The optimization of the acoustic silencer volume is very important to develop it and to get high-performance,the importance of the silencer was appeared in industrial field to eliminate the noise of the duct by effici...The optimization of the acoustic silencer volume is very important to develop it and to get high-performance,the importance of the silencer was appeared in industrial field to eliminate the noise of the duct by efficient and economical method.The main goal of this research is to optimize the transmission loss(TL)by analytical method of the Double-Chamber Silencer(DCS),the TL has been selected as the main parameter in silencer because it does not based on the source or the termination impedances.First we calculated the power transmission coefficient(PTC)and the TL of an acoustic silencer,then used the Lagrange method to optimize the silencer length.All calculation of silencer data is obtained by solving the governing equations in commercial software Matlab®.A several calculations for different silencer length at many frequency ranges were performed simultaneously.Finally,this research supports the efficient and rapid techniques for DCS optimal design under narrow space.The results show that the acoustic TL is maximized at the desired frequency.展开更多
The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage...The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage of structures, creating an environmental, social problem and also military problems such as exposure of location of troops. This high pressure impulsive sound, generated during the blast flow, was studied and attenuated. An axisymmetric computational domain was constructed by employing Spalart Allmaras turbulence model. Approximately 90% of pressure and 20 dB of sound level are reduced due to the use of the three baffle silencer at the muzzle end of the gun barrel, in comparison with the tank gun without silencer. Also, the sound pressure level at different points in the ambient region shows the same attenuation in results. This study will be helpful to understand the blast wave characteristics and also to get a good idea to design silencer for large caliber weapon system.展开更多
The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-...The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies.展开更多
The developmental stage-specific silencing of the human ε-globin gene during embryonic life is controlled, inpart, by the silencer (-392bp～-177bp) upstream of thisgene. In order to elucidate its role, the nuclear ex...The developmental stage-specific silencing of the human ε-globin gene during embryonic life is controlled, inpart, by the silencer (-392bp～-177bp) upstream of thisgene. In order to elucidate its role, the nuclear extractfrom the human fetal liver has been prepared and the interactions between trans-acting factors and this silencerelement have been examined. By using DNasel footprinting assay, a major protected region from -278bp to -235bpwithin this silencer element was identified. Furthermore,we found in gel mobility shift assay and Southwestern blotting assay that there were at least four trans-acting factors (MW ≈ 32, 28, 26 and 22kD) in the nuclear extractisolated from the human fetal liver, which could specifically bind to this region. Our results suggested that thesetrans-acting factors might play an important role in silencing the human embryonic ε-globin gene expression at thefetal stage through the interactions with this silencer.展开更多
In marine engine exhaust silencing systems, the presence of exhaust gas flow influences the sound propagation inside the systems and the acoustic attenuation performance of silencers. In order to investigate the effec...In marine engine exhaust silencing systems, the presence of exhaust gas flow influences the sound propagation inside the systems and the acoustic attenuation performance of silencers. In order to investigate the effects of three-dimensional gas flow and acoustic damping on the acoustic attenuation characteristics of marine engine exhaust silencers, a dual reciprocity boundary element method (DRBEM) was developed. The acoustic governing equation in three-dimensional potential flow was derived first, and then the DRBEM numerical procedure is given. Compared to the conventional boundary element method (CBEM), the DRBEM considers the second order terms of flow Mach number in the acoustic governing equation, so it is suitable for the cases with higher Mach number subsonic flow. For complex exhaust silencers, it is difficult to apply the single-domain boundary element method, so a substructure approach based on the dual reciprocity boundary element method is presented. The experiments for measuring transmission loss of silencers are conducted, and the experimental setup and measurements are explained. The transmission loss of a single expansion chamber silencer with extended inlet and outlet were predicted by DRBEM and compared with the measurements. The good agreements between predictions and measurements are observed, which demonstrated that the derived acoustic governing equation and the DRBEM numerical procedure in the present study are correct.展开更多
Timbre,as one of the essential elements of sound,plays an important role in determining sound properties,whereas its manipulation has been remaining challenging for passive mechanical systems due to the intrinsic disp...Timbre,as one of the essential elements of sound,plays an important role in determining sound properties,whereas its manipulation has been remaining challenging for passive mechanical systems due to the intrinsic dispersion nature of resonances.Here,we present a meta-silencer supporting intensive mode density as well as highly tunable intrinsic loss and offering a fresh pathway for designable timbre in broadband.Strong global coupling is induced by intensive mode density and delicately modulated with the guidance of the theoretical model,which efficiently suppresses the resonance dispersion and provides desirable frequency-selective wave-manipulation capacity for timbre tuning.As proof-of-concept demonstrations for our design concepts,we propose three meta-silencers with the designing targets of high-efficiency broadband sound attenuation,efficiency-controlled sound attenuation and designable timbre,respectively.The proposed meta-silencers all operate in a broadband frequency range from 500 to 3200 Hz and feature deep-subwavelength sizes around 50 mm.Our work opens up a fundamental avenue to manipulate the timbre with passive resonances-controlled acoustic metamaterials and may inspire the development of novel multifunctional devices in noise-control engineering,impedance engineering,and architectural acoustics.展开更多
Acoustic performance of dissipative silencer was evaluated to determine the effectiveness of perforated duct porosity and absorbent material density in reducing occupational noise exposure propagated from centrifugal ...Acoustic performance of dissipative silencer was evaluated to determine the effectiveness of perforated duct porosity and absorbent material density in reducing occupational noise exposure propagated from centrifugal fan.Design charts were applied to predict noise reduction and length of a dissipative silencer.Dissipative silencers with various punched duct porosity(14%,30%and 40%)and sound absorbent density(80 Kg/m^(3),120 Kg/m^(3),and 140 Kg/m^(3))were designed and fabricated.According to ISO9612 and ISO11820,noise level was measured before and after installing all nine test silencers at fixed workstations around the discharge side of a centrifugal fan in a manufacturing plant.On average,the noise level at the discharge side of a fan without silencer was measured to be 93.6 dBA,whereas it was significantly mitigated by 67.4 dBA to 70.1 dBA after installing all silencers.Dynamic insertion loss for a dissipative silencer with 100 cm length was predicted to be 27.9 dB,which was in agreement with experimental ones.Although,there was no significant differences between insertion loss of silencers,the one with 30%porosity and 120 Kg/m^(3)rock wool density had the highest insertion loss of 26.2 dBA.Dissipative silencers noticeably reduced centrifugal fan noise exposures.Increasing sound absorbent density and duct porosity up to a certain limit could probably be effective in noise reduction of dissipative silencers.展开更多
RNA silencing(RNAi)is a nucleotide sequence-specific process that results in blockage of gene expression(Baulcombe,2004,2005;Gunter Meister,2004;Vaucheret,2006;Chinnusamy and Zhu,2009;Heo and Kim,2009;Matzke et al.,20...RNA silencing(RNAi)is a nucleotide sequence-specific process that results in blockage of gene expression(Baulcombe,2004,2005;Gunter Meister,2004;Vaucheret,2006;Chinnusamy and Zhu,2009;Heo and Kim,2009;Matzke et al.,2009;Simon and Meyers,2011).In plants,post-transcriptional gene silencing(PTGS)occurs in the cytoplasm that is induced by small RNAs(sRNAs),which are the products of double-stranded RNAs(dsRNAs)processed by Dicer-like ribonucleases and achieve specificity through base pairing with targeted RNA sequences(Carmell and Hannon,2004;Gunter Meister,2004;Gasciolli et al.,2005).In an alternative pathway occurring in the nucleus,sRNAs corresponding to promoter sequences direct the silencing machinery to block the transcription of homologous promoters(transcriptional gene silencing,TGS).This process requires 24-nt sRNAs for de novo DNA methylation,a process known as RNA-directed DNA methylation(RdDM)(James P.Jackson and Jacobsen,2002;Matzke and Birchler,2005;Matzke et al.,2007;Zilberman et al.,2007;Wierzbicki et al.,200&Zilberman,2008).Histone modifications also play an important role in the establishment and maintenance of DNA methylation(Zuzana Jasencakova,2003;Ooi et al.,2007;Cedar and Bergman,2009;Law and Jacobsen,2010).In plants,it has been shown that the transcription of exogenous transgene transcribing inverted-repeat(exo-/R)sequences produces dsRNAs,triggering exo-//?PTGS that is negatively autoregulated through methylation spreading/transitive silencing.This transitive silencing「einforces the self-silencing of exo-//?and leads to reduced exo-//?PTGS and exo-/R-derived sRNA production.exo-/R-derived sRNAs function as mobile signals to trigger sRNA-mediated non-cell autonomous silencing of an endogenous homologous target gene(endo-gene)(Dong et al.,2011).It remains unknown whether histone modifications play a role in the exo-IR-triggered endo-gene silencing.展开更多
Optimal plant height is crucial in modern agriculture, influencing lodging resistance and facilitating mechanized crop production. Upland cotton (Gossypium hirsutum) is the most important fiber crop globally;however, ...Optimal plant height is crucial in modern agriculture, influencing lodging resistance and facilitating mechanized crop production. Upland cotton (Gossypium hirsutum) is the most important fiber crop globally;however, the genetic basis underlying plant height remains largely unexplored. In this study, we conducted a genome-wide association study to identify a major locus controlling plant height (PH1) in upland cotton. This locus encodes gibberellin 2-oxidase 1A (GhPH1) and features a 1133-bp structural variation (PAVPH1) located approximately 16 kb upstream. The presence or absence of PAVPH1 influences the expression of GhPH1, thereby affecting plant height. Further analysis revealed that a gibberellin-regulating transcription factor (GhGARF) recognizes and binds to a specific CATTTG motif in both the GhPH1 promoter and PAVPH1. This interaction downregulates GhPH1, indicating that PAVPH1 functions as a distant upstream silencer. Intriguingly, we found that DWARF53 (D53), a key repressor of the strigolactone (SL) signaling pathway, directly interacts with GhGARF to inhibit its binding to targets. Moreover, we identified a previously unrecognized gibberellin-SL crosstalk mechanism mediated by the GhD53-GhGARF-GhPH1/PAVPH1 module, which is crucial for regulating plant height in upland cotton. These findings shed light on the genetic basis and gene interaction network underlying plant height, providing valuable insights for the development of semi-dwarf cotton varieties through precise modulation of GhPH1 expression.展开更多
The NAC(NAM,ATAF1/2,and CUC2)is a defense-associated transcription factor(TF)family that positively regulates defense responses to pathogen infection.TaNAC069 positively regulates resistance in wheat to Puccinia triti...The NAC(NAM,ATAF1/2,and CUC2)is a defense-associated transcription factor(TF)family that positively regulates defense responses to pathogen infection.TaNAC069 positively regulates resistance in wheat to Puccinia triticina(Pt).However,the molecular mechanism of its interaction with a Pt effector is not clear.We found that Pt effector Pt-1234 interacts with TaNAC069 to subvert host immunity during Pt infection.Quantitative real-time PCR analysis showed that expression of Pt-1234 was significantly upregulated during the early stage of Pt infection.Protein-mediated cell death assays in wheat showed that the Pt-1234 protein was unable to induce cell death in wheat near-isogenic lines carrying different leaf rust resistance genes,whereas it suppressed BAX-induced cell death in leaves of Nicotiana benthamiana.Silencing of Pt-1234 by host-induced gene silencing(HIGS)significantly reduced the virulence of Pt in the susceptible wheat variety Thatcher.The C subdomain of TaNAC069 was responsible for its interaction with Pt-1234,and the E subdomain was required for TaNAC069-mediated defense responses to Pt in planta.These findings indicate that Pt utilizes Pt-1234 to interact with wheat transcription factor TaNAC069 through its C subdomain,thereby modulating wheat immunity.展开更多
Traumatic brain injury and Alzheimer's disease share pathological similarities,including neuronal loss,amyloid-βdeposition,tau hyperphosphorylation,blood-brain barrier dysfunction,neuroinflammation,and cognitive ...Traumatic brain injury and Alzheimer's disease share pathological similarities,including neuronal loss,amyloid-βdeposition,tau hyperphosphorylation,blood-brain barrier dysfunction,neuroinflammation,and cognitive deficits.Furthermore,traumatic brain injury can exacerbate Alzheimer's disease-like pathologies,potentially leading to the development of Alzheimer's disease.Nanocarriers offer a potential solution by facilitating the delive ry of small interfering RNAs across the blood-brain barrier for the targeted silencing of key pathological genes implicated in traumatic brain injury and Alzheimer's disease.U nlike traditional approaches to neuro regeneration,this is a molecula r-targeted strategy,thus avoiding non-specific drug actions.This review focuses on the use of nanocarrier systems for the efficient and precise delive ry of siRNAs,discussing the advantages,challenges,and future directions.In principle,siRNAs have the potential to target all genes and non-targetable protein s,holding significant promise for treating various diseases.Among the various therapeutic approaches currently available for neurological diseases,siRNA gene silencing can precisely"turn off"the expression of any gene at the genetic level,thus radically inhibiting disease progression;however,a significant challenge lies in delivering siRNAs across the blood-brain barrier.Nanoparticles have received increasing attention as an innovative drug delive ry tool fo r the treatment of brain diseases.They are considered a potential therapeutic strategy with the advantages of being able to cross the blood-brain barrier,targeted drug delivery,enhanced drug stability,and multifunctional therapy.The use of nanoparticles to deliver specific modified siRNAs to the injured brain is gradually being recognized as a feasible and effective approach.Although this strategy is still in the preclinical exploration stage,it is expected to achieve clinical translation in the future,creating a new field of molecular targeted therapy and precision medicine for the treatment of Alzheimer's disease associated with traumatic brain injury.展开更多
Dear Editor,I am writing in response to the article“Assessment of nurses’workplace silence behavior motives:A cross-sectional study”by Alhojairi et al.published in the September 2024 issue of the International Jour...Dear Editor,I am writing in response to the article“Assessment of nurses’workplace silence behavior motives:A cross-sectional study”by Alhojairi et al.published in the September 2024 issue of the International Journal of Nursing Sciences[1].This is a letter written by a nurse with 10 years of clinical work experience and a personal interest in team dynamics.I appreciate the authors'recommendations on mitigating workplace silence among nurses to enhance clinical work development,and I believe their proposals could be expanded further.展开更多
The idea of the earthquake (EQ) focus as a coherent electromagnetic (EM) emitter is suggested. This idea elucidates enigmatic properties of the EM voice of the focus: its emission is not continuous, occurring periodic...The idea of the earthquake (EQ) focus as a coherent electromagnetic (EM) emitter is suggested. This idea elucidates enigmatic properties of the EM voice of the focus: its emission is not continuous, occurring periodically in flashes, which are structured as the pulses occurring in bursts;the EM activity increases starting approximately two weeks before the EQ and becomes very weak or completely disappears one day before the EQ (gap of silence). The mechanism of coherency starts with electric discharges of any mini-cracks as a mini-capacitor, which generates EM waves;the latter induces discharges of other cracks, multiplying the amplitude of the wave and creating the pulse of seismic EM signal. It is an avalanche-like mechanism of coherency, which transforms even weak EM signals into intensive EM seismic flashes.展开更多
In the context of Michel Serres'and posthumanism's proposal of rethinking the human and the world in a perspective of universal co-belonging,silence(of the human word)assumes the function of a catalyst for the...In the context of Michel Serres'and posthumanism's proposal of rethinking the human and the world in a perspective of universal co-belonging,silence(of the human word)assumes the function of a catalyst for the recognition of the human body in its aesthetic,cognitive,relational,and hybrid dimensionality,and of the world in its agency(including artistic).Within this framework,the contribution proposes a reading of art as a relation and catalyzer of relations,that is,as a(re)activation of positive relations of the human with a world that reveals itself to be increasingly hyper-complex.Taking Serresian ideas on artistic practices as not(only)human forms of expression and some posthumanist"isomorphic"positions on non-human agency as tools,the research then highlights the more-than-human scope of art.展开更多
Researchers commonly use cyclization recombination enzyme/locus of X-over P1(Cre/loxP)technology-based conditional gene knockouts of model mice to investigate the functional roles of genes of interest in Sertoli and L...Researchers commonly use cyclization recombination enzyme/locus of X-over P1(Cre/loxP)technology-based conditional gene knockouts of model mice to investigate the functional roles of genes of interest in Sertoli and Leydig cells within the testis.However,the shortcomings of these genetic tools include high costs,lengthy experimental periods,and limited accessibility for researchers.Therefore,exploring alternative gene silencing techniques is of great practical value.In this study,we employed adeno-associated virus(AAV)as a vector for gene silencing in Sertoli and Leydig cells.Our findings demonstrated that AAV serotypes 1,8,and 9 exhibited high infection efficiency in both types of testis cells.Importantly,we discovered that all three AAV serotypes exhibited exquisite specificity in targeting Sertoli cells via tubular injection while demonstrating remarkable selectivity in targeting Leydig cells via interstitial injection.We achieved cell-specific knockouts of the steroidogenic acute regulatory(Star)and luteinizing hormone/human chorionic gonadotropin receptor(Lhcgr)genes in Leydig cells,but not in Sertoli cells,using AAV9-single guide RNA(sgRNA)-mediated gene editing in Rosa26-LSL-Cas9mice.Knockdown of androgen receptor(Ar)gene expression in Sertoli cells of wild-type mice was achieved via tubular injection of AAV9-short hairpinRNA(shRNA)-mediated targeting.Our findings offer technical approaches for investigating gene function in Sertoli and Leydig cells through AAV9-mediated gene silencing.展开更多
Gliomas are the most common intracranial tumors with poor survival and high mortality.Furthermore,the clinical efficacy of current drugs is still not ideal;despite the development of several therapeutic drugs over the...Gliomas are the most common intracranial tumors with poor survival and high mortality.Furthermore,the clinical efficacy of current drugs is still not ideal;despite the development of several therapeutic drugs over the past decades and tumor progression or recurrence is inevitable in many patients.RNAibased therapy presents a novel disease-related gene targeting therapy,including otherwise undruggable genes,and generates therapeutic options.However,the therapeutic effect of siRNA is hindered by multiple biological barriers,primarily the blood-brain barrier(BBB).A glycoprotein-derived peptide-mediated delivery system is the preferred option to resolve this phenomenon.RDP,a polypeptide composed of 15 amino acids derived from rabies virus glycoprotein(RVG),possesses an N-type acetylcholine receptor(nAChR)-binding efficiency similar to that of RVG29.Given its lower cost and small particle size when used as a ligand,RDP should be extensively evaluated.First,we verified the brain-targeting efficacyy of RDP at the cellular and animal levels and further explored the possibility of using the RDP-oligoarginine peptide(designated RDP-5R)as a bio-safe vehicle to deliver therapeutic siRNA into glioma cells in vitro and in vivo.The polypeptide carrier possesses a diblock design composed of oligoarginine for binding siRNA through electrostatic interactions and RDP for cascade BBB-and glioma cell-targeting.The results indicated that RDP-R5/siRNA nanoparticles exhibited stable and suitable physicochemical properties for in vivo application,desirable glioma-targeting effects,and therapeutic efficiency.As a novel and efficient polypeptide carrier,RDP-based polypeptides hold great promise as a noninvasive,safe,and efficient treatment for various brain diseases.展开更多
The occurrence,development,and metastasis of tumors often entail abnormal expression of genetic substances.Monitoring and regulating changes in intracellular nucleic acid substances hold promise for achieving accurate...The occurrence,development,and metastasis of tumors often entail abnormal expression of genetic substances.Monitoring and regulating changes in intracellular nucleic acid substances hold promise for achieving accurate tumor diagnosis and effective treatment.However,the effectiveness of integrated tumor diagnosis and treatment based on functional nucleic acids still needs to be improved.In this study,we engineered a multifunctional nucleic acid delivery system grounded in a cationic covalent organic framework carrier.This system not only showcases effective gene silencing but also boasts high sensitivity in detecting miR21 levels within tumor cells,enabling real-time monitoring of tumor gene therapy efficacy.The construction of this integrated functional nucleic acid delivery platform provides new ideas for precise tumor detection and effective tumor treatment.展开更多
文摘The optimization of the acoustic silencer volume is very important to develop it and to get high-performance,the importance of the silencer was appeared in industrial field to eliminate the noise of the duct by efficient and economical method.The main goal of this research is to optimize the transmission loss(TL)by analytical method of the Double-Chamber Silencer(DCS),the TL has been selected as the main parameter in silencer because it does not based on the source or the termination impedances.First we calculated the power transmission coefficient(PTC)and the TL of an acoustic silencer,then used the Lagrange method to optimize the silencer length.All calculation of silencer data is obtained by solving the governing equations in commercial software Matlab®.A several calculations for different silencer length at many frequency ranges were performed simultaneously.Finally,this research supports the efficient and rapid techniques for DCS optimal design under narrow space.The results show that the acoustic TL is maximized at the desired frequency.
基金Project(NRF-2010-013-D00007) supported by the National Research Foundation of KoreaProject supported by 2010 Year Research Professor Fund of Gyeongsang National University, Korea and NIIED Korea
文摘The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage of structures, creating an environmental, social problem and also military problems such as exposure of location of troops. This high pressure impulsive sound, generated during the blast flow, was studied and attenuated. An axisymmetric computational domain was constructed by employing Spalart Allmaras turbulence model. Approximately 90% of pressure and 20 dB of sound level are reduced due to the use of the three baffle silencer at the muzzle end of the gun barrel, in comparison with the tank gun without silencer. Also, the sound pressure level at different points in the ambient region shows the same attenuation in results. This study will be helpful to understand the blast wave characteristics and also to get a good idea to design silencer for large caliber weapon system.
基金Project(11174065)supported by the National Natural Science Foundation of China
文摘The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies.
文摘The developmental stage-specific silencing of the human ε-globin gene during embryonic life is controlled, inpart, by the silencer (-392bp～-177bp) upstream of thisgene. In order to elucidate its role, the nuclear extractfrom the human fetal liver has been prepared and the interactions between trans-acting factors and this silencerelement have been examined. By using DNasel footprinting assay, a major protected region from -278bp to -235bpwithin this silencer element was identified. Furthermore,we found in gel mobility shift assay and Southwestern blotting assay that there were at least four trans-acting factors (MW ≈ 32, 28, 26 and 22kD) in the nuclear extractisolated from the human fetal liver, which could specifically bind to this region. Our results suggested that thesetrans-acting factors might play an important role in silencing the human embryonic ε-globin gene expression at thefetal stage through the interactions with this silencer.
基金the National Natural Science Foundation of China under Grant No.10474016.
文摘In marine engine exhaust silencing systems, the presence of exhaust gas flow influences the sound propagation inside the systems and the acoustic attenuation performance of silencers. In order to investigate the effects of three-dimensional gas flow and acoustic damping on the acoustic attenuation characteristics of marine engine exhaust silencers, a dual reciprocity boundary element method (DRBEM) was developed. The acoustic governing equation in three-dimensional potential flow was derived first, and then the DRBEM numerical procedure is given. Compared to the conventional boundary element method (CBEM), the DRBEM considers the second order terms of flow Mach number in the acoustic governing equation, so it is suitable for the cases with higher Mach number subsonic flow. For complex exhaust silencers, it is difficult to apply the single-domain boundary element method, so a substructure approach based on the dual reciprocity boundary element method is presented. The experiments for measuring transmission loss of silencers are conducted, and the experimental setup and measurements are explained. The transmission loss of a single expansion chamber silencer with extended inlet and outlet were predicted by DRBEM and compared with the measurements. The good agreements between predictions and measurements are observed, which demonstrated that the derived acoustic governing equation and the DRBEM numerical procedure in the present study are correct.
文摘Timbre,as one of the essential elements of sound,plays an important role in determining sound properties,whereas its manipulation has been remaining challenging for passive mechanical systems due to the intrinsic dispersion nature of resonances.Here,we present a meta-silencer supporting intensive mode density as well as highly tunable intrinsic loss and offering a fresh pathway for designable timbre in broadband.Strong global coupling is induced by intensive mode density and delicately modulated with the guidance of the theoretical model,which efficiently suppresses the resonance dispersion and provides desirable frequency-selective wave-manipulation capacity for timbre tuning.As proof-of-concept demonstrations for our design concepts,we propose three meta-silencers with the designing targets of high-efficiency broadband sound attenuation,efficiency-controlled sound attenuation and designable timbre,respectively.The proposed meta-silencers all operate in a broadband frequency range from 500 to 3200 Hz and feature deep-subwavelength sizes around 50 mm.Our work opens up a fundamental avenue to manipulate the timbre with passive resonances-controlled acoustic metamaterials and may inspire the development of novel multifunctional devices in noise-control engineering,impedance engineering,and architectural acoustics.
基金the framework of a faculty research project under the code of Ethics Committee of IR.QUMS.REC.1396.163.We also thank Mehrdad Keshavarz Siahposh and Mohammad Soleiman Abady for their technical assistance in all our experimental work.
文摘Acoustic performance of dissipative silencer was evaluated to determine the effectiveness of perforated duct porosity and absorbent material density in reducing occupational noise exposure propagated from centrifugal fan.Design charts were applied to predict noise reduction and length of a dissipative silencer.Dissipative silencers with various punched duct porosity(14%,30%and 40%)and sound absorbent density(80 Kg/m^(3),120 Kg/m^(3),and 140 Kg/m^(3))were designed and fabricated.According to ISO9612 and ISO11820,noise level was measured before and after installing all nine test silencers at fixed workstations around the discharge side of a centrifugal fan in a manufacturing plant.On average,the noise level at the discharge side of a fan without silencer was measured to be 93.6 dBA,whereas it was significantly mitigated by 67.4 dBA to 70.1 dBA after installing all silencers.Dynamic insertion loss for a dissipative silencer with 100 cm length was predicted to be 27.9 dB,which was in agreement with experimental ones.Although,there was no significant differences between insertion loss of silencers,the one with 30%porosity and 120 Kg/m^(3)rock wool density had the highest insertion loss of 26.2 dBA.Dissipative silencers noticeably reduced centrifugal fan noise exposures.Increasing sound absorbent density and duct porosity up to a certain limit could probably be effective in noise reduction of dissipative silencers.
基金financially supported by the National Natural Science Foundation of China (31730078 to H.S.G., and 31600124 to J.H.Z.)
文摘RNA silencing(RNAi)is a nucleotide sequence-specific process that results in blockage of gene expression(Baulcombe,2004,2005;Gunter Meister,2004;Vaucheret,2006;Chinnusamy and Zhu,2009;Heo and Kim,2009;Matzke et al.,2009;Simon and Meyers,2011).In plants,post-transcriptional gene silencing(PTGS)occurs in the cytoplasm that is induced by small RNAs(sRNAs),which are the products of double-stranded RNAs(dsRNAs)processed by Dicer-like ribonucleases and achieve specificity through base pairing with targeted RNA sequences(Carmell and Hannon,2004;Gunter Meister,2004;Gasciolli et al.,2005).In an alternative pathway occurring in the nucleus,sRNAs corresponding to promoter sequences direct the silencing machinery to block the transcription of homologous promoters(transcriptional gene silencing,TGS).This process requires 24-nt sRNAs for de novo DNA methylation,a process known as RNA-directed DNA methylation(RdDM)(James P.Jackson and Jacobsen,2002;Matzke and Birchler,2005;Matzke et al.,2007;Zilberman et al.,2007;Wierzbicki et al.,200&Zilberman,2008).Histone modifications also play an important role in the establishment and maintenance of DNA methylation(Zuzana Jasencakova,2003;Ooi et al.,2007;Cedar and Bergman,2009;Law and Jacobsen,2010).In plants,it has been shown that the transcription of exogenous transgene transcribing inverted-repeat(exo-/R)sequences produces dsRNAs,triggering exo-//?PTGS that is negatively autoregulated through methylation spreading/transitive silencing.This transitive silencing「einforces the self-silencing of exo-//?and leads to reduced exo-//?PTGS and exo-/R-derived sRNA production.exo-/R-derived sRNAs function as mobile signals to trigger sRNA-mediated non-cell autonomous silencing of an endogenous homologous target gene(endo-gene)(Dong et al.,2011).It remains unknown whether histone modifications play a role in the exo-IR-triggered endo-gene silencing.
基金funded by The National Key Research and Development Program of China(grant nos.2021YFF1000101 to S.H.and 2022YFD1200300 to X.D.)the National Natural Science Foundation of China(grant no.32122062 to S.H.)the Agricultural Science,Technology Innovation Program of the Chinese Academy of Agricultural Sciences and Henan Provincial Department of Science and Technology research project(grant no.232102111076).
文摘Optimal plant height is crucial in modern agriculture, influencing lodging resistance and facilitating mechanized crop production. Upland cotton (Gossypium hirsutum) is the most important fiber crop globally;however, the genetic basis underlying plant height remains largely unexplored. In this study, we conducted a genome-wide association study to identify a major locus controlling plant height (PH1) in upland cotton. This locus encodes gibberellin 2-oxidase 1A (GhPH1) and features a 1133-bp structural variation (PAVPH1) located approximately 16 kb upstream. The presence or absence of PAVPH1 influences the expression of GhPH1, thereby affecting plant height. Further analysis revealed that a gibberellin-regulating transcription factor (GhGARF) recognizes and binds to a specific CATTTG motif in both the GhPH1 promoter and PAVPH1. This interaction downregulates GhPH1, indicating that PAVPH1 functions as a distant upstream silencer. Intriguingly, we found that DWARF53 (D53), a key repressor of the strigolactone (SL) signaling pathway, directly interacts with GhGARF to inhibit its binding to targets. Moreover, we identified a previously unrecognized gibberellin-SL crosstalk mechanism mediated by the GhD53-GhGARF-GhPH1/PAVPH1 module, which is crucial for regulating plant height in upland cotton. These findings shed light on the genetic basis and gene interaction network underlying plant height, providing valuable insights for the development of semi-dwarf cotton varieties through precise modulation of GhPH1 expression.
基金funded by State Key Laboratory of North China Crop Improvement and Regulation(NCCIR2023ZZ-10)the National Natural Science Foundation of China(32172384 and 31501623)+1 种基金the Natural Science Foundation of Hebei(C2020204028)the Science and Technology Research Project of Higher Education of Hebei(ZC2023178).
文摘The NAC(NAM,ATAF1/2,and CUC2)is a defense-associated transcription factor(TF)family that positively regulates defense responses to pathogen infection.TaNAC069 positively regulates resistance in wheat to Puccinia triticina(Pt).However,the molecular mechanism of its interaction with a Pt effector is not clear.We found that Pt effector Pt-1234 interacts with TaNAC069 to subvert host immunity during Pt infection.Quantitative real-time PCR analysis showed that expression of Pt-1234 was significantly upregulated during the early stage of Pt infection.Protein-mediated cell death assays in wheat showed that the Pt-1234 protein was unable to induce cell death in wheat near-isogenic lines carrying different leaf rust resistance genes,whereas it suppressed BAX-induced cell death in leaves of Nicotiana benthamiana.Silencing of Pt-1234 by host-induced gene silencing(HIGS)significantly reduced the virulence of Pt in the susceptible wheat variety Thatcher.The C subdomain of TaNAC069 was responsible for its interaction with Pt-1234,and the E subdomain was required for TaNAC069-mediated defense responses to Pt in planta.These findings indicate that Pt utilizes Pt-1234 to interact with wheat transcription factor TaNAC069 through its C subdomain,thereby modulating wheat immunity.
基金supported by Open Project of the Key Laboratory of Trauma and Orthopedics Research Medicine in Henan Province,No.HZKFKT20220504(to YZ)the National Natural Science Foundation of China,No.32000877(to YZ)and Open Scientific Research Program of Military Logistics,No.BLB20J009(to YZ)。
文摘Traumatic brain injury and Alzheimer's disease share pathological similarities,including neuronal loss,amyloid-βdeposition,tau hyperphosphorylation,blood-brain barrier dysfunction,neuroinflammation,and cognitive deficits.Furthermore,traumatic brain injury can exacerbate Alzheimer's disease-like pathologies,potentially leading to the development of Alzheimer's disease.Nanocarriers offer a potential solution by facilitating the delive ry of small interfering RNAs across the blood-brain barrier for the targeted silencing of key pathological genes implicated in traumatic brain injury and Alzheimer's disease.U nlike traditional approaches to neuro regeneration,this is a molecula r-targeted strategy,thus avoiding non-specific drug actions.This review focuses on the use of nanocarrier systems for the efficient and precise delive ry of siRNAs,discussing the advantages,challenges,and future directions.In principle,siRNAs have the potential to target all genes and non-targetable protein s,holding significant promise for treating various diseases.Among the various therapeutic approaches currently available for neurological diseases,siRNA gene silencing can precisely"turn off"the expression of any gene at the genetic level,thus radically inhibiting disease progression;however,a significant challenge lies in delivering siRNAs across the blood-brain barrier.Nanoparticles have received increasing attention as an innovative drug delive ry tool fo r the treatment of brain diseases.They are considered a potential therapeutic strategy with the advantages of being able to cross the blood-brain barrier,targeted drug delivery,enhanced drug stability,and multifunctional therapy.The use of nanoparticles to deliver specific modified siRNAs to the injured brain is gradually being recognized as a feasible and effective approach.Although this strategy is still in the preclinical exploration stage,it is expected to achieve clinical translation in the future,creating a new field of molecular targeted therapy and precision medicine for the treatment of Alzheimer's disease associated with traumatic brain injury.
文摘Dear Editor,I am writing in response to the article“Assessment of nurses’workplace silence behavior motives:A cross-sectional study”by Alhojairi et al.published in the September 2024 issue of the International Journal of Nursing Sciences[1].This is a letter written by a nurse with 10 years of clinical work experience and a personal interest in team dynamics.I appreciate the authors'recommendations on mitigating workplace silence among nurses to enhance clinical work development,and I believe their proposals could be expanded further.
文摘The idea of the earthquake (EQ) focus as a coherent electromagnetic (EM) emitter is suggested. This idea elucidates enigmatic properties of the EM voice of the focus: its emission is not continuous, occurring periodically in flashes, which are structured as the pulses occurring in bursts;the EM activity increases starting approximately two weeks before the EQ and becomes very weak or completely disappears one day before the EQ (gap of silence). The mechanism of coherency starts with electric discharges of any mini-cracks as a mini-capacitor, which generates EM waves;the latter induces discharges of other cracks, multiplying the amplitude of the wave and creating the pulse of seismic EM signal. It is an avalanche-like mechanism of coherency, which transforms even weak EM signals into intensive EM seismic flashes.
文摘In the context of Michel Serres'and posthumanism's proposal of rethinking the human and the world in a perspective of universal co-belonging,silence(of the human word)assumes the function of a catalyst for the recognition of the human body in its aesthetic,cognitive,relational,and hybrid dimensionality,and of the world in its agency(including artistic).Within this framework,the contribution proposes a reading of art as a relation and catalyzer of relations,that is,as a(re)activation of positive relations of the human with a world that reveals itself to be increasingly hyper-complex.Taking Serresian ideas on artistic practices as not(only)human forms of expression and some posthumanist"isomorphic"positions on non-human agency as tools,the research then highlights the more-than-human scope of art.
基金supported by the National Natural Science Foundation of China(No.82070872 and No.82370854 to JXL)Innovative and Entrepreneurial Team of Jiangsu Province(No.JSSCTD2021 to JXL)+1 种基金China Postdoctoral Science Foundation(2023M741790 to JP)Jiangsu Funding Program for Excellent Postdoctoral Talent(2023ZB558 to JP).
文摘Researchers commonly use cyclization recombination enzyme/locus of X-over P1(Cre/loxP)technology-based conditional gene knockouts of model mice to investigate the functional roles of genes of interest in Sertoli and Leydig cells within the testis.However,the shortcomings of these genetic tools include high costs,lengthy experimental periods,and limited accessibility for researchers.Therefore,exploring alternative gene silencing techniques is of great practical value.In this study,we employed adeno-associated virus(AAV)as a vector for gene silencing in Sertoli and Leydig cells.Our findings demonstrated that AAV serotypes 1,8,and 9 exhibited high infection efficiency in both types of testis cells.Importantly,we discovered that all three AAV serotypes exhibited exquisite specificity in targeting Sertoli cells via tubular injection while demonstrating remarkable selectivity in targeting Leydig cells via interstitial injection.We achieved cell-specific knockouts of the steroidogenic acute regulatory(Star)and luteinizing hormone/human chorionic gonadotropin receptor(Lhcgr)genes in Leydig cells,but not in Sertoli cells,using AAV9-single guide RNA(sgRNA)-mediated gene editing in Rosa26-LSL-Cas9mice.Knockdown of androgen receptor(Ar)gene expression in Sertoli cells of wild-type mice was achieved via tubular injection of AAV9-short hairpinRNA(shRNA)-mediated targeting.Our findings offer technical approaches for investigating gene function in Sertoli and Leydig cells through AAV9-mediated gene silencing.
基金supported by CAMS Innovation Fund for Medical Sciences(No.2021-I2M-1-026,China).
文摘Gliomas are the most common intracranial tumors with poor survival and high mortality.Furthermore,the clinical efficacy of current drugs is still not ideal;despite the development of several therapeutic drugs over the past decades and tumor progression or recurrence is inevitable in many patients.RNAibased therapy presents a novel disease-related gene targeting therapy,including otherwise undruggable genes,and generates therapeutic options.However,the therapeutic effect of siRNA is hindered by multiple biological barriers,primarily the blood-brain barrier(BBB).A glycoprotein-derived peptide-mediated delivery system is the preferred option to resolve this phenomenon.RDP,a polypeptide composed of 15 amino acids derived from rabies virus glycoprotein(RVG),possesses an N-type acetylcholine receptor(nAChR)-binding efficiency similar to that of RVG29.Given its lower cost and small particle size when used as a ligand,RDP should be extensively evaluated.First,we verified the brain-targeting efficacyy of RDP at the cellular and animal levels and further explored the possibility of using the RDP-oligoarginine peptide(designated RDP-5R)as a bio-safe vehicle to deliver therapeutic siRNA into glioma cells in vitro and in vivo.The polypeptide carrier possesses a diblock design composed of oligoarginine for binding siRNA through electrostatic interactions and RDP for cascade BBB-and glioma cell-targeting.The results indicated that RDP-R5/siRNA nanoparticles exhibited stable and suitable physicochemical properties for in vivo application,desirable glioma-targeting effects,and therapeutic efficiency.As a novel and efficient polypeptide carrier,RDP-based polypeptides hold great promise as a noninvasive,safe,and efficient treatment for various brain diseases.
基金the National Key Research and Development Program of China(No.2021YFB3800900)National Natural Science Foundation of China(No.51925305)the talent cultivation project Funds for the Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(No.HRTP[2022]52)。
文摘The occurrence,development,and metastasis of tumors often entail abnormal expression of genetic substances.Monitoring and regulating changes in intracellular nucleic acid substances hold promise for achieving accurate tumor diagnosis and effective treatment.However,the effectiveness of integrated tumor diagnosis and treatment based on functional nucleic acids still needs to be improved.In this study,we engineered a multifunctional nucleic acid delivery system grounded in a cationic covalent organic framework carrier.This system not only showcases effective gene silencing but also boasts high sensitivity in detecting miR21 levels within tumor cells,enabling real-time monitoring of tumor gene therapy efficacy.The construction of this integrated functional nucleic acid delivery platform provides new ideas for precise tumor detection and effective tumor treatment.
