Strong Reaction Research Articles

Inhibition of cytosine 5-hydroxymethylation during progression of cancer precursor lesions in the uterine cervix.

Methylation and hydroxymethylation of cytosine moieties in CpG islands of specific genes are epigenetic processes shown to be involved in the development of cervical (pre)neoplastic lesions. We studied global (hydroxy)methylation during the subsequent steps in the carcinogenic process of the uterine cervix by using immunohistochemical protocols for the detection of 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) in paraffin-embedded tissues of the normal epithelia and (pre)malignant lesions. This approach allowed obtaining spatially resolved information of (epi)genetic alterations for individual cell populations in morphologically heterogeneous tissue samples. The normal ectocervical squamous epithelium showed a high degree of heterogeneity for both modifications, with a major positivity for 5-mC in the basal and parabasal layers in the ectocervical region, while 5-hmC immunostaining was even more restricted to the cells in the basal layer. Immature squamous metaplasia, characterized by expression of SOX17, surprisingly showed a decrease of 5-hmC in the basal compartments and an increase in the more superficial layers of the epithelium. The normal endocervical glandular epithelium showed a strong immunostaining reactivity for both modifications. At the squamocolumnar junctions, a specific 5-hmC pattern was observed in the squamous epithelium, resembling that of metaplasia, with the typical weak to negative reaction for 5-hmC in the basal cell compartment. The reserve cells underlying the glandular epithelium were also largely negative for 5-hmC but showed immunostaining for 5-mC. While the overall methylation status remained relatively constant, about 20% of the high-grade squamous lesions showed a very low immunostaining reactivity for 5-hmC. The (pre)malignant glandular lesions, including adenocarcinoma in situ (AIS) and adenocarcinoma showed a progressive decrease of hydroxymethylation with advancement of the lesion, resulting in cases with regions that were negative for 5-hmC immunostaining. These data indicate that inhibition of demethylation, which normally follows cytosine hydroxymethylation, is an important epigenetic switch in the development of cervical cancer.

A detailed high-pressure oxidation study of n-pentanal

Oxidation of n-pentanal is studied in a jet-stirred reactor at 10 atm for four dilute mixtures with equivalence ratios 0.3, 0.5, 1 and 2 and between 500–1150 K. A detailed kinetic sub-mechanism is developed and used along with the mechanisms representing the oxidation of two branched isomers of pentanal, namely 2- and 3-methylbutanal. At all conditions, n-pentanal showed a strong low-temperature reactivity and an NTC region. Among the experimentally observed species, ones related to the low-temperature oxidation of n-butyl radicals can be found, consolidating the importance of the (N-1) alkyl radicals in aldehyde chemistry. The kinetic mechanism showed good agreement against the data as well as other speciation data at atmospheric pressure from literature. The present data are also compared to previous similar studies on the oxidation of C3–C5 aldehydes in the same JSR and where n-pentanal shows the highest global reactivity.

Surface-gas chemistry coupling and stability limits of hydrogen/air combustion in catalytic microchannels

The catalytic (heterogeneous) and coupled catalytic-gaseous (hetero-/homogeneous) combustion of fuel-lean hydrogen/air mixtures (equivalence ratio φ = 0.4) in palladium- and rhodium-coated catalytic microchannels was numerically investigated in planar microchannels having a canonical geometry of 10 mm length and 1 mm height. Steady, extinction-induced combustion stability limits were demarcated as a function of inlet velocity and external heat loss at pressures of 1 and 5 bar, with wall thermal conductivities of 1 and 16 W/mK. In each case, interplays between the catalytic and gas-phase chemical reaction pathways, and their impact on the stability limits were identified. The stability results were further compared with literature data for platinum. The simulations indicated that Pd was more resilient against extinction than Rh and had a stronger surface reactivity when competing with gas-phase chemistry in the channel. Similar to Pt, the strong H2 surface reactivity on Pd resulted in wide stability limits purely determined by surface reactions and independent of gas-phase chemistry. In stark contrast, the presence of gas-phase combustion significantly expanded the stability limits of the Rh channel. The stability limits of Rh at 5 bar were consistently broader than those at 1 bar under all investigated conditions, which was also a behavior different to that of Pd and Pt channels, whose stability limit curves had crossover points between the two pressures. Additional simulations were performed in a Surface Perfectly Stirred Reactor (SPSR), providing comprehensive chemistry information, including sensitivity analyses of key reactions and surface coverages. When approaching extinction, OH(s) was a major surface species on Pd, while the Rh surface was primarily blocked by O(s).

Evolution and process analysis of the hearth activity in hydrogen-rich blast furnace

Blast furnace (BF) hydrogen-rich smelting is an important way for the green and low-carbon development of iron and steel industry. The injection volume of hydrogen-rich gas is limited due to the need for hearth activity, which is related to the stable and smooth operation of BF. In this study, the change of coke properties after hydrogen-rich smelting was summarized, the detailed evolution process of hearth activity after hydrogen-rich smelting was analyzed. The results show that: the pores on the surface of coke are enlarged after hydrogen-rich smelting. The gasification rate of coke with H2O is significantly higher than that of CO2 due to the lower activation energy and smaller molecular diameters of H2O and H2. The interlayer spacing of coke decreases and the stacking height further increases rapidly, the degree of coke graphitization is the highest after hydrogen-rich smelting. The weakening of carbon anisotropy is the fundamental reason for the increase in the degree of graphitization of coke. The strong gasification reaction causes the coke to lose a lot of carbon, and its matrix becomes loose and incomplete, so the strength after reaction decreases sharply. The wetting model is established to analyze changes in wettability. The rough surface of coke improves the wettability between slag iron and coke at high temperature. The good wettability makes it easier for slag iron to adhere to the surface of coke. The smoothness of slag iron passing through coke is reduced, the retention amount of liquid slag iron in coke layer increases. It leads to a decrease in hearth activity, the stable and smooth operation of BF is difficult to guarantee. This is the main issue limiting the injection volume of hydrogen-rich gas in BF.

Psychology and education in the 21st century: Analysis of the Russian teachers’ beliefs regarding the use of modern psychological knowledge in practice

The article proposes an approach to assessing the psychological knowledge of teachers through the analysis of their beliefs regarding the evidence-based principles formulated in the sciences of education in recent years. The study was conducted in 2021/2022 on a sample of Russian school teachers (N = 344, 93.3 % women, 41.7 % from Moscow). The authors’ questionnaire for the study of school teachers’ beliefs was used, based on the 20 evidence-based psychological principles important for teaching and learning, assessing the possession of principles in six areas: the role of the teacher in the effectiveness of learning; lack of faith in myths about teaching and learning; psychologically safe environment; student motivation; classroom management; assessment. The level of teachers’ conviction in the truth of evidence-based psychological principles ranges from 27.9 to 87.9%, while the higher the teacher’s experience, the less likely he believes in such principles and the more often he relies on unsubstantiated statements about teaching and learning. The highest levels of possession of evidence-based psychological knowledge by teachers are demonstrated in blocks related to student assessment and the creation of a psychologically safe environment compared to blocks describing the principles of classroom management, student motivation and the role of the teacher in learning effectiveness. It is also shown that teachers consider psychological knowledge necessary rather in non-standard, difficult practice situations (children with low educational motivation, low level of educational skills, conflicts, strong emotional reactions of students) than in standard situations (preparing and conducting lessons, interacting with students and their parents). The study showed the need for further development of such an approach to the study of psychological knowledge of teachers, which would be based on an assessment of their beliefs in the use of evidence-based psychological principles to resolve specific situations of school practice. The data obtained indicate the need to improve the psychological competence of teachers in general.

Self-compassion, Job-related Wellbeing, Perceived Stress, Happiness and Depression, and Anxiety Symptoms in 6 Cases of Senior Managers of Human Resources or Organizational Development

Introduction: Recent studies suggest that compassion, particularly self-compassion, is often perceived as contrary to effective leadership and organizational success, that self-compassion, which impacts emotion regulation through the acceptance of negative emotions, may be an adaptive strategy for managing stress and benefit for resilience at work, and that self-compassion is associated with happiness and inversely related to anxiety and depression. This can be taken together with the importance of job-related affective well-being, where low LPLA (Low Pleasurable Low Arousal emotions) and high LPHA (Low Pleasurable High Arousal emotions) can correlate to depression, anxiety, and stress. The following self-report questionnaires were used: the Self-Compassion Scale (SCS-SF), the Job-Related Affective Well-Being scale (JAWS), the Perceived Stress Scale (PSS 10), the Subjective Happiness Scale (SHS), the Depression Anxiety Stress Scale (DASS-10). The aims of this case series are to assess these components in six senior managers of human resources or organizational development, to understand their interconnections, and to compare the results with previous studies. Results and discussion: The six cases’ configurations of scores (age 46-67, 4 female, 2 male) for self-compassion, job-related wellbeing, perceived stress, happiness, depression/anxiety symptoms, vary widely. Five out of six cases in this case study have higher levels of perceived stress than the norms established by previous research. The youngest among the cases is case 5 and exhibits the highest stress levels, the highest depression/anxiety levels, and a high self-compassion level simultaneously. One case has severe depression/anxiety levels, and two cases have moderate levels of depression/anxiety. Four out of six cases have high levels of self-compassion. All six cases exhibit strong negative emotional reactions to their job and level of overall job-related affective well-being is low. The six cases in this study show the same trends outlined in the previous research: (1) self-compassion is associated with happiness and (2) self-compassion is inversely related to anxiety and depression, (3) anxiety and depression are inversely related to happiness,(4) perceived stress is negatively correlated with self-compassion (in turn that self-compassion could protect against stress, and (5) low LPLA and high LPHA levels corelate to depression, anxiety, and stress. Conclusion: Timely awareness among managers of their levels of self-compassion, job-related well-being, perceived stress, and symptoms of depression and anxiety can be valuable in preventing the escalation of stress and the deterioration of mental health. By recognizing and addressing these factors early, managers may mitigate negative emotional outcomes, thereby fostering a healthier work environment and improving overall job satisfaction and performance.

Trust in a Digital World. The Roles of Media Trust and Ordinary Citizen Cues in Online Disinformation’s Credibility

The perception of disinformation as societal risk has reached a troubling peak amid the COVID-19 pandemic, strategically targeting vulnerable audiences through digital media by mirroring characteristics of vox populi disinformation. This study investigates the conditions under which COVID-19-related disinformation referring to a polarized (refugees) and neutral (runners) out-group appears most credible. In the early stages of the pandemic, we conducted a pre-registered online survey experiment with a representative German sample (N = 1,117). Results indicated that those with low trust in the media judged subtle and completely fabricated types of disinformation as more credible than accurate information. Presenting the article as a social media post from an ordinary user, rather than an official source, had no discernible impact on credibility evaluations; participants accurately assessed the credibility of a random source. We conclude that people are generally able to recognize disinformation—unless they already mistrust the media. This paper addresses why disinformation triggers strong reactions in targeted groups and how it thrives in the participatory digital landscape.

Serum levels of cortisol, adrenaline, noradrenaline, glucose and platelet counts in cats depending on the behavioural assessment of acute stress

The aim of this study was to combine the estimated intensity of acute stress experienced by cats in the veterinary clinic with the assessment of serum cortisol, adrenaline, noradrenaline, glucose and platelet counts. The authors aimed to answer the question of whether the generally known acute stress markers correlate with the degree of stress experienced by cats in the veterinary clinic. Fifty clinically healthy cats were studied. Behavioural assessment of stress was performed according to the modified criteria indicated by Kessler and Turner under conditions of minimal stress recommended for veterinary medicine. Serum levels of cortisol, adrenaline, noradrenaline, glucose and platelet count were determined by recognized and commonly used methods. The cats examined in the clinic were divided into 3 groups according tothe type of stress reaction. In 8 (16%) cats, the behaviour was “relaxed”, 25 (50%) cats showed “tense” stress reactions, and in 17 (34%) cats, strong reactions of fear were noted. Serum levels of cortisol, adrenaline, noradrenaline, glucose and platelet count differed between the groups, but the differences were not statistically significant and did not correlate with the degree of acute stress in cats. It is concluded that a large number of cats (84%) experience stress in the clinic and that the working methods of veterinary teams should be further improved to minimize it. When cats exhibit less fear during veterinary examinations, their owners are more likely to schedule examinations, and veterinarians are more likely to obtain accurate measures during the examination, which improves the overall welfare of the cat. Another conclusion is that the biochemical parameters tested did not meet the conditions to be treated as measures of acute stress in cats. Therefore, further research is needed to find indicators associated with the degree of acute stress in cats.

Isolation and culture of chickenembryonic synovial fibroblasts.

Cells obtained from chicken embryos are often preferred for in vitro studies. These cells, which easily adapt to rapid and continuous growth in the appropriate cell culture environment, are thought to be one of the effective methods in the investigation of leg diseases that are frequently observed in poultry. Leg diseases, especially affecting the joints in chickens, cause locomotor problems and adversely affect animal welfare. In addition, they cause significant health problems and increase mortality. It is known that synovial fibroblasts play an important role in joint diseases. In this study, chicken embryonic synovial fibroblasts were isolated from tissue explants taken from the tibio-metatarsal joint region of brown layer chicken embryos. Characterization of cells was evaluated by immunocytochemistry and hemacolor staining. chicken embryonic synovial fibroblasts showed a strong positive reaction to the vimentin antibody. As a result of hemacolor staining, it was noted that the cell morphology was spindle-shaped. The absence of macrophages in chicken embryonic synovial fibroblast culture was confirmed by the carbon powder uptake. In this present study, we aim to present a useful cell culture protocol such as primary culture, passage, and characterization suitable for chicken embryonic synovial fibroblast to be used in the new scientific research.

A new indole alkaloid and anti-malarial activity of the stem bark extract of Chrysophyllum albidum

Background to the study: Chrysophyllum albidum stem bark extract had been shown to be antimalarial active in various studies but the compound responsible have not been identified. Methods: Its stem bark ethanol extract was successively partitioned to obtain n-hexane, ethyl acetate, butanol fractions and the aqueous phase with the aim of isolating the antimalarial constituent(s). The fractions were all tested for chemosuppressive activities at doses 0-80 mg/kg using Peter’s four-day test in Plasmodium berghei berghei-infected mouse model with chloroquine (10 mg/kg) and normal saline as positive and negative control respectively Result: The partitioned fractions: n hexane, butanol and aqueous with ED50 44.71±4.88, 54.84±4.25 and 54.42±3.84 and 56.6±4.64 respectively were comparable (p>0.05) in activity to each other. The ethyl acetate fraction with strong reactions to Dragendorff’s reagent and similarly has good weight, was further purified by repeated column chromatography leading to the isolation of a new indole alkaloid identified and characterized as 4, 5, 7, 8-tetrahydro-1H-1, 4-epoxyazepino [1′, 2′: 1, 2] pyrido [3, 4-b] indole-2, 3, 3(2H, 13H, 13bH)-triol (1) named as albidumine with a molecular formula C16H18N2O4. In addition, eleaginine (2), previously characterised from the seed was also identified in this stem-bark through LC-MS. To the best of our knowledge, compound 1 is a new alkaloidal constituent in Chrysophyllum sp. The structure was elucidated using the data from mass spectra, 1D (1H, 13C NMR and DEPT) and 2D-NMR (HMQC and HMBC) spectra. Conclusion: A new indole alkaloid isolated from ethyl acetate fraction of the ethanol extract of the stem-bark of Chrysophyllum albidum and characterised as albidumine may likely be an antimalarial constituent of the plant

Development of green cement from solid wastes

In this study, a green cement (GC) was prepared primarily using incineration bottom ash (IBA) and recycled concrete fine (RCF) at a low clinkering temperature of 1200ºC. This clinker mainly consisted of belite (C2S) and rankinite (C3S2) and demonstrated the versatility of strong carbonation reactivity and latent hydraulicity. Compared to the commercial benchmark - ordinary Portland cement - after being subjected to carbonation curing, GC exhibited superior macro- and micro-mechanical performance due to the densified microstructure. In addition to rapid strength gain at an early age, the carbonated GC also exhibited a substantial increase in strength at later ages and eventually recorded a high strength of 86.4 MPa. Furthermore, the leaching behaviour assessment on commonly regulated heavy metals validated the environmental stability of this waste-derived binder. The development of this sustainable cement has good potential to divert solid wastes otherwise destined for landfill sites to high-value-added construction products.

Unfavorable process intensification of double column reactive extractive distillation system

This study evaluated the energy saving potential of process intensified double column reactive extractive distillation (DC-RED) through three case studies. The results showed that process intensified technologies, thermally coupled reactive extractive distillation (TC-RED) and dividing wall reactive extractive distillation (DW-RED), did not yield any energy savings compared to conventional DC-RED. Contrary to the expectation, the elimination of the remixing effect in the process intensified DC-RED did not lead to any energy savings. Further analysis revealed that the remixing effect was not significant enough to achieve energy savings through process intensification, and the strong reaction exotherm in DC-RED reduced the potential for energy saving. Additionally, the higher interconnection flowrate in TC-RED and DW-RED resulted in higher energy consumption due to the increased boil-up ratio. Moreover, the lower feed temperature to the solvent recovery column (SRC) led to less energy efficiency and larger reboiler duty. An alternative energy saving scheme was proposed by adding a heat exchanger (HEX). The addition of HEX led to energy savings of 37.23 % in Acetonitrile (ACN)/Isopropanol (IPA)/Water separation, 45.62 % in Ethyl Acetate (EA)/Ethanol (EtOH)/Water separation, and 39.21 % in IPA/EA/Water separation.

The revenge of ‘democratic peace’

The Russo-Ukrainian war may have given democratic peace a new lease of (research) life. The stronger-than-expected reaction of liberal democracies coupled with the poorer-than-expected battlefield performance of the Russian military, invites us to re-apply the logic of democratic peace. To understand the strong reactions of liberal democracies, I apply a militant interpretation of Kant’s perpetual peace and reexamine the role of trade interdependence in capitalist peace. To understand the battlefield performance of Ukraine, I examine theories of war-fighting with an emphasis on the legitimacy mechanism. To understand the battlefield performance of Russia, I examine the deleterious impact of corruption and preference falsification ( vranyo). To the extent that the field is still generating novel research that advances our understanding of the impact of regime type on international conflict, democratic peace remains a progressive research programme.

Self-regulation of bed temperature field of the fixed-bed reactor unit by composite-filled oxygen carriers for chemical looping combustion of methane

Fixed-bed reactors (FBRs) are suitable for chemical looping combustion (CLC) of gaseous fuels. However, the non-uniform temperature field such as the formation of hotpots can easily lead to the deactivation of oxygen carriers (OCs), ultimately leading to the degradation of the CLC performance and the durability of the OCs. This work systematically investigates the effect of individual CuO/SiO2 and Fe2O3/Al2O3 OC-filled FBR units on the bed temperature field using a self-built experimental setup to monitor the real-time bed temperature evolution. In addition, a strategy for self-regulating the bed temperature field by composite OCs-filled FBR units is proposed based on the differences in the thermodynamic properties of different OCs, including CuO/SiO2, Fe2O3/Al2O3, Mn2O3/ZrO2 and NiO/ZrO2. It has been found that the radial bed temperature of a single CuO/SiO2 OC-filled FBR unit is significantly higher than that at the central axis, and the bed temperature fluctuates within a range of ± 50 °C throughout the CLC process. The bed temperature of a single Fe2O3/Al2O3 OC-filled FBR unit fluctuated within a range of ± 25 °C during the reduction stage, but the bed temperature increased by nearly 100 °C due to the strong exothermic reaction of the oxidative regeneration of the reduced Fe2O3/Al2O3 OCs. The use of composite OCs-filled FBR units not only improves the CH4 conversion and CO2 selectivity, but also maintains a stable bed temperature fluctuates within a range of ± 15 ℃ during the different reaction stages of the CLC process. The synergistic effect between the OCs contributes to the bed temperature field remaining in a relatively stable state. The results indicate that the rational distribution of composite-filled OCs in FBRs can achieve self-regulation of the bed temperature field to some extent by exploiting the OCs’ endothermic and exothermic properties.

Corrosion behavior of 304 stainless steel in supercritical water

Supercritical water (SCW) has strong reactivity and the ability to fuse non-polar substances, but it requires higher corrosion resistance of structural materials. To select reliable candidate materials for a supercritical water system, this study investigated the corrosion behavior of 304 stainless steel (304 SS) in supercritical water (798 K/24 MPa). After soaking 304 SS in supercritical water for 200 h, the oxidation kinetics, surface morphology, and element diffusion were studied by weight measurement, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The surface of 304 SS shows an isolated and discontinuous oxidation deposition. It is determined that the oxide layer is a single layer, mainly composed of Fe-Cr-rich spinel, with a small amount of magnetite attached to the surface of the oxide layer. Besides, the oxidation mechanism was also studied since some pores were found on the surface due to pitting.

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Experimental evaluation of the effect of sulfur content on the spontaneous combustion characteristics parameters of coal

The coal spontaneous combustion (CSC) is the main hazard threatening the coal safety production. In this work, the CSC characteristic, CSC tendency and limit parameters with different sulfur were measured and discussed using temperature-programmed experiment. The results show that the cross-point temperature (CPT) decreases first and then increases with the increasing sulfur content. The CSC tendency of coal with sulfur content in the range of 3.28–5.13 % is greater than that with sulfur content of 2.57 % and 7.59 %. When sulfur content is less than 5.13 %, sulfur and its unstable compounds in coal have strong reactivity and can promote oxidation reaction. When sulfur content is greater than 5.13 %, a large number of sulfur-containing substances reduce the contact area of coal oxygen molecules, which inhibits the oxidation reaction of coal. The sulfur content of coal sample has a significant effect on the limit parameters of coal spontaneous combustion.

Electro-Structured Cu Distorted Nanopyramids for Superior Sweat Glucose Sensing

There is a rising global demand for non-invasive glucose monitoring devices, due to an increase in diabetes and its associated health problems. Nanostructures, including needles, fibers, and rods, have drawn considerable attention due to their unique structural-based physical and chemical features in non-enzymatic electrochemical sensing. Copper is a potential candidate for applied research because of its higher electrical conductivity, low cost, and strong reactivity. To create 3-D nano copper structures, researchers have investigated chemical, electrochemical, and hydrothermal techniques. The electrochemical method can better control the formation reaction for these structures. The electrochemical process has better control over the formation reaction for these structures.Distinctive and self-supported copper nanopyramids were electrochemically created on a copper substrate within a few seconds by electrochemical deposition in a one pot synthesis. The SEM image of the constructed nano copper pyramids are shown in figure 1a. The built nano pyramids have a length of ~200 nm. The generated nanostructures display excellent catalytic activity for non-enzymatic glucose sensing. The created nonenzymatic sensor was tested for glucose detection in synthetic sweat and it displayed a linear response in the range of 20 µM- 2000 µM, making it appropriate for practical applications. The chrono amperometry for glucose sensing was performed at 0.5V for 60s. Figure 1b shows the calibration plot for glucose sensing. Linear response for the glucose was observed in the range from 20µM – 2000µM. The device showed a very low interference for uric acid and ascorbic acid. The device is stable upto 60 days, highly reproducible and can be reused upto 5 times. The correlation coefficient was 0.9857 for the linear equation I(μA) = (9.52*10-3) *C (in µM) + 5.065 and a sensitivity of 1.17 nA/(μM-cm2) was observed Figure 1

Growth Mechanism and Film Properties of Atomic-Layer-Deposited Titanium Oxysulfide

Titaniumoxysulfide (TiOxSy) is a technologically-relevant material for batteries, catalysis and, the area of our focus: photovoltaics. One of the key merits of TiOxSy is the wide range of electrical conductivity and optical absorption that can be achieved by tuning its composition. In this contribution, we present a supercycle-based ALD approach for TiOxSy which combines ALD of amorphous TiO2 and semimetallic two-dimensional (2D) TiS2, and uses tetrakis(dimethylamido)titanium (TDMATi), H2O and H2S as precursors. While ALD with supercycles is generally acknowledged to give a high level of control over film composition, in this case of TiOxSy we show through a variety of in-situ techniques that many effects occur during the ALD supercycles that strongly affect the film growth and resulting film properties. Yet, by understanding and taking these effects into account, the supercycle process allows for accurate tailoring between pure TiOx and TiSx. The effects of study focus mainly on exchange reactions and the film crystal morphology and its effect on the growth rate. Exchange reactions: QMS measurements show that during supercycle ALD, strong exchange reactions occur during the H2O dosing step, where exchange occurs between underlying TiSx and H2O, resulting in the formation of TiOx and release of H2S. The exchange reactions and their effect on the film growth were studied in-depth using in-situ SE. From these studies, it was found that during ALD TiO2 cycles on TiSx, the exchange reactions behave similarly at 100 and 150 °C, while being more pronounced at 200 °C. Specifically, at 100 and 150 °C, the reactions persist for about seven cycles and stop once approximately 3−4 Å of TiO2 has grown, while at 200 °C, the reactions are more prominent and persist for about nine cycles and stop once approximately 5 Å of TiO2 has grown. This TiO2 forms both through back-oxidation of underlying TiSx and by ALD of TiO2 on top. These exchange effects are thus less prominent at lower growth temperatures, facilitating more accurate control over composition. Film crystallinity: Interestingly, the pure ALD TiO2 and TiS2 processes yield films of very different morphology. Whereas ALD TiO2 at these temperatures results in smooth, amorphous films that grow with a constant growth-per-cycle (GPC), in the case of pure ALD 2D-TiSx the growth process is more intricate: Electron microscopy shows that these 2D films initially have crystal growth that occurs laterally, up to the point of coalescence where the 2D layers start to grow out of plane. As ALD growth on the sideplanes of the 2D material is much faster, the GPC of these films keeps increasing as the film thickness progresses. When combining ALD TiO2 and TiS2 in a supercycle, the TiO2 cycles interrupt the growth of the 2D TiS2 crystals. This not only leads to a lower crystallinity of the film, but due to suppression of the reactive 2D-TiS2 edges, also the GPC is strongly reduced. As such, this effect has a strong influence on the resulting film thickness and composition, which is markedly different than would be expected than on the basis of the constituent ALD cycles in the supercycle.Based on the insights, we present a model that can explain the relation between supercycle ratio, deposition temperature and the resulting film properties. This enables the control over film conductivity over six orders of magnitude, where Hall measurements show that S-rich films exhibit both higher carrier densities and carrier mobility. Similary, controlling the composition allows tuning the optical properties between opaque, semimetallic 2D-TiS2 and transparent, dielectric TiO2 with a bandgap a little over 3 eV.Since exchange reactions and film crystallinity are common factors in ALD films, we expect these results to be of broader interest to the ALD community, for those preparing multicomponent materials using supercycles Figure 1

Optimization of two-stage thermal desorption combined with pentafluorophenyl hydrazine derivatization-gas chromatography/mass spectrometry analytical method of atmospheric carbonyl compounds

The detection method of carbonyl compounds (CCs) in the atmosphere has been a challenging problem because of its low concentration and strong volatility and reactivity. Based on the existing thermal desorption (TD) technology, the TD instrument was combined with gas chromatography/mass spectrometry (GC/MS), and pentafluorophenyl hydrazine (PFPH) was used as derivatization reagent to establish a simple, high sensitivity, good stability and simultaneous detection of 13 atmospheric carbonyl compounds, namely PFPH derivation-two-stage TD-GC/MS analysis method. The main factors affecting the TD conditions were discussed, including desorption temperature, desorption time and carrier gas flow rate. The results showed that when the tube desorption flow rate and time were 10 mL min−1 and 8 min, and the trap desorption flow rate and time were 5 mL min−1 and 8 min, the recoveries of various CCs PFPH-derivatives were relatively high. The collection efficiencies of all detected carbonyls by this method were above 85 %. The method detection limits (MDLs) of the tested carbonyls were in the range of 0.44–1.23 ng cartridge−1. Compared with the method of PFPH-solvent desorption-GC/MS, the two-stage TD-GC/MS method showed lower MDLs and more carbonyls detected at low concentrations. In brief, the two stage TD-GC/MS analysis method is of great significance for the detection of trace CCs in the time-varying atmospheric environment, and is worthy of popularization and application in atmospheric samples.