Search

Al–Zn–Mg alloys have attracted significant interest in the automotive industry owing to their high strength and light weight. Precipitation hardening is the primary mechanism by which these alloys are strengthened, meaning the analysis of the shape, size, and fraction of the precipitates is crucial. In this study, the interfacial structure of precipitates, which influences the mechanical properties of alloys, was investigated. Aberration-corrected scanning transmission electron microscopy studies revealed the atomic structure of the unique V-shaped interface structure of the η1precipitates, which are the most prevalent among the η precipitates produced in this alloy. The structure was investigated from an energetic perspective using first-principles calculations, which revealed that the formation of the V-shaped interface structure increased the stability through strain relaxation in both the aluminum matrix and η1. The results provide valuable insights into the formation and growth mechanisms of precipitates, paving the way for further advancements in this field.

Objective Frontonasal dysplasia (FND) is a rare congenital condition. Its major features include hypertelorism, a large and bifid nasal tip, and a broad nasal root. We present our technique of septal L-strut reconstruction using costal cartilage.Design Retrospective review from June 2008 and August 2017.Methods Under general anesthesia, 6 patients with FND underwent septal reconstruction using costal cartilage via open rhinoplasty. We reconstructed the nasal and septal cartilaginous framework by placing columellar struts and cantilever-type grafts.Results The patients ranged in age from 6 to 13 years old. All were female. The follow-up period ranged from 8 months to 2 years; we encountered no postoperative complications (infection, nasal obstruction, or recurrence). All patients were satisfied with their nasal appearance.Conclusions Although the results were not entirely satisfactory from an esthetic point of view, we found that FND can be treated via septal reconstruction with costal cartilage and that the clinical outcomes are reliable and satisfactory. Our approach is a useful option for FND patients.

Graphical abstract:

Supplemental digital content is available in the text.

Supplemental Digital Content is available in the text

In light of climate change and greenhouse gas reduction, countries around the world are doing their part to develop various types of eco-friendly energy. In this context, the Shihwa Tidal Power Plant is an advanced energy generation infrastructure which uses the resources of the sea, a project that pioneers and practices low-carbon, green growth engineering. Not only as an advanced energy generation infrastructure but also it is an eco-friendly infrastructure that resurrected ‘the dead lake’, which had suffered extreme water pollution due to cutoff in seawater circulation after the completion of the tide embankment in 1994. By circulating the water of the lake, new mud flats have appeared in the upstream area, an area once submerged due to the embankment. These new mud flats are providing new shelters for various organisms, thus transforming the lake into an eco-friendly, life-giving one. Most tidal power plants are difficult to construction due to geological features. The Sihwa tidal power plant was developed harmoniously by utilizing the unique geological features and tidal power plant principles on the West coast of the Korean peninsula. Shihwa Tidal Power Plant is a special and differentiated development example of renewable energy production and environmental improvement along with the significant water quality improvement effect of Shihwa Lake due to increased seawater exchange rates. This article therefore presents the review of Shihwa Lake’s environmental issues and eco-friendly energy production process with the aim to identify the good practices, the challenges as well as the lessons learnt from their experience. This development will be another case of a country seeking to develop new marine energy. This is also a good practice of improving the environment of freshwater lakes in coastal areas.

Numerical finite element method (FEM) calculation results reveal that the effective strain differs between the ductile Zr-based bulk metallic glass and brittle Hf-based bulk metallic glass (BMG) during rolling at room temperature. The current results demonstrated that the deformation mechanism of ductile Zr-based bulk metallic glass can be explained by perceptibility of multiple shear bands formation, however, the deformation mechanism of brittle Hf-based bulk metallic glass is represented by uniformly distribution of effective strain through overall specimen rather than localized into shear band. The variation of stress and the distribution of effective strain change significantly near the surface region of a Hf-based bulk metallic glass plate with increasing number of rolling passes. Under elasto-plastic deformation by cold rolling, the brittle Hf-based BMG has a thickness strain (εt) of −0.012, and the neutral effective strain (εeff) is 0.011 at the thickness direction, respectively. We present experimental confirmation that when the applied effective strain can be adjusted to below 1.1% during elasto-plastic deformation then even the brittle as-cast Hf-based BMG can be deformed up to 44% thickness reduction and 23% width expansion after multi-pass cold rolling without fracture by localization of shear stress.

Metallic alloys containing multiple principal alloying elements have created a growing interest in exploring the property limits of metals and understanding the underlying physical mechanisms. Refractory high-entropy alloys have drawn particular attention due to their high melting points and excellent softening resistance, which are the two key requirements for high-temperature applications. Their compositional space is immense even after considering cost and recyclability restrictions, providing abundant design opportunities. However, refractory high-entropy alloys often exhibit apparent brittleness and oxidation susceptibility, which remain important challenges for their processing and application. Here, utilizing natural-mixing characteristics among refractory elements, we designed a Ti38V15Nb23Hf24refractory high-entropy alloy that exhibits >20% tensile ductility in the as-cast state, and physicochemical stability at high temperatures. Exploring the underlying deformation mechanisms across multiple length scales, we observe that a rare ß'-phase plays an intriguing role in the mechanical response of this alloy. These results reveal the effectiveness of natural-mixing tendencies in expediting high-entropy alloy discovery.

In this study, cold reduction process of the tubular metal is applied to manufacture the drive shaft for the rear wheel drive system. With this method during forming process, chip forming such as hobbing and broaching method is not involved. The manufacturing process is as follows; the tube which the sheet is formed and welded to by roll forming machine, is mounted on a suitable mandrel. This mandrel has an external toothing which corresponds to internal toothing of the final product. During axial moving and rotating of the workpiece, forming operation is carried out in lengthwise direction of the toothing. This forming rolls is positioned on the roll head and have a rolling axis vertical with the one of a mandrel. The total forming load needed in the cold reduction process is separated into numerous forming steps along the entire cylindrical length of the zone to be formed. In the process of cold forming on the profiled mandrel during the impact forming operation, material is pushed into depression of toothing of a mandrel mainly in a radial direction. Finally splines can be generated on the surface of components and overall elongated. If the process parameter such as the length of forming per 1rotation of 1roll is not optimized, the impact force from the rolls of the forming process causes geometrical defects. So the optimal parameters such as feeding and rotating speed of workpiece and the forming length should be properly determined. And the effects of the weld line positioning on the formability of the forming process is analyzed to minimize the generation of the defects such as crack on the surface of splined zone.

Orbital floor fractures are among the more challenging injuries faced by plastic surgeons. Enophthalmos is defined as backward, usually downward, displacement of the globe into the bony orbit. We describe reconstruction of the orbital floor slope in orbital floor fractures that prevents postoperative complications, especially posttraumatic enophthalmos. Thirty-three patients with orbital floor fractures were treated using reconstruction of the orbital floor slope between April 2009 and July 2010. The patients ranged in age from 12 to 54 years. There were 31 males and 2 females. All patients were operated on using a transconjunctival approach under general anesthesia. The orbital floor was reconstructed with poly-l/d-lactide sheets in all cases. Preoperatively, 23 Float1patients (69%) had enophthalmos, and 12 patients (36%) had symptomatic diplopia. The enophthalmos was corrected in 20 patients (86%), and the diplopia resolved in 10 (83%). Extrinsic ocular movement was impaired preoperatively in 1 patient (3%), but resolved after surgery. No patient had impaired visual acuity preoperatively or postoperatively. The results suggest that orbital floor reconstruction considering the orbital floor slope is a safe, reliable method with fewer complications that is more effective at preventing posttraumatic enophthalmos.

The phase stability of amorphous Ge2Sb2Te5(GST) films affects the performance and reliability of phase change memory (PRAM) devices. The viscosity and the glass forming ability of nitrogen (N)-doped amorphous GST films were investigated in terms of thermomechanical behavior using wafer curvature measurements. The viscosity which increased by two orders of magnitude was observed in the N-doped amorphous GST film by measuring the stress relaxation accompanied by bimolecular structural relaxation. The glass forming ability ($\Delta T_{\text{x}}$), difference between the glass transition temperature ($T_{\text{g}}$) and the crystallization temperature ($T_{\text{c}}$), of GST increased as the nitrogen contents increased. These increases in the viscosity and $\Delta T_{\text{x}}$ indicate the retardation of atomic diffusion in amorphous GST and the stabilization of the amorphous phase.

Pneumosinus dilatans is a rare disease in which 1 or more paranasal sinuses are dilated without functional alteration. The frontal sinus is the most commonly affected site, with involvement of the maxillary sinus being rare. Asymmetrical facial contour is the most common sign, and nasal obstruction and pain may also be present. We describe 6 cases of maxillary pneumosinus dilatans with histories of protrusion of the malar region. Plane radiography and computed tomography revealed abnormal expansion of the maxillary sinus without thinning of the bony wall, leading to a diagnosis of maxillary pneumosinus dilatans. Surgical decompression and maxilloplasty were achieved by electrical burring, greenstick downward fracture, or ostectomy of the anterior wall of the maxillary sinus and subsequent repositioning of the removed bony fragments with miniplates. The postoperative course was uneventful, and facial contours were improved on physical and radiologic examination. No recurrence was detected in any case, and good cosmetic results were achieved. In this article, the authors present surgical options for the treatment of pneumosinus dilatans of the maxillary sinus, including a review of the literature.

Alloying, or mixing of multiple metallic elements, is the classical way of novel materials development since the Bronze age. Increased numbers of principal elements expand the compositional space for alloy design vastly, leading to nearly endless possibilities of unexpected and unique materials properties. In contrast to bulk alloying processes represented by casting of molten metal mixtures, the fabrication of multicomponent alloy (MCA) nanostructures such as nanoparticles and nanofoams with more than three elements is often challenging, and a few methodologies for directly synthesizing alloy nanostructures up to denary systems have been suggested recently. However, forming alloy nanoparticles inside another metal matrix, instead of inside aqueous media in wet-chemical synthesis, is a fairly well understood strategy in terms of physical metallurgy. Extracting those alloy nanophases from the matrix could provide an alternative way to fabricate novel MCA nanostructures.

This article describes a qualitative research project that examined pen pal letters exchanged between children in Virginia, USA, and Malawi in Sub‐Saharan Africa. The goal was to study the nature of communication between students living in these two very different cultural contexts. The results of this study indicated that there were three primary themes within the pen pal letters between the primary and elementary students: daily life and culture, language, and connections. The students enjoyed sharing information about all aspects of their daily life and culture with their pen pals, and they were able to communicate meaningfully with one another on these topics. The students followed the language patterns established by one another in their letters, and they made attempts to use terminology that would be readily understandable to one another. Each theme found in the study is explored, and the value of using pen pal exchanges to support the development of literacy and cultural understandings is discussed. Recommendations are made for establishing pen pal exchanges in international contexts.

Summary: Antibacterial silicone rubbers (SR) were prepared by platinum curing and peroxide curing of a silicone compound containing the synthetic antimicrobial monomer 1-ethyl‐6‐fluoro‐7‐{4‐[2‐hydroxy‐3‐(2‐methylacryloyloxy)‐propyl]piperazin‐1‐yl}‐4‐oxo‐1,4‐dihyroquinoline‐3‐carboxylic acid (MQ) and its polymer PMQ. The effects of the two curing systems on the mechanical properties were compared. Tensile strength and elongation at break of the platinum‐cured SR decreased with increasing concentrations of MQ and PMQ. For the peroxide curing system, the elongation at break increased with increasing concentrations of the antimicrobial agents. The antibacterial activity of the prepared SR was examined by the shake flask test against Staphylococcus aureus and Escherichia coli, which are representative of Gram‐positive and Gram‐negative bacteria, respectively. All compounds showed excellent antibacterial activities against these two types of bacteria.Structure of acrylated norfloxacin.

Summary: Various output heaters were extruded with CB-filled HDPE composites. The effects of crystallinity on the PTC and thermal reproducibility of the quenched, annealed, and E‐beam crosslinked heaters were examined during heating and cooling cycles at an applied voltage of 220 V. Conductor resisitivity and PTC effect of the heaters increased as crystallinity of composites increased. During the thermal cycling test, significant changes in heater‐output and resistivity for annealed and quenched heaters were observed. However, for quenched/E‐beam radiated and annealed/E‐beam radiated heaters no significant difference was found. These results indicate that the annealing process did not affect the thermal and electrical reproducibility of HDPE/CB heaters significantly.Acetylene black aggregates in polyethylene matrix.

Summary: Flexible heaters were prepared by extruding platinum-catalyzed silicone rubber compound with electroconductive carbon black (CB) and SnO2/Sb coated titanium dioxide (TiO2). Two types of acicular‐shaped TiO2 with average particle sizes of 1.7 and 5.2 µm, and two types of spherical‐shaped TiO2 with average particle sizes of 0.3 and 2.5 µm were selected. Thermoelectric switching phenomena were investigated for the silicone rubber/CB/TiO2 system. Positive temperature coefficient (PTC) was significant when the acicular filler was added rather than spherical ones. Resistivity change and thermal reproducibility of the extruded heaters were also investigated by applying periodically AC voltage of 220 V. The heaters containing acicular‐shaped TiO2 exhibited excellent electrical reproducibility.Scanning electron micrograph of the fractured surface of the extruded composites.

The ring‐opening polymerization of ɛ‐caprolactone was carried out with poly(ethylene‐co‐vinyl alcohol) as a macroinitiator to synthesize poly(ethylene‐co‐vinyl alcohol)‐graft‐polycaprolactone (EVOH‐g‐PCL). A simple low‐density polyethylene (LDPE)/polycaprolactone (PCL) (64/36) blend lost 5.3 wt % of its original weight after 90 days of a soil burial test. However, the elongation at break of the LDPE/PCL blend remained almost invariable even after the solid burial test because the tensile properties depended mostly on the LDPE phase on account of the poor interaction between the continuous LDPE matrix and the dispersed PCL phase. For EVOH‐g‐PCL, the elongation at break decreased drastically as a result of the soil burial test, and the reduction of the elongation at break was more pronounced for EVOH‐g‐PCL with a higher PCL concentration, even though the weight loss of EVOH‐g‐PCL after the soil burial test was as low as 1.2–1.3% and was nearly independent of the PCL concentration. Few holes were observed in EVOH‐g‐PCL when the PCL concentration was less than 26 wt % after an accelerated hydrolysis experiment at 60°C for 7 days in a 0.1M KOH solution. In contrast, the hydrolysis formed small holes in EVOH‐g‐PCL with a PCL concentration of 36 wt %. The LDPE/PCL blend was much better percolated, as a result of the hydrolysis, than EVOH‐g‐PCL with the same PCL concentration; the soil burial test showed the same results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1064–1071, 2005

Different amounts of glycidyl methacrylate (GMA) were grafted onto corn starch dispersed in water or dimethyl sulfoxide (DMSO) to yield starch‐graft‐poly(glycidyl methacrylate) (ST‐g‐PGMA). ST‐g‐PGMAW, obtained by grafting PGMA onto corn starch that was dispersed in water, showed a higher PGMA grafting content and a lower content of the homopolymerized PGMA than ST‐g‐PGMAD, which was prepared in DMSO. The modified starches were blended with poly(ϵ‐caprolactone) (PCL) and nylon 610, respectively, and the tensile properties of the blends were measured by UTM. Mechanical properties of the biodegradable ST‐g‐PGMA/PCL blends were dependent on the PGMAD content grafted on starch. Without dramatic loss of the tensile properties of PCL, ST‐g‐PGMAW was melt blended with PCL. Meanwhile, an increase in the tensile modulus was observed in the ST‐g‐PGMAW/nylon 610 blend. When nylon 610 was reacted with ST‐g‐PGMAW in DMSO in the presence of triethylamine, the tensile modulus and strength were much higher than those of the pure nylon 610, and phase‐separated domains of starch were not observed microscopically.

Flexible heaters were prepared by extruding platinum‐catalyzed silicone rubber composites with conductive carbon black (CB) and metallic fillers. The conductor resistivity of the extruded heaters decreased in order of conductive titanium dioxide (TiO2) > aluminum powder ≈ zinc powder > copper powder. Thermoelectric switching phenomena were investigated for the silicone rubber/CB/metallic powder systems. The positive temperature coefficient effect was dependent mainly on the CB content rather than on the content of the metallic powders. Resistivity and thermal reproducibility of the extruded heaters were also investigated by periodically applying AC voltage of 110 V. The heaters containing copper and TiO2 powders exhibited excellent electrical reproducibility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1122–1128, 2005

The effect of alloy composition on the glass forming ability (GFA) of the Ca-Zn-Mg alloys has been investigated in the present study. The alloy compositions investigated are near Ca-rich ternary eutectic composition; Ca60Mg15Zn25, Ca65Mg10Zn25, Ca65Mg15Zn20, Ca65Mg20Zn15, and Ca70Mg15Zn15. Bulk metallic glass (BMG) samples with the diameter larger than 5 mm are fabricated by conventional copper mold casting method in air atmosphere. Among the parameters representing the glass forming ability, Trg and γ parameters exhibit good correlation with the maximum diameter of the fully amorphous structure in the alloy compositions investigated in the present study.

Poly(ethylene-co-vinyl acetate) with 55 wt % vinyl acetate units (EVA55) was cryogenically ground and saponified in KOH/ethanol solution to obtain poly(ethylene-co-vinyl alcohol) (EVOH55). Polymeric antimicrobial agents were synthesized by reacting three antimicrobial agents, 4-aminobenzoic acid (ABA), salicylic acid (SA), and 4-hydroxy benzoic acid (HBA) with EVOH55. The polymers became more flexible and exhibited lower melting peak temperature and heat of fusion as the content of the chemically bound ABA, SA, and HBA units increased. These phenomena appeared more significant in the order of ABA < HBA < SA. S. aureus, Gram-positive bacterium, was more susceptible to the polymeric antimicrobial agents than P. aeruginesa, Gram-positive bacterium. The antimicrobial activity increased in the order of EVOH55-HBA < EVOH55-ABA < EVOH-SA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 765–770, 2004

Poly(L-lactide) (PLLA) and poly(3-hydrobutyrate-co-3-hydroxyvalerate) (PHBV) were blended with poly(butadiene-co-acrylonitrile) (NBR). Both PLLA/NBR and PHBV/NBR blends exhibited higher tensile properties as the content of acrylonitrile unit (AN) of NBR increased from 22 to 50 wt %. However, two separate glass transition temperatures (Tg) appeared in PLLA/NBR blends irrespective of the content of NBR, revealing that PLLA was incompatible with NBR. In contrast, a single Tg, which shifted along with the blend composition, was observed for PHBV/NBR50 blends. Moreover NBR50 suppressed the crystallization of PHBV, indicating that PHBV was compatible with NBR50. Decrease of both elongation modulus and stress at maximum load was less significant and increase of elongation at break was more pronounced in PHBV/NBR50 blends than in PLLA/NBR50 blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3508–3513, 2004

Various output heaters were extruded with acetylene black–filled platinum-catalyzed silicone rubber. The resistivity–temperature behavior of extruded heaters exhibited a positive-temperature coefficient (PTC) effect without any negative-temperature coefficient (NTC) effect. Resistivity and thermal reproducibility of the extruded heaters were investigated during heating and cooling cycles at an applied voltage of 220 V. These heaters initially showed poor reproducibility of resistivity during the repeated cycles and this effect increased significantly as the acetylene black content decreased. PTC effect and electrical reproducibility were improved significantly during the thermal ageing process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1611–1617, 2004

Five monomers with azole moieties were synthesized and their antimicrobial activities were investigated. The antimicrobial activity of the monomers was evaluated by the halo zone test method. The results strongly depended on the chemical structure of the group attached to the azole moieties. Polymers with (benzimidazol-2-yl)thio groups and with (5-methyl-1,3,4-thiadiazol-2-yl)thio groups were synthesized. The shake flask test showed that the two polymers possessed excellent antimicrobial activity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2933–2937, 2003

Chain extension of poly(L-lactic acid) (PLLA) with unsaturated groups (PLBM) was attempted using benzoyl peroxide (BPO) and the resulting variation in molecular weight and mechanical properties was explored. Bulk copolymerization of L-lactic acid (LA)/1,4-butanediol (BD)/maleic acid (MA) (100/1/1) isomerized some of the cis-structured maleate units into trans-structured fumarate units. The optically active LA promoted isomerization during the condensation polymerization. Chain extension of PLBM with BPO did not bring about a discernible increase in the molecular weight when the chain extension was carried out in various solvents with different radical abstraction abilities. In contrast, the hot pressing of PLBM containing BPO increased the molecular weight and sometimes produced chloroform-insoluble gels depending on the BPO concentration and temperature. The chain extension at low temperatures increased the flexibility of PLBM considerably. However, PLBM lost the flexibility precipitously as the chain-extension temperature increased above 120°C. The biodegradation rate of PLBM was much slower than that of PLLA. The biodegradation rate was further lowered by the chain extension. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1802–1807, 2003

An acryl monomer containing the quinolone moiety was synthesized and then polymerized with azobisisobutyronitrile in a dimethylformamide solution. The resulting polymer as well as the corresponding monomer exhibited an excellent antibacterial activity. The poly(acrylated quinolone) (PQ) was compounded with other ordinary synthetic polymers such as low-density polyethylene (LDPE), poly(butylene succinate) (PBS), poly(methyl methacrylate) (PMMA), maleated polypropylene (PPMA), and polycaprolactone (PCL). The polymer blends reduced the viable cell number significantly on contact during the shake flask test even when the PQ content was as low as 1 wt %. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1797–1801, 2003

Low density polyethylene (LDPE) was reacted with benzoyl peroxide (BPO) and 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO) to prepare a latent macroinitiator, PE–TEMPO. Little polymer was synthesized when maleic anhydride (MAH) was bulk polymerized in the presence of the PE–TEMPO. However, addition of styrene accelerated the polymerization rate and PE-grafted-poly(styrene-co-maleic anhyride) [PE-g-P(ST-co-MAH)] was produced to a high yield. Chemical reaction between MAH units and hydroxyl groups of starch was nearly undetectable in the PE/PE-g-P(ST-co-MAH)/starch blend system, and the tensile properties of the blend were not enhanced significantly. However, addition of tetrabutyl titanate (TNBT) during the blending procedure improved the tensile properties significantly through an increased interfacial adhesion between the components in the blend system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2434–2438, 2003

Poly(ethylene-co-vinyl acetate) (EVA) powders containing 10 and 20 wt % of vinyl acetate (VAc) units was saponified in ethanol/KOH solution in a heterogeneous manner. Intermolecular interaction between vinyl alcohol(VOH) units in the produced poly(ethylene-co-vinyl alcohol) (EVOH) promoted the crystallization of intervening segments composed of ethylene units. Ring opening polymerization of caprolactone (CL) in the presence of EVOH gave EVOH-g-PCL graft copolymers with relatively short chain branches. Even though the graft copolymerization was carried out in a homogeneous solution, all the VOH units were not equally reactive for the PCL grafting. And the unreacted VOH units decreased very slowly with the graft copolymerization time. EVOH-g-PCL decreased the domain size of the dispersed phase in low density polyethylene (PE)/biodegradable master batch (MB) blends, and thus increased their tensile properties significantly. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2561–2569, 2002