On the h-triangles of sequentially (S r ) simplicial complexes via algebraic shifting

Recently, Haghighi, Terai, Yassemi, and Zaare-Nahandi introduced the notion of a sequentially (S _r ) simplicial complex. This notion gives a generalization of two properties for simplicial complexes: being sequentially Cohen–Macaulay and satisfying Serre’s condition (S _r ). Let Δ be a (d?1)-dimensional simplicial complex with Γ(Δ) as its algebraic shifting. Also let (h _i,j (Δ))_{0≤j≤i≤d} be the h-triangle of Δ and (h _i,j (Γ(Δ)))_{0≤j≤i≤d} be the h-triangle of Γ(Δ). In this paper, it is shown that for a Δ being sequentially (S _r ) and for every i and j with 0≤j≤i≤r?1, the equality h _i,j (Δ)=h _i,j (Γ(Δ)) holds true.     

Attached primes of the top local cohomology modules with respect to an ideal

Let be a Noetherian local ring and let be an ideal of R. Let M be an R-module of dimension n. In this paper we study the attached primes of the top local cohomology module Received: 12 May 2004     

Theoretical study on thermal behavior of passively Q-switched microchip Nd:YAG laser

This study deals with the thermal characterization of a continuous wave (CW-) and end-pumped passively Q-switched microchip Nd:YAG laser crystal by solving the rate and heat transfer equations in the laser cavity. In this approach, a parametric study has been performed to investigate the influence of the pumping parameters, cooling metal dimension and also the crystal dimension and doping concentration on the thermal behavior of the laser crystal. Obtained results reveal a closed correlation between the mentioned parameters and the thermal behavior of the crystal indicating that a proper selection of the laser parameters is essential to control the crystal's temperature and improve the performance of the laser accordingly.     

Investigation of Sustained BMP Delivery in the Prevention of Medication‐Related Osteonecrosis of the Jaw (MRONJ) in a Rat Model

Medication‐related osteonecrosis of the jaw (MRONJ) poses an ongoing challenge for clinicians and researchers. Currently, there is a lack of preventative measures available for at‐risk patients undergoing tooth extractions, especially those with prior bisphosphonate treatment due to osteoporosis or bone metastasis diagnoses. Here, these issues are addressed using a preventative tissue engineering strategy against MRONJ development. This study evaluates the efficacy of a poly(ethylene glycol)‐heparin hydrogel as a tool for the delivery of arginylglycylaspartic acid (RGD) and recombinant human bone morphogenic protein‐2 (rhBMP‐2). Three groups of skeletally mature rats each receive two doses of intravenous zoledronic acid prior to surgery and undergo extraction of the right first mandibular molar with gingival closure. Experimental groups either have the sockets left empty, filled with hydrogel minus rhBMP‐2, or filled with hydrogel plus rhBMP‐2. Eight weeks postoperatively specimens are analyzed using radiological, histological, and scanning electron microscopy (SEM) techniques. µCT analysis shows increased bone formation with hydrogel/rhBMP‐2 delivery compared to the empty socket. Hydrogel‐treated groups display increased presence of osteocytes and increased osteoclastic action compared to the empty sockets. These results represent the first step toward improved delivery of rhBMP‐2 and a potential MRONJ preventative for patients undergoing bisphosphonate treatment.     

Chemical vapor deposition synthesis of tunable unsubstituted polythiophene

Despite having exceptional electroactive properties, applications of unsubstituted polythiophene (PTh) have been limited due to its insolubility. To overcome this challenge, we have employed oxidative chemical vapor deposition (oCVD) as a unique liquid-free technique to enable the oxidative polymerization of PTh using thiophene as the starting monomer and vanadium oxytrichloride as an effective vaporizable oxidant initiator. Vibrational and phototelectron spectroscopy indicated the formation of unsubstituted polythiophene. Cyclic voltammetry revealed its electrochromic behavior in solution. Significantly, polymer conjugation length and electrical conductivity can be tuned by controlling oCVD process variables. Polymerization is found to be adsorption-limited, so by providing sufficient monomer and limiting the amount of initiator at the growth surface, PTh is believed to be formed through α-α thiophene linkages.     

Establishing an Iranian medical laboratory standard based on ISO 15189

To strengthen clinical laboratories’ capabilities, the Reference Health Laboratory (RHL) of the Ministry of Health decided to compile a national professional laboratory standard to be followed by all medical laboratories in the country. Providing a national laboratory standard, as approved criteria for competency assessment, is also essential for establishment of a national accreditation system for medical laboratories. ISO 15189 addresses different processes and activities in a medical laboratory, but considering the local situation and limitations in the country it was not feasible to implement all the requirements of ISO 15189 at once in laboratories in different sectors and in different provinces of the country. For this reason, the RHL decided to define and publish the national standard, as minimum quality requirements that could be mandatory for all clinical laboratories throughout the country. After conducting a countrywide situation analysis, a national standard was composed by RHL expert committees and officially announced in September 2007. The main reference of this standard was ISO 15189:2007, although some important technical details were added to it from other credible references, such as WHO documents and CLSI guidelines. In this study, the Iranian national standard is compared to ISO 15189:2007 in terms of format and content in order to show how an international standard was localized for compiling a national standard.     

Rational design of biomimetic molecularly imprinted materials: theoretical and computational strategies for guiding nanoscale structured polymer development

In principle, molecularly imprinted polymer science and technology provides a means for ready access to nano-structured polymeric materials of predetermined selectivity. The versatility of the technique has brought it to the attention of many working with the development of nanomaterials with biological or biomimetic properties for use as therapeutics or in medical devices. Nonetheless, the further evolution of the field necessitates the development of robust predictive tools capable of handling the complexity of molecular imprinting systems. The rapid growth in computer power and software over the past decade has opened new possibilities for simulating aspects of the complex molecular imprinting process. We present here a survey of the current status of the use of in silico-based approaches to aspects of molecular imprinting. Finally, we highlight areas where ongoing and future efforts should yield information critical to our understanding of the underlying mechanisms sufficient to permit the rational design of molecularly imprinted polymers.     

Closed-form dynamics of a hexarot parallel manipulator by means of the principle of virtual work

In this research, a systematic approach to solving the inverse dynamics of hexarot manipulators is addressed using the methodology of virtual work. For the first time, a closed form of the mathematical formulation of the standard dynamic model is presented for this class of mechanisms. An efficient algorithm for solving this closed-form dynamic model of the mechanism is developed and it is used to simulate the dynamics of the system for different trajectories. Validation of the proposed model is performed using SimMechanics and it is shown that the results of the proposed mathematical model match with the results obtained by the SimMechanics model.     

Stability analysis of a nonlinear rotating asymmetrical shaft near the resonances

An asymmetrical rotating shaft with unequal mass moments of inertia and flexural rigidities in the direction of principal axes is considered. In this system, there are two excitation sources, including a harmonic excitation due to the dynamic imbalances and a parametric excitation due to shaft asymmetry. Nonlinearities are due to the in-extensionality of the shaft and large amplitude. In this study, harmonic and parametric resonances due to the mentioned effects are considered. The influences of inequality of mass moments of inertia and flexural rigidities in the direction of principal axes, inequality between two eccentricities corresponding to the principal axes and external damping on the stability and bifurcation of steady state response of the rotating asymmetrical shaft are investigated. In addition, the characteristic of stable stationary points and loci of bifurcation points as function of damping coefficient are determined. In order to analyze the resonances of the system the multiple scales method is applied to the complex form of partial differential equations of motion. The achieved results show a good agreement with those of numerical computation.