A series of nanocrystalline Ni
1−
x
Mn
x
Ce
x
Fe
2−
x
O
4
(
x
= 0.0, 0.02, 0.04, 0.06, 0.08, and 0.1) were prepared using the citrate auto-combustion method. X-ray diffraction (XRD) indicates that ...the spinel materials formed in a cubic single phase up to the sample
x
= 0.02. The average crystallite size is reduced from 61 to 31 nm due to the suppression of grain growth upon cerium occupation at the octahedral site. The cubic spinel structure was confirmed by Fourier-transform infrared (FT-IR) analysis. Scanning electron microscope (SEM) showed agglomerated and rod-shaped structures at various concentrations. AC conductivity and dielectric properties were measured over a frequency range of 20 Hz to 8 MHz. The AC conductivity increases with an enhancement in frequency. The prepared materials have great potential for utilization in microwave devices. The magnetic parameters were estimated from the measured hysteresis loops at room temperature and 100 K using a vibrating sample magnetometer (VSM), which indicated that the samples were suitable for magnetic memory device applications.
Mixed nickel-zinc-chromium ferrites having the general formula Ni0.7Zn0.3CrxRyFe2-x-yO4 (where x = 0.5, y = 0.02 and R = Gd3+, Sm3+ and Ce3+) were prepared, for the first time by using ...auto-combustion method at low sintering temperature (523 K). X-ray diffraction (XRD) analysis and Fourier transform infrared spectrum (FT-IR) confirmed the formation of single phase spinel structure in all the samples. The variations of the lattice parameter and particle size were discussed in the view of ionic radii. High resolution transition electron microscope (HT-TEM) and scan electron microscopy (SEM) images showed spherical and elongated shapes of the nanoparticles where the average particle size ranged 13–17 nm. The vibrating sample magnetometer (VSM) measurements confirmed a strong influence of rare earth doping on the saturation magnetization (Ms) and coercivity (Hc) due to the preferential occupation of RE ions in the octahedral B-sites. The magnetic parameters suggested that these nano-materials are suitable for technological application. The dielectric parameters (ε׳, ε″ and tanδ) and electrical conductivity (σ) were measured at different temperatures in the frequency range (102–105Hz). The electrical conductivity of the sample ferrite doped with Gd was showing semi-conducting behavior while for the samples doped with Ce and Sm, semi-conductor to semi-metallic were observed. The dielectric loss (tanδ) and dielectric constant (ɛ) show that these materials are useful in high frequency applications.
1Effect of rare earth elements on the properties of mixed nanoferrites.2The samples were prepared for the first time by using auto-combustion method.3X-ray diffraction analysis confirmed the formation of single phase spinel structure.4The results show that these materials are useful in high frequency applications.
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•Ferrite of composition Mg1−yCuyMn0.1InxFe1.9−xO4 with (0.0≤x≤0.4; y=0.0; 0.1) has been synthesized.•Electric, magnetic and Mössbauer studies have been investigated.•The real and ...imaginary parts of electric modulus follow the Arrhenius law.•Saturation magnetization increases up to x=0.2 and thereafter it decreases.•Good agreement between the magnetic and Mössbauer effect studies.
Ferrite of composition Mg(1−y)Cu(y)Mn(0.1)In(x)Fe(1.9−x)O4 with (0.0≤x≤0.4; y=0.0 and y=0.1) has been synthesized by solid state reaction technique. X-ray diffraction (XRD) patterns of the samples indicated the formation of single-phase cubic spinel structure up to 0.2 and mixed phase for samples x≥0.3. Vibrating sample magnetometer (VSM) measurements indicated that the saturation magnetization increases up to x=0.2 and thereafter it decreases. Electric modulus analysis was used as a tool to analyze the electrical behavior of the samples. The activation energies extracted from real M′ (ω) and imaginary M″ (ω) peaks were found to follow the Arrhenius law. The area ratio of Fe3+ at the tetrahedral A- and octahedral B-sites was deduced from the spectral analysis of Mössbauer measurements. The results give evidence that In3+ replaces Fe3+ at A-site in the range (0.0<x≤0.2). As the In3+ content increases; it replaces Fe at B-site.
Ferrite nanomaterials in the form of CoAg
x
Fe
2−
x
O
4
(
x
= 0.0, 0.03, 0.07, 0.1, and 0.2) have been prepared by the citrate autocombustion method. Structural analysis was carried out by x-ray ...diffraction. Fourier-transform infrared spectroscopy confirmed the formation of a spinel crystal structure. High-resolution transmission electron microscopy revealed the formation of particles with mixed morphologies. The average particle size ranged from 22 nm to 31 nm. Vibrating-sample magnetometry revealed that the saturation magnetization
M
s
and coercivity
H
c
were affected by the grain size variation. The electrical properties of the samples were investigated over the frequency range from 10
2
Hz to 10
5
Hz. Electric modulus analysis showed that the conduction was due to short-range mobility of charge carriers. The variation of the dielectric loss with frequency at different temperatures indicated two types of conduction mechanism. All these results suggest that the synthesized materials can be recommended for fabrication of exchange spring magnets and electrode materials.
The samples Ni
1+
x−
y
Zn
y
Ti
x
Fe
2−2
x
O
4;
y=0.1, 0.0≤
x≤0.5 were prepared in a single-phase spinel structure as indicated from X-ray analysis. Electrical conductivity and dielectric measurements ...at different temperatures from 300
K to 600
K in the frequency range from 42
Hz to 5
MHz have been analyzed. The relation of conductivity with temperature revealed a semiconductor to semimetallic behavior as Ti
4+ concentration increases. The conduction mechanism depends mainly on the valence exchange between the different metal ions in the same site or in different sites. The dielectric constant as a function of temperature and frequency showed that there is a strong dependence on the compositional parameter
x. The electrical modulus has been employed to study the relaxation dynamics of charge carriers. The result indicates the presence of correlation between motions of mobile ion charges. The activation energies extracted from
M′(
ω) and
M″(
ω) peaks are found to follow the Arrhenius law. The electrical conductance of the samples found to be dependent on the temperature and frequency.
The transcription factor p53 is a vital tumor suppressor. Upon activation by diverse stresses including oncogene activation, DNA damage, hypoxia and nutrient deprivation, p53 activates a panoply of ...target genes and orchestrates numerous downstream responses that suppress tumorigenesis. Although early studies of p53 suggested that its ability to induce cell cycle arrest, senescence and apoptosis programs accounted for its tumor-suppressor activity, more recent studies have challenged this notion. Moreover, p53 regulates a suite of additional processes, such as metabolism, stem cell function, invasion and metastasis. The processes p53 coordinately regulates to enact tumor suppression, and how such regulation occurs, thus remain elusive. In this review, we will summarize our current knowledge of p53-mediated tumor-suppressive mechanisms gleaned from in vivo studies in mouse models.
Deep Learning in Mining Biological Data Mahmud, Mufti; Kaiser, M. Shamim; McGinnity, T. Martin ...
Cognitive computation,
2021/1, Letnik:
13, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Recent technological advancements in data acquisition tools allowed life scientists to acquire multimodal data from different biological application domains. Categorized in three broad types (i.e. ...images, signals, and sequences), these data are huge in amount and complex in nature. Mining such enormous amount of data for pattern recognition is a big challenge and requires sophisticated data-intensive machine learning techniques. Artificial neural network-based learning systems are well known for their pattern recognition capabilities, and lately their deep architectures—known as deep learning (DL)—have been successfully applied to solve many complex pattern recognition problems. To investigate how DL—especially its different architectures—has contributed and been utilized in the mining of biological data pertaining to those three types, a meta-analysis has been performed and the resulting resources have been critically analysed. Focusing on the use of DL to analyse patterns in data from diverse biological domains, this work investigates different DL architectures’ applications to these data. This is followed by an exploration of available open access data sources pertaining to the three data types along with popular open-source DL tools applicable to these data. Also, comparative investigations of these tools from qualitative, quantitative, and benchmarking perspectives are provided. Finally, some open research challenges in using DL to mine biological data are outlined and a number of possible future perspectives are put forward.
•Motor skills are often impaired among ADHD children, the degrees of severity vary from light to severe impairment.•Motor deficit in fine and/or gross motor skills can be found.•More than half of the ...ADHD children improve motor skills under medication.•Different explanations of the motor skill deficits can be given: comorbidity, inattention or lack of inhibition.
This article presents a review of the studies that have analysed the motor skills of ADHD children without medication and the influence of medication on their motor skills. The following two questions guided the study: What is the evidence of impairment of motor skills and aspects of motor control among children with ADHD aged between 6 and 16 years? What are the effects of ADHD medication on motor skills and motor control? The following keywords were introduced in the main databases: attention disorder and/or ADHD, motor skills and/or handwriting, children, medication. Of the 45 articles retrieved, 30 described motor skills of children with ADHD and 15 articles analysed the influence of ADHD medication on motor skills and motor control. More than half of the children with ADHD have difficulties with gross and fine motor skills. The children with ADHD inattentive subtype seem to present more impairment of fine motor skills, slow reaction time, and online motor control during complex tasks. The proportion of children with ADHD who improved their motor skills to the normal range by using medication varied from 28% to 67% between studies. The children who still show motor deficit while on medication might meet the diagnostic criteria of developmental coordination disorder (DCD). It is important to assess motor skills among children with ADHD because of the risk of reduced participation in activities of daily living that require motor coordination and attention.
Objective
To validate a revision of the Mini Nutritional Assessment short-form (MNA®-SF) against the full MNA, a standard tool for nutritional evaluation.
Methods
A literature search identified ...studies that used the MNA for nutritional screening in geriatric patients. The contacted authors submitted original datasets that were merged into a single database. Various combinations of the questions on the current MNA-SF were tested using this database through combination analysis and ROC based derivation of classification thresholds.
Results
Twenty-seven datasets (n=6257 participants) were initially processed from which twelve were used in the current analysis on a sample of 2032 study participants (mean age 82.3y) with complete information on all MNA items. The original MNA-SF was a combination of six questions from the full MNA. A revised MNA-SF included calf circumference (CC) substituted for BMI performed equally well. A revised three-category scoring classification for this revised MNA-SF, using BMI and/or CC, had good sensitivity compared to the full MNA.
Conclusion
The newly revised MNA-SF is a valid nutritional screening tool applicable to geriatric health care professionals with the option of using CC when BMI cannot be calculated. This revised MNA-SF increases the applicability of this rapid screening tool in clinical practice through the inclusion of a “malnourished” category.
The spinel ferrite system Cu
0.8−
x
Zn
0.2Ni
x
Fe
2O
4; 0.0
≤
x
≤
0.8 is prepared by standard ceramic method. X-ray diffraction (XRD) measurements are used for analyzing the composition, lattice ...parameter, density, porosity and grain size of these compounds. The infrared spectra (IR) obtained at room temperature in the range 400–4000
cm
−1 showed two absorption spectra. The high-frequency band (
ν
1) and low-frequency band (
ν
2) are assigned to the tetrahedral and octahedral complexes, respectively. The electrical measurements of these ferrites at various compositions were investigated from room temperature up to 650
K in the frequency range (10
2–10
5
Hz). The obtained results revealed semiconductor behavior with an increasing nickel concentration with change in the slope at transition temperature
T
c. The determined
T
c is found to increase with an increasing Ni concentration. The activation energies calculated at the magnetic region are found to decrease with an increasing Ni content. The relation of the universal exponent
s
with temperature gives evidence for the presence of the large overlap polaron (LOP) hopping conduction mechanism in these compounds. The obtained results of conductivity are explained in light of the hopping conduction occurring at the octahedral B-sites.
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