Pure Air Research Articles

Laminar burning velocity, emissions, and flame structure of dimethyl ether-hydrogen air mixtures

The present work reports experimentation and numerical simulations of laminar burning velocity, emission analysis, and flame structure of dimethyl ether-hydrogen mixtures. The volumetric hydrogen addition is considered into the DME fuel for a range of mixture equivalence ratios (0.6<ϕ < 1.7). The initial mixture temperature is raised to 373 K at constant atmospheric pressure of 1.0 bar. The heat flux method is utilized to investigate the laminar burning velocity in laminar premixed planar adiabatic flames. The laminar burning velocity (LBV), along with the flame position and emission measurements, are extracted from these flames. The computations were performed with freely propagating flames (LBV, species, sensitivity, etc. data), and the burner stabilizes flames (flame position and emission analysis) for the same mixture and initial conditions using various detailed mechanisms. An emphasis is paid to a newly developed Shrestha mechanism, which includes a radiation model and NO sub-mechanism. Both experimental data and competition results were validated against the pure DME air mixture data available in the existing literature, and further analysis was carried out. It is observed that planar flames can be stabilized only up to a hydrogen addition of 40%. Adding hydrogen enhanced the flame temperature, heat release rates, and burning velocity while reducing the CO and NO emissions. A slight shift of peak burning velocity on the rich side of the equivalence ratio (from 1.05 to 1.2) is observed with hydrogen addition (0–40%). The mixture temperature also enhances the flame temperature and laminar burning velocity. It is interesting to note that hydrogen-added mixtures show a relatively lower dependency on initial mixture temperature. The variation of dominant species and heat release rates are also discussed in detail. The sensitivity analysis is carried out to get information on dominant reactions participating in the combustion of DME hydrogen mixtures.

Community adaptive capacity to drought in Kakap Springs catchment area

Water in karst areas flows deep below the surface due to geological causes, making it difficult to get pure air on the surface. The karst region has passed with drought as a result. In the watershed Kakap Springs, this paper will examine the adaptability of the community to drought. The study area covers seven villages. The evaluation uses a quantitative descriptive method based on human, social, natural, physical, and financial factors. Adaptation capacity in the research area varies with the driving factor is financial. This is because exposure to drought has been going on for a long time and every year, so people have prepared themselves financially. Intensive exposure also causes the distribution of adaptive capacity in each village to be regulated at a moderate level. It is necessary to increase social capacity so that the adaptive capacity of the community becomes higher.

Sulfone‐Modified Covalent Organic Frameworks Enabling Efficient Photocatalytic Hydrogen Peroxide Generation via One‐Step Two‐Electron O2 Reduction

AbstractPhotocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H2O2) synthetic strategy, especially the one‐step two‐electron (2e−) ORR route holds great potential in achieving highly efficient and selectivity. However, efficient one‐step 2e− ORR is rarely harvested and the underlying mechanism for regulating the ORR pathways remains greatly obscure. Here, by loading sulfone units into covalent organic frameworks (FS‐COFs), we present an efficient photocatalyst for H2O2 generation via one‐step 2e− ORR from pure water and air. Under visible light irradiation, FS‐COFs exert a superb H2O2 yield of 3904.2 μmol h−1 g−1, outperforming most reported metal‐free catalysts under similar conditions. Experimental and theoretical investigation reveals that the sulfone units accelerate the separation of photoinduced electron‐hole (e−‐h+) pairs, enhance the protonation of COFs, and promote O2 adsorption in the Yeager‐type, which jointly alters the reaction process from two‐step 2e− ORR to the one‐step one, thereby achieving efficient H2O2 generation with high selectivity.

Sulfone-Modified Covalent Organic Frameworks Enabling Efficient Photocatalytic Hydrogen Peroxide Generation via One-Step Two-Electron O2 Reduction.

Photocatalytic oxygen reduction reaction (ORR) offers a promising hydrogen peroxide (H2 O2 ) synthetic strategy, especially the one-step two-electron (2e- ) ORR route holds great potential in achieving highly efficient and selectivity. However, efficient one-step 2e- ORR is rarely harvested and the underlying mechanism for regulating the ORR pathways remains greatly obscure. Here, by loading sulfone units into covalent organic frameworks (FS-COFs), we present an efficient photocatalyst for H2 O2 generation via one-step 2e- ORR from pure water and air. Under visible light irradiation, FS-COFs exert a superb H2 O2 yield of 3904.2 μmol h-1 g-1 , outperforming most reported metal-free catalysts under similar conditions. Experimental and theoretical investigation reveals that the sulfone units accelerate the separation of photoinduced electron-hole (e- -h+ ) pairs, enhance the protonation of COFs, and promote O2 adsorption in the Yeager-type, which jointly alters the reaction process from two-step 2e- ORR to the one-step one, thereby achieving efficient H2 O2 generation with high selectivity.

Aerosols, airflow, and more: examining the interaction of speech and the physical environment.

We describe ongoing efforts to better understand the interaction of spoken languages and their physical environments. We begin by briefly surveying research suggesting that languages evolve in ways that are influenced by the physical characteristics of their environments, however the primary focus is on the converse issue: how speech affects the physical environment. We discuss the speech-based production of airflow and aerosol particles that are buoyant in ambient air, based on some of the results in the literature. Most critically, we demonstrate a novel method used to capture aerosol, airflow, and acoustic data simultaneously. This method captures airflow data via a pneumotachograph and aerosol data via an electrical particle impactor. The data are collected underneath a laminar flow hood while participants breathe pure air, thereby eliminating background aerosol particles and isolating those produced during speech. Given the capabilities of the electrical particle impactor, which has not previously been used to analyze speech-based aerosols, the method allows for the detection of aerosol particles at temporal and physical resolutions exceeding those evident in the literature, even enabling the isolation of the role of individual sound types in the production of aerosols. The aerosols detected via this method range in size from 70 nanometers to 10 micrometers in diameter. Such aerosol particles are capable of hosting airborne pathogens. We discuss how this approach could ultimately yield data that are relevant to airborne disease transmission and offer preliminary results that illustrate such relevance. The method described can help uncover the actual articulatory gestures that generate aerosol emissions, as exemplified here through a discussion focused on plosive aspiration and vocal cord vibration. The results we describe illustrate in new ways the unseen and unheard ways in which spoken languages interact with their physical environments.

IoT Based Air Quality Monitoring System Using Arduino

In this work, Internet of Things (IoT) system has been devised to monitor in real time the basic pollutants like Carbon dioxide, Carbon monoxide, Particulate matter, Temperature, Humidity, Pressure. The Primary focus of this paper is to monitor air quality at indoor and outdoor level of residential and industrial sectors by using in total of five sensors, ESP8266 Wi-Fi module and Arduino Uno. The emission from vehicle modeling and vehicle’s other emissions can be monitored easily through the internet. A real time air quality monitoring system is essential for Bangladesh especially in Dhaka City because, here the pure air is getting denser and polluted day by day. All sensors real-time data will be displayed on LCD and only the humidity and temperature will be shown on the server. With the help of this project, we have been able to take real-time data of the North and the South side of Dhaka city in February 2023 and plotted curves in Excel. After the analysis of output curves from the Excel plots, we found out our air is very polluted and getting thicker day by day.

Efficacy of the parasitic wasp, Dinarmus basalis Rondani (Hymenoptera: Pteromalidae), in reducing infestations by the cowpea beetle, Callosobruchus maculatus (L.) (Coleoptera: Chrysomelidae: Bruchinae)

BackgroundCowpea seed beetle, Callosobruchus maculatus (L.) (Coleoptera: Chrysomelidae: Bruchinae), is the most important pest of stored cowpea in tropical regions. This study was designed to determine the presence of parasitoids associated with C. maculatus, investigate the efficacy of the parasitic wasp, Dinarmus basalis Rondani (Hymenoptera: Pteromalidae), in controlling C. maculatus as influenced by time and number of applications and ascertain the use of olfactory cues by D. basalis in host searching. Three markets in Ibadan, Southwest Nigeria, namely: Bodija, Mapo and Ojoo, were purposively surveyed for parasitoids associated with C. maculatus. Two pairs of D. basalis were released at 3-day intervals into cowpea seeds previously infested with C. maculatus. Treatments included: four times of parasitoid applications (4-TPA), three applications (3-TPA), two applications (2-TPA), 1 application (1-TPA) and a control without parasitoid application (0-TPA). All treatments were replicated four times in a completely randomized design to determine F1 progeny of C. maculatus and seed damage. Olfactory bioassay was carried out with D. basalis adults placed in a Y-tube olfactometer; and their preference for infested or uninfested three cowpea varieties, namely: Ife Brown, Ife BPC (Branching Peduncle) and Oloyin, as well as infested cowpea grains or pure air was evaluated.ResultsAmong the previously known parasitoids associated with C. maculatus, only D. basalis was found in the sampled markets. F1 progeny of adult C. maculatus reduced from 4.75 individuals (0-TPA) to 1.25 (2-TPA), 0.25 (3-TPA) and 0 (4-TPA). Concurrently, the number of exit holes on cowpea seeds significantly (p < 0.05) ranged from 5.25 (0-TPA) > 3.21 (1-TPA) > 2.20 (2-TPA) > 2.18 (4-RAP) > 1.39 (3-TPA). Adults D. basalis were more attracted to infested grains of Ife Brown (χ2 = 4, df = 1, p = 0.0455) and infested grains of Ife BPC (χ2 = 4, df = 1, p = 0.0455) than clean air. Similarly, adults D. basalis were more attracted to infested Ife Brown than the uninfested (χ2 = 5, df = 1, p = 0.0254). The results further showed that there were non-significant differences between the infested and uninfested grains of Ife BPC (χ2 = 0.2, df = 1, p = 0.6547) and Oloyin (χ2 = 3.2, df = 1, p = 0.0736) varieties.ConclusionsAdult D. basalis reduced emergence of C maculatus and reduced damage in cowpea seeds. Olfactory cues played a necessary role in host-searching efforts of D. basalis.

Multi-scalar mixing in turbulent coaxial jets

Although natural and industrial flows often transport and mix multiple scalars, relatively few studies of turbulent multi-scalar mixing have been undertaken. In the present work, a novel three-wire thermal-anemometry-based probe – capable of simultaneously measuring velocity, helium concentration and temperature – is used to investigate the evolution of multiple scalars ($\phi _1$,$\phi _2$,$\phi _3$) and velocity in turbulent coaxial jets. The jets consist of (i) a centre jet containing a mixture of helium and air ($\phi _1$), (ii) an annular jet containing pure (unheated) air ($\phi _2$) and (iii) a coflow of (pure) heated air ($\phi _3$). Axial measurements are made at three different momentum flux ratios ($M=0.77, 2.1, 4.2$). Increasing$M$was observed to result in complex, competing effects. Larger momentum flux ratios cause the potential core of the centre jet to decrease in size, greater scalar fluctuations and more rapid correlation of$\phi _1$and$\phi _2$. However, at the same time, certain statistics, including those describing the velocity field, evolve more slowly. Moreover, the flow near the beginning of the fully merged region appears to be less mixed at higher values of$M$. The present work finally demonstrates that differences can be observed in the evolution and mixing of coaxial jets between those in which$M&lt;1$and those in which$M&gt;1$, thereby presenting an opportunity by which the mixing process in coaxial jets may be controlled.

Influence of Screening Electrode on Surface Flashover in Atmospheric Environment

The surface flashover at atmospheric pressure is the main factor that limits the insulation performance of high-voltage devices. In order to rise the dielectric strength of the surface, the screening electrode is frequently used. In this article, the characteristics of the flashover on the ceramic surface are studied by experiments in air with different structures of the screening electrode. The effect of the screening electrode on dielectric strength is obtained by comparing the breakdown voltage of the ceramic surface with screening electrode with that of the pure air gap and ceramic surface. Besides, the evolution of the plasma under different lengths of the screening electrode is captured by a high-speed camera, and the transformation of the gas discharge to surface flashover with the decreasing shield length is observed. The competition between the two processes is discussed. The result provided a straight view and deeper understanding of the effect of the screening electrode.

Randomized, placebo-controlled study on efficacy, safety and tolerability of drug-induced defibrinogenation for sudden sensorineural hearing loss: the lessons learned

PurposeDisturbance of cochlear microcirculation is discussed as final common pathway of various inner ear diseases. Hyperfibrinogenemia causing increased plasma viscosity is a possible factor for a critical reduction of cochlear blood flow that might lead to sudden sensorineural hearing loss (SSHL). The aim was to determine the efficacy and safety of drug-induced defibrinogenation by ancrod for SSHL.MethodsDouble-blind, randomized, placebo-controlled, multicenter, parallel group, phase II (proof-of-concept) study (planned enrollment: 99 patients). Patients received an infusion of ancrod or placebo (day 1) followed by subcutaneous administrations (day 2, 4, 6). Primary outcome was the change in pure tone audiogram air conduction average until day 8.ResultsThe study was terminated early due to slow recruiting (31 enrolled patients: 22 ancrod, 9 placebo). A significant improvement of hearing loss was registered in both groups (ancrod: − 14.3 dB ± 20.4 dB, − 39.9% ± 50.4%; placebo: − 22.3 dB ± 13.7 dB, − 59.1% ± 38.0%). A statistically significant group-difference was not detected (p = 0.374). Placebo response of 33.3% complete and 85.7% at least partial recovery was observed. Plasma fibrinogen levels were reduced significantly by ancrod (baseline: 325.2 mg/dL, day 2: 107.2 mg/dL). Ancrod was tolerated well, no adverse drug reaction was of severe intensity, no serious adverse events occurred.ConclusionAncrod reduced fibrinogen levels that support its mechanism of action. The safety profile can be rated positively. Since the planned number of patients could not be enrolled, no efficacy conclusion can be drawn. The high rate of placebo response challenges clinical trials for SSHL and needs to be considered in future investigations.Trial registrationsThis study was registered in the EU Clinical Trials Register, EudraCT-No. 2012-000066-37 at 2012-07-02.

Numerical investigations of the nozzle performance for a rocket-based rotating detonation engine with film cooling

This study numerically investigates the nozzle performance of a rotating detonation engine with film cooling. The premixed stoichiometric hydrogen/air mixture serves as the reactant, and the pure air is pumped into the film cooling holes. The diverging section of the nozzle is designed based on the characteristic method and the maximum thrust theory. The spike truncation ratio is optimized to ΔLspike = 40% Lcowl, reducing the weight and maintaining a high axial thrust coefficient of 0.9456. In contrast with the steady condition, the flow loss of the practically transient condition mainly comes from three parts. The first is the pressure loss of the continuously sweeping shock waves, the second is the viscous effect of the flow passage, and the third is the energy dissipation of the recirculation zone in the base region. When the film cooling strategies are introduced on the inner and outer walls, the hole type a/b < 1.0/1.0 is preferred thanks to a more considerable coolant coverage induced by more violent interactions between the radial jet and the mainstream. The cooling effects and the aerodynamic performance can be further balanced within a moderate injection velocity. The final optimized nozzle configuration with ΔLspike = 40% Lcowl, a/b = 1.0/2.0, and Vsec = 100 m/s corresponds to an axial thrust coefficient of 0.9552, a discharge coefficient of 0.9344, a pressure gain of -16.48%, and a root mean square deviation of the flow deflection angle of 14.42°.

Pneumatic Retinopexy Involving the Use of Intravitreal Air Injection and Laser Photocoagulation for Rhegmatogenous Retinal Detachment in Phakic Eyes

The clinical efficacy of pneumatic retinopexy (PR) using intravitreal pure air injection and laser photocoagulation for rhegmatogenous retinal detachment (RRD) remains unknown. Thirty-nine consecutive patients with RRD (39 eyes) were included in this prospective case series. All patients underwent two-step PR surgery containing pure air intravitreal injection and laser photocoagulation retinopexy during hospitalization. The main outcomes were best-corrected visual acuity (BCVA) and primary anatomic success rates after PR treatment. The mean follow-up was 18.3 ± 9.7 months, ranging from 6 to 37 months. The primary anatomic success rate was 89.7% (35/39) after PR treatment. Final reattachment of the retina was achieved in 100% of cases. Macular epiretinal membrane was developed in two patients (5.7%) among successful PR cases during the follow-up. The mean logMAR BCVA value was significantly improved from 0.94 ± 0.69 before surgery to 0.39 ± 0.41 after surgery. The average central retinal thickness was significantly thinner in the RRD eyes of macula-off patients (206.8 ± 56.13 μm) when compared with the fellow eyes (234.6 ± 48.4 μm) at the last follow-up (p = 0.005). This study concluded that an inpatient PR procedure with pure air injection and laser photocoagulation is a safe and effective approach to treating patients with RRD, who may achieve a high single-operation success rate and good visual acuity recovery.

Laboratory Evidence of 2-Isobutyl-3-methoxypyrazine as a Male-Released Aggregative Cue in Labidostomis lusitanica (Germar) (Coleoptera: Chrysomelidae).

In spite of its incidence on pistachio trees, the chemical ecology of Labidostomis lusitanica (Germar) (Coleoptera: Chrysomelidae) has been neglected so far. In this work, we provide the first evidence of a biologically active male-specific compound that may be promoting field aggregation. Headspace collections through solid-phase microextraction from feral males and females reported the presence of 2-isobutyl-3-methoxypyrazine exclusively in males. Electroantennographic recordings revealed that males and females responded in a dose-dependent manner to increasing stimuli of 2-isobutyl-3-methoxypyrazine, with females overall displaying a higher response than males. In dual-choice tests, both males and females showed a significant preference for the compound in comparison to a pure air stimulus. In light of these results, the possible role of 2-isobutyl-3-methoxypyrazine as an aggregation cue in L. lusitanica is discussed.

Impacts of operating conditions on the recovery of proton exchange membrane fuel cells exposed to sulfur dioxide in an air stream

Airborne SO2 contaminants compromise the performance of proton exchange membrane fuel cells (PEMFCs) due to the formation of strongly adsorbed S-containing species, mainly S0, on the cathode Pt surface and a lack of self-recovery in pure air. To restore PEMFC performance, we applied voltage cycling from 0.1 to 1.2 V vs. the potential at the anode and with the H2/N2 gas configuration. This induced cyclic voltammetry (CV) procedure was examined for PEMFC performance recovery after 13–14 h of cathode exposure to 5 ppm SO2 under different conditions. It was determined that the efficiency of CV-induced recovery depended on the operating temperature and current during contamination. The method recovered 99% of the performance after exposure to SO2 at 60 °C and a constant current of 0.6 A cm−2. An increase in the operating current and cell temperature favored the formation of strongly bonded S0 and catalyst degradation, so the performance recovery reached 95% for 60 °C and 1.0 A cm−2, 90% for 80 °C and 0.6 A cm−2, and 84% for 80 °C and 1.0 A cm−2. The PEMFC performance after exposure to SO2 at high temperature could not be fully recovered by the CV-induced method and seemed to require additional or modified procedures.

ITO Thin Films for Low-Resistance Gas Sensors.

Indium tin oxide thin films were deposited by magnetron sputtering on ceramic aluminum nitride substrates and were annealed at temperatures of 500 °C and 600 °C. The structural, optical, electrically conductive and gas-sensitive properties of indium tin oxide thin films were studied. The possibility of developing sensors with low nominal resistance and relatively high sensitivity to gases was shown. The resistance of indium tin oxide thin films annealed at 500 °C in pure dry air did not exceed 350 Ohms and dropped by about 2 times when increasing the annealing temperature to 100 °C. Indium tin oxide thin films annealed at 500 °C were characterized by high sensitivity to gases. The maximum responses to 2000 ppm hydrogen, 1000 ppm ammonia and 100 ppm nitrogen dioxide for these films were 2.21 arbitrary units, 2.39 arbitrary units and 2.14 arbitrary units at operating temperatures of 400 °C, 350 °C and 350 °C, respectively. These films were characterized by short response and recovery times. The drift of indium tin oxide thin-film gas-sensitive characteristics during cyclic exposure to reducing gases did not exceed 1%. A qualitative model of the sensory effect is proposed.

Investigation of effects of sand particles on aerodynamic performance of NACA 0012 airfoil

The purpose of this paper is to study the effects of turbulence kinetic energy structures formed during flow and particles of different diameters and different flow velocities in the air in different regional areas on aerodynamic performance characteristics in NACA 0012. Single and two phase fluid flows were worked out by using Ansys Fluent Computational Fluid Dynamics (CFD) code. Computational results obtained from Ansys Fluent CFD code for pure air and the air containing sand particles were compared with numerical values gained in the literature for validation. Results obtained from the numerical tests demonstrate good agreement with the value in the literature. These results indicate the turbulence kinetic energy value occurred in the tail region of the airfoil increases with the increase in the angle of attack and shifts towards the upper region of the airfoil at high attack angle. Moreover, the upper region of the airfoil at high attack angle becomes larger at low Reynolds numbers due to viscous effects. The drag and lift coefficients obtained in the numerical tests of the airfoils and in the experimental tests in the wind tunnel will differ from the values in the application area. Because, in the operation of airfoils in different regional environments, there are always particles of various concentrations and diameters in the air. In this case, the drag coefficient increases and the lift coefficient decreases.

Hydrogen Sensors Based on In2O3 Thin Films with Bimetallic Pt/Pd Catalysts on the Surface and Tin and Dysprosium Impurities in the Bulk

This paper presents the results of studying the characteristics of hydrogen sensors based on thin In2O3 films modified with tin and dysprosium with dispersed double Pt/Pd catalysts deposited on the surface. To control the content of Sn and Dy in the films, an original technology was developed, and ceramic targets were fabricated from powders of the In–Dy–O, Dy–Sn–O, and In–Dy–Sn–O systems synthesized by the sol–gel method. Films of complex composition were obtained by RF magnetron sputtering of the corresponding targets. Structural features of the obtained thin films were studied by Raman spectroscopy. It is shown that various combinations of tin and dysprosium concentrations, as well as the presence of Pt/Pd catalysts on the surface, have a significant effect on the defectiveness of the films and the density of oxygen adsorption centers. As a result, the resistance of sensors in pure air (R0), the activation energies of the temperature dependences of R0, the bending of the energy bands at the grain boundaries of the semiconductor, and the responses to the action of hydrogen in the concentration range of 20–25,000 ppm change. A unique feature of Pt/Pd/ In2O3: Sn (0.5 at%), Dy (4.95 at%) films is their high sensitivity at 20–100 ppm and the absence of signal saturation in the region of high hydrogen concentrations of 5000–25,000 ppm, allowing them to be used to detect H2 in a wide range of concentrations.

Combustion and Emission Characteristics of CNG-Diesel Dual Fuel Engine with Variation of Air Fuel Ratio

Compressed natural gas (CNG) is a popular alternative fuel because of its more environmentally friendly properties than fossil fuels , including applications in diesel engines. However, supplying too much compressed natural gas fuel causes poor engine performance and emissions due to a decrease in the air-fuel ratio on the dual-fuel engine. The addition of air using electric superchargers was done to return the air-fuel ratio to ideal conditions. Lambda value (λ) was variation under low load (1.52 to 2.71), medium load (1.18 to 2.17), and high load (0.94 to 2.17) on a CNG-diesel dual fuel engine. The addition of pure air in each load can increase combustion stability in certain lambda, which was indicated by an increase in thermal efficiency, heat release rate, and a decrease in ignition delay, combustion duration, hydrocarbon, and carbon monoxide emissions.

One Acute Exposure to E-Cigarette Smoke Using Various Heating Elements and Power Levels Induces Pulmonary Inflammation.

Electronic cigarettes (eC) may not be entirely benign. There is a lack of data on the effect of a single acute exposure of eC vapor using various heating sources and power settings upon lung injury. The purpose of this study was to determine if an acute exposure with eC vapor heated with different heating elements and power levels induced inflammatory changes in the lungs and heart. Rats were exposed to pure air or received a single, 4-h exposure to eC vapor. The devices used either a stainless steel (SS) or nichrome (NC) heating element randomized to a low or high atomization power (45 versus 70 W). Rats were euthanized within 48 h of exposure. The eC groups showed accumulation of inflammatory cells in bronchial lumen, near the pleura, and within the alveolar spaces. The numbers of inflammatory cells per field in the lung parenchyma were significantly greater in the rats exposed to eC groups vs. the air group. There were significantly higher inflammatory gene expression changes in the lungs of animals assigned to 70 W power. We observed that eC vapor generated using burnt coils were toxic and could cause acute respiratory distress and myocarditis. In conclusion, one 4-h exposure to eC vapor, in the absence of vitamin E oil or nicotine, significantly increased lung inflammation. Effects were seen after exposures to vapor generated using SS and NC heating elements at either high or low power. Vapor from devices with burnt coils can negatively affect the heart and lung.

RILEM TC 277-LHS report: lime-based mortars for restoration–a review on long-term durability aspects and experience from practice

For conservation interventions of historic masonry generally lime-based mortars such as pure air lime mortars, lime-pozzolan mortars, natural hydraulic lime mortars and ternary mortars (lime-pozzolan-cement) are used. The main reason is that their hygric and mechanical (strength and ductility) performance are easy to adapt to most existing historic masonry (compatibility requirements). Although the basic appropriateness of lime-based mortars for restoration is undisputed, there are also some limitations in the application of these mortars. In this report a review is given of the theoretical backgrounds and further of laboratory research developments in the field of lime-based binders and mortars over the past decades. Furthermore, practical experiences in positive and negative sense (damage cases) are elaborated. Drawbacks and points of attention are being dealt with, which are essential for a durable application of lime-based mortars for the conservation of historic masonry. In general, it is concluded that points of attention should be addressed through a thorough evaluation of their potential and through testing of their suitability. For these mortars, even more than for modern cement-based mortars, specifically, environmental exposure conditions and application conditions should be considered.