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Liu, Mu-Yi, Tsung-Ting Tsai, Lih-Huei Chen, Wen-Huang Liang, Po-Liang Lai, and Ching-Lung Tai. "Biomechanical Comparison of Lumbar Motion Unit Stability Following Posterior Instrumentation with Facet Spacers and Facet Screws." Journal of Medical and Biological Engineering 40, no. 2 (November 27, 2019): 220–29. http://dx.doi.org/10.1007/s40846-019-00501-x.
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Abstract Purpose Lumbar posterior instrumentation for facet stabilization has become popular for the treatment of lumbar instability. The present study investigated and compared facet stabilization following lumbar posterior instrumentation with facet spacers and facet screws using porcine lumbar spines. Methods Eighteen L5–L6 lumbar motion units (LMUs) of the porcine spines were randomly divided into three groups (un-instrumented, facet-spacer and facet-screw). In the un-instrumented group (control), all ligamentous structures were preserved. In the facet-spacer group, two facet spacers were inserted into the joint spaces of the bilateral upper and lower facets. In the facet-screw group, two cannulated screws were used to transfix the bilateral upper and lower facets. With the use of a material testing machine, a gradually increasing moment of up to 6000 N-mm was generated in flexion, extension, lateral bending and torsion motions to compare facet stabilization among the groups. Results The facet-spacer group was significantly stiffer than the facet-screw group in extension (p = 0.013), whereas the facet-screw group was significantly stiffer than the facet-spacer group in axial rotation (p = 0.004). No statistically significant differences were observed between the two fixation techniques in flexion (p = 0.284) and lateral bending (p = 0.085). Conclusion Both facet-spacer and facet-screw fixation techniques significantly improve stability in a single LMU. Facet-spacer fixation provided better stabilization in extension, while facet-screw fixation provided better stabilization in axial rotation.
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Moerenhout, K., S. Steinmetz, M. Vautrin, S. Picarra, G. Udin, and O. Borens. "Economic advantage of ‘self-made’ antibiotic-loaded spacer compared to prefabricated antibiotic-loaded spacer and spacer molds in two-staged revision arthroplasty." Acta Orthopaedica Belgica 87, no. 3 (September 30, 2021): 557–62. http://dx.doi.org/10.52628/87.3.24.
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Infection after total hip or total knee arthroplasty is a serious complication implying great costs for the health care system. Amongst the different treatment options, the two-step exchange using a spacer in the interval is a valid option. We evaluate the economic impact of our self-made antibiotic-loaded hip and knee cement spacers compared with prefabricated spacers and spacer molds. Costs to prepare self-made cement spacers are detailed for each spacer type. We also assess the intraoperative time spent for fabricating our self-made hip and knee spacers. The price of these self-made knee spacer is 514 CHF (450 EUR / 505 USD) if non-articulated and 535 CHF (470 EUR / 525 USD) if articulated ; the price for the self-made hip spacer is 749 CHF (760 EUR / 735 USD). Our average preparation time is 14 minutes for our self-made knee spacers and 16 minutes for our self-made hip spacers. While the senior surgeon is fabricating the self-spacers, another surgeon of the team continues intensive irrigation and debridement. Thus, no time is lost waiting for the self-spacer to be fabricated. In our hands, self-made hip and knee spacers are at least 40-50% cheaper than prefabricated spacers and spacer-molds. This is a serious economic advantage in this already expensive surgery. When done in teamwork, self-spacer fabrication does not increase the surgery time. The economic advantage is added to the main and most important advantage of self- made spacers, which remains the possibility of patient adapted anatomical reconstruction of the joint.
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Citak, Mustafa, Bassam A. Masri, Bryan Springer, Jean-Noel Argenson, and Daniel O. Kendoff. "Are Preformed Articulating Spacers Superior To Surgeon-Made Articulating Spacers in the Treatment Of PJI in THA? A Literature Review." Open Orthopaedics Journal 9, no. 1 (July 31, 2015): 255–61. http://dx.doi.org/10.2174/1874325001509010255.
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Background and Purpose: Antibiotic-loaded cement spacers are typically manufactured by surgeons in the operating room. However, if the infecting organism is known preoperatively, the cement spacer can be fabricated (Spacer-G® or the InterSpace® Hip) in advance. It is unclear if preformed hip spacers are superior to surgeon-made hip spacers in the treatment of periprosthetic joint infection following primary THA. Methods: A literature review of the peer-reviewed literature indexed by MEDLINE and Embase was performed to identify studies reporting the outcomes of preformed and surgeon-made hip spacers in the treatment of infection following primary total hip arthroplasty (THA). A total of 43 articles met the inclusion criteria and were included in the analysis to compare the reinfection rate, Harris Hip Score (HHS) and spacer complication rates between surgeon-made and preformed hip spacers. Results and Interpretation: The analyzed studies included a total number of 1631 infected THA cases (n=1027 surgeonmade; n=604 preformed spacers). We found similar reinfection rates (6.0% surgeon-made, and 5.5% preformed spacers) and similar mean HHS at latest follow-up after reimplantation (HHS=84.3 surgeon-made, and HHS=81.8 preformed spacers) between both groups. However, patients treated with a surgeon-made articulating spacer had a higher spacer fracture rate compared to preformed articulating spacer. The use of preformed articulating spacers in the treatment of infected THA is not superior to surgeon-made articulating spacers regarding infection control and functional outcomes. However, the use of surgeon-made antibiotic spacers increased the risk of spacer fracture.
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Anagnostakos, Konstantinos, and Christof Meyer. "Antibiotic Elution from Hip and Knee Acrylic Bone Cement Spacers: A Systematic Review." BioMed Research International 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/4657874.
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Knowledge about the elution from antibiotic-loaded cement spacers is an indispensable premise for guarantee of clinical success. A systematic literature search was performed through PubMed. Search terms were “antibiotic elution” and “antibiotic release” in combination with “spacer,” “hip spacer,” and “knee spacer,” respectively. A total of 11 studies could be identified. Seven studies reported on the release of antibiotics after spacer implantation, three studies at spacer removal, and one study on both time points. Seven studies reported on hip spacers, one study on knee spacers, and three studies on both. In eight studies, custom-made spacers have been implanted and in three prefabricated ones. In the majority of the studies, the cement has been loaded with an antibiotic combination, mostly consisting of aminoglycoside (either gentamicin or tobramycin) and vancomycin. Measured concentrations exceeded the minimal inhibitory concentration of the particular pathogen organisms in each case. However, large discrepancies were observed with regard to the height of the antibiotic concentration depending on the antibiotic combination and the antibiotic ratio used. Current literature data indicate a sufficient elution of antibiotics after spacer implantation and at spacer removal, respectively. Future studies are required to optimize the local antibiotic therapy at the site of spacer implantation.
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Iguchi, Tetsuhiro, Aritetsu Kanemura, Akira Kurihara, Koichi Kasahara, Shinichi Yoshiya, Minoru Doita, and Kotaro Nishida. "Cervical laminoplasty: evaluation of bone bonding of a high porosity hydroxyapatite spacer." Journal of Neurosurgery: Spine 98, no. 2 (March 2003): 137–42. http://dx.doi.org/10.3171/spi.2003.98.2.0137.
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Object. The purpose of this study was to evaluate the usefulness of a high-porosity hydroxyapatite (HA) spacer in cervical laminoplasty. Bone—spacer bonding rates, complications associated with the implant, and factors related to bone bonding were examined. Methods. The authors evaluated 33 consecutive patients with cervical myelopathy who underwent high-porosity HA spacer—assisted laminoplasty and were followed for at least 1 year (mean 30 months). The results of bone—spacer bonding of the 147 implants were evaluated using computerized tomography (CT) scanning. The symptoms significantly improved in 30 patients. No difference in results was detected between patients with cervical spondylosis and those with ossification of posterior longitudinal ligament. Breakage of seven spacers occurred in four patients without causing neck pain or neurological deficits. There were no other HA spacer—related complications. The spacers became rigidly bound to bone in 61% of the cases, and bone regrowth developed around the spacer in 91%. The rate of bone—spacer bonding increased over time, and the CT-documented attenuation value (Hounsfield unit) of the spacer adjacent to the bone—spacer junction in the group in which union occurred was significantly higher than in the nonunion group. Conclusions. High-porosity HA spacer—augmented laminoplasty produced good bonding-related results. Bone bonding continued to progress 1 year after surgery, indicating the good osteoconductive capability of high-porosity HA. To avoid breakage of a spacer, a minimum 7-mm distance between spacers is necessary.
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Lesmana, Andrean, Amira Permatasari Tarigan, and Fajrinur Syarani. "Effectiveness of administration of bronchodilator by spacers, home-made spacers and nebulizers in patients with chronic obstructive pulmonary disease." International Journal of Research in Medical Sciences 7, no. 6 (May 29, 2019): 2417. http://dx.doi.org/10.18203/2320-6012.ijrms20192540.
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Background: In chronic obstructive pulmonary disease (COPD), bronchodilator therapy using dry powder inhaler (DPI) or a measured dose inhaler (MDI) is more convenient at a lower cost than nebulizer therapy. Mistakes in the use of MDI often occur due to lack of coordination but with the addition of spacers, drawbacks in the use of this MDI can be overcome so that it does not require coordination. Commercial spacers are relatively expensive and not available anywhere while home-made spacers made from bottles of mineral water are very cheap and can be made alone. Study aimed to evaluate the effectiveness of each device, namely a spacer, a home-made spacer and nebulizer.Methods: This study is an experimental study of 62 COPD patients who received bronchodilators using spacers, home-made spacers, and nebulizers. Spirometry is performed for each sample before and after bronchodilator administration to assess FEV1, KVP and changes in VAS dyspnea. The difference in the effectiveness of bronchodilators for various devices in COPD patients was statistically analyzed using the ANOVA test.Results: There were significant differences in the values of VEP1, KVP and VAS dyspnoea after bronchodilator administration through the spacer, home-made spacer and nebulizer (p<0.001), (p=0.002), (p<0.001). The increase in% VEP1 with a nebulizer device was higher than that of a spacer (p=0.001) and the increase in% VEP1 with the nebulizer device was also significantly significant compared to home-made spacer (p<0.001). The increase in% KVP with the nebulizer device was higher than that of home-made spacer (p<0.001), as well as between spacers and home-made spacers and this was significant (p=0.038). The decrease in VAS dyspnoea in patients using nebulizer device than the spacer (p<0.001). Decreasing VAS dyspnoea with nebulizer devices is higher compared to home-made spacers, also gives significant results (p<0.001). There were no differences in the decrease in VAS dyspnoea between spacers and home-made spacers.Conclusions: The administration of bronchodilators by use of three devices (spacers, home-made spacers and nebulizers) can significantly increase the values of FEV1, KVP and VAS dyspnoea. On the use of spacers and home-made spacers, the increase of pulmonary physiological values is not significantly different.
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Yang, Yibo, Chen Huang, Wenying Guo, Hui Zhao, Zhenjie Li, Jiankuan Li, Jianyong Bao, and Hengchang Wang. "Study of the Effect of Surface Treatment on the Chloride Ion Transport at the Cementitious Spacer–Concrete Interface." Applied Sciences 10, no. 15 (July 28, 2020): 5196. http://dx.doi.org/10.3390/app10155196.
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Spacers are important components in reinforced concrete structures to provide cover between the steel reinforcement and the formwork. Cementitious spacers are of particular interest for coastal engineering structures, as they are compatible with cement-based chloride-resistant high-performance concrete compared to plastic and steel spacers. However, the cementitious spacer–concrete interface was found to be highly porous and microcracked. This study investigated the effect of surface treatment on the chloride ion transport at the cementitious spacer–concrete interface. A surface treatment technique for potential mass production was introduced and the state-of-practice tests of the hardened concrete were modified to evaluate the performance of the spacer–concrete composite specimens. The results showed that the surface treatment on a cementitious spacer improved the bonding between the spacer and concrete at the interface. The surface treatment of the spacer improved the compressive strength and the chloride resistance of the composite specimen locally compared to those without surface treatment. The advantage of surface treatment on the chloride resistance was partially represented in either the diffusion coefficient or the column electric flux. The maximum chloride ion penetration depth at the spacer–concrete interface was recommended as an additional proxy for the evaluation of the chloride resistance performance of composite specimens.
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Pisárčik, Martin, and Ferdinand Devínsky. "Surface tension study of cationic gemini surfactants binding to DNA." Open Chemistry 12, no. 5 (May 1, 2014): 577–85. http://dx.doi.org/10.2478/s11532-014-0513-7.
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AbstractBinding of cationic gemini surfactants alkanediyl-a-ω-bis(dimethyldodecylammonium bromides) with variable polymethylene spacer length ranging from 2 to 12 methylene groups to DNA in NaBr solution is investigated utilizing the tensiometry method. A simple method is presented for calculating the number of surfactant molecules bound to DNA. The results are evaluated in terms of the gemini surfactant spacer length, showing that gemini molecules with either short spacers (2 methylene groups) or long spacers are most efficiently adsorbed to DNA. A weak adsorption to DNA was found for gemini molecules with a medium spacer length (6 methylene groups in the spacer). The binding properties of cationic gemini surfactants as a function of spacer length are consistent with the results obtained by other experimental methods (dynamic light scattering measurements, fluorescence spectroscopy), indicating identical adsorption behaviour of gemini molecules as a function of the spacer length.
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WIATER, Jaroslaw. "Failures of Lightning Air-Termination Rods Fixed by Spacers." AUTOMATYKA, ELEKTRYKA, ZAKLOCENIA 12, no. 2(44)2021 (June 30, 2021): 36–41. http://dx.doi.org/10.17274/aez.2021.44.02.
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Air-termination rods with height above 2,5 m must be fixed to objects by for example spacer bars to ensure proper separation distance. Commercially available spacer bars are suitable in laboratory conditions only. Real-life scenarios show weak points of this solution. Dirty or wet spacers do not fulfil proper isolation strength to ensure proper separation distance. This changes the km factor used to calculate the separation distance. The paper presents laboratory tests for clean spacers, wet spacers and a few real photos of damage caused by spacer bars.
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Kenyon, CJ, L. Thorsson, L. Borgstrom, and SP Newman. "The effects of static charge in spacer devices on glucocorticosteroid aerosol deposition in asthmatic patients." European Respiratory Journal 11, no. 3 (March 1, 1998): 606–10. http://dx.doi.org/10.1183/09031936.98.11030606.
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Electrostatic charge in plastic spacer devices has been shown in vitro to reduce delivery of asthma medications intended for inhalation, but the effect of static charge on in vivo drug deposition is unknown. A six-way randomized crossover study was conducted in 10 mild asthmatic patients. Two plastic spacers (Nebuhaler and Volumatic) and one metal spacer (Nebuchamber) were tested. The spacers were used either "primed" or "unprimed". Priming was performed by firing 20 doses of placebo aerosol into a new spacer, hence coating the inner surface with surfactant and minimizing static charge. Unprimed spacers were new and were not treated. Pressurized aerosol canisters delivering budesonide (200 microg Pulmicort) were radiolabelled with the radionuclide 99mTc and lung deposition was measured by gamma scintigraphy. The radiolabel was shown to be a valid marker for the drug substance prior to the clinical phase of the study. Priming significantly increased mean whole lung deposition following inhalation from plastic spacers (Nebuhaler primed 37.7% and unprimed 26.7%, p=0.01; Volumatic primed 32.0% and unprimed 22.1%, p=0.02). Priming had no effect on the mean whole lung deposition following inhalation from the Nebuchamber (primed 33.5% and unprimed 32.9%). Lung deposition in vivo from plastic spacer devices will vary according to the electrostatic charge on the spacer walls. Priming reduces retention of drug on plastic spacer devices and increases lung deposition. Metal spacers are not susceptible to static charge, which should result in more predictable lung deposition.
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Mao, L., F. Lagarde, J. Guo, X. Wang, J. Li, Q. Shen, J. Zhu, and H. Yang. "Performance study of large-area glass resistive plate chambers with different spacer configurations." Journal of Instrumentation 16, no. 12 (December 1, 2021): P12022. http://dx.doi.org/10.1088/1748-0221/16/12/p12022.
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Abstract Optimization of spacer and gas distribution inside the glass resistive plate chamber (RPC) is reported. Simulation studies demonstrate improvements on the gas flow velocity homogeneity and lower vorticity inside the gas chamber. The optimized spacer configuration (76 spacers) decreases the number of spacers by 24% compared to the original design (100 spacers), thus helps significantly reduce the non-active or low-efficiency area caused by spacers while maintaining similar deformation uniformity of the electrodes. Large area glass RPCs with 1×1 m^2 size using two types of spacer configurations are constructed and tested with cosmic muons events. The muon detection efficiencies for RPCs are greater than 95%.
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Li, Zhe Fei, Jian Xie, Lia Stanciu, and Yang Ren. "Nanostructured Graphenes and Metal Oxides for Fuel Cell and Battery Applications." Advanced Materials Research 705 (June 2013): 126–31. http://dx.doi.org/10.4028/www.scientific.net/amr.705.126.
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Graphene/spacer nanoparticle composites were prepared by reducing graphene oxide with hydrazine in the presence of different contents of polyaniline nanoparticles. In-situ cryo-TEM image of GO-spacer solution shows that spacer nanoparticles are anchored on GO sheets. During the reduction, as-adsorbed spacer nanoparticles were sandwiched between layers of graphene. These spacer nanoparticles act as spacers to create gaps between neighboring graphene sheets, resulting in higher surface area. Graphene/spacer nanocomposites exhibited highest specific surface area of 1500 m2/g. Utilizing this composite material, a supercapacitor with specific capacitance of 267 F/g at a current density of 0.1 A/g was achieved.
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Mojica, F. J. M., C. Díez-Villaseñor, J. García-Martínez, and C. Almendros. "Short motif sequences determine the targets of the prokaryotic CRISPR defence system." Microbiology 155, no. 3 (March 1, 2009): 733–40. http://dx.doi.org/10.1099/mic.0.023960-0.
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Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated CRISPR-associated sequence (CAS) proteins constitute a novel antiviral defence system that is widespread in prokaryotes. Repeats are separated by spacers, some of them homologous to sequences in mobile genetic elements. Although the whole process involved remains uncharacterized, it is known that new spacers are incorporated into CRISPR loci of the host during a phage challenge, conferring specific resistance against the virus. Moreover, it has been demonstrated that such interference is based on small RNAs carrying a spacer. These RNAs would guide the defence apparatus to foreign molecules carrying sequences that match the spacers. Despite this essential role, the spacer uptake mechanism has not been addressed. A first step forward came from the detection of motifs associated with spacer precursors (proto-spacers) of Streptococcus thermophilus, revealing a specific recognition of donor sequences in this species. Here we show that the conservation of proto-spacer adjacent motifs (PAMs) is a common theme for the most diverse CRISPR systems. The PAM sequence depends on the CRISPR-CAS variant, implying that there is a CRISPR-type-specific (motif-directed) choice of the spacers, which subsequently determines the interference target. PAMs also direct the orientation of spacers in the repeat arrays. Remarkably, observations based on such polarity argue against a recognition of the spacer precursors on transcript RNA molecules as a general rule.
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Polamraju, Praveen, Alexander F. Bagley, Tyler Williamson, X. Ronald Zhu, and Steven J. Frank. "Hydrogel Spacer Reduces Rectal Dose during Proton Therapy for Prostate Cancer: A Dosimetric Analysis." International Journal of Particle Therapy 5, no. 4 (March 1, 2019): 23–31. http://dx.doi.org/10.14338/ijpt-18-00041.1.
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Abstract Purpose: Proton therapy for prostate cancer may reduce bowel dose and risk of bowel symptoms relative to photon-based methods. Here, we determined the effect of using a biodegradable, injectable hydrogel spacer on rectal dose on plans for treating prostate cancer with intensity-modulated proton therapy (IMPT) or passive scattering proton therapy (PSPT). Materials and Methods: Pairs of IMPT and PSPT plans for 9 patients were created from fused computed tomography/magnetic resonance imaging scans obtained before and after spacer injection. Calculated values of rectal V40, V60, V70, V80, and maximum dose (Dmax) were compared with Wilcoxon signed rank tests. Displacements at the base (BP), midgland (MP), and apex (AP) of the prostate relative to the anterior rectal wall with the spacer in place were averaged for each patient and correlated with V70 by using linear regression models. Results: The presence of a spacer reduced all dosimetric parameters for both PSPT and IMPT, with the greatest difference in V70, which was 81.1% lower for PSPT-with-spacer than for IMPT-without-spacer. Median displacements at BP, MP, and AP were 12 mm (range 7-19), 2 mm (range 0-4), and 1 mm (range 0-5) without the spacer and 19 mm (range 12-23), 10 mm (range 8-16), and 7 mm (range 2-12) with the spacer. Modest linear trends were noted between rectal V70 and displacement for IMPT-with-spacer and PSPT-with-spacer. When displacement was ≥8 mm, V70 was ≤5.1% for IMPT-with-spacer and PSPT-with-spacer. Conclusion: Use of biodegradable hydrogel spacers for prostate cancer treatment provides a significant reduction of radiation dose to the rectum with proton therapy. Significant reductions in rectal dose occurred in both PSPT and IMPT plans, with the greatest reduction for IMPT-with-spacer relative to PSPT alone. Prospective studies are ongoing to assess the clinical impact of reducing rectal dose with hydrogel spacers.
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Prabhakar, Attiguppe Ramasetty, Kratika Dixit, and OS Raju. "Microbiologic Evaluation of Cotton and Polytetrafluoroethylene (PTFE) Tape as Endodontic Spacer Materials in Primary Molars An in Vivo Study." Journal of Clinical Pediatric Dentistry 42, no. 1 (January 1, 2018): 21–26. http://dx.doi.org/10.17796/1053-4628-42.1.4.
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Objective: PTFE tape, which is commonly used as plumber's tape is an inorganic, non-fibrous, ribbon like material. The aim of this study was to evaluate PTFE tape as endodontic spacer material and to compare it with commonly used spacer material that is cotton, in primary teeth. Study Design: Seventeen children undergoing pulpectomy of lower second primary molar bilaterally were included in the study. Cotton and PTFE tape were placed as spacers on each side randomly. Samples were taken from the access cavity at baseline and after seven days to check for microbial leakage. Spacer materials were also checked for microbial contamination. Results: The results revealed that there was a significant increase in the bacterial colony count after seven days in cotton group. The access cavities were also positive for microbial leakage in the cotton group where the spacers showed positive growth. In PTFE group only two samples showed microbial contamination of spacer and out of two only one sample showed contamination of access cavity along with spacer. Conclusion: Within the limitations of this study, it can be concluded that PTFE tape performed better than cotton as endodontic spacer material. Thus, PTFE tape can be recommended as an endodontic spacer material as an alternative to cotton in primary teeth.
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Zhai, Bao Gai, and Yuan Ming Huang. "Synthesis of Small Silicate Spacers for Ferroelectric Liquid Crystal Displays." Key Engineering Materials 428-429 (January 2010): 383–86. http://dx.doi.org/10.4028/www.scientific.net/kem.428-429.383.
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In the presence of the aqueous solution of ammonia, tetraethyl orthosilicate (TEOS) was hydrolyzed in the mixture of ethyl alcohol and water with the results of silica spacers. The spacer morphology and size distribution of the synthesized silica spacers were characterized with scanning electron microcopy and laser light scattering spectroscopy, respectively. Our results demonstrated that the synthesized silica spacers were monodispersed and were in perfect spherical shape with their sizes of about 0.7 m in diameter. The correlation between the spacer sizes and the amount of ammonia catalyst was examined, and the spacer sizes of the silica spacers strongly depended on the temperature of chemical reaction and the amount of catalyst. The diameter of silica spacers could be well controlled by controlling the amount of ammonia catalyst, and uniformly distributed silica spacers were produced. Behavior of the miscibility of the silica spacers with a nematic liquid crystal was examined.
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Lopatina, Anna, Sofia Medvedeva, Daria Artamonova, Matvey Kolesnik, Vasily Sitnik, Yaroslav Ispolatov, and Konstantin Severinov. "Natural diversity of CRISPR spacers of Thermus : evidence of local spacer acquisition and global spacer exchange." Philosophical Transactions of the Royal Society B: Biological Sciences 374, no. 1772 (March 25, 2019): 20180092. http://dx.doi.org/10.1098/rstb.2018.0092.
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We investigated the diversity of CRISPR spacers of Thermus communities from two locations in Italy, two in Chile and one location in Russia. Among the five sampling sites, a total of more than 7200 unique spacers belonging to different CRISPR-Cas systems types and subtypes were identified. Most of these spacers are not found in CRISPR arrays of sequenced Thermus strains. Comparison of spacer sets revealed that samples within the same area (separated by few to hundreds of metres) have similar spacer sets, which appear to be largely stable at least over the course of several years. While at further distances (hundreds of kilometres and more) the similarity of spacer sets is decreased, there are still multiple common spacers in Thermus communities from different continents. The common spacers can be reconstructed in identical or similar CRISPR arrays, excluding their independent appearance and suggesting an extensive migration of thermophilic bacteria over long distances. Several new Thermus phages were isolated in the sampling sites. Mapping of spacers to bacteriophage sequences revealed examples of local acquisition of spacers from some phages and distinct patterns of targeting of phage genomes by different CRISPR-Cas systems. This article is part of a discussion meeting issue ‘The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems’.
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Harvey, S., and C. W. Hill. "Exchange of spacer regions between rRNA operons in Escherichia coli." Genetics 125, no. 4 (August 1, 1990): 683–90. http://dx.doi.org/10.1093/genetics/125.4.683.
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Abstract The Escherichia coli rRNA operons each have one of two types of spacer separating the 16S and 23S coding regions. The spacers of four operons encode tRNA(Glu2) and the other three encode both tRNA(Ile) and tRNA(Ala1B). We have prepared a series of mutants in which the spacer region of a particular rrn operon has been replaced by the opposite type. Included among these were a mutant retaining only a single copy of the tRNA(Glu2) spacer (at rrnG) and another retaining only a single copy of the tRNA(Ile)-tRNA(Ala1B) spacer (at rrnA). While both mutants grew more slowly than controls, the mutant deficient in tRNA(Glu2) spacers was more severely affected. At a frequency of 6 X 10(-5), these mutants phenotypically reverted to faster growing types by increasing the copy number of the deficient spacer. In most of these phenotypic revertants, the deficient spacer type appeared in a rrn operon which previously contained the surplus type, bringing the ratio of spacer types closer to normal. In a few cases, these spacer changes were accompanied by an inversion of the chromosomal material between the donor and recipient rrn operons. Two examples of inversion of one-half of the E. coli chromosome between rrnG and rrnH were observed. The correlation of spacer change with inversion indicated that, in these particular cases, the change was due to an intrachromatid gene conversion event accompanied by a reciprocal crossover rather than reciprocal exchange between sister chromatids.
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Cancilla, Nunzio, Alessandro Tamburini, Antonino Tarantino, Salvatore Visconti, and Michele Ciofalo. "Friction and Heat Transfer in Membrane Distillation Channels: An Experimental Study on Conventional and Novel Spacers." Membranes 12, no. 11 (October 22, 2022): 1029. http://dx.doi.org/10.3390/membranes12111029.
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The results of an experimental investigation on pressure drop and heat transfer in spacer-filled plane channels, which are representative of Membrane Distillation units, are presented and discussed. Local and mean heat transfer coefficients were obtained by using Thermochromic Liquid Crystals and Digital Image Processing. The performances of a novel spacer geometry, consisting of spheres that are connected by cylindrical rods, and are hereafter named spheres spacers, were compared with those of more conventional woven and overlapped spacers at equal values of the Reynolds number Re (in the range ~150 to ~2500), the pitch-to-channel height ratio, the flow attack angle and the thermal boundary conditions (two-side heat transfer). For any flow rate, the novel spacer geometry provided the least friction coefficient and a mean Nusselt number intermediate between those of the overlapped and the woven spacers. For any pressure drop and for any pumping power, the novel spacer provided the highest mean Nusselt number over the whole Reynolds number range that was investigated. The influence of buoyancy was also assessed for the case of the horizontal channels. Under the experimental conditions (channel height H ≈ 1 cm, ΔT ≈ 10 °C), it was found to be large in empty (spacer-less) channels that were up to Re ≈ 1200 (corresponding to a Richardson number Ri of ~0.1), but it was much smaller and limited to the range Re < ~500 (Ri < ~0.5) in the spacer-filled channels.
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Genestet, Charlotte, Yannick Baffert, Maxime Vallée, Albin Bernard, Yvonne Benito, Gérard Lina, Elisabeth Hodille, and Oana Dumitrescu. "Development, Evaluation, and Implementation of a House-Made Targeted Next-Generation Sequencing Spoligotyping in a French Laboratory." International Journal of Molecular Sciences 23, no. 19 (September 25, 2022): 11302. http://dx.doi.org/10.3390/ijms231911302.
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Epidemiological studies investigating transmission chains of tuberculosis are undertaken worldwide to tackle its spread. CRISPR locus diversity, called spoligotyping, is a widely used genotyping assay for Mycobacterium tuberculosis complex (MTBC) characterization. Herein, we developed a house-made targeted next-generation sequencing (tNGS) spoligotyping, and compared its outputs with those of membrane-based spoligotyping. A total of 144 clinical MTBC strains were retrospectively selected to be representative of the local epidemiology. Data analysis of a training set allowed for the setting of “presence”/“absence” thresholds for each spacer to maximize the sensibility and specificity related to the membrane-based spoligotyping. The thresholds above, in which the spacer was considered present, were 50 read per millions for spacers 10 and 14, 20,000 for spacers 20, 21, and 31, and 1000 for the other spacers. The confirmation of these thresholds was performed using a validation set. The overall agreement on the training and validation sets was 97.5% and 93.8%, respectively. The discrepancies concerned six strains: Two for spacer 14, two for spacer 31, and two for spacer 32. The tNGS spoligotyping, whose thresholds were finely-tuned during a careful bioinformatics pipeline development process, appears be a technique that is reliable, inexpensive, free of handling errors, and automatable through automatic transfer into the laboratory computer system.
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Lin, Qing Hai, Yuan Xi Yao, and Lian Bo Tian. "Research on Sag and Phase-Phase Space Change by Installing Interphase Spacers for Transmission Lines." Applied Mechanics and Materials 268-270 (December 2012): 1274–78. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.1274.
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Installation of inter-phase spacer can effectively protects against line fault caused by conductor galloping, non-synchronous swing and sleet jump etc large amplitude vibration, but sag of the conductor is changed if inter-phase spacer is installed. And installation of initial inter-phase spacer will cause change of inter-phase distance, which cause difficulty of successive installation. The empirical equation can’t accurately analyze change of the inter-phase distance caused during installation of the inter-phase spacer. In this paper, accurate conductor installation inter-phase spacer analysis model is established with non-linear finite element method. Change of the conductor sag after installation of the inter-phase spacer is calculated, and influence on inter-phase distance caused by different installation sequence is analyzed. The research result provides effective analysis method for length control of actual line installed inter-phase spacers, and ensures manufacturing and successful installation of the inter-phase spacer.
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Guo, Mengxue, Weifeng Lü, Ziqiang Xie, Mengjie Zhao, Weijie Wei, and Ying Han. "Effects of Symmetric and Asymmetric Double-Layer Spacers on a Negative-Capacitance Nanosheet Field-Effect Transistor." Journal of Nanoelectronics and Optoelectronics 17, no. 6 (June 1, 2022): 873–82. http://dx.doi.org/10.1166/jno.2022.3266.
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The effect of three double-layer spacers (corner/selective/dual) on the performance of a negative-capacitance nanosheet field-effect transistor (NC-NSFET) was investigated for the first time. Sentaurus technology computer-aided design simulations revealed that the NC-NSFET with corner spacer will be significantly improved in transfer and high frequency characteristics due to the increase of ferroelectric layer thickness, and the NC-NSFET with a selective spacer structure exhibits better gate controllability. Compared with the ordinary dual-k spacer structure, the switching current ratio is doubled, and its subthreshold swing and drain-induced barrier lowering are reduced by 3.0% and 48%, respectively. In addition, by introducing a selective spacer at the source side and a corner spacer at the drain side, the NC-NSFET has a smaller intrinsic delay and exhibits better capacitance matching and stronger gate controllability than that with a symmetric spacer. For the double-layer spacer, the extension of the high-k spacer in the horizontal direction is more beneficial to the improvement of the device performance than that in the vertical direction, which provides a more comprehensive reference for the spacer application in NC-NSFET.
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Kumar, Padakanti Kiran, Bukya Balaji, and Karumuri Srinivasa Rao. "Design and analysis of asymmetrical low-k source side spacer halo doped nanowire metal oxide semiconductor field effect transistor." International Journal of Electrical and Computer Engineering (IJECE) 13, no. 3 (June 1, 2023): 3519. http://dx.doi.org/10.11591/ijece.v13i3.pp3519-3529.
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In this paper, we propose a low-k source side asymmetrical spacer halo-doped nanowire metal oxide semiconductor field effect transistor (MOSFET) design and analysis. High-k spacer materials are now being researched extensively for improving electrostatic control and suppressing short-channel effects in nanoscaled electronics. However, the high-k spacers' excessive increase in fringe capacitance degrades the dynamic circuit performance. Surprisingly, this approach achieves a significant reduction in gate capacitance by maximizing the use of high-k spacer material. Three different structures, symmetrical dual-k spacer, low-k drain side asymmetrical spacer, low-k source side asymmetrical spacer halo doped nanowire MOSFET architectures are simulated and among them low-k source side asymmetrical spacer halo doped nanowire MOSFET architecture giving lower gate capacitance. After doing 3D simulations in Silvaco technology computer-aided design (TCAD) we observed that the gate capacitance and intrinsic delay are 1.23x10<sup>-17</sup> farads and 1.11x10<sup>-12</sup> seconds respectively for low-k source side asymmetrical spacer architecture and these are less as compared to high-k spacer architecture. So, the proposed structure is highly recommended for digital applications.
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Gil, Dmitry, Ali E. Atici, Rachel L. Connolly, Shannon Hugard, Sergey Shuvaev, Keith K. Wannomae, Ebru Oral, and Orhun K. Muratoglu. "Addressing prosthetic joint infections via gentamicin-eluting UHMWPE spacer." Bone & Joint Journal 102-B, no. 6_Supple_A (June 2020): 151–57. http://dx.doi.org/10.1302/0301-620x.102b6.bjj-2019-1593.r1.
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Aims We propose a state-of-the-art temporary spacer, consisting of a cobalt-chrome (CoCr) femoral component and a gentamicin-eluting ultra-high molecular weight polyethylene (UHMWPE) tibial insert, which can provide therapeutic delivery of gentamicin, while retaining excellent mechanical properties. The proposed implant is designed to replace conventional spacers made from bone cement. Methods Gentamicin-loaded UHMWPE was prepared using phase-separated compression moulding, and its drug elution kinetics, antibacterial, mechanical, and wear properties were compared with those of conventional gentamicin-loaded bone cement. Results Gentamicin-loaded UHMWPE tibial components not only eradicated planktonic Staphylococcus aureus, but also prevented colonization of both femoral and tibial components. The proposed spacer possesses far superior mechanical and wear properties when compared with conventional bone cement spacers. Conclusion The proposed gentamicin-eluting UHMWPE spacer can provide antibacterial efficacy comparable with currently used bone cement spacers, while overcoming their drawbacks. The novel spacer proposed here has the potential to drastically reduce complications associated with currently used bone cement spacers and substantially improve patients’ quality of life during the treatment. Cite this article: Bone Joint J 2020;102-B(6 Supple A):151–157.
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Zhao, Xiang, Yu Fan, Weili Li, Dong Li, Junci Cao, and Yihuang Zhang. "Optimization of Ventilation Spacer for Direct-Drive Permanent Magnet Wind Generator." Energies 12, no. 8 (April 14, 2019): 1430. http://dx.doi.org/10.3390/en12081430.
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As the rated capacity of the Direct-Drive Permanent Magnet Wind Generator (DDPMWG) increases, the heat produced from the generator’s inner components also increases and it becomes difficult to transfer the inner heat to the ambient. The ventilation spacer has a significant influence on the heat transfer process of DDPMWG. Thus, this paper focuses on the optimization of the ventilation spacer on the thermal field of DDPMWG. Firstly, the fluid flow and heat transfer coupled numerical calculation model is established. The physical model, composed of two half-slots and one tooth of DDPMWG, is established due to the structural symmetries to save the calculations. The sources and boundary conditions for the thermal calculations are also given. Five new ventilation spacers, compared with the original one, are proposed to investigate the thermal fields. The pressure drop and temperature field are compared to find the optimized ventilation spacer for the DDPMWG. The criteria are also presented for judging the heat transfer capacity. To validate the optimized ventilation spacer, the temperature rises of the armature winding with original and optimized ventilation spacers are measured. It proves that the armature winding’s temperature rise of the optimized ventilation spacer is about 4.7 K lower than that with the original ventilation spacer.
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Takahashi, Toshiaki, Manabu Takahashi, Haruyasu Yamamoto, and Hiromasa Miura. "Biomechanical study of optimum anchorage in dome-shaped high tibial osteotomy." Journal of Orthopaedic Surgery 26, no. 3 (August 13, 2018): 230949901879240. http://dx.doi.org/10.1177/2309499018792406.
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Purpose: There has been no report to date on any biomechanical study regarding the strength of fixation at the osteotomy site in dome-shaped high tibial osteotomy (HTO). In this study, we evaluated the biomechanical strength of a spacer that we improved and determined the medial site of HTO. Methods: HTO correction angles of 15° and 20° were used in all experiments, which were performed on lower leg specimens from pigs ( n = 12). The osteotomy site was fixed by a locking plate and screws with a spacer. Compression (600 N/min until 1100 N) and extended cyclic loading (200 cycles at 1000–2000 N) were performed to compare initial displacements in HTO specimens with and without spacers. Results: The reduction ratios of displacement with and without spacers at HTO correction angles of 15° and 20° were 37% and 27%, respectively. No effect of the spacer at the correction angle of 15° was observed in the cyclic loading; however, the maximum displacement and amplitude were reduced with the spacer at the correction angle of 20°. Conclusions and clinical relevance: When the HTO correction angle is small, the effect of the spacer is uncertain. However, the spacer is effective at an HTO correction angle of 20°.
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Kong, Lingtong, Jiawei Mei, Wufei Ge, Xiansheng Jin, Xiaoxuan Chen, Xianzuo Zhang, and Chen Zhu. "Application of 3D Printing-Assisted Articulating Spacer in Two-Stage Revision Surgery for Periprosthetic Infection after Total Knee Arthroplasty: A Retrospective Observational Study." BioMed Research International 2021 (February 8, 2021): 1–12. http://dx.doi.org/10.1155/2021/3948638.
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Background. Bone cement spacers are widely used in two-stage revision surgeries for periprosthetic joint infection (PJI) after total knee arthroplasty. Current spacer design results in insufficient release of drugs; therefore, current spacers have low efficacy. In this study, we explored a set of alternative articular spacer using 3D printing technology. This novel spacer will increase effectiveness of revision surgery for PJI. Methods. The spacer was designed using CAD software and constructed on site using 3D-printed silicone mold during debridement surgery. We carried out a retrospective study among patients undergoing treatment using traditional static and new articular spacers. Infection control rate, bone loss, difficulty of revision surgery, knee joint range of motion, function evaluation, and subjective satisfaction of the patients in the two groups were compared. Results. Forty-two patients undergoing knee revision surgery between Jan 2014 and Nov 2019 were included in this study. Twenty-two patients were treated with static antibiotic cement spacers, whereas the other twenty patients were with treated with 3D printing-assisted antibiotic loaded articulating spacers. Patients in the articular group showed significantly lower bone loss on the femur site and tibial site compared with patients in the static group. In addition, patients in the articular group showed significantly less operation time, intraoperative blood loss, and improved knee function and patient overall satisfaction compared with patients in the static group. Conclusions. The 3D printing-assisted articular spacer provides satisfactory range of motion during the interim period, prevents bone loss, facilitates second-stage reimplantation and postoperative rehabilitation, and results in low reinfection and complication rates.
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Kaito, Takashi, Noboru Hosono, Takahiro Makino, Noriyoshi Kaneko, Masato Namekata, and Takeshi Fuji. "Postoperative displacement of hydroxyapatite spacers implanted during double-door laminoplasty." Journal of Neurosurgery: Spine 10, no. 6 (June 2009): 551–56. http://dx.doi.org/10.3171/2009.2.17680.
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Object Double-door laminoplasty using hydroxyapatite (HA) spacers has been widely performed for compressive cervical myelopathy and has provided good neurological outcome. Although HA spacers are used for preventing reclosure of the opened laminae, they are often displaced or dislocated from their original position. The authors investigated the incidence and patterns of postoperative HA spacer displacement to determine the reasons for this unfavorable event. Methods Eighty-six patients with compressive myelopathy underwent double-door laminoplasty in which a total of 278 HA spacers were used. The displacement of HA spacers and opened laminae were assessed using postoperative lateral radiographs and CT scans. Results Postoperative dorsal migration > 2 mm was found in 116 (42%) of 278 implanted HA spacers. In addition, 33 (38%) of 86 HA spacers rotated > 10° and 29 (34%) of the 86 opened laminae tilted > 10°. Moreover, deformation of the newly formed spinal canal was observed in 51 (59%) of 86 cases, and bone fusion between the HA spacer and spinous process was achieved in only 15 (8.7%) of 172 cases. Neurological worsening and neck pain, however, were not associated with displacement of HA spacers or deformation of the spinal canal. Conclusions In double-door laminoplasty, postoperative displacement of the HA spacer with deformation of the enlarged spinal canal occurred frequently. Hydroxyapatite spacers tend to become displaced after surgery. Placing the HA spacer at the base of the spinous process close to the dura mater may prevent postoperative displacement.
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Dou, Yingying, Lin Chen, Hui Li, Biao Tang, Alex Henzen, and Guofu Zhou. "Photolithography Fabricated Spacer Arrays Offering Mechanical Strengthening and Oil Motion Control in Electrowetting Displays." Sensors 20, no. 2 (January 15, 2020): 494. http://dx.doi.org/10.3390/s20020494.
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Introducing spacers into pixelated electrowetting displays (EWDs) normally gives mechanical strengthening, while bringing undesired disturbance of water/oil interfacial dynamics. Hence, spacer array is a key pixel structure needs careful consideration in the design and fabrication of electrowetting displays. Here, we propose a spacer array, which is designed standing on the junction of adjacent pixel walls, fabricated by photolithography. The spacer array provides mechanical strength enhancement and reliable oil motion controllability. By optimizing the spacer distribution density, the EWD device may achieve 28% increase in open ratio (white area fraction) and withstand 60 N/mm2 pressure. This design of spacer array reasonably solves the contradiction between mechanical strength enhancement and optoelectronic performance in EWDs, providing potential applications in oil–water two-phase microfluidic devices.
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Ito, Manabu, Yoshihisa Kotani, Yoshihiro Hojo, Kuniyoshi Abumi, Tsuyoshi Kadosawa, and Akio Minami. "Evaluation of hydroxyapatite ceramic vertebral spacers with different porosities and their binding capability to the vertebral body: an experimental study in sheep." Journal of Neurosurgery: Spine 6, no. 5 (May 2007): 431–37. http://dx.doi.org/10.3171/spi.2007.6.5.431.
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Object The aim of this study was to evaluate the degree of bone ingrowth and bonding stiffness at the surface of hydroxyapatite ceramic (HAC) spacers with different porosities in an animal model and to discuss the ideal porous characteristics of these spacers for anterior spinal reconstruction. Methods Twenty-one adult sheep (age 1–2 years, mean weight 70 kg) were used in this experiment. Surgery consisted of anterior lumbar interbody fusion at L2–3 and L4–5, insertion of an HAC spacer (10 × 13 × 24 mm) with three different porosities (0, 3, and 15%), and single-rod anterior instrumentation. At 4 and 6 months postoperatively, the lumbar spines were harvested. Bonding conditions at the bone–HAC spacer interface were evaluated using neuroimages and biomechanically. A histological evaluation was also conducted to examine the state of bone ingrowth at the surface of the HAC spacer. Biomechanical testing showed that the bonding strength of HAC at 6 months postoperatively was 0.047 MPa in 0% porosity spacers, 0.39 MPa in 3%, and 0.49 MPa in 15% porosity spacers. The histological study showed that there was a soft-tissue layer at the surface of the HAC spacer with 0% porosity. Direct bonding was observed between bone and spacers with 3 or 15% porosity. Micro–computed tomography scans showed direct bonding between the bone and HAC with 3 or 15% porosity. No direct bonding was observed in HAC with 0% porosity. Conclusions Dense (0%) HAC anterior vertebral spacers did not achieve direct bonding to the bone in the sheep model. The HAC vertebral spacers with 3 or 15% porosity showed proof of direct bonding to the bone at 6 months postoperatively. The higher porosity HAC spacer showed better bonding stiffness to the bone.
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Erne, Holger C., Daniel Schmauß, Michael Cerny, Verena Schmauss, Denis Ehrl, Steffen Löw, and Stefan Deiler. "Resektionsarthroplastik nach Lundborg vs. Pyrocarbon-Spacer (Pyrocardan®) bei fortgeschrittener Rhizarthrose – Eine Zwei-Center-Studie." Handchirurgie · Mikrochirurgie · Plastische Chirurgie 49, no. 03 (August 2017): 175–80. http://dx.doi.org/10.1055/s-0043-115220.
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Zusammenfassung Hintergrund Ziel dieser Studie an zwei Zentren war es, die Ergebnisse nach konventioneller Resektionsarthroplastik nach Lundborg mit der Implantation des Pyrocardan®-Spacers zu vergleichen. Patienten und Methoden Bei symptomatischer Rhizarthrose im Stadium III / IV nach Eaton und Littler wurde bei 12 Patienten eine Resektionsarthroplastik nach Lundborg durchgeführt (Zentrum 1) und bei 8 Patienten ein Pyrocardan®-Spacers implantiert (Zentrum 2). Beiden Gruppen waren bezüglich des Durchschnittsalters, des präoperativen Schmerzniveaus, des radiologischen Schweregrads der Arthrose nach Eaton-Littler und der Anamnesedauer bis zur Operation vergleichbar. Die Patientendaten wurden retrospektiv erhoben und eine Nachuntersuchung nach mehr als 18 Monaten postoperativ durchgeführt, bei der der DASH-Score, das Intervall bis zur Beschwerdefreiheit, das Schmerzniveau, die Griffkraft, die Pinchkraft und die Zufriedenheit mit der Behandlung erhoben wurden. Ergebnisse Beide Gruppen verzeichnen einen ähnlichen Nachbeobachtungszeitraum von 23,6 Monaten (Resektions-Gruppe) vs. 26,1Monaten (Spacer-Gruppe). Die Schnitt-Naht-Zeit betrug für die Resektions-Gruppe 31 min und für die Spacer-Gruppe 29 min. Der mittlere DASH betrug in der Resektions-Gruppe 21,9 und in der Spacer-Gruppe 18,3. Die VAS-Schmerzintensität betrug zum Nachuntersuchungszeitraum für die Spacer-Gruppe 1,5 und für die Resektions-Gruppe 1,0. Das zeitliche Intervall bis zur Beschwerdefreiheit war mit durchschnittlich 3,7 Monaten in der Spacer-Gruppe signifikant kürzer als in der Resektions-Gruppe 5,7. Die Griffkraft und Pinchkraft waren zwischen beiden Gruppen nicht signifikant unterschiedlich. Die Zufriedenheit mit der Behandlung wurde in der Resektions-Gruppe mit durchschnittlich 9,3angegeben, in der Spacer-Gruppe mit 7,4. Schlussfolgerung Im Beobachtungsintervall von jeweils über 1,5 Jahren führten beide Techniken zu einer zufriedenstellenden Gebrauchsfähigkeit und deutlich reduzierten Beschwerdesymptomatik der operierten Hand. Die Implantation des Pyrocardan®-Spacers scheint im Vergleich zur Resektionsarthroplastik leichte Vorteile bezüglich eines kürzeren Zeitraums bis zur kompletten Ausheilung zu haben. Auf der anderen Seite stehen die Materialkosten des Spacers von mehreren Hundert Euro, die bei einer konventionellen Resektionsarthroplastik nicht anfallen.
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Hammerich, Kristoff, Jens Pollack, Alexander F. Hasse, André El Saman, René Huber, Markus Rupp, Volker Alt, Raimund W. Kinne, and Joerg Mika. "The Inverse Spacer—A Novel, Safe, and Cost-Effective Approach in Routine Procedures for Revision Knee Arthroplasty." Journal of Clinical Medicine 10, no. 5 (March 2, 2021): 971. http://dx.doi.org/10.3390/jcm10050971.
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Background: A major disadvantage of current spacers for two-stage revision total knee arthroplasty (R-TKA) is the risk of (sub-) luxation during mobilization in the prosthesis-free interval, limiting their clinical success with detrimental consequences for the patient. The present study introduces a novel inverse spacer, which prevents major complications, such as spacer (sub-) luxations and/or fractures of spacer or bone. Methods: The hand-made inverse spacer consisted of convex tibial and concave femoral components of polymethylmethacrylate bone cement and was intra-operatively molded under maximum longitudinal tension in 5° flexion and 5° valgus position. Both components were equipped with a stem for rotational stability. This spacer was implanted during an R-TKA in 110 knees with diagnosed or suspected periprosthetic infection. Postoperative therapy included a straight leg brace and physiotherapist-guided, crutch-supported mobilization with full sole contact. X-rays were taken before and after prosthesis removal and re-implantation. Results: None of the patients experienced (sub-) luxations/fractures of the spacer, periprosthetic fractures, or soft tissue compromise requiring reoperation. All patients were successfully re-implanted after a prosthesis-free interval of 8 weeks, except for three patients requiring an early exchange of the spacer due to persisting infection. In these cases, the prosthetic-free interval was prolonged for one week. Conclusion: The inverse spacer in conjunction with our routine procedure is a safe and cost-effective alternative to other articulating or static spacers, and allows crutch-supported sole contact mobilization without major post-operative complications. Maximum longitudinal intra-operative tension in 5° flexion and 5° valgus position appears crucial for the success of surgery.
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Baleani, M., F. Traina, and A. Toni. "The mechanical behaviour of a pre-formed hip spacer." HIP International 13, no. 3 (July 2003): 159–62. http://dx.doi.org/10.1177/112070000301300306.
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This study investigated the mechanical behaviour under dynamic load of a preformed hip spacer made of antibiotic impregnated bone cement (Spacer G 60, Tecres SpA, Sommacampagna VR, Italy) used in two-stage treatment of infected hip prostheses. In the experimental protocol the spacer was assumed as a temporary hip hemiarthroplasty so was liable to the same level of load stresses. Therefore, the cycling loading procedure was defined following the recommendation of the ISO 7206/4:1989 standard for determination of fatigue performance of hip stems. Three spacers were subjected to a 4 Hz cyclic load ranging between 300 and 2300 N until specimen failure or for 0.5 million cycles. This loading condition was chosen to simulate six months of patient use without any restriction in moving or loading the operated hip, which should represent the worst load history conditions for the device. One out of the three spacers completed the test. The remaining two spacers failed at 0.40 and 0.45 million cycles. These results demonstrated that the investigated spacer has finite fatigue strength when subjected to the described loading conditions but failure occurs only at the end of a very extreme loading history, hardly ever reproduced in standard clinical practice. Since decreasing the load level increases the fatigue life, the surgeons can safely implant the spacer if the patient is allowed partial weightbearing, as it is in standard clinical practice.
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Kwon, Ji-Won, Hwan-Mo Lee, Tae-Hyun Park, Sung Jae Lee, Young-Woo Kwon, Seong-Hwan Moon, and Byung Ho Lee. "Biomechanical Analysis of Allograft Spacer Failure as a Function of Cortical-Cancellous Ratio in Anterior Cervical Discectomy/Fusion: Allograft Spacer Alone Model." Applied Sciences 10, no. 18 (September 15, 2020): 6413. http://dx.doi.org/10.3390/app10186413.
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The design and ratio of the cortico-cancellous composition of allograft spacers are associated with graft-related problems, including subsidence and allograft spacer failure. Methods: The study analyzed stress distribution and risk of subsidence according to three types (cortical only, cortical cancellous, cortical lateral walls with a cancellous center bone) and three lengths (11, 12, 14 mm) of allograft spacers under the condition of hybrid motion control, including flexion, extension, axial rotation, and lateral bending,. A detailed finite element model of a previously validated, three-dimensional, intact C3–7 segment, with C5–6 segmental fusion using allograft spacers without fixation, was used in the present study. Findings: Among the three types of cervical allograft spacers evaluated, cortical lateral walls with a cancellous center bone exhibited the highest stress on the cortical bone of spacers, as well as the endplate around the posterior margin of the spacers. The likelihood of allograft spacer failure was highest for 14 mm spacers composed of cortical lateral walls with a cancellous center bone upon flexion (PVMS, 270.0 MPa; 250.2%) and extension (PVMS: 371.40 MPa, 344.2%). The likelihood of allograft spacer subsidence was also highest for the same spacers upon flexion (PVMS, 4.58 MPa; 28.1%) and extension (PVMS: 12.71 MPa, 78.0%). Conclusion: Cervical spacers with a smaller cortical component and of longer length can be risk factors for allograft spacer failure and subsidence, especially in flexion and extension. However, further study of additional fixation methods, such as anterior plates/screws and posterior screws, in an actual clinical setting is necessary.
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Ono, Atsushi, Toru Yokoyama, Takuya Numasawa, Kanichiro Wada, and Satoshi Toh. "Dural damage due to a loosened hydroxyapatite intraspinous spacer after spinous process–splitting laminoplasty." Journal of Neurosurgery: Spine 7, no. 2 (August 2007): 230–35. http://dx.doi.org/10.3171/spi-07/08/230.
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✓Excellent results from laminoplasty for cervical spinal myelopathy have been reported in many studies. Nevertheless, C-5 nerve root palsy or axial pain such as neck and shoulder pain after laminoplasty are known postoperative complications. To the authors' knowledge, dural damage from dislocation of the hydroxyapatite intraspinous spacer due to absorption of the tip of the spinous process has not been reported. Two cases of dural damage from dislocation of the hydroxyapatite intraspinous spacer after laminoplasty are described. Radiographs, computed tomography myelography, and magnetic resonance (MR) imaging revealed the dislocation of the hydroxyapatite intraspinous spacer, the absorption of the tip of the spinous process, and dural sac compression due to the hydroxyapatite intraspinous spacer. In one patient, the MR imaging studies revealed liquorrhea around the hydroxyapatite intraspinous spacers. Both patients underwent removal of the hydroxyapatite intraspinous spacer and attained good neurological recovery. In patients with dislocation of the hydroxyapatite intraspinous spacer associated with absorption of the tip of the spinous process after spinous process–splitting laminoplasty, each case should be evaluated for aggravating symptoms of myelopathy, dural damage, and liquorrhea around the spacer.
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Chang, Yuhan, Mel S. Lee, Jiann-Jong Liau, Yu-Liang Liu, Wen-Chuan Chen, and Steve W. N. Ueng. "Polyethylene-Based Knee Spacer for Infection Control: Design Concept and Pre-Clinical In Vitro Validations." Polymers 12, no. 10 (October 13, 2020): 2334. http://dx.doi.org/10.3390/polym12102334.
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Antibiotic-loaded polymethyl methacrylate (PMMA) has been widely applied in the treatment of knee periprosthetic joint infections. However, problems with antibiotic-loaded PMMA-based spacers, such as structural fracture and implant dislocation, remain unresolved. A novel polyethylene-based spacer, designed with an ultra-congruent articulating surface and multiple fenestrations, was introduced in the current study. Validation tests for biomechanical safety, wear performance, and efficacy of antibiotic cement were reported. During cycle fatigue testing, no tibial spacer failures were observed, and less wear debris generation was reported compared to commercial PMMA-based spacers. The volumetric wear of the novel spacer was within the safety threshold for osteolysis-free volumetric wear. An effective infection control was demonstrated despite the application of lesser antibiotic cement in the 30-day antibiotic elution test. The tube dilution test confirmed adequate inhibitory capabilities against pathogens with the loaded antibiotic option utilized in the current study. The novel polyethylene-based knee spacer may offer sufficient biomechanical safety and serve as an adequate carrier of antibiotic-loaded cement for infection control. Further clinical trials shall be conducted for more comprehensive validation of the novel spacer for practical application.
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Li, Haoluan, Nabila Zebouchi, Manu Haddad, Alistair Reid, and Egbert Ekkel. "Development of Future Compact and Eco-Friendly HVDC Gas Insulated Systems: Test Verification of Shape-Optimized DC Spacer Models." Energies 15, no. 22 (November 16, 2022): 8563. http://dx.doi.org/10.3390/en15228563.
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Spacers for the HVDC GIS/GIL play an important role in mechanically supporting conductors and separating compartments. At the same time, their insulation performance affects the stability and safety of system operation. Design rules and knowledge specific to AC spacers do not apply to those of DC spacers. Considering the shape influence on the surface electric field intensity of the spacer under HVDC applied voltage, as determined in our previous work, an optimized shape of a spacer model based on finite element electric field calculations and using standard HVAC alumina filled epoxy material and two novel types of materials were studied. The simulation’s results show that the DC shape optimization of the spacers can effectively reduce the electric field magnitudes along the spacer under different temperature gradients. To verify practically these findings, this paper presents the reduced scale gas insulated prototype that was constructed, the optimized DC spacers that were fabricated and the DC testing results using SF6-free surrounding gas: C4-Perfluoronitrile (C4-PFN, 3MTM NovecTM 4710)/CO2 and Trifluoroiodomethane (CF3I)/CO2. The results show that the shape-optimized spacer models made of conventional HVAC filled epoxy material have successfully passed the tests up to the maximum applicable ±123 kV DC exceeding thus ±119 kV DC that corresponds to the nominal voltage ±500 kV DC of the full scale.
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Kanemura, Aritetsu, Minoru Doita, Tetsuhiro Iguchi, Koichi Kasahara, Masahiro Kurosaka, and Masatoshi Sumi. "Delayed dural laceration by hydroxyapatite spacer causing tetraparesis following double-door laminoplasty." Journal of Neurosurgery: Spine 8, no. 2 (February 2008): 121–28. http://dx.doi.org/10.3171/spi/2008/8/2/121.
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Object The authors describe 4 cases of delayed dural laceration by hydroxyapatite (HA) spacer causing tetra-paresis following double-door laminoplasty. There are few reports of iatrogenic spinal cord lesions developing after double-door laminoplasty, although some complications such as postoperative C-5 paralysis or axial symptoms have been reported. The purpose of this report is to draw attention to the possibility of delayed dural laceration and its triggering mechanism. Methods One hundred thirty patients treated for cervical myelopathy were followed up for an average of 2 years and 9 months after laminoplasty. Results Four patients experienced aggravation of cervical myelopathy. Anterior dislodgement of HA spacers was shown on plain lateral radiographs. Follow-up T2-weighted magnetic resonance imaging demonstrated that the dislodged HA spacers were surrounded by cerebrospinal fluid at the time of aggravation. The dislodged HA spacers were removed and the dural membrane defects were repaired by patching with the fascia of the gluteus maximus muscle. The preoperative symptoms improved after the second operation in all patients. Conclusions It is hypothesized that the loosening of the HA spacer in split spinous processes could occur with the movement of the cervical spine and/or the breakage of the suture before bone bonding. Anterior dislodgement of the HA spacer toward the spinal canal would cause dural laceration by direct friction between the dural membrane and the dislodged HA spacer, resulting in clinical aggravation. Despite the well-documented advantages of using HA spacers for double-door laminoplasty, possible laceration due to a dislodged HA spacer should be considered as a late complication.
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Kawai, Risa, Maiko Niki, Shiho Yada, and Tomokazu Yoshimura. "Surface Adsorption Properties and Layer Structures of Homogeneous Polyoxyethylene-Type Nonionic Surfactants in Quaternary-Ammonium-Salt-Type Amphiphilic Gemini Ionic Liquids with Oxygen- or Nitrogen-Containing Spacers." Molecules 25, no. 21 (October 22, 2020): 4881. http://dx.doi.org/10.3390/molecules25214881.
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The amphiphilic ionic liquids containing an alkyl chain in molecules form nano-structure in the bulk, although they also show surface activity and form aggregates in aqueous solutions. Although insights into the layer structures of ionic liquids were obtained using X-ray and neutron scattering techniques, the nanostructures of ionic liquids remain unclear. Herein, the surface adsorption and bulk properties of homogeneous polyoxyethylene (EO)-type nonionic surfactants (CxEO6; x = 8, 12, or 16) were elucidated in quaternary-ammonium-salt-type amphiphilic gemini ionic liquids with oxygen or nitrogen-containing spacers [2Cn(Spacer) NTf2; (Spacer) = (2-O-2), (2-O-2-O-2), (2-N-2), (2/2-N-2), (3), (5), or (6); n = 10, 12, or 14 for (2-O-2) and n = 12 for all other spacers] by surface tension, small- and wide-angle X-ray scattering, cryogenic transmission electron microscopy, and viscosity measurements. The surface tension of C12EO6 in 2Cn(Spacer) NTf2 with oxygen-containing spacers increased with increasing concentration of C12EO6, becoming close to that of C12EO6 alone, indicating that the amphiphilic ionic liquid adsorbed at the interface was replaced with CxEO6. In contrast, both 2Cn(Spacer) NTf2 with nitrogen-containing spacers and nonionic surfactants remained adsorbed at the interface at high concentrations. In the bulk, it was found that 2Cn(Spacer) NTf2 formed layer structures, in which the spacing depended on the alkyl chain length of CxEO6. These insights are expected to advance the practical applications of amphiphilic ionic liquids such as ion permeation, drug solubilization, and energy delivery systems.
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Kuhns, Craig A., Jonathan A. Harris, Mir M. Hussain, Aditya Muzumdar, Brandon S. Bucklen, and Saif Khalil. "Evaluation of Two Novel Integrated Stand-Alone Spacer Designs Compared with Anterior and Anterior-Posterior Single-Level Lumbar Fusion Techniques: An <italic>In Vitro</italic> Biomechanical Investigation." Asian Spine Journal 11, no. 6 (December 31, 2017): 854–62. http://dx.doi.org/10.4184/asj.2017.11.6.854.
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<sec><title>Study Design</title><p><italic>In vitro</italic> biomechanical investigation.</p></sec><sec><title>Purpose</title><p>To compare the biomechanics of integrated three-screw and four-screw anterior interbody spacer devices and traditional techniques for treatment of degenerative disc disease.</p></sec><sec><title>Overview of Literature</title><p>Biomechanical literature describes investigations of operative techniques and integrated devices with four dual-stacked, diverging interbody screws; four alternating, converging screws through a polyether-ether-ketone (PEEK) spacer; and four converging screws threaded within the PEEK spacer. Conflicting reports on the stability of stand-alone devices and the influence of device design on biomechanics warrant investigation.</p></sec><sec><title>Methods</title><p>Fourteen cadaveric lumbar spines were divided randomly into two equal groups (n=7). Each spine was tested intact, after discectomy (injured), and with PEEK interbody spacer alone (S), anterior lumbar plate and spacer (AP+S), bilateral pedicle screws and spacer (BPS+S), circumferential fixation with spacer and anterior lumbar plate supplemented with BPS, and three-screw (SA3s) or four-screw (SA4s) integrated spacers. Constructs were tested in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Researchers performed one-way analysis of variance and independent <italic>t</italic>-testing (<italic>p</italic>≤0.05).</p></sec><sec><title>Results</title><p>Instrumented constructs showed significantly decreased motion compared with intact except the spacer-alone construct in FE and AR (<italic>p</italic>≤0.05). SA3s showed significantly decreased range of motion (ROM) compared with AP+S in LB (<italic>p</italic>≤0.05) and comparable ROM in FE and AR. The three-screw design increased stability in FE and LB with no significant differences between integrated spacers or between integrated spacers and BPS+S in all loading modes.</p></sec><sec><title>Conclusions</title><p>Integrated spacers provided fixation statistically equivalent to traditional techniques. Comparison of three-screw and four-screw integrated anterior lumbar interbody fusion spacers revealed no significant differences, but the longer, larger-diameter interbody spacer with three-screw design increased stabilization in FE and LB; the diverging four-screw design showed marginal improvement during AR.</p></sec>
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Achigar, Rodrigo, Martina Scarrone, Geneviève M. Rousseau, Cécile Philippe, Felipe Machado, Valentina Duvós, María Pía Campot, et al. "Ectopic Spacer Acquisition in Streptococcus thermophilus CRISPR3 Array." Microorganisms 9, no. 3 (March 1, 2021): 512. http://dx.doi.org/10.3390/microorganisms9030512.
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Streptococcus thermophilus relies heavily on two type II-A CRISPR-Cas systems, CRISPR1 and CRISPR3, to resist siphophage infections. One hallmark of these systems is the integration of a new spacer at the 5′ end of the CRISPR arrays following phage infection. However, we have previously shown that ectopic acquisition of spacers can occur within the CRISPR1 array. Here, we present evidence of the acquisition of new spacers within the array of CRISPR3 of S. thermophilus. The analysis of randomly selected bacteriophage-insensitive mutants of the strain Uy01 obtained after phage infection, as well as the comparison with other S. thermophilus strains with similar CRISPR3 content, showed that a specific spacer within the array could be responsible for misguiding the adaptation complex. These results also indicate that while the vast majority of new spacers are added at the 5′ end of the CRISPR array, ectopic spacer acquisition is a common feature of both CRISPR1 and CRISPR3 systems in S. thermophilus, and it can still provide phage resistance. Ectopic spacer acquisition also appears to have occurred naturally in some strains of Streptococcus pyogenes, suggesting that it is a general phenomenon, at least in type II-A systems.
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Anagnostakos, Konstantinos. "Therapeutic Use of Antibiotic-loaded Bone Cement in the Treatment of Hip and Knee Joint Infections." Journal of Bone and Joint Infection 2, no. 1 (January 1, 2017): 29–37. http://dx.doi.org/10.7150/jbji.16067.
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Abstract. The use of antibiotic-loaded cement spacers is an established method in the management of periprosthetic hip and knee joint infections. Despite inconsistencies among published studies, data shows that infection control rates exceed 90% with two-stage exchange arthroplasty. The present work reviews the current literature about antibiotic-loaded cement spacers and concentrates on the indications for spacer implantation, spacer production details, antibiotic impregnation, pharmacokinetic properties, clinical success, mechanical complications, and systemic safety.
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Wang, Yonghong, Bing Xiao, Guizhong Qiu, Lipeng Bi, Keqiang Xu, Chongqing Jiao, and Shuyun Cao. "Extraction of Equivalent Circuit Parameter of the GIS Pipe Spacer." E3S Web of Conferences 185 (2020): 01014. http://dx.doi.org/10.1051/e3sconf/202018501014.
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In Gas Insulated Switchgear (GIS) substation, the spacer used for supporting conductor, isolating air chamber and insulation is a very important insulation component in GIS pipe, and it is important to study the spacer to ensure the insulation performance and quality of GIS. Local distortion of electric field distribution will be produced when electromagnetic wave propagates to spacers. In this article, the static capacitance calculated by electromagnetic simulation is used to model spacers.
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Williams, Scott M., Glenn R. Furnier, Eric Fuog, and Curtis Strobeck. "Evolution of the Ribosomal DNA Spacers of Drosophila melanogaster: Different Patterns of Variation on X and Y Chromosomes." Genetics 116, no. 2 (June 1, 1987): 225–32. http://dx.doi.org/10.1093/genetics/116.2.225.
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ABSTRACT Length variation of the ribosomal gene spacers of Drosophila melanogaster was studied. Analysis of 47 X chromosomal and 47 Y chromosomal linked rDNA arrays collected from five continents indicates that the arrays on the two chromosomes differ qualitatively. The Y-linked arrays from around the world share little or no similarity for either their overall length or the organization of their spacers. Most of the X-linked arrays do, however, share a major length spacer of 5.1 kb. In addition, those X-linked arrays that have a major 5.1-kb band have similar spacer organization as demonstrated by genomic DNA digestions with several restriction enzymes. These data strongly support the hypothesis that spacer length patterns on only X-linked genes are maintained primarily by natural selection.
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Sathe, Manisha, Shruti Srivastava, Sumit Agrawal, and Ramrao Ghorpade. "Effect of Spacer and the Enzyme-Linked Immunosorbent Assay." Defence Science Journal 66, no. 5 (September 30, 2016): 471. http://dx.doi.org/10.14429/dsj.66.10700.
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The effect of spacers and the enzyme-linked immunosorbent assay (ELISA) formats on the functional parameters of assays such as lower detection limit, inhibitory concentration at 50 per cent (IC50), and specificity were studied. Enzyme conjugates having hydrophobic and hydrophilic spacers were prepared using O-isopropyl methylphosphonic acid (IMPA) and horseradish peroxidase (HRP) as an enzyme label. Comparison was made with reference to enzyme conjugate without any spacer. The present investigation revealed that the presence of a hydrophilic spacer in the enzyme conjugate significantly improves the sensitivity of assays. An enhanced IC50 value achieved was 0.01 μg mL−1 for free antigen detection by direct immunoassay using hydrophilic spacers and precoating of ELISA plates by secondary antibody. The use of a hydrophilic spacer might have helped in projecting the hapten in the aqueous phase, leading to enhanced antibody binding signal and improved sensitivity of the assay.
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Kwon, Anthony J., William D. Hunter, Mark Moldavsky, Kanaan Salloum, and Brandon Bucklen. "Indirect decompression and vertebral body endplate strength after lateral interbody spacer impaction: cadaveric and foam-block models." Journal of Neurosurgery: Spine 24, no. 5 (May 2016): 727–33. http://dx.doi.org/10.3171/2015.10.spine15450.
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OBJECTIVE The lateral transpsoas approach to the lumbar spine is a well-defined procedure for the management of discogenic spinal pathology necessitating surgical intervention. Intervertebral device subsidence is a postoperative clinical risk that can lead to recurrence of symptomatic pathology and the need for surgical reintervention. The current study was designed to investigate static versus expandable lateral intervertebral spacers in indirect decompression for preserving vertebral body endplate strength. METHODS Using a cadaveric biomechanical study and a foam-block vertebral body model, researchers compared vertebral body endplate strength and distraction potential. Fourteen lumbar motion segments (7 L2–3 and 7 L4–5 specimens) were distributed evenly between static and expandable spacer groups. In each specimen discectomy was followed by trialing and spacer impaction. Motion segments were axially sectioned through the disc, and a metal stamp was used to apply a compressive load to superior and inferior vertebral bodies to quantify endplate strength. A paired, 2-sample for means t-test was performed to determine statistically significant differences between groups (p ≤ 0.05). A foam-block endplate model was used to control simulated disc tension when a spacer with 2- and 3-mm desired distraction was inserted. One-way ANOVA and a post hoc Student Newman-Keuls test were performed (p ≤ 0.05) to determine differences in distraction. RESULTS Both static and expandable spacers restored intact neural foramen and disc heights after device implantation (p > 0.05). Maximum peak loads at endplate failure for static and expandable spacers were 1764 N (± 966 N) and 2284 N (± 949 N), respectively (p ≤ 0.05). The expandable spacer consistently produced greater desired distraction than was created by the static spacer in the foam-block model (p ≤ 0.05). Distraction created by fully expanding the spacer was significantly greater than the predetermined goals of 2 mm and 3 mm (p ≤ 0.05). CONCLUSIONS The current investigation shows that increased trialing required for a static spacer may lead to additional iatrogenic endplate damage, resulting in less distraction and increased propensity for postoperative implant subsidence secondary to endplate disruption.
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Sano, Yoshihiko, Kosuke Fukagawa, and Fujio Kuwahara. "Numerical Estimation of Limiting Current Density by Focusing on Mass Transfer within Porous Spacers in an Electro-Dialysis." Membranes 9, no. 7 (June 28, 2019): 75. http://dx.doi.org/10.3390/membranes9070075.
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Estimating and increasing limiting current density (LCD) levels is of fundamental importance for the development of electrodialysis (ED) systems, and it is becoming clear that the use of porous spacers can significantly increase such LCD levels. In this study, a three-dimensional numerical simulation was proposed for evaluating the mass transfer within a porous spacer unit cell and for estimating LCD levels. It was found that our proposed method is effective for estimating the minimum value of an LCD, which is a significant factor related to the safe operation of ED systems. Furthermore, it was found that increasing the minimum effective Sherwood number provides a key to increasing LCD levels. Porous spacer design guidelines were proposed based on the numerical simulation results, after which a new spacer was introduced, designed according to those guidelines. It was found that flow disturbances on the membrane caused by porous spacer structures can lead to increases in effective Sherwood numbers and that LCD levels could be increased by eliminating the flow stagnation behind the structures on the membrane. The LCD of our new spacer was found to be higher than that of the spacers with the highest LCD levels in use at present. Therefore, we can conclude that the proposed design guidelines are effective for increasing LCD levels.
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Aviram, Naama, Ashley N. Thornal, David Zeevi, and Luciano A. Marraffini. "Different modes of spacer acquisition by the Staphylococcus epidermidis type III-A CRISPR-Cas system." Nucleic Acids Research 50, no. 3 (January 20, 2022): 1661–72. http://dx.doi.org/10.1093/nar/gkab1299.
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Abstract CRISPR-Cas systems provide prokaryotic organisms with an adaptive defense mechanism that acquires immunological memories of infections. This is accomplished by integration of short fragments from the genome of invaders such as phages and plasmids, called ‘spacers’, into the CRISPR locus of the host. Depending on their genetic composition, CRISPR-Cas systems can be classified into six types, I-VI, however spacer acquisition has been extensively studied only in type I and II systems. Here, we used an inducible spacer acquisition assay to study this process in the type III-A CRISPR-Cas system of Staphylococcus epidermidis, in the absence of phage selection. Similarly to type I and II spacer acquisition, this type III system uses Cas1 and Cas2 to preferentially integrate spacers from the chromosomal terminus and free dsDNA ends produced after DNA breaks, in a manner that is enhanced by the AddAB DNA repair complex. Surprisingly, a different mode of spacer acquisition from rRNA and tRNA loci, which spans only the transcribed sequences of these genes and is not enhanced by AddAB, was also detected. Therefore, our findings reveal both common mechanistic principles that may be conserved in all CRISPR-Cas systems, as well as unique and intriguing features of type III spacer acquisition.
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Seymour, Zachary A., Stephanie Daignault, Walter Bosch, Hiram Alberto Gay, Jeff M. Michalski, Daniel A. Hamstra, and Michael Pinkawa. "Long-term follow-up after radiotherapy for prostate cancer with and without rectal hydrogel spacer: A pooled prospective evaluation of quality of life." Journal of Clinical Oncology 37, no. 7_suppl (March 1, 2019): 39. http://dx.doi.org/10.1200/jco.2019.37.7_suppl.39.
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39 Background: Hydrogel spacers are a tool to improve dosimetry and overall quality of life with limited follow-up in men receiving radiotherapy for prostate cancer. This present study is a pooled analysis of a prospective cohorts with long-term follow-up quality of life (QOL) data with or without hydrogel spacers to minimize dose adjacent organs at risk. Methods: QOL was examined using the Expanded Prostate Cancer Index Composite (EPIC) to compare mean changes from baseline. A total of 215 patients from a randomized multi-institutional trial of radiation with or without hydrogel spacer with a QOL end-point were pooled with 165 non-randomized patients from a single institution with prospective QOL collection in both patients with or without hydrogel spacer. The proportions of men with minimally important differences (MIDs) relative to pre-treatment baseline in each domain were tested using repeated measures logistic models with pre-specified thresholds for clinically significant decline. Results: A total of 380 men were evaluated (64% with spacer and 36% without) with QOL data being available for 199 men beyond 24 months of follow-up (median: 39.5 months, range: 31-71.4 mo). Treatment with spacer was associated with less decline in average long-term bowel QOL (89.4 for control and 94.7 for experimental) with differences at > 2 years meeting the threshold of MID difference between cohorts (Bowel Score Difference from baseline: control = -5.1 spacer = 0.3 Diff = -5.4 p = 0.0003). When evaluated over time men without spacer were more likely to have 1xMID (5 points) declines in bowel QOL (p = 0.01). At long-term follow-up 1xMID was 36% without spacer vs 14% with spacer (p = 0.0006 OR = 3.5) while 2x MID was seen in 19% vs 6% (p = 0.008 OR = 3.6). The use of spacer was associated with improved bowel frequency (p = 0.002), reduced bleeding (p = 0.005) and less overall bowel problems (p = 0.007). Conclusions: In this pooled analysis of QOL after prostate radiotherapy with up to 5-years of follow-up utilization of a hydrogel spacer was associated with preservation of bowel QOL. This QOL benefit was preserved with long-term follow-up.
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Nazififard, Mohammad. "Computational fluid dynamic simulation of swirl flow in hexagonal rod bundle geometry by split mixing vane grid spacers." Thermal Science 23, no. 5 Part B (2019): 3143–52. http://dx.doi.org/10.2298/tsci171006076n.
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Heat transfer and pressure drop are numerically investigated for turbulent flows through a hexagonal fuel rod bundle. For the purpose of numerical analysis, the geometric and boundary conditions were taken from the VVER-1000. Since VVER-1000 does not have mixing vane on the grid spacer of the fuel assembly, split mixing vane is designed to boost turbulent flow and heat transfer in the rod bundle subchannels. The computational domain including two grid spacers extend from 100 ? Dh upstream of the first grid spacer to 250 ? Dh downstream of the second grid spacer. The steady-state form of the RANS, mass, energy and turbulence equations was discretized and solved using ANSYS-CFX. The standard k-? model is employed to simulate turbulence. The results show a considerable increase in the average heat transfer to ~10 ? Dh downstream of the grid spacer using the mixing vane on the grid spacer of VVER type reactor. As expected, the pressure loss through the grid spacer also increased slightly with the mixing vanes.