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Abstract Asphaltene deposition in surface facilities, wellbore and near wellbore region poses a chronic problem during oil production processes. It reduces permeability significantly by blocking pore throats as well as wettability alteration toward oil-wet. In this study, near wellbore damage due to asphaltene deposition is addressed. A numerical approach has been followed to investigate the impacts of asphaltene deposition in near wellbore region using an Iranian crude oil sample. An IMPEC (Implicit Pressure and Explicit Compositions) compositional simulator has been developed in cylindrical coordinates. Three mechanisms of asphaltene damage including porosity reduction, permeability reduction and wettability alteration are taken into account, and the impact of each mechanism is individually discerned. It is assumed precipitated asphaltene is a pure dense liquid and it is determined by LLE calculation using PR-EoS. The reduction in permeability is correlated with porosity reduction using a power law relation. To model wettability alteration, instantaneous wettability dependent properties (relative permeability, capillary pressure and residual saturations) are determined by a weight averaging between before/after deposition state. By assuming porous media is a bundle of capillary tubes, a weight factor is suggested which is sensitive to asphaltene particle size and their orientation on the surface and calculated dynamically during the simulation. Furthermore, sensitivity analysis is done to investigate the effect of model parameters. It is found that the wettability alteration is the main cause for the reduced production rate. Wettability alteration could reduce oil production even up to several times more than porosity and permeability reduction. The results also reveal that at early time of production, most deposition occurs in the vicinity of the well but as time elapses, the maximum deposition point expands gradually to farther areas from the wellbore. Highlights • An IMPEC compositional simulator in cylindrical coordinates is used to investigate asphaltene issue in near wellbore region. • Porosity reduction, permeability reduction and wettability alteration are taken into account. • The reduction in permeability is correlated with porosity reduction using a power law relation. • Wettability dependent properties are determined by a weight averaging between before/after deposition state. [ABSTRACT FROM AUTHOR]

The utilization of phase change materials (PCMs) in buildings leads to the reduction of energy consumption and maintaining the indoor temperature within the comfort range. The PCM performance strongly depends on the climatic conditions, causing a major challenge. To overcome this issue, the employment of a double-layer PCM system is introduced. The energy and economic assessments of various double PCM systems in the building located in different climatic conditions of Iran have been conducted for the first time. In this study, two PCM wallboards with different enthalpy and melting temperatures were embedded in the external walls of a residential building located in various climatic regions of Iran. The performance of the double-layer PCM system in five cities of Iran including Tehran, Isfahan, Shiraz, Tabriz, and Bandar Abbas during hot and cold months of the year was evaluated from energy and economic viewpoints. It was inferred that embedding a double-layer PCM system reduces the heating/cooling energy consumption compared to single-layer ones. It was concluded that the RT18/RT28 double PCM system was the best candidate to be employed in the external walls of the building located in Tehran and Shiraz, which reduced the total energy consumption of the building up to 6.26% and 5.17%. The RT18/RT22 double PCM system was the most efficient system for the building placed in Tabriz and Isfahan reducing the total energy consumption up to 4.41% and 3.87%, and the RT22/RT28 double PCM system had the best performance in the building located in Bandar Abbas, which could save 6.58% of total energy. Moreover, it was concluded that the use of a double PCM system reduced temperature fluctuations in the external walls. In addition, the economic analysis was performed using the dynamic payback period and the results revealed that the employment of a double-layer PCM system reduced the investment return period by up to 50%. [ABSTRACT FROM AUTHOR]

Background: Colorectal cancer (CRC) is the third most common cancer in Iran, where there is no organised CRC-screening programme. This study aimed to evaluate feasibility of CRC screening using a qualitative fecal immunochemical test (FIT) among Iranian average-risk adults. Methods: In this feasibility study, 7039 individuals aged 50--75 years were invited by community health workers (CHWs) in southern Tehran and its suburban districts between April 2018 and November 2019. The CHWs performed a qualitative FIT with cut-off level 50 ng Hb/mL buffer and referred those with positive-FIT for colonoscopy to the endoscopy center of Shariati hospital in Tehran. Outcomes included acceptance rate, FIT positivity rate, colonoscopy compliance, detection rates and positive predictive values (PPVs) with 95% confidence interval for CRC and advanced adenomas (AAs). Results: Acceptance rate at initial invitation was 71.7%. From 4974 average-risk adults (1600 males and 3374 females) who were offered FIT, 96.8% (n = 4813) provided valid samples, of whom 471 (9.8%) tested positive. Among FIT-positive participants, 150 (31.8%) underwent colonoscopy; CRC was detected in 2.0% (n = 3) and adenomas in 27.3% (n = 41). Detection rate of CRC and AAs per 1000-FIT-screened participants was 0.6 (0.1--1.8) [males: 0.7 (0.01--3.6), females: 0.6 (0.07--2.0)] and 4.2 (2.5--6.4) [males: 5.9 (2.6--11.0), females: 3.4 (1.7--6.0)], respectively. PPVs were 2.0% (0.4--5.7) for CRC and 13.3% (8.3--19.8) for AAs. There was no association between gender and the studied outcomes. Conclusion: Our results partially support the feasibility of scaling up organized CRC-screening through the existing healthcare system in Iran; it remains to be discussed carefully to ensure the capacity of healthcare system for adequate colonoscopy services. [ABSTRACT FROM AUTHOR]

Background: Colorectal cancer (CRC) is the third most common cancer in Iran, where there is no mass screening for the disease yet. We aimed to measure the feasibility of a pilot CRC screening program based on fecal immunochemical test (FIT) in Iranian population and the implications for scaling-up at the national level. Methods: A single quantitative FIT was offered by health navigators to individuals aged between 45 and 75 years in primary health centers in rural and urban areas in Tehran. Participants who had a positive FIT were referred for colonoscopy. Results: A total of 1044 asymptomatic average-risk individuals were enrolled. The mean age (SD) was 54.1 ± 7.0 years and nearly 63.0% (n = 657) were female. Only a small fraction of the participants had a prior screening practice (2.2%) and were aware of colon cancer (13.7%). In sum, 1002 returned the FIT kit, of whom the stool sample was unsatisfactory for testing in six participants (0.6%). The FIT uptake was 96.0%, positivity rate was 9.1% and the detection rates were 11.9% for adenomas and 7.1% for advanced adenomas. No cancer was detected. The positive predictive value (PPV) of the FIT was about 17% for any colonic neoplasms. Conclusion: This is the first study that reports minimal quality metrics within a CRC screening process. FIT modality as a test of choice for colon cancer screening in average-risk people is a safe and highly acceptable method of screening in Iranian people. The results of the current study may not be limited to Iranians, and could have implications to other developing countries with similar trends of CRC epidemic. [ABSTRACT FROM AUTHOR]

• Cultivar mixture can enhance bean competitiveness and by this decrease weed cover. • Cultivar mixture can allow highest yield with herbicide application at half rate. • Dose optimization with a cultivar mixture prevents herbicide over usage. • Cultivar mixture with reduced herbicide dose is a more ecofriendly weed management. Integrated weed control methods are increasingly demanded to maintain high yield while alleviating negative environmental side effects of control measures. Five field experiments were conducted during 2015–2017 at three locations in Iran to determine the advantage of exploiting enhanced competitive ability of bean (Phaseolus vulgaris L.) via cultivar mixture to reduce herbicide dose. For all experiments, the experimental design was split-plot in randomized complete block with four replications. Main plots were assigned to the factor "herbicide dose" with 5 levels between 0 and 100 % of recommended dose and subplots comprised monoculture of a stand growth type cultivar (STAND), monoculture of a climbing growth type cultivar (CLIMB) and the substitutive (50 % STAND/50 % CLIMB) cultivar mixture (MIXCR). Without herbicide application, the yield of STAND, CLIMB and MIXCR was estimated at 588, 1026, and 1637 kg ha−1, and the corresponding weed biomass (W 0) at 388, 215, and 239 g m-2, respectively. The herbicide dose to decrease W 0 by 50 % (ed 50) was estimated as 69 % of the recommended dose for STAND, while it was 53 and 45 % for CLIMB and MIXCR, respectively. Herbicide application at full rate increased the average yield of STAND by 2610 kg ha−1, but 1115 and 1532 kg ha-1 for CLIMB and MIXCR, respectively. Potential yield of CLIMB at full herbicide rate application was 2141 kg ha−1, while STAND and MIXCR showed statistically the same potential of producing 3198 and 3169 kg h−1 bean yield. However, MIXCR could achieve its potential yield at half of the recommended dose. Relative yield total (RYT) was lower than or equal to one at 75 % and 100 % of the recommended dose, but with decreasing herbicide dose to 50 or 25 % RYT raised to 1.2. Careful selection of cultivars for growing in mixture that combines strong competitor with high yield cultivars is crucial to achieve potential yield with less dependence on herbicides. As we could show for bean, this will help to overcome conflicting management objectives to reach both environmental and economic goals in weed control and crop production. [ABSTRACT FROM AUTHOR]