Clover Pattern Research Articles

One-step preparation and dual mode luminescence anti-counterfeiting application of LiYF4: Yb3+, Ho3+, Ce3+@ carbon quantum dot composite materials

In the field of fluorescent anti-counterfeiting, materials with single luminous mode are easy to be forged, which cannot meet the current anti-counterfeiting requirements. Currently reported bimodal light-emitting materials usually require multi-step and tedious synthesis steps. In this paper, LiYF4: Yb3+, Ho3+, Ce3+ upconversion micron particles (UCMPs)/carbon quantum dots (CDs) composite materials were prepared by one-step hydrothermal method, which greatly simplified the composite process of CDs and UCMPs. The upconversion wavelength (from green light to red light excited by 980 nm) can be achieved by changing the doping concentration of Ce3+ ions. Through the combination of CDs and UCMPs, an obvious dual mode luminescence phenomenon was achieved. Finally, screen printing was used to produce a clover pattern, which realized multi-color luminescence under 365 nm and 980 nm excitations respectively. The new fluorescence anti-counterfeiting composites, which uses simple and environmentally friendly one-step synthesis process, is expected to promote the development of fluorescence anti-counterfeiting field.

Design, Synthesis, and Characterization of a Novel Blue-Green Long Afterglow BaYAl3O7:Eu2+, Nd3+ Phosphor and Its Anti-Counterfeiting Application.

Herein, a series of novel long afterglow nanophosphors BaYAl3O7:Eu2+, Nd3+ was synthesized by the combustion method. The investigation encompassed the characterization of X-ray diffraction, morphology, chemical valence, elemental composition, and photoluminescence behavior of BaYAl3O7:Eu2+ and BaYAl3O7:Eu2+, Nd3+ nanoparticles. Under 365 nm excitation, BaYAl3O7:Eu2+ and BaYAl3O7:Eu2+, Nd3+ show emission bands centered at 497 nm and 492 nm, which are attributed to the 4f65d→4f7 transition of Eu2+ ions. The optimal samples of BaYAl3O7:0.03Eu2+ and BaYAl3O7:0.03Eu2+, 0.02Nd3+ have average fluorescence lifetimes of 850 ns and 1149 ns, respectively. The co-doping of Nd3+ ions as the trap centers produced long afterglow luminescence properties, and the afterglow time could reach up to 8 min. Furthermore, the fluorescent powder can be mixed with polyacrylic acid to prepare anti-counterfeiting inks; a clover pattern and snowflake pattern have been successfully printed using screen printing technology, proving its potential application in the field of anti-counterfeiting.

Identifying the alloy structures of germanene grown on Al(111)

While the growth of germanene has been extensively claimed on many substrates, their exact crystal structures remain controversial. Herein, we systematically explore the surface structures of Ge deposition onto the Al(111) surface by theoretical calculations combined with available scanning tunneling microscopy (STM) and low-energy electron diffraction data. We show that the formation of germanene on Al(111) is energetically unfavorable by $ab\phantom{\rule{0.16em}{0ex}}initio$ evolutionary simulations and high-level random-phase approximation calculations, and the two experimental phases are identified as honeycomb alloys ${\mathrm{Al}}_{3}{\mathrm{Ge}}_{3}/\mathrm{Al}(\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{7})$ and ${\mathrm{Al}}_{3}{\mathrm{Ge}}_{4}/\mathrm{Al}(3\ifmmode\times\else\texttimes\fi{}3)$. It is interesting to find a vacancy at the interface of ${\mathrm{Al}}_{3}{\mathrm{Ge}}_{4}/\mathrm{Al}(3\ifmmode\times\else\texttimes\fi{}3)$, which is responsible for the dark clover pattern in STM experiments. Our results clarify the structural controversy of the Ge/Al(111) system and indicate that the fabrication of germanene on Al(111) remains challenging.

Fulgide Derivative-Based Solid-State Reversible Fluorescent Switches for Advanced Optical Memory

Fulgide Derivative-Based Solid-State Reversible Fluorescent Switches for Advanced Optical Memory

Clinical Usefulness of Ultra-short TE MRA for Follow-up Imaging after Cerebral Aneurysm Clipping

The aims of this study were to elucidate signal pattern of cerebral aneurysm clip in brain magnetic resonance angiography (MRA) using non-contrast enhanced ultra-short echo time (UTE) sequence and to explore effective utilization of this novel technique for patients, who underwent cerebral aneurysm clipping. The clip was embedded in homemade phantom and scanned using UTE sequence. We investigated characteristic features of the artifacts derived from the clip. Besides, we compared the volume of signal loss between conventional time-of-flight (TOF) and UTE-MRA in 50 patients with the cerebral aneurysm clip. In phantom study, the clip was delineated as signal void area fully surrounded by high signal on original images. On reconstructed short-axial views for the clip, four-leaf clover pattern of artifact was observed when clip was arranged orthogonal to the static magnetic field. On the other hand, this artifact disappeared when the clip was arranged in parallel with the static magnetic field. The volume of signal loss in clinical cases was significantly reduced in UTE-MRA (P < 0.05): 1.30, 0.52-2.77 cm3 for TOF; 0.84, 0.28-1.74 cm3 for UTE (median, range). The scan time for UTE-MRA was 2 minutes and 52 seconds. To understand the characteristic feature of the artifacts from the clip could contribute to define vascular structure in image interpretation. Adding UTE-MRA to routine protocol is useful approach for follow-up imaging after cerebral aneurysm clipping with clinically acceptable prolongation of the scan time.

Validation of the Omni: A Novel, Multimodality, and Longitudinal Surgical Skills Assessment

The breadth of technical skills included in general surgery training continues to expand. The current competency-based training model requires assessment tools to measure acquisition, learning, and mastery of technical skill longitudinally in a reliable and valid manner. This study describes a novel skills assessment tool, the Omni, which evaluates performance in a broad range of skills over time. The 5 Omni tasks, consisting of open bowel anastomosis, knot tying, laparoscopic clover pattern cut, robotic needle drive, and endoscopic bubble pop, were developed by general surgery faculty. Component performance metrics assessed speed, accuracy, and quality, which were scaled into an overall score ranging from 0 to 10 for each task. For each task, ANOVAs with Scheffé's post hoc comparisons and Pearson's chi-squared tests compared performance between 6 resident cohorts (clinical years (CY1-5) and research fellows (RF)). Paired samples t-tests evaluated changes in performance across academic years. Cronbach's alpha coefficient determined the internal consistency of the Omni as an overall assessment. The Omni was developed by the Department of Surgery at Duke University. Annual assessment and this research study took place in the Surgical Education and Activities Lab. All active general surgery residents in 2 consecutive academic years spanning 2015 to 2017. A total of 62 general surgery residents completed the Omni and 39 (67.2%) of those residents completed the assessment in 2 consecutive years. Based on data from all residents' first assessment, statistically significant differences (p < 0.05) were observed among CY cohorts for bowel anastomosis, robotic, and laparoscopic task metrics. By pair-wise comparisons, mean bowel anastomosis scores distinguished CY1 from CY3-5 and CY2 from CY5. Mean robotic scores distinguished CY1 from RF, and mean laparoscopic scores distinguished CY1 from RF, CY3, and CY5 in addition to CY2 from CY3. Mean scores in performance on the knot tying and endoscopic tasks were not significantly different. Statistically significant improvement in mean scores was observed for all tasks from year 1 to year 2 (all p < 0.02). The internal consistency analysis revealed an alpha coefficient of 0.656. The Omni is a novel composite assessment tool for surgical technical skill that utilizes objective measures and scoring algorithms to evaluate performance. In this pilot study, 3 tasks demonstrated discriminative ability of performance by CY, and all 5 tasks demonstrated construct validity by showing longitudinal improvement in performance. Additionally, the Omni has adequate internal consistency for a formative assessment. These results suggest the Omni holds promise for the evaluation of resident technical skill and early identification of outliers requiring intervention.

Variable temperature studies on mesogenic polythiophenes using 2D-IR and WAXS

We synthesized and investigated the molecular ordering of 4-{(E)-[(4-alkoxy phenyl imino] methyl} phenyl] thiophene-3-carboxylate (APTC) oligomers of varying alkoxy chain lengths using polarised Infrared spectroscopy (IR) and wide-angle X-ray scattering (WAXS). Infrared polarisation study shows maximum dichroic ratio for Phenyl CC stretching for Decyloxy (PDPTC) at room temperature. During heating C–O–C shows higher dichroic ratio in dodcecyloxy (PDDPTC) due to the restrains in the torsional angle and hindered rotation of it. By using temperature as perturbation, IR correlation (2D-IR) was performed. 2D-IR analysis results are classified into three parts. First, at phase temperature, CO splits into two peaks due to dipole–dipole interaction; second, chain bending in CH2 alkyl chain and variation in CH2 stretching with molecular environment and third, thiophene out of plane bending vibration shows main chain thiophene flipping with respect to alkoxy chain length. In addition to that, an intriguing evidence of liquid crystalline phase stability by CO dipole moment over alkyl chain is seen. 2D-IR analysis of thiophene region also shows “four-leaf clover pattern” on increasing alkoxy chain length and a change in phenyl group C–H in plane bending vibration along with it is evidenced. Hetero correlation between WAXS and IR shows interlayer packing variation with zigzag alignment for lower homologues and linear alignment for higher homologues with lower ‘d’ spacing value plotting with change in CH2 stretching vibration of alkoxy chain length.

861 EXTERNAL VALIDITY OF STANDARDIZED TASKS FOR EVALUATION AND TEACHING OF ROBOTIC TECHNICAL SKILLS

You have accessJournal of UrologyTechnology & Instruments: Surgical Education & Skills Assessment/Ureteroscopy I1 Apr 2012861 EXTERNAL VALIDITY OF STANDARDIZED TASKS FOR EVALUATION AND TEACHING OF ROBOTIC TECHNICAL SKILLS Alvin Goh, Andrew Hung, Isuru Jayaratna, Kara Teruya, Mukul Patil, Matthew Dunn, and Inderbir Gill Alvin GohAlvin Goh Los Angeles, CA More articles by this author , Andrew HungAndrew Hung Los Angeles, CA More articles by this author , Isuru JayaratnaIsuru Jayaratna Los Angeles, CA More articles by this author , Kara TeruyaKara Teruya Los Angeles, CA More articles by this author , Mukul PatilMukul Patil Los Angeles, CA More articles by this author , Matthew DunnMatthew Dunn Los Angeles, CA More articles by this author , and Inderbir GillInderbir Gill Los Angeles, CA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.954AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES There is a growing need for primary acquisition of technical skills to occur outside the operating room. Building on initial validation, we demonstrate external face and construct validity of a standardized model of structured training tasks designed to measure robotic skills called the Fundamentals of Robotic Surgery (FRS). METHODS A broad sample of 49 subjects from various geographic regions, including 11 expert robotic surgeons (completed >30 robotic cases) and 38 urology trainees (ranging from post-graduate year 3 to 8) were evaluated. Standardized instructions and video demonstration were given to each subject. Participant performance of 4 structured robotic tasks (horizontal mattress suture, clover pattern resection, 3-dimensional peg placement, circular target needle placement) was measured using a scoring system based on efficiency and precision. To assess face and content validity, subjects were asked to rate the curriculum on a 5-point Likert scale according to 1) difficulty, 2) similarity to skills required for robotic surgery, 3) usefulness for skills evaluation, 4) usefulness in skills training, and 5) requirement for proficiency. RESULTS Experts consistently performed better than trainees in all 4 tasks of FRS (Table 1). Experts and novices agreed FRS was appropriately challenging and incorporated skills required for robotic surgery (p>0.05). Greater than 96% of respondents thought the structured tasks were useful for robotic skills assessment and training. Table 1. Mean task performance scores (lower is better) Task 1 Task 2 Task 3 Task 4 Experts (n=11) 153±38 147±34 87±22 167±53 Novices (n=38) 265±64 189±67 203±71 315±91 p-value <0.001 <0.001 <0.001 <0.001 CONCLUSIONS We confirm external face, content, and construct validity of a structured inanimate robotic skills curriculum (FRS) in a diverse cohort. Performance on FRS appears to correlate with level of robotic technical ability. This model may be integrated in a comprehensive robotics training program. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e351 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Alvin Goh Los Angeles, CA More articles by this author Andrew Hung Los Angeles, CA More articles by this author Isuru Jayaratna Los Angeles, CA More articles by this author Kara Teruya Los Angeles, CA More articles by this author Mukul Patil Los Angeles, CA More articles by this author Matthew Dunn Los Angeles, CA More articles by this author Inderbir Gill Los Angeles, CA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Phase Separation of Several Kinds of Polyethylene Solution under the Gelation/Crystallization Process

The gelation mechanism of polyethylene solutions was investigated by using light scattering and X-ray diffraction techniques in terms of the liquid-liquid phase separation. Three kinds of polyethylene, ultrahigh molecular weight polyethylene (UHMWPE), low molecular weight linear polyethylene (L-LMWPE), and low molecular weight branched polyethylene (B-LMWPE), were used as test specimens. When an incident beam of He-Ne gas laser was directed to the UHMWPE and B-LMWPE solutions quenched to a desired temperature, the logarithm of scattered intensity increased linearly in the initial stage and tended to deviate from this linear relationship in the latter stage. If the linear increase in the initial stage can be analyzed within the framework of the linear theory of spinodal decomposition proposed by Cahn, the gelation is obviously attributed to the phase separation leading to the concentration fluctuation of the solution. Furthermore, in the later stage showing the deviation from the linear relationship, light scattering from the UHMWPE solution with 0.5% concentration under Hv polarization condition showed an X-type pattern, indicating the appearance of optically anisotropic rods. On the other hand, the scattering from the B-LMWPE solution with 3% concentration showed a four-leaf clover pattern, indicating the appearance of optically anisotropic spherulites. No crystallite was confirmed by the X-ray diffraction measurements, when the rods and spherulites appeared. With further lapse of time, the Hv patterns became clearer and the corresponding X-ray diffraction intensity curves showed a very small diffraction peak from the (110) plane. In contrast, for the L-LMWPE solutions, the logarithm of scattered intensity against time showed a rapid increase and tended to level off because of rapid change from slightly transparent to whiten gels. In such a process, any quantitative analysis of the scattered light intensity was impossible. The corresponding X-ray diffraction revealed the strong reflections from the (110) and (200) planes, indicating the rapid formation of stable crystallites. Through a series of experiments for the three kinds of polyethylene solution, it turned out that gelation mechanism of polyethylene solutions is strongly affected by molecular weight and the degree of branching.

Time-Evolution of Polymer Spherulite Formation Investigated by Light Scattering

The time-evolution of polymer spherulite formation in the melt was investigated by H V light scattering. The H V scattering gives both the 'four-leaf clover pattern' and isotropic scattering independent of azimuthal angle. The isotropic scattering from spherulites of isotactic polystyrene is measured over a wide range of crystallization: from bundles to a matured spherulite. Correlation length is obtained from the isotropic scattering. In the early stage of spherulite growth, the correlation length increases in proportion to crystallization time and reaches maximum value of about 1 μm. Hence, the isotropic scattering is attributed to the bundles. The correlation length is the size of the bundles. The bundles grow and successively evolve to spherulites by branching. In the late stage, a matured spherulite grows. However, the correlation length decreases to a value of about 0.6μm and remains unchanged. By re-examination of the lattice model of Yoon and Stein, the model is found applicable to matured spherulites. The correlation length in matured spherulites is suggested to be the distance between branches of a bundle. The length agrees to a distance between screw dislocations in a crystal grown from the polymer melt.

Vortex Formation in Ellipsoidal Thermal Bubbles

The rise of an isolated dry thermal bubble in a quiescent unstratified environment is a prototypical natural convective flow. This study considers the rise of an isolated dry thermal bubble of ellipsoidal shape (elliptical in both horizontal and vertical cross sections). The azimuthal asymmetry of the bubble allows the vorticity tilting mechanism to operate without an environmental wind. The dry Boussinesq equations of motion are solved analytically as a Taylor series in time for the early time behavior of the bubble (involving derivatives of up to the third order in time). The analytic results are supplemented with numerical simulations to examine the longertime behavior. The first nonzero term in the Taylor expansion for the vertical vorticity is a third-order term, and appears as a four-leaf clover pattern with lobes of alternating sign. The horizontal flow associated with this vorticity pattern first appears as a sheared stagnation point-type flow, but eventually organizes into vertical vortices that fill the bubble. The vortices induce large structural changes to the bubble and eventually reverse the sense of the azimuthal asymmetry. 1. Introduction and background Natural (free) convective flows abound in nature and technology. Examples include flows induced by lit cigarettes, computer CPUs, electronic circuitry, radiator fins, charcoal grills, and the heated ground. The structure of the convective atmospheric boundary layer is dependent, in part, on the statistical structure of individual and mutually interacting convective elements, and on the interactions between convective elements and the environmental wind. Many of these and other natural convective flows are azimuthally asymmetric. However, because even the most idealized natural convective entities are intrinsically nonlinear (fluid inertia and the coupling between dynamical and thermodynamical variables are essential aspects of the problem), they have been difficult to analyze theoretically without considering their ensemble characteristics to be axisymmetric or slab-symmetric. The present study is one of the first to focus on the impact of asymmetrical geometry (ellipticity in both horizontal and vertical cross sections) on the behavior of an isolated thermal bubble. The azimuthal ellipticity allows the vorticity tilting mechanism to operate even in the absence of wind shear. The subsequent development of vertical vortices and associated

Adipose body of the orbit.

The adipose body of the orbit (ABO) fills most of the orbital cavity, surrounding the eyeball, muscles, nerves, and vessels. It was studied in histologic section in the three basic planes in the fetus, neonate, and adult. In the retrobulbar area, that is, posterior to the eyeball, adipose tissue occupies the space around the optic nerve and penetrates between the recti muscles, describing a four-leafed clover pattern in frontal section. The fatty tissue of the retrobulbar area also includes the peripheral ring of fat that lies between the muscles and the walls of the orbit. In the part of the peribulbar area located between the muscular insertions on the eyeball anteriorly and the emergence of the optic nerve from the sclera posteriorly, the pattern of adipose tissue is identical to the peripheral ring of fat and the fat between the muscles in the retrobulbar area. External to the muscular insertions and the anterior part of the eyeball, there is a thin ring of histologically similar fatty tissue that is continuous anteriorly with the fatty bodies of the upper and lower eyelids. Histologic examination shows that the lobules are large in that part of the retrobulbar area within the muscle cone and that they are smaller with more fibrous septa in the remaining restricted regions, such as the area between the eyeball and muscles and in the rings around the muscles and around the eyeball. In no case was a septum found separating the peripheral adipose ring from the fat located within the muscle cone.

Liquid phase behavior and its effect on crystalline morphology in the extruded poly(ethylene terephthalate)/poly(ethylene-2,6-naphthalate) blend

Morphology in an extruded poly(ethylene terephthalate)/poly(ethylene-2,6-naphthalate) was investigated using time-resolved light scattering, optical microscope and small-angle X-ray scattering. During annealing at 280 °C, the domain structure via spinodal decomposition preceded, the transesterification followed, and then the transesterification between the two polyesters induced the dissolution of the liquid–liquid (L–L) phase separation, i.e. the homogenization. The annealed specimen for various time periods ( t s) at 280 °C was subjected to a temperature-drop to 120 °C for the isothermal crystallization and then the effects of liquid phase morphology on crystallization was investigated. With t s, the H ν (cross-polarization) light scattering patterns exhibited the dramatic change from a four-leaf clover pattern with maximum intensity at azimuthal angle 45° (×-type scattering pattern) to a diffuse pattern of circular symmetry and then a four-leaf clover pattern with maximum intensity at azimuthal angles 0 and 90° (+-type scattering pattern). This suggests that the crystalline structure depends on the level of the block and/or random copolymer produced by the transesterification during annealing. The H ν scattering patterns reflected differences in the principle polarizability of the crystalline lamellae with respect to the spherulitic radius. On the other hand, the long period L B, an average distance between two adjacent crystalline lamellae, increased with t s at 280 °C. The dependence of L B on t s was explained by the change in the crystallization rate G.

Polysulfide containing s-triazine rings as a new thermoplastic elastomer: Spherulite morphology arid strain recovery behaviour

A new polymer, polysulfide containing s -triazine rings, was found to be crystalline but it showed an excellent strain recovery after large deformation; residual strain was less than 10% after 25–400% elongation. The elastic recovery was much better than low density polyethylene (LDPE), a typical rubber-like crystalline polymer. As in the case of LDPE, a four-leaf clover pattern in H v (cross-polarized) light scattering was observed, suggesting the formation of spherulites. The H v pattern deformed with bulk deformation and recovered to the original pattern after releasing, without any change in the disorder parameter of orientation correlation. The reversible change in scattering pattern suggests that the spherulite itself is highly elastic and it may render the elastomeric character in bulk.

Deformation mechanism of polyethylene spherulites estimated by crystal orientation distribution function and small angle light scattering under Hv polarization condition

The deformation mechanism of polyethylene spherulites was studied by using melt films of high density polyethylene with a 78% crystallinity in terms of crystallite orientation distribution estimated by X-ray diffraction technique and small angle light scattering under Hv polarization condition. In doing so, a model relating crystal orientation to the deformation of polyethylene spherulite was proposed. The distribution function of crystallites within a spherulite was assumed to be a function of crystal lamella. The distribution functions of reciprocal lattice vectors of given crystal planes were derived from two functions of the crystallites and lamellae with several parameters. The best values of each parameter were determined by the simplex method associated with direct research method to obtain the object function on the basis of trial and error. As a result, it was found that at an initial elongation ratio of 1.5, the most important factor in fitting the model to experimental results, was the preferred orientation of lamellar axis but most of the crystallites within the lamella were maintained without taking characteristic orientation. The Hv scattering from a deformed three-dimensional spherulite was formulated on the basis of the proposed model. The scattered intensity distribution in an undeformed state showed the typical four-leaf clover pattern and the lobes extending in the horizontal direction indicated the deformation of spherical to ellipsoid structure with a draw ratio of 1.5. The calculated patterns were in good agreement with those observed.

A light scattering study on films of a nematic main chain thermotropic liquid crystalline polymer

The morphology of a cast thin film of a thermotropic main chain polyester was studied using optical microscopy and small angle light scattering (SALS). It was found that the SALS pattern arising from the nematic texture is a four-leaf clover pattern where the lobes are oriented at 0° and 90°. The characteristic dimension associated with this pattern follows the coarsening of the texture upon annealing, thus providing a means of monitoring morphology changes in the film. Using this means it was possible to investigate the kinetics of texture evolution from the isotropic state to the final equilibrium nematic texture. It was found to be very fast. It was also found that the characteristic dimension associated with the pattern depends strongly on film thickness.

Small‐angle scattering of polarized light. I. comparison of theoretical predictions for isotropic and anisotropic spheres

AbstractThis paper describes small angle light scattering (SALS) calculations and compares the results for isotropic and anisotropic spheres. For isotropic spheres the exact Mie theory is compared with the Rayleigh‐Gans‐Debye (RGD) and the anomalous diffraction (AD) approximations in order to study the validity of the approximations. For anisotropic spheres the RGD is compared with the AD approximation. A study of SALS in the RGD approximation shows that the first‐order intensity maximum corresponding to a lobe of the four‐leaf clover pattern is not only a function of the sphere diameter but also depends on the isotropic and the anisotropic refractive index of the sphere. The practical implications of this are discussed.

Crystal orientation in a semicrystalline polymer in relation to deformation of polymer spherulites. III. Small‐angle light scattering

AbstractSmall‐angle polarized light scattering from a deformed three‐dimensional spherulite is formulated on the basis of the deformation model proposed in Part II of this series. The intensity distribution of scattered light is discussed chiefly for the cross‐polarization condition, the so‐called Hv polarization, as a function of elongation of the spherulite. In the undeformed state, the scattered intensity distribution forms the typical fourleaf clover pattern, and the intensity decreases with increasing fraction of crystals oriented randomly (type R crystals) within the crystal lamellae of the spherulites. In a system composed of type R crystals and folded‐chain crystals (type B crystals) within the lamellae, the four‐leaf pattern moves to the horizontal zone near the equator with increasing elongation of the spherulite, and, simultaneously, extends to some extent to the vertical zone near the meridional direction as a parameter measuring the ease of lamellar untwisting increases. In a system composed, in addition to type R and type B crystals, of crystals transformed from type B to type Ca and type Cr due to tilting and unfolding of polymer chains, respectively, within the crystal lamellae an eight‐leaf pattern appears, even at small elongation up to about 30%. Each lobe of the eight‐leaf pattern undergoes a characteristic change with increasing elongation. In both systems, the scattered intensity increases with sharpening of orientation distribution of crystals within the crystal lamellae.

Light-Scattering Patterns from Polyethylene Films in Relation to Spherulitic Crystalline Texture

Hv Light-scattering patterns from film specimens of relatively low density polyethylenes differ from the so-called “four leaf clover pattern” which is often found in the case of a well-grown spherulitic texture of polyethylene and can be derived from Stein’s formulation of the scattered pattern. The pattern is some modifications removed from the “four leaf clover” pattern so as to have a rather long leafstalk, and may be called “four tennis rackets” arranged orthogonally.Some modifications of Stein’s formulation for an isolated spherulite of a rather simple and regular anisotropy are proposed by taking the distribution of the size of spherulites into account, taking the spherulite anisotropy, (αr−αt), as a function of distance from the center of the spherulite, and further making the boundary of the spherulite less clear.The former two modifications do not give any essential change in the scattering pattern from that predicted by the Stein’s formulation, except for some shifts of the scattering angle at maximum intensity, while the latter modification gives the extension of the logarithmic contour plot of scattered intensity to lower scattering angles, and confirms the pattern of the “four tennis rackets.”In addition, a modification of the spherulitic crystalline texture to a sheaf-like texture by using a two-dimensional symmetric sector model also gives an extension of the logarithmic contour plot to lower scattering angles, even showing the strongest scattered intensity at the lower angles when the sector angle is taken as less than 50°.