Sustainable lubrication: low molecular weight PTFE micro-particles as extreme pressure additives for heavy duty grease applications

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
TCSM Gupta ◽  
Ajay Kumar ◽  
Babu Prasad
Keyword(s):  
Molecular Weight ◽  
High Speed ◽  
Cyclic Load ◽  
Low Molecular Weight ◽  
Extreme Pressure ◽  
Content Type ◽  
Micro Particles ◽  
Lithium Complex ◽  
Ep Additive ◽  
Lithium Complex Grease

Purpose The purpose of this paper is to formulate heavy-duty lithium complex grease using low molecular weight poly tetra fluoro ethylene (PTFE) micro-particles as extreme pressure (EP) additive manufactured by E-beam scissoring and ultra-high speed grinding process of pre-sintered PTFE scrap. Design/methodology/approach Lithium complex grease is formulated with PTFE micro-particles, and optimum treat rate was studied by standard bench tests by ASTM D 2266 and IP-239 for tribological properties and compared with commercially available Molybdenum Di sulphide (Moly)-based lithium complex grease. The performance of the grease was further evaluated by a cyclic load test at varying speeds and loads to simulate the operational field conditions. Findings The lithium complex PTFE grease was manufactured using PTFE micro-particles as EP additive. The PTFE micro-particles dispersed in the lithium complex grease significantly improve the anti-wear performance and load bearing properties. Further, when the product was tested under a cyclic load conditions on standard tribological bench test against commercially available Moly lithium complex grease, shows stable anti-wear properties and reduced coefficient of friction. Originality/value The low molecular weight PTFE micro-particles, manufactured in the in-house electron beam (E-beam) and ultra-high speed micronizer facility from a pre-sintered PTFE scrap has been used as EP additive for grease applications for the first time. The results on the cyclic load tests indicate significant performance improvement in retaining the anti-wear and friction properties. Thus, value addition is done in formulating superior performance grease and evaluating under cyclic load conditions similar to field operating conditions and also in creating value added additives by converting the pre-sintered PTFE scarp which is environmental hazard due to poor biodegradability, creating a cyclic economy and a sustainable concept.

scholarly journals Low-Molecular-Weight Metabolites Secreted by Paenibacillus larvae as Potential Virulence Factors of American Foulbrood

2014 ◽  
Vol 80 (8) ◽  
pp. 2484-2492 ◽  
Author(s):  
Hedwig-Annabell Schild ◽  
Sebastian W. Fuchs ◽  
Helge B. Bode ◽  
Bernd Grünewald
Keyword(s):  
Molecular Weight ◽  
Virulence Factors ◽  
Gene Clusters ◽  
Paenibacillus Larvae ◽  
Economic Losses ◽  
Low Molecular Weight ◽  
American Foulbrood ◽  
Toxic Activity ◽  
Content Type

ABSTRACTThe spore-forming bacteriumPaenibacillus larvaecauses a severe and highly infective bee disease, American foulbrood (AFB). Despite the large economic losses induced by AFB, the virulence factors produced byP. larvaeare as yet unknown. To identify such virulence factors, we experimentally infected young, susceptible larvae of the honeybee,Apis mellifera carnica, with differentP. larvaeisolates. Honeybee larvae were rearedin vitroin 24-well plates in the laboratory after isolation from the brood comb. We identified genotype-specific differences in the etiopathology of AFB between the tested isolates ofP. larvae, which were revealed by differences in the median lethal times. Furthermore, we confirmed that extracts ofP. larvaecultures contain low-molecular-weight compounds, which are toxic to honeybee larvae. Our data indicate thatP. larvaesecretes metabolites into the medium with a potent honeybee toxic activity pointing to a novel pathogenic factor(s) ofP. larvae. Genome mining ofP. larvaesubsp.larvaeBRL-230010 led to the identification of several biosynthesis gene clusters putatively involved in natural product biosynthesis, highlighting the potential ofP. larvaeto produce such compounds.

High-Speed Melt Spinning of Sheath-Core Bicomponent Polyester Fibers: High and Low Molecular Weight Poly(ethylene Terephthalate) Systems

1997 ◽  
Vol 67 (9) ◽  
pp. 684-694 ◽  
Author(s):  
J. Radhakrishnan ◽  
Takeshi Kikutani ◽  
Norimasa Okui
Keyword(s):  
Molecular Weight ◽  
High Speed ◽  
Melt Spinning ◽  
Ethylene Terephthalate ◽  
Maxwell Model ◽  
Low Molecular Weight ◽  
Structural Development ◽  
Solidification Temperature ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

Sheath-core bicomponent spinning of high molecular weight poly (ethylene terephthalate) (hmpet, IV = 1.02 dl/g) and low molecular weight pet (lmpet, IV = 0.65 dl/g) is done at a take-up velocity range of 1 to 7 km/min. The structures of the individual components in the as-spun bicomponent fibers are characterized. Orientation and orientation-induced crystallization of the hmpet component are enhanced, while those of the lmpet component are suppressed in comparison to corresponding single component spinning. Numerical simulation with the Newtonian model shows that elongational stress in the hmpet component is enhanced and that of the lmpet decreases during high-speed bicomponent spinning. The difference in elongational viscosity is the main factor influencing the mutual interaction between hmpet and lmpet, which in turn affect spinline dynamics, solidification temperature, and structural development in high-speed bicomponent spinning. Simulation with an upper-convected Maxwell model shows that considerable stress relaxation can occur in the lmpet component if the hmpet component solidifies before lmpet. A mechanism for structural development is also proposed, based on the simulation results and structural characterization data.

No effect of enoxaparin on outcome of aneurysmal subarachnoid hemorrhage: a randomized, double-blind, placebo-controlled clinical trial

2003 ◽  
Vol 99 (6) ◽  
pp. 953-959 ◽  
Author(s):  
Jari Siironen ◽  
Seppo Juvela ◽  
Joona Varis ◽  
Matti Porras ◽  
Kristiina Poussa ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Molecular Weight ◽  
Subarachnoid Hemorrhage ◽  
Low Molecular Weight Heparin ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Intracranial Bleeding ◽  
Low Molecular Weight ◽  
Double Blind ◽  
Content Type ◽  
Fine Print

Object. From the moment an intracranial aneurysm ruptures, cerebral blood flow is impaired, and this impairment mainly determines the outcome in patients who survive after the initial bleeding. The exact mechanism of impairment is unknown, but activation of coagulation and fibrinolysis correlate with clinical condition and outcome after aneurysmal subarachnoid hemorrhage (SAH). The purpose of this study was to determine whether enoxaparin, a low-molecular-weight heparin, which is a well-known anticoagulating agent, has any effect on the outcome of aneurysmal SAH postoperatively. Methods. In this randomized, double-blind, single-center clinical trial, 170 patients (85 per group) with aneurysmal SAH were randomly assigned to receive either enoxaparin (40 mg subcutaneously once daily) or a placebo, starting within 24 hours after occlusion of the aneurysm and continuing for 10 days. Analysis was done on an intention-to-treat basis. Outcome was assessed at 3 months on both the Glasgow Outcome and modified Rankin Scales. Patients were eligible for the study if surgery was performed within 48 hours post-SAH, and no intracerebral hemorrhage was larger than 20 mm in diameter on the first postoperative computerized tomography scan. At 3 months, there were no significant differences in outcome by treatment group. Of the 170 patients, 11 (6%) died, and only 95 (56%) had a good outcome. Principal causes of unfavorable outcome were poor initial condition, delayed cerebral ischemia, and surgical complications. There were four patients with additional intracranial bleeding in the group receiving enoxaparin. The bleeding was not necessarily associated with the treatment itself, nor did it require treatment, and there were no such patients in the placebo group. Conclusions. Enoxaparin seemed to have no effect on the outcome of aneurysmal SAH in patients who had already received routine nimodipine and who had received triple-H therapy when needed. Routine use of low-molecular-weight heparin should be avoided during the early postoperative period in patients with SAH, because this agent seems to increase intracranial bleeding complications slightly, with no beneficial effect on neurological outcome.

Spontaneous spinal subdural hematoma associated with low-molecular-weight heparin

2005 ◽  
Vol 2 (5) ◽  
pp. 612-613 ◽  
Author(s):  
Yoon-Hee Cha ◽  
John H. Chi ◽  
Nicholas M. Barbaro
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Spinal Instrumentation ◽  
Cord Compression ◽  
Low Molecular Weight ◽  
Content Type ◽  
First Case ◽  
Spinal Subdural Hematoma ◽  
History Of ◽  
Fine Print

✓ Spinal subdural hematomas (SDHs) are a rare cause of cord compression and typically occur in the setting of spinal instrumentation or coagulopathy. The authors report the first case of a spontaneous spinal SDH occurring in conjunction with low-molecular-weight heparin use in a patient with a history of spinal radiotherapy.

scholarly journals Low-Molecular-Weight Thiols and Thioredoxins Are Important Players in Hg(II) Resistance in Thermus thermophilus HB27

2017 ◽  
Vol 84 (2) ◽  
Author(s):  
J. Norambuena ◽  
Y. Wang ◽  
T. Hanson ◽  
J. M. Boyd ◽  
T. Barkay
Keyword(s):  
Heavy Metals ◽  
Molecular Weight ◽  
Thermus Thermophilus ◽  
Mercury Resistance ◽  
Low Molecular Weight ◽  
Thiol Groups ◽  
Content Type ◽  
Protein Thiols ◽  
Thioredoxin System

ABSTRACTMercury (Hg), one of the most toxic and widely distributed heavy metals, has a high affinity for thiol groups. Thiol groups reduce and sequester Hg. Therefore, low-molecular-weight (LMW) and protein thiols may be important cell components used in Hg resistance. To date, the role of low-molecular-weight thiols in Hg detoxification remains understudied. The mercury resistance (mer) operon ofThermus thermophilussuggests an evolutionary link between Hg(II) resistance and low-molecular-weight thiol metabolism. Themeroperon encodes an enzyme involved in methionine biosynthesis, Oah. Challenge with Hg(II) resulted in increased expression of genes involved in the biosynthesis of multiple low-molecular-weight thiols (cysteine, homocysteine, and bacillithiol), as well as the thioredoxin system. Phenotypic analysis of gene replacement mutants indicated that Oah contributes to Hg resistance under sulfur-limiting conditions, and strains lacking bacillithiol and/or thioredoxins are more sensitive to Hg(II) than the wild type. Growth in the presence of either a thiol-oxidizing agent or a thiol-alkylating agent increased sensitivity to Hg(II). Furthermore, exposure to 3 μM Hg(II) consumed all intracellular reduced bacillithiol and cysteine. Database searches indicate thatoah2is present in allThermussp.meroperons. The presence of a thiol-related gene was also detected in some alphaproteobacterialmeroperons, in which a glutathione reductase gene was present, supporting the role of thiols in Hg(II) detoxification. These results have led to a working model in which LMW thiols act as Hg(II)-buffering agents while Hg is reduced by MerA.IMPORTANCEThe survival of microorganisms in the presence of toxic metals is central to life's sustainability. The affinity of thiol groups for toxic heavy metals drives microbe-metal interactions and modulates metal toxicity. Mercury detoxification (mer) genes likely originated early in microbial evolution in geothermal environments. Little is known about howmersystems interact with cellular thiol systems.Thermusspp. possess a simplemeroperon in which a low-molecular-weight thiol biosynthesis gene is present, along withmerRandmerA. In this study, we present experimental evidence for the role of thiol systems in mercury resistance. Our data suggest that, inT. thermophilus, thiolated compounds may function side by side withmergenes to detoxify mercury. Thus, thiol systems function in consort withmer-mediated resistance to mercury, suggesting exciting new questions for future research.

Real-time in vivo imaging of the convective distribution of a low-molecular-weight tracer

2005 ◽  
Vol 102 (1) ◽  
pp. 90-97 ◽  
Author(s):  
David Croteau ◽  
Stuart Walbridge ◽  
Paul F. Morrison ◽  
John A. Butman ◽  
Alexander O. Vortmeyer ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Real Time ◽  
Ct Scanning ◽  
Quantitative Autoradiography ◽  
Cerebral White Matter ◽  
Low Molecular Weight ◽  
Convection Enhanced Delivery ◽  
Content Type ◽  
Fine Print

Object. Convection-enhanced delivery (CED) is increasingly used to distribute therapeutic agents to locations in the central nervous system. The optimal application of convective distribution of various agents requires the development of imaging tracers to monitor CED in vivo in real time. The authors examined the safety and utility of an iodine-based low-molecular-weight surrogate tracer for computerized tomography (CT) scanning during CED. Methods. Various volumes (total volume range 90–150 µ1) of iopamidol (MW 777 D) were delivered to the cerebral white matter of four primates (Macaca mulatta) by using CED. The distribution of this imaging tracer was determined by in vivo real-time and postinfusion CT scanning (≤ 5 days after infusion [one animal]) as well as by quantitative autoradiography (14C-sucrose [all animals] and 14C-dextran [one animal]), and compared with a mathematical model. Clinical observation (≤ 5 months) and histopathological analyses were used to evaluate the safety and toxicity of the tracer delivery. Real-time CT scanning of the tracer during infusion revealed a clearly definable region of perfusion. The volume of distribution (Vd) increased linearly (r2 = 0.97) with an increasing volume of infusion (Vi). The overall Vd/Vi ratio was 4.1 ± 0.7 (mean ± standard deviation) and the distribution of infusate was homogeneous. Quantitative autoradiography confirmed the accuracy of the imaged distribution for a small (sucrose, MW 359 D) and a large (dextran, MW 70 kD) molecule. The distribution of the infusate was identifiable up to 72 hours after infusion. There was no clinical or histopathological evidence of toxicity in any animal. Conclusions. Real-time in vivo CT scanning of CED of iopamidol appears to be safe, feasible, and suitable for monitoring convective delivery of drugs with certain features and low infusion volumes.

The role of hemolysate in the facilitation of oxyhemoglobin-induced contraction in rabbit basilar arteries

1994 ◽  
Vol 81 (2) ◽  
pp. 261-266 ◽  
Author(s):  
Toshiki Aoki ◽  
Katsunobu Takenaka ◽  
Satoshi Suzuki ◽  
Neal F. Kassell ◽  
Oren Sagher ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Contractile Response ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Equal Concentration ◽  
Content Type ◽  
Basilar Arteries ◽  
Fine Print

✓ The importance of factors within hemolysate in modulating oxyhemoglobin (oxyHb)-induced contraction was examined in an in vitro model of rabbit basilar arteries. When the basilar arteries were exposed to purified oxyHb alone, the contractile response observed was significantly weaker than that seen in arteries exposed to hemolysate containing an equal concentration of oxyHb. In order to delineate the nature of the factors within hemolysate that facilitate contraction, hemolysate was fractionated, and various components were tested individually for their ability to elicit this effect. A low-molecular-weight fraction of hemolysate, ranging from 0.5 to 2.0 kD, elicited only a mild contraction. However, when this fraction was combined with purified oxyHb, the contractile response was comparable in magnitude to that of unfractionated hemolysate. These studies confirm that purified oxyHb is capable of inducing contraction in vitro. The data also demonstrate that oxyHb elicits a significantly weaker contraction than does hemolysate. In addition, the results suggest that low-molecular-weight components in hemolysate (in the 0.5- to 2.0-kD range), while incapable of inducing a potent contraction alone, may act in concert with oxyHb to elicit the vasoconstriction seen following subarachnoid hemorrhage.

scholarly journals Plant- and Microbe-Derived Compounds Affect the Expression of Genes Encoding Antifungal Compounds in a Pseudomonad with Biocontrol Activity

2011 ◽  
Vol 77 (8) ◽  
pp. 2807-2812 ◽  
Author(s):  
Patrice de Werra ◽  
Aurélie Huser ◽  
Raphael Tabacchi ◽  
Christoph Keel ◽  
Monika Maurhofer
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Antifungal Compounds ◽  
Content Type ◽  
Expression Of Genes ◽  
Low Molecular Weight Compounds ◽  
Biocontrol Activity ◽  
Genes Encoding ◽  
Antifungal Genes

ABSTRACTWe have investigated the impacts of 63 different low-molecular-weight compounds, most of them plant derived, on thein vitroexpression of two antifungal biosynthetic genes by the plant-protecting rhizobacteriumPseudomonas fluorescensCHA0. The majority of the compounds tested affected the expression of one or both antifungal genes. This suggests that biocontrol activity in plant-beneficial pseudomonads is modulated by plant-bacterium signaling.

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