Bcc Type Research Articles

Multiple, non-syndromic and non-metastatic pigmented basal cell carcinoma mimicking nodular melanoma: a rare presentation in Indian patient

Basal cell carcinoma is most common cutaneous malignancy having exposure to ultraviolet radiation as the most important predisposing factor. It could be solitary or multiple, in which case they can be associated with variety of syndromes. Out of various clinical types of BCC pigmented bcc can mimic sometimes malignant melanoma and in which case dermoscopy and skin biopsy can be helpful to differentiate. Metastasis of BCC is a rare phenomenon and it depends on various factors like tumour size, site, depth, histological type etc. Here we describe an interesting case of primary, non-syndromic, multifocal BCC which was initially diagnosed as melanoma but later on based on dermoscopy and histology diagnosed and successfully treated as BCC.

CUTANEOUS SQUAMOUS CELL CARCINOMA AT NATIONAL HOSPITAL OF DERMATOLOGY AND VENEREOLOGY: A FOLLOW-UP RETROSPECTIVE STUDY

Objectives: This study assessed the postoperative follow-up attendance of patients with cutaneous squamous cell carcinoma (cSCC) who underwent management at the National Hospital of Dermatology and Venereology, following the protocol based on the American Academy of Dermatology (AAD) guidelines of care for the management of cutaneous squamous cell carcinoma in 2018 and the classification of low and high-risk cSCC according to the National Comprehensive Cancer Network (NCCN). Materials and Methods: A retrospective study involving 60 cSCC patients was conducted. The monitoring included recurrent cancerous lesions, new cancerous lesions (cSCC, BCC, melanoma, and other types), detection of metastatic lesions (lymph node and distant metastases), late complication monitoring (bad scarring), and mortality monitoring. Results: Depending on their stage and risk factors, cSCC patients underwent tumor removal by wide local excision (61.7%) or Mohs surgery (38.3%). Regional lymph node screening for metastasis included clinical examination, ultrasound, cytology, or sentinel lymph node biopsy (SLNB). Distant metastases in cSCC were infrequent, accounting for 1.7%, mainly presenting as lymph node metastases (6.7%). Patients were re-examined at least 5 years after treatment, revealing 4 of 56 patients with lymph node metastasis, 1 with bone metastasis, and 4 in the high-risk group who succumbed in the subsequent period. Conclusion: The management of cSCC, following the AAD guidelines and risk classification by NCCN, is effective, with treatment modifications as needed and strict monitoring being imperative. Received 19 June 2023Revised 18 September 2023Accepted 25 November 2023

Growth rate and substrate temperature dependent magnetic and magneto-microstructural properties of sputtered Fe-Co-Al thin films

This work reports the effect of growth rate and substrate temperature on the structural, magnetic and magneto-microstructural properties of Fe-Co-Al alloy thin films. 75 nm thick Fe-Co-Al films were deposited on Si 〈100〉 substrates at room temperature by high power impulse magnetron sputtering at different growth rates viz., 0.67–1.6 Å/s. All the films exhibited a uniform composition of about Fe60Co25Al15 irrespective of growth rates. In addition to this, all the films crystallized in single phase with bcc type structure. Growth rate was found to have a considerable impact on the magnetic properties of Fe-Co-Al thin films. Film grown at 1.3 Å/s exhibited an in-plane magnetic anisotropy with large saturation magnetization combined with low coercivity when compared with other films. To improve the magnetic properties further, Fe-Co-Al films were also processed at different substrate temperatures (Ts) viz., 300, 400 and 500 °C. Substrate temperature of about 300 °C was found to have beneficial effect on the soft magnetic characteristics of Fe-Co-Al films. While the crystal structure did not show any perceptible change with processing conditions, magnetic microstructures traced from magneto optic Kerr microscopy displayed substantial change. Upon increase in substrate temperature, during magnetization reversal process, magnetic domain images traced along the easy magnetization direction magnetization showed transformation from branched band domains (as-deposited) → wide band domains (Ts = 300 °C) → less periodic branched band domains (Ts = 400 °C) → ripple domains (Ts = 500 °C). Attempts were made to correlate the achieved magnetic properties in Fe-Co-Al with magnetic microstructures.

Thickness dependent magnetic anisotropy studies in sputtered Fe-Co-Al thin films

In this paper, an attempt has been made to evolve a structure-magnetic microstructure – magnetic property correlations in sputtered Fe-Co-Al thin films grown at different thicknesses. Fe-Co-Al thin films with various thicknesses viz., 25, 50, 100, 150 and 200 nm were deposited on Si 〈100〉 substrates at room temperature. Structural studies revealed that the films are crystalline in nature with bcc type structure. The crystallinity and average crystallite size deduced from X-ray diffraction studies were found to increase with increase in film thicknesses. Surface microscopy investigations also showed an increase in grain size with film thickness. All the films exhibited a predominant in-plane (IP) magnetic anisotropy. While the saturation magnetization was found to decrease with increase in film thickness, the coercivity exhibited an increasing trend. A maximum saturation magnetization of about 1300 emu/cc has been realized for the 50 nm thick film. Angular dependent magnetization studies indicated anisotropic magnetic behaviour along the plane of the film. Magnetic microscopy studies carried out using Longitudinal magneto-optical Kerr microscopy showed presence of 180° band domain along the easy direction of magnetization for lower thickness films. With subsequent increase in film thickness a combination of ripple and band domains were observed. With further increase in film thickness, presence of only ripple domains has been observed. The deterioration of IP magnetic properties with increase in film thickness was correlated with the magnetic microstructural observations.

Design and development of low density, high strength ZrNbAlVTi high entropy alloy for high temperature applications

Superior high temperature strength, better thermodynamic stability and good workability are some of the desirable attributes of structural materials for next generation nuclear reactors. In this regard, the present study involves the development of a low density, equiatomic ZrNbVTiAl High Entropy Alloy (HEA) for nuclear applications. The alloy was designed using a combination of thermodynamic simulations and first principle techniques and later synthesized using levitation melting to ensure better purity and compositional homogeneity. The melted alloy possessed lower density (5.76 g/cm3) and higher hardness (5.7 GPa) in comparison to conventional structural materials like austenitic steel. Detailed characterization of the alloy showed the presence of bcc type phase along with small fractions of Al- Zr type intermetallics in as-solidified condition. The mechanical properties of the equiatomic ZrNbVTiAl alloy were studied using compression testing at room temperature and up to 1000 °C. The alloy exhibited superior specific yield strength as well as dynamic recrystallization at high temperatures resulting in the breaking of cast structure, thereby reflecting its appreciable workability. The alloy also showed a satisfactory elastic modulus (128 GPa) when measured using ultrasonic technique. The experimentally measured values of elastic moduli of alloy were compared with the values obtained through Density Functional Theory (DFT) simulations and the results matched within acceptable range. Results from the present study indicates that the equiatomic ZrNbVTiAl alloy could be a suitable candidate for light weight, high temperature and high strength structural applications.

Additive manufacturing of a Co-Cr-W alloy by selective laser melting: In-situ oxidation, precipitation and the corresponding strengthening effects

• The in-situ oxidization and precipitation behaviors in laser powder bed fusion (LPBF) processed Co-Cr-W alloy were investigated. • The corresponding strengthening behaviors of observed nano-oxide inclusions and nano-precipitates were studied. • A nano-oxide with high Si content, together with a bcc type Co5Cr3Si2 nano-precipitates were reported for the first time in LPBF Co-Cr-W alloys. • The strengthening mechanism of widely dispersed nano-oxides was disclosed, whose strengthening contribution was calculated to be ∼158 MPa. Additive manufacturing exhibits great potentials for the fabrication of novel materials due to its unique non-equilibrium solidification and heating process. In this work, a novel nano-oxides dispersion strengthened Co28Cr9W1.5Si (wt.%) alloy, fabricated by laser powder bed fusion (LPBF), was comprehensively investigated. During the layer-by-layer featured process, in-situ formation of Si rich, amorphous, nano-oxide inclusions was observed, whose formation is ascribed to the high affinity of Si to oxygen. Meanwhile, distinctive body-centered cubic (BCC) Co5Cr3Si2 nano-precipitates with an 8-fold symmetry were also confirmed to appear. The precipitates, rarely reported in previous studied Co-Cr alloys, were found to tightly bond with the in-situ oxidization. Furthermore, the morphologies, the size distributions as well as the microstructure of the interface between the matrix and the inclusions were investigated in detail and their influence on the tensile deformation was also clarified. The existence of transition boundaries between these inclusions and the matrix strongly blocked the movement of dislocations, thereby increasing the strength of the alloy. It was understood that when the plastic deformation proceeds, the fracture occurs in the vicinity of the oxide inclusions where dislocations accumulate. A quantitative analysis of the strengthening mechanism was also established, in which an additional important contribution to strength (∼ 169 MPa) caused by the effects of in-situ formed oxide inclusions was calculated.

Clinical and histopathological characteristics of primary and recurrent basal cell carcinoma: a retrospective study of the patients from a tertiary clinical centre in the northern Poland.

IntroductionBasal cell carcinoma (BCC) is the most common malignant neoplasm of the skin. Management of patients with recurrent BCC remains a current clinical issue. Data concerning BCC recurrence rates as well as characteristics of this group of patients in the Polish population are scarce.AimIdentification and analysis of clinical, epidemiological and histopathological factors influencing BCC recurrence.Material and methodsHistopathological diagnoses of BCC patients treated by surgical methods at the Department of Dermatology, Venereology and Allergology, Medical University of Gdansk, between 2013 and 2018, were retrospectively analysed. The analysis included 1097 tumours diagnosed in 802 patients, of which 1061 were primary BCC (pBCC) and 36 – recurring BCC (rBCC).ResultsIn the analysed cohort, rBCCs constituted 3.3% of cases. 49.8% of pBCCs occurred in women; while in the rBCC group – 47.2%. The most common histopathological type was infiltrative BCC, however, it was significantly more prevalent in rBCCs (36.9% and 52.8%, respectively). The average maximum size of pBCC was 12.3 ±8.8 mm, while of rBCC 18.4 ±15.1 mm (p = 0.036). The most common location of both pBCC and rBCC was the nose (tumours in this localization constituted 23.2% and 25.0%, respectively).ConclusionsIn the analysed cohort a relatively low percentage of rBCC was found. Among analysed risk factors, the most important ones were the infiltrative histopathological type of BCC and the non-radical treatment of the primary tumour.

Molecular alterations in basal cell carcinoma subtypes

A number of genes have been implicated in the pathogenesis of BCC in addition to the Hedgehog pathway, which is known to drive the initiation of this tumour. We performed in-depth analysis of 13 BCC-related genes (CSMD1, CSMD2, DPH3 promoter, PTCH1, SMO, GLI1, NOTCH1, NOTCH2, TP53, ITIH2, DPP10, STEAP4, TERT promoter) in 57 BCC lesions (26 superficial and 31 nodular) from 55 patients and their corresponding blood samples. PTCH1 and TP53 mutations were found in 71.9% and 45.6% of BCCs, respectively. A high mutation rate was also detected in CSMD1 (63.2%), NOTCH1 (43.8%) and DPP10 (35.1%), and frequent non-coding mutations were identified in TERT (57.9%) and DPH3 promoter (49.1%). CSMD1 mutations significantly co-occurred with TP53 changes (p = 0.002). A significant association was observed between the superficial type of BCC and PTCH1 (p = 0.018) and NOTCH1 (p = 0.020) mutations. In addition, PTCH1 mutations were significantly associated with intermittent sun exposure (p = 0.046) and the occurrence of single lesions (p = 0.021), while NOTCH1 mutations were more frequent in BCCs located on the trunk compared to the head/neck and extremities (p = 0.001). In conclusion, we provide further insights into the molecular alterations underlying the tumorigenic mechanism of superficial and nodular BCCs with a view towards novel rationale-based therapeutic strategies.

Facial Reconstruction after Surgical Excision of Basal Cell Carcinoma

Background and Aim of Study: The aim of this study was to evaluate the outcomes of different facial flapsused for reconstruction after surgical excision of basal cell carcinoma.Patients and Methods: Patients with BCC of the facial area were 128 cases. The cases were treated, andfollowed up between January 2012 and April 2018. Results: There was a single case of tumor recurrencein the frontal area. Also scar formation in female patient over 60 years old was noted. The case of scarformation was notes after frontal flap which used for treatment of nasal defect.Otherwise, there was no patient with any complications (like infective wound, keloid, scar formation,ischemia, or necrotic tissues), have been seen among the rest of the cases at the end of our study on 2020. Inall male cases that treated with skin graft after excision of the tumor in frontal area which was 8 patients; atthe end of follow up period, the color of skin and tissue harmony was coordinated.Conclusion: No specific flap or graft can be done for all the types of BCC, we should choose the mostappropriate flap or graft. Recurrent ratio was very low.

‘Efficacy and safety of imiquimod 5% cream for basal cell carcinoma: a meta‐analysis of randomized controlled trial’: a critical appraisal

Jia and He aimed 'to compare the efficacy and safety of imiquimod with other treatments in patients with basal cell carcinoma' (BCC). Meta-analysis of studies that included patients with histologically confirmed BCC treated with imiquimod 5% cream compared with all other treatments, including vehicle, excisional surgery, cryosurgery, fluorouracil and methyl aminolaevulinate photodynamic therapy. The main outcome measures included histological and composite clearance rates, success rates, complete response rates, tumour-free survival and adverse events. Thirteen studies with a total of 4265 patients were included in the review. Pooled analyses comparing imiquimod with all or any of the listed comparators, including vehicle, demonstrated higher histological clearance rates [risk ratio (RR) 9·28, 95% confidence interval (CI) 5·56-15·5; P < 0·001], higher composite clearance rates (RR 34·2, 95% CI 21·3, 55·1; P = 0·001), no significant difference in success rates (RR 0·98, 95% CI 0·89-1·08; P = 0·73), higher complete response rates (RR 3·15, 95% CI 1·55-6·38; P = 0·001), no significant difference in tumour-free survival (RR 1·15, 95% CI 0·98-1·35; P = 0·088) and increased incidence of adverse events (RR 2·00, 95% CI 1·39-2·88; P < 0·001). The authors state that 'imiquimod significantly exhibited benefit effect in improving the histological/composite clearance rates' compared with other treatments, and they suggest it could be used as the first-choice treatment for patients with BCC. The main concerns related to the article by Jia and He are that the research question is replicative, it makes little sense to combine all BCC types in a meta-analysis, and it also makes no sense to combine an active treatment against a combination of vehicle and other active treatments. There are also concerns about bias related to the use of the same study data more than once in a meta-analysis. Furthermore, we have identified an example of covert duplicate publication, which further compounds the profusion of misleading systematic reviews.

Incidence of betapapillomaviruses in the tumour and perilesional healthy skin in patients with basal cell carcinoma depending on sex, age, hair colour, tumour subtype, its location and dissemination.

IntroductionBasal cell carcinoma (BCC) is the most common skin cancer in the Caucasian population. It is believed that infections caused by viruses from the genus betapapillomavirus (β-HPV) might be associated with the risk of BCC, but the spread of data on the prevalence of the virus in biopsies is significant.AimTo assess the presence and diversity of β-HPV in skin samples taken from the tumour and a fragment of healthy skin from the patients with BCC, as well as checking the correlation of factors listed below and presence of β-HPV infection in the studied patients.Material and methodsThe study was conducted on the skin biopsies from 73 patients with histopathologically confirmed BCC. The following data were collected from patients: sex, age, hair colour and tumour location. Using the polymerase chain reaction (PCR) test, the presence of β-HPV infection was detected in the tested samples. PCR and reverse hybridization assay were also used to genotype 25 types of β-HPV.ResultsA statistically significant correlation was found between the sex and BCC type, BCC type and tumour location, BCC type and exposure to UV radiation, as well as between the hair colour and tumour location. The correlation between the BCC type and the number of tumours and HPV types detected was also noted.ConclusionsPreliminary studies suggest that one of the risk factors for development of infiltrating lesions is the presence of a single HPV 93 infection, but further research is needed to confirm these assumptions.

A Five-Year Retrospective Analysis of Basal Cell Carcinoma: A Monocentric Study.

ObjectiveOur aim in this study is to define the histopathological subtypes, body site distribution, and incidence rates of single or multiple of BCCs. The study is conducted on patients from a single institution in Istanbul which has a migrant-receiving population reflecting that of the country overall.MethodWe retrospectively analyzed data concerning 896 cases of BCC seen between 2014 and 2018. Data about patient demographics (age and sex), tumor diameter,its anatomic localization, histological type, presence of ulceration, lymphovascular/perineural invasion, and single or multiple tumor formations were retrieved from both the hospital’s automated system and archived records of the pathology clinic.ResultsOur univariate analysis showed that the patients’ age, tumor size, and tumor multicentricity were all significantly related to their gender (p=0.011, p=0.001, and p=0.021, respectively). Further, age, male gender, and tumor size were all significantly related to tumor multicentricity (p=0.003, p=0.021, and p=0.001, respectively). BCC was most commonly found in male, and the diameters of the BCC tumors were also larger in male patients. Multiple BCC was more frequently seen in older and male patients, and the tumors had larger diameters in these groups. The nodular type of BCC was the most frequently seen type in all age groups.ConclusionAs our study is the first BCC study that has the greatest number of cases in Turkey and as Istanbul reflects the population of Turkey, it is important for the data of BCC cases in Turkey.

Influence of composition and as-cast structure on the mechanical properties of selected high entropy alloys

The paper investigates the influence of several alloying elements (Al, Mn, Cu, Ti and Si) and the typology of the as-cast structure on the mechanical properties of high entropy alloys. A theoretical criteria analysis was carried out on the Al–Cr–Cu–Fe–Mn–Ni, Al–Cr–Co–Fe–Ni–Ti, Al–Cr–Fe–Mn–Ni and Al–Cr–Cu–Fe–Mn–Ni–Si alloy systems to select appropriate compositions for application requirements. The alloys were prepared by induction melting and were cast in copper mold. As-cast samples were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and mechanical analyses. The experimental results partially validated the criteria predictions. Alloys with higher Al content presented most predominantly BCC type phases. Ti and Cu were found enriched in the interdendritic area. Si influenced greatly the as-cast morphology of the dendrite structure. The substitution of Co with Mn generated a significant improvement of the mechanical properties. A composition-structure-properties correlation was described in the paper. The morphology of the as-cast structure had a strong impact on the final properties of the alloys. The Al–Cr–Fe–Mn–Ni alloy showed the best overall characteristics, with a hardness of 412 HV and a compressive strength of 895 MPa.

Equilibrium hydrogen pressures in the V–H system from first principles

Equilibrium hydrogen pressures over hydrogenated vanadium, i.e., crystalline VHx with 0≤x≤2, are estimated based on first-principles calculations to assess the suitability of V-based alloys for use as hydrogen storage materials. For intermediate H contents (x = 0.5 and 1) corresponding to partial site occupancies, a multistep process was used to determine the ground-state structures. First, a large number of configurations with H on tetrahedral (T) or octahedral (O) sites in bcc–type lattices were ranked in terms of energetical stability sans vibrational contributions. Next, phonon calculations were carried out for the lowest-energy structures identified in the first step and zero-point energies added to the electronic energies. Hydrogen pressures for V-VH0.5 and VH-VH2 equilibria were then calculated using these ground-state free energies and thermodynamic equations. Calculation of vibrational energies was simplified by identifying the linear relationship between H content and zero-point energy, which depends only on the type of sites occupied by H atoms. Whereas H atoms preferentially occupy T sites when vibrational terms are ignored, their inclusion leads to H atoms preferentially occupying O sites in both VH0.5 and VH at 0 K. Inclusion of vibrational energy also leads to a better match with reported experimental hydrogen pressures highlighting its importance when assessing the stabilities of different H distributions in metal lattices. The method outlined consists of a more exhaustive configurational search than has been considered previously, and should be useful for systematic investigation of a wide variety of V-based alloys.

Evaluation of compressive properties of SLM-fabricated multi-layer lattice structures by experimental test and μ-CT-based finite element analysis

The influence of inherent imperfections should be systematically investigated to ensure the safety and utilization of additive manufacturing-fabricated multi-scale parts and structures. Herein, two different types of multi-layer lattice sandwich panels, BCC and BCCZ, are prepared by selective laser melting (SLM) using the AlSi10Mg material. X-ray micro-computed tomography (μ-CT) is employed to capture the realistic geometrical information of lattice struts. Based on the statistical characteristics, a novel finite element model is established, which considers the specific non-uniform distribution of geometrical imperfection. Uniaxial compressive tests are performed to evaluate the influence of defects and number of layers on the overall mechanical performance and energy absorption capability. The results reveal that the diameter deviation of struts is changed with the change of strut location and built angle. In terms of compressive modulus and initial crushing strength, the prediction results of the reconstruction model are consistent with experimental results as compared to the as-designed and statistical average models. The layer-by-layer crushing behavior is the main failure mode for the multi-layer lattice panels. With the increase of layers number, the densification strain and crash load efficiency increased, whereas the specific energy absorption gradually decreased due to the impact of boundary conditions and failure modes.

Recurrence rate of basal cell carcinoma in patients submitted to skin flaps or grafts

BackgroundBasal cell carcinoma is the most common type of skin cancer. Although the literature provides a great deal of information on the recurrences of basal cell carcinoma, studies about these indices addressing only the cases in which flaps and/or grafts have been performed for surgical reconstruction of the excision of this tumor are still lacking. ObjectivesTo evaluate rates of recurrence of basal cell carcinoma submitted to conventional surgery with pre-established margins and reconstruction by flaps or grafts. MethodsA retrospective and observational study was performed through the analysis of 109 patients, who met inclusion criteria with 116 basal cell carcinomas submitted to conventional surgery and pre-established safety margins, requiring reconstruction through a graft or cutaneous flap. This work was performed the small surgeries sector of Dermatology of the Specialty Outpatient Clinic of the University Hospital of the State University of Londrina, between January 1, 2011 and December 31, 2015. The following data were collected and inserted in an Excel worksheet: name, registration number of the hospital patient, sex, age, tumor location, histopathological type of BCC, procedure performed (type of flap and/or graft), follow-up time, recurrence. ResultsOf the 116 procedures, there were recurrences in 3 cases (2.6%) that were located in the nasal region and related to sclerodermiform or micronodular histological types. Study limitationsRetrospective nature of the study. ConclusionThe present study of the dermatology department of this university hospital showed a low rate of recurrence of basal cell carcinoma in cases where flaps and/or grafts were used in the surgical reconstruction.

Perihilar cholangiocarcinoma - correlation of bismuth type IV with T- and UICC-stage

Background: Perihilar cholangiocarcinoma (PHCC) is the most frequent bile duct cancer. Bismuth-Corlette classification (BC) is often regarded as relevant for therapy by nonoperative disciplines. Thus, patients with BC type IV (tumor extension on right and left main bile duct) are sometimes considered as irresectable and a palliative therapy is initiated without an assessment of a surgeon. Methods: All patients with a PHCC (n = 118) were prospectively evaluated in a database in the period from 2008 to 2015 and retrospectively analysed with the focus on performed resection, the BC (pathologic result), the TNM classification and the UICC stage. Results: In 88 of 118 patients (74.6%) resection could be performed with curative intent. Type IV of BC was present in 47/88 cases (53.4%) and was by far the most common (type I n=4, II n = 7, III n = 26). Of these 47 patients with BCC type IV following T-stages: T1 n = 2 - T2a n = 10 - T2b n = 29 - T3 n = 4 - T4 n = 2 and UICC-stages: I n = 1 - II n = 25 - IIIa n = 3 - IIIb n = 16 - IVa n = 2 - IVb n = 0 were achieved. R0 resection was performed in 33/47 (70.2%) patients. A negative lymph node status (N0) was seen in 30 of the 47 patients. Conclusion: PHCC with type IV BC are most often resectable, and often low T- and UICC-stages are present as well. Any patient suspected of having a PHCC should be presented at a center for liver surgery to evaluate exploration. In the vast majority of cases, resectability can only be clarified through exploration and depends on the T-stage.

Interplay of magnetic anisotropies on the magnetostrictive behavior of Fe–Co thin films

This paper reports the structure, microstructure, domain imaging and magnetostrictive properties of Fe50Co50 thin grown on Si substrates with different thicknesses namely 40, 80, 100 and 120 nm. Structural studies revealed that the films are crystalline in nature with bcc type structure. Magnetization studies exhibited predominant in-plane magnetic anisotropy for all the films. In addition to this films grown with higher thicknesses also showed co-existence of out-of-plane magnetic anisotropy along with in-plane magnetic components. Angle dependent hysteresis measurements indicated presence of weak uni-axial magnetic anisotropy along the plane for all the films. Longitudinal magneto-optic Kerr microscopy studies revealed nucleation of reverse domains for the film grown with low thickness. Wide band domains with few zig–zag branched features have been observed for the films grown with higher thicknesses. Magnetic force microscopy investigations along the out-of-plane direction showed increase in magnetic phase contrast with increase in film thicknesses. Magnetostriction derived from the deflection measurements are found to decrease with increase in film thicknesses. Presence of competing anisotropies has been found to be prominent reason for the decrease in the magnetostriction with increase in film thickness.

LOCALIZED ELECTRONIC SURFACE STATES IN METALLIC STRUCTURES

We present theoretical models to study the localized electronic surface states in metallic structures. The materials under study have been chosen with different types of cubic meshes, fcc, sc and bcc. The calculation method used is closely related to the Linear Combination of Atomic Orbitals (LCAO) in the tight-binding method. We consider three cases: each of the atoms is described by a single atomic orbital of [Formula: see text]-, [Formula: see text]- and [Formula: see text]-type orbitals. In order to solve the rectangular secular equations of the systems under study, the phase field matching method is involved. In particular, we apply our approach to calculate the localized electronic surface states of some metals: (i) Chromium and Silver having, respectively, bcc and fcc structure and described as [Formula: see text]-type orbital. (ii) Nickel with sc crystallization and described by [Formula: see text]-type orbital. (iii) Palladium (Pd) given in fcc crystallization and described by [Formula: see text]-type orbital. The obtained results illustrate spatial edge effects between the bulk modes and the localized electronic states of the metallic surfaces over the three orientations of high symmetry path. We observe many localized states above and below the bulk band range. In addition, the relaxation effect on the surface layer has been investigated to compute the localized electronic surface state in this case and illustrate the lift of the degeneracy compared to the first calculations based on an ordered surface. The spacing geometry caused by the relaxation on the surface has been determined by using the Molecular dynamic algorithm and Morse interatomic potential.

Pressure Effects on the Structural Evolution of Monatomic Metallic Liquid Hafnium

Structural evolution of monatomic metallic liquid hafnium under high pressures of 0-50 GPa has been investigated by molecular dynamics (MD) simulations using the tight-binding many body potentials during rapidly solidified processes. The structural evolution and glass formation process have been analyzed by using pair distribution functions (PDF), Wendt-Abraham (RWA) parameter, Honeycutt-Andersen (HA) and Voronoi tessellation (VT) methods. When the system has been cooled with a cooling rate of 2x1013 Ks-1, the glassy states are obtained for P≤40 GPa pressures and the crystalline phase is obtained at P=50 GPa pressure. The number of face-centered cubic (fcc) and hexagonal close-packed (hcp) (fcc + hcp) type bonded pairs increase dramatically, while the number of perfect icosahedra, distorted icosahedra and body-centered cubic (bcc) type bonded pairs decreases with increasing of pressure. This is an indication that the solidification process of the system begins with nucleation in the liquid and that nucleation growth with increasing pressure continues to develop. The results show that the variation of local atomic bonded pairs is of great importance to understand the glass formation and crystallization process. However, it has been observed that the applied high pressure weakened icosahedral order and increased the fraction of other clusters in glassy hafnium at low temperatures. Furthermore, it has been observed that all glass transition temperatures (Tg), main bond types and main base clusters change with increasing pressure.