Harmful Contamination Research Articles

Determinants and Evaluation of Onsite Water Loss Due to Leakages in a Selected Institution in South Africa

Water loss due to onsite leakage is a problem in the effective management of potable water mostly in semi-arid and arid countries of the world whose quantity of freshwater is depleted, and recharge is highly variable. This study assessed the quality and quantity of water loss in an academic institution due to onsite leakage resulting from various drivers such as leaks, corrosion, pressure, ageing infrastructure, and student attitude. An observational approach was used for water loss analysis. Samples were collected from each point from which water is lost and analyzed for physicochemical parameters, indicator microbes, and trace metals using standard procedures. It was observed that a high amount of water is lost in the study area which was partly influenced by high water pressure, the corrosion of taps and faucets, tap faults, and leaks. A total water loss of 9013.56 L/day in three selected residences of the institution was recorded. The wasted water was found to be of good quality with no harmful contamination. The Metal Pollution Index (MPI) showed that the water poses no threat from trace metals with a maximum MPI value of 7.76. The sampled water quality complied to the South African National Standard and World Health Organization standards for drinking water. The hazard quotient and hazard index both showed a level less than one, implying no possible non-carcinogenic risk associated with the consumption of the water. The wasted water from the institution’s residences is therefore of a very high quality and needs to be conserved for better usage.

Concept for a Portable Measuring Device for the Quantitative Detection of Legionella

According to the drinking water regulation, drinking water systems must be tested for harmful contamination at specified intervals. To meet the legal requirements and save costs and time, a portable analysis method is to be developed. For this purpose, a concept study was conducted. It describes a portable measuring device for the quantitative detection of legionella using real-time PCR. The study includes the construction elements and conditions that are necessary for the collection, processing, and evaluation of the sample. It was found that commercially available PCR systems do not meet the size requirements and can only be represented by an in-house development. In addition, a microfluidic system must be developed that is designed for one-time use and low production cost.

PECVD barrier coating systems on post-consumer recyclates for food contact applications

ABSTRACT As using recyclates in the food sector is currently severely restricted due to the risk of harmful contamination, the reuse of PCR (Post-Consumer Recyclates) could be greatly increased through the development of migration barriers. However, the deposition of functional barrier coatings in PECVD processes (Plasma-Enhanced Chemical Vapour Deposition) on thermoformed PCR polypropylene cups is non-trivial due to complex geometries and difficult surface properties (high roughness, non-polarity, fluctuation of recycylate properties). To develop barriers in this system, material properties of recyclate and virgin material were compared by rheometric and thermal analysis and surface properties of PCR and virgin material cups were analysed morphologically in order to define specific coating challenges. Subsequently, coatings were deposited by PECVD consisting of both, silicon organic intermediate layers (SiOCH) and silicon oxide barrier layers (SiOx). The barrier, measured by the oxygen transmission rate, could be improved by a factor of about 60 compared to uncoated cups.

Highly effective reduction of phosphate and harmful bacterial community in shrimp wastewater using short-term biological treatment with immobilized engineering microalgae

Shrimp farming wastewater includes high amounts of phosphate and microbiological contaminants, necessitating further treatment before release into receiving water bodies. After 24 h of shrimp wastewater treatment, alginate beads containing the blue-green algal Synechocystis strain lacking the phosphate regulator gene (mutant strain ΔSphU) at 150 mg L−1 reduced phosphate content from 17.5 mg L−1 to 5.0 mg L−1, representing 71.5% removal efficiency, with phosphate removal rate reaching 6.9 mg gDW−1 h−1 during photobioreactor operation. For short-term treatment, removal rates of nitrate, ammonium and nitrite were 42.7, 48.5 and 92.9%, respectively. Microalgal encapsulated beads also impacted the bacterial community composition dynamics in shrimp wastewater. Next-generation sequencing targeting the V3–V4 region of the 16S rDNA gene showed significant differences in bacterial community composition after 24 h of treatment. Proteobacteria are the most abundant phylum in shrimp wastewater. After 24 h of bioremediation, reductions of harmful bacteria in the Cellvibrionaceae and Pseudomonadaceae families were recorded at 5.85 and 3.18%, respectively. Engineered microalgal immobilization under optimal conditions can be applied as an alternative short-term bioremediation strategy to remove phosphate and other harmful microbial contamination from shrimp farming wastewater.

Comparative Analysis of Aerobic Composting of Fresh Cut Floral Waste

Abstract Increased levels of pesticide applications are used when growing cut flowers in many developing countries where most are grown and where they are less restrictive on pesticide use when compared to regulations in the United States. Therefore, special consideration should be given to cut flower disposal from floral shops that utilize flowers from other countries due to the potential for pesticide leaching into land and waterways. Most retail florists in the industry dispose of their floral waste in municipal dumpsters. While the United States Department of Agriculture (USDA) has stringent guidelines to prevent the importation of insect and disease pests, there are no regulations regarding residual pesticides or other harmful chemical contamination on imported floral crops. Composting is one technique used as an alternative waste management method to traditional landfill dumping and can produce a valuable commodity for agricultural, horticultural, and related industries. The main objectives of this study were to compare the physicochemical properties of two different compost protocols that incorporated cut flower and foliage waste and to determine whether pesticide residues remained in the finished compost. Analysis of results were based on the U.S. Composting Council's Tests Methods for the Examination of Composting and Compost used by the U.S. Composting Council's Seal of Testing Approval (STA) program. When compared to STA standards, both compost samples pH, total nitrogen, C:N ratio, and bioassay were found to be within normal ranges for compost sold in the horticulture industry. Chemical analysis found the levels of arsenic, cadmium, copper, lead, mercury, molybdenum, nickel, selenium, zinc all to be well below set industry standards. Additionally, the compost was tested for 23 herbicides and insecticides. Of those, two herbicides (clopyralid and MCPA) and one insecticide (lufenuron) were found in the sample in trace amounts, though well below USDA standards for food crops after the composting process. Results indicated floral waste collected from retail flower shops has the potential to be incorporated into a composting system to create a quality compost suitable for use in the horticulture industry.

Trace heavy metals and harmful elements in roots and rhizomes of herbs: Screening level analysis and health risk assessment

ObjectiveHeavy metal and harmful element contamination are frequently reported in Chinese herbal medicines (CHMs), and roots and rhizomes parts showed a higher content than other parts. To investigate the residue level and assess the potential human health risk of heavy metals and harmful elements in roots and rhizomes, 720 batches of the sample representing 20 species of herbs from different sources were collected. MethodsThe content of Pb, Cd, As, Hg, and Cu in the digests was determined using ICP-MS. The chronic hazard index estimate based on non-cancer hazard quotient (HQ) was applied for potential health risk assessment of Pb, Cd, As, Hg, and Cu via consumption of CHMs. ResultsCompared with the Chinese limit standard (Chinese Pharmacopoeia Commission, 2020 edition) of Pb, Cd, As, Hg, and Cu in Ginseng Radix et Rhizoma, the exceedance percentage of Pb in total samples was 14.1%, which were generally far higher than Cd, As, Hg, and Cu. Health risk assessment results based on hazard quotient calculating showed that total HQ of Cu, Pb, As, Cd, and Hg in Pulsatillae Radix and Clematidis Radix et Rhizoma exceeded 1, with the value of 1.543 and 1.235. Besides, Arsenic had the highest HQ value (0.957) in Pulsatillae Radix. ConclusionConsuming raw materials of Pulsatillae Radix and Clematidis Radix et Rhizoma may pose a potential risk and Arsenic residues in Pulsatillae Radix deserved special attention.

THE PROSPECT OF INTERPLANETARY MISSION: ARE WE READY?

Mars exploration missions in the future will be focused on Mars Sample Return (MSR) and humans as space crew in late 2028 or early 2030 by NASA and other non-government entities, such as Space Exploration Technologies (Space X) and Blue Origin. MSR and sending humans to explore Mars raises environmental contamination issues, which are governed in law by Article IX of the Outer Space Treaty 1968 to “avoid harmful contamination.” Though there is no existing international law instrument to address this issue comprehensively, Article IX was not clear to explain harmful contamination. Thus, non-governmental entities involved in future missions to Mars face liability, especially in the case of an accident causing fatalities or adverse environmental impact for the Earth and Mars. This article examines related regulations in corpus iuris spatialis, including soft law and elaborating with astrobiological data to encourage new regulation, ensuring liability and environmental safety on future Mars missions.

On-site production of high-purity hydrogen from raw biogas with fixed-bed chemical looping

Chemical Looping Hydrogen processes among others, show an outstanding potential for the decentralized conversion of biogas into high-purity hydrogen. For the first time, a 10 kWth fixed-bed chemical looping system has been coupled directly to a 3 MWth biogas digester in the southern region of Austria in the scope of the Austrian research project Biogas2H2. This experimental lab system resembles a blueprint for a potential future industrial system design. A comprehensive parameter study pointed out the influence of relevant process parameters (temperature, O/R ratio, reduction time, steam quantity in oxidation) on hydrogen purity and process efficiency. At the optimal operating point (850 °C, O/R 1.2), the process efficiency was comparable to the utilization of synthetic biogas in previous investigations within a deviation of 2.9%. Sulfuric compounds were isolated before entering the chemical looping system in order to avoid harmful contamination of the product hydrogen and performance loss, as investigated in preliminary experiments.The generated hydrogen was characterized online by ppm-range gas analysis and exhibited a product gas quality of up to 99.998%, with residual CO and CO2 as only contaminants. The fulfillment of the carbon mass balance within a mean deviation of 9% proved the correct quantification. The results indicate that coupling fixed-bed chemical looping systems to biogas plants enables the production of a fuel cell grade hydrogen and a sufficient process efficiency in upgrading local available biogenic and agricultural residuals to high-purity hydrogen.

Protecting ocean worlds: Europa Clipper planetary protection inputs to a probabilistic risk-based approach

AbstractThere is increased interest in exploring planetary bodies that have ocean worlds, and planetary protection (PP) practices for spacecraft are important to avoid harmful biological contamination of these sensitive environments. In the autumn of 2018 a diverse set of subject matter experts were assembled to examine the environmental input parameters (e.g. space radiation, Europa surface turnover) and biological input parameters that are referenced by the Europa Clipper project probabilistic risk model, to assess the < 1 × 10−4 probability of contamination requirement derived from NASA Procedural Requirements 8020.12D. A joint NASA–JPL lead workshop entitled, ‘Europa Clipper Planetary Protection Workshop’ was convened on 13–15 November 2018, to validate probability model input values, current Europa Clipper PP requirements and implementation strategy, and identify future PP research topics. The three objectives for the 3 day workshop were: (1) to validate the probability of contamination modelling framework for Europa Clipper PP; (2) to agree on probability of contamination model input values, or on a plan to derive/identify appropriate model inputs and (3) to develop workshop concurrence regarding future PP research plans and their priority. Workshop participants engaged in detailed scientific and engineering discussions focusing on Clipper mission objectives and trajectories, Europan ice shell geophysics and understanding the impact of initial microbial bioburdens and spacecraft cleanliness with all three objectives being successfully completed by the end of the workshop.

Application of Geochemical Indices in Evaluating Potentially Harmful Element Contamination at Mining Centres in the Sanyati Catchment, Zimbabwe

The release of potentially harmful elements (PHEs) into the environment in mineralised and mining areas has been associated with a variety of health-related disorders, especially non-communicable diseases such as cancer, heart and kidney failure and mental and cardiovascular disorders. The present study sought to evaluate the application of geochemical indices in assessing the degree of contamination at two sites, Kadoma and Hurungwe, both within the Sanyati Catchment, an important mining and agricultural hub in Zimbabwe. This evaluation was conducted by determining the concentration levels of 16 PHEs in 58 top-soil and stream sediment sample locations. The samples were collected during the period 2015–2017 and analysed for total PHE content using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). To assess the degree of contamination of the soils and stream sediments, contamination indices were computed and the potential ecological risk to the area was evaluated. A correlation analysis revealed PHE associations as strongly influenced by lithology and Au mineralisation in the Kadoma setting. Assessment of multi-element contamination using the pollution load index revealed significant contamination in 52% of the soil sample sites and 38% of the sediment sample sites in Kadoma. The results indicate that As, Cr, Mo, and Sb are the main contaminant PHEs in the Kadoma site. Potential ecological risk ranged from moderate to very high at 71% of soil sample locations and 53% of sediment locations and the key contributors were Sb, As, and Hg. At the Hurungwe site, Cr and Mo were found to be key contaminants with a low potential ecological risk for all samples. This study demonstrates the successful application of geochemical indices in evaluating the degree of single and multi-element contamination as the first step toward a human health risk assessment in mining environments. It is expected that these results would assist municipal authorities in their effort to formulate credible mitigative measures to protect the health of nearby residents and surrounding ecosystems and make an informed decision regarding land use planning and post-mining rehabilitation of contaminated land at mining centres.

The Need for Establishing a New United Nations Body to Protect Earth from Back Contamination and Outer Space from Forward Contamination

The purpose of the article is to explore the necessity to establish a new United Nations body, which is authorised to monitor and protect Earth and its organisms from biological contamination from extra-terrestrial sources and to protect outer space from forwarding contamination. Recent studies show that these contaminations could potentially have an extremely detrimental effecton life on Earth and for the safety of future outer space exploration. The study is doctrinal research and primary and secondary legal sources of international space law and environmental law are analysed. The research also applies a theoretical approach to determine what sets of principles should be applied and what intuitional innovation is needed to achieve optimally the goals of improving safety standards. This article presents a proposal for establishing a specialized UN organ to monitor an international agreement for the international planetary quarantine protocol of Earth. The need of establishing a new body in the system of the UN for protection of the Earth’s environment from harmful contamination caused by activities in outer space is quite distinguished. This publication aims also to increase awareness about the need for institutional innovation of the present UN system, particularly concerning global challenges like contamination from outer space and contamination of outer space. One of the major global challenges of today is the absence of safeguards for the protection of Earth from back contamination, an extra-terrestrial source of infection and destruction of space debris on the surface. The proposed new legal instrument would create guarantees for the protection of Earth and the outer space environment, support the adoption of a common space situational awareness system for monitoring and disclosing information about what is happening in outer space.

The Curious Case of Article IX and Outer Space Environment

With the launch of the first artificial satellite, Sputnik, back in 1957, to life on Earth being socio-economically dependent on space technologies, we have come a very long way and with this comes several problems, one being extra-terrestrial pollution. The 1967 Outer Space Treaty has only one provision – Article IX – which merely puts an obligation to avoid ‘harmful contamination’ of outer space. There is nothing in the treaty or elsewhere to suggest the meaning of this term and the extent of protection offered by Article IX, thereby creating a lacuna. The article tries to evaluate whether the interpretation of the term ‘harmful contamination’ has evolved to envisages the implementation of the international environmental law regime for a holistic protection of the outer space environment. In this context, the meaning of ‘harmful contamination’ is analysed as intended by the drafters to highlight the shortcomings. Taking into account the evolving international environmental and space law jurisprudence, the article analyses whether the shortcomings can be addressed by harmoniously interpreting Article IX with the existing environmental law regime. Different tools of treaty interpretation are used to examine the evolving interpretation of the term ‘harmful contamination’ to provide an insight into what the lex ferenda be vis-à-vis application of Article IX in the protection of outer space environment.

The Curious Case of Article IX and Outer Space Environment

With the launch of the first artificial satellite, Sputnik, back in 1957, to life on Earth being socio-economically dependent on space technologies, we have come a very long way and with this comes several problems, one being extra-terrestrial pollution. The 1967 Outer Space Treaty has only one provision – Article IX – which merely puts an obligation to avoid ‘harmful contamination’ of outer space. There is nothing in the treaty or elsewhere to suggest the meaning of this term and the extent of protection offered by Article IX, thereby creating a lacuna. The article tries to evaluate whether the interpretation of the term ‘harmful contamination’ has evolved to envisages the implementation of the international environmental law regime for a holistic protection of the outer space environment. In this context, the meaning of ‘harmful contamination’ is analysed as intended by the drafters to highlight the shortcomings. Taking into account the evolving international environmental and space law jurisprudence, the article analyses whether the shortcomings can be addressed by harmoniously interpreting Article IX with the existing environmental law regime. Different tools of treaty interpretation are used to examine the evolving interpretation of the term ‘harmful contamination’ to provide an insight into what the lex ferenda be vis-à-vis application of Article IX in the protection of outer space environment.

Consistency of attack level of coffee berry borer (Hypotenemus hampei Ferr.) on organic and conventional arabica coffee plantation in Aceh Tengah District, Aceh Province, Indonesia

A study has been conducted for 3 consecutive years since 2019 to 2021 to investigate the influence of cultivation system of Arabica coffee against the attack of the coffee berry borer (Hypothenemus hampei Ferr.) in Arabica coffee plantations in Aceh Tengah District, Aceh Province, Indonesia. We observed the attack level of H. hampei on Arabica coffee plants that were cultivated both organically and conventionally. The results showed that for three years observation, in general, the attack level of coffee berry borer (CBB) on organic and conventional coffee plantations was not significantly different. Observations in 2019 showed that the attack level of CBB on organic coffee plantations ranged from 27-34 % and on conventional coffee plantations ranging from 33-49 %. Observations in 2020 showed that the attack rate of CBB on organic and conventional coffee ranged from 20-40 % and 28-41%, respectively, while observations in 2021 were 25-26 % and 27-28 %. The results of these studies indicate that the level of CBB attack on organic coffee plantations is no different from conventional coffee plantations that routinely use synthetic pesticides. This indicates that in organic coffee plantations, natural enemies have played an important role in suppressing the development of CBB populations. Although the use of synthetic pesticides in conventional coffee plantations can suppress pest populations, it is suspected that these pesticides also play a role in reducing the population of natural enemies of pests. Therefore, organic coffee cultivation is much more profitable, especially it can reduce the cost of buying synthetic pesticides and fertilizers, besides ensuring the safety of coffee farmers, workers, and consumers from harmful chemical contamination from pesticides.

Research in Analog Environments to Enable Studies of Ocean Worlds

Analog environments on Earth enable scientists to answer research questions about extraterrestrial ocean worlds that would be otherwise inaccessible. Because of their relative ease of sampling and close proximity to research facilities, utilization of analog environments allows scientists to undertake many investigations for the cost of a single planetary mission. In addition to direct in situ sampling, modeling approaches can be useful as can cost-effective tools both for determining whether a moon or planet is a suitable Earth analog and for designing strategies to sample extraterrestrial analog environments. Reconfigured Earth system models can help determine if conditions on other ocean worlds are suitable to support life. Finally, space exploration has made the protection of Earth’s environment and other solar system bodies from harmful contamination a high priority at both the national and international levels. Because NASA’s planetary exploration priorities emphasize robotic exploration, the US National Academies recently recommended that studies, workshops, and brainstorming sessions organized by NASA and other space agencies need to include a sufficiently broad range of microbiologists to ensure planetary protection. This will require the development and implementation of mechanisms for creating partnerships between Earth scientists and planetary scientists to test planetary protection solutions at field analog sites.

Environmental Pollution Indices and Multivariate Modeling Approaches for Assessing the Potentially Harmful Elements in Bottom Sediments of Qaroun Lake, Egypt

This research intends to offer a scientific foundation for environmental monitoring and early warning which will aid in the environmental protection management of Qaroun Lake. Qaroun Lake is increasingly influenced by untreated wastewater discharge from many anthropogenic activities, making it vulnerable to pollution. For that, six environmental pollution indices, namely contamination factor (Cf), enrichment factor (EF), geo-accumulation index (Igeo), degree of contamination (Dc), pollution load index (PLI), and potential ecological risk index (RI), were utilized to assess the bottom sediment and to determine the different geo-environmental variables affecting the lake system. Cluster analysis (CA), and principal component analysis (PCA) were used to explore the potential pollution sources of heavy metal. Moreover, the efficiency of partial least-square regression (PLSR) and multiple linear regression (MLR) were tested to assess the Dc, PLI, and RI depending on the selected elements. The sediment samples were carefully collected from 16 locations of Qaroun Lake in two investigated years in 2018 and 2019. Total concentrations of Al, As, Ba, Cd, Co, Cr, Cu, Fe, Ga, Hf, Li, Mg, Mn, Mo, Ni, P, Pb, Sb, Se, Zn, and Zr were quantified using inductively coupled plasma mass spectra (ICP-MS). According to the Cf, EF, and Igeo results, As, Cd, Ga, Hf, P, Sb, Se, and Zr demonstrated significant enrichment in sediment and were derived from anthropogenic sources. According to Dc results, all collected samples were categorized under a very high degree of contamination. Further, the results of RI showed that the lake is at very high ecological risk. Meanwhile, the PLI data indicated 59% of lake was polluted and 41% had PLI < 1. The PLSR and MLR models based on studied elements presented the highest efficiency as alternative approaches to assess the Dc, PLI, and RI of sediments. For examples, the validation (Val.) models presented the best performance of these indices, with R2val = 0.948–0.989 and with model accuracy ACCv = 0.984–0.999 for PLSR, and with R2val = 0.760–0.979 and with ACCv = 0.867–0.984 for MLR. Both models for Dc, PLI, and RI showed that there was no clear overfitting or underfitting between measuring, calibrating, and validating datasets. Finally, the combinations of Cf, EF, Igeo, PLI, Dc, RI, CA, PCA, PLSR, and MLR approaches represent valuable and applicable methods for assessing the risk of potentially harmful elemental contamination in the sediment of Qaroun Lake.

Using Atomically Dispersed Bimetallic Active Sites to Probe the Nitrate Reduction Mechanism to Ammonia

The production of synthetic ammonia via nitrogen reduction is a critical step toward producing fertilizers, central the supporting global food security. To date, the energy-intensive and greenhouse gas-emitting Haber-Bosch process remains the only way to produce ammonia on industrial scale. Recently, significant research efforts have focused on identifying carbon- neutral and distributed pathways to synthesize ammonia, mainly via the electrochemical reduction of dinitrogen (N2).1 This approach, however, is limited by the low N2 solubility, competing hydrogen evolution reactions, and the stability of the N≡N triple bond. A promising alternative pathway to ammonia production is through the reduction of nitrate (NO3 -), a more kinetically and thermodynamically favorable nitrogen precursor. The reduction of nitrate to ammonia provides dual benefits as both a carbon-neutral pathway to ammonia and as a way of denitrification to remove all-too-prevalent and environmentally harmful nitrate contamination, while creating a useful product.2 Although there exists in the literature several works using metal catalysts for the nitrate reduction reaction (NTRR) to ammonia, only very recently have single atom catalysts (SAC) been applied to nitrate reduction.3 , 4 The NTRR is an 8e- transfer reaction, in which the exact electron transfer pathways, either a direct 8e- transfer or by 2 + 6e- pathway, in which a nitrite (NO2 -) intermediate is desorbed and reabsorbed. These processes are not well-studied on SACs. In this talk, we will present a series of atomically dispersed iron and molybdenum, mono and bi-metallic nitrogen doped carbon (M-N-C, M = Fe, Mo, FeMo) electrocatalysts for the NTRR. Our catalysts show potential for faradic efficiencies over 90%, while exhibiting outstanding stability over 48 hours of operation. Furthermore, our results suggest distinct NTRR mechanisms over Fe and Mo active sites, revealing new insights into preferred NTRR pathways over varying single atom sites. Such a detailed understanding of the NTRR electron transfer pathway will not only advance development of high performance, selective SACs, but stands to provide a new route to environmentally responsible ammonia synthesis. References (1) Choi, J.; Suryanto, B. H. R.; Wang, D.; Du, H. L.; Hodgetts, R. Y.; Ferrero Vallana, F. M.; MacFarlane, D. R.; Simonov, A. N. Identification and Elimination of False Positives in Electrochemical Nitrogen Reduction Studies. Nat. Commun. 2020, 11 (1).(2) van Langevelde, P. H.; Katsounaros, I.; Koper, M. T. M. Electrocatalytic Nitrate Reduction for Sustainable Ammonia Production. Joule 2021, 5 (2),(3) Zhu, T.; Chen, Q.; Liao, P.; Duan, W.; Liang, S.; Yan, Z.; Feng, C. Single-Atom Cu Catalysts for Enhanced Electrocatalytic Nitrate Reduction with Significant Alleviation of Nitrite Production. Small 2020, 16 (49).(4) Niu, H.; Zhang, Z.; Wang, X.; Wan, X.; Shao, C.; Guo, Y. Theoretical Insights into the Mechanism of Selective Nitrate-to-Ammonia Electroreduction on Single-Atom Catalysts. Adv. Funct. Mater. 2020, 2008533 (3), 1–8.. Figure 1

Engineering of Plants for Efficient Production of Therapeutics.

Plants are becoming useful platforms for recombinant protein production at present time. With the advancement of efficient molecular tools of genomics, proteomics, plants are now being used as a biofactory for production of different life saving therapeutics. Plant-based biofactory is an established production system with the benefits of cost-effectiveness, high scalability, rapid production, enabling post-translational modification, and being devoid of harmful pathogens contamination. This review introduces the main challenges faced by plant expression system: post-translational modifications, protein stability, biosafety concern and regulation. It also summarizes essential factors to be considered in engineering plants, including plant expression system, promoter, post-translational modification, codon optimization, and fusion tags, protein stabilization and purification, subcellular targeting, and making vaccines in an edible way. This review will be beneficial and informative to scholars and readers in the field of plant biotechnology.

Penentuan Titik Pengamatan Optimal Terhadap Kualitas Udara pada Gas Keluaran Diffuser berbasis Internet of Things

Indoor air quality needs attention, especially during the COVID-19 pandemic because the majority of activities are carried out indoors. The air in the room must be protected from the threat of harmful virus and bacterial contaminants. One such innovation is placing diffuser in the room. Diffuser is a device that converts liquid into gas particles in the air. To reduce harmful virus contamination, a natural antiseptic liquid is filled into the diffuser, one of which is papermint essential oil, which can provide freshness in the room. Air quality is monitored with internet of things (IoT) technology so that users can easily control air quality with just a PC/gadget. The gas output from the diffuser is detected by a gas sensor that is connected to the wemos board so that the data can be connected to the internet cloud. To obtain optimal air quality data, the placement of gas sensors in the area around the diffuser as a point of observation needs to be considered because the distribution of gas in the air is influenced by the vertical wind speed in the room, this can affect the quality of the data generated. This study aims to determine the optimal observation point on an IoT-based diffuser so that the resulting air quality data is more accurate. In this study the gas sensor was placed at a distance of 15 and 25 cm from the diffuser. The direction of the gas sensor placement was adjusted according to the angle of the full circle ranging from 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, and 0°. The distribution of gas is influenced by the vertical wind speed in the room causing the air quality data at a vertical angle to always have the same pattern. From the results obtained, the optimal observation point as a reference for the position of the gas sensor to the diffuser is at an angle between 135°-180° as well as at an angle between 315° -0°.

Parameters of the plain weave meshfor the nozzle of a regenerative heat exchanger

Regenerative heat exchangers have disadvantages such as low heat transfer coefficient from the nozzle to the gas and high hydraulic resistance due to the design of the nozzles. Wire-mesh nozzles can eliminate these shortcomings of regenerators. Wire-mesh nozzles have low hydraulic resistance and large heat transfer surface. The process of heat and mass transfer in a regenerative heat exchanger is considered. A series of numerical simulation experiments was performed. Theoretically, the optimal configuration of the nozzle was calculated: a plain weave mesh with a wire diameter of 0.4 mm, a weaving step of 2 mm, and a step of placing nets of 1 mm. The operational modes for the regenerator are considered, taking into account the period for drying the nozzle from moisture and the maximum mass of water that can hold the nozzle without the formation of drops. Given the condensation of moisture on the nozzle, the following assumptions are made: There is no temperature and concentration inhomogeneity in the cross section of the regenerator channel; The effect of thermal conductivity in the axial direction in contact between the nozzle elements on the temperature profile of the nozzle is insignificant; The time over which the regenerator is operated between the nozzle drying periods is quite short, and the thickness of the condensate layer does not affect the hydrodynamic mode of the heat regeneration process and the value of the heat transfer coefficient. The duration of the cooling and drying period depends on the humidity of the inlet air and the area of the nozzle. This is due to the need to prevent the accumulation of moisture in the device, which can lead to the reproduction of harmful bacteria and contamination of the nozzle. In the SolidWorks Flow Simulation application, simulation experiments were performed for a regenerator model accounting for the influence of compressed air motion resulting from grouped location of the nozzle elements, and the results are shown in the figures. Comparison of the results from analytical calculations and simulation experiments showed the efficiency of the mathematical model and the possibility of its use in the design calculation of regenerators. Correlation dependences have been established to determine the heat transfer coefficient and hydraulic resistance depending on the hydrodynamic conditions. The mathematical and physical model taking into account the condensation of moisture on the nozzle has been specified. Calculations have been performed for the optimal nozzle made in the form of a plain weave mesh with a wire diameter of 0.4 mm, a weaving step of 2 mm, and a step of placing nets of 1 mm.