Table of contents

The electro-static self-assembly (ESA) process has proved to be extremely successful in creating multilayer coatings with properties that can be tailored for particular applications. In this process, almost any surface with charged functional groups can be used as a substrate. Alternate dipping in solutions having ions of opposite charge builds up the layers through ionic bonding. One particular application of this process could be to form multi-functional biocompatible coatings on microelectromechanical systems devices intended for use in vivo. In this paper, we describe two different models of the process based on the cellular automata techniques used in the field of artificial life. The output of the models consists of three parameters as a function of layer: ionic coverage, film height and film roughness. The results of the models are compared to experimental data to determine which of them more accurately describes the ESA process.

Fe nanoparticles, with both fcc and bcc structures and with a C shell that protects against oxidation, were generated by the laser-assisted photolytic chemical vapor decomposition of ferrocene (FeCp₂). Amorphous W and WN_0,3nanoparticles were formed by laser ablation (LA) of solid W in Ar and in N₂ ambient, respectively. Laser-assisted chemical vapor deposition of W yielded crystalline W nanoparticles (β phase) from a WF₆/H₂/Ar gas mixture. ArF excimer laser was used as the radiation source in all the experiments. Measurements and analysis of the emitted blackbody-like radiation from the laser heated particles were performed and dominant cooling processes such as evaporation and heat transfer by the ambient gases were identified. The particles could be heated up to the boiling and melting point of Fe and W, respectively. Lognormal particle size distributions were found for Fe/C and W nanoparticles generated by vapor decomposition or deposition processes respectively, and then modeled at low particle concentration (with no coagulation). The thickness of the C shell was practically independent of the laser fluence, while the size of the Fe core could be varied for the Fe/C particles. The LA yielded no lognormal-type distribution for the amorphous WN_0,3 particles.

Conduction noise measurements were carried out in the 0.3–45 Hz frequency range on Au films covered by a thin layer of tungsten trioxide (WO₃) nanoparticles. Exposing the films to alcohol vapor resulted in a gradually increased noise intensity which went through a maximum after an exposure time of the order of 15 min. The maximum noise intensity could increase by several orders of magnitude above the initial level. Longer exposure times made the noise decrease and approach its original value. This effect was not observed in the absence of WO₃ nanoparticles. The phenomenon is discussed in terms of a new 'invasion noise' model in which the noise is related to the insertion and extraction of mobile chemical species.

Polymeric light-emitting diodes with sufficient brightnesses, sufficient efficiencies, sufficiently low driving voltages, and various interesting features have been reported. The relatively short device lifetime, however, still remains as a major problem to be solved before any commercial applications can be realized. In this regard, carbon nanotubes have recently been proposed as more robust electron field emitters for flat-panel displays. We have synthesized large arrays of vertically aligned carbon nanotubes, from which micropatterns of the aligned nanotubes suitable for flat-panel displays were fabricated on various substrates. In this paper, we summarize our work on the synthesis and microfabrication of light-emitting polymers and carbon nanotubes for displays with reference to other complementary work as appropriate.

For many applications, it is essential to be able to control the interface between devices and the biological environment by nanoscale control of the composition of the surface chemistry and the surface topography. Application of molecular thickness coatings of biologically active macromolecules provides predictable interfacial control over interactions with biological media. The covalent surface immobilization of polysaccharides, proteins and synthetic oligopeptides can be achieved via nanometres thick, interfacial bonding layers deposited by gas plasma methods, and the multi-step coating schemes are verified by XPS analyses. Interactions between biomolecular coatings and biological fluids are studied by MALDI mass spectrometry and ELISA assays. Using a colloid-modified AFM tip, quantitative measurement of interfacial forces is achieved. Comparison with theoretical predictions allows elucidation of the key interfacial forces that operate between surfaces and approaching bio-macromolecules. In this way, it is possible to unravel the fundamental information required for the guided design and optimization of biologically active nanoscale coatings that confer predictable properties to synthetic carriers used for the fabrication of bio-diagnostics and biomedical devices. By studying the relationships between interfacial forces and the adsorption of proteins, we have established the key properties that make specific polysaccharide coatings resistant to the adsorption of proteins, which is applicable to biomaterial, biosensor and biochip research.

To improve mixing, obstacles have been placed in the channel to try to disrupt flow and reduce the diffusion path. The disruption to flow velocity field alters the flow direction from one fluid to another. In this way, convection may occur to enhance the mixing. Ideally, properly designed geometric parameters, such as layout and number of obstacles, improve the mixing performance without increasing the pressure drop. In this work, CoventorWare^TM, a commercial computational fluid dynamics tool for microfluidics was used to study the mixing of two liquids in a 'Y' channel. The results indicate that asymmetric layout of the obstacle has more effect on the mixing than the number of obstacles. Placing obstacles in the microchannels is a novel method for mixing in microfluidic devices, and the results can provide useful information in the design of these devices.

An investigation aiming to seek a correlation between ablation rates and various polymer thermal properties, based on experimental ablation data generated for 14 polymers commonly used in microfluidics, is presented. A statistical analysis was carried out for laser fluence against various polymer descriptors and/or their combinations. The results of the analysis show a relatively high correlation coefficient of 0.82 for polymer ablation data when we compare fluence against the product of ablation rate and the difference between the glass transition temperature and room temperature.

The effects of polymer properties are also illustrated by an investigation of ablation behaviour of DNQ/novolak thin films, which had been exposed to different levels of UV radiation prior to laser ablation, using atomic force microscopy. The surface characteristics of the thin films following laser irradiation are discussed in terms of differences in laser absorption and the glass transition temperature of the films. The results are consistent with the glass transition temperature being a critical factor affecting laser/polymer interaction.

Thin films were made by spinning a dispersion of tin-doped indium oxide particles, having an average diameter of 14 nm, onto glass substrates. As-deposited thin films displayed a resistivity ρ of 0.3 Ω m and some optical absorption. Annealing in vacuum at 200–400^oC for 2 h, and subsequently in air at 500^oC for 2 h, produced films with ρ ≈ 10⁻³ Ω m and a visible transmittance exceeding 90%. Leaving out the vacuum treatment yielded higher resistivity.

This paper presents several digital image processing algorithms for the enhancement of scanning tunnelling microscopy (STM) images. The overall aim of the project is to achieve high-quality atomic-scale imaging of molecules that have been adsorbed sparsely onto a substrate. As STM experiments necessarily involve very small scanning movements and low tunnelling currents, a low signal-to-noise ratio in the image will always be an issue. Hence effective post-processing of the images will extend the power of STM in imaging molecular adsorbates.

Algorithms are presented for the calibration of the microscope (both before and after data collection) and for removal of various forms of noise. Graphite imaging has been successfully used as a reliable method for instrument calibration. This calibration is required due to the undesirable effects that are characteristic of STMs, which result in improper scaling and skewing of images. Image enhancement techniques have been created to reduce the noise effects due to thermal drift, tip hysteresis and artifacts associated with the scanning mechanism. These techniques were developed for graphite images, but have also been successfully applied to imaging of molecular adsorbates.

We describe a novel technique for the fabrication of nanoscale structures, based on the development of localized chemical modification caused in a polymethylmethacrylate (PMMA) resist by the implantation of single ions. The implantation of 4 MeV He ions through a thin layer of PMMA into an underlying silicon substrate causes latent damage in the resist. On development of the resist we demonstrate the formation within the PMMA layer of clearly defined etched holes, of typical diameter 30 nm, observed using an atomic force microscope employing a carbon nanotube SPM probe in intermittent-contact mode.

This technique has significant potential applications. Used purely to register the passage of an ion, it may be a useful verification of the impact sites in an ion-beam modification process operating at the single-ion level. Furthermore, making use of the hole in the PMMA layer to perform subsequent fabrication steps, it may be applied to the fabrication of self-aligned structures in which surface features are fabricated directly above regions of an underlying substrate that are locally doped by the implanted ion. Our primary interest in single-ion resists relates to the development of a solid-state quantum computer based on an array of³¹P atoms (which act as qubits) embedded with nanoscale precision in a silicon matrix (Kane B E 1998 Nature393 133–7). One proposal for the fabrication of such an array is by phosphorus-ion implantation. A single-ion resist would permit an accurate verification of³¹P implantation sites. Subsequent metallization of the latent damage may allow the fabrication of self-aligned metal gates above buried phosphorus atoms.

Carbon nanotubes have fascinating physical properties. In order to use these novel one-dimensional structures for applications (such as in electronic devices, mechanical reinforcements and nano-electromechanical systems) the structure of nanotubes needs to be tailored and various architectures have to be configured using nanotube building blocks. Firstly, in this paper we focus on the directed and self-assembly of nanotubes on planar substrates into hierarchical structures that include oriented arrays, and ordered bundles. These structures are achieved by patterning substrates with or without metal catalysts. Growth of nanotubes is typically achieved by chemical vapor deposition. Various strategies to build two- and three-dimensional architectures of nanotubes are described by this method. In addition to creating pristine nanotube arrays on planar substrates, the paper also covers some of our recent efforts in fabricating nanotube polymer hybrids. Recent efforts and challenges in manipulating nanotubes on surfaces and measuring transport properties are discussed. Results of noise measurements carried out on individual nanotubes; surface potential mapping and very high, long-term current carrying capacity (10⁹–10¹⁰ A cm⁻²) are reported. In conclusion, a perspective is given on our recent efforts in creating controlled structures with nanotubes and measuring some of their properties.

So far proposed quantum computers use fragile and environmentally sensitive natural quantum systems. Here we explore the new notion that synthetic quantum systems suitable for quantum computation may be fabricated from smart nanostructures using topological excitations of a stochastic neural-type network that can mimic natural quantum systems. These developments are a technological application of process physics which is an information theory of reality in which space and quantum phenomena are emergent, and so indicates the deep origins of quantum phenomena. Analogous complex stochastic dynamical systems have recently been proposed within neurobiology to deal with the emergent complexity of biosystems, particularly the biodynamics of higher brain function. The reasons for analogous discoveries in fundamental physics and neurobiology are discussed.

We investigate excimer laser ablation of TiNi shape memory alloy thin sheets and films using an image projection system as a tool for micromachining and patterning. Characteristics of material removal by KrF excimer laser induced ablation at 248 nm and the dependence of material removal rates on laser parameters such as fluence and pulse frequency are explored. Fluences at the workpiece using a 10×projection lens were up to 2.5 J cm⁻² with pulse repetition rates up to 100 Hz. Conventional chrome-on-quartz masks were used for pattern transfer. Material removal mechanisms and rates of material removal were investigated for thin film samples and thin sheet samples having thicknesses of 3 and 150 μ m respectively.

This paper presents results on the laser micromachining of TiN films. Machining performance was evaluated in terms of patterning quality and the ability to remove TiN with minimal interference with an underlying sacrificial layer. TiN was arc-deposited onto (100) silicon substrate with chromium (Cr) and copper (Cu) sacrificial layers. Films were also deposited onto bare silicon substrates under the same conditions. These films were analysed for their composition and structure using Rutherford backscattering spectroscopy and x-ray diffraction techniques. Laser micromachining was performed using a KrF excimer laser at 248 nm. The effect of fluence and number of shots on the machined features has been investigated in detail. The patterned features were examined using optical, confocal and scanning electron microscopes. The characteristics observed were analysed and compared in all three sets of samples. The results showed selective removal of TiN films from Cr and Cu sacrificial layers under different conditions. The machining of TiN from (100) silicon showed relatively poor definition of patterned features. The analysis of these results indicated that laser machining of TiN from Cr and Cu layers is best explained using the explosion mechanism of removal.

Hybrid devices based on wholly bio-organic systems being interfaced with wholly inorganic systems are now being conceived of and constructed. A hypothetical device is likely to have some dynamic attributes and its dimensions will optimally be comparable with those of the current state of the art in microfabrication. While there are many established methods for interrogating the organic system in the laboratory, and thus extract information, few of those are compatible with micro/nano-technological integration. If magnetic dipoles can be incorporated into the biosystem, then there are a number of methods for non-intrusive interrogation (i.e. compatible with device functionality). Several such methods are discussed, and typical signal strengths are estimated for generic configurations. The most promising avenues arise either from detection of multiple parallel events, or from deployment of a scaled-down version of the well known vibrating loop method.

The carbon nanocoil is an interesting kind of nanomaterial, which is expected to have various novel applications in microelectronics, microelectromechanical systems (MEMS) and bioMEMS due to its nanosize coil morphology. Carbon nanocoils were synthesized by catalytic pyrolysis of acetylene over 2.2–3.0 µm Ni particles at 600°C in a microwave chemical vapour deposition (CVD) system. Microwave CVD derived nanocoils are rather uniform with an average coil diameter of 110–170 nm, fibre diameter of 80–120 nm and pitch of around 130–200 nm. The effects of reaction temperature, the size of Ni catalyst and the flow rate of acetylene were examined. Additionally, the growth mechanism of carbon nanocoils was studied. It was found that two individual carbon nanocoils extrude from the same Ni particle in the same direction as straight fibres at the beginning and then bend to grow into nanocoils in opposite directions.

We describe progress in nanofabrication processes for the production of silicon-based quantum computer devices. The processes are based on single-ion implantation to place phosphorus-31 atoms in accurate locations, precisely self-aligned to metal control gates. These fabrication schemes involve multi-layer resist and metal structures, electron beam lithography and multi-angled aluminium shadow evaporation. The key feature of all fabrication schemes is an integrated combination of patterns in different resist and metal layers that together define self-aligning metal gate structures as well as channels down to the substrate through which to implant the phosphorus. Central to this process is a new technique that allows for control and detection of the implantation process at a single-ion level.

Recognition of the potentially massive computational power of a quantum computer has driven a considerable experimental effort to build such a device. Of the various possible physical implementations, silicon-based architectures are attractive for the long spin relaxation times involved, their scalability, and ease of integration with existing silicon technology. However, their fabrication requires construction at the atomic scale—an immense technological challenge. Here we outline a detailed strategy for the construction of a phosphorus in silicon quantum computer and demonstrate the first significant step towards this goal—the fabrication of atomically precise arrays of single phosphorus bearing molecules on a silicon surface. After using a monolayer hydrogen resist to passivate a silicon surface we apply pulsed voltages to a scanning tunnelling microscope tip to selectively desorb individual hydrogen atoms with atomic resolution. Exposure of this surface to the phosphorus precursor phosphine results in precise placement of single phosphorus atoms on the surface. We also describe preliminary studies into a process to incorporate these surface phosphorus atoms into the silicon crystal at the array sites.

Single-spin detection will be crucial for solid-state quantum computer (QC) architectures in which information is encoded in the spin state of single nuclear or electron spins. The formidable problem of single-spin detection in a solid can be mapped to a more tractable problem of single-charge detection through spin-dependent electron transfer which may be observed using ultrasensitive solid-state nanostructure electrometers. Here we describe a read-out architecture using single-electron transistors (SETs) that can detect the charge state of two coupled metal dots, which simulates charge transfer in a two-quantum-bit (qubit) spin system. This twin-SET architecture allows significant reduction of random charge noise by correlating two detector outputs, reducing the probability of read-out errors in the QC.

The goal of this research is to improve the modular stability and programmability of DNA-based computers and is a second step towards optical programmable DNA computing. The main focus here is on hydrodynamic stability. Clockable microreactors can be connected in various ways to solve combinatorial optimization problems, such as maximum clique or 3-SAT. This work demonstrates by construction how one microreactor design can be programmed to solve any instance of maximum clique up to its given maximum size (N). It reports on an implementation of the architecture proposed previously (McCaskill J S 2001 Biosystems59 125–38). This contrasts with conventional DNA computing where the individual sequence of biochemical operations depends on the specific problem. In this pilot study we are tackling a graph for the maximum clique problem with N ≤ 12, with a special emphasis on N = 6. Furthermore, the design of the DNA solution space will be presented, which is symbolized by a set of bit-strings (words).

Two-dimensional arrays of vertical quantum wire Esaki tunnel diodes, laterally connected to their nearest neighbors by resistive/capacitive connections, constitute a powerful and versatile neuromorphic architecture that can function as classical Boolean logic circuits, associative memory, image processors, and combinatorial optimizers. In this paper, we discuss the basic philosophy behind adopting this architecture for nanoelectronic circuits and report on our experimental progress towards synthesizing this system.

A simulation of the interaction between atomic force microscope tips and protein surfaces employing the concept of the Connolly molecular surface with a carbon probe has been investigated. A methodology has been developed to allow the computation of the Connolly surface for a protein, where numerous atoms are simultaneously interacting with each other. The van der Waals and electrostatic interactions between the probe and the relevant Connolly surface elements are integrated to obtain the total interaction, resulting in precise theoretical accounts for a variety of interaction components.

A novel approach has been developed to obtain surface properties of a protein to give a better interpretation of the surface related phenomena, in particular protein attachment on polymer surface. This is achieved by extending the concept of molecular surface to find out relevant surface characteristics determining the interaction behaviour. The Connolly molecular surface is useful in the modelling and computation of surface properties, which could be of fundamental importance to surface-based protein science and engineering. A methodology for obtaining electron charge, hydrophobicity as well as α-helix and β-sheet structural indices has been developed.

Microarray technology is playing an increasingly important role in biology and medicine and its application to genomics for gene expression analysis has already reached the market with a variety of commercially available instruments. In these combinatorial analysis methods, known probe single-strand DNA (ssDNA) 'primers' are attached in clusters of typically 100 µm × 100 µm pixels. Each pixel of the array has a slightly different sequence. On exposure to 'unknown' target ssDNA, the pixels with the right complementary probe ssDNA sequence convert to double-stranded DNA (dsDNA) by a hybridization reaction. To transduct the conversion of the pixel to dsDNA, the target ssDNA is labelled with a photoluminescent tag during the polymerase chain reaction (PCR) amplification process. Due to the statistical distribution of the tags in the target ssDNA, it becomes significantly difficult to implement these methods as a diagnostic tool in a pathology laboratory. A method to sequence DNA without tagging the molecule is developed. The fabrication process is compatible with current microelectronics and (emerging) soft-material fabrication technologies, allowing the method to be integrable with micro-electromechanical systems (MEMS) and lab-on-a-chip devices. An estimated sensitivity of 10⁻¹² g on a 1 cm² device area is obtained.

The chemical binding of oligonucleotide/DNA on polystyrene-related polymeric surfaces has been investigated using contact angle measurements, x-ray photoelectron spectroscopy and gravimetric analysis. The results of the covalent attachment of the phosphorylated oligonucleotides using the hetero-bifunctional cross linker 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride to polystyrene-co-maleic anhydride (PSMAA) and polystyrene-co-maleic acid (PSMA) are described. The immobilization efficiency of covalently coupled 26-mer oligonucleotides to polymeric surfaces was estimated as 0.3 × 10¹⁰ and 0.1 × 10⁹ molecules mm⁻² for PSMA and PSMAA, respectively. The results suggest that, although the covalent binding on PSMAA per se is not capable of the high density of DNA required by micro-PCR applications, the method has the potential to be used as a cheap alternative for other low-cost, less DNA-sensitive applications such as disposable biosensors.

We demonstrate here a new method to control the location of cells on surfaces in two dimensions, which can be applied to a number of biomedical applications including diagnostic tests and tissue engineered medical devices. Two-dimensional control over cell attachment is achieved by generation of a spatially controlled surface chemistry that allows control over protein adsorption, a process which mediates cell attachment. Here, we describe the deposition of thin allylamine plasma polymer coatings on silicon wafer and perfluorinated poly(ethylene-co-propylene) substrates, followed by grafting of a protein resistant layer of poly(ethylene oxide). Spatially controlled patterning of the surface chemistry was achieved in a fast, one-step procedure by nanometer thickness controlled laser ablation using a 248 nm excimer laser. X-ray photoelectron spectroscopy and atomic force microscopy were used to confirm the production of surface chemistry patterns with a resolution of approximately 1 µm, which is significantly below the dimensions of a single mammalian cell. Subsequent adsorption of the extracellular matrix proteins collagen I and fibronectin followed by cell culture experiments using bovine corneal epithelial cells confirmed that cell attachment is controlled by the surface chemistry pattern. The method is an effective tool for use in a number of in vitro and in vivo applications.

Two well known, biologically inspired non-dynamical models of stochastic resonance, the threshold-crossing model and the fluctuating rate model, are analyzed in terms of channel information capacity and dissipation of energy necessary for small-signal transduction. Using analogies to spike propagation in neurons we postulate the average output pulse rate as a measure of dissipation. The dissipation increases monotonically with the input noise. We find that for small dissipation both models give a close to linear dependence of the channel information capacity on dissipation. In both models the channel information capacity, as a function of dissipation, has a maximum at input noise amplitude that is different from that in the standard signal-to-noise ratio versus input noise plot. Though a direct comparison is not straightforward, for small signals the threshold model gives appreciably higher density of information per dissipation than the exponential fluctuating rate model. We show that a formal introduction of cooperativity in the rate fluctuating model permits us to imitate the response function of the threshold model and to enhance performance. This finding may have direct relevance to real neural spike generation where, due to a strong positive feedback, the ion channel currents add up in a synchronized way.

A growing field of application for micro-electromechanical systems is the medical field of minimally invasive interventions. These procedures use catheters and guide wires, inserted into the blood vessels, to reach places deep inside the body, without the need for open surgery. This reduces recovery time and discomfort to the patient, operating time and the risks involved with general anaesthetics. For proper diagnosis and monitoring treatment, more information is needed; silicon sensors for catheters and guide wires have been developed to obtain this information. As the accurate positioning of these instruments is problematic, it is desirable to combine several sensors on the same instrument to measure several parameters at the same location. However, there are many considerations in designing silicon sensors for this application, such as small size, low power consumption, biocompatibility of materials, patient safety, a limited number of connections, packaging, survivability of the sensor during use, etc. This paper will discuss the design considerations of micromachined (silicon) sensors and actuators for use in catheters and guide wires. As an example, a multiparameter blood sensor, measuring flow velocity, pressure and oxygen saturation, will be discussed.

The purpose of this paper is to give an overview of different implant surface modification technologies—including the presentation of a new technique, involving the formation of a ceramic titanium oxide coating.

Three techniques are used to modify metal surfaces: (1) addition of material, (2) removal of material and (3) modification of material already present, e.g. by means of laser or electron-beam thermal treatment.

The new technique outlined in this paper relates to the production of a corrosion-resistant, 2000–2500 Å thick, ceramic oxide layer with a consistent crystalline structure on the surface of a titanium implant. The layer is grown electrochemically from the bulk of the metal and modified by heat treatment. Such ceramic oxide-coated implants have advantageous properties compared to implants covered with other coatings: a higher external hardness; a greater force of adhesion between the titanium and the ceramic oxide coating; virtually perfect insulation between an organism and a metal and therefore no possibility of triggering metal allergy. Plates and screws for maxillofacial osteosynthesis and dental root implants with ceramic oxide coatings were subjected to various physical, chemical and electron microscope tests for qualitative characterization, and have been applied in surgical practice over a period of 15 years. The mini-plates removed were examined for the possible surface alterations which may occur during the implantation period. The sites of the removal were inspected for metallosis, which is common when titanium mini-plates are used.

The results obtained demonstrate the good properties of the ceramic oxide-coated implants.

The surface morphology of machined screw-shaped titanium dental implants was modified by pulsed irradiation with an Nd glass laser. This method supplied very different surface elements in nanometer and micrometer ranges identified with scanning electron microscopy and atomic force microscopy as well. The surface composition was unchanged during these treatments. A rabbit experiment was carried out to investigate the direct bone contact (osseointegration) which was characterized by the removal torque of the implants. The 50 nm and 10–50 µm sized droplike elements were formed from the machined flat surface by the laser irradiation depending on the laser intensity. The osseointegration was enhanced by the increase of the density of nanosized elements and by the size of the microsized elements, showing the importance of this surface morphology in the direct bone–implant contact.

It is a great pleasure to introduce this special issue on BioMEMS and Smart Nanostructures.

Since the dawn of the electronic age, humanity has been achieving more efficient ways of controlling things, even remotely. The use of computers has made the control more straightforward and intelligent. Today, the level of control gets down to nanoscale dimensions and to the properties and response of materials and structures. Smart materials and structures provide control at low levels in the structure, similar to that in biologically inspired systems. This topic is very interdisciplinary and the research needs a multi-task approach and a clear vision of the physical processes behind the governing phenomena.

What you have in your hand is the result of an experiment. In this special issue, authors from the frontiers of physics, materials science, medicine, electrical engineering and optical engineering are presenting their pioneering methods and results. You can see general efforts toward making a smarter control. The way to achieve that is to make smarter sensors, actuators, electronics, materials, structures and computers.

Just like the whole field of smart materials and structures, the subjects in this issue are also strongly interdisciplinary and, among others, include materials science, MEMS science, medical science, quantum computing, neural science, etc.

We hope you will find the presented thoughts and results inspiring when you read this issue.