The demand for high temperature-resistant superalloys such as Inconel 718 is increasing rapidly, as they possess superior mechanical, chemical, and physical properties. Hence, these materials are ...highly adaptable for aerospace, nuclear, and marine applications. Nonetheless, during machining of such alloys, high temperatures develop at the interface region. It accelerates the tool wear and adversely affects the integrity of the prepared surfaces. Although conventional metalworking fluids are competent in normalizing/limiting the cutting-edge temperature, the environmental obligations and health issues to the workers have forced the manufacturing industry to move towards environment-friendly machining process, viz. dry machining. High-speed machining of Inconel 718 (under dry condition) can lead to the attainment of high cutting temperatures, thereby activating the mechanisms of built-up-edge (BUE) development and diffusion, leading to enhanced wear rate of tool. Besides, high temperatures can alter the integrity, infuse residual stresses, and promote crack generation/propagation on the processed surface. Therefore, the present paper contributes a detailed insight into heat generation during machining of Inconel 718 and its influence on various machining responses. Additionally, the work addresses multiple possibilities to reduce the cutting temperature with due emphasis on distinct machining methodologies, viz. dry, wet, and tool texturing.
Abbreviations: BUE: Built-up Edge; AISI: American Iron and Steel Institute; AJM: Abrasive Jet Machining; AlTiN: Aluminium Titanium Nitride; Al
2
O
3
: Aluminum Oxide or Alumina; Al
2
O
3
/SiC: SiC whisker-reinforced alumina Al
2
O
3
ceramic; Al
2
O
3
-TiC: TiC added alumina ceramic; AS: Conventional tool; AT-PA: Parallel grooves; AT-PE: Perpendicular grooves; AT-W: Wavy pattern; CaF
2
: Calcium fluoride; CBN: Cubic boron nitride; CBN-OR: Perpendicular to cutting edge; CBN-ORE : Perpendicular grooves 30 µm away from main cutting edge; CBN-PA: Parallel to cutting edge; CFT: Nano textured tool; CFT WS: Nano textured with soft coated WS
2
; CrN: Chromium Nitride; CT: Conventional cutting tool; DOC notch wear: Depth-of-cut notch wear; EBSD: Electron back scatter diffraction; ECM: Electrochemical machining; FCC: Face centered cubic; GWP: Global warming potential; HPC: High-pressure cooling; HPJ: High-pressure jet; HPJA: High-pressure jet assistance; HRSA: Heat-resisted super alloy; HSS: High-speed steel; IPF: Inverse pole figure; ISO: International organization for standardization; l/h: liter/hour; L/min: Liter/minute; Micro-EDM: Micro-electrical machining; MoS
2
: Molybdenum disulfide; MQL: Minimum quantity lubrication; MWFs: Metal-working fluids; NIOSH: National Institute of Occupational Safety and Health; PCBN: Polycrystalline Cubic Boron Nitride; PVD: Physical vapor deposition; SEM: Scanning electron microscope; Si
3
N
4
: Silicon nitride; ST: Graphite soft-coated tool; STT-F: Linear grooves on the flank surface; STT-R: Elliptical textures on the rake face; STT-0: Plain WC/Co carbide tool; STT-1: Elliptical grooves; STT-2: Parallel grooves; STT-3: Perpendicular grooves; TiAlN: Titanium Aluminium Nitride; TiCN: Titanium Carbonitride; TiN: Titanium Nitride; T-IPA: Perpendicular textures to chip flow; T-IPE: Parallel textures to the chip flow; T-PA: Texture surfaces inclined an angle to the chip flow; TT: Textured tool under dry condition; TT+SL: Textured tool under solid lubricant-assisted MQL cooling conditions; T1: Un-textured tool; T2: Texture tool having circular pit holes; T3: Hybrid texture tool combination of circular pit holes and linear grooves; TT: Textured inserts; TT: WS
2
-soft-coated WS
2
textured tool; T1: Conventional insert; T2: Conical dimple-textured tool; T3: Square dimple-shaped insert; T4: Scratches provided on the cutting insert; T-1: Untextured insert; T-2: Pit holes textured insert; T-3: Hybrid textured insert; US: United States; USM: Ultrasonic Machining; WC: Tungsten carbide; WC-Co: Tungsten carbide-cobalt; WEDM: Wire electrical discharge machining; WS
2
: Tungsten disulfide
Enterococcus faecium is a commensal but also a bacteremia causing pathogen, which is inherently resistant to several antimicrobials and has a great ability to acquire new traits. Bacterial membrane ...vesicles (MVs) are increasingly recognized as a mode of cell-free communication and a way to deliver virulence factors and/or antimicrobial resistance determinants. These features make MVs interesting research targets in research on critical hospital pathogens. This study describes for the first time that E. faecium strains produce MVs. It presents a morphological as well as a proteomic analysis of MVs isolated from four different, clinically relevant E. faecium strains grown under two different conditions and identifies MV-associated proteins in all of them. Interestingly, 11 virulence factors are found among the MV-associated proteins, including biofilm-promoting proteins and extracellular matrix-binding proteins, which may aid in enterococcal colonization. Additionally, 11 antimicrobial resistance-related proteins were MV-associated. Among those, all proteins encoded by the vanA-cluster of a vancomycin resistant strain were found to be MV-associated. This implies that E. faecium MVs may be utilized by the bacterium to release proteins promoting virulence, pathogenicity and antimicrobial resistance.
Enterococcal infections, especially bacteremia and endocarditis, are challenging to treat because E. faecium have acquired resistance to multiple classes of antimicrobials, including ampicillin, aminoglycosides, and glycopeptides. Thus, research on different modes of enterococcal pathogenicity is warranted. This study utilized a proteomic approach to identify MV-associated proteins of different nosocomial E. faecium strains representing four clinically relevant sequence types (STs), namely ST17, ST18, ST78, and ST192. The presented data suggest that E. faecium MVs are involved in virulence and antimicrobial resistance.
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•Nosocomial E. faecium produces MVs.•MVs contain proteins of different cellular origin.•Virulence factors and antimicrobial resistance related proteins can be MV-associated.
This study highlights the use of low-cost agro-industrial raw material – date molasses for fermentative production of biosurfactants. Date palm (Phoenix dactylifera L.) is the primary crop in Oman, ...which shares 82% of all fruit crops production in the country. When date molasses was used as the sole carbon and energy source for biosurfactant production using Bacillus subtilis B20, a product yield of 2.29 ± 0.38 g/l was obtained. The biosurfactant reduced surface tension and interfacial tension from 60 to 25 mN/m to 27 and 5.02 mN/m respectively. It also showed significant stability under a wide range of temperatures, pH and salt concentrations. Additional 9.7% oil was recovered through core-flood studies, accessing the potential of biosurfactant to enhance oil recovery under reservoir conditions. Current studies showed date molasses could be suitable for use in the production of biosurfactant and it has the potential for use in enhancing oil recovery.
► Date molasses was used for biosurfactant production by Bacillus subtilis B20. ► The produced biosurfactant reduced surface tension and interfacial tension. ► The biosurfactant had significant stability under oil reservoir conditions. ► Core-flood studies using biosurfactant showed 9.7% extra residual oil recovery.
ABSTRACT
The K2 eclipsing binary (EB) candidates EPIC 211982753 (hereinafter called EPIC2753) and EPIC 211915147 (hereinafter called EPIC5147) are characterized with the help of photometric and ...high-resolution spectroscopic data. The light curve analysis uses the Rc-band photometric data from the 1.3-m Devasthal Fast Optical Telescope (DFOT, India), ASAS-3, and K2 observations. High-resolution échelle spectra are collected using the HERMES spectrograph at the 1.2-m MERCATOR telescope (La Palma, Spain). The synthetic light and radial velocity curves are generated with the help of the modeling package phoebe 1.0. The orbital period analysis based on the ∼3.2 yr of K2 observations does not show any change in the orbital period of both targets. The component masses M1, 2 are estimated as 1.69(0.02) and 1.59(0.02) M⊙ for EPIC2753, and 1.48(0.01) and 1.27(0.01) M⊙ for EPIC5147. Both systems are high mass-ratio EBs with q>0.85. The component radii R1, 2 are found to be 1.66(0.02) and 1.53(0.02) R⊙ for EPIC2753, and 1.80(0.05) and 1.42(0.05) R⊙ for EPIC5147. The distances of EPIC2753 and EPIC5147 are determined as 238(4) and 199(5) pc, respectively. MESA Isochrones and Stellar Tracks are used to understand the evolutionary status of both systems.
Electronic resources have changed surgical education in the 21st century. Resources spanning from digital textbooks to multiple choice question banks, online society meetings, and social media can ...facilitate surgical education. The COVID pandemic drastically changed the paradigm for education. The ramifications of Zoom lectures and online surgical society meetings will last into the future. Educators and learners can be empowered by the many available electronic resources to enhance surgical training and education.
With broadening indications, more options for hematopoietic cell transplantation (HCT) and improvement in survival, the number of long-term HCT survivors is expected to increase steadily. Infertility ...is a frequent problem that long-term HCT survivors and their partners face and it can negatively impact on the quality of life. The most optimal time to address fertility issues is before the onset of therapy for the underlying disease; however, fertility preservation should also be addressed before HCT in all children and patients of reproductive age, with referral to a reproductive specialist for patients interested in fertility preservation. In vitro fertilization (IVF) and embryo cryopreservation, oocyte cryopreservation and ovarian tissue banking are acceptable methods for fertility preservation in adult women/pubertal females. Sperm banking is the preferred method for adult men/pubertal males. Frequent barriers to fertility preservation in HCT recipients may include the perception of lack of time to preserve fertility given an urgency to move ahead with transplant, lack of patient-physician discussion because of several factors (for example, time constraints, lack of knowledge), inadequate access to reproductive specialists, and costs and lack of insurance coverage for fertility preservation. There is a need to raise awareness in the medical community about fertility preservation in HCT recipients.
► A review of material behavior modeling of metal forming and machining is presented. ► The necessity of modeling the processes for proper design is highlighted. ► Challenging issues and future areas ...of research are identified.
Manufacturing process modeling is gaining importance in view of stiff global competition to produce the goods of specified design in an optimal way. In particular, metal forming and machining (both traditional and non-traditional) have been extensively modeled using numerical techniques. Three basic steps of modeling of manufacturing processes are analytical representation of working principle of the process, modeling of material behavior and method of solution. In this paper, a comprehensive review of various approaches of material behavior modeling has been presented. The material behavior modeling has great influence on the design of process, tools and the final product. This aspect is highlighted in the present review. Metal forming processes, traditional machining processes and non-traditional machining processes are considered for the study. Different material models are compared with respect to their suitability for the design of process, tooling and product. Finally, the paper suggests the directions for further research in this area.
Shear Assisted Processing and Extrusion (ShAPE) -a novel processing route that combines high shear and extrusion conditions- was evaluated as a processing method to densify melt spun magnesium alloy ...(AZ91E) flake materials. This study illustrates the microstructural regimes and transitions in crystallographic texture that occur as a result of applying simultaneous linear and rotational shear during extrusion. Characterization of the flake precursor and extruded tube was performed using scanning and transmission electron microscopy, x-ray diffraction and microindentation techniques. Results show a unique transition in the orientation of basal texture development. Despite the high temperatures involved during processing, uniform grain refinement and material homogenization are observed. These results forecast the ability to implement the ShAPE processing approach for a broader range of materials with novel microstructures and high performance.
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