Role of Somatostatin Signalling in Neuroendocrine Tumours

Somatostatin (SST) is a small peptide that exerts inhibitory effects on a wide range of neuroendocrine cells. Due to the fact that somatostatin regulates cell growth and hormone secretion, somatostatin receptors (SSTRs) have become valuable targets for the treatment of different types of neuroendocrine tumours (NETs). NETs are a heterogeneous group of tumours that can develop in various parts of the body, including the digestive system, lungs, and pituitary. NETs are usually slow growing, but they are often diagnosed in advanced stages and can display aggressive behaviour. The mortality rate of NETs is not outstandingly increased compared to other malignant tumours, even in the metastatic setting. One of the intrinsic properties of NETs is the expression of SSTRs that serve as drug targets for SST analogues (SSAs), which can delay tumour progression and downregulate hormone overproduction. Additionally, in many NETs, it has been demonstrated that the SSTR expression level provides a prognostic value in predicting a therapeutic response. Furthermore, higher a SSTR expression correlates with a better survival rate in NET patients. In recent studies, other epigenetic regulators affecting SST signalling or SSA–mTOR inhibitor combination therapy in NETs have been considered as novel strategies for tumour control. In conclusion, SST signalling is a relevant regulator of NET functionality. Alongside classical SSA treatment regimens, future advanced therapies and treatment modalities are expected to improve the disease outcomes and overall health of NET patients.     

Selective treatment of lube fractions with phenol in the presence of surfactants

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 1, pp. 8–9, January, 1995.     

Increasing the Efficiency of Dewaxing in the Deoiling Stage

During selective treatment, the content of high–melting paraffins and naphthenes that crystallize from solution when the temperature is decreased increases significantly in lube oil cuts after removal of resins and asphaltenes and polycyclic hydrocarbons with short side chains. These hydrocarbons, which have a high melting point, are removed during dewaxing to obtain low-pour lube oil cuts.     

Limits of linear viscoelastic behavior of polymers

In the present study different approaches for determination of the limits of linear viscoelastic (LVE) behavior are considered on examples of some thermoplastic and thermosetting polymers. Stress or strain level, commonly considered as a limit of LVE behavior, are interrelated time-dependent functions strongly influenced by action of external factors. The concept of energy threshold has an advantage of combining into one physical function the effects of both stress and strain in initiating nonlinear behavior. The value of the stored deviatoric energy is considered as a limit of LVE behavior and is a material characteristic. The experimental data on tension at various constant strain rates and tensile creep at various stresses, temperatures, and moisture conditions are considered. It is proved for some polymers that LVE limits in stress-strain representation fall on a common curve that is an energy curve independent of time. Decrease of the test rate or growth of temperature or moisture content appears only in a shift down along the energy curve to the lower limit stresses and higher limit strains.     

Relationship between the residual and total strain from creep-recovery tests of polypropylene/multiwall carbon nanotube composites

An assessment of accumulated irreversible strains in polymer composites is a crucial element for controlling dimensional stability of structural components and their remnant life. The residual strains as functions of total creep strains are analyzed by example of creep-recovery data of polypropylene (PP)/multiwall carbon nanotube (MWCNT) composites. To cover wide range of strains, creep test regimes with different stresses, loading time, and number of cycles were applied. Totally, data of 62 single creep-recovery tests for 7 material compositions were used for analysis. A general empirical relationship between the residual and total creep strain is established and finely described by a power law. The residual strain increases with increasing stress and time of loading and decreases with growing amount of MWCNT. The total creep strain, which is implicitly related to stress, time, and sample specificity, determines the contribution of irreversible deformation. This fact overcomes data variability within one series of samples. Similar empirical relationships are obtained for 25 polymer composites from literature reinforced with different types and amount of fillers and tested under different temperatures. The empirical relationship can be used for an express assessment of residual strains accumulated in a long term by performing just a few short-term control tests.