Priprema nanokompozitnih filmova od polietilena niske gustoće i cinkovog oksida za produljenje trajnosti svježih jagoda

Strawberries have a very short post-harvest life mostly due to their relatively high water content, intense metabolic activity and susceptibility to microbial rot. Antimicrobial low-density polyethylene nanocomposite films containing ZnO nanoparticles at different mass fractions were prepared by melt mixing and followed by compression moulding using a hot press machine. Fresh strawberries were packed in nanocomposite films and stored at 4 °C. Their microbial stability, ascorbic acid content and titratable acidity were evaluated after 0, 4, 8, 12 and 16 days of storage. Microbial growth rate was significantly reduced up to 16 days as a result of the use of nanocomposite packaging material containing ZnO nanoparticles. By increasing the ZnO nanoparticle mass fraction to 5 %, the antimicrobial activity of the film increased. All packages containing the ZnO nanoparticles kept the microbial load of fresh strawberries below the level that affects shelf life (5 log CFU/g) up to 16 days. The lowest degradation of ascorbic acid content (6.55 mg per 100 g), and loss of acidity (0.68 %) were observed in packages containing 3 % of ZnO nanoparticles with 10 % polyethylene-grafted maleic anhydride.Jagode imaju vrlo kratak vijek trajanja zbog relativno velikog udjela vlage, pojačane metaboličke aktivnosti i podložnosti truljenju. Antimikrobni nanokompozitni filmovi pripremljeni su umješavanjem različitih masenih udjela nanočestica cinkovog oksida u polietilen niske gustoće te izravnim prešanjem u kalupu. Svježe su jagode pakirane u nanokompozitne filmove i uskladištene na 4 °C. Mikrobiološka stabilnost, udjel askorbinske kiseline i titracijska kiselost jagoda mjereni su na početku skladištenja te nakon 4, 8, 12 i 16 dana. U pakovinama od nanokompozitnog filma s česticama cinkovog oksida bitno je usporen rast mikroorganizama tijekom perioda skladištenja do 16 dana. Povećanjem masenog udjela nanočestica cinkovog oksida na 5 % povećao se i antimikrobni učinak filma. U svim pakovinama s nanočesticama cinkovog oksida broj je stanica mikroorganizama bio dovoljno malen (5 log CFU/g) da ne utječe na održivost jagoda tijekom 16 dana skladištenja. U pakovinama s 3 % nanočestica cinkovog oksida i 10 % polietilena modificiranog s maleinskim anhidridom najmanje se smanjio udjel askorbinske kiseline (za 6,55 mg u 100 g) te titracijska kiselost (za 0,68 %)

Numerical Analysis of Carbon Fiber Reinforced Plastic (CFRP) Shear Walls and Steel Strips under Cyclic Loads Using Finite Element Method

Reinforced concrete shear walls are the main elements of resistance against lateral loads in reinforced concrete structures. These walls should not only provide sufficient resistance but also provide sufficient ductility in order to avoid brittle fracture, particularly under strong seismic loads. However, many reinforced concrete shear walls need to be stabilized and reinforced due to various reasons such as changes in requirements of seismic regulations, weaknesses in design and execution, passage of time, damaging environmental factors, patch of rebar in plastic hinges and in some cases failures and weaknesses caused by previous earthquakes or explosion loads. Recently, Fiber Reinforced Polymer (FRP) components have been extensively and successfully used in seismic improvement. This study reinforces FRP reinforced concrete shear walls and steel strips. CFRP and steel strips are evaluated by different yield and ultimate strength. Numerical and experimental studies are done on walls with scale 1/2. These walls are exposed to cyclic loading. Hysteresis curves of force, drift and strain of FRP strips are reviewed in order to compare results of numerical work and laboratory results. Both numerical and laboratory results show that CFRP and steel strips increase resistance, capacity and ductility of the structure

First-principles study of hydrogen dynamics in monoclinic TiO

The existence of intrinsic vacancies in cubic (monoclinic) TiO suggests opportunity for hydrogen absorption, which was addressed in recent experiments. In the present work, based on first principle calculations, the preferences are studied for the hydrogen absorption sites and diffusion paths between them. The oxygen vacancies are found to be primary hydrogen traps with absorption energy of -2.87 eV. The plausible channels for hydrogen diffusion between adjacent vacancy sites (ordered in the monoclinic TiO structure) are compared with the help of calculations done with the nudge elastic band method. Several competitive channels are identified, with barrier heights varying from 2.87 to 3.71 eV, that is high enough to ensure relative stability of trapped hydrogen atoms at oxygen vacancy sites. Moreover, the possibility of adsorption of molecular hydrogen was tested and found improbable, in the sense that the H2 molecules penetrating the TiO crystal are easily dissociated (and released atoms tend to proceed towards oxygen vacancy sites). These results suggest that hydrogen may persist in oxygen vacancy sites up to high enough temperatures.Comment: updated and enlarged version, accepted for publication in Journal of Physical Chemistry C (June 2023

Cooperative End-to-end Congestion Control in Heterogeneous Wireless Networks

Sharing the resources of multiple wireless networks with overlapped coverage areas has a potential of improving the transmission throughput. However, in the existing frameworks, the improvement cannot be achieved in congestion scenarios because of independent congestion control procedures among the end-to-end paths. Although various network characteristics make the congestion control complex, this variety can be useful in congestion avoidance if the networks cooperate with each other. When congestion happens in an end-to-end path, it is inevitable to have a packet transmission rate less than the minimum requested rate due to congestion window size adjustments. Cooperation among networks can help to avoid this problem for better service quality. When congestion is predicted for one path, some of the on-going packets can be sent over other paths instead of the congested path. In this way, the traffic can be shifted from a congested network to others, and the overall transmission throughput does not degrade in a congestion scenario. However, cooperation is not always advantageous since the throughput of cooperative transmission in an uncongested scenario can be less than that of non-cooperative transmission due to cooperation costs such as cooperation setup time, additional signalling for cooperation, and out-of-order packet reception. In other words, a trade-off exists between congestion avoidance and cooperation cost. Thus, cooperation should be triggered only when it is beneficial according to congestion level measurements. In this research, our aim is to develop an efficient cooperative congestion control scheme for a heterogeneous wireless environment. To this end, a cooperative congestion control algorithm is proposed, in which the state of an end-to-end path is provided at the destination terminal by measuring the queuing delay and estimating the congestion level. The decision on when to start/stop cooperation is made based on the network characteristics, instantaneous traffic condition, and the requested quality of service (QoS). Simulation results demonstrate the throughput improvement of the proposed scheme over non-cooperative congestion control.1 yea

Evento de blanqueamiento masivo en la zona norte del Gofo Pérsico, 2012

Coral bleaching events due to elevated temperatures are increasing in both frequency and magnitude worldwide. Mass bleaching was recorded at five sites in the northern Persian Gulf during August and September 2012. Based on available seawater temperature data from field, satellite and previous studies, we suggest that the coral bleaching threshold temperature in the northern Persian Gulf is between 33.5 and 34°C, which is about 1.5 to 2.5°C lower than that in the southern part. To assess the bleaching effects, coral genera counted during 60-minute dives were categorized into four groups including healthy, slightly bleached ( 50% bleached tissue) and fully bleached colonies. The anomalously high sea surface temperature resulted in massive coral bleaching (~84% coral colonies affected). Acropora spp. colonies, which are known as the most vulnerable corals to thermal stress, were less affected by the bleaching than massive corals, such as Porites, which are among the most thermo-tolerant corals. Turbid waters, suggested as coral refugia against global warming, did not protect corals in this study since most affected corals were found in the most turbid waters. The 2012 bleaching in the northern Persian Gulf was relatively strong from the viewpoint of coral bleaching severity. Long-term monitoring is needed to understand the actual consequences of the bleaching event on the coral reefs and communities.Los eventos de blanqueamiento de corales están aumentando en frecuencia y magnitud debido al aumento de la temperatura en los océanos. En este trabajo se describe un evento de blanqueamiento masivo observado en seis localidades del norte del Golfo Pérsico entre Agosto y Septiembre de 2012. Los datos de temperatura disponibles, medidas in situ y observaciones de satélites de la temperatura de la superficie del mar, sugieren que la temperatura umbral que desencadena el blanqueo de coral en el norte del Golfo Pérsico corresponde a una temperatura de entre 33,5-34°C que es una temperatura entre 1.5 a 2.5°C inferior a la observada en las zonas más meridionales del Golfo Persico (35-36°C). Para la evaluación de los efectos de blanqueo sobre las comunidades de coral, se realizaron transectos de 60 minutos entre 0 y 6 m de profundidad. Durante las inmersiones cada colonia de coral se identificó a nivel de género y su estado se asignó a una de las siguientes categorías: no afectada, ligeramente afectada ( 50% del tejido blanqueado) y colonias totalmente afectadas (100% del tejido blanqueado). El análisis de los datos de temperatura permitió identificar una anomalía térmica durante el periodo de blanqueamiento que afectó a un 84% de las colonias censadas. Contrariamente a otros eventos de blanqueamiento analizados, las colonias de Acropora spp., que se encuentran entre las especies más vulnerables al estrés térmico, fueron menos afectadas que las especies de corales masivos como Porites spp. que normalmente presentan una gran resistencia al estrés térmico. Igualmente a pesar que la turbidez de las aguas ha sido señalada como un factor protector en el contexto del calentamiento global, en nuestro estudio observamos que las zonas más afectadas por el blanqueamiento presentaban las tasas de turbidez más elevadas. En conclusión el evento de blanqueamiento de 2012 observado en el norte del Golfo Pérsico afectó severamente a las comunidades de coral. El seguimiento a largo plazo de las comunidades de coral se presenta como una necesidad para comprender las consecuencias de los eventos de blanqueamiento

Purification and Characterization of Carrageenan Extracted from Persian Gulf Laurencia snyderiae Red Algae

Abstract   Background and Objective: Carrageenans can be found in a group of red algae called Carrageenophytes (Gigartinaceae, Solieriaceae, Hypneaceae and Furcellariaceae); howe-ver, this substance has not been investigated in Laurencia species. In this study, two native species of Laurencia within the Persian Gulf were investigated to extract carrageenans. Therefore, the major aims of this study included extraction, optimization and purification of carrageenans from Laurencia snyderiae, a native red algae of Persian Gulf. Material and Methods: Laurencia snyderiae and Laurencia papillosa were identified based on their morphological characteristics. An experimental design was carried out using Design Expert Software to produce and optimize extraction of semi-refined carrageenans. The software programmed 18 treatments based on temperature, boiling time and KOH concentration. Products of the treatments were prepared for rheometric analyses (viscosity measurements). Optimization was carried out using the software based on the maximum viscosity. Refined carrageenan efficiency was assessed using four extraction methods. Moreover, Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy spectra were compared. Laurencia snyderiae was selected for further inves-tigation. Results and Conclusion: Based on the rheometric analyses, a semi-refined carrageenan solution was identified as a non-Newtonian pseudo-plastic fluid. The optimum treatment was investigated for Laurencia snyderiae at 65 °C for 35 min at KOH concentration of 7% w/v. Results of these two analyses showed that the refined carrageenans from Laurencia snyderiae included the lambda type. The highest efficiency was achieved using dialysis method (37%). Based on the abundance of the Laurencia snyderiae on the Persian Gulf coasts in all seasons, further studies on carrageenan with higher purities enable use of these substance in various industries. Broader rheological studies can precisely assess characteristics of the investigated carrageenans. Conflict of interest: The authors declare no conflict of interest

Herbs with anti-lipid effects and their interactions with statins as a chemical anti- hyperlipidemia group drugs: A systematic review.

BACKGROUND The present systematic review aimed to express the clinical anti-lipid effects of different types of herbs, as well as described studied interactions between herbal remedies and prescribed drugs for hyperlipidemic patients which were based on in vitro experiments, animal studies, and empirical clinical experiences. METHODS For this systematic review, we explored 2183 published papers about herbal drugs interactions from November 1967 to August 2014, fulfilling eligibility criteria by searching in some databases such as Web of Science, Medline, Scopus, Embase, Cinahl, and the Cochrane database. The main keywords used for searching included: herbal medicine, herbs, statin, lipid, and herb-drug interaction. RESULTS Among published articles about herb-drug interactions, 185 papers met the initial search criteria and among them, 92 papers were potentially retrievable including a description of 17 herbs and medicinal plants. In first step and by reviewing all published manuscripts on beneficial effects of herbs on serum lipids level, 17 herbs were described to be effective on lipid profile as lowering serum triglyceride, total cholesterol, low-density lipoprotein cholesterol as well as increasing serum high-density lipoprotein level. Some herbs such as celery could even affect the hepatic triglyceride concentrations. The herbal reaction toward different types of statins is varied so that grapefruit or pomegranate was interacted with only some types of statins, but not with all statin types. In this context, administration of herbal materials can lead to decreased absorption of statins or decreased the plasma concentration of these drugs. CONCLUSION Various types of herbs can potentially reduce serum lipid profile with the different pathways; however, the herb-drug interactions may decrease pharmacological therapeutic effects of anti-hyperlipidemic drugs that should be considered when approved herbs are prescribed

The evaluation of tubule formation in breast cancer using fraction of fields showing tubular differentiation (FTD) method and compare it with conventional methods

چکیده: زمینه و هدف: درجه بندی هیستولوژیک یکی از مهمترین عوامل پیش آگهی سرطان پستان است. تاکنون روشی برای تخمین کمی میزان تمایز غددی ذکر نشده است. لذا این مطالعه با هدف بررسی روش تجربی متعارف و مقایسه تکرارپذیری این روش با روشهای کمی (مورفومتریک در بزرگنمائی 200 میکروسکوپی) و نیمه کمی دیگر انجام گردید. روش بررسی: در این مطالعه توصیفی - تحلیلی، 38 نمونه هیستولوژیک سرطان مهاجم مجرایی پستان (موجود در بایگانی بیمارستان الزهرا (س) اصفهان) جهت ارزیابی میزان تمایز غددی، توسط دو مشاهده‌گر مستقل و به سه روش مختلف ارزیابی شدند. روش اول (متعارف): میزان تمایز غددی یعنی سطحی از تومور که تشکیلات غددی بدخیم ایجاد کرده، نسبت به کل نمونه به صورت درصد بیان شد. روش دوم، کسری از میدانها با تمایز غددی: در این روش میزان تمایز بصورت کسری از میدانها که حاوی تشکیلات غددی است نسبت به کل میدانها محاسبه می‌گردید و در روش سوم: در هر میدان میکروسکپی، بطور جداگانه، میزان تمایز غددی بصورت نیمه کمی تخمین زده شده و سپس میانگین میزان تمایز غددی در میدانها محاسبه شد. برای مقایسه اختلاف بین سه روش از آزمون فریدمن و برای مقایسه تکرارپذیری هر روش در بین دو مشاهده‌گر، از آزمون کاپا استفاده گردید. یافته ها: نتایج این مطالعه نشان داد که در روش دوم دو مشاهده گر بیشترین توافق را در نمره دهی نمونه ها داشتند به طوری که ضریب کاپا در روش اول 4/0، در روش دوم 832/0 و در روش سوم 558/0 بود (001/0