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It is more important to improve and complete the wastewater process in order to reuse and return it to the production line. In this study, the hydrogen peroxide/ozone process (Peroxone) was investigated as a supplementary step in paper mill wastewater treatment to reduce the amount of chemical oxygen demand and remove E. coli. In this regard, using the Box-Behnken Design method based on the response surface method to optimize and investigate the effect of three variables governing the ozonation process, including the amount of hydrogen peroxide consumed (ml), the amount of ozone input (mg/min) and ozonation time (min) were used. The results showed that the amount of ozone and hydrogen peroxide had the greatest effect for reducing COD (up to about 75%). Also, all three variables have played a significant role in increasing the efficiency of the Peroxone process and even completely eliminating E. coli. In determining the optimal conditions, the amount of ozone (146 mg/min), the amount of hydrogen peroxide (2ml) and the duration of ozonation (23 min), the lowest amount of residual COD (73 mg/L) and the highest efficiency (75% removal of E. coli) are predicted. The results showed that due to the interaction of ozone and hydrogen peroxide, the peroxone process performance was less efficient than the ozonation process alone.

In this paper, the thermo-electric, phonon, electronic, and optical properties of the C3N monolayer have been investigated using the Wien2K computational code based on first principles calculations in the framework of the density functional theory. The study of electronic properties shows the behavior of non-magnetic semiconductors with an indirect gap with a value of 0.5 electron volts for this two-dimensional structure. Also, optical properties such as dielectric function, reflection, energy loss function, absorption coefficient, and optical conductivity are calculated. C3N monolayer is optically anisotropic in z and x direction, which according to the refractive index diagram leads to birefringence, which is a key parameter for this compound's linear optical performance. The results provide a fundamental understanding of the design of composite structures used in nanodevices based on two-dimensional advanced materials. The linear response approach along the symmetric points calculates the phonon dispersion diagram. The results indicate the absence of negative modes in the phonon spectrum, indicating that the structure is dynamically stable. Investigating the thermoelectric properties of the C3N monolayer using the semi-classical Boltzmann theory shows that this monolayer has a value coefficient (ZT) close to one at room temperature and temperatures lower than room temperature. As a result, it can be proposed as a candidate for thermoelectric applications.

Many non-classicality indicators are used to measure the quantum effects of different systems. Kenfack's and Sadeghi's non-classicality indicators are introduced regarding the amount of Wigner distribution function's negativities and interferences in phase space quantum mechanics, respectively. Kenfack’s non-classicality indicator is used for cases just in the Wigner representation, whereas Sadeghi’s non-classicality indicator is effectively, applied for some real distribution functions. In this paper, we investigate these non-classicality indicators for the entangled photon number states in the Wigner, Husimi, and Rivier representations. It is shown that for a two-level entangled state, Sadeghi's indicator has more benefits to measure entanglement with respect to Kenfack's indicator. For the two-level entangled state, we also show a correspondence between Sadeghi's non-classicality indicator and the Von Neumann entropy. It is also shown that for the superposition of the squeezed number state and ground number state, the squeezing parameter affects the entanglement feature and Sadeghi's non-classicality indicator increases with the increase of the squeezing parameter.

Using the experimental results and data, the thermodynamic characteristics and thermal analysis of the electrical arc of torch electrodes and energy deposition in the waste-incinerator primary designed chamber were investigated. The temperature of arc in the intermediate electrode which is called the float nozzle was measured at 7000-8000 Kelvin based on the input power of 2 kW. The plasma plume temperature implied to be lower than the arc temperature according to the cold gas flow in the nozzle. The efficiency of energy transferring to the plasma plume is dependent on the geometrical electrode and nozzle design, and gas flow rate. After ten seconds, the chamber temperature was measured at 1193 Kelvin by thermocouple with the performance of electrical elements and plasma torch. The chamber temperature increasing in an adiabatic process was calculated at 1230 Kelvin after this time. According to the isothermal approach, the heat flow rate, and conduction loss calculation, the chamber temperature was obtained at about 900-1000 Kelvin. Using two approaches with inevitable approximations, the calculated temperature ranges for arc and plasma plume energy estimation have reasonable compatibility and this led to the road map of optimization and development for future torch planning and waste-incinerator chamber design.

In this work, considering the moment theory propagation of the laser beam with relativistic intensity in thermal quantum plasma is studied. Using the Maxwell equation and dielectric function obtained by the quantum hydrodynamic model, the mathematical equation for the laser beam width parameter is achieved and solved numerically by the fourth-order Runge-Kutta method. The results show that the stronger self-focusing effect is found in the moment theory compared to paraxial approximation. Also, similar to paraxial approximation, with growing Fermi temperature, plasma density and laser intensity, the oscillation frequency of the beam width parameter increases and focusing length decreases which means improving the self-focusing effect. Furthermore, it is seen that behaviors of the critical radius are not similar in the two theories, as in the moment theory, with increasing laser intensity, critical radius decreases until it becomes independent of the beam intensity, but in the paraxial approximation, the critical radius after a minimum value is enhanced with increasing laser intensity.

Gene expression is known as a phenomenon that shapes human life. This very complex phenomenon is formed from two stages: transcription and translation. In this study, we used the Nose-Hoover thermostat to model the effect of ambient temperature on gene expression since temperature regulates the biological clock of living systems. We have used the Lyapunov exponent approach to investigate the effect of control parameters on gene expression, including the degradation rates of messenger RNA and proteins, and to find critical points (phenomenon boundary limits), mRNA, and protein level boundary values. The rate of degradation in the process of protein synthesis has been investigated with the help of the Lyapunov exponent approach. According to this study, the optimal temperature for the production of mRNA molecules by Escherichia coli bacteria is 306 Kelvin. The study also used the chaos approach to show that the faster the mRNA molecules are degraded, the more they are transcribed, and the more chaotic the system becomes.

Entanglement plays a fundamental role in the field of quantum computing and quantum communication. In real conditions, a physical system is never isolated and inevitably interacts with its surroundings. Temperature is one of these effects that mainly reduces entanglement. In real conditions, the system is at a non-zero temperature, which will lead to a mixed state. Therefore, in the present work, the combined thermal entanglement of electron spin-oscillation in an anisotropic two-dimensional quantum dot is investigated using the negativity criterion. The results show that the combined entanglements are strongly dependent on the changes of the controllable parameters, such as the Rashba parameter and the magnetic field. The thermal entanglement between the spin and the assembly of oscillators is zero at absolute zero temperature and reaches a maximum with increasing temperature and then tends to zero asymptotically. This temperature, at which the amount of entanglement reaches its maximum value, can be controlled by changing the magnetic field and the coupling of the Rashba parameter. These two factors also control the rate of reaching the asymptotic state. These results provide a way to control the degree of entanglement between electron degrees of freedom, which is a fundamental requirement of quantum information processing.

In the last two decades, photonic crystals and structures that are based on them (photonic structures) have been examined and have been widely utilized in various optical applications. In this article, a theoretical and numerical model for the propagation of electromagnetic waves in multilayer dielectric structures is developed. The propagation of ultra-short light pulses in multilayer media and microresonators is investigated, and the energy reflection and transmission coefficients depending on the parameters of the environment and duration of the optical pulse are calculated. A method for calculating the transmission and reflection spectra of one-dimensional photonic crystal based on FDTD modeling with the emission of ultra-short optical pulses is proposed. To calculate the transmission and reflection spectrum of a one-dimensional photonic crystal and to simulate the propagation of ultra-short light pulses, in multilayer dielectric structures and microresonators, based on the numerical solution of Maxwell's equations with the finite difference approximation in the space-time domain, is performed.

In this study, The surface plasmon excitations in a dimer structure of closely spaced metallic nanospheres with different radii are investigated using the hydrodynamic model. Initially, an expression was derived to calculate this structure's multipolar surface plasmon excitations. Subsequently, the surface plasmon excitations in the dipole approximation were examined.The surface plasmon excitations in a dimer structure of closely spaced metallic nanospheres with different radii are examined using the hydrodynamic model in this study. It has been observed that the energy of in-phase modes is lower than that of out-of-phase modes in longitudinal or transverse excitations. Furthermore, at each separation distance between the nanospheres, the energy difference between in-phase and out-of-phase longitudinal modes is greater than that of transverse modes. The results show that with an increase in the separation distance between the nanospheres, the energies of in-phase modes increase, and the energies of out-of-phase modes decrease. At large separation distances, two plasmon modes are obtained, with the higher energy mode corresponding to the smaller nanosphere and the lower energy mode corresponding to the larger nanosphere. Finally, the local limit results are presented for comparison.

In this study, the optical and electronic properties of bulk and nano-layer of zinc selenide (ZnSe) and zinc sulfide (ZnS) are investigated. The calculations for solving the many-body Schrodinger equations are performed in the framework of density functional theory using the WIEN2K computational package. The Engel-Vosko and gradient generalized approximation (GGA) treat the exchange-correlation potential. To investigate the electronic and optical properties of zinc selenide and zinc sulfide nano layers, the electronic band structure and the real and imaginary parts of complex dielectric function for the bulk and nano-layer with different thicknesses are calculated and compared. The results of electronic band structures show that the energy band gap of zinc selenide and zinc sulfide nano-layers with various thicknesses decreases to zero and are metal. In contrast, the bulk of zinc selenide and zinc sulfide compounds are semiconductors. The results also show that for each compounds the static dielectric function for the perpendicular and parallel direction to the nano-layer surface is different from the bulk static dielectric function. Comparison between the real parts of complex dielectric function for the bulk and nano-layer shows that absorption of electromagnetic radiation for the ZnSe and ZnS nano-layer in comparison to corresponding bulk results occur in lower energies.

Background Research theses can have a significant impact on the development of applied sciences, especially when their results are published. Objective This study aims to determine publication rate of papers extracted from the medical residency and master’s degree theses of Guilan University of Medical Sciences (GUMS) during 2008-2018. Methods This is a descriptive cross-sectional study. The data were collected from the medical residency and master’s degree theses of GUMS from 2008 to 2018. Then, they were searched in international and national databases according to the title, keywords, and names of supervisors, advisors, and students. Results Of 774 theses, 449 (58 %) papers had been extracted and published in journals indexed by ISI/ PubMed (41.2%), Scopus (11.8%), BIOSIS, Chemical Abstract, and Embase (0.44%) and others (46.56%). Most of them (98.66%) were original research. Moreover, in 383(85.3%) of the theses, there was no statistician or data advisor. The median time from defending theses to the publication of a paper from them was two years. Conclusion The publication of papers extracted from the theses of GUMS has increased, and more than 50% of them have been published in journals indexed by ISI, PubMed, and Scopus. However, the factors associated with the publication of papers need to be surveyed. [ABSTRACT FROM AUTHOR]

Background and aim: Nowadays, increase in population have caused increasing demand for paper, and in addition, greater restrictions on raw materials, initiated the production of high-yield pulps and mechanical pulps has found special status. These pulps are produced with the yield greater than 85%. The utilization of these pulps due to the presence of lignin, extractives, and metal ions, is limited to short-term usage, as in the long they suffer from brightness reversion and photo-yellowing. This study aimed to investigate the effect of DTPA, nano-cellulose, and nanochitosan spray on the optical properties of chemical-mechanical pulp (CMP). Materials and methods: For this purpose, first, a quantity of bleached chemical-mechanical pulp (CMP) was selected as a control sample from Mazandaran wood and paper industry. Papers with a basis weight of 60 gr/m² were prepared from the mentioned paper pulp. In this study, the nano-fibrillated cellulose (NFC) was purchased from Nano Novin Polymer Co. (Sari, Iran), which was prepared from softwood alpha cellulose pulp with an average fiber diameter of 32 nm. The NFC was sprayed at 2% on paper sheets. Nanochitosan (“Seafresh”, Thailand), with a deacetylation degree of 93% and a molecular weight of 270 kDa was used. Nanochitosan was sprayed at 1 and 2% of the dry pulp weight. Diethylene triamine penta acetic acid (DTPA) was prepared from DIPER-Samchun (South Korea(. To spray the DTPA onto the paper surface, 0.5% DTPA solution was prepared. To prepare samples for the surface modification, paper sheets with a basis weight of 60 g/m² were made. Then, 0.5% DTPA, 2% nanochitosan, and 2% nanocellulose were sprayed separately on the paper sheets. In addition, another treatment named mixed-solution (containing 0.5 % DTPA + 2% nanochitosan + 2% nanocellulose) was sprayed on the handsheets. The spraying time and distance were 20 s and 20 cm, respectively, and the treatment process was named “spray-coated”. Then, the optical properties (brightness, opacity, yellowness, and greenness) of the hand-sheets were measured according to ASTM and TAPPI standard methods. Results: The results showed that by DTPA, nano-cellulose, and nano-chitosan spray on the handsheet paper, brightness, yellowness, greenness, L* factor, and the opacity increased and the a* factor decreased. By spraying nano-cellulose on the test samples, most of the optical properties were significantly improved except for the yellowness of the handsheet paper. In addition, the most appropriate properties were observed in the paper obtained from DTPA spray and also in the simultaneous spray treatment of DTPA, nano-cellulose, and nano-chitosan on hand-sheet papers. Therefore, it has caused a very sensible increase and improvement in all the optical properties, which can be selected and suggested as the best treatment. The evaluation results of the brightness reversion of the hand-sheet paper from CMP pulp showed that most of the treatments led to a relative reduction of the return of the paper brightness. On the other hand, the lowest and highest brightness return values in the hand-sheet paper were obtained from 0.5% DTPA spray and nano-chitosan spray, respectively. The evaluation results of the SEM images of the test samples compared to the control sample showed that the hand-sheet paper with nanochitosan and nano-cellulose spray and also in the simultaneous spray treatment of DTPA, nanocellulose, and nano-chitosan had more favorable surface and structural properties. The existence of less empty spaces (cavity) and more overlap of fibers in the test samples can be a reason for the higher quality of the properties, as well. Conclusion: The results showed that by spraying nanocellulose, nano- chitosan and DTPA on the test samples, the optical properties, brightness, greenness, opacity, a* factor, l* factor, yellowness and brightness stability improved. In addition, among the various treatments, the DTPA treatment in long-term thermal aging and the use of chitosan-nano and nano-cellulose in the short-term aging had noticeable effects on brightness stability and decrease in the color reversion. As a result, there was an increase in the durability of the paper against thermal deterioration. [ABSTRACT FROM AUTHOR]

Background and objectives: Some medicinal herb extracts have the antibacterial capability. On the other hand, herb extract is one of the organic, natural, and environmentally friendly substances. In recent years, the production of environmental and safe packaging materials has attracted the attention of scientists and industrialists. Paper is one of the biodegradables and lowcost options for packaging in various industries, including the food industry. Also, the raw materials of paper can be modified and changed with different materials. As a result, paper fibers can be treated with herb extracts and used in the production of renewable papers with antibacterial properties. Methodology: In this research, thyme plant residue (Zataria Multiflora) was used for extraction. The thyme obtained from the research farm was dried and then powdered. 10 grams of thyme powder was poured on 100 ml of ethanol and then it was treated with an ultrasonic probe. In this method, two amplitudes of 40 and 60 amplitudes and three time levels of 3, 6, and 9 minutes were used for extraction. Then the papers with 120 grammage were treated with herbal extract prepared using two dosages of 15 and 20% based on the dry weight of the paper by spraying. The antibacterial properties of the papers were investigated with Escherichia coli and Staphylococcus aureus bacteria. The chemical structure of the extract from the thyme was investigated by Fourier transform infrared spectrum (FTIR) analysis. Also, gas chromatography (GC-MASS) analysis was used to investigate the components of thyme extract. The optical properties of the paper, including brightness and opacity, and the strengths properties of the produced papers were measured by tensile, tear, and burst strengths. Results: The highest inhibition zone diameter in the treated paper with the thyme extracted by ultrasonic method was 20 mm in 40 amplitude and 9 minutes for Escherichia coli bacteria. Also, the highest inhibition zone diameter for Staphylococcus aureus bacteria was 14 mm in 60 amplitude and 6 minutes. According to the results of the papers analysis, the papers showed better antibacterial properties and higher inhibition zone against the Escherichia coli bacteria. The chemical compounds in the thyme extract including various substances such as hexane and furans. The most important chemical components that caused the antibacterial properties of the papers is carvenone, which was observed in the thyme extract. The results of the strength test of the treated papers showed that the sample of the thyme extracted by the ultrasonic method at 40 amplitudes, 3 minutes, and the 20% consumption amount based on the dry weight of the paper has the highest tensile and burst index. As well as, the highest tear index of the treated papers was in the treated sample with the thyme extracted at 60 amplitudes, 3 minutes, and 15% consumption amount based on the dry weight of the paper. The results of the optical tests showed that the opacity of the papers decreased and the brightness increased. Conclusion: The results of this research showed that the paper as a biodegradable and environmentally friendly material has the ability to be treated with herbal and natural antibacterial materials such as the thyme extract. Also, the herbal extracts are a suitable alternative to inorganic and metallic materials in the production of materials with antibacterial properties due to the herbal extracts are cheap, available and natural materials. [ABSTRACT FROM AUTHOR]

Randomized factorial design was implemented in four replications to determine optimal methods of Ajwain (Carum capticum) standard seeds germination in SPCRI. Ajwain seeds were placed top and between paper and sand exposed to two potassium nitrate (two grams per 1000 ml distilled water) and pre-chilling (seven days under 7-10ºC) pre-treatments which were under six temperatures (10, 15, 20, 25, 20-30, and 35ºC) in germinator for 25 days so as to germination indices were assessed. Ajwain seeds viability was estimated 75% after tetrazolium test. The highest final and normal seedling percentages were found under 15 and 20ºC in pre-chilling treatment and also 20ºC in potassium nitrate and control. No germination was observed under 35ºC in potassium nitrate and control, however, pre-chilling led to >26% germination. The higher germination potential was shown in top and between papers compared with sand. The lowest germination rate was recorded in control and potassium nitrate and the highest one in pre-chilling. The maximum of seedling weight vigor was suggested in top and between paper when seeds were put under 10, 15, and 20ºC. In order to evaluate optimal standard germination of Ajwain seeds, it was resulted that applying of two potassium nitrate and pre-chilling treatments placed top and between papers under 15 and 20ºC caused maximum of germination potential and seedling weight vigor. [ABSTRACT FROM AUTHOR]

The division of domestic labor at home has historically evolved since industrialization and has been important as a social phenomenon in academic discussions since the 1970s. Social and economic contexts have always influenced the relationships and interactions between men and women and their gender roles in the family. This paper describes the women's experience of domestic labor division with their husbands in the family. In addition, analytical concepts such as gender equality in the division of domestic labor, economic dependency, and gender deviation neutralization (in gender roles) under the theory of relative resources have been used. Also, the thematic analysis method and semi-structured interviews with 15 women in the age groups of 20 to 60 years, were used in this paper. Most female respondents were 40 to 50 years old (47%), and most of them, equivalent to 40%, had a bachelor's degree. Women were selected from different occupational situations including: homemakers, teachers, hairdressers, tailors, employees, university professors, and domestic workers. Also, 80% of the interviews were conducted with working women and 20% with homemakers. Then, interviews were analyzed using Max QDA 2018 software to extract the relationship patterns of couples in the division of domestic labor. The findings indicate the extraction of 2 main themes, seven sub-themes(including: Stubborn femininity, Hegemonic masculinity, Self-sufficiency, Persuasion, the gradual participation of men and Equality in relations) and 228 concepts. [ABSTRACT FROM AUTHOR]

Al-Askari Shrine is one of the four Shiite shrines in Iraq. Throughout past centuries, Iranians played a key role in the development and conservation of this shrine. In recent decades, this shrine has undergone alterations, both physically and spiritually, with its historical and religious values, especially those of pilgrimage rituals having shrunk. The recognition of the genuine, authentic status of this shrine is a vital prerequisite in preparinga conservation plan. The present paper asks how the structure and parts of the shrine were before its substantial repairs in the early Qajar period. Among pieces of historical evidence, an illustrated pilgrimage scroll called the Niebuhr scroll is essential in recognising the shrine's building status before the 18th century. In the present paper, the paintings of the shrine will be interpreted based on the visual language of this scroll. The interpretation also uses some written pieces of historical evidence. The paper proposes that before the 18th century the Al-Askari shrine had two separate parts: first, the mausoleum of the two Imams Ali al-Hadi and Hassan al-Askari (the Mashhad), and second a shrine above the holy Cellar, from where Imam Mahdi's occultation is believed to have occurred (the Maqam). These two parts were adjacent but segregated. The Mashhad had a chamber with a dome on a high drum, and an arcade around, probably without any minaret and courtyard. The Maqam seemingly was a freestanding monument with a muqarnas dome, and without any courtyards. Unlike today, the access way of the Cellar was through a staircase inside the Maqam and its pilgrimage ritual was fitted with this access way. [ABSTRACT FROM AUTHOR]

Background and Objective: Bacterial nanocellulose is known as a potential carrier for a widespread spectrum of biological compounds, including antibacterial and antifungal compounds. The present study was conducted to determine the impact of bacterial nanocellulose containing Natamycin and Amphotericin B on Aspergillus flavus and Penicillium citrinum in an in vitro environment. Methods: In this descriptive-analytical research, Aspergillus flavus-PTCC: 5006 and Penicillium citrinum-PTCC: 5304 fungi were prepared from the Fungal Collection of the Department of Microbiology, Faculty of Veterinary Medicine, Urmia University. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of Natamycin and Amphotericin B against Aspergillus flavus and Penicillium citrinum were evaluated by the microdilution method. Bacterial nanocellulose was prepared using Komagata xylinum bacterium, and Natamycin and Amphotericin B were added in three concentrations of 0.01%, 0.05%, and 0.1% to wet and lyophilized nanocellulose films by the immersion method. Then, the antifungal effects of the film containing the above compounds against the investigated fungi were investigated by the agar diffusion method. Parchment paper was used as a control for comparison. Spectral properties of nanocellulose film containing antifungal compounds were evaluated by the Fourier transform infrared (FTIR) method. Results: MIC and MFC of Natamycin for Aspergillus flavus were determined as 3.9 μg/mL and 7.81 μg/mL, and for Penicillium citrinum as 7.81 μg/mL and 15.62 μg/mL, respectively. MIC and MFC of Amphotericin B for Aspergillus flavus were determined as 7.81 μg/mL and 15.62 μg/mL, and for Penicillium citrinum as 15.62 μg/mL and 31.25 μg/mL, respectively. The increased concentration had a statistically significant impact on the antifungal properties of all films (P<0.05). The best antifungal effects of the film were related to the film containing Natamycin. Conclusion: Bacterial nanocellulose containing Natamycin showed stronger antifungal effects in an in vitro environment compared to Amphotericin B against Aspergillus flavus and Penicillium citrinum. [ABSTRACT FROM AUTHOR]

The process of sense perception has been a subject of discussion in Islamic philosophy, and four theories have been proposed to explain the sense perception process. Before Sheikh Ishraq, mystics focused on impressions in sense perceptions, and mathematicians considered the emergence of rays in visual perception. Suhrawardī, through criticizing the theories before him regarding visual perception, emphasizes the relation of illuminational relation (al-iḍāfa al-ishrāqiyya) and the direct connection of the human soul with external agents. Although he extensively discusses the quality of visual perception, he has not explicitly addressed the quality of perception in other sense faculties. This has led some to doubt the generalization of his theory to other sense perceptions. In this paper, we attempt to provide evidence for the generalization of Suhrawardī's theory to other sense faculties. To demonstrate the effectiveness of this theory in his philosophical system, we study some of its functions within his philosophical system. In this article, we present three pieces of evidence for the generalization of his theory to other sense faculties, and among these three pieces of evidence, two are considered innovations in this paper. Finally, we will examine the functions of this theory in Suhrawardī's theological-philosophical system. [ABSTRACT FROM AUTHOR]

The water productivity index (WP), which is defined as the crop produced per unit of consumed water, has been considered as a key indicator for the optimal use of water in the agricultural sector. It has been heavily relied upon in the Iran's agricultural water policies and plans. However despite several years have passed since the introduction of this concept and index, unfortunately, water crisis still exists and is expanding in the country and measures to increase WP in agricultural products have not yet been able to effectively solve the country's water issues. In this review-analytical paper, the issues and challenges of using this index in practice have been discussed and the shortcomings, challenges, measures, and infrastructure necessary for the proper use of this index have been discussed and analyzed. According to the results, there are hidden issues and challenges (in 8 groups) in its application. The most important of which are the need to deeply understand the concept and definition of WP in the country's expert and management community, and the problems and issues of using the index from the aspect of lack of the required infrastructure for the proper impacts of improving WP in mitigating water scarcity. According to the identified issues and challenges, it was concluded that improving WP could not be a sole measure to solve the country's water crisis, because it fulfills just initial conditions. In order to fulfill conditions sufficiently and to implement related comprehensive measures and interventions, the necessary hardware, software, legal, and policy infrastructures must be provided. Introduction The water productivity index (WP), which is defined as the crop produced per unit of consumed water, was launched in the world with the aim of reducing water consumption and allocating more water to the environment. In compliance with that, this theoretical concept and index has presented itself in the literature and even in the macro-level laws and documents and development plans of Iran. Therefore, it has been considered as a key measure and indicator in the optimal use of water in the agricultural sector, and has been heavily relied upon in the Iran's agricultural water policies and plans. However despite several years have passed since the introduction of this concept and index, unfortunately, water crisis still exists and is expanding in the country and measures to increase WP in agriculture have not yet been able to effectively solve the country's water scarcity issues. There are various issues and challenge in use of concepts and indicators explaining the optimal and efficient use of water in practice, and they should not be relied on without the necessary studies and evaluations. Therefore, the objective of this review-analytical paper is to investigate and analyze the hidden issues and challenges of the WP index in its practical use with the aim of managing and mitigating agricultural water crisis in Iran. Materials and Methods The research method is mainly based on collecting and reviewing international and national scientific literature related to the subject, use of the national results and statistics, macro-level national laws and documents, experiences and opinions of the experts, together with the required analysis and discussions. This review-analytical paper deals with the problems and challenges of using the WP index in practice. Therefore shortcomings, challenges, arrangements, and necessary infrastructure for the optimal use of this concept and index have been discussed and analyzed. Results and Discussion According to the results, the WP index has hidden problems and challenges in its application in practice. These include: 1) The need to properly understand the concept and definition of WP in the water and agriculture experts and management community of the country, 2)The problems and issues of using the index from the aspect of lack of the required infrastructure for the proper impacts of improving WP in mitigating water scarcity, 3) Real and correct understanding of the concept from the aspects of the existence of internal relationship between the numerator and the denominator of the index and the correct selection of relevant solutions for the effectiveness of the activities and interventions, 4) Weaknesses in in index in regard to defining WP in conditions out of human management in the production of agricultural products, 5) Issues and challenges related to comparing the results of WP values in different biophysical, geographical, and management conditions, 6) The challenge of choosing productivity approaches. i.e. physical or economic WP and choosing the optimal national index for water management and choosing the appropriate cropping pattern, 7) The challenge of choosing a management scale and the issues of determining WP at the basin scale, and 8) The existence of flaws and shortcomings in the WP index itself in terms of its comprehensiveness to apply it as an index. Conclusion In response to the question whether improving WP can be a fundamental solution to solve the Iran's water scarcity and save the country from this crisis, it must be acknowledged that the answer depends on the difficult choices that policymakers have to make regarding water resources, as well as the provision of necessary hardware, software, legal and policy infrastructures for the related comprehensive solutions and interventions which includes: volume delivery of water, water accounting, preventing the expansion of cultivated area, preventing the changing of the copping pattern to water-intensive crops, updating laws and creating the necessary executive guarantees for the implementation of approved laws, comprehensiveness and having a regional and national perspective, taking into account the participation of the stakeholders, and providing the necessary financial resources. Accomplishing these criteria is very complicated due to the diverse goals and interests of different actors and the various scales and systems in which the use of agricultural water is placed, and doing all of them may not be practical in the short term. Considering the hidden issues and challenges mentioned, improving WP could not be a sole measure to solve the country's water crisis, because it fulfills just initial conditions. In order to fulfill conditions sufficiently and to implement related comprehensive measures and interventions, the necessary hardware, software, legal, and policy infrastructures also must be provided. [ABSTRACT FROM AUTHOR]

Periphyton is a complex biological community comprising microorganisms and organisms from different physiological groups that collectively attach to various submerged surfaces in wetland ecosystems. Periphytic biofilms play a critical role in the wetland ecosystem’s dynamicity and possess a considerable capacity for decontamination. The following article examines the various aspects of periphytic biofilms’ capacity for removing some of the most critical environmental pollutants, including organic pollutants, pharmaceuticals, heavy metals, microplastics, and excess nutrients. The paper provides comprehensive discussions on the critical pollutant removal mechanisms employed by the periphytic communities. Additionally, the paper endeavors to contribute to the available knowledge regarding utilizing and developing periphyton-derived bioremediation technologies by presenting the most recent research findings, discussing common challenges in periphyton’s biotechnological application, and delineating crucial research gaps to postulate future research questions. Applying periphyton in pollutant removal aligns with the most recent paradigm of bioremediation technologies advocating the use of microbial consortia instead of single microbial species. In this regard, research results convey that the simultaneous presence of multiple microbial groups together in a biological community (such as periphyton) increases the microorganisms’ resistance to unfavorable environmental conditions and enhances the biological community’s capacity for decontamination. Based on the studies presented in this article, periphytic biological communities can employ different mechanisms to transform and biodegrade a wide array of pollutants. [ABSTRACT FROM AUTHOR]