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1.
Small ; 20(30): e2312220, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38344893

RESUMO

Enzymatic activity depends on and can therefore be regulated by temperature. Selective modulation of the activity of different enzymes in one reaction pot would require temperature control local to each type of enzyme. It has been suggested previously that immobilization of enzyme on magnetic nanoparticles and exposing them to alternating magnetic field can enhance the reaction rate. This enhancement has been explained as being mediated by temperature increase caused by dissipation of the absorbed field energy in the form of heat. However, the possibility of spatially limiting this temperature increase on the microscale has been questioned. Here, it is investigated whether an activity enhancement of the enzyme sucrose phosphorylase immobilized on magnetic beads can be achieved, how this effect is related to the increase in temperature, and whether temperature differences within one reaction pot could be generated in this way. It is found that alternating magnetic field stimulation leads to increased enzymatic activity fully attributable to the increase of bulk temperature. Both theoretical analysis and experimental data indicate that no local heating near the particle surface takes place. It is further concluded that relevant increase of surface temperature can be obtained only with macroscopic, millimeter-sized, magnetic particles.


Assuntos
Ativação Enzimática , Temperatura , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Campos Magnéticos , Glucosiltransferases/metabolismo
2.
Small ; : e2402446, 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39194585

RESUMO

The loop-mediated isothermal amplification (LAMP) is widely used in the laboratory to facilitate rapid DNA or RNA detection with a streamlined operational process, whose properties are greatly dependent on the uniformity and rise rate of temperature in the reaction chambers and the design of the primers. This paper introduces a planar micro-heater equipped with an embedded micro-temperature sensor to realize temperature tunability at a low energy cost. Moreover, a control system, based on the Wheatstone bridge and proportional, integral, and derivative (PID) control, is designed to measure and adjust the temperature of the micro-heater. The maximum temperature rise rate of the designed micro-heater is ≈8 °C s-1, and it only takes ≈60 s to reach the target temperature. Furthermore, a designed plasmid, containing the B646L gene of African Swine Fever Virus (ASFV), and a set of specific primers, are used to combine with the designed micro-heating system to implement the LAMP reaction. Finally, the lateral flow assay is used to interpret the amplification results visually. This method can achieve highly sensitive and efficient detection of ASFV within 40 min. The sensitivity of this on-chip gene detection method is 8.4 copies per reaction, holding great potential for applications in DNA and RNA amplification.

3.
Dev Growth Differ ; 66(7): 372-380, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39187274

RESUMO

Experimental evolution of microbial cells provides valuable information on evolutionary dynamics, such as mutations that contribute to fitness gain under given selection pressures. Although experimental evolution is a promising tool in evolutionary biology and bioengineering, long-term culture experiments under multiple environmental conditions often impose an excessive workload on researchers. Therefore, the development of automated systems significantly contributes to the advancement of experimental evolutionary research. This review presents several specialized devices designed for experimental evolution studies, such as an automated system for high-throughput culture experiments, a culture device that generate a temperature gradient, and an automated ultraviolet (UV) irradiation culture device. The ongoing development of such specialized devices is poised to continually expand new frontiers in experimental evolution research.


Assuntos
Evolução Biológica , Raios Ultravioleta , Evolução Molecular Direcionada/métodos , Temperatura
4.
Chemistry ; 30(36): e202400134, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38361463

RESUMO

The construction of diverse and distinctive self-assembled structures in water, based on the control of the self-assembly processes of artificial small molecules, has received considerable attention in supramolecular chemistry. Cage-like perforated vesicles are distinctive and interesting self-assembled structures. However, the development of self-assembling molecules that can easily form perforated vesicles remains challenging. This paper reports a lower critical solution temperature (LCST) behavior-triggered self-assembly property of a 4-aminoquinoline (4-AQ)-based amphiphile with a tetra(ethylene glycol) chain, in HEPES buffer (pH 7.4). This property allows to form perforated vesicles after heating at 80 °C (> LCST). The self-assembly process of the 4-AQ amphiphile can be controlled by heating at 80 °C (> LCST) or 60 °C (< LCST). After cooling to room temperature, the selective construction of the perforated vesicles and nanofibers was achieved from the same 4-AQ amphiphile. Furthermore, the perforated vesicles exhibited slow morphological transformation into intertwined-like nanofibers but were easily restored by brief heating above the LCST.

5.
Crit Care ; 28(1): 170, 2024 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-38769582

RESUMO

AIMS AND SCOPE: The aim of this panel was to develop consensus recommendations on targeted temperature control (TTC) in patients with severe traumatic brain injury (TBI) and in patients with moderate TBI who deteriorate and require admission to the intensive care unit for intracranial pressure (ICP) management. METHODS: A group of 18 international neuro-intensive care experts in the acute management of TBI participated in a modified Delphi process. An online anonymised survey based on a systematic literature review was completed ahead of the meeting, before the group convened to explore the level of consensus on TTC following TBI. Outputs from the meeting were combined into a further anonymous online survey round to finalise recommendations. Thresholds of ≥ 16 out of 18 panel members in agreement (≥ 88%) for strong consensus and ≥ 14 out of 18 (≥ 78%) for moderate consensus were prospectively set for all statements. RESULTS: Strong consensus was reached on TTC being essential for high-quality TBI care. It was recommended that temperature should be monitored continuously, and that fever should be promptly identified and managed in patients perceived to be at risk of secondary brain injury. Controlled normothermia (36.0-37.5 °C) was strongly recommended as a therapeutic option to be considered in tier 1 and 2 of the Seattle International Severe Traumatic Brain Injury Consensus Conference ICP management protocol. Temperature control targets should be individualised based on the perceived risk of secondary brain injury and fever aetiology. CONCLUSIONS: Based on a modified Delphi expert consensus process, this report aims to inform on best practices for TTC delivery for patients following TBI, and to highlight areas of need for further research to improve clinical guidelines in this setting.


Assuntos
Lesões Encefálicas Traumáticas , Consenso , Técnica Delphi , Hipotermia Induzida , Humanos , Lesões Encefálicas Traumáticas/terapia , Lesões Encefálicas Traumáticas/fisiopatologia , Lesões Encefálicas Traumáticas/complicações , Hipotermia Induzida/métodos , Hipotermia Induzida/normas , Unidades de Terapia Intensiva/organização & administração , Pressão Intracraniana/fisiologia , Inquéritos e Questionários
6.
Crit Care ; 28(1): 20, 2024 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-38216985

RESUMO

BACKGROUND: The "Blood Pressure and Oxygenation Targets in Post Resuscitation Care" (BOX) trial investigated whether a low versus high blood pressure target, a restrictive versus liberal oxygenation target, and a shorter versus longer duration of device-based fever prevention in comatose patients could improve outcomes. No differences in rates of discharge from hospital with severe disability or 90-day mortality were found. However, long-term effects and potential interaction of the interventions are unknown. Accordingly, the objective of this study is to investigate both individual and combined effects of the interventions on 1-year mortality rates. METHODS: The BOX trial was a randomized controlled two-center trial that assigned comatose resuscitated out-of-hospital cardiac arrest patients to the following three interventions at admission: A blood pressure target of either 63 mmHg or 77 mmHg; An arterial oxygenation target of 9-10 kPa or 13-14 kPa; Device-based fever prevention administered as an initial 24 h at 36 °C and then either 12 or 48 h at 37 °C; totaling 36 or 72 h of temperature control. Randomization occurred in parallel and simultaneously to all interventions. Patients were followed for the occurrence of death from all causes for 1 year. Analyzes were performed by Cox proportional models, and assessment of interactions was performed with the interventions stated as an interaction term. RESULTS: Analysis for all three interventions included 789 patients. For the intervention of low compared to high blood pressure targets, 1-year mortality rates were 35% (138 of 396) and 36% (143 of 393), respectively, hazard ratio (HR) 0.92 (0.73-1.16) p = 0.47. For the restrictive compared to liberal oxygenation targets, 1-year mortality rates were 34% (135 of 394) and 37% (146 of 395), respectively, HR 0.92 (0.73-1.16) p = 0.46. For device-based fever prevention for a total of 36 compared to 72 h, 1-year mortality rates were 35% (139 of 393) and 36% (142 of 396), respectively, HR 0.98 (0.78-1.24) p = 0.89. There was no sign of interaction between the interventions, and accordingly, no combination of randomizations indicated differentiated treatment effects. CONCLUSIONS: There was no difference in 1-year mortality rates for a low compared to high blood pressure target, a liberal compared to restrictive oxygenation target, or a longer compared to shorter duration of device-based fever prevention after cardiac arrest. No combination of the interventions affected these findings. Trial registration ClinicalTrials.gov NCT03141099, Registered 30 April 2017.


Assuntos
Hipertensão , Parada Cardíaca Extra-Hospitalar , Humanos , Pressão Sanguínea , Parada Cardíaca Extra-Hospitalar/terapia , Coma , Ressuscitação
7.
Magn Reson Chem ; 62(4): 259-268, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37438985

RESUMO

The application of compact NMR instruments to hot flowing samples or exothermically reacting mixtures is limited by the temperature sensitivity of permanent magnets. Typically, such temperature effects directly influence the achievable magnetic field homogeneity and hence measurement quality. The internal-temperature control loop of the magnet and instruments is not designed for such temperature compensation. Passive insulation is restricted by the small dimensions within the magnet borehole. Here, we present a design approach for active heat shielding with the aim of variable temperature control of NMR samples for benchtop NMR instruments using a compressed airstream which is variable in flow and temperature. Based on the system identification and surface temperature measurements through thermography, a model predictive control was set up to minimise any disturbance effect on the permanent magnet from the probe or sample temperature. This methodology will facilitate the application of variable-temperature shielding and, therefore, extend the application of compact NMR instruments to flowing sample temperatures that differ from the magnet temperature.

8.
Sensors (Basel) ; 24(9)2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38732983

RESUMO

Sensors based on solidly mounted resonators (SMRs) exhibit a good set of properties, such as high sensitivity, fast response, low resolution limit and low production cost, which makes them an appealing technology for sensing applications. However, they can suffer from cross-sensitivity issues, as their response can be altered by undesirable ambient factors, such as temperature and humidity variations. In this work we propose a method to discriminate humidity variations from the general frequency response using an SMR specifically manufactured to operate in a dual-mode (displaying two close resonances). The two modes behave similarly towards humidity changes (-1.94 kHZ/(%RH)) for resonance one and -1.62 kHZ/(%RH) for resonance two), whereas their performance under temperature changes is significantly different, displaying 2.64 kHZ/°C for resonance one and 34.21 kHZ/°C for resonance two. This allows for the decoupling process to be carried out in a straightforward manner. Frequency response is tracked under different humidity conditions, in the -20 °C to room temperature region, proving that this behavior is reproducible in any given environment.

9.
Sensors (Basel) ; 24(2)2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38257692

RESUMO

For tumors wherein cancer cells remain in the tissue after colorectal cancer surgery, a hyperthermic anticancer agent is injected into the abdominal cavity to necrotize the remaining cancer cells with heat using a hyperthermic intraperitoneal chemotherapy system. However, during circulation, the processing temperature is out of range and the processing result is deteriorated. This paper proposes a look-up table (LUT) module design method that can stably maintain the processing temperature range during circulation via feedback. If the temperature decreases or increases, the LUT transmits a command signal to the heat exchanger to reduce or increase heat input, thereby maintaining the treatment temperature range. The command signal for increasing and decreasing heat input is Tp and Ta, respectively. The command signal for the treatment temperature range is Ts. If drug temperatures below 41 and above 43 °C are input to the LUT, it sends a Tp or Ta signal to the heat exchanger to increase or decrease the input heat, respectively. If the drug's temperature is 41-43 °C, the LUT generates a Ts signal and proceeds with the treatment. The proposed system can automatically control drug temperature using temperature feedback to ensure rapid, accurate, and safe treatment.


Assuntos
Quimioterapia Intraperitoneal Hipertérmica , Julgamento , Humanos , Temperatura , Temperatura Alta , Febre
10.
Sensors (Basel) ; 24(15)2024 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-39124067

RESUMO

Laser metal deposition (LMD) is a technology for the production of near-net-shape components. It is necessary to control the manufacturing process to obtain good geometrical accuracy and metallurgical properties. In the present study, a closed-loop control method of melt pool temperature for the deposition of small Ti6Al4V blocks in open environment was proposed. Based on the developed melt pool temperature sensor and deposition height sensor, a closed-loop control system and proportional-integral (PI) controller were developed and tested. The results show that with a PI temperature controller, the melt pool temperature tends to the desired value and remains stable. Compared to the deposition block without the controller, a flatter surface and no oxidation phenomenon are obtained with the controller.

11.
Molecules ; 29(14)2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-39064840

RESUMO

Dynamic bonds can facilitate reversible formation and dissociation of connections in response to external stimuli, endowing materials with shape memory and self-healing capabilities. Temperature is an external stimulus that can be easily controlled through heat. Dynamic covalent bonds in response to temperature can reversibly connect, exchange, and convert chains in the polymer. In this review, we introduce dynamic covalent bonds that operate without catalysts in various temperature ranges. The basic bonding mechanism and the kinetics are examined to understand dynamic covalent chemistry reversibly performed by equilibrium control. Furthermore, a recent synthesis method that implements dynamic covalent coupling based on various polymers is introduced. Dynamic covalent bonds that operate depending on temperature can be applied and expand the use of polymers, providing predictions for the development of future smart materials.

12.
Crit Care ; 27(1): 35, 2023 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-36691075

RESUMO

BACKGROUND: Temperature control is recommended after out of hospital cardiac arrest (OHCA) by international guidelines. This survey aimed to investigate current clinical practice and areas of uncertainty. METHODS: Online survey targeting members of three medical emergency and critical care societies in Germany (April 21-June 6, 2022) assessing post-cardiac arrest temperature control management. RESULTS: Of 341 completed questionnaires 28% (n = 97) used temperature control with normothermic target and 72% (n = 244) temperature control with hypothermic target. The definition of fever regarding patients with cardiac arrest ranged from ≥ 37.7 to 39.0 °C. Temperature control was mainly started in the ICU (80%, n = 273) and most commonly core cooling (74%, n = 254) and surface cooling (39%, n = 134) with feedback were used. Temperature control was maintained for 24 h in 18% (n = 61), 48 h in 28% (n = 94), 72 h in 42% (n = 143) and longer than 72 h in 13% (n = 43). 7% (n = 24) were using different protocols for OHCA with initial shockable and non-shockable rhythm. Additional 14% (n = 48) were using different temperature control protocols after in-hospital cardiac arrest (IHCA) compared with OHCA. Overall, 37% (n = 127) changed practice after the publication of the ERC-2021 guidelines and 33% (n = 114) after the recent publication of the revised ERC-ESICM guideline on temperature control. CONCLUSIONS: One-third of the respondents changed clinical practice since recent guideline update. However, a majority of physicians further trusts in temperature control with a hypothermic target. Of interest, 14% used different temperature control strategies after IHCA compared with OHCA and 7% for shockable and non-shockable initial rhythm. A more individualized approach in post resuscitation care may be warranted.


Assuntos
Reanimação Cardiopulmonar , Hipotermia Induzida , Parada Cardíaca Extra-Hospitalar , Humanos , Adulto , Reanimação Cardiopulmonar/métodos , Temperatura , Parada Cardíaca Extra-Hospitalar/terapia , Alemanha , Inquéritos e Questionários , Hipotermia Induzida/métodos
13.
Pacing Clin Electrophysiol ; 46(12): 1536-1545, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37957924

RESUMO

BACKGROUND AND AIMS: The safety evaluation of TactiFlex, a novel contact-force sensing catheter with a flexible 4-mm tip irrigated through laser-cut kerfs, has been ongoing. This study aimed to verify the safety of this type of catheter. METHODS: Study 1: Radiofrequency (RF) applications at a range of powers (30-50 W), contact forces (10-20 g), and durations (10-60 s) using perpendicular/parallel catheter orientation with half-normal (HNS) or normal saline irrigation were compared between TactiFlex (4-mm tip) and TactiCath (3.5-mm tip) with temperature-controlled mode in excised porcine hearts. Study 2: The relation between RF applications using TactiFlex and the incidence of steam-pops in the real clinical cases were examined. RESULTS: Study-1: 576 RF lesions were examined. TactiFlex demonstrated a significantly lower risk of steam-pops (5[1.7%] vs. 59[20.5%], p < .0001). Compared to 3.5-mm-tip catheter (TactiCath), 4-mm-tip catheter (TactiFlex) produced smaller lesion volume at perpendicular (193[98-554]mm3 vs. 263[139-436]mm3 , p < .0001), but relatively similar lesion volume at parallel contact (243[105-443]mm3 vs. 278[180-440]mm3 , p = .06). HNS-irrigation tended to increase the lesion volume in both catheters and to increase the incidence of steam-pops with TactiCath, but not with TactiFlex. The cut-off value of %impedance-drop ( = absolute impedance-drop/initial impedance) of 20% predicted steam-pops with a sensitivity = 100% and specificity = 89.6% in TactiFlex. Study-2: 5496 RF applications in 84 patients (51AFs/8ATs/3AVNRTs/4AVRTs/17PVCs/4VTs) using TactiFlex were analyzed. Four steam-pops (0.07%) in three patients with pericardial effusion were observed (%impedance-drop = 24%/26%/29%/35%, respectively). The cut-off value of %impedance-drop = 20%, derived from ex-vivo study, showed sensitivity = 100% and specificity = 90.1% in detecting steam-pops. CONCLUSION: TactiFlex reduced the risk of steam-pops than TactiCath. %impedance-drop ≤ 20% may be reasonable for safely use with a sufficient safety margin. For 4-mm-tip catheter, parallel-contact may be recommended for larger lesion creation.


Assuntos
Ablação por Cateter , Vapor , Humanos , Animais , Suínos , Irrigação Terapêutica , Desenho de Equipamento , Catéteres
14.
Cryobiology ; 110: 49-55, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36509162

RESUMO

The outcome of cardiac arrest is worse when there is fever after spontaneous circulation is restored (ROSC). The purpose of this study was to investigate the mechanism of post-ROSC cardiac dysfunction after hyperthermia treatment and the effects of temperature control. Twenty-four male Bama minipigs were randomized into 3 groups (8 per group): CPR + controlled normothermia (CN), CPR + hyperthermia (HT), and CPR + therapeutic mild hypothermia (TMH). Defibrillation was given to pigs with ventricular fibrillation after 8 min of untreated fibrillation. Subsequently, these animals received the post-ROSC treatments of hyperthermia (38 °C), controlled normothermia (37 °C) or hypothermia (33 °C) according to the groups. Hemodynamic parameters, left ventricular ejection fraction, blood samples and myocardial tissues were assessed. At 24 h after the post-ROSC treatments, the pigs treated with hyperthermia showed increments in heart rate and plasma cardiac troponin I, and decreases in mean arterial pressure, cardiac index, and left ventricular ejection fraction, compared to those with the controlled normothermia pigs. However, the deterioration of the above parameters can be attenuated by TMH. The pigs in the TMH group also had a reduced percentage of apoptotic cardiomyocytes, an increased anti-apoptotic Bcl-2/Bax ratio and a decreased caspase-3 activity in myocardium, as compared with both controlled normothermia and hyperthermia pigs. In conclusion, hyperthermia is associated with a worse myocardial dysfunction. TMH improves hyperthermia-induced myocardial dysfunction by attenuating apoptosis in a porcine model of cardiac arrest.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca , Hipertermia Induzida , Hipotermia Induzida , Hipotermia , Suínos , Animais , Masculino , Volume Sistólico , Hipotermia/terapia , Temperatura , Porco Miniatura , Função Ventricular Esquerda , Criopreservação/métodos
15.
Am J Emerg Med ; 64: 1-7, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36435004

RESUMO

Therapeutic hypothermia was recommended as the only neuroprotective treatment in comatose patients after return of spontaneous circulation (ROSC). With new evidence suggesting a similar neuroprotective effect of 36 °C and 33 °C, the term "therapeutic hypothermia" was substituted by "targeted temperature management" in 2011, which in turn was replaced by the term "temperature control" in 2022 because of new evidence of the similar effects of target normothermia and 33 °C. However, there is no clear consensus on the efficacy of therapeutic hypothermia. In this article, we provide an overview of the recent evidence from basic and clinical research related to therapeutic hypothermia and re-evaluate its application as a post-ROSC neuroprotective intervention in clinical settings.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca , Hipotermia Induzida , Hipotermia , Humanos , Parada Cardíaca/terapia , Hipotermia/terapia , Coma/terapia
16.
Sensors (Basel) ; 23(15)2023 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-37571689

RESUMO

In a laboratory environment, in order to test the attitude recognition capability and accuracy of the satellite attitude sensor-the infrared Earth sensor-the infrared Earth simulator is fixed on a five-axis turntable to enable multi-angle testing. In the past, the temperature control system of the Earth simulator was water cooled, which not only affected the working accuracy of the Earth simulator but also affected its size and portability and made it more difficult to use on the turntable. Therefore, we designed a cooling method for the cold plate based on semiconductor cooling technology combined with air cooling, and we designed a fuzzy PID control algorithm to accurately control the temperature according to this cooling method. In this article, we use SOLIWORKS to build the system model for the system and use the ANAYS Workbench to perform temperature analysis of the Earth simulator. The results show that the cold plate temperature can be maintained at 20.089 °C when the hot plate temperature is 85 °C. The overall temperature uniformity of the hot plate is better than ±0.3 °C, which meets the index requirements of the Earth simulator. We found that this cooling method can replace water cooling, giving the simulator the advantage of being miniaturized, and it can be adaptable to the turntable, which can be widely used in various sizes of Earth simulators and in various complex environments and operating conditions.

17.
Sensors (Basel) ; 23(13)2023 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-37447834

RESUMO

This study addresses the pressing issue of energy consumption and efficiency in the Kingdom of Saudi Arabia (KSA), a region experiencing growing demand for energy resources. Temperature control plays a vital role in achieving energy efficiency; however, traditional control systems may struggle to adapt to the non-linear and time-varying characteristics of the problem. To tackle this challenge, a fuzzy petri net (FPN) controller is proposed as a more suitable solution that combines fuzzy logic (FL) and petri nets (PN) to model and simulate complex systems. The main objective of this research is to develop an intelligent energy-saving framework that integrates advanced methodologies and air conditioning (AC) systems to optimize energy utilization and create a comfortable indoor environment. The proposed system incorporates user identification to authorize individuals who can set the temperature, and FL combined with PN is utilized to monitor and transmit their preferred temperature settings to a PID controller for adjustment. The experimental findings demonstrate the effectiveness of integrating the FPN controller with a convertible frequency AC compressor in significantly reducing energy consumption by 94% compared to using the PN controller alone. The utilization of the PN controller alone resulted in a 25% reduction in energy consumption. Conversely, employing a fixed-frequency compressor led to a 40% increase in energy consumption. These results emphasize the advantages of integrating FL into the PN model, as it effectively reduces energy consumption by half, highlighting the potential of the proposed approach for enhancing energy efficiency in AC systems.


Assuntos
Lógica Fuzzy , Humanos , Temperatura , Arábia Saudita
18.
Sensors (Basel) ; 23(22)2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-38005588

RESUMO

A hydrogen maser is a high-precision time measurement instrument with high frequency stability and low frequency drift, which is widely used in satellite navigation, ground time keeping, frequency measurement, and other fields. An active hydrogen maser (AHM) is better than the current space passive hydrogen maser (PHM) in orbit in terms of its frequency stability and drift rate, but it has the disadvantages of large volume and weight. To further reduce the volume and weight of the circuit, this paper demonstrates a digital circuit control system based on a field-programmable gate array (FPGA). It uses digital temperature control, digital detectors, digital down-conversion, digital phase-locked loops, and other digital methods for temperature control, cavity auto-tuning, and crystal phase locking, which improve the integration and flexibility of the circuit system. Meanwhile, a tuning method based on hydrogen flow is proposed, which effectively solves the problem of fluctuations in hydrogen maser resonance frequency with changes in the external environment. Our experimental results show that the designed digital circuit control system meets the requirements of an oven-controlled crystal oscillator (OCXO) loop and a cavity loop. Its frequency stability can reach 2.6×10-13/1 s and 1.4×10-15/10,000 s, which is close to the stability index of ground active hydrogen maser. This scheme has certain practical engineering value, and can be used in the design of hydrogen masers for next-generation space navigation satellites, deep space exploration, and space stations.

19.
Sensors (Basel) ; 23(18)2023 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-37765775

RESUMO

The ability to simultaneously heat and image samples using transmitted light is crucial for several biological applications. However, existing techniques such as heated stage microscopes, thermal cyclers equipped with imaging capabilities, or non-contact heating systems are often bulky, expensive, and complex. This work presents the development and characterization of a Miniaturized Optically-clear Thermal Enclosure (MOTE) system-an open-source, inexpensive, and low-powered modular system-capable of convectively heating samples while simultaneously imaging them with transmitted light. We develop and validate a computational fluid dynamics (CFD) model to design and optimize the heating chamber. The model simulates velocity and temperature profiles within the heating chamber for various chamber materials and sizes. The computational model yielded an optimal chamber dimension capable of achieving a stable temperature ranging from ambient to 95 °C with a spatial discrepancy of less than 1.5 °C, utilizing less than 8.5 W of power. The dual-functionality of the MOTE system, enabling synchronous heating and transmitted light imaging, was demonstrated through the successful execution of paper-based LAMP reactions to detect λ DNA samples in real-time down to 10 copies/µL of the target concentration. The MOTE system offers a promising and flexible platform for various applications, from molecular diagnostics to biochemical analyses, cell biology, genomics, and education.

20.
J Environ Manage ; 325(Pt A): 116396, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36244280

RESUMO

In this work, nanomaterials of the SrMoO4/g-C3N4 heterostructure were synthesized in a single step by the sonochemical method with controlled temperatures. Structural and morphological investigations indicate the formation of heterojunctions, revealing the presence of g-C3N4 (CN) in the heterostructures and an interface region between the phases. Optical analyzes show broadening of the wavelength absorption range and a decrease in the photoluminescence (PL) intensity of the heterojunctions compared to the CN emission spectrum, proving a decrease in the recombination of the photogenerated charges. The results of the photocatalytic tests indicate that the insertion of CN promoted photocatalytic degradation of the Methylene Blue (MB), Rhodamine B (RhB) and Crystal Violet (CV) organic contaminants, up to 99.58%, 100% and 98.65%, respectively. The mixture of dyes used and reuse cycles was performed to analyze the applicability of the compounds in a real situation.

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