Сорбционни характеристики на брашнени смеси обогатени с брашно от гроздови семки от български и френски суровини

The aim of the present scientific research is to study the moisture sorption characteristics of flour mixtures of Bulgarian and French origin. The mixtures are enriched with grape seeds flour in its being an enological residue. Equilibrium moisture content are determined at three different temperatures at 10 °C, 25 °C and 40°C through the standard static gravimetric method in the compulsory presence of water activity within the range from 0.1 to 0.9. The obtained adsorption and desorption isotherms have an S-shape profile i.e. they are from the IInd class typical of the majority of food products. The results confirm a regularity that the sorption capacity decreases with increasing of the temperature in the presence of constant water activity which is valid for both products as well as for both processes (adsorption and desorption). The mathematical modified models of Chung–Pfost, Oswin, Halsey and Henderson are evaluated for the description of the sorption data. The monolayer moisture content (MMC) of flour mixtures is calculated through the linearization of Brunauer-Emmett-Teller equation. For the Bulgarian mixture the values varied from 2.54% to 4.29% and for the French mixture – from 2.67% to 4.13%Настоящите научни изследвания се заемат с изследване на сорбционните характеристики на брашнени смеси от български и френски произход. Смесите са обогатени с брашно от гроздови семки в качеството си на енологичен отпадък, съответно от български и френски произход. Равновесното влагосъдържание се определя при три различни температури 10°C, 25°C и 40 ° C чрез стандартен статичен гравиметричен метод и водна активност в диапазона от 0,1 до 0,9. Получените изотерми имат S-образен характер, т.е. те са от II тип, типичен за повечето хранителни продукти. Резултатите потвърждават закономерността, че сорбционният капацитет намалява с повишаването на температурата в условията на константна водна активност, валидна и за двата продукта, както и при двата процеса (адсорбция и десорбция). За описание на сорбционните изотерми се използват математическите модифицирани модели на Chung – Pfost, Oswin, Halsey и Henderson. Мономолекулната влажност на брашнените смеси се изчислява чрез линеаризация на уравнението на БрунауерЕмет-Телер. За българската смес стойностите варират от 2,54% до 4,29%, а за френската смес - варират от 2,67% до 4,13

Nucleation activity of glass fibers towards iPP evaluated by DSC and polarizing light microscopy

Nucleation activity of unsized and differently sized glass fibers during the crystallization of polypropylene from melt was investigated by polarizing light microscopy and DSC. Depending on the type of surface treatment, glass fibers were shown to exhibit different nucleating effects, evaluated by induction time of crystallization, crystallization onset temperature as well as half-time of crystallization in model composites with 50% wt glass fibers. Predominant nucleation activity was found for glass fibers sized with polypropylene compatible dispersion containing polyurethanes. However, according to the results of DSC measurements, unsized glass fibers slightly depressed the nucleation of polypropylene. Using the approach of Dobreva et al., the activity of the fibers towards heterogeneous nucleation during nonisothermal crystallization was evaluated

Utilization of recycled polymer matrices for production of eco-composites

Abstract: One of the big new areas of development of the advanced composite materials is in combining natural fi bers with thermoplastics for producing lightweight, environmentally friendly, cost-effective composite material. The aim of this work is to show the possibilities of recycling and reuse of thermoplastic polymer matrices with rice hulls (RH) and kenaf fi bres (KF) using the conventional techniques, extrusion and compression moulding. The matrices (polypropylene (PP) and poly(lactic) acid (PLA) ) were recycled one and two times and the fi bers/fi ller were compounded with recycled matrix. The processing and material properties have been studied on the composites with recycled matrix and compared to the composites with virgin matrix. Characterization of all composites includes mechanical, morphological and thermo-gravimetrical analysis. Тhe fl exural properties for PP recycled based composites were held close to the fl exural properties for composite based on neat PP, but for PLA recycled based composite the fl exural properties are decreased for about 50%. The thermal stability of recycled matrices based composites is very similar to the thermal stability of the composites with virgin matrix. SEM analysis has shown that the fi llers/fi bers are covered by the recycled polymer matrix, indicated on the satisfi ed durability of the recycled polymer matrices. The obtained results have shown that both polymer matrices (biodegradable and no degradable) could be recycled with acceptable mechanical properties and they can be successfully used for production of eco-composites. Keywords: eco-composites, polypropylene, poly(lactic acid), rice hulls, kenaf fi bers, extrusion compressio

Biocomposites based on poly(lactic acid) and kenaf fibers: effect of microfibrillated cellulose

In this work, the influence of microfibrillated cellulose (MFC) on the basic mechanical properties of PLA/kenaf fiber biocomposites has been studied. The addition of 5–15 % microfibrillated cellulose to a biocomposite premix has resulted in an increased glass transition temperature of the final product, produced by compression molding of previously melt-mixed composite components. The presence of MFC has influenced the interface-sensitive properties of the PLA/kenaf composite: at an optimal loading of 10 %, the interfacial energy release rate was increased by about 20 %. Moreover, flexural strength and modulus of the composites were also improved (from 34.8 MPa to 57.1 MPa and from 4.9 GPa to 5.8 GPa, respectively). Keywords: biocomposites; poly(lactic acid); kenaf fibers; microfibrillated cellulos

Хомоцистеинот – ризик фактор и предиктор во појавата на васкуларните компликации кај пациентите со дијабетес мелитус тип 2

BACKGROUND: Homocysteine (HCY) is a sulphur containing amino acid. The entire amount of homocysteine in the body is formed through the cycle of methylation of the amino acid methionine, as the primary and only source of homocysteine. The plasma free HCY is only 1%, while 70% is bound to albumin. The metabolism of HCY involves three enzymes: methionine synthase (MS) methylenetetrahydrofolate reductase (MTHFR), cystathionine B synthase (CBS) and the vitamins B6, B12 and folic acid as cofactors of these enzymes. In case of metabolic disturbance of the metabolism of HCY due to enzymatic defect or because of lack of intracellular cofactor, HCY accumulates in the cells, after which it is excreted from the cells and its plasma levels rise. AIM: The purpose of this study is to obtain data that would prove the correlation of plasma homocysteine regarding the etiology of the microvascular and macrovascular complications of diabetes and the possibility of its use as an early predictor in the diagnosis of vascular complications in patients with diabetes mellitus. METHODS: This paper is a retrospective-prospective study conducted at the Clinic for Endocrinology, Diabetes and Metabolic Diseases in Skopje. The study have included 80 patients with diabetes mellitus 2. Patients who are recruited were divided into two groups: 50 patients diagnosed with vascular complications and a group of 30 patients without associated complications, which will be the control group. The test group of patients will be made up of patients with type 2 diabetes mellitus, with confirmed diagnosis and treated with insulin and oral treatment. RESULTS: From the preliminary results of the microvascular complications the most frequent and statistically significant is the prevalence of the nephropathy with 32%. Retinopathy was represented with 29 % and microalbuminuria was detected in 27.5% of the patients. Among the macrovascular complications 31 % of the patients were diagnosed with arterial hypertension and 12.50% with peripheral arterial diseases. In the present study higher levels of homocysteine were detected in group of diabetic subjects with microvascular and macrovascular complications comparing to control group of patients where no complications were diagnosed and levels of homocysteine were among reference ranges. CONCLUSION: Hiperhomocisteinemia represents a risk factor in etiology of chronic complications in patients with diabetes mellitus type 2. However, further research would provide clear evidence of the impact of increased levels of homocysteine and its role in damage to the endothelium of blood vessels and the emergence of long-term vascular complications.ОСНОВА: Хомоцистеинот (Нсу) е амино киселина која содржи сулфур. Целото количество на хомоцистеин во организмот се формира преку циклусот на метилција од аминокиселината метионин, како основен и единствен извор на хомоцистеин. Во плазмата Нсу се наоѓа слободен само 1%, додека 70% се наоѓа врзан за албумините. Во метаболизмот на Нсу се инволвирани три ензими: метионин синтаза (МС), метилентетрихидрафолат редуктаза (МТХФР), цистатионин Б сентитаза (ЦБС) како и витамините B6, B12 и фолната киселина, како кофактори на овие ензими. Во случај на нарушување на метаболизмот на хомоцистеинот поради ензимски дефект или поради недостиг на некој интрацелуларен кофактор, доаѓа до акумулирање на Нсу во клетката и потоа до негово екскретирање и зголемување на нивоата во циркулацијата. ЦЕЛ: Целта на ова истражување е да се добијат податоци со кои би се докажала корелацијата на плазма хомоцистеинот во однос на етиологијата на микроваскуларните и макроваскуларните комликации како и можноста за негова употреба како ран предиктор во дијагностиката на васкуларните компликации кај пациентите со дијабетес мелитус. МЕТОДИ: Трудот претставува ретроспективно-проспективно истражување кое се одвиваше на клиниката за ендокринологија и болести на метаболизмот во Скопје. Студијата вклучи 80 пациенти со дијабетес мелитус 2. Регрутираните пациенти беа поделени во две групи: 50 пациенти со дијагностицирани васкуларни компликации и група од 30 пациенти без придружни компликации, која воедно е и контролна група. РЕЗУЛТАТИ: Од обработката на податоците, помеѓу микроваскуларните компликации сигнификантно најзастапена беше нефропатијата со 32%, потоа ретинопатијата со 29% и микроалбуминуријата со 27.5%. Од макроваскуларните комликации сигнификантно и значајно најзастапени беа хипертензивната болест со процентуална застапеност од 31%, и периферната артериска болест со 12.50%. Високи вредности на хомоцистеин беа нотирани кај двете групите на пациенти со микроваскуларни и макроваскуларни компликации во однос на контролната група на пациенти, каде вредностите на хомоцистеин беа помеѓу нормалните граници. ЗАКЛУЧОК: Хиперхомоцистеинемијата претставува ризик фактор во етиологијата на хронични компликации кај пациентите со дијабетес мелитус тип 2. Сепак, потребни се понатамошни истражувања кои би дале јасни податоци за влијанието на зголемените нивоа на хомоцистеин и неговата улога во оштетувањето на ендотелот на крвните садови и појава на долготрајни васкуларни компликации

Isothermal crystallization of iPP in model glass‐fiber composites

: Isothermal crystallization of iPP in model glass-fiber composites is studied by DSC, and the basic energetic parameters of crystallization are determined. Unsized untreated and thermally treated glass fibers are used in model composites to determine the role of the surface on nucleation and crystallization processes. Thermally treated glass fibers are found to exhibit a predominant nucleating effect as compared to unsized untreated ones, and the crystallization proceeds faster, resulting in lower values for the half-time of crystallization (10–120 s). The energy of formation of a nuclei of critical dimensions at a given Tc is also lower, and it decreases as the content of the fibers in the composite increases. The surface free energy of folding, σe = 140 × 10−3 J/m2, was determined for iPP in the composite containing 50% glass fibers, while for pure iPP, σe = 170 × 10−3J/m2 was found