bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparison Between Porous NiTi and Ti-6Al-4V Fixation Hardware on Bone Remodeling After a Reconstruction Surgery
Authors: Raad Bahram , Shayesteh Moghaddam Narges , Elahinia Mohammad 
Published: September 2016

The aim of this article is to investigate the effect of two different fixation hardware materials on bone remodeling after a mandibular reconstruction surgery and to restore the mandible’s function, healthy appearance, mastication, swallowing, breathing, and speech. The hypothesis is that using fixation hardware with stiffness close to that of the surrounding bone will result in a more successful healing process in the mandible bone.
The finite element model includes the material properties and forces of the cancellous bone, cortical bone, ligaments, muscles, and teeth. The reconstruction surgery is modeled by including the fixation hardware and the grafted bone. In the sectioned mandible, to best mimic the geometry of the mandible, two single barrel grafts are placed at the top of each other to form a double barrel graft set. Two different materials were used as the mandibular fixation parts, stiff Ti-6Al-4V, and porous superelastic Nickel-Titanium (NiTi) alloys.
A comparison of these two alloys demonstrates that using porous NiTi alloy as the fixation part results in a faster healing pace. Furthermore, the density distribution in the mandibular bone after the healing process is more similar to the normal mandible density distribution.
The simulations results indicate that the porous superelastic NiTi fixation hardware transfers and distributes the existing forces on the mandible bone more favorably. The probability of stress shielding and/or stress concentration decrease. This type of fixation hardware, therefore, is more appropriate for mandible bone reconstruction surgery.
Effect of Reprocessing on the Rheological, Electrical and Mechanical Properties of Polypropylene/Carbon Nanotube Composites
Authors: Stan Felicia , Sandu Laurentiu Ionut , Fetecau Catalin , Rosculet Razvan Train 
Published: September 2016

In the near future, carbon nanotubes containing plastic parts are likely to enter the environment in large quantities and, due to their resistance to degradation, the environmental impact may be even more important than that of similarly shaped plastic products. Thus, there is an immediate need to examine and understand the effect of recycling on the properties of polymer/carbon nanotube composites in order to develop sustainable recycling technologies.
In this paper, polypropylene filled with different levels of multi-walled carbon nanotubes (MWCNTs) manufactured by injection molding was closed-loop recycled in order to investigate the effect of recycling and reprocessing on its rheological, electrical and mechanical properties. Preliminary results show that the PP/MWCNT composites keep the flow performance after mechanical recycling. Moreover, the stress and strain at break increase after one reprocessing cycle (mechanical recycling coupled with injection molding) whereas no statistically significant changes in electrical conductivity, Young modulus and tensile strength of the PP/MWCNT composites filled with 1, 3 and 5 wt.% were observed.
Investigating a Die Quench Cracking Problem in 52100 Steel Bearing Rings With Computer Simulation
Authors: Reardon Arthur C. , Freborg Andrew , Li Zhichao (Charlie) , Ferguson Lynn 
Published: September 2016

Quenching using a press with controlled die loads, commonly referred to as press quenching, is a specialized technique used to minimize distortion of critical components such as gears and high quality bearing races. Improper press load magnitudes or timing of the load application may restrict part movement during quenching to the point of imposing stresses that cause cracking, especially in a common bearing steel such as AISI 52100, high carbon, high strength steel. This paper applies a finite element based heat treat simulation tool, DANTE®, to investigate the sensitivity of cracking to press quenching process parameters.
The typical method for designing a press quench process to control flatness, out-of-round, and taper is by experience coupled with trial-and-error. This is accomplished by adjusting oil flow rates, flow directions, die loads, and the timing of die loads. Metallurgical phase transformations occur during the quenching process as austenite transforms to martensite and possibly to diffusive phases. Thermal contraction due to cooling and volumetric expansion due to the phase changes therefore occur simultaneously during the heat treating process. A constantly changing stress state is present in the part, and improperly applied die loads, oil flow or oil flow rate can add additional stress to result in cracking.
An inconsistent cracking problem in an AISI 52100 bearing ring was evaluated using production trials, but the process statistics were not conclusive in identifying the source of the problem. Heat treatment process modeling using DANTE was used to investigate the effects of quench rate, die load pulsing, and several other process variables to determine how these parameters impact the resulting stresses generated during the press quenching operation.
Polishing Characteristics of Transparent Polycrystalline YAG Ceramics Using Magnetic Field-Assisted Finishing
Authors: Ross Daniel , Wang Yanming , Ramadhan Hadyan , Yamaguchi Hitomi 
Published: September 2016

Transparent polycrystalline yttrium aluminum garnet (YAG) ceramics have garnered an increased level of interest for high-power laser applications due to their ability to be manufactured in large sizes, and doped in relatively substantial concentrations when compared to traditional single-crystalline gain media. However, surface characteristics have a direct effect on the lasing ability of these materials, and a lack of a fundamental understanding of the polishing mechanisms of these ceramics remains a challenge for their utilization. The aim of this paper is to study the polishing characteristics of YAG ceramics using magnetic field-assisted finishing (MAF). An experimental setup was developed, through the refinement of the MAF process, for YAG ceramic workpieces. Using this equipment with diamond abrasives, the YAG ceramic surfaces were polished to sub-nanometer scale. Polishing trials with fine diamond abrasive and colloidal silica were then performed on this sub-nanometer surface and the material removal mechanisms were analyzed.
Polishing with 0–0.1 μm diameter diamond abrasive caused increasing roughness with polishing time due to the continuous cycle of relatively substantial chipping followed by minor smoothing. Polishing with colloidal silica caused valleys to widen with increased polishing time and the grain structure of the ceramic influenced the material removal.
Springback Induced in Single Point Incrementally Formed 2024-T3 Aluminum of Various Thicknesses
Authors: Neveux Trey C. , Roth John T. , Ragai Ihab 
Published: September 2016

Incremental forming (IF) is sheet metal process proving to be of particular interest in industry as a method to create complex geometries. The technology offers the flexibility to create complex geometry on drafted profiles without the necessity of a forming die, which offers unique advantages over die forming processes, including: significantly reduced lead time, eliminating initial die costs and the need to retain the die after the products life cycle is complete, which can be significant, and the ability to modify the geometry with relative ease throughout the product’s life cycle.
During incremental forming, the material’s local plastic deformation induces high residual stresses into the workpiece, causing significant springback once it is released from the clamping fixture used to hold the workpiece stationary during forming. Different material thicknesses result in different degrees of springback on the workpiece. This is due in part to the change in section modulus of the formed part. Thicker materials will have a larger section modulus and therefore not be if two different material thicknesses undergo equal deformation, the thinner material will experience greater elastic recovery, or springback.
If incremental forming is to ever reach industry level applications, the material’s springback behavior at a variety of thicknesses must be characterized. Having the knowledge of the resulting springback is necessary for further research to be conducted on incremental forming in order to reduce or eliminate springback. Also, it is important for designers and engineers to design products within the capabilities of the technique.
This paper investigates the springback present in 5 thicknesses of 2024-T3 clad aluminum subsequent to incremental forming and release from the forming fixture.
It is found that as material sheet thickness increases and the specimens are formed to the same internal geometries, springback after releasing from the clamping fixture decreases, and variation in springback between equal thicknesses decreases.
Effects of Tool Deflection in Accumulated Double-Sided Incremental Forming Regarding Part Geometry
Authors: Ren Huaqing , Moser Newell , Zhang Zixuan , Ehmann Kornel F. , Cao Jian 
Published: September 2016

Incremental forming is a flexible dieless forming process. In incremental forming, the metal sheet is clamped around its periphery. One or multiple generic stylus-type tools move along a predefined toolpath, incrementally deforming the sheet metal into a final, freeform shape. Compared with the traditional sheet metal forming process, the incremental forming process is more flexible, energy efficient and cost effective due to lower capital investment related to tooling. However, maintaining tight geometric tolerances in incremental formed parts can be a challenge. Specifically, undesired global bending is usually induced near the region between the tools and fixture resulting in a compromise in geometric accuracy.
To address this issue, Accumulated Double-Sided Incremental Forming (ADSIF) is proposed, which utilizes two tools on both sides of the metal to better achieve localized deformation while simultaneously constraining global bending outside the forming area. Moreover, in ADSIF, the two tools are moving from inward to outward, and thus the tools are always forming virgin material and so as to limit forces on the already-formed part. Thus, ADSIF has a higher potential to achieve the desired geometry. Nevertheless, tool deflection due to machine compliance is still an issue that can have a considerable effect on geometric accuracy.
In this work, the effect of tool deflection related to part geometry is studied for the ADSIF process. The nature of using two tools, rather than one, in ADSIF inherently implies that relative tool position is a critical process parameter. It is the region near these two tools where local squeezing and bending of the sheet occurs, the primary modes of deformation found in ADSIF. The change of relative tool positions (i.e., tool gap and relative position angle) are studied in detail by first developing an analytical model. It is concluded that the tool gap will be enlarged under the influence of tool compliance while the relative position angle is less affected. Additionally, a finite element simulation capable of modeling tool deflection is established. The comparison between the simulation results using rigid tools and deformable ones clearly demonstrated the significant influence of tool compliance on part geometry. Lastly, an axisymmetric part with varying wall angles was formed, and it was confirmed that ADSIF demonstrates improved geometry accuracy compared with conventional Double-Sided Incremental Forming.
An Environmental and Cost Analysis of Stamping Sheet Metal Parts
Authors: Cooper Daniel R. , Rossie Kathleen E. , Gutowski Timothy G. 
Published: September 2016

Little work has been done on quantifying the environmental impacts and costs of sheet metal stamping. In this work we present models that can be used to predict the energy requirements, global warming potential, human health impacts, and costs of making drawn parts using zinc (kirksite) die-sets and hydraulic or mechanical presses. The methodology presented can also be used to produce models of stamping using other die materials, such as iron, for which casting data already exists.
An unprecedented study on the environmental impacts and costs of zinc die-set production was conducted at a leading Michigan die-maker. This analysis was used in conjunction with electrical energy measurements on forming presses to complete cradle-to-gate impact and cost analyses on producing small batch size hood and tailgate parts. These case studies were used to inform a generalized model that allows engineers to predict the impacts and costs of forming based on as little information as the final part material, surface area, thickness and batch size (number of units produced).
The case studies show that press electricity is an insignificant contributor to the overall impacts and costs. The generalized models highlight that while costs for small batch production are dominated by the die-set, the environmental impacts are often dominated by the sheet metal. These findings explain the motivation behind research into die-less forming processes such as incremental sheet forming, and emphasize the need to minimize sheet metal scrap generation in order to reduce environmental impacts.
Antimold Prophylaxis May Reduce the Risk of Invasive Fusariosis in Hematologic Patients with Superficial Skin Lesions with Positive Culture for Fusarium
Authors: Varon Andrea G. , Nouér Simone A. , Barreiros Gloria , Trope Beatriz Moritz , Akiti Tiyomi , Nucci Marcio 
Published: September 2016

ABSTRACT

Hematologic patients with superficial skin lesions on admission growing
Fusarium
spp. are at a high risk for developing invasive fusariosis during neutropenia. We evaluated the impact of primary prophylaxis with a mold-active azole in preventing invasive fusariosis in these patients. Between August 2008 and December 2014, patients with acute leukemia or aplastic anemia and recipients of hematopoietic cell transplants were screened on admission with dermatologic and direct exams and fungal cultures of superficial skin lesions. Until November 2009, no interventions were made. Beginning in December 2009, patients with baseline skin lesions and a direct exam and/or culture suggestive of the presence of
Fusarium
spp. received prophylaxis with voriconazole or posaconazole. Skin lesions in the extremities (mostly onychomycosis and interdigital intertrigo) were present on admission in 88 of 239 episodes (36.8%); 44 lesions had hyaline septate hyphae identified by direct exam, and cultures from 11 lesions grew
Fusarium
spp. Antimold prophylaxis was given for 20 episodes (voriconazole for 17 and posaconazole for 3). Invasive fusariosis was diagnosed in 14 episodes (5.8%). Among patients with baseline skin lesions with positive cultures for
Fusarium
spp., 4 of 5 without antimold prophylaxis developed invasive fusariosis versus 0 of 6 with antimold prophylaxis (
P
= 0.01; 95% confidence interval for the difference between proportions, 22% to 96%). Primary antifungal prophylaxis with an antimold azole may prevent the occurrence of invasive fusariosis in high-risk hematologic patients with superficial skin lesions on admission growing
Fusarium
spp.
Esculentin-1a-Derived Peptides Promote Clearance of Pseudomonas aeruginosa Internalized in Bronchial Cells of Cystic Fibrosis Patients and Lung Cell Migration: Biochemical Properties and a Plausible Mode of Action
Authors: Cappiello Floriana , Di Grazia Antonio , Segev-Zarko Li-av , Scali Silvia , Ferrera Loretta , Galietta Luis , Pini Alessandro , Shai Yechiel , Di Y. Peter , Mangoni Maria Luisa 
Published: September 2016

ABSTRACT

Pseudomonas aeruginosa
is the major microorganism colonizing the respiratory epithelium in cystic fibrosis (CF) sufferers. The widespread use of available antibiotics has drastically reduced their efficacy, and antimicrobial peptides (AMPs) are a promising alternative. Among them, the frog skin-derived AMPs, i.e., Esc(1-21) and its diastereomer, Esc(1-21)-1c, have recently shown potent activity against free-living and sessile forms of
P. aeruginosa
. Importantly, this pathogen also escapes antibiotics treatment by invading airway epithelial cells. Here, we demonstrate that both AMPs kill
Pseudomonas
once internalized into bronchial cells which express either the functional or the ΔF508 mutant of the CF transmembrane conductance regulator. A higher efficacy is displayed by Esc(1-21)-1c (90% killing at 15 μM in 1 h). We also show the peptides' ability to stimulate migration of these cells and restore the induction of cell migration that is inhibited by
Pseudomonas
lipopolysaccharide when used at concentrations mimicking lung infection. This property of AMPs was not investigated before. Our findings suggest new therapeutics that not only eliminate bacteria but also can promote reepithelialization of the injured infected tissue. Confocal microscopy indicated that both peptides are intracellularly localized with a different distribution. Biochemical analyses highlighted that Esc(1-21)-1c is significantly more resistant than the all-
l
peptide to bacterial and human elastase, which is abundant in CF lungs. Besides proposing a plausible mechanism underlying the properties of the two AMPs, we discuss the data with regard to differences between them and suggest Esc(1-21)-1c as a candidate for the development of a new multifunctional drug against
Pseudomonas
respiratory infections.
Crystal Structure of the Pseudomonas aeruginosa BEL-1 Extended-Spectrum β-Lactamase and Its Complexes with Moxalactam and Imipenem
Authors: Pozzi Cecilia , De Luca Filomena , Benvenuti Manuela , Poirel Laurent , Nordmann Patrice , Rossolini Gian Maria , Mangani Stefano , Docquier Jean-Denis 
Published: September 2016

ABSTRACT

BEL-1 is an acquired class A extended-spectrum β-lactamase (ESBL) found in
Pseudomonas aeruginosa
clinical isolates from Belgium which is divergent from other ESBLs (maximum identity of 54% with GES-type enzymes). This enzyme is efficiently inhibited by clavulanate, imipenem, and moxalactam. Crystals of BEL-1 were obtained at pH 5.6, and the structure of native BEL-1 was determined from orthorhombic and monoclinic crystal forms at 1.60-Å and 1.48-Å resolution, respectively. By soaking native BEL-1 crystals, complexes with imipenem (monoclinic form, 1.79-Å resolution) and moxalactam (orthorhombic form, 1.85-Å resolution) were also obtained. In the acyl-enzyme complexes, imipenem and moxalactam differ by the position of the α-substituent and of the carbonyl oxygen (in or out of the oxyanion hole). More surprisingly, the Ω-loop, which includes the catalytically relevant residue Glu166, was found in different conformations in the various subunits, resulting in the Glu166 side chain being rotated out of the active site or even in displacement of its Cα atom up to approximately 10 Å. A BEL-1 variant showing the single Leu162Phe substitution (BEL-2) confers a higher level of resistance to CAZ, CTX, and FEP and shows significantly lower

K
m

values than BEL-1, especially with oxyiminocephalosporins. BEL-1 Leu162 is located at the beginning of the Ω-loop and is surrounded by Phe72, Leu139, and Leu148 (contact distances, 3.5 to 3.9 Å). This small hydrophobic cavity could not reasonably accommodate the bulkier Phe162 found in BEL-2 without altering neighboring residues or the Ω-loop itself, thus likely causing an important alteration of the enzyme kinetic properties.
Antibiofilm Activity and Synergistic Inhibition of Staphylococcus aureus Biofilms by Bactericidal Protein P128 in Combination with Antibiotics
Authors: Nair Sandhya , Desai Srividya , Poonacha Nethravathi , Vipra Aradhana , Sharma Umender 
Published: September 2016

ABSTRACT

P128 is an antistaphylococcal protein, comprising a cell wall-degrading enzymatic region and a
Staphylococcus
-specific binding region, which possesses specific and potent bactericidal activity against sensitive and drug-resistant strains of
Staphylococcus aureus
. To explore P128's ability to kill
S. aureus
in a range of environments relevant to clinical infection, we investigated the anti-
S. aureus
activity of P128 alone and in combination with standard-of-care antibiotics on planktonic and biofilm-embedded cells. P128 was found to have potent antibiofilm activity on preformed
S. aureus
biofilms as detected by CFU reduction and a colorimetric minimum biofilm inhibitory concentration (MBIC) assay. Scanning electron microscopic images of biofilms formed on the surfaces of microtiter plates and on catheters showed that P128 at low concentrations could destroy the biofilm structure and lyse the cells. When it was tested in combination with antibiotics which are known to be poor inhibitors of
S. aureus
in biofilms, such as vancomycin, gentamicin, ciprofloxacin, linezolid, and daptomycin, P128 showed highly synergistic antibiofilm activity that resulted in much reduced MBIC values for P128 and the individual antibiotics. The synergistic effect was seen for both sensitive and resistant isolates of
S. aureus
. Additionally, in an
in vitro
mixed-biofilm model mimicking the wound infection environment, P128 was able to prevent biofilm formation by virtue of its anti-
Staphylococcus
activity. The potent
S. aureus
biofilm-inhibiting activity of P128 both alone and in combination with antibiotics is an encouraging sign for the development of P128 for treatment of complicated
S. aureus
infections involving biofilms.
A Novel Genome-Editing Platform for Drug-Resistant Acinetobacter baumannii Reveals an AdeR-Unrelated Tigecycline Resistance Mechanism
Authors: Trebosc Vincent , Gartenmann Sarah , Royet Kevin , Manfredi Pablo , Tötzl Marcus , Schellhorn Birgit , Pieren Michel , Tigges Marcel , Lociuro Sergio , Sennhenn Peter C. , Gitzinger Marc , Bumann Dirk , Kemmer Christian 
Published: September 2016

ABSTRACT

Infections with the Gram-negative coccobacillus
Acinetobacter baumannii
are a major threat in hospital settings. The progressing emergence of multidrug-resistant clinical strains significantly reduces the treatment options for clinicians to fight
A. baumannii
infections. The current lack of robust methods to genetically manipulate drug-resistant
A. baumannii
isolates impedes research on resistance and virulence mechanisms in clinically relevant strains. In this study, we developed a highly efficient and versatile genome-editing platform enabling the markerless modification of the genome of
A. baumannii
clinical and laboratory strains, regardless of their resistance profiles. We applied this method for the deletion of AdeR, a transcription factor that regulates the expression of the AdeABC efflux pump in tigecycline-resistant
A. baumannii
, to evaluate its function as a putative drug target. Loss of
adeR
reduced the MIC
90
of tigecycline from 25 μg/ml in the parental strains to 3.1 μg/ml in the Δ
adeR
mutants, indicating its importance in the drug resistance phenotype. However, 60% of the clinical isolates remained nonsusceptible to tigecycline after
adeR
deletion. Evolution of artificial tigecycline resistance in two strains followed by whole-genome sequencing revealed loss-of-function mutations in
trm
, suggesting its role in an alternative AdeABC-independent tigecycline resistance mechanism. This finding was strengthened by the confirmation of
trm
disruption in the majority of the tigecycline-resistant clinical isolates. This study highlights the development and application of a powerful genome-editing platform for
A. baumannii
enabling future research on drug resistance and virulence pathways in clinically relevant strains.