This paper investigates the influence of silt content and coarse particle content on the mechanical and physical properties of foamed concrete, including compressive and flexural strength, modulus of elasticity, water absorption, drying shrinkage, and air-void structure. Four types of silt with different coarse particle contents were obtained by soil mixing. The results showed that high density, low silt content, and high coarse particle content can provide better mechanical properties. High silt content and high coarse particle content would lead to lower drying shrinkage. Silt content was the main factor affecting the pore distribution of foamed concrete, and higher coarse particle content could optimize the air-void structure. Meanwhile, the change in air-void structure can accordingly affect the water absorption of foamed concrete. Results showed that, at the same density and silt content, higher coarse particle content can optimize the physical and mechanical properties of foamed concrete. It has the characteristics of light weight  was adopted. Physical properties of the cement and the chemical composition of the cement are listed in The raw materials used in this experiment were silt and clayey silt from Dongying, China, and the experimental soil was made by mixing the two raw materials in a certain proportion. Some other parameters are shown in Coarse particle content (CPC) refers to the ratio of the soil particle mass with particle size greater than 0.075 mm to the total mass of the soil sample. Four kinds of soil samples with coarse particle contents of 25%, 30%, 35%, and 40% were studied, and the particle size distribution curves of the four different coarse grain contents are shown in The foaming agent used in the test was a protein-based anionic foaming agent produced by Chilong Building Energy Saving Technology Co. Ltd. . The dilution ratio was 35–45 times and the foaming ratio was 800–1000 times.The mix proportions with three different series of density, silt content, and coarse particle content are shown in the 3 to 800 kg/m3. The silt content (SC) was 20% and coarse particle content (CSC) was 25%, where SC is the mass of the silt divided by the total mass of the solid. Series II was used to study the influence of silt content on the performance of foamed concrete. The silt content ranged from 0 to 40%. The wet density was 700 kg/m3 and the coarse particle content was 25%. As seen in the In The sample preparation process is shown in Compressive strength, flexural strength, and elastic modulus were measured following the Chinese GB/T 11969-2008 standard . AccordiAccording to the Chinese JG/T266-2011 , a cube A rectangular specimen with a size of 40 mm × 40 mm × 160 mm was selected to conduct the drying shrinkage test . In the 2 were analyzed for each mix. After the images were captured, Image Pro Plus 6.0 image processing software  was adopted to analyze and process the microscopic images. The pore size, area, and other parameters of each pore were calculated through the software.The 28-day air-void structure was investigated using scanning electron microscopy (SEM). The instrument used in this experiment was the S-4800 ultra-high-resolution scanning electron microscope produced by Toshiba in Japan, which uses a magnification ratio of 30×. Three images covering an area of 38.7 mm3. This is because, as the density increased, the foam content in the mixture decreased and the content of cement that provided the strength increased. This pattern is similar to the results of foamed concrete mixed with clay obtained by Ma and Chen [As shown in and Chen .The SEM results in It can be seen from It can be seen in Silt existed independently in foamed concrete and did not react with the cementitious system, which acted as a skeleton support inside the air-void structure, as well as a cheap filler for cementitious materials. With the increase in coarse particle content of silt, the mechanical properties of foamed concrete showed a tendency of gradual increase. On the one hand, when the silt particle size was prevalent, the particles were compact, which could better play the role of skeleton. On the other hand, when the coarse particle content of silt was prevalent, the water absorption and the viscosity of silt were relatively large. In the mixing process, too many fine particles made it easy to form flocculent and spherical accumulation. As a result, the air-void structure was destroyed, and the mechanical properties of foamed concrete were reduced.As can be seen from Under the same density and silt content, upon comparing the four coarse particle contents in the SEM image, as seen in According to (1)High density, low silt content, or high coarse particle content led to better mechanical properties. The mechanical properties can all meet the requirements of the Chinese standard .(2)Silt content was the main factor affecting the pore distribution of foamed concrete, and the addition of silt had an adverse effect on the air-void structure of foamed concrete. The change in air-void structure caused by the addition of silt correspondingly affected the water absorption rate.(3)High silt content and high coarse particle content led to lower drying shrinkage. It is, thus, necessary to select an appropriate silt content according to the actual requirements.(4)3, silt content of 40%, and coarse particle content of 40%.Considering the material performance and economy, it is recommended to use foamed concrete with a wet density of 700 kg/mTaking density, silt content, and coarse particle content into consideration, the mechanical and physical properties of silt-based foamed concrete were investigated. The experimental results of this investigation revealed the feasibility of widely applying silt-based foamed concrete, and the following conclusions can be drawn:According to the investigation, higher coarse particle content would optimize the physical and mechanical properties of foamed concrete. However, this was only studied within the range of 25–40%. In a further investigation, silt with a wider range of coarse particle content needs to be added to the foamed concrete to explore whether there could be an inflection point in cases of the larger coarse grain content not being known.


The concentrations of nitrite and thiocyanate in saliva can be used as the biomarkers of the progression of periodontitis disease and environmental tobacco smoke exposure, respectively. Therefore, it is particularly necessary to detect these two indicators in saliva. Herein, the three-dimensional single-layered paper-based microfluidic analytical devices (3D sl-μPADs) were, for the first time, fabricated by the spraying technique for the colorimetric detection of nitrite and thiocyanate at the same time. The conditions for 3D sl-μPADs fabrication were optimized in order to well control the penetration depth of the lacquer in a paper substrate. Then, the developed 3D sl-μPADs were utilized to simultaneously detect nitrite and thiocyanate and the limits of detection are 0.0096 and 0.074 mM, respectively. What is more, the μPADs exhibited good specificity, good repeatability, and acceptable recoveries in artificial saliva. Therefore, the developed 3D sl-μPADs show a great potential to determine nitrite and thiocyanate for the assessment of the human health. Paper-bIn recent years, three-dimensional (3D) μPADs, especially single-layered configurations, have become a growing research field in μPADs. Compared to the 2D configuration, the fluid in 3D channels can flow in both lateral and vertical directions, making it possible to manipulate complex fluid flow and design complicated chips . Most of2+ assay is very good, and the limit of detection is as low as 8.5 μM [Spraying-based technology has been developed for the fabrication 2D μPADs in recent years. With a comparison to the conventional fabrication techniques, a spraying process displaced the printing process to fabricate 2D μPADs, attracting wide interest of researchers. Nurak et al. constructed 2D μPADs to detect nickel (II) ion by a spray-painting method. The analytical performance of Nis 8.5 μM . Cardosos 8.5 μM . Our gros 8.5 μM . Althougs 8.5 μM . Their wIn this work, a spraying patterning approach is presented for the fabrication of 3D sl-μPADs relying on double-sided spraying of lacquer. Two important parameters for the fabrication process were optimized: (1) spraying times (the times needed for pressing the spray nozzle), and (2) drying conditions including temperature and time. Under the optimized fabrication conditions, 3D channels were formed in a single piece of paper. The applicability of the fabricated 3D sl-μPADs was demonstrated by simultaneously detecting nitrite and thiocyanate. The results show satisfactory sensitivity, good specificity, good repeatability, and acceptable recoveries in artificial saliva toward nitrite and thiocyanate detection.2 per can of lacquer. The desired mask was designed using Auto CAD software and cut out from transparent polymethyl methacrylate (PMMA) board with 1 mm in thickness by a local laser cutting shop in China. Black paper binder clips (size 19 mm) were purchased from Deli Co., Ltd.  and used to fix the desired mask on the filter paper. Sodium nitrite, potassium thiocyanate, sulphanilamide, N-(1-naphthyl) ethylenediamine dihydrochloride (NED), ferric nitrate nonahydrate, citric acid monohydrate, boric acid, sodium hydroxide, glacial acetic acid, phosphoric acid, sodium carboxymethylcellulose (SCMC) were of analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd. . Poly (acrylic acid) (M.W. ≈3000) was bought from Aladdin-Reagent Company . Ultrapure water with electric resistivity of 18.2 MΩ cm was used throughout. The digital photos of the developed assays were taken by a smartphone  in a foldable photo box. The photo box is equipped with 84 LED lamps and lampshade with the size of 40 × 40 × 40 cm. The distance between the phone and the fabricated 3D sl-μPADs was 8 cm. The digital Red (R), Green (G), and Blue (B) color analysis was done by ImageJ software provided by National Institute of Health .The qualitative filter paper (102#) with medium speed was bought from Hangzhou Fuyang Wood Paper Co., Ltd.  and used for 3D sl-μPADs fabrication. The porosity of the filter paper was 15–20 μm and the ash content of the filter paper was less than 0.15%. The thickness of the filter paper was measured to be 170 μm using a digital vernier caliper. The lacquer  was purchased from Guangdong Haoshun ODIS Technology Co., Ltd. . The principal component of the lacquer is resin and the lacquer has the advantages of high water resistance and good adhesion. The spraying area is 2.5 m2− and SCN− standard stock solutions were made by the dissolvement of NaNO2 and KSCN in ultrapure water, respectively. The Griess reagent for NO2− detection was made up of 330 mM citric acid, 50 mM sulfanilamide, and 10 mM NED. The Fe (III) reagent solution (600 mM) for SCN− assay was made by the dissolvement of ferric nitrate in Britton–Robinson buffer (pH 7). For the recovery test, the artificial saliva was used as the complex sample, consisting of the following in ultrapure water: NaCl 0.4 g/L; KCl 0.4 g/L; CaCl2·2H2O 0.8 g/L; NaH2PO4 0.69 g/L; Na2S·9H2O 0.05 g/L; SCMC 0.1 g/L [The NO 0.1 g/L ,37.The spraying prototyping process for fabricating the 3D sl-μPADs was illustrated and shown in 2− and SCN− was performed. The detection reservoirs on the left were used for nitrite assay and the detection reservoirs on the right for thiocyanate detection. A total of 18 µL of the standard containing two anions was pipetted into the central reservoir for introducing the sample. After a 15-min waiting period, the image of the device was collected with a phone camera in the professional photography box. The color intensities in the RGB mode were measured by the free software, ImageJ. The whole area of the assay zone was selected, and the mean color value was calculated.The detection principles for nitrite and thiocyanate assays are based on the classical Griess diazo-coupling reaction and the coordination reaction between Fe (III) and thiocyanate, respectively ,39,40. BFor the recovery test, the fabrication process of the 3D sl-μPADs was the same as the experimental steps referred to before. The artificial saliva sample was used as the complex sample to detect the recoveries. The addition of SCMC in the artificial saliva was used to mimic human saliva viscosity . The comSpraying technique is effective at penetrating the lacquer vertically through the cellulose pore spaces and thereby forming a hydrophobic barrier . LimitedIn this work, the 3D sl-μPADs were generated by the spraying prototyping process. To investigate the penetration degree of the lacquer at different regions, the solution containing red food dye (18 µL) was added to the central well of the developed device. Then the solution filtered through the paper, traveled through the filter paper along the channel route, and reached the side wells. Then the fabricated 3D sl-µPADs were cut along the black dotted line after they were fully dried as shown in Furthermore, the wettability behavior of the 3D sl-µPADs was studied. The photographs of water droplet (4 µL) on both sides of the 3D sl-µPADs are shown in w/v) cetyltrimethylammonium bromide (CTAB)) and organic solvents (50% (v/v) isopropanol). In order to visually demonstrate the barrier effectiveness, the distance-based μPADs were used with a circular sample introduction zone (8 mm in diameter) and a straight channel (2 mm in width × 25 mm in length) for the resistance experiment. The solution containing a red food dye was pipetted into the sample introduction zone. After drying for 20 min, the optical micrographs of the channels were recorded. The results are shown in The barrier resistance is one of the important evaluation criteria for μPADs. The chemicals including acid and alkaline solutions, organic solvents, surfactants, etc., were often used in the analytical experiments. Therefore, the resistance of the lacquer barrier towards these chemicals was examined in this work. The solutions used for resistance examination are listed as follows: ultrapure water, acidic solutions , alkaline solution (150 mM sodium hydroxide), surfactants  and Blue channel intensity = − 8.9016Cthiocyanate + 70.4588 (R2 = 0.9907) for nitrite and thiocyanate, respectively. The limits of detection (LOD) calculated as the threefold noise level of the blank signal were 0.0096 and 0.074 mM for NO2− detection and SCN− detection, respectively. The performance of the developed 3D sl-µPADs was compared with other sensors reported in literature for nitrite and thiocyanate assays as shown in The simultaneous detection of nitrite and thiocyanate by the 3D sl-µPADs was investigated. The images of the detection zones after the addition of a series of standards are shown in 4+, CH3COO−, I−, H2PO4−, Cl−, SO42−, Mg2+, Br−, NO3−). The specificity of the developed 3D sl-μPADs was investigated by performing the control experiments using other commonly ions as interferents (NHThe practicability of the fabricated 3D sl-μPADs was evaluated by carrying out the recovery test using the artificial saliva as the real sample. The artificial saliva was spiked with the solutions with known concentrations of nitrite and thiocyanate, and was then pipetted into the central reservoir. The photos were acquired after 15 min of sample addition to allow full reaction between the analytes and the reagents. The results of the recovery test in artificial saliva are listed in In conclusion, the spraying technique was, for the first time, applied for manufacturing single-layered 3D μPADs. Under the optimized fabrication conditions, 3D channels were successfully constructed in a single piece of filter paper and the hydrophobic boundary was very clear. Furthermore, the developed 3D sl-μPADs were demonstrated for the determination of nitrite and thiocyanate at the same time. The linear ranges are 0.02–2 mM and 0.25–5 mM and the LODs are 0.0096 and 0.074 mM for nitrite and thiocyanate, respectively. Moreover, the 3D sl-μPADs exhibit good specificity, good repeatability, and satisfactory recoveries in the artificial saliva. The analytical performance of the 3D sl-μPADs is sufficient to detect nitrite and thiocyanate at the levels normally found in saliva, indicating their potential applications in POCT. More importantly, through changing the designs of PMMA boards, the 3D sl-μPADs could accommodate more complex channels and enable high-throughput detection.


In this article we present the development of a biosensor system that integrates nanotechnology, optomechanics and a spectral detection algorithm for sensitive quantification of antibiotic residues in raw milk of cow. Firstly, nanobiosensors were designed and synthesized by chemically bonding gold nanoparticles (AuNPs) with aptamer bioreceptors highly selective for four widely used antibiotics in the field of veterinary medicine, namely, Kanamycin, Ampicillin, Oxytetracycline and Sulfadimethoxine. When molecules of the antibiotics are present in the milk sample, the interaction with the aptamers induces random AuNP aggregation. This phenomenon modifies the initial absorption spectrum of the milk sample without antibiotics, producing spectral features that indicate both the presence of antibiotics and, to some extent, its concentration. Secondly, we designed and constructed an electro-opto-mechanic device that performs automatic high-resolution spectral data acquisition in a wavelength range of 400 to 800 nm. Thirdly, the acquired spectra were processed by a machine-learning algorithm that is embedded into the acquisition hardware to determine the presence and concentration ranges of the antibiotics. Our approach outperformed state-of-the-art standardized techniques (based on the 520/620 nm ratio) for antibiotic detection, both in speed and in sensitivity. The growth of the world population has required the food industry to increase its productivity and improve food safety. Milk consumption either before or after thermal processing has several health risks associated with the presence of contaminants such as thermoresistant mycotoxins and antibiotic residues. Antibiotics are primarily used in dairy farms for the treatment of mastitis and other infectious diseases . The WorIn Chile, the Servicio Agrícola y Ganadero (SAG) and the Ministerio de Salud (MINSAL) are the institutions responsible for ensuring the sanitary inspection and control of veterinary pharmaceutical products. The MINSAL implements a national plan to control the presence of antibiotic residues in dairy products, referred to as “Surveillance program for residues of veterinary medicines”. This program supervises the Maximum Residual Limits (MRLs) of veterinary drugs potentially present in Chilean products . Milk coCurrently, “screening kits” are used in dairy plants for rapid antibiotic residue testing in milk, which include Delvotest®   are one of the most promising label-free sensor systems ,15. The Novel NBS based on gold nanoparticles (AuNPs) for antibiotic detection in milk have been previously reported ,17,18. AIn this article, the development of a technological solution to the problem of detecting antibiotic residues in raw milk is presented.Current methods for the detection and/or determination of antibiotics in milk are divided into two major categories. The first group consists of screening methods, which are economical and easy to use. However, these methods are qualitative  or semi-quantitative  and are characterized by having low sensitivity and low specificity . Charm® families . The secfamilies . These mThe proposed device integrates optomechanical and optoelectronic components  to measure the variation in the absorption spectrum of the milk that is induced by the interaction between the NBS and the antibiotic molecules. Importantly, the device implements a machine-learning algorithm to simultaneously analyze optical signals from multiple samples (in a microwell plate) and determine the corresponding antibiotic concentrations.The paper is organized as follows. The methodology used to synthesize the NBS and the analytical conditions  are shown in the beginning of This section depicts important aspects of the methodologies that are implemented in this work to perform the detection of antibiotics in raw cow milk.NBS employed in this study are devises using gold nanoparticles (AuNPs) and aptamers that specifically recognize (detect) the selected antibiotics and allow the selective aggregation of the nanoparticles, which otherwise would be a spontaneous phenomenon in aqueous solution. AuNPs were synthesized using the citrate reduction method, maintaining the synthesis pH between 5.3 and 6.0 . Herein,aptamers , accordi3 0.6 M and incubated at 60 g for 10 min and the resulting supernatant was recovered for the NBS experiments. In order to generate absorption spectral databases, tests were carried out in 96-well plates of clarified milk with the aforementioned concentrations for the four selected antibiotics. Finally, the NBSs were added into the clarified milk and NaCl was incorporated to trigger aggregation of the AuNPs .This is a heterogeneous fluid held in multi-dispersed phases of emulsion (fat–water), colloidal suspension (protein–water) and solution . Samples were prepared before applying any NBS analysis, using raw milk that was kindly facilitated by the company Leches del Bio-Bio S.A. Thus, the antibiotics Kanamycin, Ampicillin, Oxytetracycline and Sulfadimethoxine were first added into the samples at concentrations of 0.25, 0.5, 1, 1.5 and 2 times the MRL, according to the Chilean regulation in 2019 . We also∘C) ,28. As a∘C) , accordiIn this section we describe a built-in electro-opto-mechanic prototype that acquires the spectra of the individual samples in the microplate, processes the data and correlates the measured spectrum with the concentration of the measured antibiotic.The hardware of the prototype is shown in The data acquisition and control software were developed in LabView, which allowed to define the wells to be measured and the position of the reference sample. To start the measurements, the optomechanic system moves the 96-well microplate to correctly align the reference well with the instruments, then turning on the reference well and user-defined wells are covered. The light source is subsequently turned on and the resulting transmission spectrum for each sample are acquired.We denoted the incident radiation generated by the light source as To reduce the effect of spectral variations of the the samples caused by small optical misalignment, sample bubbles and vibrational disturbances, the acquisition system performs multiple absorbance measurements for each well and averages the spectra before reporting the NBS spectrum.At this stage, for each of the four antibiotics we obtained multiple measurements for each fraction of the MRL concentrations, as shown later. In what follows, we explain the procedure employed to correlate this measured spectra with the concentration of the antibiotics.j stands the j-th antibiotic to be detected  classifiers to determine the presence and the level of antibiotics concentration for a given spectrum. According to the Chilean regulation, we defined three classifiers: one to determine whether the sample has antibiotic or not (SVM 0), one to determine if the sample has antibiotic with a concentration below the MRL (SVM ≤ 1.0) and another to determine whether the sample has a concentration of antibiotic above the MRL (SVM ≥ 1.0). In The concentration assigned to each spectrum corresponds to the majority determined through the output of each of the classifiers. This is known in the literature as a “one-against-all” decision tree with a majority decision rule “winner-takes-all”.In order to train the algorithms that determine the presence and concentration level of the different antibiotics, we utilized the absorption spectra of clarified milk. The NBSs for each antibiotic were incubated in clarified milk contaminated with different concentrations of antibiotics, namely 0 ppb of antibiotic (milk without antibiotic), 25% of the MRL, 50% of the MRL, the actual MRL of the antibiotic, 150% the MRL and 200% the MRL. It is understood that if the concentration of an antibiotic is higher than the MRL, then the raw milk does not comply the legal regulations.For each of the aforementioned concentrations, we performed several experiments and measured the corresponding absorption spectra. There are 60 samples per antibiotic that contain 5 levels of concentration. Each of these experiments required the full process of NBS construction, contamination of the raw milk with each antibiotic at the given concentration, clarification of the contaminated raw milk, interference reduction and the acquisition of the absorbance spectra by the built-in instrument.In From the present results, considering a classification with a 100% success rate and that the NBSs were developed specifically to interact with each individual antibiotic, it is determined that the specificity of the NBS is 100%, by design, for all antibiotics. The specificity of the algorithm for estimating different concentrations was 100% for Kanamycin, 99.12% for Ampicillin, 91.67% for Oxytetracycline and 99.17% for Sulfadimethoxine. For Kanamycin, the sensitivity reached was 100%. For Ampicillin, the maximum sensitivity reached was 95.65%, with an average of 88.83%. For Oxytetracycline, the maximum sensitivity reached was 91.67%, with an average of 88.33%. Finally, for Sulfadimethoxine, the maximum sensitivity obtained was 95.83%, with an average of 91.48%. The linear range of all classifiers is 0 times MRLs up to 2 times the MRL. For all antibiotics, the detection limit was 0.25 times the MRL, corresponding to 37.5 ppb for Kanamycin, 1 ppb for Ampicillin, 25 ppb for Oxytetracycline and 6.25 ppb for Sulfadimethoxine, see The data were analyzed through the standard methodology in order to compare the results (see a detailed description in ). The trFinally, these results offer insight into the capability of the technology to provide confirmatory analysis for screening tests that are routinely applied in farms/diaries for rapid detection of antibiotic residues in raw milk  classifiers to determine the presence and concentration levels for the antibiotics, outperforming in sensitivity the typical metrics based on the absorbance ratio. The SVM-based classification algorithm allowed to reach a detection limit of 0.25 times the MRL, with a linear range from 0 to 2 times the MRL for each antibiotic.Overall, this technology offers a combination of portability and sensitivity that supports further development in the field of confirmatory analysis for screening tests applied in farms and diaries to detect antibiotic residues in raw milk.


Antibiotic resistance is a global problem affecting both human and animal health. Ensuring the strategic and effective use of antibiotics is paramount to combatting the emergence and spread of resistance. This study explored New York State (NYS) dairy farmers’ perceptions regarding antibiotic use in dairy farming and antibiotic resistance. Dairy farmers’ perceptions were assessed through semi-structured, in-person interviews. Twenty interviews with farm owners and/or managers of 15 conventional and five USDA certified organic dairy farms with 40 to 2,300 lactating cows were conducted. Thematic analysis was used to assess, compare and contrast transcripts for farmers’ characterization of their beliefs, values, and concerns. Conventional dairy farmers had a low level of concern about the possible impacts of on-farm antibiotic resistance on human health and believed their antibiotic use was already judicious. Generally, they believed their cattle’s health would suffer if antibiotic use were further curtailed. Conventional farmers expressed frustration over the possibility of more stringent governmental, milk cooperative, buyer, or marketer requirements for antibiotic use and associated animal welfare in the future. They attributed expanding regulations in part to misinformed consumer preferences, that farmers felt were influenced by the marketing of organic dairy products. Organic dairy farmers were generally more concerned about issues related to antibiotic resistance than conventional farmers. Both conventional and organic farmers placed emphasis on disease prevention through herd health management rather than treatment. In conclusion, the conventional NYS dairy farmers in this study were skeptical of the need for and benefits of reduced antibiotic use on their dairy farms. Interventions for farmers, delivered by a trusted source such as a veterinarian, that provide training about proper antibiotic use practices and information of possible financial benefits of refining antibiotic use may hold promise. Salmonella and drug-resistant Campylobacter as serious health threats . Oth. Oth2].  threats . In addi animals  5] 6]. [6].Salm. [6].Sal animals .Given the various potential routes of human exposure to antibiotic-resistant bacteria from animal agriculture, it is prudent to consider how to optimize antibiotic use in animal agriculture in order to minimize the development of antibiotic resistance. Farmers are important stakeholders in such discussions, especially since they are likely to experience any negative consequences that arise as a result of attempts to alter antibiotic use. Concerns have been raised that the push to reduce antibiotic use could have negative unintended consequences on food safety, animal health, production, and the economic viability of farming . DespiteThe subject of dairy farmers’ perceptions of their antibiotic use has received even less attention than their perceptions of antibiotic resistance. One study of Wisconsin dairy farmers found that 80% believed they used the “right amount” of antibiotics . This asWithin dairy farming, adopting new strategies for mastitis treatment and control has the potential to reduce overall antibiotic use. Intramammary antibiotics are frequently used for both the prevention and treatment of mastitis. Related to that, pathogen-based  treatment of mastitis has garnered much interest. Using this strategy, milk from cows suspected of having mastitis is cultured and treatment decisions are made based on the results. According to a 2014 study conducted by the United States Department of Agriculture (USDA), 40.6% of US dairy operations use culture and antimicrobial sensitivity testing to guide antibiotic treatment . CompareThe use of antibiotics at dry-off (cessation of lactation) has also been considered as an area for potential antibiotic use reduction . BlanketDespite opportunities for change, previous research with U.S. dairy farmers suggests that they are not concerned about the impact of antibiotic use or overuse on the development of antibiotic resistance in dairy cattle or humans  11]. In. In11]. Strict regulations govern dairy farmers’ use of antibiotics. Namely, legislation requires milk from cows treated with certain antibiotics to be discarded instead of sold for profit. On top of this loss of profit, there are steep penalties in the event of a violation. Milk from cows treated with some drugs must be withheld from markets for a given length of time to ensure that drug residues do not occur in milk . The PasAs previously noted, dairy farmers’ perceptions of recently-implemented U.S. regulations regarding antibiotic use have received limited exploration, particularly in NYS. In response to concerns about the development of antibiotic resistance due to antibiotic use in animal agriculture in the U.S., the U.S. Food and Drug Administration (FDA) fully implemented changes described in their Guidance for Industry 213 (GFI 213) document on January 1, 2017 . The twoThe objective of this study was to explore New York State (NYS) dairy farmers’ perceptions regarding antibiotic use and resistance in dairy farming, including in light of the recent implementation of the VFD. Dairy farming is a major agricultural industry in the U.S.; NYS is the third largest dairy producer in the country . We specPurposive sampling  was usedF.L.W was asked to gather a list of dairy producers with a broad range of characteristics including farm size, management style and production philosophy . F.L.W. created a list of 25 farms to contact for interviews, including farms of variable sizes and management styles to reflect the scope of dairy farms in NYS. Those identified were then recruited in one of two ways: (1) they were contacted via telephone by F.L.W. who described the study and assessed willingness to participate before providing the interested farmers’ contact information to the first author (M.W.) or (2) they were contacted via telephone directly by M.W. The first 20 farms for which contact with a person was made via telephone agreed to participate in the study. Interview dates and times were arranged by the interviewer (M.W.). Interviewees chose their preferred location of the interview, which was generally their farm and/or home.A semi-structured interview guide  was deveInitially, the study focused only on conventional dairy farmers and excluded organic farmers from enrollment because of restrictions on antibiotic use placed on farms with USDA organic certification. However, after 12 interviews with conventional dairy farmers, which included mention of organic practices, the research team recognized that including organic farmers would permit a more nuanced understanding of dairy farmers’ perceptions. A decision was made to enroll organic farmers along with conventional farmers. At the same time, based on iterative analysis and emerging themes, the interview guide was modified to explore in more depth specific topics identified during the first 12 interviews. The second version of the interview guide  was admiWhile major topic areas of the interview guides were covered during interviews, as a result of participant time constraints and the open-ended nature of the questions, not all individual questions or prompts were always addressed in each interview. Due to time and resource availability the enrollment was stopped when we reached 20 interviews, at which point saturation on many topics was also reached. Saturation was deemed to be reached when no novel themes emerged during analysis of the last few interviews.Semi-structured interviews were conducted during June and July of 2017 and 2018 by the first author (M.W.), who is also a veterinary student enrolled at Cornell University’s College of Veterinary Medicine. They were conducted in person at participants’ farms and intended to be approximately one hour in length. Interviews lasted between 27 minutes and 89 minutes with a median of 54 minutes. Participants provided written consent at the start of the interview. The interviews were audio recorded and transcribed by the Survey Research Institute of Cornell University. The study was approved by the Cornell University Institutional Review Board for Human Participants (IRB protocol #1705007138).Interviews were analyzed using thematic analysis  using QSBasic descriptive statistics were produced using Microsoft Excel to describe the study participant characteristics. Most participants described the size of their farms in terms of the number of lactating cows on the farm. In interviews where only information on the number of cattle over 12 months of age was obtained, that quantity was multiplied by 0.70 to obtain an estimate for the number of lactating cows. If participants gave ranges, the mean of the upper and lower numbers was taken. The value of 0.70 was obtained by determining the mean percent of cows over 12 months of age that were lactating using information from five farms that provided both their number of cattle over 12 months of age as well as their number of lactating cows. It is also supported by dairy industry information .As is shown in Theme 1: Among conventional farmers, concerns about antibiotic resistance do not rank highly, what is most salient is near term impacts to their livestock should antibiotics lose their efficacyFarmers generally properly defined both antibiotics and antibiotic resistance. Descriptions of antibiotic resistance often incorporated explanations of how bacteria could become resistant to antibiotics or how it resulted in loss of effectiveness of the antibiotic. Two participants, however, provided explanations of antibiotic resistance that were not fully correct, describing antibiotic resistance as the animal “resisting” the antibiotic or becoming “immune” to it. When asked to elaborate their understanding of antibiotic resistance, some participants associated the term antibiotic with regulation, withholding periods, lost revenue, antibiotic resistance (an organic participant), and/or the ability to save a cow.Conventional farmers do have concerns surrounding antibiotic use and resistance, particularly for their animals’ health if an antibiotic no longer “works”.“Either using the same drug all the time, or using blanket treatments, I think are both pretty dangerous for introducing the antibiotic resistance. I mean, from way back—and that’s been a concern in human medicine, but then also in animals—about having less and less drugs that are available to be treatments to things.” Conventional participants expressed various levels of concern about antibiotic resistance on the farm level. Some said their level of antibiotic use was very low, so it was not a major concern for them. In regard to potential impacts of antibiotic use in dairy cattle on human health, most participants expressed little concern about possible impacts occurring either via antibiotic resistance or antibiotic residues in milk, but did note concern about on-farm impacts.“Not with the drugs that we are using. Unless somebody told me that one of the three drugs that we use is critical for treating some humans somewhere—if I was to find that out, then I would be concerned. That’s not the case to the best of my knowledge at this point, so I’m not.” “Then the fourth [benefit of using less antibiotics] might be antibiotic resistance. In other words if you are over using it, then it’s not going to work for you anymore. Like I said, it’s more people on the human side that are concerned about that. If we are using too much medicine in our cows it’s going to somehow create a bacteria or something that’s going to affect humans and we won’t have the right drug to treat it in humans. I should be concerned, but I’m not overly concerned about that. But, I’m concerned about my herd, if you were overdoing it, then that would at some point make it ineffective.” It is unclear whether conventional participants concerned about antibiotic resistance on dairy farms thought humans could be impacted by this. One such participant was unaware that there was concern about the impacts of antibiotic resistance in agriculture negatively impacting humans. Other responses to the term antibiotic resistance included that it was “overhyped” and that it meant new antibiotics needed to be developed.“Sometimes I think it’s [antibiotic resistance] a little bit overinflated but obviously I’m not a doctor or vet to know… What you can do but… Sometimes I think it’s overhyped.” Some mentioned concern about antibiotic resistance, but it was in the context of human healthcare, overprescribing by physicians and not connected to animal agriculture:“I don’t know if I’d have an opinion on any resistance. It would be more likely from the human-side of things. I mean, not the animal-side of things. There’s no antibiotics in any milk, so overprescribing, I guess, would be the biggest cause of resistance in the human population.” “So that’s why I said, like having people are concerned of going to the hospital, the doctor came in and said, “It’s a strain that’s hard to treat.” I would say, “Oh no, I’ve read about these.” Or, “No, I knew somebody that had it.” But as far as on the farm, I don’t hear just a lot. I guess it’s a conversation the vet and I haven’t really had. I feel I use that little antibiotics on the farm that I don’t have that much of a fear of antibiotic resistant disease.” Finally, when asked how antibiotic resistance ranked among other operational concerns, farmers responded they were generally addressing more immediate concerns.“Low [laughs]. We are mostly worried about keeping the tractors going.” Antibiotics were a major source of concern when it came to residues getting into the milk supply. In response to a question how antibiotic use ranks relative to other concerns about managing a dairy farm, one farmer answered this way with “it” being about residues.“It’s probably the biggest concern I have as far as what could go wrong in a day. Selling a treated cow, or putting a treated cow in the milk supply. It’s pretty well-managed so I don’t lose sleep over it. But it is probably the top concern I have as far as what could go wrong during a day, besides the cows getting out.” Theme 2: Conventional farmers perceive their existing use of antibiotics as meeting “judicious use” standards and that further reductions would threaten animal welfareMost conventional participants interpreted judicious antibiotic use to mean using antibiotics only when needed, not more or less frequently. The following quote is representative of the feedback we heard:“Think. Think before you use it. I mean, only use it if it’s needed. That’s what judicious use means. If you don’t need it, don’t use it. If you don’t know why you’re treating it, or what you’re treating it for, don’t use it.” Some participants provided greater detail and specified that judicious use of antibiotics included avoiding blanket use and following directions regarding use. Blanket use of an antibiotic in livestock generally refers to administering an antibiotic to a group of animals for disease prevention or treatment, regardless of whether a specific individual is suspected to have a given disease. Other farmers’ descriptions incorporated prevention of disease, use of diagnostic tests, observing treatment effectiveness, using the least amount, and disease prevention. One participant associated the “judicious” with the consequences that they could face resulting from shipping a load of milk with antibiotic residues.Conventional farmers perceived their antibiotic use on dairy farms to be generally minimal, optimal, or improving. Several argued that further decreasing their antibiotic use would compromise animal welfare and/or cause them to cull more cattle.“You have to treat her. It’s no different than would you no give your kids antibiotics if they were sick? It’s not like we go around giving our kids antibiotics for no reason. Same with the cows, we don’t give them antibiotics for no reason. If they are sick they need to be treated.” Overall, participants indicated that they used antibiotics only when necessary, their level of use was low/minimal, and/or that they were considering using less. Some emphasized that they, as well as dairy farmers in general, prefer not to use antibiotics because of the many drawbacks of antibiotic use. Examples of drawbacks included the cost of the antibiotic itself, lost milk yield due to having to potentially discard milk from treated cows, and time spent managing treated cattle to prevent them or their products from entering the food supply.“Yeah. I try to tell people, when I get the opportunity, that I think the misconception that is out there is that we use antibiotics very frequently, and without merit, and that sort of thing. And I try to make them aware that we try to keep a very healthy animal so we don’t have to use antibiotics. Because antibiotics cost us money in lost product …” When asked about perceptions of other farmers’ antibiotic use practices, most participants stated either that they did not know about other’s practices or stated that dairy farm owners and/or managers prefer to use as little antibiotics as possible. While most dairy farmers believed that however, some participants, including those who reported that most dairy farmers preferred to not use antibiotics if they were not needed, stated that they knew of other farmers whose antibiotic use practices were not optimal due to overuse or failure to properly follow withhold times or directions on drug labels. In fact, one of this study’s participants suggested they administered a greater dose of antibiotic than recommended by the directions on the label if they felt they were treating a more serious illness because they believed it would help the animal recover faster.Theme 3: Herd health management was repeatedly emphasized as an effective preventive tool that could limit the need for antibiotics, but financial and other limitations impeded facility and other improvementsBoth organic and conventional farmers emphasized the importance of disease prevention and maintenance of herd health as opposed to treatment and believed that focusing on prevention lessened the need for antibiotic treatment.“I think the main impetus, and [the herd manager] certainly does this beautifully, is to keep the cows at a high plane of health so you don’t have to use antibiotics. That includes doing preventive inoculations, a clean place for them sleep, and excellent feed.” “I’m trying to find ways to use less [antibiotics]. I know other managers would like to use fewer antibiotics. The only way you are really going to do that is just through management, is through better prevention.” They described management or facility changes they hoped to make. Most changes were related to improvements in infrastructure and facilities, often with a focus on calf and dry cow facilities. Management changes included improved biosecurity, reducing overcrowding, and finding management strategies to prevent pneumonia in calves . For many farms, pathogen-based mastitis therapy was an important part of managing mastitis in cows. All farmers who spoke of this treatment strategy spoke positively of it, and some mentioned it had allowed them to operate more efficiently and reduce their antibiotic use.“Yeah, it’s that blanket treating everybody that didn’t do a damn thing, not in reality. Better off following [pathogen based mastitis therapy]—All the research and all the data has shown, this bacteria can be treated, this can’t be, and this is how you handle it. Use a lot less drugs and a lot less time out on the table too, cow individually.” Some farmers did mention that other farmers may face logistical barriers (transport of sample) or time/labor barriers to participation in the program.Facility changes included improving barn ventilation , building a new barn at a more convenient location, building a dry cow barn or improving an existing dry cow barn, having calving pens, having better calf facilities in general, transitioning to sand bedding for cows, having greater available acreage for cattle on pasture, and general facility renovations/upgrades. Some were also exploring new tools, such as rumination collars, they hoped to utilize in order to improve the health of their cattle. They expressed the sentiment that with greater resources, especially related to infrastructure/facilities, they could further improve the health of their cattle. Many also mentioned that there were a variety of ways in which farmers might improve herd health through management changes, but that those changes required commitment and tradeoffs.“If your focus, is, ‘We want to use less antibiotics,’ then there’s a hundred different ways to do it. Where it may cost more in labor, or management practices, or something like that. But if that’s the focus, I think any place, including us, can probably find different ways to do it to be able to reduce.” Theme 4: Organic farmers express more concern about antibiotic resistance and human health implications; both conventional and organic farmers support views on antibiotic use that are in line with their respective business practices Regulations for antibiotic use in organic farming differ starkly from those for conventional farming, namely that once treated with antibiotics, a cow’s milk can never be sold as organic again. Treatment, however, cannot be withheld from cattle requiring it. Organic participants' descriptions of judicious antibiotic use were more detailed than those of conventional participants and included that antibiotics should not be used to increase production (growth promotor or milk production enhancer), used for prevention, used as a blanket treatment, or fed in the form of medicated feeds.“I think only for therapy, for known extant medical issues. Not a routine blanket kind of use, just to prevent something that may never be a problem. And/or it should not be used as a growth promotant, or to increase production—either growth or milk production.” Others commented on concerns about antibiotic residues entering consumer products, despite regulations, practices and penalties designed to prevent this–but felt that pressure to be “pro all milk, not just organic milk” made this difficult to communicate . One organic participant responded differently to this inquiry about judicious antibiotic use by raising the concern that on organic farms antibiotic treatment may be delayed too long to maximize profit since animals treated with antibiotics lose value as they need to be sold to the non-organic market. In general, delayed treatment can result in poorer clinical outcomes and/or prolonged animal suffering.When discussing antibiotic resistance, in contrast to conventional participants, organic farmers had higher levels of concern about antibiotic resistance. They also often framed antibiotic resistance as a larger environmental and public health issue , rather“But I’m concerned for the health—for the human health side. That we don’t lose—that we as a people don’t lose effective use of antibiotics that are important to human treatment. As well as just all those antibiotics getting in the waterways. I mean not only from animals, but from all the pharmaceuticals from people too. But I mean, certainly if animals are routinely being treated, you know, it’s got to end up in the waterway sometime. Because I don’t think the body’s metabolizing it all or breaking it all down.” There was some similar doubt amongst organic farmers about the extent to which dairy farming was contributing to antibiotic resistance, particularly the human health impacts. One organic participant said that human health impacts of antibiotic resistance were primarily due to overprescribing in human medicine, not overuse in dairy farming.Theme 5: There was widespread concern about the impact of marketing and consumer perceptions on dairy; notably, many farmers believed that consumer misperceptions were driving regulationAll conventional farmers expressed concern about consumers’ lack of knowledge and/or misconceptions about the dairy industry, especially in regard to cattle welfare, and the impact of this misperception about antibiotics on both purchasing and regulation.“I think they [consumers] are under the impression that their milk comes from factory farms where the cow’s welfare isn’t taken into account. I’ve got relatives … that are just amazed at how well we treat the cows when they come see the farm. But before they were here, they were under a totally different impression. We got to make the public aware of what we do.” “I think it’s regulations and definitely something that’s consumer-driven—an awareness of consumers and what… the fact of the matter is that with consumers, perception is reality.” “Bottom line, the consumer is what drives everything and that’s why we do things the way we do. But because of uneducated people it makes it harder for us to do our job the way we should be able to do it.” Conventional farmers commented that antibiotic overuse is not as commonplace as consumers believe and that not using antibiotics when needed is inhumane and a welfare concern.“Well I still think that a lot of people think you can give a cow antibiotics and ship the milk. Obviously we can’t do that. So that’s something consumers should realize that… And I think it’s a good change what we’re going to, trying to minimize the amount of antibiotics we’re using. But in the same token, you know if your child has an ear infection and you know what antibiotic can cure it, you’re going to give it to them. You’re not going to say, “Oh, it’s antibiotic. No, stay away.” So I think in the right circumstances I mean it promotes health. Just don’t abuse it.” Further, they expressed concern about consumer worries about residues in the milk and emphasized the safety mechanisms that are in place to prevent consumer exposure to antibiotic residues in milk because of the withholding periods, testing, and high penalties for violation.“So, being that I grew up around animals and food operations, then I probably don’t have a lot of the misconceptions other people do. Like if a label says that it’s antibiotic free, it’s like, “Well of course it’s antibiotic free. Any milk you get’s going to be antibiotic free.” So, that’s sort of a misnomer. But, because it seems so natural to me like, that’s how it’s going to be, then I can’t understand how anybody would ever think any different.” “Some of them should know that every drop of milk that goes to a processing plant or a bottling plant is tested for antibiotics. There’s none in it. I think that’s the biggest misconception that consumers have, is that if they are not buying an organic product, then what they are buying has been laced with antibiotics in some form or other. They should know that that’s not the case. It’s all tested and that there’s nothing there. That is what I would like people to know.” Indeed, previous studies summarizing and investigating the presence of antibiotic residues in milk have found occurrence of residues to be low  31]. Ho. Ho31]. As previous quotes have hinted, conventional farmers are concerned about organic farming practices and the impact on consumer perceptions of organic dairy product marketing. Some conventional participants expressed disagreement with organic farming rules and requirements regarding antibiotic use. These participants are concerned that organic farming requirements create a financial incentive to not treat sick animals or to wait longer to treat, potentially compromising animal welfare.Conventional participants also mentioned that the organic designation is simply a marketing tool and meaningless in regard to milk quality.“I’m sorry, I’m totally against organic, so I think that’s just a whole foo-foo thing, because you’re just paying for… I mean, our ancestors lived hundreds of years and they didn’t have organic. I think it’s just a marketing push…” “… If I was talking to a consumer I’d say—if you go back to organics—I would say, “Why do you want to buy milk taken from a cow that’s sick? What is your reason for wanting this? Why do you want to spend another dollar or whatever for milk to drink it from a sick cow?” And I still don’t understand why people want to have it but apparently there’s demand for it. ….” Finally, several farmers expressed suspicion about whether organic farmers were fully following organic requirements. They suggested that organic farmers were actually using antibiotics in violation of organic requirements–treating sick cows and selling that milk as organic.Theme 6: Conventional farmers possess mixed views of current regulatory efforts to control antibiotic use and fear further restrictions on their antibiotic useParticipants reported that in general, government regulations (including the VFD) and rules established by milk cooperatives, buyers, and marketers have been workable and not overly burdensome to implement.“I don’t have a big problem with that [the VFD]. If you’re going to be using antibiotics, you should… your vet should be involved.” “Certainly, it makes us more—I think it just makes us more conscious of the use. So… I haven’t seen where that’s—I can’t see where that’s a bad thing. I mean, I guess a greater concern was if that sort of creep kept happening, where there are more and more restrictions. Which I guess is hard to say when it’s been too much. But it doesn’t really feel like it’s been stuff that’s been burdensome.” “Oh… Well… I’d say I don’t have a great opinion on it, other than it’s kind of cumbersome. . . . it’s doing what it intended and it’s limiting the amount of antibiotics in feed that you can use. So if that’s the goal, then it certainly is, I’m sure, working, because it’s more of a hassle now to get a script and write down the exact days and how much you’re doing it. So I think most farms have pretty much gotten away from it. Probably.” Overall, farmers had varying opinions of the VFD and its purpose; some viewed it as a promoting positive change while others thought it was unnecessary and just an additional requirement to be met that came with costs.“I don’t know negative or positive because it could make some farms do a better job. But it would make other farms that are doing a good job have to hire an extra person or two to fill in the gaps. I’ll spend two hours a week writing SOP’s and making sure people are up to date on what the guidelines say they are supposed to be doing. Where five years ago, I would just go out and talk to everybody and I wouldn’t have had to write everything down. I think in the future I’m just going to have to do more paperwork, which is going to take me away from being with the cows. So I’m going to have to hire a new half-a-person or a person that I wouldn’t have had to. It will be less efficient.” Some participants disliked rules and regulations because they viewed them as interference into their work and business.“I guess for me, I’ve gone from being just a farmer and doing the work to doing more labor management. … And environmental and other government—I call it intrusion—into our business. People say all these rules are good, but if you could keep the banker happy and the milk inspector happy when I started—that’s all you had to worry about. I didn’t have hired labor, so you didn’t have to keep your hired men happy, you didn’t have to keep the DEC [NYS Department of Environmental Conservation] happy, you didn’t have to keep the FDA happy… All these rules that are being imposed on us now, and public pressure. We try to do as good a job as we can, but all the scrutiny is kind of a challenge for me.” This farmer notes the conflict about the potential value of additional advice, but the potential loss of autonomy and the possibility for further restrictions on antibiotic use:“Yeah. So, I think I’m divided on it. Part of me thinks, again, having that extra conversation with a veterinarian that is prescribing these drugs is really important, because he needs to be conscious of how we’re using it, and that we’re not being irresponsible, using his name to use drugs that shouldn’t be used that way. So having his opinion one more time of, “Alright, well these calves should be treated,” or “these calves shouldn’t be treated,” is really good. But then, the libertarian in me says, “Hey, you know, how much more should people infringe on the way that we—the practices that we think are going to be the best for the calves.” So I’m just sort of evenly divided on the benefits of it, but then also that little of bit of a creep in of… Somebody coming in—between the relationship of us and our vet, that pushes us and wants to make those type of things more restricted. I can’t say that that’s a good thing or a bad thing, but I think it’s just a concern.” As alluded to in the last part of the above quote, a frequently mentioned concern was the possibility of further limitations on which antibiotics could be used or how much, and how much more difficult further restrictions would make their work without providing visible benefits.“I will tell you this, we don’t have very good luck treating pneumonia anymore. I think that’s because they’ve taken all the good antibiotics away from us. That’s one area that if we do get a developed cow with pneumonia, we just don’t have the arsenal of drugs in my mind to treat her the way she needs to be treated.” “I understand why they’re doing it, and I don’t disagree with it. It’s just… Some of it is, I guess the hardest part is, I understand why they’re doing it all, with antibiotics, but it’s getting down to the point where, pretty soon we’re not going to have a hell of a lot of choices. I just don’t it want it to hurt the animal…” Conventional dairy farmers’ general perceptions of antibiotic resistance expressed during these interviews reflect those described in previous literature, though our findings include stratification of farms by conventional versus organic status. Most conventional farmers in our study did not express concern about and/or belief in potential consequences of antibiotic use in dairy farming on human health, a finding consistent with other research on the topic  11] [34 [3411] . Or. Or34]. The interviews exposed tension between some conventional and organic farmers with regards to the use of antibiotics. Both sides believed their farming methods  were optimal and that they were ‘good farmers’. However, some conventional farmers expressed moral concern that reducing antibiotic use could potentially threaten cattle welfare and that welfare may be compromised on some organic farms if antibiotic treatment is delayed to maintain an animal’s organic status. In contrast, some organic farmers expressed concern about human health impacts of antibiotic use in cattle, drug residues in milk, and the environment, as well as that on some conventional farms antibiotics are used to compensate for not applying methods to prevent disease in the first place. These findings are not surprising given the literature about motivations for ‘good farming’ that differ between conventional and organic farmers. Conventional farmers seem to be motivated by proficiency and timelines  while foThe interviews highlighted the many stakeholders that dairy farmers must interact with and navigate among in the dairy industry. These include consumers, the government, and milk buyers. Farmers felt consumers were misinformed about various aspects of dairy farming, including antibiotic use. Consumers may indeed lack knowledge about dairy farming; in 2016, only 1.5% of the U.S. population was employed in the agriculture, forestry, fishing, and hunting sector . FurtherThis study provided new information about NYS dairy farmers’ perceptions of the new VFD. Participants expressed that it takes their additional time and effort to comply with the VFD rule. Some recognized its role in promoting more judicious antibiotic use. For example, it dissuaded some participants who were using medicated feed or milk replacer in their youngstock prior to the regulation to stop using it. Others thought the new rule was unjustified and taxing. These findings overlap with those from few existing studies about the VFD in the U.S. In Tennessee, dairy farmers perceived the VFD as unnecessary and burdensome, to have affected small producers, and introduced additional costs . AnotherTo help advance changes in antibiotic use, research indicates that dairy and other farmers generally prefer to receive antibiotic-related information from their veterinarians who they view as a trusted source of information  35] [50 [5035] . This isComplicating the relationship between conventional dairy farmers and stakeholders is the belief that the marketing of organic dairy products contributes to and reinforces consumers’ misconceptions about the dairy industry: specifically, that organic dairy farming is somehow “better”. While research does suggest that consumers may associate organic food with being healthier, free from antibiotics, hormones, and chemicals, and improved animal welfare  33], it, it33], It is important to consider the results presented here in the light of the intended scope of the study and limitations. The purposive convenience sample of farmers from NYS was not able or intended to be representative of all NYS dairy farms, much less all dairy farmers in the U.S. Study participants were selected from farmers participating in programs offered by Cornell’s QMPS, as this is how we had access to dairy farmers. This could have potentially introduced a selection bias into our study if farmers with particular characteristics had disproportionate representation or were not representative of the general population of NYS dairy farmers. There was no way for us to compare study participants in QMPS with non-participants, and there are issues therefore that may not have emerged. The study involved a relatively small sample size, especially of organic farmers. While we do not believe this compromised the richness of our data as we reached saturation, this study design did not intend to enable an exploration of potential differences between subgroups in our sample, such as large versus small farms within each category . The interview setting utilized in this study makes social desirability bias possible, due to the controversial nature of the conversation surrounding antibiotic resistance and appropriate use of antibiotics. While the veterinary student interviewer likely exerted some level of influence to report proper antibiotic use among dairy farmers, the participants may have been more forthcoming than had a veterinarian or dairy expert conducted the interviews. Our semi-structured questions did not explicitly distinguish between intramammary versus systemic antibiotic use, and therefore no differentiation could be made between antibiotics used for the treatment of mastitis versus systemic illnesses. Similarly, we did not explicitly question participants about the use of antibiotics for mastitis treatments and farmers’ opinions regarding current and emerging usage practices . Our findings are based on farmers’ perceptions and self-report of practices. The study was not designed to observe practices and animals in order to compare those observations to what was reported in interviews about behaviors around judicious use or animal welfare. The study findings are specific to NYS, so not all themes may be relevant to dairy operations in other areas of the US.To our knowledge, this study is unique in that it formally explored the NYS dairy farmers’ perceptions of antibiotic use in dairy cattle and antibiotic resistance. The results suggest perceptions held by farmers that may be targeted for additional research and educational interventions and suggest avenues through which educational communication might occur. Given farmers’ interest in disease prevention, they would likely be amenable to interventions focused on improving the efficiency and financial viability of their operation through improved herd health practices, including optimal antibiotic use/best practices. Such interventions would likely be best delivered by a veterinarian given farmers’ trust of them. Since veterinarians have an important role to play in promoting judicious antibiotic use practices, it is vital to acquire an understanding of their own perceptions of antibiotic resistance and their interest in promoting interventions among dairy farmers.Finally, having a way in which to quantify antibiotic use in order to better understand how judicious one’s use actually is would be valuable in an effort to promote judicious antibiotic use, as would establishing a consensus on what best practices are, given the variation. Adopting an inclusive and multidimensional approach to tackling antibiotic resistance that encourages interactions between veterinarians, medical professionals, public health professions, and farmers will help to ensure that proposed solutions are practical and amenable to all.S1 Appendix(DOCX)Click here for additional data file.S2 Appendix(DOCX)Click here for additional data file.S3 Appendix(DOCX)Click here for additional data file.


To improve the weak mechanical properties of the foamed concrete that resulted from a large number of pores, a plant fiber is used as fill with the matrix. In this study, five contents of sisal fiber are added into the foamed concrete to investigate the static and fatigue performance of composites. The static and fatigue experimental results show that the sisal fiber can improve the mechanical properties of the foamed concrete. When the content of sisal fiber is less than 0.15%, the higher the content of sisal fiber, the greater the bending strength and fatigue life of the foamed concrete. In contrast, if the sisal fiber content is larger than 0.15%, the bending strength and fatigue life decrease with the increasing fiber content. From the regression analyses, the results show that the double linear relationships exist not only between the sisal fiber content and the flexural strength, but also between the sisal fiber content and the fatigue life of the foamed concrete. In this study, the optimal content of sisal fiber mixed in the foamed concrete can be inferred to be 0.133%. For the excellent physical properties, the foamed concrete is extensively used in civil engineering. In 1923, a swede Axel Eriksson achieved the first patent related to the foamed concrete ). More aTikalsky P.J. et al.  develope3 and 0.6 kg/m3 to 1.2 kg/m3, it showed that the optimum content of fibers is 0.6 kg/mm3. When the content reaches 0.9 kg/m3 or more, the agglomeration of fibers will occur to decrease the mechanical properties. Further study was presented by Falliano D. et al. [fV) 2%, the flexural strength of composites will increase by 327%, 382%, 430%, and 485% for the polypropylene fibers, bare steel fibers, zinc-coated fibers, and brass-coated fibers . Mastal. et al.  compared. et al.  used uni. et al.  that it . et al.  selected. et al.  adopted . et al.  presente. et al.  further . et al.  studied . et al. ,24.The sisal fiber comes from the plant, with high environmental protection, easy degradation, low cost, adding it to the foamed concrete matrix to improve its flexural and fatigue performance, has important scientific significance and broad application prospects. In this study, the natural sisal fiber is used to improve mechanical properties of the foamed concrete. The task of the research is to find the effects of the sisal fiber on the static and fatigue performance of the foamed concrete. It includes three steps, the first is the static bending tests and then compressive tests will be carried out, from which the bending strength and the compressive strength can be gotten. The second, the fatigue performance tests of the concrete with five sisal fiber contents and the neat concrete are completed. Finally, the relationships between the fatigue life and the strain of, the fatigue equations of the composite will be conducted.To study the effects of the sisal fiber on mechanical properties of composites, the bending tests are divided into two parts. The first part is the static bending test and the second part is the bending fatigue test. The static bending tests include six groups, and each group has three specimens used to get the bending strength, from which the stress/loading levels of the fatigue tests can be determined. The first group of the static tests is used as reference group which has no any sisal fiber. In this group, the specimens are denoted as 0-1, 0-2, and 0-3. Except the first group, the other five groups contain five sisal fiber content of concretes, and the corresponding sisal fiber volume ratios are applied as 0.05%, 0.1%, 0.15%, 0.2%, and 0.3%. The numbers of all the static test specimens are listed in Similarly, the fatigue tests also include six groups, and each group chooses nine specimens to complete fatigue tests under three stress/loading levels of 0.75, 0.80, and 0.90. The numbers of the fatigue specimens are listed in In this study, the ordinary Portland cement labeled 42.5  is selected as the binding material. To improve the compactness of the concrete and save the cement, fly ash and the silica fume are also used. Silica fume has a smaller fineness, and the average particle size ranged from 0.1 to 0.3 microns, which acts as a good filling enhancement effect. The standard sand is selected as aggregate, and the water-binder ratio is taken as 0.45. To get the foamed concrete, hydrogen peroxide foaming agent (30 L) and calcium stearate foam stabilizer (2 kg) are used in tests, at the same time, water reducing agent is selected to increase the strength of the composites. The mix ratio of the neat foamed concrete is listed in Making the foam concrete includes the preparation of the mortar, configuration of the foam agent, mixing with sisal fiber and stirring and vibrating. In detail, firstly, the cement, standard sand, fly ash, and the silica fume are poured into the mortar mixer to stir for 1.5 min, and then, the different volume fraction sisal fibers are added into the matrix to stir for 2 min. After that, other materials, such as the hydrogen peroxide foaming agent are mixed in the compound slowly. All the materials are stirred for 3 min again to ensure they are well mixed.The static bending tests are carried out on the hydraulic universal testing machine WEW-300B  with the computer controlling. The distance of two support points is 200 mm, the strain gauges glued in the specimen are connected with the static resistance strain gauge. At the mid-span, three strain gauges are glued on the side of the beam to measure the strains of the upper, lower, and the neutral layer. The positions at the upper and the lower are close to the top and the bottom about 15 mm. At the same time, two strain gauges are glued at the positions close to the support points. The distances between the strain gauge and the support point or the bottom are also 15 mm. The force loading is applied as the loading mode and the loading rate is 0.02 kN/s.To conveniently compare the bending strength of the foamed concrete with different sisal fiber contents, all the testing results are listed in From the above testing data, it can be seen that the bending strength of composites added with different sisal fibers are higher than that of neat foamed concrete. On the other hand, because of the toughness of the sisal fiber, the ultimate strains of the sisal fiber reinforced the foamed concrete at the specified positions are also larger than that of the neat foamed concrete. The specified positions glued the strain gauges are located at the midspan of the beam and near the support point. If all the responding data with different sisal fiber contents are plotted in the diagrams, it is more convenient to compare the improvement of the sisal fiber on the bending performance of composites . tf is the bending strength and the C is the content of the sisal fiber.In order to find the optimal sisal fiber volume fraction, the bi-linear regression on the bending strengths of the specimens is carried out. From the first three points, the ascent line is fitted and can be extended over the horizontal coordinate of 0.10. Similarly, in terms of the last three points, the second fitting line can be gotten. The two fitting curves  can prodFrom the determination coefficients of the two fitting lines, the average value is obtained as 0.922, so the correlation coefficient can arrive at 0.960 which is close to 1.0. Thus, the optimal sisal fiber content obtained with this method is convincing.Pu can be used to determine the stress levels for fatigue tests. Three stress/loading levels (SR = Pmax/Pu) of 0.75, 0.80, and 0.90 are selected, the loading forces are gotten from the bending strength . Experimental data such as maximum and minimum load, mid-span displacement of the specimen, loading cycle number (fatigue life) For each stress level and each sisal fiber content, there are three specimens are tested. In order to compare these test results conveniently, all the data are plotted in In order to get the relationship between the strains and the fatigue lives of the specimens, the tensile strains at the middle of the beam (Tensile position 1) and the tensile strains at one side close to the support point (Tensile position 2) are as samples to be discussed. The tensile strain–fatigue life curves with no sisal fiber are plotted in When the content of the sisal fiber is taken as 0.05% and the stress level is 0.75, the strain data are plotted in με and far greater than the value 81 με of the neat foamed concrete. When the sisal fiber volume fraction continues to increase, the fatigue life of composite and the ultimate tensile strain at the position 1 decrease slightly. This case is caused by the agglomeration of sisal fibers. For position 2, close to the support point, the similar improvements of sisal fibers on the tensile strain and the fatigue lives of the composites are plotted in Because the foamed concrete has many voids and micro-cracks, it has the low density and low strength. When the sisal fibers are added into the matrix, the sisal fiber can play a bridging role to resist the deformation of the composites if the cracks grow under the external force. This means that the sisal fiber can absorb more energy as the composites break. In order to compare the strain increasing trend and the effects of resisting crack propagation, the tensile strain–fatigue life curves with the different volume fraction of sisal fibers are placed into one figure. Under the stress level of 0.75, the tensile strain curves with varied sisal fiber content at the position 1 are plotted in με, 2.3 times the value 79 με of the neat foamed concrete. Correspondingly, the fatigue life of the composite is 2.98 times that of the neat foamed concrete  SR–N curves shown in SR = 0.75, 0.80, 0.90), the fatigue lives of all specimens are lower. Although the experimental data are limited, the trend of SR–N curves is still obvious. In general, with the stress level decreasing, the fatigue life of the composite will increase. Within the scope of the experiments in this study, when the content of sisal fiber is less than 0.15%, the fatigue lives of the composite increase with the increase of fiber content, as shown in According to the fatigue experimental data shown in S–N curve, Basquin equation, power function Equation, exponential function Equation, etc. In this study, with the limit experimental data, the following empirical Equation is used to fit the S–N curves.A and B are constant.For the fatigue failure of materials, because of the huge discreteness, many experiential methods are applied to analyses, such as SR–N curve, the constants A and B of each equation can be obtained, as shown in By using Equation (2), the least square method is used to fit the experimental data for each (2) Effect of Sisal Fiber ContentIn order to discuss the effect of sisal fiber content on the fatigue performance of the composite, the average fatigue life data of various fiber content are listed in N (cycles), and sisal fiber content, C (%), are obtained as follows:N0 (cycles) and NC (cycles) are the fatigue lives of the concrete with no sisal fiber and that with sisal fiber content by CC = 0.133%, respectively, and p and q are constant.For each stress/loading level, the least square method is used to fit the experimental data, the bilinear equations for the relationships between fatigue life, p, q, N0, and NC can be obtained by fitting the data of the average fatigue lives and sisal fiber contents for each stress/loading level SR, and as shown in The Parameters To enhance the low strength and the low toughness of the foamed concrete, sisal fibers with five contents of 0.05%, 0.10%, 0.15%, 0.20%, and 0.30% have been added into the matrix to strengthen the mechanical properties of the foamed concrete. With the static bending tests and fatigue tests, the experimental data show that the sisal fiber can improve the mechanical properties of the foamed concrete if the sisal fibers are homogeneously dispersed in the matrix. The main results are as follows:(1) The experimental results of sisal fiber reinforced foam concrete under static bending load show that there is a double linear relationship between the content of sisal fiber and the flexural strength of the concrete. The optimal content of sisal fiber in the foamed concrete in this study can be inferred to be 0.133%.(2) Fatigue test results show that sisal fiber can increase the fatigue life of the foamed concrete. When the content of sisal fiber is less than 0.15%, the higher the sisal fiber content, the larger the strength of the concrete. If the content of sisal fiber is greater than 0.15%, the fatigue life of the foamed concrete will decrease with the sisal fiber content increasing.(3) For each stress level, 0.75, 0.8 or 0.9, the relationship between the fatigue life of foam concrete and sisal fiber content is efficiently analyzed by bi-linear regression. Furthermore, the bi-linear function is the same as that used to depict the relationship between the static flexural strength and the sisal fiber content. Thus, to improve the fatigue life of foam concrete, the optimal sisal fiber volume fraction is also 0.133%.


Inappropriate antibiotic utilization is associated with the emergence of antimicrobial resistance (AMR) and a decline in antibiotic susceptibility in many pathogenic organisms isolated in intensive care units. Antibiotic stewardship programs (ASPs) have been recommended as a strategy to reduce and delay the impact of AMR. A crucial step in ASPs is understanding antibiotic utilization practices and quantifying the problem of inappropriate antibiotic use to support a targeted solution. We aim to characterize antibiotic utilization and determine the appropriateness of antibiotic prescription in a tertiary care pediatric intensive care unit.A retrospective cohort study was conducted at King Abdullah Specialized Children’s Hospital, Riyadh, Saudi Arabia, over a 6-month period. Days of therapy (DOT) and DOT per 1000 patient-days were used as measures of antibiotic consumption. The appropriateness of antibiotic use was assessed by two independent pediatric infectious disease physicians based on the Centers for Disease Control and Prevention 12-step Campaign to prevent antimicrobial resistance among hospitalized children.During the study period, 497 patients were admitted to the PICU, accounting for 3009 patient-days. A total of 274 antibiotic courses were administered over 2553 antibiotic days. Forty-eight percent of antibiotic courses were found to be nonadherent to at least 1 CDC step. The top reasons were inappropriate antibiotic choice  and inappropriate prophylaxis durations. Cefazolin and vancomycin contributed to the highest percentage of inappropriate DOTs.Antibiotic consumption was high with significant inappropriate utilization. These data could inform decision-making in antimicrobial stewardship programs and strategies. The CDC steps provide a more objective tool and limit biases when assessing antibiotic appropriateness Antibiotics are the most common medications prescribed in pediatric intensive care units (PICUs), with up to 50–100% of patients receiving an antibiotic prescription –8. HowevAntimicrobial stewardship programs (ASPs) are recommended to decrease inappropriate antibiotic use and mitigate its effects , 20. ThiThis retrospective cohort study was conducted at King Abdullah Specialized Children’s Hospital (KASCH), an academic tertiary center in Riyadh, Saudi Arabia with a current capacity of 220 beds. The hospital has a 25-bed closed medical and surgical PICU admitting approximately 1000 patients per year. At the time of this study, there were no approved local antimicrobial guidelines, and no antibiotic stewardship program or strategies were implemented.A retrospective cohort study was conducted from January to June 2017 (6 months). The Institutional Review Board (IRB) at King Abdullah International Medical Research Center (KAIMRC) approved the study, and the requirement for informed consent was waived.All pediatric patients aged 0–14 years who were admitted to the PICU and started on antibiotics during the study period were included. Patients were excluded from the study if they were > 14 years of age, or were known to have an immunocompromising condition , or on immune-compromising medications, or only requiring antifungal or antiviral agents.Data from electronic medical records were collected using a standardized form and reviewed by two pediatric infectious disease physicians in the study group. Data collected included patient demographics, disease comorbidities, admitting and/or infectious diagnoses, admission type , indication for antibiotics, documentation of antibiotic indication in medical chart, microbiological results on documented infections, consultation of infectious disease (ID) services, and antibiotic utilization (type and duration). Identified infections were reviewed, and multidrug-resistant organisms (MDROs) were identified based on susceptibility patterns and resistance to most available antibiotics.Antibiotic indications were classified as empiric , definitive , or prophylactic  , 23. ForThe appropriateness of antibiotic use was independently assessed by two pediatric ID physicians. Consensus agreement was sought in more complex cases and when opinions differed. Appropriateness was based on clinical judgment and classified using the CDC 12-step Campaign to prevent antimicrobial resistance among hospitalized children . The CDCDays of therapy (DOT) per 1000 patient-days was used to quantify antibiotic consumption. DOT was defined as the number of days that a patient received antibiotics regardless of the dose. When a patient received more than one antibiotic simultaneously, one DOT was counted for every antibiotic given . PatientIBM SPSS version 26 was used to analyze the data. The median and percentile (25th–75th) were used to describe quantitative variables, such as age and duration of antibiotic courses. Frequencies and percentages were used to describe qualitative variables, such as gender, admission type, and indication for antibiotics. Comparisons between appropriate and inappropriate antibiotic courses were performed using Fisher’s exact test for categorical data and Mann–Whitney U test for continuous data. A P-value < 0.05 was considered statistically significant for all analyses.During the study period, 497 patients were admitted to the PICU, accounting for 3009 patient days. After excluding 238 patients based on the study criteria, 259 patients were included in the review. Table Overall, 259 children received 274 antibiotic courses, resulting in 2553 DOTs. The median duration of an antibiotic course was 8 days . The reason for antibiotic initiation was empiric in 187 courses (68.2%), prophylactic in 61 courses (22.3%), and definitive in 26 courses (9.5%). The most common clinical indications for antibiotic initiation were community-acquired pneumonia (19.3%), hospital-acquired sepsis (10.6%), community-acquired sepsis (9.9%) and bronchiolitis (9.5%).Compared to appropriate antibiotic courses, inappropriate courses were more likely in surgical admissions and in patients receiving antibiotics prophylactically (P < 0.05). A higher proportion of inappropriate courses occurred in patients receiving antibiotics post CNS procedures (P = 0.001). The duration of antibiotic courses was significantly higher in children with inappropriate antibiotic use than in children who had appropriate antibiotic use . For empiric antibiotics, no action taken at 72 h was associated with a higher percentage of inappropriate antibiotic courses, 20.8% versus 9.1% (P = 0.031).Table Figure The main objectives of this study were to describe antibiotic consumption in our setting, investigate appropriateness of antibiotic utilization by assessing adherence to the CDC’s 12-steps and uncover factors associated with inappropriate antibiotic utilization. The findings suggest a high percentage of inappropriate antibiotics courses. The most common violated CDC steps were “target the pathogen” and “practice antimicrobial control”. There was a higher percentage of inappropriate courses in surgical admissions and with prophylactic courses. Cefazolin and vancomycin had the highest number of inappropriate DOTs.Total antibiotic consumption was 848.5 DOTs per 1000 patient days, indicating a rising increment from 708.3 DOTs per 1000 patient-days previously reported between 2012 and 2015 . This diThe most common reason for non-adherence was violation of step 6 (target the pathogen) or step 4 . Nonadherence to step 4 includes inappropriate empiric or definitive antibiotic choices. Improving empirical and definitive choices would require a better understanding of common pathogens and local susceptibility patterns, and better utilization of diagnostics, in addition to reassessment and taking action after 72 h of antibiotic initiation. Within our cohort, for empiric antibiotics, a lack of action taken at 72 h was associated with a higher percentage of inappropriate antibiotic use (P = 0.031). In view of this finding, conducting an antibiotic ‘time-out’ would be a suitable and effective intervention . A time-Nonadherence to step 6 suggests an inappropriate prophylactic choice or duration, inappropriate antibiotic combinations, or route of administration. In our cohort 45 out of 61 (74%) prophylactic courses were deemed inappropriate. This may explain why the percentage of inappropriate antibiotics was higher in surgical patients (P < 0.001). Unnecessary prolongation of prophylactic treatment for specific procedures or for the presence of drains may be a contributing factor. Guidelines for perioperative prophylaxis recommend durations not extending beyond 24 h from initiation irrespective of the surgical procedure or the presence of drains or catheters , 23.It is noted that nonadherence to a combination of the CDC steps, and in particular combinations including steps 4, 9, and 10 have contributed to 30.7% of inappropriate DOTs. These steps are related to empiric and definitive antibiotic choices, durations, and avoiding the unnecessary use of broad spectrum agents. Antibiotic treatment decisions in intensive care are challenging and influenced by a difficulty to differentiate between bacterial and viral infections, a lack of gold standard to diagnose pneumonia and an uncertainty in sepsis etiology –32; for Staphylococcus aureus (MRSA) [Cefazolin and vancomycin contributed to one third of inappropriate antibiotic utilization . The finding that cefazolin had the highest inappropriate utilization supports the finding that CDC step 6 was the most violated step in nonadherent courses and that a higher percentage of inappropriate courses were seen in surgical patients, as it is the drug of choice for peri-operative prophylaxis. Inappropriate vancomycin utilization in our centre corresponds with studies in both adult and pediatric critical care settings , 36. Vans (MRSA) , 38. Sevs (MRSA) . Automats (MRSA) , 35.This study has several limitations. First, data were collected retrospectively; thus, some information influencing decision making could have been missed. Second, this is a single center report, which limits its generalizability. Third, decisions regarding antibiotic appropriateness are prone to bias, despite assessing the appropriateness in this study by two independent infectious disease physicians based on the unified CDC 12 step classification. Additionally, due to the retrospective nature of the study, the accuracy of diagnoses was not confirmed, and the authors accepted all diagnoses made by treating physicians. This meant that we could not assess nonadherence to step 8 (treat infection but not contamination or colonization).We were able to confirm a high prevalence of antibacterial utilization in the PICU with evidence of inappropriate prescription practices, mainly due to inappropriate perioperative prophylaxis durations and inappropriate empiric and definitive antibiotic choices. Based on our findings, the main areas for stewardship interventions include the development of empiric antibiotic guidelines (addresses step 4 and 9), re-education on surgical prophylaxis guidelines (addresses step 6), and the introduction of ‘time-out’ moments post-antibiotic initiation for empiric antibiotics (addresses step 10). Different approaches to antimicrobial stewardship need to be individualized based on identified concerns. Decisions regarding the appropriateness of antibiotic use could be facilitated by the development of local antibiotic guidelines and the utilization of tools such as the CDC steps to both standardize the process and limit bias and subjectivity.