Abstract
The quest for lowering energy consumption during thin film growth, as by magnetron sputtering, becomes of particular importance in view of sustainable development goals. A recently proposed ...solution combining high power impulse and direct current magnetron sputtering (HiPIMS/DCMS) relies on the use of heavy metal-ion irradiation, instead of conventionally employed resistive heating, to provide sufficient adatom mobility, in order to obtain high-quality dense films. The major fraction of process energy is used at the sputtering sources rather than for heating the entire vacuum vessel. The present study aims to investigate the W
+
densification effects as a function of increasing Al content in (Ti
1-
y
Al
y
)
1-
x
W
x
N films covering the entire range up to the practical solubility limits (
y
~ 0.67). Layers with high Al content are attractive to industrial applications as the high temperature oxidation resistance increases with increasing Al concentration. The challenge is, however, to avoid precipitation of the hexagonal wurtzite AlN phase, which is softer. We report here that (Ti
1-
y
Al
y
)
1-
x
W
x
N layers with
y
= 0.66 and
x
= 0.05 grown by a combination of W-HiPIMS and TiAl-DCMS with the substrate bias
V
s
synchronized to the W
+
-rich fluxes (to provide mobility in the absence of substrate heating) possess single-phase NaCl-structure, as confirmed by XRD and SAED patterns. The evidence provided by XTEM images and the residual oxygen content obtained from ERDA analyses reveals that the alloy films are dense without discernable porosity. The nanoindentation hardness is comparable to that of TiAlN films grown at 400–500 °C, while the residual stresses are very low. We established that the adatom mobility due to the heavy ion W
+
irradiation (in place of resistive heating) enables the growth of high-quality coatings at substrate temperatures not exceeding 130 °C provided that the W
+
momentum transfer per deposited metal atom is sufficiently high. The benefit of this novel film growth approach is not only the reduction of the process energy consumption by 83%, but also the possibility to coat temperature-sensitive substrates.
Hydrogen-based compounds under ultrahigh pressure, such as the polyhydrides H3S and LaH10, superconduct through the conventional electron-phonon coupling mechanism to attain the record critical ...temperatures known to date. Here we exploit the intrinsic advantages of hydrogen to strongly enhance phonon-mediated superconductivity in a completely different system, namely, a two-dimensional material with hydrogen adatoms. We find that van Hove singularities in the electronic structure, originating from atomiclike hydrogen states, lead to a strong increase of the electronic density of states at the Fermi level, and thus of the electron-phonon coupling. Additionally, the emergence of high-frequency hydrogen-related phonon modes in this system boosts the electron-phonon coupling further. As a concrete example, we demonstrate the effect of hydrogen adatoms on the superconducting properties of monolayer MgB2 , by solving the fully anisotropic Eliashberg equations, in conjunction with a first-principles description of the electronic and vibrational states, and their coupling. We show that hydrogenation leads to a high critical temperature of 67 K, which can be boosted to over 100 K by biaxial tensile strain.
Hybrid high power impulse/direct current magnetron sputtering (HiPIMS/DCMS) film growth technique with metal-ion-synchronized substrate bias allows for significant energy savings as compared to ...conventional PVD methods. For carefully selected type of metal ion irradiation, taking into account ion mass, ionization potential, and reactivity towards working gas, fully dense and hard films can be obtained with no intentional substrate heating. The thermally-driven adatom mobility, which is an essential densification mechanism in conventional film growth that takes place at elevated temperatures, is replaced with that supplied by effective low-energy recoil creation. In this contribution we explore effects of the high-mass W+ irradiation, which has proven to be the most efficient in densifying Ti0.50Al0.50N layers, serving here as a model system, grown with no substrate heating. We study the effects of two essential parameters: W+ energy EW+ and W concentration x, on film porosity, phase content, nanostructure, and mechanical properties. EW+ varies from ~90 to ~630 eV (controlled by substrate bias voltage amplitude Vs) and x from 0.02 to 0.12 (controlled by the HiPIMS pulse length), while the HiPIMS peak target current is kept constant. Results reveal that a strong coupling exists between the W+ incident energy and the minimum W concentration required to grow dense layers.
•The effect of W+ irradiation on densification of TiAlN films is studied.•Films are grown by W-HiPIMS/TiAl-DCMS with W+-synchronized bias.•No external heating is applied and substrate temperature is lower than 130 °C.•The effect of W+ energy EW+ and W concentration x on film properties is studied.•Fully-dense films can be obtained with low EW+ without high residual stress.
In view of the increasing demand for achieving sustainable development, the quest for lowering energy consumption during thin film growth by magnetron sputtering becomes of particular importance. In ...addition, there is a demand for low-temperature growth of dense, hard coatings for protecting temperature-sensitive substrates. Here, we explore a method, in which thermally-driven adatom mobility, necessary to obtain high-quality fully-dense films, is replaced with that supplied by effective low-energy recoil creation resulting from high-mass metal ion irradiation of the growing film surface. This approach allows the growth of dense and hard films with no external heating at substrate temperatures Ts not exceeding 130 °C in a hybrid high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) setup involving a high mass (m > 180 amu) HiPIMS target and metal-ion-synchronized bias pulses. We specifically investigate the effect of the metal ion mass on the extent of densification, phase content, nanostructure, and mechanical properties of metastable cubic Ti0.50Al0.50N based thin films, which present outstanding challenges for phase stability control. Ti0.50Al0.50N based thin films are irradiated by group VIB transition metal (TM) target ions generated by Me-HiPIMS discharge, in which Me = Cr (mCr = 52.0 amu), Mo (mMo = 96.0 amu), and W (mW = 183.8 amu). Three series of (Ti1-yAly)1-xMexN films are grown with x = Me/(Me+Al+Ti) varied intentionally by adjusting the DCMS powers, while y = Al/(Al+Ti) also varies as a result of Me+ ion irradiation. Results reveal a strong dependence of film properties on the mass of the HiPIMS-generated metal ions. All layers deposited with Cr+ irradiation exhibit porous nanostructure, high oxygen content, and poor mechanical properties. In contrast, (Ti1-yAly)1-xWxN films are fully-dense even with the lowest W concentration, x = 0.09, show no evidence of hexagonal AlN precipitation, and exhibit state-of the-art mechanical properties typical of Ti0.50Al0.50N grown at 500 °C. The process energy consumption is lowered by 64% with no negative impact on the coating quality. TRIM simulations provide an insight into the densification mechanisms.
•(Ti1-yAly)1-xMexN (Me = Cr, Mo, W) thin films are grown by Me-HiPIMS/TiAl-DCMS.•The effect of the metal ion mass on the Ti0.50Al0.50N densification is studied.•No external heating is applied during coating and substrate temperature is lower than 130 °C.•Dense films are achieved with W ions resulting in hardness of 32 GPa.•Process energy consumption can be decreased by 64%.
The explosive development of quantum magnonics is associated with the possibility of its use as macroscopic quantum systems. In particular, they can find an application for quantum computing ...processors and other devices. The recently discovered phenomenon of magnon Bose-Einstein condensation and coherent precession of magnetization can be used for these purposes. Our letter describes a method for the optical observation of the coherently precessing magnetization in conditions when the concentration of magnons reaches the value necessary for their quantum condensation. The investigations were conducted in the out-of-plane magnetized yttrium iron garnet films. The required magnon density was achieved by magnetic resonance technique. The magneto-optical imaging method provides such important parameters of the coherent spin dynamics as the amplitude and phase distributed all over the sample. It should become an indispensable read-out tool for the upcoming quantum technologies based on the magnon Bose-Einstein condensation.
The eukaryotic translation initiation factor 4E (eIF4E) is the master regulator of cap-dependent protein synthesis. Overexpression of eIF4E is implicated in diseases such as cancer, where ...dysregulation of oncogenic protein translation is frequently observed. eIF4E has been an attractive target for cancer treatment. Here we report a high-resolution X-ray crystal structure of eIF4E in complex with a novel inhibitor (i4EG-BiP) that targets an internal binding site, in contrast to the previously described inhibitor, 4EGI-1, which binds to the surface. We demonstrate that i4EG-BiP is able to displace the scaffold protein eIF4G and inhibit the proliferation of cancer cells. We provide insights into how i4EG-BiP is able to inhibit cap-dependent translation by increasing the eIF4E-4E-BP1 interaction while diminishing the interaction of eIF4E with eIF4G. Leveraging structural details, we designed proteolysis targeted chimeras (PROTACs) derived from 4EGI-1 and i4EG-BiP and characterized these on biochemical and cellular levels. We were able to design PROTACs capable of binding eIF4E and successfully engaging Cereblon, which targets proteins for proteolysis. However, these initial PROTACs did not successfully stimulate degradation of eIF4E, possibly due to competitive effects from 4E-BP1 binding. Our results highlight challenges of targeted proteasomal degradation of eIF4E that must be addressed by future efforts.
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•Design of an eIF4E inhibitor i4EG-BiP, that binds to an internal site.•High resolution crystal structure of eIF4E bound to the inhibitor i4EG-BiP.•Specific inhibition of cap-dependent translation by i4EG-BiP.•Design cell-permeable eIF4E-targeting PROTACs based on i4EG-BiP and 4EGI-1.•Synthesis and testing of eIF4E PROTACs in biophysical and cellular assays.
Aim
In addition to ischemia there is also anastomotic ends tension proven to be a risk factor for anastomotic leak. HT vascular ligation is accepted as a rule, in attempt to achieve tension-free ...anastomosis. LT is a preferred option, based on the more accurate preservation of proximal intestinal segment microperfusion and lower risk of damage to the hypogastric plexus. The aim of this study is evaluation of comparative indicators in high tie (HT) and low tie (LT) laparoscopic rectal resections.
Methods
A prospective nonrandomized comparative cohort study of patients in our department with cancer of the rectum in clinical stage I–III, operated on in laparoscopic approach over a 6-years period.
Results
For the period 2015–2020, a number of 208 laparoscopic surgeries have been done for rectal cancer. Patients were divided into three groups—group A with HT vascular ligation 116 pts. (69%), group B—53 pts. (25%), underwent low ligation—LT and group C—39pts. (19%) low tie plus lymph node dissection of the apical LN group (LT-appic LND). The distribution was made without randomization, based on the operators’ expertise. Anastomotic leaks were 3.8% in group A, 3.0% in group B and 2.9% in group C (
p
> 0.05) with no significance difference. There is no significant difference in the number of lymph nodes obtained in group A and group B, while in group C the number of the harvested lymph nodes was higher (
p
< 0.05). The indicators for intestinal / defecation dysfunction, as well as for urinary/sexual dysfunction, according to our data, are significantly more favorable in patients with LT, in contrast to the other two groups.
Conclusion
HT vascular ligation attempts to achieve tension-free anastomosis and more harvested lymph nodes. However, LT could be a preferred option, based on the lack of significant evidence for a difference in specific oncological survival and due to more accurate preservation of proximal intestinal segment microperfusion to prevent anastomosis dehiscence, also for its lower risk of damage to the hypogastric plexus. Splenic flexure mobilization provides elongation of the proximal intestinal segment, but has no proven effect on anastomotic leakage incidence. It increases surgical duration and is in fact necessary in up to 30% of the cases. At the present moment there is no precise data whether LT has an advantage in terms of prevention of autonomic nervous and urogenital dysfunction. New prospective randomized and highly probative studies are needed to standardize the procedures in specific clinical situations.
Magnons have demonstrated enormous potential for the next generation of information technology and quantum computing. In particular, the coherent state of magnons resulting from their Bose-Einstein ...condensation (mBEC) is of great interest. Typically, mBEC is formed in the magnon excitation region. Here we demonstrate for the first time by optical methods the permanent existence of mBEC at large distances from the magnon excitation region. The homogeneity of the mBEC phase is also demonstrated. The experiments were carried out on films of yttrium iron garnet magnetized perpendicular to the surface and at room temperature. We use the method described in this article to develop coherent magnonics and quantum logic devices.
Little is known about the mechanisms converting psychosocial stress into cellular dysfunction. Various genes, up-regulated in atherosclerosis but also by psychosocial stress, are controlled by the ...transcription factor nuclear factor κB (NF-κB). Therefore, NF-κB is a good candidate to convert psychosocial stress into cellular activation. Volunteers were subjected to a brief laboratory stress test and NF-κB activity was determined in peripheral blood mononuclear cells (PBMC), as a window into the body and because PBMC play a role in diseases such as atherosclerosis. In 17 of 19 volunteers, NF-κB was rapidly induced during stress exposure, in parallel with elevated levels of catecholamines and cortisol, and returned to basal levels within 60 min. To model this response, mice transgenic for a strictly NF-κB-controlled β-globin transgene were stressed by immobilization. Immobilization resulted in increased β-globin expression, which could be reduced in the presence of the α1-adrenergic inhibitor prazosin. To define the role of adrenergic stimulation in the up-regulation of NF-κB, THP-1 cells were induced with physiological amounts of catecholamines for 10 min. Only noradrenaline resulted in a dose- and time-dependent induction of NF-κB and NF-κB-dependent gene expression, which depended on pertussis-toxin-sensitive G protein-mediated phosphophatidylinositol 3-kinase, Ras/Raf, and mitogen-activated protein kinase activation. Induction was reduced by α1- and β-adrenergic inhibitors. Thus, noradrenaline-dependent adrenergic stimulation results in activation of NF-κB in vitro and in vivo. Activation of NF-κB represents a downstream effector for the neuroendocrine response to stressful psychosocial events and links changes in the activity of the neuroendocrine axis to the cellular response.
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