Focal Diameter Research Articles

Linearly Scaling Molecular Dynamic Modeling To Simulate Picosecond Laser Ablation of a Silicon Carbide Crystal.

A molecular dynamics model for picosecond laser ablation of nanoscale silicon carbide crystals was established by linearly scaling the laser focal diameter, and the correlation between the molecular dynamic simulation of the nanoscale and the experimental reproduction of the microscale was achieved. The calculation accuracy of the molecular dynamic model was verified by ablating the surface of silicon carbide wafers with a laser pulse width of 37 ps. On this basis, this paper further investigated the influence of the laser pulse width and fluence on the surface ablation damage and modification width, threshold, and lattice temperature. The results showed that, when the laser pulse width is higher than 10 ps, the silicon carbide damage threshold increases with increasing the pulse width, while the modification threshold is almost unaffected by the pulse width. In addition, the influence of crystal orientation has been studied, and laser irradiation along the [1-100] crystal orientation induces a higher peak temperature, larger damage, and modification width and threshold, followed by irradiation along the [0001] crystal orientation and lowest along the [11-20] crystal orientation. Finally, with the linear scaling value increasing, the spatial distribution of the laser energy field deviates more from the actual situation, resulting in the calculated results being more consistent with the experimental results. Through this paper, it is demonstrated that this linearly scaled molecular dynamics model can be used to study laser ablation results over tens of micrometers.

Suppressed oncogenic molecules involved in the treatment of colorectal cancer by fecal microbiota transplantation

Dysbiosis of the intestinal microbiota is prevalent among patients with colorectal cancer (CRC). This study aims to explore the anticancer roles of the fecal microbiota in inhibiting the progression of colorectal cancer and possible mechanisms. The intestinal microbial dysbiosis in CRC mice was significantly ameliorated by fecal microbiota transplantation (FMT), as indicated by the restored ACE index and Shannon index. The diameter and number of cancerous foci were significantly decreased in CRC mice treated with FMT, along with the restoration of the intestinal mucosal structure and the lessening of the gland arrangement disorder. Key factors in oxidative stress (TXN1, TXNRD1, and HIF-1α); cell cycle regulators (IGF-1, BIRC5, CDK8, HDAC2, EGFR, and CTSL); and a critical transcription factor of the innate immune signal pathway (IRF5) were among the repressed oncogenic targets engaged in the FMT treatment of CRC. Correlation analysis revealed that their expressions were positively correlated with uncultured_bacterium_o_Mollicutes_RF39, Rikenellaceae_RC9_gut_group, and negatively correlated with Bacillus, Marvinbryantia, Roseburia, Angelakisella, Enterorhabdus, Bacteroides, Muribaculum, and genera of uncultured_bacterium_f_Eggerthellaceae, uncultured_bacterium_f_Xanthobacteraceae, Prevotellaceae_UCG-001, uncultured_bacterium_f_Erysipelotrichaceae, uncul-tured_bacterium_f_Lachnospiraceae, uncultured_bacterium_f_Ruminococcaceae, Eubacterium_coprostanoligenes_group, Ruminococcaceae_UCG-005, and uncultured_bacterium_f_Peptococcaceae. This study provides more evidence for the application of FMT in the clinical treatment of CRC.

Development workflow based on in situ synchrotron investigations to optimize laser processing of copper pins

To design future laser manufacturing processes for welding of copper materials, more and more high-end analysis methods are required. A fundamental process understanding by analyzing cause-and-effect relations of process dynamics using inline in situ diagnostics allows for an improved description of laser material interaction. Strategies for a reliable and robust welding process are derived from the findings. In this study, a four-step advanced methodical approach is presented and discussed. In the first step, a fundamental process description of the geometry of the vapor capillary and the formation of weld defects is developed. Therefore, welds on electrolytic tough pitch copper (Cu-ETP) and CuSn6 are carried out to analyze the temporal and spatial vapor capillary dynamics depending on laser power, welding speed, and focal diameter. This fundamental process understanding is transferred to the welding of copper pins in the form of I-pins. For this purpose, impurities and imperfections were applied to the pin surface to investigate the effects on the process result. As a third step, strategies by means of laser intensity distributions were adapted to compensate for imperfections in the welding process. Finally, a sensor vision system is adapted for ideal welding results. Investigations are based on in situ synchrotron analysis at Petra III, DESY in Hamburg. For the experiments, a TRUMPF TruDisk laser (100/400 μm fiber diameter), a TRUMPF TruFiber 6000P (50/100 μm fiber diameter), and a single-mode fiber laser (14 μm fiber diameter) were used. The focal diameter was adjusted with the optical system depending on the investigation.

Contactless Single Cell Extraction from Monolayer Cell Culture Using A MEMS Acoustic Droplet Ejector.

To achieve a contactless and damage-less extraction of a single (or a few) human retinal pigment epithelial (RPE) cell(s) from a cell monolayer with acoustic droplet ejection. An acoustic droplet ejector based on a self-focusing acoustic transducer (SFAT) is designed, microfabricated, and placed on a precision movable stage that aligns it to the targeted cell(s) in a Petri dish. The device delivers 20.1 MHz focused ultrasound (FUS) with a focal diameter of 100 μm, which ejects droplets capable of extracting and transferring only the targeted cell(s) from a monolayer. The extraction and collection of 1-10 cells are successfully demonstrated. The number of ejected cells can be controlled by the FUS pulse width. As confirmed by fluorescence-based cell viability assays and re-culture experiments, the ejected cell(s) and remaining monolayer cells are intact without damage after cell ejection. Furthermore, real-time reverse transcription polymerase chain reaction (RT-PCR) tests for both housekeeping genes (GAPDH and β -actin) and RPE-specific genes (MITF, PEDF, and PMEL17) show no significant difference between the acoustically ejected cells and those collected manually with a micropipette. The proposed technology realizes a contactless, damage-free extraction of cells with high spatial resolution and precise control of the number of cells ejected, with a simple setup. This powerful technology not only enables efficient, high-precision cell extraction for quality check applications but also opens new avenues for other advanced biotechnologies such as bioprinting.

Application effect of 18F-FDG PET/CT technique in diagnosis and prognosis evaluation of lymphoma

The objective of the study was to research diagnostic and prognostic values of 18F fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with diffuse large B-cell lymphoma (DLBCL). The diagnostic sensitivity (Sen) of PET/CT (94.75 %) was remarkably higher than 83.56 % of B-US. Age ≥ 65 years old, maximum focal diameter ≥5 cm, clinical stages III-IV, systemic symptoms, increased lactate dehydrogenase level, high modified international prognostic index score, Ecog score ≥1, B-cell lymphoma 2 (Bcl-2) gene, MYC protein expression rate, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were all factors that influenced the recurrence or progression of DLBCL. With higher MTV and TLG, patients would have a greater probability of recurrence or progression. 18F-FDG PET/CT showed a high diagnostic Sen in lymphoma lesions, and could accurately guide clinical staging. Combined with clinical parameters, laboratory indicators, and metabolic parameters, prognostic indicators of patients could be evaluated more accurately.

Reducing Feature Size in Laser Implantation Texturing.

Embossing rolls are used in a variety of sectors to transfer surface textures to a product. Textures on the rolls are typically achieved by material-removal techniques, resulting in craters in the surface of the roll. The wear resistance of the surfaces is improved by additional coating technologies. A novel process offering improved surface design freedom and which negates the need for post-coating techniques is the embedding of micro-meter-sized ceramic particles in the surface of the roll. This can be achieved through micro-additive processing. This work presents and discusses experimental results of surface texturing through locally derived laser-induced melt pools in which ceramic particles are dissolved. This process is termed laser implantation, or laser dispersing. Using this technology, dome-shaped surface structures with significantly increased hardness compared to the bare steel can be achieved. Reported results in the literature focus on implantations with diameters ranging from 150 μm to 400 μm and heights ranging from 10 μm to 30 μm. However, features with smaller diameters and heights are desired for technology adoption to permit a wider range of surface roughness. This paper presents and discusses the experimental results of implantations with a diameter smaller than 150 µm, with heights between 1 μm and 15 μm. For that purpose, a Nd:YAG laser source (focal diameter 70 μm, pulse durations from 3 to 15 ms, pulse power from 20 to 50 W average) was used to induce a melt pool driving the particle embedding.

Efficacy of colchicine and melatonin in the treatment of rat endometriosis model: An animal study

ObjectiveThis study investigates the therapeutic effects of colchicine and melatonin on endometriotic implants in an experimentally created endometriosis model in rats. Study designForty-four adult female Wistar albino rats weighing between 260 and 300 g, 8 weeks old, were selected for the study. The unilateral uterine horn of rats with a bicornuate uterus was excised for 1 cm, washed with sterile saline, incised longitudinally, and the endometrium was exposed. A 0.5*0.5 cm endometrial tissue sample taken with a scalpel was implanted with suturing (4/0 Vicryl) to the abdominal wall. Forty-four rats were divided into four groups. Group 1 was randomized as the endometriosis group (control), Group 2 as endometriosis + colchicine treatment, Group 3 as endometriosis + melatonin treatment, and Group 4 as the endometriosis + melatonin + colchicine treatment group. The colchicine (Sigma Chemical Co., St Louis, Missouri) group was administered orally at a dose of 0.1 mg/kg, and the Melatonin group orally at a dose of melatonin (20 mg/kg per day). Treatment continued daily for 30 days. ResultsIn the post-treatment focal diameter measurements, the endometrial focal diameter in the colchicine and colchicine + melatonin group was significantly lower than the control group (p=0.026). Bcl-2 levels of the colchicine group were lower than the control group and the melatonin group (p=0.021). ConclusionColchicine and melatonin reduce adhesion to the peritoneal surface in ectopic endometrial cells. It also acts by increasing apoptosis and decreasing cell survival.

Clinicopathological features affecting the efficacy in 131I ablation therapy of papillary thyroid carcinoma with lymph node metastasis.

Lymph node metastasis is the major cause of increased recurrence and death in patients with papillary thyroid carcinoma (PTC). We evaluate the clinicopathologic factors affecting excellent response (ER) in patients with PTC with lymph node metastasis following operation and 131I ablation therapy. A total of 423 patients with PTC with lymph node metastasis who underwent thyroidectomy and postoperative 131I ablation therapy were enrolled. The relationship between clinicopathological factors affecting ER achievement was analyzed. Multivariate analysis showed that the foci diameter (≤1 cm), unifocal, combination with Hashimoto's thyroiditis (HT), lymph node metastases rate (LR) (≤40%), no postoperative lymph node metastasis, low preablative stimulated thyroglobulin (ps-Tg) level (≤3.87 ng/mL), and the time of 131I ablation therapy (one time) were positively correlated with the ER achievement [odds ratio (OR): 1.744, 3.114, 3.920, 4.018, 2.074, 9.767, and 49.491, respectively; all p < 0.05]. The receiver operating characteristic (ROC) curves showed that the cutoff values of ps-Tg and LR were 4.625 ng/mL and 50.50%, respectively. The AUC of ROC of ps-Tg and LR for predicting ER achievement was 0.821 and 0.746, respectively. The Tg and the cumulative risk of non-ER elevated with the increase of LR, especially for the high-level ps-Tg (>4.625 ng/mL) group. The foci diameter and number, combination with HT, LR, and ps-Tg level are independent factors for ER. Ps-Tg level and LR are valid predictive factors for the efficacy of 131I therapy in patients with PTC. The predictive value of the cumulative risk of non-ER can be improved by the combination of ps-Tg and LR.

Direct laser patterning of ruthenium below the optical diffraction limit

We describe a method that can be used to produce ruthenium/ruthenium oxide patterns starting from a ruthenium thin film. The method is based on highly localized oxidation of a small surface area of a ruthenium film by means of exposure to a pulsed laser under ambient conditions. Laser exposure is followed by dissolution of the un-exposed ruthenium in a NaClO solution, which leaves the conductive, partially oxidized ruthenium area on the substrate. Spatially selective oxidation, material removal, and, by implication, patterning, are, therefore, achieved without the need for a photoresist layer. Varying the exposure laser parameters, such as fluence, focus diameter, and repetition rate, allows us to optimize the process. In particular, it enables us to obtain circular Ru/RuO2 islands with a sub-diffraction-limited diameter of about 500 nm, for laser exposure times as short as 50 ms. The capability to obtain such small islands suggests that heat-diffusion is not a limiting factor to pattern Ru by laser heating on a (sub-)micron scale. In fact, heat diffusion helps in that it limits the area where a sufficiently high temperature is reached and maintained for a sufficiently long time for oxidation to occur. Our method provides an easy way to produce metallic Ru/RuO2 (sub-)micron structures and has possible applications in semiconductor manufacturing.

In Situ Synchrotron Investigations of Beam Diameter Influence on Vapor Capillary Formation during Laser Beam Welding of Copper Alloy with a Blue Laser Beam Source

Laser beam welding as a reliable tool for high-precision joining of batteries or microelectronics is more and more the choice for achieving reproducible results in production processes. In addition to a high automation capability, the precise control of the energy deposition into the material plays an important role, especially when highly reflective materials, such as copper or aluminum, must be welded together. Alongside the use of highly brilliant fiber lasers in the near-infrared range with a focal diameter of a few tens of micrometers, diode lasers in the wavelength range of 445 nm are increasingly being used. Here, beam diameters of a few hundred micrometers can be achieved. With a wavelength of 445 nm, the absorptivity in copper can be increased by more than a factor of 10 compared to a near-infrared laser beam sources in solid state at room temperature. This paper presents the in situ X-ray observation of laser welding processes on CuSn6 with a laser beam source with a wavelength of 445 nm using synchrotron radiation at DESY Petra III Beamline P07 EH4 in Hamburg, Germany. For the experiments, the laser radiation was focused via two separate optics to focal diameters of 362 µm and 609 µm. To characterize the dynamics of the vapor capillaries depending on the different focal diameters dF, the parameters were varied with respect to laser power PL and feed rate v. For the investigations, a synchrotron beam of 2 × 2 mm2 in size with a photon energy of 89 keV was used, and the material samples were analyzed by means of phase-contrast videography to show the boundaries between solid, liquid, and gaseous material phases. The results of this paper show the welding depths achieved and how the geometry of the vapor capillary behaves by changing the focal diameter, laser power and feed rate.

Clinical features, treatment strategies, and prognosis of epithelioid inflammatory myofibroblastic sarcoma in children: a multicenter experience.

Inflammatory myofibroblastic tumors (IMTs) are a spectrum of tumors that range in morphology and biological behavior from benign, intermediate, to apparently malignant and epithelioid inflammatory myofibroblastic sarcoma (EIMS) is one of the malignant subtypes. This study tried to provide experience and new ideas for treating this rare disease. This study retrospectively analyzed and followed up 12 children with EIMS admitted to Beijing Children's Hospital, Baoding Children's Hospital, and Children's Hospital of Chongqing Medical University from August 2016 to May 2022. Of the 12 children, 7 were male and 5 were female, with a median age of 74.50 [interquartile range (IQR), 61.50-90.00] months. Of these patients, eight had a single lesion and four had multiple lesions. The maximum diameter of the single tumor foci was 19.30 cm, the full meridian of the multiple tumor foci target lesions was 32.67 cm, and the median maximum tumor size was 11.99 (IQR, 7.80-15.70) cm. The site of disease was the abdominopelvic cavity in eight cases, the thoracic cavity in two cases, the maxillofacial region in one case, and the larynx in one case. The clinical manifestations were predominantly elevated body temperature (n=8). There was one case of ROS1 fusion mutation and nine cases of ALK fusion mutation. Of the 12 children, 6 were biopsied at the initial diagnosis and 6 were surgically treated. Follow-up treatment included preoperative neoadjuvant chemotherapy (n=4), peritoneal thermal perfusion therapy (n=2), targeted therapy (n=3), postoperative chemotherapy (n=5), and radiotherapy (n=3). The follow-up time was 14.50 (IQR, 10.50-31.50) months, with eight cases of tumor-free survival, two cases of death, and two cases of loss of follow-up. EIMS in children is extremely rare and clinically aggressive. The clinical presentation is nonspecific, and the initial diagnosis of the tumor is often large. Mutations in the ALK gene are common in EIMS. Surgery is the mainstay of EIMS treatment, and patients benefit from a multidisciplinary combination that includes targeted therapies, with long-term prognosis remaining subject to ongoing follow-up.

Design and Characterization of the New FAHEX100 Concentrator of PSA's SF60 Solar Furnace

The facets of the old Mc Donnell Douglas concentrator of Plataforma Solar de Almería –PSA- SF60 solar furnace were degraded after thirty years of service, which had a great influence on its thermal response and efficiency, as the reflectivity decreased significantly due to the reflective surface being corroded and scratched. That is why, it was decided to replace them by new facets with higher reflectivity and better optical conditions.&#x0D; This paper describes the new facets, as well as the new support structure and the assembly and alignment of the concentrator facets. Finally, the technical characteristics of the new concentrator, and the power, size and flux distribution on the focus, are presented.&#x0D; For the new facets we selected a thin, hexagonal-shaped mirror bonded to an aluminum plate.&#x0D; Therefore, new facets with improved optical conditions were designed and manufactured and, for the assembly a new tubular structure was used to conform the new FAHEX100 concentrator&#x0D; To anticipate the behavior of the new FAHEX100 concentrator, a model was built in Tonatiuh, for which a geometric analysis of the facets was previously performed by means of photogrammetry.&#x0D; Once the facets were mounted on the concentrator, they were aligned by the Reverse Ilumination Method -RIM–, and the flux distribution on the focus was measured with a CCD camera.&#x0D; The performance of the SF60 solar furnace was improved significantly with the new FAHEX100 concentrator, including power, peak concentration, flux distribution on the focus, focus diameter and optical error σopt.

Femtosecond reductive Laser Sintering under multiple focus conditions for rapid production of conductive copper layers

Reductive laser sintering is an advantageous alternative to conventional precious metal- or mask-based processes for the electrification of polymers and has been demonstrated in a variety of sensor applications. Ultrashort pulsed lasers promise precise control of the energy applied during sintering and ablation. Besides fine tracks, microelectronic circuits include wide contact pads, which leads to time-consuming processing with small laser spot sizes. The use of larger focal diameters, which results in wider lines and thus a higher metallization rate, is accompanied by a loss of structure resolution. We show the influence of focusing on the femtosecond reductive laser sintering of copper(II) oxide on cyclic olefin copolymers. While small focus diameters down to 23 µm provide high accuracy, increasing the laser power and the focus diameter up to 400 µm significantly accelerates the process, first by enlarging the line width and second by increasing the scanning speed due to the exposure time. Two-dimensional copper electrodes for 23 µm and 200 µm focal diameters were generated by hatching individual lines and compared with respect to their morphology. The enlarged spot can be used for high-speed generation of electrodes with a surface conductivity of 117 mΩ/sq. Hybrid processes with production under combined focusing conditions are presented for the first time.

Clinical value of ultrasound parameters PI, TTP, and MTT in assessing cervical lymph node metastasis of papillary thyroid carcinoma.

To determine the clinical value of ultrasound in assessing cervical lymph node metastasis (CLNM) in papillary thyroid carcinoma (PTC). The medical records of 179 PTC patients treated in Shandong Provincial Qianfoshan Hospital between March 2016 and March 2019 were collected. The patients were assigned to a transfer group (54 cases) and a non-transfer group (125 cases) according to their pathologic results. The ultrasound parameters (peak intensity (PI), time to peak (TTP), and mean transit time (MTT)) of the two groups were compared. Then, multivariate logistic regression was used to analysis the results, and receiver operating characteristic (ROC) curves were plotted to evaluate the value of risk factors in predicting CLNM. The transfer group showed notably lower PI, TTP and MTT than the non-transfer group (P<0.001), and focus diameter, microcalcification, multiple foci, PI, TTP, and MTT were identified as independent risk factors for LNM in patients (P<0.05). According to the ROC curve, the areas under the curves (AUCs) of microcalcification, multiple foci, and PI were all smaller than 0.7; the AUCs of focus diameter and MTT were smaller than 0.8, and the AUC of TTP was 0.855. PI, TTP, and MTT all decrease in PTC patients with CLNM, and TTP has a strong predictor for CLNM in them, with an AUC of 0.855.

Investigation on different laser-powder alignments and their influence on part properties in high-speed Directed Energy Deposition

Efficient high-speed directed energy deposition via laser beam (HS DED-LB) requires precise knowledge of the powder focus location and diameter. The alignment of the laser and powder focus ensures maximum powder efficiency and minimizes potential defects caused by unmolten powder due to insufficient power input during the laser-powder interaction time. The focal characteristics, such as diameter or focus position, are dependent on the nozzle used and are affected by the powder gas jet parameters, like shielding gas- or carrier gas flow. This study analyses the effects of individual powder gas jet parameters on the focal position and -diameter. Additionally, the impact of different laser-powder alignments (unaligned and aligned) for HS DED-LB is investigated by adjusting the laser focus to the measured powder focus position. The analysis of these different settings focuses on the sample’s height, relative density, and microhardness.

Millimeter-wave metalens with extended depth of focal on the short focal length

Millimeter wave (mm-wave) metalens has shown significant progress in recent years. However, the existing works in the literature on the extended depth of focal (EDOF) metalens present limitations for mm-waves. More specifically, the good performance of the EDOF requires a focal length larger than the radius of the metalens, which limits its miniaturization applications. In this work, mm-wave metalens with EDOF on the short focal length was proposed. The focus distribution was equally divided and the spin Hall effect was employed to guarantee the uniform focus intensity. From our analysis, it was demonstrated that the designed metalens can work at mm-wave frequencies and also achieve extended focal depth at half the metalens’ radius. The proposed metalens has the unique characteristics of short focal length (The focal diameter ratio is 0.36) with EDOF. Moreover, it can be used in the mm-wave field for short-distance imaging and detection, also the development of high-power metalens applications may be facilitated.

Morphometric Analysis of Lateral Cervical Lymph Node Metastasis in Papillary Thyroid Carcinoma Using Digital Pathology.

Digital pathology uses digitized images for cancer research. We aimed to assess morphometric parameters using digital pathology for predicting recurrence in patients with papillary thyroid carcinoma (PTC) and lateral cervical lymph node (LN) metastasis. We analyzed 316 PTC patients and assessed the longest diameter and largest area of metastatic focus in LNs using a whole slide imaging scanner. In digital pathology assessment, the longest diameters and largest areas of metastatic foci in LNs were positively correlated with traditional optically measured diameters (R = 0.928 and R2 = 0.727, p < 0.001 and p < 0.001, respectively). The optimal cutoff diameter was 8.0mm in both traditional microscopic (p = 0.009) and digital pathology (p = 0.016) evaluations, with significant differences in progression-free survival (PFS) observed at this cutoff (p = 0.006 and p = 0.002, respectively). The predictive area's cutoff was 35.6 mm2 (p = 0.005), which significantly affected PFS (p = 0.015). Using an 8.0-mm cutoff in traditional microscopic evaluation and a 35.6-mm2 cutoff in digital pathology showed comparable predictive results using the proportion of variation explained (PVE) methods (2.6% vs. 2.4%). Excluding cases with predominant cystic changes in LNs, the largest metastatic areas by digital pathology had the highest PVE at 3.9%. Furthermore, high volume of LN metastasis (p = 0.001), extranodal extension (p = 0.047), and high ratio of metastatic LNs (p = 0.006) were associated with poor prognosis. Both traditional microscopic and digital pathology evaluations effectively measured the longest diameter of metastatic foci in LNs. Moreover, digital pathology offers limited advantages in predicting PFS of patients with lateral cervical LN metastasis of PTC, especially those without predominant cystic changes in LNs.

High-Speed Laser Beam Welding of Magnesium Alloy AZ31 for Enhancing the Mechanical Properties

Laser beam welding is still the focus of research all over the world since new laser sources with more brilliance, higher power, or higher efficiency are being developed. High brilliance leads to thinner fibers when solid-state lasers are used. For welding applications, a thin beam, respective a small focus spot is recommended for low heat input resulting in less deformation. The edge preparation of the welding pieces must be as accurate as possible, and a zero gap is recommended. In earlier research, it was shown, that the gap bridging capacity could be enhanced by the wobbling of small focus spots, as well as refining the grain size in the weld zone by decreasing the focus diameter. Inventions in the optics, like the beam splitting into a core and a ring part, avoid the use of a scanner and can lead to better gap bridging. Nevertheless, the use of a brilliant beam, resulting in a small focus in combination with high power can result in very high welding velocities, just limited by the used machinery. In the present study, a disk laser with 4 kW maximum power and 100 μm focus spot was used to weld 2 mm thick magnesium AZ31 sheets at speeds up to 20 m/min. As expected, the seam width becomes smaller with raising velocity, and some underfill and access material occurred on the surface and the root of the welded sheets. Surprisingly, the texture of the weld seam changed from random at low velocity to a more pronounced texture at high speed with respect to the basal texture of the plate base material. This influences the mechanical behavior, namely the strain to fracture, of the welded joints positively. The high-speed weldments are compared to state-of-the-art weldments of magnesium AZ31, in terms of mechanical strength and elongation to fracture, based on the texture analysis.

Near-infrared femtosecond laser direct writing of microchannel and controlled surface wettability

The application of femtosecond laser in fabricatingpoly (methyl methacrylate) microchannels and the alteration of wettability by inducing a change in chemical functional groups has already been established and reported in literature.However, studies on the application of femtosecond laser for modification of surface wettability without significant chemical modification,are yet to be reported. The paper reports work on an expedition of femtosecond (Ytterbium-doped fiber) laser ablation working at the near-infrared wavelength (1030 nm) tuning the wettability behavior comprising of hydrophilic and hydrophobic state on the basis of the surface morphology created below the focal beam diameter. The initial part revolves around the investigation of near-infrared femtosecond laser ablation for achieving microcavity and microchannel below the focal beam diameter. The latter part deals with laser surface modification for attaining both hydrophilic and hydrophobic surfaces. The study obtained a high degree of hydrophobicity, with a maximum water contact angle of 129.05°at a laser energy of 40 μJ and pulse laser overlap of 96%. It was also possible to attain a minimum water contact angle of 56.35°using a laser pulse energy of 40 μJ and pulse overlap of 0 %. The reported work avoids surface chemical modification for controlling the wettability.

Prevalence of intracranial artery stenosis in a general population using 3D-time of flight magnetic resonance angiography

BackgroundData on prevalence of intracranial artery stenosis (ICAS) in Western populations is sparse. The aim of the study was to assess the prevalence and risk factors for ICAS in a mainly Caucasian general population. MethodsWe assessed the prevalence of ICAS in 1847 men and women aged 40 to 84 years who participated in a cross-sectional population-based study, using 3-dimensional time-of-flight 3 Tesla magnetic resonance angiography. ICAS was defined as a focal luminal flow diameter reduction of ≥50 %. The association between cardiovascular risk factor levels and ICAS was assessed by multivariable regression analysis. ResultsThe overall prevalence of ICAS was 6.0 % (95 % confidence interval (CI) 5.0–7.2), 4.3 % (95 % CI 3.1–5.7) in women and 8.0 % (95 % CI 6.3–10.0) in men. The prevalence increased by age from 0.8 % in 40-54 years age group to 15.2 % in the 75-84 years age group. The majority of stenoses was located to the internal carotid artery (52.2 %), followed by the posterior circulation (33.1 %), the middle cerebral artery (10.8 %) and the anterior cerebral artery (3.8 %). The risk of ICAS was independently associated with higher age, male sex, hypertension, hyperlipidemia, diabetes mellitus, current smoking and higher BMI. ConclusionsThe prevalence of ICAS in a general population of Caucasians was relatively high and similar to the prevalence of extracranial internal carotid artery stenosis in previous population-based studies.