In-line Filter Research Articles

Implementation Methods for Transmission Zeros in Groove Gap Waveguide Filters at W-Band

In this paper, three groove gap waveguide (GGW) filters are presented, which utilize different techniques to create transmission zeros (TZs) in the W-band. First, a fourth-order filter with cross-coupling of non-adjacent cavities realizes five TZs. The filter is implemented using a stacked cavity approach, which simplifies the realization of cross-couplings with positive and negative signs. The source to load cross-coupling realizes one TZ more than predicted from theory. In the second filter, two off-centered posts with partial height are used to realize two TZs. These posts act as strongly frequency-dependent coupling elements and enable the realization of TZs in an inline filter topology. An interdigital-pin implementation has been used since otherwise, the distance between the posts and the sidewalls is too small to allow manufacturing using the Computerized Numerical Control (CNC) milling approach. The third filter is of fourth order and implements two TZs by using a stub-loaded cavity approach. All filters are designed as a proof of concept in the W-band (75–110 GHz) to verify the manufacturability at high-frequency bands. The manufactured components are realized by high-precision CNC milling and measurement results show good agreement with the simulation for all proposed filters.

Fluid mechanical evaluation of in-line filter for fluid-handling systems by means of computational fluid dynamics (CFD)

Abstract Administering fluids and drugs intravenously is crucial in caring for vulnerable patient cohorts such as critically ill patients as well as neonatal and paediatrics patient populations. Studies have revealed severe contamination of infusion solution that could be avoided by utilizing in-line filters. The filtration performance consequently depends on the geometry of the filter housing. The purpose of our numerical study was to analyse the flow situation in filter housings depending on the geometry (diameter of the filter housing and distance between entrance and membrane). We compared the flow of two circular filter system with different housing width (D = 25 mm; L = 1.5 mm/3.0 mm) by means of computational fluid dynamics (CFD). The filter membrane was modelled by a porous jump condition. Both filter systems showed a highly reduced inflow on the membrane compared to the velocity in the Luer Lock ports. The wide filter housing facilitates a more homogenous inflow on the membrane (>92% of the membrane area is applied within a range of 5% of the mean velocity) compared to the narrow filter housing. Despite that difference both filter housings induced a well distributed flow through the filter membrane. However, for large filter systems (>50 mm diameter) the design of the filter housing could play a crucial role in optimising filter performance and therefore CFD should be considered.

Design of the inline filter with improved box-section topology based on dual-mode waveguide loaded air slots resonator

Design of the inline filter with improved box-section topology based on dual-mode waveguide loaded air slots resonator

Effect of in-line filtration in newborns: study protocol of the Intravenous Neonatal Central Access Safety (INCAS) randomized controlled trial

BackgroundParticulate contamination due to infusion therapy (administration of parenteral nutrition and medications) carries a potential health risk for infants in neonatal intensive care units (NICUs). This particulate consists of metals, drug crystals, glass fragments, or cotton fibers and can be generated by drug packaging, incomplete reconstitution, and chemical incompatibilities. In-line filters have been shown to remove micro-organisms, endotoxin, air, and particles in critically ill adults and older infants, but its benefits in newborn remain to be demonstrated. Moreover, 50% of inflammatory episodes in the setting of NICUs are blood culture-negative. These episodes could be partly related to the presence of particles in the infusion lines.MethodsA multicenter randomized single-blind controlled trial was designed. All infants admitted to NICUs for which prolonged infusion therapy is expected will be enrolled in the study and randomized to the Filter or Control arm. All patients will be monitored until discharge, and data will be analyzed according to a “full analysis set.” The primary outcome is the frequency of patients with at least one sepsis-like event, defined by any association of suspected sepsis symptoms with a level of c-reactive protein (CRP) > 5 mg/L in a negative-culture contest. The frequency of sepsis, phlebitis, luminal obstruction, and the duration of mechanical ventilation and of catheter days will be evaluated as secondary outcomes. The sample size was calculated at 368 patients per arm.DiscussionThis is the first multicenter randomized control trial that compares in-line filtration of parenteral nutrition and other intravenous drugs to infusion without filters. Sepsis-like events are commonly diagnosed in clinical practice and are more frequent than sepsis in a positive culture contest. The risk of these episodes in the target population is estimated at 30–35%, but this data is not confirmed in the literature. If the use of in-line filters results in a significant decrease in sepsis-like events and/or in any other complications, the use of in-line filters in all intravenous administration systems may be recommended in NICUs.Trial registrationClinicalTrials.gov, NCT05537389, registered on 12 September 2022 (https://classic.clinicaltrials.gov/ct2/show/results/NCT05537389?view=results).

Spallation and particles infusion into the extracorporeal circuit during CRRT: a preventable phenomenon

Patients in intensive care are exposed to the risk of microparticle infusion via extracorporeal lines and the resulting complications. A possible source of microparticle release could be the extracorporeal circuit used in blood purification techniques, such as continuous renal replacement therapy (CRRT). Disposable components of CRRT circuits, such as replacement bags and circuit tubing, might release microparticles such as salt crystals produced by precipitation in replacement bags and plastic microparticles produced by spallation. In-line filtration has proven effective in retaining microparticles both in in-vitro and in-vivo studies. In our study, we performed an in-vitro model of CRRT-treatment with the aim of detecting the microparticles produced and released into the circuit by means of a qualitative and quantitative analysis, after sampling the replacement and patient lines straddling a series of in-line filters. Working pressures and flows were monitored during the experiment. This study showed that microparticles are indeed produced and released into the CRRT circuit. The inclusion of in-line filters in the replacement lines allows to reduce the burden of microparticles infused into the bloodstream during extracorporeal treatments, reducing the concentration of microparticles from 14 mg/mL pre in-line filter to 11 mg/mL post in-line filter. Particle infusion and related damage must be counted among the pathophysiological mechanisms supporting iatrogenic damage due to artificial cross-talk between organs during CRRT applied to critically ill patients. This damage can be reduced by using in-line filters in the extracorporeal circuit.

Switching and transformation of multi-state solitons in a slightly normal dispersion mode-locked fiber laser

Passively mode locked fiber lasers are excellent platforms for soliton generation. Here, multi-state switchable behaviors in a slightly normal dispersion mode-locked fiber laser are experimentally demonstrated with an identical configuration. A saturable absorber based on single-wall carbon nanotube is served as mode-locking device and an intrinsic birefringence spectral filtering is employed as a tunable inline filter. Consequently, with properly modifying pumping powers and orientations of polarization controller paddles, the operation regimes of the proposed laser could be reversibly switched between dissipative solitons and amplifier similaritons, and the characteristics of intermediate states are recorded. Tunable dissipative solitons with a tuning range of 38 nm and noise-like pulses could also alternatively be generated. This multi-state behavior switching could be attributed to the strong filtering caused by the limited gain bandwidth under strong pump strength. The experimental observations of these multi-state switchable transitions may offer insight into the pulse regime dynamics in the near-zero dispersion region and offer flexibility in multi-functional designs of the laser configuration, which would enable innovations in nonlinear optics and its applications.

Synthesis Design of In-Line Pseudoelliptic SISL Bandpass Filter Employing Non-Resonating Mode in Low-Loss Patch Resonators

This paper presents a novel type of patch resonator suitable for the design of high selectivity in-line pseudoelliptic bandpass filters (BPFs) based on a substrate-integrated suspended line (SISL) platform. The proposed structure is a rectangular patch resonator that allows the propagation of the fundamental mode and high order modes. By controlling the position of input and output feedlines, the proposed resonators can provide both a reflection and a transmission zero simultaneously. Thus, a pole-zero pair can be produced (behaving as a singlet). The position of poles and zeros can be fully controlled by varying the position and orientation of the feeding lines. To verify the proposed concept, a detailed study about the behavior of the patch singlet and a validated third-order filter BPF with three TZs ( canonical BPF) located in the lower and upper passband is presented in this brief. The measured results exhibit an extended stopband with rejection better than 58 dB in the lower passband and 40 dB in the upper passband. The tested return losses and insertion loss are better than -15.7 dB and 1.31 dB, respectively.

Soft magnetic properties of Fe-Ni powder cores in the high frequency range

Fe-Ni cores are excellent candidates for switching regulator inductors, transformers, reactors and in-line noise filters. Herein the influence of the phenol binder content on the microstructure and magnetic properties of Fe-50 wt% Ni powder cores in the high frequency range is investigated. Regardless of the binder content, all cores form a disordered A1 phase. The saturation magnetization (4πMs) and initial permeability increase as the binder content decreases. The core with a binder content of 0.5 wt% shows a relatively high 4πMs of 1.38 T and the highest permeability value of 70.9. Moreover, the total core loss (Pcv) with frequency ranges from 5 kHz to 1 MHz under a magnetic flux density of 10 mT depending on the binder content. A binder content of 3.0 wt% significantly reduces Pcv in the high frequency range above 100 kHz. At a frequency of 500 kHz, the Pcv values are 154.9, 128.7, and 133.8 kW/m3 for the cores with binder contents of 0.3, 0.5, and 1.0 wt%, respectively, but the value drastically decreases to 60.5 kW/m3 for a binder content of 3.0 wt%. Thus, the binder, which acts as an insulator layer between particles, affects the eddy current and consequently, Pcv. These results demonstrate that Fe-Ni powder cores exhibit excellent soft magnetic properties at various frequencies and suggest that a binder content of 3.0 wt% may realize optimal properties for future high frequency applications.

Multidisciplinary Approach to Deciphering Etoposide Infusion Reactions and Potential Role of Polyethersulfone Filter Membranes.

Etoposide, a topoisomerase II inhibitor used clinically to treat cancer, has been associated with severe anaphylactic infusion related adverse drug reactions (ADRs). In a previous study we identified a hydrophilic polyethersulfone filter as a possible cause of increased rates of pediatric etoposide infusion reactions. In this multidisciplinary follow-up analytical study, we aimed to assess the chemical structure of etoposide after passing through the same hydrophilic polyethersulfone filter. An etoposide 0.4 mg/mL infusion was prepared under aseptic conditions and then passed through a standard IV infusion set with an in-line filter in place. Samples were taken in triplicate using a needle-less access system to include sampling sites directly from the IV bag port and from the IV tubing both before and after the in-line filter. Samples were diluted into mobile phase, then an aliquot was injected into a high-performance liquid chromatography mass spectrometry HPLC-MS (Thermo TSQ Quantum Ultra) system coupled to a Diode Array Detector (DAD) (Thermo Dionex Ultimate 3000). Etoposide was monitored using a selected reaction monitoring scan (SRM) of 606.2/228.8 and wavelengths of 210, 220, 254, and 280 nm for 30 minutes. No detectable differences were observed upon comparing the three samples. Based on these results, a chemical change in etoposide resulting from an in-line filter is unlikely to be the primary cause of increased rates of infusion reactions. Pharmacists working in healthcare systems, observe many ADRs, but rarely have the resources necessary to investigate the potential etiology or causality. This report highlights importance of multi-disciplinary collaboration to investigate serious ADRs.

The Singlet: Direct Synthesis of Pseudo-Elliptic Inline Filters With Frequency Variant Couplings

A general and direct synthesis of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N_{p}$</tex-math> </inline-formula> poles pseudo-elliptic inline filters having <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N_{p}$</tex-math> </inline-formula> purely real and/or imaginary frequency transmission zeros is presented. Using an appropriate model of the resonators (bandpass distributed or lumped element) and shifting the reference planes at the input and output of the filter network, a novel direct synthesis and realization of filters based on frequency variant coupling (inductive or capacitive) in the distributed domain is demonstrated for accurate modeling of narrow and broadband filters. First, a complete general synthesis procedure is described that allows for flexible or mixed topologies realizing transmission zeros anywhere on the frequency plane (including complex and infinite frequencies). Furthermore, by exploiting the power of modular design, a synthesis procedure that enables simultaneous extraction of reflection zero (a pole) and a transmission zero in the form of a symmetrical and physically realizable singlet as an elementary unit is showcased. The physical dimensions of the extracted singlets are independently determined in any chosen technology, and the overall filter is obtained by directly cascading the physical singlets. To validate this novel synthesis technique, three design examples are shown: a narrowband four-pole, four transmission zeros (fully canonical) filter from literature is synthesized and physically dimensioned, a wideband three-pole, three transmission zero (fully canonical) filter, and a broadband three-pole, one transmission zero, filter. In the first two examples, each of the singlet blocks was implemented in an overmoded rectangular waveguide cavity operating at the TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{201}$</tex-math> </inline-formula> mode coupled at the input and output to the fundamental nonresonating TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{10}$</tex-math> </inline-formula> mode. The third example was implemented in a re-entrant coaxial resonator operating at the fundamental mode. The simulation of the electromagnetic (EM) high-frequency structure simulator (HFSS) models of the overall example filters was in excellent agreement with the synthesized models, thereby validating the effectiveness of the proposed synthesis technique. Furthermore, the measured results of the fabricated wide bandpass filter showed close agreement with synthesis and EM model.

Alleviation of the necessity for supernatant prefiltering in the protein a recovery of Monoclonal antibodies from Chinese hamster ovary cell cultures

Protein A (ProA) chromatography is a mainstay in the analytical and preparative scale isolation/purification of monoclonal antibodies (mAbs). One area of interest is continuous processing or continuous chromatography, where ProA chromatography is used in the large-scale purification of mAbs. However, filtration is required prior to all ProA isolations to remove large particulates in cell culture supernatant, consisting of a mixture of cell debris, host cell contaminants, media components, etc. Currently, in-line filters are used to remove particles in the supernatant, requiring replacement over time due to fouling; regardless of the scale. Here we demonstrate the ProA isolation of unfiltered Chinese hamster ovary (CHO) cell media using capillary-channel polymer (C-CP) fiber stationary phases modified with S. aureus Protein A (rSPA). The base polymer of the analytical scale C-CP columns costs ∼$5 per 30 cm column, and when modified with ProA, the base cost is ∼$25 per 30 cm column, a cost-effective option in comparison to analytical-scale commercial columns. To directly sample unfiltered media, a 5 cm gap was created at the head of the C-CP column, where the large particulates are trapped, while molecular solutes flow through the capillary channels without sacrifice in analytical performance, mAb loading capacity, or backpressure increases. The binding capacity of the gap ProA C-CP column was ∼ 2 mg mL−1 of IgG per bed volume. The same analytical column could be operated after processing a total of ∼ 56 column bed volumes of supernatant (>25 analytical cycles) without the need for caustic clean-in-place processing.

Lack of effect of an in-line filter on cardiopulmonary exercise testing variables in healthy subjects.

Pathogen transmission during cardio-pulmonary exercise testing (CPET) is caused by carrier aerosols generated during respiration. Ten healthy volunteers (age range: 34 ± 15; 4 females) were recruited to see if the physiological reactions to ramp-incremental CPET on a cycle ergometer were affected using an in-line filter placed between the mouthpiece and the flow sensor. The tests were in random order with or without an in-line bacterial/viral spirometer filter. The work rate aligned, time interpolated 10s bin data were compared throughout the exercise period. From rest to peak exercise, filter use increased only minute ventilation ([Formula: see text]E) (Δ[Formula: see text]E = 1.56 ± 0.70L/min, P < 0.001) and tidal volume (VT) (ΔVT = 0.10 ± 0.11L, P = 0.014). Over the entire test, the slope of the residuals for [Formula: see text]CO2 was positive (0.035 ± 0.041 (ΔL/L), P = 0.027). During a ramp-incremental CPET in healthy subjects, an in-line filter increased [Formula: see text]E and VT but not metabolic rate. In conclusion, using an in-line filter is feasible, does not affect appreciably the physiological variables, and may mitigate risk of aerosol dispersion during CPET.

Evaluation of Strategies for Reducing Vancomycin-Piperacillin/Tazobactam Incompatibility.

Drug incompatibility is defined as a physical-chemical reaction between two or more injectable drugs and that results mainly in precipitation or insolubility. Several strategies for reducing incompatibilities have been implemented empirically in intensive care units. However, these strategies have never been compared directly (and particularly in terms of the particulate load and drug mass flow rate) under standardized conditions. The objective of the present in vitro study was to evaluate the impact of various strategies for preventing incompatibility between simultaneously infused vancomycin and piperacillin/tazobactam. An in-line filter, a dilute vancomycin solution (5 mg/mL), and an alternative saline administration line were evaluated separately. The infusion line outlet was connected to a dynamic particle counter. The antibiotic concentration was measured in an HPLC-UV assay. The use of an in-line filter and an alternative saline administration route did not significantly reduce the particulate load caused by vancomycin-piperacillin/tazobactam incompatibility. Dilution of the vancomycin solution was associated with a significantly lower particulate load and maintenance of the vancomycin mass flow rate. It is important to systematically compare the efficacy of strategies for preventing drug incompatibility. The use of diluted vancomycin solution gave the best results in the case of vancomycin-piperacillin/tazobactam incompatibility.

Poster 114: Viability and Expression of Chondrocytes Harvested During Arthroscopic Treatment of Femoroacetabular Impingement

Poster 114: Viability and Expression of Chondrocytes Harvested During Arthroscopic Treatment of Femoroacetabular Impingement

Comparative study between a gravity-based and peristaltic pump for intravenous infusion with respect to the generation of proteinaceous microparticles

Subvisible particles generated during the preparation or administration of biopharmaceuticals might increase the risk of immunogenicity, inflammation, or organ dysfunction. To investigate the impact of an infusion system on the level of subvisible particles, we compared two types of infusion sets based on peristaltic movement (Medifusion DI-2000 pump) and a gravity-based infusion system (Accu-Drip) using intravenous immunoglobulin (IVIG) as a model drug. The peristaltic pump was found to be more susceptible to particle generation compared to the gravity infusion set owing to the stress generated due to constant peristaltic motion. Moreover, the 5-µm in-line filter integrated into the tubing of the gravity-based infusion set further contributed to the reduction of particles mostly in the range ≥ 10 µm. Furthermore, the filter was also able to maintain the particle level even after the pre-exposure of samples to silicone oil-lubricated syringes, drop shock, or agitation. Overall, this study suggests the need for the selection of an appropriate infusion set equipped with an in-line filter based on the sensitivity of the product.

Inline Box-Like Dielectric Filters With Asymmetric and Symmetric Responses

In this article, a new class of inline filters with box-like properties and pseudoelliptic responses are presented. The proposed filters employ dual-ridge dual-mode resonators (DRDMRs). Each DRDMR can be used in modular filter design as a basic building block, which provides two poles and a transmission zero (TZ). Asymmetric and symmetric filtering responses can be obtained by simply changing the resonant frequencies of the DRDMRs while all coupling coefficients remain unchanged in both values and signs. By properly arranging the position of the coaxial feeding probe, the input–output coupling of the two resonant modes can be controlled flexibly and thus control the TZ position. Intracavity coupling is realized by the all-iris structure of the dual-mode form. To validate the feasibility, an inline fourth-order filter with a pair of symmetric TZs has been designed and manufactured. The experimental result agrees well with the simulated result.

Investigation of in-line filter replacement intervals for infusion

In-line filters in peripheral and central venous catheters are used to mechanically remove bacterial cells. A recent study indicated the extension of the use of infusion sets to seven days. There is no evidence regarding replacement intervals for in-line filters. We tested in-line filters that were continuously used for seven days for ability to remove bacteria as well as flow rate. Three different in-line filters were attached to an ELNEOPA-NF No.2® premixed infusion bag of intravenous hyperalimentation, into which Staphylococcus epidermidis ATCC12228 or Escherichia coli ATCC25922 was inoculated. These experiments were compared with a control infusion. The infusion was dropped at a flow rate of 40 mL/h and replaced at 24-h intervals for seven days. Samples were collected 24 h after drop initiation. S. epidermidis was not detected in droplets between Days 1 and 6, while in-line filters 1 and 2 showed droplets containing 6-10 CFU/mL on Day 7. E. coli was not detected in any of the filters. Flow rates below 40 mL/h were observed on Day 7 in in-line filter 3 in studies of S. epidermidis, and on Days 4 and 3 in in-line filters 2 and 3, respectively, in studies of E. coli. Our study revealed differences in bacterial removal and flow rate under high inoculation among each of three tested in-line filters. We suggest the continuous use of in-line filters for a maximum of six days, while reductions in flow rate after 48 h of continuous use should be carefully noted.

Identification of a frit-related sample carryover in newborn screening by tandem mass spectrometry

The need for high-throughput analysis of multiple analytes for inborn errors of metabolism in newborn screening (NBS) has led to the introduction of tandem mass spectrometry (MS/MS) into the NBS laboratory. In a flow-injection analysis (FIA), the predominant MS/MS method utilized for NBS, samples are introduced directly into the mass spectrometer without chromatographic separation. When a high-throughput FIA-based MS/MS method is implemented on newer generations of mass spectrometers with increased sensitivity, the risk of carryover and contamination increases. In the present study, we report the carryover of ornithine identified during the implementation of the NeoBase™ 2 (PerkinElmer) non-derivatized kits on the Xevo-TQD platform (Waters Corporation) and describe the source of the carryover, which was traced to the stainless-steel frit-type inline filter. Furthermore, a possible compound-dependent interaction with the stainless-steel frit is suggested based on the structure of ornithine and its effect on separation techniques. Investigation and mitigation of carryover can be a time and resource consuming process, and to this end, our report on identification of a stainless-steel frit as the source of delayed elution and carryover of ornithine should be recognized as a rare, albeit possible source of carryover in FIA-MS/MS methods adopted for NST.

Synthesis of Strictly Inline Filters With Transmission Zeros

In this article, we discuss the synthesis of a strictly inline filter configuration allowing the placement of up to four transmission zeros (TZs) in the frequency response. This configuration [here referred to as extracted-zero (EZ)] is often adopted in the practice, but the dimensioning generally resorts to empirical strategies and numerical optimization, being no synthesis-based approaches available till now. The topology of these filters is represented by an array of coupled resonators without cross couplings, with source and load coupled to internal resonators (instead of the first and last as in the classical all-pole filters). We show here how to compute the equivalent circuit parameters (coupling coefficients and resonating frequencies) once a suitable approximating frequency characteristic has been devised. Several synthesis examples are presented, and it is shown how filters of this type, previously empirically designed, and actually fabricated, can be obtained with the new design approach.

Dielectric TM-Mode Y-Shaped Doublet Structure

This paper discusses dielectric TM-mode filters based on high permittivity Y-shaped ceramics. It is shown that this type of ceramic operates as a dual-mode resonator and therefore contributes two reflection zeros as well as one transmission zero (TZ) to the filter response. Hence, it can be interpreted as a doublet structure and used for the realization of quasi-elliptical filter responses of different order. The dual-mode resonator can be used in multiple different filter set-ups: On the one hand, a combination with classical TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{010}$</tex-math></inline-formula> -mode resonators is possible to allow the realization of TZs in an in-line filter configuration without using cross-coupling apertures. Therefore, negative or diagonal cross-couplings, which are often difficult to realize and handle, can be avoided. On the other hand, several Y-shaped ceramics can be coupled directly with each other to increase the number of TZs to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n_{fz}=n/2$</tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> is the order of the filter. Finally, it is shown that even a combination with extracted pole elements is realizable. Prototypes based on modular segments are manufactured as proof of concept.