We conducted this meta-analysis to systematically assess the diagnostic performance of ΔScvO2 during a fluid challenge for fluid responsiveness in mechanically ventilated patients receiving volume expansion.Since oxygen content and oxygen consumption typically remain unchanged within a short period, variation in central venous oxygen saturation  as the primary measure of diagnostic accuracy. The optimal threshold of ΔScvO2 and the corresponding 95% confidential interval (CI) were also estimated.Electronic databases were systematically searched to identify relevant studies published before October 24, 2022. As the cutoff value of ΔScvO2 during the fluid challenge exhibited excellent performance for defining fluid responsiveness in mechanically ventilated patients receiving volume expansion, with an AUHSROC of 0.86 (95% CI 0.83–0.89), a pooled sensitivity of 0.78 (95% CI 0.69–0.85), a pooled specificity of 0.84 (95% CI 0.72–0.91), and a pooled diagnostic odds ratio of 17.7 (95% CI 5.9–53.2). The distribution of the cutoff values was nearly conically symmetrical and concentered between 3 and 5%; the mean and median cutoff values were 4% (95% CI 3–5%) and 4% (95% CI not estimable), respectively.This meta-analysis included 5 observational studies comprising 240 participants, of whom 133 (55%) were fluid responders. Overall, the ΔScvOIn mechanically ventilated patients receiving volume expansion, the ΔScvO2 during the fluid challenge is a reliable indicator of fluid responsiveness.Clinical trial registration PROSPERO, https://www.crd.york.ac.uk/prospero/, registry number: CRD42022370192.The online version contains supplementary material available at 10.1186/s13054-023-04480-z. Thus, the assessment of fluid responsiveness is a crucial procedure before fluid infusion. Seeking reliable surrogate indicators of fluid responsiveness has always been an important research issue in critical care medicine. As fluid responsiveness is usually defined by a significant increase (≥ 15%) in CO after receiving a certain amount of fluid within a short period   were fluid responders. All included studies reported the cutoff value of ΔScvO2 level.As two studies , 22 used2 during the fluid challenge for fluid responsiveness in mechanically ventilated patients receiving volume expansion. The principal findings indicated that the ΔScvO2 during the fluid challenge is a reliable indicator of fluid responsiveness, and the range of 3–5% may represent its optimal CI for evaluating fluid responsiveness.This systematic meta-analysis of 5 observational studies evaluated the diagnostic accuracy of the ΔScvO2 in defining fluid responsiveness. As a potential marker of fluid responsiveness, ΔScvO2 has several advantages over conventional variables. First, tracking the changes in ScvO2 during a fluid challenge can not only assess the response of CO to a fluid bolus but also evaluate the metabolic efficacy of fluid administration. Furthermore, unlike other dynamic variables associated with heart–lung interactions, ΔScvO2 would not, in theory, be affected by arrhythmia, tidal volume, or lung compliance [2 has the potential to become a surrogate marker of fluid responsiveness when CO measurement is unavailable or not applicable. However, before the wide application of ΔScvO2 in clinical practice, some prerequisites should be recognized. According to the simplified formula [2 is estimated as arterial oxygen saturation (SaO2)–VO2/(1.34 × hemoglobin × CO), where SvO2 can be substituted by ScvO2 given the good correlation between the two variables [2 after volume expansion can theoretically track the fluid-induced changes in CO as long as SaO2, VO2, and hemoglobin keep unchanged during the fluid challenge. However, the assumption that hemoglobin keeps unchanged during the fluid challenge is not always true. Administering large volumes of fluids within a short period will inevitably result in a decreased hemoglobin concentration. Previous studies have demonstrated that the hemoglobin concentration was decreased by 6–9% after a 500 mL of fluid challenge [2 after volume expansion . The negative effect of the reduced hemoglobin concentration might result in an underestimation, not overestimation at least, of the diagnostic performance of ΔScvO2 for fluid responsiveness.To the best of our knowledge, this is the first systematic meta-analysis to explore the diagnostic accuracy of ΔScvOmpliance . Therefo formula , SvO2 isariables . Thus, thallenge , which whallenge . Accordi2 is not always constant during volume expansion. Numerous studies found the VO2/DO2 dependency phenomenon in septic patients when DO2 was increased through administrating fluid [2/DO2 dependence stage, VO2 and DO2 would change linearly, and ScvO2 would be unchanged despite the fluid-induced increase in DO2 because of the relatively constant oxygen extraction, and thus might not reflect the fluid-induced changes in CO [2 will not be a reliable marker of fluid responsiveness if oxygen metabolism is in the VO2/DO2 dependency state. However, the above-mentioned theoretical conjecture does not imply the invalidity of ΔScvO2 to evaluate the cardiac response to a fluid bolus, because the pathologic DO2/VO2 dependency phenomenon might be not always common in critically ill patients. For example, in the study by Xu et al. [2 immediately after fluid challenge; other studies [2 increase did not lead to a significant increase in VO2. In this case, selecting the appropriate cohort to utilize ΔScvO2 to define fluid responsiveness would be an interesting issue. Since DO2 decreases below the critical value and cannot meet oxygen demand, oxygen debt will be produced at the VO2/DO2 dependency stage, resulting in an elevated lactate level [2 to define fluid responsiveness and those who cannot. We initially planned to perform subgroup analyses based on the baseline lactate level. However, the scheduled plan of conducting stratified analysis was abandoned due to the limited included studies. Hence, this hypothesis should be verified in future research.Likewise, VOng fluid –28. Theoes in CO . In otheu et al. , only 2  studies , 20, 30 te level , 29. In 2 is slightly higher or lower than the cutoff value, it is difficult to judge whether the patient will benefit from volume expansion. Hence, we estimated the optimal cutoff value as well as its corresponding CI to overcome this limitation. According to the estimated CI and the Bayes nomogram, we established a feasible decision-making algorithm: (1) if the measured ΔScvO2 is greater than 5%, the patient is expected to have a probability of 83% to be a fluid responder; (2) the probability of being fluid responder will decrease to 21% if the measured ΔScvO2 is less than 3%; and (3) if the measured ΔScvO2 is between 3 and 5%, the fluid responsiveness is difficult to determine; in this case, other methods are suggested to assess fluid responsiveness.This meta-analysis presents a major methodological strength that the 95% CI of the optimal cutoff value was estimated to avoid the binary constraint of a “black-or-white” decision of the ROC curve and fit the reality of clinical or screening practice. In a realistic clinical decision-making scenario, a single threshold seemly cannot meet the demand of defining fluid responsiveness. For instance, if the measured ΔScvO2 level may be associated with the diagnostic performance of ΔScvO2; the fluid type  might cause a potential bias in the results because of the different volume expansion power. Second, all of the included studies had low methodological quality. Of note, two studies [2 using a point-of-care blood gas analyzer [2 can evaluate fluid responsiveness in patients with spontaneous breathing. Theoretically, ΔScvO2 can also reliably evaluate fluid responsiveness in patients with spontaneous breathing as long as they stay quiet during the fluid challenge so that VO2 will not be affected by other factors (such as emotion or activity).Several limitations in our study should be acknowledged. First, the limited included studies and the relatively small sample sizes (240 patients) represent the primary limitation, resulting in a decreased statistical power that hampered us from drawing a firm conclusion. Furthermore, studies with a small sample size may overestimate the effect sizes. Additionally, several subgroup analyses were not performed due to the limited included studies. For instance, the baseline lactate level and ScvO studies  might in studies , the senanalyzer , which c2 during the fluid challenge is a useful and reliable approach to evaluate fluid responsiveness. The range of 3–5% may represent the optimal confidence interval of ΔScvO2 to define fluid responsiveness. Given the low methodological quality of the included studies, larger studies with high methodological quality are warranted to validate the applicability of ΔScvO2 in evaluating fluid responsiveness.In mechanically ventilated patients receiving volume expansion, the measurement of ΔScvOAdditional file 1: Table S1. Detailed searching strategies in each database. Table S2. Detailed diagnostic accuracy of ScvO2 variation for evaluating fluid responsiveness. Figure S1. Sensitivity analysis to assess the robustness of ScvO2 variation for defining fluid responsiveness by excluding studies introducing a high risk of bias


TRAcking non-small cell lung Cancer Evolution through therapy (TRACERx), a large-scale study headed by Charles Swanton in the UK, set out to understand the evolutionary trajectories and their clinical consequences in NSCLC. The recent papers now published findings of the first 421 prospectively recruited patients with early-stage NSCLC. To characterise ITH, tumour evolution and its relation to clinical outcome, tumours were analysed in a multimodal approach utilising genomic, transcriptional, and histological profiling. Each method was applied independently to multiple tumour regions per sample to fine-map ITH and -where available- to primary tumours, metastases and relapsed tumours. They also studied circulating tumour DNA and body composition to investigate the relationship between molecular alterations and cachexia and investigated the role of B cells in anti-tumour immunity  and genetic shifts during a tumour’s life history and progression still present major challenges to treatment.9 whole-exome sequencing of 1644 regions from 421 primary tumours showed that high ITH of somatic copy number alterations but not of point mutations was associated with shorter disease-free survival.1 Similarly, subclonal whole genome doubling was significantly associated with shorter DFS while clonal whole genome doubling did not show such an association.1 Assessment of transcriptomes identified a set of highly expressed cancer genes with minimal transcriptional ITH, which also showed genetic evidence of being positively selected during tumorigenesis. Comparison of selection signals between truncal and subclonal mutations in cancer genes allowed mapping the role of these genes to early or late tumour evolution. Significant subclonal but not truncal alterations affected known driver genes such as PTEN in lung adenocarcinoma, indicating a role in late rather than early tumour evolution.2 Positive selection of subclonal mutations was observed to be stronger in cases of clonal illusion, i.e. one subclone dominating a tumour region and evidence of recent subclonal expansion. Phenotypically, tumours with recent subclonal expansion were highly proliferative and displayed high-grade growth patterns histologically.3 Interestingly, recent subclonal expansion was significantly associated with shorter disease-free survival,1 suggesting that subclonal dynamics are major determinants of clinical trajectories.Consistent with previous findings,NRAS, TP53 or RBM5, recent subclone expansion or a highly proliferative phenotype.4 While most metastases are seeded by a single clone, polyclonal seeding is an additional risk factor associated with extra-thoracic disease recurrence and poor clinical outcome.4 The true rate of polyclonal seeding however is challenging to judge owing to potential undersampling of metastases e.g. due to inaccessible metastatic location. To mitigate this limitation, the TRACERx group developed a novel approach to derive subclonal structure of recurring tumors using circulating tumour DNA (ctDNA).5 Analysis of ctDNA could furthermore be utilised to detect cases of polyclonal seeding. Matched pre- and postoperative profiling ctDNA revealed that subclones which are detected postoperatively are already expanded before surgery, as indicated by higher preoperative cancer cell fractions. Since the postoperatively detectable subclones are reflective of recurrent disease, the preoperative cancer cell fraction might inform about the metastatic potential of a specific clone and can be utilised to predict metastasis.5To identify evolutionary patterns associated with progression, 126 patients with paired primary tumours and lymph node metastasis tissue in the TRACERx cohort were identified. Among primaries and metastases, the majority (68.9%) of driver mutations were shared, whereas 75% of metastases diverged late, i.e. after the last subclonal expansion  in the primary tumour. In case of early divergence, simulations suggested that these metastases likely derive of tumours smaller than 8 mm in diameter, a typical size threshold in computed tomography to trigger further investigation. Overall, metastases are more likely seeded from the primary tumour than from existing metastatic sites. Comparing seeding and non-seeding clones of the primary tumour revealed distinct genomic and phenotypic characteristics like mutations in 6 CT scans at surgery and again at disease relapse were used to identify patients that developed cachexia and those that did not. Analysis revealed that primary tumours of cachexia patients had increased inflammatory and epithelial-mesenchymal transition signalling as well as genomic alterations in known cachexia candidate genes. Plasma proteome profiling suggested GDF15 as a potential circulating mediator of cachexia.6 While the direction of causality remains to be determined, these molecular profiles could help to identify patients with high risk of cachexia.Expanding beyond tumour evolution, the TRACERx team used their molecular data to predict the onset of cachexia, a severe, frequently seen complication of advanced tumours marked by fat and muscle loss.7 In mouse models and patient samples, they discovered B-cell proliferation in tumour-adjacent tertiary lymphoid structures (TLS) that were increased by immunotherapy and KRAS inhibition. Presence of TLSs has been correlated with improved immunotherapy outcomes previously, but the reasons were unclear. Surprisingly, the B-cell antibodies did not target tumour-specific neoantigens, but instead bound envelope proteins of endogenous retroviruses (ERVs), which are retroviral sequences embedded in human DNA that can reactivate in cancer cells. ERV-reactive antibodies prolonged survival in mice and correlated with immunotherapy-response in lung cancer patients, potentially providing a novel mechanistic link between TLSs and immunotherapy response.Furthermore, TRACERx researchers explored the relationship between cancer treatment and anti-tumour immune response.Overall, the multi-omic analysis of this prospective, extensively sampled NSCLC patient cohort provides unparalleled insights into the complexity of tumour architecture and evolution. It emphasizes the vital relevance of clonal dynamics regarding disease progression and underscores the need for ongoing disease assessment to refine treatment approaches. Simultaneously, TRACERx pioneers new strategies, such as utilizing molecular data for cachexia prediction or inferring tumour evolution and clonality from ctDNA. It thereby provides a rich resource of data, methods and hypotheses for follow-up analyses and experimental studies investigating mechanistic connections between genetics, evolutionary dynamics and disease progression.


Vegetable content of all available recipes within a 1-week period were analysed. Our findings highlight the rapid expansion and evolution of MKSS market offerings over the past decade and their potential to support family vegetable consumption. Across all analysed recipes (n = 179), MKSSs provided a median of 2.5 vegetable serves per person (range 0.7–7.5 serves) and a median of 3 different types of vegetables from 2 vegetable subgroups . This suggests that MKSSs may support family vegetable consumption if families select recipes with a greater number and variety of vegetables. However, an opportunity remains for MKSSs to improve both vegetable quantity and variety to positively influence population health. Further research is required to describe how families use meal kits promoting a greater understanding of their potential to improve family nutrition.Popular commercial meal kit subscription services (MKSSs) may support families to overcome barriers to cooking and eating at home, and facilitate improved vegetable consumption. The global meal kit market has expanded rapidly creating a gap in our understanding of the health-promoting potential of MKSSs. This paper describes the contemporary MKSS market in Australia and provides a vegetable-specific content analysis of a sample of recipes. A 1-week subscription was purchased for all Australian-based MKSSs ( Provides new insights regarding the Australian meal kit market including growth and diversity of offerings across a wide range of price points.Quantifies vegetable serve numbers and variety across nine meal kit companies providing insights into opportunities to meet daily vegetable recommendations.Examines opportunities to leverage this knowledge to support users to maximize vegetable consumption.Globally, people consume insufficient quantities of vegetables, fruit and wholegrains  and dietThe Australian Dietary Guidelines (ADGs) recommend children consume 2.5–4.5 serves of vegetables  per day, increasing to 5 or more serves in adulthood, to promote optimal nutrition . The ADGThe family meal environment presents an opportunity to influence vegetable intakes of adults and children. In many countries including America  consumptParents frequently report barriers to cooking and eating at home such as a lack of time, energy and skills/knowledge  are increasingly popular, expanding rapidly across the globe and Australia in the past decade  includinn = 16) from Australian families reported that MKSSs decreased food-related decision-making fatigue and mental load  by reducing common barriers to family meal provisioning (n = 13) (n = 16) . Qualitative interviews with families from Denmark (n = 13)  to Austr(n = 16)  and incl(n = 16) , while tThese findings suggest that MKSSs may have the potential to positively influence family vegetable intakes. However, a gap exists in our current knowledge of the Australian market due to the dynamic nature of MKSSs (38–40). A greater understanding of the contemporary market, including products and services, is required to gain a complete picture of their potential to be harnessed as a health-promoting tool. Furthermore, given MKSSs offer many opportunities known to influence vegetable consumption, an exploration of the vegetable quantity and variety of all Australian MKSSs provides insights into the market’s potential to improve family vegetable consumption. Therefore, the aim of this study is to provide a comprehensive overview of MKSSs in Australia and to assess the vegetable content of a sample of recipes.A structured search using Google Chrome and Boolean logic was conducted in March 2022 to identify MKSSs operating in Australia. Search terms included a combination of: ‘meal kits’, ‘food boxes’, ‘recipe box’, ‘delivery’ and ‘subscription services’. MKSSs were defined as a subscription service that delivers predominately fresh, pre-measured ingredients paired with recipes and directly to consumers to prepare at home. Services that did not involve home meal preparation and cooking  were excluded.n = 4), a co-author or research assistant was the recipient. Ethics approval was not required for this study as data were publicly available and did not include human participants.A 1-week subscription which included the delivery of a ‘meal kit’  was purchased between May and June 2022 from each provider enabling access to website content and recipes that are only available with a paid subscription. For pragmatic reasons, the number of meals and servings ordered by the primary author (K.F) was based on the minimum serving requirements across all MKSSs . Purchasing of meals provided the opportunity to access all recipes within each MKSS from which we sampled 1 week of recipes . The recipes received in the meal kit deliveries were not the subject of data analysis, therefore the meals delivered were chosen based on personal preference. Where the MKSS did not operate in the primary author’s (K.F) hometown , meal types (i.e. vegetarian) and extra services .For each MKSS, all recipes available in a 1-week period between April and May 2022 were downloaded from MKSS websites as a sample for that provider. Data extracted from recipes included key features such as inclusion of nutritional information, number of ingredients and cooking steps, visual presentation (i.e. ingredients and/or cooking steps) and preparation time.The vegetable variety of each downloaded recipe was extracted into a specifically designed Microsoft Excel spreadsheet. Data were recorded for the number of different types of vegetables within the ingredient list and the number of different vegetable subgroups represented. For example, if a recipe included one carrot and half a pumpkin, this was recorded as two different types of vegetables but one vegetable subgroup (i.e. red- and orange vegetables). The definition of ‘vegetables’ used follows the ADGs, which includes all fresh unprocessed  or minimally processed vegetables (including canned legumes/beans), with the exception of tofu which is classified as a ‘meat alternative’ . The fivData documented from meal kit deliveries was used in the analysis only for cross-checking purposes (e.g. checking Foodworks vegetable weights). A standardized data collection protocol was used to extract data and document the recipes and ingredients received in the ‘meal kit’ deliveries. This included taking photographs of recipe cards and ingredients provided for each MKSS delivery. Vegetables were weighed using kitchen scales to the nearest gram.The weights of all ingredients for each downloaded recipe were entered by the primary author (K.F) into an Australian nutritional analysis software program, Xyris A standardized protocol and coding rule hierarchy were developed, informed by other studies . Product nutrition information panels were utilized to calculate drained weight of canned/jarred vegetables (e.g. chickpeas). Additional information was obtained from supermarket websites as required (i.e. number of ‘spring onions’ in one bunch). Vegetable ingredients/foods classified as ‘discretionary’ by the ADGs  and natiWhere an ingredient weight was provided in the recipe, that was the weight entered in Foodworks. More commonly, vegetables were referred to in recipes by unit description (e.g. ‘1 carrot’ or ‘2 potatoes’). To standardize data entry, the FoodWorks ‘medium’ portion size was applied. Cross-checking of Foodworks medium weights with meal kit delivery samples identified three instances where Foodworks ‘medium’ size was >50% larger than the average recorded weight of vegetables received during meal kit deliveries, and in these instances the latter weight was utilized. This was applied to sweet potato (269 g per potato was entered), capsicum (130.5 g edible portion per capsicum was entered) and leek (99 g per leek was entered).n = 7) and was not available in Foodworks, therefore the average weight of three cos lettuces (223 g) received during meal kit delivery was applied in these instances. For vegetables on downloaded recipes that were not received during meal kit delivery (i.e. could not be weighed), the quantity was sourced from other MKSS recipes and the average was applied. For example, the weight of cauliflower reported on five recipes was averaged (300 g) and applied to two recipes with unspecified cauliflower quantity.For vegetables with quantities not specified and unavailable in Foodworks , the quantity applied during data entry was sourced from the average weight recorded during meal kit deliveries. For example, the weight of ‘cos lettuce’ was not specified on MKSS recipes (n = 14) and >5.0 vegetable serves per person (n = 25). Any discrepancies in FoodWorks outputs  or uncertainties in coding were discussed and resolved by the coders (K.F and A.S).All coding was conducted by the first author (K.F). A second author (A.S), a dietitian with prior experience using FoodWorks, conducted a cross-check of 39 recipes (20%) at both extremes of the distribution, that is <1.0 vegetable serve per person . Since we could not access a full week of recipes for these MKSSs , these were included in the meal kit description data but excluded from vegetable content analyses. Therefore, of the 231 recipes on offer in a 1-week period across the nine MKSSs , 179 recipes were included in the analysis.n = 6). Both continuous variables (i.e. vegetable serves per person) and categorical variables (i.e. vegetable serve categories) are represented for all recipes (n = 179), vegetarian/vegan recipes (n = 57) and non-vegetarian/vegan recipes (n = 122). Vegetable type and subgroup variety are reported for each MKSS including the proportion of recipes with vegetables from each of the five FoodWorks subgroups.n = 179), the median number of vegetable serves per person was 2.5, and ranged across services from 2.0 serves for Dinnerly™ up to 3.2 serves for Marley Spoon™ (n = 57) of all recipes were vegetarian/vegan and provided a median of 3.1 vegetable serves per person across the MKSSs, ranging from 2.3 for Dinner Twist™ to 5.6 for HelloFresh™.Across all analysed recipes (y Spoon™ . Thirty-n = 68) of ‘all recipes’ (n = 179) included <2.0 standard serves of vegetables per person. Non-vegetarian/vegan meals contributed to a greater proportion of these recipes (43%) and vegetarian/vegan recipes (27%) contributed the least. This ranged across services from 23% (Dinnerly™) of non-vegetarian/vegan recipes with vegetable quantities below 2.0 standard serves to 63% (Marely Spoon™) of non-vegetarian/vegan recipes.When assessed as a categorical variable, there was notable variability in the proportion of ‘all recipes’ providing high or low vegetable quantities across the different MKSSs. For example, the proportion of all recipes from each MKSS with vegetable serves >3.1 ranged from 63% (Marley Spoon™) to 20% (Dinnerly™). Thirty-eight percent (n = 89), tomatoes  (n = 76), onion  (n = 76) and carrots (n = 67). Garlic (n = 114) was the most frequently provided flavouring, followed by fresh herbs (n = 74), tomato paste (n = 24) and spring onion (n = 22).Across the MKSSs, analysed recipes provided a median of 3 different types of vegetables per recipe, ranging from 1 to 6 vegetable types . The mosn = 179)  . The proTo our knowledge, this is the first study to comprehensively document the Australian MKSS market and provides the first vegetable-specific analysis of MKSS recipes offered over a 1-week period. With inclusion of nine MKSS, our findings highlight the rapid growth and expansion of the Australian MKSS market. Over the past decade, four multi-national and five locally owned MKSSs have emerged in Australia, the most recent established in 2020. The first Australian MKSS paper (published in 2019)  describen = 15) included <2.0 serves of vegetables per person. Furthermore, 43% of non-vegetarian/vegan recipes (n = 53) also included <2.0 vegetable serves per person. The variability in vegetable content of recipes is an important finding if families are relying on these meals to provide a healthy diet. Australian households typically consume a high proportion of their daily vegetables during the evening meal  and low in fibre (This study provides a contemporary overview of the rapidly evolving MKSS market in Australia and highlights the potential for harnessing MKSSs to influence family vegetable consumption. From a nutrition perspective, our findings highlight that MKSSs may support families in meeting daily vegetable recommendations, particularly if families select recipes with a greater number and variety of vegetables. However, an opportunity exists for researchers to work with MKSSs to strengthen their opportunity to market healthy meals and to improve the vegetable quantity and variety of meals. Combined with the many opportunities known to influence vegetable consumption, such as enabling home cooking and facilitating food literacy development, MKSSs may be a viable mechanism to support family mealtime vegetable consumption. However, there is a need for further research to explore how families, especially those with young children, use meal kits, to better understand the potential of MKSSs to improve family nutrition.


Moreover, 62.34%, 16.88%, and 11.26% of the utilized nanofluids have volume fractions between 0 and 0.5%, 0.5 and 1%, and 1 and 2%, respectively. The twisted tape is the most widely employed of various inserts, with a share of about one-third. Furthermore, the highest achieved flat plate solar collectors’ thermal efficiency with turbulator is about 86.5%. The review is closed with a discussion about the recent analyses on the simultaneous use of nanofluids and various inserts in flat plate solar collectors. According to the review of works containing nanofluid and turbulator, it has been determined that the maximum efficiency of about 84.85% can be obtained from a flat plate solar collector. It has also been observed that very few works have been done on the combination of two methods of employing nanofluid and turbulator in the flat plate solar collector, and more detailed work can still be done, using more diverse nanofluids (both single and hybrid types) and turbulators with more efficient geometries.This paper reviews the impacts of employing inserts, nanofluids, and their combinations on the thermal performance of flat plate solar collectors. The present work outlines the new studies on this specific kind of solar collector. In particular, the influential factors upon operation of flat plate solar collectors with nanofluids are investigated. These include the type of nanoparticle, kind of base fluid, volume fraction of nanoparticles, and thermal efficiency. According to the reports, most of the employed nanofluids in the flat plate solar collectors include Al The worldwide need for energy goes up constantly. Increasing the energy demand has got up the consumption of fossil fuels. Due to the supply of energy resources, environmental considerations, the use of petrochemicals and the increasing price of fossil fuels, and technological progress, developing and developed countries have a particular view on renewable energy. Converting a natural phenomenon into a proper type of energy is defined as renewable energy technologies. One of the factors that can be stated for using renewable energy instead of fossil energy is the issue of reducing the emission of toxic gases and keeping the environment safe . This classification includes solar collectors with low temperatures (temperatures less than 100 ℃), medium temperatures (temperatures between 100 and 300 ℃), and high temperatures (temperatures more than 300 ℃) , effortless installation, and lower cost than other models  are reported to be 670,000 m2  or when a concentrated beam of light is needed.  is an aerodynamic machine, including a small vane generally connected to a lifting plate. In the attendance of winglets and vortex generators, the resulting rotational flow leads to the appropriate dispensation of temperature in both the longitudinal and radial directions . Among the applications of nanoparticles, we can mention the increase in thermal and chemical resistance and improvement in the strength of the produced materials. The nanoparticles’ high surface-to-volume ratio is another one of the properties of this material Izadi . ConformThere are generally two single-phase and two-phase models in the modeling process of nanofluid flow in FPSCs. In the first one, the base fluid and nanoparticle are formed into a single-phase fluid, and thermos-physical properties varying with temperature have been presented according to the experimental outcomes of various research (Izadi and Assad Assuming nanofluids to homogenized (single phase) mixtures, the following equations are often used to approximate the thermophysical properties , and after that, CuO is in second place (12%). It should also be noted that the number of investigations on using combined nanofluid in FPSCs is relatively high during the last 8 years (about 10%).Figure Figure Different assessments have been conducted to facilitate the thermal performance of flat plate solar collectors. This study aims to assess the current two methods, including nanofluids and inserts (enhancement devices), to improve the thermal performance of FPSC.In total, attaining better heat exchange rates is one of the original targets in industrial applications. By adding nanoparticles to the base fluid and creating a nanofluid, the conductivity of the working fluid may be increased. According to prior analyses, using nanoparticles and investigating the concentration, size, and types of nanoparticles have led to a noticeable improvement in thermal efficiency  is in the range of 0–0.5.Furthermore, as indicated by the research presented in this study, particularly in non-experimental analyses, there are instances where various outcomes have been reported. These discrepancies may stem from several sources, containing simulation errors and calculation, as well as potential inaccuracies in the measurement process.As stated in the previous sections, new methods, including confusing agents, have been implemented to elevate heat exchange in various thermal systems. In the following, some research focusing on ways to ameliorate and optimize the heat exchange rate in flat plate solar collectors is given along with the insert.In 2000, Kumar and Prasad  Martín et al. Using a twisted tape, Ananth and Jaisankar , to increase the thermal performance of FPSC. Inserts such as twisted tapes, wire coils, and turbulator improve heat transfer by increasing turbulence and swirling flow and decreasing the thickness of the boundary layer. Garcia et al. . Inserts, strategically placed within the collectors, have illustrated promising potential to go up their thermal efficiency. In this study, several factors are essential to understanding the effectiveness of using inserts in FPSCs, containing the type of study, the variety of employed inserts, and the assessment of thermal efficiency. Using inserts in FPSCs represents an approach to ameliorating heat exchange and thermal efficiency. Researchists have conducted many studies in this domain, utilizing experimental and non-experimental methods. By exploring the findings of these studies, valuable insights into the benefits and limitations of incorporating inserts into FPSC can be gained.A varied range of inserts has been used to improve the thermal efficiency of FPSCs. These inserts come in different configurations and materials, each presenting unique heat exchange and flow increase characteristics. Some usual insert examples consist of twisted tapes, fins, and vortex generators, among others. Furthermore, this part examines the synergistic impacts of combining various kinds of inserts within FPSCs. Researchers have investigated diverse combinations of inserts to realize how they interact. In conclusion, integrating inserts into flat plate solar collectors illustrates a great way to enhance thermal efficiency and improve energy conversion.Over the past decade, a significant trend in solar collectors has been the growing adoption of inserts to enhance and improve heat transfer, even at the expense of increased pressure drop. As mentioned in “Type of the employed inserts in FPSCs,” twisted tape is the most popular insert for researchers due to its simplicity and well-established manufacturing processes.In fact, the implementation of inserts introduces a transformative influence on the flow regime and structure within the flat plate solar collectors. Each unique insert geometry brings about a distinct alteration, offering various approaches and methodologies for researchers to check. The versatility and adaptability of inserts contribute to a wealth of possibilities, making the future of research in this field significantly more precise and promising. As researchers continue to delve into novel shapes and configurations of inserts, the potential for further advancements and breakthroughs in enhancing heat transfer within flat plate solar collectors becomes increasingly evident. Thus, pursuing new and varied insert designs holds the key to unlocking even more significant potential in this area of research.Sometimes two or more active and passive approaches are used to meliorate thermal performance, producing higher heat transfer rates than would be provided by either technique individually. In the following, some research is given on ways to ameliorate and optimize the heat exchange rate in flat plate solar collectors, including inserts and nanofluids.Sandra et al.  inside the flat plate solar collector causes the formation of swirling and secondary flows in the fluid flow. Then, the swirling flow increases heat transfer between the working fluid and the collector. The investigations have shown that different types of turbulators have been used to enhance heat transfer in the collector model, and positive results have also been announced, which shows the importance of using the desired method in improving the collector’s thermal performance. Moreover, the investigations carried out in this work have shown that in a number of articles, both methods of using nanofluid (single or hybrid) and turbulator have been used as passive methods to ameliorate heat exchange in the FPCSs, and the obtained results were promising in enhancing the thermal performance of the collector.