Fastener holes are among the most common natural stress concentrators in metal structures. The life cycles of various structural elements, such as those in aircraft structures, automobiles, and rail-end bolt joints are limited by fatigue damage around the holes. An effective approach to delay the formation and growth of fatigue macrocracks is to introduce residual hoop compressive stresses around the holes. Two methods have become established in the prestressing of fastener holes in aircraft components: split sleeve and split mandrel, which implement one-sided processes. The common disadvantage of both methods is the complex procedure due to the need for high accuracy of the initial holes. This article presents a new modified split mandrel method providing the same tightness (interference fit) with a wide tolerance of the pre-drilled hole diameters reducing the number of technological cycle steps and production costs. То implement the new method, a functionally connected tool and a device with a hydraulic drive were developed. An extensive experimental study of 2024-T3 AA specimens was carried out to evaluate the effectiveness of the method under a high scattering of the pre-drilled holes. The new method provided a deep zone of residual hoop compressive stresses on both faces of the specimens after cold working and after hole final reaming. The removal of a plastically deformed layer around the hole of suitable thickness during the final reaming decreased the axial gradient of residual hoop stress distribution. Fatigue tests on a tensile pulsating cycle verified the effectiveness of the modified split mandrel method to significantly increase the fatigue life by 6.6 times based on cycle fatigue strength compared to the conventional case of machining the holes. The obtained S-N curves for three groups of samples with initial hole diameters of 8.0, 8.1, and 8.2 mm which were cold worked with the same tightness of 0.32 mm and final reamed, aligned well indicating that the new method can provide constant fatigue strength for a given stress amplitude.

Background: Low T3 syndrome occurs frequently in patients with sepsis. Type 3 deiodinase (Dio3) is present in immune cells but there is no description of its presence in this patients. Here we aimed to determine the prognostic impact of thyroid hormones levels (TH) measured on ICU admission on mortality and on evolution to chronic critical illness (CCI) and the presence of D3 in white cells. Methods: Prospective cohort study with a follow-up for 28 days or deceased. Results: Low T3 levels at admission were present in 86.5% of the patients. Dio3 was 55% induced in immune cells. The cut-off value of 60 pg/mL for T3 displayed a sensitivity and specificity of 81% and 64% for predicting death, odds ratio of 4.89. Lower T3 yielded an area under the receiver operating characteristic curve of 0.76 and 0.75 for mortality and evolution to CCI, respectively, thus displaying better performance than commonly used prognostic scores. Conclusions: We advance in the pathophysiology of low T3 showing induced D3 in immune cells during sepsis. Low T3 levels independently predicted a progression to CCI and mortality within 28 days in sepsis and septic shock.

The silane (3-Aminopropyl)triethoxysilane (APTES), possesses one terminal amine group and three ethoxy groups extending from each silicon atom, serving as a crucial interface adherent between organic and inorganic materials. In corrosion prevention, APTES is frequently employed as a primer, with subsequent topcoat as an extra protective layer. This topcoat is particularly useful in covering sites where APTES may exhibit poor bonding, such as those involving Cu or Cu-rich alloying elements. In our study, we applied a thin layer of APTES to cleaned AA2024-T3 samples using concentrated vapor deposition, followed by spin-coating with a diluted PS/acetone solution. Through combinatorial experimentation, we investigated the impact of APTES on the corrosion resistance of the coating system on AA2024-T3. Our findings indicate that a higher surface energy of the APTES primer contributes to better corrosion resistance in the overall coating system. This improvement can be attributed to enhanced wettability achieved by the PS/acetone solution on the cured APTES primer, leading to a more uniform coverage of the dried PS topcoat. Additionally, our research revealed that, in the early stages of exposure to the corrosion solution, a thinner APTES primer enhances protection against corrosion. This effect is attributed to hydrolytic stability mechanisms, and the interactions between hydrolyzation/condensation in soaked APTES and the dissolution of naturally formed aluminum oxide pre-existing in the bare samples. Finally, we observed that an APTES primer subjected to additional heat treatment before topcoating exhibits superior performance in corrosion resistance.

Oxidative stress (OS) is reported in several chronic diseases. Extra-cellular superoxide dismutase (ec-SOD) catalyzes the dismutation of superoxide anion with a protective role on endothelial cells. In chronic kidney diseases (CKD), OS and thyroid dysfunction (low T3 syndrome) are fre-quently present, but their relationship has not been investigated. This cohort study evaluated ec-SOD activity in CKD patients during haemodialysis, divided into: “acute hemodialytic pa-tients” (AH, 1-3 months of treatment) and “chronic hemodialytic patients” (CH, treated for a longer period). We also evaluated plasmatic total antioxidant capacity (TAC) and the relation-ships with thyroid hormones. Two basal samples (“basal 1”, 3 days after the last dialysis and “basal 2”, 2 days after the last dialysis) were collected. On the same day of basal 2, a sample was collected 5 and 10 min after the standard heparin dose and at the end of the procedure. The ec-SOD values were significantly higher in CH vs AH in all determinations. Moreover, they pre-sented lower TAC values. Dividing CH patients into two subgroups according to fT3 levels (nor-mal or low) we found significantly lower ec-SOD values in the group with low fT3 at basal, 5 and 10 min samples. Finally, a significant correlation was observed between fT3 and ec-SOD in the basal 1 samples. These data, confirming OS and low T3 syndrome in CKD, suggest that low fT3 concentrations can influence ec-SOD activity and therefore contribute to possible endothelial oxi-dative damage in such a situation.

The nonlocality (superdiffusion) of turbulence is expressed in the empiric Richardson t3 scaling law for the mean square of the mutual separation of a pair of particles in a fluid or gaseous medium. The development of the theory of nonlocality of various processes in physics and other sciences based on the concept of Lévy flights resulted in the idea of Shlesinger and colleagues about the possibility of describing the nonlocality of turbulence using a linear integro-differential equation with a slowly falling kernel. The close approach developed by us made it possible to establish the closeness of the superdiffusion parameter of plasma density fluctuations moving across a strong magnetic field in a tokamak to the Richardson law. In this paper, we show the possibility of a universal description of the characteristics of nonlocality of transfer in a stochastic medium (including turbulence of gases and fluids) using the Biberman-Holstein approach to the transfer of excitation of a medium by photons, generalized to take into account the finiteness of the velocity of excitation carriers. This approach enables us to propose a scaling that generalizes Richardson's t3 scaling law to the combined regime of Lévy flights and Lévy walks.

There is a have been positive correlations between the existence of type 2 diabetes mellitus (T2DM) and the development of thyroid disorders. Prediabetes is a progressive state of moderate insulin resistance that often precedes the onset of type 2 diabetes mellitus (TT2DM) however the association between prediabetes and thyroid function is unknown. This study assessed changes in markers of thyroid function in diet-induced prediabetes. 12 male Sprague Dawley rats were randomly allocated into two groups. Rats in the non-prediabetic (NPD) group were fed a standard rat diet while rats in the prediabetic (PD) were fed a high-fat high carbohydrate diet for 20 weeks to induce prediabetes. Thereafter, fasting blood glucose levels were measured. Plasma samples were assessed for triiodothyronine (T3), thyroxine (T4), thyroxine peroxidase (TPO) antibody, insulin and glycated haemoglobin (HbA1c) concentrations. The elevated blood glucose, HbA1c and plasma insulin levels coincided with increased T3 and reduced T4 levels in the PD group when compared to the NPD group. There was also an increase in the concentration of TPO antibodies in the PD group. Additionally, there was a significant correlation between the thyroid hormone concentrations and HbA1c levels. In conclusion, these results indicated that there is a positive association between thyroid dysfunction and diet-induced prediabetes.