Comparison of long-term kidney functions after radical nephrectomy and simple nephrectomy

Objective To determine if there is a difference in proceeding to CKD between patients who had undergone radical nephrectomy (RN) and simple nephrectomy (SN) for different indications by comparing the short- and long-term renal function. Materials and Methods We retrospectively analyzed the records of all patients who underwent nephrectomy (either for malign or benign indications) in our clinic between January 2007 and September 2017. The patients were divided into 2 groups according the type of surgery: 1) Radical nephrectomy Group, 2) Simple Nephrectomy Group. Renal function was evaluated with Glomerular Filtration Rate (GFR) calculated using the MDRD formula. Results A total of 276 patients were included in the study. There were 202 patients in RN Group and 74 patients in SN Group. The mean age of the patients in RN Group and SN Group were age 59,2 ± 11,5 and 49,9 ± 15,1 years, respectively (p = 0.001). GFR levels of patients in RN Group versus SN Group were as follows: Preoperative period: 84.9 vs. 81 mL/min/1.73 m2; postoperative 1st day: 60.5 vs. 84.4 mL/min/1.73 m2, postoperative 1st month 58.9 vs. 76 mL/min/1.73 m2, postoperative 1st year: 59.5 vs. 74.1 mL/min/1.73 m2; at last control 60.3 and 76.1 mL/min/1.73 m2. While preoperative GFR was found to be similar in two groups (p = 0.26), postoperative GFR values were found to be significantly lower in Group RN (p < 0.001). In comparison of the decrease in GFR in two groups at last follow-up, significantly higher decrease was observed in RN Group, 29% vs. 6%, (p < 0.05). Conclusion The decrease in GFR exists more common and intensive after RN compared to SN. In long-term, compensation mechanisms that develop after sudden nephron loss like radical nephrectomy deteriorates kidney function more than gradual nephron loss as in benign etiologies which indicates simple nephrectomy

Effects of hybrid nanofluids on machining performance in MQL-milling of Inconel X-750 superalloy

Friction and high temperatures greatly affect machining efficiency when machining superalloy materials. Nanoparticles with high thermal conductivity and lubricity are preferred for increase lubricant performance. Nanofluids prepared with nanoparticles not only reduce environmental concerns but also positively affect the machining efficiency in the sustainable manufacturing process. However, some nanoparticles added in mono form stand out with their thermal conductivity and some nanoparticles with their lubricating performance. For this reason, the lubrication performance of hybrid nanofluids prepared with nanoparticles with different superior properties is a matter of interest. In this study, the machining performance of Inconel X-750 superalloy was investigated by using hexagonal boron nitride (hBN), graphite (Grpt), and MoS2 nanoparticles with different shapes and properties. For this purpose, the milling experiments were performed under three different hybrid nanofluid (hBN/Grpt, hBN/MoS2, and Grpt/MoS2) conditions, at three different cutting speeds (30, 45, and 60 m/min), and three different feed rates (0.05, 0.10, and 0.15 mm/rev). Cutting force, cutting temperature, surface roughness/topography, tool wear, and tool life were selected as machining performance criteria. According to the results obtained from the experiments, it was understood that the hBN/Grpt hybrid nanofluid outperformed hBN/MoS2 and Grpt/MoS2 conditions in all performance criteria. hBN/Grpt hybrid nanofluid achieved 36.17% and 6.08% improvement in tool life compared to Grpt/MoS2 and hBN/MoS2 nanofluids, respectively.Duzce University (Turkey) Research FundDuzce University [2017.07.04.593]The authors wish to thank the Duzce University (Turkey) Research Fund for their financial support of this experimental study (Project Number: 2017.07.04.593).WOS:0006963269000062-s2.0-8511410550

Evaluation of the tribological performance of the green hBN nanofluid on the friction characteristics of AISI 316L stainless steel

Purpose The purpose of this study is to investigate the effect of new green hexagonal boron nitride (hBN) nanofluid on AISI 316L stainless friction coefficient, wear resistance and wear using a ball on disc tester. Design/methodology/approach Nanofluids were prepared by adding hBN nanoparticles with two-step method to the vegetable-based oil at 0.50 vol%. Before the experiments, hBN nanofluid viscosity, pH and thermal conductivity specifications were determined. Friction tests of AISI 316L stainless steel were performed under 2 N, 5 N and 8 N loads at 400 rpm using a ball-on-disc test device under dry, oil and hBN conditions. Coefficient of friction, wear profile, surface integrity and wear mechanisms were chosen as performance criteria. Findings The friction coefficient values obtained under the oil and hBN test conditions with the 8 N load were, respectively, 72.46% and 77.64% lower than those obtained under dry test conditions. hBN nanofluid performed better on surface topography, and especially wear, compared to the dry and oil test conditions. Practical implications The aim of this study was to determine the best tribological performance of the hBN nanofluid on AISI 316L stainless steel used in orthopedic applications. Originality/value The paper is a study investigating the effect of hBN nanoparticle additive in vegetable-based oil on friction and wear performance of AISI 316L stainless steel. It is an original paper and is not published elsewhere.WOS:0006848212000012-s2.0-8511219277

Performance of cryogenically treated carbide inserts under sustainable cryo-lubrication assisted milling of Inconel X750 alloy

Owing to their superior features even under elevated temperatures, the nickel-based superalloy Inconel X750 is among the materials demanded in many critical areas. However, such alloys are hard to cut because of their characteristic properties i.e., strain hardening, poor thermal conductivity, high mechanical resistance at elevated temperature, the presence of abrasive carbide fragments and chemical proximity. Therefore, it is important to develop the machinability characteristics of these materials with sustainable machining methods that offer high performance. For this, in this work, a number of attempts were made during the milling of the Inconel X750 alloy. During the experiments, the performance of each cutting tool was investigated by considering three different tools which are uncoated carbide tool, cryogenically treated cutting tool and TiAlN coated tool. Since the machinability of superalloys is difficult in the dry environment, three different sustainable cooling/lubrication conditions such cryogenic LN2, MQL and hybrid cooling/lubrication (MQL + LN2) have been used in conjunction with these tools. In evaluating the effectiveness of the employed methods, flank wear, tool damage types, surface roughness/topography, cutting force and maximum temperatures were analyzed. As a result, even if the cryogenically treated tool performed slightly better than those of untreated, it still did not reach the performance level of the TiAlN coated tools. The hybrid cooling/lubrication system with coated tool offered the best solution in terms of all criteria. On the other hand, MQL outperforms LN2 cooling for tool wear, surface roughness/topography and cutting force, LN2 cooling is better than MQL in temperature reducing

Study on turning performance of PVD TiN coated Al2O3+TiCN ceramic tool under cutting fluid reinforced by nano-sized solid particles

Due to their excellent chemical stability, hardness and abrasion resistance, ceramic cutting tools are suitable for operations at very high cutting speeds, which play a decisive role in high productivity. Thanks to these properties, they are significantly resistant to high temperatures occurred in the cutting zone. However, after a certain point, excessive temperature rise in the cutting zone brings some problems. This is seen as a problem that should be overcome as it affects negatively machining efficiency. However, the poor resistance of ceramic tools to thermal shocks is an important factor restricting the use of flood cooling. Alternatively, promising results have been achieved recently in MQL and nanofluid-MQL applications particularly on carbide cutting tools. When these methods are used together with ceramic cutting tools, the behavior of ceramic cutters and their effect on machinability outputs is still a matter of curiosity. Therefore, in order to observe the interaction between ceramic cutting tool and minimum quantity lubrication (MQL) and nanofluid-MQL, we investigated the turning performance of PVD TiN coated Al2O3+TiCN ceramic tool under dry, pure-MQL and nanofluid-MQL reinforced by nano-sized solid particles such as graphene nanoplatelets (GNPs) and multi walled carbon nanotubes (MWCNTs). Experiments were carried out to investigate the effect of cooling/lubrication (C/L) environment and cutting parameters on tool life, surface roughness and maximum temperature of chip. In addition, a series of experiments were also made to observe the effect of only C/L environment on the wear behavior of the ceramic tools and the machined surface topography while keeping the cutting parameters constant. As a result, pure-MQL contributed to the reduction of nose wear by about 69% compared to dry machining, while GNPs based nanofluid-MQL helped to reduce the surface roughness by 19.42%.WOS:0005583203000072-s2.0-8508484906

Machinability performance of nickel alloy X-750 with SiAlON ceramic cutting tool under dry, MQL and hBN mixed nanofluid-MQL

Nickel alloy X-750 which is difficult-to-machine material, is employed in many critical fields owing to its superior mechanical and thermal properties. However, these superior features lead to some difficulties in its machinability especially when using carbide tool materials. Hence, ceramic cutting tools (CCTs) having excellent hardness, heat and abrasion resistance, and poor chemical proximity to workpiece material are a perfect choice in machining operations of such materials. Considering this, the current study focused on the influence of various cutting environment, i.e., dry, base fluid-MQL without any mixed nanoparticles (BF-MQL) and hBN dispersed nanofluid-MQL (NF-MQL) on surface roughness, 2D-surface topography, maximum cutting temperature, cutting force, micro-hardness, flank wear and its mechanism when milling of alloy X-750 with Sialon ceramic tools. As a result, surface roughness was reduced by about 39% and 47.2% with BF-MQL (0 vol% additive) and hBN mixed NF-MQL, respectively compared to dry machining environment. Also the noticeable improvement with NF-MQL environment in 2D-surface topography of workpice, cutting temperature and cutting force has been achieved, the dry machining offered less tool wear for CCT than both BF-MQL and NF-MQL.Duzce University (Turkey) Research FundDuzce University [2017.07.04.593]This work was supported by the Duzce University (Turkey) Research Fund (Project Number: 2017.07.04.593).WOS:0005827559000982-s2.0-8509158665

Evaluation of tool wear, surface roughness/topography and chip morphology when machining of Ni-based alloy 625 under MQL, cryogenic cooling and CryoMQL

Although nickel-based aerospace superalloys such as alloy 625 have superior properties including high-tensile and fatigue strength, corrosion resistance and good weldability, etc., its machinability is a difficult task which can be solved with alternative cooling/lubrication strategies. It is also important that these solution methods are sustainable. In order to facilitate the machinability of alloy 625 with sustainable techniques, we investigated the effect of minimum quantity lubrication (MQL), cryogenic cooling with liquid nitrogen (LN2) and hybrid-CryoMQL methods on tool wear behavior, cutting temperature, surface roughness/topography and chip morphology in a turning operation. The experiments were performed at three cutting speeds (50, 75 and 100 mirnin), fixed cutting depth (0.5 mm) and feed rate (0.12 mm/rev). As a result, CryoMQL improved surface roughness (1.42 mu m) by 24.82% compared to cryogenic cooling. The medium level of cutting speed (75 mirnin) can be preferred for the lowest roughness value and lowest peak-to-valley height when turning of alloy 625. Further, tool wear is decreased by 50.67% and 79.60% by the use of MQL and CryoMQL compared with cryogenic machining. An interesting result that MQL is more effective than cryogenic machining in reducing cutting tool wear. (C) 2019 The Authors. Published by Elsevier B.V.Erciyes University Research FundErciyes University [FBA/2018/8074]The authors thank the Erciyes University Research Fund for financial support (Project Number: FBA/2018/8074).WOS:00052195230009

Machinability performance of nickel alloy X-750 with SiAlON ceramic cutting tool under dry, MQL and hBN mixed nanofluid-MQL

Nickel alloy X-750 which is difficult-to-machine material, is employed in many critical fields owing to its superior mechanical and thermal properties. However, these superior features lead to some difficulties in its machinability especially when using carbide tool materials. Hence, ceramic cutting tools (CCTs) having excellent hardness, heat and abrasion resistance, and poor chemical proximity to workpiece material are a perfect choice in machining operations of such materials. Considering this, the current study focused on the influence of various cutting environment, i.e., dry, base fluid-MQL without any mixed nanoparticles (BF-MQL) and hBN dispersed nanofluid-MQL (NF-MQL) on surface roughness, 2D-surface topography, maximum cutting temperature, cutting force, micro-hardness, flank wear and its mechanism when milling of alloy X-750 with Sialon ceramic tools. As a result, surface roughness was reduced by about 39% and 47.2% with BF-MQL (0 vol% additive) and hBN mixed NF-MQL, respectively compared to dry machining environment. Also the noticeable improvement with NF-MQL environment in 2D-surface topography of workpice, cutting temperature and cutting force has been achieved, the dry machining offered less tool wear for CCT than both BF-MQL and NF-MQL

Performance of cryogenically treated carbide inserts under sustainable cryo-lubrication assisted milling of Inconel X750 alloy

Owing to their superior features even under elevated temperatures, the nickel-based superalloy Inconel X750 is among the materials demanded in many critical areas. However, such alloys are hard to cut because of their characteristic properties i.e., strain hardening, poor thermal conductivity, high mechanical resistance at elevated temperature, the presence of abrasive carbide fragments and chemical proximity. Therefore, it is important to develop the machinability characteristics of these materials with sustainable machining methods that offer high performance. For this, in this work, a number of attempts were made during the milling of the Inconel X750 alloy. During the experiments, the performance of each cutting tool was investigated by considering three different tools which are uncoated carbide tool, cryogenically treated cutting tool and TiAlN coated tool. Since the machinability of superalloys is difficult in the dry environment, three different sustainable cooling/lubrication conditions such cryogenic LN2, MQL and hybrid cooling/lubrication (MQL + LN2) have been used in conjunction with these tools. In evaluating the effectiveness of the employed methods, flank wear, tool damage types, surface roughness/topography, cutting force and maximum temperatures were analyzed. As a result, even if the cryogenically treated tool performed slightly better than those of untreated, it still did not reach the performance level of the TiAlN coated tools. The hybrid cooling/lubrication system with coated tool offered the best solution in terms of all criteria. On the other hand, MQL outperforms LN2 cooling for tool wear, surface roughness/topography and cutting force, LN2 cooling is better than MQL in temperature reducing.Duzce University (Turkey) Research FundDuzce University [2017.07.04.593]Y The present study was supported by Duzce University (Turkey) Research Fund (Project Number: 2017.07.04.593) .WOS:0006925611000022-s2.0-8510921308

Study on turning performance of PVD TiN coated Al2O3+TiCN ceramic tool under cutting fluid reinforced by nano-sized solid particles

Due to their excellent chemical stability, hardness and abrasion resistance, ceramic cutting tools are suitable for operations at very high cutting speeds, which play a decisive role in high productivity. Thanks to these properties, they are significantly resistant to high temperatures occurred in the cutting zone. However, after a certain point, excessive temperature rise in the cutting zone brings some problems. This is seen as a problem that should be overcome as it affects negatively machining efficiency. However, the poor resistance of ceramic tools to thermal shocks is an important factor restricting the use of flood cooling. Alternatively, promising results have been achieved recently in MQL and nanofluid-MQL applications particularly on carbide cutting tools. When these methods are used together with ceramic cutting tools, the behavior of ceramic cutters and their effect on machinability outputs is still a matter of curiosity. Therefore, in order to observe the interaction between ceramic cutting tool and minimum quantity lubrication (MQL) and nanofluid-MQL, we investigated the turning performance of PVD TiN coated Al2O3+TiCN ceramic tool under dry, pure-MQL and nanofluid-MQL reinforced by nano-sized solid particles such as graphene nanoplatelets (GNPs) and multi walled carbon nanotubes (MWCNTs). Experiments were carried out to investigate the effect of cooling/lubrication (C/L) environment and cutting parameters on tool life, surface roughness and maximum temperature of chip. In addition, a series of experiments were also made to observe the effect of only C/L environment on the wear behavior of the ceramic tools and the machined surface topography while keeping the cutting parameters constant. As a result, pure-MQL contributed to the reduction of nose wear by about 69% compared to dry machining, while GNPs based nanofluid-MQL helped to reduce the surface roughness by 19.42%