Spatially resolved ultrasonic attenuation in resistance spot welds: implications for nondestructive testing

Spatial variation of ultrasonic attenuation and velocity has been measured in plane parallel specimens extracted from resistance spot welds. In a strong weld, attenuation is larger in the nugget than in the parent material, and the region of increased attenuation is surrounded by a ring of decreased attenuation. In the center of a stick weld, attenuation is even larger than in a strong weld, and the low-attenuation ring is absent. These spatial variations are interpreted in terms of differences in grain size and martensite formation. Measured frequency dependences indicate the presence of an additional attenuation mechanism besides grain scattering. The observed attenuations do not vary as commonly presumed with weld quality, suggesting that the common practice of using ultrasonic attenuation to indicate weld quality is not a reliable methodology.     

Heterostructure wavelength division demultiplexers using photonic crystal ring resonators

In this paper, we demonstrate a new type of two-dimensional photonic crystal wavelength division demultiplexers based on ring resonators that can be applicable to photonic integrated circuits. The proposed structure mechanism is performed based on coupling between a waveguide and a ring resonator. Based on the calculated position, this structure is designed and verified by finite-difference time-domain computation; our simulation by using this method results over 82% output efficiency. We use a heterostructure which is constructed of three different values of dielectric constant to obtain our wavelength division demultiplexer.     

Targeted Therapy of B7 Family Checkpoints as an Innovative Approach to Overcome Cancer Therapy Resistance: A Review from Chemotherapy to Immunotherapy

It is estimated that there were 18.1 million cancer cases worldwide in 2018, with about 9 million deaths. Proper diagnosis of cancer is essential for its effective treatment because each type of cancer requires a specific treatment procedure. Cancer therapy includes one or more approaches such as surgery, radiotherapy, chemotherapy, and immunotherapy. In recent years, immunotherapy has received much attention and immune checkpoint molecules have been used to treat several cancers. These molecules are involved in regulating the activity of T lymphocytes. Accumulated evidence shows that targeting immune checkpoint regulators like PD-1/PD-L1 and CTLA-4 are significantly useful in treating cancers. According to studies, these molecules also have pivotal roles in the chemoresistance of cancer cells. Considering these findings, the combination of immunotherapy and chemotherapy can help to treat cancer with a more efficient approach. Among immune checkpoint molecules, the B7 family checkpoints have been studied in various cancer types such as breast cancer, myeloma, and lymphoma. In these cancers, they cause the cells to become resistant to the chemotherapeutic agents. Discovering the exact signaling pathways and selective targeting of these checkpoint molecules may provide a promising avenue to overcome cancer development and therapy resistance. Highlights: (1) The development of resistance to cancer chemotherapy or immunotherapy is the main obstacle to improving the outcome of these anti-cancer therapies. (2) Recent investigations have described the involvement of immune checkpoint molecules in the development of cancer therapy resistance. (3) In the present study, the molecular participation of the B7 immune checkpoint family in anticancer therapies has been highlighted. (4) Targeting these immune checkpoint molecules may be considered an efficient approach to overcoming this obstacle.     

Effect of biopolymer blends on physical and Acoustical properties of biocomposite foams

Bio‐based foams are the solution to environmental concerns raised by petrochemical‐based open cell foams used in various industries for sound absorption. While conventional petrochemical‐based polymers take centuries to degrade or may not degrade at all, bio‐based polymers decompose to biomass, water, and carbon dioxide in a matter of months when exposed to proper environment. To increase the potential of replacing current petrochemical foams, mechanical as well as acoustic characteristics of bio‐based foams need to be improved. This article studies the effect of blending two bio‐based polymers and physics of the blends on acoustic and mechanical properties of resulting polymer composite foams. Different blends of polylactide with three grades of polyhydroxyalkanoates were foamed and characterized based on acoustic and mechanical performance. Rheological properties of pure polymers as well as their blends were studied and effect of polymer blends on acoustic absorption of the resulting foams was investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1002–1013     

Investigation of antioxidant and electron beam radiation effects on the thermal oxidation stability of low-density polyethylene

Effect of various antioxidants on the thermal oxidation stability of LDPE and X-LDPE has been investigated. To achieve this purpose, miscellaneous commercial grade antioxidants such as Irganox 1010, Irganox1076, Irgafos168, Irganox B225, and Chimassorb 944 were selected. Then, formulations based on different content of antioxidant were prepared. The samples were crosslinked by exposure to electron beam irradiation. To assess the thermal oxidation stability of samples, oxidation induction time (OIT) test was accomplished on both the irradiated and unirradiated specimens. Ageing tests were carried out in order to evaluate the thermal oxidation stability of irradiated X-LDPE. The results indicate that Irganox 1010 is the most effective antioxidant amongst the selected ones, concerning thermal oxidation stability of LDPE, before and after aging test.     

A mixed radiotherapy and chemotherapy model for treatment of cancer with metastasis

In this paper, a mathematical model of cancer treatment, in the form of a system of ordinary differential equations, by chemotherapy and radiotherapy where there is metastasis from a primary to a secondary site has been proposed and analyzed. The interaction between immune cells and cancer cells has been examined, and the chemotherapy agent has been considered as a predator on both normal and cancer cells. The metastasis may be time delayed. For better investigation of the treatment process and based on physical investigation, the immanent effects of inputs on cancer dynamic have been investigated. It is supposed that the interaction between NK cells and tumor cells changes during the chemotherapy. This novel approach is useful not only to gain a broad understanding of the specific system dynamics but also to guide the development of combination therapies. The analysis is carried out both analytically (where possible) and numerically. By considering such immanent effects, the tumor‐free equilibrium point will be stable at the end of treatment, and the tumor can not recur again, and the patient will totally recover. So, the present analysis suggests that a proper treatment method should change the dynamics of the cancer instead of only reducing the population of cancer cells. Copyright © 2016 John Wiley & Sons, Ltd.     

Optimal economic load dispatch based on wind energy and risk constrains through an intelligent algorithm

This article focus on optimal economic load dispatch based on an intelligent method of shark smell optimization (SSO). In this problem, the risk constrains has been considered which has root in uncertainity and unpredictable behavior of wind power. Regarding to increasing of this clean energy in power systems and un‐dispatchable behavior of wind power, its conditional value at risk index considered in this article which consists of loss from load and "spilling" wind energy connected with unpredictable imbalances among generation and load. This problem has been considered as an optimization problem based on SSO that evaluate the balance between cost and risk. This algorithm is based on distinct shark smell abilities for localizing the prey. In sharks' movement, the concentration of the odor is an important factor to guide the shark to the prey. In other words, the shark moves in the way with higher odor concentration. This characteristic is used in the proposed SSO algorithm to find the solution of an optimization problem. Effectiveness of the proposed method has been applied over 30‐bus power system in comparison with other techniques. © 2016 Wiley Periodicals, Inc. Complexity 21: 494–506, 2016     

Mesoporous Molecular Sieve MCM‐41 as a Novel and Efficient Catalyst to Synthesis of 2‐Substituted Benzimidazoles

o‐Phenylenediamine derivatives readily react with benzoyl chloride derivatives in the presence of MCM‐41 as catalyst to yield 2‐substituted benzimidazoles in very good yields.     

Projections onto invariant subspaces of some banach algebras

In this paper, among other things, the author studies the weak^＊-closed left translation invariant complemented subspace of semigroup algebras and group algebras. Also, the author studies the relationships between projections and amenability.     

Complex aperture networks

A complex network approach is proposed for studying the shear behavior of a rough rock joint. Similarities between aperture profiles are established, and a functional complex network—in each shear displacement—is constructed in two directions: parallel and perpendicular to the shear direction. We find that the growth of the clustering coefficient and that of the number of edges are approximately scaled with the development of shear strength and hydraulic conductivity, which could possibly be utilized to estimate and formulate a friction law and the evolution of shear distribution over asperities. Moreover, the frictional interface is mapped in the global–local parameter space of the corresponding functional friction network, showing the evolution path and, eventually, the residual stage. Furthermore, we show that with respect to shear direction, parallel aperture patches are more adaptable to environmental stimuli than perpendicular profiles. We characterize the pure-contact profiles using the same approach. Unlike the first case, the later networks show a growing trend while in the residual stage; a saturation of links is encoded in contact networks.