CO2 Snow Research Articles

Effect of Orthognathic Surgery On Pulp Blood Flow and Pulp Sensibility: A Prospective Control Trial

IntroductionOrthognathic surgery has the potential to compromise the vitality of the teeth. This paper aims to assess changes in pulp blood flow (PBF) and pulp sensibility (PS) of the anterior dentition following orthognathic surgery and to assess the influence of the proximity of the surgical osteotomy on the PBF and/or PS. MethodsTwenty-six patients undergoing orthognathic surgery (Le Fort I or bilateral sagittal split osteotomy [BSSO]) were compared to sixteen control patients treated by fixed appliances only using Laser Doppler flowmeter (LDF) and thermal testing (CO2 snow). Surgery patients were tested at T1 (presurgery), T2 (4-5 weeks postsurgery), T3 (3 months postsurgery), and T4 (6 months postsurgery). Control patients were tested at T1 (pretreatment), T2 (6 months posttreatment), T3 (12 months posttreatment), and T4 (18 months posttreatment). Differences between the maxilla and mandible were assessed. ResultsNo differences in PBF or PS were recorded in the control group. In the surgery group, both jaws followed the same pattern after surgery, an initial decrease at T2 followed by a gradual recovery to pretreatment PBF levels with no significant difference between T1 versus T4 in both jaws. No difference in PBF was observed between the maxilla and mandible at any testing time interval. Conclusions and Clinical ImplicationsPBF and PS of the anterior dentition was severely affected immediately postsurgery, followed by a gradual increase to full recovery. This pattern of recovery was exhibited in both jaws. A negative sensibility response or discoloration should not be seen as an indication of irreversible ischemic pulp changes. Monitoring for at least 6 months or using LDF as a confirmatory test is required before any irreversible endodontic treatment is to be considered.

Measuring Tracers of Planet Formation in the Atmosphere of WASP-77A b: Substellar O/H and C/H Ratios, with a Stellar C/O Ratio and a Potentially Superstellar Ti/H Ratio

We present a comprehensive atmospheric retrieval study of the hot Jupiter WASP-77A b using eclipse observations from the Hubble Space Telescope (HST) and JWST. Using atmospheric retrievals, the spectral features of H2O, CO, and TiO are identified, with volume mixing ratios estimated at log10(VMR) = −4.40 −0.11+0.14 , −4.44 −0.28+0.34 , and −6.40 −0.23+0.22 , respectively. We derive the atmospheric C-to-O ratio—a key planetary formation tracer—to be C/O = 0.54 ± 0.12, which is consistent with both the stellar host value and previous studies of the planet’s atmosphere, suggesting a relatively close-in formation. Computing other elemental ratios (i.e., C/H, O/H, and Ti/H), we conclude that the general enrichment of the atmosphere (i.e., metallicity) is substellar, depleted in C and O, but that Ti appears slightly superstellar. A low C and O content could be obtained, in combination with a stellar C/O ratio if the planet formed outside of the CO2 snow line before migrating inwards. Meanwhile, a superstellar Ti/H could be obtained by late contamination from refractory rich planetesimals. While broadly in agreement with previous works, we do find some differences and discuss these while also highlighting the need for homogeneous analyses when comparative exoplanetology is conducted.

Molecular contamination control for Exomars 2022 Mission

The ExoMars 2022 integration facility has been built at the Thales Alenia Space Italy in Turin. The facility includes a GBT (Glove Box Train), that is an ISO3 class facility, totally aseptic and characterized by controlled airborne molecular organic contamination. This new facility provides an environment strictly controlled for what concerns cleanliness and contamination, specifically conceived to perform AIT of The Ultra Clean Zone (UCZ) of the ExoMars Rover Analytical Laboratory Drawer.Indeed, standard methods as per ECSS-Q-ST-70-05C and ECSS-Q-ST-70-50C are not suitable for the monitoring of integration facility and Flight H/W. The environment of GBT has been required to be monitored in terms of airborne molecular contamination (AMC) on the basis of ISO 14644-8. The maximum contamination levels allowable on flight H/W after accelerated CO2 snow cleaning and at the end of integration activities are one order of magnitude less than the detection limit of standard FT-IR techniques for molecular contamination.For these reasons a dedicated method has been set up for molecular contamination monitoring. This paper shows the development of Thermal Desoprtion-Gas Cromatography/Mass Spectrometer (TD-GC/MS) method for the monitoring of extremely low organic contamination levels both on air samples and on witnesses representative of the Flight H/W, providing also the most recent results obtained in the frame of ExoMars 2022 UCZ QM and FM AIT Campaign.

Keck Planet Imager and Characterizer Emission Spectroscopy of WASP-33b

We present Keck Planet Imager and Characterizer (KPIC) high-resolution (R ∼35,000) K-band thermal emission spectroscopy of the ultrahot Jupiter WASP-33b. The use of KPIC’s single-mode fibers greatly improves both blaze and line-spread stabilities relative to slit spectrographs, enhancing the cross-correlation detection strength. We retrieve the dayside emission spectrum with a nested-sampling pipeline, which fits for orbital parameters, the atmospheric pressure–temperature profile, and the molecular abundances. We strongly detect the thermally inverted dayside and measure mass-mixing ratios for CO (), H2O (), and OH (), suggesting near-complete dayside photodissociation of H2O. The retrieved abundances suggest a carbon- and possibly metal-enriched atmosphere, with a gas-phase C/O ratio of , consistent with the accretion of high-metallicity gas near the CO2 snow line and post-disk migration or with accretion between the soot and H2O snow lines. We also find tentative evidence for 12CO/13CO ∼ 50, consistent with values expected in protoplanetary disks, as well as tentative evidence for a metal-enriched atmosphere (2–15 × solar). These observations demonstrate KPIC’s ability to characterize close-in planets and the utility of KPIC’s improved instrumental stability for cross-correlation techniques.

Effects on general pain perception and dental pulp sensibility in probable sleep bruxism subjects by experimentally induced pain in a pilot study

In this pilot study, the general pain perception and the dental pulp sensibility of probable sleep bruxism (SB) subjects were compared with that of non-SB subjects. The cold pressor test (CPT), electric pulp test (EPT), and thermal pulp test with CO2 snow were executed by one trained dentist (blind to SB diagnosis). A one-factorial multivariate analysis of variance (MANOVA) with SB diagnosis as independent variable and standardized measures regarding pain perception and evaluation was performed. One-hundred-and-five participants (53 SB and 52 non-SB subjects) were included. The one-factorial MANOVA revealed a significant difference between SB and non-SB subjects (p = 0.01) concerning pain perception variables. Post-hoc univariate analyses of variance (ANOVA) showed statistically significant lower general pain tolerance (p = 0.02), higher general subjective sensibility of the teeth (p < 0.01), and a statistical trend for higher subjective dental pain intensity (p = 0.07) in SB subjects. In most of the standardized variables, probable SB subjects seem to react and feel similar to non-SB subjects. However, as probable SB subjects subjectively perceive their teeth to be more sensitive and tend to rate their subjective dental pain intensity more intensely after CO2 testing, data might point to a somatosensory amplification.

CO2 snow jet cleaning as a roll-to-roll compatible method for deburring IMI substrates after laser patterning

Burring is commonly encountered upon patterning of dielectric-metal-dielectric (DMD) transparent electrodes by laser ablation. These burrs are conductive and thus lead to shunting of the (opto-)electronic devices built upon these electrodes. In this work, CO2 snow jet blasting is presented as a convenient and reliable method for deburring laser-patterned DMD electrodes during roll-to-roll manufacturing of organic solar modules. As CO2 snow jet blasting significantly reduces the extent of shunting and concomitantly avoids scratching the electrode, the photoelectrical conversion efficiencies of the solar modules thus produced are higher than those obtained for traditional deburring techniques.

Very High Cycle Fatigue Behavior of Austenitic Stainless Steels with Different Surface Morphologies

The fatigue behavior of the two austenitic stainless steels AISI 904L and AISI 347 with different surface morphologies, (i) conventionally turned and finally polished, (ii) cryogenic turned using CO2 snow, as well as (iii) cryogenic turned and finally polished, was investigated using an ultrasonic fatigue testing system up to the very high cycle fatigue regime using an ultrasonic fatigue testing system. The AISI 904L is stable against deformation-induced phase formation while the AISI 347 is in the metastable state and shows martensite formation induced by cryogenic turning as well as mechanical loading. For the detailed characterization of the surface morphology, confocal microscopy, scanning electron microscopy, and X-ray diffraction methods were used. The specimens from stable austenite failed in the high cycle fatigue and very high cycle fatigue regime. Opposed to this, the metastable austenite achieved true fatigue limits up to load cycle N = 1 × 109 and failed only in the high cycle fatigue regime. Furthermore, due to surface modification, an increase of fatigue strength of metastable AISI 347 was observed.

Broadband spectroscopy of astrophysical ice analogues

Context. Broadband optical constants of astrophysical ice analogues in the infrared (IR) and terahertz (THz) ranges are required for modeling the dust continuum emission and radiative transfer in dense and cold regions, where thick icy mantles are formed on the surface of dust grains. Such data are still missing from the literature, which can be attributed to the lack of appropriate spectroscopic systems and methods for laboratory studies. Aims. In this paper, the THz time-domain spectroscopy (TDS) and the Fourier-transform IR spectroscopy (FTIR) are combined to study optical constants of CO and CO2 ices in the broad THz-IR spectral range. Methods. The measured ices were grown at cryogenic temperatures by gas deposition on a cold silicon window. We developed a method to quantify the broadband THz-IR optical constants of ices, based on the direct reconstruction of the complex refractive index of ices in the THz range from the TDS data and the use of the Kramers-Kronig relation in the IR range for the reconstruction from the FTIR data. Uncertainties introduced by the Kramers-Kronig relations were eliminated by merging the THz and IR spectra. Finally, the reconstructed THz-IR response was analyzed using classical models of complex dielectric permittivity. Results. The complex refractive index of CO and CO2 ices deposited at the temperature of 28 K was obtained in the range of 0.312.0 THz and fitted using the analytical Lorentz model. Based on the measured dielectric constants, opacities of the astrophysical dust with CO and CO2 icy mantles were computed. Conclusions. The method developed in this work can be used for a model-independent reconstructions of optical constants of various astrophysical ice analogs in a broad THz-IR range. Such data can provide important benchmarks for interpreting broadband observations from existing and future ground-based facilities and space telescopes. The reported results will be useful in modeling sources that exhibit a drastic molecular freeze-out, such as the central regions of prestellar cores and mid-planes of protoplanetary disks, as well as CO and CO2 snow lines in disks.

Key initiatives to improve the machining characteristics of Inconel-718 alloy: Experimental analysis and optimization

Inconel 718 is a heat-resistant Ni-based superalloy widely used, particularly, in aircraft and aero-engineering applications. It has poor machinability due to its unique thermal and mechanical properties. For this reason, studies have been carried out from past to present to improve the machinability of Nickel-based (Ni) alloys. Further improvement can be achieved by applying hybrid multi-objective optimization strategies to ensure that cutting parameters and cooling/lubrication strategies are also adjusted effectively. That is why, in this research, the machinability of Inconel 718 is optimized under various sustainable lubricating environments i.e., dry medium, minimum quantity lubrication (MQL), nano-MQL, and cryogenic conditions at different machining parameters during end-milling process. Subsequently, the analysis of variance (ANOVA) approach was implanted to apprehend the impact of each machining parameter. Finally, to optimize machining environments, two advanced optimization algorithms (non-dominated sorting genetic algorithm II (NSGA-II) and the Teaching-learning-based optimization (TLBO) approach) were introduced. As a result, both methods have demonstrated remarkable efficiency in machine response prediction. Both methodologies demonstrate that a cutting speed of 90 m/min, feed rate of 0.05 mm/rev, and CO2 snow are the optimal circumstances for minimizing machining responses during milling of Inconel 718.

Distant Formation and Differentiation of Outer Main Belt Asteroids and Carbonaceous Chondrite Parent Bodies

AbstractVolatile compositions of asteroids provide information on the Solar System history and the origins of Earth's volatiles. Visible to near‐infrared observations at wavelengths of &lt;2.5 µm have suggested a genetic link between outer main belt asteroids located at 2.5–4 au and carbonaceous chondrite meteorites (CCs) that show isotopic similarities to volatile elements on Earth. However, recent longer wavelength data for large outer main belt asteroids show 3.1 μm absorption features of ammoniated phyllosilicates that are absent in CCs and cannot easily form from materials stable at those present distances. Here, by combining data collected by the AKARI space telescope and hydrological, geochemical, and spectral models of water‐rock reactions, we show that the surface materials of asteroids having 3.1 μm absorption features and CCs can originate from different regions of a single, water‐rock‐differentiated parent body. Ammoniated phyllosilicates form within the water‐rich mantles of the differentiated bodies containing NH3 and CO2 under high water‐rock ratios (&gt;4) and low temperatures (&lt;70°C). CCs can originate from the rock‐dominated cores, that are likely to be preferentially sampled as meteorites by disruption and transport processes. Our results suggest that multiple large main belt asteroids formed beyond the NH3 and CO2 snow lines (currently &gt;10 au) and could be transported to their current locations. Earth's high hydrogen to carbon ratio may be explained by accretion of these water‐rich progenitors.

Salix shrub encroachment along a 1000 m elevation gradient triggers a major ecosystem change in the European Alps

Shrub encroachment, a globally recognized response to climate warming, usually involves late successional species in mountain environments, without alteration to climax communities. We show that a major ecosystem change is occurring in the European Alps across a 1000 m elevation gradient, with pioneer hygrophilous Salix shrubs, previously typical of riparian forests, wetlands and avalanche ravines, encroaching into the climax communities of subalpine and alpine belts shrublands and grasslands, as well as snowbeds, pioneer vegetation and barren grounds in the nival belt.We analyzed Salix recruitment through dendrochronological methods, and assessed its relationships with climate and atmospheric CO2 concentration. The dendrochronological data indicated that Salix encroachment commenced in the 1950s (based on the age of the oldest Salix individuals, recruited in 1957), and that it was correlated with increasing atmospheric CO2 concentration, spring warming and snow cover decrease. Hygrophilous Salix shrubs are expanding their distribution both through range filling and upwards migration, likely achieving competitive replacement of species of subalpine and alpine climax communities. They benefit from climate warming and CO2 fertilization and are not sensitive to spring frost damage and soil limitations, being observed across a gradient of soil conditions from loose glacial sediments in recently deglaciated areas (where soils had not had sufficient time to develop) to mature soils such as podzols (when colonizing late successional subalpine shrublands).Salix encroachment may trigger ecosystem and landscape transformations, promoting the development of forests that replace pre‐existing subalpine shrublands, and of open woodlands invading alpine grasslands and snowbeds, making the alpine environment similar to sub‐Arctic and Arctic areas. This results in a new threat to the conservation of the plant species, communities and landscapes typical of the alpine biota, as mountain ranges such as the Alps provide limited opportunities for upward migration and range‐shift.

Carbon dioxide snow cleaning of paper

The cleaning of particles from smooth and rough paper surfaces using a high-speed CO2 snow jet was investigated. The measurements included characterization of the jet properties, determination of the cleaning efficiency, and evaluation of any possible adverse effects. The method was compared with nitrogen jet cleaning and dry cleaning by commercial materials. The results showed that the CO2 snow jet is able to effectively remove particles from the paper surface and did not cause any observable degradation. The CO2 snow jet cleaning compared with the mechanical dry cleaning showed similar effectiveness without any adverse effects on the paper surface. It was proved that the CO2 snow technique is a suitable method for cleaning common types of paper materials.

Cryogenically Applied Support and Damping Structures for Chatter Suppression in the Machining of Thin-Walled Components

Lightweight components with low wall thickness continue to gain technological and economic importance in aerospace and other industries. Thereby, the low wall thickness and thus high compliance of such workpieces may cause the occurrence of undesired vibrations under the characteristic load of machining operations. The suppression of dynamic effects such as regenerative chatter represents a central requirement for milling operations with regard to the achievable component qualities and process efficiency. Certain approaches base on the application of support structures or damping elements, which are attached to the workpiece. After processing the thin-walled components, however, the added structures have to be removed in elaborate processes. In this paper, a new approach is presented which is focusing on an optimised process stabilisation method using cryogenic solidified coolant. By injecting coolant emulsion into the CO2 snow jet and applying it specifically to thin-walled workpieces, stiffening support structures were generated and damping elements attached. The ice layer melts off after machining and returns into the lubricant circuit with no need for conditioning or additional filtering. Modal tests and machining experiments demonstrated the applicability of the presented approach and a significant decrease of the dynamic compliance and deflection of the workpiece during milling operations.

Pulp blood flow and sensibility in patients with a history of dental trauma undergoing maxillary expansion.

To assess changes in pulp blood flow (PBF) and pulp sensibility (PS) in teeth of patients with a history of dental trauma undergoing maxillary expansion. Twenty-five patients requiring rapid maxillary expansion (RME) had the pulp status of their maxillary anterior teeth assessed using laser Doppler flowmetry, electric pulp testing, and thermal testing (CO2 snow). Each patient was tested at T1 (prior to expansion), T2 (2 weeks after rapid expansion), and T3 (3 months after expansion). Relationships between PBF, time interval, and history of trauma were evaluated using linear mixed modelling. Within the Trauma group, PBF was significantly lower (P ≤ .05) at T2 and T3 in comparison to T1 and significantly lower (P ≤ .05) at T2 in comparison to T3. In the Non-trauma group, PBF at T2 was significantly lower (P ≤ .05) than PBF at T1 and T3; however, no significant difference (P > .05) in PBF was observed when comparing PBF at T1 and T3. In both groups, PS was maintained in almost all teeth (>90%). RME in healthy teeth causes reduction of PBF before reestablishment of pretreatment values. RME in traumatized teeth causes reduction of PBF without PBF being reestablished to pretreatment levels. Teeth with a history of compromise may have reduced adaptive capacity under insults such as RME, which should be appreciated during the informed consent process.

Influence of CO2-snow and subzero MQL on thermal aspects in the machining of Ti-6Al-4V

Having a low thermal conductivity, the aerospace alloy Ti-6Al-4V is well-acknowledged as to retain an elevated thermal state in machining and shows poor machinability. An enhanced heat transfer during cutting is hypothesized to reduce the high cutting temperature and result in improved machining performance. Conventional flood cooling is reported as an ‘ineffective’ method to remove heat properly. As such, the advanced novel systems like carbon dioxide snow (CO2-snow) and subzero minimum quantity lubrication (MQL) spray have the potential to pacify the hot cutting zone. The present study investigates the heat transfer capability of CO2-snow and subzero MQL. Afterward, their thermal behavior has been related to the critical machinability metrics such as cutting temperature, cutting force, surface roughness, tool wear, chip analysis, and residual stresses with reference to conventional flood cooling to underscore their overall benefits. The statistical analysis has shown that a higher value of the coefficient of heat transfer (1347 W/m2C) was attained under CO2-snow compared to subzero MQL spray (486 W/m2C). Moreover, the order of overall better machinability has derived as CO2-snow > flood cooling > subzero MQL. Furthermore, the relatively superior heat transfer behavior of CO2-snow in machining resulted in reduced tool wear (i.e., prolonged tool life), and an improved surface finish. In summary, the CO2 snow showed promising results to warrant its application in the machining industry.

Effects of CO2 snow addition during kneading on thermoregulation, dough rheological properties, and bread characteristics: A focus on ancient and modern wheat cultivars

Bread and baked products are an essential source of protein, dietary fiber, vitamins, micronutrients, and antioxidants. Unfortunately, the use of weak, and whole wheat flours creates significant rheological problems and results in bread with inadequate characteristics (e.g. low volume and height). In this context, an important harmful effect is dough warming during kneading, which worsens both rheological properties and bread characteristics. Thus, improvement strategies need to be found. This paper assesses the effects of the addition during kneading of an alternative refrigerant, namely CO2 snow, on dough temperature, dough rheological properties, and bread characteristics. Two types of flour were tested: a modern wheat cultivar (Bologna) and an ancient wheat cultivar (Verna). Six percentages of CO2 snow were tested: 0% (control, no CO2 snow), 2%, 4%, 6%, 8%, and 10%. Our results show the effectiveness of CO2 snow addition on dough thermoregulation and the improvement of bread characteristics. High percentages of CO2 snow (6%, 8%, and 10%) lowered the final dough temperature 2°C, 3°C, and 4°C respectively. Furthermore, specific volume and loaf height increased, and crumb density slightly decreased, both for Verna and Bologna flours. Other advantages of this alternative refrigerant include its ease of application, higher cooling power compared to other refrigerants, no increase in dough total water content, and no chemical or toxic residuals.

Adsorption and reaction layers when turning AISI 304 using various cooling strategies

Abstract This paper deals with the surface chemistry of face-turned workpieces of AISI 304 using various cooling conditions. The workpieces were machined by means of LN2 cooling, CO2 snow cooling, conventional emulsion, sub-zero MWF as well as dry machining. With regard to the machining process, the tool temperature, the process forces, and the surface topography are investigated. The surface chemistry is studied using X-ray photoelectron spectroscopy (XPS). These investigations focus firstly on a detection of the elements occurring on the surface, their concentration and the dominant binding state of the main components. Especially the oxidation state of the surface due to the thermal load in the tool-work interface during machining is analyzed on the basis of O 1s and Fe 2p3 core level photoelectron spectra. Secondly, sputter depth profiling using XPS is performed in order to qualitatively analyze the surface depth distribution of the detected elements. Adsorption and reaction layers can occur during turning of AISI 304 up to a depth of approximately 7 nm depending on the cooling conditions used. The use of emulsion, CO2 snow and dry machining results in a slightly higher carbon concentration. Regarding the oxidation in the reaction layer it can be concluded, that the higher the temperatures in the tool at distance of 1 mm to the contact zone during machining, the more oxidation occurs in these layers.

Influence of different cooling strategies during hard turning of AISI 52100 - part I: thermo-mechanical load, tool wear, surface topography and manufacturing accuracy

This paper presents a characterization of the turning process for finishing of AISI 52100 in martensitic heat treatment state at various cooling conditions. With regard to the cooling conditions, LN2-cooling, CO2 snow cooling at varied mass flows, sub-zero metalworking fluids (MWF) at varied supply temperatures, and dry machining were examined. The tool temperatures, the process forces, the tool wear, the surface topography as well as the dimensional deviations of the workpiece caused by unintended alterations of the depth of cut due to a thermal expansion or contraction of the workpiece are analyzed. The application of MWF supplied at 20 °C results in an unchanging thermo-mechanical load in the tool-work interface and surface topography as well as in a high manufacturing accuracy. Dry machining leads to an increasing depth of cut of up to 10 %, resulting in radial dimensional errors. Cryogenic machining and using the sub-zero MWF supplied at -30 °C exhibit a different behavior due to high cooling effects: the depth of cut is reduced up to 10 %, also leading to radial dimensional errors. However, even though the depth of cut and thus the undeformed chip cross section is affected by up to 10 % depending the cooling condition, the mechanical load remains approximately constant during single cuts. In part II, the surface and near surface microstructure morphology of the workpieces is characterized.

Nonsticky Ice at the Origin of the Uniformly Polarized Submillimeter Emission from the HL Tau Disk

Abstract Recent (sub)millimeter polarimetric observations toward the young star HL Tau have successfully detected polarization emission from its circumstellar disk. The polarization pattern observed at 0.87 mm is uniform and parallel to the disk’s minor axis, consistent with the self-scattering of thermal emission by dust particles whose maximum radius is ≈100 μm. However, this maximum size is considerably smaller than anticipated from dust evolution models that assume a high sticking efficiency for icy particles. Here we show that the unexpectedly small particle size can be explained if CO2 ice covers the particles in the outer region of the HL Tau disk. CO2 ice is one of the most major interstellar ices, and laboratory experiments show that it is poorly sticky. Based on dust evolution models accounting for CO2 ice mantles, as well as aggregate sintering, we simulate the polarimetric observation of HL Tau at 0.87 mm. We find that the models with CO2 ice mantles better match the observation. These models also predict that only particles lying between the H2O and CO2 snow lines can grow to millimeter to centimeter sizes and that their rapid inward drift results in a local dust gap similar to the 10 au gap of the HL Tau disk. We also suggest that the millimeter spectral index for the outer part of the HL Tau disk is largely controlled by the optical thickness of this region and does not necessarily indicate dust growth to millimeter sizes.

Machinability of Alloy Steel and Titanium Alloy under Carbon Dioxide Snow, Micro-lubrication and Hybrid Lubro- Cooling

Efficient removal of process heat in machining of high-strength alloys is critical to product quality, process cost and productivity. The paper experimentally investigates the effects of employing a cryogenic coolant (CO2 snow), micro-lubrication and hybridization of the two on the performance measures, such as tool damage, machining forces and specific cutting energy in cutting of two commonly used high-strength alloys, Ti-6Al-4V and 40NiCrMo6. It was found that although the aforementioned cooling approached improved machinability of both the alloys but the titanium based alloy remained more difficult-to-cut than the alloy steel. Hybrid lubro-cooling and CO2 snow cooling proved to be the most effective options for machining of 40NiCrMo6 and Ti-6Al-4V, respectively.