Exponential and power-law renormalization in phonon-assisted tunneling

We investigate the spinless Anderson-Holstein model routinely employed to describe the basic physics of phonon-assisted tunneling in molecular devices. Our focus is on small to intermediate electron-phonon coupling; we complement a recent strong coupling study [Phys.~Rev.~B {87}, 075319 (2013)]. The entire crossover from the antiadiabatic regime to the adiabatic one is considered. Our analysis using the essentially analytical functional renormalization group approach backed-up by numerical renormalization group calculations goes beyond lowest order perturbation theory in the electron-phonon coupling. In particular, we provide an analytic expression for the effective tunneling coupling at particle-hole symmetry valid for all ratios of the bare tunnel coupling and the phonon frequency. It contains the exponential polaronic as well as the power-law renormalization; the latter can be traced back to x-ray edge-like physics. In the antiadiabatic and the adiabatic limit this expression agrees with the known ones obtained by mapping to an effective interacting resonant level model and lowest order perturbation theory, respectively. Away from particle-hole symmetry, we discuss and compare results from several approaches for the zero temperature electrical conductance of the model.Comment: 11 pages, 6 figures, Published versio

Influence of phonon-assisted tunneling on the linear thermoelectric transport through molecular quantum dots

We investigate the effect of vibrational degrees of freedom on the linear thermoelectric transport through a single-level quantum dot described by the spinless Anderson-Holstein impurity model. To study the effects of strong electron-phonon coupling, we use the nonperturbative numerical renormalization group approach. We also compare our results, at weak to intermediate coupling, with those obtained by employing the functional renormalization group method, finding good agreement in this parameter regime. When applying a gate voltage at finite temperatures, the inelastic scattering processes, induced by phonon-assisted tunneling, result in an interesting interplay between electrical and thermal transport. We explore different parameter regimes and identify situations for which the thermoelectric power as well as the dimensionless figure of merit are significantly enhanced via a Mahan-Sofo type of mechanism. We show, in particular, that this occurs at strong electron-phonon coupling and in the antiadiabatic regime.Comment: 14 pages, 8 figures, Published versio

Nonequilibrium thermoelectric transport through vibrating molecular quantum dots

We employ the functional renormalization group to study the effects of phonon-assisted tunneling on the nonequilibrium steady-state transport through a single level molecular quantum dot coupled to electronic leads. Within the framework of the spinless Anderson-Holstein model, we focus on small to intermediate electron-phonon couplings, and we explore the evolution from the adiabatic to the antiadiabatic limit and also from the low-temperature non-perturbative regime to the high temperature perturbative one. We identify the phononic signatures in the bias-voltage dependence of the electrical current and the differential conductance. Considering a temperature gradient between the electronic leads, we further investigate the interplay between the transport of charge and heat. Within the linear response regime, we compare the temperature dependence of various thermoelectric coefficients to our earlier results obtained within the numerical renormalization group [Phys.~Rev.~B {\bf 96}, 195156 (2017)]. Beyond the linear response regime, in the context of thermoelectric generators, we discuss the influence of molecular vibrations on the output power and the efficiency. We find that the molecular energy dissipation, which is inevitable in the presence of phonons, is significantly suppressed in the antiadiabatic limit resulting in the enhancement of the thermoelectric efficiency.Comment: 11 pages, 7 figures, Published versio

The immunopathobiology of T cells in stress condition: a review

Several factors impact the immune responses such as the chemical nature of antigens, the physiologic and metabolic condition of the responsive cells, the site of antigen recognition, and neuroendocrine and pharmacological received agents. Incompatibility of host immune responses to the entrapped antigens leads to an immune pathological manner instead of an immune protection which results in the disharmony of the immune effective factors. Besides the fact that stress is one of the most common effective factors in human life, it also contributed to the protection, suppression, and pathology of the immune system. In this review article, the direct and indirect effects of the stress on the function of T cells and the contributed mechanism of action will be discussed. © 2020, Cell Stress Society International

Ectoparasites of hedgehogs: From flea mite phoresy to their role as vectors of pathogens

Hedgehogs are synanthropic mammals, reservoirs of several vector-borne pathogens and hosts of ectoparasites. Arthropod-borne pathogens (i.e., Rickettsia spp., Borrelia spp., and Anaplasmataceae) were molecularly investigated in ectoparasites collected on hedgehogs (n = 213) from Iran (161 Hemiechinus auritus, 5 Erinaceus concolor) and Italy (47 Erinaceus europaeus). In Iran, most animals examined (n = 153; 92.2%) were infested by ticks (Rhipicephalus turanicus, Hyalomma dromedarii), and 7 (4.2%) by fleas (Archeopsylla erinacei, Ctenocephalides felis). Of the hedgehogs infested by arthropods in Italy (i.e., 44.7%), 18 (38.3%) were infested by fleas (Ar. erinacei), 7 (14.9%) by ticks (Haemaphysalis erinacei, Rh. turanicus, Rhipicephalus sanguineus sensu lato), and 6 (12.8%) by mites (Caparinia tripilis, Acarus nidicolous, Ornithonyssus spp.). Phoretic behavior of C. tripilis on Ar. erinacei was detected in two flea specimens from Italy. At the molecular analysis Rickettsia spp. was detected in 93.3% of the fleas of Italy. In Iran, Rickettsia spp. was detected in 8.0% out of 212 Rh. turanicus ticks, and in 85.7% of the Ar. erinacei fleas examined. The 16S rRNA gene for Ehrlichia/Anaplasma spp. was amplified in 4.2% of the 212 Rh. turanicus ticks. All sequences of Rickettsia spp. from fleas presented 100% nucleotide identity with Rickettsia asembonensis, whereas Rickettsia spp. from Rh. turanicus presented 99.84%–100% nucleotide identity with Rickettsia slovaca, except for one sequence, identical to Rickettsia massiliae. The sequences of the 16S rRNA gene revealed 99.57%–100% nucleotide identity with Anaplasma spp., except for one, identical to Ehrlichia spp. A new phoretic association between C. tripilis mites and Ar. erinacei fleas has been herein reported, which could be an important route for the spreading of this mite through hedgehog populations. Additionally, spotted fever group rickettsiae were herein detected in ticks and fleas, and Anaplasma/Ehrlichia spp. in ticks, suggesting that hedgehogs play a role as reservoirs for these vector-borne pathogens

Engineering of 2D nanomaterials to trap and kill SARS-CoV-2 : a new insight from multi-microsecond atomistic simulations

In late 2019, coronavirus disease 2019 (COVID-19) was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Spike protein is one of the surface proteins of SARS-CoV-2 that is essential for its infectious function. Therefore, it received lots of attention for the preparation of antiviral drugs, vaccines, and diagnostic tools. In the current study, we use computational methods of chemistry and biology to study the interaction between spike protein and its receptor in the body, angiotensin-I-converting enzyme-2 (ACE2). Additionally, the possible interaction of two-dimensional (2D) nanomaterials, including graphene, bismuthene, phosphorene, p-doped graphene, and functionalized p-doped graphene, with spike protein is investigated. The functionalized p-doped graphene nanomaterials were found to interfere with spike protein better than the other tested nanomaterials. In addition, the interaction of the proposed nanomaterials with the main protease (M-pro) of SARS-CoV-2 was studied. Functionalized p-doped graphene nanomaterials showed more capacity to prevent the activity of M-pro. These 2D nanomaterials efficiently reduce the transmissibility and infectivity of SARS-CoV-2 by both the deformation of the spike protein and inhibiting the M-pro. The results suggest the potential use of 2D nanomaterials in a variety of prophylactic approaches, such as masks or surface coatings, and would deserve further studies in the coming years.Peer reviewe

Molecular scale study on the interactions of biocompatible nanoparticles with macrophage membrane and blood proteins

Macrophage targeting and researches centered on immunological responses have received interest thanks to studies unveiling the significant role of macrophages in inflammatory diseases and cancer. In this regard, we have selected four types of nanoparticles (NPs), including acetalated dextran-based nano-carrier functionalized with atrial natriuretic peptide and linTT1(AcDEX-PEG-TT1-ANP), PEGylated acetalated dextran (AcDEX-PEG), acetalated dextran (AcDEX), and hyaluronic acid (HA) to investigate their interactions with macrophage membrane. Using microsecond coarse-grained molecular dynamics (MD) simulations, we studied the interactions between the NPs and the macrophage membrane and subsequent immunological reactions that occur after the penetration of the NPs within the macrophage cell. Different parameters that determine the strength and amount of macrophage membrane interaction were measured and compared for all four types of NPs. The results showed that AcDEX-PEG-TT1-ANP has the most favorable interaction with the macrophage membrane while HA has the least favorable results by comparison. Moreover, drug encapsulation and release in different pH conditions showed the pH-responsivity of the considered NPs for drug delivery in acidic environments. On the other hand, evaluations with human serum albumin (HSA), fibrinogen (Fib), and transferrin (Tf) declared that peptide modified AcDEX polymers are the most probable NPs to absorb a layer of the protein corona

Determination and Diversity of Bovine Coccidia in Zabol, East of Iran

The present study was designed to investigate the prevalence of Eimeria spp. in Zabol, east of Iran. The samples were examined microscopically for the presence of oocysts from February 2015 to December 2016. Out of 196 cattle, 124 (63.26%) were identified to be positive for Eimeria species. Eight species of Eimeria were found as follows: E. bovis (42.54%), E. zuernii (38.67%), E. subspherica (5.52%), E. brasiliensis (4.97%), E. ellipsoidalis (4.41%), E. cylindrical (1.65%), E. pellita (1.65%), and E. wyomingensis (0.55%). Multiple infections with two or three species were identified in 56 (45.16%) and 2 (1.61%) cases, respectively. The infection rate was observed to be higher in calves (75%) as compared to adult cattle (59.02%). The prevalence of Eimeria was greater in female cattle (67.94%). The highest prevalence and mean number of oocysts were observed in winter (69%) and autumn (209.09), respectively. All the faecal samples had an oocysts per gram of feces (OPG) less than 1000. The prevalence of infection and mean OPG were directly correlated with rainfall and relative humidity and inversely correlated with temperature. Considering the high prevalence of bovine coccidiosis in Zabol, increasing awareness of farmers and veterinarians regarding the economic importance of bovine coccidiosis should be regarded as an important factor in preventing and controlling the infection. Keywords: Prevalence, Cattle, Eimeria spp., Risk factors, Ira

Spectrum of mutations of thalassemia among couples from izeh city, khuzestan province, iran

Hemoglobinopathies are inherited blood disorders with an autosomal recessive pattern. We aimed to evaluate the frequency of mutations of thalassemia and hemoglobinopathies among couples referred to health centers of Izeh in Khuzestan Province, Iran. Methods: This cross-sectional study was performed on 150 couples referred to Izeh Health Centers in 2015-2018. DNA was isolated from peripheral venous blood samples and then the HBB gene was analyzed by using Sanger sequencing. For molecular analysis of α-globin gene, multiplex Gap-PCR and ARMS-PCR was performed to identify mutations of α-thalassemia. Results: DNA analysis revealed 13 different mutations for beta thalassemia in studied couples. Three mutations including 36/37 (-T), IVS-II-1 (G>A) and IVS-I-110 (G>A) accounted for 20.7, 19.3 and 13.3% of beta thalassemia mutations, respectively. For alpha thalassemia; α3.7 (49.5%),--MED (19.1 %) and-α4.2 (3.1%) were identified as the most common mutations. Conclusion: Considering common alpha and beta mutations of this geographic area of Iran could be useful concerning genetic counselling in of the population where the rate of consanguineous marriage is high