Current and speed control of a series-wound DC motor for an oil-well drill-string draw-works hoist drive

U ovome radu projektirani su i simulacijski ispitani PI regulator struje armature i PI regulator brzine vrtnje pogonskog motora dizalice naftnog bušećeg vretena, gdje je u ulozi pogonskog motora korišten istosmjerni motor sa serijskom uzbudom. Pri projektiranju PI regulatora struje armature kompenzacija protu-djelovanja elektromotorne sile ostvarena je pomoću estimatora elektromotorne sile, koji rekonstruira elektromotornu silu na temelju poznatih parametara i strukture modela armature motora, mjernog signala struje armature i reference napona. Koristeći estimiranu elektromotornu silu i poznavajući karakteristiku magnetiziranja motora, projektiran je estimator brzine vrtnje koji rekonstruira brzinu vrtnje motora, te zamjenjuje senzor brzine vrtnje u povratnoj vezi PI regulatoru brzine vrtnje motora. Parametri PI regulatora struje armature određeni su prema tehničkom optimumu, pri čemu se vremenska konstanta armature pokraćuje vremenskom konstantom PI regulatora struje, a zatim se pojačanje regulatora određuje primjenom kriterija optimuma dvostrukog odnosa s ciljem postizanja faktora prigušenja zatvorenog regulacijskog kruga = 0.707. Pri sintezi PI regulatora brzine vrtnje motora također je korišten optimum dvostrukog odnosa, ali dodatno uzimajući u obzir učinke elastičnosti prijenosnog mehanizma (prvenstveno čeličnog užeta dizalice). Simulacijski model reguliranog elektromotornog pogona dizalice izgrađen je i ispitan u programskom paketu MATLAB/SIMULINK™

Human mitochondrial ribosomes can switch structural tRNAs - but when and why?

High resolution cryoEM of mammalian mitoribosomes revealed the unexpected presence of mitochondrially encoded tRNA as a structural component of mitochondrial large ribosomal subunit (mt-LSU). Our previously published data identified that only mitochondrial (mt-) tRNA(Phe) and mt-tRNA(Val) can be incorporated into mammalian mt-LSU and within an organism there is no evidence of tissue specific variation. When mt-tRNA(Val) is limiting, human mitoribosomes can integrate mt-tRNA(Phe) instead to generate a translationally competent monosome. Here we discuss the possible reasons for and consequences of the observed plasticity of the structural mt-tRNA integration. We also indicate potential direction for further research that could help our understanding of the mechanistic and evolutionary aspects of this unprecedented system.This work was supported by the Wellcome Trust under Grant 096919/Z/11/Z and Medical Research Council UK under Grant MC_U105697135

Regulacija struje i brzine vrtnje istosmjernog motora sa serijskom uzbudom za pogon dizalice naftnog bušaćeg vretena

U ovome radu projektirani su i simulacijski ispitani PI regulator struje armature i PI regulator brzine vrtnje pogonskog motora dizalice naftnog bušećeg vretena, gdje je u ulozi pogonskog motora korišten istosmjerni motor sa serijskom uzbudom. Pri projektiranju PI regulatora struje armature kompenzacija protu-djelovanja elektromotorne sile ostvarena je pomoću estimatora elektromotorne sile, koji rekonstruira elektromotornu silu na temelju poznatih parametara i strukture modela armature motora, mjernog signala struje armature i reference napona. Koristeći estimiranu elektromotornu silu i poznavajući karakteristiku magnetiziranja motora, projektiran je estimator brzine vrtnje koji rekonstruira brzinu vrtnje motora, te zamjenjuje senzor brzine vrtnje u povratnoj vezi PI regulatoru brzine vrtnje motora. Parametri PI regulatora struje armature određeni su prema tehničkom optimumu, pri čemu se vremenska konstanta armature pokraćuje vremenskom konstantom PI regulatora struje, a zatim se pojačanje regulatora određuje primjenom kriterija optimuma dvostrukog odnosa s ciljem postizanja faktora prigušenja zatvorenog regulacijskog kruga = 0.707. Pri sintezi PI regulatora brzine vrtnje motora također je korišten optimum dvostrukog odnosa, ali dodatno uzimajući u obzir učinke elastičnosti prijenosnog mehanizma (prvenstveno čeličnog užeta dizalice). Simulacijski model reguliranog elektromotornog pogona dizalice izgrađen je i ispitan u programskom paketu MATLAB/SIMULINK™

Osjetljivo robotsko bušenje

U sklopu ovoga rada postavljen je i testiran u labaratorijskim uvijetima postav za osjetljivo robotsko bušenje. Postav se sastoji od nekoliko sustava: robotskog sustav Kuka Lightweight Robot LWR4+, sustava za očitanje sile i momenta ATI Net F/T sa mjernim osjetnikom „Gamma“, sustava namjenjenog za bušenje u medicini proizvođača Medtronic, te osobnog računala (PC-a). Na osobnome računalu programski jezik C++ (cpp) u sklopu programskoga paketa Microsoft Visual Studio 2010, simultano izvršavajući više programskih kodova (eng. multithreading) održava komunikacijske veze unutar postava, te PI regulator upravljačkom posmičnom brzinom svrdla održava silu pritiska svrdla tijekom bušenja konstantnom. Detekcija proboja bušenoga materijala odvija se izvršavanjem algoritma osjetljivoga na pad sile pritiska svrdla prilikom bušenja, na temelju postavljenih vrijednosnih pragova (eng. threshhold). Postav je testiran bušeći homogeni materijal (Al lim), umjetnu nehomogenu strukturu (Al lim – eps – Al lim), te teleću lopatičnu kost

Force sensitive robot drilling

U sklopu ovoga rada postavljen je i testiran u labaratorijskim uvijetima postav za osjetljivo robotsko bušenje. Postav se sastoji od nekoliko sustava: robotskog sustav Kuka Lightweight Robot LWR4+, sustava za očitanje sile i momenta ATI Net F/T sa mjernim osjetnikom „Gamma“, sustava namjenjenog za bušenje u medicini proizvođača Medtronic, te osobnog računala (PC-a). Na osobnome računalu programski jezik C++ (cpp) u sklopu programskoga paketa Microsoft Visual Studio 2010, simultano izvršavajući više programskih kodova (eng. multithreading) održava komunikacijske veze unutar postava, te PI regulator upravljačkom posmičnom brzinom svrdla održava silu pritiska svrdla tijekom bušenja konstantnom. Detekcija proboja bušenoga materijala odvija se izvršavanjem algoritma osjetljivoga na pad sile pritiska svrdla prilikom bušenja, na temelju postavljenih vrijednosnih pragova (eng. threshhold). Postav je testiran bušeći homogeni materijal (Al lim), umjetnu nehomogenu strukturu (Al lim – eps – Al lim), te teleću lopatičnu kost.Within this work, a predetermined robotic drilling pattern was set up and tested in laboratory conditions. The set consists of several systems: Lightweight Robot LWR4 + Robotic System, Network Force/Torque Sensor System with Gamma sensor, Medtronic Drill System, and personal computer (PC). On a personal computer, C ++ (cpp) programming language within the Microsoft Visual Studio 2010 program package, simultaneously executing multiple program codes (multithreading), maintains communication within the setup, and the PI controller with feed rate maintains the force of the drill bit during drilling constant. Detection of breakthrough is performed by performing a drilling bit-sensitive thrust force algorithm based on the set threshold. The installation was tested by drilling a homogeneous material (Al sheet), an artificial inhomogeneous structure (Al sheet - eps - Al sheet), and a calf bone

Macropinocytotic entry of isolated mitochondria in epidermal growth factor-activated human osteosarcoma cells

Mammalian mitochondria can be transferred between cells both in culture and in vivo. There is evidence that isolated mitochondria enter cells by endocytosis, but the mechanism has not been fully characterised. We investigated the entry mechanism of isolated mitochondria into human osteosarcoma (HOS) cells. Initially we confirmed that respiratory-competent cells can be produced following incubation of HOS cells lacking mitochondrial DNA (mtDNA) with functional exogenous mitochondria and selection in a restrictive medium. Treatment of HOS cells with inhibitors of different endocytic pathways suggest that uptake of EGFP-labelled mitochondria occurs via an actin-dependent endocytic pathway which is consistent with macropinocytosis. We later utilised time-lapse microscopy to show that internalised mitochondria were found in large, motile cellular vesicles. Finally, we used confocal imaging to show that EGFP-labelled mitochondria colocalise with a macropinocytic cargo molecule during internalisation, HOS cells produce membrane ruffles interacting with external mitochondria during uptake and EGFP-labelled mitochondria are found within early macropinosomes inside cells. In conclusion our results are consistent with isolated mitochondria being internalised by macropinocytosis in HOS cells.This work was supported by a grant from the Medical Research Council UK (MC_U105697135). We are grateful to Folma Buss for very helpful discussions during the course of this wo

Mitochondrially targeted ZFNs for selective degradation of pathogenic mitochondrial genomes bearing large‐scale deletions or point mutations

We designed and engineered mitochondrially targeted obligate heterodimeric zinc finger nucleases (mtZFNs) for site‐specific elimination of pathogenic human mitochondrial DNA (mtDNA). We used mtZFNs to target and cleave mtDNA harbouring the m.8993T>G point mutation associated with neuropathy, ataxia, retinitis pigmentosa (NARP) and the “common deletion” (CD), a 4977‐bp repeat‐flanked deletion associated with adult‐onset chronic progressive external ophthalmoplegia and, less frequently, Kearns‐Sayre and Pearson's marrow pancreas syndromes. Expression of mtZFNs led to a reduction in mutant mtDNA haplotype load, and subsequent repopulation of wild‐type mtDNA restored mitochondrial respiratory function in a CD cybrid cell model. This study constitutes proof‐of‐principle that, through heteroplasmy manipulation, delivery of site‐specific nuclease activity to mitochondria can alleviate a severe biochemical phenotype in primary mitochondrial disease arising from deleted mtDNA species

MRM2 and MRM3 are involved in biogenesis of the large subunit of the mitochondrial ribosome

Defects of the translation apparatus in human mitochondria are known to cause disease, yet details of how protein synthesis is regulated in this organelle remain to be unveiled. Ribosome production in all organisms studied thus far entails a complex, multistep pathway involving a number of auxiliary factors. This includes several RNA processing and modification steps required for correct rRNA maturation. Little is known about the maturation of human mitochondrial 16S rRNA and its role in biogenesis of the mitoribosome. Here we investigate two methyltransferases, MRM2 (also known as RRMJ2, encoded by FTSJ2) and MRM3 (also known as RMTL1, encoded by RNMTL1), that are responsible for modification of nucleotides of the 16S rRNA A-loop, an essential component of the peptidyl transferase center. Our studies show that inactivation of MRM2 or MRM3 in human cells by RNA interference results in respiratory incompetence as a consequence of diminished mitochondrial translation. Ineffective translation in MRM2- and MRM3-depleted cells results from aberrant assembly of the large subunit of the mitochondrial ribosome (mt-LSU). Our findings show that MRM2 and MRM3 are human mitochondrial methyltransferases involved in the modification of 16S rRNA and are important factors for the biogenesis and function of the large subunit of the mitochondrial ribosome

Human Cytomegalovirus Infection Upregulates the Mitochondrial Transcription and Translation Machineries.

UNLABELLED: Infection with human cytomegalovirus (HCMV) profoundly affects cellular metabolism. Like in tumor cells, HCMV infection increases glycolysis, and glucose carbon is shifted from the mitochondrial tricarboxylic acid cycle to the biosynthesis of fatty acids. However, unlike in many tumor cells, where aerobic glycolysis is accompanied by suppression of mitochondrial oxidative phosphorylation, HCMV induces mitochondrial biogenesis and respiration. Here, we affinity purified mitochondria and used quantitative mass spectrometry to determine how the mitochondrial proteome changes upon HCMV infection. We found that the mitochondrial transcription and translation systems are induced early during the viral replication cycle. Specifically, proteins involved in biogenesis of the mitochondrial ribosome were highly upregulated by HCMV infection. Inhibition of mitochondrial translation with chloramphenicol or knockdown of HCMV-induced ribosome biogenesis factor MRM3 abolished the HCMV-mediated increase in mitochondrially encoded proteins and significantly impaired viral growth under bioenergetically restricting conditions. Our findings demonstrate how HCMV manipulates mitochondrial biogenesis to support its replication. IMPORTANCE: Human cytomegalovirus (HCMV), a betaherpesvirus, is a leading cause of morbidity and mortality during congenital infection and among immunosuppressed individuals. HCMV infection significantly changes cellular metabolism. Akin to tumor cells, in HCMV-infected cells, glycolysis is increased and glucose carbon is shifted from the tricarboxylic acid cycle to fatty acid biosynthesis. However, unlike in tumor cells, HCMV induces mitochondrial biogenesis even under aerobic glycolysis. Here, we have affinity purified mitochondria and used quantitative mass spectrometry to determine how the mitochondrial proteome changes upon HCMV infection. We find that the mitochondrial transcription and translation systems are induced early during the viral replication cycle. Specifically, proteins involved in biogenesis of the mitochondrial ribosome were highly upregulated by HCMV infection. Inhibition of mitochondrial translation with chloramphenicol or knockdown of HCMV-induced ribosome biogenesis factor MRM3 abolished the HCMV-mediated increase in mitochondrially encoded proteins and significantly impaired viral growth. Our findings demonstrate how HCMV manipulates mitochondrial biogenesis to support its replication.S.K. was supported by a European Molecular Biology Organization long-term fellowship (ALTF 887-2009). M.P.W is funded by a Wellcome Trust Senior Clinical Fellowship (108070/Z/15/Z). R.J.S. is supported by MRC grant (MR/L008734/1). P.J.L . is supported by a Wellcome Trust Principal Research Fellowship, grant (WT101835). J. S. is supported by MRC Programme grant (G0701279). J.R., L. V. and M.M. are supported by MRC as part of the core funding for the Mitochondrial Biology Unit (MC_U105697135). L.V. is also supported by EMBO (ALFT 701- 2013).This is the final version of the article. It first appeared from the American Society for Microbiology via http://dx.doi.org/10.1128/mBio.00029-1

PDE12 removes mitochondrial RNA poly(A) tails and controls translation in human mitochondria

Polyadenylation of mRNA in human mitochondria is crucial for gene expression and perturbation of poly(A) tail length has been linked to a human neurodegenerative disease. Here we show that 2′-phosphodiesterase (2′-PDE), (hereafter PDE12), is a mitochondrial protein that specifically removes poly(A) extensions from mitochondrial mRNAs both in vitro and in mitochondria of cultured cells. In eukaryotes, poly(A) tails generally stabilize mature mRNAs, whereas in bacteria they increase mRNA turnover. In human mitochondria, the effects of increased PDE12 expression were transcript dependent. An excess of PDE12 led to an increase in the level of three mt-mRNAs (ND1, ND2 and CytB) and two (CO1 and CO2) were less abundant than in mitochondria of control cells and there was no appreciable effect on the steady-state level of the remainder of the mitochondrial transcripts. The alterations in poly(A) tail length accompanying elevated PDE12 expression were associated with severe inhibition of mitochondrial protein synthesis, and consequently respiratory incompetence. Therefore, we propose that mRNA poly(A) tails are important in regulating protein synthesis in human mitochondria, as it is the case for nuclear-encoded eukaryotic mRNA