The purpose of this investigation was to compare the efficacy of colistin-based therapies in extremely drug-resistant
Acinetobacter
spp. bloodstream infections (XDR-ABSI). A retrospective study was ...conducted in 27 tertiary-care centers from January 2009 to August 2012. The primary end-point was 14-day survival, and the secondary end-points were clinical and microbiological outcomes. Thirty-six and 214 patients 102 (47.7 %): colistin–carbapenem (CC), 69 (32.2 %): colistin–sulbactam (CS), and 43 (20.1 %: tigecycline): colistin with other agent (CO) received colistin monotherapy and colistin-based combinations, respectively. Rates of complete response/cure and 14-day survival were relatively higher, and microbiological eradication was significantly higher in the combination group. Also, the in-hospital mortality rate was significantly lower in the combination group. No significant difference was found in the clinical (
p
= 0.97) and microbiological (
p
= 0.92) outcomes and 14-day survival rates (
p
= 0.79) between the three combination groups. Neither the timing of initial effective treatment nor the presence of any concomitant infection was significant between the three groups (
p
> 0.05) and also for 14-day survival (
p
> 0.05). Higher Pitt bacteremia score (PBS), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Charlson comorbidity index (CCI), and prolonged hospital and intensive care unit (ICU) stay before XDR-ABSI were significant risk factors for 14-day mortality (
p
= 0.02,
p
= 0.0001,
p
= 0.0001,
p
= 0.02, and
p
= 0.01, respectively). In the multivariable analysis, PBS, age, and duration of ICU stay were independent risk factors for 14-day mortality (
p
< 0.0001,
p
< 0.0001, and
p
= 0.001, respectively). Colistin-based combination therapy resulted in significantly higher microbiological eradication rates, relatively higher cure and 14-day survival rates, and lower in-hospital mortality compared to colistin monotherapy. CC, CS, and CO combinations for XDR-ABSI did not reveal significant differences with respect to 14-day survival and clinical or microbiological outcome before and after propensity score matching (PSM). PBS, age, and length of ICU stay were independent risk factors for 14-day mortality.
Airport terminal buildings consume more energy than other buildings in an airport due to their functional and operational characteristics. Heating, ventilation and air conditioning (HVAC) systems ...have been major energy consumers with a significant contribution to the annual total energy consumption in terminal buildings particularly in harsh climates. Therefore, improvement of energy efficiency of the HVAC system is becoming an increasingly important issue to reduce energy consumption and CO2 emissions of existing terminal buildings. The aim of this study is to analyze and evaluate the effect of various energy conservation strategies on energy consumption and CO2 emissions, including a number of modifications that can be applied to the HVAC system of airport terminal buildings. Erzurum Airport terminal building, located in the coldest climate zone of Turkey, was chosen as the airport terminal building. In order to achieve this goal, six strategies that can create energy savings and cost savings and provide environmental benefits were analyzed and evaluated by building energy simulation. The results indicated that energy consumption could be reduced from 6.3 GWh/year to 2.7 GWh/year and CO2 emissions from 1.9 million kg/year to 0.9 million kg/year by implementing feasible energy conservation strategies. This means that, by implementing the proposed energy-saving projects, energy consumption and CO2 emissions can be reduced by 57.24% and 48.79%, respectively.
•HVAC systems are major energy consumers in airport terminal buildings.•Six strategies are proposed to reduce energy consumption of terminal buildings.•The effect of the strategies on energy consumption and CO2 emissions are analyzed.•Implementing feasible strategies save considerable energy and reduce emissions.
Shot peening treatment is a well-known and practical method to improve surface properties of materials. In this method, surfaces of materials are peened by small steel shots and thus, surface ...hardening is provided. Although it is used in a wide range of applications, this process could affect the electrochemical behavior of materials because of changing surface properties. Therefore, the effects of shot peening process on the electrochemical properties of a low-alloy steel were examined in the present study. AISI 4140 low-alloy steel samples were shot peened in different intensities of 16 A, 18 A, 20 A and 24 A. Afterwards, corrosion tests were carried out at room temperature in a 3.5% NaCl solution. Open circuit potential (OCP) electrochemical polarization and electrochemical impedance spectroscopy (EIS) analysis were performed in corrosion tests. The microstructural, morphological and surface properties of samples were analyzed by XRD, SEM and 3D surface profilometer. The structural analyses showed that grain structure of the material was affected by shot peening treatment. A plastically deformed zone, which have extended and refined grain structure, formed after shot peening processes. Electrochemical analyses indicated that the corrosion resistance of the material increased with the increasing shot peening intensity owing to grain refinement and formation of sub-grains. Also, examinations on the corroded surfaces showed that crevice corrosion was the main mechanism for shot peened samples.
•AISI 4140 steel was shot peened in different Almen intensities.•The increasing Almen intensity increases the hardness and residual stress.•The corrosion potential is directly proportional with Almen intensity.•Crevice corrosion was the main corrosion mechanism.
•The surfaces of untreated and coated samples are hydrophilic.•The film surface with maximum corrosion resistance for all three of the SBF, DMEM and PBS solutions is Ag doped TiN.•SBF and DMEM showed ...similar performances in short-term experiments, which could be alternatives to each other.•TiN-based films significantly reduce the biodegradation rate of untreated AZ31, both electrochemically and using the immersion corrosion technique.
The biocorrosion phenomenon is an important mechanism that determines the biodegradability capacity. The effectiveness of studies on biodegradable materials is directly proportional to detailed corrosion experiments and analysis of formation mechanisms. In this context, experiments and analyzes have also become frequently used for magnesium alloys. In this study, TiN-based coatings were applied by physical vapor deposition method to tailor AZ31 alloy suitable for use as temporary implant material. Different in vitro media were used for comprehensive simulation of the biological environment, and material losses were interpreted on the basis of corrosive damage.
The longwall top coal caving (LTCC) production method, applied by forming a face in the horizontal thickness of the seam and also called horizontal section top coal caving, especially in studies ...originating from China, is widely used in the production of inclined and thick coal seams. In this production method, in addition to the top coal losses that occur behind the face in the traditional LTCC production method, and top coal loss zone occurs above the tail part of the face. Here, the caving height is an effective parameter in the top coal losses occurring behind the face and on the tail part of the face, and in this study, the effect of caving height on the efficiency of the LTCC method applied in inclined and thick coal seams was investigated. In the study, a physical model was used, which was tested with field data and achieved a minimum success rate of 93.4% in the test parameters. In order to determine the effect of the caving height on the efficiency of the LTCC method, a total of 15 tests were performed with the physical model in 3 different seam slopes. As a result of the tests, it was determined that the amount of top coal and waste rock drawn and top coal loss increased with the increase in the caving height value. On the other hand, it was determined that the rock mixture ratio first decreased and then increased with the increase in the caving height value. In addition, the flow angle of the top coal was determined as an average of 74.9° in the coal loss zone between the top coal and the floor and 73.4° on the gob.
•Importance of caving height in LTCC applied in steeply inclined thick coal seams.•Applicability of physical modeling as research method.•Compatibility of the physical model with the field data.•Importance of coal seam slope and thickness in LTCC applications.•Effects of caving height on top coal loss and rock mixture ratio.
Graphene platelets (GPLs) containing Al2O3 nanocomposites, which exhibit anisotropic microstructure, have been prepared by spark plasma sintering (SPS), and effects of this anisotropy on mechanical, ...electrical and thermal properties of the nanocomposites have been investigated. 3vol.% GPLs addition into monolithic Al2O3 caused fracture toughness (Kıc) to increase by 26.7% in the in-plane direction and to decrease by 17.2% in the through thickness direction. Kıc started to decrease in the in-plane direction and to increase in the through-thickness direction with further increase in the GPLs amount. The electrical conductivity of the nanocomposites exhibited a slight anisotropy with a lower resistivity in the in-plane direction. Oriented GPLs also led to a less resistive heat conduction path in the in-plane direction. ∼44% increase in the in-plane thermal conductivity was achieved at 600°C with 15vol.% GPLs addition into the monolithic Al2O3 and this resulted in ∼52% increase in the kin-plane/kthrough-thickness ratio.
This study aims to investigate the effects of duplex surface treatment consisting of plasma nitriding and DLC coating on the fatigue properties of Ti6A4V alloy. For this investigation, Ti6Al4V ...samples were plasma nitrided at 650 °C, 700 °C and 750 °C for 1, 2 and 4 h and then DLC films were produced on the plasma nitrided samples. The structural, mechanical and morphological features of the samples were characterized by XRD, SEM, micro hardness tester and scratch tester. Fatigue tests were performed on the samples by using stress life method. On the surface and sub-surface of the samples, a compound layer and a diffusion zone were formed by plasma nitriding, respectively and XRD results revealed that these layers consisted of Ti2N and TiN phases. The raising process time and temperature caused to increase the thickness of these layers and they also increased the surface hardness of the samples. On the other hand, DLC coated samples exhibited more surface hardness than untreated and all the plasma nitrided samples. Fatigue analyses revealed that plasma nitriding reduced the fatigue strength of the material in all process conditions. Although plasma nitriding formed hard surface and sub-surface layers, the brittle structure of the layers and the great difference of elastic modulus between the substrate and nitride layers caused to decrease the fatigue strength of the material. Although DLC coating increased the fatigue strength of untreated and plasma nitrided samples at 650 °C for 1 h, 700 °C and 750 °C for 4 h), the fatigue strength of duplex treated samples (plasma nitrided at 650 °C for 1 h, 700 °C and 750 °C for 4 h and DLC coated) was lower than the fatigue strength of untreated material, similar to only plasma nitrided materials. This showed that the fatigue strength of duplex treated Ti6Al4V was controlled by plasma nitriding.
•Ti6Al4V alloy was plasma nitrided at different temperatures and times.•DLC films were produced on untreated and plasma nitrided samples.•A reduction was observed in the fatigue strength of the material after plasma nitriding.•DLC films produced on untreated and plasma nitrided samples improved the fatigue strength of the material.
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