Application Of Liquid Nitrogen Research Articles

Optimization of the production process of dried unripe olives (Olea europaea L.) as a nutraceutical ingredient naturally rich in phenolic compounds

Phenols from Olea europaea L. exert several beneficial effects on human health. Olive fruits, particularly the unripe ones, thanks to very high phenols contents (e.g. oleuropein, 80,000 mg/kg), can become a new source of income for olive oil producers, with only a negligible reduction of olive oil production. Aim of this research was to define the best process for obtaining dried unripe green olives very rich in phenols from Olea europaea L. analyzing three typical Tuscan cultivars. Four different freezing methods and different combinations of storage times and temperatures were applied to olives before lyophilization for selecting the best procedure to preserve the native phenols. Moraiolo harvested seven-ten days before complete stone lignification showed to be the most suitable cv for production of the ingredient, with oleuropein 100 g/kg and total phenols 178 g/kg. The application of liquid nitrogen immediately followed by lyophilization gave the best results, while other approaches led to losses of oleuropein of at least 68%. As far as storage before lyophilization, the best performance was for olives frozen in liquid nitrogen kept at −80 °C, with a loss of phenols less than 20% after five months, and oleuropein contents still higher than 80,000 mg/kg.

Effect of liquid nitrogen cooling on surface integrity in cryogenic milling of Ti-6Al-4 V titanium alloy

Owing to poor thermal conductivity, heat dissipation, and high chemical reactivity toward most of the tool materials, temperature elevation in the machining of titanium alloy leads to poor surface quality. Based on analyzing the variation laws of the milling forces under cryogenic cooling, the present investigation concerns the surface integrity (surface roughness, micro-hardness, microstructures, and residual stresses) in cryogenic milling of Ti-6Al-4 V alloy under the application of liquid nitrogen (LN2) as a cooling mode. Findings have indicated a dramatic increase in milling forces, and decreasing surface roughness was observed under variation of jet temperature (20~−196 °C). Besides an increase in cutting speed from 60 to 120 m/min, a linear increase in cutting forces, surface roughness, micro-hardness, and residual compressive stress was observed. The minimum micro-hardness decreased at cutting speed of 90 m/min and up to 30 μm in depth. A holistic comparison between obtained results under cryogenic milling and previously studied results under dry milling at same cutting conditions depicted higher micro-hardness and higher compressive residual stress under cryogenic LN2 on the machined surface. However, the residual stress under LN2 cooling conditions tends to decrease relatively slower compared to dry milling. Also, there are no significant differences in grain refinement and twisting under dry and cryogenic LN2 machining. The research work proves the effectiveness of cryogenic milling in improving the surface integrity of the Ti-6Al-4 V alloy.

FIBROMYXOMA IN THE MANDIBLE: CASE REPORT

A 7-year-old black male child complained of increased volume in the face with no relevant medical history. Extraoral physical examination showed an increased volume in the jaw body of the left side, hard to palpation and with unknown evolution time. A painless hard volume increase at the palpation of the vestibule was in the mouth. Computed tomography scan revealed a solid expansive lesion by inflating the vestibular cortical of the jaw body to the left. Incisional biopsy was performed, and the histologic slices stained in hematoxylin and eosin showed a pattern of spindle cells arranged in regular bundles in addition to mitochondrial areas with little cellularity. Immunohistochemistry was positive for vimentin and Ki67 (4%) and negative for smooth muscle actin, desmin, S100, CD34, and caldesmon, leading to a diagnosis of fibromyxoma. The mandibulectomy was performed associated with application of liquid nitrogen for 3 months without signs of local recurrence. A 7-year-old black male child complained of increased volume in the face with no relevant medical history. Extraoral physical examination showed an increased volume in the jaw body of the left side, hard to palpation and with unknown evolution time. A painless hard volume increase at the palpation of the vestibule was in the mouth. Computed tomography scan revealed a solid expansive lesion by inflating the vestibular cortical of the jaw body to the left. Incisional biopsy was performed, and the histologic slices stained in hematoxylin and eosin showed a pattern of spindle cells arranged in regular bundles in addition to mitochondrial areas with little cellularity. Immunohistochemistry was positive for vimentin and Ki67 (4%) and negative for smooth muscle actin, desmin, S100, CD34, and caldesmon, leading to a diagnosis of fibromyxoma. The mandibulectomy was performed associated with application of liquid nitrogen for 3 months without signs of local recurrence.

Wear mechanism of a coated carbide tool in cryogenic machining of AISI 4340

PurposeThe purpose of this study is to investigate wear mechanisms of a multi-layered TiAlN/AlCrN-coated carbide tool during the milling of AISI 4340 steel under cryogenic machining.Design/methodology/approachThe wear progression was measured using a toolmaker microscope and an optical microscope. Later, a field emission scanning electron microscope and energy-dispersive X-ray analysis were used to investigate the wear mechanisms in detail.FindingsA comprehensive analysis revealed that the main causes of tool wear mechanisms were abrasion and adhesion wear on the flank face.Originality/valueThe investigations presented in this paper may be used by the machining industry to prolong the tool life at higher cutting speed by the application of liquid nitrogen.

Comparison between sustainable cryogenic techniques and nano-MQL cooling mode in turning of nickel-based alloy

Mineral based metal working fluids used in machining, results in environmental pollution and occupational health hazards for the operators. Consequently it is necessary to evolve out machining techniques which are environment friendly. In the present work, techniques such as cryogenic cooling and cryogenic treatment have been compared with Al2O3 nanoparticles based MQL cooling method (nMQL) in turning of the nickel based Nimonic 90 alloy. The machining of nickel based alloy has been carried out using the AlTiN coated tungsten carbide inserts of different nose radii. The effects of these cutting environments have been studied by comparing the tool wear, cutting forces, work surface defects, surface finish, and chip underside surfaces. The application of liquid nitrogen as a cooling medium significantly reduced the tool flank wear of the 0.2 mm nose radius insert by 38% as compared to nMQL technique. The SEM investigation of rake face revealed that the cryogenic cooling technique has also prevented the groove formation and peeling of the coating. The effective cushioning effect of liquid nitrogen as coolant improved the surface finish as compared to other techniques. The cryogenic cooling reduced the defects such as material side flow, material redeposition and micro cavities over the machined surface. Overall the cryogenic cooling environment has been found to be the best mode for the machining of the Nimonic 90 alloy.

Thermomechanically coupled numerical simulation of cryogenic orthogonal cutting

During machining of Ti-6Al-4V, high thermal loads arise, which demand for advanced cooling concepts, such as the application of liquid nitrogen. An efficient approach to analyze the thermomechanical mechanisms which influence the tool life and the workpiece distortions is the usage of coupled numerical simulations.In this work, the Finite-Element-Method was used to simulate the tool-workpiece-interaction and the chip formation, whereas the detailed treatment of the nitrogen fluid flow and its heat transfer is solved by an in-house program using the Finite-Difference-Method. Both simulations are coupled by appropriate boundary conditions, which are updated iteratively during the calculation.

Numerical Modeling of Cutting Forces and Temperature Distribution in High Speed Cryogenic and Flood-cooled Milling of Ti-6Al-4V

Achieving high material removal rates in machining of Ti-6Al-4V alloy is challenging due this material’s poor machinability. Thermally- activated tool-wear mechanisms limit tool-life and machining productivity. 3D Finite Element models were developed in DEFORMTM for cryogenic and flood-cooled milling in order to predict the cutting forces and thermal fields generated during machining. The same model was used to determine cutting speeds necessary for high material removal rates at temperatures below the ideal maximum for carbide tools. These simulations revealed that liquid nitrogen application in cryogenic machining reduced cutting temperature by 40%, allowing for longer tool-life and increased machining productivity.

Comparative analyses of multi-pass face-turning of a titanium alloy under various cryogenic cooling and micro-lubrication conditions

Titanium alloys, despite their high strength-to-weight ratio, are considered as difficult-to-machine materials. Their poor machinability is attributed, among other reasons, to the accumulation of intense heat near the cutting edge that leads to brisk tool damage. The tool damage, in turn, causes deterioration of work surface quality, consumption of more energy and hike in machining forces. The paper focuses on application of innovative lubro-cooling approaches and variation in cutting parameters with a fixed material removal rate for the sake of impeding tool damage and improving associated performance measures. Two cryogenic coolants (liquid nitrogen and carbon dioxide snow), minimum quantity of lubrication (micro-lubrication) and hybridization of the two were tested for effective dissipation of heat in face-turning of a commonly used titanium alloy. Additionally, the effects of removing a given volume of the alloy in one and two cutting passes (with a fixed material removal rate) on tool wear, work surface roughness, cutting energy consumption and machining forces were also experimentally investigated. The double-pass approach was found to have performed better regarding surface roughness, cutting energy and machining forces. Hybrid application of liquid nitrogen and micro-lubrication, carbon dioxide snow, and hybrid application of snow and micro-lubrication yielded the best results regarding tool wear, cutting energy consumption, and work surface roughness, respectively. The solitary application of micro-lubrication yielded significant reduction in the cutting force component.

Fatigue properties of Ti-6Al-4V alloy friction stir welding joint obtained under rapid cooling condition

Friction stir welding joints of Ti-6Al-4V titanium alloy were obtained under air and rapid cooling conditions. After post welding heat treatment, the low-cycle fatigue properties of the joints were manly investigated. The results show that the application of liquid nitrogen on the joint top surface decreases the peak welding temperature and the temperature gradient along the joint thickness, which results in a finer and more homogeneous microstructure. Consequently, the improved tensile properties and microhardness are obtained. Fatigue tests show that the joints obtained under rapid cooling condition possess an increased fatigue life. The W-Re alloy contaminations resulting from the tool wear play a significant role in the joint fatigue performance. The fatigue specimens fracture in the SZ due to the existence of contaminations and these contaminations with different sizes have different influences on the fatigue crack initiation and propagation.

Experimental evaluation of diamond burnishing for sustainable manufacturing

Diamond burnishing is one of the most popular surface finishing technique used to achieve an excellent surface finish. The aim of the present study is to investigate the effect of process parameters in diamond burnishing of 17-4 PH stainless steel (PH SS) under cryogenic environment. The requirement of a sustainable environment for various machining processes urged to explore the importance of cryogenic burnishing over other cooling techniques. Surface modification was achieved by the application of liquid nitrogen (LN2) during diamond burnishing. The process parameters considered to reduce the surface roughness (Ra) and increase the surface hardness (H) are burnishing speed, burnishing feed and burnishing force. The diamond burnishing experiments were conducted based on the L9 orthogonal array. The significant parameters and the optimal level of each parameters were determined by using analysis of variance (ANOVA) and main effect plots respectively. Multi-response optimization has been carried out for cryogenic diamond burnishing of 17-4 PH stainless steel by using Taguchi’s grey relation analysis (TGRA). From the TGRA, it was observed that at burnishing speed 73 m min−1, burnishing feed 0.048 mm/rev and burnishing force 150 N, improved diamond burnishing performance characteristics were obtained. An improvement in grey relation grade (GRG) was found to be 38.47%. Cryogenic diamond burnishing has led to modifications in the microstructure and also an improvement in the subsurface hardness of the material.

Effect of Cryogenic Diamond Burnishing on Residual Stress and Microhardness of 17-4 PH Stainless Steel

Diamond burnishing is a cold working process, which produces a work hardened and uniform surface by plastic deformation. The aim of the present work is to study the behavior of diamond burnishing on surface integrity of 17-4 precipitation hardenable stainless steel (PH-SS) under cryogenic, minimum quantity lubrication (MQL) and dry environments. Surface modification was achieved by the application of liquid nitrogen during diamond burnishing. The process parameters considered were speed, feed, burnishing depth and number of passes. Surface integrity characteristics such as microhardness and residual stresses were investigated after diamond burnishing under cryogenic, MQL and dry environments. In cryogenic diamond burnishing, the surface integrity characteristics of 17-4 PH stainless steel has been significantly improved when compared to MQL and dry environments. Maximum microhardness of 395 HV, 369 HV, and 357 HV respectively was observed under cryogenic, MQL and dry environment. The maximum residual stress of -352 MPa, -282 MPa and -195 MPa respectively were recorded for cryogenic, MQL and dry environment.

Effects of intense cooling on microstructure and properties of friction-stir-welded Ti–6Al–4V alloy

ABSTRACTFriction stir welding (FSW) was used to join Ti–6Al–4V alloy in air and under intense cooling conditions. The results show that the application of liquid nitrogen is beneficial in decreasing the peak temperature and in reducing the extent of the high-temperature region during welding, leading to a smaller stir zone (SZ). Intense cooling can lead to refined and homogeneous grains in the SZ, resulting in increased microhardness. The FSW joint produced with intense cooling had a tensile strength of 1020 MPa, which is nearly equivalent to that of the base material and is up to 2.6% higher than for the air-cooled joint. The fractographs for both types of joint were characterised by dimples, indicating that the fractures were ductile.

CFD model of a lab scale cryogenic batch freezer with the investigation of varying effects on the heat transfer coefficient

Cryogenic freezers are commonly applied in the food processing and healthcare industries, and offer a highly effective preservation method without significant product degradation. The modelling of freezers has been conducted mainly around food processing, to observe the cooling rate during the chilling process. Typically, cryogenic freezers operate with a mix of air and nitrogen as the working fluid, with the effects on the heat transfer coefficient being thoroughly noted, in a range of applications. The effect of the heat transfer coefficient has not been investigated in a liquid nitrogen application, with a cryogenic applicability. This paper will focus on the CFD visualisation of the circulation of air around a lab scale cryogenic batch freezer. The effect of the heat transfer coefficient will be investigated in a number of scenarios, such as shelf loading conditions, product configuration and thermal profiles. The cryogenic batch freezer will be simulated in a range of room temperatures starting from -70°C, using a thermal profile which was obtained experimentally.

Compact Self-contained Cryosurgical Devices

Cryosurgery has such advantages as easy implementation, painlessness, high accuracy, low recurrence rate, and lasting cosmetic effect. However, application of liquid nitrogen as a spray or using a cotton swab does not provide cryonecrosis of pathological tissues. The required cooling rate can be obtained using special cryogenic devices. The KM-01 and KM-02 devices are designed for removal of pathologically changed tissues by exposure to liquid nitrogen. The KM-01 device is used for contact cryodestruction. It is implemented as a container for liquid nitrogen coated with thermal insulator. A cannula at the bottom of the container allows replaceable metal tips of various shapes and sizes to be attached to the container. The KM-02 device can be used for both contact and contactless cryodestruction. To provide surgery at poorly accessible areas, the device was made compatible with a large range of tips of complicated shapes, as well as rigid and flexible tubes of various lengths. During contact surgery, both the tip and the skin area in direct contact with the tip are cooled, while in contactless surgery only the skin area is cooled by spraying. The areas of application of the devices include dermatology, cosmetology, dentistry, oncology, surgery, gynecology, and otolaryngology.

Metered Cryospray™: a novel uniform, controlled, and consistent in vivo application of liquid nitrogen cryogenic spray

In this article, a novel cryotherapy approach using a uniform, controlled, and consistent in vivo application of liquid nitrogen (LN2) spray as a Metered Cryospray™ (MCS) process is described. Although MCS may be used for many potential clinical applications, this paper focuses on the development that led to the controlled and consistent delivery of radial LN2 cryogen spray in order to generate a uniform circumferential effect and how the amount of MCS can be adapted to specifically ablate targeted diseases within a patient’s lumen such as an airway or esophagus.

VERIFICATION OF NITROGEN AND PHOSPHORUS APPLICATION RATES TO FLUE-CURED TOBACCO

With rising input costs, flue-cured tobacco producers must consider modern fertility programs that focus on reduced application rates of alternative nutrient sources. To demonstrate the usability of these fertility programs, research was conducted in 2012, 2013, and 2014 to assess the impacts of reduced input fertilizer programs on flue-cured tobacco produced in the North Carolina Piedmont. Treatments evaluated included all possible combinations of 2 rates of liquid nitrogen (72 and 95 kg N/ha) and 3 rates of phosphorus (0, 25, and 56 kg P2O5/ha). Treatments were arranged in a randomized complete block design with a factorial treatment arrangement and replicated 4 times within each environment. Results confirm that lower application rates of nitrogen and phosphorus are acceptable for tobacco growth and development in the North Carolina Piedmont, as there were no differences in early-season tobacco growth or final leaf yield, quality, and value among the treatments imposed. In addition, the application of liquid nitrogen is suitable for the production of tobacco with acceptable leaf yield and quality. Producers in this region should consider the nutrient sources and application rates evaluated in this study in order to remain economically and environmentally sustainable.

Bal Arısı (Apis Mellifera L., 1758) Kolonilerinde Hijyenik Davranışa Etki Eden Faktörler ile Tespit Yöntemlerinin Karşılaştırması Üzerine Bir Çalışma

This study was conducted to determine the better hygienic behaviour determination method that is used in controlling against bee diseases and pests. Total forty honeybee colonies (Apis mellifera anatoliaca) were used and they were randomly divided into two groups (each group consists of twenty colonies) in first year. Liquid nitrogen method was used in the first group' colonies and pin-killing (needling process) method was used in the second group’ colonies to determine the effectiveness of methods for hygienic behaviour. Average clearance rate was found as 66.25% and 78.10% in the first (Liquid nitrogen application) and the second (pin-killing) groups respectively. In the second year, forty colonies were divided into five equal groups and each group consisted eight colonies. The first group consisted of 9 frames bees in standard langstroot hive (10 frame capacity), the second group consisted of 5 frames bees in standard langstroot hive (10 frame capacity), the third group consisted of 5 frames bees in ruşet hive (5 frame capacity), the forth group’s consisted of 3 frames bees in ruşet hive (5 frame capacity) and the fifty group consisted of queen mating hive. The pin-killing (needling process) method, tested in first year, was used for all groups to determine the effectiveness of colony population and the size of hive. Average clearance rates of the first, second, third, forth and fifth groups were 70.54%, 58.38%, 70.63%, 54.96% and 58.21% respectively. The colonies that belonged to the pin-killing (needling) group showed a higher cleaning behaviour rate than the other colonies. The density of bees in hive had an important effect on the clearance rate of colonies. The colonies of group 1 and group 3, which had the more density of bees in per unit area, had the higher clearance rate than the other groups.

Инновационная модель применения жидкого азота для охлаждения ракетного топлива в емкостях заправочных систем наземных комплексов

Инновационная модель применения жидкого азота для охлаждения ракетного топлива в емкостях заправочных систем наземных комплексов

The Application of Liquid Nitrogen Spray Cryotherapy in Treatment of Bronchial Stenosis.

Spray cryotherapy (SCT), the application of liquid nitrogen in a noncontact form, has been demonstrated to have efficacy in treating various types of pathologic lesions of the airway when used as an adjunct with bronchoscopy. The purpose of the study was to evaluate the results of the use of bronchoscopic SCT on the airway in a single institution. We performed a retrospective review of data collected on all patients who underwent SCT to re-establish or improve airway patency in an 11-month period. Patients were classified based on the nature of their disease into benign or malignant. Demographic data, change in luminal patency, and clinical outcomes were recorded. The percent of stenosis was divided into grades according to the following classification: 1, ≤25%; 2, 26% to 50%; 3, 51% to 75%; and 4, ≥76%. We defined successful completion of treatment as obtaining a final patency of grade 1. Twenty-two patients met inclusion criteria, with 45.5% (10 patients) having benign stenosis and 54.5% (12 patients) malignant. At initial bronchoscopic evaluation, the median grade of stenosis was 4 for malignant disease and 3.5 for benign disease. The median final posttreatment grade of stenosis was 2 for malignant disease and 1 for benign. The median improvement in grade of stenosis after treatment was 2 for both malignant and benign causes (Wilcoxon test, P = 0.92). Final patency of grade 1 was achieved in 42% of malignant stenosis and 80% of benign. Overall, 86.4% of patients had an improvement in grade of stenosis after treatment. The rate of morbidity was 4.5% (1/22) of all patients. The median change in grade after treatment was 2 grades of improvement for both the benign and malignant groups. These results provide evidence that the use of SCT is equally efficacious for both types of stenosis with an expectation of overall improvement in luminal patency, offering a safe and effective method of achieving airway patency in a minimally invasive fashion. This study contributes to the small but growing body of literature supporting the use of SCT in benign and malignant disease.

P084 An unusual case of Intradermal “Kissing” Naevus presenting as penile warts

Background/introduction We describe a case of a 38 yr old white heterosexual male with Crohns disease presenting with warty lesions of the penis which were found on histological diagnosis to be benign intradermal naevi. The differential diagnosis included papular warts, skin tags, and in this case Crohns and pyoderma gangrenosum. Aim(s)/objectives Initially presented with two smooth papular warty type lesions on the prepuce and glans adjacent to the coronal sulcus,which had been present for several months causing discomfort during sexual activity and unsightly appearance. Currently taking oral prednisolone and mesalazine for longstanding Crohns disease,with no other cutaneous manifestations, and had regular female partner. Results Initially treated with Liquid Nitrogen application but with minimal resolution and in light of his medical history to exclude “metastatic” Crohns and associated pyoderma gangrenosum a punch biopsy was carried out. Histological appearances were that of a benign intradermal naevus with characteristic nests of naevus cells within the dermis only, there was no atypia present. He was subsequently referred to the urologist for surgical excision of the lesions. Discussion/Conclusion Benign intradermal naevi or “kissing naevi” of Penis such as this are extremely rare there being only a handful previously reported. Due to the dermal location of naevus cells they usually present as skin coloured or slightly pigmented papules and may be confused with warts, skin tags or dermatofibroma. Treatment with surgical excision or laser therapy results in satisfactory functional and aesthetic outcomes.