Low-temperature effect
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Chlorosomes from green photosynthetic bacteria belong to the most effective light-harvesting antennas found in nature. Quinones incorporated in bacterichlorophyll (BChl) c aggregates inside chlorosomes play an important redox-dependent photo-protection role against oxidative damage of bacterial reaction centers. Artificial BChl c aggregates with and without quinones were prepared. We applied hole-burning spectroscopy and steady-state absorption and emission techniques at 1.9 K and two different redox potentials to investigate the role of quinones and redox potential on BChl c aggregates at low temperatures. We show that quinones quench the excitation energy in a similar manner as at room temperature, yet the quenching process is not as efficient as for chlorosomes. Interestingly, our data suggest that excitation quenching partially proceeds from higher excitonic states competing with ultrafast exciton relaxation. Moreover, we obtained structure-related parameters such as reorganization energies and inhomogeneous broadening of the lowest excited state, providing experimental ground for theoretical studies aiming at designing plausible large-scale model for BChl c aggregates including disorder.
This paper presents the results of lab-scale experiments on low temperature thermal pre-treatment (less than 100 °C) prior to anaerobic digestion of sewage sludge. Two heating ways, microwave heating (MH) and conventional heating (CH), and two types of sludge, primary and waste activated sludge, were compared under the same experimental conditions. The degree of solubilisation produced by MH and CH up to 72, 82 and 93 °C was firstly estimated. For both types of heating, increase in soluble chemical oxygen demand (COD) caused by the pre-treatment was about 14% on waste activated sludge and only 3% on primary sludge. The final temperature of 72 °C resulted as the most cost-effective in terms of additional soluble COD per unit of energy required. Subsequently, five series of biochemical methane potential mesophilic assays were run in 120 mL serum bottles on sludge samples pre-treated at 72 °C. When compared with control reaction vessels, no significant differences were noticed in net methane production of pre-treated primary sludge, whereas a relevant increase occurred regarding the pre-treated waste activated sludge. It was also observed that the trend of methane content in biogas during the batch tests can be described by a second order polynomial.
Cold acclimation modifies the photosynthetic machinery and enables plants to survive at sub-zero temperatures, whereas in warm habitats, many species suffer even at non-freezing temperatures. We have measured chlorophyll a fluorescence (ChlF) and CO2 assimilation to investigate the effects of cold acclimation, and of low temperatures, on a cold-sensitive Arabidopsis thaliana accession C24. Upon excitation with low intensity (40 µmol photons m- 2 s- 1) ~ 620 nm light, slow (minute range) ChlF transients, at ~ 22 °C, showed two waves in the SMT phase (S, semi steady-state; M, maximum; T, terminal steady-state), whereas CO2 assimilation showed a linear increase with time. Low-temperature treatment (down to - 1.5 °C) strongly modulated the SMT phase and stimulated a peak in the CO2 assimilation induction curve. We show that the SMT phase, at ~ 22 °C, was abolished when measured under high actinic irradiance, or when 3-(3, 4-dichlorophenyl)-1, 1- dimethylurea (DCMU, an inhibitor of electron flow) or methyl viologen (MV, a Photosystem I (PSI) electron acceptor) was added to the system. Our data suggest that stimulation of the SMT wave, at low temperatures, has multiple reasons, which may include changes in both photochemical and biochemical reactions leading to modulations in non-photochemical quenching (NPQ) of the excited state of Chl, "state transitions," as well as changes in the rate of cyclic electron flow through PSI. Further, we suggest that cold acclimation, in accession C24, promotes "state transition" and protects photosystems by preventing high excitation pressure during low-temperature exposure.
Nízkoteplotní plazma produkované stejnosměrnými elektrickými výboji se jeví jako vhodný prostředek inaktivace plísní. Tato teze je dokumentována na přehledu výsledků dosažených studiemi in vitro i in vivo. Fungi jsou sice na působení plazmatu méně citlivé než bakterie a citlivost jejich jednotlivých druhů je různá, původci dermatomykóz jsou však inaktivováni expozicemi do 25 minut. Na arteficiálně infikovaných morčatech bylo prokázáno jak zkrácení doby onemocnění, tak i snížení počtu zárodků infekčního agens. Použití plazmatu v dermatologii je dokumentováno i na případu z humánní medicíny. Pro expozici pokožky plazmatu nebyly zjištěny žádné nepříznivé vedlejší účinky.
Low temperature plasma produced by direct current electric discharges seems to be a useful tool for inactivation of fungi. This thesis is documented in this review of previous results of in vitro and in vivo studies. Fungi are less sensitive to plasma exposure than bacteria and their sensitivity differs among strains, causative agents of dermatomycoses, however, are inactivated within 25 minutes. Both shortening disease and reducing the number of germs was proved on artificially infected guinea pigs. The use of plasma in dermatology is also documented on a case of human medicine. The exposure of skin by plasma exhibits no adverse side effects.
- MeSH
- dermatomykózy * terapie MeSH
- experimenty na zvířatech MeSH
- lidé MeSH
- mladý dospělý MeSH
- morčata MeSH
- plazmové plyny * aplikace a dávkování terapeutické užití MeSH
- počet mikrobiálních kolonií MeSH
- techniky in vitro MeSH
- tinea terapie MeSH
- výsledek terapie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mladý dospělý MeSH
- morčata MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- kazuistiky MeSH
- práce podpořená grantem MeSH
The fungicidal effect of low-temperature plasma generated by positive direct current discharge and its influence on the growth dynamics was evaluated on three micromycete species and yeast in water suspensions. The fungicidal effect was lower than analogous bactericidal effect and differs substantially among various fungal species. Together with the cidal effects, the slower growth of exposed fungal spores was observed.
This paper reports the substitution of polyolefin backbone binder components with low melting temperature carnauba wax for powder injection moulding applications. The effect of various binder compositions of Al₂O₃ feedstock on thermal degradation parameters is investigated by thermogravimetric analysis. Within the experimental framework 29 original feedstock compositions were prepared and the superiority of carnauba wax over the polyethylene binder backbone was demonstrated in compositions containing polyethylene glycol as the initial opening agent and governing the proper mechanism of the degradation process. Moreover, the replacement of synthetic polymer by the natural wax contributes to an increase of environmental sustainability of modern industrial technologies.
INTRODUCTION: Magnetic nanoparticles (NPs) represent a tool for use in magnetic resonance imaging (MRI)-guided thermoablation of tumors using an external high-frequency (HF) magnetic field. To avoid local overheating, perovskite NPs with a lower Curie temperature (T c) were proposed for use in thermotherapy. However, deposited power decreases when approaching the Curie temperature and consequently may not be sufficient for effective ablation. The goal of the study was to test this hypothesis. METHODS: Perovskite NPs (T c =66°C-74°C) were characterized and tested both in vitro and in vivo. In vitro, the cells suspended with NPs were exposed to a HF magnetic field together with control samples. In vivo, a NP suspension was injected into a induced tumor in rats. Distribution was checked by MRI and the rats were exposed to a HF field together with control animals. Apoptosis in the tissue was evaluated. RESULTS AND DISCUSSION: In vitro, the high concentration of suspended NPs caused an increase of the temperature in the cell sample, leading to cell death. In vivo, MRI confirmed distribution of the NPs in the tumor. The temperature in the tumor with injected NPs did not increase substantially in comparison with animals without particles during HF exposure. We proved that the deposited power from the NPs is too small and that thermoregulation of the animal is sufficient to conduct the heat away. Histology did not detect substantially higher apoptosis in NP-treated animals after ablation. CONCLUSION: Magnetic particles with low T c can be tracked in vivo by MRI and heated by a HF field. The particles are capable of inducing cell apoptosis in suspensions in vitro at high concentrations only. However, their effect in the case of extracellular deposition in vivo is questionable due to low deposited power and active thermoregulation of the tissue.
- MeSH
- ablace přístrojové vybavení metody MeSH
- indukovaná hypertermie metody MeSH
- kontrastní látky * chemie farmakokinetika MeSH
- magnetická rezonanční tomografie přístrojové vybavení metody MeSH
- magnety MeSH
- nádorové buněčné linie MeSH
- nanočástice * chemie MeSH
- oxid křemičitý chemie MeSH
- oxidy chemie MeSH
- potkani Wistar MeSH
- sloučeniny vápníku chemie MeSH
- suspenze MeSH
- teplota MeSH
- titan chemie MeSH
- xenogenní modely - testy protinádorové aktivity MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The inactivation of Schistosoma mansoni cercariae and miracidia was achieved by exposure to plasma produced by the positive, negative, and axial negative corona discharges. The positive discharge appeared as the most effective, causing the death of cercariae and miracidia within 2-3 min of exposure. The negative discharge was less effective, and the axial discharge was ineffective. The water pre-activated (PAW) by the discharges showed similar efficiency, with the exception of the significantly effective PAW activated with axial discharge. These facts, together with the observation of various reactions among plasma-damaged schistosomes, suggest that the mechanisms of inactivation by different types of discharges are different.
- Publikační typ
- časopisecké články MeSH
AIMS: The ultra-low-temperature cryoablation (ULTC) ablation system using -196°C N2 cryogen has been reported to create lesions with freeze duration-dependent depth titratable to over 10 mm with minimum attenuation by scar. Cryocure-VT (NCT04893317) was a first-in-human clinical trial evaluating the safety and efficacy of a novel, purpose-built ULTC catheter in endocardial ablation of scar-dependent ventricular tachycardias (VTs). METHODS AND RESULTS: This prospective, multi-centre study enrolled patients referred for de novo or second ablations of recurrent monomorphic VT of both ischaemic and non-ischaemic aetiologies. Primary safety and efficacy endpoints of the study were freedom from device- or procedure-related major adverse events (MAEs) up to 30 days post-ablation, acute non-inducibility of clinical VTs at the end of the procedure, and freedom from sustained VT or implantable defibrillator intervention at 6 months. Ultra-low-temperature cryoablation was performed in 64 patients (age 67 ± 11 years, 78% ischaemic, ejection fraction = 35 ± 10%) at 9 centres. The primary acute effectiveness endpoint was achieved in 94% (51/54) of patients in whom post-ablation induction was attempted. There were no protocol-defined MAEs; four procedure-related serious adverse events resolved without clinical sequelae. At 6-month follow-up, 38 patients (60.3%) remained VT-free, and freedom from defibrillator shock was 81.0%, with no significant difference between ischaemic and non-ischaemic cohorts. In 47 patients with defibrillator for at least 6 months prior to the ablation, the VT burden was reduced from median of 4, inter-quartile range (IQR, 1-9) to 0, IQR (0-2). CONCLUSION: In this first-in-human multi-centre experience, endocardial ULTC ablation of monomorphic VT appears safe and effective in patients with both ischaemic-cardiomyopathy and non-ischaemic-cardiomyopathy. CLINICAL TRIAL REGISTRATION: NCT04893317.
- MeSH
- jizva komplikace MeSH
- kardiomyopatie * komplikace diagnóza chirurgie MeSH
- katetrizační ablace * škodlivé účinky MeSH
- komorová tachykardie * diagnóza etiologie chirurgie MeSH
- kryochirurgie * škodlivé účinky MeSH
- lidé středního věku MeSH
- lidé MeSH
- prospektivní studie MeSH
- senioři MeSH
- teplota MeSH
- výsledek terapie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- senioři MeSH
- Publikační typ
- časopisecké články MeSH
- klinické zkoušky MeSH
- multicentrická studie MeSH
