Cold Buffer Research Articles

Observation of the Infrared-Induced Structural Change in the Microscopic Hydrogen Bond Network of Phenol-Methanol Cluster Cations in a Cold-Ion Trap.

To gain insight into microscopic hydrogen bond networks, we measured ultraviolet photodissociation (UVPD) spectra of the phenol-methanol 1:3 cluster cation, [PhOH(MeOH)3]+ trapped in a variable temperature ion trap. At low temperatures, an isomer with a ring-type hydrogen bond structure dominates, whereas at higher temperatures the chain-type isomers become dominant due to the flexibility of their hydrogen bond structures. We also found a clear temperature dependence of the spectral features, such as band position and width. In addition to the above measurement, we observed the infrared (IR) induced isomerization of [PhOH(MeOH)3]+ to study the dynamical aspects of hydrogen bond networks. We succeeded in observing IR-induced isomerization from the ring to chain forms of [PhOH(MeOH)3]+ at low temperature. The isomerization was clearly identified as a change in the UVPD spectra. The time evolution of the UVPD spectra after IR excitation indicated that the IR-induced isomerization occurs within a nanosecond. The chain-type isomers produced by the IR-induced isomerization are then converted back to the ring-type form by collisions with cold He buffer gas in the trap. This backward isomerization proceeds with a time constant of 100 μs under our experimental conditions. In this study, we evaluated the temperatures of the chain isomers during the backward isomerization on the basis of the spectral features.

A hybrid mechanism of 3D optical trapping of particles immersed in a cold buffer gas

A novel mechanism of the formation of a deep optical superlattice (OSL) for three-dimensional (3D) trapping of resonant impurity atoms immersed in a transparent cold buffer gas is proposed and investigated theoretically. This mechanism is associated with the joint action of two factors of different physical nature: rectification effect of the gradient force of light pressure and effect of the light induced drift (LID) of atoms (a consequence of the difference in gas-kinetic cross sections of excited and unexcited atoms). Such a situation can be realised when a gas mixture is irradiated by a bichromatic combined light beam which is a special coaxial superposition of cosine-Gaussian optical beams. Here, the RcGF creates a periodic 1D array of deep potential wells (OSL) along the beam axes, and an effective force, causing LID, pulls resonant particles into the combined light beam and provides their transverse (with respect to the beam axes) confinement in OSL. As a result, there can occur a giant accumulation of impurity particles in the OSL cells, accompanied by a strong spatial particle localization far away from the walls of the reservoir, in which the gas mixture is located.

Nuclear Spin Relaxation in Cold Atom-Molecule Collisions.

We explore the quantum dynamics of nuclear spin relaxation in cold collisions of 1Σ+ molecules with structureless atoms in an external magnetic field. To this end, we develop a rigorous coupled-channel methodology, which accounts for rotational and nuclear spin degrees of freedom of 1Σ+ molecules and their interaction with an external magnetic field as well as anisotropic atom-molecule interactions. We apply the methodology to study the collisional relaxation of the nuclear spin sublevels of 13CO molecules immersed in a cold buffer gas of 4He atoms. We find that nuclear spin relaxation in the ground rotational manifold (N = 0) of 13CO occurs extremely slowly due to the absence of direct couplings between the nuclear spin sublevels. The rates of collisional transitions between the rotationally excited (N = 1) nuclear spin states of 13CO are generally much higher due to the direct nuclear spin-rotation coupling between the states. These transitions obey selection rules, which depend on the values of space-fixed projections of rotational and nuclear spin angular momenta (MN and MI) for the initial and final molecular states. For some initial states, we also observe a strong magnetic field dependence, which can be understood by using the first Born approximation. We use our calculated nuclear spin relaxation rates to investigate the thermalization of a single nuclear spin state of 13CO(N = 0) immersed in a cold buffer gas of 4He. The calculated nuclear spin relaxation times (T1 ≃ 1 s at T = 1 K at a He density of 10-14 cm-3) display a steep temperature dependence decreasing rapidly at elevated temperatures due to the increased population of rotationally excited states, which undergo nuclear spin relaxation at a much faster rate. Thus, long relaxation times of N = 0 nuclear spin states in cold collisions with buffer gas atoms can be maintained only at sufficiently low temperatures (kBT ≪ 2Be), where Be is the rotational constant.

Subtle Intricacies Identified during Streptozotocin-Induced Diabetes in Wistar Rats

Abstract: Aim: This study aimed to establish the dose of streptozotocin required to induce Type -1 diabetes in Wistar rats. Background: Streptozotocin is currently employed worldwide to induce insulin-dependent diabetes mellitus also known as Type 1 diabetes mellitus in experimental animals. Though many reports on the use of streptozotocin induction of diabetes are reported in the literature, they were not reproducible. Moreover, there was no mention of the mortality associated with the same as well as the conditions followed during the study. Materials and Methods: In the present study, the dose, route, and solvent used for streptozotocin were investigated. Various doses of streptozotocin 55, 50, 40, and 35mg/kg dissolved in either freshly prepared cold 10mM sodium citrate buffer (pH 4.5) or normal saline solution was administered intraperitoneally as well as intravenously. For intraperitoneal administration, the dose-volume was 10mL/kg whereas for intravenous administration the dose-volume was 2mL/Kg. Different routes were employed to ascertain the cause of mortality for which an autopsy was performed. Besides mortality rate was also determined. Results and Discussion: The findings of the study revealed that a 35-40mg/kg dose of streptozotocin showed less percentage mortality and successful induction of diabetes. Conclusion: Mortality (10-20%) was observed at a dose of 35-40mg/kg streptozotocin. Therefore, streptozotocin (35-40mg/kg) was confirmed to be safe and effective for the induction of diabetes in Wistar rats. This paper highlights subtle intricacies observed during induction of diabetes in Wistar rats using streptozotocin Keywords: Male Wistar rats, Streptozotocin, Type-1 diabetes, 5% dextrose, Mortality, Normal saline solution.

Experimental investigation and analysis on the pressure stabilization of subcooled liquid nitrogen circulation for the HEPS

The High Energy Photon Source (HEPS) is a fourth generation radiation source, where lots of optical equipment are cooled down to the liquid nitrogen temperature for the better performance. The subcooled liquid nitrogen circulation is a very advantageous cooling method of monochromators and undulators, which are sensitive to fluid pressure fluctuations. Although the pressure stabilization matters a lot but it has rarely been studied. In this paper, the causes of pressure fluctuations are analyzed, and accordingly the principle of thermal balance is proposed. Based on the analysis, three pressure stabilization methods were suggested and tested. A partially liquid nitrogen filled tank was connected to the subcooled liquid nitrogen circulation serving as a pressure fluctuation buffer. The side effect is that the heat load of the tank raises the pressure gradually. Therefore, the cold source buffer and its induced heat load need good compromise. The tank heat load was cooled by saturated nitrogen, bypass liquid nitrogen and direct gas absorption: The saturated nitrogen reuses the sensible heat of cold gas; the bypass liquid nitrogen avoids the influence of circulation heat load variation and the gas absorption prevents the heat exchanger in the tank. The test results show that the peak-to-peak value of the pressure fluctuation can be controlled in the level of ± 4.0 mbar and the RMS value less than 1.0 mbar. The pressure affect factors were empirically studied.

High-resolution spectroscopy of the X [formula omitted] A[formula omitted], C[formula omitted] transitions of PbO in 22 300–25 100 cm-1

High-resolution excitation spectra of the X0+→ A0+ and X0+→ C0+ transitions of lead monoxide (PbO) are observed in a range of 22 300-25 100 cm−1. Transition frequencies are determined with an average uncertainty of 8.5×10−4 cm−1 by comparing with resonances of an ultralow expansion etalon. PbO molecules are produced by laser ablation in a cold helium buffer gas, which provides rotationally cold but vibrationally hot molecules and allows observation of hot bands of excitation from the υ′′=1,2 vibrational states. Spectroscopic constants and potential curves for the A0+ and C0+ states are determined, and the spectroscopic constants obtained for the three main isotopologues are reproduced to a satisfactory level using a single potential curve for each electronic state. This indicates that perturbation due to other electronic states is negligibly small.

A New Mechanism for Sympathetic Cooling of Atoms and Ions in Atomic and Ion-Atomic Traps

Sympathetic cooling of a Fermi gas with a buffer gas of bosonic atoms is an efficient way to achieve quantum degeneracy in Fermi systems. However, all attempts to use this method for cooling ions until recently were ineffective because of the unremovable ion `"micromotion" in electromagnetic Paul traps, which prevents the realization of a number of hot projects with cold atom-ion systems. In this regard, we propose a new efficient method for sympathetic cooling of ions: the use for this purpose of cold buffer atoms in the region of atom-ion confinement-induced resonances (CIRs) [V.S. Melezhik, Phys. Rev. A103, 53109 (2021)]. We show that the destructive effect of "micromotion" on its sympathetic cooling can, however, be suppressed in the vicinity of the atom-ion CIR. Here, the resonant blocking of a close collision of an atom with an ion also resists its heating due to "micromotion". We investigate the effect of sympathetic cooling around CIRs in atom-ion, and atom-atom confined collisions within the quantum-quasiclassical approach using the Li-Yb$^+$ and Li-Yb confined systems as an example. In this approach, the Schr\"odinger equation for a cold light atom is integrated simultaneously with the classical Hamilton equations for a hotter heavy-ion or atom during a collision. We have found the region near the atom-ion CIR where the sympathetic cooling of the ion by cold atoms is possible in a hybrid atom-ion trap. We also show that it is possible to improve the efficiency of sympathetic cooling in atomic traps by using atomic CIRs.

THE EFFECT OF PLACENTAL CRYOEXTRACT ON THE STATE OF PROTEIN-LIPID METABOLISM IN THE GASTRIC MUCOSA IN EXPERIMENTAL STRESS-INDUCED ULCERS

Introduction. Peptic ulcer is one of the most prevalent diseases of the gastrointestinal tract. Stress factor is considered to have the highest impact on the development of ulcers, as it is present in almost all cases of onset and exacerbation of this disease. Acute stress ulcers occur with severe injuries, acute diseases of various organs, shock, a sharp drop in blood pressure, oxygen deficiency of body tissues, liver, kidney and others. Given the above facts, in the correction of stress-induced lesions of the gastric mucosa (GM) therapeutically, the target should consider not only reducing the aggression factors of gastric juice, but also the normalization of changes in protein and carbohydrate metabolism in GM. In this aspect, our attention was drawn to the domestic biotechnological preparation of placental cryoextract (CEP), which has a range of valuable biological effects. The aim is to study the effect of cryopreserved placenta extract on the state of protein-lipid metabolism in the gastric mucosa in a model of water-immobilization stress in rats. Materials and methods of research. The studies were performed on 28 nonlinear laboratory male rats weighing 200–220 g. Stress-induced gastric ulcer was modeled under water-immobilization stress (WIS) in rats according to the method of Takagi et al. To obtain the homogenate, the GM was perfused with cold (+ 4°C) buffer solution and homogenized at 3000 rpm (teflon/glass). The content of oxidatively modificated proteins (OMP) in GM was determined by Dubinina spectrophotometric method. The content of total lipids in the GM was determined spectrophotometrically by color reaction with sulfophosphovaniline reagent. Phospholipids (PL) were fractionated by the method of Svetashev and Vaskovsky. Research results. Evaluation of changes in protein metabolism in GM showed that the level of total protein in rats, which were preventively administered CEP before WIS, was almost comparable with that of intact rats, i.e., 50.1 ± 1.7 μg/mg tissue and 51.1 ± 1.3 μg/mg of tissue, respectively, which indicated the elimination of disorders of protein homeostasis with the introduction of the studied cryoextract. Studies of changes in total lipids and PL showed that the content of PL of animals treated with CEP was 26.9 ± 0.9%, which was not significantly different from that of intact animals (30.5 ± 0.9%) and, at the same time, it was by 7.3% higher (p < 0.001) as compared with animals who were administered esomeprazole. Conclusions. Prophylactic five-day administration of CEP to WIS leads to normalization of all evaluated indices, in particular, to increase of the total protein level by 29.0% (p <0.01), decrease of oxidatively modified proteins level by 20.6% (p <0.01), and the 2.3-fold increase (p <0.001) of the level of phospholipids in the total lipids pool.

Discharge formation in a copper vapor laser: optimal pumping conditions

The electrophysical process in the discharge circuit of a copper vapor laser (CVL) is investigated. It is shown that the pumping of the active medium of a CVL in gas-discharge tubes (GDT) with electrodes located in cold buffer zones is carried out in two stages. At the first (preparatory) stage, the capacitive components of the laser discharge circuit are charged from the storage capacitor, and at the second stage, the active medium is directly pumped. The transition from the preparatory stage to the pumping stage is carried out as a result of a breakdown. It is shown that breakdown is a transient process of discharge development from a glowing to a non-thermal arc discharge and is characterized by a sharp change in the cathode potential drop across the GDT. The inductance of the discharge circuit is a factor that determines the efficiency of pumping the active medium since the release of the energy stored in the inductance at the preparatory stage provides heating of the cathode spot and determines the conditions for the occurrence of thermal emission of electrons from the GDT cathode.

Primary energy saving potential of a solar-driven ejector cooling system: a case study for a Portuguese residential building

The seasonal energy performance of a cooling system based on an innovative variable-geometry ejector (VGE) is numerically investigated by using TRNSYS. The VGE-based system is mainly driven by solar energy, collected through solar thermal collectors, and is coupled to a residential building located in Porto. A biomass boiler is used as back-up heater. The energy performance of the investigated cooling system is compared with that of a conventional solution, based on a commercial air-to-water chiller. Results point out that, almost 75% of the generator heat demand can be supplied by solar collectors and about 90% of the overall energy input of the ejector-based system is satisfied by renewables. Moreover, numerical simulations confirm how the capability to vary the ejector geometry on the basis of current operating conditions allows to strongly improve the ejector seasonal efficiency. A second series of simulations aimed to further enhance the system performance. A master control logic which extends the VGE operation time in correspondence of favourable ambient conditions was introduced, in order to store additional cooling energy in the cold buffer tank. This strategy has proved to be effective, since the energy consumption of the biomass boiler could be reduced up to 35%.

Organotypic Slice Cultures as Preclinical Models of Tumor Microenvironment in Primary Pancreatic Cancer and Metastasis.

Realistic preclinical models of primary pancreatic cancer and metastasis are urgently needed to test the therapy response ex vivo and facilitate personalized patient treatment. However, the absence of tumor-specific microenvironment in currently used models, e.g., patient-derived cell lines and xenografts, only allows limited predictive insights. Organotypic slice cultures (OTSCs) comprise intact multicellular tissue, which can be rapidly used for the spatially resolved drug response testing. This protocol describes the generation and cultivation of viable tumor slices of pancreatic cancer and its metastasis. Briefly, tissue is casted in low melt agarose and stored in cold isotonic buffer. Next, tissue slices of 300 µm thickness are generated with a vibratome. After preparation, slices are cultured at an air-liquid interface using cell culture inserts and an appropriate cultivation medium. During cultivation, changes in cell differentiation and viability can be monitored. Additionally, this technique enables the application of treatment to viable human tumor tissue ex vivo and subsequent downstream analyses, such as transcriptome and proteome profiling. OTSCs provide a unique opportunity to test the individual treatment response ex vivo and identify individual transcriptomic and proteomic profiles associated with the respective response of distinct slices of a tumor. OTSCs can be further explored to identify therapeutic strategies to personalize treatment of primary pancreatic cancer and metastasis.

Improving efficiency of sympathetic cooling in atom-ion and atom-atom confined collisions

We propose a new way for sympathetic cooling of ions in an electromagnetic Paul trap: it implies the use for this purpose of cold buffer atoms in the region of atom-ion confinement-induced resonance (CIR). The problem is that the unavoidable micromotion of the ion and the long-range nature of its interaction with the environment of colder atoms in a hybrid atomic-ion trap prevent its sympathetic cooling. We show that the destructive effect of ion micromotion on its sympathetic cooling can however be suppressed in the vicinity of the atom-ion CIR. The origin of this is the "fermionization" of the atom-ion wave function near CIR, where the atom-ion pair behaves as a pair of noninteracting identical fermions. This prevents the complete approach of the atom with the ion near resonance and does not enhance the ion micromotion, which interferes with its sympathetic cooling. We investigate the effect of sympathetic cooling around CIRs in atom-ion and atom-atom confined collisions within the qusiclassical-quantum approach using the Li-Yb$^+$ and Li-Yb confined systems as an example. In this approach, the Schr\"odinger equation for a cold light atom is integrated simultaneously with the classical Hamilton equations for a hotter heavy ion or atom during collision. We have found the region near the atom-ion CIR where the sympathetic cooling of the ion by cold atoms is possible in a hybrid atom-ion trap. We also show that it is possible to improve the efficiency of sympathetic cooling in atomic traps by using atomic CIRs.

Functional flow cytometry of monocytes for routine diagnosis of innate primary immunodeficiencies

Functional flow cytometry of monocytes for routine diagnosis of innate primary immunodeficiencies

The Hexose efflux from the peeled grape berry

Aim: The transport of sugars into grape berry mesocarp cells across the plasma and vacuolar membranes after onset of ripening is a complex process. Elements of the sugar transport mechanism may be assessed by exposing the mesocarp cells and investigating sugar movement across the membranes. The purpose of this study was to gain insights into the nature of the transport mechanism by creating conditions conducive to hexose efflux from the peeled berry.Methods and results: The experimental technique employed was a derivate of the ‘berry-cup’ technique. The skin of ripening cv. Shiraz berries was peeled in situ and, after an initial wash, hexose efflux into a collection medium (MES buffer) was monitored. Additionally, during the period of intensive sugar accumulation (one week after veraison) and two weeks later, hexose efflux was assessed following three modifications: (i) using berries excised from the vine, (ii) using MES buffer (2-(N-morpholino)ethanesulfonic acid, pH 5.5) containing PCMBS (p-chloromercuribenzenesulfonic acid, 1mM), and (iii) using cold (10°C) or warm (40°C) MES buffer. Hexose quantities collected into the buffer were dependent on ripening stage and buffer temperature, but they were not dependent on an intact berry-to-cluster connection. The inhibitory effect of PCMBS was observed early in ripening, but not two weeks later.Conclusions: These results lead us to the conclusion that the origin of the collected hexoses was vacuolar as opposed to vascular, and that the hexose efflux mechanism is differently sensitive to PCMBS at the two stages of ripening.Significance and impact of the study: This simple technique was effective at providing insights into hexose transport within the grape berry at the cellular level.

Performance of a demonstration solar PVT assisted heat pump system with cold buffer storage and domestic hot water storage tanks

The design and demonstration of a solar PVT assisted - heat pump system with a cold buffer storage tank on the source side of the heat pump and a hot storage tank for domestic hot water preparation is presented. The system was subject to real weather conditions and hot water draw offs. Measurements over nine months are presented and analyzed. The focus was on the thermal dynamic of the system and the interplay between the heat pump, the storage tanks and the thermal absorber of the uninsulated PVT panel. The hot water demand was almost completely covered by the thermal part of the PVT collector in sunny summer periods. In less sunny periods, the brine-water heat pump recharged the hot water tank after draw offs and discharged the buffer storage tank. The uninsulated PVT collector worked as an energy absorber and was able to extract heat form the ambient air and recharge the buffer storage tank to the ambient air temperature when no solar irradiance was available. In the less sunny and colder periods, the PVT added a significant amount of energy to the cold storage tank.

Uji Aktivitas Lektin Biji Kebiul terhadap Kecepatan Penggumpalan Sel Darah Merah Manusia dalam Kondisi Patologis dan Implementasinya sebagai Modul Pembelajaran Kimia

ABSTRACT[Lectin activities of kebiul seeds to the red blood cell agglutination speed in pathological condition and its implementation as a chemical learning module]. The purposes of this research were to determine: 1) the relative moleculer mass protein that behaves as a lectin in the seed extract kebiul , 2) the velocity of red blood cell clumping influenced by seed lectin kebiul, 3) know the difference student results on protein taught modules and a without modules taught at the College of Teacher Training and Education Teachers Association of the Republic of Indonesia (STKIP-PGRI) Lubuklinggau. Extraction of seeds Kebiul carried out in the a cold buffer solution with pH 7.4 and plus 60% saturated ammonium sulfat (salting out method), and made in four concentrations, namely : 2%, 4%, 6% and 8%. Then tested the activity of seed lectin kebiul to speed clotting of human red blood cells in pathological conditions. To determine the relative molecular mass protein that behaves as a lectin in the seed extract kebiul SDS PAGE electrophoresis performed 1-D. The experiment were then implemented on the material of protein biochemistry using modules. The results of the research showed that on the concentration of 8% the velocity of the clumping of a human red blood cells hypertension most of the highest, the relative molecular mass which behaves as a lectin protein electrophoresis results of 1-D SDS PAGE obtained by a three protein bands in the range of moleculer weights 80, 128 and 144 kDa. The Results of the implementation of the experimental class showed an average `post test value was 95 and the post test control class 69.41. There are differences in students' learning about protein for students who are taught by module and who are taught without module.Keywords: Lectin; agglutination; blood; 1-D SDS PAGE; learning outcomes.

Uji Aktivitas Lektin Biji Kebiul terhadap Kecepatan Penggumpalan Sel Darah Merah Manusia dalam Kondisi Patologis dan Implementasinya sebagai Modul Pembelajaran Kimia

ABSTRACT[Lectin activities of kebiul seeds to the red blood cell agglutination speed in pathological condition and its implementation as a chemical learning module]. The purposes of this research were to determine: 1) the relative moleculer mass protein that behaves as a lectin in the seed extract kebiul , 2) the velocity of red blood cell clumping influenced by seed lectin kebiul, 3) know the difference student results on protein taught modules and a without modules taught at the College of Teacher Training and Education Teachers Association of the Republic of Indonesia (STKIP-PGRI) Lubuklinggau. Extraction of seeds Kebiul carried out in the a cold buffer solution with pH 7.4 and plus 60% saturated ammonium sulfat (salting out method), and made in four concentrations, namely : 2%, 4%, 6% and 8%. Then tested the activity of seed lectin kebiul to speed clotting of human red blood cells in pathological conditions. To determine the relative molecular mass protein that behaves as a lectin in the seed extract kebiul SDS PAGE electrophoresis performed 1-D. The experiment were then implemented on the material of protein biochemistry using modules. The results of the research showed that on the concentration of 8% the velocity of the clumping of a human red blood cells hypertension most of the highest, the relative molecular mass which behaves as a lectin protein electrophoresis results of 1-D SDS PAGE obtained by a three protein bands in the range of moleculer weights 80, 128 and 144 kDa. The Results of the implementation of the experimental class showed an average `post test value was 95 and the post test control class 69.41. There are differences in students' learning about protein for students who are taught by module and who are taught without module.Keywords: Lectin; agglutination; blood; 1-D SDS PAGE; learning outcomes.

Fuelwood resources and their use pattern by Bhotia community in Niti valley, Western Himalaya

The local communities of the Himalaya have been using fuel wood as one of the major sources of energy since millennia. Their dependency on these resources as primary source of fuel wood has resulted in unsustainable pressures on the forests. The present communication aims to access the fuel wood resource and consumption pattern of Bhotia, an ethnic community in a cold arid and buffer zone of Nanda Devi Biosphere Reserve, i.e. Niti valley in the Western Himalaya. Within the Niti valley, 87 households in six villages were surveyed using open and close-ended structured questionnaire. Use Index (I%) of each fuel wood species was calculated to evaluate the key species used by the inhabitants and their preferences. The study revealed use of 10 species for fuel wood (five species each of tree and shrub) by the Bhotias. Pinus wallichiana (I = 96.6%) followed by Cedrus deodara (93.1%) were the preferred tree species for fuel wood, while among shrubs, Juniperus indica and J. communis were extensively used. Fuel wood consumption in the Niti valley was much lower (1.6±0.2 kg household-1 day-1) than other villages in the Greater Himalaya (4.9±0.4 kg household-1 day-1). The seasonally employed which formed 23% of the surveyed households, collected almost twice as much fuel wood than the employed households (9.2±0.4 and 5.2±0.4 quintals season-1, respectively). As the area is characterized by sparse vegetation cover, low primary productivity and short growing season, and is thus highly susceptible to irreversible changes of natural habitats. The study suggests that providing alternate and non-conventional energy sources such as solar cookers and fuel efficient portable ovens to the inhabitants at subsidized rates could reduce the pressure on nearby forests. Botanica Orientalis – Journal of Plant Science (2017) 11: 1–6

Impact of euthanasia, dissection and postmortem delay on metabolic profile in mouse retina and RPE/choroid

Metabolomics studies in the retina and retinal pigment epithelium (RPE) in animal models or postmortem donors are essential to understanding the retinal metabolism and to revealing the underlying mechanisms of retinal degenerative diseases. We have studied how different methods of euthanasia (CO2 or cervical dislocation) different isolation procedures and postmortem delay affect metabolites in mouse retina and RPE/choroid using LC MS/MS and GC MS. Compared with cervical dislocation, CO2 exposure for 5 min dramatically degrades ATP and GTP into purine metabolites in the retina while raising intermediates in glucose metabolism and amino acids in the RPE/choroid. Isolation in cold buffer containing glucose has the least change in metabolites. Postmortem delay time-dependently and differentially impacts metabolites in the retina and RPE/choroid. In the postmortem retina, 18% of metabolites were changed at 0.5 h (h), 41% at 4 h and 51% at 8 h. However, only 6% of metabolites were changed in the postmortem RPE/choroid and it steadily increased to 20% at 8 h. Notably, both postmortem retina and RPE/choroid tissue showed increased purine metabolites. Storage of eyes in cold nutrient-rich medium substantially blocked the postmortem change in the retina and RPE/choroid. In conclusion, our study provides optimized methods to prepare fresh or postmortem retina and RPE/choroid tissue for metabolomics studies.

Bromelain Activity of Waste Parts of Two Pineapple Varieties

Bromelain, a protease found in pineapples, is of high demand in the pharmaceutical, cosmetic and food industries. Along the pineapple processing chain, waste products such as peels, crowns, stems and cores result. These parts are usually discarded, though they contain significant amounts of the enzyme bromelain. This study sought to determine the bromelain activity of the crowns and peels of two pineapple varieties grown in Ghana;MD2andSugarloaf. The crude extract was obtained by homogenising the peels and crowns in a cold phosphate buffer and centrifuging at 3000 rpm for 15 min. Ethanol and ammonium sulphate precipitation were carried out on the extract between 30% – 80% precipitation levels. The enzyme activity was determined using the casein digestion method. Results showed that bromelain was precipitated mainly in the 30% – 60% precipitation range.Sugarloafcrowns yielded the highest enzyme activity of 20.82 U/ml and a specific activity of 194.58 U/mg at the 40% ammonium sulphate precipitation level. This was followed by theSugarloafpeels with an enzyme activity of 19.98 U/ml at 50% ethanol precipitation level. Ethanol precipitation resulted in fractions with lower bromelain activity. Enzyme activity was higher in theSugarloafvariety and also in the crowns of both varieties. The two pineapple varieties have significant levels of bromelain activity and could be exploited for commercialisation.