Zeitschriftenartikel: „Senzor CO2“

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Handlogten, Mary E., Naoki Shiraishi, Hisataka Awata, Chunfa Huang und R. Tyler Miller. „Extracellular Ca2+-sensing receptor is a promiscuous divalent cation sensor that responds to lead“. American Journal of Physiology-Renal Physiology 279, Nr. 6 (01.12.2000): F1083—F1091. http://dx.doi.org/10.1152/ajprenal.2000.279.6.f1083.

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The extracellular Ca2+-sensing receptor (CaR) responds to polycations, including Ca2+ and neomycin. This receptor is a physiological regulator of systemic Ca2+ metabolism and may also mediate the toxic effects of hypercalcemia. A number of divalent cations, including Pb2+, Co2+, Cd2+, and Fe2+, are toxic to the kidney, brain, and other tissues where the CaR is expressed. To determine which divalent cations can activate the CaR, we expressed the human CaR in HEK-293 cells and measured activation of phospholipase A2(PLA2) and the mitogen-activated protein kinase p42ERK in response to potential agonists for the receptor. HEK-293 cells expressing the nonfunctional mutant CaR R796W served as controls. Extracellular Ca2+, Ba2+, Cd2+, Co2+, Fe2+, Gd3+, Ni2+, Pb2+, and neomycin activated the CaR, but Hg2+and Fe3+ did not. We analyzed the kinetics of activation of p42ERK and PLA2 by the CaR in response to Ca2+, Co2+, and Pb2+. The EC50 values ranged from ∼0.1 mM for Pb2+ to ∼4.0 mM for Ca2+. The Hill coefficients were >3, indicating multiple cooperative ligand binding sites or subunits. Submaximal concentrations of Ca2+ and Pb2+ were additive for activation of the CaR. The EC50 for Ca2+ or Pb2+ was reduced four- to fivefold by the presence of the other ion. These divalent cations also activated PLA2 via the CaR in Madin-Darby canine kidney cells that stably express the CaR. We conclude that many divalent cations activate the CaR and that their effects are additive. The facts that the CaR is a promiscuous polycation sensor and that the effects of these ions are additive to activate it suggest that the CaR may contribute to the toxicity of some heavy metals such as Pb2+, Cd2+, Co2+, and Fe2+ for the kidney and other tissues where it is expressed.

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Chen, Guo Feng, Hsiao Pin Tsai, Ping Shan Lai und Ming Yuan Liao. „Functionalized Mn2+ Doped Zinc Sulfide Quantum Dots as a Metal Ion Sensor for Industrial Wastes“. Applied Mechanics and Materials 284-287 (Januar 2013): 138–42. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.138.

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L-cysteine capped Mn2+-doped ZnS quantum dots are prepared as a fluorescence probe for the detection of heavy metal contaminants, such as As2O42-, Cd2+, CrO42-, Ni2+, Zn2+, Ca2+, Fe2+, Cu2+, Pb2+, Co2+ and Mn2+ ions. The results show L-cysteine capped Mn2+-doped ZnS quantum dots exhibit good sensitivity and selectivity for the detection of copper ions. The relationship between the detection limit, linear range and the concentration of quantum dots are examined. The optimum fluorescence sensor is obtained at the L-cysteine-ZnS QDs concentration of 2 mg/mL and pH 7.0 in phosphate buffer. The limit of detection for this sensor system is 0.2 ppm with the linear range between 0.5 and 20 ppm. The effect of foreign ions from Mn2+, Fe2+, Co2+ and Ni2+ for the detection of Cu2+ solution is also evaluated. The results show there is no significant difference on the measurement of quenching effect.

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Bouyer, Patrice, Yuehan Zhou und Walter F. Boron. „An increase in intracellular calcium concentration that is induced by basolateral CO2 in rabbit renal proximal tubule“. American Journal of Physiology-Renal Physiology 285, Nr. 4 (Oktober 2003): F674—F687. http://dx.doi.org/10.1152/ajprenal.00107.2003.

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Working with isolated perfused S2 proximal tubules, we asked whether the basolateral CO2 sensor acts, in part, by raising intracellular Ca2+ concentration ([Ca2+]i), monitored with the dye fura 2 (or fura-PE3). In paired experiments, adding 5% CO2/22 mM [Formula: see text] (constant pH 7.40) to the bath (basolateral) solution caused [Ca2+]i to increase from 57 ± 3 to 97 ± 9nM( n = 8, P < 0.002), whereas the same maneuver in the lumen had no effect. Intracellular pH (pHi), measured with the dye BCECF, fell by 0.54 ± 0.08 ( n = 14) when we added [Formula: see text] to the lumen. In 14 tubules in which we added [Formula: see text] to the bath, pHi fell by 0.55 ± 0.11 in 9 with a high initial pHi, but rose by 0.28 ± 0.07 in the other 5 with a low initial pHi. Thus it cannot be a pHi change that triggers the [Ca2+]i increase. Introducing to the bath an out-of-equilibrium (OOE) solution containing 20% CO2/no [Formula: see text] caused [Ca2+]i to rise by 62 ± 17 nM ( n = 10), whereas an OOE solution containing 0% CO2/22 mM [Formula: see text] caused only a trivial increase. Removing Ca2+ from the lumen and bath, or adding 10 μM nifedipine (L- and T-type Ca2+-channel blocker) or 2 μM thapsigargin [sarco-(endo) plasmic reticulum Ca2+-ATPase inhibitor] or 4 μM rotenone (mitochondrial inhibitor) to the lumen and bath, failed to reduce the CO2-induced increase in [Ca2+]i. Adding 10 mM caffeine (ryanodine-receptor agonist) had no effect on [Ca2+]i. Thus basolateral CO2, presumably via a basolateral sensor, triggers the release of Ca2+ from a nonconventional intracellular pool.

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Zhang, You-Ming, Xiao-Peng Chen, Guo-Yan Liang, Kai-Peng Zhong, Hong Yao, Tai-Bao Wei und Qi Lin. „A water-soluble fluorescent chemosensor based on Asp functionalized naphthalimide for successive detection Fe3+ and H2PO4−“. Canadian Journal of Chemistry 96, Nr. 4 (April 2018): 363–70. http://dx.doi.org/10.1139/cjc-2017-0451.

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The selective recognition of target ions in water is very important and the development of novel water-soluble chemosensor is still an intriguing challenge. Herein, a novel water-soluble fluorescent sensor based on aspartic acid (Asp) functionalized 1,8-naphthalimide derivative (Asp-NI) has been designed and synthesized. The sensor Asp-NI could dissolve in water and successively detect Fe3+ and H2PO4− in water solution with high selectivity and sensitivity. The detection limits are 4.97 × 10−7 mol/L for Fe3+ and 5.27 × 10−6 mol/L for H2PO4−. Other coexistent competitive metal ions (Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+) showed no interference in the Fe3+ detection process. The sensor Asp-NI could act as a Fe3+ and H2PO4− controlled “On–Off–On” fluorescent switch. More interestingly, the Fe3+ induced fluorescence quenching process could be totally reversed by the addition of H2PO4−, this “On–Off–On” switching process could be repeated several times with little fluorescence loss. Notably, the actual usage of sensor Asp-NI was further demonstrated by test kits.

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Zhang Qianqian, 张倩倩, 吴涛 Wu Tao, 孙城林 Sun Chenglin, 叶谌雯 Ye Chenwen, 王梦宇 Wang Mengyu, 范乐康 Fan Lekang, 刘洋 Liu Yang und 何兴道 He Xingdao. „基于中空波导光纤的CO2气体传感器稳定性的研究“. Acta Optica Sinica 41, Nr. 15 (2021): 1528001. http://dx.doi.org/10.3788/aos202141.1528001.

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Floresta, Giuseppe, Nunzio Cardullo, Carmela Spatafora, Antonio Rescifina und Corrado Tringali. „A Rare Natural Benzo[k,l]xanthene as a Turn-Off Fluorescent Sensor for Cu2+ Ion“. International Journal of Molecular Sciences 21, Nr. 18 (21.09.2020): 6933. http://dx.doi.org/10.3390/ijms21186933.

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Rapid and efficient analyses of copper ions are crucial to providing key information for Cu2+ in living cells because of their biological importance. In this study, we reported one new turn-off fluorescent sensor for Cu2+ with a benzo[k,l]xanthene core, which served as an efficient cation sensor for copper ion over a wide range of other cations (Na+, K+, Ag+, Hg2+, Cd2+, Co2+, Ni2+, Zn2+, Mg2+, and Fe3+) owing to the catechol group in the aromatic core. The sensor showed selectivity for Cu2+ over other ions; the logKβ for Cu2+ binding to compound 1 had a value of 13.265. In the presence of Cu2+, sensor 1 provided significant fluorescence decrement; Co2+, and Ni2+ caused a fluorescence decrement when employed at a higher concentration than Cu2+, while Na+, K+, Hg2+, Cd2+, Zn2+, and Mg2+ metal ions produced only minor changes in fluorescence intensity. Fluorescence experiments demonstrate that compound 1 may have an application as a fluorescent probe for detecting Cu2+ with a limit of detection of 0.574 µM.

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De Acha, Nerea, César Elosúa und Francisco J. Arregui. „Development of an Aptamer Based Luminescent Optical Fiber Sensor for the Continuous Monitoring of Hg2+ in Aqueous Media“. Sensors 20, Nr. 8 (22.04.2020): 2372. http://dx.doi.org/10.3390/s20082372.

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A fluorescent optical fiber sensor for the detection of mercury (Hg2+) ions in aqueous solutions is presented in this work. The sensor was based on a fluorophore-labeled thymine (T)-rich oligodeoxyribonucleotide (ON) sequence that was directly immobilized onto the tip of a tapered optical fiber. In the presence of mercury ions, the formation of T–Hg2+-T mismatches quenches the fluorescence emission by the labeled fluorophore, which enables the measurement of Hg2+ ions in aqueous solutions. Thus, in contrast to commonly designed sensors, neither a fluorescence quencher nor a complementary ON sequence is required. The sensor presented a response time of 24.8 seconds toward 5 × 10−12 M Hg2+. It also showed both good reversibility (higher than the 95.8%) and selectivity: the I0/I variation was 10 times higher for Hg2+ ions than for Mn2+ ions. Other contaminants examined (Co2+, Ag+, Cd2+, Ni2+, Ca2+, Pb2+, Mn2+, Zn2+, Fe3+, and Cu2+) presented an even lower interference. The limit of detection of the sensor was 4.73 × 10−13 M Hg2+ in buffer solution and 9.03 × 10−13 M Hg2+ in ultrapure water, and was also able to detect 5 × 10−12 M Hg2+ in tap water.

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FAHRENFORT, I., T. SJOERDSMA, H. RIPPS und M. KAMERMANS. „Cobalt ions inhibit negative feedback in the outer retina by blocking hemichannels on horizontal cells“. Visual Neuroscience 21, Nr. 4 (Juli 2004): 501–11. http://dx.doi.org/10.1017/s095252380421402x.

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In goldfish, negative feedback from horizontal cells to cones shifts the activation function of the Ca2+ current of the cones to more negative potentials. This shift increases the amount of Ca2+ flowing into the cones, resulting in an increase in glutamate release. The increased glutamate release forms the basis of the feedback-mediated responses in second-order neurons, such as the surround-induced responses of bipolar cells and the spectral coding of horizontal cells. Low concentrations of Co2+ block these feedback-mediated responses in turtle retina. The mechanism by which this is accomplished is unknown. We studied the effects of Co2+ on the cone/horizontal network of goldfish retina and found that Co2+ greatly reduced the feedback-mediated responses in both cones and horizontal cells in a GABA-independent way. The reduction of the feedback-mediated responses is accompanied by a small shift of the Ca2+ current of the cones to positive potentials. We have previously shown that hemichannels on the tips of the horizontal cell dendrites are involved in the modulation of the Ca2+ current in cones. Both the absence of this Co2+-induced shift of the Ca2+ current in the absence of a hemichannel conductance and the sensitivity of Cx26 hemichannels to low concentrations of Co2+ are consistent with a role for hemichannels in negative feedback from horizontal cells to cones.

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Boudaden, Jamila, Armin Klumpp, Hanns-Erik Endres und Ignaz Eisele. „Capacitive CO2 Sensor“. Proceedings 1, Nr. 4 (11.08.2017): 472. http://dx.doi.org/10.3390/proceedings1040472.

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Matsubara, Shogo, Shinichiro Kaneko, Shinji Morimoto, Shoichi Shimizu, Tatsumi Ishihara und Yusaku Takita. „A practical capacitive type CO2 sensor using CeO2/BaCO3/CuO ceramics“. Sensors and Actuators B: Chemical 65, Nr. 1-3 (Juni 2000): 128–32. http://dx.doi.org/10.1016/s0925-4005(99)00407-4.

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Harsanyi, Krisztina, und Stuart c. Mangel. „Modulation of cone to horizontal cell transmission by Calcium and pH in the fish retina“. Visual Neuroscience 10, Nr. 1 (Januar 1993): 81–91. http://dx.doi.org/10.1017/s0952523800003242.

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AbstractThe effects of small changes in the calcium and sodium concentrations and in the pH of superfusion medium on the membrane potential and light-evoked responses of cone horizontal cells in the goldfish retina were examined. Conventional intracellular recording, a bicarbonate-based superfusion medium, and a specially designed superfusion apparatus that reduced pressure wave disturbances were used. An increase in the extracellular calcium concentration, [Ca2+]∘ from control levels (0.1 mM) to 1.0 mM hyperpolarized cone horizontal cells and reduced the magnitude of their light responses at all stimulus intensities. Addition of 20 mM NaCl to the 1.0 mM Ca2+ Ringer’s solution reversed the hyperpolarizing effect of the 1.0 mM Ca2+ but addition of 20 mM choline, a monovalent cation that does not pass through cyclic GMP-activated channels, did not. Reduction of the superfusate pH from 7.6 to 7.2 by switching from a Ringer’s solution gassed with 3% CO2 to one gassed with 10% CO2 hyperpolarized horizontal cells and reduced the magnitude of their light responses at all stimulus intensities for both 0.1 and 1.0 mM Ca,2+ Ringer’s solutions. An increase in pH to 8.2 by gassing the superfusate with 1% CO2 slightly depolarized the cells in 0.1 mM Ca2+ Ringer’s solution but slightly hyperpolarized the cells in the 1.0 mM Ca2+ Ringer’s solution. Following pharmacological isolation of the horizontal cells from synaptic input with high doses of glutamate (4–5 mM) and/or Co2+ (4 mM) treatment, no effect on horizontal cell membrane potential due to changes in pH or [Ca2+]∘ was observed. These findings are discussed with respect to the cellular mechanisms and sites of action in the outer retina that are affected by changes in pH∘ and [Ca2+]∘.

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Hayashi, Jon H., und Ann E. Stuart. „Currents in the presynaptic terminal arbors of barnacle photoreceptors“. Visual Neuroscience 10, Nr. 2 (März 1993): 261–70. http://dx.doi.org/10.1017/s0952523800003667.

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AbstractWe have described the currents flowing across the presynaptic membranes of the four median photoreceptors of the giant barnacle, Balanus nubilus, using a quasi-voltage clamp arrangement. Membrane potential, measured in the terminal region of one photoreceptor, was controlled in all four terminals by feedback current supplied through the nerve containing the photoreceptors’ axons. The [Ca2+] ∘ in the saline was reduced to decrease the Ca2+ current, enabling better voltage control, and tetraethylammonium ion (TEA, 20 mM) was added to block a fast voltage-dependent K+ conductance.Depolarizing voltage steps from the resting potential in the dark (−60 mV) evoked slow, inward Ca2+-dependent currents which could be blocked by Co2+, Mg2+, or Cd2+. The Ca2+ currents were followed by large outward currents that persisted for many seconds after the offset of moderate or large pulses. These tail currents increased in magnitude and duration with pulse duration and reversed at about −80 mV, consistent with previous evidence for a Ca2+-activated K+ conductance in this membrane. When the Ca2+-activated outward current was reduced to zero by increasing the [K+]∘ so as to set EK at −20 mV, and then stepping the voltage to this value, the step evoked a steady inward Ca2+ current. Thus, the Ca2+ current did not show voltage- or Ca2+-dependent inactivation. When Ba2+ was substituted for Ca2+, 500-ms depolarizing steps evoked steady inward currents but no outward currents. In any given experiment, the activation voltage of the Ca2+ or Ba2+ current did not depend on holding potential.At the barnacle photoreceptor’s synapse, the postsynaptic cell adapts to maintained presynaptic voltage by a mechanism that is not understood. We conclude that neither Ca2+ current inactivation nor a shift in activation voltage with holding potential can account for this adaptation.

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Widodo, Slamet, M. Miftakul Amin und Adi Sutrisman. „The Design of The Monitoring Tools Of Clean Air Condition And Dangerous Gas CO, CO2 CH4 In Chemical Laboratory By Using Fuzzy Logic Based On Microcontroller“. E3S Web of Conferences 31 (2018): 10008. http://dx.doi.org/10.1051/e3sconf/20183110008.

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There are many phenomena that human are exposed to toxins from certain types such as of CO2, CO2 and CH4 gases. The device used to detect large amounts of CO, CO2, and CH4 gas in air in enclosed spaces using MQ 135 gas sensors of different types based on the three sensitivity of the Gas. The results of testing the use of sensors MQ 135 on the gas content of CO, CO2 and CH4 received by the sensor is still in the form of ppm based on the maximum ppm detection range of each sensor. Active sensor detects CO 120 ppm gas, CO2 1600 ppm and CH4 1ppm "standby 1" air condition with intermediate rotary fan. Active sensor detects CO 30 ppm gas, CO2 490 ppm and CH4 7 ppm "Standby 2" with low rotating fan output. Fuzzy rulebase logic for motor speed when gas detection sensor CO, CO2, and CH4 output controls the motion speed of the fan blower. Active sensors detect CO 15 ppm, CO2 320 ppm and CH4 45 ppm "Danger" air condition with high fan spin fan. At the gas level of CO 15 ppm, CO2 390 ppm and CH4 3 ppm detect "normal" AC sensor with fan output stop spinning.

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Yasmin Sofea Rosland, Nur, Khadijah Ismail, Siti Nooraya Mohd Tawil und Siti Hasnawati Jamal. „PEDOT:PSS/GO NANOCOMPOSITE FOR INDOOR CO2 SENSOR“. International Journal of Advanced Research 9, Nr. 08 (31.08.2021): 473–81. http://dx.doi.org/10.21474/ijar01/13292.

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Carbon dioxide (CO2) which is a colourless and odourless gas, requires an efficient detection, as excessive amount in the environment would possibly leads to global warming. This work discusses on an environmentally friendly and non-toxic CO2 sensor for indoor air monitoring. The fabricated sensor is developed by using poly(3,4ethylenedioxythiophene):poly(4styrenesulfonate)/ graphene oxide (PEDOT:PSS/GO) nanocomposite. Nanocomposite characterisations are performed by using field-emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) to confirm excellent properties of PEDOT:PSS and GO as suitable materials for CO2 sensor development. Fabrication of one layer PEDOT:PSS/GO nanocomposite on environmentally friendly kaolin-coated paper substrate via dip coating method shows good electrical conductivity of 0.25 S. At room temperature, at fixed CO2 flow rate of 0.05 l/min, the fabricated sensor response time is 32 s, with sensor response and sensitivity of 0.8 and 16/l/min respectively. With fast chemiresistive response towards CO2 molecules, the fabricated sensor provides promising results for indoor CO2 monitoring.

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Wang, Hai Rong, Jun Qiang Ren, Guo Liang Sun und Di Cen. „Micro CO₂ Sensor Based on Li₂CO₃, Pt | Li₃PO₄ | Pt, Li₂TiO₃-TiO₂ Structure“. Applied Mechanics and Materials 44-47 (Dezember 2010): 2747–51. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.2747.

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This paper presents a micro solid electrolyte CO2 gas sensor in which Li2CO3, Li2TiO3-TiO2 serves as sensing and reference electrodes respectively, and the Li3PO4 film acts as the electrolyte. The sensor was constructed in the sequent layers of O2, CO2, Li2CO3, Pt | Li3PO4 | Pt, Li2TiO3-TiO2, O2, CO2 on the Al2O3 substrate by MEMS process. Experimental results indicate that the micro solid-electrolyte CO2 gas sensor has a relatively rapid speed of response. By discussions, we may find that the improved performance will be realized by optimizing the primary parameters of the sensor.

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Amsar, Amsar, Khairuman Khairuman und Marlina Marlina. „Perancangan Alat Pendeteksi CO2 Menggunakan Sensor MQ-2 Berbasis Internet Of Thing“. METHOMIKA: Jurnal Manajemen Informatika dan Komputerisasi Akuntansi 4, Nr. 1 (01.04.2020): 73–79. http://dx.doi.org/10.46880/jmika.v4i1.143.

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Salah satu gas yang sangat berbahaya bagi kesehatan manusia adalah Gas CO2, untuk mengetahui kadar di tempat tertentu mengandung CO2 tanpa menggunakan alat bantu pendeteksi akan sulit dilakukan, karena Gas CO2 tersebut merupakan zat yang tidak dapat dilihat langsung oleh mata manusia, maka dalam penelitian ini dirancang sebuah alat pendeteksi CO2 yang dapat memberikan notifikasi kadar CO2 ke telegram berbasis Internet Of Things (IOT) . dalam peneltian ini alat yang digunakan untuk pengukuran kadar CO2 dengan menggunakan sensor MQ-2 untuk mendeteksi kadar dari karbon dioksida, sehingga kadar CO2 yang terdeteksi oleh sensor selanjutnya dikirim melalui jaringan IOT berbasis notifikasi via telegram, notifikasi pada telegram sebagai media pemberi inforamsi pada alat yang dibangun ini dengan lima kategori yaitu: baik, sedang, tidak sehat, sangat tidak sehat dan berbahaya, adapun hasil dari rentang diperoleh jika sensor MQ-2 mendeteksi karbon dioksida dengan rentang 0-50 ppm, maka kondisi udara baik, apabila sensor mendeteksi karbondioksida dengan rentang 51-100 ppm, maka kondisi udara sedang, apabila sensor mendeteksi karbondioksida dengan rentang 101-199 ppm, maka kondisi udara tidak sehat, apabila sensor mendeteksi karbondioksida dengan rentang 200-299 ppm, maka kondisi udara sangat tidak sehat, dan apabila sensor mendeteksi karbondioksida dengan rentang 300 ppm, maka notifikasi ke telegram berbahaya.

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Ji, Weiming, Zumei Zhu, Shunni Dong, Jingjing Nie und Binyang Du. „Optical Detection of Fe3+ Ions in Aqueous Solution with High Selectivity and Sensitivity by Using Sulfasalazine Functionalized Microgels“. Sensors 19, Nr. 19 (28.09.2019): 4223. http://dx.doi.org/10.3390/s19194223.

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A highly selective and sensitive optical sensor was developed to colorimetric detect trace Fe3+ ions in aqueous solution. The sensor was the sulfasalazine (SSZ) functionalized microgels (SSZ-MGs), which were fabricated via in-situ quaternization reaction. The obtained SSZ-MGs had hydrodynamic radius of about 259 ± 24 nm with uniform size distribution at 25 °C. The SSZ-MG aqueous suspensions can selectively and sensitively response to Fe3+ ions in aqueous solution at 25 °C and pH of 5.6, which can be quantified by UV-visible spectroscopy and also easily distinguished by the naked eye. Job’s plot indicated that the molar binding ratio of SSZ moiety in SSZ-MGs to Fe3+ was close to 1:1 with an apparent association constant of 1.72 × 104 M−1. A linear range of 0–12 μM with the detection limit of 0.110 μM (0.006 mg/L) was found. The obtained detection limit was much lower than the maximum allowance level of Fe3+ ions in drinking water (0.3 mg/L) regulated by the Environmental Protection Agency (EPA) of the United States. The existence of 19 other species of metal ions, namely, Ag+, Li+, Na+, K+, Ca2+, Ba2+, Cu2+, Ni2+, Mn2+, Pb2+, Zn2+, Cd2+, Co2+, Cr3+, Yb3+, La3+, Gd3+, Ce3+, and Bi3+, did not interfere with the detection of Fe3+ ions.

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Vasileva, Penka, Teodora Alexandrova und Irina Karadjova. „Application of Starch-Stabilized Silver Nanoparticles as a Colorimetric Sensor for Mercury(II) in 0.005 mol/L Nitric Acid“. Journal of Chemistry 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/6897960.

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A sensitive and selective Hg2+optical sensor has been developed based on the redox interaction of Hg2+with starch-coated silver nanoparticles (AgNPs) in the presence of 0.005 mol L−1HNO3. The relative intensity of the localized surface plasmon absorption band of AgNPs at 406 nm is linearly dependent on the concentration of Hg2+with positive slope for the concentration range 0–12.5 μg L−1and negative slope for the concentration range 25–500 μg L−1. Experiments performed demonstrated that metal ions (Na+, K+, Mg2+, Ca2+, Pb2+, Cu2+, Zn2+, Cd2+, Fe3+, Co2+, and Ni2+) do not interfere under the same conditions, due to the absence of oxidative activity of these ions, which guarantees the high selectivity of the proposed optical sensor towards Hg2+. The limits of detection and quantification were found to be 0.9 µg L−1and 2.7 µg L−1, respectively, and relative standard deviations varied in the range 9–12% for Hg content from 0.9 to 12.5 μg L−1and 5–9% for Hg levels from 25 to 500 μg L−1. The method was validated by analysis of CRM Estuarine Water BCR505. A possible mechanism of interaction between AgNPs and Hg2+for both concentration ranges was proposed on the basis of UV-Vis, TEM, and SAED analyses.

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Israelsson, Maria, Robert S. Siegel, Jared Young, Mimi Hashimoto, Koh Iba und Julian I. Schroeder. „Guard cell ABA and CO2 signaling network updates and Ca2+ sensor priming hypothesis“. Current Opinion in Plant Biology 9, Nr. 6 (Dezember 2006): 654–63. http://dx.doi.org/10.1016/j.pbi.2006.09.006.

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Astuti, Irnin Agustina Dwi, und Thoha Firdaus. „Analisis Kandungan CO2 Dengan Sensor dan Berbasis Logger Pro di Daerah Yogyakarta“. JIPFRI (Jurnal Inovasi Pendidikan Fisika dan Riset Ilmiah) 1, Nr. 1 (01.05.2017): 5–8. http://dx.doi.org/10.30599/jipfri.v1i1.118.

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Penelitian ini bertujuan untuk menganalisis kandungan CO2 di daerah Yogyakarta dengan menggunakan sensor CO2 dan logger pro. Kota Yogyakarta setiap tahunnya mengalami kepadatan penduduk yang menyebabkan pesatnya pemakaian kendaraan bermotor juga. Ini yang menyebabkan tingkat polusi udara di kota Yogyakarta juga semakin buruk akibat polusi kendaraan bermotor maupun industri. Kandungan CO2 yang seharusnya di atmosfer bumi sebesar 381 PPM. Dalam penelitian ini menganalisis kandungan CO2 di sepuluh tempat keramaian di Yogyakarta. Penelitian ini menggunakan sensor gas CO2 Vernier dan di analisis menggunakan software logger pro. Ketika sensor CO2 bekerja selama 5 menit akan muncul pulsa kandungan CO2 pada logger pro, kemudian dicari rata-rata kandungan CO2. Hasil penelitian ini dapat diperoleh uji kandungan CO2 yang paling tinggi adalah di daerah 0 KM Yogyakarta sebesar 973,2 PPM. Hasil ini melebihi nilai batas ambang rata-rata yang seharusnya di atmosfir bumi yaitu 381 PPM. Oleh karena itu perlu ditanami pepohonan dan mengurangi emisi kendaraan bermotor agar tingkat kandungan CO2 di kota Yogyakarta semakin menurun.

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Ma, Ying, Kittithat Promthaveepong und Nan Li. „CO2-Responsive Polymer-Functionalized Au Nanoparticles for CO2 Sensor“. Analytical Chemistry 88, Nr. 16 (26.07.2016): 8289–93. http://dx.doi.org/10.1021/acs.analchem.6b02133.

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Liao, Wei-Ming, Mei-Juan Wei, Jun-Ting Mo, Peng-Yan Fu, Ya-Nan Fan, Mei Pan und Cheng-Yong Su. „Acidity and Cd2+ fluorescent sensing and selective CO2 adsorption by a water-stable Eu-MOF“. Dalton Transactions 48, Nr. 14 (2019): 4489–94. http://dx.doi.org/10.1039/c9dt00539k.

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A new luminescent Eu-MOF from an amino-group modified tetracarboxylic acid ligand was designed, which could perform as an efficient pH acidity and Cd²⁺ PL sensor and CO₂ selector.

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Roxana Varlan, Anca, und Willy Sansen. „Micromachined conductometric p(CO2) sensor“. Sensors and Actuators B: Chemical 44, Nr. 1-3 (Oktober 1997): 309–15. http://dx.doi.org/10.1016/s0925-4005(97)00223-2.

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Wen, Chang Bao, Yong Feng Ju, Wan Lin Li, Wen Zheng Sun, Xin Xu, Yan Shao, Yan Ming Li und Li Min Wen. „Carbon Dioxide Gas Sensor Using SAW Device Based on ZnO Film“. Applied Mechanics and Materials 135-136 (Oktober 2011): 347–52. http://dx.doi.org/10.4028/www.scientific.net/amm.135-136.347.

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Carbon dioxide (CO2) gas sensor using surface acoustic wave (SAW) device based on Zinc oxide (ZnO) was developed and fabricated in this paper. The center frequency of SAW device is 203.528 MHz. The input and two output interdigital transducers (IDT) apodized by Morlet wavelet function can improve the side lobe rejection compared with uniform IDT. The ZnO film sensitive to CO2 gas was fabricated in measurement acoustic track of SAW device. Experiments results confirm that the CO2 gas sensor using SAW device based on ZnO film has good response characteristics to different concentrations CO2 gas. Furthermore, the CO2 gas sensor using SAW device based on ZnO film has good stability and linearity.

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Cao, Zheng, Yuyuan Chen, Qianpeng Zhang, Yanping Xia, Gang Liu, Dun Wu, Wenzhong Ma, Junfeng Cheng und Chunlin Liu. „Preparation and ion sensing property of the self-assembled microgels by QCM“. Nanofabrication 3, Nr. 1 (20.12.2017): 16–25. http://dx.doi.org/10.2478/nanofab-2017-0002.

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AbstractThe polyanion polystyrene sulfonate (PSS), the polycation poly (allylamine hydrochloride) (PAH), and the anionic poly (N-isopropylacrylamide-co-acrylic acid) [P(NIPAM-co-AA)] microgels were self-assembled onto the polyethylene imine (PEI) adsorbed gold surfaces of quartz crystal microbalance (QCM) because of the electrostatic attractions. The interactions of various metal particles including Ca2+, Bi3+, Cu2+, Zn2+, Ni2+, Sn2+, Co2+, and Cd2+with the obtained PEI/PSS/PAH/microgel layer in aqueous solutions were evaluated by QCM. The PEI/PSS/PAH/Microgel covered QCM sensor demonstrates the lowest detection limit of 0.1 ppm in aqueous solutions and the obviously linear connection between the frequency response and Ni2+concentration from 0.1 to 20 ppm, which is due to the complexation of Ni2+with the carboxyl groups of microgels. Atomic force microscopy (AFM) was used to reveal the morphology and stability of the self-assembled polyelectrolyte/microgel layer before and after adsorbing heavy metal ions. These self-assembled materials of polyelectrolyte/microgel layer will be helpful for manufacturing ion-selective materials for separation and identification purposes.

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Lehto, Juhani. „CO2 exakt einstellen“. UmweltMagazin 50, Nr. 08-09 (2020): 48–49. http://dx.doi.org/10.37544/0173-363x-2020-08-09-48.

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In den Niederlanden versuchen Forscher, den CO2-Gehalt in Gewächshäusern so einzustellen, dass etwa reichhaltig Gemüse und Obst geerntet werden kann. Im Mittelpunkt steht dabei ein CO2-Sensor einer finnischen Firma.

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Hsu, Hsiang-Chang, Tso-Sheng Hsieh, Tzu-Hsuan Huang, Liren Tsai und Chia-Chin Chiang. „Double Notched Long-Period Fiber Grating Characterization for CO2 Gas Sensing Applications †“. Sensors 18, Nr. 10 (22.09.2018): 3206. http://dx.doi.org/10.3390/s18103206.

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In this study, we applied a double-sided inductively coupled plasma (ICP) process to nanostructure long-period fiber grating (LPFG) in order to fabricate a double-notched LPFG (DNLPFG) sensor with a double-sided surface corrugated periodic grating. Using the sol-gel method, we also added thymol blue and ZnO to form a gas sensing layer, thus producing a DNLPFG CO2 gas sensor. The resulting sensor is the first double-sided etching sensor used to measure CO2. The experimental results showed that as the CO2 concentration increased, the transmission loss increased, and that the smaller the fiber diameter, the greater the sensitivity and the greater the change in transmission loss. When the diameter of the fiber was 32 μm (and the period was 570 μm) and the perfusion rate of CO2 gas was 15%, the maximum loss variation of up to 3.881 dB was achieved, while the sensitivity was 0.2146 dB/% and the linearity was 0.992. These results demonstrate that the DNLPG CO2 gas sensor is highly sensitive.

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Wang, Guangwei, Hongzhen Chen und Yuanhui Wu. „Influence of Heat Disturbance on the Performance of YSZ based CO2 Sensor with Compound of Li2CO3-BaCO3-Nd2O3 as Auxiliary Sensing Electrode“. Journal of New Materials for Electrochemical Systems 23, Nr. 4 (31.12.2020): 244–51. http://dx.doi.org/10.14447/jnmes.v23i4.a04.

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Suddenly changes and fluctuations of temperature often occur in the operational environment of the CO2 electrochemical sensor. In this work, the YSZ based potentiometric CO2 sensor having Li2CO3-BaCO3-Nd2O3 compound as its auxiliary sensing material was prepared. And the effects of several types of heat disturbance on the performance of this kind of sensor ware studied. The results indicate that the sensors after heat disturbances respond similarly with the sensor as prepared, which presents rapid and correct response for the change of CO2 concentration within the experimental range of 271-576802 ppm. The sensors, with or without heat disturbance, respond well as different extents of abrupt alteration of CO2 concentration occurs, and the EMF outputs recover rapidly as the concentration of CO2 change back to the base value. At the constant concentration of CO2, the EMFs of the sensors with or without heat treatment decrease slowly as the time increases, the reason for this phenomenon might be the accumulation of inert substances on the electrode interfaces and ageing of electrodes. However, heat treatment can improve the long-term stability of the sensor to some extent. Furthermore, this type of sensor works stably with the existence of water vapor (10%), it has similar response curve in the dry and water vapor content system. After some further investigations and improvements, it might be potentially applied in the practical combustion atmosphere.

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Qiao, Shunda, Yanchen Qu, Yufei Ma, Ying He, Yao Wang, Yinqiu Hu, Xin Yu, Zhonghua Zhang und Frank K. Tittel. „A Sensitive Carbon Dioxide Sensor Based on Photoacoustic Spectroscopy with a Fixed Wavelength Quantum Cascade Laser“. Sensors 19, Nr. 19 (26.09.2019): 4187. http://dx.doi.org/10.3390/s19194187.

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A photoacoustic spectroscopy (PAS) based carbon dioxide (CO2) sensor with a fixed wavelength quantum cascade laser (FW-QCL) was demonstrated. The emission wavelength of the FW-QCL at 4.42 μm in the mid-infrared spectral region matched a fundamental CO2 absorption line. Amplitude modulation of the laser intensity was used to match the resonant photoacoustic (PA) cell. The noise from the background was reduced with the correlation demodulation technique. The experimental results showed that the sensor had excellent signal stability and a concentration linear response. When the integration time was 1 s, a 1σ minimum detection limit (MDL) of 2.84 parts per million (ppm) for CO2 detection was achieved. The long-term stability of the sensor was evaluated by means of an Allan deviation analysis. With an integration time of ~100 s, the MDL was improved to 1 ppm. This sensor was also used to measure the CO2 concentration from some common emission sources, such as cigarette smoking, automobile exhaust, and the combustion of some carbon-containing materials, which confirmed the stability and robustness of the reported FW-QCL based CO2-PAS sensor system.

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Hannon, Ami, und Jing Li. „Solid State Electronic Sensors for Detection of Carbon Dioxide“. Sensors 19, Nr. 18 (06.09.2019): 3848. http://dx.doi.org/10.3390/s19183848.

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Detection of carbon dioxide (CO2) is very important for environmental, health, safety and space applications. We have studied novel multiwall carbon nanotubes (MWCNTs) and an iron oxide (Fe2O3) nanocomposite based chemiresistive sensor for detection of CO2 at room temperature. The sensor has been miniaturized to a chip size (1 cm × 2 cm). Good sensing performance was observed with a wide detection range of CO2 concentrations (100–6000 ppm). Structural properties of the sensing materials were characterized using Field-Emission Scanning Electron Microscopy, Fourier-Transform Infrared and Raman spectroscopies. The greatly improved sensitivity of the composite materials to CO2 can be attributed to the formation of a depletion layer at the p-n junction in an MWCNT/iron oxide heterostructure, and new CO2 gas molecules adhere to the high surface area of MWCNTs due to the concentration gradient. The test results showed that the CO2 sensor possesses fast response, compact size, ultra-low power consumption, high sensitivity and wide dynamic detection range.

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Omar, Nur, Yap Fen, Silvan Saleviter, Wan Daniyal, Nur Anas, Nur Ramdzan und Mohammad Roshidi. „Development of a Graphene-Based Surface Plasmon Resonance Optical Sensor Chip for Potential Biomedical Application“. Materials 12, Nr. 12 (14.06.2019): 1928. http://dx.doi.org/10.3390/ma12121928.

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The emergence of unintentional poisoning and uncontrolled vector diseases have contributed to sensor technologies development, leading to the more effective detection of diseases. In this study, we present the combination of graphene-based material with surface plasmon resonance technique. Two different graphene-based material sensor chips were prepared for rapid and quantitative detection of dengue virus (DENV) and cobalt ion (Co2+) as an example of typical metal ions. As the fundamental concept of surface plasmon resonance (SPR) sensor that relies on the refractive index of the sensor chip surface, this research focused on the SPR signal when the DENV and Co2+ interact with the graphene-based material sensor chip. The results demonstrated that the proposed sensor-based graphene layer was able to detect DENV and Co2+ as low as 0.1 pM and 0.1 ppm respectively. Further details in the detection and quantification of analyte were also discussed in terms of sensitivity, affinity, and selectivity of the sensor.

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Jia, Xiaoning, Joris Roels, Roel Baets und Gunther Roelkens. „On-Chip Non-Dispersive Infrared CO2 Sensor Based On an Integrating Cylinder“. Sensors 19, Nr. 19 (30.09.2019): 4260. http://dx.doi.org/10.3390/s19194260.

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In this paper, we propose a novel, miniaturized non-dispersive infrared (NDIR) CO2 sensor implemented on a silicon chip. The sensor has a simple structure, consisting of a hollow metallic cylindrical cavity along with access waveguides. A detailed analysis of the proposed sensor is presented. Simulation with 3D ray tracing shows that an integrating cylinder with 4 mm diameter gives an equivalent optical path length of 3 . 5 cm. The sensor is fabricated using Deep Reactive Ion Etching (DRIE) and wafer bonding. The fabricated sensor was evaluated by performing a CO2 concentration measurement, showing a limit of detection of ∼100 ppm. The response time of the sensor is only ∼2.8 s, due to its small footprint. The use of DRIE-based waveguide structures enables mass fabrication, as well as the potential co-integration of flip-chip integrated midIR light-emitting diodes (LEDs) and photodetectors, resulting in a compact, low-power, and low-cost NDIR CO2 sensor.

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Rahman, Haolia, Agus Sukandi, Nasruddin Nasruddin, Arnas Arnas und Remon Lapisa. „Mechanical Ventilation Control Based on Estimated occupancy using a Carbon Dioxide Sensor“. TEKNIK 41, Nr. 3 (23.11.2020): 232–38. http://dx.doi.org/10.14710/teknik.v41i3.33416.

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Ventilation is an important aspect to maintain good indoor air quality in a building. However, excessive ventilation causing high energy consumption of the HVAC system. The ASHRAE Standard provides a guideline to set the ventilation rate that depends on the occupants' number and space. Thus, quantification of the number of occupants is required to regulate the ventilation rate. In this study, the estimated number of occupants was estimated using a Bayesian MCMC method based on CO2 levels. The mass balance equation of the CO2 is used as a model for the calculation of Bayesian MCMC. The Bayesian method for estimating the occupants' number is tested in a 96,7 m3 office room equipped with a ventilation system. Thus the occupancy estimation and control of ventilation can be done in real-time. The test also includes conventional ventilation control based on CO2 levels directly without converting to the occupants' number. The ventilation rate based on the number of occupants at the present test chamber refers to ASHRAE 62.1. The test results show that ventilation controlled by the estimated number of occupants using the Bayesian method successfully conducted with ventilation rate per occupant closer to the ASHRAE 62.1 standard over conventional ventilation method

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Huber, J., C. Weber, A. Eberhardt und J. Wöllenstein. „Photoacoustic CO2-Sensor for Automotive Applications“. Procedia Engineering 168 (2016): 3–6. http://dx.doi.org/10.1016/j.proeng.2016.11.111.

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Wierzbicka, M., P. Pasierb und M. Rekas. „CO2 sensor studied by impedance spectroscopy“. Physica B: Condensed Matter 387, Nr. 1-2 (Januar 2007): 302–12. http://dx.doi.org/10.1016/j.physb.2006.04.020.

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Andò, B., S. Baglio, G. Di Pasquale, A. Pollicino, S. D’Agata, C. Gugliuzzo, C. Lombardo und G. Re. „An Inkjet Printed CO2 Gas Sensor“. Procedia Engineering 120 (2015): 628–31. http://dx.doi.org/10.1016/j.proeng.2015.08.755.

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Jia, Xiaoning, Joris Roels, Roel Baets und Gunther Roelkens. „A Miniaturised, Fully Integrated NDIR CO2 Sensor On-Chip“. Sensors 21, Nr. 16 (08.08.2021): 5347. http://dx.doi.org/10.3390/s21165347.

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In this paper, we present a fully integrated Non-dispersive Infrared (NDIR) CO2 sensor implemented on a silicon chip. The sensor is based on an integrating cylinder with access waveguides. A mid-IR LED is used as the optical source, and two mid-IR photodiodes are used as detectors. The fully integrated sensor is formed by wafer bonding of two silicon substrates. The fabricated sensor was evaluated by performing a CO2 concentration measurement, showing a limit of detection of ∼750 ppm. The cross-sensitivity of the sensor to water vapor was studied both experimentally and numerically. No notable water interference was observed in the experimental characterizations. Numerical simulations showed that the transmission change induced by water vapor absorption is much smaller than the detection limit of the sensor. A qualitative analysis on the long term stability of the sensor revealed that the long term stability of the sensor is subject to the temperature fluctuations in the laboratory. The use of relatively cheap LED and photodiodes bare chips, together with the wafer-level fabrication process of the sensor provides the potential for a low cost, highly miniaturized NDIR CO2 sensor.

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Qian, Jing, und Peter Saggau. „Modulation of Transmitter Release by Action Potential Duration at the Hippocampal CA3-CA1 Synapse“. Journal of Neurophysiology 81, Nr. 1 (01.01.1999): 288–98. http://dx.doi.org/10.1152/jn.1999.81.1.288.

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Qian, Jing and Peter Saggau. Modulation of transmitter release by action potential duration at the hippocampal CA3-CA1 synapse. J. Neurophysiol. 81: 288–298, 1999. Presynaptic Ca2+ influx through voltage-dependent Ca2+ channels triggers neurotransmitter release. Action potential duration plays a determinant role in the dynamics of presynaptic Ca2+ influx. In this study, the presynaptic Ca2+ influx was optically measured with a low-affinity Ca2+ indicator (Furaptra). The effect of action potential duration on Ca2+ influx and transmitter release was investigated. The K+ channel blocker 4-aminopyridine (4-AP) was applied to broaden the action potential and thereby increase presynaptic Ca2+ influx. This increase of Ca2+ influx appeared to be much less effective in enhancing transmitter release than raising the extracellular Ca2+ concentration. 4-AP did not change the Ca2+ dependence of transmitter release but instead shifted the synaptic transmission curve toward larger total Ca2+ influx. These results suggest that changing the duration of Ca2+ influx is not equivalent to changing its amplitude in locally building up an effective Ca2+ concentration near the Ca2+ sensor of the release machinery. Furthermore, in the presence of 4-AP, the N-type Ca2+ channel blocker ωCgTx GVIA was much less effective in blocking transmitter release. This phenomenon was not simply due to a saturation of the release machinery by the increased overall Ca2+ influx because a similar reduction of Ca2+ influx by application of the nonspecific Ca2+ channel blocker Cd2+ resulted in much more inhibition of transmitter release. Rather, the different potencies of ω-CgTx GVIA and Cd2+ in inhibiting transmitter release suggest that the Ca2+ sensor is possibly located at a distance from a cluster of Ca2+ channels such that it is sensitive to the location of Ca2+ channels within the cluster.

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Bellancini, Michele, Laura Cercenelli, Stefano Severi, Guido Comai und Emanuela Marcelli. „Development of a CO2 Sensor for Extracorporeal Life Support Applications“. Sensors 20, Nr. 13 (27.06.2020): 3613. http://dx.doi.org/10.3390/s20133613.

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Measurement of carbon dioxide (CO2) in medical applications is a well-established method for monitoring patient’s pulmonary function in a noninvasive way widely used in emergency, intensive care, and during anesthesia. Even in extracorporeal-life support applications, such as Extracorporeal Carbon Dioxide Removal (ECCO2R), Extracorporeal Membrane Oxygenation (ECMO), and cardiopulmonary by-pass (CPB), measurement of the CO2 concentration in the membrane oxygenator exhaust gas is proven to be useful to evaluate the treatment progress as well as the performance of the membrane oxygenator. In this paper, we present a new optical sensor specifically designed for the measurement of CO2 concentration in oxygenator exhaust gas. Further, the developed sensor allows measurement of the gas flow applied to the membrane oxygenator as well as the estimation of the CO2 removal rate. A heating module is implemented within the sensor to avoid water vapor condensation. Effects of temperature on the sensor optical elements of the sensors are disclosed, as well as a method to avoid signal–temperature dependency. The newly developed sensor has been tested and compared against a reference device routinely used in clinical practice in both laboratory and in vivo conditions. Results show that sensor accuracy fulfills the requirements of the ISO standard, and that is suitable for clinical applications.

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Peitzsch, Nicola, Günther Eberz und Dietrich H. Nies. „Alcaligenes eutrophus as a Bacterial Chromate Sensor“. Applied and Environmental Microbiology 64, Nr. 2 (01.02.1998): 453–58. http://dx.doi.org/10.1128/aem.64.2.453-458.1998.

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ABSTRACT In Alcaligenes eutrophus CH34, determinants encoding inducible resistance to chromate (chr) and to cobalt and nickel (cnr) are located adjacent to each other on plasmid pMOL28. To develop metal-sensing bacterial strains, a cloned part of plasmid pMOL28, which contains both determinants, was mutated with Tn5-lacZ. The chr::lacZfusions were specifically induced by chromium; cnr was induced best by Ni2+ but was also induced by Co2+, Mn2+, chromate, Cu2+, Cd2+, and Zn2+. The broad-host-range IncP1 plasmid pEBZ141, which contains achr::lux fusion, was constructed.A. eutrophus AE104(pEBZ141), carrying achr::lux transcriptional fusion, could be used as a biosensor for chromate when cultivated in glycerol as an optimal carbon source. Chromate and bichromate were the best inducers; induction by Cr3+ was 10 times lower, and other ions induced only a little or not at all. Interactions among induction of the chr resistance determinant, chromate reduction, chromate accumulation, and the sulfate concentration of the growth medium were demonstrated.

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MA, YU-PING, und ZHUO-HUA PAN. „Spontaneous regenerative activity in mammalian retinal bipolar cells: Roles of multiple subtypes of voltage-dependent Ca2+ channels“. Visual Neuroscience 20, Nr. 2 (März 2003): 131–39. http://dx.doi.org/10.1017/s0952523803202042.

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Patch-clamp recordings were used to investigate the properties of the regenerative activity in acutely isolated bipolar cells from the rat retina. Spontaneous, pacemaker-like membrane potential oscillations were observed in all rod bipolar cells and the majority of cone bipolar cells. The waveform of the regenerative potential was stereotypical but distinct among different bipolar cell groups, especially between rod and cone bipolar cells. The spontaneous activity was completely blocked by Co2+, suggesting that Ca2+ influx through voltage-dependent Ca2+ channels was required for initiating such activity. Ca2+-induced Ca2+ release, however, was not found to be involved. The spontaneous activity was also blocked by mibefradil, a T-type Ca2+ channel antagonist. In contrast, application of nimodipine, an L-type Ca2+ current antagonist, affected mainly the waveform of the regenerative potential. This study shows that mammalian retinal bipolar cells in isolation are also capable of generating Ca2+-dependent spontaneous regenerative potential. However, T-type Ca2+ channels appear to be essential for the initiation of the spontaneous activity in mammalian bipolar cells.

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Wang, Kunyang, Ligang Shao, Jiajin Chen, Guishi Wang, Kun Liu, Tu Tan, Jiaoxu Mei, Weidong Chen und Xiaoming Gao. „A Dual-Laser Sensor Based on Off-Axis Integrated Cavity Output Spectroscopy and Time-Division Multiplexing Method“. Sensors 20, Nr. 21 (30.10.2020): 6192. http://dx.doi.org/10.3390/s20216192.

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In this article, a compact dual-laser sensor based on an off-axis integrated-cavity output spectroscopy and time-division multiplexing method is reported. A complete dual-channel optical structure is developed and integrated on an optical cavity, which allows two distributed feedback (DFB) lasers operating at wavelengths of 1603 nm and 1651 nm to measure the concentration of CO2 and CH4, simultaneously. Performances of the dual-laser sensor are experimentally evaluated by using standard air (with a mixture of CO2 and CH4). The limit of detection (LoD) is 0.271 ppm and 1.743 ppb at a 20 s for CO2 and CH4, respectively, and the noise equivalent absorption sensitivities are 2.68 × 10−10 cm−1 Hz−1/2 and 3.88 × 10−10 cm−1 Hz−1/2, respectively. Together with a commercial instrument, the dual-laser sensor is used to measure CO2 and CH4 concentration over 120 h and verify the regular operation of the sensor for the detection of ambient air. Furthermore, a first-order exponential moving average algorithm is implemented as an effective digital filtering method to estimate the gas concentration.

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Fernández-Ramos, María Dolores, Fátima Mirza-Montoro, Luis Fermín Capitán-Vallvey und Isabel María Pérez de Vargas-Sansalvador. „Near Infrared Sensor to Determine Carbon Dioxide Gas Based on Ionic Liquid“. Coatings 11, Nr. 2 (30.01.2021): 163. http://dx.doi.org/10.3390/coatings11020163.

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In this study we present an NIR carbon dioxide gas sensor based on an inner filter process that includes an ionic liquid (IL), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), to improve its stability, dynamic behavior and lifetime, which are usually the main drawbacks with these sensors. The presence of CO2 causes a displacement of a simple boron-dipyrromethene-type fluorophore, azaBODIPY, as the pH indicator towards its acid form. This increases the emission intensity of Cr(III)-doped gadolinium aluminium borate (GAB) as the luminophore. The characterization of the prepared sensor was carried out and a discussion of the results is presented. The response and recovery times improved considerably, 23 and 49 s, respectively, with respect to the sensor without IL, at 60 and 120 s, respectively,. Additionally, the measurement range is extended when using IL, able in this case to measure in the complete range up to 100% CO2; without IL the measurement range is limited to 60% CO2. The detection limit ranges from 0.57% CO2 without IL to 0.26% CO2 when IL is added. The useful lifetime of the sensing membrane was 20 days for membranes with IL and only 6 days for membranes without IL, with the sensor always kept in the dark and without the need to maintain a special atmosphere.

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Han, Maeum, Soonyoung Jung, Yeonsu Lee, Daewoong Jung und Seong Ho Kong. „PEI-Functionalized Carbon Nanotube Thin Film Sensor for CO2 Gas Detection at Room Temperature“. Micromachines 12, Nr. 9 (30.08.2021): 1053. http://dx.doi.org/10.3390/mi12091053.

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In this study, a polyethyleneimine (PEI)-functionalized carbon nanotube (CNT) sensor was fabricated for carbon dioxide detection at room temperature. Uniform CNT thin films prepared using a filtration method were used as resistive networks. PEI, which contains amino groups, can effectively react with CO2 gas by forming carbamates at room temperatures. The morphology of the sensor was observed, and the properties were analyzed by scanning electron microscope (SEM), Raman spectroscopy, and fourier transform infrared (FT-IR) spectroscopy. When exposed to CO2 gas, the fabricated sensor exhibited better sensitivity than the pristine CNT sensor at room temperature. Both the repeatability and selectivity of the sensor were studied.

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Shibata, Yasukuni, Chikao Nagasawa, Makoto Abo, Makoto Inoue, Isamu Morino und Osamu Uchino. „Comparison of CO2 Vertical Profiles in the Lower Troposphere between 1.6 µm Differential Absorption Lidar and Aircraft Measurements Over Tsukuba“. Sensors 18, Nr. 11 (21.11.2018): 4064. http://dx.doi.org/10.3390/s18114064.

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A 1.6 μm differential absorption Lidar (DIAL) system for measurement of vertical CO2 mixing ratio profiles has been developed. A comparison of CO2 vertical profiles measured by the DIAL system and an aircraft in situ sensor in January 2014 over the National Institute for Environmental Studies (NIES) in Tsukuba, Japan, is presented. The DIAL measurement was obtained at an altitude range of between 1.56 and 3.60 km with a vertical resolution of 236 m (below 3 km) and 590 m (above 3 km) at an average error of 1.93 ppm. An in situ sensor for cavity ring-down spectroscopy of CO2 was installed in an aircraft. CO2 mixing ratio measured by DIAL and the aircraft sensor ranged from 398.73 to 401.36 ppm and from 399.08 to 401.83 ppm, respectively, with an average difference of −0.94 ± 1.91 ppm below 3 km and −0.70 ± 1.98 ppm above 3 km between the two measurements.

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Dam, V. A. T., M. A. Blauw, S. H. Brongersma und R. van Schaijk. „Gas Sensing with Atomic Layer Deposited Dielectric Thin Film“. Key Engineering Materials 605 (April 2014): 71–74. http://dx.doi.org/10.4028/www.scientific.net/kem.605.71.

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A metal-insulator-semiconductor (MIS) capacitor with La2O3 dielectric is proposedin this work as a sensor for measuring CO2 in air. In this device, a 10 nm thick La2O3 dielectriclayer, which serves as a CO2 sensitive material, was atomic-layer-deposited (ALD) on p-typesilicon. Change in the at band voltage (VFB) of the MIS capacitor due to the reactionbetween CO2 and oxide layer and its interfaces, is used as the gas sensitive parameter of thesensor. The deposition temperature for the La2O3 layer has been optimized for maximizingCO2 sensitivity. The process ow including post annealing (rapid thermal annealing) has beenoptimized to allow further possibility to integrate the sensor with CMOS read-out circuitries. The sensor shows a sensitivity of 84 mV per decade to CO2 in air in a concentration rangefrom 300-5000 ppm at ambient temperature with a response time (t90) of 34 minutes.

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Kodu, Margus, Tea Avarmaa, Hugo Mändar, Rando Saar und Raivo Jaaniso. „Structure-Dependent CO2 Gas Sensitivity of La2O2CO3 Thin Films“. Journal of Sensors 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/9591081.

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Rare earth oxycarbonates are potential candidate materials for constructing simple and low-cost chemiresistive sensors for monitoring carbon dioxide (CO2) gas in the living and working environment for personal comfort and health reasons. Also, measurement of CO2 concentrations is needed in many industrial processes. Specifically, sol-gel made nanoparticles of Nd and La oxycarbonates have been studied previously as novel CO2 gas sensor materials. In this paper, pulsed laser deposition of La oxycarbonate (La2O2CO3) thin films was studied and structural properties of obtained thin films were characterized. Also, CO2 gas sensing ability of synthesized films was evaluated. The films deposited under CO2 partial pressure in various conditions were all Raman amorphous. In situ or ex situ annealing procedure at high CO2 partial pressure was needed for obtaining crystalline La2O2CO3 films, whereby hexagonal and monoclinic polymorphs were obtained in ex situ and in situ processes, respectively. Sensor structure, made using in situ process, was sensitive to CO2 gas and showed relatively fast response and recovery characteristics.

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Mejia Quintero, Sully, Luiz Guedes Valente, Marcos de Paula Gomes, Hugo Gomes da Silva, Bernardo Caroli de Souza und Sergio Morikawa. „All-Fiber CO2 Sensor Using Hollow Core PCF Operating in the 2 µm Region“. Sensors 18, Nr. 12 (12.12.2018): 4393. http://dx.doi.org/10.3390/s18124393.

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A realistic implementation of an all-fiber CO2 sensor, using 74 cm of hollow core photonic crystal fiber (HC-PCF) as the cavity for light/gas interaction, has been implemented. It is based on CO2 absorbance in the 2 µm region. The working range is from 2% to 100% CO2 concentration at 1 atm total pressure and the response time obtained was 10 min. Depending on the concentration level, the sensor operates at one of three different wavelengths (2003.5 nm, 1997.0 nm and 1954.5 nm) to maintain a high sensitivity across all the working range.

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Kumar, Divyanshu, und Cheng-Shane Chu. „A Ratiometric Optical Dual Sensor for the Simultaneous Detection of Oxygen and Carbon Dioxide“. Sensors 21, Nr. 12 (12.06.2021): 4057. http://dx.doi.org/10.3390/s21124057.

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Simultaneous detection of carbon dioxide (CO2) and oxygen (O2) has attracted considerable interest since CO2 and O2 play key roles in various industrial and domestic applications. In this study, a new approach based on a fluorescence ratiometric referencing method was reported to develop an optical dual sensor where platinum (II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) complex used as the O2-sensitive dye, CdSe/ZnS quantum dots (QDs) combined with phenol red used as the CO2-sensitive dye, and CdSe/ZnS QDs used as the reference dye for the simultaneous detection of O2 and CO2. All the dyes were immobilized in a gas-permeable matrix poly (isobutyl methacrylate) (PolyIBM) and subjected to excitation using a 380 nm LED. The as-obtained distinct fluorescence spectral intensities were alternately exposed to analyte gases to observe changes in the fluorescence intensity. In the presence of O2, the fluorescence intensity of the Pt (II) complex was considerably quenched, while in the presence of CO2, the fluorescence intensity of QDs was increased. The corresponding ratiometric sensitivities of the optical dual sensor for O2 and CO2 were approximately 13 and 144, respectively. In addition, the response and recovery for O2 and CO2 were calculated to be 10 s/35 s and 20 s/60 s, respectively. Thus, a ratiometric optical dual gas sensor for the simultaneous detection of O2 and CO2 was successfully developed. Effects of spurious fluctuations in the intensity of external and excitation sources were suppressed by the ratiometric sensing approach.

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Yang, Lung Jieh. „Gas Permeation in Polydimethylsiloxane In Situ Monitoring by Silicon Pressure Sensors“. Advanced Materials Research 74 (Juni 2009): 113–16. http://dx.doi.org/10.4028/www.scientific.net/amr.74.113.

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This paper proposes a new way to detect the gas-leakage through PDMS. We use PDMS instead of Pyrex #7740 glass to seal the backside V-grooves of silicon pressure sensors. We put the packaged sensor into a pressurized chamber with CO2 at 300 psi. By observing the output voltage of the pressure sensor, the time history for CO2 permeating into the sensor cavity was easily found. In experiments, we use several PDMS membranes with different thickness, from 45 to 2000 μm, to package the pressure sensors and investigate the gas-leakage of PDMS. The gas leaking through PDMS is shown to be governed by diffusion mechanism, and the diffusion coefficients derived from CO2 leaking history is 2.2×10-9 m2/sec, matched with the previous work.

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