Programming of 3-Axis Hybrid Kinematics CNC Machine for Rapid Prototyping Using Subtractive and Additive Processes

The paper presents the programming and program verification on a 3-axis hybrid kinematics CNC machine for rapid prototyping using subtractive and additive processes. The original hybrid (parallel-serial) 3-axis O-X glide mechanism developed to build a rapid prototyping machine and multifunctional machine tools is presented. The paper analyzes the available programming software, which can be one of the standard CAD/CAM systems or a specialized CAM system, for subtractive processes, i.e. desktop milling. For the additive processes, the software for generating G code based on the STL file as well as the possibility of simulating the machine when working is considered. To verify the program, the simulation of material removal for subtractive processes as well as the simulation of material addition for additive processes were considered. The paper presents the prototype of a hybrid kinematics CNC machine and some of the results of testing with an open control system based on the LinuxCNC

Calcium Alginate Capsules Encapsulating Rejuvenator as Healing System for Asphalt Mastic

Researchers have demonstrated that the rejuvenator encapsulation method is a promising autonomic self-healing approach for asphalt pavements, where by the self-healing system improves the healing capacity of an asphalt pavement mix. However, potentially high environmental risk via leaching of hazardous chemicals such as melamine formaldehyde renders the technology unsuitable for widespread use in road design. This paper explores the potential for the use of more environmentally friendly and economically viable rejuvenator encapsulation method, where the calcium alginate is used as rejuvenator encapsulation material. The capsule morphology and microstructure were studied using the Microscopy and X-ray tomography. Capsules thermal and mechanical strength were investigated using the Thermogravimetric analysis (TGA) and micro-compressive tests. The results demonstrated that the capsules have sufficient thermal and mechanical strength to survive the asphalt production process. The healing efficiency of the system was evaluated by embedment of calcium-alginate capsules encapsulating rejuvenator in an asphalt mastic beams and subjected to monotonic three-point bend (3PB) loading and healing programme. The results illustrated that the calcium-alginate capsules encapsulating rejuvenator can significantly improve healing performance of the asphalt mastic mix

The Role of Rejuvenators in Embedded Damage Healing for Asphalt Pavement

Rejuvenator encapsulation technique showed great potential for extrinsic asphalt pavement damage healing. Once the capsules are embedded within asphalt pavement, the healing is activated on-demand via progressing microcrack. When the microcrack encounters the capsule, the fracture energy at the tip opens the capsule and releases the rejuvenator. Then the released rejuvenator wets the crack surfaces, diffuses into and softens the aged bitumen, allowing two broken edges to come in the contact, preventing further asphalt pavement deterioration. The quality and speed of the damage repair process strongly depend on the quality of rejuvenator, thus it is important to choose a proper rejuvenator with good abilities to restore the lost properties of bitumen from ageing and show a sustainable performance after healing. To this aim, three different rejuvenators were studied and ranked based on the performance of their rejuvenated bitumen, including physical properties, rheological properties, chemical properties and the performance after re-ageing. Furthermore, these rejuvenators were encapsulated in calcium alginate capsules and the tests on these capsules indicate the diameter, mechanical resistance and thermal stability of the capsules are influenced by the encapsulated rejuvenator. The findings will benefit the development of rejuvenator encapsulation technique and the optimization of the capsule healing system towards a better healing effect in asphalt pavement

Finite size effects with variable range exchange coupling in thin-film Pd/Fe/Pd trilayers

The magnetic properties of thin-film Pd/Fe/Pd trilayers in which an embedded ~1.5 A-thick ultrathin layer of Fe induces ferromagnetism in the surrounding Pd have been investigated. The thickness of the ferromagnetic trilayer is controlled by varying the thickness of the top Pd layer over a range from 8 A to 56 A. As the thickness of the top Pd layer decreases, or equivalently as the embedded Fe layer moves closer to the top surface, the saturated magnetization normalized to area and the Curie temperature decrease whereas the coercivity increases. These thickness-dependent observations for proximity-polarized thin-film Pd are qualitatively consistent with finite size effects that are well known for regular thin-film ferromagnets. The critical exponent $\beta$ of the order parameter (magnetization) is found to approach the mean field value of 0.5 as the thickness of the top Pd layer increases. The functional forms for the thickness dependences, which are strongly modified by the nonuniform exchange interaction in the polarized Pd, provide important new insights to understanding nanomagnetism in two-dimensions.Comment: 14 pages, 5 figures, submitted to JMM

Surface-initiated growth of copper using isonicotinic acid-functionalized aluminum oxide surfaces

Isonicotinate self-assembled monolayers (SAM) were prepared on alumina surfaces (A) using isonicotinic acid (iNA). These functionalized layers (iNA-A) were used for the seeded growth of copper films (Cu-iNA-A) by hydrazine hydrate-initiated electroless deposition. The films were characterized by scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and advancing contact angle measurements. The films are Cu0 but with surface oxidation, and show a faceted morphology, which is more textured (Rq = 460 ± 90 nm) compared to the SAM (Rq = 2.8 ± 0.5 nm). In contrast, growth of copper films by SnCl2/PdCl2 catalyzed electroless deposition, using formaldehyde (CH2O) as the reducing agent, shows a nodular morphology on top of a relatively smooth surface. No copper films are observed in the absence of the isonicotinate SAM. The binding of Cu2+ to the iNA is proposed to facilitate reduction to Cu0 and create the seed for subsequent growth. The films show good adhesion to the functionalized surface

In quest of a systematic framework for unifying and defining nanoscience

This article proposes a systematic framework for unifying and defining nanoscience based on historic first principles and step logic that led to a “central paradigm” (i.e., unifying framework) for traditional elemental/small-molecule chemistry. As such, a Nanomaterials classification roadmap is proposed, which divides all nanomatter into Category I: discrete, well-defined and Category II: statistical, undefined nanoparticles. We consider only Category I, well-defined nanoparticles which are >90% monodisperse as a function of Critical Nanoscale Design Parameters (CNDPs) defined according to: (a) size, (b) shape, (c) surface chemistry, (d) flexibility, and (e) elemental composition. Classified as either hard (H) (i.e., inorganic-based) or soft (S) (i.e., organic-based) categories, these nanoparticles were found to manifest pervasive atom mimicry features that included: (1) a dominance of zero-dimensional (0D) core–shell nanoarchitectures, (2) the ability to self-assemble or chemically bond as discrete, quantized nanounits, and (3) exhibited well-defined nanoscale valencies and stoichiometries reminiscent of atom-based elements. These discrete nanoparticle categories are referred to as hard or soft particle nanoelements. Many examples describing chemical bonding/assembly of these nanoelements have been reported in the literature. We refer to these hard:hard (H-n:H-n), soft:soft (S-n:S-n), or hard:soft (H-n:S-n) nanoelement combinations as nanocompounds. Due to their quantized features, many nanoelement and nanocompound categories are reported to exhibit well-defined nanoperiodic property patterns. These periodic property patterns are dependent on their quantized nanofeatures (CNDPs) and dramatically influence intrinsic physicochemical properties (i.e., melting points, reactivity/self-assembly, sterics, and nanoencapsulation), as well as important functional/performance properties (i.e., magnetic, photonic, electronic, and toxicologic properties). We propose this perspective as a modest first step toward more clearly defining synthetic nanochemistry as well as providing a systematic framework for unifying nanoscience. With further progress, one should anticipate the evolution of future nanoperiodic table(s) suitable for predicting important risk/benefit boundaries in the field of nanoscience

Ispitivanje tačnosti pozicioniranja mašina alatki sa hibridnom kinematikom prema standardu ISO 230-2

Mašine alatke sa parelelno-serijskom (hibridnom) kinematskom strukturom predstavljaju nekonvencionalan tip mašina alatki čije karakteristike zavise od kinematske konfiguracije. Zbog toga je neophodno da se za svaki tip mehanizma izvrši posebna analiza tačnosti. Ako tačnost neke mašine opisujemo kao karakteristiku koja je posledica niza osobina mehaničke i upravljačke strukture, onda je jedan od najboljih pokazatelja karakteristika mašine stanje tačnosti pozicioniranja. Kod konvencionalnih mašina alatki koje se baziraju isključivo na serijskoj (rednoj) kinematskoj strukturi postoje standardi i preporuke (ISO 230-2, VDI DGQ 3441), koje se bave problemom tačnosti pozicioniranja. U ovom radu se opisuje merenje tačnosti pozicinoranja mašine alatke sa hibridnom kinematskom strukturom „O-X glide“ prema standardu ISO 230-2 i analiziraju se dobijeni rezultati

Pulssynchrones Ohrgeräusch, Lidschwellung, Exophthalmus, Chemose und Diplopie drei Wochen nach Schädel-Hirn-Trauma

Traumatische Karotis-Sinus-cavernosus-Fisteln sind seltene Komplikationen eines Schädel-Hirn-Traumas. Die Konsequenzen einer späten Diagnose sind progressive okuläre Symptome und Befunde wie eine Visusminderung, Augenmuskelparesen, progressiver Exophthalmus, konjunktivale Chemose, Verschluss der V. centralis retinae, sekundäres Glaukom. Zudem können eine schwere Epistaxis oder intrazerebrale und subarachnoidale Hämorrhagien auftreten. Wir präsentieren eine Patientin, die nach einem Schädel-Hirn-Trauma und dem initialen duplexsonographischen Ausschluss einer arteriovenösen Fistel nach einer Latenz von über drei Wochen eine Karotis-Sinus-cavernosus-Fistel entwickelte, die sich angiographisch darstellen und katheter­interventionell verschliessen liess. Die Symptomatik der Patientin mit pulssynchronem Geräusch, rotem, geschwollenem und schmerzhaftem Auge, Diplopie, Chemose, pulsierendem Exophthalmus mit okulärer Hypertension und progressivem Visusverlust liess mehrere differentialdiagnostische Überlegungen zu. Neben entzündlichen, mechanischen, autoimmunen, vaskulären und tumorösen Störungen war jedoch aufgrund der Anamnese mit einem Schädel-Hirn-Trauma eine traumatische Ursache der Beschwerden hochwahrscheinlich. Die rasche Beseitigung dieser Fistel ist wünschenswert, um Langzeitschäden zu vermeiden, allerdings unter der Berücksichtigung der interventionsassoziierten Komplikationen, in unserem Fall der Gefahr eines Hyperperfusionssyndroms mit konsekutiver zerebralen Einblutung. ABSTRACT: Traumatic carotid-cavernous sinus fistulas represent an uncommon complication of a head trauma. The consequences of a delayed diagnosis are progressive ocular complications such as visual loss, extraocular muscle palsy, progressive proptosis, conjuctival chemosis, retinal vein occlusion and secondary glaucoma. Moreover, severe epistaxis, intracerebral and subarachnoidal hemorrhage may occur. We present a patient who developed a carotid-cavernous sinus fistula within three weeks after a craniocerebral injury. Despite initial exclusion of an arteriovenous fistula using duplex sonography, angiography later demonstrated the carotid-cavernous sinus fistula that was successfully occluded be means of catheter intervention. The patient's symptomatology consisting of pulse synchronous bruit, red, swollen and painful eye, diplopia, chemosis, pulsating exophthalmos, ocular hypertension and progressive visual loss allowed various differential diagnoses. Apart from inflammatory, mechanical, autoimmune, vascular and tumorous disorders, a traumatic cause was highly probable considering the patient's history of craniocerebral injury. A rapid elimination of such a fistula is necessary in order to prevent long-term damage. However it is important to consider the possible complications due to the intervention, in our case the risk of a hyperperfusion syndrome with a consecutive cerebral hemorrhage