57Fe nuclear resonance vibrational spectroscopic studies of tetranuclear iron clusters bearing terminal iron(iii)-oxido/hydroxido moieties.

57Fe nuclear resonance vibrational spectroscopy (NRVS) has been applied to study a series of tetranuclear iron ([Fe4]) clusters based on a multidentate ligand platform (L3-) anchored by a 1,3,5-triarylbenzene linker and pyrazolate or (tertbutylamino)pyrazolate ligand (PzNH t Bu-). These clusters bear a terminal Fe(iii)-O/OH moiety at the apical position and three additional iron centers forming the basal positions. The three basal irons are connected with the apical iron center via a µ4-oxido ligand. Detailed vibrational analysis via density functional theory calculations revealed that strong NRVS spectral features below 400 cm-1 can be used as an oxidation state marker for the overall [Fe4] cluster core. The terminal Fe(iii)-O/OH stretching frequencies, which were observed in the range of 500-700 cm-1, can be strongly modulated (energy shifts of 20-40 cm-1 were observed) upon redox events at the three remote basal iron centers of the [Fe4] cluster without the change of the terminal Fe(iii) oxidation state and its coordination environment. Therefore, the current study provides a quantitative vibrational analysis of how the remote iron centers within the same iron cluster exert exquisite control of the chemical reactivities and thermodynamic properties of the specific iron site that is responsible for small molecule activation.

Multicaloric Cryocooling Using Heavy Rare-Earth Free La(Fe,Si)13-Based Compounds.

The transition toward a carbon-neutral society based on renewable energies goes hand in hand with the availability of energy-efficient technologies. Magnetocaloric cooling is a very promising refrigeration technology to fulfill this role regarding cryogenic gas liquefaction. However, the current reliance on highly resource critical, heavy rare-earth-based compounds as magnetocaloric material makes global usage unsustainable. Here, we aim to mitigate this limitation through the utilization of a multicaloric cooling concept, which uses the external stimuli of isotropic pressure and magnetic field to tailor and induce magnetostructural phase transitions associated with large caloric effects. In this study, La0.7Ce0.3Fe11.6Si1.4 is used as a nontoxic, low-cost, low-criticality multiferroic material to explore the potential, challenges, and peculiarities of multicaloric cryocooling, achieving maximum isothermal entropy changes up to -28 J (kg K)-1 in the temperature range from 190 K down to 30 K. Thus, the multicaloric cooling approach offers an additional degree of freedom to tailor the phase transition properties and may lead to energy-efficient and environmentally friendly gas liquefaction based on designed-for-purpose, noncritical multiferroic materials.

Robust magnetism and crystal structure in Dirac semimetal EuMnBi2under high pressure.

Dirac materials offer exciting opportunities to explore low-energy carrier dynamics and novel physical phenomena, especially their interaction with magnetism. In this context, this work focuses on studies of pressure control on the magnetic state of EuMnBi2, a representative magnetic Dirac semimetal, through time-domain synchrotron Mössbauer spectroscopy in151Eu. Contrary to the previous report that the antiferromagnetic order is suppressed by pressure above 4 GPa, we have observed robust magnetic order up to 33.1 GPa. Synchrotron-based x-ray diffraction experiment on a pure EuMnBi2sample shows that the tetragonal crystal lattice remains stable up to at least 31.7 GPa.

Strong enhancement of magnetic ordering temperature and structural/valence transitions in EuPd3S4 under high pressure.

We present a comprehensive study of the inhomogeneous mixed-valence compound, EuPd3S4, by electrical transport, X-ray diffraction, time-domain 151Eu synchrotron Mössbauer spectroscopy, and X-ray absorption spectroscopy measurements under high pressure. Electrical transport measurements show that the antiferromagnetic ordering temperature, TN, increases rapidly from 2.8 K at ambient pressure to 23.5 K at ~19 GPa and plateaus between ~19 and ~29 GPa after which no anomaly associated with TN is detected. A pressure-induced first-order structural transition from cubic to tetragonal is observed, with a rather broad coexistence region (~20 GPa to ~30 GPa) that corresponds to the TN plateau. Mössbauer spectroscopy measurements show a clear valence transition from approximately 50:50 Eu2+:Eu3+ to fully Eu3+ at ~28 GPa, consistent with the vanishing of the magnetic order at the same pressure. X-ray absorption data show a transition to a fully trivalent state at a similar pressure. Our results show that pressure first greatly enhances TN, most likely via enhanced hybridization between the Eu 4f states and the conduction band, and then, second, causes a structural phase transition that coincides with the conversion of the europium to a fully trivalent state.

Minimally invasive colectomies can be performed with similar outcomes to open counterparts for colorectal cancer emergencies: a propensity score matching analysis utilizing ACS-NSQIP.

PURPOSE: The safety and feasibility of minimally invasive surgery (MIS) in the setting of colorectal cancer emergencies have been debated. We sought to compare postoperative outcomes of MIS with open techniques in the setting of colorectal cancer emergencies from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. METHODS: We included patients undergoing colectomy for colorectal cancer emergency between 2012 and 2019 "2012-2019" from the ACS-NSQIP dataset. We compared short-term morbidity, mortality, short-term oncological outcomes, and secondary outcomes for MIS vs open colectomies using propensity score matching. We then evaluated the trends of MIS versus open colectomies using linear regression analysis. RESULTS: We examined a total of 5544 patients (open n = 4070; MIS n = 1474) and included 1352 patients for our postoperative outcome analyses after propensity score matching 1:1 (open n = 676; MIS n = 676). Within the matched cohort, mortality was significantly higher in the open group (open 6.95% vs MIS 3.99%, OR 1.8, p = 0.023). Anastomotic leak rates were comparable between the  two groups (open 4.46% vs MIS 4.02%, OR 1.12, p = 0.787). Pulmonary complications were significantly higher after open surgery (open 10.06% vs MIS 4.73%, OR 2.25, p < 0.001). Rates of ileus were significantly higher amongst open patients (open 29.08% vs MIS 19.94%, p < 0.001). Patients stayed on average 1 day longer in the hospital after open surgery (p < 0.001). Rates of MIS for early tumors (N0 and T1/T2, n = 289) did not significantly change over 7 years (p = 0.597, rate = - 0.065%/year); however, utilization of MIS for late tumors (N1 or T3/T4, n = 4359) increased by 2.06% per year (p < 0.001). CONCLUSIONS: This study demonstrates that MIS was associated with superior postoperative outcomes compared to open surgery without compromising oncological outcomes in patients undergoing emergency colectomy for colon cancer. Within the matched cohort, MIS was associated with lower rates of mortality, pulmonary complications, ileus, and shorter postoperative length of stay.

Spin polarization assisted facile C-H activation by an S = 1 iron(iv)-bisimido complex: a comprehensive spectroscopic and theoretical investigation.

High valent iron terminal imido species (Fe[double bond, length as m-dash]NR) have been shown to be key reactive intermediates in C-H functionalization. However, the detailed structure-reactivity relationship in Fe[double bond, length as m-dash]NR species derived from studies of structurally well-characterized high-valent Fe[double bond, length as m-dash]NR complexes are still scarce, and the impact of imido N-substituents (electron-donating vs. electron-withdrawing) on their electronic structures and reactivities has not been thoroughly explored. In this study, we report spectroscopic and computational studies on a rare S = 1 iron(iv)-bisimido complex featuring trifluoromethyl groups on the imido N-substituents, [(IPr)Fe(NC(CF3)2Ph)2] (2), and two closely related S = 0 congeners bearing alkyl and aryl substituents, [(IPr)Fe(NC(CMe3)2Ph)2] (3) and [(IPr)Fe(NDipp)2] (1), respectively. Compared with 1 and 3, 2 exhibits a decreased Fe[double bond, length as m-dash]NR bond covalency due to the electron-withdrawing and the steric effect of the N-substituents, which further leads to a pseudo doubly degenerate ground electronic structure and spin polarization induced ß spin density on the imido nitrogens. This unique electronic structure, which differs from those of the well-studied Fe(iv)-oxido complexes and many previously reported Fe(iv)-imido complexes, provides both kinetic and thermodynamic advantages for facile C-H activation, compared to the S = 0 counterparts.

Fillers around the nose.

OBJECTIVE: The aim of this paper is to investigate the efficacy of filler applications which were evaluated in terms of nasal deformity and quality of life of the patients, and to review the fillers around the nose. PATIENTS AND METHODS: Forty patients who underwent filler application were included into the study and were divided into Group 1 (Deep Radix), Group 2 (Minor irregularities due to rhinoplasty), Group 3 (Shallow dorsum) and Group 4 (Dorsal irregularity). There were 10 patients in each of the groups. In all groups, nasal deformity score was evaluated with a 1 to 5 scale as following: 1- No deformity, 2- Hardly visible deformity, 3- Visible deformity, 4- Moderate deformity, 5- Apparent deformity. Quality of life was evaluated by a 1 to 10 scale, 1 showing very low and 10 showing very high. RESULTS: Our results showed that there were statistically significant improvements (decreased) in nasal deformity evaluation scores after the procedure compared to the before the procedure scores in Group 1 (Deep Radix), Group 3 (Shallow dorsum) and Group 4 (Dorsal irregularity) (p<0.05) However in Group 2 (Minor irregularities due to rhinoplasty), there were no significant differences between the nasal deformity evaluation scores after and before the procedure (p>0.05). For nasal deformity evaluation after the procedure, Group 1 (Deep Radix), Group 3 (Shallow dorsum) and Group 4 (Dorsal irregularity) scores were significantly lower (better) than Group 2 (Minor irregularities due to rhinoplasty) scores (padjusted <0.0125). In all four groups (Deep Radix, Minor irregularities due to rhinoplasty, Shallow dorsum, Dorsal irregularity), quality of life scores were significantly improved (increased) after the procedure compared to before the procedure (p<0.05). For Quality of life (VAS) before the procedure, Group 3 (Shallow dorsum) scores were significantly higher (improved, increased) than Group 1 (Deep Radix) and Group 4 (Dorsal irregularity) (padjusted <0.0125). CONCLUSIONS: Filler applications improved (decreased) nasal deformity evaluation scores and improved (increased) quality of life scores. Fillers can be applied for deep radix, minor irregularities due to rhinoplasty, shallow dorsum and dorsal irregularity. It is essential to choose carefully appropriate materials and procedures for patients to obtain optimum results.

Bromelain: a candidate to enhance wound healing after endonasal surgeries.

OBJECTIVE: In the present study, we investigated the topical bromelain's cytotoxic effects on mouse fibroblast NIH/3T3 cells via cell culture study. MATERIALS AND METHODS: In this cell culture study, Dulbecco's Modified Eagle Medium (DMEM) with fetal bovine serum (FBS, 10%) and penicillin/streptomycin (1%) was used as a cell growth medium for NIH/3T3 mouse fibroblast cells. MTT test was performed in 96-well plates seeded with NIH/3T3 cells 5x103/well and under standard cell culture conditions. Bromelain doses of 3.13 to 100 µM were administered to the wells and incubated for 24, 48, and 72 hours in the same cell culture conditions. For Confocal microscopic evaluation, NIH/3T3 cells were plated on cover slips in 6-well plates (105 cells/well) and treated with 100 µM concentration of bromelain for 24 h. Untreated cells were used as controls. RESULTS: MTT results showed that bromelain is not cytotoxic on mouse fibroblast NIH/3T3 cells. All three incubation times of 24, 48, and 72 hours bromelain initiated cell growth. A statistically significant rise in cell growth was detected in the only applied highest dose of 100 µM bromelain for all incubation times except for 24 hours. The nontoxic effect was further investigated by using confocal microscopy by applying the highest bromelain dose of 100 µM to NIH/3T3 mouse fibroblast cells. Confocal micrographs showed that bromelain did not change the morphology of mouse fibroblast cells at the incubation time of 24h. In untreated cells and bromelain-treated cells, the nucleus of NIH/3T3 cells was undamaged and compact, and the cytoskeleton was fusiform and non-fragmented. CONCLUSIONS: Bromelain is not cytotoxic on mouse fibroblast NIH/3T3 cells and enhances cell growth. If clinical trials will confirm this, it is possible that bromelain will be used topically in humans to enhance wound healing, in rhinosinusitis and chronic rhinosinusitis with nasal polyps and endonasal surgeries due to its anti-inflammatory effects.

Pressure effect on magnetism and valence in ferromagnetic superconductor Eu(Fe0.75Ru0.25)2As2.

Eu(Fe0.75Ru0.25)2As2is an intriguing system with unusual coexistence of superconductivity and ferromagnetism, providing a unique platform to study the nature of such coexistence. To establish a magnetic phase diagram, time-domain synchrotron Mössbauer experiments in151Eu have been performed on a single crystalline Eu(Fe0.75Ru0.25)2As2sample under hydrostatic pressures and at low temperatures. Upon compression the magnetic ordering temperature increases sharply from 20 K at ambient pressure, reaching ∼49 K at 10.1 GPa. With further compression, the magnetic order is suppressed and eventually collapses. Isomer shift values from Mössbauer measurements and x-ray absorption spectroscopy data at EuL3edge show that pressure drives Eu ions to a homogeneous intermediate valence state with mean valence of ∼2.4 at 27.4 GPa, possibly responsible for the suppression of magnetism. Synchrotron powder x-ray diffraction experiment reveals a tetragonal to collapsed-tetragonal structural transition around 5 GPa, a lower transition pressure than in the parent compound. These results provide guidance to further work investigating the interplay of superconductivity and magnetism.

Signature of Many-Body Localization of Phonons in Strongly Disordered Superlattices.

Many-body localization (MBL) has attracted significant attention because of its immunity to thermalization, role in logarithmic entanglement entropy growth, and opportunities to reach exotic quantum orders. However, experimental realization of MBL in solid-state systems has remained challenging. Here, we report evidence of a possible phonon MBL phase in disordered GaAs/AlAs superlattices. Through grazing-incidence inelastic X-ray scattering, we observe a strong deviation of the phonon population from equilibrium in samples doped with ErAs nanodots at low temperature, signaling a departure from thermalization. This behavior occurs within finite phonon energy and wavevector windows, suggesting a localization-thermalization crossover. We support our observation by proposing a theoretical model for the effective phonon Hamiltonian in disordered superlattices, and showing that it can be mapped exactly to a disordered 1D Bose-Hubbard model with a known MBL phase. Our work provides momentum-resolved experimental evidence of phonon localization, extending the scope of MBL to disordered solid-state systems.

Persistent polyamorphism in the chiton tooth: From a new biomineral to inks for additive manufacturing.

Engineering structures that bridge between elements with disparate mechanical properties are a significant challenge. Organisms reap synergy by creating complex shapes that are intricately graded. For instance, the wear-resistant cusp of the chiton radula tooth works in concert with progressively softer microarchitectural units as the mollusk grazes on and erodes rock. Herein, we focus on the stylus that connects the ultrahard and stiff tooth head to the flexible radula membrane. Using techniques that are especially suited to probe the rich chemistry of iron at high spatial resolution, in particular synchrotron Mössbauer and X-ray absorption spectroscopy, we find that the upper stylus of Cryptochiton stelleri is in fact a mineralized tissue. Remarkably, the inorganic phase is nano disperse santabarbaraite, an amorphous ferric hydroxyphosphate that has not been observed as a biomineral. The presence of two persistent polyamorphic phases, amorphous ferric phosphate and santabarbaraite, in close proximity, is a unique aspect that demonstrates the level of control over phase transformations in C. stelleri dentition. The stylus is a highly graded material in that its mineral content and mechanical properties vary by a factor of 3 to 8 over distances of a few hundred micrometers, seamlessly bridging between the soft radula and the hard tooth head. The use of amorphous phases that are low in iron and high in water content may be key to increasing the specific strength of the stylus. Finally, we show that we can distill these insights into design criteria for inks for additive manufacturing of highly tunable chitosan-based composites.

Effects of Noncovalent Interactions on High-Spin Fe(IV)-Oxido Complexes.

High-valent nonheme FeIV-oxido species are key intermediates in biological oxidation, and their properties are proposed to be influenced by the unique microenvironments present in protein active sites. Microenvironments are regulated by noncovalent interactions, such as hydrogen bonds (H-bonds) and electrostatic interactions; however, there is little quantitative information about how these interactions affect crucial properties of high valent metal-oxido complexes. To address this knowledge gap, we introduced a series of FeIV-oxido complexes that have the same S = 2 spin ground state as those found in nature and then systematically probed the effects of noncovalent interactions on their electronic, structural, and vibrational properties. The key design feature that provides access to these complexes is the new tripodal ligand [poat]3-, which contains phosphinic amido groups. An important structural aspect of [FeIVpoat(O)]- is the inclusion of an auxiliary site capable of binding a Lewis acid (LAII); we used this unique feature to further modulate the electrostatic environment around the Fe-oxido unit. Experimentally, studies confirmed that H-bonds and LAII s can interact directly with the oxido ligand in FeIV-oxido complexes, which weakens the Fe═O bond and has an impact on the electronic structure. We found that relatively large vibrational changes in the Fe-oxido unit correlate with small structural changes that could be difficult to measure, especially within a protein active site. Our work demonstrates the important role of noncovalent interactions on the properties of metal complexes, and that these interactions need to be considered when developing effective oxidants.

Drainless resection of the submandibular gland with facial vessel preservation: A comparative study.

OBJECTIVE: Resection of the submandibular gland (SMG) is a common surgery and many surgeons leave a drainage system in the surgical field. However, surgical drain may increase risk of complication and related prolonged hospitalization time. The purpose of this study was to investigate the safety of SMG resection without any surgical drainage system. METHODS: This retrospective trial on SMG surgery was conducted between 2016 and 2019. Patients were assigned into one of two main groups: surgical drain (+) (n=20) and surgical drain (-) (n=17). All surgical procedures were done via a standardized surgical technique. Facial vessels were dissected and only glandular branches were ligated. Also, non-identification method was applied for marginal mandibular nerve (MMN) protecting. In surgical drain (-) group, before the wound closure, oxidized regenerated cellulose (ORC) was placed in the surgical field. Moreover, a closed suction drain was inserted in surgical drain (+) group. RESULTS: A total of 37 SMG resections were performed: 15 patients had sialolithiasis, 14 patients had pleomorphic adenoma and 8 patients had chronic sialadenitis. There were 20 women (54%) and 17 men (46%), with an age range of 23-70 years. No major complications were observed in surgical drain (-) group. There were two cases with minor complications. One patient (5.8%) occurred transient paralysis of the MMN. Other patient developed seroma and it was easily managed with repeated punctures. ORC related allergic reaction or adverse incident were not detected in any of the patients. On the other hand, in surgical drain (+) group, 2 patients (10%) developed a hematoma on the first postoperative day and local wound infection was detected in 4 patients (20%). We found that the surgical drain usage was related to prolonged hospitalization, worse wound healing and problems with scarring. CONCLUSION: Our findings provide evidence for the safe drainless resection of the SMG using ORC. It may be possible to prevent all of these undesirable conditions by a surgery which performed without drain insertion.

Terminal Hydride Species in [FeFe]-Hydrogenases Are Vibrationally Coupled to the Active Site Environment.

A combination of nuclear resonance vibrational spectroscopy (NRVS), FTIR spectroscopy, and DFT calculations was used to observe and characterize Fe-H/D bending modes in CrHydA1 [FeFe]-hydrogenase Cys-to-Ser variant C169S. Mutagenesis of cysteine to serine at position 169 changes the functional group adjacent to the H-cluster from a -SH to -OH, thus altering the proton transfer pathway. The catalytic activity of C169S is significantly reduced compared to that of native CrHydA1, presumably owing to less efficient proton transfer to the H-cluster. This mutation enabled effective capture of a hydride/deuteride intermediate and facilitated direct detection of the Fe-H/D normal modes. We observed a significant shift to higher frequency in an Fe-H bending mode of the C169S variant, as compared to previous findings with reconstituted native and oxadithiolate (ODT)-substituted CrHydA1. On the basis of DFT calculations, we propose that this shift is caused by the stronger interaction of the -OH group of C169S with the bridgehead -NH- moiety of the active site, as compared to that of the -SH group of C169 in the native enzyme.

Aqueous Superparamagnetic Magnetite Dispersions with Ultrahigh Initial Magnetic Susceptibilities.

Superparamagnetic nanoparticles with a high initial magnetic susceptibility χo are of great interest in a wide variety of chemical, biomedical, electronic, and subsurface energy applications. In order to achieve the theoretically predicted increase in χo with the cube of the magnetic diameter, new synthetic techniques are needed to control the crystal structure, particularly for magnetite nanoparticles larger than 10 nm. Aqueous magnetite dispersions (Fe3O4) with a χo of 3.3 (dimensionless SI units) at 1.9 vol %, over 3- to 5-fold greater than those reported previously, were produced in a one-pot synthesis at 210 °C and ambient pressure via thermal decomposition of Fe(II) acetate in triethylene glycol (TEG). The rapid nucleation and focused growth with an unusually high precursor-to-solvent molar ratio of 1:12 led to primary particles with a volume average diameter of 16 nm and low polydispersity according to TEM. The morphology was a mixture of stoichiometric and substoichiometric magnetite according to X-ray diffraction (XRD) and Mössbauer spectroscopy. The increase in χo with the cube of magnetic diameter as well as a saturation magnetization approaching the theoretical limit may be attributed to the highly crystalline structure and very small nonmagnetic layer (∼1 nm) with disordered spin orientation on the surface.

Pyriform aperture enlargement in all aspects.

BACKGROUND: The pyriform aperture comprises the central area of facial bone structure. It is formed by the free corners of the nasal bone and the frontal processes of the maxillae, which articulate with each other at the nasomaxillary suture lines. Congenital nasal pyriform aperture stenosis might be linked to various craniofacial problems. This review presents all aspects of pyriform aperture stenosis and enlargement. METHODS: A literature search was conducted. Pyriform aperture definition, nasal development, congenital nasal pyriform aperture stenosis and pyriform aperture enlargement were reviewed. RESULTS: One of the most common abnormalities is holoprosencephaly, which is a midline developmental deficiency that may also be present in combination with facial clefting. The aetiology of nasal pyriform aperture stenosis remains unclear. When diagnosed, the choice of treatment is between non-surgical and operative methods, depending on the seriousness of the problem. Provided the sufferer can maintain a secure air passage with the help of specialised medical procedures and respiratory tract adjuvants, operative therapy may be delayed. CONCLUSION: The operative outcomes are extremely good, and the prognosis relies mainly on coexisting neural and endocrine problems. This paper evaluates the nasal pyriform aperture in detail.

Iron isotopic fractionation between silicate mantle and metallic core at high pressure.

The +0.1‰ elevated 56Fe/54Fe ratio of terrestrial basalts relative to chondrites was proposed to be a fingerprint of core-mantle segregation. However, the extent of iron isotopic fractionation between molten metal and silicate under high pressure-temperature conditions is poorly known. Here we show that iron forms chemical bonds of similar strengths in basaltic glasses and iron-rich alloys, even at high pressure. From the measured mean force constants of iron bonds, we calculate an equilibrium iron isotope fractionation between silicate and iron under core formation conditions in Earth of ∼0-0.02‰, which is small relative to the +0.1‰ shift of terrestrial basalts. This result is unaffected by small amounts of nickel and candidate core-forming light elements, as the isotopic shifts associated with such alloying are small. This study suggests that the variability in iron isotopic composition in planetary objects cannot be due to core formation.