Positional Distribution Research Articles

Influence of Dietary Triacylglycerol Structure on the Accumulation of Docosahexaenoic Acid [22:6(n-3)] in Organs in a Short-Term Feeding Trial with Mildly Omega-3 Deficient Rats.

To study the effect of positional distribution of docosahexaenoic acid (DHA) in dietary triacylglycerols (TAG) on the tissue fatty acid content and composition of mildly (n-3) deficient rats. In a 5-day feeding trial, mildly (n-3) deficient rats received 360mg daily structured TAGs: sn-22:6(n-3)-18:0-18:0, sn-18:0-18:0-22:6(n-3), sn-18:0-22:6(n-3)-18:0, or tristearin. A fifth group receives standard (n-3) adequate feed AIN-93G from birth till the end of the trial. The DHA-fed groups show significantly higher DHA levels in the liver and visceral fat compared to the tristearin or normal feed groups showing that the dose and the short feeding period of DHA were sufficient to restore the DHA content in the organs of (n-3) deficient rats. Feeding sn-1 DHA resulted in higher levels of DHA in the liver TAG compared to sn-3 DHA feeding, although the difference did not reach statistical significance. These findings indicated a possible difference in the tissue accumulation and/or metabolic fate of DHA from the sn-1 and sn-3 positions of TAG.

Comparative analysis of DHA positional distribution and triacylglycerol molecular species in algal oil (Schizochytrium sp.) from different oil processing

This study aims to analysis the content and positional distribution of docosahexaenoic acid (DHA, 22:6 n-3) in algal oils (Schizochytrium sp.) using both Candida antarctica Lipase B (CAL-B)-catalyzed-transesterification combined with GC and 13C NMR. The triacylglycerol (TAG) molecular species in algal oils were also identified and quantified using LC-MS. The algal oils were from 3 kinds of oil processing including crude oil (CAO), liquid phase and solid phase oils from fractionation (LAO and SAO) as well as re-esterified triacylglycerol (rTAG). Algal oils contain 55%–97% polyunsaturated fatty acids (PUFAs) and 45%–80% DHA of the total oil; and DHA dominantly esterified at sn-2 position of glycerol backbone with the ratio of sn-2 DHA to total DHA ranged from 32% to 48%. A total of 42 TAGs were identified including 27 TAGs contained DHA, of which the 22:6/22:6/22:5 and 22:6/22:6/22:6 were the predominant species. The lipids containing DHA of algal oils are influenced by the fractionation processing. Compared with physical modified algal oils, rTAG has high DHA content (∼80%, P < 0.05) but lower sn-2 DHA relative content (∼32%, P < 0.05). This study provides an effective analysis scheme for high-PUFA-oils which will be used to develop novel functional oils.

Streamlined enzymatic synthesis of human milk fat substitutes

The positional distribution of palmitic acid (PA) in human milk fat substitutes (HMFSs) plays a pivotal role in mimicking the nutritional profile of human milk fat for nourishing non-breastfed infants. This study innovatively introduced a streamlined enzymatic process for preparing HMFSs rich in sn-2 PA using palm stearin, a PA-rich source without the necessity for positional distribution of PA. The initial step involved enhancing the sn-2 PA concentration through enzymatic interesterification using Lipase UM1, which exhibited superior catalytic efficiency than Novozym 435. This process increased the sn-2 PA level from 40.98 % to 64.51 %. Subsequently, acidolysis was employed to reduce PA levels by replacing PA at sn-1,3 positions using sn-1,3-regioselective lipases. The PA content decreased from 60.64 % to 26.73 %, simultaneously raising the relative sn-2 PA concentration to 71.57 %, meeting the benchmarks for HMFSs. This study establishes a robust conceptual framework for the prospective industrial synthesis of HMFSs.

Enabling Predictive Redirection Reset Based on Virtual-Real Spatial Probability Density Distributions.

Redirected walking (RDW) allows users to explore vast virtual spaces by walking in confined real spaces, yet suffers from frequent boundary collisions due to physical constraints. The major solution is to use the reset strategy to steer users away from boundaries. However, most reset methods guide users to fixed spots or follow constant patterns, neglecting spatial features and users' movement trends. In this paper, we propose an innovative predictive reset method based on spatial probability density distribution to jointly involve impacts of spatial feature and walking intention for forecasting the user's possible positional distribution, and thereby determines the optimal reset direction by maximizing walking expectation. Given a space, we calculate the stationary layout energy to indicate traveling difficulties of all positions. Meanwhile, we exploit a novel intention inference model to anticipate the probability distribution of the user's presence across adjacent positions. Furthermore, we incorporate the obstacle energy attenuation to predict the obstacle avoidance behaviors. All aforementioned factors are amalgamated into a potential region energy map, and then we integrate energy maps of virtual and real spaces into a fusion energy map to enable the prediction considering both spaces simultaneously. Thus, the optimal reset direction is derived by maximizing the fusion energy. Simulation and user studies are conducted on a broad dataset containing plentiful virtual and real spaces. The results demonstrate that our method effectively reduces the physical collisions and increase the continuous walking distance compared to prevalent reset methods, while exhibiting superior applicability when combined with various RDW controllers. The source code and dataset are available at https://github.com/huiyuroy/Return2MaxPotentialEnergy.

Evaluating the capability of soybean peptides as calcium ion carriers: a study through sequence analysis and molecular dynamics simulations.

Calcium homeostasis imbalance in the body can lead to a variety of chronic diseases. Supplement efficiency is essential. Peptide calcium chelate, a fourth-generation calcium supplement, offers easy absorption and minimal side effects. Its effectiveness relies on peptide's calcium binding capacity. However, research on amino acid sequences in peptides with high calcium binding capacity (HCBC) is limited, affecting the efficient identification of such peptides. This study used soybean peptides (SP), separated and purified by gel chromatography, to obtain HCBC peptide (137.45 μg mg-1) and normal peptide (≤95.78 μg mg-1). Mass spectrometry identified the sequences of these peptides, and an analysis of the positional distribution of characteristic amino acids followed. Two HCBC peptides with sequences GGDLVS (271.55 μg mg-1) and YEGVIL (272.54 μg mg-1) were discovered. Molecular dynamics showed that when either aspartic acid is located near the N-terminal's middle, or glutamic acid is near the end, or in cases of continuous Asp or Glu, the binding speed, probability, and strength between the peptide and calcium ions are superior compared to those at other locations. The study's goal was to clarify how the positions of characteristic amino acids in peptides affect calcium binding, aiding in developing peptide calcium chelates as a novel calcium supplement.

Exploring Positional Distributions of Labeled Superpixels Within Graph Convolutional Networks for Hyperspectral Image

Exploring Positional Distributions of Labeled Superpixels Within Graph Convolutional Networks for Hyperspectral Image

Specific Patterns in Correlations of Super-Short Tandem Repeats (SSTRs) with G+C Content, Genic and Intergenic Regions, and Retrotransposons on All Human Chromosomes.

The specific characteristics of k-mer words (2 ≤ k ≤ 11) regarding genomic distribution and evolutionary conservation were recently found. Among them are, in high abundance, words with a tandem repeat structure (repeat unit length of 1 bp to 3 bp). Furthermore, there seems to be a class of extremely short tandem repeats (≤12 bp), so far overlooked, that are non-random-distributed and, therefore, may play a crucial role in the functioning of the genome. In the following article, the positional distributions of these motifs we call super-short tandem repeats (SSTRs) were compared to other functional elements, like genes and retrotransposons. We found length- and sequence-dependent correlations between the local SSTR density and G+C content, and also between the density of SSTRs and genes, as well as correlations with retrotransposon density. In addition to many general interesting relations, we found that SINE Alu has a strong influence on the local SSTR density. Moreover, the observed connection of SSTR patterns to pseudogenes and -exons might imply a special role of SSTRs in gene expression. In summary, our findings support the idea of a special role and the functional relevance of SSTRs in the genome.

Detection and analysis of triacylglycerol regioisomers via electron activated dissociation (EAD) tandem mass spectrometry

Triacylglycerols (TGs) are important components of human diet. The positional distribution of fatty acids (FAs) on the glycerol backbone affects the chemistry and physical properties of fats. Especially for infants, the structure of TGs plays an important role in the growth and development. However, limited by detecting technology, accurately identifying regioisomers of ABA/AAB and BAC/ABC/ACB type TGs is a significant challenge for human milk utilization and the development of infant formula. For this, we exploit a novel method for identifying the regioisomers of ABA/AAB and BAC/ABC/ACB type TGs within complex lipid mixtures, via used electron activated dissociation (EAD) tandem mass spectrometry. The distribution information of acyl chains at the sn-2 and sn-1/3 positions of glycerol backbone and double bonds in unsaturated FAs can be easily obtained by fragmenting TG ions with energetic electrons (15 eV). Then, the standard curve was established by correlating the peak area intensity of sn-2 characteristic product ion with the content of TG regioisomers standard. These analytical methods successfully enabled the identification and quantification of TG regioisomers in human milk, cow milk, infant formula, palm oil, and sunflower oil. Additionally, the distribution of the double-bond positions of unsaturated FAs in these samples was also identified. Compared to traditional methods, this approach eliminates the need for complex processing and analysis procedures, enabling rapid structural characterization of ABA/AAB and BAC/ABC/ACB type TGs within 17 min. Hence, we provide a rapid and convenient methodology for detecting and analyzing ABA/AAB and BAC/ABC/ACB type TG regioisomers, thereby offering valuable assistance in the development of specialized formulations and facilitating effective process control for ensuring the quality of edible oils and fats.

In-Depth Structure and Function Characterization of Heterogeneous Interchain Cysteine-Conjugated Antibody-Drug Conjugates.

Antibody-drug conjugates (ADCs), integrating high specificity of antigen-targeting antibodies and high potency of cell-killing chemical drugs, have become one of the most rapidly expanding therapeutic biologics in oncology. Although ADCs were widely studied from multiple aspects, overall structural elucidation with comprehensive understanding of variants is scarcely reported. Here, for the first time, we present a holistic and in-depth characterization of an interchain cysteine-conjugated ADC, focusing on conjugation and charge heterogeneity, and in vitro biological activities. Conjugation mapping utilized a bottom-up approach, unraveled positional isomer composition, provided insights into the conjugation process, and elucidated how conjugation affects the physicochemical and biological properties of an ADC. Charge profiling combined bottom-up and top-down approaches to interrogate the origin of charge heterogeneity, its impact on function, and best practice for characterization. Specifically, we pioneered the utilization of capillary isoelectric focusing-mass spectrometry to decode not only critical post-translational modifications but also drug load and positional isomer distribution. The study design provides general guidance for in-depth characterization of ADCs, and the analytical findings in turn benefit the discovery and development of future ADCs.

The same species, different nutrients: Lipidomics analysis of muscle in mud crabs (Scylla paramamosain) fed with lard oil and fish oil

Aiming to assess the effects of lard oil (LO) and fish oil (FO) on the nutritional value of mud crabs (Scylla paramamosain), non-targeted lipidomics analysis was performed on the muscle of crabs after eight weeks of feeding trail. Compared to FO, dietary LO reduced the content of phosphatidylethanolamine (PE) and phosphatidylserine (PS) with 18:0 bound at sn-1/3 site, the content of ether phospholipids containing 20:5n-3 (EPA) and 22:6n-3 (DHA) combined at sn-2 site, and increased the content of ether PE containing 18:0 and 18:1n-9. Furthermore, the deposition of 16:0, 16:1n-7, 18:2n-6, 18:3n-3, 20:4n-6, EPA and DHA at each site of PE, PS, phosphatidylcholine and/or triacylglycerols were reduced by dietary LO, while the DHA content at the sn-2 position of PE was increased. In conclusion, the nutritional value of mud crabs was reduced by dietary LO with the manifestation of variation in FA composition and positional distribution on phospholipids.

Acylation of glycerolipids in mycobacteria

We report on the existence of two phosphatidic acid biosynthetic pathways in mycobacteria, a classical one wherein the acylation of the sn-1 position of glycerol-3-phosphate (G3P) precedes that of sn-2 and another wherein acylations proceed in the reverse order. Two unique acyltransferases, PlsM and PlsB2, participate in both pathways and hold the key to the unusual positional distribution of acyl chains typifying mycobacterial glycerolipids wherein unsaturated substituents principally esterify position sn-1 and palmitoyl principally occupies position sn-2. While PlsM selectively transfers a palmitoyl chain to the sn-2 position of G3P and sn-1-lysophosphatidic acid (LPA), PlsB2 preferentially transfers a stearoyl or oleoyl chain to the sn-1 position of G3P and an oleyl chain to sn-2-LPA. PlsM is the first example of an sn-2 G3P acyltransferase outside the plant kingdom and PlsB2 the first example of a 2-acyl-G3P acyltransferase. Both enzymes are unique in their ability to catalyze acyl transfer to both G3P and LPA.

Where the minor things are: a pan-eukaryotic survey suggests neutral processes may explain much of minor intron evolution.

Spliceosomal introns are gene segments removed from RNA transcripts by ribonucleoprotein machineries called spliceosomes. In some eukaryotes a second 'minor' spliceosome is responsible for processing a tiny minority of introns. Despite its seemingly modest role, minor splicing has persisted for roughly 1.5 billion years of eukaryotic evolution. Identifying minor introns in over 3000 eukaryotic genomes, we report diverse evolutionary histories including surprisingly high numbers in some fungi and green algae, repeated loss, as well as general biases in their positional and genic distributions. We estimate that ancestral minor intron densities were comparable to those of vertebrates, suggesting a trend of long-term stasis. Finally, three findings suggest a major role for neutral processes in minor intron evolution. First, highly similar patterns of minor and major intron evolution contrast with both functionalist and deleterious model predictions. Second, observed functional biases among minor intron-containing genes are largely explained by these genes' greater ages. Third, no association of intron splicing with cell proliferation in a minor intron-rich fungus suggests that regulatory roles are lineage-specific and thus cannot offer a general explanation for minor splicing's persistence. These data constitute the most comprehensive view of minor introns and their evolutionary history to date, and provide a foundation for future studies of these remarkable genetic elements.

Fatty acid concentration and distribution in human milk: Comparison with infant formulas and animal milk

AbstractThe lipid profile including total fatty acid (FA), sn‐2 positional distribution on triacylglycerol, and phospholipid (PL) FA in human milk, infant formulas, and animal milk (cow, goat, camel, donkey, and yak milk) were analyzed. Animal milk contained higher saturated fatty acids (45.08%–66.29%) than human milk (37.44%) and infant formula (33.46%). In the perspective of FA, human milk and the commercial formulas showed a better similarity. Human milk contained significantly (p &lt; 0.05) higher 16:0 at the sn‐2 position (50.88%) than infant formulas (23.09%) and animal milk (28.95%–46.72%). As to PL‐FA, human milk contained significantly (p &lt; 0.05) higher 16:0 and 18:0 but lower 18:1 n‐9 than other milk. The relative contents of arachidonic acid (AA), docosahexaenoic acid (DHA), and nervonic acid (NA) in human milk were higher in PL‐FA than that in total FA. Noteworthy, the contents of AA, DHA, and NA in both total FA and PL‐FA were higher in human milk than other milk. These results indicated that the fortification of 16:0 at the sn‐2 position, and AA, DHA, and NA in both total FA and PL‐FA could improve the quality of infant formulas.

Numerical investigations on the absorption of a metal hydride hydrogen storage tank based on various thermal management strategies

This study presents numerical investigations on the performance of the charging process of a metal hydride-based hydrogen storage tank. Three scenarios were developed to examine the absorption performance and compare the effectivenesses of proposed thermal management alternatives. In Scenario-1, the metal hydride (MH) tank is cooled with convective heat transfer on the lateral surface of the tank, i.e., external convection. In Scenario-2, phase change material (PCM) is wrapped around the MH tank to investigate passive thermal management. Scenario-3, a hybrid approach, includes the PCM layer and an internal cooling pipe. In this scenario, the heat transfer fluid (HTF) inside the tube is activated depending on the temperature within the MH tank. An in-house 2D axisymmetric numerical code was developed using the finite volume approach in MATLAB software. In the parametric study, several design parameters and operating conditions were selected, such as (i) charging pressure, (ii) external convective heat transfer coefficient, (iii) PCM thickness, (iv) latent heat of PCM, (v) HTF temperature, and (vi) convective heat transfer coefficient of the HTF, and as a total of 334 parametric analyses were conducted by varying the numerical values of the parameters chosen in wide ranges. The outputs, like spatial and temporal variations of hydride bed temperature and weight fraction, are evaluated for each of the proposed scenarios. As a result, it was observed that the storage performance strongly depends on the convection coefficient at ambient conditions. In Scenario-1, beyond 1000 W/m2K, convective heat transfer coefficient variations do not cause a significant change in the charging process. In Scenario-2, variations in PCM thickness do not cause a considerable change in the storage performance significantly beyond 3 cm. The variations in PCM thickness become important at lower latent heat values and PCM thicknesses less than 2.5 cm. In Scenario-2 and Scenario-3, PCM thickness over 2.5 cm and latent heat of fusion parameter over 150 kJ/kg should be selected to provide a thermal management strategy to be implemented. While the storage criteria were determined according to different thermal management strategies, the PCM thickness and latent heat of fusion parameters showed higher storage performance than the external convection coefficient at the same charging pressure. Temperatures at critical nodes in the MH-PCM system vary depending on location and reaction time. For all thermal management strategies in the hydride bed in positional temperature distributions, the temperature is minimum at the nodes close to the straight pipe. In the scenario-based analysis of the hydride bed temperature, the Scenario-3 thermal management strategy provides the MH bed domain at a lower temperature than Scenario-2. Here, the convection coefficient inside the cooling channel is a critical parameter for the hydride bed temperature.

0526 Effect of Body Position and Sleep State on Sleep Disordered Breathing Distribution in Infants Ages 6 to 12 months

Abstract Introduction The effect of body position and sleep state on events distribution in infants ages 6 to 12 months needs further study. We aimed to study this distribution and determine the difference of body position in infants with and without sleep disordered breathing. Methods This was a single center, retrospective study that included infants ages 6 to 12 months who were evaluated for suspected sleep disordered breathing and underwent a full overnight polysomnography in an academic sleep disorders center over a period of 10 years. Infants with ages 6 to 12 months with obstructive sleep apnea hypopnea index (OAHI) and central apnea index (CAI) ≥ 1 (sleep disordered breathing [SDB] group) were compared with infants with normal AHI who represented the control group (CG). Total OAHI, CAI, apnea hypopnea index (AHI) in different body positions, rapid eye movement (REM), and Non-REM sleep were collected. Results A total of 36 infants had SDB and 18 infants had normal AHI. The median age was not significantly different between both groups with a median age of 10 months (IQR 7.75-11) in SDB group and 8.5 months in CG (IQR 7.25- 10.00) (p=0.258). Male sex was predominant in both groups (58.3% in SDB group and 61.1% in CG). There were no significant differences between both groups in the BMI, median total sleep time, REM% sleep time, and Non-REM% sleep time. The supine sleep time in the SDB group [258.90 minutes (IQR 149.35-381.25)] was significantly higher than the supine sleep time in the CG [165.90 minutes (IQR 54.55 to 285.05)] (p=0.035). In the SDB group, REM AHI [8.55 (IQR 5.02 – 15.25] was significantly higher than Non-REM AHI [0.50 (IQR 0.30-1.20)] (p&amp;lt; 0.001). In the SDB group, there were no significant differences in the supine vs. off-supine distribution of respiratory events. Conclusion Obstructive and central respiratory events in infants ages 6 to 12 months occurred predominantly in REM sleep compared to Non-REM sleep. Infants with SDB significantly spent more time in supine position when compared to infants without SDB but the respiratory events distribution in infants with SDB did not have a significant positional distribution. Support (if any)

Enzymatic synthesis and purification of diacylglycerols from mutton tallow and hemp seed oil

Abstract: Production of preparations based on natural ingredients has become a priority in the cosmetic and pharmaceutical industries. The novelty of the study was to present a possible method for obtaining pure diacylglycerols (DAG) from natural raw materials like fats (hemp seed oil and mutton tallow). We have determined the optimum water content for enzymatic interesterification to shift the reaction equilibrium towards hydrolysis and obtain the highest DAG formation yield. Then, DAG were separated and purified by column chromatography. Raw fats were characterized by fatty acids composition and their positional distribution using gas chromatography. Triacylglycerols, diacylglycerols, monoacylglycerols and free fatty acid contents were determined using gel permeation chromatography. The main fatty acids found in sn-2 MAG of hemp seed oil was linoleic acid, which was followed by oleic acid. Saturated fatty acids in hemp seed oil’s TAG showed preference for the outer sn-1,3 positions. For mutton tallow, the majority of oleic acid were found at sn-2 position. The optimum water content applied during enzymatic interesterification for DAG formation was estimated to be 2.0 % w/w, using the following conditions: 5 % w/w of catalyst, 200 rpm, 60 °C, 6h. DAG yield was 27 %. Purification of the mutton tallow-based and hemp seed oil-based DAG yielded with 83 % w/w and 82 % w/w, respectively. High purity DAG could be applied as effective emulsifiers in food, cosmetic or pharmaceutical emulsions.

Effects of Chemically Interesterified Palm Olein on Lipid Profiles in Hamsters

Palm olein (POo) has been perceived as atherogenic due to its high proportion of palmitic acid (41.2%) content. It is interesting that most of the palmitic acid of POo is located at stereospecific numbering sn-1 and sn-3 positions of the triacylglycerol (TAG) backbone. The present study aims to investigate the effects of positional distribution of fatty acids on the lipid profiles of POo or chemically interesterified palm olein (CIE POo) fed hamsters in comparison to high oleic sunflower oil (HOSO) fed hamsters. Male weanling Syrian golden hamsters (n=10 for each group), were fed diets formulated with the above oils for 12 weeks. There was no significant difference between CIE POo and HOSO groups for total cholesterol (TC). CIE POo with increased amount of palmitic acid (43.2%) at sn-2 position did not cause significant increases in TC levels compared to the HOSO group. In addition, the POo group has significantly higher high-density lipoprotein cholesterol (HDL-C) than that of the HOSO group, P = 0.011 (&lt; 0.05) while the HOSO group has significantly lower total cholesterol (TC) levels than that of the POo group, P = 0.012 (&lt; 0.05).

The Positional Distribution of Fatty Acids in Palm Oil and Lard Influences Their Biologic Effects in Rats

Dietary fatty acids in the sn-2 position are preferentially absorbed as monoacylglycerols. To determine whether they also have more important biologic effects, rats were fed for 2 and 4 mo a purified diet containing native palm oil, interesterified palm oil, native lard or interesterified lard. Interesterification that increased or decreased the level of fatty acids in position 2 depending on the fat, resulted in significant corresponding changes in the fecal excretion of saturated fatty acids. Fecal excretion of saturated fatty acids was associated with significant changes in some plasma fatty acids. Interesterification in lard resulted in significantly lower plasma triglycerides, and in palm oil, increased platelet aggregation induced by ADP. Lipemia, platelet aggregation and associated plasma fatty acids (palmitic, heneicosanoic and docosahexaenoic acids) were significantly affected only by dietary fatty acids at the sn-2 position. Even without changes in absorption, only linoleic acid in position 2 was correlated with the plasma concentration of the corresponding longer chain arachidonic acid. These results in rats confirm that the fatty acids (saturated and unsaturated) in position 2 of dietary triglycerides play a crucial role in the metabolism and biologic effects of these fatty acids.

The effects of photoperiod and temperature-related factors on maize leaf number and leaf positional distribution in the field.

Quantifying the effects of various environmental conditions on maize leaf number is essential to understanding the environmental adaptations and population structure of maize plants and for enhancing maize productivity. In this study, seeds of three temperate-adapted maize cultivars, each belonging to different maturity classes, were sown on eight different dates. Sowing dates ranged from the middle of April to early July, which allowed us to cover a wide range of environmental conditions. Random forest regression and multiple regression models with variance partitioning analyses were used to assess the effects of environmental factors on the number of leaves and their distributions on maize primary stems. We demonstrated that the total leaf number (TLN) increased in the three cultivars in the following order: FK139 < JNK728 < ZD958, and variations in TLN for each cultivar were 1.5, 1.76, and 2.75 leaves, respectively. The variation in TLN was ascribed to changes in LB (leaf number below the primary ear), which were higher than variations in LA (leaf number above the primary ear). Variations in TLN and LB were mainly affected by the photoperiod during growth stages V7 to V11, and differences in TLN and LB in response to different photoperiods ranged from 1.34 to 2.95 leaves h-l. Variations in LA was mainly affected by temperature-related factors. Therefore, the results of this study enhanced our current understanding of key environmental conditions that affect maize leaf numbers, and provides scientific support for the benefits of adjusting sowing dates and selecting suitable cultivars to mitigate the effects of climate change on maize production.

Positional correction of a 3D position-sensitive virtual Frisch-grid CZT detector for gamma spectroscopy and imaging based on a theoretical assumption

The virtual Frisch-grid method for room-temperature radiation detectors has been widely used because of its simplicity and high performance. Recently, side electrodes were separately attached to each surface of the detectors instead of covering the entire detector surface with a single electrode. The side-electrode structure enables the measurement of the three-dimensional (3D) gamma-ray interaction in the detector. The positional information of the interaction can then be utilized to precisely calibrate the response of the detector for gamma-ray spectroscopy and imaging. In this study, we developed a 3D position-sensitive 5 × 5 × 12 mm3 cadmium-zinc-telluride (CZT) detector and applied a flattening method to correct detector responses. Collimated gamma-rays incident on the surface of the detector were scanned to evaluate the positional accuracy of the detection system. Positional distributions of the radiation interactions with the detector were imaged for quantitative and qualitative evaluation. The energy spectra of various radioisotopes were measured and improved by the detector response calibration according to the calculated positional information. The energy spectra ranged from 59.5 keV (emitted by 241Am) to 1332 keV (emitted by 60Co). The best energy resolution was 1.06% at 662 keV when the CZT detector was voxelized to 20 × 20 × 10.