bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of a dipole-bound excited state in 4-ethynylphenoxide and comparison with the quadrupole-bound excited state in the isoelectronic 4-cyanophenoxide
Authors: Zhang Yue-Rou , Yuan Dao-Fu , Qian Chen-Hui , Wang Lai-Sheng
Published: September 2021

Negative ions do not possess Rydberg states but can have Rydberg-like nonvalence excited states near the electron detachment threshold, including dipole-bound states (DBSs) and quadrupole-bound states (QBSs). While DBSs have been studied extensively, quadrupole-bound excited states have been more rarely observed. 4-cyanophenoxide (4CP−) was the first anion observed to possess a quadrupole-bound exited state 20 cm−1 below its detachment threshold. Here, we report the observation of a DBS in the isoelectronic 4-ethynylphenoxide anion (4EP−), providing a rare opportunity to compare the behaviors of a dipole-bound and a quadrupole-bound excited state in a pair of very similar anions. Photodetachment spectroscopy (PDS) of cryogenically cooled 4EP− reveals a DBS 76 cm−1 below its detachment threshold. Photoelectron spectroscopy (PES) at 266 nm shows that the electronic structure of 4EP− and 4CP− is nearly identical. The observed vibrational features in both the PDS and PES, as well as autodetachment from the nonvalence excited states, are also found to be similar for both anions. However, resonant two-photon detachment (R2PD) from the bound vibrational ground state is observed to be very different for the DBS in 4EP− and the QBS in 4CP−. The R2PD spectra reveal that decays take place from both the DBS and QBS to the respective anion ground electronic states within the 5 ns detachment laser pulse due to internal conversion followed by intramolecular vibrational redistribution and relaxation, but the decay mechanisms appear to be very different. In the R2PD spectrum of 4EP−, we observe strong threshold electron signals, which are due to detachment, by the second photon, of highly rotationally excited anions resulted from the decay of the DBS. On the other hand, in the R2PD spectrum of 4CP−, we observe well-resolved vibrational peaks due to the three lowest-frequency vibrational modes of 4CP−, which are populated from the decay of the QBS. The different behaviors of the R2PD spectra suggest unexpected differences between the relaxation mechanisms of the dipole-bound and quadrupole-bound excited states.
Rapid age estimation of longnose skate (
Authors: Arrington Morgan B. , Helser Thomas E. , Benson Irina M. , Essington Timothy E. , Matta Mary Elizabeth , Punt André E.
Published: September 2021

There is a paucity of age data for chondrichthyan fishes owing, in large part, to limitations in traditional age estimation methods. Fourier transform near-infrared (FT-NIR) spectroscopy has shown promise as an alternative, more efficient method for acquiring age data from chondrichthyans. However, studies are limited to sharks in the southern hemisphere. We explored FT-NIR spectroscopy to predict age for a batoid species in the northern hemisphere. The longnose skate (Raja rhina) is one of a small number of batoids for which annual band periodicity in vertebral centra has been validated, allowing for traditional age estimation and making it an ideal candidate for this study. We fit a multivariate partial least-square predictive model between FT-NIR spectra collected from vertebral centra and traditional age estimates, and tested model predictive skill by using external validation. Using FT-NIR spectroscopy, we were able to predict age for longnose skates between the ages of 1 and 14 years with precision and bias near equal to those of traditional methods in less than a quarter of the time. These results support potential for FT-NIR spectroscopy to increase the amount of age data available for assessments used to inform the conservation and management of this sensitive group of species.
Understanding the research capacity and culture of a regional allied health workforce
Authors: Crombie Angela , Borkowski Donna , Gardner Marcus , Masman Kevin , Howlett Owen
Published: September 2021

The aim of this study was to understand the research capacity and culture of a regional allied health workforce over time. A cross-sectional study design was used, with data collected using the validated Research Capacity and Culture (RCC) tool. The results were compared with an earlier administration of the RCC survey. The findings demonstrate that allied health professionals (AHPs) perceive that the organisation’s capability of conducting research is at a higher level than that of teams and individuals. Over a 4-year period the profile of the research culture of an allied health workforce in a regional health service was described similarly. The highest rated motivator for conducting research (to develop skills) and barrier to conducting research (other work roles take priority) were unchanged between 2018 and 2014. AHPs have maintained the previous viewpoint that there is research capacity at the health service and opportunities to develop the research culture. The findings of the 2018 data compared with the 2014 data highlight that specific and targeted research capacity-building strategies need to be used in order to create an active and vibrant research culture.
D-cysteine is an endogenous regulator of neural progenitor cell dynamics in the mammalian brain
Authors: Semenza Evan R. , Harraz Maged M. , Abramson Efrat , Malla Adarsha P. , Vasavda Chirag , Gadalla Moataz M. , Kornberg Michael D. , Snyder Solomon H. , Roychaudhuri Robin
Published: September 2021

Significance

d
-amino acids are increasingly recognized as important signaling molecules in the mammalian central nervous system. Cysteine is the amino acid with the fastest in vitro spontaneous racemization rate, but its
d
-stereoisomer has not been examined. Here, we establish the presence of endogenous
d
-cysteine in the mammalian brain. Using sensitive and specific assays, we delineate its actions as a negative regulator of growth factor signaling during cortical development and identify a putative binding partner mediating these effects. By describing the newest member of the
d
-amino acid family, we open an avenue of research into the functions of these multifaceted signaling molecules.
A discourse dynamics exploration of attitudinal responses towards COVID-19 in academia and media
Authors: Dong Jihua , Buckingham Louisa , Wu Hao
Published: September 2021

This study analyzes attitudinal positioning in academic and media discourse pertaining to COVID-19 from the COVID-19 Corpus and Coronavirus Corpus, using a discourse dynamics approach. Underpinning this approach is the Complex Dynamic Systems Theory (CDST), which we employ to examine the discursive practices of a discourse event across time periods (timescales). The analysis identified significant differences in attitudinal markers and noteworthy developmental patterns in attitude positioning; the developmental trajectories of attitude construction were characterized by a nonlinear developmental pattern subject to fluctuations and variability. We also discerned the existence of dynamic interaction between the uses of attitudinal markers and the reported cases of COVID-19. Methodologically, we demonstrate how the integration of the discourse dynamics approach with corpus linguistics strengthens the social contextualization of data by enabling the identification of developmental patterns of targeted language features over time, and the interconnections of these language features with contextually important social factors.
The reading habits of professional signed and spoken language interpreters
Authors: Nicodemus Brenda , Liu Minhua , McClure Sandra
Published: September 2021

Reading is a critical process for conscious learning and enhancing knowledge; however, little is known about
reading in interpreters’ professional lives. We used an online survey to collect information about the reading habits of signed
language interpreters (n = 1,382) and spoken language interpreters (n = 601) to examine overall
patterns, as well as variations, between the groups. The interpreters responded to questions regarding (a) engagement with reading
types, (b) hours spent reading, (c) motivations for reading, (d) factors that reduce engagement in reading, (e) reading in which
interpreters should engage, (f) relevance of reading to professional practice, and (g) priority of research topics for reading.
Similarities were found between the groups, with divergence in three areas – reading preparation materials, reading research
studies, and the types of research studies the participants wish to read. The results provide insights into professional
interpreters’ engagement with reading and its application to their professional practice.
Simulation and experiment investigaton of electromagnetic and thermal field during induction cladding
Authors: Yu Jing , Zhang Shuai , Liu Yanchuan , Wang Jinlong
Published: September 2021

A fully electrical–magnetic–thermal coupled model is proposed to investigate the heating mechanism of induction cladding. The simulation results reveal that the coating and the thin layer close to the substrate surface were heated layer by layer. Furthermore, the non-uniform electromagnetic field generated an uneven temperature distribution, which had a larger impact in the longitudinal direction than in the cross section. The maximum relative errors between the simulated and measured temperatures indiacate that the numerical calculation fit the experimental results well. The impact of the non-uniform temperature distribution on the coating properties was experimentally studied. The specimen in the middle position had a more complicated phase composition, lower porosity, and higher microhardness than those at the two ends.
Imagining national solidarity: Strangers-turned-friends-turned-brothers
Authors: Kaplan Danny
Published: September 2021

There is limited cultural analysis of the tropes and metaphors underlying the discourse of national solidarity. This article revisits three central approaches to bounded solidarity and connects them with distinctive tropes of personal relationships: solidarity-through-sameness encapsulated in the family metaphor; solidarity as an impersonal relationship between strangers; and solidarity as an extension of sociability encapsulated in the friendship metaphor. I examine these tropes in terms of collective perceptions of simultaneous and mythic time and a meta-narrative of salvation. The national imagination can be distinguished from civic and ethnic forms of belonging by its enactment of a dual transformation from strangers to friends and from newfound friends to rediscovered brothers of a timeless and primordial tribe. While much of the nationhood literature assumes a causal pathway from national identity to solidarity, this fraternisation of friendship points to a reverse route from trust between compatriots to feelings of loyalty to the nation.
GaN PNP light-emitting bipolar junction transistor
Authors: Fu Wai Yuen , Choi Hoi Wai
Published: September 2021

An light-emitting bipolar transistor (LEBJT) has been developed in response to aspirations for on-chip electronics with GaN-based light-emitting diode (LED) devices. The design utilizes the existing p-n junction of an LED structure to construct a PNP bipolar junction transistor comprising two back-to-back p-n junctions, saving the need for customized structures or epitaxial regrowth. Two designs of monolithic GaN LEBJTs have been demonstrated in this work—an LEBJT with a larger emitter area size for conversion of electronic to optical signal, as well as an LEBJT with reduced emitter area for boosting of current gain. Employing an emitter comprising an array of nanopillars patterned by nanosphere lithography, the LEBJT exhibits an average current gain of 20 and a bandwidth of 180 MHz.
Spectrality of a class of self-affine measures on

R2

*
Authors: Chen Ming-Liang , Liu Jing-Cheng , Wang Xiang-Yang
Published: September 2021

In this work, we study the spectral property of a class of self-affine measures μ

M,D
on

R

2

generated by an expanding real matrix

M
=
diag

ρ

1

−
1

,

ρ

2

−
1

and a non-collinear integer digit set

D
=

{

(

0
,
0

)

t

,

(

α

1

,

α

2

)

t

,

(

β

1

,

β

2

)

t

}

with

α

i

−
2

β

i

∉
3
Z

, i = 1, 2. We give the sufficient and necessary conditions so that μ

M,D
becomes a spectral measure, i.e., there exists a countable subset

Λ
⊂

R

2

such that {e
2πi⟨λ,x⟩: λ ∈ Λ} forms an orthonormal basis for L
2(μ

M,D
). This extends the results of Dai, Fu and Yan (2021 Appl. Comput. Harmon. Anal.
52 63–81) and Deng and Lau (2015 J. Funct. Anal.
269 1310–1326).
Applying Lambert problem to association of radar-measured orbit tracks of space objects
Authors: Liu Lei , Li Bin , Chen Jun-Yu , Lei Xiang-Xu , Zhao Guang-Yu , Sang Ji-Zhang
Published: September 2021

Thousands of orbit tracks of space objects are collected by a radar each day, and many may be from uncatalogued objects. As such, it is an urgent demand to catalogue the uncatalogued objects, which requires to determine whether two or more un-correlated tracks (UCTs) are from the same object. This paper proposes to apply the Lambert problem to associate two radar-measured orbit tracks of LEO and HEO objects. A novel method of position correction is proposed to correct the secular and short periodic effects caused by theJ2perturbation, making the Lambert problem applicable to perturbed orbit tracks. After that, an orbit selection method based on the characteristics of residuals solves the multiple-revolution Lambert problem. Extensive experiments with simulated radar measurements of LEO and HEO objects are carried out to assess the performance of the proposed method. It is shown that the semi-major axis can be determined with an error less than 200 m from two tracks separated by 4 days. The true positive (TP) rates for associating two LEO tracks apart by less than 6 days are 94.2%. The TP rate is still at 73.1% even for two tracks apart by 8–9 days. The results demonstrate the strong applicability of the proposed method to associate radar measurements of uncatalogued objects.
Characterization of isotope effect on ion internal transport barrier and its parameter dependence in the Large Helical Device
Authors: Kobayashi T. , Takahashi H. , Nagaoka K. , Tanaka K. , Seki R. , Yamaguchi H. , Nakata M. , Sasaki M. , Yoshinuma M. , Ida K.
Published: September 2021

In this paper, the background physics of the isotope effects in the ion internal transport barrier (ITB) are discussed in detail. An heuristic criterion for the ITB strength is defined based on the nonlinear dependence of the ion thermal diffusivity on the local ion temperature in the L-mode phase. Comparing deuterium plasmas and hydrogen plasmas, two isotope effects on the ion ITB are clarified: stronger ITBs formed in the deuterium plasmas and an ITB concomitant edge confinement degradation in the hydrogen plasmas. Principal component analysis reveals that the ion ITB becomes strong when a high input power normalized by the line averaged electron density is applied and electron density profile is peaked. A gyrokinetic simulation suggests that the ITB profile is determined by the ion temperature gradient driven turbulence, while the way the profile saturates in L-mode plasmas is unknown. In the electron density turbulence behavior, a branch transition is observed, where the increasing trend in turbulence amplitude against the ITB strength is flipped to a decreasing trend across the ITB formation. The radial electric field structure is measured by the charge exchange recombination spectroscopy system. It is found that the radial electric field shear plays a minor role in determining the ITB strength.
Designing architectural materials: from granular form to functional granular material
Authors: Dierichs Karola , Menges Achim
Published: September 2021

Designed granular materials are a novel class of architectural material system. Following one of the key paradigms of designed matter, material form and material function are closely interrelated in these systems. In this context, the article aims to contribute a parametric particle design model as an interface for this interrelation. A granular material is understood as an aggregation of large numbers of individual particles between which only short-range repulsive contact forces are acting. Granular materials are highly pertinent material systems for architecture. Due to the fact that they can act both as a solid and a liquid, they can be recycled and reconfigured multiple times and are thus highly sustainable. Designed granular materials have the added potential that the function of the granular material can be calibrated through the definition of the particles’ form. Research on the design of granular materials in architecture is nascent. In physics they have been explored mainly with respect to different particle shapes. However, no coherent parametric particle design model of designed particle shapes for granular material systems in architecture has yet been established which considers both fabrication constraints and simulation requirements. The parametric particle design model proposed in this article has been based on a design system which has been developed through feasibility tests and simulations conducted in research and teaching. Based on this design system the parametric particle design model is developed integrating both fabrication constraints for architecture-scale particle systems and the geometric requirements of established simulation methods for granular materials. Initially the design system and related feasibility tests are presented. The parametric particle design model resulting from that is then described in detail. Directions of further research are discussed especially with respect to the integration of the parametric particle design model in ‘inverse’ design methods.
Investigation of Screw Compressors for Low Pressure Ratio Applications
Authors: Lu Y , Kovacevic A , Read M , Buckney D , Endo Y
Published: September 2021

Screw compressors have been widely investigated for many applications including air and process gas compression, and refrigeration systems. There is however a surprising lack of literature for low pressure ratio application of these machines, defined here as application requiring volume ratios in the range of 1-1.5. The aim of this paper is to characterise the loss mechanisms for oil injected screw compressors with low volume index (defined as the ratio of maximum to minimum volumes during the internal compression process), V
i. This knowledge will be applied in the future to identify appropriate optimisation of rotor profiles and porting geometry for a range of low-pressure ratio applications. The current study involves the use of chamber models to investigate the influence of wrap angles and porting. This initial analysis will be developed in future work to allow a detailed parametric study of the factors that limit the performance of low V
i oil-injected screw compressors.
Reducing rotors clearance - a way to increase the performance of a screw compressor
Authors: Nitulescu M , Slujitoru C , Petrescu V , Silivestru V , Fetea G , Tomescu S
Published: September 2021

The screw compressors due to their constructive simplicity and the known advantages in operation is increasingly demanded on the market. Many companies are producing this type of compressor. The influence of leakages – conditioned by rotors clearances – on compressor performance is well known. The literature addresses the problem of coatings, but for dry compressors. Our intention is to apply this technology in the case of oil injected screw compressors (when the profile deviation is large or in the case of rotors with slight wear). Tests were performed to evaluate the performance of a screw compressor with uncoated rotors and performance of compressor assembled with coated rotors (both pairs of rotors have the same profile deviations – the profile accuracy measured is -8 ÷ -10 μm). The test aim to highlight only the influence of the coating layer – by reducing clearances – on the performance of the compressor, without performing further quality test of the coated layer. The quality of the coating process is the subject of additional research. We intend to use this technology for oil injected screw compressors both for new manufactured rotors (with large profile tolerances) and rotors with slight.
Numerical-experimental investigation of liquid slugging in the suction muffler of a hermetic reciprocating compressor
Authors: Bianchi M , Deschamps C J , Rodrigues T T , Paladino E E
Published: September 2021

Refrigerant in the liquid phase and lubricating oil that circulate in refrigeration systems may reach the compression chamber of compressors. This phenomenon of liquid slugging is detrimental to reciprocating compressors because it can damage valves and other components. A three-dimensional Eulerian multiphase model was developed using the software ANSYS CFX to predict the gas-liquid flow in a simplified suction muffler geometry. In addition, an experimental bench was designed to allow the injection of specified volumes of lubricant oil into the suction muffler and measurement of the volume that reaches the muffler outlet. The liquid slugging was observed through glass windows positioned in the test section and recorded with a high-speed camera. Measurements showed that the phenomenon of liquid slugging is random and that the volume of liquid reaching the muffler outlet increases with the oil injection pressure. The numerical model was able to predict the oil volume that reaches the muffler outlet in agreement with measurements in the case of high injection pressures, but it overpredicted the volume when the injection pressure was decreased. The visualization showed changes in the liquid phase morphology that are difficult to predict since closure models for a two-fluid model are typically developed for dispersed morphology.
Experimental analysis of reed valve movement for different reed valve designs tested in an impact fatigue test system
Authors: Tofique Muhammad Waqas , Löf Alexander , Millward Chris
Published: September 2021

Impact fatigue is a phenomenon that is the main cause of failure of reed valves in compressor systems. This phenomenon occurs in compressors due to repeated opening and closing of reed valves during suction and exhaust cycles of compressors. When the valve opens it creates bending fatigue stresses in the body of reed valve; when the valve closes it strikes against the valve plate creating impact stresses. This reed valve movement and impact is repeated billions of times. This cyclic movement influences the impact fatigue life of the reed valve and, hence, the performance of a compressor. The valve movement can be defined in terms of valve frequency, valve lift, valve velocity and impact velocity. Inside a reciprocating compressor, a number of parameters including the valve design, valve material, compressor operating frequency and suction/exhaust pressure influence the reed valve movement.

In this paper, we studied the valve movement parameters for three different suction reed valve designs manufactured from Flap-X – a martensitic stainless steel grade developed for reed valves – tested in a custom-built impact fatigue test system. The valves were excited into movement using compressed air pulses varying in frequency up to 300 Hz and varying pulse width. The valve displacement and frequency was recorded by a laser sensor at 10 000 frames per second. Before starting each test, the operating conditions such as the operating frequency and the air pulse width were pre-set in the impact fatigue test system’s control software while the applied pressure was kept constant during the test. The valve response was measured to be different for the different valve designs tested in this study. The reed valve design influenced the important reed movement parameters such as the valve lift, valve velocity, impact velocity and the frequency of valve vibrations. The valves were not tested to failure as the focus of this study was to collect the dynamic data of valve movement. However, for a practical impact fatigue testing of the reed valves intended to achieve fracture of valves, the testing should be conducted at higher frequencies to reduce test times as well as for a stable amplitude of vibration and impact velocity as shown in this study. The information obtained from this study shows the applicability of the presented impact fatigue test system to study the reed valve movement as well as their impact fatigue characteristics.
Continuous Cooling Compressor for water refrigerant heat pump
Authors: Shoyama T. , Sun H. , Kawano B. , Matsui M.
Published: September 2021

A turbo compressor was developed for water refrigerant heat pumps equipped with continuous cooling compression, in which the vapour is continuously cooled during the compression process by the latent heat of evaporation of the liquid water refrigerant sprayed into the impeller channels. One of the disadvantages of water refrigerant is that the discharge temperature during vapour compression is higher than that of fluorocarbon refrigerant. Multi-stage compression with intercooling are one of the solutions, the system becomes large. In continuous cooling compression, fine particles of water are sprayed from a nozzle embedded inside the impeller, and the water vapour in compression process is directly cooled to the saturation temperature. Therefore, if sufficient amount of spray is present, the compression process follows the saturation line in p-h diagram. Water is supplied to the spray nozzle after pressurized to 10 MPa or more using the centrifugal effect of rotor rotation. A small nozzle was developed that suppresses rotor imbalance and can withstand the load of centrifugal force. A followability index was defined as a reference for the droplets to follow the vapour flow and evaporate before colliding with the blade surface. A water-refrigerant heat pump system was constructed, and the degree of superheat of the discharged vapour was evaluated while changing the spray amount. Increasing the amount of spray decreased the superheat but COP also decreased. Saturated compression was demonstrated above a certain amount of spray, but the impeller flow was choked due to the droplet evaporation. It is desirable to assume a sufficient choke margin, or to develop a special CFD code that can take into account the droplet evaporation.
Geometric Optimisation of a Coupled Vane Compressor
Authors: Chen Q J , Ooi K T
Published: September 2021

The coupled vane compressor (CVC) is a rotary compressor with two coupled vanes which slide diametrically through the rotor during operation. As compared to most other rotary vane compressors, this CVC works well with small rotor-to-stator diameter ratio, typically less than that for all existing rotary compressors (>0.7). Hence, CVC has probably the most compact design among all rotary compressors, thus saving materials and manufacturing cost. This compressor is intended for use in room air-conditioners and refrigerators. Currently, mathematical model and measurement have been carried out to determine the working characteristics of this compressor. In this paper, a genetic algorithm with constraints handling has been devised and linked with the verified mathematical model of the CVC to search for a set of geometrical parameters which produces highest COP when working in the refrigeration cycle. During this optimisation search process, the significant design variables such as rotor radius, cylinder radius, vane thickness and valve reed thickness are allowed to vary.

In this paper, the details on the application of the optimization process, constraints handling and descriptions, objective function definitions as well as the details of optimization implementation will be presented and discussed. Results obtained will be shown and deliberated. The results show that this optimization study reconfirms the value of optimisation in compressor design.
Design optimization and test of the novel FeTu ‘compander’, utilising organic fluids within a closed cycle for HVACR applications
Authors: Subert J , Fenton J P , Hinchliffe K , Arbon I M
Published: September 2021

HVACR performance is influenced by the efficiency of the compression and expansion process. The ability to operate oil-free; with non-toxic, inert, natural working fluids such as air or CO2 holds high environmental value.

This paper presents data of the FeTu™ compander operating in a closed cycle, for means of heating and cooling. A novel system, where compression and expansion is a continuous and simultaneous process; inherently regenerating energy to assist the compression process by expanding within a positive displacement chamber. This study documents the oil-free performance with organic working fluids pertaining to HVACR applications.

Commercial 1D modelling software; GTSuite (GTS) is used to optimise cooling capacity (Q) and Coefficient of Performance (CoP). Different volume ratios (VR), pre-charge pressures, temperature inputs (ΔT) and running speeds are analysed. A multi-faceted test rig is built to compare and validate all performance data against the GTS fluid model which, once calibrated, can then be used with a high degree of certainty in predicting the performance of other applications and ΔTs. Increasing the system pre-charge pressure has a proportional impact on capacity, so this phenomenon is tested to consider the conflicting impacts of higher pressure against increased viscosity, with respect to volumetric efficiency.

The CoP of the system ranges from 1 to 5 across typical HVACR ΔTs. Low VR offers highest CoP but lowest Q, so the optimal trade-off is explored. The strengths & weaknesses are then comparatively documented against incumbent vapour cycle systems.
Comparison of Two Reverse-cycle Defrosting Methods for a R290 Split Room Air Conditioner
Authors: Du Y J , Wu J H , Wang C , Lei B W
Published: September 2021

R290 has obvious advantages in aspects of environmental protection and thermal properties, and researches on R290 room air conditioners (RACs) are attracting more and more attention. As for R290 RAC, the suction temperature is continuously low and a large number of refrigerants are dissolved in the compressor oil sump during defrosting process, resulting in a longer time length of the start-up process after defrosting. Two reverse-cycle defrosting methods, the discharge-throttling method (DTM) and suction-discharge bypass method (SDBM) are proposed in order to solve these problems. This paper compares the two defrosting methods on an R290 RAC by experiment and the results show that the defrosting time of DTM is relatively short, but the temperature at the inlet and outlet of the indoor heat exchanger is relatively low after defrosting. The SDBM can alleviate the situation of low suction temperature in the defrosting process, but the viscosity of the oil sump is large in the early stage of defrosting and the time length of the start-up process after defrosting is longer. Both methods have their own advantages and disadvantages, and the paper will provide an experimental basis for the reliability study of R290 RACs.
Part load performance of single and two stage compressors — a comparative experimental study in a R410A chiller unit
Authors: Inampudi S , Botticella F , Elbel S
Published: September 2021

The rising cooling needs for the residential and commercial air conditioning sectors and the requirement of higher SEER values increased the focus on energy efficient part load performance. Although several studies exist on the topic of capacity modulation, there is no comprehensive study that compares different modulation strategies in the same experimental facility. In a first step, this paper aims to experimentally compare two different capacity controls for scroll compressors (single speed vs two stage compressor) using the same R410A water chiller having a nominal cooling capacity of 8kW. The tests were conducted according to AHRI Standard 551/591 (2018). The Integrated Part Load Value (IPLV.SI) was used to fairly compare all the different capacity modulation strategies. Based on the experimental results, differences on the order of 8% in IPLV.SI are found.
A study into the impact of chloride ions on the make-up hydrogen compressors
Authors: Fouladivanda M , Heidary M A
Published: September 2021

The presence of unwanted chemicals in process lines and downstream equipment causes defects and failures, which sometimes have significant impacts on systems and imposes extra costs for the production process. In this study, one pair of four-stage make-up hydrogen compressors is investigated. These reciprocating compressors which serve as a part of the hydrogen treating unit have failed approximately simultaneously. The feed of these compressors is net hydrogen-rich gas from the Pacol process. Both dry compressors have shown similar problems in the first and second stages. The simultaneous rise in the cylinder temperature and decrease in the flow has forced shut-down of the compressors for the next actions in the process. Initial inspections have revealed some kind of deposits covered the cylinder and its components. The valves, liquid tested and results have shown significant leakage of all the suction and discharge valves of the cylinders. Moreover, the thickness of all piston rings have decreased up to 50 percent which is more than allowable values. The compositions of deposits, tested by X-ray fluorescence (XRF) and X-ray diffraction (XRD), result from the analysis shown that it contains 35.2 percent (mass fractions) of Chlorine and 27.5 percent of Iron, and noticeable amount of Sulfur or Phosphor. XRD analysis has reported that the Iron Chloride Hydrate is the main part of the fouling sample. In this paper, the impact of the aforementioned chemicals on the compressor components are investigated, and some approaches are proposed to absorb or inhibit these chemicals.
Basic design procedure for an internally geared screw compressor
Authors: Read Matthew
Published: September 2021

The internally geared gerotor type of positive displacement machine is widely used for pumping applications, but can also be used to achieve internal compression or expansion of a working fluid. A further development of this configuration is the application of helical twist to the inner and outer rotors. Previous studies have shown that this can decrease the power transferred between rotors, and increase the relative maximum flow areas at the inlet and discharge ports. There are possible benefits to this configuration when compared to conventional twin-screw machines, including reduced leakage area, stiffer rotors, and co-directional thermal expansion of rotors. However, no experimental data is currently available for this configuration, and optimising the geometry of the gerotor screw machine requires a detailed understanding of the porting, leakage flows and mechanical losses. An experimental programme is being conducted to investigate the influence of these factors on performance. This paper discusses preliminary results from geometrical analysis leading to a simple design procedure. The basic design of an internally geared air compressor is demonstrated, based on the operation characteristics of a conventional twin screw machine.
A study on the kinematics of a new Schukey-type rotary compressor
Authors: Cui B , Becker K , Lüdersen U , Gottschlich M , Kabelac S
Published: September 2021

A new type of rotary compressor, called “rotary-chamber compressor”, consists of two interlocking rotors with 4 wings each, that perform non-uniform rotary movements. Both rotors have the same direction of rotation, while one rotor is accelerating, the other rotor is retarding. After surpassing a specific mark, the sequence changes and the leading rotor begins to retard and vice versa. Due to the resulting relative phase difference, the volume between the two wings is changing periodically, which allows pulsating working chambers. The technology was first introduced by its founder Jürgen Schukey in 1987. Since then, no further development on this machine is known to us except our own. In this contribution, a study on the kinematics of the rotary-chamber-compressor is presented. Initial studies have shown that changes in the kinematics of the rotors will have a direct influence on the thermodynamical variables, which, if optimized, can lead to an increased performance of the machine. Therefore, a mathematical model has been developed to obtain the performance parameters from different kinematic concepts by using numerical CFD analysis. Furthermore, additional optimization possibilities will be listed and discussed.
Time parametrizations in long-range interacting Bose-Einstein condensates
Authors: Konishi Eiji
Published: September 2021

Time-reparametrization invariance in general relativistic space-time does not allow us to single out a time in quantum mechanics in a mechanical way of measurement. Motivated by this problem, we examine this gauge invariance in the ground state of the quasi-stationary coarse-grained state of a long-range interacting closed system of identical or identified, macroscopic, and spatiotemporally inhomogeneous Bose–Einstein condensates in the thermodynamic and Newtonian limits. As a result, we find that it is a theoretical counterexample of this gauge invariance, except for proper-time translational invariance, at a coarse-grained level.
Associations of Family Distress, Family Income, and Acculturation on Pediatric Cognitive Performance Using the NIH Toolbox: Implications for Clinical and Research Settings
Authors: Thompson Ryan C , Montena Alexandra L , Liu Kevin , Watson Jessica , Warren Stacie L
Published: September 2021

Objective

There is a growing recognition that the use of conventional norms (e.g., age, sex, years of education, race) as proxies to capture a broad range of sociocultural variability on cognitive performance is suboptimal, limiting sample representativeness. The present study evaluated the incremental utility of family income, family conflict, and acculturation beyond the established associations of age, gender,maternal years of education, and race on cognitive performance.

Method

Hierarchical linear regressions evaluated the incremental utility of sociocultural factors on National Institutes of Health Toolbox in a nationally representative sample of pre-adolescent children (n = 11,878; Mage = 10.0 years; Adolescent Brain Cognitive Development Study). A regression-based norming procedure was implemented for significant models. Paired sample t-tests were used to compare original and newly created demographically corrected T-scores.

Results

Nearly all regression models predicted performance on the NIH-TB subtests and composite scores (p < .005). Greater family income and lower family conflict predicted better performance, although the effect sizes were small by traditional standards. Acculturation scores did not explain additional variance in cognitive performance. Lastly, there were no significant differences between the original and newly created demographically corrected T-scores (Mdiff < 0.50).

Conclusions

The present study highlights that, although family income, family conflict, and acculturation have been shown to routinely influence cognitive performance in preadolescent children, the NIH-TB appears to be highly robust to individual differences in sociocultural factors in children between ages 9 and 10. Contextual and temporal implications of the present results are discussed.
Effects of chronic and acute predation risk on sexual ornamentation and mating preferences
Authors: Frommen Joachim G , Thünken Timo , Santostefano Francesca , Balzarini Valentina , Hettyey Attila
Published: September 2021

Phenotypic plasticity is widespread in animals. Still, how plastic responses to predator presence affect traits under sexual selection and influence mating preferences is not well understood. Here, we examined how simulated chronic predator presence during development and acute predator presence during mate choice affect the expression of male secondary sexual traits and female mating preference in the three-spined stickleback, Gasterosteus aculeatus. Males reared under chronic predator presence developed less intense red breeding coloration but showed higher courtship activity than males that grew up in a predator-free environment. Acute predator presence during mate choice trials did not influence male behavior or ornamentation. Predator presence experienced during development did not affect female mating preferences, whereas acute predator presence altered preferences for male courtship activity. Male body size and eye coloration influenced the intensity of female mating preferences, while the trait changing most in response to predator presence during development (red coloration) had no significant impact. The observed interplay between developmental plasticity in male ornamental traits and environment-dependent female mating preferences may lead to dynamic processes altering the strength and direction of sexual selection depending on both the chronic and acute risk of predation. These processes may contribute to the maintenance of within- and among-population variation in secondary sexual traits, and may, ultimately, facilitate speciation.
Cross talk: trafficking and functional impact of maternal exosomes at the feto-maternal interface under normal and pathologic states
Authors: Tantengco Ourlad Alzeus G , Radnaa Enkhtuya , Shahin Hend , Kechichian Talar , Menon Ramkumar
Published: September 2021

Fetal cell-derived exosomes promote inflammation in uterine and cervical cells to promote labor and delivery. However, the effect of maternal exosomes on fetal cells is still not known. We tested the hypothesis that cervical cells exposed to infectious and oxidative stress (OS) signals produce exosomes that can induce inflammation at the feto-maternal interface (FMi). Exosomes isolated from medium samples from human ectocervical epithelial cells (ecto), endocervical epithelial cells (endo), and cervical stromal cells (stroma) in normal cell culture (control) or exposed to infection or OS conditions were characterized based on morphology, size, quantity, expression of tetraspanin markers, and cargo proteins. Human decidual cells, chorion trophoblast cells (CTC), chorion mesenchymal cells (CMC), amnion mesenchymal cells (AMC), and amnion epithelial cells (AEC) were treated with control, LPS-, or OS-treated cervical exosomes. Enzyme-linked immunosorbent assay for pro-inflammatory cytokines and progesterone was done to determine the recipient cells’ inflammatory status. Ecto, endo, and stroma released ∼110 nm, cup-shaped exosomes. LPS and OS treatments did not affect exosome size; however, OS significantly increased the number of exosomes released by all cervical cells. Cervical exosomes were detected by fluorescence microscopy in each target cell after treatment. Exosomes from LPS- and CSE-treated cervical cells increased the inflammatory cytokine levels in the decidual cells, CMC, AMC, and AEC. LPS-treated stromal cell exosomes increased IL-6, IL-8, and progesterone in CTC. In conclusion, infection and OS can produce inflammatory cargo-enriched cervical exosomes that can destabilize FMi cells. However, the refractoriness of CTC to exosome treatments suggests a barrier function of the chorion at the FMi.
Unravelling distribution patterns of Neotropical lianas: an analysis of endemicity of tribe Bignonieae (Bignoniaceae)
Authors: Narváez-Gómez Juan Pablo , Szumik Claudia A , Goloboff Pablo A , Lohmann Lúcia G
Published: September 2021

Areas of endemism characterize geographical regions by their unique biotas, providing the basis for studies on the ecological and historical drivers of these biologically distinct units. Tribe Bignonieae (Bignoniaceae) are a highly diverse clade of lianas distributed throughout the Neotropics, representing an excellent model for studying the drivers of species diversity and distribution patterns in this region. We used a dataset representing 98% of the diversity of Bignonieae and 21 170 unique locality records to perform an analysis of endemicity using NDM/VNDM. We recovered areas of endemism distributed across the Neotropics, including a higher number of areas at coarser spatial scales. Although overlapping and nested patterns of endemism were common and the spatial congruence with the individual units of previous regionalization schemes was low, the patterns of endemism recovered were in general agreement with those documented for other taxa. Our findings are generally consistent with key Neotropical biogeographical hypotheses. These results highlight the importance of studying detailed distribution patterns of selected taxa for an improved understanding of Neotropical biogeography.
Elevated Dopamine Synthesis as a Mechanism of Cognitive Resilience in Aging
Authors: Ciampa Claire J , Parent Jourdan H , Lapoint Molly R , Swinnerton Kaitlin N , Taylor Morgan M , Tennant Victoria R , Whitman A J , Jagust William J , Berry Anne S
Published: September 2021

Aging is associated with declines in multiple components of the dopamine system including loss of dopamine-producing neurons, atrophy of the dopamine system’s cortical targets, and reductions in the density of dopamine receptors. Countering these patterns, dopamine synthesis appears to be stable or elevated in older age. We tested the hypothesis that elevation in dopamine synthesis in aging reflects a compensatory response to neuronal loss rather than a nonspecific monotonic shift in older age. We measured individual differences in striatal dopamine synthesis capacity in cognitively normal older adults using [18F]Fluoro-l-m-tyrosine positron emission tomography cross-sectionally and tested relationships with longitudinal reductions in cortical thickness and working memory decline beginning up to 13 years earlier. Consistent with a compensation account, older adults with the highest dopamine synthesis capacity were those with greatest atrophy in posterior parietal cortex. Elevated dopamine synthesis capacity was not associated with successful maintenance of working memory performance overall, but had a moderating effect such that higher levels of dopamine synthesis capacity reduced the impact of atrophy on cognitive decline. Together, these findings support a model by which upregulation of dopamine synthesis represents a mechanism of cognitive resilience in aging.
Optimized Method for Determination 57 Volatile Organic Compounds in Nitrogen Using GC × GC–FID
Authors: Yang Jing , Du Jian , Huang Wei , Ning Hongbing , Li Ning
Published: September 2021

The sample containing 57 volatile organic compounds (VOCs) in nitrogen at a nominal 1 ppmv was prepared in our lab using weighting method. A methodology for determination of the 57 VOCs using a two-dimensional gas chromatography equipped with Deans switches and two flame ionization detectors (GC × GC–FID) was developed and validated for resolution, asymmetry, sensitivity, precision (intra-day precision and inter-day precision), linearity, limit of detection (LOD), limit of quantification (LOQ) and accuracy. In this study, resolution, asymmetry and sensitivity of the analytical method were improved，intra-day precisions of all the compounds were <1% and inter-day precisions were between 0.9 and 3.0%. In addition, LOQ and LOD were in the range of 0.024–0.185 ppmv and 0.012–0.092 ppmv, respectively. An excellent linearity was obtained (R2 > 0.9995). At the meantime, the accuracy of the analytical method was evaluated by determining the concentration of a certified reference material.