The phase transformation characteristics and isothermal oxidation behavior of ternary Ni
50
Ti
49
Ta
1
(at.%) and Ni
50
Ti
47
Ta
3
(at.%) alloys were investigated through differential scanning ...calorimetry and thermogravimetric analysis techniques in addition to surface morphology captured by scanning electron microscopy. It was found that the ambient temperature and chemical composition are important factors in the oxidation behavior of the alloys in oxygen atmosphere. The oxidation constants were linearly increased with oxidation temperatures ranging between 850 and 1150 °C. The activation energies were determined to be 283.54 kJ/mol and 249.38 kJ/mol for the Ni
50
Ti
49
Ta
1
(at.%) and Ni
50
Ti
47
Ta
3
(at.%) alloys, respectively.
Directional solidification of aluminium–copper alloys Gunduz, M; Cadirli, E
Materials science & engineering. A, Structural materials : properties, microstructure and processing,
04/2002, Letnik:
327, Številka:
2
Journal Article
Recenzirano
Directional solidification experiments have been carried out on different Al–Cu alloys as a function of solidification parameters, temperature gradient
G, growth rate
V, and composition
C
0. The ...specimens were solidified under steady state conditions with a constant temperature gradient (7.4 K mm
−1) at a wide range of growth rates (9–490 μm s
−1) and with a constant growth rate of 9.5 μm s
−1 at a wide range of temperature gradients (1.0–7.4 K mm
−1). Microstructural parameters, the primary dendrite arm spacing
λ
1, secondary dendrite arm spacing
λ
2, dendrite tip radius
R, mushy zone depth
d were measured and expressed as functions of solidification parameters,
G,
V and
C
0 by using a linear regression analysis. The results were in good agreement with previous experimental work and current theoretical models suggested for dendritic growth.
Self-injurious behavior (SIB) is associated with diverse psychiatric conditions. Sometimes (e.g., in patients with autism spectrum disorder or acquired brain injuries), SIB is the most dominant ...symptom, severely restricting the psychosocial functioning and quality of life of the patients and inhibiting appropriate patient care. In severe cases, it can lead to permanent physical injuries or even death. Primary therapy consists of medical treatment and if implementable, behavioral therapy. For patients with severe SIB refractory to conventional therapy, neuromodulation can be considered as a last recourse. In scientific literature, several successful lesioning and deep brain stimulation targets have been described that can indicate a common underlying neuronal pathway. The objectives of this study were to evaluate the short- and long-term clinical outcome of patients with severe, therapy refractory SIB who underwent DBS with diverse underlying psychiatric disorders and to correlate these outcomes with the activated connectivity networks. We retrospectively analyzed 10 patients with SIB who underwent DBS surgery with diverse psychiatric conditions including autism spectrum disorder, organic personality disorder after hypoxic or traumatic brain injury or Tourette syndrome. DBS targets were chosen according to the underlying disorder, patients were either stimulated in the nucleus accumbens, amygdala, posterior hypothalamus, medial thalamus or ventrolateral thalamus. Clinical outcome was measured 6 months after surgery and at long-term follow-up after 10 or more years using the Early Rehabilitation Barthel index (ERBI) and time of restraint. Connectivity patterns were analyzed using normative connectome. Based on previous literature the orbitofrontal cortex, superior frontal gyrus, the anterior cingulate cortex, the amygdala and the hippocampus were chosen as regions of interest. This analysis showed a significant improvement in the functionality of the patients with DBS in the short- and long-term follow-up. Good clinical outcome correlated with higher connectivity to the amygdala and hippocampus. These findings may suggest a common pathway, which can be relevant when planning a surgical procedure in patients with SIB.
Background: Lymphatic malformations (LMs) are rare congenital anomalies. The traditional treatment is surgical excision, but intralesional sclerosing agent injection is also preferred as the ...first-choice treatment because of postoperative frequent recurrences, poor cosmetic results, and high complication rate. We aimed to evaluate the efficacy of sclerosing agent injection used in the treatment of LMs in children. Materials and Methods: We retrospectively analyzed the children who were treated for LM between January 2011 and January 2022. The lesion sizes of the patients who were injected with sclerosant (Bleomycin) under sedation anesthesia, measured by ultrasound before and after the treatment, were recorded, and the difference between them was statistically evaluated. Results: Fifteen patients were retrospectively analyzed. The mean age was 45.2 ± 14.1 months. Of these, ten (66.6%) were male and five (33.3%) were female (F/M = 1/2). The mean age of male patients was 55 ± 20.1 months; the mean age of female patients was 25.8 ± 11. Seven patients had a single dose, two had twice, and six had three and more. The mean measurable size of macrocystic lesions before treatment was 55.2 ± 28.4 mm; after treatment, it was 23.8 ± 18.2 mm. Although no measurable shrinkage was detected in microcystic lesions, it was observed that the lesion shrank to allow surgical resection. With the statistical analysis, it was seen that there was a statistically significant difference between the dimensions before and after the treatment (P < 0.05) and the sclerosant injection had a great effect on the treatment (R: 0.89). Conclusion: Intralesional injection of bleomycin is less effective for microcystic or mixed-type LMs, but provides an effective reduction for a safe surgical procedure. It is an effective treatment for macrocystic lesions.
This study was designed to determine whether a new form of treatment of diabetic retinopathy (DR) was acceptable to patients and whether reduction in the maximal activity of rods in diabetes could ...affect the progress of DR.
In 12 patients, trans-lid retinal illumination of one eye was employed during sleep to prevent the depolarisation of rods and thus reduce their metabolic activity.
A headband was used to place a source of chemical light over one eye, with its fellow as a control.
Colour contrast thresholds were measured before and after a period of treatment in treated eyes, and the changes were compared to those in untreated fellow eyes, and areas of 'dark retinal anomalies' (microaneurysms, dot haemorrhages) were measured at the same time points.
Patients found this intervention to be acceptable, and no adverse effects were noted. In the majority of cases, and for each outcome measure, the treated eyes improved relative to their fellows. The intervention significantly reduced the tritan thresholds in treated eyes relative to their fellows (P=0.03), and the area of dark retinal anomalies decreased in treated eyes and increased in untreated eyes, with a similar probability.
The study showed that this intervention is safe. Although the study was not powered to study efficacy, the results are promising and consistent with other reports that indicate the retina in DR is suffering from hypoxia; however, further trials should be undertaken.
Aluminium–silicon irregular eutectic alloy was melted in a graphite crucible in vacuum. This alloy was directionally solidified at a constant growth rate,
V (8.3
μm/s) and at different temperature ...gradients,
G (2.0–7.8
K/mm) and also with a constant
G (7.8
K/mm) and different
V (8.3–498.7
μm/s) in the Bridgman type directional solidification furnace. The interflake spacings,
λ
i, were measured from both transverse and longitudinal sections of the specimens. The relationships between interflake spacings,
λ
i and solidification parameters
V and
G were obtained by linear regression analysis method. The variations of interflake spacings,
λ
i with
V,
G and undercoolings, Δ
T
i, were investigated and the relationships between them were examined. Operating parameters
φ and
η which reflect the spacing adjustment mechanism were obtained.
λ
i
2
V,
λ
i Δ
T
i, Δ
T
i
V
−
a
,
λ
i
3
G and Δ
T
i
G
−
b
values were determined by using
λ
i,
V,
G and Δ
T
i, values. The results obtained in this work have been compared with the eutectic theory and previous experimental results.
An experimental analysis is presented to correlate the secondary dendrite arm spacing
λ
2
and dendrite tip radius
R
with growth rate
V
and Mg content
C
0-Mg
of Al–Cu–Mg ternary alloys. Under constant ...temperature gradient
G
(4.84±0.13 K mm
−1
), a series of directional solidification experiments were performed at five different growth rates
V
(16.7–83.3 μm/s) and five different Mg contents
C
0-Mg
in Al–5 wt.% Cu–(0.5–5) wt.% Mg alloys. Solid–liquid interface was investigated from the longitudinal sections of the quenched samples, and
λ
2
and
R
were measured on the dendrite tips. The dependencies of
λ
2
and
R
on
V
and
C
0-Mg
were determined. The experimental results showed that the values of
λ
2
and
R
decrease as
V
and
C
0-Mg
increase at a constant
G
. The present exponent values related to
V
are found to be slightly lower than the values of the theoretical models and previous experimental works; however,
C
0-Mg
exponent values are found to be much lower than the theoretical models and previous experimental works. The ratio of the secondary dendrite arm spacing to the dendrite tip radius is 2.09±0.15, in good agreement with the scaling law. At a constant
C
0-Mg
, the values of
VR
2
were found to slightly increase with the ascending
V
. However, as
C
0-Mg
increases, the values of
VR
2
decrease.
•K of the A707 alloy decreases from 154 to 124 W/m K with increasing temperature.•The αTCC value for the studied alloy was determined to be -4.17 × 10−4 K.•The σ of A707 alloy exponentially decreases ...with increasing temperature.•Thermal diffusivity decreased from 61.6 × 10−6 to 50.2 × 10−6 m2/s with increasing T.
In the present work, the thermal conductivity, electrical conductivity, enthalpy of fusion, specific heat capacity and thermal diffusivity of the A707 alloy (Al–4.5 Zn–1.2 Mg–0.15 Cr–0.15 Zr wt.%) have been investigated. Phase identification of the studied alloy was investigated with energy dispersive X-ray analysis and X-ray diffraction techniques. Thermal conductivity of as-cast A707 alloy was measured using Comparison Cut Bar Method in the temperature range of 300–800 K. With the increase of temperature, thermal conductivity decreased gradually in as-cast A707 alloy. The electrical conductivities of the sample were obtained with the Wiedemann–Franz equation by using the measured thermal conductivity values. Thermal conductivity coefficients for the alloy were obtained from the graphs of thermal conductivity versus temperature. The enthalpy of fusion and the specific heat capacity during the transformation were also determined. Thermal diffusivity changes were calculated as a function of temperature through the obtained thermal data.
The grain boundary groove method has been successfully used to measure solid-liquid interfacial energies, σSL, experimentally for binary eutectic and peritectic systems, multi-component systems as ...well as pure materials and for opaque materials as well as transparent materials. It was shown that the grain boundary groove method can be use to obtain σSL for any alloy system provided that the prepared alloy sample can be held at the evaluated temperature for a long enough time with a very stable temperature gradient. In order to show the applicability of the groove method to any system, a part of the Al-Zn phase diagram was chosen. Equilibrated grain boundary groove shapes for solid Alα solution (Al-30wt%Zn) in equilibrium with AlZn liquid (Al-60wt%Zn) have been directly observed with a radial heat flow apparatus. The Gibbs-Thomson coefficient, Γ, was determined with a numerical method using observed groove shapes. The measured thermal conductivities of the solid Alα solution and AlZn liquid phases and the temperature gradient in the solid phase at the solid-liquid interface were used for the calculation of Γ and then σSL was determined using the Gibbs-Thomson equation. The grain boundary energy for the same system was also obtained from the observed groove shapes. The results of the work were compared with the results of the related experimental works.
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