Pulp Temperature Research Articles

Hydrotropic Pulping of Miscanthus to Obtain Pulp

The hydrotropic pulping of crushed straw of Miscanthus sacchariflorus Andersson to produce pulp was studied herein. A concentrated sodium benzoate solution was used as the reagent. Established regularities of the pulping temperature and time effects on delignification quality attributes such as pulp yield and residual lignin content in the pulp. The generalized arithmetic-mean optimization parameter enabled hydrotropic pulping optimum conditions to be identified to obtain hard pulp fit. Experimentally displayed the possibility of using cellulose for the manufacture of special paper grades

Temperature variations in pulp chamber: an in-vitro comparison between ultrasonic and rotating instruments in tooth preparation. Part 1.

The purpose of this study was to analyze pulpal temperature increase generated by prosthodontic margin repositioning and finishing with ultrasonic and rotating instruments. The temperature changes recorded were also correlated with the residual dentin thickness. A sample of 32 human extracted molars was selected. The teeth were endodontically treated and prepared with prosthetic round chamfer preparation. Then, they were inserted in plaster cubes up to the cement-enamel junction, leaving the apical portion pervious for inserting the thermocouple probe. The conventional technique, which involves the use of a high-speed contra-angle handpiece, was compared with an ultrasonic method (Crown Prep, Mectron, Carasco, Italy). For margin repositioning and finishing, two walls were randomly selected for each tooth: one was included in the test group and cut with the piezoelectric instrument (Multipiezo Touch TipHolder DB2, Mectron, Carasco, Genoa, Italy), the other one was inserted in the control group and cut with the high speed contra-angle handpiece (Kavo, Biberach, Germany). To standardize the operator-dependent parameters, it was used a mechanical arm controlled by a computer. These parameters were the pressure exerted on the dental wall, the cutting length and the time required for margin repositioning and finishing. For both test and control group, test phase consisted in a first stage of margin repositioning using an ultrasound tip or a diamond bur with a greater granulometry (120 µm for the ultrasound tip and 125 µm for the diamond bur), followed by a second finishing step conducted by an ultrasound tip or a diamond bur with smaller granulometry (60 µm for the ultrasound tip and 30 µm for the diamond bur). During these stages the intrapulpal temperature was recorded thanks to a thermocouple. Before and after these steps, the thickness of the remaining dental walls was measured with a caliber. The average pulpal temperature increase was 5.03±0.98 °C for the ultrasonic preparation (test group) and 3.55±0.95 °C for the conventional technique (control group). The difference was statistically significant (P value <0.001). However, neither of the instruments reached the critical level of 5.5 °C reported in the literature. The mean initial dentin thicknesses was 1.82±0.47 mm for the control group and 1.59±0.54 mm for the test group but the analysis of the residual dentin thicknesses revealed a greater reduction of the walls worked up with high speed contra-angle handpiece (mean 0.9±0.5 mm), which was therefore more aggressive than the ultrasonic instrument (mean 1.1±0.5 mm). A very weak negative correlation was present between the thickness of the wall at baseline and the increment of temperature. Within limitations of this study, temperature increasing of ultrasonic instruments shows a statistical difference related to rotary ones. But, as literature shows, the ultrasonic advantages are margin precision, preservation of soft tissues and reduction of operating times. Furthermore, in relation with results of this study, they could be considered safe for pulp vitality because the increase in pulpal temperature is similar to traditional instruments and it does not exceed the critical level of 5.5 °C.

A Novel Method for Improving Low-Temperature Flotation Performance of Nonpolar Oil in the Molybdenite Flotation

Nonpolar hydrocarbon oil (NHO) is one of the most extensively used collectors in the flotation of molybdenite due to its excellent selectivity. However, NHO has low sensibility at pulp temperature. At low temperatures (&lt;283 K), although more kerosene is used, the recovery of molybdenite flotation is still lower than at room temperature. In this study, magnetizing treatment, which is an efficient, low-cost, innovative, and environmentally friendly emulsification method, was used to improve the flotation performance of NHO in low-temperature molybdenite flotation. The test results showed that, compared with unmagnetized kerosene (UMK), the optimum dosage of magnetized kerosene (MK) could be reduced by 11% at 298 K. At the same dosage of kerosene, the flotation recovery of MK was 3% higher than UMK at 278 K. The surface tension measurement results showed that the surface tension of MK rose periodically as the magnetic field intensity increased, and there was a maximum surface tension within each period. Further, the magnetic field intensity had the maximum flotation recovery of molybdenite at the maximum surface tension of MK. Combined with the analysis based on the Girifalco–Good theory and the static drop volume method of interfacial tension, the interfacial tension of kerosene–water was shown to decrease with the increase of the surface tension of kerosene. This finding indicates that the dispersibility of kerosene in pulp could be improved by reducing the size of oil droplets, thereby improving the molybdenite flotation recovery of kerosene at low-temperature pulp. It is helpful to improve the flotation recovery of molybdenite using NHO as a collector for low-temperature pulp (&lt;283 K).

Digital twins probe into food cooling and biochemical quality changes for reducing losses in refrigerated supply chains

Refrigerated transport and storage of mango fruit are essential to maintain quality, reduce food waste and the associated embodied energy losses. Refrigeration is also key to enable successful transcontinental export to distant markets. To minimize the environmental impact of the cold chain and to optimize logistics, a better knowledge of the fruit quality evolution within individual shipments would be extremely valueable. For this purpose, a digital fruit twin is developed, based on mechanistic modeling. This digital twin simulates the thermal behavior of mango fruit throughout the cold chain, based on the measured environmental temperature conditions, namely the air temperature in the vicinity of the fruit. At the same time, the evolution of associated quality attributes, due to enzymatically-driven, temperature-dependent biochemical degradation reactions, is quantified. Also, a biophysical counterpart of real mango fruit – an innovative fruit simulator sensing device – was developed and used for model validation of fruit pulp temperatures. We identified – in-silico – the impact of the unique delivery air temperature history and cold chain length on fruit quality evolution for actual maritime vs. airfreight transport pathways. Digital twins were found to provide complementary insights in the thermophysical behavior of fruit, particularly in supply chains of very perishable species, and for storage at low airflow rates. Such mechanistic modeling enabled to understand, record, and predict where temperature-dependent fruit quality loss occurs in each supply chain. In that way, digital twins can help to improve refrigeration processes and logistics to reduce food losses, thereby making the refrigerated supply chain greener.

The cooling efficiency of different dental high-speed handpiece coolant port designs

The study investigated the cooling efficiency of different numbers of water coolant ports on high-speed handpieces (HSH) under cooling conditions used in clinical practice.Twenty-four groove cuts with water on and nine cuts without water were made on extracted human premolars using three HSHs with different port configurations. Thermocouples were placed in the pulp chambers and temperature changes were recorded with 1-, 3- and 4-coolant port handpieces. Cooling rate was calculated for each coolant port design system. Temperature changes were statistically analysed with Kruskal-Willis Test.All three sample groups resulted in a net temperature decrease during the cutting period with water turned on. There was a pattern of increased cooling rate with increasing number of coolant ports (1-port: -4.27 (±0.94) °C, 3-port: -4.66 (±2.90) °C, 4-port: -5.03 (±1.08) °C). The difference was not statistically significant (p = 0.681). Calculations of cooling rate showed a higher cooling rate with an increase in the number of ports (1-port: 46.13 × 10−4 K−1, 3-port: 51.36 × 10−4 K−1, 4-port: 56.32 × 10−4 K−1). In the dry tooth preparation samples, all resulted in a net increase in temperature (1-port: 4.43 (±3.30) °C, 3-port: 5.13 (±3.27) °C, 4-port: 2.87 (±2.97) °C).All the three water coolant port configurations showed effective cooling of the tooth during cutting and decreased pulpal temperature with no statistical difference. There are HSH designs with varying numbers of coolant ports available in the market for clinicians. The results of the current study could potentially aid clinicians in making a decision while choosing between different dental handpieces.

Development of a Kinetic Model of the Bacterial Dissolution of Copper Concentrate

The present study introduces a new approach to understand the copper dissolution rate and to find an adapted mathematical statement for particle shrinkage rate in a batch bioleaching system. Four size classes of a chalcopyrite concentrate, namely [D1 : (−54 + 44)μm, D2 : (−44 + 38)μm, D3 : (−38 + 25)μm and D4 : (−25)μm], were used in the batch bioleaching tests by applying a mixed culture of moderately thermophilic microorganisms. The pulp density and temperature were 8 (%w/v) and 50 °C, respectively. Findings delineated that the bioleaching time can be divided into two specific time intervals: first, the surface reactions were the prevailing controlling step; second, the prevailing mechanism was diffusion through the product layer, whereas the overall rate of the process may be related to both through a Q factor using a mixed model. A mathematical model was developed based on particle size distribution (PSD) and a kinetic model. Experimental validation of the mixed model was accomplished by the representative sample with d80 = 54 microns. Results showed that the PSD of the specific sample was in good agreement with Rosin–Rammler function. Besides, the simulation result of the conversion fraction had the best conformity with the experimental data (with a maximum error of approximately 7%). This paper should be considered as an initial part of a larger, global model for chalcopyrite concentrate bioleaching.

Free radicals formation on thermally decomposed biomass

Pyrolysis provides an attractive alternative for the upgrading of agro-wastes to energy and chemicals. However, consistent quality of the final products is still a goal to be achieved at industrial level. The present study aims at complementing existing results recently published by the authors and investigating the physico-chemical evolution and oxidative reactivity of solid products of pyrolysis of citrus waste. Chars derived from slow pyrolysis (50 °C min−1, 200–650 °C peak temperature) of orange and lemon pulp (OP and LP) in a horizontal batch reactor were characterized by means of Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Electron Paramagnetic Resonance (EPR) and Raman spectroscopy. Results show how the onset of breaking of covalent bonds in matrix is triggered by reaching pyrolysis temperatures of 330–350 °C. Around those temperatures, the population of free-radicals significantly increases on solids and chars become more reactive, thereby favoring retrogressive, recombination and secondary solid-vapor reactions. Results also show that the higher content of lignin on LP may facilitate the formation of aromatic networks via lignin fragmentation and condensation above 500 °C. This trend is also confirmed by DSC patterns in which, above 500 °C, significantly more endothermic reactions occur in LP as a comparison to OP. This conclusion is further corroborated by more pronounced G-band Raman shifts shown for LP as a comparison to OP. The present results shed new light on the thermochemical breakdown of solid agro-wastes and provide insights for development of slow pyrolysis technology toward the production of valuable renewable carbonaceous materials.

Temperature change in pulp chamber of primary teeth during curing of coloured compomers: an in vitro study using pulpal blood microcirculation model.

IntroductionAn increase in the temperature of the pulp chamber occurs during polymerisation of all types of light-curing resin-containing restorative materials, due to both the exothermic reaction of the material and the energy absorbed during the curing process. Increase in temperature of the pulp chamber of primary teeth during the curing process or the thermal conductivity properties of coloured compomers (CCs) have not yet been investigated in detail. The aim of the present study was to investigate the increase in pulpal temperature in primary teeth during curing of CCs.Materials and MethodsA Class-II cavity was prepared on the extracted primary mandibular second molar. Pulpal microcirculation of the tooth was performed using an experimental mechanism. The study included 15 groups and 10 experiments in each. Seven different CCs: pink, blue, gold, silver, orange, lemon, green, respectively from two different manufacturers (Groups 1–7: Twinky Star; VOCO, Cuxhaven, Germany. Groups 8–14: Nova Rainbow; IMICRYL, Konya, Turkey.) and a tooth-CC (Group 15: Dyract XP; DENTSPLY, Weybridge, UK.) were applied in prepared cavity. In all groups the compomers were light cured for 40 s. Intrapulpal temperature changes (Δt) in 20th and 40th second were recorded. In Group-15 the Δt values in 10th second were also recorded as per the manufacturer’s instructions. The Kruskal–Wallis test and the Mann–Whitney-U test were used for statistical analyses.ResultsAt the end of 40-s irradiation time, the orange, lemon and green colours of Nova Rainbow resulted in significantly lower Δt values than the same colours of Twinky Star (p = 0.0001), and silver, blue, lemon, green, orange, and pink CCs of Nova Rainbow and the blue and silver shades of Twinky Star demonstrated lower Δt values than the reported critical temperature increase (5.5 °C).ConclusionAn increase in the irradiation time consequently led to an increase in the intrapulpal temperature. Therefore, manufacturers should focus on production of new CCs with shorter polimerization time.

Debonding Time and Dental Pulp Temperature With the Er, Cr: YSGG Laser for Debonding Feldespathic and Lithium Disilicate Veneers.

Introduction: The removal of ceramic veneers is a time-consuming procedure in a dental office. Little research has been done in alternative removal techniques for ceramic veneers. The objective of this study was to evaluate the removal of feldspathic and lithium disilicate reinforced glass ceramic veneers by Er, Cr: YSGG and to measure debonding time and pulpal temperature increase during veneer removal. Methods: Fifty-seven bovine incisor teeth were prepared and divided into 3 groups. Ceramic specimens with a thickness of 0.7mm, a width of 4mm and a length of 8 mm were fabricated from feldspathic ceramic, lithium disilicate reinforced glass ceramic HT (high translucency) and lithium disilicate reinforced glass ceramic MO (medium opacity) (19 for each group). Specimens were cemented on the labial surface of incisors using resin cement. The Er, Cr: YSGG laser was applied to each specimen at 2.5 W and 25 Hz. Debonding time was measured for each specimen, and the intrapulpal temperature was detected in 3 specimens for each group. Data were analyzed via one-way analysis of variance (ANOVA) at significance level of 0.05 (α = 0.05). Results: Mean debonding time was 103.68 (26.76), 106.58 (47.22) and 103.84 (32.90) seconds for feldspathic, lithium disilicate MO, and lithium disilicate HT respectively. There was no significant statistical difference among the groups (P value = 0.96). The intrapulpal temperature increase was less than 1°C in all groups. Conclusion: Er, Cr: YSGG can successfully be used to efficiently debond feldspathic and lithium disilicate reinforced glass ceramic veneers. There was no significant difference for debonding time among these ceramic materials. During ceramic laminate veneer removal by laser irradiation, no irritating temperature rise was detected.

Postharvest methyl bromide fumigation of Japanese plums to control codling moth (Lepidoptera: Tortricidae)

Abstract Postharvest chamber fumigation with 48 mgL−1 (3.0 lbs./1000 ft3) methyl bromide (MB) for 2 h at pulp temperature (T) ≥ 21 °C and chamber load ≤50% is used to control codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in fresh nectarine, Prunus persica (L.) var. nucipersica, and French plum, P. domestica (L.), exports from California USA to Japan. Fumigations were conducted to verify that control of C. pomonella is expected following an analogous fumigation of fresh Japanese plums, P. salicina (Lindl.). A kinetic model, based on temporal measurement of MB levels in chamber headspace and how calculated exposures varied across the fumigation trials, showed that fresh Japanese plums and French plums sorb MB at a statistically equivalent rate, which resulted in an MB exposure ca. 20% higher than that observed for fresh nectarines. Importantly, results from commercial-scale fumigations indicate that pallet shrouds do not influence the efficacy of MB toward C. pomonella eggs, as their presence did not affect the rate of MB sorption, evidence that supports the use of pallet shrouds to safeguard against the potential for post-fumigation infestation in this export scenario, and beyond. Results are discussed in the context of graduation toward optimized quarantine fumigation schedules, which will promote more strategic technical and economic Quarantine Pre-shipment (QPS) uses of MB.

Effect of pulp temperature on separation of magnesite from dolomite in sodium oleate flotation system

Effect of pulp temperature on separation of magnesite from dolomite in sodium oleate flotation system

Alkaline deep eutectic solvent: a novel green solvent for lignocellulose pulping

This work studied the feasibility of potassium carbonate-glycerol deep eutectic solvent (K2CO3-Gly DES) as a potential green solvent applied in lignocellulose pulping. Cellulose fibers were extracted from rice straw via novel alkaline DES pulping technique using 1:7 molar ratio of K2CO3-Gly DES. Optimum pulping parameters were determined using the one-factor-at-a-time (OFAT) method. The cellulose fibers were characterized for chemical composition of cellulose, hemicellulose, lignin and extractives. Changes in physical structure, chemical structure, morphological structure, functional groups and crystallinity index (CrI) were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results revealed that the optimum pulping temperature at 140 °C, reaction time of 100 min and 1:10 rice straw to DES mass ratio produced the highest cellulose content of 73.8% for unbleached DES treated pulp. Chemical composition analysis and FTIR verified that this alkaline DES pulping method was able to achieve partial removal of hemicellulose and lignin from lignocellulosic matrix. Moreover, XRD result demonstrated that the CrI of cellulose fiber increased from 52.8 to 60.0% after pretreatment. The cellulose fibers had diameters ranging from 3.58 to 5.68 µm. This study proved that the specifically-designed K2CO3-Gly DES could successfully isolate cellulose from lignocellulosic biomass through alkaline DES pulping.

On using a new strain of Acidithiobacillus ferridurans for bioleaching of low-grade uranium

ABSTRACTIn the present investigation, isolation and determination of a new strain of Acidithiobacillus ferridurans SBU-SH2 from an Iranian sulfur hot spring are carried out and then it is used to evaluate the performance of uranium bioleaching from a low-grade natural resource host. The efficiency of uranium recovery is studied by considering the influence of experimental factors like pulp density, pH value, temperature, and source of energy. Experimental tests reveal that more than 96% of uranium is recovered at 35°C, initial pH 2.5, agitation speed of 120 rpm, and pulp density of 5% in about 1 week.

Laser Aided Ceramic Restoration Removal: A Comprehensive Review.

Introduction: All-ceramic restorations are being widely used due to its various advantages. However, they have restricted durability and may have to be removed. The conventional procedure for removal is grinding the restoration with rotary instruments which are considered time-consuming and inconvenient. A newer advantageous method is the application of lasers for debonding ceramics from the tooth surface. The objective of this study is to provide a comprehensive literature review on laser-aided ceramic restorations debonding. Methods: We searched PubMed and Google Scholar databases. Seven articles from 2011 to 2018 were identified. Studies were assessed for the efficacy of laser application and the amount of pulpal temperature rise. Results: Studies selected were categorized according to variables including shear bond strength, debonding time and intrapulpal temperature. Oztoprak and Iseri investigated that erbium-doped yttrium, aluminum, and garnet (Er:YAG) laser application reduced shear bond strength of ceramic laminate veneers. The time of debonding took an average of 190 seconds in Rechmann's study and 106 seconds in Morford's study. One of the main issues while using the laser is thermal irritation of the pulp. A 5.5°C temperature increase may cause pulpal damage according to Zach and Cohen. Philips et al and Rechmann et al reported no intrapulpal harm due to temperature increase. Additionally, Phillips et al demonstrated that the laser setting affects both the debonding time and the temperature alterations and that a laser adjustment of 2.5 W/25 Hz would be the best safest group. Conclusion: Removal of ceramic crowns and veneers from tooth surfaces can be successfully done by Er:YAG laser application in a less time-consuming procedure and without any harm to the underlying dentin. However, a temperature rise in the pulp may occur which could be overcome by adequate air water cooling.

Pulp Temperature Rise Induced by Light-Emitting Diode Light-Curing Units Using an Ex Vivo Model.

The aim of this research was to compare the pulp temperature (PT) rise induced by four light-emitting diode light-curing units (LED LCUs) (Bluephase 20i, Demi Ultra, SPEC 3, and Valo) in different curing modes. Immediately after extraction, the pulp chamber of 11 premolars was accessed from the palatal cervical third of the crown for insertion of fiber Bragg grating (FBG) sensors for temperature measurement and kept in a 37.0° water bath. The teeth were then submitted to a random sequence of curing modes with four irradiations at 30 s intervals. Care was taken to ensure complete pulp temperature reset between curing modes. The curing modes were classified as high-energy (above 80 J/cm2) or low-energy (below 40 J/cm2) according to the total energy density delivered. Statistical analysis was performed with repeated ANOVA measures and Pearson’s correlation for the association between energy density and temperature variation. The significance level was set to 0.05. All curing units promoted a statistically significant PT rise (p < 0.01). After four emissions, the PT rise was higher than 5.0 °C for the high-energy curing modes. The low-energy modes induced approximately a 2.5 °C rise. A strong positive correlation was found between energy density and PT increase (R = 0.715; p = 0.01). Exposure of intact premolars to LED LCUs induced significant and cumulative PT rise. Curing modes emitting high energy densities produced higher PT variations. Radiant exposure was positively correlated to PT variation.

Effect of different stripping techniques on pulpal temperature: in vitro study.

ABSTRACTIntroduction: Proximal stripping of enamel is a routine clinical procedure employed in orthodontics to create space or for balancing tooth size discrepancies. This procedure may result in heat transfer to the pulp, predisposing it to histopathological changes and necrosis of the pulp tissue.Objective: To measure the temperature changes in the pulp chamber during different stripping procedures. Methods: 80 proximal surfaces of 40 extracted human premolar teeth were stripped using four techniques: diamond burs in air-rotor handpiece with air-water spray; diamond burs in micromotor handpiece, with and without a coolant spray; and hand-held diamond strips. A J-type thermocouple connected to a digital thermometer was inserted into the pulp chamber for evaluation of temperature during the stripping procedure. Results: An increase in the pulpal temperature was observed for all stripping method. Diamond burs in micromotor handpiece without coolant resulted in the higher increase in temperature (3.5oC), followed by hand-held diamond strips (2.8oC), diamond burs in air-rotor with air-water spray (1.9oC); and the smallest increase was seen with diamond burs in micromotor handpiece with coolant (1.65oC). None of the techniques resulted in temperature increase above the critical level of 5.5oC. Conclusion: Frictional heat produced with different stripping techniques results in increase in the pulpal temperature, therefore, caution is advised during this procedure. A coolant spray can limit the increase in temperature of the pulp.

Evaluation of the Shear Bond Strength and Adhesive Remnant Index in Debonding of Stainless Steel Brackets Assisted with Nd:YAG Laser Irradiation.

Objectives:The purpose was to compare shear bond strength (SBS), pulp temperature, and adhesive remnant index (ARI) in debonding of stainless steel brackets from enamel surface using neodymium-doped yttrium aluminum garnet (Nd:YAG) laser versus the conventional debonding method.Materials and Methods:Forty-eight extracted premolars were bonded to stainless steel brackets. The samples were divided into three experimental groups and one control group. In the first three groups, Nd:YAG laser was used for debonding with the power of 1, 1.5, and 2 W, respectively, for 10 seconds. The SBS and ARI of the samples were assessed. Pulp temperature was recorded before and after irradiation. Two samples from each group were used for determining enamel morphology after debonding using scanning electron microscopy (SEM).Results:The mean SBS in the groups was 33.05, 28.69, 24.37, and 31.53 MPa, respectively, with no statistically significant differences (P=0.205). Significant differences in post-irradiation temperature were noted among the lased groups (P=0.000). Debonding mainly occurred at the adhesive-enamel interface in the 1-W laser and control groups and at the bracket-adhesive interface in the 1.5-W and 2-W laser groups. Enamel structure was amorphous and irregular following laser irradiation.Conclusion:Based on the results of this study, the use of Nd:YAG laser could not significantly affect the SBS. Therefore, this laser would not be suitable for debonding of metal brackets. The use of a 2-W laser could significantly raise the pulpal temperature. Nd:YAG laser renders a more heterogeneous enamel morphology compared to conventional debonding methods.

Risk of pulp damage may increase due to intrachamber temperature during the usage of prophylaxis cup without paste

Aim: The aim was to measure in vitro pulp temperature increase over physiologic temperature during usage of different prophylaxis regimes at two different application pressures.Material and Methods: The aim was to measure in vitro pulp temperature increase over physiologic temperature during usage of different prophylaxis regimes at two different application pressures.Results: The aim was to measure in vitro pulp temperature increase over physiologic temperature during usage of different prophylaxis regimes at two different application pressures. Conclusion: Within the limitations of this in vitro study following conclusion can be drawn: Prophylaxis cups without paste generated the highest intrachamber temperature thus, the risk of pulp damage might be increased during its usage. Naturel-bristled prophy brushes generated the lowest intrachamber temperature. Vigorous application pressure increased the intrachamber temperature.

Leaching of a Tailings from Oxy-sulfur Copper Ore with Sulfuric Acid

In this paper, mineralogy and leaching comprehensive utilization of tailings from an oxy-sulfide copper ore were studied. Tailings grade was 0.526%, of which copper was primary free copper oxide. Malachite was not completely dissolved although it flake aggregate size was much larger than other minerals. When the tailings were ground again to a fineness of -0.074 mm 93.5%, the copper grade in the tailings could only be reduced to 0.489% after one roughing and two scavenging. It was difficult to effectively recover copper with conventional flotation methods. Under the pulp concentration of 33%, the pulp temperature of 45 °C and 55 °C, sulfuric acid dosage of 160 kg/t, leaching time of 0.5 h, immersion liquid contained copper 2.37 g/L, the leaching rate of 91.34% was obtained with acid leaching, which the copper tailings got effectively recycled.

Controlling In Vivo, Human Pulp Temperature Rise Caused by LED Curing Light Exposure.

The objective of this study was to evaluate the in vivo effectiveness of air spray to reduce pulp temperature rise during exposure of intact premolars to light emitted by a high-power LED light-curing unit (LCU). After local Ethics Committee approval (#255945), intact, upper first premolars requiring extraction for orthodontic reasons from five volunteers received infiltrative and intraligamental anesthesia. The teeth (n=9) were isolated using rubber dam, and a minute pulp exposure was attained. The sterile probe from a wireless, NIST-traceable, temperature acquisition system was inserted directly into the coronal pulp chamber. Real-time pulp temperature (PT) (°C) was continuously monitored, while the buccal surface was exposed to a polywave LED LCU (Bluephase 20i, Ivoclar Vivadent) for 30 seconds with simultaneous application of a lingually directed air spray (30s-H/AIR) or without (30s-H), with a seven-minute span between each exposure. Peak PT values were subjected to one-way, repeated-measures analysis of variance, and PT change from baseline (ΔT) during exposure was subjected to paired Student's t-test (α=0.05). Peak PT values of the 30s-H group were significantly higher than those of 30s-H/AIR group and those from baseline temperature (p<0.001), whereas peak PT values in the 30s-H/AIR group were significantly lower than the baseline temperature (p=0.003). The 30s-H/AIR group showed significantly lower ΔT values than did the 30s-H group (p<0.001). Applying air flow simultaneously with LED exposure prevents in vivo pulp temperature rise.