Krukenberg tumours are unusual metastatic tumours of the ovary with primary tumours from the stomach, breast and gastrointestinal malignancies. Krukenberg tumour from pulmonary malignancy represents an extremely rare situation. This is an elaboration of a case of young women with Krukenberg tumour rising from lung adenocarcinoma. A 38‐year‐old woman presented with progressive abdominal distention for the past 2‐years. Computed tomography (CT) of thorax, abdomen and pelvis revealed a huge ovarian mass with left lung nodules and left‐sided pleural effusion. A detailed immunohistochemical staining on pleural fluid cytology confirmed the diagnosis of metastatic adenocarcinoma of lung origin. She underwent doublet platinum chemotherapy as molecular testing for oncogenic mutation was negative. The patient responded well to chemotherapy with a significant reduction in ovarian tumour size. Early identification of the primary source of Krukenberg tumour is paramount to avoid invasive diagnostic surgical intervention for ovarian metastasis. Krukenberg tumour from pulmonary malignancy represents an extremely rare situation. This is an elaboration of a case of young women with Krukenberg tumour rising from lung adenocarcinoma. Krukenberg tumour is a metastatic ovarian cancer characterized by mucin‐rich signet‐ring adenocarcinoma.A 38‐year‐old woman presented with a 2‐year history of progressive abdominal distension. She noticed abdominal fullness the size of a tennis ball, which subsequently progressed to the size of a soccer ball. She has no known medical illness. The patient has never smoked and has no history of exposure to secondhand smoke. She has been a full‐time housewife with no history of occupational exposure to carcinogens. She is nulliparous with a regular 28‐day cycle of a menstrual period.Abdominal examination revealed a huge immobile suprapubic mass up to 30 weeks in size. Chest examination demonstrated reduced air entry and vocal resonance over the left lower zone chest wall with stony dullness upon percussion. Breast examination was normal with no palpable breast mass. There was no palpable lymphadenopathy and other systemic review was unremarkable.Gynaecological transabdominal ultrasonography identified a huge ovarian mass with a size of 20 × 20 cm (anteroposterior × transverse diameter). Computed tomography (CT) of thorax, abdomen and pelvis depicts a large solid‐cystic pelvic mass, with bilateral ovarian cysts and left hydrosalpinx. There is a solid irregular lung lesion is seen at the left upper lobe, ipsilateral pleural effusion and multiple bilateral small lung metastases Figure .The patient underwent several procedures to identify the primary source of malignancy. Pipelle tissue sampling was negative for malignancy, and the visualized colon was normal during colonoscopy. Left pleural tapping was performed and cytology showed the presence of neoplastic cells with acinar pattern suggestive of adenocarcinoma Figure . The immFurther molecular testing for lung adenocarcinoma oncogenic mutation was negative for epidermal growth factor receptor (EGFR), Anaplastic lymphoma kinase (ALK) c‐ros oncogene 1, (ROS‐1) and Programmed cell death ligand 1 (PD‐L1). The molecular testing for tumour sample is done via the AmoyDx Pan Lung cancel panel, which is a real‐time PCR assay for qualitative detection of alterations in EGFR, ALK and ROS‐1. The VENTANA PD‐L1 Assay is used to assess PD‐L1 levels with a the qualitative immunohistochemical assay via monoclonal anti‐PD‐L1 clone SP263. To date, she is currently on doublet platinum chemotherapy (cisplatin and pemetrexed), which shows partial response with a significant reduction of ovarian tumour size from 20 × 20 cm to 8 × 10 cm.The exact mechanism of Krukenberg tumour metastasis is still unknown, with three proposed mechanisms including tumour spread via lymphatic system, hematogenous system, and transcoelomic pathway.The diagnostic challenge, in this case, is to identify the origin of adenocarcinoma. Adenocarcinomas are malignant neoplasms arising from epithelial tissue of the glands. The histology includes the identification of pleomorphic nucleoli with a glandular structure under light microscopy.Krukenberg tumour, although rare, should be considered as a differential diagnosis during the investigation of ovarian/pelvic mass as this condition poses a different route of investigation, treatment and prognosis. Traditionally, Krukenberg tumour is diagnosed after oophorectomy or total abdominal hysterectomy with bilateral salpingo‐oophorectomy. In contrast, in our patient's journey to diagnosis, extensive surgical intervention to obtain sample for definitive tissue diagnosis was avoided as there was a less invasive source to be sampled, which is the left pleural effusion. Although we lack definitive histological proof of ovarian metastasis, the patient's cytomorphology and immunohistochemistry profile suggest adenocarcinoma of lung primary with ovarian metastasis. Our tumour board meeting agreed that the typical moth‐eaten cysts appearance of the ovary supports this diagnosis. To date, the patient has shown a significant reduction in ovarian tumour size in response to chemotherapy, indicating good treatment response without extensive surgical intervention.Since the Krukenberg tumour is a metastatic disease from other organs, it is classified as a stage IV disease, that carries a poor prognosis.In conclusion, early identification of the primary source of the Krukenberg tumour is paramount to avoid invasive diagnostic surgical interventions for ovarian metastasis. Furthermore, adequate IHC staining is useful in confirming the origin of metastatic adenocarcinoma.All listed authors contributed to the article.None declared.The authors declare that appropriate written informed consent was obtained for the publication of this manuscript and accompanying images.


Pseudomonas aeruginosa (PA) is an important nosocomial pathogen. In 2023, tobramycin (TM) susceptibility breakpoints for PA were lowered (from ≤4 to ≤1 µg/mL) by the Clinical and Laboratory Standards Institute (CLSI). The purpose of this study was to evaluate whether this change will result in an increase in the proportion of PA clinical isolates that are considered multidrug-resistant (MDR).PA clinical isolates were obtained from patients evaluated at hospitals across Canada (January 2016 to December 2021) as part of an ongoing national surveillance study (CANWARD). Susceptibility testing was carried out using custom broth microdilution panels. MICs were interpreted using current (2023) CLSI breakpoints, with the exception of TM (interpreted using the 2022 and 2023 breakpoints). MDR PA were defined as isolates testing not susceptible at least three of the following: ceftazidime, ciprofloxacin, meropenem, piperacillin-tazobactam, and TM (assessed with both the 2022 and 2023 CLSI breakpoints).1649 PA isolates were included in this study. The proportion of isolates testing susceptible to TM using the 2022 (S ≤4 µg/mL) and 2023 (S ≤1 µg/mL) CLSI breakpoints were 93.6% and 84.8%, respectively. Overall, 21.6% (356/1649) and 22.7% (374/1649) of PA isolates were MDR, using the 2022 and 2023 CLSI breakpoints. Below, the in vitro activities of common antipseudomonal antimicrobials versus PA isolates from this study  are presented.In this dataset, the proportion of MDR PA isolates was minimally altered by a recent change to the CLSI TM susceptibility breakpoints. A reduction in the proportion of PA isolates that were susceptible to TM using the new breakpoints was most pronounced for the MDR subset.George Zhanel, PhD, Avir: Grant/Research Support|Iterum: Grant/Research Support|Merck: Grant/Research Support|Orimed: Grant/Research Support|Paladin Labs: Grant/Research Support|Pfizer: Grant/Research Support|Verity: Grant/Research Support|Zambon: Grant/Research Support


The Funding statement is incomplete. The complete statement is:https://wellcome.ac.uk/what-we-do/our-work/institutional-strategic-support-fund). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This work was supported by the Fondo Nacional de Ciencia, Tecnología e Innovación (FONACIT-Venezuela) (grant G-2005000827 to HJC), the Scottish Funding Council  and grant #204820/Z/16/Z to PS by the Wellcome Trust Institutional Strategic Support Fund (


The machining process of aluminum alloy usually produces built-up edge and tool sticking problems due to their low hardness and large plastic deformation, which may further affect the machined surface quality and tool life. This paper aims to investigate the influence of different cutting fluids on the machined surface quality and tool life during the milling process of 7050 aluminum alloy. A novel cutting fluid (QC-2803) was considered in the study, which is synthesized by addition of alkyl alcohol amide and chlorinated polyolefin, and the traditional cutting fluid (CCF-10) was used as the control group. The physical and chemical properties of two cutting fluids were characterized. The milling process of 7050 aluminum alloy was carried out under two different cutting fluid conditions. The machined surface morphology, cutting force and tool wear morphology were observed during the process. Results show that the surface tension of the novel cutting fluid is significantly lower than that of the traditional cutting fluid, which makes it easier to produce a lubricating film between the aluminum alloy and tool, and further benefits the machined surface quality and tool life. As a result, the surface roughness and cutting force are reduced by ~20.0% and ~42.9%, respectively, and the tool life is increased by 25.6% in the case of the novel cutting fluid (QC-2803). The results in this paper revealed the important laws of cutting fluid with metal surface quality, cutting performance and tool wear, which helps to control the machined surface quality and tool life by the selection of cutting fluid during metal milling. The milling process of aluminum alloy is an intermittent machining process, and the tool is subjected to cyclic impact when cutting in and out, which will aggravate tool wear. Tool wear will further affect the machining quality of the workpiece. Therefore, it is essential to study the tool wear during the machining process of aluminum alloy to improve machined surface quality and tool life.Aluminum alloys have been widely used in aerospace, aviation and other fields due to their high strength, low density, and corrosion resistance . HoweverThe aeronautical aluminum alloy machining process usually produces built-up edges and tool sticking problems due to their low hardness and large plastic deformation. In addition, fusion welding usually occurs on the cutting edge, which may further affect cutting efficiency, surface roughness and machining accuracy of aluminum alloys. Cutting fluids have good cooling and lubricating properties; it is commonly used in metal cutting to effectively reduce machining temperatures, promote chip evacuation, improve cutting efficiency and surface quality . AccordiCurrently, research on cutting fluid is mainly divided into three aspects: the application method of cutting fluid, its influence on machining, and the development of environment-friendly cutting fluid. During cutting process, to reduce cutting temperature and prolong tool life, large amounts of cutting fluid are used, which may damage for the environmental pollution and human health ,9. New a2O3 nanoparticles), and the results showed that compared with dry cutting and conventional cutting fluid, the cutting force was reduced by ~50.0% and ~30.0%, and the Ra value of the nano-cutting fluid processing surface was reduced by ~54.5% and ~28.5%, respectively, which prolonged the tool life. Su et al. [2) cutting methods, and the results indicated that compared with dry machining, the cutting zone temperature under LCO2 cutting conditions is reduced by 80%, tool wear is reduced by 5%, and cutting force modulus is reduced by 5%. Pereira et al. [2 cryogenic and MQL technique, and the results showed that tool life was extended to 50% in MQL + CO2 machining process compared with dry cutting, MQL and CO2 cryogenic individually.Jayal et al.  studied u et al.  studied u et al.  compareda et al. ,25 propo3), and grinding peak temperature (123.8 °C) and exhibited better grinding performance than the others.In addition, a large number of experimental studies have been carried out on vegetable oil as a metalworking cutting fluid, and it is found that vegetable oils can reduce friction and improve tool life in metal processing compared to mineral oils ,27,28,29Moreover, current research shows cutting fluids with extreme pressure additives can effectively improve the lubricating adhesion of the cutting tool under high temperature, workpiece surface finish and tool life . CambileThe purpose of this paper is to investigate the influence of the novel water-based cutting fluid and the traditional cutting fluid on the machined surface quality and tool life during the milling process of 7050 aluminum alloy. Firstly, the physical and chemical properties of two cutting fluids were characterized, which is synthesized by addition of alkyl alcohol amide and chlorinated polyolefin. Then, the effects of cutting fluids on the machined surface quality and tool life were investigated, including cutting force, surface roughness, morphology and tool wear.The workpiece material used in the study is high-quality 7050 aluminum alloy that has been heat-treated , and the size of the workpiece is 80 mm × 76.5 mm × 40 mm. The chemical composition of 7050 aluminum alloy is shown in In this study, milling experiments were carried out under two different cutting fluid conditions. The traditional one is micro-emulsion semi-synthetic cutting fluid , which is a kind of water-soluble emulsified cutting fluid containing lubricating oil composition. The novel one is a type of water-based cutting fluid (QC-2803), which is developed by the Tianjin Equipment Research Institute of Tsinghua University. The components and functions of these two cutting fluids are shown in In order to investigate the cooling and lubricating properties, physical and chemical properties of these two cutting fluids were characterized, including viscosity, surface tension, cooling curve, pH and friction coefficient. The viscosity of cutting fluid was measured by rotary rheometer , surface tension was calculated by surface tensiometer , and the pH was tested by conductivity meter . Friction and wear tests were carried out to obtain the friction coefficients of two cutting fluids, which were measured by Universal Micro-Tribotester . The cooling performance of the cutting fluid is based on the method of measuring the heat transfer coefficient of quenching oil.x, y, z-axis travel of 600 × 400 × 300 mm, positioning accuracy of ±0.005 mm and motor power of 5.5 KW  was used, and the adopted cutting parameters are illustrated in The purpose of this study is to compare the effects of two cutting fluids on the machined surface quality and tool life during the milling process of 7050 aluminum alloy. The three-axis machining center with Spindle speed of 20,000 r/min, The workpiece was, firstly, milled to obtain a plane of 80 mm × 76.5 mm, and then milling experiments were performed with the adopted cutting parameters under two cutting fluid conditions. The total milling time for each cutting fluid was 200 min, and cutting force, surface quality as well as tool wear were measured and recorded at the designed time intervals. Kistler9257 dynamometer  was used to collect cutting force , and Keyence VK-100 laser 3D scanning microscope was used to measure the surface roughness and surface topography of the workpiece. CCD camera and JSM-7200F Thermal Field Emission Scanning Electron Microscopy (SEM) with Through-The-Lens System (TTLS) were used to record the tool wear morphology.Viscosity is a basic physical property that describes a fluid, which plays an important role in the lubricating and film formed penetrating ability of the cutting fluid, and it affects the thickness of the lubricating film formed between the tool and workpiece surface. The dynamic viscosity of two cutting fluids is shown in The surface tension of the liquid affects the permeability of the liquid, and it can be used to characterize the ability of the cutting fluid to spread out and form a lubricating film. The pH value reflects the corrosive properties of the cutting fluid. As shown in The cooling performance of the cutting fluid can effectively take away the cutting heat generated, which contributes to reducing the cutting temperature and improving the machined surface quality. The cooling curves of two cutting fluids are shown in The friction coefficient results of QC-2803 and CCF-10 are shown in The variation curve of surface roughness against cutting time is shown in The morphology results of the machined workpiece surface are shown in The original signals of cutting force were collected in three directions of X, Y, and Z, as shown in In order to study the effect of the novel water-based cutting fluid on tool life in the milling process of aluminum alloy, cutting fluid type was set as an independent variable while other milling parameters remain unchanged. The experimental results showed that the tool wear mode is nose-damage when the milling starts. QC-2803 cutting fluid can greatly reduce the degree of nose damage and prolong tool life. In the experiment, the GAOSUO 1003+ digital camera was used to examine the tool wear. The viscosity and friction coefficient results of two cutting fluids show that the lubricating performance of QC-2803 cutting fluid is superior to that of CCF-10, and the surface tension and cooling curve results illustrate that the cooling effect of QC-2803 cutting fluid is better. The big differences between two cutting fluids are lubrication, and the ability to form a lubricating film directly influence the machined surface quality and tool life.During the milling process, the tool and the workpiece keep in continuous contact, friction and frictional heat generated in the relative motion play important roles in the surface quality of workpiece . MoreoveAt the beginning of milling process, the cutting motion works from the fillet, so the cutting force is the largest (including impact) due to vibration when cutting into the workpiece, as shown in In terms of the physical and chemical properties of the cutting fluid, the viscosity of QC-2803 is 22.9% higher than that of CCF-10, the surface tension of QC-2803 is about 96.5% of CCF-10, the friction coefficient of QC-2803 increased by 20.0% compared with CCF-10. It is easier to form a lubricating film with a certain strength in case of QC-2803, and further reduce the friction between the tool and the workpiece.QC-2803 cutting fluid can form a stronger oil film and has better cooling performance compared with CCF-10 due to the extreme pressure additive components in water-based cutting fluid. The cutting force and its fluctuation are significantly decreased in both X and Y directions in case of QC-2803 cutting fluid. The cutting force is approximately reduced to 42.9% of CCF-10 cutting fluid.Higher surface quality is obtained in the milling process of aluminum alloy under the QC-2803 cutting fluid condition. The surface roughness is reduced by 20% on average. The maximum edge wear is 74.4% of that of CCF-10 cutting fluid, and it is assumed that the tool life under QC-2803 cutting fluid conditions is longer.In this paper, two cutting fluids were applied in the milling process of 7050 aluminum alloy. The cooling and lubricating properties of cutting fluids were characterized. The influence of cutting fluids on the machined surface quality and tool life were investigated. The main achievements are as follows:


Grallina cyanoleuca) vocal duets. Breeding pairs duet at varying distances from each other and to multiple neighbours. Coordinated duets are more effective territorial signals than uncoordinated duets, but it remains unclear whether listeners can discriminate the effects of quality and spatial arrangement. Our playback experiment showed that any deviation from perfect regularity of partners’ notes reduced duet efficacy, but that lack of coordination due to spatial separation (slower tempo and offset of notes) had a lower effect on efficacy than effects due to intrinsic quality (irregularity). Our results therefore provide experimental evidence that the temporal organisation of group vocalisations could signal coalition quality independently of spatial effects.Interactions among groups are often mediated through signals, including coordinated calls such as duets, and the degree of temporal coordination within a group can affect signal efficacy. However, in addition to intrinsic duet quality, the spatial arrangement of callers also affects the timing of calls. So, can listeners discriminate temporal effects caused by intrinsic duet quality compared to spatial arrangement? Such discrimination would allow assessment of quality of duets produced by a pair, as distinct from transient extrinsic spatial effects. To address this issue, we studied experimentally the influence of intrinsic duet quality and spatial arrangement on the efficacy of Australian magpie-lark ( Coordinated signalling can play a bonding role among related individuals or in mated pairs, such as in paired siamangs (Hylobates syndactylus)7, but it can also be strategically important during interactions with other groups9. As examples, sounds allow for a numerical assessment at a distance in lions (Panthera leo)10, spotted hyenas (Crocuta crocuta)11 and subdesert mesites (Monias benschi)12; and evaluation of the spatial distribution of callers in túngara frogs 13, black-capped chickadees (Poecile atricapillus)14, eastern towhees 15, Australian magpie-larks 17 and orcas (Orcinus orca)18. The precision of timing may also allow the quality of the group or pair be assessed, as shown for duetting birds20. We focus on duets involving breeding pairs, as providing the simplest way to explore the importance of timing in assessing the quality of cooperative displays.Cooperative vocal displays by pairs or groups of animals are often characterised by temporal coordination21. Consider an antiphonal duet, in which partners alternate notes within a duet. During production, duet tempo will decline as callers get further apart if each partner awaits the arrival of their partner's note before calling themselves22. Alternatively, tempo may be unaffected or less affected if partners use visual components of display to time contributions16. Duet reception is also affected by the relative distance to each caller because notes from the more distant caller will arrive after a delay, so the contributions of different callers are offset23. In extreme cases, when the difference in distance is large, the offset may cause notes to overlap. Information on spatial arrangement of callers is useful in indicating readiness for immediate, joint cooperation23. However, given that the spatial arrangement of callers and listeners is not an intrinsic property of duet quality, listeners may prioritise temporal features of duets that are under immediate control by callers, and so more likely related to coalition quality. Here we consider intrinsic duet “quality” to include both the skill of individuals, which can be related to their experience together19, and their motivation, as both of these properties of the pair are likely to affect territorial defence.A listener’s assessment of duet quality is complicated by the spatial arrangement of callers and the relative position of the listener. This is because the relatively slow speed of sound means that duet production is affected by the distance callers are apart, and duet reception depends on the distance of the listener from each callerCossypha heuglini), for example, sing several categories of duets. In one of them, the male’s singing is independent of the female’s response. Coordination is then relatively low and the female’s singing appears to be directed towards interaction with the mate, since pairs do not signal this way when interacting with others24. By contrast, when the initiator and the responder react to each other note-by-note, the quality of the duet will be the result of both partners’ quality. Robin chats call in note-by-note alternation in their interactions with other pairs24, suggesting that this type of mutual coordination does signal group cohesion. Apart from the influence on timing, the lack of regularity of partners may, in extreme cases, lead to overlapping of the partners’ notes. Where they are usually produced alternately, overlapping may therefore signal inexperienced partners and not just spatial separation19.The quality of cooperative signallers is likely to affect the precision of responses to their partner, independently of any spatial effects on tempo and offset. This is important, because listeners should be selected to discriminate signals of coalition quality from the temporary cues of spatial arrangement of callers, yet there has been no experimental discrimination of these possibilities. Nevertheless, this task is difficult as, even in the production phase, irregularities can arise in many ways Fig. , Table 119. Furthermore, the level of coordination increases with the pair’s tenure, so that coordination is likely to signal skill or motivation for defence19. However, in previous experimental work, coordinated and uncoordinated playbacks differed in multiple ways, so it was not possible to tell what features of temporal organisation affected response. In subsequent studies, birds responded less to offset duets than to regular ones, but the experiments were designed to examine audio-visual communication, so that the treatments also included robotic taxidermic models17. Here, we test experimentally the impact of temporal coordination of vocal duets related to both spatial separation and intrinsic duet quality. We distinguished six categories of temporal distribution of notes within a duet , and birds responded more to duets associated with spatial effects than to quality effects , but this difference was similar among treatments .As predicted, birds were most responsive to regular, fast duets, and least responsive to temporal variation associated with low duet quality rather than spatial separation. Overall, there was a strong effect of playback treatment on both measures of response  had less impact on response than the effects of intrinsic duet quality (irregularity). Our results therefore provide experimental evidence that duet timing could signal the skill or motivation of the coalition independently of spatial cues.17, there was a weakened response to duets with slow tempo or offset, which are both consequences spatial separation. The treatments in previous experiments, however, combined the vocal duet with visual display movements of taxidermic models. These visual signals influenced the reactions to songs yet, unlike acoustic signals, visual ones are not affected by temporal delays. Therefore, the results of those experiments could not isolate the impact on response of spatial effects on signal timing. By contrast, the current experiment isolated the acoustic component of the duet display, which is subject to spatial effects because of the slow speed of sound. We suggest that reduction in response to slow and offset duets is precisely because these features betray the physical separation of signallers, which indicates that the pair is not currently united. This type of tactical information can be important during territorial interactions as it allows for the right defensive strategy. As an example, wolves that live in larger packs respond intensely to vocalisations of strangers when together and weakly when dispersed. At the same time, the dispersal of the group usually occurs after the end of the common howling session25. These observations suggest that group members signal cohesion but conceal dispersion.Spatial effects on duet tempo and timing did affect responses to playbacks, potentially because the current spatial separation of callers is relevant to territorial defence. Consistent with our previous results16. Magpie-larks have several types of song notes within their repertoire, differing in length, and this choice alone can affect the duet tempo. However, partners may also choose a specific tempo for a given duet type based on shared experience and learning3. Second, tempo does not fall as rapidly with distance as expected from the speed of sound, probably because birds partly use visual cues to time responses to their partner’s songs16. In contrast to tempo, offset is unaffected by tempo and is an inevitable consequence of spatial separation when the listener is closer to one of the callers. Furthermore, unlike the change of tempo with partners’ separation, which occurs in both acoustic and visual components of the duet display, offset is a purely acoustic phenomenon. Therefore, the visual component is not relevant to interpret offset.Although tempo and offset are both outcomes of spatial separation, tempo had less effect than offset, suggesting that other factors are also important. We suggest that this is because tempo is a poorer cue of spatial separation, for two reasons. First, tempo is a less reliable indication of separation because partners can sing at different tempos for a given spatial separation19. These poorly coordinated duets also included overlapping of notes, and it is possible that overlapping is itself an additional cue of quality, independent of irregularity, but this is unknown19. Overlapping of notes may make the timing of notes difficult to assess, reducing the ability to gain information from temporal cues. Furthermore, overlapping might indicate conflict within the signalling pair. Many songbirds avoid acoustic interference by short-term adjustment of song timing27, which suggests that overlapping could be related to competition rather than cooperation. Consistent with this, duetting antbird females respond to unpaired females by overlapping the signals of their own mates, who in turn compensated by adjusting their signals to avoid interference28. Regardless of the specific cues used or presence of conflict, being able to assess intrinsic duet quality, as distinct from spatial effects, is likely to be of benefit when defending the territory, such as by prioritising defence against pairs that represent greater threats.As predicted, temporal cues of intrinsic duet quality had a greater effect on response to duets than cues of spatial separation. Birds reacted most strongly to duets that were fully regular and with a fast tempo, less to duets with slow tempo or offset, which indicate spatial separation, and least to irregular duets, which are likely to indicate less experienced pairs . Furthermore, the weakest reaction was caused by completely irregular duets. Such poorly coordinated duets are produced mainly by less experienced pairs19. A similar effect of coordination was found for duetting rufous-and-white wrens  that responded more intensely to coordinated than uncoordinated duets, but again specific cues were not resolved5.Many previous studies have pointed to the negative consequences of lack of coordination, but have not discriminated effects due to spatial separation compared to intrinsic effects of skill or motivation. An earlier experiment on magpie-larks found that coordinated duets elicit stronger responses than uncoordinated ones, but the uncoordinated treatment differed in a variety of temporal parameters, so it was unclear which specific features affected response29. Spatial effects are therefore a component of signalling for many species. In amphibians and insects that call in choruses, females tend to approach the leading sound30. This type of preference is straightforward when the leading call actually precedes others31, however, reverberations can distort this pattern and lead to perceptual fusion and moving towards phantom or reflected positions33. Because the calls of frogs and insects are pulsating in structure, precedence will inevitably depend on the receiver's position relative to the senders. However, it can also arise as a result of deliberate masking and anticipation of competitor's calls31. Such intentional interference will be effective, given that precedence works independently of the amplitude of the calls31, and thus of the distance cue, and seems to be the effect of perceptual bias30. However, there are no studies on precedence that would unambiguously separate the influence of interactions between calling males from their actual spatial distribution.Group signals such as vocal duets and choruses are very common in animals, and separation of senders is inherent in this form of signalling34. Chemical signals are subject to even greater spatial effects, although it is not at all certain whether timing has any significance in this form of communication, taking into account the characteristics of this medium. Chemical diffusion, which is the main mechanism of chemical propagation, is non-directional and slow because, instead of waves, it requires the movement of molecules that dilute rapidly in a medium that is also moving. As a result, all temporal patterns in chemical propagation are lost at a small distance from the source35, and little is known about the role of spatial effects in chemical communication, especially considering the vast spectrum of substances that may be involved in signalling. Spatial effects can also play a role in the assessment substrate-borne vibrational signals of invertebrates36. Because different parts of the plant have different and specific frequencies at which vibrational energy propagates particularly well, the type of substrate may have a potential influence on the distance estimation to the sender37. Overall, there are many opportunities to study the effects of spatial separation on communication.In addition to acoustic signals, spatial effects on assessment of signals arise in other modalities. Visual signals are independent of spatial effects entailing time delays, but spatial arrangement still plays a role in visual signalling and perception. For example, male bowerbirds create courts with grey and white objects that increase in size with the distance from the entrance to the bower. This gradient creates a forced visual perspective for the female, which can yield false perception of size and distance39. Pairs defend territories throughout the year40, and the sexes are easily distinguishable by plumage differences41. Males and females each produce solo songs, and can combine songs to form duets. Duets are typically antiphonal and can be initiated by either sex. Solo songs consist of a series of short notes , which are 300–600 ms long and given at a tempo of about 1 note/s. Individuals have a repertoire of about three to six different song types, each composed of a single, repeated note3. In duets, partners alternate their notes on average six or seven times. Each bird uses the same note type throughout a duet, but it is rare for pairs to sing a duet in which each bird uses the same note type42. The timing of partners’ notes is often precise, with perfect alternation and a regular tempo of about 1 note/bird per second. Pairs that have been together longer are more likely to produce more coordinated duets, which are more threatening territorial signals19. Furthermore, studies using taxidermic models have shown that vocalizations indicate the number of individuals and their spatial distribution43.We studied a population of magpie-larks in parks and suburbs of Canberra, Australia. Magpie-larks inhabit open woodland, and suburban parks and gardens, through most of Australia44, to test specifically for the effects of acoustic timing, independently of their interactions with visual cues and direct spatial effects. We broadcast six treatments, in randomised order, on 144 mated pairs of magpie-larks, with each treatment carried out on 24 pairs. The creation of treatments was similar; they differed only in the temporal distribution of male and female notes : male and female notes were alternated with perfect regularity of inter-note intervals, defined as the period from the start of one note to the start of the previous note by the other bird, and produced with even tempos of 1 note/s for each bird  received a treatment variant with a duet initiated by the closer bird and half by the further bird . From the perspective of the receiver, when the duet is offset the notes of the further sender are delayed in relation to the closer one. As a result, the inter-note intervals of one individual are long and of the other is short, so that a whole duet sounds as if the consecutive intervals were alternately longer and shorter. To isolate the effect of offset from the slower tempo of separated partners, we did not add delays between the notes of the partners. This timing corresponds to a situation in which partners respond to each other based on visual cuesSingle caller irregular: the contributions of one caller were played back with regular inter-note intervals, while the other bird’s notes were played back alternately with short and long intervals. This pattern cannot arise merely from spatial separation, and therefore is related to intrinsic duet quality. In this treatment, half of birds 12) received a duet in which the duet initiator called with regular inter-note intervals and half in which the responder called regularly  received a duet without lag, that is when the responder was the copier, and half with the lag, that is when the initiator was the copier . In each treatment, half of the duets started with each sex and half started with each kind of note.Playbacks originated from high-quality recordings of duets from 144 local pairs, so that each pair received a unique exemplar from unfamiliar birds (> 2 km). Recordings were from an Olympus LS-11 and Sennheiser ME66 microphone, sampling wave files at 48 kHz and 16 bits. The files were high-pass filtered individually to remove sound below the notes, based on visual inspection, and the male and female tracks were composed using Avisoft-SASLab Pro software . Every duet playback contained eight notes that were formed by pasting male and female notes into a stereo wave file in alternation, and lasted about 4 s for control playbacks to 4.5 s for slow tempo playbacks, which is natural timing Fig. . To furt42, so a one-minute pause is therefore common. Each pair of birds received only one playback. Playbacks were broadcast from a JBL Xtreme amplified stereo loudspeaker . Songs were broadcast at natural amplitudes of 66–70 dB SPL at 10 m, measured by a RadioShack Sound Level Meter see also45.Playbacks were carried out in October and November 2019, between 0630 and 1115 h on days without rain or strong wind. Playbacks were initiated only if partners were together and within 25 m of the speaker, and if they had not engaged in any interaction with neighbours or sung during the minute before each treatment. In our earlier study, the birds sang only once on average for five minutes before playback45. Therefore, we expect males to initiate more songs than females over all treatments42. Given the low background rate of song42 (above), song rate in the 1 min sample period is a good measure of the reaction to playback.We measured the response to playback in the 1 min period starting from the onset of the playback. We counted the number of songs initiated by males and females, including solos and duets initiated by each individual, and the number of duets produced by a pair. Solo songs and duet initiations represent individual-based behaviours that are a proxy of territorial response of individuals, whereas duets require a response to the partner’s song, and thus they represent a proxy of cooperative territorial defence. Song rate, particularly of males, is the most sensitive measure of response to territorial threat in magpie-larks46. Unlike mixed models, which estimate subject-specific effects (random effects), GENLIN and GEE estimate population-averaged effects and are therefore appropriate for ecology or social sciences. We carried out separate analyses for each response variable. To compare the number of songs initiated by paired males and females we used GEE, which is appropriate for paired measurements, whereas to compare the number of duets by pairs we used GENLIN. Within GENLIN and GEE, we used an a priori contrast of the responses to “spatial effects” and “quality effects” 48. The analyses used SPSS 28 software. All P-values were two-tailed, and means ± SE are given.To compare the effects of experimental treatments on responses of birds we used generalized linear models (GENLIN) and their extension generalized estimating equations (GEE). Both procedures are suitable for non-normally distributed data and both allow the use of heteroskedasticity-consistent standard errorsts” Fig.  and postAll experimental protocols were approved by the Australian National University Ethics Committee (A2018/10), Australian Bird and Bat Banding Scheme, and Environment ACT. The use of the animals adhered to guidelines for animal research in Australia .Supplementary Information 1.Supplementary Table 1.


The study demonstrated that both tris complexes [LnQcy3(H2O)(EtOH)] and tetrakis-acids [H3O][LnQcy4] can be synthesized by varying the synthetic conditions. The photochemical properties of the complexes were investigated experimentally and theoretically using various molecular spectroscopy techniques and Judd–Ofelt theory. The objective was to quantitatively and qualitatively disclose the influence of complex stoichiometry on its luminescence properties. The study showed that the addition of an extra ligand molecule (in the tetrakis species) increased molar extinction by up to 2 times, affected the shape of photoluminescence spectra, especially of the Pr3+ complex, and increased the quantum yield of the Sm3+ complex by up to 2 times. The results obtained from this study provide insights into the luminescent properties of lanthanide coordination compounds, which are crucial for the design and development of novel photonic materials with tailored photophysical properties.Six new complexes of the ligand HQ Nowadays, there is a high demand for creating new highly efficient sources of emission at the near-infrared (NIR) ,2 or bot3+ ions  [3(L)], binuclear [Ln2Q6] [4] tetrakis-acid anions, where M is an hydroxonium  ,29,30,31 [Ln2Q6] ,33, obtaroxonium ,34,35, aroxonium ,36 or siroxonium . Easily roxonium . Unforturoxonium ,38,39. Croxonium . Secondlroxonium ,42,43.3+, Pr3+ and Nd3+ ions with methanoncyclohexyl(5-hydroxy-3-methyl-1-phenyl-1H-pyrazo-4-yl)methanon were synthesized 3(H2O)(EtOH)]∙(EtOH) and [H3O][Sm(Qcy)4].As all lanthanide complexes are isostructural , structu8} which is best described as a square antiprism. Additionally, the structure contains one solvated molecule of ethanol, which is involved in hydrogen bonding with the water molecule (O1W…O1S distance is 2.70 Å). Upon further analysis of the crystal packing, the presence of intermolecular hydrogen bonds between the water molecule and pyrazole fragment of the adjacent molecule of the complex (O1W…N2 distance is 2.83 Å) was revealed, leading to the formation of hydrogen-bonded centrosymmetric dimers 4]−, while the hydronium cation (H3O)+ is present as a counterion. The {SmO8} coordination polyhedron is best described as a square antiprism. Additionally, the complex lies on a two-fold rotation axis, and only half of the molecule lies in the asymmetric unit of the crystal structure. Additional proof of the electric negativity of the complex can be found from the bond length analysis of the diketone fragment 3(H2O)(EtOH)]∙(EtOH), [H3O][Pr(Qcy)4], [Nd(Qcy)3(H2O)(EtOH)]∙(EtOH), [H3O][Nd(Qcy)4], [Sm(Qcy)3(H2O)(EtOH)]∙(EtOH) and [H3O][Sm(Qcy)4] dissolved in MeCN, are shown in 1 energy values for all the compounds are similar and oscillate about 28,500 cm−1. The increase in molar extinction is explained by an increase in the oscillator strength value of S0 ⟶ S1 transition due to the influence of heavy ions on ligand wave functions for the ground and excited states.Optical absorption spectra, obtained for HL and complexes [Pr(Qcy)3(H2O)(EtOH)]∙(EtOH) and [H3O][Nd(Qcy)4] complexes, 1.4 for [Sm(Qcy)3(H2O)(EtOH)]∙(EtOH) and [H3O][Sm(Qcy)4], and by almost two for [Pr(Qcy)3(H2O)(EtOH)]∙(EtOH) and [H3O][Pr(Qcy)4] complexes.Additionally, as the spectra obtained for tris and tetrakis complexes are qualitatively similar, it is clear that the optical absorption of complexes is related to ligand absorption. Notably, adding an additional organic ligand molecule leads to an increase in molar extinction by a factor of two for ∙(EtOH) and [H3O][Sm(Qcy)4] complexes in the visible and near-IR regions are shown in 3+ ion: 3O][Sm(Qcy)4] reveal more sub-bands than the spectra of [Sm(Qcy)3(H2O)(EtOH)]∙(EtOH), which may indicate that the tetrakis complex has lower coordination polyhedron symmetry in comparison with the tris complex ∙(EtOH) and [H3O][Pr(Qcy)4] complexes are shown in 3+ ion detected in the visible region of the luminescence spectra of complexes, as well as wide ligand luminescence bands in the blue-green region of the spectrum. The observed narrow emission bands centered at 485 nm, 527 nm, 594 nm, 606 nm, 645 nm, 684 nm, 706 nm and 628 nm originate from 3+ ion, respectively. The presence of highly intensive ligand fluorescence in the tris complex spectrum indicates an incomplete transfer of energy to the excited states of the ion. Notably, there is a decrease in the relative intensity of the luminescence of the ligand for the tetrakis complex in comparison with the tris complex.The PL spectra of the ∙(EtOH) and [H3O][Nd(Qcy)4] complexes are shown in 3+ ions are observed in the spectra:The photoluminescence spectra of [Nd3(H2O)(EtOH)]∙(EtOH) complex has more intensive bands related to excitation through the ion than [H3O][Nd(Qcy)4], while for Pr3+ ion complexes, tetrakis one has more intensive bands related to excitation through the ion.The photoluminescence excitation spectra were obtained for all the investigated complexes with the registration wavelength of 1064 nm for Ndwise See . The most  intensity parameters as well as the trad radiative lifetimes of the emission states of the ions are presented in 3+ and Sm3+ complexes was the same as in [Sm(Qcy)4] is 6 times higher than that for [Sm(Qcy)3(EtOH)]. Increasing of the radiative lifetime generally and mostly resulted from the stronger mixing of the 4f-states with the opposite parity states from configurations with higher energies [2 is strongly enhanced by covalent bonding and depends on the degree of symmetry of the ligand environment. Relative to the analysis of the Stark splitting and X-ray analysis for these complexes (see one for the tris complex here [cy)3(H2O)(EtOH)]∙(EtOH) indicating the so-called “nephelauxetic effect” [Pr(Qcy)4] complex.As for the praseodymium complexes, we conclude that the radiative lifetime t2 parameters. Thus, the symmetry state for both complexes is the same or very close. We suppose that this behavior results from changes in the delocalization of the outer d-orbitals of ions caused by the ligand field (this is the nephelauxetic effect).The analysis of the neodymium complexes reveals a 22% decrease in lifetime from 255 to 198 µs for tetraxis complexes, and no changes in Ω3+ complex had a longer lifetime compared to the tris Sm3+ complex. In particular, characteristic lifetime measured at the registration wavelength of 650 nm for [H3O][Sm(Qcy)4] was 55 μs, which is four times greater than the lifetime of 13 μs recorded for [Sm(Qcy)3(H2O)(EtOH)]∙(EtOH). Similarly, an increase in the luminescence lifetime was observed in the NIR region with the registration at 953 nm 3(H2O)(EtOH)]∙(EtOH) and [H3O][Pr(Qcy)4] complexes are shown in 3+ complexes and can be fitted by a multiexponential law:iτ and iA are lifetimes and corresponding amplitudes, respectively. The measured luminescence decay is determined byirfτ = 0.5 ns for the measurements in the NIR region of the spectrum and an exponential function with the characteristic time irfτ =1 ns 3(H2O)(EtOH)]∙(EtOH) and 1693 ns for [H3O][Pr(Qcy)4], and is related to ligand phosphorescence, which was observed in PL spectra (See The Pr(τ3) See . The lonctra See . We coulcy)3(H2O)(EtOH)]∙(EtOH) with registration at the visible spectral region are several times higher than the lifetimes at the NIR spectral region. This phenomenon can be explained by the fact that the radiative transition 3O][Pr(Qcy)4] complex had a monoexponential decay at the NIR spectral region, and the long-term decay component vanished, in contrast to [Pr(Qcy)3(H2O)(EtOH)]∙(EtOH) complex, which remained biexponential.Specifically, the lifetimes obtained for [Pr(Qcy)3(H2O)(EtOH)]∙(EtOH) and [H3O][Nd(Qcy)4] complexes, with the registration wavelength of 1056 nm, are shown in Photoluminescence decays for [Nd3(H2O)(EtOH)]∙(EtOH) complex has Φ = 0.5% in the NIR spectral area and Φ = 1.3% in the visible spectral area, while [H3O][Sm(Qcy)4] complex has Φ = 0.4% and Φ = 2.0% in the NIR and visible regions, respectively. Therefore, adding the fourth ligand molecule to a compound leads to a significant increase in Φ for visible emissions, while there is no effect in the NIR region.Photoluminescence quantum yield (Φ) values were measured for all the compounds under optical excitation at 365 nm. As seen from 4G5/2 → 6H9/2 transition of the Sm3+ ion, which is the most intensive emission band, is an electric dipole transition, while the 4G5/2 → 6H5/2 transition is a magnetic dipole transition. On that basis, ligand environment polarizability of Sm3+ ion tris and tetrakis complexes was estimated as the difference between the integrated magnetic dipole and electro dipole transitions. As we observed a bigger value for the tetrakis complex (10.3 for tetrakis against 7.8 for tris), we conclude that it is more polarized, which can explain the increase in the quantum yield in the visible region for the tetrakis complex in comparison with the tris one.The cy)3(H2O)(EtOH)]∙(EtOH)  was carried out on a Bruker D8 Venture diffractometer , and SCXRD analysis of (H3O)+[Ln(Qcy)4]−  was carried out on a Bruker D8 Quest diffractometer . The structures were solved with direct methods and refined using the least-squares method in the full-matrix anisotropic approximation on F2. All hydrogen atoms were located in calculated positions and refined within a riding model. All calculations were performed using the SHELXTL  were prepared according to the previously reported procedure [The tetrakis complexes Hrocedure . For IR 3O[Pr(Qcy)4], 1. Green plates, 75%. Anal. Calc. for C68H79N8O9Pr: C, 63.15; H, 6.16; N, 8.65; Pr, 10.89%. Found: C, 62.1; H, 6.4; N, 8.6; Pr, 10.5. IR (cm−1): 3510 VW (ν O–HH3O+), 2927 M, 2851 W (ν C-HCyclohexyl), 1672 W (δ O–HH3O+), 1614 VS (ν C=ODiketone), 1594 S, 1581 M, 1497 VS (ν C–C), 1484 S, 1461 M, 1437 S, 1410 M, 1399 M, 1369 M, 1324 W, 1149 VW, 1124 VW, 1079 M, 1029 W, 1009 W, 999 W, 978 M, 921 W, 906 W, 809 W.H3O[Nd(Qcy)4], 1. Pale violet plates, 74%. Anal. Calc. for C68H79N8NdO9: C, 62.99; H, 6.14; N, 8.64; Nd, 11.12%. Found: C, 63.1; H, 6.7; N, 8.5; Nd, 10.5. IR (cm−1): 3604 VW (ν O–HH3O+), 2926 S, 2851 S (ν C-HCyclohexyl), 1672 S (δ O–HH3O+), 1615 VS (ν C=ODiketone), 1594 S, 1581 S, 1498 VS (ν C–C), 1484 VS, 1461 S, 1437 VS, 1410 S, 1399 S, 1368 VS, 1324 S, 1234 M, 1149 M, 1079 S, 1029 M, 1009 M, 999 M, 978 S, 920 W, 904 M, 809 S, 691 S.H3O[Sm(Qcy)4], 1. Pale yellow plates, 78%. Anal. Calc. for C68H79N8O9Sm: C, 62.69; H, 6.11; N, 8.60; Sm, 11.54%. Found: C, 62.0; H, 6.7; N, 8.5; Sm, 11.9. IR (cm−1): 3508 VW (ν O–HH3O+), 2927 M, 2852 M (ν C-HCyclohexyl), 1674 M (δ O–HH3O+), 1616 VS (ν C=ODiketone), 1594 S, 1582 S, 1498 VS (ν C–C), 1486 S, 1461 S, 1411 M, 1399 M, 1370 S, 1324 W, 1234 W, 1150 W, 1125 W, 1080 S, 1029 M, 1009 W, 999 W, 978 M, 921 W, 905 W, 904 W, 810 M.Tris complexes [Ln(Qcy)3(H2O)(EtOH)]∙(EtOH). were synthesized using a modified method [Hcy)3(H2O)(EtOH)]∙(EtOH) Green needles, 66%. Anal. Calc. for C55H71N6O9Pr: C, 59.99; H, 6.50; N, 7.61; Pr, 12.80%. Found: C, 60.1; H, 6.5; N, 7.6; Pr, 12.8. IR (cm−1): 3590 VW (ν O–H H2O), 2929 M, 2852 W (ν C-HCyclohexyl), 1646 M (δ O–H H2O), 1614 VS (ν C=ODiketone), 1593 S, 1582 S, 1531 M, 1499 S (ν C–C), 1460 S, 1453 M, 1437 S, 1398 M, 1371 M, 1325 W, 1234 W, 1200 VW, 1176 VW, 1156 VW, 1142 VW, 1129 VW, 1079 M, 1027 W, 1010 W, 1000 W, 979 M, 905 VW, 756 M.[Pr(Qcy)3(H2O)(EtOH)]∙(EtOH) Pale violet needles, 66%. Anal. Calc. for C55H71N6O9Nd: C, 59.81; H, 6.48; N, 7.61; Nd, 13.06%. Found: C, 60.2; H, 6.5; N, 7.6; Nd, 13.1. IR (cm−1): 3632 VW (ν O–H H2O), 2930 M, 2852 W (ν C-HCyclohexyl), 1645 M (δ O–H H2O), 1613 VS (ν C=ODiketone), 1594 S, 1582 S, 1532 M, 1499 S (ν C–C), 1461 S, 1453 M, 1438 S, 1399 M, 1374 M, 1325 W, 1235 W, 1201 VW, 1176 VW, 1157 VW, 1142 VW, 1129 VW, 1079 M, 1028 W, 1010 W, 1000 W, 979 M, 756 M.[Nd(Qcy)3(H2O)(EtOH)]∙(EtOH) Pale yellow needles, 62%. Anal. Calc. for C55H71N6O9Sm: C, 59.48; H, 6.44; N, 7.57; Sm, 13.54%. Found: C, 59.7; H, 6.5; N, 7.6; Sm, 13.7. IR (cm−1): 3627 VW (ν O–HH3O+), 2930 M, 2852 W (ν C-HCyclohexyl), 1672 VW (δ O–HH3O+), 1614 VS (ν C=ODiketone), 1594 S, 1582 M, 1532 M, 1501 VS (ν C–C), 1487 S, 1461 M, 1451 S, 1437 S, 1398 M, 1373 M, 1324 W, 1234 W, 1176 W, 1157 W, 1129 W, 1079 M, 1027 W, 1010 W, 1000 W, 979 M, 921 W, 755 W.[Sm, respectively, we observed a huge increase in quantum yield for the Sm3+ tetrakis complex in the visible region in comparison with the tris complex (from 1.3% to 2.0%), although their quantum yield values in NIR region are practically equal (0.4–0.5%). We consider that the luminescence quantum yield increase in the Sm3+ ion complexes is related not only to the substitution of water molecules by a ligand molecule, but also to the polyhedron symmetry change.While NdThe findings of this study may have significant implications in optoelectronics, telecommunication, and bioimaging, where the utilization of luminescence in the NIR region of the spectrum can lead to advancements in sensing, imaging, and other cutting-edge technologies.


Background and objectivesA fluid responder is a patient who can increase his stroke volume/ cardiac output by more than 10%-15% after a fluid bolus. Left ventricular outflow tract (LVOT) velocity time integral (VTI) variability is widely used as an adynamic parameter of fluid responsiveness, but a transthoracic echo view of LVOT VTI is often time-consuming and, at times, difficult to achieve. So, in the quest for another parameter that might equally be a good surrogate marker of stroke volume variation, carotid peak systolic velocity (CPSV) variation has been studied. The objective was to assess CPSV variation in patients who are already fluid responders.MethodsThe sample size was calculated considering a minimum correlation coefficient of 0.5. Adult patients in whom the physician wanted to give a fluid bolus and whose average LVOT VTI was more than 15% over 3 respiratory cycles were included in the study. Demographic variables, along with hemodynamic parameters such as heart rate, blood pressure, the need for vasopressors, mode of breathing , and CPSV variation,were noted and averaged over three respiratory cycles. Fluid bolus  6 ml/kg bolus over 10-15 minutes. Post-fluid hemodynamic variables, along with averaged LVOT VTI over three respiratory cycles and averaged CPSV variation over three respiratory cycles, are noted.ResultsThirty adult patients were evaluated in the study. In spontaneously breathing patients (n=12), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight was 14.1 ± 3.4 and 5.4 ± 2.6, respectively (p < 0.05). In mechanically ventilated patients (n=18), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight fluid was 15 ± 5.3 and 6.5 ± 3.1, respectively (p <0.005). Overall, there was a statistically significant positive correlation between LVOT VTI variation and CPSV variation before fluid therapy  and a statistically significant moderate positive correlation post-fluid therapy .ConclusionWe found a significant decrease in CPSV variation post-fluid administration in patients who are fluid responders, which mimics a decrease in stroke volume variation after fluid administration in patients who are fluid responsive. Fluid therapy is one of the key components of hemodynamic resuscitation. However, not all patients respond to fluid administration, and a positive balance is associated with a poor outcome .According to the Frank-Starling principle, increasing preload increases the left ventricular (LV) stroke volume when the ventricle is functioning on the steep part of the curve. However, when the ventricle is functioning on the flat portion of the curve, fluid boluses will fail to result in a significant hemodynamic improvement. However, this will increase cardiac filling pressures and eventually cause fluid overload. A fluid responder is a patient who can increase his stroke volume/ cardiac output by more than 10%-15% after a fluid bolus.Both static and dynamic parameters are utilized for the prediction of fluid responsiveness. The commonly used static indices are the central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP), which use markers of right and left cardiac ventricular preload, respectively. Other static markers of cardiac preload are the global end-diastolic volume and the left end-diastolic area/volume, or aortic blood flow, measured by transpulmonary thermodilution, echocardiography, and esophageal Doppler, respectively. However, it has been well-evidenced that dynamic indices are more reliable in predicting fluid responsiveness than static indices ,3. This Mechanical ventilation induces cyclic changes in left ventricular (LV) stroke volume, which is mainly related to the expiratory decrease in LV preload due to the inspiratory decrease in right ventricular (RV) filling and ejection . This reDynamic indices of stroke volume variation (SVV) or pulse wave variation (PVV) derived from the analysis of the arterial pressure waveforms are determined by cardiac output monitoring . Among tThe most widely accepted method for CO measurement using echocardiography is the measure of Velocity time integral (VTI), which is the stroke distance of blood during systole (cm) combined with LVOT cross-sectional area (cm2) . IllustrHowever, in a study, up to 40% of the patient population had technical difficulty obtaining echocardiographic apical views , and theThis observational study was conducted at the Gastro and Liver Transplant Intensive Care Unit, Medanta-The Medicity, Gurugram, India, from January 2020 to January 2021.Sample sizeThe objective of the study is to assess the variability of carotid peak systolic velocity in patients in shock who are fluid responders. Parameter of interest: Trend and the interrelationship between LVOT VTI variability and Carotid peak systolic velocity (CPSV) variability. For the calculation of sample size, the minimum value of the correlation coefficient is assumed to be 0.50 for clinical significance. With this, the minimum sample size works out to 30.Study populationThe study included Ages > 18 years when the physician wants to give fluid boluses in the presence of any of the below: systolic blood pressure < 90 mm Hg (or there is a drop of >40 mm Hg in a hypertensive patient), with vasopressor support, heart rate > 100/minute and urine output <0.5 ml/kg/hour, and left ventricular outflow tract velocity time integral variability > 15%. The study excluded Pregnancy, known chronic kidney disease on maintenance hemodialysis, aortic valvular abnormalities, and common carotid artery stenosis.Study objectiveTo assess the variability of carotid peak systolic velocity in patients who are fluid responders when compared to LVOT VTI.Data collectionThe cases were chosen from the patients fulfilling the inclusion and exclusion criteria in the ICU. The basic parameters of age, height, weight, heart rate, blood pressure, and if there were any requirements for vasopressors, along with dose, were noted. Both spontaneously ventilated and mechanically ventilated patients were included in the study. Then the echocardiographic parameter LVOT VTI variability averaged over three respiratory cycles was measured. The patients with average LVOT VTI variability >15%, as a part of the inclusion criteria, are taken as the cases, and then CPSV variation averaged over three respiratory cycles is measured and noted , with the sample volume placed within the LVOT, approximately at 1 cm distance to the aortic valve. The maximum and minimum VTI need to be recorded to calculate VTI variability, which is calculated as follows: [(VTImax-VTImin)/(VTImax +VTImin/2)]*100%. The average LVOT VTI taken over three respiratory cycles was calculated and noted. And using the linear probe at 6-13 MHz, a longitudinal view of the common carotid artery was procured, and pulsed wave Doppler analysis at 2 cm from the bifurcation was performed . The samStatistical analysisIBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp. analyzed the MS Excel  data when it was loaded. Quantitative  data were given as mean and standard deviation, whereas qualitative  data were provided as frequency and percentage. The student t-test was used to compare the two groups' mean values, while the chi-square test analyzed their frequency differences. If p < 0.05, it was statistically significant.Thirty adult patients were included in the study. The maximum number of study subjects (30%) lies in the age group of 51 to 60 years. This was followed by age groups 31 to 40 years (26.7%), 41 to 50 years (16.7%), and 61 to 70 years (13.3%), respectively. The mean age of the study subjects was 49.6 years. The proportion of male and female study subjects was equal (50%). There were 63.33% of subjects who required vasopressors during treatment. We observed that 60% of patients were on mechanical ventilation, while the remaining 40% had spontaneous breathing (Table The mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significantly lower before fluid therapy as compared to after fluid therapy in patients with spontaneous breathing . However, in patients on mechanical ventilation, a statistically significant difference was not observed for mean systolic blood pressure p = 0.255). Overall, SBP and DBP were significantly higher after fluid resuscitation   in patients who are fluid responders, which means the patients were considered fluid responsive by the need to administer fluid as defined by the clinical parameters mentioned in the inclusion criteria and their LVOT VTI > 15%. Pre-fluid CPSV variation and post-fluid CPSV variation were studied, and it was found that CPSV variation decreased after fluid therapy in patients with spontaneous ventilation, mechanical ventilation, and overall, which was statistically significant. It was also found that pre-fluid CPSV correlated with pre-fluid LVOT VTI, and post-fluid CPSV correlated with post-fluid LVOT VTI in patients with spontaneous breathing, mechanically ventilated, and overall.In our study, out of 30 patients, 12 (40%) were on spontaneous ventilation, and 18 (60%) were on mechanical ventilation. The study by Y. Song et al.  enrolledIn our study in spontaneously breathing patients (n=12), the average CPSV variation expressed as mean (standard deviation) before fluid was 14.1 ± 3.4 and 5.4 ± 2.6 post fluid administration of 6ml/kg of ideal body weight, the average CPSV variation was less statistically significant after fluid therapy as compared to before fluid with p-value < 0.001.In mechanically ventilated patients (n=18), average CPSV variation expressed as mean (standard deviation) before fluid was 15 ± 5.3 and 6.5 ± 3.1 post fluid administration of 6ml/kg of ideal body weight. The average CPSV variation was less statistically significant after fluid therapy as compared to before fluid, with a p-value < 0.001.Overall (n=30), the average CPSV variation expressed as mean standard deviation before fluid was 14.9 ± 4.6 and 6.1 ± 2.9 post-fluid administration with 6ml/kg of ideal body weight. The average CPSV variation was less statistically significant after fluid therapy as compared to before fluid, with a p-value of 0.0001 .In Y Song et al.,  carotid Kim et al.  found thThe correlation in this study between average LVOT VTI variation and CPSV variation has been evaluated. In spontaneously breathing patients, there was a statistically significant positive correlation (correlation coefficient = 0.66) before and after fluid therapy (correlation coefficient = 0.58). In mechanically ventilated patients before fluid therapy, there was a significant positive correlation (correlation coefficient = 0.54) between LVOT VTI variation and CPSV variation. Whereas post-fluid therapy, there was a weak positive correlation (correlation coefficient = 0.22) that was not statistically significant. Overall, there was a statistically significant positive correlation between LVOT VTI variation and CPSV variation before fluid therapy (correlation coefficient 0.56) and a statistically significant moderate positive correlation post-fluid therapy .The limitations of the study are that it was conducted at a single center; thus, findings need to be evaluated on a larger scale with multi-centric involvement. There is no previous study with a head-to-head comparison of CPSV variation and LVOT VTI variation. So, more studies are needed. There may also be the possibility of operator bias in measuring the echocardiographic parameters.The study found a significant decrease in carotid peak systolic variation post-fluid administration in patients who are fluid responders, which mimics a decrease in stroke volume variation after fluid administration in patients who are fluid responsive. Second, we found a correlation between CPSV variation and LVOT VTI variability, so we ought to extrapolate that CPSV variation can be used in place of LVOT VTI as a surrogate marker of stroke volume variation in assessing fluid responsiveness.


Background: Surgical interventions can cause severe fluid imbalances in patients undergoing cardiac surgery, affecting length of hospital stay and survival. Therefore, appropriate management of daily fluid goals is a key element of postoperative intensive care in these patients. Because fluid balance is influenced by a complex interplay of patient-, surgery- and intensive care unit (ICU)-specific factors, fluid prediction is difficult and often inaccurate.Methods: A novel system theory based digital model for cumulative fluid balance (CFB) prediction is presented using recorded patient fluid data as the sole parameter source by applying the concept of a transfer function. Using a retrospective dataset of n = 618 cardiac intensive care patients, patient-individual models were created and evaluated. RMSE analyses and error calculations were performed for reasonable combinations of model estimation periods and clinically relevant prediction horizons for CFB.Results: Our models have shown that a clinically relevant time horizon for CFB prediction with the combination of 48 h estimation time and 8–16 h prediction time achieves high accuracy. With an 8-h prediction time, nearly 50% of CFB predictions are within ±0.5 L, and 77% are still within the clinically acceptable range of ±1.0 L.Conclusion: Our study has provided a promising proof of principle and may form the basis for further efforts in the development of computational models for fluid prediction that do not require large datasets for training and validation, as is the case with machine learning or AI-based models. The adaptive transfer function approach allows estimation of CFB course on a dynamically changing patient fluid balance system by simulating the response to the current fluid management regime, providing a useful digital tool for clinicians in daily intensive care. In this regard, monitoring of vital signals and periodic assessment of fluid status are crucial. In daily clinical practice, the amount of body fluids gained or lost is usually estimated by calculating the external daily fluid balance . This rePossible CFB courses during a patient’s stay in the ICU have been described previously for critically ill, hyperhydrated patients  and can Based on the calculations for the daily fluid balance, individual goals are usually set for the patient to achieve optimal fluid management during the continued stay in the ICU. However, these goals may change due to alterations in the patient’s health status and the resulting adjustments to ongoing therapy. Therefore, setting adequate and achievable fluid balance goals requires profound and experienced knowledge. In addition to an intake-output-calculation, both currently applied therapies and planned interventions must be considered to estimate a specific fluid balance goal. Therefore, assessing and predicting the fluid balance can be challenging.Recent approaches to predict various physiological parameters using artificial intelligence , deep orIn this work, we present a first-of-its-kind digital model for predicting the patient-specific CFB trend over clinically relevant therapeutic timespans based on single patient CFI and CFB time series data. The algorithm should not only serve to improve the adjustment or optimization of therapies after cardiac surgery, but also to reduce the workload in intensive care units, as estimating the current CFB course is very time-consuming. The control theory model is intended to provide a basis for a more generally applicable algorithm.n = 2061 adult patients collected between 2011 and 2017 was used for sample selection. All patients underwent elective cardiac surgery for coronary artery bypass grafting and/or surgical valve replacement with subsequent admission to the cardio-thoracic intensive care unit at the Medical University of Graz, Austria. The study was approved by the Ethics Committee of Medical University of Graz in accordance with the Declaration of Helsinki (vote EK 30-076 ex17/18).A retrospective data set with a total of n = 926 patients were excluded because length of stay was less than 4 days and hemodynamic stabilization after surgery takes approximately 3 days , which is often used to describe the behavior of a physical or biological system. The TF allows the analysis of the dynamic properties of a system that models the systems output for each possible input function.n = 2. The general mathematical model of the system within the Z-domain is given by Eq. In the discrete-time domain, the TF can be determined using a discrete-time input time series U[k] and the corresponding output time series Y[k]. The Z-transforms of both signals (U[z] and Y[z]) are related to give the TF of the patient, P[z]. Following the control system theory, the transfer function should be chosen to correspond to the lowest-order differential equation to describe the behavior of a system. Basically, from a physiological point of view, oscillation and instability of the response to a fluid input is possible, resulting in the model to be at least a second order system. However, higher order systems led to a worse prediction in general. Possible reasons could be overfitting or the low variability of the input data, which makes an identification of a system depending on multiple parameters more difficult. Since it is not possible to increase the variability of the input data artificially, the transfer function with the empirically determined best result in prediction was selected. The model can basically be compared to a physical two tank water level system. The exponent n see Eq.  that detThe basic idea of CFB prediction using a system theory based modeling approach is shown in 0.For model implementation and prediction MATLAB (version 9.9 - R2020b Update 1 on Windows 10) and the system identification library (version 9.13) were used. The “iddata” function defines the transposed CFI and CFB as a system object. The number of poles of the TF model P[z] was set to 2, the number of zeros to 1, the sampling time was set to 60 s. By entering the “iddata” object and selected parameters into the “tfest” function, a TF object is created by non-linear least-squares search based updates to minimize a weighted prediction error norm. As the CFB is directly calculated from the CFI and CFL there is no delay from input to output assumed and therefore feedthrough must be activated by setting the “Feedthrough” parameter of “tfest” true. This object, along with the modeled and extrapolated input function, was used to simulate and predict the CFB trajectories. The resulting estimated TF with the previously described defaults can be seen in following Eq. Fluid data was imported from an SQL data base and included intakes  and losses  with their corresponding time points. The cumulative time series data were interpolated individually dependent on the specific type of administration or type of fluid loss using the “interp1” function for the entire length of stay at a sampling rate of one data point per minute. Interpolation was performed by inserting the last available value that followed the cumulative shape of the fluid data.Gravity infusions that did not have a documented ending timestamp were assumed by clinicians with a flow rate of about 16 mL per minute until the total administered volume was reached. Short infusions and drinking were included as bolus. Insensible losses such as estimating the volume lost by sweating were not considered in the data. Urine data was linearly interpolated to the next available documented entry with the simplified assumption that the bladder has filled evenly in a linear fashion during this time.The resulting individual CFI and CFL time series were subtracted to calculate the corresponding CFB to identify the TF. The described procedure for preprocessing the input and output data can be seen in detail in the flow chart in estimation time) and the last 24 h of each window used for prediction (prediction time). The sliding window was incrementally shifted by 2 h. Since fluid balance is constantly changing due to dynamically changing patient characteristics, the TF has to be periodically recalculated. A sliding window approach was chosen for TF estimation for (i) computational reasons and (ii) clinical considerations, because patients may become unstable again, which affects subsequent estimates. The length of the sliding window was set at 48, 72, 96, 120 and 144 h, with the first 24, 48, 72, 96 and 120 h used for TF estimation  within RStudio . The simulated (predicted) CFB course was compared with the real CFB within the maximal prediction period of 24 h. The root mean squared error (RMSE) of the last 30 min between both curves was calculated to determine the change of prediction error over time for the selected prediction times of 8, 12, 16, 20 and 24 h. This results in different prediction error combinations for model estimation (24–120 h) and model prediction (8–24 h) for a patient. Depending on the length of stay of each patient, not all combinations were available for all patients  is provided to the model. As can be seen in The model presented only estimates the behavior of the entire patient system by analyzing fluid intakes and losses and does not simulate a mechanistic fluid compartment system. Distributions of the fluids in the compartments and changes over time are therefore not included. Increased fluid retention due to, for example, a sodium excess or the accumulation of fluids in edemas leads to changes that are usually not relevant in the prediction window and can be therefore partially neglected. However, it must be emphasized at this point that the goal of this work was to find an algorithm that could be used with the existing data in a realistic scenario in daily clinical practice and that does not require additional subjective assessments or other biomarkers.In summary, the presented digital model is not based on machine or deep learning and therefore does not require large amounts of data for training and validation of the model. It allows for early recognition of a change in the CFB course, which leads to faster adjustment of treatment. The system theory model, based on single patient data, thus shows high potential for adapting and optimizing fluid management in critical care situations for a clinically feasible prediction window and could be further developed into a decision support system for fluid balance and imbalance profiling. With the here presented approach it is therefore possible to support fluid management with already existing data - with the mentioned limitations. Its advantage is its ability to reduce workload by, for example, taking over complex calculations or informing responsible clinicians of trends in changing health parameters.Additional clinical studies are needed to further improve the presented approach in terms of methodological accuracy and clinical validity by considering additional relevant clinical factors. The next steps toward a decision support system to assist clinicians with fluid management are the introduction of a feedback mechanism. The use of a dynamic, non-linear function instead of the presented TF and its embedding in a semi-closed loop could allow both the estimation of CFB trend in response to different fluid intake regimes and support the identification of the most appropriate CFI trajectory to achieve targeted CFB goals when treating individual patients.


Vaccination is the key to prevent varicella zoster virus (VZV) infection in children. Voluntary and self-funded strategies have led to variable vaccination rates against VZV in China. For low-income populations, in particular, the effects of VZV vaccination have been insufficiently estimated. Community-based serosurveillance was conducted in two less developed regions, Zhanjiang and Heyuan, of Guangdong, China. Anti-VZV IgG antibodies in serum were detected by ELISA. The vaccination data were derived from the Guangdong Immune Planning Information System. A total of 4221 participants were involved, of which 3377 were from three counties of Zhanjiang and the other 844 were from one county of Heyuan, Guangdong, China. The total VZV IgG seropositivity rate in vaccinated individuals was 34.30% and 42.76%, while it was 89.61% and 91.62% in non-vaccinated populations of Zhanjiang and Heyuan, respectively. The seropositivity rate increased gradually with age, reaching ~90% in the >20- to 30-year-old group. The VarV vaccination rates of children aged 1–14 years were 60.47% for one dose and 6.20% for two doses in Zhanjiang, and 52.24% for one dose and 4.48% for two doses in Heyuan. Compared with the non-vaccinated group (31.19%) and one-dose group (35.47%), the positivity rate of anti-VZV IgG antibodies was significantly higher in the two-dose group (67.86%). Before the VarV policy was reformed, the anti-VZV IgG positivity rate was 27.85% in the one-dose-vaccinated participants, which increased to 30.43% after October 2017. The high seroprevalence in participants was due to infection of VZV in Zhanjiang and Heyuan, not vaccination against VZV. Children aged 0–5 years are still vulnerable to varicella, so a two-dose vaccination program should be implemented to prevent onward transmission of VZV. Varicella zoster virus (VZV) is a human herpesvirus that belongs to the alpha-herpes virus family. It is a highly infectious pathogen that can be transmitted through air droplets from the respiratory tract or direct contact with varicella blister fluid ,2. VaricVaccination with the varicella attenuated live vaccine (VarV) is the most economical and effective measure to prevent varicella in children . AlthougSerosurveillance and comprehensive analysis of vaccination data may guide policy reform of vaccination programs in less developed regions of China, as well as other similar areas in Southeast Asia.The survey was conducted by stratified cluster random sampling between November 2019 and December 2020. First, three counties from Zhanjiang  and one county from Heyuan (Heping) were selected as sampling work fields using proportional to the population size (PPS), then the communities were sampled by PPS, after which residents of all age groups were selected as monitoring subjects through simple random sampling. The Guangdong provincial varicella vaccination program (2017) was suitable for children aged <14 years. The first dose should be given at 1–2 years old and the second dose at 4–6 years old. Those who did not complete the two doses at the specified ages should complete a course through emergency vaccination and the inoculation interval should be ≥3 months. The inclusion criteria for subjects were as follows: (1) a local resident for at least 3 months; (2) with good physical health; (3) for children aged 1–14 years, the brand of VarV was BCHT . The exclusion criteria for subjects were as follows: (1) refused collection of venous blood; (2) had unclear varicella vaccination information (missing date and dose of vaccination); (3) immunocompromised patients and recipients of blood and blood products during the last 6 months. A total of 4226 citizens were recruited. Five citizens were excluded as they refused to donate venous blood. Among the children aged 1–14 years old, 52 had incomplete vaccination information and were excluded from further analysis.http://10.79.0.253/nipisgd/login.action, accessed from 10 January to 10 February 2022) in Guangdong CDC, including the date and the doses of vaccination. The sampling and vaccination history were matched with the personal ID number.The basic information of the participants was collected by questionnaire survey, including age, gender, residential address, and ID number. If the participants were children, the questionnaire was filled out by their guardians. The entire varicella vaccination history of each participant aged 1–14 years was taken from Guangdong Immune Planning Information System  was taken from the participants in a local hospital. For newborns, 5 mL umbilical cord blood was collected. All blood samples were initially centrifuged at 3000 rpm for 5 min. The serum was transferred to a new sterilization tube marked with the sample name and date of blood collection. All serum samples were frozen at –20 °C until testing.Enzyme-linked immunosorbent assay (ELISA) was performed on all samples using the SERION ELISA classic Varicella zoster virus IgG antibody detection kit  to test the presence of anti-VZV IgG. The experimental procedure was conducted strictly according to the kits’ manual instructions. The standard serum with anti-VZV IgG in PBS was the positive control and the negative control was PBS without anti-VZV IgG. The serum samples were initially diluted at a ratio of 1:100 and then 100 µL of dilution was added to the determination plate for 1 h incubation at 37 °C. After incubation, the plate was washed with an automatic plate washing machine  using lotion buffer solution, repeated four times. This was followed by 100 µL IgG enzyme-labeled antibodies being added to each well and then incubated at 37 °C for 30 min. After one-cycle washing step, 100 µL of each substrate was added to each well and incubated again at 37 °C for 30 min. Finally, 100 µL of termination solution was added. All the ELISA results were determined using an enzyme-labeled instrument , and the data were presented as the OD  value at the wavelength λ = 405 nm. The cutoff value refers to the manual instructions. An OD value above the cutoff value was considered positive. The OD value for children aged 1–14 years with anti-VZV IgG positive was converted to the antibody concentration values (mIU/mL) using software from SERIO. The test range of the kit was 50–2000 mIU/mL. The results greater than 2000 mIU/mL were labeled as 2000 mIU/mL.p < 0.05 was considered statistically significant.All data information was introduced into combined Excel files and analyzed by SPSS version 20.0 software . The anti-VZV IgG positivity rate in different cities, age groups, and vaccination histories was compared by Chi-square test. The geometric antibody titers (GMCs) of different groups were compared by one-way ANOVA, and multiple comparisons were performed using the LSD test. A total of 4221 participants were enrolled in the study. Among them, 3377 were from Zhanjiang , including 1263 men (37.40%) and 2114 women (62.60%). The remaining 844 were from Heping, Heyuan, including 366 men (43.36%) and 478 women (56.64%) . In addi2 = 0.224, p = 0.621), respectively  and Heyuan , whereas no significant difference within the same age groups was found between the two cities  participants had no vaccination history for VarV from Zhanjiang and Heyuan. The serum anti-VZV IgG positivity rates of participants across all age groups were 89.61% (11.63–96.80%) and 91.62% (22.00–97.75%) in Zhanjiang and Heyuan  . Compared with the two-dose group, the positivity rate of anti-VZV IgG in the one-dose group was also significantly higher   . No sign= 0.019) .The participants aged 1–14 years who were anti-VZV IgG positive were divided into three groups: non-vaccinated (zero dose), one dose, and two doses. There were 63 participants with no vaccinations, 105 participants with one dose of vaccination, and only 19 participants with two doses of vaccination .p = 0.818). However, the anti-VZV IgG level of the 63 non-VarV participants was higher than that of the one-dose group  (p = 0.252)  A,B. No s= 0.252) A,C.p = 0.954; one dose, F = 1.376, p = 0.257)  D,E.2 < 0.001, p = 0.625).In October 2017, the Guangdong CDC officially issued the Guangdong provincial varicella vaccination program for children (2017). Before 2017, Guangdong provincial public authorities suggested that children over 1-year old receive one dose of varicella vaccination . In thisIn 2014, the estimated nationwide vaccination rate of varicella in children was only 20.84% in China . In GuanThis study was conducted to understand the status of VZV infection and to assess the effects of anti-VZV vaccination in Zhanjiang and Heyuan. First, we found that the seropositivity rate of anti-VZV IgG in newborns reached 85%, which was obtained through vertical transmission from mothers. These data are similar to those from a study in Korea , in whicWe found that the one-dose VarV vaccination rates in participants aged 1–14 years from Zhanjiang and Heyuan were 60.47% and 52.24%, respectively, which are comparable to those in Suzhou (66.79%) and Hangzhou (70.06%) ,38. HoweIn this study, we found that the anti-VZV IgG level of non-vaccinated children was higher than that of the one-dose children. We believed that this may be because non-vaccinated children may experience a natural infection of VZV during varicella outbreaks in their kindergartens and primary schools. We also determined the persistence of anti-VZV IgG induced by VarV vaccination. The results showed that the anti-VZV IgG persisted for 5 years in children after one dose of varicella vaccination. However, a report from Jiangsu province showed that the titers of varicella antibody decreased gradually after vaccination . Cohort Reform of the vaccine immune program may impact the dynamics of population vaccination. In 2006, the Advisory Committee on Immunization Practices (ACIP) recommended a routine two-dose varicella immunization schedule, and it was employed first in the USA ,46,47. MThere were some limitations to this study. First, breakthrough infection of VZV in vaccinated participants was not assessed due to the limited number of participants in Guangdong. Second, the influence of factors that may affect the vaccination of VarV was not included in the analysis in this study, e.g., income and education level. Third, this study was a term cross-sectional study, which can describe the characteristics of varicella immunization of different groups but cannot draw a conclusion on the dynamics of both varicella and VarV vaccination. Finally, we only sampled the serum of participants from Zhanjiang and Heyuan. Geographical differences should be considered in further studies.In this study, we determined the population seroprevalence of varicella in healthy people from Zhanjiang and Heyuan, and we found a high anti-VZV IgG positivity rate in teenagers and adults. However, the positivity rate of anti-VZV IgG was low in children aged 0–5 years. A comparison assay between vaccinated and non-vaccinated populations indicated that the high seropositivity was due to natural infection of VZV in teenagers and adults, not persistent anti-VZV IgG induced by vaccination. Nevertheless, two doses of varicella vaccine are essential for children in low-income regions. A comprehensive analysis incorporating varicella incidence data will be essential to assess the protection effects of VarV vaccination in the real world in future.