Combined Micro Research Articles

Microstructure and tribological behavior of self-lubricating (Si:N)-DLC/MAO coatings on AZ80 magnesium substrate

The combined micro arc oxidation (MAO) and a hybrid beam deposition process was used to deposit duplex (Si:N)-DLC/MAO coatings on AZ80 magnesium alloy. The microstructure and composition of the duplex coatings were analyzed by Raman spectroscopy, X-ray photoelectron spectroscope (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM). Tribological behaviors of the coatings were studied by ball-on-disk friction test. It was found that the ID/IG ratio of the (Si:N)-DLC (diamond-like carbon) top films increases with decreasing C2H2/N2 ratio. The (Si:N)-DLC top film with Si3N4 was formed on the MAO coated sample as the C2H2/N2 ratio was 10sccm:5sccm, which showed an increasing critical load compared with the pure DLC directly deposited on the Mg alloy substrate. As a result, the (Si:N)-DLC/MAO coating exhibited an advanced wear protection for the substrate.

Research on Coal-Formed Gas Reservoir Combined Qualitative and Quantitative Methods

At present, coal is still the primacy of China's energy structure, and this situation will not change in a short time. Coal-formed Gas Reservoir quality and the predicting method have also become one of the urgent needs to address the issue of energy exploration, but the lateral variation of the coal-formed gas reservoir is a common geological phenomenon in the coal mine, if the prediction error is too large, it will greatly impact on the production of coal mine. Especially in the area where has complex structure characteristics, the reservoirs are impacted by structural changes, the reservoir predicting become the most important job and the most difficult job. This paper take the example of DaCheng, the research carried out the sedimentary reservoir characteristics, the coal body structure, the coal thickness, the heterogeneity of the coal seams and collapse columns of coal reservoir, and then reservoir fine evaluation was done combined Micro and Macro, Qualitative and Quantitative methods.

A New Family of Two‐Dimensional Zeolites Prepared from the Intermediate Layered Precursor IPC‐3P Obtained during the Synthesis of TUN Zeolite

The crystallization of zeolite TUN with 1,4-bis(N-methylpyrrolidinium)butane as template proceeds through an intermediate, designated IPC-3P, following the Ostwald rule of successive transformations. This apparently layered transient product has been thoroughly investigated and found to consist of MWW monolayers stacked without alignment in register, that is, disordered compared with MCM-22P. The structure was confirmed based on X-ray diffraction and high-resolution (HR)TEM analysis. The layered zeolite precursor IPC-3P can be swollen and pillared affording a combined micro- and mesoporous material with enhanced Brunauer-Emmett-Teller (BET) surface area (685 m(2) g(-1) ) and greater accessibility of Brønsted acid sites for bulky molecules. This mesoporous material was probed with 2,6-di-tert-butylpyridine (DTBP). IPC-3P and its modification create a new layered zeolite sub-family belonging to the MWW family. FTIR data indicate that (Al)MWW materials MCM-22 and IPC-3 with Si/Al ratios greater than 20 exhibit a lower relative ratio of Brønsted to Lewis acid sites than MCM-22 (with Si/Al ratios of around 13), that is, less than 2 versus more than 3, respectively. This is maintained even upon pillaring and warrants further exploration of materials like IPC-3P with a higher Al content. The unique XRD features of IPC-3P indicating misaligned stacking of layers and distinct from MCM-22P, are also seen in other MWW materials such as EMM-10P, hexamethonium-templated (HM)-MCM-22, ITQ-30, and UZM-8 suggesting the need for more detailed study of their identity and properties.

Constructal design of combined microchannel and micro pin fins for electronic cooling

This paper presents a three-dimensional numerical study of steady, laminar, incompressible flow and forced convection heat transfer through a microchannel heat sink with micro pin fin inserts for both fixed and variable axial lengths. The objective of the study was to optimise the geometric configuration of an integrated microchannel and micro pin fins for different solid volumes so that the peak temperature in the configuration was minimised. The effect of the micro pin fins on the optimised microchannel was also investigated. The geometric optimisation of the integrated microchannel and micro pin fin was carried out using a computational fluid dynamics (CFD) code with a goal-driven optimisation tool subject to global constraints. The optimisation procedure was carried out in two steps. Firstly, the microchannel configuration was optimised without the micro pin fins inserted and the results were compared with similar work found in the open literature. This optimisation was carried out for both fixed and relaxed lengths. Thereafter, the integrated design of the microchannel and micro pin fins was optimised. The effect of the Bejan number on the solid volume fraction, channel aspect ratio and hydraulic diameter, pin fin aspect ratio, minimised peak temperature and maximised thermal conductance were reported.Results showed that as the Bejan number increased, the minimised peak temperature decreased. Also, the maximum thermal conductance increased with the optimised microchannel structure with three to six rows of micro pin fin inserts. Diminishing return set in when the number of rows of micro pin fin inserts was greater than three for the fixed length but for the relaxed length, as the number of rows increased, the results improved but when it exceeded six diminishing returns set in for a fixed solid volume of 0.9mm3. For each Bejan number used in this study, there was an optimum channel hydraulic diameter and aspect ratio, solid volume fraction and pin fin aspect ratio that satisfied the global objective.

Catalytic decomposition and reduction of N2O over micro-mesoporous materials containing Beta zeolite nanoparticles

Zeolitic materials with combined micro and mesoporous structure were synthesized using two different approaches. A first series of the samples was obtained by impregnation method. Suspension of Beta nanoparticles was impregnated on SBA-15 mesoporous silica. In the second synthesis route, called non-templating method, Beta nanoparticles were aggregated under specified conditions with the formation of micro-mesoporous material (without the use of the mesopore directing agent). Micropores were present in the zeolite nanoparticles, while mesopores were located in the interparticle space. The combined micro and mesoporous structure of the obtained materials, exhibiting the properties of Beta zeolite, was confirmed by nitrogen sorption measurements, XRD, TGA and DRIFT techniques. The hierarchical porous structure of the samples resulted in an improved accessibility of ion-exchange positions in comparison to conventional Beta zeolite and allowed the introduction of iron, nearly exclusively in the form of monomeric Fe3+ cations and oligomeric FexOy species. The iron modified micro-mesoporous samples as well as SBA-15 and Beta zeolite (as reference samples), were tested as catalysts of N2O decomposition. The most promising micro-mesoporous sample (Fe-Beta/meso) was tested as catalyst in the reactions of N2O decomposition and N2O reduction with CO at different composition of gas mixture (in the presence of O2, H2O and NO). Catalytic activity of iron-exchanged, micro-mesoporous Beta and conventional Beta zeolites in the reaction of N2O conversion was very similar.

Semi‐quantitative analysis of the formation of a calcium oxalate protective layer for monumental limestone using combined micro‐XRF and micro‐XRPD

A current method for the protection of cretaceous limestone present in various monuments consists of performing a passivating treatment with ammonium oxalate (AmOx). A calcium oxalate protective layer is formed on the surface and enhances the acid resistance of the stone. The in‐depth formation of the calcium oxalate layer was investigated on cross sections by using combined micro X‐ray fluorescence and micro X‐ray powder diffraction (µXRF/µXRPD). XRPD showed the presence of both whewellite and weddellite in the calcite stone matrix. A correction was made for sample misalignment, which was visible in both the fluorescence and the diffraction line measurements. A semi‐quantitative analysis was performed on the basis of Klug's equation for a two‐phase mixture (the presence of weddellite was neglected) without the need for a known reference sample. By assuming two extreme compositions for a reference weight fraction (1 and 99 wt%), it was possible to obtain whewellite concentration profiles, which can be used for comparing the effectiveness of different methods for the application of AmOx to the stone surface and the effect of treatment time and AmOx concentration used. It is shown that for the relative amounts of whewellite formed, the differences due to the assumed weight fractions are smaller than the errors due to sample heterogeneity and preferred orientation. Copyright © 2013 John Wiley & Sons, Ltd.

A combined electron probe micro analysis and scanning Kelvin probe force microscopy study of a modified AA4xxx/AA3xxx aluminium brazing sheet

The electrochemical and microstructural properties of the clad and core from a modified AA3xxx/AA4xxx brazing sheet were investigated before and after brazing. For this, scanning Kelvin probe force microscopy (SKPFM) and field emission electron probe micro analysis (FE-EPMA) were used. The Volta potential difference (VPD) was measured as a function of depth for the brazed and non-brazed sheets. This was correlated with the cross-sectional variation of chemistry and microstructure that result from brazing. Furthermore, potentiodynamic polarization experiments and subsequent microscopic analysis of the corroded samples were used to explore the corrosion mechanism of the modified brazed sheet. The investigation revealed that the major consequences of brazing for the microstructure are: an increase in the Si content of the matrix in the heat affected zone (HAZ); a non-uniform distribution of Cu in the HAZ; an accumulation of Cu in Al–Si eutectics and around the grain boundaries, including α-Al(Mn,Fe)Si and Al2Cu intermetallics; the presence of some continuous grain boundaries in both the clad and core of the sheet; and the non-uniform precipitation of intermetallics at Al–Si eutectic phases. The impact of these microstructural changes on the corrosion behaviour of the brazed sheet was: to increase the VPD of the re-solidified clad matrix; to introduce localized corrosion susceptibility on the brazed clad and core structures; and to reduce the cathodic protection power of the re-solidified clad material. As a result of the correlation between microstructure and electrochemical behaviour, it was concluded that corrosion resistance of the modified aluminium brazing sheet could be improved by applying a post-braze heat treatment.

Development of an optimized artificial neural network model for combined heat and power micro gas turbines

Micro gas turbines are considered an efficient alternative to costly generation and transmission of electricity, especially in remote areas and in combined heat and power (CHP) applications. Tools for remote monitoring and diagnostics, which are easy to apply, would be needed for the realization of distributed CHP. This paper reports the development of a validated artificial neural network (ANN) model for efficient and appropriate monitoring of a micro gas turbine. This study is based on experimental data obtained from a Turbec T100 micro gas turbine. The gas turbine test rig used in this study consists of a modified engine with extended measurement points providing extensive data suitable for data-driven modeling. ANNs, in contrast to mathematical models, do not require detailed and exact component characteristics, making them applicable for monitoring in many cases. The developed ANN model was based on a multi-layer feed forward network with back-propagation algorithm. Relations between the inputs and outputs of an ANN model are not implemented by physical equations but are built up during the training process. Thus, a systematic sensitivity analysis, conducted in several steps, was performed to investigate the dependency between initially selected input and output parameters. Based on sensitivity analysis results, the “optimized” set of input parameters and final outputs were concluded, taking into account prediction accuracy. The procedure of the ANN model development and sensitivity analysis are discussed in detail. The mean relative error (MRE) was used to evaluate the prediction accuracy of the developed networks with respect to experimental data which were not used during the training. The prediction results showed that the final optimum ANN model can serve as an accurate baseline model for monitoring applications.

Effect of composite electrode microstructure on temperature distribution in solid oxide fuel cells

Temperature distributions in the solid structure of planar solid oxide fuel cells with various microstructures of composite electrodes are studied through the combined micro and macro cell modeling. The results of the computer simulation reveal that the composite electrode microstructure can play a significant role in the mean temperature, temperature difference between the hottest and coldest spots, and maximum temperature gradient in the solid structure of the cell. The variation of these three parameters at different electrodes microstructural variables – including porosity, thickness, particle size ratio, and the size and volume fraction of particles – is quantified in this article.

The Macroprudential Turn: From Institutional 'Safety and Soundness' to Systemic 'Financial Stability' in Financial Supervision

Since the global financial dramas of 2008-09, authorities on financial regulation have come increasingly to counsel the inclusion of macroprudential policy instruments in the standard ‘toolkit’ of finance-regulatory measures employed by financial supervisors. The hallmark of this perspective is its focus not simply on the safety and soundness of individual financial institutions, as is characteristic of the traditional ‘microprudential’ perspective, but also on certain structural features of financial systems that can imperil such systems as wholes. Systemic ‘financial stability’ thus comes to supplement, though not to supplant, institutional ‘safety and soundness’ as a regulatory desideratum. The move from primarily micro- to combined micro- and macroprudential finance-regulatory regimes is surely to be welcomed, for reasons that this author and others have offered in earlier articles. The old ‘lean versus clean’ debate is resolved once again now in favor of leaning. The victory does, however, raise certain new legal challenges to which predominantly microprudential finance-regulatory regimes are not typically subject – challenges of which regulators and other financially-oriented lawyers will wish to stay mindful. This Article aims to respond to that wish by comprehensively cataloguing and provisionally addressing the mentioned challenges, in order that interested parties might thereby be able to find full treatment of the subject in one place.

Study and Application on Ultrasonical Combined Electrical Micro-Machining the Special Shape Micro-Structures

For manufacturing the special shape micro-structures with hard and brittle materials , the ultrosonical combined electrical micro-machining method is proposed and improved. The ultrasonical combined synchronous electrochemical micro-machining system is built and optimized, which machining parameters can be adjusted in a big ranges, and the synchronous target between the ultrasonical vibration and the voltage of micro-PECM(Micro-pulse electrochemical machining) can be realized. The micro-machining electrodes are manufactured in round sections by combined micro electrical-discharged machining (EDM).The mechanism tests of ultrasonic vibration combined electrical pulse micro-machining tests are carried. It is adopted that the low amplitude of electrical voltage (no more than 6V) and the static electrolyte with lower electrical conduction rate, the good machining accuracy and surface quality are acquired. The regular morphology array micro-round holes are manufactured successfully on friction units' working surface, which can save oil , improve the friction performances and prolonging working life of important friction units. In additional, the fixed holes satisfying the precision needs are machined on the hard and brittle piezo-ceramics pieces, which are often used in many important micro-precise piezo-ceramics sensor. It is proved that ultrasonic combined electrical micro-machining is an effect method for to machine the special shape micro-structures.

Investigating Micro Spherical Stylus Tips Fabrication by Electro Chemical and Single Pulse Electro Discharge Processes

M icro spherical stylus tip plays an important role in micro coordinate measuring machine (CMM) metrology. A micro CM M needs a tiny spherical stylus tip with diameter less than 0.125mm to measure micro components such as micro slots, micro holes, and micro gears. With combination WEDG technology and one pulse electro discharge (OPED) process, micro spherical stylus tips with 60μm in diameter has been fabricated successfully. However the time consuming of a long micro electrode tool fabrication is still a critical problem by WEDG technology. In order to fabricate micro ball-ended stylus tips more efficiency, this study presents a new hybrid process with combination micro ECM and OPED to produce micro spherical sty lus tips for micro CMM's probing heads. To fabricate high quality spherical stylus tips, the parameters of micro ECM and OPED such as feeding speed, concentration of electrolyte, and pulse duration will be also investigated in this study. It is expected that micro spherical stylus for CMM's probing heads could be fabricated more efficiency by this hybrid machining process.

C-terminal protein characterization by mass spectrometry using combined micro scale liquid and solid-phase derivatization.

A sample preparation method for protein C-terminal peptide isolation has been developed. In this strategy, protein carboxylate glycinamidation was preceded by carboxyamidomethylation and optional α- and ϵ-amine acetylation in a one-pot reaction, followed by tryptic digestion of the modified protein. The digest was adsorbed on ZipTip(C18) pipette tips for sequential peptide α- and ϵ-amine acetylation and 1-ethyl-(3-dimethylaminopropyl) carbodiimide-mediated carboxylate condensation with ethylenediamine. Amino group-functionalized peptides were scavenged on N-hydroxysuccinimide-activated agarose, leaving the C-terminal peptide in the flow-through fraction. The use of reversed-phase supports as a venue for peptide derivatization enabled facile optimization of the individual reaction steps for throughput and completeness of reaction. Reagents were exchanged directly on the support, eliminating sample transfer between the reaction steps. By this sequence of solid-phase reactions, the C-terminal peptide could be uniquely recognized in mass spectra of unfractionated digests of moderate complexity. The use of the sample preparation method was demonstrated with low-level amounts of a model protein. The C-terminal peptides were selectively retrieved from the affinity support and proved highly suitable for structural characterization by collisionally induced dissociation. The sample preparation method provides for robustness and simplicity of operation using standard equipment readily available in most biological laboratories and is expected to be readily expanded to gel-separated proteins.

Remission rate after transsphenoidal surgery in patients with pathologically confirmed Cushing’s disease, the role of cortisol, ACTH assessment and immediate reoperation: a large single center experience

Postoperative serum cortisol is used as an indicator of Cushing's disease (CD) remission following transsphenoidal surgery (TSS) and guides (controversially) the need for immediate adjuvant treatment for CD. We investigated postoperative cortisol and adrenocorticotropic hormone (ACTH) levels as predictors of remission/recurrence in CD in a large retrospective cohort of patients with pathologically confirmed CD, over 6 years at a single institution. Midnight and morning cortisol, and ACTH at 24-48 h postoperatively (>24 h after last hydrocortisone dose) were measured. Remission was defined as normal 24-h urine free cortisol, normal midnight salivary cortisol, a normal dexamethasone-corticotropin releasing hormone (CRH) test or continued need for hydrocortisone, assessed periodically. Statistical analysis was performed using PASW 18. Follow up data was available for 52 patients (38 females and 14 males), median follow up was 16.5 month (range 2-143 months), median age was 45 years (range 21-72 years), 28 tumors were microadenomas and 16 were macroadenomas, and in eight cases no tumor was observed on magnetic resonance imaging. No patient with postoperative cortisol levels >10 mcg/dl were found to be in remission. Ten of the 52 patients with cortisol >10 mcg/dl by postoperative day 1-2 underwent a second TSS within 7 days. Forty-three patients (82.7%) achieved CD remission (36 after one TSS and 7 after a second early TSS) and six patients suffered disease recurrence (mean 39.2 ± 52.4 months). An immediate second TSS induced additional hormonal deficiencies (diabetes insipidus) in three patients with no surgical complications. Persistent disease was noted in nine patients despite three patients having an immediate second TSS. Positive predictive value for remission of cortisol <2 mcg/dl and ACTH <5 pg/ml was 100%. Cortisol and ACTH levels (at all postoperative time points and at 2 months) were correlated (r = 0.37, P < 0.001). Nadir serum cortisol of ≤2 mcg/dl and ACTH <5 pg/ml predicted remission (P < 0.005), but no level predicted lack of recurrence. Immediate postoperative ACTH/cortisol did not predict length of remission. No patients with postoperative cortisol >10 mcg/dl were observed to have delayed remission; all required additional treatment. There was no significant difference in age, body mass index, tumor size and length of follow-up between postoperative cortisol groups: cortisol ≤2 mcg/dl, cortisol >5 mcg/dl and cortisol >10 mcg/dl. Immediate postoperative cortisol levels should routinely be obtained in CD patients post TSS, until better tools to identify early remission are available. Immediate repeat TSS could be beneficial in patients with cortisol >10 mcg/dl and positive CD pathology: our combined (micro- and macroadenomas) remission rate with this approach was 82.7%. ACTH measurements correlate well with cortisol. However, because no single cortisol or ACTH cutoff value excludes all recurrences, patients require long-term clinical and biochemical follow-up. Further research is needed in this area.

Combined 3D Micro Structuring of Ceramic Green Tape Using Punching, Embossing and Laser Processing

Multilayer ceramics technology, as LTCC, offers several advantages for the fabrication of miniaturized three-dimensional structures, e.g. for microsystem applications, where electrical, mechanical and fluidic functions can be combined in robust and compact packages. 3D features, required by those applications, are e.g. vias for electrical and thermal interconnection, cavities for chip integration and channels for fluidic functions. They can be realized, in principle, in the sintered, as well as in the green state, but structuring in the green state dominates due to the then far better machinability of the material. Ceramic green tape structuring is usually accomplished by mechanical or laser machining. Punching is the standard process for realizing vias or cavities in LTCC. By nature, only through tape features can be realized, but 3D features can be realized by stacking of several layers. Embossing can be used for the realization of quite complex 3D structures with high resolution. It can be carried out either at elevated temperature, at which the binder of the tape is softened (hot embossing) or at room temperature (cold embossing). Laser structuring is a quite flexible method, which allows both through-cutting and engraving without any specific tool. However, a certain roughness of ablated areas cannot be avoided, and depth control and uniformity of laser engraved features remain challenging. In the present paper, the different techniques will be compared regarding their appropriateness for different structuring tasks. A combined use of punching, embossing and laser processing is described, which has been made possible by a novel machine and tool concept.

Superhydrophilic surface on Cu substrate to enhance lubricant retention

The loss of lubricant from the surfaces of critical machine parts often leads to friction and heat-related failures which can cause catastrophic damage to machinery. In this study, the effect of micro- and nano-texturing on lubricant retention was investigated. Micro-textures were produced by sandblasting Cu substrates, while nano-textures were created by aluminum-induced crystallization of amorphous silicon. The topography and the wettability of the textured surfaces were characterized by means of scanning electron microscopy and a video-based optical contact angle measuring system, respectively. The lubricant retention on the textured surfaces was investigated using a dynamic method. It was found that superhydrophilic surfaces created by the combined micro- and nano-texturing technique can significantly enhance the lubricant retention on Cu substrates.

Exposure to bisphenol A is associated with low-grade albuminuria in Chinese adults

Bisphenol A is an industrial chemical widely used in plastic products with a consequent exposure to humans. To assess whether exposure to bisphenol A is associated with renal disease, we searched for low-grade albuminuria in 3055 Chinese adults in the Shanghai metropolitan area aged 40 years or older. Using a value for urinary albumin-to-creatinine ratios <30 mg/g, we examined its association with urinary bisphenol A. Participants in the highest compared to the lowest quartile of urinary bisphenol A concentrations were significantly more likely to have low-grade albuminuria. Multivariate stepwise linear regression analysis, adjusted for potential confounding factors, showed that urinary bisphenol A was an independent determinant of the urinary albumin-to-creatinine ratio significantly associated with an increased risk of low-grade albuminuria with an adjusted odds ratio of 1.23 for the highest compared to the lowest concentration quartiles. This association was not modified by conventional risk factors such as age, gender, smoking, alcohol consumption, body mass index, hypertension, diabetes, and the estimated glomerular filtration rate. There was no significant relationship between bisphenol A and combined micro- and macroalbuminuria. Thus, our study lends support to a potential relation between bisphenol A exposure and an increased risk of low-grade albuminuria.

A micro–meso computational strategy for the prediction of the damage and failure of laminates

Laminated composites may undergo significant degradations prior to their ultimate failure. Even though these degradations are associated with length scales which are much smaller than the structural scale, their interactions may greatly influence global failure. Various approaches have been proposed to seek the best compromise between a detailed physical description and a reasonable computational cost. This paper presents a combined micro–meso computational strategy based on two existing models involving two different descriptions of the mechanisms on the ply’s scale (a discrete description and a homogenized continuous description). The coupling of the two models is achieved through a nonintrusive global–local strategy. In addition, a specific type of link is introduced, enabling one to choose the information to be transferred between the two scales. The coupled calculation enables one to evaluate the limitations of the homogenized mesoscale model and contributes to the determination of a more accurate and computationally efficient multiscale strategy.

Lumped modeling of carbon nanotubes for M/NEMS simulation

This paper presents a lumped model of a single walled carbon nanotube (CNT) using structural matrix mechanics. We implement the CNT model in Sugar and SugarCube to facilitate the design, modeling and simulation of combined micro and nano-scale systems. That is, where users can explore the application of CNTs as components of an electromechanical system. Our lumped CNT model is able to represent the dynamic response of a zigzag or armchair chirality, with the desired diameter, length, and distributed loading parameters. Our present dynamic CNT model is limited to small deflections and user-defined geometric properties. Our tools are accessible through the Web with remote computation at http://www.nanoHUB.org .

Transcriptional repression of the Dspp gene leads to dentinogenesis imperfecta phenotype in Col1a1-Trps1 transgenic mice

Dentinogenesis imperfecta (DGI) is a hereditary defect of dentin, a calcified tissue that is the most abundant component of teeth. Most commonly, DGI is manifested as a part of osteogenesis imperfecta (OI) or the phenotype is restricted to dental findings only. In the latter case, DGI is caused by mutations in the DSPP gene, which codes for dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). Although these two proteins together constitute the majority of noncollagenous proteins of the dentin, little is known about their transcriptional regulation. Here we demonstrate that mice overexpressing the Trps1 transcription factor (Col1a1-Trps1 mice) in dentin-producing cells, odontoblasts, present with severe defects of dentin formation that resemble DGI. Combined micro–computed tomography (µCT) and histological analyses revealed tooth fragility due to severe hypomineralization of dentin and a diminished dentin layer with irregular mineralization in Col1a1-Trps1 mice. Biochemical analyses of noncollagenous dentin matrix proteins demonstrated decreased levels of both DSP and DPP proteins in Col1a1-Trps1 mice. On the molecular level, we demonstrated that sustained high levels of Trps1 in odontoblasts lead to dramatic decrease of Dspp expression as a result of direct inhibition of the Dspp promoter by Trps1. During tooth development Trps1 is highly expressed in preodontoblasts, but in mature odontoblasts secreting matrix its expression significantly decreases, which suggests a Trps1 role in odontoblast development. In these studies we identified Trps1 as a potent inhibitor of Dspp expression and the subsequent mineralization of dentin. Thus, we provide novel insights into mechanisms of transcriptional dysregulation that leads to DGI. © 2012 American Society for Bone and Mineral Research.