferring rental assistance.

Code of Federal Regulations, 2010 CFR

2010-01-01

... for a tenant who is moving due to displacement as a result of prepayment, liquidation, or a natural disaster. The tenant must begin using the rental assistance within 4 months of the transfer or the RA will...

7 CFR 3560.259 - Transferring rental assistance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... for a tenant who is moving due to displacement as a result of prepayment, liquidation, or a natural disaster. The tenant must begin using the rental assistance within 4 months of the transfer or the RA will...

7 CFR 3560.259 - Transferring rental assistance.

Code of Federal Regulations, 2013 CFR

2013-01-01

... for a tenant who is moving due to displacement as a result of prepayment, liquidation, or a natural disaster. The tenant must begin using the rental assistance within 4 months of the transfer or the RA will...

Control and reduction of peak temperature in self-curing resins.

PubMed

Schiavetti, R; DE Vico, G; Casucci, A; Covello, F; Ottria, L; Sannino, G; Barlattani, A

2009-07-01

INTRODUCTION.: The aim of this experimental study was to reduce the exothermic reaction during curing of the resins to cold. The significant exotherm generated by the reaction of polymerization of the resin curing involves many clinical complications including the high risk of necrosis against tooth. MATERIAL AND METHODS.: They were used four different types of self curing resins all based on methyl methacrylate, Jet Kit, Major Dentin, Dura Lay, Temporary Cold. The reaction of polymerization of the resins was done in Teflon pans and was monitored by a thermocouple which recorded the highest level reached by each temperature resin with and without additive. The polymerization reaction took place for each resin in the presence of an essential oil, the terpinolene, which acted as a "chain transfer" and different temperatures were recorded. RESULTS.: Resins Dura Lay and Jet kit showed a reduction of very high temperature in the presence of terpinolene, with a statistically significant difference compared to the same reaction without terpinolene Major resin dentin in the presence of the additive has reduced by 8.4°C peak temperature. Resin Temporary Cold has showed benefits with respect to peak temperature, but the reaction was much more 'consistent presence of the additive. DISCUSSION.: The system through which the chain transfer acts to lower the temperature of the reaction is that of chain transfer. Namely that interfere with the reaction of the polymer chains, by transferring these acrylic radicals are no longer active, ie, no longer able to bind to other monomer units, thus avoiding the excessive growth of macromolecules which are those that determine the temperature rise. This leads to the formation of more polymer chains with lower molecular weight.

Ice-assisted transfer of carbon nanotube arrays.

PubMed

Wei, Haoming; Wei, Yang; Lin, Xiaoyang; Liu, Peng; Fan, Shoushan; Jiang, Kaili

2015-03-11

Decoupling the growth and the application of nanomaterials by transfer is an important issue in nanotechnology. Here, we developed an efficient transfer technique for carbon nanotube (CNT) arrays by using ice as a binder to temporarily bond the CNT array and the target substrate. Ice makes it an ultraclean transfer because the evaporation of ice ensures that no contaminants are introduced. The transferred superaligned carbon nanotube (SACNT) arrays not only keep their original appearance and initial alignment but also inherit their spinnability, which is the most desirable feature. The transfer-then-spin strategy can be employed to fabricate patterned CNT arrays, which can act as 3-dimensional electrodes in CNT thermoacoustic chips. Besides, the flip-chipped CNTs are promising field electron emitters. Furthermore, the ice-assisted transfer technique provides a cost-effective solution for mass production of SACNTs, giving CNT technologies a competitive edge, and this method may inspire new ways to transfer other nanomaterials.

Wireless Integrated Microelectronic Vacuum Sensor System

NASA Technical Reports Server (NTRS)

Krug, Eric; Philpot, Brian; Trott, Aaron; Lawrence, Shaun

2013-01-01

NASA Stennis Space Center's (SSC's) large rocket engine test facility requires the use of liquid propellants, including the use of cryogenic fluids like liquid hydrogen as fuel, and liquid oxygen as an oxidizer (gases which have been liquefied at very low temperatures). These fluids require special handling, storage, and transfer technology. The biggest problem associated with transferring cryogenic liquids is product loss due to heat transfer. Vacuum jacketed piping is specifically designed to maintain high thermal efficiency so that cryogenic liquids can be transferred with minimal heat transfer. A vacuum jacketed pipe is essentially two pipes in one. There is an inner carrier pipe, in which the cryogenic liquid is actually transferred, and an outer jacket pipe that supports and seals the vacuum insulation, forming the "vacuum jacket." The integrity of the vacuum jacketed transmission lines that transfer the cryogenic fluid from delivery barges to the test stand must be maintained prior to and during engine testing. To monitor the vacuum in these vacuum jacketed transmission lines, vacuum gauge readings are used. At SSC, vacuum gauge measurements are done on a manual rotation basis with two technicians, each using a handheld instrument. Manual collection of vacuum data is labor intensive and uses valuable personnel time. Additionally, there are times when personnel cannot collect the data in a timely fashion (i.e., when a leak is detected, measurements must be taken more often). Additionally, distribution of this data to all interested parties can be cumbersome. To simplify the vacuum-gauge data collection process, automate the data collection, and decrease the labor costs associated with acquiring these measurements, an automated system that monitors the existing gauges was developed by Invocon, Inc. For this project, Invocon developed a Wireless Integrated Microelectronic Vacuum Sensor System (WIMVSS) that provides the ability to gather vacuum

Preform Characterization in VARTM Process Model Development

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Cano, Roberto J.; Hubert, Pascal; Loos, Alfred C.; Kellen, Charles B.; Jensen, Brian J.

2004-01-01

Vacuum-Assisted Resin Transfer Molding (VARTM) is a Liquid Composite Molding (LCM) process where both resin injection and fiber compaction are achieved under pressures of 101.3 kPa or less. Originally developed over a decade ago for marine composite fabrication, VARTM is now considered a viable process for the fabrication of aerospace composites (1,2). In order to optimize and further improve the process, a finite element analysis (FEA) process model is being developed to include the coupled phenomenon of resin flow, preform compaction and resin cure. The model input parameters are obtained from resin and fiber-preform characterization tests. In this study, the compaction behavior and the Darcy permeability of a commercially available carbon fabric are characterized. The resulting empirical model equations are input to the 3- Dimensional Infiltration, version 5 (3DINFILv.5) process model to simulate infiltration of a composite panel.

Creep of experimental short fiber-reinforced composite resin.

PubMed

Garoushi, Sufyan; Kaleem, Muhammad; Shinya, Akikazu; Vallittu, Pekka K; Satterthwaite, Julian D; Watts, David C; Lassila, Lippo V J

2012-01-01

The purpose of this study was to investigate the reinforcing effect of short E-glass fiber fillers oriented in different directions on composite resin under static and dynamic loading. Experimental short fiber-reinforced composite resin (FC) was prepared by mixing 22.5 wt% of short E-glass fibers, 22.5 wt% of resin, and 55 wt% of silane-treated silica fillers. Three groups of specimens (n=5) were tested: FC with isotropic fiber orientation, FC with anisotropic fiber orientation, and particulate-filled composite resin (PFC) as a control. Time-dependent creep and recovery were recorded. ANOVA revealed that after secondary curing in a vacuum oven and after storage in dry condition for 30 days, FC with isotropic fiber orientation (1.73%) exhibited significantly lower static creep value (p<0.05) than PFC (2.54%). For the different curing methods and storage conditions evaluated in this study, FC achieved acceptable static and dynamic creep values when compared to PFC.

Vacuum drying of apples (cv. Golden Delicious): drying characteristics, thermodynamic properties, and mass transfer parameters

NASA Astrophysics Data System (ADS)

Nadi, Fatemeh; Tzempelikos, Dimitrios

2018-01-01

In this work, apples of cv. Golden Delicious were cut into slices that were 5 and 7 mm thick and then vacuum dried at 50, 60 and 70 °C and pressure of 0.02 bar. The thin layer model drying kinetics was studied, and mass transfer properties, specifically effective moisture diffusivity and convective mass transfer coefficient, were evaluated using the Fick's equation of diffusion. Also, thermodynamic parameters of the process, i.e. enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG), were determined. Colour properties were evaluated as one of the important indicators of food quality and marketability. Determination of mass transfer parameters and thermodynamic properties of vacuum dried apple slices has not been discussed much in the literature. In conclusion, the Nadi's model fitted best the observed data that represent the drying process. Thermodynamic properties were determined based on the dependence of the drying constant of the Henderson and Pabis model on temperature, and it was concluded that the variation in drying kinetics depends on the energy contribution of the surrounding environment. The enthalpy and entropy diminished, while the Gibbs free energy increased with the increase of the temperature of drying; therefore, it was possible to verify that variation in the diffusion process in the apple during drying depends on energetic contributions of the environment. The obtained results showed that diffusivity increased for 69%, while the mass transfer coefficient increase was even higher, 75%, at the variation of temperature of 20 °C. The increase in the dimensionless Biot number was 20%.

Vacuum drying of apples (cv. Golden Delicious): drying characteristics, thermodynamic properties, and mass transfer parameters

NASA Astrophysics Data System (ADS)

Nadi, Fatemeh; Tzempelikos, Dimitrios

2018-07-01

In this work, apples of cv. Golden Delicious were cut into slices that were 5 and 7 mm thick and then vacuum dried at 50, 60 and 70 °C and pressure of 0.02 bar. The thin layer model drying kinetics was studied, and mass transfer properties, specifically effective moisture diffusivity and convective mass transfer coefficient, were evaluated using the Fick's equation of diffusion. Also, thermodynamic parameters of the process, i.e. enthalpy ( ΔH), entropy ( ΔS) and Gibbs free energy ( ΔG), were determined. Colour properties were evaluated as one of the important indicators of food quality and marketability. Determination of mass transfer parameters and thermodynamic properties of vacuum dried apple slices has not been discussed much in the literature. In conclusion, the Nadi's model fitted best the observed data that represent the drying process. Thermodynamic properties were determined based on the dependence of the drying constant of the Henderson and Pabis model on temperature, and it was concluded that the variation in drying kinetics depends on the energy contribution of the surrounding environment. The enthalpy and entropy diminished, while the Gibbs free energy increased with the increase of the temperature of drying; therefore, it was possible to verify that variation in the diffusion process in the apple during drying depends on energetic contributions of the environment. The obtained results showed that diffusivity increased for 69%, while the mass transfer coefficient increase was even higher, 75%, at the variation of temperature of 20 °C. The increase in the dimensionless Biot number was 20%.

Temperature rise in pulpal chamber during fabrication of provisional resinous crowns.

PubMed

Castelnuovo, J; Tjan, A H

1997-11-01

The heat generated during the exothermic polymerization reaction of autopolymerizing resinous materials and the heat generated by ultraviolet lamps during irradiation of photopolymerizing resinous materials could cause pulpal damage when a direct technique is used to fabricate provisional restorations. This could occur if temperature elevations overcome the physiological heat dissipating mechanisms of the dental-periodontal system. This in vitro study compared the rise in temperatures in the pulpal chamber during fabrication of provisional complete veneer crowns by direct method with different autopolymerizing and photopolymerizing resins. The effect of curing resinous crowns in different matrices, such as a polyvinyl siloxane impression and a vaccuum-formed polypropylene sheet, was also evaluated. The results demonstrated that the amount of heat generated during resin polymerization and transmitted to the pulpal chamber could be damaging to pulpal tissues including odontoblasts. When curing of provisional resinous crowns was performed in the polyvinyl siloxane impression, significantly lower temperatures were recorded compared with curing in the vacuum-formed polypropylene sheet. To prevent pulpal damage, effective cooling procedures are strongly recommended when directly fabricating resinous provisional crowns.

Matrix resin effects in composite delamination - Mode I fracture aspects

NASA Technical Reports Server (NTRS)

Hunston, Donald L.; Moulton, Richard J.; Johnston, Norman J.; Bascom, Willard D.

1987-01-01

A number of thermoset, toughened thermoset, and thermoplastic resin matrix systems were characterized for Mode I critical strain energy release rates, and their composites were tested for interlaminar critical strain energy release rates using the double cantilever beam method. A clear correlation is found between the two sets of data. With brittle resins, the interlaminar critical strain energy release rates are somewhat larger than the neat resin values due to a full transfer of the neat resin toughness to the composite and toughening mechanisms associated with crack growth. With tougher matrices, the higher critical strain energy release rates are only partially transferred to the composites, presumably because the fibers restrict the crack-tip deformation zones.

[The evolution of vacuum extraction in obstetrics].

PubMed

Nikolov, A

2010-01-01

Vacuum extraction is one of the methods for assisted vaginal delivery. In this article the evolution of vacuum extraction in obstetrics is been discussed. Historical facts and data from the invention up to state-of-the-art vacuum systems in modern obstetrics are presented.

Homogenate-assisted Vacuum-powered Bubble Extraction of Moso Bamboo Flavonoids for On-line Scavenging Free Radical Capacity Analysis.

PubMed

Sun, Yinnan; Yang, Kui; Cao, Qin; Sun, Jinde; Xia, Yu; Wang, Yinhang; Li, Wei; Ma, Chunhui; Liu, Shouxin

2017-07-11

A homogenate-assisted vacuum-powered bubble extraction (HVBE) method using ethanol was applied for extraction of flavonoids from Phyllostachys pubescens (P. pubescens) leaves. The mechanisms of homogenate-assisted extraction and vacuum-powered bubble generation were discussed in detail. Furthermore, a method for the rapid determination of flavonoids by HPLC was established. HVBE followed by HPLC was successfully applied for the extraction and quantification of four flavonoids in P. pubescens , including orientin, isoorientin, vitexin, and isovitexin. This method provides a fast and effective means for the preparation and determination of plant active components. Moreover, the on-line antioxidant capacity, including scavenging positive ion and negative ion free radical capacity of different fractions from the bamboo flavonoid extract was evaluated. Results showed that the scavenging DPPH ˙ free radical capacity of vitexin and isovitexin was larger than that of isoorientin and orientin. On the contrary, the scavenging ABTS⁺ ˙ free radical capacity of isoorientin and orientin was larger than that of vitexin and isovitexin.

Modification of fast-growing Chinese Fir wood with unsaturated polyester resin: Impregnation technology and efficiency

NASA Astrophysics Data System (ADS)

Ma, Qing; Zhao, Zijian; Yi, Songlin; Wang, Tianlong

In this study, Chinese Fir was impregnated with unsaturated polyester resin to enhance its properties. Samples 20 mm × 20 mm × 20 mm in size were split into different sections with epoxy resin and tinfoil and subjected to an impregnation experiment under various parameters. Vacuum degree was -0.04 MPa, -0.06 MPa or -0.08 MPa and vacuum duration was 15 min, 30 min, or 45 min. The results indicated that impregnation weight percent gain is linearly dependent on curing weight percent gain. Vacuum duration appears to have less influence on the curing weight percent gain than vacuum degree, and impregnation was most successful at the transverse section compared to other sections. The optimal impregnation parameters were 30 min modification under -0.08 MPa vacuum followed by 120 min at atmospheric pressure for samples 200 mm × 100 mm × 20 mm in size. Uneven distribution of weight percent gain and cracking during the curing process suggested that 30 min post-processing at -0.09 MPa vacuum was the most effective way to complete the impregnation process. The sample's bending strength and modulus of elasticity increased after impregnation treatment. Bending strength after impregnation without post-processing reached 112.85%, but reached 71.65% with vacuum-processing; modulus of elasticity improved 67.13% and 58.28% without and with post-processing, respectively.

Surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet for flashover withstanding characteristics improvement in vacuum

NASA Astrophysics Data System (ADS)

Chen, Sile; Wang, Shuai; Wang, Yibo; Guo, Baohong; Li, Guoqiang; Chang, Zhengshi; Zhang, Guan-Jun

2017-08-01

For enhancing the surface electric withstanding strength of insulating materials, epoxy resin (EP) samples are treated by atmospheric pressure plasma jet (APPJ) with different time interval from 0 to 300s. Helium (He) and tetrafluoromethane (CF4) mixtures are used as working gases with the concentration of CF4 ranging 0%-5%, and when CF4 is ∼3%, the APPJ exhibits an optimal steady state. The flashover withstanding characteristics of modified EP in vacuum are greatly improved under appropriate APPJ treatment conditions. The surface properties of EP samples are evaluated by surface roughness, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. It is considered that both physical and chemical effects lead to the enhancement of flashover strength. The physical effect is reflected in the increase of surface roughness, while the chemical effect is reflected in the graft of fluorine groups.

Green Preparation of Epoxy/Graphene Oxide Nanocomposites Using a Glycidylamine Epoxy Resin as the Surface Modifier and Phase Transfer Agent of Graphene Oxide.

PubMed

Tang, Xinlei; Zhou, Yang; Peng, Mao

2016-01-27

In studies of epoxy/graphene oxide (GO) nanocomposites, organic solvents are commonly used to disperse GO, and vigorous mechanical processes and complicated modification of GO are usually required, increasing the cost and hindering the development and application of epoxy nanocomposites. Here, we report a green, facile, and efficient method of preparing epoxy/GO nanocomposites. When triglycidyl para-aminophenol (TGPAP), a commercially available glycidyl amine epoxy resin with one tertiary amine group per molecule, is used as both the surface modifier and phase transfer agent of GO, GO can be directly and rapidly transferred from water to diglycidyl ether of bisphenol A and other types of epoxy resins by manual stirring under ambient conditions, whereas GO cannot be transferred to these epoxy resins in the absence of TGPAP. The interaction between TGPAP and GO and the effect of the TGPAP content on the dispersion of GO in the epoxy matrix were investigated systematically. Superior dispersion and exfoliation of GO nanosheets and remarkably improved mechanical properties, including tensile and flexural properties, toughness, storage modulus, and microhardness, of the epoxy/GO nanocomposites with a suitable amount of TGPAP were demonstrated. This method is organic-solvent-free and technically feasible for large-scale preparation of high-performance nanocomposites; it opens up new opportunities for exploiting the unique properties of graphene or even other nanofillers for a wide range of applications.

Ab Initio Analysis of Auger-Assisted Electron Transfer.

PubMed

Hyeon-Deuk, Kim; Kim, Joonghan; Prezhdo, Oleg V

2015-01-15

Quantum confinement in nanoscale materials allows Auger-type electron-hole energy exchange. We show by direct time-domain atomistic simulation and analytic theory that Auger processes give rise to a new mechanism of charge transfer (CT) on the nanoscale. Auger-assisted CT eliminates the renown Marcus inverted regime, rationalizing recent experiments on CT from quantum dots to molecular adsorbates. The ab initio simulation reveals a complex interplay of the electron-hole and charge-phonon channels of energy exchange, demonstrating a variety of CT scenarios. The developed Marcus rate theory for Auger-assisted CT describes, without adjustable parameters, the experimental plateau of the CT rate in the region of large donor-acceptor energy gap. The analytic theory and atomistic insights apply broadly to charge and energy transfer in nanoscale systems.

Performance of resin transfer molded multiaxial warp knit composites

NASA Technical Reports Server (NTRS)

Dexter, H. Benson; Hasko, Gregory H.

1993-01-01

Composite materials that are subjected to complex loads have traditionally been fabricated with multidirectionally oriented prepreg tape materials. Some of the problems associated with this type of construction include low delamination resistance, poor out-of-plane strength, and labor intensive fabrication processes. Textile reinforced composites with through-the-thickness reinforcement have the potential to solve some of these problems. Recently, a relatively new class of noncrimp fabrics designated as multiaxial warp knits have been developed to minimize some of the high cost and damage tolerance concerns. Multiple stacks of warp knit fabrics can be knitted or stitched together to reduce layup labor cost. The through-the-thickness reinforcement can provide significant improvements in damage tolerance and out-of-plane strength. Multilayer knitted/stitched preforms, in conjunction with resin transfer molding (RTM), offer potential for significant cost savings in fabrication of primary aircraft structures. The objectives of this investigation were to conduct RTM processing studies and to characterize the mechanical behavior of composites reinforced with three multiaxial warp knit fabrics. The three fabrics investigated were produced by Hexcel and Milliken in the United States, and Saerbeck in Germany. Two resin systems, British Petroleum E9O5L and 3M PR 500, were characterized for RTM processing. The performance of Hexcel and Milliken quasi-isotropic knitted fabrics are compared to conventional prepreg tape laminates. The performance of the Saerbeck fabric is compared to uniweave wing skin layups being investigated by Douglas Aircraft Company in the NASA Advanced Composites Technology (ACT) program. Tests conducted include tension, open hole tension, compression, open hole compression, and compression after impact. The effects of fabric defects, such as misaligned fibers and gaps between tows, on material performance are also discussed. Estimated material and labor

Advanced resin systems and 3D textile preforms for low cost composite structures

NASA Technical Reports Server (NTRS)

Shukla, J. G.; Bayha, T. D.

1993-01-01

Advanced resin systems and 3D textile preforms are being evaluated at Lockheed Aeronautical Systems Company (LASC) under NASA's Advanced Composites Technology (ACT) Program. This work is aimed towards the development of low-cost, damage-tolerant composite fuselage structures. Resin systems for resin transfer molding and powder epoxy towpreg materials are being evaluated for processability, performance and cost. Three developmental epoxy resin systems for resin transfer molding (RTM) and three resin systems for powder towpregging are being investigated. Various 3D textile preform architectures using advanced weaving and braiding processes are also being evaluated. Trials are being conducted with powdered towpreg, in 2D weaving and 3D braiding processes for their textile processability and their potential for fabrication in 'net shape' fuselage structures. The progress in advanced resin screening and textile preform development is reviewed here.

High Temperature Transfer Molding Resins: Preliminary Composite Properties of PETI-375

NASA Technical Reports Server (NTRS)

Connell, J. W.; Smith, J. G., Jr.; Hergenrother, P. M.; Criss, J. M., Jr.

2004-01-01

As part of an ongoing effort to develop materials for resin transfer molding (RTM) of high performance/high temperature composites, a new phenylethynyl containing imide designated as PETI-375 has been under evaluation. PETI-375 was prepared using 2,3,3 ,4 - biphenyltetracarboxylic dianhydride (a-BPDA), 1,3-bis(4-aminophenoxy)benzene and 2,2 - bis(trifluoromethyl)benzidine and endcapped with 4-phenylethynylphthalic anhydride. This material exhibited a stable melt viscosity of 0.1-0.4 Pa sec at 280 C. High quality, void-free laminates were fabricated by high temperature RTM using unsized T-650 carbon fabric and evaluated. After curing for 1 hour at 371 C, the laminates exhibited a glass transition temperature of approx. 375 C by thermomechanical analysis. The laminates were essentially void and microcrack free as evidenced by optical microscopic examination. The chemistry, physical, and composite properties of PETI-375 will be discussed.

Nonlinear feedback guidance law for aero-assisted orbit transfer maneuvers

NASA Technical Reports Server (NTRS)

Menon, P. K. A.

1992-01-01

Aero-assisted orbit transfer vehicles have the potential for significantly reducing the fuel requirements in certain classes of orbit transfer operations. Development of a nonlinear feedback guidance law for performing aero-assisted maneuvers that accomplish simultaneous change of all the orbital elements with least vehicle acceleration magnitude is discussed. The analysis is based on a sixth order nonlinear point-mass vehicle model with lift, bank angle, thrust and drag modulation as the control variables. The guidance law uses detailed vehicle aerodynamic and the atmosphere models in the feedback loop. Higher-order gravitational harmonics, planetary atmosphere rotation and ambient winds are included in the formulation. Due to modest computational requirements, the guidance law is implementable on-board an orbit transfer vehicle. The guidance performance is illustrated for three sets of boundary conditions.

High pressure-assisted transfer of ultraclean chemical vapor deposited graphene

NASA Astrophysics Data System (ADS)

Chen, Zhiying; Ge, Xiaoming; Zhang, Haoran; Zhang, Yanhui; Sui, Yanping; Yu, Guanghui; Jin, Zhi; Liu, Xinyu

2016-03-01

We develop a high pressure-assisted (approximately 1000 kPa) transfer method to remove polymer residues and effectively reduce damages on the surface of graphene. By introducing an ethanol pre-dehydration technique and optimizing temperature, the graphene surface becomes nearly free of residues, and the quality of graphene is improved obviously when temperature reaches 140 °C. The graphene obtained using the high pressure-assisted transfer method also exhibits excellent electrical properties with an average sheet resistance of approximately 290 Ω/sq and a mobility of 1210 cm2/V.s at room temperature. Sheet resistance and mobility are considerably improved compared with those of the graphene obtained using the normal wet transfer method (average sheet resistance of approximately 510 ohm/sq and mobility of 750 cm2/V.s).

Characterization of the homologs of flerovium with crown ether based extraction chromatography resins: studies in nitric acid

DOE PAGES

Despotopulos, John D.; Kmak, Kelly N.; Gharibyan, Narek; ...

2016-09-17

Eichrom’s Pb resin, a crown-ether-based extraction chromatography resin, was characterized for separation of the flerovium (Fl) homologs, Pb and Sn. Batch uptake of Pb(II) and Sn(IV) radionuclides was determined from an HNO 3 matrix. Pb(II) was strongly retained on the resin at all HNO 3 concentrations, while Sn(IV) showed no uptake. Extraction kinetics for Pb(II) were examined and show suitable uptake on the second time scale. Here, separation methods for the isolation of individual homologs, Pb(II) and Sn(IV), have been established using 2 mL pre-packed vacuum flow Pb resin columns.

Materials for Heated Head Automated Thermoplastic Tape Placement

NASA Technical Reports Server (NTRS)

Jensen, Brian J.; Kinney, Megan C.; Cano, Roberto J.; Grimsley, Brian W.

2012-01-01

NASA Langley Research Center (LaRC) is currently pursuing multiple paths to develop out of autoclave (OOA) polymeric composite materials and processes. Polymeric composite materials development includes the synthesis of new and/or modified thermosetting and thermoplastic matrix resins designed for specific OOA processes. OOA processes currently under investigation include vacuum bag only (VBO) prepreg/composite fabrication, resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM) and heated head automated thermoplastic tape placement (HHATP). This paper will discuss the NASA Langley HHATP facility and capabilities and recent work on characterizing thermoplastic tape quality and requirements for quality part production. Samples of three distinct versions of APC-2 (AS4/PEEK) thermoplastic dry tape were obtained from two materials vendors, TENCATE, Inc. and CYTEC Engineered Materials** (standard grade and an experimental batch). Random specimens were taken from each of these samples and subjected to photo-microscopy and surface profilometry. The CYTEC standard grade of APC-2 tape had the most voids and splits and the highest surface roughness and/or waviness. Since the APC-2 tape is composed of a thermoplastic matrix, it offers the flexibility of reprocessing to improve quality, and thereby improve final quality of HHATP laminates. Discussions will also include potential research areas and future work that is required to advance the state of the art in the HHATP process for composite fabrication.

Integrated Cooling-Vacuum-Assisted Non-Fractional 1540 nm Erbium:Glass Laser is Effective in Treating Acne Scars.

PubMed

Politi, Yael; Levi, Assi; Lapidoth, Moshe

2016-11-01

Acne scars are a common result of in ammatory acne, affecting many patients worldwide. Among which, atrophic scars are the most prevalent form, presenting as dermal depressions caused by inflammatory degeneration of dermal collagen. Mid-infrared laser skin interaction is characterized by its modest absorption in water and nite penetration to the mid-dermis. Since collagen is a desirable laser target, 1540-nm wavelength is amenable for collagen remodeling within the depressed area of atrophic scars. To evaluate the safety and efficacy of acne scars treatment using an integrated cooling-vacuum-assisted 1540 nm Erbium: Glass Laser. This interventional prospective study included 25 volunteers (10 men, 15 women) with post acne atrophic scars. Patients were treated with a mid-infrared non-fractional 1540 nm Er:Glass laser (Alma Lasers Ltd. Caesarea, Israel) with integrat- ed cooling- vacuum assisted technology. Acne scars were exposed to 3 stacked laser pulses (400-600 mJ/pulse, 4 mm spot size, frequency of 3 Hz). Patients underwent 3-6 treatment sessions with a 2-3 week interval and were followed-up 1 month and 3 months after the last treatment. Clinical photographs were taken by high resolution digital camera before and after treatment. Clinical evaluation was performed by two independent dermatologists and results were graded on a scale of 0 (exacerbation) to 4 (76%-100% improvement). Patients' and physicians' satisfaction were also recorded (on a 1-5 scale). Pain perception and adverse effects were evaluated as well. Almost all patients (24/25) demonstrated a moderate to significant improvement. Average improvement was 3.9 and 4.1 points on the quartile scale used for outcome assessment 1 and 3 months following the last session, respectively. Patient satisfaction rate was 4.2. Side effects were minimal and transient: erythema, mild transient vesicles, and mild pain or inconvenience. CONCLUSION Cooling-Vacuum-Assisted mid-infrared non-fractional Er:Glass 1540 nm laser

Preliminary evaluation of Glass Resin materials for solar cell cover use

NASA Technical Reports Server (NTRS)

Marsik, S. J.; Swartz, C. K.; Baraona, C. R.

1978-01-01

The glass resins were deposited by several techniques on 200 micron thick cells and on 50 microns thick wafers. The covered cells were exposed to ultraviolet light in vacuum to an intensity of 10 UV energy-equivalent solar constants at air mass zero for 728 hr. The exposure was followed by a single long thermal cycle from ambient temperature to -150 C. Visual inspection of the samples indicated that all samples had darkened to varying degrees. The loss in short-circuit current was found to range from 8 to 24%, depending on the resin formulation. In another test over 40 glass resin-coated silicon wafers withstood 15 thermal cycles from 100 to-196 C in one or more of the thicknesses tested. Several of the resin-coated wafers were tested at 65 C and 90% relative humidity for 170 hr. No change in physical appearance was detected.

Magnetically Suspended Linear Pulse Motor for Semiconductor Wafer Transfer in Vacuum Chamber

NASA Technical Reports Server (NTRS)

Moriyama, Shin-Ichi; Hiraki, Naoji; Watanabe, Katsuhide; Kanemitsu, Yoichi

1996-01-01

This paper describes a magnetically suspended linear pulse motor for a semiconductor wafer transfer robot in a vacuum chamber. The motor can drive a wafer transfer arm horizontally without mechanical contact. In the construction of the magnetic suspension system, four pairs of linear magnetic bearings for the lift control are used for the guidance control as well. This approach allows us to make the whole motor compact in size and light in weight. The tested motor consists of a double-sided stator and a transfer arm with a width of 50 mm and a total length of 700 mm. The arm, like a ladder in shape, is designed as the floating element with a tooth width of 4 mm (a tooth pitch of 8 mm). The mover mass is limited to about 1.6 kg by adopting such an arm structure, and the ratio of thrust to mover mass reaches to 3.2 N/kg under a broad air gap (1 mm) between the stator teeth and the mover teeth. The performance testing was carried out with a transfer distance less than 450 mm and a transfer speed less than 560 mm/s. The attitude of the arm was well controlled by the linear magnetic bearings with a combined use, and consequently the repeatability on the positioning of the arm reached to about 2 micron. In addition, the positioning accuracy was improved up to about 30 micron through a compensation of the 128-step wave current which was used for the micro-step drive with a step increment of 62.5 micron.

Histology after lumpectomy in women with epithelial atypia on stereotactic vacuum-assisted breast biopsy.

PubMed

Graesslin, O; Antoine, M; Chopier, J; Seror, J Y; Flahault, A; Callard, P; Daraï, E; Uzan, S

2010-02-01

Large-core needle biopsy of the breast (LCNB) and vacuum-assisted breast biopsy (VABB) are widely used as alternatives to open surgical biopsy (OSB) for initial diagnosis of mammographic abnormalities. Between 18% and 80% of cases in which such specimens show atypical lobular hyperplasia (ALH) or atypical ductal hyperplasia (ADH) are found to be malignant at surgery. From 1999 to 2005, 68 women with mammographic abnormalities were sampled by stereotactic VABB and presented atypical epithelial hyperplasia. Immunohistochemical staining with anti-cytokeratin 5/6 and anti-E-cadherin antibodies was performed. All women underwent a lumpectomy. Clinical, radiological or histological factors predictive of the risk of finding malignancy at surgery were sought. VABB initially showed 28 cases of ADH, 32 cases of ALH, one case of flat epithelial atypia, five cases of mixed atypia, and two cases of Lobular Carcinoma In Situ (LCIS). After slide review with immunohistochemical staining, two cases of ADH were reclassified as simple hyperplasia and two cases of ALH were reclassified as mixed atypia. Seven lesions (10.3%) that appeared to be benign on VABB were found to be malignant on OSB (Ductal Carcinoma In Situ (DCIS) in six cases and invasive ductal carcinoma in one case). ADH was the only predictive factor of malignancy on OSB (p=0.04 versus ALH). ADH diagnosed by vacuum-assisted breast biopsy frequently corresponds to cancer on open surgical biopsy. Surgical excision of all breast lesions containing atypical hyperplasia on percutaneous biopsy can be recommended. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Magnet Assisted Composite Manufacturing: A Flexible New Technique for Achieving High Consolidation Pressure in Vacuum Bag/Lay-Up Processes.

PubMed

Pishvar, Maya; Amirkhosravi, Mehrad; Altan, M Cengiz

2018-05-17

This work demonstrates a protocol to improve the quality of composite laminates fabricated by wet lay-up vacuum bag processes using the recently developed magnet assisted composite manufacturing (MACM) technique. In this technique, permanent magnets are utilized to apply a sufficiently high consolidation pressure during the curing stage. To enhance the intensity of the magnetic field, and thus, to increase the magnetic compaction pressure, the magnets are placed on a magnetic top plate. First, the entire procedure of preparing the composite lay-up on a magnetic bottom steel plate using the conventional wet lay-up vacuum bag process is described. Second, placement of a set of Neodymium-Iron-Boron permanent magnets, arranged in alternating polarity, on the vacuum bag is illustrated. Next, the experimental procedures to measure the magnetic compaction pressure and volume fractions of the composite constituents are presented. Finally, methods used to characterize microstructure and mechanical properties of composite laminates are discussed in detail. The results prove the effectiveness of the MACM method in improving the quality of wet lay-up vacuum bag laminates. This method does not require large capital investment for tooling or equipment and can also be used to consolidate geometrically complex composite parts by placing the magnets on a matching top mold positioned on the vacuum bag.

Approaches to Design and Evaluation of Sandwich Composites

NASA Technical Reports Server (NTRS)

Shivakumar, Kunigal; Raju, I. S. (Technical Monitor); Ambur, D. (Technical Monitor)

2001-01-01

This report describes research during the period June 15, 1997 to October 31, 2000. This grant yielded a low cast manufacturing of composite sandwich structures technology and characterization interfacial and subinterfacial cracks in foam core sandwich panels. The manufacturing technology is called the vacuum assisted resin transfer (VARTM). The VARTM is suitable for processing composite materials both at ambient and elevated temperatures and of unlimited component size. This technology has been successfully transferred to a small business fiber preform manufacturing company 3TEX located in Cary, North Carolina. The grant also supported one Ph.D, one M.S and a number of under graduate students, and nine publications and Presentations.

Can Vacuum Assisted Venous Drainage be Achieved using a Roller Pump in an Emergency? A Pilot Study using Neonatal Circuitry

PubMed Central

Hill, S. L.; Holt, D. W.

2007-01-01

Abstract: There has been much advancement in perfusion technology over its 50 years of progression. One of these techniques is vacuum-assisted venous drainage (VAVD). Many perfusionists augment venous drainage using VAVD, typically from a wall vacuum source. This study explores alternates to providing VAVD if the wall vacuum fails. In two porcine laboratories, ∼36 in. of 3/16-in. tubing was connected to a sucker return port and placed into the roller head next to the arterial pump. The vacuum was monitored with a DLP pressure monitoring system (Medtronic). This system was connected to small-bore tubing and attached to a stopcock on top of the reservoir. The vacuum was regulated using another stopcock connected to a non-filtered luer lock port on top of the reservoir or by a segment of 3 × 0.25-in.-diameter tubing attached to the vent port with a c-clamp. Vacuum drainage was achieved, ranging from −18 mmHg to −71 mmHg by manipulating the stopcock or c-clamp. Changes in venous drainage were seen by volume fluctuations in the venous reservoir. The vacuum was adjusted to account for dramatic changes. Augmented venous drainage using a roller pump can be achieved successfully during cardiopulmonary bypass (CPB). This method of active drainage can be used in lieu of wall suction or during times of emergency if wall suction fails. PMID:18293812

Pilot study of a novel vacuum-assisted method for decellularization of tracheae for clinical tissue engineering applications.

PubMed

Lange, P; Greco, K; Partington, L; Carvalho, C; Oliani, S; Birchall, M A; Sibbons, P D; Lowdell, M W; Ansari, T

2017-03-01

Tissue engineered tracheae have been successfully implanted to treat a small number of patients on compassionate grounds. The treatment has not become mainstream due to the time taken to produce the scaffold and the resultant financial costs. We have developed a method for decellularization (DC) based on vacuum technology, which when combined with an enzyme/detergent protocol significantly reduces the time required to create clinically suitable scaffolds. We have applied this technology to prepare porcine tracheal scaffolds and compared the results to scaffolds produced under normal atmospheric pressures. The principal outcome measures were the reduction in time (9 days to prepare the scaffold) followed by a reduction in residual DNA levels (DC no-vac: 137.8±48.82 ng/mg vs. DC vac 36.83±18.45 ng/mg, p<0.05.). Our approach did not impact on the collagen or glycosaminoglycan content or on the biomechanical properties of the scaffolds. We applied the vacuum technology to human tracheae, which, when implanted in vivo showed no significant adverse immunological response. The addition of a vacuum to a conventional decellularization protocol significantly reduces production time, whilst providing a suitable scaffold. This increases clinical utility and lowers production costs. To our knowledge this is the first time that vacuum assisted decellularization has been explored. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Monitoring in situ in real time of resin infusion for thermoset composite structures

NASA Astrophysics Data System (ADS)

Faci, A.; Wang, P.; Cochrane, C.; Koncar, V.

2017-10-01

The presented work investigates changes in electrical resistance of embedded sensory yarns as a method to monitor the resin flow front position and curing degree of resin during manufacturing of composite structures by vacuum infusion technology. The sensor concept is based on Piezo-resistive sensors integrated to the flax fabric, having almost identical propriety and dimensions as the flax threads used for the production of reinforcements. In the first time sensors have been characterized and first measures of the resin infusion have been realized in order to demonstrate the feasibility of the proposed approach. Then, the measures in real time were realized with fibrous sensors added to the flax fabric (green composites) to monitor the flow front of resin. A large amount of data recorded, filtered, examined, analysed and processed in order to understand and to optimize the infusion and polymerization process.

Vacuum infusion manufacturing and experimental characterization of Kevlar/epoxy composites

NASA Astrophysics Data System (ADS)

Ricciardi, M. R.; Giordano, M.; Langella, A.; Nele, L.; Antonucci, V.

2014-05-01

Epoxy/Kevlar composites have been manufactured by conventional Vacuum Infusion process and the Pulse Infusion technique. Pulse Infusion allows to control the pressure of the vacuum bag on the dry fiber reinforcement by using a proper designed pressure distributor that induces a pulsed transverse action and promotes the through thickness resin flow. The realized composite panel have been mechanically characterized by performing tensile and short beam shear tests according with the ASTM D3039 and ASTM D2344/D 2344M standard respectively in order to investigate the effect of Pulse Infusion on the tensile strength and ILSS.

Vacuum infusion manufacturing and experimental characterization of Kevlar/epoxy composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ricciardi, M. R.; Giordano, M.; Antonucci, V.

2014-05-15

Epoxy/Kevlar composites have been manufactured by conventional Vacuum Infusion process and the Pulse Infusion technique. Pulse Infusion allows to control the pressure of the vacuum bag on the dry fiber reinforcement by using a proper designed pressure distributor that induces a pulsed transverse action and promotes the through thickness resin flow. The realized composite panel have been mechanically characterized by performing tensile and short beam shear tests according with the ASTM D3039 and ASTM D2344/D 2344M standard respectively in order to investigate the effect of Pulse Infusion on the tensile strength and ILSS.

Solution-assisted ultrafast transfer of graphene-based thin films for solar cells and humidity sensors.

PubMed

Sun, Jiawei; Xie, Xiao; Bi, Hengchang; Jia, Haiyang; Zhu, Chongyang; Wan, Neng; Huang, Jianqiu; Nie, Meng; Li, Dan; Sun, Litao

2017-03-01

Vacuum filtration enables the fabrication of large-area graphene-based membranes (GBMs), possessing a smoother surface than that by spray, spin coating or drop casting. However, due to the strong interaction with substrates, the separation of thin GBMs from the filter is problematic. Conventional stamping separation/transfer of graphene oxide (GO) thin films requires another substrate and pressing for >10 h, which may damage the delicate structure of the transfer substrates. Other methods require GO to be reduced on filters before separation, thus limiting the reduction methods. Inspired by a coagulation bath that enables rapid formation of ultrastrong GO fibers, we present an ultrafast (<1 min) and solution-assisted strategy to fabricate smooth and freestanding GO films. The diverse interfacial energy of hydrogen bonds also demonstrates another reason for the successful separation. The film thickness ranges from 45 nm to several micrometers. When used as a composite of counter electrodes in dye sensitized solar cells, it showed higher (8.58%) power conversion efficiency than its spin-(7.71%) and spray-coated (8.07%) counterparts. It also showed promising performance in capacitive humidity sensors. The capacitance varied by three orders of magnitude in the range of the relative humidity of 15%-95%. Therefore the strategy realizes an ultrafast and high-quality film production which is suitable for various applications.

Solution-assisted ultrafast transfer of graphene-based thin films for solar cells and humidity sensors

NASA Astrophysics Data System (ADS)

Sun, Jiawei; Xie, Xiao; Bi, Hengchang; Jia, Haiyang; Zhu, Chongyang; Wan, Neng; Huang, Jianqiu; Nie, Meng; Li, Dan; Sun, Litao

2017-03-01

Vacuum filtration enables the fabrication of large-area graphene-based membranes (GBMs), possessing a smoother surface than that by spray, spin coating or drop casting. However, due to the strong interaction with substrates, the separation of thin GBMs from the filter is problematic. Conventional stamping separation/transfer of graphene oxide (GO) thin films requires another substrate and pressing for >10 h, which may damage the delicate structure of the transfer substrates. Other methods require GO to be reduced on filters before separation, thus limiting the reduction methods. Inspired by a coagulation bath that enables rapid formation of ultrastrong GO fibers, we present an ultrafast (<1 min) and solution-assisted strategy to fabricate smooth and freestanding GO films. The diverse interfacial energy of hydrogen bonds also demonstrates another reason for the successful separation. The film thickness ranges from 45 nm to several micrometers. When used as a composite of counter electrodes in dye sensitized solar cells, it showed higher (8.58%) power conversion efficiency than its spin-(7.71%) and spray-coated (8.07%) counterparts. It also showed promising performance in capacitive humidity sensors. The capacitance varied by three orders of magnitude in the range of the relative humidity of 15%-95%. Therefore the strategy realizes an ultrafast and high-quality film production which is suitable for various applications.

Color stainability of CAD/CAM and nanocomposite resin materials.

PubMed

Acar, Ozlem; Yilmaz, Burak; Altintas, Subutay Han; Chandrasekaran, Indumathi; Johnston, William M

2016-01-01

The color stainability of recently introduced computer-assisted design/computer-assisted manufacturing (CAD/CAM) hybrid ceramic and resin nanoceramic is unknown. The purpose of this in vitro study was to compare the effect of coffee staining on the color of 3 different CAD/CAM restorative materials and a nanocomposite resin. Specimens from a hybrid dental ceramic (VITA Enamic), a resin nanoceramic (Lava Ultimate), a lithium disilicate glass ceramic (IPS e.max CAD), and a nanocomposite resin (Filtek Supreme Ultra Universal) were evaluated for color change due to thermocycling in coffee (n=5). Specimens 0.5 to 0.7 mm and 1 to 1.2 mm in thickness were thermocycled for 5000 cycles. CIEDE2000 color differences (ΔE00) due to thermocycling in coffee were calculated using the color coordinates obtained from a spectroradiometer. ANCOVA was used to analyze the color differences among the materials with thickness as the covariate. Significant differences at average thickness were analyzed with the Tukey-Kramer test. For color difference due to staining, thickness was a significant covariate (P<.001). Regarding the analysis of color differences, every pair of the tested materials was significantly different (P<.001). Least squares means of color differences (ΔE00) at mean thickness were 4.34 for the nanohybrid composite resin, 3.66 for the resin nanoceramic, 1.35 for the hybrid ceramic, and 0.43 for the lithium disilicate ceramic. When exposed to hot and cold coffee, the color change was beyond clinical acceptability for the tested resin nanoceramic and nanocomposite resin materials. The average color change of the hybrid ceramic was clinically perceivable over the tested thickness values. The color change of lithium disilicate ceramic was not clinically perceivable at any tested thickness. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Abdominal Subcutaneous Mass After Laser-Assisted Lipolysis and Immediate Multiple Treatments with a Dual-Wavelength Laser, Vacuum and Massage Device.

PubMed

Gentileschi, Stefano; Servillo, Maria; D'Ettorre, Marco; Salgarello, Marzia

2016-04-01

Body contouring by means of minimally invasive procedures is a growing trend. Current approaches to body contouring often involve a combination of surgical techniques (eg, laser-assisted liposuction) and a series of noninvasive device-based treatments aimed at accelerating recovery and improving aesthetic outcomes. In this case study, we describe a 38-year-old woman who presented with an abdominal-wall mass that resembled a tumor when assessed with magnetic resonance imaging. Twenty-six months before presenting to our office, the patient had undergone laser lipolysis and a series of treatments with a device that delivered dual-wavelength laser energy and vacuum-assisted massage. To address the patient's concerns, we removed the mass and performed abdominal dermolipectomy. No postoperative complications occurred, and the patient was highly satisfied with the aesthetic outcome. The results of histologic studies indicated that the mass was pseudocystic and fluid-filled, surrounded by a fibrous capsule, and characterized as a foreign-body granuloma. Further analysis is warranted regarding the safety of laser lipolysis without aspiration combined with a device delivering dual-wavelength laser energy and vacuum-assisted massage. 5 Risk. © 2015 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

Epoxy/Glass and Polyimide (LaRC(TradeMark) PETI-8)/Carbon Fiber Metal Laminates Made by the VARTM Process

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Loos, Alfred C.; Jensen, Brian J.; Britton, Sean M.; Tuncol, Goker; Long, Kai

2010-01-01

Recent work at NASA Langley Research Center (LaRC) has concentrated on developing new polyimide resin systems for advanced aerospace applications that can be processed without the use of an autoclave. Polyimide composites are very attractive for applications that require a high strength to weight ratio and thermal stability. Vacuum assisted resin transfer molding (VARTM) has shown the potential to reduce the manufacturing cost of composite structures. Fiber metal laminates (FML) made via this process with aluminum, glass fabric, and epoxy resins have been previously fabricated at LaRC. In this work, the VARTM process has been refined for epoxy/glass FMLs and extended to the fabrication of FM Ls with titanium/carbon fabric layers and a polyimide system developed at NASA, LARC(TradeMark) PETI-8. Resin flow pathways were introduced into the titanium foils to aid the infiltration of the polyimide resin. Injection temperatures in the range of 250-280 C were required to achieve the necessary VARTM viscosities (<10 Poise). Laminate quality and initial mechanical properties will be presented.

Cation exchange assisted binding-elution strategy for enzymatic synthesis of human milk oligosaccharides (HMOs).

PubMed

Zhu, Hailiang; Wu, Zhigang; Gadi, Madhusudhan Reddy; Wang, Shuaishuai; Guo, Yuxi; Edmunds, Garrett; Guan, Wanyi; Fang, Junqiang

2017-09-15

A cation exchange assisted binding-elution (BE) strategy for enzymatic synthesis of human milk oligosaccharides (HMOs) was developed. An amino linker was used to provide the cation ion under acidic condition which can be readily bound to cation exchange resin and then eluted off by saturated ammonium bicarbonate. Ammonium bicarbonate in the collections was easily removed by vacuum evaporation. This strategy circumvented the incompatible issue between glycosyltransferases and solid support or large polymers, and no purification was needed for intermediate products. With current approach, polyLacNAc backbones of HMOs and fucosylated HMOs were synthesized smoothly. Copyright © 2017 Elsevier Ltd. All rights reserved.

Early Conversion of External Fixation to Interlocked Nailing in Open Fractures of Both Bone Leg Assisted with Vacuum Closure (VAC) - Final Outcome

PubMed Central

Raj, Manish; Kumar, Sunil; Singh, Pulkesh; Kumar, Dinesh; Singh, Jasveer; Deep, Akash

2016-01-01

Introduction Management of compound grade III fractures of both bone leg includes external stabilization for long period, followed by various soft tissue coverage procedures. Primary interlocking of tibia had been also done with variable results. External fixation for long time without any bone loss often leads to infected nonunion, loss of reduction, pin tract infection and failure of fixation, primary interlocking in compound grade III fractures had shown high medullary infection rate. We managed all cases of compound grade III A/B fractures with primary external fixation, simultaneous wound management using vacuum assisted closure (VAC) followed by early conversion to interlocking within 2 weeks of fixator application. Aim To determine the effectiveness of vacuum assisted closure (VAC) for the early conversion of external fixator to definitive interlocking in open fractures of the both bone leg. Materials and Methods In current study we selected 84 cases of compound grade IIIA/B diaphyseal fractures of both bone leg during period of May 2010 to September 2013. We managed these cases by immediate debridement and application of external fixation followed by repeated debridement, application of vacuum assisted closure (VAC) and conversion to interlocking within two weeks. Results Out of 84 cases union was achieved in 80(95%) of cases with definitive tibial interlocking. Excellent to good result were obtained in 77(91.8%) of cases and fair to poor result seen in rest of 7(8.2%) of cases according to modified Ketenjian’s criteria. 5 out of these 7 poor result group cases were from Compound Grade III B group to start with. Deep infection rate in our series were 7% i.e. total 6 cases and 4 out of these were from compound Grade III B group to start with. Conclusion Vacuum assisted closure (VAC) give a good help for rapid closure of the wound and help in early conversion to definitive intramedullary nailing. Reamed nail could well be used in compound grade IIIA

Response of resin transfer molded (RTM) composites under reversed cyclic loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahfuz, H.; Haque, A.; Yu, D.

1996-01-01

Compressive behavior and the tension-compression fatigue response of resin transfer molded IM7 PW/PR 500 composite laminate with a circular notch have been studied. Fatigue damage characteristics have been investigated through the changes in the laminate strength and stiffness by gradually incrementing the fatigue cycles at a preselected load level. Progressive damage in the surface of the laminate during fatigue has been investigated using cellulose replicas. Failure mechanisms during static and cyclic tests have been identified and presented in detail. Extensive debonding of filaments and complete fiber bundle fracture accompanied by delamination were found to be responsible for fatigue failures, whilemore » fiber buckling, partial fiber fracture and delamination were characterized as the failure modes during static tests. Weibull analysis of the static, cyclic and residual tests have been performed and described in detail. Fractured as well as untested specimens were C-scanned, and the progressive damage growth during fatigue is presented. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) for the fractured specimen were also performed and the analysis of the failure behavior is presented.« less

Development of solvent-free offset ink using vegetable oil esters and high molecular-weight resin.

PubMed

Park, Jung Min; Kim, Young Han; Kim, Sung Bin

2013-01-01

In the development of solvent-free offset ink, the roles of resin molecular weight and used solvent on the ink performance were evaluated by examining the relationship between the various properties of resin and solvent and print quality. To find the best performing resin, the soy-oil fatty acid methyl ester (FAME) was applied to the five modified-phenolic resins having different molecular weights. It is found from the experimental results that the ink made of higher molecular weight and better solubility resin gives better printability and print quality. It is because larger molecular weight resin with better solubility gives higher rate of ink transfer. From the ink application of different esters to high molecular weight resin, the best printing performance was yielded from the soy-oil fatty acid butyl ester (FABE). It is due to its high kinematic viscosity resulting in the smallest change of ink transfer weight upon multiple number of printing, which improves the stability of ink quality.

Preliminary evaluation of glass resin materials for solar cell cover use. [on spacecraft

NASA Technical Reports Server (NTRS)

Marsik, S. J.; Swartz, C. K.; Baraona, C. R.

1978-01-01

Silicon solar cells and silicon wafers coated with a heat-curable resin consisting of alternating Si-O atoms were subjected to three tests to evaluate the potential utility of this coating in space environments. These included UV irradiation in vacuum at an intensity of 10 air mass zero UV energy-equivalent solar constants for 728 hours followed by a long thermal cycle; 15 thermal shock cycles between 100 C and minus 196 C; and high temperature and humidity (65 C at 90% relative humidity). The UV tests resulted in a 8 to 24% loss in short-circuit current and darkening of the covers. Modification of the resin to provide a better match between the coefficients of expansion of the resin and silicon improved resistance to thermal shock, but also increased the darkening effect under UV irradiation. Silicon wafers coated with the resin were not adversely affected by the temperature/humidity test.

ALL NATURAL COMPOSITE SANDWICH BEAMS FOR STRUCTURAL APPLICATIONS. (R829576)

EPA Science Inventory

As part of developing an all natural composite roof for housing application,
structural panels and unit beams were manufactured out of soybean oil based resin
and natural fibers (flax, cellulose, pulp, recycled paper, chicken feathers)
using vacuum assisted resin tran...

Vertical misfit of laser-sintered and vacuum-cast implant-supported crown copings luted with definitive and temporary luting agents.

PubMed

Castillo-de-Oyagüe, Raquel; Sánchez-Turrión, Andrés; López-Lozano, José-Francisco; Albaladejo, Alberto; Torres-Lagares, Daniel; Montero, Javier; Suárez-García, Maria-Jesús

2012-07-01

This study aimed to evaluate the vertical discrepancy of implant-supported crown structures constructed with vacuum-casting and Direct Metal Laser Sintering (DMLS) technologies, and luted with different cement types. Crown copings were fabricated using: (1) direct metal laser sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Ti (CT). Frameworks were luted onto machined implant abutments under constant seating pressure. Each alloy group was randomly divided into 5 subgroups (n = 10 each) according to the cement system utilized: Subgroup 1 (KC) used resin-modified glass-ionomer Ketac Cem Plus; Subgroup 2 (PF) used Panavia F 2.0 dual-cure resin cement; Subgroup 3 (RXU) used RelyX Unicem 2 Automix self-adhesive dual-cure resin cement; Subgroup 4 (PIC) used acrylic/urethane-based temporary Premier Implant Cement; and Subgroup 5 (DT) used acrylic/urethane-based temporary DentoTemp cement. Vertical misfit was measured by scanning electron microscopy (SEM). Two-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, and cement type on vertical misfit. The statistical significance was set at α = 0.05. The alloy/manufacturing technique and the luting cement affected the vertical discrepancy (p < 0.001). For each cement type, LS samples exhibited the best fit (p < 0.01) whereas CC and CT frames were statistically similar. Within each alloy group, PF and RXU provided comparably greater discrepancies than KC, PIC, and DT, which showed no differences. Laser sintering may be an alternative to vacuum-casting of base metals to obtain passive-fitting implant-supported crown copings. The best marginal adaptation corresponded to laser sintered structures luted with glass-ionomer KC, or temporary PIC or DT cements. The highest discrepancies were recorded for Co-Cr and Ti cast frameworks bonded with PF or RXU resinous agents. All groups were within the clinically acceptable misfit range.

Assisted Writing in Spin Transfer Torque Magnetic Tunnel Junctions

NASA Astrophysics Data System (ADS)

Ganguly, Samiran; Ahmed, Zeeshan; Datta, Supriyo; Marinero, Ernesto E.

2015-03-01

Spin transfer torque driven MRAM devices are now in an advanced state of development, and the importance of reducing the current requirement for writing information is well recognized. Different approaches to assist the writing process have been proposed such as spin orbit torque, spin Hall effect, voltage controlled magnetic anisotropy and thermal excitation. In this work,we report on our comparative study using the Spin-Circuit Approach regarding the total energy, the switching speed and energy-delay products for different assisted writing approaches in STT-MTJ devices using PMA magnets.

Technical assistance and the transfer of remote sensing technology. [for economic development

NASA Technical Reports Server (NTRS)

Chipman, R.

1977-01-01

The transfer of technology from industrialized countries to the third world is a very complicated process and one that requires a great deal of research and development. The political and social obstacles to this transfer are generally greater than the technical obstacles, but technical assistance programs have neither the competence nor the inclination to deal with these factors adequately. Funding for technical assistance in remote sensing is now expanding rapidly, and there is a growing need for institutions to study and promote the effective use of this technology for economic development. The United Nations, the Food and Agriculture Organization, the World Bank, the United States Agency for International Development and the Canadian technical assistance agencies take different approaches to the problem and deal with the political pressures in different ways.

Photoinduced charge transfer from vacuum-deposited molecules to single-layer transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Osada, Kazuki; Tanaka, Masatoshi; Ohno, Shinya; Suzuki, Takanori

2016-06-01

Variations of photoluminescence (PL) and Raman spectra of single-layer MoS2, MoSe2, WS2, and WSe2 due to the vacuum deposition of C60 or copper phthalocyanine (CuPc) molecules have been investigated. PL spectra are decomposed into two competitive components, an exciton and a charged exciton (trion), depending on carrier density. The variation of PL spectra is interpreted in terms of charge transfer across the interfaces between transition metal dichalcogenides (TMDs) and dopant molecules. We find that deposited C60 molecules inject photoexcited electrons into MoS2, MoSe2, and WS2 or holes into WSe2. CuPc molecules also inject electrons into MoS2, MoSe2, and WS2, while holes are depleted from WSe2 to CuPc. We then propose a band alignment between TMDs and dopant molecules. Peak shifts of Raman spectra and doped carrier density estimated using a three-level model also support the band alignment. We thus demonstrate photoinduced charge transfer from dopant molecules to single-layer TMDs.

Technical specification for vacuum systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khaw, J.

The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10/sup -5/ to 10/sup -11/ Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing andmore » designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components. (LEW)« less

Ultrasound -Assisted Gene Transfer to Adipose Tissue-Derived Stem/Progenitor Cells (ASCs)

NASA Astrophysics Data System (ADS)

Miyamoto, Yoshitaka; Ueno, Hitomi; Hokari, Rei; Yuan, Wenji; Kuno, Shuichi; Kakimoto, Takashi; Enosawa, Shin; Negishi, Yoichi; Yoshinaka, Kiyoshi; Matsumoto, Yoichiro; Chiba, Toshio; Hayashi, Shuji

2011-09-01

In recent years, multilineage adipose tissue-derived stem cells (ASCs) have become increasingly attractive as a promising source for cell transplantation and regenerative medicine. Particular interest has been expressed in the potential to make tissue stem cells, such as ASCs and marrow stromal cells (MSCs), differentiate by gene transfection. Gene transfection using highly efficient viral vectors such as adeno- and sendai viruses have been developed for this purpose. Sonoporation, or ultrasound (US)-assisted gene transfer, is an alternative gene manipulation technique which employs the creation of a jet stream by ultrasonic microbubble cavitation. Sonoporation using non-viral vectors is expected to be a much safer, although less efficient, tool for prospective clinical gene therapy. In this report, we assessed the efficacy of the sonoporation technique for gene transfer to ASCs. We isolated and cultured adipocyets from mouse adipose tissue. ASCs that have the potential to differentiate with transformation into adipocytes or osteoblasts were obtained. Using the US-assisted system, plasmid DNA containing beta-galactosidase (beta-Gal) and green fluorescent protein (GFP) genes were transferred to the ASCs. For this purpose, a Sonopore 4000 (NEPAGENE Co.) and a Sonazoid (Daiichi Sankyo Co.) instrument were used in combination. ASCs were subjected to US (3.1 MHz, 50% duty cycle, burst rate 2.0 Hz, intensity 1.2 W/cm2, exposure time 30 sec). We observed that the gene was more efficiently transferred with increased concentrations of plasmid DNA (5-150 μg/mL). However, further optimization of the US parameters is required, as the gene transfer efficiency was still relatively low. In conclusion, we herein demonstrate that a gene can be transferred to ASCs using our US-assisted system. In regenerative medicine, this system might resolve the current issues surrounding the use of viral vectors for gene transfer.

Liquid-Crystal Thermosets, a New Generation of High-Performance Liquid-Crystal Polymers

NASA Technical Reports Server (NTRS)

Dingemans, Theo; Weiser, Erik; Hou, Tan; Jensen, Brian; St. Clair, Terry

2004-01-01

One of the major challenges for NASA's next-generation reusable-launch-vehicle (RLV) program is the design of a cryogenic lightweight composite fuel tank. Potential matrix resin systems need to exhibit a low coefficient of thermal expansion (CTE), good mechanical strength, and excellent barrier properties at cryogenic temperatures under load. In addition, the resin system needs to be processable by a variety of non-autoclavable techniques, such as vacuum-bag curing, resin-transfer molding (RTM), vacuum-assisted resin-transfer molding (VaRTM), resin-film infusion (RFI), pultrusion, and advanced tow placement (ATP). To meet these requirements, the Advanced Materials and Processing Branch (AMPB) at NASA Langley Research Center developed a new family of wholly aromatic liquid-crystal oligomers that can be processed and thermally cross-linked while maintaining their liquid-crystal order. All the monomers were polymerized in the presence of a cross-linkable unit by use of an environmentally benign melt-condensation technique. This method does not require hazardous solvents, and the only side product is acetic acid. The final product can be obtained as a powder or granulate and has an infinite shelf life. The obtained oligomers melt into a nematic phase and do not exhibit isotropization temperatures greater than the temperatures of decomposition (Ti > T(sub dec)). Three aromatic formulations were designed and tested and included esters, ester-amides, and ester-imides. One of the major advantages of this invention, named LaRC-LCR or Langley Research Center-Liquid Crystal Resin, is the ability to control a variety of resin characteristics, such as melting temperature, viscosity, and the cross-link density of the final part. Depending on the formulation, oligomers can be prepared with melt viscosities in the range of 10-10,000 poise (100 rad/s), which can easily be melt-processed using a variety of composite-processing techniques. This capability provides NASA with custom

An innovative intermittent-vacuum assisted thermophilic anaerobic digestion process for effective animal manure utilization and treatment.

PubMed

Zhang, Renchuan; Anderson, Erik; Addy, Min; Deng, Xiangyuan; Kabir, Fayal; Lu, Qian; Ma, Yiwei; Cheng, Yanling; Liu, Yuhuan; Chen, Paul; Ruan, Roger

2017-11-01

Intermittent-vacuum stripping (IVS) was developed as a pretreatment for thermophilic anaerobic digestion (TAD) to improve methanogenesis and hydrolysis activity through preventing free ammonia and hydrogen sulfide (H 2 S) inhibition from liquid swine manure (LSM). Over 98% of ammonia and 38% organic nitrogen were removed in 60min from 55°C to 85°C with vacuum pressure (from 100.63±3.79mmHg to 360.91±7.39mmHg) at initial pH 10.0 by IVS. Thermophilic methanogenesis and hydrolysis activity of pretreated LSM increased 52.25% (from 11.56±1.75% to 17.60±0.49%) in 25days and 40% (from 10days to 6days) in bio-methane potential assay. Over 80% H 2 S and total nitrogen were removed by IVS assistance, while around 70% nitrogen was recycled as ammonium sulfate. Therefore, IVS-TAD combination could be an effective strategy to improve TAD efficiency, whose elution is more easily utilized in algae cultivation and/or hydroponic system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vacuum assisted birth and risk for cerebral complications in term newborn infants: a population-based cohort study.

PubMed

Ekéus, Cecilia; Högberg, Ulf; Norman, Mikael

2014-01-20

Few studies have focused on cerebral complications among newborn infants delivered by vacuum extraction (VE). The aim of this study was to determine the risk for intracranial haemorrhage and/or cerebral dysfunction in newborn infants delivered by VE and to compare this risk with that after cesarean section in labour (CS) and spontaneous vaginal delivery, respectively. Data was obtained from Swedish national registers. In a population-based cohort from 1999 to 2010 including all singleton newborn infants delivered at term after onset of labour by VE (n = 87,150), CS (75,216) or spontaneous vaginal delivery (n = 851,347), we compared the odds for neonatal intracranial haemorrhage, traumatic or non-traumatic, convulsions or encephalopathy. Logistic regressions were used to calculate adjusted (for major risk factors and indication) odds ratios (AOR), using spontaneous vaginal delivery as reference group. The rates of traumatic and non-traumatic intracranial hemorrhages were 0.8/10,000 and 3.8/1,000. VE deliveries provided 58% and 31.5% of the traumatic and non-traumatic cases, giving a ten-fold risk [AOR 10.05 (4.67-21.65)] and double risk [AOR 2.23 (1.57-3.16)], respectively. High birth weight and short mother were associated with the highest risks. Infants delivered by CS had no increased risk for intracranial hemorrhages. The risks for convulsions or encephalopathy were similar among infants delivered by VE and CS, exceeding the OR after non-assisted spontaneous vaginal delivery by two-to-three times. Vacuum assisted delivery is associated with increased risk for neonatal intracranial hemorrhages. Although causality could not be established in this observational study, it is important to be aware of the increased risk of intracranial hemorrhages in VE deliveries, particularly in short women and large infants. The results warrant further studies in decision making and conduct of assisted vaginal delivery.

Polyimides Based on Asymmetric Dianhydrides (II) (a-BPDA vs a-BTDA) for Resin Transfer Molding (RTM)

NASA Technical Reports Server (NTRS)

Chuang, Kathy C.; Criss, Jim M.; Mintz, Eric A.

2010-01-01

A new series of low-melt viscosity imide resins (10-20 poise at 280 C) were formulated from asymmetric 2,3,3',4' -benzophenone dianhydride (a-BTDA) and 4-phenylethynylphthalic endcaps, along with 3,4' -oxydianiline, 3,3' -methylenedianiline and 3,3'- diaminobenzophenone, using a solvent-free melt process. a-BTDA RTM resins exhibited higher glass transition temperatures (Tg's = 330-400 C) compared to those prepared by asymmetric 2,3,3',4' -biphenyl dianhydride, (a-BPDA, Tg's = 320-370 C). These low-melt viscosity imide resins were fabricated into polyimide/T650-35 carbon fiber composites by a RTM process. Composites properties of a-BTDA resins, such as open-hole compression and short-beam shear strength, are compared to those of composites made from a-BPDA based resin at room temperature, 288 C and 315 C. These novel, high temperature RTM imide resins exhibit outstanding properties beyond the performance of conventional RTM resins, such as epoxy and BMI resins which have use-temperatures around 177 C and 232 C for aerospace applications.

Emergency Food Assistance in Northern Syria: An Evaluation of Transfer Programs in Idleb Governorate.

PubMed

Doocy, Shannon; Tappis, Hannah; Lyles, Emily; Witiw, Joseph; Aken, Vicki

2017-06-01

The war in Syria has left millions struggling to survive amidst violent conflict, pervasive unemployment, and food insecurity. Although international assistance funding is also at an all-time high, it is insufficient to meet the needs of conflict-affected populations, and there is increasing pressure on humanitarian stakeholders to find more efficient, effective ways to provide assistance. To evaluate 3 different assistance programs (in-kind food commodities, food vouchers, and unrestricted vouchers) in Idleb Governorate of Syria from December 2014 and March 2015. The evaluation used repeated survey data from beneficiary households to determine whether assistance was successful in maintaining food security at the household level. Shopkeeper surveys and program monitoring data were used to assess the impact on markets at the district/governorate levels and compare the cost-efficiency and cost-effectiveness of transfer modalities. Both in-kind food assistance and voucher programs showed positive effects on household food security and economic measures in Idleb; however, no intervention was successful in improving all outcomes measured. Food transfers were more likely to improve food access and food security than vouchers and unrestricted vouchers. Voucher programs were found to be more cost-efficient than in-kind food assistance, and more cost-effective for increasing household food consumption. Continuation of multiple types of transfer programs, including both in-kind assistance and vouchers, will allow humanitarian actors to remain responsive to evolving access and security considerations, local needs, and market dynamics.

Preparation of novel polyamine-type chelating resin with hyperbranched structures and its adsorption performance

NASA Astrophysics Data System (ADS)

Chen, Youning; Zhao, Wei; Wang, Huan; Li, Yuhong; Li, Chenxi

2018-02-01

This paper explored the method of combining atom transfer radical polymerization (ATRP) technology and hyperbranched polymer principle to prepare the high capacity chelating resin. First, surface-initiated atom transfer radical polymerization (SI-ATRP) method was used to graft glycidyl methacrylate (GMA) on chloromethylated cross-linked styrene-divinylbenzene resin, and then the novel polyamine chelating resin with a kind of hyperbranched structure was prepared through the amination reaction between amino group of (2-aminoethyl) triamine and epoxy group in GMA. This resin had a selective effect on As(V) and Cr(VI) at a relatively low pH and can be used for the disposal of waste water containing As(V) and Cr(VI). It had a relatively strong adsorption effect on Cu(II), Pb(II), Cd(II) and Cr(III) and can be used for the disposal of heavy metal ion waste water. The finding was that, the adsorption capacity of resin on the studied heavy metal ions was higher than that of the chelating resin synthesized by traditional technology and also higher than that of the resin modified by ATRP technology and bifunctional chelator, indicating that the combination of ATRP and hyperbranched polymer concept is an effective method to prepare chelating resin with high capacity.

Preparation of novel polyamine-type chelating resin with hyperbranched structures and its adsorption performance

PubMed Central

Zhao, Wei; Wang, Huan; Li, Yuhong; Li, Chenxi

2018-01-01

This paper explored the method of combining atom transfer radical polymerization (ATRP) technology and hyperbranched polymer principle to prepare the high capacity chelating resin. First, surface-initiated atom transfer radical polymerization (SI-ATRP) method was used to graft glycidyl methacrylate (GMA) on chloromethylated cross-linked styrene-divinylbenzene resin, and then the novel polyamine chelating resin with a kind of hyperbranched structure was prepared through the amination reaction between amino group of (2-aminoethyl) triamine and epoxy group in GMA. This resin had a selective effect on As(V) and Cr(VI) at a relatively low pH and can be used for the disposal of waste water containing As(V) and Cr(VI). It had a relatively strong adsorption effect on Cu(II), Pb(II), Cd(II) and Cr(III) and can be used for the disposal of heavy metal ion waste water. The finding was that, the adsorption capacity of resin on the studied heavy metal ions was higher than that of the chelating resin synthesized by traditional technology and also higher than that of the resin modified by ATRP technology and bifunctional chelator, indicating that the combination of ATRP and hyperbranched polymer concept is an effective method to prepare chelating resin with high capacity. PMID:29515875

Comparison of intraocular pressure during the application of a liquid patient interface (FEMTO LDV Z8) for femtosecond laser-assisted cataract surgery using two different vacuum levels.

PubMed

Ebner, Martina; Mariacher, Siegfried; Januschowski, Kai; Boden, Katrin; Seuthe, Anna-Maria; Szurman, Peter; Boden, Karl Thomas

2017-08-01

To evaluate intraocular pressure (IOP) using the application of a novel liquid patient interface for femtosecond laser-assisted cataract surgery with the FEMTO LDV Z8. IOP was evaluated in enucleated porcine eyes prior, during and after the application of the Femto LDV Z8 liquid patient interface (Ziemer Ophthalmic Systems, Switzerland) using intracameral cannulation (n=20), intravitreal cannulation (n=20), rebound tonometry (n=20) and indentation tonometry (n=20). Pressure was assessed prior vacuum, during vacuum (30 s, 1 min, 2 min, 3 min) and after releasing the vacuum (1 min and 2 min). Two groups with different predefined vacuum levels (350 mbar, 420 mbar) were investigated. Mean intracameral pressure (±SD) increased during vacuum application from 20 mm Hg to 52.00 mm Hg (±6.35mm Hg; p=0.005) and 45.18 mmHg (±4.34 mm Hg; p=0.005) for the 420 mbar and the 350 mbar vacuum levels, respectively. Mean intravitreal pressure increased from 20 mm Hg to 25.60 mm Hg (±9.85 mm Hg; p=0.058) and 28.10 mm Hg (±2.54 mm Hg; p=0.059) for the 420 mbar and the 350 mbar vacuum levels, respectively. Pressure values from indentation and rebound tonometry were in between intracameral and intravitreal values. Mean intracameral IOP was 18.1% higher (p=0.019) in the 420 mbar group compared with the 350 mbar group. During vacuum application of the liquid patient interface of the Femto LDV Z8 for femtosecond laser-assisted cataract surgery, IOP values were higher in the anterior chamber compared with the intravitreal pressure measurements. The higher predefined vacuum level (350 mbar vs 420 mbar) resulted in significant higher intracameral IOP. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Processing and Characterization of Peti Composites Fabricated by High Temperature Vartm (Section)

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Cano, Roberto J.; Watson, Kent A.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Smith, Joseph G., Jr.; Loos, Alfred C.; Heider, Dirk

2011-01-01

The use of composites as primary structures on aerospace vehicles has increased dramatically over the past decade, but so have the production costs associated with their fabrication. For certain composites, high temperature vacuum assisted resin transfer molding (HT-VARTM) can offer reduced fabrication costs compared to conventional autoclave techniques. The process has been successfully used with phenylethynyl terminated imide (PETI) resins developed by NASA Langley Research Center (LaRC). In the current study, three PETI resins have been used to make test specimens using HT-VARTM. Based on previous work at NASA LaRC, larger panels with a quasi-isotropic lay-up were fabricated. The resultant composite specimens exhibited void contents of 3% by volume depending on the type of carbon fabric preform used. Mechanical properties of the panels were determined at both room and elevated temperatures. Fabric permeability characterizations and limited process modeling efforts were carried out to determine infusion times and composite panel size limitations. In addition, new PETI based resins were synthesized specifically for HT-VARTM.

Vacuum-insulated catalytic converter

DOEpatents

Benson, David K.

2001-01-01

A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

Sublimation-assisted graphene transfer technique based on small polyaromatic hydrocarbons

NASA Astrophysics Data System (ADS)

Chen, Mingguang; Stekovic, Dejan; Li, Wangxiang; Arkook, Bassim; Haddon, Robert C.; Bekyarova, Elena

2017-06-01

Advances in the chemical vapor deposition (CVD) growth of graphene have made this material a very attractive candidate for a number of applications including transparent conductors, electronics, optoeletronics, biomedical devices and energy storage. The CVD method requires transfer of graphene on a desired substrate and this is most commonly accomplished with polymers. The removal of polymer carriers is achieved with organic solvents or thermal treatment which makes this approach inappropriate for application to plastic thin films such as polyethylene terephthalate substrates. An ultraclean graphene transfer method under mild conditions is highly desired. In this article, we report a naphthalene-assisted graphene transfer technique which provides a reliable route to residue-free transfer of graphene to both hard and flexible substrates. The quality of the transferred graphene was characterized with atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. Field effect transistors, based on the naphthalene-transfered graphene, were fabricated and characterized. This work has the potential to broaden the applications of CVD graphene in fields where ultraclean graphene and mild graphene transfer conditions are required.

Three-body wear of resin denture teeth with and without nanofillers.

PubMed

Stober, Thomas; Henninger, Moritz; Schmitter, Marc; Pritsch, Maria; Rammelsberg, Peter

2010-02-01

The wear behavior of newly developed denture teeth with nanofillers may be different from teeth with other chemical formulations. The purpose of this study was to examine the 3-body wear resistance of 11 different commercially available resin denture teeth. The materials tested were conventional (SR Orthotyp PE, Orthognath) and cross-linked acrylic resin teeth without inorganic fillers (Premium 8, SR Postaris DCL, Trubyte Portrait, Artiplus), composite resin teeth with inorganic fillers (SR Orthosit PE, Vitapan), and composite resin teeth (experimental materials) with inorganic nanofillers (NC Veracia Posterior, e-Ha, Mondial). Human enamel and a ceramic denture tooth (Lumin Vacuum) were used as reference materials. The 3-body wear test was performed in a wear machine developed by the Academic Center for Dentistry Amsterdam (ACTA), with millet suspension acting as an abrasive medium (n=10, test load: 15 N, slip rate: 20%, number of cycles: 100,000). Wear was determined with the aid of a profilometer. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test using the closed testing approach (significance level for familywise error rate, alpha=.05). None of the acrylic and composite resin materials tested in this study demonstrated the 3-body wear resistance of ceramic teeth or human enamel. Teeth with inorganic fillers demonstrated significantly lower wear values than conventional or cross-linked acrylic resin teeth without fillers. Composite resin teeth with traditional fillers showed significantly lower wear than composite resin teeth with nanofillers. Denture teeth with and without inorganic fillers differed significantly with regard to the degree of wear generated in the ACTA wear simulator. The incorporation of nanofillers did not improve the wear resistance compared to teeth with traditional fillers.

Resin composite repair: Quantitative microleakage evaluation of resin-resin and resin-tooth interfaces with different surface treatments

PubMed Central

Celik, Cigdem; Cehreli, Sevi Burcak; Arhun, Neslihan

2015-01-01

Objective: The aim was to evaluate the effect of different adhesive systems and surface treatments on the integrity of resin-resin and resin-tooth interfaces after partial removal of preexisting resin composites using quantitative image analysis for microleakage testing protocol. Materials and Methods: A total of 80 human molar teeth were restored with either of the resin composites (Filtek Z250/GrandioSO) occlusally. The teeth were thermocycled (1000×). Mesial and distal 1/3 parts of the restorations were removed out leaving only middle part. One side of the cavity was finished with course diamond bur and the other was air-abraded with 50 μm Al2O3. They were randomly divided into four groups (n = 10) to receive: Group 1: Adper Single Bond 2; Group 2: All Bond 3; Group 3: ClearfilSE; Group 4: BeautiBond, before being repaired with the same resin composite (Filtek Z250). The specimens were re-thermocycled (1000×), sealed with nail varnish, stained with 0.5% basic fuchsin, sectioned mesiodistally and photographed digitally. The extent of dye penetration was measured by image analysis software (ImageJ) for both bur-finished and air-abraded surfaces at resin-tooth and resin-resin interfaces. The data were analyzed statistically. Results: BeautiBond exhibited the most microleakage at every site. Irrespective of adhesive and initial composite type, air-abrasion showed less microleakage except for BeautiBond. The type of initial repaired restorative material did not affect the microleakage. BeautiBond adhesive may not be preferred in resin composite repair in terms of microleakage prevention. Conclusions: Surface treatment with air-abrasion produced the lowest microleakage scores, independent of the adhesive systems and the pre-existing resin composite type. Pre-existing composite type does not affect the microleakage issue. All-in-one adhesive resin (BeautiBond) may not be preferred in resin composite repair in terms of microleakage prevention. PMID:25713491

Computer assisted thermal-vacuum testing

NASA Technical Reports Server (NTRS)

Petrie, W.; Mikk, G.

1977-01-01

In testing complex systems and components under dynamic thermal-vacuum environments, it is desirable to optimize the environment control sequence in order to reduce test duration and cost. This paper describes an approach where a computer is utilized as part of the test control operation. Real time test data is made available to the computer through time-sharing terminals at appropriate time intervals. A mathematical model of the test article and environmental control equipment is then operated on using the real time data to yield current thermal status, temperature analysis, trend prediction and recommended thermal control setting changes to arrive at the required thermal condition. The data acquisition interface and the time-sharing hook-up to an IBM-370 computer is described along with a typical control program and data demonstrating its use.

Boiling process modelling peculiarities analysis of the vacuum boiler

NASA Astrophysics Data System (ADS)

Slobodina, E. N.; Mikhailov, A. G.

2017-06-01

The analysis of the low and medium powered boiler equipment development was carried out, boiler units possible development directions with the purpose of energy efficiency improvement were identified. Engineering studies for the vacuum boilers applying are represented. Vacuum boiler heat-exchange processes where boiling water is the working body are considered. Heat-exchange intensification method under boiling at the maximum heat- transfer coefficient is examined. As a result of the conducted calculation studies, heat-transfer coefficients variation curves depending on the pressure, calculated through the analytical and numerical methodologies were obtained. The conclusion about the possibility of numerical computing method application through RPI ANSYS CFX for the boiling process description in boiler vacuum volume was given.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madhukar, M. S.; Martovetsky, N. N.

Large superconducting electromagnets used in fusion reactors utilize a large amount of glass/epoxy composite for electrical insulation and mechanical and thermal strengths. Moreover, the manufacture of these magnets involves wrapping each superconducting cable bundle with dry glass cloth followed by the vacuum-assisted resin transfer molding of the entire magnet. Due to their enormous size (more than 100 tons), it requires more than 40 h for resin impregnation and the subsequent pressure cycles to ensure complete impregnation and removal of any trapped air pockets. Diglycidyl ether of bisphenol F epoxy resin cross-linked with methyltetrahydrophthalic anhydride with an accelerator has been shownmore » to be a good candidate for use in composite parts requiring long impregnation cycles. Viscosity, gel time, and glass transition temperature of four resin-blends of diglycidyl ether of bisphenol F resin system were monitored as a function of time and temperature with an objective to find the blend that provides a working window longer than 40h at low viscosity without lowering its glass transition temperature. A resin-blend in the weight ratios of resin:hardener:accelerator=100:82:0.125 is shown to provide more than 60h at low resin viscosity while maintaining the same glass transition temperature as obtained with previously used resin-blends, based on the results.« less

Vertical misfit of laser-sintered and vacuum-cast implant-supported crown copings luted with definitive and temporary luting agents

PubMed Central

Sánchez-Turrión, Andrés; López-Lozano, José F.; Albaladejo, Alberto; Torres-Lagares, Daniel; Montero, Javier; Suárez-García, Maria J.

2012-01-01

Objectives. This study aimed to evaluate the vertical discrepancy of implant-supported crown structures constructed with vacuum-casting and Direct Metal Laser Sintering (DMLS) technologies, and luted with different cement types. Study Design. Crown copings were fabricated using: (1) direct metal laser sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Ti (CT). Frameworks were luted onto machined implant abutments under constant seating pressure. Each alloy group was randomly divided into 5 subgroups (n = 10 each) according to the cement system utilized: Subgroup 1 (KC) used resin-modified glass-ionomer Ketac Cem Plus; Subgroup 2 (PF) used Panavia F 2.0 dual-cure resin cement; Subgroup 3 (RXU) used RelyX Unicem 2 Automix self-adhesive dual-cure resin cement; Subgroup 4 (PIC) used acrylic/urethane-based temporary Premier Implant Cement; and Subgroup 5 (DT) used acrylic/urethane-based temporary DentoTemp cement. Vertical misfit was measured by scanning electron microscopy (SEM). Two-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, and cement type on vertical misfit. The statistical significance was set at α = 0.05. Results. The alloy/manufacturing technique and the luting cement affected the vertical discrepancy (p < 0.001). For each cement type, LS samples exhibited the best fit (p < 0.01) whereas CC and CT frames were statistically similar. Within each alloy group, PF and RXU provided comparably greater discrepancies than KC, PIC, and DT, which showed no differences. Conclusions. Laser sintering may be an alternative to vacuum-casting of base metals to obtain passive-fitting implant-supported crown copings. The best marginal adaptation corresponded to laser sintered structures luted with glass-ionomer KC, or temporary PIC or DT cements. The highest discrepancies were recorded for Co-Cr and Ti cast frameworks bonded with PF or RXU resinous agents. All groups were within the clinically

Potential mechanisms for bioregeneration of perchlorate-containing ion-exchange resin.

PubMed

Sharbatmaleki, Mohamadali; Unz, Richard F; Batista, Jacimaria R

2015-05-15

Ion-exchange (IX) is the most feasible technology for perchlorate removal from drinking water. Reuse of resins present challenges, however. Selective resins are non-regenerable, and are incinerated after one time use, while non-selective resins, when regenerable, produce a waste stream that contains high concentration of perchlorate that must be disposed of. A process to bioregenerate spent resin containing perchlorate with perchlorate-reducing bacteria (PRB) has been recently developed. In this research, potential mechanisms for bioregeneration of resin-attached perchlorate (RAP) were investigated. Batch bioregeneration experiments were performed using gel-type and macroporous-type resins. Various initial chloride concentrations and various resin bead sizes were used. The results of the bioregeneration experiments suggested that chloride, i.e. the product of perchlorate biodegradation, is more likely the desorbing agent of RAP; and increasing the concentration of chloride enhances the bioregeneration process. Both film and pore diffusion were found to be relevant with respect to the rate of perchlorate mass-transfer to the bulk liquid. Bioregeneration was found to be more effective for macroporous than for gel-type resins, especially in the case of macroporous resins with relatively small bead size in the presence of higher chloride concentration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Properties of radiation stable, low viscosity impregnating resin for cryogenic insulation system

NASA Astrophysics Data System (ADS)

Wu, Zhixiong; Zhang, Hao; Yang, Huihui; Chu, Xinxin; Song, Yuntao; Wu, Weiyue; Liu, Huajun; Li, Laifeng

2011-06-01

Impregnating resins in fusion magnet technology are required to be radiation stable, low viscosity, long usable life and high toughness. To meet these objectives, we developed a new epoxy based composite which consists of triglycidyl-p-aminophenol (TGPAP) epoxy resin and isopropylidenebisphenol bis[(2-glycidyloxy-3-n-butoxy)-1-propylether] (IPBE). The ratio of TGPAP to IPBE can be varied to achieve desired viscosity and working time. The boron-free glass fiber reinforced composites were prepared by vacuum pressure impregnation. The radiation resistance was evaluated by 60Co γ-ray irradiation of 1 MGy at ambient temperature. The mechanical properties of the composites have been measured at room temperature and at 77 K.

Further Development of a Robotic-Assisted Transfer Device

PubMed Central

Burkman, Jessica; Grindle, Garrett; Wang, Hongwu; Kelleher, Annmarie

2017-01-01

Background: The task of performing transfers, such as from a wheelchair to a bed, has a high risk of injury to both the caregiver and the person being transferred. Although mechanical transfer devices can reduce these risks, these devices are not meant for use in the community and they still place strain on the caregiver when used. Purpose: The aim of this study is to describe feedback gathered from focus groups of potential users of the Robotic-Assisted Transfer Device (RATD) and describe design changes aimed at preparing the device for the next step in the development process. Method: The RATD was transferred to a newer electric-powered wheelchair (EPW), key components were redesigned, and the control program was updated to increase the safety of the device. Two focus groups, one consisting of people with disabilities and the other consisting of clinicians and caregivers, were conducted to gather feedback from potential users. Results: Error checking, safety zones, a motor brake, and a new track helped increase the safety of the device. Sixty-three percent of the people with disabilities and 83% of caregivers surveyed said they would use the device. Conclusions: The results from the focus groups were positive and the design changes were successful, but more development is needed before the RATD can be marketed. PMID:29339890

Comparison of the adsorbed conformation of barley lipid transfer protein at the decane-water and vacuum-water interface: a molecular dynamics simulation.

PubMed

Euston, S R; Hughes, P; Naser, Md A; Westacott, R E

2008-05-01

Molecular dynamics simulation is used to model the adsorption of the barley lipid transfer protein (LTP) at the decane-water and vacuum-water interfaces. Adsorption at both surfaces is driven by displacement of water molecules from the interfacial region. LTP adsorbed at the decane surface exhibits significant changes in its tertiary structure, and penetrates a considerable distance into the decane phase. At the vacuum-water interface LTP shows small conformational changes away from its native structure and does not penetrate into the vacuum space. Modification of the conformational stability of LTP by reduction of its four disulphide bonds leads to an increase in conformational entropy of the molecules, which reduces the driving force for adsorption. Evidence for changes in the secondary structure are also observed for native LTP at the decane-water interface and reduced LTP at the vacuum-water interface. In particular, intermittent formation of short (six-residue) regions of beta-sheet is found in these two systems. Formation of interfacial beta-sheet in adsorbed proteins has been observed experimentally, notably in the globular milk protein beta-lactoglobulin and lysozyme.

Influence of different materials and techniques to transfer molding in multiple implants.

PubMed

Faria, Júlio C B; Cruz, Fernando L G; Silva-Concílio, Laís R; Neves, Ana C C

2012-01-01

The aim of this study was to compare different materials and techniques used in transfer molding of multiple implants, by evaluating the space between implants and superstructure. Four external hexagon implants were fixed in a master template and the same on a superstructure. Transfer molding of implants were done using the direct and indirect techniques, with transfers united or not, using the union chemically activated acrylic resin (QA) and other groups polymerized acrylic resin (FT), and sectioned and not split. The casts were made with polyether and models divided into 8 groups (n = 5). The space between the superstructure and the master implants was measured with a microscope and the data was analyzed statistically by Student's t test (p < 0.05). For the material of union there was no significant difference, except when the groups were compared with the resin Duralay QA (G4) and the resin Duolay FT (G8) and groups using resins Duolay QA (G5) and Duolay FT (G7) for the union of the transfers. When comparing the groups who had the union between the transfers and sectioned again united with those in which the union was not severed there was no statistically significant difference. QA resin was superior to the FT with respect to the union of transfers. Techniques with united transfers or not were similar.

Intrapartum translabial ultrasound with pushing used to predict the difficulty in vacuum-assisted delivery of fetuses in non-occiput posterior position.

PubMed

Antonio Sainz, José; Borrero, Carlota; Aquise, Adriana; García-Mejido, José Antonio; Gutierrez, Laura; Fernández-Palacín, Ana

2016-10-01

Our aim is to evaluate the capacity of intrapartum translabial ultrasound (ITU) with pushing in the prediction of difficulty of fetal extraction in vacuum assisted deliveries. Prospective, observational study performed (2/2015-8/2015) on 75 nulliparous women, ≥37 weeks with singleton pregnancies at full dilatation who had ITU-with-pushing performed, previous to vacuum-placement for fetal extraction. Working on the translabial sagittal-plane, we assessed: Angle-Progression (AoP), Progression-Distance (PD) and Head-Direction (HD); in the axial plane we evaluated: Midline-Angle (MLA) and Head-Perineum-Distance (HPD). Vacuum extractions were classified as easy-difficulty (ED) (≤3 vacuum-pulls), difficult-unsuccessful (DD) (>3 vacuum-pulls). We did not assess occipito-posterior-presentations. Seventy nulliparous were studied (44-ED,26-DD). We observed no differences in obstetric, neonatal or intrapartum characteristics between the two study groups, with the following exceptions: newborn weight (3272 ± 438 g versus 3540 ± 372 g; p = 0.011) and number of vacuum-pulls (1.4-ED-vs-4.4-DD; p < 0.0005). AoP-pushing was 143.9° ± 14.6° in ED and 115.1°± 12.9° in DD (p < 0.0005); Head-Up was 79.5% versus 38.4% (p < 0.0005); PD-Pushing was 42.7 ± 11.3 mm versus 30.4 ± 9.8 mm (p < 0.0005); MLA-Pushing was 27.6°± 26.6° versus 57.5°±26.5°(p=0.025); HPD-Pushing was 40.8 ± 10.0 mm versus 47.4 ± 10.9 mm (p = 0.039). We identified that the presence of an AoP-Pushing > 128° predicts an Easy-Vacuum-Delivery (≤3 Vacuum-Pulls) in  >85% of cases (Sen 80%-FPR 9.3%).

Electrostatic Assist of Liquid Transfer in Printing Processes

NASA Astrophysics Data System (ADS)

Huang, Chung-Hsuan; Kumar, Satish

2016-11-01

Transfer of liquid from one surface to another plays an important role in many printing processes. Incomplete liquid transfer can produce defects that are detrimental to the operation of printed electronic devices, and one strategy for minimizing these defects is to apply an electric field, a technique known as electrostatic assist (ESA). However, the underlying physical mechanisms of ESA remain a mystery. To better understand these mechanisms, slender-jet models for both perfect dielectric and leaky dielectric Newtonian liquid bridges with moving contact lines are developed. Nonlinear partial differential equations describing the time- and axial-evolution of the bridge radius and interfacial charge are derived, and then solved using finite-element methods. For perfect dielectrics, it is found that application of an electric field enhances transfer of liquid to the more wettable surface. For leaky dielectrics, application of an electric field can augment or oppose the influence of wettability differences, depending on the direction of the electric field and the sign of the interfacial charge. The physical mechanisms underlying these observations will be discussed.

Arthroscopic-assisted latissimus dorsi transfer for subscapularis deficiency.

PubMed

Kany, Jean; Guinand, Régis; Croutzet, Pierre; Valenti, Philippe; Werthel, Jean David; Grimberg, Jean

2016-04-01

Few salvage procedures have been described in case of irreparable subscapularis tear and with variable outcomes. Latissimus dorsi transfer has been widely proposed as a transfer for irreparable posterio-superior rotator cuff tear with good outcomes. The anatomic feasibility of the latissimus dorsi to reconstruct the antero-superior irreparable rotator cuff tear has been suggested, but no clinical study has ever been published. We hypothesized that it was possible to use an arthroscopic-assisted latissimus dorsi transfer to reconstruct the subscapularis function. Five patients were enrolled. A 5-7-cm axillary incision was performed to release the latissimus dorsi tendon from its humeral insertion, the teres major muscle and the apex of the scapula. Afterwards, under arthroscopic control, a 7-mm-diameter tunnel was drilled at the anterior and superior part of the humeral head with an oblique inferior and posterior direction. The tubularized latissimus dorsi tendon was introduced into the tunnel and fixed with a ZipLoop on the posterior humeral cortex. The authors show overall good experience with this technique. Level IV-a, case series.

[Caesarean section with vacuum extraction of the head].

PubMed

Dimitrov, A; Pavlova, E; Krŭsteva, K; Nikolov, A

2008-01-01

The aim of the study is to investigate the benefits and the limits in using the soft cup vacuum extractor on the fetal scalp during the caesarean section. The prospective study includes 19 cases of caesarean sections (group A), with vacuum assisted delivery using the soft cup vacuum extractor on the fetal scalp (diameter 6 cm) and 25 cases (group B) of caesarean sections with usual, manual extraction of the head assisted by fundal compression. All of the patients had undergone a planned caesarean section on term in absence of uterine activity and preserved amniotic membranes. Our results doesn't show differences in the Apgar score on the first and 5-th minute in the newborns of the two groups. The duration of the scalp traction was significantly shorter (30 +/- 4 sec) in comparison to the classical manual extraction (53 +/- 21 sec). The mean duration for applying the vacuum cup was 10 sec and 25 sec for tractions. The total blood loose and total duration of the caesarean sections were shorter than in the control group. The applied traction with the vacuum cup was sufficient for head extraction and there was no need for additional fundal compression. In conclusion we consider that the extraction of the fetal head in high position in caesarean section with vacuum extractor is an easy, non traumatic and rapid method which can put away the need of rough and prolonged fundal compression and its consequences.

Resin Film Infusion (RFI) Process Modeling for Large Transport Aircraft Wing Structures

NASA Technical Reports Server (NTRS)

Loos, Alfred C.; Caba, Aaron C.; Furrow, Keith W.

2000-01-01

This investigation completed the verification of a three-dimensional resin transfer molding/resin film infusion (RTM/RFI) process simulation model. The model incorporates resin flow through an anisotropic carbon fiber preform, cure kinetics of the resin, and heat transfer within the preform/tool assembly. The computer model can predict the flow front location, resin pressure distribution, and thermal profiles in the modeled part. The formulation for the flow model is given using the finite element/control volume (FE/CV) technique based on Darcy's Law of creeping flow through a porous media. The FE/CV technique is a numerically efficient method for finding the flow front location and the fluid pressure. The heat transfer model is based on the three-dimensional, transient heat conduction equation, including heat generation. Boundary conditions include specified temperature and convection. The code was designed with a modular approach so the flow and/or the thermal module may be turned on or off as desired. Both models are solved sequentially in a quasi-steady state fashion. A mesh refinement study was completed on a one-element thick model to determine the recommended size of elements that would result in a converged model for a typical RFI analysis. Guidelines are established for checking the convergence of a model, and the recommended element sizes are listed. Several experiments were conducted and computer simulations of the experiments were run to verify the simulation model. Isothermal, non-reacting flow in a T-stiffened section was simulated to verify the flow module. Predicted infiltration times were within 12-20% of measured times. The predicted pressures were approximately 50% of the measured pressures. A study was performed to attempt to explain the difference in pressures. Non-isothermal experiments with a reactive resin were modeled to verify the thermal module and the resin model. Two panels were manufactured using the RFI process. One was a stepped

Out of the Autoclave Fabrication of LaRC[TradeMark] PETI-9 Polyimide Laminates

NASA Technical Reports Server (NTRS)

Cano, Robert J.; Jensen, Brian J.

2013-01-01

The NASA Langley Research Center developed polyimide system, LaRC PETI-9, has successfully been processed into composites by high temperature vacuum assisted resin transfer molding (HT-VARTM). To extend the application of this high use temperature material to other out-of-autoclave (OOA) processing techniques, the fabrication of PETI- 9 laminates was evaluated using only a vacuum bag and oven cure. A LaRC PETI-9 polyimide solution in NMP was prepared and successfully utilized to fabricate unidirectional IM7 carbon fiber prepreg that was subsequently processed into composites with a vacuum bag and oven cure OOA process. Composite panels of good quality were successfully fabricated and mechanically tested. Processing characteristics, composite panel quality and mechanical properties are presented in this work. The resultant properties are compared to previously developed LaRC material systems processed by both autoclave and OOA techniques including the well characterized, autoclave processed LaRC PETI-5.

Occupational dermatoses from exposure to epoxy resin compounds in a ski factory.

PubMed

Jolanki, R; Tarvainen, K; Tatar, T; Estlander, T; Henriks-Eckerman, M L; Mustakallio, K K; Kanerva, L

1996-06-01

Of 22 workers in a ski factory, occupational allergic contact dermatitis was found in 8. 6 were sensitive to epoxy resin compounds, i.e., epoxy resins, hardeners or diluents, 1 to cobalt in glass-fiber reinforcements, and 1 to formaldehyde in a urea-formaldehyde glue and a lacquer. 4 workers had irritant contact dermatitis from epoxy resin compounds, lacquers, sanding dust, or glass-fiber dust. 3 had contact allergy from a new sensitizer, diethyleneglycol diglycidyl ether, in a reactive diluent. Immediate transfer of workers sensitized to epoxy resin from epoxy exposure prevents aggravation of their dermatitis and broadening of the sensitization to epoxy hardeners, diluents and other compounds.

Long-term clinical evaluation of a 800-nm long-pulsed diode laser with a large spot size and vacuum-assisted suction for hair removal.

PubMed

Ibrahimi, Omar A; Kilmer, Suzanne L

2012-06-01

The long-pulsed diode (800-810-nm) laser is one of the most commonly used and effective lasers for hair removal. Limitations of currently available devices include a small treatment spot size, treatment-associated pain, and the need for skin cooling. To evaluate the long-term hair reduction capabilities of a long-pulsed diode laser with a large spot size and vacuum assisted suction. Thirty-five subjects were enrolled in a prospective, self-controlled, single-center study of axillary hair removal. The study consisted of three treatments using a long-pulsed diode laser with a large spot size and vacuum-assisted suction at 4- to 6-week intervals with follow-up visits 6 and 15 months after the last treatment. Hair clearance was quantified using macro hair-count photographs taken at baseline and at 6- and 15-month follow-up visits. Changes in hair thickness and color, levels of treatment-associated pain, and adverse events were additional study endpoints. There was statistically significant hair clearance at the 6 (54%) and 15-month (42%) follow-up visits. Remaining hairs were thinner and lighter at the 15-month follow-up visit, and the majority of subjects reported feeling up to mild to moderate pain during treatment without the use of pretreatment anesthesia or skin cooling. A long-pulsed diode laser with a large spot size and vacuum-assisted suction is safe and effective for long-term hair removal. This is the largest prospective study to evaluate long-term hair removal and the first to quantify decreases in hair thickness and darkness with treatment. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

Fabrication of nanowire electronics on nonconventional substrates by water-assisted transfer printing method

NASA Astrophysics Data System (ADS)

Lee, Chi Hwan; Kim, Dong Rip; Zheng, Xiaolin

2015-06-01

We report a simple, versatile, and wafer-scale water-assisted transfer printing method (WTP) that enables the transfer of nanowire devices onto diverse nonconventional substrates that were not easily accessible before, such as paper, plastics, tapes, glass, polydimethylsiloxane (PDMS), aluminum foil, and ultrathin polymer substrates. The WTP method relies on the phenomenon of water penetrating into the interface between Ni and SiO2. The transfer yield is nearly 100%, and the transferred devices, including NW resistors, diodes, and field effect transistors, maintain their original geometries and electronic properties with high fidelity.

Embedded fiber optic sensors for monitoring processing, quality and structural health of resin transfer molded components

NASA Astrophysics Data System (ADS)

Keulen, C.; Rocha, B.; Yildiz, M.; Suleman, A.

2011-07-01

Due to their small size and flexibility fiber optics can be embedded into composite materials with little negative effect on strength and reliability of the host material. Fiber optic sensors such as Fiber Bragg Gratings (FBG) or Etched Fiber Sensors (EFS) can be used to detect a number of relevant parameters such as flow, degree of cure, quality and structural health throughout the life of a composite component. With a detection algorithm these embedded sensors can be used to detect damage in real time while the component remains in service. This paper presents the research being conducted on the use of fiber optic sensors for process and Structural Health Monitoring (SHM) of Resin Transfer Molded (RTM) composite structures. Fiber optic sensors are used at all life stages of an RTM composite panel. A laboratory scale RTM apparatus was developed with the capability of visually monitoring the resin filling process. A technique for embedding fiber optic sensors with this apparatus has also been developed. Both FBGs and EFSs have been embedded in composite panels using the apparatus. EFSs to monitor the fabrication process, specifically resin flow have been embedded and shown to be capable of detecting the presence of resin at various locations as it is injected into the mold. Simultaneously these sensors were multiplexed on the same fiber with FBGs, which have the ability to measure strain. Since multiple sensors can be multiplexed on a single fiber the number of ingress/egress locations required per sensor can be significantly reduced. To characterize the FBGs for strain detection tensile test specimens with embedded FBG sensors have been produced. These specimens have been instrumented with a resistive strain gauge for benchmarking. Both specimens and embedded sensors were characterized through tensile testing. Furthermore FBGs have been embedded into composite panels in a manner that is conducive to detection of Lamb waves generated with a centrally located PZT

Polyimide Resins Resist Extreme Temperatures

NASA Technical Reports Server (NTRS)

2009-01-01

Spacecraft and aerospace engines share a common threat: high temperature. The temperatures experienced during atmospheric reentry can reach over 2,000 F, and the temperatures in rocket engines can reach well over 5,000 F. To combat the high temperatures in aerospace applications, Dr. Ruth Pater of Langley Research Center developed RP-46, a polyimide resin capable of withstanding the most brutal temperatures. The composite material can push the service temperature to the limits of organic materials. Designed as an environmentally friendly alternative to other high-temperature resins, the RP-46 polyimide resin system was awarded a 1992 "R&D 100" award, named a "2001 NASA Technology of the Year," and later, due to its success as a spinoff technology, "2004 NASA Commercial Invention of the Year." The technology s commercial success also led to its winning the Langley s "Paul F. Holloway Technology Transfer Award" as well as "Richard T. Whitcom Aerospace Technology Transfer Award" both for 2004. RP-46 is relatively inexpensive and it can be readily processed for use as an adhesive, composite, resin molding, coating, foam, or film. Its composite materials can be used in temperatures ranging from minus 150 F to 2,300 F. No other organic materials are known to be capable of such wide range and extreme high-temperature applications. In addition to answering the call for environmentally conscious high-temperature materials, RP-46 provides a slew of additional advantages: It is extremely lightweight (less than half the weight of aluminum), chemical and moisture resistant, strong, and flexible. Pater also developed a similar technology, RP-50, using many of the same methods she used with RP-46, and very similar in composition to RP-46 in terms of its thermal capacity and chemical construction, but it has different applications, as this material is a coating as opposed to a buildable composite. A NASA license for use of this material outside of the Space Agency as well as

A vacuum flash-assisted solution process for high-efficiency large-area perovskite solar cells

NASA Astrophysics Data System (ADS)

Li, Xiong; Bi, Dongqin; Yi, Chenyi; Décoppet, Jean-David; Luo, Jingshan; Zakeeruddin, Shaik Mohammed; Hagfeldt, Anders; Grätzel, Michael

2016-07-01

Metal halide perovskite solar cells (PSCs) currently attract enormous research interest because of their high solar-to-electric power conversion efficiency (PCE) and low fabrication costs, but their practical development is hampered by difficulties in achieving high performance with large-size devices. We devised a simple vacuum flash-assisted solution processing method to obtain shiny, smooth, crystalline perovskite films of high electronic quality over large areas. This enabled us to fabricate solar cells with an aperture area exceeding 1 square centimeter, a maximum efficiency of 20.5%, and a certified PCE of 19.6%. By contrast, the best certified PCE to date is 15.6% for PSCs of similar size. We demonstrate that the reproducibility of the method is excellent and that the cells show virtually no hysteresis. Our approach enables the realization of highly efficient large-area PSCs for practical deployment.

The residual monomer content and mechanical properties of CAD\\CAM resins used in the fabrication of complete dentures as compared to heat cured resins

PubMed Central

Ayman, Al-Dharrab

2017-01-01

Background The utilization of computer-assisted designing and computer-assisted milling CAD\\CAM resins in the fabrication of removable prostheses is a modern-day concept that offers many advantages over the use of the traditional polymethylmethacrylate (PMMA). Aim This study instigated some of the mechanical properties of CAD\\CAM denture base resin including the amount of residual monomer. Methods This study was conducted at the Faculty of Dentistry, King Abdulaziz University from October 2016 to February 2017. A total of seventy rectangular specimens were fabricated (group A: 35 heat-cured PMMA and group B: 35 CAD/CAM pre-polymerized acrylic resin blocks). The flexural strength and surface hardness were tested while the residual monomer content at baseline, two-day and seven-day intervals was estimated using gas chromatography (GC). Means and standard deviations were determined for each group as well as independent-samples t-test and ANOVA with repeated measures for comparison between the groups and subgroups of varying time intervals. Results Heat cured PMMA (A), displayed higher flexural strength and low value flexural modulus compared to CAD/CAM acrylic resin denture base material (B). Student t-test indicated highly significant differences (p<0.001) of the flexural strength (t=37.911) and flexural modulus (t=88.559). The surface hardness of group (B) was significantly higher compared to group (A) as indicated by the t-test (t=20.430). Higher release of the monomer content was detected by GC in group (A) at different time intervals with a statistically significant difference (p<0.001) in residual monomer content. Conclusion CAD/CAM resin may be considered suitable for use in the construction of denture bases. PMID:28894533

High risk of fistula formation in vacuum-assisted closure therapy in patients with open abdomen due to secondary peritonitis-a retrospective analysis.

PubMed

Mintziras, Ioannis; Miligkos, Michael; Bartsch, Detlef Klaus

2016-08-01

The aim of this study was to evaluate the efficacy of vacuum-assisted closure therapy in patients with open abdomen due to secondary peritonitis and to identify possible risk factors of fistula formation. The hospital OPS-database (time period 2005-2014) was searched to identify patients treated with an open abdomen due to secondary peritonitis, who underwent vacuum-assisted closure therapy. Medical records were retrospectively analyzed for patients' characteristics, cause of peritonitis, duration of vacuum therapy, number of relaparotomies, fascial closure rates, and risk factors of fistula formation. Forty-three patients (19 male, 24 female) with a median age of 65 years (range 24-90 years) were identified. The major cause of secondary peritonitis was anastomotic leakage after intestinal anastomosis or bowel perforation, the median APACHE II score was 11. Median duration of VAC treatment was 12 days (range 3-88 days). Twenty of 43 (47 %) patients died from septic complications. Delayed fascial closure was obtained by suturing in 20 of 43 patients (47 %). Overall 16 of 43 (37 %) patients developed enteroatmospheric fistulas. Re-explorations after starting VAC treatment and duration of VAC therapy were significantly associated with the occurrence of enteroatmospheric fistulas (p < 0.001). ROC curve analysis determined the optimal duration of VAC therapy to reduce the risk of fistula formation at 13 days. Long-term VAC treatment of patients with an open abdomen due to secondary peritonitis results in a relatively low fascial closure rate and a high risk of fistula formation.

Outgassing of solid material into vacuum thermal insulation spaces

NASA Technical Reports Server (NTRS)

Wang, Pao-Lien

1994-01-01

Many cryogenic storage tanks use vacuum between inner and outer tank for thermal insulation. These cryogenic tanks also use a radiation shield barrier in the vacuum space to prevent radiation heat transfer. This shield is usually constructed by using multiple wraps of aluminized mylar and glass paper as inserts. For obtaining maximum thermal performance, a good vacuum level must be maintained with the insulation system. It has been found that over a period of time solid insulation materials will vaporize into the vacuum space and the vacuum will degrade. In order to determine the degradation of vacuum, the rate of outgassing of the insulation materials must be determined. Outgassing rate of several insulation materials obtained from literature search were listed in tabular form.

Manufacturing process modeling for composite materials and structures, Sandia blade reliability collaborative

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guest, Daniel A.; Cairns, Douglas S.

2014-02-01

The increased use and interest in wind energy over the last few years has necessitated an increase in the manufacturing of wind turbine blades. This increase in manufacturing has in many ways out stepped the current understanding of not only the materials used but also the manufacturing methods used to construct composite laminates. The goal of this study is to develop a list of process parameters which influence the quality of composite laminates manufactured using vacuum assisted resin transfer molding and to evaluate how they influence laminate quality. Known to be primary factors for the manufacturing process are resin flowmore » rate and vacuum pressure. An incorrect balance of these parameters will often cause porosity or voids in laminates that ultimately degrade the strength of the composite. Fiber waviness has also been seen as a major contributor to failures in wind turbine blades and is often the effect of mishandling during the lay-up process. Based on laboratory tests conducted, a relationship between these parameters and laminate quality has been established which will be a valuable tool in developing best practices and standard procedures for the manufacture of wind turbine blade composites.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fetfatsidis, K. A.; Sherwood, J. A.

NCFs (Non-Crimp Fabrics) are commonly used in the design of wind turbine blades and other complex systems due to their ability to conform to complex shapes without the wrinkling that is typically experienced with woven fabrics or prepreg tapes. In the current research, a form of vacuum assisted resin transfer molding known as SCRIMP registered is used to manufacture wind turbine blades. Often, during the compacting of the fabric layers by the vacuum pressure, several plies may bunch together out-of-plane and form wave defects. When the resin is infused, the areas beneath the waves become resin rich and can compromisemore » the structural integrity of the blade. A reliable simulation tool is valuable to help predict where waves and other defects may appear as a result of the manufacturing process. Forming simulations often focus on the in-plane shearing and tensile behavior of fabrics and do not necessarily consider the bending stiffness of the fabrics, which is important to predict the formation of wrinkles and/or waves. This study incorporates experimentally determined in-plane shearing, tensile, and bending stiffness information of NCFs into a finite element model (ABAQUS/Explicit) of a 9-meter wind turbine blade to investigate the mechanical behaviors that can lead to the formation of waves as a result of the manufacturing process.« less

Reinforced carbon fiber laminates with oriented carbon nanotube epoxy nanocomposites: Magnetic field assisted alignment and cryogenic temperature mechanical properties.

PubMed

He, Yuxin; Yang, Song; Liu, Hu; Shao, Qian; Chen, Qiuyu; Lu, Chang; Jiang, Yuanli; Liu, Chuntai; Guo, Zhanhu

2018-05-01

The epoxy nanocomposites with ordered multi-walled carbon nanotubes (MWCNTs) were used to influence the micro-cracks resistance of carbon fiber reinforced epoxy (CF/EP) laminate at 77 K, Oxidized MWCNTs functionalized with Fe 3 O 4 (Fe 3 O 4 /O-MWCNTs) with good magnetic properties were prepared by co-precipitation method and used to modify epoxy (EP) for cryogenic applications. Fe 3 O 4 /O-MWCNTs reinforced carbon fiber epoxy composites were also prepared through vacuum-assisted resin transfer molding (VARTM). The ordered Fe 3 O 4 /O-MWCNTs were observed to have effectively improved the mechanical properties of epoxy (EP) matrix at 77 K and reduce the coefficient of thermal expansion (CTE) of EP matrix. The ordered Fe 3 O 4 /O-MWCNTs also obviously improved the micro-cracks resistance of CF/EP composites at 77 K. Compared to neat EP, the CTE of ordered Fe 3 O 4 /O-MWCNTs modified CF/EP composites was decreased 37.6%. Compared to CF/EP composites, the micro-cracks density of ordered Fe 3 O 4 /O-MWCNTs modified CF/EP composites at 77 K was decreased 37.2%. Copyright © 2018 Elsevier Inc. All rights reserved.

Clinical impact of the disposable ventouse iCup® versus a metallic vacuum cup: a multicenter randomized controlled trial.

PubMed

Equy, Véronique; David-Tchouda, Sandra; Dreyfus, Michel; Riethmuller, Didier; Vendittelli, Françoise; Cabaud, Victoire; Langer, Bruno; Margier, Jennifer; Bosson, Jean-Luc; Schaal, Jean-Patrick

2015-12-15

Assisted vaginal delivery by vacuum extraction is frequent. Metallic resterilizible metallic vacuum cups have been routinely used in France. In the last few years a new disposable semi-soft vacuum extraction cup, the iCup, has been introduced. Our objective was to compare maternal and new-born outcomes between this disposable cup and the commonly used Drapier-Faure metallic cup. This was a multicenter prospective randomized controlled open clinical trial performed in the maternity units of five university hospitals and one community hospital in France from October 2009 to February 2013. We included consecutive eligible women with a singleton gestation of at least 37 weeks who required vacuum assisted delivery. Women were randomized to vacuum extraction using the iCup or usual Drapier-Faure metallic cup. The primary outcome was a composite criterion including both the risk of cup dysfunction and the most frequent maternal and neonatal harms: the use of other instruments after attempted vacuum extraction, caesarean section after attempted vacuum extraction, three detachments of the cup, caput succedaneum, cephalohaematoma, episiotomy and perineal tears. 335 women were randomized to the disposable cup and 333 to extraction using the metallic cup. There was no significant difference between the two groups for the primary outcome. However, failed instrumental delivery was more frequent in the disposable cup group, mainly due to detachment: 35.6 % vs 7.1 %, p < 0.0001. Conversely, perineal tears were more frequent in the metallic cup group, especially third or fourth grade perineal tears: 1.7 % versus 5.0 %, p = 0.003. There were no significant differences between the two groups concerning post-partum haemorrhage, transfer to a neonatal intensive care unit (NICU) or serious adverse events. While the disposable cup had more detachments and extraction failures than the standard metallic cup, this innovative disposable device had the advantage of fewer perineal

Solvent Free Low-Melt Viscosity Imide Oligomers And Thermosetting Polyimide Composites

NASA Technical Reports Server (NTRS)

Chuang, CHun-Hua (Inventor)

2006-01-01

This invention relates to the composition and a solvent-free process for preparing novel imide oligomers and polymers specifically formulated with effective amounts of a dianhydride such as 2,3,3',4-biphenyltetra carboxylic dianydride (a-BPDA), at least one aromatic diamine' and an endcapped of 4-phenylethynylphthalic anhydride (PEPA) or nadic anhydride to produce imide oligomers that possess a low-melt viscosity of 1-60 poise at 260-280" C. When the imide oligomer melt is cured at about 371 C. in a press or autoclave under 100-500 psi, the melt resulted in a thermoset polyimide having a glass transition temperature (T(sub g)) equal to and above 310 C. A novel feature of this process is that the monomers; namely the dianhydrides, diamines and the endcaps, are melt processable to form imide oligomers at temperatures ranging between 232-280 C. (450-535 F) without any solvent. These low-melt imide oligomers can be easily processed by resin transfer molding (RTM), vacuum-assisted resin transfer molding (VARTM) or the resin infusion process with fiber preforms e.g. carbon, glass or quartz preforms to produce polyimide matrix composites with 288-343C (550-650 F) high temperature performance capability.

Optimization of the transfer trajectory of a low-thrust spacecraft for research of Jupiter using an Earth gravity-assist maneuver

NASA Astrophysics Data System (ADS)

Konstantinov, M. S.; Orlov, A. A.

2014-12-01

The paper analyzes the possibility of the use of a gravity-assist maneuver for flight to Jupiter. The advantage of the Earth gravity-assist maneuver in comparison with the direct transfer in terms of reduction of amount of energy required per transfer is considered. Quantitative and qualitative evaluations of two transfer profiles are given.

Post-Planck constraints on interacting vacuum energy

NASA Astrophysics Data System (ADS)

Wang, Yuting; Wands, David; Zhao, Gong-Bo; Xu, Lixin

2014-07-01

We present improved constraints on an interacting vacuum model using updated astronomical observations including the first data release from Planck. We consider a model with one dimensionless parameter, α, describing the interaction between dark matter and vacuum energy (with fixed equation of state w=-1). The background dynamics correspond to a generalized Chaplygin gas cosmology, but the perturbations have a zero sound speed. The tension between the value of the Hubble constant, H0, determined by Planck data plus WMAP polarization (Planck +WP) and that determined by the Hubble Space Telescope (HST) can be alleviated by energy transfer from dark matter to vacuum (α>0). A positive α increases the allowed values of H0 due to parameter degeneracy within the model using only cosmic microwave background data. Combining with additional data sets of including supernova type Ia (SN Ia) and baryon acoustic oscillation (BAO), we can significantly tighten the bounds on α. Redshift-space distortions (RSD), which constrain the linear growth of structure, provide the tightest constraints on vacuum interaction when combined with Planck+WP, and prefer energy transfer from vacuum to dark matter (α<0) which suppresses the growth of structure. Using the combined data sets of Planck +WP+Union2.1+BAO+RSD, we obtain the constraint on α to be -0.083<α<-0.006 (95% C.L.), allowing low H0 consistent with the measurement from 6dF Galaxy survey. This interacting vacuum model can alleviate the tension between RSD and Planck +WP in the ΛCDM model for α <0, or between HST measurements of H0 and Planck+WP for α>0, but not both at the same time.

Application of a Fiber Optic Distributed Strain Sensor System to Woven E-Glass Composite

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Lopatin, Craig

2001-01-01

A distributed strain sensing system utilizing a series of identically written Bragg gratings along an optical fiber is examined for potential application to Composite Armored Vehicle health monitoring. A vacuum assisted resin transfer molding process was used to fabricate a woven fabric E-glass/composite panel with an embedded fiber optic strain sensor. Test samples machined from the panel were mechanically tested in 4-point bending. Experimental results are presented that show the mechanical strain from foil strain gages comparing well to optical strain from the embedded sensors. Also, it was found that the distributed strain along the sample length was consistent with the loading configuration.

The influence of EI-21 redox ion-exchange resins on the secondary-coolant circuit water chemistry of vehicular nuclear power installations

NASA Astrophysics Data System (ADS)

Moskvin, L. N.; Rakov, V. T.

2015-06-01

The results obtained from testing the secondary-coolant circuit water chemistry of full-scale land-based prototype bench models of vehicular nuclear power installations equipped with water-cooled water-moderated and liquid-metal reactor plants are presented. The influence of copper-containing redox ionexchange resins intended for chemically deoxygenating steam condensate on the working fluid circulation loop's water chemistry is determined. The influence of redox ion-exchange resins on the water chemistry is evaluated by generalizing an array of data obtained in the course of extended monitoring using the methods relating to physicochemical analysis of the quality of condensate-feedwater path media and the methods relating to metallographic analysis of the state of a faulty steam generator's tube system surfaces. The deoxygenating effectiveness of the normal state turbine condensate vacuum deaeration system is experimentally determined. The refusal from applying redox ion-exchange resins in the condensate polishing ion-exchange filters is formulated based on the obtained data on the adverse effect of copper-containing redox ionexchange resins on the condensate-feedwater path water chemistry and based on the data testifying a sufficient effect from using the normal state turbine condensate vacuum deaeration system. Data on long-term operation of the prototype bench model of a vehicular nuclear power installation without subjecting the turbine condensate to chemical deoxygenation are presented.

Novel Low-Melt Viscosity Polyimides for Resin Transfer Molding (RTM)

DTIC Science & Technology

2008-08-29

used no solvent in the process and the only volatile generated is water tbrmed during the imidization process. Resins were prepared as outlined below...without the use of a solvent. Due to the commercial availabilit \\ of 3,4’ -ODA, RTM370 is cheaper to manufacture than RTM 350 or RTM330. All these rcsins

Molecular dynamics simulation of the cooperative adsorption of barley lipid transfer protein and cis-isocohumulone at the vacuum-water interface.

PubMed

Euston, S R; Hughes, P; Naser, Md A; Westacott, R E

2008-11-01

Molecular dynamic simulations have been carried out on systems containing a mixture of barley lipid transfer protein (LTP) and cis-isocohumulone (a hop derived iso-alpha-acid) in one of its enol forms, in bulk water and at the vacuum-water interface. In solution, the cis-isocohumulone molecules bind to the surface of the LTP molecule. The mechanism of binding appears to be purely hydrophobic in nature via desolvation of the protein surface. Binding of hop acids to the LTP leads to a small change in the 3-D conformation of the protein, but no change in the proportion of secondary structure present in helices, even though there is a significant degree of hop acid binding to the helical regions. At the vacuum-water interface, cis-isocohumulone shows a high surface activity and adsorbs rapidly at the interface. LTP then shows a preference to bind to the preadsorbed hop acid layer at the interface rather than to the bare water-vacuum interface. The free energy of adsorption of LTP at the hop-vacuum-water interface is more favorable than for adsorption at the vacuum-water interface. Our results support the view that hop iso-alpha-acids promote beer foam stability by forming bridges between separate adsorbed protein molecules, thus strengthening the adsorbed protein layer and reducing foam breakdown by lamellar phase drainage. The results also suggest a second mechanism may also occur, whereby the concentration of protein at the interface is increased via enhanced protein adsorption to adsorbed hop acid layers. This too would increase foam stability through its effect on the stabilizing protein layer around the foam bubbles.

Preparation of waterborne dispersions of epoxy resin by ultrasonic-assisted supercritical CO2 nanoemulsification technique.

PubMed

Gao, Hanyang; Hu, Guoxin; Liu, Kun; Wu, Liqun

2017-11-01

Waterborne nanoemulsion of diglycidyl ether of bisphenol A type epoxy resin (DGEBA) with droplet size of around 124nm was prepared by using an ultrasonic-assisted supercritical carbon dioxide (scCO 2 ) technique in an autoclave reactor at a low temperature (32°C). A view cell positioned in-line with the ultrasonic probe allowed observation of the emulsification process. From the image analysis and droplet size measurement, the influence mechanisms of the ultrasonic power, the degree of mixing of scCO 2 with DGEBA, the adding amount of emulsifier, and the system pressure on emulsification process and emulsion droplet size were investigated. In the emulsification process, scCO 2 penetrated into the mixture and absorbed on the DGEBA molecular. The interactions between CO 2 and the functional groups of DGEBA reduced the chain-chain interactions of polymer segments and therefore efficiently reduced the viscosity of DGEBA at a low temperature. Meantime, the cavitation and acoustic streaming of ultrasound provided a shear force for the nanoemulsification and a disturbance force for the homogeneity of the emulsion. Therefore, the combination of scCO 2 and ultrasonication made it possible to prepare a long-term stable nanoemulsion under a low temperature. This ultrasonic-assisted scCO 2 emulsification method provides an efficient and solvent-free process for the preparation of waterborne nanoemulsions of, for example, some heat-sensitive and water-insoluble active substances at low temperature. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of potential hazards associated with 241Am loaded resins from nitrate media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schulte, Louis D.; Rubin, Jim; Fife, Keith William

2016-02-19

LANL has been contacted to provide possible assistance in safe disposition of a number of 241Am-bearing materials associated with local industrial operations. Among the materials are ion exchange resins which have been in contact with 241Am and nitric acid, and which might have potential for exothermic reaction. The purpose of this paper is to analyze and define the resin forms and quantities to the extent possible from available data to allow better bounding of the potential reactivity hazard of the resin materials. An additional purpose is to recommend handling procedures to minimize the probability of an uncontrolled exothermic reaction.

Static and Dynamic Mechanical Properties of Graphene Oxide-Incorporated Woven Carbon Fiber/Epoxy Composite

NASA Astrophysics Data System (ADS)

Adak, Nitai Chandra; Chhetri, Suman; Kim, Nam Hoon; Murmu, Naresh Chandra; Samanta, Pranab; Kuila, Tapas

2018-03-01

This study investigates the synergistic effects of graphene oxide (GO) on the woven carbon fiber (CF)-reinforced epoxy composites. The GO nanofiller was incorporated into the epoxy resin with variations in the content, and the CF/epoxy composites were manufactured using a vacuum-assisted resin transfer molding process and then cured at 70 and 120 °C. An analysis of the mechanical properties of the GO (0.2 wt.%)/CF/epoxy composites showed an improvement in the tensile strength, Young's modulus, toughness, flexural strength and flexural modulus by 34, 20, 83, 55 and 31%, respectively, when compared to the CF/epoxy composite. The dynamic mechanical analysis of the composites exhibited an enhancement of 56, 114 and 22% in the storage modulus, loss modulus and damping capacity (tan δ), respectively, at its glass transition temperature. The fiber-matrix interaction was studied using a Cole-Cole plot analysis.

THE DURABILITY OF LARGE-SCALE ADDITIVE MANUFACTURING COMPOSITE MOLDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, Brian K; Love, Lonnie J; Duty, Chad

2016-01-01

Oak Ridge National Laboratory s Big Area Additive Manufacturing (BAAM) technology permits the rapid production of thermoplastic composite molds using a carbon fiber filled Acrylonitrile-Butadiene-Styrene (ABS) thermoplastic. Demonstration tools (i.e. 0.965 m X 0.559 m X 0.152 m) for composite part fabrication have been printed, coated, and finished with a traditional tooling gel. We present validation results demonstrating the stability of thermoplastic printed molds for room temperature Vacuum Assisted Resin Transfer Molding (VARTM) processes. Arkema s Elium thermoplastic resin was investigated with a variety of reinforcement materials. Experimental results include dimensional characterization of the tool surface using laser scanning techniquemore » following demolding of 10 parts. Thermoplastic composite molds offer rapid production compared to traditionally built thermoset molds in that near-net deposition allows direct digital production of the net geometry at production rate of 45 kg/hr.« less

Sunlight assisted direct amide formation via a charge-transfer complex.

PubMed

Cohen, Irit; Mishra, Abhaya K; Parvari, Galit; Edrei, Rachel; Dantus, Mauricio; Eichen, Yoav; Szpilman, Alex M

2017-09-12

We report on the use of charge-transfer complexes between amines and carbon tetrachloride, as a novel way to activate the amine for photochemical reactions. This principle is demonstrated in a mild, transition metal free, visible light assisted, dealkylative amide formation from feedstock carboxylic acids and amines. The low absorption coefficient of the complex allows deep light penetration and thus scale up to a gram scale.

Gage measures total radiation, including vacuum UV, from ionized high-temperature gases

NASA Technical Reports Server (NTRS)

Wood, A. D.

1969-01-01

Transient-heat transfer gage measures the total radiation intensity from vacuum ultraviolet and ionized high temperature gases. The gage includes a sensitive piezoelectric crystal that is completely isolated from any ionized flow and vacuum ultraviolet irradiation.

Microwave-assisted extraction performed in low temperature and in vacuo for the extraction of labile compounds in food samples.

PubMed

Xiao, Xiaohua; Song, Wei; Wang, Jiayue; Li, Gongke

2012-01-27

In this study, low temperature vacuum microwave-assisted extraction, which simultaneous performed microwave-assisted extraction (MAE) in low temperature and in vacuo environment, was proposed. The influencing parameters including solid/liquid ratio, extraction temperature, extraction time, degree of vacuum and microwave power were discussed. The predominance of low temperature vacuum microwave-assisted extraction was investigated by comparing the extraction yields of vitamin C, β-carotene, aloin A and astaxanthin in different foods with that in MAE and solvent extraction, and 5.2-243% increments were obtained. On the other hand, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. All of the decomposition rates (K(2)) for the selected analyte in low temperature, in vacuo and in nitrogen atmosphere decreased significantly comparing with that in conventional MAE, which are in agreement with that obtained from experiments. Consequently, the present method was successfully applied to extract labile compound from different food samples. These results showed that low temperature and/or in vacuo environment in microwave-assisted extraction system was especially important to prevent the degradation of labile components and have good potential on the extraction of labile compound in foods, pharmaceutical and natural products. Copyright © 2011 Elsevier B.V. All rights reserved.

Vertical discrepancy and microleakage of laser-sintered and vacuum-cast implant-supported structures luted with different cement types.

PubMed

Oyagüe, Raquel Castillo; Sánchez-Turrión, Andrés; López-Lozano, José Francisco; Suárez-García, M Jesús

2012-02-01

This study aimed to evaluate the vertical misfit and microleakage of laser-sintered and vacuum-cast cement-retained implant-supported frameworks. Three-unit implant-fixed structures were constructed with: (1) laser-sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Pd-Au (CP). Every framework was luted onto 2 prefabricated abutments under constant seating pressure. Each alloy group was randomly divided into three subgroups (n=10) according to the cement used: (1) Ketac Cem Plus (KC); (2) Panavia F 2.0 (PF); and (3) RelyX Unicem 2 Automix (RXU). After 30 days of water ageing, vertical discrepancy was measured by SEM, and marginal microleakage was scored using a digital microscope. Three-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, FDP retainer, and cement type on vertical misfit. Data for marginal microleakage were analysed with Kruskal-Wallis and Dunn's tests (α=0.05). Vertical discrepancy was affected by alloy/manufacturing technique and cement type (p<0.001). Despite the luting agent, LS structures showed the best marginal adaptation, followed by CP, and CC. Within each alloy group, KC provided the best fit, whilst the use of PF or RXU resulted in no significant differences. Regardless of the framework alloy, KC exhibited the highest microleakage scores, whilst PF and RXU showed values that were comparable to each other. Laser-sintered Co-Cr structures achieved the best fit in the study. Notwithstanding the framework alloy, resin-modified glass-ionomer demonstrated better marginal fit but greater microleakage than did MDP-based and self-adhesive dual-cure resin cements. All groups were within the clinically acceptable misfit range. Laser-sintered Co-Cr may be an alternative to cast base metal and noble alloys to obtain passive-fitting structures. Despite showing higher discrepancies, resin cements displayed lower microleakage than resin-modified glass-ionomer. Further research is

Internal motion in high vacuum systems

NASA Astrophysics Data System (ADS)

Frank, J. M.

Three transfer and positioning mechanisms have been developed for the non-air exposed, multistep processing of components in vacuum chambers. The functions to be performed in all of the systems include ultraviolet/ozone cleaning, vacuum baking, deposition of thin films, and thermocompression sealing of the enclosures. Precise positioning of the components is required during the evaporation and sealing processes. The three methods of transporting and positioning the components were developed to accommodate the design criteria and goals of each individual system. The design philosophy, goals, and operation of the three mechanisms are discussed.

Development and characterization of soy-based epoxy resins and pultruded FRP composites

NASA Astrophysics Data System (ADS)

Zhu, Jiang

This dissertation focuses on the development, manufacture and characterization of novel soy-based epoxy FRP composites. Use of alternative epoxy resin systems derived from a renewable resource holds potential for low cost raw materials for the polymer and composite industries. Epoxidized Allyl Soyate (EAS) and Epoxidized Methyl Soyate (EMS) were developed from soybean oil with two chemical modification procedures: transesterification and epoxidation. This research investigates the curing characteristics and thermal and mechanical properties of the neat soyate resin systems. The derived soyate resins have higher reactivity and superior performance compared to commercially available epoxidized soybean oil. An efficient two-step curing method was developed in order to utilize these soyate resins to their full potential. The epoxy co-resin systems with varied soyate resin content were successfully used to fabricate composite material through pultrusion. The pultrusion resin systems with 30 wt% soyate resins yielded improved, or comparable mechanical properties with neat commercial resins. A finite element analysis of the heat transfer and curing process was performed to study the processing characterization on glass/epoxy composite pultrusion. This model can be used to establish baseline process variables and will benefit subsequent optimization. This research demonstrates that soy-based resins, especially EAS, show considerable promise as an epoxy resin supplement for use in polymer and composite structural applications. The new products derived from soybean oil can provide competitive performance, low cost and environmental advantages.

High Temperature VARTM with LaRC Polyimides

NASA Technical Reports Server (NTRS)

Cano, Roberto J.; Grimsley, Brian W.; Jensen, Brian J.; Kellen, Charles B.

2004-01-01

Recent work at NASA Langley Research Center (LaRC) has concentrated on developing new polyimide resin systems for advanced aerospace applications that can be processed without the use of an autoclave. Polyimide composites are very attractive for applications that require a high strength to weight ratio and thermal stability. Vacuum assisted resin transfer molding (VARTM) has shown potential to reduce the manufacturing cost of composite structures. In VARTM, the fibrous preform is infiltrated on a rigid tool surface contained beneath a flexible vacuum bag. Both resin injection and fiber compaction are achieved under pressures of 101.3 KPa or less. Recent studies have demonstrated the feasibility of the VARTM process for fabrication of void free structures utilizing epoxy resin systems with fiber volume fractions approaching 60%. In this work, the VARTM process has been extended to the fabrication of composite panels from polyimide systems developed at the Langley Research Center. This work has focused on processing LARC(trademark) PETI-8 (Langley Research Center Phenylethynyl Terminated Imide- 8), an aromatic polyimide based on 3,3',4,4' -biphenyltetracarboxylic dianhydride, a 50:50 molar ratio of 3,4'-oxydianiline and 1,3-bis(3-aminophenoxy)benzene, with 4-phenylethynylphthalic anhydride as the endcapping agent. Various molecular weight versions were investigated to determine their feasibility of being processed by VARTM at elevated temperatures. An injection temperature of approximately 280 C was required to achieve the necessary viscosity (<5 Poise) for flow at VARTM pressures. Laminate quality and initial mechanical properties are presented for LARC(trademark) PETI-8 and 6k IM7 uniweave fabric.

Method and apparatus for performing in-situ vacuum-assisted metal to glass sealing

DOEpatents

Kramer, D.P.; Massey, R.T.

1985-07-18

A method and apparatus for assembling and fusing glass to metal in a glass-metal electrical component is disclosed. The component includes a metallic shell formed with upper and lower cylindrical recesses connected together by longitudinal passages, a pair of metal rings and plural metal pins assembled to define electrical feed-throughs. The component parts are assembled on a fixture having a sleeve-like projection and a central mounting projection establishing concentric nesting surfaces to which the metal rings are slip-fitted in concentric alignment with each other spaced from sidewalls of the lower recess. The pins are in electrical contact with the metal rings. A glass pre-form is seated within the upper recess. The assembled structure is heated to a temperature sufficient to melt the glass pre-form which flows under gravity through the passages into the lower recess to provide an insulative seal between the metal parts. The gravity flow of glass is assisted by applying vacuum to the lower recess, ensuring that all spaces between the metal parts are filled with sealing glass without formation of bubbles.

Method and apparatus for performing in-situ vacuum-assisted metal to glass sealing

DOEpatents

Kramer, Daniel P.; Massey, Richard T.

1986-01-01

A method and apparatus for assembling and fusing glass to metal in a glass-metal electrical component is disclosed. The component includes a metallic shell formed with upper and lower cylindrical recesses connected together by longitudinal passages, a pair of metal rings and plural metal pins assembled to define electrical feed-throughs. The component parts are assembled on a fixture having a sleeve-like projection and a central mounting projection establishing concentric nesting surfaces to which the metal rings are slip-fitted in concentric alignment with each other spaced from sidewalls of the lower recess. The pins are in electrical contact with the metal rings. A glass pre-form is seated within the upper recess. The assembled structure is heated to a temperature sufficient to melt the glass pre-form which flows under gravity through the passages into the lower recess to provide an insulative seal between the metal parts. The gravity flow of glass is assisted by applying vacuum to the lower recess, ensuring that all spaces between the metal parts are filled with sealing glass without formation of bubbles.

Properties of Two Carbon Composite Materials Using LTM25 Epoxy Resin

NASA Technical Reports Server (NTRS)

Cruz, Juan R.; Shah, C. H.; Postyn, A. S.

1996-01-01

In this report, the properties of two carbon-epoxy prepreg materials are presented. The epoxy resin used in these two materials can yield lower manufacturing costs due to its low initial cure temperature, and the capability of being cured using vacuum pressure only. The two materials selected for this study are MR50/LTM25, and CFS003/LTM25 with Amoco T300 fiber; both prepregs are manufactured by The Advanced Composites Group. MR50/LTM25 is a unidirectional prepreg tape using Mitsubishi MR50 carbon fiber impregnated with LTM25 epoxy resin. CRS003/LTM25 is a 2 by 2 twill fabric using Amoco T300 fiber and impregnated with LTM25 epoxy resin. Among the properties presented in this report are strength, stiffness, bolt bearing, and damage tolerance. Many of these properties were obtained at three environmental conditions: cold temperature/dry (CTD), room temperature/dry (RTD), and elevated temperature/wet (ETW). A few properties were obtained at room temperature/wet (RTW), and elevated temperature/dry (ETD). The cold and elevated temperatures used for testing were -125 F and 180 F, respectively. In addition, several properties related to processing are presented.

Laser-assisted simultaneous transfer and patterning of vertically aligned carbon nanotube arrays on polymer substrates for flexible devices.

PubMed

In, Jung Bin; Lee, Daeho; Fornasiero, Francesco; Noy, Aleksandr; Grigoropoulos, Costas P

2012-09-25

We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications.

Development of Textile Reinforced Composites for Aircraft Structures

NASA Technical Reports Server (NTRS)

Dexter, H. Benson

1998-01-01

NASA has been a leader in development of composite materials for aircraft applications during the past 25 years. In the early 1980's NASA and others conducted research to improve damage tolerance of composite structures through the use of toughened resins but these resins were not cost-effective. The aircraft industry wanted affordable, robust structures that could withstand the rigors of flight service with minimal damage. The cost and damage tolerance barriers of conventional laminated composites led NASA to focus on new concepts in composites which would incorporate the automated manufacturing methods of the textiles industry and which would incorporate through-the-thickness reinforcements. The NASA Advanced Composites Technology (ACT) Program provided the resources to extensively investigate the application of textile processes to next generation aircraft wing and fuselage structures. This paper discusses advanced textile material forms that have been developed, innovative machine concepts and key technology advancements required for future application of textile reinforced composites in commercial transport aircraft. Multiaxial warp knitting, triaxial braiding and through-the-thickness stitching are the three textile processes that have surfaced as the most promising for further development. Textile reinforced composite structural elements that have been developed in the NASA ACT Program are discussed. Included are braided fuselage frames and window-belt reinforcements, woven/stitched lower fuselage side panels, stitched multiaxial warp knit wing skins, and braided wing stiffeners. In addition, low-cost processing concepts such as resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM) are discussed. Process modeling concepts to predict resin flow and cure in textile preforms are also discussed.

Low lift-to-drag aero-assisted orbit transfer vehicles

NASA Technical Reports Server (NTRS)

Andrews, D. G.; Savage, R. T.

1984-01-01

The results of systems analysis conducted on low life drag ratio (L/D) aero-assisted orbit transfer vehicle (AOTV's) are presented. The objectives for this class of vehicle and formulate technology development plans and funding levels to bring the required technologies to readiness levels, as well as develop a credible decision data base encompassing the entire range of low L/D concepts for use in future NASA Aeroassist Orbit Transfer Vehicles studies. Each candidate low L/D concept, the aerobrake, the lifting brake, and the aeromaneuvering concept could be made to work with technologies achievable by the early 1990's. All concepts require flexible structure with flexible thermal protection system (TPS) to be successfully integrated into the shuttle orbiter for launch, all required improvements in guidance and control to fly the dispersed atmospheres at high altitude, and all concepts had potential to evolve from ground-based to space-based operations.

Compressed Air/Vacuum Transportation Techniques

NASA Astrophysics Data System (ADS)

Guha, Shyamal

2011-03-01

General theory of compressed air/vacuum transportation will be presented. In this transportation, a vehicle (such as an automobile or a rail car) is powered either by compressed air or by air at near vacuum pressure. Four version of such transportation is feasible. In all versions, a ``c-shaped'' plastic or ceramic pipe lies buried a few inches under the ground surface. This pipe carries compressed air or air at near vacuum pressure. In type I transportation, a vehicle draws compressed air (or vacuum) from this buried pipe. Using turbine or reciprocating air cylinder, mechanical power is generated from compressed air (or from vacuum). This mechanical power transferred to the wheels of an automobile (or a rail car) drives the vehicle. In type II-IV transportation techniques, a horizontal force is generated inside the plastic (or ceramic) pipe. A set of vertical and horizontal steel bars is used to transmit this force to the automobile on the road (or to a rail car on rail track). The proposed transportation system has following merits: virtually accident free; highly energy efficient; pollution free and it will not contribute to carbon dioxide emission. Some developmental work on this transportation will be needed before it can be used by the traveling public. The entire transportation system could be computer controlled.

Gas propagation in a liquid helium cooled vacuum tube following a sudden vacuum loss

NASA Astrophysics Data System (ADS)

Dhuley, Ram C.

This dissertation describes the propagation of near atmospheric nitrogen gas that rushes into a liquid helium cooled vacuum tube after the tube suddenly loses vacuum. The loss-of-vacuum scenario resembles accidental venting of atmospheric air to the beam-line of a superconducting radio frequency particle accelerator and is investigated to understand how in the presence of condensation, the in-flowing air will propagate in such geometry. In a series of controlled experiments, room temperature nitrogen gas (a substitute for air) at a variety of mass flow rates was vented to a high vacuum tube immersed in a bath of liquid helium. Pressure probes and thermometers installed on the tube along its length measured respectively the tube pressure and tube wall temperature rise due to gas flooding and condensation. At high mass in-flow rates a gas front propagated down the vacuum tube but with a continuously decreasing speed. Regression analysis of the measured front arrival times indicates that the speed decreases nearly exponentially with the travel length. At low enough mass in-flow rates, no front propagated in the vacuum tube. Instead, the in-flowing gas steadily condensed over a short section of the tube near its entrance and the front appeared to `freeze-out'. An analytical expression is derived for gas front propagation speed in a vacuum tube in the presence of condensation. The analytical model qualitatively explains the front deceleration and flow freeze-out. The model is then simplified and supplemented with condensation heat/mass transfer data to again find the front to decelerate exponentially while going away from the tube entrance. Within the experimental and procedural uncertainty, the exponential decay length-scales obtained from the front arrival time regression and from the simplified model agree.

Differences in interfacial bond strengths of graphite fiber-epoxy resin composites

NASA Technical Reports Server (NTRS)

Needles, H. L.

1985-01-01

The effect of epoxy-size and degree of cure on the interfacial bonding of an epoxy-amine-graphite fiber composite system is examined. The role of the fiber-resin interface in determining the overall mechanical properties of composites is poorly understood. A good interfacial adhesive bond is required to achieve maximum stress transfer to the fibers in composites, but at the same time some form of energy absorbing interfacial interaction is needed to achieve high fracture toughening. The incompatibility of these two processes makes it important to understand the nature and basic factors involved at the fiber-resin interface as stress is applied. The mechanical properties including interlaminar shear values for graphite fiber-resin composites are low compared to glass and boron-resin composites. These differences have been attributed to poor fiber-matrix adhesion. Graphite fibers are commonly subjected to post-treatments including application of organic sizing in order to improve their compatibility with the resin matrix and to protect the fiber tow from damage during processing and lay-up. In such processes, sized graphite fiber tow is impregnated with epoxy resin and then layed-up i nto the appropriate configuration. Following an extended ambient temperature cure, the graphite-resin composite structure is cured at elevated temperature using a programmed temperature sequence to cure and then cool the product.

NASA's southeast technology transfer alliance: A cooperative technology assistance initiative

NASA Astrophysics Data System (ADS)

Craft, Harry G.; Sheehan, William; Johnson, Anne

1996-03-01

Since 1958, NASA has been charged with actively assisting in the transfer of technologies derived from the United States space program into the industrial sector of the U.S. economy. This has historically been accomplished through technology transfer offices working independently at each NASA field center. NASA recently restructured the program to provide regional coordination, maximize efficiencies, eliminate redundancies, and capitalize on each center's fundamental technology strengths. The nation is divided into six NASA technology transfer geographical regions with each region containing one or more NASA field centers and a regional technology transfer center. The southeast region includes the states of Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee. The NASA field centers in this region are: the Marshall Space Flight Center in Huntsville, Alabama; the Kennedy Space Center in Florida; and the Stennis Space Center in Bay St. Louis, Mississippi. The centers have teamed to focus primarily on regional industries and businesses, to provide a wide range of resources for U.S. industries, including access to unique government facilities, regional workshops, and technical problem solving. Hundreds of American businesses have benefited from this new regional initiative, as evidenced by reports of over 10,500 added or saved jobs and over 988 million worth of economic impacts as a result of their technology transfer activities.

Absorbing film assisted laser induced forward transfer of fungi (Trichoderma conidia)

NASA Astrophysics Data System (ADS)

Hopp, B.; Smausz, T.; Antal, Zs.; Kresz, N.; Bor, Zs.; Chrisey, D.

2004-09-01

We present an investigation on absorbing film assisted laser induced forward transfer (AFA-LIFT) of fungus (Trichoderma) conidia. A KrF excimer laser beam [λ =248nm,FWHM=30ns (FWHM, full width at half maximum)] was directed through a quartz plate and focused onto its silver coated surface where conidia of the Trichoderma strain were uniformly spread. The laser fluence was varied in the range of 0-2600mJ/cm2 and each laser pulse transferred a pixel of target material. The average irradiated area was 8×10-2mm2. After the transfer procedure, the yeast extract medium covered glass slide and the transferred conidia patterns were incubated for 20 h and then observed using an optical microscope. The transferred conidia pixels were germinated and the areas of the culture medium surfaces covered by the pixels were evaluated as a function of laser fluence. As the laser fluence was increased from 0 to 355mJ/cm2 the transferred and germinated pixel area increased from 0 to 0.25mm2. Further increase in fluence resulted in a drastic decrease down to an approximately constant value of 0.06mm2. The yield of successful transfer by AFA-LIFT and germination was as much as 75% at 355mJ/cm2. The results prove that AFA-LIFT can successfully be applied for the controlled transfer of biological objects.

Ejector/liquid ring pump provides <0. 30 mm Hg vacuum for polymerization vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lockwood, A.; Gaines, A.

1982-03-01

Firestone Fibers and Textiles Company, a division of Firestone Tire and Rubber Company, manufactures tire and industrial yarns of polyester and nylon-6. Nylon-6 molding and extrusion resins are also produced at the plant in Hopewell, Virginia. The process for making polyester requires an extremely low vacuum on the polymerization reactor. A consistent polymerization vessel vacuum of 0.3 mm Hg is needed, but the existing vacuum source, a five-stage steam jet ejector, could only provide a 0.5 mm Hg level. Two options were considered when the company decided to replace the original system with a system designed for 0.15 mm Hgmore » with a non-condensible gas load of 10.8 lb/hr. A new five-stage jet ejector system to meet these requirements would use 1395 lb/hr of 100 psig steam. The other option was a hybrid vacuum source composed of a three-stage steam ejector system and a liquid ring vacuum pump that is more energy efficient than ejectors for low vacuum applications. The hybrid system was selected because the three-stage jet ejector would use only 1240 lb/hr of 100 psig steam. The liquid ring vacuum pump would increase the material and installation cost of the system by about $4000, but the savings in steam consumption would pay back the added cost in less than two years. The jet ejector/liquid ring vacuum pump system has provided both the capacity and the extremely low vacuum needed for the polyester polymerization vessel, after making a small modification. The hybrid vacuum source is reliable, requires only routine maintenance, and will contiue to save substantial amounts of steam each year compared to the five-stage steam jet ejector.« less

Fluorinion transfer in silver-assisted chemical etching for silicon nanowires arrays

NASA Astrophysics Data System (ADS)

Feng, Tianyu; Xu, Youlong; Zhang, Zhengwei; Mao, Shengchun

2015-08-01

Uniform silicon nanowires arrays (SiNWAs) were fabricated on unpolished rough silicon wafers through KOH pretreatment followed by silver-assisted chemical etching (SACE). Density functional theory (DFT) calculations were used to investigate the function of silver (Ag) at atomic scale in the etching process. Among three adsorption sites of Ag atom on Si(1 0 0) surface, Ag(T4) above the fourth-layer surface Si atoms could transfer fluorinion (F-) to adjacent Si successfully due to its stronger electrostatic attraction force between Ag(T4) and F-, smaller azimuth angle of Fsbnd Ag(T4)sbnd Si, shorter bond length of Fsbnd Si compared with Fsbnd Ag. As F- was transferred to adjacent Si by Ag(T4) one by one, the Si got away from the wafer in the form of SiF4 when it bonded with enough F- while Ag(T4) was still attached onto the Si wafer ready for next transfer. Cyclic voltammetry tests confirmed that Ag can improve the etching rate by transferring F- to Si.

Overall Quality of Fruits and Vegetables Products Affected by the Drying Processes with the Assistance of Vacuum-Microwaves.

PubMed

Figiel, Adam; Michalska, Anna

2016-12-30

The seasonality of fruits and vegetables makes it impossible to consume and use them throughout the year, thus numerous processing efforts have been made to offer an alternative to their fresh consumption and application. To prolong their availability on the market, drying has received special attention as currently this method is considered one of the most common ways for obtaining food and pharmaceutical products from natural sources. This paper demonstrates the weakness of common drying methods applied for fruits and vegetables and the possible ways to improve the quality using different drying techniques or their combination with an emphasis on the microwave energy. Particular attention has been drawn to the combined drying with the assistance of vacuum-microwaves. The quality of the dried products was ascribed by chemical properties including the content of polyphenols, antioxidant capacity and volatiles as well as physical parameters such as color, shrinkage, porosity and texture. Both these fields of quality classification were considered taking into account sensory attributes and energy aspects in the perspective of possible industrial applications. In conclusion, the most promising way for improving the quality of dried fruit and vegetable products is hybrid drying consisting of osmotic dehydration in concentrated fruit juices followed by heat pump drying and vacuum-microwave finish drying.

Overall Quality of Fruits and Vegetables Products Affected by the Drying Processes with the Assistance of Vacuum-Microwaves

PubMed Central

Figiel, Adam; Michalska, Anna

2016-01-01

The seasonality of fruits and vegetables makes it impossible to consume and use them throughout the year, thus numerous processing efforts have been made to offer an alternative to their fresh consumption and application. To prolong their availability on the market, drying has received special attention as currently this method is considered one of the most common ways for obtaining food and pharmaceutical products from natural sources. This paper demonstrates the weakness of common drying methods applied for fruits and vegetables and the possible ways to improve the quality using different drying techniques or their combination with an emphasis on the microwave energy. Particular attention has been drawn to the combined drying with the assistance of vacuum-microwaves. The quality of the dried products was ascribed by chemical properties including the content of polyphenols, antioxidant capacity and volatiles as well as physical parameters such as color, shrinkage, porosity and texture. Both these fields of quality classification were considered taking into account sensory attributes and energy aspects in the perspective of possible industrial applications. In conclusion, the most promising way for improving the quality of dried fruit and vegetable products is hybrid drying consisting of osmotic dehydration in concentrated fruit juices followed by heat pump drying and vacuum-microwave finish drying. PMID:28042845

Imprint cytology on microcalcifications excised by vacuum-assisted breast biopsy: a rapid preliminary diagnosis.

PubMed

Fotou, Maria; Oikonomou, Vassiliki; Zagouri, Flora; Sergentanis, Theodoros N; Nonni, Afroditi; Athanassiadou, Pauline; Drouveli, Theodora; Atsouris, Efstratios; Kotzia, Evagelia; Zografos, George C

2007-04-03

To evaluate imprint cytology in the context of specimens with microcalcifications derived from Vacuum-Assisted Breast Biopsy (VABB). A total of 93 women with microcalcifications BI-RADS 3 and 4 underwent VABB and imprint samples were examined. VABB was performed on Fischer's table using 11-gauge Mammotome vacuum probes. A mammogram of the cores after the procedure confirmed the excision of microcalcifications. For the application of imprint cytology, the cores with microcalcifications confirmed by mammogram were gently rolled against glass microscope slides and thus imprint smears were made. For rapid preliminary diagnosis Diff-Quick stain, modified Papanicolaou stain and May Grunwald Giemsa were used. Afterwards, the core was dipped into a CytoRich Red Collection fluid for a few seconds in order to obtain samples with the use of the specimen wash. After the completion of cytological procedures, the core was prepared for routine histological study. The pathologist was blind to the preliminary cytological results. The cytological and pathological diagnoses were comparatively evaluated. According to the pathological examination, 73 lesions were benign, 15 lesions were carcinomas (12 ductal carcinomas in situ, 3 invasive ductal carcinomas), and 5 lesions were precursor: 3 cases of atypical ductal hyperplasia (ADH) and 2 cases of lobular neoplasia (LN). The observed sensitivity and specificity of the cytological imprints for cancer were 100% (one-sided, 97.5% CI: 78.2%-100%). Only one case of ADH could be detected by imprint cytology. Neither of the two LN cases was detected by the imprints. The imprints were uninformative in 11 out of 93 cases (11.8%). There was no uninformative case among women with malignancy. Imprint cytology provides a rapid, accurate preliminary diagnosis in a few minutes. This method might contribute to the diagnosis of early breast cancer and possibly attenuates patients' anxiety.

Resin Viscosity Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

NASA Astrophysics Data System (ADS)

Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

2018-06-01

Viscosity of the liquid resin effects the chemical and mechanical properties of the pultruded composite. In resin injection pultrusion manufacturing the liquid resin is injected into a specially designed tapered injection chamber through the injection slots present on top and bottom of the chamber. The resin is injected at a pressure so as to completely wetout the fiber reinforcements inside the tapered injection chamber. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the center of chamber causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to efficaciously penetrate through the compacted fibers and achieve complete wetout. The impact of resin viscosity on resin flow, fiber compaction, wetout and on the final product is further discussed. Injection chamber design predominantly effects the resin flow inside the chamber and the minimum injection pressure required to completely wet the fibers. Therefore, a desirable injection chamber design is such that wetout occurs at lower injection pressures and at low internal pressures inside the injection chamber.

Resin Viscosity Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

NASA Astrophysics Data System (ADS)

Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

2017-08-01

Viscosity of the liquid resin effects the chemical and mechanical properties of the pultruded composite. In resin injection pultrusion manufacturing the liquid resin is injected into a specially designed tapered injection chamber through the injection slots present on top and bottom of the chamber. The resin is injected at a pressure so as to completely wetout the fiber reinforcements inside the tapered injection chamber. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the center of chamber causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to efficaciously penetrate through the compacted fibers and achieve complete wetout. The impact of resin viscosity on resin flow, fiber compaction, wetout and on the final product is further discussed. Injection chamber design predominantly effects the resin flow inside the chamber and the minimum injection pressure required to completely wet the fibers. Therefore, a desirable injection chamber design is such that wetout occurs at lower injection pressures and at low internal pressures inside the injection chamber.

Testing of machine wound second generation HTS tape Vacuum Pressure Impregnated coils

NASA Astrophysics Data System (ADS)

Swaffield, D.; Lewis, C.; Eugene, J.; Ingles, M.; Peach, D.

2014-05-01

Delamination of second generation (2G) High Temperature Superconducting (HTS) tapes has previously been reported when using resin based insulation systems for wound coils. One proposed root cause is the differential thermal contraction between the coil former and the resin encapsulated coil turns resulting in the tape c-axis tensile stress being exceeded. Importantly, delamination results in unacceptable degradation of the superconductor critical current level. To mitigate the delamination risk and prove winding, jointing and Vacuum Pressure Impregnation (VPI) processes in the production of coils for superconducting rotating machines at GE Power Conversion two scaled trial coils have been wound and extensively tested. The coils are wound from 12mm wide 2G HTS tape supplied by AMSC onto stainless steel 'racetrack' coil formers. The coils are wound in two layers which include both in-line and layer-layer joints subject to in-process test. The resin insulation system chosen is VPI and oven cured. Tests included; insulation resistance, repeat quench and recovery of the superconductor, heat runs and measurement of n-value, before and after multiple thermal cycling between ambient and 35 Kelvin. No degradation of coil performance is evidenced.

An ultrahigh vacuum, low-energy ion-assisted deposition system for III-V semiconductor film growth

NASA Astrophysics Data System (ADS)

Rohde, S.; Barnett, S. A.; Choi, C.-H.

1989-06-01

A novel ion-assisted deposition system is described in which the substrate and growing film can be bombarded with high current densities (greater than 1 mA/sq cm) of very low energy (10-200 eV) ions. The system design philosophy is similar to that used in III-V semiconductor molecular-beam epitaxy systems: the chamber is an all-metal ultrahigh vacuum system with liquid-nitrogen-cooled shrouds, Knudsen-cell evaporation sources, a sample insertion load-lock, and a 30-kV reflection high-energy electron diffraction system. III-V semiconductor film growth is achieved using evaporated group-V fluxes and group-III elemental fluxes sputtered from high-purity targets using ions extracted from a triode glow discharge. Using an In target and an As effusion cell, InAs deposition rates R of 2 microns/h have been obtained. Epitaxial growth of InAs was observed on both GaSb(100) and Si(100) substrates.

Microwave-assisted rapid preparation of monodisperse superhydrophilic resin microspheres as adsorbent for triazines in fruit juices.

PubMed

Zhou, Tianyu; Ding, Jie; Wang, Qiang; Xu, Yuan; Wang, Bo; Zhao, Li; Ding, Hong; Chen, Yanhua; Ding, Lan

2018-03-01

Monodisperse superhydrophilic melamine formaldehyde resorcinol resin (MFR) microspheres were prepared in 90min at 85°C via a microwave-assisted method with a yield of 60.6%. The obtained MFR microspheres exhibited narrow size distribution with the average particle size of about 2.5µm. The MFR microspheres were used as absorbents to detect triazines in juices followed by high performance liquid chromatography tandem mass spectrometry. Various factors affecting the extraction efficiency were investigated. Under the optimized conditions, the built method exhibited excellent linearity in the range of 1-250μgL -1 (R 2 ≥ 0.9994) and lower detection limits (0.3-0.65μgL -1 ). The relative standard deviations of intra- and inter-day analyses ranged from 3% to 7% and from 2% to 7%, respectively. The method was applied to determine six triazines in three juice samples. At the spiked level of 3μgL -1 , the recoveries were in the range of 90-99% with the relative standard deviations ≤ 8%. Copyright © 2017 Elsevier B.V. All rights reserved.

Design and user evaluation of a wheelchair mounted robotic assisted transfer device.

PubMed

Grindle, Garrett G; Wang, Hongwu; Jeannis, Hervens; Teodorski, Emily; Cooper, Rory A

2015-01-01

The aim of this study is to describe the robotic assisted transfer device (RATD) and an initial focus group evaluation by end users. The purpose of the device is to aid in the transfers of people with disabilities to and from their electric powered wheelchair (EPW) onto other surfaces. The device can be used for both stand-pivot transfers and fully dependent transfers, where the person being transferred is in a sling and weight is fully on the robot. The RATD is fixed to an EPW to allow for its use in community settings. A functional prototype of the RATD was designed and fabricated. The prototype was presented to a group of 16 end users and feedback on the device was obtained via a survey and group discussion. Thirteen out of sixteen (83%) participants agreed that it was important to develop this type of technology. They also indicated that user, caregiver, and robotic controls were important features to be included in the device. Participants in this study suggested that they would be accepting the use of robotic technology for transfers and a majority did not feel that they would be embarrassed to use this technology.

Aerosol Vacuum-Assisted Plasma Ionization (Aero-VaPI) Coupled to Ion Mobility-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Blair, Sandra L.; Ng, Nga L.; Zambrzycki, Stephen C.; Li, Anyin; Fernández, Facundo M.

2018-02-01

In this communication, we report on the real-time analysis of organic aerosol particles by Vacuum-assisted Plasma Ionization-Mass Spectrometry (Aero-VaPI-MS) using a home-built VaPI ion source coupled to a Synapt G2-S HDMS ion mobility-mass spectrometry (IM-MS) system. Standards of organic molecules of interest in prebiotic chemistry were used to generate aerosols. Monocaprin and decanoic acid aerosol particles were successfully detected in both the positive and negative ion modes, respectively. A complex aerosol mixture of different sizes of polymers of L-malic acid was also examined through ion mobility (IM) separations, resulting in the detection of polymers of up to eight monomeric units. This noncommercial plasma ion source is proposed as a low cost alternative to other plasma ionization platforms used for aerosol analysis, and a higher-performance alternative to more traditional aerosol mass spectrometers. VaPI provides robust online ionization of organics in aerosols without extensive ion activation, with the coupling to IM-MS providing higher peak capacity and excellent mass accuracy. [Figure not available: see fulltext.

Phenylethynyl Containing Polyarylene Ethers/Polyimides Resin Infiltration of Composites

NASA Technical Reports Server (NTRS)

Dunn, DeRome O.

1998-01-01

The following tasks were performed at NCA&TSU during the second year in performance of the grant. LaRC-LV-1 13 resin was synthesized at NCA&TSU. In order to perform the synthesis, glassware and needed apparatus were purchased with grant funds along with the appropriate monomers. It was found that the LaRC-LV-1 13 resin was easily synthesized by the NMP solvent/toluene imminization/distilled water precipitation process. However, in use this resin exhibited a bubbling/foaming behavior during cure that was detrimental leading to the production of composite panels having a high void content. Composite panels were fabricated using compression molding and resin transfer molding (RTM) techniques. Initial fiber volume determinations were computed at NCA&TSU along with NASA-Langley measured c-scans on the panels produced. The initial results indicated a unsatisfactory level of approximately 20% by volume of voids. Testing of uniaxial coupons in compression to failure also agreed with these results. The uniaxial coupons delaminated as the major mode of failure indicative of an unacceptably low level of resin and to much void content in the final composites produced. In discussions with Dr. Brian Jensen, it was suggested the void fraction needs to be reduced to at least 2% by volume for a useful composite. The panels produced used both resin synthesized at NASA-Langley and NCA&TSU. In reviewing our progress over the past year, it was noted that the resin as formulated by the current synthesis process bubbled at elevated temperature. This was especially observed in neat resin slugs cured at the recommended one, four and eight hour cure temperatures. Pressurized cures where then performed with pressures up to 200 psi and simultaneously the lowest eight hour cure temperatures. Although this procedure reduced the amount of bubbles to some extent in the neat resin slugs it did not completely eliminate them. The cure reaction appears to be very energetic even at the lowest

Transfer molding of PMR-15 polyimide resin

NASA Technical Reports Server (NTRS)

Reardon, J. P.; Moyer, D. W.; Nowak, B. E.

1985-01-01

Transfer molding is an economically viable method of producing small shapes of PMR-15 polyimide. It is shown that with regard to flexural, compressive, and tribological properties transfer-molded PMR-15 polyimide is essentially equivalent to PMR-15 polyimide produced by the more common method of compression molding. Minor variations in anisotropy are predictable effects of molding design and secondary finishing operations.

Thermodynamic performance of multi-stage gradational lead screw vacuum pump

NASA Astrophysics Data System (ADS)

Zhao, Fan; Zhang, Shiwei; Sun, Kun; Zhang, Zhijun

2018-02-01

As a kind of dry mechanical vacuum pump, the twin-screw vacuum pump has an outstanding pumping performance during operation, widely used in the semiconductor industry. Compared with the constant lead screw (CLS) vacuum pump, the gradational lead screw (GLS) vacuum pump is more popularly applied in recent years. Nevertheless, not many comparative studies on the thermodynamic performance of GLS vacuum pump can be found in the literature. Our study focuses on one type of GLS vacuum pump, the multi-stage gradational lead screw (MGLS) vacuum pump, gives a detailed description of its construction and illustrates it with the drawing. Based on the structural analysis, the thermodynamic procedure is divided into four distinctive processes, including sucking process, transferring (compressing) process, backlashing process and exhausting process. The internal mechanism of each process is qualitatively illustrated and the mathematical expressions of seven thermodynamic parameters are given under the ideal situation. The performance curves of MGLS vacuum pump are plotted by MATLAB software and compared with those of the CLS vacuum pump in the same case. The results can well explain why the MGLS vacuum pump has more favorable pumping performance than the CLS vacuum pump in saving energy, reducing noise and heat dissipation.

UV-cured adhesives for carbon fiber composite applications

NASA Astrophysics Data System (ADS)

Lu, Hsiao-Chun

Carbon fiber composite materials are increasingly used in automobile, marine, and aerospace industries due to their unique properties, including high strength, high stiffness and low weight. However, due to their brittle characteristic, these structures are prone to physical damage, such as a bird strike or impact damage. Once the structure is damaged, it is important to have fast and reliable temporary repair until the permanent repair or replacement can take place. In this dissertation, UV-based adhesives were used to provide a bonding strength for temporary repair. Adhesively bonded patch repair is an efficient and effective method for temporary repair. In this study, precured patches (hard patches) and dry fabric patches with laminating resins (soft patches) were performed. UV-based epoxy adhesives were applied to both patch repair systems. For precured patch repair, the bonding strengths were investigated under different surface treatments for bonding area and different adhesives thicknesses. The shear stresses of different UV exposure times and curing times were tested. Besides, the large patch repair was investigated as well. For soft patch repair, the hand wet lay-up was applied due to high viscosity of UV resins. A modified single lap shear testing (ASTM D5868) was applied to determine the shear stress. The large patches used fiber glass instead of carbon fiber to prove the possibility of repair with UV epoxy resin by hand wet lay-up process. The hand lay-up procedure was applied and assisted by vacuum pressure to eliminate the air bubbles and consolidate the patches. To enhance the bonding strength and effective soft patch repair, vacuum assisted resin transferring molding (VaRTM) is the better option. However, only low viscosity resins can be operated by VaRTM. Hence, new UV-based adhesives were formulated. The new UV-based adhesives included photoinitiator (PI), epoxy and different solvents. Solvents were used to compound the photoinitiator into epoxy

Foam, Foam-resin composite and method of making a foam-resin composite

NASA Technical Reports Server (NTRS)

MacArthur, Doug E. (Inventor); Cranston, John A. (Inventor)

1995-01-01

This invention relates to a foam, a foam-resin composite and a method of making foam-resin composites. The foam set forth in this invention comprises a urethane modified polyisocyanurate derived from an aromatic amino polyol and a polyether polyol. In addition to the polyisocyanurate foam, the composite of this invention further contains a resin layer, wherein the resin may be epoxy, bismaleimide, or phenolic resin. Such resins generally require cure or post-cure temperatures of at least 350.degree. F.

The Rivalry between Simulation and Problem-Based Learning: A Study of Learning Transfer in Physician Assistant Students

ERIC Educational Resources Information Center

Meyer, Kimberly E.

2010-01-01

The purpose of this dissertation was to evaluate learning transfer achieved by physician assistant students comparing two instructional methods, human patient simulation and electronic clinical case studies. This prospective, randomized, mixed-methods study utilized first and second-year physician assistant student volunteers taking a pretest and…

Quantitation of buried contamination by use of solvents. Part 1: Solvent degradation of amine cured epoxy resins

NASA Technical Reports Server (NTRS)

Rheineck, A. E.; Heskin, R. A.; Hill, L. W.

1972-01-01

The solubility and/or swelling of cured epoxy resins was studied using the solubility parameter method. Determination of solubility parameters were found in order to select solvents for solvent-assisted degradation of cured epoxy polymers used in spacecraft. A method for improving recovery of seeded spores is suggested for assay of buried contaminants. Three commercial epoxy resins were cured using four different alkyl amines. For each resin-amine combination, three levels of amine were used, corresponding to 1/3, 2/3, and all of the amine required to react with the oxirane groups of the resin. The solubility parameters of the 36 resulting model compounds were determined in poorly and moderately hydrogen-bonded solvents. No strongly hydrogen-bonded solvents caused dissolution or swelling. The tolerance of cured resins is discussed in terms of polymer structure.

41 CFR 102-75.620 - What happens if property that was transferred to meet a self-help housing or housing assistance...

Code of Federal Regulations, 2011 CFR

2011-01-01

... that was transferred to meet a self-help housing or housing assistance use requirement is found to be... PROPERTY 75-REAL PROPERTY DISPOSAL Surplus Real Property Disposal Property for Providing Self-Help Housing Or Housing Assistance § 102-75.620 What happens if property that was transferred to meet a self-help...

Values of pathological analysis of lost tissue fragments in the vacuum canister during a vacuum-assisted stereotactic biopsy of the breast.

PubMed

El Khoury, M; Mesurolle, B; Omeroglu, A; Aldis, A; Kao, E

2013-05-01

Determine values of pathological analysis of the canister content during a vacuum-assisted breast biopsy (VABB). Approval was obtained from the ethical committee. Prospective radiological and pathological analyses of the canister content collected during 231 VABBs performed on 231 patients were carried out. χ(2) test was used to determine predictors on canister pathology. The canister pathology was reported separately in 212 cases. It showed only blood in 78/212 (37%) cases and benign (including high-risk lesions) and malignant results in, respectively, 113/212 (53%) and 21/212 (10%) cases. Respective specimen analysis was benign, including high-risk lesions in 162/212 cases (76%) and malignant in 50/212 (24%) cases. Microcalcifications were documented on canister X-ray in 70/231 (30%) cases. There was significant association between the canister and the specimen pathology (p<0.0001). In none of the cases was microcalcifications seen exclusively in the canister content or pathological upgrading found in the canister content compared with the specimen. Small tissue fragments and microcalcifications may be lost in the canister during a VABB. Nevertheless, our results did not show any significant value for systematic analysis of the canister content. There is no added diagnostic value to retrieval and analysis of tissue lost in the canister during a VABB.

Hydration effect on ion exchange resin irradiated by swift heavy ions and gamma rays

NASA Astrophysics Data System (ADS)

Boughattas, I.; Labed, V.; Gerenton, A.; Ngono-Ravache, Y.; Dannoux-Papin, A.

2018-06-01

Gamma radiolysis of ion exchange resins (IER) is widely studied since the sixties, as a function of different parameters (resin type, dose, atmosphere, water content …). However, to our knowledge, there are very few data concerning hydrogen emission from anionic and cationic resins irradiated at high Linear Energy Transfers (LET). In the present work, we focus on the influence of hydration on hydrogen emission, in anionic and cationic resins irradiated under inert atmosphere using Swift Heavy Ions (SHI) and gamma irradiations. The radiation chemical yield of molecular hydrogen is nonlinear with water content for both resins. The molecular hydrogen production depends first on the water form in IER (free or linked) and second on the solubility of degradation products. Three steps have been observed: at lower water content where G(H2) is stable, at 50%, G(H2) increases due to reactions between water radiolytic species and the resin functional groups and at high water content, G(H2) decreases probably due to its accumulation in water and its consumption by hydroxyl radicals in the supernatant.

[Bonding of visible light cured composite resins to glass ionomer and Cermet cements].

PubMed

Kakaboura, A; Vougiouklakis, G

1990-04-01

The "sandwich" technique involves combination of composite resins to etched glassionomer cements, is used today in restorative dentistry. The purpose of this study is to evaluate the bond strength between several composite resins and glass ionomer or cerment cements. Cylindrical specimens of the cements Ketac-Silver, Ionobond and GC-Lining Ce-ment were inserted in a mold and their flat free surfaces were etched for 30". Cylindrical plastic tubes were set upon each one of these surfaces and filled with the Composite resins Durafill, Brilliant Lux, Estilux posterior, Estilux posterior CVS and Herculite XR. Half of the specimens transferred in tap water for 24 hours and the others after thermocycling in the first month, kept for 4 months. Shear bond strengths were determined in Monsanto Testing Machine and some fractured surfaces were examined under SEM. The results of this investigation indicate that this technique produces bond strengths between composite resins and glassioners and the combination type of resin and type of cement, affects the values of the strength. Glass cermeet--small particle resin provides the most effective strength and glass ionomer--microfill resins the least. Storage time and thermocycling don't significantly effect the bond strength. SEM examination showed that all fracture failures were obtained in the cement while the opposite resin surfaces were covered with particles of the cements.

Manufacturing of a REBCO racetrack coil using thermoplastic resin aiming at Maglev application

NASA Astrophysics Data System (ADS)

Mizuno, Katsutoshi; Ogata, Masafumi; Hasegawa, Hitoshi

2015-11-01

The REBCO coated conductor is a promising technology for the Maglev application in terms of its high critical temperature. The operating temperature of the on-board magnets can be around 40-50 K with the coated conductor. The REBCO coils are cooled by cryocoolers directly, and hence the thermal design of the REBCO coils significantly changes from that of LTS coils. We have developed a novel REBCO coil structure using thermoplastic resin. The coil is not impregnated and the thermoplastic resin is used to bond the coil winding and the heat transfer members, e.g. copper and aluminum plates. The viscosity of the thermoplastic resin is high enough for the thermoplastic resin not to permeate between the turns in the coil. Therefore, the thermal stress does not occur and the risk of degradation is removed. This paper contains the following three topics. First, the thermal resistance of the thermoplastic resin was measured at cryogenic temperature. Then, a small round REBCO coil was experimentally produced. It has been confirmed that the thermoplastic resin does not cause the degradation and, the adhesion between the coil winding and copper plates withstands the thermal stress. Finally, we successfully produced a full-scale racetrack REBCO coil applying the coil structure with the thermoplastic resin.

Carbon nanotube composites prepared by ultrasonically assisted twin screw extrusion

NASA Astrophysics Data System (ADS)

Lewis, Todd

to various degrees. An apparatus for high temperature resin transfer molding (HT-RTM) was designed and built to produce PETI-8 and PETI-330/carbon fabric composite panels. Performance of the panels was tested at various temperatures. The produced panels exhibited low void content in wetted areas and had higher short beam shear properties in comparison with vacuum assisted resin transfer moldings. To investigate the environmental aspects of nanomaterials, a testing apparatus was designed and manufactured to study the effectiveness of particulate respirators at filtering CNTs. Three different grades of respirators were evaluated for their effectiveness to prevent the inhalation of CNTs. Dust masks, commonly used in a processing environment, were found to be highly ineffective at preventing the inhalation of CNTs. However, respirators with a National Institute for Occupational Safety and Health (NIOSH) rating of P95 or greater were shown to prevent the inhalation of CNTs under normal breathing conditions.

Vacuum storage of yellow-poplar pollen

Treesearch

James R. Wilcox

1966-01-01

Vacuum-drying, followed by storage in vacuo or in an inert gas, is effective for storing pollen of many species. It permits storage at room environments without rigid controls of either temperature or humidity, an advantage that becomes paramount during long-distance transfers of pollen when critical storage conditions are impossible to maintain. In...

Fine structure in the transition region: reaction force analyses of water-assisted proton transfers.

PubMed

Yepes, Diana; Murray, Jane S; Santos, Juan C; Toro-Labbé, Alejandro; Politzer, Peter; Jaque, Pablo

2013-07-01

We have analyzed the variation of the reaction force F(ξ) and the reaction force constant κ(ξ) along the intrinsic reaction coordinates ξ of the water-assisted proton transfer reactions of HX-N = Y (X,Y = O,S). The profile of the force constant of the vibration associated with the reactive mode, k ξ (ξ), was also determined. We compare our results to the corresponding intramolecular proton transfers in the absence of a water molecule. The presence of water promotes the proton transfers, decreasing the energy barriers by about 12 - 15 kcal mol(-1). This is due in part to much smaller bond angle changes being needed than when water is absent. The κ(ξ) profiles along the intrinsic reaction coordinates for the water-assisted processes show striking and intriguing differences in the transition regions. For the HS-N = S and HO-N = S systems, two κ(ξ) minima are obtained, whereas for HO-N = O only one minimum is found. The k ξ (ξ) show similar behavior in the transition regions. We propose that this fine structure reflects the degree of synchronicity of the two proton migrations in each case.

Effects of blood contamination on resin-resin bond strength.

PubMed

Eiriksson, Sigurdur O; Pereira, Patricia N R; Swift, Edward J; Heymann, Harald O; Sigurdsson, Asgeir

2004-02-01

Incremental placement and curing of resin composites has been recommended. However, this requires longer operating time, and therefore, increased risk of contamination. The purpose of this study was to evaluate the effects of blood contamination on microtensile bond strengths (microTBS) between resin interfaces and to determine the best decontamination method to re-establish the original resin-resin bond strength. The top surfaces of 64, 4-mm composite blocks (Z-250, Renew, APX, Pertac II) were untreated as the control, or were treated as follows: blood applied and dried on the surface (Treatment 1), blood applied, rinsed, dried (Treatment 2), blood applied, rinsed, and an adhesive applied (Single Bond, One-Step, Clearfil SE, Prompt L-Pop) (Treatment 3). Fresh composite was applied and light-cured in 2-mm increments. After 24 h storage in water, the specimens were sectioned into 0.7-mm thick slabs, trimmed to a cross-sectional area of 1 mm(2), and loaded to failure at a crosshead speed of 1 mm/min using an Instron universal testing machine. Data were analyzed using two-way ANOVA and Fisher's PLSD test (p<0.05). Control values ranged from 45.1 MPa for Pertac II to 71.5 MPa for APX. Untreated blood contamination resulted in resin-resin bond strengths of only 1.0-13.1 MPa. Rinsing raised bond strengths to over 40 MPa for each material. Use of an adhesive further increased bond strengths except for Pertac II. Rinsing blood from contaminated surfaces increases the resin-resin bond strength significantly and the application of an appropriate adhesive increases the bond strength to control levels.

Determination of thermal contact conductance in vacuum-bagged thermoplastic prepreg stacks using infrared thermography

NASA Astrophysics Data System (ADS)

Baumard, Théo; De Almeida, Olivier; Menary, Gary; Le Maoult, Yannick; Schmidt, Fabrice; Bikard, Jérôme

2016-10-01

The infrared heating of a vacuum-bagged, thermoplastic prepreg stack of glass/PA66 was studied to investigate the influence of vacuum level on thermal contact resistance between plies. A higher vacuum level was shown experimentally to decrease the transverse heat transfer efficiency, indicating that considering only the effect of heat conduction at the plies interfaces is not sufficient to predict the temperature distribution. An inverse analysis was used to retrieve the contact resistance coefficients as a function of vacuum pressure.

Application of alkyl polyglycoside surfactant in ultrasonic-assisted extraction followed by macroporous resin enrichment for the separation of vitexin-2″-O-rhamnoside and vitexin from Crataegus pinnatifida leaves.

PubMed

Han, Feng; Guo, Yupin; Gu, Huiyan; Li, Fenglan; Hu, Baozhong; Yang, Lei

2016-02-15

An alkyl polyglycoside (APG) surfactant was used in ultrasonic-assisted extraction to effectively extract vitexin-2″-O-rhamnoside (VOR) and vitexin (VIT) from Crataegus pinnatifida leaves. APG0810 was selected as the surfactant. The extraction process was optimized for ultrasonic power, the APG concentration, ultrasonic time, soaking time, and liquid-solid ratio. The proposed approach showed good recovery (99.80-102.50% for VOR and 98.83-103.19% for VIT) and reproducibility (relative standard deviation, n=5; 3.7% for VOR and 4.2% for VIT) for both components. The proposed sample preparation method is both simple and effective. The use of APG for extraction of key herbal ingredients shows great potential. Ten widely used commercial macroporous resins were evaluated in a screening study to identify a suitable resin for the separation and purification of VOR and VIT. After comparing static and dynamic adsorption and desorption processes, HPD100B was selected as the most suitable resin. After column adsorption and desorption on this resin, the target compounds VOR and VIT can be effectively separated from the APG0810 extraction solution. Recoveries of VOR and VIT were 89.27%±0.42% and 85.29%±0.36%, respectively. The purity of VOR increased from 35.0% to 58.3% and the purity of VIT increased from 12.5% to 19.9%. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of rapid readout biological indicators for 132 degrees C gravity and 132 degrees C vacuum-assisted steam sterilization cycles using a new automated fluorescent reader.

PubMed

Alfa, Michelle J; Olson, Nancy; DeGagne, Pat; Jackson, Michele

2002-07-01

The primary objective of this study was to evaluate fluorescent readout results of Attest 1291 Biological Indicators (BIs) (3M Health Care, St. Paul, MN) and Attest 1296 BI test packs (containing Attest 1292 BIs) using full and fractional cycles compared with the growth data when prolonged incubation (7 days) was included. Gravity displacement and vacuum-assisted steam sterilization cycles were evaluated. A secondary objective of this study was to evaluate the new automated rapid fluorescent reader (Attest 290 Auto Reader). The rapid readout BIs for gravity displacement and vacuum-assisted steam autoclave cycles at 132 degrees C were processed using full (4 minutes) and four fractional cycles that provided 30% to 80% positive results for growth after 24 hours of incubation (48 hours of incubation for Attest 1292 BIs from the Attest 1296 test packs). Sixty of each type of BI were tested for each cycle (300 of each BI type in total). For all full steam sterilization cycles, results of the rapid fluorescent readout and the 24-hour, 48-hour, and 7-day growth tests were negative for all Attest 1291 and 1292 BIs tested. For all fractional cycles, the 24- and 48-hour growth results for the Attest 1291 and 1292 BIs, respectively, were the same as the 7-day growth results. The fractional cycle data indicated that fluorescent rapid readout was a more sensitive indicator than growth. There were rare (0.9%) false-negative results for BIs under fractional cycle conditions and these all correlated with short fractional cycle exposure times. The fluorescent rapid readout results of the 1291 BIs and 1296 BI test packs reliably predict both 24- and 48-hour and 7-day growth. These data support the value of rapid readout BIs for sterilizer monitoring for both the vacuum-assisted and the gravity displacement steam sterilization cycles. The new automated reader requires less manipulation of the BI and makes monitoring user friendly and less prone to user errors.

Simulation Based Low-Cost Composite Process Development at the US Air Force Research Laboratory

NASA Technical Reports Server (NTRS)

Rice, Brian P.; Lee, C. William; Curliss, David B.

2003-01-01

Low-cost composite research in the US Air Force Research Laboratory, Materials and Manufacturing Directorate, Organic Matrix Composites Branch has focused on the theme of affordable performance. Practically, this means that we use a very broad view when considering the affordability of composites. Factors such as material costs, labor costs, recurring and nonrecurring manufacturing costs are balanced against performance to arrive at the relative affordability vs. performance measure of merit. The research efforts discussed here are two projects focused on affordable processing of composites. The first topic is the use of a neural network scheme to model cure reaction kinetics, then utilize the kinetics coupled with simple heat transport models to predict, in real-time, future exotherms and control them. The neural network scheme is demonstrated to be very robust and a much more efficient method that mechanistic cure modeling approach. This enables very practical low-cost processing of thick composite parts. The second project is liquid composite molding (LCM) process simulation. LCM processing of large 3D integrated composite parts has been demonstrated to be a very cost effective way to produce large integrated aerospace components specific examples of LCM processes are resin transfer molding (RTM), vacuum assisted resin transfer molding (VARTM), and other similar approaches. LCM process simulation is a critical part of developing an LCM process approach. Flow simulation enables the development of the most robust approach to introducing resin into complex preforms. Furthermore, LCM simulation can be used in conjunction with flow front sensors to control the LCM process in real-time to account for preform or resin variability.

Vacuum polarization in Coulomb field revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamastil, J., E-mail: zamastil@karlov.mff.cuni.cz; Šimsa, D.

2017-04-15

Simplified derivation of Wichmann–Kroll term is presented. The derivation uses two formulas for hypergeometric functions, but otherwise is elementary. It is found that Laplace transform of the vacuum charge density diverges at zero momentum transfer. This divergence has nothing to do with known ultraviolet divergence. The latter is related to the large momentum behavior of the pertinent integral, while the former to the small momentum behavior. When these divergences are removed, the energy shift caused by vacuum polarization for an ordinary hydrogen obtained here is in an exact agreement with the result obtained by Wichmann and Kroll. Also, for muonicmore » hydrogen the result obtained here reasonably agrees with that given in literature.« less

Optimization of a vacuum chamber for vibration measurements.

PubMed

Danyluk, Mike; Dhingra, Anoop

2011-10-01

A 200 °C high vacuum chamber has been built to improve vibration measurement sensitivity. The optimized design addresses two significant issues: (i) vibration measurements under high vacuum conditions and (ii) use of design optimization tools to reduce operating costs. A test rig consisting of a cylindrical vessel with one access port has been constructed with a welded-bellows assembly used to seal the vessel and enable vibration measurements in high vacuum that are comparable with measurements in air. The welded-bellows assembly provides a force transmissibility of 0.1 or better at 15 Hz excitation under high vacuum conditions. Numerical results based on design optimization of a larger diameter chamber are presented. The general constraints on the new design include material yield stress, chamber first natural frequency, vibration isolation performance, and forced convection heat transfer capabilities over the exterior of the vessel access ports. Operating costs of the new chamber are reduced by 50% compared to a preexisting chamber of similar size and function.

Assessment of solvent capsule-based healing for woven E-glass fibre-reinforced polymers

NASA Astrophysics Data System (ADS)

Manfredi, Erica; Cohades, Amaël; Richard, Inès; Michaud, Véronique

2015-01-01

Vacuum Assisted Resin Infusion Molding (VARIM) with low vacuum pressure difference was used to manufacture woven glass fibre-reinforced epoxy resin plates, with a fibre volume fraction of approx. 50 vol% and containing ethyl phenylacetate (EPA)-filled capsules for self-healing purposes. Capsules were introduced by functionalising the fabrics through manual dispersion. We investigated the capability of autonomously healing delaminations induced by static loading in Mode I and II. Healing did not take place for composite samples; this was attributed to the presence of bare fibres on the crack plane and to the reduction of EPA diffusion into the matrix in the presence of fibres both of which hinder the swelling mechanism responsible for healing the cracks.

Cup detachment during vacuum-assisted vaginal delivery and birth outcome.

PubMed

Krispin, Eyal; Aviram, Amir; Salman, Lina; Chen, Rony; Wiznitzer, Arnon; Gabbay-Benziv, Rinat

2017-11-01

To determine the perinatal outcome associated with cup detachment during vacuum-assisted vaginal delivery (VAVD). A retrospective cohort study of all women attempting VAVD in a tertiary hospital (2012-2014). Singleton-term pregnancies were included. Antepartum fetal death and major fetal structural or chromosomal abnormalities were excluded. Primary outcome was neonatal birth trauma (subgaleal hematoma, subarachnoid hematoma, subdural hematoma, skull fracture, and/or erb's palsy). Secondary outcomes were maternal complications or other neonatal morbidities. Outcomes were compared between women after ≥1 cup detachment (study group) and the rest (control group). Logistic regression analysis was utilized to adjust results to potential confounders. Overall, 1779 women attempted VAVD during study period. Of them, in 146 (8.2%), the cup detached prior to delivery; 130/146 (89%) had a single detachment. After detachment, 4 (2.7%) delivered by cesarean section, 77 (52.7%) delivered after cup reapplication, and 65 (44.6%) delivered spontaneously. Women in the study group were more likely to undergo VAVD due to prolonged second stage, and were characterized by lower rates of metal cup use. Neonates in the detachment group had higher rates of subarachnoid hematoma and composite neonatal birth trauma (2.7 vs. 0.1% and 4.8 vs. 1.8%, respectively, p < 0.05). This remained significant after adjustment to potential confounders (subarachnoid hematoma aOR = 45.44, 95% CI 6.42-321.62 and neonatal birth trauma aOR = 2.62, 95% CI 1.1-6.22, p < 0.05 for all). Other neonatal and maternal morbidities were similar between groups. Cup detachment is associated with a higher rate of adverse neonatal outcome. Cup reapplication should be considered carefully.

In-office bleaching efficacy on stain removal from CAD/CAM and direct resin composite materials.

PubMed

Alharbi, Amal; Ardu, Stefano; Bortolotto, Tissiana; Krejci, Ivo

2018-01-01

To evaluate the efficacy of in-office bleaching on stain removal from stained resin composite and ceramic computer-assisted design/computer-assisted manufacturing (CAD/CAM) blocks and direct resin composites. Forty disk-shaped samples were fabricated from each of nine materials: six CAD/CAM (VITABLOCS Mark II, Paradigm MZ100, Exp Vita Hybrid Ceramic, VITA ENAMIC, Exp Kerr, and LAVA Ultimate) and three direct resin composites (Filtek Supreme, Venus Diamond, and Filtek Silorane). Samples were randomly divided into five groups (n = 8), each stained with a particular staining solution. Using a calibrated spectrophotometer and a black background, L*a*b* values were assessed before and after 120 days of staining. Samples were subjected to in-office bleaching using 40% hydrogen peroxide gel for one hour. At subsequent assessment, color change (ΔE) was calculated as the difference between L*a*b* values. Both ANOVA and the Duncan test were used to identify differences between groups (α = 0.05). Bleaching resulted in significant differences in ΔE values for all materials (P < .001). Bleaching efficacy was highly influenced by material composition and staining solution. Residual color values after bleaching for ceramic and hybrid ceramics ranged from -0.49 to 2.35, within the clinically acceptable maximum of 3.3. Values after bleaching for resin-based CAD/CAM ranged from -0.7 to 7.08 while direct resin composites values ranged from -1.47 to 25.13. Coffee left the greatest residual color on all materials. Based on material nature, 40% hydrogen peroxide bleaching can remove staining. The new resin-based CAD/CAM blocks showed promising results in terms of color stability. Bleaching using 40% hydrogen peroxide can be an effective method to remove stains from dental restorations. In this way, restoration replacement as a result of discoloration may no longer be necessary. © 2017 Wiley Periodicals, Inc.

Cosmological implications of the transition from the false vacuum to the true vacuum state

NASA Astrophysics Data System (ADS)

Stachowski, Aleksander; Szydłowski, Marek; Urbanowski, Krzysztof

2017-06-01

We study cosmology with running dark energy. The energy density of dark energy is obtained from the quantum process of transition from the false vacuum state to the true vacuum state. We use the Breit-Wigner energy distribution function to model the quantum unstable systems and obtain the energy density of the dark energy parametrization ρ _ {de}(t). We also use Krauss and Dent's idea linking properties of the quantum mechanical decay of unstable states with the properties of the observed Universe. In the cosmological model with this parametrization there is an energy transfer between dark matter and dark energy. The intensity of this process, measured by a parameter α , distinguishes two scenarios. As the Universe starts from the false vacuum state, for the small value of α (0<α <0.4) it goes through an intermediate oscillatory (quantum) regime of the density of dark energy, while for α > 0.4 the density of the dark energy jumps down. In both cases the present value of the density of dark energy is reached. From a statistical analysis we find this model to be in good agreement with the astronomical data and practically indistinguishable from the Λ CDM model.

Vacuum force

NASA Astrophysics Data System (ADS)

Han, Yongquan

2015-03-01

To study on vacuum force, we must clear what is vacuum, vacuum is a space do not have any air and also ray. There is not exist an absolute the vacuum of space. The vacuum of space is relative, so that the vacuum force is relative. There is a certain that vacuum vacuum space exists. In fact, the vacuum space is relative, if the two spaces compared to the existence of relative vacuum, there must exist a vacuum force, and the direction of the vacuum force point to the vacuum region. Any object rotates and radiates. Rotate bend radiate- centripetal, gravity produced, relative gravity; non gravity is the vacuum force. Gravity is centripetal, is a trend that the objects who attracted wants to Centripetal, or have been do Centripetal movement. Any object moves, so gravity makes the object curve movement, that is to say, the radiation range curve movement must be in the gravitational objects, gravity must be existed in non vacuum region, and make the object who is in the region of do curve movement (for example: The earth moves around the sun), or final attracted in the form gravitational objects, and keep relatively static with attract object. (for example: objects on the earth moves but can't reach the first cosmic speed).

Modeling and Analysis of Alternative Concept of ITER Vacuum Vessel Primary Heat Transfer System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carbajo, Juan J; Yoder Jr, Graydon L; Dell'Orco, Giovanni

2010-01-01

A RELAP5-3D model of the ITER (Latin for the way ) vacuum vessel (VV) primary heat transfer system has been developed to evaluate a proposed design change that relocates the heat exchangers (HXs) from the exterior of the tokamak building to the interior. This alternative design protects the HXs from external hazards such as wind, tornado, and aircraft crash. The proposed design integrates the VV HXs into a VV pressure suppression system (VVPSS) tank that contains water to condense vapour in case of a leak into the plasma chamber. The proposal is to also use this water as the ultimatemore » sink when removing decay heat from the VV system. The RELAP5-3D model has been run under normal operating and abnormal (decay heat) conditions. Results indicate that this alternative design is feasible, with no effects on the VVPSS tank under normal operation and with tank temperature and pressure increasing under decay heat conditions resulting in a requirement to remove steam generated if the VVPSS tank low pressure must be maintained.« less

Preparative Separation and Purification of the Total Flavonoids in Scorzonera austriaca with Macroporous Resins.

PubMed

Xie, Yang; Guo, Qiu-Shi; Wang, Guang-Shu

2016-06-13

The use of macroporous resins for the separation and purification of total flavonoids to obtain high-purity total flavonoids from Scorzonera austriaca was studied. The optimal conditions for separation and purification of total flavonoids in S. austriaca with macroporous resins were as follows: D4020 resin columns were loaded with crude flavonoid extract solution, and after reaching adsorptive saturation, the columns were eluted successively with 5 bed volumes (BV) of water, 5 BV of 5% (v/v) aqueous ethanol and 5 BV of 30% (v/v) aqueous ethanol at an elute flow rate of 2 BV·h(-1). Total flavonoids were obtained from the 30% aqueous ethanol eluate by vacuum distillation recovery. The content of flavonoid compounds in the total flavonoids was 93.5%, which represents an improvement by about 150%. In addition, five flavonoid compounds in the product were identified as 2″-O-β-d-xylopyranosyl isoorientin, 6-C-α-l-arabipyranosyl orientin, orientin, isoorientin and vitexin by LC-ESI-MS analysis and internal standard methods. The results in this study could represent a method for the large-scale production of total flavonoids from S. austriaca.

Mixed Matrix Carbon Molecular Sieve and Alumina (CMS-Al2O3) Membranes

NASA Astrophysics Data System (ADS)

Song, Yingjun; Wang, David K.; Birkett, Greg; Martens, Wayde; Duke, Mikel C.; Smart, Simon; Diniz da Costa, João C.

2016-07-01

This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation of carbon molecular sieve (CMS) structures, reaching the lowest average pore sizes of ~5 Å at carbonisation temperatures of 700 °C. The combination of vacuum-assisted impregnation and carbonisation led to the formation of mixed matrix of CMS and α-alumina particles (CMS-Al2O3) in a single membrane. These membranes were tested for pervaporative desalination and gave very high water fluxes of up to 25 kg m-2 h-1 for seawater (NaCl 3.5 wt%) at 75 °C. Salt rejection was also very high varying between 93-99% depending on temperature and feed salt concentration. Interestingly, the water fluxes remained almost constant and were not affected as feed salt concentration increased from 0.3, 1 and 3.5 wt%.

Mixed Matrix Carbon Molecular Sieve and Alumina (CMS-Al2O3) Membranes.

PubMed

Song, Yingjun; Wang, David K; Birkett, Greg; Martens, Wayde; Duke, Mikel C; Smart, Simon; Diniz da Costa, João C

2016-07-29

This work shows mixed matrix inorganic membranes prepared by the vacuum-assisted impregnation method, where phenolic resin precursors filled the pore of α-alumina substrates. Upon carbonisation, the phenolic resin decomposed into several fragments derived from the backbone of the resin matrix. The final stages of decomposition (>650 °C) led to a formation of carbon molecular sieve (CMS) structures, reaching the lowest average pore sizes of ~5 Å at carbonisation temperatures of 700 °C. The combination of vacuum-assisted impregnation and carbonisation led to the formation of mixed matrix of CMS and α-alumina particles (CMS-Al2O3) in a single membrane. These membranes were tested for pervaporative desalination and gave very high water fluxes of up to 25 kg m(-2) h(-1) for seawater (NaCl 3.5 wt%) at 75 °C. Salt rejection was also very high varying between 93-99% depending on temperature and feed salt concentration. Interestingly, the water fluxes remained almost constant and were not affected as feed salt concentration increased from 0.3, 1 and 3.5 wt%.

Ambient Profiling of Phenolic Content in Tea Infusions by Matrix-Assisted Ionization in Vacuum

NASA Astrophysics Data System (ADS)

Cody, Robert B.

2018-05-01

Matrix-assisted ionization in vacuum (MAIV) was used to analyze the polyphenol content of ten different tea infusions. Nine different Camellia sinensis infusions were analyzed including three green teas, two black teas, two oolong teas, jasmine tea, and white tea. An infusion of rooibos (Aspalathus linearis) tea was also analyzed. Each freshly brewed tea was diluted 1:1 with methanol, and 100 ppm of phenolphthalein was added as an internal standard. An excess of 3-nitrobenzonitrile (NBN) was added to each vial, and the solution containing NBN crystals was analyzed by aspiration directly into the mass spectrometer sampling orifice. A working curve constructed for dilutions of catechin with phenolphthalein internal standard showed good linearity for five replicates of each concentration. The measured relative abundances of flavonoid polyphenols in each tea were in good agreement with previously reported values. Polyphenol content in tea infusions varied from 19.2 to 108.6 mg 100 mL-1. In addition to the expected catechin flavonoids, abundant quinic acid and gallic acid was detected in the C. sinensis infusions. Characteristic A. linearis flavonoids were detected in the rooibos tea.

Verification of a two-dimensional infiltration model for the resin transfer molding process

NASA Technical Reports Server (NTRS)

Hammond, Vincent H.; Loos, Alfred C.; Dexter, H. Benson; Hasko, Gregory H.

1993-01-01

A two-dimensional finite element model for the infiltration of a dry textile preform by an injected resin was verified. The model, which is based on the finite element/control volume technique, determines the total infiltration time and the pressure increase at the mold inlet associated with the RTM process. Important input data for the model are the compaction and permeability behavior of the preform along with the kinetic and rheological behavior of the resin. The compaction behavior for several textile preforms was determined by experimental methods. A power law regression model was used to relate fiber volume fraction to the applied compaction pressure. Results showed a large increase in fiber volume fraction with the initial application of pressure. However, as the maximum fiber volume fraction was approached, the amount of compaction pressure required to decrease the porosity of the preform rapidly increased. Similarly, a power law regression model was used to relate permeability to the fiber volume fraction of the preform. Two methods were used to measure the permeability of the textile preform. The first, known as the steady state method, measures the permeability of a saturated preform under constant flow rate conditions. The second, denoted the advancing front method, determines the permeability of a dry preform to an infiltrating fluid. Water, corn oil, and an epoxy resin, Epon 815, were used to determine the effect of fluid type and viscosity on the steady state permeability behavior of the preform. Permeability values measured with the different fluids showed that fluid viscosity had no influence on the permeability behavior of 162 E-glass and TTI IM7/8HS preforms. Permeabilities measured from steady state and advancing front experiments for the warp direction of 162 E-glass fabric were similar. This behavior was noticed for tests conducted with corn oil and Epon 815. Comparable behavior was observed for the warp direction of the TTI IM7/8HS preform

Abdominal wall integrity after open abdomen: long-term results of vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM).

PubMed

Willms, A; Schaaf, S; Schwab, R; Richardsen, I; Bieler, D; Wagner, B; Güsgen, C

2016-12-01

The open abdomen has become a standard technique in the management of critically ill patients undergoing surgery for severe intra-abdominal conditions. Negative pressure and mesh-mediated fascial traction are commonly used and achieve low fistula rates and high fascial closure rates. In this study, long-term results of a standardised treatment approach are presented. Fifty-five patients who underwent OA management for different indications at our institution from 2006 to 2013 were enrolled. All patients were treated under a standardised algorithm that uses a combination of vacuum-assisted wound closure and mesh-mediated fascial traction. Structured follow-up assessments were offered to patients and included a medical history, a clinical examination and abdominal ultrasonography. The data obtained were statistically analysed. The fascial closure rate was 74 % in an intention-to-treat analysis and 89 % in a per-protocol analysis. The fistula rate was 1.8 %. Thirty-four patients attended follow-up. The median follow-up was 46 months (range 12-88 months). Incisional hernias developed in 35 %. Patients with hernias needed more operative procedures (10.3 vs 3.4, p = 0.03) than patients without hernia formation. A Patient Observer Scar Assessment Scale (POSAS) of 31.1 was calculated. Patients with symptomatic hernias (NAS of 2-10) had a significantly lower mean POSAS score (p = 0.04). Vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM) seem to result in low complication rates and high fascial closure rates. Abdominal wall reconstruction, which is a challenging and complex procedure and causes considerable patient discomfort, can thus be avoided in the majority of cases. Available results are based on studies involving only a small number of cases. Multi-centre studies and registry-based data are therefore needed to validate these findings.

Direct dry transfer of CVD graphene to an optical substrate by in situ photo-polymerization

NASA Astrophysics Data System (ADS)

Kessler, Felipe; Muñoz, Pablo A. R.; Phelan, Ciaran; Romani, Eric C.; Larrudé, Dunieskys R. G.; Freire, Fernando L.; Thoroh de Souza, Eunézio A.; de Matos, Christiano J. S.; Fechine, Guilhermino J. M.

2018-05-01

Here, we report on a method that allows graphene produced by chemical vapor deposition (CVD) to be directly transferred to an optically transparent photo resin, by in situ photo-polymerization of the latter, with high efficiency and low contamination. Two photocurable resins, A and B, with different viscosities but essentially the same chemical structure, were used. Raman spectroscopy and surface energy results show that large continuous areas of graphene were transferred with minimal defects to the lower viscosity resin (B), due to the better contact between the resin and graphene. As a proof-of-principle optical experiment, graphene on the polymeric substrate was subjected to high-intensity femtosecond infrared pulses and third-harmonic generation was observed with no noticeable degradation of the sample. A sheet third-order susceptibility χ (3) = 0.71 ×10-28m3V-2 was obtained, matching that of graphene on a glass substrate. These results indicate the suitability of the proposed transfer method, and of the photo resin, for the production of nonlinear photonic components and devices.

Vacuum-driven power-free microfluidics utilizing the gas solubility or permeability of polydimethylsiloxane (PDMS).

PubMed

Xu, Linfeng; Lee, Hun; Jetta, Deekshitha; Oh, Kwang W

2015-10-21

Suitable pumping methods for flow control remain a major technical hurdle in the path of biomedical microfluidic systems for point-of-care (POC) diagnostics. A vacuum-driven power-free micropumping method provides a promising solution to such a challenge. In this review, we focus on vacuum-driven power-free microfluidics based on the gas solubility or permeability of polydimethylsiloxane (PDMS); degassed PDMS can restore air inside itself due to its high gas solubility or gas permeable nature. PDMS allows the transfer of air into a vacuum through it due to its high gas permeability. Therefore, it is possible to store or transfer air into or through the gas soluble or permeable PDMS in order to withdraw liquids into the embedded dead-end microfluidic channels. This article provides a comprehensive look at the physics of the gas solubility and permeability of PDMS, a systematic review of different types of vacuum-driven power-free microfluidics, and guidelines for designing solubility-based or permeability-based PDMS devices, alongside existing applications. Advanced topics and the outlook in using micropumping that utilizes the gas solubility or permeability of PDMS will be also discussed. We strongly recommend that microfluidics and lab-on-chip (LOC) communities harness vacuum energy to develop smart vacuum-driven microfluidic systems.

Phenoxy resins containing pendent ethynyl groups and cured resins obtained therefrom

NASA Technical Reports Server (NTRS)

Hergenrother, P. M. (Inventor)

1985-01-01

Phenoxy resins containing pendent ethynyl groups, the process for preparing the same, and the cured resin products obtained therefrom are disclosed. Upon the application of heat, the ethynyl groups react to provide branching and crosslinking with the cure temperature being lowered by using a catalyst if desired but not required. The cured phenoxy resins containing pendent ethynyl groups have improved solvent resistance and higher use temperature than linear uncrosslinked phenoxy resins and are applicable for use as coatings, films, adhesives, composited matrices and molding compounds.

Surface enhanced Raman scattering of aged graphene: Effects of annealing in vacuum

NASA Astrophysics Data System (ADS)

Wang, Yingying; Ni, Zhenhua; Li, Aizhi; Zafar, Zainab; Zhang, Yan; Ni, Zhonghua; Qu, Shiliang; Qiu, Teng; Yu, Ting; Xiang Shen, Ze

2011-12-01

In this paper, we report a simple method to recover the surface enhanced Raman scattering activity of aged graphene. The Raman signals of Rhodamine molecules absorbed on aged graphene are dramatically increased after vacuum annealing and comparable to those on fresh graphene. Atomic force microscopy measurements indicate that residues on aged graphene surface can efficiently be removed by vacuum annealing, which makes target molecule closely contact with graphene. We also find that the hole doping in graphene will facilitate charge transfer between graphene and molecule. These results confirm the strong Raman enhancement of target molecule absorbed on graphene is due to the charge transfer mechanism.

Vacuum-induced quantum memory in an opto-electromechanical system

NASA Astrophysics Data System (ADS)

Qin, Li-Guo; Wang, Zhong-Yang; Wu, Shi-Chao; Gong, Shang-Qing; Ma, Hong-Yang; Jing, Jun

2018-03-01

We propose a scheme to implement electrically controlled quantum memory based on vacuum-induced transparency (VIT) in a high-Q tunable cavity, which is capacitively coupled to a mechanically variable capacitor by a charged mechanical cavity mirror as an interface. We analyze the changes of the cavity photons arising from vacuum-induced-Raman process and discuss VIT in an atomic ensemble trapped in the cavity. By slowly adjusting the voltage on the capacitor, the VIT can be adiabatically switched on or off, meanwhile, the transfer between the probe photon state and the atomic spin state can be electrically and adiabatically modulated. Therefore, we demonstrate a vacuum-induced quantum memory by electrically manipulating the mechanical mirror of the cavity based on electromagnetically induced transparency mechanism.

An experimental study of permeability within an out-of-autoclave vacuum-bag-only CFRP laminate

NASA Astrophysics Data System (ADS)

Wallace, Landon F.

The out-of-autoclave vacuum-bag-only (OOA-VBO) manufacturing process is a process that eliminates an autoclave when manufacturing aerospace quality carbon fiber reinforced plastics (CFRP). OOA-VBO pre-impregnated resin tow systems rely on air channel networks that guide unwanted voids out of the laminate. The air path networks can be characterized by measuring the permeability of a pre-cured laminate. Permeability results were successfully obtained for a laminate with a compaction similar to that found in a typical vacuum bagging setup. A study was done to find the relationship between compaction of the laminate and permeability. Permeability was measured as the laminate cured, using a constant temperature ramp rate. An experimental nodal analysis was performed to find the permeability at the midpoint of the in-plane direction.

Denitrogenation model for vacuum tank degasser

NASA Astrophysics Data System (ADS)

Gobinath, R.; Vetrivel Murugan, R.

2018-02-01

Nitrogen in steel is both beneficial and detrimental depending on grade of steel and its application. To get desired low nitrogen during vacuum degassing process, VD parameters namely vacuum level, argon flow rate and holding time has to optimized depending upon initial nitrogen level. In this work a mathematical model to simulate nitrogen removal in tank degasser is developed and how various VD parameters affects nitrogen removal is studied. Ladle water model studies with bottom purging have shown two distinct flow regions, namely the plume region and the outside plume region. The two regions are treated as two separate reactors exchanging mass between them and complete mixing is assumed in both the reactors. In the plume region, transfer of nitrogen to single bubble is simulated. At the gas-liquid metal interface (bubble interface) thermodynamic equilibrium is assumed and the transfer of nitrogen from bulk liquid metal in the plume region to the gas-metal interface is obtained using mass transport principles. The model predicts variation of Nitrogen content in both the reactors with time. The model is validated with industrial process and the predicted results were found to have fair agreement with the measured results.

Resin-Powder Dispenser

NASA Technical Reports Server (NTRS)

Standfield, Clarence E.

1994-01-01

Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

Thermal conductivity model for powdered materials under vacuum based on experimental studies

NASA Astrophysics Data System (ADS)

Sakatani, N.; Ogawa, K.; Iijima, Y.; Arakawa, M.; Honda, R.; Tanaka, S.

2017-01-01

The thermal conductivity of powdered media is characteristically very low in vacuum, and is effectively dependent on many parameters of their constituent particles and packing structure. Understanding of the heat transfer mechanism within powder layers in vacuum and theoretical modeling of their thermal conductivity are of great importance for several scientific and engineering problems. In this paper, we report the results of systematic thermal conductivity measurements of powdered media of varied particle size, porosity, and temperature under vacuum using glass beads as a model material. Based on the obtained experimental data, we investigated the heat transfer mechanism in powdered media in detail, and constructed a new theoretical thermal conductivity model for the vacuum condition. This model enables an absolute thermal conductivity to be calculated for a powder with the input of a set of powder parameters including particle size, porosity, temperature, and compressional stress or gravity, and vice versa. Our model is expected to be a competent tool for several scientific and engineering fields of study related to powders, such as the thermal infrared observation of air-less planetary bodies, thermal evolution of planetesimals, and performance of thermal insulators and heat storage powders.

Three-Dimensional Analysis of Internal Adaptations of Crowns Cast from Resin Patterns Fabricated Using Computer-Aided Design/Computer-Assisted Manufacturing Technologies.

PubMed

Liu, Yushu; Ye, Hongqiang; Wang, Yong; Zhao, Yijao; Sun, Yuchun; Zhou, Yongsheng

2018-05-17

To evaluate the internal adaptations of cast crowns made from resin patterns produced using three different computer-aided design/computer-assisted manufacturing technologies. A full-crown abutment made of zirconia was digitized using an intraoral scanner, and the design of the crown was finished on the digital model. Resin patterns were fabricated using a fused deposition modeling (FDM) 3D printer (LT group), a digital light projection (DLP) 3D printer (EV group), or a five-axis milling machine (ZT group). All patterns were cast in cobalt-chromium alloy crowns. Crowns made from traditional handmade wax patterns (HM group) were used as controls. Each group contained 10 samples. The internal gaps of the patterns were analyzed using a 3D replica method and optical digitization. The results were compared using Kruskal-Wallis analysis of variance (ANOVA), a one-sample t test, and signed rank test (α = .05). For the LT group, the marginal and axial gaps were significantly larger than in the other three groups (P < .05), but the occlusal adaptation did not reveal a significant difference (P > .05). In the ZT group, the axial gap was slightly smaller than in the HM group (P < .0083). All the means of gaps in all areas in the four groups were less than 150 μm. Casting crowns using casting patterns made from all three CAD/CAM systems could not produce the prescribed parameters, but the crowns showed clinically acceptable internal adaptations.

Microwave-synthesized freestanding iron-carbon nanotubes on polyester composites of woven Kevlar fibre and silver nanoparticle-decorated graphene

PubMed Central

Hazarika, Ankita; Deka, Biplab K.; Kim, DoYoung; Kong, Kyungil; Park, Young-Bin; Park, Hyung Wook

2017-01-01

We synthesized Ag nanoparticle-decorated multilayered graphene nanosheets (Ag-graphene) from graphite nanoplatelets and silver nitrate through 90–100 s of microwave exposure, without the use of any mineral acids or harsh reducing agents. Fe nanoparticle-decorated carbon nanotubes (Fe-CNTs) were grown on polypyrrole (PPy) deposited on woven Kevlar fibre (WKF), using ferrocene as a catalyst, under microwave irradiation. Fe-CNTs grown on WKF and Ag-graphene dispersed in polyester resin (PES) were combined to fabricate Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites by vacuum-assisted resin transfer moulding. The combined effect of Fe-CNTs and Ag-graphene in the resulting composites resulted in a remarkable enhancement of tensile properties (a 192.56% increase in strength and 100.64% increase in modulus) as well as impact resistance (a 116.33% increase). The electrical conductivity significantly increased for Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites. The effectiveness of electromagnetic interference shielding, which relies strongly on the Ag-graphene content in the composites, was 25 times higher in Ag-graphene/Fe-CNT/PPy-coated WKF/PES than in neat WKF/PES composites. The current work offers a novel route for fabricating highly promising, cost effective WKF/PES composites through microwave-assisted synthesis of Fe-CNTs and Ag-graphene. PMID:28074877

Microwave-synthesized freestanding iron-carbon nanotubes on polyester composites of woven Kevlar fibre and silver nanoparticle-decorated graphene

NASA Astrophysics Data System (ADS)

Hazarika, Ankita; Deka, Biplab K.; Kim, Doyoung; Kong, Kyungil; Park, Young-Bin; Park, Hyung Wook

2017-01-01

We synthesized Ag nanoparticle-decorated multilayered graphene nanosheets (Ag-graphene) from graphite nanoplatelets and silver nitrate through 90-100 s of microwave exposure, without the use of any mineral acids or harsh reducing agents. Fe nanoparticle-decorated carbon nanotubes (Fe-CNTs) were grown on polypyrrole (PPy) deposited on woven Kevlar fibre (WKF), using ferrocene as a catalyst, under microwave irradiation. Fe-CNTs grown on WKF and Ag-graphene dispersed in polyester resin (PES) were combined to fabricate Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites by vacuum-assisted resin transfer moulding. The combined effect of Fe-CNTs and Ag-graphene in the resulting composites resulted in a remarkable enhancement of tensile properties (a 192.56% increase in strength and 100.64% increase in modulus) as well as impact resistance (a 116.33% increase). The electrical conductivity significantly increased for Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites. The effectiveness of electromagnetic interference shielding, which relies strongly on the Ag-graphene content in the composites, was 25 times higher in Ag-graphene/Fe-CNT/PPy-coated WKF/PES than in neat WKF/PES composites. The current work offers a novel route for fabricating highly promising, cost effective WKF/PES composites through microwave-assisted synthesis of Fe-CNTs and Ag-graphene.

Microwave-synthesized freestanding iron-carbon nanotubes on polyester composites of woven Kevlar fibre and silver nanoparticle-decorated graphene.

PubMed

Hazarika, Ankita; Deka, Biplab K; Kim, DoYoung; Kong, Kyungil; Park, Young-Bin; Park, Hyung Wook

2017-01-11

We synthesized Ag nanoparticle-decorated multilayered graphene nanosheets (Ag-graphene) from graphite nanoplatelets and silver nitrate through 90-100 s of microwave exposure, without the use of any mineral acids or harsh reducing agents. Fe nanoparticle-decorated carbon nanotubes (Fe-CNTs) were grown on polypyrrole (PPy) deposited on woven Kevlar fibre (WKF), using ferrocene as a catalyst, under microwave irradiation. Fe-CNTs grown on WKF and Ag-graphene dispersed in polyester resin (PES) were combined to fabricate Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites by vacuum-assisted resin transfer moulding. The combined effect of Fe-CNTs and Ag-graphene in the resulting composites resulted in a remarkable enhancement of tensile properties (a 192.56% increase in strength and 100.64% increase in modulus) as well as impact resistance (a 116.33% increase). The electrical conductivity significantly increased for Ag-graphene/Fe-CNT/PPy-coated WKF/PES composites. The effectiveness of electromagnetic interference shielding, which relies strongly on the Ag-graphene content in the composites, was 25 times higher in Ag-graphene/Fe-CNT/PPy-coated WKF/PES than in neat WKF/PES composites. The current work offers a novel route for fabricating highly promising, cost effective WKF/PES composites through microwave-assisted synthesis of Fe-CNTs and Ag-graphene.

[Application research of presacral space drainage tube combined with subcutaneous vacuum pressure suction in the laparoscopic-assisted abdominoperineal resection].

PubMed

Chen, Liqi; Zeng, Changqing; Chi, Liangjie; Huang, Liangxiang; Li, Jiandang

2017-08-25

To study the management for the perineal incision after laparoscopic-assisted abdominoperineal resection for rectal cancer. Clinical data of 87 patients undergoing laparoscopic Miles operation for lower rectal cancer from June 2009 to February 2014 were collected and studied. Presacral space drainage group: presacral space drainage tube was applied in 42 patients. Combined drainage group: presacral space drainage tube combined with subcutaneous vacuum pressure suction was applied in 45 cases. In combined drainage group, except the presacral drainage tube, another drainage tube was placed subcutaneously and connected to a negative pressure ball, which was fixed on the lateral anterior of perineal wound by the further incision and drainage. After subcutaneous tube was placed for 2 weeks, as drainage fluid was limpid and <15 ml/d for 3 days, meanwhile no obvious pelvic fluid was detected by ultrasound, and the wound healed quite well without redness and edema, then the subcutaneous tube with the negative pressure ball could be removed. There were 51 males and 36 females with the mean age of 26-78(56.9±10.8) years old. The laparoscopic Miles operation was successfully completed in all the cases without death and complications. The drainage tube was placed for 4-13(8.0±2.5) days in presacral space drainage group, and for 4-14(6.7±2.4) days in combined drainage group. The subcutaneous tube was placed for 14-24(15.8±3.0) days. The primary healing rate of perineal wound in presacral space drainage group and combined drainage group was 66.7%(28/42) and 91.1%(41/45) respectively, while the perineal wound infection rate was 21.4%(9/42) and 4.4%(2/45) respectively, whose differences between two groups were both significant (χ 2 =7.911, P=0.005 and χ 2 =5.674, P=0.017). Presacral space drainage tube combined with subcutaneous vacuum pressure suction in laparoscopic-assisted abdominoperineal resection for rectal cancer has better efficacy and lower infection rate for

Phenylethynyl Terminated Imide (PETI) Composites Made by High Temperature VARTM

NASA Technical Reports Server (NTRS)

Chose, Sayata; Cano, Roberto J.; Britton, Sean M.; Watson, Kent A.; Jensen, Brian J.; Connell, John W.

2010-01-01

Fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, a void fraction of <2% is desired. In the current study, two PETI resins, LARC. PETI-330 and LARC. PETI-8 have been used to fabricate test specimens using HT-VARTM. The resins were infused into carbon fiber preforms at 260 C and cured between 316 and 371 C. Photomicrographs of the panels were taken and void contents were determined by acid digestion. Modifications to the thermal cycle used in the laminate fabrication have reduced the void content significantly; typically .3% for carbon fiber biaxially woven fabric and less than 2% for carbon fiber uniaxial fabric. Mechanical properties (short beam shear and flexure) of the panels were determined at both room and elevated temperatures. The results of this work are presented herein. This paper is declared a work of the U.S. Government and is not subject to copyright protection in the United States.

Processing and Characterization of PETI Composites Fabricated by High Temperature VARTM

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Cano, Roberto J.; Watson, Kent A.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Smith, Joseph G.; Loos, Alfred C.; Heider, Dirk

2011-01-01

The use of composites as primary structures on aerospace vehicles has increased dramatically over the past decade. As these advanced structures increase in size and complexity, their production costs have grown significantly. A major contributor to these manufacturing costs is the requirement of elevated processing pressures, during the thermal cure, to create fully consolidated composites. For certain composite parts, high temperature vacuum assisted resin transfer molding (HT-VARTM) can offer reduced fabrication costs compared to conventional autoclave techniques. The process has been successfully used with phenylethynyl terminated imide (PETI) resins developed by NASA LaRC. In the current study, two PETI resins, LARC(TradeMark) PETI-330 and LARC(TradeMark) PETI-8 have been used to make test specimens using HT-VARTM. Based on previous work at NASA LaRC, larger panels with a quasi-isotropic lay-up were fabricated. The resultant composite specimens exhibited void contents <3% by volume depending on the type of carbon fabric preform used. Mechanical properties of the panels were determined at both room and elevated temperatures. These included open-hole compressive (OHC) and short beam shear (SBS) properties. Limited process modeling efforts were carried out including infusion times, composite panel size limitations and fabric permeability characterization. Work has also been carried out to develop new PETI based resins specifically geared towards HT-VARTM. The results of this work are presented herein.

Sonographically-guided vacuum-assisted biopsy with digital mammography-guided skin marking of suspicious breast microcalcifications: comparison of outcomes with stereotactic biopsy in Asian women.

PubMed

Hahn, Soo Yeon; Shin, Jung Hee; Han, Boo-Kyung; Ko, Eun Young

2011-02-01

Management of suspicious microcalcifications in very thin breasts is problematic. To evaluate whether sonographically-guided vacuum-assisted biopsy (USVAB) with digital mammography-guided skin marking (DM) for the diagnosis of breast microcalcifications is comparable to stereotactic-guided vacuum-assisted biopsy (SVAB) in Asian women with thin breasts. Retrospective review was performed for 263 consecutive suspicious microcalcification lesions in 261 women who underwent USVAB with DM or SVAB using a prone table between January 2004 and December 2007. SVAB was performed for 190 lesions and USVAB for 73 lesions. Biopsy results were correlated with surgical pathology or followed up for at least 12 months. The diagnostic outcomes of SVAB and USVAB to diagnose microcalcifications were compared. Of 263 lesions, 104 (40%) underwent surgery and 159 (60%) were followed up. SVAB and USVAB groups showed similar final categories or the extent of microcalcifications. US visible lesions were 57 (78%) of 73 at USVAB and 14 (10%) of 140 at SVAB. Of 57 US visible lesions at USVAB, 29 (51%) were not found in initial US but were detectable with the help of DM. Specimen radiographs were negative in 2.1% of lesions at SVAB and in 4.1% at USVAB (p=0.4008). The under-estimation rate and false-negative rate were similar in SVAB and USVAB. US with DM facilitates US visibility of microcalcifications. USVAB with DM can produce acceptable biopsy results, as can SVAB, to diagnose breast microcalcifications in patients with thin breasts.

Effect of humic acid on ciprofloxacin removal by magnetic multifunctional resins

PubMed Central

Wang, Wei; Cheng, Jiade; Jin, Jing; Zhou, Qing; Ma, Yan; Zhao, Qingqing; Li, Aimin

2016-01-01

Background organic matter significantly influences the removal of emerging contaminants in natural water. In this work, the adsorption of ciprofloxacin (CPX) onto a series of magnetic multifunctional resins (GMA10-GMA90) in the presence and absence of humic acid (HA) was conducted to demonstrate the effect of HA. Both hydrophobic and ion exchange interactions contributed to CPX adsorption. Negative charge-assisted hydrogen bonds also participated in the adsorption process, resulting in the high adsorption amount of anionic CPX onto the negatively charged GMA30 under basic solutions. HA could impact CPX adsorption not only as a competitive adsorbate but also as an additional adsorbent. At pH 5.6, the additional adsorption sites provided by adsorbed HA molecules on the resins dominated and thus facilitated the adsorption process. While at pH 10, HA inhibited the adsorption of CPX by directly competing for ion exchange sites and coexisting with CPX in the solution. The ratio of the amount of CPX adsorbed by dissolved HA to that by the resin reached as high as 1.61 for GMA90. The adsorbed HA molecules onto the resins could provide additional adsorption sites for CPX as proven by the enhanced CPX adsorption in HA-preloading systems at pH 5.6. PMID:27464502

Effect of humic acid on ciprofloxacin removal by magnetic multifunctional resins

NASA Astrophysics Data System (ADS)

Wang, Wei; Cheng, Jiade; Jin, Jing; Zhou, Qing; Ma, Yan; Zhao, Qingqing; Li, Aimin

2016-07-01

Background organic matter significantly influences the removal of emerging contaminants in natural water. In this work, the adsorption of ciprofloxacin (CPX) onto a series of magnetic multifunctional resins (GMA10-GMA90) in the presence and absence of humic acid (HA) was conducted to demonstrate the effect of HA. Both hydrophobic and ion exchange interactions contributed to CPX adsorption. Negative charge-assisted hydrogen bonds also participated in the adsorption process, resulting in the high adsorption amount of anionic CPX onto the negatively charged GMA30 under basic solutions. HA could impact CPX adsorption not only as a competitive adsorbate but also as an additional adsorbent. At pH 5.6, the additional adsorption sites provided by adsorbed HA molecules on the resins dominated and thus facilitated the adsorption process. While at pH 10, HA inhibited the adsorption of CPX by directly competing for ion exchange sites and coexisting with CPX in the solution. The ratio of the amount of CPX adsorbed by dissolved HA to that by the resin reached as high as 1.61 for GMA90. The adsorbed HA molecules onto the resins could provide additional adsorption sites for CPX as proven by the enhanced CPX adsorption in HA-preloading systems at pH 5.6.

Oxidation reactions of solid carbonaceous and resinous substances in supercritical water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koda, S.

Recent kinetic studies, particularly those by means of shadowgraphy and X-ray radiography, for supercritical water oxidation of solid carbonaceous and resinous substances have revealed the importance of the O{sub 2} mass transfer process over the intrinsic surface reaction at higher temperatures. The mass transfer processes, internal and external one, should be incorporated in designing SCWO processes for solid substances and related processes such as catalytic SCWO. Some model calculation efforts of late are briefly described. Finally, fundamental information required for future development is itemed.

A vacuum microgripping tool with integrated vibration releasing capability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rong, Weibin; Fan, Zenghua, E-mail: zenghua-fan@163.com; Wang, Lefeng

2014-08-01

Pick-and-place of micro-objects is a basic task in various micromanipulation demands. Reliable releasing of micro-objects is usually disturbed due to strong scale effects. This paper focuses on a vacuum micro-gripper with vibration releasing functionality, which was designed and assembled for reliable micromanipulation tasks. Accordingly, a vibration releasing strategy of implementing a piezoelectric actuator on the vacuum microgripping tool is presented to address the releasing problem. The releasing mechanism was illustrated using a dynamic micro contact model. This model was developed via theoretical analysis, simulations and pull-off force measurement using atomic force microscopy. Micromanipulation experiments were conducted to verify the performancemore » of the vacuum micro-gripper. The results show that, with the assistance of the vibration releasing, the vacuum microgripping tool can achieve reliable release of micro-objects. A releasing location accuracy of 4.5±0.5 μm and a successful releasing rate of around 100% (which is based on 110 trials) were achieved for manipulating polystyrene microspheres with radius of 35–100 μm.« less

Creation of smart composites using an embroidery machine

NASA Astrophysics Data System (ADS)

Torii, Nobuhiro; Oka, Kosuke; Ikeda, Tadashige

2016-04-01

A smart composite with functional fibers and reinforcement fibers optimally placed with an embroidery machine was created. Fiber orientation affects mechanical properties of composite laminates significantly. Accordingly, if the fibers can be placed along a desired curved path, fiber reinforced plastic (FRP) structures can be designed more lightly and more sophisticatedly. To this end a tailored fiber placement method using the embroidery machine have been studied. To add functions to the FRP structures, shape memory alloy (SMA) wires were placed as functional fibers. First, for a certain purpose the paths of the reinforcement fibers and the SMA wires were simultaneously optimized in analysis. Next, the reinforcement fibers and tubes with the SMA wires were placed on fabrics by using the embroidery machine and this fabric was impregnated with resin by using the vacuum assisted resin transfer molding method. This smart composite was activated by applying voltage to the SMA wires. Fundamental properties of the smart composite were examined and the feasibility of the proposed creation method was shown.

Arthroscopically Assisted Latissimus Dorsi Tendon Transfer in Beach-Chair Position

PubMed Central

Jermolajevas, Viktoras; Kordasiewicz, Bartlomiej

2015-01-01

Irreparable rotator cuff tears remain a surgical problem. The open technique of latissimus dorsi (LD) tendon transfer to “replace” the irreparable rotator cuff is already well known. The aim of this article is to present a modified arthroscopically assisted LD tendon transfer technique. This technique was adopted to operate on patients in the beach-chair position with several improvements in tendon harvesting and fixation. It can be divided into 6 steps, and only 1 step—LD muscle and tendon release—is performed open. The advantages of the arthroscopic procedure are sparing of the deltoid muscle, the possibility of repairing the subscapularis tendon, and the ability to visualize structures at risk while performing tendon harvesting (radial nerve) and passing into the subacromial space (axillary nerve). It is performed in a similar manner to standard rotator cuff surgery—the beach-chair position does not need any modification, and no sophisticated equipment for either the open or arthroscopic part of the procedure is necessary. Nevertheless, this is a challenging procedure and should only be attempted after training, as well as extensive practice. PMID:26759777

21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION...,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The resins identified in paragraph (a) of... condensation of xylene-formaldehyde resin and 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins, to...

Design of the ZTH vacuum liner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prince, P.P.; Dike, R.S.

1987-01-01

The current status of the ZTH vacuum liner design is covered by this report. ZTH will be the first experiment to be installed in the CPRF (Confinement Physics Research Facility) at the Los Alamos National Laboratory and is scheduled to be operational at the rated current of 4 MA in 1992. The vacuum vessel has a 2.4 m major radius and a 40 cm minor radius. Operating parameters which drive the vacuum vessel mechanical design include a 300 C bakeout temperature, an armour support system capable of withstanding 25 kV, a high toroidal resistance, 1250 kPa magnetic loading, a 10more » minute cycle time, and high positional accuracy with respect to the conducting shell. The vacuum vessel design features which satisfy the operating parameters are defined. The liner is constructed of Inconel 625 and has a geometry which alternates sections of thin walled bellows with rigid ribs. These composite sections span between pairs of the 16 diagnostic stations to complete the torus. The thin bellows sections maximize the liner toroidal resistance and the ribs provide support and positional accuracy for the armour in relation to the conducting shell. Heat transfer from the vessel is controlled by a blanket wrap of ceramic fiber insulation and the heat flux is dissipated to a water cooling jacket in the conducting shell.« less

Correlations of norbornenyl crosslinked polyimide resin structures with resin thermo-oxidative stability, resin glass transition temperature and composite initial mechanical properties

NASA Technical Reports Server (NTRS)

Alston, William B.

1988-01-01

PMR (polymerization of monomeric reactants) methodology was used to prepare 70 different polyimide oligomeric resins and 30 different unidirectional graphite fiber/polyimide composites. Monomeric composition as well as chain length between sites of crosslinks were varied to examine their effects on resin thermo-oxidative stability and glass transition temperature (Tg) of the cured/postcured resins. A linear correlation of decreasing 316 C resin weight loss/surface area versus (1) decreasing aliphatic content, or (2) increasing benzylic/aliphatic content stoichiometry ratio over a wide range of resin compositions was observed. An almost linear correlation of Tg versus molecular distance between the crosslinks was also observed. An attempt was made to correlate Tg with initial composite mechanical properties (flexural strength and interlaminar shear strength). However, the scatter in mechanical strength data prevented obtaining a clear correlation. Instead, only a range of composite mechanical properties was obtained at 25, 288, and 316 C. Perhaps more importantly, what did become apparent during the correlation study was (1) the PMR methodology could be used to prepare composites from resins containing a wide variety of monomer modifications, (2) that these composites almost invariably provided satisfactory initial mechanical properties as long as the resins formulated exhibited satisfactory processing flow, and (3) that PMR resins exhibited predictable rates of 316 C weight loss/surface area based on their benzylic/aliphatic stoichiometery ratio.

Chemical changes exhibited by latent fingerprints after exposure to vacuum conditions.

PubMed

Bright, Nicholas J; Willson, Terry R; Driscoll, Daniel J; Reddy, Subrayal M; Webb, Roger P; Bleay, Stephen; Ward, Neil I; Kirkby, Karen J; Bailey, Melanie J

2013-07-10

The effect of vacuum exposure on latent fingerprint chemistry has been evaluated. Fingerprints were analysed using a quartz crystal microbalance to measure changes in mass, gas chromatography mass spectrometry to measure changes in lipid composition and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine changes in the content of water, fatty acids and their esters after exposure to vacuum. The results are compared with samples aged under ambient conditions. It was found that fingerprints lose around 26% of their mass when exposed to vacuum conditions, equivalent to around 5 weeks ageing under ambient conditions. Further exposure to vacuum causes a significant reduction in the lipid composition of a fingerprint, in particular with the loss of tetradecanoic and pentadecanoic acid, that was not observed in ambient aged samples. There are therefore implications for sequence in which fingerprint development procedures (for example vacuum metal deposition) are carried out, as well as the use of vacuum based methods such as secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption ionisation (MALDI) in the study of fingerprint chemistry. Copyright © 2013. Published by Elsevier Ireland Ltd.

EVALUATION OF A VACUUM DISTILLER FOR PERFORMING METHOD 8261 ANALYSES

EPA Science Inventory

Vacuum distillation uses a specialized apparatus. This apparatus has been developed and patented by the EPA. Through the Federal Technology Transfer Act this invention has been made available for commercialization. Available vendors for this instrumentation are being evaluated. ...

Initial Experience with a Wireless Ultrasound-Guided Vacuum-Assisted Breast Biopsy Device

PubMed Central

Choi, E-Ryung; Han, Boo-Kyung; Ko, Eun Sook; Ko, Eun Young; Choi, Ji Soo; Cho, Eun Yoon; Nam, Seok Jin

2015-01-01

Objective To determine the imaging characteristic of frequent target lesions of wireless ultrasound (US)-guided, vacuum-assisted breast biopsy (Wi-UVAB) and to evaluate diagnostic yield, accuracy and complication of the device in indeterminate breast lesions. Materials and Methods From March 2013 to October 2014, 114 women (age range, 29–76 years; mean age, 50.0 years) underwent Wi-UVAB using a 13-gauge needle (Mammotome Elite®; Devicor Medical Products, Cincinnati, OH, USA). In 103 lesions of 96 women with surgical (n = 81) or follow-up (n = 22) data, complications, biopsy procedure, imaging findings of biopsy targets and histologic results were reviewed. Results Mean number of biopsy cores was 10 (range 4–25). Nine patients developed moderate bleeding. All lesions were suspicious on US, and included non-mass lesions (67.0%) and mass lesions (33.0%). Visible calcifications on US were evident in 57.3% of the target lesions. Most of the lesions (93.2%) were nonpalpable. Sixty-six (64.1%) were malignant [ductal carcinoma in situ (DCIS) rate, 61%] and 12 were high-risk lesions (11.7%). Histologic underestimation was identified in 11 of 40 (27.5%). DCIS cases and in 3 of 9 (33.3%) high-risk lesions necessitating surgery. There was no false-negative case. Conclusion Wi-UVAB is very handy and advantageous for US-unapparent non-mass lesions to diagnose DCIS, especially for calcification cases. Histologic underestimation is unavoidable; still, Wi-UVAB is safe and accurate to diagnose a malignancy. PMID:26630136

Graphite fiber reinforced thermoplastic resins

NASA Technical Reports Server (NTRS)

Novak, R. C.

1975-01-01

Mechanical properties of neat resin samples and graphite fiber reinforced samples of thermoplastic resins were characterized with particular emphasis directed to the effects of environmental exposure (humidity, temperature and ultraviolet radiation). Tensile, flexural, interlaminar shear, creep and impact strengths were measured for polysulfone, polyarylsulfone and a state-of-the-art epoxy resin samples. In general, the thermoplastic resins exhibited environmental degradation resistance equal to or superior to the reference epoxy resin. Demonstration of the utility and quality of a graphite/thermoplastic resin system was accomplished by successfully thermoforming a simulated compressor blade and a fan exit guide vane.

An infiltration/cure model for manufacture of fabric composites by the resin infusion process

NASA Technical Reports Server (NTRS)

Weideman, Mark H.; Loos, Alfred C.; Dexter, H. Benson; Hasko, Gregory H.

1992-01-01

A 1-D infiltration/cure model was developed to simulate fabrication of advanced textile composites by the resin film infusion process. The simulation model relates the applied temperature and pressure processing cycles, along with the experimentally measured compaction and permeability characteristics of the fabric preforms, to the temperature distribution, the resin degree of cure and viscosity, and the infiltration flow front position as a function of time. The model also predicts the final panel thickness, fiber volume fraction, and resin mass for full saturation as a function of compaction pressure. Composite panels were fabricated using the RTM (Resin Transfer Molding) film infusion technique from knitted, knitted/stitched, and 2-D woven carbon preforms and Hercules 3501-6 resin. Fabric composites were fabricated at different compaction pressures and temperature cycles to determine the effects of the processing on the properties. The composites were C-scanned and micrographed to determine the quality of each panel. Advanced cure cycles, developed from the RTM simulation model, were used to reduce the total cure cycle times by a factor of 3 and the total infiltration times by a factor of 2.

Atmospheres and spectra of strongly magnetized neutron stars - II. The effect of vacuum polarization

NASA Astrophysics Data System (ADS)

Ho, Wynn C. G.; Lai, Dong

2003-01-01

We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B= 1014-1015 G, as appropriate for magnetars. Vacuum polarization modifies the dielectric property of the medium and gives rise to a resonance feature in the opacity; this feature is narrow and occurs at a photon energy that depends on the plasma density. Vacuum polarization can also induce resonant conversion of photon modes via a mechanism analogous to the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism for neutrino oscillation. We construct atmosphere models in radiative equilibrium with an effective temperature of a few ×106 K by solving the full radiative transfer equations for both polarization modes in a fully ionized hydrogen plasma. We discuss the subtleties in treating the vacuum polarization effects in the atmosphere models and present approximate solutions to the radiative transfer problem which bracket the true answer. We show from both analytic considerations and numerical calculations that vacuum polarization produces a broad depression in the X-ray flux at high energies (a few keV <~E<~ a few tens of keV) as compared to models without vacuum polarization; this arises from the density dependence of the vacuum resonance feature and the large density gradient present in the atmosphere. Thus the vacuum polarization effect softens the high-energy tail of the thermal spectrum, although the atmospheric emission is still harder than the blackbody spectrum because of the non-grey opacities. We also show that the depression of continuum flux strongly suppresses the equivalent width of the ion cyclotron line and therefore makes the line more difficult to observe.

Optical and color stabilities of paint-on resins for shade modification of restorative resins.

PubMed

Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Ban, Seiji; Homma, Tetsuya; Takahashi, Hideo

2004-06-01

The purpose of this study was to examine the optical and color stabilities of the paint-on resin used for shade modification of restorative resins. Three shades of paint-on resin and two crown and bridge resins were used. The light transmittance characteristics of the materials during accelerated aging tests such as water immersion, toothbrush abrasion, ultraviolet (UV) light irradiation, and staining tests were measured. Discolorations of materials resulting from tests were also determined. There were no significant effects of water immersion, toothbrush abrasion and UV light irradiation on the light transmittance and visible color change of paint-on resins, whereas the staining tests significantly decreased the light transmittance and increased color change of the translucent shades of materials. Our results indicate that the paint-on resins exhibit stable optical properties and color appearance, which are at least as good as the crown and bridge resins.

Oligonucleotide assisted light-emitting Alq3 microrods: energy transfer effect with fluorescent dyes.

PubMed

Cui, Chunzhi; Park, Dong Hyuk; Kim, Jeongyong; Joo, Jinsoo; Ahn, Dong June

2013-06-14

Oligonucleotide assisted tri(8-hydroxyquinoline) aluminium (Alq3) microrods were prepared for the first time. When hybridized with oligonucleotide labeled by Cy3 fluorescent dye, a significant photoluminescence variation of the Alq3 microrods was observed due to Förster resonance energy transfer, unlike when Cy5-oligonucleotide was used. Versatile nucleotide manipulation would open up wider applications of Alq3-based materials, based on this fundamental observation.

Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface.

PubMed

Zheng, Qijing; Saidi, Wissam A; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V; Petek, Hrvoje; Zhao, Jin

2017-10-11

The van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary to general expectation, efficient electron-hole separation can occur in vertically stacked transition-metal dichalcogenide heterostructure bilayers through ultrafast charge transfer between the neighboring layers despite their weak vdW bonding. In this report, we show by ab initio nonadiabatic molecular dynamics calculations, that instead of direct tunneling, the ultrafast interlayer hole transfer is strongly promoted by an adiabatic mechanism through phonon excitation occurring on 20 fs, which is in good agreement with the experiment. The atomic level picture of the phonon-assisted ultrafast mechanism revealed in our study is valuable both for the fundamental understanding of ultrafast charge carrier dynamics at vdW heterointerfaces as well as for the design of novel quasi-2D devices for optoelectronic and photovoltaic applications.

3D-WOVEN FIBER-REINFORCED COMPOSITE FOR CAD/CAM DENTAL APPLICATION

PubMed Central

Petersen, Richard; Liu, Perng-Ru

2016-01-01

Three-dimensional (3D)-woven noncrimp fiber-reinforced composite (FRC) was tested for mechanical properties in the two principal directions of the main XY plane and compared to different Computer-Aided-Design/Computer-Aided-Machining (CAD/CAM) Dental Materials. The Dental Materials included ceramic with Vitablock Mark II®, ProCAD®, InCeram® Spinel, InCeram® Alumina and InCeram® Zirconia in addition to a resin-based 3M Corp. Paradigm® particulate-filled composite. Alternate material controls included Coors 300 Alumina Ceramic and a tungsten carbide 22% cobalt cermet. The 3D-woven FRC was vacuum assisted resin transfer molding processed as a one-depth-thickness ~19-mm preform with a vinyl-ester resin and cut into blocks similar to the commercial CAD/CAM Dental Materials. Mechanical test samples prepared for a flexural three-point span length of 10.0 mm were sectioned for minimum-depth cuts to compare machinability and fracture resistance between groups. 3D-woven FRC improved mechanical properties with significant statistical differences over all CAD/CAM Dental Materials and Coors Alumina Ceramic for flexural strength (p<0.001), resilience (p<0.05), work of fracture (p<0.001), strain energy release (p<0.05), critical stress intensity factor (p<0.001) and strain (p<0.001). PMID:27642198

3D-WOVEN FIBER-REINFORCED COMPOSITE FOR CAD/CAM DENTAL APPLICATION.

PubMed

Petersen, Richard; Liu, Perng-Ru

2016-05-01

Three-dimensional (3D)-woven noncrimp fiber-reinforced composite (FRC) was tested for mechanical properties in the two principal directions of the main XY plane and compared to different Computer-Aided-Design/Computer-Aided-Machining (CAD/CAM) Dental Materials. The Dental Materials included ceramic with Vitablock Mark II®, ProCAD®, InCeram® Spinel, InCeram® Alumina and InCeram® Zirconia in addition to a resin-based 3M Corp. Paradigm® particulate-filled composite. Alternate material controls included Coors 300 Alumina Ceramic and a tungsten carbide 22% cobalt cermet. The 3D-woven FRC was vacuum assisted resin transfer molding processed as a one-depth-thickness ~19-mm preform with a vinyl-ester resin and cut into blocks similar to the commercial CAD/CAM Dental Materials. Mechanical test samples prepared for a flexural three-point span length of 10.0 mm were sectioned for minimum-depth cuts to compare machinability and fracture resistance between groups. 3D-woven FRC improved mechanical properties with significant statistical differences over all CAD/CAM Dental Materials and Coors Alumina Ceramic for flexural strength (p<0.001), resilience (p<0.05), work of fracture (p<0.001), strain energy release (p<0.05), critical stress intensity factor (p<0.001) and strain (p<0.001).

Accelerator Vacuum Protection System

NASA Astrophysics Data System (ADS)

Barua, Pradip; Kothari, Ashok; Archunan, M.; Joshi, Rajan

2012-11-01

A new and elaborate automatic vacuum protection system using fast acting valve has been installed to avoid accidental venting of accelerator from experimental chamber side. To cover all the beam lines and to reduce the system cost, it has been installed at a common point from where all the seven beam lines originate. The signals are obtained by placing fast response pressure sensing gauges (HV SENSOR) near all the experimental stations. The closing time of the fast valve is 10 milli-second. The fast closing system protects only one vacuum line at a time. At IUAC, we have seven beam lines so one sensor was placed in each of the beam lines near experimental chamber and a multiplexer was incorporated into the fast closing system. At the time of experiment, the sensor of the active beam line is selected through the multiplexer and the Fast closing valve is interlocked with the selected sensor. As soon as the pressure sensor senses the pressure rise beyond a selected pressure, the signal is transferred and the fast valve closes within 10 to 12 millisecond.

Tooth brush abrasion of paint-on resins for shade modification of crown and bridge resins.

PubMed

Fujii, Koichi; Ban, Seiji; McCabe, John F

2003-09-01

The purpose of this study was to evaluate the surface roughness and resistance to toothbrush abrasion of three experimental paint-on composite resins developed for the shade modification of crown and bridge resins. The paint-on resins had less filler volume fraction than restorative composites or the crown and bridge resins and consequently were of low viscosity. The maximum surface roughness (Rmax) and the maximum depth loss by abrasion for the paint-on resins following 40,000 cycles of brushing ranged from 2.45 to 4.07 microm and 8.63 to 13.67 microm, respectively. Rmax values were 37.7-67.5% lower than that for the crown and bridge resin subjected to the same test. Wear depth was 19.9-49.4% lower than for the crown and bridge resin. These results suggest that the paint-on resins are expected to have adequate resistance to toothbrush abrasion and may therefore be suitable for clinical use.

Polyester Resin Hazards

PubMed Central

Bourne, L. B.; Milner, F. J. M.

1963-01-01

Polyester resins are being increasingly used in industry. These resins require the addition of catalysts and accelerators. The handling of polyester resin system materials may give rise to skin irritations, allergic reactions, and burns. The burns are probably due to styrene and organic peroxides. Atmospheric pollution from styrene and explosion and fire risks from organic peroxides must be prevented. Where dimethylaniline is used scrupulous cleanliness and no-touch technique must be enforced. Handling precautions are suggested. Images PMID:14014495

Materials Characterisation and Analysis for Flow Simulation of Liquid Resin Infusion

NASA Astrophysics Data System (ADS)

Sirtautas, J.; Pickett, A. K.; George, A.

2015-06-01

Liquid Resin Infusion (LRI) processes including VARI and VARTM have received increasing attention in recent years, particularly for infusion of large parts, or for low volume production. This method avoids the need for costly matched metal tooling as used in Resin Transfer Moulding (RTM) and can provide fast infusion if used in combination with flow media. Full material characterisation for LRI analysis requires models for three dimensional fabric permeability as a function of fibre volume content, fabric through-thickness compliance as a function of resin pressure, flow media permeability and resin viscosity. The characterisation of fabric relaxation during infusion is usually determined from cyclic compaction tests on saturated fabrics. This work presents an alternative method to determine the compressibility by using LRI flow simulation and fitting a model to experimental thickness measurements during LRI. The flow media is usually assumed to have isotropic permeability, but this work shows greater simulation accuracy from combining the flow media with separation plies as a combined orthotropic material. The permeability of this combined media can also be determined by fitting the model with simulation to LRI flow measurements. The constitutive models and the finite element solution were validated by simulation of the infusion of a complex aerospace demonstrator part.

Molecular Weight Cut-Off and Structural Analysis of Vacuum-Assisted Titania Membranes for Water Processing

PubMed Central

Abd Jalil, Siti Nurehan; Wang, David K.; Yacou, Christelle; Motuzas, Julius; Smart, Simon; Diniz da Costa, João C.

2016-01-01

This work investigates the structural formation and analyses of titania membranes (TM) prepared using different vacuum exposure times for molecular weight (MW) cut-off performance and oil/water separation. Titania membranes were synthesized via a sol-gel method and coated on macroporous alumina tubes followed by exposure to a vacuum between 30 and 1200 s and then calcined at 400 °C. X-ray diffraction and nitrogen adsorption analyses showed that the crystallite size and particle size of titania increased as a function of vacuum time. All the TM membranes were mesoporous with an average pore diameter of ~3.6 nm with an anatase crystal morphology. Water, glucose, sucrose, and polyvinylpyrrolidone with 40 and 360 kDa (PVP-40 kDa and PVP-360 kDa) were used as feed solutions for MW cut-off and hexadecane solution for oil filtration investigation. The TM membranes were not able to separate glucose and sucrose, thus indicating the membrane pore sizes are larger than the kinetic diameter of sucrose of 0.9 nm, irrespective of vacuum exposure time. They also showed only moderate rejection (20%) of the smaller PVP-40 kDa, however, all the membranes were able to obtain an excellent rejection of near 100% for the larger PVP-360 kDa molecule. Furthermore, the TM membranes were tested for the separation of oil emulsions with a high concentration of oil (3000 ppm), reaching high oil rejections of more than 90% of oil. In general, the water fluxes increased with the vacuum exposure time indicating a pore structural tailoring effect. It is therefore proposed that a mechanism of pore size tailoring was formed by an interconnected network of Ti–O–Ti nanoparticles with inter-particle voids, which increased as TiO2 nanoparticle size increased as a function of vacuum exposure time, and thus reduced the water transport resistance through the TM membranes. PMID:28774057

Thermal cycling effects on adhesion of resin-bovine enamel junction among different composite resins.

PubMed

Chen, Wen-Cheng; Ko, Chia-Ling; Wu, Hui-Yu; Lai, Pei-Ling; Shih, Chi-Jen

2014-10-01

Thermal cycling is used to mimic the changes in oral cavity temperature experienced by composite resins when used clinically. The purpose of this study is to assess the thermal cycling effects of in-house produced composite resin on bonding strength. The dicalcium phosphate anhydrous filler surfaces are modified using nanocrystals and silanization (w/NP/Si). The resin is compared with commercially available composite resins Filtek Z250, Z350, and glass ionomer restorative material GIC Fuji-II LC (control). Different composite resins were filled into the dental enamel of bovine teeth. The bond force and resin-enamel junction graphical structures of the samples were determined after thermal cycling between 5 and 55°C in deionized water for 600 cycles. After thermal cycling, the w/NP/Si 30wt%, 50wt% and Filtek Z250, Z350 groups showed higher shear forces than glass ionomer GIC, and w/NP/Si 50wt% had the highest shear force. Through SEM observations, more of the fillings with w/NP/Si 30wt% and w/NP/Si 50wt% groups flowed into the enamel tubule, forming closed tubules with the composite resins. The push-out force is proportional to the resin flow depth and uniformity. The push-out tubule pore and resin shear pattern is the most uniform and consistent in the w/NP/Si 50wt% group. Accordingly, this developed composite resin maintains great mechanical properties after thermal cycling. Thus, it has the potential to be used in a clinical setting when restoring non-carious cervical lesions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Indian Vacuum Society: The Indian Vacuum Society

NASA Astrophysics Data System (ADS)

Saha, T. K.

2008-03-01

The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of

Vacuum-assisted decellularization: an accelerated protocol to generate tissue-engineered human tracheal scaffolds.

PubMed

Butler, Colin R; Hynds, Robert E; Crowley, Claire; Gowers, Kate H C; Partington, Leanne; Hamilton, Nicholas J; Carvalho, Carla; Platé, Manuela; Samuel, Edward R; Burns, Alan J; Urbani, Luca; Birchall, Martin A; Lowdell, Mark W; De Coppi, Paolo; Janes, Sam M

2017-04-01

Patients with large tracheal lesions unsuitable for conventional endoscopic or open operations may require a tracheal replacement but there is no present consensus of how this may be achieved. Tissue engineering using decellularized or synthetic tracheal scaffolds offers a new avenue for airway reconstruction. Decellularized human donor tracheal scaffolds have been applied in compassionate-use clinical cases but naturally derived extracellular matrix (ECM) scaffolds demand lengthy preparation times. Here, we compare a clinically applied detergent-enzymatic method (DEM) with an accelerated vacuum-assisted decellularization (VAD) protocol. We examined the histological appearance, DNA content and extracellular matrix composition of human donor tracheae decellularized using these techniques. Further, we performed scanning electron microscopy (SEM) and biomechanical testing to analyze decellularization performance. To assess the biocompatibility of scaffolds generated using VAD, we seeded scaffolds with primary human airway epithelial cells in vitro and performed in vivo chick chorioallantoic membrane (CAM) and subcutaneous implantation assays. Both DEM and VAD protocols produced well-decellularized tracheal scaffolds with no adverse mechanical effects and scaffolds retained the capacity for in vitro and in vivo cellular integration. We conclude that the substantial reduction in time required to produce scaffolds using VAD compared to DEM (approximately 9 days vs. 3-8 weeks) does not compromise the quality of human tracheal scaffold generated. These findings might inform clinical decellularization techniques as VAD offers accelerated scaffold production and reduces the associated costs. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Thermal conductivity of aerogel blanket insulation under cryogenic-vacuum conditions in different gas environments

NASA Astrophysics Data System (ADS)

E Fesmire, J.; Ancipink, J. B.; Swanger, A. M.; White, S.; Yarbrough, D.

2017-12-01

Thermal conductivity of low-density materials in thermal insulation systems varies dramatically with the environment: cold vacuum pressure, residual gas composition, and boundary temperatures. Using a reference material of aerogel composite blanket (reinforcement fibers surrounded by silica aerogel), an experimental basis for the physical heat transmission model of aerogel composites and other low-density, porous materials is suggested. Cryogenic-vacuum testing between the boundary temperatures of 78 K and 293 K is performed using a one meter cylindrical, absolute heat flow calorimeter with an aerogel blanket specimen exposed to different gas environments of nitrogen, helium, argon, or CO2. Cold vacuum pressures include the full range from 1×10-5 torr to 760 torr. The soft vacuum region, from about 0.1 torr to 10 torr, is complex and difficult to model because all modes of heat transfer - solid conduction, radiation, gas conduction, and convection - are significant contributors to the total heat flow. Therefore, the soft vacuum tests are emphasized for both heat transfer analysis and practical thermal data. Results for the aerogel composite blanket are analyzed and compared to data for its component materials. With the new thermal conductivity data, future applications of aerogel-based insulation systems are also surveyed. These include Mars exploration and surface systems in the 5 torr CO2 environment, field joints for vacuum-jacketed cryogenic piping systems, common bulkhead panels for cryogenic tanks on space launch vehicles, and liquid hydrogen cryofuel systems with helium purged conduits or enclosures.

Imide modified epoxy matrix resins

NASA Technical Reports Server (NTRS)

Scola, D. A.; Pater, R. H.

1981-01-01

High char yield epoxy using novel bisimide amines (BIA's) as curing agents with a state of the art epoxy resin was developed. Stoichiometric quantities of the epoxy resin and the BIA's were studied to determine the cure cycle required for preparation of resin specimens. The bisimide cured epoxies were designated IME's (imide modified epoxy). The physical, thermal and mechanical properties of these novel resins were determined. The levels of moisture absorption exhibited by the bisimide amine cured expoxies (IME's) were considerably lower than the state of the art epoxies. The strain-to-failure of the control resin system was improved 25% by replacement of DDS with 6F-DDS. Each BIA containing resin exhibited twice the char yield of the control resin MY 720/DDS. Graphite fiber reinforced control (C) and IME resins were fabricated and characterized. Two of the composite systems showed superior properties compared to the other Celion 6000/IME composite systems and state of the art graphite epoxy systems. The two systems exhibited excellent wet shear and flexural strengths and moduli at 300 and 350 F.

Experimental Investigation on Mechanical and Thermal Properties of Marble Dust Particulate-Filled Needle-Punched Nonwoven Jute Fiber/Epoxy Composite

NASA Astrophysics Data System (ADS)

Sharma, Ankush; Patnaik, Amar

2018-03-01

The present investigation evaluates the effects of waste marble dust, collected from the marble industries of Rajasthan, India, on the mechanical properties of needle-punched nonwoven jute fiber/epoxy composites. The composites with varying filler contents from 0 wt.% to 30 wt.% marble dust were prepared using vacuum-assisted resin-transfer molding. The influences of the filler material on the void content, tensile strength, flexural strength, interlaminar shear strength (ILSS), and thermal conductivity of the hybrid composites have been analyzed experimentally under the desired optimal conditions. The addition of marble dust up to 30 wt.% increases the flexural strength, ILSS, and thermal conductivity, but decreases the tensile strength. Subsequently, the fractured surfaces of the particulate-filled jute/epoxy composites were analyzed microstructurally by field-emission scanning electron microscopy.

Development of a Modified Vacuum Cleaner for Lunar Surface Systems

NASA Technical Reports Server (NTRS)

Toon, Katherine P.; Lee, Steve A.; Edgerly, Rachel D.

2009-01-01

The National Aeronautics and Space Administration (NASA) mission to expand space exploration will return humans to the Moon with the goal of maintaining a long-term presence. One challenge that NASA will face returning to the Moon is managing the lunar regolith found on the Moon's surface, which will collect on extravehicular activity (EVA) suits and other equipment. Based on the Apollo experience, the issues astronauts encountered with lunar regolith included eye/lung irritation, and various hardware failures (seals, screw threads, electrical connectors and fabric contamination), which were all related to inadequate lunar regolith mitigation. A vacuum cleaner capable of detaching, transferring, and efficiently capturing lunar regolith has been proposed as a method to mitigate the lunar regolith problem in the habitable environment on lunar surface. In order to develop this vacuum, a modified "off-the-shelf" vacuum cleaner has been used to determine detachment efficiency, vacuum requirements, and optimal cleaning techniques to ensure efficient dust removal in habitable lunar surfaces, EVA spacesuits, and air exchange volume. During the initial development of the Lunar Surface System vacuum cleaner, systematic testing was performed with varying flow rates on multiple surfaces (fabrics and metallics), atmospheric (14.7 psia) and reduced pressures (10.2 and 8.3 psia), different vacuum tool attachments, and several vacuum cleaning techniques to determine the performance requirements for the vacuum cleaner. The data recorded during testing was evaluated by calculating percent removal, relative to the retained simulant on the tested surface. In addition, Scanning Electron Microscopy (SEM) imaging was used to determine particle size distribution retained on the surface. The scope of this paper is to explain the initial phase of vacuum cleaner development, including historical Apollo mission data, current state-of-the-art vacuum cleaner technology, and vacuum cleaner

Development of a Modified Vacuum Cleaner for Lunar Surface Systems

NASA Technical Reports Server (NTRS)

Toon, Katherine P.; Lee, Steve A.; Edgerly, Rachel D.

2010-01-01

The National Aeronautics and Space Administration (NASA) mission to expand space exploration will return humans to the Moon with the goal of maintaining a long-term presence. One challenge that NASA will face returning to the Moon is managing the lunar regolith found on the Moon's surface, which will collect on extravehicular activity (EVA) suits and other equipment. Based on the Apollo experience, the issues astronauts encountered with lunar regolith included eye/lung irritation, and various hardware failures (seals, screw threads, electrical connectors and fabric contamination), which were all related to inadequate lunar regolith mitigation. A vacuum cleaner capable of detaching, transferring, and efficiently capturing lunar regolith has been proposed as a method to mitigate the lunar regolith problem in the habitable environment on lunar surface. In order to develop this vacuum, a modified "off-the-shelf' vacuum cleaner will be used to determine detachment efficiency, vacuum requirements, and optimal cleaning techniques to ensure efficient dust removal in habitable lunar surfaces, EVA spacesuits, and air exchange volume. During the initial development of the Lunar Surface System vacuum cleaner, systematic testing was performed with varying flow rates on multiple surfaces (fabrics and metallics), atmospheric (14.7 psia) and reduced pressures (10.2 and 8.3 psia), different vacuum tool attachments, and several vacuum cleaning techniques in order to determine the performance requirements for the vacuum cleaner. The data recorded during testing was evaluated by calculating particulate removal, relative to the retained simulant on the tested surface. In addition, optical microscopy was used to determine particle size distribution retained on the surface. The scope of this paper is to explain the initial phase of vacuum cleaner development, including historical Apollo mission data, current state-of-the-art vacuum cleaner technology, and vacuum cleaner testing that has

Influence of vascular network design on gas transfer in lung assist device technology.

PubMed

Bassett, Erik K; Hoganson, David M; Lo, Justin H; Penson, Elliot J N; Vacanti, Joseph P

2011-01-01

Blood oxygenators are vital for the critically ill, but their use is limited to the hospital setting. A portable blood oxygenator or a lung assist device for ambulatory or long-term use would greatly benefit patients with chronic lung disease. In this work, a biomimetic blood oxygenator system was developed which consisted of a microfluidic vascular network covered by a gas permeable silicone membrane. This system was used to determine the influence of key microfluidic parameters-channel size, oxygen exposure length, and blood shear rate-on blood oxygenation and carbon dioxide removal. Total gas transfer increased linearly with flow rate, independent of channel size and oxygen exposure length. On average, CO(2) transfer was 4.3 times higher than oxygen transfer. Blood oxygen saturation was also found to depend on the flow rate per channel but in an inverse manner; oxygenation decreased and approached an asymptote as the flow rate per channel increased. These relationships can be used to optimize future biomimetic vascular networks for specific lung applications: gas transfer for carbon dioxide removal in patients with chronic obstructive pulmonary disease or oxygenation for premature infants requiring complete lung replacement therapy.

RFI and SCRIMP Model Development and Verification

NASA Technical Reports Server (NTRS)

Loos, Alfred C.; Sayre, Jay

2000-01-01

Vacuum-Assisted Resin Transfer Molding (VARTM) processes are becoming promising technologies in the manufacturing of primary composite structures in the aircraft industry as well as infrastructure. A great deal of work still needs to be done on efforts to reduce the costly trial-and-error methods of VARTM processing that are currently in practice today. A computer simulation model of the VARTM process would provide a cost-effective tool in the manufacturing of composites utilizing this technique. Therefore, the objective of this research was to modify an existing three-dimensional, Resin Film Infusion (RFI)/Resin Transfer Molding (RTM) model to include VARTM simulation capabilities and to verify this model with the fabrication of aircraft structural composites. An additional objective was to use the VARTM model as a process analysis tool, where this tool would enable the user to configure the best process for manufacturing quality composites. Experimental verification of the model was performed by processing several flat composite panels. The parameters verified included flow front patterns and infiltration times. The flow front patterns were determined to be qualitatively accurate, while the simulated infiltration times over predicted experimental times by 8 to 10%. Capillary and gravitational forces were incorporated into the existing RFI/RTM model in order to simulate VARTM processing physics more accurately. The theoretical capillary pressure showed the capability to reduce the simulated infiltration times by as great as 6%. The gravity, on the other hand, was found to be negligible for all cases. Finally, the VARTM model was used as a process analysis tool. This enabled the user to determine such important process constraints as the location and type of injection ports and the permeability and location of the high-permeable media. A process for a three-stiffener composite panel was proposed. This configuration evolved from the variation of the process

Acetylene terminated matrix resins

NASA Technical Reports Server (NTRS)

Goldfarb, I. J.; Lee, Y. C.; Arnold, F. E.; Helminiak, T. E.

1985-01-01

The synthesis of resins with terminal acetylene groups has provided a promising technology to yield high performance structural materials. Because these resins cure through an addition reaction, no volatile by-products are produced during the processing. The cured products have high thermal stability and good properties retention after exposure to humidity. Resins with a wide variety of different chemical structures between the terminal acetylene groups are synthesized and their mechanical properties studied. The ability of the acetylene cured polymers to give good mechanical properties is demonstrated by the resins with quinoxaline structures. Processibility of these resins can be manipulated by varying the chain length between the acetylene groups or by blending in different amounts of reactive deluents. Processing conditions similar to the state-of-the-art epoxy can be attained by using backbone structures like ether-sulfone or bis-phenol-A. The wide range of mechanical properties and processing conditions attainable by this class of resins should allow them to be used in a wide variety of applications.

Environment-assisted Quantum Critical Effect for Excitation Energy Transfer in a LH2-type Trimer

NASA Astrophysics Data System (ADS)

Xu, Lan; Xu, Bo

2015-10-01

In this article, we are investigating excitation energy transfer (EET) in a basic unit cell of light-harvesting complex II (LH2), named a LH2-type trimer. Calculation of energy transfer efficiency (ETE) in the framework of non-Markovian environment is also implemented. With these achievements, we theoretically predict the environment-assisted quantum critical effect, where ETE exhibits a sudden change at the critical point of quantum phase transition (QPT) for the LH2-type trimer. It is found that highly efficient EET with nearly unit efficiency may occur in the vicinity of the critical point of QPT.

Effects of quadratic coupling and squeezed vacuum injection in an optomechanical cavity assisted with a Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Dalafi, A.; Naderi, M. H.; Motazedifard, Ali

2018-04-01

We investigate theoretically a hybrid system consisting of a Bose-Einstein condensate (BEC) trapped inside a laser-driven membrane-in-the-middle optomechanical cavity assisted with squeezed vacuum injection whose moving membrane interacts both linearly and quadratically with the radiation pressure of the cavity. It is shown that such a hybrid system is very suitable for generating strong quadrature squeezing in the mechanical mode of the membrane and the Bogoliubov mode of the BEC in the unresolved sideband regime. More interestingly, by choosing a suitable sign for the quadratic optomechanical coupling (QOC), one can achieve a very high degree of squeezing in the mechanical mode and a strong entanglement between the mechanical and atomic modes without the necessity of using squeezed light injection. Furthermore, the QOC changes the effective oscillation frequencies of both the mechanical and the atomic modes and affects their relaxation times. It can also make the system switch from optical bistability to tristability.

21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

Code of Federal Regulations, 2010 CFR

2010-04-01

...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant substances...

21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

Code of Federal Regulations, 2011 CFR

2011-04-01

...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant substances...

21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

Code of Federal Regulations, 2012 CFR

2012-04-01

...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant substances...

21 CFR 175.380 - Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins.

Code of Federal Regulations, 2013 CFR

2013-04-01

...-isopropylidenediphenol-epichlorohydrin epoxy resins. 175.380 Section 175.380 Food and Drugs FOOD AND DRUG ADMINISTRATION... Xylene-formaldehyde resins condensed with 4,4′-isopropylidenediphenol-epichlorohydrin epoxy resins. The...′-isopropylidenediphenol-epichlorohydrin epoxy resins, to which may have been added certain optional adjuvant substances...

Method for removing contaminants from plastic resin

DOEpatents

Bohnert, George W [Harrisonville, MO; Hand, Thomas E [Lee's Summit, MO; DeLaurentiis, Gary M [Jamestown, CA

2008-12-09

A resin recycling method that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The method includes receiving the resin in container form. The containers are then ground into resin particles. The particles are exposed to a solvent, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. After separating the particles and the resin, a solvent removing agent is used to remove any residual solvent remaining on the resin particles after separation.

Numerical Study on Radiation Effects to Evaporator in Natural Vacuum Solar Desalination System

NASA Astrophysics Data System (ADS)

Siregar, R. E. T.; Ronowikarto, A. D.; Setyawan, E. Y.; Ambarita, H.

2018-01-01

The need for clean water is increasing day by day due to the increasing factor of living standard of mankind, hence designed natural vacuum solar desalination. The natural vacuum Solar desalination is studied experimentally. A small-scale natural vacuum desalination study consists of evaporator and condenser as the main components designed and manufactured. To transfer heat from the solar collector into the evaporator, the fluid transfer system uses a pump powered by a solar cell. Thus, solar collectors are called hybrid solar collectors. The main purpose of this exposure is to know the characteristics of the radiation effects on incoming energy on the evaporator during the process. This system is tested by exposing the unit to the solar radiation in the 4th floor building in Medan. The experiment was conducted from 8.00 to 16.00 local time. The results show that natural vacuum solar desalination with hybrid solar collectors can be operated perfectly. If the received radiation is high, then the incoming energy received by the evaporator will also be high. From measurements with HOBO microstation, obtained the highest radiation 695.6 W/m2, and the calculation result of incoming energy received evaporator obtained highest result 1807.293 W.

Experimental Investigation on Acoustic Control Droplet Transfer in Ultrasonic-Wave-Assisted Gas Metal Arc Welding

NASA Astrophysics Data System (ADS)

Weifeng, Xie; Chenglei, Fan; Chunli, Yang; Sanbao, Lin

2018-02-01

Ultrasonic-wave-assisted gas metal arc welding (U-GMAW) is a new, advanced arc welding method that uses an ultrasonic wave emitted from an ultrasonic radiator above the arc. However, it remains unclear how the ultrasonic wave affects the metal droplet, hindering further application of U-GMAW. In this paper, an improved U-GMAW system was used and its superiority was experimentally demonstrated. Then a series of experiments were designed and performed to study how the ultrasonic wave affects droplet transfer, including droplet size, velocity, and motion trajectory. The behavior of droplet transfer was observed in high-speed images. The droplet transfer is closely related to the distribution of the acoustic field, determined by the ultrasonic current. Moreover, by analyzing the variably accelerated motion of the droplet, the acoustic control of the droplet transfer was intuitively demonstrated. Finally, U-GMAW was successfully used in vertical-up and overhead welding experiments, showing that U-GMAW is promising for use in welding in all positions.

Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility.

PubMed

Shim, Hyun-Sub; Moon, Chang-Ki; Kim, Jihun; Wang, Chun-Kai; Sim, Bomi; Lin, Francis; Wong, Ken-Tsung; Seo, Yongsok; Kim, Jang-Joo

2016-01-20

The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.

Evaluation of fit of cement-retained implant-supported 3-unit structures fabricated with direct metal laser sintering and vacuum casting techniques.

PubMed

Oyagüe, Raquel Castillo; Sánchez-Turrión, Andrés; López-Lozano, José Francisco; Montero, Javier; Albaladejo, Alberto; Suárez-García, María Jesús

2012-07-01

This study evaluated the vertical discrepancy of implant-fixed 3-unit structures. Frameworks were constructed with laser-sintered Co-Cr, and vacuum-cast Co-Cr, Ni-Cr-Ti, and Pd-Au. Samples of each alloy group were randomly luted in standard fashion using resin-modified glass-ionomer, self-adhesive, and acrylic/urethane-based cements (n = 12 each). Discrepancies were SEM analyzed. Three-way ANOVA and Student-Newman-Keuls tests were run (P < 0.05). Laser-sintered structures achieved the best fit per cement tested. Within each alloy group, resin-modified glass-ionomer and acrylic/urethane-based cements produced comparably lower discrepancies than the self-adhesive agent. The abutment position did not yield significant differences. All misfit values could be considered clinically acceptable.

[Learning curve of vacuum extraction in residency: a preliminary study].

PubMed

Velemir, L; Vendittelli, F; Bonnefoy, C; Accoceberry, M; Savary, D; Gallot, D

2009-09-01

The aim of this study was to assess the lurning curve of young residents for vacuum extraction. All vacuum extractions performed in our department by five residents (< or =5th semester) during a study period of nine months were systematically supervised by a senior who fulfilled an assessment questionnaire from which was calculated a score reflecting the quality of the extraction. Fifty-four vacuum extractions were assessed with a mean of 10.8+/-2.9 (range, 10-13) procedures by resident. We compared the group including the six first procedures performed by each resident (group 1, n = 30) with the group including the following procedures (group 2, n = 24). We observed in the group 2 compared to the group 1, a significant improvement of the scores mean (12.3+/-5.4 vs 8.4+/-6.2, p = 0.016) and a significant reduction of the need for manual assistance by the senior (12.5% vs 40%, p = 0.034). We report a method for the learning and assessment of vacuum extraction feasible at "the bed" of the patient. This approach allows to observe a significant progression of the resident for the technique of vacuum extraction on a dozen of procedures.

System for removing contaminants from plastic resin

DOEpatents

Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

2010-11-23

A resin recycling system that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The system includes receiving the resin in container form. A grinder grinds the containers into resin particles. The particles are exposed to a solvent in one or more solvent wash vessels, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. A separator is used to separate the resin particles and the solvent. The resin particles are then placed in solvent removing element where they are exposed to a solvent removing agent which removes any residual solvent remaining on the resin particles after separation.

Comparative tensile strength study of the adhesion improvement of PTFE by UV photon assisted surface processing

NASA Astrophysics Data System (ADS)

Hopp, B.; Geretovszky, Zs.; Bertóti, I.; Boyd, I. W.

2002-01-01

Poly(tetrafluoroethylene) (PTFE) is notable for its non-adhesive and non-reactive properties. A number of technologies can potentially benefit from the application of PTFE, but these characteristics restrict the ability to structuring its surface. In this paper, we present results on two ultraviolet photon assisted treatments of PTFE. The originally poor adhesion was significantly improved by both 172 nm excimer lamp and 193 nm excimer laser assisted surface treatments. While Xe2∗ lamp irradiation, applied in a modest vacuum environment, was sufficient by itself to improve adhesion, the ArF laser process was only effective when the irradiated interface was in contact with 1,2-diaminoethane photoreagent. It was found that the tensile strength of an epoxy resin glued interface created on treated surfaces depended strongly on the applied number of laser pulses and lamp irradiation time. Laser treatment caused fast tensile strength increase during the first 50-500 pulses, while after this it saturates slowly at about 5.5 MPa in the 500-2500 pulse domain. The excimer lamp irradiation resulted in a maximum tensile strength of approximately 10 MPa after 2 min irradiation time which reduced to about 65% of the peak value at longer times.

Cross-reactivity among epoxy acrylates and bisphenol F epoxy resins in patients with bisphenol A epoxy resin sensitivity.

PubMed

Lee, Han N; Pokorny, Christopher D; Law, Sandra; Pratt, Melanie; Sasseville, Denis; Storrs, Frances J

2002-09-01

The study's objective was 2-fold: first, to evaluate the potential cross-reactivity between Bis-A epoxy resins and epoxy acrylates and second, to study the cross reactivity between Bis-A epoxy resins and newer Bis-F epoxy resins in patients with allergic contact dermatitis to epoxy resins and had positive patch test to the standard epoxy resin based on bisphenol A. Forty-one patients were patch tested to 23 chemicals including epoxy acrylates, Bis-A epoxy resins, and Bis-F epoxy resins, as well as reactive diluents and nonbisphenol epoxy resins. Questions concerning exposure to epoxy resins, occupational history, and problems with dental work were completed. All patients included in the study had positive reactions to the standard Bis-A epoxy resin. Twenty percent (8 of 41) of the patients reacted to at least one of the epoxy acrylates; the most common reaction was to Bis-GMA. Five of 8 patients who reacted to the epoxy acrylates had dental work, but only one patient had problems from her dental work. Six of 8 patients (75%) who reacted to epoxy resins and epoxy acrylates did not react to aliphatic acrylates. Thirty-two percent (13 of 41) reacted to tosylamide epoxy resin, and none reacted to triglycidyl isocyanurate resin. In addition, all patients (100%) had positive reactions to at least one of the Bis-F epoxy resins that were tested. Most patients with sensitivity to Bis-A epoxy resins do not cross-react with epoxy acrylates. Patients with positive patch test reactions to epoxy acrylates used in dentistry usually do not have symptoms from their dental work. To our knowledge, this is the largest series of patients with sensitivity to the standard Bis-A epoxy resin that have been patch tested with the more recently introduced Bis-F epoxy resins. There is significant cross-reactivity between Bis-A and Bis-F epoxy resins, which can be explained by their structural similarity. Copyright 2002, Elsevier Science (USA). All rights reserved.

Assessment of cross-reactivity of new less sensitizing epoxy resin monomers in epoxy resin-allergic individuals.

PubMed

Hagvall, Lina; Niklasson, Ida B; Rudbäck, Johanna; O'Boyle, Niamh M; Niklasson, Eva; Luthman, Kristina; Karlberg, Ann-Therese

2016-09-01

Measures to prevent occupational exposure to epoxy resins, including education, medical examination, and voluntary agreements between employers and workers, have not been effective enough to protect against skin sensitization. Therefore, alternatives to the major epoxy resin haptens that have been found to be less sensitizing in the local lymph node assay have been developed. To study the cross-reactivity of two newly designed epoxy resin monomers, with decreased skin-sensitizing potency and good technical properties as compared with diglycidyl ether of bisphenol A (DGEBA), in subjects with known contact allergy to epoxy resin of DGEBA type. Eleven individuals with previous positive patch test reactions to epoxy resin of DGEBA participated in the study. The two alternative epoxy resin monomers were synthesized and patch tested in dilution series in parallel with epoxy resin of DGEBA from the baseline series (containing 92% DGEBA). All participants reacted to epoxy resin of DGEBA on retesting. Three participants reacted to monomer 1. No reactions were seen to monomer 2. The alternative monomers studied showed little or no cross-reactivity with epoxy resin of DGEBA. Decreasing the risk of sensitization by using less sensitizing compounds is important, as contact allergy to epoxy resins is common in spite of thorough preventive measures. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Ultrasonic Spray Drying vs High Vacuum and Microwaves Technology for Blueberries

NASA Astrophysics Data System (ADS)

Candia-Muñoz, N.; Ramirez-Bunster, M.; Vargas-Hernández, Y.; Gaete-Garretón, L.

Interest in high quality foods: good taste and a high content of nutrients with healthy beneficial effects are increasing. Fruits have good properties but, they are lost because the oxidation process, additionally, for different reasons a 40% of harvested fruit are lost. To conserve the fruit properties an ultrasonic assisted spray dryer was developed and tested, comparing its results with microwave-vacuum drying technology. Results did shown taste, color, smell, particle shape and size distribution better than the conventional one. The antioxidants conservation were quite good except in the anthocyanins, in which the microwave and vacuum technology shown best results.

Advanced thermoplastic resins, phase 1

NASA Technical Reports Server (NTRS)

Hendricks, C. L.; Hill, S. G.; Falcone, A.; Gerken, N. T.

1991-01-01

Eight thermoplastic polyimide resin systems were evaluated as composite matrix materials. Two resins were selected for more extensive mechanical testing and both were versions of LaRC-TPI (Langley Research Center - Thermoplastic Polyimide). One resin was made with LaRC-TPI and contained 2 weight percent of a di(amic acid) dopant as a melt flow aid. The second system was a 1:1 slurry of semicrystalline LaRC-TPI powder in a polyimidesulfone resin diglyme solution. The LaRC-TPI powder melts during processing and increases the melt flow of the resin. Testing included dynamic mechanical analysis, tension and compression testing, and compression-after-impact testing. The test results demonstrated that the LaRC-TPI resins have very good properties compared to other thermoplastics, and that they are promising matrix materials for advanced composite structures.

Manufacturing a 9-Meter Thermoplastic Composite Wind Turbine Blade: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, Robynne; Snowberg, David R; Berry, Derek S

Currently, wind turbine blades are manufactured from a combination of glass and/or carbon fiber composite materials with a thermoset resin such as epoxy, which requires energy-intensive and expensive heating processes to cure. Newly developed in-situ polymerizing thermoplastic resin systems for composite wind turbine blades polymerize at room temperature, eliminating the heating process and significantly reducing the blade manufacturing cycle time and embodied energy, which in turn reduces costs. Thermoplastic materials can also be thermally welded, eliminating the need for adhesive bonds between blade components and increasing the overall strength and reliability of the blades. As well, thermoplastic materials enable end-of-lifemore » blade recycling by reheating and decomposing the materials, which is a limitation of existing blade technology. This paper presents a manufacturing demonstration for a 9-m-long thermoplastic composite wind turbine blade. This blade was constructed in the Composites Manufacturing Education and Technology facility at the National Wind Technology Center at the National Renewable Energy Laboratory (NREL) using a vacuum-assisted resin transfer molding process. Johns Manville fiberglass and an Arkema thermoplastic resin called Elium were used. Additional materials included Armacell-recycled polyethylene terephthalate foam from Creative Foam and low-cost carbon- fiber pultruded spar caps (manufactured in collaboration with NREL, Oak Ridge National Laboratory, Huntsman, Strongwell, and Chomarat). This paper highlights the development of the thermoplastic resin formulations, including an additive designed to control the peak exothermic temperatures. Infusion and cure times of less than 3 hours are also demonstrated, highlighting the efficiency and energy savings associated with manufacturing thermoplastic composite blades.« less

Reduction of benzene and naphthalene mass transfer from crude oils by aging-induced interfacial films.

PubMed

Ghoshal, Subhasis; Pasion, Catherine; Alshafie, Mohammed

2004-04-01

Semi-rigid films or skins form at the interface of crude oil and water as a result of the accumulation of asphaltene and resin fractions when the water-immiscible crude oil is contacted with water for a period of time or "aged". The time varying patterns of area-independent mass transfer coefficients of two compounds, benzene and naphthalene, for dissolution from crude oil and gasoline were determined. Aqueous concentrations of the compounds were measured in the eluent from flow-through reactors, where a nondispersed oil phase and constant oil-water interfacial area were maintained. For Brent Blend crude oil and for gasoline amended with asphaltenes and resins, a rapid decrease in both benzene and naphthalene mass transfer coefficients over the first few days of aging was observed. The mass transfer coefficients of the two target solutes were reduced by up to 80% over 35 d although the equilibrium partition coefficients were unchanged. Aging of gasoline, which has negligible amounts of asphaltene and resin, did not result in a change in the solute mass transfer coefficients. The study demonstrates that formation of crude oil-water interfacial films comprised of asphaltenes and resins contribute to time-dependent decreases in rates of release of environmentally relevant solutes from crude oils and may contribute to the persistence of such solutes at crude oil-contaminated sites. It is estimated that the interfacial film has an extremely low film mass transfer coefficient in the range of 10(-6) cm/min.

Thickness dependent charge transfer states and dark carriers density in vacuum deposited small molecule organic photocell

NASA Astrophysics Data System (ADS)

Shekhar, Himanshu; Tzabari, Lior; Solomeshch, Olga; Tessler, Nir

2016-10-01

We have investigated the influence of the active layer thickness on the balance of the internal mechanisms affecting the efficiency of copper phthalocyanine - fullerene (C60) based vacuum deposited bulk heterojunction organic photocell. We fabricated a range of devices for which we varied the thickness of the active layer from 40 to 120 nm and assessed their performance using optical and electrical characterization techniques. As reported previously for phthalocyanine:C60, the performance of the device is highly dependent on the active layer thickness and of all the thicknesses we tried, the 40 nm thin active layer device showed the best solar cell characteristic parameters. Using the transfer matrix based optical model, which includes interference effects, we calculated the optical power absorbed in the active layers for the entire absorption band, and we found that this cannot explain the trend with thickness. Measurement of the cell quantum efficiency as a function of light intensity showed that the relative weight of the device internal processes changes when going from 40 nm to 120 nm thick active layer. Electrical modeling of the device, which takes different internal processes into account, allowed to quantify the changes in the processes affecting the generation - recombination balance. Sub gap external quantum efficiency and morphological analysis of the surface of the films agree with the model's result. We found that as the thickness grows the density of charge transfer states and of dark carriers goes up and the uniformity in the vertical direction is reduced.

In-situ measurement of thermoset resin degree of cure using embedded fiber optic

NASA Astrophysics Data System (ADS)

Breglio, Giovanni; Cusano, Andrea; Cutolo, Antonello; Calabro, Antonio M.; Cantoni, Stefania; Di Vita, Gandolfo; Buonocore, Vincenzo; Giordano, Michele; Nicolais, Luigi, II

1999-12-01

In this work, a fiber optic sensor based on Fresnel principle is presented. It is used to monitor the variations of the refractive index due to the cure process of an epoxy based resin. These materials are widely used in polymer- matrix composites. The process of thermoset matrix based composite involves mass and heat transfer coupled with irreversible chemical reactions inducing physical changes: the transformation of a fluid resin into a rubber and then into a solid glass. To improve the quality and the reliability of these materials key points are the cure monitoring and the optimization of the manufacturing process. To this aim, the fiber optic embedded sensor has been designed, developed and tested. Preliminary results on sensor capability to monitor the cure kinetics are shown. Correlation between the sensor output and conversion advancement has been proposed following the Lorentz-Lorenz law. Isothermal data form the sensor have been compared with calorimetric analysis of an epoxy based resin.

Vacuum mechatronics

NASA Technical Reports Server (NTRS)

Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

1989-01-01

The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

Incombustible resin composition

NASA Technical Reports Server (NTRS)

Akima, T.

1982-01-01

Incombustible resin compositions composed of aromatic compounds were obtained through (1) combustion polymer material and (2) bisphenol A or halogenated bisphenol A and bisphenol A diglycidl ether or halogenated bisphenol A diglycidyl ether. The aromatic compound is an adduct of bifunctional phenols and bifunctional epoxy resins.

Thermal Vacuum Integrated System Test at B-2

NASA Technical Reports Server (NTRS)

Kudlac, Maureen T.; Weaver, Harold F.; Cmar, Mark D.

2012-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Plum Brook Station (PBS) Space Propulsion Research Facility, commonly referred to as B-2, is NASA s third largest thermal vacuum facility. It is the largest designed to store and transfer large quantities of liquid hydrogen and liquid oxygen, and is perfectly suited to support developmental testing of chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing thermal-vacuum simulation services to support testing of large lightweight structures, Cryogenic Fluid Management (CFM) systems, electric propulsion test programs, and other In-Space propulsion programs. A recently completed integrated system test demonstrated the refurbished thermal vacuum capabilities of the facility. The test used the modernized data acquisition and control system to monitor the facility during pump down of the vacuum chamber, operation of the liquid nitrogen heat sink (or cold wall) and the infrared lamp array. A vacuum level of 1.3x10(exp -4)Pa (1x10(exp -6)torr) was achieved. The heat sink provided a uniform temperature environment of approximately 77 K (140deg R) along the entire inner surface of the vacuum chamber. The recently rebuilt and modernized infrared lamp array produced a nominal heat flux of 1.4 kW/sq m at a chamber diameter of 6.7 m (22 ft) and along 11 m (36 ft) of the chamber s cylindrical vertical interior. With the lamp array and heat sink operating simultaneously, the thermal systems produced a heat flux pattern simulating radiation to space on one surface and solar exposure on the other surface. The data acquired matched pretest predictions and demonstrated system functionality.

An Enhanced Vacuum Cure Technique for On-Aircraft Repair of Carbon-Bismaleimide Composites

NASA Astrophysics Data System (ADS)

Rider, Andrew N.; Baker, Alan A.; Wang, Chun H.; Smith, Graeme

2011-06-01

Carbon/bismaleimide (BMI) composite is increasingly employed in critical load carrying aircraft structures designed to operate at temperatures approaching 180°C. The high post-cure temperature (above 220°C) required to fully react the BMI resin, however, renders existing on-aircraft prepreg or wet layup repair methods invalid. This paper presents a new on-aircraft repair technique for carbon/BMI composites. The composite prepregs are first warm-staged to improve the ability to evacuate entrapped air. Then the patch is cured in the scarf cavity using the vacuum bag technique, followed by off-aircraft post-cure. The fully cured patch then can be bonded using a structural adhesive.

Fresh versus frozen embryo transfers in assisted reproduction.

PubMed

Wong, Kai Mee; van Wely, Madelon; Mol, Femke; Repping, Sjoerd; Mastenbroek, Sebastiaan

2017-03-28

In general, in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) implies a single fresh and one or more frozen-thawed embryo transfers. Alternatively, the 'freeze-all' strategy implies transfer of frozen-thawed embryos only, with no fresh embryo transfers. In practice, both strategies can vary technically including differences in freezing techniques and timing of transfer of cryopreservation, that is vitrification versus slow freezing, freezing of two pro-nucleate (2pn) versus cleavage-stage embryos versus blastocysts, and transfer of cleavage-stage embryos versus blastocysts.In the freeze-all strategy, embryo transfers are disengaged from ovarian stimulation in the initial treatment cycle. This could avoid a negative effect of ovarian hyperstimulation on the endometrium and thereby improve embryo implantation. It could also reduce the risk of ovarian hyperstimulation syndrome (OHSS) in the ovarian stimulation cycle by avoiding a pregnancy.We compared the benefits and risks of the two treatment strategies. To evaluate the effectiveness and safety of the freeze-all strategy compared to the conventional IVF/ICSI strategy in women undergoing assisted reproductive technology. We searched the Cochrane Gynaecology and Fertility Group Trials Register, the Cochrane Central Register of Studies (CRSO), MEDLINE, Embase, PsycINFO, CINAHL, and two registers of ongoing trials in November 2016 together with reference checking and contact with study authors and experts in the field to identify additional studies. We included randomised clinical trials comparing a freeze-all strategy with a conventional IVF/ICSI strategy which includes fresh transfer of embryos in women undergoing IVF or ICSI treatment. We used standard methodological procedures recommended by Cochrane. The primary review outcomes were cumulative live birth and OHSS. Secondary outcomes included other adverse effects (miscarriage rate). We included four randomised clinical trials analysing a total

4-META opaque resin--a new resin strongly adhesive to nickel-chromium alloy.

PubMed

Tanaka, T; Nagata, K; Takeyama, M; Atsuta, M; Nakabayashi, N; Masuhara, E

1981-09-01

1) A new adhesive opaque resin containing a reactive monomer, 4-methacryloxy-ethyl trimellitate anhydride (4-META), was prepared, and its application to thermosetting acrylic resin veneer crowns was studied. 2) The 4-META opaque resin was applied to a variety of nickel-chromium dental alloy specimens which had undergone different treatment, and endurance tests were conducted to evaluate the durability of adhesion. 3) Stable adhesion against water penetration was achieved with metal surfaces first etched with HCl and then oxidized with HNO3. A bond strength of 250 kg/cm2 was maintained even after immersion in water at 37 degrees C for 30 wk or at 80 degrees C for ten wk. Furthermore, this value did not decrease even after the specimens were subjected to 500 thermal cycles. 4) The 4-META opaque resin studied can eliminate the necessity for retention devices on metal castings. 5) The smooth 4-META opaque resin should have no adverse effects on gingivae.

Optical properties of paint-on resins for shade modification of crown and bridge resins--light transmittance characteristics--.

PubMed

Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Homma, Tetsuya; Takahashi, Hideo; Ban, Seiji

2003-09-01

The purpose of this study was to examine the light transmittance characteristics of the paint-on resins for shade modification. Three shades of paint-on resin, one crown and bridge resin, and human enamel were used. Specimens with four different thicknesses (75-150 microm) were prepared. The light transmittances including its wavelength distribution and diffusion characteristics were measured. The color values and the color differences among thicknesses of specimens were also determined. The light transmittance values of the paint-on resins ranged from 60.3% to 88.3% at 100 microm thickness, which were lower or nearly equal in comparison with the crown and bridge resin and enamel. Although differences in the wavelength distribution of transmittance among materials were found at lower wavelengths, all materials showed similar diffusion characteristics. The thin layer of paint-on resin effectively changed the color of restorative resin. The paint-on resin may be an effective material for the modification of the color appearance matching required.

Infusion Processing of Phenylethynyl Terminated Imides by High Temperature RTM and VARTM

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Lewis, Todd M.; Cano, Roberto J.; Watson, Kent A.; Isayev, Avraam I.

2011-01-01

Fabrication of composite structures using infusion processes such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting both technologies for the fabrication of high temperature (HT) resistant composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using these high temperature out-of-autoclave processes. In the current study, two PETI resins, LARC(TradeMark) PETI-330 and LARC(TradeMark) PETI-8 have been used to make test specimens using both RTM and VARTM. For aerospace applications, a void fraction of less than 2% is desired. Traditionally, RTM has had the advantage over VARTM for generating composites with low void content. However, the process is limited in terms of size. Work at NASA LaRC has incorporated modifications to the thermal cycle used in laminate fabrication that have reduced the void content significantly (typically 1-3%) using the current HT-VARTM process. For composite fabrication by both RTM and VARTM, the resins were infused into three carbon fiber preforms (T650-35-3k 5HS, IM7-6k 5HS, and IM7-6k Uniweave) at 316 C and 260 C respectively and cured up to 371 C. The details of the RTM processing carried out at the University of Akron are discussed in this work along with a brief description of the HT-VARTM processing carried out at NASA-LaRC. Photomicrographs of the panels were taken and void contents were determined by acid digestion. Mechanical properties (short beam shear, SBS) of the panels fabricated by both infusion processes were determined at room temperature as well as at various elevated temperatures. The results of this work are presented herein.

Natural vacuum electronics

NASA Technical Reports Server (NTRS)

Leggett, Nickolaus

1990-01-01

The ambient natural vacuum of space is proposed as a basis for electron valves. Each valve is an electron controlling structure similiar to a vacuum tube that is operated without a vacuum sustaining envelope. The natural vacuum electron valves discussed offer a viable substitute for solid state devices. The natural vacuum valve is highly resistant to ionizing radiation, system generated electromagnetic pulse, current transients, and direct exposure to space conditions.

Flavin Charge Transfer Transitions Assist DNA Photolyase Electron Transfer

NASA Astrophysics Data System (ADS)

Skourtis, Spiros S.; Prytkova, Tatiana; Beratan, David N.

2007-12-01

This contribution describes molecular dynamics, semi-empirical and ab-initio studies of the primary photo-induced electron transfer reaction in DNA photolyase. DNA photolyases are FADH--containing proteins that repair UV-damaged DNA by photo-induced electron transfer. A DNA photolyase recognizes and binds to cyclobutatne pyrimidine dimer lesions of DNA. The protein repairs a bound lesion by transferring an electron to the lesion from FADH-, upon photo-excitation of FADH- with 350-450 nm light. We compute the lowest singlet excited states of FADH- in DNA photolyase using INDO/S configuration interaction, time-dependent density-functional, and time-dependent Hartree-Fock methods. The calculations identify the lowest singlet excited state of FADH- that is populated after photo-excitation and that acts as the electron donor. For this donor state we compute conformationally-averaged tunneling matrix elements to empty electron-acceptor states of a thymine dimer bound to photolyase. The conformational averaging involves different FADH--thymine dimer confromations obtained from molecular dynamics simulations of the solvated protein with a thymine dimer docked in its active site. The tunneling matrix element computations use INDO/S-level Green's function, energy splitting, and Generalized Mulliken-Hush methods. These calculations indicate that photo-excitation of FADH- causes a π→π* charge-transfer transition that shifts electron density to the side of the flavin isoalloxazine ring that is adjacent to the docked thymine dimer. This shift in electron density enhances the FADH--to-dimer electronic coupling, thus inducing rapid electron transfer.

Capillary-Force-Assisted Clean-Stamp Transfer of Two-Dimensional Materials.

PubMed

Ma, Xuezhi; Liu, Qiushi; Xu, Da; Zhu, Yangzhi; Kim, Sanggon; Cui, Yongtao; Zhong, Lanlan; Liu, Ming

2017-11-08

A simple and clean method of transferring two-dimensional (2D) materials plays a critical role in the fabrication of 2D electronics, particularly the heterostructure devices based on the artificial vertical stacking of various 2D crystals. Currently, clean transfer techniques rely on sacrificial layers or bulky crystal flakes (e.g., hexagonal boron nitride) to pick up the 2D materials. Here, we develop a capillary-force-assisted clean-stamp technique that uses a thin layer of evaporative liquid (e.g., water) as an instant glue to increase the adhesion energy between 2D crystals and polydimethylsiloxane (PDMS) for the pick-up step. After the liquid evaporates, the adhesion energy decreases, and the 2D crystal can be released. The thin liquid layer is condensed to the PDMS surface from its vapor phase, which ensures the low contamination level on the 2D materials and largely remains their chemical and electrical properties. Using this method, we prepared graphene-based transistors with low charge-neutral concentration (3 × 10 10 cm -2 ) and high carrier mobility (up to 48 820 cm 2 V -1 s -1 at room temperature) and heterostructure optoelectronics with high operation speed. Finally, a capillary-force model is developed to explain the experiment.

Action of ionizing radiation on epoxy resins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van de Voorde, M. E.

1970-12-01

The resistance of classical and experimental epoxy resins to irradiation was studied. The resistance to irradiation of epoxy resins of diverse compositions as well as the development of resins having a radioresistance that approaches that of certain ceramics are discussed. Sources of irradiation and the techniques of dosimetry used are described. The structures of certain epoxy resins and of hardeners are given. The preparation of these resins and their physical properties is described. The effects of radiation on epoxy resins, as well as conditions of irradiation, and suggested mechanisms for degradation of the irradiated resins are discussed. The relationship betweenmore » chemical structure of the resins and their physical properties is evaluated. (115 references) (JCB)« less

Curing behavior and reaction kinetics of binder resins for 3D-printing investigated by dielectric analysis (DEA)

NASA Astrophysics Data System (ADS)

Möginger, B.; Kehret, L.; Hausnerova, B.; Steinhaus, J.

2016-05-01

3D-Printing is an efficient method in the field of additive manufacturing. In order to optimize the properties of manufactured parts it is essential to adapt the curing behavior of the resin systems with respect to the requirements. Thus, effects of resin composition, e.g. due to different additives such as thickener and curing agents, on the curing behavior have to be known. As the resin transfers from a liquid to a solid glass the time dependent ion viscosity was measured using DEA with flat IDEX sensors. This allows for a sensitive measurement of resin changes as the ion viscosity changes two to four decades. The investigated resin systems are based on the monomers styrene and HEMA. To account for the effects of copolymerization in the calculation of the reaction kinetics it was assumed that the reaction can be considered as a homo-polymerization having a reaction order n≠1. Then the measured ion viscosity curves are fitted with the solution of the reactions kinetics - the time dependent degree of conversion (DC-function) - for times exceeding the initiation phase representing the primary curing. The measured ion viscosity curves can nicely be fitted with the DC-function and the determined fit parameters distinguish distinctly between the investigated resin compositions.

21 CFR 177.2510 - Polyvinylidene fluoride resins.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinylidene fluoride resins. 177.2510 Section... Repeated Use § 177.2510 Polyvinylidene fluoride resins. Polyvinylidene fluoride resins may be safely used... fluoride resins consist of basic resins produced by the polymerization of vinylidene fluoride. (b) The...

Using vacuum pyrolysis and mechanical processing for recycling waste printed circuit boards.

PubMed

Long, Laishou; Sun, Shuiyu; Zhong, Sheng; Dai, Wencan; Liu, Jingyong; Song, Weifeng

2010-05-15

The constant growth in generation of waste printed circuit boards (WPCB) poses a huge disposal problem because they consist of a heterogeneous mixture of organic and metallic chemicals as well as glass fiber. Also the presence of heavy metals, such as Pb and Cd turns this scrap into hazardous waste. Therefore, recycling of WPCB is an important subject not only from the recovery of valuable materials but also from the treatment of waste. The aim of this study was to present a recycling process without negative impact to the environment as an alternative for recycling WPCB. In this work, a process technology containing vacuum pyrolysis and mechanical processing was employed to recycle WPCB. At the first stage of this work, the WPCB was pyrolyzed under vacuum in a self-made batch pilot-scale fixed bed reactor to recycle organic resins contained in the WPCB. By vacuum pyrolysis the organic matter was decomposed to gases and liquids which could be used as fuels or chemical material resources, however, the inorganic WPCB matter was left unaltered as solid residues. At the second stage, the residues obtained at the first stage were investigated to separate and recover the copper through mechanical processing such as crushing, screening, and gravity separation. The copper grade of 99.50% with recovery of 99.86% based on the whole WPCB was obtained. And the glass fiber could be obtained by calcinations in a muffle furnace at 600 degrees C for 10 min. This study had demonstrated the feasibility of vacuum pyrolysis and mechanical processing for recycling WPCB. Copyright (c) 2009 Elsevier B.V. All rights reserved.

VACUUM TRAP

DOEpatents

Gordon, H.S.

1959-09-15

An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

[Non-invasive assessment of the perfusion of wounds using power Doppler imaging: vacuum assisted closure versus direct wound closure].

PubMed

Jungius, K P; Chilla, B K; Labler, L; Teodorovic, N; Marincek, B

2006-10-01

The goal of our study was to assess the perfusion in wounds treated by vacuum assisted closure (VAC) compared to primary wound closure. Power Doppler Ultrasound (PDUS) was carried out under standardised conditions in 15 VAC-treated and 10 primarily closed wounds as well as on altogether 25 intraindividual reference areas. All data were sent to a work station for post-processing to determine the perfused area. Statistical data analysis was performed with the Mann-Whitney test. Both VAC-treated wounds and primarily closed wounds showed a significant increase of the perfusion when compared to the intraindividual reference area (p < 0.0001). In VAC-treated wounds, a markedly increased perfusion was measured compared to the wounds closed primarily (p < 0.0001). Perfusion decreased during treatment, but in two VAC-treated wounds, an initial increase of the perfusion was observed. Both these wounds were grossly infected. PDUS allows the quantification of the differences in wound perfusion. This can be helpful in the detection of progressive local wound infections.

Oxygen index tests of thermosetting resins

NASA Technical Reports Server (NTRS)

Gilwee, W. J., Jr.; Parker, J. A.; Kourtides, D. A.

1980-01-01

The flammability characteristics of nine thermosetting resins under evaluation for use in aircraft interiors are described. These resins were evaluated using the Oxygen Index (ASTM 2863) testing procedure. The test specimens consisted of both neat resin and glass reinforced resin. When testing glass-reinforced samples it was observed that Oxygen Index values varied inversely with resin content. Oxygen values were also obtained on specimens exposed to temperatures up to 300 C. All specimens experienced a decline in Oxygen Index when tested at an elevated temperature.

A technological advance for 21st century obstetricians: the electronically-controlled vacuum extractor.

PubMed

Perone, Nicola

2018-04-25

To describe an innovative electronically-controlled vacuum extractor (VE) in detail and to illustrate its performance characteristics, as observed in a laboratory study. Thirty simulated, vacuum-assisted deliveries. (1) The ability to measure in real-time of the pull applied and to sound an alert, when the traction approaches the negative pressure under the cup, to prevent its detachment. (2) The recording and printing of a graphic representation of the pull applied (vacuum delivery graph). (3) The emission of a warning signal when the 15-min time limit of continuous cup application on the fetal scalp, is reached. No cup detachment occurred in any of the 15 vacuum-assisted deliveries, in which traction was kept below the adhesive force of the cup [44 lb (20 kg)], except in three cases, due to loss of negative pressure. In the remaining 15 tests, in which traction was greater than the adhesive force of the cup, "pull-offs" inevitably occurred. Furthermore, upon reaching the 15-min time limit of continuous cup application on the fetal cephalic model, a warning signal was emitted, as programmed. Conclusions We demonstrated that the electronically-controlled VE, with its distinctive pull-sensing handle, performs suitably for its intended purposes. The ability of the modernized device to decrease the incidence of cup detachment, secondary to the inadvertent application of excessive traction, may result in considerable safety, medico-legal and didactic advantages.

Phenoxy resins containing pendent ethynyl groups

NASA Technical Reports Server (NTRS)

Hergenrother, P. M.; Jensen, B. J.; Havens, S. J.

1984-01-01

As part of an effort on tougher/solvent resistant matrix resins for composites, research was directed towards exploring methods to improve the solvent resistance of linear amorphous thermoplastics. Ethyl reactive groups were placed on the ends of oligomers and pendent along the polymer chain and subsequently thermally reacted to provide crosslinking and thus improvement in solvent resistance. This concept is extended to another thermoplastic, a phenoxy resin. A commercially available phenoxy resin (PKHH) was systematically modified by reaction of the pendent hydroxyl groups on the phenoxy resin with various amounts of 4-ethynylbenzoyl chloride. As the pendent ethynyl group content in the phenoxy resin increased, the cured resin exhibited a higher glass transition temperature, better solvent resistance and less flexibility. The solvent resistance was further improved by correcting a low molecular weight diethynyl compound, 2,2-bis(4-ethynylbenzoyloxy-4'-phenyl)propane, with a phenoxy resin containing pendent ethynyl groups.

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicatemore » the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. Finally, an intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.« less

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

NASA Astrophysics Data System (ADS)

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; Leone, Stephen R.

2016-01-01

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicate the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. An intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

DOE PAGES

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; ...

2016-01-18

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicatemore » the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. Finally, an intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.« less

Pharmaceutical Applications of Ion-Exchange Resins

NASA Astrophysics Data System (ADS)

Elder, David P.

2005-04-01

The historical uses of ion-exchange resins and a summary of the basic chemical principles involved in the ion-exchange process are discussed. Specific applications of ion-exchange resins are provided. The utility of these agents to stabilize drugs are evaluated. Commonly occurring chemical and physical incompatibilities are reviewed. Ion-exchange resins have found applicability as inactive pharmaceutical constituents, particularly as disintegrants (inactive tablet ingredient whose function is to rapidly disrupt the tablet matrix on contact with gastric fluid). One of the more elegant approaches to improving palatability of ionizable drugs is the use of ion-exchange resins as taste-masking agents. The selection, optimization of drug:resin ratio and particle size, together with a review of scaleup of typical manufacturing processes for taste-masked products are provided. Ion-exchange resins have been extensively utilized in oral sustained-release products. The selection, optimization of drug:resin ratio and particle size, together with a summary of commonly occurring commercial sustained-release products are discussed. Ion-exchange resins have also been used in topical products for local application to the skin, including those where drug flux is controlled by a differential electrical current (ionotophoretic delivery). General applicability of ion-exchange resins, including ophthalmic delivery, nasal delivery, use as drugs in their own right (e.g., colestyramine, formerly referred to as cholestyramine), as well as measuring gastrointestinal transit times, are discussed. Finally, pharmaceutical monographs for ion-exchange resins are reviewed.

Epoxy resin synthesis using low molecular weight lignin separated from various lignocellulosic materials.

PubMed

Asada, Chikako; Basnet, Sunita; Otsuka, Masaya; Sasaki, Chizuru; Nakamura, Yoshitoshi

2015-03-01

A low molecular weight lignin from various lignocellulosic materials was used for the synthesis of bio-based epoxy resins. The lignin extracted with methanol from steam-exploded samples (steaming time of 5 min at steam pressure of 3.5 MPa) from different biomasses (i.e., cedar, eucalyptus, and bamboo) were functionalized by the reaction with epichlorohydrin, catalyzed by a water-soluble phase transfer catalyst tetramethylammonium chloride, which was further reacted with 30 wt% aqueous NaOH for ring closure using methyl ethyl ketone as a solvent. The glycidylated products of the lignin with good yields were cured to epoxy polymer networks with bio-based curing agents i.e., lignin itself and a commercial curing agent TD2131. Relatively good thermal properties of the bio-based epoxy network was obtained and thermal decomposition temperature at 5% weight loss (Td5) of cedar-derived epoxy resin was higher than that derived from eucalyptus and bamboo. The bio-based resin satisfies the stability requirement of epoxy resin applicable for electric circuit boards. The methanol-insoluble residues were enzymatically hydrolyzed to produce glucose. This study indicated that the biomass-derived methanol-soluble lignin may be a promising candidate to be used as a substitute for petroleum-based epoxy resin derived from bisphenol A, while insoluble residues may be processed to give a bioethanol precursor i.e., glucose. Copyright © 2015 Elsevier B.V. All rights reserved.

Relined fiberglass post: an ex vivo study of the resin cement thickness and dentin-resin interface.

PubMed

Souza, Niélli Caetano de; Marcondes, Maurem Leitão; Breda, Ricardo Vaz; Weber, João Batista Blessmann; Mota, Eduardo Gonçalves; Spohr, Ana Maria

2016-08-18

The aim of this study was to evaluate the thickness of resin cements in the root thirds when using conventional fiberglass posts (CP) and relined fiberglass posts (RP) in weakened roots and to evaluate the morphological characteristics of the dentin-resin interface. Forty human maxillary anterior teeth had the crown sectioned below the cemento-enamel junction. The canals were endodontically treated and weakened with diamond burs. Teeth were divided into four groups (n = 10): Group 1 - CP + RelyX ARC; Group 2 - CP + RelyX U200; Group 3 - RP + RelyX ARC; and Group 4 - RP + RelyX U200. Prior to luting, 0.1% Fluorescein and 0.1% Rhodamine B dyes were added to an adhesive and resin cement, respectively. Slices were obtained from the apical, middle, and cervical thirds of the root. Confocal laser scanning microscopy images were recorded in four areas (buccal, lingual, mesial, distal) of each third. In each area, four equidistant measures of the resin cement were made and the mean value was calculated. The interface morphology was observed. The data were submitted to three-way ANOVA and Tukey's test (α = 0.05). The interaction between fiberglass posts, resin cement, and root thirds was significant (p < 0.0001). The resin cement thicknesses were significantly lower for RP in comparison with CP, except in the apical third. There was no significant difference between the resin cements for RP. There was formation of resin cement tags and adhesive tags along the root for RP. RP favored the formation of thin and uniform resin cement films and resin tags in weakened roots.

Test and Analyses of a Composite Multi-Bay Fuselage Panel Under Uni-Axial Compression

NASA Technical Reports Server (NTRS)

Li, Jian; Baker, Donald J.

2004-01-01

A composite panel containing three stringers and two frames cut from a vacuum-assisted resin transfer molded (VaRTM) stitched fuselage article was tested under uni-axial compression loading. The stringers and frames divided the panel into six bays with two columns of three bays each along the compressive loading direction. The two frames were supported at the ends with pins to restrict the out-of-plane translation. The free edges of the panel were constrained by knife-edges. The panel was modeled with shell finite elements and analyzed with ABAQUS nonlinear solver. The nonlinear predictions were compared with the test results in out-of-plane displacements, back-to-back surface strains on stringer flanges and back-to-back surface strains at the centers of the skin-bays. The analysis predictions were in good agreement with the test data up to post-buckling.

Ponderosa pine resin defenses and growth: metrics matter.

PubMed

Hood, Sharon; Sala, Anna

2015-11-01

Bark beetles (Coleoptera: Curculionidae, Scolytinae) cause widespread tree mortality in coniferous forests worldwide. Constitutive and induced host defenses are important factors in an individual tree's ability to survive an attack and in bottom-up regulation of bark beetle population dynamics, yet quantifying defense levels is often difficult. For example, in Pinus spp., resin flow is important for resistance to bark beetles but is extremely variable among individuals and within a season. While resin is produced and stored in resin ducts, the specific resin duct metrics that best correlate with resin flow remain unclear. The ability and timing of some pine species to produce induced resin is also not well understood. We investigated (i) the relationships between ponderosa pine (Pinus ponderosa Lawson & C. Lawson) resin flow and axial resin duct characteristics, tree growth and physiological variables, and (ii) if mechanical wounding induces ponderosa pine resin flow and resin ducts in the absence of bark beetles. Resin flow increased later in the growing season under moderate water stress and was highest in faster growing trees. The best predictors of resin flow were nonstandardized measures of resin ducts, resin duct size and total resin duct area, both of which increased with tree growth. However, while faster growing trees tended to produce more resin, models of resin flow using only tree growth were not statistically significant. Further, the standardized measures of resin ducts, density and duct area relative to xylem area, decreased with tree growth rate, indicating that slower growing trees invested more in resin duct defenses per unit area of radial growth, despite a tendency to produce less resin overall. We also found that mechanical wounding induced ponderosa pine defenses, but this response was slow. Resin flow increased after 28 days, and resin duct production did not increase until the following year. These slow induced responses may allow

Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite.

PubMed

Hsu, Sheng-Hao; Chen, Rung-Shu; Chang, Yuan-Ling; Chen, Min-Huey; Cheng, Kuo-Chung; Su, Wei-Fang

2012-11-01

Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility

21 CFR 872.3140 - Resin applicator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3140 Resin applicator. (a) Identification. A resin applicator is a brushlike device intended for use in spreading dental resin on a tooth during application of...

Ion-to-Neutral Ratios and Thermal Proton Transfer in Matrix-Assisted Laser Desorption/Ionization

NASA Astrophysics Data System (ADS)

Lu, I.-Chung; Chu, Kuan Yu; Lin, Chih-Yuan; Wu, Shang-Yun; Dyakov, Yuri A.; Chen, Jien-Lian; Gray-Weale, Angus; Lee, Yuan-Tseh; Ni, Chi-Kung

2015-07-01

The ion-to-neutral ratios of four commonly used solid matrices, α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (2,5-DHB), sinapinic acid (SA), and ferulic acid (FA) in matrix-assisted laser desorption/ionization (MALDI) at 355 nm are reported. Ions are measured using a time-of-flight mass spectrometer combined with a time-sliced ion imaging detector. Neutrals are measured using a rotatable quadrupole mass spectrometer. The ion-to-neutral ratios of CHCA are three orders of magnitude larger than those of the other matrices at the same laser fluence. The ion-to-neutral ratios predicted using the thermal proton transfer model are similar to the experimental measurements, indicating that thermal proton transfer reactions play a major role in generating ions in ultraviolet-MALDI.

40 CFR Table 3 to Subpart Vvvv of... - MACT Model Point Value Formulas for Open Molding Operations 1

Code of Federal Regulations, 2010 CFR

2010-07-01

..., tooling resin a. Atomized 0.014 × (Resin HAP%)2.425 b. Atomized, plus vacuum bagging with roll-out 0.01185 × (Resin HAP%)2.425 c. Atomized, plus vacuum bagging without roll-out 0.00945 × (Resin HAP%)2.425 d. Nonatomized 0.014 × (Resin HAP%)2.275 e. Nonatomized, plus vaccum bagging with roll-out 0.0110 × (Resin HAP%)2...

Determination of transformation products of unsymmetrical dimethylhydrazine in water using vacuum-assisted headspace solid-phase microextraction.

PubMed

Orazbayeva, Dina; Kenessov, Bulat; Psillakis, Elefteria; Nassyrova, Dayana; Bektassov, Marat

2018-06-22

A new, sensitive and simple method based on vacuum-assisted headspace solid-phase microextraction (Vac-HSSPME) followed by gas chromatography-mass-spectrometry (GC-MS), is proposed for the quantification of rocket fuel unsymmetrical dimethylhydrazine (UDMH) transformation products in water samples. The target transformation products were: pyrazine, 1-methyl-1H-pyrazole, N-nitrosodimethylamine, N,N-dimethylformamide, 1-methyl-1Н-1,2,4-triazole, 1-methyl-imidazole and 1H-pyrazole. For these analytes and within shorter sampling times, Vac-HSSPME yielded detection limits (0.5-100 ng L -1 ) 3-10 times lower than those reported for regular HSSPME. Vac-HSSPME sampling for 30 min at 50 °C yielded the best combination of analyte responses and their standard deviations (<15%). 1-Formyl-2,2-dimethylhydrazine and formamide were discarded because of the poor precision and accuracy when using Vac-HSSPME. The recoveries for the rest of the analytes ranged between 80 and 119%. The modified Mininert valve and Thermogreen septum could be used for automated extraction as it ensured stable analyte signals even after long waiting times (>24 h). Finally, multiple Vac-HSSME proved to be an efficient tool for controlling the matrix effect and quantifying UDMH transformation products. Copyright © 2018 Elsevier B.V. All rights reserved.

ZnO synthesis by high vacuum plasma-assisted chemical vapor deposition using dimethylzinc and atomic oxygen

NASA Astrophysics Data System (ADS)

Barnes, Teresa M.; Hand, Steve; Leaf, Jackie; Wolden, Colin A.

2004-09-01

Zinc oxide thin films were produced by high vacuum plasma-assisted chemical vapor deposition (HVP-CVD) from dimethylzinc (DMZn) and atomic oxygen. HVP-CVD is differentiated from conventional remote plasma-enhanced CVD in that the operating pressures of the inductively coupled plasma (ICP) source and the deposition chamber are decoupled. Both DMZn and atomic oxygen effuse into the deposition chamber under near collisionless conditions. The deposition rate was measured as a function of DMZn and atomic oxygen flux on glass and silicon substrates. Optical emission spectroscopy and quadrupole mass spectrometry (QMS) were used to provide real time analysis of the ICP source and the deposition chamber. The deposition rate was found to be first order in DMZn pressure and zero order in atomic oxygen density. All films demonstrated excellent transparency and were preferentially orientated along the c-axis. The deposition chemistry occurs exclusively through surface-mediated reactions, since the collisionless transport environment eliminates gas-phase chemistry. QMS analysis revealed that DMZn was almost completely consumed, and desorption of unreacted methyl radicals was greatly accelerated in the presence of atomic oxygen. Negligible zinc was detected in the gas phase, suggesting that Zn was efficiently consumed on the substrate and walls of the reactor.

Vacuum-assisted stereotactic breast biopsy in the diagnosis and management of suspicious microcalcifications

PubMed Central

Esen, Gül; Tutar, Burçin; Uras, Cihan; Calay, Zerrin; İnce, Ümit; Tutar, Onur

2016-01-01

PURPOSE We aimed to present our biopsy method and retrospectively evaluate the results, upgrade rate, and follow-up findings of stereotactic vacuum-assisted breast biopsy (VABB) procedures performed in our clinic. METHODS Two hundred thirty-four patients with mammographically detected nonpalpable breast lesions underwent VABB using a 9 gauge biopsy probe and prone biopsy table. A total of 195 patients (median age 53 years, range 32–80 years) with 198 microcalcification-only lesions with a follow-up of at least one year were included in the study. The location of the lesion relative to the needle was determined from the postfire images, and unlike the conventional technique, tissue retrieval was predominantly performed from that location, followed by a complete 360° rotation, if needed. RESULTS The median core number was 8.5. Biopsy results revealed 135 benign, 24 atypical, and 39 malignant lesions. The total upgrade rate at surgery was 7.7% (6.1% for ductal carcinomas in situ and 10.5% for atypical lesions). Patients with benign lesions were followed up for a median period of 27.5 months, with no interval change. At the follow-up, scar formation was seen in 23 patients (17%); three of the scars were remarkable for resembling a malignancy. CONCLUSION Our biposy method is fast and practical, and it is easily tolerated by patients without compromising accuracy. Patients with a diagnosis of atypia still need to undergo a diagnostic surgical procedure and those with a malignancy need to undergo curative surgery, even if the lesion is totally excised at biopsy. VABB may leave a scar in the breast tissue, which may resemble a malignancy, albeit rarely. PMID:27306660

Apollo Experiment Report: Lunar-Sample Processing in the Lunar Receiving Laboratory High-Vacuum Complex

NASA Technical Reports Server (NTRS)

White, D. R.

1976-01-01

A high-vacuum complex composed of an atmospheric decontamination system, sample-processing chambers, storage chambers, and a transfer system was built to process and examine lunar material while maintaining quarantine status. Problems identified, equipment modifications, and procedure changes made for Apollo 11 and 12 sample processing are presented. The sample processing experiences indicate that only a few operating personnel are required to process the sample efficiently, safely, and rapidly in the high-vacuum complex. The high-vacuum complex was designed to handle the many contingencies, both quarantine and scientific, associated with handling an unknown entity such as the lunar sample. Lunar sample handling necessitated a complex system that could not respond rapidly to changing scientific requirements as the characteristics of the lunar sample were better defined. Although the complex successfully handled the processing of Apollo 11 and 12 lunar samples, the scientific requirement for vacuum samples was deleted after the Apollo 12 mission just as the vacuum system was reaching its full potential.

Study on properties of CFRP fabricated by VA-RTM process

NASA Astrophysics Data System (ADS)

Jeoung, Sun Kyoung; Hwang, Ye Jin; Lee, Hyun Wook; Son, Soon Keun; Kim, Hyung Sik; Ha, Jin Uk

2016-03-01

Carbon fiber reinforced plastics (CFRP) have a lot of attention from industry and academia due to its excellent mechanical property. It has been used for aircraft, automotive and so on, since it can replace metallic materials and reduce total weight with increased physical properties. However, the manufacturing process and the material cost are still challenging to be commercialized in the automotive market. Therefore, many researchers are trying to minimize materials and process cost for broadening their applications. In this study, thermoset epoxy resins were used for binder of CFRP. Epoxy resins were investigated in order to figure out optimized curing speed under vacuum assisted resin transfer molding (VARTM) processing condition. Mechanical properties of CFRP with different carbon fiber orientation and woven carbon fiber were compared to mathematically simulated results. In order to develop the application of automobile component, reliability tests of CFRP were carried out. Tensile strength of CFRP is increased when the orientation angle between fiber and axis of load was decreased (90°→ 0°). It is considered that epoxy and carbon fiber absorbed the tensile energy because the orientation of fiber and the load bearing are matched with axis direction. In addition, the CFRP automobile engine hood was fabricated by VARTM process. Drop weight impact tests (20kg & 100kg weight) were carried out in order to simulate crash performance of CFRP engine hoods.

Preparation of High Surface Area Activated Carbon from Spent Phenolic Resin by Microwave Heating and KOH Activation

NASA Astrophysics Data System (ADS)

Cheng, Song; Zhang, Libo; Zhang, Shengzhou; Xia, Hongying; Peng, Jinhui

2018-01-01

The spent phenolic resin is as raw material for preparing high surface area activated carbon (HSAAC) by microwave-assisted KOH activation. The effects of microwave power, activation duration and impregnation ratio (IR) on the iodine adsorption capability and yield of HSAAC were investigated. The surface characteristics of HSAAC were characterized by nitrogen adsorption isotherms, FTIR, SEM and TEM. The operating variables were optimized utilizing the response surface methodology (RSM) and were identified to be microwave power of 700 W, activation duration of 15 min and IR of 4, corresponding to a yield of 51.25 % and an iodine number of 2,384 mg/g. The pore structure parameters of the HSAAC, i. e., Brunauer-Emmett-Teller (BET) surface area, total pore volume, and average pore diameter were estimated to be 4,269 m2/g, 2.396 ml/g and 2.25 nm, respectively, under optimum conditions. The findings strongly support the feasibility of microwave-assisted KOH activation for preparation of HSAAC from spent phenolic resin.

Hybrid MC/QC simulations of water-assisted proton transfer in nucleosides. Guanosine and its analog acyclovir.

PubMed

Markova, Nadezhda; Pejov, Ljupco; Stoyanova, Nina; Enchev, Venelin

2017-05-01

To provide an in-depth insight into the molecular basis of spontaneous tautomerism in DNA and RNA base pairs, a hybrid Monte Carlo (MC)-quantum chemical (QC) methodology is implemented to map two-dimensional potential energy surfaces along the reaction coordinates of solvent-assisted proton transfer processes in guanosine and its analog acyclovir in aqueous solution. The solvent effects were simulated by explicit inclusion of water molecules that model the relevant part of the first hydration shell around the solute. The position of these water molecules was estimated by carrying out a classical Metropolis Monte Carlo simulation of dilute water solutions of the guanosine (Gs) and acyclovir (ACV) and subsequently analyzing solute-solvent intermolecular interactions in the statistically-independent MC-generated configurations. The solvent-assisted proton transfer processes were further investigated using two different ab initio MP2 quantum chemical approaches. In the first one, potential energy surfaces of the 'bare' finite solute-solvent clusters containing Gs/ACV and four water molecules (MP2/6-31+G(d,p) level) were explored, while within the second approach, these clusters were embedded in 'bulk' solvent treated as polarizable continuum (C-PCM/MP2/6-31+G(d,p) level of theory). It was found that in the gas phase and in water solution, the most stable tautomer for guanosine and acyclovir is the 1H-2-amino-6-oxo form followed by the 2-amino-6-(sZ)-hydroxy form. The energy barriers of the water-assisted proton transfer reaction in guanosine and in acyclovir are found to be very similar - 11.74 kcal mol -1 for guanosine and 11.16 kcal mol -1 for acyclovir, and the respective rate constants (k = 1.5 × 10 1 s -1 , guanosine and k = 4.09 × 10 1 s -1 , acyclovir), are sufficiently large to generate the 2-amino-6-(sZ)-hydroxy tautomer. The analysis of the reaction profiles in both compounds shows that the proton transfer processes occur through the

Shear Bond Strength between Fiber-Reinforced Composite and Veneering Resin Composites with Various Adhesive Resin Systems.

PubMed

AlJehani, Yousef A; Baskaradoss, Jagan K; Geevarghese, Amrita; AlShehry, Marey A; Vallittu, Pekka K

2016-07-01

The aim of this research was to evaluate the shear bond strength of different laboratory resin composites bonded to a fiber-reinforced composite substrate with some intermediate adhesive resins. Mounted test specimens of a bidirectional continuous fiber-reinforced substrate (StickNet) were randomly assigned to three equal groups. Three types of commercially available veneering resin composites - BelleGlass®, Sinfony®, and GC Gradia® were bonded to these specimens using four different adhesive resins. Half the specimens per group were stored for 24 hours; the remaining were stored for 30 days. There were 10 specimens in the test group (n). The shear bond strengths were calculated and expressed in MPa. Data were analyzed statistically, and variations in bond strength within each group were additionally evaluated by calculating the Weibull modulus. Shear bond values of those composites are influenced by the different bonding resins and different indirect composites. There was a significant difference in the shear bond strengths using different types of adhesive resins (p = 0.02) and using different veneering composites (p < 0.01). Belle-Glass® had the highest mean shear bond strength when bonded to StickNet substrate using both Prime & Bond NT and OptiBond Solo Plus. Sinfony® composite resin exhibited the lowest shear bond strength values when used with the same adhesive resins. The adhesive mode of failure was higher than cohesive with all laboratory composite resins bonded to the StickNet substructure at both storage times. Water storage had a tendency to lower the bond strengths of all laboratory composites, although the statistical differences were not significant. Within the limitations of this study, it was found that bonding of the veneering composite to bidirectional continuous fiber-reinforced substrate is influenced by the brand of the adhesive resin and veneering composite. © 2015 by the American College of Prosthodontists.

Glow discharge cleaning of vacuum switch tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, T.; Toya, H.

1991-10-01

This paper reports that glow discharge cleaning has ben advancing as a means of degassing vacuum chambers constructed for a large accelerator or for nuclear fusion research. To clean the whole surface of parts inside a vacuum switch tube (VST), a new technique is tried which generates glow discharge between the inner electrodes and copper grid surrounding it. Photographic observation reveals that the glow discharge spreads out and cleans the whole surface inside the VST. A breakdown test between the inner electrodes shows the effect of the cleaning with this technique. Higher breakdown voltage between the inner electrodes is attainedmore » by performing this glow discharge cleaning in argon rather than hydrogen gas. The difference of the cleaning effect seems to be attributed to that of the energy transfer from ion species to the absorbed molecules and microprotrusions on the surfaces.« less

Heat Flow Measurement and Analysis of Thermal Vacuum Insulation

NASA Astrophysics Data System (ADS)

Laa, C.; Hirschl, C.; Stipsitz, J.

2008-03-01

A new kind of calorimeter has been developed at Austrian Aerospace to measure specific material parameters needed for the analysis of thermal vacuum insulation. A detailed description of the measuring device and the measurement results will be given in this paper. This calorimeter facility allows to measure the heat flow through the insulation under vacuum conditions in a wide temperature range from liquid nitrogen to ambient. Both boundary temperatures can be chosen within this range. Furthermore the insulation can be characterized at high vacuum or under degraded vacuum, the latter is simulated by using helium or nitrogen gas. The mechanisms of heat transfer have been investigated, namely infrared radiation between the reflective layers of the insulation and conduction through the interleaving spacer material. A mathematical description of the heat flow through the insulation has been derived. Based on this, the heat flow for a typical insulation material has been calculated by finite element analysis by use of the sotware tool Ansys®. Such a transient calculation is needed to determine the time to reach thermal equilibrium, which is mandatory for a proper interpretation and evaluation of the measurement. The new insulation measurement results combined with the proposed type of analysis can be applied to better understand the thermal behavior of any kind of cryogenic system.

Head flying characteristics in heat assisted magnetic recording considering various nanoscale heat transfer models

NASA Astrophysics Data System (ADS)

Hu, Yueqiang; Wu, Haoyu; Meng, Yonggang; Wang, Yu; Bogy, David

2018-01-01

The thermal issues in heat-assisted magnetic recording (HAMR) technology have drawn much attention in the recent literature. In this paper, the head flying characteristics and thermal performance of a HAMR system during the touch-down process considering different nanoscale heat transfer models across the head-disk interface are numerically studied. An optical-thermal-mechanical coupled model is first described. The coupling efficiency of the near field transducer is found to be dependent on the head disk clearance. The shortcomings of a constant disk-temperature model are investigated, which reveals the importance of considering the disk temperature as a variable. A study of the head flying on the disk is carried out using an air conduction model and additional near-field heat transfer models. It is shown that when the head disk interface is filled with a solid material caused by the laser-induced accumulation, the heat transfer coefficient can become unexpectedly large and the head's temperature can rise beyond desirable levels. Finally, the additional head protrusion due to the laser heating is investigated.

Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling

NASA Astrophysics Data System (ADS)

Donnarumma, Fabrizio; Camp, Eden E.; Cao, Fan; Murray, Kermit K.

2017-09-01

Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. [Figure not available: see fulltext.

Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling.

PubMed

Donnarumma, Fabrizio; Camp, Eden E; Cao, Fan; Murray, Kermit K

2017-09-01

Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. Graphical Abstract ᅟ.

Thermal transfer recording media

NASA Astrophysics Data System (ADS)

Takei, T.; Taniguchi, M.; Fukushima, H.; Yamaguchi, Y.; Shinozuka, M.; Seikohsha, K. K. Suwa

1988-08-01

The recording media consist of more than or one coloring layer and a layer containing a flame retardant to ensure noncombustibility and good thermal transfer. Thus, a PET film was coated on a side with a compound containing Vylon 290 (polyester resin), AFR-1021 (decabromodiphenyl oxide) 8 and Polysafe 60 (Sb oxide), and coated on the other side with a compound containing carnauba wax, HNP-9 (paraffin wax), EV-410 (ethylene-vinyl acetate copolymer), and Cu phthalocyanine to give a thermal transfer recording medium which showed good noncombustibility and antiblocking properties, and provided high quality images.

Comparison of vacuum and non-vacuum urine tubes for urinary sediment analysis.

PubMed

Topcuoglu, Canan; Sezer, Sevilay; Kosem, Arzu; Ercan, Mujgan; Turhan, Turan

2017-12-01

Urine collection systems with aspiration system for vacuum tubes are becoming increasingly common for urinalysis, especially for microscopic examination of the urine. In this study, we aimed to examine whether vacuum aspiration of the urine sample has any adverse effect on sediment analysis by comparing results from vacuum and non-vacuum urine tubes. The study included totally 213 urine samples obtained from inpatients and outpatients in our hospital. Urine samples were collected to containers with aspiration system for vacuum tubes. Each sample was aliquoted to both vacuum and non-vacuum urine tubes. Urinary sediment analysis was performed using manual microscope. Results were evaluated using chi-square test. Comparison of the sediment analysis results from vacuum and non-vacuum urine tubes showed that results were highly concordant for erythrocyte, leukocyte and epithelial cells (gamma values 1, 0.997, and 0.994, respectively; p < .001). Results were also concordant for urinary casts, crystals and yeast (kappa values 0.815, 0.945 and 1, respectively; p < .001). The results show that in urinary sediment analysis, vacuum aspiration has no adverse effect on the cellular components except on casts.

[Physical properties of resins for veneer crown. (Part 1) Bending strength of thermosetting methacrylic resins (author's transl)].

PubMed

Kashiwada, T

1979-01-01

The physical properties of thermosetting methacrylic resins contain a kind or more than two kinds of cross linking agents were investigated. Knoop hardness and bending strength after drying, water sorption and thermal cycling were listed in table 4 and 5. Hydrophilic resins absorbed water about 3 times as much as hydrophobic resins. The materials contain a small amount of hydrophobic cross linking agents in MMA indicate comparatively excellent properties after drying, water sorption and thermal cycling. Knoop hardness of resins generally reduced by water sorption, especially in the case of the resin contains a large amount of triethylene glycol dimethacrylate.

Non-classicality of the molecular vibrations assisting exciton energy transfer at room temperature

PubMed Central

O’Reilly, Edward J.; Olaya-Castro, Alexandra

2014-01-01

Advancing the debate on quantum effects in light-initiated reactions in biology requires clear identification of non-classical features that these processes can exhibit and utilize. Here we show that in prototype dimers present in a variety of photosynthetic antennae, efficient vibration-assisted energy transfer in the sub-picosecond timescale and at room temperature can manifest and benefit from non-classical fluctuations of collective pigment motions. Non-classicality of initially thermalized vibrations is induced via coherent exciton–vibration interactions and is unambiguously indicated by negativities in the phase–space quasi-probability distribution of the effective collective mode coupled to the electronic dynamics. These quantum effects can be prompted upon incoherent input of excitation. Our results therefore suggest that investigation of the non-classical properties of vibrational motions assisting excitation and charge transport, photoreception and chemical sensing processes could be a touchstone for revealing a role for non-trivial quantum phenomena in biology. PMID:24402469

Biocompatibility of composite resins

PubMed Central

Mousavinasab, Sayed Mostafa

2011-01-01

Dental materials that are used in dentistry should be harmless to oral tissues, so they should not contain any leachable toxic and diffusible substances that can cause some side effects. Reports about probable biologic hazards, in relation to dental resins, have increased interest to this topic in dentists. The present paper reviews the articles published about biocompatibility of resin-restorative materials specially resin composites and monomers which are mainly based on Bis-GMA and concerns about their degradation and substances which may be segregated into oral cavity. PMID:23372592

Research on thermal conductivity of HGMs at vacuum in room temperature

NASA Astrophysics Data System (ADS)

Wang, Ping; Liao, Bin; An, Zhenguo; Yan, Kaiqi; Zhang, Jingjie

2018-05-01

Hollow glass microspheres (HGMs) can be used as thermal insulation materials owing to its hollow structure which brings excellent thermal insulation property and low density. At present, most researches on thermal conductivity of HGMs are focused on polymer matrix/HGMs composite materials. However, thermal conductivity of HGMs at vacuum in room temperature has rarely been investigated. In this work, thermal conductivity of six types of HGMs (T17 (0.17g/cm3), T20 (0.20g/cm3), T22 (0.22g/cm3), T25 (0.25g/cm3), T32 (0.32g/cm3) and T40 (0.40g/cm3)) at vacuum in room temperature were calculated by heat transfer of solid conduction and radiation. The calculation results showed that thermal conductivity of HGMs would be decreased by an order of magnitude compared with no vacuum. In order to verify the calculation and study vacuum thermal insulation properties of HGMs, thermal conductivity of above-mentioned HGMs at no vacuum and high vacuum in room temperature were measured by a self-made thermal conductivity measuring apparatus which was based on the transient plane source (TPS) method. The experimental results showed that thermal conductivity of HGMs were in the range of 4.2030E-02 to 6.3300E-02 W/m.K (at no vacuum) and 3.8160E-03 to 4.9660E-03 W/m.K (at high vacuum). The results indicated that experimental thermal conductivity was consistent with the calculation results and both of them were all decreased by 8-13 times at vacuum compared with no vacuum. In addition, the relationship with physical properties and thermal conductivity of HGMs has been discussed in detail. In conclusion, HGMs possess excellent thermal insulation performance at high vacuum in room temperature and have potential to further reduce thermal conductivity at the same conditions.

Femtosecond laser printing of living cells using absorbing film-assisted laser-induced forward transfer

NASA Astrophysics Data System (ADS)

Hopp, Béla; Smausz, Tomi; Szabó, Gábor; Kolozsvári, Lajos; Kafetzopoulos, Dimitris; Fotakis, Costas; Nógrádi, Antal

2012-01-01

The applicability of a femtosecond KrF laser in absorbing film-assisted, laser-induced forward transfer of living cells was studied. The absorbing materials were 50-nm-thick metal films and biomaterials (gelatine, Matrigel, each 50 μm thick, and polyhydroxybutyrate, 2 μm). The used cell types were human neuroblastoma, chronic myeloid leukemia, and osteogenic sarcoma cell lines, and primary astroglial rat cells. Pulses of a 500-fs KrF excimer laser focused onto the absorbing layer in a 250-μm diameter spot with 225 mJ/cm2 fluence were used to transfer the cells to the acceptor plate placed at 0.6 mm distance, which was a glass slide either pure or covered with biomaterials. While the low-absorptivity biomaterial absorbing layers proved to be ineffective in transfer of cells, when applied on the surface of acceptor plate, the wet gelatine and Matrigel layers successfully ameliorated the impact of the cells, which otherwise did not survive the arrival onto a hard surface. The best short- and long-term survival rate was between 65% and 70% for neuroblastoma and astroglial cells. The long-term survival of the transferred osteosarcoma cells was low, while the myeloid leukemia cells did not tolerate the procedure under the applied experimental conditions.

Characterization of Composite Fan Case Resins

NASA Technical Reports Server (NTRS)

Dvoracek, Charlene M.

2004-01-01

The majority of commercial turbine engines that power today s aircraft use a large fan driven by the engine core to generate thrust which dramatically increases the engine s efficiency. However, if one of these fan blades fails during flight, it becomes high energy shrapnel, potentially impacting the engine or puncturing the aircraft itself and thus risking the lives of passengers. To solve this problem, the fan case must be capable of containing a fan blade should it break off during flight. Currently, all commercial fan cases are made of either just a thick metal barrier or a thinner metal wall surrounded by Kevlar-an ultra strong fiber that elastically catches the blade. My summer 2004 project was to characterize the resins for a composite fan case that will be lighter and more efficient than the current metal. The composite fan case is created by braiding carbon fibers and injecting a polymer resin into the braid. The resin holds the fibers together, so at first using the strongest polymer appears to logically lead to the strongest fan case. Unfortunately, the stronger polymers are too viscous when melted. This makes the manufacturing process more difficult because the polymer does not flow as freely through the braid, and the final product is less dense. With all of this in mind, it is important to remember that the strength of the polymer is still imperative; the case must still contain blades with high impact energy. The research identified which polymer had the right balance of properties, including ease of fabrication, toughness, and ability to transfer the load to the carbon fibers. Resin deformation was studied to better understand the composite response during high speed impact. My role in this research was the testing of polymers using dynamic mechanical analysis and tensile, compression, and torsion testing. Dynamic mechanical analysis examines the response of materials under cyclic loading. Two techniques were used for dynamic mechanical analysis

Early hardness of self-adhesive resin cements cured under indirect resin composite restorations.

PubMed

Giráldez, Isabel; Ceballos, Laura; Garrido, Miguel A; Rodríguez, Jesús

2011-04-01

To determine the influence of curing mode on the surface hardness of seven resin cements used to lute indirect composite restorations. Seven commercial dual-curing resin cements were tested: two were total-etch (RelyX ARC [3M ESPE, St. Paul, MN, USA] and Variolink II [Ivoclar Vivadent, Schaan, Liechtenstein]); one was self-etch (Multilink Automix [Ivoclar Vivadent]), and four were self-adhesive (RelyX Unicem [3M ESPE], Maxcem Elite [Kerr Corp., Orange, CA, USA], SmartCem2 [Dentsply, Detrey, GmbH, Konstanz, Germany], and G-Cem [GC CORPORATION, Itabashi-Ku, Tokyo, Japan]). Three specimens (0.5 × 6.5mm) of each material were prepared for each of three experimental groups: Group 1 (cements allowed to self cure); Group 2 (cements light-cured for 40 seconds); and Group 3 (cements light-cured for 80 seconds). All specimens were cured through a 4-mm-thick composite cylinder (Filtek Z250-A3). Surface microhardness numbers were determined at 20 min after preparation. Results were analyzed by two-way analysis of variance and Student-Newman-Keuls tests (p<0.05). Superficial hardness was significantly influenced by the resin cement tested (p<0.0001), the curing mode (p<0.0001), and their interaction (p<0.0001). RelyX ARC exhibited the highest mean microhardness values regardless of the curing mode. Light-curing significantly increased the microhardness of all resin cements studied, and these values increased even further with a doubling of irradiation time. Self-adhesive cements exhibited different behavior according to the curing mode. RelyX Unicem was highly sensitive to light irradiation, showing the lowest mean values in the self-curing mode. After light irradiation for 40 or 80 seconds, Maxcem Elite exhibited the lowest mean hardness values of all the resin cements tested. The microhardness of resin cements is highly dependent on the brand. Dual-curing resin cements should always be light irradiated for longer periods than that recommended by manufacturers. Dual

Demonstration of New, Highly Perchlorate-Selective Ion Exchange Resin Coupled with Resin-Optimized, Single-Vessel Engineering Design

DTIC Science & Technology

2013-03-01

effluent by ion chromatography (method described in Appendix A) Resin Separation Will remove >95% of fully exhausted resin (below mid-lateral...and retain >95% of the unexhausted resin (above the mid-lateral). 1) Mass balance on ClO4- during each cycle using ion chromatography and resin...Application Note 134, “Determination of Low Concentrations of Perchlorate in Drinking and Ground Waters Using Ion Chromatography ” and Product Note

From Vacuum Tubes to a Semiconductor Triode

NASA Astrophysics Data System (ADS)

Mil'shtein, S.

2005-06-01

Current study presents a brief review of an electronic technology evolution: from vacuum tubes, to transistors, to a novel, recently developed semiconductor triode, where electrons travel vertically about 600 angstroms from the filament to the anode. We plotted I-V and transfer curves for the semiconductor triodes. The very first prototypes proved to carry a maximum gain of about 15db and fT=8GHz. Filaments of variable length were produced to study mutual electrostatic interaction of the electrodes in the triode.

Ultrasound-guided cable-free 13-gauge vacuum-assisted biopsy of non-mass breast lesions

PubMed Central

Seo, Jiwoon; Jang, Mijung; Yun, Bo La; Lee, Soo Hyun; Kim, Eun-Kyu; Kang, Eunyoung; Park, So Yeon; Moon, Woo Kyung; Choi, Hye Young; Kim, Bohyoung

2017-01-01

Purpose To compare the outcomes of ultrasound-guided core biopsy for non-mass breast lesions by the novel 13-gauge cable-free vacuum-assisted biopsy (VAB) and by the conventional 14-gauge semi-automated core needle biopsy (CCNB). Materials and methods Our institutional review board approved this prospective study, and all patients provided written informed consent. Among 1840 ultrasound-guided percutaneous biopsies performed from August 2013 to December 2014, 145 non-mass breast lesions with suspicious microcalcifications on mammography or corresponding magnetic resonance imaging finding were subjected to 13-gauge VAB or 14-gauge CCNB. We evaluated the technical success rates, average specimen numbers, and tissue sampling time. We also compared the results of percutaneous biopsy and final surgical pathologic diagnosis to analyze the rates of diagnostic upgrade or downgrade. Results Ultrasound-guided VAB successfully targeted and sampled all lesions, whereas CCNB failed to demonstrate calcification in four (10.3%) breast lesions with microcalcification on specimen mammography. The mean sampling time were 238.6 and 170.6 seconds for VAB and CCNB, respectively. No major complications were observed with either method. Ductal carcinoma in situ (DCIS) and atypical ductal hyperplasia (ADH) lesions were more frequently upgraded after CCNB (8/23 and 3/5, respectively) than after VAB (2/26 and 0/4, respectively P = 0.028). Conclusion Non-mass breast lesions were successfully and accurately biopsied using cable-free VAB. The underestimation rate of ultrasound-detected non-mass lesion was significantly lower with VAB than with CCNB. Trial registration CRiS KCT0002267. PMID:28628656

Synthesis and characterizations of melamine-based epoxy resins.

PubMed

Ricciotti, Laura; Roviello, Giuseppina; Tarallo, Oreste; Borbone, Fabio; Ferone, Claudio; Colangelo, Francesco; Catauro, Michelina; Cioffi, Raffaele

2013-09-05

A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials.

Synthesis and Characterizations of Melamine-Based Epoxy Resins

PubMed Central

Ricciotti, Laura; Roviello, Giuseppina; Tarallo, Oreste; Borbone, Fabio; Ferone, Claudio; Colangelo, Francesco; Catauro, Michelina; Cioffi, Raffaele

2013-01-01

A new, easy and cost-effective synthetic procedure for the preparation of thermosetting melamine-based epoxy resins is reported. By this innovative synthetic method, different kinds of resins can be obtained just by mixing the reagents in the presence of a catalyst without solvent and with mild curing conditions. Two types of resins were synthesized using melamine and a glycidyl derivative (resins I) or by adding a silane derivative (resin II). The resins were characterized by means of chemical-physical and thermal techniques. Experimental results show that all the prepared resins have a good thermal stability, but differ for their mechanical properties: resin I exhibits remarkable stiffness with a storage modulus value up to 830 MPa at room temperature, while lower storage moduli were found for resin II, indicating that the presence of silane groups could enhance the flexibility of these materials. The resins show a pot life higher than 30 min, which makes these resins good candidates for practical applications. The functionalization with silane terminations can be exploited in the formulation of hybrid organic-inorganic composite materials. PMID:24013372

A versatile approach to vacuum injection casting for materials research and development.