For instance, a microfluidic ATP-bioluminescence sensor for the

For instance, a microfluidic ATP-bioluminescence sensor for the detection of airborne microbes using commercial available photo-diodes has been recently reported [27]. Although optical absorption detection is compatible with microfluidics, they suffer from relatively poor detection limits due to the short effective path length found in microfluidic channels [34]. Consequently, fluorescence detection remains the dominant optical detection technique in microfluidics. Here the conjugation of affinity markers (e.g. antibodies, DNA etc.) with fluorescent compounds like fluorescein isothiocyanate (FITC), phycoerythrin (PE) cyanin- or Alexa-dyes is most commonly used. Alternative approaches are based on the incorporation of two fluorescence molecules into the biosensor, using fluorescence resonance energy transfer (FRET) [35].

Other optical methods include chemiluminescence (CL), bioluminescence (BL) and Surface Plasmon Resonance (SPR) biosensors. While chemiluminescence describes the generation of light due to release of energy during a chemical reaction, SPR measures changes in refractive index caused by structural alterations in the vicinity of a thin film metal surface [36]. The numerous chemiluminescence (CL) applications in microfluidic analysis systems using immobilized enzymes, antibodies or nucleic acids have been recently described [37-39]. In turn, electroanalytical methods are highly compatible with micro- and nanomachining (MEMS) technology and can be segmented into current (amperometric), potential (potentiometric) or impedance (impediometric) techniques [40-43].

Evolving from ISFETs, a recent technology combines potentiometry and optical detection, known as light addressable potentiometric sensor (LAPS), that can be used for the detection of pathogen E. GSK-3 coli [44]. Alternative detection methods for pathogen sensing include the application of silver dots for direct optical density measurements using a scanometric reader [45,46], or biosensors using resonance light scattering (RLS) techniques based on nanometer-sized metallic particles (mostly gold) covalently linked to antibodies. These metal colloidal particles radiate energy in the form of scattered light when illuminated by a white light source [47]. Altogether, LOC devices present themselves as a flexible technology platform that can be readily adapted to specific identification needs. A whole range of materials and mode of detection can be specifically selected for either low cost applications or high end analysis. Having reviewed the various materials and detection methods employed in lab-on-a-chip devices, we now provide a detail list of LOC studies grouped by class of target analytes.3.

These acrylic microspheres were hydrophobic in character with a

These acrylic microspheres were hydrophobic in character with a surface modified acryloxysuccinimide functionality (poly-nBA-NAS) for the immobilization of the enzyme. They were synthesized via photopolymerization. As the microspheres are hydrophobic, the AOX immobilization will be confined to the surface of the spheres, thus allowing the enzymatic reaction of AOX and formaldehyde to occur at the surface. With a large surface area of the microsphere to be use as a potetiometric biosensor membrane and favorable surface diffusion conditions, the analytical performance of the formaldehyde biosensor can be improved.2.?Experimental Section2.1.

Materials2,2-Dimethoxy-2-phenylacetophenone (DMPP), sodium tetrakis [3,5-bis (trifluro-triethyl) phenyl] borate (NaTFPB), hydrogen ionophore I (tridodecylamine), sodium dihydrogen phosphate (NaH2PO4) were obtained from Fluka.

Sodium hydroxide (NaOH), sodium dodecyl sulphate (SDS), acetic acid, acetyl acetone from Systerm. In addition, 2-hydroxyethyl methacrylate (HEMA), poly(HEMA) commercial, 2-hexanediol diacrylate (HDDA), alcohol oxidase enzyme (AOX) from Hansenula polymorpha, bovine serum albumin (BSA), Bradford reagent, all were from Sigma Aldrich. N-acryloxysuccinimide (NAS) and tris(hydroxymethyl) aminomethane (Tris-HCl) were purchased from Acros Organics and Duchefa Biochemie, respectively.

Formaldehyde solution was obtained from BDH, n-butyl acrylate (nBA) from Merck, hydrochloride acid 37 % (HCl) from Riedel-de Haen, di-sodium hydrogen phosphate (Na2HPO4) from Hamburg Chemical, ammonium acetate from Scharlau while both Bactor agar and 1,4-dioxane were from Ajax Chemicals.

All chemicals were of analytical grade and used without further purification. Standard buffer solutions were prepared with deionized Batimastat water.2.2. Synthesis of Poly(nBA-NAS) MicrospheresPoly(nBA-NAS) microspheres were prepared via photopolymerization in the form of an emulsion. A mixture of 4 mL of nBA monomers, 0.09 g DMPP, 400 ��L HDDA, 0.1 g SDS, 10 mg NAS and 10 mL deionized water was prepared in a sample bottle. The resulting emulsion turned milky white after sonication for 5 min. The milky solution was then photocured for 300 s under continuous purging with nitrogen gas in an ultraviolet exposure unit (R.

S. Ltd.) of 15 Watt light intensity GSK-3 at a wavelength of 350 nm. Poly(nBA-NAS) microspheres were isolated by centrifugation (4,000 rpm, KUBOTA) for 8 min and finally washed a few times with 0.01 M sodium phosphate buffer solution (pH 8.0). Clean poly(nBA-NAS) microspheres were dried at room temperature and kept at 4 ��C when not in use.2.3.

e DNA binding protein Deaf 1 Cnc, maf S, and Deaf 1 are reported

e DNA binding protein Deaf 1. Cnc, maf S, and Deaf 1 are reported to interact with the Hox protein Deformed to regu late segmentation, but their roles in other developmental events are not known. Our results provide a possi ble role of these proteins in Drosophila development by promoting Notch signaling. Another transcription factor that we found to play an agonistic role in Notch signaling is the homeobox con taining protein Aristaless. Al has been tentatively linked to Notch signaling, as it cell autono mously represses the Notch ligand Delta in the pretarsus during leg morphogenesis. It is possible that al is involved in a Notch mediated lateral inhibition mechan ism, where al expressing cells remain undifferentiated by favoring active Notch signaling whereas their neighbor ing cells are free to express Delta and differentiate.

It has also been shown that Notch mutant clones in the developing leg disk show diminished al levels, suggesting that al is a Notch target gene. This would be the pre dicted relationship in a lateral inhibition system, where a Notch al positive feedback loop would amplify the Notch activity differences between neighboring cells. Two additional transcription factors that have been previously shown to be involved in leg morphogenesis were found to promote Notch signaling, Bonus, a homologue of the vertebrate TIF1beta transcriptional cofactor, and crooked legs, a zinc finger pro tein. Notch signaling is known to play an important role in Drosophila leg development, and the recovery of these two transcription factors as modifiers of Notch induced E m3 expression suggests that bon and croI may function to modulate Notch target gene output in the developing leg.

We also identified the Drosophila orthologues Cilengitide of two mammalian proto oncogenes kayak, and c Myb, as positive regulators of Notch signaling. Although a direct functional link between these proteins and Notch signaling has not been described, kayak has been shown to interact genetically with Hairless and c Myb genetically interacts with bon, a novel Notch modifier described above. In addition, our data reveals a synergistic relationship between the positive regulator of Ras signaling, 14 3 3��, and Notch. Once again, the pro tein interaction network shows extensive contacts between 14 3 3�� and the chromatin machinery, suggest ing a mechanism for modulating Notch target transcrip tion through Su mediated chromatin modifications.

Interactions between Notch and oncogenic pathways are of particular interest, as the involvement of Notch in cancer biology and stem cell maintenance is becoming increasingly apparent. An unexpected Notch target transcription modifier identified in the screen is the Notch target gene Tram track. We found that targeting of ttk with dsRNA resulted in reduced Notch activity. In contrast, ttk expression itself has been shown to increase in response to ectopic Notch activity. The RNAi treatment data suggest that ttk may function in a posi tive feedbac

ctive NF ��B inhibitor Bay11 7082, which blocks activation of NF

ctive NF ��B inhibitor Bay11 7082, which blocks activation of NF ��B signaling, attenuated ET 1 induced CO 2 protein and mRNA e pression in bEnd. 3 cells. To determine whether the involvement of NF ��B in ET 1 induced responses mediated through NF ��B trans location, as shown in Figure 5C, ET 1 time dependently stimulated translocation of NF ��B p65 from cytosol into nucleus determined by Western blot. A ma imal re sponse was obtained within 90 min and sustained over 120 min. Moreover, we also confirmed the NF ��B p65 translocation by an immunofluorescence staining. The imaging data confirmed that ET 1 stimu lated the p65 translocation at 90 min, which was inhib ited by pretreatment with Bay11 7082. We further demonstrated that ET 1 stimulated translocation of NF ��B p65 was attenuated by pretreat ment with the inhibitor of ETB receptor, MEK1 2, p38 MAPK, JNK1 2, or NF ��B.

To fur ther verify that NF ��B p65 is essential for ET 1 induced CO 2 e pression, as shown in Figure 5E, transfection with p65 siRNA significantly reduced the p65 protein e pression and the ET 1 induced CO 2 e pression. The results suggested that ET 1 stimulated NF ��B translocation mediated Brefeldin_A through ETB receptor, ERK1 2, p38 MAPK, and JNK1 2 is required for CO 2 induction in bEnd. 3 cells. Involvement of NF ��B in CO 2 gene promoter activity stimulated by ET 1 We have found that ET 1 stimulates translocation of NF ��B p65 leading to CO 2 e pression. Ne t, we e amined whether activation of NF ��B is essential for ET 1 induced CO 2 gene up regulation. The transcriptional activity of NF ��B was evaluated by a promoter luciferase ac tivity assay.

As shown in Figure 6A, ET 1 enhanced NF ��B transcriptional activity in a time dependent manner with a ma imal response within 60 min, which was sig nificantly inhibited by pretreatment with an inhibitor of NF ��B. Moreover, pretreatment with BQ 788, GPA2, GPA2A, U0126, SB202190, or SP600125 attenuated NF ��B transcriptional activity stimulated by ET 1, demonstrating that ET 1 enhances the NF ��B transcriptional activity through an ETB dependent activation of MAPKs. Subse quently, we determined that ET 1 stimulates NF ��B p65 binding activity in a time dependent manner by ChIP PCR analysis. ET 1 stimulated NF ��B p65 binding activity was inhibited by pretreatment with U0126, SB202190, SP600125, Bay11 7082, or BQ 788.

In addition, we have demon strated that ET 1 time dependently induces CO 2 pro moter activity. We further demonstrated that ET 1 increased the CO 2 promoter activity was significantly inhibited by pretreatment with BQ 788, GPA2, GPA2A, U0126, SB202190, SP600125, or Bay11 7082, suggesting that ET 1 stimulates CO 2 promoter activity via the ETB dependent activation of MAPKs and NF ��B in bEnd. 3 cells. To further ensure that NF ��B indeed mediates ET 1 induced CO 2 pro moter activity through binding to its regulatory element within the CO 2 promoter region, the wild type and mutated by a single point mutation of the NF ��B binding site CO 2 promoters

According to the type of real sample (apple juices for babies) in

According to the type of real sample (apple juices for babies) in which the analyte is determined, the systems described in this work can be very promising tools for quality control purposes in food industry. It is noteworthy that this is the second time that exclusively electrochemical methods have been used to determine AA in commercial baby juices [9].Finally, these devices were also structurally characterized by means of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). AuSNPs and AuSNPs/CeO2 nanocomposite were characterized by UV-vis spectroscopy, X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM;.2.?Experimental Section2.1. Reagents and MaterialsMethyltrimethoxysilane (MTMOS) was from Merck (Darmstad, Germany) and HCl was from Panreac (Barcelona, Spain).

KH2PO4 and K2HPO4 for phosphate buffer solution (PBS) and potassium hexacyanoferrate(II) were from Fluka (Buchs, Switzerland). Sodium citrate trihydrate was purchased from Scharlau (Scharlab, Barcelona, Spain) and potassium tetrachloroaurate(III), ascorbic acid and nanopowder cerium(IV) oxide (99.95%) form from Sigma-Aldrich (Sigma, Steinheim, Germany). Graphite powder natural, high purity-200 Mesh, 99.9999% (metal basis), was from Alfa-Aesar (Johnson Matthey GmbH, Germany). All reagents were of analytical grade and used as received without further purification. Nanopure water was obtained by passing twice-distilled water through a Milli-Q system (18 M??cm, Millipore, Bedford, MA, USA). Glass capillary tubes, i.d. 1.15 mm (A = 0.0415 cm2), were used as the bodies of the composite electrodes.

The nitrogen used for getting inert atmospheres and deaerating solutions in the measuring cell was N-55 type.2.2. InstrumentationThe synthesis of the SNGC material was carried out by sonicating with a high power SONICATOR 3000 ultrasonic generator from MISONIX Inc. (Farmingdale, NY, USA) equipped with a 13-mm titanium tip, that provides a maximum output power of 600 W.The voltammetric measurements were made on an Autolab? PGSTAT20 (Ecochemie, Utrecht, The Netherlands) potentiostat/galvanostat connected to a personal computer and a 663 Metrohm VA Stand module, using the software GPES (General Purpose Electrochemical System) 4.9 ver. for waveform generation, data acquisition and elaboration. The experiments were carried out in a single-compartment three-electrode cell, at room temperature (25 �� 1 ��C).

The counter electrode was a platinum wire, and a silver/silver chloride/3M KCl electrode was used as the reference. The composite-filled glass capillary tubes were used as the working electrode.UV-Visible measurements were made with the Batimastat Jasco 32 software using a Jasco V-550 (Easton, MD, USA) UV-visible spectrophotometer connected to a personal computer.

Optimization, especially bio-mimetic strategy-based optimization

Optimization, especially bio-mimetic strategy-based optimization in WSNs, is a very active research area. Papers published in this area are highly diverse in their approaches and implementations. To the authors’ knowledge, there is no article which provides survey of the area. However, some work has been done addressing the various issues individually (e.g., energy efficiency, QoS or security) and they tend to overlook the whole scenario of collective optimization approach which encompasses these two or three WSN issues. In [6], an extensive survey was done on WSNs taking into account the topic of overall computational intelligence, but with some focus on bio-mimetic strategies. The more recent survey [7] narrowed down its focus to an ant colony optimization (ACO)-based approach to solve several issues in WSNs.

Moreover, in [8] the authors discussed a protocol based on ACO, and two fundamental parameters, QoS and reputation are used. Both works exclude other popular techniques like PSO and GA. In [9], some issues of WSNs have been addressed using only PSO. A number of papers have reported works on energy efficient clustering [10�C13] and prolonging network lifetime [14] in WSNs using PSO.Considering these points, we feel that now is an appropriate time to put recent works into perspective and take a holistic view of the field. This article takes a step in that direction by presenting a survey of the literature in the area of bio-mimetic optimization strategies in WSNs focusing on current, ��state-of-the-art�� research.

This paper aims to present a comprehensive overview of optimization techniques especially used in energy minimization, ensuring security, and managing QoS in WSN applications. Finally, this work points out open research challenges and recommends future research directions.Section 2 presents a brief overview on optimization and Section 3 presents the rationale for optimization in WSN in details. Section 4 provides an overview of existing approaches of bio-mimetic optimizations including hybrid approaches in WSNs. Open research challenges and suggestions for future research directions are presented in Section 5. Finally Section 6 concludes the work and points to areas of potential future work.2.?Optimization Strategies2.1. What is Optimization?Optimization is a term that covers almost all sectors of human life and work; from scheduling of airline routes Carfilzomib to business and finance, and from wireless routing to engineering design.

In fact, almost all research activities in computer science and engineering involve a certain amount of modeling, data analysis, computer simulations, and optimization [15]. In a word, it is an applied science that tries to obtain the related parameter values which facilitate an objective function to produce some minimum or maximum value [2].

We also found that BiFC efficiency and the low false-positive rat

We also found that BiFC efficiency and the low false-positive rates of the BEVL-BiFC system was not affected whether Jun was on upstream or downstream of C-terminal fragment of mLumin.Figure 1.BiFC efficiency of the mLumin-based BiFC system with a bicistronic expression vector. (a) Fluorescence imaging and (b) BiFC efficiency analysis of COS-7 cells cotransfected with pBud-Ln-Fos(��Fos)-Lc-Jun or pBud-Ln-Fos(��Fos)-Jun-Lc and …3.2. Detection of the Interaction between K-Ras and RBD Using BEVL-BiFC SystemTo verify the robustness of the BEVL-BiFC system in the detection and analysis of PPIs, we examined the plasma membrane (PM) localized protein K-Ras and RBD as a PPI model. K-Ras is usually anchored to cell membranes because of the presence of an isoprenyl group on its C-terminus (Figure S2 in the Supporting Information).

As a small GTPase, K-Ras is phosphorylated by guanine nucleotide exchange factors (GEFs) when upstream signal proteins are activated, and then K-Ras transfers the signal to downstream effector proteins (e.g., Raf-1). K-Ras acts as a molecular on/off switch, conversed between active K-Ras bound with GTP (K-Ras-GTP) and inactive K-Ras bound with GDP (K-Ras-GDP). Using immunoblotting and FRET imaging approaches [21], it has been reported that K-Ras b
Corrosion of reinforcing steel, generally caused by carbonation or Cl?, is the most important factor causing severe degradation of the durability of reinforced concrete (RC) structures. Especially, Cl? from the concrete itself or the environment leads to pitting corrosion which will quickly result in a remarkable reduction of the cross section of the reinforcing steel [1,2].

The durability deterioration of RC structures finally leads to very high repair costs, sometimes much greater than the initial construction cost, and in some extreme situations, can result in the collapse of the structure [3]. With the development of global warming and further deterioration of the environment, the service condition of RC structures has recently GSK-3 become much harsher.Over the past two decades, structural health monitoring (SHM) has gained worldwide acceptance as an affordable way to obtain real-time data on the health, and consequently, on the safety and the serviceability of civil infrastructure systems [4]. There have been many sensing technologies applied in earthquake engineering, wind engineering and life-cycle performance evaluation, such as the fiber optic sensing technique [5], the wave propagation-based piezoelectric ceramic (PZT) sensing technique [6�C9] and the smart cement-based sensing technique, etc. [10,11]. Recently, future trends in the development of sensing technologies and SHM in civil engineering have been critically reviewed and put forward [12�C14].

1 PrincipleDInSAR provides information on the change in distance

1. PrincipleDInSAR provides information on the change in distance through time between the ground and the satellite sensor. The technique is based on the change in phase between two Synthetic Aperture Radar (SAR) acquisitions. Details on the principles of radar differential interferometry can be found in [20, 21]. A differential interferogram is a map of the surface displacement along the line of sight occurring between the acquisition dates of the two images. The DInSAR technique has been successfully applied for detecting and mapping surface displacements caused by natural and anthropic phenomena such as earthquakes [22], ice stream flows [23], volcanic activity [24] and land subsidence [25, 26].However, some severe limitations prevent systematic use of this technique.

The major limitation is the loss of signal coherence [20]. This loss of coherence is due to changes in the physical and geometric characteristics of the targets. The signal is also affected by atmospheric effects [27], related to fluctuations of the atmosphere between the two image acquisitions, changing the refractive index of the layer crossed by the wave, and therefore, its optical path (atmospheric delay). They can have similar signatures as ground displacement [28]. The loss of coherence produces a high spatial frequency phase noise, whereas atmospheric effects produce lower spatial frequencies that can be misinterpreted as displacements [29]. In our study, these limitations were enhanced by specificities of the local context. The dense vegetation that covers most of La Reunion is responsible for low coherence in the C-band.

In the study area, the tropical climate and the steep, high relief (up to 3,000 m) increases the possibility of fluctuations of the atmospheric layer over the studied area. As shown by [14, 30], the L-band of radar sensors (wavelength ranges between 21.41 and 24.57 cm) generally provides a higher coherence than the C-band (wavelength ranges between 5.06 to 5.71 cm) over non-urban areas. Indeed, due to its higher wavelength, L-band waves penetrate deeper into the vegetation cover and provide information from the more stable scatterers located on the ground surface. It is, therefore, less sensitive to temporal decorrelation due to vegetation changes between two acquisitions.

As pointed out by [31], the DInSAR technique is well adapted for the detection and monitoring of landslides on the Anacetrapib slopes facing away from the SAR look vector. In addition, the ground displacement rates have to be compatible with the time sampling of the DInSAR technique. The L-band is particularly adapted to investigate decimetric displacements In this case, one interferometric fringe corresponds to a movement of 11.25 cm (half of the wavelength) in the line of sight of the satellite (corresponding to 2.8 cm for the C-band).

In this paper, fluctuations in relative humidity have been studie

In this paper, fluctuations in relative humidity have been studied, as humidity is particularly important for dimensional changes which may compromise the condition of works of art [3, 9, 10].Many museum objects, artifacts and works of art are composed of complex hygroscopic materials (for example, painted and unpainted wood, ivory, varnishes and glues) that respond dimensionally to variations in relative humidity and temperature in order to maintain equilibrium with the surrounding environment [11-13.] Dimensional changes may occur with fluctuations in humidity; material expansion or swelling may take place with increased values of RH (and moisture content of the material) and contraction or shrinking may be provoked with decreased humidity.

Swelling and shrinking of the wooden support of a panel painting, frame or sculpture can lead to the development of cracks and irreversible buckling or warping or the paint or wooden layers. Further, such dimensional changes may critically influence the strength of adhesion of the constituent layers in a painting or polychrome work of art, and may provoke subsequent loss of mechanical integrity [10-14]. As painted artworks are multilayered structures composed of heterogeneous materials with varying porosity, hygroscopicity and flexibility, with dimensional changes which follow a change in humidity, a multitude of non-uniform internally generated stresses and strains may be generated [15-18].The amount of stress or load which a material can safely undergo before fracture is governed by Hooke’s law, which forms the basis of the theory of elasticity.

In brief it states that for certain ranges of stress, the strain produced is proportional to the stress applied and disappears on its removal (elastic region); whereas in the limit of proportionality the linearity ceases (plastic region), the material reaches the elastic limit (yield point), accompanied with permanent change (strain) leading to fracture even without further loading. The elastic limit has been used to define the onset of damage in works of art and related materials [17-21]. In this context, if RH fluctuations can cause shrinking or swelling stresses that exceed the elastic limit, damage is provoked and fracture is expected in case of further loading. However, even following irreversible and permanent changes (damage), effects of dimensional changes may initially be invisible [22, 23] until visible and irreversible damage occursThe cumulative effects of dimensional displacement may present visible phenomenon which are well-known to conservators; for example, these can range from changes in craqueleur patterns on the surface of a varnished painting to paint losses, detachments among layers Carfilzomib and cracks in a wooden support [24, 25].

The electrostatic force balance technology is adopted in the circ

The electrostatic force balance technology is adopted in the circuit, and the application range of vacuum microelectronic accelerometer is greatly extended.2.?Structure and Working PrincipleThe structure diagram of a vacuum microelectronic accelerometer is illustrated in Figure 1. The mechanical components comprise four cantilever beams, a proof mass and a micro-silicon field emission tip array. The electrodes include a cathode, an anode and a feedback electrode. Meanwhile, the protecting chain is designed. It will prevent the damage of the tip array and realize over loading self-protection. When the acceleration exceeds the measurement range, the anode will contact with the protecting chain, and avoid the collision between the anode and the tip array.Figure 1.

Structure diagram of vacuum microelectronic accelerometer.This accelerometer has been designed and fabricated. The dimensions of the accelerometer are obtained. Figure 2 is the SEM diagram of single tip. The bottom pyramid is the tip, and the top plate is the SiO2/Si3N4 cap protecting the tip from being eroded. Finally, the cap will be removed after the tip acuity. When a big enough DC voltage is added between the tip and the anode electrode, the tip will emit electrons under high electric field.Figure 2.The SEM diagram of the single tip.The vacuum microelectronic accelerometer works in electrostatic force balance mode. The working principle is that by applying a forward bias voltage between the anode and cathode, when the bias voltage is large enough, the tip array begins to emit electrons under high electric field, and then the electrons form a diode forward current.

When the bias voltage is constant and there is an acceleration acting on the accelerometer, the proof mass will produce a displacement, and result in the change of emission current. Using current detecting circuit and electrostatic negative feedback system can make the proof mass maintain the balance position, and then the acceleration is obtained by measuring the output voltage.3.?Mathematical Model and System-Level Analysis3.1. The Mathematical ModelMatlab was used to build the mathematical model of the vacuum microelectronic accelerometer. The model is composed of different function blocks based on Laplace transforms. In general, a vacuum microelectronic accelerometer with a feedback control system is not a linear system.

Assumptions and approximations are used to linearize the system.3.1.1. The Sensing PartThe proof mass is the sensing part of the accelerometer. It can be considered as a suspended mass-spring-damping system [10]. Using Laplace transforms, the dynamic performance of the proof mass can be expressed as:G1(s)=��xm��a=1ms2+bs+k(1)where m, b, and k represent the mass, damping Drug_discovery coefficient, and spring constant of the proof mass, respectively. ��a is the external acceleration, and ��x is the displacement of the proof mass.