Abstract
This research reports a micro-fabrication method for plastic microscale structures. Although a stepped shape, such as a cantilever, can be fabricated by micro electro mechanical systems ...(MEMS) deep etching technology, its disadvantages include the complicated fabrication process and its limited utilization with silicon only. Therefore, in this study, with an aim to address the aforementioned problems, we have realized the fabrication of a multi-stage structure using just a general photolithography process with high versatility. Specifically, it can be manufactured using only SU-8 resist and AZ resist, which are often used in the MEMS process. The AZ resist has the advantage of dissolving in the developer of the SU-8 resist, whether exposed or non-exposed. Thus, the sacrificial layer of AZ resist can be implemented with the SU-8 developer, thereby eliminating the need for dangerous chemicals such as hydrofluoric acid, which is used to etch silicon oxide. Herein, we have derived the optimum conditions by considering in advance the thickness of the AZ resist, the time taken to be etched in SU-8, and the desired features. Based on these optimum processing conditions, the structure could be suspended only in the region where the hole array was patterned. Although methods of using AZ resist as a sacrificial layer and floating SU-8 have been reported, in this study, both floating and fixed structures could be simultaneously fabricated by photolithography only. Accordingly, we successfully manufactured a gear structure and a MEMS sensor, both of which have floating and fixed structures. The above structures are made of highly transparent SU-8 on a glass substrate; hence, they are easily observable with a microscope. The reason for the widespread use of polydimethylsiloxane micro-channels is that they are transparent materials that can be observed under a microscope and fabricated by simple photolithography of the SU-8 resist, enabling non-microfabrication specialists to enter this field. These findings have the potential to form the foundation for developing new biochemical tests, such as actuators and sensors driven under a microscope.
Abstract
We report NMR experiments on heavily electron-doped Fe-based superconductor in comparison with the results on the parent Fe-based compounds. The typical parent Fe-based compound LaFe(As
1-
x
...′
P
x
′
)O exhibits the re-emergent antiferromagnetic (AFM) order at
x
′ ~ 0.6 (AFM2) separated from the parent AFM order at
x
′ =0 (AFM1). Systematic
31
P-NMR study on Sr
4
Sc
2
O
6
Fe
2
(As
1−
x
P
x
)
2
(SrSc42622), which has local lattice parameters of iron-pnictogen (Fe
Pn
) layer similar to the series of LaFe(As
1−
x
′
/P
x
′
)O, also revealed that the presence of AFM1 order is universal for most of parent Fe-based compounds. In contrast, the static AFM2 order was absent in this series, however, the dynamical low-energy AFM spin fluctuations are enhanced at around
x
~ 0.8, indicating that the onset of the static AFM2 is quite sensitive to the local lattice parameters of Fe
Pn
layer. In order to elucidate the further universality and diversity, we have carried out
77
Se-NMR measurement on Li
x
(NH
3
)
y
Fe
2−
δ
Se
2
(
T
c
= 44 K) in heavily electron-doped regime. Although the spin fluctuations at low energies does not significantly develops upon cooling, the moderate spin fluctuations were extracted at high temperatures from comparison of the temperature (
T
) dependences of Knight shift and nuclear relaxation rate (1/
T
1
T
). We discuss the universality and diversity of the relationship between the
T
c
and the characteristics of the spin fluctuations in the Fe-based compounds from a microscopic point of the NMR measurements.
We report 75As NMR experiments in heavily electron-doped LaFePnO0.75H0.25 (Pn=As1−xSbx and As1−x′Px′) compounds with the maximum Tcmax(∼33.1K), and compare with the previous results in lightly ...electron-doped LaFePn(O,F) compounds. The Tc of this series can be sensitively controlled by the pnictogen height (hPn) through the substitution at Pn site, and the electron doping level through the substitution at the O site with H or F. In heavily electron-doped LaFePnO(La1111) compounds, we found that spin fluctuations at low-energies were moderately suppressed upon cooling in the Sb-substituted high Tc compounds with high hPn (x ≥ 0), although they are completely suppressed in P-substituted non-superconducting compounds (x′ ≥ 0.2) with lower hPn. This feature is largely different from that in the lightly doped La1111 compounds with the well-nested Fermi surfaces, where the spin fluctuations are critically enhanced upon cooling. Here, we present the characteristics of spin fluctuations over wide doping region of La1111-based compounds, and discuss the relationship with the superconductivity.
This comparative investigation aimed to evaluate controlling factors for the changes of chemical and microbial properties in soils taken from chemical fertilizer experiments carried out mainly in ...Chernozem and Andosol in Hungary and Japan, respectively. The plant available nutrient content of the soil, the stock of C and N and the soil microbial parameters of the carbon and nitrogen cycles were examined under different land-use and vegetation. In the Japanese soils, there was about 2-3 times higher organic C content than in Hungarian soils. The average CO
2
-production was about 1.5 times higher in Hungary soils than Japanese soils, and significantly increased (9-37%) in the fertilized treatments compared to control in all Hungarian long-term experiments. Regarding the Hungarian soils, the NPK-fertilization especially increased the nitrate and phosphorus content of soils, among the microbial parameters of the CO
2
-production, MBC, MBN, net nitrification, saccharase and urease activities - in most cases significantly increased - among the six microbial examined parameters. With reference to Japanese soils, the nitrogen fertilization especially increased the nitrate and phosphorus content of soils and had the highest effect on the microbiological parameters in the forest soil, where the MBC, MBN, net nitrification, saccharase and urease activities increased significantly. Only the net nitrification increased significantly in the fertilized treatments in the all Numata experiments, and generally 10-100 times higher values were found in the Japanese soils than in the Hungarian ones. The microbial activity decreased according to land use in the following order: maize>forest>grassland in Hungary soils, and forest>grassland>apple orchards in Japanese soils. These results confirm that climate conditions and human activity have important impacts on the C and N cycles of the soil-plant-atmosphere system. Based on our results, it appears that land-use and chemical fertilization resulted in a larger change in the stock of organic matter and soil microbiological processes in the Hungarian long-term experiments compared to the Japanese experiments.
Pure zirconium oxide nanocrystallites with diameters 6–140
nm are fabricated from ultrafine metallo-organic complexes by thermal hydrolysis at 120
°C and/or heat treatment at 125–1025
°C. X-ray ...photoelectron spectroscopy shows that effective ionic valence of Zr decreases with decreasing particle diameter. The size dependence of the ionic valences suggests that the phase transition from cubic to tetragonal occurs at an effective Zr valence of 2.0 near 3
nm in diameter and that the phase transition from tetragonal to monoclinic takes place at a critical size of 25
nm diameter with an effective Zr valence of about 2.6.
Structural science of new ionic conductors Fujii, K.; Yashima, M.
Acta crystallographica. Section A, Foundations and advances,
08/2023, Letnik:
79, Številka:
a2
Journal Article
Methane is one of the greenhouse gases emitted from paddy soil ecosystems and may induce global warming and climate change; therefore, mitigation options are urgently required to establish mitigation ...technology to reduce methane emission without affecting rice production. Methane is produced by a balance between oxidizing agents (such as iron) and reducing agents (easily decomposable soil organic matter), according to the so-called Takai theory. To evaluate options for mitigating methane production potential and to examine the applicability of the Takai theory in Southeast Asian paddy soils, 23 soil samples were collected from Thailand, Indonesia, Philippines, and Vietnam. These soil samples were anaerobically incubated to measure their methane production potential and examined to see whether their chemical properties, such as the ferrous, total iron, and organic matter contents, were correlated. We found a significant negative correlation between the methane production potential and the total iron content, and a positive correlation between the methane production potential and the hexose content, as an index for a soil's easily decomposable organic matter content. The methane-C/CO
2
-C production ratio was also positively correlated with the mineralizable nitrogen/ferrous contents ratio, which indicated that the Takai theory, established for Japanese paddy soils, is also useful in Southeast Asian paddy soils and that the soil's iron content is important to estimate the methane production potential.
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