NMR spectroscopy in combination with statistical methods was used to study vacuum residues and vacuum gas oils from 32 crude oils of different origin. Two chemometric metodes were applied. First- ly, principal component analysis on complete spectra was used to perform classification of samples and clear distinction between vacuum residues and vacuum light and heavy gas oils were obtained. To quanti- tatively predict the composition of asphaltenes, principal component regression models using areas of res- onance signals spaned by 11 frequency bins of the 1 H NMR spectra were build. The first 5 principal com- ponents accounted for more than 94 % of variations in the input data set and coefficient of determination for correlation between measured and predicted values was R 2 = 0.7421. Although this value is not signifi- cant, it shows the underlying linear dependence in the data. Pseudo two-dimensional DOSY NMR exper- iments were used to assess the composition and structural properties of asphaltenes in a selected crude oil and its vacuum residue on the basis of their different hydrodynamic behavior and translational diffusion coefficients. DOSY spectra showed the presence of several asphaltene aggregates differing in size and interactions they formed. The obtained results have shown that NMR techniques in combina- tion with chemometrics are very useful to analyze vacuum residues and vacuum gas oils. Furthermore, we expect that our ongoing investigation of asphaltenes from crude oils of different origin will elucidate in more details composition, structure and properties of these complex molecular systems.

Two new, accurate, precise, and sensitive spectrophotometric methods were developed for the assay of L-ascorbic acid in pharmaceutical preparations. The determination of L-ascorbic acid was based on its oxidation by potassium peroxymonosulfate (method A) and hydrogen peroxide in the presence of Cu(II) as a catalyst (method B). The molar absorptivities were found to be 1.48×10 and 1.06×10 L mol cm for methods A and B, respectively. Beer's law was obeyed in the concentration range of 0.65–11.20 μg mL for method A and 0.51–16.00 μg mL for method B. Other compounds commonly found in vitamin C and multivitamin products did not interfere with the determination of L-ascorbic acid.. The proposed methods were successfully applied for the determination of L-ascorbic acid in pharmaceutical formulations. The results obtained with the proposed methods showed good agreement with those given by the titrimetric method using iodine.

PurposeInterruptions in medical treatment such as dose delays, reductions, or stoppages can lead to suboptimal treatment of cancer. Knowing how and for whom symptom severity and symptom interference with activities of daily living (ADL) are associated with treatment interruptions can guide behavioral interventions for supportive care. The purpose of this analysis is to inform research and clinical practice by bringing attention to specific patient symptoms that may hinder dose completion.MethodsA secondary analysis of data collected in a randomized clinical trial (RCT) of reflexology for symptom management was performed. The trial enrolled women with advanced breast cancer undergoing treatment (N = 385). Outcome data were collected at baseline, weeks 5 and 11 using valid and reliable measures. Medical records provided data on treatment interruptions and metastasis. The association between alterations in medical treatment during the study period with symptom severity, symptom interference with ADLs, and metastatic status were tested using generalized estimating equation (GEE) models.ResultsThe relationship between dose delays and dose reductions and symptom severity was differential according to metastatic status, with the higher strength of association among women with distant metastasis compared to those with loco-regional disease (p = 0.02). The interaction of symptom interference and metastatic status was also significantly related to dose delays and reductions (p = 0.04). Severity of pain was a stronger predictor of dose delays or reductions among patients with distant metastasis compared to those with loco-regional disease (p < 0.01).ConclusionThe analysis highlights the importance of understanding symptom outcomes that impact research, practice, and treatment decisions.

For any given polynomial $f$ over the finite field $\mathbb{F}_q$ with degree at most $q-1$, we associate it with a $q\times q$ matrix $A(f)=(a_{ik})$ consisting of coefficients of its powers $(f(x))^k=\sum_{i=0}^{q-1}a_{ik} x^i$ modulo $x^q -x$ for $k=0,1,\ldots,q-1$. This matrix has some interesting properties such as $A(g\circ f)=A(f)A(g)$ where $(g\circ f)(x) = g(f(x))$ is the composition of the polynomial $g$ with the polynomial $f$. In particular, $A(f^{(k)})=(A(f))^k$ for any $k$-th composition $f^{(k)}$ of $f$ with $k \geq 0$. As a consequence, we prove that the rank of $A(f)$ gives the cardinality of the value set of $f$. Moreover, if $f$ is a permutation polynomial then the matrix associated with its inverse $A(f^{(-1)})=A(f)^{-1}=PA(f)P$ where $P$ is an antidiagonal permutation matrix. As an application, we study the period of a nonlinear congruential pseduorandom sequence $\bar{a} = \{a_0, a_1, a_2, ... \}$ generated by $a_n = f^{(n)}(a_0)$ with initial value $a_0$, in terms of the order of the associated matrix. Finally we show that $A(f)$ is diagonalizable in some extension field of $\mathbb{F}_q$ when $f$ is a permutation polynomial over $\mathbb{F}_q$.

In the countries with developed financial markets, unlike in Bosnia and Herzegovina (BiH) and other emerging market countries (EMCs) with the so called bank-centric financial systems, corporate bonds are a rather significant alternative to the usage of bank loans for financing the development needs of the real sector of the economy (corporate sector). The new architecture of world’s financial stability with Basel III as its integral part additionally emphasizes this importance for both banks and companies. Besides, in the countries with developed financial markets it is probably needless to mention the need for high quality debt securities. This is especially true due to the conditions of stronger institutional investors on the market, such as pension funds that can realistically be expected to become the leading financial institutions of the 21st century, and ever increasing need of institutional investors, funds in particular, for high quality forms of assets and portfolio diversification. In EMCs in which pension reforms have still not been completely implemented or completed, considering a drastic fall in the ratio of the insured based on contribution payment and the number of pensioners, the existing situation is almost non-sustainable. Therefore, the transformation of pension funds in accordance to the two or three pillar structure and the emergence of voluntary pension funds as financially powerful institutional investors have no alternative. Certainly, in terms of corporate bonds and their issue on the one hand, and investing in them on the other, in EMCs and thus also in BiH there are some important aspects to be observed when analyzing their influence on the decisions on financing or investing (liquidity, interest rate level, clarity and implementation of regulations, etc.).