Does ear C sink strength contributes to the overcoming of photosynthetic acclimation of wheat plants exposed to elevated CO2?

Wheat plants (Triticum durum Desf., cv. Regallo) were grown in the field to study the effects of contrasting [CO2] conditions (700 versus 370 μmol mol−1) on growth, photosynthetic performance, and C management during the post-anthesis period. The aim was to test whether a restricted capacity of sink organs to utilize photosynthates drives a loss of photosynthetic capacity in elevated CO2. The ambient 13C/12C isotopic composition (δ13C) of air CO2 was changed from-10.2 in ambient [CO2] to-23.6 under elevated [CO2] between the 7th and the 14th days after anthesis in order to study C assimilation and partitioning between leaves and ears. Elevated [CO2] had no significant effect on biomass production and grain filling, and caused an accumulation of C compounds in leaves. This was accompanied by up-regulation of phosphoglycerate mutase and ATP synthase protein content, together with down-regulation of adenosine diphosphate glucose pyrophosphatase protein. Growth in elevated [CO2] negatively affected Rubisco and Rubisco activase protein content and induced photosynthetic down-regulation. CO2 enrichment caused a specific decrease in Rubisco content, together with decreases in the amino acid and total N content of leaves. The C labelling revealed that in flag leaves, part of the C fixed during grain filling was stored as starch and structural C compounds whereas the rest of the labelled C (mainly in the form of soluble sugars) was completely respired 48 h after the end of labelling. Although labelled C was not detected in the δ13C of ear total organic matter and respired CO2, soluble sugar δ13C revealed that a small amount of labelled C reached the ear. The 12CO2 labelling suggests that during the beginning of post-anthesis the ear did not contribute towards overcoming flag leaf carbohydrate accumulation, and this had a consequent effect on protein expression and photosynthetic acclimation.

Desarrollo de nuevos materiales sólidos para la captura de CO2 a alta temperatura

El efecto invernadero provocado por la emisión masiva de CO2 derivado de la combustión de derivados fósiles, entre otros, está provocando serios problemas ambientales que afectan a ecosistemas de todo el planeta. Para reducir las emisiones se emplea la ciencia para diseñar nuevos métodos para capturar CO2 proveniente de la industria, transporte, energía, etc., y así causar el mínimo impacto ambiental posible hasta que dispongamos de la tecnología suficiente para abastecer la demanda energética por fuentes renovables. Entre las distintas tecnologías existentes, el trabajo pretende desarrollar un material sintético basado en calcio para captura Post-Combustión de CO2 en condiciones de presión atmosférica y alta temperatura (750 ºC) para la principal aplicación en centrales termoeléctricas. El material ha sido sintetizado por duplicado aplicando una caracterización de área superficial BET, microestructura con MEB, detección de fases con XRD y finalmente un estudio de la captura de CO2 con microbalanza de suspensión magnética. También es objetivo del trabajo estudiar el comportamiento de captura del material cuando existe la presencia de agua y/o SO2 éste normalmente presente en los gases de salida procedentes de la combustión de combustibles fósiles, tal como carbón, petróleo o gas natural. De nuevo las técnicas mencionadas han sido utilizadas para el estudio del comportamiento de captura. El material, tiene una captura de CO2 superior a otros materiales utilizados con el mismo fin. Se comporta mejor en presencia de agua y se anula la capacidad de captura por la formación de CaSO4, si en el flujo de gases está presente SO2 en una concentración mínima del 0,95%. Finalmente se realiza una breve mención sobre el posible impacto ambiental de la implantación del material así como un pequeño análisis de costes asociados a la utilización del mismo en comparación con otro material utilizado actualmente.

CO2 wedged hepatic venography in the evaluation of portal hypertension.

BACKGROUND/AIMS/METHODS During hepatic vein catheterisation, in addition to measurement of hepatic venous pressure gradient (HVPG), iodine wedged retrograde portography can be easily obtained. However, it rarely allows correct visualisation of the portal vein. Recently, CO2 has been suggested to allow better angiographic demonstration of the portal vein than iodine. In this study we investigated the efficacy of CO2 compared with iodinated contrast medium for portal vein imaging and its role in the evaluation of portal hypertension in a series of 100 patients undergoing hepatic vein catheterisation, 71 of whom had liver cirrhosis. RESULTS In the overall series, CO2 venography was markedly superior to iodine, allowing correct visualisation of the different segments of the portal venous system. In addition, CO2, but not iodine, visualised portal-systemic collaterals in 34 patients. In cirrhosis, non-visualisation of the portal vein on CO2 venography occurred in 11 cases; four had portal vein thrombosis and five had communications between different hepatic veins. Among non-cirrhotics, lack of portal vein visualisation had a 90% sensitivity, 88% specificity, 94% negative predictive value, and 83% positive predictive value in the diagnosis of pre-sinusoidal portal hypertension. CONCLUSIONS Visualisation of the venous portal system by CO2 venography is markedly superior to iodine. The use of CO2 wedged portography is a useful and safe complementary procedure during hepatic vein catheterisation which may help to detect portal thrombosis. Also, lack of demonstration of the portal vein in non-cirrhotic patients strongly suggests the presence of pre-sinusoidal portal hypertension.

Aplicaciones del laser de CO2 en odontologia

La incorporación de las nuevas tecnologías en las ciencias de la salud es, hoy en día, una realidad, ante la cual los profesionales sanitarios deben estar preparados. La tecnología láser ofrece numerosas ventajas en casi la totalidad de las especialidades odontológicas. De la amplia gama de láseres disponibles, el láser de CO2 destaca por sus aplicaciones en el ámbito de la cirugía bucal, especialmente en la cirugía de los tejidos blandos, aunque su uso también ha sido estudiado en otras disciplinas como la odontología conservadora y la endodoncia. Su uso no está exento de riesgos, y el odontólogo especializado en cirugía bucal debe poseer los conocimientos y las habilidades pertinentes para su utilización. Las características del láser de CO2 permiten una cirugía rápida y cómoda para el profesional y unas molestias postoperatorias mínimas para el paciente.

Comparative study of upper lip frenectomy with the CO2 laser versus the Er, Cr: YSGG laser

Objectives: To compare upper lip frenulum reinsertion, bleeding, surgical time and surgical wound healing in frenectomies performed with the CO2 laser versus the Er, Cr:YSGG laser. Study design: A prospective study was carried out on 50 randomized pediatric patients who underwent rhomboidal resection of the upper lip frenulum with either the CO2 laser or the Er,Cr:YSGG laser. Twenty-five patients were assigned to each laser system. All patients were examined at 7, 14, 21 days and 4 months after the operation in order to assess the surgical wound healing. Results: Insertion of the frenulum, which was preoperatively located between the upper central incisors, migrated to the mucogingival junction as a result of using both laser systems in all patients. Only two patients required a single dose of 650 mg of paracetamol, one of either study group. CO2 laser registered improved intraoperative bleeding control results and shorter surgical times. On the other hand, the Er,Cr:YSGG laser achieved faster healing. Conclusions: Upper lip laser frenectomy is a simple technique that results in minimum or no postoperative swelling or pain, and which involves upper lip frenulum reinsertion at the mucogingival junction. The CO2 laser offers a bloodless field and shorter surgical times compared with the Er,Cr:YSGG laser. On the other hand, the Er,Cr:YSGG laser achieved faster wound healing.

Short communication. Potential to mitigate anthropogenic CO2 emissions by tillage reduction in dryland soils of Spain

Spain is one of the countries with the highest greenhouse gas (GHG) emissions within the EU-27. Consequently, mitigation strategies need to be reported and quantified to accomplish the goals and requirements of the Kyoto Protocol. In this study, a first estimation of the carbon (C) mitigation potential of tillage reduction in Mediterranean rainfed Spain is presented. Results from eight studies carried out in Spain under rainfed agriculture to investigate the effects of no-tillage (NT) and reduced tillage (RT) compared with conventional tillage (CT) on soil organic carbon (SOC) were used. For current land surface under conservation tillage, NT and RT are sequestering 0.14 and 0.08 Tg C yr-1, respectively. Those rates represent 1.1% and 0.6% of the total CO2 emissions generated from agricultural activities in Spain during 2006. Alternatively, in a hypothetical scenario where all the arable dryland was under either NT or RT management, SOC sequestration would be 2.18 and 0.72 Tg C yr-1 representing 17.4% and 5.8% of the total 2006 CO2 equivalent emissions generated from the agricultural sector in Spain. This is a significant estimate that would help to achieve GHG emissions targets for the current commitment period of the Kyoto Protocol.

On the relationship between C and N fixation in nodulated alfalfa (Medicago sativa)

Legumes such as alfalfa (Medicago sativa L.) are vital N2-fixing crops accounting for a global N2 fixation of ~35 MtNyear-1. Although enzymatic and molecular mechanisms of nodule N2 fixation are now well documented, some uncertainty remains as to whether N2 fixation is strictly coupled with photosynthetic carbon fixation. That is, the metabolic origin and redistribution of carbon skeletons used to incorporate nitrogen are still relatively undefined. Here, we conducted isotopic labelling with both 15N2 and 13C-depleted CO2 on alfalfa plants grown under controlled conditions and took advantage of isotope ratio mass spectrometry to investigate the relationship between carbon and nitrogen turn-over in respired CO2, total organic matter and amino acids. Our results indicate that CO2 evolved by respiration had an isotopic composition similar to that in organic matter regardless of the organ considered, suggesting that the turn-over of respiratory pools strictly followed photosynthetic input. However, carbon turn-over was nearly three times greater than N turn-over in total organic matter, suggesting that new organic material synthesised was less N-rich than pre-existing organic material (due to progressive nitrogen elemental dilution) or that N remobilisation occurred to sustain growth. This pattern was not consistent with the total commitment into free amino acids where the input of new C and N appeared to be stoichiometric. The labelling pattern in Asn was complex, with contrasted C and N commitments in different organs, suggesting that neosynthesis and redistribution of new Asn molecules required metabolic remobilisation. We conclude that the production of new organic material during alfalfa growth depends on both C and N remobilisation in different organs. At the plant level, this remobilisation is complicated by allocation and metabolism in the different organs. Additional keywords: carbon exchange, carbon isotopes, nitrogen fixation, nitrogen 15 isotope

Histologic evaluation of thermal damage produced on soft tissues by CO2, Er,Cr:YSGG and diode lasers

Objective: The aim of this in vitro experimental study was to perform histological evaluation of the thermal effect produced on soft tissue irradiated with CO2, Er,Cr:YSGG or diode lasers. Study design: Porcine oral mucosa samples were irradiated with Er,Cr:YSGG laser at 1 W with and without water / air spray, at 2 W with and without water / air spray, and at 4 W with water / air spray, with CO2 laser at 1 W, 2 W, 10 W, 20 W continuous mode and 20 W pulsed mode and diode laser at 2W, 5W, and 10W pulsed mode. The thermal effect was evaluated measuring the width of damaged tissue adjacent to the incision, stained positively for hyalinized tissue with Hematoxylin-Eosin and Masson Trichrome stains. Besides, histological changes in the irradiated tissue were described using subjective grading scales. Results: The evaluated lasers developed a wide range of thermal damage with significant differences between groups. The samples with lowest thermal effect were those irradiated with Er,Cr:YSGG laser using water / air spray, followed by CO2 and diode lasers. Conclusions: Emission parameters of each laser system may influence the thermal damage inflicted on the soft tissue, however, the wave length of each laser determines the absorption rate characteristics of every tissue and the thermal effect

Thermal increment due to ErCr: YSGG and CO2 laser irradiation of different implant surfaces. A pilot study

Objective: An evaluation and comparison is made of the thermal increment at different implant surfaces during irradiation with CO2 and ErCr:YSGG lasers. Study design: Five threaded and impacted implants with four types of surfaces were inserted in an adult pig rib: two implants with a hydroxyapatite surface (HA)(impacted and threaded, respectively), a machined titanium surface implant (TI mach), a titanium plasma spray surface implant (TPS), and a sandblasted, acid-etched surface implant (SBAE). A 0.5-mm diameter bone defect was made in the implant apical zone, and a type-K thermocouple (Termopar)® was placed in contact with the implant. The implants were irradiated in the coronal zone of each implant with a CO2 (4 W continuous mode) and an ErCr:YSGG laser (1.5 W, pulsed mode) first without and then with refrigeration. The temperature variations at the implant apical surface were recorded. Results: An apical temperature increase was recorded in all cases during CO2 and ErCr:YSGG laser irradiation without refrigeration. However, when the ErCr:YSGG was used with a water spray, a decrease in temperature was observed in all implants. The acid-etched and sandblasted surfaces were those most affected by the thermal changes. Conclusions: The ErCr:YSGG laser with a water spray applied to the sealing cap or coronal zone of the implants does not generate thermal increments in the apical surface capable of adversely affecting osseointegration and the integrity of the peri-implant bone tissue

The effects of depleted, current and elevated growth [CO2] in wheat are modulated by water availability

Drought is the main constraint on wheat yield in Mediterranean conditions. The photosynthesis, chlorophyll fluorescence and plant growth parameters of durum wheat (Triticum turgidum, L. var. durum) were compared at three [CO2] (i.e., depleted 260 ppm, current 400ppm and elevated 700 ppm) in plants subjected to twowater regimes (i.e.,well-wateredWW, and mildwater stress by drought orwater deficit WS), during pre-anthesis, post-anthesis and the end of grain filling. We showed that [CO2] effects on plants are modulated by water availability. Plants at depleted [CO2] showed photosynthetic acclimation (i.e., up-regulation) and reduced plant biomass and Harvest Index, but depleted [CO2] combined with WS has a more negative impact on plants with decreases in C assimilation and biomass. Plants at elevated [CO2] had decreased plant growth and photosynthesis in response to a down-regulation mechanism resulting from a decrease in Rubisco and N content, but plants exposed to a combination of elevated [CO2] and WS were the most negatively affected (e.g., on plant biomass).

Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO2 and water fluxes through combined in situ measurements and ecosystem modelling

Water stress is a defining characteristic of Mediterranean ecosystems, and is likely to become more severe in the coming decades. Simulation models are key tools for making predictions, but our current understanding of how soil moisture controls ecosystem functioning is not sufficient to adequately constrain parameterisations. Canopy-scale flux data from four forest ecosystems with Mediterranean-type climates were used in order to analyse the physiological controls on carbon and water flues through the year. Significant non-stomatal limitations on photosynthesis were detected, along with lesser changes in the conductance-assimilation relationship. New model parameterisations were derived and implemented in two contrasting modelling approaches. The effectiveness of two models, one a dynamic global vegetation model ('ORCHIDEE'), and the other a forest growth model particularly developed for Mediterranean simulations ('GOTILWA+'), was assessed and modelled canopy responses to seasonal changes in soil moisture were analysed in comparison with in situ flux measurements. In contrast to commonly held assumptions, we find that changing the ratio of conductance to assimilation under natural, seasonally-developing, soil moisture stress is not sufficient to reproduce forest canopy CO2 and water fluxes. However, accurate predictions of both CO2 and water fluxes under all soil moisture levels encountered in the field are obtained if photosynthetic capacity is assumed to vary with soil moisture. This new parameterisation has important consequences for simulated responses of carbon and water fluxes to seasonal soil moisture stress, and should greatly improve our ability to anticipate future impacts of climate changes on the functioning of ecosystems in Mediterranean-type climates.