Fan-like Structure Research Articles

Properties and Function of the Medial Patellofemoral Ligament: A Systematic Review

Background: As the main passive structure preventing patellar lateral subluxation, accurate knowledge of the anatomy, material properties, and functional behavior of the medial patellofemoral ligament (MPFL) is critical for improving its reconstruction. Purpose: To provide a state-of-the-art understanding of the properties and function of the MPFL by undertaking a systematic review and statistical analysis of the literature. Study Design: Systematic review. Methods: On June 26, 2018, data for this systematic review were obtained by searching PubMed and Scopus. Articles containing numerical information regarding the anatomy, mechanical properties, and/or functional behavior of the MPFL that met the inclusion criteria were reviewed, recorded, and statistically evaluated. Results: A total of 55 articles met the inclusion criteria for this review. The MPFL presented as a fanlike structure spanning from the medial femoral epicondyle to the medial border of the patella. The reported data indicated ultimate failure loads from 72 N to 208 N, ultimate failure elongation from 8.4 mm to 26 mm, and stiffness values from 8.0 N/mm to 42.5 N/mm. In both cadaveric and in vivo studies, the average elongation pattern demonstrated close to isometric behavior of the ligament in the first 50° to 60° of knee flexion, followed by progressive shortening into deep flexion. Kinematic data suggested clear lateralization of the patella in the MPFL-deficient knee during early knee flexion under simulated muscle forces. Conclusion: A lack of knowledge regarding the morphology and attachment sites of the MPFL remains. The reported mechanical properties also lack consistency, thus requiring further investigations. However, the results regarding patellar tracking confirm that the lack of an MPFL leads to lateralization of the patella, followed by delayed engagement of the trochlear groove, plausibly leading to an increased risk of patellar dislocations. The observed isometric behavior up to 60° of knee flexion plausibly suggests that reconstruction of the ligament can occur at flexion angles below 60°, including the 30° and 60° range as recommended in previous studies.

Size-selected anion photoelectron spectroscopy and density functional theory study of MnCn -/0 (n = 3-10): Odd-even alternation and linear-cyclic structure competition.

The structural and electronic properties of MnCn - (n = 3-10) clusters have been investigated using size-selected photoelectron spectroscopy and density functional theory calculations. The vertical detachment energies of MnCn - exhibit a strong odd-even alternation with increasing number of carbon atoms: the vertical detachment energies of MnCn - containing even number of carbon atoms are higher than those of adjacent ones containing odd number of carbon atoms. The theoretical analyses indicate that the spin multiplicities and relative stabilities of MnCn -/0 also exhibit odd-even alternations. It is found that MnC3 - has three degenerate isomers with two linear structures in different electronic states and one fanlike structure. For n = 4-6, 8, and 10, the ground state structures are all linear with the Mn atom at one end. MnC7 - and MnC9 - have cyclic structures. As for the neutral species, MnC3 and MnC4 adopt fan-shaped structures, MnC5 has a linear structure, and MnC6-10 have cyclic configurations. The atomic dipole moment corrected Hirshfeld population analysis shows that the electrons transfer from the Mn atom to the Cn units. The total spin magnetic moments of MnCn -/0 (n = 3-10) clusters are mainly contributed by the local magnetic moments on the Mn atom.

Spontaneous and induced magnetic phase transitions in Tb0.9Er0.1Ni5

Abstract Magnetic and neutron powder diffraction measurements have been carried out on Tb0.9Er0.1Ni5 intermetallic compound. The intermetallide crystallizes in the hexagonal CaCu5-type structure and possesses a long-range magnetic order at temperatures below 22 K. A fan-like magnetic structure is described by two propagation vectors: k1 = 0 and k2 = 2π/c(0, 0, 0.036), at 20 K. The total Tb-ion magnetic moment has the ferromagnetic and modulated components. The latter is a transverse spin wave. When the sample is cooled at a temperature below 8 K, the module of the k2 vector does not change and is equal to k2 = 2π/c(0, 0, 0.027). An “incommensurate – lock-in” magnetic transition takes place at 8 K. The k2 vector exhibits a temperature hysteresis of about (5–6) K, whereas the intensities of Bragg reflections and satellites do not show up appreciable changes. When an external magnetic field is applied to the sample, the satellites and the module of the k2 vector decrease, while the Bragg intensities increase. The sample becomes a ferromagnetic at a field of ∼2 kOe, and the Tb-ion magnetic moment is equal to 8.3 μB. A general notion of the Tb0.9Er0.1Ni5 magnetic state evolution with an external field is given using the field dependence of the background intensity in diffraction patterns. First principle calculations for TbNi5 and Tb0.9Er0.1Ni5 are performed including the 4f states into the orbital basis and accounting for strong electronic correlations and spin-orbital coupling. This allowed obtaining both spin and orbital moments of the effective Tb-ion moment and estimating also the value of Tb-Tb exchange interaction.

The anatomy of the male inferior hypogastric plexus: What should we know for nerve sparing surgery.

The aim of this study was to investigate the nerve supply to the structures in the male lesser pelvis and review its clinical relevance, especially during nerve sparing surgery. Three formalin-embalmed and 16 Thiel-embalmed male hemipelves were used. They were microdissected after repeated treatments with nitric acid diluted 1:10 with milliQ-water. The inferior hypogastric plexus (IHP) is a fan-like structure lateral from the rectum on the fascia of the levator ani. Nerves emerging from the proximal, solid part of the plexus follow the internal iliacal vessels and reach the prostate from dorsolateral. The innervation of the urethra and the corpora cavernosa derives from two origins: one follows the ejaculatory duct and the seminal vesicle, reaching the proximal urethra and the prostate from dorsal; the other follows the inferior vesical artery to reach the prostate from lateral, and then forms the neurovascular bundle on both sides of the prostatic fascia, spreading to the pelvic floor muscles and the corpora cavernosa along with the distal urethra. A connection between the two parts was demonstrated in approximately one third of the samples investigated. The nerve supply to the urinary bladder, the urethra, and the corpora cavernosa emerges mainly from the IHP. The innervation of the proximal urethra and its autonomic muscular structures has a dorsal (ejaculatory duct) and lateral (inferior vesical artery) origin. To maintain good erectile and continence function it is important to save both the dorsal and lateral neurovascular roots. Clin. Anat. 31:788-796, 2018. © 2018 Wiley Periodicals, Inc.

Formation of twinned dendrites during unidirectional solidification of Al-32%Zn alloy

Abstract The present study focused on the formation and crystallographic orientation of twinned dendrites coexisting with equiaxed grains in unidirectional solidification of Al-32%Zn (mass fraction) alloy. The morphology was investigated by optical metallograph and electron back-scattered diffraction technique. Results showed that the macrostructure of the alloy exhibited a typical feathery and fan-like structure while the microstructures were elongated lamellas, which were separated by coherent and incoherent twin boundaries. Both the primary trunk and all lateral arms of twinned dendrites grew along 〈110〉 directions, unlike regular 〈100〉 α(Al) dendrites. The facet growth of crystals at solid/liquid interface was responsible for the origin of twinned dendrites during the weak local convection, and high thermal gradient and medium solidification velocity had significant contribution to the formation of twinned dendrites. The formation mechanism of twinned dendrites which consisted of three multiplication ways of new twin boundaries formation and one way of dendrite evolution in twin plane was shown schematically.

Inspissated cyst fluid in endoscopic ultrasound-guided fine needle aspiration of pancreatic cysts.

Inspissated cyst fluid may be identified on pancreatic cyst aspiration cytology. We report on the cytomorphologic characteristics of inspissated cyst fluid on EUS-FNA of pancreatic cysts and correlate this finding with histopathology or multimodal (cytology, cyst fluid analysis, molecular pathology, imaging) classification of cyst type. The department archives were searched for pancreatic cyst fine-needle aspiration biopsies that contained dessicated, crystalline or inspissated material on cytologic preparations. Twenty-eight cases of pancreatic cysts containing inspissated material were identified. The cytomorphology of the inspissated material ranged from fibrillary fan-like structure (54%), ball-like structures (57%), and granular material (43%). When present, the fibrillary inspissated material was associated with neoplastic mucinous cysts in 11/15 (73%) cases, but was also seen in 2 pseudocysts, 1 serous cystadenoma, and 1 cyst of uncertain type (suggestive of mucinous cyst on EUS). The presence of fibrillary inspissated cyst material on cytology had a positive predictive value of 79% and a specificity of 63% for a neoplastic mucinous cyst. Although not highly specific, the presence of inspissated cyst fluid with fibrillary architecture should be recognized by cytopathologists and interpreted as at least "atypical" given the potential association with neoplastic mucinous cysts of the pancreas.

Organic superalkalis with closed-shell structure and aromaticity

ABSTRACTBenzene (C6H6) and polycyclic hydrocarbons such as naphthalene (C10H8), anthracene (C14H10) and coronene (C24H12) are well known aromatic organic compounds. We study the substitution of Li replacing all H-atoms in these hydrocarbons using density functional method. The vertical ionisation energy of such lithiated species, i.e. C6Li6, C10Li8, C14Li10 and C24Li12 ranges 4.24–4.50 eV, which is lower than the ionisation energy (IE) of Li atom. Thus, these species may behave as superalkalis due to their lower IE than alkali metal. However, these lithiated species possess planar and closed-shell structure, unlike typical superalkalis. Furthermore, all Li-substituted species are aromatic although their degree of aromaticity is reduced as compared to corresponding hydrocarbon analogues. We have further explored the structure of C6Li6 as star-like, unlike its inorganic analogue B3N3Li6, which appears as fan-like structure. We have also demonstrated that the interaction of C6Li6 with a superhalogen (such as BF4) is similar to that of a typical superalkali (such as OLi3). This may further suggest that the proposed lithiated species may form a new class of closed-shell organic superalkalis with aromaticity.

Chemical evolution of alkali–silicate reaction (ASR) products: a Raman spectroscopic investigation

The objective of this study was to use Raman spectroscopy to study the morphology and chemical changes of alkali–silicate reaction (ASR) products over time. The reaction products induced by ASR on soda-lime glass slides in a high temperature alkaline environment (1 N NaOH at 80 °C) enriched with calcium hydroxide were studied at 0, 1, 4, 7, 14 and 28 days. The results show that the morphology of the granular-like and fan-like fascicles structure that formed at early ages was more ordered in terms of polymerization and dominated by Q3 and Q2 units. This information implies that the ASR products were probably of mainly alkali silica composition with low content of calcium in the structure. As the reaction proceeded the products depolymerized, forming a cloud-like morphology of decreased structural order which surrounded the initial product particles. It can be hypothesized that more calcium ions in the soak solution entered into the particle structure, promoting a depolymerization and possible formation of a C–S–H phase which was indicated by the dominant presence of Q1 units after 7 days of exposure. To corroborate the interpretation of Raman spectra, 28-day ASR products were verified by Fourier transform infrared.

Magnetic structure and magnetization of helical antiferromagnets in high magnetic fields perpendicular to the helix axis at zero temperature

The zero-temperature angles of magnetic moments in a helix or sinusoidal fan confined to the xy plane, with respect to an in-plane magnetic field Hx applied perpendicular to the z axis of a helix or fan, are calculated for commensurate helices and fans with field-independent turn angles kd between moments in adjacent layers of the helix or fan using the classical J0-J1-J2 Heisenberg model. For 0 < kd < $4\pi/9$, first-order transitions from helix to a fan structure occur at fields Ht as previously inferred, where the fan is found to be approximately sinusoidal. However, for $4 \pi/9$ < kd < $\pi$, different behaviors are found depending on the value of kd and these properties vary nonmonotonically with kd. In this kd range, the change from helix to fanlike structure is usually a crossover with no phase transition between them, although first-order and second order transitions are found. We also calculated the average x-axis moment per spin $\mu_{x ave}$ versus Hx for helices and fans with crossovers and phase transitions between them. When smooth helix to fanlike crossovers occur in the range $4\pi/9$ < kd < $\pi$, $\mu_{x ave}$ exhibits an S-shape behavior with increasing Hx. This predicted behavior is consistent with $\mu_{x ave}$(Hx) data previously reported by Sangeetha, et al. [Phys. Rev. B 94, 014422 (2016)] for single-crystal EuCo2P2 possessing a helix ground state with kd = $0.85\pi$. The low-field magnetic susceptibility and the ratio Ht/Hc are calculated analytically or numerically versus kd for helices.

Modelling the mechanical structure of extreme shear ruptures with friction approaching zero generated in brittle materials

Experiments on frictional stick-slip instability in brittle materials and natural observations show that friction falls towards zero in the head of shear ruptures propagating with extreme velocities (up to supershear levels). Although essential for understanding earthquakes, fracture mechanics and tribology the question of what physical processes determine how weakening occurs is still unclear. Here, using a mathematical model, we demonstrate that the extremely low friction can be caused by a fan-like fault structure formed on the basis of a tensile-cracking process observed in all extreme ruptures. The mathematical model visualises and describes the fan-structure as a mechanical system during rupture propagation. It explains some features observed in laboratory experiments.

Transformation Mechanism of (γ + γ′) and the Effect of Cooling Rate on the Final Solidification of U720Li Alloy

The transformation mechanism of (γ + γ′) was studied by analyzing the microstructure and elemental distribution of the U720Li samples heated at 1250 °C and cooled at the rates in the range of 1–100 °C/s. Although the (γ + γ′) is deemed to be formed by a eutectic reaction and has been called eutectic (γ + γ′), it was found in the present study that the (γ + γ′) precipitation begins with a peritectic reaction of (L + γ) → γ′, and develops by the eutectic reaction of L → (γ + γ′). The energy for the γ′ nucleation is low because the interfacial energy for the γ/γ′ interface is about one-tenth of the solid/liquid interface, and hence, the nucleation rate is high and the fine structure of (γ + γ′) is formed at the initial precipitation stage. The γ and γ′ in (γ + γ′) tend to grow into a lamellar structure because it is difficult for them to nucleate directly from the residual liquids, and hence, the γ′ precipitates naturally tend to grow divergently direction of the regions rich in Al and Ti, forming a fan-like structure of the (γ + γ′). As a result, the γ′ precipitates will coarsen finally because the space between them is enlarged. The solidification of the final residual liquids is a diffusion dependent process. When cooled at a higher rate, a higher degree of super cooling is reached and finally the solidification is finished by the pseudo-eutectic reaction of L → (γ + boride) and L → (γ + η), which can absorb Zr and B. When cooled at a rate low enough, most of the residual liquids are consumed by the (γ + γ′) growth due to the sufficient diffusion, and the boride and Zr-bearing phase are precipitated at a quasi-equilibrium state. Under this condition, Ti is depleted at the (γ + γ′) growth front. However, the η-Ni3Ti phase is formed there occasionally due to the boride precipitation, because the compositions of the two phases are complementary.

CUSP-SHAPED STRUCTURE OF A JET OBSERVED BY IRIS AND SDO

ABSTRACT On 2014 August 29, the trigger and evolution of a cusp-shaped jet were captured in detail at 1330 Å by the Interface Region Imaging Spectrograph. At first, two neighboring mini-prominences arose in turn from the low solar atmosphere and collided with a loop-like system over them. The collisions between the loop-like system and the mini-prominences lead to the blowout, and then a cusp-shaped jet formed with a spire and an arch-base. In the spire, many brightening blobs originating from the junction between the spire and the arch-base moved upward in a rotating manner and then in a straight line in the late phase of the jet. In the arch-base, dark and bright material simultaneously tracked in a fan-like structure, and the majority of the material moved along the fan's threads. At the later phase of the jet's evolution, bidirectional flows emptied the arch-base, while downflows emptied the spire, thus making the jet entirely vanish. The extremely detailed observations in this study shed new light on how magnetic reconnection alters the inner topological structure of a jet and provides a beneficial complement for understanding current jet models.

Variation in Display Behavior, Ornament Morphology, Sexual Size Dimorphism, and Habitat Structure in the Fan-Throated Lizard (Sitana, Agamidae)

Abstract Fan-Throated Lizards (Sitana; Agamidae) are a widespread yet little-studied genus of lizards found in dry habitats throughout South Asia. Male lizards in this genus bear a fan-like structure under their throats that is displayed by rapid extension and retraction during the breeding season, particularly during courtship and male–male interactions. Throat-fans vary dramatically in both size and coloration across the genus, ranging from small and white to large and blue, black, and orange. In this paper, I investigate variation in throat-fan morphology and display behavior in eight populations of Fan-Throated Lizards. Displays of these lizards included partial and complete throat-fan extensions, changes in body position, rapid head-turning behavior, and occasional bipedality. Part of the variation in display behavior across these lizards was associated with throat-fan elaboration, and increased throat-fan size and coloration were associated with male-biased sexual size dimorphism but not with change...

Modified ion-Weibel instability as a possible source of wave activity at Comet 67P/Churyumov-Gerasimenko

Abstract. We analytically discuss wave excitation in a homogeneous three component plasma consisting of solar wind protons, electrons and a beam of cometary water ions applied to the plasma environment of comet 67P/Churyumov-Gerasimenko. The resulting dispersion relations are studied in a solar wind rest frame, where a cometary current is solely generated by the water ion beam, and a cometary rest frame representing the rest frame of the Rosetta spacecraft. A modified ion-Weibel instability is excited by the cometary current and predominantly grows perpendicular to this current. The corresponding water ion mode is connected to a frequency of about 40 mHz in agreement with wave measurements of Rosetta's magnetometer in the cometary rest frame. Furthermore, the superposition of the strongest growing waves result in a fan-like phase structure close to the comet.

Theoretical investigation of NpC, NpC2 and NpC4 molecules

The electronic structure and geometrical parameters of ground and low-lying excited states of neptunium mono-, di- and tetracarbides were investigated by relativistic CASSCF/CASPT2 multireference calculations with an all-electron basis set as well as with density functional theory (B3LYP) in conjunction with relativistic pseudopotentials. The CASPT2 calculations were extended with complete active space state interaction calculations in order to include spin–orbit coupling and calculate the absorption electronic spectra. In case of the actinide monocarbides, vibrational frequencies were calculated both for the lowest-energy spin-free and spin–orbit states. For the di- and tetracarbides infrared and Raman spectral characteristics were obtained using DFT calculations. For NpC2, two structures were investigated: the symmetric triangular (Np-C2) structure including an acetylide moiety which was found to be the ground state and the symmetric linear (CNpC) structure. In case of NpC4, fourteen different structures were investigated. The ground state was found to be a planar fan-like structure where neptunium is connected to a bent C 4 moiety. The found structures agree well with the previous results on other actinide carbides (Th, U, Pu, Am). The bonding characteristics of the low-energy structures were analysed on the basis of valence molecular orbitals.

Study of some comets through imaging polarimetry

Comets C/2007 N3 (Lulin), C/2011 L4 (PANSTARRS) and 290P/Jager were observed at phase angles <40○; between 2009 and 2014; with the 0.8m Telescope at Haute-Provence Observatory (OHP) in France. The observations were polarimetric and mainly carried out in the red and near infra-red wavelength domains to reduce gaseous contaminations. The overall shape of the coma of comet Lulin is about circular without evident jet structure. The coma of comet C/2011 L4 is enlarged in the antisolar direction. Jets in a fan-like structure have been noticed between position angles 135°–245° in the treated intensity images. A correlated higher polarization region is noted on the corresponding polarization map. The shape of the coma of 290P/Jager is slightly elongated in the antisolar direction. Deeper negative polarization is found in the inner coma. The whole coma polarization values of these three comets correspond to the synthetic phase curve for comets at similar phase angles and wavelength.

Variations of electroanatomic substrates and markers of successful ablation in idiopathic left ventricular tachycardia: role of electroanatomic substrates and potential mechanism of tachycardia.

The variation of the substrates of verapamil-sensitive idiopathic left ventricular tachycardia (ILVT) was not understood. The purpose of this study was to investigate the variation of electroanatomic substrate [slow conduction zone (SCZ) and left ventricular conduction system (LVCS)] in ILVT and control individuals and markers of successful ablation. Electroanatomical mapping was performed during sinus rhythm in 20 ILVT patients and 26 control individuals with paroxysmal supraventricular tachycardia. LVCS and SCZ were tagged in geometry and the anatomic aspects were investigated. According to the distribution of Purkinje potential, LVCS was distinguished into three types: left bundle branch (LBB) was divided into two discrete fascicles without interconnections; divided into three separate fascicles; and fanlike structure distribution over septum broadly. The length of LBB and its fascicles in patients with ILVT were slightly longer than those of controls (P > 0.05). In the ILVT group, the SCZ was located at the inferoposterior septum in 17, inferior apical septum in one and two SCZs were located at the posterior and mid-septal in the other two patients, which were greater in size and longer in length than those of six controls (P < 0.05). At the crossover junction area with diastolic potential and Purkinje potential, with the size of 1.5 ± 0.4 cm(2), concealed entertainment and ablation were obtained successfully in all patients with ILVT. The anatomy of the LVCS and SCZ is highly variable in patients with ILVT, and the crossover junction area with diastolic potential and Purkinje potential might be a marker of ablation.

Structures and properties of the potassium-doped carbon clusters KCn/KCn +/KCn −(n = 1−10)

A systematic density functional theory study of the potassium-doped small carbon clusters KC n /KC + /KC − (n = 1−10) has been carried out using B3LYP method with 6–311+G* basis set. Several properties including equilibrium geometries, electronic states, relative energies, ionization potentials and electron affinities have been investigated for linear and cyclic isomers. The stability of different structures and states has been discussed according to the relative energy for the same size, and the incremental binding energy for different size. For neutral KC n and cationic KC + clusters, their lowest-lying states mainly have linear structure, while for anionic KC − , they all have fan-like lowest-energy structure, except KC−, KC 3 − , and KC 10 − . The KC n /KC + /KC − clusters have been compared with iso-valent systems LiC n /LiC + /LiC − , NaC n /NaC + /NaC − , and CsC − , and the differences are discussed.

UV spectra of iron-doped carbon clusters FeCnn = 3–6

Electronic transitions of jet-cooled FeCn clusters (n= 3–6) were measured between 230 and 300nm by a mass-resolved 1 +1 resonant two-photon ionization technique. Rotational profiles were simulated based on previous calculations of ground state geometries and compared to experimental observations. Reasonable agreement is found for the planar fan-like structure of FeC3. The FeC4 data indicate a shorter distance between the Fe atom and the bent C4 unit of the fan. The transitions are suggested to be A32⟵B31 for FeC3 and A51⟵A51 for FeC4. In contrast to the predicted C∞v geometry, non-linear FeC5 is apparently observed. Line width broadening prevents analysis of the FeC6 spectrum.

Triangular Antiferromagnet with Nonmagnetic Impurities

The effect of nonmagnetic impurities on the phase diagram of the classical Heisenberg antiferromagnet on a triangular lattice is investigated. We present analytical arguments confirmed by numerical calculations that at zero temperature vacancies stabilize a conical state providing an example of "order by quenched disorder" effect. Competition between thermal fluctuations and the site disorder leads to a complicated H-T phase diagram, which is deduced from the classical MonteCarlo simulations for a representative vacancy concentration. For the XY triangular-lattice antiferromagnet with an in-plane external field, nonmagnetic impurities stabilize the fanlike spin structure. We also briefly discuss the effect of quantum fluctuations.