z. akbari

Photon-photon coincidence counting is a primary standardization technique used for the absolute activity measurement of short half-life radionuclides. In this study, a coincidence spectrometer based on digital signal processing was developed for the absolute standardization of 125I seed Brachytherapy. The spectrometer includes a waveform digitizer that samples at the preamplifier signals directly from two similar 2ʺ × 2ʺ NaI (Tl) detectors. The sampled signals were shaped into trapezoidal signals for pulse height analysis. These detected signals were then recorded in a list file and the software was used to recognize coincidence events. Detailed discussions were included on the formulas for determining absolute activity measurement. The activity of a 125I seed was measured and showed good agreement with the reference values. This presented technique is a quick method for measuring the activity of 125I at nuclear hospitals. The standardized source can also serve as a tracer for measuring the activity of the 109Cd source

One of the most effective ways to preserve biodiversity is to convert conventional systems into organic ones. The organic farming system reduces the negative effects of intensive management. The biomass of the soil ecosystem has different responses in management methods including tillage, fertilizer and defense inputs, and organic modifiers. Understanding the role and responses of biomass in different cropping systems is essential to support sustainable horticultural practices in managing plant-parasitic nematode.

Sampling has been done from two organic farming systems, conventional and pasture, in order to identify the morphology of soil plant parasitic nematodes, soil physicochemical characteristics, and microbial respiration. Plant parasitic nematodes were extracted, killed, fixed, and transferred to glycerin and permanent slides were prepared. The effect of the type of cultivation system on the abundance and diversity of plant parasitic nematodes in common and organic apple and peach orchards compared to pasture were investigated by multivariate analysis of variance (MANOVA) in Xlastat 2020 software.

20 Genera belonging to 11 families of plant-parasitic nematodes were identified, which had different frequencies based on the type of cropping systems and crops. The comparison of the type of organic cultivation system with the common showed that it had a significant effect on the frequency and diversity of plant parasitic nematodes; the highest frequency of the nematode genus in organic peach cultivation system is Gracilacus and the lowest frequency is Scutylenchus genus in common apple cultivation. The abundance of nematode family in organic system is more than common and the abundance of nematode family in peach organic system is more than apple organic system. It should be mentioned that the common apple system is close to pasture in terms of abundance. The abundance of nematode family in the common system of peach is more than the common system of apple. The type of cultivation system had a significant effect on the frequency and diversity of Pratylenchus, Helicotylenchus, Tylenchus, and Rotylenchus genera, while it did not have a significant effect on the  Gracilacus genus. Type of host plant had a significant effect on the frequency and diversity of plant parasitic nematodes definitely in all soil condition variables. The type of host plant was significant on the frequency of all plant nematodes except Tylenchus and a significant effect on the diversity of all except Tylenchus and Rotylenchus. Among all soil factors, microbial respiration, EC, OC, K, P, and texture (percentage of soil particles including sand, silt, and clay) showed a significant effect on all lineages of nematodes.

Significant differences in community structure in plant parasitic nematode communities in three systems were recorded. The results of the present study have shown that the frequency and diversity nematodes are different from the results of other researchers in apple and peach orchards, that plant types and cultivars, basic genotype, or soil management practices affect the composition of plant parasitic nematode community groups. In this study, the abundance and diversity of nematode in the organic system was more than in pasture, and conventional agriculture with more than 10 years of history, including tillage and chemical inputs, and organic matter loss, erosion, and low in the soil agroecosystem. The reduction of the plant parasitic nematode in the conventional system compared to the organic system is caused by the reduction of organic matter, tillage, or chemical inputs. The results showed that the type of product and management practices affect nematode communities. The composition of soil nematode communities is significantly different in organic, conventional, and pasture farming systems. The organic peach and apple system is facing an increase in nematodes more than conventional. It seems that plant parasitic nematodes are sensitive to soil management practices. Soil nematodes are useful indicators to evaluate the intensity of management and sustainable management of horticultural ecosystems on soil ecosystem performance; because they have several feeding habits in soil, and micronutrient networks and play an important role in the food cycle, pest suppression, and regulation of microbial communities. There were high pest pressure of nematodes in the organic peach farming system in comparison to the apple farming system. In this research, apple is better than the peach for organic production in Damavand orchards. In addition, growers consider peaches better than apples due to market and price considerations. With the increase in the demand and price of organic products, the organic system is facing high pest pressure due to fewer management options compared to the conventional system, which requires the development of integrated plant nematode management strategies.

This study aimed to investigate the distribution of natural and anthropogenic pollutants and the enrichment of elements in air dust of Khuzestan province following the dust events. Dust samples were collected from nine regions including, Abadan, Ahvaz, Hoveyzeh, Susangerd, Shush, Omidieh, Ramhormoz, and Mahshahr. The INAA technique measured the concentration of elements. Using the results of PMF modeling and investigation of obtained factors for samples, a suitable reference element with the most negligible influence from pollutant sources was selected and used for EF calculations.  The results showed very large enrichments with EF> 20 for elements such as Zn, Se, Br in Susangerd, Ahvaz, and Abadan. The concentrations of Fe, Al, and Mg in some areas of the province were much higher than LC50. The enrichment factors and the correlations between the elements in the samples of various regions showed their dependence on local pollutant sources.

Small changes in pressure or temperature, close to the critical point, lead to large changes in solubility of supercritical carbon dioxide (CO2). Environmentally friendly supercritical CO2 is the most popular and inexpensive solvent which has been used for preparation of nanodrugs and nanocarriers in drug delivery system with supercritical fluid technology. Delivery of a drug is one of the most challenging research areas in pharmaceutical sciences. With a combination of drugs and innovative delivery systems such as lipid nanocarriers, drugs efficiency and safety have been improved significantly. There are various techniques available to produce drug loaded solid lipid nanoparticles. Among them, supercritical fluid technology has been identified as potentially effective and applicable approach which has attracted increasing attention during recent years. This technique has several advantages such as avoid the use of solvents, particles are obtained as a dry powder, instead of suspensions, mild pressure and temperature conditions can be applied. Nevertheless, little attention has been paid to formation of drug loaded solid lipid nanoparticles by supercritical fluid technology. In this paper, we present a brief introduction to solid lipid nanocarriers. Then a general overview of different processes of supercritical fluid technology has been provided and also case studies are presented to show the potential benefits of this approach in drug loaded solid lipid nanoparticle production.