Needle Temperature Research Articles

Influence of temperature, needle gauge and injection rate on the size distribution, concentration and acoustic responses of ultrasound contrast agents at high frequency

This paper investigated the influence of needle gauge (19G and 27G), injection rate (0.85ml·min−1, 3ml·min−1) and temperature (room temperature (RT) and body temperature (BT)) on the mean diameter, concentration, acoustic attenuation, contrast to tissue ratio (CTR) and normalised subharmonic intensity (NSI) of three ultrasound contrast agents (UCAs): Definity, SonoVue and MicroMarker (untargeted). A broadband substitution technique was used to acquire the acoustic properties over the frequency range 17–31MHz with a preclinical ultrasound scanner Vevo770 (Visualsonics, Canada). Significant differences (P<0.001−P<0.05) between typical in vitro setting (19G needle, 3ml·min−1 at RT) and typical in vivo setting (27G needle, 0.85ml·min−1 at BT) were found for SonoVue and MicroMarker. Moreover we found that the mean volume-based diameter and concentration of both SonoVue and Definity reduced significantly when changing from typical in vitro to in vivo experimental set-ups, while those for MicroMarker did not significantly change. From our limited measurements of Definity, we found no significant change in attenuation, CTR and NSI with needle gauge. For SonoVue, all the measured acoustic properties (attenuation, CTR and NSI) reduced significantly when changing from typical in vitro to in vivo experimental conditions, while for MicroMarker, only the NSI reduced, with attenuation and CTR increasing significantly. These differences suggest that changes in physical compression and temperature are likely to alter the shell structure of the UCAs resulting in measureable and significant changes in the physical and high frequency acoustical properties of the contrast agents under typical in vitro and preclinical in vivo experimental conditions.

Prediction of needle heating in an industrial sewing machine

In industrial sewing, needle heating is a key problem that limits the further increase of sewing speed, and hence the productivity. Heat is generated during the sewing process because of friction between the needle and the sewing thread as well as between the needle and the fabric. The high temperature of the needle affects the quality and productivity of the sewing. The problem of needle temperature rise due to friction heat generation is considered in this paper and a simple analytical model is developed to predict needle temperature. The predicted needle temperature is compared with the experimental results by the inserted thermocouple method. Some of the process parameters, used as input variables, were also measured experimentally and experimentally observed values of needle temperature were compared with the theoretical prediction. It was observed that the temperature of the needle increases significantly with the presence of the sewing thread. Both the theory and the experimental results show that the needle temperature increases linearly with the machine speed within the ranges studied.

Robotic Partial Nephrectomy With Intracorporeal Renal Hypothermia Using Ice Slush

To outline our technique for intracorporeal cooling with ice slush during robotic partial nephrectomy (RPN), with real-time parenchymal temperature monitoring. Eleven consecutive patients with enhancing solid renal masses suitable for treatment with RPN between September 2013 and January 2014 were included in the analysis. Institutional review board approval and informed consent were obtained. Preoperative patient characteristics, intraoperative surgical parameters including patient body temperature and ipsilateral kidney temperature with real-time monitoring, and short-term functional outcomes were analyzed. Median age was 55 years (range, 39-75 years) and American Society of Anesthesiologists score was 3 (range, 2-4). Median tumor size was 4 cm (range, 2.3-7.1) and RENAL nephrometry score was 9 (range, 5-11). One patient had a solitary kidney. During cooling, the lowest median renal parenchymal temperature was 17.05°C (range, 11°C-26°C) and cold ischemia time was 27.17 minutes (range, 18-49 minutes). Median time to latest postoperative estimated glomerular filtration rate was 12 days (range, 2-30 days). Median glomerular filtration rate preservation was 81% (range, 47.9%-126%). There was one positive margin. There were no postoperative complications, and no patients experienced a prolonged ileus. The limitations of this study include a small number of patients and short-term follow-up. RPN with renal hypothermia using intracorporeal ice slush is technically feasible. Our simplified method of introducing the ice slush was free of complications and highly reproducible. The use of a needle temperature probe allowed us to monitor in real time cooling of the renal parenchyma.

Software Design of Electro-Thermal Acupuncture Treatment Instrument Based on MCU

Electro-thermal acupuncture treatment instrument heats the needle by heat transfer effect, instead of the traditional Chinese thermal needle for acupuncture. It achieves better healing effect on acupuncture points of the human body through the intelligent control of MCU and temperature control device on the needle temperature, vibration frequency, and thermal efficiency and so on. This paper introduces software design of the electro-thermal acupuncture treatment instrument, which is mainly composed of the main program module, temperature acquisition module, timer module, display module, keyboard module and calculation control module. Temperature and vibration frequency of needle body, thermal efficiency, and time of acupuncture are intelligently regulated by MCU, so that treatment effect using electro-thermal acupuncture is better than using traditional Chinese thermal needle.

Observations and models of emissions of volatile terpenoid compounds from needles of ponderosa pine trees growing in situ: control by light, temperature and stomatal conductance.

Terpenoid emissions from ponderosa pine (Pinus ponderosa subsp. scopulorum) were measured in Colorado, USA over two growing seasons to evaluate the role of incident light, needle temperature, and stomatal conductance in controlling emissions of 2-methyl-3-buten-2-ol (MBO) and several monoterpenes. MBO was the dominant daylight terpenoid emission, comprising on average 87% of the total flux, and diurnal variations were largely determined by light and temperature. During daytime, oxygenated monoterpenes (especially linalool) comprised up to 75% of the total monoterpenoid flux from needles. A significant fraction of monoterpenoid emissions was dependent on light and 13CO2 labeling studies confirmed de novo production. Thus, modeling of monoterpenoid emissions required a hybrid model in which a significant fraction of emissions was dependent on both light and temperature, while the remainder was dependent on temperature alone. Experiments in which stomata were forced to close using abscisic acid demonstrated that MBO and a large fraction of the monoterpene flux, presumably linalool, could be limited at the scale of seconds to minutes by stomatal conductance. Using a previously published model of terpenoid emissions, which explicitly accounts for the physicochemical properties of emitted compounds, we were able to simulate these observed stomatal effects, whether induced experimentally or arising under naturally fluctuation conditions of temperature and light. This study shows unequivocally that, under naturally occurring field conditions, de novo light-dependent monoterpenes comprise a significant fraction of emissions in ponderosa pine. Differences between the monoterpene composition of ambient air and needle emissions imply a significant non-needle emission source enriched in Δ-3-carene.

Impact of stitch length on sewing needle temperature

In this article the sewing needle heat is measured without sewing thread and with sewing thread at different stitch density (stitches per inch or SPI) of lock stitch sewing machine by thermocouples. Two methods are used to measure sewing needle heat, touch thermocouple method and inserted thermo couple method. Needle temperature is measured after periodic 10, 20, 30 and 60 seconds of sewing operation. Whereas the machine running at speed from 1000 r/m to 4700 r/m. It is observed that decreasing stitch length causes an increase in the temperature of the sewing needle. Stitch density shows same influence on needle for sewing with thread and without thread. It is observed from our research that at SPI of 14 the needle temperature with thread rises to 259 °C at 4000 r/min of machine. It is recommended to use minimum stitch density.

Optimization of the link drive mechanism in a sewing machine using imperialist competitive algorithm

Purpose – The purpose of this paper is to present, an optimization problem based on the imperialistic competitive algorithm (ICA) approach for optimizing the needle velocity and variation of needle acceleration in a link drive mechanism of a sewing machine. The optimal geometry of the link drive has been achieved using a non-linear optimization procedure. Design/methodology/approach – As an important study in this case, the authors might refer to a previous work in which they introduced the possibility of replacing the slider-crank mechanism, that is typically used in sewing machines, with a link drive mechanism. The authors regenerate the optimization problem by modifying the objective function and follow a novel optimization method based on the ICA to overcome the drawbacks of that work. In addition, further modification of the objective function with respect to the variation of needle acceleration is applied to assure smooth movement of the needle during sewing process. Findings – The results showed a significant improvement with respect to the optimization of needle velocity and variation of needle acceleration in comparison to that previous work. This clearly justifies the efficiency and reliability of the optimization formulation based on the ICA approach. Originality/value – Needle temperature is considered as an effective parameter on sewing process efficiency and stitch quality. Needle heat generated during sewing process is directly related to needle velocity in penetration zone which in turn depends on the needle driver mechanism of sewing machine. According to literature survey, few researches have focussed to design a driver mechanism of the sewing machine to reduce the generated needle heat. This mechanism has the ability of reducing the penetration velocity of the needle without affecting sewing speed which consequently can reduce the needle heat generated during needle penetration. The work here is novel regarding implementation of optimization algorithm for this mechanism.

Tensile Properties of Sewing Thread and Sewing Needle Temperature at Different Speed of Sewing Machine

Needle heatup is a big issue for apparel industry especially for automobile industry seat covers where a lot of synthetic materials are used which get damaged by needle heat at high speed of sewing machine,in this article thermocamera and thermocouple are used to measure the precise temperature of needle eye and then 100% polyester 35x3 Tex thread is taken for sewing,the lockstitch sewing machine is run at 1000rpm,2000rpm and 3000rpm respectively and the both methods are used to obtain the accurate needle temperature and finally thread tensile properties are measured before the sewing and taking out the thread from the seam precisely to get the tensile properties of thread after 10,30 and 60 seconds of continuous stitching,the article is very helpful in predicting the exact temperature of needle in lock stitch machine and getting the damage to thread by the needle heat at different speeds and different stages of sewing process.

Radiofrequency ablation for recurrent hepatocellular carcinoma in postresectional patients

Percutaneous ablation therapies can be used for recurrent hepatocellular carcinoma (HCC) in postresectional patients not eligible for repeat surgery. To determine prognostic factors affecting the disease-free survival of postresectional patients after percutaneous ultrasound-guided radiofrequency ablation (RFA) for recurrent HCC. From August 2003 to December 2009, patients who had received previous hepatectomy because of HCC and suffered from tumor recurrence were included. Among them, 82 patients who received initial percutaneous ultrasound-guided RFA were included. Various host, treatment, and therapeutic-related factors were analyzed. Eighty-two patients (64 men, mean age 64.27 years) were included. Sex (P=0.495), age (P=0.840), hepatitis marker (P=0.083), and Child-Pugh score (P=0.809) were not related to prognosis. Preresectional tumor number (P=0.502), recurrent tumor location (P=0.795), recurrent tumor number (P=0.533), pathology proved cirrhosis (P=0.889), and OKUDA stage of the primitive disease (P=0.865) were not related to prognosis, either. Survival rates were significantly related to the preresectional tumor size (P=0.008), microscopic portal vein invasion (P=0.001), recurrent tumor size (P<0.001), and preablation α-fetoprotein serum level (P=0.006). Ablation needle (P=0.373), ablation time (P=0.387), and postablation temperature (P=0.444) were not related to prognosis. Multivariate analysis revealed that microscopic portal vein invasion was the only factor that had a significant effect on patient survival. In patients with postresectional HCC treated with percutaneous ultrasound-guided RFA for recurrent disease, those without microscopic portal vein invasion had a significantly higher probability of disease-free survival.

Needle Temperature Effect on Pain Ratings After Injection

Little research regarding appropriate immunization administration technique for adults has been carried out. Pain is a leading cause of self-deferral from immunizations. The purpose of this study was to determine whether administering intramuscular injections using cold needles would decrease patients' perceived pain and have an effect on the immune response elicited by the vaccine. Eighty participants received an injection of influenza vaccine in 1 arm and a saline injection in the other using a cold or room temperature needle in a double-blind fashion assigned at random. Participants rated their pain after each injection using a standard visual pain scale bounded by no pain and most painful injection ever. Vaccine antibody response was measured using hemagglutination inhibition assays. Overall, pain scores after influenza vaccine administration were quite low (34.2+/-2.5 mm). The mean pain score for influenza vaccine was not different using cold or room temperature needles (cold 32.2 mm+/-3.20 vs. room temperature 36.0 mm+/-3.80; t=0.76; P=0.450). The mean pain scores for saline injections did not differ (room temperature 23.7 mm+/-3.19 vs. cold 25.2+/-2.95; t=-0.34; P=0.73). Individuals receiving injections with cold needles had less bruising (0/40 vs. 5/40; P<0.02) at the injection site, but incidences of pain and erythema were similar. The use of cold needles for vaccine administration had no effect on antibody response. Pain after influenza vaccine administration is generally mild. Use of cold needles may not be worth pursuing for injections associated with mild pain. However, it may be worthwhile to explore using cold needles as an analgesic with more painful injections.

低侵襲治療におけるマイクロ波凝固療法, ラジオ波焼灼療法, 超音波駆動メスの腎組織に対する影響

The objective of this study was to optimize least invasive techniques, like microwave tissue coagulation (MCT), radiofrequency ablation (RFA) or ultrasonically-activated scalpel (USS) for the electric and thermal conduction in kidney. Needle electrode of MCT, RFA or USS were inserted into pig's kidney, under general anesthesia. We examined if the interruption of renal artery or cooling of renal parenchyma by irrigation in the renal pelvis had an effect on the tissue temperature distribution and area of tissue degeneration. The tissue parenchyma temperatures were measured at regular intervals of area (each 2.5-5.0 mm) from needle electrode or hook probe and of time (each 10 sec) using by needle temperature sensor, and pathological investigations on the tissue degeneration of the renal parenchyma were done. By MCT, interruption of renal artery had no effect on the distribution of tissue temperature and the area of tissue degeneration. Cooling of renal parenchyma by irrigation in the renal pelvis did not affect the area of tissue degeneration but the tissue temperature was elevated significantly. By RFA, particular interest, interruption of renal artery and cooling of renal parenchyma enhanced to increase both the tissue temperature and the area of tissue degeneration. By USS, interruption of renal artery enhanced to increase both the tissue temperature and the area of tissue degeneration. Cooling of renal parenchyma by irrigation in the renal pelvis had no effect on the distribution of temperature and the area of tissue degeneration. We also examined weather cooling of renal parenchyma by several irrigation solutions which have different electric conductivity (EC) such as normal saline solution (EC: 15,800 microS/cm), tap water (EC: 133 microS/cm) and glucose solution (EC: 8.6 microS/cm) in the renal pelvis using ureteral catheter would effect on the distribution of temperature and the area of tissue degeneration. In MCT and USS, these solutions did not have any effect, but in RFA the degree of tissue temperature elevation by normal saline, tap water and glucose solution were high, intermediate and low, respectively. As RFA and USS tend to be affected by the surrounding environment, electric and thermal conductivity should be applied with caution, while using these techniques.

Trace analysis of chlorobenzenes in water samples using headspace solvent microextraction and gas chromatography/electron capture detection

In the present work, a rapid method for the extraction and determination of chlorobenzenes (CBs) such as monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene in water samples using the headspace solvent microextraction (HSME) and gas chromatography/electron capture detector (ECD) has been described. A microdrop of the dodecane containing monobromobenzene (internal standard) was used as extracting solvent in this investigation. The analytes were extracted by suspending a 2.5 μl extraction drop directly from the tip of a microsyringe fixed above an extraction vial with a septum in a way that the needle passed through the septum and the needle tip appeared above the surface of the solution. After the extraction was finished, the drop was retracted back into the needle and injected directly into a GC column. Optimization of experimental conditions such as nature of the extracting solvent, microdrop and sample temperatures, stirring rate, microdrop and sample volumes, the ionic strength and extraction time were investigated. The optimized conditions were as follows: dodecane as the extracting solvent, the extraction temperature, 45 °C; the sodium chloride concentration, 2 M; the extraction time, 5.0 min; the stirring rate, 500 rpm; the drop volume, 2.5 μl; the sample volume, 7 ml; the microsyringe needle temperature, 0.0 °C. The limit of detection (LOD) ranged from 0.1 μg/l (for 1,3-dichlorobenzene) to 3.0 μg/l (for 1,4-dichlorobenzene) and linear range of 0.5–3.0 μg/l for 1,2-dichlorobenzene, 1,3-dichlorobenzene and from 5.0 to 20.0 μg/l for monochlorobenzene and from 5.0 to 30 μg/l for 1,4-dichlorobenzene. The relative standard deviations (R.S.D.) for most of CBs at the 5 μg/l level were below 10%. The optimized procedure was successfully applied to the extraction and determination of CBs in different water samples.

Rapid extraction and analysis of volatile organic compounds of Iranian feverfew (Tanacetum parthenium) using headspace solvent microextraction (HSME), and gas chromatography/mass spectrometry

AbstractIn the present study, we have utilized headspace solvent microextraction (HSME) as a modern and rapid sample preparation method for the isolation and preconcentration of the volatile organic compounds (VOCs) from the headspace of a plant into a microdrop. The extraction was done by suspending a microliter drop of the solvent from the tip of a microsyringe to the headspace of dried and powdered feverfew flowers (Tanacetum parthenium) in a sealed vial for a preset extraction time. Then, the microdrop was retracted back into the microsyringe and injected directly into a GC injection port. In this study, the identification of the VOCs extracted by HSME was confirmed according to their retention indices and mass spectra (EI, 70 eV) and quantitative analysis was performed by GC‐FID. Parameters such as the nature of the extracting solvent, particle size of the sample, temperatures of the microdrop and sample, volumes of the microdrop and sample and the extraction time were studied and optimized and the method performance was evaluated. The optimized conditions were: sample particle size, 0.65 mm; sample volume, 8 ml (in a 15 ml vial); sample temperature, 50 °C; microsyringe needle temperature, 25 °C (room temperature); microdrop volume, 3 µl and extraction time, 8 min. Finally, under optimum working conditions, the percentage of the VOCs extracted from the headspace and the relative standard deviation of the extraction for each compound based on seven replicated analyses were evaluated. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Diurnal course of photochemical activity of winter-adapted Scots pine at subzero temperatures

The photochemical activity of native Central Siberian Scots pine trees (Pinus sylvestris L) was estimated from the middle of February to the middle of March 2001. We measured chlorophyll (Chl) fluorescence in attached intact needles from trees located approx. 30 km west of the Yenisey river (60°44′N, 89°09′E) near the village of Zotino. In this period, the air temperature varied between −39 °C and +7 °C. At temperatures below −10 °C, P. sylvestris needles did not exhibit any variable Chl fluorescence during the daylight period. During the night, however, the effective quantum yield of photosystem 2 (PS2) photochemistry, Φ2 [Φ2 = (Fm′ − Ft)/Fm′), increased from values near zero to values between 0.05 and 0.20 depending on the needle temperature and sample investigated. The increase started soon after dusk and lasted for 3–6 h depending on the temperature. A faster increase of Φ2 was found for temperatures around −16 °C, and lower rates occurred at lower temperatures. Irrespective of the temperature, Φ2 decreased rapidly to near zero values at dawn, when the photosynthetic photon flux density increased to about 1–5 µmol m−2 s−1, and remained near zero throughout the day. At temperatures higher than −10 °C, the diurnal decrease and the nocturnal increase of Φ2 were less distinct or disappeared completely. Hence the winter-adapted Scots pine maintains some photochemical activity of PS2 even at extremely cold temperatures. The capacity of photochemical reactions below −10 °C is, however, very limited and PS2 photochemistry is saturated by an extremely low irradiance (less than 5 µmol m−2 s−1).

Headspace solvent microextraction: a very rapid method for identification of volatile components of Iranian Pimpinella anisum seed

At the present study, a new and rapid headspace solvent microextraction (HSME), for the extraction and pre-concentration of the volatile components of plant sample into a microdrop was applied. The extraction occurred by suspending a microliter drop of the solvent from the tip of a microsyringe to the headspace of a ripen and powdered dry fruit sample (Iranian Pimpinella anisum seed) in a sealed vial for a preset extraction time, then the microdrop was retracted back into the microsyringe and injected directly into a GC injection port. The chemical composition of the HSME extracts were confirmed according to their retention indexes and mass spectra (EI, 70 eV); and quantitative analysis was performed by GC–FID. Parameters such as the nature of the extracting solvent, particle size of the sample, temperatures of the microdrop and sample, volume of sample and the extraction time were studied and optimized, and the method's performance was evaluated. The optimized conditions were: sample particle size, 1 mm; sample volume, 5 ml (in a 15 ml vial); sample temperature, 60 °C; microsyringe needle temperature, 0 °C; and extraction time, 10 min. Finally, accordingly, the percentage of trans-anethole (the major compound of P. anisum) and the relative standard deviation for extraction and determination of trans-anethole (seven-replicated analysis) were determined to be 90% and 3.9%, respectively.

A needle temperature microsensor for in vivo and real-time measurement of the temperature in acupoints

Abstracts A novel needle temperature microsensor measurement system was established to study the temperature characteristics in acupoints. Before used in vivo, the needle temperature microsensor was tested in vitro and proved stable, accurate and sensitive. Its measurement error was no more than ±0.1 °C by calibration. Its resolution was 0.1 °C and response time was less than 1 s. The measurement ranged from 20 to 40 °C. The in vivo experiments showed that the temperature of the acupoints ascended significantly higher than that of the left and right non-acupoints (parallel to the detected acupoints and 1.0 cm apart from them) after electroacupuncture (EA) at other acupoints, which were located on the same meridian line with the detected acupoints but 6–10 cm away from them. The results indicated that the needle temperature microsensor had a good performance in vivo. Furthermore, it supplied a reliable tool for the study of the mechanism of acupuncture and meridians.

Modeling of Positive-Displacement Fluid Dispensing Processes

Dispensing has been widely used in industry to precisely control the delivery of fluid materials. Among several approaches, positive-displacement dispensing by employing the linear movement of a motor-driven piston is recognized as the most promising because the approach is assumed to be "true" volumetric dispensing. This is true for dispensing a large volume of fluid with continuous piston motion. As the volume of fluid decreases to the micro-liter range, however, this assumption is no longer valid because the fluid properties, in particular the compressibility and flow behavior, can have a significant influence on the volume of fluid dispensed. Taking into account the influence, This work presents the development of a model for the positive-displacement dispensing process. The model is then used to investigate the process performance, with the emphasis on identifying the influence of such factors as the fluid volume in a syringe, the needle temperature, and the fluid properties on the consistency in volume of fluid dispensed.

Trace analysis of methyl tert-butyl ether in water samples using headspace solvent microextraction and gas chromatography–flame ionization detection

In this study, a simple, rapid and efficient method for the extraction and determination of MTBE in water samples by the headspace solvent microextraction (HSME) and gas chromatography at sub (μg/l) level is described. Some significant variables such as type of solvent, extraction time, salt concentration, sample and microdrop volumes, stirring rate, sample and microsyringe needle temperatures were optimized. Using optimum extraction conditions (benzyl alcohol as extracting solvent, 4 M NaCl, sample temperature 35 °C, sample volume 6 ml, stirring rate 1000 rpm, microsyring needle temperature −6 °C, extraction time 7.5 min and micro drop volume of 2 μl) a detection limit of 0.06 μg/l and a good linearity ( R 2 > 0.999) in a calibration range of 0.1–500 μg/l were achieved. This HSME method was applied to the analysis of MTBE in tap, well and spring waters and a groundwater sample contaminated by leaking gasoline from an underground storage tank (LUST) in a gasoline service station.

Headspace solvent microextraction of trihalomethane compounds into a single drop.

Headspace solvent microextraction (HSME) into a single drop is developed for the determination of six trihalomethanes, CH2Cl2, CHCl3, C4H9Cl, CCl4, C2HCl3, and C2Cl4, in aqueous solution. A drop of benzyl alcohol containing bromoform, as an internal standard, is used for extraction. The analytes are extracted by suspending a 3-microL drop directly from the needle of a microsyringe. The needle passes through the septum of a vessel, and the needle tip appears above the surface of the solution. After the prescribed extraction time, the drop is drawn back into the syringe. The syringe is then removed, and its content is injected directly into a gas chromatography column for analysis. The main parameters affecting the HSME process, such as stirring speed, microdrop volume, sample solution temperature, microsyringe needle temperature, sample volume, solution pH, extracting solvent, and ionic strength of the solution, are studied. Also, the linear range and precision of the method are examined.

Gas exchange characteristics of Pinus canariensis needles in a forest stand on Tenerife, Canary Islands

Gas exchange characteristics and chlorophyll fluorescence of the Canarian endemic pine (Pinus canariensis) were measured during the day for a year in a field stand on Tenerife, Canary Islands, Spain. Diurnal tendencies of gas exchange were variable depending on ambient conditions. In general they paralleled photosynthetic photon flux density with only one peak at midday, except on summer days with high air vapour pressure deficit (VPD), when needles exhibited a severe midday depression of CO2 assimilation rate (A), in parallel with a reduction of stomatal conductance (gs). The internal CO2 concentration tendencies during the day suggest that stomatal closure was the main cause of the midday depression of photosynthesis. Chlorophyll fluorescence data corroborate this assertion, with the parameter Fv/Fm reaching high values throughout day and year. P. canariensis living in the sub-tropic exhibited high values of A (maximal A value of 17 µmol m−2 s−1) and high optimal needle temperature for photosynthesis (25°C) which were at the upper limit of the values given for conifers and similar only to data obtained for some pine species adapted to habitats at similar latitudes. gs was reduced to half when VPD attained 40 mbar, allowing this pine to have high A/gs values during high evaporative demand conditions.